2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * This program is the ssh daemon. It listens for connections from clients,
6 * and performs authentication, executes use commands or shell, and forwards
7 * information to/from the application to the user client over an encrypted
8 * connection. This can also handle forwarding of X11, TCP/IP, and
9 * authentication agent connections.
11 * As far as I am concerned, the code I have written for this software
12 * can be used freely for any purpose. Any derived versions of this
13 * software must be clearly marked as such, and if the derived work is
14 * incompatible with the protocol description in the RFC file, it must be
15 * called by a name other than "ssh" or "Secure Shell".
17 * SSH2 implementation:
18 * Privilege Separation:
20 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
21 * Copyright (c) 2002 Niels Provos. All rights reserved.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the above copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
32 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
33 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
34 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
35 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
36 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
37 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
38 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
39 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
40 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
41 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
45 RCSID("$OpenBSD: sshd.c,v 1.308 2005/02/08 22:24:57 dtucker Exp $");
48 #include <openssl/dh.h>
49 #include <openssl/bn.h>
50 #include <openssl/md5.h>
51 #include <openssl/rand.h>
52 #ifdef HAVE_SECUREWARE
53 #include <sys/security.h>
78 #include "myproposal.h"
80 #include "pathnames.h"
89 #include "monitor_mm.h"
91 #include "monitor_wrap.h"
92 #include "monitor_fdpass.h"
97 int allow_severity = LOG_INFO;
98 int deny_severity = LOG_WARNING;
106 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
107 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
108 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
109 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
111 extern char *__progname;
113 /* Server configuration options. */
114 ServerOptions options;
116 /* Name of the server configuration file. */
117 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
120 * Debug mode flag. This can be set on the command line. If debug
121 * mode is enabled, extra debugging output will be sent to the system
122 * log, the daemon will not go to background, and will exit after processing
123 * the first connection.
127 /* Flag indicating that the daemon should only test the configuration and keys. */
130 /* Flag indicating that the daemon is being started from inetd. */
133 /* Flag indicating that sshd should not detach and become a daemon. */
134 int no_daemon_flag = 0;
136 /* debug goes to stderr unless inetd_flag is set */
139 /* Saved arguments to main(). */
144 int rexeced_flag = 0;
150 * The sockets that the server is listening; this is used in the SIGHUP
153 #define MAX_LISTEN_SOCKS 16
154 int listen_socks[MAX_LISTEN_SOCKS];
155 int num_listen_socks = 0;
158 * the client's version string, passed by sshd2 in compat mode. if != NULL,
159 * sshd will skip the version-number exchange
161 char *client_version_string = NULL;
162 char *server_version_string = NULL;
164 /* for rekeying XXX fixme */
168 * Any really sensitive data in the application is contained in this
169 * structure. The idea is that this structure could be locked into memory so
170 * that the pages do not get written into swap. However, there are some
171 * problems. The private key contains BIGNUMs, and we do not (in principle)
172 * have access to the internals of them, and locking just the structure is
173 * not very useful. Currently, memory locking is not implemented.
176 Key *server_key; /* ephemeral server key */
177 Key *ssh1_host_key; /* ssh1 host key */
178 Key **host_keys; /* all private host keys */
181 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
185 * Flag indicating whether the RSA server key needs to be regenerated.
186 * Is set in the SIGALRM handler and cleared when the key is regenerated.
188 static volatile sig_atomic_t key_do_regen = 0;
190 /* This is set to true when a signal is received. */
191 static volatile sig_atomic_t received_sighup = 0;
192 static volatile sig_atomic_t received_sigterm = 0;
194 /* session identifier, used by RSA-auth */
195 u_char session_id[16];
198 u_char *session_id2 = NULL;
199 u_int session_id2_len = 0;
201 /* record remote hostname or ip */
202 u_int utmp_len = MAXHOSTNAMELEN;
204 /* options.max_startup sized array of fd ints */
205 int *startup_pipes = NULL;
206 int startup_pipe; /* in child */
208 /* variables used for privilege separation */
210 struct monitor *pmonitor = NULL;
212 /* global authentication context */
213 Authctxt *the_authctxt = NULL;
215 /* message to be displayed after login */
218 /* Prototypes for various functions defined later in this file. */
219 void destroy_sensitive_data(void);
220 void demote_sensitive_data(void);
222 static void do_ssh1_kex(void);
223 static void do_ssh2_kex(void);
226 * Close all listening sockets
229 close_listen_socks(void)
233 for (i = 0; i < num_listen_socks; i++)
234 close(listen_socks[i]);
235 num_listen_socks = -1;
239 close_startup_pipes(void)
244 for (i = 0; i < options.max_startups; i++)
245 if (startup_pipes[i] != -1)
246 close(startup_pipes[i]);
250 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
251 * the effect is to reread the configuration file (and to regenerate
255 sighup_handler(int sig)
257 int save_errno = errno;
260 signal(SIGHUP, sighup_handler);
265 * Called from the main program after receiving SIGHUP.
266 * Restarts the server.
271 logit("Received SIGHUP; restarting.");
272 close_listen_socks();
273 close_startup_pipes();
274 execv(saved_argv[0], saved_argv);
275 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
281 * Generic signal handler for terminating signals in the master daemon.
284 sigterm_handler(int sig)
286 received_sigterm = sig;
290 * SIGCHLD handler. This is called whenever a child dies. This will then
291 * reap any zombies left by exited children.
294 main_sigchld_handler(int sig)
296 int save_errno = errno;
300 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
301 (pid < 0 && errno == EINTR))
304 signal(SIGCHLD, main_sigchld_handler);
309 * Signal handler for the alarm after the login grace period has expired.
