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 1.312 2005/07/25 11:59:40 markus Exp $");
47 #include <openssl/dh.h>
48 #include <openssl/bn.h>
49 #include <openssl/md5.h>
50 #include <openssl/rand.h>
51 #ifdef HAVE_SECUREWARE
52 #include <sys/security.h>
73 #include "myproposal.h"
75 #include "pathnames.h"
84 #include "monitor_mm.h"
86 #include "monitor_wrap.h"
87 #include "monitor_fdpass.h"
94 #include <openssl/md5.h>
101 int allow_severity = LOG_INFO;
102 int deny_severity = LOG_WARNING;
110 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
111 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
112 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
113 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
115 extern char *__progname;
117 /* Server configuration options. */
118 ServerOptions options;
120 /* Name of the server configuration file. */
121 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
124 * Debug mode flag. This can be set on the command line. If debug
125 * mode is enabled, extra debugging output will be sent to the system
126 * log, the daemon will not go to background, and will exit after processing
127 * the first connection.
131 /* Flag indicating that the daemon should only test the configuration and keys. */
134 /* Flag indicating that the daemon is being started from inetd. */
137 /* Flag indicating that sshd should not detach and become a daemon. */
138 int no_daemon_flag = 0;
140 /* debug goes to stderr unless inetd_flag is set */
143 /* Saved arguments to main(). */
148 int rexeced_flag = 0;
154 * The sockets that the server is listening; this is used in the SIGHUP
157 #define MAX_LISTEN_SOCKS 16
158 int listen_socks[MAX_LISTEN_SOCKS];
159 int num_listen_socks = 0;
162 * the client's version string, passed by sshd2 in compat mode. if != NULL,
163 * sshd will skip the version-number exchange
165 char *client_version_string = NULL;
166 char *server_version_string = NULL;
168 /* for rekeying XXX fixme */
172 * Any really sensitive data in the application is contained in this
173 * structure. The idea is that this structure could be locked into memory so
174 * that the pages do not get written into swap. However, there are some
175 * problems. The private key contains BIGNUMs, and we do not (in principle)
176 * have access to the internals of them, and locking just the structure is
177 * not very useful. Currently, memory locking is not implemented.
180 Key *server_key; /* ephemeral server key */
181 Key *ssh1_host_key; /* ssh1 host key */
182 Key **host_keys; /* all private host keys */
185 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
189 * Flag indicating whether the RSA server key needs to be regenerated.
190 * Is set in the SIGALRM handler and cleared when the key is regenerated.
192 static volatile sig_atomic_t key_do_regen = 0;
194 /* This is set to true when a signal is received. */
195 static volatile sig_atomic_t received_sighup = 0;
196 static volatile sig_atomic_t received_sigterm = 0;
198 /* session identifier, used by RSA-auth */
199 u_char session_id[16];
202 u_char *session_id2 = NULL;
203 u_int session_id2_len = 0;
205 /* record remote hostname or ip */
206 u_int utmp_len = MAXHOSTNAMELEN;
208 /* options.max_startup sized array of fd ints */
209 int *startup_pipes = NULL;
210 int startup_pipe; /* in child */
212 /* variables used for privilege separation */
214 struct monitor *pmonitor = NULL;
216 /* global authentication context */
217 Authctxt *the_authctxt = NULL;
219 /* message to be displayed after login */
222 /* Prototypes for various functions defined later in this file. */
223 void destroy_sensitive_data(void);
224 void demote_sensitive_data(void);
226 static void do_ssh1_kex(void);
227 static void do_ssh2_kex(void);
230 * Close all listening sockets
233 close_listen_socks(void)
237 for (i = 0; i < num_listen_socks; i++)
238 close(listen_socks[i]);
239 num_listen_socks = -1;
243 close_startup_pipes(void)
248 for (i = 0; i < options.max_startups; i++)
249 if (startup_pipes[i] != -1)
250 close(startup_pipes[i]);
254 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
255 * the effect is to reread the configuration file (and to regenerate
259 sighup_handler(int sig)
261 int save_errno = errno;
264 signal(SIGHUP, sighup_handler);
269 * Called from the main program after receiving SIGHUP.
270 * Restarts the server.
275 logit("Received SIGHUP; restarting.");
276 close_listen_socks();
277 close_startup_pipes();
278 execv(saved_argv[0], saved_argv);
279 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
285 * Generic signal handler for terminating signals in the master daemon.
