1 /* $OpenBSD: sshd.c,v 1.339 2006/07/22 20:48:23 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>
57 #if defined(HAVE_NETDB_H)
68 #include <openssl/dh.h>
69 #include <openssl/bn.h>
70 #include <openssl/md5.h>
71 #include <openssl/rand.h>
72 #ifdef HAVE_SECUREWARE
73 #include <sys/security.h>
94 #include "myproposal.h"
96 #include "pathnames.h"
102 #include "dispatch.h"
103 #include "channels.h"
105 #include "monitor_mm.h"
107 #include "monitor_wrap.h"
108 #include "monitor_fdpass.h"
114 int allow_severity = LOG_INFO;
115 int deny_severity = LOG_WARNING;
123 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
124 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
125 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
126 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
128 extern char *__progname;
130 /* Server configuration options. */
131 ServerOptions options;
133 /* Name of the server configuration file. */
134 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
137 * Debug mode flag. This can be set on the command line. If debug
138 * mode is enabled, extra debugging output will be sent to the system
139 * log, the daemon will not go to background, and will exit after processing
140 * the first connection.
144 /* Flag indicating that the daemon should only test the configuration and keys. */
147 /* Flag indicating that the daemon is being started from inetd. */
150 /* Flag indicating that sshd should not detach and become a daemon. */
151 int no_daemon_flag = 0;
153 /* debug goes to stderr unless inetd_flag is set */
156 /* Saved arguments to main(). */
161 int rexeced_flag = 0;
167 * The sockets that the server is listening; this is used in the SIGHUP
170 #define MAX_LISTEN_SOCKS 16
171 int listen_socks[MAX_LISTEN_SOCKS];
172 int num_listen_socks = 0;
175 * the client's version string, passed by sshd2 in compat mode. if != NULL,
176 * sshd will skip the version-number exchange
178 char *client_version_string = NULL;
179 char *server_version_string = NULL;
181 /* for rekeying XXX fixme */
185 * Any really sensitive data in the application is contained in this
186 * structure. The idea is that this structure could be locked into memory so
187 * that the pages do not get written into swap. However, there are some
188 * problems. The private key contains BIGNUMs, and we do not (in principle)
189 * have access to the internals of them, and locking just the structure is
190 * not very useful. Currently, memory locking is not implemented.
193 Key *server_key; /* ephemeral server key */
194 Key *ssh1_host_key; /* ssh1 host key */
195 Key **host_keys; /* all private host keys */
198 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
202 * Flag indicating whether the RSA server key needs to be regenerated.
203 * Is set in the SIGALRM handler and cleared when the key is regenerated.
205 static volatile sig_atomic_t key_do_regen = 0;
207 /* This is set to true when a signal is received. */
208 static volatile sig_atomic_t received_sighup = 0;
209 static volatile sig_atomic_t received_sigterm = 0;
211 /* session identifier, used by RSA-auth */
212 u_char session_id[16];
215 u_char *session_id2 = NULL;
216 u_int session_id2_len = 0;
218 /* record remote hostname or ip */
219 u_int utmp_len = MAXHOSTNAMELEN;
221 /* options.max_startup sized array of fd ints */
222 int *startup_pipes = NULL;
223 int startup_pipe; /* in child */
225 /* variables used for privilege separation */
226 int use_privsep = -1;
227 struct monitor *pmonitor = NULL;
229 /* global authentication context */
230 Authctxt *the_authctxt = NULL;
232 /* sshd_config buffer */
235 /* message to be displayed after login */
238 /* Prototypes for various functions defined later in this file. */
239 void destroy_sensitive_data(void);
240 void demote_sensitive_data(void);
242 static void do_ssh1_kex(void);
243 static void do_ssh2_kex(void);
246 * Close all listening sockets
249 close_listen_socks(void)
253 for (i = 0; i < num_listen_socks; i++)
254 close(listen_socks[i]);
255 num_listen_socks = -1;
259 close_startup_pipes(void)
264 for (i = 0; i < options.max_startups; i++)
265 if (startup_pipes[i] != -1)
266 close(startup_pipes[i]);
270 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
271 * the effect is to reread the configuration file (and to regenerate
277 sighup_handler(int sig)
279 int save_errno = errno;
282 signal(SIGHUP, sighup_handler);
287 * Called from the main program after receiving SIGHUP.
288 * Restarts the server.
293 logit("Received SIGHUP; restarting.");
294 close_listen_socks();
295 close_startup_pipes();
296 execv(saved_argv[0], saved_argv);
297 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
303 * Generic signal handler for terminating signals in the master daemon.
307 sigterm_handler(int sig)
309 received_sigterm = sig;
313 * SIGCHLD handler. This is called whenever a child dies. This will then
314 * reap any zombies left by exited children.
318 main_sigchld_handler(int sig)
320 int save_errno = errno;
324 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
325 (pid < 0 && errno == EINTR))
328 signal(SIGCHLD, main_sigchld_handler);
333 * Signal handler for the alarm after the login grace period has expired.
337 grace_alarm_handler(int sig)
339 /* XXX no idea how fix this signal handler */
341 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
342 kill(pmonitor->m_pid, SIGALRM);
344 /* Log error and exit. */
345 fatal("Timeout before authentication for %s", get_remote_ipaddr());
349 * Signal handler for the key regeneration alarm. Note that this
350 * alarm only occurs in the daemon waiting for connections, and it does not
351 * do anything with the private key or random state before forking.