312 grace_alarm_handler(int sig)
314 /* XXX no idea how fix this signal handler */
316 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
317 kill(pmonitor->m_pid, SIGALRM);
319 /* Log error and exit. */
320 fatal("Timeout before authentication for %s", get_remote_ipaddr());
324 * Signal handler for the key regeneration alarm. Note that this
325 * alarm only occurs in the daemon waiting for connections, and it does not
326 * do anything with the private key or random state before forking.
327 * Thus there should be no concurrency control/asynchronous execution
331 generate_ephemeral_server_key(void)
336 verbose("Generating %s%d bit RSA key.",
337 sensitive_data.server_key ? "new " : "", options.server_key_bits);
338 if (sensitive_data.server_key != NULL)
339 key_free(sensitive_data.server_key);
340 sensitive_data.server_key = key_generate(KEY_RSA1,
341 options.server_key_bits);
342 verbose("RSA key generation complete.");
344 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
347 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
354 key_regeneration_alarm(int sig)
356 int save_errno = errno;
358 signal(SIGALRM, SIG_DFL);
364 sshd_exchange_identification(int sock_in, int sock_out)
367 int remote_major, remote_minor;
370 char buf[256]; /* Must not be larger than remote_version. */
371 char remote_version[256]; /* Must be at least as big as buf. */
373 if ((options.protocol & SSH_PROTO_1) &&
374 (options.protocol & SSH_PROTO_2)) {
375 major = PROTOCOL_MAJOR_1;
377 } else if (options.protocol & SSH_PROTO_2) {
378 major = PROTOCOL_MAJOR_2;
379 minor = PROTOCOL_MINOR_2;
381 major = PROTOCOL_MAJOR_1;
382 minor = PROTOCOL_MINOR_1;
384 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
385 server_version_string = xstrdup(buf);
387 /* Send our protocol version identification. */
388 if (atomicio(vwrite, sock_out, server_version_string,
389 strlen(server_version_string))
390 != strlen(server_version_string)) {
391 logit("Could not write ident string to %s", get_remote_ipaddr());
395 /* Read other sides version identification. */
396 memset(buf, 0, sizeof(buf));
397 for (i = 0; i < sizeof(buf) - 1; i++) {
398 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
399 logit("Did not receive identification string from %s",
400 get_remote_ipaddr());
403 if (buf[i] == '\r') {
405 /* Kludge for F-Secure Macintosh < 1.0.2 */
407 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
411 if (buf[i] == '\n') {
416 buf[sizeof(buf) - 1] = 0;
417 client_version_string = xstrdup(buf);
420 * Check that the versions match. In future this might accept
421 * several versions and set appropriate flags to handle them.
423 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
424 &remote_major, &remote_minor, remote_version) != 3) {
425 s = "Protocol mismatch.\n";
426 (void) atomicio(vwrite, sock_out, s, strlen(s));
429 logit("Bad protocol version identification '%.100s' from %s",
430 client_version_string, get_remote_ipaddr());
433 debug("Client protocol version %d.%d; client software version %.100s",
434 remote_major, remote_minor, remote_version);
436 compat_datafellows(remote_version);
438 if (datafellows & SSH_BUG_PROBE) {
439 logit("probed from %s with %s. Don't panic.",
440 get_remote_ipaddr(), client_version_string);
444 if (datafellows & SSH_BUG_SCANNER) {
445 logit("scanned from %s with %s. Don't panic.",
446 get_remote_ipaddr(), client_version_string);
451 switch (remote_major) {
453 if (remote_minor == 99) {
454 if (options.protocol & SSH_PROTO_2)
460 if (!(options.protocol & SSH_PROTO_1)) {
464 if (remote_minor < 3) {
465 packet_disconnect("Your ssh version is too old and "
466 "is no longer supported. Please install a newer version.");
467 } else if (remote_minor == 3) {
468 /* note that this disables agent-forwarding */
473 if (options.protocol & SSH_PROTO_2) {
482 chop(server_version_string);
483 debug("Local version string %.200s", server_version_string);
486 s = "Protocol major versions differ.\n";
487 (void) atomicio(vwrite, sock_out, s, strlen(s));
490 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
492 server_version_string, client_version_string);
497 /* Destroy the host and server keys. They will no longer be needed. */
499 destroy_sensitive_data(void)
503 if (sensitive_data.server_key) {
504 key_free(sensitive_data.server_key);
505 sensitive_data.server_key = NULL;
507 for (i = 0; i < options.num_host_key_files; i++) {
508 if (sensitive_data.host_keys[i]) {
509 key_free(sensitive_data.host_keys[i]);
510 sensitive_data.host_keys[i] = NULL;
513 sensitive_data.ssh1_host_key = NULL;
514 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
517 /* Demote private to public keys for network child */
519 demote_sensitive_data(void)
524 if (sensitive_data.server_key) {
525 tmp = key_demote(sensitive_data.server_key);
526 key_free(sensitive_data.server_key);
527 sensitive_data.server_key = tmp;
530 for (i = 0; i < options.num_host_key_files; i++) {
531 if (sensitive_data.host_keys[i]) {
532 tmp = key_demote(sensitive_data.host_keys[i]);
533 key_free(sensitive_data.host_keys[i]);
534 sensitive_data.host_keys[i] = tmp;
535 if (tmp->type == KEY_RSA1)
536 sensitive_data.ssh1_host_key = tmp;
540 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
544 privsep_preauth_child(void)
551 /* Enable challenge-response authentication for privilege separation */
552 privsep_challenge_enable();
554 for (i = 0; i < 256; i++)
555 rnd[i] = arc4random();
556 RAND_seed(rnd, sizeof(rnd));
558 /* Demote the private keys to public keys. */
559 demote_sensitive_data();
561 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
562 fatal("Privilege separation user %s does not exist",
564 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
567 /* Change our root directory */
568 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