288 sigterm_handler(int sig)
290 received_sigterm = sig;
294 * SIGCHLD handler. This is called whenever a child dies. This will then
295 * reap any zombies left by exited children.
298 main_sigchld_handler(int sig)
300 int save_errno = errno;
304 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
305 (pid < 0 && errno == EINTR))
308 signal(SIGCHLD, main_sigchld_handler);
313 * Signal handler for the alarm after the login grace period has expired.
316 grace_alarm_handler(int sig)
318 /* XXX no idea how fix this signal handler */
320 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
321 kill(pmonitor->m_pid, SIGALRM);
323 /* Log error and exit. */
324 fatal("Timeout before authentication for %s", get_remote_ipaddr());
328 * Signal handler for the key regeneration alarm. Note that this
329 * alarm only occurs in the daemon waiting for connections, and it does not
330 * do anything with the private key or random state before forking.
331 * Thus there should be no concurrency control/asynchronous execution
335 generate_ephemeral_server_key(void)
340 verbose("Generating %s%d bit RSA key.",
341 sensitive_data.server_key ? "new " : "", options.server_key_bits);
342 if (sensitive_data.server_key != NULL)
343 key_free(sensitive_data.server_key);
344 sensitive_data.server_key = key_generate(KEY_RSA1,
345 options.server_key_bits);
346 verbose("RSA key generation complete.");
348 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
351 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
358 key_regeneration_alarm(int sig)
360 int save_errno = errno;
362 signal(SIGALRM, SIG_DFL);
368 sshd_exchange_identification(int sock_in, int sock_out)
372 int remote_major, remote_minor;
375 char buf[256]; /* Must not be larger than remote_version. */
376 char remote_version[256]; /* Must be at least as big as buf. */
378 if ((options.protocol & SSH_PROTO_1) &&
379 (options.protocol & SSH_PROTO_2)) {
380 major = PROTOCOL_MAJOR_1;
382 } else if (options.protocol & SSH_PROTO_2) {
383 major = PROTOCOL_MAJOR_2;
384 minor = PROTOCOL_MINOR_2;
386 major = PROTOCOL_MAJOR_1;
387 minor = PROTOCOL_MINOR_1;
389 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
390 server_version_string = xstrdup(buf);
392 /* Send our protocol version identification. */
393 if (atomicio(vwrite, sock_out, server_version_string,
394 strlen(server_version_string))
395 != strlen(server_version_string)) {
396 logit("Could not write ident string to %s", get_remote_ipaddr());
400 /* Read other sides version identification. */
401 memset(buf, 0, sizeof(buf));
402 for (i = 0; i < sizeof(buf) - 1; i++) {
403 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
404 logit("Did not receive identification string from %s",
405 get_remote_ipaddr());
408 if (buf[i] == '\r') {
410 /* Kludge for F-Secure Macintosh < 1.0.2 */
412 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
416 if (buf[i] == '\n') {
421 buf[sizeof(buf) - 1] = 0;
422 client_version_string = xstrdup(buf);
425 * Check that the versions match. In future this might accept
426 * several versions and set appropriate flags to handle them.
428 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
429 &remote_major, &remote_minor, remote_version) != 3) {
430 s = "Protocol mismatch.\n";
431 (void) atomicio(vwrite, sock_out, s, strlen(s));
434 logit("Bad protocol version identification '%.100s' from %s",
435 client_version_string, get_remote_ipaddr());
438 debug("Client protocol version %d.%d; client software version %.100s",
439 remote_major, remote_minor, remote_version);
441 compat_datafellows(remote_version);
443 if (datafellows & SSH_BUG_PROBE) {
444 logit("probed from %s with %s. Don't panic.",
445 get_remote_ipaddr(), client_version_string);
449 if (datafellows & SSH_BUG_SCANNER) {
450 logit("scanned from %s with %s. Don't panic.",
451 get_remote_ipaddr(), client_version_string);
456 switch (remote_major) {
458 if (remote_minor == 99) {
459 if (options.protocol & SSH_PROTO_2)
465 if (!(options.protocol & SSH_PROTO_1)) {
469 if (remote_minor < 3) {
470 packet_disconnect("Your ssh version is too old and "
471 "is no longer supported. Please install a newer version.");
472 } else if (remote_minor == 3) {
473 /* note that this disables agent-forwarding */
