1 /* $OpenBSD: sshd.c,v 1.338 2006/07/12 22:28:52 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)
67 #include <openssl/dh.h>
68 #include <openssl/bn.h>
69 #include <openssl/md5.h>
70 #include <openssl/rand.h>
71 #ifdef HAVE_SECUREWARE
72 #include <sys/security.h>
93 #include "myproposal.h"
95 #include "pathnames.h"
101 #include "dispatch.h"
102 #include "channels.h"
104 #include "monitor_mm.h"
106 #include "monitor_wrap.h"
107 #include "monitor_fdpass.h"
113 int allow_severity = LOG_INFO;
114 int deny_severity = LOG_WARNING;
122 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
123 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
124 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
125 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
127 extern char *__progname;
129 /* Server configuration options. */
130 ServerOptions options;
132 /* Name of the server configuration file. */
133 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
136 * Debug mode flag. This can be set on the command line. If debug
137 * mode is enabled, extra debugging output will be sent to the system
138 * log, the daemon will not go to background, and will exit after processing
139 * the first connection.
143 /* Flag indicating that the daemon should only test the configuration and keys. */
146 /* Flag indicating that the daemon is being started from inetd. */
149 /* Flag indicating that sshd should not detach and become a daemon. */
150 int no_daemon_flag = 0;
152 /* debug goes to stderr unless inetd_flag is set */
155 /* Saved arguments to main(). */
160 int rexeced_flag = 0;
166 * The sockets that the server is listening; this is used in the SIGHUP
169 #define MAX_LISTEN_SOCKS 16
170 int listen_socks[MAX_LISTEN_SOCKS];
171 int num_listen_socks = 0;
174 * the client's version string, passed by sshd2 in compat mode. if != NULL,
175 * sshd will skip the version-number exchange
177 char *client_version_string = NULL;
178 char *server_version_string = NULL;
180 /* for rekeying XXX fixme */
184 * Any really sensitive data in the application is contained in this
185 * structure. The idea is that this structure could be locked into memory so
186 * that the pages do not get written into swap. However, there are some
187 * problems. The private key contains BIGNUMs, and we do not (in principle)
188 * have access to the internals of them, and locking just the structure is
189 * not very useful. Currently, memory locking is not implemented.
192 Key *server_key; /* ephemeral server key */
193 Key *ssh1_host_key; /* ssh1 host key */
194 Key **host_keys; /* all private host keys */
197 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
201 * Flag indicating whether the RSA server key needs to be regenerated.
202 * Is set in the SIGALRM handler and cleared when the key is regenerated.
204 static volatile sig_atomic_t key_do_regen = 0;
206 /* This is set to true when a signal is received. */
207 static volatile sig_atomic_t received_sighup = 0;
208 static volatile sig_atomic_t received_sigterm = 0;
210 /* session identifier, used by RSA-auth */
211 u_char session_id[16];
214 u_char *session_id2 = NULL;
215 u_int session_id2_len = 0;
217 /* record remote hostname or ip */
218 u_int utmp_len = MAXHOSTNAMELEN;
220 /* options.max_startup sized array of fd ints */
221 int *startup_pipes = NULL;
222 int startup_pipe; /* in child */
224 /* variables used for privilege separation */
225 int use_privsep = -1;
226 struct monitor *pmonitor = NULL;
228 /* global authentication context */
229 Authctxt *the_authctxt = NULL;
231 /* sshd_config buffer */
234 /* message to be displayed after login */
237 /* Prototypes for various functions defined later in this file. */
238 void destroy_sensitive_data(void);
239 void demote_sensitive_data(void);
241 static void do_ssh1_kex(void);
242 static void do_ssh2_kex(void);
245 * Close all listening sockets
248 close_listen_socks(void)
252 for (i = 0; i < num_listen_socks; i++)
253 close(listen_socks[i]);
254 num_listen_socks = -1;
258 close_startup_pipes(void)
263 for (i = 0; i < options.max_startups; i++)
264 if (startup_pipes[i] != -1)
265 close(startup_pipes[i]);
269 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
270 * the effect is to reread the configuration file (and to regenerate
276 sighup_handler(int sig)
278 int save_errno = errno;
281 signal(SIGHUP, sighup_handler);
286 * Called from the main program after receiving SIGHUP.
287 * Restarts the server.
292 logit("Received SIGHUP; restarting.");
293 close_listen_socks();
294 close_startup_pipes();
295 execv(saved_argv[0], saved_argv);
296 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
302 * Generic signal handler for terminating signals in the master daemon.
306 sigterm_handler(int sig)
308 received_sigterm = sig;
312 * SIGCHLD handler. This is called whenever a child dies. This will then
313 * reap any zombies left by exited children.
317 main_sigchld_handler(int sig)
319 int save_errno = errno;
323 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
324 (pid < 0 && errno == EINTR))
327 signal(SIGCHLD, main_sigchld_handler);
332 * Signal handler for the alarm after the login grace period has expired.
336 grace_alarm_handler(int sig)
338 /* XXX no idea how fix this signal handler */
340 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
341 kill(pmonitor->m_pid, SIGALRM);
343 /* Log error and exit. */
344 fatal("Timeout before authentication for %s", get_remote_ipaddr());
348 * Signal handler for the key regeneration alarm. Note that this
349 * alarm only occurs in the daemon waiting for connections, and it does not
350 * do anything with the private key or random state before forking.
