1 /* $OpenBSD: sshd.c,v 1.366 2009/01/22 10:02:34 djm Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This program is the ssh daemon. It listens for connections from clients,
7 * and performs authentication, executes use commands or shell, and forwards
8 * information to/from the application to the user client over an encrypted
9 * connection. This can also handle forwarding of X11, TCP/IP, and
10 * authentication agent connections.
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
18 * SSH2 implementation:
19 * Privilege Separation:
21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22 * Copyright (c) 2002 Niels Provos. All rights reserved.
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
47 #include <sys/types.h>
48 #include <sys/ioctl.h>
49 #include <sys/socket.h>
50 #ifdef HAVE_SYS_STAT_H
51 # include <sys/stat.h>
53 #ifdef HAVE_SYS_TIME_H
54 # include <sys/time.h>
56 #include "openbsd-compat/sys-tree.h"
57 #include "openbsd-compat/sys-queue.h"
75 #include <openssl/dh.h>
76 #include <openssl/bn.h>
77 #include <openssl/md5.h>
78 #include <openssl/rand.h>
79 #include "openbsd-compat/openssl-compat.h"
81 #ifdef HAVE_SECUREWARE
82 #include <sys/security.h>
102 #include "myproposal.h"
103 #include "authfile.h"
104 #include "pathnames.h"
105 #include "atomicio.h"
106 #include "canohost.h"
107 #include "hostfile.h"
111 #include "dispatch.h"
112 #include "channels.h"
114 #include "monitor_mm.h"
119 #include "monitor_wrap.h"
122 #ifdef USE_SECURITY_SESSION_API
123 #include <Security/AuthSession.h>
138 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
139 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
140 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
141 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
146 extern char *__progname;
148 /* Server configuration options. */
149 ServerOptions options;
151 /* Name of the server configuration file. */
152 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
155 * Debug mode flag. This can be set on the command line. If debug
156 * mode is enabled, extra debugging output will be sent to the system
157 * log, the daemon will not go to background, and will exit after processing
158 * the first connection.
162 /* Flag indicating that the daemon should only test the configuration and keys. */
165 /* Flag indicating that the daemon is being started from inetd. */
168 /* Flag indicating that sshd should not detach and become a daemon. */
169 int no_daemon_flag = 0;
171 /* debug goes to stderr unless inetd_flag is set */
174 /* Saved arguments to main(). */
179 int rexeced_flag = 0;
185 * The sockets that the server is listening; this is used in the SIGHUP
188 #define MAX_LISTEN_SOCKS 16
189 int listen_socks[MAX_LISTEN_SOCKS];
190 int num_listen_socks = 0;
193 * the client's version string, passed by sshd2 in compat mode. if != NULL,
194 * sshd will skip the version-number exchange
196 char *client_version_string = NULL;
197 char *server_version_string = NULL;
199 /* for rekeying XXX fixme */
203 * Any really sensitive data in the application is contained in this
204 * structure. The idea is that this structure could be locked into memory so
205 * that the pages do not get written into swap. However, there are some
206 * problems. The private key contains BIGNUMs, and we do not (in principle)
207 * have access to the internals of them, and locking just the structure is
208 * not very useful. Currently, memory locking is not implemented.
211 Key *server_key; /* ephemeral server key */
212 Key *ssh1_host_key; /* ssh1 host key */
213 Key **host_keys; /* all private host keys */
216 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
220 * Flag indicating whether the RSA server key needs to be regenerated.
221 * Is set in the SIGALRM handler and cleared when the key is regenerated.
223 static volatile sig_atomic_t key_do_regen = 0;
225 /* This is set to true when a signal is received. */
226 static volatile sig_atomic_t received_sighup = 0;
227 static volatile sig_atomic_t received_sigterm = 0;
229 /* session identifier, used by RSA-auth */
230 u_char session_id[16];
233 u_char *session_id2 = NULL;
234 u_int session_id2_len = 0;
236 /* record remote hostname or ip */
237 u_int utmp_len = MAXHOSTNAMELEN;
239 /* options.max_startup sized array of fd ints */
240 int *startup_pipes = NULL;
241 int startup_pipe; /* in child */
243 /* variables used for privilege separation */
244 int use_privsep = -1;
245 struct monitor *pmonitor = NULL;
247 /* global authentication context */
248 Authctxt *the_authctxt = NULL;
250 /* sshd_config buffer */
253 /* message to be displayed after login */
256 /* Unprivileged user */
257 struct passwd *privsep_pw = NULL;
259 /* Prototypes for various functions defined later in this file. */
260 void destroy_sensitive_data(void);
261 void demote_sensitive_data(void);
263 static void do_ssh1_kex(void);
264 static void do_ssh2_kex(void);
267 * Close all listening sockets
270 close_listen_socks(void)
274 for (i = 0; i < num_listen_socks; i++)
275 close(listen_socks[i]);
276 num_listen_socks = -1;
280 close_startup_pipes(void)
285 for (i = 0; i < options.max_startups; i++)
286 if (startup_pipes[i] != -1)
287 close(startup_pipes[i]);
291 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
292 * the effect is to reread the configuration file (and to regenerate
298 sighup_handler(int sig)
300 int save_errno = errno;
303 signal(SIGHUP, sighup_handler);
308 * Called from the main program after receiving SIGHUP.
309 * Restarts the server.
314 logit("Received SIGHUP; restarting.");
315 close_listen_socks();
316 close_startup_pipes();
317 alarm(0); /* alarm timer persists across exec */
318 execv(saved_argv[0], saved_argv);
319 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
325 * Generic signal handler for terminating signals in the master daemon.
329 sigterm_handler(int sig)
331 received_sigterm = sig;
335 * SIGCHLD handler. This is called whenever a child dies. This will then
336 * reap any zombies left by exited children.
340 main_sigchld_handler(int sig)
342 int save_errno = errno;
346 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
347 (pid < 0 && errno == EINTR))
350 signal(SIGCHLD, main_sigchld_handler);
355 * Signal handler for the alarm after the login grace period has expired.
359 grace_alarm_handler(int sig)
361 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
362 kill(pmonitor->m_pid, SIGALRM);
364 /* Log error and exit. */
365 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
369 * Signal handler for the key regeneration alarm. Note that this
370 * alarm only occurs in the daemon waiting for connections, and it does not
371 * do anything with the private key or random state before forking.
