1 /* $OpenBSD: sshd.c,v 1.342 2006/08/01 23:22:48 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>
71 #include <openssl/dh.h>
72 #include <openssl/bn.h>
73 #include <openssl/md5.h>
74 #include <openssl/rand.h>
75 #ifdef HAVE_SECUREWARE
76 #include <sys/security.h>
97 #include "myproposal.h"
99 #include "pathnames.h"
100 #include "atomicio.h"
101 #include "canohost.h"
105 #include "dispatch.h"
106 #include "channels.h"
108 #include "monitor_mm.h"
110 #include "monitor_wrap.h"
111 #include "monitor_fdpass.h"
117 int allow_severity = LOG_INFO;
118 int deny_severity = LOG_WARNING;
126 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
127 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
128 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
129 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
131 extern char *__progname;
133 /* Server configuration options. */
134 ServerOptions options;
136 /* Name of the server configuration file. */
137 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
140 * Debug mode flag. This can be set on the command line. If debug
141 * mode is enabled, extra debugging output will be sent to the system
142 * log, the daemon will not go to background, and will exit after processing
143 * the first connection.
147 /* Flag indicating that the daemon should only test the configuration and keys. */
150 /* Flag indicating that the daemon is being started from inetd. */
153 /* Flag indicating that sshd should not detach and become a daemon. */
154 int no_daemon_flag = 0;
156 /* debug goes to stderr unless inetd_flag is set */
159 /* Saved arguments to main(). */
164 int rexeced_flag = 0;
170 * The sockets that the server is listening; this is used in the SIGHUP
173 #define MAX_LISTEN_SOCKS 16
174 int listen_socks[MAX_LISTEN_SOCKS];
175 int num_listen_socks = 0;
178 * the client's version string, passed by sshd2 in compat mode. if != NULL,
179 * sshd will skip the version-number exchange
181 char *client_version_string = NULL;
182 char *server_version_string = NULL;
184 /* for rekeying XXX fixme */
188 * Any really sensitive data in the application is contained in this
189 * structure. The idea is that this structure could be locked into memory so
190 * that the pages do not get written into swap. However, there are some
191 * problems. The private key contains BIGNUMs, and we do not (in principle)
192 * have access to the internals of them, and locking just the structure is
193 * not very useful. Currently, memory locking is not implemented.
196 Key *server_key; /* ephemeral server key */
197 Key *ssh1_host_key; /* ssh1 host key */
198 Key **host_keys; /* all private host keys */
201 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
205 * Flag indicating whether the RSA server key needs to be regenerated.
206 * Is set in the SIGALRM handler and cleared when the key is regenerated.
208 static volatile sig_atomic_t key_do_regen = 0;
210 /* This is set to true when a signal is received. */
211 static volatile sig_atomic_t received_sighup = 0;
212 static volatile sig_atomic_t received_sigterm = 0;
214 /* session identifier, used by RSA-auth */
215 u_char session_id[16];
218 u_char *session_id2 = NULL;
219 u_int session_id2_len = 0;
221 /* record remote hostname or ip */
222 u_int utmp_len = MAXHOSTNAMELEN;
224 /* options.max_startup sized array of fd ints */
225 int *startup_pipes = NULL;
226 int startup_pipe; /* in child */
228 /* variables used for privilege separation */
229 int use_privsep = -1;
230 struct monitor *pmonitor = NULL;
232 /* global authentication context */
233 Authctxt *the_authctxt = NULL;
235 /* sshd_config buffer */
238 /* message to be displayed after login */
241 /* Prototypes for various functions defined later in this file. */
242 void destroy_sensitive_data(void);
243 void demote_sensitive_data(void);
245 static void do_ssh1_kex(void);
246 static void do_ssh2_kex(void);
249 * Close all listening sockets
252 close_listen_socks(void)
256 for (i = 0; i < num_listen_socks; i++)
257 close(listen_socks[i]);
258 num_listen_socks = -1;
262 close_startup_pipes(void)
267 for (i = 0; i < options.max_startups; i++)
268 if (startup_pipes[i] != -1)
269 close(startup_pipes[i]);
273 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
274 * the effect is to reread the configuration file (and to regenerate
280 sighup_handler(int sig)
282 int save_errno = errno;
285 signal(SIGHUP, sighup_handler);
290 * Called from the main program after receiving SIGHUP.
291 * Restarts the server.
296 logit("Received SIGHUP; restarting.");
297 close_listen_socks();
298 close_startup_pipes();
299 execv(saved_argv[0], saved_argv);
300 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
306 * Generic signal handler for terminating signals in the master daemon.
310 sigterm_handler(int sig)
312 received_sigterm = sig;
316 * SIGCHLD handler. This is called whenever a child dies. This will then
317 * reap any zombies left by exited children.
321 main_sigchld_handler(int sig)
323 int save_errno = errno;
327 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
328 (pid < 0 && errno == EINTR))
331 signal(SIGCHLD, main_sigchld_handler);
336 * Signal handler for the alarm after the login grace period has expired.
340 grace_alarm_handler(int sig)
342 /* XXX no idea how fix this signal handler */
344 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
345 kill(pmonitor->m_pid, SIGALRM);
347 /* Log error and exit. */
348 fatal("Timeout before authentication for %s", get_remote_ipaddr());
352 * Signal handler for the key regeneration alarm. Note that this
353 * alarm only occurs in the daemon waiting for connections, and it does not
354 * do anything with the private key or random state before forking.