478 if (options.protocol & SSH_PROTO_2) {
487 chop(server_version_string);
488 debug("Local version string %.200s", server_version_string);
491 s = "Protocol major versions differ.\n";
492 (void) atomicio(vwrite, sock_out, s, strlen(s));
495 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
497 server_version_string, client_version_string);
502 /* Destroy the host and server keys. They will no longer be needed. */
504 destroy_sensitive_data(void)
508 if (sensitive_data.server_key) {
509 key_free(sensitive_data.server_key);
510 sensitive_data.server_key = NULL;
512 for (i = 0; i < options.num_host_key_files; i++) {
513 if (sensitive_data.host_keys[i]) {
514 key_free(sensitive_data.host_keys[i]);
515 sensitive_data.host_keys[i] = NULL;
518 sensitive_data.ssh1_host_key = NULL;
519 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
522 /* Demote private to public keys for network child */
524 demote_sensitive_data(void)
529 if (sensitive_data.server_key) {
530 tmp = key_demote(sensitive_data.server_key);
531 key_free(sensitive_data.server_key);
532 sensitive_data.server_key = tmp;
535 for (i = 0; i < options.num_host_key_files; i++) {
536 if (sensitive_data.host_keys[i]) {
537 tmp = key_demote(sensitive_data.host_keys[i]);
538 key_free(sensitive_data.host_keys[i]);
539 sensitive_data.host_keys[i] = tmp;
540 if (tmp->type == KEY_RSA1)
541 sensitive_data.ssh1_host_key = tmp;
545 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
549 privsep_preauth_child(void)
556 /* Enable challenge-response authentication for privilege separation */
557 privsep_challenge_enable();
559 for (i = 0; i < 256; i++)
560 rnd[i] = arc4random();
561 RAND_seed(rnd, sizeof(rnd));
563 /* Demote the private keys to public keys. */
564 demote_sensitive_data();
566 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
567 fatal("Privilege separation user %s does not exist",
569 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
572 /* Change our root directory */
573 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
574 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
576 if (chdir("/") == -1)
577 fatal("chdir(\"/\"): %s", strerror(errno));
579 /* Drop our privileges */
580 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
583 /* XXX not ready, too heavy after chroot */
584 do_setusercontext(pw);
586 gidset[0] = pw->pw_gid;
587 if (setgroups(1, gidset) < 0)
588 fatal("setgroups: %.100s", strerror(errno));
589 permanently_set_uid(pw);
594 privsep_preauth(Authctxt *authctxt)
599 /* Set up unprivileged child process to deal with network data */
600 pmonitor = monitor_init();
601 /* Store a pointer to the kex for later rekeying */
602 pmonitor->m_pkex = &xxx_kex;
606 fatal("fork of unprivileged child failed");
607 } else if (pid != 0) {
608 debug2("Network child is on pid %ld", (long)pid);
610 close(pmonitor->m_recvfd);
611 pmonitor->m_pid = pid;
612 monitor_child_preauth(authctxt, pmonitor);
613 close(pmonitor->m_sendfd);
616 monitor_sync(pmonitor);
618 /* Wait for the child's exit status */
619 while (waitpid(pid, &status, 0) < 0)
626 close(pmonitor->m_sendfd);
628 /* Demote the child */
629 if (getuid() == 0 || geteuid() == 0)
630 privsep_preauth_child();
631 setproctitle("%s", "[net]");
637 privsep_postauth(Authctxt *authctxt)
639 #ifdef DISABLE_FD_PASSING
642 if (authctxt->pw->pw_uid == 0 || options.use_login) {
644 /* File descriptor passing is broken or root login */
645 monitor_apply_keystate(pmonitor);
650 /* Authentication complete */
652 if (startup_pipe != -1) {
657 /* New socket pair */
658 monitor_reinit(pmonitor);
660 pmonitor->m_pid = fork();
661 if (pmonitor->m_pid == -1)
662 fatal("fork of unprivileged child failed");
663 else if (pmonitor->m_pid != 0) {
664 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
665 close(pmonitor->m_recvfd);
666 buffer_clear(&loginmsg);
667 monitor_child_postauth(pmonitor);
673 close(pmonitor->m_sendfd);
675 /* Demote the private keys to public keys. */
676 demote_sensitive_data();
678 /* Drop privileges */
679 do_setusercontext(authctxt->pw);
681 /* It is safe now to apply the key state */
682 monitor_apply_keystate(pmonitor);
685 * Tell the packet layer that authentication was successful, since
686 * this information is not part of the key state.
