1 /* $OpenBSD: sshd.c,v 1.339 2006/07/22 20:48:23 stevesk 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 #ifdef HAVE_SYS_STAT_H
49 # include <sys/stat.h>
51 #include <sys/ioctl.h>
52 #include <sys/socket.h>
66 #include <openssl/dh.h>
67 #include <openssl/bn.h>
68 #include <openssl/md5.h>
69 #include <openssl/rand.h>
70 #ifdef HAVE_SECUREWARE
71 #include <sys/security.h>
92 #include "myproposal.h"
94 #include "pathnames.h"
100 #include "dispatch.h"
101 #include "channels.h"
103 #include "monitor_mm.h"
105 #include "monitor_wrap.h"
106 #include "monitor_fdpass.h"
112 int allow_severity = LOG_INFO;
113 int deny_severity = LOG_WARNING;
121 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
122 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
123 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
124 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
126 extern char *__progname;
128 /* Server configuration options. */
129 ServerOptions options;
131 /* Name of the server configuration file. */
132 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
135 * Debug mode flag. This can be set on the command line. If debug
136 * mode is enabled, extra debugging output will be sent to the system
137 * log, the daemon will not go to background, and will exit after processing
138 * the first connection.
142 /* Flag indicating that the daemon should only test the configuration and keys. */
145 /* Flag indicating that the daemon is being started from inetd. */
148 /* Flag indicating that sshd should not detach and become a daemon. */
149 int no_daemon_flag = 0;
151 /* debug goes to stderr unless inetd_flag is set */
154 /* Saved arguments to main(). */
159 int rexeced_flag = 0;
165 * The sockets that the server is listening; this is used in the SIGHUP
168 #define MAX_LISTEN_SOCKS 16
169 int listen_socks[MAX_LISTEN_SOCKS];
170 int num_listen_socks = 0;
173 * the client's version string, passed by sshd2 in compat mode. if != NULL,
174 * sshd will skip the version-number exchange
176 char *client_version_string = NULL;
177 char *server_version_string = NULL;
179 /* for rekeying XXX fixme */
183 * Any really sensitive data in the application is contained in this
184 * structure. The idea is that this structure could be locked into memory so
185 * that the pages do not get written into swap. However, there are some
186 * problems. The private key contains BIGNUMs, and we do not (in principle)
187 * have access to the internals of them, and locking just the structure is
188 * not very useful. Currently, memory locking is not implemented.
191 Key *server_key; /* ephemeral server key */
192 Key *ssh1_host_key; /* ssh1 host key */
193 Key **host_keys; /* all private host keys */
196 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
200 * Flag indicating whether the RSA server key needs to be regenerated.
201 * Is set in the SIGALRM handler and cleared when the key is regenerated.
203 static volatile sig_atomic_t key_do_regen = 0;
205 /* This is set to true when a signal is received. */
206 static volatile sig_atomic_t received_sighup = 0;
207 static volatile sig_atomic_t received_sigterm = 0;
209 /* session identifier, used by RSA-auth */
210 u_char session_id[16];
213 u_char *session_id2 = NULL;
214 u_int session_id2_len = 0;
216 /* record remote hostname or ip */
217 u_int utmp_len = MAXHOSTNAMELEN;
219 /* options.max_startup sized array of fd ints */
220 int *startup_pipes = NULL;
221 int startup_pipe; /* in child */
223 /* variables used for privilege separation */
224 int use_privsep = -1;
225 struct monitor *pmonitor = NULL;
227 /* global authentication context */
228 Authctxt *the_authctxt = NULL;
230 /* sshd_config buffer */
233 /* message to be displayed after login */
236 /* Prototypes for various functions defined later in this file. */
237 void destroy_sensitive_data(void);
238 void demote_sensitive_data(void);
240 static void do_ssh1_kex(void);
241 static void do_ssh2_kex(void);
244 * Close all listening sockets
247 close_listen_socks(void)
251 for (i = 0; i < num_listen_socks; i++)
252 close(listen_socks[i]);
253 num_listen_socks = -1;
257 close_startup_pipes(void)
262 for (i = 0; i < options.max_startups; i++)
263 if (startup_pipes[i] != -1)
264 close(startup_pipes[i]);
268 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
269 * the effect is to reread the configuration file (and to regenerate
275 sighup_handler(int sig)
277 int save_errno = errno;
280 signal(SIGHUP, sighup_handler);
285 * Called from the main program after receiving SIGHUP.
286 * Restarts the server.
291 logit("Received SIGHUP; restarting.");
292 close_listen_socks();
293 close_startup_pipes();
294 execv(saved_argv[0], saved_argv);
295 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
301 * Generic signal handler for terminating signals in the master daemon.
305 sigterm_handler(int sig)
307 received_sigterm = sig;
311 * SIGCHLD handler. This is called whenever a child dies. This will then
312 * reap any zombies left by exited children.
316 main_sigchld_handler(int sig)
318 int save_errno = errno;
322 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
323 (pid < 0 && errno == EINTR))
326 signal(SIGCHLD, main_sigchld_handler);
331 * Signal handler for the alarm after the login grace period has expired.
335 grace_alarm_handler(int sig)
337 /* XXX no idea how fix this signal handler */
339 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
340 kill(pmonitor->m_pid, SIGALRM);
342 /* Log error and exit. */
343 fatal("Timeout before authentication for %s", get_remote_ipaddr());
347 * Signal handler for the key regeneration alarm. Note that this
348 * alarm only occurs in the daemon waiting for connections, and it does not
349 * do anything with the private key or random state before forking.