372 * Thus there should be no concurrency control/asynchronous execution
376 generate_ephemeral_server_key(void)
378 verbose("Generating %s%d bit RSA key.",
379 sensitive_data.server_key ? "new " : "", options.server_key_bits);
380 if (sensitive_data.server_key != NULL)
381 key_free(sensitive_data.server_key);
382 sensitive_data.server_key = key_generate(KEY_RSA1,
383 options.server_key_bits);
384 verbose("RSA key generation complete.");
386 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
392 key_regeneration_alarm(int sig)
394 int save_errno = errno;
396 signal(SIGALRM, SIG_DFL);
402 sshd_exchange_identification(int sock_in, int sock_out)
406 int remote_major, remote_minor;
408 char *s, *newline = "\n";
409 char buf[256]; /* Must not be larger than remote_version. */
410 char remote_version[256]; /* Must be at least as big as buf. */
412 if ((options.protocol & SSH_PROTO_1) &&
413 (options.protocol & SSH_PROTO_2)) {
414 major = PROTOCOL_MAJOR_1;
416 } else if (options.protocol & SSH_PROTO_2) {
417 major = PROTOCOL_MAJOR_2;
418 minor = PROTOCOL_MINOR_2;
421 major = PROTOCOL_MAJOR_1;
422 minor = PROTOCOL_MINOR_1;
424 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
425 SSH_RELEASE, newline);
426 server_version_string = xstrdup(buf);
428 /* Send our protocol version identification. */
429 if (atomicio(vwrite, sock_out, server_version_string,
430 strlen(server_version_string))
431 != strlen(server_version_string)) {
432 logit("Could not write ident string to %s", get_remote_ipaddr());
436 /* Read other sides version identification. */
437 memset(buf, 0, sizeof(buf));
438 for (i = 0; i < sizeof(buf) - 1; i++) {
439 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
440 logit("Did not receive identification string from %s",
441 get_remote_ipaddr());
444 if (buf[i] == '\r') {
446 /* Kludge for F-Secure Macintosh < 1.0.2 */
448 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
452 if (buf[i] == '\n') {
457 buf[sizeof(buf) - 1] = 0;
458 client_version_string = xstrdup(buf);
461 * Check that the versions match. In future this might accept
462 * several versions and set appropriate flags to handle them.
464 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
465 &remote_major, &remote_minor, remote_version) != 3) {
466 s = "Protocol mismatch.\n";
467 (void) atomicio(vwrite, sock_out, s, strlen(s));
470 logit("Bad protocol version identification '%.100s' from %s",
471 client_version_string, get_remote_ipaddr());
474 debug("Client protocol version %d.%d; client software version %.100s",
475 remote_major, remote_minor, remote_version);
476 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s",
477 get_remote_ipaddr(), get_remote_port(),
478 remote_major, remote_minor, remote_version);
480 compat_datafellows(remote_version);
482 if (datafellows & SSH_BUG_PROBE) {
483 logit("probed from %s with %s. Don't panic.",
484 get_remote_ipaddr(), client_version_string);
488 if (datafellows & SSH_BUG_SCANNER) {
489 logit("scanned from %s with %s. Don't panic.",
490 get_remote_ipaddr(), client_version_string);
495 switch (remote_major) {
497 if (remote_minor == 99) {
498 if (options.protocol & SSH_PROTO_2)
504 if (!(options.protocol & SSH_PROTO_1)) {
508 if (remote_minor < 3) {
509 packet_disconnect("Your ssh version is too old and "
510 "is no longer supported. Please install a newer version.");
511 } else if (remote_minor == 3) {
512 /* note that this disables agent-forwarding */
517 if (options.protocol & SSH_PROTO_2) {
526 chop(server_version_string);
527 debug("Local version string %.200s", server_version_string);
530 s = "Protocol major versions differ.\n";
531 (void) atomicio(vwrite, sock_out, s, strlen(s));
534 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
536 server_version_string, client_version_string);
541 /* Destroy the host and server keys. They will no longer be needed. */
543 destroy_sensitive_data(void)
547 if (sensitive_data.server_key) {
548 key_free(sensitive_data.server_key);
549 sensitive_data.server_key = NULL;
551 for (i = 0; i < options.num_host_key_files; i++) {
552 if (sensitive_data.host_keys[i]) {
553 key_free(sensitive_data.host_keys[i]);
554 sensitive_data.host_keys[i] = NULL;
557 sensitive_data.ssh1_host_key = NULL;
558 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
561 /* Demote private to public keys for network child */
563 demote_sensitive_data(void)
568 if (sensitive_data.server_key) {
569 tmp = key_demote(sensitive_data.server_key);
570 key_free(sensitive_data.server_key);
571 sensitive_data.server_key = tmp;
574 for (i = 0; i < options.num_host_key_files; i++) {
575 if (sensitive_data.host_keys[i]) {
576 tmp = key_demote(sensitive_data.host_keys[i]);
577 key_free(sensitive_data.host_keys[i]);
578 sensitive_data.host_keys[i] = tmp;
579 if (tmp->type == KEY_RSA1)
580 sensitive_data.ssh1_host_key = tmp;
584 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
588 privsep_preauth_child(void)
593 /* Enable challenge-response authentication for privilege separation */
594 privsep_challenge_enable();
597 arc4random_buf(rnd, sizeof(rnd));
598 RAND_seed(rnd, sizeof(rnd));
600 /* Demote the private keys to public keys. */
601 demote_sensitive_data();
603 /* Change our root directory */
604 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
605 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
607 if (chdir("/") == -1)
608 fatal("chdir(\"/\"): %s", strerror(errno));
610 /* Drop our privileges */
611 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
612 (u_int)privsep_pw->pw_gid);
614 /* XXX not ready, too heavy after chroot */
615 do_setusercontext(privsep_pw);
617 gidset[0] = privsep_pw->pw_gid;
618 if (setgroups(1, gidset) < 0)
619 fatal("setgroups: %.100s", strerror(errno));
620 permanently_set_uid(privsep_pw);
625 privsep_preauth(Authctxt *authctxt)
630 /* Set up unprivileged child process to deal with network data */
631 pmonitor = monitor_init();
632 /* Store a pointer to the kex for later rekeying */
633 pmonitor->m_pkex = &xxx_kex;
637 fatal("fork of unprivileged child failed");
638 } else if (pid != 0) {
639 debug2("Network child is on pid %ld", (long)pid);
641 close(pmonitor->m_recvfd);
642 pmonitor->m_pid = pid;
643 monitor_child_preauth(authctxt, pmonitor);
644 close(pmonitor->m_sendfd);
647 monitor_sync(pmonitor);
649 /* Wait for the child's exit status */
650 while (waitpid(pid, &status, 0) < 0)
657 close(pmonitor->m_sendfd);
659 /* Demote the child */
660 if (getuid() == 0 || geteuid() == 0)
661 privsep_preauth_child();
662 setproctitle("%s", "[net]");
668 privsep_postauth(Authctxt *authctxt)
672 #ifdef DISABLE_FD_PASSING
675 if (authctxt->pw->pw_uid == 0 || options.use_login) {
677 /* File descriptor passing is broken or root login */
682 /* New socket pair */
683 monitor_reinit(pmonitor);
685 pmonitor->m_pid = fork();
686 if (pmonitor->m_pid == -1)
687 fatal("fork of unprivileged child failed");
688 else if (pmonitor->m_pid != 0) {
689 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
690 close(pmonitor->m_recvfd);
691 buffer_clear(&loginmsg);
692 monitor_child_postauth(pmonitor);
698 close(pmonitor->m_sendfd);
700 /* Demote the private keys to public keys. */
701 demote_sensitive_data();
704 arc4random_buf(rnd, sizeof(rnd));
705 RAND_seed(rnd, sizeof(rnd));
707 /* Drop privileges */
708 do_setusercontext(authctxt->pw);
711 /* It is safe now to apply the key state */
712 monitor_apply_keystate(pmonitor);
715 * Tell the packet layer that authentication was successful, since
716 * this information is not part of the key state.