351 * Thus there should be no concurrency control/asynchronous execution
355 generate_ephemeral_server_key(void)
360 verbose("Generating %s%d bit RSA key.",
361 sensitive_data.server_key ? "new " : "", options.server_key_bits);
362 if (sensitive_data.server_key != NULL)
363 key_free(sensitive_data.server_key);
364 sensitive_data.server_key = key_generate(KEY_RSA1,
365 options.server_key_bits);
366 verbose("RSA key generation complete.");
368 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
371 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
379 key_regeneration_alarm(int sig)
381 int save_errno = errno;
383 signal(SIGALRM, SIG_DFL);
389 sshd_exchange_identification(int sock_in, int sock_out)
393 int remote_major, remote_minor;
396 char buf[256]; /* Must not be larger than remote_version. */
397 char remote_version[256]; /* Must be at least as big as buf. */
399 if ((options.protocol & SSH_PROTO_1) &&
400 (options.protocol & SSH_PROTO_2)) {
401 major = PROTOCOL_MAJOR_1;
403 } else if (options.protocol & SSH_PROTO_2) {
404 major = PROTOCOL_MAJOR_2;
405 minor = PROTOCOL_MINOR_2;
407 major = PROTOCOL_MAJOR_1;
408 minor = PROTOCOL_MINOR_1;
410 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
411 server_version_string = xstrdup(buf);
413 /* Send our protocol version identification. */
414 if (atomicio(vwrite, sock_out, server_version_string,
415 strlen(server_version_string))
416 != strlen(server_version_string)) {
417 logit("Could not write ident string to %s", get_remote_ipaddr());
421 /* Read other sides version identification. */
422 memset(buf, 0, sizeof(buf));
423 for (i = 0; i < sizeof(buf) - 1; i++) {
424 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
425 logit("Did not receive identification string from %s",
426 get_remote_ipaddr());
429 if (buf[i] == '\r') {
431 /* Kludge for F-Secure Macintosh < 1.0.2 */
433 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
437 if (buf[i] == '\n') {
442 buf[sizeof(buf) - 1] = 0;
443 client_version_string = xstrdup(buf);
446 * Check that the versions match. In future this might accept
447 * several versions and set appropriate flags to handle them.
449 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
450 &remote_major, &remote_minor, remote_version) != 3) {
451 s = "Protocol mismatch.\n";
452 (void) atomicio(vwrite, sock_out, s, strlen(s));
455 logit("Bad protocol version identification '%.100s' from %s",
456 client_version_string, get_remote_ipaddr());
459 debug("Client protocol version %d.%d; client software version %.100s",
460 remote_major, remote_minor, remote_version);
462 compat_datafellows(remote_version);
464 if (datafellows & SSH_BUG_PROBE) {
465 logit("probed from %s with %s. Don't panic.",
466 get_remote_ipaddr(), client_version_string);
470 if (datafellows & SSH_BUG_SCANNER) {
471 logit("scanned from %s with %s. Don't panic.",
472 get_remote_ipaddr(), client_version_string);
477 switch (remote_major) {
479 if (remote_minor == 99) {
480 if (options.protocol & SSH_PROTO_2)
486 if (!(options.protocol & SSH_PROTO_1)) {
490 if (remote_minor < 3) {
491 packet_disconnect("Your ssh version is too old and "
492 "is no longer supported. Please install a newer version.");
493 } else if (remote_minor == 3) {
494 /* note that this disables agent-forwarding */
499 if (options.protocol & SSH_PROTO_2) {
508 chop(server_version_string);
509 debug("Local version string %.200s", server_version_string);
512 s = "Protocol major versions differ.\n";
513 (void) atomicio(vwrite, sock_out, s, strlen(s));
516 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
518 server_version_string, client_version_string);
523 /* Destroy the host and server keys. They will no longer be needed. */
525 destroy_sensitive_data(void)
529 if (sensitive_data.server_key) {
530 key_free(sensitive_data.server_key);
531 sensitive_data.server_key = NULL;
533 for (i = 0; i < options.num_host_key_files; i++) {
534 if (sensitive_data.host_keys[i]) {
535 key_free(sensitive_data.host_keys[i]);
536 sensitive_data.host_keys[i] = NULL;
539 sensitive_data.ssh1_host_key = NULL;
540 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
543 /* Demote private to public keys for network child */
545 demote_sensitive_data(void)
550 if (sensitive_data.server_key) {
551 tmp = key_demote(sensitive_data.server_key);
552 key_free(sensitive_data.server_key);
553 sensitive_data.server_key = tmp;
556 for (i = 0; i < options.num_host_key_files; i++) {
557 if (sensitive_data.host_keys[i]) {
558 tmp = key_demote(sensitive_data.host_keys[i]);
559 key_free(sensitive_data.host_keys[i]);
560 sensitive_data.host_keys[i] = tmp;
561 if (tmp->type == KEY_RSA1)
562 sensitive_data.ssh1_host_key = tmp;
566 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
570 privsep_preauth_child(void)
577 /* Enable challenge-response authentication for privilege separation */
578 privsep_challenge_enable();
580 for (i = 0; i < 256; i++)
581 rnd[i] = arc4random();
582 RAND_seed(rnd, sizeof(rnd));
584 /* Demote the private keys to public keys. */
585 demote_sensitive_data();
587 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
588 fatal("Privilege separation user %s does not exist",
590 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
593 /* Change our root directory */
594 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
595 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
597 if (chdir("/") == -1)
598 fatal("chdir(\"/\"): %s", strerror(errno));
600 /* Drop our privileges */
601 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
604 /* XXX not ready, too heavy after chroot */
605 do_setusercontext(pw);
607 gidset[0] = pw->pw_gid;
608 if (setgroups(1, gidset) < 0)
