1 /* $OpenBSD: sshd.c,v 1.334 2006/07/08 21:47:12 stevesk Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This program is the ssh daemon. It listens for connections from clients,
7 * and performs authentication, executes use commands or shell, and forwards
8 * information to/from the application to the user client over an encrypted
9 * connection. This can also handle forwarding of X11, TCP/IP, and
10 * authentication agent connections.
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
18 * SSH2 implementation:
19 * Privilege Separation:
21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22 * Copyright (c) 2002 Niels Provos. All rights reserved.
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
47 #include <sys/types.h>
48 #ifdef HAVE_SYS_STAT_H
49 # include <sys/stat.h>
51 #include <sys/ioctl.h>
52 #include <sys/socket.h>
61 #include <openssl/dh.h>
62 #include <openssl/bn.h>
63 #include <openssl/md5.h>
64 #include <openssl/rand.h>
65 #ifdef HAVE_SECUREWARE
66 #include <sys/security.h>
87 #include "myproposal.h"
89 #include "pathnames.h"
98 #include "monitor_mm.h"
100 #include "monitor_wrap.h"
101 #include "monitor_fdpass.h"
107 int allow_severity = LOG_INFO;
108 int deny_severity = LOG_WARNING;
116 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
117 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
118 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
119 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
121 extern char *__progname;
123 /* Server configuration options. */
124 ServerOptions options;
126 /* Name of the server configuration file. */
127 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
130 * Debug mode flag. This can be set on the command line. If debug
131 * mode is enabled, extra debugging output will be sent to the system
132 * log, the daemon will not go to background, and will exit after processing
133 * the first connection.
137 /* Flag indicating that the daemon should only test the configuration and keys. */
140 /* Flag indicating that the daemon is being started from inetd. */
143 /* Flag indicating that sshd should not detach and become a daemon. */
144 int no_daemon_flag = 0;
146 /* debug goes to stderr unless inetd_flag is set */
149 /* Saved arguments to main(). */
154 int rexeced_flag = 0;
160 * The sockets that the server is listening; this is used in the SIGHUP
163 #define MAX_LISTEN_SOCKS 16
164 int listen_socks[MAX_LISTEN_SOCKS];
165 int num_listen_socks = 0;
168 * the client's version string, passed by sshd2 in compat mode. if != NULL,
169 * sshd will skip the version-number exchange
171 char *client_version_string = NULL;
172 char *server_version_string = NULL;
174 /* for rekeying XXX fixme */
178 * Any really sensitive data in the application is contained in this
179 * structure. The idea is that this structure could be locked into memory so
180 * that the pages do not get written into swap. However, there are some
181 * problems. The private key contains BIGNUMs, and we do not (in principle)
182 * have access to the internals of them, and locking just the structure is
183 * not very useful. Currently, memory locking is not implemented.
186 Key *server_key; /* ephemeral server key */
187 Key *ssh1_host_key; /* ssh1 host key */
188 Key **host_keys; /* all private host keys */
191 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
195 * Flag indicating whether the RSA server key needs to be regenerated.
196 * Is set in the SIGALRM handler and cleared when the key is regenerated.
198 static volatile sig_atomic_t key_do_regen = 0;
200 /* This is set to true when a signal is received. */
201 static volatile sig_atomic_t received_sighup = 0;
202 static volatile sig_atomic_t received_sigterm = 0;
204 /* session identifier, used by RSA-auth */
205 u_char session_id[16];
208 u_char *session_id2 = NULL;
209 u_int session_id2_len = 0;
211 /* record remote hostname or ip */
212 u_int utmp_len = MAXHOSTNAMELEN;
214 /* options.max_startup sized array of fd ints */
215 int *startup_pipes = NULL;
216 int startup_pipe; /* in child */
218 /* variables used for privilege separation */
220 struct monitor *pmonitor = NULL;
222 /* global authentication context */
223 Authctxt *the_authctxt = NULL;
225 /* message to be displayed after login */
228 /* Prototypes for various functions defined later in this file. */
229 void destroy_sensitive_data(void);
230 void demote_sensitive_data(void);
232 static void do_ssh1_kex(void);
233 static void do_ssh2_kex(void);
236 * Close all listening sockets
239 close_listen_socks(void)
243 for (i = 0; i < num_listen_socks; i++)
244 close(listen_socks[i]);
245 num_listen_socks = -1;
249 close_startup_pipes(void)
254 for (i = 0; i < options.max_startups; i++)
255 if (startup_pipes[i] != -1)
256 close(startup_pipes[i]);
260 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
261 * the effect is to reread the configuration file (and to regenerate
267 sighup_handler(int sig)
269 int save_errno = errno;
272 signal(SIGHUP, sighup_handler);
277 * Called from the main program after receiving SIGHUP.
278 * Restarts the server.
283 logit("Received SIGHUP; restarting.");
284 close_listen_socks();
285 close_startup_pipes();
286 execv(saved_argv[0], saved_argv);
287 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
293 * Generic signal handler for terminating signals in the master daemon.
297 sigterm_handler(int sig)
299 received_sigterm = sig;
303 * SIGCHLD handler. This is called whenever a child dies. This will then
304 * reap any zombies left by exited children.
308 main_sigchld_handler(int sig)
310 int save_errno = errno;
314 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
315 (pid < 0 && errno == EINTR))
318 signal(SIGCHLD, main_sigchld_handler);
323 * Signal handler for the alarm after the login grace period has expired.
327 grace_alarm_handler(int sig)
329 /* XXX no idea how fix this signal handler */
331 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
332 kill(pmonitor->m_pid, SIGALRM);
334 /* Log error and exit. */
335 fatal("Timeout before authentication for %s", get_remote_ipaddr());
339 * Signal handler for the key regeneration alarm. Note that this
340 * alarm only occurs in the daemon waiting for connections, and it does not
341 * do anything with the private key or random state before forking.
