From 8efc0c151a0f57612e1aa0abb5b7d536db4cf76a Mon Sep 17 00:00:00 2001 From: damien Date: Wed, 27 Oct 1999 03:42:43 +0000 Subject: [PATCH] Initial revision --- COPYING.Ylonen | 70 ++ ChangeLog | 578 +++++++++++ ChangeLog.linux | 20 + Makefile | 13 + Makefile.GNU | 50 + Makefile.inc | 11 + OVERVIEW | 164 ++++ README | 563 +++++++++++ README.openssh | 44 + RFC.nroff | 1780 ++++++++++++++++++++++++++++++++++ auth-krb4.c | 209 ++++ auth-passwd.c | 209 ++++ auth-rh-rsa.c | 83 ++ auth-rhosts.c | 298 ++++++ auth-rsa.c | 478 +++++++++ auth-skey.c | 149 +++ authfd.c | 565 +++++++++++ authfd.h | 102 ++ authfile.c | 350 +++++++ bufaux.c | 141 +++ bufaux.h | 51 + buffer.c | 150 +++ buffer.h | 66 ++ canohost.c | 234 +++++ channels.c | 1500 +++++++++++++++++++++++++++++ channels.h | 41 + cipher.c | 304 ++++++ cipher.h | 84 ++ clientloop.c | 924 ++++++++++++++++++ compat.c | 10 + compat.h | 7 + compress.c | 160 ++++ compress.h | 46 + crc32.c | 120 +++ crc32.h | 25 + deattack.c | 180 ++++ deattack.h | 27 + getput.h | 64 ++ helper.c | 108 +++ helper.h | 43 + hostfile.c | 279 ++++++ includes.h | 78 ++ log-client.c | 138 +++ log-server.c | 233 +++++ login.c | 118 +++ match.c | 78 ++ mktemp.c | 181 ++++ mktemp.h | 7 + mpaux.c | 46 + mpaux.h | 32 + nchan.c | 187 ++++ nchan.h | 57 ++ nchan.ms | 71 ++ openssh.spec | 105 ++ packet.c | 762 +++++++++++++++ packet.h | 166 ++++ pty.c | 264 +++++ pty.h | 40 + radix.c | 258 +++++ rc4.c | 105 ++ rc4.h | 110 +++ readconf.c | 684 +++++++++++++ readconf.h | 116 +++ readpass.c | 114 +++ rsa.c | 164 ++++ rsa.h | 36 + scp.1 | 110 +++ scp.c | 1220 +++++++++++++++++++++++ servconf.c | 567 +++++++++++ servconf.h | 86 ++ serverloop.c | 644 +++++++++++++ ssh-add.1 | 116 +++ ssh-add.c | 254 +++++ ssh-agent.1 | 124 +++ ssh-agent.c | 572 +++++++++++ ssh-keygen.1 | 155 +++ ssh-keygen.c | 552 +++++++++++ ssh.1 | 966 +++++++++++++++++++ ssh.c | 809 ++++++++++++++++ ssh.h | 589 ++++++++++++ ssh.pam | 7 + ssh_config | 30 + sshconnect.c | 1495 +++++++++++++++++++++++++++++ sshd.8 | 781 +++++++++++++++ sshd.c | 2445 +++++++++++++++++++++++++++++++++++++++++++++++ sshd.init | 49 + sshd_config | 44 + strlcpy.c | 68 ++ strlcpy.h | 4 + tildexpand.c | 70 ++ ttymodes.c | 359 +++++++ ttymodes.h | 138 +++ uidswap.c | 95 ++ uidswap.h | 30 + version.h | 1 + xmalloc.c | 56 ++ xmalloc.h | 34 + 97 files changed, 26920 insertions(+) create mode 100644 COPYING.Ylonen create mode 100644 ChangeLog create mode 100644 ChangeLog.linux create mode 100644 Makefile create mode 100644 Makefile.GNU create mode 100644 Makefile.inc create mode 100644 OVERVIEW create mode 100644 README create mode 100644 README.openssh create mode 100644 RFC.nroff create mode 100644 auth-krb4.c create mode 100644 auth-passwd.c create mode 100644 auth-rh-rsa.c create mode 100644 auth-rhosts.c create mode 100644 auth-rsa.c create mode 100644 auth-skey.c create mode 100644 authfd.c create mode 100644 authfd.h create mode 100644 authfile.c create mode 100644 bufaux.c create mode 100644 bufaux.h create mode 100644 buffer.c create mode 100644 buffer.h create mode 100644 canohost.c create mode 100644 channels.c create mode 100644 channels.h create mode 100644 cipher.c create mode 100644 cipher.h create mode 100644 clientloop.c create mode 100644 compat.c create mode 100644 compat.h create mode 100644 compress.c create mode 100644 compress.h create mode 100644 crc32.c create mode 100644 crc32.h create mode 100644 deattack.c create mode 100644 deattack.h create mode 100644 getput.h create mode 100644 helper.c create mode 100644 helper.h create mode 100644 hostfile.c create mode 100644 includes.h create mode 100644 log-client.c create mode 100644 log-server.c create mode 100644 login.c create mode 100644 match.c create mode 100644 mktemp.c create mode 100644 mktemp.h create mode 100644 mpaux.c create mode 100644 mpaux.h create mode 100644 nchan.c create mode 100644 nchan.h create mode 100644 nchan.ms create mode 100644 openssh.spec create mode 100644 packet.c create mode 100644 packet.h create mode 100644 pty.c create mode 100644 pty.h create mode 100644 radix.c create mode 100644 rc4.c create mode 100644 rc4.h create mode 100644 readconf.c create mode 100644 readconf.h create mode 100644 readpass.c create mode 100644 rsa.c create mode 100644 rsa.h create mode 100644 scp.1 create mode 100644 scp.c create mode 100644 servconf.c create mode 100644 servconf.h create mode 100644 serverloop.c create mode 100644 ssh-add.1 create mode 100644 ssh-add.c create mode 100644 ssh-agent.1 create mode 100644 ssh-agent.c create mode 100644 ssh-keygen.1 create mode 100644 ssh-keygen.c create mode 100644 ssh.1 create mode 100644 ssh.c create mode 100644 ssh.h create mode 100644 ssh.pam create mode 100644 ssh_config create mode 100644 sshconnect.c create mode 100644 sshd.8 create mode 100644 sshd.c create mode 100755 sshd.init create mode 100644 sshd_config create mode 100644 strlcpy.c create mode 100644 strlcpy.h create mode 100644 tildexpand.c create mode 100644 ttymodes.c create mode 100644 ttymodes.h create mode 100644 uidswap.c create mode 100644 uidswap.h create mode 100644 version.h create mode 100644 xmalloc.c create mode 100644 xmalloc.h diff --git a/COPYING.Ylonen b/COPYING.Ylonen new file mode 100644 index 00000000..5e681edd --- /dev/null +++ b/COPYING.Ylonen @@ -0,0 +1,70 @@ +This file is part of the ssh software, Copyright (c) 1995 Tatu Ylonen, Finland + + +COPYING POLICY AND OTHER LEGAL ISSUES + +As far as I am concerned, the code I have written for this software +can be used freely for any purpose. Any derived versions of this +software must be clearly marked as such, and if the derived work is +incompatible with the protocol description in the RFC file, it must be +called by a name other than "ssh" or "Secure Shell". + +However, I am not implying to give any licenses to any patents or +copyrights held by third parties, and the software includes parts that +are not under my direct control. As far as I know, all included +source code is used in accordance with the relevant license agreements +and can be used freely for any purpose (the GNU license being the most +restrictive); see below for details. + +[ RSA is no longer included. ] +[ IDEA is no longer included. ] +[ DES is now external. ] +[ GMP is now external. No more GNU licence. ] +[ Zlib is now external. ] +[ The make-ssh-known-hosts script is no longer included. ] +[ TSS has been removed. ] +[ MD5 is now external. ] +[ RC4 support has been removed. ] +[ Blowfish is now external. ] + +The 32-bit CRC implementation in crc32.c is due to Gary S. Brown. +Comments in the file indicate it may be used for any purpose without +restrictions. + +The 32-bit CRC compensation attack detector in deattack.c was +contributed by CORE SDI S.A. under a BSD-style license. See +http://www.core-sdi.com/english/ssh/ for details. + +Note that any information and cryptographic algorithms used in this +software are publicly available on the Internet and at any major +bookstore, scientific library, and patent office worldwide. More +information can be found e.g. at "http://www.cs.hut.fi/crypto". + +The legal status of this program is some combination of all these +permissions and restrictions. Use only at your own responsibility. +You will be responsible for any legal consequences yourself; I am not +making any claims whether possessing or using this is legal or not in +your country, and I am not taking any responsibility on your behalf. + + + NO WARRANTY + +BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY +FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN +OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES +PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED +OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF +MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS +TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE +PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, +REPAIR OR CORRECTION. + +IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING +WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR +REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, +INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING +OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED +TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY +YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER +PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE +POSSIBILITY OF SUCH DAMAGES. diff --git a/ChangeLog b/ChangeLog new file mode 100644 index 00000000..08d90f78 --- /dev/null +++ b/ChangeLog @@ -0,0 +1,578 @@ +Fri Nov 17 16:19:20 1995 Tatu Ylonen + + * Released 1.2.12. + + * channels.c: Commented out debugging messages about output draining. + + * Added file OVERVIEW to give some idea about the structure of the + ssh software. + +Thu Nov 16 16:40:17 1995 Tatu Ylonen + + * canohost.c (get_remote_hostname): Don't ever return NULL (causes + segmentation violation). + + * sshconnect.c: Host ip address printed incorrectly with -v. + + * Implemented SSH_TTY environment variable. + +Wed Nov 15 01:47:40 1995 Tatu Ylonen + + * Implemented server and client option KeepAlive to specify + whether to set SO_KEEPALIVE. Both default to "yes"; to disable + keepalives, set the value to "no" in both the server and the + client configuration files. Updated manual pages. + + * sshd.c: Fixed Solaris utmp problem: wrong pid stored in utmp + (patch from Petri Virkkula ). + + * login.c (record_logout): Fixed removing user from utmp on BSD + (with HAVE_LIBUTIL_LOGIN). + + * Added cleanup functions to be called from fatal(). Arranged for + utmp to be cleaned if sshd terminates by calling fatal (e.g., + after dropping connection). Eliminated separate client-side + fatal() functions and moved fatal() to log-client.c. Made all + cleanups, including channel_stop_listening() and packet_close() + be called using this mechanism. + +Thu Nov 9 09:58:05 1995 Tatu Ylonen + + * sshd.c: Permit immediate login with empty password only if + password authentication is allowed. + +Wed Nov 8 00:43:55 1995 Tatu Ylonen + + * Eliminated unix-domain X11 forwarding. Inet-domain forwarding is + now the only supported form. Renamed server option + X11InetForwarding to X11Forwarding, and eliminated + X11UnixForwarding. Updated documentation. Updated RFC (marked + the SSH_CMSG_X11_REQUEST_FORWARDING message (code 26) as + obsolete, and removed all references to it). Increased protocol + version number to 1.3. + + * scp.c (main): Added -B (BatchMode). Updated manual page. + + * Cleaned up and updated all manual pages. + + * clientloop.c: Added new escape sequences ~# (lists forwarded + connections), ~& (background ssh when waiting for forwarded + connections to terminate), ~? (list available escapes). + Polished the output of the connection listing. Updated + documentation. + + * uidswap.c: If _POSIX_SAVED_IDS is defined, don't change the real + uid. Assume that _POSIX_SAVED_IDS also applies to seteuid. + This may solve problems with tcp_wrappers (libwrap) showing + connections as coming from root. + +Tue Nov 7 20:28:57 1995 Tatu Ylonen + + * Added RandomSeed server configuration option. The argument + specifies the location of the random seed file. Updated + documentation. + + * Locate perl5 in configure. Generate make-ssh-known-hosts (with + the correct path for perl5) in Makefile.in, and install it with + the other programs. Updated manual page. + + * sshd.c (main): Added a call to umask to set the umask to a + reasonable value. + + * compress.c (buffer_compress): Fixed to follow the zlib + documentation (which is slightly confusing). + + * INSTALL: Added information about Linux libc.so.4 problem. + +Mon Nov 6 15:42:36 1995 Tatu Ylonen + + * (Actually autoconf fix) Installed patch to AC_ARG_PROGRAM. + + * sshd.c, sshd.8.in: Renamed $HOME/.environment -> + $HOME/.ssh/environment. + + * configure.in: Disable shadow password checking on convex. + Convex has /etc/shadow, but sets pw_passwd automatically if + running as root. + + * Eliminated HAVE_ETC_MASTER_PASSWD (NetBSD, FreeBSD); the + pw_passwd field is automatically filled if running as root. + Put explicit code in configure.in to prevent shadow password + checking on FreeBSD and NetBSD. + + * serverloop.c (signchld_handler): Don't print error if wait + returns -1. + + * Makefile.in (install): Fixed modes of data files. + + * Makefile.in (install): Make links for slogin.1. + + * make-ssh-known-hosts: Merged a patch from melo@ci.uminho.pt to + fix the ping command. + +Fri Nov 3 16:25:28 1995 Tatu Ylonen + + * ssh.1.in: Added more information about X11 forwarding. + +Thu Nov 2 18:42:13 1995 Tatu Ylonen + + * Changes to use O_NONBLOCK_BROKEN consistently. + + * pty.c (pty_make_controlling_tty): Use setpgid instead of + setsid() on Ultrix. + + * includes.h: Removed redundant #undefs for Ultrix and Sony News; + these are already handled in configure.in. + +Tue Oct 31 13:31:28 1995 Tatu Ylonen + + * configure.in: Define SSH_WTMP to /var/adm/wtmp is wtmp not found. + + * configure.in: Disable vhangup on Ultrix. I am told this fixes + the server problems. + +Sat Oct 28 14:22:05 1995 Tatu Ylonen + + * sshconnect.c: Fixed a bug in connecting to a multi-homed host. + Restructured the connecting code to never try to use the same + socket a second time after a failed connection. + + * Makefile.in: Added explicit -m option to install, and umask 022 + when creating directories and the host key. + +Fri Oct 27 01:05:10 1995 Tatu Ylonen + + * Makefile.in: Added cleaning of $(ZLIBDIR) to clean and distclean. + + * login.c (get_last_login_time): Fixed a typo (define -> defined). + +Thu Oct 26 01:28:07 1995 Tatu Ylonen + + * configure.in: Moved testing for ANSI C compiler after the host + specific code (problems on HPUX). + + * Minor fixes to /etc/default/login stuff from Bryan O'Sullivan. + + * Fixed .SH NAME sections in manual pages. + + * compress.c: Trying to fix a mysterious bug in the compression + glue. + + * ssh-1.2.11. + + * scp.c: disable agent forwarding when running ssh from scp. + + * Added compression of plaintext packets using the gzip library + (zlib). Client configuration options Compression and + CompressionLevel (1-9 as in gzip). New ssh and scp option -C + (to enable compression). Updated RFC. + +Wed Oct 25 05:11:55 1995 Tatu Ylonen + + * Implemented ProxyCommand stuff based on patches from Bryan + O'Sullivan . + + * Merged BSD login/logout/lastlog patches from Mark Treacy + . + + * sshd.c: Added chdir("/"). + +Tue Oct 24 00:29:01 1995 Tatu Ylonen + + * Merged RSA environment= patches from Felix Leitner + with some changes. + + * sshd.c: Made the packet code use two separate descriptors for + the connection (one for input, the other for output). This will + make future extensions easier (e.g., non-socket transports, etc.). + sshd -i now uses both stdin and stdout separately. + +Mon Oct 23 21:29:28 1995 Tatu Ylonen + + * sshd.c: Merged execle -> execve patches from Mark Martinec + . This may help with execle bugs on + Convex (environment not getting passed properly). This might + also solve similar problems on Sonys; please test! + + * Removed all compatibility code for protocol version 1.0. + THIS MEANS THAT WE ARE NO LONGER COMPATIBLE WITH SSH VERSIONS + PRIOR TO 1.1.0. + + * randoms.c (random_acquire_light_environmental_noise): If + /dev/random is available, read up to 32 bytes (256 bits) from + there in non-blocking mode, and mix the new random bytes into + the pool. + + * Added client configuration option StrictHostKeyChecking + (disabled by default). If this is enabled, the client will not + automatically add new host keys to $HOME/.ssh/known_hosts; + instead the connection will be refused if the host key is not + known. Similarly, if the host key has changed, the connection + will be refused instead if just issuing a warning. This + provides additional security against man-in-the-middle/trojan + horse attacks (especially in scripts where there is no-one to + see the warnings), but may be quite inconvenient in everyday + interactive use unless /etc/ssh_known_hosts is very complete, + because new host keys must now be added manually. + + * sshconnect.c (ssh_connect): Use the user's uid when creating the + socket and connecting it. I am hoping that this might help with + tcp_wrappers showing the remote user as root. + + * ssh.c: Try inet-domain X11 forwarding regardless of whether we + can get local authorization information. If we don't, we just + come up with fake information; the forwarding code will anyway + generate its own fake information and validate that the client + knows that information. It will then substitute our fake + information for that, but that info should get ignored by the + server if it doesn't support it. + + * Added option BatchMode to disable password/passphrase querying + in scripts. + + * auth-rh-rsa.c: Changed to use uid-swapping when reading + .ssh/known_hosts. + + * sshd.8.in (command): Improved documentation of file permissions + on the manual pages. + +Thu Oct 19 21:05:51 1995 Tatu Ylonen + + * ssh-add.c (add_file): Fixed a bug causing ssh to sometimes refer + to freed memory (comment -> saved_comment). + + * log-server.c: Added a prefix to debug/warning/error/fatal + messages describing message types. Syslog does not include that + information automatically. + +Sun Oct 8 01:56:01 1995 Tatu Ylonen + + * Merged /etc/default/login and MAIL environment variable changes + from Bryan O'Sullivan . + - mail spool file location + - process /etc/default/login + - add HAVE_ETC_DEFAULT_LOGIN + - new function child_get_env and read_etc_default_login (sshd.c) + + * ssh-add.c (add_file): Fixed asking for passphrase. + + * Makefile.in: Fixed installing configure-generated man pages when + compiling in a separate object directory. + + * sshd.c (main): Moved RSA key generation until after allocating + the port number. (Actually, the code got duplicated because we + never listen when run from inetd.) + + * ssh.c: Fixed a problem that caused scp to hang when called with + stdin closed. + +Sat Oct 7 03:08:06 1995 Tatu Ylonen + + * Added server config option StrictModes. It specifies whether to + check ownership and modes of home directory and .rhosts files. + + * ssh.c: If ssh is renamed/linked to a host name, connect to that + host. + + * serverloop.c, clientloop.c: Ignore EAGAIN reported on read from + connection. Solaris has a kernel bug which causes select() to + sometimes wake up even though there is no data available. + + * Display all open connections when printing the "Waiting for + forwarded connections to terminate" message. + + * sshd.c, readconf.c: Added X11InetForwarding and + X11UnixForwarding server config options. + +Thu Oct 5 17:41:16 1995 Tatu Ylonen + + * Some more SCO fixes. + +Tue Oct 3 01:04:34 1995 Tatu Ylonen + + * Fixes and cleanups in README, INSTALL, COPYING. + +Mon Oct 2 03:36:08 1995 Tatu Ylonen + + * ssh-add.c (add_file): Fixed a bug in ssh-add (xfree: NULL ...). + + * Removed .BR from ".SH NAME" in man pages. + +Sun Oct 1 04:16:07 1995 Tatu Ylonen + + * ssh-1.2.10. + + * configure.in: When checking that the compiler works, check that + it understands ANSI C prototypes. + + * Made uidswap error message a debug() to avoid confusing errors + on AIX (AIX geteuid is brain-damaged and fails even for root). + + * Fixed an error in sshd.8 (FacistLogging -> FascistLogging). + + * Fixed distribution in Makefile.in (missing manual page .in files). + +Sat Sep 30 17:38:46 1995 Tatu Ylonen + + * auth-rhosts.c: Fixed serious security problem in + /etc/hosts.equiv authentication. + +Fri Sep 29 00:41:02 1995 Tatu Ylonen + + * Include machine/endian.h on Paragon. + + * ssh-add.c (add_file): Made ssh-add keep asking for the + passphrase until the user just types return or cancels. + Make the dialog display the comment of the key. + + * Read use shosts.equiv in addition to /etc/hosts.equiv. + + * sshd.8 is now sshd.8.in and is processed by configure to + substitute the proper paths for various files. Ditto for ssh.1. + Ditto for make-ssh-known-hosts.1. + + * configure.in: Moved /etc/sshd_pid to PIDDIR/sshd.pid. PIDDIR + will be /var/run if it exists, and ETCDIR otherwise. + +Thu Sep 28 21:52:42 1995 Tatu Ylonen + + * On Ultrix, check if sys/syslog.h needs to be included in + addition to syslog.h. + + * make-ssh-known-hosts.pl: Merged Kivinen's fixes for HPUX. + + * configure.in: Put -lwrap, -lsocks, etc. at the head of LIBS. + + * Fixed case-insensitivity in auth-rhosts.c. + + * Added missing socketpair.c to EXTRA_SRCS (needed on SCO), plus + other SCO fixes. + + * Makefile.in: Fixed missing install_prefixes. + +Wed Sep 27 03:57:00 1995 Tatu Ylonen + + * ssh-1.2.9. + + * Added SOCKS support. + + * Fixed default setting of IgnoreRhosts option. + + * Pass the magic cookie to xauth in stdin instead of command line; + the command line is visible in ps. + + * Added processing $HOME/.ssh/rc and /etc/sshrc. + + * Added a section to sshd.8 on what happens at login time. + +Tue Sep 26 01:27:40 1995 Tatu Ylonen + + * Don't define speed_t on SunOS 4.1.1; it conflicts with system + headers. + + * Added support for .hushlogin. + + * Added --with-etcdir. + + * Read $HOME/.environment after /etc/environment. + +Mon Sep 25 03:26:06 1995 Tatu Ylonen + + * Merged patches for SCO Unix (from Michael Henits). + +Sun Sep 24 22:28:02 1995 Tatu Ylonen + + * Added ssh option ConnectionAttempts. + +Sat Sep 23 12:30:15 1995 Tatu Ylonen + + * sshd.c: Don't print last login time and /etc/motd if a command + has been specified (with ssh -t host command). + + * Added support for passing the screen number in X11 forwarding. + It is implemented as a compatible protocol extension, signalled + by SSH_PROTOFLAG_SCREEN_NUMBER by the child. + + * clientloop.c: Fixed bugs in the order in which things were + processed. This may solve problems with some data not getting + sent to the server as soon as possible (probably solves the TCP + forwarding delayed close problem). Also, it looked like window + changes might not get transmitted as early as possible in some + cases. + + * clientloop.c: Changed to detect window size change that + happened while ssh was suspended. + + * ssh.c: Moved the do_session function (client main loop) to + clientloop.c. Divided it into smaller functions. General cleanup. + + * ssh-1.2.8 + +Fri Sep 22 22:07:46 1995 Tatu Ylonen + + * sshconnect.c (ssh_login): Made ssh_login take the options + structure as argument, instead of the individual arguments. + + * auth-rhosts.c (check_rhosts_file): Added support for netgroups. + + * auth-rhosts.c (check_rhosts_file): Added support for negated + entries. + +Thu Sep 21 00:07:56 1995 Tatu Ylonen + + * auth-rhosts.c: Restructured rhosts authentication code. + Hosts.equiv now has same format as .rhosts: user names are allowed. + + * Added support for the Intel Paragon. + + * sshd.c: Don't use X11 forwarding with spoofing if no xauth + program. Changed configure.in to not define XAUTH_PATH if + there is no xauth program. + + * ssh-1.2.7 + + * sshd.c: Rewrote the code to build the environment. Now also reads + /etc/environment. + + * sshd.c: Fixed problems in libwrap code. --with-libwrap now + takes optional library name/path. + + * ssh-1.2.6 + + * Define USE_PIPES by default. + + * Added support for Univel Unixware and MachTen. + + * Added IgnoreRhosts server option. + + * Added USE_STRLEN_FOR_AF_UNIX; it is needed at least on MachTen. + +Wed Sep 20 02:41:02 1995 Tatu Ylonen + + * sshd.c (do_child): don't call packet_close when /etc/nologin, + because packet_close does shutdown, and the message does not get + sent. + + * pty.c (pty_allocate): Push ttcompat streams module. + + * randoms.c (random_acquire_light_environmental_noise): Don't use + the second argument to gettimeofday as it is not supported on + all systems. + + * login.c (record_login): Added NULL second argument to gettimeofday. + +Tue Sep 19 13:25:48 1995 Tatu Ylonen + + * fixed pclose wait() in sshd key regeneration (now only collects + easily available noise). + + * configure.in: test for bsdi before bsd*. + + * ssh.c: Don't print "Connection closed" if -q. + +Wed Sep 13 04:19:52 1995 Tatu Ylonen + + * Released ssh-1.2.5. + + * Hopefully fixed "Waiting for forwarded connections to terminate" + message. + + * randoms.c, md5.c: Large modifications to make these work on Cray + (which has no 32 bit integer type). + + * Fixed a problem with forwarded connection closes not being + reported immediately. + + * ssh.c: fixed rhosts authentication (broken by uid-swapping). + + * scp.c: Don't use -l if server user not specified (it made + setting User in the configuration file not work). + + * configure.in: don't use -pipe on BSDI. + + * randoms.c: Major modifications to make it work without 32 bit + integers (e.g. Cray). + + * md5.c: Major modifications to make it work without 32 bit + integers (e.g. Cray). + + * Eliminated HPSUX_BROKEN_PTYS. The code is now enabled by + default on all systems. + +Mon Sep 11 00:53:12 1995 Tatu Ylonen + + * sshd.c: don't include sshd pathname in log messages. + + * Added libwrap stuff (includes support for identd). + + * Added OSF/1 C2 extended security stuff. + + * Fixed interactions between getuid() and uid-swap stuff. + +Sun Sep 10 00:29:27 1995 Tatu Ylonen + + * serverloop.c: Don't send stdout data to client until after a few + milliseconds if there is very little data. This is because some + systems give data from pty one character at a time, which would + multiply data size by about 16. + + * serverloop.c: Moved server do_session to a separate file and + renamed it server_loop. Split it into several functions and + partially rewrote it. Fixed "cat /etc/termcap | ssh foo cat" hangup. + + * Screwed up something while checking stuff in under cvs. No harm, + but bogus log entries... + +Sat Sep 9 02:24:51 1995 Tatu Ylonen + + * minfd.c (_get_permanent_fd): Use SHELL environment variable. + + * channels.c (x11_create_display_inet): Created + HPSUX_NONSTANDARD_X11_KLUDGE; it causes DISPLAY to contain the + IP address of the host instead of the name, because HPSUX uses + some magic shared memory communication for local connections. + + * Changed SIGHUP processing in server; it should now work multiple + times. + + * Added length limits in many debug/log/error/fatal calls just in + case. + + * login.c (get_last_login_time): Fixed location of lastlog. + + * Rewrote all uid-swapping code. New files uidswap.h, uidswap.c. + + * Fixed several security problems involving chmod and chgrp (race + conditions). Added warnings about dubious modes for /tmp/.X11-unix. + +Fri Sep 8 20:03:36 1995 Tatu Ylonen + + * Changed readconf.c to never display anything from the config + file. This should now be prevented otherwise, but let's play safe. + + * log-server.c: Use %.500s in syslog() just to be sure (they + should already be shorter than 1024 though). + + * sshd.c: Moved setuid in child a little earlier (just to be + conservative, there was no security problem that I could detect). + + * README, INSTALL: Added info about mailing list and WWW page. + + * sshd.c: Added code to use SIGCHLD and wait zombies immediately. + + * Merged patch to set ut_addr in utmp. + + * Created ChangeLog and added it to Makefile.in. + + * Use read_passphrase instead of getpass(). + + * Added SSH_FALLBACK_CIPHER. Fixed a bug in default cipher + selection (IDEA used to be selected even if not supported by the + server). + + * Use no encryption for key files if empty passphrase. + + * Added section about --without-idea in INSTALL. + + * Version 1.2.0 was released a couple of days ago. + diff --git a/ChangeLog.linux b/ChangeLog.linux new file mode 100644 index 00000000..a28e577a --- /dev/null +++ b/ChangeLog.linux @@ -0,0 +1,20 @@ +19991027 + - Adapted PAM patch. + - Released 1.0pre2 + + - Excised my buggy replacements for strlcpy and mkdtemp + - Imported correct OpenBSD strlcpy and mkdtemp routines. + - Reduced arc4random_stir entropy read to 32 bytes (256 bits) + - Picked up correct version number from OpenBSD + - Added sshd.pam PAM configuration file + - Added sshd.init Redhat init script + - Added openssh.spec RPM spec file + - Released 1.2pre3 + +19991026 + - Fixed include paths of OpenSSL functions + - Use OpenSSL MD5 routines + - Imported RC4 code from nanocrypt + - Wrote replacements for OpenBSD arc4random* functions + - Wrote replacements for strlcpy and mkdtemp + - Released 1.0pre1 diff --git a/Makefile b/Makefile new file mode 100644 index 00000000..668900c3 --- /dev/null +++ b/Makefile @@ -0,0 +1,13 @@ +# $OpenBSD: Makefile,v 1.5 1999/10/25 20:27:26 markus Exp $ + +.include + +SUBDIR= lib ssh sshd ssh-add ssh-keygen ssh-agent scp + +distribution: + install -C -o root -g wheel -m 0644 ${.CURDIR}/ssh_config \ + ${DESTDIR}/etc/ssh_config + install -C -o root -g wheel -m 0644 ${.CURDIR}/sshd_config \ + ${DESTDIR}/etc/sshd_config + +.include diff --git a/Makefile.GNU b/Makefile.GNU new file mode 100644 index 00000000..f36bdb3d --- /dev/null +++ b/Makefile.GNU @@ -0,0 +1,50 @@ +OPT_FLAGS=-g +CFLAGS=$(OPT_FLAGS) -Wall -DETCDIR=\"/etc/ssh\" -DHAVE_PAM +TARGETS=bin/libssh.a bin/ssh bin/sshd bin/ssh-add bin/ssh-keygen bin/ssh-agent bin/scp +LFLAGS=-L./bin +LIBS=-lssh -lcrypto -lz -lutil -lpam -ldl +AR=ar +RANLIB=ranlib + +OBJS= authfd.o authfile.o auth-passwd.o auth-rhosts.o auth-rh-rsa.o \ + auth-rsa.o bufaux.o buffer.o canohost.o channels.o cipher.o \ + clientloop.o compress.o crc32.o deattack.o hostfile.o \ + log-client.o login.o log-server.o match.o mpaux.o packet.o pty.o \ + readconf.o readpass.o rsa.o servconf.o serverloop.o \ + sshconnect.o tildexpand.o ttymodes.o uidswap.o xmalloc.o \ + helper.o mktemp.o strlcpy.o rc4.o + +all: $(OBJS) $(TARGETS) + +bin/libssh.a: authfd.o authfile.o bufaux.o buffer.o canohost.o channels.o cipher.o compat.o compress.o crc32.o deattack.o hostfile.o match.o mpaux.o nchan.o packet.o readpass.o rsa.o tildexpand.o ttymodes.o uidswap.o xmalloc.o helper.o rc4.o mktemp.o strlcpy.o + [ -d bin ] || mkdir bin + $(AR) rv $@ $^ + $(RANLIB) $@ + +bin/ssh: ssh.o sshconnect.o log-client.o readconf.o clientloop.o + [ -d bin ] || mkdir bin + $(CC) -o $@ $^ $(LFLAGS) $(LIBS) + +bin/sshd: sshd.o auth-rhosts.o auth-passwd.o auth-rsa.o auth-rh-rsa.o pty.o log-server.o login.o servconf.o serverloop.o + [ -d bin ] || mkdir bin + $(CC) -o $@ $^ $(LFLAGS) $(LIBS) + +bin/scp: scp.o + [ -d bin ] || mkdir bin + $(CC) -o $@ $^ $(LFLAGS) $(LIBS) + +bin/ssh-add: ssh-add.o log-client.o + [ -d bin ] || mkdir bin + $(CC) -o $@ $^ $(LFLAGS) $(LIBS) + +bin/ssh-agent: ssh-agent.o log-client.o + [ -d bin ] || mkdir bin + $(CC) -o $@ $^ $(LFLAGS) $(LIBS) + +bin/ssh-keygen: ssh-keygen.o log-client.o + [ -d bin ] || mkdir bin + $(CC) -o $@ $^ $(LFLAGS) $(LIBS) + +clean: + rm -f *.o core bin/* + diff --git a/Makefile.inc b/Makefile.inc new file mode 100644 index 00000000..fddf3da2 --- /dev/null +++ b/Makefile.inc @@ -0,0 +1,11 @@ +CFLAGS+= -I${.CURDIR}/.. + +.include + +.if exists(${.CURDIR}/../lib/${__objdir}) +LDADD+= -L${.CURDIR}/../lib/${__objdir} -lssh +DPADD+= ${.CURDIR}/../lib/${__objdir}/libssh.a +.else +LDADD+= -L${.CURDIR}/../lib -lssh +DPADD+= ${.CURDIR}/../lib/libssh.a +.endif diff --git a/OVERVIEW b/OVERVIEW new file mode 100644 index 00000000..a8b67e4e --- /dev/null +++ b/OVERVIEW @@ -0,0 +1,164 @@ +This document is inteded for those who wish to read the ssh source +code. This tries to give an overview of the structure of the code. + +Copyright (c) 1995 Tatu Ylonen +Updated 17 Nov 1995. +Updated 19 Oct 1999 for OpenSSH-1.2 + +The software consists of ssh (client), sshd (server), scp, sdist, and +the auxiliary programs ssh-keygen, ssh-agent, ssh-add, and +make-ssh-known-hosts. The main program for each of these is in a .c +file with the same name. + +There are some subsystems/abstractions that are used by a number of +these programs. + + Buffer manipulation routines + + - These provide an arbitrary size buffer, where data can be appended. + Data can be consumed from either end. The code is used heavily + throughout ssh. The basic buffer manipulation functions are in + buffer.c (header buffer.h), and additional code to manipulate specific + data types is in bufaux.c. + + Compression Library + + - Ssh uses the GNU GZIP compression library (ZLIB). + + Encryption/Decryption + + - Ssh contains several encryption algorithms. These are all + accessed through the cipher.h interface. The interface code is + in cipher.c, and the implementations are in libc. + + Multiple Precision Integer Library + + - Uses the SSLeay BIGNUM sublibrary. + - Some auxiliary functions for mp-int manipulation are in mpaux.c. + + Random Numbers + + - Uses arc4random() and such. + + RSA key generation, encryption, decryption + + - Ssh uses the RSA routines in libssl. + + RSA key files + + - RSA keys are stored in files with a special format. The code to + read/write these files is in authfile.c. The files are normally + encrypted with a passphrase. The functions to read passphrases + are in readpass.c (the same code is used to read passwords). + + Binary packet protocol + + - The ssh binary packet protocol is implemented in packet.c. The + code in packet.c does not concern itself with packet types or their + execution; it contains code to build packets, to receive them and + extract data from them, and the code to compress and/or encrypt + packets. CRC code comes from crc32.c. + + - The code in packet.c calls the buffer manipulation routines + (buffer.c, bufaux.c), compression routines (compress.c, zlib), + and the encryption routines. + + X11, TCP/IP, and Agent forwarding + + - Code for various types of channel forwarding is in channels.c. + The file defines a generic framework for arbitrary communication + channels inside the secure channel, and uses this framework to + implement X11 forwarding, TCP/IP forwarding, and authentication + agent forwarding. + The new, Protocol 1.5, channel close implementation is in nchan.c + + Authentication agent + + - Code to communicate with the authentication agent is in authfd.c. + + Authentication methods + + - Code for various authentication methods resides in auth-*.c + (auth-passwd.c, auth-rh-rsa.c, auth-rhosts.c, auth-rsa.c). This + code is linked into the server. The routines also manipulate + known hosts files using code in hostfile.c. Code in canohost.c + is used to retrieve the canonical host name of the remote host. + Code in match.c is used to match host names. + + - In the client end, authentication code is in sshconnect.c. It + reads Passwords/passphrases using code in readpass.c. It reads + RSA key files with authfile.c. It communicates the + authentication agent using authfd.c. + + The ssh client + + - The client main program is in ssh.c. It first parses arguments + and reads configuration (readconf.c), then calls ssh_connect (in + sshconnect.c) to open a connection to the server (possibly via a + proxy), and performs authentication (ssh_login in sshconnect.c). + It then makes any pty, forwarding, etc. requests. It may call + code in ttymodes.c to encode current tty modes. Finally it + calls client_loop in clientloop.c. This does the real work for + the session. + + - The client is suid root. It tries to temporarily give up this + rights while reading the configuration data. The root + privileges are only used to make the connection (from a + privileged socket). Any extra privileges are dropped before + calling ssh_login. + + Pseudo-tty manipulation and tty modes + + - Code to allocate and use a pseudo tty is in pty.c. Code to + encode and set terminal modes is in ttymodes.c. + + Logging in (updating utmp, lastlog, etc.) + + - The code to do things that are done when a user logs in are in + login.c. This includes things such as updating the utmp, wtmp, + and lastlog files. Some of the code is in sshd.c. + + Writing to the system log and terminal + + - The programs use the functions fatal(), log(), debug(), error() + in many places to write messages to system log or user's + terminal. The implementation that logs to system log is in + log-server.c; it is used in the server program. The other + programs use an implementation that sends output to stderr; it + is in log-client.c. The definitions are in ssh.h. + + The sshd server (daemon) + + - The sshd daemon starts by processing arguments and reading the + configuration file (servconf.c). It then reads the host key, + starts listening for connections, and generates the server key. + The server key will be regenerated every hour by an alarm. + + - When the server receives a connection, it forks, disables the + regeneration alarm, and starts communicating with the client. + They first perform identification string exchange, then + negotiate encryption, then perform authentication, preparatory + operations, and finally the server enters the normal session + mode by calling server_loop in serverloop.c. This does the real + work, calling functions in other modules. + + - The code for the server is in sshd.c. It contains a lot of + stuff, including: + - server main program + - waiting for connections + - processing new connection + - authentication + - preparatory operations + - building up the execution environment for the user program + - starting the user program. + + Auxiliary files + + - There are several other files in the distribution that contain + various auxiliary routines: + ssh.h the main header file for ssh (various definitions) + getput.h byte-order independent storage of integers + includes.h includes most system headers. Lots of #ifdefs. + tildexpand.c expand tilde in file names + uidswap.c uid-swapping + xmalloc.c "safe" malloc routines diff --git a/README b/README new file mode 100644 index 00000000..ed360844 --- /dev/null +++ b/README @@ -0,0 +1,563 @@ +Ssh (Secure Shell) is a program to log into another computer over a +network, to execute commands in a remote machine, and to move files +from one machine to another. It provides strong authentication and +secure communications over insecure channels. It is inteded as a +replacement for rlogin, rsh, rcp, and rdist. + +See the file INSTALL for installation instructions. See COPYING for +license terms and other legal issues. See RFC for a description of +the protocol. There is a WWW page for ssh; see http://www.cs.hut.fi/ssh. + +This file has been updated to match ssh-1.2.12. + + +FEATURES + + o Strong authentication. Closes several security holes (e.g., IP, + routing, and DNS spoofing). New authentication methods: .rhosts + together with RSA based host authentication, and pure RSA + authentication. + + o Improved privacy. All communications are automatically and + transparently encrypted. RSA is used for key exchange, and a + conventional cipher (normally IDEA, DES, or triple-DES) for + encrypting the session. Encryption is started before + authentication, and no passwords or other information is + transmitted in the clear. Encryption is also used to protect + against spoofed packets. + + o Secure X11 sessions. The program automatically sets DISPLAY on + the server machine, and forwards any X11 connections over the + secure channel. Fake Xauthority information is automatically + generated and forwarded to the remote machine; the local client + automatically examines incoming X11 connections and replaces the + fake authorization data with the real data (never telling the + remote machine the real information). + + o Arbitrary TCP/IP ports can be redirected through the encrypted channel + in both directions (e.g., for e-cash transactions). + + o No retraining needed for normal users; everything happens + automatically, and old .rhosts files will work with strong + authentication if administration installs host key files. + + o Never trusts the network. Minimal trust on the remote side of + the connection. Minimal trust on domain name servers. Pure RSA + authentication never trusts anything but the private key. + + o Client RSA-authenticates the server machine in the beginning of + every connection to prevent trojan horses (by routing or DNS + spoofing) and man-in-the-middle attacks, and the server + RSA-authenticates the client machine before accepting .rhosts or + /etc/hosts.equiv authentication (to prevent DNS, routing, or + IP-spoofing). + + o Host authentication key distribution can be centrally by the + administration, automatically when the first connection is made + to a machine (the key obtained on the first connection will be + recorded and used for authentication in the future), or manually + by each user for his/her own use. The central and per-user host + key repositories are both used and complement each other. Host + keys can be generated centrally or automatically when the software + is installed. Host authentication keys are typically 1024 bits. + + o Any user can create any number of user authentication RSA keys for + his/her own use. Each user has a file which lists the RSA public + keys for which proof of possession of the corresponding private + key is accepted as authentication. User authentication keys are + typically 1024 bits. + + o The server program has its own server RSA key which is + automatically regenerated every hour. This key is never saved in + any file. Exchanged session keys are encrypted using both the + server key and the server host key. The purpose of the separate + server key is to make it impossible to decipher a captured session by + breaking into the server machine at a later time; one hour from + the connection even the server machine cannot decipher the session + key. The key regeneration interval is configurable. The server + key is normally 768 bits. + + o An authentication agent, running in the user's laptop or local + workstation, can be used to hold the user's RSA authentication + keys. Ssh automatically forwards the connection to the + authentication agent over any connections, and there is no need to + store the RSA authentication keys on any machine in the network + (except the user's own local machine). The authentication + protocols never reveal the keys; they can only be used to verify + that the user's agent has a certain key. Eventually the agent + could rely on a smart card to perform all authentication + computations. + + o The software can be installed and used (with restricted + functionality) even without root privileges. + + o The client is customizable in system-wide and per-user + configuration files. Most aspects of the client's operation can + be configured. Different options can be specified on a per-host basis. + + o Automatically executes conventional rsh (after displaying a + warning) if the server machine is not running sshd. + + o Optional compression of all data with gzip (including forwarded X11 + and TCP/IP port data), which may result in significant speedups on + slow connections. + + o Complete replacement for rlogin, rsh, and rcp. + + +WHY TO USE SECURE SHELL + +Currently, almost all communications in computer networks are done +without encryption. As a consequence, anyone who has access to any +machine connected to the network can listen in on any communication. +This is being done by hackers, curious administrators, employers, +criminals, industrial spies, and governments. Some networks leak off +enough electromagnetic radiation that data may be captured even from a +distance. + +When you log in, your password goes in the network in plain +text. Thus, any listener can then use your account to do any evil he +likes. Many incidents have been encountered worldwide where crackers +have started programs on workstations without the owners knowledge +just to listen to the network and collect passwords. Programs for +doing this are available on the Internet, or can be built by a +competent programmer in a few hours. + +Any information that you type or is printed on your screen can be +monitored, recorded, and analyzed. For example, an intruder who has +penetrated a host connected to a major network can start a program +that listens to all data flowing in the network, and whenever it +encounters a 16-digit string, it checks if it is a valid credit card +number (using the check digit), and saves the number plus any +surrounding text (to catch expiration date and holder) in a file. +When the intruder has collected a few thousand credit card numbers, he +makes smallish mail-order purchases from a few thousand stores around +the world, and disappears when the goods arrive but before anyone +suspects anything. + +Businesses have trade secrets, patent applications in preparation, +pricing information, subcontractor information, client data, personnel +data, financial information, etc. Currently, anyone with access to +the network (any machine on the network) can listen to anything that +goes in the network, without any regard to normal access restrictions. + +Many companies are not aware that information can so easily be +recovered from the network. They trust that their data is safe +since nobody is supposed to know that there is sensitive information +in the network, or because so much other data is transferred in the +network. This is not a safe policy. + +Individual persons also have confidential information, such as +diaries, love letters, health care documents, information about their +personal interests and habits, professional data, job applications, +tax reports, political documents, unpublished manuscripts, etc. + +One should also be aware that economical intelligence and industrial +espionage has recently become a major priority of the intelligence +agencies of major governments. President Clinton recently assigned +economical espionage as the primary task of the CIA, and the French +have repeatedly been publicly boasting about their achievements on +this field. + + +There is also another frightening aspect about the poor security of +communications. Computer storage and analysis capability has +increased so much that it is feasible for governments, major +companies, and criminal organizations to automatically analyze, +identify, classify, and file information about millions of people over +the years. Because most of the work can be automated, the cost of +collecting this information is getting very low. + +Government agencies may be able to monitor major communication +systems, telephones, fax, computer networks, etc., and passively +collect huge amounts of information about all people with any +significant position in the society. Most of this information is not +sensitive, and many people would say there is no harm in someone +getting that information. However, the information starts to get +sensitive when someone has enough of it. You may not mind someone +knowing what you bought from the shop one random day, but you might +not like someone knowing every small thing you have bought in the last +ten years. + +If the government some day starts to move into a more totalitarian +direction (one should remember that Nazi Germany was created by +democratic elections), there is considerable danger of an ultimate +totalitarian state. With enough information (the automatically +collected records of an individual can be manually analyzed when the +person becomes interesting), one can form a very detailed picture of +the individual's interests, opinions, beliefs, habits, friends, +lovers, weaknesses, etc. This information can be used to 1) locate +any persons who might oppose the new system 2) use deception to +disturb any organizations which might rise against the government 3) +eliminate difficult individuals without anyone understanding what +happened. Additionally, if the government can monitor communications +too effectively, it becomes too easy to locate and eliminate any +persons distributing information contrary to the official truth. + +Fighting crime and terrorism are often used as grounds for domestic +surveillance and restricting encryption. These are good goals, but +there is considerable danger that the surveillance data starts to get +used for questionable purposes. I find that it is better to tolerate +a small amount of crime in the society than to let the society become +fully controlled. I am in favor of a fairly strong state, but the +state must never get so strong that people become unable to spread +contra-offical information and unable to overturn the government if it +is bad. The danger is that when you notice that the government is +too powerful, it is too late. Also, the real power may not be where +the official government is. + +For these reasons (privacy, protecting trade secrets, and making it +more difficult to create a totalitarian state), I think that strong +cryptography should be integrated to the tools we use every day. +Using it causes no harm (except for those who wish to monitor +everything), but not using it can cause huge problems. If the society +changes in undesirable ways, then it will be to late to start +encrypting. + +Encryption has had a "military" or "classified" flavor to it. There +are no longer any grounds for this. The military can and will use its +own encryption; that is no excuse to prevent the civilians from +protecting their privacy and secrets. Information on strong +encryption is available in every major bookstore, scientific library, +and patent office around the world, and strong encryption software is +available in every country on the Internet. + +Some people would like to make it illegal to use encryption, or to +force people to use encryption that governments can break. This +approach offers no protection if the government turns bad. Also, the +"bad guys" will be using true strong encryption anyway. Good +encryption techniques are too widely known to make them disappear. +Thus, any "key escrow encryption" or other restrictions will only help +monitor ordinary people and petty criminals. It does not help against +powerful criminals, terrorists, or espionage, because they will know +how to use strong encryption anyway. (One source for internationally +available encryption software is http://www.cs.hut.fi/crypto.) + + +OVERVIEW OF SECURE SHELL + +The software consists of a number of programs. + + sshd Server program run on the server machine. This + listens for connections from client machines, and + whenever it receives a connection, it performs + authentication and starts serving the client. + + ssh This is the client program used to log into another + machine or to execute commands on the other machine. + "slogin" is another name for this program. + + scp Securely copies files from one machine to another. + + ssh-keygen Used to create RSA keys (host keys and user + authentication keys). + + ssh-agent Authentication agent. This can be used to hold RSA + keys for authentication. + + ssh-add Used to register new keys with the agent. + + make-ssh-known-hosts + Used to create the /etc/ssh_known_hosts file. + + +Ssh is the program users normally use. It is started as + + ssh host + +or + + ssh host command + +The first form opens a new shell on the remote machine (after +authentication). The latter form executes the command on the remote +machine. + +When started, the ssh connects sshd on the server machine, verifies +that the server machine really is the machine it wanted to connect, +exchanges encryption keys (in a manner which prevents an outside +listener from getting the keys), performs authentication using .rhosts +and /etc/hosts.equiv, RSA authentication, or conventional password +based authentication. The server then (normally) allocates a +pseudo-terminal and starts an interactive shell or user program. + +The TERM environment variable (describing the type of the user's +terminal) is passed from the client side to the remote side. Also, +terminal modes will be copied from the client side to the remote side +to preserve user preferences (e.g., the erase character). + +If the DISPLAY variable is set on the client side, the server will +create a dummy X server and set DISPLAY accordingly. Any connections +to the dummy X server will be forwarded through the secure channel, +and will be made to the real X server from the client side. An +arbitrary number of X programs can be started during the session, and +starting them does not require anything special from the user. (Note +that the user must not manually set DISPLAY, because then it would +connect directly to the real display instead of going through the +encrypted channel). This behavior can be disabled in the +configuration file or by giving the -x option to the client. + +Arbitrary IP ports can be forwarded over the secure channel. The +program then creates a port on one side, and whenever a connection is +opened to this port, it will be passed over the secure channel, and a +connection will be made from the other side to a specified host:port +pair. Arbitrary IP forwarding must always be explicitly requested, +and cannot be used to forward privileged ports (unless the user is +root). It is possible to specify automatic forwards in a per-user +configuration file, for example to make electronic cash systems work +securely. + +If there is an authentication agent on the client side, connection to +it will be automatically forwarded to the server side. + +For more infomation, see the manual pages ssh(1), sshd(8), scp(1), +ssh-keygen(1), ssh-agent(1), ssh-add(1), and make-ssh-known-hosts(1) +included in this distribution. + + +X11 CONNECTION FORWARDING + +X11 forwarding serves two purposes: it is a convenience to the user +because there is no need to set the DISPLAY variable, and it provides +encrypted X11 connections. I cannot think of any other easy way to +make X11 connections encrypted; modifying the X server, clients or +libraries would require special work for each machine, vendor and +application. Widely used IP-level encryption does not seem likely for +several years. Thus what we have left is faking an X server on the +same machine where the clients are run, and forwarding the connections +to a real X server over the secure channel. + +X11 forwarding works as follows. The client extracts Xauthority +information for the server. It then creates random authorization +data, and sends the random data to the server. The server allocates +an X11 display number, and stores the (fake) Xauthority data for this +display. Whenever an X11 connection is opened, the server forwards +the connection over the secure channel to the client, and the client +parses the first packet of the X11 protocol, substitutes real +authentication data for the fake data (if the fake data matched), and +forwards the connection to the real X server. + +If the display does not have Xauthority data, the server will create a +unix domain socket in /tmp/.X11-unix, and use the unix domain socket +as the display. No authentication information is forwarded in this +case. X11 connections are again forwarded over the secure channel. +To the X server the connections appear to come from the client +machine, and the server must have connections allowed from the local +machine. Using authentication data is always recommended because not +using it makes the display insecure. If XDM is used, it automatically +generates the authentication data. + +One should be careful not to use "xin" or "xstart" or other similar +scripts that explicitly set DISPLAY to start X sessions in a remote +machine, because the connection will then not go over the secure +channel. The recommended way to start a shell in a remote machine is + + xterm -e ssh host & + +and the recommended way to execute an X11 application in a remote +machine is + + ssh -n host emacs & + +If you need to type a password/passphrase for the remote machine, + + ssh -f host emacs + +may be useful. + + + +RSA AUTHENTICATION + +RSA authentication is based on public key cryptograpy. The idea is +that there are two encryption keys, one for encryption and another for +decryption. It is not possible (on human timescale) to derive the +decryption key from the encryption key. The encryption key is called +the public key, because it can be given to anyone and it is not +secret. The decryption key, on the other hand, is secret, and is +called the private key. + +RSA authentication is based on the impossibility of deriving the +private key from the public key. The public key is stored on the +server machine in the user's $HOME/.ssh/authorized_keys file. The +private key is only kept on the user's local machine, laptop, or other +secure storage. Then the user tries to log in, the client tells the +server the public key that the user wishes to use for authentication. +The server then checks if this public key is admissible. If so, it +generates a 256 bit random number, encrypts it with the public key, +and sends the value to the client. The client then decrypts the +number with its private key, computes a 128 bit MD5 checksum from the +resulting data, and sends the checksum back to the server. (Only a +checksum is sent to prevent chosen-plaintext attacks against RSA.) +The server checks computes a checksum from the correct data, +and compares the checksums. Authentication is accepted if the +checksums match. (Theoretically this indicates that the client +only probably knows the correct key, but for all practical purposes +there is no doubt.) + +The RSA private key can be protected with a passphrase. The +passphrase can be any string; it is hashed with MD5 to produce an +encryption key for IDEA, which is used to encrypt the private part of +the key file. With passphrase, authorization requires access to the key +file and the passphrase. Without passphrase, authorization only +depends on possession of the key file. + +RSA authentication is the most secure form of authentication supported +by this software. It does not rely on the network, routers, domain +name servers, or the client machine. The only thing that matters is +access to the private key. + +All this, of course, depends on the security of the RSA algorithm +itself. RSA has been widely known since about 1978, and no effective +methods for breaking it are known if it is used properly. Care has +been taken to avoid the well-known pitfalls. Breaking RSA is widely +believed to be equivalent to factoring, which is a very hard +mathematical problem that has received considerable public research. +So far, no effective methods are known for numbers bigger than about +512 bits. However, as computer speeds and factoring methods are +increasing, 512 bits can no longer be considered secure. The +factoring work is exponential, and 768 or 1024 bits are widely +considered to be secure in the near future. + + +RHOSTS AUTHENTICATION + +Conventional .rhosts and hosts.equiv based authentication mechanisms +are fundamentally insecure due to IP, DNS (domain name server) and +routing spoofing attacks. Additionally this authentication method +relies on the integrity of the client machine. These weaknesses is +tolerable, and been known and exploited for a long time. + +Ssh provides an improved version of these types of authentication, +because they are very convenient for the user (and allow easy +transition from rsh and rlogin). It permits these types of +authentication, but additionally requires that the client host be +authenticated using RSA. + +The server has a list of host keys stored in /etc/ssh_known_host, and +additionally each user has host keys in $HOME/.ssh/known_hosts. Ssh +uses the name servers to obtain the canonical name of the client host, +looks for its public key in its known host files, and requires the +client to prove that it knows the private host key. This prevents IP +and routing spoofing attacks (as long as the client machine private +host key has not been compromized), but is still vulnerable to DNS +attacks (to a limited extent), and relies on the integrity of the +client machine as to who is requesting to log in. This prevents +outsiders from attacking, but does not protect against very powerful +attackers. If maximal security is desired, only RSA authentication +should be used. + +It is possible to enable conventional .rhosts and /etc/hosts.equiv +authentication (without host authentication) at compile time by giving +the option --with-rhosts to configure. However, this is not +recommended, and is not done by default. + +These weaknesses are present in rsh and rlogin. No improvement in +security will be obtained unless rlogin and rsh are completely +disabled (commented out in /etc/inetd.conf). This is highly +recommended. + + +WEAKEST LINKS IN SECURITY + +One should understand that while this software may provide +cryptographically secure communications, it may be easy to +monitor the communications at their endpoints. + +Basically, anyone with root access on the local machine on which you +are running the software may be able to do anything. Anyone with root +access on the server machine may be able to monitor your +communications, and a very talented root user might even be able to +send his/her own requests to your authentication agent. + +One should also be aware that computers send out electromagnetic +radition that can sometimes be picked up hundreds of meters away. +Your keyboard is particularly easy to listen to. The image on your +monitor might also be seen on another monitor in a van parked behind +your house. + +Beware that unwanted visitors might come to your home or office and +use your machine while you are away. They might also make +modifications or install bugs in your hardware or software. + +Beware that the most effective way for someone to decrypt your data +may be with a rubber hose. + + +LEGAL ISSUES + +As far as I am concerned, anyone is permitted to use this software +freely. However, see the file COPYING for detailed copying, +licensing, and distribution information. + +In some countries, particularly France, Russia, Iraq, and Pakistan, +it may be illegal to use any encryption at all without a special +permit, and the rumor has it that you cannot get a permit for any +strong encryption. + +This software may be freely imported into the United States; however, +the United States Government may consider re-exporting it a criminal +offence. + +Note that any information and cryptographic algorithms used in this +software are publicly available on the Internet and at any major +bookstore, scientific library, or patent office worldwide. + +THERE IS NO WARRANTY FOR THIS PROGRAM. Please consult the file +COPYING for more information. + + +MAILING LISTS AND OTHER INFORMATION + +There is a mailing list for ossh. It is ossh@sics.se. If you would +like to join, send a message to majordomo@sics.se with "subscribe +ssh" in body. + +The WWW home page for ssh is http://www.cs.hut.fi/ssh. It contains an +archive of the mailing list, and detailed information about new +releases, mailing lists, and other relevant issues. + +Bug reports should be sent to ossh-bugs@sics.se. + + +ABOUT THE AUTHOR + +This software was written by Tatu Ylonen . I work as a +researcher at Helsinki University of Technology, Finland. For more +information, see http://www.cs.hut.fi/~ylo/. My PGP public key is +available via finger from ylo@cs.hut.fi and from the key servers. I +prefer PGP encrypted mail. + +The author can be contacted via ordinary mail at + Tatu Ylonen + Helsinki University of Technology + Otakaari 1 + FIN-02150 ESPOO + Finland + + Fax. +358-0-4513293 + + +ACKNOWLEDGEMENTS + +I thank Tero Kivinen, Timo Rinne, Janne Snabb, and Heikki Suonsivu for +their help and comments in the design, implementation and porting of +this software. I also thank numerous contributors, including but not +limited to Walker Aumann, Jurgen Botz, Hans-Werner Braun, Stephane +Bortzmeyer, Adrian Colley, Michael Cooper, David Dombek, Jerome +Etienne, Bill Fithen, Mark Fullmer, Bert Gijsbers, Andreas Gustafsson, +Michael Henits, Steve Johnson, Thomas Koenig, Felix Leitner, Gunnar +Lindberg, Andrew Macpherson, Marc Martinec, Paul Mauvais, Donald +McKillican, Leon Mlakar, Robert Muchsel, Mark Treacy, Bryan +O'Sullivan, Mikael Suokas, Ollivier Robert, Jakob Schlyter, Tomasz +Surmacz, Alvar Vinacua, Petri Virkkula, Michael Warfield, and +Cristophe Wolfhugel. + +Thanks also go to Philip Zimmermann, whose PGP software and the +associated legal battle provided inspiration, motivation, and many +useful techniques, and to Bruce Schneier whose book Applied +Cryptography has done a great service in widely distributing knowledge +about cryptographic methods. + + +Copyright (c) 1995 Tatu Ylonen, Espoo, Finland. diff --git a/README.openssh b/README.openssh new file mode 100644 index 00000000..02cb3c60 --- /dev/null +++ b/README.openssh @@ -0,0 +1,44 @@ +This is a Linux port of OpenBSD's excellent OpenSSH. + +OpenSSH is based on the last free version of Tatu Ylonen's SSH with all +patent-encumbered algorithms removed, all known security bugs fixed, new +features reintroduced and many other clean-ups. + +This Linux port basically consists of a few fixes to deal with the way that +OpenSSL is usually installed on Linux systems, a few replacements for +OpenBSD library functions and the introduction of partial PAM support. + +The PAM support is less than optimal - it is only used when password +authentication is requested, so things like pam_limits will not apply if a +user authenticates with a RSA key. OTOH this is exactly the level of support +that the popular Linux SSH packages have. Perhaps a PAM hacker can rectify +this? + +All new code is released under a XFree style license, which is very liberal. +This code is released with no warranties of any kind, neither I nor my +employer (Internet Business Solutions) will take any responsibility for +any loss, damage or liability arising from the use or abuse of this software. + +OpenSSH depends on Zlib, OpenSSL and PAM. Use the Makefile.GNU to build it. + +Damien Miller +Internet Business Solutions + + +Credits - + +The OpenBSD team +'jonchen' - the original author of PAM support of SSH + +Miscellania - + +This version of SSH is based upon code retrieved from the OpenBSD CVS +repository on 1999-10-26, which in turn was based on the last free +version of SSH released by Tatu Ylonen. + +Code in helper.[ch] is Copyright 1999 Internet Business Solutions and +is released under a X11-style license (see source file for details). + +(A)RC4 code in rc4.[ch] is Copyright 1999 Damien Miller. It too is +under a X11-style license (see source file for details). + diff --git a/RFC.nroff b/RFC.nroff new file mode 100644 index 00000000..8946ad24 --- /dev/null +++ b/RFC.nroff @@ -0,0 +1,1780 @@ +.\" -*- nroff -*- +.\" +.\" $Id$ +.\" +.pl 10.0i +.po 0 +.ll 7.2i +.lt 7.2i +.nr LL 7.2i +.nr LT 7.2i +.ds LF Ylonen +.ds RF FORMFEED[Page %] +.ds CF +.ds LH Internet-Draft +.ds RH 15 November 1995 +.ds CH SSH (Secure Shell) Remote Login Protocol +.na +.hy 0 +.in 0 +Network Working Group T. Ylonen +Internet-Draft Helsinki University of Technology +draft-ylonen-ssh-protocol-00.txt 15 November 1995 +Expires: 15 May 1996 + +.in 3 + +.ce +The SSH (Secure Shell) Remote Login Protocol + +.ti 0 +Status of This Memo + +This document is an Internet-Draft. Internet-Drafts are working +documents of the Internet Engineering Task Force (IETF), its areas, +and its working groups. Note that other groups may also distribute +working documents as Internet-Drafts. + +Internet-Drafts are draft documents valid for a maximum of six +months and may be updated, replaced, or obsoleted by other docu- +ments at any time. It is inappropriate to use Internet-Drafts as +reference material or to cite them other than as ``work in pro- +gress.'' + +To learn the current status of any Internet-Draft, please check the +``1id-abstracts.txt'' listing contained in the Internet- Drafts Shadow +Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), +munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or +ftp.isi.edu (US West Coast). + +The distribution of this memo is unlimited. + +.ti 0 +Introduction + +SSH (Secure Shell) is a program to log into another computer over a +network, to execute commands in a remote machine, and to move files +from one machine to another. It provides strong authentication and +secure communications over insecure networks. Its features include +the following: +.IP o +Closes several security holes (e.g., IP, routing, and DNS spoofing). +New authentication methods: .rhosts together with RSA [RSA] based host +authentication, and pure RSA authentication. +.IP o +All communications are automatically and transparently encrypted. +Encryption is also used to protect integrity. +.IP o +X11 connection forwarding provides secure X11 sessions. +.IP o +Arbitrary TCP/IP ports can be redirected over the encrypted channel +in both directions. +.IP o +Client RSA-authenticates the server machine in the beginning of every +connection to prevent trojan horses (by routing or DNS spoofing) and +man-in-the-middle attacks, and the server RSA-authenticates the client +machine before accepting .rhosts or /etc/hosts.equiv authentication +(to prevent DNS, routing, or IP spoofing). +.IP o +An authentication agent, running in the user's local workstation or +laptop, can be used to hold the user's RSA authentication keys. +.RT + +The goal has been to make the software as easy to use as possible for +ordinary users. The protocol has been designed to be as secure as +possible while making it possible to create implementations that +are easy to use and install. The sample implementation has a number +of convenient features that are not described in this document as they +are not relevant for the protocol. + + +.ti 0 +Overview of the Protocol + +The software consists of a server program running on a server machine, +and a client program running on a client machine (plus a few auxiliary +programs). The machines are connected by an insecure IP [RFC0791] +network (that can be monitored, tampered with, and spoofed by hostile +parties). + +A connection is always initiated by the client side. The server +listens on a specific port waiting for connections. Many clients may +connect to the same server machine. + +The client and the server are connected via a TCP/IP [RFC0793] socket +that is used for bidirectional communication. Other types of +transport can be used but are currently not defined. + +When the client connects the server, the server accepts the connection +and responds by sending back its version identification string. The +client parses the server's identification, and sends its own +identification. The purpose of the identification strings is to +validate that the connection was to the correct port, declare the +protocol version number used, and to declare the software version used +on each side (for debugging purposes). The identification strings are +human-readable. If either side fails to understand or support the +other side's version, it closes the connection. + +After the protocol identification phase, both sides switch to a packet +based binary protocol. The server starts by sending its host key +(every host has an RSA key used to authenticate the host), server key +(an RSA key regenerated every hour), and other information to the +client. The client then generates a 256 bit session key, encrypts it +using both RSA keys (see below for details), and sends the encrypted +session key and selected cipher type to the server. Both sides then +turn on encryption using the selected algorithm and key. The server +sends an encrypted confirmation message to the client. + +The client then authenticates itself using any of a number of +authentication methods. The currently supported authentication +methods are .rhosts or /etc/hosts.equiv authentication (disabled by +default), the same with RSA-based host authentication, RSA +authentication, and password authentication. + +After successful authentication, the client makes a number of requests +to prepare for the session. Typical requests include allocating a +pseudo tty, starting X11 [X11] or TCP/IP port forwarding, starting +authentication agent forwarding, and executing the shell or a command. + +When a shell or command is executed, the connection enters interactive +session mode. In this mode, data is passed in both directions, +new forwarded connections may be opened, etc. The interactive session +normally terminates when the server sends the exit status of the +program to the client. + + +The protocol makes several reservations for future extensibility. +First of all, the initial protocol identification messages include the +protocol version number. Second, the first packet by both sides +includes a protocol flags field, which can be used to agree on +extensions in a compatible manner. Third, the authentication and +session preparation phases work so that the client sends requests to +the server, and the server responds with success or failure. If the +client sends a request that the server does not support, the server +simply returns failure for it. This permits compatible addition of +new authentication methods and preparation operations. The +interactive session phase, on the other hand, works asynchronously and +does not permit the use of any extensions (because there is no easy +and reliable way to signal rejection to the other side and problems +would be hard to debug). Any compatible extensions to this phase must +be agreed upon during any of the earlier phases. + +.ti 0 +The Binary Packet Protocol + +After the protocol identification strings, both sides only send +specially formatted packets. The packet layout is as follows: +.IP o +Packet length: 32 bit unsigned integer, coded as four 8-bit bytes, msb +first. Gives the length of the packet, not including the length field +and padding. The maximum length of a packet (not including the length +field and padding) is 262144 bytes. +.IP o +Padding: 1-8 bytes of random data (or zeroes if not encrypting). The +amount of padding is (8 - (length % 8)) bytes (where % stands for the +modulo operator). The rationale for always having some random padding +at the beginning of each packet is to make known plaintext attacks +more difficult. +.IP o +Packet type: 8-bit unsigned byte. The value 255 is reserved for +future extension. +.IP o +Data: binary data bytes, depending on the packet type. The number of +data bytes is the "length" field minus 5. +.IP o +Check bytes: 32-bit crc, four 8-bit bytes, msb first. The crc is the +Cyclic Redundancy Check, with the polynomial 0xedb88320, of the +Padding, Packet type, and Data fields. The crc is computed before +any encryption. +.RT + +The packet, except for the length field, may be encrypted using any of +a number of algorithms. The length of the encrypted part (Padding + +Type + Data + Check) is always a multiple of 8 bytes. Typically the +cipher is used in a chained mode, with all packets chained together as +if it was a single data stream (the length field is never included in +the encryption process). Details of encryption are described below. + +When the session starts, encryption is turned off. Encryption is +enabled after the client has sent the session key. The encryption +algorithm to use is selected by the client. + + +.ti 0 +Packet Compression + +If compression is supported (it is an optional feature, see +SSH_CMSG_REQUEST_COMPRESSION below), the packet type and data fields +of the packet are compressed using the gzip deflate algorithm [GZIP]. +If compression is in effect, the packet length field indicates the +length of the compressed data, plus 4 for the crc. The amount of +padding is computed from the compressed data, so that the amount of +data to be encrypted becomes a multiple of 8 bytes. + +When compressing, the packets (type + data portions) in each direction +are compressed as if they formed a continuous data stream, with only the +current compression block flushed between packets. This corresponds +to the GNU ZLIB library Z_PARTIAL_FLUSH option. The compression +dictionary is not flushed between packets. The two directions are +compressed independently of each other. + + +.ti 0 +Packet Encryption + +The protocol supports several encryption methods. During session +initialization, the server sends a bitmask of all encryption methods +that it supports, and the client selects one of these methods. The +client also generates a 256-bit random session key (32 8-bit bytes) and +sends it to the server. + +The encryption methods supported by the current implementation, and +their codes are: +.TS +center; +l r l. +SSH_CIPHER_NONE 0 No encryption +SSH_CIPHER_IDEA 1 IDEA in CFB mode +SSH_CIPHER_DES 2 DES in CBC mode +SSH_CIPHER_3DES 3 Triple-DES in CBC mode +SSH_CIPHER_TSS 4 An experimental stream cipher +SSH_CIPHER_RC4 5 RC4 +.TE + +All implementations are required to support SSH_CIPHER_DES and +SSH_CIPHER_3DES. Supporting SSH_CIPHER_IDEA, SSH_CIPHER_RC4, and +SSH_CIPHER_NONE is recommended. Support for SSH_CIPHER_TSS is +optional (and it is not described in this document). Other ciphers +may be added at a later time; support for them is optional. + +For encryption, the encrypted portion of the packet is considered a +linear byte stream. The length of the stream is always a multiple of +8. The encrypted portions of consecutive packets (in the same +direction) are encrypted as if they were a continuous buffer (that is, +any initialization vectors are passed from the previous packet to the +next packet). Data in each direction is encrypted independently. +.IP SSH_CIPHER_DES +The key is taken from the first 8 bytes of the session key. The least +significant bit of each byte is ignored. This results in 56 bits of +key data. DES [DES] is used in CBC mode. The iv (initialization vector) is +initialized to all zeroes. +.IP SSH_CIPHER_3DES +The variant of triple-DES used here works as follows: there are three +independent DES-CBC ciphers, with independent initialization vectors. +The data (the whole encrypted data stream) is first encrypted with the +first cipher, then decrypted with the second cipher, and finally +encrypted with the third cipher. All these operations are performed +in CBC mode. + +The key for the first cipher is taken from the first 8 bytes of the +session key; the key for the next cipher from the next 8 bytes, and +the key for the third cipher from the following 8 bytes. All three +initialization vectors are initialized to zero. + +(Note: the variant of 3DES used here differs from some other +descriptions.) +.IP SSH_CIPHER_IDEA +The key is taken from the first 16 bytes of the session key. IDEA +[IDEA] is used in CFB mode. The initialization vector is initialized +to all zeroes. +.IP SSH_CIPHER_TSS +All 32 bytes of the session key are used as the key. + +There is no reference available for the TSS algorithm; it is currently +only documented in the sample implementation source code. The +security of this cipher is unknown (but it is quite fast). The cipher +is basically a stream cipher that uses MD5 as a random number +generator and takes feedback from the data. +.IP SSH_CIPHER_RC4 +The first 16 bytes of the session key are used as the key for the +server to client direction. The remaining 16 bytes are used as the +key for the client to server direction. This gives independent +128-bit keys for each direction. + +This algorithm is the alleged RC4 cipher posted to the Usenet in 1995. +It is widely believed to be equivalent with the original RSADSI RC4 +cipher. This is a very fast algorithm. +.RT + + +.ti 0 +Data Type Encodings + +The Data field of each packet contains data encoded as described in +this section. There may be several data items; each item is coded as +described here, and their representations are concatenated together +(without any alignment or padding). + +Each data type is stored as follows: +.IP "8-bit byte" +The byte is stored directly as a single byte. +.IP "32-bit unsigned integer" +Stored in 4 bytes, msb first. +.IP "Arbitrary length binary string" +First 4 bytes are the length of the string, msb first (not including +the length itself). The following "length" bytes are the string +value. There are no terminating null characters. +.IP "Multiple-precision integer" +First 2 bytes are the number of bits in the integer, msb first (for +example, the value 0x00012345 would have 17 bits). The value zero has +zero bits. It is permissible that the number of bits be larger than the +real number of bits. + +The number of bits is followed by (bits + 7) / 8 bytes of binary data, +msb first, giving the value of the integer. +.RT + + +.ti 0 +TCP/IP Port Number and Other Options + +The server listens for connections on TCP/IP port 22. + +The client may connect the server from any port. However, if the +client wishes to use any form of .rhosts or /etc/hosts.equiv +authentication, it must connect from a privileged port (less than +1024). + +For the IP Type of Service field [RFC0791], it is recommended that +interactive sessions (those having a user terminal or forwarding X11 +connections) use the IPTOS_LOWDELAY, and non-interactive connections +use IPTOS_THROUGHPUT. + +It is recommended that keepalives are used, because otherwise programs +on the server may never notice if the other end of the connection is +rebooted. + + +.ti 0 +Protocol Version Identification + +After the socket is opened, the server sends an identification string, +which is of the form +"SSH-.-\\n", where + and are integers and specify the +protocol version number (not software distribution version). + is server side software version string (max 40 characters); +it is not interpreted by the remote side but may be useful for +debugging. + +The client parses the server's string, and sends a corresponding +string with its own information in response. If the server has lower +version number, and the client contains special code to emulate it, +the client responds with the lower number; otherwise it responds with +its own number. The server then compares the version number the +client sent with its own, and determines whether they can work +together. The server either disconnects, or sends the first packet +using the binary packet protocol and both sides start working +according to the lower of the protocol versions. + +By convention, changes which keep the protocol compatible with +previous versions keep the same major protocol version; changes that +are not compatible increment the major version (which will hopefully +never happen). The version described in this document is 1.3. + +The client will + +.ti 0 +Key Exchange and Server Host Authentication + +The first message sent by the server using the packet protocol is +SSH_SMSG_PUBLIC_KEY. It declares the server's host key, server public +key, supported ciphers, supported authentication methods, and flags +for protocol extensions. It also contains a 64-bit random number +(cookie) that must be returned in the client's reply (to make IP +spoofing more difficult). No encryption is used for this message. + +Both sides compute a session id as follows. The modulus of the server +key is interpreted as a byte string (without explicit length field, +with minimum length able to hold the whole value), most significant +byte first. This string is concatenated with the server host key +interpreted the same way. Additionally, the cookie is concatenated +with this. Both sides compute MD5 of the resulting string. The +resulting 16 bytes (128 bits) are stored by both parties and are +called the session id. + +The client responds with a SSH_CMSG_SESSION_KEY message, which +contains the selected cipher type, a copy of the 64-bit cookie sent by +the server, client's protocol flags, and a session key encrypted +with both the server's host key and server key. No encryption is used +for this message. + +The session key is 32 8-bit bytes (a total of 256 random bits +generated by the client). The client first xors the 16 bytes of the +session id with the first 16 bytes of the session key. The resulting +string is then encrypted using the smaller key (one with smaller +modulus), and the result is then encrypted using the other key. The +number of bits in the public modulus of the two keys must differ by at +least 128 bits. + +At each encryption step, a multiple-precision integer is constructed +from the data to be encrypted as follows (the integer is here +interpreted as a sequence of bytes, msb first; the number of bytes is +the number of bytes needed to represent the modulus). + +The most significant byte (which is only partial as the value must be +less than the public modulus, which is never a power of two) is zero. + +The next byte contains the value 2 (which stands for public-key +encrypted data in the PKCS standard [PKCS#1]). Then, there are +non-zero random bytes to fill any unused space, a zero byte, and the +data to be encrypted in the least significant bytes, the last byte of +the data in the least significant byte. + +This algorithm is used twice. First, it is used to encrypt the 32 +random bytes generated by the client to be used as the session key +(xored by the session id). This value is converted to an integer as +described above, and encrypted with RSA using the key with the smaller +modulus. The resulting integer is converted to a byte stream, msb +first. This byte stream is padded and encrypted identically using the +key with the larger modulus. + +After the client has sent the session key, it starts to use the +selected algorithm and key for decrypting any received packets, and +for encrypting any sent packets. Separate ciphers are used for +different directions (that is, both directions have separate +initialization vectors or other state for the ciphers). + +When the server has received the session key message, and has turned +on encryption, it sends a SSH_SMSG_SUCCESS message to the client. + +The recommended size of the host key is 1024 bits, and 768 bits for +the server key. The minimum size is 512 bits for the smaller key. + + +.ti 0 +Declaring the User Name + +The client then sends a SSH_CMSG_USER message to the server. This +message specifies the user name to log in as. + +The server validates that such a user exists, checks whether +authentication is needed, and responds with either SSH_SMSG_SUCCESS or +SSH_SMSG_FAILURE. SSH_SMSG_SUCCESS indicates that no authentication +is needed for this user (no password), and authentication phase has +now been completed. SSH_SMSG_FAILURE indicates that authentication is +needed (or the user does not exist). + +If the user does not exist, it is recommended that this returns +failure, but the server keeps reading messages from the client, and +responds to any messages (except SSH_MSG_DISCONNECT, SSH_MSG_IGNORE, +and SSH_MSG_DEBUG) with SSH_SMSG_FAILURE. This way the client cannot +be certain whether the user exists. + + +.ti 0 +Authentication Phase + +Provided the server didn't immediately accept the login, an +authentication exchange begins. The client sends messages to the +server requesting different types of authentication in arbitrary order as +many times as desired (however, the server may close the connection +after a timeout). The server always responds with SSH_SMSG_SUCCESS if +it has accepted the authentication, and with SSH_SMSG_FAILURE if it has +denied authentication with the requested method or it does not +recognize the message. Some authentication methods cause an exchange +of further messages before the final result is sent. The +authentication phase ends when the server responds with success. + +The recommended value for the authentication timeout (timeout before +disconnecting if no successful authentication has been made) is 5 +minutes. + +The following authentication methods are currently supported: +.TS +center; +l r l. +SSH_AUTH_RHOSTS 1 .rhosts or /etc/hosts.equiv +SSH_AUTH_RSA 2 pure RSA authentication +SSH_AUTH_PASSWORD 3 password authentication +SSH_AUTH_RHOSTS_RSA 4 .rhosts with RSA host authentication +.TE +.IP SSH_AUTH_RHOSTS + +This is the authentication method used by rlogin and rsh [RFC1282]. + +The client sends SSH_CMSG_AUTH_RHOSTS with the client-side user name +as an argument. + +The server checks whether to permit authentication. On UNIX systems, +this is usually done by checking /etc/hosts.equiv, and .rhosts in the +user's home directory. The connection must come from a privileged +port. + +It is recommended that the server checks that there are no IP options +(such as source routing) specified for the socket before accepting +this type of authentication. The client host name should be +reverse-mapped and then forward mapped to ensure that it has the +proper IP-address. + +This authentication method trusts the remote host (root on the remote +host can pretend to be any other user on that host), the name +services, and partially the network: anyone who can see packets coming +out from the server machine can do IP-spoofing and pretend to be any +machine; however, the protocol prevents blind IP-spoofing (which used +to be possible with rlogin). + +Many sites probably want to disable this authentication method because +of the fundamental insecurity of conventional .rhosts or +/etc/hosts.equiv authentication when faced with spoofing. It is +recommended that this method not be supported by the server by +default. +.IP SSH_AUTH_RHOSTS_RSA + +In addition to conventional .rhosts and hosts.equiv authentication, +this method additionally requires that the client host be +authenticated using RSA. + +The client sends SSH_CMSG_AUTH_RHOSTS_RSA specifying the client-side +user name, and the public host key of the client host. + +The server first checks if normal .rhosts or /etc/hosts.equiv +authentication would be accepted, and if not, responds with +SSH_SMSG_FAILURE. Otherwise, it checks whether it knows the host key +for the client machine (using the same name for the host that was used +for checking the .rhosts and /etc/hosts.equiv files). If it does not +know the RSA key for the client, access is denied and SSH_SMSG_FAILURE +is sent. + +If the server knows the host key of the client machine, it verifies +that the given host key matches that known for the client. If not, +access is denied and SSH_SMSG_FAILURE is sent. + +The server then sends a SSH_SMSG_AUTH_RSA_CHALLENGE message containing +an encrypted challenge for the client. The challenge is 32 8-bit +random bytes (256 bits). When encrypted, the highest (partial) byte +is left as zero, the next byte contains the value 2, the following are +non-zero random bytes, followed by a zero byte, and the challenge put +in the remaining bytes. This is then encrypted using RSA with the +client host's public key. (The padding and encryption algorithm is +the same as that used for the session key.) + +The client decrypts the challenge using its private host key, +concatenates this with the session id, and computes an MD5 checksum +of the resulting 48 bytes. The MD5 output is returned as 16 bytes in +a SSH_CMSG_AUTH_RSA_RESPONSE message. (MD5 is used to deter chosen +plaintext attacks against RSA; the session id binds it to a specific +session). + +The server verifies that the MD5 of the decrypted challenge returned by +the client matches that of the original value, and sends SSH_SMSG_SUCCESS if +so. Otherwise it sends SSH_SMSG_FAILURE and refuses the +authentication attempt. + +This authentication method trusts the client side machine in that root +on that machine can pretend to be any user on that machine. +Additionally, it trusts the client host key. The name and/or IP +address of the client host is only used to select the public host key. +The same host name is used when scanning .rhosts or /etc/hosts.equiv +and when selecting the host key. It would in principle be possible to +eliminate the host name entirely and substitute it directly by the +host key. IP and/or DNS [RFC1034] spoofing can only be used +to pretend to be a host for which the attacker has the private host +key. +.IP SSH_AUTH_RSA + +The idea behind RSA authentication is that the server recognizes the +public key offered by the client, generates a random challenge, and +encrypts the challenge with the public key. The client must then +prove that it has the corresponding private key by decrypting the +challenge. + +The client sends SSH_CMSG_AUTH_RSA with public key modulus (n) as an +argument. + +The server may respond immediately with SSH_SMSG_FAILURE if it does +not permit authentication with this key. Otherwise it generates a +challenge, encrypts it using the user's public key (stored on the +server and identified using the modulus), and sends +SSH_SMSG_AUTH_RSA_CHALLENGE with the challenge (mp-int) as an +argument. + +The challenge is 32 8-bit random bytes (256 bits). When encrypted, +the highest (partial) byte is left as zero, the next byte contains the +value 2, the following are non-zero random bytes, followed by a zero +byte, and the challenge put in the remaining bytes. This is then +encrypted with the public key. (The padding and encryption algorithm +is the same as that used for the session key.) + +The client decrypts the challenge using its private key, concatenates +it with the session id, and computes an MD5 checksum of the resulting +48 bytes. The MD5 output is returned as 16 bytes in a +SSH_CMSG_AUTH_RSA_RESPONSE message. (Note that the MD5 is necessary +to avoid chosen plaintext attacks against RSA; the session id binds it +to a specific session.) + +The server verifies that the MD5 of the decrypted challenge returned +by the client matches that of the original value, and sends +SSH_SMSG_SUCCESS if so. Otherwise it sends SSH_SMSG_FAILURE and +refuses the authentication attempt. + +This authentication method does not trust the remote host, the +network, name services, or anything else. Authentication is based +solely on the possession of the private identification keys. Anyone +in possession of the private keys can log in, but nobody else. + +The server may have additional requirements for a successful +authentiation. For example, to limit damage due to a compromised RSA +key, a server might restrict access to a limited set of hosts. +.IP SSH_AUTH_PASSWORD + +The client sends a SSH_CMSG_AUTH_PASSWORD message with the plain text +password. (Note that even though the password is plain text inside +the message, it is normally encrypted by the packet mechanism.) + +The server verifies the password, and sends SSH_SMSG_SUCCESS if +authentication was accepted and SSH_SMSG_FAILURE otherwise. + +Note that the password is read from the user by the client; the user +never interacts with a login program. + +This authentication method does not trust the remote host, the +network, name services or anything else. Authentication is based +solely on the possession of the password. Anyone in possession of the +password can log in, but nobody else. +.RT + +.ti 0 +Preparatory Operations + +After successful authentication, the server waits for a request from +the client, processes the request, and responds with SSH_SMSG_SUCCESS +whenever a request has been successfully processed. If it receives a +message that it does not recognize or it fails to honor a request, it +returns SSH_SMSG_FAILURE. It is expected that new message types might +be added to this phase in future. + +The following messages are currently defined for this phase. +.IP SSH_CMSG_REQUEST_COMPRESSION +Requests that compression be enabled for this session. A +gzip-compatible compression level (1-9) is passed as an argument. +.IP SSH_CMSG_REQUEST_PTY +Requests that a pseudo terminal device be allocated for this session. +The user terminal type and terminal modes are supplied as arguments. +.IP SSH_CMSG_X11_REQUEST_FORWARDING +Requests forwarding of X11 connections from the remote machine to the +local machine over the secure channel. Causes an internet-domain +socket to be allocated and the DISPLAY variable to be set on the server. +X11 authentication data is automatically passed to the server, and the +client may implement spoofing of authentication data for added +security. The authentication data is passed as arguments. +.IP SSH_CMSG_PORT_FORWARD_REQUEST +Requests forwarding of a TCP/IP port on the server host over the +secure channel. What happens is that whenever a connection is made to +the port on the server, a connection will be made from the client end +to the specified host/port. Any user can forward unprivileged ports; +only the root can forward privileged ports (as determined by +authentication done earlier). +.IP SSH_CMSG_AGENT_REQUEST_FORWARDING +Requests forwarding of the connection to the authentication agent. +.IP SSH_CMSG_EXEC_SHELL +Starts a shell (command interpreter) for the user, and moves into +interactive session mode. +.IP SSH_CMSG_EXEC_CMD +Executes the given command (actually " -c " or +equivalent) for the user, and moves into interactive session mode. +.RT + + +.ti 0 +Interactive Session and Exchange of Data + +During the interactive session, any data written by the shell or +command running on the server machine is forwarded to stdin or +stderr on the client machine, and any input available from stdin on +the client machine is forwarded to the program on the server machine. + +All exchange is asynchronous; either side can send at any time, and +there are no acknowledgements (TCP/IP already provides reliable +transport, and the packet protocol protects against tampering or IP +spoofing). + +When the client receives EOF from its standard input, it will send +SSH_CMSG_EOF; however, this in no way terminates the exchange. The +exchange terminates and interactive mode is left when the server sends +SSH_SMSG_EXITSTATUS to indicate that the client program has +terminated. Alternatively, either side may disconnect at any time by +sending SSH_MSG_DISCONNECT or closing the connection. + +The server may send any of the following messages: +.IP SSH_SMSG_STDOUT_DATA +Data written to stdout by the program running on the server. The data +is passed as a string argument. The client writes this data to +stdout. +.IP SSH_SMSG_STDERR_DATA +Data written to stderr by the program running on the server. The data +is passed as a string argument. The client writes this data to +stderr. (Note that if the program is running on a tty, it is not +possible to separate stdout and stderr data, and all data will be sent +as stdout data.) +.IP SSH_SMSG_EXITSTATUS +Indicates that the shell or command has exited. Exit status is passed +as an integer argument. This message causes termination of the +interactive session. +.IP SSH_SMSG_AGENT_OPEN +Indicates that someone on the server side is requesting a connection +to the authentication agent. The server-side channel number is passed +as an argument. The client must respond with either +SSH_CHANNEL_OPEN_CONFIRMATION or SSH_CHANNEL_OPEN_FAILURE. +.IP SSH_SMSG_X11_OPEN +Indicates that a connection has been made to the X11 socket on the +server side and should be forwarded to the real X server. An integer +argument indicates the channel number allocated for this connection on +the server side. The client should send back either +SSH_MSG_CHANNEL_OPEN_CONFIRMATION or SSH_MSG_CHANNEL_OPEN_FAILURE with +the same server side channel number. +.IP SSH_MSG_PORT_OPEN +Indicates that a connection has been made to a port on the server side +for which forwarding has been requested. Arguments are server side +channel number, host name to connect to, and port to connect to. The +client should send back either +SSH_MSG_CHANNEL_OPEN_CONFIRMATION or SSH_MSG_CHANNEL_OPEN_FAILURE with +the same server side channel number. +.IP SSH_MSG_CHANNEL_OPEN_CONFIRMATION +This is sent by the server to indicate that it has opened a connection +as requested in a previous message. The first argument indicates the +client side channel number, and the second argument is the channel number +that the server has allocated for this connection. +.IP SSH_MSG_CHANNEL_OPEN_FAILURE +This is sent by the server to indicate