609 fatal("setgroups: %.100s", strerror(errno));
610 permanently_set_uid(pw);
615 privsep_preauth(Authctxt *authctxt)
620 /* Set up unprivileged child process to deal with network data */
621 pmonitor = monitor_init();
622 /* Store a pointer to the kex for later rekeying */
623 pmonitor->m_pkex = &xxx_kex;
627 fatal("fork of unprivileged child failed");
628 } else if (pid != 0) {
629 debug2("Network child is on pid %ld", (long)pid);
631 close(pmonitor->m_recvfd);
632 pmonitor->m_pid = pid;
633 monitor_child_preauth(authctxt, pmonitor);
634 close(pmonitor->m_sendfd);
637 monitor_sync(pmonitor);
639 /* Wait for the child's exit status */
640 while (waitpid(pid, &status, 0) < 0)
647 close(pmonitor->m_sendfd);
649 /* Demote the child */
650 if (getuid() == 0 || geteuid() == 0)
651 privsep_preauth_child();
652 setproctitle("%s", "[net]");
658 privsep_postauth(Authctxt *authctxt)
660 #ifdef DISABLE_FD_PASSING
663 if (authctxt->pw->pw_uid == 0 || options.use_login) {
665 /* File descriptor passing is broken or root login */
670 /* New socket pair */
671 monitor_reinit(pmonitor);
673 pmonitor->m_pid = fork();
674 if (pmonitor->m_pid == -1)
675 fatal("fork of unprivileged child failed");
676 else if (pmonitor->m_pid != 0) {
677 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
678 close(pmonitor->m_recvfd);
679 buffer_clear(&loginmsg);
680 monitor_child_postauth(pmonitor);
686 close(pmonitor->m_sendfd);
688 /* Demote the private keys to public keys. */
689 demote_sensitive_data();
691 /* Drop privileges */
692 do_setusercontext(authctxt->pw);
695 /* It is safe now to apply the key state */
696 monitor_apply_keystate(pmonitor);
699 * Tell the packet layer that authentication was successful, since
700 * this information is not part of the key state.
702 packet_set_authenticated();
706 list_hostkey_types(void)
714 for (i = 0; i < options.num_host_key_files; i++) {
715 Key *key = sensitive_data.host_keys[i];
721 if (buffer_len(&b) > 0)
722 buffer_append(&b, ",", 1);
723 p = key_ssh_name(key);
724 buffer_append(&b, p, strlen(p));
728 buffer_append(&b, "\0", 1);
729 ret = xstrdup(buffer_ptr(&b));
731 debug("list_hostkey_types: %s", ret);
736 get_hostkey_by_type(int type)
740 for (i = 0; i < options.num_host_key_files; i++) {
741 Key *key = sensitive_data.host_keys[i];
742 if (key != NULL && key->type == type)
749 get_hostkey_by_index(int ind)
751 if (ind < 0 || ind >= options.num_host_key_files)
753 return (sensitive_data.host_keys[ind]);
757 get_hostkey_index(Key *key)
761 for (i = 0; i < options.num_host_key_files; i++) {
762 if (key == sensitive_data.host_keys[i])
769 * returns 1 if connection should be dropped, 0 otherwise.
770 * dropping starts at connection #max_startups_begin with a probability
771 * of (max_startups_rate/100). the probability increases linearly until
772 * all connections are dropped for startups > max_startups
775 drop_connection(int startups)
779 if (startups < options.max_startups_begin)
781 if (startups >= options.max_startups)
783 if (options.max_startups_rate == 100)
786 p = 100 - options.max_startups_rate;
787 p *= startups - options.max_startups_begin;
788 p /= options.max_startups - options.max_startups_begin;
789 p += options.max_startups_rate;
790 r = arc4random() % 100;
792 debug("drop_connection: p %d, r %d", p, r);
793 return (r < p) ? 1 : 0;
799 fprintf(stderr, "%s, %s\n",
800 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
802 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
803 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
809 send_rexec_state(int fd, Buffer *conf)
813 debug3("%s: entering fd = %d config len %d", __func__, fd,
817 * Protocol from reexec master to child:
818 * string configuration
819 * u_int ephemeral_key_follows
820 * bignum e (only if ephemeral_key_follows == 1)
826 * string rngseed (only if OpenSSL is not self-seeded)
829 buffer_put_cstring(&m, buffer_ptr(conf));
831 if (sensitive_data.server_key != NULL &&
832 sensitive_data.server_key->type == KEY_RSA1) {
833 buffer_put_int(&m, 1);
834 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
835 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
836 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
837 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
838 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
839 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
841 buffer_put_int(&m, 0);
843 #ifndef OPENSSL_PRNG_ONLY
844 rexec_send_rng_seed(&m);
847 if (ssh_msg_send(fd, 0, &m) == -1)
848 fatal("%s: ssh_msg_send failed", __func__);
852 debug3("%s: done", __func__);
856 recv_rexec_state(int fd, Buffer *conf)
862 debug3("%s: entering fd = %d", __func__, fd);
866 if (ssh_msg_recv(fd, &m) == -1)
867 fatal("%s: ssh_msg_recv failed", __func__);
868 if (buffer_get_char(&m) != 0)
869 fatal("%s: rexec version mismatch", __func__);
871 cp = buffer_get_string(&m, &len);
873 buffer_append(conf, cp, len + 1);
876 if (buffer_get_int(&m)) {
877 if (sensitive_data.server_key != NULL)
878 key_free(sensitive_data.server_key);
879 sensitive_data.server_key = key_new_private(KEY_RSA1);
880 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
881 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
882 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
883 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
884 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
885 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
886 rsa_generate_additional_parameters(
887 sensitive_data.server_key->rsa);
890 #ifndef OPENSSL_PRNG_ONLY
891 rexec_recv_rng_seed(&m);
896 debug3("%s: done", __func__);
900 * Main program for the daemon.