569 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
571 if (chdir("/") == -1)
572 fatal("chdir(\"/\"): %s", strerror(errno));
574 /* Drop our privileges */
575 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
578 /* XXX not ready, too heavy after chroot */
579 do_setusercontext(pw);
581 gidset[0] = pw->pw_gid;
582 if (setgroups(1, gidset) < 0)
583 fatal("setgroups: %.100s", strerror(errno));
584 permanently_set_uid(pw);
589 privsep_preauth(Authctxt *authctxt)
594 /* Set up unprivileged child process to deal with network data */
595 pmonitor = monitor_init();
596 /* Store a pointer to the kex for later rekeying */
597 pmonitor->m_pkex = &xxx_kex;
601 fatal("fork of unprivileged child failed");
602 } else if (pid != 0) {
603 debug2("Network child is on pid %ld", (long)pid);
605 close(pmonitor->m_recvfd);
606 pmonitor->m_pid = pid;
607 monitor_child_preauth(authctxt, pmonitor);
608 close(pmonitor->m_sendfd);
611 monitor_sync(pmonitor);
613 /* Wait for the child's exit status */
614 while (waitpid(pid, &status, 0) < 0)
621 close(pmonitor->m_sendfd);
623 /* Demote the child */
624 if (getuid() == 0 || geteuid() == 0)
625 privsep_preauth_child();
626 setproctitle("%s", "[net]");
632 privsep_postauth(Authctxt *authctxt)
634 #ifdef DISABLE_FD_PASSING
637 if (authctxt->pw->pw_uid == 0 || options.use_login) {
639 /* File descriptor passing is broken or root login */
640 monitor_apply_keystate(pmonitor);
645 /* Authentication complete */
647 if (startup_pipe != -1) {
652 /* New socket pair */
653 monitor_reinit(pmonitor);
655 pmonitor->m_pid = fork();
656 if (pmonitor->m_pid == -1)
657 fatal("fork of unprivileged child failed");
658 else if (pmonitor->m_pid != 0) {
659 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
660 close(pmonitor->m_recvfd);
661 buffer_clear(&loginmsg);
662 monitor_child_postauth(pmonitor);
668 close(pmonitor->m_sendfd);
670 /* Demote the private keys to public keys. */
671 demote_sensitive_data();
673 /* Drop privileges */
674 do_setusercontext(authctxt->pw);
676 /* It is safe now to apply the key state */
677 monitor_apply_keystate(pmonitor);
681 list_hostkey_types(void)
689 for (i = 0; i < options.num_host_key_files; i++) {
690 Key *key = sensitive_data.host_keys[i];
696 if (buffer_len(&b) > 0)
697 buffer_append(&b, ",", 1);
698 p = key_ssh_name(key);
699 buffer_append(&b, p, strlen(p));
703 buffer_append(&b, "\0", 1);
704 ret = xstrdup(buffer_ptr(&b));
706 debug("list_hostkey_types: %s", ret);
711 get_hostkey_by_type(int type)
715 for (i = 0; i < options.num_host_key_files; i++) {
716 Key *key = sensitive_data.host_keys[i];
717 if (key != NULL && key->type == type)
724 get_hostkey_by_index(int ind)
726 if (ind < 0 || ind >= options.num_host_key_files)
728 return (sensitive_data.host_keys[ind]);
732 get_hostkey_index(Key *key)
736 for (i = 0; i < options.num_host_key_files; i++) {
737 if (key == sensitive_data.host_keys[i])
744 * returns 1 if connection should be dropped, 0 otherwise.
745 * dropping starts at connection #max_startups_begin with a probability
746 * of (max_startups_rate/100). the probability increases linearly until
747 * all connections are dropped for startups > max_startups
750 drop_connection(int startups)
754 if (startups < options.max_startups_begin)
756 if (startups >= options.max_startups)
758 if (options.max_startups_rate == 100)
761 p = 100 - options.max_startups_rate;
762 p *= startups - options.max_startups_begin;
763 p /= options.max_startups - options.max_startups_begin;
764 p += options.max_startups_rate;
765 r = arc4random() % 100;
767 debug("drop_connection: p %d, r %d", p, r);
768 return (r < p) ? 1 : 0;
774 fprintf(stderr, "%s, %s\n",
775 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
777 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
778 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
784 send_rexec_state(int fd, Buffer *conf)
788 debug3("%s: entering fd = %d config len %d", __func__, fd,
792 * Protocol from reexec master to child:
793 * string configuration
794 * u_int ephemeral_key_follows
795 * bignum e (only if ephemeral_key_follows == 1)
803 buffer_put_cstring(&m, buffer_ptr(conf));
805 if (sensitive_data.server_key != NULL &&
806 sensitive_data.server_key->type == KEY_RSA1) {
807 buffer_put_int(&m, 1);
808 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
809 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
810 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
811 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
812 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
813 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
815 buffer_put_int(&m, 0);
817 if (ssh_msg_send(fd, 0, &m) == -1)
818 fatal("%s: ssh_msg_send failed", __func__);
822 debug3("%s: done", __func__);
826 recv_rexec_state(int fd, Buffer *conf)
832 debug3("%s: entering fd = %d", __func__, fd);
836 if (ssh_msg_recv(fd, &m) == -1)
837 fatal("%s: ssh_msg_recv failed", __func__);
838 if (buffer_get_char(&m) != 0)
839 fatal("%s: rexec version mismatch", __func__);
841 cp = buffer_get_string(&m, &len);
843 buffer_append(conf, cp, len + 1);
846 if (buffer_get_int(&m)) {
847 if (sensitive_data.server_key != NULL)
848 key_free(sensitive_data.server_key);
849 sensitive_data.server_key = key_new_private(KEY_RSA1);
850 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
851 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
852 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
853 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
854 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
855 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
856 rsa_generate_additional_parameters(
857 sensitive_data.server_key->rsa);
861 debug3("%s: done", __func__);
865 * Main program for the daemon.
