2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * This program is the ssh daemon. It listens for connections from clients,
6 * and performs authentication, executes use commands or shell, and forwards
7 * information to/from the application to the user client over an encrypted
8 * connection. This can also handle forwarding of X11, TCP/IP, and
9 * authentication agent connections.
11 * As far as I am concerned, the code I have written for this software
12 * can be used freely for any purpose. Any derived versions of this
13 * software must be clearly marked as such, and if the derived work is
14 * incompatible with the protocol description in the RFC file, it must be
15 * called by a name other than "ssh" or "Secure Shell".
17 * SSH2 implementation:
18 * Privilege Separation:
20 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
21 * Copyright (c) 2002 Niels Provos. All rights reserved.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the above copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
32 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
33 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
34 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
35 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
36 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
37 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
38 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
39 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
40 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
41 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
45 RCSID("$OpenBSD: sshd.c,v 1.319 2006/02/08 12:15:27 stevesk Exp $");
49 #include <openssl/dh.h>
50 #include <openssl/bn.h>
51 #include <openssl/md5.h>
52 #include <openssl/rand.h>
53 #ifdef HAVE_SECUREWARE
54 #include <sys/security.h>
75 #include "myproposal.h"
77 #include "pathnames.h"
86 #include "monitor_mm.h"
88 #include "monitor_wrap.h"
89 #include "monitor_fdpass.h"
94 int allow_severity = LOG_INFO;
95 int deny_severity = LOG_WARNING;
103 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
104 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
105 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
106 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
108 extern char *__progname;
110 /* Server configuration options. */
111 ServerOptions options;
113 /* Name of the server configuration file. */
114 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
117 * Debug mode flag. This can be set on the command line. If debug
118 * mode is enabled, extra debugging output will be sent to the system
119 * log, the daemon will not go to background, and will exit after processing
120 * the first connection.
124 /* Flag indicating that the daemon should only test the configuration and keys. */
127 /* Flag indicating that the daemon is being started from inetd. */
130 /* Flag indicating that sshd should not detach and become a daemon. */
131 int no_daemon_flag = 0;
133 /* debug goes to stderr unless inetd_flag is set */
136 /* Saved arguments to main(). */
141 int rexeced_flag = 0;
147 * The sockets that the server is listening; this is used in the SIGHUP
150 #define MAX_LISTEN_SOCKS 16
151 int listen_socks[MAX_LISTEN_SOCKS];
152 int num_listen_socks = 0;
155 * the client's version string, passed by sshd2 in compat mode. if != NULL,
156 * sshd will skip the version-number exchange
158 char *client_version_string = NULL;
159 char *server_version_string = NULL;
161 /* for rekeying XXX fixme */
165 * Any really sensitive data in the application is contained in this
166 * structure. The idea is that this structure could be locked into memory so
167 * that the pages do not get written into swap. However, there are some
168 * problems. The private key contains BIGNUMs, and we do not (in principle)
169 * have access to the internals of them, and locking just the structure is
170 * not very useful. Currently, memory locking is not implemented.
173 Key *server_key; /* ephemeral server key */
174 Key *ssh1_host_key; /* ssh1 host key */
175 Key **host_keys; /* all private host keys */
178 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
182 * Flag indicating whether the RSA server key needs to be regenerated.
183 * Is set in the SIGALRM handler and cleared when the key is regenerated.
185 static volatile sig_atomic_t key_do_regen = 0;
187 /* This is set to true when a signal is received. */
188 static volatile sig_atomic_t received_sighup = 0;
189 static volatile sig_atomic_t received_sigterm = 0;
191 /* session identifier, used by RSA-auth */
192 u_char session_id[16];
195 u_char *session_id2 = NULL;
196 u_int session_id2_len = 0;
198 /* record remote hostname or ip */
199 u_int utmp_len = MAXHOSTNAMELEN;
201 /* options.max_startup sized array of fd ints */
202 int *startup_pipes = NULL;
203 int startup_pipe; /* in child */
205 /* variables used for privilege separation */
207 struct monitor *pmonitor = NULL;
209 /* global authentication context */
210 Authctxt *the_authctxt = NULL;
212 /* message to be displayed after login */
215 /* Prototypes for various functions defined later in this file. */
216 void destroy_sensitive_data(void);
217 void demote_sensitive_data(void);
219 static void do_ssh1_kex(void);
220 static void do_ssh2_kex(void);
223 * Close all listening sockets
226 close_listen_socks(void)
230 for (i = 0; i < num_listen_socks; i++)
231 close(listen_socks[i]);
232 num_listen_socks = -1;
236 close_startup_pipes(void)
241 for (i = 0; i < options.max_startups; i++)
242 if (startup_pipes[i] != -1)
243 close(startup_pipes[i]);
247 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
248 * the effect is to reread the configuration file (and to regenerate
252 sighup_handler(int sig)
254 int save_errno = errno;
257 signal(SIGHUP, sighup_handler);
262 * Called from the main program after receiving SIGHUP.
263 * Restarts the server.
268 logit("Received SIGHUP; restarting.");
269 close_listen_socks();
270 close_startup_pipes();
271 execv(saved_argv[0], saved_argv);
272 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
278 * Generic signal handler for terminating signals in the master daemon.
281 sigterm_handler(int sig)
283 received_sigterm = sig;
287 * SIGCHLD handler. This is called whenever a child dies. This will then
288 * reap any zombies left by exited children.
291 main_sigchld_handler(int sig)
293 int save_errno = errno;
297 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
298 (pid < 0 && errno == EINTR))
301 signal(SIGCHLD, main_sigchld_handler);
306 * Signal handler for the alarm after the login grace period has expired.