that it failed to open a +connection as requested in a previous message. The client-side +channel number is passed as an argument. The client will close the +descriptor associated with the channel and free the channel. +.IP SSH_MSG_CHANNEL_DATA +This packet contains data for a channel from the server. The first +argument is the client-side channel number, and the second argument (a +string) is the data. +.IP SSH_MSG_CHANNEL_CLOSE +This is sent by the server to indicate that whoever was in the other +end of the channel has closed it. The argument is the client side channel +number. The client will let all buffered data in the channel to +drain, and when ready, will close the socket, free the channel, and +send the server a SSH_MSG_CHANNEL_CLOSE_CONFIRMATION message for the +channel. +.IP SSH_MSG_CHANNEL_CLOSE_CONFIRMATION +This is send by the server to indicate that a channel previously +closed by the client has now been closed on the server side as well. +The argument indicates the client channel number. The client frees +the channel. +.RT + +The client may send any of the following messages: +.IP SSH_CMSG_STDIN_DATA +This is data to be sent as input to the program running on the server. +The data is passed as a string. +.IP SSH_CMSG_EOF +Indicates that the client has encountered EOF while reading standard +input. The server will allow any buffered input data to drain, and +will then close the input to the program. +.IP SSH_CMSG_WINDOW_SIZE +Indicates that window size on the client has been changed. The server +updates the window size of the tty and causes SIGWINCH to be sent to +the program. The new window size is passed as four integer arguments: +row, col, xpixel, ypixel. +.IP SSH_MSG_PORT_OPEN +Indicates that a connection has been made to a port on the client side +for which forwarding has been requested. Arguments are client side +channel number, host name to connect to, and port to connect to. The +server should send back either SSH_MSG_CHANNEL_OPEN_CONFIRMATION or +SSH_MSG_CHANNEL_OPEN_FAILURE with the same client side channel number. +.IP SSH_MSG_CHANNEL_OPEN_CONFIRMATION +This is sent by the client to indicate that it has opened a connection +as requested in a previous message. The first argument indicates the +server side channel number, and the second argument is the channel +number that the client has allocated for this connection. +.IP SSH_MSG_CHANNEL_OPEN_FAILURE +This is sent by the client to indicate that it failed to open a +connection as requested in a previous message. The server side +channel number is passed as an argument. The server will close the +descriptor associated with the channel and free the channel. +.IP SSH_MSG_CHANNEL_DATA +This packet contains data for a channel from the client. The first +argument is the server side channel number, and the second argument (a +string) is the data. +.IP SSH_MSG_CHANNEL_CLOSE +This is sent by the client to indicate that whoever was in the other +end of the channel has closed it. The argument is the server channel +number. The server will allow buffered data to drain, and when ready, +will close the socket, free the channel, and send the client a +SSH_MSG_CHANNEL_CLOSE_CONFIRMATION message for the channel. +.IP SSH_MSG_CHANNEL_CLOSE_CONFIRMATION +This is send by the client to indicate that a channel previously +closed by the server has now been closed on the client side as well. +The argument indicates the server channel number. The server frees +the channel. +.RT + +Any unsupported messages during interactive mode cause the connection +to be terminated with SSH_MSG_DISCONNECT and an error message. +Compatible protocol upgrades should agree about any extensions during +the preparation phase or earlier. + + +.ti 0 +Termination of the Connection + +Normal termination of the connection is always initiated by the server +by sending SSH_SMSG_EXITSTATUS after the program has exited. The +client responds to this message by sending SSH_CMSG_EXIT_CONFIRMATION +and closes the socket; the server then closes the socket. There are +two purposes for the confirmation: some systems may lose previously +sent data when the socket is closed, and closing the client side first +causes any TCP/IP TIME_WAIT [RFC0793] waits to occur on the client side, not +consuming server resources. + +If the program terminates due to a signal, the server will send +SSH_MSG_DISCONNECT with an appropriate message. If the connection is +closed, all file descriptors to the program will be closed and the +server will exit. If the program runs on a tty, the kernel sends it +the SIGHUP signal when the pty master side is closed. + +.ti 0 +Protocol Flags + +Both the server and the client pass 32 bits of protocol flags to the +other side. The flags are intended for compatible protocol extension; +the server first announces which added capabilities it supports, and +the client then sends the capabilities that it supports. + +The following flags are currently defined (the values are bit masks): +.IP "1 SSH_PROTOFLAG_SCREEN_NUMBER" +This flag can only be sent by the client. It indicates that the X11 +forwarding requests it sends will include the screen number. +.IP "2 SSH_PROTOFLAG_HOST_IN_FWD_OPEN" +If both sides specify this flag, SSH_SMSG_X11_OPEN and +SSH_MSG_PORT_OPEN messages will contain an additional field containing +a description of the host at the other end of the connection. +.RT + +.ti 0 +Detailed Description of Packet Types and Formats + +The supported packet types and the corresponding message numbers are +given in the following table. Messages with _MSG_ in their name may +be sent by either side. Messages with _CMSG_ are only sent by the +client, and messages with _SMSG_ only by the server. + +A packet may contain additional data after the arguments specified +below. Any such data should be ignored by the receiver. However, it +is recommended that no such data be stored without good reason. (This +helps build compatible extensions.) +.IP "0 SSH_MSG_NONE" +This code is reserved. This message type is never sent. +.IP "1 SSH_MSG_DISCONNECT" +.TS +; +l l. +string Cause of disconnection +.TE +This message may be sent by either party at any time. It causes the +immediate disconnection of the connection. The message is intended to +be displayed to a human, and describes the reason for disconnection. +.IP "2 SSH_SMSG_PUBLIC_KEY" +.TS +; +l l. +8 bytes anti_spoofing_cookie +32-bit int server_key_bits +mp-int server_key_public_exponent +mp-int server_key_public_modulus +32-bit int host_key_bits +mp-int host_key_public_exponent +mp-int host_key_public_modulus +32-bit int protocol_flags +32-bit int supported_ciphers_mask +32-bit int supported_authentications_mask +.TE +Sent as the first message by the server. This message gives the +server's host key, server key, protocol flags (intended for compatible +protocol extension), supported_ciphers_mask (which is the +bitwise or of (1 << cipher_number), where << is the left shift +operator, for all supported ciphers), and +supported_authentications_mask (which is the bitwise or of (1 << +authentication_type) for all supported authentication types). The +anti_spoofing_cookie is 64 random bytes, and must be sent back +verbatim by the client in its reply. It is used to make IP-spoofing +more difficult (encryption and host keys are the real defense against +spoofing). +.IP "3 SSH_CMSG_SESSION_KEY" +.TS +; +l l. +1 byte cipher_type (must be one of the supported values) +8 bytes anti_spoofing_cookie (must match data sent by the server) +mp-int double-encrypted session key +32-bit int protocol_flags +.TE +Sent by the client as the first message in the session. Selects the +cipher to use, and sends the encrypted session key to the server. The +anti_spoofing_cookie must be the same bytes that were sent by the +server. Protocol_flags is intended for negotiating compatible +protocol extensions. +.IP "4 SSH_CMSG_USER" +.TS +; +l l. +string user login name on server +.TE +Sent by the client to begin authentication. Specifies the user name +on the server to log in as. The server responds with SSH_SMSG_SUCCESS +if no authentication is needed for this user, or SSH_SMSG_FAILURE if +authentication is needed (or the user does not exist). [Note to the +implementator: the user name is of arbitrary size. The implementation +must be careful not to overflow internal buffers.] +.IP "5 SSH_CMSG_AUTH_RHOSTS" +.TS +; +l l. +string client-side user name +.TE +Requests authentication using /etc/hosts.equiv and .rhosts (or +equivalent mechanisms). This authentication method is normally +disabled in the server because it is not secure (but this is the +method used by rsh and rlogin). The server responds with +SSH_SMSG_SUCCESS if authentication was successful, and +SSH_SMSG_FAILURE if access was not granted. The server should check +that the client side port number is less than 1024 (a privileged +port), and immediately reject authentication if it is not. Supporting +this authentication method is optional. This method should normally +not be enabled in the server because it is not safe. (However, not +enabling this only helps if rlogind and rshd are disabled.) +.IP "6 SSH_CMSG_AUTH_RSA" +.TS +; +l l. +mp-int identity_public_modulus +.TE +Requests authentication using pure RSA authentication. The server +checks if the given key is permitted to log in, and if so, responds +with SSH_SMSG_AUTH_RSA_CHALLENGE. Otherwise, it responds with +SSH_SMSG_FAILURE. The client often tries several different keys in +sequence until one supported by the server is found. Authentication +is accepted if the client gives the correct response to the challenge. +The server is free to add other criteria for authentication, such as a +requirement that the connection must come from a certain host. Such +additions are not visible at the protocol level. Supporting this +authentication method is optional but recommended. +.IP "7 SSH_SMSG_AUTH_RSA_CHALLENGE" +.TS +; +l l. +mp-int encrypted challenge +.TE +Presents an RSA authentication challenge to the client. The challenge +is a 256-bit random value encrypted as described elsewhere in this +document. The client must decrypt the challenge using the RSA private +key, compute MD5 of the challenge plus session id, and send back the +resulting 16 bytes using SSH_CMSG_AUTH_RSA_RESPONSE. +.IP "8 SSH_CMSG_AUTH_RSA_RESPONSE" +.TS +; +l l. +16 bytes MD5 of decrypted challenge +.TE +This message is sent by the client in response to an RSA challenge. +The MD5 checksum is returned instead of the decrypted challenge to +deter known-plaintext attacks against the RSA key. The server +responds to this message with either SSH_SMSG_SUCCESS or +SSH_SMSG_FAILURE. +.IP "9 SSH_CMSG_AUTH_PASSWORD" +.TS +; +l l. +string plain text password +.TE +Requests password authentication using the given password. Note that +even though the password is plain text inside the packet, the whole +packet is normally encrypted by the packet layer. It would not be +possible for the client to perform password encryption/hashing, +because it cannot know which kind of encryption/hashing, if any, the +server uses. The server responds to this message with +SSH_SMSG_SUCCESS or SSH_SMSG_FAILURE. +.IP "10 SSH_CMSG_REQUEST_PTY" +.TS +; +l l. +string TERM environment variable value (e.g. vt100) +32-bit int terminal height, rows (e.g., 24) +32-bit int terminal width, columns (e.g., 80) +32-bit int terminal width, pixels (0 if no graphics) (e.g., 480) +32-bit int terminal height, pixels (0 if no graphics) (e.g., 640) +n bytes tty modes encoded in binary +.TE +Requests a pseudo-terminal to be allocated for this command. This +message can be used regardless of whether the session will later +execute the shell or a command. If a pty has been requested with this +message, the shell or command will run on a pty. Otherwise it will +communicate with the server using pipes, sockets or some other similar +mechanism. + +The terminal type gives the type of the user's terminal. In the UNIX +environment it is passed to the shell or command in the TERM +environment variable. + +The width and height values give the initial size of the user's +terminal or window. All values can be zero if not supported by the +operating system. The server will pass these values to the kernel if +supported. + +Terminal modes are encoded into a byte stream in a portable format. +The exact format is described later in this document. + +The server responds to the request with either SSH_SMSG_SUCCESS or +SSH_SMSG_FAILURE. If the server does not have the concept of pseudo +terminals, it should return success if it is possible to execute a +shell or a command so that it looks to the client as if it was running +on a pseudo terminal. +.IP "11 SSH_CMSG_WINDOW_SIZE" +.TS +; +l l. +32-bit int terminal height, rows +32-bit int terminal width, columns +32-bit int terminal width, pixels +32-bit int terminal height, pixels +.TE +This message can only be sent by the client during the interactive +session. This indicates that the size of the user's window has +changed, and provides the new size. The server will update the +kernel's notion of the window size, and a SIGWINCH signal or +equivalent will be sent to the shell or command (if supported by the +operating system). +.IP "12 SSH_CMSG_EXEC_SHELL" + +(no arguments) + +Starts a shell (command interpreter), and enters interactive session +mode. +.IP "13 SSH_CMSG_EXEC_CMD" +.TS +; +l l. +string command to execute +.TE +Starts executing the given command, and enters interactive session +mode. On UNIX, the command is run as " -c ", where + is the user's login shell. +.IP "14 SSH_SMSG_SUCCESS" + +(no arguments) + +This message is sent by the server in response to the session key, a +successful authentication request, and a successfully completed +preparatory operation. +.IP "15 SSH_SMSG_FAILURE" + +(no arguments) + +This message is sent by the server in response to a failed +authentication operation to indicate that the user has not yet been +successfully authenticated, and in response to a failed preparatory +operation. This is also sent in response to an authentication or +preparatory operation request that is not recognized or supported. +.IP "16 SSH_CMSG_STDIN_DATA" +.TS +; +l l. +string data +.TE +Delivers data from the client to be supplied as input to the shell or +program running on the server side. This message can only be used in +the interactive session mode. No acknowledgement is sent for this +message. +.IP "17 SSH_SMSG_STDOUT_DATA" +.TS +; +l l. +string data +.TE +Delivers data from the server that was read from the standard output of +the shell or program running on the server side. This message can +only be used in the interactive session mode. No acknowledgement is +sent for this message. +.IP "18 SSH_SMSG_STDERR_DATA" +.TS +; +l l. +string data +.TE +Delivers data from the server that was read from the standard error of +the shell or program running on the server side. This message can +only be used in the interactive session mode. No acknowledgement is +sent for this message. +.IP "19 SSH_CMSG_EOF" + +(no arguments) + +This message is sent by the client to indicate that EOF has been +reached on the input. Upon receiving this message, and after all +buffered input data has been sent to the shell or program, the server +will close the input file descriptor to the program. This message can +only be used in the interactive session mode. No acknowledgement is +sent for this message. +.IP "20 SSH_SMSG_EXITSTATUS" +.TS +; +l l. +32-bit int exit status of the command +.TE +Returns the exit status of the shell or program after it has exited. +The client should respond with SSH_CMSG_EXIT_CONFIRMATION when it has +received this message. This will be the last message sent by the +server. If the program being executed dies with a signal instead of +exiting normally, the server should terminate the session with +SSH_MSG_DISCONNECT (which can be used to pass a human-readable string +indicating that the program died due to a signal) instead of using +this message. +.IP "21 SSH_MSG_CHANNEL_OPEN_CONFIRMATION" +.TS +; +l l. +32-bit int remote_channel +32-bit int local_channel +.TE +This is sent in response to any channel open request if the channel +has been successfully opened. Remote_channel is the channel number +received in the initial open request; local_channel is the channel +number the side sending this message has allocated for the channel. +Data can be transmitted on the channel after this message. +.IP "22 SSH_MSG_CHANNEL_OPEN_FAILURE" +.TS +; +l l. +32-bit int remote_channel +.TE +This message indicates that an earlier channel open request by the +other side has failed or has been denied. Remote_channel is the +channel number given in the original request. +.IP "23 SSH_MSG_CHANNEL_DATA" +.TS +; +l l. +32-bit int remote_channel +string data +.TE +Data is transmitted in a channel in these messages. A channel is +bidirectional, and both sides can send these messages. There is no +acknowledgement for these messages. It is possible that either side +receives these messages after it has sent SSH_MSG_CHANNEL_CLOSE for +the channel. These messages cannot be received after the party has +sent or received SSH_MSG_CHANNEL_CLOSE_CONFIRMATION. +.IP "24 SSH_MSG_CHANNEL_CLOSE" +.TS +; +l l. +32-bit int remote_channel +.TE +When a channel is closed at one end of the connection, that side sends +this message. Upon receiving this message, the channel should be +closed. When this message is received, if the channel is already +closed (the receiving side has sent this message for the same channel +earlier), the channel is freed and no further action is taken; +otherwise the channel is freed and SSH_MSG_CHANNEL_CLOSE_CONFIRMATION +is sent in response. (It is possible that the channel is closed +simultaneously at both ends.) +.IP "25 SSH_MSG_CHANNEL_CLOSE_CONFIRMATION" +.TS +; +l l. +32-bit int remote_channel +.TE +This message is sent in response to SSH_MSG_CHANNEL_CLOSE unless the +channel was already closed. When this message is sent or received, +the channel is freed. +.IP "26 (OBSOLETED; was unix-domain X11 forwarding) +.IP "27 SSH_SMSG_X11_OPEN" +.TS +; +l l. +32-bit int local_channel +string originator_string (see below) +.TE +This message can be sent by the server during the interactive session +mode to indicate that a client has connected the fake X server. +Local_channel is the channel number that the server has allocated for +the connection. The client should try to open a connection to the +real X server, and respond with SSH_MSG_CHANNEL_OPEN_CONFIRMATION or +SSH_MSG_CHANNEL_OPEN_FAILURE. + +The field originator_string is present if both sides +specified SSH_PROTOFLAG_HOST_IN_FWD_OPEN in the protocol flags. It +contains a description of the host originating the connection. +.IP "28 SSH_CMSG_PORT_FORWARD_REQUEST" +.TS +; +l l. +32-bit int server_port +string host_to_connect +32-bit int port_to_connect +.TE +Sent by the client in the preparatory phase, this message requests +that server_port on the server machine be forwarded over the secure +channel to the client machine, and from there to the specified host +and port. The server should start listening on the port, and send +SSH_MSG_PORT_OPEN whenever a connection is made to it. Supporting +this message is optional, and the server is free to reject any forward +request. For example, it is highly recommended that unless the user +has been authenticated as root, forwarding any privileged port numbers +(below 1024) is denied. +.IP "29 SSH_MSG_PORT_OPEN" +.TS +; +l l. +32-bit int local_channel +string host_name +32-bit int port +string originator_string (see below) +.TE +Sent by either party in interactive session mode, this message +indicates that a connection has been opened to a forwarded TCP/IP +port. Local_channel is the channel number that the sending party has +allocated for the connection. Host_name is the host the connection +should be be forwarded to, and the port is the port on that host to +connect. The receiving party should open the connection, and respond +with SSH_MSG_CHANNEL_OPEN_CONFIRMATION or +SSH_MSG_CHANNEL_OPEN_FAILURE. It is recommended that the receiving +side check the host_name and port for validity to avoid compromising +local security by compromised remote side software. Particularly, it +is recommended that the client permit connections only to those ports +for which it has requested forwarding with SSH_CMSG_PORT_FORWARD_REQUEST. + +The field originator_string is present if both sides +specified SSH_PROTOFLAG_HOST_IN_FWD_OPEN in the protocol flags. It +contains a description of the host originating the connection. +.IP "30 SSH_CMSG_AGENT_REQUEST_FORWARDING" + +(no arguments) + +Requests that the connection to the authentication agent be forwarded +over the secure channel. The method used by clients to contact the +authentication agent within each machine is implementation and machine +dependent. If the server accepts this request, it should arrange that +any clients run from this session will actually contact the server +program when they try to contact the authentication agent. The server +should then send a SSH_SMSG_AGENT_OPEN to open a channel to the agent, +and the client should forward the connection to the real +authentication agent. Supporting this message is optional. +.IP "31 SSH_SMSG_AGENT_OPEN" +.TS +; +l l. +32-bit int local_channel +.TE +Sent by the server in interactive session mode, this message requests +opening a channel to the authentication agent. The client should open +a channel, and respond with either SSH_MSG_CHANNEL_OPEN_CONFIRMATION +or SSH_MSG_CHANNEL_OPEN_FAILURE. +.IP "32 SSH_MSG_IGNORE" +.TS +; +l l. +string data +.TE +Either party may send this message at any time. This message, and the +argument string, is silently ignored. This message might be used in +some implementations to make traffic analysis more difficult. This +message is not currently sent by the implementation, but all +implementations are required to recognize and ignore it. +.IP "33 SSH_CMSG_EXIT_CONFIRMATION" + +(no arguments) + +Sent by the client in response to SSH_SMSG_EXITSTATUS. This is the +last message sent by the client. +.IP "34 SSH_CMSG_X11_REQUEST_FORWARDING" +.TS +; +l l. +string x11_authentication_protocol +string x11_authentication_data +32-bit int screen number (if SSH_PROTOFLAG_SCREEN_NUMBER) +.TE +Sent by the client during the preparatory phase, this message requests +that the server create a fake X11 display and set the DISPLAY +environment variable accordingly. An internet-domain display is +preferable. The given authentication protocol and the associated data +should be recorded by the server so that it is used as authentication +on connections (e.g., in .Xauthority). The authentication protocol +must be one of the supported X11 authentication protocols, e.g., +"MIT-MAGIC-COOKIE-1". Authentication data must be a lowercase hex +string of even length. Its interpretation is protocol dependent. +The data is in a format that can be used with e.g. the xauth program. +Supporting this message is optional. + +The client is permitted (and recommended) to generate fake +authentication information and send fake information to the server. +This way, a corrupt server will not have access to the user's terminal +after the connection has terminated. The correct authorization codes +will also not be left hanging around in files on the server (many +users keep the same X session for months, thus protecting the +authorization data becomes important). + +X11 authentication spoofing works by initially sending fake (random) +authentication data to the server, and interpreting the first packet +sent by the X11 client after the connection has been opened. The +first packet contains the client's authentication. If the packet +contains the correct fake data, it is replaced by the client by the +correct authentication data, and then sent to the X server. +.IP "35 SSH_CMSG_AUTH_RHOSTS_RSA" +.TS +; +l l. +string clint-side user name +32-bit int client_host_key_bits +mp-int client_host_key_public_exponent +mp-int client_host_key_public_modulus +.TE +Requests authentication using /etc/hosts.equiv and .rhosts (or +equivalent) together with RSA host authentication. The server should +check that the client side port number is less than 1024 (a privileged +port), and immediately reject authentication if it is not. The server +responds with SSH_SMSG_FAILURE or SSH_SMSG_AUTH_RSA_CHALLENGE. The +client must respond to the challenge with the proper +SSH_CMSG_AUTH_RSA_RESPONSE. The server then responds with success if +access was granted, or failure if the client gave a wrong response. +Supporting this authentication method is optional but recommended in +most environments. +.IP "36 SSH_MSG_DEBUG" +.TS +; +l l. +string debugging message sent to the other side +.TE +This message may be sent by either party at any time. It is used to +send debugging messages that may be informative to the user in +solving various problems. For example, if authentication fails +because of some configuration error (e.g., incorrect permissions for +some file), it can be very helpful for the user to make the cause of +failure available. On the other hand, one should not make too much +information available for security reasons. It is recommended that +the client provides an option to display the debugging information +sent by the sender (the user probably does not want to see it by default). +The server can log debugging data sent by the client (if any). Either +party is free to ignore any received debugging data. Every +implementation must be able to receive this message, but no +implementation is required to send these. +.IP "37 SSH_CMSG_REQUEST_COMPRESSION" +.TS +; +l l. +32-bit int gzip compression level (1-9) +.TE +This message can be sent by the client in the preparatory operations +phase. The server responds with SSH_SMSG_FAILURE if it does not +support compression or does not want to compress; it responds with +SSH_SMSG_SUCCESS if it accepted the compression request. In the +latter case the response to this packet will still be uncompressed, +but all further packets in either direction will be compressed by gzip. +.RT + + +.ti 0 +Encoding of Terminal Modes + +Terminal modes (as passed in SSH_CMSG_REQUEST_PTY) are encoded into a +byte stream. It is intended that the coding be portable across +different environments. + +The tty mode description is a stream of bytes. The stream consists of +opcode-argument pairs. It is terminated by opcode TTY_OP_END (0). +Opcodes 1-127 have one-byte arguments. Opcodes 128-159 have 32-bit +integer arguments (stored msb first). Opcodes 160-255 are not yet +defined, and cause parsing to stop (they should only be used after any +other data). + +The client puts in the stream any modes it knows about, and the server +ignores any modes it does not know about. This allows some degree of +machine-independence, at least between systems that use a POSIX-like +[POSIX] tty interface. The protocol can support other systems as +well, but the client may need to fill reasonable values for a number +of parameters so the server pty gets set to a reasonable mode (the +server leaves all unspecified mode bits in their default values, and +only some combinations make sense). + +The following opcodes have been defined. The naming of opcodes mostly +follows the POSIX terminal mode flags. +.IP "0 TTY_OP_END" +Indicates end of options. +.IP "1 VINTR" +Interrupt character; 255 if none. Similarly for the other characters. +Not all of these characters are supported on all systems. +.IP "2 VQUIT" +The quit character (sends SIGQUIT signal on UNIX systems). +.IP "3 VERASE" +Erase the character to left of the cursor. +.IP "4 VKILL" +Kill the current input line. +.IP "5 VEOF " +End-of-file character (sends EOF from the terminal). +.IP "6 VEOL " +End-of-line character in addition to carriage return and/or linefeed. +.IP "7 VEOL2" +Additional end-of-line character. +.IP "8 VSTART" +Continues paused output (normally ^Q). +.IP "9 VSTOP" +Pauses output (^S). +.IP "10 VSUSP" +Suspends the current program. +.IP "11 VDSUSP" +Another suspend character. +.IP "12 VREPRINT" +Reprints the current input line. +.IP "13 VWERASE" +Erases a word left of cursor. +.IP "14 VLNEXT" +More special input characters; these are probably not supported on +most systems. +.IP "15 VFLUSH" +.IP "16 VSWTCH" +.IP "17 VSTATUS" +.IP "18 VDISCARD" + +.IP "30 IGNPAR" +The ignore parity flag. The next byte should be 0 if this flag is not +set, and 1 if it is set. +.IP "31 PARMRK" +More flags. The exact definitions can be found in the POSIX standard. +.IP "32 INPCK" +.IP "33 ISTRIP" +.IP "34 INLCR" +.IP "35 IGNCR" +.IP "36 ICRNL" +.IP "37 IUCLC" +.IP "38 IXON" +.IP "39 IXANY" +.IP "40 IXOFF" +.IP "41 IMAXBEL" + +.IP "50 ISIG" +.IP "51 ICANON" +.IP "52 XCASE" +.IP "53 ECHO" +.IP "54 ECHOE" +.IP "55 ECHOK" +.IP "56 ECHONL" +.IP "57 NOFLSH" +.IP "58 TOSTOP" +.IP "59 IEXTEN" +.IP "60 ECHOCTL" +.IP "61 ECHOKE" +.IP "62 PENDIN" + +.IP "70 OPOST" +.IP "71 OLCUC" +.IP "72 ONLCR" +.IP "73 OCRNL" +.IP "74 ONOCR" +.IP "75 ONLRET" + +.IP "90 CS7" +.IP "91 CS8" +.IP "92 PARENB" +.IP "93 PARODD" + +.IP "192 TTY_OP_ISPEED" +Specifies the input baud rate in bits per second. +.IP "193 TTY_OP_OSPEED" +Specifies the output baud rate in bits per second. +.RT + + +.ti 0 +The Authentication Agent Protocol + +The authentication agent is a program that can be used to hold RSA +authentication keys for the user (in future, it might hold data for +other authentication types as well). An authorized program can send +requests to the agent to generate a proper response to an RSA +challenge. How the connection is made to the agent (or its +representative) inside a host and how access control is done inside a +host is implementation-dependent; however, how it is forwarded and how +one interacts with it is specified in this protocol. The connection +to the agent is normally automatically forwarded over the secure +channel. + +A program that wishes to use the agent first opens a connection to its +local representative (typically, the agent itself or an SSH server). +It then writes a request to the connection, and waits for response. +It is recommended that at least five minutes of timeout are provided +waiting for the agent to respond to an authentication challenge (this +gives sufficient time for the user to cut-and-paste the challenge to a +separate machine, perform the computation there, and cut-and-paste the +result back if so desired). + +Messages sent to and by the agent are in the following format: +.TS +; +l l. +4 bytes Length, msb first. Does not include length itself. +1 byte Packet type. The value 255 is reserved for future extensions. +data Any data, depending on packet type. Encoding as in the ssh packet +protocol. +.TE + +The following message types are currently defined: +.IP "1 SSH_AGENTC_REQUEST_RSA_IDENTITIES" + +(no arguments) + +Requests the agent to send a list of all RSA keys for which it can +answer a challenge. +.IP "2 SSH_AGENT_RSA_IDENTITIES_ANSWER" +.TS +; +l l. +32-bit int howmany +howmany times: +32-bit int bits +mp-int public exponent +mp-int public modulus +string comment +.TE +The agent sends this message in response to the to +SSH_AGENTC_REQUEST_RSA_IDENTITIES. The answer lists all RSA keys for +which the agent can answer a challenge. The comment field is intended +to help identify each key; it may be printed by an application to +indicate which key is being used. If the agent is not holding any +keys, howmany will be zero. +.IP "3 SSH_AGENTC_RSA_CHALLENGE +.TS +; +l l. +32-bit int bits +mp-int public exponent +mp-int public modulus +mp-int challenge +16 bytes session_id +32-bit int response_type +.TE +Requests RSA decryption of random challenge to authenticate the other +side. The challenge will be decrypted with the RSA private key +corresponding to the given public key. + +The decrypted challenge must contain a zero in the highest (partial) +byte, 2 in the next byte, followed by non-zero random bytes, a zero +byte, and then the real challenge value in the lowermost bytes. The +real challenge must be 32 8-bit bytes (256 bits). + +Response_type indicates the format of the response to be returned. +Currently the only supported value is 1, which means to compute MD5 of +the real challenge plus session id, and return the resulting 16 bytes +in a SSH_AGENT_RSA_RESPONSE message. +.IP "4 SSH_AGENT_RSA_RESPONSE" +.TS +; +l l. +16 bytes MD5 of decrypted challenge +.TE +Answers an RSA authentication challenge. The response is 16 bytes: +the MD5 checksum of the 32-byte challenge. +.IP "5 SSH_AGENT_FAILURE" + +(no arguments) + +This message is sent whenever the agent fails to answer a request +properly. For example, if the agent cannot answer a challenge (e.g., +no longer has the proper key), it can respond with this. The agent +also responds with this message if it receives a message it does not +recognize. +.IP "6 SSH_AGENT_SUCCESS" + +(no arguments) + +This message is sent by the agent as a response to certain requests +that do not otherwise cause a message be sent. Currently, this is +only sent in response to SSH_AGENTC_ADD_RSA_IDENTITY and +SSH_AGENTC_REMOVE_RSA_IDENTITY. +.IP "7 SSH_AGENTC_ADD_RSA_IDENTITY" +.TS +; +l l. +32-bit int bits +mp-int public modulus +mp-int public exponent +mp-int private exponent +mp-int multiplicative inverse of p mod q +mp-int p +mp-int q +string comment +.TE +Registers an RSA key with the agent. After this request, the agent can +use this RSA key to answer requests. The agent responds with +SSH_AGENT_SUCCESS or SSH_AGENT_FAILURE. +.IP "8 SSH_AGENT_REMOVE_RSA_IDENTITY" +.TS +; +l l. +32-bit int bits +mp-int public exponent +mp-int public modulus +.TE +Removes an RSA key from the agent. The agent will no longer accept +challenges for this key and will not list it as a supported identity. +The agent responds with SSH_AGENT_SUCCESS or SSH_AGENT_FAILURE. +.RT + +If the agent receives a message that it does not understand, it +responds with SSH_AGENT_FAILURE. This permits compatible future +extensions. + +It is possible that several clients have a connection open to the +authentication agent simultaneously. Each client will use a separate +connection (thus, any SSH connection can have multiple agent +connections active simultaneously). + + +.ti 0 +References + +.IP "[DES] " +FIPS PUB 46-1: Data Encryption Standard. National Bureau of +Standards, January 1988. FIPS PUB 81: DES Modes of Operation. +National Bureau of Standards, December 1980. Bruce Schneier: Applied +Cryptography. John Wiley & Sons, 1994. J. Seberry and J. Pieprzyk: +Cryptography: An Introduction to Computer Security. Prentice-Hall, +1989. +.IP "[GZIP] " +The GNU GZIP program; available for anonymous ftp at prep.ai.mit.edu. +Please let me know if you know a paper describing the algorithm. +.IP "[IDEA] " +Xuejia Lai: On the Design and Security of Block Ciphers, ETH Series in +Information Processing, vol. 1, Hartung-Gorre Verlag, Konstanz, +Switzerland, 1992. Bruce Schneier: Applied Cryptography, John Wiley & +Sons, 1994. See also the following patents: PCT/CH91/00117, EP 0 482 +154 B1, US Pat. 5,214,703. +.IP [PKCS#1] +PKCS #1: RSA Encryption Standard. Version 1.5, RSA Laboratories, +November 1993. Available for anonymous ftp at ftp.rsa.com. +.IP [POSIX] +Portable Operating System Interface (POSIX) - Part 1: Application +Program Interface (API) [C language], ISO/IEC 9945-1, IEEE Std 1003.1, +1990. +.IP [RFC0791] +J. Postel: Internet Protocol, RFC 791, USC/ISI, September 1981. +.IP [RFC0793] +J. Postel: Transmission Control Protocol, RFC 793, USC/ISI, September +1981. +.IP [RFC1034] +P. Mockapetris: Domain Names - Concepts and Facilities, RFC 1034, +USC/ISI, November 1987. +.IP [RFC1282] +B. Kantor: BSD Rlogin, RFC 1258, UCSD, December 1991. +.IP "[RSA] " +Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1994. See +also R. Rivest, A. Shamir, and L. M. Adleman: Cryptographic +Communications System and Method. US Patent 4,405,829, 1983. +.IP "[X11] " +R. Scheifler: X Window System Protocol, X Consortium Standard, Version +11, Release 6. Massachusetts Institute of Technology, Laboratory of +Computer Science, 1994. +.RT + + +.ti 0 +Security Considerations + +This protocol deals with the very issue of user authentication and +security. + +First of all, as an implementation issue, the server program will have +to run as root (or equivalent) on the server machine. This is because +the server program will need be able to change to an arbitrary user +id. The server must also be able to create a privileged TCP/IP port. + +The client program will need to run as root if any variant of .rhosts +authentication is to be used. This is because the client program will +need to create a privileged port. The client host key is also usually +stored in a file which is readable by root only. The client needs the +host key in .rhosts authentication only. Root privileges can be +dropped as soon as the privileged port has been created and the host +key has been read. + +The SSH protocol offers major security advantages over existing telnet +and rlogin protocols. +.IP o +IP spoofing is restricted to closing a connection (by encryption, host +keys, and the special random cookie). If encryption is not used, IP +spoofing is possible for those who can hear packets going out from the +server. +.IP o +DNS spoofing is made ineffective (by host keys). +.IP o +Routing spoofing is made ineffective (by host keys). +.IP o +All data is encrypted with strong algorithms to make eavesdropping as +difficult as possible. This includes encrypting any authentication +information such as passwords. The information for decrypting session +keys is destroyed every hour. +.IP o +Strong authentication methods: .rhosts combined with RSA host +authentication, and pure RSA authentication. +.IP o +X11 connections and arbitrary TCP/IP ports can be forwarded securely. +.IP o +Man-in-the-middle attacks are deterred by using the server host key to +encrypt the session key. +.IP o +Trojan horses to catch a password by routing manipulation are deterred +by checking that the host key of the server machine matches that +stored on the client host. +.RT + +The security of SSH against man-in-the-middle attacks and the security +of the new form of .rhosts authentication, as well as server host +validation, depends on the integrity of the host key and the files +containing known host keys. + +The host key is normally stored in a root-readable file. If the host +key is compromised, it permits attackers to use IP, DNS and routing +spoofing as with current rlogin and rsh. It should never be any worse +than the current situation. + +The files containing known host keys are not sensitive. However, if an +attacker gets to modify the known host key files, it has the same +consequences as a compromised host key, because the attacker can then +change the recorded host key. + +The security improvements obtained by this protocol for X11 are of +particular significance. Previously, there has been no way to protect +data communicated between an X server and a client running on a remote +machine. By creating a fake display on the server, and forwarding all +X11 requests over the secure channel, SSH can be used to run any X11 +applications securely without any cooperation with the vendors of the +X server or the application. + +Finally, the security of this program relies on the strength of the +underlying cryptographic algorithms. The RSA algorithm is used for +authentication key exchange. It is widely believed to be secure. Of +the algorithms used to encrypt the session, DES has a rather small key +these days, probably permitting governments and organized criminals to +break it in very short time with specialized hardware. 3DES is +probably safe (but slower). IDEA is widely believed to be secure. +People have varying degrees of confidence in the other algorithms. +This program is not secure if used with no encryption at all. + + +.ti 0 +Additional Information + +Additional information (especially on the implementation and mailing +lists) is available via WWW at http://www.cs.hut.fi/ssh. + +Comments should be sent to Tatu Ylonen or the SSH +Mailing List . + +.ti 0 +Author's Address + +.TS +; +l. +Tatu Ylonen +Helsinki University of Technology +Otakaari 1 +FIN-02150 Espoo, Finland + +Phone: +358-0-451-3374 +Fax: +358-0-451-3293 +EMail: ylo@cs.hut.fi +.TE diff --git a/auth-krb4.c b/auth-krb4.c new file mode 100644 index 00000000..735b2053 --- /dev/null +++ b/auth-krb4.c @@ -0,0 +1,209 @@ +/* + + auth-kerberos.c + + Dug Song + + Kerberos v4 authentication and ticket-passing routines. + + $Id$ +*/ + +#include "includes.h" +#include "packet.h" +#include "xmalloc.h" +#include "ssh.h" + +#ifdef KRB4 +int ssh_tf_init(uid_t uid) +{ + extern char *ticket; + char *tkt_root = TKT_ROOT; + struct stat st; + int fd; + + /* Set unique ticket string manually since we're still root. */ + ticket = xmalloc(MAXPATHLEN); +#ifdef AFS + if (lstat("/ticket", &st) != -1) + tkt_root = "/ticket/"; +#endif /* AFS */ + snprintf(ticket, MAXPATHLEN, "%s%d_%d", tkt_root, uid, getpid()); + (void) krb_set_tkt_string(ticket); + + /* Make sure we own this ticket file, and we created it. */ + if (lstat(ticket, &st) == -1 && errno == ENOENT) { + /* good, no ticket file exists. create it. */ + if ((fd = open(ticket, O_RDWR|O_CREAT|O_EXCL, 0600)) != -1) { + close(fd); + return 1; + } + } + else { + /* file exists. make sure server_user owns it (e.g. just passed ticket), + and that it isn't a symlink, and that it is mode 600. */ + if (st.st_mode == (S_IFREG|S_IRUSR|S_IWUSR) && st.st_uid == uid) + return 1; + } + /* Failure. */ + log("WARNING: bad ticket file %s", ticket); + return 0; +} + +int auth_krb4(const char *server_user, KTEXT auth, char **client) +{ + AUTH_DAT adat = { 0 }; + KTEXT_ST reply; + char instance[INST_SZ]; + int r, s; + u_int cksum; + Key_schedule schedule; + struct sockaddr_in local, foreign; + + s = packet_get_connection_in(); + + r = sizeof(local); + memset(&local, 0, sizeof(local)); + if (getsockname(s, (struct sockaddr *) &local, &r) < 0) + debug("getsockname failed: %.100s", strerror(errno)); + r = sizeof(foreign); + memset(&foreign, 0, sizeof(foreign)); + if (getpeername(s, (struct sockaddr *)&foreign, &r) < 0) + debug("getpeername failed: %.100s", strerror(errno)); + + instance[0] = '*'; instance[1] = 0; + + /* Get the encrypted request, challenge, and session key. */ + if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) { + packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]); + return 0; + } + des_key_sched((des_cblock *)adat.session, schedule); + + *client = xmalloc(MAX_K_NAME_SZ); + (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname, + *adat.pinst ? "." : "", adat.pinst, adat.prealm); + + /* Check ~/.klogin authorization now. */ + if (kuserok(&adat, (char *)server_user) != KSUCCESS) { + packet_send_debug("Kerberos V4 .klogin authorization failed!"); + log("Kerberos V4 .klogin authorization failed for %s to account %s", + *client, server_user); + return 0; + } + /* Increment the checksum, and return it encrypted with the session key. */ + cksum = adat.checksum + 1; + cksum = htonl(cksum); + + /* If we can't successfully encrypt the checksum, we send back an empty + message, admitting our failure. */ + if ((r = krb_mk_priv((u_char *)&cksum, reply.dat, sizeof(cksum)+1, + schedule, &adat.session, &local, &foreign)) < 0) { + packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]); + reply.dat[0] = 0; + reply.length = 0; + } + else + reply.length = r; + + /* Clear session key. */ + memset(&adat.session, 0, sizeof(&adat.session)); + + packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE); + packet_put_string((char *) reply.dat, reply.length); + packet_send(); + packet_write_wait(); + return 1; +} +#endif /* KRB4 */ + +#ifdef AFS +int auth_kerberos_tgt(struct passwd *pw, const char *string) +{ + CREDENTIALS creds; + extern char *ticket; + int r; + + if (!radix_to_creds(string, &creds)) { + log("Protocol error decoding Kerberos V4 tgt"); + packet_send_debug("Protocol error decoding Kerberos V4 tgt"); + goto auth_kerberos_tgt_failure; + } + if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ + strlcpy(creds.service, "krbtgt", sizeof creds.service); + + if (strcmp(creds.service, "krbtgt")) { + log("Kerberos V4 tgt (%s%s%s@%s) rejected for uid %d", + creds.pname, creds.pinst[0] ? "." : "", creds.pinst, creds.realm, + pw->pw_uid); + packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for uid %d", + creds.pname, creds.pinst[0] ? "." : "", creds.pinst, + creds.realm, pw->pw_uid); + goto auth_kerberos_tgt_failure; + } + if (!ssh_tf_init(pw->pw_uid) || + (r = in_tkt(creds.pname, creds.pinst)) || + (r = save_credentials(creds.service, creds.instance, creds.realm, + creds.session, creds.lifetime, creds.kvno, + &creds.ticket_st, creds.issue_date))) { + xfree(ticket); + ticket = NULL; + packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials"); + goto auth_kerberos_tgt_failure; + } + /* Successful authentication, passed all checks. */ + chown(ticket, pw->pw_uid, pw->pw_gid); + packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)", + creds.service, creds.instance, creds.realm, + creds.pname, creds.pinst[0] ? "." : "", + creds.pinst, creds.realm); + + packet_start(SSH_SMSG_SUCCESS); + packet_send(); + packet_write_wait(); + return 1; + +auth_kerberos_tgt_failure: + memset(&creds, 0, sizeof(creds)); + packet_start(SSH_SMSG_FAILURE); + packet_send(); + packet_write_wait(); + return 0; +} + +int auth_afs_token(char *server_user, uid_t uid, const char *string) +{ + CREDENTIALS creds; + + if (!radix_to_creds(string, &creds)) { + log("Protocol error decoding AFS token"); + packet_send_debug("Protocol error decoding AFS token"); + packet_start(SSH_SMSG_FAILURE); + packet_send(); + packet_write_wait(); + return 0; + } + if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ + strlcpy(creds.service, "afs", sizeof creds.service); + + if (strncmp(creds.pname, "AFS ID ", 7) == 0) + uid = atoi(creds.pname + 7); + + if (kafs_settoken(creds.realm, uid, &creds)) { + log("AFS token (%s@%s) rejected for uid %d", creds.pname, + creds.realm, uid); + packet_send_debug("AFS token (%s@%s) rejected for uid %d", creds.pname, + creds.realm, uid); + packet_start(SSH_SMSG_FAILURE); + packet_send(); + packet_write_wait(); + return 0; + } + packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service, + creds.realm, creds.pname, creds.realm); + packet_start(SSH_SMSG_SUCCESS); + packet_send(); + packet_write_wait(); + return 1; +} +#endif /* AFS */ diff --git a/auth-passwd.c b/auth-passwd.c new file mode 100644 index 00000000..a1cffba3 --- /dev/null +++ b/auth-passwd.c @@ -0,0 +1,209 @@ +/* + +auth-passwd.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Mar 18 05:11:38 1995 ylo + +Password authentication. This file contains the functions to check whether +the password is valid for the user. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "packet.h" +#include "ssh.h" +#include "servconf.h" +#include "xmalloc.h" + +#ifdef KRB4 +extern char *ticket; +#endif /* KRB4 */ + +#ifdef HAVE_PAM +#include +extern pam_handle_t *pamh; +extern int retval; +extern char* pampasswd; +extern int origretval; +#endif /* HAVE_PAM */ + +/* Tries to authenticate the user using password. Returns true if + authentication succeeds. */ + +int auth_password(struct passwd *pw, const char *password) +{ + extern ServerOptions options; + char *encrypted_password; + + if (pw->pw_uid == 0 && options.permit_root_login == 2) + { + /*packet_send_debug("Server does not permit root login with password.");*/ + return 0; + } + + if (*password == '\0' && options.permit_empty_passwd == 0) + { + /*packet_send_debug("Server does not permit empty password login.");*/ + return 0; + } + + /* deny if no user. */ + if (pw == NULL) + return 0; + +#ifdef HAVE_PAM + retval = origretval; + + pampasswd = xstrdup(password); + + if (retval == PAM_SUCCESS) + retval = pam_authenticate ((pam_handle_t *)pamh, 0); + + if (retval == PAM_SUCCESS) + retval = pam_acct_mgmt ((pam_handle_t *)pamh, 0); + + xfree(pampasswd); + + if (retval == PAM_SUCCESS) + retval = pam_open_session ((pam_handle_t *)pamh, 0); + + return (retval == PAM_SUCCESS); + +#else /* HAVE_PAM */ + +#ifdef SKEY + if (options.skey_authentication == 1) { + if (strncasecmp(password, "s/key", 5) == 0) { + char *skeyinfo = skey_keyinfo(pw->pw_name); + if(skeyinfo == NULL){ + debug("generating fake skeyinfo for %.100s.", pw->pw_name); + skeyinfo = skey_fake_keyinfo(pw->pw_name); + } + if(skeyinfo != NULL) + packet_send_debug(skeyinfo); + /* Try again. */ + return 0; + } + else if (skey_haskey(pw->pw_name) == 0 && + skey_passcheck(pw->pw_name, (char *)password) != -1) { + /* Authentication succeeded. */ + return 1; + } + /* Fall back to ordinary passwd authentication. */ + } +#endif + +#if defined(KRB4) + /* Support for Kerberos v4 authentication - Dug Song */ + if (options.kerberos_authentication) + { + AUTH_DAT adata; + KTEXT_ST tkt; + struct hostent *hp; + unsigned long faddr; + char localhost[MAXHOSTNAMELEN]; /* local host name */ + char phost[INST_SZ]; /* host instance */ + char realm[REALM_SZ]; /* local Kerberos realm */ + int r; + + /* Try Kerberos password authentication only for non-root + users and only if Kerberos is installed. */ + if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) { + + /* Set up our ticket file. */ + if (!ssh_tf_init(pw->pw_uid)) { + log("Couldn't initialize Kerberos ticket file for %s!", + pw->pw_name); + goto kerberos_auth_failure; + } + /* Try to get TGT using our password. */ + r = krb_get_pw_in_tkt((char *)pw->pw_name, "", realm, "krbtgt", realm, + DEFAULT_TKT_LIFE, (char *)password); + if (r != INTK_OK) { + packet_send_debug("Kerberos V4 password authentication for %s " + "failed: %s", pw->pw_name, krb_err_txt[r]); + goto kerberos_auth_failure; + } + /* Successful authentication. */ + chown(ticket, pw->pw_uid, pw->pw_gid); + + (void) gethostname(localhost, sizeof(localhost)); + (void) strlcpy(phost, (char *)krb_get_phost(localhost), INST_SZ); + + /* Now that we have a TGT, try to get a local "rcmd" ticket to + ensure that we are not talking to a bogus Kerberos server. */ + r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33); + + if (r == KSUCCESS) { + if (!(hp = gethostbyname(localhost))) { + log("Couldn't get local host address!"); + goto kerberos_auth_failure; + } + memmove((void *)&faddr, (void *)hp->h_addr, sizeof(faddr)); + + /* Verify our "rcmd" ticket. */ + r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost, faddr, &adata, ""); + if (r == RD_AP_UNDEC) { + /* Probably didn't have a srvtab on localhost. Allow login. */ + log("Kerberos V4 TGT for %s unverifiable, no srvtab installed? " + "krb_rd_req: %s", pw->pw_name, krb_err_txt[r]); + } + else if (r != KSUCCESS) { + log("Kerberos V4 %s ticket unverifiable: %s", + KRB4_SERVICE_NAME, krb_err_txt[r]); + goto kerberos_auth_failure; + } + } + else if (r == KDC_PR_UNKNOWN) { + /* Allow login if no rcmd service exists, but log the error. */ + log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s " + "not registered, or srvtab is wrong?", pw->pw_name, + krb_err_txt[r], KRB4_SERVICE_NAME, phost); + } + else { + /* TGT is bad, forget it. Possibly spoofed! */ + packet_send_debug("WARNING: Kerberos V4 TGT possibly spoofed for" + "%s: %s", pw->pw_name, krb_err_txt[r]); + goto kerberos_auth_failure; + } + + /* Authentication succeeded. */ + return 1; + + kerberos_auth_failure: + (void) dest_tkt(); + xfree(ticket); + ticket = NULL; + if (!options.kerberos_or_local_passwd ) return 0; + } + else { + /* Logging in as root or no local Kerberos realm. */ + packet_send_debug("Unable to authenticate to Kerberos."); + } + /* Fall back to ordinary passwd authentication. */ + } +#endif /* KRB4 */ + + /* Check for users with no password. */ + if (strcmp(password, "") == 0 && strcmp(pw->pw_passwd, "") == 0) + { + packet_send_debug("Login permitted without a password because the account has no password."); + return 1; /* The user has no password and an empty password was tried. */ + } + + /* Encrypt the candidate password using the proper salt. */ + encrypted_password = crypt(password, + (pw->pw_passwd[0] && pw->pw_passwd[1]) ? + pw->pw_passwd : "xx"); + + /* Authentication is accepted if the encrypted passwords are identical. */ + return (strcmp(encrypted_password, pw->pw_passwd) == 0); +#endif /* HAVE_PAM */ +} diff --git a/auth-rh-rsa.c b/auth-rh-rsa.c new file mode 100644 index 00000000..9c71715e --- /dev/null +++ b/auth-rh-rsa.c @@ -0,0 +1,83 @@ +/* + +auth-rh-rsa.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sun May 7 03:08:06 1995 ylo + +Rhosts or /etc/hosts.equiv authentication combined with RSA host +authentication. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "packet.h" +#include "ssh.h" +#include "xmalloc.h" +#include "uidswap.h" + +/* Tries to authenticate the user using the .rhosts file and the host using + its host key. Returns true if authentication succeeds. + .rhosts and .shosts will be ignored if ignore_rhosts is non-zero. */ + +int auth_rhosts_rsa(struct passwd *pw, const char *client_user, + unsigned int client_host_key_bits, + BIGNUM *client_host_key_e, BIGNUM *client_host_key_n, + int ignore_rhosts, int strict_modes) +{ + const char *canonical_hostname; + HostStatus host_status; + BIGNUM *ke, *kn; + + debug("Trying rhosts with RSA host authentication for %.100s", client_user); + + /* Check if we would accept it using rhosts authentication. */ + if (!auth_rhosts(pw, client_user, ignore_rhosts, strict_modes)) + return 0; + + canonical_hostname = get_canonical_hostname(); + + debug("Rhosts RSA authentication: canonical host %.900s", + canonical_hostname); + + /* Check if we know the host and its host key. */ + /* Check system-wide host file. */ + ke = BN_new(); + kn = BN_new(); + host_status = check_host_in_hostfile(SSH_SYSTEM_HOSTFILE, canonical_hostname, + client_host_key_bits, client_host_key_e, + client_host_key_n, ke, kn); + BN_free(ke); + BN_free(kn); + if (host_status != HOST_OK) { + /* The host key was not found. */ + debug("Rhosts with RSA host authentication denied: unknown or invalid host key"); + packet_send_debug("Your host key cannot be verified: unknown or invalid host key."); + return 0; + } + + /* A matching host key was found and is known. */ + + /* Perform the challenge-response dialog with the client for the host key. */ + if (!auth_rsa_challenge_dialog(client_host_key_bits, + client_host_key_e, client_host_key_n)) + { + log("Client on %.800s failed to respond correctly to host authentication.", + canonical_hostname); + return 0; + } + + /* We have authenticated the user using .rhosts or /etc/hosts.equiv, and + the host using RSA. We accept the authentication. */ + + log("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.", + pw->pw_name, client_user, canonical_hostname); + packet_send_debug("Rhosts with RSA host authentication accepted."); + return 1; +} diff --git a/auth-rhosts.c b/auth-rhosts.c new file mode 100644 index 00000000..62c64c0a --- /dev/null +++ b/auth-rhosts.c @@ -0,0 +1,298 @@ +/* + +auth-rhosts.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Fri Mar 17 05:12:18 1995 ylo + +Rhosts authentication. This file contains code to check whether to admit +the login based on rhosts authentication. This file also processes +/etc/hosts.equiv. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "packet.h" +#include "ssh.h" +#include "xmalloc.h" +#include "uidswap.h" + +/* This function processes an rhosts-style file (.rhosts, .shosts, or + /etc/hosts.equiv). This returns true if authentication can be granted + based on the file, and returns zero otherwise. */ + +int check_rhosts_file(const char *filename, const char *hostname, + const char *ipaddr, const char *client_user, + const char *server_user) +{ + FILE *f; + char buf[1024]; /* Must not be larger than host, user, dummy below. */ + + /* Open the .rhosts file. */ + f = fopen(filename, "r"); + if (!f) + return 0; /* Cannot read the .rhosts - deny access. */ + + /* Go through the file, checking every entry. */ + while (fgets(buf, sizeof(buf), f)) + { + /* All three must be at least as big as buf to avoid overflows. */ + char hostbuf[1024], userbuf[1024], dummy[1024], *host, *user, *cp; + int negated; + + for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) + ; + if (*cp == '#' || *cp == '\n' || !*cp) + continue; + + /* NO_PLUS is supported at least on OSF/1. We skip it (we don't ever + support the plus syntax). */ + if (strncmp(cp, "NO_PLUS", 7) == 0) + continue; + + /* This should be safe because each buffer is as big as the whole + string, and thus cannot be overwritten. */ + switch (sscanf(buf, "%s %s %s", hostbuf, userbuf, dummy)) + { + case 0: + packet_send_debug("Found empty line in %.100s.", filename); + continue; /* Empty line? */ + case 1: + /* Host name only. */ + strlcpy(userbuf, server_user, sizeof(userbuf)); + break; + case 2: + /* Got both host and user name. */ + break; + case 3: + packet_send_debug("Found garbage in %.100s.", filename); + continue; /* Extra garbage */ + default: + continue; /* Weird... */ + } + + host = hostbuf; + user = userbuf; + negated = 0; + + /* Process negated host names, or positive netgroups. */ + if (host[0] == '-') + { + negated = 1; + host++; + } + else + if (host[0] == '+') + host++; + + if (user[0] == '-') + { + negated = 1; + user++; + } + else + if (user[0] == '+') + user++; + + /* Check for empty host/user names (particularly '+'). */ + if (!host[0] || !user[0]) + { + /* We come here if either was '+' or '-'. */ + packet_send_debug("Ignoring wild host/user names in %.100s.", + filename); + continue; + } + + /* Verify that host name matches. */ + if (host[0] == '@') + { + if (!innetgr(host + 1, hostname, NULL, NULL) && + !innetgr(host + 1, ipaddr, NULL, NULL)) + continue; + } + else + if (strcasecmp(host, hostname) && strcmp(host, ipaddr) != 0) + continue; /* Different hostname. */ + + /* Verify that user name matches. */ + if (user[0] == '@') + { + if (!innetgr(user + 1, NULL, client_user, NULL)) + continue; + } + else + if (strcmp(user, client_user) != 0) + continue; /* Different username. */ + + /* Found the user and host. */ + fclose(f); + + /* If the entry was negated, deny access. */ + if (negated) + { + packet_send_debug("Matched negative entry in %.100s.", + filename); + return 0; + } + + /* Accept authentication. */ + return 1; + } + + /* Authentication using this file denied. */ + fclose(f); + return 0; +} + +/* Tries to authenticate the user using the .shosts or .rhosts file. + Returns true if authentication succeeds. If ignore_rhosts is + true, only /etc/hosts.equiv will be considered (.rhosts and .shosts + are ignored). */ + +int auth_rhosts(struct passwd *pw, const char *client_user, + int ignore_rhosts, int strict_modes) +{ + char buf[1024]; + const char *hostname, *ipaddr; + int port; + struct stat st; + static const char *rhosts_files[] = { ".shosts", ".rhosts", NULL }; + unsigned int rhosts_file_index; + + /* Quick check: if the user has no .shosts or .rhosts files, return failure + immediately without doing costly lookups from name servers. */ + /* Switch to the user's uid. */ + temporarily_use_uid(pw->pw_uid); + for (rhosts_file_index = 0; rhosts_files[rhosts_file_index]; + rhosts_file_index++) + { + /* Check users .rhosts or .shosts. */ + snprintf(buf, sizeof buf, "%.500s/%.100s", + pw->pw_dir, rhosts_files[rhosts_file_index]); + if (stat(buf, &st) >= 0) + break; + } + /* Switch back to privileged uid. */ + restore_uid(); + + if (!rhosts_files[rhosts_file_index] && stat("/etc/hosts.equiv", &st) < 0 && + stat(SSH_HOSTS_EQUIV, &st) < 0) + return 0; /* The user has no .shosts or .rhosts file and there are no + system-wide files. */ + + /* Get the name, address, and port of the remote host. */ + hostname = get_canonical_hostname(); + ipaddr = get_remote_ipaddr(); + port = get_remote_port(); + + /* Check that the connection comes from a privileged port. + Rhosts authentication only makes sense for priviledged programs. + Of course, if the intruder has root access on his local machine, + he can connect from any port. So do not use .rhosts + authentication from machines that you do not trust. */ + if (port >= IPPORT_RESERVED || + port < IPPORT_RESERVED / 2) + { + log("Connection from %.100s from nonpriviledged port %d", + hostname, port); + packet_send_debug("Your ssh client is not running as root."); + return 0; + } + + /* If not logging in as superuser, try /etc/hosts.equiv and shosts.equiv. */ + if (pw->pw_uid != 0) + { + if (check_rhosts_file("/etc/hosts.equiv", hostname, ipaddr, client_user, + pw->pw_name)) + { + packet_send_debug("Accepted for %.100s [%.100s] by /etc/hosts.equiv.", + hostname, ipaddr); + return 1; + } + if (check_rhosts_file(SSH_HOSTS_EQUIV, hostname, ipaddr, client_user, + pw->pw_name)) + { + packet_send_debug("Accepted for %.100s [%.100s] by %.100s.", + hostname, ipaddr, SSH_HOSTS_EQUIV); + return 1; + } + } + + /* Check that the home directory is owned by root or the user, and is not + group or world writable. */ + if (stat(pw->pw_dir, &st) < 0) + { + log("Rhosts authentication refused for %.100: no home directory %.200s", + pw->pw_name, pw->pw_dir); + packet_send_debug("Rhosts authentication refused for %.100: no home directory %.200s", + pw->pw_name, pw->pw_dir); + return 0; + } + if (strict_modes && + ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || + (st.st_mode & 022) != 0)) + { + log("Rhosts authentication refused for %.100s: bad ownership or modes for home directory.", + pw->pw_name); + packet_send_debug("Rhosts authentication refused for %.100s: bad ownership or modes for home directory.", + pw->pw_name); + return 0; + } + + /* Check all .rhosts files (currently .shosts and .rhosts). */ + /* Temporarily use the user's uid. */ + temporarily_use_uid(pw->pw_uid); + for (rhosts_file_index = 0; rhosts_files[rhosts_file_index]; + rhosts_file_index++) + { + /* Check users .rhosts or .shosts. */ + snprintf(buf, sizeof buf, "%.500s/%.100s", + pw->pw_dir, rhosts_files[rhosts_file_index]); + if (stat(buf, &st) < 0) + continue; /* No such file. */ + + /* Make sure that the file is either owned by the user or by root, + and make sure it is not writable by anyone but the owner. This is + to help avoid novices accidentally allowing access to their account + by anyone. */ + if (strict_modes && + ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || + (st.st_mode & 022) != 0)) + { + log("Rhosts authentication refused for %.100s: bad modes for %.200s", + pw->pw_name, buf); + packet_send_debug("Bad file modes for %.200s", buf); + continue; + } + + /* Check if we have been configured to ignore .rhosts and .shosts + files. */ + if (ignore_rhosts) + { + packet_send_debug("Server has been configured to ignore %.100s.", + rhosts_files[rhosts_file_index]); + continue; + } + + /* Check if authentication is permitted by the file. */ + if (check_rhosts_file(buf, hostname, ipaddr, client_user, pw->pw_name)) + { + packet_send_debug("Accepted by %.100s.", + rhosts_files[rhosts_file_index]); + /* Restore the privileged uid. */ + restore_uid(); + return 1; + } + } + + /* Rhosts authentication denied. */ + /* Restore the privileged uid. */ + restore_uid(); + return 0; +} diff --git a/auth-rsa.c b/auth-rsa.c new file mode 100644 index 00000000..1c219686 --- /dev/null +++ b/auth-rsa.c @@ -0,0 +1,478 @@ +/* + +auth-rsa.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Mon Mar 27 01:46:52 1995 ylo + +RSA-based authentication. This code determines whether to admit a login +based on RSA authentication. This file also contains functions to check +validity of the host key. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "rsa.h" +#include "packet.h" +#include "xmalloc.h" +#include "ssh.h" +#include "mpaux.h" +#include "uidswap.h" + +#include +#include + +/* Flags that may be set in authorized_keys options. */ +extern int no_port_forwarding_flag; +extern int no_agent_forwarding_flag; +extern int no_x11_forwarding_flag; +extern int no_pty_flag; +extern char *forced_command; +extern struct envstring *custom_environment; + +/* Session identifier that is used to bind key exchange and authentication + responses to a particular session. */ +extern unsigned char session_id[16]; + +/* The .ssh/authorized_keys file contains public keys, one per line, in the + following format: + options bits e n comment + where bits, e and n are decimal numbers, + and comment is any string of characters up to newline. The maximum + length of a line is 8000 characters. See the documentation for a + description of the options. +*/ + +/* Performs the RSA authentication challenge-response dialog with the client, + and returns true (non-zero) if the client gave the correct answer to + our challenge; returns zero if the client gives a wrong answer. */ + +int +auth_rsa_challenge_dialog(unsigned int bits, BIGNUM *e, BIGNUM *n) +{ + BIGNUM *challenge, *encrypted_challenge, *aux; + RSA *pk; + BN_CTX *ctx = BN_CTX_new(); + unsigned char buf[32], mdbuf[16], response[16]; + MD5_CTX md; + unsigned int i; + int plen, len; + + encrypted_challenge = BN_new(); + challenge = BN_new(); + aux = BN_new(); + + /* Generate a random challenge. */ + BN_rand(challenge, 256, 0, 0); + BN_mod(challenge, challenge, n, ctx); + + /* Create the public key data structure. */ + pk = RSA_new(); + pk->e = BN_new(); + BN_copy(pk->e, e); + pk->n = BN_new(); + BN_copy(pk->n, n); + + /* Encrypt the challenge with the public key. */ + rsa_public_encrypt(encrypted_challenge, challenge, pk); + RSA_free(pk); + + /* Send the encrypted challenge to the client. */ + packet_start(SSH_SMSG_AUTH_RSA_CHALLENGE); + packet_put_bignum(encrypted_challenge); + packet_send(); + packet_write_wait(); + + /* The response is MD5 of decrypted challenge plus session id. */ + len = BN_num_bytes(challenge); + assert(len <= 32 && len); + memset(buf, 0, 32); + BN_bn2bin(challenge, buf + 32 - len); + MD5_Init(&md); + MD5_Update(&md, buf, 32); + MD5_Update(&md, session_id, 16); + MD5_Final(mdbuf, &md); + + /* We will no longer need these. */ + BN_clear_free(encrypted_challenge); + BN_clear_free(challenge); + BN_clear_free(aux); + BN_CTX_free(ctx); + + /* Wait for a response. */ + packet_read_expect(&plen, SSH_CMSG_AUTH_RSA_RESPONSE); + packet_integrity_check(plen, 16, SSH_CMSG_AUTH_RSA_RESPONSE); + for (i = 0; i < 16; i++) + response[i] = packet_get_char(); + + /* Verify that the response is the original challenge. */ + if (memcmp(response, mdbuf, 16) != 0) + { + /* Wrong answer. */ + return 0; + } + + /* Correct answer. */ + return 1; +} + +/* Performs the RSA authentication dialog with the client. This returns + 0 if the client could not be authenticated, and 1 if authentication was + successful. This may exit if there is a serious protocol violation. */ + +int +auth_rsa(struct passwd *pw, BIGNUM *client_n, int strict_modes) +{ + char line[8192]; + int authenticated; + unsigned int bits; + FILE *f; + unsigned long linenum = 0; + struct stat st; + BIGNUM *e, *n; + + /* Temporarily use the user's uid. */ + temporarily_use_uid(pw->pw_uid); + + /* The authorized keys. */ + snprintf(line, sizeof line, "%.500s/%.100s", pw->pw_dir, + SSH_USER_PERMITTED_KEYS); + + /* Fail quietly if file does not exist */ + if (stat(line, &st) < 0) + { + /* Restore the privileged uid. */ + restore_uid(); + return 0; + } + + /* Open the file containing the authorized keys. */ + f = fopen(line, "r"); + if (!f) + { + /* Restore the privileged uid. */ + restore_uid(); + packet_send_debug("Could not open %.900s for reading.", line); + packet_send_debug("If your home is on an NFS volume, it may need to be world-readable."); + return 0; + } + + if (strict_modes) { + int fail=0; + char buf[1024]; + /* Check open file in order to avoid open/stat races */ + if (fstat(fileno(f), &st) < 0 || + (st.st_uid != 0 && st.st_uid != pw->pw_uid) || + (st.st_mode & 022) != 0) { + snprintf(buf, sizeof buf, "RSA authentication refused for %.100s: " + "bad ownership or modes for '%s'.", pw->pw_name, line); + fail=1; + }else{ + /* Check path to SSH_USER_PERMITTED_KEYS */ + int i; + static const char *check[] = { + "", SSH_USER_DIR, NULL + }; + for (i=0; check[i]; i++) { + snprintf(line, sizeof line, "%.500s/%.100s", pw->pw_dir, check[i]); + if (stat(line, &st) < 0 || + (st.st_uid != 0 && st.st_uid != pw->pw_uid) || + (st.st_mode & 022) != 0) { + snprintf(buf, sizeof buf, "RSA authentication refused for %.100s: " + "bad ownership or modes for '%s'.", pw->pw_name, line); + fail=1; + break; + } + } + } + if (fail) { + log(buf); + packet_send_debug(buf); + restore_uid(); + return 0; + } + } + + /* Flag indicating whether authentication has succeeded. */ + authenticated = 0; + + /* Initialize mp-int variables. */ + e = BN_new(); + n = BN_new(); + + /* Go though the accepted keys, looking for the current key. If found, + perform a challenge-response dialog to verify that the user really has + the corresponding private key. */ + while (fgets(line, sizeof(line), f)) + { + char *cp; + char *options; + + linenum++; + + /* Skip leading whitespace. */ + for (cp = line; *cp == ' ' || *cp == '\t'; cp++) + ; + + /* Skip empty and comment lines. */ + if (!*cp || *cp == '\n' || *cp == '#') + continue; + + /* Check if there are options for this key, and if so, save their + starting address and skip the option part for now. If there are no + options, set the starting address to NULL. */ + if (*cp < '0' || *cp > '9') + { + int quoted = 0; + options = cp; + for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) + { + if (*cp == '\\' && cp[1] == '"') + cp++; /* Skip both */ + else + if (*cp == '"') + quoted = !quoted; + } + } + else + options = NULL; + + /* Parse the key from the line. */ + if (!auth_rsa_read_key(&cp, &bits, e, n)) + { + debug("%.100s, line %lu: bad key syntax", + SSH_USER_PERMITTED_KEYS, linenum); + packet_send_debug("%.100s, line %lu: bad key syntax", + SSH_USER_PERMITTED_KEYS, linenum); + continue; + } + /* cp now points to the comment part. */ + + /* Check if the we have found the desired key (identified by its + modulus). */ + if (BN_cmp(n, client_n) != 0) + continue; /* Wrong key. */ + + /* We have found the desired key. */ + + /* Perform the challenge-response dialog for this key. */ + if (!auth_rsa_challenge_dialog(bits, e, n)) + { + /* Wrong response. */ + log("Wrong response to RSA authentication challenge."); + packet_send_debug("Wrong response to RSA authentication challenge."); + continue; + } + + /* Correct response. The client has been successfully authenticated. + Note that we have not yet processed the options; this will be reset + if the options cause the authentication to be rejected. */ + authenticated = 1; + + /* RSA part of authentication was accepted. Now process the options. */ + if (options) + { + while (*options && *options != ' ' && *options != '\t') + { + cp = "no-port-forwarding"; + if (strncmp(options, cp, strlen(cp)) == 0) + { + packet_send_debug("Port forwarding disabled."); + no_port_forwarding_flag = 1; + options += strlen(cp); + goto next_option; + } + cp = "no-agent-forwarding"; + if (strncmp(options, cp, strlen(cp)) == 0) + { + packet_send_debug("Agent forwarding disabled."); + no_agent_forwarding_flag = 1; + options += strlen(cp); + goto next_option; + } + cp = "no-X11-forwarding"; + if (strncmp(options, cp, strlen(cp)) == 0) + { + packet_send_debug("X11 forwarding disabled."); + no_x11_forwarding_flag = 1; + options += strlen(cp); + goto next_option; + } + cp = "no-pty"; + if (strncmp(options, cp, strlen(cp)) == 0) + { + packet_send_debug("Pty allocation disabled."); + no_pty_flag = 1; + options += strlen(cp); + goto next_option; + } + cp = "command=\""; + if (strncmp(options, cp, strlen(cp)) == 0) + { + int i; + options += strlen(cp); + forced_command = xmalloc(strlen(options) + 1); + i = 0; + while (*options) + { + if (*options == '"') + break; + if (*options == '\\' && options[1] == '"') + { + options += 2; + forced_command[i++] = '"'; + continue; + } + forced_command[i++] = *options++; + } + if (!*options) + { + debug("%.100s, line %lu: missing end quote", + SSH_USER_PERMITTED_KEYS, linenum); + packet_send_debug("%.100s, line %lu: missing end quote", + SSH_USER_PERMITTED_KEYS, linenum); + continue; + } + forced_command[i] = 0; + packet_send_debug("Forced command: %.900s", forced_command); + options++; + goto next_option; + } + cp = "environment=\""; + if (strncmp(options, cp, strlen(cp)) == 0) + { + int i; + char *s; + struct envstring *new_envstring; + options += strlen(cp); + s = xmalloc(strlen(options) + 1); + i = 0; + while (*options) + { + if (*options == '"') + break; + if (*options == '\\' && options[1] == '"') + { + options += 2; + s[i++] = '"'; + continue; + } + s[i++] = *options++; + } + if (!*options) + { + debug("%.100s, line %lu: missing end quote", + SSH_USER_PERMITTED_KEYS, linenum); + packet_send_debug("%.100s, line %lu: missing end quote", + SSH_USER_PERMITTED_KEYS, linenum); + continue; + } + s[i] = 0; + packet_send_debug("Adding to environment: %.900s", s); + debug("Adding to environment: %.900s", s); + options++; + new_envstring = xmalloc(sizeof(struct envstring)); + new_envstring->s = s; + new_envstring->next = custom_environment; + custom_environment = new_envstring; + goto next_option; + } + cp = "from=\""; + if (strncmp(options, cp, strlen(cp)) == 0) + { + char *patterns = xmalloc(strlen(options) + 1); + int i; + options += strlen(cp); + i = 0; + while (*options) + { + if (*options == '"') + break; + if (*options == '\\' && options[1] == '"') + { + options += 2; + patterns[i++] = '"'; + continue; + } + patterns[i++] = *options++; + } + if (!*options) + { + debug("%.100s, line %lu: missing end quote", + SSH_USER_PERMITTED_KEYS, linenum); + packet_send_debug("%.100s, line %lu: missing end quote", + SSH_USER_PERMITTED_KEYS, linenum); + continue; + } + patterns[i] = 0; + options++; + if (!match_hostname(get_canonical_hostname(), patterns, + strlen(patterns)) && + !match_hostname(get_remote_ipaddr(), patterns, + strlen(patterns))) + { + log("RSA authentication tried for %.100s with correct key but not from a permitted host (host=%.200s, ip=%.200s).", + pw->pw_name, get_canonical_hostname(), + get_remote_ipaddr()); + packet_send_debug("Your host '%.200s' is not permitted to use this key for login.", + get_canonical_hostname()); + xfree(patterns); + authenticated = 0; + break; + } + xfree(patterns); + /* Host name matches. */ + goto next_option; + } + bad_option: + /* Unknown option. */ + log("Bad options in %.100s file, line %lu: %.50s", + SSH_USER_PERMITTED_KEYS, linenum, options); + packet_send_debug("Bad options in %.100s file, line %lu: %.50s", + SSH_USER_PERMITTED_KEYS, linenum, options); + authenticated = 0; + break; + + next_option: + /* Skip the comma, and move to the next option (or break out + if there are no more). */ + if (!*options) + fatal("Bugs in auth-rsa.c option processing."); + if (*options == ' ' || *options == '\t') + break; /* End of options. */ + if (*options != ',') + goto bad_option; + options++; + /* Process the next option. */ + continue; + } + } + + /* Break out of the loop if authentication was successful; otherwise + continue searching. */ + if (authenticated) + break; + } + + /* Restore the privileged uid. */ + restore_uid(); + + /* Close the file. */ + fclose(f); + + /* Clear any mp-int variables. */ + BN_clear_free(n); + BN_clear_free(e); + + if (authenticated) + packet_send_debug("RSA authentication accepted."); + + /* Return authentication result. */ + return authenticated; +} diff --git a/auth-skey.c b/auth-skey.c new file mode 100644 index 00000000..06f81b89 --- /dev/null +++ b/auth-skey.c @@ -0,0 +1,149 @@ +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include + +/* from %OpenBSD: skeylogin.c,v 1.32 1999/08/16 14:46:56 millert Exp % */ + + +#define ROUND(x) (((x)[0] << 24) + (((x)[1]) << 16) + (((x)[2]) << 8) + \ + ((x)[3])) + +/* + * hash_collapse() + */ +static u_int32_t +hash_collapse(s) + u_char *s; +{ + int len, target; + u_int32_t i; + + if ((strlen(s) % sizeof(u_int32_t)) == 0) + target = strlen(s); /* Multiple of 4 */ + else + target = strlen(s) - (strlen(s) % sizeof(u_int32_t)); + + for (i = 0, len = 0; len < target; len += 4) + i ^= ROUND(s + len); + + return i; +} +char * +skey_fake_keyinfo(char *username) +{ + int i; + u_int ptr; + u_char hseed[SKEY_MAX_SEED_LEN], flg = 1, *up; + char pbuf[SKEY_MAX_PW_LEN+1]; + static char skeyprompt[SKEY_MAX_CHALLENGE+1]; + char *secret = NULL; + size_t secretlen = 0; + SHA1_CTX ctx; + char *p, *u; + + /* + * Base first 4 chars of seed on hostname. + * Add some filler for short hostnames if necessary. + */ + if (gethostname(pbuf, sizeof(pbuf)) == -1) + *(p = pbuf) = '.'; + else + for (p = pbuf; *p && isalnum(*p); p++) + if (isalpha(*p) && isupper(*p)) + *p = tolower(*p); + if (*p && pbuf - p < 4) + (void)strncpy(p, "asjd", 4 - (pbuf - p)); + pbuf[4] = '\0'; + + /* Hash the username if possible */ + if ((up = SHA1Data(username, strlen(username), NULL)) != NULL) { + struct stat sb; + time_t t; + int fd; + + /* Collapse the hash */ + ptr = hash_collapse(up); + memset(up, 0, strlen(up)); + + /* See if the random file's there, else use ctime */ + if ((fd = open(_SKEY_RAND_FILE_PATH_, O_RDONLY)) != -1 + && fstat(fd, &sb) == 0 && + sb.st_size > (off_t)SKEY_MAX_SEED_LEN && + lseek(fd, ptr % (sb.st_size - SKEY_MAX_SEED_LEN), + SEEK_SET) != -1 && read(fd, hseed, + SKEY_MAX_SEED_LEN) == SKEY_MAX_SEED_LEN) { + close(fd); + secret = hseed; + secretlen = SKEY_MAX_SEED_LEN; + flg = 0; + } else if (!stat(_PATH_MEM, &sb) || !stat("/", &sb)) { + t = sb.st_ctime; + secret = ctime(&t); + secretlen = strlen(secret); + flg = 0; + } + } + + /* Put that in your pipe and smoke it */ + if (flg == 0) { + /* Hash secret value with username */ + SHA1Init(&ctx); + SHA1Update(&ctx, secret, secretlen); + SHA1Update(&ctx, username, strlen(username)); + SHA1End(&ctx, up); + + /* Zero out */ + memset(secret, 0, secretlen); + + /* Now hash the hash */ + SHA1Init(&ctx); + SHA1Update(&ctx, up, strlen(up)); + SHA1End(&ctx, up); + + ptr = hash_collapse(up + 4); + + for (i = 4; i < 9; i++) { + pbuf[i] = (ptr % 10) + '0'; + ptr /= 10; + } + pbuf[i] = '\0'; + + /* Sequence number */ + ptr = ((up[2] + up[3]) % 99) + 1; + + memset(up, 0, 20); /* SHA1 specific */ + free(up); + + (void)snprintf(skeyprompt, sizeof skeyprompt, + "otp-%.*s %d %.*s", + SKEY_MAX_HASHNAME_LEN, + skey_get_algorithm(), + ptr, SKEY_MAX_SEED_LEN, + pbuf); + } else { + /* Base last 8 chars of seed on username */ + u = username; + i = 8; + p = &pbuf[4]; + do { + if (*u == 0) { + /* Pad remainder with zeros */ + while (--i >= 0) + *p++ = '0'; + break; + } + + *p++ = (*u++ % 10) + '0'; + } while (--i != 0); + pbuf[12] = '\0'; + + (void)snprintf(skeyprompt, sizeof skeyprompt, + "otp-%.*s %d %.*s", + SKEY_MAX_HASHNAME_LEN, + skey_get_algorithm(), + 99, SKEY_MAX_SEED_LEN, pbuf); + } + return skeyprompt; +} diff --git a/authfd.c b/authfd.c new file mode 100644 index 00000000..fb03facc --- /dev/null +++ b/authfd.c @@ -0,0 +1,565 @@ +/* + +authfd.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Mar 29 01:30:28 1995 ylo + +Functions for connecting the local authentication agent. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include "rsa.h" +#include "authfd.h" +#include "buffer.h" +#include "bufaux.h" +#include "xmalloc.h" +#include "getput.h" + +#include + +/* Returns the number of the authentication fd, or -1 if there is none. */ + +int +ssh_get_authentication_socket() +{ + const char *authsocket; + int sock; + struct sockaddr_un sunaddr; + + authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME); + if (!authsocket) + return -1; + + sunaddr.sun_family = AF_UNIX; + strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path)); + + sock = socket(AF_UNIX, SOCK_STREAM, 0); + if (sock < 0) + return -1; + + if (connect(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) + { + close(sock); + return -1; + } + + return sock; +} + +/* Closes the agent socket if it should be closed (depends on how it was + obtained). The argument must have been returned by + ssh_get_authentication_socket(). */ + +void ssh_close_authentication_socket(int sock) +{ + if (getenv(SSH_AUTHSOCKET_ENV_NAME)) + close(sock); +} + +/* Opens and connects a private socket for communication with the + authentication agent. Returns the file descriptor (which must be + shut down and closed by the caller when no longer needed). + Returns NULL if an error occurred and the connection could not be + opened. */ + +AuthenticationConnection *ssh_get_authentication_connection() +{ + AuthenticationConnection *auth; + int sock; + + sock = ssh_get_authentication_socket(); + + /* Fail if we couldn't obtain a connection. This happens if we exited + due to a timeout. */ + if (sock < 0) + return NULL; + + /* Applocate the connection structure and initialize it. */ + auth = xmalloc(sizeof(*auth)); + auth->fd = sock; + buffer_init(&auth->packet); + buffer_init(&auth->identities); + auth->howmany = 0; + + return auth; +} + +/* Closes the connection to the authentication agent and frees any associated + memory. */ + +void ssh_close_authentication_connection(AuthenticationConnection *ac) +{ + buffer_free(&ac->packet); + buffer_free(&ac->identities); + close(ac->fd); + /* Free the connection data structure. */ + xfree(ac); +} + +/* Returns the first authentication identity held by the agent. + Returns true if an identity is available, 0 otherwise. + The caller must initialize the integers before the call, and free the + comment after a successful call (before calling ssh_get_next_identity). */ + +int +ssh_get_first_identity(AuthenticationConnection *auth, + int *bitsp, BIGNUM *e, BIGNUM *n, char **comment) +{ + unsigned char msg[8192]; + int len, l; + + /* Send a message to the agent requesting for a list of the identities + it can represent. */ + msg[0] = 0; + msg[1] = 0; + msg[2] = 0; + msg[3] = 1; + msg[4] = SSH_AGENTC_REQUEST_RSA_IDENTITIES; + if (write(auth->fd, msg, 5) != 5) + { + error("write auth->fd: %.100s", strerror(errno)); + return 0; + } + + /* Read the length of the response. XXX implement timeouts here. */ + len = 4; + while (len > 0) + { + l = read(auth->fd, msg + 4 - len, len); + if (l <= 0) + { + error("read auth->fd: %.100s", strerror(errno)); + return 0; + } + len -= l; + } + + /* Extract the length, and check it for sanity. (We cannot trust + authentication agents). */ + len = GET_32BIT(msg); + if (len < 1 || len > 256*1024) + fatal("Authentication reply message too long: %d\n", len); + + /* Read the packet itself. */ + buffer_clear(&auth->identities); + while (len > 0) + { + l = len; + if (l > sizeof(msg)) + l = sizeof(msg); + l = read(auth->fd, msg, l); + if (l <= 0) + fatal("Incomplete authentication reply."); + buffer_append(&auth->identities, (char *)msg, l); + len -= l; + } + + /* Get message type, and verify that we got a proper answer. */ + buffer_get(&auth->identities, (char *)msg, 1); + if (msg[0] != SSH_AGENT_RSA_IDENTITIES_ANSWER) + fatal("Bad authentication reply message type: %d", msg[0]); + + /* Get the number of entries in the response and check it for sanity. */ + auth->howmany = buffer_get_int(&auth->identities); + if (auth->howmany > 1024) + fatal("Too many identities in authentication reply: %d\n", auth->howmany); + + /* Return the first entry (if any). */ + return ssh_get_next_identity(auth, bitsp, e, n, comment); +} + +/* Returns the next authentication identity for the agent. Other functions + can be called between this and ssh_get_first_identity or two calls of this + function. This returns 0 if there are no more identities. The caller + must free comment after a successful return. */ + +int +ssh_get_next_identity(AuthenticationConnection *auth, + int *bitsp, BIGNUM *e, BIGNUM *n, char **comment) +{ + /* Return failure if no more entries. */ + if (auth->howmany <= 0) + return 0; + + /* Get the next entry from the packet. These will abort with a fatal + error if the packet is too short or contains corrupt data. */ + *bitsp = buffer_get_int(&auth->identities); + buffer_get_bignum(&auth->identities, e); + buffer_get_bignum(&auth->identities, n); + *comment = buffer_get_string(&auth->identities, NULL); + + /* Decrement the number of remaining entries. */ + auth->howmany--; + + return 1; +} + +/* Generates a random challenge, sends it to the agent, and waits for response + from the agent. Returns true (non-zero) if the agent gave the correct + answer, zero otherwise. Response type selects the style of response + desired, with 0 corresponding to protocol version 1.0 (no longer supported) + and 1 corresponding to protocol version 1.1. */ + +int +ssh_decrypt_challenge(AuthenticationConnection *auth, + int bits, BIGNUM *e, BIGNUM *n, BIGNUM *challenge, + unsigned char session_id[16], + unsigned int response_type, + unsigned char response[16]) +{ + Buffer buffer; + unsigned char buf[8192]; + int len, l, i; + + /* Response type 0 is no longer supported. */ + if (response_type == 0) + fatal("Compatibility with ssh protocol version 1.0 no longer supported."); + + /* Format a message to the agent. */ + buf[0] = SSH_AGENTC_RSA_CHALLENGE; + buffer_init(&buffer); + buffer_append(&buffer, (char *)buf, 1); + buffer_put_int(&buffer, bits); + buffer_put_bignum(&buffer, e); + buffer_put_bignum(&buffer, n); + buffer_put_bignum(&buffer, challenge); + buffer_append(&buffer, (char *)session_id, 16); + buffer_put_int(&buffer, response_type); + + /* Get the length of the message, and format it in the buffer. */ + len = buffer_len(&buffer); + PUT_32BIT(buf, len); + + /* Send the length and then the packet to the agent. */ + if (write(auth->fd, buf, 4) != 4 || + write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != + buffer_len(&buffer)) + { + error("Error writing to authentication socket."); + error_cleanup: + buffer_free(&buffer); + return 0; + } + + /* Wait for response from the agent. First read the length of the + response packet. */ + len = 4; + while (len > 0) + { + l = read(auth->fd, buf + 4 - len, len); + if (l <= 0) + { + error("Error reading response length from authentication socket."); + goto error_cleanup; + } + len -= l; + } + + /* Extract the length, and check it for sanity. */ + len = GET_32BIT(buf); + if (len > 256*1024) + fatal("Authentication response too long: %d", len); + + /* Read the rest of the response in tothe buffer. */ + buffer_clear(&buffer); + while (len > 0) + { + l = len; + if (l > sizeof(buf)) + l = sizeof(buf); + l = read(auth->fd, buf, l); + if (l <= 0) + { + error("Error reading response from authentication socket."); + goto error_cleanup; + } + buffer_append(&buffer, (char *)buf, l); + len -= l; + } + + /* Get the type of the packet. */ + buffer_get(&buffer, (char *)buf, 1); + + /* Check for agent failure message. */ + if (buf[0] == SSH_AGENT_FAILURE) + { + log("Agent admitted failure to authenticate using the key."); + goto error_cleanup; + } + + /* Now it must be an authentication response packet. */ + if (buf[0] != SSH_AGENT_RSA_RESPONSE) + fatal("Bad authentication response: %d", buf[0]); + + /* Get the response from the packet. This will abort with a fatal error + if the packet is corrupt. */ + for (i = 0; i < 16; i++) + response[i] = buffer_get_char(&buffer); + + /* The buffer containing the packet is no longer needed. */ + buffer_free(&buffer); + + /* Correct answer. */ + return 1; +} + +/* Adds an identity to the authentication server. This call is not meant to + be used by normal applications. */ + +int ssh_add_identity(AuthenticationConnection *auth, + RSA *key, const char *comment) +{ + Buffer buffer; + unsigned char buf[8192]; + int len, l, type; + + /* Format a message to the agent. */ + buffer_init(&buffer); + buffer_put_char(&buffer, SSH_AGENTC_ADD_RSA_IDENTITY); + buffer_put_int(&buffer, BN_num_bits(key->n)); + buffer_put_bignum(&buffer, key->n); + buffer_put_bignum(&buffer, key->e); + buffer_put_bignum(&buffer, key->d); + /* To keep within the protocol: p < q for ssh. in SSL p > q */ + buffer_put_bignum(&buffer, key->iqmp); /* ssh key->u */ + buffer_put_bignum(&buffer, key->q); /* ssh key->p, SSL key->q */ + buffer_put_bignum(&buffer, key->p); /* ssh key->q, SSL key->p */ + buffer_put_string(&buffer, comment, strlen(comment)); + + /* Get the length of the message, and format it in the buffer. */ + len = buffer_len(&buffer); + PUT_32BIT(buf, len); + + /* Send the length and then the packet to the agent. */ + if (write(auth->fd, buf, 4) != 4 || + write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != + buffer_len(&buffer)) + { + error("Error writing to authentication socket."); + error_cleanup: + buffer_free(&buffer); + return 0; + } + + /* Wait for response from the agent. First read the length of the + response packet. */ + len = 4; + while (len > 0) + { + l = read(auth->fd, buf + 4 - len, len); + if (l <= 0) + { + error("Error reading response length from authentication socket."); + goto error_cleanup; + } + len -= l; + } + + /* Extract the length, and check it for sanity. */ + len = GET_32BIT(buf); + if (len > 256*1024) + fatal("Add identity response too long: %d", len); + + /* Read the rest of the response in tothe buffer. */ + buffer_clear(&buffer); + while (len > 0) + { + l = len; + if (l > sizeof(buf)) + l = sizeof(buf); + l = read(auth->fd, buf, l); + if (l <= 0) + { + error("Error reading response from authentication socket."); + goto error_cleanup; + } + buffer_append(&buffer, (char *)buf, l); + len -= l; + } + + /* Get the type of the packet. */ + type = buffer_get_char(&buffer); + switch (type) + { + case SSH_AGENT_FAILURE: + buffer_free(&buffer); + return 0; + case SSH_AGENT_SUCCESS: + buffer_free(&buffer); + return 1; + default: + fatal("Bad response to add identity from authentication agent: %d", + type); + } + /*NOTREACHED*/ + return 0; +} + +/* Removes an identity from the authentication server. This call is not meant + to be used by normal applications. */ + +int ssh_remove_identity(AuthenticationConnection *auth, RSA *key) +{ + Buffer buffer; + unsigned char buf[8192]; + int len, l, type; + + /* Format a message to the agent. */ + buffer_init(&buffer); + buffer_put_char(&buffer, SSH_AGENTC_REMOVE_RSA_IDENTITY); + buffer_put_int(&buffer, BN_num_bits(key->n)); + buffer_put_bignum(&buffer, key->e); + buffer_put_bignum(&buffer, key->n); + + /* Get the length of the message, and format it in the buffer. */ + len = buffer_len(&buffer); + PUT_32BIT(buf, len); + + /* Send the length and then the packet to the agent. */ + if (write(auth->fd, buf, 4) != 4 || + write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != + buffer_len(&buffer)) + { + error("Error writing to authentication socket."); + error_cleanup: + buffer_free(&buffer); + return 0; + } + + /* Wait for response from the agent. First read the length of the + response packet. */ + len = 4; + while (len > 0) + { + l = read(auth->fd, buf + 4 - len, len); + if (l <= 0) + { + error("Error reading response length from authentication socket."); + goto error_cleanup; + } + len -= l; + } + + /* Extract the length, and check it for sanity. */ + len = GET_32BIT(buf); + if (len > 256*1024) + fatal("Remove identity response too long: %d", len); + + /* Read the rest of the response in tothe buffer. */ + buffer_clear(&buffer); + while (len > 0) + { + l = len; + if (l > sizeof(buf)) + l = sizeof(buf); + l = read(auth->fd, buf, l); + if (l <= 0) + { + error("Error reading response from authentication socket."); + goto error_cleanup; + } + buffer_append(&buffer, (char *)buf, l); + len -= l; + } + + /* Get the type of the packet. */ + type = buffer_get_char(&buffer); + switch (type) + { + case SSH_AGENT_FAILURE: + buffer_free(&buffer); + return 0; + case SSH_AGENT_SUCCESS: + buffer_free(&buffer); + return 1; + default: + fatal("Bad response to remove identity from authentication agent: %d", + type); + } + /*NOTREACHED*/ + return 0; +} + +/* Removes all identities from the agent. This call is not meant + to be used by normal applications. */ + +int ssh_remove_all_identities(AuthenticationConnection *auth) +{ + Buffer buffer; + unsigned char buf[8192]; + int len, l, type; + + /* Get the length of the message, and format it in the buffer. */ + PUT_32BIT(buf, 1); + buf[4] = SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES; + + /* Send the length and then the packet to the agent. */ + if (write(auth->fd, buf, 5) != 5) + { + error("Error writing to authentication socket."); + return 0; + } + + /* Wait for response from the agent. First read the length of the + response packet. */ + len = 4; + while (len > 0) + { + l = read(auth->fd, buf + 4 - len, len); + if (l <= 0) + { + error("Error reading response length from authentication socket."); + return 0; + } + len -= l; + } + + /* Extract the length, and check it for sanity. */ + len = GET_32BIT(buf); + if (len > 256*1024) + fatal("Remove identity response too long: %d", len); + + /* Read the rest of the response into the buffer. */ + buffer_init(&buffer); + while (len > 0) + { + l = len; + if (l > sizeof(buf)) + l = sizeof(buf); + l = read(auth->fd, buf, l); + if (l <= 0) + { + error("Error reading response from authentication socket."); + buffer_free(&buffer); + return 0; + } + buffer_append(&buffer, (char *)buf, l); + len -= l; + } + + /* Get the type of the packet. */ + type = buffer_get_char(&buffer); + switch (type) + { + case SSH_AGENT_FAILURE: + buffer_free(&buffer); + return 0; + case SSH_AGENT_SUCCESS: + buffer_free(&buffer); + return 1; + default: + fatal("Bad response to remove identity from authentication agent: %d", + type); + } + /*NOTREACHED*/ + return 0; +} diff --git a/authfd.h b/authfd.h new file mode 100644 index 00000000..459a2020 --- /dev/null +++ b/authfd.h @@ -0,0 +1,102 @@ +/* + +authfd.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Mar 29 01:17:41 1995 ylo + +Functions to interface with the SSH_AUTHENTICATION_FD socket. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef AUTHFD_H +#define AUTHFD_H + +#include "buffer.h" + +/* Messages for the authentication agent connection. */ +#define SSH_AGENTC_REQUEST_RSA_IDENTITIES 1 +#define SSH_AGENT_RSA_IDENTITIES_ANSWER 2 +#define SSH_AGENTC_RSA_CHALLENGE 3 +#define SSH_AGENT_RSA_RESPONSE 4 +#define SSH_AGENT_FAILURE 5 +#define SSH_AGENT_SUCCESS 6 +#define SSH_AGENTC_ADD_RSA_IDENTITY 7 +#define SSH_AGENTC_REMOVE_RSA_IDENTITY 8 +#define SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES 9 + +typedef struct +{ + int fd; + Buffer packet; + Buffer identities; + int howmany; +} AuthenticationConnection; + +/* Returns the number of the authentication fd, or -1 if there is none. */ +int ssh_get_authentication_socket(); + +/* This should be called for any descriptor returned by + ssh_get_authentication_socket(). Depending on the way the descriptor was + obtained, this may close the descriptor. */ +void ssh_close_authentication_socket(int authfd); + +/* Opens and connects a private socket for communication with the + authentication agent. Returns NULL if an error occurred and the + connection could not be opened. The connection should be closed by + the caller by calling ssh_close_authentication_connection(). */ +AuthenticationConnection *ssh_get_authentication_connection(); + +/* Closes the connection to the authentication agent and frees any associated + memory. */ +void ssh_close_authentication_connection(AuthenticationConnection *ac); + +/* Returns the first authentication identity held by the agent. + Returns true if an identity is available, 0 otherwise. + The caller must initialize the integers before the call, and free the + comment after a successful call (before calling ssh_get_next_identity). */ +int ssh_get_first_identity(AuthenticationConnection *connection, + int *bitsp, BIGNUM *e, BIGNUM *n, char **comment); + +/* Returns the next authentication identity for the agent. Other functions + can be called between this and ssh_get_first_identity or two calls of this + function. This returns 0 if there are no more identities. The caller + must free comment after a successful return. */ +int ssh_get_next_identity(AuthenticationConnection *connection, + int *bitsp, BIGNUM *e, BIGNUM *n, char **comment); + +/* Requests the agent to decrypt the given challenge. Returns true if + the agent claims it was able to decrypt it. */ +int ssh_decrypt_challenge(AuthenticationConnection *auth, + int bits, BIGNUM *e, BIGNUM *n, BIGNUM *challenge, + unsigned char session_id[16], + unsigned int response_type, + unsigned char response[16]); + +/* Adds an identity to the authentication server. This call is not meant to + be used by normal applications. This returns true if the identity + was successfully added. */ +int ssh_add_identity(AuthenticationConnection *connection, + RSA *key, const char *comment); + +/* Removes the identity from the authentication server. This call is + not meant to be used by normal applications. This returns true if the + identity was successfully added. */ +int ssh_remove_identity(AuthenticationConnection *connection, + RSA *key); + +/* Removes all identities from the authentication agent. This call is not + meant to be used by normal applications. This returns true if the + operation was successful. */ +int ssh_remove_all_identities(AuthenticationConnection *connection); + +/* Closes the connection to the authentication agent. */ +void ssh_close_authentication(AuthenticationConnection *connection); + +#endif /* AUTHFD_H */ diff --git a/authfile.c b/authfile.c new file mode 100644 index 00000000..90c470d5 --- /dev/null +++ b/authfile.c @@ -0,0 +1,350 @@ +/* + +authfile.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Mon Mar 27 03:52:05 1995 ylo + +This file contains functions for reading and writing identity files, and +for reading the passphrase from the user. