1 /* $OpenBSD: sshd.c,v 1.347 2006/08/18 09:15:20 markus 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"
74 #include <openssl/dh.h>
75 #include <openssl/bn.h>
76 #include <openssl/md5.h>
77 #include <openssl/rand.h>
78 #ifdef HAVE_SECUREWARE
79 #include <sys/security.h>
99 #include "myproposal.h"
100 #include "authfile.h"
101 #include "pathnames.h"
102 #include "atomicio.h"
103 #include "canohost.h"
104 #include "hostfile.h"
108 #include "dispatch.h"
109 #include "channels.h"
111 #include "monitor_mm.h"
116 #include "monitor_wrap.h"
117 #include "monitor_fdpass.h"
120 #ifdef USE_SECURITY_SESSION_API
121 #include <Security/AuthSession.h>
127 int allow_severity = LOG_INFO;
128 int deny_severity = LOG_WARNING;
136 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
137 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
138 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
139 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
141 extern char *__progname;
143 /* Server configuration options. */
144 ServerOptions options;
146 /* Name of the server configuration file. */
147 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
150 * Debug mode flag. This can be set on the command line. If debug
151 * mode is enabled, extra debugging output will be sent to the system
152 * log, the daemon will not go to background, and will exit after processing
153 * the first connection.
157 /* Flag indicating that the daemon should only test the configuration and keys. */
160 /* Flag indicating that the daemon is being started from inetd. */
163 /* Flag indicating that sshd should not detach and become a daemon. */
164 int no_daemon_flag = 0;
166 /* debug goes to stderr unless inetd_flag is set */
169 /* Saved arguments to main(). */
174 int rexeced_flag = 0;
180 * The sockets that the server is listening; this is used in the SIGHUP
183 #define MAX_LISTEN_SOCKS 16
184 int listen_socks[MAX_LISTEN_SOCKS];
185 int num_listen_socks = 0;
188 * the client's version string, passed by sshd2 in compat mode. if != NULL,
189 * sshd will skip the version-number exchange
191 char *client_version_string = NULL;
192 char *server_version_string = NULL;
194 /* for rekeying XXX fixme */
198 * Any really sensitive data in the application is contained in this
199 * structure. The idea is that this structure could be locked into memory so
200 * that the pages do not get written into swap. However, there are some
201 * problems. The private key contains BIGNUMs, and we do not (in principle)
202 * have access to the internals of them, and locking just the structure is
203 * not very useful. Currently, memory locking is not implemented.
206 Key *server_key; /* ephemeral server key */
207 Key *ssh1_host_key; /* ssh1 host key */
208 Key **host_keys; /* all private host keys */
211 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
215 * Flag indicating whether the RSA server key needs to be regenerated.
216 * Is set in the SIGALRM handler and cleared when the key is regenerated.
218 static volatile sig_atomic_t key_do_regen = 0;
220 /* This is set to true when a signal is received. */
221 static volatile sig_atomic_t received_sighup = 0;
222 static volatile sig_atomic_t received_sigterm = 0;
224 /* session identifier, used by RSA-auth */
225 u_char session_id[16];
228 u_char *session_id2 = NULL;
229 u_int session_id2_len = 0;
231 /* record remote hostname or ip */
232 u_int utmp_len = MAXHOSTNAMELEN;
234 /* options.max_startup sized array of fd ints */
235 int *startup_pipes = NULL;
236 int startup_pipe; /* in child */
238 /* variables used for privilege separation */
239 int use_privsep = -1;
240 struct monitor *pmonitor = NULL;
242 /* global authentication context */
243 Authctxt *the_authctxt = NULL;
245 /* sshd_config buffer */
248 /* message to be displayed after login */
251 /* Unprivileged user */
252 struct passwd *privsep_pw = NULL;
254 /* Prototypes for various functions defined later in this file. */
255 void destroy_sensitive_data(void);
256 void demote_sensitive_data(void);
258 static void do_ssh1_kex(void);
259 static void do_ssh2_kex(void);
262 * Close all listening sockets
265 close_listen_socks(void)
269 for (i = 0; i < num_listen_socks; i++)
270 close(listen_socks[i]);
271 num_listen_socks = -1;
275 close_startup_pipes(void)
280 for (i = 0; i < options.max_startups; i++)
281 if (startup_pipes[i] != -1)
282 close(startup_pipes[i]);
286 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
287 * the effect is to reread the configuration file (and to regenerate
293 sighup_handler(int sig)
295 int save_errno = errno;
298 signal(SIGHUP, sighup_handler);
303 * Called from the main program after receiving SIGHUP.
304 * Restarts the server.
309 logit("Received SIGHUP; restarting.");
310 close_listen_socks();
311 close_startup_pipes();
312 execv(saved_argv[0], saved_argv);
313 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
319 * Generic signal handler for terminating signals in the master daemon.
323 sigterm_handler(int sig)
325 received_sigterm = sig;
329 * SIGCHLD handler. This is called whenever a child dies. This will then
330 * reap any zombies left by exited children.
334 main_sigchld_handler(int sig)
336 int save_errno = errno;
340 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
341 (pid < 0 && errno == EINTR))
344 signal(SIGCHLD, main_sigchld_handler);
349 * Signal handler for the alarm after the login grace period has expired.
353 grace_alarm_handler(int sig)
355 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
356 kill(pmonitor->m_pid, SIGALRM);
358 /* Log error and exit. */
359 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
363 * Signal handler for the key regeneration alarm. Note that this
364 * alarm only occurs in the daemon waiting for connections, and it does not
365 * do anything with the private key or random state before forking.