352 * Thus there should be no concurrency control/asynchronous execution
356 generate_ephemeral_server_key(void)
361 verbose("Generating %s%d bit RSA key.",
362 sensitive_data.server_key ? "new " : "", options.server_key_bits);
363 if (sensitive_data.server_key != NULL)
364 key_free(sensitive_data.server_key);
365 sensitive_data.server_key = key_generate(KEY_RSA1,
366 options.server_key_bits);
367 verbose("RSA key generation complete.");
369 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
372 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
380 key_regeneration_alarm(int sig)
382 int save_errno = errno;
384 signal(SIGALRM, SIG_DFL);
390 sshd_exchange_identification(int sock_in, int sock_out)
394 int remote_major, remote_minor;
397 char buf[256]; /* Must not be larger than remote_version. */
398 char remote_version[256]; /* Must be at least as big as buf. */
400 if ((options.protocol & SSH_PROTO_1) &&
401 (options.protocol & SSH_PROTO_2)) {
402 major = PROTOCOL_MAJOR_1;
404 } else if (options.protocol & SSH_PROTO_2) {
405 major = PROTOCOL_MAJOR_2;
406 minor = PROTOCOL_MINOR_2;
408 major = PROTOCOL_MAJOR_1;
409 minor = PROTOCOL_MINOR_1;
411 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
412 server_version_string = xstrdup(buf);
414 /* Send our protocol version identification. */
415 if (atomicio(vwrite, sock_out, server_version_string,
416 strlen(server_version_string))
417 != strlen(server_version_string)) {
418 logit("Could not write ident string to %s", get_remote_ipaddr());
422 /* Read other sides version identification. */
423 memset(buf, 0, sizeof(buf));
424 for (i = 0; i < sizeof(buf) - 1; i++) {
425 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
426 logit("Did not receive identification string from %s",
427 get_remote_ipaddr());
430 if (buf[i] == '\r') {
432 /* Kludge for F-Secure Macintosh < 1.0.2 */
434 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
438 if (buf[i] == '\n') {
443 buf[sizeof(buf) - 1] = 0;
444 client_version_string = xstrdup(buf);
447 * Check that the versions match. In future this might accept
448 * several versions and set appropriate flags to handle them.
450 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
451 &remote_major, &remote_minor, remote_version) != 3) {
452 s = "Protocol mismatch.\n";
453 (void) atomicio(vwrite, sock_out, s, strlen(s));
456 logit("Bad protocol version identification '%.100s' from %s",
457 client_version_string, get_remote_ipaddr());
460 debug("Client protocol version %d.%d; client software version %.100s",
461 remote_major, remote_minor, remote_version);
463 compat_datafellows(remote_version);
465 if (datafellows & SSH_BUG_PROBE) {
466 logit("probed from %s with %s. Don't panic.",
467 get_remote_ipaddr(), client_version_string);
471 if (datafellows & SSH_BUG_SCANNER) {
472 logit("scanned from %s with %s. Don't panic.",
473 get_remote_ipaddr(), client_version_string);
478 switch (remote_major) {
480 if (remote_minor == 99) {
481 if (options.protocol & SSH_PROTO_2)
487 if (!(options.protocol & SSH_PROTO_1)) {
491 if (remote_minor < 3) {
492 packet_disconnect("Your ssh version is too old and "
493 "is no longer supported. Please install a newer version.");
494 } else if (remote_minor == 3) {
495 /* note that this disables agent-forwarding */
500 if (options.protocol & SSH_PROTO_2) {
509 chop(server_version_string);
510 debug("Local version string %.200s", server_version_string);
513 s = "Protocol major versions differ.\n";
514 (void) atomicio(vwrite, sock_out, s, strlen(s));
517 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
519 server_version_string, client_version_string);
524 /* Destroy the host and server keys. They will no longer be needed. */
526 destroy_sensitive_data(void)
530 if (sensitive_data.server_key) {
531 key_free(sensitive_data.server_key);
532 sensitive_data.server_key = NULL;
534 for (i = 0; i < options.num_host_key_files; i++) {
535 if (sensitive_data.host_keys[i]) {
536 key_free(sensitive_data.host_keys[i]);
537 sensitive_data.host_keys[i] = NULL;
540 sensitive_data.ssh1_host_key = NULL;
541 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
544 /* Demote private to public keys for network child */
546 demote_sensitive_data(void)
551 if (sensitive_data.server_key) {
552 tmp = key_demote(sensitive_data.server_key);
553 key_free(sensitive_data.server_key);
554 sensitive_data.server_key = tmp;
557 for (i = 0; i < options.num_host_key_files; i++) {
558 if (sensitive_data.host_keys[i]) {
559 tmp = key_demote(sensitive_data.host_keys[i]);
560 key_free(sensitive_data.host_keys[i]);
561 sensitive_data.host_keys[i] = tmp;
562 if (tmp->type == KEY_RSA1)
563 sensitive_data.ssh1_host_key = tmp;
567 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
571 privsep_preauth_child(void)
578 /* Enable challenge-response authentication for privilege separation */
579 privsep_challenge_enable();
581 for (i = 0; i < 256; i++)
582 rnd[i] = arc4random();
583 RAND_seed(rnd, sizeof(rnd));
585 /* Demote the private keys to public keys. */
586 demote_sensitive_data();
588 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
589 fatal("Privilege separation user %s does not exist",
591 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
594 /* Change our root directory */
595 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
596 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
598 if (chdir("/") == -1)
599 fatal("chdir(\"/\"): %s", strerror(errno));
601 /* Drop our privileges */
602 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
605 /* XXX not ready, too heavy after chroot */
606 do_setusercontext(pw);
608 gidset[0] = pw->pw_gid;
609 if (setgroups(1, gidset) < 0)
