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 1.320 2006/02/10 00:27:13 stevesk Exp $");
47 #include <sys/ioctl.h>
51 #include <openssl/dh.h>
52 #include <openssl/bn.h>
53 #include <openssl/md5.h>
54 #include <openssl/rand.h>
55 #ifdef HAVE_SECUREWARE
56 #include <sys/security.h>
77 #include "myproposal.h"
79 #include "pathnames.h"
88 #include "monitor_mm.h"
90 #include "monitor_wrap.h"
91 #include "monitor_fdpass.h"
96 int allow_severity = LOG_INFO;
97 int deny_severity = LOG_WARNING;
105 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
106 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
107 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
108 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
110 extern char *__progname;
112 /* Server configuration options. */
113 ServerOptions options;
115 /* Name of the server configuration file. */
116 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
119 * Debug mode flag. This can be set on the command line. If debug
120 * mode is enabled, extra debugging output will be sent to the system
121 * log, the daemon will not go to background, and will exit after processing
122 * the first connection.
126 /* Flag indicating that the daemon should only test the configuration and keys. */
129 /* Flag indicating that the daemon is being started from inetd. */
132 /* Flag indicating that sshd should not detach and become a daemon. */
133 int no_daemon_flag = 0;
135 /* debug goes to stderr unless inetd_flag is set */
138 /* Saved arguments to main(). */
143 int rexeced_flag = 0;
149 * The sockets that the server is listening; this is used in the SIGHUP
152 #define MAX_LISTEN_SOCKS 16
153 int listen_socks[MAX_LISTEN_SOCKS];
154 int num_listen_socks = 0;
157 * the client's version string, passed by sshd2 in compat mode. if != NULL,
158 * sshd will skip the version-number exchange
160 char *client_version_string = NULL;
161 char *server_version_string = NULL;
163 /* for rekeying XXX fixme */
167 * Any really sensitive data in the application is contained in this
168 * structure. The idea is that this structure could be locked into memory so
169 * that the pages do not get written into swap. However, there are some
170 * problems. The private key contains BIGNUMs, and we do not (in principle)
171 * have access to the internals of them, and locking just the structure is
172 * not very useful. Currently, memory locking is not implemented.
175 Key *server_key; /* ephemeral server key */
176 Key *ssh1_host_key; /* ssh1 host key */
177 Key **host_keys; /* all private host keys */
180 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
184 * Flag indicating whether the RSA server key needs to be regenerated.
185 * Is set in the SIGALRM handler and cleared when the key is regenerated.
187 static volatile sig_atomic_t key_do_regen = 0;
189 /* This is set to true when a signal is received. */
190 static volatile sig_atomic_t received_sighup = 0;
191 static volatile sig_atomic_t received_sigterm = 0;
193 /* session identifier, used by RSA-auth */
194 u_char session_id[16];
197 u_char *session_id2 = NULL;
198 u_int session_id2_len = 0;
200 /* record remote hostname or ip */
201 u_int utmp_len = MAXHOSTNAMELEN;
203 /* options.max_startup sized array of fd ints */
204 int *startup_pipes = NULL;
205 int startup_pipe; /* in child */
207 /* variables used for privilege separation */
209 struct monitor *pmonitor = NULL;
211 /* global authentication context */
212 Authctxt *the_authctxt = NULL;
214 /* message to be displayed after login */
217 /* Prototypes for various functions defined later in this file. */
218 void destroy_sensitive_data(void);
219 void demote_sensitive_data(void);
221 static void do_ssh1_kex(void);
222 static void do_ssh2_kex(void);
225 * Close all listening sockets
228 close_listen_socks(void)
232 for (i = 0; i < num_listen_socks; i++)
233 close(listen_socks[i]);
234 num_listen_socks = -1;
238 close_startup_pipes(void)
243 for (i = 0; i < options.max_startups; i++)
244 if (startup_pipes[i] != -1)
245 close(startup_pipes[i]);
249 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
250 * the effect is to reread the configuration file (and to regenerate
254 sighup_handler(int sig)
256 int save_errno = errno;
259 signal(SIGHUP, sighup_handler);
264 * Called from the main program after receiving SIGHUP.
265 * Restarts the server.
270 logit("Received SIGHUP; restarting.");
271 close_listen_socks();
272 close_startup_pipes();
273 execv(saved_argv[0], saved_argv);
274 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
280 * Generic signal handler for terminating signals in the master daemon.
283 sigterm_handler(int sig)
285 received_sigterm = sig;
289 * SIGCHLD handler. This is called whenever a child dies. This will then
290 * reap any zombies left by exited children.
293 main_sigchld_handler(int sig)
295 int save_errno = errno;
299 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
300 (pid < 0 && errno == EINTR))
303 signal(SIGCHLD, main_sigchld_handler);
308 * Signal handler for the alarm after the login grace period has expired.
311 grace_alarm_handler(int sig)
313 /* XXX no idea how fix this signal handler */
315 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
316 kill(pmonitor->m_pid, SIGALRM);
318 /* Log error and exit. */
319 fatal("Timeout before authentication for %s", get_remote_ipaddr());
323 * Signal handler for the key regeneration alarm. Note that this
324 * alarm only occurs in the daemon waiting for connections, and it does not
325 * do anything with the private key or random state before forking.
