1 /* $OpenBSD: sshd.c,v 1.335 2006/07/09 15:15:11 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>
62 #include <openssl/dh.h>
63 #include <openssl/bn.h>
64 #include <openssl/md5.h>
65 #include <openssl/rand.h>
66 #ifdef HAVE_SECUREWARE
67 #include <sys/security.h>
88 #include "myproposal.h"
90 #include "pathnames.h"
99 #include "monitor_mm.h"
101 #include "monitor_wrap.h"
102 #include "monitor_fdpass.h"
108 int allow_severity = LOG_INFO;
109 int deny_severity = LOG_WARNING;
117 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
118 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
119 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
120 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
122 extern char *__progname;
124 /* Server configuration options. */
125 ServerOptions options;
127 /* Name of the server configuration file. */
128 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
131 * Debug mode flag. This can be set on the command line. If debug
132 * mode is enabled, extra debugging output will be sent to the system
133 * log, the daemon will not go to background, and will exit after processing
134 * the first connection.
138 /* Flag indicating that the daemon should only test the configuration and keys. */
141 /* Flag indicating that the daemon is being started from inetd. */
144 /* Flag indicating that sshd should not detach and become a daemon. */
145 int no_daemon_flag = 0;
147 /* debug goes to stderr unless inetd_flag is set */
150 /* Saved arguments to main(). */
155 int rexeced_flag = 0;
161 * The sockets that the server is listening; this is used in the SIGHUP
164 #define MAX_LISTEN_SOCKS 16
165 int listen_socks[MAX_LISTEN_SOCKS];
166 int num_listen_socks = 0;
169 * the client's version string, passed by sshd2 in compat mode. if != NULL,
170 * sshd will skip the version-number exchange
172 char *client_version_string = NULL;
173 char *server_version_string = NULL;
175 /* for rekeying XXX fixme */
179 * Any really sensitive data in the application is contained in this
180 * structure. The idea is that this structure could be locked into memory so
181 * that the pages do not get written into swap. However, there are some
182 * problems. The private key contains BIGNUMs, and we do not (in principle)
183 * have access to the internals of them, and locking just the structure is
184 * not very useful. Currently, memory locking is not implemented.
187 Key *server_key; /* ephemeral server key */
188 Key *ssh1_host_key; /* ssh1 host key */
189 Key **host_keys; /* all private host keys */
192 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
196 * Flag indicating whether the RSA server key needs to be regenerated.
197 * Is set in the SIGALRM handler and cleared when the key is regenerated.
199 static volatile sig_atomic_t key_do_regen = 0;
201 /* This is set to true when a signal is received. */
202 static volatile sig_atomic_t received_sighup = 0;
203 static volatile sig_atomic_t received_sigterm = 0;
205 /* session identifier, used by RSA-auth */
206 u_char session_id[16];
209 u_char *session_id2 = NULL;
210 u_int session_id2_len = 0;
212 /* record remote hostname or ip */
213 u_int utmp_len = MAXHOSTNAMELEN;
215 /* options.max_startup sized array of fd ints */
216 int *startup_pipes = NULL;
217 int startup_pipe; /* in child */
219 /* variables used for privilege separation */
221 struct monitor *pmonitor = NULL;
223 /* global authentication context */
224 Authctxt *the_authctxt = NULL;
226 /* message to be displayed after login */
229 /* Prototypes for various functions defined later in this file. */
230 void destroy_sensitive_data(void);
231 void demote_sensitive_data(void);
233 static void do_ssh1_kex(void);
234 static void do_ssh2_kex(void);
237 * Close all listening sockets
240 close_listen_socks(void)
244 for (i = 0; i < num_listen_socks; i++)
245 close(listen_socks[i]);
246 num_listen_socks = -1;
250 close_startup_pipes(void)
255 for (i = 0; i < options.max_startups; i++)
256 if (startup_pipes[i] != -1)
257 close(startup_pipes[i]);
261 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
262 * the effect is to reread the configuration file (and to regenerate
268 sighup_handler(int sig)
270 int save_errno = errno;
273 signal(SIGHUP, sighup_handler);
278 * Called from the main program after receiving SIGHUP.
279 * Restarts the server.
284 logit("Received SIGHUP; restarting.");
285 close_listen_socks();
286 close_startup_pipes();
287 execv(saved_argv[0], saved_argv);
288 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
294 * Generic signal handler for terminating signals in the master daemon.
298 sigterm_handler(int sig)
300 received_sigterm = sig;
304 * SIGCHLD handler. This is called whenever a child dies. This will then
305 * reap any zombies left by exited children.
309 main_sigchld_handler(int sig)
311 int save_errno = errno;
315 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
316 (pid < 0 && errno == EINTR))
319 signal(SIGCHLD, main_sigchld_handler);
324 * Signal handler for the alarm after the login grace period has expired.
328 grace_alarm_handler(int sig)
330 /* XXX no idea how fix this signal handler */
332 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
333 kill(pmonitor->m_pid, SIGALRM);
335 /* Log error and exit. */
336 fatal("Timeout before authentication for %s", get_remote_ipaddr());
340 * Signal handler for the key regeneration alarm. Note that this
341 * alarm only occurs in the daemon waiting for connections, and it does not
342 * do anything with the private key or random state before forking.