688 packet_set_authenticated();
692 list_hostkey_types(void)
700 for (i = 0; i < options.num_host_key_files; i++) {
701 Key *key = sensitive_data.host_keys[i];
707 if (buffer_len(&b) > 0)
708 buffer_append(&b, ",", 1);
709 p = key_ssh_name(key);
710 buffer_append(&b, p, strlen(p));
714 buffer_append(&b, "\0", 1);
715 ret = xstrdup(buffer_ptr(&b));
717 debug("list_hostkey_types: %s", ret);
722 get_hostkey_by_type(int type)
726 for (i = 0; i < options.num_host_key_files; i++) {
727 Key *key = sensitive_data.host_keys[i];
728 if (key != NULL && key->type == type)
735 get_hostkey_by_index(int ind)
737 if (ind < 0 || ind >= options.num_host_key_files)
739 return (sensitive_data.host_keys[ind]);
743 get_hostkey_index(Key *key)
747 for (i = 0; i < options.num_host_key_files; i++) {
748 if (key == sensitive_data.host_keys[i])
755 * returns 1 if connection should be dropped, 0 otherwise.
756 * dropping starts at connection #max_startups_begin with a probability
757 * of (max_startups_rate/100). the probability increases linearly until
758 * all connections are dropped for startups > max_startups
761 drop_connection(int startups)
765 if (startups < options.max_startups_begin)
767 if (startups >= options.max_startups)
769 if (options.max_startups_rate == 100)
772 p = 100 - options.max_startups_rate;
773 p *= startups - options.max_startups_begin;
774 p /= options.max_startups - options.max_startups_begin;
775 p += options.max_startups_rate;
776 r = arc4random() % 100;
778 debug("drop_connection: p %d, r %d", p, r);
779 return (r < p) ? 1 : 0;
785 fprintf(stderr, "%s, %s\n",
786 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
788 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
789 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
795 send_rexec_state(int fd, Buffer *conf)
799 debug3("%s: entering fd = %d config len %d", __func__, fd,
803 * Protocol from reexec master to child:
804 * string configuration
805 * u_int ephemeral_key_follows
806 * bignum e (only if ephemeral_key_follows == 1)
814 buffer_put_cstring(&m, buffer_ptr(conf));
816 if (sensitive_data.server_key != NULL &&
817 sensitive_data.server_key->type == KEY_RSA1) {
818 buffer_put_int(&m, 1);
819 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
820 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
821 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
822 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
823 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
824 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
826 buffer_put_int(&m, 0);
828 if (ssh_msg_send(fd, 0, &m) == -1)
829 fatal("%s: ssh_msg_send failed", __func__);
833 debug3("%s: done", __func__);
837 recv_rexec_state(int fd, Buffer *conf)
843 debug3("%s: entering fd = %d", __func__, fd);
847 if (ssh_msg_recv(fd, &m) == -1)
848 fatal("%s: ssh_msg_recv failed", __func__);
849 if (buffer_get_char(&m) != 0)
850 fatal("%s: rexec version mismatch", __func__);
852 cp = buffer_get_string(&m, &len);
854 buffer_append(conf, cp, len + 1);
857 if (buffer_get_int(&m)) {
858 if (sensitive_data.server_key != NULL)
859 key_free(sensitive_data.server_key);
860 sensitive_data.server_key = key_new_private(KEY_RSA1);
861 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
862 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
863 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
864 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
865 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
866 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
867 rsa_generate_additional_parameters(
868 sensitive_data.server_key->rsa);
872 debug3("%s: done", __func__);
876 * Main program for the daemon.