610 fatal("setgroups: %.100s", strerror(errno));
611 permanently_set_uid(pw);
616 privsep_preauth(Authctxt *authctxt)
621 /* Set up unprivileged child process to deal with network data */
622 pmonitor = monitor_init();
623 /* Store a pointer to the kex for later rekeying */
624 pmonitor->m_pkex = &xxx_kex;
628 fatal("fork of unprivileged child failed");
629 } else if (pid != 0) {
630 debug2("Network child is on pid %ld", (long)pid);
632 close(pmonitor->m_recvfd);
633 pmonitor->m_pid = pid;
634 monitor_child_preauth(authctxt, pmonitor);
635 close(pmonitor->m_sendfd);
638 monitor_sync(pmonitor);
640 /* Wait for the child's exit status */
641 while (waitpid(pid, &status, 0) < 0)
648 close(pmonitor->m_sendfd);
650 /* Demote the child */
651 if (getuid() == 0 || geteuid() == 0)
652 privsep_preauth_child();
653 setproctitle("%s", "[net]");
659 privsep_postauth(Authctxt *authctxt)
661 #ifdef DISABLE_FD_PASSING
664 if (authctxt->pw->pw_uid == 0 || options.use_login) {
666 /* File descriptor passing is broken or root login */
671 /* New socket pair */
672 monitor_reinit(pmonitor);
674 pmonitor->m_pid = fork();
675 if (pmonitor->m_pid == -1)
676 fatal("fork of unprivileged child failed");
677 else if (pmonitor->m_pid != 0) {
678 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
679 close(pmonitor->m_recvfd);
680 buffer_clear(&loginmsg);
681 monitor_child_postauth(pmonitor);
687 close(pmonitor->m_sendfd);
689 /* Demote the private keys to public keys. */
690 demote_sensitive_data();
692 /* Drop privileges */
693 do_setusercontext(authctxt->pw);
696 /* It is safe now to apply the key state */
697 monitor_apply_keystate(pmonitor);
700 * Tell the packet layer that authentication was successful, since
701 * this information is not part of the key state.
703 packet_set_authenticated();
707 list_hostkey_types(void)
715 for (i = 0; i < options.num_host_key_files; i++) {
716 Key *key = sensitive_data.host_keys[i];
722 if (buffer_len(&b) > 0)
723 buffer_append(&b, ",", 1);
724 p = key_ssh_name(key);
725 buffer_append(&b, p, strlen(p));
729 buffer_append(&b, "\0", 1);
730 ret = xstrdup(buffer_ptr(&b));
732 debug("list_hostkey_types: %s", ret);
737 get_hostkey_by_type(int type)
741 for (i = 0; i < options.num_host_key_files; i++) {
742 Key *key = sensitive_data.host_keys[i];
743 if (key != NULL && key->type == type)
750 get_hostkey_by_index(int ind)
752 if (ind < 0 || ind >= options.num_host_key_files)
754 return (sensitive_data.host_keys[ind]);
758 get_hostkey_index(Key *key)
762 for (i = 0; i < options.num_host_key_files; i++) {
763 if (key == sensitive_data.host_keys[i])
770 * returns 1 if connection should be dropped, 0 otherwise.
771 * dropping starts at connection #max_startups_begin with a probability
772 * of (max_startups_rate/100). the probability increases linearly until
773 * all connections are dropped for startups > max_startups
776 drop_connection(int startups)
780 if (startups < options.max_startups_begin)
782 if (startups >= options.max_startups)
784 if (options.max_startups_rate == 100)
787 p = 100 - options.max_startups_rate;
788 p *= startups - options.max_startups_begin;
789 p /= options.max_startups - options.max_startups_begin;
790 p += options.max_startups_rate;
791 r = arc4random() % 100;
793 debug("drop_connection: p %d, r %d", p, r);
794 return (r < p) ? 1 : 0;
800 fprintf(stderr, "%s, %s\n",
801 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
803 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
804 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
810 send_rexec_state(int fd, Buffer *conf)
814 debug3("%s: entering fd = %d config len %d", __func__, fd,
818 * Protocol from reexec master to child:
819 * string configuration
820 * u_int ephemeral_key_follows
821 * bignum e (only if ephemeral_key_follows == 1)
827 * string rngseed (only if OpenSSL is not self-seeded)
830 buffer_put_cstring(&m, buffer_ptr(conf));
832 if (sensitive_data.server_key != NULL &&
833 sensitive_data.server_key->type == KEY_RSA1) {
834 buffer_put_int(&m, 1);
835 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
836 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
837 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
838 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
839 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
840 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
842 buffer_put_int(&m, 0);
844 #ifndef OPENSSL_PRNG_ONLY
845 rexec_send_rng_seed(&m);
848 if (ssh_msg_send(fd, 0, &m) == -1)
849 fatal("%s: ssh_msg_send failed", __func__);
853 debug3("%s: done", __func__);
857 recv_rexec_state(int fd, Buffer *conf)
863 debug3("%s: entering fd = %d", __func__, fd);
867 if (ssh_msg_recv(fd, &m) == -1)
868 fatal("%s: ssh_msg_recv failed", __func__);
869 if (buffer_get_char(&m) != 0)
870 fatal("%s: rexec version mismatch", __func__);
872 cp = buffer_get_string(&m, &len);
874 buffer_append(conf, cp, len + 1);
877 if (buffer_get_int(&m)) {
878 if (sensitive_data.server_key != NULL)
879 key_free(sensitive_data.server_key);
880 sensitive_data.server_key = key_new_private(KEY_RSA1);
881 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
882 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
883 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
884 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
885 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
886 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
887 rsa_generate_additional_parameters(
888 sensitive_data.server_key->rsa);
891 #ifndef OPENSSL_PRNG_ONLY
892 rexec_recv_rng_seed(&m);
897 debug3("%s: done", __func__);
901 * Main program for the daemon.
