1 /* $OpenBSD: sshd.c,v 1.340 2006/07/25 02:59:21 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>
53 #ifdef HAVE_SYS_TIME_H
54 # include <sys/time.h>
69 #include <openssl/dh.h>
70 #include <openssl/bn.h>
71 #include <openssl/md5.h>
72 #include <openssl/rand.h>
73 #ifdef HAVE_SECUREWARE
74 #include <sys/security.h>
95 #include "myproposal.h"
97 #include "pathnames.h"
103 #include "dispatch.h"
104 #include "channels.h"
106 #include "monitor_mm.h"
108 #include "monitor_wrap.h"
109 #include "monitor_fdpass.h"
115 int allow_severity = LOG_INFO;
116 int deny_severity = LOG_WARNING;
124 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
125 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
126 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
127 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
129 extern char *__progname;
131 /* Server configuration options. */
132 ServerOptions options;
134 /* Name of the server configuration file. */
135 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
138 * Debug mode flag. This can be set on the command line. If debug
139 * mode is enabled, extra debugging output will be sent to the system
140 * log, the daemon will not go to background, and will exit after processing
141 * the first connection.
145 /* Flag indicating that the daemon should only test the configuration and keys. */
148 /* Flag indicating that the daemon is being started from inetd. */
151 /* Flag indicating that sshd should not detach and become a daemon. */
152 int no_daemon_flag = 0;
154 /* debug goes to stderr unless inetd_flag is set */
157 /* Saved arguments to main(). */
162 int rexeced_flag = 0;
168 * The sockets that the server is listening; this is used in the SIGHUP
171 #define MAX_LISTEN_SOCKS 16
172 int listen_socks[MAX_LISTEN_SOCKS];
173 int num_listen_socks = 0;
176 * the client's version string, passed by sshd2 in compat mode. if != NULL,
177 * sshd will skip the version-number exchange
179 char *client_version_string = NULL;
180 char *server_version_string = NULL;
182 /* for rekeying XXX fixme */
186 * Any really sensitive data in the application is contained in this
187 * structure. The idea is that this structure could be locked into memory so
188 * that the pages do not get written into swap. However, there are some
189 * problems. The private key contains BIGNUMs, and we do not (in principle)
190 * have access to the internals of them, and locking just the structure is
191 * not very useful. Currently, memory locking is not implemented.
194 Key *server_key; /* ephemeral server key */
195 Key *ssh1_host_key; /* ssh1 host key */
196 Key **host_keys; /* all private host keys */
199 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
203 * Flag indicating whether the RSA server key needs to be regenerated.
204 * Is set in the SIGALRM handler and cleared when the key is regenerated.
206 static volatile sig_atomic_t key_do_regen = 0;
208 /* This is set to true when a signal is received. */
209 static volatile sig_atomic_t received_sighup = 0;
210 static volatile sig_atomic_t received_sigterm = 0;
212 /* session identifier, used by RSA-auth */
213 u_char session_id[16];
216 u_char *session_id2 = NULL;
217 u_int session_id2_len = 0;
219 /* record remote hostname or ip */
220 u_int utmp_len = MAXHOSTNAMELEN;
222 /* options.max_startup sized array of fd ints */
223 int *startup_pipes = NULL;
224 int startup_pipe; /* in child */
226 /* variables used for privilege separation */
227 int use_privsep = -1;
228 struct monitor *pmonitor = NULL;
230 /* global authentication context */
231 Authctxt *the_authctxt = NULL;
233 /* sshd_config buffer */
236 /* message to be displayed after login */
239 /* Prototypes for various functions defined later in this file. */
240 void destroy_sensitive_data(void);
241 void demote_sensitive_data(void);
243 static void do_ssh1_kex(void);
244 static void do_ssh2_kex(void);
247 * Close all listening sockets
250 close_listen_socks(void)
254 for (i = 0; i < num_listen_socks; i++)
255 close(listen_socks[i]);
256 num_listen_socks = -1;
260 close_startup_pipes(void)
265 for (i = 0; i < options.max_startups; i++)
266 if (startup_pipes[i] != -1)
267 close(startup_pipes[i]);
271 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
272 * the effect is to reread the configuration file (and to regenerate
278 sighup_handler(int sig)
280 int save_errno = errno;
283 signal(SIGHUP, sighup_handler);
288 * Called from the main program after receiving SIGHUP.
289 * Restarts the server.
294 logit("Received SIGHUP; restarting.");
295 close_listen_socks();
296 close_startup_pipes();
297 execv(saved_argv[0], saved_argv);
298 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
304 * Generic signal handler for terminating signals in the master daemon.
308 sigterm_handler(int sig)
310 received_sigterm = sig;
314 * SIGCHLD handler. This is called whenever a child dies. This will then
315 * reap any zombies left by exited children.
319 main_sigchld_handler(int sig)
321 int save_errno = errno;
325 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
326 (pid < 0 && errno == EINTR))
329 signal(SIGCHLD, main_sigchld_handler);
334 * Signal handler for the alarm after the login grace period has expired.
338 grace_alarm_handler(int sig)
340 /* XXX no idea how fix this signal handler */
342 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
343 kill(pmonitor->m_pid, SIGALRM);
345 /* Log error and exit. */
346 fatal("Timeout before authentication for %s", get_remote_ipaddr());
350 * Signal handler for the key regeneration alarm. Note that this
351 * alarm only occurs in the daemon waiting for connections, and it does not
352 * do anything with the private key or random state before forking.