326 * Thus there should be no concurrency control/asynchronous execution
330 generate_ephemeral_server_key(void)
335 verbose("Generating %s%d bit RSA key.",
336 sensitive_data.server_key ? "new " : "", options.server_key_bits);
337 if (sensitive_data.server_key != NULL)
338 key_free(sensitive_data.server_key);
339 sensitive_data.server_key = key_generate(KEY_RSA1,
340 options.server_key_bits);
341 verbose("RSA key generation complete.");
343 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
346 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
353 key_regeneration_alarm(int sig)
355 int save_errno = errno;
357 signal(SIGALRM, SIG_DFL);
363 sshd_exchange_identification(int sock_in, int sock_out)
367 int remote_major, remote_minor;
370 char buf[256]; /* Must not be larger than remote_version. */
371 char remote_version[256]; /* Must be at least as big as buf. */
373 if ((options.protocol & SSH_PROTO_1) &&
374 (options.protocol & SSH_PROTO_2)) {
375 major = PROTOCOL_MAJOR_1;
377 } else if (options.protocol & SSH_PROTO_2) {
378 major = PROTOCOL_MAJOR_2;
379 minor = PROTOCOL_MINOR_2;
381 major = PROTOCOL_MAJOR_1;
382 minor = PROTOCOL_MINOR_1;
384 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
385 server_version_string = xstrdup(buf);
387 /* Send our protocol version identification. */
388 if (atomicio(vwrite, sock_out, server_version_string,
389 strlen(server_version_string))
390 != strlen(server_version_string)) {
391 logit("Could not write ident string to %s", get_remote_ipaddr());
395 /* Read other sides version identification. */
396 memset(buf, 0, sizeof(buf));
397 for (i = 0; i < sizeof(buf) - 1; i++) {
398 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
399 logit("Did not receive identification string from %s",
400 get_remote_ipaddr());
403 if (buf[i] == '\r') {
405 /* Kludge for F-Secure Macintosh < 1.0.2 */
407 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
411 if (buf[i] == '\n') {
416 buf[sizeof(buf) - 1] = 0;
417 client_version_string = xstrdup(buf);
420 * Check that the versions match. In future this might accept
421 * several versions and set appropriate flags to handle them.
423 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
424 &remote_major, &remote_minor, remote_version) != 3) {
425 s = "Protocol mismatch.\n";
426 (void) atomicio(vwrite, sock_out, s, strlen(s));
429 logit("Bad protocol version identification '%.100s' from %s",
430 client_version_string, get_remote_ipaddr());
433 debug("Client protocol version %d.%d; client software version %.100s",
434 remote_major, remote_minor, remote_version);
436 compat_datafellows(remote_version);
438 if (datafellows & SSH_BUG_PROBE) {
439 logit("probed from %s with %s. Don't panic.",
440 get_remote_ipaddr(), client_version_string);
444 if (datafellows & SSH_BUG_SCANNER) {
445 logit("scanned from %s with %s. Don't panic.",
446 get_remote_ipaddr(), client_version_string);
451 switch (remote_major) {
453 if (remote_minor == 99) {
454 if (options.protocol & SSH_PROTO_2)
460 if (!(options.protocol & SSH_PROTO_1)) {
464 if (remote_minor < 3) {
465 packet_disconnect("Your ssh version is too old and "
466 "is no longer supported. Please install a newer version.");
467 } else if (remote_minor == 3) {
468 /* note that this disables agent-forwarding */
473 if (options.protocol & SSH_PROTO_2) {
482 chop(server_version_string);
483 debug("Local version string %.200s", server_version_string);
486 s = "Protocol major versions differ.\n";
487 (void) atomicio(vwrite, sock_out, s, strlen(s));
490 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
492 server_version_string, client_version_string);
497 /* Destroy the host and server keys. They will no longer be needed. */
499 destroy_sensitive_data(void)
503 if (sensitive_data.server_key) {
504 key_free(sensitive_data.server_key);
505 sensitive_data.server_key = NULL;
507 for (i = 0; i < options.num_host_key_files; i++) {
508 if (sensitive_data.host_keys[i]) {
509 key_free(sensitive_data.host_keys[i]);
510 sensitive_data.host_keys[i] = NULL;
513 sensitive_data.ssh1_host_key = NULL;
514 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
517 /* Demote private to public keys for network child */
519 demote_sensitive_data(void)
524 if (sensitive_data.server_key) {
525 tmp = key_demote(sensitive_data.server_key);
526 key_free(sensitive_data.server_key);
527 sensitive_data.server_key = tmp;
530 for (i = 0; i < options.num_host_key_files; i++) {
531 if (sensitive_data.host_keys[i]) {
532 tmp = key_demote(sensitive_data.host_keys[i]);
533 key_free(sensitive_data.host_keys[i]);
534 sensitive_data.host_keys[i] = tmp;
535 if (tmp->type == KEY_RSA1)
536 sensitive_data.ssh1_host_key = tmp;
540 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
544 privsep_preauth_child(void)
551 /* Enable challenge-response authentication for privilege separation */
552 privsep_challenge_enable();
554 for (i = 0; i < 256; i++)
555 rnd[i] = arc4random();
556 RAND_seed(rnd, sizeof(rnd));
558 /* Demote the private keys to public keys. */
559 demote_sensitive_data();
561 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
562 fatal("Privilege separation user %s does not exist",
564 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
567 /* Change our root directory */
568 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
569 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
571 if (chdir("/") == -1)
572 fatal("chdir(\"/\"): %s", strerror(errno));
574 /* Drop our privileges */
575 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
578 /* XXX not ready, too heavy after chroot */
579 do_setusercontext(pw);
581 gidset[0] = pw->pw_gid;
582 if (setgroups(1, gidset) < 0)