718 packet_set_authenticated();
722 list_hostkey_types(void)
730 for (i = 0; i < options.num_host_key_files; i++) {
731 Key *key = sensitive_data.host_keys[i];
737 if (buffer_len(&b) > 0)
738 buffer_append(&b, ",", 1);
739 p = key_ssh_name(key);
740 buffer_append(&b, p, strlen(p));
744 buffer_append(&b, "\0", 1);
745 ret = xstrdup(buffer_ptr(&b));
747 debug("list_hostkey_types: %s", ret);
752 get_hostkey_by_type(int type)
756 for (i = 0; i < options.num_host_key_files; i++) {
757 Key *key = sensitive_data.host_keys[i];
758 if (key != NULL && key->type == type)
765 get_hostkey_by_index(int ind)
767 if (ind < 0 || ind >= options.num_host_key_files)
769 return (sensitive_data.host_keys[ind]);
773 get_hostkey_index(Key *key)
777 for (i = 0; i < options.num_host_key_files; i++) {
778 if (key == sensitive_data.host_keys[i])
785 * returns 1 if connection should be dropped, 0 otherwise.
786 * dropping starts at connection #max_startups_begin with a probability
787 * of (max_startups_rate/100). the probability increases linearly until
788 * all connections are dropped for startups > max_startups
791 drop_connection(int startups)
795 if (startups < options.max_startups_begin)
797 if (startups >= options.max_startups)
799 if (options.max_startups_rate == 100)
802 p = 100 - options.max_startups_rate;
803 p *= startups - options.max_startups_begin;
804 p /= options.max_startups - options.max_startups_begin;
805 p += options.max_startups_rate;
806 r = arc4random_uniform(100);
808 debug("drop_connection: p %d, r %d", p, r);
809 return (r < p) ? 1 : 0;
815 fprintf(stderr, "%s, %s\n",
816 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
818 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n"
819 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n"
820 " [-o option] [-p port] [-u len]\n"
826 send_rexec_state(int fd, Buffer *conf)
830 debug3("%s: entering fd = %d config len %d", __func__, fd,
834 * Protocol from reexec master to child:
835 * string configuration
836 * u_int ephemeral_key_follows
837 * bignum e (only if ephemeral_key_follows == 1)
843 * string rngseed (only if OpenSSL is not self-seeded)
846 buffer_put_cstring(&m, buffer_ptr(conf));
848 if (sensitive_data.server_key != NULL &&
849 sensitive_data.server_key->type == KEY_RSA1) {
850 buffer_put_int(&m, 1);
851 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
852 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
853 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
854 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
855 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
856 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
858 buffer_put_int(&m, 0);
860 #ifndef OPENSSL_PRNG_ONLY
861 rexec_send_rng_seed(&m);
864 if (ssh_msg_send(fd, 0, &m) == -1)
865 fatal("%s: ssh_msg_send failed", __func__);
869 debug3("%s: done", __func__);
873 recv_rexec_state(int fd, Buffer *conf)
879 debug3("%s: entering fd = %d", __func__, fd);
883 if (ssh_msg_recv(fd, &m) == -1)
884 fatal("%s: ssh_msg_recv failed", __func__);
885 if (buffer_get_char(&m) != 0)
886 fatal("%s: rexec version mismatch", __func__);
888 cp = buffer_get_string(&m, &len);
890 buffer_append(conf, cp, len + 1);
893 if (buffer_get_int(&m)) {
894 if (sensitive_data.server_key != NULL)
895 key_free(sensitive_data.server_key);
896 sensitive_data.server_key = key_new_private(KEY_RSA1);
897 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
898 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
899 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
900 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
901 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
902 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
903 rsa_generate_additional_parameters(
904 sensitive_data.server_key->rsa);
907 #ifndef OPENSSL_PRNG_ONLY
908 rexec_recv_rng_seed(&m);
913 debug3("%s: done", __func__);
916 /* Accept a connection from inetd */
918 server_accept_inetd(int *sock_in, int *sock_out)
924 close(REEXEC_CONFIG_PASS_FD);
925 *sock_in = *sock_out = dup(STDIN_FILENO);
927 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
928 close(REEXEC_STARTUP_PIPE_FD);
931 *sock_in = dup(STDIN_FILENO);
932 *sock_out = dup(STDOUT_FILENO);
935 * We intentionally do not close the descriptors 0, 1, and 2
936 * as our code for setting the descriptors won't work if
937 * ttyfd happens to be one of those.
939 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
940 dup2(fd, STDIN_FILENO);
941 dup2(fd, STDOUT_FILENO);
942 if (fd > STDOUT_FILENO)
945 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
949 * Listen for TCP connections
954 int ret, listen_sock, on = 1;
956 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
958 int socksizelen = sizeof(int);
960 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
961 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
963 if (num_listen_socks >= MAX_LISTEN_SOCKS)
964 fatal("Too many listen sockets. "
965 "Enlarge MAX_LISTEN_SOCKS");
966 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
967 ntop, sizeof(ntop), strport, sizeof(strport),
968 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
969 error("getnameinfo failed: %.100s",
970 ssh_gai_strerror(ret));
973 /* Create socket for listening. */
974 listen_sock = socket(ai->ai_family, ai->ai_socktype,
976 if (listen_sock < 0) {
977 /* kernel may not support ipv6 */
978 verbose("socket: %.100s", strerror(errno));
981 if (set_nonblock(listen_sock) == -1) {
986 * Set socket options.
987 * Allow local port reuse in TIME_WAIT.