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include +#include "xmalloc.h" +#include "buffer.h" +#include "bufaux.h" +#include "cipher.h" +#include "ssh.h" + +/* Version identification string for identity files. */ +#define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n" + +/* Saves the authentication (private) key in a file, encrypting it with + passphrase. The identification of the file (lowest 64 bits of n) + will precede the key to provide identification of the key without + needing a passphrase. */ + +int +save_private_key(const char *filename, const char *passphrase, + RSA *key, const char *comment) +{ + Buffer buffer, encrypted; + char buf[100], *cp; + int f, i; + CipherContext cipher; + int cipher_type; + u_int32_t rand; + + /* If the passphrase is empty, use SSH_CIPHER_NONE to ease converting to + another cipher; otherwise use SSH_AUTHFILE_CIPHER. */ + if (strcmp(passphrase, "") == 0) + cipher_type = SSH_CIPHER_NONE; + else + cipher_type = SSH_AUTHFILE_CIPHER; + + /* This buffer is used to built the secret part of the private key. */ + buffer_init(&buffer); + + /* Put checkbytes for checking passphrase validity. */ + rand = arc4random(); + buf[0] = rand & 0xff; + buf[1] = (rand >> 8) & 0xff; + buf[2] = buf[0]; + buf[3] = buf[1]; + buffer_append(&buffer, buf, 4); + + /* Store the private key (n and e will not be stored because they will + be stored in plain text, and storing them also in encrypted format + would just give known plaintext). */ + buffer_put_bignum(&buffer, key->d); + buffer_put_bignum(&buffer, key->iqmp); + buffer_put_bignum(&buffer, key->q); /* reverse from SSL p */ + buffer_put_bignum(&buffer, key->p); /* reverse from SSL q */ + + /* Pad the part to be encrypted until its size is a multiple of 8. */ + while (buffer_len(&buffer) % 8 != 0) + buffer_put_char(&buffer, 0); + + /* This buffer will be used to contain the data in the file. */ + buffer_init(&encrypted); + + /* First store keyfile id string. */ + cp = AUTHFILE_ID_STRING; + for (i = 0; cp[i]; i++) + buffer_put_char(&encrypted, cp[i]); + buffer_put_char(&encrypted, 0); + + /* Store cipher type. */ + buffer_put_char(&encrypted, cipher_type); + buffer_put_int(&encrypted, 0); /* For future extension */ + + /* Store public key. This will be in plain text. */ + buffer_put_int(&encrypted, BN_num_bits(key->n)); + buffer_put_bignum(&encrypted, key->n); + buffer_put_bignum(&encrypted, key->e); + buffer_put_string(&encrypted, comment, strlen(comment)); + + /* Allocate space for the private part of the key in the buffer. */ + buffer_append_space(&encrypted, &cp, buffer_len(&buffer)); + + cipher_set_key_string(&cipher, cipher_type, passphrase, 1); + cipher_encrypt(&cipher, (unsigned char *)cp, + (unsigned char *)buffer_ptr(&buffer), + buffer_len(&buffer)); + memset(&cipher, 0, sizeof(cipher)); + + /* Destroy temporary data. */ + memset(buf, 0, sizeof(buf)); + buffer_free(&buffer); + + /* Write to a file. */ + f = open(filename, O_WRONLY|O_CREAT|O_TRUNC, 0600); + if (f < 0) + return 0; + + if (write(f, buffer_ptr(&encrypted), buffer_len(&encrypted)) != + buffer_len(&encrypted)) + { + debug("Write to key file %.200s failed: %.100s", filename, + strerror(errno)); + buffer_free(&encrypted); + close(f); + remove(filename); + return 0; + } + close(f); + buffer_free(&encrypted); + return 1; +} + +/* Loads the public part of the key file. Returns 0 if an error + was encountered (the file does not exist or is not readable), and + non-zero otherwise. */ + +int +load_public_key(const char *filename, RSA *pub, + char **comment_return) +{ + int f, i; + off_t len; + Buffer buffer; + char *cp; + + /* Read data from the file into the buffer. */ + f = open(filename, O_RDONLY); + if (f < 0) + return 0; + + len = lseek(f, (off_t)0, SEEK_END); + lseek(f, (off_t)0, SEEK_SET); + + buffer_init(&buffer); + buffer_append_space(&buffer, &cp, len); + + if (read(f, cp, (size_t)len) != (size_t)len) + { + debug("Read from key file %.200s failed: %.100s", filename, + strerror(errno)); + buffer_free(&buffer); + close(f); + return 0; + } + close(f); + + /* Check that it is at least big enought to contain the ID string. */ + if (len < strlen(AUTHFILE_ID_STRING) + 1) + { + debug("Bad key file %.200s.", filename); + buffer_free(&buffer); + return 0; + } + + /* Make sure it begins with the id string. Consume the id string from + the buffer. */ + for (i = 0; i < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++) + if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i]) + { + debug("Bad key file %.200s.", filename); + buffer_free(&buffer); + return 0; + } + + /* Skip cipher type and reserved data. */ + (void)buffer_get_char(&buffer); /* cipher type */ + (void)buffer_get_int(&buffer); /* reserved */ + + /* Read the public key from the buffer. */ + buffer_get_int(&buffer); + pub->n = BN_new(); + buffer_get_bignum(&buffer, pub->n); + pub->e = BN_new(); + buffer_get_bignum(&buffer, pub->e); + if (comment_return) + *comment_return = buffer_get_string(&buffer, NULL); + /* The encrypted private part is not parsed by this function. */ + + buffer_free(&buffer); + + return 1; +} + +/* Loads the private key from the file. Returns 0 if an error is encountered + (file does not exist or is not readable, or passphrase is bad). + This initializes the private key. */ + +int +load_private_key(const char *filename, const char *passphrase, + RSA *prv, char **comment_return) +{ + int f, i, check1, check2, cipher_type; + off_t len; + Buffer buffer, decrypted; + char *cp; + CipherContext cipher; + BN_CTX *ctx; + BIGNUM *aux; + struct stat st; + + /* Read the file into the buffer. */ + f = open(filename, O_RDONLY); + if (f < 0) + return 0; + + /* We assume we are called under uid of the owner of the file */ + if (fstat(f, &st) < 0 || + (st.st_uid != 0 && st.st_uid != getuid()) || + (st.st_mode & 077) != 0) { + error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); + error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @"); + error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); + error("Bad ownership or mode(0%3.3o) for '%s'.", + st.st_mode & 0777, filename); + error("It is recommended that your private key files are NOT accessible by others."); + return 0; + } + + len = lseek(f, (off_t)0, SEEK_END); + lseek(f, (off_t)0, SEEK_SET); + + buffer_init(&buffer); + buffer_append_space(&buffer, &cp, len); + + if (read(f, cp, (size_t)len) != (size_t)len) + { + debug("Read from key file %.200s failed: %.100s", filename, + strerror(errno)); + buffer_free(&buffer); + close(f); + return 0; + } + close(f); + + /* Check that it is at least big enought to contain the ID string. */ + if (len < strlen(AUTHFILE_ID_STRING) + 1) + { + debug("Bad key file %.200s.", filename); + buffer_free(&buffer); + return 0; + } + + /* Make sure it begins with the id string. Consume the id string from + the buffer. */ + for (i = 0; i < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++) + if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i]) + { + debug("Bad key file %.200s.", filename); + buffer_free(&buffer); + return 0; + } + + /* Read cipher type. */ + cipher_type = buffer_get_char(&buffer); + (void)buffer_get_int(&buffer); /* Reserved data. */ + + /* Read the public key from the buffer. */ + buffer_get_int(&buffer); + prv->n = BN_new(); + buffer_get_bignum(&buffer, prv->n); + prv->e = BN_new(); + buffer_get_bignum(&buffer, prv->e); + if (comment_return) + *comment_return = buffer_get_string(&buffer, NULL); + else + xfree(buffer_get_string(&buffer, NULL)); + + /* Check that it is a supported cipher. */ + if (((cipher_mask() | SSH_CIPHER_NONE | SSH_AUTHFILE_CIPHER) & + (1 << cipher_type)) == 0) + { + debug("Unsupported cipher %.100s used in key file %.200s.", + cipher_name(cipher_type), filename); + buffer_free(&buffer); + goto fail; + } + + /* Initialize space for decrypted data. */ + buffer_init(&decrypted); + buffer_append_space(&decrypted, &cp, buffer_len(&buffer)); + + /* Rest of the buffer is encrypted. Decrypt it using the passphrase. */ + cipher_set_key_string(&cipher, cipher_type, passphrase, 0); + cipher_decrypt(&cipher, (unsigned char *)cp, + (unsigned char *)buffer_ptr(&buffer), + buffer_len(&buffer)); + + buffer_free(&buffer); + + check1 = buffer_get_char(&decrypted); + check2 = buffer_get_char(&decrypted); + if (check1 != buffer_get_char(&decrypted) || + check2 != buffer_get_char(&decrypted)) + { + if (strcmp(passphrase, "") != 0) + debug("Bad passphrase supplied for key file %.200s.", filename); + /* Bad passphrase. */ + buffer_free(&decrypted); + fail: + BN_clear_free(prv->n); + BN_clear_free(prv->e); + if (comment_return) + xfree(*comment_return); + return 0; + } + + /* Read the rest of the private key. */ + prv->d = BN_new(); + buffer_get_bignum(&decrypted, prv->d); + prv->iqmp = BN_new(); + buffer_get_bignum(&decrypted, prv->iqmp); /* u */ + /* in SSL and SSH p and q are exchanged */ + prv->q = BN_new(); + buffer_get_bignum(&decrypted, prv->q); /* p */ + prv->p = BN_new(); + buffer_get_bignum(&decrypted, prv->p); /* q */ + + ctx = BN_CTX_new(); + aux = BN_new(); + + BN_sub(aux, prv->q, BN_value_one()); + prv->dmq1 = BN_new(); + BN_mod(prv->dmq1, prv->d, aux, ctx); + + BN_sub(aux, prv->p, BN_value_one()); + prv->dmp1 = BN_new(); + BN_mod(prv->dmp1, prv->d, aux, ctx); + + BN_clear_free(aux); + BN_CTX_free(ctx); + + buffer_free(&decrypted); + + return 1; +} diff --git a/bufaux.c b/bufaux.c new file mode 100644 index 00000000..56e03464 --- /dev/null +++ b/bufaux.c @@ -0,0 +1,141 @@ +/* + +bufaux.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Mar 29 02:24:47 1995 ylo + +Auxiliary functions for storing and retrieving various data types to/from +Buffers. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include +#include "bufaux.h" +#include "xmalloc.h" +#include "getput.h" + +/* Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed + by (bits+7)/8 bytes of binary data, msb first. */ + +void +buffer_put_bignum(Buffer *buffer, BIGNUM *value) +{ + int bits = BN_num_bits(value); + int bin_size = (bits + 7) / 8; + char *buf = xmalloc(bin_size); + int oi; + char msg[2]; + + /* Get the value of in binary */ + oi = BN_bn2bin(value, buf); + assert(oi == bin_size); + + /* Store the number of bits in the buffer in two bytes, msb first. */ + PUT_16BIT(msg, bits); + buffer_append(buffer, msg, 2); + /* Store the binary data. */ + buffer_append(buffer, buf, oi); + /* Clear the temporary data. */ + memset(buf, 0, bin_size); + xfree(buf); +} + +/* Retrieves an BIGNUM from the buffer. */ + +int +buffer_get_bignum(Buffer *buffer, BIGNUM *value) +{ + int bits, bytes; + unsigned char buf[2], *bin; + + /* Get the number for bits. */ + buffer_get(buffer, (char *)buf, 2); + bits = GET_16BIT(buf); + /* Compute the number of binary bytes that follow. */ + bytes = (bits + 7) / 8; + bin = xmalloc(bytes); + buffer_get(buffer, bin, bytes); + BN_bin2bn(bin, bytes, value); + xfree(bin); + + return 2 + bytes; +} + +/* Returns an integer from the buffer (4 bytes, msb first). */ + +unsigned int buffer_get_int(Buffer *buffer) +{ + unsigned char buf[4]; + buffer_get(buffer, (char *)buf, 4); + return GET_32BIT(buf); +} + +/* Stores an integer in the buffer in 4 bytes, msb first. */ + +void buffer_put_int(Buffer *buffer, unsigned int value) +{ + char buf[4]; + PUT_32BIT(buf, value); + buffer_append(buffer, buf, 4); +} + +/* Returns an arbitrary binary string from the buffer. The string cannot + be longer than 256k. The returned value points to memory allocated + with xmalloc; it is the responsibility of the calling function to free + the data. If length_ptr is non-NULL, the length of the returned data + will be stored there. A null character will be automatically appended + to the returned string, and is not counted in length. */ + +char *buffer_get_string(Buffer *buffer, unsigned int *length_ptr) +{ + unsigned int len; + char *value; + /* Get the length. */ + len = buffer_get_int(buffer); + if (len > 256*1024) + fatal("Received packet with bad string length %d", len); + /* Allocate space for the string. Add one byte for a null character. */ + value = xmalloc(len + 1); + /* Get the string. */ + buffer_get(buffer, value, len); + /* Append a null character to make processing easier. */ + value[len] = 0; + /* Optionally return the length of the string. */ + if (length_ptr) + *length_ptr = len; + return value; +} + +/* Stores and arbitrary binary string in the buffer. */ + +void buffer_put_string(Buffer *buffer, const void *buf, unsigned int len) +{ + buffer_put_int(buffer, len); + buffer_append(buffer, buf, len); +} + +/* Returns a character from the buffer (0 - 255). */ + +int buffer_get_char(Buffer *buffer) +{ + char ch; + buffer_get(buffer, &ch, 1); + return (unsigned char)ch; +} + +/* Stores a character in the buffer. */ + +void buffer_put_char(Buffer *buffer, int value) +{ + char ch = value; + buffer_append(buffer, &ch, 1); +} diff --git a/bufaux.h b/bufaux.h new file mode 100644 index 00000000..17cd871a --- /dev/null +++ b/bufaux.h @@ -0,0 +1,51 @@ +/* + +bufaux.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Mar 29 02:18:23 1995 ylo + +*/ + +/* RCSID("$Id$"); */ + +#ifndef BUFAUX_H +#define BUFAUX_H + +#include "buffer.h" + +/* Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed + by (bits+7)/8 bytes of binary data, msb first. */ +void buffer_put_bignum(Buffer *buffer, BIGNUM *value); + +/* Retrieves an BIGNUM from the buffer. */ +int buffer_get_bignum(Buffer *buffer, BIGNUM *value); + +/* Returns an integer from the buffer (4 bytes, msb first). */ +unsigned int buffer_get_int(Buffer *buffer); + +/* Stores an integer in the buffer in 4 bytes, msb first. */ +void buffer_put_int(Buffer *buffer, unsigned int value); + +/* Returns a character from the buffer (0 - 255). */ +int buffer_get_char(Buffer *buffer); + +/* Stores a character in the buffer. */ +void buffer_put_char(Buffer *buffer, int value); + +/* Returns an arbitrary binary string from the buffer. The string cannot + be longer than 256k. The returned value points to memory allocated + with xmalloc; it is the responsibility of the calling function to free + the data. If length_ptr is non-NULL, the length of the returned data + will be stored there. A null character will be automatically appended + to the returned string, and is not counted in length. */ +char *buffer_get_string(Buffer *buffer, unsigned int *length_ptr); + +/* Stores and arbitrary binary string in the buffer. */ +void buffer_put_string(Buffer *buffer, const void *buf, unsigned int len); + +#endif /* BUFAUX_H */ diff --git a/buffer.c b/buffer.c new file mode 100644 index 00000000..cf5d9e1f --- /dev/null +++ b/buffer.c @@ -0,0 +1,150 @@ +/* + +buffer.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Mar 18 04:15:33 1995 ylo + +Functions for manipulating fifo buffers (that can grow if needed). + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "xmalloc.h" +#include "buffer.h" +#include "ssh.h" + +/* Initializes the buffer structure. */ + +void buffer_init(Buffer *buffer) +{ + buffer->alloc = 4096; + buffer->buf = xmalloc(buffer->alloc); + buffer->offset = 0; + buffer->end = 0; +} + +/* Frees any memory used for the buffer. */ + +void buffer_free(Buffer *buffer) +{ + memset(buffer->buf, 0, buffer->alloc); + xfree(buffer->buf); +} + +/* Clears any data from the buffer, making it empty. This does not actually + zero the memory. */ + +void buffer_clear(Buffer *buffer) +{ + buffer->offset = 0; + buffer->end = 0; +} + +/* Appends data to the buffer, expanding it if necessary. */ + +void buffer_append(Buffer *buffer, const char *data, unsigned int len) +{ + char *cp; + buffer_append_space(buffer, &cp, len); + memcpy(cp, data, len); +} + +/* Appends space to the buffer, expanding the buffer if necessary. + This does not actually copy the data into the buffer, but instead + returns a pointer to the allocated region. */ + +void buffer_append_space(Buffer *buffer, char **datap, unsigned int len) +{ + /* If the buffer is empty, start using it from the beginning. */ + if (buffer->offset == buffer->end) + { + buffer->offset = 0; + buffer->end = 0; + } + + restart: + /* If there is enough space to store all data, store it now. */ + if (buffer->end + len < buffer->alloc) + { + *datap = buffer->buf + buffer->end; + buffer->end += len; + return; + } + + /* If the buffer is quite empty, but all data is at the end, move the + data to the beginning and retry. */ + if (buffer->offset > buffer->alloc / 2) + { + memmove(buffer->buf, buffer->buf + buffer->offset, + buffer->end - buffer->offset); + buffer->end -= buffer->offset; + buffer->offset = 0; + goto restart; + } + + /* Increase the size of the buffer and retry. */ + buffer->alloc += len + 32768; + buffer->buf = xrealloc(buffer->buf, buffer->alloc); + goto restart; +} + +/* Returns the number of bytes of data in the buffer. */ + +unsigned int buffer_len(Buffer *buffer) +{ + return buffer->end - buffer->offset; +} + +/* Gets data from the beginning of the buffer. */ + +void buffer_get(Buffer *buffer, char *buf, unsigned int len) +{ + if (len > buffer->end - buffer->offset) + fatal("buffer_get trying to get more bytes than in buffer"); + memcpy(buf, buffer->buf + buffer->offset, len); + buffer->offset += len; +} + +/* Consumes the given number of bytes from the beginning of the buffer. */ + +void buffer_consume(Buffer *buffer, unsigned int bytes) +{ + if (bytes > buffer->end - buffer->offset) + fatal("buffer_get trying to get more bytes than in buffer"); + buffer->offset += bytes; +} + +/* Consumes the given number of bytes from the end of the buffer. */ + +void buffer_consume_end(Buffer *buffer, unsigned int bytes) +{ + if (bytes > buffer->end - buffer->offset) + fatal("buffer_get trying to get more bytes than in buffer"); + buffer->end -= bytes; +} + +/* Returns a pointer to the first used byte in the buffer. */ + +char *buffer_ptr(Buffer *buffer) +{ + return buffer->buf + buffer->offset; +} + +/* Dumps the contents of the buffer to stderr. */ + +void buffer_dump(Buffer *buffer) +{ + int i; + unsigned char *ucp = (unsigned char *)buffer->buf; + + for (i = buffer->offset; i < buffer->end; i++) + fprintf(stderr, " %02x", ucp[i]); + fprintf(stderr, "\n"); +} diff --git a/buffer.h b/buffer.h new file mode 100644 index 00000000..681ad4ef --- /dev/null +++ b/buffer.h @@ -0,0 +1,66 @@ +/* + +buffer.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Mar 18 04:12:25 1995 ylo + +Code for manipulating FIFO buffers. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef BUFFER_H +#define BUFFER_H + +typedef struct +{ + char *buf; /* Buffer for data. */ + unsigned int alloc; /* Number of bytes allocated for data. */ + unsigned int offset; /* Offset of first byte containing data. */ + unsigned int end; /* Offset of last byte containing data. */ +} Buffer; + +/* Initializes the buffer structure. */ +void buffer_init(Buffer *buffer); + +/* Frees any memory used for the buffer. */ +void buffer_free(Buffer *buffer); + +/* Clears any data from the buffer, making it empty. This does not actually + zero the memory. */ +void buffer_clear(Buffer *buffer); + +/* Appends data to the buffer, expanding it if necessary. */ +void buffer_append(Buffer *buffer, const char *data, unsigned int len); + +/* Appends space to the buffer, expanding the buffer if necessary. + This does not actually copy the data into the buffer, but instead + returns a pointer to the allocated region. */ +void buffer_append_space(Buffer *buffer, char **datap, unsigned int len); + +/* Returns the number of bytes of data in the buffer. */ +unsigned int buffer_len(Buffer *buffer); + +/* Gets data from the beginning of the buffer. */ +void buffer_get(Buffer *buffer, char *buf, unsigned int len); + +/* Consumes the given number of bytes from the beginning of the buffer. */ +void buffer_consume(Buffer *buffer, unsigned int bytes); + +/* Consumes the given number of bytes from the end of the buffer. */ +void buffer_consume_end(Buffer *buffer, unsigned int bytes); + +/* Returns a pointer to the first used byte in the buffer. */ +char *buffer_ptr(Buffer *buffer); + +/* Dumps the contents of the buffer to stderr in hex. This intended for + debugging purposes only. */ +void buffer_dump(Buffer *buffer); + +#endif /* BUFFER_H */ diff --git a/canohost.c b/canohost.c new file mode 100644 index 00000000..01ba7112 --- /dev/null +++ b/canohost.c @@ -0,0 +1,234 @@ +/* + +canohost.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sun Jul 2 17:52:22 1995 ylo + +Functions for returning the canonical host name of the remote site. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "packet.h" +#include "xmalloc.h" +#include "ssh.h" + +/* Return the canonical name of the host at the other end of the socket. + The caller should free the returned string with xfree. */ + +char *get_remote_hostname(int socket) +{ + struct sockaddr_in from; + int fromlen, i; + struct hostent *hp; + char name[MAXHOSTNAMELEN]; + + /* Get IP address of client. */ + fromlen = sizeof(from); + memset(&from, 0, sizeof(from)); + if (getpeername(socket, (struct sockaddr *)&from, &fromlen) < 0) + { + error("getpeername failed: %.100s", strerror(errno)); + strlcpy(name, "UNKNOWN", sizeof name); + goto check_ip_options; + } + + /* Map the IP address to a host name. */ + hp = gethostbyaddr((char *)&from.sin_addr, sizeof(struct in_addr), + from.sin_family); + if (hp) + { + /* Got host name, find canonic host name. */ + if (strchr(hp->h_name, '.') != 0) + strlcpy(name, hp->h_name, sizeof(name)); + else if (hp->h_aliases != 0 + && hp->h_aliases[0] != 0 + && strchr(hp->h_aliases[0], '.') != 0) + strlcpy(name, hp->h_aliases[0], sizeof(name)); + else + strlcpy(name, hp->h_name, sizeof(name)); + + /* Convert it to all lowercase (which is expected by the rest of this + software). */ + for (i = 0; name[i]; i++) + if (isupper(name[i])) + name[i] = tolower(name[i]); + + /* Map it back to an IP address and check that the given address actually + is an address of this host. This is necessary because anyone with + access to a name server can define arbitrary names for an IP address. + Mapping from name to IP address can be trusted better (but can still + be fooled if the intruder has access to the name server of the + domain). */ + hp = gethostbyname(name); + if (!hp) + { + log("reverse mapping checking gethostbyname for %.700s failed - POSSIBLE BREAKIN ATTEMPT!", name); + strlcpy(name, inet_ntoa(from.sin_addr), sizeof name); + goto check_ip_options; + } + /* Look for the address from the list of addresses. */ + for (i = 0; hp->h_addr_list[i]; i++) + if (memcmp(hp->h_addr_list[i], &from.sin_addr, sizeof(from.sin_addr)) + == 0) + break; + /* If we reached the end of the list, the address was not there. */ + if (!hp->h_addr_list[i]) + { + /* Address not found for the host name. */ + log("Address %.100s maps to %.600s, but this does not map back to the address - POSSIBLE BREAKIN ATTEMPT!", + inet_ntoa(from.sin_addr), name); + strlcpy(name, inet_ntoa(from.sin_addr), sizeof name); + goto check_ip_options; + } + /* Address was found for the host name. We accept the host name. */ + } + else + { + /* Host name not found. Use ascii representation of the address. */ + strlcpy(name, inet_ntoa(from.sin_addr), sizeof name); + log("Could not reverse map address %.100s.", name); + } + + check_ip_options: + + /* If IP options are supported, make sure there are none (log and clear + them if any are found). Basically we are worried about source routing; + it can be used to pretend you are somebody (ip-address) you are not. + That itself may be "almost acceptable" under certain circumstances, + but rhosts autentication is useless if source routing is accepted. + Notice also that if we just dropped source routing here, the other + side could use IP spoofing to do rest of the interaction and could still + bypass security. So we exit here if we detect any IP options. */ + { + unsigned char options[200], *ucp; + char text[1024], *cp; + int option_size, ipproto; + struct protoent *ip; + + if ((ip = getprotobyname("ip")) != NULL) + ipproto = ip->p_proto; + else + ipproto = IPPROTO_IP; + option_size = sizeof(options); + if (getsockopt(0, ipproto, IP_OPTIONS, (char *)options, + &option_size) >= 0 && option_size != 0) + { + cp = text; + /* Note: "text" buffer must be at least 3x as big as options. */ + for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3) + sprintf(cp, " %2.2x", *ucp); + log("Connection from %.100s with IP options:%.800s", + inet_ntoa(from.sin_addr), text); + packet_disconnect("Connection from %.100s with IP options:%.800s", + inet_ntoa(from.sin_addr), text); + } + } + + return xstrdup(name); +} + +static char *canonical_host_name = NULL; +static char *canonical_host_ip = NULL; + +/* Return the canonical name of the host in the other side of the current + connection. The host name is cached, so it is efficient to call this + several times. */ + +const char *get_canonical_hostname() +{ + /* Check if we have previously retrieved this same name. */ + if (canonical_host_name != NULL) + return canonical_host_name; + + /* Get the real hostname if socket; otherwise return UNKNOWN. */ + if (packet_get_connection_in() == packet_get_connection_out()) + canonical_host_name = get_remote_hostname(packet_get_connection_in()); + else + canonical_host_name = xstrdup("UNKNOWN"); + + return canonical_host_name; +} + +/* Returns the IP-address of the remote host as a string. The returned + string need not be freed. */ + +const char *get_remote_ipaddr() +{ + struct sockaddr_in from; + int fromlen, socket; + + /* Check if we have previously retrieved this same name. */ + if (canonical_host_ip != NULL) + return canonical_host_ip; + + /* If not a socket, return UNKNOWN. */ + if (packet_get_connection_in() != packet_get_connection_out()) + { + canonical_host_ip = xstrdup("UNKNOWN"); + return canonical_host_ip; + } + + /* Get client socket. */ + socket = packet_get_connection_in(); + + /* Get IP address of client. */ + fromlen = sizeof(from); + memset(&from, 0, sizeof(from)); + if (getpeername(socket, (struct sockaddr *)&from, &fromlen) < 0) + { + error("getpeername failed: %.100s", strerror(errno)); + return NULL; + } + + /* Get the IP address in ascii. */ + canonical_host_ip = xstrdup(inet_ntoa(from.sin_addr)); + + /* Return ip address string. */ + return canonical_host_ip; +} + +/* Returns the port of the peer of the socket. */ + +int get_peer_port(int sock) +{ + struct sockaddr_in from; + int fromlen; + + /* Get IP address of client. */ + fromlen = sizeof(from); + memset(&from, 0, sizeof(from)); + if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) + { + error("getpeername failed: %.100s", strerror(errno)); + return 0; + } + + /* Return port number. */ + return ntohs(from.sin_port); +} + +/* Returns the port number of the remote host. */ + +int get_remote_port() +{ + int socket; + + /* If the connection is not a socket, return 65535. This is intentionally + chosen to be an unprivileged port number. */ + if (packet_get_connection_in() != packet_get_connection_out()) + return 65535; + + /* Get client socket. */ + socket = packet_get_connection_in(); + + /* Get and return the peer port number. */ + return get_peer_port(socket); +} diff --git a/channels.c b/channels.c new file mode 100644 index 00000000..7766bddf --- /dev/null +++ b/channels.c @@ -0,0 +1,1500 @@ +/* + +channels.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Fri Mar 24 16:35:24 1995 ylo + +This file contains functions for generic socket connection forwarding. +There is also code for initiating connection forwarding for X11 connections, +arbitrary tcp/ip connections, and the authentication agent connection. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include "packet.h" +#include "xmalloc.h" +#include "buffer.h" +#include "authfd.h" +#include "uidswap.h" +#include "servconf.h" + +#include "channels.h" +#include "nchan.h" +#include "compat.h" + +/* Maximum number of fake X11 displays to try. */ +#define MAX_DISPLAYS 1000 + +/* Max len of agent socket */ +#define MAX_SOCKET_NAME 100 + +/* Pointer to an array containing all allocated channels. The array is + dynamically extended as needed. */ +static Channel *channels = NULL; + +/* Size of the channel array. All slots of the array must always be + initialized (at least the type field); unused slots are marked with + type SSH_CHANNEL_FREE. */ +static int channels_alloc = 0; + +/* Maximum file descriptor value used in any of the channels. This is updated + in channel_allocate. */ +static int channel_max_fd_value = 0; + +/* Name and directory of socket for authentication agent forwarding. */ +static char *channel_forwarded_auth_socket_name = NULL; +static char *channel_forwarded_auth_socket_dir = NULL; + +/* Saved X11 authentication protocol name. */ +char *x11_saved_proto = NULL; + +/* Saved X11 authentication data. This is the real data. */ +char *x11_saved_data = NULL; +unsigned int x11_saved_data_len = 0; + +/* Fake X11 authentication data. This is what the server will be sending + us; we should replace any occurrences of this by the real data. */ +char *x11_fake_data = NULL; +unsigned int x11_fake_data_len; + +/* Data structure for storing which hosts are permitted for forward requests. + The local sides of any remote forwards are stored in this array to prevent + a corrupt remote server from accessing arbitrary TCP/IP ports on our + local network (which might be behind a firewall). */ +typedef struct +{ + char *host; /* Host name. */ + int port; /* Port number. */ +} ForwardPermission; + +/* List of all permitted host/port pairs to connect. */ +static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION]; +/* Number of permitted host/port pairs in the array. */ +static int num_permitted_opens = 0; +/* If this is true, all opens are permitted. This is the case on the + server on which we have to trust the client anyway, and the user could + do anything after logging in anyway. */ +static int all_opens_permitted = 0; + +/* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */ +static int have_hostname_in_open = 0; + +/* Sets specific protocol options. */ + +void channel_set_options(int hostname_in_open) +{ + have_hostname_in_open = hostname_in_open; +} + +/* Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually + called by the server, because the user could connect to any port anyway, + and the server has no way to know but to trust the client anyway. */ + +void channel_permit_all_opens() +{ + all_opens_permitted = 1; +} + +/* Allocate a new channel object and set its type and socket. + This will cause remote_name to be freed. */ + +int channel_allocate(int type, int sock, char *remote_name) +{ + int i, old_channels; + + /* Update the maximum file descriptor value. */ + if (sock > channel_max_fd_value) + channel_max_fd_value = sock; + + /* Do initial allocation if this is the first call. */ + if (channels_alloc == 0) + { + channels_alloc = 10; + channels = xmalloc(channels_alloc * sizeof(Channel)); + for (i = 0; i < channels_alloc; i++) + channels[i].type = SSH_CHANNEL_FREE; + + /* Kludge: arrange a call to channel_stop_listening if we terminate + with fatal(). */ + fatal_add_cleanup((void (*)(void *))channel_stop_listening, NULL); + } + + /* Try to find a free slot where to put the new channel. */ + for (i = 0; i < channels_alloc; i++) + if (channels[i].type == SSH_CHANNEL_FREE) + { + /* Found a free slot. Initialize the fields and return its number. */ + buffer_init(&channels[i].input); + buffer_init(&channels[i].output); + channels[i].self = i; + channels[i].type = type; + channels[i].x11 = 0; + channels[i].sock = sock; + channels[i].remote_id = -1; + channels[i].remote_name = remote_name; + chan_init_iostates(&channels[i]); + return i; + } + + /* There are no free slots. Must expand the array. */ + old_channels = channels_alloc; + channels_alloc += 10; + channels = xrealloc(channels, channels_alloc * sizeof(Channel)); + for (i = old_channels; i < channels_alloc; i++) + channels[i].type = SSH_CHANNEL_FREE; + + /* We know that the next one after the old maximum channel number is now + available. Initialize and return its number. */ + buffer_init(&channels[old_channels].input); + buffer_init(&channels[old_channels].output); + channels[old_channels].self = old_channels; + channels[old_channels].type = type; + channels[old_channels].x11 = 0; + channels[old_channels].sock = sock; + channels[old_channels].remote_id = -1; + channels[old_channels].remote_name = remote_name; + chan_init_iostates(&channels[old_channels]); + return old_channels; +} + +/* Free the channel and close its socket. */ + +void channel_free(int channel) +{ + assert(channel >= 0 && channel < channels_alloc && + channels[channel].type != SSH_CHANNEL_FREE); + if(compat13) + shutdown(channels[channel].sock, SHUT_RDWR); + close(channels[channel].sock); + buffer_free(&channels[channel].input); + buffer_free(&channels[channel].output); + channels[channel].type = SSH_CHANNEL_FREE; + if (channels[channel].remote_name) + { + xfree(channels[channel].remote_name); + channels[channel].remote_name = NULL; + } +} + +/* This is called just before select() to add any bits relevant to + channels in the select bitmasks. */ + +void channel_prepare_select(fd_set *readset, fd_set *writeset) +{ + int i; + Channel *ch; + unsigned char *ucp; + unsigned int proto_len, data_len; + + for (i = 0; i < channels_alloc; i++) + { + ch = &channels[i]; + redo: + switch (ch->type) + { + case SSH_CHANNEL_X11_LISTENER: + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_AUTH_SOCKET: + FD_SET(ch->sock, readset); + break; + + case SSH_CHANNEL_OPEN: + if(compat13){ + if (buffer_len(&ch->input) < 32768) + FD_SET(ch->sock, readset); + if (buffer_len(&ch->output) > 0) + FD_SET(ch->sock, writeset); + break; + } + /* test whether sockets are 'alive' for read/write */ + if (ch->istate == CHAN_INPUT_OPEN) + if (buffer_len(&ch->input) < 32768) + FD_SET(ch->sock, readset); + if (ch->ostate == CHAN_OUTPUT_OPEN || ch->ostate == CHAN_OUTPUT_WAIT_DRAIN){ + if (buffer_len(&ch->output) > 0){ + FD_SET(ch->sock, writeset); + }else if(ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) { + chan_obuf_empty(ch); + } + } + break; + + case SSH_CHANNEL_INPUT_DRAINING: + if (!compat13) + fatal("cannot happen: IN_DRAIN"); + if (buffer_len(&ch->input) == 0) + { + packet_start(SSH_MSG_CHANNEL_CLOSE); + packet_put_int(ch->remote_id); + packet_send(); + ch->type = SSH_CHANNEL_CLOSED; + debug("Closing channel %d after input drain.", i); + break; + } + break; + + case SSH_CHANNEL_OUTPUT_DRAINING: + if (!compat13) + fatal("cannot happen: OUT_DRAIN"); + if (buffer_len(&ch->output) == 0) + { + /* debug("Freeing channel %d after output drain.", i); */ + channel_free(i); + break; + } + FD_SET(ch->sock, writeset); + break; + + case SSH_CHANNEL_X11_OPEN: + /* This is a special state for X11 authentication spoofing. An + opened X11 connection (when authentication spoofing is being + done) remains in this state until the first packet has been + completely read. The authentication data in that packet is + then substituted by the real data if it matches the fake data, + and the channel is put into normal mode. */ + + /* Check if the fixed size part of the packet is in buffer. */ + if (buffer_len(&ch->output) < 12) + break; + + /* Parse the lengths of variable-length fields. */ + ucp = (unsigned char *)buffer_ptr(&ch->output); + if (ucp[0] == 0x42) + { /* Byte order MSB first. */ + proto_len = 256 * ucp[6] + ucp[7]; + data_len = 256 * ucp[8] + ucp[9]; + } + else + if (ucp[0] == 0x6c) + { /* Byte order LSB first. */ + proto_len = ucp[6] + 256 * ucp[7]; + data_len = ucp[8] + 256 * ucp[9]; + } + else + { + debug("Initial X11 packet contains bad byte order byte: 0x%x", + ucp[0]); + ch->type = SSH_CHANNEL_OPEN; + goto reject; + } + + /* Check if the whole packet is in buffer. */ + if (buffer_len(&ch->output) < + 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3)) + break; + + /* Check if authentication protocol matches. */ + if (proto_len != strlen(x11_saved_proto) || + memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) + { + debug("X11 connection uses different authentication protocol."); + ch->type = SSH_CHANNEL_OPEN; + goto reject; + } + + /* Check if authentication data matches our fake data. */ + if (data_len != x11_fake_data_len || + memcmp(ucp + 12 + ((proto_len + 3) & ~3), + x11_fake_data, x11_fake_data_len) != 0) + { + debug("X11 auth data does not match fake data."); + ch->type = SSH_CHANNEL_OPEN; + goto reject; + } + + /* Received authentication protocol and data match our fake data. + Substitute the fake data with real data. */ + assert(x11_fake_data_len == x11_saved_data_len); + memcpy(ucp + 12 + ((proto_len + 3) & ~3), + x11_saved_data, x11_saved_data_len); + + /* Start normal processing for the channel. */ + ch->type = SSH_CHANNEL_OPEN; + /* Enable X11 Problem FIX */ + ch->x11 = 1; + goto redo; + + reject: + /* We have received an X11 connection that has bad authentication + information. */ + log("X11 connection rejected because of wrong authentication.\r\n"); + buffer_clear(&ch->input); + buffer_clear(&ch->output); + if (compat13) { + close(ch->sock); + ch->sock = -1; + ch->type = SSH_CHANNEL_CLOSED; + packet_start(SSH_MSG_CHANNEL_CLOSE); + packet_put_int(ch->remote_id); + packet_send(); + }else{ + debug("X11 rejected %d 0x%x 0x%x", ch->self, ch->istate, ch->ostate); + chan_read_failed(ch); + chan_write_failed(ch); + debug("X11 rejected %d 0x%x 0x%x", ch->self, ch->istate, ch->ostate); + } + break; + + case SSH_CHANNEL_FREE: + default: + continue; + } + } +} + +/* After select, perform any appropriate operations for channels which + have events pending. */ + +void channel_after_select(fd_set *readset, fd_set *writeset) +{ + struct sockaddr addr; + int addrlen, newsock, i, newch, len; + Channel *ch; + char buf[16384], *remote_hostname; + + /* Loop over all channels... */ + for (i = 0; i < channels_alloc; i++) + { + ch = &channels[i]; + switch (ch->type) + { + case SSH_CHANNEL_X11_LISTENER: + /* This is our fake X11 server socket. */ + if (FD_ISSET(ch->sock, readset)) + { + debug("X11 connection requested."); + addrlen = sizeof(addr); + newsock = accept(ch->sock, &addr, &addrlen); + if (newsock < 0) + { + error("accept: %.100s", strerror(errno)); + break; + } + remote_hostname = get_remote_hostname(newsock); + snprintf(buf, sizeof buf, "X11 connection from %.200s port %d", + remote_hostname, get_peer_port(newsock)); + xfree(remote_hostname); + newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, + xstrdup(buf)); + packet_start(SSH_SMSG_X11_OPEN); + packet_put_int(newch); + if (have_hostname_in_open) + packet_put_string(buf, strlen(buf)); + packet_send(); + } + break; + + case SSH_CHANNEL_PORT_LISTENER: + /* This socket is listening for connections to a forwarded TCP/IP + port. */ + if (FD_ISSET(ch->sock, readset)) + { + debug("Connection to port %d forwarding to %.100s:%d requested.", + ch->listening_port, ch->path, ch->host_port); + addrlen = sizeof(addr); + newsock = accept(ch->sock, &addr, &addrlen); + if (newsock < 0) + { + error("accept: %.100s", strerror(errno)); + break; + } + remote_hostname = get_remote_hostname(newsock); + snprintf(buf, sizeof buf, "port %d, connection from %.200s port %d", + ch->listening_port, remote_hostname, + get_peer_port(newsock)); + xfree(remote_hostname); + newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, + xstrdup(buf)); + packet_start(SSH_MSG_PORT_OPEN); + packet_put_int(newch); + packet_put_string(ch->path, strlen(ch->path)); + packet_put_int(ch->host_port); + if (have_hostname_in_open) + packet_put_string(buf, strlen(buf)); + packet_send(); + } + break; + + case SSH_CHANNEL_AUTH_SOCKET: + /* This is the authentication agent socket listening for connections + from clients. */ + if (FD_ISSET(ch->sock, readset)) + { + int nchan; + len = sizeof(addr); + newsock = accept(ch->sock, &addr, &len); + if (newsock < 0) + { + error("accept from auth socket: %.100s", strerror(errno)); + break; + } + + nchan = channel_allocate(SSH_CHANNEL_OPENING, newsock, + xstrdup("accepted auth socket")); + packet_start(SSH_SMSG_AGENT_OPEN); + packet_put_int(nchan); + packet_send(); + } + break; + + case SSH_CHANNEL_OPEN: + /* This is an open two-way communication channel. It is not of + interest to us at this point what kind of data is being + transmitted. */ + + /* Read available incoming data and append it to buffer; + shutdown socket, if read or write failes */ + if (FD_ISSET(ch->sock, readset)) + { + len = read(ch->sock, buf, sizeof(buf)); + if (len <= 0) + { + if (compat13) { + buffer_consume(&ch->output, buffer_len(&ch->output)); + ch->type = SSH_CHANNEL_INPUT_DRAINING; + debug("Channel %d status set to input draining.", i); + }else{ + chan_read_failed(ch); + } + break; + } + buffer_append(&ch->input, buf, len); + } + /* Send buffered output data to the socket. */ + if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) + { + len = write(ch->sock, buffer_ptr(&ch->output), + buffer_len(&ch->output)); + if (len <= 0) + { + if (compat13) { + buffer_consume(&ch->output, buffer_len(&ch->output)); + debug("Channel %d status set to input draining.", i); + ch->type = SSH_CHANNEL_INPUT_DRAINING; + }else{ + chan_write_failed(ch); + } + break; + } + buffer_consume(&ch->output, len); + } + break; + + case SSH_CHANNEL_OUTPUT_DRAINING: + if (!compat13) + fatal("cannot happen: OUT_DRAIN"); + /* Send buffered output data to the socket. */ + if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) + { + len = write(ch->sock, buffer_ptr(&ch->output), + buffer_len(&ch->output)); + if (len <= 0) + buffer_consume(&ch->output, buffer_len(&ch->output)); + else + buffer_consume(&ch->output, len); + } + break; + + case SSH_CHANNEL_X11_OPEN: + case SSH_CHANNEL_FREE: + default: + continue; + } + } +} + +/* If there is data to send to the connection, send some of it now. */ + +void channel_output_poll() +{ + int len, i; + Channel *ch; + + for (i = 0; i < channels_alloc; i++) + { + ch = &channels[i]; + /* We are only interested in channels that can have buffered incoming + data. */ + if (ch->type != SSH_CHANNEL_OPEN && + ch->type != SSH_CHANNEL_INPUT_DRAINING) + continue; + + /* Get the amount of buffered data for this channel. */ + len = buffer_len(&ch->input); + if (len > 0) + { + /* Send some data for the other side over the secure connection. */ + if (packet_is_interactive()) + { + if (len > 1024) + len = 512; + } + else + { + if (len > 16384) + len = 16384; /* Keep the packets at reasonable size. */ + } + packet_start(SSH_MSG_CHANNEL_DATA); + packet_put_int(ch->remote_id); + packet_put_string(buffer_ptr(&ch->input), len); + packet_send(); + buffer_consume(&ch->input, len); + } + else if(ch->istate == CHAN_INPUT_WAIT_DRAIN) + { + if (compat13) + fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3"); + /* input-buffer is empty and read-socket shutdown: + tell peer, that we will not send more data: send IEOF */ + chan_ibuf_empty(ch); + } + } +} + +/* This is called when a packet of type CHANNEL_DATA has just been received. + The message type has already been consumed, but channel number and data + is still there. */ + +void channel_input_data(int payload_len) +{ + int channel; + char *data; + unsigned int data_len; + + /* Get the channel number and verify it. */ + channel = packet_get_int(); + if (channel < 0 || channel >= channels_alloc || + channels[channel].type == SSH_CHANNEL_FREE) + packet_disconnect("Received data for nonexistent channel %d.", channel); + + /* Ignore any data for non-open channels (might happen on close) */ + if (channels[channel].type != SSH_CHANNEL_OPEN && + channels[channel].type != SSH_CHANNEL_X11_OPEN) + return; + + /* Get the data. */ + data = packet_get_string(&data_len); + packet_integrity_check(payload_len, 4 + 4+data_len, SSH_MSG_CHANNEL_DATA); + buffer_append(&channels[channel].output, data, data_len); + xfree(data); +} + +/* Returns true if no channel has too much buffered data, and false if + one or more channel is overfull. */ + +int channel_not_very_much_buffered_data() +{ + unsigned int i; + Channel *ch; + + for (i = 0; i < channels_alloc; i++) + { + ch = &channels[i]; + switch (ch->type) + { + case SSH_CHANNEL_X11_LISTENER: + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_AUTH_SOCKET: + continue; + case SSH_CHANNEL_OPEN: + if (buffer_len(&ch->input) > 32768) + return 0; + if (buffer_len(&ch->output) > 32768) + return 0; + continue; + case SSH_CHANNEL_INPUT_DRAINING: + case SSH_CHANNEL_OUTPUT_DRAINING: + case SSH_CHANNEL_X11_OPEN: + case SSH_CHANNEL_FREE: + default: + continue; + } + } + return 1; +} + +/* This is called after receiving CHANNEL_CLOSE/IEOF. */ + +void channel_input_close() +{ + int channel; + + /* Get the channel number and verify it. */ + channel = packet_get_int(); + if (channel < 0 || channel >= channels_alloc || + channels[channel].type == SSH_CHANNEL_FREE) + packet_disconnect("Received data for nonexistent channel %d.", channel); + + if(!compat13){ + /* proto version 1.5 overloads CLOSE with IEOF */ + chan_rcvd_ieof(&channels[channel]); + return; + } + + /* Send a confirmation that we have closed the channel and no more data is + coming for it. */ + packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION); + packet_put_int(channels[channel].remote_id); + packet_send(); + + /* If the channel is in closed state, we have sent a close request, and + the other side will eventually respond with a confirmation. Thus, + we cannot free the channel here, because then there would be no-one to + receive the confirmation. The channel gets freed when the confirmation + arrives. */ + if (channels[channel].type != SSH_CHANNEL_CLOSED) + { + /* Not a closed channel - mark it as draining, which will cause it to + be freed later. */ + buffer_consume(&channels[channel].input, + buffer_len(&channels[channel].input)); + channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING; + /* debug("Setting status to output draining; output len = %d", + buffer_len(&channels[channel].output)); */ + } +} + +/* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */ + +void channel_input_close_confirmation() +{ + int channel; + + /* Get the channel number and verify it. */ + channel = packet_get_int(); + if (channel < 0 || channel >= channels_alloc) + packet_disconnect("Received close confirmation for out-of-range channel %d.", + channel); + + if(!compat13){ + /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */ + chan_rcvd_oclose(&channels[channel]); + return; + } + + if (channels[channel].type != SSH_CHANNEL_CLOSED) + packet_disconnect("Received close confirmation for non-closed channel %d (type %d).", + channel, channels[channel].type); + + /* Free the channel. */ + channel_free(channel); +} + +/* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */ + +void channel_input_open_confirmation() +{ + int channel, remote_channel; + + /* Get the channel number and verify it. */ + channel = packet_get_int(); + if (channel < 0 || channel >= channels_alloc || + channels[channel].type != SSH_CHANNEL_OPENING) + packet_disconnect("Received open confirmation for non-opening channel %d.", + channel); + + /* Get remote side's id for this channel. */ + remote_channel = packet_get_int(); + + /* Record the remote channel number and mark that the channel is now open. */ + channels[channel].remote_id = remote_channel; + channels[channel].type = SSH_CHANNEL_OPEN; +} + +/* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */ + +void channel_input_open_failure() +{ + int channel; + + /* Get the channel number and verify it. */ + channel = packet_get_int(); + if (channel < 0 || channel >= channels_alloc || + channels[channel].type != SSH_CHANNEL_OPENING) + packet_disconnect("Received open failure for non-opening channel %d.", + channel); + + /* Free the channel. This will also close the socket. */ + channel_free(channel); +} + +/* Stops listening for channels, and removes any unix domain sockets that + we might have. */ + +void channel_stop_listening() +{ + int i; + for (i = 0; i < channels_alloc; i++) + { + switch (channels[i].type) + { + case SSH_CHANNEL_AUTH_SOCKET: + close(channels[i].sock); + remove(channels[i].path); + channel_free(i); + break; + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_X11_LISTENER: + close(channels[i].sock); + channel_free(i); + break; + default: + break; + } + } +} + +/* Closes the sockets of all channels. This is used to close extra file + descriptors after a fork. */ + +void channel_close_all() +{ + int i; + for (i = 0; i < channels_alloc; i++) + { + if (channels[i].type != SSH_CHANNEL_FREE) + close(channels[i].sock); + } +} + +/* Returns the maximum file descriptor number used by the channels. */ + +int channel_max_fd() +{ + return channel_max_fd_value; +} + +/* Returns true if any channel is still open. */ + +int channel_still_open() +{ + unsigned int i; + for (i = 0; i < channels_alloc; i++) + switch (channels[i].type) + { + case SSH_CHANNEL_FREE: + case SSH_CHANNEL_X11_LISTENER: + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_CLOSED: + case SSH_CHANNEL_AUTH_SOCKET: + continue; + case SSH_CHANNEL_OPENING: + case SSH_CHANNEL_OPEN: + case SSH_CHANNEL_X11_OPEN: + return 1; + case SSH_CHANNEL_INPUT_DRAINING: + case SSH_CHANNEL_OUTPUT_DRAINING: + if (!compat13) + fatal("cannot happen: OUT_DRAIN"); + return 1; + default: + fatal("channel_still_open: bad channel type %d", channels[i].type); + /*NOTREACHED*/ + } + return 0; +} + +/* Returns a message describing the currently open forwarded + connections, suitable for sending to the client. The message + contains crlf pairs for newlines. */ + +char *channel_open_message() +{ + Buffer buffer; + int i; + char buf[512], *cp; + + buffer_init(&buffer); + snprintf(buf, sizeof buf, "The following connections are open:\r\n"); + buffer_append(&buffer, buf, strlen(buf)); + for (i = 0; i < channels_alloc; i++){ + Channel *c=&channels[i]; + switch (c->type) + { + case SSH_CHANNEL_FREE: + case SSH_CHANNEL_X11_LISTENER: + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_CLOSED: + case SSH_CHANNEL_AUTH_SOCKET: + continue; + case SSH_CHANNEL_OPENING: + case SSH_CHANNEL_OPEN: + case SSH_CHANNEL_X11_OPEN: + case SSH_CHANNEL_INPUT_DRAINING: + case SSH_CHANNEL_OUTPUT_DRAINING: + snprintf(buf, sizeof buf, " #%d/%d %.300s\r\n", + c->self,c->type,c->remote_name); + buffer_append(&buffer, buf, strlen(buf)); + continue; + default: + fatal("channel_still_open: bad channel type %d", c->type); + /*NOTREACHED*/ + } + } + buffer_append(&buffer, "\0", 1); + cp = xstrdup(buffer_ptr(&buffer)); + buffer_free(&buffer); + return cp; +} + +/* Initiate forwarding of connections to local port "port" through the secure + channel to host:port from remote side. */ + +void channel_request_local_forwarding(int port, const char *host, + int host_port) +{ + int ch, sock; + struct sockaddr_in sin; + extern Options options; + + if (strlen(host) > sizeof(channels[0].path) - 1) + packet_disconnect("Forward host name too long."); + + /* Create a port to listen for the host. */ + sock = socket(AF_INET, SOCK_STREAM, 0); + if (sock < 0) + packet_disconnect("socket: %.100s", strerror(errno)); + + /* Initialize socket address. */ + memset(&sin, 0, sizeof(sin)); + sin.sin_family = AF_INET; + if (options.gateway_ports == 1) + sin.sin_addr.s_addr = htonl(INADDR_ANY); + else + sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK); + sin.sin_port = htons(port); + + /* Bind the socket to the address. */ + if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) + packet_disconnect("bind: %.100s", strerror(errno)); + + /* Start listening for connections on the socket. */ + if (listen(sock, 5) < 0) + packet_disconnect("listen: %.100s", strerror(errno)); + + /* Allocate a channel number for the socket. */ + ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock, + xstrdup("port listener")); + strcpy(channels[ch].path, host); /* note: host name stored here */ + channels[ch].host_port = host_port; /* port on host to connect to */ + channels[ch].listening_port = port; /* port being listened */ +} + +/* Initiate forwarding of connections to port "port" on remote host through + the secure channel to host:port from local side. */ + +void channel_request_remote_forwarding(int port, const char *host, + int remote_port) +{ + int payload_len; + /* Record locally that connection to this host/port is permitted. */ + if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION) + fatal("channel_request_remote_forwarding: too many forwards"); + permitted_opens[num_permitted_opens].host = xstrdup(host); + permitted_opens[num_permitted_opens].port = remote_port; + num_permitted_opens++; + + /* Send the forward request to the remote side. */ + packet_start(SSH_CMSG_PORT_FORWARD_REQUEST); + packet_put_int(port); + packet_put_string(host, strlen(host)); + packet_put_int(remote_port); + packet_send(); + packet_write_wait(); + + /* Wait for response from the remote side. It will send a disconnect + message on failure, and we will never see it here. */ + packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); +} + +/* This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates + listening for the port, and sends back a success reply (or disconnect + message if there was an error). This never returns if there was an + error. */ + +void channel_input_port_forward_request(int is_root) +{ + int port, host_port; + char *hostname; + + /* Get arguments from the packet. */ + port = packet_get_int(); + hostname = packet_get_string(NULL); + host_port = packet_get_int(); + + /* Port numbers are 16 bit quantities. */ + if ((port & 0xffff) != port) + packet_disconnect("Requested forwarding of nonexistent port %d.", port); + + /* Check that an unprivileged user is not trying to forward a privileged + port. */ + if (port < IPPORT_RESERVED && !is_root) + packet_disconnect("Requested forwarding of port %d but user is not root.", + port); + + /* Initiate forwarding. */ + channel_request_local_forwarding(port, hostname, host_port); + + /* Free the argument string. */ + xfree(hostname); +} + +/* This is called after receiving PORT_OPEN message. This attempts to connect + to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION or + CHANNEL_OPEN_FAILURE. */ + +void channel_input_port_open(int payload_len) +{ + int remote_channel, sock, newch, host_port, i; + struct sockaddr_in sin; + char *host, *originator_string; + struct hostent *hp; + int host_len, originator_len; + + /* Get remote channel number. */ + remote_channel = packet_get_int(); + + /* Get host name to connect to. */ + host = packet_get_string(&host_len); + + /* Get port to connect to. */ + host_port = packet_get_int(); + + /* Get remote originator name. */ + if (have_hostname_in_open) + originator_string = packet_get_string(&originator_len); + else + originator_string = xstrdup("unknown (remote did not supply name)"); + + packet_integrity_check(payload_len, + 4 + 4 + host_len + 4 + 4 + originator_len, + SSH_MSG_PORT_OPEN); + + /* Check if opening that port is permitted. */ + if (!all_opens_permitted) + { + /* Go trough all permitted ports. */ + for (i = 0; i < num_permitted_opens; i++) + if (permitted_opens[i].port == host_port && + strcmp(permitted_opens[i].host, host) == 0) + break; + + /* Check if we found the requested port among those permitted. */ + if (i >= num_permitted_opens) + { + /* The port is not permitted. */ + log("Received request to connect to %.100s:%d, but the request was denied.", + host, host_port); + packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); + packet_put_int(remote_channel); + packet_send(); + } + } + + memset(&sin, 0, sizeof(sin)); + sin.sin_addr.s_addr = inet_addr(host); + if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) + { + /* It was a valid numeric host address. */ + sin.sin_family = AF_INET; + } + else + { + /* Look up the host address from the name servers. */ + hp = gethostbyname(host); + if (!hp) + { + error("%.100s: unknown host.", host); + goto fail; + } + if (!hp->h_addr_list[0]) + { + error("%.100s: host has no IP address.", host); + goto fail; + } + sin.sin_family = hp->h_addrtype; + memcpy(&sin.sin_addr, hp->h_addr_list[0], + sizeof(sin.sin_addr)); + } + sin.sin_port = htons(host_port); + + /* Create the socket. */ + sock = socket(sin.sin_family, SOCK_STREAM, 0); + if (sock < 0) + { + error("socket: %.100s", strerror(errno)); + goto fail; + } + + /* Connect to the host/port. */ + if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) + { + error("connect %.100s:%d: %.100s", host, host_port, + strerror(errno)); + close(sock); + goto fail; + } + + /* Successful connection. */ + + /* Allocate a channel for this connection. */ + newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string); + channels[newch].remote_id = remote_channel; + + /* Send a confirmation to the remote host. */ + packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); + packet_put_int(remote_channel); + packet_put_int(newch); + packet_send(); + + /* Free the argument string. */ + xfree(host); + + return; + + fail: + /* Free the argument string. */ + xfree(host); + + /* Send refusal to the remote host. */ + packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); + packet_put_int(remote_channel); + packet_send(); +} + +/* Creates an internet domain socket for listening for X11 connections. + Returns a suitable value for the DISPLAY variable, or NULL if an error + occurs. */ + +char *x11_create_display_inet(int screen_number) +{ + extern ServerOptions options; + int display_number, port, sock; + struct sockaddr_in sin; + char buf[512]; + char hostname[MAXHOSTNAMELEN]; + + for (display_number = options.x11_display_offset; display_number < MAX_DISPLAYS; display_number++) + { + port = 6000 + display_number; + memset(&sin, 0, sizeof(sin)); + sin.sin_family = AF_INET; + sin.sin_addr.s_addr = htonl(INADDR_ANY); + sin.sin_port = htons(port); + + sock = socket(AF_INET, SOCK_STREAM, 0); + if (sock < 0) + { + error("socket: %.100s", strerror(errno)); + return NULL; + } + + if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) + { + debug("bind port %d: %.100s", port, strerror(errno)); + shutdown(sock, SHUT_RDWR); + close(sock); + continue; + } + break; + } + if (display_number >= MAX_DISPLAYS) + { + error("Failed to allocate internet-domain X11 display socket."); + return NULL; + } + + /* Start listening for connections on the socket. */ + if (listen(sock, 5) < 0) + { + error("listen: %.100s", strerror(errno)); + shutdown(sock, SHUT_RDWR); + close(sock); + return NULL; + } + + /* Set up a suitable value for the DISPLAY variable. */ + if (gethostname(hostname, sizeof(hostname)) < 0) + fatal("gethostname: %.100s", strerror(errno)); + snprintf(buf, sizeof buf, "%.400s:%d.%d", hostname, + display_number, screen_number); + + /* Allocate a channel for the socket. */ + (void)channel_allocate(SSH_CHANNEL_X11_LISTENER, sock, + xstrdup("X11 inet listener")); + + /* Return a suitable value for the DISPLAY environment variable. */ + return xstrdup(buf); +} + +#ifndef X_UNIX_PATH +#define X_UNIX_PATH "/tmp/.X11-unix/X" +#endif + +static +int +connect_local_xsocket(unsigned dnr) +{ + static const char *const x_sockets[] = { + X_UNIX_PATH "%u", + "/var/X/.X11-unix/X" "%u", + "/usr/spool/sockets/X11/" "%u", + NULL + }; + int sock; + struct sockaddr_un addr; + const char *const *path; + + for (path = x_sockets; *path; ++path) + { + sock = socket(AF_UNIX, SOCK_STREAM, 0); + if (sock < 0) + error("socket: %.100s", strerror(errno)); + memset(&addr, 0, sizeof(addr)); + addr.sun_family = AF_UNIX; + snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr); + if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0) + return sock; + close(sock); + } + error("connect %.100s: %.100s", addr.sun_path, strerror(errno)); + return -1; +} + + +/* This is called when SSH_SMSG_X11_OPEN is received. The packet contains + the remote channel number. We should do whatever we want, and respond + with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. */ + +void x11_input_open(int payload_len) +{ + int remote_channel, display_number, sock, newch; + const char *display; + struct sockaddr_in sin; + char buf[1024], *cp, *remote_host; + struct hostent *hp; + int remote_len; + + /* Get remote channel number. */ + remote_channel = packet_get_int(); + + /* Get remote originator name. */ + if (have_hostname_in_open) + remote_host = packet_get_string(&remote_len); + else + remote_host = xstrdup("unknown (remote did not supply name)"); + + debug("Received X11 open request."); + packet_integrity_check(payload_len, 4 + 4+remote_len, SSH_SMSG_X11_OPEN); + + /* Try to open a socket for the local X server. */ + display = getenv("DISPLAY"); + if (!display) + { + error("DISPLAY not set."); + goto fail; + } + + /* Now we decode the value of the DISPLAY variable and make a connection + to the real X server. */ + + /* Check if it is a unix domain socket. Unix domain displays are in one + of the following formats: unix:d[.s], :d[.s], ::d[.s] */ + if (strncmp(display, "unix:", 5) == 0 || + display[0] == ':') + { + /* Connect to the unix domain socket. */ + if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) + { + error("Could not parse display number from DISPLAY: %.100s", + display); + goto fail; + } + /* Create a socket. */ + sock = connect_local_xsocket(display_number); + if (sock < 0) + goto fail; + + /* OK, we now have a connection to the display. */ + goto success; + } + + /* Connect to an inet socket. The DISPLAY value is supposedly + hostname:d[.s], where hostname may also be numeric IP address. */ + strncpy(buf, display, sizeof(buf)); + buf[sizeof(buf) - 1] = 0; + cp = strchr(buf, ':'); + if (!cp) + { + error("Could not find ':' in DISPLAY: %.100s", display); + goto fail; + } + *cp = 0; + /* buf now contains the host name. But first we parse the display number. */ + if (sscanf(cp + 1, "%d", &display_number) != 1) + { + error("Could not parse display number from DISPLAY: %.100s", + display); + goto fail; + } + + /* Try to parse the host name as a numeric IP address. */ + memset(&sin, 0, sizeof(sin)); + sin.sin_addr.s_addr = inet_addr(buf); + if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) + { + /* It was a valid numeric host address. */ + sin.sin_family = AF_INET; + } + else + { + /* Not a numeric IP address. */ + /* Look up the host address from the name servers. */ + hp = gethostbyname(buf); + if (!hp) + { + error("%.100s: unknown host.", buf); + goto fail; + } + if (!hp->h_addr_list[0]) + { + error("%.100s: host has no IP address.", buf); + goto fail; + } + sin.sin_family = hp->h_addrtype; + memcpy(&sin.sin_addr, hp->h_addr_list[0], + sizeof(sin.sin_addr)); + } + /* Set port number. */ + sin.sin_port = htons(6000 + display_number); + + /* Create a socket. */ + sock = socket(sin.sin_family, SOCK_STREAM, 0); + if (sock < 0) + { + error("socket: %.100s", strerror(errno)); + goto fail; + } + /* Connect it to the display. */ + if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) + { + error("connect %.100s:%d: %.100s", buf, 6000 + display_number, + strerror(errno)); + close(sock); + goto fail; + } + + success: + /* We have successfully obtained a connection to the real X display. */ + + /* Allocate a channel for this connection. */ + if (x11_saved_proto == NULL) + newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host); + else + newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host); + channels[newch].remote_id = remote_channel; + + /* Send a confirmation to the remote host. */ + packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); + packet_put_int(remote_channel); + packet_put_int(newch); + packet_send(); + + return; + + fail: + /* Send refusal to the remote host. */ + packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); + packet_put_int(remote_channel); + packet_send(); +} + +/* Requests forwarding of X11 connections, generates fake authentication + data, and enables authentication spoofing. */ + +void x11_request_forwarding_with_spoofing(const char *proto, const char *data) +{ + unsigned int data_len = (unsigned int)strlen(data) / 2; + unsigned int i, value; + char *new_data; + int screen_number; + const char *cp; + u_int32_t rand = 0; + + cp = getenv("DISPLAY"); + if (cp) + cp = strchr(cp, ':'); + if (cp) + cp = strchr(cp, '.'); + if (cp) + screen_number = atoi(cp + 1); + else + screen_number = 0; + + /* Save protocol name. */ + x11_saved_proto = xstrdup(proto); + + /* Extract real authentication data and generate fake data of the same + length. */ + x11_saved_data = xmalloc(data_len); + x11_fake_data = xmalloc(data_len); + for (i = 0; i < data_len; i++) + { + if (sscanf(data + 2 * i, "%2x", &value) != 1) + fatal("x11_request_forwarding: bad authentication data: %.100s", data); + if (i % 4 == 0) + rand = arc4random(); + x11_saved_data[i] = value; + x11_fake_data[i] = rand & 0xff; + rand >>= 8; + } + x11_saved_data_len = data_len; + x11_fake_data_len = data_len; + + /* Convert the fake data into hex. */ + new_data = xmalloc(2 * data_len + 1); + for (i = 0; i < data_len; i++) + sprintf(new_data + 2 * i, "%02x", (unsigned char)x11_fake_data[i]); + + /* Send the request packet. */ + packet_start(SSH_CMSG_X11_REQUEST_FORWARDING); + packet_put_string(proto, strlen(proto)); + packet_put_string(new_data, strlen(new_data)); + packet_put_int(screen_number); + packet_send(); + packet_write_wait(); + xfree(new_data); +} + +/* Sends a message to the server to request authentication fd forwarding. */ + +void auth_request_forwarding() +{ + packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING); + packet_send(); + packet_write_wait(); +} + +/* Returns the name of the forwarded authentication socket. Returns NULL + if there is no forwarded authentication socket. The returned value + points to a static buffer. */ + +char *auth_get_socket_name() +{ + return channel_forwarded_auth_socket_name; +} + +/* removes the agent forwarding socket */ + +void cleanup_socket(void) { + remove(channel_forwarded_auth_socket_name); + rmdir(channel_forwarded_auth_socket_dir); +} + +/* This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. + This starts forwarding authentication requests. */ + +void auth_input_request_forwarding(struct passwd *pw) +{ + int sock, newch; + struct sockaddr_un sunaddr; + + if (auth_get_socket_name() != NULL) + fatal("Protocol error: authentication forwarding requested twice."); + + /* Temporarily drop privileged uid for mkdir/bind. */ + temporarily_use_uid(pw->pw_uid); + + /* Allocate a buffer for the socket name, and format the name. */ + channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME); + channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME); + strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME); + + /* Create private directory for socket */ + if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL) + packet_disconnect("mkdtemp: %.100s", strerror(errno)); + snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, + "%s/agent.%d", channel_forwarded_auth_socket_dir, (int)getpid()); + + if (atexit(cleanup_socket) < 0) { + int saved=errno; + cleanup_socket(); + packet_disconnect("socket: %.100s", strerror(saved)); + } + + /* Create the socket. */ + sock = socket(AF_UNIX, SOCK_STREAM, 0); + if (sock < 0) + packet_disconnect("socket: %.100s", strerror(errno)); + + /* Bind it to the name. */ + memset(&sunaddr, 0, sizeof(sunaddr)); + sunaddr.sun_family = AF_UNIX; + strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name, + sizeof(sunaddr.sun_path)); + + if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) + packet_disconnect("bind: %.100s", strerror(errno)); + + /* Restore the privileged uid. */ + restore_uid(); + + /* Start listening on the socket. */ + if (listen(sock, 5) < 0) + packet_disconnect("listen: %.100s", strerror(errno)); + + /* Allocate a channel for the authentication agent socket. */ + newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock, + xstrdup("auth socket")); + strcpy(channels[newch].path, channel_forwarded_auth_socket_name); +} + +/* This is called to process an SSH_SMSG_AGENT_OPEN message. */ + +void auth_input_open_request() +{ + int remch, sock, newch; + char *dummyname; + + /* Read the remote channel number from the message. */ + remch = packet_get_int(); + + /* Get a connection to the local authentication agent (this may again get + forwarded). */ + sock = ssh_get_authentication_socket(); + + /* If we could not connect the agent, send an error message back to + the server. This should never happen unless the agent + dies, because authentication forwarding is only enabled if we have an + agent. */ + if (sock < 0){ + packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); + packet_put_int(remch); + packet_send(); + return; + } + + debug("Forwarding authentication connection."); + + /* Dummy host name. This will be freed when the channel is freed; it will + still be valid in the packet_put_string below since the channel cannot + yet be freed at that point. */ + dummyname = xstrdup("authentication agent connection"); + + newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname); + channels[newch].remote_id = remch; + + /* Send a confirmation to the remote host. */ + packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); + packet_put_int(remch); + packet_put_int(newch); + packet_send(); +} diff --git a/channels.h b/channels.h new file mode 100644 index 00000000..c0b4a934 --- /dev/null +++ b/channels.h @@ -0,0 +1,41 @@ +/* RCSID("$Id$"); */ + +#ifndef CHANNELS_H +#define CHANNELS_H + +/* Definitions for channel types. */ +#define SSH_CHANNEL_FREE 0 /* This channel is free (unused). */ +#define SSH_CHANNEL_X11_LISTENER 1 /* Listening for inet X11 conn. */ +#define SSH_CHANNEL_PORT_LISTENER 2 /* Listening on a port. */ +#define SSH_CHANNEL_OPENING 3 /* waiting for confirmation */ +#define SSH_CHANNEL_OPEN 4 /* normal open two-way channel */ +#define SSH_CHANNEL_CLOSED 5 /* waiting for close confirmation */ +/* SSH_CHANNEL_AUTH_FD 6 authentication fd */ +#define SSH_CHANNEL_AUTH_SOCKET 7 /* authentication socket */ +/* SSH_CHANNEL_AUTH_SOCKET_FD 8 connection to auth socket */ +#define SSH_CHANNEL_X11_OPEN 9 /* reading first X11 packet */ +#define SSH_CHANNEL_INPUT_DRAINING 10 /* sending remaining data to conn */ +#define SSH_CHANNEL_OUTPUT_DRAINING 11 /* sending remaining data to app */ + +/* Data structure for channel data. This is iniailized in channel_allocate + and cleared in channel_free. */ + +typedef struct Channel +{ + int type; /* channel type/state */ + int self; /* my own channel identifier */ + int remote_id; /* channel identifier for remote peer */ + /* peer can be reached over encrypted connection, via packet-sent */ + int istate; + int ostate; + int x11; + int sock; /* data socket, linked to this channel */ + Buffer input; /* data read from socket, to be sent over encrypted connection */ + Buffer output; /* data received over encrypted connection for send on socket */ + char path[200]; /* path for unix domain sockets, or host name for forwards */ + int listening_port; /* port being listened for forwards */ + int host_port; /* remote port to connect for forwards */ + char *remote_name; /* remote hostname */ +} Channel; + +#endif diff --git a/cipher.c b/cipher.c new file mode 100644 index 00000000..ac64a30d --- /dev/null +++ b/cipher.c @@ -0,0 +1,304 @@ +/* + +cipher.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Apr 19 17:41:39 1995 ylo + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include "cipher.h" + +#include + +/* + * What kind of tripple DES are these 2 routines? + * + * Why is there a redundant initialization vector? + * + * If only iv3 was used, then, this would till effect have been + * outer-cbc. However, there is also a private iv1 == iv2 which + * perhaps makes differential analysis easier. On the other hand, the + * private iv1 probably makes the CRC-32 attack ineffective. This is a + * result of that there is no longer any known iv1 to use when + * choosing the X block. + */ +void +SSH_3CBC_ENCRYPT(des_key_schedule ks1, + des_key_schedule ks2, des_cblock *iv2, + des_key_schedule ks3, des_cblock *iv3, + void *dest, void *src, + unsigned int len) +{ + des_cblock iv1; + + memcpy(&iv1, iv2, 8); + + des_cbc_encrypt(src, dest, len, ks1, &iv1, DES_ENCRYPT); + memcpy(&iv1, dest + len - 8, 8); + + des_cbc_encrypt(dest, dest, len, ks2, iv2, DES_DECRYPT); + memcpy(iv2, &iv1, 8); /* Note how iv1 == iv2 on entry and exit. */ + + des_cbc_encrypt(dest, dest, len, ks3, iv3, DES_ENCRYPT); + memcpy(iv3, dest + len - 8, 8); +} + +void +SSH_3CBC_DECRYPT(des_key_schedule ks1, + des_key_schedule ks2, des_cblock *iv2, + des_key_schedule ks3, des_cblock *iv3, + void *dest, void *src, + unsigned int len) +{ + des_cblock iv1; + + memcpy(&iv1, iv2, 8); + + des_cbc_encrypt(src, dest, len, ks3, iv3, DES_DECRYPT); + memcpy(iv3, src + len - 8, 8); + + des_cbc_encrypt(dest, dest, len, ks2, iv2, DES_ENCRYPT); + memcpy(iv2, dest + len - 8, 8); + + des_cbc_encrypt(dest, dest, len, ks1, &iv1, DES_DECRYPT); + /* memcpy(&iv1, iv2, 8); */ /* Note how iv1 == iv2 on entry and exit. */ +} + +/* + * SSH uses a variation on Blowfish, all bytes must be swapped before + * and after encryption/decryption. Thus the swap_bytes stuff (yuk). + */ +static +void +swap_bytes(const unsigned char *src, unsigned char *dst_, int n) +{ + u_int32_t *dst = (u_int32_t *)dst_; /* dst must be properly aligned. */ + union { + u_int32_t i; + char c[4]; + } t; + + /* assert((n & 7) == 0); */ + + /* Process 8 bytes every lap. */ + for (n = n / 8; n > 0; n--) + { + t.c[3] = *src++; + t.c[2] = *src++; + t.c[1] = *src++; + t.c[0] = *src++; + *dst++ = t.i; + + t.c[3] = *src++; + t.c[2] = *src++; + t.c[1] = *src++; + t.c[0] = *src++; + *dst++ = t.i; + } +} + +void (*cipher_attack_detected)(const char *fmt, ...) = fatal; + +static inline +void +detect_cbc_attack(const unsigned char *src, + unsigned int len) +{ + return; + + log("CRC-32 CBC insertion attack detected"); + cipher_attack_detected("CRC-32 CBC insertion attack detected"); +} + +/* Names of all encryption algorithms. These must match the numbers defined + int cipher.h. */ +static char *cipher_names[] = +{ + "none", + "idea", + "des", + "3des", + "tss", + "rc4", + "blowfish" +}; + +/* Returns a bit mask indicating which ciphers are supported by this + implementation. The bit mask has the corresponding bit set of each + supported cipher. */ + +unsigned int cipher_mask() +{ + unsigned int mask = 0; + mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ + mask |= 1 << SSH_CIPHER_BLOWFISH; + return mask; +} + +/* Returns the name of the cipher. */ + +const +char *cipher_name(int cipher) +{ + if (cipher < 0 || cipher >= sizeof(cipher_names) / sizeof(cipher_names[0]) || + cipher_names[cipher] == NULL) + fatal("cipher_name: bad cipher number: %d", cipher); + return cipher_names[cipher]; +} + +/* Parses the name of the cipher. Returns the number of the corresponding + cipher, or -1 on error. */ + +int +cipher_number(const char *name) +{ + int i; + for (i = 0; i < sizeof(cipher_names) / sizeof(cipher_names[0]); i++) + if (strcmp(cipher_names[i], name) == 0 && + (cipher_mask() & (1 << i))) + return i; + return -1; +} + +/* Selects the cipher, and keys if by computing the MD5 checksum of the + passphrase and using the resulting 16 bytes as the key. */ + +void cipher_set_key_string(CipherContext *context, int cipher, + const char *passphrase, int for_encryption) +{ + MD5_CTX md; + unsigned char digest[16]; + + MD5_Init(&md); + MD5_Update(&md, (const unsigned char *)passphrase, strlen(passphrase)); + MD5_Final(digest, &md); + + cipher_set_key(context, cipher, digest, 16, for_encryption); + + memset(digest, 0, sizeof(digest)); + memset(&md, 0, sizeof(md)); +} + +/* Selects the cipher to use and sets the key. */ + +void cipher_set_key(CipherContext *context, int cipher, + const unsigned char *key, int keylen, int for_encryption) +{ + unsigned char padded[32]; + + /* Set cipher type. */ + context->type = cipher; + + /* Get 32 bytes of key data. Pad if necessary. (So that code below does + not need to worry about key size). */ + memset(padded, 0, sizeof(padded)); + memcpy(padded, key, keylen < sizeof(padded) ? keylen : sizeof(padded)); + + /* Initialize the initialization vector. */ + switch (cipher) + { + case SSH_CIPHER_NONE: + /* Has to stay for authfile saving of private key with no passphrase */ + break; + + case SSH_CIPHER_3DES: + /* Note: the least significant bit of each byte of key is parity, + and must be ignored by the implementation. 16 bytes of key are + used (first and last keys are the same). */ + if (keylen < 16) + error("Key length %d is insufficient for 3DES.", keylen); + des_set_key((void*)padded, context->u.des3.key1); + des_set_key((void*)(padded + 8), context->u.des3.key2); + if (keylen <= 16) + des_set_key((void*)padded, context->u.des3.key3); + else + des_set_key((void*)(padded + 16), context->u.des3.key3); + memset(context->u.des3.iv2, 0, sizeof(context->u.des3.iv2)); + memset(context->u.des3.iv3, 0, sizeof(context->u.des3.iv3)); + break; + + case SSH_CIPHER_BLOWFISH: + BF_set_key(&context->u.bf.key, keylen, padded); + memset(context->u.bf.iv, 0, 8); + break; + + default: + fatal("cipher_set_key: unknown cipher: %d", cipher); + } + memset(padded, 0, sizeof(padded)); +} + +/* Encrypts data using the cipher. */ + +void cipher_encrypt(CipherContext *context, unsigned char *dest, + const unsigned char *src, unsigned int len) +{ + assert((len & 7) == 0); + + switch (context->type) + { + case SSH_CIPHER_NONE: + memcpy(dest, src, len); + break; + + case SSH_CIPHER_3DES: + SSH_3CBC_ENCRYPT(context->u.des3.key1, + context->u.des3.key2, &context->u.des3.iv2, + context->u.des3.key3, &context->u.des3.iv3, + dest, (void*)src, len); + break; + + case SSH_CIPHER_BLOWFISH: + swap_bytes(src, dest, len); + BF_cbc_encrypt(dest, dest, len, + &context->u.bf.key, context->u.bf.iv, BF_ENCRYPT); + swap_bytes(dest, dest, len); + break; + + default: + fatal("cipher_encrypt: unknown cipher: %d", context->type); + } +} + +/* Decrypts data using the cipher. */ + +void cipher_decrypt(CipherContext *context, unsigned char *dest, + const unsigned char *src, unsigned int len) +{ + assert((len & 7) == 0); + + switch (context->type) + { + case SSH_CIPHER_NONE: + memcpy(dest, src, len); + break; + + case SSH_CIPHER_3DES: + /* CRC-32 attack? */ + SSH_3CBC_DECRYPT(context->u.des3.key1, + context->u.des3.key2, &context->u.des3.iv2, + context->u.des3.key3, &context->u.des3.iv3, + dest, (void*)src, len); + break; + + case SSH_CIPHER_BLOWFISH: + detect_cbc_attack(src, len); + swap_bytes(src, dest, len); + BF_cbc_encrypt((void*)dest, dest, len, + &context->u.bf.key, context->u.bf.iv, BF_DECRYPT); + swap_bytes(dest, dest, len); + break; + + default: + fatal("cipher_decrypt: unknown cipher: %d", context->type); + } +} diff --git a/cipher.h b/cipher.h new file mode 100644 index 00000000..bded6243 --- /dev/null +++ b/cipher.h @@ -0,0 +1,84 @@ +/* + +cipher.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Apr 19 16:50:42 1995 ylo + +*/ + +/* RCSID("$Id$"); */ + +#ifndef CIPHER_H +#define CIPHER_H + +#include +#include + +/* Cipher types. New types can be added, but old types should not be removed + for compatibility. The maximum allowed value is 31. */ +#define SSH_CIPHER_NOT_SET -1 /* None selected (invalid number). */ +#define SSH_CIPHER_NONE 0 /* no encryption */ +#define SSH_CIPHER_IDEA 1 /* IDEA CFB */ +#define SSH_CIPHER_DES 2 /* DES CBC */ +#define SSH_CIPHER_3DES 3 /* 3DES CBC */ +#define SSH_CIPHER_TSS 4 /* TRI's Simple Stream encryption CBC */ +#define SSH_CIPHER_RC4 5 /* Alleged RC4 */ +#define SSH_CIPHER_BLOWFISH 6 + +typedef struct { + unsigned int type; + union { + struct { + des_key_schedule key1; + des_key_schedule key2; + des_cblock iv2; + des_key_schedule key3; + des_cblock iv3; + } des3; + struct { + struct bf_key_st key; + unsigned char iv[8]; + } bf; + } u; +} CipherContext; + +/* Returns a bit mask indicating which ciphers are supported by this + implementation. The bit mask has the corresponding bit set of each + supported cipher. */ +unsigned int cipher_mask(); + +/* Returns the name of the cipher. */ +const char *cipher_name(int cipher); + +/* Parses the name of the cipher. Returns the number of the corresponding + cipher, or -1 on error. */ +int cipher_number(const char *name); + +/* Selects the cipher to use and sets the key. If for_encryption is true, + the key is setup for encryption; otherwise it is setup for decryption. */ +void cipher_set_key(CipherContext *context, int cipher, + const unsigned char *key, int keylen, int for_encryption); + +/* Sets key for the cipher by computing the MD5 checksum of the passphrase, + and using the resulting 16 bytes as the key. */ +void cipher_set_key_string(CipherContext *context, int cipher, + const char *passphrase, int for_encryption); + +/* Encrypts data using the cipher. */ +void cipher_encrypt(CipherContext *context, unsigned char *dest, + const unsigned char *src, unsigned int len); + +/* Decrypts data using the cipher. */ +void cipher_decrypt(CipherContext *context, unsigned char *dest, + const unsigned char *src, unsigned int len); + +/* If and CRC-32 attack is detected this function is called. Defaults + * to fatal, changed to packet_disconnect in sshd and ssh. */ +extern void (*cipher_attack_detected)(const char *fmt, ...); + +#endif /* CIPHER_H */ diff --git a/clientloop.c b/clientloop.c new file mode 100644 index 00000000..b797f819 --- /dev/null +++ b/clientloop.c @@ -0,0 +1,924 @@ +/* + +clientloop.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + + +Created: Sat Sep 23 12:23:57 1995 ylo + +The main loop for the interactive session (client side). + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "xmalloc.h" +#include "ssh.h" +#include "packet.h" +#include "buffer.h" +#include "authfd.h" + +/* Flag indicating whether quiet mode is on. */ +extern int quiet_flag; + +/* Flag indicating that stdin should be redirected from /dev/null. */ +extern int stdin_null_flag; + +/* Name of the host we are connecting to. This is the name given on the + command line, or the HostName specified for the user-supplied name + in a configuration file. */ +extern char *host; + +/* Flag to indicate that we have received a window change signal which has + not yet been processed. This will cause a message indicating the new + window size to be sent to the server a little later. This is volatile + because this is updated in a signal handler. */ +static volatile int received_window_change_signal = 0; + +/* Terminal modes, as saved by enter_raw_mode. */ +static struct termios saved_tio; + +/* Flag indicating whether we are in raw mode. This is used by enter_raw_mode + and leave_raw_mode. */ +static int in_raw_mode = 0; + +/* Flag indicating whether the user\'s terminal is in non-blocking mode. */ +static int in_non_blocking_mode = 0; + +/* Common data for the client loop code. */ +static int escape_pending; /* Last character was the escape character */ +static int last_was_cr; /* Last character was a newline. */ +static int exit_status; /* Used to store the exit status of the command. */ +static int stdin_eof; /* EOF has been encountered on standard error. */ +static Buffer stdin_buffer; /* Buffer for stdin data. */ +static Buffer stdout_buffer; /* Buffer for stdout data. */ +static Buffer stderr_buffer; /* Buffer for stderr data. */ +static unsigned int buffer_high; /* Soft max buffer size. */ +static int max_fd; /* Maximum file descriptor number in select(). */ +static int connection_in; /* Connection to server (input). */ +static int connection_out; /* Connection to server (output). */ +static unsigned long stdin_bytes, stdout_bytes, stderr_bytes; +static int quit_pending; /* Set to non-zero to quit the client loop. */ +static int escape_char; /* Escape character. */ + +/* Returns the user\'s terminal to normal mode if it had been put in raw + mode. */ + +void leave_raw_mode() +{ + if (!in_raw_mode) + return; + in_raw_mode = 0; + if (tcsetattr(fileno(stdin), TCSADRAIN, &saved_tio) < 0) + perror("tcsetattr"); + + fatal_remove_cleanup((void (*)(void *))leave_raw_mode, NULL); +} + +/* Puts the user\'s terminal in raw mode. */ + +void enter_raw_mode() +{ + struct termios tio; + + if (tcgetattr(fileno(stdin), &tio) < 0) + perror("tcgetattr"); + saved_tio = tio; + tio.c_iflag |= IGNPAR; + tio.c_iflag &= ~(ISTRIP|INLCR|IGNCR|ICRNL|IXON|IXANY|IXOFF); + tio.c_lflag &= ~(ISIG|ICANON|ECHO|ECHOE|ECHOK|ECHONL); +#ifdef IEXTEN + tio.c_lflag &= ~IEXTEN; +#endif /* IEXTEN */ + tio.c_oflag &= ~OPOST; + tio.c_cc[VMIN] = 1; + tio.c_cc[VTIME] = 0; + if (tcsetattr(fileno(stdin), TCSADRAIN, &tio) < 0) + perror("tcsetattr"); + in_raw_mode = 1; + + fatal_add_cleanup((void (*)(void *))leave_raw_mode, NULL); +} + +/* Puts stdin terminal in non-blocking mode. */ + +/* Restores stdin to blocking mode. */ + +void leave_non_blocking() +{ + if (in_non_blocking_mode) + { + (void)fcntl(fileno(stdin), F_SETFL, 0); + in_non_blocking_mode = 0; + fatal_remove_cleanup((void (*)(void *))leave_non_blocking, NULL); + } +} + +void enter_non_blocking() +{ + in_non_blocking_mode = 1; + (void)fcntl(fileno(stdin), F_SETFL, O_NONBLOCK); + fatal_add_cleanup((void (*)(void *))leave_non_blocking, NULL); +} + +/* Signal handler for the window change signal (SIGWINCH). This just + sets a flag indicating that the window has changed. */ + +void window_change_handler(int sig) +{ + received_window_change_signal = 1; + signal(SIGWINCH, window_change_handler); +} + +/* Signal handler for signals that cause the program to terminate. These + signals must be trapped to restore terminal modes. */ + +void signal_handler(int sig) +{ + if (in_raw_mode) + leave_raw_mode(); + if (in_non_blocking_mode) + leave_non_blocking(); + channel_stop_listening(); + packet_close(); + fatal("Killed by signal %d.", sig); +} + +/* Returns current time in seconds from Jan 1, 1970 with the maximum available + resolution. */ + +double get_current_time() +{ + struct timeval tv; + gettimeofday(&tv, NULL); + return (double)tv.tv_sec + (double)tv.tv_usec / 1000000.0; +} + +/* This is called when the interactive is entered. This checks if there + is an EOF coming on stdin. We must check this explicitly, as select() + does not appear to wake up when redirecting from /dev/null. */ + +void client_check_initial_eof_on_stdin() +{ + int len; + char buf[1]; + + /* If standard input is to be "redirected from /dev/null", we simply + mark that we have seen an EOF and send an EOF message to the server. + Otherwise, we try to read a single character; it appears that for some + files, such /dev/null, select() never wakes up for read for this + descriptor, which means that we never get EOF. This way we will get + the EOF if stdin comes from /dev/null or similar. */ + if (stdin_null_flag) + { + /* Fake EOF on stdin. */ + debug("Sending eof."); + stdin_eof = 1; + packet_start(SSH_CMSG_EOF); + packet_send(); + } + else + { + /* Enter non-blocking mode for stdin. */ + enter_non_blocking(); + + /* Check for immediate EOF on stdin. */ + len = read(fileno(stdin), buf, 1); + if (len == 0) + { + /* EOF. Record that we have seen it and send EOF to server. */ + debug("Sending eof."); + stdin_eof = 1; + packet_start(SSH_CMSG_EOF); + packet_send(); + } + else + if (len > 0) + { + /* Got data. We must store the data in the buffer, and also + process it as an escape character if appropriate. */ + if ((unsigned char)buf[0] == escape_char) + escape_pending = 1; + else + { + buffer_append(&stdin_buffer, buf, 1); + stdin_bytes += 1; + } + } + + /* Leave non-blocking mode. */ + leave_non_blocking(); + } +} + +/* Get packets from the connection input buffer, and process them as long + as there are packets available. */ + +void client_process_buffered_input_packets() +{ + int type; + char *data; + unsigned int data_len; + int payload_len; + + /* Process any buffered packets from the server. */ + while (!quit_pending && (type = packet_read_poll(&payload_len)) != SSH_MSG_NONE) + { + switch (type) + { + + case SSH_SMSG_STDOUT_DATA: + data = packet_get_string(&data_len); + packet_integrity_check(payload_len, 4 + data_len, type); + buffer_append(&stdout_buffer, data, data_len); + stdout_bytes += data_len; + memset(data, 0, data_len); + xfree(data); + break; + + case SSH_SMSG_STDERR_DATA: + data = packet_get_string(&data_len); + packet_integrity_check(payload_len, 4 + data_len, type); + buffer_append(&stderr_buffer, data, data_len); + stdout_bytes += data_len; + memset(data, 0, data_len); + xfree(data); + break; + + case SSH_SMSG_EXITSTATUS: + packet_integrity_check(payload_len, 4, type); + exit_status = packet_get_int(); + /* Acknowledge the exit. */ + packet_start(SSH_CMSG_EXIT_CONFIRMATION); + packet_send(); + /* Must wait for packet to be sent since we are exiting the + loop. */ + packet_write_wait(); + /* Flag that we want to exit. */ + quit_pending = 1; + break; + + case SSH_SMSG_X11_OPEN: + x11_input_open(payload_len); + break; + + case SSH_MSG_PORT_OPEN: + channel_input_port_open(payload_len); + break; + + case SSH_SMSG_AGENT_OPEN: + packet_integrity_check(payload_len, 4, type); + auth_input_open_request(); + break; + + case SSH_MSG_CHANNEL_OPEN_CONFIRMATION: + packet_integrity_check(payload_len, 4 + 4, type); + channel_input_open_confirmation(); + break; + + case SSH_MSG_CHANNEL_OPEN_FAILURE: + packet_integrity_check(payload_len, 4, type); + channel_input_open_failure(); + break; + + case SSH_MSG_CHANNEL_DATA: + channel_input_data(payload_len); + break; + + case SSH_MSG_CHANNEL_CLOSE: + packet_integrity_check(payload_len, 4, type); + channel_input_close(); + break; + + case SSH_MSG_CHANNEL_CLOSE_CONFIRMATION: + packet_integrity_check(payload_len, 4, type); + channel_input_close_confirmation(); + break; + + default: + /* Any unknown packets received during the actual session + cause the session to terminate. This is intended to make + debugging easier since no confirmations are sent. Any + compatible protocol extensions must be negotiated during + the preparatory phase. */ + packet_disconnect("Protocol error during session: type %d", + type); + } + } +} + +/* Make packets from buffered stdin data, and buffer them for sending to + the connection. */ + +void client_make_packets_from_stdin_data() +{ + unsigned int len; + + /* Send buffered stdin data to the server. */ + while (buffer_len(&stdin_buffer) > 0 && + packet_not_very_much_data_to_write()) + { + len = buffer_len(&stdin_buffer); + if (len > 32768) + len = 32768; /* Keep the packets at reasonable size. */ + packet_start(SSH_CMSG_STDIN_DATA); + packet_put_string(buffer_ptr(&stdin_buffer), len); + packet_send(); + buffer_consume(&stdin_buffer, len); + /* If we have a pending EOF, send it now. */ + if (stdin_eof && buffer_len(&stdin_buffer) == 0) + { + packet_start(SSH_CMSG_EOF); + packet_send(); + } + } +} + +/* Checks if the client window has changed, and sends a packet about it to + the server if so. The actual change is detected elsewhere (by a software + interrupt on Unix); this just checks the flag and sends a message if + appropriate. */ + +void client_check_window_change() +{ + /* Send possible window change message to the server. */ + if (received_window_change_signal) + { + struct winsize ws; + + /* Clear the window change indicator. */ + received_window_change_signal = 0; + + /* Read new window size. */ + if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) >= 0) + { + /* Successful, send the packet now. */ + packet_start(SSH_CMSG_WINDOW_SIZE); + packet_put_int(ws.ws_row); + packet_put_int(ws.ws_col); + packet_put_int(ws.ws_xpixel); + packet_put_int(ws.ws_ypixel); + packet_send(); + } + } +} + +/* Waits until the client can do something (some data becomes available on + one of the file descriptors). */ + +void client_wait_until_can_do_something(fd_set *readset, fd_set *writeset) +{ + /* Initialize select masks. */ + FD_ZERO(readset); + + /* Read from the connection, unless our buffers are full. */ + if (buffer_len(&stdout_buffer) < buffer_high && + buffer_len(&stderr_buffer) < buffer_high && + channel_not_very_much_buffered_data()) + FD_SET(connection_in, readset); + + /* Read from stdin, unless we have seen EOF or have very much buffered + data to send to the server. */ + if (!stdin_eof && packet_not_very_much_data_to_write()) + FD_SET(fileno(stdin), readset); + + FD_ZERO(writeset); + + /* Add any selections by the channel mechanism. */ + channel_prepare_select(readset, writeset); + + /* Select server connection if have data to write to the server. */ + if (packet_have_data_to_write()) + FD_SET(connection_out, writeset); + + /* Select stdout if have data in buffer. */ + if (buffer_len(&stdout_buffer) > 0) + FD_SET(fileno(stdout), writeset); + + /* Select stderr if have data in buffer. */ + if (buffer_len(&stderr_buffer) > 0) + FD_SET(fileno(stderr), writeset); + + /* Update maximum file descriptor number, if appropriate. */ + if (channel_max_fd() > max_fd) + max_fd = channel_max_fd(); + + /* Wait for something to happen. This will suspend the process until + some selected descriptor can be read, written, or has some other + event pending. Note: if you want to implement SSH_MSG_IGNORE + messages to fool traffic analysis, this might be the place to do + it: just have a random timeout for the select, and send a random + SSH_MSG_IGNORE packet when the timeout expires. */ + if (select(max_fd + 1, readset, writeset, NULL, NULL) < 0) + { + char buf[100]; + /* Some systems fail to clear these automatically. */ + FD_ZERO(readset); + FD_ZERO(writeset); + if (errno == EINTR) + return; + /* Note: we might still have data in the buffers. */ + snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno)); + buffer_append(&stderr_buffer, buf, strlen(buf)); + stderr_bytes += strlen(buf); + quit_pending = 1; + } +} + +void client_suspend_self() +{ + struct winsize oldws, newws; + + /* Flush stdout and stderr buffers. */ + if (buffer_len(&stdout_buffer) > 0) + write(fileno(stdout), + buffer_ptr(&stdout_buffer), + buffer_len(&stdout_buffer)); + if (buffer_len(&stderr_buffer) > 0) + write(fileno(stderr), + buffer_ptr(&stderr_buffer), + buffer_len(&stderr_buffer)); + + /* Leave raw mode. */ + leave_raw_mode(); + + /* Free (and clear) the buffer to reduce the + amount of data that gets written to swap. */ + buffer_free(&stdin_buffer); + buffer_free(&stdout_buffer); + buffer_free(&stderr_buffer); + + /* Save old window size. */ + ioctl(fileno(stdin), TIOCGWINSZ, &oldws); + + /* Send the suspend signal to the program + itself. */ + kill(getpid(), SIGTSTP); + + /* Check if the window size has changed. */ + if (ioctl(fileno(stdin), TIOCGWINSZ, &newws) >= 0 && + (oldws.ws_row != newws.ws_row || oldws.ws_col != newws.ws_col || + oldws.ws_xpixel != newws.ws_xpixel || + oldws.ws_ypixel != newws.ws_ypixel)) + received_window_change_signal = 1; + + /* OK, we have been continued by the user. + Reinitialize buffers. */ + buffer_init(&stdin_buffer); + buffer_init(&stdout_buffer); + buffer_init(&stderr_buffer); + + /* Re-enter raw mode. */ + enter_raw_mode(); +} + +void client_process_input(fd_set *readset) +{ + int len, pid; + char buf[8192], *s; + + /* Read input from the server, and add any such data to the buffer of the + packet subsystem. */ + if (FD_ISSET(connection_in, readset)) + { + /* Read as much as possible. */ + len = read(connection_in, buf, sizeof(buf)); + if (len == 0) + { + /* Received EOF. The remote host has closed the connection. */ + snprintf(buf, sizeof buf, "Connection to %.300s closed by remote host.\r\n", + host); + buffer_append(&stderr_buffer, buf, strlen(buf)); + stderr_bytes += strlen(buf); + quit_pending = 1; + return; + } + + /* There is a kernel bug on Solaris that causes select to sometimes + wake up even though there is no data available. */ + if (len < 0 && errno == EAGAIN) + len = 0; + + if (len < 0) + { + /* An error has encountered. Perhaps there is a network + problem. */ + snprintf(buf, sizeof buf, "Read from remote host %.300s: %.100s\r\n", + host, strerror(errno)); + buffer_append(&stderr_buffer, buf, strlen(buf)); + stderr_bytes += strlen(buf); + quit_pending = 1; + return; + } + packet_process_incoming(buf, len); + } + + /* Read input from stdin. */ + if (FD_ISSET(fileno(stdin), readset)) + { + /* Read as much as possible. */ + len = read(fileno(stdin), buf, sizeof(buf)); + if (len <= 0) + { + /* Received EOF or error. They are treated similarly, + except that an error message is printed if it was + an error condition. */ + if (len < 0) + { + snprintf(buf, sizeof buf, "read: %.100s\r\n", strerror(errno)); + buffer_append(&stderr_buffer, buf, strlen(buf)); + stderr_bytes += strlen(buf); + } + /* Mark that we have seen EOF. */ + stdin_eof = 1; + /* Send an EOF message to the server unless there is data + in the buffer. If there is data in the buffer, no message + will be sent now. Code elsewhere will send the EOF + when the buffer becomes empty if stdin_eof is set. */ + if (buffer_len(&stdin_buffer) == 0) + { + packet_start(SSH_CMSG_EOF); + packet_send(); + } + } + else + if (escape_char == -1) + { + /* Normal successful read, and no escape character. Just + append the data to buffer. */ + buffer_append(&stdin_buffer, buf, len); + stdin_bytes += len; + } + else + { + /* Normal, successful read. But we have an escape character + and have to process the characters one by one. */ + unsigned int i; + for (i = 0; i < len; i++) + { + unsigned char ch; + /* Get one character at a time. */ + ch = buf[i]; + + /* Check if we have a pending escape character. */ + if (escape_pending) + { + /* We have previously seen an escape character. */ + /* Clear the flag now. */ + escape_pending = 0; + /* Process the escaped character. */ + switch (ch) + { + case '.': + /* Terminate the connection. */ + snprintf(buf, sizeof buf, "%c.\r\n", escape_char); + buffer_append(&stderr_buffer, buf, strlen(buf)); + stderr_bytes += strlen(buf); + quit_pending = 1; + return; + + case 'Z' - 64: + /* Suspend the program. */ + /* Print a message to that effect to the user. */ + snprintf(buf, sizeof buf, "%c^Z\r\n", escape_char); + buffer_append(&stderr_buffer, buf, strlen(buf)); + stderr_bytes += strlen(buf); + + /* Restore terminal modes and suspend. */ + client_suspend_self(); + + /* We have been continued. */ + continue; + + case '&': + /* Detach the program (continue to serve connections, + but put in background and no more new + connections). */ + if (!stdin_eof) + { + /* Sending SSH_CMSG_EOF alone does not always + appear to be enough. So we try to send an + EOF character first. */ + packet_start(SSH_CMSG_STDIN_DATA); + packet_put_string("\004", 1); + packet_send(); + /* Close stdin. */ + stdin_eof = 1; + if (buffer_len(&stdin_buffer) == 0) + { + packet_start(SSH_CMSG_EOF); + packet_send(); + } + } + /* Restore tty modes. */ + leave_raw_mode(); + + /* Stop listening for new connections. */ + channel_stop_listening(); + + printf("%c& [backgrounded]\n", escape_char); + + /* Fork into background. */ + pid = fork(); + if (pid < 0) + { + error("fork: %.100s", strerror(errno)); + continue; + } + if (pid != 0) + { /* This is the parent. */ + /* The parent just exits. */ + exit(0); + } + + /* The child continues serving connections. */ + continue; + + case '?': + snprintf(buf, sizeof buf, "%c?\r\n\ +Supported escape sequences:\r\n\ +~. - terminate connection\r\n\ +~^Z - suspend ssh\r\n\ +~# - list forwarded connections\r\n\ +~& - background ssh (when waiting for connections to terminate)\r\n\ +~? - this message\r\n\ +~~ - send the escape character by typing it twice\r\n\ +(Note that escapes are only recognized immediately after newline.)