355 * Thus there should be no concurrency control/asynchronous execution
359 generate_ephemeral_server_key(void)
364 verbose("Generating %s%d bit RSA key.",
365 sensitive_data.server_key ? "new " : "", options.server_key_bits);
366 if (sensitive_data.server_key != NULL)
367 key_free(sensitive_data.server_key);
368 sensitive_data.server_key = key_generate(KEY_RSA1,
369 options.server_key_bits);
370 verbose("RSA key generation complete.");
372 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
375 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
383 key_regeneration_alarm(int sig)
385 int save_errno = errno;
387 signal(SIGALRM, SIG_DFL);
393 sshd_exchange_identification(int sock_in, int sock_out)
397 int remote_major, remote_minor;
400 char buf[256]; /* Must not be larger than remote_version. */
401 char remote_version[256]; /* Must be at least as big as buf. */
403 if ((options.protocol & SSH_PROTO_1) &&
404 (options.protocol & SSH_PROTO_2)) {
405 major = PROTOCOL_MAJOR_1;
407 } else if (options.protocol & SSH_PROTO_2) {
408 major = PROTOCOL_MAJOR_2;
409 minor = PROTOCOL_MINOR_2;
411 major = PROTOCOL_MAJOR_1;
412 minor = PROTOCOL_MINOR_1;
414 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
415 server_version_string = xstrdup(buf);
417 /* Send our protocol version identification. */
418 if (atomicio(vwrite, sock_out, server_version_string,
419 strlen(server_version_string))
420 != strlen(server_version_string)) {
421 logit("Could not write ident string to %s", get_remote_ipaddr());
425 /* Read other sides version identification. */
426 memset(buf, 0, sizeof(buf));
427 for (i = 0; i < sizeof(buf) - 1; i++) {
428 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
429 logit("Did not receive identification string from %s",
430 get_remote_ipaddr());
433 if (buf[i] == '\r') {
435 /* Kludge for F-Secure Macintosh < 1.0.2 */
437 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
441 if (buf[i] == '\n') {
446 buf[sizeof(buf) - 1] = 0;
447 client_version_string = xstrdup(buf);
450 * Check that the versions match. In future this might accept
451 * several versions and set appropriate flags to handle them.
453 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
454 &remote_major, &remote_minor, remote_version) != 3) {
455 s = "Protocol mismatch.\n";
456 (void) atomicio(vwrite, sock_out, s, strlen(s));
459 logit("Bad protocol version identification '%.100s' from %s",
460 client_version_string, get_remote_ipaddr());
463 debug("Client protocol version %d.%d; client software version %.100s",
464 remote_major, remote_minor, remote_version);
466 compat_datafellows(remote_version);
468 if (datafellows & SSH_BUG_PROBE) {
469 logit("probed from %s with %s. Don't panic.",
470 get_remote_ipaddr(), client_version_string);
474 if (datafellows & SSH_BUG_SCANNER) {
475 logit("scanned from %s with %s. Don't panic.",
476 get_remote_ipaddr(), client_version_string);
481 switch (remote_major) {
483 if (remote_minor == 99) {
484 if (options.protocol & SSH_PROTO_2)
490 if (!(options.protocol & SSH_PROTO_1)) {
494 if (remote_minor < 3) {
495 packet_disconnect("Your ssh version is too old and "
496 "is no longer supported. Please install a newer version.");
497 } else if (remote_minor == 3) {
498 /* note that this disables agent-forwarding */
503 if (options.protocol & SSH_PROTO_2) {
512 chop(server_version_string);
513 debug("Local version string %.200s", server_version_string);
516 s = "Protocol major versions differ.\n";
517 (void) atomicio(vwrite, sock_out, s, strlen(s));
520 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
522 server_version_string, client_version_string);
527 /* Destroy the host and server keys. They will no longer be needed. */
529 destroy_sensitive_data(void)
533 if (sensitive_data.server_key) {
534 key_free(sensitive_data.server_key);
535 sensitive_data.server_key = NULL;
537 for (i = 0; i < options.num_host_key_files; i++) {
538 if (sensitive_data.host_keys[i]) {
539 key_free(sensitive_data.host_keys[i]);
540 sensitive_data.host_keys[i] = NULL;
543 sensitive_data.ssh1_host_key = NULL;
544 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
547 /* Demote private to public keys for network child */
549 demote_sensitive_data(void)
554 if (sensitive_data.server_key) {
555 tmp = key_demote(sensitive_data.server_key);
556 key_free(sensitive_data.server_key);
557 sensitive_data.server_key = tmp;
560 for (i = 0; i < options.num_host_key_files; i++) {
561 if (sensitive_data.host_keys[i]) {
562 tmp = key_demote(sensitive_data.host_keys[i]);
563 key_free(sensitive_data.host_keys[i]);
564 sensitive_data.host_keys[i] = tmp;
565 if (tmp->type == KEY_RSA1)
566 sensitive_data.ssh1_host_key = tmp;
570 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
574 privsep_preauth_child(void)
581 /* Enable challenge-response authentication for privilege separation */
582 privsep_challenge_enable();
584 for (i = 0; i < 256; i++)
585 rnd[i] = arc4random();
586 RAND_seed(rnd, sizeof(rnd));
588 /* Demote the private keys to public keys. */
589 demote_sensitive_data();
591 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
592 fatal("Privilege separation user %s does not exist",
594 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
597 /* Change our root directory */
598 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
599 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
601 if (chdir("/") == -1)
602 fatal("chdir(\"/\"): %s", strerror(errno));
604 /* Drop our privileges */
605 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
608 /* XXX not ready, too heavy after chroot */
609 do_setusercontext(pw);
611 gidset[0] = pw->pw_gid;
612 if (setgroups(1, gidset) < 0)