868 main(int ac, char **av)
872 int opt, j, i, fdsetsz, on = 1;
873 int sock_in = -1, sock_out = -1, newsock = -1;
877 struct sockaddr_storage from;
878 const char *remote_ip;
882 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
884 int listen_sock, maxfd;
885 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
889 int ret, key_used = 0;
892 #ifdef HAVE_SECUREWARE
893 (void)set_auth_parameters(ac, av);
895 __progname = ssh_get_progname(av[0]);
898 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
901 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
902 for (i = 0; i < ac; i++)
903 saved_argv[i] = xstrdup(av[i]);
904 saved_argv[i] = NULL;
906 #ifndef HAVE_SETPROCTITLE
907 /* Prepare for later setproctitle emulation */
908 compat_init_setproctitle(ac, av);
912 if (geteuid() == 0 && setgroups(0, NULL) == -1)
913 debug("setgroups(): %.200s", strerror(errno));
915 /* Initialize configuration options to their default values. */
916 initialize_server_options(&options);
918 /* Parse command-line arguments. */
919 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
922 options.address_family = AF_INET;
925 options.address_family = AF_INET6;
928 config_file_name = optarg;
931 if (debug_flag == 0) {
933 options.log_level = SYSLOG_LEVEL_DEBUG1;
934 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
957 options.log_level = SYSLOG_LEVEL_QUIET;
960 options.server_key_bits = atoi(optarg);
963 options.ports_from_cmdline = 1;
964 if (options.num_ports >= MAX_PORTS) {
965 fprintf(stderr, "too many ports.\n");
968 options.ports[options.num_ports++] = a2port(optarg);
969 if (options.ports[options.num_ports-1] == 0) {
970 fprintf(stderr, "Bad port number.\n");
975 if ((options.login_grace_time = convtime(optarg)) == -1) {
976 fprintf(stderr, "Invalid login grace time.\n");
981 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
982 fprintf(stderr, "Invalid key regeneration interval.\n");
987 if (options.num_host_key_files >= MAX_HOSTKEYS) {
988 fprintf(stderr, "too many host keys.\n");
991 options.host_key_files[options.num_host_key_files++] = optarg;
997 utmp_len = atoi(optarg);
998 if (utmp_len > MAXHOSTNAMELEN) {
999 fprintf(stderr, "Invalid utmp length.\n");
1004 line = xstrdup(optarg);
1005 if (process_server_config_line(&options, line,
1006 "command-line", 0) != 0)
1016 if (rexeced_flag || inetd_flag)
1018 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1019 fatal("sshd re-exec requires execution with an absolute path");
1021 closefrom(REEXEC_MIN_FREE_FD);
1023 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1025 SSLeay_add_all_algorithms();
1028 * Force logging to stderr until we have loaded the private host
1029 * key (unless started from inetd)
1031 log_init(__progname,
1032 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1033 SYSLOG_LEVEL_INFO : options.log_level,
1034 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1035 SYSLOG_FACILITY_AUTH : options.log_facility,
1036 log_stderr || !inetd_flag);
1039 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1040 * root's environment
1042 if (getenv("KRB5CCNAME") != NULL)
1043 unsetenv("KRB5CCNAME");
1046 /* Cray can define user privs drop all privs now!
1047 * Not needed on PRIV_SU systems!
1054 sensitive_data.server_key = NULL;
1055 sensitive_data.ssh1_host_key = NULL;
1056 sensitive_data.have_ssh1_key = 0;
1057 sensitive_data.have_ssh2_key = 0;
1059 /* Fetch our configuration */
1062 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1064 load_server_config(config_file_name, &cfg);
1066 parse_server_config(&options,
1067 rexeced_flag ? "rexec" : config_file_name, &cfg);
1072 /* Fill in default values for those options not explicitly set. */
1073 fill_default_server_options(&options);
1075 /* set default channel AF */
1076 channel_set_af(options.address_family);
1078 /* Check that there are no remaining arguments. */
1080 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1084 debug("sshd version %.100s", SSH_RELEASE);
1086 /* load private host keys */
1087 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1089 for (i = 0; i < options.num_host_key_files; i++)
1090 sensitive_data.host_keys[i] = NULL;
1092 for (i = 0; i < options.num_host_key_files; i++) {
1093 key = key_load_private(options.host_key_files[i], "", NULL);
1094 sensitive_data.host_keys[i] = key;
1096 error("Could not load host key: %s",
1097 options.host_key_files[i]);
1098 sensitive_data.host_keys[i] = NULL;
1101 switch (key->type) {
1103 sensitive_data.ssh1_host_key = key;
1104 sensitive_data.have_ssh1_key = 1;
1108 sensitive_data.have_ssh2_key = 1;
1111 debug("private host key: #%d type %d %s", i, key->type,
1114 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1115 logit("Disabling protocol version 1. Could not load host key");
1116 options.protocol &= ~SSH_PROTO_1;
1118 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1119 logit("Disabling protocol version 2. Could not load host key");
1120 options.protocol &= ~SSH_PROTO_2;
1122 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1123 logit("sshd: no hostkeys available -- exiting.");
1127 /* Check certain values for sanity. */
1128 if (options.protocol & SSH_PROTO_1) {
1129 if (options.server_key_bits < 512 ||
1130 options.server_key_bits > 32768) {
1131 fprintf(stderr, "Bad server key size.\n");
1135 * Check that server and host key lengths differ sufficiently. This
1136 * is necessary to make double encryption work with rsaref. Oh, I
1137 * hate software patents. I dont know if this can go? Niels
1139 if (options.server_key_bits >
1140 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1141 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1142 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1143 SSH_KEY_BITS_RESERVED) {
1144 options.server_key_bits =
1145 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1146 SSH_KEY_BITS_RESERVED;
1147 debug("Forcing server key to %d bits to make it differ from host key.",
1148 options.server_key_bits);
1156 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1157 fatal("Privilege separation user %s does not exist",
1159 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1160 (S_ISDIR(st.st_mode) == 0))
1161 fatal("Missing privilege separation directory: %s",
1162 _PATH_PRIVSEP_CHROOT_DIR);
1165 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1166 (st.st_uid != getuid () ||
1167 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1169 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1171 fatal("%s must be owned by root and not group or "
1172 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1175 /* Configuration looks good, so exit if in test mode. */
1180 * Clear out any supplemental groups we may have inherited. This
1181 * prevents inadvertent creation of files with bad modes (in the
1182 * portable version at least, it's certainly possible for PAM
1183 * to create a file, and we can't control the code in every
1184 * module which might be used).