\r\n", + escape_char); + buffer_append(&stderr_buffer, buf, strlen(buf)); + continue; + + case '#': + snprintf(buf, sizeof buf, "%c#\r\n", escape_char); + buffer_append(&stderr_buffer, buf, strlen(buf)); + s = channel_open_message(); + buffer_append(&stderr_buffer, s, strlen(s)); + xfree(s); + continue; + + default: + if (ch != escape_char) + { + /* Escape character followed by non-special + character. Append both to the input + buffer. */ + buf[0] = escape_char; + buf[1] = ch; + buffer_append(&stdin_buffer, buf, 2); + stdin_bytes += 2; + continue; + } + /* Note that escape character typed twice falls through + here; the latter gets processed as a normal + character below. */ + break; + } + } + else + { + /* The previous character was not an escape char. + Check if this is an escape. */ + if (last_was_cr && ch == escape_char) + { + /* It is. Set the flag and continue to next + character. */ + escape_pending = 1; + continue; + } + } + + /* Normal character. Record whether it was a newline, + and append it to the buffer. */ + last_was_cr = (ch == '\r' || ch == '\n'); + buf[0] = ch; + buffer_append(&stdin_buffer, buf, 1); + stdin_bytes += 1; + continue; + } + } + } +} + +void client_process_output(fd_set *writeset) +{ + int len; + char buf[100]; + + /* Write buffered output to stdout. */ + if (FD_ISSET(fileno(stdout), writeset)) + { + /* Write as much data as possible. */ + len = write(fileno(stdout), buffer_ptr(&stdout_buffer), + buffer_len(&stdout_buffer)); + if (len <= 0) + { + if (errno == EAGAIN) + len = 0; + else + { + /* An error or EOF was encountered. Put an error message + to stderr buffer. */ + snprintf(buf, sizeof buf, "write stdout: %.50s\r\n", strerror(errno)); + buffer_append(&stderr_buffer, buf, strlen(buf)); + stderr_bytes += strlen(buf); + quit_pending = 1; + return; + } + } + /* Consume printed data from the buffer. */ + buffer_consume(&stdout_buffer, len); + } + + /* Write buffered output to stderr. */ + if (FD_ISSET(fileno(stderr), writeset)) + { + /* Write as much data as possible. */ + len = write(fileno(stderr), buffer_ptr(&stderr_buffer), + buffer_len(&stderr_buffer)); + if (len <= 0) { + if (errno == EAGAIN) + len = 0; + else + { + /* EOF or error, but can't even print error message. */ + quit_pending = 1; + return; + } + } + /* Consume printed characters from the buffer. */ + buffer_consume(&stderr_buffer, len); + } +} + +/* Implements the interactive session with the server. This is called + after the user has been authenticated, and a command has been + started on the remote host. If escape_char != -1, it is the character + used as an escape character for terminating or suspending the + session. */ + +int client_loop(int have_pty, int escape_char_arg) +{ + double start_time, total_time; + int len; + char buf[100]; + + debug("Entering interactive session."); + + start_time = get_current_time(); + + /* Initialize variables. */ + escape_pending = 0; + last_was_cr = 1; + exit_status = -1; + stdin_eof = 0; + buffer_high = 64 * 1024; + connection_in = packet_get_connection_in(); + connection_out = packet_get_connection_out(); + max_fd = connection_in; + if (connection_out > max_fd) + max_fd = connection_out; + stdin_bytes = 0; + stdout_bytes = 0; + stderr_bytes = 0; + quit_pending = 0; + escape_char = escape_char_arg; + + /* Initialize buffers. */ + buffer_init(&stdin_buffer); + buffer_init(&stdout_buffer); + buffer_init(&stderr_buffer); + + /* Set signal handlers to restore non-blocking mode. */ + signal(SIGINT, signal_handler); + signal(SIGQUIT, signal_handler); + signal(SIGTERM, signal_handler); + signal(SIGPIPE, SIG_IGN); + if (have_pty) + signal(SIGWINCH, window_change_handler); + + /* Enter raw mode if have a pseudo terminal. */ + if (have_pty) + enter_raw_mode(); + + /* Check if we should immediately send of on stdin. */ + client_check_initial_eof_on_stdin(); + + /* Main loop of the client for the interactive session mode. */ + while (!quit_pending) + { + fd_set readset, writeset; + + /* Precess buffered packets sent by the server. */ + client_process_buffered_input_packets(); + + /* Make packets of buffered stdin data, and buffer them for sending + to the server. */ + client_make_packets_from_stdin_data(); + + /* Make packets from buffered channel data, and buffer them for sending + to the server. */ + if (packet_not_very_much_data_to_write()) + channel_output_poll(); + + /* Check if the window size has changed, and buffer a message about + it to the server if so. */ + client_check_window_change(); + + if (quit_pending) + break; + + /* Wait until we have something to do (something becomes available + on one of the descriptors). */ + client_wait_until_can_do_something(&readset, &writeset); + + if (quit_pending) + break; + + /* Do channel operations. */ + channel_after_select(&readset, &writeset); + + /* Process input from the connection and from stdin. Buffer any data + that is available. */ + client_process_input(&readset); + + /* Process output to stdout and stderr. Output to the connection + is processed elsewhere (above). */ + client_process_output(&writeset); + + /* Send as much buffered packet data as possible to the sender. */ + if (FD_ISSET(connection_out, &writeset)) + packet_write_poll(); + } + + /* Terminate the session. */ + + /* Stop watching for window change. */ + if (have_pty) + signal(SIGWINCH, SIG_DFL); + + /* Stop listening for connections. */ + channel_stop_listening(); + + /* In interactive mode (with pseudo tty) display a message indicating that + the connection has been closed. */ + if (have_pty && !quiet_flag) + { + snprintf(buf, sizeof buf, "Connection to %.64s closed.\r\n", host); + buffer_append(&stderr_buffer, buf, strlen(buf)); + stderr_bytes += strlen(buf); + } + + /* Output any buffered data for stdout. */ + while (buffer_len(&stdout_buffer) > 0) + { + len = write(fileno(stdout), buffer_ptr(&stdout_buffer), + buffer_len(&stdout_buffer)); + if (len <= 0) + { + error("Write failed flushing stdout buffer."); + break; + } + buffer_consume(&stdout_buffer, len); + } + + /* Output any buffered data for stderr. */ + while (buffer_len(&stderr_buffer) > 0) + { + len = write(fileno(stderr), buffer_ptr(&stderr_buffer), + buffer_len(&stderr_buffer)); + if (len <= 0) + { + error("Write failed flushing stderr buffer."); + break; + } + buffer_consume(&stderr_buffer, len); + } + + /* Leave raw mode. */ + if (have_pty) + leave_raw_mode(); + + /* Clear and free any buffers. */ + memset(buf, 0, sizeof(buf)); + buffer_free(&stdin_buffer); + buffer_free(&stdout_buffer); + buffer_free(&stderr_buffer); + + /* Report bytes transferred, and transfer rates. */ + total_time = get_current_time() - start_time; + debug("Transferred: stdin %lu, stdout %lu, stderr %lu bytes in %.1f seconds", + stdin_bytes, stdout_bytes, stderr_bytes, total_time); + if (total_time > 0) + debug("Bytes per second: stdin %.1f, stdout %.1f, stderr %.1f", + stdin_bytes / total_time, stdout_bytes / total_time, + stderr_bytes / total_time); + + /* Return the exit status of the program. */ + debug("Exit status %d", exit_status); + return exit_status; +} diff --git a/compat.c b/compat.c new file mode 100644 index 00000000..bf4897e1 --- /dev/null +++ b/compat.c @@ -0,0 +1,10 @@ +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" + +int compat13=0; +void enable_compat13(void){ + log("Enabling compatibility mode for protocol 1.3"); + compat13=1; +} diff --git a/compat.h b/compat.h new file mode 100644 index 00000000..6d6283af --- /dev/null +++ b/compat.h @@ -0,0 +1,7 @@ +/* RCSID("$Id$"); */ + +#ifndef COMPAT_H +#define COMPAT_H +void enable_compat13(void); +extern int compat13; +#endif diff --git a/compress.c b/compress.c new file mode 100644 index 00000000..7ab23e19 --- /dev/null +++ b/compress.c @@ -0,0 +1,160 @@ +/* + +compress.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Oct 25 22:12:46 1995 ylo + +Interface to packet compression for ssh. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include "buffer.h" +#include "zlib.h" + +static z_stream incoming_stream; +static z_stream outgoing_stream; + +/* Initializes compression; level is compression level from 1 to 9 (as in + gzip). */ + +void buffer_compress_init(int level) +{ + debug("Enabling compression at level %d.", level); + if (level < 1 || level > 9) + fatal("Bad compression level %d.", level); + inflateInit(&incoming_stream); + deflateInit(&outgoing_stream, level); +} + +/* Frees any data structures allocated for compression. */ + +void buffer_compress_uninit() +{ + debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f", + outgoing_stream.total_in, outgoing_stream.total_out, + outgoing_stream.total_in == 0 ? 0.0 : + (double)outgoing_stream.total_out / outgoing_stream.total_in); + debug("compress incoming: raw data %lu, compressed %lu, factor %.2f", + incoming_stream.total_out, incoming_stream.total_in, + incoming_stream.total_out == 0 ? 0.0 : + (double)incoming_stream.total_in / incoming_stream.total_out); + inflateEnd(&incoming_stream); + deflateEnd(&outgoing_stream); +} + +/* Compresses the contents of input_buffer into output_buffer. All + packets compressed using this function will form a single + compressed data stream; however, data will be flushed at the end of + every call so that each output_buffer can be decompressed + independently (but in the appropriate order since they together + form a single compression stream) by the receiver. This appends + the compressed data to the output buffer. */ + +void buffer_compress(Buffer *input_buffer, Buffer *output_buffer) +{ + char buf[4096]; + int status; + + /* This case is not handled below. */ + if (buffer_len(input_buffer) == 0) + return; + + /* Input is the contents of the input buffer. */ + outgoing_stream.next_in = buffer_ptr(input_buffer); + outgoing_stream.avail_in = buffer_len(input_buffer); + + /* Loop compressing until deflate() returns with avail_out != 0. */ + do + { + /* Set up fixed-size output buffer. */ + outgoing_stream.next_out = buf; + outgoing_stream.avail_out = sizeof(buf); + + /* Compress as much data into the buffer as possible. */ + status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH); + switch (status) + { + case Z_OK: + /* Append compressed data to output_buffer. */ + buffer_append(output_buffer, buf, + sizeof(buf) - outgoing_stream.avail_out); + break; + case Z_STREAM_END: + fatal("buffer_compress: deflate returned Z_STREAM_END"); + /*NOTREACHED*/ + case Z_STREAM_ERROR: + fatal("buffer_compress: deflate returned Z_STREAM_ERROR"); + /*NOTREACHED*/ + case Z_BUF_ERROR: + fatal("buffer_compress: deflate returned Z_BUF_ERROR"); + /*NOTREACHED*/ + default: + fatal("buffer_compress: deflate returned %d", status); + /*NOTREACHED*/ + } + } + while (outgoing_stream.avail_out == 0); +} + +/* Uncompresses the contents of input_buffer into output_buffer. All + packets uncompressed using this function will form a single + compressed data stream; however, data will be flushed at the end of + every call so that each output_buffer. This must be called for the + same size units that the buffer_compress was called, and in the + same order that buffers compressed with that. This appends the + uncompressed data to the output buffer. */ + +void buffer_uncompress(Buffer *input_buffer, Buffer *output_buffer) +{ + char buf[4096]; + int status; + + incoming_stream.next_in = buffer_ptr(input_buffer); + incoming_stream.avail_in = buffer_len(input_buffer); + + incoming_stream.next_out = buf; + incoming_stream.avail_out = sizeof(buf); + + for (;;) + { + status = inflate(&incoming_stream, Z_PARTIAL_FLUSH); + switch (status) + { + case Z_OK: + buffer_append(output_buffer, buf, + sizeof(buf) - incoming_stream.avail_out); + incoming_stream.next_out = buf; + incoming_stream.avail_out = sizeof(buf); + break; + case Z_STREAM_END: + fatal("buffer_uncompress: inflate returned Z_STREAM_END"); + /*NOTREACHED*/ + case Z_DATA_ERROR: + fatal("buffer_uncompress: inflate returned Z_DATA_ERROR"); + /*NOTREACHED*/ + case Z_STREAM_ERROR: + fatal("buffer_uncompress: inflate returned Z_STREAM_ERROR"); + /*NOTREACHED*/ + case Z_BUF_ERROR: + /* Comments in zlib.h say that we should keep calling inflate() + until we get an error. This appears to be the error that we + get. */ + return; + case Z_MEM_ERROR: + fatal("buffer_uncompress: inflate returned Z_MEM_ERROR"); + /*NOTREACHED*/ + default: + fatal("buffer_uncompress: inflate returned %d", status); + } + } +} + diff --git a/compress.h b/compress.h new file mode 100644 index 00000000..11cfc54d --- /dev/null +++ b/compress.h @@ -0,0 +1,46 @@ +/* + +compress.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Oct 25 22:12:46 1995 ylo + +Interface to packet compression for ssh. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef COMPRESS_H +#define COMPRESS_H + +/* Initializes compression; level is compression level from 1 to 9 (as in + gzip). */ +void buffer_compress_init(int level); + +/* Frees any data structures allocated by buffer_compress_init. */ +void buffer_compress_uninit(); + +/* Compresses the contents of input_buffer into output_buffer. All + packets compressed using this function will form a single + compressed data stream; however, data will be flushed at the end of + every call so that each output_buffer can be decompressed + independently (but in the appropriate order since they together + form a single compression stream) by the receiver. This appends + the compressed data to the output buffer. */ +void buffer_compress(Buffer *input_buffer, Buffer *output_buffer); + +/* Uncompresses the contents of input_buffer into output_buffer. All + packets uncompressed using this function will form a single + compressed data stream; however, data will be flushed at the end of + every call so that each output_buffer. This must be called for the + same size units that the buffer_compress was called, and in the + same order that buffers compressed with that. This appends the + uncompressed data to the output buffer. */ +void buffer_uncompress(Buffer *input_buffer, Buffer *output_buffer); + +#endif /* COMPRESS_H */ diff --git a/crc32.c b/crc32.c new file mode 100644 index 00000000..1d69496a --- /dev/null +++ b/crc32.c @@ -0,0 +1,120 @@ +/* The implementation here was originally done by Gary S. Brown. I have + borrowed the tables directly, and made some minor changes to the + crc32-function (including changing the interface). //ylo */ + +#include "includes.h" +RCSID("$Id$"); + +#include "crc32.h" + + /* ============================================================= */ + /* COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or */ + /* code or tables extracted from it, as desired without restriction. */ + /* */ + /* First, the polynomial itself and its table of feedback terms. The */ + /* polynomial is */ + /* X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0 */ + /* */ + /* Note that we take it "backwards" and put the highest-order term in */ + /* the lowest-order bit. The X^32 term is "implied"; the LSB is the */ + /* X^31 term, etc. The X^0 term (usually shown as "+1") results in */ + /* the MSB being 1. */ + /* */ + /* Note that the usual hardware shift register implementation, which */ + /* is what we're using (we're merely optimizing it by doing eight-bit */ + /* chunks at a time) shifts bits into the lowest-order term. In our */ + /* implementation, that means shifting towards the right. Why do we */ + /* do it this way? Because the calculated CRC must be transmitted in */ + /* order from highest-order term to lowest-order term. UARTs transmit */ + /* characters in order from LSB to MSB. By storing the CRC this way, */ + /* we hand it to the UART in the order low-byte to high-byte; the UART */ + /* sends each low-bit to hight-bit; and the result is transmission bit */ + /* by bit from highest- to lowest-order term without requiring any bit */ + /* shuffling on our part. Reception works similarly. */ + /* */ + /* The feedback terms table consists of 256, 32-bit entries. Notes: */ + /* */ + /* The table can be generated at runtime if desired; code to do so */ + /* is shown later. It might not be obvious, but the feedback */ + /* terms simply represent the results of eight shift/xor opera- */ + /* tions for all combinations of data and CRC register values. */ + /* */ + /* The values must be right-shifted by eight bits by the "updcrc" */ + /* logic; the shift must be unsigned (bring in zeroes). On some */ + /* hardware you could probably optimize the shift in assembler by */ + /* using byte-swap instructions. */ + /* polynomial $edb88320 */ + /* */ + /* -------------------------------------------------------------------- */ + +static unsigned int crc32_tab[] = { + 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L, + 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L, + 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L, + 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL, + 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L, + 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L, + 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L, + 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL, + 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L, + 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL, + 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, + 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L, + 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L, + 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL, + 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL, + 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L, + 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL, + 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L, + 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L, + 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L, + 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL, + 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L, + 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L, + 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL, + 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L, + 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L, + 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L, + 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L, + 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L, + 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL, + 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL, + 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L, + 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L, + 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL, + 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL, + 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L, + 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL, + 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L, + 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL, + 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L, + 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL, + 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L, + 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L, + 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL, + 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L, + 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L, + 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, + 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L, + 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L, + 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L, + 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL, + 0x2d02ef8dL + }; + +/* Return a 32-bit CRC of the contents of the buffer. */ + +unsigned int crc32(const unsigned char *s, unsigned int len) +{ + unsigned int i; + unsigned int crc32val; + + crc32val = 0; + for (i = 0; i < len; i ++) + { + crc32val = + crc32_tab[(crc32val ^ s[i]) & 0xff] ^ + (crc32val >> 8); + } + return crc32val; +} diff --git a/crc32.h b/crc32.h new file mode 100644 index 00000000..80bcf6ee --- /dev/null +++ b/crc32.h @@ -0,0 +1,25 @@ +/* + +crc32.h + +Author: Tatu Ylonen + +Copyright (c) 1992 Tatu Ylonen, Espoo, Finland + All rights reserved + +Created: Tue Feb 11 14:37:27 1992 ylo + +Functions for computing 32-bit CRC. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef CRC32_H +#define CRC32_H + +/* This computes a 32 bit CRC of the data in the buffer, and returns the + CRC. The polynomial used is 0xedb88320. */ +unsigned int crc32(const unsigned char *buf, unsigned int len); + +#endif /* CRC32_H */ diff --git a/deattack.c b/deattack.c new file mode 100644 index 00000000..76e5613f --- /dev/null +++ b/deattack.c @@ -0,0 +1,180 @@ +/* + * $Id$ + * Cryptographic attack detector for ssh - source code + * + * Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina. + * + * All rights reserved. Redistribution and use in source and binary + * forms, with or without modification, are permitted provided that + * this copyright notice is retained. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES ARE DISCLAIMED. IN NO EVENT SHALL CORE SDI S.A. BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY OR + * CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OR MISUSE OF THIS + * SOFTWARE. + * + * Ariel Futoransky + * */ + +#include "includes.h" +#include "deattack.h" +#include "ssh.h" +#include "crc32.h" +#include "getput.h" +#include "xmalloc.h" + +/* SSH Constants */ +#define SSH_MAXBLOCKS (32 * 1024) +#define SSH_BLOCKSIZE (8) + +/* Hashing constants */ +#define HASH_MINSIZE (8 * 1024) +#define HASH_ENTRYSIZE (2) +#define HASH_FACTOR(x) ((x)*3/2) +#define HASH_UNUSEDCHAR (0xff) +#define HASH_UNUSED (0xffff) +#define HASH_IV (0xfffe) + +#define HASH_MINBLOCKS (7*SSH_BLOCKSIZE) + + +/* Hash function (Input keys are cipher results) */ +#define HASH(x) GET_32BIT(x) + +#define CMP(a,b) (memcmp(a, b, SSH_BLOCKSIZE)) + + +void +crc_update(u_int32_t * a, u_int32_t b) +{ + b ^= *a; + *a = crc32((unsigned char *) &b, sizeof(b)); +} + +/* + check_crc + detects if a block is used in a particular pattern + */ + +int +check_crc(unsigned char *S, unsigned char *buf, u_int32_t len, unsigned char *IV) +{ + u_int32_t crc; + unsigned char *c; + + crc = 0; + if (IV && !CMP(S, IV)) + { + crc_update(&crc, 1); + crc_update(&crc, 0); + } + for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) + { + if (!CMP(S, c)) + { + crc_update(&crc, 1); + crc_update(&crc, 0); + } else + { + crc_update(&crc, 0); + crc_update(&crc, 0); + } + } + + return (crc == 0); +} + + +/* + detect_attack + Detects a crc32 compensation attack on a packet + */ +int +detect_attack(unsigned char *buf, u_int32_t len, unsigned char *IV) +{ + static u_int16_t *h = (u_int16_t *) NULL; + static u_int16_t n = HASH_MINSIZE / HASH_ENTRYSIZE; + register u_int32_t i, j; + u_int32_t l; + register unsigned char *c; + unsigned char *d; + + + assert(len <= (SSH_MAXBLOCKS * SSH_BLOCKSIZE)); + assert(len % SSH_BLOCKSIZE == 0); + + for (l = n; l < HASH_FACTOR(len / SSH_BLOCKSIZE); l = l << 2); + + if (h == NULL) + { + debug("Installing crc compensation attack detector."); + n = l; + h = (u_int16_t *) xmalloc(n * HASH_ENTRYSIZE); + } else + { + if (l > n) + { + n = l; + h = (u_int16_t *) xrealloc(h, n * HASH_ENTRYSIZE); + } + } + + + if (len <= HASH_MINBLOCKS) + { + for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) + { + if (IV && (!CMP(c, IV))) + { + if ((check_crc(c, buf, len, IV))) + return (DEATTACK_DETECTED); + else + break; + } + for (d = buf; d < c; d += SSH_BLOCKSIZE) + { + if (!CMP(c, d)) + { + if ((check_crc(c, buf, len, IV))) + return (DEATTACK_DETECTED); + else + break; + } + } + } + return (DEATTACK_OK); + } + memset(h, HASH_UNUSEDCHAR, n * HASH_ENTRYSIZE); + + if (IV) + h[HASH(IV) & (n - 1)] = HASH_IV; + + + for (c = buf, j = 0; c < (buf + len); c += SSH_BLOCKSIZE, j++) + { + for (i = HASH(c) & (n - 1); h[i] != HASH_UNUSED; + i = (i + 1) & (n - 1)) + { + if (h[i] == HASH_IV) + { + if (!CMP(c, IV)) + { + if (check_crc(c, buf, len, IV)) + return (DEATTACK_DETECTED); + else + break; + } + } else if (!CMP(c, buf + h[i] * SSH_BLOCKSIZE)) + { + if (check_crc(c, buf, len, IV)) + return (DEATTACK_DETECTED); + else + break; + } + } + h[i] = j; + } + + return (DEATTACK_OK); +} diff --git a/deattack.h b/deattack.h new file mode 100644 index 00000000..c04b56b5 --- /dev/null +++ b/deattack.h @@ -0,0 +1,27 @@ +/* $Id$ + * Cryptographic attack detector for ssh - Header file + * + * Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina. + * + * All rights reserved. Redistribution and use in source and binary + * forms, with or without modification, are permitted provided that + * this copyright notice is retained. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES ARE DISCLAIMED. IN NO EVENT SHALL CORE SDI S.A. BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY OR + * CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OR MISUSE OF THIS + * SOFTWARE. + * + * Ariel Futoransky + * */ + +#ifndef _DEATTACK_H +#define _DEATTACK_H + +/* Return codes */ +#define DEATTACK_OK 0 +#define DEATTACK_DETECTED 1 + +int detect_attack(unsigned char *buf, u_int32_t len, unsigned char IV[8]); +#endif diff --git a/getput.h b/getput.h new file mode 100644 index 00000000..38b7d88f --- /dev/null +++ b/getput.h @@ -0,0 +1,64 @@ +/* + +getput.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Jun 28 22:36:30 1995 ylo + +Macros for storing and retrieving data in msb first and lsb first order. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef GETPUT_H +#define GETPUT_H + +/*------------ macros for storing/extracting msb first words -------------*/ + +#define GET_32BIT(cp) (((unsigned long)(unsigned char)(cp)[0] << 24) | \ + ((unsigned long)(unsigned char)(cp)[1] << 16) | \ + ((unsigned long)(unsigned char)(cp)[2] << 8) | \ + ((unsigned long)(unsigned char)(cp)[3])) + +#define GET_16BIT(cp) (((unsigned long)(unsigned char)(cp)[0] << 8) | \ + ((unsigned long)(unsigned char)(cp)[1])) + +#define PUT_32BIT(cp, value) do { \ + (cp)[0] = (value) >> 24; \ + (cp)[1] = (value) >> 16; \ + (cp)[2] = (value) >> 8; \ + (cp)[3] = (value); } while (0) + +#define PUT_16BIT(cp, value) do { \ + (cp)[0] = (value) >> 8; \ + (cp)[1] = (value); } while (0) + +/*------------ macros for storing/extracting lsb first words -------------*/ + +#define GET_32BIT_LSB_FIRST(cp) \ + (((unsigned long)(unsigned char)(cp)[0]) | \ + ((unsigned long)(unsigned char)(cp)[1] << 8) | \ + ((unsigned long)(unsigned char)(cp)[2] << 16) | \ + ((unsigned long)(unsigned char)(cp)[3] << 24)) + +#define GET_16BIT_LSB_FIRST(cp) \ + (((unsigned long)(unsigned char)(cp)[0]) | \ + ((unsigned long)(unsigned char)(cp)[1] << 8)) + +#define PUT_32BIT_LSB_FIRST(cp, value) do { \ + (cp)[0] = (value); \ + (cp)[1] = (value) >> 8; \ + (cp)[2] = (value) >> 16; \ + (cp)[3] = (value) >> 24; } while (0) + +#define PUT_16BIT_LSB_FIRST(cp, value) do { \ + (cp)[0] = (value); \ + (cp)[1] = (value) >> 8; } while (0) + +#endif /* GETPUT_H */ + diff --git a/helper.c b/helper.c new file mode 100644 index 00000000..3b0402ec --- /dev/null +++ b/helper.c @@ -0,0 +1,108 @@ +/* +** +** OpenBSD emulation routines +** +** Damien Miller +** +** Copyright 1999 Internet Business Solutions +** +** Permission is hereby granted, free of charge, to any person +** obtaining a copy of this software and associated documentation +** files (the "Software"), to deal in the Software without +** restriction, including without limitation the rights to use, copy, +** modify, merge, publish, distribute, sublicense, and/or sell copies +** of the Software, and to permit persons to whom the Software is +** furnished to do so, subject to the following conditions: +** +** The above copyright notice and this permission notice shall be +** included in all copies or substantial portions of the Software. +** +** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY +** KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE +** WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE +** AND NONINFRINGEMENT. IN NO EVENT SHALL DAMIEN MILLER OR INTERNET +** BUSINESS SOLUTIONS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, +** ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE +** OR OTHER DEALINGS IN THE SOFTWARE. +** +** Except as contained in this notice, the name of Internet Business +** Solutions shall not be used in advertising or otherwise to promote +** the sale, use or other dealings in this Software without prior +** written authorization from Internet Business Solutions. +** +*/ + +#include +#include +#include +#include +#include + +#include +#include +#include + +#include "rc4.h" +#include "xmalloc.h" + +#include "helper.h" + +void get_random_bytes(unsigned char *buf, int len); + +static rc4_t *rc4 = NULL; + +void setproctitle(const char *fmt, ...) +{ + /* FIXME */ +} + +unsigned char arc4random(void) +{ + unsigned char r; + + if (rc4 == NULL) + arc4random_stir(); + + rc4_getbytes(rc4, &r, 1); + + return(r); +} + +void arc4random_stir(void) +{ + unsigned char rand_buf[32]; + + if (rc4 == NULL) + rc4 = xmalloc(sizeof(*rc4)); + + get_random_bytes(rand_buf, sizeof(rand_buf)); + rc4_key(rc4, rand_buf, sizeof(rand_buf)); +} + +void get_random_bytes(unsigned char *buf, int len) +{ + int urandom; + int c; + + urandom = open("/dev/urandom", O_RDONLY); + if (urandom == -1) + { + fprintf(stderr, "Couldn't open /dev/urandom: %s", strerror(errno)); + exit(1); + } + + c = read(urandom, buf, len); + if (c == -1) + { + fprintf(stderr, "Couldn't read from /dev/urandom: %s", strerror(errno)); + exit(1); + } + + if (c != len) + { + fprintf(stderr, "Short read from /dev/urandom"); + exit(1); + } +} + diff --git a/helper.h b/helper.h new file mode 100644 index 00000000..2f09daa8 --- /dev/null +++ b/helper.h @@ -0,0 +1,43 @@ +/* +** +** OpenBSD emulation routines +** +** Damien Miller +** +** Copyright 1999 Internet Business Solutions +** +** Permission is hereby granted, free of charge, to any person +** obtaining a copy of this software and associated documentation +** files (the "Software"), to deal in the Software without +** restriction, including without limitation the rights to use, copy, +** modify, merge, publish, distribute, sublicense, and/or sell copies +** of the Software, and to permit persons to whom the Software is +** furnished to do so, subject to the following conditions: +** +** The above copyright notice and this permission notice shall be +** included in all copies or substantial portions of the Software. +** +** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY +** KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE +** WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE +** AND NONINFRINGEMENT. IN NO EVENT SHALL DAMIEN MILLER OR INTERNET +** BUSINESS SOLUTIONS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, +** ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE +** OR OTHER DEALINGS IN THE SOFTWARE. +** +** Except as contained in this notice, the name of Internet Business +** Solutions shall not be used in advertising or otherwise to promote +** the sale, use or other dealings in this Software without prior +** written authorization from Internet Business Solutions. +** +*/ + +#ifndef _HELPER_H +#define _HELPER_H + +unsigned char arc4random(void); +void arc4random_stir(void); +void setproctitle(const char *fmt, ...); + +#endif /* _HELPER_H */ diff --git a/hostfile.c b/hostfile.c new file mode 100644 index 00000000..0566585a --- /dev/null +++ b/hostfile.c @@ -0,0 +1,279 @@ +/* + +hostfile.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Thu Jun 29 07:10:56 1995 ylo + +Functions for manipulating the known hosts files. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "packet.h" +#include "ssh.h" + +/* Reads a multiple-precision integer in hex from the buffer, and advances the + pointer. The integer must already be initialized. This function is + permitted to modify the buffer. This leaves *cpp to point just beyond + the last processed (and maybe modified) character. Note that this may + modify the buffer containing the number. */ + +int +auth_rsa_read_bignum(char **cpp, BIGNUM *value) +{ + char *cp = *cpp; + int len, old; + + /* Skip any leading whitespace. */ + for (; *cp == ' ' || *cp == '\t'; cp++) + ; + + /* Check that it begins with a hex digit. */ + if (*cp < '0' || *cp > '9') + return 0; + + /* Save starting position. */ + *cpp = cp; + + /* Move forward until all hex digits skipped. */ + for (; *cp >= '0' && *cp <= '9'; cp++) + ; + + /* Compute the length of the hex number. */ + len = cp - *cpp; + + /* Save the old terminating character, and replace it by \0. */ + old = *cp; + *cp = 0; + + + /* Parse the number. */ + if (BN_dec2bn(&value, *cpp) == 0) + return 0; + + /* Restore old terminating character. */ + *cp = old; + + /* Move beyond the number and return success. */ + *cpp = cp; + return 1; +} + +/* Parses an RSA key (number of bits, e, n) from a string. Moves the pointer + over the key. Skips any whitespace at the beginning and at end. */ + +int +auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM *e, BIGNUM *n) +{ + unsigned int bits; + char *cp; + + /* Skip leading whitespace. */ + for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) + ; + + /* Get number of bits. */ + if (*cp < '0' || *cp > '9') + return 0; /* Bad bit count... */ + for (bits = 0; *cp >= '0' && *cp <= '9'; cp++) + bits = 10 * bits + *cp - '0'; + + /* Get public exponent. */ + if (!auth_rsa_read_bignum(&cp, e)) + return 0; + + /* Get public modulus. */ + if (!auth_rsa_read_bignum(&cp, n)) + return 0; + + /* Skip trailing whitespace. */ + for (; *cp == ' ' || *cp == '\t'; cp++) + ; + + /* Return results. */ + *cpp = cp; + *bitsp = bits; + return 1; +} + +/* Tries to match the host name (which must be in all lowercase) against the + comma-separated sequence of subpatterns (each possibly preceded by ! to + indicate negation). Returns true if there is a positive match; zero + otherwise. */ + +int +match_hostname(const char *host, const char *pattern, unsigned int len) +{ + char sub[1024]; + int negated; + int got_positive; + unsigned int i, subi; + + got_positive = 0; + for (i = 0; i < len;) + { + /* Check if the subpattern is negated. */ + if (pattern[i] == '!') + { + negated = 1; + i++; + } + else + negated = 0; + + /* Extract the subpattern up to a comma or end. Convert the subpattern + to lowercase. */ + for (subi = 0; + i < len && subi < sizeof(sub) - 1 && pattern[i] != ','; + subi++, i++) + sub[subi] = isupper(pattern[i]) ? tolower(pattern[i]) : pattern[i]; + /* If subpattern too long, return failure (no match). */ + if (subi >= sizeof(sub) - 1) + return 0; + + /* If the subpattern was terminated by a comma, skip the comma. */ + if (i < len && pattern[i] == ',') + i++; + + /* Null-terminate the subpattern. */ + sub[subi] = '\0'; + + /* Try to match the subpattern against the host name. */ + if (match_pattern(host, sub)) { + if (negated) + return 0; /* Fail if host matches any negated subpattern. */ + else + got_positive = 1; + } + } + + /* Return success if got a positive match. If there was a negative match, + we have already returned zero and never get here. */ + return got_positive; +} + +/* Checks whether the given host (which must be in all lowercase) is + already in the list of our known hosts. + Returns HOST_OK if the host is known and has the specified key, + HOST_NEW if the host is not known, and HOST_CHANGED if the host is known + but used to have a different host key. */ + +HostStatus +check_host_in_hostfile(const char *filename, + const char *host, unsigned int bits, + BIGNUM *e, BIGNUM *n, + BIGNUM *ke, BIGNUM *kn) +{ + FILE *f; + char line[8192]; + unsigned int kbits, hostlen; + char *cp, *cp2; + HostStatus end_return; + struct stat st; + + /* Open the file containing the list of known hosts. */ + f = fopen(filename, "r"); + if (!f) + { + if (stat(filename, &st) >= 0) + { + packet_send_debug("Could not open %.900s for reading.", filename); + packet_send_debug("If your home directory is on an NFS volume, it may need to be world-readable."); + } + return HOST_NEW; + } + + /* Cache the length of the host name. */ + hostlen = strlen(host); + + /* Return value when the loop terminates. This is set to HOST_CHANGED if + we have seen a different key for the host and have not found the proper + one. */ + end_return = HOST_NEW; + + /* Go trough the file. */ + while (fgets(line, sizeof(line), f)) + { + cp = line; + + /* Skip any leading whitespace. */ + for (; *cp == ' ' || *cp == '\t'; cp++) + ; + + /* Ignore comment lines and empty lines. */ + if (!*cp || *cp == '#' || *cp == '\n') + continue; + + /* Find the end of the host name portion. */ + for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) + ; + + /* Check if the host name matches. */ + if (!match_hostname(host, cp, (unsigned int)(cp2 - cp))) + continue; + + /* Got a match. Skip host name. */ + cp = cp2; + + /* Extract the key from the line. This will skip any leading + whitespace. Ignore badly formatted lines. */ + if (!auth_rsa_read_key(&cp, &kbits, ke, kn)) + continue; + + /* Check if the current key is the same as the previous one. */ + if (kbits == bits && BN_cmp(ke, e) == 0 && BN_cmp(kn, n) == 0) + { + /* Ok, they match. */ + fclose(f); + return HOST_OK; + } + + /* They do not match. We will continue to go through the file; however, + we note that we will not return that it is new. */ + end_return = HOST_CHANGED; + } + /* Clear variables and close the file. */ + fclose(f); + + /* Return either HOST_NEW or HOST_CHANGED, depending on whether we saw a + different key for the host. */ + return end_return; +} + +/* Appends an entry to the host file. Returns false if the entry + could not be appended. */ + +int +add_host_to_hostfile(const char *filename, const char *host, + unsigned int bits, BIGNUM *e, BIGNUM *n) +{ + FILE *f; + char *buf; + + /* Open the file for appending. */ + f = fopen(filename, "a"); + if (!f) + return 0; + + /* Print the host name and key to the file. */ + fprintf(f, "%s %u ", host, bits); + buf = BN_bn2dec(e); + assert(buf != NULL); + fprintf(f, "%s ", buf); + free (buf); + buf = BN_bn2dec(n); + assert(buf != NULL); + fprintf(f, "%s\n", buf); + free (buf); + + /* Close the file. */ + fclose(f); + return 1; +} diff --git a/includes.h b/includes.h new file mode 100644 index 00000000..862dbd64 --- /dev/null +++ b/includes.h @@ -0,0 +1,78 @@ +/* + +includes.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Thu Mar 23 16:29:37 1995 ylo + +This file includes most of the needed system headers. + +*/ + +#ifndef INCLUDES_H +#define INCLUDES_H + +#define RCSID(msg) \ +static /**/const char *const rcsid[] = { (char *)rcsid, "\100(#)" msg } + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "version.h" + +#include "helper.h" +#include "mktemp.h" +#include "strlcpy.h" + +/* Define this to be the path of the xauth program. */ +#ifndef XAUTH_PATH +#define XAUTH_PATH "/usr/X11R6/bin/xauth" +#endif /* XAUTH_PATH */ + +/* Define this to be the path of the rsh program. */ +#ifndef _PATH_RSH +#define _PATH_RSH "/usr/bin/rsh" +#endif /* _PATH_RSH */ + +/* Define this to use pipes instead of socketpairs for communicating with the + client program. Socketpairs do not seem to work on all systems. */ +#define USE_PIPES 1 + +#endif /* INCLUDES_H */ diff --git a/log-client.c b/log-client.c new file mode 100644 index 00000000..1e2be077 --- /dev/null +++ b/log-client.c @@ -0,0 +1,138 @@ +/* + +log-client.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Mon Mar 20 21:13:40 1995 ylo + +Client-side versions of debug(), log(), etc. These print to stderr. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "xmalloc.h" +#include "ssh.h" + +static int log_debug = 0; +static int log_quiet = 0; + +void log_init(char *av0, int on_stderr, int debug, int quiet, + SyslogFacility facility) +{ + log_debug = debug; + log_quiet = quiet; +} + +void log(const char *fmt, ...) +{ + va_list args; + + if (log_quiet) + return; + va_start(args, fmt); + vfprintf(stderr, fmt, args); + fprintf(stderr, "\r\n"); + va_end(args); +} + +void debug(const char *fmt, ...) +{ + va_list args; + if (log_quiet || !log_debug) + return; + va_start(args, fmt); + fprintf(stderr, "debug: "); + vfprintf(stderr, fmt, args); + fprintf(stderr, "\r\n"); + va_end(args); +} + +void error(const char *fmt, ...) +{ + va_list args; + if (log_quiet) + return; + va_start(args, fmt); + vfprintf(stderr, fmt, args); + fprintf(stderr, "\r\n"); + va_end(args); +} + +struct fatal_cleanup +{ + struct fatal_cleanup *next; + void (*proc)(void *); + void *context; +}; + +static struct fatal_cleanup *fatal_cleanups = NULL; + +/* Registers a cleanup function to be called by fatal() before exiting. */ + +void fatal_add_cleanup(void (*proc)(void *), void *context) +{ + struct fatal_cleanup *cu; + + cu = xmalloc(sizeof(*cu)); + cu->proc = proc; + cu->context = context; + cu->next = fatal_cleanups; + fatal_cleanups = cu; +} + +/* Removes a cleanup frunction to be called at fatal(). */ + +void fatal_remove_cleanup(void (*proc)(void *context), void *context) +{ + struct fatal_cleanup **cup, *cu; + + for (cup = &fatal_cleanups; *cup; cup = &cu->next) + { + cu = *cup; + if (cu->proc == proc && cu->context == context) + { + *cup = cu->next; + xfree(cu); + return; + } + } + fatal("fatal_remove_cleanup: no such cleanup function: 0x%lx 0x%lx\n", + (unsigned long)proc, (unsigned long)context); +} + +/* Function to display an error message and exit. This is in this file because + this needs to restore terminal modes before exiting. See log-client.c + for other related functions. */ + +void fatal(const char *fmt, ...) +{ + va_list args; + struct fatal_cleanup *cu, *next_cu; + static int fatal_called = 0; + + if (!fatal_called) + { + fatal_called = 1; + + /* Call cleanup functions. */ + for (cu = fatal_cleanups; cu; cu = next_cu) + { + next_cu = cu->next; + (*cu->proc)(cu->context); + } + } + + va_start(args, fmt); + vfprintf(stderr, fmt, args); + fprintf(stderr, "\r\n"); + va_end(args); + exit(255); +} + +/* fatal() is in ssh.c so that it can properly reset terminal modes. */ diff --git a/log-server.c b/log-server.c new file mode 100644 index 00000000..b2bef645 --- /dev/null +++ b/log-server.c @@ -0,0 +1,233 @@ +/* + +log-server.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Mon Mar 20 21:19:30 1995 ylo + +Server-side versions of debug(), log(), etc. These normally send the output +to the system log. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include +#include "packet.h" +#include "xmalloc.h" +#include "ssh.h" + +static int log_debug = 0; +static int log_quiet = 0; +static int log_on_stderr = 0; + +/* Initialize the log. + av0 program name (should be argv[0]) + on_stderr print also on stderr + debug send debugging messages to system log + quiet don\'t log anything + */ + +void log_init(char *av0, int on_stderr, int debug, int quiet, + SyslogFacility facility) +{ + int log_facility; + + switch (facility) + { + case SYSLOG_FACILITY_DAEMON: + log_facility = LOG_DAEMON; + break; + case SYSLOG_FACILITY_USER: + log_facility = LOG_USER; + break; + case SYSLOG_FACILITY_AUTH: + log_facility = LOG_AUTH; + break; + case SYSLOG_FACILITY_LOCAL0: + log_facility = LOG_LOCAL0; + break; + case SYSLOG_FACILITY_LOCAL1: + log_facility = LOG_LOCAL1; + break; + case SYSLOG_FACILITY_LOCAL2: + log_facility = LOG_LOCAL2; + break; + case SYSLOG_FACILITY_LOCAL3: + log_facility = LOG_LOCAL3; + break; + case SYSLOG_FACILITY_LOCAL4: + log_facility = LOG_LOCAL4; + break; + case SYSLOG_FACILITY_LOCAL5: + log_facility = LOG_LOCAL5; + break; + case SYSLOG_FACILITY_LOCAL6: + log_facility = LOG_LOCAL6; + break; + case SYSLOG_FACILITY_LOCAL7: + log_facility = LOG_LOCAL7; + break; + default: + fprintf(stderr, "Unrecognized internal syslog facility code %d\n", + (int)facility); + exit(1); + } + + log_debug = debug; + log_quiet = quiet; + log_on_stderr = on_stderr; + closelog(); /* Close any previous log. */ + openlog(av0, LOG_PID, log_facility); +} + +#define MSGBUFSIZE 1024 + +#define DECL_MSGBUF char msgbuf[MSGBUFSIZE] + +/* Log this message (information that usually should go to the log). */ + +void log(const char *fmt, ...) +{ + va_list args; + DECL_MSGBUF; + if (log_quiet) + return; + va_start(args, fmt); + vsnprintf(msgbuf, MSGBUFSIZE, fmt, args); + va_end(args); + if (log_on_stderr) + fprintf(stderr, "log: %s\n", msgbuf); + syslog(LOG_INFO, "log: %.500s", msgbuf); +} + +/* Debugging messages that should not be logged during normal operation. */ + +void debug(const char *fmt, ...) +{ + va_list args; + DECL_MSGBUF; + if (!log_debug || log_quiet) + return; + va_start(args, fmt); + vsnprintf(msgbuf, MSGBUFSIZE, fmt, args); + va_end(args); + if (log_on_stderr) + fprintf(stderr, "debug: %s\n", msgbuf); + syslog(LOG_DEBUG, "debug: %.500s", msgbuf); +} + +/* Error messages that should be logged. */ + +void error(const char *fmt, ...) +{ + va_list args; + DECL_MSGBUF; + if (log_quiet) + return; + va_start(args, fmt); + vsnprintf(msgbuf, MSGBUFSIZE, fmt, args); + va_end(args); + if (log_on_stderr) + fprintf(stderr, "error: %s\n", msgbuf); + syslog(LOG_ERR, "error: %.500s", msgbuf); +} + +struct fatal_cleanup +{ + struct fatal_cleanup *next; + void (*proc)(void *); + void *context; +}; + +static struct fatal_cleanup *fatal_cleanups = NULL; + +/* Registers a cleanup function to be called by fatal() before exiting. */ + +void fatal_add_cleanup(void (*proc)(void *), void *context) +{ + struct fatal_cleanup *cu; + + cu = xmalloc(sizeof(*cu)); + cu->proc = proc; + cu->context = context; + cu->next = fatal_cleanups; + fatal_cleanups = cu; +} + +/* Removes a cleanup frunction to be called at fatal(). */ + +void fatal_remove_cleanup(void (*proc)(void *context), void *context) +{ + struct fatal_cleanup **cup, *cu; + + for (cup = &fatal_cleanups; *cup; cup = &cu->next) + { + cu = *cup; + if (cu->proc == proc && cu->context == context) + { + *cup = cu->next; + xfree(cu); + return; + } + } + fatal("fatal_remove_cleanup: no such cleanup function: 0x%lx 0x%lx\n", + (unsigned long)proc, (unsigned long)context); +} + +/* Fatal messages. This function never returns. */ + +void fatal(const char *fmt, ...) +{ + va_list args; + struct fatal_cleanup *cu, *next_cu; + static int fatal_called = 0; +#if defined(KRB4) + extern char *ticket; +#endif /* KRB4 */ + DECL_MSGBUF; + + if (log_quiet) + exit(1); + va_start(args, fmt); + vsnprintf(msgbuf, MSGBUFSIZE, fmt, args); + va_end(args); + if (log_on_stderr) + fprintf(stderr, "fatal: %s\n", msgbuf); + syslog(LOG_ERR, "fatal: %.500s", msgbuf); + + if (fatal_called) + exit(1); + fatal_called = 1; + + /* Call cleanup functions. */ + for (cu = fatal_cleanups; cu; cu = next_cu) + { + next_cu = cu->next; + debug("Calling cleanup 0x%lx(0x%lx)", + (unsigned long)cu->proc, (unsigned long)cu->context); + (*cu->proc)(cu->context); + } +#if defined(KRB4) + /* If you forwarded a ticket you get one shot for proper + authentication. */ + /* If tgt was passed unlink file */ + if (ticket) + { + if (strcmp(ticket,"none")) + unlink(ticket); + else + ticket = NULL; + } +#endif /* KRB4 */ + + /* If local XAUTHORITY was created, remove it. */ + if (xauthfile) unlink(xauthfile); + + exit(1); +} diff --git a/login.c b/login.c new file mode 100644 index 00000000..aa6db16e --- /dev/null +++ b/login.c @@ -0,0 +1,118 @@ +/* + +login.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Fri Mar 24 14:51:08 1995 ylo + +This file performs some of the things login(1) normally does. We cannot +easily use something like login -p -h host -f user, because there are +several different logins around, and it is hard to determined what kind of +login the current system has. Also, we want to be able to execute commands +on a tty. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include +#include "ssh.h" + +/* Returns the time when the user last logged in. Returns 0 if the + information is not available. This must be called before record_login. + The host the user logged in from will be returned in buf. */ + +/* Returns the time when the user last logged in (or 0 if no previous login + is found). The name of the host used last time is returned in buf. */ + +unsigned long get_last_login_time(uid_t uid, const char *logname, + char *buf, unsigned int bufsize) +{ + struct lastlog ll; + char *lastlog; + int fd; + + lastlog = _PATH_LASTLOG; + + buf[0] = '\0'; + + fd = open(lastlog, O_RDONLY); + if (fd < 0) + return 0; + lseek(fd, (off_t)((long)uid * sizeof(ll)), SEEK_SET); + if (read(fd, &ll, sizeof(ll)) != sizeof(ll)) + { + close(fd); + return 0; + } + close(fd); + if (bufsize > sizeof(ll.ll_host) + 1) + bufsize = sizeof(ll.ll_host) + 1; + strncpy(buf, ll.ll_host, bufsize - 1); + buf[bufsize - 1] = 0; + return ll.ll_time; +} + +/* Records that the user has logged in. I these parts of operating systems + were more standardized. */ + +void record_login(int pid, const char *ttyname, const char *user, uid_t uid, + const char *host, struct sockaddr_in *addr) +{ + int fd; + struct lastlog ll; + char *lastlog; + + struct utmp u; + const char *utmp, *wtmp; + + /* Construct an utmp/wtmp entry. */ + memset(&u, 0, sizeof(u)); + strncpy(u.ut_line, ttyname + 5, sizeof(u.ut_line)); + u.ut_time = time(NULL); + strncpy(u.ut_name, user, sizeof(u.ut_name)); + strncpy(u.ut_host, host, sizeof(u.ut_host)); + + /* Figure out the file names. */ + utmp = _PATH_UTMP; + wtmp = _PATH_WTMP; + + login(&u); + + lastlog = _PATH_LASTLOG; + + /* Update lastlog unless actually recording a logout. */ + if (strcmp(user, "") != 0) + { + /* It is safer to bzero the lastlog structure first because some + systems might have some extra fields in it (e.g. SGI) */ + memset(&ll, 0, sizeof(ll)); + + /* Update lastlog. */ + ll.ll_time = time(NULL); + strncpy(ll.ll_line, ttyname + 5, sizeof(ll.ll_line)); + strncpy(ll.ll_host, host, sizeof(ll.ll_host)); + fd = open(lastlog, O_RDWR); + if (fd >= 0) + { + lseek(fd, (off_t)((long)uid * sizeof(ll)), SEEK_SET); + if (write(fd, &ll, sizeof(ll)) != sizeof(ll)) + log("Could not write %.100s: %.100s", lastlog, strerror(errno)); + close(fd); + } + } +} + +/* Records that the user has logged out. */ + +void record_logout(int pid, const char *ttyname) +{ + const char *line = ttyname + 5; /* /dev/ttyq8 -> ttyq8 */ + if (logout(line)) + logwtmp(line, "", ""); +} diff --git a/match.c b/match.c new file mode 100644 index 00000000..b8ceea9f --- /dev/null +++ b/match.c @@ -0,0 +1,78 @@ +/* + +match.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Thu Jun 22 01:17:50 1995 ylo + +Simple pattern matching, with '*' and '?' as wildcards. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" + +/* Returns true if the given string matches the pattern (which may contain + ? and * as wildcards), and zero if it does not match. */ + +int match_pattern(const char *s, const char *pattern) +{ + while (1) + { + /* If at end of pattern, accept if also at end of string. */ + if (!*pattern) + return !*s; + + /* Process '*'. */ + if (*pattern == '*') + { + /* Skip the asterisk. */ + pattern++; + + /* If at end of pattern, accept immediately. */ + if (!*pattern) + return 1; + + /* If next character in pattern is known, optimize. */ + if (*pattern != '?' && *pattern != '*') + { + /* Look instances of the next character in pattern, and try + to match starting from those. */ + for (; *s; s++) + if (*s == *pattern && + match_pattern(s + 1, pattern + 1)) + return 1; + /* Failed. */ + return 0; + } + + /* Move ahead one character at a time and try to match at each + position. */ + for (; *s; s++) + if (match_pattern(s, pattern)) + return 1; + /* Failed. */ + return 0; + } + + /* There must be at least one more character in the string. If we are + at the end, fail. */ + if (!*s) + return 0; + + /* Check if the next character of the string is acceptable. */ + if (*pattern != '?' && *pattern != *s) + return 0; + + /* Move to the next character, both in string and in pattern. */ + s++; + pattern++; + } + /*NOTREACHED*/ +} diff --git a/mktemp.c b/mktemp.c new file mode 100644 index 00000000..919c5317 --- /dev/null +++ b/mktemp.c @@ -0,0 +1,181 @@ +/* THIS FILE HAS BEEN MODIFIED FROM THE ORIGINAL OPENBSD SOURCE */ +/* Changes: Removed mktemp */ + +/* + * Copyright (c) 1987, 1993 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#if defined(LIBC_SCCS) && !defined(lint) +static char rcsid[] = "$OpenBSD: mktemp.c,v 1.13 1998/06/30 23:03:13 deraadt Exp $"; +#endif /* LIBC_SCCS and not lint */ + +#include +#include +#include +#include +#include +#include +#include +#include + +static int _gettemp __P((char *, int *, int, int)); + +int +mkstemps(path, slen) + char *path; + int slen; +{ + int fd; + + return (_gettemp(path, &fd, 0, slen) ? fd : -1); +} + +int +mkstemp(path) + char *path; +{ + int fd; + + return (_gettemp(path, &fd, 0, 0) ? fd : -1); +} + +char * +mkdtemp(path) + char *path; +{ + return(_gettemp(path, (int *)NULL, 1, 0) ? path : (char *)NULL); +} + +static int +_gettemp(path, doopen, domkdir, slen) + char *path; + register int *doopen; + int domkdir; + int slen; +{ + register char *start, *trv, *suffp; + struct stat sbuf; + int pid, rval; + + if (doopen && domkdir) { + errno = EINVAL; + return(0); + } + + for (trv = path; *trv; ++trv) + ; + trv -= slen; + suffp = trv; + --trv; + if (trv < path) { + errno = EINVAL; + return (0); + } + pid = getpid(); + while (*trv == 'X' && pid != 0) { + *trv-- = (pid % 10) + '0'; + pid /= 10; + } + while (*trv == 'X') { + char c; + + pid = (arc4random() & 0xffff) % (26+26); + if (pid < 26) + c = pid + 'A'; + else + c = (pid - 26) + 'a'; + *trv-- = c; + } + start = trv + 1; + + /* + * check the target directory; if you have six X's and it + * doesn't exist this runs for a *very* long time. + */ + if (doopen || domkdir) { + for (;; --trv) { + if (trv <= path) + break; + if (*trv == '/') { + *trv = '\0'; + rval = stat(path, &sbuf); + *trv = '/'; + if (rval != 0) + return(0); + if (!S_ISDIR(sbuf.st_mode)) { + errno = ENOTDIR; + return(0); + } + break; + } + } + } + + for (;;) { + if (doopen) { + if ((*doopen = + open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0) + return(1); + if (errno != EEXIST) + return(0); + } else if (domkdir) { + if (mkdir(path, 0700) == 0) + return(1); + if (errno != EEXIST) + return(0); + } else if (lstat(path, &sbuf)) + return(errno == ENOENT ? 1 : 0); + + /* tricky little algorithm for backward compatibility */ + for (trv = start;;) { + if (!*trv) + return (0); + if (*trv == 'Z') { + if (trv == suffp) + return (0); + *trv++ = 'a'; + } else { + if (isdigit(*trv)) + *trv = 'a'; + else if (*trv == 'z') /* inc from z to A */ + *trv = 'A'; + else { + if (trv == suffp) + return (0); + ++*trv; + } + break; + } + } + } + /*NOTREACHED*/ +} diff --git a/mktemp.h b/mktemp.h new file mode 100644 index 00000000..5d380058 --- /dev/null +++ b/mktemp.h @@ -0,0 +1,7 @@ +#ifndef _MKTEMP_H +#define _MKTEMP_H +int mkstemps(char *path, int slen); +int mkstemp(char *path); +char *mkdtemp(char *path); + +#endif /* _MKTEMP_H */ diff --git a/mpaux.c b/mpaux.c new file mode 100644 index 00000000..7760b4cf --- /dev/null +++ b/mpaux.c @@ -0,0 +1,46 @@ +/* + +mpaux.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sun Jul 16 04:29:30 1995 ylo + +This file contains various auxiliary functions related to multiple +precision integers. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include +#include "getput.h" +#include "xmalloc.h" + +#include + +void +compute_session_id(unsigned char session_id[16], + unsigned char cookie[8], + unsigned int host_key_bits, + BIGNUM *host_key_n, + unsigned int session_key_bits, + BIGNUM *session_key_n) +{ + unsigned int bytes = (host_key_bits + 7) / 8 + (session_key_bits + 7) / 8 + 8; + unsigned char *buf = xmalloc(bytes); + MD5_CTX md; + + BN_bn2bin(host_key_n, buf); + BN_bn2bin(session_key_n, buf + (host_key_bits + 7 ) / 8); + memcpy(buf + (host_key_bits + 7) / 8 + (session_key_bits + 7) / 8, + cookie, 8); + MD5_Init(&md); + MD5_Update(&md, buf, bytes); + MD5_Final(session_id, &md); + xfree(buf); +} diff --git a/mpaux.h b/mpaux.h new file mode 100644 index 00000000..240d6f7f --- /dev/null +++ b/mpaux.h @@ -0,0 +1,32 @@ +/* + +mpaux.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sun Jul 16 04:29:30 1995 ylo + +This file contains various auxiliary functions related to multiple +precision integers. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef MPAUX_H +#define MPAUX_H + +/* Computes a 16-byte session id in the global variable session_id. + The session id is computed by concatenating the linearized, msb + first representations of host_key_n, session_key_n, and the cookie. */ +void compute_session_id(unsigned char session_id[16], + unsigned char cookie[8], + unsigned int host_key_bits, + BIGNUM *host_key_n, + unsigned int session_key_bits, + BIGNUM *session_key_n); + +#endif /* MPAUX_H */ diff --git a/nchan.c b/nchan.c new file mode 100644 index 00000000..227e52f7 --- /dev/null +++ b/nchan.c @@ -0,0 +1,187 @@ +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" + +#include "buffer.h" +#include "packet.h" +#include "channels.h" +#include "nchan.h" + +static void chan_send_ieof(Channel *c); +static void chan_send_oclose(Channel *c); +static void chan_shutdown_write(Channel *c); +static void chan_shutdown_read(Channel *c); +static void chan_delele_if_full_closed(Channel *c); + +/* + * EVENTS: update channel input/output states + * execute ACTIONS + */ +/* events concerning the INPUT from socket for channel (istate) */ +void +chan_rcvd_oclose(Channel *c){ + switch(c->istate){ + case CHAN_INPUT_WAIT_OCLOSE: + debug("channel %d: INPUT_WAIT_OCLOSE -> INPUT_CLOSED [rcvd OCLOSE]", c->self); + c->istate=CHAN_INPUT_CLOSED; + chan_delele_if_full_closed(c); + break; + case CHAN_INPUT_OPEN: + debug("channel %d: INPUT_OPEN -> INPUT_CLOSED [rvcd OCLOSE, send IEOF]", c->self); + chan_shutdown_read(c); + chan_send_ieof(c); + c->istate=CHAN_INPUT_CLOSED; + chan_delele_if_full_closed(c); + break; + default: + debug("protocol error: chan_rcvd_oclose %d for istate %d",c->self,c->istate); + break; + } +} +void +chan_read_failed(Channel *c){ + switch(c->istate){ + case CHAN_INPUT_OPEN: + debug("channel %d: INPUT_OPEN -> INPUT_WAIT_DRAIN [read failed]", c->self); + chan_shutdown_read(c); + c->istate=CHAN_INPUT_WAIT_DRAIN; + break; + default: + debug("internal error: we do not read, but chan_read_failed %d for istate %d", + c->self,c->istate); + break; + } +} +void +chan_ibuf_empty(Channel *c){ + if(buffer_len(&c->input)){ + debug("internal error: chan_ibuf_empty %d for non empty buffer",c->self); + return; + } + switch(c->istate){ + case CHAN_INPUT_WAIT_DRAIN: + debug("channel %d: INPUT_WAIT_DRAIN -> INPUT_WAIT_OCLOSE [inbuf empty, send IEOF]", c->self); + chan_send_ieof(c); + c->istate=CHAN_INPUT_WAIT_OCLOSE; + break; + default: + debug("internal error: chan_ibuf_empty %d for istate %d",c->self,c->istate); + break; + } +} +/* events concerning the OUTPUT from channel for socket (ostate) */ +void +chan_rcvd_ieof(Channel *c){ + switch(c->ostate){ + case CHAN_OUTPUT_OPEN: + debug("channel %d: OUTPUT_OPEN -> OUTPUT_WAIT_DRAIN [rvcd IEOF]", c->self); + c->ostate=CHAN_OUTPUT_WAIT_DRAIN; + break; + case CHAN_OUTPUT_WAIT_IEOF: + debug("channel %d: OUTPUT_WAIT_IEOF -> OUTPUT_CLOSED [rvcd IEOF]", c->self); + c->ostate=CHAN_OUTPUT_CLOSED; + chan_delele_if_full_closed(c); + break; + default: + debug("protocol error: chan_rcvd_ieof %d for ostate %d", c->self,c->ostate); + break; + } +} +void +chan_write_failed(Channel *c){ + switch(c->ostate){ + case CHAN_OUTPUT_OPEN: + debug("channel %d: OUTPUT_OPEN -> OUTPUT_WAIT_IEOF [write failed]", c->self); + chan_send_oclose(c); + c->ostate=CHAN_OUTPUT_WAIT_IEOF; + break; + case CHAN_OUTPUT_WAIT_DRAIN: + debug("channel %d: OUTPUT_WAIT_DRAIN -> OUTPUT_CLOSED [write failed]", c->self); + chan_send_oclose(c); + c->ostate=CHAN_OUTPUT_CLOSED; + chan_delele_if_full_closed(c); + break; + default: + debug("internal error: chan_write_failed %d for ostate %d",c->self,c->ostate); + break; + } +} +void +chan_obuf_empty(Channel *c){ + if(buffer_len(&c->output)){ + debug("internal error: chan_obuf_empty %d for non empty buffer",c->self); + return; + } + switch(c->ostate){ + case CHAN_OUTPUT_WAIT_DRAIN: + debug("channel %d: OUTPUT_WAIT_DRAIN -> OUTPUT_CLOSED [obuf empty, send OCLOSE]", c->self); + chan_send_oclose(c); + c->ostate=CHAN_OUTPUT_CLOSED; + chan_delele_if_full_closed(c); + break; + default: + debug("internal error: chan_obuf_empty %d for ostate %d",c->self,c->ostate); + break; + } +} +/* + * ACTIONS: should never update c->istate or c->ostate + */ +static void +chan_send_ieof(Channel *c){ + switch(c->istate){ + case CHAN_INPUT_OPEN: + case CHAN_INPUT_WAIT_DRAIN: + packet_start(SSH_MSG_CHANNEL_INPUT_EOF); + packet_put_int(c->remote_id); + packet_send(); + break; + default: + debug("internal error: channel %d: cannot send IEOF for istate %d",c->self,c->istate); + break; + } +} +static void +chan_send_oclose(Channel *c){ + switch(c->ostate){ + case CHAN_OUTPUT_OPEN: + case CHAN_OUTPUT_WAIT_DRAIN: + chan_shutdown_write(c); + buffer_consume(&c->output, buffer_len(&c->output)); + packet_start(SSH_MSG_CHANNEL_OUTPUT_CLOSE); + packet_put_int(c->remote_id); + packet_send(); + break; + default: + debug("internal error: channel %d: cannot send OCLOSE for ostate %d",c->self,c->istate); + break; + } +} +/* helper */ +static void +chan_shutdown_write(Channel *c){ + debug("channel %d: shutdown_write", c->self); + if(shutdown(c->sock, SHUT_WR)<0) + error("chan_shutdown_write failed for #%d/fd%d: %.100s", + c->self, c->sock, strerror(errno)); +} +static void +chan_shutdown_read(Channel *c){ + debug("channel %d: shutdown_read", c->self); + if(shutdown(c->sock, SHUT_RD)<0) + error("chan_shutdown_read failed for #%d/fd%d: %.100s", + c->self, c->sock, strerror(errno)); +} +static void +chan_delele_if_full_closed(Channel *c){ + if(c->istate==CHAN_INPUT_CLOSED && c->ostate==CHAN_OUTPUT_CLOSED){ + debug("channel %d: closing", c->self); + channel_free(c->self); + } +} +void +chan_init_iostates(Channel *c){ + c->ostate=CHAN_OUTPUT_OPEN; + c->istate=CHAN_INPUT_OPEN; +} diff --git a/nchan.h b/nchan.h new file mode 100644 index 00000000..4e3a129b --- /dev/null +++ b/nchan.h @@ -0,0 +1,57 @@ +/* RCSID("$Id$"); */ + +#ifndef NCHAN_H +#define NCHAN_H + +/* + * SSH Protocol 1.5 aka New Channel Protocol + * Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored. + * Written by Markus Friedl in October 1999 + * + * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the + * tear down of channels: + * + * 1.3: strict request-ack-protocol: + * CLOSE -> + * <- CLOSE_CONFIRM + * + * 1.5: uses variations of: + * IEOF -> + * <- OCLOSE + * <- IEOF + * OCLOSE -> + * i.e. both sides have to close the channel + * + * See the debugging output from 'ssh -v' and 'sshd -d' of + * ssh-1.2.27 as an example. + * + */ + +/* ssh-proto-1.5 overloads prot-1.3-message-types */ +#define SSH_MSG_CHANNEL_INPUT_EOF SSH_MSG_CHANNEL_CLOSE +#define SSH_MSG_CHANNEL_OUTPUT_CLOSE SSH_MSG_CHANNEL_CLOSE_CONFIRMATION + +/* possible input states */ +#define CHAN_INPUT_OPEN 0x01 +#define CHAN_INPUT_WAIT_DRAIN 0x02 +#define CHAN_INPUT_WAIT_OCLOSE 0x04 +#define CHAN_INPUT_CLOSED 0x08 + +/* possible output states */ +#define CHAN_OUTPUT_OPEN 0x10 +#define CHAN_OUTPUT_WAIT_DRAIN 0x20 +#define CHAN_OUTPUT_WAIT_IEOF 0x40 +#define CHAN_OUTPUT_CLOSED 0x80 + +/* EVENTS for the input state */ +void chan_rcvd_oclose(Channel *c); +void chan_read_failed(Channel *c); +void chan_ibuf_empty(Channel *c); + +/* EVENTS for the output state */ +void chan_rcvd_ieof(Channel *c); +void chan_write_failed(Channel *c); +void chan_obuf_empty(Channel *c); + +void chan_init_iostates(Channel *c); +#endif diff --git a/nchan.ms b/nchan.ms new file mode 100644 index 00000000..b01512f7 --- /dev/null +++ b/nchan.ms @@ -0,0 +1,71 @@ +.TL +OpenSSH Channel Close Protocol 1.5 Implementation +.SH +Channel Input State Diagram +.PS +reset +l=1 +s=1.2 +ellipsewid=s*ellipsewid +boxwid=s*boxwid +ellipseht=s*ellipseht +S1: ellipse "INPUT" "OPEN" +move right 2*l from last ellipse.e +S4: ellipse "INPUT" "CLOSED" +move down l from last ellipse.s +S3: ellipse "INPUT" "WAIT" "OCLOSED" +move down l from 1st ellipse.s +S2: ellipse "INPUT" "WAIT" "DRAIN" +arrow "" "rcvd OCLOSE/" "shutdown_read" "send IEOF" from S1.e to S4.w +arrow "ibuf_empty/" "send IEOF" from S2.e to S3.w +arrow from S1.s to S2.n +box invis "read_failed/" "shutdown_read" with .e at last arrow.c +arrow from S3.n to S4.s +box invis "rcvd OCLOSE/" "-" with .w at last arrow.c +ellipse wid .9*ellipsewid ht .9*ellipseht at S4 +arrow "start" "" from S1.w+(-0.5,0) to S1.w +.PE +.SH +Channel Output State Diagram +.PS +S1: ellipse "OUTPUT" "OPEN" +move right 2*l from last ellipse.e +S3: ellipse "OUTPUT" "WAIT" "IEOF" +move down l from last ellipse.s +S4: ellipse "OUTPUT" "CLOSED" +move down l from 1st ellipse.s +S2: ellipse "OUTPUT" "WAIT" "DRAIN" +arrow "" "write_failed/" "shutdown_write" "send OCLOSE" from S1.e to S3.w +arrow "obuf_empty ||" "write_failed/" "shutdown_write" "send OCLOSE" from S2.e to S4.w +arrow from S1.s to S2.n +box invis "rcvd IEOF/" "-" with .e at last arrow.c +arrow from S3.s to S4.n +box invis "rcvd IEOF/" "-" with .w at last arrow.c +ellipse wid .9*ellipsewid ht .9*ellipseht at S4 +arrow "start" "" from S1.w+(-0.5,0) to S1.w +.PE +.SH +Notes +.PP +The input buffer is filled with data from the socket +(the socket represents the local comsumer/producer of the +forwarded channel). +The data is then sent over the INPUT-end of the channel to the +remote peer. +Data sent by the peer is received on the OUTPUT-end, +saved in the output buffer and written to the socket. +.PP +If the local protocol instance has forwarded all data on the +INPUT-end of the channel, it sends an IEOF message to the peer. +If the peer receives the IEOF and has comsumed all +data he replies with an OCLOSE. +When the local instance receives the OCLOSE +he considers the INPUT-half of the channel closed. +The peer has his OUTOUT-half closed. +.PP +A channel can be deallocated by a protocol instance +if both the INPUT- and the OUTOUT-half on his +side of the channel are closed. +Note that when an instance is unable to comsume the +received data, he is permitted to send an OCLOSE +before the matching IEOF is received. diff --git a/openssh.spec b/openssh.spec new file mode 100644 index 00000000..7ce58849 --- /dev/null +++ b/openssh.spec @@ -0,0 +1,105 @@ +Summary: OpenSSH free Secure Shell (SSH) implementation +Name: openssh +Version: 1.2pre3 +Release: 1 +Packager: Damien Miller +Source0: openssh-%{version}-linux.tar.gz +Copyright: BSD +Group: Applications/Internet +BuildRoot: /tmp/openssh-%{version}-buildroot + +%description +Ssh (Secure Shell) a program for logging into a remote machine and for +executing commands in a remote machine. It is intended to replace +rlogin and rsh, and provide secure encrypted communications between +two untrusted hosts over an insecure network. X11 connections and +arbitrary TCP/IP ports can also be forwarded over the secure channel. + +OpenSSH is OpenBSD's rework of the last free version of SSH, bringing it +up to date in terms of security and features, as well as removing all +patented algorithms to seperate libraries (OpenSSL). + +%changelog +* Wed Oct 27 1999 Damien Miller +- Initial RPMification, based on Jan "Yenya" Kasprzak's spec. + +%prep + +%setup -n openssh + +%build + +make -f Makefile.GNU OPT_FLAGS="$RPM_OPT_FLAGS" + +%install +rm -rf $RPM_BUILD_ROOT +mkdir -p $RPM_BUILD_ROOT/usr/bin +mkdir -p $RPM_BUILD_ROOT/usr/sbin +mkdir -p $RPM_BUILD_ROOT/etc/rc.d/init.d +mkdir -p $RPM_BUILD_ROOT/etc/pam.d +mkdir -p $RPM_BUILD_ROOT/etc/ssh +mkdir -p $RPM_BUILD_ROOT/usr/man/man1 +mkdir -p $RPM_BUILD_ROOT/usr/man/man8 + +install -m644 ssh.pam $RPM_BUILD_ROOT/etc/pam.d/ssh +install -m755 sshd.init $RPM_BUILD_ROOT/etc/rc.d/init.d/sshd +install -m600 ssh_config $RPM_BUILD_ROOT/etc/ssh/ssh_config +install -m600 sshd_config $RPM_BUILD_ROOT/etc/ssh/sshd_config + +install -s -m755 bin/sshd $RPM_BUILD_ROOT/usr/sbin +install -s -m755 bin/ssh $RPM_BUILD_ROOT/usr/bin +install -s -m755 bin/scp $RPM_BUILD_ROOT/usr/bin +install -s -m755 bin/ssh-agent $RPM_BUILD_ROOT/usr/bin +install -s -m755 bin/ssh-add $RPM_BUILD_ROOT/usr/bin +install -s -m755 bin/ssh-keygen $RPM_BUILD_ROOT/usr/bin + +install -m644 sshd.8 $RPM_BUILD_ROOT/usr/man/man8 +install -m644 ssh.1 $RPM_BUILD_ROOT/usr/man/man1 +install -m644 scp.1 $RPM_BUILD_ROOT/usr/man/man1 +install -m644 ssh-agent.1 $RPM_BUILD_ROOT/usr/man/man1 +install -m644 ssh-add.1 $RPM_BUILD_ROOT/usr/man/man1 +install -m644 ssh-keygen.1 $RPM_BUILD_ROOT/usr/man/man1 + +%clean +rm -rf $RPM_BUILD_ROOT + +%post +/sbin/chkconfig --add sshd +if [ ! -f /etc/ssh/ssh_host_key -o ! -s /etc/ssh/ssh_host_key ]; then + /usr/bin/ssh-keygen -b 1024 -f /etc/ssh/ssh_host_key -N '' >&2 +fi +if test -r /var/run/sshd.pid +then + /etc/rc.d/init.d/sshd restart >&2 +fi + +%preun +if [ "$1" = 0 ] +then + /etc/rc.d/init.d/sshd stop >&2 + /sbin/chkconfig --del sshd +fi + +%files +%defattr(-,root,root) +%doc COPYING.Ylonen ChangeLog ChangeLog.linux OVERVIEW +%doc README README.openssh +%attr(0755,root,root) /usr/sbin/sshd +%attr(0755,root,root) /usr/bin/ssh +%attr(0755,root,root) /usr/bin/ssh-agent +%attr(0755,root,root) /usr/bin/ssh-keygen +%attr(0755,root,root) /usr/bin/ssh-add +%attr(0755,root,root) /usr/bin/scp + +%attr(0755,root,root) /usr/man/man8/sshd.8 +%attr(0755,root,root) /usr/man/man1/ssh.1 +%attr(0755,root,root) /usr/man/man1/ssh-agent.1 +%attr(0755,root,root) /usr/man/man1/ssh-keygen.1 +%attr(0755,root,root) /usr/man/man1/ssh-add.1 +%attr(0755,root,root) /usr/man/man1/scp.1 + +%attr(0600,root,root) %config /etc/ssh/sshd_config +%attr(0600,root,root) %config /etc/pam.d/ssh +%attr(0755,root,root) %config /etc/rc.d/init.d/sshd +%attr(0644,root,root) %config /etc/ssh/ssh_config + diff --git a/packet.c b/packet.c new file mode 100644 index 00000000..79059985 --- /dev/null +++ b/packet.c @@ -0,0 +1,762 @@ +/* + +packet.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Mar 18 02:40:40 1995 ylo + +This file contains code implementing the packet protocol and communication +with the other side. This same code is used both on client and server side. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "xmalloc.h" +#include "buffer.h" +#include "packet.h" +#include "bufaux.h" +#include "ssh.h" +#include "crc32.h" +#include "cipher.h" +#include "getput.h" + +#include "compress.h" +#include "deattack.h" + +/* This variable contains the file descriptors used for communicating with + the other side. connection_in is used for reading; connection_out + for writing. These can be the same descriptor, in which case it is + assumed to be a socket. */ +static int connection_in = -1; +static int connection_out = -1; + +/* Cipher type. This value is only used to determine whether to pad the + packets with zeroes or random data. */ +static int cipher_type = SSH_CIPHER_NONE; + +/* Protocol flags for the remote side. */ +static unsigned int remote_protocol_flags = 0; + +/* Encryption context for receiving data. This is only used for decryption. */ +static CipherContext receive_context; +/* Encryption coontext for sending data. This is only used for encryption. */ +static CipherContext send_context; + +/* Buffer for raw input data from the socket. */ +static Buffer input; + +/* Buffer for raw output data going to the socket. */ +static Buffer output; + +/* Buffer for the partial outgoing packet being constructed. */ +static Buffer outgoing_packet; + +/* Buffer for the incoming packet currently being processed. */ +static Buffer incoming_packet; + +/* Scratch buffer for packet compression/decompression. */ +static Buffer compression_buffer; + +/* Flag indicating whether packet compression/decompression is enabled. */ +static int packet_compression = 0; + +/* Flag indicating whether this module has been initialized. */ +static int initialized = 0; + +/* Set to true if the connection is interactive. */ +static int interactive_mode = 0; + +/* Sets the descriptors used for communication. Disables encryption until + packet_set_encryption_key is called. */ + +void +packet_set_connection(int fd_in, int fd_out) +{ + connection_in = fd_in; + connection_out = fd_out; + cipher_type = SSH_CIPHER_NONE; + cipher_set_key(&send_context, SSH_CIPHER_NONE, (unsigned char *)"", 0, 1); + cipher_set_key(&receive_context, SSH_CIPHER_NONE, (unsigned char *)"", 0, 0); + if (!initialized) + { + initialized = 1; + buffer_init(&input); + buffer_init(&output); + buffer_init(&outgoing_packet); + buffer_init(&incoming_packet); + } + + /* Kludge: arrange the close function to be called from fatal(). */ + fatal_add_cleanup((void (*)(void *))packet_close, NULL); +} + +/* Sets the connection into non-blocking mode. */ + +void +packet_set_nonblocking() +{ + /* Set the socket into non-blocking mode. */ + if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) + error("fcntl O_NONBLOCK: %.100s", strerror(errno)); + + if (connection_out != connection_in) + { + if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0) + error("fcntl O_NONBLOCK: %.100s", strerror(errno)); + } +} + +/* Returns the socket used for reading. */ + +int +packet_get_connection_in() +{ + return connection_in; +} + +/* Returns the descriptor used for writing. */ + +int +packet_get_connection_out() +{ + return connection_out; +} + +/* Closes the connection and clears and frees internal data structures. */ + +void +packet_close() +{ + if (!initialized) + return; + initialized = 0; + if (connection_in == connection_out) + { + shutdown(connection_out, SHUT_RDWR); + close(connection_out); + } + else + { + close(connection_in); + close(connection_out); + } + buffer_free(&input); + buffer_free(&output); + buffer_free(&outgoing_packet); + buffer_free(&incoming_packet); + if (packet_compression) + { + buffer_free(&compression_buffer); + buffer_compress_uninit(); + } +} + +/* Sets remote side protocol flags. */ + +void +packet_set_protocol_flags(unsigned int protocol_flags) +{ + remote_protocol_flags = protocol_flags; + channel_set_options((protocol_flags & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) != 0); +} + +/* Returns the remote protocol flags set earlier by the above function. */ + +unsigned int +packet_get_protocol_flags() +{ + return remote_protocol_flags; +} + +/* Starts packet compression from the next packet on in both directions. + Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. */ + +void +packet_start_compression(int level) +{ + if (packet_compression) + fatal("Compression already enabled."); + packet_compression = 1; + buffer_init(&compression_buffer); + buffer_compress_init(level); +} + +/* Encrypts the given number of bytes, copying from src to dest. + bytes is known to be a multiple of 8. */ + +void +packet_encrypt(CipherContext *cc, void *dest, void *src, + unsigned int bytes) +{ + assert((bytes % 8) == 0); + cipher_encrypt(cc, dest, src, bytes); +} + +/* Decrypts the given number of bytes, copying from src to dest. + bytes is known to be a multiple of 8. */ + +void +packet_decrypt(CipherContext *cc, void *dest, void *src, + unsigned int bytes) +{ + int i; + + assert((bytes % 8) == 0); + + /* + Cryptographic attack detector for ssh - Modifications for packet.c + (C)1998 CORE-SDI, Buenos Aires Argentina + Ariel Futoransky(futo@core-sdi.com) + */ + switch (cc->type) + { + case SSH_CIPHER_NONE: + i = DEATTACK_OK; + break; + default: + i = detect_attack(src, bytes, NULL); + break; + } + + if (i == DEATTACK_DETECTED) + packet_disconnect("crc32 compensation attack: network attack detected"); + + cipher_decrypt(cc, dest, src, bytes); +} + +/* Causes any further packets to be encrypted using the given key. The same + key is used for both sending and reception. However, both directions + are encrypted independently of each other. */ + +void +packet_set_encryption_key(const unsigned char *key, unsigned int keylen, + int cipher, int is_client) +{ + cipher_type = cipher; + if (cipher == SSH_CIPHER_RC4) + { + if (is_client) + { /* In client: use first half for receiving, second for sending. */ + cipher_set_key(&receive_context, cipher, key, keylen / 2, 0); + cipher_set_key(&send_context, cipher, key + keylen / 2, + keylen / 2, 1); + } + else + { /* In server: use first half for sending, second for receiving. */ + cipher_set_key(&receive_context, cipher, key + keylen / 2, + keylen / 2, 0); + cipher_set_key(&send_context, cipher, key, keylen / 2, 1); + } + } + else + { + /* All other ciphers use the same key in both directions for now. */ + cipher_set_key(&receive_context, cipher, key, keylen, 0); + cipher_set_key(&send_context, cipher, key, keylen, 1); + } +} + +/* Starts constructing a packet to send. */ + +void +packet_start(int type) +{ + char buf[9]; + + buffer_clear(&outgoing_packet); + memset(buf, 0, 8); + buf[8] = type; + buffer_append(&outgoing_packet, buf, 9); +} + +/* Appends a character to the packet data. */ + +void +packet_put_char(int value) +{ + char ch = value; + buffer_append(&outgoing_packet, &ch, 1); +} + +/* Appends an integer to the packet data. */ + +void +packet_put_int(unsigned int value) +{ + buffer_put_int(&outgoing_packet, value); +} + +/* Appends a string to packet data. */ + +void +packet_put_string(const char *buf, unsigned int len) +{ + buffer_put_string(&outgoing_packet, buf, len); +} + +/* Appends an arbitrary precision integer to packet data. */ + +void +packet_put_bignum(BIGNUM *value) +{ + buffer_put_bignum(&outgoing_packet, value); +} + +/* Finalizes and sends the packet. If the encryption key has been set, + encrypts the packet before sending. */ + +void +packet_send() +{ + char buf[8], *cp; + int i, padding, len; + unsigned int checksum; + u_int32_t rand = 0; + + /* If using packet compression, compress the payload of the outgoing + packet. */ + if (packet_compression) + { + buffer_clear(&compression_buffer); + buffer_consume(&outgoing_packet, 8); /* Skip padding. */ + buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); /* padding */ + buffer_compress(&outgoing_packet, &compression_buffer); + buffer_clear(&outgoing_packet); + buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), + buffer_len(&compression_buffer)); + } + + /* Compute packet length without padding (add checksum, remove padding). */ + len = buffer_len(&outgoing_packet) + 4 - 8; + + /* Insert padding. */ + padding = 8 - len % 8; + if (cipher_type != SSH_CIPHER_NONE) + { + cp = buffer_ptr(&outgoing_packet); + for (i = 0; i < padding; i++) { + if (i % 4 == 0) + rand = arc4random(); + cp[7 - i] = rand & 0xff; + rand >>= 8; + } + } + buffer_consume(&outgoing_packet, 8 - padding); + + /* Add check bytes. */ + checksum = crc32((unsigned char *)buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); + PUT_32BIT(buf, checksum); + buffer_append(&outgoing_packet, buf, 4); + +#ifdef PACKET_DEBUG + fprintf(stderr, "packet_send plain: "); + buffer_dump(&outgoing_packet); +#endif + + /* Append to output. */ + PUT_32BIT(buf, len); + buffer_append(&output, buf, 4); + buffer_append_space(&output, &cp, buffer_len(&outgoing_packet)); + packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); + +#ifdef PACKET_DEBUG + fprintf(stderr, "encrypted: "); buffer_dump(&output); +#endif + + buffer_clear(&outgoing_packet); + + /* Note that the packet is now only buffered in output. It won\'t be + actually sent until packet_write_wait or packet_write_poll is called. */ +} + +/* Waits until a packet has been received, and returns its type. Note that + no other data is processed until this returns, so this function should + not be used during the interactive session. */ + +int +packet_read(int *payload_len_ptr) +{ + int type, len; + fd_set set; + char buf[8192]; + + /* Since we are blocking, ensure that all written packets have been sent. */ + packet_write_wait(); + + /* Stay in the loop until we have received a complete packet. */ + for (;;) + { + /* Try to read a packet from the buffer. */ + type = packet_read_poll(payload_len_ptr); + if (type == SSH_SMSG_SUCCESS + || type == SSH_SMSG_FAILURE + || type == SSH_CMSG_EOF + || type == SSH_CMSG_EXIT_CONFIRMATION) + packet_integrity_check(*payload_len_ptr, 0, type); + /* If we got a packet, return it. */ + if (type != SSH_MSG_NONE) + return type; + /* Otherwise, wait for some data to arrive, add it to the buffer, + and try again. */ + FD_ZERO(&set); + FD_SET(connection_in, &set); + /* Wait for some data to arrive. */ + select(connection_in + 1, &set, NULL, NULL, NULL); + /* Read data from the socket. */ + len = read(connection_in, buf, sizeof(buf)); + if (len == 0) + fatal("Connection closed by remote host."); + if (len < 0) + fatal("Read from socket failed: %.100s", strerror(errno)); + /* Append it to the buffer. */ + packet_process_incoming(buf, len); + } + /*NOTREACHED*/ +} + +/* Waits until a packet has been received, verifies that its type matches + that given, and gives a fatal error and exits if there is a mismatch. */ + +void +packet_read_expect(int *payload_len_ptr, int expected_type) +{ + int type; + + type = packet_read(payload_len_ptr); + if (type != expected_type) + packet_disconnect("Protocol error: expected packet type %d, got %d", + expected_type, type); +} + +/* Checks if a full packet is available in the data received so far via + packet_process_incoming. If so, reads the packet; otherwise returns + SSH_MSG_NONE. This does not wait for data from the connection. + + SSH_MSG_DISCONNECT is handled specially here. Also, + SSH_MSG_IGNORE messages are skipped by this function and are never returned + to higher levels. + + The returned payload_len does include space consumed by: + Packet length + Padding + Packet type + Check bytes + + + */ + +int +packet_read_poll(int *payload_len_ptr) +{ + unsigned int len, padded_len; + unsigned char *ucp; + char buf[8], *cp; + unsigned int checksum, stored_checksum; + + restart: + + /* Check if input size is less than minimum packet size. */ + if (buffer_len(&input) < 4 + 8) + return SSH_MSG_NONE; + /* Get length of incoming packet. */ + ucp = (unsigned char *)buffer_ptr(&input); + len = GET_32BIT(ucp); + if (len < 1 + 2 + 2 || len > 256*1024) + packet_disconnect("Bad packet length %d.", len); + padded_len = (len + 8) & ~7; + + /* Check if the packet has been entirely received. */ + if (buffer_len(&input) < 4 + padded_len) + return SSH_MSG_NONE; + + /* The entire packet is in buffer. */ + + /* Consume packet length. */ + buffer_consume(&input, 4); + + /* Copy data to incoming_packet. */ + buffer_clear(&incoming_packet); + buffer_append_space(&incoming_packet, &cp, padded_len); + packet_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len); + buffer_consume(&input, padded_len); + +#ifdef PACKET_DEBUG + fprintf(stderr, "read_poll plain: "); buffer_dump(&incoming_packet); +#endif + + /* Compute packet checksum. */ + checksum = crc32((unsigned char *)buffer_ptr(&incoming_packet), + buffer_len(&incoming_packet) - 4); + + /* Skip padding. */ + buffer_consume(&incoming_packet, 8 - len % 8); + + /* Test check bytes. */ + assert(len == buffer_len(&incoming_packet)); + ucp = (unsigned char *)buffer_ptr(&incoming_packet) + len - 4; + stored_checksum = GET_32BIT(ucp); + if (checksum != stored_checksum) + packet_disconnect("Corrupted check bytes on input."); + buffer_consume_end(&incoming_packet, 4); + + /* If using packet compression, decompress the packet. */ + if (packet_compression) + { + buffer_clear(&compression_buffer); + buffer_uncompress(&incoming_packet, &compression_buffer); + buffer_clear(&incoming_packet); + buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), + buffer_len(&compression_buffer)); + } + + /* Get packet type. */ + buffer_get(&incoming_packet, &buf[0], 1); + + /* Return length of payload (without type field). */ + *payload_len_ptr = buffer_len(&incoming_packet); + + /* Handle disconnect message. */ + if ((unsigned char)buf[0] == SSH_MSG_DISCONNECT) + fatal("%.900s", packet_get_string(NULL)); + + /* Ignore ignore messages. */ + if ((unsigned char)buf[0] == SSH_MSG_IGNORE) + goto restart; + + /* Send debug messages as debugging output. */ + if ((unsigned char)buf[0] == SSH_MSG_DEBUG) + { + debug("Remote: %.900s", packet_get_string(NULL)); + goto restart; + } + + /* Return type. */ + return (unsigned char)buf[0]; +} + +/* Buffers the given amount of input characters. This is intended to be + used together with packet_read_poll. */ + +void +packet_process_incoming(const char *buf, unsigned int len) +{ + buffer_append(&input, buf, len); +} + +/* Returns a character from the packet. */ + +unsigned int +packet_get_char() +{ + char ch; + buffer_get(&incoming_packet, &ch, 1); + return (unsigned char)ch; +} + +/* Returns an integer from the packet data. */ + +unsigned int +packet_get_int() +{ + return buffer_get_int(&incoming_packet); +} + +/* Returns an arbitrary precision integer from the packet data. The integer + must have been initialized before this call. */ + +void +packet_get_bignum(BIGNUM *value, int *length_ptr) +{ + *length_ptr = buffer_get_bignum(&incoming_packet, value); +} + +/* Returns a string from the packet data. The string is allocated using + xmalloc; it is the responsibility of the calling program to free it when + no longer needed. The length_ptr argument may be NULL, or point to an + integer into which the length of the string is stored. */ + +char +*packet_get_string(unsigned int *length_ptr) +{ + return buffer_get_string(&incoming_packet, length_ptr); +} + +/* Sends a diagnostic message from the server to the client. This message + can be sent at any time (but not while constructing another message). + The message is printed immediately, but only if the client is being + executed in verbose mode. These messages are primarily intended to + ease debugging authentication problems. The length of the formatted + message must not exceed 1024 bytes. This will automatically call + packet_write_wait. */ + +void +packet_send_debug(const char *fmt, ...) +{ + char buf[1024]; + va_list args; + + va_start(args, fmt); + vsnprintf(buf, sizeof(buf), fmt, args); + va_end(args); + + packet_start(SSH_MSG_DEBUG); + packet_put_string(buf, strlen(buf)); + packet_send(); + packet_write_wait(); +} + +/* Logs the error plus constructs and sends a disconnect + packet, closes the connection, and exits. This function never returns. + The error message should not contain a newline. The length of the + formatted message must not exceed 1024 bytes. */ + +void +packet_disconnect(const char *fmt, ...) +{ + char buf[1024]; + va_list args; + static int disconnecting = 0; + if (disconnecting) /* Guard against recursive invocations. */ + fatal("packet_disconnect called recursively."); + disconnecting = 1; + + /* Format the message. Note that the caller must make sure the message + is of limited size. */ + va_start(args, fmt); + vsnprintf(buf, sizeof(buf), fmt, args); + va_end(args); + + /* Send the disconnect message to the other side, and wait for it to get + sent. */ + packet_start(SSH_MSG_DISCONNECT); + packet_put_string(buf, strlen(buf)); + packet_send(); + packet_write_wait(); + + /* Stop listening for connections. */ + channel_stop_listening(); + + /* Close the connection. */ + packet_close(); + + /* Display the error locally and exit. */ + fatal("Local: %.100s", buf); +} + +/* Checks if there is any buffered output, and tries to write some of the + output. */ + +void +packet_write_poll() +{ + int len = buffer_len(&output); + if (len > 0) + { + len = write(connection_out, buffer_ptr(&output), len); + if (len <= 0) { + if (errno == EAGAIN) + return; + else + fatal("Write failed: %.100s", strerror(errno)); + } + buffer_consume(&output, len); + } +} + +/* Calls packet_write_poll repeatedly until all pending output data has + been written. */ + +void +packet_write_wait() +{ + packet_write_poll(); + while (packet_have_data_to_write()) + { + fd_set set; + FD_ZERO(&set); + FD_SET(connection_out, &set); + select(connection_out + 1, NULL, &set, NULL, NULL); + packet_write_poll(); + } +} + +/* Returns true if there is buffered data to write to the connection. */ + +int +packet_have_data_to_write() +{ + return buffer_len(&output) != 0; +} + +/* Returns true if there is not too much data to write to the connection. */ + +int +packet_not_very_much_data_to_write() +{ + if (interactive_mode) + return buffer_len(&output) < 16384; + else + return buffer_len(&output) < 128*1024; +} + +/* Informs that the current session is interactive. Sets IP flags for that. */ + +void +packet_set_interactive(int interactive, int keepalives) +{ + int on = 1; + + /* Record that we are in interactive mode. */ + interactive_mode = interactive; + + /* Only set socket options if using a socket (as indicated by the descriptors + being the same). */ + if (connection_in != connection_out) + return; + + if (keepalives) + { + /* Set keepalives if requested. */ + if (setsockopt(connection_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, + sizeof(on)) < 0) + error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); + } + + if (interactive) + { + /* Set IP options for an interactive connection. Use IPTOS_LOWDELAY + and TCP_NODELAY. */ + int lowdelay = IPTOS_LOWDELAY; + if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *)&lowdelay, + sizeof(lowdelay)) < 0) + error("setsockopt IPTOS_LOWDELAY: %.100s", strerror(errno)); + if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *)&on, + sizeof(on)) < 0) + error("setsockopt TCP_NODELAY: %.100s", strerror(errno)); + } + else + { + /* Set IP options for a non-interactive connection. Use + IPTOS_THROUGHPUT. */ + int throughput = IPTOS_THROUGHPUT; + if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *)&throughput, + sizeof(throughput)) < 0) + error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); + } +} + +/* Returns true if the current connection is interactive. */ + +int +packet_is_interactive() +{ + return interactive_mode; +} diff --git a/packet.h b/packet.h new file mode 100644 index 00000000..2ea0ae43 --- /dev/null +++ b/packet.h @@ -0,0 +1,166 @@ +/* + +packet.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Mar 18 02:02:14 1995 ylo + +Interface for the packet protocol functions. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef PACKET_H +#define PACKET_H + +#include + +/* Sets the socket used for communication. Disables encryption until + packet_set_encryption_key is called. It is permissible that fd_in + and fd_out are the same descriptor; in that case it is assumed to + be a socket. */ +void packet_set_connection(int fd_in, int fd_out); + +/* Puts the connection file descriptors into non-blocking mode. */ +void packet_set_nonblocking(void); + +/* Returns the file descriptor used for input. */ +int packet_get_connection_in(void); + +/* Returns the file descriptor used for output. */ +int packet_get_connection_out(void); + +/* Closes the connection (both descriptors) and clears and frees + internal data structures. */ +void packet_close(void); + +/* Causes any further packets to be encrypted using the given key. The same + key is used for both sending and reception. However, both directions + are encrypted independently of each other. Cipher types are + defined in ssh.h. */ +void packet_set_encryption_key(const unsigned char *key, unsigned int keylen, + int cipher_type, int is_client); + +/* Sets remote side protocol flags for the current connection. This can + be called at any time. */ +void packet_set_protocol_flags(unsigned int flags); + +/* Returns the remote protocol flags set earlier by the above function. */ +unsigned int packet_get_protocol_flags(void); + +/* Enables compression in both directions starting from the next packet. */ +void packet_start_compression(int level); + +/* Informs that the current session is interactive. Sets IP flags for optimal + performance in interactive use. */ +void packet_set_interactive(int interactive, int keepalives); + +/* Returns true if the current connection is interactive. */ +int packet_is_interactive(void); + +/* Starts constructing a packet to send. */ +void packet_start(int type); + +/* Appends a character to the packet data. */ +void packet_put_char(int ch); + +/* Appends an integer to the packet data. */ +void packet_put_int(unsigned int value); + +/* Appends an arbitrary precision integer to packet data. */ +void packet_put_bignum(BIGNUM *value); + +/* Appends a string to packet data. */ +void packet_put_string(const char *buf, unsigned int len); + +/* Finalizes and sends the packet. If the encryption key has been set, + encrypts the packet before sending. */ +void packet_send(void); + +/* Waits until a packet has been received, and returns its type. */ +int packet_read(int *payload_len_ptr); + +/* Waits until a packet has been received, verifies that its type matches + that given, and gives a fatal error and exits if there is a mismatch. */ +void packet_read_expect(int *payload_len_ptr, int type); + +/* Checks if a full packet is available in the data received so far via + packet_process_incoming. If so, reads the packet; otherwise returns + SSH_MSG_NONE. This does not wait for data from the connection. + + SSH_MSG_DISCONNECT is handled specially here. Also, + SSH_MSG_IGNORE messages are skipped by this function and are never returned + to higher levels. */ +int packet_read_poll(int *packet_len_ptr); + +/* Buffers the given amount of input characters. This is intended to be + used together with packet_read_poll. */ +void packet_process_incoming(const char *buf, unsigned int len); + +/* Returns a character (0-255) from the packet data. */ +unsigned int packet_get_char(void); + +/* Returns an integer from the packet data. */ +unsigned int packet_get_int(void); + +/* Returns an arbitrary precision integer from the packet data. The integer + must have been initialized before this call. */ +void packet_get_bignum(BIGNUM *value, int *length_ptr); + +/* Returns a string from the packet data. The string is allocated using + xmalloc; it is the responsibility of the calling program to free it when + no longer needed. The length_ptr argument may be NULL, or point to an + integer into which the length of the string is stored. */ +char *packet_get_string(unsigned int *length_ptr); + +/* Logs the error in syslog using LOG_INFO, constructs and sends a disconnect + packet, closes the connection, and exits. This function never returns. + The error message should not contain a newline. The total length of the + message must not exceed 1024 bytes. */ +void packet_disconnect(const char *fmt, ...); + +/* Sends a diagnostic message to the other side. This message + can be sent at any time (but not while constructing another message). + The message is printed immediately, but only if the client is being + executed in verbose mode. These messages are primarily intended to + ease debugging authentication problems. The total length of the message + must not exceed 1024 bytes. This will automatically call + packet_write_wait. If the remote side protocol flags do not indicate + that it supports SSH_MSG_DEBUG, this will do nothing. */ +void packet_send_debug(const char *fmt, ...); + +/* Checks if there is any buffered output, and tries to write some of the + output. */ +void packet_write_poll(void); + +/* Waits until all pending output data has been written. */ +void packet_write_wait(void); + +/* Returns true if there is buffered data to write to the connection. */ +int packet_have_data_to_write(void); + +/* Returns true if there is not too much data to write to the connection. */ +int packet_not_very_much_data_to_write(void); + +/* Stores tty modes from the fd into current packet. */ +void tty_make_modes(int fd); + +/* Parses tty modes for the fd from the current packet. */ +void tty_parse_modes(int fd, int *n_bytes_ptr); + +#define packet_integrity_check(payload_len, expected_len, type) \ +do { \ + int _p = (payload_len), _e = (expected_len); \ + if (_p != _e) { \ + log("Packet integrity error (%d != %d) at %s:%d", \ + _p, _e, __FILE__, __LINE__); \ + packet_disconnect("Packet integrity error. (%d)", (type)); \ + } \ +} while (0) + +#endif /* PACKET_H */ diff --git a/pty.c b/pty.c new file mode 100644 index 00000000..2a7919aa --- /dev/null +++ b/pty.c @@ -0,0 +1,264 @@ +/* + +pty.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Fri Mar 17 04:37:25 1995 ylo + +Allocating a pseudo-terminal, and making it the controlling tty. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "pty.h" +#include "ssh.h" + +/* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */ +#if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY) +#undef HAVE_DEV_PTMX +#endif + +#ifndef O_NOCTTY +#define O_NOCTTY 0 +#endif + +/* Allocates and opens a pty. Returns 0 if no pty could be allocated, + or nonzero if a pty was successfully allocated. On success, open file + descriptors for the pty and tty sides and the name of the tty side are + returned (the buffer must be able to hold at least 64 characters). */ + +int pty_allocate(int *ptyfd, int *ttyfd, char *namebuf) +{ +#ifdef HAVE_OPENPTY + + /* openpty(3) exists in OSF/1 and some other os'es */ + + int i; + + i = openpty(ptyfd, ttyfd, namebuf, NULL, NULL); + + if (i < 0) + { + error("openpty: %.100s", strerror(errno)); + return 0; + } + + return 1; + +#else /* HAVE_OPENPTY */ +#ifdef HAVE__GETPTY + + /* _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more + pty's automagically when needed */ + + char *slave; + + slave = _getpty(ptyfd, O_RDWR, 0622, 0); + if (slave == NULL) + { + error("_getpty: %.100s", strerror(errno)); + return 0; + } + strcpy(namebuf, slave); + /* Open the slave side. */ + *ttyfd = open(namebuf, O_RDWR|O_NOCTTY); + if (*ttyfd < 0) + { + error("%.200s: %.100s", namebuf, strerror(errno)); + close(*ptyfd); + return 0; + } + return 1; + +#else /* HAVE__GETPTY */ +#ifdef HAVE_DEV_PTMX + /* This code is used e.g. on Solaris 2.x. (Note that Solaris 2.3 also has + bsd-style ptys, but they simply do not work.) */ + + int ptm; + char *pts; + + ptm = open("/dev/ptmx", O_RDWR|O_NOCTTY); + if (ptm < 0) + { + error("/dev/ptmx: %.100s", strerror(errno)); + return 0; + } + if (grantpt(ptm) < 0) + { + error("grantpt: %.100s", strerror(errno)); + return 0; + } + if (unlockpt(ptm) < 0) + { + error("unlockpt: %.100s", strerror(errno)); + return 0; + } + pts = ptsname(ptm); + if (pts == NULL) + error("Slave pty side name could not be obtained."); + strcpy(namebuf, pts); + *ptyfd = ptm; + + /* Open the slave side. */ + *ttyfd = open(namebuf, O_RDWR|O_NOCTTY); + if (*ttyfd < 0) + { + error("%.100s: %.100s", namebuf, strerror(errno)); + close(*ptyfd); + return 0; + } + /* Push the appropriate streams modules, as described in Solaris pts(7). */ + if (ioctl(*ttyfd, I_PUSH, "ptem") < 0) + error("ioctl I_PUSH ptem: %.100s", strerror(errno)); + if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0) + error("ioctl I_PUSH ldterm: %.100s", strerror(errno)); + if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0) + error("ioctl I_PUSH ttcompat: %.100s", strerror(errno)); + return 1; + +#else /* HAVE_DEV_PTMX */ +#ifdef HAVE_DEV_PTS_AND_PTC + + /* AIX-style pty code. */ + + const char *name; + + *ptyfd = open("/dev/ptc", O_RDWR|O_NOCTTY); + if (*ptyfd < 0) + { + error("Could not open /dev/ptc: %.100s", strerror(errno)); + return 0; + } + name = ttyname(*ptyfd); + if (!name) + fatal("Open of /dev/ptc returns device for which ttyname fails."); + strcpy(namebuf, name); + *ttyfd = open(name, O_RDWR|O_NOCTTY); + if (*ttyfd < 0) + { + error("Could not open pty slave side %.100s: %.100s", + name, strerror(errno)); + close(*ptyfd); + return 0; + } + return 1; + +#else /* HAVE_DEV_PTS_AND_PTC */ + /* BSD-style pty code. */ + + char buf[64]; + int i; + const char *ptymajors = + "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ"; + const char *ptyminors = "0123456789abcdef"; + int num_minors = strlen(ptyminors); + int num_ptys = strlen(ptymajors) * num_minors; + + for (i = 0; i < num_ptys; i++) + { + snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors], + ptyminors[i % num_minors]); + *ptyfd = open(buf, O_RDWR|O_NOCTTY); + if (*ptyfd < 0) + continue; + snprintf(namebuf, sizeof buf, "/dev/tty%c%c", ptymajors[i / num_minors], + ptyminors[i % num_minors]); + + /* Open the slave side. */ + *ttyfd = open(namebuf, O_RDWR|O_NOCTTY); + if (*ttyfd < 0) + { + error("%.100s: %.100s", namebuf, strerror(errno)); + close(*ptyfd); + return 0; + } + return 1; + } + return 0; +#endif /* HAVE_DEV_PTS_AND_PTC */ +#endif /* HAVE_DEV_PTMX */ +#endif /* HAVE__GETPTY */ +#endif /* HAVE_OPENPTY */ +} + +/* Releases the tty. Its ownership is returned to root, and permissions to + 0666. */ + +void pty_release(const char *ttyname) +{ + if (chown(ttyname, (uid_t)0, (gid_t)0) < 0) + debug("chown %.100s 0 0 failed: %.100s", ttyname, strerror(errno)); + if (chmod(ttyname, (mode_t)0666) < 0) + debug("chmod %.100s 0666 failed: %.100s", ttyname, strerror(errno)); +} + +/* Makes the tty the processes controlling tty and sets it to sane modes. */ + +void pty_make_controlling_tty(int *ttyfd, const char *ttyname) +{ + int fd; + + /* First disconnect from the old controlling tty. */ +#ifdef TIOCNOTTY + fd = open("/dev/tty", O_RDWR|O_NOCTTY); + if (fd >= 0) + { + (void)ioctl(fd, TIOCNOTTY, NULL); + close(fd); + } +#endif /* TIOCNOTTY */ + if (setsid() < 0) + error("setsid: %.100s", strerror(errno)); + + /* Verify that we are successfully disconnected from the controlling tty. */ + fd = open("/dev/tty", O_RDWR|O_NOCTTY); + if (fd >= 0) + { + error("Failed to disconnect from controlling tty."); + close(fd); + } + + /* Make it our controlling tty. */ +#ifdef TIOCSCTTY + debug("Setting controlling tty using TIOCSCTTY."); + /* We ignore errors from this, because HPSUX defines TIOCSCTTY, but returns + EINVAL with these arguments, and there is absolutely no documentation. */ + ioctl(*ttyfd, TIOCSCTTY, NULL); +#endif /* TIOCSCTTY */ + fd = open(ttyname, O_RDWR); + if (fd < 0) + error("%.100s: %.100s", ttyname, strerror(errno)); + else + close(fd); + + /* Verify that we now have a controlling tty. */ + fd = open("/dev/tty", O_WRONLY); + if (fd < 0) + error("open /dev/tty failed - could not set controlling tty: %.100s", + strerror(errno)); + else + { + close(fd); + } +} + +/* Changes the window size associated with the pty. */ + +void pty_change_window_size(int ptyfd, int row, int col, + int xpixel, int ypixel) +{ + struct winsize w; + w.ws_row = row; + w.ws_col = col; + w.ws_xpixel = xpixel; + w.ws_ypixel = ypixel; + (void)ioctl(ptyfd, TIOCSWINSZ, &w); +} + diff --git a/pty.h b/pty.h new file mode 100644 index 00000000..c6750581 --- /dev/null +++ b/pty.h @@ -0,0 +1,40 @@ +/* + +pty.