879 main(int ac, char **av)
883 int opt, j, i, fdsetsz, on = 1;
884 int sock_in = -1, sock_out = -1, newsock = -1;
888 struct sockaddr_storage from;
889 const char *remote_ip;
893 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
895 int listen_sock, maxfd;
896 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
900 int ret, key_used = 0;
903 #ifdef HAVE_SECUREWARE
904 (void)set_auth_parameters(ac, av);
906 __progname = ssh_get_progname(av[0]);
909 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
912 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
913 for (i = 0; i < ac; i++)
914 saved_argv[i] = xstrdup(av[i]);
915 saved_argv[i] = NULL;
917 #ifndef HAVE_SETPROCTITLE
918 /* Prepare for later setproctitle emulation */
919 compat_init_setproctitle(ac, av);
923 if (geteuid() == 0 && setgroups(0, NULL) == -1)
924 debug("setgroups(): %.200s", strerror(errno));
926 /* Initialize configuration options to their default values. */
927 initialize_server_options(&options);
929 /* Parse command-line arguments. */
930 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
933 options.address_family = AF_INET;
936 options.address_family = AF_INET6;
939 config_file_name = optarg;
942 if (debug_flag == 0) {
944 options.log_level = SYSLOG_LEVEL_DEBUG1;
945 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
968 options.log_level = SYSLOG_LEVEL_QUIET;
971 options.server_key_bits = atoi(optarg);
974 options.ports_from_cmdline = 1;
975 if (options.num_ports >= MAX_PORTS) {
976 fprintf(stderr, "too many ports.\n");
979 options.ports[options.num_ports++] = a2port(optarg);
980 if (options.ports[options.num_ports-1] == 0) {
981 fprintf(stderr, "Bad port number.\n");
986 if ((options.login_grace_time = convtime(optarg)) == -1) {
987 fprintf(stderr, "Invalid login grace time.\n");
992 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
993 fprintf(stderr, "Invalid key regeneration interval.\n");
998 if (options.num_host_key_files >= MAX_HOSTKEYS) {
999 fprintf(stderr, "too many host keys.\n");
1002 options.host_key_files[options.num_host_key_files++] = optarg;
1008 utmp_len = atoi(optarg);
1009 if (utmp_len > MAXHOSTNAMELEN) {
1010 fprintf(stderr, "Invalid utmp length.\n");
1015 line = xstrdup(optarg);
1016 if (process_server_config_line(&options, line,
1017 "command-line", 0) != 0)
1027 if (rexeced_flag || inetd_flag)
1029 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1030 fatal("sshd re-exec requires execution with an absolute path");
1032 closefrom(REEXEC_MIN_FREE_FD);
1034 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1036 SSLeay_add_all_algorithms();
1039 * Force logging to stderr until we have loaded the private host
1040 * key (unless started from inetd)
1042 log_init(__progname,
1043 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1044 SYSLOG_LEVEL_INFO : options.log_level,
1045 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1046 SYSLOG_FACILITY_AUTH : options.log_facility,
1047 log_stderr || !inetd_flag);
1050 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1051 * root's environment
1053 if (getenv("KRB5CCNAME") != NULL)
1054 unsetenv("KRB5CCNAME");
1057 /* Cray can define user privs drop all privs now!
1058 * Not needed on PRIV_SU systems!
1065 sensitive_data.server_key = NULL;
1066 sensitive_data.ssh1_host_key = NULL;
1067 sensitive_data.have_ssh1_key = 0;
1068 sensitive_data.have_ssh2_key = 0;
1070 /* Fetch our configuration */
1073 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1075 load_server_config(config_file_name, &cfg);
1077 parse_server_config(&options,
1078 rexeced_flag ? "rexec" : config_file_name, &cfg);
1083 /* Fill in default values for those options not explicitly set. */
1084 fill_default_server_options(&options);
1086 /* set default channel AF */
1087 channel_set_af(options.address_family);
1089 /* Check that there are no remaining arguments. */
1091 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1095 debug("sshd version %.100s", SSH_RELEASE);
1097 /* load private host keys */
1098 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1100 for (i = 0; i < options.num_host_key_files; i++)
1101 sensitive_data.host_keys[i] = NULL;
1103 for (i = 0; i < options.num_host_key_files; i++) {
1104 key = key_load_private(options.host_key_files[i], "", NULL);
1105 sensitive_data.host_keys[i] = key;
1107 error("Could not load host key: %s",
1108 options.host_key_files[i]);
1109 sensitive_data.host_keys[i] = NULL;
1112 switch (key->type) {
1114 sensitive_data.ssh1_host_key = key;
1115 sensitive_data.have_ssh1_key = 1;
1119 sensitive_data.have_ssh2_key = 1;
1122 debug("private host key: #%d type %d %s", i, key->type,
1125 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1126 logit("Disabling protocol version 1. Could not load host key");
1127 options.protocol &= ~SSH_PROTO_1;
1130 /* The GSSAPI key exchange can run without a host key */
1131 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1132 logit("Disabling protocol version 2. Could not load host key");