366 * Thus there should be no concurrency control/asynchronous execution
370 generate_ephemeral_server_key(void)
375 verbose("Generating %s%d bit RSA key.",
376 sensitive_data.server_key ? "new " : "", options.server_key_bits);
377 if (sensitive_data.server_key != NULL)
378 key_free(sensitive_data.server_key);
379 sensitive_data.server_key = key_generate(KEY_RSA1,
380 options.server_key_bits);
381 verbose("RSA key generation complete.");
383 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
386 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
394 key_regeneration_alarm(int sig)
396 int save_errno = errno;
398 signal(SIGALRM, SIG_DFL);
404 sshd_exchange_identification(int sock_in, int sock_out)
408 int remote_major, remote_minor;
411 char buf[256]; /* Must not be larger than remote_version. */
412 char remote_version[256]; /* Must be at least as big as buf. */
414 if ((options.protocol & SSH_PROTO_1) &&
415 (options.protocol & SSH_PROTO_2)) {
416 major = PROTOCOL_MAJOR_1;
418 } else if (options.protocol & SSH_PROTO_2) {
419 major = PROTOCOL_MAJOR_2;
420 minor = PROTOCOL_MINOR_2;
422 major = PROTOCOL_MAJOR_1;
423 minor = PROTOCOL_MINOR_1;
425 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
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);
477 compat_datafellows(remote_version);
479 if (datafellows & SSH_BUG_PROBE) {
480 logit("probed from %s with %s. Don't panic.",
481 get_remote_ipaddr(), client_version_string);
485 if (datafellows & SSH_BUG_SCANNER) {
486 logit("scanned from %s with %s. Don't panic.",
487 get_remote_ipaddr(), client_version_string);
492 switch (remote_major) {
494 if (remote_minor == 99) {
495 if (options.protocol & SSH_PROTO_2)
501 if (!(options.protocol & SSH_PROTO_1)) {
505 if (remote_minor < 3) {
506 packet_disconnect("Your ssh version is too old and "
507 "is no longer supported. Please install a newer version.");
508 } else if (remote_minor == 3) {
509 /* note that this disables agent-forwarding */
514 if (options.protocol & SSH_PROTO_2) {
523 chop(server_version_string);
524 debug("Local version string %.200s", server_version_string);
527 s = "Protocol major versions differ.\n";
528 (void) atomicio(vwrite, sock_out, s, strlen(s));
531 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
533 server_version_string, client_version_string);
538 /* Destroy the host and server keys. They will no longer be needed. */
540 destroy_sensitive_data(void)
544 if (sensitive_data.server_key) {
545 key_free(sensitive_data.server_key);
546 sensitive_data.server_key = NULL;
548 for (i = 0; i < options.num_host_key_files; i++) {
549 if (sensitive_data.host_keys[i]) {
550 key_free(sensitive_data.host_keys[i]);
551 sensitive_data.host_keys[i] = NULL;
554 sensitive_data.ssh1_host_key = NULL;
555 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
558 /* Demote private to public keys for network child */
560 demote_sensitive_data(void)
565 if (sensitive_data.server_key) {
566 tmp = key_demote(sensitive_data.server_key);
567 key_free(sensitive_data.server_key);
568 sensitive_data.server_key = tmp;
571 for (i = 0; i < options.num_host_key_files; i++) {
572 if (sensitive_data.host_keys[i]) {
573 tmp = key_demote(sensitive_data.host_keys[i]);
574 key_free(sensitive_data.host_keys[i]);
575 sensitive_data.host_keys[i] = tmp;
576 if (tmp->type == KEY_RSA1)
577 sensitive_data.ssh1_host_key = tmp;
581 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
585 privsep_preauth_child(void)
591 /* Enable challenge-response authentication for privilege separation */
592 privsep_challenge_enable();
594 for (i = 0; i < 256; i++)
595 rnd[i] = arc4random();
596 RAND_seed(rnd, sizeof(rnd));
598 /* Demote the private keys to public keys. */
599 demote_sensitive_data();
601 /* Change our root directory */
602 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
603 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
605 if (chdir("/") == -1)
606 fatal("chdir(\"/\"): %s", strerror(errno));
608 /* Drop our privileges */
609 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
610 (u_int)privsep_pw->pw_gid);
612 /* XXX not ready, too heavy after chroot */
613 do_setusercontext(privsep_pw);
615 gidset[0] = privsep_pw->pw_gid;
616 if (setgroups(1, gidset) < 0)
617 fatal("setgroups: %.100s", strerror(errno));
618 permanently_set_uid(privsep_pw);
623 privsep_preauth(Authctxt *authctxt)
628 /* Set up unprivileged child process to deal with network data */
629 pmonitor = monitor_init();
630 /* Store a pointer to the kex for later rekeying */
631 pmonitor->m_pkex = &xxx_kex;
635 fatal("fork of unprivileged child failed");
636 } else if (pid != 0) {
637 debug2("Network child is on pid %ld", (long)pid);
639 close(pmonitor->m_recvfd);
640 pmonitor->m_pid = pid;
641 monitor_child_preauth(authctxt, pmonitor);
642 close(pmonitor->m_sendfd);
645 monitor_sync(pmonitor);
647 /* Wait for the child's exit status */
648 while (waitpid(pid, &status, 0) < 0)
655 close(pmonitor->m_sendfd);
657 /* Demote the child */
658 if (getuid() == 0 || geteuid() == 0)
659 privsep_preauth_child();
660 setproctitle("%s", "[net]");
666 privsep_postauth(Authctxt *authctxt)
668 #ifdef DISABLE_FD_PASSING
671 if (authctxt->pw->pw_uid == 0 || options.use_login) {
673 /* File descriptor passing is broken or root login */
678 /* New socket pair */
679 monitor_reinit(pmonitor);
681 pmonitor->m_pid = fork();
682 if (pmonitor->m_pid == -1)
683 fatal("fork of unprivileged child failed");
684 else if (pmonitor->m_pid != 0) {
685 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
686 close(pmonitor->m_recvfd);
687 buffer_clear(&loginmsg);
688 monitor_child_postauth(pmonitor);
694 close(pmonitor->m_sendfd);
696 /* Demote the private keys to public keys. */
697 demote_sensitive_data();
699 /* Drop privileges */
700 do_setusercontext(authctxt->pw);
703 /* It is safe now to apply the key state */
704 monitor_apply_keystate(pmonitor);
707 * Tell the packet layer that authentication was successful, since
708 * this information is not part of the key state.