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Fri Mar 17 05:03:28 1995 ylo + +Functions for allocating a pseudo-terminal and making it the controlling +tty. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef PTY_H +#define PTY_H + +/* Allocates and opens a pty. Returns 0 if no pty could be allocated, + or nonzero if a pty was successfully allocated. On success, open file + descriptors for the pty and tty sides and the name of the tty side are + returned (the buffer must be able to hold at least 64 characters). */ +int pty_allocate(int *ptyfd, int *ttyfd, char *ttyname); + +/* Releases the tty. Its ownership is returned to root, and permissions to + 0666. */ +void pty_release(const char *ttyname); + +/* Makes the tty the processes controlling tty and sets it to sane modes. + This may need to reopen the tty to get rid of possible eavesdroppers. */ +void pty_make_controlling_tty(int *ttyfd, const char *ttyname); + +/* Changes the window size associated with the pty. */ +void pty_change_window_size(int ptyfd, int row, int col, + int xpixel, int ypixel); + +#endif /* PTY_H */ diff --git a/radix.c b/radix.c new file mode 100644 index 00000000..1c497945 --- /dev/null +++ b/radix.c @@ -0,0 +1,258 @@ +/* + radix.c + + base-64 encoding pinched from lynx2-7-2, who pinched it from rpem. + Originally written by Mark Riordan 12 August 1990 and 17 Feb 1991 + and placed in the public domain. + + Dug Song +*/ + +#include "includes.h" + +#ifdef AFS +#include + +char six2pr[64] = { + 'A','B','C','D','E','F','G','H','I','J','K','L','M', + 'N','O','P','Q','R','S','T','U','V','W','X','Y','Z', + 'a','b','c','d','e','f','g','h','i','j','k','l','m', + 'n','o','p','q','r','s','t','u','v','w','x','y','z', + '0','1','2','3','4','5','6','7','8','9','+','/' +}; + +unsigned char pr2six[256]; + +int uuencode(unsigned char *bufin, unsigned int nbytes, char *bufcoded) +{ + /* ENC is the basic 1 character encoding function to make a char printing */ +#define ENC(c) six2pr[c] + + register char *outptr = bufcoded; + unsigned int i; + + for (i=0; i> 2); /* c1 */ + *(outptr++) = ENC(((*bufin << 4) & 060) | ((bufin[1] >> 4) & 017)); /*c2*/ + *(outptr++) = ENC(((bufin[1] << 2) & 074) | ((bufin[2] >> 6) & 03));/*c3*/ + *(outptr++) = ENC(bufin[2] & 077); /* c4 */ + bufin += 3; + } + if (i == nbytes+1) { + outptr[-1] = '='; + } else if (i == nbytes+2) { + outptr[-1] = '='; + outptr[-2] = '='; + } + *outptr = '\0'; + return(outptr - bufcoded); +} + +int uudecode(const char *bufcoded, unsigned char *bufplain, int outbufsize) +{ + /* single character decode */ +#define DEC(c) pr2six[(unsigned char)c] +#define MAXVAL 63 + + static int first = 1; + int nbytesdecoded, j; + const char *bufin = bufcoded; + register unsigned char *bufout = bufplain; + register int nprbytes; + + /* If this is the first call, initialize the mapping table. */ + if (first) { + first = 0; + for(j=0; j<256; j++) pr2six[j] = MAXVAL+1; + for(j=0; j<64; j++) pr2six[(unsigned char)six2pr[j]] = (unsigned char)j; + } + + /* Strip leading whitespace. */ + while (*bufcoded==' ' || *bufcoded == '\t') bufcoded++; + + /* Figure out how many characters are in the input buffer. + If this would decode into more bytes than would fit into + the output buffer, adjust the number of input bytes downwards. */ + bufin = bufcoded; + while (DEC(*(bufin++)) <= MAXVAL); + nprbytes = bufin - bufcoded - 1; + nbytesdecoded = ((nprbytes+3)/4) * 3; + if (nbytesdecoded > outbufsize) + nprbytes = (outbufsize*4)/3; + + bufin = bufcoded; + + while (nprbytes > 0) { + *(bufout++) = (unsigned char) (DEC(*bufin) << 2 | DEC(bufin[1]) >> 4); + *(bufout++) = (unsigned char) (DEC(bufin[1]) << 4 | DEC(bufin[2]) >> 2); + *(bufout++) = (unsigned char) (DEC(bufin[2]) << 6 | DEC(bufin[3])); + bufin += 4; + nprbytes -= 4; + } + if (nprbytes & 03) { + if (DEC(bufin[-2]) > MAXVAL) + nbytesdecoded -= 2; + else + nbytesdecoded -= 1; + } + return(nbytesdecoded); +} + +typedef unsigned char my_u_char; +typedef unsigned int my_u_int32_t; +typedef unsigned short my_u_short; + +/* Nasty macros from BIND-4.9.2 */ + +#define GETSHORT(s, cp) { \ + register my_u_char *t_cp = (my_u_char*)(cp); \ + (s) = (((my_u_short)t_cp[0]) << 8) \ + | (((my_u_short)t_cp[1])) \ + ; \ + (cp) += 2; \ +} + +#define GETLONG(l, cp) { \ + register my_u_char *t_cp = (my_u_char*)(cp); \ + (l) = (((my_u_int32_t)t_cp[0]) << 24) \ + | (((my_u_int32_t)t_cp[1]) << 16) \ + | (((my_u_int32_t)t_cp[2]) << 8) \ + | (((my_u_int32_t)t_cp[3])) \ + ; \ + (cp) += 4; \ +} + +#define PUTSHORT(s, cp) { \ + register my_u_short t_s = (my_u_short)(s); \ + register my_u_char *t_cp = (my_u_char*)(cp); \ + *t_cp++ = t_s >> 8; \ + *t_cp = t_s; \ + (cp) += 2; \ +} + +#define PUTLONG(l, cp) { \ + register my_u_int32_t t_l = (my_u_int32_t)(l); \ + register my_u_char *t_cp = (my_u_char*)(cp); \ + *t_cp++ = t_l >> 24; \ + *t_cp++ = t_l >> 16; \ + *t_cp++ = t_l >> 8; \ + *t_cp = t_l; \ + (cp) += 4; \ +} + +#define GETSTRING(s, p, p_l) { \ + register char* p_targ = (p) + p_l; \ + register char* s_c = (s); \ + register char* p_c = (p); \ + while (*p_c && (p_c < p_targ)) { \ + *s_c++ = *p_c++; \ + } \ + if (p_c == p_targ) { \ + return 1; \ + } \ + *s_c = *p_c++; \ + (p_l) = (p_l) - (p_c - (p)); \ + (p) = p_c; \ +} + + +int creds_to_radix(CREDENTIALS *creds, unsigned char *buf) +{ + char *p, *s; + int len; + char temp[2048]; + + p = temp; + *p++ = 1; /* version */ + s = creds->service; while (*s) *p++ = *s++; *p++ = *s; + s = creds->instance; while (*s) *p++ = *s++; *p++ = *s; + s = creds->realm; while (*s) *p++ = *s++; *p++ = *s; + + s = creds->pname; while (*s) *p++ = *s++; *p++ = *s; + s = creds->pinst; while (*s) *p++ = *s++; *p++ = *s; + /* Null string to repeat the realm. */ + *p++ = '\0'; + + PUTLONG(creds->issue_date,p); + { + unsigned int endTime ; + endTime = (unsigned int)krb_life_to_time(creds->issue_date, + creds->lifetime); + PUTLONG(endTime,p); + } + + memcpy(p,&creds->session, sizeof(creds->session)); + p += sizeof(creds->session); + + PUTSHORT(creds->kvno,p); + PUTLONG(creds->ticket_st.length,p); + + memcpy(p,creds->ticket_st.dat, creds->ticket_st.length); + p += creds->ticket_st.length; + len = p - temp; + + return(uuencode(temp, len, buf)); +} + +int radix_to_creds(const char *buf, CREDENTIALS *creds) +{ + + char *p; + int len, tl; + char version; + char temp[2048]; + + if (!(len = uudecode(buf, temp, sizeof(temp)))) + return 0; + + p = temp; + + /* check version and length! */ + if (len < 1) return 0; + version = *p; p++; len--; + + GETSTRING(creds->service, p, len); + GETSTRING(creds->instance, p, len); + GETSTRING(creds->realm, p, len); + + GETSTRING(creds->pname, p, len); + GETSTRING(creds->pinst, p, len); + /* Ignore possibly different realm. */ + while (*p && len) p++, len--; + if (len == 0) return 0; + p++, len--; + + /* Enough space for remaining fixed-length parts? */ + if (len < (4 + 4 + sizeof(creds->session) + 2 + 4)) + return 0; + + GETLONG(creds->issue_date,p); + len -= 4; + { + unsigned int endTime; + GETLONG(endTime,p); + len -= 4; + creds->lifetime = krb_time_to_life(creds->issue_date, endTime); + } + + memcpy(&creds->session, p, sizeof(creds->session)); + p += sizeof(creds->session); + len -= sizeof(creds->session); + + GETSHORT(creds->kvno,p); + len -= 2; + GETLONG(creds->ticket_st.length,p); + len -= 4; + + tl = creds->ticket_st.length; + if (tl < 0 || tl > len || tl > sizeof(creds->ticket_st.dat)) + return 0; + + memcpy(creds->ticket_st.dat, p, tl); + p += tl; + len -= tl; + + return 1; +} + +#endif /* AFS */ diff --git a/rc4.c b/rc4.c new file mode 100644 index 00000000..c126d206 --- /dev/null +++ b/rc4.c @@ -0,0 +1,105 @@ +/*! \file rc4.c + \brief Source file for RC4 stream cipher routines + \author Damien Miller + \version 0.0.0 + \date 1999 + + A simple implementation of the RC4 stream cipher, based on the + description given in _Bruce Schneier's_ "Applied Cryptography" + 2nd edition. + + Copyright 1999 Damien Miller + + Permission is hereby granted, free of charge, to any person + obtaining a copy of this software and associated documentation + files (the "Software"), to deal in the Software without + restriction, including without limitation the rights to use, copy, + modify, merge, publish, distribute, sublicense, and/or sell copies + of the Software, and to permit persons to whom the Software is + furnished to do so, subject to the following conditions: + + The above copyright notice and this permission notice shall be + included in all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY + KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE + WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE + AND NONINFRINGEMENT. IN NO EVENT SHALL DAMIEN MILLER BE LIABLE + FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF + CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION + WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + + \warning None of these functions clears its memory after use. It + \warning is the responsability of the calling routines to ensure + \warning that any sensitive data (keystream, key or plaintext) is + \warning properly erased after use. + + \warning The name "RC4" is trademarked in the United States, + \warning you may need to use "RC4 compatible" or "ARC4" + \warning (Alleged RC4). +*/ + +/* $Id$ */ + +#include "rc4.h" + + +void rc4_key(rc4_t *r, unsigned char *key, int len) +{ + int t; + + for(r->i = 0; r->i < 256; r->i++) + r->s[r->i] = r->i; + + r->j = 0; + for(r->i = 0; r->i < 256; r->i++) + { + r->j = (r->j + r->s[r->i] + key[r->i % len]) % 256; + t = r->s[r->i]; + r->s[r->i] = r->s[r->j]; + r->s[r->j] = t; + } + r->i = r->j = 0; +} + +void rc4_crypt(rc4_t *r, unsigned char *plaintext, int len) +{ + int t; + int c; + + c = 0; + while(c < len) + { + r->i = (r->i + 1) % 256; + r->j = (r->j + r->s[r->i]) % 256; + t = r->s[r->i]; + r->s[r->i] = r->s[r->j]; + r->s[r->j] = t; + + t = (r->s[r->i] + r->s[r->j]) % 256; + + plaintext[c] ^= r->s[t]; + c++; + } +} + +void rc4_getbytes(rc4_t *r, unsigned char *buffer, int len) +{ + int t; + int c; + + c = 0; + while(c < len) + { + r->i = (r->i + 1) % 256; + r->j = (r->j + r->s[r->i]) % 256; + t = r->s[r->i]; + r->s[r->i] = r->s[r->j]; + r->s[r->j] = t; + + t = (r->s[r->i] + r->s[r->j]) % 256; + + buffer[c] = r->s[t]; + c++; + } +} diff --git a/rc4.h b/rc4.h new file mode 100644 index 00000000..021010d8 --- /dev/null +++ b/rc4.h @@ -0,0 +1,110 @@ +/*! \file rc4.h + \brief Header file for RC4 stream cipher routines + \author Damien Miller + \version 0.0.0 + \date 1999 + + A simple implementation of the RC4 stream cipher, based on the + description given in _Bruce Schneier's_ "Applied Cryptography" + 2nd edition. + + Copyright 1999 Damien Miller + + Permission is hereby granted, free of charge, to any person + obtaining a copy of this software and associated documentation + files (the "Software"), to deal in the Software without + restriction, including without limitation the rights to use, copy, + modify, merge, publish, distribute, sublicense, and/or sell copies + of the Software, and to permit persons to whom the Software is + furnished to do so, subject to the following conditions: + + The above copyright notice and this permission notice shall be + included in all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY + KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE + WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE + AND NONINFRINGEMENT. IN NO EVENT SHALL DAMIEN MILLER BE LIABLE + FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF + CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION + WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + + \warning None of these functions clears its memory after use. It + \warning is the responsability of the calling routines to ensure + \warning that any sensitive data (keystream, key or plaintext) is + \warning properly erased after use. + + \warning The name "RC4" is trademarked in the United States, + \warning you may need to use "RC4 compatible" or "ARC4" + \warning (Alleged RC4). +*/ + +/* $Id$ */ + +#ifndef _RC4_H +#define _RC4_H + +/*! \struct rc4_t + \brief RC4 stream cipher state object + \var s State array + \var i Monotonic index + \var j Randomised index + + \warning This structure should not be accessed directly. To + \warning initialise a rc4_t object, you should use the rc4_key() + \warning function + + This structure holds the current state of the RC4 algorithm. +*/ +typedef struct +{ + unsigned int s[256]; + int i; + int j; +} rc4_t; + +/*! \fn void rc4_key(rc4_t *r, unsigned char *key, int len); + \brief Set up key structure of RC4 stream cipher + \param r pointer to RC4 structure to be seeded + \param key pointer to buffer containing raw key + \param len length of key + + This function set the internal state of the RC4 data structure + pointed to by \a r using the specified \a key of length \a len. + + This function can use up to 256 bytes of key, any more are ignored. + + \warning Stream ciphers (such as RC4) can be insecure if the same + \warning key is used repeatedly. Ensure that any key specified has + \warning an reasonably sized Initialisation Vector component. +*/ +void rc4_key(rc4_t *r, unsigned char *key, int len); + +/*! \fn rc4_crypt(rc4_t *r, unsigned char *plaintext, int len); + \brief Crypt bytes using RC4 algorithm + \param r pointer to RC4 structure to be used + \param plaintext Pointer to bytes to encrypt + \param len number of bytes to crypt + + This function encrypts one or more bytes (pointed to by \a plaintext) + using the RC4 algorithm. \a r is a state structure that must be + initialiased using the rc4_key() function prior to use. + + Since RC4 XORs each byte of plaintext with a byte of keystream, + this function can be used for both encryption and decryption. +*/ +void rc4_crypt(rc4_t *r, unsigned char *plaintext, int len); + +/*! \fn rc4_getbytes(rc4_t *r, unsigned char *buffer, int len); + \brief Generate key stream using the RC4 stream cipher + \param r pointer to RC4 structure to be used + \param buffer pointer to buffer in which to deposit keystream + \param len number of bytes to deposit + + This function gives access to the raw RC4 key stream. In this + consiguration RC4 can be used as a fast, strong pseudo-random + number generator with a very long period. +*/ +void rc4_getbytes(rc4_t *r, unsigned char *buffer, int len); + +#endif /* _RC4_H */ diff --git a/readconf.c b/readconf.c new file mode 100644 index 00000000..50f29261 --- /dev/null +++ b/readconf.c @@ -0,0 +1,684 @@ +/* + +readconf.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Apr 22 00:03:10 1995 ylo + +Functions for reading the configuration files. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include "cipher.h" +#include "readconf.h" +#include "xmalloc.h" + +/* Format of the configuration file: + + # Configuration data is parsed as follows: + # 1. command line options + # 2. user-specific file + # 3. system-wide file + # Any configuration value is only changed the first time it is set. + # Thus, host-specific definitions should be at the beginning of the + # configuration file, and defaults at the end. + + # Host-specific declarations. These may override anything above. A single + # host may match multiple declarations; these are processed in the order + # that they are given in. + + Host *.ngs.fi ngs.fi + FallBackToRsh no + + Host fake.com + HostName another.host.name.real.org + User blaah + Port 34289 + ForwardX11 no + ForwardAgent no + + Host books.com + RemoteForward 9999 shadows.cs.hut.fi:9999 + Cipher 3des + + Host fascist.blob.com + Port 23123 + User tylonen + RhostsAuthentication no + PasswordAuthentication no + + Host puukko.hut.fi + User t35124p + ProxyCommand ssh-proxy %h %p + + Host *.fr + UseRsh yes + + Host *.su + Cipher none + PasswordAuthentication no + + # Defaults for various options + Host * + ForwardAgent no + ForwardX11 yes + RhostsAuthentication yes + PasswordAuthentication yes + RSAAuthentication yes + RhostsRSAAuthentication yes + FallBackToRsh no + UseRsh no + StrictHostKeyChecking yes + KeepAlives no + IdentityFile ~/.ssh/identity + Port 22 + EscapeChar ~ + +*/ + +/* Keyword tokens. */ + +typedef enum +{ + oForwardAgent, oForwardX11, oGatewayPorts, oRhostsAuthentication, + oPasswordAuthentication, oRSAAuthentication, oFallBackToRsh, oUseRsh, +#ifdef KRB4 + oKerberosAuthentication, +#endif /* KRB4 */ +#ifdef AFS + oKerberosTgtPassing, oAFSTokenPassing, +#endif + oIdentityFile, oHostName, oPort, oCipher, oRemoteForward, oLocalForward, + oUser, oHost, oEscapeChar, oRhostsRSAAuthentication, oProxyCommand, + oGlobalKnownHostsFile, oUserKnownHostsFile, oConnectionAttempts, + oBatchMode, oCheckHostIP, oStrictHostKeyChecking, oCompression, + oCompressionLevel, oKeepAlives, oNumberOfPasswordPrompts, oTISAuthentication, + oUsePrivilegedPort +} OpCodes; + +/* Textual representations of the tokens. */ + +static struct +{ + const char *name; + OpCodes opcode; +} keywords[] = +{ + { "forwardagent", oForwardAgent }, + { "forwardx11", oForwardX11 }, + { "gatewayports", oGatewayPorts }, + { "useprivilegedport", oUsePrivilegedPort }, + { "rhostsauthentication", oRhostsAuthentication }, + { "passwordauthentication", oPasswordAuthentication }, + { "rsaauthentication", oRSAAuthentication }, +#ifdef KRB4 + { "kerberosauthentication", oKerberosAuthentication }, +#endif /* KRB4 */ +#ifdef AFS + { "kerberostgtpassing", oKerberosTgtPassing }, + { "afstokenpassing", oAFSTokenPassing }, +#endif + { "fallbacktorsh", oFallBackToRsh }, + { "usersh", oUseRsh }, + { "identityfile", oIdentityFile }, + { "hostname", oHostName }, + { "proxycommand", oProxyCommand }, + { "port", oPort }, + { "cipher", oCipher }, + { "remoteforward", oRemoteForward }, + { "localforward", oLocalForward }, + { "user", oUser }, + { "host", oHost }, + { "escapechar", oEscapeChar }, + { "rhostsrsaauthentication", oRhostsRSAAuthentication }, + { "globalknownhostsfile", oGlobalKnownHostsFile }, + { "userknownhostsfile", oUserKnownHostsFile }, + { "connectionattempts", oConnectionAttempts }, + { "batchmode", oBatchMode }, + { "checkhostip", oCheckHostIP }, + { "stricthostkeychecking", oStrictHostKeyChecking }, + { "compression", oCompression }, + { "compressionlevel", oCompressionLevel }, + { "keepalive", oKeepAlives }, + { "numberofpasswordprompts", oNumberOfPasswordPrompts }, + { "tisauthentication", oTISAuthentication }, + { NULL, 0 } +}; + +/* Characters considered whitespace in strtok calls. */ +#define WHITESPACE " \t\r\n" + + +/* Adds a local TCP/IP port forward to options. Never returns if there + is an error. */ + +void add_local_forward(Options *options, int port, const char *host, + int host_port) +{ + Forward *fwd; + extern uid_t original_real_uid; + if ((port & 0xffff) != port) + fatal("Requested forwarding of nonexistent port %d.", port); + if (port < IPPORT_RESERVED && original_real_uid != 0) + fatal("Privileged ports can only be forwarded by root.\n"); + if (options->num_local_forwards >= SSH_MAX_FORWARDS_PER_DIRECTION) + fatal("Too many local forwards (max %d).", SSH_MAX_FORWARDS_PER_DIRECTION); + fwd = &options->local_forwards[options->num_local_forwards++]; + fwd->port = port; + fwd->host = xstrdup(host); + fwd->host_port = host_port; +} + +/* Adds a remote TCP/IP port forward to options. Never returns if there + is an error. */ + +void add_remote_forward(Options *options, int port, const char *host, + int host_port) +{ + Forward *fwd; + if (options->num_remote_forwards >= SSH_MAX_FORWARDS_PER_DIRECTION) + fatal("Too many remote forwards (max %d).", + SSH_MAX_FORWARDS_PER_DIRECTION); + fwd = &options->remote_forwards[options->num_remote_forwards++]; + fwd->port = port; + fwd->host = xstrdup(host); + fwd->host_port = host_port; +} + +/* Returns the number of the token pointed to by cp of length len. + Never returns if the token is not known. */ + +static OpCodes parse_token(const char *cp, const char *filename, int linenum) +{ + unsigned int i; + + for (i = 0; keywords[i].name; i++) + if (strcmp(cp, keywords[i].name) == 0) + return keywords[i].opcode; + + fatal("%.200s line %d: Bad configuration option.", + filename, linenum); + /*NOTREACHED*/ + return 0; +} + +/* Processes a single option line as used in the configuration files. + This only sets those values that have not already been set. */ + +void process_config_line(Options *options, const char *host, + char *line, const char *filename, int linenum, + int *activep) +{ + char buf[256], *cp, *string, **charptr; + int opcode, *intptr, value, fwd_port, fwd_host_port; + + /* Skip leading whitespace. */ + cp = line + strspn(line, WHITESPACE); + if (!*cp || *cp == '\n' || *cp == '#') + return; + + /* Get the keyword. (Each line is supposed to begin with a keyword). */ + cp = strtok(cp, WHITESPACE); + { + char *t = cp; + for (; *t != 0; t++) + if ('A' <= *t && *t <= 'Z') + *t = *t - 'A' + 'a'; /* tolower */ + + } + opcode = parse_token(cp, filename, linenum); + + switch (opcode) + { + + case oForwardAgent: + intptr = &options->forward_agent; + parse_flag: + cp = strtok(NULL, WHITESPACE); + if (!cp) + fatal("%.200s line %d: Missing yes/no argument.", filename, linenum); + value = 0; /* To avoid compiler warning... */ + if (strcmp(cp, "yes") == 0 || strcmp(cp, "true") == 0) + value = 1; + else if (strcmp(cp, "no") == 0 || strcmp(cp, "false") == 0) + value = 0; + else + fatal("%.200s line %d: Bad yes/no argument.", filename, linenum); + if (*activep && *intptr == -1) + *intptr = value; + break; + + case oForwardX11: + intptr = &options->forward_x11; + goto parse_flag; + + case oGatewayPorts: + intptr = &options->gateway_ports; + goto parse_flag; + + case oUsePrivilegedPort: + intptr = &options->use_privileged_port; + goto parse_flag; + + case oRhostsAuthentication: + intptr = &options->rhosts_authentication; + goto parse_flag; + + case oPasswordAuthentication: + intptr = &options->password_authentication; + goto parse_flag; + + case oRSAAuthentication: + intptr = &options->rsa_authentication; + goto parse_flag; + + case oRhostsRSAAuthentication: + intptr = &options->rhosts_rsa_authentication; + goto parse_flag; + +#ifdef KRB4 + case oKerberosAuthentication: + intptr = &options->kerberos_authentication; + goto parse_flag; +#endif /* KRB4 */ + +#ifdef AFS + case oKerberosTgtPassing: + intptr = &options->kerberos_tgt_passing; + goto parse_flag; + + case oAFSTokenPassing: + intptr = &options->afs_token_passing; + goto parse_flag; +#endif + + case oFallBackToRsh: + intptr = &options->fallback_to_rsh; + goto parse_flag; + + case oUseRsh: + intptr = &options->use_rsh; + goto parse_flag; + + case oBatchMode: + intptr = &options->batch_mode; + goto parse_flag; + + case oCheckHostIP: + intptr = &options->check_host_ip; + goto parse_flag; + + case oStrictHostKeyChecking: + intptr = &options->strict_host_key_checking; + cp = strtok(NULL, WHITESPACE); + if (!cp) + fatal("%.200s line %d: Missing yes/no argument.", + filename, linenum); + value = 0; /* To avoid compiler warning... */ + if (strcmp(cp, "yes") == 0 || strcmp(cp, "true") == 0) + value = 1; + else if (strcmp(cp, "no") == 0 || strcmp(cp, "false") == 0) + value = 0; + else if (strcmp(cp, "ask") == 0) + value = 2; + else + fatal("%.200s line %d: Bad yes/no/ask argument.", filename, linenum); + if (*activep && *intptr == -1) + *intptr = value; + break; + + case oCompression: + intptr = &options->compression; + goto parse_flag; + + case oKeepAlives: + intptr = &options->keepalives; + goto parse_flag; + + case oNumberOfPasswordPrompts: + intptr = &options->number_of_password_prompts; + goto parse_int; + + case oTISAuthentication: + cp = strtok(NULL, WHITESPACE); + if (cp != 0 && (strcmp(cp, "yes") == 0 || strcmp(cp, "true") == 0)) + fprintf(stderr, + "%.99s line %d: Warning, TIS is not supported.\n", + filename, + linenum); + break; + + case oCompressionLevel: + intptr = &options->compression_level; + goto parse_int; + + case oIdentityFile: + cp = strtok(NULL, WHITESPACE); + if (!cp) + fatal("%.200s line %d: Missing argument.", filename, linenum); + if (*activep) + { + if (options->num_identity_files >= SSH_MAX_IDENTITY_FILES) + fatal("%.200s line %d: Too many identity files specified (max %d).", + filename, linenum, SSH_MAX_IDENTITY_FILES); + options->identity_files[options->num_identity_files++] = xstrdup(cp); + } + break; + + case oUser: + charptr = &options->user; + parse_string: + cp = strtok(NULL, WHITESPACE); + if (!cp) + fatal("%.200s line %d: Missing argument.", filename, linenum); + if (*activep && *charptr == NULL) + *charptr = xstrdup(cp); + break; + + case oGlobalKnownHostsFile: + charptr = &options->system_hostfile; + goto parse_string; + + case oUserKnownHostsFile: + charptr = &options->user_hostfile; + goto parse_string; + + case oHostName: + charptr = &options->hostname; + goto parse_string; + + case oProxyCommand: + charptr = &options->proxy_command; + string = xstrdup(""); + while ((cp = strtok(NULL, WHITESPACE)) != NULL) + { + string = xrealloc(string, strlen(string) + strlen(cp) + 2); + strcat(string, " "); + strcat(string, cp); + } + if (*activep && *charptr == NULL) + *charptr = string; + else + xfree(string); + return; + + case oPort: + intptr = &options->port; + parse_int: + cp = strtok(NULL, WHITESPACE); + if (!cp) + fatal("%.200s line %d: Missing argument.", filename, linenum); + if (cp[0] < '0' || cp[0] > '9') + fatal("%.200s line %d: Bad number.", filename, linenum); +#if 0 + value = atoi(cp); +#else + { + char *ptr; + value = strtol(cp, &ptr, 0); /* Octal, decimal, or hex format? */ + if (cp == ptr) + fatal("%.200s line %d: Bad number.", filename, linenum); + } +#endif + if (*activep && *intptr == -1) + *intptr = value; + break; + + case oConnectionAttempts: + intptr = &options->connection_attempts; + goto parse_int; + + case oCipher: + intptr = &options->cipher; + cp = strtok(NULL, WHITESPACE); + value = cipher_number(cp); + if (value == -1) + fatal("%.200s line %d: Bad cipher.", filename, linenum); + if (*activep && *intptr == -1) + *intptr = value; + break; + + case oRemoteForward: + cp = strtok(NULL, WHITESPACE); + if (!cp) + fatal("%.200s line %d: Missing argument.", filename, linenum); + if (cp[0] < '0' || cp[0] > '9') + fatal("%.200s line %d: Badly formatted port number.", + filename, linenum); + fwd_port = atoi(cp); + cp = strtok(NULL, WHITESPACE); + if (!cp) + fatal("%.200s line %d: Missing second argument.", + filename, linenum); + if (sscanf(cp, "%255[^:]:%d", buf, &fwd_host_port) != 2) + fatal("%.200s line %d: Badly formatted host:port.", + filename, linenum); + if (*activep) + add_remote_forward(options, fwd_port, buf, fwd_host_port); + break; + + case oLocalForward: + cp = strtok(NULL, WHITESPACE); + if (!cp) + fatal("%.200s line %d: Missing argument.", filename, linenum); + if (cp[0] < '0' || cp[0] > '9') + fatal("%.200s line %d: Badly formatted port number.", + filename, linenum); + fwd_port = atoi(cp); + cp = strtok(NULL, WHITESPACE); + if (!cp) + fatal("%.200s line %d: Missing second argument.", + filename, linenum); + if (sscanf(cp, "%255[^:]:%d", buf, &fwd_host_port) != 2) + fatal("%.200s line %d: Badly formatted host:port.", + filename, linenum); + if (*activep) + add_local_forward(options, fwd_port, buf, fwd_host_port); + break; + + case oHost: + *activep = 0; + while ((cp = strtok(NULL, WHITESPACE)) != NULL) + if (match_pattern(host, cp)) + { + debug("Applying options for %.100s", cp); + *activep = 1; + break; + } + /* Avoid garbage check below, as strtok already returned NULL. */ + return; + + case oEscapeChar: + intptr = &options->escape_char; + cp = strtok(NULL, WHITESPACE); + if (!cp) + fatal("%.200s line %d: Missing argument.", filename, linenum); + if (cp[0] == '^' && cp[2] == 0 && + (unsigned char)cp[1] >= 64 && (unsigned char)cp[1] < 128) + value = (unsigned char)cp[1] & 31; + else + if (strlen(cp) == 1) + value = (unsigned char)cp[0]; + else + if (strcmp(cp, "none") == 0) + value = -2; + else + { + fatal("%.200s line %d: Bad escape character.", + filename, linenum); + /*NOTREACHED*/ + value = 0; /* Avoid compiler warning. */ + } + if (*activep && *intptr == -1) + *intptr = value; + break; + + default: + fatal("parse_config_file: Unimplemented opcode %d", opcode); + } + + /* Check that there is no garbage at end of line. */ + if (strtok(NULL, WHITESPACE) != NULL) + fatal("%.200s line %d: garbage at end of line.", + filename, linenum); +} + + +/* Reads the config file and modifies the options accordingly. Options should + already be initialized before this call. This never returns if there + is an error. If the file does not exist, this returns immediately. */ + +void read_config_file(const char *filename, const char *host, Options *options) +{ + FILE *f; + char line[1024]; + int active, linenum; + + /* Open the file. */ + f = fopen(filename, "r"); + if (!f) + return; + + debug("Reading configuration data %.200s", filename); + + /* Mark that we are now processing the options. This flag is turned on/off + by Host specifications. */ + active = 1; + linenum = 0; + while (fgets(line, sizeof(line), f)) + { + /* Update line number counter. */ + linenum++; + + process_config_line(options, host, line, filename, linenum, &active); + } + fclose(f); +} + +/* Initializes options to special values that indicate that they have not + yet been set. Read_config_file will only set options with this value. + Options are processed in the following order: command line, user config + file, system config file. Last, fill_default_options is called. */ + +void initialize_options(Options *options) +{ + memset(options, 'X', sizeof(*options)); + options->forward_agent = -1; + options->forward_x11 = -1; + options->gateway_ports = -1; + options->use_privileged_port = -1; + options->rhosts_authentication = -1; + options->rsa_authentication = -1; +#ifdef KRB4 + options->kerberos_authentication = -1; +#endif +#ifdef AFS + options->kerberos_tgt_passing = -1; + options->afs_token_passing = -1; +#endif + options->password_authentication = -1; + options->rhosts_rsa_authentication = -1; + options->fallback_to_rsh = -1; + options->use_rsh = -1; + options->batch_mode = -1; + options->check_host_ip = -1; + options->strict_host_key_checking = -1; + options->compression = -1; + options->keepalives = -1; + options->compression_level = -1; + options->port = -1; + options->connection_attempts = -1; + options->number_of_password_prompts = -1; + options->cipher = -1; + options->num_identity_files = 0; + options->hostname = NULL; + options->proxy_command = NULL; + options->user = NULL; + options->escape_char = -1; + options->system_hostfile = NULL; + options->user_hostfile = NULL; + options->num_local_forwards = 0; + options->num_remote_forwards = 0; +} + +/* Called after processing other sources of option data, this fills those + options for which no value has been specified with their default values. */ + +void fill_default_options(Options *options) +{ + if (options->forward_agent == -1) + options->forward_agent = 1; + if (options->forward_x11 == -1) + options->forward_x11 = 1; + if (options->gateway_ports == -1) + options->gateway_ports = 0; + if (options->use_privileged_port == -1) + options->use_privileged_port = 1; + if (options->rhosts_authentication == -1) + options->rhosts_authentication = 1; + if (options->rsa_authentication == -1) + options->rsa_authentication = 1; +#ifdef KRB4 + if (options->kerberos_authentication == -1) + options->kerberos_authentication = 1; +#endif /* KRB4 */ +#ifdef AFS + if (options->kerberos_tgt_passing == -1) + options->kerberos_tgt_passing = 1; + if (options->afs_token_passing == -1) + options->afs_token_passing = 1; +#endif /* AFS */ + if (options->password_authentication == -1) + options->password_authentication = 1; + if (options->rhosts_rsa_authentication == -1) + options->rhosts_rsa_authentication = 1; + if (options->fallback_to_rsh == -1) + options->fallback_to_rsh = 1; + if (options->use_rsh == -1) + options->use_rsh = 0; + if (options->batch_mode == -1) + options->batch_mode = 0; + if (options->check_host_ip == -1) + options->check_host_ip = 1; + if (options->strict_host_key_checking == -1) + options->strict_host_key_checking = 2; /* 2 is default */ + if (options->compression == -1) + options->compression = 0; + if (options->keepalives == -1) + options->keepalives = 1; + if (options->compression_level == -1) + options->compression_level = 6; + if (options->port == -1) + options->port = 0; /* Filled in ssh_connect. */ + if (options->connection_attempts == -1) + options->connection_attempts = 4; + if (options->number_of_password_prompts == -1) + options->number_of_password_prompts = 3; + if (options->cipher == -1) + options->cipher = SSH_CIPHER_NOT_SET; /* Selected in ssh_login(). */ + if (options->num_identity_files == 0) + { + options->identity_files[0] = + xmalloc(2 + strlen(SSH_CLIENT_IDENTITY) + 1); + sprintf(options->identity_files[0], "~/%.100s", SSH_CLIENT_IDENTITY); + options->num_identity_files = 1; + } + if (options->escape_char == -1) + options->escape_char = '~'; + if (options->system_hostfile == NULL) + options->system_hostfile = SSH_SYSTEM_HOSTFILE; + if (options->user_hostfile == NULL) + options->user_hostfile = SSH_USER_HOSTFILE; + /* options->proxy_command should not be set by default */ + /* options->user will be set in the main program if appropriate */ + /* options->hostname will be set in the main program if appropriate */ +} + diff --git a/readconf.h b/readconf.h new file mode 100644 index 00000000..25d02e65 --- /dev/null +++ b/readconf.h @@ -0,0 +1,116 @@ +/* + +readconf.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Apr 22 00:25:29 1995 ylo + +Functions for reading the configuration file. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef READCONF_H +#define READCONF_H + +/* Data structure for representing a forwarding request. */ + +typedef struct +{ + int port; /* Port to forward. */ + char *host; /* Host to connect. */ + int host_port; /* Port to connect on host. */ +} Forward; + +/* Data structure for representing option data. */ + +typedef struct +{ + int forward_agent; /* Forward authentication agent. */ + int forward_x11; /* Forward X11 display. */ + int gateway_ports; /* Allow remote connects to forwarded ports. */ + int use_privileged_port; /* Don't use privileged port if false. */ + int rhosts_authentication; /* Try rhosts authentication. */ + int rhosts_rsa_authentication;/* Try rhosts with RSA authentication. */ + int rsa_authentication; /* Try RSA authentication. */ +#ifdef KRB4 + int kerberos_authentication; /* Try Kerberos authentication. */ +#endif +#ifdef AFS + int kerberos_tgt_passing; /* Try Kerberos tgt passing. */ + int afs_token_passing; /* Try AFS token passing. */ +#endif + int password_authentication; /* Try password authentication. */ + int fallback_to_rsh; /* Use rsh if cannot connect with ssh. */ + int use_rsh; /* Always use rsh (don\'t try ssh). */ + int batch_mode; /* Batch mode: do not ask for passwords. */ + int check_host_ip; /* Also keep track of keys for IP address */ + int strict_host_key_checking; /* Strict host key checking. */ + int compression; /* Compress packets in both directions. */ + int compression_level; /* Compression level 1 (fast) to 9 (best). */ + int keepalives; /* Set SO_KEEPALIVE. */ + + int port; /* Port to connect. */ + int connection_attempts; /* Max attempts (seconds) before giving up */ + int number_of_password_prompts; /* Max number of password prompts. */ + int cipher; /* Cipher to use. */ + char *hostname; /* Real host to connect. */ + char *proxy_command; /* Proxy command for connecting the host. */ + char *user; /* User to log in as. */ + int escape_char; /* Escape character; -2 = none */ + + char *system_hostfile; /* Path for /etc/ssh_known_hosts. */ + char *user_hostfile; /* Path for $HOME/.ssh/known_hosts. */ + + int num_identity_files; /* Number of files for RSA identities. */ + char *identity_files[SSH_MAX_IDENTITY_FILES]; + + /* Local TCP/IP forward requests. */ + int num_local_forwards; + Forward local_forwards[SSH_MAX_FORWARDS_PER_DIRECTION]; + + /* Remote TCP/IP forward requests. */ + int num_remote_forwards; + Forward remote_forwards[SSH_MAX_FORWARDS_PER_DIRECTION]; +} Options; + + +/* Initializes options to special values that indicate that they have not + yet been set. Read_config_file will only set options with this value. + Options are processed in the following order: command line, user config + file, system config file. Last, fill_default_options is called. */ +void initialize_options(Options *options); + +/* Called after processing other sources of option data, this fills those + options for which no value has been specified with their default values. */ +void fill_default_options(Options *options); + +/* Processes a single option line as used in the configuration files. + This only sets those values that have not already been set. */ +void process_config_line(Options *options, const char *host, + char *line, const char *filename, int linenum, + int *activep); + +/* Reads the config file and modifies the options accordingly. Options should + already be initialized before this call. This never returns if there + is an error. If the file does not exist, this returns immediately. */ +void read_config_file(const char *filename, const char *host, + Options *options); + +/* Adds a local TCP/IP port forward to options. Never returns if there + is an error. */ +void add_local_forward(Options *options, int port, const char *host, + int host_port); + +/* Adds a remote TCP/IP port forward to options. Never returns if there + is an error. */ +void add_remote_forward(Options *options, int port, const char *host, + int host_port); + + +#endif /* READCONF_H */ diff --git a/readpass.c b/readpass.c new file mode 100644 index 00000000..5c455755 --- /dev/null +++ b/readpass.c @@ -0,0 +1,114 @@ +/* + +readpass.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Mon Jul 10 22:08:59 1995 ylo + +Functions for reading passphrases and passwords. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "xmalloc.h" +#include "ssh.h" + +/* Saved old terminal mode for read_passphrase. */ +static struct termios saved_tio; + +/* Old interrupt signal handler for read_passphrase. */ +static void (*old_handler)(int sig) = NULL; + +/* Interrupt signal handler for read_passphrase. */ + +void intr_handler(int sig) +{ + /* Restore terminal modes. */ + tcsetattr(fileno(stdin), TCSANOW, &saved_tio); + /* Restore the old signal handler. */ + signal(sig, old_handler); + /* Resend the signal, with the old handler. */ + kill(getpid(), sig); +} + +/* Reads a passphrase from /dev/tty with echo turned off. Returns the + passphrase (allocated with xmalloc). Exits if EOF is encountered. + The passphrase if read from stdin if from_stdin is true (as is the + case with ssh-keygen). */ + +char *read_passphrase(const char *prompt, int from_stdin) +{ + char buf[1024], *cp; + struct termios tio; + FILE *f; + + if (from_stdin) + f = stdin; + else + { + /* Read the passphrase from /dev/tty to make it possible to ask it even + when stdin has been redirected. */ + f = fopen("/dev/tty", "r"); + if (!f) + { + /* No controlling terminal and no DISPLAY. Nowhere to read. */ + fprintf(stderr, "You have no controlling tty and no DISPLAY. Cannot read passphrase.\n"); + exit(1); + } + } + + /* Display the prompt (on stderr because stdout might be redirected). */ + fflush(stdout); + fprintf(stderr, "%s", prompt); + fflush(stderr); + + /* Get terminal modes. */ + tcgetattr(fileno(f), &tio); + saved_tio = tio; + /* Save signal handler and set the new handler. */ + old_handler = signal(SIGINT, intr_handler); + + /* Set new terminal modes disabling all echo. */ + tio.c_lflag &= ~(ECHO | ECHOE | ECHOK | ECHONL); + tcsetattr(fileno(f), TCSANOW, &tio); + + /* Read the passphrase from the terminal. */ + if (fgets(buf, sizeof(buf), f) == NULL) + { + /* Got EOF. Just exit. */ + /* Restore terminal modes. */ + tcsetattr(fileno(f), TCSANOW, &saved_tio); + /* Restore the signal handler. */ + signal(SIGINT, old_handler); + /* Print a newline (the prompt probably didn\'t have one). */ + fprintf(stderr, "\n"); + /* Close the file. */ + if (f != stdin) + fclose(f); + exit(1); + } + /* Restore terminal modes. */ + tcsetattr(fileno(f), TCSANOW, &saved_tio); + /* Restore the signal handler. */ + (void)signal(SIGINT, old_handler); + /* Remove newline from the passphrase. */ + if (strchr(buf, '\n')) + *strchr(buf, '\n') = 0; + /* Allocate a copy of the passphrase. */ + cp = xstrdup(buf); + /* Clear the buffer so we don\'t leave copies of the passphrase laying + around. */ + memset(buf, 0, sizeof(buf)); + /* Print a newline since the prompt probably didn\'t have one. */ + fprintf(stderr, "\n"); + /* Close the file. */ + if (f != stdin) + fclose(f); + return cp; +} diff --git a/rsa.c b/rsa.c new file mode 100644 index 00000000..d19e9686 --- /dev/null +++ b/rsa.c @@ -0,0 +1,164 @@ +/* + +rsa.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Fri Mar 3 22:07:06 1995 ylo + +Description of the RSA algorithm can be found e.g. from the following sources: + + Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1994. + + Jennifer Seberry and Josed Pieprzyk: Cryptography: An Introduction to + Computer Security. Prentice-Hall, 1989. + + Man Young Rhee: Cryptography and Secure Data Communications. McGraw-Hill, + 1994. + + R. Rivest, A. Shamir, and L. M. Adleman: Cryptographic Communications + System and Method. US Patent 4,405,829, 1983. + + Hans Riesel: Prime Numbers and Computer Methods for Factorization. + Birkhauser, 1994. + + The RSA Frequently Asked Questions document by RSA Data Security, Inc., 1995. + + RSA in 3 lines of perl by Adam Back , 1995, as included + below: + + gone - had to be deleted - what a pity + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "rsa.h" +#include "ssh.h" +#include "xmalloc.h" + +int rsa_verbose = 1; + +int +rsa_alive() +{ + RSA *key; + + key = RSA_generate_key(32, 3, NULL, NULL); + if (key == NULL) + return (0); + RSA_free(key); + return (1); +} + +/* Generates RSA public and private keys. This initializes the data + structures; they should be freed with rsa_clear_private_key and + rsa_clear_public_key. */ + +void +rsa_generate_key(RSA *prv, RSA *pub, unsigned int bits) +{ + RSA *key; + + if (rsa_verbose) { + printf("Generating RSA keys: "); + fflush(stdout); + } + + key = RSA_generate_key(bits, 35, NULL, NULL); + + assert(key != NULL); + + /* Copy public key parameters */ + pub->n = BN_new(); + BN_copy(pub->n, key->n); + pub->e = BN_new(); + BN_copy(pub->e, key->e); + + /* Copy private key parameters */ + prv->n = BN_new(); + BN_copy(prv->n, key->n); + prv->e = BN_new(); + BN_copy(prv->e, key->e); + prv->d = BN_new(); + BN_copy(prv->d, key->d); + prv->p = BN_new(); + BN_copy(prv->p, key->p); + prv->q = BN_new(); + BN_copy(prv->q, key->q); + + prv->dmp1 = BN_new(); + BN_copy(prv->dmp1, key->dmp1); + + prv->dmq1 = BN_new(); + BN_copy(prv->dmq1, key->dmq1); + + prv->iqmp = BN_new(); + BN_copy(prv->iqmp, key->iqmp); + + RSA_free(key); + + if (rsa_verbose) + printf("Key generation complete.\n"); +} + +void +rsa_public_encrypt(BIGNUM *out, BIGNUM *in, RSA* key) +{ + char *inbuf, *outbuf; + int len; + + if (BN_num_bits(key->e) < 2 || !BN_is_odd(key->e)) + fatal("rsa_public_encrypt() exponent too small or not odd"); + + len = BN_num_bytes(key->n); + outbuf = xmalloc(len); + + len = BN_num_bytes(in); + inbuf = xmalloc(len); + BN_bn2bin(in, inbuf); + + if ((len = RSA_public_encrypt(len, inbuf, outbuf, key, + RSA_PKCS1_PADDING)) <= 0) + fatal("rsa_public_encrypt() failed"); + + BN_bin2bn(outbuf, len, out); + + xfree(outbuf); + xfree(inbuf); +} + +void +rsa_private_decrypt(BIGNUM *out, BIGNUM *in, RSA *key) +{ + char *inbuf, *outbuf; + int len; + + len = BN_num_bytes(key->n); + outbuf = xmalloc(len); + + len = BN_num_bytes(in); + inbuf = xmalloc(len); + BN_bn2bin(in, inbuf); + + if ((len = RSA_private_decrypt(len, inbuf, outbuf, key, + RSA_SSLV23_PADDING)) <= 0) + fatal("rsa_private_decrypt() failed"); + + BN_bin2bn(outbuf, len, out); + + xfree(outbuf); + xfree(inbuf); +} + +/* Set whether to output verbose messages during key generation. */ + +void +rsa_set_verbose(int verbose) +{ + rsa_verbose = verbose; +} diff --git a/rsa.h b/rsa.h new file mode 100644 index 00000000..16704607 --- /dev/null +++ b/rsa.h @@ -0,0 +1,36 @@ +/* + +rsa.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Fri Mar 3 22:01:06 1995 ylo + +RSA key generation, encryption and decryption. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef RSA_H +#define RSA_H + +#include +#include + +/* Calls SSL RSA_generate_key, only copies to prv and pub */ +void rsa_generate_key(RSA *prv, RSA *pub, unsigned int bits); + +/* Indicates whether the rsa module is permitted to show messages on + the terminal. */ +void rsa_set_verbose __P((int verbose)); + +int rsa_alive __P((void)); + +void rsa_public_encrypt __P((BIGNUM *out, BIGNUM *in, RSA *prv)); +void rsa_private_decrypt __P((BIGNUM *out, BIGNUM *in, RSA *prv)); + +#endif /* RSA_H */ diff --git a/scp.1 b/scp.1 new file mode 100644 index 00000000..d8207664 --- /dev/null +++ b/scp.1 @@ -0,0 +1,110 @@ +.\" -*- nroff -*- +.\" +.\" scp.1 +.\" +.\" Author: Tatu Ylonen +.\" +.\" Copyright (c) 1995 Tatu Ylonen , Espoo, Finland +.\" All rights reserved +.\" +.\" Created: Sun May 7 00:14:37 1995 ylo +.\" +.\" $Id$ +.\" +.Dd September 25, 1999 +.Dt SCP 1 +.Os +.Sh NAME +.Nm scp +.Nd secure copy (remote file copy program) +.Sh SYNOPSIS +.Nm scp +.Op Fl pqrvC +.Op Fl P Ar port +.Op Fl c Ar cipher +.Op Fl i Ar identity_file +.Sm off +.Oo +.Op Ar user@ +.Ar host1 No : +.Oc Ns Ar file1 +.Sm on +.Op Ar ... +.Sm off +.Oo +.Op Ar user@ +.Ar host2 No : +.Oc Ar file2 +.Sm on +.Sh DESCRIPTION +.Nm +copies files between hosts on a network. It uses +.Xr ssh 1 +for data transfer, and uses the same authentication and provides the +same security as +.Xr ssh 1 . +Unlike +.Xr rcp 1 , +.Nm +will ask for passwords or passphrases if they are needed for +authentication. +.Pp +Any file name may contain a host and user specification to indicate +that the file is to be copied to/from that host. Copies between two +remote hosts are permitted. +.Pp +The options are as follows: +.Bl -tag -width Ds +.It Fl c Ar cipher +Selects the cipher to use for encrypting the data transfer. This +option is directly passed to +.Xr ssh 1 . +.It Fl i Ar identity_file +Selects the file from which the identity (private key) for RSA +authentication is read. This option is directly passed to +.Xr ssh 1 . +.It Fl p +Preserves modification times, access times, and modes from the +original file. +.It Fl r +Recursively copy entire directories. +.It Fl v +Verbose mode. Causes +.Nm +and +.Xr ssh 1 +to print debugging messages about their progress. This is helpful in +debugging connection, authentication, and configuration problems. +.It Fl B +Selects batch mode (prevents asking for passwords or passphrases). +.It Fl q +Disables the progress meter. +.It Fl C +Compression enable. Passes the +.Fl C +flag to +.Xr ssh 1 +to enable compression. +.It Fl P Ar port +Specifies the port to connect to on the remote host. Note that this +option is written with a capital +.Sq P , +because +.Fl p +is already reserved for preserving the times and modes of the file in +.Xr rcp 1 . +.Sh AUTHORS +Timo Rinne and Tatu Ylonen +.Sh HISTORY +.Nm +is based on the +.Xr rcp 1 +program in BSD source code from the Regents of the University of +California. +.Sh SEE ALSO +.Xr rcp 1 , +.Xr ssh 1 , +.Xr ssh-add 1 , +.Xr ssh-agent 1 , +.Xr ssh-keygen 1 , +.Xr sshd 8 diff --git a/scp.c b/scp.c new file mode 100644 index 00000000..8271e400 --- /dev/null +++ b/scp.c @@ -0,0 +1,1220 @@ +/* + +scp - secure remote copy. This is basically patched BSD rcp which uses ssh +to do the data transfer (instead of using rcmd). + +NOTE: This version should NOT be suid root. (This uses ssh to do the transfer +and ssh has the necessary privileges.) + +1995 Timo Rinne , Tatu Ylonen + +*/ + +/* + * Copyright (c) 1983, 1990, 1992, 1993, 1995 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $Id$ + */ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include "xmalloc.h" +#include + +#define _PATH_CP "cp" + +/* For progressmeter() -- number of seconds before xfer considered "stalled" */ +#define STALLTIME 5 + +/* Visual statistics about files as they are transferred. */ +void progressmeter(int); + +/* Returns width of the terminal (for progress meter calculations). */ +int getttywidth(void); + +/* Time a transfer started. */ +static struct timeval start; + +/* Number of bytes of current file transferred so far. */ +volatile unsigned long statbytes; + +/* Total size of current file. */ +unsigned long totalbytes = 0; + +/* Name of current file being transferred. */ +char *curfile; + +/* This is set to non-zero to enable verbose mode. */ +int verbose = 0; + +/* This is set to non-zero if compression is desired. */ +int compress = 0; + +/* This is set to zero if the progressmeter is not desired. */ +int showprogress = 1; + +/* This is set to non-zero if running in batch mode (that is, password + and passphrase queries are not allowed). */ +int batchmode = 0; + +/* This is set to the cipher type string if given on the command line. */ +char *cipher = NULL; + +/* This is set to the RSA authentication identity file name if given on + the command line. */ +char *identity = NULL; + +/* This is the port to use in contacting the remote site (is non-NULL). */ +char *port = NULL; + +/* This function executes the given command as the specified user on the given + host. This returns < 0 if execution fails, and >= 0 otherwise. + This assigns the input and output file descriptors on success. */ + +int do_cmd(char *host, char *remuser, char *cmd, int *fdin, int *fdout) +{ + int pin[2], pout[2], reserved[2]; + + if (verbose) + fprintf(stderr, "Executing: host %s, user %s, command %s\n", + host, remuser ? remuser : "(unspecified)", cmd); + + /* Reserve two descriptors so that the real pipes won't get descriptors + 0 and 1 because that will screw up dup2 below. */ + pipe(reserved); + + /* Create a socket pair for communicating with ssh. */ + if (pipe(pin) < 0) + fatal("pipe: %s", strerror(errno)); + if (pipe(pout) < 0) + fatal("pipe: %s", strerror(errno)); + + /* Free the reserved descriptors. */ + close(reserved[0]); + close(reserved[1]); + + /* For a child to execute the command on the remote host using ssh. */ + if (fork() == 0) + { + char *args[100]; + unsigned int i; + + /* Child. */ + close(pin[1]); + close(pout[0]); + dup2(pin[0], 0); + dup2(pout[1], 1); + close(pin[0]); + close(pout[1]); + + i = 0; + args[i++] = SSH_PROGRAM; + args[i++] = "-x"; + args[i++] = "-oFallBackToRsh no"; + if (verbose) + args[i++] = "-v"; + if (compress) + args[i++] = "-C"; + if (batchmode) + args[i++] = "-oBatchMode yes"; + if (cipher != NULL) + { + args[i++] = "-c"; + args[i++] = cipher; + } + if (identity != NULL) + { + args[i++] = "-i"; + args[i++] = identity; + } + if (port != NULL) + { + args[i++] = "-p"; + args[i++] = port; + } + if (remuser != NULL) + { + args[i++] = "-l"; + args[i++] = remuser; + } + args[i++] = host; + args[i++] = cmd; + args[i++] = NULL; + + execvp(SSH_PROGRAM, args); + perror(SSH_PROGRAM); + exit(1); + } + /* Parent. Close the other side, and return the local side. */ + close(pin[0]); + *fdout = pin[1]; + close(pout[1]); + *fdin = pout[0]; + return 0; +} + +void fatal(const char *fmt, ...) +{ + va_list ap; + char buf[1024]; + + va_start(ap, fmt); + vsnprintf(buf, sizeof(buf), fmt, ap); + va_end(ap); + fprintf(stderr, "%s\n", buf); + exit(255); +} + +/* This stuff used to be in BSD rcp extern.h. */ + +typedef struct { + int cnt; + char *buf; +} BUF; + +extern int iamremote; + +BUF *allocbuf(BUF *, int, int); +char *colon(char *); +void lostconn(int); +void nospace(void); +int okname(char *); +void run_err(const char *, ...); +void verifydir(char *); + +/* Stuff from BSD rcp.c continues. */ + +struct passwd *pwd; +uid_t userid; +int errs, remin, remout; +int pflag, iamremote, iamrecursive, targetshouldbedirectory; + +#define CMDNEEDS 64 +char cmd[CMDNEEDS]; /* must hold "rcp -r -p -d\0" */ + +int response(void); +void rsource(char *, struct stat *); +void sink(int, char *[]); +void source(int, char *[]); +void tolocal(int, char *[]); +void toremote(char *, int, char *[]); +void usage(void); + +int +main(argc, argv) + int argc; + char *argv[]; +{ + int ch, fflag, tflag; + char *targ; + extern char *optarg; + extern int optind; + + fflag = tflag = 0; + while ((ch = getopt(argc, argv, "dfprtvBCc:i:P:q")) != EOF) + switch(ch) { /* User-visible flags. */ + case 'p': + pflag = 1; + break; + case 'P': + port = optarg; + break; + case 'r': + iamrecursive = 1; + break; + /* Server options. */ + case 'd': + targetshouldbedirectory = 1; + break; + case 'f': /* "from" */ + iamremote = 1; + fflag = 1; + break; + case 't': /* "to" */ + iamremote = 1; + tflag = 1; + break; + case 'c': + cipher = optarg; + break; + case 'i': + identity = optarg; + break; + case 'v': + verbose = 1; + break; + case 'B': + batchmode = 1; + break; + case 'C': + compress = 1; + break; + case 'q': + showprogress = 0; + break; + case '?': + default: + usage(); + } + argc -= optind; + argv += optind; + + if ((pwd = getpwuid(userid = getuid())) == NULL) + fatal("unknown user %d", (int)userid); + + if (! isatty(STDERR_FILENO)) + showprogress = 0; + + remin = STDIN_FILENO; + remout = STDOUT_FILENO; + + if (fflag) { /* Follow "protocol", send data. */ + (void)response(); + source(argc, argv); + exit(errs != 0); + } + + if (tflag) { /* Receive data. */ + sink(argc, argv); + exit(errs != 0); + } + + if (argc < 2) + usage(); + if (argc > 2) + targetshouldbedirectory = 1; + + remin = remout = -1; + /* Command to be executed on remote system using "ssh". */ + (void)sprintf(cmd, "scp%s%s%s%s", verbose ? " -v" : "", + iamrecursive ? " -r" : "", pflag ? " -p" : "", + targetshouldbedirectory ? " -d" : ""); + + (void)signal(SIGPIPE, lostconn); + + if ((targ = colon(argv[argc - 1]))) /* Dest is remote host. */ + toremote(targ, argc, argv); + else { + tolocal(argc, argv); /* Dest is local host. */ + if (targetshouldbedirectory) + verifydir(argv[argc - 1]); + } + exit(errs != 0); +} + +void +toremote(targ, argc, argv) + char *targ, *argv[]; + int argc; +{ + int i, len; + char *bp, *host, *src, *suser, *thost, *tuser; + + *targ++ = 0; + if (*targ == 0) + targ = "."; + + if ((thost = strchr(argv[argc - 1], '@'))) { + /* user@host */ + *thost++ = 0; + tuser = argv[argc - 1]; + if (*tuser == '\0') + tuser = NULL; + else if (!okname(tuser)) + exit(1); + } else { + thost = argv[argc - 1]; + tuser = NULL; + } + + for (i = 0; i < argc - 1; i++) { + src = colon(argv[i]); + if (src) { /* remote to remote */ + *src++ = 0; + if (*src == 0) + src = "."; + host = strchr(argv[i], '@'); + len = strlen(SSH_PROGRAM) + strlen(argv[i]) + + strlen(src) + (tuser ? strlen(tuser) : 0) + + strlen(thost) + strlen(targ) + CMDNEEDS + 32; + bp = xmalloc(len); + if (host) { + *host++ = 0; + suser = argv[i]; + if (*suser == '\0') + suser = pwd->pw_name; + else if (!okname(suser)) + continue; + (void)sprintf(bp, + "%s%s -x -o'FallBackToRsh no' -n -l %s %s %s %s '%s%s%s:%s'", + SSH_PROGRAM, verbose ? " -v" : "", + suser, host, cmd, src, + tuser ? tuser : "", tuser ? "@" : "", + thost, targ); + } else + (void)sprintf(bp, + "exec %s%s -x -o'FallBackToRsh no' -n %s %s %s '%s%s%s:%s'", + SSH_PROGRAM, verbose ? " -v" : "", + argv[i], cmd, src, + tuser ? tuser : "", tuser ? "@" : "", + thost, targ); + if (verbose) + fprintf(stderr, "Executing: %s\n", bp); + (void)system(bp); + (void)xfree(bp); + } else { /* local to remote */ + if (remin == -1) { + len = strlen(targ) + CMDNEEDS + 20; + bp = xmalloc(len); + (void)sprintf(bp, "%s -t %s", cmd, targ); + host = thost; + if (do_cmd(host, tuser, + bp, &remin, &remout) < 0) + exit(1); + if (response() < 0) + exit(1); + (void)xfree(bp); + } + source(1, argv+i); + } + } +} + +void +tolocal(argc, argv) + int argc; + char *argv[]; +{ + int i, len; + char *bp, *host, *src, *suser; + + for (i = 0; i < argc - 1; i++) { + if (!(src = colon(argv[i]))) { /* Local to local. */ + len = strlen(_PATH_CP) + strlen(argv[i]) + + strlen(argv[argc - 1]) + 20; + bp = xmalloc(len); + (void)sprintf(bp, "exec %s%s%s %s %s", _PATH_CP, + iamrecursive ? " -r" : "", pflag ? " -p" : "", + argv[i], argv[argc - 1]); + if (verbose) + fprintf(stderr, "Executing: %s\n", bp); + if (system(bp)) + ++errs; + (void)xfree(bp); + continue; + } + *src++ = 0; + if (*src == 0) + src = "."; + if ((host = strchr(argv[i], '@')) == NULL) { + host = argv[i]; + suser = NULL; + } else { + *host++ = 0; + suser = argv[i]; + if (*suser == '\0') + suser = pwd->pw_name; + else if (!okname(suser)) + continue; + } + len = strlen(src) + CMDNEEDS + 20; + bp = xmalloc(len); + (void)sprintf(bp, "%s -f %s", cmd, src); + if (do_cmd(host, suser, bp, &remin, &remout) < 0) { + (void)xfree(bp); + ++errs; + continue; + } + xfree(bp); + sink(1, argv + argc - 1); + (void)close(remin); + remin = remout = -1; + } +} + +void +source(argc, argv) + int argc; + char *argv[]; +{ + struct stat stb; + static BUF buffer; + BUF *bp; + off_t i; + int amt, fd, haderr, indx, result; + char *last, *name, buf[2048]; + + for (indx = 0; indx < argc; ++indx) { + name = argv[indx]; + statbytes = 0; + if ((fd = open(name, O_RDONLY, 0)) < 0) + goto syserr; + if (fstat(fd, &stb) < 0) { +syserr: run_err("%s: %s", name, strerror(errno)); + goto next; + } + switch (stb.st_mode & S_IFMT) { + case S_IFREG: + break; + case S_IFDIR: + if (iamrecursive) { + rsource(name, &stb); + goto next; + } + /* FALLTHROUGH */ + default: + run_err("%s: not a regular file", name); + goto next; + } + if ((last = strrchr(name, '/')) == NULL) + last = name; + else + ++last; + curfile = last; + if (pflag) { + /* + * Make it compatible with possible future + * versions expecting microseconds. + */ + (void)sprintf(buf, "T%lu 0 %lu 0\n", + (unsigned long)stb.st_mtime, + (unsigned long)stb.st_atime); + (void)write(remout, buf, strlen(buf)); + if (response() < 0) + goto next; + } +#define FILEMODEMASK (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) + (void)sprintf(buf, "C%04o %lu %s\n", + (unsigned int)(stb.st_mode & FILEMODEMASK), + (unsigned long)stb.st_size, + last); + if (verbose) + { + fprintf(stderr, "Sending file modes: %s", buf); + fflush(stderr); + } + (void)write(remout, buf, strlen(buf)); + if (response() < 0) + goto next; + if ((bp = allocbuf(&buffer, fd, 2048)) == NULL) { +next: (void)close(fd); + continue; + } + + if (showprogress) { + totalbytes = stb.st_size; + progressmeter(-1); + } + + /* Keep writing after an error so that we stay sync'd up. */ + for (haderr = i = 0; i < stb.st_size; i += bp->cnt) { + amt = bp->cnt; + if (i + amt > stb.st_size) + amt = stb.st_size - i; + if (!haderr) { + result = read(fd, bp->buf, amt); + if (result != amt) + haderr = result >= 0 ? EIO : errno; + } + if (haderr) + (void)write(remout, bp->buf, amt); + else { + result = write(remout, bp->buf, amt); + if (result != amt) + haderr = result >= 0 ? EIO : errno; + statbytes += result; + } + } + if(showprogress) + progressmeter(1); + + if (close(fd) < 0 && !haderr) + haderr = errno; + if (!haderr) + (void)write(remout, "", 1); + else + run_err("%s: %s", name, strerror(haderr)); + (void)response(); + } +} + +void +rsource(name, statp) + char *name; + struct stat *statp; +{ + DIR *dirp; + struct dirent *dp; + char *last, *vect[1], path[1100]; + + if (!(dirp = opendir(name))) { + run_err("%s: %s", name, strerror(errno)); + return; + } + last = strrchr(name, '/'); + if (last == 0) + last = name; + else + last++; + if (pflag) { + (void)sprintf(path, "T%lu 0 %lu 0\n", + (unsigned long)statp->st_mtime, + (unsigned long)statp->st_atime); + (void)write(remout, path, strlen(path)); + if (response() < 0) { + closedir(dirp); + return; + } + } + (void)sprintf(path, + "D%04o %d %.1024s\n", (unsigned int)(statp->st_mode & FILEMODEMASK), + 0, last); + if (verbose) + fprintf(stderr, "Entering directory: %s", path); + (void)write(remout, path, strlen(path)); + if (response() < 0) { + closedir(dirp); + return; + } + while ((dp = readdir(dirp))) { + if (dp->d_ino == 0) + continue; + if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, "..")) + continue; + if (strlen(name) + 1 + strlen(dp->d_name) >= sizeof(path) - 1) { + run_err("%s/%s: name too long", name, dp->d_name); + continue; + } + (void)sprintf(path, "%s/%s", name, dp->d_name); + vect[0] = path; + source(1, vect); + } + (void)closedir(dirp); + (void)write(remout, "E\n", 2); + (void)response(); +} + +void +sink(argc, argv) + int argc; + char *argv[]; +{ + static BUF buffer; + struct stat stb; + enum { YES, NO, DISPLAYED } wrerr; + BUF *bp; + off_t i, j; + int amt, count, exists, first, mask, mode, ofd, omode; + int setimes, size, targisdir, wrerrno = 0; + char ch, *cp, *np, *targ, *why, *vect[1], buf[2048]; + struct utimbuf ut; + int dummy_usec; + +#define SCREWUP(str) { why = str; goto screwup; } + + setimes = targisdir = 0; + mask = umask(0); + if (!pflag) + (void)umask(mask); + if (argc != 1) { + run_err("ambiguous target"); + exit(1); + } + targ = *argv; + if (targetshouldbedirectory) + verifydir(targ); + + (void)write(remout, "", 1); + if (stat(targ, &stb) == 0 && S_ISDIR(stb.st_mode)) + targisdir = 1; + for (first = 1;; first = 0) { + cp = buf; + if (read(remin, cp, 1) <= 0) + return; + if (*cp++ == '\n') + SCREWUP("unexpected "); + do { + if (read(remin, &ch, sizeof(ch)) != sizeof(ch)) + SCREWUP("lost connection"); + *cp++ = ch; + } while (cp < &buf[sizeof(buf) - 1] && ch != '\n'); + *cp = 0; + + if (buf[0] == '\01' || buf[0] == '\02') { + if (iamremote == 0) + (void)write(STDERR_FILENO, + buf + 1, strlen(buf + 1)); + if (buf[0] == '\02') + exit(1); + ++errs; + continue; + } + if (buf[0] == 'E') { + (void)write(remout, "", 1); + return; + } + + if (ch == '\n') + *--cp = 0; + +#define getnum(t) (t) = 0; \ + while (*cp >= '0' && *cp <= '9') (t) = (t) * 10 + (*cp++ - '0'); + cp = buf; + if (*cp == 'T') { + setimes++; + cp++; + getnum(ut.modtime); + if (*cp++ != ' ') + SCREWUP("mtime.sec not delimited"); + getnum(dummy_usec); + if (*cp++ != ' ') + SCREWUP("mtime.usec not delimited"); + getnum(ut.actime); + if (*cp++ != ' ') + SCREWUP("atime.sec not delimited"); + getnum(dummy_usec); + if (*cp++ != '\0') + SCREWUP("atime.usec not delimited"); + (void)write(remout, "", 1); + continue; + } + if (*cp != 'C' && *cp != 'D') { + /* + * Check for the case "rcp remote:foo\* local:bar". + * In this case, the line "No match." can be returned + * by the shell before the rcp command on the remote is + * executed so the ^Aerror_message convention isn't + * followed. + */ + if (first) { + run_err("%s", cp); + exit(1); + } + SCREWUP("expected control record"); + } + mode = 0; + for (++cp; cp < buf + 5; cp++) { + if (*cp < '0' || *cp > '7') + SCREWUP("bad mode"); + mode = (mode << 3) | (*cp - '0'); + } + if (*cp++ != ' ') + SCREWUP("mode not delimited"); + + for (size = 0; *cp >= '0' && *cp <= '9';) + size = size * 10 + (*cp++ - '0'); + if (*cp++ != ' ') + SCREWUP("size not delimited"); + if (targisdir) { + static char *namebuf; + static int cursize; + size_t need; + + need = strlen(targ) + strlen(cp) + 250; + if (need > cursize) + namebuf = xmalloc(need); + (void)sprintf(namebuf, "%s%s%s", targ, + *targ ? "/" : "", cp); + np = namebuf; + } else + np = targ; + curfile = cp; + exists = stat(np, &stb) == 0; + if (buf[0] == 'D') { + int mod_flag = pflag; + if (exists) { + if (!S_ISDIR(stb.st_mode)) { + errno = ENOTDIR; + goto bad; + } + if (pflag) + (void)chmod(np, mode); + } else { + /* Handle copying from a read-only directory */ + mod_flag = 1; + if (mkdir(np, mode | S_IRWXU) < 0) + goto bad; + } + vect[0] = np; + sink(1, vect); + if (setimes) { + setimes = 0; + if (utime(np, &ut) < 0) + run_err("%s: set times: %s", + np, strerror(errno)); + } + if (mod_flag) + (void)chmod(np, mode); + continue; + } + omode = mode; + mode |= S_IWRITE; + if ((ofd = open(np, O_WRONLY|O_CREAT|O_TRUNC, mode)) < 0) { +bad: run_err("%s: %s", np, strerror(errno)); + continue; + } + (void)write(remout, "", 1); + if ((bp = allocbuf(&buffer, ofd, 4096)) == NULL) { + (void)close(ofd); + continue; + } + cp = bp->buf; + wrerr = NO; + + if (showprogress) { + totalbytes = size; + progressmeter(-1); + } + statbytes = 0; + for (count = i = 0; i < size; i += 4096) { + amt = 4096; + if (i + amt > size) + amt = size - i; + count += amt; + do { + j = read(remin, cp, amt); + if (j <= 0) { + run_err("%s", j ? strerror(errno) : + "dropped connection"); + exit(1); + } + amt -= j; + cp += j; + statbytes += j; + } while (amt > 0); + if (count == bp->cnt) { + /* Keep reading so we stay sync'd up. */ + if (wrerr == NO) { + j = write(ofd, bp->buf, count); + if (j != count) { + wrerr = YES; + wrerrno = j >= 0 ? EIO : errno; + } + } + count = 0; + cp = bp->buf; + } + } + if (showprogress) + progressmeter(1); + if (count != 0 && wrerr == NO && + (j = write(ofd, bp->buf, count)) != count) { + wrerr = YES; + wrerrno = j >= 0 ? EIO : errno; + } +#if 0 + if (ftruncate(ofd, size)) { + run_err("%s: truncate: %s", np, strerror(errno)); + wrerr = DISPLAYED; + } +#endif + if (pflag) { + if (exists || omode != mode) + if (fchmod(ofd, omode)) + run_err("%s: set mode: %s", + np, strerror(errno)); + } else { + if (!exists && omode != mode) + if (fchmod(ofd, omode & ~mask)) + run_err("%s: set mode: %s", + np, strerror(errno)); + } + (void)close(ofd); + (void)response(); + if (setimes && wrerr == NO) { + setimes = 0; + if (utime(np, &ut) < 0) { + run_err("%s: set times: %s", + np, strerror(errno)); + wrerr = DISPLAYED; + } + } + switch(wrerr) { + case YES: + run_err("%s: %s", np, strerror(wrerrno)); + break; + case NO: + (void)write(remout, "", 1); + break; + case DISPLAYED: + break; + } + } +screwup: + run_err("protocol error: %s", why); + exit(1); +} + +int +response() +{ + char ch, *cp, resp, rbuf[2048]; + + if (read(remin, &resp, sizeof(resp)) != sizeof(resp)) + lostconn(0); + + cp = rbuf; + switch(resp) { + case 0: /* ok */ + return (0); + default: + *cp++ = resp; + /* FALLTHROUGH */ + case 1: /* error, followed by error msg */ + case 2: /* fatal error, "" */ + do { + if (read(remin, &ch, sizeof(ch)) != sizeof(ch)) + lostconn(0); + *cp++ = ch; + } while (cp < &rbuf[sizeof(rbuf) - 1] && ch != '\n'); + + if (!iamremote) + (void)write(STDERR_FILENO, rbuf, cp - rbuf); + ++errs; + if (resp == 1) + return (-1); + exit(1); + } + /* NOTREACHED */ +} + +void +usage() +{ + (void)fprintf(stderr, + "usage: scp [-pqrvC] [-P port] [-c cipher] [-i identity] f1 f2; or:\n scp [options] f1 ... fn directory\n"); + exit(1); +} + +void +run_err(const char *fmt, ...) +{ + static FILE *fp; + va_list ap; + va_start(ap, fmt); + + ++errs; + if (fp == NULL && !(fp = fdopen(remout, "w"))) + return; + (void)fprintf(fp, "%c", 0x01); + (void)fprintf(fp, "scp: "); + (void)vfprintf(fp, fmt, ap); + (void)fprintf(fp, "\n"); + (void)fflush(fp); + + if (!iamremote) + { + vfprintf(stderr, fmt, ap); + fprintf(stderr, "\n"); + } + + va_end(ap); +} + +/* Stuff below is from BSD rcp util.c. */ + +/*- + * Copyright (c) 1992, 1993 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $Id$ + */ + +char * +colon(cp) + char *cp; +{ + if (*cp == ':') /* Leading colon is part of file name. */ + return (0); + + for (; *cp; ++cp) { + if (*cp == ':') + return (cp); + if (*cp == '/') + return (0); + } + return (0); +} + +void +verifydir(cp) + char *cp; +{ + struct stat stb; + + if (!stat(cp, &stb)) { + if (S_ISDIR(stb.st_mode)) + return; + errno = ENOTDIR; + } + run_err("%s: %s", cp, strerror(errno)); + exit(1); +} + +int +okname(cp0) + char *cp0; +{ + int c; + char *cp; + + cp = cp0; + do { + c = *cp; + if (c & 0200) + goto bad; + if (!isalpha(c) && !isdigit(c) && c != '_' && c != '-') + goto bad; + } while (*++cp); + return (1); + +bad: fprintf(stderr, "%s: invalid user name", cp0); + return (0); +} + +BUF * +allocbuf(bp, fd, blksize) + BUF *bp; + int fd, blksize; +{ + size_t size; + struct stat stb; + + if (fstat(fd, &stb) < 0) { + run_err("fstat: %s", strerror(errno)); + return (0); + } + if (stb.st_blksize == 0) + size = blksize; + else + size = blksize + (stb.st_blksize - blksize % stb.st_blksize) % + stb.st_blksize; + if (bp->cnt >= size) + return (bp); + if (bp->buf == NULL) + bp->buf = xmalloc(size); + else + bp->buf = xrealloc(bp->buf, size); + bp->cnt = size; + return (bp); +} + +void +lostconn(signo) + int signo; +{ + if (!iamremote) + fprintf(stderr, "lost connection\n"); + exit(1); +} + +/* + * ensure all of data on socket comes through. f==read || f==write + */ +int +atomicio(f, fd, s, n) +int (*f)(); +char *s; +{ + int res, pos = 0; + + while (n>pos) { + res = (f)(fd, s+pos, n-pos); + switch (res) { + case -1: + if (errno==EINTR || errno==EAGAIN) + continue; + case 0: + return (res); + default: + pos += res; + } + } + return (pos); +} + +void +alarmtimer(int wait) +{ + struct itimerval itv; + + itv.it_value.tv_sec = wait; + itv.it_value.tv_usec = 0; + itv.it_interval = itv.it_value; + setitimer(ITIMER_REAL, &itv, NULL); +} + +void +updateprogressmeter(void) +{ + int save_errno = errno; + + progressmeter(0); + errno = save_errno; +} + +void +progressmeter(int flag) +{ + static const char prefixes[] = " KMGTP"; + static struct timeval lastupdate; + static off_t lastsize; + struct timeval now, td, wait; + off_t cursize, abbrevsize; + double elapsed; + int ratio, barlength, i, remaining; + char buf[256]; + + if (flag == -1) { + (void)gettimeofday(&start, (struct timezone *)0); + lastupdate = start; + lastsize = 0; + } + (void)gettimeofday(&now, (struct timezone *)0); + cursize = statbytes; + if (totalbytes != 0) { + ratio = cursize * 100 / totalbytes; + ratio = MAX(ratio, 0); + ratio = MIN(ratio, 100); + } + else + ratio = 100; + + snprintf(buf, sizeof(buf), "\r%-20.20s %3d%% ", curfile, ratio); + + barlength = getttywidth() - 51; + if (barlength > 0) { + i = barlength * ratio / 100; + snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), + "|%.*s%*s|", i, +"*****************************************************************************" +"*****************************************************************************", + barlength - i, ""); + } + + i = 0; + abbrevsize = cursize; + while (abbrevsize >= 100000 && i < sizeof(prefixes)) { + i++; + abbrevsize >>= 10; + } + snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), " %5qd %c%c ", + (quad_t)abbrevsize, prefixes[i], prefixes[i] == ' ' ? ' ' : + 'B'); + + timersub(&now, &lastupdate, &wait); + if (cursize > lastsize) { + lastupdate = now; + lastsize = cursize; + if (wait.tv_sec >= STALLTIME) { + start.tv_sec += wait.tv_sec; + start.tv_usec += wait.tv_usec; + } + wait.tv_sec = 0; + } + + timersub(&now, &start, &td); + elapsed = td.tv_sec + (td.tv_usec / 1000000.0); + + if (statbytes <= 0 || elapsed <= 0.0 || cursize > totalbytes) { + snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), + " --:-- ETA"); + } else if (wait.tv_sec >= STALLTIME) { + snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), + " - stalled -"); + } else { + remaining = (int)(totalbytes / (statbytes / elapsed) - elapsed); + i = elapsed / 3600; + if (i) + snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), + "%2d:", i); + else + snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), + " "); + i = remaining % 3600; + snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), + "%02d:%02d ETA", i / 60, i % 60); + } + atomicio(write, fileno(stdout), buf, strlen(buf)); + + if (flag == -1) { + signal(SIGALRM, (void *)updateprogressmeter); + alarmtimer(1); + } else if (flag == 1) { + alarmtimer(0); + write(fileno(stdout), "\n", 1); + statbytes = 0; + } +} + +int +getttywidth(void) +{ + struct winsize winsize; + + if (ioctl(fileno(stdout), TIOCGWINSZ, &winsize) != -1) + return(winsize.ws_col ? winsize.ws_col : 80); + else + return(80); +} + + diff --git a/servconf.c b/servconf.c new file mode 100644 index 00000000..8c95a9af --- /dev/null +++ b/servconf.c @@ -0,0 +1,567 @@ +/* + +servconf.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Mon Aug 21 15:48:58 1995 ylo + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include "servconf.h" +#include "xmalloc.h" + +/* Initializes the server options to their default values. */ + +void initialize_server_options(ServerOptions *options) +{ + memset(options, 0, sizeof(*options)); + options->port = -1; + options->listen_addr.s_addr = htonl(INADDR_ANY); + options->host_key_file = NULL; + options->server_key_bits = -1; + options->login_grace_time = -1; + options->key_regeneration_time = -1; + options->permit_root_login = -1; + options->ignore_rhosts = -1; + options->quiet_mode = -1; + options->fascist_logging = -1; + options->print_motd = -1; + options->check_mail = -1; + options->x11_forwarding = -1; + options->x11_display_offset = -1; + options->strict_modes = -1; + options->keepalives = -1; + options->log_facility = (SyslogFacility)-1; + options->rhosts_authentication = -1; + options->rhosts_rsa_authentication = -1; + options->rsa_authentication = -1; +#ifdef KRB4 + options->kerberos_authentication = -1; + options->kerberos_or_local_passwd = -1; + options->kerberos_ticket_cleanup = -1; +#endif +#ifdef AFS + options->kerberos_tgt_passing = -1; + options->afs_token_passing = -1; +#endif + options->password_authentication = -1; +#ifdef SKEY + options->skey_authentication = -1; +#endif + options->permit_empty_passwd = -1; + options->use_login = -1; + options->num_allow_users = 0; + options->num_deny_users = 0; + options->num_allow_groups = 0; + options->num_deny_groups = 0; +} + +void fill_default_server_options(ServerOptions *options) +{ + if (options->port == -1) + { + struct servent *sp; + + sp = getservbyname(SSH_SERVICE_NAME, "tcp"); + if (sp) + options->port = ntohs(sp->s_port); + else + options->port = SSH_DEFAULT_PORT; + endservent(); + } + if (options->host_key_file == NULL) + options->host_key_file = HOST_KEY_FILE; + if (options->server_key_bits == -1) + options->server_key_bits = 768; + if (options->login_grace_time == -1) + options->login_grace_time = 600; + if (options->key_regeneration_time == -1) + options->key_regeneration_time = 3600; + if (options->permit_root_login == -1) + options->permit_root_login = 1; /* yes */ + if (options->ignore_rhosts == -1) + options->ignore_rhosts = 0; + if (options->quiet_mode == -1) + options->quiet_mode = 0; + if (options->check_mail == -1) + options->check_mail = 0; + if (options->fascist_logging == -1) + options->fascist_logging = 1; + if (options->print_motd == -1) + options->print_motd = 1; + if (options->x11_forwarding == -1) + options->x11_forwarding = 1; + if (options->x11_display_offset == -1) + options->x11_display_offset = 1; + if (options->strict_modes == -1) + options->strict_modes = 1; + if (options->keepalives == -1) + options->keepalives = 1; + if (options->log_facility == (SyslogFacility)(-1)) + options->log_facility = SYSLOG_FACILITY_AUTH; + if (options->rhosts_authentication == -1) + options->rhosts_authentication = 0; + if (options->rhosts_rsa_authentication == -1) + options->rhosts_rsa_authentication = 1; + if (options->rsa_authentication == -1) + options->rsa_authentication = 1; +#ifdef KRB4 + if (options->kerberos_authentication == -1) + options->kerberos_authentication = (access(KEYFILE, R_OK) == 0); + if (options->kerberos_or_local_passwd == -1) + options->kerberos_or_local_passwd = 1; + if (options->kerberos_ticket_cleanup == -1) + options->kerberos_ticket_cleanup = 1; +#endif /* KRB4 */ +#ifdef AFS + if (options->kerberos_tgt_passing == -1) + options->kerberos_tgt_passing = 0; + if (options->afs_token_passing == -1) + options->afs_token_passing = k_hasafs(); +#endif /* AFS */ + if (options->password_authentication == -1) + options->password_authentication = 1; +#ifdef SKEY + if (options->skey_authentication == -1) + options->skey_authentication = 1; +#endif + if (options->permit_empty_passwd == -1) + options->permit_empty_passwd = 1; + if (options->use_login == -1) + options->use_login = 0; +} + +#define WHITESPACE " \t\r\n" + +/* Keyword tokens. */ +typedef enum +{ + sPort, sHostKeyFile, sServerKeyBits, sLoginGraceTime, sKeyRegenerationTime, + sPermitRootLogin, sQuietMode, sFascistLogging, sLogFacility, + sRhostsAuthentication, sRhostsRSAAuthentication, sRSAAuthentication, +#ifdef KRB4 + sKerberosAuthentication, sKerberosOrLocalPasswd, sKerberosTicketCleanup, +#endif +#ifdef AFS + sKerberosTgtPassing, sAFSTokenPassing, +#endif +#ifdef SKEY + sSkeyAuthentication, +#endif + sPasswordAuthentication, sListenAddress, + sPrintMotd, sIgnoreRhosts, sX11Forwarding, sX11DisplayOffset, + sStrictModes, sEmptyPasswd, sRandomSeedFile, sKeepAlives, sCheckMail, + sUseLogin, sAllowUsers, sDenyUsers, sAllowGroups, sDenyGroups + +} ServerOpCodes; + +/* Textual representation of the tokens. */ +static struct +{ + const char *name; + ServerOpCodes opcode; +} keywords[] = +{ + { "port", sPort }, + { "hostkey", sHostKeyFile }, + { "serverkeybits", sServerKeyBits }, + { "logingracetime", sLoginGraceTime }, + { "keyregenerationinterval", sKeyRegenerationTime }, + { "permitrootlogin", sPermitRootLogin }, + { "quietmode", sQuietMode }, + { "fascistlogging", sFascistLogging }, + { "syslogfacility", sLogFacility }, + { "rhostsauthentication", sRhostsAuthentication }, + { "rhostsrsaauthentication", sRhostsRSAAuthentication }, + { "rsaauthentication", sRSAAuthentication }, +#ifdef KRB4 + { "kerberosauthentication", sKerberosAuthentication }, + { "kerberosorlocalpasswd", sKerberosOrLocalPasswd }, + { "kerberosticketcleanup", sKerberosTicketCleanup }, +#endif +#ifdef AFS + { "kerberostgtpassing", sKerberosTgtPassing }, + { "afstokenpassing", sAFSTokenPassing }, +#endif + { "passwordauthentication", sPasswordAuthentication }, +#ifdef SKEY + { "skeyauthentication", sSkeyAuthentication }, +#endif + { "checkmail", sCheckMail }, + { "listenaddress", sListenAddress }, + { "printmotd", sPrintMotd }, + { "ignorerhosts", sIgnoreRhosts }, + { "x11forwarding", sX11Forwarding }, + { "x11displayoffset", sX11DisplayOffset }, + { "strictmodes", sStrictModes }, + { "permitemptypasswords", sEmptyPasswd }, + { "uselogin", sUseLogin }, + { "randomseed", sRandomSeedFile }, + { "keepalive", sKeepAlives }, + { "allowusers", sAllowUsers }, + { "denyusers", sDenyUsers }, + { "allowgroups", sAllowGroups }, + { "denygroups", sDenyGroups }, + { NULL, 0 } +}; + +static struct +{ + const char *name; + SyslogFacility facility; +} log_facilities[] = +{ + { "DAEMON", SYSLOG_FACILITY_DAEMON }, + { "USER", SYSLOG_FACILITY_USER }, + { "AUTH", SYSLOG_FACILITY_AUTH }, + { "LOCAL0", SYSLOG_FACILITY_LOCAL0 }, + { "LOCAL1", SYSLOG_FACILITY_LOCAL1 }, + { "LOCAL2", SYSLOG_FACILITY_LOCAL2 }, + { "LOCAL3", SYSLOG_FACILITY_LOCAL3 }, + { "LOCAL4", SYSLOG_FACILITY_LOCAL4 }, + { "LOCAL5", SYSLOG_FACILITY_LOCAL5 }, + { "LOCAL6", SYSLOG_FACILITY_LOCAL6 }, + { "LOCAL7", SYSLOG_FACILITY_LOCAL7 }, + { NULL, 0 } +}; + +/* Returns the number of the token pointed to by cp of length len. + Never returns if the token is not known. */ + +static ServerOpCodes parse_token(const char *cp, const char *filename, + int linenum) +{ + unsigned int i; + + for (i = 0; keywords[i].name; i++) + if (strcmp(cp, keywords[i].name) == 0) + return keywords[i].opcode; + + fprintf(stderr, "%s line %d: Bad configuration option: %s\n", + filename, linenum, cp); + exit(1); +} + +/* Reads the server configuration file. */ + +void read_server_config(ServerOptions *options, const char *filename) +{ + FILE *f; + char line[1024]; + char *cp, **charptr; + int linenum, *intptr, i, value; + ServerOpCodes opcode; + + f = fopen(filename, "r"); + if (!f) + { + perror(filename); + exit(1); + } + + linenum = 0; + while (fgets(line, sizeof(line), f)) + { + linenum++; + cp = line + strspn(line, WHITESPACE); + if (!*cp || *cp == '#') + continue; + cp = strtok(cp, WHITESPACE); + { + char *t = cp; + for (; *t != 0; t++) + if ('A' <= *t && *t <= 'Z') + *t = *t - 'A' + 'a'; /* tolower */ + + } + opcode = parse_token(cp, filename, linenum); + switch (opcode) + { + case sPort: + intptr = &options->port; + parse_int: + cp = strtok(NULL, WHITESPACE); + if (!cp) + { + fprintf(stderr, "%s line %d: missing integer value.\n", + filename, linenum); + exit(1); + } + value = atoi(cp); + if (*intptr == -1) + *intptr = value; + break; + + case sServerKeyBits: + intptr = &options->server_key_bits; + goto parse_int; + + case sLoginGraceTime: + intptr = &options->login_grace_time; + goto parse_int; + + case sKeyRegenerationTime: + intptr = &options->key_regeneration_time; + goto parse_int; + + case sListenAddress: + cp = strtok(NULL, WHITESPACE); + if (!cp) + { + fprintf(stderr, "%s line %d: missing inet addr.\n", + filename, linenum); + exit(1); + } + options->listen_addr.s_addr = inet_addr(cp); + break; + + case sHostKeyFile: + charptr = &options->host_key_file; + cp = strtok(NULL, WHITESPACE); + if (!cp) + { + fprintf(stderr, "%s line %d: missing file name.\n", + filename, linenum); + exit(1); + } + if (*charptr == NULL) + *charptr = tilde_expand_filename(cp, getuid()); + break; + + case sRandomSeedFile: + fprintf(stderr, "%s line %d: \"randomseed\" option is obsolete.\n", + filename, linenum); + cp = strtok(NULL, WHITESPACE); + break; + + case sPermitRootLogin: + intptr = &options->permit_root_login; + cp = strtok(NULL, WHITESPACE); + if (!cp) + { + fprintf(stderr, "%s line %d: missing yes/without-password/no argument.\n", + filename, linenum); + exit(1); + } + if (strcmp(cp, "without-password") == 0) + value = 2; + else if (strcmp(cp, "yes") == 0) + value = 1; + else if (strcmp(cp, "no") == 0) + value = 0; + else + { + fprintf(stderr, "%s line %d: Bad yes/without-password/no argument: %s\n", + filename, linenum, cp); + exit(1); + } + if (*intptr == -1) + *intptr = value; + break; + + case sIgnoreRhosts: + intptr = &options->ignore_rhosts; + parse_flag: + cp = strtok(NULL, WHITESPACE); + if (!cp) + { + fprintf(stderr, "%s line %d: missing yes/no argument.\n", + filename, linenum); + exit(1); + } + if (strcmp(cp, "yes") == 0) + value = 1; + else + if (strcmp(cp, "no") == 0) + value = 0; + else + { + fprintf(stderr, "%s line %d: Bad yes/no argument: %s\n", + filename, linenum, cp); + exit(1); + } + if (*intptr == -1) + *intptr = value; + break; + + case sQuietMode: + intptr = &options->quiet_mode; + goto parse_flag; + + case sFascistLogging: + intptr = &options->fascist_logging; + goto parse_flag; + + case sRhostsAuthentication: + intptr = &options->rhosts_authentication; + goto parse_flag; + + case sRhostsRSAAuthentication: + intptr = &options->rhosts_rsa_authentication; + goto parse_flag; + + case sRSAAuthentication: + intptr = &options->rsa_authentication; + goto parse_flag; + +#ifdef KRB4 + case sKerberosAuthentication: + intptr = &options->kerberos_authentication; + goto parse_flag; + + case sKerberosOrLocalPasswd: + intptr = &options->kerberos_or_local_passwd; + goto parse_flag; + + case sKerberosTicketCleanup: + intptr = &options->kerberos_ticket_cleanup; + goto parse_flag; +#endif + +#ifdef AFS + case sKerberosTgtPassing: + intptr = &options->kerberos_tgt_passing; + goto parse_flag; + + case sAFSTokenPassing: + intptr = &options->afs_token_passing; + goto parse_flag; +#endif + + case sPasswordAuthentication: + intptr = &options->password_authentication; + goto parse_flag; + + case sCheckMail: + intptr = &options->check_mail; + goto parse_flag; + +#ifdef SKEY + case sSkeyAuthentication: + intptr = &options->skey_authentication; + goto parse_flag; +#endif + + case sPrintMotd: + intptr = &options->print_motd; + goto parse_flag; + + case sX11Forwarding: + intptr = &options->x11_forwarding; + goto parse_flag; + + case sX11DisplayOffset: + intptr = &options->x11_display_offset; + goto parse_int; + + case sStrictModes: + intptr = &options->strict_modes; + goto parse_flag; + + case sKeepAlives: + intptr = &options->keepalives; + goto parse_flag; + + case sEmptyPasswd: + intptr = &options->permit_empty_passwd; + goto parse_flag; + + case sUseLogin: + intptr = &options->use_login; + goto parse_flag; + + case sLogFacility: + cp = strtok(NULL, WHITESPACE); + if (!cp) + { + fprintf(stderr, "%s line %d: missing facility name.\n", + filename, linenum); + exit(1); + } + for (i = 0; log_facilities[i].name; i++) + if (strcmp(log_facilities[i].name, cp) == 0) + break; + if (!log_facilities[i].name) + { + fprintf(stderr, "%s line %d: unsupported log facility %s\n", + filename, linenum, cp); + exit(1); + } + if (options->log_facility == (SyslogFacility)(-1)) + options->log_facility = log_facilities[i].facility; + break; + + case sAllowUsers: + while ((cp = strtok(NULL, WHITESPACE))) + { + if (options->num_allow_users >= MAX_ALLOW_USERS) + { + fprintf(stderr, "%s line %d: too many allow users.\n", + filename, linenum); + exit(1); + } + options->allow_users[options->num_allow_users++] = xstrdup(cp); + } + break; + + case sDenyUsers: + while ((cp = strtok(NULL, WHITESPACE))) + { + if (options->num_deny_users >= MAX_DENY_USERS) + { + fprintf(stderr, "%s line %d: too many deny users.\n", + filename, linenum); + exit(1); + } + options->deny_users[options->num_deny_users++] = xstrdup(cp); + } + break; + + case sAllowGroups: + while ((cp = strtok(NULL, WHITESPACE))) + { + if (options->num_allow_groups >= MAX_ALLOW_GROUPS) + { + fprintf(stderr, "%s line %d: too many allow groups.\n", + filename, linenum); + exit(1); + } + options->allow_groups[options->num_allow_groups++] = xstrdup(cp); + } + break; + + case sDenyGroups: + while ((cp = strtok(NULL, WHITESPACE))) + { + if (options->num_deny_groups >= MAX_DENY_GROUPS) + { + fprintf(stderr, "%s line %d: too many deny groups.\n", + filename, linenum); + exit(1); + } + options->deny_groups[options->num_deny_groups++] = xstrdup(cp); + } + break; + + default: + fprintf(stderr, "%s line %d: Missing handler for opcode %s (%d)\n", + filename, linenum, cp, opcode); + exit(1); + } + if (strtok(NULL, WHITESPACE) != NULL) + { + fprintf(stderr, "%s line %d: garbage at end of line.\n", + filename, linenum); + exit(1); + } + } + fclose(f); +} diff --git a/servconf.h b/servconf.h new file mode 100644 index 00000000..8c630fce --- /dev/null +++ b/servconf.h @@ -0,0 +1,86 @@ +/* + +servconf.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Mon Aug 21 15:35:03 1995 ylo + +Definitions for server configuration data and for the functions reading it. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef SERVCONF_H +#define SERVCONF_H + +#define MAX_ALLOW_USERS 256 /* Max # users on allow list. */ +#define MAX_DENY_USERS 256 /* Max # users on deny list. */ +#define MAX_ALLOW_GROUPS 256 /* Max # groups on allow list. */ +#define MAX_DENY_GROUPS 256 /* Max # groups on deny list. */ + +typedef struct +{ + int port; /* Port number to listen on. */ + struct in_addr listen_addr; /* Address on which the server listens. */ + char *host_key_file; /* File containing host key. */ + int server_key_bits; /* Size of the server key. */ + int login_grace_time; /* Disconnect if no auth in this time (sec). */ + int key_regeneration_time; /* Server key lifetime (seconds). */ + int permit_root_login; /* If true, permit root login. */ + int ignore_rhosts; /* Ignore .rhosts and .shosts. */ + int quiet_mode; /* If true, don't log anything but fatals. */ + int fascist_logging; /* Perform very verbose logging. */ + int print_motd; /* If true, print /etc/motd. */ + int check_mail; /* If true, check for new mail. */ + int x11_forwarding; /* If true, permit inet (spoofing) X11 fwd. */ + int x11_display_offset; /* What DISPLAY number to start searching at */ + int strict_modes; /* If true, require string home dir modes. */ + int keepalives; /* If true, set SO_KEEPALIVE. */ + SyslogFacility log_facility; /* Facility for system logging. */ + int rhosts_authentication; /* If true, permit rhosts authentication. */ + int rhosts_rsa_authentication;/* If true, permit rhosts RSA authentication.*/ + int rsa_authentication; /* If true, permit RSA authentication. */ +#ifdef KRB4 + int kerberos_authentication; /* If true, permit Kerberos authentication. */ + int kerberos_or_local_passwd; /* If true, permit kerberos and any other + password authentication mechanism, such + as SecurID or /etc/passwd */ + int kerberos_ticket_cleanup; /* If true, destroy ticket file on logout. */ +#endif +#ifdef AFS + int kerberos_tgt_passing; /* If true, permit Kerberos tgt passing. */ + int afs_token_passing; /* If true, permit AFS token passing. */ +#endif + int password_authentication; /* If true, permit password authentication. */ +#ifdef SKEY + int skey_authentication; /* If true, permit s/key authentication. */ +#endif + int permit_empty_passwd; /* If false, do not permit empty passwords. */ + int use_login; /* If true, login(1) is used */ + unsigned int num_allow_users; + char *allow_users[MAX_ALLOW_USERS]; + unsigned int num_deny_users; + char *deny_users[MAX_DENY_USERS]; + unsigned int num_allow_groups; + char *allow_groups[MAX_ALLOW_GROUPS]; + unsigned int num_deny_groups; + char *deny_groups[MAX_DENY_GROUPS]; +} ServerOptions; + +/* Initializes the server options to special values that indicate that they + have not yet been set. */ +void initialize_server_options(ServerOptions *options); + +/* Reads the server configuration file. This only sets the values for those + options that have the special value indicating they have not been set. */ +void read_server_config(ServerOptions *options, const char *filename); + +/* Sets values for those values that have not yet been set. */ +void fill_default_server_options(ServerOptions *options); + +#endif /* SERVCONF_H */ diff --git a/serverloop.c b/serverloop.c new file mode 100644 index 00000000..552c69c2 --- /dev/null +++ b/serverloop.c @@ -0,0 +1,644 @@ +/* + +serverloop.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sun Sep 10 00:30:37 1995 ylo + +Server main loop for handling the interactive session. + +*/ + +#include "includes.h" +#include "xmalloc.h" +#include "ssh.h" +#include "packet.h" +#include "buffer.h" +#include "servconf.h" +#include "pty.h" + +static Buffer stdin_buffer; /* Buffer for stdin data. */ +static Buffer stdout_buffer; /* Buffer for stdout data. */ +static Buffer stderr_buffer; /* Buffer for stderr data. */ +static int fdin; /* Descriptor for stdin (for writing) */ +static int fdout; /* Descriptor for stdout (for reading); + May be same number as fdin. */ +static int fderr; /* Descriptor for stderr. May be -1. */ +static long stdin_bytes = 0; /* Number of bytes written to stdin. */ +static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ +static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ +static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ +static int stdin_eof = 0; /* EOF message received from client. */ +static int fdout_eof = 0; /* EOF encountered reading from fdout. */ +static int fderr_eof = 0; /* EOF encountered readung from fderr. */ +static int connection_in; /* Connection to client (input). */ +static int connection_out; /* Connection to client (output). */ +static unsigned int buffer_high;/* "Soft" max buffer size. */ +static int max_fd; /* Max file descriptor number for select(). */ + +/* This SIGCHLD kludge is used to detect when the child exits. The server + will exit after that, as soon as forwarded connections have terminated. */ + +static int child_pid; /* Pid of the child. */ +static volatile int child_terminated; /* The child has terminated. */ +static volatile int child_wait_status; /* Status from wait(). */ + +void sigchld_handler(int sig) +{ + int save_errno = errno; + int wait_pid; + debug("Received SIGCHLD."); + wait_pid = wait((int *)&child_wait_status); + if (wait_pid != -1) + { + if (wait_pid != child_pid) + error("Strange, got SIGCHLD and wait returned pid %d but child is %d", + wait_pid, child_pid); + if (WIFEXITED(child_wait_status) || + WIFSIGNALED(child_wait_status)) + child_terminated = 1; + } + signal(SIGCHLD, sigchld_handler); + errno = save_errno; +} + +/* Process any buffered packets that have been received from the client. */ + +void process_buffered_input_packets() +{ + int type; + char *data; + unsigned int data_len; + int row, col, xpixel, ypixel; + int payload_len; + + /* Process buffered packets from the client. */ + while ((type = packet_read_poll(&payload_len)) != SSH_MSG_NONE) + { + switch (type) + { + case SSH_CMSG_STDIN_DATA: + /* Stdin data from the client. Append it to the buffer. */ + if (fdin == -1) + break; /* Ignore any data if the client has closed stdin. */ + data = packet_get_string(&data_len); + packet_integrity_check(payload_len, (4 + data_len), type); + buffer_append(&stdin_buffer, data, data_len); + memset(data, 0, data_len); + xfree(data); + break; + + case SSH_CMSG_EOF: + /* Eof from the client. The stdin descriptor to the program + will be closed when all buffered data has drained. */ + debug("EOF received for stdin."); + packet_integrity_check(payload_len, 0, type); + stdin_eof = 1; + break; + + case SSH_CMSG_WINDOW_SIZE: + debug("Window change received."); + packet_integrity_check(payload_len, 4*4, type); + row = packet_get_int(); + col = packet_get_int(); + xpixel = packet_get_int(); + ypixel = packet_get_int(); + if (fdin != -1) + pty_change_window_size(fdin, row, col, xpixel, ypixel); + break; + + case SSH_MSG_PORT_OPEN: + debug("Received port open request."); + channel_input_port_open(payload_len); + break; + + case SSH_MSG_CHANNEL_OPEN_CONFIRMATION: + debug("Received channel open confirmation."); + packet_integrity_check(payload_len, 4 + 4, type); + channel_input_open_confirmation(); + break; + + case SSH_MSG_CHANNEL_OPEN_FAILURE: + debug("Received channel open failure."); + packet_integrity_check(payload_len, 4, type); + channel_input_open_failure(); + break; + + case SSH_MSG_CHANNEL_DATA: + channel_input_data(payload_len); + break; + + case SSH_MSG_CHANNEL_CLOSE: + debug("Received channel close."); + packet_integrity_check(payload_len, 4, type); + channel_input_close(); + break; + + case SSH_MSG_CHANNEL_CLOSE_CONFIRMATION: + debug("Received channel close confirmation."); + packet_integrity_check(payload_len, 4, type); + channel_input_close_confirmation(); + break; + + default: + /* In this phase, any unexpected messages cause a protocol + error. This is to ease debugging; also, since no + confirmations are sent messages, unprocessed unknown + messages could cause strange problems. Any compatible + protocol extensions must be negotiated before entering the + interactive session. */ + packet_disconnect("Protocol error during session: type %d", + type); + } + } +} + +/* Make packets from buffered stderr data, and buffer it for sending + to the client. */ + +void make_packets_from_stderr_data() +{ + int len; + + /* Send buffered stderr data to the client. */ + while (buffer_len(&stderr_buffer) > 0 && + packet_not_very_much_data_to_write()) + { + len = buffer_len(&stderr_buffer); + if (packet_is_interactive()) + { + if (len > 512) + len = 512; + } + else + { + if (len > 32768) + len = 32768; /* Keep the packets at reasonable size. */ + } + packet_start(SSH_SMSG_STDERR_DATA); + packet_put_string(buffer_ptr(&stderr_buffer), len); + packet_send(); + buffer_consume(&stderr_buffer, len); + stderr_bytes += len; + } +} + +/* Make packets from buffered stdout data, and buffer it for sending to the + client. */ + +void make_packets_from_stdout_data() +{ + int len; + + /* Send buffered stdout data to the client. */ + while (buffer_len(&stdout_buffer) > 0 && + packet_not_very_much_data_to_write()) + { + len = buffer_len(&stdout_buffer); + if (packet_is_interactive()) + { + if (len > 512) + len = 512; + } + else + { + if (len > 32768) + len = 32768; /* Keep the packets at reasonable size. */ + } + packet_start(SSH_SMSG_STDOUT_DATA); + packet_put_string(buffer_ptr(&stdout_buffer), len); + packet_send(); + buffer_consume(&stdout_buffer, len); + stdout_bytes += len; + } +} + +/* Sleep in select() until we can do something. This will initialize the + select masks. Upon return, the masks will indicate which descriptors + have data or can accept data. Optionally, a maximum time can be specified + for the duration of the wait (0 = infinite). */ + +void wait_until_can_do_something(fd_set *readset, fd_set *writeset, + unsigned int max_time_milliseconds) +{ + struct timeval tv, *tvp; + int ret; + + /* When select fails we restart from here. */ +retry_select: + + /* Initialize select() masks. */ + FD_ZERO(readset); + + /* Read packets from the client unless we have too much buffered stdin + or channel data. */ + if (buffer_len(&stdin_buffer) < 4096 && + channel_not_very_much_buffered_data()) + FD_SET(connection_in, readset); + + /* If there is not too much data already buffered going to the client, + try to get some more data from the program. */ + if (packet_not_very_much_data_to_write()) + { + if (!fdout_eof) + FD_SET(fdout, readset); + if (!fderr_eof) + FD_SET(fderr, readset); + } + + FD_ZERO(writeset); + + /* Set masks for channel descriptors. */ + channel_prepare_select(readset, writeset); + + /* If we have buffered packet data going to the client, mark that + descriptor. */ + if (packet_have_data_to_write()) + FD_SET(connection_out, writeset); + + /* If we have buffered data, try to write some of that data to the + program. */ + if (fdin != -1 && buffer_len(&stdin_buffer) > 0) + FD_SET(fdin, writeset); + + /* Update the maximum descriptor number if appropriate. */ + if (channel_max_fd() > max_fd) + max_fd = channel_max_fd(); + + /* If child has terminated, read as much as is available and then exit. */ + if (child_terminated) + if (max_time_milliseconds == 0) + max_time_milliseconds = 100; + + if (max_time_milliseconds == 0) + tvp = NULL; + else + { + tv.tv_sec = max_time_milliseconds / 1000; + tv.tv_usec = 1000 * (max_time_milliseconds % 1000); + tvp = &tv; + } + + /* Wait for something to happen, or the timeout to expire. */ + ret = select(max_fd + 1, readset, writeset, NULL, tvp); + + if (ret < 0) + { + if (errno != EINTR) + error("select: %.100s", strerror(errno)); + else + goto retry_select; + } +} + +/* Processes input from the client and the program. Input data is stored + in buffers and processed later. */ + +void process_input(fd_set *readset) +{ + int len; + char buf[16384]; + + /* Read and buffer any input data from the client. */ + if (FD_ISSET(connection_in, readset)) + { + len = read(connection_in, buf, sizeof(buf)); + if (len == 0) + fatal("Connection closed by remote host."); + + /* There is a kernel bug on Solaris that causes select to sometimes + wake up even though there is no data available. */ + if (len < 0 && errno == EAGAIN) + len = 0; + + if (len < 0) + fatal("Read error from remote host: %.100s", strerror(errno)); + + /* Buffer any received data. */ + packet_process_incoming(buf, len); + } + + /* Read and buffer any available stdout data from the program. */ + if (!fdout_eof && FD_ISSET(fdout, readset)) + { + len = read(fdout, buf, sizeof(buf)); + if (len <= 0) + fdout_eof = 1; + else + { + buffer_append(&stdout_buffer, buf, len); + fdout_bytes += len; + } + } + + /* Read and buffer any available stderr data from the program. */ + if (!fderr_eof && FD_ISSET(fderr, readset)) + { + len = read(fderr, buf, sizeof(buf)); + if (len <= 0) + fderr_eof = 1; + else + buffer_append(&stderr_buffer, buf, len); + } +} + +/* Sends data from internal buffers to client program stdin. */ + +void process_output(fd_set *writeset) +{ + int len; + + /* Write buffered data to program stdin. */ + if (fdin != -1 && FD_ISSET(fdin, writeset)) + { + len = write(fdin, buffer_ptr(&stdin_buffer), + buffer_len(&stdin_buffer)); + if (len <= 0) + { +#ifdef USE_PIPES + close(fdin); +#else + if (fdout == -1) + close(fdin); + else + shutdown(fdin, SHUT_WR); /* We will no longer send. */ +#endif + fdin = -1; + } + else + { + /* Successful write. Consume the data from the buffer. */ + buffer_consume(&stdin_buffer, len); + /* Update the count of bytes written to the program. */ + stdin_bytes += len; + } + } + + /* Send any buffered packet data to the client. */ + if (FD_ISSET(connection_out, writeset)) + packet_write_poll(); +} + +/* Wait until all buffered output has been sent to the client. + This is used when the program terminates. */ + +void drain_output() +{ + /* Send any buffered stdout data to the client. */ + if (buffer_len(&stdout_buffer) > 0) + { + packet_start(SSH_SMSG_STDOUT_DATA); + packet_put_string(buffer_ptr(&stdout_buffer), + buffer_len(&stdout_buffer)); + packet_send(); + /* Update the count of sent bytes. */ + stdout_bytes += buffer_len(&stdout_buffer); + } + + /* Send any buffered stderr data to the client. */ + if (buffer_len(&stderr_buffer) > 0) + { + packet_start(SSH_SMSG_STDERR_DATA); + packet_put_string(buffer_ptr(&stderr_buffer), + buffer_len(&stderr_buffer)); + packet_send(); + /* Update the count of sent bytes. */ + stderr_bytes += buffer_len(&stderr_buffer); + } + + /* Wait until all buffered data has been written to the client. */ + packet_write_wait(); +} + +/* Performs the interactive session. This handles data transmission between + the client and the program. Note that the notion of stdin, stdout, and + stderr in this function is sort of reversed: this function writes to + stdin (of the child program), and reads from stdout and stderr (of the + child program). */ + +void server_loop(int pid, int fdin_arg, int fdout_arg, int fderr_arg) +{ + int wait_status, wait_pid; /* Status and pid returned by wait(). */ + int waiting_termination = 0; /* Have displayed waiting close message. */ + unsigned int max_time_milliseconds; + unsigned int previous_stdout_buffer_bytes; + unsigned int stdout_buffer_bytes; + int type; + + debug("Entering interactive session."); + + /* Initialize the SIGCHLD kludge. */ + child_pid = pid; + child_terminated = 0; + signal(SIGCHLD, sigchld_handler); + + /* Initialize our global variables. */ + fdin = fdin_arg; + fdout = fdout_arg; + fderr = fderr_arg; + connection_in = packet_get_connection_in(); + connection_out = packet_get_connection_out(); + + previous_stdout_buffer_bytes = 0; + + /* Set approximate I/O buffer size. */ + if (packet_is_interactive()) + buffer_high = 4096; + else + buffer_high = 64 * 1024; + + /* Initialize max_fd to the maximum of the known file descriptors. */ + max_fd = fdin; + if (fdout > max_fd) + max_fd = fdout; + if (fderr != -1 && fderr > max_fd) + max_fd = fderr; + if (connection_in > max_fd) + max_fd = connection_in; + if (connection_out > max_fd) + max_fd = connection_out; + + /* Initialize Initialize buffers. */ + buffer_init(&stdin_buffer); + buffer_init(&stdout_buffer); + buffer_init(&stderr_buffer); + + /* If we have no separate fderr (which is the case when we have a pty - there + we cannot make difference between data sent to stdout and stderr), + indicate that we have seen an EOF from stderr. This way we don\'t + need to check the descriptor everywhere. */ + if (fderr == -1) + fderr_eof = 1; + + /* Main loop of the server for the interactive session mode. */ + for (;;) + { + fd_set readset, writeset; + + /* Process buffered packets from the client. */ + process_buffered_input_packets(); + + /* If we have received eof, and there is no more pending input data, + cause a real eof by closing fdin. */ + if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) + { +#ifdef USE_PIPES + close(fdin); +#else + if (fdout == -1) + close(fdin); + else + shutdown(fdin, SHUT_WR); /* We will no longer send. */ +#endif + fdin = -1; + } + + /* Make packets from buffered stderr data to send to the client. */ + make_packets_from_stderr_data(); + + /* Make packets from buffered stdout data to send to the client. + If there is very little to send, this arranges to not send them + now, but to wait a short while to see if we are getting more data. + This is necessary, as some systems wake up readers from a pty after + each separate character. */ + max_time_milliseconds = 0; + stdout_buffer_bytes = buffer_len(&stdout_buffer); + if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && + stdout_buffer_bytes != previous_stdout_buffer_bytes) + max_time_milliseconds = 10; /* try again after a while */ + else + make_packets_from_stdout_data(); /* Send it now. */ + previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); + + /* Send channel data to the client. */ + if (packet_not_very_much_data_to_write()) + channel_output_poll(); + + /* Bail out of the loop if the program has closed its output descriptors, + and we have no more data to send to the client, and there is no + pending buffered data. */ + if (fdout_eof && fderr_eof && !packet_have_data_to_write() && + buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) + { + if (!channel_still_open()) + goto quit; + if (!waiting_termination) + { + const char *s = + "Waiting for forwarded connections to terminate...