309 grace_alarm_handler(int sig)
311 /* XXX no idea how fix this signal handler */
313 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
314 kill(pmonitor->m_pid, SIGALRM);
316 /* Log error and exit. */
317 fatal("Timeout before authentication for %s", get_remote_ipaddr());
321 * Signal handler for the key regeneration alarm. Note that this
322 * alarm only occurs in the daemon waiting for connections, and it does not
323 * do anything with the private key or random state before forking.
324 * Thus there should be no concurrency control/asynchronous execution
328 generate_ephemeral_server_key(void)
333 verbose("Generating %s%d bit RSA key.",
334 sensitive_data.server_key ? "new " : "", options.server_key_bits);
335 if (sensitive_data.server_key != NULL)
336 key_free(sensitive_data.server_key);
337 sensitive_data.server_key = key_generate(KEY_RSA1,
338 options.server_key_bits);
339 verbose("RSA key generation complete.");
341 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
344 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
351 key_regeneration_alarm(int sig)
353 int save_errno = errno;
355 signal(SIGALRM, SIG_DFL);
361 sshd_exchange_identification(int sock_in, int sock_out)
365 int remote_major, remote_minor;
368 char buf[256]; /* Must not be larger than remote_version. */
369 char remote_version[256]; /* Must be at least as big as buf. */
371 if ((options.protocol & SSH_PROTO_1) &&
372 (options.protocol & SSH_PROTO_2)) {
373 major = PROTOCOL_MAJOR_1;
375 } else if (options.protocol & SSH_PROTO_2) {
376 major = PROTOCOL_MAJOR_2;
377 minor = PROTOCOL_MINOR_2;
379 major = PROTOCOL_MAJOR_1;
380 minor = PROTOCOL_MINOR_1;
382 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
383 server_version_string = xstrdup(buf);
385 /* Send our protocol version identification. */
386 if (atomicio(vwrite, sock_out, server_version_string,
387 strlen(server_version_string))
388 != strlen(server_version_string)) {
389 logit("Could not write ident string to %s", get_remote_ipaddr());
393 /* Read other sides version identification. */
394 memset(buf, 0, sizeof(buf));
395 for (i = 0; i < sizeof(buf) - 1; i++) {
396 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
397 logit("Did not receive identification string from %s",
398 get_remote_ipaddr());
401 if (buf[i] == '\r') {
403 /* Kludge for F-Secure Macintosh < 1.0.2 */
405 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
409 if (buf[i] == '\n') {
414 buf[sizeof(buf) - 1] = 0;
415 client_version_string = xstrdup(buf);
418 * Check that the versions match. In future this might accept
419 * several versions and set appropriate flags to handle them.
421 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
422 &remote_major, &remote_minor, remote_version) != 3) {
423 s = "Protocol mismatch.\n";
424 (void) atomicio(vwrite, sock_out, s, strlen(s));
427 logit("Bad protocol version identification '%.100s' from %s",
428 client_version_string, get_remote_ipaddr());
431 debug("Client protocol version %d.%d; client software version %.100s",
432 remote_major, remote_minor, remote_version);
434 compat_datafellows(remote_version);
436 if (datafellows & SSH_BUG_PROBE) {
437 logit("probed from %s with %s. Don't panic.",
438 get_remote_ipaddr(), client_version_string);
442 if (datafellows & SSH_BUG_SCANNER) {
443 logit("scanned from %s with %s. Don't panic.",
444 get_remote_ipaddr(), client_version_string);
449 switch (remote_major) {
451 if (remote_minor == 99) {
452 if (options.protocol & SSH_PROTO_2)
458 if (!(options.protocol & SSH_PROTO_1)) {
462 if (remote_minor < 3) {
463 packet_disconnect("Your ssh version is too old and "
464 "is no longer supported. Please install a newer version.");
465 } else if (remote_minor == 3) {
466 /* note that this disables agent-forwarding */
471 if (options.protocol & SSH_PROTO_2) {
480 chop(server_version_string);
481 debug("Local version string %.200s", server_version_string);
484 s = "Protocol major versions differ.\n";
485 (void) atomicio(vwrite, sock_out, s, strlen(s));
488 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
490 server_version_string, client_version_string);
495 /* Destroy the host and server keys. They will no longer be needed. */
497 destroy_sensitive_data(void)
501 if (sensitive_data.server_key) {
502 key_free(sensitive_data.server_key);
503 sensitive_data.server_key = NULL;
505 for (i = 0; i < options.num_host_key_files; i++) {
506 if (sensitive_data.host_keys[i]) {
507 key_free(sensitive_data.host_keys[i]);
508 sensitive_data.host_keys[i] = NULL;
511 sensitive_data.ssh1_host_key = NULL;
512 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
515 /* Demote private to public keys for network child */
517 demote_sensitive_data(void)
522 if (sensitive_data.server_key) {
523 tmp = key_demote(sensitive_data.server_key);
524 key_free(sensitive_data.server_key);
525 sensitive_data.server_key = tmp;
528 for (i = 0; i < options.num_host_key_files; i++) {
529 if (sensitive_data.host_keys[i]) {
530 tmp = key_demote(sensitive_data.host_keys[i]);
531 key_free(sensitive_data.host_keys[i]);
532 sensitive_data.host_keys[i] = tmp;
533 if (tmp->type == KEY_RSA1)
534 sensitive_data.ssh1_host_key = tmp;
538 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
542 privsep_preauth_child(void)
549 /* Enable challenge-response authentication for privilege separation */
550 privsep_challenge_enable();
552 for (i = 0; i < 256; i++)
553 rnd[i] = arc4random();
554 RAND_seed(rnd, sizeof(rnd));
556 /* Demote the private keys to public keys. */
557 demote_sensitive_data();
559 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
560 fatal("Privilege separation user %s does not exist",
562 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
565 /* Change our root directory */
566 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
567 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
569 if (chdir("/") == -1)