904 main(int ac, char **av)
908 int opt, j, i, on = 1;
909 int sock_in = -1, sock_out = -1, newsock = -1;
913 struct sockaddr_storage from;
914 const char *remote_ip;
918 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
920 int listen_sock, maxfd;
921 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
925 int ret, key_used = 0;
927 #ifdef HAVE_SECUREWARE
928 (void)set_auth_parameters(ac, av);
930 __progname = ssh_get_progname(av[0]);
933 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
936 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
937 for (i = 0; i < ac; i++)
938 saved_argv[i] = xstrdup(av[i]);
939 saved_argv[i] = NULL;
941 #ifndef HAVE_SETPROCTITLE
942 /* Prepare for later setproctitle emulation */
943 compat_init_setproctitle(ac, av);
947 if (geteuid() == 0 && setgroups(0, NULL) == -1)
948 debug("setgroups(): %.200s", strerror(errno));
950 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
953 /* Initialize configuration options to their default values. */
954 initialize_server_options(&options);
956 /* Parse command-line arguments. */
957 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
960 options.address_family = AF_INET;
963 options.address_family = AF_INET6;
966 config_file_name = optarg;
969 if (debug_flag == 0) {
971 options.log_level = SYSLOG_LEVEL_DEBUG1;
972 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
995 options.log_level = SYSLOG_LEVEL_QUIET;
998 options.server_key_bits = (int)strtonum(optarg, 256,
1002 options.ports_from_cmdline = 1;
1003 if (options.num_ports >= MAX_PORTS) {
1004 fprintf(stderr, "too many ports.\n");
1007 options.ports[options.num_ports++] = a2port(optarg);
1008 if (options.ports[options.num_ports-1] == 0) {
1009 fprintf(stderr, "Bad port number.\n");
1014 if ((options.login_grace_time = convtime(optarg)) == -1) {
1015 fprintf(stderr, "Invalid login grace time.\n");
1020 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1021 fprintf(stderr, "Invalid key regeneration interval.\n");
1026 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1027 fprintf(stderr, "too many host keys.\n");
1030 options.host_key_files[options.num_host_key_files++] = optarg;
1036 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1037 if (utmp_len > MAXHOSTNAMELEN) {
1038 fprintf(stderr, "Invalid utmp length.\n");
1043 line = xstrdup(optarg);
1044 if (process_server_config_line(&options, line,
1045 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1055 if (rexeced_flag || inetd_flag)
1057 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1058 fatal("sshd re-exec requires execution with an absolute path");
1060 closefrom(REEXEC_MIN_FREE_FD);
1062 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1064 SSLeay_add_all_algorithms();
1067 * Force logging to stderr until we have loaded the private host
1068 * key (unless started from inetd)
1070 log_init(__progname,
1071 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1072 SYSLOG_LEVEL_INFO : options.log_level,
1073 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1074 SYSLOG_FACILITY_AUTH : options.log_facility,
1075 log_stderr || !inetd_flag);
1078 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1079 * root's environment
1081 if (getenv("KRB5CCNAME") != NULL)
1082 unsetenv("KRB5CCNAME");
1085 /* Cray can define user privs drop all privs now!
1086 * Not needed on PRIV_SU systems!
1091 sensitive_data.server_key = NULL;
1092 sensitive_data.ssh1_host_key = NULL;
1093 sensitive_data.have_ssh1_key = 0;
1094 sensitive_data.have_ssh2_key = 0;
1096 /* Fetch our configuration */
1099 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1101 load_server_config(config_file_name, &cfg);
1103 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1104 &cfg, NULL, NULL, NULL);
1108 /* Fill in default values for those options not explicitly set. */
1109 fill_default_server_options(&options);
1111 /* set default channel AF */
1112 channel_set_af(options.address_family);
1114 /* Check that there are no remaining arguments. */
1116 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1120 debug("sshd version %.100s", SSH_RELEASE);
1122 /* load private host keys */
1123 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1125 for (i = 0; i < options.num_host_key_files; i++)
1126 sensitive_data.host_keys[i] = NULL;
1128 for (i = 0; i < options.num_host_key_files; i++) {
1129 key = key_load_private(options.host_key_files[i], "", NULL);
1130 sensitive_data.host_keys[i] = key;
1132 error("Could not load host key: %s",
1133 options.host_key_files[i]);
1134 sensitive_data.host_keys[i] = NULL;
1137 switch (key->type) {
1139 sensitive_data.ssh1_host_key = key;
1140 sensitive_data.have_ssh1_key = 1;
1144 sensitive_data.have_ssh2_key = 1;
1147 debug("private host key: #%d type %d %s", i, key->type,
1150 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1151 logit("Disabling protocol version 1. Could not load host key");
1152 options.protocol &= ~SSH_PROTO_1;
1154 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1155 logit("Disabling protocol version 2. Could not load host key");
1156 options.protocol &= ~SSH_PROTO_2;
1158 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1159 logit("sshd: no hostkeys available -- exiting.");
1163 /* Check certain values for sanity. */
1164 if (options.protocol & SSH_PROTO_1) {
1165 if (options.server_key_bits < 512 ||
1166 options.server_key_bits > 32768) {
1167 fprintf(stderr, "Bad server key size.\n");
1171 * Check that server and host key lengths differ sufficiently. This
1172 * is necessary to make double encryption work with rsaref. Oh, I
1173 * hate software patents. I dont know if this can go? Niels
1175 if (options.server_key_bits >
1176 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1177 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1178 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1179 SSH_KEY_BITS_RESERVED) {
1180 options.server_key_bits =
1181 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1182 SSH_KEY_BITS_RESERVED;
1183 debug("Forcing server key to %d bits to make it differ from host key.",
1184 options.server_key_bits);
1191 if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1192 fatal("Privilege separation user %s does not exist",
1194 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1195 (S_ISDIR(st.st_mode) == 0))
1196 fatal("Missing privilege separation directory: %s",
1197 _PATH_PRIVSEP_CHROOT_DIR);
1200 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1201 (st.st_uid != getuid () ||
1202 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1204 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1206 fatal("%s must be owned by root and not group or "
1207 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1210 /* Configuration looks good, so exit if in test mode. */
1215 * Clear out any supplemental groups we may have inherited. This
1216 * prevents inadvertent creation of files with bad modes (in the
1217 * portable version at least, it's certainly possible for PAM
1218 * to create a file, and we can't control the code in every
1219 * module which might be used).