1133 options.protocol &= ~SSH_PROTO_2;
1136 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1137 logit("sshd: no hostkeys available -- exiting.");
1141 /* Check certain values for sanity. */
1142 if (options.protocol & SSH_PROTO_1) {
1143 if (options.server_key_bits < 512 ||
1144 options.server_key_bits > 32768) {
1145 fprintf(stderr, "Bad server key size.\n");
1149 * Check that server and host key lengths differ sufficiently. This
1150 * is necessary to make double encryption work with rsaref. Oh, I
1151 * hate software patents. I dont know if this can go? Niels
1153 if (options.server_key_bits >
1154 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1155 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1156 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1157 SSH_KEY_BITS_RESERVED) {
1158 options.server_key_bits =
1159 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1160 SSH_KEY_BITS_RESERVED;
1161 debug("Forcing server key to %d bits to make it differ from host key.",
1162 options.server_key_bits);
1170 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1171 fatal("Privilege separation user %s does not exist",
1173 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1174 (S_ISDIR(st.st_mode) == 0))
1175 fatal("Missing privilege separation directory: %s",
1176 _PATH_PRIVSEP_CHROOT_DIR);
1179 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1180 (st.st_uid != getuid () ||
1181 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1183 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1185 fatal("%s must be owned by root and not group or "
1186 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1189 /* Configuration looks good, so exit if in test mode. */
1194 * Clear out any supplemental groups we may have inherited. This
1195 * prevents inadvertent creation of files with bad modes (in the
1196 * portable version at least, it's certainly possible for PAM
1197 * to create a file, and we can't control the code in every
1198 * module which might be used).
1200 if (setgroups(0, NULL) < 0)
1201 debug("setgroups() failed: %.200s", strerror(errno));
1204 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1205 for (i = 0; i < rexec_argc; i++) {
1206 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1207 rexec_argv[i] = saved_argv[i];
1209 rexec_argv[rexec_argc] = "-R";
1210 rexec_argv[rexec_argc + 1] = NULL;
1213 /* Initialize the log (it is reinitialized below in case we forked). */
1214 if (debug_flag && (!inetd_flag || rexeced_flag))
1216 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1219 * If not in debugging mode, and not started from inetd, disconnect
1220 * from the controlling terminal, and fork. The original process
1223 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1226 #endif /* TIOCNOTTY */
1227 if (daemon(0, 0) < 0)
1228 fatal("daemon() failed: %.200s", strerror(errno));
1230 /* Disconnect from the controlling tty. */
1232 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1234 (void) ioctl(fd, TIOCNOTTY, NULL);
1237 #endif /* TIOCNOTTY */
1239 /* Reinitialize the log (because of the fork above). */
1240 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1242 /* Initialize the random number generator. */
1245 /* Chdir to the root directory so that the current disk can be
1246 unmounted if desired. */
1249 /* ignore SIGPIPE */
1250 signal(SIGPIPE, SIG_IGN);
1252 /* Start listening for a socket, unless started from inetd. */
1258 close(REEXEC_CONFIG_PASS_FD);
1259 sock_in = sock_out = dup(STDIN_FILENO);
1261 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1262 close(REEXEC_STARTUP_PIPE_FD);
1265 sock_in = dup(STDIN_FILENO);
1266 sock_out = dup(STDOUT_FILENO);
1269 * We intentionally do not close the descriptors 0, 1, and 2
1270 * as our code for setting the descriptors won't work if
1271 * ttyfd happens to be one of those.
1273 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1274 dup2(fd, STDIN_FILENO);
1275 dup2(fd, STDOUT_FILENO);
1276 if (fd > STDOUT_FILENO)
1279 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1280 if ((options.protocol & SSH_PROTO_1) &&
1281 sensitive_data.server_key == NULL)
1282 generate_ephemeral_server_key();
1284 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1285 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1287 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1288 fatal("Too many listen sockets. "
1289 "Enlarge MAX_LISTEN_SOCKS");
1290 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1291 ntop, sizeof(ntop), strport, sizeof(strport),
1292 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1293 error("getnameinfo failed: %.100s",
1294 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1298 /* Create socket for listening. */
1299 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1301 if (listen_sock < 0) {
1302 /* kernel may not support ipv6 */
1303 verbose("socket: %.100s", strerror(errno));
1306 if (set_nonblock(listen_sock) == -1) {
1311 * Set socket options.
1312 * Allow local port reuse in TIME_WAIT.