570 fatal("chdir(\"/\"): %s", strerror(errno));
572 /* Drop our privileges */
573 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
576 /* XXX not ready, too heavy after chroot */
577 do_setusercontext(pw);
579 gidset[0] = pw->pw_gid;
580 if (setgroups(1, gidset) < 0)
581 fatal("setgroups: %.100s", strerror(errno));
582 permanently_set_uid(pw);
587 privsep_preauth(Authctxt *authctxt)
592 /* Set up unprivileged child process to deal with network data */
593 pmonitor = monitor_init();
594 /* Store a pointer to the kex for later rekeying */
595 pmonitor->m_pkex = &xxx_kex;
599 fatal("fork of unprivileged child failed");
600 } else if (pid != 0) {
601 debug2("Network child is on pid %ld", (long)pid);
603 close(pmonitor->m_recvfd);
604 pmonitor->m_pid = pid;
605 monitor_child_preauth(authctxt, pmonitor);
606 close(pmonitor->m_sendfd);
609 monitor_sync(pmonitor);
611 /* Wait for the child's exit status */
612 while (waitpid(pid, &status, 0) < 0)
619 close(pmonitor->m_sendfd);
621 /* Demote the child */
622 if (getuid() == 0 || geteuid() == 0)
623 privsep_preauth_child();
624 setproctitle("%s", "[net]");
630 privsep_postauth(Authctxt *authctxt)
632 #ifdef DISABLE_FD_PASSING
635 if (authctxt->pw->pw_uid == 0 || options.use_login) {
637 /* File descriptor passing is broken or root login */
642 /* New socket pair */
643 monitor_reinit(pmonitor);
645 pmonitor->m_pid = fork();
646 if (pmonitor->m_pid == -1)
647 fatal("fork of unprivileged child failed");
648 else if (pmonitor->m_pid != 0) {
649 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
650 close(pmonitor->m_recvfd);
651 buffer_clear(&loginmsg);
652 monitor_child_postauth(pmonitor);
658 close(pmonitor->m_sendfd);
660 /* Demote the private keys to public keys. */
661 demote_sensitive_data();
663 /* Drop privileges */
664 do_setusercontext(authctxt->pw);
667 /* It is safe now to apply the key state */
668 monitor_apply_keystate(pmonitor);
671 * Tell the packet layer that authentication was successful, since
672 * this information is not part of the key state.
674 packet_set_authenticated();
678 list_hostkey_types(void)
686 for (i = 0; i < options.num_host_key_files; i++) {
687 Key *key = sensitive_data.host_keys[i];
693 if (buffer_len(&b) > 0)
694 buffer_append(&b, ",", 1);
695 p = key_ssh_name(key);
696 buffer_append(&b, p, strlen(p));
700 buffer_append(&b, "\0", 1);
701 ret = xstrdup(buffer_ptr(&b));
703 debug("list_hostkey_types: %s", ret);
708 get_hostkey_by_type(int type)
712 for (i = 0; i < options.num_host_key_files; i++) {
713 Key *key = sensitive_data.host_keys[i];
714 if (key != NULL && key->type == type)
721 get_hostkey_by_index(int ind)
723 if (ind < 0 || ind >= options.num_host_key_files)
725 return (sensitive_data.host_keys[ind]);
729 get_hostkey_index(Key *key)
733 for (i = 0; i < options.num_host_key_files; i++) {
734 if (key == sensitive_data.host_keys[i])
741 * returns 1 if connection should be dropped, 0 otherwise.
742 * dropping starts at connection #max_startups_begin with a probability
743 * of (max_startups_rate/100). the probability increases linearly until
744 * all connections are dropped for startups > max_startups
747 drop_connection(int startups)
751 if (startups < options.max_startups_begin)
753 if (startups >= options.max_startups)
755 if (options.max_startups_rate == 100)
758 p = 100 - options.max_startups_rate;
759 p *= startups - options.max_startups_begin;
760 p /= options.max_startups - options.max_startups_begin;
761 p += options.max_startups_rate;
762 r = arc4random() % 100;
764 debug("drop_connection: p %d, r %d", p, r);
765 return (r < p) ? 1 : 0;
771 fprintf(stderr, "%s, %s\n",
772 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
774 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
775 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
781 send_rexec_state(int fd, Buffer *conf)
785 debug3("%s: entering fd = %d config len %d", __func__, fd,
789 * Protocol from reexec master to child:
790 * string configuration
791 * u_int ephemeral_key_follows
792 * bignum e (only if ephemeral_key_follows == 1)
798 * string rngseed (only if OpenSSL is not self-seeded)
801 buffer_put_cstring(&m, buffer_ptr(conf));
803 if (sensitive_data.server_key != NULL &&
804 sensitive_data.server_key->type == KEY_RSA1) {
805 buffer_put_int(&m, 1);
806 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
807 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
808 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
809 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
810 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
811 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
813 buffer_put_int(&m, 0);
815 #ifndef OPENSSL_PRNG_ONLY
816 rexec_send_rng_seed(&m);
819 if (ssh_msg_send(fd, 0, &m) == -1)
820 fatal("%s: ssh_msg_send failed", __func__);
824 debug3("%s: done", __func__);
828 recv_rexec_state(int fd, Buffer *conf)
834 debug3("%s: entering fd = %d", __func__, fd);
838 if (ssh_msg_recv(fd, &m) == -1)
839 fatal("%s: ssh_msg_recv failed", __func__);
840 if (buffer_get_char(&m) != 0)
841 fatal("%s: rexec version mismatch", __func__);
843 cp = buffer_get_string(&m, &len);
845 buffer_append(conf, cp, len + 1);
848 if (buffer_get_int(&m)) {
849 if (sensitive_data.server_key != NULL)
850 key_free(sensitive_data.server_key);
851 sensitive_data.server_key = key_new_private(KEY_RSA1);
852 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
853 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
854 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
855 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
856 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
857 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
858 rsa_generate_additional_parameters(
859 sensitive_data.server_key->rsa);
862 #ifndef OPENSSL_PRNG_ONLY
863 rexec_recv_rng_seed(&m);
868 debug3("%s: done", __func__);
872 * Main program for the daemon.