343 * Thus there should be no concurrency control/asynchronous execution
347 generate_ephemeral_server_key(void)
352 verbose("Generating %s%d bit RSA key.",
353 sensitive_data.server_key ? "new " : "", options.server_key_bits);
354 if (sensitive_data.server_key != NULL)
355 key_free(sensitive_data.server_key);
356 sensitive_data.server_key = key_generate(KEY_RSA1,
357 options.server_key_bits);
358 verbose("RSA key generation complete.");
360 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
363 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
371 key_regeneration_alarm(int sig)
373 int save_errno = errno;
375 signal(SIGALRM, SIG_DFL);
381 sshd_exchange_identification(int sock_in, int sock_out)
385 int remote_major, remote_minor;
388 char buf[256]; /* Must not be larger than remote_version. */
389 char remote_version[256]; /* Must be at least as big as buf. */
391 if ((options.protocol & SSH_PROTO_1) &&
392 (options.protocol & SSH_PROTO_2)) {
393 major = PROTOCOL_MAJOR_1;
395 } else if (options.protocol & SSH_PROTO_2) {
396 major = PROTOCOL_MAJOR_2;
397 minor = PROTOCOL_MINOR_2;
399 major = PROTOCOL_MAJOR_1;
400 minor = PROTOCOL_MINOR_1;
402 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
403 server_version_string = xstrdup(buf);
405 /* Send our protocol version identification. */
406 if (atomicio(vwrite, sock_out, server_version_string,
407 strlen(server_version_string))
408 != strlen(server_version_string)) {
409 logit("Could not write ident string to %s", get_remote_ipaddr());
413 /* Read other sides version identification. */
414 memset(buf, 0, sizeof(buf));
415 for (i = 0; i < sizeof(buf) - 1; i++) {
416 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
417 logit("Did not receive identification string from %s",
418 get_remote_ipaddr());
421 if (buf[i] == '\r') {
423 /* Kludge for F-Secure Macintosh < 1.0.2 */
425 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
429 if (buf[i] == '\n') {
434 buf[sizeof(buf) - 1] = 0;
435 client_version_string = xstrdup(buf);
438 * Check that the versions match. In future this might accept
439 * several versions and set appropriate flags to handle them.
441 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
442 &remote_major, &remote_minor, remote_version) != 3) {
443 s = "Protocol mismatch.\n";
444 (void) atomicio(vwrite, sock_out, s, strlen(s));
447 logit("Bad protocol version identification '%.100s' from %s",
448 client_version_string, get_remote_ipaddr());
451 debug("Client protocol version %d.%d; client software version %.100s",
452 remote_major, remote_minor, remote_version);
454 compat_datafellows(remote_version);
456 if (datafellows & SSH_BUG_PROBE) {
457 logit("probed from %s with %s. Don't panic.",
458 get_remote_ipaddr(), client_version_string);
462 if (datafellows & SSH_BUG_SCANNER) {
463 logit("scanned from %s with %s. Don't panic.",
464 get_remote_ipaddr(), client_version_string);
469 switch (remote_major) {
471 if (remote_minor == 99) {
472 if (options.protocol & SSH_PROTO_2)
478 if (!(options.protocol & SSH_PROTO_1)) {
482 if (remote_minor < 3) {
483 packet_disconnect("Your ssh version is too old and "
484 "is no longer supported. Please install a newer version.");
485 } else if (remote_minor == 3) {
486 /* note that this disables agent-forwarding */
491 if (options.protocol & SSH_PROTO_2) {
500 chop(server_version_string);
501 debug("Local version string %.200s", server_version_string);
504 s = "Protocol major versions differ.\n";
505 (void) atomicio(vwrite, sock_out, s, strlen(s));
508 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
510 server_version_string, client_version_string);
515 /* Destroy the host and server keys. They will no longer be needed. */
517 destroy_sensitive_data(void)
521 if (sensitive_data.server_key) {
522 key_free(sensitive_data.server_key);
523 sensitive_data.server_key = NULL;
525 for (i = 0; i < options.num_host_key_files; i++) {
526 if (sensitive_data.host_keys[i]) {
527 key_free(sensitive_data.host_keys[i]);
528 sensitive_data.host_keys[i] = NULL;
531 sensitive_data.ssh1_host_key = NULL;
532 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
535 /* Demote private to public keys for network child */
537 demote_sensitive_data(void)
542 if (sensitive_data.server_key) {
543 tmp = key_demote(sensitive_data.server_key);
544 key_free(sensitive_data.server_key);
545 sensitive_data.server_key = tmp;
548 for (i = 0; i < options.num_host_key_files; i++) {
549 if (sensitive_data.host_keys[i]) {
550 tmp = key_demote(sensitive_data.host_keys[i]);
551 key_free(sensitive_data.host_keys[i]);
552 sensitive_data.host_keys[i] = tmp;
553 if (tmp->type == KEY_RSA1)
554 sensitive_data.ssh1_host_key = tmp;
558 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
562 privsep_preauth_child(void)
569 /* Enable challenge-response authentication for privilege separation */
570 privsep_challenge_enable();
572 for (i = 0; i < 256; i++)
573 rnd[i] = arc4random();
574 RAND_seed(rnd, sizeof(rnd));
576 /* Demote the private keys to public keys. */
577 demote_sensitive_data();
579 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
580 fatal("Privilege separation user %s does not exist",
582 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
585 /* Change our root directory */
586 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
587 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
589 if (chdir("/") == -1)
590 fatal("chdir(\"/\"): %s", strerror(errno));
592 /* Drop our privileges */
593 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
596 /* XXX not ready, too heavy after chroot */
597 do_setusercontext(pw);
599 gidset[0] = pw->pw_gid;
600 if (setgroups(1, gidset) < 0)
601 fatal("setgroups: %.100s", strerror(errno));
602 permanently_set_uid(pw);
607 privsep_preauth(Authctxt *authctxt)
612 /* Set up unprivileged child process to deal with network data */
613 pmonitor = monitor_init();
614 /* Store a pointer to the kex for later rekeying */
615 pmonitor->m_pkex = &xxx_kex;
619 fatal("fork of unprivileged child failed");
620 } else if (pid != 0) {
621 debug2("Network child is on pid %ld", (long)pid);
623 close(pmonitor->m_recvfd);
624 pmonitor->m_pid = pid;
625 monitor_child_preauth(authctxt, pmonitor);
626 close(pmonitor->m_sendfd);
629 monitor_sync(pmonitor);
631 /* Wait for the child's exit status */
632 while (waitpid(pid, &status, 0) < 0)
639 close(pmonitor->m_sendfd);
641 /* Demote the child */
642 if (getuid() == 0 || geteuid() == 0)
643 privsep_preauth_child();
644 setproctitle("%s", "[net]");
650 privsep_postauth(Authctxt *authctxt)
652 #ifdef DISABLE_FD_PASSING
655 if (authctxt->pw->pw_uid == 0 || options.use_login) {
657 /* File descriptor passing is broken or root login */
662 /* New socket pair */
663 monitor_reinit(pmonitor);
665 pmonitor->m_pid = fork();
666 if (pmonitor->m_pid == -1)
667 fatal("fork of unprivileged child failed");
668 else if (pmonitor->m_pid != 0) {
669 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
670 close(pmonitor->m_recvfd);
671 buffer_clear(&loginmsg);
672 monitor_child_postauth(pmonitor);
678 close(pmonitor->m_sendfd);
680 /* Demote the private keys to public keys. */
681 demote_sensitive_data();
683 /* Drop privileges */
684 do_setusercontext(authctxt->pw);
687 /* It is safe now to apply the key state */
688 monitor_apply_keystate(pmonitor);
691 * Tell the packet layer that authentication was successful, since
692 * this information is not part of the key state.