350 * Thus there should be no concurrency control/asynchronous execution
354 generate_ephemeral_server_key(void)
359 verbose("Generating %s%d bit RSA key.",
360 sensitive_data.server_key ? "new " : "", options.server_key_bits);
361 if (sensitive_data.server_key != NULL)
362 key_free(sensitive_data.server_key);
363 sensitive_data.server_key = key_generate(KEY_RSA1,
364 options.server_key_bits);
365 verbose("RSA key generation complete.");
367 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
370 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
378 key_regeneration_alarm(int sig)
380 int save_errno = errno;
382 signal(SIGALRM, SIG_DFL);
388 sshd_exchange_identification(int sock_in, int sock_out)
392 int remote_major, remote_minor;
395 char buf[256]; /* Must not be larger than remote_version. */
396 char remote_version[256]; /* Must be at least as big as buf. */
398 if ((options.protocol & SSH_PROTO_1) &&
399 (options.protocol & SSH_PROTO_2)) {
400 major = PROTOCOL_MAJOR_1;
402 } else if (options.protocol & SSH_PROTO_2) {
403 major = PROTOCOL_MAJOR_2;
404 minor = PROTOCOL_MINOR_2;
406 major = PROTOCOL_MAJOR_1;
407 minor = PROTOCOL_MINOR_1;
409 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
410 server_version_string = xstrdup(buf);
412 /* Send our protocol version identification. */
413 if (atomicio(vwrite, sock_out, server_version_string,
414 strlen(server_version_string))
415 != strlen(server_version_string)) {
416 logit("Could not write ident string to %s", get_remote_ipaddr());
420 /* Read other sides version identification. */
421 memset(buf, 0, sizeof(buf));
422 for (i = 0; i < sizeof(buf) - 1; i++) {
423 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
424 logit("Did not receive identification string from %s",
425 get_remote_ipaddr());
428 if (buf[i] == '\r') {
430 /* Kludge for F-Secure Macintosh < 1.0.2 */
432 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
436 if (buf[i] == '\n') {
441 buf[sizeof(buf) - 1] = 0;
442 client_version_string = xstrdup(buf);
445 * Check that the versions match. In future this might accept
446 * several versions and set appropriate flags to handle them.
448 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
449 &remote_major, &remote_minor, remote_version) != 3) {
450 s = "Protocol mismatch.\n";
451 (void) atomicio(vwrite, sock_out, s, strlen(s));
454 logit("Bad protocol version identification '%.100s' from %s",
455 client_version_string, get_remote_ipaddr());
458 debug("Client protocol version %d.%d; client software version %.100s",
459 remote_major, remote_minor, remote_version);
461 compat_datafellows(remote_version);
463 if (datafellows & SSH_BUG_PROBE) {
464 logit("probed from %s with %s. Don't panic.",
465 get_remote_ipaddr(), client_version_string);
469 if (datafellows & SSH_BUG_SCANNER) {
470 logit("scanned from %s with %s. Don't panic.",
471 get_remote_ipaddr(), client_version_string);
476 switch (remote_major) {
478 if (remote_minor == 99) {
479 if (options.protocol & SSH_PROTO_2)
485 if (!(options.protocol & SSH_PROTO_1)) {
489 if (remote_minor < 3) {
490 packet_disconnect("Your ssh version is too old and "
491 "is no longer supported. Please install a newer version.");
492 } else if (remote_minor == 3) {
493 /* note that this disables agent-forwarding */
498 if (options.protocol & SSH_PROTO_2) {
507 chop(server_version_string);
508 debug("Local version string %.200s", server_version_string);
511 s = "Protocol major versions differ.\n";
512 (void) atomicio(vwrite, sock_out, s, strlen(s));
515 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
517 server_version_string, client_version_string);
522 /* Destroy the host and server keys. They will no longer be needed. */
524 destroy_sensitive_data(void)
528 if (sensitive_data.server_key) {
529 key_free(sensitive_data.server_key);
530 sensitive_data.server_key = NULL;
532 for (i = 0; i < options.num_host_key_files; i++) {
533 if (sensitive_data.host_keys[i]) {
534 key_free(sensitive_data.host_keys[i]);
535 sensitive_data.host_keys[i] = NULL;
538 sensitive_data.ssh1_host_key = NULL;
539 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
542 /* Demote private to public keys for network child */
544 demote_sensitive_data(void)
549 if (sensitive_data.server_key) {
550 tmp = key_demote(sensitive_data.server_key);
551 key_free(sensitive_data.server_key);
552 sensitive_data.server_key = tmp;
555 for (i = 0; i < options.num_host_key_files; i++) {
556 if (sensitive_data.host_keys[i]) {
557 tmp = key_demote(sensitive_data.host_keys[i]);
558 key_free(sensitive_data.host_keys[i]);
559 sensitive_data.host_keys[i] = tmp;
560 if (tmp->type == KEY_RSA1)
561 sensitive_data.ssh1_host_key = tmp;
565 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
569 privsep_preauth_child(void)
576 /* Enable challenge-response authentication for privilege separation */
577 privsep_challenge_enable();
579 for (i = 0; i < 256; i++)
580 rnd[i] = arc4random();
581 RAND_seed(rnd, sizeof(rnd));
583 /* Demote the private keys to public keys. */
584 demote_sensitive_data();
586 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
587 fatal("Privilege separation user %s does not exist",
589 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
592 /* Change our root directory */
593 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
594 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
596 if (chdir("/") == -1)
597 fatal("chdir(\"/\"): %s", strerror(errno));
599 /* Drop our privileges */
600 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
603 /* XXX not ready, too heavy after chroot */
604 do_setusercontext(pw);
606 gidset[0] = pw->pw_gid;
607 if (setgroups(1, gidset) < 0)