\r\n"; + char *cp; + waiting_termination = 1; + buffer_append(&stderr_buffer, s, strlen(s)); + + /* Display list of open channels. */ + cp = channel_open_message(); + buffer_append(&stderr_buffer, cp, strlen(cp)); + xfree(cp); + } + } + + /* Sleep in select() until we can do something. */ + wait_until_can_do_something(&readset, &writeset, + max_time_milliseconds); + + /* Process any channel events. */ + channel_after_select(&readset, &writeset); + + /* Process input from the client and from program stdout/stderr. */ + process_input(&readset); + + /* Process output to the client and to program stdin. */ + process_output(&writeset); + } + + quit: + /* Cleanup and termination code. */ + + /* Wait until all output has been sent to the client. */ + drain_output(); + + debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", + stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); + + /* Free and clear the buffers. */ + buffer_free(&stdin_buffer); + buffer_free(&stdout_buffer); + buffer_free(&stderr_buffer); + + /* Close the file descriptors. */ + if (fdout != -1) + close(fdout); + fdout = -1; + fdout_eof = 1; + if (fderr != -1) + close(fderr); + fderr = -1; + fderr_eof = 1; + if (fdin != -1) + close(fdin); + fdin = -1; + + /* Stop listening for channels; this removes unix domain sockets. */ + channel_stop_listening(); + + /* Wait for the child to exit. Get its exit status. */ + wait_pid = wait(&wait_status); + if (wait_pid < 0) + { + /* It is possible that the wait was handled by SIGCHLD handler. This + may result in either: this call returning with EINTR, or: this + call returning ECHILD. */ + if (child_terminated) + wait_status = child_wait_status; + else + packet_disconnect("wait: %.100s", strerror(errno)); + } + else + { + /* Check if it matches the process we forked. */ + if (wait_pid != pid) + error("Strange, wait returned pid %d, expected %d", wait_pid, pid); + } + + /* We no longer want our SIGCHLD handler to be called. */ + signal(SIGCHLD, SIG_DFL); + + /* Check if it exited normally. */ + if (WIFEXITED(wait_status)) + { + /* Yes, normal exit. Get exit status and send it to the client. */ + debug("Command exited with status %d.", WEXITSTATUS(wait_status)); + packet_start(SSH_SMSG_EXITSTATUS); + packet_put_int(WEXITSTATUS(wait_status)); + packet_send(); + packet_write_wait(); + + /* Wait for exit confirmation. Note that there might be other + packets coming before it; however, the program has already died + so we just ignore them. The client is supposed to respond with + the confirmation when it receives the exit status. */ + do + { + int plen; + type = packet_read(&plen); + } + while (type != SSH_CMSG_EXIT_CONFIRMATION); + + debug("Received exit confirmation."); + return; + } + + /* Check if the program terminated due to a signal. */ + if (WIFSIGNALED(wait_status)) + packet_disconnect("Command terminated on signal %d.", + WTERMSIG(wait_status)); + + /* Some weird exit cause. Just exit. */ + packet_disconnect("wait returned status %04x.", wait_status); + /*NOTREACHED*/ +} + diff --git a/ssh-add.1 b/ssh-add.1 new file mode 100644 index 00000000..ebc07e33 --- /dev/null +++ b/ssh-add.1 @@ -0,0 +1,116 @@ +.\" -*- nroff -*- +.\" +.\" ssh-add.1 +.\" +.\" Author: Tatu Ylonen +.\" +.\" Copyright (c) 1995 Tatu Ylonen , Espoo, Finland +.\" All rights reserved +.\" +.\" Created: Sat Apr 22 23:55:14 1995 ylo +.\" +.\" $Id$ +.\" +.Dd September 25, 1999 +.Dt SSH-ADD 1 +.Os +.Sh NAME +.Nm ssh-add +.Nd adds identities for the authentication agent +.Sh SYNOPSIS +.Nm ssh-add +.Op Fl ldD +.Op Ar +.Sh DESCRIPTION +.Nm +adds identities to the authentication agent, +.Xr ssh-agent 1 . +When run without arguments, it adds the file +.Pa $HOME/.ssh/identity . +Alternative file names can be given on the +command line. If any file requires a passphrase, +.Nm +asks for the passphrase from the user. +The Passphrase it is read from the user's tty. +.Pp +The authentication agent must be running and must be an ancestor of +the current process for +.Nm +to work. +.Pp +The options are as follows: +.Bl -tag -width Ds +.It Fl l +Lists all identities currently represented by the agent. +.It Fl d +Instead of adding the identity, removes the identity from the agent. +.It Fl D +Deletes all identities from the agent. +.El +.Sh FILES +.Bl -tag -width Ds +.Pa $HOME/.ssh/identity +Contains the RSA authentication identity of the user. This file +should not be readable by anyone but the user. +Note that +.Nm +ignores this file if it is accessible by others. +It is possible to +specify a passphrase when generating the key; that passphrase will be +used to encrypt the private part of this file. This is the +default file added by +.Nm +when no other files have been specified. +.Pp +If +.Nm +needs a passphrase, it will read the passphrase from the current +terminal if it was run from a terminal. If +.Nm +does not have a terminal associated with it but +.Ev DISPLAY +is set, it +will open an X11 window to read the passphrase. This is particularly +useful when calling +.Nm +from a +.Pa .Xsession +or related script. (Note that on some machines it +may be necessary to redirect the input from +.Pa /dev/null +to make this work.) +.Sh AUTHOR +Tatu Ylonen +.Pp +OpenSSH +is a derivative of the original (free) ssh 1.2.12 release, but with bugs +removed and newer features re-added. Rapidly after the 1.2.12 release, +newer versions bore successively more restrictive licenses. This version +of OpenSSH +.Bl -bullet +.It +has all components of a restrictive nature (ie. patents, see +.Xr ssl 8 ) +directly removed from the source code; any licensed or patented components +are chosen from +external libraries. +.It +has been updated to support ssh protocol 1.5. +.It +contains added support for +.Xr kerberos 8 +authentication and ticket passing. +.It +supports one-time password authentication with +.Xr skey 1 . +.El +.Pp +The libraries described in +.Xr ssl 8 +are required for proper operation. +.Sh SEE ALSO +.Xr ssh 1 , +.Xr ssh-agent 1 , +.Xr ssh-keygen 1 , +.Xr sshd 8 , +.Xr ssl 8 diff --git a/ssh-add.c b/ssh-add.c new file mode 100644 index 00000000..ce838c4e --- /dev/null +++ b/ssh-add.c @@ -0,0 +1,254 @@ +/* + +ssh-add.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Thu Apr 6 00:52:24 1995 ylo + +Adds an identity to the authentication server, or removes an identity. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "rsa.h" +#include "ssh.h" +#include "xmalloc.h" +#include "authfd.h" + +void +delete_file(const char *filename) +{ + RSA *key; + char *comment; + AuthenticationConnection *ac; + + key = RSA_new(); + if (!load_public_key(filename, key, &comment)) + { + printf("Bad key file %s: %s\n", filename, strerror(errno)); + return; + } + + /* Send the request to the authentication agent. */ + ac = ssh_get_authentication_connection(); + if (!ac) + { + fprintf(stderr, + "Could not open a connection to your authentication agent.\n"); + RSA_free(key); + xfree(comment); + return; + } + if (ssh_remove_identity(ac, key)) + fprintf(stderr, "Identity removed: %s (%s)\n", filename, comment); + else + fprintf(stderr, "Could not remove identity: %s\n", filename); + RSA_free(key); + xfree(comment); + ssh_close_authentication_connection(ac); +} + +void +delete_all() +{ + AuthenticationConnection *ac; + + /* Get a connection to the agent. */ + ac = ssh_get_authentication_connection(); + if (!ac) + { + fprintf(stderr, + "Could not open a connection to your authentication agent.\n"); + return; + } + + /* Send a request to remove all identities. */ + if (ssh_remove_all_identities(ac)) + fprintf(stderr, "All identities removed.\n"); + else + fprintf(stderr, "Failed to remove all identitities.\n"); + + /* Close the connection to the agent. */ + ssh_close_authentication_connection(ac); +} + +void +add_file(const char *filename) +{ + RSA *key; + RSA *public_key; + AuthenticationConnection *ac; + char *saved_comment, *comment, *pass; + int first; + + key = RSA_new(); + public_key = RSA_new(); + if (!load_public_key(filename, public_key, &saved_comment)) + { + printf("Bad key file %s: %s\n", filename, strerror(errno)); + return; + } + RSA_free(public_key); + + pass = xstrdup(""); + first = 1; + while (!load_private_key(filename, pass, key, &comment)) + { + /* Free the old passphrase. */ + memset(pass, 0, strlen(pass)); + xfree(pass); + + /* Ask for a passphrase. */ + if (getenv("DISPLAY") && !isatty(fileno(stdin))) + { + xfree(saved_comment); + return; + } + else + { + if (first) + printf("Need passphrase for %s (%s).\n", filename, saved_comment); + else + printf("Bad passphrase.\n"); + pass = read_passphrase("Enter passphrase: ", 1); + if (strcmp(pass, "") == 0) + { + xfree(saved_comment); + xfree(pass); + return; + } + } + first = 0; + } + memset(pass, 0, strlen(pass)); + xfree(pass); + + xfree(saved_comment); + + /* Send the key to the authentication agent. */ + ac = ssh_get_authentication_connection(); + if (!ac) + { + fprintf(stderr, + "Could not open a connection to your authentication agent.\n"); + RSA_free(key); + xfree(comment); + return; + } + if (ssh_add_identity(ac, key, comment)) + fprintf(stderr, "Identity added: %s (%s)\n", filename, comment); + else + fprintf(stderr, "Could not add identity: %s\n", filename); + RSA_free(key); + xfree(comment); + ssh_close_authentication_connection(ac); +} + +void +list_identities() +{ + AuthenticationConnection *ac; + BIGNUM *e, *n; + int bits, status; + char *comment; + int had_identities; + + ac = ssh_get_authentication_connection(); + if (!ac) + { + fprintf(stderr, "Could not connect to authentication server.\n"); + return; + } + e = BN_new(); + n = BN_new(); + had_identities = 0; + for (status = ssh_get_first_identity(ac, &bits, e, n, &comment); + status; + status = ssh_get_next_identity(ac, &bits, e, n, &comment)) + { + char *buf; + had_identities = 1; + printf("%d ", bits); + buf = BN_bn2dec(e); + assert(buf != NULL); + printf("%s ", buf); + free (buf); + buf = BN_bn2dec(n); + assert(buf != NULL); + printf("%s %s\n", buf, comment); + free (buf); + xfree(comment); + } + BN_clear_free(e); + BN_clear_free(n); + if (!had_identities) + printf("The agent has no identities.\n"); + ssh_close_authentication_connection(ac); +} + +int +main(int ac, char **av) +{ + struct passwd *pw; + char buf[1024]; + int no_files = 1; + int i; + int deleting = 0; + + /* check if RSA support exists */ + if (rsa_alive() == 0) { + extern char *__progname; + + fprintf(stderr, + "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", + __progname); + exit(1); + } + + for (i = 1; i < ac; i++) + { + if (strcmp(av[i], "-l") == 0) + { + list_identities(); + no_files = 0; /* Don't default-add/delete if -l. */ + continue; + } + if (strcmp(av[i], "-d") == 0) + { + deleting = 1; + continue; + } + if (strcmp(av[i], "-D") == 0) + { + delete_all(); + no_files = 0; + continue; + } + no_files = 0; + if (deleting) + delete_file(av[i]); + else + add_file(av[i]); + } + if (no_files) + { + pw = getpwuid(getuid()); + if (!pw) + { + fprintf(stderr, "No user found with uid %d\n", (int)getuid()); + exit(1); + } + snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir, SSH_CLIENT_IDENTITY); + if (deleting) + delete_file(buf); + else + add_file(buf); + } + exit(0); +} diff --git a/ssh-agent.1 b/ssh-agent.1 new file mode 100644 index 00000000..0329b640 --- /dev/null +++ b/ssh-agent.1 @@ -0,0 +1,124 @@ +.\" -*- nroff -*- +.\" +.\" ssh-agent.1 +.\" +.\" Author: Tatu Ylonen +.\" +.\" Copyright (c) 1995 Tatu Ylonen , Espoo, Finland +.\" All rights reserved +.\" +.\" Created: Sat Apr 23 20:10:43 1995 ylo +.\" +.\" $Id$ +.\" +.Dd September 25, 1999 +.Dt SSH-AGENT 1 +.Os +.Sh NAME +.Nm ssh-agent +.Nd authentication agent +.Sh SYNOPSIS +.Nm ssh-agent +.Ar command +.Sh DESCRIPTION +.Nm +is a program to hold authentication private keys. The +idea is that +.Nm +is started in the beginning of an X-session or a login session, and +all other windows or programs are started as children of the ssh-agent +program (the +.Ar command +normally starts X or is the user shell). Programs started under +the agent inherit a connection to the agent, and the agent is +automatically used for RSA authentication when logging to other +machines using +.Xr ssh 1 . +.Pp +The agent initially does not have any private keys. Keys are added +using +.Xr ssh-add 1 . +When executed without arguments, +.Xr ssh-add 1 +adds the +.Pa $HOME/.ssh/identity +file. If the identity has a passphrase, +.Xr ssh-add 1 +asks for the passphrase (using a small X11 application if running +under X11, or from the terminal if running without X). It then sends +the identity to the agent. Several identities can be stored in the +agent; the agent can automatically use any of these identities. +.Ic ssh-add -l +displays the identities currently held by the agent. +.Pp +The idea is that the agent is run in the user's local PC, laptop, or +terminal. Authentication data need not be stored on any other +machine, and authentication passphrases never go over the network. +However, the connection to the agent is forwarded over SSH +remote logins, and the user can thus use the privileges given by the +identities anywhere in the network in a secure way. +.Pp +A connection to the agent is inherited by child programs: +A unix-domain socket is created +.Pq Pa /tmp/ssh-XXXX/agent. , +and the name of this socket is stored in the +.Ev SSH_AUTH_SOCK +environment +variable. The socket is made accessible only to the current user. +This method is easily abused by root or another instance of the same +user. +.Pp +The agent exits automatically when the command given on the command +line terminates. +.Sh FILES +.Bl -tag -width Ds +.It Pa $HOME/.ssh/identity +Contains the RSA authentication identity of the user. This file +should not be readable by anyone but the user. It is possible to +specify a passphrase when generating the key; that passphrase will be +used to encrypt the private part of this file. This file +is not used by +.Nm +but is normally added to the agent using +.Xr ssh-add 1 +at login time. +.It Pa /tmp/ssh-XXXX/agent. , +Unix-domain sockets used to contain the connection to the +authentication agent. These sockets should only be readable by the +owner. The sockets should get automatically removed when the agent +exits. +.Sh AUTHOR +Tatu Ylonen +.Pp +OpenSSH +is a derivative of the original (free) ssh 1.2.12 release, but with bugs +removed and newer features re-added. Rapidly after the 1.2.12 release, +newer versions bore successively more restrictive licenses. This version +of OpenSSH +.Bl -bullet +.It +has all components of a restrictive nature (ie. patents, see +.Xr ssl 8 ) +directly removed from the source code; any licensed or patented components +are chosen from +external libraries. +.It +has been updated to support ssh protocol 1.5. +.It +contains added support for +.Xr kerberos 8 +authentication and ticket passing. +.It +supports one-time password authentication with +.Xr skey 1 . +.El +.Pp +The libraries described in +.Xr ssl 8 +are required for proper operation. +.Sh SEE ALSO +.Xr ssh 1 , +.Xr ssh-add 1 , +.Xr ssh-keygen 1 , +.Xr sshd 8 , +.Xr ssl 8 diff --git a/ssh-agent.c b/ssh-agent.c new file mode 100644 index 00000000..d07e3b81 --- /dev/null +++ b/ssh-agent.c @@ -0,0 +1,572 @@ +/* + +ssh-agent.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Mar 29 03:46:59 1995 ylo + +The authentication agent program. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include "rsa.h" +#include "authfd.h" +#include "buffer.h" +#include "bufaux.h" +#include "xmalloc.h" +#include "packet.h" +#include "getput.h" +#include "mpaux.h" + +#include + +typedef struct +{ + int fd; + enum { AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION } type; + Buffer input; + Buffer output; +} SocketEntry; + +unsigned int sockets_alloc = 0; +SocketEntry *sockets = NULL; + +typedef struct +{ + RSA *key; + char *comment; +} Identity; + +unsigned int num_identities = 0; +Identity *identities = NULL; + +int max_fd = 0; + +/* pid of shell == parent of agent */ +int parent_pid = -1; + +/* pathname and directory for AUTH_SOCKET */ +char socket_name[1024]; +char socket_dir[1024]; + +void +process_request_identity(SocketEntry *e) +{ + Buffer msg; + int i; + + buffer_init(&msg); + buffer_put_char(&msg, SSH_AGENT_RSA_IDENTITIES_ANSWER); + buffer_put_int(&msg, num_identities); + for (i = 0; i < num_identities; i++) + { + buffer_put_int(&msg, BN_num_bits(identities[i].key->n)); + buffer_put_bignum(&msg, identities[i].key->e); + buffer_put_bignum(&msg, identities[i].key->n); + buffer_put_string(&msg, identities[i].comment, + strlen(identities[i].comment)); + } + buffer_put_int(&e->output, buffer_len(&msg)); + buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); + buffer_free(&msg); +} + +void +process_authentication_challenge(SocketEntry *e) +{ + int i, pub_bits, len; + BIGNUM *pub_e, *pub_n, *challenge; + Buffer msg; + MD5_CTX md; + unsigned char buf[32], mdbuf[16], session_id[16]; + unsigned int response_type; + + buffer_init(&msg); + pub_e = BN_new(); + pub_n = BN_new(); + challenge = BN_new(); + pub_bits = buffer_get_int(&e->input); + buffer_get_bignum(&e->input, pub_e); + buffer_get_bignum(&e->input, pub_n); + buffer_get_bignum(&e->input, challenge); + if (buffer_len(&e->input) == 0) + { + /* Compatibility code for old servers. */ + memset(session_id, 0, 16); + response_type = 0; + } + else + { + /* New code. */ + buffer_get(&e->input, (char *)session_id, 16); + response_type = buffer_get_int(&e->input); + } + for (i = 0; i < num_identities; i++) + if (pub_bits == BN_num_bits(identities[i].key->n) && + BN_cmp(pub_e, identities[i].key->e) == 0 && + BN_cmp(pub_n, identities[i].key->n) == 0) + { + /* Decrypt the challenge using the private key. */ + rsa_private_decrypt(challenge, challenge, identities[i].key); + + /* Compute the desired response. */ + switch (response_type) + { + case 0: /* As of protocol 1.0 */ + /* This response type is no longer supported. */ + log("Compatibility with ssh protocol 1.0 no longer supported."); + buffer_put_char(&msg, SSH_AGENT_FAILURE); + goto send; + + case 1: /* As of protocol 1.1 */ + /* The response is MD5 of decrypted challenge plus session id. */ + len = BN_num_bytes(challenge); + assert(len <= 32 && len); + memset(buf, 0, 32); + BN_bn2bin(challenge, buf + 32 - len); + MD5_Init(&md); + MD5_Update(&md, buf, 32); + MD5_Update(&md, session_id, 16); + MD5_Final(mdbuf, &md); + break; + + default: + fatal("process_authentication_challenge: bad response_type %d", + response_type); + break; + } + + /* Send the response. */ + buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE); + for (i = 0; i < 16; i++) + buffer_put_char(&msg, mdbuf[i]); + + goto send; + } + /* Unknown identity. Send failure. */ + buffer_put_char(&msg, SSH_AGENT_FAILURE); + send: + buffer_put_int(&e->output, buffer_len(&msg)); + buffer_append(&e->output, buffer_ptr(&msg), + buffer_len(&msg)); + buffer_free(&msg); + BN_clear_free(pub_e); + BN_clear_free(pub_n); + BN_clear_free(challenge); +} + +void +process_remove_identity(SocketEntry *e) +{ + unsigned int bits; + unsigned int i; + BIGNUM *dummy, *n; + + dummy = BN_new(); + n = BN_new(); + + /* Get the key from the packet. */ + bits = buffer_get_int(&e->input); + buffer_get_bignum(&e->input, dummy); + buffer_get_bignum(&e->input, n); + + /* Check if we have the key. */ + for (i = 0; i < num_identities; i++) + if (BN_cmp(identities[i].key->n, n) == 0) + { + /* We have this key. Free the old key. Since we don\'t want to leave + empty slots in the middle of the array, we actually free the + key there and copy data from the last entry. */ + RSA_free(identities[i].key); + xfree(identities[i].comment); + if (i < num_identities - 1) + identities[i] = identities[num_identities - 1]; + num_identities--; + BN_clear_free(dummy); + BN_clear_free(n); + + /* Send success. */ + buffer_put_int(&e->output, 1); + buffer_put_char(&e->output, SSH_AGENT_SUCCESS); + return; + } + /* We did not have the key. */ + BN_clear(dummy); + BN_clear(n); + + /* Send failure. */ + buffer_put_int(&e->output, 1); + buffer_put_char(&e->output, SSH_AGENT_FAILURE); +} + +/* Removes all identities from the agent. */ + +void +process_remove_all_identities(SocketEntry *e) +{ + unsigned int i; + + /* Loop over all identities and clear the keys. */ + for (i = 0; i < num_identities; i++) + { + RSA_free(identities[i].key); + xfree(identities[i].comment); + } + + /* Mark that there are no identities. */ + num_identities = 0; + + /* Send success. */ + buffer_put_int(&e->output, 1); + buffer_put_char(&e->output, SSH_AGENT_SUCCESS); + return; +} + +/* Adds an identity to the agent. */ + +void +process_add_identity(SocketEntry *e) +{ + RSA *k; + int i; + BIGNUM *aux; + BN_CTX *ctx; + + if (num_identities == 0) + identities = xmalloc(sizeof(Identity)); + else + identities = xrealloc(identities, (num_identities + 1) * sizeof(Identity)); + + identities[num_identities].key = RSA_new(); + k = identities[num_identities].key; + buffer_get_int(&e->input); /* bits */ + k->n = BN_new(); + buffer_get_bignum(&e->input, k->n); + k->e = BN_new(); + buffer_get_bignum(&e->input, k->e); + k->d = BN_new(); + buffer_get_bignum(&e->input, k->d); + k->iqmp = BN_new(); + buffer_get_bignum(&e->input, k->iqmp); + /* SSH and SSL have p and q swapped */ + k->q = BN_new(); + buffer_get_bignum(&e->input, k->q); /* p */ + k->p = BN_new(); + buffer_get_bignum(&e->input, k->p); /* q */ + + /* Generate additional parameters */ + aux = BN_new(); + ctx = BN_CTX_new(); + + BN_sub(aux, k->q, BN_value_one()); + k->dmq1 = BN_new(); + BN_mod(k->dmq1, k->d, aux, ctx); + + BN_sub(aux, k->p, BN_value_one()); + k->dmp1 = BN_new(); + BN_mod(k->dmp1, k->d, aux, ctx); + + BN_clear_free(aux); + BN_CTX_free(ctx); + + identities[num_identities].comment = buffer_get_string(&e->input, NULL); + + /* Check if we already have the key. */ + for (i = 0; i < num_identities; i++) + if (BN_cmp(identities[i].key->n, k->n) == 0) + { + /* We already have this key. Clear and free the new data and + return success. */ + RSA_free(k); + xfree(identities[num_identities].comment); + + /* Send success. */ + buffer_put_int(&e->output, 1); + buffer_put_char(&e->output, SSH_AGENT_SUCCESS); + return; + } + + /* Increment the number of identities. */ + num_identities++; + + /* Send a success message. */ + buffer_put_int(&e->output, 1); + buffer_put_char(&e->output, SSH_AGENT_SUCCESS); +} + +void +process_message(SocketEntry *e) +{ + unsigned int msg_len; + unsigned int type; + unsigned char *cp; + if (buffer_len(&e->input) < 5) + return; /* Incomplete message. */ + cp = (unsigned char *)buffer_ptr(&e->input); + msg_len = GET_32BIT(cp); + if (msg_len > 256 * 1024) + { + shutdown(e->fd, SHUT_RDWR); + close(e->fd); + e->type = AUTH_UNUSED; + return; + } + if (buffer_len(&e->input) < msg_len + 4) + return; + buffer_consume(&e->input, 4); + type = buffer_get_char(&e->input); + + switch (type) + { + case SSH_AGENTC_REQUEST_RSA_IDENTITIES: + process_request_identity(e); + break; + case SSH_AGENTC_RSA_CHALLENGE: + process_authentication_challenge(e); + break; + case SSH_AGENTC_ADD_RSA_IDENTITY: + process_add_identity(e); + break; + case SSH_AGENTC_REMOVE_RSA_IDENTITY: + process_remove_identity(e); + break; + case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: + process_remove_all_identities(e); + break; + default: + /* Unknown message. Respond with failure. */ + error("Unknown message %d", type); + buffer_clear(&e->input); + buffer_put_int(&e->output, 1); + buffer_put_char(&e->output, SSH_AGENT_FAILURE); + break; + } +} + +void +new_socket(int type, int fd) +{ + unsigned int i, old_alloc; + if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) + error("fcntl O_NONBLOCK: %s", strerror(errno)); + + if (fd > max_fd) + max_fd = fd; + + for (i = 0; i < sockets_alloc; i++) + if (sockets[i].type == AUTH_UNUSED) + { + sockets[i].fd = fd; + sockets[i].type = type; + buffer_init(&sockets[i].input); + buffer_init(&sockets[i].output); + return; + } + old_alloc = sockets_alloc; + sockets_alloc += 10; + if (sockets) + sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0])); + else + sockets = xmalloc(sockets_alloc * sizeof(sockets[0])); + for (i = old_alloc; i < sockets_alloc; i++) + sockets[i].type = AUTH_UNUSED; + sockets[old_alloc].type = type; + sockets[old_alloc].fd = fd; + buffer_init(&sockets[old_alloc].input); + buffer_init(&sockets[old_alloc].output); +} + +void +prepare_select(fd_set *readset, fd_set *writeset) +{ + unsigned int i; + for (i = 0; i < sockets_alloc; i++) + switch (sockets[i].type) + { + case AUTH_SOCKET: + case AUTH_CONNECTION: + FD_SET(sockets[i].fd, readset); + if (buffer_len(&sockets[i].output) > 0) + FD_SET(sockets[i].fd, writeset); + break; + case AUTH_UNUSED: + break; + default: + fatal("Unknown socket type %d", sockets[i].type); + break; + } +} + +void after_select(fd_set *readset, fd_set *writeset) +{ + unsigned int i; + int len, sock; + char buf[1024]; + struct sockaddr_un sunaddr; + + for (i = 0; i < sockets_alloc; i++) + switch (sockets[i].type) + { + case AUTH_UNUSED: + break; + case AUTH_SOCKET: + if (FD_ISSET(sockets[i].fd, readset)) + { + len = sizeof(sunaddr); + sock = accept(sockets[i].fd, (struct sockaddr *)&sunaddr, &len); + if (sock < 0) + { + perror("accept from AUTH_SOCKET"); + break; + } + new_socket(AUTH_CONNECTION, sock); + } + break; + case AUTH_CONNECTION: + if (buffer_len(&sockets[i].output) > 0 && + FD_ISSET(sockets[i].fd, writeset)) + { + len = write(sockets[i].fd, buffer_ptr(&sockets[i].output), + buffer_len(&sockets[i].output)); + if (len <= 0) + { + shutdown(sockets[i].fd, SHUT_RDWR); + close(sockets[i].fd); + sockets[i].type = AUTH_UNUSED; + break; + } + buffer_consume(&sockets[i].output, len); + } + if (FD_ISSET(sockets[i].fd, readset)) + { + len = read(sockets[i].fd, buf, sizeof(buf)); + if (len <= 0) + { + shutdown(sockets[i].fd, SHUT_RDWR); + close(sockets[i].fd); + sockets[i].type = AUTH_UNUSED; + break; + } + buffer_append(&sockets[i].input, buf, len); + process_message(&sockets[i]); + } + break; + default: + fatal("Unknown type %d", sockets[i].type); + } +} + +void +check_parent_exists(int sig) +{ + if (kill(parent_pid, 0) < 0) + { + /* printf("Parent has died - Authentication agent exiting.\n"); */ + exit(1); + } + signal(SIGALRM, check_parent_exists); + alarm(10); +} + +void cleanup_socket(void) { + remove(socket_name); + rmdir(socket_dir); +} + +int +main(int ac, char **av) +{ + fd_set readset, writeset; + int sock; + struct sockaddr_un sunaddr; + + /* check if RSA support exists */ + if (rsa_alive() == 0) { + extern char *__progname; + fprintf(stderr, + "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", + __progname); + exit(1); + } + + if (ac < 2) + { + fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION); + fprintf(stderr, "Usage: %s command\n", av[0]); + exit(1); + } + + parent_pid = getpid(); + + /* Create private directory for agent socket */ + strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir); + if (mkdtemp(socket_dir) == NULL) { + perror("mkdtemp: private socket dir"); + exit(1); + } + snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir, parent_pid); + + /* Fork, and have the parent execute the command. The child continues as + the authentication agent. */ + if (fork() != 0) + { /* Parent - execute the given command. */ + setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1); + execvp(av[1], av + 1); + perror(av[1]); + exit(1); + } + + if (atexit(cleanup_socket) < 0) { + perror("atexit"); + cleanup_socket(); + exit(1); + } + + sock = socket(AF_UNIX, SOCK_STREAM, 0); + if (sock < 0) + { + perror("socket"); + exit(1); + } + memset(&sunaddr, 0, sizeof(sunaddr)); + sunaddr.sun_family = AF_UNIX; + strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); + if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) + { + perror("bind"); + exit(1); + } + if (listen(sock, 5) < 0) + { + perror("listen"); + exit(1); + } + new_socket(AUTH_SOCKET, sock); + signal(SIGALRM, check_parent_exists); + alarm(10); + + signal(SIGINT, SIG_IGN); + while (1) + { + FD_ZERO(&readset); + FD_ZERO(&writeset); + prepare_select(&readset, &writeset); + if (select(max_fd + 1, &readset, &writeset, NULL, NULL) < 0) + { + if (errno == EINTR) + continue; + perror("select"); + exit(1); + } + after_select(&readset, &writeset); + } + /*NOTREACHED*/ +} diff --git a/ssh-keygen.1 b/ssh-keygen.1 new file mode 100644 index 00000000..7daab9b2 --- /dev/null +++ b/ssh-keygen.1 @@ -0,0 +1,155 @@ +.\" -*- nroff -*- +.\" +.\" ssh-keygen.1 +.\" +.\" Author: Tatu Ylonen +.\" +.\" Copyright (c) 1995 Tatu Ylonen , Espoo, Finland +.\" All rights reserved +.\" +.\" Created: Sat Apr 22 23:55:14 1995 ylo +.\" +.\" $Id$ +.\" +.Dd September 25, 1999 +.Dt SSH-KEYGEN 1 +.Os +.Sh NAME +.Nm ssh-keygen +.Nd authentication key generation +.Sh SYNOPSIS +.Nm ssh-keygen +.Op Fl q +.Op Fl b Ar bits +.Op Fl N Ar new_passphrase +.Op Fl C Ar comment +.Nm ssh-keygen +.Fl p +.Op Fl P Ar old_passphrase +.Op Fl N Ar new_passphrase +.Nm ssh-keygen +.Fl c +.Op Fl P Ar passphrase +.Op Fl C Ar comment +.Sh DESCRIPTION +.Nm +generates and manages authentication keys for +.Xr ssh 1 . +Normally each user wishing to use SSH +with RSA authentication runs this once to create the authentication +key in +.Pa $HOME/.ssh/identity . +Additionally, the system administrator may use this to generate host keys. +.Pp +Normally this program generates the key and asks for a file in which +to store the private key. The public key is stored in a file with the +same name but +.Dq .pub +appended. The program also asks for a +passphrase. The passphrase may be empty to indicate no passphrase +(host keys must have empty passphrase), or it may be a string of +arbitrary length. Good passphrases are 10-30 characters long and are +not simple sentences or otherwise easily guessable (English +prose has only 1-2 bits of entropy per word, and provides very bad +passphrases). The passphrase can be changed later by using the +.Fl p +option. +.Pp +There is no way to recover a lost passphrase. If the passphrase is +lost or forgotten, you will have to generate a new key and copy the +corresponding public key to other machines. +.Pp +There is also a comment field in the key file that is only for +convenience to the user to help identify the key. The comment can +tell what the key is for, or whatever is useful. The comment is +initialized to +.Dq user@host +when the key is created, but can be changed using the +.Fl c +option. +.Pp +The options are as follows: +.Bl -tag -width Ds +.It Fl b Ar bits +Specifies the number of bits in the key to create. Minimum is 512 +bits. Generally 1024 bits is considered sufficient, and key sizes +above that no longer improve security but make things slower. The +default is 1024 bits. +.It Fl c +Requests changing the comment in the private and public key files. +The program will prompt for the file containing the private keys, for +passphrase if the key has one, and for the new comment. +.It Fl p +Requests changing the passphrase of a private key file instead of +creating a new private key. The program will prompt for the file +containing the private key, for the old passphrase, and twice for the +new passphrase. +.It Fl q +Silence +.Nm ssh-keygen . +Used by +.Pa /etc/rc +when creating a new key. +.It Fl C Ar comment +Provides the new comment. +.It Fl N Ar new_passphrase +Provides the new passphrase. +.It Fl P Ar passphrase +Provides the (old) passphrase. +.El +.Sh FILES +.Bl -tag -width Ds +.It Pa $HOME/.ssh/random_seed +Used for seeding the random number generator. This file should not be +readable by anyone but the user. This file is created the first time +the program is run, and is updated every time. +.It Pa $HOME/.ssh/identity +Contains the RSA authentication identity of the user. This file +should not be readable by anyone but the user. It is possible to +specify a passphrase when generating the key; that passphrase will be +used to encrypt the private part of this file using 3DES. This file +is not automatically accessed by +.Nm +but it is offered as the default file for the private key. +.It Pa $HOME/.ssh/identity.pub +Contains the public key for authentication. The contents of this file +should be added to +.Pa $HOME/.ssh/authorized_keys +on all machines +where you wish to log in using RSA authentication. There is no +need to keep the contents of this file secret. +.Sh AUTHOR +Tatu Ylonen +.Pp +OpenSSH +is a derivative of the original (free) ssh 1.2.12 release, but with bugs +removed and newer features re-added. Rapidly after the 1.2.12 release, +newer versions bore successively more restrictive licenses. This version +of OpenSSH +.Bl -bullet +.It +has all components of a restrictive nature (ie. patents, see +.Xr ssl 8 ) +directly removed from the source code; any licensed or patented components +are chosen from +external libraries. +.It +has been updated to support ssh protocol 1.5. +.It +contains added support for +.Xr kerberos 8 +authentication and ticket passing. +.It +supports one-time password authentication with +.Xr skey 1 . +.El +.Pp +The libraries described in +.Xr ssl 8 +are required for proper operation. +.Sh SEE ALSO +.Xr ssh 1 , +.Xr ssh-add 1 , +.Xr ssh-agent 1, +.Xr sshd 8 , +.Xr ssl 8 diff --git a/ssh-keygen.c b/ssh-keygen.c new file mode 100644 index 00000000..96b87ced --- /dev/null +++ b/ssh-keygen.c @@ -0,0 +1,552 @@ +/* + +ssh-keygen.c + +Author: Tatu Ylonen + +Copyright (c) 1994 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Mon Mar 27 02:26:40 1995 ylo + +Identity and host key generation and maintenance. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "rsa.h" +#include "ssh.h" +#include "xmalloc.h" + +/* Generated private key. */ +RSA *private_key; + +/* Generated public key. */ +RSA *public_key; + +/* Number of bits in the RSA key. This value can be changed on the command + line. */ +int bits = 1024; + +/* Flag indicating that we just want to change the passphrase. This can be + set on the command line. */ +int change_passphrase = 0; + +/* Flag indicating that we just want to change the comment. This can be set + on the command line. */ +int change_comment = 0; + +int quiet = 0; + +/* This is set to the identity file name if given on the command line. */ +char *identity_file = NULL; + +/* This is set to the passphrase if given on the command line. */ +char *identity_passphrase = NULL; + +/* This is set to the new passphrase if given on the command line. */ +char *identity_new_passphrase = NULL; + +/* This is set to the new comment if given on the command line. */ +char *identity_comment = NULL; + +/* Perform changing a passphrase. The argument is the passwd structure + for the current user. */ + +void +do_change_passphrase(struct passwd *pw) +{ + char buf[1024], *comment; + char *old_passphrase, *passphrase1, *passphrase2; + struct stat st; + RSA *private_key; + + /* Read key file name. */ + if (identity_file != NULL) { + strncpy(buf, identity_file, sizeof(buf)); + buf[sizeof(buf) - 1] = '\0'; + } else { + printf("Enter file in which the key is ($HOME/%s): ", SSH_CLIENT_IDENTITY); + fflush(stdout); + if (fgets(buf, sizeof(buf), stdin) == NULL) + exit(1); + if (strchr(buf, '\n')) + *strchr(buf, '\n') = 0; + if (strcmp(buf, "") == 0) + snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir, SSH_CLIENT_IDENTITY); + } + + /* Check if the file exists. */ + if (stat(buf, &st) < 0) + { + perror(buf); + exit(1); + } + + /* Try to load the public key from the file the verify that it is + readable and of the proper format. */ + public_key = RSA_new(); + if (!load_public_key(buf, public_key, NULL)) + { + printf("%s is not a valid key file.\n", buf); + exit(1); + } + /* Clear the public key since we are just about to load the whole file. */ + RSA_free(public_key); + + /* Try to load the file with empty passphrase. */ + private_key = RSA_new(); + if (!load_private_key(buf, "", private_key, &comment)) { + /* Read passphrase from the user. */ + if (identity_passphrase) + old_passphrase = xstrdup(identity_passphrase); + else + old_passphrase = read_passphrase("Enter old passphrase: ", 1); + /* Try to load using the passphrase. */ + if (!load_private_key(buf, old_passphrase, private_key, &comment)) + { + memset(old_passphrase, 0, strlen(old_passphrase)); + xfree(old_passphrase); + printf("Bad passphrase.\n"); + exit(1); + } + /* Destroy the passphrase. */ + memset(old_passphrase, 0, strlen(old_passphrase)); + xfree(old_passphrase); + } + printf("Key has comment '%s'\n", comment); + + /* Ask the new passphrase (twice). */ + if (identity_new_passphrase) + { + passphrase1 = xstrdup(identity_new_passphrase); + passphrase2 = NULL; + } + else + { + passphrase1 = + read_passphrase("Enter new passphrase (empty for no passphrase): ", 1); + passphrase2 = read_passphrase("Enter same passphrase again: ", 1); + + /* Verify that they are the same. */ + if (strcmp(passphrase1, passphrase2) != 0) + { + memset(passphrase1, 0, strlen(passphrase1)); + memset(passphrase2, 0, strlen(passphrase2)); + xfree(passphrase1); + xfree(passphrase2); + printf("Pass phrases do not match. Try again.\n"); + exit(1); + } + /* Destroy the other copy. */ + memset(passphrase2, 0, strlen(passphrase2)); + xfree(passphrase2); + } + + /* Save the file using the new passphrase. */ + if (!save_private_key(buf, passphrase1, private_key, comment)) + { + printf("Saving the key failed: %s: %s.\n", + buf, strerror(errno)); + memset(passphrase1, 0, strlen(passphrase1)); + xfree(passphrase1); + RSA_free(private_key); + xfree(comment); + exit(1); + } + /* Destroy the passphrase and the copy of the key in memory. */ + memset(passphrase1, 0, strlen(passphrase1)); + xfree(passphrase1); + RSA_free(private_key); /* Destroys contents */ + xfree(comment); + + printf("Your identification has been saved with the new passphrase.\n"); + exit(0); +} + +/* Change the comment of a private key file. */ + +void +do_change_comment(struct passwd *pw) +{ + char buf[1024], new_comment[1024], *comment; + RSA *private_key; + char *passphrase; + struct stat st; + FILE *f; + char *tmpbuf; + + /* Read key file name. */ + if (identity_file) + { + strncpy(buf, identity_file, sizeof(buf)); + buf[sizeof(buf) - 1] = '\0'; + } + else + { + printf("Enter file in which the key is ($HOME/%s): ", + SSH_CLIENT_IDENTITY); + fflush(stdout); + if (fgets(buf, sizeof(buf), stdin) == NULL) + exit(1); + if (strchr(buf, '\n')) + *strchr(buf, '\n') = 0; + if (strcmp(buf, "") == 0) + snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir, SSH_CLIENT_IDENTITY); + } + + /* Check if the file exists. */ + if (stat(buf, &st) < 0) + { + perror(buf); + exit(1); + } + + /* Try to load the public key from the file the verify that it is + readable and of the proper format. */ + public_key = RSA_new(); + if (!load_public_key(buf, public_key, NULL)) + { + printf("%s is not a valid key file.\n", buf); + exit(1); + } + + private_key = RSA_new(); + /* Try to load the file with empty passphrase. */ + if (load_private_key(buf, "", private_key, &comment)) + passphrase = xstrdup(""); + else + { + /* Read passphrase from the user. */ + if (identity_passphrase) + passphrase = xstrdup(identity_passphrase); + else + if (identity_new_passphrase) + passphrase = xstrdup(identity_new_passphrase); + else + passphrase = read_passphrase("Enter passphrase: ", 1); + /* Try to load using the passphrase. */ + if (!load_private_key(buf, passphrase, private_key, &comment)) + { + memset(passphrase, 0, strlen(passphrase)); + xfree(passphrase); + printf("Bad passphrase.\n"); + exit(1); + } + } + printf("Key now has comment '%s'\n", comment); + + if (identity_comment) + { + strncpy(new_comment, identity_comment, sizeof(new_comment)); + new_comment[sizeof(new_comment) - 1] = '\0'; + } + else + { + printf("Enter new comment: "); + fflush(stdout); + if (!fgets(new_comment, sizeof(new_comment), stdin)) + { + memset(passphrase, 0, strlen(passphrase)); + RSA_free(private_key); + exit(1); + } + + /* Remove terminating newline from comment. */ + if (strchr(new_comment, '\n')) + *strchr(new_comment, '\n') = 0; + } + + /* Save the file using the new passphrase. */ + if (!save_private_key(buf, passphrase, private_key, new_comment)) + { + printf("Saving the key failed: %s: %s.\n", + buf, strerror(errno)); + memset(passphrase, 0, strlen(passphrase)); + xfree(passphrase); + RSA_free(private_key); + xfree(comment); + exit(1); + } + + /* Destroy the passphrase and the private key in memory. */ + memset(passphrase, 0, strlen(passphrase)); + xfree(passphrase); + RSA_free(private_key); + + /* Save the public key in text format in a file with the same name but + .pub appended. */ + strcat(buf, ".pub"); + f = fopen(buf, "w"); + if (!f) + { + printf("Could not save your public key in %s\n", buf); + exit(1); + } + fprintf(f, "%d ", BN_num_bits(public_key->n)); + tmpbuf = BN_bn2dec(public_key->e); + fprintf(f, "%s ", tmpbuf); + free (tmpbuf); + tmpbuf = BN_bn2dec(public_key->n); + fprintf(f, "%s %s\n", tmpbuf, new_comment); + free (tmpbuf); + fclose(f); + + xfree(comment); + + printf("The comment in your key file has been changed.\n"); + exit(0); +} + +/* Main program for key management. */ + +int +main(int ac, char **av) +{ + char buf[16384], buf2[1024], *passphrase1, *passphrase2; + struct passwd *pw; + char *tmpbuf; + int opt; + struct stat st; + FILE *f; + char hostname[MAXHOSTNAMELEN]; + extern int optind; + extern char *optarg; + + /* check if RSA support exists */ + if (rsa_alive() == 0) { + extern char *__progname; + + fprintf(stderr, + "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", + __progname); + exit(1); + } + + /* Get user\'s passwd structure. We need this for the home directory. */ + pw = getpwuid(getuid()); + if (!pw) + { + printf("You don't exist, go away!\n"); + exit(1); + } + + /* Create ~/.ssh directory if it doesn\'t already exist. */ + snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir, SSH_USER_DIR); + if (stat(buf, &st) < 0) + if (mkdir(buf, 0755) < 0) + error("Could not create directory '%s'.", buf); + + /* Parse command line arguments. */ + while ((opt = getopt(ac, av, "qpcb:f:P:N:C:")) != EOF) + { + switch (opt) + { + case 'b': + bits = atoi(optarg); + if (bits < 512 || bits > 32768) + { + printf("Bits has bad value.\n"); + exit(1); + } + break; + + case 'p': + change_passphrase = 1; + break; + + case 'c': + change_comment = 1; + break; + + case 'f': + identity_file = optarg; + break; + + case 'P': + identity_passphrase = optarg; + break; + + case 'N': + identity_new_passphrase = optarg; + break; + + case 'C': + identity_comment = optarg; + break; + + case 'q': + quiet = 1; + break; + + case '?': + default: + printf("ssh-keygen version %s\n", SSH_VERSION); + printf("Usage: %s [-b bits] [-p] [-c] [-f file] [-P pass] [-N new-pass] [-C comment]\n", av[0]); + exit(1); + } + } + if (optind < ac) + { + printf("Too many arguments.\n"); + exit(1); + } + if (change_passphrase && change_comment) + { + printf("Can only have one of -p and -c.\n"); + exit(1); + } + + /* If the user requested to change the passphrase, do it now. This + function never returns. */ + if (change_passphrase) + do_change_passphrase(pw); + + /* If the user requested to change the comment, do it now. This function + never returns. */ + if (change_comment) + do_change_comment(pw); + + arc4random_stir(); + + if (quiet) + rsa_set_verbose(0); + + /* Generate the rsa key pair. */ + private_key = RSA_new(); + public_key = RSA_new(); + rsa_generate_key(private_key, public_key, bits); + + ask_file_again: + + /* Ask for a file to save the key in. */ + if (identity_file) + { + strncpy(buf, identity_file, sizeof(buf)); + buf[sizeof(buf) - 1] = '\0'; + } + else + { + printf("Enter file in which to save the key ($HOME/%s): ", + SSH_CLIENT_IDENTITY); + fflush(stdout); + if (fgets(buf, sizeof(buf), stdin) == NULL) + exit(1); + if (strchr(buf, '\n')) + *strchr(buf, '\n') = 0; + if (strcmp(buf, "") == 0) + snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir, SSH_CLIENT_IDENTITY); + } + + /* If the file aready exists, ask the user to confirm. */ + if (stat(buf, &st) >= 0) + { + printf("%s already exists.\n", buf); + printf("Overwrite (y/n)? "); + fflush(stdout); + if (fgets(buf2, sizeof(buf2), stdin) == NULL) + exit(1); + if (buf2[0] != 'y' && buf2[0] != 'Y') + exit(1); + } + + /* Ask for a passphrase (twice). */ + if (identity_passphrase) + passphrase1 = xstrdup(identity_passphrase); + else + if (identity_new_passphrase) + passphrase1 = xstrdup(identity_new_passphrase); + else + { + passphrase_again: + passphrase1 = + read_passphrase("Enter passphrase (empty for no passphrase): ", 1); + passphrase2 = read_passphrase("Enter same passphrase again: ", 1); + if (strcmp(passphrase1, passphrase2) != 0) + { + /* The passphrases do not match. Clear them and retry. */ + memset(passphrase1, 0, strlen(passphrase1)); + memset(passphrase2, 0, strlen(passphrase2)); + xfree(passphrase1); + xfree(passphrase2); + printf("Passphrases do not match. Try again.\n"); + goto passphrase_again; + } + /* Clear the other copy of the passphrase. */ + memset(passphrase2, 0, strlen(passphrase2)); + xfree(passphrase2); + } + + /* Create default commend field for the passphrase. The user can later + edit this field. */ + if (identity_comment) + { + strlcpy(buf2, identity_comment, sizeof(buf2)); + } + else + { + if (gethostname(hostname, sizeof(hostname)) < 0) + { + perror("gethostname"); + exit(1); + } + snprintf(buf2, sizeof buf2, "%s@%s", pw->pw_name, hostname); + } + + /* Save the key with the given passphrase and comment. */ + if (!save_private_key(buf, passphrase1, private_key, buf2)) + { + printf("Saving the key failed: %s: %s.\n", + buf, strerror(errno)); + memset(passphrase1, 0, strlen(passphrase1)); + xfree(passphrase1); + goto ask_file_again; + } + /* Clear the passphrase. */ + memset(passphrase1, 0, strlen(passphrase1)); + xfree(passphrase1); + + /* Clear the private key and the random number generator. */ + RSA_free(private_key); + arc4random_stir(); + + if (!quiet) + printf("Your identification has been saved in %s.\n", buf); + + /* Display the public key on the screen. */ + if (!quiet) { + printf("Your public key is:\n"); + printf("%d ", BN_num_bits(public_key->n)); + tmpbuf = BN_bn2dec(public_key->e); + printf("%s ", tmpbuf); + free(tmpbuf); + tmpbuf = BN_bn2dec(public_key->n); + printf("%s %s\n", tmpbuf, buf2); + free(tmpbuf); + } + + /* Save the public key in text format in a file with the same name but + .pub appended. */ + strcat(buf, ".pub"); + f = fopen(buf, "w"); + if (!f) + { + printf("Could not save your public key in %s\n", buf); + exit(1); + } + fprintf(f, "%d ", BN_num_bits(public_key->n)); + tmpbuf = BN_bn2dec(public_key->e); + fprintf(f, "%s ", tmpbuf); + free(tmpbuf); + tmpbuf = BN_bn2dec(public_key->n); + fprintf(f, "%s %s\n", tmpbuf, buf2); + free(tmpbuf); + fclose(f); + + if (!quiet) + printf("Your public key has been saved in %s\n", buf); + + exit(0); +} diff --git a/ssh.1 b/ssh.1 new file mode 100644 index 00000000..865d07c8 --- /dev/null +++ b/ssh.1 @@ -0,0 +1,966 @@ +.\" -*- nroff -*- +.\" +.\" ssh.1.in +.\" +.\" Author: Tatu Ylonen +.\" +.\" Copyright (c) 1995 Tatu Ylonen , Espoo, Finland +.\" All rights reserved +.\" +.\" Created: Sat Apr 22 21:55:14 1995 ylo +.\" +.\" $Id$ +.\" +.Dd September 25, 1999 +.Dt SSH 1 +.Os +.Sh NAME +.Nm ssh +.Nd OpenSSH secure shell client (remote login program) +.Sh SYNOPSIS +.Nm ssh +.Op Fl l Ar login_name +.Op Ar hostname | user@hostname +.Op Ar command +.Pp +.Nm ssh +.Op Fl afgknqtvxCPX +.Op Fl c Ar blowfish | 3des +.Op Fl e Ar escape_char +.Op Fl i Ar identity_file +.Op Fl l Ar login_name +.Op Fl o Ar option +.Op Fl p Ar port +.Oo Fl L Xo +.Sm off +.Ar host : +.Ar port : +.Ar hostport +.Sm on +.Xc +.Oc +.Oo Fl R Xo +.Sm off +.Ar host : +.Ar port : +.Ar hostport +.Sm on +.Xc +.Oc +.Op Ar hostname | user@hostname +.Op Ar command +.Sh DESCRIPTION +.Nm +(Secure Shell) is a program for logging into a remote machine and for +executing commands on a remote machine. It is intended to replace +rlogin and rsh, and provide secure encrypted communications between +two untrusted hosts over an insecure network. X11 connections and +arbitrary TCP/IP ports can also be forwarded over the secure channel. +.Pp +.Nm +connects and logs into the specified +.Ar hostname . +The user must prove +his/her identity to the remote machine using one of several methods. +.Pp +First, if the machine the user logs in from is listed in +.Pa /etc/hosts.equiv +or +.Pa /etc/shosts.equiv +on the remote machine, and the user names are +the same on both sides, the user is immediately permitted to log in. +Second, if +.Pa \&.rhosts +or +.Pa \&.shosts +exists in the user's home directory on the +remote machine and contains a line containing the name of the client +machine and the name of the user on that machine, the user is +permitted to log in. This form of authentication alone is normally not +allowed by the server because it is not secure. +.Pp +The second (and primary) authentication method is the +.Pa rhosts +or +.Pa hosts.equiv +method combined with RSA-based host authentication. It +means that if the login would be permitted by +.Pa \&.rhosts , +.Pa \&.shosts , +.Pa /etc/hosts.equiv , +or +.Pa /etc/shosts.equiv , +and if additionally the server can verify the client's +host key (see +.Pa /etc/ssh_known_hosts +in the +.Sx FILES +section), only then login is +permitted. This authentication method closes security holes due to IP +spoofing, DNS spoofing and routing spoofing. [Note to the +administrator: +.Pa /etc/hosts.equiv , +.Pa \&.rhosts , +and the rlogin/rsh protocol in general, are inherently insecure and should be +disabled if security is desired.] +.Pp +As a third authentication method, +.Nm +supports RSA based authentication. +The scheme is based on public-key cryptography: there are cryptosystems +where encryption and decryption are done using separate keys, and it +is not possible to derive the decryption key from the encryption key. +RSA is one such system. The idea is that each user creates a public/private +key pair for authentication purposes. The +server knows the public key, and only the user knows the private key. +The file +.Pa $HOME/.ssh/authorized_keys +lists the public keys that are permitted for logging +in. When the user logs in, the +.Nm +program tells the server which key pair it would like to use for +authentication. The server checks if this key is permitted, and if +so, sends the user (actually the +.Nm +program running on behalf of the user) a challenge, a random number, +encrypted by the user's public key. The challenge can only be +decrypted using the proper private key. The user's client then decrypts the +challenge using the private key, proving that he/she knows the private +key but without disclosing it to the server. +.Pp +.Nm +implements the RSA authentication protocol automatically. The user +creates his/her RSA key pair by running +.Xr ssh-keygen 1 . +This stores the private key in +.Pa \&.ssh/identity +and the public key in +.Pa \&.ssh/identity.pub +in the user's home directory. The user should then +copy the +.Pa identity.pub +to +.Pa \&.ssh/authorized_keys +in his/her home directory on the remote machine (the +.Pa authorized_keys +file corresponds to the conventional +.Pa \&.rhosts +file, and has one key +per line, though the lines can be very long). After this, the user +can log in without giving the password. RSA authentication is much +more secure than rhosts authentication. +.Pp +The most convenient way to use RSA authentication may be with an +authentication agent. See +.Xr ssh-agent 1 +for more information. +.Pp +If other authentication methods fail, +.Nm +prompts the user for a password. The password is sent to the remote +host for checking; however, since all communications are encrypted, +the password cannot be seen by someone listening on the network. +.Pp +When the user's identity has been accepted by the server, the server +either executes the given command, or logs into the machine and gives +the user a normal shell on the remote machine. All communication with +the remote command or shell will be automatically encrypted. +.Pp +If a pseudo-terminal has been allocated (normal login session), the +user can disconnect with +.Ic ~. , +and suspend +.Nm +with +.Ic ~^Z . +All forwarded connections can be listed with +.Ic ~# +and if +the session blocks waiting for forwarded X11 or TCP/IP +connections to terminate, it can be backgrounded with +.Ic ~& +(this should not be used while the user shell is active, as it can cause the +shell to hang). All available escapes can be listed with +.Ic ~? . +.Pp +A single tilde character can be sent as +.Ic ~~ +(or by following the tilde by a character other than those described above). +The escape character must always follow a newline to be interpreted as +special. The escape character can be changed in configuration files +or on the command line. +.Pp +If no pseudo tty has been allocated, the +session is transparent and can be used to reliably transfer binary +data. On most systems, setting the escape character to +.Dq none +will also make the session transparent even if a tty is used. +.Pp +The session terminates when the command or shell in on the remote +machine exists and all X11 and TCP/IP connections have been closed. +The exit status of the remote program is returned as the exit status +of +.Nm ssh . +.Pp +If the user is using X11 (the +.Ev DISPLAY +environment variable is set), the connection to the X11 display is +automatically forwarded to the remote side in such a way that any X11 +programs started from the shell (or command) will go through the +encrypted channel, and the connection to the real X server will be made +from the local machine. The user should not manually set +.Ev DISPLAY . +Forwarding of X11 connections can be +configured on the command line or in configuration files. +.Pp +The +.Ev DISPLAY +value set by +.Nm +will point to the server machine, but with a display number greater +than zero. This is normal, and happens because +.Nm +creates a +.Dq proxy +X server on the server machine for forwarding the +connections over the encrypted channel. +.Pp +.Nm +will also automatically set up Xauthority data on the server machine. +For this purpose, it will generate a random authorization cookie, +store it in Xauthority on the server, and verify that any forwarded +connections carry this cookie and replace it by the real cookie when +the connection is opened. The real authentication cookie is never +sent to the server machine (and no cookies are sent in the plain). +.Pp +If the user is using an authentication agent, the connection to the agent +is automatically forwarded to the remote side unless disabled on +command line or in a configuration file. +.Pp +Forwarding of arbitrary TCP/IP connections over the secure channel can +be specified either on command line or in a configuration file. One +possible application of TCP/IP forwarding is a secure connection to an +electronic purse; another is going trough firewalls. +.Pp +.Nm +automatically maintains and checks a database containing RSA-based +identifications for all hosts it has ever been used with. The +database is stored in +.Pa \&.ssh/known_hosts +in the user's home directory. Additionally, the file +.Pa /etc/ssh_known_hosts +is automatically checked for known hosts. Any new hosts are +automatically added to the user's file. If a host's identification +ever changes, +.Nm +warns about this and disables password authentication to prevent a +trojan horse from getting the user's password. Another purpose of +this mechanism is to prevent man-in-the-middle attacks which could +otherwise be used to circumvent the encryption. The +.Cm StrictHostKeyChecking +option (see below) can be used to prevent logins to machines whose +host key is not known or has changed. +.Sh OPTIONS +.Bl -tag -width Ds +.It Fl a +Disables forwarding of the authentication agent connection. This may +also be specified on a per-host basis in the configuration file. +.It Fl c Ar blowfish|3des +Selects the cipher to use for encrypting the session. +.Ar 3des +is used by default. It is believed to be secure. +.Ar 3des +(triple-des) is an encrypt-decrypt-encrypt triple with three different keys. +It is presumably more secure than the +.Ar des +cipher which is no longer supported in ssh. +.Ar blowfish +is a fast block cipher, it appears very secure and is much faster than +.Ar 3des . +.It Fl e Ar ch|^ch|none +Sets the escape character for sessions with a pty (default: +.Ql ~ ) . +The escape character is only recognized at the beginning of a line. The +escape character followed by a dot +.Pq Ql \&. +closes the connection, followed +by control-Z suspends the connection, and followed by itself sends the +escape character once. Setting the character to +.Dq none +disables any escapes and makes the session fully transparent. +.It Fl f +Requests +.Nm +to go to background after authentication. This is useful +if +.Nm +is going to ask for passwords or passphrases, but the user +wants it in the background. This implies +.Fl n . +The recommended way to start X11 programs at a remote site is with +something like +.Ic ssh -f host xterm . +.It Fl i Ar identity_file +Selects the file from which the identity (private key) for +RSA authentication is read. Default is +.Pa \&.ssh/identity +in the user's home directory. Identity files may also be specified on +a per-host basis in the configuration file. It is possible to have +multiple +.Fl i +options (and multiple identities specified in +configuration files). +.It Fl g +Allows remote hosts to connect to local forwarded ports. +.It Fl k +Disables forwarding of Kerberos tickets and AFS tokens. This may +also be specified on a per-host basis in the configuration file. +.It Fl l Ar login_name +Specifies the user to log in as on the remote machine. This may also +be specified on a per-host basis in the configuration file. +.It Fl n +Redirects stdin from +.Pa /dev/null +(actually, prevents reading from stdin). +This must be used when +.Nm +is run in the background. A common trick is to use this to run X11 +programs in a remote machine. For example, +.Ic ssh -n shadows.cs.hut.fi emacs & +will start an emacs on shadows.cs.hut.fi, and the X11 +connection will be automatically forwarded over an encrypted channel. +The +.Nm +program will be put in the background. +(This does not work if +.Nm +needs to ask for a password or passphrase; see also the +.Fl f +option.) +.It Fl o Ar option +Can be used to give options in the format used in the config file. +This is useful for specifying options for which there is no separate +command-line flag. The option has the same format as a line in the +configuration file. +.It Fl p Ar port +Port to connect to on the remote host. This can be specified on a +per-host basis in the configuration file. +.It Fl P +Use a non-privileged port for outgoing connections. +This can be used if your firewall does +not permit connections from privileged ports. +Note that this option turns of +.Cm RhostsAuthentication +and +.Cm RhostsRSAAuthentication . +.It Fl q +Quiet mode. Causes all warning and diagnostic messages to be +suppressed. Only fatal errors are displayed. +.It Fl t +Force pseudo-tty allocation. This can be used to execute arbitary +screen-based programs on a remote machine, which can be very useful +e.g. when implementing menu services. +.It Fl v +Verbose mode. Causes +.Nm +to print debugging messages about its progress. This is helpful in +debugging connection, authentication, and configuration problems. +The verbose mode is also used to display +.Xr skey 1 +challenges, if the user entered "s/key" as password. +.It Fl x +Disables X11 forwarding. This can also be specified on a per-host +basis in a configuration file. +.It Fl X +Enables X11 forwarding. +.It Fl C +Requests compression of all data (including stdin, stdout, stderr, and +data for forwarded X11 and TCP/IP connections). The compression +algorithm is the same used by gzip, and the +.Dq level +can be controlled by the +.Cm CompressionLevel +option (see below). Compression is desirable on modem lines and other +slow connections, but will only slow down things on fast networks. +The default value can be set on a host-by-host basis in the +configuration files; see the +.Cm Compress +option below. +.It Fl L Ar port:host:hostport +Specifies that the given port on the local (client) host is to be +forwarded to the given host and port on the remote side. This works +by allocating a socket to listen to +.Ar port +on the local side, and whenever a connection is made to this port, the +connection is forwarded over the secure channel, and a connection is +made to +.Ar host:hostport +from the remote machine. Port forwardings can also be specified in the +configuration file. Only root can forward privileged ports. +.It Fl R Ar port:host:hostport +Specifies that the given port on the remote (server) host is to be +forwarded to the given host and port on the local side. This works +by allocating a socket to listen to +.Ar port +on the remote side, and whenever a connection is made to this port, the +connection is forwarded over the secure channel, and a connection is +made to +.Ar host:hostport +from the local machine. Port forwardings can also be specified in the +configuration file. Privileged ports can be forwarded only when +logging in as root on the remote machine. +.El +.Sh CONFIGURATION FILES +.Nm +obtains configuration data from the following sources (in this order): +command line options, user's configuration file +.Pq Pa $HOME/.ssh/config , +and system-wide configuration file +.Pq Pa /etc/ssh_config . +For each parameter, the first obtained value +will be used. The configuration files contain sections bracketed by +"Host" specifications, and that section is only applied for hosts that +match one of the patterns given in the specification. The matched +host name is the one given on the command line. +.Pp +Since the first obtained value for each parameter is used, more +host-specific declarations should be given near the beginning of the +file, and general defaults at the end. +.Pp +The configuration file has the following format: +.Pp +Empty lines and lines starting with +.Ql # +are comments. +.Pp +Otherwise a line is of the format +.Dq keyword arguments . +The possible +keywords and their meanings are as follows (note that the +configuration files are case-sensitive): +.Bl -tag -width Ds +.It Cm Host +Restricts the following declarations (up to the next +.Cm Host +keyword) to be only for those hosts that match one of the patterns +given after the keyword. +.Ql \&* +and +.Ql ? +can be used as wildcards in the +patterns. A single +.Ql \&* +as a pattern can be used to provide global +defaults for all hosts. The host is the +.Ar hostname +argument given on the command line (i.e., the name is not converted to +a canonicalized host name before matching). +.It Cm AFSTokenPassing +Specifies whether to pass AFS tokens to remote host. The argument to +this keyword must be +.Dq yes +or +.Dq no . +.It Cm BatchMode +If set to +.Dq yes , +passphrase/password querying will be disabled. This +option is useful in scripts and other batch jobs where you have no +user to supply the password. The argument must be +.Dq yes +or +.Dq no . +.It Cm Cipher +Specifies the cipher to use for encrypting the session. Currently, +.Dq blowfish , +and +.Dq 3des +are supported. The default is +.Dq 3des . +.It Cm Compression +Specifies whether to use compression. The argument must be +.Dq yes +or +.Dq no . +.It Cm CompressionLevel +Specifies the compression level to use if compression is enable. The +argument must be an integer from 1 (fast) to 9 (slow, best). The +default level is 6, which is good for most applications. The meaning +of the values is the same as in GNU GZIP. +.It Cm ConnectionAttempts +Specifies the number of tries (one per second) to make before falling +back to rsh or exiting. The argument must be an integer. This may be +useful in scripts if the connection sometimes fails. +.It Cm EscapeChar +Sets the escape character (default: +.Ql ~ ) . +The escape character can also +be set on the command line. The argument should be a single +character, +.Ql ^ +followed by a letter, or +.Dq none +to disable the escape +character entirely (making the connection transparent for binary +data). +.It Cm FallBackToRsh +Specifies that if connecting via +.Nm +fails due to a connection refused error (there is no +.Xr sshd 8 +listening on the remote host), +.Xr rsh 1 +should automatically be used instead (after a suitable warning about +the session being unencrypted). The argument must be +.Dq yes +or +.Dq no . +.It Cm ForwardAgent +Specifies whether the connection to the authentication agent (if any) +will be forwarded to the remote machine. The argument must be +.Dq yes +or +.Dq no . +.It Cm ForwardX11 +Specifies whether X11 connections will be automatically redirected +over the secure channel and +.Ev DISPLAY +set. The argument must be +.Dq yes +or +.Dq no . +.It Cm GatewayPorts +Specifies whether remote hosts are allowed to connect to local +forwarded ports. +The argument must be +.Dq yes +or +.Dq no . +The default is +.Dq no . +.It Cm GlobalKnownHostsFile +Specifies a file to use instead of +.Pa /etc/ssh_known_hosts . +.It Cm HostName +Specifies the real host name to log into. This can be used to specify +nicnames or abbreviations for hosts. Default is the name given on the +command line. Numeric IP addresses are also permitted (both on the +command line and in +.Cm HostName +specifications). +.It Cm IdentityFile +Specifies the file from which the user's RSA authentication identity +is read (default +.Pa .ssh/identity +in the user's home directory). +Additionally, any identities represented by the authentication agent +will be used for authentication. The file name may use the tilde +syntax to refer to a user's home directory. It is possible to have +multiple identity files specified in configuration files; all these +identities will be tried in sequence. +.It Cm KeepAlive +Specifies whether the system should send keepalive messages to the +other side. If they are sent, death of the connection or crash of one +of the machines will be properly noticed. However, this means that +connections will die if the route is down temporarily, and some people +find it annoying. +.Pp +The default is +.Dq yes +(to send keepalives), and the client will notice +if the network goes down or the remote host dies. This is important +in scripts, and many users want it too. +.Pp +To disable keepalives, the value should be set to +.Dq no +in both the server and the client configuration files. +.It Cm KerberosAuthentication +Specifies whether Kerberos authentication will be used. The argument to +this keyword must be +.Dq yes +or +.Dq no . +.It Cm KerberosTgtPassing +Specifies whether a Kerberos TGT will be forwarded to the server. This +will only work if the Kerberos server is actually an AFS kaserver. The +argument to this keyword must be +.Dq yes +or +.Dq no . +.It Cm LocalForward +Specifies that a TCP/IP port on the local machine be forwarded over +the secure channel to given host:port from the remote machine. The +first argument must be a port number, and the second must be +host:port. Multiple forwardings may be specified, and additional +forwardings can be given on the command line. Only the root can +forward privileged ports. +.It Cm PasswordAuthentication +Specifies whether to use password authentication. The argument to +this keyword must be +.Dq yes +or +.Dq no . +.It Cm NumberOfPasswordPrompts +Specifies the number of password prompts before giving up. The +argument to this keyword must be an integer. Default is 3. +.It Cm Port +Specifies the port number to connect on the remote host. Default is +22. +.It Cm ProxyCommand +Specifies the command to use to connect to the server. The command +string extends to the end of the line, and is executed with /bin/sh. +In the command string, %h will be substituted by the host name to +connect and %p by the port. The command can be basically anything, +and should read from its stdin and write to its stdout. It should +eventually connect an +.Xr sshd 8 +server running on some machine, or execute +.Ic sshd -i +somewhere. Host key management will be done using the +HostName of the host being connected (defaulting to the name typed by +the user). +.Pp +.It Cm RemoteForward +Specifies that a TCP/IP port on the remote machine be forwarded over +the secure channel to given host:port from the local machine. The +first argument must be a port number, and the second must be +host:port. Multiple forwardings may be specified, and additional +forwardings can be given on the command line. Only the root can +forward privileged ports. +.It Cm RhostsAuthentication +Specifies whether to try rhosts based authentication. Note that this +declaration only affects the client side and has no effect whatsoever +on security. Disabling rhosts authentication may reduce +authentication time on slow connections when rhosts authentication is +not used. Most servers do not permit RhostsAuthentication because it +is not secure (see RhostsRSAAuthentication). The argument to this +keyword must be +.Dq yes +or +.Dq no . +.It Cm RhostsRSAAuthentication +Specifies whether to try rhosts based authentication with RSA host +authentication. This is the primary authentication method for most +sites. The argument must be +.Dq yes +or +.Dq no . +.It Cm RSAAuthentication +Specifies whether to try RSA authentication. The argument to this +keyword must be +.Dq yes +or +.Dq no . +RSA authentication will only be +attempted if the identity file exists, or an authentication agent is +running. +.It Cm CheckHostIP +If this flag is set to +.Dq yes , +ssh will additionally check the host ip address in the +.Pa known_hosts +file. This allows ssh to detect if a host key changed due to DNS spoofing. +If the option is set to +.Dq no , +the check will not be executed. +.It Cm StrictHostKeyChecking +If this flag is set to +.Dq yes , +.Nm +ssh will never automatically add host keys to the +.Pa $HOME/.ssh/known_hosts +file, and refuses to connect hosts whose host key has changed. This +provides maximum protection against trojan horse attacks. However, it +can be somewhat annoying if you don't have good +.Pa /etc/ssh_known_hosts +files installed and frequently +connect new hosts. Basically this option forces the user to manually +add any new hosts. Normally this option is disabled, and new hosts +will automatically be added to the known host files. The host keys of +known hosts will be verified automatically in either case. The +argument must be +.Dq yes +or +.Dq no . +.It Cm User +Specifies the user to log in as. This can be useful if you have a +different user name in different machines. This saves the trouble of +having to remember to give the user name on the command line. +.It Cm UserKnownHostsFile +Specifies a file to use instead of +.Pa $HOME/.ssh/known_hosts . +.It Cm UsePrivilegedPort +Specifies whether to use a privileged port for outgoing connections. +The argument must be +.Dq yes +or +.Dq no . +The default is +.Dq yes . +Note that setting this option to +.Dq no +turns of +.Cm RhostsAuthentication +and +.Cm RhostsRSAAuthentication . +.It Cm UseRsh +Specifies that rlogin/rsh should be used for this host. It is +possible that the host does not at all support the +.Nm +protocol. This causes +.Nm +to immediately exec +.Xr rsh 1 . +All other options (except +.Cm HostName ) +are ignored if this has been specified. The argument must be +.Dq yes +or +.Dq no . +.Sh ENVIRONMENT +.Nm +will normally set the following environment variables: +.Bl -tag -width Ds +.It Ev DISPLAY +The +.Ev DISPLAY +variable indicates the location of the X11 server. It is +automatically set by +.Nm +to point to a value of the form +.Dq hostname:n +where hostname indicates +the host where the shell runs, and n is an integer >= 1. Ssh uses +this special value to forward X11 connections over the secure +channel. The user should normally not set DISPLAY explicitly, as that +will render the X11 connection insecure (and will require the user to +manually copy any required authorization cookies). +.It Ev HOME +Set to the path of the user's home directory. +.It Ev LOGNAME +Synonym for +.Ev USER ; +set for compatibility with systems that use this variable. +.It Ev MAIL +Set to point the user's mailbox. +.It Ev PATH +Set to the default +.Ev PATH , +as specified when compiling +.Nm ssh . +.It Ev SSH_AUTH_SOCK +indicates the path of a unix-domain socket used to communicate with the +agent. +.It Ev SSH_CLIENT +Identifies the client end of the connection. The variable contains +three space-separated values: client ip-address, client port number, +and server port number. +.It Ev SSH_TTY +This is set to the name of the tty (path to the device) associated +with the current shell or command. If the current session has no tty, +this variable is not set. +.It Ev TZ +The timezone variable is set to indicate the present timezone if it +was set when the daemon was started (e.i., the daemon passes the value +on to new connections). +.It Ev USER +Set to the name of the user logging in. +.El +.Pp +Additionally, +.Nm +reads +.Pa $HOME/.ssh/environment , +and adds lines of the format +.Dq VARNAME=value +to the environment. +.Sh FILES +.Bl -tag -width $HOME/.ssh/known_hosts +.It Pa $HOME/.ssh/known_hosts +Records host keys for all hosts the user has logged into (that are not +in +.Pa /etc/ssh_known_hosts ) . +See +.Xr sshd 8 . +.It Pa $HOME/.ssh/random_seed +Used for seeding the random number generator. This file contains +sensitive data and should read/write for the user and not accessible +for others. This file is created the first time the program is run +and updated automatically. The user should never need to read or +modify this file. +.It Pa $HOME/.ssh/identity +Contains the RSA authentication identity of the user. This file +contains sensitive data and should be readable by the user but not +accessible by others (read/write/execute). +Note that +.Nm +ignores this file if it is accessible by others. +It is possible to specify a passphrase when +generating the key; the passphrase will be used to encrypt the +sensitive part of this file using 3DES. +.It Pa $HOME/.ssh/identity.pub +Contains the public key for authentication (public part of the +identity file in human-readable form). The contents of this file +should be added to +.Pa $HOME/.ssh/authorized_keys +on all machines +where you wish to log in using RSA authentication. This file is not +sensitive and can (but need not) be readable by anyone. This file is +never used automatically and is not necessary; it is only provided for +the convenience of the user. +.It Pa $HOME/.ssh/config +This is the per-user configuration file. The format of this file is +described above. This file is used by the +.Nm +client. This file does not usually contain any sensitive information, +but the recommended permissions are read/write for the user, and not +accessible by others. +.It Pa $HOME/.ssh/authorized_keys +Lists the RSA keys that can be used for logging in as this user. The +format of this file is described in the +.Xr sshd 8 +manual page. In the simplest form the format is the same as the .pub +identity files (that is, each line contains the number of bits in +modulus, public exponent, modulus, and comment fields, separated by +spaces). This file is not highly sensitive, but the recommended +permissions are read/write for the user, and not accessible by others. +.It Pa /etc/ssh_known_hosts +Systemwide list of known host keys. This file should be prepared by the +system administrator to contain the public host keys of all machines in the +organization. This file should be world-readable. This file contains +public keys, one per line, in the following format (fields separated +by spaces): system name, number of bits in modulus, public exponent, +modulus, and optional comment field. When different names are used +for the same machine, all such names should be listed, separated by +commas. The format is described on the +.Xr sshd 8 +manual page. +.Pp +The canonical system name (as returned by name servers) is used by +.Xr sshd 8 +to verify the client host when logging in; other names are needed because +.Nm +does not convert the user-supplied name to a canonical name before +checking the key, because someone with access to the name servers +would then be able to fool host authentication. +.It Pa /etc/ssh_config +Systemwide configuration file. This file provides defaults for those +values that are not specified in the user's configuration file, and +for those users who do not have a configuration file. This file must +be world-readable. +.It Pa $HOME/.rhosts +This file is used in +.Pa \&.rhosts +authentication to list the +host/user pairs that are permitted to log in. (Note that this file is +also used by rlogin and rsh, which makes using this file insecure.) +Each line of the file contains a host name (in the canonical form +returned by name servers), and then a user name on that host, +separated by a space. One some machines this file may need to be +world-readable if the user's home directory is on a NFS partition, +because +.Xr sshd 8 +reads it as root. Additionally, this file must be owned by the user, +and must not have write permissions for anyone else. The recommended +permission for most machines is read/write for the user, and not +accessible by others. +.Pp +Note that by default +.Xr sshd 8 +will be installed so that it requires successful RSA host +authentication before permitting \s+2.\s0rhosts authentication. If your +server machine does not have the client's host key in +.Pa /etc/ssh_known_hosts , +you can store it in +.Pa $HOME/.ssh/known_hosts . +The easiest way to do this is to +connect back to the client from the server machine using ssh; this +will automatically add the host key inxi +.Pa $HOME/.ssh/known_hosts . +.It Pa $HOME/.shosts +This file is used exactly the same way as +.Pa \&.rhosts . +The purpose for +having this file is to be able to use rhosts authentication with +.Nm +without permitting login with +.Xr rlogin 1 +or +.Xr rsh 1 . +.It Pa /etc/hosts.equiv +This file is used during +.Pa \&.rhosts authentication. It contains +canonical hosts names, one per line (the full format is described on +the +.Xr sshd 8 +manual page). If the client host is found in this file, login is +automatically permitted provided client and server user names are the +same. Additionally, successful RSA host authentication is normally +required. This file should only be writable by root. +.It Pa /etc/shosts.equiv +This file is processed exactly as +.Pa /etc/hosts.equiv . +This file may be useful to permit logins using +.Nm +but not using rsh/rlogin. +.It Pa /etc/sshrc +Commands in this file are executed by +.Nm +when the user logs in just before the user's shell (or command) is started. +See the +.Xr sshd 8 +manual page for more information. +.It Pa $HOME/.ssh/rc +Commands in this file are executed by +.Nm +when the user logs in just before the user's shell (or command) is +started. +See the +.Xr sshd 8 +manual page for more information. +.It Pa libcrypto.so.X.1 +A version of this library which includes support for the RSA algorithm +is required for proper operation. +.Sh AUTHOR +Tatu Ylonen +.Pp +Issues can be found from the SSH WWW home page: +.Pp +.Dl http://www.cs.hut.fi/ssh +.Pp +OpenSSH +is a derivative of the original (free) ssh 1.2.12 release, but with bugs +removed and newer features re-added. Rapidly after the 1.2.12 release, +newer versions bore successively more restrictive licenses. This version +of OpenSSH +.Bl -bullet +.It +has all components of a restrictive nature (ie. patents, see +.Xr ssl 8 ) +directly removed from the source code; any licensed or patented components +are chosen from +external libraries. +.It +has been updated to support ssh protocol 1.5. +.It +contains added support for +.Xr kerberos 8 +authentication and ticket passing. +.It +supports one-time password authentication with +.Xr skey 1 . +.El +.Pp +The libraries described in +.Xr ssl 8 +are required for proper operation. +.Sh SEE ALSO +.Xr rlogin 1 , +.Xr rsh 1 , +.Xr scp 1 , +.Xr ssh-add 1 , +.Xr ssh-agent 1 , +.Xr ssh-keygen 1 , +.Xr telnet 1 , +.Xr sshd 8 , +.Xr ssl 8 diff --git a/ssh.c b/ssh.c new file mode 100644 index 00000000..9ec18336 --- /dev/null +++ b/ssh.c @@ -0,0 +1,809 @@ +/* + +ssh.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Mar 18 16:36:11 1995 ylo + +Ssh client program. This program can be used to log into a remote machine. +The software supports strong authentication, encryption, and forwarding +of X11, TCP/IP, and authentication connections. + +Modified to work with SSL by Niels Provos in Canada. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "xmalloc.h" +#include "ssh.h" +#include "packet.h" +#include "buffer.h" +#include "authfd.h" +#include "readconf.h" +#include "uidswap.h" + +/* Flag indicating whether debug mode is on. This can be set on the + command line. */ +int debug_flag = 0; + +/* Flag indicating whether quiet mode is on. */ +int quiet_flag = 0; + +/* Flag indicating whether to allocate a pseudo tty. This can be set on the + command line, and is automatically set if no command is given on the command + line. */ +int tty_flag = 0; + +/* Flag indicating that nothing should be read from stdin. This can be set + on the command line. */ +int stdin_null_flag = 0; + +/* Flag indicating that ssh should fork after authentication. This is useful + so that the pasphrase can be entered manually, and then ssh goes to the + background. */ +int fork_after_authentication_flag = 0; + +/* General data structure for command line options and options configurable + in configuration files. See readconf.h. */ +Options options; + +/* Name of the host we are connecting to. This is the name given on the + command line, or the HostName specified for the user-supplied name + in a configuration file. */ +char *host; + +/* socket address the host resolves to */ +struct sockaddr_in hostaddr; + +/* Flag to indicate that we have received a window change signal which has + not yet been processed. This will cause a message indicating the new + window size to be sent to the server a little later. This is volatile + because this is updated in a signal handler. */ +volatile int received_window_change_signal = 0; + +/* Value of argv[0] (set in the main program). */ +char *av0; + +/* Flag indicating whether we have a valid host private key loaded. */ +int host_private_key_loaded = 0; + +/* Host private key. */ +RSA *host_private_key = NULL; + +/* Original real UID. */ +uid_t original_real_uid; + +/* Prints a help message to the user. This function never returns. */ + +void +usage() +{ + fprintf(stderr, "Usage: %s [options] host [command]\n", av0); + fprintf(stderr, "Options:\n"); + fprintf(stderr, " -l user Log in using this user name.\n"); + fprintf(stderr, " -n Redirect input from /dev/null.\n"); + fprintf(stderr, " -a Disable authentication agent forwarding.\n"); +#ifdef AFS + fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); +#endif /* AFS */ + fprintf(stderr, " -x Disable X11 connection forwarding.\n"); + fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n"); + fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); + fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); + fprintf(stderr, " -V Display version number only.\n"); + fprintf(stderr, " -P Don't allocate a privileged port.\n"); + fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); + fprintf(stderr, " -f Fork into background after authentication.\n"); + fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); + + fprintf(stderr, " -c cipher Select encryption algorithm: " + "``3des'', " + "``blowfish''\n"); + fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); + fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); + fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); + fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0); + fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); + fprintf(stderr, " -C Enable compression.\n"); + fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); + fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); + exit(1); +} + +/* Connects to the given host using rsh (or prints an error message and exits + if rsh is not available). This function never returns. */ + +void +rsh_connect(char *host, char *user, Buffer *command) +{ + char *args[10]; + int i; + + log("Using rsh. WARNING: Connection will not be encrypted."); + /* Build argument list for rsh. */ + i = 0; + args[i++] = _PATH_RSH; + args[i++] = host; /* may have to come after user on some systems */ + if (user) + { + args[i++] = "-l"; + args[i++] = user; + } + if (buffer_len(command) > 0) + { + buffer_append(command, "\0", 1); + args[i++] = buffer_ptr(command); + } + args[i++] = NULL; + if (debug_flag) + { + for (i = 0; args[i]; i++) + { + if (i != 0) + fprintf(stderr, " "); + fprintf(stderr, "%s", args[i]); + } + fprintf(stderr, "\n"); + } + execv(_PATH_RSH, args); + perror(_PATH_RSH); + exit(1); +} + +/* Main program for the ssh client. */ + +uid_t original_real_uid; + +int +main(int ac, char **av) +{ + int i, opt, optind, type, exit_status, ok, fwd_port, fwd_host_port, authfd; + char *optarg, *cp, buf[256]; + Buffer command; + struct winsize ws; + struct stat st; + struct passwd *pw, pwcopy; + int interactive = 0, dummy; + uid_t original_effective_uid; + int plen; + + /* Save the original real uid. It will be needed later (uid-swapping may + clobber the real uid). */ + original_real_uid = getuid(); + original_effective_uid = geteuid(); + + /* If we are installed setuid root be careful to not drop core. */ + if (original_real_uid != original_effective_uid) + { + struct rlimit rlim; + rlim.rlim_cur = rlim.rlim_max = 0; + if (setrlimit(RLIMIT_CORE, &rlim) < 0) + fatal("setrlimit failed: %.100s", strerror(errno)); + } + + /* Use uid-swapping to give up root privileges for the duration of option + processing. We will re-instantiate the rights when we are ready to + create the privileged port, and will permanently drop them when the + port has been created (actually, when the connection has been made, as + we may need to create the port several times). */ + temporarily_use_uid(original_real_uid); + + /* Set our umask to something reasonable, as some files are created with + the default umask. This will make them world-readable but writable + only by the owner, which is ok for all files for which we don't set + the modes explicitly. */ + umask(022); + + /* Save our own name. */ + av0 = av[0]; + + /* Initialize option structure to indicate that no values have been set. */ + initialize_options(&options); + + /* Parse command-line arguments. */ + host = NULL; + + /* If program name is not one of the standard names, use it as host name. */ + if (strchr(av0, '/')) + cp = strrchr(av0, '/') + 1; + else + cp = av0; + if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 && + strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0) + host = cp; + + for (optind = 1; optind < ac; optind++) + { + if (av[optind][0] != '-') + { + if (host) + break; + if ((cp = strchr(av[optind], '@'))) { + options.user = av[optind]; + *cp = '\0'; + host = ++cp; + } + else + host = av[optind]; + continue; + } + opt = av[optind][1]; + if (!opt) + usage(); + if (strchr("eilcpLRo", opt)) /* options with arguments */ + { + optarg = av[optind] + 2; + if (strcmp(optarg, "") == 0) + { + if (optind >= ac - 1) + usage(); + optarg = av[++optind]; + } + } + else + { + if (av[optind][2]) + usage(); + optarg = NULL; + } + switch (opt) + { + case 'n': + stdin_null_flag = 1; + break; + + case 'f': + fork_after_authentication_flag = 1; + stdin_null_flag = 1; + break; + + case 'x': + options.forward_x11 = 0; + break; + + case 'X': + options.forward_x11 = 1; + break; + + case 'g': + options.gateway_ports = 1; + break; + + case 'P': + options.use_privileged_port = 0; + break; + + case 'a': + options.forward_agent = 0; + break; +#ifdef AFS + case 'k': + options.kerberos_tgt_passing = 0; + options.afs_token_passing = 0; + break; +#endif + case 'i': + if (stat(optarg, &st) < 0) + { + fprintf(stderr, "Warning: Identity file %s does not exist.\n", + optarg); + break; + } + if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES) + fatal("Too many identity files specified (max %d)", + SSH_MAX_IDENTITY_FILES); + options.identity_files[options.num_identity_files++] = + xstrdup(optarg); + break; + + case 't': + tty_flag = 1; + break; + + case 'v': + case 'V': + debug_flag = 1; + fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n", + SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR); + fprintf(stderr, "Compiled with SSL.\n"); + if (opt == 'V') + exit(0); + break; + + case 'q': + quiet_flag = 1; + break; + + case 'e': + if (optarg[0] == '^' && optarg[2] == 0 && + (unsigned char)optarg[1] >= 64 && (unsigned char)optarg[1] < 128) + options.escape_char = (unsigned char)optarg[1] & 31; + else + if (strlen(optarg) == 1) + options.escape_char = (unsigned char)optarg[0]; + else + if (strcmp(optarg, "none") == 0) + options.escape_char = -2; + else + { + fprintf(stderr, "Bad escape character '%s'.\n", optarg); + exit(1); + } + break; + + case 'c': + options.cipher = cipher_number(optarg); + if (options.cipher == -1) + { + fprintf(stderr, "Unknown cipher type '%s'\n", optarg); + exit(1); + } + break; + + case 'p': + options.port = atoi(optarg); + if (options.port < 1 || options.port > 65535) + { + fprintf(stderr, "Bad port %s.\n", optarg); + exit(1); + } + break; + + case 'l': + options.user = optarg; + break; + + case 'R': + if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf, + &fwd_host_port) != 3) + { + fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); + usage(); + /*NOTREACHED*/ + } + add_remote_forward(&options, fwd_port, buf, fwd_host_port); + break; + + case 'L': + if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf, + &fwd_host_port) != 3) + { + fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); + usage(); + /*NOTREACHED*/ + } + add_local_forward(&options, fwd_port, buf, fwd_host_port); + break; + + case 'C': + options.compression = 1; + break; + + case 'o': + dummy = 1; + process_config_line(&options, host ? host : "", optarg, + "command-line", 0, &dummy); + break; + + default: + usage(); + } + } + + /* Check that we got a host name. */ + if (!host) + usage(); + + /* check if RSA support exists */ + if (rsa_alive() == 0) { + extern char *__progname; + + fprintf(stderr, + "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", + __progname); + exit(1); + } + + /* Initialize the command to execute on remote host. */ + buffer_init(&command); + + /* Save the command to execute on the remote host in a buffer. There is + no limit on the length of the command, except by the maximum packet + size. Also sets the tty flag if there is no command. */ + if (optind == ac) + { + /* No command specified - execute shell on a tty. */ + tty_flag = 1; + } + else + { + /* A command has been specified. Store it into the buffer. */ + for (i = optind; i < ac; i++) + { + if (i > optind) + buffer_append(&command, " ", 1); + buffer_append(&command, av[i], strlen(av[i])); + } + } + + /* Cannot fork to background if no command. */ + if (fork_after_authentication_flag && buffer_len(&command) == 0) + fatal("Cannot fork into background without a command to execute."); + + /* Allocate a tty by default if no command specified. */ + if (buffer_len(&command) == 0) + tty_flag = 1; + + /* Do not allocate a tty if stdin is not a tty. */ + if (!isatty(fileno(stdin))) + { + if (tty_flag) + fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n"); + tty_flag = 0; + } + + /* Get user data. */ + pw = getpwuid(original_real_uid); + if (!pw) + { + fprintf(stderr, "You don't exist, go away!