694 packet_set_authenticated();
698 list_hostkey_types(void)
706 for (i = 0; i < options.num_host_key_files; i++) {
707 Key *key = sensitive_data.host_keys[i];
713 if (buffer_len(&b) > 0)
714 buffer_append(&b, ",", 1);
715 p = key_ssh_name(key);
716 buffer_append(&b, p, strlen(p));
720 buffer_append(&b, "\0", 1);
721 ret = xstrdup(buffer_ptr(&b));
723 debug("list_hostkey_types: %s", ret);
728 get_hostkey_by_type(int type)
732 for (i = 0; i < options.num_host_key_files; i++) {
733 Key *key = sensitive_data.host_keys[i];
734 if (key != NULL && key->type == type)
741 get_hostkey_by_index(int ind)
743 if (ind < 0 || ind >= options.num_host_key_files)
745 return (sensitive_data.host_keys[ind]);
749 get_hostkey_index(Key *key)
753 for (i = 0; i < options.num_host_key_files; i++) {
754 if (key == sensitive_data.host_keys[i])
761 * returns 1 if connection should be dropped, 0 otherwise.
762 * dropping starts at connection #max_startups_begin with a probability
763 * of (max_startups_rate/100). the probability increases linearly until
764 * all connections are dropped for startups > max_startups
767 drop_connection(int startups)
771 if (startups < options.max_startups_begin)
773 if (startups >= options.max_startups)
775 if (options.max_startups_rate == 100)
778 p = 100 - options.max_startups_rate;
779 p *= startups - options.max_startups_begin;
780 p /= options.max_startups - options.max_startups_begin;
781 p += options.max_startups_rate;
782 r = arc4random() % 100;
784 debug("drop_connection: p %d, r %d", p, r);
785 return (r < p) ? 1 : 0;
791 fprintf(stderr, "%s, %s\n",
792 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
794 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
795 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
801 send_rexec_state(int fd, Buffer *conf)
805 debug3("%s: entering fd = %d config len %d", __func__, fd,
809 * Protocol from reexec master to child:
810 * string configuration
811 * u_int ephemeral_key_follows
812 * bignum e (only if ephemeral_key_follows == 1)
818 * string rngseed (only if OpenSSL is not self-seeded)
821 buffer_put_cstring(&m, buffer_ptr(conf));
823 if (sensitive_data.server_key != NULL &&
824 sensitive_data.server_key->type == KEY_RSA1) {
825 buffer_put_int(&m, 1);
826 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
827 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
828 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
829 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
830 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
831 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
833 buffer_put_int(&m, 0);
835 #ifndef OPENSSL_PRNG_ONLY
836 rexec_send_rng_seed(&m);
839 if (ssh_msg_send(fd, 0, &m) == -1)
840 fatal("%s: ssh_msg_send failed", __func__);
844 debug3("%s: done", __func__);
848 recv_rexec_state(int fd, Buffer *conf)
854 debug3("%s: entering fd = %d", __func__, fd);
858 if (ssh_msg_recv(fd, &m) == -1)
859 fatal("%s: ssh_msg_recv failed", __func__);
860 if (buffer_get_char(&m) != 0)
861 fatal("%s: rexec version mismatch", __func__);
863 cp = buffer_get_string(&m, &len);
865 buffer_append(conf, cp, len + 1);
868 if (buffer_get_int(&m)) {
869 if (sensitive_data.server_key != NULL)
870 key_free(sensitive_data.server_key);
871 sensitive_data.server_key = key_new_private(KEY_RSA1);
872 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
873 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
874 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
875 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
876 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
877 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
878 rsa_generate_additional_parameters(
879 sensitive_data.server_key->rsa);
882 #ifndef OPENSSL_PRNG_ONLY
883 rexec_recv_rng_seed(&m);
888 debug3("%s: done", __func__);
892 * Main program for the daemon.