353 * Thus there should be no concurrency control/asynchronous execution
357 generate_ephemeral_server_key(void)
362 verbose("Generating %s%d bit RSA key.",
363 sensitive_data.server_key ? "new " : "", options.server_key_bits);
364 if (sensitive_data.server_key != NULL)
365 key_free(sensitive_data.server_key);
366 sensitive_data.server_key = key_generate(KEY_RSA1,
367 options.server_key_bits);
368 verbose("RSA key generation complete.");
370 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
373 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
381 key_regeneration_alarm(int sig)
383 int save_errno = errno;
385 signal(SIGALRM, SIG_DFL);
391 sshd_exchange_identification(int sock_in, int sock_out)
395 int remote_major, remote_minor;
398 char buf[256]; /* Must not be larger than remote_version. */
399 char remote_version[256]; /* Must be at least as big as buf. */
401 if ((options.protocol & SSH_PROTO_1) &&
402 (options.protocol & SSH_PROTO_2)) {
403 major = PROTOCOL_MAJOR_1;
405 } else if (options.protocol & SSH_PROTO_2) {
406 major = PROTOCOL_MAJOR_2;
407 minor = PROTOCOL_MINOR_2;
409 major = PROTOCOL_MAJOR_1;
410 minor = PROTOCOL_MINOR_1;
412 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
413 server_version_string = xstrdup(buf);
415 /* Send our protocol version identification. */
416 if (atomicio(vwrite, sock_out, server_version_string,
417 strlen(server_version_string))
418 != strlen(server_version_string)) {
419 logit("Could not write ident string to %s", get_remote_ipaddr());
423 /* Read other sides version identification. */
424 memset(buf, 0, sizeof(buf));
425 for (i = 0; i < sizeof(buf) - 1; i++) {
426 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
427 logit("Did not receive identification string from %s",
428 get_remote_ipaddr());
431 if (buf[i] == '\r') {
433 /* Kludge for F-Secure Macintosh < 1.0.2 */
435 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
439 if (buf[i] == '\n') {
444 buf[sizeof(buf) - 1] = 0;
445 client_version_string = xstrdup(buf);
448 * Check that the versions match. In future this might accept
449 * several versions and set appropriate flags to handle them.
451 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
452 &remote_major, &remote_minor, remote_version) != 3) {
453 s = "Protocol mismatch.\n";
454 (void) atomicio(vwrite, sock_out, s, strlen(s));
457 logit("Bad protocol version identification '%.100s' from %s",
458 client_version_string, get_remote_ipaddr());
461 debug("Client protocol version %d.%d; client software version %.100s",
462 remote_major, remote_minor, remote_version);
464 compat_datafellows(remote_version);
466 if (datafellows & SSH_BUG_PROBE) {
467 logit("probed from %s with %s. Don't panic.",
468 get_remote_ipaddr(), client_version_string);
472 if (datafellows & SSH_BUG_SCANNER) {
473 logit("scanned from %s with %s. Don't panic.",
474 get_remote_ipaddr(), client_version_string);
479 switch (remote_major) {
481 if (remote_minor == 99) {
482 if (options.protocol & SSH_PROTO_2)
488 if (!(options.protocol & SSH_PROTO_1)) {
492 if (remote_minor < 3) {
493 packet_disconnect("Your ssh version is too old and "
494 "is no longer supported. Please install a newer version.");
495 } else if (remote_minor == 3) {
496 /* note that this disables agent-forwarding */
501 if (options.protocol & SSH_PROTO_2) {
510 chop(server_version_string);
511 debug("Local version string %.200s", server_version_string);
514 s = "Protocol major versions differ.\n";
515 (void) atomicio(vwrite, sock_out, s, strlen(s));
518 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
520 server_version_string, client_version_string);
525 /* Destroy the host and server keys. They will no longer be needed. */
527 destroy_sensitive_data(void)
531 if (sensitive_data.server_key) {
532 key_free(sensitive_data.server_key);
533 sensitive_data.server_key = NULL;
535 for (i = 0; i < options.num_host_key_files; i++) {
536 if (sensitive_data.host_keys[i]) {
537 key_free(sensitive_data.host_keys[i]);
538 sensitive_data.host_keys[i] = NULL;
541 sensitive_data.ssh1_host_key = NULL;
542 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
545 /* Demote private to public keys for network child */
547 demote_sensitive_data(void)
552 if (sensitive_data.server_key) {
553 tmp = key_demote(sensitive_data.server_key);
554 key_free(sensitive_data.server_key);
555 sensitive_data.server_key = tmp;
558 for (i = 0; i < options.num_host_key_files; i++) {
559 if (sensitive_data.host_keys[i]) {
560 tmp = key_demote(sensitive_data.host_keys[i]);
561 key_free(sensitive_data.host_keys[i]);
562 sensitive_data.host_keys[i] = tmp;
563 if (tmp->type == KEY_RSA1)
564 sensitive_data.ssh1_host_key = tmp;
568 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
572 privsep_preauth_child(void)
579 /* Enable challenge-response authentication for privilege separation */
580 privsep_challenge_enable();
582 for (i = 0; i < 256; i++)
583 rnd[i] = arc4random();
584 RAND_seed(rnd, sizeof(rnd));
586 /* Demote the private keys to public keys. */
587 demote_sensitive_data();
589 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
590 fatal("Privilege separation user %s does not exist",
592 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
595 /* Change our root directory */
596 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
597 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
599 if (chdir("/") == -1)
600 fatal("chdir(\"/\"): %s", strerror(errno));
602 /* Drop our privileges */
603 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
606 /* XXX not ready, too heavy after chroot */
607 do_setusercontext(pw);
609 gidset[0] = pw->pw_gid;
610 if (setgroups(1, gidset) < 0)