875 main(int ac, char **av)
879 int opt, j, i, fdsetsz, on = 1;
880 int sock_in = -1, sock_out = -1, newsock = -1;
884 struct sockaddr_storage from;
885 const char *remote_ip;
889 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
891 int listen_sock, maxfd;
892 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
896 int ret, key_used = 0;
899 #ifdef HAVE_SECUREWARE
900 (void)set_auth_parameters(ac, av);
902 __progname = ssh_get_progname(av[0]);
905 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
908 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
909 for (i = 0; i < ac; i++)
910 saved_argv[i] = xstrdup(av[i]);
911 saved_argv[i] = NULL;
913 #ifndef HAVE_SETPROCTITLE
914 /* Prepare for later setproctitle emulation */
915 compat_init_setproctitle(ac, av);
919 if (geteuid() == 0 && setgroups(0, NULL) == -1)
920 debug("setgroups(): %.200s", strerror(errno));
922 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
925 /* Initialize configuration options to their default values. */
926 initialize_server_options(&options);
928 /* Parse command-line arguments. */
929 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
932 options.address_family = AF_INET;
935 options.address_family = AF_INET6;
938 config_file_name = optarg;
941 if (debug_flag == 0) {
943 options.log_level = SYSLOG_LEVEL_DEBUG1;
944 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
967 options.log_level = SYSLOG_LEVEL_QUIET;
970 options.server_key_bits = atoi(optarg);
973 options.ports_from_cmdline = 1;
974 if (options.num_ports >= MAX_PORTS) {
975 fprintf(stderr, "too many ports.\n");
978 options.ports[options.num_ports++] = a2port(optarg);
979 if (options.ports[options.num_ports-1] == 0) {
980 fprintf(stderr, "Bad port number.\n");
985 if ((options.login_grace_time = convtime(optarg)) == -1) {
986 fprintf(stderr, "Invalid login grace time.\n");
991 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
992 fprintf(stderr, "Invalid key regeneration interval.\n");
997 if (options.num_host_key_files >= MAX_HOSTKEYS) {
998 fprintf(stderr, "too many host keys.\n");
1001 options.host_key_files[options.num_host_key_files++] = optarg;
1007 utmp_len = atoi(optarg);
1008 if (utmp_len > MAXHOSTNAMELEN) {
1009 fprintf(stderr, "Invalid utmp length.\n");
1014 line = xstrdup(optarg);
1015 if (process_server_config_line(&options, line,
1016 "command-line", 0) != 0)
1026 if (rexeced_flag || inetd_flag)
1028 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1029 fatal("sshd re-exec requires execution with an absolute path");
1031 closefrom(REEXEC_MIN_FREE_FD);
1033 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1035 SSLeay_add_all_algorithms();
1038 * Force logging to stderr until we have loaded the private host
1039 * key (unless started from inetd)
1041 log_init(__progname,
1042 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1043 SYSLOG_LEVEL_INFO : options.log_level,
1044 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1045 SYSLOG_FACILITY_AUTH : options.log_facility,
1046 log_stderr || !inetd_flag);
1049 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1050 * root's environment
1052 if (getenv("KRB5CCNAME") != NULL)
1053 unsetenv("KRB5CCNAME");
1056 /* Cray can define user privs drop all privs now!
1057 * Not needed on PRIV_SU systems!
1062 sensitive_data.server_key = NULL;
1063 sensitive_data.ssh1_host_key = NULL;
1064 sensitive_data.have_ssh1_key = 0;
1065 sensitive_data.have_ssh2_key = 0;
1067 /* Fetch our configuration */
1070 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1072 load_server_config(config_file_name, &cfg);
1074 parse_server_config(&options,
1075 rexeced_flag ? "rexec" : config_file_name, &cfg);
1082 /* Fill in default values for those options not explicitly set. */
1083 fill_default_server_options(&options);
1085 /* set default channel AF */
1086 channel_set_af(options.address_family);
1088 /* Check that there are no remaining arguments. */
1090 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1094 debug("sshd version %.100s", SSH_RELEASE);
1096 /* load private host keys */
1097 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1099 for (i = 0; i < options.num_host_key_files; i++)
1100 sensitive_data.host_keys[i] = NULL;
1102 for (i = 0; i < options.num_host_key_files; i++) {
1103 key = key_load_private(options.host_key_files[i], "", NULL);
1104 sensitive_data.host_keys[i] = key;
1106 error("Could not load host key: %s",
1107 options.host_key_files[i]);
1108 sensitive_data.host_keys[i] = NULL;
1111 switch (key->type) {
1113 sensitive_data.ssh1_host_key = key;
1114 sensitive_data.have_ssh1_key = 1;
1118 sensitive_data.have_ssh2_key = 1;
1121 debug("private host key: #%d type %d %s", i, key->type,
1124 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1125 logit("Disabling protocol version 1. Could not load host key");
1126 options.protocol &= ~SSH_PROTO_1;
1128 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1129 logit("Disabling protocol version 2. Could not load host key");
1130 options.protocol &= ~SSH_PROTO_2;
1132 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1133 logit("sshd: no hostkeys available -- exiting.");
1137 /* Check certain values for sanity. */
1138 if (options.protocol & SSH_PROTO_1) {
1139 if (options.server_key_bits < 512 ||
1140 options.server_key_bits > 32768) {
1141 fprintf(stderr, "Bad server key size.\n");
1145 * Check that server and host key lengths differ sufficiently. This
1146 * is necessary to make double encryption work with rsaref. Oh, I
1147 * hate software patents. I dont know if this can go? Niels
1149 if (options.server_key_bits >
1150 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1151 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1152 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1153 SSH_KEY_BITS_RESERVED) {
1154 options.server_key_bits =
1155 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1156 SSH_KEY_BITS_RESERVED;
1157 debug("Forcing server key to %d bits to make it differ from host key.",
1158 options.server_key_bits);
1166 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1167 fatal("Privilege separation user %s does not exist",
1169 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1170 (S_ISDIR(st.st_mode) == 0))
1171 fatal("Missing privilege separation directory: %s",
1172 _PATH_PRIVSEP_CHROOT_DIR);
1175 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1176 (st.st_uid != getuid () ||
1177 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1179 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1181 fatal("%s must be owned by root and not group or "
1182 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1185 /* Configuration looks good, so exit if in test mode. */
1190 * Clear out any supplemental groups we may have inherited. This
1191 * prevents inadvertent creation of files with bad modes (in the
1192 * portable version at least, it's certainly possible for PAM
1193 * to create a file, and we can't control the code in every
1194 * module which might be used).