583 fatal("setgroups: %.100s", strerror(errno));
584 permanently_set_uid(pw);
589 privsep_preauth(Authctxt *authctxt)
594 /* Set up unprivileged child process to deal with network data */
595 pmonitor = monitor_init();
596 /* Store a pointer to the kex for later rekeying */
597 pmonitor->m_pkex = &xxx_kex;
601 fatal("fork of unprivileged child failed");
602 } else if (pid != 0) {
603 debug2("Network child is on pid %ld", (long)pid);
605 close(pmonitor->m_recvfd);
606 pmonitor->m_pid = pid;
607 monitor_child_preauth(authctxt, pmonitor);
608 close(pmonitor->m_sendfd);
611 monitor_sync(pmonitor);
613 /* Wait for the child's exit status */
614 while (waitpid(pid, &status, 0) < 0)
621 close(pmonitor->m_sendfd);
623 /* Demote the child */
624 if (getuid() == 0 || geteuid() == 0)
625 privsep_preauth_child();
626 setproctitle("%s", "[net]");
632 privsep_postauth(Authctxt *authctxt)
634 #ifdef DISABLE_FD_PASSING
637 if (authctxt->pw->pw_uid == 0 || options.use_login) {
639 /* File descriptor passing is broken or root login */
644 /* New socket pair */
645 monitor_reinit(pmonitor);
647 pmonitor->m_pid = fork();
648 if (pmonitor->m_pid == -1)
649 fatal("fork of unprivileged child failed");
650 else if (pmonitor->m_pid != 0) {
651 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
652 close(pmonitor->m_recvfd);
653 buffer_clear(&loginmsg);
654 monitor_child_postauth(pmonitor);
660 close(pmonitor->m_sendfd);
662 /* Demote the private keys to public keys. */
663 demote_sensitive_data();
665 /* Drop privileges */
666 do_setusercontext(authctxt->pw);
669 /* It is safe now to apply the key state */
670 monitor_apply_keystate(pmonitor);
673 * Tell the packet layer that authentication was successful, since
674 * this information is not part of the key state.
676 packet_set_authenticated();
680 list_hostkey_types(void)
688 for (i = 0; i < options.num_host_key_files; i++) {
689 Key *key = sensitive_data.host_keys[i];
695 if (buffer_len(&b) > 0)
696 buffer_append(&b, ",", 1);
697 p = key_ssh_name(key);
698 buffer_append(&b, p, strlen(p));
702 buffer_append(&b, "\0", 1);
703 ret = xstrdup(buffer_ptr(&b));
705 debug("list_hostkey_types: %s", ret);
710 get_hostkey_by_type(int type)
714 for (i = 0; i < options.num_host_key_files; i++) {
715 Key *key = sensitive_data.host_keys[i];
716 if (key != NULL && key->type == type)
723 get_hostkey_by_index(int ind)
725 if (ind < 0 || ind >= options.num_host_key_files)
727 return (sensitive_data.host_keys[ind]);
731 get_hostkey_index(Key *key)
735 for (i = 0; i < options.num_host_key_files; i++) {
736 if (key == sensitive_data.host_keys[i])
743 * returns 1 if connection should be dropped, 0 otherwise.
744 * dropping starts at connection #max_startups_begin with a probability
745 * of (max_startups_rate/100). the probability increases linearly until
746 * all connections are dropped for startups > max_startups
749 drop_connection(int startups)
753 if (startups < options.max_startups_begin)
755 if (startups >= options.max_startups)
757 if (options.max_startups_rate == 100)
760 p = 100 - options.max_startups_rate;
761 p *= startups - options.max_startups_begin;
762 p /= options.max_startups - options.max_startups_begin;
763 p += options.max_startups_rate;
764 r = arc4random() % 100;
766 debug("drop_connection: p %d, r %d", p, r);
767 return (r < p) ? 1 : 0;
773 fprintf(stderr, "%s, %s\n",
774 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
776 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
777 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
783 send_rexec_state(int fd, Buffer *conf)
787 debug3("%s: entering fd = %d config len %d", __func__, fd,
791 * Protocol from reexec master to child:
792 * string configuration
793 * u_int ephemeral_key_follows
794 * bignum e (only if ephemeral_key_follows == 1)
800 * string rngseed (only if OpenSSL is not self-seeded)
803 buffer_put_cstring(&m, buffer_ptr(conf));
805 if (sensitive_data.server_key != NULL &&
806 sensitive_data.server_key->type == KEY_RSA1) {
807 buffer_put_int(&m, 1);
808 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
809 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
810 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
811 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
812 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
813 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
815 buffer_put_int(&m, 0);
817 #ifndef OPENSSL_PRNG_ONLY
818 rexec_send_rng_seed(&m);
821 if (ssh_msg_send(fd, 0, &m) == -1)
822 fatal("%s: ssh_msg_send failed", __func__);
826 debug3("%s: done", __func__);
830 recv_rexec_state(int fd, Buffer *conf)
836 debug3("%s: entering fd = %d", __func__, fd);
840 if (ssh_msg_recv(fd, &m) == -1)
841 fatal("%s: ssh_msg_recv failed", __func__);
842 if (buffer_get_char(&m) != 0)
843 fatal("%s: rexec version mismatch", __func__);
845 cp = buffer_get_string(&m, &len);
847 buffer_append(conf, cp, len + 1);
850 if (buffer_get_int(&m)) {
851 if (sensitive_data.server_key != NULL)
852 key_free(sensitive_data.server_key);
853 sensitive_data.server_key = key_new_private(KEY_RSA1);
854 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
855 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
856 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
857 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
858 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
859 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
860 rsa_generate_additional_parameters(
861 sensitive_data.server_key->rsa);
864 #ifndef OPENSSL_PRNG_ONLY
865 rexec_recv_rng_seed(&m);
870 debug3("%s: done", __func__);
874 * Main program for the daemon.