611 fatal("setgroups: %.100s", strerror(errno));
612 permanently_set_uid(pw);
617 privsep_preauth(Authctxt *authctxt)
622 /* Set up unprivileged child process to deal with network data */
623 pmonitor = monitor_init();
624 /* Store a pointer to the kex for later rekeying */
625 pmonitor->m_pkex = &xxx_kex;
629 fatal("fork of unprivileged child failed");
630 } else if (pid != 0) {
631 debug2("Network child is on pid %ld", (long)pid);
633 close(pmonitor->m_recvfd);
634 pmonitor->m_pid = pid;
635 monitor_child_preauth(authctxt, pmonitor);
636 close(pmonitor->m_sendfd);
639 monitor_sync(pmonitor);
641 /* Wait for the child's exit status */
642 while (waitpid(pid, &status, 0) < 0)
649 close(pmonitor->m_sendfd);
651 /* Demote the child */
652 if (getuid() == 0 || geteuid() == 0)
653 privsep_preauth_child();
654 setproctitle("%s", "[net]");
660 privsep_postauth(Authctxt *authctxt)
662 #ifdef DISABLE_FD_PASSING
665 if (authctxt->pw->pw_uid == 0 || options.use_login) {
667 /* File descriptor passing is broken or root login */
672 /* New socket pair */
673 monitor_reinit(pmonitor);
675 pmonitor->m_pid = fork();
676 if (pmonitor->m_pid == -1)
677 fatal("fork of unprivileged child failed");
678 else if (pmonitor->m_pid != 0) {
679 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
680 close(pmonitor->m_recvfd);
681 buffer_clear(&loginmsg);
682 monitor_child_postauth(pmonitor);
688 close(pmonitor->m_sendfd);
690 /* Demote the private keys to public keys. */
691 demote_sensitive_data();
693 /* Drop privileges */
694 do_setusercontext(authctxt->pw);
697 /* It is safe now to apply the key state */
698 monitor_apply_keystate(pmonitor);
701 * Tell the packet layer that authentication was successful, since
702 * this information is not part of the key state.
704 packet_set_authenticated();
708 list_hostkey_types(void)
716 for (i = 0; i < options.num_host_key_files; i++) {
717 Key *key = sensitive_data.host_keys[i];
723 if (buffer_len(&b) > 0)
724 buffer_append(&b, ",", 1);
725 p = key_ssh_name(key);
726 buffer_append(&b, p, strlen(p));
730 buffer_append(&b, "\0", 1);
731 ret = xstrdup(buffer_ptr(&b));
733 debug("list_hostkey_types: %s", ret);
738 get_hostkey_by_type(int type)
742 for (i = 0; i < options.num_host_key_files; i++) {
743 Key *key = sensitive_data.host_keys[i];
744 if (key != NULL && key->type == type)
751 get_hostkey_by_index(int ind)
753 if (ind < 0 || ind >= options.num_host_key_files)
755 return (sensitive_data.host_keys[ind]);
759 get_hostkey_index(Key *key)
763 for (i = 0; i < options.num_host_key_files; i++) {
764 if (key == sensitive_data.host_keys[i])
771 * returns 1 if connection should be dropped, 0 otherwise.
772 * dropping starts at connection #max_startups_begin with a probability
773 * of (max_startups_rate/100). the probability increases linearly until
774 * all connections are dropped for startups > max_startups
777 drop_connection(int startups)
781 if (startups < options.max_startups_begin)
783 if (startups >= options.max_startups)
785 if (options.max_startups_rate == 100)
788 p = 100 - options.max_startups_rate;
789 p *= startups - options.max_startups_begin;
790 p /= options.max_startups - options.max_startups_begin;
791 p += options.max_startups_rate;
792 r = arc4random() % 100;
794 debug("drop_connection: p %d, r %d", p, r);
795 return (r < p) ? 1 : 0;
801 fprintf(stderr, "%s, %s\n",
802 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
804 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
805 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
811 send_rexec_state(int fd, Buffer *conf)
815 debug3("%s: entering fd = %d config len %d", __func__, fd,
819 * Protocol from reexec master to child:
820 * string configuration
821 * u_int ephemeral_key_follows
822 * bignum e (only if ephemeral_key_follows == 1)
828 * string rngseed (only if OpenSSL is not self-seeded)
831 buffer_put_cstring(&m, buffer_ptr(conf));
833 if (sensitive_data.server_key != NULL &&
834 sensitive_data.server_key->type == KEY_RSA1) {
835 buffer_put_int(&m, 1);
836 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
837 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
838 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
839 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
840 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
841 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
843 buffer_put_int(&m, 0);
845 #ifndef OPENSSL_PRNG_ONLY
846 rexec_send_rng_seed(&m);
849 if (ssh_msg_send(fd, 0, &m) == -1)
850 fatal("%s: ssh_msg_send failed", __func__);
854 debug3("%s: done", __func__);
858 recv_rexec_state(int fd, Buffer *conf)
864 debug3("%s: entering fd = %d", __func__, fd);
868 if (ssh_msg_recv(fd, &m) == -1)
869 fatal("%s: ssh_msg_recv failed", __func__);
870 if (buffer_get_char(&m) != 0)
871 fatal("%s: rexec version mismatch", __func__);
873 cp = buffer_get_string(&m, &len);
875 buffer_append(conf, cp, len + 1);
878 if (buffer_get_int(&m)) {
879 if (sensitive_data.server_key != NULL)
880 key_free(sensitive_data.server_key);
881 sensitive_data.server_key = key_new_private(KEY_RSA1);
882 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
883 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
884 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
885 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
886 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
887 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
888 rsa_generate_additional_parameters(
889 sensitive_data.server_key->rsa);
892 #ifndef OPENSSL_PRNG_ONLY
893 rexec_recv_rng_seed(&m);
898 debug3("%s: done", __func__);
902 * Main program for the daemon.