1314 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1315 &on, sizeof(on)) == -1)
1316 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1318 debug("Bind to port %s on %s.", strport, ntop);
1320 /* Bind the socket to the desired port. */
1321 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1323 error("Bind to port %s on %s failed: %.200s.",
1324 strport, ntop, strerror(errno));
1328 listen_socks[num_listen_socks] = listen_sock;
1331 /* Start listening on the port. */
1332 logit("Server listening on %s port %s.", ntop, strport);
1333 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1334 fatal("listen: %.100s", strerror(errno));
1337 freeaddrinfo(options.listen_addrs);
1339 if (!num_listen_socks)
1340 fatal("Cannot bind any address.");
1342 if (options.protocol & SSH_PROTO_1)
1343 generate_ephemeral_server_key();
1346 * Arrange to restart on SIGHUP. The handler needs
1349 signal(SIGHUP, sighup_handler);
1351 signal(SIGTERM, sigterm_handler);
1352 signal(SIGQUIT, sigterm_handler);
1354 /* Arrange SIGCHLD to be caught. */
1355 signal(SIGCHLD, main_sigchld_handler);
1357 /* Write out the pid file after the sigterm handler is setup */
1360 * Record our pid in /var/run/sshd.pid to make it
1361 * easier to kill the correct sshd. We don't want to
1362 * do this before the bind above because the bind will
1363 * fail if there already is a daemon, and this will
1364 * overwrite any old pid in the file.
1366 f = fopen(options.pid_file, "wb");
1368 error("Couldn't create pid file \"%s\": %s",
1369 options.pid_file, strerror(errno));
1371 fprintf(f, "%ld\n", (long) getpid());
1376 /* setup fd set for listen */
1379 for (i = 0; i < num_listen_socks; i++)
1380 if (listen_socks[i] > maxfd)
1381 maxfd = listen_socks[i];
1382 /* pipes connected to unauthenticated childs */
1383 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1384 for (i = 0; i < options.max_startups; i++)
1385 startup_pipes[i] = -1;
1388 * Stay listening for connections until the system crashes or
1389 * the daemon is killed with a signal.
1392 if (received_sighup)
1396 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1397 fdset = (fd_set *)xmalloc(fdsetsz);
1398 memset(fdset, 0, fdsetsz);
1400 for (i = 0; i < num_listen_socks; i++)
1401 FD_SET(listen_socks[i], fdset);
1402 for (i = 0; i < options.max_startups; i++)
1403 if (startup_pipes[i] != -1)
1404 FD_SET(startup_pipes[i], fdset);
1406 /* Wait in select until there is a connection. */
1407 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1408 if (ret < 0 && errno != EINTR)
1409 error("select: %.100s", strerror(errno));
1410 if (received_sigterm) {
1411 logit("Received signal %d; terminating.",
1412 (int) received_sigterm);
1413 close_listen_socks();
1414 unlink(options.pid_file);
1417 if (key_used && key_do_regen) {
1418 generate_ephemeral_server_key();
1425 for (i = 0; i < options.max_startups; i++)
1426 if (startup_pipes[i] != -1 &&
1427 FD_ISSET(startup_pipes[i], fdset)) {
1429 * the read end of the pipe is ready
1430 * if the child has closed the pipe
1431 * after successful authentication
1432 * or if the child has died
1434 close(startup_pipes[i]);
1435 startup_pipes[i] = -1;
1438 for (i = 0; i < num_listen_socks; i++) {
1439 if (!FD_ISSET(listen_socks[i], fdset))
1441 fromlen = sizeof(from);
1442 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1445 if (errno != EINTR && errno != EWOULDBLOCK)
1446 error("accept: %.100s", strerror(errno));
1449 if (unset_nonblock(newsock) == -1) {
1453 if (drop_connection(startups) == 1) {
1454 debug("drop connection #%d", startups);
1458 if (pipe(startup_p) == -1) {
1463 if (rexec_flag && socketpair(AF_UNIX,
1464 SOCK_STREAM, 0, config_s) == -1) {
1465 error("reexec socketpair: %s",
1468 close(startup_p[0]);
1469 close(startup_p[1]);
1473 for (j = 0; j < options.max_startups; j++)
1474 if (startup_pipes[j] == -1) {
1475 startup_pipes[j] = startup_p[0];
1476 if (maxfd < startup_p[0])
1477 maxfd = startup_p[0];
1483 * Got connection. Fork a child to handle it, unless
1484 * we are in debugging mode.
1488 * In debugging mode. Close the listening
1489 * socket, and start processing the
1490 * connection without forking.