1186 if (setgroups(0, NULL) < 0)
1187 debug("setgroups() failed: %.200s", strerror(errno));
1190 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1191 for (i = 0; i < rexec_argc; i++) {
1192 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1193 rexec_argv[i] = saved_argv[i];
1195 rexec_argv[rexec_argc] = "-R";
1196 rexec_argv[rexec_argc + 1] = NULL;
1199 /* Initialize the log (it is reinitialized below in case we forked). */
1200 if (debug_flag && (!inetd_flag || rexeced_flag))
1202 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1205 * If not in debugging mode, and not started from inetd, disconnect
1206 * from the controlling terminal, and fork. The original process
1209 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1212 #endif /* TIOCNOTTY */
1213 if (daemon(0, 0) < 0)
1214 fatal("daemon() failed: %.200s", strerror(errno));
1216 /* Disconnect from the controlling tty. */
1218 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1220 (void) ioctl(fd, TIOCNOTTY, NULL);
1223 #endif /* TIOCNOTTY */
1225 /* Reinitialize the log (because of the fork above). */
1226 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1228 /* Initialize the random number generator. */
1231 /* Chdir to the root directory so that the current disk can be
1232 unmounted if desired. */
1235 /* ignore SIGPIPE */
1236 signal(SIGPIPE, SIG_IGN);
1238 /* Start listening for a socket, unless started from inetd. */
1244 close(REEXEC_CONFIG_PASS_FD);
1245 sock_in = sock_out = dup(STDIN_FILENO);
1247 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1248 close(REEXEC_STARTUP_PIPE_FD);
1251 sock_in = dup(STDIN_FILENO);
1252 sock_out = dup(STDOUT_FILENO);
1255 * We intentionally do not close the descriptors 0, 1, and 2
1256 * as our code for setting the descriptors won't work if
1257 * ttyfd happens to be one of those.
1259 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1260 dup2(fd, STDIN_FILENO);
1261 dup2(fd, STDOUT_FILENO);
1262 if (fd > STDOUT_FILENO)
1265 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1266 if ((options.protocol & SSH_PROTO_1) &&
1267 sensitive_data.server_key == NULL)
1268 generate_ephemeral_server_key();
1270 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1271 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1273 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1274 fatal("Too many listen sockets. "
1275 "Enlarge MAX_LISTEN_SOCKS");
1276 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1277 ntop, sizeof(ntop), strport, sizeof(strport),
1278 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1279 error("getnameinfo failed: %.100s",
1280 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1284 /* Create socket for listening. */
1285 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1287 if (listen_sock < 0) {
1288 /* kernel may not support ipv6 */
1289 verbose("socket: %.100s", strerror(errno));
1292 if (set_nonblock(listen_sock) == -1) {
1297 * Set socket options.
1298 * Allow local port reuse in TIME_WAIT.
1300 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1301 &on, sizeof(on)) == -1)
1302 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1304 debug("Bind to port %s on %s.", strport, ntop);
1306 /* Bind the socket to the desired port. */
1307 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1309 error("Bind to port %s on %s failed: %.200s.",
1310 strport, ntop, strerror(errno));
1314 listen_socks[num_listen_socks] = listen_sock;
1317 /* Start listening on the port. */
1318 logit("Server listening on %s port %s.", ntop, strport);
1319 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1320 fatal("listen: %.100s", strerror(errno));
1323 freeaddrinfo(options.listen_addrs);
1325 if (!num_listen_socks)
1326 fatal("Cannot bind any address.");
1328 if (options.protocol & SSH_PROTO_1)
1329 generate_ephemeral_server_key();
1332 * Arrange to restart on SIGHUP. The handler needs
1335 signal(SIGHUP, sighup_handler);
1337 signal(SIGTERM, sigterm_handler);
1338 signal(SIGQUIT, sigterm_handler);
1340 /* Arrange SIGCHLD to be caught. */
1341 signal(SIGCHLD, main_sigchld_handler);
1343 /* Write out the pid file after the sigterm handler is setup */
1346 * Record our pid in /var/run/sshd.pid to make it
1347 * easier to kill the correct sshd. We don't want to
1348 * do this before the bind above because the bind will
1349 * fail if there already is a daemon, and this will
1350 * overwrite any old pid in the file.