710 packet_set_authenticated();
714 list_hostkey_types(void)
722 for (i = 0; i < options.num_host_key_files; i++) {
723 Key *key = sensitive_data.host_keys[i];
729 if (buffer_len(&b) > 0)
730 buffer_append(&b, ",", 1);
731 p = key_ssh_name(key);
732 buffer_append(&b, p, strlen(p));
736 buffer_append(&b, "\0", 1);
737 ret = xstrdup(buffer_ptr(&b));
739 debug("list_hostkey_types: %s", ret);
744 get_hostkey_by_type(int type)
748 for (i = 0; i < options.num_host_key_files; i++) {
749 Key *key = sensitive_data.host_keys[i];
750 if (key != NULL && key->type == type)
757 get_hostkey_by_index(int ind)
759 if (ind < 0 || ind >= options.num_host_key_files)
761 return (sensitive_data.host_keys[ind]);
765 get_hostkey_index(Key *key)
769 for (i = 0; i < options.num_host_key_files; i++) {
770 if (key == sensitive_data.host_keys[i])
777 * returns 1 if connection should be dropped, 0 otherwise.
778 * dropping starts at connection #max_startups_begin with a probability
779 * of (max_startups_rate/100). the probability increases linearly until
780 * all connections are dropped for startups > max_startups
783 drop_connection(int startups)
787 if (startups < options.max_startups_begin)
789 if (startups >= options.max_startups)
791 if (options.max_startups_rate == 100)
794 p = 100 - options.max_startups_rate;
795 p *= startups - options.max_startups_begin;
796 p /= options.max_startups - options.max_startups_begin;
797 p += options.max_startups_rate;
798 r = arc4random() % 100;
800 debug("drop_connection: p %d, r %d", p, r);
801 return (r < p) ? 1 : 0;
807 fprintf(stderr, "%s, %s\n",
808 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
810 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
811 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
817 send_rexec_state(int fd, Buffer *conf)
821 debug3("%s: entering fd = %d config len %d", __func__, fd,
825 * Protocol from reexec master to child:
826 * string configuration
827 * u_int ephemeral_key_follows
828 * bignum e (only if ephemeral_key_follows == 1)
834 * string rngseed (only if OpenSSL is not self-seeded)
837 buffer_put_cstring(&m, buffer_ptr(conf));
839 if (sensitive_data.server_key != NULL &&
840 sensitive_data.server_key->type == KEY_RSA1) {
841 buffer_put_int(&m, 1);
842 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
843 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
844 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
845 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
846 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
847 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
849 buffer_put_int(&m, 0);
851 #ifndef OPENSSL_PRNG_ONLY
852 rexec_send_rng_seed(&m);
855 if (ssh_msg_send(fd, 0, &m) == -1)
856 fatal("%s: ssh_msg_send failed", __func__);
860 debug3("%s: done", __func__);
864 recv_rexec_state(int fd, Buffer *conf)
870 debug3("%s: entering fd = %d", __func__, fd);
874 if (ssh_msg_recv(fd, &m) == -1)
875 fatal("%s: ssh_msg_recv failed", __func__);
876 if (buffer_get_char(&m) != 0)
877 fatal("%s: rexec version mismatch", __func__);
879 cp = buffer_get_string(&m, &len);
881 buffer_append(conf, cp, len + 1);
884 if (buffer_get_int(&m)) {
885 if (sensitive_data.server_key != NULL)
886 key_free(sensitive_data.server_key);
887 sensitive_data.server_key = key_new_private(KEY_RSA1);
888 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
889 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
890 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
891 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
892 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
893 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
894 rsa_generate_additional_parameters(
895 sensitive_data.server_key->rsa);
898 #ifndef OPENSSL_PRNG_ONLY
899 rexec_recv_rng_seed(&m);
904 debug3("%s: done", __func__);
907 /* Accept a connection from inetd */
909 server_accept_inetd(int *sock_in, int *sock_out)
915 close(REEXEC_CONFIG_PASS_FD);
916 *sock_in = *sock_out = dup(STDIN_FILENO);
918 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
919 close(REEXEC_STARTUP_PIPE_FD);
922 *sock_in = dup(STDIN_FILENO);
923 *sock_out = dup(STDOUT_FILENO);
926 * We intentionally do not close the descriptors 0, 1, and 2
927 * as our code for setting the descriptors won't work if
928 * ttyfd happens to be one of those.
930 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
931 dup2(fd, STDIN_FILENO);
932 dup2(fd, STDOUT_FILENO);
933 if (fd > STDOUT_FILENO)
936 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
940 * Listen for TCP connections
945 int ret, listen_sock, on = 1;
947 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
949 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
950 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
952 if (num_listen_socks >= MAX_LISTEN_SOCKS)
953 fatal("Too many listen sockets. "
954 "Enlarge MAX_LISTEN_SOCKS");
955 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
956 ntop, sizeof(ntop), strport, sizeof(strport),
957 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
958 error("getnameinfo failed: %.100s",
959 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
963 /* Create socket for listening. */
964 listen_sock = socket(ai->ai_family, ai->ai_socktype,
966 if (listen_sock < 0) {
967 /* kernel may not support ipv6 */
968 verbose("socket: %.100s", strerror(errno));
971 if (set_nonblock(listen_sock) == -1) {
976 * Set socket options.
977 * Allow local port reuse in TIME_WAIT.
979 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
980 &on, sizeof(on)) == -1)
981 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
983 debug("Bind to port %s on %s.", strport, ntop);
985 /* Bind the socket to the desired port. */
986 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
987 error("Bind to port %s on %s failed: %.200s.",
988 strport, ntop, strerror(errno));
992 listen_socks[num_listen_socks] = listen_sock;
995 /* Start listening on the port. */
996 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
997 fatal("listen on [%s]:%s: %.100s",
998 ntop, strport, strerror(errno));
999 logit("Server listening on %s port %s.", ntop, strport);
1001 freeaddrinfo(options.listen_addrs);
1003 if (!num_listen_socks)
1004 fatal("Cannot bind any address.");
1008 * The main TCP accept loop. Note that, for the non-debug case, returns
1009 * from this function are in a forked subprocess.