613 fatal("setgroups: %.100s", strerror(errno));
614 permanently_set_uid(pw);
619 privsep_preauth(Authctxt *authctxt)
624 /* Set up unprivileged child process to deal with network data */
625 pmonitor = monitor_init();
626 /* Store a pointer to the kex for later rekeying */
627 pmonitor->m_pkex = &xxx_kex;
631 fatal("fork of unprivileged child failed");
632 } else if (pid != 0) {
633 debug2("Network child is on pid %ld", (long)pid);
635 close(pmonitor->m_recvfd);
636 pmonitor->m_pid = pid;
637 monitor_child_preauth(authctxt, pmonitor);
638 close(pmonitor->m_sendfd);
641 monitor_sync(pmonitor);
643 /* Wait for the child's exit status */
644 while (waitpid(pid, &status, 0) < 0)
651 close(pmonitor->m_sendfd);
653 /* Demote the child */
654 if (getuid() == 0 || geteuid() == 0)
655 privsep_preauth_child();
656 setproctitle("%s", "[net]");
662 privsep_postauth(Authctxt *authctxt)
664 #ifdef DISABLE_FD_PASSING
667 if (authctxt->pw->pw_uid == 0 || options.use_login) {
669 /* File descriptor passing is broken or root login */
674 /* New socket pair */
675 monitor_reinit(pmonitor);
677 pmonitor->m_pid = fork();
678 if (pmonitor->m_pid == -1)
679 fatal("fork of unprivileged child failed");
680 else if (pmonitor->m_pid != 0) {
681 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
682 close(pmonitor->m_recvfd);
683 buffer_clear(&loginmsg);
684 monitor_child_postauth(pmonitor);
690 close(pmonitor->m_sendfd);
692 /* Demote the private keys to public keys. */
693 demote_sensitive_data();
695 /* Drop privileges */
696 do_setusercontext(authctxt->pw);
699 /* It is safe now to apply the key state */
700 monitor_apply_keystate(pmonitor);
703 * Tell the packet layer that authentication was successful, since
704 * this information is not part of the key state.
706 packet_set_authenticated();
710 list_hostkey_types(void)
718 for (i = 0; i < options.num_host_key_files; i++) {
719 Key *key = sensitive_data.host_keys[i];
725 if (buffer_len(&b) > 0)
726 buffer_append(&b, ",", 1);
727 p = key_ssh_name(key);
728 buffer_append(&b, p, strlen(p));
732 buffer_append(&b, "\0", 1);
733 ret = xstrdup(buffer_ptr(&b));
735 debug("list_hostkey_types: %s", ret);
740 get_hostkey_by_type(int type)
744 for (i = 0; i < options.num_host_key_files; i++) {
745 Key *key = sensitive_data.host_keys[i];
746 if (key != NULL && key->type == type)
753 get_hostkey_by_index(int ind)
755 if (ind < 0 || ind >= options.num_host_key_files)
757 return (sensitive_data.host_keys[ind]);
761 get_hostkey_index(Key *key)
765 for (i = 0; i < options.num_host_key_files; i++) {
766 if (key == sensitive_data.host_keys[i])
773 * returns 1 if connection should be dropped, 0 otherwise.
774 * dropping starts at connection #max_startups_begin with a probability
775 * of (max_startups_rate/100). the probability increases linearly until
776 * all connections are dropped for startups > max_startups
779 drop_connection(int startups)
783 if (startups < options.max_startups_begin)
785 if (startups >= options.max_startups)
787 if (options.max_startups_rate == 100)
790 p = 100 - options.max_startups_rate;
791 p *= startups - options.max_startups_begin;
792 p /= options.max_startups - options.max_startups_begin;
793 p += options.max_startups_rate;
794 r = arc4random() % 100;
796 debug("drop_connection: p %d, r %d", p, r);
797 return (r < p) ? 1 : 0;
803 fprintf(stderr, "%s, %s\n",
804 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
806 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
807 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
813 send_rexec_state(int fd, Buffer *conf)
817 debug3("%s: entering fd = %d config len %d", __func__, fd,
821 * Protocol from reexec master to child:
822 * string configuration
823 * u_int ephemeral_key_follows
824 * bignum e (only if ephemeral_key_follows == 1)
830 * string rngseed (only if OpenSSL is not self-seeded)
833 buffer_put_cstring(&m, buffer_ptr(conf));
835 if (sensitive_data.server_key != NULL &&
836 sensitive_data.server_key->type == KEY_RSA1) {
837 buffer_put_int(&m, 1);
838 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
839 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
840 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
841 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
842 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
843 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
845 buffer_put_int(&m, 0);
847 #ifndef OPENSSL_PRNG_ONLY
848 rexec_send_rng_seed(&m);
851 if (ssh_msg_send(fd, 0, &m) == -1)
852 fatal("%s: ssh_msg_send failed", __func__);
856 debug3("%s: done", __func__);
860 recv_rexec_state(int fd, Buffer *conf)
866 debug3("%s: entering fd = %d", __func__, fd);
870 if (ssh_msg_recv(fd, &m) == -1)
871 fatal("%s: ssh_msg_recv failed", __func__);
872 if (buffer_get_char(&m) != 0)
873 fatal("%s: rexec version mismatch", __func__);
875 cp = buffer_get_string(&m, &len);
877 buffer_append(conf, cp, len + 1);
880 if (buffer_get_int(&m)) {
881 if (sensitive_data.server_key != NULL)
882 key_free(sensitive_data.server_key);
883 sensitive_data.server_key = key_new_private(KEY_RSA1);
884 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
885 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
886 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
887 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
888 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
889 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
890 rsa_generate_additional_parameters(
891 sensitive_data.server_key->rsa);
894 #ifndef OPENSSL_PRNG_ONLY
895 rexec_recv_rng_seed(&m);
900 debug3("%s: done", __func__);
904 * Main program for the daemon.