342 * Thus there should be no concurrency control/asynchronous execution
346 generate_ephemeral_server_key(void)
351 verbose("Generating %s%d bit RSA key.",
352 sensitive_data.server_key ? "new " : "", options.server_key_bits);
353 if (sensitive_data.server_key != NULL)
354 key_free(sensitive_data.server_key);
355 sensitive_data.server_key = key_generate(KEY_RSA1,
356 options.server_key_bits);
357 verbose("RSA key generation complete.");
359 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
362 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
370 key_regeneration_alarm(int sig)
372 int save_errno = errno;
374 signal(SIGALRM, SIG_DFL);
380 sshd_exchange_identification(int sock_in, int sock_out)
384 int remote_major, remote_minor;
387 char buf[256]; /* Must not be larger than remote_version. */
388 char remote_version[256]; /* Must be at least as big as buf. */
390 if ((options.protocol & SSH_PROTO_1) &&
391 (options.protocol & SSH_PROTO_2)) {
392 major = PROTOCOL_MAJOR_1;
394 } else if (options.protocol & SSH_PROTO_2) {
395 major = PROTOCOL_MAJOR_2;
396 minor = PROTOCOL_MINOR_2;
398 major = PROTOCOL_MAJOR_1;
399 minor = PROTOCOL_MINOR_1;
401 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
402 server_version_string = xstrdup(buf);
404 /* Send our protocol version identification. */
405 if (atomicio(vwrite, sock_out, server_version_string,
406 strlen(server_version_string))
407 != strlen(server_version_string)) {
408 logit("Could not write ident string to %s", get_remote_ipaddr());
412 /* Read other sides version identification. */
413 memset(buf, 0, sizeof(buf));
414 for (i = 0; i < sizeof(buf) - 1; i++) {
415 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
416 logit("Did not receive identification string from %s",
417 get_remote_ipaddr());
420 if (buf[i] == '\r') {
422 /* Kludge for F-Secure Macintosh < 1.0.2 */
424 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
428 if (buf[i] == '\n') {
433 buf[sizeof(buf) - 1] = 0;
434 client_version_string = xstrdup(buf);
437 * Check that the versions match. In future this might accept
438 * several versions and set appropriate flags to handle them.
440 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
441 &remote_major, &remote_minor, remote_version) != 3) {
442 s = "Protocol mismatch.\n";
443 (void) atomicio(vwrite, sock_out, s, strlen(s));
446 logit("Bad protocol version identification '%.100s' from %s",
447 client_version_string, get_remote_ipaddr());
450 debug("Client protocol version %d.%d; client software version %.100s",
451 remote_major, remote_minor, remote_version);
453 compat_datafellows(remote_version);
455 if (datafellows & SSH_BUG_PROBE) {
456 logit("probed from %s with %s. Don't panic.",
457 get_remote_ipaddr(), client_version_string);
461 if (datafellows & SSH_BUG_SCANNER) {
462 logit("scanned from %s with %s. Don't panic.",
463 get_remote_ipaddr(), client_version_string);
468 switch (remote_major) {
470 if (remote_minor == 99) {
471 if (options.protocol & SSH_PROTO_2)
477 if (!(options.protocol & SSH_PROTO_1)) {
481 if (remote_minor < 3) {
482 packet_disconnect("Your ssh version is too old and "
483 "is no longer supported. Please install a newer version.");
484 } else if (remote_minor == 3) {
485 /* note that this disables agent-forwarding */
490 if (options.protocol & SSH_PROTO_2) {
499 chop(server_version_string);
500 debug("Local version string %.200s", server_version_string);
503 s = "Protocol major versions differ.\n";
504 (void) atomicio(vwrite, sock_out, s, strlen(s));
507 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
509 server_version_string, client_version_string);
514 /* Destroy the host and server keys. They will no longer be needed. */
516 destroy_sensitive_data(void)
520 if (sensitive_data.server_key) {
521 key_free(sensitive_data.server_key);
522 sensitive_data.server_key = NULL;
524 for (i = 0; i < options.num_host_key_files; i++) {
525 if (sensitive_data.host_keys[i]) {
526 key_free(sensitive_data.host_keys[i]);
527 sensitive_data.host_keys[i] = NULL;
530 sensitive_data.ssh1_host_key = NULL;
531 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
534 /* Demote private to public keys for network child */
536 demote_sensitive_data(void)
541 if (sensitive_data.server_key) {
542 tmp = key_demote(sensitive_data.server_key);
543 key_free(sensitive_data.server_key);
544 sensitive_data.server_key = tmp;
547 for (i = 0; i < options.num_host_key_files; i++) {
548 if (sensitive_data.host_keys[i]) {
549 tmp = key_demote(sensitive_data.host_keys[i]);
550 key_free(sensitive_data.host_keys[i]);
551 sensitive_data.host_keys[i] = tmp;
552 if (tmp->type == KEY_RSA1)
553 sensitive_data.ssh1_host_key = tmp;
557 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
561 privsep_preauth_child(void)
568 /* Enable challenge-response authentication for privilege separation */
569 privsep_challenge_enable();
571 for (i = 0; i < 256; i++)
572 rnd[i] = arc4random();
573 RAND_seed(rnd, sizeof(rnd));
575 /* Demote the private keys to public keys. */
576 demote_sensitive_data();
578 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
579 fatal("Privilege separation user %s does not exist",
581 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
584 /* Change our root directory */
585 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
586 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
588 if (chdir("/") == -1)
589 fatal("chdir(\"/\"): %s", strerror(errno));
591 /* Drop our privileges */
592 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
595 /* XXX not ready, too heavy after chroot */
596 do_setusercontext(pw);
598 gidset[0] = pw->pw_gid;
599 if (setgroups(1, gidset) < 0)