989 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
990 &on, sizeof(on)) == -1)
991 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
994 /* Only communicate in IPv6 over AF_INET6 sockets. */
995 if (ai->ai_family == AF_INET6) {
996 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY,
997 &on, sizeof(on)) == -1)
998 error("setsockopt IPV6_V6ONLY: %s",
1003 debug("Bind to port %s on %s.", strport, ntop);
1005 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF,
1006 &socksize, &socksizelen);
1007 debug("Server TCP RWIN socket size: %d", socksize);
1008 debug("HPN Buffer Size: %d", options.hpn_buffer_size);
1010 /* Bind the socket to the desired port. */
1011 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1012 error("Bind to port %s on %s failed: %.200s.",
1013 strport, ntop, strerror(errno));
1017 listen_socks[num_listen_socks] = listen_sock;
1020 /* Start listening on the port. */
1021 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1022 fatal("listen on [%s]:%s: %.100s",
1023 ntop, strport, strerror(errno));
1024 logit("Server listening on %s port %s.", ntop, strport);
1026 freeaddrinfo(options.listen_addrs);
1028 if (!num_listen_socks)
1029 fatal("Cannot bind any address.");
1033 * The main TCP accept loop. Note that, for the non-debug case, returns
1034 * from this function are in a forked subprocess.
1037 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1040 int i, j, ret, maxfd;
1041 int key_used = 0, startups = 0;
1042 int startup_p[2] = { -1 , -1 };
1043 struct sockaddr_storage from;
1047 /* setup fd set for accept */
1050 for (i = 0; i < num_listen_socks; i++)
1051 if (listen_socks[i] > maxfd)
1052 maxfd = listen_socks[i];
1053 /* pipes connected to unauthenticated childs */
1054 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1055 for (i = 0; i < options.max_startups; i++)
1056 startup_pipes[i] = -1;
1059 * Stay listening for connections until the system crashes or
1060 * the daemon is killed with a signal.
1063 if (received_sighup)
1067 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1070 for (i = 0; i < num_listen_socks; i++)
1071 FD_SET(listen_socks[i], fdset);
1072 for (i = 0; i < options.max_startups; i++)
1073 if (startup_pipes[i] != -1)
1074 FD_SET(startup_pipes[i], fdset);
1076 /* Wait in select until there is a connection. */
1077 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1078 if (ret < 0 && errno != EINTR)
1079 error("select: %.100s", strerror(errno));
1080 if (received_sigterm) {
1081 logit("Received signal %d; terminating.",
1082 (int) received_sigterm);
1083 close_listen_socks();
1084 unlink(options.pid_file);
1087 if (key_used && key_do_regen) {
1088 generate_ephemeral_server_key();
1095 for (i = 0; i < options.max_startups; i++)
1096 if (startup_pipes[i] != -1 &&
1097 FD_ISSET(startup_pipes[i], fdset)) {
1099 * the read end of the pipe is ready
1100 * if the child has closed the pipe
1101 * after successful authentication
1102 * or if the child has died
1104 close(startup_pipes[i]);
1105 startup_pipes[i] = -1;
1108 for (i = 0; i < num_listen_socks; i++) {
1109 if (!FD_ISSET(listen_socks[i], fdset))
1111 fromlen = sizeof(from);
1112 *newsock = accept(listen_socks[i],
1113 (struct sockaddr *)&from, &fromlen);
1115 if (errno != EINTR && errno != EAGAIN &&
1116 errno != EWOULDBLOCK)
1117 error("accept: %.100s", strerror(errno));
1120 if (unset_nonblock(*newsock) == -1) {
1124 if (drop_connection(startups) == 1) {
1125 debug("drop connection #%d", startups);
1129 if (pipe(startup_p) == -1) {
1134 if (rexec_flag && socketpair(AF_UNIX,
1135 SOCK_STREAM, 0, config_s) == -1) {
1136 error("reexec socketpair: %s",
1139 close(startup_p[0]);
1140 close(startup_p[1]);
1144 for (j = 0; j < options.max_startups; j++)
1145 if (startup_pipes[j] == -1) {
1146 startup_pipes[j] = startup_p[0];
1147 if (maxfd < startup_p[0])
1148 maxfd = startup_p[0];
1154 * Got connection. Fork a child to handle it, unless
1155 * we are in debugging mode.
1159 * In debugging mode. Close the listening
1160 * socket, and start processing the
1161 * connection without forking.
1163 debug("Server will not fork when running in debugging mode.");
1164 close_listen_socks();
1165 *sock_in = *newsock;
1166 *sock_out = *newsock;
1167 close(startup_p[0]);
1168 close(startup_p[1]);
1172 send_rexec_state(config_s[0],
1180 * Normal production daemon. Fork, and have
1181 * the child process the connection. The
1182 * parent continues listening.
1184 platform_pre_fork();
1185 if ((pid = fork()) == 0) {
1187 * Child. Close the listening and
1188 * max_startup sockets. Start using
1189 * the accepted socket. Reinitialize
1190 * logging (since our pid has changed).
1191 * We break out of the loop to handle
1194 platform_post_fork_child();
1195 startup_pipe = startup_p[1];
1196 close_startup_pipes();
1197 close_listen_socks();
1198 *sock_in = *newsock;
1199 *sock_out = *newsock;
1200 log_init(__progname,
1202 options.log_facility,
1209 /* Parent. Stay in the loop. */
1210 platform_post_fork_parent(pid);
1212 error("fork: %.100s", strerror(errno));
1214 debug("Forked child %ld.", (long)pid);
1216 close(startup_p[1]);
1219 send_rexec_state(config_s[0], &cfg);
1225 * Mark that the key has been used (it
1226 * was "given" to the child).
1228 if ((options.protocol & SSH_PROTO_1) &&
1230 /* Schedule server key regeneration alarm. */
1231 signal(SIGALRM, key_regeneration_alarm);
1232 alarm(options.key_regeneration_time);
1239 * Ensure that our random state differs
1240 * from that of the child
1245 /* child process check (or debug mode) */
1246 if (num_listen_socks < 0)
1253 * Main program for the daemon.