907 main(int ac, char **av)
911 int opt, j, i, on = 1;
912 int sock_in = -1, sock_out = -1, newsock = -1;
916 struct sockaddr_storage from;
917 const char *remote_ip;
921 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
923 int listen_sock, maxfd;
924 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
928 int ret, key_used = 0;
930 #ifdef HAVE_SECUREWARE
931 (void)set_auth_parameters(ac, av);
933 __progname = ssh_get_progname(av[0]);
936 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
939 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
940 for (i = 0; i < ac; i++)
941 saved_argv[i] = xstrdup(av[i]);
942 saved_argv[i] = NULL;
944 #ifndef HAVE_SETPROCTITLE
945 /* Prepare for later setproctitle emulation */
946 compat_init_setproctitle(ac, av);
950 if (geteuid() == 0 && setgroups(0, NULL) == -1)
951 debug("setgroups(): %.200s", strerror(errno));
953 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
956 /* Initialize configuration options to their default values. */
957 initialize_server_options(&options);
959 /* Parse command-line arguments. */
960 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
963 options.address_family = AF_INET;
966 options.address_family = AF_INET6;
969 config_file_name = optarg;
972 if (debug_flag == 0) {
974 options.log_level = SYSLOG_LEVEL_DEBUG1;
975 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
998 options.log_level = SYSLOG_LEVEL_QUIET;
1001 options.server_key_bits = (int)strtonum(optarg, 256,
1005 options.ports_from_cmdline = 1;
1006 if (options.num_ports >= MAX_PORTS) {
1007 fprintf(stderr, "too many ports.\n");
1010 options.ports[options.num_ports++] = a2port(optarg);
1011 if (options.ports[options.num_ports-1] == 0) {
1012 fprintf(stderr, "Bad port number.\n");
1017 if ((options.login_grace_time = convtime(optarg)) == -1) {
1018 fprintf(stderr, "Invalid login grace time.\n");
1023 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1024 fprintf(stderr, "Invalid key regeneration interval.\n");
1029 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1030 fprintf(stderr, "too many host keys.\n");
1033 options.host_key_files[options.num_host_key_files++] = optarg;
1039 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1040 if (utmp_len > MAXHOSTNAMELEN) {
1041 fprintf(stderr, "Invalid utmp length.\n");
1046 line = xstrdup(optarg);
1047 if (process_server_config_line(&options, line,
1048 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1058 if (rexeced_flag || inetd_flag)
1060 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1061 fatal("sshd re-exec requires execution with an absolute path");
1063 closefrom(REEXEC_MIN_FREE_FD);
1065 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1067 SSLeay_add_all_algorithms();
1070 * Force logging to stderr until we have loaded the private host
1071 * key (unless started from inetd)
1073 log_init(__progname,
1074 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1075 SYSLOG_LEVEL_INFO : options.log_level,
1076 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1077 SYSLOG_FACILITY_AUTH : options.log_facility,
1078 log_stderr || !inetd_flag);
1081 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1082 * root's environment
1084 if (getenv("KRB5CCNAME") != NULL)
1085 unsetenv("KRB5CCNAME");
1088 /* Cray can define user privs drop all privs now!
1089 * Not needed on PRIV_SU systems!
1094 sensitive_data.server_key = NULL;
1095 sensitive_data.ssh1_host_key = NULL;
1096 sensitive_data.have_ssh1_key = 0;
1097 sensitive_data.have_ssh2_key = 0;
1099 /* Fetch our configuration */
1102 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1104 load_server_config(config_file_name, &cfg);
1106 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1107 &cfg, NULL, NULL, NULL);
1111 /* Fill in default values for those options not explicitly set. */
1112 fill_default_server_options(&options);
1114 /* set default channel AF */
1115 channel_set_af(options.address_family);
1117 /* Check that there are no remaining arguments. */
1119 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1123 debug("sshd version %.100s", SSH_RELEASE);
1125 /* load private host keys */
1126 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1128 for (i = 0; i < options.num_host_key_files; i++)
1129 sensitive_data.host_keys[i] = NULL;
1131 for (i = 0; i < options.num_host_key_files; i++) {
1132 key = key_load_private(options.host_key_files[i], "", NULL);
1133 sensitive_data.host_keys[i] = key;
1135 error("Could not load host key: %s",
1136 options.host_key_files[i]);
1137 sensitive_data.host_keys[i] = NULL;
1140 switch (key->type) {
1142 sensitive_data.ssh1_host_key = key;
1143 sensitive_data.have_ssh1_key = 1;
1147 sensitive_data.have_ssh2_key = 1;
1150 debug("private host key: #%d type %d %s", i, key->type,
1153 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1154 logit("Disabling protocol version 1. Could not load host key");
1155 options.protocol &= ~SSH_PROTO_1;
1157 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1158 logit("Disabling protocol version 2. Could not load host key");
1159 options.protocol &= ~SSH_PROTO_2;
1161 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1162 logit("sshd: no hostkeys available -- exiting.");
1166 /* Check certain values for sanity. */
1167 if (options.protocol & SSH_PROTO_1) {
1168 if (options.server_key_bits < 512 ||
1169 options.server_key_bits > 32768) {
1170 fprintf(stderr, "Bad server key size.\n");
1174 * Check that server and host key lengths differ sufficiently. This
1175 * is necessary to make double encryption work with rsaref. Oh, I
1176 * hate software patents. I dont know if this can go? Niels
1178 if (options.server_key_bits >
1179 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1180 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1181 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1182 SSH_KEY_BITS_RESERVED) {
1183 options.server_key_bits =
1184 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1185 SSH_KEY_BITS_RESERVED;
1186 debug("Forcing server key to %d bits to make it differ from host key.",
1187 options.server_key_bits);
1194 if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1195 fatal("Privilege separation user %s does not exist",
1197 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1198 (S_ISDIR(st.st_mode) == 0))
1199 fatal("Missing privilege separation directory: %s",
1200 _PATH_PRIVSEP_CHROOT_DIR);
1203 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1204 (st.st_uid != getuid () ||
1205 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1207 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1209 fatal("%s must be owned by root and not group or "
1210 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1213 /* Configuration looks good, so exit if in test mode. */
1218 * Clear out any supplemental groups we may have inherited. This
1219 * prevents inadvertent creation of files with bad modes (in the
1220 * portable version at least, it's certainly possible for PAM
1221 * to create a file, and we can't control the code in every
1222 * module which might be used).