600 fatal("setgroups: %.100s", strerror(errno));
601 permanently_set_uid(pw);
606 privsep_preauth(Authctxt *authctxt)
611 /* Set up unprivileged child process to deal with network data */
612 pmonitor = monitor_init();
613 /* Store a pointer to the kex for later rekeying */
614 pmonitor->m_pkex = &xxx_kex;
618 fatal("fork of unprivileged child failed");
619 } else if (pid != 0) {
620 debug2("Network child is on pid %ld", (long)pid);
622 close(pmonitor->m_recvfd);
623 pmonitor->m_pid = pid;
624 monitor_child_preauth(authctxt, pmonitor);
625 close(pmonitor->m_sendfd);
628 monitor_sync(pmonitor);
630 /* Wait for the child's exit status */
631 while (waitpid(pid, &status, 0) < 0)
638 close(pmonitor->m_sendfd);
640 /* Demote the child */
641 if (getuid() == 0 || geteuid() == 0)
642 privsep_preauth_child();
643 setproctitle("%s", "[net]");
649 privsep_postauth(Authctxt *authctxt)
651 #ifdef DISABLE_FD_PASSING
654 if (authctxt->pw->pw_uid == 0 || options.use_login) {
656 /* File descriptor passing is broken or root login */
661 /* New socket pair */
662 monitor_reinit(pmonitor);
664 pmonitor->m_pid = fork();
665 if (pmonitor->m_pid == -1)
666 fatal("fork of unprivileged child failed");
667 else if (pmonitor->m_pid != 0) {
668 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
669 close(pmonitor->m_recvfd);
670 buffer_clear(&loginmsg);
671 monitor_child_postauth(pmonitor);
677 close(pmonitor->m_sendfd);
679 /* Demote the private keys to public keys. */
680 demote_sensitive_data();
682 /* Drop privileges */
683 do_setusercontext(authctxt->pw);
686 /* It is safe now to apply the key state */
687 monitor_apply_keystate(pmonitor);
690 * Tell the packet layer that authentication was successful, since
691 * this information is not part of the key state.
693 packet_set_authenticated();
697 list_hostkey_types(void)
705 for (i = 0; i < options.num_host_key_files; i++) {
706 Key *key = sensitive_data.host_keys[i];
712 if (buffer_len(&b) > 0)
713 buffer_append(&b, ",", 1);
714 p = key_ssh_name(key);
715 buffer_append(&b, p, strlen(p));
719 buffer_append(&b, "\0", 1);
720 ret = xstrdup(buffer_ptr(&b));
722 debug("list_hostkey_types: %s", ret);
727 get_hostkey_by_type(int type)
731 for (i = 0; i < options.num_host_key_files; i++) {
732 Key *key = sensitive_data.host_keys[i];
733 if (key != NULL && key->type == type)
740 get_hostkey_by_index(int ind)
742 if (ind < 0 || ind >= options.num_host_key_files)
744 return (sensitive_data.host_keys[ind]);
748 get_hostkey_index(Key *key)
752 for (i = 0; i < options.num_host_key_files; i++) {
753 if (key == sensitive_data.host_keys[i])
760 * returns 1 if connection should be dropped, 0 otherwise.
761 * dropping starts at connection #max_startups_begin with a probability
762 * of (max_startups_rate/100). the probability increases linearly until
763 * all connections are dropped for startups > max_startups
766 drop_connection(int startups)
770 if (startups < options.max_startups_begin)
772 if (startups >= options.max_startups)
774 if (options.max_startups_rate == 100)
777 p = 100 - options.max_startups_rate;
778 p *= startups - options.max_startups_begin;
779 p /= options.max_startups - options.max_startups_begin;
780 p += options.max_startups_rate;
781 r = arc4random() % 100;
783 debug("drop_connection: p %d, r %d", p, r);
784 return (r < p) ? 1 : 0;
790 fprintf(stderr, "%s, %s\n",
791 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
793 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
794 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
800 send_rexec_state(int fd, Buffer *conf)
804 debug3("%s: entering fd = %d config len %d", __func__, fd,
808 * Protocol from reexec master to child:
809 * string configuration
810 * u_int ephemeral_key_follows
811 * bignum e (only if ephemeral_key_follows == 1)
817 * string rngseed (only if OpenSSL is not self-seeded)
820 buffer_put_cstring(&m, buffer_ptr(conf));
822 if (sensitive_data.server_key != NULL &&
823 sensitive_data.server_key->type == KEY_RSA1) {
824 buffer_put_int(&m, 1);
825 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
826 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
827 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
828 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
829 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
830 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
832 buffer_put_int(&m, 0);
834 #ifndef OPENSSL_PRNG_ONLY
835 rexec_send_rng_seed(&m);
838 if (ssh_msg_send(fd, 0, &m) == -1)
839 fatal("%s: ssh_msg_send failed", __func__);
843 debug3("%s: done", __func__);
847 recv_rexec_state(int fd, Buffer *conf)
853 debug3("%s: entering fd = %d", __func__, fd);
857 if (ssh_msg_recv(fd, &m) == -1)
858 fatal("%s: ssh_msg_recv failed", __func__);
859 if (buffer_get_char(&m) != 0)
860 fatal("%s: rexec version mismatch", __func__);
862 cp = buffer_get_string(&m, &len);
864 buffer_append(conf, cp, len + 1);
867 if (buffer_get_int(&m)) {
868 if (sensitive_data.server_key != NULL)
869 key_free(sensitive_data.server_key);
870 sensitive_data.server_key = key_new_private(KEY_RSA1);
871 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
872 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
873 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
874 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
875 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
876 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
877 rsa_generate_additional_parameters(
878 sensitive_data.server_key->rsa);
881 #ifndef OPENSSL_PRNG_ONLY
882 rexec_recv_rng_seed(&m);
887 debug3("%s: done", __func__);
891 * Main program for the daemon.