608 fatal("setgroups: %.100s", strerror(errno));
609 permanently_set_uid(pw);
614 privsep_preauth(Authctxt *authctxt)
619 /* Set up unprivileged child process to deal with network data */
620 pmonitor = monitor_init();
621 /* Store a pointer to the kex for later rekeying */
622 pmonitor->m_pkex = &xxx_kex;
626 fatal("fork of unprivileged child failed");
627 } else if (pid != 0) {
628 debug2("Network child is on pid %ld", (long)pid);
630 close(pmonitor->m_recvfd);
631 pmonitor->m_pid = pid;
632 monitor_child_preauth(authctxt, pmonitor);
633 close(pmonitor->m_sendfd);
636 monitor_sync(pmonitor);
638 /* Wait for the child's exit status */
639 while (waitpid(pid, &status, 0) < 0)
646 close(pmonitor->m_sendfd);
648 /* Demote the child */
649 if (getuid() == 0 || geteuid() == 0)
650 privsep_preauth_child();
651 setproctitle("%s", "[net]");
657 privsep_postauth(Authctxt *authctxt)
659 #ifdef DISABLE_FD_PASSING
662 if (authctxt->pw->pw_uid == 0 || options.use_login) {
664 /* File descriptor passing is broken or root login */
669 /* New socket pair */
670 monitor_reinit(pmonitor);
672 pmonitor->m_pid = fork();
673 if (pmonitor->m_pid == -1)
674 fatal("fork of unprivileged child failed");
675 else if (pmonitor->m_pid != 0) {
676 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
677 close(pmonitor->m_recvfd);
678 buffer_clear(&loginmsg);
679 monitor_child_postauth(pmonitor);
685 close(pmonitor->m_sendfd);
687 /* Demote the private keys to public keys. */
688 demote_sensitive_data();
690 /* Drop privileges */
691 do_setusercontext(authctxt->pw);
694 /* It is safe now to apply the key state */
695 monitor_apply_keystate(pmonitor);
698 * Tell the packet layer that authentication was successful, since
699 * this information is not part of the key state.
701 packet_set_authenticated();
705 list_hostkey_types(void)
713 for (i = 0; i < options.num_host_key_files; i++) {
714 Key *key = sensitive_data.host_keys[i];
720 if (buffer_len(&b) > 0)
721 buffer_append(&b, ",", 1);
722 p = key_ssh_name(key);
723 buffer_append(&b, p, strlen(p));
727 buffer_append(&b, "\0", 1);
728 ret = xstrdup(buffer_ptr(&b));
730 debug("list_hostkey_types: %s", ret);
735 get_hostkey_by_type(int type)
739 for (i = 0; i < options.num_host_key_files; i++) {
740 Key *key = sensitive_data.host_keys[i];
741 if (key != NULL && key->type == type)
748 get_hostkey_by_index(int ind)
750 if (ind < 0 || ind >= options.num_host_key_files)
752 return (sensitive_data.host_keys[ind]);
756 get_hostkey_index(Key *key)
760 for (i = 0; i < options.num_host_key_files; i++) {
761 if (key == sensitive_data.host_keys[i])
768 * returns 1 if connection should be dropped, 0 otherwise.
769 * dropping starts at connection #max_startups_begin with a probability
770 * of (max_startups_rate/100). the probability increases linearly until
771 * all connections are dropped for startups > max_startups
774 drop_connection(int startups)
778 if (startups < options.max_startups_begin)
780 if (startups >= options.max_startups)
782 if (options.max_startups_rate == 100)
785 p = 100 - options.max_startups_rate;
786 p *= startups - options.max_startups_begin;
787 p /= options.max_startups - options.max_startups_begin;
788 p += options.max_startups_rate;
789 r = arc4random() % 100;
791 debug("drop_connection: p %d, r %d", p, r);
792 return (r < p) ? 1 : 0;
798 fprintf(stderr, "%s, %s\n",
799 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
801 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
802 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
808 send_rexec_state(int fd, Buffer *conf)
812 debug3("%s: entering fd = %d config len %d", __func__, fd,
816 * Protocol from reexec master to child:
817 * string configuration
818 * u_int ephemeral_key_follows
819 * bignum e (only if ephemeral_key_follows == 1)
825 * string rngseed (only if OpenSSL is not self-seeded)
828 buffer_put_cstring(&m, buffer_ptr(conf));
830 if (sensitive_data.server_key != NULL &&
831 sensitive_data.server_key->type == KEY_RSA1) {
832 buffer_put_int(&m, 1);
833 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
834 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
835 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
836 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
837 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
838 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
840 buffer_put_int(&m, 0);
842 #ifndef OPENSSL_PRNG_ONLY
843 rexec_send_rng_seed(&m);
846 if (ssh_msg_send(fd, 0, &m) == -1)
847 fatal("%s: ssh_msg_send failed", __func__);
851 debug3("%s: done", __func__);
855 recv_rexec_state(int fd, Buffer *conf)
861 debug3("%s: entering fd = %d", __func__, fd);
865 if (ssh_msg_recv(fd, &m) == -1)
866 fatal("%s: ssh_msg_recv failed", __func__);
867 if (buffer_get_char(&m) != 0)
868 fatal("%s: rexec version mismatch", __func__);
870 cp = buffer_get_string(&m, &len);
872 buffer_append(conf, cp, len + 1);
875 if (buffer_get_int(&m)) {
876 if (sensitive_data.server_key != NULL)
877 key_free(sensitive_data.server_key);
878 sensitive_data.server_key = key_new_private(KEY_RSA1);
879 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
880 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
881 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
882 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
883 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
884 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
885 rsa_generate_additional_parameters(
886 sensitive_data.server_key->rsa);
889 #ifndef OPENSSL_PRNG_ONLY
890 rexec_recv_rng_seed(&m);
895 debug3("%s: done", __func__);
899 * Main program for the daemon.