1256 main(int ac, char **av)
1258 extern char *optarg;
1261 int sock_in = -1, sock_out = -1, newsock = -1;
1262 const char *remote_ip;
1263 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1265 char *line, *p, *cp;
1266 int config_s[2] = { -1 , -1 };
1267 u_int64_t ibytes, obytes;
1272 #ifdef HAVE_SECUREWARE
1273 (void)set_auth_parameters(ac, av);
1275 __progname = ssh_get_progname(av[0]);
1278 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1281 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1282 for (i = 0; i < ac; i++)
1283 saved_argv[i] = xstrdup(av[i]);
1284 saved_argv[i] = NULL;
1286 #ifndef HAVE_SETPROCTITLE
1287 /* Prepare for later setproctitle emulation */
1288 compat_init_setproctitle(ac, av);
1292 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1293 debug("setgroups(): %.200s", strerror(errno));
1295 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1298 /* Initialize configuration options to their default values. */
1299 initialize_server_options(&options);
1301 /* Parse command-line arguments. */
1302 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1305 options.address_family = AF_INET;
1308 options.address_family = AF_INET6;
1311 config_file_name = optarg;
1314 if (debug_flag == 0) {
1316 options.log_level = SYSLOG_LEVEL_DEBUG1;
1317 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1318 options.log_level++;
1340 options.log_level = SYSLOG_LEVEL_QUIET;
1343 options.server_key_bits = (int)strtonum(optarg, 256,
1347 options.ports_from_cmdline = 1;
1348 if (options.num_ports >= MAX_PORTS) {
1349 fprintf(stderr, "too many ports.\n");
1352 options.ports[options.num_ports++] = a2port(optarg);
1353 if (options.ports[options.num_ports-1] <= 0) {
1354 fprintf(stderr, "Bad port number.\n");
1359 if ((options.login_grace_time = convtime(optarg)) == -1) {
1360 fprintf(stderr, "Invalid login grace time.\n");
1365 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1366 fprintf(stderr, "Invalid key regeneration interval.\n");
1371 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1372 fprintf(stderr, "too many host keys.\n");
1375 options.host_key_files[options.num_host_key_files++] = optarg;
1385 while ((p = strsep(&cp, ",")) && *p != '\0') {
1386 if (strncmp(p, "addr=", 5) == 0)
1387 test_addr = xstrdup(p + 5);
1388 else if (strncmp(p, "host=", 5) == 0)
1389 test_host = xstrdup(p + 5);
1390 else if (strncmp(p, "user=", 5) == 0)
1391 test_user = xstrdup(p + 5);
1393 fprintf(stderr, "Invalid test "
1394 "mode specification %s\n", p);
1400 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1401 if (utmp_len > MAXHOSTNAMELEN) {
1402 fprintf(stderr, "Invalid utmp length.\n");
1407 line = xstrdup(optarg);
1408 if (process_server_config_line(&options, line,
1409 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1419 if (rexeced_flag || inetd_flag)
1421 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1422 fatal("sshd re-exec requires execution with an absolute path");
1424 closefrom(REEXEC_MIN_FREE_FD);
1426 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1428 SSLeay_add_all_algorithms();
1431 * Force logging to stderr until we have loaded the private host
1432 * key (unless started from inetd)
1434 log_init(__progname,
1435 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1436 SYSLOG_LEVEL_INFO : options.log_level,
1437 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1438 SYSLOG_FACILITY_AUTH : options.log_facility,
1439 log_stderr || !inetd_flag);
1442 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1443 * root's environment
1445 if (getenv("KRB5CCNAME") != NULL)
1446 unsetenv("KRB5CCNAME");
1449 /* Cray can define user privs drop all privs now!
1450 * Not needed on PRIV_SU systems!
1455 sensitive_data.server_key = NULL;
1456 sensitive_data.ssh1_host_key = NULL;
1457 sensitive_data.have_ssh1_key = 0;
1458 sensitive_data.have_ssh2_key = 0;
1461 * If we're doing an extended config test, make sure we have all of
1462 * the parameters we need. If we're not doing an extended test,
1463 * do not silently ignore connection test params.
1465 if (test_flag >= 2 &&
1466 (test_user != NULL || test_host != NULL || test_addr != NULL)
1467 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1468 fatal("user, host and addr are all required when testing "
1470 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1472 fatal("Config test connection parameter (-C) provided without "
1475 /* Fetch our configuration */
1478 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1480 load_server_config(config_file_name, &cfg);
1482 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1483 &cfg, NULL, NULL, NULL);
1487 /* Fill in default values for those options not explicitly set. */
1488 fill_default_server_options(&options);
1490 /* challenge-response is implemented via keyboard interactive */
1491 if (options.challenge_response_authentication)
1492 options.kbd_interactive_authentication = 1;
1494 /* set default channel AF */
1495 channel_set_af(options.address_family);
1497 /* Check that there are no remaining arguments. */
1499 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1503 debug("sshd version %.100s", SSH_RELEASE);
1505 /* Store privilege separation user for later use if required. */
1506 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1507 if (use_privsep || options.kerberos_authentication)
1508 fatal("Privilege separation user %s does not exist",
1511 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1512 privsep_pw = pwcopy(privsep_pw);
1513 xfree(privsep_pw->pw_passwd);
1514 privsep_pw->pw_passwd = xstrdup("*");
1518 /* load private host keys */
1519 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1521 for (i = 0; i < options.num_host_key_files; i++)
1522 sensitive_data.host_keys[i] = NULL;
1524 for (i = 0; i < options.num_host_key_files; i++) {
1525 key = key_load_private(options.host_key_files[i], "", NULL);
1526 sensitive_data.host_keys[i] = key;
1528 error("Could not load host key: %s",
1529 options.host_key_files[i]);
1530 sensitive_data.host_keys[i] = NULL;
1533 switch (key->type) {
1535 sensitive_data.ssh1_host_key = key;
1536 sensitive_data.have_ssh1_key = 1;
1540 sensitive_data.have_ssh2_key = 1;
1543 debug("private host key: #%d type %d %s", i, key->type,
1546 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1547 logit("Disabling protocol version 1. Could not load host key");
1548 options.protocol &= ~SSH_PROTO_1;
1551 /* The GSSAPI key exchange can run without a host key */
1552 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1553 logit("Disabling protocol version 2. Could not load host key");
1554 options.protocol &= ~SSH_PROTO_2;
1557 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1558 logit("sshd: no hostkeys available -- exiting.");
1562 /* Check certain values for sanity. */
1563 if (options.protocol & SSH_PROTO_1) {
1564 if (options.server_key_bits < 512 ||
1565 options.server_key_bits > 32768) {
1566 fprintf(stderr, "Bad server key size.\n");
1570 * Check that server and host key lengths differ sufficiently. This
1571 * is necessary to make double encryption work with rsaref. Oh, I
1572 * hate software patents. I dont know if this can go? Niels
1574 if (options.server_key_bits >
1575 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1576 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1577 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1578 SSH_KEY_BITS_RESERVED) {
1579 options.server_key_bits =
1580 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1581 SSH_KEY_BITS_RESERVED;
1582 debug("Forcing server key to %d bits to make it differ from host key.",
1583 options.server_key_bits);
1590 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1591 (S_ISDIR(st.st_mode) == 0))
1592 fatal("Missing privilege separation directory: %s",
1593 _PATH_PRIVSEP_CHROOT_DIR);
1596 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1597 (st.st_uid != getuid () ||
1598 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1600 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1602 fatal("%s must be owned by root and not group or "
1603 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1606 if (test_flag > 1) {
1607 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1608 parse_server_match_config(&options, test_user,
1609 test_host, test_addr);
1610 dump_config(&options);
1613 /* Configuration looks good, so exit if in test mode. */
1618 * Clear out any supplemental groups we may have inherited. This
1619 * prevents inadvertent creation of files with bad modes (in the
1620 * portable version at least, it's certainly possible for PAM
1621 * to create a file, and we can't control the code in every
1622 * module which might be used).