1221 if (setgroups(0, NULL) < 0)
1222 debug("setgroups() failed: %.200s", strerror(errno));
1225 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1226 for (i = 0; i < rexec_argc; i++) {
1227 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1228 rexec_argv[i] = saved_argv[i];
1230 rexec_argv[rexec_argc] = "-R";
1231 rexec_argv[rexec_argc + 1] = NULL;
1234 /* Initialize the log (it is reinitialized below in case we forked). */
1235 if (debug_flag && (!inetd_flag || rexeced_flag))
1237 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1240 * If not in debugging mode, and not started from inetd, disconnect
1241 * from the controlling terminal, and fork. The original process
1244 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1247 #endif /* TIOCNOTTY */
1248 if (daemon(0, 0) < 0)
1249 fatal("daemon() failed: %.200s", strerror(errno));
1251 /* Disconnect from the controlling tty. */
1253 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1255 (void) ioctl(fd, TIOCNOTTY, NULL);
1258 #endif /* TIOCNOTTY */
1260 /* Reinitialize the log (because of the fork above). */
1261 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1263 /* Initialize the random number generator. */
1266 /* Chdir to the root directory so that the current disk can be
1267 unmounted if desired. */
1270 /* ignore SIGPIPE */
1271 signal(SIGPIPE, SIG_IGN);
1273 /* Start listening for a socket, unless started from inetd. */
1279 close(REEXEC_CONFIG_PASS_FD);
1280 sock_in = sock_out = dup(STDIN_FILENO);
1282 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1283 close(REEXEC_STARTUP_PIPE_FD);
1286 sock_in = dup(STDIN_FILENO);
1287 sock_out = dup(STDOUT_FILENO);
1290 * We intentionally do not close the descriptors 0, 1, and 2
1291 * as our code for setting the descriptors won't work if
1292 * ttyfd happens to be one of those.
1294 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1295 dup2(fd, STDIN_FILENO);
1296 dup2(fd, STDOUT_FILENO);
1297 if (fd > STDOUT_FILENO)
1300 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1301 if ((options.protocol & SSH_PROTO_1) &&
1302 sensitive_data.server_key == NULL)
1303 generate_ephemeral_server_key();
1305 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1306 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1308 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1309 fatal("Too many listen sockets. "
1310 "Enlarge MAX_LISTEN_SOCKS");
1311 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1312 ntop, sizeof(ntop), strport, sizeof(strport),
1313 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1314 error("getnameinfo failed: %.100s",
1315 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1319 /* Create socket for listening. */
1320 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1322 if (listen_sock < 0) {
1323 /* kernel may not support ipv6 */
1324 verbose("socket: %.100s", strerror(errno));
1327 if (set_nonblock(listen_sock) == -1) {
1332 * Set socket options.
1333 * Allow local port reuse in TIME_WAIT.
1335 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1336 &on, sizeof(on)) == -1)
1337 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1339 debug("Bind to port %s on %s.", strport, ntop);
1341 /* Bind the socket to the desired port. */
1342 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1344 error("Bind to port %s on %s failed: %.200s.",
1345 strport, ntop, strerror(errno));
1349 listen_socks[num_listen_socks] = listen_sock;
1352 /* Start listening on the port. */
1353 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1354 fatal("listen on [%s]:%s: %.100s",
1355 ntop, strport, strerror(errno));
1356 logit("Server listening on %s port %s.", ntop, strport);
1358 freeaddrinfo(options.listen_addrs);
1360 if (!num_listen_socks)
1361 fatal("Cannot bind any address.");
1363 if (options.protocol & SSH_PROTO_1)
1364 generate_ephemeral_server_key();
1367 * Arrange to restart on SIGHUP. The handler needs
1370 signal(SIGHUP, sighup_handler);
1372 signal(SIGTERM, sigterm_handler);
1373 signal(SIGQUIT, sigterm_handler);
1375 /* Arrange SIGCHLD to be caught. */
1376 signal(SIGCHLD, main_sigchld_handler);
1378 /* Write out the pid file after the sigterm handler is setup */
1381 * Record our pid in /var/run/sshd.pid to make it
1382 * easier to kill the correct sshd. We don't want to
1383 * do this before the bind above because the bind will
1384 * fail if there already is a daemon, and this will
1385 * overwrite any old pid in the file.
1387 f = fopen(options.pid_file, "wb");
1389 error("Couldn't create pid file \"%s\": %s",
1390 options.pid_file, strerror(errno));
1392 fprintf(f, "%ld\n", (long) getpid());
1397 /* setup fd set for listen */
1400 for (i = 0; i < num_listen_socks; i++)
1401 if (listen_socks[i] > maxfd)
1402 maxfd = listen_socks[i];
1403 /* pipes connected to unauthenticated childs */
1404 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1405 for (i = 0; i < options.max_startups; i++)
1406 startup_pipes[i] = -1;
1409 * Stay listening for connections until the system crashes or
1410 * the daemon is killed with a signal.