902 main(int ac, char **av)
906 int opt, j, i, on = 1;
907 int sock_in = -1, sock_out = -1, newsock = -1;
911 struct sockaddr_storage from;
912 const char *remote_ip;
916 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
918 int listen_sock, maxfd;
919 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
923 int ret, key_used = 0;
925 #ifdef HAVE_SECUREWARE
926 (void)set_auth_parameters(ac, av);
928 __progname = ssh_get_progname(av[0]);
931 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
934 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
935 for (i = 0; i < ac; i++)
936 saved_argv[i] = xstrdup(av[i]);
937 saved_argv[i] = NULL;
939 #ifndef HAVE_SETPROCTITLE
940 /* Prepare for later setproctitle emulation */
941 compat_init_setproctitle(ac, av);
945 if (geteuid() == 0 && setgroups(0, NULL) == -1)
946 debug("setgroups(): %.200s", strerror(errno));
948 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
951 /* Initialize configuration options to their default values. */
952 initialize_server_options(&options);
954 /* Parse command-line arguments. */
955 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
958 options.address_family = AF_INET;
961 options.address_family = AF_INET6;
964 config_file_name = optarg;
967 if (debug_flag == 0) {
969 options.log_level = SYSLOG_LEVEL_DEBUG1;
970 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
993 options.log_level = SYSLOG_LEVEL_QUIET;
996 options.server_key_bits = (int)strtonum(optarg, 256,
1000 options.ports_from_cmdline = 1;
1001 if (options.num_ports >= MAX_PORTS) {
1002 fprintf(stderr, "too many ports.\n");
1005 options.ports[options.num_ports++] = a2port(optarg);
1006 if (options.ports[options.num_ports-1] == 0) {
1007 fprintf(stderr, "Bad port number.\n");
1012 if ((options.login_grace_time = convtime(optarg)) == -1) {
1013 fprintf(stderr, "Invalid login grace time.\n");
1018 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1019 fprintf(stderr, "Invalid key regeneration interval.\n");
1024 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1025 fprintf(stderr, "too many host keys.\n");
1028 options.host_key_files[options.num_host_key_files++] = optarg;
1034 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1035 if (utmp_len > MAXHOSTNAMELEN) {
1036 fprintf(stderr, "Invalid utmp length.\n");
1041 line = xstrdup(optarg);
1042 if (process_server_config_line(&options, line,
1043 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1053 if (rexeced_flag || inetd_flag)
1055 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1056 fatal("sshd re-exec requires execution with an absolute path");
1058 closefrom(REEXEC_MIN_FREE_FD);
1060 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1062 SSLeay_add_all_algorithms();
1065 * Force logging to stderr until we have loaded the private host
1066 * key (unless started from inetd)
1068 log_init(__progname,
1069 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1070 SYSLOG_LEVEL_INFO : options.log_level,
1071 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1072 SYSLOG_FACILITY_AUTH : options.log_facility,
1073 log_stderr || !inetd_flag);
1076 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1077 * root's environment
1079 if (getenv("KRB5CCNAME") != NULL)
1080 unsetenv("KRB5CCNAME");
1083 /* Cray can define user privs drop all privs now!
1084 * Not needed on PRIV_SU systems!
1089 sensitive_data.server_key = NULL;
1090 sensitive_data.ssh1_host_key = NULL;
1091 sensitive_data.have_ssh1_key = 0;
1092 sensitive_data.have_ssh2_key = 0;
1094 /* Fetch our configuration */
1097 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1099 load_server_config(config_file_name, &cfg);
1101 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1102 &cfg, NULL, NULL, NULL);
1106 /* Fill in default values for those options not explicitly set. */
1107 fill_default_server_options(&options);
1109 /* set default channel AF */
1110 channel_set_af(options.address_family);
1112 /* Check that there are no remaining arguments. */
1114 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1118 debug("sshd version %.100s", SSH_RELEASE);
1120 /* load private host keys */
1121 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1123 for (i = 0; i < options.num_host_key_files; i++)
1124 sensitive_data.host_keys[i] = NULL;
1126 for (i = 0; i < options.num_host_key_files; i++) {
1127 key = key_load_private(options.host_key_files[i], "", NULL);
1128 sensitive_data.host_keys[i] = key;
1130 error("Could not load host key: %s",
1131 options.host_key_files[i]);
1132 sensitive_data.host_keys[i] = NULL;
1135 switch (key->type) {
1137 sensitive_data.ssh1_host_key = key;
1138 sensitive_data.have_ssh1_key = 1;
1142 sensitive_data.have_ssh2_key = 1;
1145 debug("private host key: #%d type %d %s", i, key->type,
1148 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1149 logit("Disabling protocol version 1. Could not load host key");
1150 options.protocol &= ~SSH_PROTO_1;
1152 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1153 logit("Disabling protocol version 2. Could not load host key");
1154 options.protocol &= ~SSH_PROTO_2;
1156 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1157 logit("sshd: no hostkeys available -- exiting.");
1161 /* Check certain values for sanity. */
1162 if (options.protocol & SSH_PROTO_1) {
1163 if (options.server_key_bits < 512 ||
1164 options.server_key_bits > 32768) {
1165 fprintf(stderr, "Bad server key size.\n");
1169 * Check that server and host key lengths differ sufficiently. This
1170 * is necessary to make double encryption work with rsaref. Oh, I
1171 * hate software patents. I dont know if this can go? Niels
1173 if (options.server_key_bits >
1174 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1175 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1176 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1177 SSH_KEY_BITS_RESERVED) {
1178 options.server_key_bits =
1179 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1180 SSH_KEY_BITS_RESERVED;
1181 debug("Forcing server key to %d bits to make it differ from host key.",
1182 options.server_key_bits);
1189 if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1190 fatal("Privilege separation user %s does not exist",
1192 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1193 (S_ISDIR(st.st_mode) == 0))
1194 fatal("Missing privilege separation directory: %s",
1195 _PATH_PRIVSEP_CHROOT_DIR);
1198 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1199 (st.st_uid != getuid () ||
1200 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1202 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1204 fatal("%s must be owned by root and not group or "
1205 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1208 /* Configuration looks good, so exit if in test mode. */
1213 * Clear out any supplemental groups we may have inherited. This
1214 * prevents inadvertent creation of files with bad modes (in the
1215 * portable version at least, it's certainly possible for PAM
1216 * to create a file, and we can't control the code in every
1217 * module which might be used).