895 main(int ac, char **av)
899 int opt, j, i, on = 1;
900 int sock_in = -1, sock_out = -1, newsock = -1;
904 struct sockaddr_storage from;
905 const char *remote_ip;
909 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
911 int listen_sock, maxfd;
912 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
916 int ret, key_used = 0;
919 #ifdef HAVE_SECUREWARE
920 (void)set_auth_parameters(ac, av);
922 __progname = ssh_get_progname(av[0]);
925 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
928 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
929 for (i = 0; i < ac; i++)
930 saved_argv[i] = xstrdup(av[i]);
931 saved_argv[i] = NULL;
933 #ifndef HAVE_SETPROCTITLE
934 /* Prepare for later setproctitle emulation */
935 compat_init_setproctitle(ac, av);
939 if (geteuid() == 0 && setgroups(0, NULL) == -1)
940 debug("setgroups(): %.200s", strerror(errno));
942 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
945 /* Initialize configuration options to their default values. */
946 initialize_server_options(&options);
948 /* Parse command-line arguments. */
949 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
952 options.address_family = AF_INET;
955 options.address_family = AF_INET6;
958 config_file_name = optarg;
961 if (debug_flag == 0) {
963 options.log_level = SYSLOG_LEVEL_DEBUG1;
964 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
987 options.log_level = SYSLOG_LEVEL_QUIET;
990 options.server_key_bits = (int)strtonum(optarg, 256,
994 options.ports_from_cmdline = 1;
995 if (options.num_ports >= MAX_PORTS) {
996 fprintf(stderr, "too many ports.\n");
999 options.ports[options.num_ports++] = a2port(optarg);
1000 if (options.ports[options.num_ports-1] == 0) {
1001 fprintf(stderr, "Bad port number.\n");
1006 if ((options.login_grace_time = convtime(optarg)) == -1) {
1007 fprintf(stderr, "Invalid login grace time.\n");
1012 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1013 fprintf(stderr, "Invalid key regeneration interval.\n");
1018 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1019 fprintf(stderr, "too many host keys.\n");
1022 options.host_key_files[options.num_host_key_files++] = optarg;
1028 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1029 if (utmp_len > MAXHOSTNAMELEN) {
1030 fprintf(stderr, "Invalid utmp length.\n");
1035 line = xstrdup(optarg);
1036 if (process_server_config_line(&options, line,
1037 "command-line", 0) != 0)
1047 if (rexeced_flag || inetd_flag)
1049 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1050 fatal("sshd re-exec requires execution with an absolute path");
1052 closefrom(REEXEC_MIN_FREE_FD);
1054 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1056 SSLeay_add_all_algorithms();
1059 * Force logging to stderr until we have loaded the private host
1060 * key (unless started from inetd)
1062 log_init(__progname,
1063 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1064 SYSLOG_LEVEL_INFO : options.log_level,
1065 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1066 SYSLOG_FACILITY_AUTH : options.log_facility,
1067 log_stderr || !inetd_flag);
1070 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1071 * root's environment
1073 if (getenv("KRB5CCNAME") != NULL)
1074 unsetenv("KRB5CCNAME");
1077 /* Cray can define user privs drop all privs now!
1078 * Not needed on PRIV_SU systems!
1083 sensitive_data.server_key = NULL;
1084 sensitive_data.ssh1_host_key = NULL;
1085 sensitive_data.have_ssh1_key = 0;
1086 sensitive_data.have_ssh2_key = 0;
1088 /* Fetch our configuration */
1091 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1093 load_server_config(config_file_name, &cfg);
1095 parse_server_config(&options,
1096 rexeced_flag ? "rexec" : config_file_name, &cfg);
1103 /* Fill in default values for those options not explicitly set. */
1104 fill_default_server_options(&options);
1106 /* set default channel AF */
1107 channel_set_af(options.address_family);
1109 /* Check that there are no remaining arguments. */
1111 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1115 debug("sshd version %.100s", SSH_RELEASE);
1117 /* load private host keys */
1118 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1120 for (i = 0; i < options.num_host_key_files; i++)
1121 sensitive_data.host_keys[i] = NULL;
1123 for (i = 0; i < options.num_host_key_files; i++) {
1124 key = key_load_private(options.host_key_files[i], "", NULL);
1125 sensitive_data.host_keys[i] = key;
1127 error("Could not load host key: %s",
1128 options.host_key_files[i]);
1129 sensitive_data.host_keys[i] = NULL;
1132 switch (key->type) {
1134 sensitive_data.ssh1_host_key = key;
1135 sensitive_data.have_ssh1_key = 1;
1139 sensitive_data.have_ssh2_key = 1;
1142 debug("private host key: #%d type %d %s", i, key->type,
1145 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1146 logit("Disabling protocol version 1. Could not load host key");
1147 options.protocol &= ~SSH_PROTO_1;
1149 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1150 logit("Disabling protocol version 2. Could not load host key");
1151 options.protocol &= ~SSH_PROTO_2;
1153 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1154 logit("sshd: no hostkeys available -- exiting.");
1158 /* Check certain values for sanity. */
1159 if (options.protocol & SSH_PROTO_1) {
1160 if (options.server_key_bits < 512 ||
1161 options.server_key_bits > 32768) {
1162 fprintf(stderr, "Bad server key size.\n");
1166 * Check that server and host key lengths differ sufficiently. This
1167 * is necessary to make double encryption work with rsaref. Oh, I
1168 * hate software patents. I dont know if this can go? Niels
1170 if (options.server_key_bits >
1171 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1172 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1173 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1174 SSH_KEY_BITS_RESERVED) {
1175 options.server_key_bits =
1176 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1177 SSH_KEY_BITS_RESERVED;
1178 debug("Forcing server key to %d bits to make it differ from host key.",
1179 options.server_key_bits);
1186 if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1187 fatal("Privilege separation user %s does not exist",
1189 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1190 (S_ISDIR(st.st_mode) == 0))
1191 fatal("Missing privilege separation directory: %s",
1192 _PATH_PRIVSEP_CHROOT_DIR);
1195 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1196 (st.st_uid != getuid () ||
1197 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1199 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1201 fatal("%s must be owned by root and not group or "
1202 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1205 /* Configuration looks good, so exit if in test mode. */
1210 * Clear out any supplemental groups we may have inherited. This
1211 * prevents inadvertent creation of files with bad modes (in the
1212 * portable version at least, it's certainly possible for PAM
1213 * to create a file, and we can't control the code in every
1214 * module which might be used).