1352 f = fopen(options.pid_file, "wb");
1354 error("Couldn't create pid file \"%s\": %s",
1355 options.pid_file, strerror(errno));
1357 fprintf(f, "%ld\n", (long) getpid());
1362 /* setup fd set for listen */
1365 for (i = 0; i < num_listen_socks; i++)
1366 if (listen_socks[i] > maxfd)
1367 maxfd = listen_socks[i];
1368 /* pipes connected to unauthenticated childs */
1369 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1370 for (i = 0; i < options.max_startups; i++)
1371 startup_pipes[i] = -1;
1374 * Stay listening for connections until the system crashes or
1375 * the daemon is killed with a signal.
1378 if (received_sighup)
1382 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1383 fdset = (fd_set *)xmalloc(fdsetsz);
1384 memset(fdset, 0, fdsetsz);
1386 for (i = 0; i < num_listen_socks; i++)
1387 FD_SET(listen_socks[i], fdset);
1388 for (i = 0; i < options.max_startups; i++)
1389 if (startup_pipes[i] != -1)
1390 FD_SET(startup_pipes[i], fdset);
1392 /* Wait in select until there is a connection. */
1393 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1394 if (ret < 0 && errno != EINTR)
1395 error("select: %.100s", strerror(errno));
1396 if (received_sigterm) {
1397 logit("Received signal %d; terminating.",
1398 (int) received_sigterm);
1399 close_listen_socks();
1400 unlink(options.pid_file);
1403 if (key_used && key_do_regen) {
1404 generate_ephemeral_server_key();
1411 for (i = 0; i < options.max_startups; i++)
1412 if (startup_pipes[i] != -1 &&
1413 FD_ISSET(startup_pipes[i], fdset)) {
1415 * the read end of the pipe is ready
1416 * if the child has closed the pipe
1417 * after successful authentication
1418 * or if the child has died
1420 close(startup_pipes[i]);
1421 startup_pipes[i] = -1;
1424 for (i = 0; i < num_listen_socks; i++) {
1425 if (!FD_ISSET(listen_socks[i], fdset))
1427 fromlen = sizeof(from);
1428 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1431 if (errno != EINTR && errno != EWOULDBLOCK)
1432 error("accept: %.100s", strerror(errno));
1435 if (unset_nonblock(newsock) == -1) {
1439 if (drop_connection(startups) == 1) {
1440 debug("drop connection #%d", startups);
1444 if (pipe(startup_p) == -1) {
1449 if (rexec_flag && socketpair(AF_UNIX,
1450 SOCK_STREAM, 0, config_s) == -1) {
1451 error("reexec socketpair: %s",
1454 close(startup_p[0]);
1455 close(startup_p[1]);
1459 for (j = 0; j < options.max_startups; j++)
1460 if (startup_pipes[j] == -1) {
1461 startup_pipes[j] = startup_p[0];
1462 if (maxfd < startup_p[0])
1463 maxfd = startup_p[0];
1469 * Got connection. Fork a child to handle it, unless
1470 * we are in debugging mode.
1474 * In debugging mode. Close the listening
1475 * socket, and start processing the
1476 * connection without forking.
1478 debug("Server will not fork when running in debugging mode.");
1479 close_listen_socks();
1482 close(startup_p[0]);
1483 close(startup_p[1]);
1487 send_rexec_state(config_s[0],
1494 * Normal production daemon. Fork, and have
1495 * the child process the connection. The
1496 * parent continues listening.
1498 if ((pid = fork()) == 0) {
1500 * Child. Close the listening and max_startup
1501 * sockets. Start using the accepted socket.
1502 * Reinitialize logging (since our pid has
1503 * changed). We break out of the loop to handle
1506 startup_pipe = startup_p[1];
1507 close_startup_pipes();
1508 close_listen_socks();
1511 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1518 /* Parent. Stay in the loop. */
1520 error("fork: %.100s", strerror(errno));
1522 debug("Forked child %ld.", (long)pid);
1524 close(startup_p[1]);
1527 send_rexec_state(config_s[0], &cfg);
1532 /* Mark that the key has been used (it was "given" to the child). */
1533 if ((options.protocol & SSH_PROTO_1) &&
1535 /* Schedule server key regeneration alarm. */
1536 signal(SIGALRM, key_regeneration_alarm);
1537 alarm(options.key_regeneration_time);
1543 /* Close the new socket (the child is now taking care of it). */
1546 /* child process check (or debug mode) */
1547 if (num_listen_socks < 0)
1552 /* This is the child processing a new connection. */
1553 setproctitle("%s", "[accepted]");
1556 * Create a new session and process group since the 4.4BSD
1557 * setlogin() affects the entire process group. We don't
1558 * want the child to be able to affect the parent.
1560 #if !defined(SSHD_ACQUIRES_CTTY)
1562 * If setsid is called, on some platforms sshd will later acquire a
1563 * controlling terminal which will result in "could not set
1564 * controlling tty" errors.
1566 if (!debug_flag && !inetd_flag && setsid() < 0)
1567 error("setsid: %.100s", strerror(errno));
1573 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1574 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1575 dup2(newsock, STDIN_FILENO);
1576 dup2(STDIN_FILENO, STDOUT_FILENO);
1577 if (startup_pipe == -1)
1578 close(REEXEC_STARTUP_PIPE_FD);
1580 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1582 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1584 if (startup_pipe != -1)
1585 close(startup_pipe);
1587 execv(rexec_argv[0], rexec_argv);
1589 /* Reexec has failed, fall back and continue */
1590 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1591 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1592 log_init(__progname, options.log_level,
1593 options.log_facility, log_stderr);
1596 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1598 close(REEXEC_CONFIG_PASS_FD);
1599 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1600 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1601 dup2(fd, STDIN_FILENO);
1602 dup2(fd, STDOUT_FILENO);
1603 if (fd > STDERR_FILENO)
1606 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1607 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1611 * Disable the key regeneration alarm. We will not regenerate the
1612 * key since we are no longer in a position to give it to anyone. We
1613 * will not restart on SIGHUP since it no longer makes sense.