1012 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1015 int i, j, ret, maxfd;
1016 int key_used = 0, startups = 0;
1017 int startup_p[2] = { -1 , -1 };
1018 struct sockaddr_storage from;
1022 /* setup fd set for accept */
1025 for (i = 0; i < num_listen_socks; i++)
1026 if (listen_socks[i] > maxfd)
1027 maxfd = listen_socks[i];
1028 /* pipes connected to unauthenticated childs */
1029 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1030 for (i = 0; i < options.max_startups; i++)
1031 startup_pipes[i] = -1;
1034 * Stay listening for connections until the system crashes or
1035 * the daemon is killed with a signal.
1038 if (received_sighup)
1042 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1045 for (i = 0; i < num_listen_socks; i++)
1046 FD_SET(listen_socks[i], fdset);
1047 for (i = 0; i < options.max_startups; i++)
1048 if (startup_pipes[i] != -1)
1049 FD_SET(startup_pipes[i], fdset);
1051 /* Wait in select until there is a connection. */
1052 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1053 if (ret < 0 && errno != EINTR)
1054 error("select: %.100s", strerror(errno));
1055 if (received_sigterm) {
1056 logit("Received signal %d; terminating.",
1057 (int) received_sigterm);
1058 close_listen_socks();
1059 unlink(options.pid_file);
1062 if (key_used && key_do_regen) {
1063 generate_ephemeral_server_key();
1070 for (i = 0; i < options.max_startups; i++)
1071 if (startup_pipes[i] != -1 &&
1072 FD_ISSET(startup_pipes[i], fdset)) {
1074 * the read end of the pipe is ready
1075 * if the child has closed the pipe
1076 * after successful authentication
1077 * or if the child has died
1079 close(startup_pipes[i]);
1080 startup_pipes[i] = -1;
1083 for (i = 0; i < num_listen_socks; i++) {
1084 if (!FD_ISSET(listen_socks[i], fdset))
1086 fromlen = sizeof(from);
1087 *newsock = accept(listen_socks[i],
1088 (struct sockaddr *)&from, &fromlen);
1090 if (errno != EINTR && errno != EWOULDBLOCK)
1091 error("accept: %.100s", strerror(errno));
1094 if (unset_nonblock(*newsock) == -1) {
1098 if (drop_connection(startups) == 1) {
1099 debug("drop connection #%d", startups);
1103 if (pipe(startup_p) == -1) {
1108 if (rexec_flag && socketpair(AF_UNIX,
1109 SOCK_STREAM, 0, config_s) == -1) {
1110 error("reexec socketpair: %s",
1113 close(startup_p[0]);
1114 close(startup_p[1]);
1118 for (j = 0; j < options.max_startups; j++)
1119 if (startup_pipes[j] == -1) {
1120 startup_pipes[j] = startup_p[0];
1121 if (maxfd < startup_p[0])
1122 maxfd = startup_p[0];
1128 * Got connection. Fork a child to handle it, unless
1129 * we are in debugging mode.
1133 * In debugging mode. Close the listening
1134 * socket, and start processing the
1135 * connection without forking.
1137 debug("Server will not fork when running in debugging mode.");
1138 close_listen_socks();
1139 *sock_in = *newsock;
1140 *sock_out = *newsock;
1141 close(startup_p[0]);
1142 close(startup_p[1]);
1146 send_rexec_state(config_s[0],
1154 * Normal production daemon. Fork, and have
1155 * the child process the connection. The
1156 * parent continues listening.
1158 platform_pre_fork();
1159 if ((pid = fork()) == 0) {
1161 * Child. Close the listening and
1162 * max_startup sockets. Start using
1163 * the accepted socket. Reinitialize
1164 * logging (since our pid has changed).
1165 * We break out of the loop to handle
1168 platform_post_fork_child();
1169 startup_pipe = startup_p[1];
1170 close_startup_pipes();
1171 close_listen_socks();
1172 *sock_in = *newsock;
1173 *sock_out = *newsock;
1174 log_init(__progname,
1176 options.log_facility,
1183 /* Parent. Stay in the loop. */
1184 platform_post_fork_parent(pid);
1186 error("fork: %.100s", strerror(errno));
1188 debug("Forked child %ld.", (long)pid);
1190 close(startup_p[1]);
1193 send_rexec_state(config_s[0], &cfg);
1199 * Mark that the key has been used (it
1200 * was "given" to the child).
1202 if ((options.protocol & SSH_PROTO_1) &&
1204 /* Schedule server key regeneration alarm. */
1205 signal(SIGALRM, key_regeneration_alarm);
1206 alarm(options.key_regeneration_time);
1213 * Ensure that our random state differs
1214 * from that of the child
1219 /* child process check (or debug mode) */
1220 if (num_listen_socks < 0)
1227 * Main program for the daemon.