903 main(int ac, char **av)
907 int opt, j, i, on = 1;
908 int sock_in = -1, sock_out = -1, newsock = -1;
912 struct sockaddr_storage from;
913 const char *remote_ip;
917 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
919 int listen_sock, maxfd;
920 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
924 int ret, key_used = 0;
926 #ifdef HAVE_SECUREWARE
927 (void)set_auth_parameters(ac, av);
929 __progname = ssh_get_progname(av[0]);
932 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
935 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
936 for (i = 0; i < ac; i++)
937 saved_argv[i] = xstrdup(av[i]);
938 saved_argv[i] = NULL;
940 #ifndef HAVE_SETPROCTITLE
941 /* Prepare for later setproctitle emulation */
942 compat_init_setproctitle(ac, av);
946 if (geteuid() == 0 && setgroups(0, NULL) == -1)
947 debug("setgroups(): %.200s", strerror(errno));
949 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
952 /* Initialize configuration options to their default values. */
953 initialize_server_options(&options);
955 /* Parse command-line arguments. */
956 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
959 options.address_family = AF_INET;
962 options.address_family = AF_INET6;
965 config_file_name = optarg;
968 if (debug_flag == 0) {
970 options.log_level = SYSLOG_LEVEL_DEBUG1;
971 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
994 options.log_level = SYSLOG_LEVEL_QUIET;
997 options.server_key_bits = (int)strtonum(optarg, 256,
1001 options.ports_from_cmdline = 1;
1002 if (options.num_ports >= MAX_PORTS) {
1003 fprintf(stderr, "too many ports.\n");
1006 options.ports[options.num_ports++] = a2port(optarg);
1007 if (options.ports[options.num_ports-1] == 0) {
1008 fprintf(stderr, "Bad port number.\n");
1013 if ((options.login_grace_time = convtime(optarg)) == -1) {
1014 fprintf(stderr, "Invalid login grace time.\n");
1019 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1020 fprintf(stderr, "Invalid key regeneration interval.\n");
1025 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1026 fprintf(stderr, "too many host keys.\n");
1029 options.host_key_files[options.num_host_key_files++] = optarg;
1035 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1036 if (utmp_len > MAXHOSTNAMELEN) {
1037 fprintf(stderr, "Invalid utmp length.\n");
1042 line = xstrdup(optarg);
1043 if (process_server_config_line(&options, line,
1044 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1054 if (rexeced_flag || inetd_flag)
1056 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1057 fatal("sshd re-exec requires execution with an absolute path");
1059 closefrom(REEXEC_MIN_FREE_FD);
1061 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1063 SSLeay_add_all_algorithms();
1066 * Force logging to stderr until we have loaded the private host
1067 * key (unless started from inetd)
1069 log_init(__progname,
1070 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1071 SYSLOG_LEVEL_INFO : options.log_level,
1072 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1073 SYSLOG_FACILITY_AUTH : options.log_facility,
1074 log_stderr || !inetd_flag);
1077 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1078 * root's environment
1080 if (getenv("KRB5CCNAME") != NULL)
1081 unsetenv("KRB5CCNAME");
1084 /* Cray can define user privs drop all privs now!
1085 * Not needed on PRIV_SU systems!
1090 sensitive_data.server_key = NULL;
1091 sensitive_data.ssh1_host_key = NULL;
1092 sensitive_data.have_ssh1_key = 0;
1093 sensitive_data.have_ssh2_key = 0;
1095 /* Fetch our configuration */
1098 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1100 load_server_config(config_file_name, &cfg);
1102 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1103 &cfg, NULL, NULL, NULL);
1107 /* Fill in default values for those options not explicitly set. */
1108 fill_default_server_options(&options);
1110 /* set default channel AF */
1111 channel_set_af(options.address_family);
1113 /* Check that there are no remaining arguments. */
1115 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1119 debug("sshd version %.100s", SSH_RELEASE);
1121 /* load private host keys */
1122 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1124 for (i = 0; i < options.num_host_key_files; i++)
1125 sensitive_data.host_keys[i] = NULL;
1127 for (i = 0; i < options.num_host_key_files; i++) {
1128 key = key_load_private(options.host_key_files[i], "", NULL);
1129 sensitive_data.host_keys[i] = key;
1131 error("Could not load host key: %s",
1132 options.host_key_files[i]);
1133 sensitive_data.host_keys[i] = NULL;
1136 switch (key->type) {
1138 sensitive_data.ssh1_host_key = key;
1139 sensitive_data.have_ssh1_key = 1;
1143 sensitive_data.have_ssh2_key = 1;
1146 debug("private host key: #%d type %d %s", i, key->type,
1149 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1150 logit("Disabling protocol version 1. Could not load host key");
1151 options.protocol &= ~SSH_PROTO_1;
1153 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1154 logit("Disabling protocol version 2. Could not load host key");
1155 options.protocol &= ~SSH_PROTO_2;
1157 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1158 logit("sshd: no hostkeys available -- exiting.");
1162 /* Check certain values for sanity. */
1163 if (options.protocol & SSH_PROTO_1) {
1164 if (options.server_key_bits < 512 ||
1165 options.server_key_bits > 32768) {
1166 fprintf(stderr, "Bad server key size.\n");
1170 * Check that server and host key lengths differ sufficiently. This
1171 * is necessary to make double encryption work with rsaref. Oh, I
1172 * hate software patents. I dont know if this can go? Niels
1174 if (options.server_key_bits >
1175 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1176 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1177 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1178 SSH_KEY_BITS_RESERVED) {
1179 options.server_key_bits =
1180 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1181 SSH_KEY_BITS_RESERVED;
1182 debug("Forcing server key to %d bits to make it differ from host key.",
1183 options.server_key_bits);
1190 if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1191 fatal("Privilege separation user %s does not exist",
1193 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1194 (S_ISDIR(st.st_mode) == 0))
1195 fatal("Missing privilege separation directory: %s",
1196 _PATH_PRIVSEP_CHROOT_DIR);
1199 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1200 (st.st_uid != getuid () ||
1201 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1203 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1205 fatal("%s must be owned by root and not group or "
1206 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1209 /* Configuration looks good, so exit if in test mode. */
1214 * Clear out any supplemental groups we may have inherited. This
1215 * prevents inadvertent creation of files with bad modes (in the
1216 * portable version at least, it's certainly possible for PAM
1217 * to create a file, and we can't control the code in every
1218 * module which might be used).