1196 if (setgroups(0, NULL) < 0)
1197 debug("setgroups() failed: %.200s", strerror(errno));
1200 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1201 for (i = 0; i < rexec_argc; i++) {
1202 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1203 rexec_argv[i] = saved_argv[i];
1205 rexec_argv[rexec_argc] = "-R";
1206 rexec_argv[rexec_argc + 1] = NULL;
1209 /* Initialize the log (it is reinitialized below in case we forked). */
1210 if (debug_flag && (!inetd_flag || rexeced_flag))
1212 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1215 * If not in debugging mode, and not started from inetd, disconnect
1216 * from the controlling terminal, and fork. The original process
1219 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1222 #endif /* TIOCNOTTY */
1223 if (daemon(0, 0) < 0)
1224 fatal("daemon() failed: %.200s", strerror(errno));
1226 /* Disconnect from the controlling tty. */
1228 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1230 (void) ioctl(fd, TIOCNOTTY, NULL);
1233 #endif /* TIOCNOTTY */
1235 /* Reinitialize the log (because of the fork above). */
1236 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1238 /* Initialize the random number generator. */
1241 /* Chdir to the root directory so that the current disk can be
1242 unmounted if desired. */
1245 /* ignore SIGPIPE */
1246 signal(SIGPIPE, SIG_IGN);
1248 /* Start listening for a socket, unless started from inetd. */
1254 close(REEXEC_CONFIG_PASS_FD);
1255 sock_in = sock_out = dup(STDIN_FILENO);
1257 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1258 close(REEXEC_STARTUP_PIPE_FD);
1261 sock_in = dup(STDIN_FILENO);
1262 sock_out = dup(STDOUT_FILENO);
1265 * We intentionally do not close the descriptors 0, 1, and 2
1266 * as our code for setting the descriptors won't work if
1267 * ttyfd happens to be one of those.
1269 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1270 dup2(fd, STDIN_FILENO);
1271 dup2(fd, STDOUT_FILENO);
1272 if (fd > STDOUT_FILENO)
1275 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1276 if ((options.protocol & SSH_PROTO_1) &&
1277 sensitive_data.server_key == NULL)
1278 generate_ephemeral_server_key();
1280 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1281 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1283 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1284 fatal("Too many listen sockets. "
1285 "Enlarge MAX_LISTEN_SOCKS");
1286 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1287 ntop, sizeof(ntop), strport, sizeof(strport),
1288 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1289 error("getnameinfo failed: %.100s",
1290 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1294 /* Create socket for listening. */
1295 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1297 if (listen_sock < 0) {
1298 /* kernel may not support ipv6 */
1299 verbose("socket: %.100s", strerror(errno));
1302 if (set_nonblock(listen_sock) == -1) {
1307 * Set socket options.
1308 * Allow local port reuse in TIME_WAIT.
1310 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1311 &on, sizeof(on)) == -1)
1312 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1314 debug("Bind to port %s on %s.", strport, ntop);
1316 /* Bind the socket to the desired port. */
1317 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1319 error("Bind to port %s on %s failed: %.200s.",
1320 strport, ntop, strerror(errno));
1324 listen_socks[num_listen_socks] = listen_sock;
1327 /* Start listening on the port. */
1328 logit("Server listening on %s port %s.", ntop, strport);
1329 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1330 fatal("listen: %.100s", strerror(errno));
1333 freeaddrinfo(options.listen_addrs);
1335 if (!num_listen_socks)
1336 fatal("Cannot bind any address.");
1338 if (options.protocol & SSH_PROTO_1)
1339 generate_ephemeral_server_key();
1342 * Arrange to restart on SIGHUP. The handler needs
1345 signal(SIGHUP, sighup_handler);
1347 signal(SIGTERM, sigterm_handler);
1348 signal(SIGQUIT, sigterm_handler);
1350 /* Arrange SIGCHLD to be caught. */
1351 signal(SIGCHLD, main_sigchld_handler);
1353 /* Write out the pid file after the sigterm handler is setup */
1356 * Record our pid in /var/run/sshd.pid to make it
1357 * easier to kill the correct sshd. We don't want to
1358 * do this before the bind above because the bind will
1359 * fail if there already is a daemon, and this will
1360 * overwrite any old pid in the file.