\n"); + exit(1); + } + + /* Take a copy of the returned structure. */ + memset(&pwcopy, 0, sizeof(pwcopy)); + pwcopy.pw_name = xstrdup(pw->pw_name); + pwcopy.pw_passwd = xstrdup(pw->pw_passwd); + pwcopy.pw_uid = pw->pw_uid; + pwcopy.pw_gid = pw->pw_gid; + pwcopy.pw_dir = xstrdup(pw->pw_dir); + pwcopy.pw_shell = xstrdup(pw->pw_shell); + pw = &pwcopy; + + /* Initialize "log" output. Since we are the client all output actually + goes to the terminal. */ + log_init(av[0], 1, debug_flag, quiet_flag, SYSLOG_FACILITY_USER); + + /* Read per-user configuration file. */ + snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE); + read_config_file(buf, host, &options); + + /* Read systemwide configuration file. */ + read_config_file(HOST_CONFIG_FILE, host, &options); + + /* Fill configuration defaults. */ + fill_default_options(&options); + if (options.user == NULL) + options.user = xstrdup(pw->pw_name); + + if (options.hostname != NULL) + host = options.hostname; + + /* Find canonic host name. */ + if (strchr(host, '.') == 0) + { + struct hostent *hp = gethostbyname(host); + if (hp != 0) + { + if (strchr(hp->h_name, '.') != 0) + host = xstrdup(hp->h_name); + else if (hp->h_aliases != 0 + && hp->h_aliases[0] != 0 + && strchr(hp->h_aliases[0], '.') != 0) + host = xstrdup(hp->h_aliases[0]); + } + } + + /* Disable rhosts authentication if not running as root. */ + if (original_effective_uid != 0) + { + options.rhosts_authentication = 0; + options.rhosts_rsa_authentication = 0; + } + + /* If using rsh has been selected, exec it now (without trying anything + else). Note that we must release privileges first. */ + if (options.use_rsh) + { + /* Restore our superuser privileges. This must be done before + permanently setting the uid. */ + restore_uid(); + + /* Switch to the original uid permanently. */ + permanently_set_uid(original_real_uid); + + /* Execute rsh. */ + rsh_connect(host, options.user, &command); + fatal("rsh_connect returned"); + } + + /* Restore our superuser privileges. */ + restore_uid(); + + /* Open a connection to the remote host. This needs root privileges if + rhosts_{rsa_}authentication is true. */ + + if (!options.use_privileged_port) + { + options.rhosts_authentication = 0; + options.rhosts_rsa_authentication = 0; + } + + ok = ssh_connect(host, &hostaddr, options.port, options.connection_attempts, + !options.rhosts_authentication && + !options.rhosts_rsa_authentication, + original_real_uid, options.proxy_command); + + /* If we successfully made the connection, load the host private key in + case we will need it later for combined rsa-rhosts authentication. + This must be done before releasing extra privileges, because the file + is only readable by root. */ + if (ok) + { + host_private_key = RSA_new(); + if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL)) + host_private_key_loaded = 1; + } + + /* Get rid of any extra privileges that we may have. We will no longer need + them. Also, extra privileges could make it very hard to read identity + files and other non-world-readable files from the user's home directory + if it happens to be on a NFS volume where root is mapped to nobody. */ + permanently_set_uid(original_real_uid); + + /* Now that we are back to our own permissions, create ~/.ssh directory + if it doesn\'t already exist. */ + snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR); + if (stat(buf, &st) < 0) + if (mkdir(buf, 0755) < 0) + error("Could not create directory '%.200s'.", buf); + + /* Check if the connection failed, and try "rsh" if appropriate. */ + if (!ok) + { + if (options.port != 0) + log("Secure connection to %.100s on port %d refused%.100s.", + host, options.port, + options.fallback_to_rsh ? "; reverting to insecure method" : ""); + else + log("Secure connection to %.100s refused%.100s.", host, + options.fallback_to_rsh ? "; reverting to insecure method" : ""); + + if (options.fallback_to_rsh) + { + rsh_connect(host, options.user, &command); + fatal("rsh_connect returned"); + } + exit(1); + } + + /* Expand ~ in options.identity_files. */ + for (i = 0; i < options.num_identity_files; i++) + options.identity_files[i] = + tilde_expand_filename(options.identity_files[i], original_real_uid); + + /* Expand ~ in known host file names. */ + options.system_hostfile = tilde_expand_filename(options.system_hostfile, + original_real_uid); + options.user_hostfile = tilde_expand_filename(options.user_hostfile, + original_real_uid); + + /* Log into the remote system. This never returns if the login fails. */ + ssh_login(host_private_key_loaded, host_private_key, + host, &hostaddr, &options, original_real_uid); + + /* We no longer need the host private key. Clear it now. */ + if (host_private_key_loaded) + RSA_free(host_private_key); /* Destroys contents safely */ + + /* Close connection cleanly after attack. */ + cipher_attack_detected = packet_disconnect; + + /* If requested, fork and let ssh continue in the background. */ + if (fork_after_authentication_flag) + { + int ret = fork(); + if (ret == -1) + fatal("fork failed: %.100s", strerror(errno)); + if (ret != 0) + exit(0); + setsid(); + } + + /* Enable compression if requested. */ + if (options.compression) + { + debug("Requesting compression at level %d.", options.compression_level); + + if (options.compression_level < 1 || options.compression_level > 9) + fatal("Compression level must be from 1 (fast) to 9 (slow, best)."); + + /* Send the request. */ + packet_start(SSH_CMSG_REQUEST_COMPRESSION); + packet_put_int(options.compression_level); + packet_send(); + packet_write_wait(); + type = packet_read(&plen); + if (type == SSH_SMSG_SUCCESS) + packet_start_compression(options.compression_level); + else if (type == SSH_SMSG_FAILURE) + log("Warning: Remote host refused compression."); + else + packet_disconnect("Protocol error waiting for compression response."); + } + + /* Allocate a pseudo tty if appropriate. */ + if (tty_flag) + { + debug("Requesting pty."); + + /* Start the packet. */ + packet_start(SSH_CMSG_REQUEST_PTY); + + /* Store TERM in the packet. There is no limit on the length of the + string. */ + cp = getenv("TERM"); + if (!cp) + cp = ""; + packet_put_string(cp, strlen(cp)); + + /* Store window size in the packet. */ + if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) + memset(&ws, 0, sizeof(ws)); + packet_put_int(ws.ws_row); + packet_put_int(ws.ws_col); + packet_put_int(ws.ws_xpixel); + packet_put_int(ws.ws_ypixel); + + /* Store tty modes in the packet. */ + tty_make_modes(fileno(stdin)); + + /* Send the packet, and wait for it to leave. */ + packet_send(); + packet_write_wait(); + + /* Read response from the server. */ + type = packet_read(&plen); + if (type == SSH_SMSG_SUCCESS) + interactive = 1; + else if (type == SSH_SMSG_FAILURE) + log("Warning: Remote host failed or refused to allocate a pseudo tty."); + else + packet_disconnect("Protocol error waiting for pty request response."); + } + + /* Request X11 forwarding if enabled and DISPLAY is set. */ + if (options.forward_x11 && getenv("DISPLAY") != NULL) + { + char line[512], proto[512], data[512]; + FILE *f; + int forwarded = 0, got_data = 0, i; + +#ifdef XAUTH_PATH + /* Try to get Xauthority information for the display. */ + snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null", + XAUTH_PATH, getenv("DISPLAY")); + f = popen(line, "r"); + if (f && fgets(line, sizeof(line), f) && + sscanf(line, "%*s %s %s", proto, data) == 2) + got_data = 1; + if (f) + pclose(f); +#endif /* XAUTH_PATH */ + /* If we didn't get authentication data, just make up some data. The + forwarding code will check the validity of the response anyway, and + substitute this data. The X11 server, however, will ignore this + fake data and use whatever authentication mechanisms it was using + otherwise for the local connection. */ + if (!got_data) + { + u_int32_t rand = 0; + + strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto); + for (i = 0; i < 16; i++) { + if (i % 4 == 0) + rand = arc4random(); + snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff); + rand >>= 8; + } + } + + /* Got local authentication reasonable information. Request forwarding + with authentication spoofing. */ + debug("Requesting X11 forwarding with authentication spoofing."); + x11_request_forwarding_with_spoofing(proto, data); + + /* Read response from the server. */ + type = packet_read(&plen); + if (type == SSH_SMSG_SUCCESS) + { + forwarded = 1; + interactive = 1; + } + else if (type == SSH_SMSG_FAILURE) + log("Warning: Remote host denied X11 forwarding."); + else + packet_disconnect("Protocol error waiting for X11 forwarding"); + } + + /* Tell the packet module whether this is an interactive session. */ + packet_set_interactive(interactive, options.keepalives); + + /* Clear agent forwarding if we don\'t have an agent. */ + authfd = ssh_get_authentication_socket(); + if (authfd < 0) + options.forward_agent = 0; + else + ssh_close_authentication_socket(authfd); + + /* Request authentication agent forwarding if appropriate. */ + if (options.forward_agent) + { + debug("Requesting authentication agent forwarding."); + auth_request_forwarding(); + + /* Read response from the server. */ + type = packet_read(&plen); + packet_integrity_check(plen, 0, type); + if (type != SSH_SMSG_SUCCESS) + log("Warning: Remote host denied authentication agent forwarding."); + } + + /* Initiate local TCP/IP port forwardings. */ + for (i = 0; i < options.num_local_forwards; i++) + { + debug("Connections to local port %d forwarded to remote address %.200s:%d", + options.local_forwards[i].port, options.local_forwards[i].host, + options.local_forwards[i].host_port); + channel_request_local_forwarding(options.local_forwards[i].port, + options.local_forwards[i].host, + options.local_forwards[i].host_port); + } + + /* Initiate remote TCP/IP port forwardings. */ + for (i = 0; i < options.num_remote_forwards; i++) + { + debug("Connections to remote port %d forwarded to local address %.200s:%d", + options.remote_forwards[i].port, options.remote_forwards[i].host, + options.remote_forwards[i].host_port); + channel_request_remote_forwarding(options.remote_forwards[i].port, + options.remote_forwards[i].host, + options.remote_forwards[i].host_port); + } + + /* If a command was specified on the command line, execute the command now. + Otherwise request the server to start a shell. */ + if (buffer_len(&command) > 0) + { + int len = buffer_len(&command); + if (len > 900) + len = 900; + debug("Sending command: %.*s", len, buffer_ptr(&command)); + packet_start(SSH_CMSG_EXEC_CMD); + packet_put_string(buffer_ptr(&command), buffer_len(&command)); + packet_send(); + packet_write_wait(); + } + else + { + debug("Requesting shell."); + packet_start(SSH_CMSG_EXEC_SHELL); + packet_send(); + packet_write_wait(); + } + + /* Enter the interactive session. */ + exit_status = client_loop(tty_flag, tty_flag ? options.escape_char : -1); + + /* Close the connection to the remote host. */ + packet_close(); + + /* Exit with the status returned by the program on the remote side. */ + exit(exit_status); +} diff --git a/ssh.h b/ssh.h new file mode 100644 index 00000000..4284bc91 --- /dev/null +++ b/ssh.h @@ -0,0 +1,589 @@ +/* + +ssh.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Fri Mar 17 17:09:37 1995 ylo + +Generic header file for ssh. + +*/ + +/* RCSID("$Id$"); */ + +#ifndef SSH_H +#define SSH_H + +#include "rsa.h" +#include "cipher.h" + +/* The default cipher used if IDEA is not supported by the remote host. + It is recommended that this be one of the mandatory ciphers (DES, 3DES), + though that is not required. */ +#define SSH_FALLBACK_CIPHER SSH_CIPHER_3DES + +/* Cipher used for encrypting authentication files. */ +#define SSH_AUTHFILE_CIPHER SSH_CIPHER_3DES + +/* Default port number. */ +#define SSH_DEFAULT_PORT 22 + +/* Maximum number of TCP/IP ports forwarded per direction. */ +#define SSH_MAX_FORWARDS_PER_DIRECTION 100 + +/* Maximum number of RSA authentication identity files that can be specified + in configuration files or on the command line. */ +#define SSH_MAX_IDENTITY_FILES 100 + +/* Major protocol version. Different version indicates major incompatiblity + that prevents communication. */ +#define PROTOCOL_MAJOR 1 + +/* Minor protocol version. Different version indicates minor incompatibility + that does not prevent interoperation. */ +#define PROTOCOL_MINOR 5 + +/* Name for the service. The port named by this service overrides the default + port if present. */ +#define SSH_SERVICE_NAME "ssh" + +#ifndef ETCDIR +#define ETCDIR "/etc" +#endif /* ETCDIR */ + +#define PIDDIR "/var/run" + +/* System-wide file containing host keys of known hosts. This file should be + world-readable. */ +#define SSH_SYSTEM_HOSTFILE ETCDIR "/ssh_known_hosts" + +/* HOST_KEY_FILE /etc/ssh_host_key, + SERVER_CONFIG_FILE /etc/sshd_config, +and HOST_CONFIG_FILE /etc/ssh_config +are all defined in Makefile.in. Of these, ssh_host_key should be readable +only by root, whereas ssh_config should be world-readable. */ + +#define HOST_KEY_FILE ETCDIR "/ssh_host_key" +#define SERVER_CONFIG_FILE ETCDIR "/sshd_config" +#define HOST_CONFIG_FILE ETCDIR "/ssh_config" + +#define SSH_PROGRAM "/usr/bin/ssh" + +/* The process id of the daemon listening for connections is saved + here to make it easier to kill the correct daemon when necessary. */ +#define SSH_DAEMON_PID_FILE PIDDIR "/sshd.pid" + +/* The directory in user\'s home directory in which the files reside. + The directory should be world-readable (though not all files are). */ +#define SSH_USER_DIR ".ssh" + +/* Per-user file containing host keys of known hosts. This file need + not be readable by anyone except the user him/herself, though this does + not contain anything particularly secret. */ +#define SSH_USER_HOSTFILE "~/.ssh/known_hosts" + +/* Name of the default file containing client-side authentication key. + This file should only be readable by the user him/herself. */ +#define SSH_CLIENT_IDENTITY ".ssh/identity" + +/* Configuration file in user\'s home directory. This file need not be + readable by anyone but the user him/herself, but does not contain + anything particularly secret. If the user\'s home directory resides + on an NFS volume where root is mapped to nobody, this may need to be + world-readable. */ +#define SSH_USER_CONFFILE ".ssh/config" + +/* File containing a list of those rsa keys that permit logging in as + this user. This file need not be + readable by anyone but the user him/herself, but does not contain + anything particularly secret. If the user\'s home directory resides + on an NFS volume where root is mapped to nobody, this may need to be + world-readable. (This file is read by the daemon which is running as + root.) */ +#define SSH_USER_PERMITTED_KEYS ".ssh/authorized_keys" + +/* Per-user and system-wide ssh "rc" files. These files are executed with + /bin/sh before starting the shell or command if they exist. They + will be passed "proto cookie" as arguments if X11 forwarding with + spoofing is in use. xauth will be run if neither of these exists. */ +#define SSH_USER_RC ".ssh/rc" +#define SSH_SYSTEM_RC ETCDIR "/sshrc" + +/* Ssh-only version of /etc/hosts.equiv. */ +#define SSH_HOSTS_EQUIV ETCDIR "/shosts.equiv" + +/* Additionally, the daemon may use ~/.rhosts and /etc/hosts.equiv if + rhosts authentication is enabled. */ + +/* Name of the environment variable containing the pathname of the + authentication socket. */ +#define SSH_AUTHSOCKET_ENV_NAME "SSH_AUTH_SOCK" + +/* Force host key length and server key length to differ by at least this + many bits. This is to make double encryption with rsaref work. */ +#define SSH_KEY_BITS_RESERVED 128 + +/* Length of the session key in bytes. (Specified as 256 bits in the + protocol.) */ +#define SSH_SESSION_KEY_LENGTH 32 + +/* Name of Kerberos service for SSH to use. */ +#define KRB4_SERVICE_NAME "rcmd" + +/* Authentication methods. New types can be added, but old types should not + be removed for compatibility. The maximum allowed value is 31. */ +#define SSH_AUTH_RHOSTS 1 +#define SSH_AUTH_RSA 2 +#define SSH_AUTH_PASSWORD 3 +#define SSH_AUTH_RHOSTS_RSA 4 + /* 5 is TIS */ +#define SSH_AUTH_KERBEROS 6 +#define SSH_PASS_KERBEROS_TGT 7 + /* 8 to 15 are reserved */ +#define SSH_PASS_AFS_TOKEN 21 + +/* Protocol flags. These are bit masks. */ +#define SSH_PROTOFLAG_SCREEN_NUMBER 1 /* X11 forwarding includes screen */ +#define SSH_PROTOFLAG_HOST_IN_FWD_OPEN 2 /* forwarding opens contain host */ + +/* Definition of message types. New values can be added, but old values + should not be removed or without careful consideration of the consequences + for compatibility. The maximum value is 254; value 255 is reserved + for future extension. */ +/* Message name */ /* msg code */ /* arguments */ +#define SSH_MSG_NONE 0 /* no message */ +#define SSH_MSG_DISCONNECT 1 /* cause (string) */ +#define SSH_SMSG_PUBLIC_KEY 2 /* ck,msk,srvk,hostk */ +#define SSH_CMSG_SESSION_KEY 3 /* key (BIGNUM) */ +#define SSH_CMSG_USER 4 /* user (string) */ +#define SSH_CMSG_AUTH_RHOSTS 5 /* user (string) */ +#define SSH_CMSG_AUTH_RSA 6 /* modulus (BIGNUM) */ +#define SSH_SMSG_AUTH_RSA_CHALLENGE 7 /* int (BIGNUM) */ +#define SSH_CMSG_AUTH_RSA_RESPONSE 8 /* int (BIGNUM) */ +#define SSH_CMSG_AUTH_PASSWORD 9 /* pass (string) */ +#define SSH_CMSG_REQUEST_PTY 10 /* TERM, tty modes */ +#define SSH_CMSG_WINDOW_SIZE 11 /* row,col,xpix,ypix */ +#define SSH_CMSG_EXEC_SHELL 12 /* */ +#define SSH_CMSG_EXEC_CMD 13 /* cmd (string) */ +#define SSH_SMSG_SUCCESS 14 /* */ +#define SSH_SMSG_FAILURE 15 /* */ +#define SSH_CMSG_STDIN_DATA 16 /* data (string) */ +#define SSH_SMSG_STDOUT_DATA 17 /* data (string) */ +#define SSH_SMSG_STDERR_DATA 18 /* data (string) */ +#define SSH_CMSG_EOF 19 /* */ +#define SSH_SMSG_EXITSTATUS 20 /* status (int) */ +#define SSH_MSG_CHANNEL_OPEN_CONFIRMATION 21 /* channel (int) */ +#define SSH_MSG_CHANNEL_OPEN_FAILURE 22 /* channel (int) */ +#define SSH_MSG_CHANNEL_DATA 23 /* ch,data (int,str) */ +#define SSH_MSG_CHANNEL_CLOSE 24 /* channel (int) */ +#define SSH_MSG_CHANNEL_CLOSE_CONFIRMATION 25 /* channel (int) */ +/* SSH_CMSG_X11_REQUEST_FORWARDING 26 OBSOLETE */ +#define SSH_SMSG_X11_OPEN 27 /* channel (int) */ +#define SSH_CMSG_PORT_FORWARD_REQUEST 28 /* p,host,hp (i,s,i) */ +#define SSH_MSG_PORT_OPEN 29 /* ch,h,p (i,s,i) */ +#define SSH_CMSG_AGENT_REQUEST_FORWARDING 30 /* */ +#define SSH_SMSG_AGENT_OPEN 31 /* port (int) */ +#define SSH_MSG_IGNORE 32 /* string */ +#define SSH_CMSG_EXIT_CONFIRMATION 33 /* */ +#define SSH_CMSG_X11_REQUEST_FORWARDING 34 /* proto,data (s,s) */ +#define SSH_CMSG_AUTH_RHOSTS_RSA 35 /* user,mod (s,mpi) */ +#define SSH_MSG_DEBUG 36 /* string */ +#define SSH_CMSG_REQUEST_COMPRESSION 37 /* level 1-9 (int) */ +#define SSH_CMSG_MAX_PACKET_SIZE 38 /* size 4k-1024k (int) */ +#define SSH_CMSG_AUTH_TIS 39 /* this is proto-1.5, but we ignore TIS */ +#define SSH_SMSG_AUTH_TIS_CHALLENGE 40 +#define SSH_CMSG_AUTH_TIS_RESPONSE 41 + +#define SSH_CMSG_AUTH_KERBEROS 42 /* (KTEXT) */ +#define SSH_SMSG_AUTH_KERBEROS_RESPONSE 43 /* (KTEXT) */ +#define SSH_CMSG_HAVE_KERBEROS_TGT 44 /* credentials (s) */ +#define SSH_CMSG_HAVE_AFS_TOKEN 65 /* token (s) */ + + +/* Includes that need definitions above. */ + +#include "readconf.h" + +/*------------ definitions for login.c -------------*/ + +/* Returns the time when the user last logged in. Returns 0 if the + information is not available. This must be called before record_login. + The host from which the user logged in is stored in buf. */ +unsigned long get_last_login_time(uid_t uid, const char *logname, + char *buf, unsigned int bufsize); + +/* Records that the user has logged in. This does many things normally + done by login(1). */ +void record_login(int pid, const char *ttyname, const char *user, uid_t uid, + const char *host, struct sockaddr_in *addr); + +/* Records that the user has logged out. This does many thigs normally + done by login(1) or init. */ +void record_logout(int pid, const char *ttyname); + +/*------------ definitions for sshconnect.c ----------*/ + +/* Opens a TCP/IP connection to the remote server on the given host. If + port is 0, the default port will be used. If anonymous is zero, + a privileged port will be allocated to make the connection. + This requires super-user privileges if anonymous is false. + Connection_attempts specifies the maximum number of tries, one per + second. This returns true on success, and zero on failure. If the + connection is successful, this calls packet_set_connection for the + connection. */ +int ssh_connect(const char *host, struct sockaddr_in *hostaddr, + int port, int connection_attempts, + int anonymous, uid_t original_real_uid, + const char *proxy_command); + +/* Starts a dialog with the server, and authenticates the current user on the + server. This does not need any extra privileges. The basic connection + to the server must already have been established before this is called. + If login fails, this function prints an error and never returns. + This initializes the random state, and leaves it initialized (it will also + have references from the packet module). */ +void ssh_login(int host_key_valid, RSA *host_key, const char *host, + struct sockaddr_in *hostaddr, Options *options, + uid_t original_real_uid); + +/*------------ Definitions for various authentication methods. -------*/ + +/* Tries to authenticate the user using the .rhosts file. Returns true if + authentication succeeds. If ignore_rhosts is non-zero, this will not + consider .rhosts and .shosts (/etc/hosts.equiv will still be used). + If strict_modes is true, checks ownership and modes of .rhosts/.shosts. */ +int auth_rhosts(struct passwd *pw, const char *client_user, + int ignore_rhosts, int strict_modes); + +/* Tries to authenticate the user using the .rhosts file and the host using + its host key. Returns true if authentication succeeds. */ +int auth_rhosts_rsa(struct passwd *pw, const char *client_user, + unsigned int bits, BIGNUM *client_host_key_e, + BIGNUM *client_host_key_n, int ignore_rhosts, + int strict_modes); + +/* Tries to authenticate the user using password. Returns true if + authentication succeeds. */ +int auth_password(struct passwd *pw, const char *password); + +/* Performs the RSA authentication dialog with the client. This returns + 0 if the client could not be authenticated, and 1 if authentication was + successful. This may exit if there is a serious protocol violation. */ +int auth_rsa(struct passwd *pw, BIGNUM *client_n, int strict_modes); + +/* Parses an RSA key (number of bits, e, n) from a string. Moves the pointer + over the key. Skips any whitespace at the beginning and at end. */ +int auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM *e, BIGNUM *n); + +/* Returns the name of the machine at the other end of the socket. The + returned string should be freed by the caller. */ +char *get_remote_hostname(int socket); + +/* Return the canonical name of the host in the other side of the current + connection (as returned by packet_get_connection). The host name is + cached, so it is efficient to call this several times. */ +const char *get_canonical_hostname(void); + +/* Returns the remote IP address as an ascii string. The value need not be + freed by the caller. */ +const char *get_remote_ipaddr(void); + +/* Returns the port number of the peer of the socket. */ +int get_peer_port(int sock); + +/* Returns the port number of the remote host. */ +int get_remote_port(void); + +/* Tries to match the host name (which must be in all lowercase) against the + comma-separated sequence of subpatterns (each possibly preceded by ! to + indicate negation). Returns true if there is a positive match; zero + otherwise. */ +int match_hostname(const char *host, const char *pattern, unsigned int len); + +/* Checks whether the given host is already in the list of our known hosts. + Returns HOST_OK if the host is known and has the specified key, + HOST_NEW if the host is not known, and HOST_CHANGED if the host is known + but used to have a different host key. The host must be in all lowercase. */ +typedef enum { HOST_OK, HOST_NEW, HOST_CHANGED } HostStatus; +HostStatus check_host_in_hostfile(const char *filename, + const char *host, unsigned int bits, + BIGNUM *e, BIGNUM *n, + BIGNUM *ke, BIGNUM *kn); + +/* Appends an entry to the host file. Returns false if the entry + could not be appended. */ +int add_host_to_hostfile(const char *filename, const char *host, + unsigned int bits, BIGNUM *e, BIGNUM *n); + +/* Performs the RSA authentication challenge-response dialog with the client, + and returns true (non-zero) if the client gave the correct answer to + our challenge; returns zero if the client gives a wrong answer. */ +int auth_rsa_challenge_dialog(unsigned int bits, BIGNUM *e, BIGNUM *n); + +/* Reads a passphrase from /dev/tty with echo turned off. Returns the + passphrase (allocated with xmalloc). Exits if EOF is encountered. + If from_stdin is true, the passphrase will be read from stdin instead. */ +char *read_passphrase(const char *prompt, int from_stdin); + +/* Saves the authentication (private) key in a file, encrypting it with + passphrase. The identification of the file (lowest 64 bits of n) + will precede the key to provide identification of the key without + needing a passphrase. */ +int save_private_key(const char *filename, const char *passphrase, + RSA *private_key, const char *comment); + +/* Loads the public part of the key file (public key and comment). + Returns 0 if an error occurred; zero if the public key was successfully + read. The comment of the key is returned in comment_return if it is + non-NULL; the caller must free the value with xfree. */ +int load_public_key(const char *filename, RSA *pub, + char **comment_return); + +/* Loads the private key from the file. Returns 0 if an error is encountered + (file does not exist or is not readable, or passphrase is bad). + This initializes the private key. The comment of the key is returned + in comment_return if it is non-NULL; the caller must free the value + with xfree. */ +int load_private_key(const char *filename, const char *passphrase, + RSA *private_key, char **comment_return); + +/*------------ Definitions for logging. -----------------------*/ + +/* Supported syslog facilities. */ +typedef enum +{ + SYSLOG_FACILITY_DAEMON, + SYSLOG_FACILITY_USER, + SYSLOG_FACILITY_AUTH, + SYSLOG_FACILITY_LOCAL0, + SYSLOG_FACILITY_LOCAL1, + SYSLOG_FACILITY_LOCAL2, + SYSLOG_FACILITY_LOCAL3, + SYSLOG_FACILITY_LOCAL4, + SYSLOG_FACILITY_LOCAL5, + SYSLOG_FACILITY_LOCAL6, + SYSLOG_FACILITY_LOCAL7 +} SyslogFacility; + +/* Initializes logging. If debug is non-zero, debug() will output something. + If quiet is non-zero, none of these will log send anything to syslog + (but maybe to stderr). */ +void log_init(char *av0, int on_stderr, int debug, int quiet, + SyslogFacility facility); + +/* Outputs a message to syslog or stderr, depending on the implementation. + The format must guarantee that the final message does not exceed 1024 + characters. The message should not contain newline. */ +void log(const char *fmt, ...); + +/* Outputs a message to syslog or stderr, depending on the implementation. + The format must guarantee that the final message does not exceed 1024 + characters. The message should not contain newline. */ +void debug(const char *fmt, ...); + +/* Outputs a message to syslog or stderr, depending on the implementation. + The format must guarantee that the final message does not exceed 1024 + characters. The message should not contain newline. */ +void error(const char *fmt, ...); + +/* Outputs a message to syslog or stderr, depending on the implementation. + The format must guarantee that the final message does not exceed 1024 + characters. The message should not contain newline. + This call never returns. */ +void fatal(const char *fmt, ...); + +/* Registers a cleanup function to be called by fatal() before exiting. + It is permissible to call fatal_remove_cleanup for the function itself + from the function. */ +void fatal_add_cleanup(void (*proc)(void *context), void *context); + +/* Removes a cleanup frunction to be called at fatal(). */ +void fatal_remove_cleanup(void (*proc)(void *context), void *context); + +/*---------------- definitions for channels ------------------*/ + +/* Sets specific protocol options. */ +void channel_set_options(int hostname_in_open); + +/* Allocate a new channel object and set its type and socket. Remote_name + must have been allocated with xmalloc; this will free it when the channel + is freed. */ +int channel_allocate(int type, int sock, char *remote_name); + +/* Free the channel and close its socket. */ +void channel_free(int channel); + +/* Add any bits relevant to channels in select bitmasks. */ +void channel_prepare_select(fd_set *readset, fd_set *writeset); + +/* After select, perform any appropriate operations for channels which + have events pending. */ +void channel_after_select(fd_set *readset, fd_set *writeset); + +/* If there is data to send to the connection, send some of it now. */ +void channel_output_poll(void); + +/* This is called when a packet of type CHANNEL_DATA has just been received. + The message type has already been consumed, but channel number and data + is still there. */ +void channel_input_data(int payload_len); + +/* Returns true if no channel has too much buffered data. */ +int channel_not_very_much_buffered_data(void); + +/* This is called after receiving CHANNEL_CLOSE. */ +void channel_input_close(void); + +/* This is called after receiving CHANNEL_CLOSE_CONFIRMATION. */ +void channel_input_close_confirmation(void); + +/* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */ +void channel_input_open_confirmation(void); + +/* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */ +void channel_input_open_failure(void); + +/* This closes any sockets that are listening for connections; this removes + any unix domain sockets. */ +void channel_stop_listening(void); + +/* Closes the sockets of all channels. This is used to close extra file + descriptors after a fork. */ +void channel_close_all(void); + +/* Returns the maximum file descriptor number used by the channels. */ +int channel_max_fd(void); + +/* Returns true if there is still an open channel over the connection. */ +int channel_still_open(void); + +/* Returns a string containing a list of all open channels. The list is + suitable for displaying to the user. It uses crlf instead of newlines. + The caller should free the string with xfree. */ +char *channel_open_message(void); + +/* Initiate forwarding of connections to local port "port" through the secure + channel to host:port from remote side. This never returns if there + was an error. */ +void channel_request_local_forwarding(int port, const char *host, + int remote_port); + +/* Initiate forwarding of connections to port "port" on remote host through + the secure channel to host:port from local side. This never returns + if there was an error. This registers that open requests for that + port are permitted. */ +void channel_request_remote_forwarding(int port, const char *host, + int remote_port); + +/* Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually + called by the server, because the user could connect to any port anyway, + and the server has no way to know but to trust the client anyway. */ +void channel_permit_all_opens(void); + +/* This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates + listening for the port, and sends back a success reply (or disconnect + message if there was an error). This never returns if there was an + error. */ +void channel_input_port_forward_request(int is_root); + +/* This is called after receiving PORT_OPEN message. This attempts to connect + to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION or + CHANNEL_OPEN_FAILURE. */ +void channel_input_port_open(int payload_len); + +/* Creates a port for X11 connections, and starts listening for it. + Returns the display name, or NULL if an error was encountered. */ +char *x11_create_display(int screen); + +/* Creates an internet domain socket for listening for X11 connections. + Returns a suitable value for the DISPLAY variable, or NULL if an error + occurs. */ +char *x11_create_display_inet(int screen); + +/* This is called when SSH_SMSG_X11_OPEN is received. The packet contains + the remote channel number. We should do whatever we want, and respond + with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. */ +void x11_input_open(int payload_len); + +/* Requests forwarding of X11 connections. This should be called on the + client only. */ +void x11_request_forwarding(void); + +/* Requests forwarding for X11 connections, with authentication spoofing. + This should be called in the client only. */ +void x11_request_forwarding_with_spoofing(const char *proto, const char *data); + +/* Local Xauthority file (server only). */ +extern char *xauthfile; + +/* Sends a message to the server to request authentication fd forwarding. */ +void auth_request_forwarding(void); + +/* Returns the name of the forwarded authentication socket. Returns NULL + if there is no forwarded authentication socket. The returned value points + to a static buffer. */ +char *auth_get_socket_name(void); + +/* This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. + This starts forwarding authentication requests. */ +void auth_input_request_forwarding(struct passwd *pw); + +/* This is called to process an SSH_SMSG_AGENT_OPEN message. */ +void auth_input_open_request(void); + +/* Returns true if the given string matches the pattern (which may contain + ? and * as wildcards), and zero if it does not match. */ +int match_pattern(const char *s, const char *pattern); + +/* Expands tildes in the file name. Returns data allocated by xmalloc. + Warning: this calls getpw*. */ +char *tilde_expand_filename(const char *filename, uid_t my_uid); + +/* Performs the interactive session. This handles data transmission between + the client and the program. Note that the notion of stdin, stdout, and + stderr in this function is sort of reversed: this function writes to + stdin (of the child program), and reads from stdout and stderr (of the + child program). */ +void server_loop(int pid, int fdin, int fdout, int fderr); + +/* Client side main loop for the interactive session. */ +int client_loop(int have_pty, int escape_char); + +/* Linked list of custom environment strings (see auth-rsa.c). */ +struct envstring { + struct envstring *next; + char *s; +}; + +#ifdef KRB4 +#include + +/* Performs Kerberos v4 mutual authentication with the client. This returns + 0 if the client could not be authenticated, and 1 if authentication was + successful. This may exit if there is a serious protocol violation. */ +int auth_krb4(const char *server_user, KTEXT auth, char **client); +int ssh_tf_init(uid_t uid); + +#ifdef AFS +#include + +/* Accept passed Kerberos v4 ticket-granting ticket and AFS tokens. */ +int auth_kerberos_tgt(struct passwd *pw, const char *string); +int auth_afs_token(char *server_user, uid_t uid, const char *string); + +int creds_to_radix(CREDENTIALS *creds, unsigned char *buf); +int radix_to_creds(const char *buf, CREDENTIALS *creds); +#endif /* AFS */ + +#endif /* KRB4 */ + +#ifdef SKEY +#include +char *skey_fake_keyinfo(char *username); +#endif /* SKEY */ + +#endif /* SSH_H */ diff --git a/ssh.pam b/ssh.pam new file mode 100644 index 00000000..2a7d1fbd --- /dev/null +++ b/ssh.pam @@ -0,0 +1,7 @@ +#%PAM-1.0 +auth required /lib/security/pam_pwdb.so shadow +auth required /lib/security/pam_nologin.so +account required /lib/security/pam_pwdb.so +password required /lib/security/pam_cracklib.so +password required /lib/security/pam_pwdb.so shadow nullok use_authtok +session required /lib/security/pam_pwdb.so diff --git a/ssh_config b/ssh_config new file mode 100644 index 00000000..9fb064de --- /dev/null +++ b/ssh_config @@ -0,0 +1,30 @@ +# This is ssh client systemwide configuration file. This file provides +# defaults for users, and the values can be changed in per-user configuration +# files or on the command line. + +# Configuration data is parsed as follows: +# 1. command line options +# 2. user-specific file +# 3. system-wide file +# Any configuration value is only changed the first time it is set. +# Thus, host-specific definitions should be at the beginning of the +# configuration file, and defaults at the end. + +# Site-wide defaults for various options + +# Host * +# ForwardAgent yes +# ForwardX11 yes +# RhostsAuthentication yes +# RhostsRSAAuthentication yes +# RSAAuthentication yes +# PasswordAuthentication yes +# FallBackToRsh yes +# UseRsh no +# BatchMode no +# CheckHostIP yes +# StrictHostKeyChecking no +# IdentityFile ~/.ssh/identity +# Port 22 +# Cipher blowfish +# EscapeChar ~ diff --git a/sshconnect.c b/sshconnect.c new file mode 100644 index 00000000..e87dc646 --- /dev/null +++ b/sshconnect.c @@ -0,0 +1,1495 @@ +/* + +sshconnect.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Mar 18 22:15:47 1995 ylo + +Code to connect to a remote host, and to perform the client side of the +login (authentication) dialog. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include +#include "xmalloc.h" +#include "rsa.h" +#include "ssh.h" +#include "packet.h" +#include "authfd.h" +#include "cipher.h" +#include "mpaux.h" +#include "uidswap.h" +#include "compat.h" + +#include + +/* Session id for the current session. */ +unsigned char session_id[16]; + +/* Connect to the given ssh server using a proxy command. */ + +int +ssh_proxy_connect(const char *host, int port, uid_t original_real_uid, + const char *proxy_command) +{ + Buffer command; + const char *cp; + char *command_string; + int pin[2], pout[2]; + int pid; + char portstring[100]; + + /* Convert the port number into a string. */ + snprintf(portstring, sizeof portstring, "%d", port); + + /* Build the final command string in the buffer by making the appropriate + substitutions to the given proxy command. */ + buffer_init(&command); + for (cp = proxy_command; *cp; cp++) + { + if (cp[0] == '%' && cp[1] == '%') + { + buffer_append(&command, "%", 1); + cp++; + continue; + } + if (cp[0] == '%' && cp[1] == 'h') + { + buffer_append(&command, host, strlen(host)); + cp++; + continue; + } + if (cp[0] == '%' && cp[1] == 'p') + { + buffer_append(&command, portstring, strlen(portstring)); + cp++; + continue; + } + buffer_append(&command, cp, 1); + } + buffer_append(&command, "\0", 1); + + /* Get the final command string. */ + command_string = buffer_ptr(&command); + + /* Create pipes for communicating with the proxy. */ + if (pipe(pin) < 0 || pipe(pout) < 0) + fatal("Could not create pipes to communicate with the proxy: %.100s", + strerror(errno)); + + debug("Executing proxy command: %.500s", command_string); + + /* Fork and execute the proxy command. */ + if ((pid = fork()) == 0) + { + char *argv[10]; + + /* Child. Permanently give up superuser privileges. */ + permanently_set_uid(original_real_uid); + + /* Redirect stdin and stdout. */ + close(pin[1]); + if (pin[0] != 0) + { + if (dup2(pin[0], 0) < 0) + perror("dup2 stdin"); + close(pin[0]); + } + close(pout[0]); + if (dup2(pout[1], 1) < 0) + perror("dup2 stdout"); + close(pout[1]); /* Cannot be 1 because pin allocated two descriptors. */ + + /* Stderr is left as it is so that error messages get printed on + the user's terminal. */ + argv[0] = "/bin/sh"; + argv[1] = "-c"; + argv[2] = command_string; + argv[3] = NULL; + + /* Execute the proxy command. Note that we gave up any extra + privileges above. */ + execv("/bin/sh", argv); + perror("/bin/sh"); + exit(1); + } + /* Parent. */ + if (pid < 0) + fatal("fork failed: %.100s", strerror(errno)); + + /* Close child side of the descriptors. */ + close(pin[0]); + close(pout[1]); + + /* Free the command name. */ + buffer_free(&command); + + /* Set the connection file descriptors. */ + packet_set_connection(pout[0], pin[1]); + + return 1; +} + +/* Creates a (possibly privileged) socket for use as the ssh connection. */ + +int ssh_create_socket(uid_t original_real_uid, int privileged) +{ + int sock; + + /* If we are running as root and want to connect to a privileged port, + bind our own socket to a privileged port. */ + if (privileged) + { + int p = IPPORT_RESERVED - 1; + + sock = rresvport(&p); + if (sock < 0) + fatal("rresvport: %.100s", strerror(errno)); + debug("Allocated local port %d.", p); + } + else + { + /* Just create an ordinary socket on arbitrary port. We use the + user's uid to create the socket. */ + temporarily_use_uid(original_real_uid); + sock = socket(AF_INET, SOCK_STREAM, 0); + if (sock < 0) + fatal("socket: %.100s", strerror(errno)); + restore_uid(); + } + return sock; +} + +/* Opens a TCP/IP connection to the remote server on the given host. If + port is 0, the default port will be used. If anonymous is zero, + a privileged port will be allocated to make the connection. + This requires super-user privileges if anonymous is false. + Connection_attempts specifies the maximum number of tries (one per + second). If proxy_command is non-NULL, it specifies the command (with %h + and %p substituted for host and port, respectively) to use to contact + the daemon. */ + +int ssh_connect(const char *host, struct sockaddr_in *hostaddr, + int port, int connection_attempts, + int anonymous, uid_t original_real_uid, + const char *proxy_command) +{ + int sock = -1, attempt, i; + int on = 1; + struct servent *sp; + struct hostent *hp; + struct linger linger; + + debug("ssh_connect: getuid %d geteuid %d anon %d", + (int)getuid(), (int)geteuid(), anonymous); + + /* Get default port if port has not been set. */ + if (port == 0) + { + sp = getservbyname(SSH_SERVICE_NAME, "tcp"); + if (sp) + port = ntohs(sp->s_port); + else + port = SSH_DEFAULT_PORT; + } + + /* If a proxy command is given, connect using it. */ + if (proxy_command != NULL) + return ssh_proxy_connect(host, port, original_real_uid, proxy_command); + + /* No proxy command. */ + + /* No host lookup made yet. */ + hp = NULL; + + /* Try to connect several times. On some machines, the first time will + sometimes fail. In general socket code appears to behave quite + magically on many machines. */ + for (attempt = 0; attempt < connection_attempts; attempt++) + { + if (attempt > 0) + debug("Trying again..."); + + /* Try to parse the host name as a numeric inet address. */ + memset(hostaddr, 0, sizeof(hostaddr)); + hostaddr->sin_family = AF_INET; + hostaddr->sin_port = htons(port); + hostaddr->sin_addr.s_addr = inet_addr(host); + if ((hostaddr->sin_addr.s_addr & 0xffffffff) != 0xffffffff) + { + /* Valid numeric IP address */ + debug("Connecting to %.100s port %d.", + inet_ntoa(hostaddr->sin_addr), port); + + /* Create a socket. */ + sock = ssh_create_socket(original_real_uid, + !anonymous && geteuid() == 0 && + port < IPPORT_RESERVED); + + /* Connect to the host. We use the user's uid in the hope that + it will help with the problems of tcp_wrappers showing the + remote uid as root. */ + temporarily_use_uid(original_real_uid); + if (connect(sock, (struct sockaddr *)hostaddr, sizeof(*hostaddr)) + >= 0) + { + /* Successful connect. */ + restore_uid(); + break; + } + debug("connect: %.100s", strerror(errno)); + restore_uid(); + + /* Destroy the failed socket. */ + shutdown(sock, SHUT_RDWR); + close(sock); + } + else + { + /* Not a valid numeric inet address. */ + /* Map host name to an address. */ + if (!hp) + hp = gethostbyname(host); + if (!hp) + fatal("Bad host name: %.100s", host); + if (!hp->h_addr_list[0]) + fatal("Host does not have an IP address: %.100s", host); + + /* Loop through addresses for this host, and try each one in + sequence until the connection succeeds. */ + for (i = 0; hp->h_addr_list[i]; i++) + { + /* Set the address to connect to. */ + hostaddr->sin_family = hp->h_addrtype; + memcpy(&hostaddr->sin_addr, hp->h_addr_list[i], + sizeof(hostaddr->sin_addr)); + + debug("Connecting to %.200s [%.100s] port %d.", + host, inet_ntoa(hostaddr->sin_addr), port); + + /* Create a socket for connecting. */ + sock = ssh_create_socket(original_real_uid, + !anonymous && geteuid() == 0 && + port < IPPORT_RESERVED); + + /* Connect to the host. We use the user's uid in the hope that + it will help with tcp_wrappers showing the remote uid as + root. */ + temporarily_use_uid(original_real_uid); + if (connect(sock, (struct sockaddr *)hostaddr, + sizeof(*hostaddr)) >= 0) + { + /* Successful connection. */ + restore_uid(); + break; + } + debug("connect: %.100s", strerror(errno)); + restore_uid(); + + /* Close the failed socket; there appear to be some problems + when reusing a socket for which connect() has already + returned an error. */ + shutdown(sock, SHUT_RDWR); + close(sock); + } + if (hp->h_addr_list[i]) + break; /* Successful connection. */ + } + + /* Sleep a moment before retrying. */ + sleep(1); + } + /* Return failure if we didn't get a successful connection. */ + if (attempt >= connection_attempts) + return 0; + + debug("Connection established."); + + /* Set socket options. We would like the socket to disappear as soon as + it has been closed for whatever reason. */ + /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ + setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (void *)&on, sizeof(on)); + linger.l_onoff = 1; + linger.l_linger = 5; + setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); + + /* Set the connection. */ + packet_set_connection(sock, sock); + + return 1; +} + +/* Checks if the user has an authentication agent, and if so, tries to + authenticate using the agent. */ + +int +try_agent_authentication() +{ + int status, type, bits; + char *comment; + AuthenticationConnection *auth; + unsigned char response[16]; + unsigned int i; + BIGNUM *e, *n, *challenge; + + /* Get connection to the agent. */ + auth = ssh_get_authentication_connection(); + if (!auth) + return 0; + + e = BN_new(); + n = BN_new(); + challenge = BN_new(); + + /* Loop through identities served by the agent. */ + for (status = ssh_get_first_identity(auth, &bits, e, n, &comment); + status; + status = ssh_get_next_identity(auth, &bits, e, n, &comment)) + { + int plen, clen; + + /* Try this identity. */ + debug("Trying RSA authentication via agent with '%.100s'", comment); + xfree(comment); + + /* Tell the server that we are willing to authenticate using this key. */ + packet_start(SSH_CMSG_AUTH_RSA); + packet_put_bignum(n); + packet_send(); + packet_write_wait(); + + /* Wait for server's response. */ + type = packet_read(&plen); + + /* The server sends failure if it doesn\'t like our key or does not + support RSA authentication. */ + if (type == SSH_SMSG_FAILURE) + { + debug("Server refused our key."); + continue; + } + + /* Otherwise it should have sent a challenge. */ + if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) + packet_disconnect("Protocol error during RSA authentication: %d", + type); + + packet_get_bignum(challenge, &clen); + + packet_integrity_check(plen, clen, type); + + debug("Received RSA challenge from server."); + + /* Ask the agent to decrypt the challenge. */ + if (!ssh_decrypt_challenge(auth, bits, e, n, challenge, + session_id, 1, response)) + { + /* The agent failed to authenticate this identifier although it + advertised it supports this. Just return a wrong value. */ + log("Authentication agent failed to decrypt challenge."); + memset(response, 0, sizeof(response)); + } + + debug("Sending response to RSA challenge."); + + /* Send the decrypted challenge back to the server. */ + packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); + for (i = 0; i < 16; i++) + packet_put_char(response[i]); + packet_send(); + packet_write_wait(); + + /* Wait for response from the server. */ + type = packet_read(&plen); + + /* The server returns success if it accepted the authentication. */ + if (type == SSH_SMSG_SUCCESS) + { + debug("RSA authentication accepted by server."); + BN_clear_free(e); + BN_clear_free(n); + BN_clear_free(challenge); + return 1; + } + + /* Otherwise it should return failure. */ + if (type != SSH_SMSG_FAILURE) + packet_disconnect("Protocol error waiting RSA auth response: %d", + type); + } + + BN_clear_free(e); + BN_clear_free(n); + BN_clear_free(challenge); + + debug("RSA authentication using agent refused."); + return 0; +} + +/* Computes the proper response to a RSA challenge, and sends the response to + the server. */ + +void +respond_to_rsa_challenge(BIGNUM *challenge, RSA *prv) +{ + unsigned char buf[32], response[16]; + MD5_CTX md; + int i, len; + + /* Decrypt the challenge using the private key. */ + rsa_private_decrypt(challenge, challenge, prv); + + /* Compute the response. */ + /* The response is MD5 of decrypted challenge plus session id. */ + len = BN_num_bytes(challenge); + assert(len <= sizeof(buf) && len); + memset(buf, 0, sizeof(buf)); + BN_bn2bin(challenge, buf + sizeof(buf) - len); + MD5_Init(&md); + MD5_Update(&md, buf, 32); + MD5_Update(&md, session_id, 16); + MD5_Final(response, &md); + + debug("Sending response to host key RSA challenge."); + + /* Send the response back to the server. */ + packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); + for (i = 0; i < 16; i++) + packet_put_char(response[i]); + packet_send(); + packet_write_wait(); + + memset(buf, 0, sizeof(buf)); + memset(response, 0, sizeof(response)); + memset(&md, 0, sizeof(md)); +} + +/* Checks if the user has authentication file, and if so, tries to authenticate + the user using it. */ + +int +try_rsa_authentication(struct passwd *pw, const char *authfile, + int may_ask_passphrase) +{ + BIGNUM *challenge; + RSA *private_key; + RSA *public_key; + char *passphrase, *comment; + int type, i; + int plen, clen; + + /* Try to load identification for the authentication key. */ + public_key = RSA_new(); + if (!load_public_key(authfile, public_key, &comment)) { + RSA_free(public_key); + return 0; /* Could not load it. Fail. */ + } + + debug("Trying RSA authentication with key '%.100s'", comment); + + /* Tell the server that we are willing to authenticate using this key. */ + packet_start(SSH_CMSG_AUTH_RSA); + packet_put_bignum(public_key->n); + packet_send(); + packet_write_wait(); + + /* We no longer need the public key. */ + RSA_free(public_key); + + /* Wait for server's response. */ + type = packet_read(&plen); + + /* The server responds with failure if it doesn\'t like our key or doesn\'t + support RSA authentication. */ + if (type == SSH_SMSG_FAILURE) + { + debug("Server refused our key."); + xfree(comment); + return 0; /* Server refuses to authenticate with this key. */ + } + + /* Otherwise, the server should respond with a challenge. */ + if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) + packet_disconnect("Protocol error during RSA authentication: %d", type); + + /* Get the challenge from the packet. */ + challenge = BN_new(); + packet_get_bignum(challenge, &clen); + + packet_integrity_check(plen, clen, type); + + debug("Received RSA challenge from server."); + + private_key = RSA_new(); + /* Load the private key. Try first with empty passphrase; if it fails, + ask for a passphrase. */ + if (!load_private_key(authfile, "", private_key, NULL)) + { + char buf[300]; + /* Request passphrase from the user. We read from /dev/tty to make + this work even if stdin has been redirected. If running in + batch mode, we just use the empty passphrase, which will fail and + return. */ + snprintf(buf, sizeof buf, + "Enter passphrase for RSA key '%.100s': ", comment); + if (may_ask_passphrase) + passphrase = read_passphrase(buf, 0); + else + { + debug("Will not query passphrase for %.100s in batch mode.", + comment); + passphrase = xstrdup(""); + } + + /* Load the authentication file using the pasphrase. */ + if (!load_private_key(authfile, passphrase, private_key, NULL)) + { + memset(passphrase, 0, strlen(passphrase)); + xfree(passphrase); + error("Bad passphrase."); + + /* Send a dummy response packet to avoid protocol error. */ + packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); + for (i = 0; i < 16; i++) + packet_put_char(0); + packet_send(); + packet_write_wait(); + + /* Expect the server to reject it... */ + packet_read_expect(&plen, SSH_SMSG_FAILURE); + xfree(comment); + return 0; + } + + /* Destroy the passphrase. */ + memset(passphrase, 0, strlen(passphrase)); + xfree(passphrase); + } + + /* We no longer need the comment. */ + xfree(comment); + + /* Compute and send a response to the challenge. */ + respond_to_rsa_challenge(challenge, private_key); + + /* Destroy the private key. */ + RSA_free(private_key); + + /* We no longer need the challenge. */ + BN_clear_free(challenge); + + /* Wait for response from the server. */ + type = packet_read(&plen); + if (type == SSH_SMSG_SUCCESS) + { + debug("RSA authentication accepted by server."); + return 1; + } + if (type != SSH_SMSG_FAILURE) + packet_disconnect("Protocol error waiting RSA auth response: %d", type); + debug("RSA authentication refused."); + return 0; +} + +/* Tries to authenticate the user using combined rhosts or /etc/hosts.equiv + authentication and RSA host authentication. */ + +int +try_rhosts_rsa_authentication(const char *local_user, RSA *host_key) +{ + int type; + BIGNUM *challenge; + int plen, clen; + + debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication."); + + /* Tell the server that we are willing to authenticate using this key. */ + packet_start(SSH_CMSG_AUTH_RHOSTS_RSA); + packet_put_string(local_user, strlen(local_user)); + packet_put_int(BN_num_bits(host_key->n)); + packet_put_bignum(host_key->e); + packet_put_bignum(host_key->n); + packet_send(); + packet_write_wait(); + + /* Wait for server's response. */ + type = packet_read(&plen); + + /* The server responds with failure if it doesn't admit our .rhosts + authentication or doesn't know our host key. */ + if (type == SSH_SMSG_FAILURE) + { + debug("Server refused our rhosts authentication or host key."); + return 0; /* Server refuses to authenticate us with this method. */ + } + + /* Otherwise, the server should respond with a challenge. */ + if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) + packet_disconnect("Protocol error during RSA authentication: %d", type); + + /* Get the challenge from the packet. */ + challenge = BN_new(); + packet_get_bignum(challenge, &clen); + + packet_integrity_check(plen, clen, type); + + debug("Received RSA challenge for host key from server."); + + /* Compute a response to the challenge. */ + respond_to_rsa_challenge(challenge, host_key); + + /* We no longer need the challenge. */ + BN_clear_free(challenge); + + /* Wait for response from the server. */ + type = packet_read(&plen); + if (type == SSH_SMSG_SUCCESS) + { + debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server."); + return 1; + } + if (type != SSH_SMSG_FAILURE) + packet_disconnect("Protocol error waiting RSA auth response: %d", type); + debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused."); + return 0; +} + +#ifdef KRB4 +int try_kerberos_authentication() +{ + KTEXT_ST auth; /* Kerberos data */ + char *reply; + char inst[INST_SZ]; + char *realm; + CREDENTIALS cred; + int r, type, plen; + Key_schedule schedule; + u_long checksum, cksum; + MSG_DAT msg_data; + struct sockaddr_in local, foreign; + struct stat st; + + /* Don't do anything if we don't have any tickets. */ + if (stat(tkt_string(), &st) < 0) return 0; + + strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ); + + realm = (char *)krb_realmofhost(get_canonical_hostname()); + if (!realm) { + debug("Kerberos V4: no realm for %s", get_canonical_hostname()); + return 0; + } + /* This can really be anything. */ + checksum = (u_long) getpid(); + + r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum); + if (r != KSUCCESS) { + debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]); + return 0; + } + /* Get session key to decrypt the server's reply with. */ + r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred); + if (r != KSUCCESS) { + debug("get_cred failed: %s", krb_err_txt[r]); + return 0; + } + des_key_sched((des_cblock *)cred.session, schedule); + + /* Send authentication info to server. */ + packet_start(SSH_CMSG_AUTH_KERBEROS); + packet_put_string((char *)auth.dat, auth.length); + packet_send(); + packet_write_wait(); + + /* Zero the buffer. */ + (void) memset(auth.dat, 0, MAX_KTXT_LEN); + + r = sizeof(local); + memset(&local, 0, sizeof(local)); + if (getsockname(packet_get_connection_in(), + (struct sockaddr *) &local, &r) < 0) + debug("getsockname failed: %s", strerror(errno)); + + r = sizeof(foreign); + memset(&foreign, 0, sizeof(foreign)); + if (getpeername(packet_get_connection_in(), + (struct sockaddr *)&foreign, &r) < 0) + debug("getpeername failed: %s", strerror(errno)); + + /* Get server reply. */ + type = packet_read(&plen); + switch(type) { + + case SSH_SMSG_FAILURE: /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */ + debug("Kerberos V4 authentication failed."); + return 0; + break; + + case SSH_SMSG_AUTH_KERBEROS_RESPONSE: /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */ + debug("Kerberos V4 authentication accepted."); + + /* Get server's response. */ + reply = packet_get_string((unsigned int *)&auth.length); + memcpy(auth.dat, reply, auth.length); + xfree(reply); + + packet_integrity_check(plen, 4 + auth.length, type); + + /* If his response isn't properly encrypted with the session key, + and the decrypted checksum fails to match, he's bogus. Bail out. */ + r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session, + &foreign, &local, &msg_data); + if (r != KSUCCESS) { + debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]); + packet_disconnect("Kerberos V4 challenge failed!"); + } + /* Fetch the (incremented) checksum that we supplied in the request. */ + (void)memcpy((char *)&cksum, (char *)msg_data.app_data, sizeof(cksum)); + cksum = ntohl(cksum); + + /* If it matches, we're golden. */ + if (cksum == checksum + 1) { + debug("Kerberos V4 challenge successful."); + return 1; + } + else + packet_disconnect("Kerberos V4 challenge failed!"); + break; + + default: + packet_disconnect("Protocol error on Kerberos V4 response: %d", type); + } + return 0; +} +#endif /* KRB4 */ + +#ifdef AFS +int send_kerberos_tgt() +{ + CREDENTIALS *creds; + char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ]; + int r, type, plen; + unsigned char buffer[8192]; + struct stat st; + + /* Don't do anything if we don't have any tickets. */ + if (stat(tkt_string(), &st) < 0) return 0; + + creds = xmalloc(sizeof(*creds)); + + if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) { + debug("Kerberos V4 tf_fullname failed: %s",krb_err_txt[r]); + return 0; + } + if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) { + debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]); + return 0; + } + if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) { + debug("Kerberos V4 ticket expired: %s", TKT_FILE); + return 0; + } + + creds_to_radix(creds, buffer); + xfree(creds); + + packet_start(SSH_CMSG_HAVE_KERBEROS_TGT); + packet_put_string((char *)buffer, strlen(buffer)); + packet_send(); + packet_write_wait(); + + type = packet_read(&plen); + + if (type == SSH_SMSG_FAILURE) + debug("Kerberos TGT for realm %s rejected.", prealm); + else if (type != SSH_SMSG_SUCCESS) + packet_disconnect("Protocol error on Kerberos TGT response: %d", type); + + return 1; +} + +void send_afs_tokens(void) +{ + CREDENTIALS creds; + struct ViceIoctl parms; + struct ClearToken ct; + int i, type, len, plen; + char buf[2048], *p, *server_cell; + unsigned char buffer[8192]; + + /* Move over ktc_GetToken, here's something leaner. */ + for (i = 0; i < 100; i++) { /* just in case */ + parms.in = (char *)&i; + parms.in_size = sizeof(i); + parms.out = buf; + parms.out_size = sizeof(buf); + if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0) break; + p = buf; + + /* Get secret token. */ + memcpy(&creds.ticket_st.length, p, sizeof(unsigned int)); + if (creds.ticket_st.length > MAX_KTXT_LEN) break; + p += sizeof(unsigned int); + memcpy(creds.ticket_st.dat, p, creds.ticket_st.length); + p += creds.ticket_st.length; + + /* Get clear token. */ + memcpy(&len, p, sizeof(len)); + if (len != sizeof(struct ClearToken)) break; + p += sizeof(len); + memcpy(&ct, p, len); + p += len; + p += sizeof(len); /* primary flag */ + server_cell = p; + + /* Flesh out our credentials. */ + strlcpy(creds.service, "afs", sizeof creds.service); + creds.instance[0] = '\0'; + strlcpy(creds.realm, server_cell, REALM_SZ); + memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ); + creds.issue_date = ct.BeginTimestamp; + creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp); + creds.kvno = ct.AuthHandle; + snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId); + creds.pinst[0] = '\0'; + + /* Encode token, ship it off. */ + if (!creds_to_radix(&creds, buffer)) break; + packet_start(SSH_CMSG_HAVE_AFS_TOKEN); + packet_put_string((char *)buffer, strlen(buffer)); + packet_send(); + packet_write_wait(); + + /* Roger, Roger. Clearance, Clarence. What's your vector, Victor? */ + type = packet_read(&plen); + + if (type == SSH_SMSG_FAILURE) + debug("AFS token for cell %s rejected.", server_cell); + else if (type != SSH_SMSG_SUCCESS) + packet_disconnect("Protocol error on AFS token response: %d", type); + } +} +#endif /* AFS */ + +/* Waits for the server identification string, and sends our own identification + string. */ + +void ssh_exchange_identification() +{ + char buf[256], remote_version[256]; /* must be same size! */ + int remote_major, remote_minor, i; + int connection_in = packet_get_connection_in(); + int connection_out = packet_get_connection_out(); + extern Options options; + + /* Read other side\'s version identification. */ + for (i = 0; i < sizeof(buf) - 1; i++) + { + if (read(connection_in, &buf[i], 1) != 1) + fatal("read: %.100s", strerror(errno)); + if (buf[i] == '\r') + { + buf[i] = '\n'; + buf[i + 1] = 0; + break; + } + if (buf[i] == '\n') + { + buf[i + 1] = 0; + break; + } + } + buf[sizeof(buf) - 1] = 0; + + /* Check that the versions match. In future this might accept several + versions and set appropriate flags to handle them. */ + if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, + remote_version) != 3) + fatal("Bad remote protocol version identification: '%.100s'", buf); + debug("Remote protocol version %d.%d, remote software version %.100s", + remote_major, remote_minor, remote_version); + + /* Check if the remote protocol version is too old. */ + if (remote_major == 1 && remote_minor < 3) + fatal("Remote machine has too old SSH software version."); + + /* We speak 1.3, too. */ + if (remote_major == 1 && remote_minor == 3) { + enable_compat13(); + if (options.forward_agent && strcmp(remote_version, SSH_VERSION) != 0) { + log("Agent forwarding disabled, remote version '%s' is not compatible.", + remote_version); + options.forward_agent = 0; + } + } +#if 0 + /* Removed for now, to permit compatibility with latter versions. The server + will reject our version and disconnect if it doesn't support it. */ + if (remote_major != PROTOCOL_MAJOR) + fatal("Protocol major versions differ: %d vs. %d", + PROTOCOL_MAJOR, remote_major); +#endif + + /* Send our own protocol version identification. */ + snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", + PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION); + if (write(connection_out, buf, strlen(buf)) != strlen(buf)) + fatal("write: %.100s", strerror(errno)); +} + +int ssh_cipher_default = SSH_CIPHER_3DES; + +int read_yes_or_no(const char *prompt, int defval) +{ + char buf[1024]; + FILE *f; + int retval = -1; + + if (isatty(0)) + f = stdin; + else + f = fopen("/dev/tty", "rw"); + + if (f == NULL) + return 0; + + fflush(stdout); + + while (1) + { + fprintf(stderr, "%s", prompt); + if (fgets(buf, sizeof(buf), f) == NULL) + { + /* Print a newline (the prompt probably didn\'t have one). */ + fprintf(stderr, "\n"); + strlcpy(buf, "no", sizeof buf); + } + /* Remove newline from response. */ + if (strchr(buf, '\n')) + *strchr(buf, '\n') = 0; + + if (buf[0] == 0) + retval = defval; + if (strcmp(buf, "yes") == 0) + retval = 1; + if (strcmp(buf, "no") == 0) + retval = 0; + + if (retval != -1) + { + if (f != stdin) + fclose(f); + return retval; + } + } +} + +/* Starts a dialog with the server, and authenticates the current user on the + server. This does not need any extra privileges. The basic connection + to the server must already have been established before this is called. + User is the remote user; if it is NULL, the current local user name will + be used. Anonymous indicates that no rhosts authentication will be used. + If login fails, this function prints an error and never returns. + This function does not require super-user privileges. */ + +void ssh_login(int host_key_valid, + RSA *own_host_key, + const char *orighost, + struct sockaddr_in *hostaddr, + Options *options, uid_t original_real_uid) +{ + int i, type; + char *password; + struct passwd *pw; + BIGNUM *key; + RSA *host_key, *file_key; + RSA *public_key; + unsigned char session_key[SSH_SESSION_KEY_LENGTH]; + const char *server_user, *local_user; + char *cp, *host, *ip = NULL; + unsigned char check_bytes[8]; + unsigned int supported_ciphers, supported_authentications, protocol_flags; + HostStatus host_status; + HostStatus ip_status; + int host_ip_differ = 0; + int local = (ntohl(hostaddr->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; + int payload_len, clen, sum_len = 0; + u_int32_t rand = 0; + + if (options->check_host_ip) + ip = xstrdup(inet_ntoa(hostaddr->sin_addr)); + + /* Convert the user-supplied hostname into all lowercase. */ + host = xstrdup(orighost); + for (cp = host; *cp; cp++) + if (isupper(*cp)) + *cp = tolower(*cp); + + /* Exchange protocol version identification strings with the server. */ + ssh_exchange_identification(); + + /* Put the connection into non-blocking mode. */ + packet_set_nonblocking(); + + /* Get local user name. Use it as server user if no user name + was given. */ + pw = getpwuid(original_real_uid); + if (!pw) + fatal("User id %d not found from user database.", original_real_uid); + local_user = xstrdup(pw->pw_name); + server_user = options->user ? options->user : local_user; + + debug("Waiting for server public key."); + + /* Wait for a public key packet from the server. */ + packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY); + + /* Get check bytes from the packet. */ + for (i = 0; i < 8; i++) + check_bytes[i] = packet_get_char(); + + /* Get the public key. */ + public_key = RSA_new(); + packet_get_int(); /* bits */ + public_key->e = BN_new(); + packet_get_bignum(public_key->e, &clen); + sum_len += clen; + public_key->n = BN_new(); + packet_get_bignum(public_key->n, &clen); + sum_len += clen; + + /* Get the host key. */ + host_key = RSA_new(); + packet_get_int(); /* bits */ + host_key->e = BN_new(); + packet_get_bignum(host_key->e, &clen); + sum_len += clen; + host_key->n = BN_new(); + packet_get_bignum(host_key->n, &clen); + sum_len += clen; + + /* Store the host key from the known host file in here + * so that we can compare it with the key for the IP + * address. */ + file_key = RSA_new(); + file_key->n = BN_new(); + file_key->e = BN_new(); + + /* Get protocol flags. */ + protocol_flags = packet_get_int(); + packet_set_protocol_flags(protocol_flags); + + /* Get supported cipher types. */ + supported_ciphers = packet_get_int(); + + /* Get supported authentication types. */ + supported_authentications = packet_get_int(); + + debug("Received server public key (%d bits) and host key (%d bits).", + BN_num_bits(public_key->n), BN_num_bits(host_key->n)); + + packet_integrity_check(payload_len, + 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4, + SSH_SMSG_PUBLIC_KEY); + + /* Compute the session id. */ + compute_session_id(session_id, check_bytes, + BN_num_bits(host_key->n), host_key->n, + BN_num_bits(public_key->n), public_key->n); + + /* Check if the host key is present in the user\'s list of known hosts + or in the systemwide list. */ + host_status = check_host_in_hostfile(options->user_hostfile, + host, BN_num_bits(host_key->n), + host_key->e, host_key->n, + file_key->e, file_key->n); + if (host_status == HOST_NEW) + host_status = check_host_in_hostfile(options->system_hostfile, host, + BN_num_bits(host_key->n), + host_key->e, host_key->n, + file_key->e, file_key->n); + /* Force accepting of the host key for localhost and 127.0.0.1. + The problem is that if the home directory is NFS-mounted to multiple + machines, localhost will refer to a different machine in each of them, + and the user will get bogus HOST_CHANGED warnings. This essentially + disables host authentication for localhost; however, this is probably + not a real problem. */ + if (local) { + debug("Forcing accepting of host key for localhost."); + host_status = HOST_OK; + } + + /* Also perform check for the ip address, skip the check if we are + localhost or the hostname was an ip address to begin with */ + if (options->check_host_ip && !local && strcmp(host, ip)) { + RSA *ip_key = RSA_new(); + ip_key->n = BN_new(); + ip_key->e = BN_new(); + ip_status = check_host_in_hostfile(options->user_hostfile, ip, + BN_num_bits(host_key->n), + host_key->e, host_key->n, + ip_key->e, ip_key->n); + + if (ip_status == HOST_NEW) + ip_status = check_host_in_hostfile(options->system_hostfile, ip, + BN_num_bits(host_key->n), + host_key->e, host_key->n, + ip_key->e, ip_key->n); + if (host_status == HOST_CHANGED && + (ip_status != HOST_CHANGED || + (BN_cmp(ip_key->e, file_key->e) || BN_cmp(ip_key->n, file_key->n)))) + host_ip_differ = 1; + + RSA_free(ip_key); + } else + ip_status = host_status; + + RSA_free(file_key); + + switch (host_status) { + case HOST_OK: + /* The host is known and the key matches. */ + debug("Host '%.200s' is known and matches the host key.", host); + if (options->check_host_ip) { + if (ip_status == HOST_NEW) { + if (!add_host_to_hostfile(options->user_hostfile, ip, + BN_num_bits(host_key->n), + host_key->e, host_key->n)) + log("Failed to add the host ip to the list of known hosts (%.30s).", + options->user_hostfile); + else + log("Warning: Permanently added host ip '%.30s' to the list of known hosts.", ip); + } else if (ip_status != HOST_OK) + log("Warning: the host key differ from the key of the ip address '%.30s' differs", ip); + } + + break; + case HOST_NEW: + { + char hostline[1000], *hostp = hostline; + /* The host is new. */ + if (options->strict_host_key_checking == 1) { + /* User has requested strict host key checking. We will not + add the host key automatically. The only alternative left + is to abort. */ + fatal("No host key is known for %.200s and you have requested strict checking.", host); + } else if (options->strict_host_key_checking == 2) { /* The default */ + char prompt[1024]; + snprintf(prompt, sizeof(prompt), + "The authenticity of host '%.200s' can't be established.\n" + "Are you sure you want to continue connecting (yes/no)? ", + host); + if (!read_yes_or_no(prompt, -1)) + fatal("Aborted by user!\n"); + } + + if (options->check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) + snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); + else + hostp = host; + + /* If not in strict mode, add the key automatically to the local + known_hosts file. */ + if (!add_host_to_hostfile(options->user_hostfile, hostp, + BN_num_bits(host_key->n), + host_key->e, host_key->n)) + log("Failed to add the host to the list of known hosts (%.500s).", + options->user_hostfile); + else + log("Warning: Permanently added '%.200s' to the list of known hosts.", + hostp); + break; + } + case HOST_CHANGED: + if (options->check_host_ip) { + if (host_ip_differ) { + error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); + error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); + error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); + error("The host key for %s has changed,", host); + error("but the key for the according IP address %s has", ip); + error("a different status. This could either mean that DNS"); + error("SPOOFING is happening or the IP address for the host"); + error("and its host key have changed at the same time"); + } + } + + /* The host key has changed. */ + error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); + error("@ WARNING: HOST IDENTIFICATION HAS CHANGED! @"); + error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); + error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); + error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); + error("It is also possible that the host key has just been changed."); + error("Please contact your system administrator."); + error("Add correct host key in %.100s to get rid of this message.", + options->user_hostfile); + + /* If strict host key checking is in use, the user will have to edit + the key manually and we can only abort. */ + if (options->strict_host_key_checking) + fatal("Host key for %.200s has changed and you have requested strict checking.", host); + + /* If strict host key checking has not been requested, allow the + connection but without password authentication or + agent forwarding. */ + if (options->password_authentication) { + error("Password authentication is disabled to avoid trojan horses."); + options->password_authentication = 0; + } + if (options->forward_agent) { + error("Agent forwarding is disabled to avoid trojan horses."); + options->forward_agent = 0; + } + /* XXX Should permit the user to change to use the new id. This could + be done by converting the host key to an identifying sentence, tell + that the host identifies itself by that sentence, and ask the user + if he/she whishes to accept the authentication. */ + break; + } + + if (options->check_host_ip) + xfree(ip); + + /* Generate a session key. */ + arc4random_stir(); + + /* Generate an encryption key for the session. The key is a 256 bit + random number, interpreted as a 32-byte key, with the least significant + 8 bits being the first byte of the key. */ + for (i = 0; i < 32; i++) { + if (i % 4 == 0) + rand = arc4random(); + session_key[i] = rand & 0xff; + rand >>= 8; + } + + /* According to the protocol spec, the first byte of the session key is + the highest byte of the integer. The session key is xored with the + first 16 bytes of the session id. */ + key = BN_new(); + BN_set_word(key, 0); + for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) + { + BN_lshift(key, key, 8); + if (i < 16) + BN_add_word(key, session_key[i] ^ session_id[i]); + else + BN_add_word(key, session_key[i]); + } + + /* Encrypt the integer using the public key and host key of the server + (key with smaller modulus first). */ + if (BN_cmp(public_key->n, host_key->n) < 0) + { + /* Public key has smaller modulus. */ + assert(BN_num_bits(host_key->n) >= + BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED); + + rsa_public_encrypt(key, key, public_key); + rsa_public_encrypt(key, key, host_key); + } + else + { + /* Host key has smaller modulus (or they are equal). */ + assert(BN_num_bits(public_key->n) >= + BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED); + + rsa_public_encrypt(key, key, host_key); + rsa_public_encrypt(key, key, public_key); + } + + if (options->cipher == SSH_CIPHER_NOT_SET) { + if (cipher_mask() & supported_ciphers & (1 << ssh_cipher_default)) + options->cipher = ssh_cipher_default; + else { + debug("Cipher %d not supported, using %.100s instead.", + cipher_name(ssh_cipher_default), + cipher_name(SSH_FALLBACK_CIPHER)); + options->cipher = SSH_FALLBACK_CIPHER; + } + } + + /* Check that the selected cipher is supported. */ + if (!(supported_ciphers & (1 << options->cipher))) + fatal("Selected cipher type %.100s not supported by server.", + cipher_name(options->cipher)); + + debug("Encryption type: %.100s", cipher_name(options->cipher)); + + /* Send the encrypted session key to the server. */ + packet_start(SSH_CMSG_SESSION_KEY); + packet_put_char(options->cipher); + + /* Send the check bytes back to the server. */ + for (i = 0; i < 8; i++) + packet_put_char(check_bytes[i]); + + /* Send the encrypted encryption key. */ + packet_put_bignum(key); + + /* Send protocol flags. */ + packet_put_int(SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN); + + /* Send the packet now. */ + packet_send(); + packet_write_wait(); + + /* Destroy the session key integer and the public keys since we no longer + need them. */ + BN_clear_free(key); + RSA_free(public_key); + RSA_free(host_key); + + debug("Sent encrypted session key."); + + /* Set the encryption key. */ + packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, + options->cipher, 1); + + /* We will no longer need the session key here. Destroy any extra copies. */ + memset(session_key, 0, sizeof(session_key)); + + /* Expect a success message from the server. Note that this message will + be received in encrypted form. */ + packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); + + debug("Received encrypted confirmation."); + + /* Send the name of the user to log in as on the server. */ + packet_start(SSH_CMSG_USER); + packet_put_string(server_user, strlen(server_user)); + packet_send(); + packet_write_wait(); + + /* The server should respond with success if no authentication is needed + (the user has no password). Otherwise the server responds with + failure. */ + type = packet_read(&payload_len); + if (type == SSH_SMSG_SUCCESS) + return; /* Connection was accepted without authentication. */ + if (type != SSH_SMSG_FAILURE) + packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER", + type); + +#ifdef AFS + /* Try Kerberos tgt passing if the server supports it. */ + if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) && + options->kerberos_tgt_passing) + { + if (options->cipher == SSH_CIPHER_NONE) + log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!"); + (void)send_kerberos_tgt(); + } + + /* Try AFS token passing if the server supports it. */ + if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) && + options->afs_token_passing && k_hasafs()) { + if (options->cipher == SSH_CIPHER_NONE) + log("WARNING: Encryption is disabled! Token will be transmitted in the clear!"); + send_afs_tokens(); + } +#endif /* AFS */ + +#ifdef KRB4 + if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) && + options->kerberos_authentication) + { + debug("Trying Kerberos authentication."); + if (try_kerberos_authentication()) { + /* The server should respond with success or failure. */ + type = packet_read(&payload_len); + if (type == SSH_SMSG_SUCCESS) + return; /* Successful connection. */ + if (type != SSH_SMSG_FAILURE) + packet_disconnect("Protocol error: got %d in response to Kerberos auth", type); + } + } +#endif /* KRB4 */ + + /* Use rhosts authentication if running in privileged socket and we do not + wish to remain anonymous. */ + if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) && + options->rhosts_authentication) + { + debug("Trying rhosts authentication."); + packet_start(SSH_CMSG_AUTH_RHOSTS); + packet_put_string(local_user, strlen(local_user)); + packet_send(); + packet_write_wait(); + + /* The server should respond with success or failure. */ + type = packet_read(&payload_len); + if (type == SSH_SMSG_SUCCESS) + return; /* Successful connection. */ + if (type != SSH_SMSG_FAILURE) + packet_disconnect("Protocol error: got %d in response to rhosts auth", + type); + } + + /* Try .rhosts or /etc/hosts.equiv authentication with RSA host + authentication. */ + if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) && + options->rhosts_rsa_authentication && host_key_valid) + { + if (try_rhosts_rsa_authentication(local_user, own_host_key)) + return; /* Successful authentication. */ + } + + /* Try RSA authentication if the server supports it. */ + if ((supported_authentications & (1 << SSH_AUTH_RSA)) && + options->rsa_authentication) + { + /* Try RSA authentication using the authentication agent. The agent + is tried first because no passphrase is needed for it, whereas + identity files may require passphrases. */ + if (try_agent_authentication()) + return; /* Successful connection. */ + + /* Try RSA authentication for each identity. */ + for (i = 0; i < options->num_identity_files; i++) + if (try_rsa_authentication(pw, options->identity_files[i], + !options->batch_mode)) + return; /* Successful connection. */ + } + + /* Try password authentication if the server supports it. */ + if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) && + options->password_authentication && !options->batch_mode) + { + char prompt[80]; + snprintf(prompt, sizeof(prompt), "%.30s@%.30s's password: ", + server_user, host); + debug("Doing password authentication."); + if (options->cipher == SSH_CIPHER_NONE) + log("WARNING: Encryption is disabled! Password will be transmitted in clear text."); + for (i = 0; i < options->number_of_password_prompts; i++) { + if (i != 0) + error("Permission denied, please try again."); + password = read_passphrase(prompt, 0); + packet_start(SSH_CMSG_AUTH_PASSWORD); + packet_put_string(password, strlen(password)); + memset(password, 0, strlen(password)); + xfree(password); + packet_send(); + packet_write_wait(); + + type = packet_read(&payload_len); + if (type == SSH_SMSG_SUCCESS) + return; /* Successful connection. */ + if (type != SSH_SMSG_FAILURE) + packet_disconnect("Protocol error: got %d in response to passwd auth", type); + } + } + + /* All authentication methods have failed. Exit with an error message. */ + fatal("Permission denied."); + /*NOTREACHED*/ +} diff --git a/sshd.8 b/sshd.8 new file mode 100644 index 00000000..d422d3af --- /dev/null +++ b/sshd.8 @@ -0,0 +1,781 @@ +.\" -*- nroff -*- +.\" +.\" sshd.8.in +.\" +.\" Author: Tatu Ylonen +.\" +.\" Copyright (c) 1995 Tatu Ylonen , Espoo, Finland +.\" All rights reserved +.\" +.\" Created: Sat Apr 22 21:55:14 1995 ylo +.\" +.\" $Id$ +.\" +.Dd September 25, 1999 +.Dt SSHD 8 +.Os +.Sh NAME +.Nm sshd +.Nd secure shell daemon +.Sh SYNOPSIS +.Nm sshd +.Op Fl diq +.Op Fl b Ar bits +.Op Fl f Ar config_file +.Op Fl g Ar login_grace_time +.Op Fl h Ar host_key_file +.Op Fl k Ar key_gen_time +.Op Fl p Ar port +.Sh DESCRIPTION +.Nm +(Secure Shell Daemon) is the daemon program for +.Xr ssh 1 . +Together these programs replace rlogin and rsh programs, and +provide secure encrypted communications between two untrusted hosts +over an insecure network. The programs are intended to be as easy to +install and use as possible. +.Pp +.Nm +is the daemon that listens for connections from clients. It is +normally started at boot from +.Pa /etc/rc . +It forks a new +daemon for each incoming connection. The forked daemons handle +key exchange, encryption, authentication, command execution, +and data exchange. +.Pp +.Nm +works as follows. Each host has a host-specific RSA key +(normally 1024 bits) used to identify the host. Additionally, when +the daemon starts, it generates a server RSA key (normally 768 bits). +This key is normally regenerated every hour if it has been used, and +is never stored on disk. +.Pp +Whenever a client connects the daemon, the daemon sends its host +and server public keys to the client. The client compares the +host key against its own database to verify that it has not changed. +The client then generates a 256 bit random number. It encrypts this +random number using both the host key and the server key, and sends +the encrypted number to the server. Both sides then start to use this +random number as a session key which is used to encrypt all further +communications in the session. The rest of the session is encrypted +using a conventional cipher, currently Blowfish and 3DES, with 3DES +being is used by default. The client selects the encryption algorithm +to use from those offered by the server. +.Pp +Next, the server and the client enter an authentication dialog. The +client tries to authenticate itself using +.Pa .rhosts +authentication, +.Pa .rhosts +authentication combined with RSA host +authentication, RSA challenge-response authentication, or password +based authentication. +.Pp +Rhosts authentication is normally disabled +because it is fundamentally insecure, but can be enabled in the server +configuration file if desired. System security is not improved unless +.Xr rshd 8 , +.Xr rlogind 8 , +.Xr rexecd 8 , +and +.Xr rexd 8 +are disabled (thus completely disabling +.Xr rlogin 1 +and +.Xr rsh 1 +into that machine). +.Pp +If the client successfully authenticates itself, a dialog for +preparing the session is entered. At this time the client may request +things like allocating a pseudo-tty, forwarding X11 connections, +forwarding TCP/IP connections, or forwarding the authentication agent +connection over the secure channel. +.Pp +Finally, the client either requests a shell or execution of a command. +The sides then enter session mode. In this mode, either side may send +data at any time, and such data is forwarded to/from the shell or +command on the server side, and the user terminal in the client side. +.Pp +When the user program terminates and all forwarded X11 and other +connections have been closed, the server sends command exit status to +the client, and both sides exit. +.Pp +.Nm +can be configured using command-line options or a configuration +file. Command-line options override values specified in the +configuration file. +.Pp +The options are as follows: +.Bl -tag -width Ds +.It Fl b Ar bits +Specifies the number of bits in the server key (default 768). +.Pp +.It Fl d +Debug mode. The server sends verbose debug output to the system +log, and does not put itself in the background. The server also will +not fork and will only process one connection. This option is only +intended for debugging for the server. +.It Fl f Ar configuration_file +Specifies the name of the configuration file. The default is +.Pa /etc/sshd_config . +.Nm +refuses to start if there is no configuration file. +.It Fl g Ar login_grace_time +Gives the grace time for clients to authenticate themselves (default +300 seconds). If the client fails to authenticate the user within +this many seconds, the server disconnects and exits. A value of zero +indicates no limit. +.It Fl h Ar host_key_file +Specifies the file from which the host key is read (default +.Pa /etc/ssh_host_key ) . +This option must be given if +.Nm +is not run as root (as the normal +host file is normally not readable by anyone but root). +.It Fl i +Specifies that +.Nm +is being run from inetd. +.Nm +is normally not run +from inetd because it needs to generate the server key before it can +respond to the client, and this may take tens of seconds. Clients +would have to wait too long if the key was regenerated every time. +However, with small key sizes (e.g. 512) using +.Nm +from inetd may +be feasible. +.It Fl k Ar key_gen_time +Specifies how often the server key is regenerated (default 3600 +seconds, or one hour). The motivation for regenerating the key fairly +often is that the key is not stored anywhere, and after about an hour, +it becomes impossible to recover the key for decrypting intercepted +communications even if the machine is cracked into or physically +seized. A value of zero indicates that the key will never be regenerated. +.It Fl p Ar port +Specifies the port on which the server listens for connections +(default 22). +.It Fl q +Quiet mode. Nothing is sent to the system log. Normally the beginning, +authentication, and termination of each connection is logged. +.It Fl Q +Do not print an error message if RSA support is missing. +.El +.Sh CONFIGURATION FILE +.Nm +reads configuration data from +.Pa /etc/sshd_config +(or the file specified with +.Fl f +on the command line). The file +contains keyword-value pairs, one per line. Lines starting with +.Ql # +and empty lines are interpreted as comments. +.Pp +The following keywords are possible. +.Bl -tag -width Ds +.It Cm AFSTokenPassing +Specifies whether an AFS token may be forwarded to the server. Default is +.Dq yes . +.It Cm AllowGroups +This keyword can be followed by a number of group names, separated +by spaces. If specified, login is allowed only for users whose primary +group matches one of the patterns. +.Ql \&* +and +.Ql ? +can be used as +wildcards in the patterns. Only group names are valid, a numerical group +id isn't recognized. By default login is allowed regardless of +the primary group. +.Pp +.It Cm AllowUsers +This keyword can be followed by a number of user names, separated +by spaces. If specified, login is allowed only for users names that +match one of the patterns. +.Ql \&* +and +.Ql ? +can be used as +wildcards in the patterns. Only user names are valid, a numerical user +id isn't recognized. By default login is allowed regardless of +the user name. +.Pp +.It Cm CheckMail +Specifies whether +.Nm +should check for new mail for interactive logins. +The default is +.Dq no . +.It Cm DenyGroups +This keyword can be followed by a number of group names, separated +by spaces. Users whose primary group matches one of the patterns +aren't allowed to log in. +.Ql \&* +and +.Ql ? +can be used as +wildcards in the patterns. Only group names are valid, a numerical group +id isn't recognized. By default login is allowed regardless of +the primary group. +.Pp +.It Cm DenyUsers +This keyword can be followed by a number of user names, separated +by spaces. Login is allowed disallowed for user names that match +one of the patterns. +.Ql \&* +and +.Ql ? +can be used as +wildcards in the patterns. Only user names are valid, a numerical user +id isn't recognized. By default login is allowed regardless of +the user name. +.Pp +.It Cm FascistLogging +Specifies whether to use verbose logging. Verbose logging violates +the privacy of users and is not recommended. The argument must be +.Dq yes +or +.Dq no . +The default is +.Dq no . +.It Cm HostKey +Specifies the file containing the private host key (default +.Pa /etc/ssh_host_key ) . +Note that +.Nm +does not start if this file is group/world-accessible. +.It Cm IgnoreRhosts +Specifies that rhosts and shosts files will not be used in +authentication. +.Pa /etc/hosts.equiv +and +.Pa /etc/shosts.equiv +are still used. The default is +.Dq no . +.It Cm KeepAlive +Specifies whether the system should send keepalive messages to the +other side. If they are sent, death of the connection or crash of one +of the machines will be properly noticed. However, this means that +connections will die if the route is down temporarily, and some people +find it annoying. On the other hand, if keepalives are not send, +sessions may hang indefinitely on the server, leaving +.Dq ghost +users and consuming server resources. +.Pp +The default is +.Dq yes +(to send keepalives), and the server will notice +if the network goes down or the client host reboots. This avoids +infinitely hanging sessions. +.Pp +To disable keepalives, the value should be set to +.Dq no +in both the server and the client configuration files. +.It Cm KerberosAuthentication +Specifies whether Kerberos authentication is allowed. This can +be in the form of a Kerberos ticket, or if +.Cm PasswordAuthentication +is yes, the password provided by the user will be validated through +the Kerberos KDC. Default is +.Dq yes . +.It Cm KerberosOrLocalPasswd +If set then if password authentication through Kerberos fails then +the password will be validated via any additional local mechanism +such as +.Pa /etc/passwd +or SecurID. Default is +.Dq yes . +.It Cm KerberosTgtPassing +Specifies whether a Kerberos TGT may be forwarded to the server. +Default is +.Dq no , +as this only works when the Kerberos KDC is actually an AFS kaserver. +.It Cm KerberosTicketCleanup +Specifies whether to automatically destroy the user's ticket cache +file on logout. Default is +.Dq yes . +.It Cm KeyRegenerationInterval +The server key is automatically regenerated after this many seconds +(if it has been used). The purpose of regeneration is to prevent +decrypting captured sessions by later breaking into the machine and +stealing the keys. The key is never stored anywhere. If the value is +0, the key is never regenerated. The default is 3600 +(seconds). +.It Cm ListenAddress +Specifies what local address +.Nm +should listen on. +The default is to listen to all local addresses. +.It Cm LoginGraceTime +The server disconnects after this time if the user has not +successfully logged in. If the value is 0, there is no time limit. +The default is 600 (seconds). +.It Cm PasswordAuthentication +Specifies whether password authentication is allowed. +The default is +.Dq yes . +.It Cm PermitEmptyPasswords +When password authentication is allowed, it specifies whether the +server allows login to accounts with empty password strings. The default +is +.Dq yes . +.It Cm PermitRootLogin +Specifies whether the root can log in using +.Xr ssh 1 . +The argument must be +.Dq yes , +.Dq without-password +or +.Dq no . +The default is +.Dq yes . +If this options is set to +.Dq without-password +only password authentication is disabled for root. +.Pp +Root login with RSA authentication when the +.Ar command +option has been +specified will be allowed regardless of the value of this setting +(which may be useful for taking remote backups even if root login is +normally not allowed). +.It Cm Port +Specifies the port number that +.Nm +listens on. The default is 22. +.It Cm PrintMotd +Specifies whether +.Nm +should print +.Pa /etc/motd +when a user logs in interactively. (On some systems it is also +printed by the shell, +.Pa /etc/profile , +or equivalent.) The default is +.Dq yes . +.It Cm QuietMode +Specifies whether the system runs in quiet mode. In quiet mode, +nothing is logged in the system log, except fatal errors. The default +is +.Dq no . +.It Cm RandomSeed +Obsolete. Random number generation uses other techniques. +.It Cm RhostsAuthentication +Specifies whether authentication using rhosts or /etc/hosts.equiv +files is sufficient. Normally, this method should not be permitted +because it is insecure. +.Cm RhostsRSAAuthentication +should be used +instead, because it performs RSA-based host authentication in addition +to normal rhosts or /etc/hosts.equiv authentication. +The default is +.Dq no . +.It Cm RhostsRSAAuthentication +Specifies whether rhosts or /etc/hosts.equiv authentication together +with successful RSA host authentication is allowed. The default is +.Dq yes . +.It Cm RSAAuthentication +Specifies whether pure RSA authentication is allowed. The default is +.Dq yes . +.It Cm ServerKeyBits +Defines the number of bits in the server key. The minimum value is +512, and the default is 768. +.It Cm SkeyAuthentication +Specifies whether +.Xr skey 1 +authentication is allowed. The default is +.Dq yes . +Note that s/key authentication is enabled only if +.Cm PasswordAuthentication +is allowed, too. +.It Cm StrictModes +Specifies whether +.Nm +should check file modes and ownership of the +user's files and home directory before accepting login. This +is normally desirable because novices sometimes accidentally leave their +directory or files world-writable. The default is +.Dq yes . +.It Cm SyslogFacility +Gives the facility code that is used when logging messages from +.Nm sshd . +The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, +LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. The default is AUTH. +.It Cm UseLogin +Specifies whether +.Xr login 1 +is used. The default is +.Dq no . +.It Cm X11Forwarding +Specifies whether X11 forwarding is permitted. The default is +.Dq yes . +Note that disabling X11 forwarding does not improve security in any +way, as users can always install their own forwarders. +.It Cm X11DisplayOffset +Specifies the first display number available for +.Nm sshd Ns 's +X11 forwarding. This prevents +.Nm +from interfering with real X11 servers. +.El +.Sh LOGIN PROCESS +When a user successfully logs in, +.Nm +does the following: +.Bl -enum -offset indent +.It +If the login is on a tty, and no command has been specified, +prints last login time and +.Pa /etc/motd +(unless prevented in the configuration file or by +.Pa $HOME/.hushlogin ; +see the +.Sx FILES +section). +.It +If the login is on a tty, records login time. +.It +Checks +.Pa /etc/nologin ; +if it exists, prints contents and quits +(unless root). +.It +Changes to run with normal user privileges. +.It +Sets up basic environment. +.It +Reads +.Pa $HOME/.ssh/environment +if it exists. +.It +Changes to user's home directory. +.It +If +.Pa $HOME/.ssh/rc +exists, runs it; else if +.Pa /etc/sshrc +exists, runs +it; otherwise runs xauth. The +.Dq rc +files are given the X11 +authentication protocol and cookie in standard input. +.It +Runs user's shell or command. +.El +.Sh AUTHORIZED_KEYS FILE FORMAT +The +.Pa $HOME/.ssh/authorized_keys +file lists the RSA keys that are +permitted for RSA authentication. Each line of the file contains one +key (empty lines and lines starting with a +.Ql # +are ignored as +comments). Each line consists of the following fields, separated by +spaces: options, bits, exponent, modulus, comment. The options field +is optional; its presence is determined by whether the line starts +with a number or not (the option field never starts with a number). +The bits, exponent, modulus and comment fields give the RSA key; the +comment field is not used for anything (but may be convenient for the +user to identify the key). +.Pp +Note that lines in this file are usually several hundred bytes long +(because of the size of the RSA key modulus). You don't want to type +them in; instead, copy the +.Pa identity.pub +file and edit it. +.Pp +The options (if present) consists of comma-separated option +specifications. No spaces are permitted, except within double quotes. +The following option specifications are supported: +.Bl -tag -width Ds +.It Cm from="pattern-list" +Specifies that in addition to RSA authentication, the canonical name +of the remote host must be present in the comma-separated list of +patterns ('*' and '?' serve as wildcards). The list may also contain +patterns negated by prefixing them with '!'; if the canonical host +name matches a negated pattern, the key is not accepted. The purpose +of this option is to optionally increase security: RSA authentication +by itself does not trust the network or name servers or anything (but +the key); however, if somebody somehow steals the key, the key +permits an intruder to log in from anywhere in the world. This +additional option makes using a stolen key more difficult (name +servers and/or routers would have to be compromised in addition to +just the key). +.It Cm command="command" +Specifies that the command is executed whenever this key is used for +authentication. The command supplied by the user (if any) is ignored. +The command is run on a pty if the connection requests a pty; +otherwise it is run without a tty. A quote may be included in the +command by quoting it with a backslash. This option might be useful +to restrict certain RSA keys to perform just a specific operation. An +example might be a key that permits remote backups but nothing +else. Notice that the client may specify TCP/IP and/or X11 +forwardings unless they are explicitly prohibited. +.It Cm environment="NAME=value" +Specifies that the string is to be added to the environment when +logging in using this key. Environment variables set this way +override other default environment values. Multiple options of this +type are permitted. +.It Cm no-port-forwarding +Forbids TCP/IP forwarding when this key is used for authentication. +Any port forward requests by the client will return an error. This +might be used, e.g., in connection with the +.Cm command +option. +.It Cm no-X11-forwarding +Forbids X11 forwarding when this key is used for authentication. +Any X11 forward requests by the client will return an error. +.It Cm no-agent-forwarding +Forbids authentication agent forwarding when this key is used for +authentication. +.It Cm no-pty +Prevents tty allocation (a request to allocate a pty will fail). +.El +.Ss Examples +1024 33 12121.\|.\|.\|312314325 ylo@foo.bar +.Pp +from="*.niksula.hut.fi,!pc.niksula.hut.fi" 1024 35 23.\|.\|.\|2334 ylo@niksula +.Pp +command="dump /home",no-pty,no-port-forwarding 1024 33 23.\|.\|.\|2323 backup.hut.fi +.Sh SSH_KNOWN_HOSTS FILE FORMAT +The +.Pa /etc/ssh_known_hosts +and +.Pa $HOME/.ssh/known_hosts +files contain host public keys for all known hosts. The global file should +be prepared by the admistrator (optional), and the per-user file is +maintained automatically: whenever the user connects an unknown host +its key is added to the per-user file. +.Pp +Each line in these files contains the following fields: hostnames, +bits, exponent, modulus, comment. The fields are separated by spaces. +.Pp +Hostnames is a comma-separated list of patterns ('*' and '?' act as +wildcards); each pattern in turn is matched against the canonical host +name (when authenticating a client) or against the user-supplied +name (when authenticating a server). A pattern may also be preceded +by +.Ql ! +to indicate negation: if the host name matches a negated +pattern, it is not accepted (by that line) even if it matched another +pattern on the line. +.Pp +Bits, exponent, and modulus are taken directly from the host key; they +can be obtained, e.g., from +.Pa /etc/ssh_host_key.pub . +The optional comment field continues to the end of the line, and is not used. +.Pp +Lines starting with +.Ql # +and empty lines are ignored as comments. +.Pp +When performing host authentication, authentication is accepted if any +matching line has the proper key. It is thus permissible (but not +recommended) to have several lines or different host keys for the same +names. This will inevitably happen when short forms of host names +from different domains are put in the file. It is possible +that the files contain conflicting information; authentication is +accepted if valid information can be found from either file. +.Pp +Note that the lines in these files are typically hundreds of characters +long, and you definitely don't want to type in the host keys by hand. +Rather, generate them by a script +or by taking +.Pa /etc/ssh_host_key.pub +and adding the host names at the front. +.Ss Examples +closenet,closenet.hut.fi,.