1216 if (setgroups(0, NULL) < 0)
1217 debug("setgroups() failed: %.200s", strerror(errno));
1220 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1221 for (i = 0; i < rexec_argc; i++) {
1222 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1223 rexec_argv[i] = saved_argv[i];
1225 rexec_argv[rexec_argc] = "-R";
1226 rexec_argv[rexec_argc + 1] = NULL;
1229 /* Initialize the log (it is reinitialized below in case we forked). */
1230 if (debug_flag && (!inetd_flag || rexeced_flag))
1232 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1235 * If not in debugging mode, and not started from inetd, disconnect
1236 * from the controlling terminal, and fork. The original process
1239 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1242 #endif /* TIOCNOTTY */
1243 if (daemon(0, 0) < 0)
1244 fatal("daemon() failed: %.200s", strerror(errno));
1246 /* Disconnect from the controlling tty. */
1248 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1250 (void) ioctl(fd, TIOCNOTTY, NULL);
1253 #endif /* TIOCNOTTY */
1255 /* Reinitialize the log (because of the fork above). */
1256 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1258 /* Initialize the random number generator. */
1261 /* Chdir to the root directory so that the current disk can be
1262 unmounted if desired. */
1265 /* ignore SIGPIPE */
1266 signal(SIGPIPE, SIG_IGN);
1268 /* Start listening for a socket, unless started from inetd. */
1274 close(REEXEC_CONFIG_PASS_FD);
1275 sock_in = sock_out = dup(STDIN_FILENO);
1277 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1278 close(REEXEC_STARTUP_PIPE_FD);
1281 sock_in = dup(STDIN_FILENO);
1282 sock_out = dup(STDOUT_FILENO);
1285 * We intentionally do not close the descriptors 0, 1, and 2
1286 * as our code for setting the descriptors won't work if
1287 * ttyfd happens to be one of those.
1289 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1290 dup2(fd, STDIN_FILENO);
1291 dup2(fd, STDOUT_FILENO);
1292 if (fd > STDOUT_FILENO)
1295 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1296 if ((options.protocol & SSH_PROTO_1) &&
1297 sensitive_data.server_key == NULL)
1298 generate_ephemeral_server_key();
1300 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1301 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1303 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1304 fatal("Too many listen sockets. "
1305 "Enlarge MAX_LISTEN_SOCKS");
1306 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1307 ntop, sizeof(ntop), strport, sizeof(strport),
1308 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1309 error("getnameinfo failed: %.100s",
1310 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1314 /* Create socket for listening. */
1315 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1317 if (listen_sock < 0) {
1318 /* kernel may not support ipv6 */
1319 verbose("socket: %.100s", strerror(errno));
1322 if (set_nonblock(listen_sock) == -1) {
1327 * Set socket options.
1328 * Allow local port reuse in TIME_WAIT.
1330 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1331 &on, sizeof(on)) == -1)
1332 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1334 debug("Bind to port %s on %s.", strport, ntop);
1336 /* Bind the socket to the desired port. */
1337 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1339 error("Bind to port %s on %s failed: %.200s.",
1340 strport, ntop, strerror(errno));
1344 listen_socks[num_listen_socks] = listen_sock;
1347 /* Start listening on the port. */
1348 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1349 fatal("listen on [%s]:%s: %.100s",
1350 ntop, strport, strerror(errno));
1351 logit("Server listening on %s port %s.", ntop, strport);
1353 freeaddrinfo(options.listen_addrs);
1355 if (!num_listen_socks)
1356 fatal("Cannot bind any address.");
1358 if (options.protocol & SSH_PROTO_1)
1359 generate_ephemeral_server_key();
1362 * Arrange to restart on SIGHUP. The handler needs
1365 signal(SIGHUP, sighup_handler);
1367 signal(SIGTERM, sigterm_handler);
1368 signal(SIGQUIT, sigterm_handler);
1370 /* Arrange SIGCHLD to be caught. */
1371 signal(SIGCHLD, main_sigchld_handler);
1373 /* Write out the pid file after the sigterm handler is setup */
1376 * Record our pid in /var/run/sshd.pid to make it
1377 * easier to kill the correct sshd. We don't want to
1378 * do this before the bind above because the bind will
1379 * fail if there already is a daemon, and this will
1380 * overwrite any old pid in the file.
1382 f = fopen(options.pid_file, "wb");
1384 error("Couldn't create pid file \"%s\": %s",
1385 options.pid_file, strerror(errno));
1387 fprintf(f, "%ld\n", (long) getpid());
1392 /* setup fd set for listen */
1395 for (i = 0; i < num_listen_socks; i++)
1396 if (listen_socks[i] > maxfd)
1397 maxfd = listen_socks[i];
1398 /* pipes connected to unauthenticated childs */
1399 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1400 for (i = 0; i < options.max_startups; i++)
1401 startup_pipes[i] = -1;
1404 * Stay listening for connections until the system crashes or
1405 * the daemon is killed with a signal.