1224 if (setgroups(0, NULL) < 0)
1225 debug("setgroups() failed: %.200s", strerror(errno));
1228 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1229 for (i = 0; i < rexec_argc; i++) {
1230 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1231 rexec_argv[i] = saved_argv[i];
1233 rexec_argv[rexec_argc] = "-R";
1234 rexec_argv[rexec_argc + 1] = NULL;
1237 /* Initialize the log (it is reinitialized below in case we forked). */
1238 if (debug_flag && (!inetd_flag || rexeced_flag))
1240 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1243 * If not in debugging mode, and not started from inetd, disconnect
1244 * from the controlling terminal, and fork. The original process
1247 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1250 #endif /* TIOCNOTTY */
1251 if (daemon(0, 0) < 0)
1252 fatal("daemon() failed: %.200s", strerror(errno));
1254 /* Disconnect from the controlling tty. */
1256 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1258 (void) ioctl(fd, TIOCNOTTY, NULL);
1261 #endif /* TIOCNOTTY */
1263 /* Reinitialize the log (because of the fork above). */
1264 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1266 /* Initialize the random number generator. */
1269 /* Chdir to the root directory so that the current disk can be
1270 unmounted if desired. */
1273 /* ignore SIGPIPE */
1274 signal(SIGPIPE, SIG_IGN);
1276 /* Start listening for a socket, unless started from inetd. */
1282 close(REEXEC_CONFIG_PASS_FD);
1283 sock_in = sock_out = dup(STDIN_FILENO);
1285 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1286 close(REEXEC_STARTUP_PIPE_FD);
1289 sock_in = dup(STDIN_FILENO);
1290 sock_out = dup(STDOUT_FILENO);
1293 * We intentionally do not close the descriptors 0, 1, and 2
1294 * as our code for setting the descriptors won't work if
1295 * ttyfd happens to be one of those.
1297 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1298 dup2(fd, STDIN_FILENO);
1299 dup2(fd, STDOUT_FILENO);
1300 if (fd > STDOUT_FILENO)
1303 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1304 if ((options.protocol & SSH_PROTO_1) &&
1305 sensitive_data.server_key == NULL)
1306 generate_ephemeral_server_key();
1308 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1309 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1311 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1312 fatal("Too many listen sockets. "
1313 "Enlarge MAX_LISTEN_SOCKS");
1314 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1315 ntop, sizeof(ntop), strport, sizeof(strport),
1316 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1317 error("getnameinfo failed: %.100s",
1318 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1322 /* Create socket for listening. */
1323 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1325 if (listen_sock < 0) {
1326 /* kernel may not support ipv6 */
1327 verbose("socket: %.100s", strerror(errno));
1330 if (set_nonblock(listen_sock) == -1) {
1335 * Set socket options.
1336 * Allow local port reuse in TIME_WAIT.
1338 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1339 &on, sizeof(on)) == -1)
1340 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1342 debug("Bind to port %s on %s.", strport, ntop);
1344 /* Bind the socket to the desired port. */
1345 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1347 error("Bind to port %s on %s failed: %.200s.",
1348 strport, ntop, strerror(errno));
1352 listen_socks[num_listen_socks] = listen_sock;
1355 /* Start listening on the port. */
1356 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1357 fatal("listen on [%s]:%s: %.100s",
1358 ntop, strport, strerror(errno));
1359 logit("Server listening on %s port %s.", ntop, strport);
1361 freeaddrinfo(options.listen_addrs);
1363 if (!num_listen_socks)
1364 fatal("Cannot bind any address.");
1366 if (options.protocol & SSH_PROTO_1)
1367 generate_ephemeral_server_key();
1370 * Arrange to restart on SIGHUP. The handler needs
1373 signal(SIGHUP, sighup_handler);
1375 signal(SIGTERM, sigterm_handler);
1376 signal(SIGQUIT, sigterm_handler);
1378 /* Arrange SIGCHLD to be caught. */
1379 signal(SIGCHLD, main_sigchld_handler);
1381 /* Write out the pid file after the sigterm handler is setup */
1384 * Record our pid in /var/run/sshd.pid to make it
1385 * easier to kill the correct sshd. We don't want to
1386 * do this before the bind above because the bind will
1387 * fail if there already is a daemon, and this will
1388 * overwrite any old pid in the file.
1390 f = fopen(options.pid_file, "wb");
1392 error("Couldn't create pid file \"%s\": %s",
1393 options.pid_file, strerror(errno));
1395 fprintf(f, "%ld\n", (long) getpid());
1400 /* setup fd set for listen */
1403 for (i = 0; i < num_listen_socks; i++)
1404 if (listen_socks[i] > maxfd)
1405 maxfd = listen_socks[i];
1406 /* pipes connected to unauthenticated childs */
1407 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1408 for (i = 0; i < options.max_startups; i++)
1409 startup_pipes[i] = -1;
1412 * Stay listening for connections until the system crashes or
1413 * the daemon is killed with a signal.