\|.\|.\|,130.233.208.41 1024 37 159.\|.\|.93 closenet.hut.fi +.Sh FILES +.Bl -tag -width Ds +.It Pa /etc/sshd_config +Contains configuration data for +.Nm sshd . +This file should be writable by root only, but it is recommended +(though not necessary) that it be world-readable. +.It Pa /etc/ssh_host_key +Contains the private part of the host key. +This file should only be owned by root, readable only by root, and not +accessible to others. +Note that +.Nm +does not start if this file is group/world-accessible. +.It Pa /etc/ssh_host_key.pub +Contains the public part of the host key. +This file should be world-readable but writable only by +root. Its contents should match the private part. This file is not +really used for anything; it is only provided for the convenience of +the user so its contents can be copied to known hosts files. +These two files are created using +.Xr ssh-keygen 1 . +.It Pa /var/run/sshd.pid +Contains the process ID of the +.Nm +listening for connections (if there are several daemons running +concurrently for different ports, this contains the pid of the one +started last). The contents of this file are not sensitive; it can be +world-readable. +.It Pa $HOME/.ssh/authorized_keys +Lists the RSA keys that can be used to log into the user's account. +This file must be readable by root (which may on some machines imply +it being world-readable if the user's home directory resides on an NFS +volume). It is recommended that it not be accessible by others. The +format of this file is described above. +.It Pa /etc/ssh_known_hosts +This file is consulted when using rhosts with RSA host +authentication to check the public key of the host. The key must be +listed in this file to be accepted. +.It Pa $HOME/.ssh/known_hosts +The client uses this file +and +.Pa /etc/ssh_known_hosts +to verify that the remote host is the one we intended to +connect. These files should be writable only by root/the owner. +.Pa /etc/ssh_known_hosts +should be world-readable, and +.Pa $HOME/.ssh/known_hosts +can but need not be world-readable. +.It Pa /etc/nologin +If this file exists, +.Nm +refuses to let anyone except root log in. The contents of the file +are displayed to anyone trying to log in, and non-root connections are +refused. The file should be world-readable. +.It Pa /etc/hosts.allow, /etc/hosts.deny +If compiled with +.Sy LIBWRAP +support, tcp-wrappers access controls may be defined here as described in +.Xr hosts_access 5 . +.It Pa $HOME/.rhosts +This file contains host-username pairs, separated by a space, one per +line. The given user on the corresponding host is permitted to log in +without password. The same file is used by rlogind and rshd. +The file must +be writable only by the user; it is recommended that it not be +accessible by others. +.Pp +If is also possible to use netgroups in the file. Either host or user +name may be of the form +@groupname to specify all hosts or all users +in the group. +.It Pa $HOME/.shosts +For ssh, +this file is exactly the same as for +.Pa .rhosts . +However, this file is +not used by rlogin and rshd, so using this permits access using SSH only. +.Pa /etc/hosts.equiv +This file is used during +.Pa .rhosts +authentication. In the +simplest form, this file contains host names, one per line. Users on +those hosts are permitted to log in without a password, provided they +have the same user name on both machines. The host name may also be +followed by a user name; such users are permitted to log in as +.Em any +user on this machine (except root). Additionally, the syntax +.Dq +@group +can be used to specify netgroups. Negated entries start with +.Ql \&- . +.Pp +If the client host/user is successfully matched in this file, login is +automatically permitted provided the client and server user names are the +same. Additionally, successful RSA host authentication is normally +required. This file must be writable only by root; it is recommended +that it be world-readable. +.Pp +.Sy "Warning: It is almost never a good idea to use user names in" +.Pa hosts.equiv . +Beware that it really means that the named user(s) can log in as +.Em anybody , +which includes bin, daemon, adm, and other accounts that own critical +binaries and directories. Using a user name practically grants the +user root access. The only valid use for user names that I can think +of is in negative entries. +.Pp +Note that this warning also applies to rsh/rlogin. +.It Pa /etc/shosts.equiv +This is processed exactly as +.Pa /etc/hosts.equiv . +However, this file may be useful in environments that want to run both +rsh/rlogin and ssh. +.It Pa $HOME/.ssh/environment +This file is read into the environment at login (if it exists). It +can only contain empty lines, comment lines (that start with +.Ql # ) , +and assignment lines of the form name=value. The file should be writable +only by the user; it need not be readable by anyone else. +.It Pa $HOME/.ssh/rc +If this file exists, it is run with /bin/sh after reading the +environment files but before starting the user's shell or command. If +X11 spoofing is in use, this will receive the "proto cookie" pair in +standard input (and +.Ev DISPLAY +in environment). This must call +.Xr xauth 1 +in that case. +.Pp +The primary purpose of this file is to run any initialization routines +which may be needed before the user's home directory becomes +accessible; AFS is a particular example of such an environment. +.Pp +This file will probably contain some initialization code followed by +something similar to: "if read proto cookie; then echo add $DISPLAY +$proto $cookie | xauth -q -; fi". +.Pp +If this file does not exist, +.Pa /etc/sshrc +is run, and if that +does not exist either, xauth is used to store the cookie. +.Pp +This file should be writable only by the user, and need not be +readable by anyone else. +.It Pa /etc/sshrc +Like +.Pa $HOME/.ssh/rc . +This can be used to specify +machine-specific login-time initializations globally. This file +should be writable only by root, and should be world-readable. +.Sh AUTHOR +Tatu Ylonen +.Pp +Information about new releases, mailing lists, and other related +issues can be found from the SSH WWW home page: +.Pp +.Dl http://www.cs.hut.fi/ssh. +.Pp +OpenSSH +is a derivative of the original (free) ssh 1.2.12 release, but with bugs +removed and newer features re-added. Rapidly after the 1.2.12 release, +newer versions bore successively more restrictive licenses. This version +of OpenSSH +.Bl -bullet +.It +has all components of a restrictive nature (ie. patents, see +.Xr ssl 8 ) +directly removed from the source code; any licensed or patented components +are chosen from +external libraries. +.It +has been updated to support ssh protocol 1.5. +.It +contains added support for +.Xr kerberos 8 +authentication and ticket passing. +.It +supports one-time password authentication with +.Xr skey 1 . +.El +.Pp +The libraries described in +.Xr ssl 8 +are required for proper operation. +.Sh SEE ALSO +.Xr rlogin 1 , +.Xr rsh 1 , +.Xr scp 1 , +.Xr ssh 1 , +.Xr ssh-add 1 , +.Xr ssh-agent 1 , +.Xr ssh-keygen 1 , +.Xr ssl 8 diff --git a/sshd.c b/sshd.c new file mode 100644 index 00000000..1ff9c924 --- /dev/null +++ b/sshd.c @@ -0,0 +1,2445 @@ +/* + +sshd.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Fri Mar 17 17:09:28 1995 ylo + +This program is the ssh daemon. It listens for connections from clients, and +performs authentication, executes use commands or shell, and forwards +information to/from the application to the user client over an encrypted +connection. This can also handle forwarding of X11, TCP/IP, and authentication +agent connections. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "xmalloc.h" +#include "rsa.h" +#include "ssh.h" +#include "pty.h" +#include "packet.h" +#include "buffer.h" +#include "cipher.h" +#include "mpaux.h" +#include "servconf.h" +#include "uidswap.h" +#include "compat.h" + +#ifdef LIBWRAP +#include +#include +int allow_severity = LOG_INFO; +int deny_severity = LOG_WARNING; +#endif /* LIBWRAP */ + +#ifndef O_NOCTTY +#define O_NOCTTY 0 +#endif + +#ifdef KRB4 +char *ticket = NULL; +#endif /* KRB4 */ + +#ifdef HAVE_PAM +#include +struct pam_handle_t *pamh=NULL; +char *pampasswd=NULL; +int retval; +int origretval; +#endif /* HAVE_PAM */ + +/* Local Xauthority file. */ +char *xauthfile = NULL; + +/* Server configuration options. */ +ServerOptions options; + +/* Name of the server configuration file. */ +char *config_file_name = SERVER_CONFIG_FILE; + +/* Debug mode flag. This can be set on the command line. If debug + mode is enabled, extra debugging output will be sent to the system + log, the daemon will not go to background, and will exit after processing + the first connection. */ +int debug_flag = 0; + +/* Flag indicating that the daemon is being started from inetd. */ +int inetd_flag = 0; + +/* argv[0] without path. */ +char *av0; + +/* Saved arguments to main(). */ +char **saved_argv; + +/* This is set to the socket that the server is listening; this is used in + the SIGHUP signal handler. */ +int listen_sock; + +/* Flags set in auth-rsa from authorized_keys flags. These are set in + auth-rsa.c. */ +int no_port_forwarding_flag = 0; +int no_agent_forwarding_flag = 0; +int no_x11_forwarding_flag = 0; +int no_pty_flag = 0; +char *forced_command = NULL; /* RSA authentication "command=" option. */ +struct envstring *custom_environment = NULL; + /* RSA authentication "environment=" options. */ + +/* Session id for the current session. */ +unsigned char session_id[16]; + +/* Any really sensitive data in the application is contained in this structure. + The idea is that this structure could be locked into memory so that the + pages do not get written into swap. However, there are some problems. + The private key contains BIGNUMs, and we do not (in principle) have + access to the internals of them, and locking just the structure is not + very useful. Currently, memory locking is not implemented. */ +struct +{ + /* Private part of server key. */ + RSA *private_key; + + /* Private part of host key. */ + RSA *host_key; +} sensitive_data; + +/* Flag indicating whether the current session key has been used. This flag + is set whenever the key is used, and cleared when the key is regenerated. */ +int key_used = 0; + +/* This is set to true when SIGHUP is received. */ +int received_sighup = 0; + +/* Public side of the server key. This value is regenerated regularly with + the private key. */ +RSA *public_key; + +/* Prototypes for various functions defined later in this file. */ +void do_connection(int privileged_port); +void do_authentication(char *user, int privileged_port); +void do_authenticated(struct passwd *pw); +void do_exec_pty(const char *command, int ptyfd, int ttyfd, + const char *ttyname, struct passwd *pw, const char *term, + const char *display, const char *auth_proto, + const char *auth_data); +void do_exec_no_pty(const char *command, struct passwd *pw, + const char *display, const char *auth_proto, + const char *auth_data); +void do_child(const char *command, struct passwd *pw, const char *term, + const char *display, const char *auth_proto, + const char *auth_data, const char *ttyname); +#ifdef HAVE_PAM +static int pamconv(int num_msg, const struct pam_message **msg, + struct pam_response **resp, void *appdata_ptr); + +static struct pam_conv conv = { + pamconv, + NULL +}; + +static int pamconv(int num_msg, const struct pam_message **msg, + struct pam_response **resp, void *appdata_ptr) +{ + int count = 0; + int replies = 0; + struct pam_response *reply = NULL; + int size = sizeof(struct pam_response); + + for(count = 0; count < num_msg; count++) + { + switch (msg[count]->msg_style) + { + case PAM_PROMPT_ECHO_ON: + case PAM_PROMPT_ECHO_OFF: + if (reply == NULL) + reply = xmalloc(size); + else + reply = realloc(reply, size); + + if (reply == NULL) + return PAM_CONV_ERR; + + size += sizeof(struct pam_response); + + reply[replies].resp_retcode = PAM_SUCCESS; + + reply[replies++].resp = xstrdup(pampasswd); + /* PAM frees resp */ + break; + + case PAM_TEXT_INFO: + /* ignore it... */ + break; + + case PAM_ERROR_MSG: + default: + /* Must be an error of some sort... */ + if (reply != NULL) + free(reply); + + return PAM_CONV_ERR; + } + } + + if (reply != NULL) + *resp = reply; + + return PAM_SUCCESS; +} + +void pam_cleanup_proc(void *context) +{ + if (retval == PAM_SUCCESS) + retval = pam_close_session((pam_handle_t *)pamh, 0); + + if (pam_end((pam_handle_t *)pamh, retval) != PAM_SUCCESS) + log("Cannot release PAM authentication."); +} +#endif /* HAVE_PAM */ + +/* Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; + the effect is to reread the configuration file (and to regenerate + the server key). */ + +void sighup_handler(int sig) +{ + received_sighup = 1; + signal(SIGHUP, sighup_handler); +} + +/* Called from the main program after receiving SIGHUP. Restarts the + server. */ + +void sighup_restart() +{ + log("Received SIGHUP; restarting."); + close(listen_sock); + execv(saved_argv[0], saved_argv); + log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno)); + exit(1); +} + +/* Generic signal handler for terminating signals in the master daemon. + These close the listen socket; not closing it seems to cause "Address + already in use" problems on some machines, which is inconvenient. */ + +void sigterm_handler(int sig) +{ + log("Received signal %d; terminating.", sig); + close(listen_sock); + exit(255); +} + +/* SIGCHLD handler. This is called whenever a child dies. This will then + reap any zombies left by exited c. */ + +void main_sigchld_handler(int sig) +{ + int save_errno = errno; + int status; + wait(&status); + signal(SIGCHLD, main_sigchld_handler); + errno = save_errno; +} + +/* Signal handler for the alarm after the login grace period has expired. */ + +void grace_alarm_handler(int sig) +{ + /* Close the connection. */ + packet_close(); + + /* Log error and exit. */ + fatal("Timeout before authentication."); +} + +/* Signal handler for the key regeneration alarm. Note that this + alarm only occurs in the daemon waiting for connections, and it does not + do anything with the private key or random state before forking. Thus there + should be no concurrency control/asynchronous execution problems. */ + +void key_regeneration_alarm(int sig) +{ + int save_errno = errno; + + /* Check if we should generate a new key. */ + if (key_used) + { + /* This should really be done in the background. */ + log("Generating new %d bit RSA key.", options.server_key_bits); + + if (sensitive_data.private_key != NULL) + RSA_free(sensitive_data.private_key); + sensitive_data.private_key = RSA_new(); + + if (public_key != NULL) + RSA_free(public_key); + public_key = RSA_new(); + + rsa_generate_key(sensitive_data.private_key, public_key, + options.server_key_bits); + arc4random_stir(); + key_used = 0; + log("RSA key generation complete."); + } + + /* Reschedule the alarm. */ + signal(SIGALRM, key_regeneration_alarm); + alarm(options.key_regeneration_time); + errno = save_errno; +} + +/* Main program for the daemon. */ + +int +main(int ac, char **av) +{ + extern char *optarg; + extern int optind; + int opt, aux, sock_in, sock_out, newsock, i, pid, on = 1; + int remote_major, remote_minor; + int silentrsa = 0; + struct sockaddr_in sin; + char buf[100]; /* Must not be larger than remote_version. */ + char remote_version[100]; /* Must be at least as big as buf. */ + char *comment; + FILE *f; + struct linger linger; + + /* Save argv[0]. */ + saved_argv = av; + if (strchr(av[0], '/')) + av0 = strrchr(av[0], '/') + 1; + else + av0 = av[0]; + + /* Initialize configuration options to their default values. */ + initialize_server_options(&options); + + /* Parse command-line arguments. */ + while ((opt = getopt(ac, av, "f:p:b:k:h:g:diqQ")) != EOF) + { + switch (opt) + { + case 'f': + config_file_name = optarg; + break; + case 'd': + debug_flag = 1; + break; + case 'i': + inetd_flag = 1; + break; + case 'Q': + silentrsa = 1; + break; + case 'q': + options.quiet_mode = 1; + break; + case 'b': + options.server_key_bits = atoi(optarg); + break; + case 'p': + options.port = atoi(optarg); + break; + case 'g': + options.login_grace_time = atoi(optarg); + break; + case 'k': + options.key_regeneration_time = atoi(optarg); + break; + case 'h': + options.host_key_file = optarg; + break; + case '?': + default: + fprintf(stderr, "sshd version %s\n", SSH_VERSION); + fprintf(stderr, "Usage: %s [options]\n", av0); + fprintf(stderr, "Options:\n"); + fprintf(stderr, " -f file Configuration file (default %s/sshd_config)\n", ETCDIR); + fprintf(stderr, " -d Debugging mode\n"); + fprintf(stderr, " -i Started from inetd\n"); + fprintf(stderr, " -q Quiet (no logging)\n"); + fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); + fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); + fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n"); + fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); + fprintf(stderr, " -h file File from which to read host key (default: %s)\n", + HOST_KEY_FILE); + exit(1); + } + } + + /* check if RSA support exists */ + if (rsa_alive() == 0) { + if (silentrsa == 0) + printf("sshd: no RSA support in libssl and libcrypto -- exiting. See ssl(8)\n"); + log("no RSA support in libssl and libcrypto -- exiting. See ssl(8)"); + exit(1); + } + + /* Read server configuration options from the configuration file. */ + read_server_config(&options, config_file_name); + + /* Fill in default values for those options not explicitly set. */ + fill_default_server_options(&options); + + /* Check certain values for sanity. */ + if (options.server_key_bits < 512 || + options.server_key_bits > 32768) + { + fprintf(stderr, "Bad server key size.\n"); + exit(1); + } + if (options.port < 1 || options.port > 65535) + { + fprintf(stderr, "Bad port number.\n"); + exit(1); + } + + /* Check that there are no remaining arguments. */ + if (optind < ac) + { + fprintf(stderr, "Extra argument %s.\n", av[optind]); + exit(1); + } + + /* Initialize the log (it is reinitialized below in case we forked). */ + log_init(av0, debug_flag && !inetd_flag, + debug_flag || options.fascist_logging, + options.quiet_mode, options.log_facility); + + debug("sshd version %.100s", SSH_VERSION); + + sensitive_data.host_key = RSA_new(); + /* Load the host key. It must have empty passphrase. */ + if (!load_private_key(options.host_key_file, "", + sensitive_data.host_key, &comment)) + { + if (debug_flag) + fprintf(stderr, "Could not load host key: %s: %s\n", + options.host_key_file, strerror(errno)); + else + { + int err = errno; + log_init(av0, !inetd_flag, 1, 0, options.log_facility); + error("Could not load host key: %.200s: %.100s", + options.host_key_file, strerror(err)); + } + exit(1); + } + xfree(comment); + + /* If not in debugging mode, and not started from inetd, disconnect from + the controlling terminal, and fork. The original process exits. */ + if (!debug_flag && !inetd_flag) + { +#ifdef TIOCNOTTY + int fd; +#endif /* TIOCNOTTY */ + if (daemon(0, 0) < 0) + fatal("daemon() failed: %.200s", strerror(errno)); + + /* Disconnect from the controlling tty. */ +#ifdef TIOCNOTTY + fd = open("/dev/tty", O_RDWR|O_NOCTTY); + if (fd >= 0) + { + (void)ioctl(fd, TIOCNOTTY, NULL); + close(fd); + } +#endif /* TIOCNOTTY */ + } + + /* Reinitialize the log (because of the fork above). */ + log_init(av0, debug_flag && !inetd_flag, + debug_flag || options.fascist_logging, + options.quiet_mode, options.log_facility); + + /* Check that server and host key lengths differ sufficiently. This is + necessary to make double encryption work with rsaref. Oh, I hate + software patents. I dont know if this can go? Niels */ + if (options.server_key_bits > + BN_num_bits(sensitive_data.host_key->n) - SSH_KEY_BITS_RESERVED && + options.server_key_bits < + BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) + { + options.server_key_bits = + BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED; + debug("Forcing server key to %d bits to make it differ from host key.", + options.server_key_bits); + } + + /* Do not display messages to stdout in RSA code. */ + rsa_set_verbose(0); + + /* Initialize the random number generator. */ + arc4random_stir(); + + /* Chdir to the root directory so that the current disk can be unmounted + if desired. */ + chdir("/"); + + /* Close connection cleanly after attack. */ + cipher_attack_detected = packet_disconnect; + + /* Start listening for a socket, unless started from inetd. */ + if (inetd_flag) + { + int s1, s2; + s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ + s2 = dup(s1); + sock_in = dup(0); + sock_out = dup(1); + /* We intentionally do not close the descriptors 0, 1, and 2 as our + code for setting the descriptors won\'t work if ttyfd happens to + be one of those. */ + debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); + + public_key = RSA_new(); + sensitive_data.private_key = RSA_new(); + /* Generate an rsa key. */ + log("Generating %d bit RSA key.", options.server_key_bits); + rsa_generate_key(sensitive_data.private_key, public_key, + options.server_key_bits); + arc4random_stir(); + log("RSA key generation complete."); + } + else + { + /* Create socket for listening. */ + listen_sock = socket(AF_INET, SOCK_STREAM, 0); + if (listen_sock < 0) + fatal("socket: %.100s", strerror(errno)); + + /* Set socket options. We try to make the port reusable and have it + close as fast as possible without waiting in unnecessary wait states + on close. */ + setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, + sizeof(on)); + linger.l_onoff = 1; + linger.l_linger = 5; + setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, (void *)&linger, + sizeof(linger)); + + /* Initialize the socket address. */ + memset(&sin, 0, sizeof(sin)); + sin.sin_family = AF_INET; + sin.sin_addr = options.listen_addr; + sin.sin_port = htons(options.port); + + /* Bind the socket to the desired port. */ + if (bind(listen_sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) + { + error("bind: %.100s", strerror(errno)); + shutdown(listen_sock, SHUT_RDWR); + close(listen_sock); + fatal("Bind to port %d failed.", options.port); + } + + if (!debug_flag) + { + /* Record our pid in /etc/sshd_pid to make it easier to kill the + correct sshd. We don\'t want to do this before the bind above + because the bind will fail if there already is a daemon, and this + will overwrite any old pid in the file. */ + f = fopen(SSH_DAEMON_PID_FILE, "w"); + if (f) + { + fprintf(f, "%u\n", (unsigned int)getpid()); + fclose(f); + } + } + + /* Start listening on the port. */ + log("Server listening on port %d.", options.port); + if (listen(listen_sock, 5) < 0) + fatal("listen: %.100s", strerror(errno)); + + public_key = RSA_new(); + sensitive_data.private_key = RSA_new(); + /* Generate an rsa key. */ + log("Generating %d bit RSA key.", options.server_key_bits); + rsa_generate_key(sensitive_data.private_key, public_key, + options.server_key_bits); + arc4random_stir(); + log("RSA key generation complete."); + + /* Schedule server key regeneration alarm. */ + signal(SIGALRM, key_regeneration_alarm); + alarm(options.key_regeneration_time); + + /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ + signal(SIGHUP, sighup_handler); + signal(SIGTERM, sigterm_handler); + signal(SIGQUIT, sigterm_handler); + + /* Arrange SIGCHLD to be caught. */ + signal(SIGCHLD, main_sigchld_handler); + + /* Stay listening for connections until the system crashes or the + daemon is killed with a signal. */ + for (;;) + { + if (received_sighup) + sighup_restart(); + /* Wait in accept until there is a connection. */ + aux = sizeof(sin); + newsock = accept(listen_sock, (struct sockaddr *)&sin, &aux); + if (received_sighup) + sighup_restart(); + if (newsock < 0) + { + if (errno == EINTR) + continue; + error("accept: %.100s", strerror(errno)); + continue; + } + + /* Got connection. Fork a child to handle it, unless we are in + debugging mode. */ + if (debug_flag) + { + /* In debugging mode. Close the listening socket, and start + processing the connection without forking. */ + debug("Server will not fork when running in debugging mode."); + close(listen_sock); + sock_in = newsock; + sock_out = newsock; + pid = getpid(); + break; + } + else + { + /* Normal production daemon. Fork, and have the child process + the connection. The parent continues listening. */ + if ((pid = fork()) == 0) + { + /* Child. Close the listening socket, and start using + the accepted socket. Reinitialize logging (since our + pid has changed). We break out of the loop to handle + the connection. */ + close(listen_sock); + sock_in = newsock; + sock_out = newsock; + log_init(av0, debug_flag && !inetd_flag, + options.fascist_logging || debug_flag, + options.quiet_mode, options.log_facility); + break; + } + } + + /* Parent. Stay in the loop. */ + if (pid < 0) + error("fork: %.100s", strerror(errno)); + else + debug("Forked child %d.", pid); + + /* Mark that the key has been used (it was "given" to the child). */ + key_used = 1; + + arc4random_stir(); + + /* Close the new socket (the child is now taking care of it). */ + close(newsock); + } + } + + /* This is the child processing a new connection. */ + + /* Disable the key regeneration alarm. We will not regenerate the key + since we are no longer in a position to give it to anyone. We will + not restart on SIGHUP since it no longer makes sense. */ + alarm(0); + signal(SIGALRM, SIG_DFL); + signal(SIGHUP, SIG_DFL); + signal(SIGTERM, SIG_DFL); + signal(SIGQUIT, SIG_DFL); + signal(SIGCHLD, SIG_DFL); + + /* Set socket options for the connection. We want the socket to close + as fast as possible without waiting for anything. If the connection + is not a socket, these will do nothing. */ + /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ + linger.l_onoff = 1; + linger.l_linger = 5; + setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); + + /* Register our connection. This turns encryption off because we do not + have a key. */ + packet_set_connection(sock_in, sock_out); + + /* Check whether logins are denied from this host. */ +#ifdef LIBWRAP + { + struct request_info req; + + request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL); + fromhost(&req); + + if (!hosts_access(&req)) { + close(sock_in); + close(sock_out); + refuse(&req); + } + log("Connection from %.500s port %d", + eval_client(&req), get_remote_port()); + } +#else + /* Log the connection. */ + log("Connection from %.100s port %d", + get_remote_ipaddr(), get_remote_port()); +#endif /* LIBWRAP */ + + /* We don\'t want to listen forever unless the other side successfully + authenticates itself. So we set up an alarm which is cleared after + successful authentication. A limit of zero indicates no limit. + Note that we don\'t set the alarm in debugging mode; it is just annoying + to have the server exit just when you are about to discover the bug. */ + signal(SIGALRM, grace_alarm_handler); + if (!debug_flag) + alarm(options.login_grace_time); + + /* Send our protocol version identification. */ + snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", + PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION); + if (write(sock_out, buf, strlen(buf)) != strlen(buf)) + fatal("Could not write ident string."); + + /* Read other side\'s version identification. */ + for (i = 0; i < sizeof(buf) - 1; i++) + { + if (read(sock_in, &buf[i], 1) != 1) + fatal("Did not receive ident string."); + if (buf[i] == '\r') + { + buf[i] = '\n'; + buf[i + 1] = 0; + break; + } + if (buf[i] == '\n') + { + /* buf[i] == '\n' */ + buf[i + 1] = 0; + break; + } + } + buf[sizeof(buf) - 1] = 0; + + /* Check that the versions match. In future this might accept several + versions and set appropriate flags to handle them. */ + if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, + remote_version) != 3) + { + const char *s = "Protocol mismatch.\n"; + (void) write(sock_out, s, strlen(s)); + close(sock_in); + close(sock_out); + fatal("Bad protocol version identification: %.100s", buf); + } + debug("Client protocol version %d.%d; client software version %.100s", + remote_major, remote_minor, remote_version); + if (remote_major != PROTOCOL_MAJOR) + { + const char *s = "Protocol major versions differ.\n"; + (void) write(sock_out, s, strlen(s)); + close(sock_in); + close(sock_out); + fatal("Protocol major versions differ: %d vs. %d", + PROTOCOL_MAJOR, remote_major); + } + + /* Check that the client has sufficiently high software version. */ + if (remote_major == 1 && remote_minor < 3) + packet_disconnect("Your ssh version is too old and is no longer supported. Please install a newer version."); + + if (remote_major == 1 && remote_minor == 3) { + enable_compat13(); + if (strcmp(remote_version, "OpenSSH-1.1") != 0) { + debug("Agent forwarding disabled, remote version is not compatible."); + no_agent_forwarding_flag = 1; + } + } + + packet_set_nonblocking(); + + /* Handle the connection. We pass as argument whether the connection + came from a privileged port. */ + do_connection(get_remote_port() < IPPORT_RESERVED); + +#ifdef KRB4 + /* Cleanup user's ticket cache file. */ + if (options.kerberos_ticket_cleanup) + (void) dest_tkt(); +#endif /* KRB4 */ + + /* Cleanup user's local Xauthority file. */ + if (xauthfile) unlink(xauthfile); + + /* The connection has been terminated. */ + log("Closing connection to %.100s", inet_ntoa(sin.sin_addr)); + +#ifdef HAVE_PAM + if (retval == PAM_SUCCESS) + retval = pam_close_session((pam_handle_t *)pamh, 0); + + if (pam_end((pam_handle_t *)pamh, retval) != PAM_SUCCESS) + log("Cannot release PAM authentication."); + + fatal_remove_cleanup(&pam_cleanup_proc, NULL); +#endif /* HAVE_PAM */ + + packet_close(); + + exit(0); +} + +/* Process an incoming connection. Protocol version identifiers have already + been exchanged. This sends server key and performs the key exchange. + Server and host keys will no longer be needed after this functions. */ + +void do_connection(int privileged_port) +{ + int i; + BIGNUM *session_key_int; + unsigned char session_key[SSH_SESSION_KEY_LENGTH]; + unsigned char check_bytes[8]; + char *user; + unsigned int cipher_type, auth_mask, protocol_flags; + int plen, slen; + u_int32_t rand = 0; + + /* Generate check bytes that the client must send back in the user packet + in order for it to be accepted; this is used to defy ip spoofing + attacks. Note that this only works against somebody doing IP spoofing + from a remote machine; any machine on the local network can still see + outgoing packets and catch the random cookie. This only affects + rhosts authentication, and this is one of the reasons why it is + inherently insecure. */ + for (i = 0; i < 8; i++) { + if (i % 4 == 0) + rand = arc4random(); + check_bytes[i] = rand & 0xff; + rand >>= 8; + } + + /* Send our public key. We include in the packet 64 bits of random + data that must be matched in the reply in order to prevent IP spoofing. */ + packet_start(SSH_SMSG_PUBLIC_KEY); + for (i = 0; i < 8; i++) + packet_put_char(check_bytes[i]); + + /* Store our public server RSA key. */ + packet_put_int(BN_num_bits(public_key->n)); + packet_put_bignum(public_key->e); + packet_put_bignum(public_key->n); + + /* Store our public host RSA key. */ + packet_put_int(BN_num_bits(sensitive_data.host_key->n)); + packet_put_bignum(sensitive_data.host_key->e); + packet_put_bignum(sensitive_data.host_key->n); + + /* Put protocol flags. */ + packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); + + /* Declare which ciphers we support. */ + packet_put_int(cipher_mask()); + + /* Declare supported authentication types. */ + auth_mask = 0; + if (options.rhosts_authentication) + auth_mask |= 1 << SSH_AUTH_RHOSTS; + if (options.rhosts_rsa_authentication) + auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; + if (options.rsa_authentication) + auth_mask |= 1 << SSH_AUTH_RSA; +#ifdef KRB4 + if (options.kerberos_authentication) + auth_mask |= 1 << SSH_AUTH_KERBEROS; +#endif +#ifdef AFS + if (options.kerberos_tgt_passing) + auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; + if (options.afs_token_passing) + auth_mask |= 1 << SSH_PASS_AFS_TOKEN; +#endif + if (options.password_authentication) + auth_mask |= 1 << SSH_AUTH_PASSWORD; + packet_put_int(auth_mask); + + /* Send the packet and wait for it to be sent. */ + packet_send(); + packet_write_wait(); + + debug("Sent %d bit public key and %d bit host key.", + BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n)); + + /* Read clients reply (cipher type and session key). */ + packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); + + /* Get cipher type. */ + cipher_type = packet_get_char(); + + /* Get check bytes from the packet. These must match those we sent earlier + with the public key packet. */ + for (i = 0; i < 8; i++) + if (check_bytes[i] != packet_get_char()) + packet_disconnect("IP Spoofing check bytes do not match."); + + debug("Encryption type: %.200s", cipher_name(cipher_type)); + + /* Get the encrypted integer. */ + session_key_int = BN_new(); + packet_get_bignum(session_key_int, &slen); + + /* Get protocol flags. */ + protocol_flags = packet_get_int(); + packet_set_protocol_flags(protocol_flags); + + packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); + + /* Decrypt it using our private server key and private host key (key with + larger modulus first). */ + if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) + { + /* Private key has bigger modulus. */ + assert(BN_num_bits(sensitive_data.private_key->n) >= + BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED); + rsa_private_decrypt(session_key_int, session_key_int, + sensitive_data.private_key); + rsa_private_decrypt(session_key_int, session_key_int, + sensitive_data.host_key); + } + else + { + /* Host key has bigger modulus (or they are equal). */ + assert(BN_num_bits(sensitive_data.host_key->n) >= + BN_num_bits(sensitive_data.private_key->n) + + SSH_KEY_BITS_RESERVED); + rsa_private_decrypt(session_key_int, session_key_int, + sensitive_data.host_key); + rsa_private_decrypt(session_key_int, session_key_int, + sensitive_data.private_key); + } + + /* Compute session id for this session. */ + compute_session_id(session_id, check_bytes, + BN_num_bits(sensitive_data.host_key->n), + sensitive_data.host_key->n, + BN_num_bits(sensitive_data.private_key->n), + sensitive_data.private_key->n); + + /* Extract session key from the decrypted integer. The key is in the + least significant 256 bits of the integer; the first byte of the + key is in the highest bits. */ + BN_mask_bits(session_key_int, sizeof(session_key) * 8); + assert(BN_num_bytes(session_key_int) == sizeof(session_key)); + BN_bn2bin(session_key_int, session_key); + + /* Xor the first 16 bytes of the session key with the session id. */ + for (i = 0; i < 16; i++) + session_key[i] ^= session_id[i]; + + /* Destroy the decrypted integer. It is no longer needed. */ + BN_clear_free(session_key_int); + + /* Set the session key. From this on all communications will be + encrypted. */ + packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, + cipher_type, 0); + + /* Destroy our copy of the session key. It is no longer needed. */ + memset(session_key, 0, sizeof(session_key)); + + debug("Received session key; encryption turned on."); + + /* Send an acknowledgement packet. Note that this packet is sent + encrypted. */ + packet_start(SSH_SMSG_SUCCESS); + packet_send(); + packet_write_wait(); + + /* Get the name of the user that we wish to log in as. */ + packet_read_expect(&plen, SSH_CMSG_USER); + + /* Get the user name. */ + { + int ulen; + user = packet_get_string(&ulen); + packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER); + } + + /* Destroy the private and public keys. They will no longer be needed. */ + RSA_free(public_key); + RSA_free(sensitive_data.private_key); + RSA_free(sensitive_data.host_key); + + setproctitle("%s", user); + /* Do the authentication. */ + do_authentication(user, privileged_port); +} + +/* Check if the user is allowed to log in via ssh. If user is listed in + DenyUsers or user's primary group is listed in DenyGroups, false will + be returned. If AllowUsers isn't empty and user isn't listed there, or + if AllowGroups isn't empty and user isn't listed there, false will be + returned. Otherwise true is returned. + XXX This function should also check if user has a valid shell */ + +static int +allowed_user(struct passwd *pw) +{ + struct group *grp; + int i; + + /* Shouldn't be called if pw is NULL, but better safe than sorry... */ + if (!pw) + return 0; + + /* XXX Should check for valid login shell */ + + /* Return false if user is listed in DenyUsers */ + if (options.num_deny_users > 0) + { + if (!pw->pw_name) + return 0; + for (i = 0; i < options.num_deny_users; i++) + if (match_pattern(pw->pw_name, options.deny_users[i])) + return 0; + } + + /* Return false if AllowUsers isn't empty and user isn't listed there */ + if (options.num_allow_users > 0) + { + if (!pw->pw_name) + return 0; + for (i = 0; i < options.num_allow_users; i++) + if (match_pattern(pw->pw_name, options.allow_users[i])) + break; + /* i < options.num_allow_users iff we break for loop */ + if (i >= options.num_allow_users) + return 0; + } + + /* Get the primary group name if we need it. Return false if it fails */ + if (options.num_deny_groups > 0 || options.num_allow_groups > 0 ) + { + grp = getgrgid(pw->pw_gid); + if (!grp) + return 0; + + /* Return false if user's group is listed in DenyGroups */ + if (options.num_deny_groups > 0) + { + if (!grp->gr_name) + return 0; + for (i = 0; i < options.num_deny_groups; i++) + if (match_pattern(grp->gr_name, options.deny_groups[i])) + return 0; + } + + /* Return false if AllowGroups isn't empty and user's group isn't + listed there */ + if (options.num_allow_groups > 0) + { + if (!grp->gr_name) + return 0; + for (i = 0; i < options.num_allow_groups; i++) + if (match_pattern(grp->gr_name, options.allow_groups[i])) + break; + /* i < options.num_allow_groups iff we break for loop */ + if (i >= options.num_allow_groups) + return 0; + } + } + + /* We found no reason not to let this user try to log on... */ + return 1; +} + +/* Performs authentication of an incoming connection. Session key has already + been exchanged and encryption is enabled. User is the user name to log + in as (received from the clinet). Privileged_port is true if the + connection comes from a privileged port (used for .rhosts authentication).*/ + +#define MAX_AUTH_FAILURES 5 + +void +do_authentication(char *user, int privileged_port) +{ + int type; + int authenticated = 0; + int authentication_failures = 0; + char *password; + struct passwd *pw, pwcopy; + char *client_user; + unsigned int client_host_key_bits; + BIGNUM *client_host_key_e, *client_host_key_n; +#ifdef HAVE_PAM + int pam_auth_ok; +#endif /* HAVE_PAM */ + +#ifdef AFS + /* If machine has AFS, set process authentication group. */ + if (k_hasafs()) { + k_setpag(); + k_unlog(); + } +#endif /* AFS */ + + /* Verify that the user is a valid user. */ + pw = getpwnam(user); +#ifdef HAVE_PAM + if ((pw != NULL) && allowed_user(pw)) + { + /* Initialise PAM */ + retval = pam_start("ssh", pw->pw_name, &conv, (pam_handle_t **)&pamh); + fatal_add_cleanup(&pam_cleanup_proc, NULL); + origretval = retval; + if (retval == PAM_SUCCESS) + pam_auth_ok = 1; + } + + if (pam_auth_ok == 0) +#else /* HAVE_PAM */ + if (!pw || !allowed_user(pw)) +#endif /* HAVE_PAM */ + { + /* The user does not exist or access is denied, + but fake indication that authentication is needed. */ + packet_start(SSH_SMSG_FAILURE); + packet_send(); + packet_write_wait(); + + /* Keep reading packets, and always respond with a failure. This is to + avoid disclosing whether such a user really exists. */ + for (;;) + { + /* Read a packet. This will not return if the client disconnects. */ + int plen; + int type = packet_read(&plen); +#ifdef SKEY + int passw_len; + char *password, *skeyinfo; + if (options.password_authentication && + options.skey_authentication == 1 && + type == SSH_CMSG_AUTH_PASSWORD && + (password = packet_get_string(&passw_len)) != NULL && + passw_len == 5 && + strncasecmp(password, "s/key", 5) == 0 && + (skeyinfo = skey_fake_keyinfo(user)) != NULL ){ + /* Send a fake s/key challenge. */ + packet_send_debug(skeyinfo); + } +#endif + /* Send failure. This should be indistinguishable from a failed + authentication. */ + packet_start(SSH_SMSG_FAILURE); + packet_send(); + packet_write_wait(); + if (++authentication_failures >= MAX_AUTH_FAILURES) { + packet_disconnect("Too many authentication failures for %.100s from %.200s", + user, get_canonical_hostname()); + } + } + /*NOTREACHED*/ + abort(); + } + + /* Take a copy of the returned structure. */ + memset(&pwcopy, 0, sizeof(pwcopy)); + pwcopy.pw_name = xstrdup(pw->pw_name); + pwcopy.pw_passwd = xstrdup(pw->pw_passwd); + pwcopy.pw_uid = pw->pw_uid; + pwcopy.pw_gid = pw->pw_gid; + pwcopy.pw_dir = xstrdup(pw->pw_dir); + pwcopy.pw_shell = xstrdup(pw->pw_shell); + pw = &pwcopy; + + /* If we are not running as root, the user must have the same uid as the + server. */ + if (getuid() != 0 && pw->pw_uid != getuid()) + packet_disconnect("Cannot change user when server not running as root."); + + debug("Attempting authentication for %.100s.", user); + + /* If the user has no password, accept authentication immediately. */ + if (options.password_authentication && +#ifdef KRB4 + (!options.kerberos_authentication || options.kerberos_or_local_passwd) && +#endif /* KRB4 */ + auth_password(pw, "")) + { + /* Authentication with empty password succeeded. */ + debug("Login for user %.100s accepted without authentication.", user); + /* authentication_type = SSH_AUTH_PASSWORD; */ + authenticated = 1; + /* Success packet will be sent after loop below. */ + } + else + { + /* Indicate that authentication is needed. */ + packet_start(SSH_SMSG_FAILURE); + packet_send(); + packet_write_wait(); + } + + /* Loop until the user has been authenticated or the connection is closed. */ + while (!authenticated) + { + int plen; + /* Get a packet from the client. */ + type = packet_read(&plen); + + /* Process the packet. */ + switch (type) + { + +#ifdef AFS + case SSH_CMSG_HAVE_KERBEROS_TGT: + if (!options.kerberos_tgt_passing) + { + /* packet_get_all(); */ + log("Kerberos tgt passing disabled."); + break; + } + else { + /* Accept Kerberos tgt. */ + int dlen; + char *tgt = packet_get_string(&dlen); + packet_integrity_check(plen, 4 + dlen, type); + if (!auth_kerberos_tgt(pw, tgt)) + debug("Kerberos tgt REFUSED for %s", user); + xfree(tgt); + } + continue; + + case SSH_CMSG_HAVE_AFS_TOKEN: + if (!options.afs_token_passing || !k_hasafs()) { + /* packet_get_all(); */ + log("AFS token passing disabled."); + break; + } + else { + /* Accept AFS token. */ + int dlen; + char *token_string = packet_get_string(&dlen); + packet_integrity_check(plen, 4 + dlen, type); + if (!auth_afs_token(user, pw->pw_uid, token_string)) + debug("AFS token REFUSED for %s", user); + xfree(token_string); + continue; + } +#endif /* AFS */ + +#ifdef KRB4 + case SSH_CMSG_AUTH_KERBEROS: + if (!options.kerberos_authentication) + { + /* packet_get_all(); */ + log("Kerberos authentication disabled."); + break; + } + else { + /* Try Kerberos v4 authentication. */ + KTEXT_ST auth; + char *tkt_user = NULL; + char *kdata = packet_get_string((unsigned int *)&auth.length); + packet_integrity_check(plen, 4 + auth.length, type); + + if (auth.length < MAX_KTXT_LEN) + memcpy(auth.dat, kdata, auth.length); + xfree(kdata); + + if (auth_krb4(user, &auth, &tkt_user)) { + /* Client has successfully authenticated to us. */ + log("Kerberos authentication accepted %s for account " + "%s from %s", tkt_user, user, get_canonical_hostname()); + /* authentication_type = SSH_AUTH_KERBEROS; */ + authenticated = 1; + xfree(tkt_user); + } + else { + log("Kerberos authentication failed for account " + "%s from %s", user, get_canonical_hostname()); + } + } + break; +#endif /* KRB4 */ + + case SSH_CMSG_AUTH_RHOSTS: + if (!options.rhosts_authentication) + { + log("Rhosts authentication disabled."); + break; + } + + /* Rhosts authentication (also uses /etc/hosts.equiv). */ + if (!privileged_port) + { + log("Rhosts authentication not available for connections from unprivileged port."); + break; + } + + /* Get client user name. Note that we just have to trust the client; + this is one reason why rhosts authentication is insecure. + (Another is IP-spoofing on a local network.) */ + { + int dlen; + client_user = packet_get_string(&dlen); + packet_integrity_check(plen, 4 + dlen, type); + } + + /* Try to authenticate using /etc/hosts.equiv and .rhosts. */ + if (auth_rhosts(pw, client_user, options.ignore_rhosts, + options.strict_modes)) + { + /* Authentication accepted. */ + log("Rhosts authentication accepted for %.100s, remote %.100s on %.700s.", + user, client_user, get_canonical_hostname()); + authenticated = 1; + xfree(client_user); + break; + } + log("Rhosts authentication failed for %.100s, remote %.100s.", + user, client_user); + xfree(client_user); + break; + + case SSH_CMSG_AUTH_RHOSTS_RSA: + if (!options.rhosts_rsa_authentication) + { + log("Rhosts with RSA authentication disabled."); + break; + } + + /* Rhosts authentication (also uses /etc/hosts.equiv) with RSA + host authentication. */ + if (!privileged_port) + { + log("Rhosts authentication not available for connections from unprivileged port."); + break; + } + + { + int ulen, elen, nlen; + /* Get client user name. Note that we just have to trust + the client; root on the client machine can claim to be + any user. */ + client_user = packet_get_string(&ulen); + + /* Get the client host key. */ + client_host_key_e = BN_new(); + client_host_key_n = BN_new(); + client_host_key_bits = packet_get_int(); + packet_get_bignum(client_host_key_e, &elen); + packet_get_bignum(client_host_key_n, &nlen); + + packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type); + } + + /* Try to authenticate using /etc/hosts.equiv and .rhosts. */ + if (auth_rhosts_rsa(pw, client_user, + client_host_key_bits, client_host_key_e, + client_host_key_n, options.ignore_rhosts, + options.strict_modes)) + { + /* Authentication accepted. */ + authenticated = 1; + xfree(client_user); + BN_clear_free(client_host_key_e); + BN_clear_free(client_host_key_n); + break; + } + log("Rhosts authentication failed for %.100s, remote %.100s.", + user, client_user); + xfree(client_user); + BN_clear_free(client_host_key_e); + BN_clear_free(client_host_key_n); + break; + + case SSH_CMSG_AUTH_RSA: + if (!options.rsa_authentication) + { + log("RSA authentication disabled."); + break; + } + + /* RSA authentication requested. */ + { + int nlen; + BIGNUM *n; + n = BN_new(); + packet_get_bignum(n, &nlen); + + packet_integrity_check(plen, nlen, type); + + if (auth_rsa(pw, n, options.strict_modes)) + { + /* Successful authentication. */ + BN_clear_free(n); + log("RSA authentication for %.100s accepted.", user); + authenticated = 1; + break; + } + BN_clear_free(n); + log("RSA authentication for %.100s failed.", user); + } + break; + + case SSH_CMSG_AUTH_PASSWORD: + if (!options.password_authentication) + { + log("Password authentication disabled."); + break; + } + + /* Password authentication requested. */ + /* Read user password. It is in plain text, but was transmitted + over the encrypted channel so it is not visible to an outside + observer. */ + { + int passw_len; + password = packet_get_string(&passw_len); + packet_integrity_check(plen, 4 + passw_len, type); + } + + /* Try authentication with the password. */ + if (auth_password(pw, password)) + { + /* Successful authentication. */ + /* Clear the password from memory. */ + memset(password, 0, strlen(password)); + xfree(password); + log("Password authentication for %.100s accepted.", user); + authenticated = 1; + break; + } + log("Password authentication for %.100s failed.", user); + memset(password, 0, strlen(password)); + xfree(password); + break; + + case SSH_CMSG_AUTH_TIS: + /* TIS Authentication is unsupported */ + log("TIS authentication disabled."); + break; + + default: + /* Any unknown messages will be ignored (and failure returned) + during authentication. */ + log("Unknown message during authentication: type %d", type); + break; /* Respond with a failure message. */ + } + /* If successfully authenticated, break out of loop. */ + if (authenticated) + break; + + /* Send a message indicating that the authentication attempt failed. */ + packet_start(SSH_SMSG_FAILURE); + packet_send(); + packet_write_wait(); + + if (++authentication_failures >= MAX_AUTH_FAILURES) { + packet_disconnect("Too many authentication failures for %.100s from %.200s", + pw->pw_name, get_canonical_hostname()); + } + } + + /* Check if the user is logging in as root and root logins are disallowed. */ + if (pw->pw_uid == 0 && !options.permit_root_login) + { + if (forced_command) + log("Root login accepted for forced command.", forced_command); + else + packet_disconnect("ROOT LOGIN REFUSED FROM %.200s", + get_canonical_hostname()); + } + + /* The user has been authenticated and accepted. */ + packet_start(SSH_SMSG_SUCCESS); + packet_send(); + packet_write_wait(); + + /* Perform session preparation. */ + do_authenticated(pw); +} + +/* Prepares for an interactive session. This is called after the user has + been successfully authenticated. During this message exchange, pseudo + terminals are allocated, X11, TCP/IP, and authentication agent forwardings + are requested, etc. */ + +void do_authenticated(struct passwd *pw) +{ + int type; + int compression_level = 0, enable_compression_after_reply = 0; + int have_pty = 0, ptyfd = -1, ttyfd = -1, xauthfd = -1; + int row, col, xpixel, ypixel, screen; + char ttyname[64]; + char *command, *term = NULL, *display = NULL, *proto = NULL, *data = NULL; + struct group *grp; + gid_t tty_gid; + mode_t tty_mode; + int n_bytes; + + /* Cancel the alarm we set to limit the time taken for authentication. */ + alarm(0); + + /* Inform the channel mechanism that we are the server side and that + the client may request to connect to any port at all. (The user could + do it anyway, and we wouldn\'t know what is permitted except by the + client telling us, so we can equally well trust the client not to request + anything bogus.) */ + channel_permit_all_opens(); + + /* We stay in this loop until the client requests to execute a shell or a + command. */ + while (1) + { + int plen, dlen; + + /* Get a packet from the client. */ + type = packet_read(&plen); + + /* Process the packet. */ + switch (type) + { + case SSH_CMSG_REQUEST_COMPRESSION: + packet_integrity_check(plen, 4, type); + compression_level = packet_get_int(); + if (compression_level < 1 || compression_level > 9) + { + packet_send_debug("Received illegal compression level %d.", + compression_level); + goto fail; + } + /* Enable compression after we have responded with SUCCESS. */ + enable_compression_after_reply = 1; + break; + + case SSH_CMSG_REQUEST_PTY: + if (no_pty_flag) + { + debug("Allocating a pty not permitted for this authentication."); + goto fail; + } + if (have_pty) + packet_disconnect("Protocol error: you already have a pty."); + + debug("Allocating pty."); + + /* Allocate a pty and open it. */ + if (!pty_allocate(&ptyfd, &ttyfd, ttyname)) + { + error("Failed to allocate pty."); + goto fail; + } + + /* Determine the group to make the owner of the tty. */ + grp = getgrnam("tty"); + if (grp) + { + tty_gid = grp->gr_gid; + tty_mode = S_IRUSR|S_IWUSR|S_IWGRP; + } + else + { + tty_gid = pw->pw_gid; + tty_mode = S_IRUSR|S_IWUSR|S_IWGRP|S_IWOTH; + } + + /* Change ownership of the tty. */ + if (chown(ttyname, pw->pw_uid, tty_gid) < 0) + fatal("chown(%.100s, %d, %d) failed: %.100s", + ttyname, pw->pw_uid, tty_gid, strerror(errno)); + if (chmod(ttyname, tty_mode) < 0) + fatal("chmod(%.100s, 0%o) failed: %.100s", + ttyname, tty_mode, strerror(errno)); + + /* Get TERM from the packet. Note that the value may be of arbitrary + length. */ + + term = packet_get_string(&dlen); + packet_integrity_check(dlen, strlen(term), type); + /* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */ + /* Remaining bytes */ + n_bytes = plen - (4 + dlen + 4*4); + + if (strcmp(term, "") == 0) + term = NULL; + + /* Get window size from the packet. */ + row = packet_get_int(); + col = packet_get_int(); + xpixel = packet_get_int(); + ypixel = packet_get_int(); + pty_change_window_size(ptyfd, row, col, xpixel, ypixel); + + /* Get tty modes from the packet. */ + tty_parse_modes(ttyfd, &n_bytes); + packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); + + /* Indicate that we now have a pty. */ + have_pty = 1; + break; + + case SSH_CMSG_X11_REQUEST_FORWARDING: + if (!options.x11_forwarding) + { + packet_send_debug("X11 forwarding disabled in server configuration file."); + goto fail; + } +#ifdef XAUTH_PATH + if (no_x11_forwarding_flag) + { + packet_send_debug("X11 forwarding not permitted for this authentication."); + goto fail; + } + debug("Received request for X11 forwarding with auth spoofing."); + if (display) + packet_disconnect("Protocol error: X11 display already set."); + { + int proto_len, data_len; + proto = packet_get_string(&proto_len); + data = packet_get_string(&data_len); + packet_integrity_check(plen, 4+proto_len + 4+data_len + 4, type); + } + if (packet_get_protocol_flags() & SSH_PROTOFLAG_SCREEN_NUMBER) + screen = packet_get_int(); + else + screen = 0; + display = x11_create_display_inet(screen); + if (!display) + goto fail; + + /* Setup to always have a local .Xauthority. */ + xauthfile = xmalloc(MAXPATHLEN); + snprintf(xauthfile, MAXPATHLEN, "/tmp/XauthXXXXXX"); + + if ((xauthfd = mkstemp(xauthfile)) != -1) { + fchown(xauthfd, pw->pw_uid, pw->pw_gid); + close(xauthfd); + } + else { + xfree(xauthfile); + xauthfile = NULL; + } + break; +#else /* XAUTH_PATH */ + /* No xauth program; we won't accept forwarding with spoofing. */ + packet_send_debug("No xauth program; cannot forward with spoofing."); + goto fail; +#endif /* XAUTH_PATH */ + + case SSH_CMSG_AGENT_REQUEST_FORWARDING: + if (no_agent_forwarding_flag) + { + debug("Authentication agent forwarding not permitted for this authentication."); + goto fail; + } + debug("Received authentication agent forwarding request."); + auth_input_request_forwarding(pw); + break; + + case SSH_CMSG_PORT_FORWARD_REQUEST: + if (no_port_forwarding_flag) + { + debug("Port forwarding not permitted for this authentication."); + goto fail; + } + debug("Received TCP/IP port forwarding request."); + channel_input_port_forward_request(pw->pw_uid == 0); + break; + + case SSH_CMSG_EXEC_SHELL: + /* Set interactive/non-interactive mode. */ + packet_set_interactive(have_pty || display != NULL, + options.keepalives); + + if (forced_command != NULL) + goto do_forced_command; + debug("Forking shell."); + packet_integrity_check(plen, 0, type); + if (have_pty) + do_exec_pty(NULL, ptyfd, ttyfd, ttyname, pw, term, display, proto, + data); + else + do_exec_no_pty(NULL, pw, display, proto, data); + return; + + case SSH_CMSG_EXEC_CMD: + /* Set interactive/non-interactive mode. */ + packet_set_interactive(have_pty || display != NULL, + options.keepalives); + + if (forced_command != NULL) + goto do_forced_command; + /* Get command from the packet. */ + { + int dlen; + command = packet_get_string(&dlen); + debug("Executing command '%.500s'", command); + packet_integrity_check(plen, 4 + dlen, type); + } + if (have_pty) + do_exec_pty(command, ptyfd, ttyfd, ttyname, pw, term, display, + proto, data); + else + do_exec_no_pty(command, pw, display, proto, data); + xfree(command); + return; + + case SSH_CMSG_MAX_PACKET_SIZE: + debug("The server does not support limiting packet size."); + goto fail; + + default: + /* Any unknown messages in this phase are ignored, and a failure + message is returned. */ + log("Unknown packet type received after authentication: %d", type); + goto fail; + } + + /* The request was successfully processed. */ + packet_start(SSH_SMSG_SUCCESS); + packet_send(); + packet_write_wait(); + + /* Enable compression now that we have replied if appropriate. */ + if (enable_compression_after_reply) + { + enable_compression_after_reply = 0; + packet_start_compression(compression_level); + } + + continue; + + fail: + /* The request failed. */ + packet_start(SSH_SMSG_FAILURE); + packet_send(); + packet_write_wait(); + continue; + + do_forced_command: + /* There is a forced command specified for this login. Execute it. */ + debug("Executing forced command: %.900s", forced_command); + if (have_pty) + do_exec_pty(forced_command, ptyfd, ttyfd, ttyname, pw, term, display, + proto, data); + else + do_exec_no_pty(forced_command, pw, display, proto, data); + return; + } +} + +/* This is called to fork and execute a command when we have no tty. This + will call do_child from the child, and server_loop from the parent after + setting up file descriptors and such. */ + +void do_exec_no_pty(const char *command, struct passwd *pw, + const char *display, const char *auth_proto, + const char *auth_data) +{ + int pid; + +#ifdef USE_PIPES + int pin[2], pout[2], perr[2]; + /* Allocate pipes for communicating with the program. */ + if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0) + packet_disconnect("Could not create pipes: %.100s", + strerror(errno)); +#else /* USE_PIPES */ + int inout[2], err[2]; + /* Uses socket pairs to communicate with the program. */ + if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 || + socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) + packet_disconnect("Could not create socket pairs: %.100s", + strerror(errno)); +#endif /* USE_PIPES */ + + setproctitle("%s@notty", pw->pw_name); + + /* Fork the child. */ + if ((pid = fork()) == 0) + { + /* Child. Reinitialize the log since the pid has changed. */ + log_init(av0, debug_flag && !inetd_flag, debug_flag, + options.quiet_mode, options.log_facility); + + /* Create a new session and process group since the 4.4BSD setlogin() + affects the entire process group. */ + if (setsid() < 0) + error("setsid failed: %.100s", strerror(errno)); + +#ifdef USE_PIPES + /* Redirect stdin. We close the parent side of the socket pair, + and make the child side the standard input. */ + close(pin[1]); + if (dup2(pin[0], 0) < 0) + perror("dup2 stdin"); + close(pin[0]); + + /* Redirect stdout. */ + close(pout[0]); + if (dup2(pout[1], 1) < 0) + perror("dup2 stdout"); + close(pout[1]); + + /* Redirect stderr. */ + close(perr[0]); + if (dup2(perr[1], 2) < 0) + perror("dup2 stderr"); + close(perr[1]); +#else /* USE_PIPES */ + /* Redirect stdin, stdout, and stderr. Stdin and stdout will use the + same socket, as some programs (particularly rdist) seem to depend + on it. */ + close(inout[1]); + close(err[1]); + if (dup2(inout[0], 0) < 0) /* stdin */ + perror("dup2 stdin"); + if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */ + perror("dup2 stdout"); + if (dup2(err[0], 2) < 0) /* stderr */ + perror("dup2 stderr"); +#endif /* USE_PIPES */ + + /* Do processing for the child (exec command etc). */ + do_child(command, pw, NULL, display, auth_proto, auth_data, NULL); + /*NOTREACHED*/ + } + if (pid < 0) + packet_disconnect("fork failed: %.100s", strerror(errno)); +#ifdef USE_PIPES + /* We are the parent. Close the child sides of the pipes. */ + close(pin[0]); + close(pout[1]); + close(perr[1]); + + /* Enter the interactive session. */ + server_loop(pid, pin[1], pout[0], perr[0]); + /* server_loop has closed pin[1], pout[1], and perr[1]. */ +#else /* USE_PIPES */ + /* We are the parent. Close the child sides of the socket pairs. */ + close(inout[0]); + close(err[0]); + + /* Enter the interactive session. Note: server_loop must be able to handle + the case that fdin and fdout are the same. */ + server_loop(pid, inout[1], inout[1], err[1]); + /* server_loop has closed inout[1] and err[1]. */ +#endif /* USE_PIPES */ +} + +struct pty_cleanup_context +{ + const char *ttyname; + int pid; +}; + +/* Function to perform cleanup if we get aborted abnormally (e.g., due to a + dropped connection). */ + +void pty_cleanup_proc(void *context) +{ + struct pty_cleanup_context *cu = context; + + debug("pty_cleanup_proc called"); + +#if defined(KRB4) + /* Destroy user's ticket cache file. */ + (void) dest_tkt(); +#endif /* KRB4 */ + + /* Record that the user has logged out. */ + record_logout(cu->pid, cu->ttyname); + + /* Release the pseudo-tty. */ + pty_release(cu->ttyname); +} + +/* This is called to fork and execute a command when we have a tty. This + will call do_child from the child, and server_loop from the parent after + setting up file descriptors, controlling tty, updating wtmp, utmp, + lastlog, and other such operations. */ + +void do_exec_pty(const char *command, int ptyfd, int ttyfd, + const char *ttyname, struct passwd *pw, const char *term, + const char *display, const char *auth_proto, + const char *auth_data) +{ + int pid, fdout; + const char *hostname; + time_t last_login_time; + char buf[100], *time_string; + FILE *f; + char line[256]; + struct stat st; + int quiet_login; + struct sockaddr_in from; + int fromlen; + struct pty_cleanup_context cleanup_context; + + /* Get remote host name. */ + hostname = get_canonical_hostname(); + + /* Get the time when the user last logged in. Buf will be set to contain + the hostname the last login was from. */ + if(!options.use_login) { + last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name, + buf, sizeof(buf)); + } + + setproctitle("%s@%s", pw->pw_name, strrchr(ttyname, '/') + 1); + + /* Fork the child. */ + if ((pid = fork()) == 0) + { + pid = getpid(); + + /* Child. Reinitialize the log because the pid has changed. */ + log_init(av0, debug_flag && !inetd_flag, debug_flag, options.quiet_mode, + options.log_facility); + + /* Close the master side of the pseudo tty. */ + close(ptyfd); + + /* Make the pseudo tty our controlling tty. */ + pty_make_controlling_tty(&ttyfd, ttyname); + + /* Redirect stdin from the pseudo tty. */ + if (dup2(ttyfd, fileno(stdin)) < 0) + error("dup2 stdin failed: %.100s", strerror(errno)); + + /* Redirect stdout to the pseudo tty. */ + if (dup2(ttyfd, fileno(stdout)) < 0) + error("dup2 stdin failed: %.100s", strerror(errno)); + + /* Redirect stderr to the pseudo tty. */ + if (dup2(ttyfd, fileno(stderr)) < 0) + error("dup2 stdin failed: %.100s", strerror(errno)); + + /* Close the extra descriptor for the pseudo tty. */ + close(ttyfd); + + /* Get IP address of client. This is needed because we want to record + where the user logged in from. If the connection is not a socket, + let the ip address be 0.0.0.0. */ + memset(&from, 0, sizeof(from)); + if (packet_get_connection_in() == packet_get_connection_out()) + { + fromlen = sizeof(from); + if (getpeername(packet_get_connection_in(), + (struct sockaddr *)&from, &fromlen) < 0) + fatal("getpeername: %.100s", strerror(errno)); + } + + /* Record that there was a login on that terminal. */ + record_login(pid, ttyname, pw->pw_name, pw->pw_uid, hostname, + &from); + + /* Check if .hushlogin exists. */ + snprintf(line, sizeof line, "%.200s/.hushlogin", pw->pw_dir); + quiet_login = stat(line, &st) >= 0; + + /* If the user has logged in before, display the time of last login. + However, don't display anything extra if a command has been + specified (so that ssh can be used to execute commands on a remote + machine without users knowing they are going to another machine). + Login(1) will do this for us as well, so check if login(1) is used */ + if (command == NULL && last_login_time != 0 && !quiet_login && + !options.use_login) + { + /* Convert the date to a string. */ + time_string = ctime(&last_login_time); + /* Remove the trailing newline. */ + if (strchr(time_string, '\n')) + *strchr(time_string, '\n') = 0; + /* Display the last login time. Host if displayed if known. */ + if (strcmp(buf, "") == 0) + printf("Last login: %s\r\n", time_string); + else + printf("Last login: %s from %s\r\n", time_string, buf); + } + + /* Print /etc/motd unless a command was specified or printing it was + disabled in server options or login(1) will be used. Note that + some machines appear to print it in /etc/profile or similar. */ + if (command == NULL && options.print_motd && !quiet_login && + !options.use_login) + { + /* Print /etc/motd if it exists. */ + f = fopen("/etc/motd", "r"); + if (f) + { + while (fgets(line, sizeof(line), f)) + fputs(line, stdout); + fclose(f); + } + } + + /* Do common processing for the child, such as execing the command. */ + do_child(command, pw, term, display, auth_proto, auth_data, ttyname); + /*NOTREACHED*/ + } + if (pid < 0) + packet_disconnect("fork failed: %.100s", strerror(errno)); + /* Parent. Close the slave side of the pseudo tty. */ + close(ttyfd); + + /* Create another descriptor of the pty master side for use as the standard + input. We could use the original descriptor, but this simplifies code + in server_loop. The descriptor is bidirectional. */ + fdout = dup(ptyfd); + if (fdout < 0) + packet_disconnect("dup failed: %.100s", strerror(errno)); + + /* Add a cleanup function to clear the utmp entry and record logout time + in case we call fatal() (e.g., the connection gets closed). */ + cleanup_context.pid = pid; + cleanup_context.ttyname = ttyname; + fatal_add_cleanup(pty_cleanup_proc, (void *)&cleanup_context); + + /* Enter interactive session. */ + server_loop(pid, ptyfd, fdout, -1); + /* server_loop has not closed ptyfd and fdout. */ + + /* Cancel the cleanup function. */ + fatal_remove_cleanup(pty_cleanup_proc, (void *)&cleanup_context); + + /* Record that the user has logged out. */ + record_logout(pid, ttyname); + + /* Release the pseudo-tty. */ + pty_release(ttyname); + + /* Close the server side of the socket pairs. We must do this after the + pty cleanup, so that another process doesn't get this pty while we're + still cleaning up. */ + close(ptyfd); + close(fdout); +} + +/* Sets the value of the given variable in the environment. If the variable + already exists, its value is overriden. */ + +void child_set_env(char ***envp, unsigned int *envsizep, const char *name, + const char *value) +{ + unsigned int i, namelen; + char **env; + + /* Find the slot where the value should be stored. If the variable already + exists, we reuse the slot; otherwise we append a new slot at the end + of the array, expanding if necessary. */ + env = *envp; + namelen = strlen(name); + for (i = 0; env[i]; i++) + if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') + break; + if (env[i]) + { + /* Name already exists. Reuse the slot. */ + xfree(env[i]); + } + else + { + /* New variable. Expand the array if necessary. */ + if (i >= (*envsizep) - 1) + { + (*envsizep) += 50; + env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *)); + } + + /* Need to set the NULL pointer at end of array beyond the new + slot. */ + env[i + 1] = NULL; + } + + /* Allocate space and format the variable in the appropriate slot. */ + env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); + snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); +} + +/* Reads environment variables from the given file and adds/overrides them + into the environment. If the file does not exist, this does nothing. + Otherwise, it must consist of empty lines, comments (line starts with '#') + and assignments of the form name=value. No other forms are allowed. */ + +void read_environment_file(char ***env, unsigned int *envsize, + const char *filename) +{ + FILE *f; + char buf[4096]; + char *cp, *value; + + /* Open the environment file. */ + f = fopen(filename, "r"); + if (!f) + return; /* Not found. */ + + /* Process each line. */ + while (fgets(buf, sizeof(buf), f)) + { + /* Skip leading whitespace. */ + for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) + ; + + /* Ignore empty and comment lines. */ + if (!*cp || *cp == '#' || *cp == '\n') + continue; + + /* Remove newline. */ + if (strchr(cp, '\n')) + *strchr(cp, '\n') = '\0'; + + /* Find the equals sign. Its lack indicates badly formatted line. */ + value = strchr(cp, '='); + if (value == NULL) + { + fprintf(stderr, "Bad line in %.100s: %.200s\n", filename, buf); + continue; + } + + /* Replace the equals sign by nul, and advance value to the value + string. */ + *value = '\0'; + value++; + + /* Set the value in environment. */ + child_set_env(env, envsize, cp, value); + } + + fclose(f); +} + +/* Performs common processing for the child, such as setting up the + environment, closing extra file descriptors, setting the user and group + ids, and executing the command or shell. */ + +void do_child(const char *command, struct passwd *pw, const char *term, + const char *display, const char *auth_proto, + const char *auth_data, const char *ttyname) +{ + const char *shell, *cp = NULL; + char buf[256]; + FILE *f; + unsigned int envsize, i; + char **env; + extern char **environ; + struct stat st; + char *argv[10]; + + /* Check /etc/nologin. */ + f = fopen("/etc/nologin", "r"); + if (f) + { /* /etc/nologin exists. Print its contents and exit. */ + while (fgets(buf, sizeof(buf), f)) + fputs(buf, stderr); + fclose(f); + if (pw->pw_uid != 0) + exit(254); + } + + /* Set login name in the kernel. */ + if (setlogin(pw->pw_name) < 0) + error("setlogin failed: %s", strerror(errno)); + + /* Set uid, gid, and groups. */ + /* Login(1) does this as well, and it needs uid 0 for the "-h" switch, + so we let login(1) to this for us. */ + if(!options.use_login) { + if (getuid() == 0 || geteuid() == 0) + { + if (setgid(pw->pw_gid) < 0) + { + perror("setgid"); + exit(1); + } + /* Initialize the group list. */ + if (initgroups(pw->pw_name, pw->pw_gid) < 0) + { + perror("initgroups"); + exit(1); + } + endgrent(); + + /* Permanently switch to the desired uid. */ + permanently_set_uid(pw->pw_uid); + } + + if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) + fatal("Failed to set uids to %d.", (int)pw->pw_uid); + } + + /* Get the shell from the password data. An empty shell field is legal, + and means /bin/sh. */ + shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; + +#ifdef AFS + /* Try to get AFS tokens for the local cell. */ + if (k_hasafs()) { + char cell[64]; + + if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) + krb_afslog(cell, 0); + + krb_afslog(0, 0); + } +#endif /* AFS */ + + /* Initialize the environment. In the first part we allocate space for + all environment variables. */ + envsize = 100; + env = xmalloc(envsize * sizeof(char *)); + env[0] = NULL; + + if(!options.use_login) { + /* Set basic environment. */ + child_set_env(&env, &envsize, "USER", pw->pw_name); + child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); + child_set_env(&env, &envsize, "HOME", pw->pw_dir); + child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); + + snprintf(buf, sizeof buf, "%.200s/%.50s", + _PATH_MAILDIR, pw->pw_name); + child_set_env(&env, &envsize, "MAIL", buf); + + /* Normal systems set SHELL by default. */ + child_set_env(&env, &envsize, "SHELL", shell); + } + + /* Let it inherit timezone if we have one. */ + if (getenv("TZ")) + child_set_env(&env, &envsize, "TZ", getenv("TZ")); + + /* Set custom environment options from RSA authentication. */ + while (custom_environment) + { + struct envstring *ce = custom_environment; + char *s = ce->s; + int i; + for (i = 0; s[i] != '=' && s[i]; i++) + ; + if (s[i] == '=') + { + s[i] = 0; + child_set_env(&env, &envsize, s, s + i + 1); + } + custom_environment = ce->next; + xfree(ce->s); + xfree(ce); + } + + /* Set SSH_CLIENT. */ + snprintf(buf, sizeof buf, "%.50s %d %d", + get_remote_ipaddr(), get_remote_port(), options.port); + child_set_env(&env, &envsize, "SSH_CLIENT", buf); + + /* Set SSH_TTY if we have a pty. */ + if (ttyname) + child_set_env(&env, &envsize, "SSH_TTY", ttyname); + + /* Set TERM if we have a pty. */ + if (term) + child_set_env(&env, &envsize, "TERM", term); + + /* Set DISPLAY if we have one. */ + if (display) + child_set_env(&env, &envsize, "DISPLAY", display); + +#ifdef KRB4 + if (ticket) + child_set_env(&env, &envsize, "KRBTKFILE", ticket); +#endif /* KRB4 */ + + /* Set XAUTHORITY to always be a local file. */ + if (xauthfile) + child_set_env(&env, &envsize, "XAUTHORITY", xauthfile); + + /* Set variable for forwarded authentication connection, if we have one. */ + if (auth_get_socket_name() != NULL) + child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, + auth_get_socket_name()); + + /* Read $HOME/.ssh/environment. */ + if(!options.use_login) { + snprintf(buf, sizeof buf, "%.200s/.ssh/environment", pw->pw_dir); + read_environment_file(&env, &envsize, buf); + } + + /* If debugging, dump the environment to stderr. */ + if (debug_flag) + { + fprintf(stderr, "Environment:\n"); + for (i = 0; env[i]; i++) + fprintf(stderr, " %.200s\n", env[i]); + } + + /* Close the connection descriptors; note that this is the child, and the + server will still have the socket open, and it is important that we + do not shutdown it. Note that the descriptors cannot be closed before + building the environment, as we call get_remote_ipaddr there. */ + if (packet_get_connection_in() == packet_get_connection_out()) + close(packet_get_connection_in()); + else + { + close(packet_get_connection_in()); + close(packet_get_connection_out()); + } + /* Close all descriptors related to channels. They will still remain + open in the parent. */ + channel_close_all(); + + /* Close any extra file descriptors. Note that there may still be + descriptors left by system functions. They will be closed later. */ + endpwent(); + endhostent(); + + /* Close any extra open file descriptors so that we don\'t have them + hanging around in clients. Note that we want to do this after + initgroups, because at least on Solaris 2.3 it leaves file descriptors + open. */ + for (i = 3; i < 64; i++) + close(i); + + /* Change current directory to the user\'s home directory. */ + if (chdir(pw->pw_dir) < 0) + fprintf(stderr, "Could not chdir to home directory %s: %s\n", + pw->pw_dir, strerror(errno)); + + /* Must take new environment into use so that .ssh/rc, /etc/sshrc and + xauth are run in the proper environment. */ + environ = env; + + /* Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found first + in this order). */ + if(!options.use_login) { + if (stat(SSH_USER_RC, &st) >= 0) + { + if (debug_flag) + fprintf(stderr, "Running /bin/sh %s\n", SSH_USER_RC); + + f = popen("/bin/sh " SSH_USER_RC, "w"); + if (f) + { + if (auth_proto != NULL && auth_data != NULL) + fprintf(f, "%s %s\n", auth_proto, auth_data); + pclose(f); + } + else + fprintf(stderr, "Could not run %s\n", SSH_USER_RC); + } + else + if (stat(SSH_SYSTEM_RC, &st) >= 0) + { + if (debug_flag) + fprintf(stderr, "Running /bin/sh %s\n", SSH_SYSTEM_RC); + + f = popen("/bin/sh " SSH_SYSTEM_RC, "w"); + if (f) + { + if (auth_proto != NULL && auth_data != NULL) + fprintf(f, "%s %s\n", auth_proto, auth_data); + pclose(f); + } + else + fprintf(stderr, "Could not run %s\n", SSH_SYSTEM_RC); + } +#ifdef XAUTH_PATH + else + { + /* Add authority data to .Xauthority if appropriate. */ + if (auth_proto != NULL && auth_data != NULL) + { + if (debug_flag) + fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n", + XAUTH_PATH, display, auth_proto, auth_data); + + f = popen(XAUTH_PATH " -q -", "w"); + if (f) + { + fprintf(f, "add %s %s %s\n", display, auth_proto, auth_data); + fclose(f); + } + else + fprintf(stderr, "Could not run %s -q -\n", XAUTH_PATH); + } + } +#endif /* XAUTH_PATH */ + + /* Get the last component of the shell name. */ + cp = strrchr(shell, '/'); + if (cp) + cp++; + else + cp = shell; + } + + /* If we have no command, execute the shell. In this case, the shell name + to be passed in argv[0] is preceded by '-' to indicate that this is + a login shell. */ + if (!command) + { + if(!options.use_login) { + char buf[256]; + + /* Check for mail if we have a tty and it was enabled in server options. */ + if (ttyname && options.check_mail) { + char *mailbox; + struct stat mailstat; + mailbox = getenv("MAIL"); + if(mailbox != NULL) { + if(stat(mailbox, &mailstat) != 0 || mailstat.st_size == 0) { + printf("No mail.\n"); + } else if(mailstat.st_mtime < mailstat.st_atime) { + printf("You have mail.\n"); + } else { + printf("You have new mail.\n"); + } + } + } + /* Start the shell. Set initial character to '-'. */ + buf[0] = '-'; + strncpy(buf + 1, cp, sizeof(buf) - 1); + buf[sizeof(buf) - 1] = 0; + /* Execute the shell. */ + argv[0] = buf; + argv[1] = NULL; + execve(shell, argv, env); + /* Executing the shell failed. */ + perror(shell); + exit(1); + + } else { + /* Launch login(1). */ + + execl("/usr/bin/login", "login", "-h", get_remote_ipaddr(), "-p", "-f", "--", pw->pw_name, NULL); + + /* Login couldn't be executed, die. */ + + perror("login"); + exit(1); + } + } + + /* Execute the command using the user's shell. This uses the -c option + to execute the command. */ + argv[0] = (char *)cp; + argv[1] = "-c"; + argv[2] = (char *)command; + argv[3] = NULL; + execve(shell, argv, env); + perror(shell); + exit(1); +} diff --git a/sshd.init b/sshd.init new file mode 100755 index 00000000..b36b57aa --- /dev/null +++ b/sshd.init @@ -0,0 +1,49 @@ +#!/bin/bash + +# Init file for OpenSSH sshd +# +# chkconfig: 2345 55 25 +# description: OpenSSH server daemon +# +# processname: sshd +# config: /etc/ssh/ssh_host_key +# config: /etc/ssh/ssh_host_key.pub +# config: /etc/ssh/ssh_random_seed +# config: /etc/ssh/sshd_config +# pidfile: /var/run/sshd.pid + +# source function library +. /etc/rc.d/init.d/functions + +RETVAL=0 + +case "$1" in + start) + echo -n "Starting sshd: " + daemon /usr/sbin/sshd + RETVAL=$? + [ $RETVAL -eq 0 ] && touch /var/lock/subsys/sshd + echo + ;; + stop) + echo -n "Shutting down sshd: " + killproc sshd + RETVAL=$? + [ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/sshd + echo + ;; + restart) + $0 stop + $0 start + RETVAL=$? + ;; + status) + status sshd + RETVAL=$? + ;; + *) + echo "Usage: sshd {start|stop|restart|status}" + exit 1 +esac + +exit $RETVAL diff --git a/sshd_config b/sshd_config new file mode 100644 index 00000000..97f6f8e1 --- /dev/null +++ b/sshd_config @@ -0,0 +1,44 @@ +# This is ssh server systemwide configuration file. + +Port 22 +ListenAddress 0.0.0.0 +HostKey /etc/ssh/ssh_host_key +ServerKeyBits 768 +LoginGraceTime 600 +KeyRegenerationInterval 3600 +PermitRootLogin yes +# +# Don't read ~/.rhosts and ~/.shosts files +IgnoreRhosts yes +StrictModes yes +QuietMode no +X11Forwarding yes +X11DisplayOffset 10 +FascistLogging no +PrintMotd yes +KeepAlive yes +SyslogFacility AUTH +RhostsAuthentication no +# +# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts +RhostsRSAAuthentication no +# +RSAAuthentication yes + +# To disable tunneled clear text passwords, change to no here! +PasswordAuthentication yes +PermitEmptyPasswords no +# Uncomment to disable s/key passwords +#SkeyAuthentication no + +# To change Kerberos options +#KerberosAuthentication no +#KerberosOrLocalPasswd yes +#AFSTokenPassing no +#KerberosTicketCleanup no + +# Kerberos TGT Passing does only work with the AFS kaserver +#KerberosTgtPassing yes + +#CheckMail yes +#UseLogin no diff --git a/strlcpy.c b/strlcpy.c new file mode 100644 index 00000000..300a28bc --- /dev/null +++ b/strlcpy.c @@ -0,0 +1,68 @@ +/* $OpenBSD: strlcpy.c,v 1.4 1999/05/01 18:56:41 millert Exp $ */ + +/* + * Copyright (c) 1998 Todd C. Miller + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, + * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY + * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL + * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; + * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR + * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF + * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#if defined(LIBC_SCCS) && !defined(lint) +static char *rcsid = "$OpenBSD: strlcpy.c,v 1.4 1999/05/01 18:56:41 millert Exp $"; +#endif /* LIBC_SCCS and not lint */ + +#include +#include + +/* + * Copy src to string dst of size siz. At most siz-1 characters + * will be copied. Always NUL terminates (unless siz == 0). + * Returns strlen(src); if retval >= siz, truncation occurred. + */ +size_t strlcpy(dst, src, siz) + char *dst; + const char *src; + size_t siz; +{ + register char *d = dst; + register const char *s = src; + register size_t n = siz; + + /* Copy as many bytes as will fit */ + if (n != 0 && --n != 0) { + do { + if ((*d++ = *s++) == 0) + break; + } while (--n != 0); + } + + /* Not enough room in dst, add NUL and traverse rest of src */ + if (n == 0) { + if (siz != 0) + *d = '\0'; /* NUL-terminate dst */ + while (*s++) + ; + } + + return(s - src - 1); /* count does not include NUL */ +} diff --git a/strlcpy.h b/strlcpy.h new file mode 100644 index 00000000..824df300 --- /dev/null +++ b/strlcpy.h @@ -0,0 +1,4 @@ +#ifndef _STRLCPY_H +#define _STRLCPY_H +size_t strlcpy(char *dst, const char *src, size_t siz); +#endif /* _STRLCPY_H */ diff --git a/tildexpand.c b/tildexpand.c new file mode 100644 index 00000000..32266674 --- /dev/null +++ b/tildexpand.c @@ -0,0 +1,70 @@ +/* + +tildexpand.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Wed Jul 12 01:07:36 1995 ylo + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "xmalloc.h" +#include "ssh.h" + +/* Expands tildes in the file name. Returns data allocated by xmalloc. + Warning: this calls getpw*. */ + +char *tilde_expand_filename(const char *filename, uid_t my_uid) +{ + const char *cp; + unsigned int userlen; + char *expanded; + struct passwd *pw; + char user[100]; + + /* Return immediately if no tilde. */ + if (filename[0] != '~') + return xstrdup(filename); + + /* Skip the tilde. */ + filename++; + + /* Find where the username ends. */ + cp = strchr(filename, '/'); + if (cp) + userlen = cp - filename; /* Have something after username. */ + else + userlen = strlen(filename); /* Nothign after username. */ + if (userlen == 0) + pw = getpwuid(my_uid); /* Own home directory. */ + else + { + /* Tilde refers to someone elses home directory. */ + if (userlen > sizeof(user) - 1) + fatal("User name after tilde too long."); + memcpy(user, filename, userlen); + user[userlen] = 0; + pw = getpwnam(user); + } + + /* Check that we found the user. */ + if (!pw) + fatal("Unknown user %100s.", user); + + /* If referring to someones home directory, return it now. */ + if (!cp) + { /* Only home directory specified */ + return xstrdup(pw->pw_dir); + } + + /* Build a path combining the specified directory and path. */ + expanded = xmalloc(strlen(pw->pw_dir) + strlen(cp + 1) + 2); + sprintf(expanded, "%s/%s", pw->pw_dir, cp + 1); + return expanded; +} diff --git a/ttymodes.c b/ttymodes.c new file mode 100644 index 00000000..6124620f --- /dev/null +++ b/ttymodes.c @@ -0,0 +1,359 @@ +/* + +ttymodes.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Tue Mar 21 15:59:15 1995 ylo + +Encoding and decoding of terminal modes in a portable way. +Much of the format is defined in ttymodes.h; it is included multiple times +into this file with the appropriate macro definitions to generate the +suitable code. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "packet.h" +#include "ssh.h" + +#define TTY_OP_END 0 +#define TTY_OP_ISPEED 192 /* int follows */ +#define TTY_OP_OSPEED 193 /* int follows */ + +/* Converts POSIX speed_t to a baud rate. The values of the constants + for speed_t are not themselves portable. */ + +static int speed_to_baud(speed_t speed) +{ + switch (speed) + { + case B0: + return 0; + case B50: + return 50; + case B75: + return 75; + case B110: + return 110; + case B134: + return 134; + case B150: + return 150; + case B200: + return 200; + case B300: + return 300; + case B600: + return 600; + case B1200: + return 1200; + case B1800: + return 1800; + case B2400: + return 2400; + case B4800: + return 4800; + case B9600: + return 9600; + +#ifdef B19200 + case B19200: + return 19200; +#else /* B19200 */ +#ifdef EXTA + case EXTA: + return 19200; +#endif /* EXTA */ +#endif /* B19200 */ + +#ifdef B38400 + case B38400: + return 38400; +#else /* B38400 */ +#ifdef EXTB + case EXTB: + return 38400; +#endif /* EXTB */ +#endif /* B38400 */ + +#ifdef B7200 + case B7200: + return 7200; +#endif /* B7200 */ +#ifdef B14400 + case B14400: + return 14400; +#endif /* B14400 */ +#ifdef B28800 + case B28800: + return 28800; +#endif /* B28800 */ +#ifdef B57600 + case B57600: + return 57600; +#endif /* B57600 */ +#ifdef B76800 + case B76800: + return 76800; +#endif /* B76800 */ +#ifdef B115200 + case B115200: + return 115200; +#endif /* B115200 */ +#ifdef B230400 + case B230400: + return 230400; +#endif /* B230400 */ + default: + return 9600; + } +} + +/* Converts a numeric baud rate to a POSIX speed_t. */ + +static speed_t baud_to_speed(int baud) +{ + switch (baud) + { + case 0: + return B0; + case 50: + return B50; + case 75: + return B75; + case 110: + return B110; + case 134: + return B134; + case 150: + return B150; + case 200: + return B200; + case 300: + return B300; + case 600: + return B600; + case 1200: + return B1200; + case 1800: + return B1800; + case 2400: + return B2400; + case 4800: + return B4800; + case 9600: + return B9600; + +#ifdef B19200 + case 19200: + return B19200; +#else /* B19200 */ +#ifdef EXTA + case 19200: + return EXTA; +#endif /* EXTA */ +#endif /* B19200 */ + +#ifdef B38400 + case 38400: + return B38400; +#else /* B38400 */ +#ifdef EXTB + case 38400: + return EXTB; +#endif /* EXTB */ +#endif /* B38400 */ + +#ifdef B7200 + case 7200: + return B7200; +#endif /* B7200 */ +#ifdef B14400 + case 14400: + return B14400; +#endif /* B14400 */ +#ifdef B28800 + case 28800: + return B28800; +#endif /* B28800 */ +#ifdef B57600 + case 57600: + return B57600; +#endif /* B57600 */ +#ifdef B76800 + case 76800: + return B76800; +#endif /* B76800 */ +#ifdef B115200 + case 115200: + return B115200; +#endif /* B115200 */ +#ifdef B230400 + case 230400: + return B230400; +#endif /* B230400 */ + default: + return B9600; + } +} + +/* Encodes terminal modes for the terminal referenced by fd in a portable + manner, and appends the modes to a packet being constructed. */ + +void tty_make_modes(int fd) +{ + struct termios tio; + int baud; + + /* Get the modes. */ + if (tcgetattr(fd, &tio) < 0) + { + packet_put_char(TTY_OP_END); + log("tcgetattr: %.100s", strerror(errno)); + return; + } + + /* Store input and output baud rates. */ + baud = speed_to_baud(cfgetospeed(&tio)); + packet_put_char(TTY_OP_OSPEED); + packet_put_int(baud); + baud = speed_to_baud(cfgetispeed(&tio)); + packet_put_char(TTY_OP_ISPEED); + packet_put_int(baud); + + /* Store values of mode flags. */ +#define TTYCHAR(NAME, OP) \ + packet_put_char(OP); packet_put_char(tio.c_cc[NAME]); +#define TTYMODE(NAME, FIELD, OP) \ + packet_put_char(OP); packet_put_char((tio.FIELD & NAME) != 0); +#define SGTTYCHAR(NAME, OP) +#define SGTTYMODE(NAME, FIELD, OP) +#define SGTTYMODEN(NAME, FIELD, OP) + +#include "ttymodes.h" + +#undef TTYCHAR +#undef TTYMODE +#undef SGTTYCHAR +#undef SGTTYMODE +#undef SGTTYMODEN + + /* Mark end of mode data. */ + packet_put_char(TTY_OP_END); +} + +/* Decodes terminal modes for the terminal referenced by fd in a portable + manner from a packet being read. */ + +void tty_parse_modes(int fd, int *n_bytes_ptr) +{ + struct termios tio; + int opcode, baud; + int n_bytes = 0; + int failure = 0; + + /* Get old attributes for the terminal. We will modify these flags. + I am hoping that if there are any machine-specific modes, they will + initially have reasonable values. */ + if (tcgetattr(fd, &tio) < 0) + failure = -1; + + for (;;) + { + n_bytes += 1; + opcode = packet_get_char(); + switch (opcode) + { + case TTY_OP_END: + goto set; + + case TTY_OP_ISPEED: + n_bytes += 4; + baud = packet_get_int(); + if (failure != -1 && cfsetispeed(&tio, baud_to_speed(baud)) < 0) + error("cfsetispeed failed for %d", baud); + break; + + case TTY_OP_OSPEED: + n_bytes += 4; + baud = packet_get_int(); + if (failure != -1 && cfsetospeed(&tio, baud_to_speed(baud)) < 0) + error("cfsetospeed failed for %d", baud); + break; + +#define TTYCHAR(NAME, OP) \ + case OP: \ + n_bytes += 1; \ + tio.c_cc[NAME] = packet_get_char(); \ + break; +#define TTYMODE(NAME, FIELD, OP) \ + case OP: \ + n_bytes += 1; \ + if (packet_get_char()) \ + tio.FIELD |= NAME; \ + else \ + tio.FIELD &= ~NAME; \ + break; +#define SGTTYCHAR(NAME, OP) +#define SGTTYMODE(NAME, FIELD, OP) +#define SGTTYMODEN(NAME, FIELD, OP) + +#include "ttymodes.h" + +#undef TTYCHAR +#undef TTYMODE +#undef SGTTYCHAR +#undef SGTTYMODE +#undef SGTTYMODEN + + default: + debug("Ignoring unsupported tty mode opcode %d (0x%x)", + opcode, opcode); + /* Opcodes 0 to 127 are defined to have a one-byte argument. */ + if (opcode >= 0 && opcode < 128) + { + n_bytes += 1; + (void)packet_get_char(); + break; + } + else + { + /* Opcodes 128 to 159 are defined to have an integer argument. */ + if (opcode >= 128 && opcode < 160) + { + n_bytes += 4; + (void)packet_get_int(); + break; + } + } + /* It is a truly undefined opcode (160 to 255). We have no idea + about its arguments. So we must stop parsing. Note that some + data may be left in the packet; hopefully there is nothing more + coming after the mode data. */ + log("parse_tty_modes: unknown opcode %d", opcode); + packet_integrity_check(0, 1, SSH_CMSG_REQUEST_PTY); + goto set; + } + } + + set: + if (*n_bytes_ptr != n_bytes) + { + *n_bytes_ptr = n_bytes; + return; /* Don't process bytes passed */ + } + + if (failure == -1) + return; /* Packet parsed ok but tty stuff failed */ + + /* Set the new modes for the terminal. */ + if (tcsetattr(fd, TCSANOW, &tio) < 0) + log("Setting tty modes failed: %.100s", strerror(errno)); + return; +} diff --git a/ttymodes.h b/ttymodes.h new file mode 100644 index 00000000..3db5f33f --- /dev/null +++ b/ttymodes.h @@ -0,0 +1,138 @@ +/* + +ttymodes.h + +Author: Tatu Ylonen + SGTTY stuff contributed by Janne Snabb + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Tue Mar 21 15:42:09 1995 ylo + +*/ + +/* RCSID("$Id$"); */ + +/* The tty mode description is a stream of bytes. The stream consists of + opcode-arguments pairs. It is terminated by opcode TTY_OP_END (0). + Opcodes 1-127 have one-byte arguments. Opcodes 128-159 have integer + arguments. Opcodes 160-255 are not yet defined, and cause parsing to + stop (they should only be used after any other data). + + The client puts in the stream any modes it knows about, and the + server ignores any modes it does not know about. This allows some degree + of machine-independence, at least between systems that use a posix-like + tty interface. The protocol can support other systems as well, but might + require reimplementing as mode names would likely be different. */ + +/* Some constants and prototypes are defined in packet.h; this file + is only intended for including from ttymodes.h. */ + +/* termios macro */ /* sgtty macro */ +/* name, op */ +TTYCHAR(VINTR, 1) SGTTYCHAR(tiotc.t_intrc, 1) +TTYCHAR(VQUIT, 2) SGTTYCHAR(tiotc.t_quitc, 2) +TTYCHAR(VERASE, 3) SGTTYCHAR(tio.sg_erase, 3) +#if defined(VKILL) +TTYCHAR(VKILL, 4) SGTTYCHAR(tio.sg_kill, 4) +#endif /* VKILL */ +TTYCHAR(VEOF, 5) SGTTYCHAR(tiotc.t_eofc, 5) +#if defined(VEOL) +TTYCHAR(VEOL, 6) SGTTYCHAR(tiotc.t_brkc, 6) +#endif /* VEOL */ +#ifdef VEOL2 /* n/a */ +TTYCHAR(VEOL2, 7) +#endif /* VEOL2 */ +TTYCHAR(VSTART, 8) SGTTYCHAR(tiotc.t_startc, 8) +TTYCHAR(VSTOP, 9) SGTTYCHAR(tiotc.t_stopc, 9) +#if defined(VSUSP) +TTYCHAR(VSUSP, 10) SGTTYCHAR(tioltc.t_suspc, 10) +#endif /* VSUSP */ +#if defined(VDSUSP) +TTYCHAR(VDSUSP, 11) SGTTYCHAR(tioltc.t_dsuspc, 11) +#endif /* VDSUSP */ +#if defined(VREPRINT) +TTYCHAR(VREPRINT, 12) SGTTYCHAR(tioltc.t_rprntc, 12) +#endif /* VREPRINT */ +#if defined(VWERASE) +TTYCHAR(VWERASE, 13) SGTTYCHAR(tioltc.t_werasc, 13) +#endif /* VWERASE */ +#if defined(VLNEXT) +TTYCHAR(VLNEXT, 14) SGTTYCHAR(tioltc.t_lnextc, 14) +#endif /* VLNEXT */ +#if defined(VFLUSH) +TTYCHAR(VFLUSH, 15) SGTTYCHAR(tioltc.t_flushc, 15) +#endif /* VFLUSH */ +#ifdef VSWTCH +TTYCHAR(VSWTCH, 16) /* n/a */ +#endif /* VSWTCH */ +#if defined(VSTATUS) +TTYCHAR(VSTATUS, 17) SGTTYCHAR(tiots.tc_statusc, 17) +#endif /* VSTATUS */ +#ifdef VDISCARD +TTYCHAR(VDISCARD, 18) /* n/a */ +#endif /* VDISCARD */ + +/* name, field, op */ +TTYMODE(IGNPAR, c_iflag, 30) /* n/a */ +TTYMODE(PARMRK, c_iflag, 31) /* n/a */ +TTYMODE(INPCK, c_iflag, 32) SGTTYMODEN(ANYP, tio.sg_flags, 32) +TTYMODE(ISTRIP, c_iflag, 33) SGTTYMODEN(LPASS8, tiolm, 33) +TTYMODE(INLCR, c_iflag, 34) /* n/a */ +TTYMODE(IGNCR, c_iflag, 35) /* n/a */ +TTYMODE(ICRNL, c_iflag, 36) SGTTYMODE(CRMOD, tio.sg_flags, 36) +#if defined(IUCLC) +TTYMODE(IUCLC, c_iflag, 37) SGTTYMODE(LCASE, tio.sg_flags, 37) +#endif +TTYMODE(IXON, c_iflag, 38) /* n/a */ +TTYMODE(IXANY, c_iflag, 39) SGTTYMODEN(LDECCTQ, tiolm, 39) +TTYMODE(IXOFF, c_iflag, 40) SGTTYMODE(TANDEM, tio.sg_flags, 40) +#ifdef IMAXBEL +TTYMODE(IMAXBEL,c_iflag, 41) /* n/a */ +#endif /* IMAXBEL */ + +TTYMODE(ISIG, c_lflag, 50) /* n/a */ +TTYMODE(ICANON, c_lflag, 51) SGTTYMODEN(CBREAK, tio.sg_flags, 51) +#ifdef XCASE +TTYMODE(XCASE, c_lflag, 52) /* n/a */ +#endif +TTYMODE(ECHO, c_lflag, 53) SGTTYMODE(ECHO, tio.sg_flags, 53) +TTYMODE(ECHOE, c_lflag, 54) SGTTYMODE(LCRTERA, tiolm, 54) +TTYMODE(ECHOK, c_lflag, 55) SGTTYMODE(LCRTKIL, tiolm, 55) +TTYMODE(ECHONL, c_lflag, 56) /* n/a */ +TTYMODE(NOFLSH, c_lflag, 57) SGTTYMODE(LNOFLSH, tiolm, 57) +TTYMODE(TOSTOP, c_lflag, 58) SGTTYMODE(LTOSTOP, tiolm, 58) +#ifdef IEXTEN +TTYMODE(IEXTEN, c_lflag, 59) /* n/a */ +#endif /* IEXTEN */ +#if defined(ECHOCTL) +TTYMODE(ECHOCTL,c_lflag, 60) SGTTYMODE(LCTLECH, tiolm, 60) +#endif /* ECHOCTL */ +#ifdef ECHOKE +TTYMODE(ECHOKE, c_lflag, 61) /* n/a */ +#endif /* ECHOKE */ +#if defined(PENDIN) +TTYMODE(PENDIN, c_lflag, 62) SGTTYMODE(LPENDIN, tiolm, 62) +#endif /* PENDIN */ + +TTYMODE(OPOST, c_oflag, 70) /* n/a */ +#if defined(OLCUC) +TTYMODE(OLCUC, c_oflag, 71) SGTTYMODE(LCASE, tio.sg_flags, 71) +#endif +TTYMODE(ONLCR, c_oflag, 72) SGTTYMODE(CRMOD, tio.sg_flags, 72) +#ifdef OCRNL +TTYMODE(OCRNL, c_oflag, 73) /* n/a */ +#endif +#ifdef ONOCR +TTYMODE(ONOCR, c_oflag, 74) /* n/a */ +#endif +#ifdef ONLRET +TTYMODE(ONLRET, c_oflag, 75) /* n/a */ +#endif + +TTYMODE(CS7, c_cflag, 90) /* n/a */ +TTYMODE(CS8, c_cflag, 91) SGTTYMODE(LPASS8, tiolm, 91) +TTYMODE(PARENB, c_cflag, 92) /* n/a */ +TTYMODE(PARODD, c_cflag, 93) SGTTYMODE(ODDP, tio.sg_flags, 93) + diff --git a/uidswap.c b/uidswap.c new file mode 100644 index 00000000..de9e4625 --- /dev/null +++ b/uidswap.c @@ -0,0 +1,95 @@ +/* + +uidswap.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Sep 9 01:56:14 1995 ylo + +Code for uid-swapping. + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" +#include "uidswap.h" + +/* Note: all these functions must work in all of the following cases: + + 1. euid=0, ruid=0 + 2. euid=0, ruid!=0 + 3. euid!=0, ruid!=0 + + Additionally, they must work regardless of whether the system has + POSIX saved uids or not. */ + +#ifdef _POSIX_SAVED_IDS +/* Lets assume that posix saved ids also work with seteuid, even though that + is not part of the posix specification. */ +#define SAVED_IDS_WORK_WITH_SETEUID +#endif /* _POSIX_SAVED_IDS */ + +/* Saved effective uid. */ +static uid_t saved_euid = 0; + +/* Temporarily changes to the given uid. If the effective user id is not + root, this does nothing. This call cannot be nested. */ + +void temporarily_use_uid(uid_t uid) +{ +#ifdef SAVED_IDS_WORK_WITH_SETEUID + + /* Save the current euid. */ + saved_euid = geteuid(); + + /* Set the effective uid to the given (unprivileged) uid. */ + if (seteuid(uid) == -1) + debug("seteuid %d: %.100s", (int)uid, strerror(errno)); + +#else /* SAVED_IDS_WORK_WITH_SETUID */ + + /* Propagate the privileged uid to all of our uids. */ + if (setuid(geteuid()) < 0) + debug("setuid %d: %.100s", (int)geteuid(), strerror(errno)); + + /* Set the effective uid to the given (unprivileged) uid. */ + if (seteuid(uid) == -1) + debug("seteuid %d: %.100s", (int)uid, strerror(errno)); + +#endif /* SAVED_IDS_WORK_WITH_SETEUID */ + +} + +/* Restores to the original uid. */ + +void restore_uid() +{ +#ifdef SAVED_IDS_WORK_WITH_SETEUID + + /* Set the effective uid back to the saved uid. */ + if (seteuid(saved_euid) < 0) + debug("seteuid %d: %.100s", (int)saved_euid, strerror(errno)); + +#else /* SAVED_IDS_WORK_WITH_SETEUID */ + + /* We are unable to restore the real uid to its unprivileged value. */ + /* Propagate the real uid (usually more privileged) to effective uid + as well. */ + setuid(getuid()); + +#endif /* SAVED_IDS_WORK_WITH_SETEUID */ +} + +/* Permanently sets all uids to the given uid. This cannot be called while + temporarily_use_uid is effective. */ + +void permanently_set_uid(uid_t uid) +{ + if (setuid(uid) < 0) + debug("setuid %d: %.100s", (int)uid, strerror(errno)); +} diff --git a/uidswap.h b/uidswap.h new file mode 100644 index 00000000..af4f924f --- /dev/null +++ b/uidswap.h @@ -0,0 +1,30 @@ +/* + +uidswap.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Sat Sep 9 01:43:15 1995 ylo +Last modified: Sat Sep 9 02:34:04 1995 ylo + +*/ + +#ifndef UIDSWAP_H +#define UIDSWAP_H + +/* Temporarily changes to the given uid. If the effective user id is not + root, this does nothing. This call cannot be nested. */ +void temporarily_use_uid(uid_t uid); + +/* Restores the original effective user id after temporarily_use_uid(). + This should only be called while temporarily_use_uid is effective. */ +void restore_uid(); + +/* Permanently sets all uids to the given uid. This cannot be called while + temporarily_use_uid is effective. This must also clear any saved uids. */ +void permanently_set_uid(uid_t uid); + +#endif /* UIDSWAP_H */ diff --git a/version.h b/version.h new file mode 100644 index 00000000..8d2fc5c2 --- /dev/null +++ b/version.h @@ -0,0 +1 @@ +#define SSH_VERSION "OpenSSH-1.2" diff --git a/xmalloc.c b/xmalloc.c new file mode 100644 index 00000000..4a8d190c --- /dev/null +++ b/xmalloc.c @@ -0,0 +1,56 @@ +/* + +xmalloc.c + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Mon Mar 20 21:23:10 1995 ylo + +Versions of malloc and friends that check their results, and never return +failure (they call fatal if they encounter an error). + +*/ + +#include "includes.h" +RCSID("$Id$"); + +#include "ssh.h" + +void *xmalloc(size_t size) +{ + void *ptr = malloc(size); + if (ptr == NULL) + fatal("xmalloc: out of memory (allocating %d bytes)", (int)size); + return ptr; +} + +void *xrealloc(void *ptr, size_t new_size) +{ + void *new_ptr; + + if (ptr == NULL) + fatal("xrealloc: NULL pointer given as argument"); + new_ptr = realloc(ptr, new_size); + if (new_ptr == NULL) + fatal("xrealloc: out of memory (new_size %d bytes)", (int)new_size); + return new_ptr; +} + +void xfree(void *ptr) +{ + if (ptr == NULL) + fatal("xfree: NULL pointer given as argument"); + free(ptr); +} + +char *xstrdup(const char *str) +{ + int len = strlen(str) + 1; + + char *cp = xmalloc(len); + strlcpy(cp, str, len); + return cp; +} diff --git a/xmalloc.h b/xmalloc.h new file mode 100644 index 00000000..28d8852e --- /dev/null +++ b/xmalloc.h @@ -0,0 +1,34 @@ +/* + +xmalloc.h + +Author: Tatu Ylonen + +Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + All rights reserved + +Created: Mon Mar 20 22:09:17 1995 ylo + +Versions of malloc and friends that check their results, and never return +failure (they call fatal if they encounter an error). + +*/ + +/* RCSID("$Id$"); */ + +#ifndef XMALLOC_H +#define XMALLOC_H + +/* Like malloc, but calls fatal() if out of memory. */ +void *xmalloc(size_t size); + +/* Like realloc, but calls fatal() if out of memory. */ +void *xrealloc(void *ptr, size_t new_size); + +/* Frees memory allocated using xmalloc or xrealloc. */ +void xfree(void *ptr); + +/* Allocates memory using xmalloc, and copies the string into that memory. */ +char *xstrdup(const char *str); + +#endif /* XMALLOC_H */ -- 2.45.1