1408 if (received_sighup)
1412 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1415 for (i = 0; i < num_listen_socks; i++)
1416 FD_SET(listen_socks[i], fdset);
1417 for (i = 0; i < options.max_startups; i++)
1418 if (startup_pipes[i] != -1)
1419 FD_SET(startup_pipes[i], fdset);
1421 /* Wait in select until there is a connection. */
1422 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1423 if (ret < 0 && errno != EINTR)
1424 error("select: %.100s", strerror(errno));
1425 if (received_sigterm) {
1426 logit("Received signal %d; terminating.",
1427 (int) received_sigterm);
1428 close_listen_socks();
1429 unlink(options.pid_file);
1432 if (key_used && key_do_regen) {
1433 generate_ephemeral_server_key();
1440 for (i = 0; i < options.max_startups; i++)
1441 if (startup_pipes[i] != -1 &&
1442 FD_ISSET(startup_pipes[i], fdset)) {
1444 * the read end of the pipe is ready
1445 * if the child has closed the pipe
1446 * after successful authentication
1447 * or if the child has died
1449 close(startup_pipes[i]);
1450 startup_pipes[i] = -1;
1453 for (i = 0; i < num_listen_socks; i++) {
1454 if (!FD_ISSET(listen_socks[i], fdset))
1456 fromlen = sizeof(from);
1457 newsock = accept(listen_socks[i],
1458 (struct sockaddr *)&from, &fromlen);
1460 if (errno != EINTR && errno != EWOULDBLOCK)
1461 error("accept: %.100s", strerror(errno));
1464 if (unset_nonblock(newsock) == -1) {
1468 if (drop_connection(startups) == 1) {
1469 debug("drop connection #%d", startups);
1473 if (pipe(startup_p) == -1) {
1478 if (rexec_flag && socketpair(AF_UNIX,
1479 SOCK_STREAM, 0, config_s) == -1) {
1480 error("reexec socketpair: %s",
1483 close(startup_p[0]);
1484 close(startup_p[1]);
1488 for (j = 0; j < options.max_startups; j++)
1489 if (startup_pipes[j] == -1) {
1490 startup_pipes[j] = startup_p[0];
1491 if (maxfd < startup_p[0])
1492 maxfd = startup_p[0];
1498 * Got connection. Fork a child to handle it, unless
1499 * we are in debugging mode.
1503 * In debugging mode. Close the listening
1504 * socket, and start processing the
1505 * connection without forking.
1507 debug("Server will not fork when running in debugging mode.");
1508 close_listen_socks();
1511 close(startup_p[0]);
1512 close(startup_p[1]);
1516 send_rexec_state(config_s[0],
1523 * Normal production daemon. Fork, and have
1524 * the child process the connection. The
1525 * parent continues listening.
1527 if ((pid = fork()) == 0) {
1529 * Child. Close the listening and
1530 * max_startup sockets. Start using
1531 * the accepted socket. Reinitialize
1532 * logging (since our pid has changed).
1533 * We break out of the loop to handle
1536 startup_pipe = startup_p[1];
1537 close_startup_pipes();
1538 close_listen_socks();
1541 log_init(__progname,
1543 options.log_facility,
1551 /* Parent. Stay in the loop. */
1553 error("fork: %.100s", strerror(errno));
1555 debug("Forked child %ld.", (long)pid);
1557 close(startup_p[1]);
1560 send_rexec_state(config_s[0], &cfg);
1566 * Mark that the key has been used (it
1567 * was "given" to the child).
1569 if ((options.protocol & SSH_PROTO_1) &&
1571 /* Schedule server key regeneration alarm. */
1572 signal(SIGALRM, key_regeneration_alarm);
1573 alarm(options.key_regeneration_time);
1580 /* child process check (or debug mode) */
1581 if (num_listen_socks < 0)
1586 /* This is the child processing a new connection. */
1587 setproctitle("%s", "[accepted]");
1590 * Create a new session and process group since the 4.4BSD
1591 * setlogin() affects the entire process group. We don't
1592 * want the child to be able to affect the parent.
1594 #if !defined(SSHD_ACQUIRES_CTTY)
1596 * If setsid is called, on some platforms sshd will later acquire a
1597 * controlling terminal which will result in "could not set
1598 * controlling tty" errors.
1600 if (!debug_flag && !inetd_flag && setsid() < 0)
1601 error("setsid: %.100s", strerror(errno));
1607 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1608 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1609 dup2(newsock, STDIN_FILENO);
1610 dup2(STDIN_FILENO, STDOUT_FILENO);
1611 if (startup_pipe == -1)
1612 close(REEXEC_STARTUP_PIPE_FD);
1614 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1616 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1618 if (startup_pipe != -1)
1619 close(startup_pipe);
1621 execv(rexec_argv[0], rexec_argv);
1623 /* Reexec has failed, fall back and continue */
1624 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1625 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1626 log_init(__progname, options.log_level,
1627 options.log_facility, log_stderr);
1630 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1632 close(REEXEC_CONFIG_PASS_FD);
1633 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1634 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1635 dup2(fd, STDIN_FILENO);
1636 dup2(fd, STDOUT_FILENO);
1637 if (fd > STDERR_FILENO)
1640 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1641 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1645 * Disable the key regeneration alarm. We will not regenerate the
1646 * key since we are no longer in a position to give it to anyone. We
1647 * will not restart on SIGHUP since it no longer makes sense.