1362 f = fopen(options.pid_file, "wb");
1364 error("Couldn't create pid file \"%s\": %s",
1365 options.pid_file, strerror(errno));
1367 fprintf(f, "%ld\n", (long) getpid());
1372 /* setup fd set for listen */
1375 for (i = 0; i < num_listen_socks; i++)
1376 if (listen_socks[i] > maxfd)
1377 maxfd = listen_socks[i];
1378 /* pipes connected to unauthenticated childs */
1379 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1380 for (i = 0; i < options.max_startups; i++)
1381 startup_pipes[i] = -1;
1384 * Stay listening for connections until the system crashes or
1385 * the daemon is killed with a signal.
1388 if (received_sighup)
1392 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1393 fdset = (fd_set *)xmalloc(fdsetsz);
1394 memset(fdset, 0, fdsetsz);
1396 for (i = 0; i < num_listen_socks; i++)
1397 FD_SET(listen_socks[i], fdset);
1398 for (i = 0; i < options.max_startups; i++)
1399 if (startup_pipes[i] != -1)
1400 FD_SET(startup_pipes[i], fdset);
1402 /* Wait in select until there is a connection. */
1403 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1404 if (ret < 0 && errno != EINTR)
1405 error("select: %.100s", strerror(errno));
1406 if (received_sigterm) {
1407 logit("Received signal %d; terminating.",
1408 (int) received_sigterm);
1409 close_listen_socks();
1410 unlink(options.pid_file);
1413 if (key_used && key_do_regen) {
1414 generate_ephemeral_server_key();
1421 for (i = 0; i < options.max_startups; i++)
1422 if (startup_pipes[i] != -1 &&
1423 FD_ISSET(startup_pipes[i], fdset)) {
1425 * the read end of the pipe is ready
1426 * if the child has closed the pipe
1427 * after successful authentication
1428 * or if the child has died
1430 close(startup_pipes[i]);
1431 startup_pipes[i] = -1;
1434 for (i = 0; i < num_listen_socks; i++) {
1435 if (!FD_ISSET(listen_socks[i], fdset))
1437 fromlen = sizeof(from);
1438 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1441 if (errno != EINTR && errno != EWOULDBLOCK)
1442 error("accept: %.100s", strerror(errno));
1445 if (unset_nonblock(newsock) == -1) {
1449 if (drop_connection(startups) == 1) {
1450 debug("drop connection #%d", startups);
1454 if (pipe(startup_p) == -1) {
1459 if (rexec_flag && socketpair(AF_UNIX,
1460 SOCK_STREAM, 0, config_s) == -1) {
1461 error("reexec socketpair: %s",
1464 close(startup_p[0]);
1465 close(startup_p[1]);
1469 for (j = 0; j < options.max_startups; j++)
1470 if (startup_pipes[j] == -1) {
1471 startup_pipes[j] = startup_p[0];
1472 if (maxfd < startup_p[0])
1473 maxfd = startup_p[0];
1479 * Got connection. Fork a child to handle it, unless
1480 * we are in debugging mode.
1484 * In debugging mode. Close the listening
1485 * socket, and start processing the
1486 * connection without forking.
1488 debug("Server will not fork when running in debugging mode.");
1489 close_listen_socks();
1492 close(startup_p[0]);
1493 close(startup_p[1]);
1497 send_rexec_state(config_s[0],
1504 * Normal production daemon. Fork, and have
1505 * the child process the connection. The
1506 * parent continues listening.
1508 if ((pid = fork()) == 0) {
1510 * Child. Close the listening and max_startup
1511 * sockets. Start using the accepted socket.
1512 * Reinitialize logging (since our pid has
1513 * changed). We break out of the loop to handle
1516 startup_pipe = startup_p[1];
1517 close_startup_pipes();
1518 close_listen_socks();
1521 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1528 /* Parent. Stay in the loop. */
1530 error("fork: %.100s", strerror(errno));
1532 debug("Forked child %ld.", (long)pid);
1534 close(startup_p[1]);
1537 send_rexec_state(config_s[0], &cfg);
1542 /* Mark that the key has been used (it was "given" to the child). */
1543 if ((options.protocol & SSH_PROTO_1) &&
1545 /* Schedule server key regeneration alarm. */
1546 signal(SIGALRM, key_regeneration_alarm);
1547 alarm(options.key_regeneration_time);
1553 /* Close the new socket (the child is now taking care of it). */
1556 /* child process check (or debug mode) */
1557 if (num_listen_socks < 0)
1562 /* This is the child processing a new connection. */
1563 setproctitle("%s", "[accepted]");
1566 * Create a new session and process group since the 4.4BSD
1567 * setlogin() affects the entire process group. We don't
1568 * want the child to be able to affect the parent.
1570 #if !defined(SSHD_ACQUIRES_CTTY)
1572 * If setsid is called, on some platforms sshd will later acquire a
1573 * controlling terminal which will result in "could not set
1574 * controlling tty" errors.
1576 if (!debug_flag && !inetd_flag && setsid() < 0)
1577 error("setsid: %.100s", strerror(errno));
1583 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1584 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1585 dup2(newsock, STDIN_FILENO);
1586 dup2(STDIN_FILENO, STDOUT_FILENO);
1587 if (startup_pipe == -1)
1588 close(REEXEC_STARTUP_PIPE_FD);
1590 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1592 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1594 if (startup_pipe != -1)
1595 close(startup_pipe);
1597 execv(rexec_argv[0], rexec_argv);
1599 /* Reexec has failed, fall back and continue */
1600 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1601 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1602 log_init(__progname, options.log_level,
1603 options.log_facility, log_stderr);
1606 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1608 close(REEXEC_CONFIG_PASS_FD);
1609 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1610 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1611 dup2(fd, STDIN_FILENO);
1612 dup2(fd, STDOUT_FILENO);
1613 if (fd > STDERR_FILENO)
1616 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1617 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1621 * Disable the key regeneration alarm. We will not regenerate the
1622 * key since we are no longer in a position to give it to anyone. We
1623 * will not restart on SIGHUP since it no longer makes sense.