877 main(int ac, char **av)
881 int opt, j, i, fdsetsz, on = 1;
882 int sock_in = -1, sock_out = -1, newsock = -1;
886 struct sockaddr_storage from;
887 const char *remote_ip;
891 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
893 int listen_sock, maxfd;
894 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
898 int ret, key_used = 0;
901 #ifdef HAVE_SECUREWARE
902 (void)set_auth_parameters(ac, av);
904 __progname = ssh_get_progname(av[0]);
907 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
910 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
911 for (i = 0; i < ac; i++)
912 saved_argv[i] = xstrdup(av[i]);
913 saved_argv[i] = NULL;
915 #ifndef HAVE_SETPROCTITLE
916 /* Prepare for later setproctitle emulation */
917 compat_init_setproctitle(ac, av);
921 if (geteuid() == 0 && setgroups(0, NULL) == -1)
922 debug("setgroups(): %.200s", strerror(errno));
924 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
927 /* Initialize configuration options to their default values. */
928 initialize_server_options(&options);
930 /* Parse command-line arguments. */
931 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
934 options.address_family = AF_INET;
937 options.address_family = AF_INET6;
940 config_file_name = optarg;
943 if (debug_flag == 0) {
945 options.log_level = SYSLOG_LEVEL_DEBUG1;
946 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
969 options.log_level = SYSLOG_LEVEL_QUIET;
972 options.server_key_bits = atoi(optarg);
975 options.ports_from_cmdline = 1;
976 if (options.num_ports >= MAX_PORTS) {
977 fprintf(stderr, "too many ports.\n");
980 options.ports[options.num_ports++] = a2port(optarg);
981 if (options.ports[options.num_ports-1] == 0) {
982 fprintf(stderr, "Bad port number.\n");
987 if ((options.login_grace_time = convtime(optarg)) == -1) {
988 fprintf(stderr, "Invalid login grace time.\n");
993 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
994 fprintf(stderr, "Invalid key regeneration interval.\n");
999 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1000 fprintf(stderr, "too many host keys.\n");
1003 options.host_key_files[options.num_host_key_files++] = optarg;
1009 utmp_len = atoi(optarg);
1010 if (utmp_len > MAXHOSTNAMELEN) {
1011 fprintf(stderr, "Invalid utmp length.\n");
1016 line = xstrdup(optarg);
1017 if (process_server_config_line(&options, line,
1018 "command-line", 0) != 0)
1028 if (rexeced_flag || inetd_flag)
1030 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1031 fatal("sshd re-exec requires execution with an absolute path");
1033 closefrom(REEXEC_MIN_FREE_FD);
1035 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1037 SSLeay_add_all_algorithms();
1040 * Force logging to stderr until we have loaded the private host
1041 * key (unless started from inetd)
1043 log_init(__progname,
1044 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1045 SYSLOG_LEVEL_INFO : options.log_level,
1046 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1047 SYSLOG_FACILITY_AUTH : options.log_facility,
1048 log_stderr || !inetd_flag);
1051 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1052 * root's environment
1054 if (getenv("KRB5CCNAME") != NULL)
1055 unsetenv("KRB5CCNAME");
1058 /* Cray can define user privs drop all privs now!
1059 * Not needed on PRIV_SU systems!
1064 sensitive_data.server_key = NULL;
1065 sensitive_data.ssh1_host_key = NULL;
1066 sensitive_data.have_ssh1_key = 0;
1067 sensitive_data.have_ssh2_key = 0;
1069 /* Fetch our configuration */
1072 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1074 load_server_config(config_file_name, &cfg);
1076 parse_server_config(&options,
1077 rexeced_flag ? "rexec" : config_file_name, &cfg);
1084 /* Fill in default values for those options not explicitly set. */
1085 fill_default_server_options(&options);
1087 /* set default channel AF */
1088 channel_set_af(options.address_family);
1090 /* Check that there are no remaining arguments. */
1092 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1096 debug("sshd version %.100s", SSH_RELEASE);
1098 /* load private host keys */
1099 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1101 for (i = 0; i < options.num_host_key_files; i++)
1102 sensitive_data.host_keys[i] = NULL;
1104 for (i = 0; i < options.num_host_key_files; i++) {
1105 key = key_load_private(options.host_key_files[i], "", NULL);
1106 sensitive_data.host_keys[i] = key;
1108 error("Could not load host key: %s",
1109 options.host_key_files[i]);
1110 sensitive_data.host_keys[i] = NULL;
1113 switch (key->type) {
1115 sensitive_data.ssh1_host_key = key;
1116 sensitive_data.have_ssh1_key = 1;
1120 sensitive_data.have_ssh2_key = 1;
1123 debug("private host key: #%d type %d %s", i, key->type,
1126 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1127 logit("Disabling protocol version 1. Could not load host key");
1128 options.protocol &= ~SSH_PROTO_1;
1130 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1131 logit("Disabling protocol version 2. Could not load host key");
1132 options.protocol &= ~SSH_PROTO_2;
1134 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1135 logit("sshd: no hostkeys available -- exiting.");
1139 /* Check certain values for sanity. */
1140 if (options.protocol & SSH_PROTO_1) {
1141 if (options.server_key_bits < 512 ||
1142 options.server_key_bits > 32768) {
1143 fprintf(stderr, "Bad server key size.\n");
1147 * Check that server and host key lengths differ sufficiently. This
1148 * is necessary to make double encryption work with rsaref. Oh, I
1149 * hate software patents. I dont know if this can go? Niels
1151 if (options.server_key_bits >
1152 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1153 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1154 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1155 SSH_KEY_BITS_RESERVED) {
1156 options.server_key_bits =
1157 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1158 SSH_KEY_BITS_RESERVED;
1159 debug("Forcing server key to %d bits to make it differ from host key.",
1160 options.server_key_bits);
1168 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1169 fatal("Privilege separation user %s does not exist",
1171 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1172 (S_ISDIR(st.st_mode) == 0))
1173 fatal("Missing privilege separation directory: %s",
1174 _PATH_PRIVSEP_CHROOT_DIR);
1177 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1178 (st.st_uid != getuid () ||
1179 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1181 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1183 fatal("%s must be owned by root and not group or "
1184 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1187 /* Configuration looks good, so exit if in test mode. */
1192 * Clear out any supplemental groups we may have inherited. This
1193 * prevents inadvertent creation of files with bad modes (in the
1194 * portable version at least, it's certainly possible for PAM
1195 * to create a file, and we can't control the code in every
1196 * module which might be used).