905 main(int ac, char **av)
909 int opt, j, i, on = 1;
910 int sock_in = -1, sock_out = -1, newsock = -1;
914 struct sockaddr_storage from;
915 const char *remote_ip;
919 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
921 int listen_sock, maxfd;
922 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
926 int ret, key_used = 0;
928 #ifdef HAVE_SECUREWARE
929 (void)set_auth_parameters(ac, av);
931 __progname = ssh_get_progname(av[0]);
934 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
937 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
938 for (i = 0; i < ac; i++)
939 saved_argv[i] = xstrdup(av[i]);
940 saved_argv[i] = NULL;
942 #ifndef HAVE_SETPROCTITLE
943 /* Prepare for later setproctitle emulation */
944 compat_init_setproctitle(ac, av);
948 if (geteuid() == 0 && setgroups(0, NULL) == -1)
949 debug("setgroups(): %.200s", strerror(errno));
951 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
954 /* Initialize configuration options to their default values. */
955 initialize_server_options(&options);
957 /* Parse command-line arguments. */
958 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
961 options.address_family = AF_INET;
964 options.address_family = AF_INET6;
967 config_file_name = optarg;
970 if (debug_flag == 0) {
972 options.log_level = SYSLOG_LEVEL_DEBUG1;
973 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
996 options.log_level = SYSLOG_LEVEL_QUIET;
999 options.server_key_bits = (int)strtonum(optarg, 256,
1003 options.ports_from_cmdline = 1;
1004 if (options.num_ports >= MAX_PORTS) {
1005 fprintf(stderr, "too many ports.\n");
1008 options.ports[options.num_ports++] = a2port(optarg);
1009 if (options.ports[options.num_ports-1] == 0) {
1010 fprintf(stderr, "Bad port number.\n");
1015 if ((options.login_grace_time = convtime(optarg)) == -1) {
1016 fprintf(stderr, "Invalid login grace time.\n");
1021 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1022 fprintf(stderr, "Invalid key regeneration interval.\n");
1027 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1028 fprintf(stderr, "too many host keys.\n");
1031 options.host_key_files[options.num_host_key_files++] = optarg;
1037 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1038 if (utmp_len > MAXHOSTNAMELEN) {
1039 fprintf(stderr, "Invalid utmp length.\n");
1044 line = xstrdup(optarg);
1045 if (process_server_config_line(&options, line,
1046 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1056 if (rexeced_flag || inetd_flag)
1058 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1059 fatal("sshd re-exec requires execution with an absolute path");
1061 closefrom(REEXEC_MIN_FREE_FD);
1063 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1065 SSLeay_add_all_algorithms();
1068 * Force logging to stderr until we have loaded the private host
1069 * key (unless started from inetd)
1071 log_init(__progname,
1072 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1073 SYSLOG_LEVEL_INFO : options.log_level,
1074 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1075 SYSLOG_FACILITY_AUTH : options.log_facility,
1076 log_stderr || !inetd_flag);
1079 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1080 * root's environment
1082 if (getenv("KRB5CCNAME") != NULL)
1083 unsetenv("KRB5CCNAME");
1086 /* Cray can define user privs drop all privs now!
1087 * Not needed on PRIV_SU systems!
1092 sensitive_data.server_key = NULL;
1093 sensitive_data.ssh1_host_key = NULL;
1094 sensitive_data.have_ssh1_key = 0;
1095 sensitive_data.have_ssh2_key = 0;
1097 /* Fetch our configuration */
1100 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1102 load_server_config(config_file_name, &cfg);
1104 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1105 &cfg, NULL, NULL, NULL);
1109 /* Fill in default values for those options not explicitly set. */
1110 fill_default_server_options(&options);
1112 /* set default channel AF */
1113 channel_set_af(options.address_family);
1115 /* Check that there are no remaining arguments. */
1117 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1121 debug("sshd version %.100s", SSH_RELEASE);
1123 /* load private host keys */
1124 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1126 for (i = 0; i < options.num_host_key_files; i++)
1127 sensitive_data.host_keys[i] = NULL;
1129 for (i = 0; i < options.num_host_key_files; i++) {
1130 key = key_load_private(options.host_key_files[i], "", NULL);
1131 sensitive_data.host_keys[i] = key;
1133 error("Could not load host key: %s",
1134 options.host_key_files[i]);
1135 sensitive_data.host_keys[i] = NULL;
1138 switch (key->type) {
1140 sensitive_data.ssh1_host_key = key;
1141 sensitive_data.have_ssh1_key = 1;
1145 sensitive_data.have_ssh2_key = 1;
1148 debug("private host key: #%d type %d %s", i, key->type,
1151 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1152 logit("Disabling protocol version 1. Could not load host key");
1153 options.protocol &= ~SSH_PROTO_1;
1155 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1156 logit("Disabling protocol version 2. Could not load host key");
1157 options.protocol &= ~SSH_PROTO_2;
1159 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1160 logit("sshd: no hostkeys available -- exiting.");
1164 /* Check certain values for sanity. */
1165 if (options.protocol & SSH_PROTO_1) {
1166 if (options.server_key_bits < 512 ||
1167 options.server_key_bits > 32768) {
1168 fprintf(stderr, "Bad server key size.\n");
1172 * Check that server and host key lengths differ sufficiently. This
1173 * is necessary to make double encryption work with rsaref. Oh, I
1174 * hate software patents. I dont know if this can go? Niels
1176 if (options.server_key_bits >
1177 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1178 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1179 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1180 SSH_KEY_BITS_RESERVED) {
1181 options.server_key_bits =
1182 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1183 SSH_KEY_BITS_RESERVED;
1184 debug("Forcing server key to %d bits to make it differ from host key.",
1185 options.server_key_bits);
1192 if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1193 fatal("Privilege separation user %s does not exist",
1195 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1196 (S_ISDIR(st.st_mode) == 0))
1197 fatal("Missing privilege separation directory: %s",
1198 _PATH_PRIVSEP_CHROOT_DIR);
1201 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1202 (st.st_uid != getuid () ||
1203 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1205 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1207 fatal("%s must be owned by root and not group or "
1208 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1211 /* Configuration looks good, so exit if in test mode. */
1216 * Clear out any supplemental groups we may have inherited. This
1217 * prevents inadvertent creation of files with bad modes (in the
1218 * portable version at least, it's certainly possible for PAM
1219 * to create a file, and we can't control the code in every
1220 * module which might be used).