1219 if (setgroups(0, NULL) < 0)
1220 debug("setgroups() failed: %.200s", strerror(errno));
1223 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1224 for (i = 0; i < rexec_argc; i++) {
1225 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1226 rexec_argv[i] = saved_argv[i];
1228 rexec_argv[rexec_argc] = "-R";
1229 rexec_argv[rexec_argc + 1] = NULL;
1232 /* Initialize the log (it is reinitialized below in case we forked). */
1233 if (debug_flag && (!inetd_flag || rexeced_flag))
1235 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1238 * If not in debugging mode, and not started from inetd, disconnect
1239 * from the controlling terminal, and fork. The original process
1242 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1245 #endif /* TIOCNOTTY */
1246 if (daemon(0, 0) < 0)
1247 fatal("daemon() failed: %.200s", strerror(errno));
1249 /* Disconnect from the controlling tty. */
1251 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1253 (void) ioctl(fd, TIOCNOTTY, NULL);
1256 #endif /* TIOCNOTTY */
1258 /* Reinitialize the log (because of the fork above). */
1259 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1261 /* Initialize the random number generator. */
1264 /* Chdir to the root directory so that the current disk can be
1265 unmounted if desired. */
1268 /* ignore SIGPIPE */
1269 signal(SIGPIPE, SIG_IGN);
1271 /* Start listening for a socket, unless started from inetd. */
1277 close(REEXEC_CONFIG_PASS_FD);
1278 sock_in = sock_out = dup(STDIN_FILENO);
1280 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1281 close(REEXEC_STARTUP_PIPE_FD);
1284 sock_in = dup(STDIN_FILENO);
1285 sock_out = dup(STDOUT_FILENO);
1288 * We intentionally do not close the descriptors 0, 1, and 2
1289 * as our code for setting the descriptors won't work if
1290 * ttyfd happens to be one of those.
1292 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1293 dup2(fd, STDIN_FILENO);
1294 dup2(fd, STDOUT_FILENO);
1295 if (fd > STDOUT_FILENO)
1298 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1299 if ((options.protocol & SSH_PROTO_1) &&
1300 sensitive_data.server_key == NULL)
1301 generate_ephemeral_server_key();
1303 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1304 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1306 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1307 fatal("Too many listen sockets. "
1308 "Enlarge MAX_LISTEN_SOCKS");
1309 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1310 ntop, sizeof(ntop), strport, sizeof(strport),
1311 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1312 error("getnameinfo failed: %.100s",
1313 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1317 /* Create socket for listening. */
1318 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1320 if (listen_sock < 0) {
1321 /* kernel may not support ipv6 */
1322 verbose("socket: %.100s", strerror(errno));
1325 if (set_nonblock(listen_sock) == -1) {
1330 * Set socket options.
1331 * Allow local port reuse in TIME_WAIT.
1333 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1334 &on, sizeof(on)) == -1)
1335 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1337 debug("Bind to port %s on %s.", strport, ntop);
1339 /* Bind the socket to the desired port. */
1340 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1342 error("Bind to port %s on %s failed: %.200s.",
1343 strport, ntop, strerror(errno));
1347 listen_socks[num_listen_socks] = listen_sock;
1350 /* Start listening on the port. */
1351 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1352 fatal("listen on [%s]:%s: %.100s",
1353 ntop, strport, strerror(errno));
1354 logit("Server listening on %s port %s.", ntop, strport);
1356 freeaddrinfo(options.listen_addrs);
1358 if (!num_listen_socks)
1359 fatal("Cannot bind any address.");
1361 if (options.protocol & SSH_PROTO_1)
1362 generate_ephemeral_server_key();
1365 * Arrange to restart on SIGHUP. The handler needs
1368 signal(SIGHUP, sighup_handler);
1370 signal(SIGTERM, sigterm_handler);
1371 signal(SIGQUIT, sigterm_handler);
1373 /* Arrange SIGCHLD to be caught. */
1374 signal(SIGCHLD, main_sigchld_handler);
1376 /* Write out the pid file after the sigterm handler is setup */
1379 * Record our pid in /var/run/sshd.pid to make it
1380 * easier to kill the correct sshd. We don't want to
1381 * do this before the bind above because the bind will
1382 * fail if there already is a daemon, and this will
1383 * overwrite any old pid in the file.
1385 f = fopen(options.pid_file, "wb");
1387 error("Couldn't create pid file \"%s\": %s",
1388 options.pid_file, strerror(errno));
1390 fprintf(f, "%ld\n", (long) getpid());
1395 /* setup fd set for listen */
1398 for (i = 0; i < num_listen_socks; i++)
1399 if (listen_socks[i] > maxfd)
1400 maxfd = listen_socks[i];
1401 /* pipes connected to unauthenticated childs */
1402 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1403 for (i = 0; i < options.max_startups; i++)
1404 startup_pipes[i] = -1;
1407 * Stay listening for connections until the system crashes or
1408 * the daemon is killed with a signal.