1198 if (setgroups(0, NULL) < 0)
1199 debug("setgroups() failed: %.200s", strerror(errno));
1202 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1203 for (i = 0; i < rexec_argc; i++) {
1204 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1205 rexec_argv[i] = saved_argv[i];
1207 rexec_argv[rexec_argc] = "-R";
1208 rexec_argv[rexec_argc + 1] = NULL;
1211 /* Initialize the log (it is reinitialized below in case we forked). */
1212 if (debug_flag && (!inetd_flag || rexeced_flag))
1214 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1217 * If not in debugging mode, and not started from inetd, disconnect
1218 * from the controlling terminal, and fork. The original process
1221 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1224 #endif /* TIOCNOTTY */
1225 if (daemon(0, 0) < 0)
1226 fatal("daemon() failed: %.200s", strerror(errno));
1228 /* Disconnect from the controlling tty. */
1230 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1232 (void) ioctl(fd, TIOCNOTTY, NULL);
1235 #endif /* TIOCNOTTY */
1237 /* Reinitialize the log (because of the fork above). */
1238 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1240 /* Initialize the random number generator. */
1243 /* Chdir to the root directory so that the current disk can be
1244 unmounted if desired. */
1247 /* ignore SIGPIPE */
1248 signal(SIGPIPE, SIG_IGN);
1250 /* Start listening for a socket, unless started from inetd. */
1256 close(REEXEC_CONFIG_PASS_FD);
1257 sock_in = sock_out = dup(STDIN_FILENO);
1259 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1260 close(REEXEC_STARTUP_PIPE_FD);
1263 sock_in = dup(STDIN_FILENO);
1264 sock_out = dup(STDOUT_FILENO);
1267 * We intentionally do not close the descriptors 0, 1, and 2
1268 * as our code for setting the descriptors won't work if
1269 * ttyfd happens to be one of those.
1271 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1272 dup2(fd, STDIN_FILENO);
1273 dup2(fd, STDOUT_FILENO);
1274 if (fd > STDOUT_FILENO)
1277 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1278 if ((options.protocol & SSH_PROTO_1) &&
1279 sensitive_data.server_key == NULL)
1280 generate_ephemeral_server_key();
1282 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1283 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1285 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1286 fatal("Too many listen sockets. "
1287 "Enlarge MAX_LISTEN_SOCKS");
1288 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1289 ntop, sizeof(ntop), strport, sizeof(strport),
1290 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1291 error("getnameinfo failed: %.100s",
1292 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1296 /* Create socket for listening. */
1297 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1299 if (listen_sock < 0) {
1300 /* kernel may not support ipv6 */
1301 verbose("socket: %.100s", strerror(errno));
1304 if (set_nonblock(listen_sock) == -1) {
1309 * Set socket options.
1310 * Allow local port reuse in TIME_WAIT.
1312 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1313 &on, sizeof(on)) == -1)
1314 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1316 debug("Bind to port %s on %s.", strport, ntop);
1318 /* Bind the socket to the desired port. */
1319 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1321 error("Bind to port %s on %s failed: %.200s.",
1322 strport, ntop, strerror(errno));
1326 listen_socks[num_listen_socks] = listen_sock;
1329 /* Start listening on the port. */
1330 logit("Server listening on %s port %s.", ntop, strport);
1331 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1332 fatal("listen: %.100s", strerror(errno));
1335 freeaddrinfo(options.listen_addrs);
1337 if (!num_listen_socks)
1338 fatal("Cannot bind any address.");
1340 if (options.protocol & SSH_PROTO_1)
1341 generate_ephemeral_server_key();
1344 * Arrange to restart on SIGHUP. The handler needs
1347 signal(SIGHUP, sighup_handler);
1349 signal(SIGTERM, sigterm_handler);
1350 signal(SIGQUIT, sigterm_handler);
1352 /* Arrange SIGCHLD to be caught. */
1353 signal(SIGCHLD, main_sigchld_handler);
1355 /* Write out the pid file after the sigterm handler is setup */
1358 * Record our pid in /var/run/sshd.pid to make it
1359 * easier to kill the correct sshd. We don't want to
1360 * do this before the bind above because the bind will
1361 * fail if there already is a daemon, and this will
1362 * overwrite any old pid in the file.
1364 f = fopen(options.pid_file, "wb");
1366 error("Couldn't create pid file \"%s\": %s",
1367 options.pid_file, strerror(errno));
1369 fprintf(f, "%ld\n", (long) getpid());
1374 /* setup fd set for listen */
1377 for (i = 0; i < num_listen_socks; i++)
1378 if (listen_socks[i] > maxfd)
1379 maxfd = listen_socks[i];
1380 /* pipes connected to unauthenticated childs */
1381 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1382 for (i = 0; i < options.max_startups; i++)
1383 startup_pipes[i] = -1;
1386 * Stay listening for connections until the system crashes or
1387 * the daemon is killed with a signal.