1624 if (setgroups(0, NULL) < 0)
1625 debug("setgroups() failed: %.200s", strerror(errno));
1628 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1629 for (i = 0; i < rexec_argc; i++) {
1630 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1631 rexec_argv[i] = saved_argv[i];
1633 rexec_argv[rexec_argc] = "-R";
1634 rexec_argv[rexec_argc + 1] = NULL;
1637 /* Ensure that umask disallows at least group and world write */
1638 new_umask = umask(0077) | 0022;
1639 (void) umask(new_umask);
1641 /* Initialize the log (it is reinitialized below in case we forked). */
1642 if (debug_flag && (!inetd_flag || rexeced_flag))
1644 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1647 * If not in debugging mode, and not started from inetd, disconnect
1648 * from the controlling terminal, and fork. The original process
1651 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1654 #endif /* TIOCNOTTY */
1655 if (daemon(0, 0) < 0)
1656 fatal("daemon() failed: %.200s", strerror(errno));
1658 /* Disconnect from the controlling tty. */
1660 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1662 (void) ioctl(fd, TIOCNOTTY, NULL);
1665 #endif /* TIOCNOTTY */
1667 /* Reinitialize the log (because of the fork above). */
1668 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1670 /* Initialize the random number generator. */
1673 /* Chdir to the root directory so that the current disk can be
1674 unmounted if desired. */
1677 /* ignore SIGPIPE */
1678 signal(SIGPIPE, SIG_IGN);
1680 /* Get a connection, either from inetd or a listening TCP socket */
1682 server_accept_inetd(&sock_in, &sock_out);
1686 if (options.protocol & SSH_PROTO_1)
1687 generate_ephemeral_server_key();
1689 signal(SIGHUP, sighup_handler);
1690 signal(SIGCHLD, main_sigchld_handler);
1691 signal(SIGTERM, sigterm_handler);
1692 signal(SIGQUIT, sigterm_handler);
1695 * Write out the pid file after the sigterm handler
1696 * is setup and the listen sockets are bound
1699 FILE *f = fopen(options.pid_file, "w");
1702 error("Couldn't create pid file \"%s\": %s",
1703 options.pid_file, strerror(errno));
1705 fprintf(f, "%ld\n", (long) getpid());
1710 /* Accept a connection and return in a forked child */
1711 server_accept_loop(&sock_in, &sock_out,
1712 &newsock, config_s);
1715 /* This is the child processing a new connection. */
1716 setproctitle("%s", "[accepted]");
1719 * Create a new session and process group since the 4.4BSD
1720 * setlogin() affects the entire process group. We don't
1721 * want the child to be able to affect the parent.
1723 #if !defined(SSHD_ACQUIRES_CTTY)
1725 * If setsid is called, on some platforms sshd will later acquire a
1726 * controlling terminal which will result in "could not set
1727 * controlling tty" errors.
1729 if (!debug_flag && !inetd_flag && setsid() < 0)
1730 error("setsid: %.100s", strerror(errno));
1736 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1737 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1738 dup2(newsock, STDIN_FILENO);
1739 dup2(STDIN_FILENO, STDOUT_FILENO);
1740 if (startup_pipe == -1)
1741 close(REEXEC_STARTUP_PIPE_FD);
1743 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1745 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1747 if (startup_pipe != -1)
1748 close(startup_pipe);
1750 execv(rexec_argv[0], rexec_argv);
1752 /* Reexec has failed, fall back and continue */
1753 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1754 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1755 log_init(__progname, options.log_level,
1756 options.log_facility, log_stderr);
1759 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1761 close(REEXEC_CONFIG_PASS_FD);
1762 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1763 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1764 dup2(fd, STDIN_FILENO);
1765 dup2(fd, STDOUT_FILENO);
1766 if (fd > STDERR_FILENO)
1769 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1770 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1774 * Disable the key regeneration alarm. We will not regenerate the
1775 * key since we are no longer in a position to give it to anyone. We
1776 * will not restart on SIGHUP since it no longer makes sense.
1779 signal(SIGALRM, SIG_DFL);
1780 signal(SIGHUP, SIG_DFL);
1781 signal(SIGTERM, SIG_DFL);
1782 signal(SIGQUIT, SIG_DFL);
1783 signal(SIGCHLD, SIG_DFL);
1784 signal(SIGINT, SIG_DFL);
1787 * Register our connection. This turns encryption off because we do
1790 packet_set_connection(sock_in, sock_out);
1791 packet_set_server();
1793 /* Set SO_KEEPALIVE if requested. */
1794 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1795 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1796 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1798 if ((remote_port = get_remote_port()) < 0) {
1799 debug("get_remote_port failed");
1803 /* set the HPN options for the child */
1804 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1807 * We use get_canonical_hostname with usedns = 0 instead of
1808 * get_remote_ipaddr here so IP options will be checked.
1810 (void) get_canonical_hostname(0);
1812 * The rest of the code depends on the fact that
1813 * get_remote_ipaddr() caches the remote ip, even if
1814 * the socket goes away.
1816 remote_ip = get_remote_ipaddr();
1818 #ifdef SSH_AUDIT_EVENTS
1819 audit_connection_from(remote_ip, remote_port);
1822 allow_severity = options.log_facility|LOG_INFO;
1823 deny_severity = options.log_facility|LOG_WARNING;
1824 /* Check whether logins are denied from this host. */
1825 if (packet_connection_is_on_socket()) {
1826 struct request_info req;
1828 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1831 if (!hosts_access(&req)) {
1832 debug("Connection refused by tcp wrapper");
1835 fatal("libwrap refuse returns");
1838 #endif /* LIBWRAP */
1840 /* Log the connection. */
1841 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1843 #ifdef USE_SECURITY_SESSION_API
1845 * Create a new security session for use by the new user login if
1846 * the current session is the root session or we are not launched
1847 * by inetd (eg: debugging mode or server mode). We do not
1848 * necessarily need to create a session if we are launched from
1849 * inetd because Panther xinetd will create a session for us.