1650 signal(SIGALRM, SIG_DFL);
1651 signal(SIGHUP, SIG_DFL);
1652 signal(SIGTERM, SIG_DFL);
1653 signal(SIGQUIT, SIG_DFL);
1654 signal(SIGCHLD, SIG_DFL);
1655 signal(SIGINT, SIG_DFL);
1658 * Register our connection. This turns encryption off because we do
1661 packet_set_connection(sock_in, sock_out);
1662 packet_set_server();
1664 /* Set SO_KEEPALIVE if requested. */
1665 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1666 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1667 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1669 if ((remote_port = get_remote_port()) < 0) {
1670 debug("get_remote_port failed");
1675 * We use get_canonical_hostname with usedns = 0 instead of
1676 * get_remote_ipaddr here so IP options will be checked.
1678 (void) get_canonical_hostname(0);
1680 * The rest of the code depends on the fact that
1681 * get_remote_ipaddr() caches the remote ip, even if
1682 * the socket goes away.
1684 remote_ip = get_remote_ipaddr();
1686 #ifdef SSH_AUDIT_EVENTS
1687 audit_connection_from(remote_ip, remote_port);
1690 /* Check whether logins are denied from this host. */
1691 if (packet_connection_is_on_socket()) {
1692 struct request_info req;
1694 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1697 if (!hosts_access(&req)) {
1698 debug("Connection refused by tcp wrapper");
1701 fatal("libwrap refuse returns");
1704 #endif /* LIBWRAP */
1706 /* Log the connection. */
1707 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1710 * We don't want to listen forever unless the other side
1711 * successfully authenticates itself. So we set up an alarm which is
1712 * cleared after successful authentication. A limit of zero
1713 * indicates no limit. Note that we don't set the alarm in debugging
1714 * mode; it is just annoying to have the server exit just when you
1715 * are about to discover the bug.
1717 signal(SIGALRM, grace_alarm_handler);
1719 alarm(options.login_grace_time);
1721 sshd_exchange_identification(sock_in, sock_out);
1723 packet_set_nonblocking();
1725 /* allocate authentication context */
1726 authctxt = xcalloc(1, sizeof(*authctxt));
1728 authctxt->loginmsg = &loginmsg;
1730 /* XXX global for cleanup, access from other modules */
1731 the_authctxt = authctxt;
1733 /* prepare buffer to collect messages to display to user after login */
1734 buffer_init(&loginmsg);
1737 if (privsep_preauth(authctxt) == 1)
1740 /* perform the key exchange */
1741 /* authenticate user and start session */
1744 do_authentication2(authctxt);
1747 do_authentication(authctxt);
1750 * If we use privilege separation, the unprivileged child transfers
1751 * the current keystate and exits
1754 mm_send_keystate(pmonitor);
1760 * Cancel the alarm we set to limit the time taken for
1764 signal(SIGALRM, SIG_DFL);
1765 if (startup_pipe != -1) {
1766 close(startup_pipe);
1770 #ifdef SSH_AUDIT_EVENTS
1771 audit_event(SSH_AUTH_SUCCESS);
1775 * In privilege separation, we fork another child and prepare
1776 * file descriptor passing.
1779 privsep_postauth(authctxt);
1780 /* the monitor process [priv] will not return */
1782 destroy_sensitive_data();
1785 /* Start session. */
1786 do_authenticated(authctxt);
1788 /* The connection has been terminated. */
1789 verbose("Closing connection to %.100s", remote_ip);
1792 if (options.use_pam)
1794 #endif /* USE_PAM */
1796 #ifdef SSH_AUDIT_EVENTS
1797 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1809 * Decrypt session_key_int using our private server key and private host key
1810 * (key with larger modulus first).
1813 ssh1_session_key(BIGNUM *session_key_int)
1817 if (BN_cmp(sensitive_data.server_key->rsa->n,
1818 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1819 /* Server key has bigger modulus. */
1820 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1821 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1822 SSH_KEY_BITS_RESERVED) {
1823 fatal("do_connection: %s: "
1824 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1825 get_remote_ipaddr(),
1826 BN_num_bits(sensitive_data.server_key->rsa->n),
1827 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1828 SSH_KEY_BITS_RESERVED);
1830 if (rsa_private_decrypt(session_key_int, session_key_int,
1831 sensitive_data.server_key->rsa) <= 0)
1833 if (rsa_private_decrypt(session_key_int, session_key_int,
1834 sensitive_data.ssh1_host_key->rsa) <= 0)
1837 /* Host key has bigger modulus (or they are equal). */
1838 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1839 BN_num_bits(sensitive_data.server_key->rsa->n) +
1840 SSH_KEY_BITS_RESERVED) {
1841 fatal("do_connection: %s: "
1842 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1843 get_remote_ipaddr(),
1844 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1845 BN_num_bits(sensitive_data.server_key->rsa->n),
1846 SSH_KEY_BITS_RESERVED);
1848 if (rsa_private_decrypt(session_key_int, session_key_int,
1849 sensitive_data.ssh1_host_key->rsa) < 0)
1851 if (rsa_private_decrypt(session_key_int, session_key_int,
1852 sensitive_data.server_key->rsa) < 0)
1865 BIGNUM *session_key_int;
1866 u_char session_key[SSH_SESSION_KEY_LENGTH];
1868 u_int cipher_type, auth_mask, protocol_flags;
1872 * Generate check bytes that the client must send back in the user
1873 * packet in order for it to be accepted; this is used to defy ip
1874 * spoofing attacks. Note that this only works against somebody
1875 * doing IP spoofing from a remote machine; any machine on the local
1876 * network can still see outgoing packets and catch the random
1877 * cookie. This only affects rhosts authentication, and this is one
1878 * of the reasons why it is inherently insecure.