1230 main(int ac, char **av)
1232 extern char *optarg;
1235 int sock_in = -1, sock_out = -1, newsock = -1;
1236 const char *remote_ip;
1239 int config_s[2] = { -1 , -1 };
1243 #ifdef HAVE_SECUREWARE
1244 (void)set_auth_parameters(ac, av);
1246 __progname = ssh_get_progname(av[0]);
1249 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1252 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1253 for (i = 0; i < ac; i++)
1254 saved_argv[i] = xstrdup(av[i]);
1255 saved_argv[i] = NULL;
1257 #ifndef HAVE_SETPROCTITLE
1258 /* Prepare for later setproctitle emulation */
1259 compat_init_setproctitle(ac, av);
1263 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1264 debug("setgroups(): %.200s", strerror(errno));
1266 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1269 /* Initialize configuration options to their default values. */
1270 initialize_server_options(&options);
1272 /* Parse command-line arguments. */
1273 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
1276 options.address_family = AF_INET;
1279 options.address_family = AF_INET6;
1282 config_file_name = optarg;
1285 if (debug_flag == 0) {
1287 options.log_level = SYSLOG_LEVEL_DEBUG1;
1288 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1289 options.log_level++;
1311 options.log_level = SYSLOG_LEVEL_QUIET;
1314 options.server_key_bits = (int)strtonum(optarg, 256,
1318 options.ports_from_cmdline = 1;
1319 if (options.num_ports >= MAX_PORTS) {
1320 fprintf(stderr, "too many ports.\n");
1323 options.ports[options.num_ports++] = a2port(optarg);
1324 if (options.ports[options.num_ports-1] == 0) {
1325 fprintf(stderr, "Bad port number.\n");
1330 if ((options.login_grace_time = convtime(optarg)) == -1) {
1331 fprintf(stderr, "Invalid login grace time.\n");
1336 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1337 fprintf(stderr, "Invalid key regeneration interval.\n");
1342 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1343 fprintf(stderr, "too many host keys.\n");
1346 options.host_key_files[options.num_host_key_files++] = optarg;
1352 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1353 if (utmp_len > MAXHOSTNAMELEN) {
1354 fprintf(stderr, "Invalid utmp length.\n");
1359 line = xstrdup(optarg);
1360 if (process_server_config_line(&options, line,
1361 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1371 if (rexeced_flag || inetd_flag)
1373 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1374 fatal("sshd re-exec requires execution with an absolute path");
1376 closefrom(REEXEC_MIN_FREE_FD);
1378 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1380 SSLeay_add_all_algorithms();
1383 * Force logging to stderr until we have loaded the private host
1384 * key (unless started from inetd)
1386 log_init(__progname,
1387 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1388 SYSLOG_LEVEL_INFO : options.log_level,
1389 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1390 SYSLOG_FACILITY_AUTH : options.log_facility,
1391 log_stderr || !inetd_flag);
1394 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1395 * root's environment
1397 if (getenv("KRB5CCNAME") != NULL)
1398 unsetenv("KRB5CCNAME");
1401 /* Cray can define user privs drop all privs now!
1402 * Not needed on PRIV_SU systems!
1407 sensitive_data.server_key = NULL;
1408 sensitive_data.ssh1_host_key = NULL;
1409 sensitive_data.have_ssh1_key = 0;
1410 sensitive_data.have_ssh2_key = 0;
1412 /* Fetch our configuration */
1415 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1417 load_server_config(config_file_name, &cfg);
1419 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1420 &cfg, NULL, NULL, NULL);
1424 /* Fill in default values for those options not explicitly set. */
1425 fill_default_server_options(&options);
1427 /* set default channel AF */
1428 channel_set_af(options.address_family);
1430 /* Check that there are no remaining arguments. */
1432 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1436 debug("sshd version %.100s", SSH_RELEASE);
1438 /* Store privilege separation user for later use */
1439 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1440 fatal("Privilege separation user %s does not exist",
1442 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1443 privsep_pw->pw_passwd = "*";
1444 privsep_pw = pwcopy(privsep_pw);
1447 /* load private host keys */
1448 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1450 for (i = 0; i < options.num_host_key_files; i++)
1451 sensitive_data.host_keys[i] = NULL;
1453 for (i = 0; i < options.num_host_key_files; i++) {
1454 key = key_load_private(options.host_key_files[i], "", NULL);
1455 sensitive_data.host_keys[i] = key;
1457 error("Could not load host key: %s",
1458 options.host_key_files[i]);
1459 sensitive_data.host_keys[i] = NULL;
1462 switch (key->type) {
1464 sensitive_data.ssh1_host_key = key;
1465 sensitive_data.have_ssh1_key = 1;
1469 sensitive_data.have_ssh2_key = 1;
1472 debug("private host key: #%d type %d %s", i, key->type,
1475 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1476 logit("Disabling protocol version 1. Could not load host key");
1477 options.protocol &= ~SSH_PROTO_1;
1480 /* The GSSAPI key exchange can run without a host key */
1481 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1482 logit("Disabling protocol version 2. Could not load host key");
1483 options.protocol &= ~SSH_PROTO_2;
1486 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1487 logit("sshd: no hostkeys available -- exiting.");
1491 /* Check certain values for sanity. */
1492 if (options.protocol & SSH_PROTO_1) {
1493 if (options.server_key_bits < 512 ||
1494 options.server_key_bits > 32768) {
1495 fprintf(stderr, "Bad server key size.\n");
1499 * Check that server and host key lengths differ sufficiently. This
1500 * is necessary to make double encryption work with rsaref. Oh, I
1501 * hate software patents. I dont know if this can go? Niels
1503 if (options.server_key_bits >
1504 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1505 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1506 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1507 SSH_KEY_BITS_RESERVED) {
1508 options.server_key_bits =
1509 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1510 SSH_KEY_BITS_RESERVED;
1511 debug("Forcing server key to %d bits to make it differ from host key.",
1512 options.server_key_bits);
1519 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1520 (S_ISDIR(st.st_mode) == 0))
1521 fatal("Missing privilege separation directory: %s",
1522 _PATH_PRIVSEP_CHROOT_DIR);
1525 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1526 (st.st_uid != getuid () ||
1527 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1529 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1531 fatal("%s must be owned by root and not group or "
1532 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1535 /* Configuration looks good, so exit if in test mode. */
1540 * Clear out any supplemental groups we may have inherited. This
1541 * prevents inadvertent creation of files with bad modes (in the
1542 * portable version at least, it's certainly possible for PAM
1543 * to create a file, and we can't control the code in every
1544 * module which might be used).