894 main(int ac, char **av)
898 int opt, j, i, on = 1;
899 int sock_in = -1, sock_out = -1, newsock = -1;
903 struct sockaddr_storage from;
904 const char *remote_ip;
908 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
910 int listen_sock, maxfd;
911 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
915 int ret, key_used = 0;
918 #ifdef HAVE_SECUREWARE
919 (void)set_auth_parameters(ac, av);
921 __progname = ssh_get_progname(av[0]);
924 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
927 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
928 for (i = 0; i < ac; i++)
929 saved_argv[i] = xstrdup(av[i]);
930 saved_argv[i] = NULL;
932 #ifndef HAVE_SETPROCTITLE
933 /* Prepare for later setproctitle emulation */
934 compat_init_setproctitle(ac, av);
938 if (geteuid() == 0 && setgroups(0, NULL) == -1)
939 debug("setgroups(): %.200s", strerror(errno));
941 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
944 /* Initialize configuration options to their default values. */
945 initialize_server_options(&options);
947 /* Parse command-line arguments. */
948 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
951 options.address_family = AF_INET;
954 options.address_family = AF_INET6;
957 config_file_name = optarg;
960 if (debug_flag == 0) {
962 options.log_level = SYSLOG_LEVEL_DEBUG1;
963 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
986 options.log_level = SYSLOG_LEVEL_QUIET;
989 options.server_key_bits = (int)strtonum(optarg, 256,
993 options.ports_from_cmdline = 1;
994 if (options.num_ports >= MAX_PORTS) {
995 fprintf(stderr, "too many ports.\n");
998 options.ports[options.num_ports++] = a2port(optarg);
999 if (options.ports[options.num_ports-1] == 0) {
1000 fprintf(stderr, "Bad port number.\n");
1005 if ((options.login_grace_time = convtime(optarg)) == -1) {
1006 fprintf(stderr, "Invalid login grace time.\n");
1011 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1012 fprintf(stderr, "Invalid key regeneration interval.\n");
1017 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1018 fprintf(stderr, "too many host keys.\n");
1021 options.host_key_files[options.num_host_key_files++] = optarg;
1027 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1028 if (utmp_len > MAXHOSTNAMELEN) {
1029 fprintf(stderr, "Invalid utmp length.\n");
1034 line = xstrdup(optarg);
1035 if (process_server_config_line(&options, line,
1036 "command-line", 0) != 0)
1046 if (rexeced_flag || inetd_flag)
1048 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1049 fatal("sshd re-exec requires execution with an absolute path");
1051 closefrom(REEXEC_MIN_FREE_FD);
1053 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1055 SSLeay_add_all_algorithms();
1058 * Force logging to stderr until we have loaded the private host
1059 * key (unless started from inetd)
1061 log_init(__progname,
1062 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1063 SYSLOG_LEVEL_INFO : options.log_level,
1064 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1065 SYSLOG_FACILITY_AUTH : options.log_facility,
1066 log_stderr || !inetd_flag);
1069 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1070 * root's environment
1072 if (getenv("KRB5CCNAME") != NULL)
1073 unsetenv("KRB5CCNAME");
1076 /* Cray can define user privs drop all privs now!
1077 * Not needed on PRIV_SU systems!
1082 sensitive_data.server_key = NULL;
1083 sensitive_data.ssh1_host_key = NULL;
1084 sensitive_data.have_ssh1_key = 0;
1085 sensitive_data.have_ssh2_key = 0;
1087 /* Fetch our configuration */
1090 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1092 load_server_config(config_file_name, &cfg);
1094 parse_server_config(&options,
1095 rexeced_flag ? "rexec" : config_file_name, &cfg);
1102 /* Fill in default values for those options not explicitly set. */
1103 fill_default_server_options(&options);
1105 /* set default channel AF */
1106 channel_set_af(options.address_family);
1108 /* Check that there are no remaining arguments. */
1110 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1114 debug("sshd version %.100s", SSH_RELEASE);
1116 /* load private host keys */
1117 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1119 for (i = 0; i < options.num_host_key_files; i++)
1120 sensitive_data.host_keys[i] = NULL;
1122 for (i = 0; i < options.num_host_key_files; i++) {
1123 key = key_load_private(options.host_key_files[i], "", NULL);
1124 sensitive_data.host_keys[i] = key;
1126 error("Could not load host key: %s",
1127 options.host_key_files[i]);
1128 sensitive_data.host_keys[i] = NULL;
1131 switch (key->type) {
1133 sensitive_data.ssh1_host_key = key;
1134 sensitive_data.have_ssh1_key = 1;
1138 sensitive_data.have_ssh2_key = 1;
1141 debug("private host key: #%d type %d %s", i, key->type,
1144 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1145 logit("Disabling protocol version 1. Could not load host key");
1146 options.protocol &= ~SSH_PROTO_1;
1148 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1149 logit("Disabling protocol version 2. Could not load host key");
1150 options.protocol &= ~SSH_PROTO_2;
1152 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1153 logit("sshd: no hostkeys available -- exiting.");
1157 /* Check certain values for sanity. */
1158 if (options.protocol & SSH_PROTO_1) {
1159 if (options.server_key_bits < 512 ||
1160 options.server_key_bits > 32768) {
1161 fprintf(stderr, "Bad server key size.\n");
1165 * Check that server and host key lengths differ sufficiently. This
1166 * is necessary to make double encryption work with rsaref. Oh, I
1167 * hate software patents. I dont know if this can go? Niels
1169 if (options.server_key_bits >
1170 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1171 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1172 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1173 SSH_KEY_BITS_RESERVED) {
1174 options.server_key_bits =
1175 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1176 SSH_KEY_BITS_RESERVED;
1177 debug("Forcing server key to %d bits to make it differ from host key.",
1178 options.server_key_bits);
1185 if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1186 fatal("Privilege separation user %s does not exist",
1188 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1189 (S_ISDIR(st.st_mode) == 0))
1190 fatal("Missing privilege separation directory: %s",
1191 _PATH_PRIVSEP_CHROOT_DIR);
1194 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1195 (st.st_uid != getuid () ||
1196 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1198 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1200 fatal("%s must be owned by root and not group or "
1201 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1204 /* Configuration looks good, so exit if in test mode. */
1209 * Clear out any supplemental groups we may have inherited. This
1210 * prevents inadvertent creation of files with bad modes (in the
1211 * portable version at least, it's certainly possible for PAM
1212 * to create a file, and we can't control the code in every
1213 * module which might be used).