1416 if (received_sighup)
1420 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1423 for (i = 0; i < num_listen_socks; i++)
1424 FD_SET(listen_socks[i], fdset);
1425 for (i = 0; i < options.max_startups; i++)
1426 if (startup_pipes[i] != -1)
1427 FD_SET(startup_pipes[i], fdset);
1429 /* Wait in select until there is a connection. */
1430 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1431 if (ret < 0 && errno != EINTR)
1432 error("select: %.100s", strerror(errno));
1433 if (received_sigterm) {
1434 logit("Received signal %d; terminating.",
1435 (int) received_sigterm);
1436 close_listen_socks();
1437 unlink(options.pid_file);
1440 if (key_used && key_do_regen) {
1441 generate_ephemeral_server_key();
1448 for (i = 0; i < options.max_startups; i++)
1449 if (startup_pipes[i] != -1 &&
1450 FD_ISSET(startup_pipes[i], fdset)) {
1452 * the read end of the pipe is ready
1453 * if the child has closed the pipe
1454 * after successful authentication
1455 * or if the child has died
1457 close(startup_pipes[i]);
1458 startup_pipes[i] = -1;
1461 for (i = 0; i < num_listen_socks; i++) {
1462 if (!FD_ISSET(listen_socks[i], fdset))
1464 fromlen = sizeof(from);
1465 newsock = accept(listen_socks[i],
1466 (struct sockaddr *)&from, &fromlen);
1468 if (errno != EINTR && errno != EWOULDBLOCK)
1469 error("accept: %.100s", strerror(errno));
1472 if (unset_nonblock(newsock) == -1) {
1476 if (drop_connection(startups) == 1) {
1477 debug("drop connection #%d", startups);
1481 if (pipe(startup_p) == -1) {
1486 if (rexec_flag && socketpair(AF_UNIX,
1487 SOCK_STREAM, 0, config_s) == -1) {
1488 error("reexec socketpair: %s",
1491 close(startup_p[0]);
1492 close(startup_p[1]);
1496 for (j = 0; j < options.max_startups; j++)
1497 if (startup_pipes[j] == -1) {
1498 startup_pipes[j] = startup_p[0];
1499 if (maxfd < startup_p[0])
1500 maxfd = startup_p[0];
1506 * Got connection. Fork a child to handle it, unless
1507 * we are in debugging mode.
1511 * In debugging mode. Close the listening
1512 * socket, and start processing the
1513 * connection without forking.
1515 debug("Server will not fork when running in debugging mode.");
1516 close_listen_socks();
1519 close(startup_p[0]);
1520 close(startup_p[1]);
1524 send_rexec_state(config_s[0],
1531 * Normal production daemon. Fork, and have
1532 * the child process the connection. The
1533 * parent continues listening.
1535 if ((pid = fork()) == 0) {
1537 * Child. Close the listening and
1538 * max_startup sockets. Start using
1539 * the accepted socket. Reinitialize
1540 * logging (since our pid has changed).
1541 * We break out of the loop to handle
1544 startup_pipe = startup_p[1];
1545 close_startup_pipes();
1546 close_listen_socks();
1549 log_init(__progname,
1551 options.log_facility,
1559 /* Parent. Stay in the loop. */
1561 error("fork: %.100s", strerror(errno));
1563 debug("Forked child %ld.", (long)pid);
1565 close(startup_p[1]);
1568 send_rexec_state(config_s[0], &cfg);
1574 * Mark that the key has been used (it
1575 * was "given" to the child).
1577 if ((options.protocol & SSH_PROTO_1) &&
1579 /* Schedule server key regeneration alarm. */
1580 signal(SIGALRM, key_regeneration_alarm);
1581 alarm(options.key_regeneration_time);
1588 /* child process check (or debug mode) */
1589 if (num_listen_socks < 0)
1594 /* This is the child processing a new connection. */
1595 setproctitle("%s", "[accepted]");
1598 * Create a new session and process group since the 4.4BSD
1599 * setlogin() affects the entire process group. We don't
1600 * want the child to be able to affect the parent.
1602 #if !defined(SSHD_ACQUIRES_CTTY)
1604 * If setsid is called, on some platforms sshd will later acquire a
1605 * controlling terminal which will result in "could not set
1606 * controlling tty" errors.
1608 if (!debug_flag && !inetd_flag && setsid() < 0)
1609 error("setsid: %.100s", strerror(errno));
1615 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1616 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1617 dup2(newsock, STDIN_FILENO);
1618 dup2(STDIN_FILENO, STDOUT_FILENO);
1619 if (startup_pipe == -1)
1620 close(REEXEC_STARTUP_PIPE_FD);
1622 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1624 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1626 if (startup_pipe != -1)
1627 close(startup_pipe);
1629 execv(rexec_argv[0], rexec_argv);
1631 /* Reexec has failed, fall back and continue */
1632 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1633 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1634 log_init(__progname, options.log_level,
1635 options.log_facility, log_stderr);
1638 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1640 close(REEXEC_CONFIG_PASS_FD);
1641 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1642 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1643 dup2(fd, STDIN_FILENO);
1644 dup2(fd, STDOUT_FILENO);
1645 if (fd > STDERR_FILENO)
1648 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1649 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1653 * Disable the key regeneration alarm. We will not regenerate the
1654 * key since we are no longer in a position to give it to anyone. We
1655 * will not restart on SIGHUP since it no longer makes sense.