1546 if (setgroups(0, NULL) < 0)
1547 debug("setgroups() failed: %.200s", strerror(errno));
1550 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1551 for (i = 0; i < rexec_argc; i++) {
1552 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1553 rexec_argv[i] = saved_argv[i];
1555 rexec_argv[rexec_argc] = "-R";
1556 rexec_argv[rexec_argc + 1] = NULL;
1559 /* Initialize the log (it is reinitialized below in case we forked). */
1560 if (debug_flag && (!inetd_flag || rexeced_flag))
1562 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1565 * If not in debugging mode, and not started from inetd, disconnect
1566 * from the controlling terminal, and fork. The original process
1569 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1572 #endif /* TIOCNOTTY */
1573 if (daemon(0, 0) < 0)
1574 fatal("daemon() failed: %.200s", strerror(errno));
1576 /* Disconnect from the controlling tty. */
1578 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1580 (void) ioctl(fd, TIOCNOTTY, NULL);
1583 #endif /* TIOCNOTTY */
1585 /* Reinitialize the log (because of the fork above). */
1586 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1588 /* Initialize the random number generator. */
1591 /* Chdir to the root directory so that the current disk can be
1592 unmounted if desired. */
1595 /* ignore SIGPIPE */
1596 signal(SIGPIPE, SIG_IGN);
1598 /* Get a connection, either from inetd or a listening TCP socket */
1600 server_accept_inetd(&sock_in, &sock_out);
1602 if ((options.protocol & SSH_PROTO_1) &&
1603 sensitive_data.server_key == NULL)
1604 generate_ephemeral_server_key();
1608 if (options.protocol & SSH_PROTO_1)
1609 generate_ephemeral_server_key();
1611 signal(SIGHUP, sighup_handler);
1612 signal(SIGCHLD, main_sigchld_handler);
1613 signal(SIGTERM, sigterm_handler);
1614 signal(SIGQUIT, sigterm_handler);
1617 * Write out the pid file after the sigterm handler
1618 * is setup and the listen sockets are bound
1621 FILE *f = fopen(options.pid_file, "w");
1624 error("Couldn't create pid file \"%s\": %s",
1625 options.pid_file, strerror(errno));
1627 fprintf(f, "%ld\n", (long) getpid());
1632 /* Accept a connection and return in a forked child */
1633 server_accept_loop(&sock_in, &sock_out,
1634 &newsock, config_s);
1637 /* This is the child processing a new connection. */
1638 setproctitle("%s", "[accepted]");
1641 * Create a new session and process group since the 4.4BSD
1642 * setlogin() affects the entire process group. We don't
1643 * want the child to be able to affect the parent.
1645 #if !defined(SSHD_ACQUIRES_CTTY)
1647 * If setsid is called, on some platforms sshd will later acquire a
1648 * controlling terminal which will result in "could not set
1649 * controlling tty" errors.
1651 if (!debug_flag && !inetd_flag && setsid() < 0)
1652 error("setsid: %.100s", strerror(errno));
1658 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1659 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1660 dup2(newsock, STDIN_FILENO);
1661 dup2(STDIN_FILENO, STDOUT_FILENO);
1662 if (startup_pipe == -1)
1663 close(REEXEC_STARTUP_PIPE_FD);
1665 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1667 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1669 if (startup_pipe != -1)
1670 close(startup_pipe);
1672 execv(rexec_argv[0], rexec_argv);
1674 /* Reexec has failed, fall back and continue */
1675 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1676 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1677 log_init(__progname, options.log_level,
1678 options.log_facility, log_stderr);
1681 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1683 close(REEXEC_CONFIG_PASS_FD);
1684 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1685 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1686 dup2(fd, STDIN_FILENO);
1687 dup2(fd, STDOUT_FILENO);
1688 if (fd > STDERR_FILENO)
1691 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1692 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1696 * Disable the key regeneration alarm. We will not regenerate the
1697 * key since we are no longer in a position to give it to anyone. We
1698 * will not restart on SIGHUP since it no longer makes sense.
1701 signal(SIGALRM, SIG_DFL);
1702 signal(SIGHUP, SIG_DFL);
1703 signal(SIGTERM, SIG_DFL);
1704 signal(SIGQUIT, SIG_DFL);
1705 signal(SIGCHLD, SIG_DFL);
1706 signal(SIGINT, SIG_DFL);
1709 * Register our connection. This turns encryption off because we do
1712 packet_set_connection(sock_in, sock_out);
1713 packet_set_server();
1715 /* Set SO_KEEPALIVE if requested. */
1716 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1717 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1718 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1720 if ((remote_port = get_remote_port()) < 0) {
1721 debug("get_remote_port failed");
1726 * We use get_canonical_hostname with usedns = 0 instead of
1727 * get_remote_ipaddr here so IP options will be checked.
1729 (void) get_canonical_hostname(0);
1731 * The rest of the code depends on the fact that
1732 * get_remote_ipaddr() caches the remote ip, even if
1733 * the socket goes away.
1735 remote_ip = get_remote_ipaddr();
1737 #ifdef SSH_AUDIT_EVENTS
1738 audit_connection_from(remote_ip, remote_port);
1741 /* Check whether logins are denied from this host. */
1742 if (packet_connection_is_on_socket()) {
1743 struct request_info req;
1745 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1748 if (!hosts_access(&req)) {
1749 debug("Connection refused by tcp wrapper");
1752 fatal("libwrap refuse returns");
1755 #endif /* LIBWRAP */
1757 /* Log the connection. */
1758 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1760 #ifdef USE_SECURITY_SESSION_API
1762 * Create a new security session for use by the new user login if
1763 * the current session is the root session or we are not launched
1764 * by inetd (eg: debugging mode or server mode). We do not
1765 * necessarily need to create a session if we are launched from
1766 * inetd because Panther xinetd will create a session for us.
1768 * The only case where this logic will fail is if there is an
1769 * inetd running in a non-root session which is not creating
1770 * new sessions for us. Then all the users will end up in the
1771 * same session (bad).
1773 * When the client exits, the session will be destroyed for us
1776 * We must create the session before any credentials are stored
1777 * (including AFS pags, which happens a few lines below).