1390 if (received_sighup)
1394 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1395 fdset = (fd_set *)xmalloc(fdsetsz);
1396 memset(fdset, 0, fdsetsz);
1398 for (i = 0; i < num_listen_socks; i++)
1399 FD_SET(listen_socks[i], fdset);
1400 for (i = 0; i < options.max_startups; i++)
1401 if (startup_pipes[i] != -1)
1402 FD_SET(startup_pipes[i], fdset);
1404 /* Wait in select until there is a connection. */
1405 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1406 if (ret < 0 && errno != EINTR)
1407 error("select: %.100s", strerror(errno));
1408 if (received_sigterm) {
1409 logit("Received signal %d; terminating.",
1410 (int) received_sigterm);
1411 close_listen_socks();
1412 unlink(options.pid_file);
1415 if (key_used && key_do_regen) {
1416 generate_ephemeral_server_key();
1423 for (i = 0; i < options.max_startups; i++)
1424 if (startup_pipes[i] != -1 &&
1425 FD_ISSET(startup_pipes[i], fdset)) {
1427 * the read end of the pipe is ready
1428 * if the child has closed the pipe
1429 * after successful authentication
1430 * or if the child has died
1432 close(startup_pipes[i]);
1433 startup_pipes[i] = -1;
1436 for (i = 0; i < num_listen_socks; i++) {
1437 if (!FD_ISSET(listen_socks[i], fdset))
1439 fromlen = sizeof(from);
1440 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1443 if (errno != EINTR && errno != EWOULDBLOCK)
1444 error("accept: %.100s", strerror(errno));
1447 if (unset_nonblock(newsock) == -1) {
1451 if (drop_connection(startups) == 1) {
1452 debug("drop connection #%d", startups);
1456 if (pipe(startup_p) == -1) {
1461 if (rexec_flag && socketpair(AF_UNIX,
1462 SOCK_STREAM, 0, config_s) == -1) {
1463 error("reexec socketpair: %s",
1466 close(startup_p[0]);
1467 close(startup_p[1]);
1471 for (j = 0; j < options.max_startups; j++)
1472 if (startup_pipes[j] == -1) {
1473 startup_pipes[j] = startup_p[0];
1474 if (maxfd < startup_p[0])
1475 maxfd = startup_p[0];
1481 * Got connection. Fork a child to handle it, unless
1482 * we are in debugging mode.
1486 * In debugging mode. Close the listening
1487 * socket, and start processing the
1488 * connection without forking.
1490 debug("Server will not fork when running in debugging mode.");
1491 close_listen_socks();
1494 close(startup_p[0]);
1495 close(startup_p[1]);
1499 send_rexec_state(config_s[0],
1506 * Normal production daemon. Fork, and have
1507 * the child process the connection. The
1508 * parent continues listening.
1510 if ((pid = fork()) == 0) {
1512 * Child. Close the listening and max_startup
1513 * sockets. Start using the accepted socket.
1514 * Reinitialize logging (since our pid has
1515 * changed). We break out of the loop to handle
1518 startup_pipe = startup_p[1];
1519 close_startup_pipes();
1520 close_listen_socks();
1523 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1530 /* Parent. Stay in the loop. */
1532 error("fork: %.100s", strerror(errno));
1534 debug("Forked child %ld.", (long)pid);
1536 close(startup_p[1]);
1539 send_rexec_state(config_s[0], &cfg);
1544 /* Mark that the key has been used (it was "given" to the child). */
1545 if ((options.protocol & SSH_PROTO_1) &&
1547 /* Schedule server key regeneration alarm. */
1548 signal(SIGALRM, key_regeneration_alarm);
1549 alarm(options.key_regeneration_time);
1555 /* Close the new socket (the child is now taking care of it). */
1558 /* child process check (or debug mode) */
1559 if (num_listen_socks < 0)
1564 /* This is the child processing a new connection. */
1565 setproctitle("%s", "[accepted]");
1568 * Create a new session and process group since the 4.4BSD
1569 * setlogin() affects the entire process group. We don't
1570 * want the child to be able to affect the parent.
1572 #if !defined(SSHD_ACQUIRES_CTTY)
1574 * If setsid is called, on some platforms sshd will later acquire a
1575 * controlling terminal which will result in "could not set
1576 * controlling tty" errors.
1578 if (!debug_flag && !inetd_flag && setsid() < 0)
1579 error("setsid: %.100s", strerror(errno));
1585 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1586 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1587 dup2(newsock, STDIN_FILENO);
1588 dup2(STDIN_FILENO, STDOUT_FILENO);
1589 if (startup_pipe == -1)
1590 close(REEXEC_STARTUP_PIPE_FD);
1592 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1594 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1596 if (startup_pipe != -1)
1597 close(startup_pipe);
1599 execv(rexec_argv[0], rexec_argv);
1601 /* Reexec has failed, fall back and continue */
1602 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1603 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1604 log_init(__progname, options.log_level,
1605 options.log_facility, log_stderr);
1608 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1610 close(REEXEC_CONFIG_PASS_FD);
1611 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1612 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1613 dup2(fd, STDIN_FILENO);
1614 dup2(fd, STDOUT_FILENO);
1615 if (fd > STDERR_FILENO)
1618 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1619 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1623 * Disable the key regeneration alarm. We will not regenerate the
1624 * key since we are no longer in a position to give it to anyone. We
1625 * will not restart on SIGHUP since it no longer makes sense.