1658 signal(SIGALRM, SIG_DFL);
1659 signal(SIGHUP, SIG_DFL);
1660 signal(SIGTERM, SIG_DFL);
1661 signal(SIGQUIT, SIG_DFL);
1662 signal(SIGCHLD, SIG_DFL);
1663 signal(SIGINT, SIG_DFL);
1666 * Register our connection. This turns encryption off because we do
1669 packet_set_connection(sock_in, sock_out);
1670 packet_set_server();
1672 /* Set SO_KEEPALIVE if requested. */
1673 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1674 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1675 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1677 if ((remote_port = get_remote_port()) < 0) {
1678 debug("get_remote_port failed");
1683 * We use get_canonical_hostname with usedns = 0 instead of
1684 * get_remote_ipaddr here so IP options will be checked.
1686 (void) get_canonical_hostname(0);
1688 * The rest of the code depends on the fact that
1689 * get_remote_ipaddr() caches the remote ip, even if
1690 * the socket goes away.
1692 remote_ip = get_remote_ipaddr();
1694 #ifdef SSH_AUDIT_EVENTS
1695 audit_connection_from(remote_ip, remote_port);
1698 /* Check whether logins are denied from this host. */
1699 if (packet_connection_is_on_socket()) {
1700 struct request_info req;
1702 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1705 if (!hosts_access(&req)) {
1706 debug("Connection refused by tcp wrapper");
1709 fatal("libwrap refuse returns");
1712 #endif /* LIBWRAP */
1714 /* Log the connection. */
1715 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1718 * We don't want to listen forever unless the other side
1719 * successfully authenticates itself. So we set up an alarm which is
1720 * cleared after successful authentication. A limit of zero
1721 * indicates no limit. Note that we don't set the alarm in debugging
1722 * mode; it is just annoying to have the server exit just when you
1723 * are about to discover the bug.
1725 signal(SIGALRM, grace_alarm_handler);
1727 alarm(options.login_grace_time);
1729 sshd_exchange_identification(sock_in, sock_out);
1731 packet_set_nonblocking();
1733 /* allocate authentication context */
1734 authctxt = xcalloc(1, sizeof(*authctxt));
1736 authctxt->loginmsg = &loginmsg;
1738 /* XXX global for cleanup, access from other modules */
1739 the_authctxt = authctxt;
1741 /* prepare buffer to collect messages to display to user after login */
1742 buffer_init(&loginmsg);
1745 if (privsep_preauth(authctxt) == 1)
1748 /* perform the key exchange */
1749 /* authenticate user and start session */
1752 do_authentication2(authctxt);
1755 do_authentication(authctxt);
1758 * If we use privilege separation, the unprivileged child transfers
1759 * the current keystate and exits
1762 mm_send_keystate(pmonitor);
1768 * Cancel the alarm we set to limit the time taken for
1772 signal(SIGALRM, SIG_DFL);
1773 if (startup_pipe != -1) {
1774 close(startup_pipe);
1778 #ifdef SSH_AUDIT_EVENTS
1779 audit_event(SSH_AUTH_SUCCESS);
1783 * In privilege separation, we fork another child and prepare
1784 * file descriptor passing.
1787 privsep_postauth(authctxt);
1788 /* the monitor process [priv] will not return */
1790 destroy_sensitive_data();
1793 /* Start session. */
1794 do_authenticated(authctxt);
1796 /* The connection has been terminated. */
1797 verbose("Closing connection to %.100s", remote_ip);
1800 if (options.use_pam)
1802 #endif /* USE_PAM */
1804 #ifdef SSH_AUDIT_EVENTS
1805 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1817 * Decrypt session_key_int using our private server key and private host key
1818 * (key with larger modulus first).
1821 ssh1_session_key(BIGNUM *session_key_int)
1825 if (BN_cmp(sensitive_data.server_key->rsa->n,
1826 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1827 /* Server key has bigger modulus. */
1828 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1829 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1830 SSH_KEY_BITS_RESERVED) {
1831 fatal("do_connection: %s: "
1832 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1833 get_remote_ipaddr(),
1834 BN_num_bits(sensitive_data.server_key->rsa->n),
1835 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1836 SSH_KEY_BITS_RESERVED);
1838 if (rsa_private_decrypt(session_key_int, session_key_int,
1839 sensitive_data.server_key->rsa) <= 0)
1841 if (rsa_private_decrypt(session_key_int, session_key_int,
1842 sensitive_data.ssh1_host_key->rsa) <= 0)
1845 /* Host key has bigger modulus (or they are equal). */
1846 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1847 BN_num_bits(sensitive_data.server_key->rsa->n) +
1848 SSH_KEY_BITS_RESERVED) {
1849 fatal("do_connection: %s: "
1850 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1851 get_remote_ipaddr(),
1852 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1853 BN_num_bits(sensitive_data.server_key->rsa->n),
1854 SSH_KEY_BITS_RESERVED);
1856 if (rsa_private_decrypt(session_key_int, session_key_int,
1857 sensitive_data.ssh1_host_key->rsa) < 0)
1859 if (rsa_private_decrypt(session_key_int, session_key_int,
1860 sensitive_data.server_key->rsa) < 0)
1873 BIGNUM *session_key_int;
1874 u_char session_key[SSH_SESSION_KEY_LENGTH];
1876 u_int cipher_type, auth_mask, protocol_flags;
1880 * Generate check bytes that the client must send back in the user
1881 * packet in order for it to be accepted; this is used to defy ip
1882 * spoofing attacks. Note that this only works against somebody
1883 * doing IP spoofing from a remote machine; any machine on the local
1884 * network can still see outgoing packets and catch the random
1885 * cookie. This only affects rhosts authentication, and this is one
1886 * of the reasons why it is inherently insecure.