1781 SecuritySessionId sid = 0;
1782 SessionAttributeBits sattrs = 0;
1784 err = SessionGetInfo(callerSecuritySession, &sid, &sattrs);
1786 error("SessionGetInfo() failed with error %.8X",
1789 debug("Current Session ID is %.8X / Session Attributes are %.8X",
1790 (unsigned) sid, (unsigned) sattrs);
1792 if (inetd_flag && !(sattrs & sessionIsRoot))
1793 debug("Running in inetd mode in a non-root session... "
1794 "assuming inetd created the session for us.");
1796 debug("Creating new security session...");
1797 err = SessionCreate(0, sessionHasTTY | sessionIsRemote);
1799 error("SessionCreate() failed with error %.8X",
1802 err = SessionGetInfo(callerSecuritySession, &sid,
1805 error("SessionGetInfo() failed with error %.8X",
1808 debug("New Session ID is %.8X / Session Attributes are %.8X",
1809 (unsigned) sid, (unsigned) sattrs);
1815 * We don't want to listen forever unless the other side
1816 * successfully authenticates itself. So we set up an alarm which is
1817 * cleared after successful authentication. A limit of zero
1818 * indicates no limit. Note that we don't set the alarm in debugging
1819 * mode; it is just annoying to have the server exit just when you
1820 * are about to discover the bug.
1822 signal(SIGALRM, grace_alarm_handler);
1824 alarm(options.login_grace_time);
1826 sshd_exchange_identification(sock_in, sock_out);
1828 packet_set_nonblocking();
1830 /* allocate authentication context */
1831 authctxt = xcalloc(1, sizeof(*authctxt));
1833 authctxt->loginmsg = &loginmsg;
1835 /* XXX global for cleanup, access from other modules */
1836 the_authctxt = authctxt;
1838 /* prepare buffer to collect messages to display to user after login */
1839 buffer_init(&loginmsg);
1842 if (privsep_preauth(authctxt) == 1)
1845 /* perform the key exchange */
1846 /* authenticate user and start session */
1849 do_authentication2(authctxt);
1852 do_authentication(authctxt);
1855 * If we use privilege separation, the unprivileged child transfers
1856 * the current keystate and exits
1859 mm_send_keystate(pmonitor);
1865 * Cancel the alarm we set to limit the time taken for
1869 signal(SIGALRM, SIG_DFL);
1870 authctxt->authenticated = 1;
1871 if (startup_pipe != -1) {
1872 close(startup_pipe);
1876 #ifdef SSH_AUDIT_EVENTS
1877 audit_event(SSH_AUTH_SUCCESS);
1881 * In privilege separation, we fork another child and prepare
1882 * file descriptor passing.
1885 privsep_postauth(authctxt);
1886 /* the monitor process [priv] will not return */
1888 destroy_sensitive_data();
1891 /* Start session. */
1892 do_authenticated(authctxt);
1894 /* The connection has been terminated. */
1895 verbose("Closing connection to %.100s", remote_ip);
1898 if (options.use_pam)
1900 #endif /* USE_PAM */
1902 #ifdef SSH_AUDIT_EVENTS
1903 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1915 * Decrypt session_key_int using our private server key and private host key
1916 * (key with larger modulus first).
1919 ssh1_session_key(BIGNUM *session_key_int)
1923 if (BN_cmp(sensitive_data.server_key->rsa->n,
1924 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1925 /* Server key has bigger modulus. */
1926 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1927 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1928 SSH_KEY_BITS_RESERVED) {
1929 fatal("do_connection: %s: "
1930 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1931 get_remote_ipaddr(),
1932 BN_num_bits(sensitive_data.server_key->rsa->n),
1933 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1934 SSH_KEY_BITS_RESERVED);
1936 if (rsa_private_decrypt(session_key_int, session_key_int,
1937 sensitive_data.server_key->rsa) <= 0)
1939 if (rsa_private_decrypt(session_key_int, session_key_int,
1940 sensitive_data.ssh1_host_key->rsa) <= 0)
1943 /* Host key has bigger modulus (or they are equal). */
1944 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1945 BN_num_bits(sensitive_data.server_key->rsa->n) +
1946 SSH_KEY_BITS_RESERVED) {
1947 fatal("do_connection: %s: "
1948 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1949 get_remote_ipaddr(),
1950 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1951 BN_num_bits(sensitive_data.server_key->rsa->n),
1952 SSH_KEY_BITS_RESERVED);
1954 if (rsa_private_decrypt(session_key_int, session_key_int,
1955 sensitive_data.ssh1_host_key->rsa) < 0)
1957 if (rsa_private_decrypt(session_key_int, session_key_int,
1958 sensitive_data.server_key->rsa) < 0)
1971 BIGNUM *session_key_int;
1972 u_char session_key[SSH_SESSION_KEY_LENGTH];
1974 u_int cipher_type, auth_mask, protocol_flags;
1978 * Generate check bytes that the client must send back in the user
1979 * packet in order for it to be accepted; this is used to defy ip
1980 * spoofing attacks. Note that this only works against somebody
1981 * doing IP spoofing from a remote machine; any machine on the local
1982 * network can still see outgoing packets and catch the random
1983 * cookie. This only affects rhosts authentication, and this is one
1984 * of the reasons why it is inherently insecure.