1628 signal(SIGALRM, SIG_DFL);
1629 signal(SIGHUP, SIG_DFL);
1630 signal(SIGTERM, SIG_DFL);
1631 signal(SIGQUIT, SIG_DFL);
1632 signal(SIGCHLD, SIG_DFL);
1633 signal(SIGINT, SIG_DFL);
1636 * Register our connection. This turns encryption off because we do
1639 packet_set_connection(sock_in, sock_out);
1640 packet_set_server();
1642 /* Set SO_KEEPALIVE if requested. */
1643 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1644 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1645 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1647 if ((remote_port = get_remote_port()) < 0) {
1648 debug("get_remote_port failed");
1653 * We use get_canonical_hostname with usedns = 0 instead of
1654 * get_remote_ipaddr here so IP options will be checked.
1656 remote_ip = get_canonical_hostname(0);
1658 #ifdef SSH_AUDIT_EVENTS
1659 audit_connection_from(remote_ip, remote_port);
1662 /* Check whether logins are denied from this host. */
1663 if (packet_connection_is_on_socket()) {
1664 struct request_info req;
1666 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1669 if (!hosts_access(&req)) {
1670 debug("Connection refused by tcp wrapper");
1673 fatal("libwrap refuse returns");
1676 #endif /* LIBWRAP */
1678 /* Log the connection. */
1679 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1682 * We don't want to listen forever unless the other side
1683 * successfully authenticates itself. So we set up an alarm which is
1684 * cleared after successful authentication. A limit of zero
1685 * indicates no limit. Note that we don't set the alarm in debugging
1686 * mode; it is just annoying to have the server exit just when you
1687 * are about to discover the bug.
1689 signal(SIGALRM, grace_alarm_handler);
1691 alarm(options.login_grace_time);
1693 sshd_exchange_identification(sock_in, sock_out);
1695 packet_set_nonblocking();
1697 /* allocate authentication context */
1698 authctxt = xmalloc(sizeof(*authctxt));
1699 memset(authctxt, 0, sizeof(*authctxt));
1701 authctxt->loginmsg = &loginmsg;
1703 /* XXX global for cleanup, access from other modules */
1704 the_authctxt = authctxt;
1706 /* prepare buffer to collect messages to display to user after login */
1707 buffer_init(&loginmsg);
1710 if (privsep_preauth(authctxt) == 1)
1713 /* perform the key exchange */
1714 /* authenticate user and start session */
1717 do_authentication2(authctxt);
1720 do_authentication(authctxt);
1723 * If we use privilege separation, the unprivileged child transfers
1724 * the current keystate and exits
1727 mm_send_keystate(pmonitor);
1733 * Cancel the alarm we set to limit the time taken for
1737 signal(SIGALRM, SIG_DFL);
1738 if (startup_pipe != -1) {
1739 close(startup_pipe);
1743 #ifdef SSH_AUDIT_EVENTS
1744 audit_event(SSH_AUTH_SUCCESS);
1748 * In privilege separation, we fork another child and prepare
1749 * file descriptor passing.
1752 privsep_postauth(authctxt);
1753 /* the monitor process [priv] will not return */
1755 destroy_sensitive_data();
1758 /* Start session. */
1759 do_authenticated(authctxt);
1761 /* The connection has been terminated. */
1762 verbose("Closing connection to %.100s", remote_ip);
1765 if (options.use_pam)
1767 #endif /* USE_PAM */
1769 #ifdef SSH_AUDIT_EVENTS
1770 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1782 * Decrypt session_key_int using our private server key and private host key
1783 * (key with larger modulus first).
1786 ssh1_session_key(BIGNUM *session_key_int)
1790 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1791 /* Server key has bigger modulus. */
1792 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1793 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1794 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1795 get_remote_ipaddr(),
1796 BN_num_bits(sensitive_data.server_key->rsa->n),
1797 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1798 SSH_KEY_BITS_RESERVED);
1800 if (rsa_private_decrypt(session_key_int, session_key_int,
1801 sensitive_data.server_key->rsa) <= 0)
1803 if (rsa_private_decrypt(session_key_int, session_key_int,
1804 sensitive_data.ssh1_host_key->rsa) <= 0)
1807 /* Host key has bigger modulus (or they are equal). */
1808 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1809 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1810 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1811 get_remote_ipaddr(),
1812 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1813 BN_num_bits(sensitive_data.server_key->rsa->n),
1814 SSH_KEY_BITS_RESERVED);
1816 if (rsa_private_decrypt(session_key_int, session_key_int,
1817 sensitive_data.ssh1_host_key->rsa) < 0)
1819 if (rsa_private_decrypt(session_key_int, session_key_int,
1820 sensitive_data.server_key->rsa) < 0)
1833 BIGNUM *session_key_int;
1834 u_char session_key[SSH_SESSION_KEY_LENGTH];
1836 u_int cipher_type, auth_mask, protocol_flags;
1840 * Generate check bytes that the client must send back in the user
1841 * packet in order for it to be accepted; this is used to defy ip
1842 * spoofing attacks. Note that this only works against somebody
1843 * doing IP spoofing from a remote machine; any machine on the local
1844 * network can still see outgoing packets and catch the random
1845 * cookie. This only affects rhosts authentication, and this is one
1846 * of the reasons why it is inherently insecure.