1215 if (setgroups(0, NULL) < 0)
1216 debug("setgroups() failed: %.200s", strerror(errno));
1219 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1220 for (i = 0; i < rexec_argc; i++) {
1221 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1222 rexec_argv[i] = saved_argv[i];
1224 rexec_argv[rexec_argc] = "-R";
1225 rexec_argv[rexec_argc + 1] = NULL;
1228 /* Initialize the log (it is reinitialized below in case we forked). */
1229 if (debug_flag && (!inetd_flag || rexeced_flag))
1231 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1234 * If not in debugging mode, and not started from inetd, disconnect
1235 * from the controlling terminal, and fork. The original process
1238 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1241 #endif /* TIOCNOTTY */
1242 if (daemon(0, 0) < 0)
1243 fatal("daemon() failed: %.200s", strerror(errno));
1245 /* Disconnect from the controlling tty. */
1247 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1249 (void) ioctl(fd, TIOCNOTTY, NULL);
1252 #endif /* TIOCNOTTY */
1254 /* Reinitialize the log (because of the fork above). */
1255 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1257 /* Initialize the random number generator. */
1260 /* Chdir to the root directory so that the current disk can be
1261 unmounted if desired. */
1264 /* ignore SIGPIPE */
1265 signal(SIGPIPE, SIG_IGN);
1267 /* Start listening for a socket, unless started from inetd. */
1273 close(REEXEC_CONFIG_PASS_FD);
1274 sock_in = sock_out = dup(STDIN_FILENO);
1276 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1277 close(REEXEC_STARTUP_PIPE_FD);
1280 sock_in = dup(STDIN_FILENO);
1281 sock_out = dup(STDOUT_FILENO);
1284 * We intentionally do not close the descriptors 0, 1, and 2
1285 * as our code for setting the descriptors won't work if
1286 * ttyfd happens to be one of those.
1288 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1289 dup2(fd, STDIN_FILENO);
1290 dup2(fd, STDOUT_FILENO);
1291 if (fd > STDOUT_FILENO)
1294 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1295 if ((options.protocol & SSH_PROTO_1) &&
1296 sensitive_data.server_key == NULL)
1297 generate_ephemeral_server_key();
1299 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1300 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1302 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1303 fatal("Too many listen sockets. "
1304 "Enlarge MAX_LISTEN_SOCKS");
1305 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1306 ntop, sizeof(ntop), strport, sizeof(strport),
1307 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1308 error("getnameinfo failed: %.100s",
1309 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1313 /* Create socket for listening. */
1314 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1316 if (listen_sock < 0) {
1317 /* kernel may not support ipv6 */
1318 verbose("socket: %.100s", strerror(errno));
1321 if (set_nonblock(listen_sock) == -1) {
1326 * Set socket options.
1327 * Allow local port reuse in TIME_WAIT.
1329 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1330 &on, sizeof(on)) == -1)
1331 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1333 debug("Bind to port %s on %s.", strport, ntop);
1335 /* Bind the socket to the desired port. */
1336 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1338 error("Bind to port %s on %s failed: %.200s.",
1339 strport, ntop, strerror(errno));
1343 listen_socks[num_listen_socks] = listen_sock;
1346 /* Start listening on the port. */
1347 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1348 fatal("listen on [%s]:%s: %.100s",
1349 ntop, strport, strerror(errno));
1350 logit("Server listening on %s port %s.", ntop, strport);
1352 freeaddrinfo(options.listen_addrs);
1354 if (!num_listen_socks)
1355 fatal("Cannot bind any address.");
1357 if (options.protocol & SSH_PROTO_1)
1358 generate_ephemeral_server_key();
1361 * Arrange to restart on SIGHUP. The handler needs
1364 signal(SIGHUP, sighup_handler);
1366 signal(SIGTERM, sigterm_handler);
1367 signal(SIGQUIT, sigterm_handler);
1369 /* Arrange SIGCHLD to be caught. */
1370 signal(SIGCHLD, main_sigchld_handler);
1372 /* Write out the pid file after the sigterm handler is setup */
1375 * Record our pid in /var/run/sshd.pid to make it
1376 * easier to kill the correct sshd. We don't want to
1377 * do this before the bind above because the bind will
1378 * fail if there already is a daemon, and this will
1379 * overwrite any old pid in the file.
1381 f = fopen(options.pid_file, "wb");
1383 error("Couldn't create pid file \"%s\": %s",
1384 options.pid_file, strerror(errno));
1386 fprintf(f, "%ld\n", (long) getpid());
1391 /* setup fd set for listen */
1394 for (i = 0; i < num_listen_socks; i++)
1395 if (listen_socks[i] > maxfd)
1396 maxfd = listen_socks[i];
1397 /* pipes connected to unauthenticated childs */
1398 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1399 for (i = 0; i < options.max_startups; i++)
1400 startup_pipes[i] = -1;
1403 * Stay listening for connections until the system crashes or
1404 * the daemon is killed with a signal.