1411 if (received_sighup)
1415 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1418 for (i = 0; i < num_listen_socks; i++)
1419 FD_SET(listen_socks[i], fdset);
1420 for (i = 0; i < options.max_startups; i++)
1421 if (startup_pipes[i] != -1)
1422 FD_SET(startup_pipes[i], fdset);
1424 /* Wait in select until there is a connection. */
1425 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1426 if (ret < 0 && errno != EINTR)
1427 error("select: %.100s", strerror(errno));
1428 if (received_sigterm) {
1429 logit("Received signal %d; terminating.",
1430 (int) received_sigterm);
1431 close_listen_socks();
1432 unlink(options.pid_file);
1435 if (key_used && key_do_regen) {
1436 generate_ephemeral_server_key();
1443 for (i = 0; i < options.max_startups; i++)
1444 if (startup_pipes[i] != -1 &&
1445 FD_ISSET(startup_pipes[i], fdset)) {
1447 * the read end of the pipe is ready
1448 * if the child has closed the pipe
1449 * after successful authentication
1450 * or if the child has died
1452 close(startup_pipes[i]);
1453 startup_pipes[i] = -1;
1456 for (i = 0; i < num_listen_socks; i++) {
1457 if (!FD_ISSET(listen_socks[i], fdset))
1459 fromlen = sizeof(from);
1460 newsock = accept(listen_socks[i],
1461 (struct sockaddr *)&from, &fromlen);
1463 if (errno != EINTR && errno != EWOULDBLOCK)
1464 error("accept: %.100s", strerror(errno));
1467 if (unset_nonblock(newsock) == -1) {
1471 if (drop_connection(startups) == 1) {
1472 debug("drop connection #%d", startups);
1476 if (pipe(startup_p) == -1) {
1481 if (rexec_flag && socketpair(AF_UNIX,
1482 SOCK_STREAM, 0, config_s) == -1) {
1483 error("reexec socketpair: %s",
1486 close(startup_p[0]);
1487 close(startup_p[1]);
1491 for (j = 0; j < options.max_startups; j++)
1492 if (startup_pipes[j] == -1) {
1493 startup_pipes[j] = startup_p[0];
1494 if (maxfd < startup_p[0])
1495 maxfd = startup_p[0];
1501 * Got connection. Fork a child to handle it, unless
1502 * we are in debugging mode.
1506 * In debugging mode. Close the listening
1507 * socket, and start processing the
1508 * connection without forking.
1510 debug("Server will not fork when running in debugging mode.");
1511 close_listen_socks();
1514 close(startup_p[0]);
1515 close(startup_p[1]);
1519 send_rexec_state(config_s[0],
1526 * Normal production daemon. Fork, and have
1527 * the child process the connection. The
1528 * parent continues listening.
1530 if ((pid = fork()) == 0) {
1532 * Child. Close the listening and
1533 * max_startup sockets. Start using
1534 * the accepted socket. Reinitialize
1535 * logging (since our pid has changed).
1536 * We break out of the loop to handle
1539 startup_pipe = startup_p[1];
1540 close_startup_pipes();
1541 close_listen_socks();
1544 log_init(__progname,
1546 options.log_facility,
1554 /* Parent. Stay in the loop. */
1556 error("fork: %.100s", strerror(errno));
1558 debug("Forked child %ld.", (long)pid);
1560 close(startup_p[1]);
1563 send_rexec_state(config_s[0], &cfg);
1569 * Mark that the key has been used (it
1570 * was "given" to the child).
1572 if ((options.protocol & SSH_PROTO_1) &&
1574 /* Schedule server key regeneration alarm. */
1575 signal(SIGALRM, key_regeneration_alarm);
1576 alarm(options.key_regeneration_time);
1583 /* child process check (or debug mode) */
1584 if (num_listen_socks < 0)
1589 /* This is the child processing a new connection. */
1590 setproctitle("%s", "[accepted]");
1593 * Create a new session and process group since the 4.4BSD
1594 * setlogin() affects the entire process group. We don't
1595 * want the child to be able to affect the parent.
1597 #if !defined(SSHD_ACQUIRES_CTTY)
1599 * If setsid is called, on some platforms sshd will later acquire a
1600 * controlling terminal which will result in "could not set
1601 * controlling tty" errors.
1603 if (!debug_flag && !inetd_flag && setsid() < 0)
1604 error("setsid: %.100s", strerror(errno));
1610 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1611 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1612 dup2(newsock, STDIN_FILENO);
1613 dup2(STDIN_FILENO, STDOUT_FILENO);
1614 if (startup_pipe == -1)
1615 close(REEXEC_STARTUP_PIPE_FD);
1617 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1619 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1621 if (startup_pipe != -1)
1622 close(startup_pipe);
1624 execv(rexec_argv[0], rexec_argv);
1626 /* Reexec has failed, fall back and continue */
1627 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1628 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1629 log_init(__progname, options.log_level,
1630 options.log_facility, log_stderr);
1633 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1635 close(REEXEC_CONFIG_PASS_FD);
1636 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1637 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1638 dup2(fd, STDIN_FILENO);
1639 dup2(fd, STDOUT_FILENO);
1640 if (fd > STDERR_FILENO)
1643 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1644 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1648 * Disable the key regeneration alarm. We will not regenerate the
1649 * key since we are no longer in a position to give it to anyone. We
1650 * will not restart on SIGHUP since it no longer makes sense.