1616 signal(SIGALRM, SIG_DFL);
1617 signal(SIGHUP, SIG_DFL);
1618 signal(SIGTERM, SIG_DFL);
1619 signal(SIGQUIT, SIG_DFL);
1620 signal(SIGCHLD, SIG_DFL);
1621 signal(SIGINT, SIG_DFL);
1623 /* Set SO_KEEPALIVE if requested. */
1624 if (options.tcp_keep_alive &&
1625 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1627 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1631 * Initialize the resolver. This may not happen automatically
1632 * before privsep chroot().
1634 if ((_res.options & RES_INIT) == 0) {
1635 debug("res_init()");
1641 * Register our connection. This turns encryption off because we do
1644 packet_set_connection(sock_in, sock_out);
1646 remote_port = get_remote_port();
1647 remote_ip = get_remote_ipaddr();
1649 #ifdef SSH_AUDIT_EVENTS
1650 audit_connection_from(remote_ip, remote_port);
1653 /* Check whether logins are denied from this host. */
1654 if (packet_connection_is_on_socket()) {
1655 struct request_info req;
1657 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1660 if (!hosts_access(&req)) {
1661 debug("Connection refused by tcp wrapper");
1664 fatal("libwrap refuse returns");
1667 #endif /* LIBWRAP */
1669 /* Log the connection. */
1670 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1673 * We don\'t want to listen forever unless the other side
1674 * successfully authenticates itself. So we set up an alarm which is
1675 * cleared after successful authentication. A limit of zero
1676 * indicates no limit. Note that we don\'t set the alarm in debugging
1677 * mode; it is just annoying to have the server exit just when you
1678 * are about to discover the bug.
1680 signal(SIGALRM, grace_alarm_handler);
1682 alarm(options.login_grace_time);
1684 sshd_exchange_identification(sock_in, sock_out);
1686 packet_set_nonblocking();
1688 /* allocate authentication context */
1689 authctxt = xmalloc(sizeof(*authctxt));
1690 memset(authctxt, 0, sizeof(*authctxt));
1692 authctxt->loginmsg = &loginmsg;
1694 /* XXX global for cleanup, access from other modules */
1695 the_authctxt = authctxt;
1697 /* prepare buffer to collect messages to display to user after login */
1698 buffer_init(&loginmsg);
1701 if (privsep_preauth(authctxt) == 1)
1704 /* perform the key exchange */
1705 /* authenticate user and start session */
1708 do_authentication2(authctxt);
1711 do_authentication(authctxt);
1714 * If we use privilege separation, the unprivileged child transfers
1715 * the current keystate and exits
1718 mm_send_keystate(pmonitor);
1723 #ifdef SSH_AUDIT_EVENTS
1724 audit_event(SSH_AUTH_SUCCESS);
1728 * In privilege separation, we fork another child and prepare
1729 * file descriptor passing.
1732 privsep_postauth(authctxt);
1733 /* the monitor process [priv] will not return */
1735 destroy_sensitive_data();
1738 /* Start session. */
1739 do_authenticated(authctxt);
1741 /* The connection has been terminated. */
1742 verbose("Closing connection to %.100s", remote_ip);
1745 if (options.use_pam)
1747 #endif /* USE_PAM */
1749 #ifdef SSH_AUDIT_EVENTS
1750 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1762 * Decrypt session_key_int using our private server key and private host key
1763 * (key with larger modulus first).
1766 ssh1_session_key(BIGNUM *session_key_int)
1770 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1771 /* Server key has bigger modulus. */
1772 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1773 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1774 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1775 get_remote_ipaddr(),
1776 BN_num_bits(sensitive_data.server_key->rsa->n),
1777 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1778 SSH_KEY_BITS_RESERVED);
1780 if (rsa_private_decrypt(session_key_int, session_key_int,
1781 sensitive_data.server_key->rsa) <= 0)
1783 if (rsa_private_decrypt(session_key_int, session_key_int,
1784 sensitive_data.ssh1_host_key->rsa) <= 0)
1787 /* Host key has bigger modulus (or they are equal). */
1788 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1789 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1790 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1791 get_remote_ipaddr(),
1792 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1793 BN_num_bits(sensitive_data.server_key->rsa->n),
1794 SSH_KEY_BITS_RESERVED);
1796 if (rsa_private_decrypt(session_key_int, session_key_int,
1797 sensitive_data.ssh1_host_key->rsa) < 0)
1799 if (rsa_private_decrypt(session_key_int, session_key_int,
1800 sensitive_data.server_key->rsa) < 0)
1813 BIGNUM *session_key_int;
1814 u_char session_key[SSH_SESSION_KEY_LENGTH];
1816 u_int cipher_type, auth_mask, protocol_flags;
1820 * Generate check bytes that the client must send back in the user
1821 * packet in order for it to be accepted; this is used to defy ip
1822 * spoofing attacks. Note that this only works against somebody
1823 * doing IP spoofing from a remote machine; any machine on the local
1824 * network can still see outgoing packets and catch the random
1825 * cookie. This only affects rhosts authentication, and this is one
1826 * of the reasons why it is inherently insecure.