1413 if (received_sighup)
1417 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1420 for (i = 0; i < num_listen_socks; i++)
1421 FD_SET(listen_socks[i], fdset);
1422 for (i = 0; i < options.max_startups; i++)
1423 if (startup_pipes[i] != -1)
1424 FD_SET(startup_pipes[i], fdset);
1426 /* Wait in select until there is a connection. */
1427 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1428 if (ret < 0 && errno != EINTR)
1429 error("select: %.100s", strerror(errno));
1430 if (received_sigterm) {
1431 logit("Received signal %d; terminating.",
1432 (int) received_sigterm);
1433 close_listen_socks();
1434 unlink(options.pid_file);
1437 if (key_used && key_do_regen) {
1438 generate_ephemeral_server_key();
1445 for (i = 0; i < options.max_startups; i++)
1446 if (startup_pipes[i] != -1 &&
1447 FD_ISSET(startup_pipes[i], fdset)) {
1449 * the read end of the pipe is ready
1450 * if the child has closed the pipe
1451 * after successful authentication
1452 * or if the child has died
1454 close(startup_pipes[i]);
1455 startup_pipes[i] = -1;
1458 for (i = 0; i < num_listen_socks; i++) {
1459 if (!FD_ISSET(listen_socks[i], fdset))
1461 fromlen = sizeof(from);
1462 newsock = accept(listen_socks[i],
1463 (struct sockaddr *)&from, &fromlen);
1465 if (errno != EINTR && errno != EWOULDBLOCK)
1466 error("accept: %.100s", strerror(errno));
1469 if (unset_nonblock(newsock) == -1) {
1473 if (drop_connection(startups) == 1) {
1474 debug("drop connection #%d", startups);
1478 if (pipe(startup_p) == -1) {
1483 if (rexec_flag && socketpair(AF_UNIX,
1484 SOCK_STREAM, 0, config_s) == -1) {
1485 error("reexec socketpair: %s",
1488 close(startup_p[0]);
1489 close(startup_p[1]);
1493 for (j = 0; j < options.max_startups; j++)
1494 if (startup_pipes[j] == -1) {
1495 startup_pipes[j] = startup_p[0];
1496 if (maxfd < startup_p[0])
1497 maxfd = startup_p[0];
1503 * Got connection. Fork a child to handle it, unless
1504 * we are in debugging mode.
1508 * In debugging mode. Close the listening
1509 * socket, and start processing the
1510 * connection without forking.
1512 debug("Server will not fork when running in debugging mode.");
1513 close_listen_socks();
1516 close(startup_p[0]);
1517 close(startup_p[1]);
1521 send_rexec_state(config_s[0],
1528 * Normal production daemon. Fork, and have
1529 * the child process the connection. The
1530 * parent continues listening.
1532 if ((pid = fork()) == 0) {
1534 * Child. Close the listening and
1535 * max_startup sockets. Start using
1536 * the accepted socket. Reinitialize
1537 * logging (since our pid has changed).
1538 * We break out of the loop to handle
1541 startup_pipe = startup_p[1];
1542 close_startup_pipes();
1543 close_listen_socks();
1546 log_init(__progname,
1548 options.log_facility,
1556 /* Parent. Stay in the loop. */
1558 error("fork: %.100s", strerror(errno));
1560 debug("Forked child %ld.", (long)pid);
1562 close(startup_p[1]);
1565 send_rexec_state(config_s[0], &cfg);
1571 * Mark that the key has been used (it
1572 * was "given" to the child).
1574 if ((options.protocol & SSH_PROTO_1) &&
1576 /* Schedule server key regeneration alarm. */
1577 signal(SIGALRM, key_regeneration_alarm);
1578 alarm(options.key_regeneration_time);
1585 /* child process check (or debug mode) */
1586 if (num_listen_socks < 0)
1591 /* This is the child processing a new connection. */
1592 setproctitle("%s", "[accepted]");
1595 * Create a new session and process group since the 4.4BSD
1596 * setlogin() affects the entire process group. We don't
1597 * want the child to be able to affect the parent.
1599 #if !defined(SSHD_ACQUIRES_CTTY)
1601 * If setsid is called, on some platforms sshd will later acquire a
1602 * controlling terminal which will result in "could not set
1603 * controlling tty" errors.
1605 if (!debug_flag && !inetd_flag && setsid() < 0)
1606 error("setsid: %.100s", strerror(errno));
1612 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1613 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1614 dup2(newsock, STDIN_FILENO);
1615 dup2(STDIN_FILENO, STDOUT_FILENO);
1616 if (startup_pipe == -1)
1617 close(REEXEC_STARTUP_PIPE_FD);
1619 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1621 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1623 if (startup_pipe != -1)
1624 close(startup_pipe);
1626 execv(rexec_argv[0], rexec_argv);
1628 /* Reexec has failed, fall back and continue */
1629 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1630 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1631 log_init(__progname, options.log_level,
1632 options.log_facility, log_stderr);
1635 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1637 close(REEXEC_CONFIG_PASS_FD);
1638 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1639 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1640 dup2(fd, STDIN_FILENO);
1641 dup2(fd, STDOUT_FILENO);
1642 if (fd > STDERR_FILENO)
1645 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1646 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1650 * Disable the key regeneration alarm. We will not regenerate the
1651 * key since we are no longer in a position to give it to anyone. We
1652 * will not restart on SIGHUP since it no longer makes sense.