1653 signal(SIGALRM, SIG_DFL);
1654 signal(SIGHUP, SIG_DFL);
1655 signal(SIGTERM, SIG_DFL);
1656 signal(SIGQUIT, SIG_DFL);
1657 signal(SIGCHLD, SIG_DFL);
1658 signal(SIGINT, SIG_DFL);
1661 * Register our connection. This turns encryption off because we do
1664 packet_set_connection(sock_in, sock_out);
1665 packet_set_server();
1667 /* Set SO_KEEPALIVE if requested. */
1668 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1669 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1670 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1672 if ((remote_port = get_remote_port()) < 0) {
1673 debug("get_remote_port failed");
1678 * We use get_canonical_hostname with usedns = 0 instead of
1679 * get_remote_ipaddr here so IP options will be checked.
1681 (void) get_canonical_hostname(0);
1683 * The rest of the code depends on the fact that
1684 * get_remote_ipaddr() caches the remote ip, even if
1685 * the socket goes away.
1687 remote_ip = get_remote_ipaddr();
1689 #ifdef SSH_AUDIT_EVENTS
1690 audit_connection_from(remote_ip, remote_port);
1693 /* Check whether logins are denied from this host. */
1694 if (packet_connection_is_on_socket()) {
1695 struct request_info req;
1697 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1700 if (!hosts_access(&req)) {
1701 debug("Connection refused by tcp wrapper");
1704 fatal("libwrap refuse returns");
1707 #endif /* LIBWRAP */
1709 /* Log the connection. */
1710 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1713 * We don't want to listen forever unless the other side
1714 * successfully authenticates itself. So we set up an alarm which is
1715 * cleared after successful authentication. A limit of zero
1716 * indicates no limit. Note that we don't set the alarm in debugging
1717 * mode; it is just annoying to have the server exit just when you
1718 * are about to discover the bug.
1720 signal(SIGALRM, grace_alarm_handler);
1722 alarm(options.login_grace_time);
1724 sshd_exchange_identification(sock_in, sock_out);
1726 packet_set_nonblocking();
1728 /* allocate authentication context */
1729 authctxt = xcalloc(1, sizeof(*authctxt));
1731 authctxt->loginmsg = &loginmsg;
1733 /* XXX global for cleanup, access from other modules */
1734 the_authctxt = authctxt;
1736 /* prepare buffer to collect messages to display to user after login */
1737 buffer_init(&loginmsg);
1740 if (privsep_preauth(authctxt) == 1)
1743 /* perform the key exchange */
1744 /* authenticate user and start session */
1747 do_authentication2(authctxt);
1750 do_authentication(authctxt);
1753 * If we use privilege separation, the unprivileged child transfers
1754 * the current keystate and exits
1757 mm_send_keystate(pmonitor);
1763 * Cancel the alarm we set to limit the time taken for
1767 signal(SIGALRM, SIG_DFL);
1768 if (startup_pipe != -1) {
1769 close(startup_pipe);
1773 #ifdef SSH_AUDIT_EVENTS
1774 audit_event(SSH_AUTH_SUCCESS);
1778 * In privilege separation, we fork another child and prepare
1779 * file descriptor passing.
1782 privsep_postauth(authctxt);
1783 /* the monitor process [priv] will not return */
1785 destroy_sensitive_data();
1788 /* Start session. */
1789 do_authenticated(authctxt);
1791 /* The connection has been terminated. */
1792 verbose("Closing connection to %.100s", remote_ip);
1795 if (options.use_pam)
1797 #endif /* USE_PAM */
1799 #ifdef SSH_AUDIT_EVENTS
1800 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1812 * Decrypt session_key_int using our private server key and private host key
1813 * (key with larger modulus first).
1816 ssh1_session_key(BIGNUM *session_key_int)
1820 if (BN_cmp(sensitive_data.server_key->rsa->n,
1821 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1822 /* Server key has bigger modulus. */
1823 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1824 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1825 SSH_KEY_BITS_RESERVED) {
1826 fatal("do_connection: %s: "
1827 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1828 get_remote_ipaddr(),
1829 BN_num_bits(sensitive_data.server_key->rsa->n),
1830 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1831 SSH_KEY_BITS_RESERVED);
1833 if (rsa_private_decrypt(session_key_int, session_key_int,
1834 sensitive_data.server_key->rsa) <= 0)
1836 if (rsa_private_decrypt(session_key_int, session_key_int,
1837 sensitive_data.ssh1_host_key->rsa) <= 0)
1840 /* Host key has bigger modulus (or they are equal). */
1841 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1842 BN_num_bits(sensitive_data.server_key->rsa->n) +
1843 SSH_KEY_BITS_RESERVED) {
1844 fatal("do_connection: %s: "
1845 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1846 get_remote_ipaddr(),
1847 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1848 BN_num_bits(sensitive_data.server_key->rsa->n),
1849 SSH_KEY_BITS_RESERVED);
1851 if (rsa_private_decrypt(session_key_int, session_key_int,
1852 sensitive_data.ssh1_host_key->rsa) < 0)
1854 if (rsa_private_decrypt(session_key_int, session_key_int,
1855 sensitive_data.server_key->rsa) < 0)
1868 BIGNUM *session_key_int;
1869 u_char session_key[SSH_SESSION_KEY_LENGTH];
1871 u_int cipher_type, auth_mask, protocol_flags;
1875 * Generate check bytes that the client must send back in the user
1876 * packet in order for it to be accepted; this is used to defy ip
1877 * spoofing attacks. Note that this only works against somebody
1878 * doing IP spoofing from a remote machine; any machine on the local
1879 * network can still see outgoing packets and catch the random
1880 * cookie. This only affects rhosts authentication, and this is one
1881 * of the reasons why it is inherently insecure.