1828 for (i = 0; i < 8; i++) {
1831 cookie[i] = rnd & 0xff;
1836 * Send our public key. We include in the packet 64 bits of random
1837 * data that must be matched in the reply in order to prevent IP
1840 packet_start(SSH_SMSG_PUBLIC_KEY);
1841 for (i = 0; i < 8; i++)
1842 packet_put_char(cookie[i]);
1844 /* Store our public server RSA key. */
1845 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1846 packet_put_bignum(sensitive_data.server_key->rsa->e);
1847 packet_put_bignum(sensitive_data.server_key->rsa->n);
1849 /* Store our public host RSA key. */
1850 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1851 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1852 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1854 /* Put protocol flags. */
1855 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1857 /* Declare which ciphers we support. */
1858 packet_put_int(cipher_mask_ssh1(0));
1860 /* Declare supported authentication types. */
1862 if (options.rhosts_rsa_authentication)
1863 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1864 if (options.rsa_authentication)
1865 auth_mask |= 1 << SSH_AUTH_RSA;
1866 if (options.challenge_response_authentication == 1)
1867 auth_mask |= 1 << SSH_AUTH_TIS;
1868 if (options.password_authentication)
1869 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1870 packet_put_int(auth_mask);
1872 /* Send the packet and wait for it to be sent. */
1874 packet_write_wait();
1876 debug("Sent %d bit server key and %d bit host key.",
1877 BN_num_bits(sensitive_data.server_key->rsa->n),
1878 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1880 /* Read clients reply (cipher type and session key). */
1881 packet_read_expect(SSH_CMSG_SESSION_KEY);
1883 /* Get cipher type and check whether we accept this. */
1884 cipher_type = packet_get_char();
1886 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1887 packet_disconnect("Warning: client selects unsupported cipher.");
1889 /* Get check bytes from the packet. These must match those we
1890 sent earlier with the public key packet. */
1891 for (i = 0; i < 8; i++)
1892 if (cookie[i] != packet_get_char())
1893 packet_disconnect("IP Spoofing check bytes do not match.");
1895 debug("Encryption type: %.200s", cipher_name(cipher_type));
1897 /* Get the encrypted integer. */
1898 if ((session_key_int = BN_new()) == NULL)
1899 fatal("do_ssh1_kex: BN_new failed");
1900 packet_get_bignum(session_key_int);
1902 protocol_flags = packet_get_int();
1903 packet_set_protocol_flags(protocol_flags);
1906 /* Decrypt session_key_int using host/server keys */
1907 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1910 * Extract session key from the decrypted integer. The key is in the
1911 * least significant 256 bits of the integer; the first byte of the
1912 * key is in the highest bits.
1915 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1916 len = BN_num_bytes(session_key_int);
1917 if (len < 0 || len > sizeof(session_key)) {
1918 error("do_connection: bad session key len from %s: "
1919 "session_key_int %d > sizeof(session_key) %lu",
1920 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1923 memset(session_key, 0, sizeof(session_key));
1924 BN_bn2bin(session_key_int,
1925 session_key + sizeof(session_key) - len);
1927 derive_ssh1_session_id(
1928 sensitive_data.ssh1_host_key->rsa->n,
1929 sensitive_data.server_key->rsa->n,
1930 cookie, session_id);
1932 * Xor the first 16 bytes of the session key with the
1935 for (i = 0; i < 16; i++)
1936 session_key[i] ^= session_id[i];
1940 int bytes = BN_num_bytes(session_key_int);
1941 u_char *buf = xmalloc(bytes);
1944 logit("do_connection: generating a fake encryption key");
1945 BN_bn2bin(session_key_int, buf);
1947 MD5_Update(&md, buf, bytes);
1948 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1949 MD5_Final(session_key, &md);
1951 MD5_Update(&md, session_key, 16);
1952 MD5_Update(&md, buf, bytes);
1953 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1954 MD5_Final(session_key + 16, &md);
1955 memset(buf, 0, bytes);
1957 for (i = 0; i < 16; i++)
1958 session_id[i] = session_key[i] ^ session_key[i + 16];
1960 /* Destroy the private and public keys. No longer. */
1961 destroy_sensitive_data();
1964 mm_ssh1_session_id(session_id);
1966 /* Destroy the decrypted integer. It is no longer needed. */
1967 BN_clear_free(session_key_int);
1969 /* Set the session key. From this on all communications will be encrypted. */
1970 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1972 /* Destroy our copy of the session key. It is no longer needed. */
1973 memset(session_key, 0, sizeof(session_key));
1975 debug("Received session key; encryption turned on.");
1977 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1978 packet_start(SSH_SMSG_SUCCESS);
1980 packet_write_wait();
1984 * SSH2 key exchange: diffie-hellman-group1-sha1
1991 if (options.ciphers != NULL) {
1992 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1993 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1995 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1996 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1997 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1998 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2000 if (options.macs != NULL) {
2001 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2002 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2004 if (!options.compression) {
2005 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2006 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2008 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2010 /* start key exchange */
2011 kex = kex_setup(myproposal);
2012 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2013 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2014 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2016 kex->client_version_string=client_version_string;
2017 kex->server_version_string=server_version_string;
2018 kex->load_host_key=&get_hostkey_by_type;
2019 kex->host_key_index=&get_hostkey_index;
2023 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2025 session_id2 = kex->session_id;
2026 session_id2_len = kex->session_id_len;
2029 /* send 1st encrypted/maced/compressed message */
2030 packet_start(SSH2_MSG_IGNORE);
2031 packet_put_cstring("markus");
2033 packet_write_wait();
2038 /* server specific fatal cleanup */
2043 do_cleanup(the_authctxt);
2044 #ifdef SSH_AUDIT_EVENTS
2045 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2046 if (!use_privsep || mm_is_monitor())
2047 audit_event(SSH_CONNECTION_ABANDON);