1222 if (setgroups(0, NULL) < 0)
1223 debug("setgroups() failed: %.200s", strerror(errno));
1226 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1227 for (i = 0; i < rexec_argc; i++) {
1228 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1229 rexec_argv[i] = saved_argv[i];
1231 rexec_argv[rexec_argc] = "-R";
1232 rexec_argv[rexec_argc + 1] = NULL;
1235 /* Initialize the log (it is reinitialized below in case we forked). */
1236 if (debug_flag && (!inetd_flag || rexeced_flag))
1238 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1241 * If not in debugging mode, and not started from inetd, disconnect
1242 * from the controlling terminal, and fork. The original process
1245 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1248 #endif /* TIOCNOTTY */
1249 if (daemon(0, 0) < 0)
1250 fatal("daemon() failed: %.200s", strerror(errno));
1252 /* Disconnect from the controlling tty. */
1254 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1256 (void) ioctl(fd, TIOCNOTTY, NULL);
1259 #endif /* TIOCNOTTY */
1261 /* Reinitialize the log (because of the fork above). */
1262 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1264 /* Initialize the random number generator. */
1267 /* Chdir to the root directory so that the current disk can be
1268 unmounted if desired. */
1271 /* ignore SIGPIPE */
1272 signal(SIGPIPE, SIG_IGN);
1274 /* Start listening for a socket, unless started from inetd. */
1280 close(REEXEC_CONFIG_PASS_FD);
1281 sock_in = sock_out = dup(STDIN_FILENO);
1283 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1284 close(REEXEC_STARTUP_PIPE_FD);
1287 sock_in = dup(STDIN_FILENO);
1288 sock_out = dup(STDOUT_FILENO);
1291 * We intentionally do not close the descriptors 0, 1, and 2
1292 * as our code for setting the descriptors won't work if
1293 * ttyfd happens to be one of those.
1295 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1296 dup2(fd, STDIN_FILENO);
1297 dup2(fd, STDOUT_FILENO);
1298 if (fd > STDOUT_FILENO)
1301 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1302 if ((options.protocol & SSH_PROTO_1) &&
1303 sensitive_data.server_key == NULL)
1304 generate_ephemeral_server_key();
1306 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1307 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1309 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1310 fatal("Too many listen sockets. "
1311 "Enlarge MAX_LISTEN_SOCKS");
1312 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1313 ntop, sizeof(ntop), strport, sizeof(strport),
1314 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1315 error("getnameinfo failed: %.100s",
1316 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1320 /* Create socket for listening. */
1321 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1323 if (listen_sock < 0) {
1324 /* kernel may not support ipv6 */
1325 verbose("socket: %.100s", strerror(errno));
1328 if (set_nonblock(listen_sock) == -1) {
1333 * Set socket options.
1334 * Allow local port reuse in TIME_WAIT.
1336 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1337 &on, sizeof(on)) == -1)
1338 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1340 debug("Bind to port %s on %s.", strport, ntop);
1342 /* Bind the socket to the desired port. */
1343 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1345 error("Bind to port %s on %s failed: %.200s.",
1346 strport, ntop, strerror(errno));
1350 listen_socks[num_listen_socks] = listen_sock;
1353 /* Start listening on the port. */
1354 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1355 fatal("listen on [%s]:%s: %.100s",
1356 ntop, strport, strerror(errno));
1357 logit("Server listening on %s port %s.", ntop, strport);
1359 freeaddrinfo(options.listen_addrs);
1361 if (!num_listen_socks)
1362 fatal("Cannot bind any address.");
1364 if (options.protocol & SSH_PROTO_1)
1365 generate_ephemeral_server_key();
1368 * Arrange to restart on SIGHUP. The handler needs
1371 signal(SIGHUP, sighup_handler);
1373 signal(SIGTERM, sigterm_handler);
1374 signal(SIGQUIT, sigterm_handler);
1376 /* Arrange SIGCHLD to be caught. */
1377 signal(SIGCHLD, main_sigchld_handler);
1379 /* Write out the pid file after the sigterm handler is setup */
1382 * Record our pid in /var/run/sshd.pid to make it
1383 * easier to kill the correct sshd. We don't want to
1384 * do this before the bind above because the bind will
1385 * fail if there already is a daemon, and this will
1386 * overwrite any old pid in the file.
1388 f = fopen(options.pid_file, "wb");
1390 error("Couldn't create pid file \"%s\": %s",
1391 options.pid_file, strerror(errno));
1393 fprintf(f, "%ld\n", (long) getpid());
1398 /* setup fd set for listen */
1401 for (i = 0; i < num_listen_socks; i++)
1402 if (listen_socks[i] > maxfd)
1403 maxfd = listen_socks[i];
1404 /* pipes connected to unauthenticated childs */
1405 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1406 for (i = 0; i < options.max_startups; i++)
1407 startup_pipes[i] = -1;
1410 * Stay listening for connections until the system crashes or
1411 * the daemon is killed with a signal.