1851 * The only case where this logic will fail is if there is an
1852 * inetd running in a non-root session which is not creating
1853 * new sessions for us. Then all the users will end up in the
1854 * same session (bad).
1856 * When the client exits, the session will be destroyed for us
1859 * We must create the session before any credentials are stored
1860 * (including AFS pags, which happens a few lines below).
1864 SecuritySessionId sid = 0;
1865 SessionAttributeBits sattrs = 0;
1867 err = SessionGetInfo(callerSecuritySession, &sid, &sattrs);
1869 error("SessionGetInfo() failed with error %.8X",
1872 debug("Current Session ID is %.8X / Session Attributes are %.8X",
1873 (unsigned) sid, (unsigned) sattrs);
1875 if (inetd_flag && !(sattrs & sessionIsRoot))
1876 debug("Running in inetd mode in a non-root session... "
1877 "assuming inetd created the session for us.");
1879 debug("Creating new security session...");
1880 err = SessionCreate(0, sessionHasTTY | sessionIsRemote);
1882 error("SessionCreate() failed with error %.8X",
1885 err = SessionGetInfo(callerSecuritySession, &sid,
1888 error("SessionGetInfo() failed with error %.8X",
1891 debug("New Session ID is %.8X / Session Attributes are %.8X",
1892 (unsigned) sid, (unsigned) sattrs);
1898 * We don't want to listen forever unless the other side
1899 * successfully authenticates itself. So we set up an alarm which is
1900 * cleared after successful authentication. A limit of zero
1901 * indicates no limit. Note that we don't set the alarm in debugging
1902 * mode; it is just annoying to have the server exit just when you
1903 * are about to discover the bug.
1905 signal(SIGALRM, grace_alarm_handler);
1907 alarm(options.login_grace_time);
1909 sshd_exchange_identification(sock_in, sock_out);
1910 #if defined(AFS_KRB5)
1911 /* If machine has AFS, set process authentication group. */
1916 #endif /* AFS || AFS_KRB5 */
1918 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1919 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1920 generate_ephemeral_server_key();
1922 packet_set_nonblocking();
1924 /* allocate authentication context */
1925 authctxt = xcalloc(1, sizeof(*authctxt));
1927 authctxt->loginmsg = &loginmsg;
1929 /* XXX global for cleanup, access from other modules */
1930 the_authctxt = authctxt;
1932 /* prepare buffer to collect messages to display to user after login */
1933 buffer_init(&loginmsg);
1936 if (privsep_preauth(authctxt) == 1)
1939 /* perform the key exchange */
1940 /* authenticate user and start session */
1943 do_authentication2(authctxt);
1946 do_authentication(authctxt);
1949 * If we use privilege separation, the unprivileged child transfers
1950 * the current keystate and exits
1953 mm_send_keystate(pmonitor);
1959 * Cancel the alarm we set to limit the time taken for
1963 signal(SIGALRM, SIG_DFL);
1964 authctxt->authenticated = 1;
1965 if (startup_pipe != -1) {
1966 close(startup_pipe);
1970 #ifdef SSH_AUDIT_EVENTS
1971 audit_event(SSH_AUTH_SUCCESS);
1975 if (options.gss_authentication && options.gss_deleg_creds) {
1976 temporarily_use_uid(authctxt->pw);
1977 ssh_gssapi_storecreds();
1982 if (options.use_pam) {
1989 * In privilege separation, we fork another child and prepare
1990 * file descriptor passing.
1993 privsep_postauth(authctxt);
1994 /* the monitor process [priv] will not return */
1996 destroy_sensitive_data();
1999 packet_set_timeout(options.client_alive_interval,
2000 options.client_alive_count_max);
2002 /* Start session. */
2003 do_authenticated(authctxt);
2005 /* The connection has been terminated. */
2006 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2007 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2008 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
2010 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2013 if (options.use_pam)
2015 #endif /* USE_PAM */
2017 #ifdef SSH_AUDIT_EVENTS
2018 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2030 * Decrypt session_key_int using our private server key and private host key
2031 * (key with larger modulus first).
2034 ssh1_session_key(BIGNUM *session_key_int)
2038 if (BN_cmp(sensitive_data.server_key->rsa->n,
2039 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2040 /* Server key has bigger modulus. */
2041 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2042 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2043 SSH_KEY_BITS_RESERVED) {
2044 fatal("do_connection: %s: "
2045 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2046 get_remote_ipaddr(),
2047 BN_num_bits(sensitive_data.server_key->rsa->n),
2048 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2049 SSH_KEY_BITS_RESERVED);
2051 if (rsa_private_decrypt(session_key_int, session_key_int,
2052 sensitive_data.server_key->rsa) <= 0)
2054 if (rsa_private_decrypt(session_key_int, session_key_int,
2055 sensitive_data.ssh1_host_key->rsa) <= 0)
2058 /* Host key has bigger modulus (or they are equal). */
2059 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2060 BN_num_bits(sensitive_data.server_key->rsa->n) +
2061 SSH_KEY_BITS_RESERVED) {
2062 fatal("do_connection: %s: "
2063 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2064 get_remote_ipaddr(),
2065 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2066 BN_num_bits(sensitive_data.server_key->rsa->n),
2067 SSH_KEY_BITS_RESERVED);
2069 if (rsa_private_decrypt(session_key_int, session_key_int,
2070 sensitive_data.ssh1_host_key->rsa) < 0)
2072 if (rsa_private_decrypt(session_key_int, session_key_int,
2073 sensitive_data.server_key->rsa) < 0)
2086 BIGNUM *session_key_int;
2087 u_char session_key[SSH_SESSION_KEY_LENGTH];
2089 u_int cipher_type, auth_mask, protocol_flags;
2092 * Generate check bytes that the client must send back in the user
2093 * packet in order for it to be accepted; this is used to defy ip
2094 * spoofing attacks. Note that this only works against somebody
2095 * doing IP spoofing from a remote machine; any machine on the local
2096 * network can still see outgoing packets and catch the random
2097 * cookie. This only affects rhosts authentication, and this is one
2098 * of the reasons why it is inherently insecure.