1220 if (setgroups(0, NULL) < 0)
1221 debug("setgroups() failed: %.200s", strerror(errno));
1224 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1225 for (i = 0; i < rexec_argc; i++) {
1226 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1227 rexec_argv[i] = saved_argv[i];
1229 rexec_argv[rexec_argc] = "-R";
1230 rexec_argv[rexec_argc + 1] = NULL;
1233 /* Initialize the log (it is reinitialized below in case we forked). */
1234 if (debug_flag && (!inetd_flag || rexeced_flag))
1236 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1239 * If not in debugging mode, and not started from inetd, disconnect
1240 * from the controlling terminal, and fork. The original process
1243 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1246 #endif /* TIOCNOTTY */
1247 if (daemon(0, 0) < 0)
1248 fatal("daemon() failed: %.200s", strerror(errno));
1250 /* Disconnect from the controlling tty. */
1252 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1254 (void) ioctl(fd, TIOCNOTTY, NULL);
1257 #endif /* TIOCNOTTY */
1259 /* Reinitialize the log (because of the fork above). */
1260 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1262 /* Initialize the random number generator. */
1265 /* Chdir to the root directory so that the current disk can be
1266 unmounted if desired. */
1269 /* ignore SIGPIPE */
1270 signal(SIGPIPE, SIG_IGN);
1272 /* Start listening for a socket, unless started from inetd. */
1278 close(REEXEC_CONFIG_PASS_FD);
1279 sock_in = sock_out = dup(STDIN_FILENO);
1281 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1282 close(REEXEC_STARTUP_PIPE_FD);
1285 sock_in = dup(STDIN_FILENO);
1286 sock_out = dup(STDOUT_FILENO);
1289 * We intentionally do not close the descriptors 0, 1, and 2
1290 * as our code for setting the descriptors won't work if
1291 * ttyfd happens to be one of those.
1293 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1294 dup2(fd, STDIN_FILENO);
1295 dup2(fd, STDOUT_FILENO);
1296 if (fd > STDOUT_FILENO)
1299 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1300 if ((options.protocol & SSH_PROTO_1) &&
1301 sensitive_data.server_key == NULL)
1302 generate_ephemeral_server_key();
1304 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1305 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1307 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1308 fatal("Too many listen sockets. "
1309 "Enlarge MAX_LISTEN_SOCKS");
1310 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1311 ntop, sizeof(ntop), strport, sizeof(strport),
1312 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1313 error("getnameinfo failed: %.100s",
1314 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1318 /* Create socket for listening. */
1319 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1321 if (listen_sock < 0) {
1322 /* kernel may not support ipv6 */
1323 verbose("socket: %.100s", strerror(errno));
1326 if (set_nonblock(listen_sock) == -1) {
1331 * Set socket options.
1332 * Allow local port reuse in TIME_WAIT.
1334 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1335 &on, sizeof(on)) == -1)
1336 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1338 debug("Bind to port %s on %s.", strport, ntop);
1340 /* Bind the socket to the desired port. */
1341 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1343 error("Bind to port %s on %s failed: %.200s.",
1344 strport, ntop, strerror(errno));
1348 listen_socks[num_listen_socks] = listen_sock;
1351 /* Start listening on the port. */
1352 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1353 fatal("listen on [%s]:%s: %.100s",
1354 ntop, strport, strerror(errno));
1355 logit("Server listening on %s port %s.", ntop, strport);
1357 freeaddrinfo(options.listen_addrs);
1359 if (!num_listen_socks)
1360 fatal("Cannot bind any address.");
1362 if (options.protocol & SSH_PROTO_1)
1363 generate_ephemeral_server_key();
1366 * Arrange to restart on SIGHUP. The handler needs
1369 signal(SIGHUP, sighup_handler);
1371 signal(SIGTERM, sigterm_handler);
1372 signal(SIGQUIT, sigterm_handler);
1374 /* Arrange SIGCHLD to be caught. */
1375 signal(SIGCHLD, main_sigchld_handler);
1377 /* Write out the pid file after the sigterm handler is setup */
1380 * Record our pid in /var/run/sshd.pid to make it
1381 * easier to kill the correct sshd. We don't want to
1382 * do this before the bind above because the bind will
1383 * fail if there already is a daemon, and this will
1384 * overwrite any old pid in the file.
1386 f = fopen(options.pid_file, "wb");
1388 error("Couldn't create pid file \"%s\": %s",
1389 options.pid_file, strerror(errno));
1391 fprintf(f, "%ld\n", (long) getpid());
1396 /* setup fd set for listen */
1399 for (i = 0; i < num_listen_socks; i++)
1400 if (listen_socks[i] > maxfd)
1401 maxfd = listen_socks[i];
1402 /* pipes connected to unauthenticated childs */
1403 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1404 for (i = 0; i < options.max_startups; i++)
1405 startup_pipes[i] = -1;
1408 * Stay listening for connections until the system crashes or
1409 * the daemon is killed with a signal.