1414 if (received_sighup)
1418 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1421 for (i = 0; i < num_listen_socks; i++)
1422 FD_SET(listen_socks[i], fdset);
1423 for (i = 0; i < options.max_startups; i++)
1424 if (startup_pipes[i] != -1)
1425 FD_SET(startup_pipes[i], fdset);
1427 /* Wait in select until there is a connection. */
1428 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1429 if (ret < 0 && errno != EINTR)
1430 error("select: %.100s", strerror(errno));
1431 if (received_sigterm) {
1432 logit("Received signal %d; terminating.",
1433 (int) received_sigterm);
1434 close_listen_socks();
1435 unlink(options.pid_file);
1438 if (key_used && key_do_regen) {
1439 generate_ephemeral_server_key();
1446 for (i = 0; i < options.max_startups; i++)
1447 if (startup_pipes[i] != -1 &&
1448 FD_ISSET(startup_pipes[i], fdset)) {
1450 * the read end of the pipe is ready
1451 * if the child has closed the pipe
1452 * after successful authentication
1453 * or if the child has died
1455 close(startup_pipes[i]);
1456 startup_pipes[i] = -1;
1459 for (i = 0; i < num_listen_socks; i++) {
1460 if (!FD_ISSET(listen_socks[i], fdset))
1462 fromlen = sizeof(from);
1463 newsock = accept(listen_socks[i],
1464 (struct sockaddr *)&from, &fromlen);
1466 if (errno != EINTR && errno != EWOULDBLOCK)
1467 error("accept: %.100s", strerror(errno));
1470 if (unset_nonblock(newsock) == -1) {
1474 if (drop_connection(startups) == 1) {
1475 debug("drop connection #%d", startups);
1479 if (pipe(startup_p) == -1) {
1484 if (rexec_flag && socketpair(AF_UNIX,
1485 SOCK_STREAM, 0, config_s) == -1) {
1486 error("reexec socketpair: %s",
1489 close(startup_p[0]);
1490 close(startup_p[1]);
1494 for (j = 0; j < options.max_startups; j++)
1495 if (startup_pipes[j] == -1) {
1496 startup_pipes[j] = startup_p[0];
1497 if (maxfd < startup_p[0])
1498 maxfd = startup_p[0];
1504 * Got connection. Fork a child to handle it, unless
1505 * we are in debugging mode.
1509 * In debugging mode. Close the listening
1510 * socket, and start processing the
1511 * connection without forking.
1513 debug("Server will not fork when running in debugging mode.");
1514 close_listen_socks();
1517 close(startup_p[0]);
1518 close(startup_p[1]);
1522 send_rexec_state(config_s[0],
1529 * Normal production daemon. Fork, and have
1530 * the child process the connection. The
1531 * parent continues listening.
1533 if ((pid = fork()) == 0) {
1535 * Child. Close the listening and
1536 * max_startup sockets. Start using
1537 * the accepted socket. Reinitialize
1538 * logging (since our pid has changed).
1539 * We break out of the loop to handle
1542 startup_pipe = startup_p[1];
1543 close_startup_pipes();
1544 close_listen_socks();
1547 log_init(__progname,
1549 options.log_facility,
1557 /* Parent. Stay in the loop. */
1559 error("fork: %.100s", strerror(errno));
1561 debug("Forked child %ld.", (long)pid);
1563 close(startup_p[1]);
1566 send_rexec_state(config_s[0], &cfg);
1572 * Mark that the key has been used (it
1573 * was "given" to the child).
1575 if ((options.protocol & SSH_PROTO_1) &&
1577 /* Schedule server key regeneration alarm. */
1578 signal(SIGALRM, key_regeneration_alarm);
1579 alarm(options.key_regeneration_time);
1586 /* child process check (or debug mode) */
1587 if (num_listen_socks < 0)
1592 /* This is the child processing a new connection. */
1593 setproctitle("%s", "[accepted]");
1596 * Create a new session and process group since the 4.4BSD
1597 * setlogin() affects the entire process group. We don't
1598 * want the child to be able to affect the parent.
1600 #if !defined(SSHD_ACQUIRES_CTTY)
1602 * If setsid is called, on some platforms sshd will later acquire a
1603 * controlling terminal which will result in "could not set
1604 * controlling tty" errors.
1606 if (!debug_flag && !inetd_flag && setsid() < 0)
1607 error("setsid: %.100s", strerror(errno));
1613 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1614 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1615 dup2(newsock, STDIN_FILENO);
1616 dup2(STDIN_FILENO, STDOUT_FILENO);
1617 if (startup_pipe == -1)
1618 close(REEXEC_STARTUP_PIPE_FD);
1620 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1622 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1624 if (startup_pipe != -1)
1625 close(startup_pipe);
1627 execv(rexec_argv[0], rexec_argv);
1629 /* Reexec has failed, fall back and continue */
1630 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1631 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1632 log_init(__progname, options.log_level,
1633 options.log_facility, log_stderr);
1636 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1638 close(REEXEC_CONFIG_PASS_FD);
1639 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1640 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1641 dup2(fd, STDIN_FILENO);
1642 dup2(fd, STDOUT_FILENO);
1643 if (fd > STDERR_FILENO)
1646 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1647 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1651 * Disable the key regeneration alarm. We will not regenerate the
1652 * key since we are no longer in a position to give it to anyone. We
1653 * will not restart on SIGHUP since it no longer makes sense.