1883 for (i = 0; i < 8; i++) {
1886 cookie[i] = rnd & 0xff;
1891 * Send our public key. We include in the packet 64 bits of random
1892 * data that must be matched in the reply in order to prevent IP
1895 packet_start(SSH_SMSG_PUBLIC_KEY);
1896 for (i = 0; i < 8; i++)
1897 packet_put_char(cookie[i]);
1899 /* Store our public server RSA key. */
1900 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1901 packet_put_bignum(sensitive_data.server_key->rsa->e);
1902 packet_put_bignum(sensitive_data.server_key->rsa->n);
1904 /* Store our public host RSA key. */
1905 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1906 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1907 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1909 /* Put protocol flags. */
1910 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1912 /* Declare which ciphers we support. */
1913 packet_put_int(cipher_mask_ssh1(0));
1915 /* Declare supported authentication types. */
1917 if (options.rhosts_rsa_authentication)
1918 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1919 if (options.rsa_authentication)
1920 auth_mask |= 1 << SSH_AUTH_RSA;
1921 if (options.challenge_response_authentication == 1)
1922 auth_mask |= 1 << SSH_AUTH_TIS;
1923 if (options.password_authentication)
1924 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1925 packet_put_int(auth_mask);
1927 /* Send the packet and wait for it to be sent. */
1929 packet_write_wait();
1931 debug("Sent %d bit server key and %d bit host key.",
1932 BN_num_bits(sensitive_data.server_key->rsa->n),
1933 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1935 /* Read clients reply (cipher type and session key). */
1936 packet_read_expect(SSH_CMSG_SESSION_KEY);
1938 /* Get cipher type and check whether we accept this. */
1939 cipher_type = packet_get_char();
1941 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1942 packet_disconnect("Warning: client selects unsupported cipher.");
1944 /* Get check bytes from the packet. These must match those we
1945 sent earlier with the public key packet. */
1946 for (i = 0; i < 8; i++)
1947 if (cookie[i] != packet_get_char())
1948 packet_disconnect("IP Spoofing check bytes do not match.");
1950 debug("Encryption type: %.200s", cipher_name(cipher_type));
1952 /* Get the encrypted integer. */
1953 if ((session_key_int = BN_new()) == NULL)
1954 fatal("do_ssh1_kex: BN_new failed");
1955 packet_get_bignum(session_key_int);
1957 protocol_flags = packet_get_int();
1958 packet_set_protocol_flags(protocol_flags);
1961 /* Decrypt session_key_int using host/server keys */
1962 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1965 * Extract session key from the decrypted integer. The key is in the
1966 * least significant 256 bits of the integer; the first byte of the
1967 * key is in the highest bits.
1970 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1971 len = BN_num_bytes(session_key_int);
1972 if (len < 0 || (u_int)len > sizeof(session_key)) {
1973 error("do_connection: bad session key len from %s: "
1974 "session_key_int %d > sizeof(session_key) %lu",
1975 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1978 memset(session_key, 0, sizeof(session_key));
1979 BN_bn2bin(session_key_int,
1980 session_key + sizeof(session_key) - len);
1982 derive_ssh1_session_id(
1983 sensitive_data.ssh1_host_key->rsa->n,
1984 sensitive_data.server_key->rsa->n,
1985 cookie, session_id);
1987 * Xor the first 16 bytes of the session key with the
1990 for (i = 0; i < 16; i++)
1991 session_key[i] ^= session_id[i];
1995 int bytes = BN_num_bytes(session_key_int);
1996 u_char *buf = xmalloc(bytes);
1999 logit("do_connection: generating a fake encryption key");
2000 BN_bn2bin(session_key_int, buf);
2002 MD5_Update(&md, buf, bytes);
2003 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2004 MD5_Final(session_key, &md);
2006 MD5_Update(&md, session_key, 16);
2007 MD5_Update(&md, buf, bytes);
2008 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2009 MD5_Final(session_key + 16, &md);
2010 memset(buf, 0, bytes);
2012 for (i = 0; i < 16; i++)
2013 session_id[i] = session_key[i] ^ session_key[i + 16];
2015 /* Destroy the private and public keys. No longer. */
2016 destroy_sensitive_data();
2019 mm_ssh1_session_id(session_id);
2021 /* Destroy the decrypted integer. It is no longer needed. */
2022 BN_clear_free(session_key_int);
2024 /* Set the session key. From this on all communications will be encrypted. */
2025 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2027 /* Destroy our copy of the session key. It is no longer needed. */
2028 memset(session_key, 0, sizeof(session_key));
2030 debug("Received session key; encryption turned on.");
2032 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2033 packet_start(SSH_SMSG_SUCCESS);
2035 packet_write_wait();
2039 * SSH2 key exchange: diffie-hellman-group1-sha1
2046 if (options.ciphers != NULL) {
2047 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2048 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2050 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2051 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2052 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2053 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2055 if (options.macs != NULL) {
2056 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2057 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2059 if (options.compression == COMP_NONE) {
2060 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2061 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2062 } else if (options.compression == COMP_DELAYED) {
2063 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2064 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2067 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2069 /* start key exchange */
2070 kex = kex_setup(myproposal);
2071 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2072 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2073 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2074 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2076 kex->client_version_string=client_version_string;
2077 kex->server_version_string=server_version_string;
2078 kex->load_host_key=&get_hostkey_by_type;
2079 kex->host_key_index=&get_hostkey_index;
2083 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2085 session_id2 = kex->session_id;
2086 session_id2_len = kex->session_id_len;
2089 /* send 1st encrypted/maced/compressed message */
2090 packet_start(SSH2_MSG_IGNORE);
2091 packet_put_cstring("markus");
2093 packet_write_wait();
2098 /* server specific fatal cleanup */
2103 do_cleanup(the_authctxt);
2104 #ifdef SSH_AUDIT_EVENTS
2105 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2106 if (!use_privsep || mm_is_monitor())
2107 audit_event(SSH_CONNECTION_ABANDON);