1407 if (received_sighup)
1411 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1414 for (i = 0; i < num_listen_socks; i++)
1415 FD_SET(listen_socks[i], fdset);
1416 for (i = 0; i < options.max_startups; i++)
1417 if (startup_pipes[i] != -1)
1418 FD_SET(startup_pipes[i], fdset);
1420 /* Wait in select until there is a connection. */
1421 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1422 if (ret < 0 && errno != EINTR)
1423 error("select: %.100s", strerror(errno));
1424 if (received_sigterm) {
1425 logit("Received signal %d; terminating.",
1426 (int) received_sigterm);
1427 close_listen_socks();
1428 unlink(options.pid_file);
1431 if (key_used && key_do_regen) {
1432 generate_ephemeral_server_key();
1439 for (i = 0; i < options.max_startups; i++)
1440 if (startup_pipes[i] != -1 &&
1441 FD_ISSET(startup_pipes[i], fdset)) {
1443 * the read end of the pipe is ready
1444 * if the child has closed the pipe
1445 * after successful authentication
1446 * or if the child has died
1448 close(startup_pipes[i]);
1449 startup_pipes[i] = -1;
1452 for (i = 0; i < num_listen_socks; i++) {
1453 if (!FD_ISSET(listen_socks[i], fdset))
1455 fromlen = sizeof(from);
1456 newsock = accept(listen_socks[i],
1457 (struct sockaddr *)&from, &fromlen);
1459 if (errno != EINTR && errno != EWOULDBLOCK)
1460 error("accept: %.100s", strerror(errno));
1463 if (unset_nonblock(newsock) == -1) {
1467 if (drop_connection(startups) == 1) {
1468 debug("drop connection #%d", startups);
1472 if (pipe(startup_p) == -1) {
1477 if (rexec_flag && socketpair(AF_UNIX,
1478 SOCK_STREAM, 0, config_s) == -1) {
1479 error("reexec socketpair: %s",
1482 close(startup_p[0]);
1483 close(startup_p[1]);
1487 for (j = 0; j < options.max_startups; j++)
1488 if (startup_pipes[j] == -1) {
1489 startup_pipes[j] = startup_p[0];
1490 if (maxfd < startup_p[0])
1491 maxfd = startup_p[0];
1497 * Got connection. Fork a child to handle it, unless
1498 * we are in debugging mode.
1502 * In debugging mode. Close the listening
1503 * socket, and start processing the
1504 * connection without forking.
1506 debug("Server will not fork when running in debugging mode.");
1507 close_listen_socks();
1510 close(startup_p[0]);
1511 close(startup_p[1]);
1515 send_rexec_state(config_s[0],
1522 * Normal production daemon. Fork, and have
1523 * the child process the connection. The
1524 * parent continues listening.
1526 if ((pid = fork()) == 0) {
1528 * Child. Close the listening and
1529 * max_startup sockets. Start using
1530 * the accepted socket. Reinitialize
1531 * logging (since our pid has changed).
1532 * We break out of the loop to handle
1535 startup_pipe = startup_p[1];
1536 close_startup_pipes();
1537 close_listen_socks();
1540 log_init(__progname,
1542 options.log_facility,
1550 /* Parent. Stay in the loop. */
1552 error("fork: %.100s", strerror(errno));
1554 debug("Forked child %ld.", (long)pid);
1556 close(startup_p[1]);
1559 send_rexec_state(config_s[0], &cfg);
1565 * Mark that the key has been used (it
1566 * was "given" to the child).
1568 if ((options.protocol & SSH_PROTO_1) &&
1570 /* Schedule server key regeneration alarm. */
1571 signal(SIGALRM, key_regeneration_alarm);
1572 alarm(options.key_regeneration_time);
1579 /* child process check (or debug mode) */
1580 if (num_listen_socks < 0)
1585 /* This is the child processing a new connection. */
1586 setproctitle("%s", "[accepted]");
1589 * Create a new session and process group since the 4.4BSD
1590 * setlogin() affects the entire process group. We don't
1591 * want the child to be able to affect the parent.
1593 #if !defined(SSHD_ACQUIRES_CTTY)
1595 * If setsid is called, on some platforms sshd will later acquire a
1596 * controlling terminal which will result in "could not set
1597 * controlling tty" errors.
1599 if (!debug_flag && !inetd_flag && setsid() < 0)
1600 error("setsid: %.100s", strerror(errno));
1606 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1607 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1608 dup2(newsock, STDIN_FILENO);
1609 dup2(STDIN_FILENO, STDOUT_FILENO);
1610 if (startup_pipe == -1)
1611 close(REEXEC_STARTUP_PIPE_FD);
1613 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1615 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1617 if (startup_pipe != -1)
1618 close(startup_pipe);
1620 execv(rexec_argv[0], rexec_argv);
1622 /* Reexec has failed, fall back and continue */
1623 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1624 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1625 log_init(__progname, options.log_level,
1626 options.log_facility, log_stderr);
1629 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1631 close(REEXEC_CONFIG_PASS_FD);
1632 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1633 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1634 dup2(fd, STDIN_FILENO);
1635 dup2(fd, STDOUT_FILENO);
1636 if (fd > STDERR_FILENO)
1639 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1640 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1644 * Disable the key regeneration alarm. We will not regenerate the
1645 * key since we are no longer in a position to give it to anyone. We
1646 * will not restart on SIGHUP since it no longer makes sense.