1626 signal(SIGALRM, SIG_DFL);
1627 signal(SIGHUP, SIG_DFL);
1628 signal(SIGTERM, SIG_DFL);
1629 signal(SIGQUIT, SIG_DFL);
1630 signal(SIGCHLD, SIG_DFL);
1631 signal(SIGINT, SIG_DFL);
1634 * Register our connection. This turns encryption off because we do
1637 packet_set_connection(sock_in, sock_out);
1638 packet_set_server();
1640 /* Set SO_KEEPALIVE if requested. */
1641 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1642 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1643 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1645 if ((remote_port = get_remote_port()) < 0) {
1646 debug("get_remote_port failed");
1651 * We use get_canonical_hostname with usedns = 0 instead of
1652 * get_remote_ipaddr here so IP options will be checked.
1654 remote_ip = get_canonical_hostname(0);
1656 #ifdef SSH_AUDIT_EVENTS
1657 audit_connection_from(remote_ip, remote_port);
1660 /* Check whether logins are denied from this host. */
1661 if (packet_connection_is_on_socket()) {
1662 struct request_info req;
1664 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1667 if (!hosts_access(&req)) {
1668 debug("Connection refused by tcp wrapper");
1671 fatal("libwrap refuse returns");
1674 #endif /* LIBWRAP */
1676 /* Log the connection. */
1677 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1680 * We don't want to listen forever unless the other side
1681 * successfully authenticates itself. So we set up an alarm which is
1682 * cleared after successful authentication. A limit of zero
1683 * indicates no limit. Note that we don't set the alarm in debugging
1684 * mode; it is just annoying to have the server exit just when you
1685 * are about to discover the bug.
1687 signal(SIGALRM, grace_alarm_handler);
1689 alarm(options.login_grace_time);
1691 sshd_exchange_identification(sock_in, sock_out);
1693 packet_set_nonblocking();
1695 /* allocate authentication context */
1696 authctxt = xmalloc(sizeof(*authctxt));
1697 memset(authctxt, 0, sizeof(*authctxt));
1699 authctxt->loginmsg = &loginmsg;
1701 /* XXX global for cleanup, access from other modules */
1702 the_authctxt = authctxt;
1704 /* prepare buffer to collect messages to display to user after login */
1705 buffer_init(&loginmsg);
1708 if (privsep_preauth(authctxt) == 1)
1711 /* perform the key exchange */
1712 /* authenticate user and start session */
1715 do_authentication2(authctxt);
1718 do_authentication(authctxt);
1721 * If we use privilege separation, the unprivileged child transfers
1722 * the current keystate and exits
1725 mm_send_keystate(pmonitor);
1731 * Cancel the alarm we set to limit the time taken for
1735 signal(SIGALRM, SIG_DFL);
1736 if (startup_pipe != -1) {
1737 close(startup_pipe);
1741 #ifdef SSH_AUDIT_EVENTS
1742 audit_event(SSH_AUTH_SUCCESS);
1746 * In privilege separation, we fork another child and prepare
1747 * file descriptor passing.
1750 privsep_postauth(authctxt);
1751 /* the monitor process [priv] will not return */
1753 destroy_sensitive_data();
1756 /* Start session. */
1757 do_authenticated(authctxt);
1759 /* The connection has been terminated. */
1760 verbose("Closing connection to %.100s", remote_ip);
1763 if (options.use_pam)
1765 #endif /* USE_PAM */
1767 #ifdef SSH_AUDIT_EVENTS
1768 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1780 * Decrypt session_key_int using our private server key and private host key
1781 * (key with larger modulus first).
1784 ssh1_session_key(BIGNUM *session_key_int)
1788 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1789 /* Server key has bigger modulus. */
1790 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1791 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1792 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1793 get_remote_ipaddr(),
1794 BN_num_bits(sensitive_data.server_key->rsa->n),
1795 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1796 SSH_KEY_BITS_RESERVED);
1798 if (rsa_private_decrypt(session_key_int, session_key_int,
1799 sensitive_data.server_key->rsa) <= 0)
1801 if (rsa_private_decrypt(session_key_int, session_key_int,
1802 sensitive_data.ssh1_host_key->rsa) <= 0)
1805 /* Host key has bigger modulus (or they are equal). */
1806 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1807 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1808 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1809 get_remote_ipaddr(),
1810 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1811 BN_num_bits(sensitive_data.server_key->rsa->n),
1812 SSH_KEY_BITS_RESERVED);
1814 if (rsa_private_decrypt(session_key_int, session_key_int,
1815 sensitive_data.ssh1_host_key->rsa) < 0)
1817 if (rsa_private_decrypt(session_key_int, session_key_int,
1818 sensitive_data.server_key->rsa) < 0)
1831 BIGNUM *session_key_int;
1832 u_char session_key[SSH_SESSION_KEY_LENGTH];
1834 u_int cipher_type, auth_mask, protocol_flags;
1838 * Generate check bytes that the client must send back in the user
1839 * packet in order for it to be accepted; this is used to defy ip
1840 * spoofing attacks. Note that this only works against somebody
1841 * doing IP spoofing from a remote machine; any machine on the local
1842 * network can still see outgoing packets and catch the random
1843 * cookie. This only affects rhosts authentication, and this is one
1844 * of the reasons why it is inherently insecure.