1656 signal(SIGALRM, SIG_DFL);
1657 signal(SIGHUP, SIG_DFL);
1658 signal(SIGTERM, SIG_DFL);
1659 signal(SIGQUIT, SIG_DFL);
1660 signal(SIGCHLD, SIG_DFL);
1661 signal(SIGINT, SIG_DFL);
1664 * Register our connection. This turns encryption off because we do
1667 packet_set_connection(sock_in, sock_out);
1668 packet_set_server();
1670 /* Set SO_KEEPALIVE if requested. */
1671 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1672 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1673 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1675 if ((remote_port = get_remote_port()) < 0) {
1676 debug("get_remote_port failed");
1681 * We use get_canonical_hostname with usedns = 0 instead of
1682 * get_remote_ipaddr here so IP options will be checked.
1684 (void) get_canonical_hostname(0);
1686 * The rest of the code depends on the fact that
1687 * get_remote_ipaddr() caches the remote ip, even if
1688 * the socket goes away.
1690 remote_ip = get_remote_ipaddr();
1692 #ifdef SSH_AUDIT_EVENTS
1693 audit_connection_from(remote_ip, remote_port);
1696 /* Check whether logins are denied from this host. */
1697 if (packet_connection_is_on_socket()) {
1698 struct request_info req;
1700 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1703 if (!hosts_access(&req)) {
1704 debug("Connection refused by tcp wrapper");
1707 fatal("libwrap refuse returns");
1710 #endif /* LIBWRAP */
1712 /* Log the connection. */
1713 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1716 * We don't want to listen forever unless the other side
1717 * successfully authenticates itself. So we set up an alarm which is
1718 * cleared after successful authentication. A limit of zero
1719 * indicates no limit. Note that we don't set the alarm in debugging
1720 * mode; it is just annoying to have the server exit just when you
1721 * are about to discover the bug.
1723 signal(SIGALRM, grace_alarm_handler);
1725 alarm(options.login_grace_time);
1727 sshd_exchange_identification(sock_in, sock_out);
1729 packet_set_nonblocking();
1731 /* allocate authentication context */
1732 authctxt = xcalloc(1, sizeof(*authctxt));
1734 authctxt->loginmsg = &loginmsg;
1736 /* XXX global for cleanup, access from other modules */
1737 the_authctxt = authctxt;
1739 /* prepare buffer to collect messages to display to user after login */
1740 buffer_init(&loginmsg);
1743 if (privsep_preauth(authctxt) == 1)
1746 /* perform the key exchange */
1747 /* authenticate user and start session */
1750 do_authentication2(authctxt);
1753 do_authentication(authctxt);
1756 * If we use privilege separation, the unprivileged child transfers
1757 * the current keystate and exits
1760 mm_send_keystate(pmonitor);
1766 * Cancel the alarm we set to limit the time taken for
1770 signal(SIGALRM, SIG_DFL);
1771 if (startup_pipe != -1) {
1772 close(startup_pipe);
1776 #ifdef SSH_AUDIT_EVENTS
1777 audit_event(SSH_AUTH_SUCCESS);
1781 * In privilege separation, we fork another child and prepare
1782 * file descriptor passing.
1785 privsep_postauth(authctxt);
1786 /* the monitor process [priv] will not return */
1788 destroy_sensitive_data();
1791 /* Start session. */
1792 do_authenticated(authctxt);
1794 /* The connection has been terminated. */
1795 verbose("Closing connection to %.100s", remote_ip);
1798 if (options.use_pam)
1800 #endif /* USE_PAM */
1802 #ifdef SSH_AUDIT_EVENTS
1803 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1815 * Decrypt session_key_int using our private server key and private host key
1816 * (key with larger modulus first).
1819 ssh1_session_key(BIGNUM *session_key_int)
1823 if (BN_cmp(sensitive_data.server_key->rsa->n,
1824 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1825 /* Server key has bigger modulus. */
1826 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1827 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1828 SSH_KEY_BITS_RESERVED) {
1829 fatal("do_connection: %s: "
1830 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1831 get_remote_ipaddr(),
1832 BN_num_bits(sensitive_data.server_key->rsa->n),
1833 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1834 SSH_KEY_BITS_RESERVED);
1836 if (rsa_private_decrypt(session_key_int, session_key_int,
1837 sensitive_data.server_key->rsa) <= 0)
1839 if (rsa_private_decrypt(session_key_int, session_key_int,
1840 sensitive_data.ssh1_host_key->rsa) <= 0)
1843 /* Host key has bigger modulus (or they are equal). */
1844 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1845 BN_num_bits(sensitive_data.server_key->rsa->n) +
1846 SSH_KEY_BITS_RESERVED) {
1847 fatal("do_connection: %s: "
1848 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1849 get_remote_ipaddr(),
1850 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1851 BN_num_bits(sensitive_data.server_key->rsa->n),
1852 SSH_KEY_BITS_RESERVED);
1854 if (rsa_private_decrypt(session_key_int, session_key_int,
1855 sensitive_data.ssh1_host_key->rsa) < 0)
1857 if (rsa_private_decrypt(session_key_int, session_key_int,
1858 sensitive_data.server_key->rsa) < 0)
1871 BIGNUM *session_key_int;
1872 u_char session_key[SSH_SESSION_KEY_LENGTH];
1874 u_int cipher_type, auth_mask, protocol_flags;
1878 * Generate check bytes that the client must send back in the user
1879 * packet in order for it to be accepted; this is used to defy ip
1880 * spoofing attacks. Note that this only works against somebody
1881 * doing IP spoofing from a remote machine; any machine on the local
1882 * network can still see outgoing packets and catch the random
1883 * cookie. This only affects rhosts authentication, and this is one
1884 * of the reasons why it is inherently insecure.