1649 signal(SIGALRM, SIG_DFL);
1650 signal(SIGHUP, SIG_DFL);
1651 signal(SIGTERM, SIG_DFL);
1652 signal(SIGQUIT, SIG_DFL);
1653 signal(SIGCHLD, SIG_DFL);
1654 signal(SIGINT, SIG_DFL);
1657 * Register our connection. This turns encryption off because we do
1660 packet_set_connection(sock_in, sock_out);
1661 packet_set_server();
1663 /* Set SO_KEEPALIVE if requested. */
1664 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1665 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1666 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1668 if ((remote_port = get_remote_port()) < 0) {
1669 debug("get_remote_port failed");
1674 * We use get_canonical_hostname with usedns = 0 instead of
1675 * get_remote_ipaddr here so IP options will be checked.
1677 (void) get_canonical_hostname(0);
1679 * The rest of the code depends on the fact that
1680 * get_remote_ipaddr() caches the remote ip, even if
1681 * the socket goes away.
1683 remote_ip = get_remote_ipaddr();
1685 #ifdef SSH_AUDIT_EVENTS
1686 audit_connection_from(remote_ip, remote_port);
1689 /* Check whether logins are denied from this host. */
1690 if (packet_connection_is_on_socket()) {
1691 struct request_info req;
1693 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1696 if (!hosts_access(&req)) {
1697 debug("Connection refused by tcp wrapper");
1700 fatal("libwrap refuse returns");
1703 #endif /* LIBWRAP */
1705 /* Log the connection. */
1706 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1709 * We don't want to listen forever unless the other side
1710 * successfully authenticates itself. So we set up an alarm which is
1711 * cleared after successful authentication. A limit of zero
1712 * indicates no limit. Note that we don't set the alarm in debugging
1713 * mode; it is just annoying to have the server exit just when you
1714 * are about to discover the bug.
1716 signal(SIGALRM, grace_alarm_handler);
1718 alarm(options.login_grace_time);
1720 sshd_exchange_identification(sock_in, sock_out);
1722 packet_set_nonblocking();
1724 /* allocate authentication context */
1725 authctxt = xcalloc(1, sizeof(*authctxt));
1727 authctxt->loginmsg = &loginmsg;
1729 /* XXX global for cleanup, access from other modules */
1730 the_authctxt = authctxt;
1732 /* prepare buffer to collect messages to display to user after login */
1733 buffer_init(&loginmsg);
1736 if (privsep_preauth(authctxt) == 1)
1739 /* perform the key exchange */
1740 /* authenticate user and start session */
1743 do_authentication2(authctxt);
1746 do_authentication(authctxt);
1749 * If we use privilege separation, the unprivileged child transfers
1750 * the current keystate and exits
1753 mm_send_keystate(pmonitor);
1759 * Cancel the alarm we set to limit the time taken for
1763 signal(SIGALRM, SIG_DFL);
1764 if (startup_pipe != -1) {
1765 close(startup_pipe);
1769 #ifdef SSH_AUDIT_EVENTS
1770 audit_event(SSH_AUTH_SUCCESS);
1774 * In privilege separation, we fork another child and prepare
1775 * file descriptor passing.
1778 privsep_postauth(authctxt);
1779 /* the monitor process [priv] will not return */
1781 destroy_sensitive_data();
1784 /* Start session. */
1785 do_authenticated(authctxt);
1787 /* The connection has been terminated. */
1788 verbose("Closing connection to %.100s", remote_ip);
1791 if (options.use_pam)
1793 #endif /* USE_PAM */
1795 #ifdef SSH_AUDIT_EVENTS
1796 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1808 * Decrypt session_key_int using our private server key and private host key
1809 * (key with larger modulus first).
1812 ssh1_session_key(BIGNUM *session_key_int)
1816 if (BN_cmp(sensitive_data.server_key->rsa->n,
1817 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1818 /* Server key has bigger modulus. */
1819 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1820 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1821 SSH_KEY_BITS_RESERVED) {
1822 fatal("do_connection: %s: "
1823 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1824 get_remote_ipaddr(),
1825 BN_num_bits(sensitive_data.server_key->rsa->n),
1826 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1827 SSH_KEY_BITS_RESERVED);
1829 if (rsa_private_decrypt(session_key_int, session_key_int,
1830 sensitive_data.server_key->rsa) <= 0)
1832 if (rsa_private_decrypt(session_key_int, session_key_int,
1833 sensitive_data.ssh1_host_key->rsa) <= 0)
1836 /* Host key has bigger modulus (or they are equal). */
1837 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1838 BN_num_bits(sensitive_data.server_key->rsa->n) +
1839 SSH_KEY_BITS_RESERVED) {
1840 fatal("do_connection: %s: "
1841 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1842 get_remote_ipaddr(),
1843 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1844 BN_num_bits(sensitive_data.server_key->rsa->n),
1845 SSH_KEY_BITS_RESERVED);
1847 if (rsa_private_decrypt(session_key_int, session_key_int,
1848 sensitive_data.ssh1_host_key->rsa) < 0)
1850 if (rsa_private_decrypt(session_key_int, session_key_int,
1851 sensitive_data.server_key->rsa) < 0)
1864 BIGNUM *session_key_int;
1865 u_char session_key[SSH_SESSION_KEY_LENGTH];
1867 u_int cipher_type, auth_mask, protocol_flags;
1871 * Generate check bytes that the client must send back in the user
1872 * packet in order for it to be accepted; this is used to defy ip
1873 * spoofing attacks. Note that this only works against somebody
1874 * doing IP spoofing from a remote machine; any machine on the local
1875 * network can still see outgoing packets and catch the random
1876 * cookie. This only affects rhosts authentication, and this is one
1877 * of the reasons why it is inherently insecure.