1880 for (i = 0; i < 8; i++) {
1883 cookie[i] = rnd & 0xff;
1888 * Send our public key. We include in the packet 64 bits of random
1889 * data that must be matched in the reply in order to prevent IP
1892 packet_start(SSH_SMSG_PUBLIC_KEY);
1893 for (i = 0; i < 8; i++)
1894 packet_put_char(cookie[i]);
1896 /* Store our public server RSA key. */
1897 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1898 packet_put_bignum(sensitive_data.server_key->rsa->e);
1899 packet_put_bignum(sensitive_data.server_key->rsa->n);
1901 /* Store our public host RSA key. */
1902 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1903 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1904 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1906 /* Put protocol flags. */
1907 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1909 /* Declare which ciphers we support. */
1910 packet_put_int(cipher_mask_ssh1(0));
1912 /* Declare supported authentication types. */
1914 if (options.rhosts_rsa_authentication)
1915 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1916 if (options.rsa_authentication)
1917 auth_mask |= 1 << SSH_AUTH_RSA;
1918 if (options.challenge_response_authentication == 1)
1919 auth_mask |= 1 << SSH_AUTH_TIS;
1920 if (options.password_authentication)
1921 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1922 packet_put_int(auth_mask);
1924 /* Send the packet and wait for it to be sent. */
1926 packet_write_wait();
1928 debug("Sent %d bit server key and %d bit host key.",
1929 BN_num_bits(sensitive_data.server_key->rsa->n),
1930 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1932 /* Read clients reply (cipher type and session key). */
1933 packet_read_expect(SSH_CMSG_SESSION_KEY);
1935 /* Get cipher type and check whether we accept this. */
1936 cipher_type = packet_get_char();
1938 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1939 packet_disconnect("Warning: client selects unsupported cipher.");
1941 /* Get check bytes from the packet. These must match those we
1942 sent earlier with the public key packet. */
1943 for (i = 0; i < 8; i++)
1944 if (cookie[i] != packet_get_char())
1945 packet_disconnect("IP Spoofing check bytes do not match.");
1947 debug("Encryption type: %.200s", cipher_name(cipher_type));
1949 /* Get the encrypted integer. */
1950 if ((session_key_int = BN_new()) == NULL)
1951 fatal("do_ssh1_kex: BN_new failed");
1952 packet_get_bignum(session_key_int);
1954 protocol_flags = packet_get_int();
1955 packet_set_protocol_flags(protocol_flags);
1958 /* Decrypt session_key_int using host/server keys */
1959 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1962 * Extract session key from the decrypted integer. The key is in the
1963 * least significant 256 bits of the integer; the first byte of the
1964 * key is in the highest bits.
1967 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1968 len = BN_num_bytes(session_key_int);
1969 if (len < 0 || (u_int)len > sizeof(session_key)) {
1970 error("do_connection: bad session key len from %s: "
1971 "session_key_int %d > sizeof(session_key) %lu",
1972 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1975 memset(session_key, 0, sizeof(session_key));
1976 BN_bn2bin(session_key_int,
1977 session_key + sizeof(session_key) - len);
1979 derive_ssh1_session_id(
1980 sensitive_data.ssh1_host_key->rsa->n,
1981 sensitive_data.server_key->rsa->n,
1982 cookie, session_id);
1984 * Xor the first 16 bytes of the session key with the
1987 for (i = 0; i < 16; i++)
1988 session_key[i] ^= session_id[i];
1992 int bytes = BN_num_bytes(session_key_int);
1993 u_char *buf = xmalloc(bytes);
1996 logit("do_connection: generating a fake encryption key");
1997 BN_bn2bin(session_key_int, buf);
1999 MD5_Update(&md, buf, bytes);
2000 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2001 MD5_Final(session_key, &md);
2003 MD5_Update(&md, session_key, 16);
2004 MD5_Update(&md, buf, bytes);
2005 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2006 MD5_Final(session_key + 16, &md);
2007 memset(buf, 0, bytes);
2009 for (i = 0; i < 16; i++)
2010 session_id[i] = session_key[i] ^ session_key[i + 16];
2012 /* Destroy the private and public keys. No longer. */
2013 destroy_sensitive_data();
2016 mm_ssh1_session_id(session_id);
2018 /* Destroy the decrypted integer. It is no longer needed. */
2019 BN_clear_free(session_key_int);
2021 /* Set the session key. From this on all communications will be encrypted. */
2022 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2024 /* Destroy our copy of the session key. It is no longer needed. */
2025 memset(session_key, 0, sizeof(session_key));
2027 debug("Received session key; encryption turned on.");
2029 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2030 packet_start(SSH_SMSG_SUCCESS);
2032 packet_write_wait();
2036 * SSH2 key exchange: diffie-hellman-group1-sha1
2043 if (options.ciphers != NULL) {
2044 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2045 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2047 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2048 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2049 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2050 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2052 if (options.macs != NULL) {
2053 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2054 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2056 if (options.compression == COMP_NONE) {
2057 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2058 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2059 } else if (options.compression == COMP_DELAYED) {
2060 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2061 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2064 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2066 /* start key exchange */
2067 kex = kex_setup(myproposal);
2068 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2069 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2070 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2071 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2073 kex->client_version_string=client_version_string;
2074 kex->server_version_string=server_version_string;
2075 kex->load_host_key=&get_hostkey_by_type;
2076 kex->host_key_index=&get_hostkey_index;
2080 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2082 session_id2 = kex->session_id;
2083 session_id2_len = kex->session_id_len;
2086 /* send 1st encrypted/maced/compressed message */
2087 packet_start(SSH2_MSG_IGNORE);
2088 packet_put_cstring("markus");
2090 packet_write_wait();
2095 /* server specific fatal cleanup */
2100 do_cleanup(the_authctxt);
2101 #ifdef SSH_AUDIT_EVENTS
2102 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2103 if (!use_privsep || mm_is_monitor())
2104 audit_event(SSH_CONNECTION_ABANDON);