1848 for (i = 0; i < 8; i++) {
1851 cookie[i] = rnd & 0xff;
1856 * Send our public key. We include in the packet 64 bits of random
1857 * data that must be matched in the reply in order to prevent IP
1860 packet_start(SSH_SMSG_PUBLIC_KEY);
1861 for (i = 0; i < 8; i++)
1862 packet_put_char(cookie[i]);
1864 /* Store our public server RSA key. */
1865 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1866 packet_put_bignum(sensitive_data.server_key->rsa->e);
1867 packet_put_bignum(sensitive_data.server_key->rsa->n);
1869 /* Store our public host RSA key. */
1870 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1871 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1872 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1874 /* Put protocol flags. */
1875 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1877 /* Declare which ciphers we support. */
1878 packet_put_int(cipher_mask_ssh1(0));
1880 /* Declare supported authentication types. */
1882 if (options.rhosts_rsa_authentication)
1883 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1884 if (options.rsa_authentication)
1885 auth_mask |= 1 << SSH_AUTH_RSA;
1886 if (options.challenge_response_authentication == 1)
1887 auth_mask |= 1 << SSH_AUTH_TIS;
1888 if (options.password_authentication)
1889 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1890 packet_put_int(auth_mask);
1892 /* Send the packet and wait for it to be sent. */
1894 packet_write_wait();
1896 debug("Sent %d bit server key and %d bit host key.",
1897 BN_num_bits(sensitive_data.server_key->rsa->n),
1898 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1900 /* Read clients reply (cipher type and session key). */
1901 packet_read_expect(SSH_CMSG_SESSION_KEY);
1903 /* Get cipher type and check whether we accept this. */
1904 cipher_type = packet_get_char();
1906 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1907 packet_disconnect("Warning: client selects unsupported cipher.");
1909 /* Get check bytes from the packet. These must match those we
1910 sent earlier with the public key packet. */
1911 for (i = 0; i < 8; i++)
1912 if (cookie[i] != packet_get_char())
1913 packet_disconnect("IP Spoofing check bytes do not match.");
1915 debug("Encryption type: %.200s", cipher_name(cipher_type));
1917 /* Get the encrypted integer. */
1918 if ((session_key_int = BN_new()) == NULL)
1919 fatal("do_ssh1_kex: BN_new failed");
1920 packet_get_bignum(session_key_int);
1922 protocol_flags = packet_get_int();
1923 packet_set_protocol_flags(protocol_flags);
1926 /* Decrypt session_key_int using host/server keys */
1927 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1930 * Extract session key from the decrypted integer. The key is in the
1931 * least significant 256 bits of the integer; the first byte of the
1932 * key is in the highest bits.
1935 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1936 len = BN_num_bytes(session_key_int);
1937 if (len < 0 || (u_int)len > sizeof(session_key)) {
1938 error("do_connection: bad session key len from %s: "
1939 "session_key_int %d > sizeof(session_key) %lu",
1940 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1943 memset(session_key, 0, sizeof(session_key));
1944 BN_bn2bin(session_key_int,
1945 session_key + sizeof(session_key) - len);
1947 derive_ssh1_session_id(
1948 sensitive_data.ssh1_host_key->rsa->n,
1949 sensitive_data.server_key->rsa->n,
1950 cookie, session_id);
1952 * Xor the first 16 bytes of the session key with the
1955 for (i = 0; i < 16; i++)
1956 session_key[i] ^= session_id[i];
1960 int bytes = BN_num_bytes(session_key_int);
1961 u_char *buf = xmalloc(bytes);
1964 logit("do_connection: generating a fake encryption key");
1965 BN_bn2bin(session_key_int, buf);
1967 MD5_Update(&md, buf, bytes);
1968 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1969 MD5_Final(session_key, &md);
1971 MD5_Update(&md, session_key, 16);
1972 MD5_Update(&md, buf, bytes);
1973 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1974 MD5_Final(session_key + 16, &md);
1975 memset(buf, 0, bytes);
1977 for (i = 0; i < 16; i++)
1978 session_id[i] = session_key[i] ^ session_key[i + 16];
1980 /* Destroy the private and public keys. No longer. */
1981 destroy_sensitive_data();
1984 mm_ssh1_session_id(session_id);
1986 /* Destroy the decrypted integer. It is no longer needed. */
1987 BN_clear_free(session_key_int);
1989 /* Set the session key. From this on all communications will be encrypted. */
1990 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1992 /* Destroy our copy of the session key. It is no longer needed. */
1993 memset(session_key, 0, sizeof(session_key));
1995 debug("Received session key; encryption turned on.");
1997 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1998 packet_start(SSH_SMSG_SUCCESS);
2000 packet_write_wait();
2004 * SSH2 key exchange: diffie-hellman-group1-sha1
2011 if (options.ciphers != NULL) {
2012 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2013 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2015 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2016 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2017 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2018 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2020 if (options.macs != NULL) {
2021 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2022 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2024 if (options.compression == COMP_NONE) {
2025 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2026 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2027 } else if (options.compression == COMP_DELAYED) {
2028 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2029 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2032 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2034 /* start key exchange */
2035 kex = kex_setup(myproposal);
2036 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2037 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2038 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2040 kex->client_version_string=client_version_string;
2041 kex->server_version_string=server_version_string;
2042 kex->load_host_key=&get_hostkey_by_type;
2043 kex->host_key_index=&get_hostkey_index;
2047 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2049 session_id2 = kex->session_id;
2050 session_id2_len = kex->session_id_len;
2053 /* send 1st encrypted/maced/compressed message */
2054 packet_start(SSH2_MSG_IGNORE);
2055 packet_put_cstring("markus");
2057 packet_write_wait();
2062 /* server specific fatal cleanup */
2067 do_cleanup(the_authctxt);
2068 #ifdef SSH_AUDIT_EVENTS
2069 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2070 if (!use_privsep || mm_is_monitor())
2071 audit_event(SSH_CONNECTION_ABANDON);