1412 if (received_sighup)
1416 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1419 for (i = 0; i < num_listen_socks; i++)
1420 FD_SET(listen_socks[i], fdset);
1421 for (i = 0; i < options.max_startups; i++)
1422 if (startup_pipes[i] != -1)
1423 FD_SET(startup_pipes[i], fdset);
1425 /* Wait in select until there is a connection. */
1426 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1427 if (ret < 0 && errno != EINTR)
1428 error("select: %.100s", strerror(errno));
1429 if (received_sigterm) {
1430 logit("Received signal %d; terminating.",
1431 (int) received_sigterm);
1432 close_listen_socks();
1433 unlink(options.pid_file);
1436 if (key_used && key_do_regen) {
1437 generate_ephemeral_server_key();
1444 for (i = 0; i < options.max_startups; i++)
1445 if (startup_pipes[i] != -1 &&
1446 FD_ISSET(startup_pipes[i], fdset)) {
1448 * the read end of the pipe is ready
1449 * if the child has closed the pipe
1450 * after successful authentication
1451 * or if the child has died
1453 close(startup_pipes[i]);
1454 startup_pipes[i] = -1;
1457 for (i = 0; i < num_listen_socks; i++) {
1458 if (!FD_ISSET(listen_socks[i], fdset))
1460 fromlen = sizeof(from);
1461 newsock = accept(listen_socks[i],
1462 (struct sockaddr *)&from, &fromlen);
1464 if (errno != EINTR && errno != EWOULDBLOCK)
1465 error("accept: %.100s", strerror(errno));
1468 if (unset_nonblock(newsock) == -1) {
1472 if (drop_connection(startups) == 1) {
1473 debug("drop connection #%d", startups);
1477 if (pipe(startup_p) == -1) {
1482 if (rexec_flag && socketpair(AF_UNIX,
1483 SOCK_STREAM, 0, config_s) == -1) {
1484 error("reexec socketpair: %s",
1487 close(startup_p[0]);
1488 close(startup_p[1]);
1492 for (j = 0; j < options.max_startups; j++)
1493 if (startup_pipes[j] == -1) {
1494 startup_pipes[j] = startup_p[0];
1495 if (maxfd < startup_p[0])
1496 maxfd = startup_p[0];
1502 * Got connection. Fork a child to handle it, unless
1503 * we are in debugging mode.
1507 * In debugging mode. Close the listening
1508 * socket, and start processing the
1509 * connection without forking.
1511 debug("Server will not fork when running in debugging mode.");
1512 close_listen_socks();
1515 close(startup_p[0]);
1516 close(startup_p[1]);
1520 send_rexec_state(config_s[0],
1527 * Normal production daemon. Fork, and have
1528 * the child process the connection. The
1529 * parent continues listening.
1531 if ((pid = fork()) == 0) {
1533 * Child. Close the listening and
1534 * max_startup sockets. Start using
1535 * the accepted socket. Reinitialize
1536 * logging (since our pid has changed).
1537 * We break out of the loop to handle
1540 startup_pipe = startup_p[1];
1541 close_startup_pipes();
1542 close_listen_socks();
1545 log_init(__progname,
1547 options.log_facility,
1555 /* Parent. Stay in the loop. */
1557 error("fork: %.100s", strerror(errno));
1559 debug("Forked child %ld.", (long)pid);
1561 close(startup_p[1]);
1564 send_rexec_state(config_s[0], &cfg);
1570 * Mark that the key has been used (it
1571 * was "given" to the child).
1573 if ((options.protocol & SSH_PROTO_1) &&
1575 /* Schedule server key regeneration alarm. */
1576 signal(SIGALRM, key_regeneration_alarm);
1577 alarm(options.key_regeneration_time);
1584 /* child process check (or debug mode) */
1585 if (num_listen_socks < 0)
1590 /* This is the child processing a new connection. */
1591 setproctitle("%s", "[accepted]");
1594 * Create a new session and process group since the 4.4BSD
1595 * setlogin() affects the entire process group. We don't
1596 * want the child to be able to affect the parent.
1598 #if !defined(SSHD_ACQUIRES_CTTY)
1600 * If setsid is called, on some platforms sshd will later acquire a
1601 * controlling terminal which will result in "could not set
1602 * controlling tty" errors.
1604 if (!debug_flag && !inetd_flag && setsid() < 0)
1605 error("setsid: %.100s", strerror(errno));
1611 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1612 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1613 dup2(newsock, STDIN_FILENO);
1614 dup2(STDIN_FILENO, STDOUT_FILENO);
1615 if (startup_pipe == -1)
1616 close(REEXEC_STARTUP_PIPE_FD);
1618 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1620 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1622 if (startup_pipe != -1)
1623 close(startup_pipe);
1625 execv(rexec_argv[0], rexec_argv);
1627 /* Reexec has failed, fall back and continue */
1628 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1629 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1630 log_init(__progname, options.log_level,
1631 options.log_facility, log_stderr);
1634 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1636 close(REEXEC_CONFIG_PASS_FD);
1637 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1638 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1639 dup2(fd, STDIN_FILENO);
1640 dup2(fd, STDOUT_FILENO);
1641 if (fd > STDERR_FILENO)
1644 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1645 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1649 * Disable the key regeneration alarm. We will not regenerate the
1650 * key since we are no longer in a position to give it to anyone. We
1651 * will not restart on SIGHUP since it no longer makes sense.