1886 for (i = 0; i < 8; i++) {
1889 cookie[i] = rnd & 0xff;
1894 * Send our public key. We include in the packet 64 bits of random
1895 * data that must be matched in the reply in order to prevent IP
1898 packet_start(SSH_SMSG_PUBLIC_KEY);
1899 for (i = 0; i < 8; i++)
1900 packet_put_char(cookie[i]);
1902 /* Store our public server RSA key. */
1903 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1904 packet_put_bignum(sensitive_data.server_key->rsa->e);
1905 packet_put_bignum(sensitive_data.server_key->rsa->n);
1907 /* Store our public host RSA key. */
1908 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1909 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1910 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1912 /* Put protocol flags. */
1913 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1915 /* Declare which ciphers we support. */
1916 packet_put_int(cipher_mask_ssh1(0));
1918 /* Declare supported authentication types. */
1920 if (options.rhosts_rsa_authentication)
1921 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1922 if (options.rsa_authentication)
1923 auth_mask |= 1 << SSH_AUTH_RSA;
1924 if (options.challenge_response_authentication == 1)
1925 auth_mask |= 1 << SSH_AUTH_TIS;
1926 if (options.password_authentication)
1927 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1928 packet_put_int(auth_mask);
1930 /* Send the packet and wait for it to be sent. */
1932 packet_write_wait();
1934 debug("Sent %d bit server key and %d bit host key.",
1935 BN_num_bits(sensitive_data.server_key->rsa->n),
1936 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1938 /* Read clients reply (cipher type and session key). */
1939 packet_read_expect(SSH_CMSG_SESSION_KEY);
1941 /* Get cipher type and check whether we accept this. */
1942 cipher_type = packet_get_char();
1944 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1945 packet_disconnect("Warning: client selects unsupported cipher.");
1947 /* Get check bytes from the packet. These must match those we
1948 sent earlier with the public key packet. */
1949 for (i = 0; i < 8; i++)
1950 if (cookie[i] != packet_get_char())
1951 packet_disconnect("IP Spoofing check bytes do not match.");
1953 debug("Encryption type: %.200s", cipher_name(cipher_type));
1955 /* Get the encrypted integer. */
1956 if ((session_key_int = BN_new()) == NULL)
1957 fatal("do_ssh1_kex: BN_new failed");
1958 packet_get_bignum(session_key_int);
1960 protocol_flags = packet_get_int();
1961 packet_set_protocol_flags(protocol_flags);
1964 /* Decrypt session_key_int using host/server keys */
1965 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1968 * Extract session key from the decrypted integer. The key is in the
1969 * least significant 256 bits of the integer; the first byte of the
1970 * key is in the highest bits.
1973 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1974 len = BN_num_bytes(session_key_int);
1975 if (len < 0 || (u_int)len > sizeof(session_key)) {
1976 error("do_connection: bad session key len from %s: "
1977 "session_key_int %d > sizeof(session_key) %lu",
1978 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1981 memset(session_key, 0, sizeof(session_key));
1982 BN_bn2bin(session_key_int,
1983 session_key + sizeof(session_key) - len);
1985 derive_ssh1_session_id(
1986 sensitive_data.ssh1_host_key->rsa->n,
1987 sensitive_data.server_key->rsa->n,
1988 cookie, session_id);
1990 * Xor the first 16 bytes of the session key with the
1993 for (i = 0; i < 16; i++)
1994 session_key[i] ^= session_id[i];
1998 int bytes = BN_num_bytes(session_key_int);
1999 u_char *buf = xmalloc(bytes);
2002 logit("do_connection: generating a fake encryption key");
2003 BN_bn2bin(session_key_int, buf);
2005 MD5_Update(&md, buf, bytes);
2006 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2007 MD5_Final(session_key, &md);
2009 MD5_Update(&md, session_key, 16);
2010 MD5_Update(&md, buf, bytes);
2011 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2012 MD5_Final(session_key + 16, &md);
2013 memset(buf, 0, bytes);
2015 for (i = 0; i < 16; i++)
2016 session_id[i] = session_key[i] ^ session_key[i + 16];
2018 /* Destroy the private and public keys. No longer. */
2019 destroy_sensitive_data();
2022 mm_ssh1_session_id(session_id);
2024 /* Destroy the decrypted integer. It is no longer needed. */
2025 BN_clear_free(session_key_int);
2027 /* Set the session key. From this on all communications will be encrypted. */
2028 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2030 /* Destroy our copy of the session key. It is no longer needed. */
2031 memset(session_key, 0, sizeof(session_key));
2033 debug("Received session key; encryption turned on.");
2035 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2036 packet_start(SSH_SMSG_SUCCESS);
2038 packet_write_wait();
2042 * SSH2 key exchange: diffie-hellman-group1-sha1
2049 if (options.ciphers != NULL) {
2050 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2051 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2053 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2054 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2055 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2056 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2058 if (options.macs != NULL) {
2059 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2060 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2062 if (options.compression == COMP_NONE) {
2063 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2064 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2065 } else if (options.compression == COMP_DELAYED) {
2066 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2067 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2070 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2072 /* start key exchange */
2073 kex = kex_setup(myproposal);
2074 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2075 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2076 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2077 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2079 kex->client_version_string=client_version_string;
2080 kex->server_version_string=server_version_string;
2081 kex->load_host_key=&get_hostkey_by_type;
2082 kex->host_key_index=&get_hostkey_index;
2086 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2088 session_id2 = kex->session_id;
2089 session_id2_len = kex->session_id_len;
2092 /* send 1st encrypted/maced/compressed message */
2093 packet_start(SSH2_MSG_IGNORE);
2094 packet_put_cstring("markus");
2096 packet_write_wait();
2101 /* server specific fatal cleanup */
2106 do_cleanup(the_authctxt);
2107 #ifdef SSH_AUDIT_EVENTS
2108 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2109 if (!use_privsep || mm_is_monitor())
2110 audit_event(SSH_CONNECTION_ABANDON);