1655 signal(SIGALRM, SIG_DFL);
1656 signal(SIGHUP, SIG_DFL);
1657 signal(SIGTERM, SIG_DFL);
1658 signal(SIGQUIT, SIG_DFL);
1659 signal(SIGCHLD, SIG_DFL);
1660 signal(SIGINT, SIG_DFL);
1663 * Register our connection. This turns encryption off because we do
1666 packet_set_connection(sock_in, sock_out);
1667 packet_set_server();
1669 /* Set SO_KEEPALIVE if requested. */
1670 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1671 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1672 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1674 if ((remote_port = get_remote_port()) < 0) {
1675 debug("get_remote_port failed");
1680 * We use get_canonical_hostname with usedns = 0 instead of
1681 * get_remote_ipaddr here so IP options will be checked.
1683 (void) get_canonical_hostname(0);
1685 * The rest of the code depends on the fact that
1686 * get_remote_ipaddr() caches the remote ip, even if
1687 * the socket goes away.
1689 remote_ip = get_remote_ipaddr();
1691 #ifdef SSH_AUDIT_EVENTS
1692 audit_connection_from(remote_ip, remote_port);
1695 /* Check whether logins are denied from this host. */
1696 if (packet_connection_is_on_socket()) {
1697 struct request_info req;
1699 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1702 if (!hosts_access(&req)) {
1703 debug("Connection refused by tcp wrapper");
1706 fatal("libwrap refuse returns");
1709 #endif /* LIBWRAP */
1711 /* Log the connection. */
1712 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1715 * We don't want to listen forever unless the other side
1716 * successfully authenticates itself. So we set up an alarm which is
1717 * cleared after successful authentication. A limit of zero
1718 * indicates no limit. Note that we don't set the alarm in debugging
1719 * mode; it is just annoying to have the server exit just when you
1720 * are about to discover the bug.
1722 signal(SIGALRM, grace_alarm_handler);
1724 alarm(options.login_grace_time);
1726 sshd_exchange_identification(sock_in, sock_out);
1728 packet_set_nonblocking();
1730 /* allocate authentication context */
1731 authctxt = xcalloc(1, sizeof(*authctxt));
1733 authctxt->loginmsg = &loginmsg;
1735 /* XXX global for cleanup, access from other modules */
1736 the_authctxt = authctxt;
1738 /* prepare buffer to collect messages to display to user after login */
1739 buffer_init(&loginmsg);
1742 if (privsep_preauth(authctxt) == 1)
1745 /* perform the key exchange */
1746 /* authenticate user and start session */
1749 do_authentication2(authctxt);
1752 do_authentication(authctxt);
1755 * If we use privilege separation, the unprivileged child transfers
1756 * the current keystate and exits
1759 mm_send_keystate(pmonitor);
1765 * Cancel the alarm we set to limit the time taken for
1769 signal(SIGALRM, SIG_DFL);
1770 if (startup_pipe != -1) {
1771 close(startup_pipe);
1775 #ifdef SSH_AUDIT_EVENTS
1776 audit_event(SSH_AUTH_SUCCESS);
1780 * In privilege separation, we fork another child and prepare
1781 * file descriptor passing.
1784 privsep_postauth(authctxt);
1785 /* the monitor process [priv] will not return */
1787 destroy_sensitive_data();
1790 /* Start session. */
1791 do_authenticated(authctxt);
1793 /* The connection has been terminated. */
1794 verbose("Closing connection to %.100s", remote_ip);
1797 if (options.use_pam)
1799 #endif /* USE_PAM */
1801 #ifdef SSH_AUDIT_EVENTS
1802 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1814 * Decrypt session_key_int using our private server key and private host key
1815 * (key with larger modulus first).
1818 ssh1_session_key(BIGNUM *session_key_int)
1822 if (BN_cmp(sensitive_data.server_key->rsa->n,
1823 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1824 /* Server key has bigger modulus. */
1825 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1826 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1827 SSH_KEY_BITS_RESERVED) {
1828 fatal("do_connection: %s: "
1829 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1830 get_remote_ipaddr(),
1831 BN_num_bits(sensitive_data.server_key->rsa->n),
1832 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1833 SSH_KEY_BITS_RESERVED);
1835 if (rsa_private_decrypt(session_key_int, session_key_int,
1836 sensitive_data.server_key->rsa) <= 0)
1838 if (rsa_private_decrypt(session_key_int, session_key_int,
1839 sensitive_data.ssh1_host_key->rsa) <= 0)
1842 /* Host key has bigger modulus (or they are equal). */
1843 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1844 BN_num_bits(sensitive_data.server_key->rsa->n) +
1845 SSH_KEY_BITS_RESERVED) {
1846 fatal("do_connection: %s: "
1847 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1848 get_remote_ipaddr(),
1849 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1850 BN_num_bits(sensitive_data.server_key->rsa->n),
1851 SSH_KEY_BITS_RESERVED);
1853 if (rsa_private_decrypt(session_key_int, session_key_int,
1854 sensitive_data.ssh1_host_key->rsa) < 0)
1856 if (rsa_private_decrypt(session_key_int, session_key_int,
1857 sensitive_data.server_key->rsa) < 0)
1870 BIGNUM *session_key_int;
1871 u_char session_key[SSH_SESSION_KEY_LENGTH];
1873 u_int cipher_type, auth_mask, protocol_flags;
1877 * Generate check bytes that the client must send back in the user
1878 * packet in order for it to be accepted; this is used to defy ip
1879 * spoofing attacks. Note that this only works against somebody
1880 * doing IP spoofing from a remote machine; any machine on the local
1881 * network can still see outgoing packets and catch the random
1882 * cookie. This only affects rhosts authentication, and this is one
1883 * of the reasons why it is inherently insecure.