1654 signal(SIGALRM, SIG_DFL);
1655 signal(SIGHUP, SIG_DFL);
1656 signal(SIGTERM, SIG_DFL);
1657 signal(SIGQUIT, SIG_DFL);
1658 signal(SIGCHLD, SIG_DFL);
1659 signal(SIGINT, SIG_DFL);
1662 * Register our connection. This turns encryption off because we do
1665 packet_set_connection(sock_in, sock_out);
1666 packet_set_server();
1668 /* Set SO_KEEPALIVE if requested. */
1669 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1670 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1671 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1673 if ((remote_port = get_remote_port()) < 0) {
1674 debug("get_remote_port failed");
1679 * We use get_canonical_hostname with usedns = 0 instead of
1680 * get_remote_ipaddr here so IP options will be checked.
1682 (void) get_canonical_hostname(0);
1684 * The rest of the code depends on the fact that
1685 * get_remote_ipaddr() caches the remote ip, even if
1686 * the socket goes away.
1688 remote_ip = get_remote_ipaddr();
1690 #ifdef SSH_AUDIT_EVENTS
1691 audit_connection_from(remote_ip, remote_port);
1694 /* Check whether logins are denied from this host. */
1695 if (packet_connection_is_on_socket()) {
1696 struct request_info req;
1698 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1701 if (!hosts_access(&req)) {
1702 debug("Connection refused by tcp wrapper");
1705 fatal("libwrap refuse returns");
1708 #endif /* LIBWRAP */
1710 /* Log the connection. */
1711 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1714 * We don't want to listen forever unless the other side
1715 * successfully authenticates itself. So we set up an alarm which is
1716 * cleared after successful authentication. A limit of zero
1717 * indicates no limit. Note that we don't set the alarm in debugging
1718 * mode; it is just annoying to have the server exit just when you
1719 * are about to discover the bug.
1721 signal(SIGALRM, grace_alarm_handler);
1723 alarm(options.login_grace_time);
1725 sshd_exchange_identification(sock_in, sock_out);
1727 packet_set_nonblocking();
1729 /* allocate authentication context */
1730 authctxt = xcalloc(1, sizeof(*authctxt));
1732 authctxt->loginmsg = &loginmsg;
1734 /* XXX global for cleanup, access from other modules */
1735 the_authctxt = authctxt;
1737 /* prepare buffer to collect messages to display to user after login */
1738 buffer_init(&loginmsg);
1741 if (privsep_preauth(authctxt) == 1)
1744 /* perform the key exchange */
1745 /* authenticate user and start session */
1748 do_authentication2(authctxt);
1751 do_authentication(authctxt);
1754 * If we use privilege separation, the unprivileged child transfers
1755 * the current keystate and exits
1758 mm_send_keystate(pmonitor);
1764 * Cancel the alarm we set to limit the time taken for
1768 signal(SIGALRM, SIG_DFL);
1769 if (startup_pipe != -1) {
1770 close(startup_pipe);
1774 #ifdef SSH_AUDIT_EVENTS
1775 audit_event(SSH_AUTH_SUCCESS);
1779 * In privilege separation, we fork another child and prepare
1780 * file descriptor passing.
1783 privsep_postauth(authctxt);
1784 /* the monitor process [priv] will not return */
1786 destroy_sensitive_data();
1789 /* Start session. */
1790 do_authenticated(authctxt);
1792 /* The connection has been terminated. */
1793 verbose("Closing connection to %.100s", remote_ip);
1796 if (options.use_pam)
1798 #endif /* USE_PAM */
1800 #ifdef SSH_AUDIT_EVENTS
1801 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1813 * Decrypt session_key_int using our private server key and private host key
1814 * (key with larger modulus first).
1817 ssh1_session_key(BIGNUM *session_key_int)
1821 if (BN_cmp(sensitive_data.server_key->rsa->n,
1822 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1823 /* Server key has bigger modulus. */
1824 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1825 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1826 SSH_KEY_BITS_RESERVED) {
1827 fatal("do_connection: %s: "
1828 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1829 get_remote_ipaddr(),
1830 BN_num_bits(sensitive_data.server_key->rsa->n),
1831 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1832 SSH_KEY_BITS_RESERVED);
1834 if (rsa_private_decrypt(session_key_int, session_key_int,
1835 sensitive_data.server_key->rsa) <= 0)
1837 if (rsa_private_decrypt(session_key_int, session_key_int,
1838 sensitive_data.ssh1_host_key->rsa) <= 0)
1841 /* Host key has bigger modulus (or they are equal). */
1842 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1843 BN_num_bits(sensitive_data.server_key->rsa->n) +
1844 SSH_KEY_BITS_RESERVED) {
1845 fatal("do_connection: %s: "
1846 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1847 get_remote_ipaddr(),
1848 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1849 BN_num_bits(sensitive_data.server_key->rsa->n),
1850 SSH_KEY_BITS_RESERVED);
1852 if (rsa_private_decrypt(session_key_int, session_key_int,
1853 sensitive_data.ssh1_host_key->rsa) < 0)
1855 if (rsa_private_decrypt(session_key_int, session_key_int,
1856 sensitive_data.server_key->rsa) < 0)
1869 BIGNUM *session_key_int;
1870 u_char session_key[SSH_SESSION_KEY_LENGTH];
1872 u_int cipher_type, auth_mask, protocol_flags;
1876 * Generate check bytes that the client must send back in the user
1877 * packet in order for it to be accepted; this is used to defy ip
1878 * spoofing attacks. Note that this only works against somebody
1879 * doing IP spoofing from a remote machine; any machine on the local
1880 * network can still see outgoing packets and catch the random
1881 * cookie. This only affects rhosts authentication, and this is one
1882 * of the reasons why it is inherently insecure.