1879 for (i = 0; i < 8; i++) {
1882 cookie[i] = rnd & 0xff;
1887 * Send our public key. We include in the packet 64 bits of random
1888 * data that must be matched in the reply in order to prevent IP
1891 packet_start(SSH_SMSG_PUBLIC_KEY);
1892 for (i = 0; i < 8; i++)
1893 packet_put_char(cookie[i]);
1895 /* Store our public server RSA key. */
1896 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1897 packet_put_bignum(sensitive_data.server_key->rsa->e);
1898 packet_put_bignum(sensitive_data.server_key->rsa->n);
1900 /* Store our public host RSA key. */
1901 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1902 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1903 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1905 /* Put protocol flags. */
1906 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1908 /* Declare which ciphers we support. */
1909 packet_put_int(cipher_mask_ssh1(0));
1911 /* Declare supported authentication types. */
1913 if (options.rhosts_rsa_authentication)
1914 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1915 if (options.rsa_authentication)
1916 auth_mask |= 1 << SSH_AUTH_RSA;
1917 if (options.challenge_response_authentication == 1)
1918 auth_mask |= 1 << SSH_AUTH_TIS;
1919 if (options.password_authentication)
1920 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1921 packet_put_int(auth_mask);
1923 /* Send the packet and wait for it to be sent. */
1925 packet_write_wait();
1927 debug("Sent %d bit server key and %d bit host key.",
1928 BN_num_bits(sensitive_data.server_key->rsa->n),
1929 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1931 /* Read clients reply (cipher type and session key). */
1932 packet_read_expect(SSH_CMSG_SESSION_KEY);
1934 /* Get cipher type and check whether we accept this. */
1935 cipher_type = packet_get_char();
1937 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1938 packet_disconnect("Warning: client selects unsupported cipher.");
1940 /* Get check bytes from the packet. These must match those we
1941 sent earlier with the public key packet. */
1942 for (i = 0; i < 8; i++)
1943 if (cookie[i] != packet_get_char())
1944 packet_disconnect("IP Spoofing check bytes do not match.");
1946 debug("Encryption type: %.200s", cipher_name(cipher_type));
1948 /* Get the encrypted integer. */
1949 if ((session_key_int = BN_new()) == NULL)
1950 fatal("do_ssh1_kex: BN_new failed");
1951 packet_get_bignum(session_key_int);
1953 protocol_flags = packet_get_int();
1954 packet_set_protocol_flags(protocol_flags);
1957 /* Decrypt session_key_int using host/server keys */
1958 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1961 * Extract session key from the decrypted integer. The key is in the
1962 * least significant 256 bits of the integer; the first byte of the
1963 * key is in the highest bits.
1966 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1967 len = BN_num_bytes(session_key_int);
1968 if (len < 0 || (u_int)len > sizeof(session_key)) {
1969 error("do_connection: bad session key len from %s: "
1970 "session_key_int %d > sizeof(session_key) %lu",
1971 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1974 memset(session_key, 0, sizeof(session_key));
1975 BN_bn2bin(session_key_int,
1976 session_key + sizeof(session_key) - len);
1978 derive_ssh1_session_id(
1979 sensitive_data.ssh1_host_key->rsa->n,
1980 sensitive_data.server_key->rsa->n,
1981 cookie, session_id);
1983 * Xor the first 16 bytes of the session key with the
1986 for (i = 0; i < 16; i++)
1987 session_key[i] ^= session_id[i];
1991 int bytes = BN_num_bytes(session_key_int);
1992 u_char *buf = xmalloc(bytes);
1995 logit("do_connection: generating a fake encryption key");
1996 BN_bn2bin(session_key_int, buf);
1998 MD5_Update(&md, buf, bytes);
1999 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2000 MD5_Final(session_key, &md);
2002 MD5_Update(&md, session_key, 16);
2003 MD5_Update(&md, buf, bytes);
2004 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2005 MD5_Final(session_key + 16, &md);
2006 memset(buf, 0, bytes);
2008 for (i = 0; i < 16; i++)
2009 session_id[i] = session_key[i] ^ session_key[i + 16];
2011 /* Destroy the private and public keys. No longer. */
2012 destroy_sensitive_data();
2015 mm_ssh1_session_id(session_id);
2017 /* Destroy the decrypted integer. It is no longer needed. */
2018 BN_clear_free(session_key_int);
2020 /* Set the session key. From this on all communications will be encrypted. */
2021 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2023 /* Destroy our copy of the session key. It is no longer needed. */
2024 memset(session_key, 0, sizeof(session_key));
2026 debug("Received session key; encryption turned on.");
2028 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2029 packet_start(SSH_SMSG_SUCCESS);
2031 packet_write_wait();
2035 * SSH2 key exchange: diffie-hellman-group1-sha1
2042 if (options.ciphers != NULL) {
2043 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2044 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2046 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2047 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2048 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2049 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2051 if (options.macs != NULL) {
2052 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2053 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2055 if (options.compression == COMP_NONE) {
2056 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2057 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2058 } else if (options.compression == COMP_DELAYED) {
2059 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2060 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2063 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2065 /* start key exchange */
2066 kex = kex_setup(myproposal);
2067 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2068 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2069 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2070 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2072 kex->client_version_string=client_version_string;
2073 kex->server_version_string=server_version_string;
2074 kex->load_host_key=&get_hostkey_by_type;
2075 kex->host_key_index=&get_hostkey_index;
2079 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2081 session_id2 = kex->session_id;
2082 session_id2_len = kex->session_id_len;
2085 /* send 1st encrypted/maced/compressed message */
2086 packet_start(SSH2_MSG_IGNORE);
2087 packet_put_cstring("markus");
2089 packet_write_wait();
2094 /* server specific fatal cleanup */
2099 do_cleanup(the_authctxt);
2100 #ifdef SSH_AUDIT_EVENTS
2101 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2102 if (!use_privsep || mm_is_monitor())
2103 audit_event(SSH_CONNECTION_ABANDON);