2100 arc4random_buf(cookie, sizeof(cookie));
2103 * Send our public key. We include in the packet 64 bits of random
2104 * data that must be matched in the reply in order to prevent IP
2107 packet_start(SSH_SMSG_PUBLIC_KEY);
2108 for (i = 0; i < 8; i++)
2109 packet_put_char(cookie[i]);
2111 /* Store our public server RSA key. */
2112 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2113 packet_put_bignum(sensitive_data.server_key->rsa->e);
2114 packet_put_bignum(sensitive_data.server_key->rsa->n);
2116 /* Store our public host RSA key. */
2117 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2118 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2119 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2121 /* Put protocol flags. */
2122 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2124 /* Declare which ciphers we support. */
2125 packet_put_int(cipher_mask_ssh1(0));
2127 /* Declare supported authentication types. */
2129 if (options.rhosts_rsa_authentication)
2130 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2131 if (options.rsa_authentication)
2132 auth_mask |= 1 << SSH_AUTH_RSA;
2133 if (options.challenge_response_authentication == 1)
2134 auth_mask |= 1 << SSH_AUTH_TIS;
2135 if (options.password_authentication)
2136 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2137 packet_put_int(auth_mask);
2139 /* Send the packet and wait for it to be sent. */
2141 packet_write_wait();
2143 debug("Sent %d bit server key and %d bit host key.",
2144 BN_num_bits(sensitive_data.server_key->rsa->n),
2145 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2147 /* Read clients reply (cipher type and session key). */
2148 packet_read_expect(SSH_CMSG_SESSION_KEY);
2150 /* Get cipher type and check whether we accept this. */
2151 cipher_type = packet_get_char();
2153 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2154 packet_disconnect("Warning: client selects unsupported cipher.");
2156 /* Get check bytes from the packet. These must match those we
2157 sent earlier with the public key packet. */
2158 for (i = 0; i < 8; i++)
2159 if (cookie[i] != packet_get_char())
2160 packet_disconnect("IP Spoofing check bytes do not match.");
2162 debug("Encryption type: %.200s", cipher_name(cipher_type));
2164 /* Get the encrypted integer. */
2165 if ((session_key_int = BN_new()) == NULL)
2166 fatal("do_ssh1_kex: BN_new failed");
2167 packet_get_bignum(session_key_int);
2169 protocol_flags = packet_get_int();
2170 packet_set_protocol_flags(protocol_flags);
2173 /* Decrypt session_key_int using host/server keys */
2174 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2177 * Extract session key from the decrypted integer. The key is in the
2178 * least significant 256 bits of the integer; the first byte of the
2179 * key is in the highest bits.
2182 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2183 len = BN_num_bytes(session_key_int);
2184 if (len < 0 || (u_int)len > sizeof(session_key)) {
2185 error("do_ssh1_kex: bad session key len from %s: "
2186 "session_key_int %d > sizeof(session_key) %lu",
2187 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2190 memset(session_key, 0, sizeof(session_key));
2191 BN_bn2bin(session_key_int,
2192 session_key + sizeof(session_key) - len);
2194 derive_ssh1_session_id(
2195 sensitive_data.ssh1_host_key->rsa->n,
2196 sensitive_data.server_key->rsa->n,
2197 cookie, session_id);
2199 * Xor the first 16 bytes of the session key with the
2202 for (i = 0; i < 16; i++)
2203 session_key[i] ^= session_id[i];
2207 int bytes = BN_num_bytes(session_key_int);
2208 u_char *buf = xmalloc(bytes);
2211 logit("do_connection: generating a fake encryption key");
2212 BN_bn2bin(session_key_int, buf);
2214 MD5_Update(&md, buf, bytes);
2215 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2216 MD5_Final(session_key, &md);
2218 MD5_Update(&md, session_key, 16);
2219 MD5_Update(&md, buf, bytes);
2220 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2221 MD5_Final(session_key + 16, &md);
2222 memset(buf, 0, bytes);
2224 for (i = 0; i < 16; i++)
2225 session_id[i] = session_key[i] ^ session_key[i + 16];
2227 /* Destroy the private and public keys. No longer. */
2228 destroy_sensitive_data();
2231 mm_ssh1_session_id(session_id);
2233 /* Destroy the decrypted integer. It is no longer needed. */
2234 BN_clear_free(session_key_int);
2236 /* Set the session key. From this on all communications will be encrypted. */
2237 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2239 /* Destroy our copy of the session key. It is no longer needed. */
2240 memset(session_key, 0, sizeof(session_key));
2242 debug("Received session key; encryption turned on.");
2244 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2245 packet_start(SSH_SMSG_SUCCESS);
2247 packet_write_wait();
2251 * SSH2 key exchange: diffie-hellman-group1-sha1
2259 debug ("MYFLAG IS %d", myflag);
2260 if (options.ciphers != NULL) {
2261 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2262 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2263 } else if (options.none_enabled == 1) {
2264 debug ("WARNING: None cipher enabled");
2265 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2266 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE;
2268 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2269 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2270 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2271 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2273 if (options.macs != NULL) {
2274 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2275 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2277 if (options.compression == COMP_NONE) {
2278 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2279 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2280 } else if (options.compression == COMP_DELAYED) {
2281 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2282 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2285 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2291 char *newstr = NULL;
2292 orig = myproposal[PROPOSAL_KEX_ALGS];
2295 * If we don't have a host key, then there's no point advertising
2296 * the other key exchange algorithms
2299 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
2302 if (options.gss_keyex)
2303 gss = ssh_gssapi_server_mechanisms();
2308 xasprintf(&newstr, "%s,%s", gss, orig);
2315 * If we've got GSSAPI mechanisms, then we've got the 'null' host
2316 * key alg, but we can't tell people about it unless its the only
2317 * host key algorithm we support
2319 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
2320 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
2323 myproposal[PROPOSAL_KEX_ALGS] = newstr;
2325 fatal("No supported key exchange algorithms");
2329 /* start key exchange */
2330 kex = kex_setup(myproposal);
2331 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2332 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2333 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2334 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2336 if (options.gss_keyex) {
2337 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
2338 kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
2339 kex->kex[KEX_GSS_GEX_SHA1] = kexgss_server;
2343 kex->client_version_string=client_version_string;
2344 kex->server_version_string=server_version_string;
2345 kex->load_host_key=&get_hostkey_by_type;
2346 kex->host_key_index=&get_hostkey_index;
2350 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2352 session_id2 = kex->session_id;
2353 session_id2_len = kex->session_id_len;
2356 /* send 1st encrypted/maced/compressed message */
2357 packet_start(SSH2_MSG_IGNORE);
2358 packet_put_cstring("markus");
2360 packet_write_wait();
2365 /* server specific fatal cleanup */
2370 do_cleanup(the_authctxt);
2371 #ifdef SSH_AUDIT_EVENTS
2372 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2373 if (!use_privsep || mm_is_monitor())
2374 audit_event(SSH_CONNECTION_ABANDON);