1888 for (i = 0; i < 8; i++) {
1891 cookie[i] = rnd & 0xff;
1896 * Send our public key. We include in the packet 64 bits of random
1897 * data that must be matched in the reply in order to prevent IP
1900 packet_start(SSH_SMSG_PUBLIC_KEY);
1901 for (i = 0; i < 8; i++)
1902 packet_put_char(cookie[i]);
1904 /* Store our public server RSA key. */
1905 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1906 packet_put_bignum(sensitive_data.server_key->rsa->e);
1907 packet_put_bignum(sensitive_data.server_key->rsa->n);
1909 /* Store our public host RSA key. */
1910 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1911 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1912 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1914 /* Put protocol flags. */
1915 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1917 /* Declare which ciphers we support. */
1918 packet_put_int(cipher_mask_ssh1(0));
1920 /* Declare supported authentication types. */
1922 if (options.rhosts_rsa_authentication)
1923 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1924 if (options.rsa_authentication)
1925 auth_mask |= 1 << SSH_AUTH_RSA;
1926 if (options.challenge_response_authentication == 1)
1927 auth_mask |= 1 << SSH_AUTH_TIS;
1928 if (options.password_authentication)
1929 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1930 packet_put_int(auth_mask);
1932 /* Send the packet and wait for it to be sent. */
1934 packet_write_wait();
1936 debug("Sent %d bit server key and %d bit host key.",
1937 BN_num_bits(sensitive_data.server_key->rsa->n),
1938 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1940 /* Read clients reply (cipher type and session key). */
1941 packet_read_expect(SSH_CMSG_SESSION_KEY);
1943 /* Get cipher type and check whether we accept this. */
1944 cipher_type = packet_get_char();
1946 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1947 packet_disconnect("Warning: client selects unsupported cipher.");
1949 /* Get check bytes from the packet. These must match those we
1950 sent earlier with the public key packet. */
1951 for (i = 0; i < 8; i++)
1952 if (cookie[i] != packet_get_char())
1953 packet_disconnect("IP Spoofing check bytes do not match.");
1955 debug("Encryption type: %.200s", cipher_name(cipher_type));
1957 /* Get the encrypted integer. */
1958 if ((session_key_int = BN_new()) == NULL)
1959 fatal("do_ssh1_kex: BN_new failed");
1960 packet_get_bignum(session_key_int);
1962 protocol_flags = packet_get_int();
1963 packet_set_protocol_flags(protocol_flags);
1966 /* Decrypt session_key_int using host/server keys */
1967 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1970 * Extract session key from the decrypted integer. The key is in the
1971 * least significant 256 bits of the integer; the first byte of the
1972 * key is in the highest bits.
1975 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1976 len = BN_num_bytes(session_key_int);
1977 if (len < 0 || (u_int)len > sizeof(session_key)) {
1978 error("do_connection: bad session key len from %s: "
1979 "session_key_int %d > sizeof(session_key) %lu",
1980 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1983 memset(session_key, 0, sizeof(session_key));
1984 BN_bn2bin(session_key_int,
1985 session_key + sizeof(session_key) - len);
1987 derive_ssh1_session_id(
1988 sensitive_data.ssh1_host_key->rsa->n,
1989 sensitive_data.server_key->rsa->n,
1990 cookie, session_id);
1992 * Xor the first 16 bytes of the session key with the
1995 for (i = 0; i < 16; i++)
1996 session_key[i] ^= session_id[i];
2000 int bytes = BN_num_bytes(session_key_int);
2001 u_char *buf = xmalloc(bytes);
2004 logit("do_connection: generating a fake encryption key");
2005 BN_bn2bin(session_key_int, buf);
2007 MD5_Update(&md, buf, bytes);
2008 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2009 MD5_Final(session_key, &md);
2011 MD5_Update(&md, session_key, 16);
2012 MD5_Update(&md, buf, bytes);
2013 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2014 MD5_Final(session_key + 16, &md);
2015 memset(buf, 0, bytes);
2017 for (i = 0; i < 16; i++)
2018 session_id[i] = session_key[i] ^ session_key[i + 16];
2020 /* Destroy the private and public keys. No longer. */
2021 destroy_sensitive_data();
2024 mm_ssh1_session_id(session_id);
2026 /* Destroy the decrypted integer. It is no longer needed. */
2027 BN_clear_free(session_key_int);
2029 /* Set the session key. From this on all communications will be encrypted. */
2030 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2032 /* Destroy our copy of the session key. It is no longer needed. */
2033 memset(session_key, 0, sizeof(session_key));
2035 debug("Received session key; encryption turned on.");
2037 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2038 packet_start(SSH_SMSG_SUCCESS);
2040 packet_write_wait();
2044 * SSH2 key exchange: diffie-hellman-group1-sha1
2051 if (options.ciphers != NULL) {
2052 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2053 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2055 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2056 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2057 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2058 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2060 if (options.macs != NULL) {
2061 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2062 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2064 if (options.compression == COMP_NONE) {
2065 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2066 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2067 } else if (options.compression == COMP_DELAYED) {
2068 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2069 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2072 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2074 /* start key exchange */
2075 kex = kex_setup(myproposal);
2076 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2077 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2078 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2079 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2081 kex->client_version_string=client_version_string;
2082 kex->server_version_string=server_version_string;
2083 kex->load_host_key=&get_hostkey_by_type;
2084 kex->host_key_index=&get_hostkey_index;
2088 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2090 session_id2 = kex->session_id;
2091 session_id2_len = kex->session_id_len;
2094 /* send 1st encrypted/maced/compressed message */
2095 packet_start(SSH2_MSG_IGNORE);
2096 packet_put_cstring("markus");
2098 packet_write_wait();
2103 /* server specific fatal cleanup */
2108 do_cleanup(the_authctxt);
2109 #ifdef SSH_AUDIT_EVENTS
2110 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2111 if (!use_privsep || mm_is_monitor())
2112 audit_event(SSH_CONNECTION_ABANDON);