1846 for (i = 0; i < 8; i++) {
1849 cookie[i] = rnd & 0xff;
1854 * Send our public key. We include in the packet 64 bits of random
1855 * data that must be matched in the reply in order to prevent IP
1858 packet_start(SSH_SMSG_PUBLIC_KEY);
1859 for (i = 0; i < 8; i++)
1860 packet_put_char(cookie[i]);
1862 /* Store our public server RSA key. */
1863 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1864 packet_put_bignum(sensitive_data.server_key->rsa->e);
1865 packet_put_bignum(sensitive_data.server_key->rsa->n);
1867 /* Store our public host RSA key. */
1868 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1869 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1870 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1872 /* Put protocol flags. */
1873 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1875 /* Declare which ciphers we support. */
1876 packet_put_int(cipher_mask_ssh1(0));
1878 /* Declare supported authentication types. */
1880 if (options.rhosts_rsa_authentication)
1881 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1882 if (options.rsa_authentication)
1883 auth_mask |= 1 << SSH_AUTH_RSA;
1884 if (options.challenge_response_authentication == 1)
1885 auth_mask |= 1 << SSH_AUTH_TIS;
1886 if (options.password_authentication)
1887 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1888 packet_put_int(auth_mask);
1890 /* Send the packet and wait for it to be sent. */
1892 packet_write_wait();
1894 debug("Sent %d bit server key and %d bit host key.",
1895 BN_num_bits(sensitive_data.server_key->rsa->n),
1896 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1898 /* Read clients reply (cipher type and session key). */
1899 packet_read_expect(SSH_CMSG_SESSION_KEY);
1901 /* Get cipher type and check whether we accept this. */
1902 cipher_type = packet_get_char();
1904 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1905 packet_disconnect("Warning: client selects unsupported cipher.");
1907 /* Get check bytes from the packet. These must match those we
1908 sent earlier with the public key packet. */
1909 for (i = 0; i < 8; i++)
1910 if (cookie[i] != packet_get_char())
1911 packet_disconnect("IP Spoofing check bytes do not match.");
1913 debug("Encryption type: %.200s", cipher_name(cipher_type));
1915 /* Get the encrypted integer. */
1916 if ((session_key_int = BN_new()) == NULL)
1917 fatal("do_ssh1_kex: BN_new failed");
1918 packet_get_bignum(session_key_int);
1920 protocol_flags = packet_get_int();
1921 packet_set_protocol_flags(protocol_flags);
1924 /* Decrypt session_key_int using host/server keys */
1925 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1928 * Extract session key from the decrypted integer. The key is in the
1929 * least significant 256 bits of the integer; the first byte of the
1930 * key is in the highest bits.
1933 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1934 len = BN_num_bytes(session_key_int);
1935 if (len < 0 || (u_int)len > sizeof(session_key)) {
1936 error("do_connection: bad session key len from %s: "
1937 "session_key_int %d > sizeof(session_key) %lu",
1938 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1941 memset(session_key, 0, sizeof(session_key));
1942 BN_bn2bin(session_key_int,
1943 session_key + sizeof(session_key) - len);
1945 derive_ssh1_session_id(
1946 sensitive_data.ssh1_host_key->rsa->n,
1947 sensitive_data.server_key->rsa->n,
1948 cookie, session_id);
1950 * Xor the first 16 bytes of the session key with the
1953 for (i = 0; i < 16; i++)
1954 session_key[i] ^= session_id[i];
1958 int bytes = BN_num_bytes(session_key_int);
1959 u_char *buf = xmalloc(bytes);
1962 logit("do_connection: generating a fake encryption key");
1963 BN_bn2bin(session_key_int, buf);
1965 MD5_Update(&md, buf, bytes);
1966 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1967 MD5_Final(session_key, &md);
1969 MD5_Update(&md, session_key, 16);
1970 MD5_Update(&md, buf, bytes);
1971 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1972 MD5_Final(session_key + 16, &md);
1973 memset(buf, 0, bytes);
1975 for (i = 0; i < 16; i++)
1976 session_id[i] = session_key[i] ^ session_key[i + 16];
1978 /* Destroy the private and public keys. No longer. */
1979 destroy_sensitive_data();
1982 mm_ssh1_session_id(session_id);
1984 /* Destroy the decrypted integer. It is no longer needed. */
1985 BN_clear_free(session_key_int);
1987 /* Set the session key. From this on all communications will be encrypted. */
1988 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1990 /* Destroy our copy of the session key. It is no longer needed. */
1991 memset(session_key, 0, sizeof(session_key));
1993 debug("Received session key; encryption turned on.");
1995 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1996 packet_start(SSH_SMSG_SUCCESS);
1998 packet_write_wait();
2002 * SSH2 key exchange: diffie-hellman-group1-sha1
2009 if (options.ciphers != NULL) {
2010 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2011 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2013 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2014 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2015 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2016 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2018 if (options.macs != NULL) {
2019 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2020 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2022 if (options.compression == COMP_NONE) {
2023 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2024 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2025 } else if (options.compression == COMP_DELAYED) {
2026 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2027 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2030 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2032 /* start key exchange */
2033 kex = kex_setup(myproposal);
2034 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2035 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2036 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2038 kex->client_version_string=client_version_string;
2039 kex->server_version_string=server_version_string;
2040 kex->load_host_key=&get_hostkey_by_type;
2041 kex->host_key_index=&get_hostkey_index;
2045 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2047 session_id2 = kex->session_id;
2048 session_id2_len = kex->session_id_len;
2051 /* send 1st encrypted/maced/compressed message */
2052 packet_start(SSH2_MSG_IGNORE);
2053 packet_put_cstring("markus");
2055 packet_write_wait();
2060 /* server specific fatal cleanup */
2065 do_cleanup(the_authctxt);
2066 #ifdef SSH_AUDIT_EVENTS
2067 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2068 if (!use_privsep || mm_is_monitor())
2069 audit_event(SSH_CONNECTION_ABANDON);