1986 for (i = 0; i < 8; i++) {
1989 cookie[i] = rnd & 0xff;
1994 * Send our public key. We include in the packet 64 bits of random
1995 * data that must be matched in the reply in order to prevent IP
1998 packet_start(SSH_SMSG_PUBLIC_KEY);
1999 for (i = 0; i < 8; i++)
2000 packet_put_char(cookie[i]);
2002 /* Store our public server RSA key. */
2003 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2004 packet_put_bignum(sensitive_data.server_key->rsa->e);
2005 packet_put_bignum(sensitive_data.server_key->rsa->n);
2007 /* Store our public host RSA key. */
2008 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2009 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2010 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2012 /* Put protocol flags. */
2013 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2015 /* Declare which ciphers we support. */
2016 packet_put_int(cipher_mask_ssh1(0));
2018 /* Declare supported authentication types. */
2020 if (options.rhosts_rsa_authentication)
2021 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2022 if (options.rsa_authentication)
2023 auth_mask |= 1 << SSH_AUTH_RSA;
2024 if (options.challenge_response_authentication == 1)
2025 auth_mask |= 1 << SSH_AUTH_TIS;
2026 if (options.password_authentication)
2027 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2028 packet_put_int(auth_mask);
2030 /* Send the packet and wait for it to be sent. */
2032 packet_write_wait();
2034 debug("Sent %d bit server key and %d bit host key.",
2035 BN_num_bits(sensitive_data.server_key->rsa->n),
2036 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2038 /* Read clients reply (cipher type and session key). */
2039 packet_read_expect(SSH_CMSG_SESSION_KEY);
2041 /* Get cipher type and check whether we accept this. */
2042 cipher_type = packet_get_char();
2044 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2045 packet_disconnect("Warning: client selects unsupported cipher.");
2047 /* Get check bytes from the packet. These must match those we
2048 sent earlier with the public key packet. */
2049 for (i = 0; i < 8; i++)
2050 if (cookie[i] != packet_get_char())
2051 packet_disconnect("IP Spoofing check bytes do not match.");
2053 debug("Encryption type: %.200s", cipher_name(cipher_type));
2055 /* Get the encrypted integer. */
2056 if ((session_key_int = BN_new()) == NULL)
2057 fatal("do_ssh1_kex: BN_new failed");
2058 packet_get_bignum(session_key_int);
2060 protocol_flags = packet_get_int();
2061 packet_set_protocol_flags(protocol_flags);
2064 /* Decrypt session_key_int using host/server keys */
2065 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2068 * Extract session key from the decrypted integer. The key is in the
2069 * least significant 256 bits of the integer; the first byte of the
2070 * key is in the highest bits.
2073 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2074 len = BN_num_bytes(session_key_int);
2075 if (len < 0 || (u_int)len > sizeof(session_key)) {
2076 error("do_connection: bad session key len from %s: "
2077 "session_key_int %d > sizeof(session_key) %lu",
2078 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2081 memset(session_key, 0, sizeof(session_key));
2082 BN_bn2bin(session_key_int,
2083 session_key + sizeof(session_key) - len);
2085 derive_ssh1_session_id(
2086 sensitive_data.ssh1_host_key->rsa->n,
2087 sensitive_data.server_key->rsa->n,
2088 cookie, session_id);
2090 * Xor the first 16 bytes of the session key with the
2093 for (i = 0; i < 16; i++)
2094 session_key[i] ^= session_id[i];
2098 int bytes = BN_num_bytes(session_key_int);
2099 u_char *buf = xmalloc(bytes);
2102 logit("do_connection: generating a fake encryption key");
2103 BN_bn2bin(session_key_int, buf);
2105 MD5_Update(&md, buf, bytes);
2106 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2107 MD5_Final(session_key, &md);
2109 MD5_Update(&md, session_key, 16);
2110 MD5_Update(&md, buf, bytes);
2111 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2112 MD5_Final(session_key + 16, &md);
2113 memset(buf, 0, bytes);
2115 for (i = 0; i < 16; i++)
2116 session_id[i] = session_key[i] ^ session_key[i + 16];
2118 /* Destroy the private and public keys. No longer. */
2119 destroy_sensitive_data();
2122 mm_ssh1_session_id(session_id);
2124 /* Destroy the decrypted integer. It is no longer needed. */
2125 BN_clear_free(session_key_int);
2127 /* Set the session key. From this on all communications will be encrypted. */
2128 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2130 /* Destroy our copy of the session key. It is no longer needed. */
2131 memset(session_key, 0, sizeof(session_key));
2133 debug("Received session key; encryption turned on.");
2135 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2136 packet_start(SSH_SMSG_SUCCESS);
2138 packet_write_wait();
2142 * SSH2 key exchange: diffie-hellman-group1-sha1
2149 if (options.ciphers != NULL) {
2150 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2151 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2153 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2154 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2155 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2156 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2158 if (options.macs != NULL) {
2159 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2160 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2162 if (options.compression == COMP_NONE) {
2163 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2164 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2165 } else if (options.compression == COMP_DELAYED) {
2166 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2167 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2170 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2176 char *newstr = NULL;
2177 orig = myproposal[PROPOSAL_KEX_ALGS];
2180 * If we don't have a host key, then there's no point advertising
2181 * the other key exchange algorithms
2184 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
2187 if (options.gss_keyex)
2188 gss = ssh_gssapi_server_mechanisms();
2193 xasprintf(&newstr, "%s,%s", gss, orig);
2200 * If we've got GSSAPI mechanisms, then we've got the 'null' host
2201 * key alg, but we can't tell people about it unless its the only
2202 * host key algorithm we support
2204 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
2205 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
2208 myproposal[PROPOSAL_KEX_ALGS] = newstr;
2210 fatal("No supported key exchange algorithms");
2214 /* start key exchange */
2215 kex = kex_setup(myproposal);
2216 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2217 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2218 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2219 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2221 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
2222 kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
2223 kex->kex[KEX_GSS_GEX_SHA1] = kexgss_server;
2226 kex->client_version_string=client_version_string;
2227 kex->server_version_string=server_version_string;
2228 kex->load_host_key=&get_hostkey_by_type;
2229 kex->host_key_index=&get_hostkey_index;
2233 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2235 session_id2 = kex->session_id;
2236 session_id2_len = kex->session_id_len;
2239 /* send 1st encrypted/maced/compressed message */
2240 packet_start(SSH2_MSG_IGNORE);
2241 packet_put_cstring("markus");
2243 packet_write_wait();
2248 /* server specific fatal cleanup */
2253 do_cleanup(the_authctxt);
2254 #ifdef SSH_AUDIT_EVENTS
2255 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2256 if (!use_privsep || mm_is_monitor())
2257 audit_event(SSH_CONNECTION_ABANDON);