1885 for (i = 0; i < 8; i++) {
1888 cookie[i] = rnd & 0xff;
1893 * Send our public key. We include in the packet 64 bits of random
1894 * data that must be matched in the reply in order to prevent IP
1897 packet_start(SSH_SMSG_PUBLIC_KEY);
1898 for (i = 0; i < 8; i++)
1899 packet_put_char(cookie[i]);
1901 /* Store our public server RSA key. */
1902 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1903 packet_put_bignum(sensitive_data.server_key->rsa->e);
1904 packet_put_bignum(sensitive_data.server_key->rsa->n);
1906 /* Store our public host RSA key. */
1907 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1908 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1909 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1911 /* Put protocol flags. */
1912 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1914 /* Declare which ciphers we support. */
1915 packet_put_int(cipher_mask_ssh1(0));
1917 /* Declare supported authentication types. */
1919 if (options.rhosts_rsa_authentication)
1920 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1921 if (options.rsa_authentication)
1922 auth_mask |= 1 << SSH_AUTH_RSA;
1923 if (options.challenge_response_authentication == 1)
1924 auth_mask |= 1 << SSH_AUTH_TIS;
1925 if (options.password_authentication)
1926 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1927 packet_put_int(auth_mask);
1929 /* Send the packet and wait for it to be sent. */
1931 packet_write_wait();
1933 debug("Sent %d bit server key and %d bit host key.",
1934 BN_num_bits(sensitive_data.server_key->rsa->n),
1935 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1937 /* Read clients reply (cipher type and session key). */
1938 packet_read_expect(SSH_CMSG_SESSION_KEY);
1940 /* Get cipher type and check whether we accept this. */
1941 cipher_type = packet_get_char();
1943 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1944 packet_disconnect("Warning: client selects unsupported cipher.");
1946 /* Get check bytes from the packet. These must match those we
1947 sent earlier with the public key packet. */
1948 for (i = 0; i < 8; i++)
1949 if (cookie[i] != packet_get_char())
1950 packet_disconnect("IP Spoofing check bytes do not match.");
1952 debug("Encryption type: %.200s", cipher_name(cipher_type));
1954 /* Get the encrypted integer. */
1955 if ((session_key_int = BN_new()) == NULL)
1956 fatal("do_ssh1_kex: BN_new failed");
1957 packet_get_bignum(session_key_int);
1959 protocol_flags = packet_get_int();
1960 packet_set_protocol_flags(protocol_flags);
1963 /* Decrypt session_key_int using host/server keys */
1964 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1967 * Extract session key from the decrypted integer. The key is in the
1968 * least significant 256 bits of the integer; the first byte of the
1969 * key is in the highest bits.
1972 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1973 len = BN_num_bytes(session_key_int);
1974 if (len < 0 || (u_int)len > sizeof(session_key)) {
1975 error("do_connection: bad session key len from %s: "
1976 "session_key_int %d > sizeof(session_key) %lu",
1977 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1980 memset(session_key, 0, sizeof(session_key));
1981 BN_bn2bin(session_key_int,
1982 session_key + sizeof(session_key) - len);
1984 derive_ssh1_session_id(
1985 sensitive_data.ssh1_host_key->rsa->n,
1986 sensitive_data.server_key->rsa->n,
1987 cookie, session_id);
1989 * Xor the first 16 bytes of the session key with the
1992 for (i = 0; i < 16; i++)
1993 session_key[i] ^= session_id[i];
1997 int bytes = BN_num_bytes(session_key_int);
1998 u_char *buf = xmalloc(bytes);
2001 logit("do_connection: generating a fake encryption key");
2002 BN_bn2bin(session_key_int, buf);
2004 MD5_Update(&md, buf, bytes);
2005 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2006 MD5_Final(session_key, &md);
2008 MD5_Update(&md, session_key, 16);
2009 MD5_Update(&md, buf, bytes);
2010 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2011 MD5_Final(session_key + 16, &md);
2012 memset(buf, 0, bytes);
2014 for (i = 0; i < 16; i++)
2015 session_id[i] = session_key[i] ^ session_key[i + 16];
2017 /* Destroy the private and public keys. No longer. */
2018 destroy_sensitive_data();
2021 mm_ssh1_session_id(session_id);
2023 /* Destroy the decrypted integer. It is no longer needed. */
2024 BN_clear_free(session_key_int);
2026 /* Set the session key. From this on all communications will be encrypted. */
2027 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2029 /* Destroy our copy of the session key. It is no longer needed. */
2030 memset(session_key, 0, sizeof(session_key));
2032 debug("Received session key; encryption turned on.");
2034 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2035 packet_start(SSH_SMSG_SUCCESS);
2037 packet_write_wait();
2041 * SSH2 key exchange: diffie-hellman-group1-sha1
2048 if (options.ciphers != NULL) {
2049 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2050 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2052 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2053 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2054 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2055 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2057 if (options.macs != NULL) {
2058 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2059 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2061 if (options.compression == COMP_NONE) {
2062 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2063 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2064 } else if (options.compression == COMP_DELAYED) {
2065 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2066 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2069 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2071 /* start key exchange */
2072 kex = kex_setup(myproposal);
2073 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2074 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2075 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2076 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2078 kex->client_version_string=client_version_string;
2079 kex->server_version_string=server_version_string;
2080 kex->load_host_key=&get_hostkey_by_type;
2081 kex->host_key_index=&get_hostkey_index;
2085 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2087 session_id2 = kex->session_id;
2088 session_id2_len = kex->session_id_len;
2091 /* send 1st encrypted/maced/compressed message */
2092 packet_start(SSH2_MSG_IGNORE);
2093 packet_put_cstring("markus");
2095 packet_write_wait();
2100 /* server specific fatal cleanup */
2105 do_cleanup(the_authctxt);
2106 #ifdef SSH_AUDIT_EVENTS
2107 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2108 if (!use_privsep || mm_is_monitor())
2109 audit_event(SSH_CONNECTION_ABANDON);