1884 for (i = 0; i < 8; i++) {
1887 cookie[i] = rnd & 0xff;
1892 * Send our public key. We include in the packet 64 bits of random
1893 * data that must be matched in the reply in order to prevent IP
1896 packet_start(SSH_SMSG_PUBLIC_KEY);
1897 for (i = 0; i < 8; i++)
1898 packet_put_char(cookie[i]);
1900 /* Store our public server RSA key. */
1901 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1902 packet_put_bignum(sensitive_data.server_key->rsa->e);
1903 packet_put_bignum(sensitive_data.server_key->rsa->n);
1905 /* Store our public host RSA key. */
1906 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1907 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1908 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1910 /* Put protocol flags. */
1911 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1913 /* Declare which ciphers we support. */
1914 packet_put_int(cipher_mask_ssh1(0));
1916 /* Declare supported authentication types. */
1918 if (options.rhosts_rsa_authentication)
1919 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1920 if (options.rsa_authentication)
1921 auth_mask |= 1 << SSH_AUTH_RSA;
1922 if (options.challenge_response_authentication == 1)
1923 auth_mask |= 1 << SSH_AUTH_TIS;
1924 if (options.password_authentication)
1925 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1926 packet_put_int(auth_mask);
1928 /* Send the packet and wait for it to be sent. */
1930 packet_write_wait();
1932 debug("Sent %d bit server key and %d bit host key.",
1933 BN_num_bits(sensitive_data.server_key->rsa->n),
1934 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1936 /* Read clients reply (cipher type and session key). */
1937 packet_read_expect(SSH_CMSG_SESSION_KEY);
1939 /* Get cipher type and check whether we accept this. */
1940 cipher_type = packet_get_char();
1942 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1943 packet_disconnect("Warning: client selects unsupported cipher.");
1945 /* Get check bytes from the packet. These must match those we
1946 sent earlier with the public key packet. */
1947 for (i = 0; i < 8; i++)
1948 if (cookie[i] != packet_get_char())
1949 packet_disconnect("IP Spoofing check bytes do not match.");
1951 debug("Encryption type: %.200s", cipher_name(cipher_type));
1953 /* Get the encrypted integer. */
1954 if ((session_key_int = BN_new()) == NULL)
1955 fatal("do_ssh1_kex: BN_new failed");
1956 packet_get_bignum(session_key_int);
1958 protocol_flags = packet_get_int();
1959 packet_set_protocol_flags(protocol_flags);
1962 /* Decrypt session_key_int using host/server keys */
1963 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1966 * Extract session key from the decrypted integer. The key is in the
1967 * least significant 256 bits of the integer; the first byte of the
1968 * key is in the highest bits.
1971 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1972 len = BN_num_bytes(session_key_int);
1973 if (len < 0 || (u_int)len > sizeof(session_key)) {
1974 error("do_connection: bad session key len from %s: "
1975 "session_key_int %d > sizeof(session_key) %lu",
1976 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1979 memset(session_key, 0, sizeof(session_key));
1980 BN_bn2bin(session_key_int,
1981 session_key + sizeof(session_key) - len);
1983 derive_ssh1_session_id(
1984 sensitive_data.ssh1_host_key->rsa->n,
1985 sensitive_data.server_key->rsa->n,
1986 cookie, session_id);
1988 * Xor the first 16 bytes of the session key with the
1991 for (i = 0; i < 16; i++)
1992 session_key[i] ^= session_id[i];
1996 int bytes = BN_num_bytes(session_key_int);
1997 u_char *buf = xmalloc(bytes);
2000 logit("do_connection: generating a fake encryption key");
2001 BN_bn2bin(session_key_int, buf);
2003 MD5_Update(&md, buf, bytes);
2004 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2005 MD5_Final(session_key, &md);
2007 MD5_Update(&md, session_key, 16);
2008 MD5_Update(&md, buf, bytes);
2009 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2010 MD5_Final(session_key + 16, &md);
2011 memset(buf, 0, bytes);
2013 for (i = 0; i < 16; i++)
2014 session_id[i] = session_key[i] ^ session_key[i + 16];
2016 /* Destroy the private and public keys. No longer. */
2017 destroy_sensitive_data();
2020 mm_ssh1_session_id(session_id);
2022 /* Destroy the decrypted integer. It is no longer needed. */
2023 BN_clear_free(session_key_int);
2025 /* Set the session key. From this on all communications will be encrypted. */
2026 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2028 /* Destroy our copy of the session key. It is no longer needed. */
2029 memset(session_key, 0, sizeof(session_key));
2031 debug("Received session key; encryption turned on.");
2033 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2034 packet_start(SSH_SMSG_SUCCESS);
2036 packet_write_wait();
2040 * SSH2 key exchange: diffie-hellman-group1-sha1
2047 if (options.ciphers != NULL) {
2048 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2049 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2051 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2052 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2053 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2054 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2056 if (options.macs != NULL) {
2057 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2058 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2060 if (options.compression == COMP_NONE) {
2061 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2062 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2063 } else if (options.compression == COMP_DELAYED) {
2064 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2065 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2068 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2070 /* start key exchange */
2071 kex = kex_setup(myproposal);
2072 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2073 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2074 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2075 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2077 kex->client_version_string=client_version_string;
2078 kex->server_version_string=server_version_string;
2079 kex->load_host_key=&get_hostkey_by_type;
2080 kex->host_key_index=&get_hostkey_index;
2084 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2086 session_id2 = kex->session_id;
2087 session_id2_len = kex->session_id_len;
2090 /* send 1st encrypted/maced/compressed message */
2091 packet_start(SSH2_MSG_IGNORE);
2092 packet_put_cstring("markus");
2094 packet_write_wait();
2099 /* server specific fatal cleanup */
2104 do_cleanup(the_authctxt);
2105 #ifdef SSH_AUDIT_EVENTS
2106 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2107 if (!use_privsep || mm_is_monitor())
2108 audit_event(SSH_CONNECTION_ABANDON);