1492 debug("Server will not fork when running in debugging mode.");
1493 close_listen_socks();
1496 close(startup_p[0]);
1497 close(startup_p[1]);
1501 send_rexec_state(config_s[0],
1508 * Normal production daemon. Fork, and have
1509 * the child process the connection. The
1510 * parent continues listening.
1512 if ((pid = fork()) == 0) {
1514 * Child. Close the listening and max_startup
1515 * sockets. Start using the accepted socket.
1516 * Reinitialize logging (since our pid has
1517 * changed). We break out of the loop to handle
1520 startup_pipe = startup_p[1];
1521 close_startup_pipes();
1522 close_listen_socks();
1525 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1532 /* Parent. Stay in the loop. */
1534 error("fork: %.100s", strerror(errno));
1536 debug("Forked child %ld.", (long)pid);
1538 close(startup_p[1]);
1541 send_rexec_state(config_s[0], &cfg);
1546 /* Mark that the key has been used (it was "given" to the child). */
1547 if ((options.protocol & SSH_PROTO_1) &&
1549 /* Schedule server key regeneration alarm. */
1550 signal(SIGALRM, key_regeneration_alarm);
1551 alarm(options.key_regeneration_time);
1557 /* Close the new socket (the child is now taking care of it). */
1560 /* child process check (or debug mode) */
1561 if (num_listen_socks < 0)
1566 /* This is the child processing a new connection. */
1567 setproctitle("%s", "[accepted]");
1570 * Create a new session and process group since the 4.4BSD
1571 * setlogin() affects the entire process group. We don't
1572 * want the child to be able to affect the parent.
1574 #if !defined(SSHD_ACQUIRES_CTTY)
1576 * If setsid is called, on some platforms sshd will later acquire a
1577 * controlling terminal which will result in "could not set
1578 * controlling tty" errors.
1580 if (!debug_flag && !inetd_flag && setsid() < 0)
1581 error("setsid: %.100s", strerror(errno));
1587 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1588 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1589 dup2(newsock, STDIN_FILENO);
1590 dup2(STDIN_FILENO, STDOUT_FILENO);
1591 if (startup_pipe == -1)
1592 close(REEXEC_STARTUP_PIPE_FD);
1594 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1596 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1598 if (startup_pipe != -1)
1599 close(startup_pipe);
1601 execv(rexec_argv[0], rexec_argv);
1603 /* Reexec has failed, fall back and continue */
1604 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1605 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1606 log_init(__progname, options.log_level,
1607 options.log_facility, log_stderr);
1610 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1612 close(REEXEC_CONFIG_PASS_FD);
1613 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1614 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1615 dup2(fd, STDIN_FILENO);
1616 dup2(fd, STDOUT_FILENO);
1617 if (fd > STDERR_FILENO)
1620 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1621 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1625 * Disable the key regeneration alarm. We will not regenerate the
1626 * key since we are no longer in a position to give it to anyone. We
1627 * will not restart on SIGHUP since it no longer makes sense.
1630 signal(SIGALRM, SIG_DFL);
1631 signal(SIGHUP, SIG_DFL);
1632 signal(SIGTERM, SIG_DFL);
1633 signal(SIGQUIT, SIG_DFL);
1634 signal(SIGCHLD, SIG_DFL);
1635 signal(SIGINT, SIG_DFL);
1638 * Register our connection. This turns encryption off because we do
1641 packet_set_connection(sock_in, sock_out);
1642 packet_set_server();
1644 /* Set SO_KEEPALIVE if requested. */
1645 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1646 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1647 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1649 if ((remote_port = get_remote_port()) < 0) {
1650 debug("get_remote_port failed");
1653 remote_ip = get_remote_ipaddr();
1655 #ifdef SSH_AUDIT_EVENTS
1656 audit_connection_from(remote_ip, remote_port);
1659 /* Check whether logins are denied from this host. */
1660 if (packet_connection_is_on_socket()) {
1661 struct request_info req;
1663 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1666 if (!hosts_access(&req)) {
1667 debug("Connection refused by tcp wrapper");
1670 fatal("libwrap refuse returns");
1673 #endif /* LIBWRAP */
1675 /* Log the connection. */
1676 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1679 * We don\'t want to listen forever unless the other side
1680 * successfully authenticates itself. So we set up an alarm which is
1681 * cleared after successful authentication. A limit of zero
1682 * indicates no limit. Note that we don\'t set the alarm in debugging
1683 * mode; it is just annoying to have the server exit just when you
1684 * are about to discover the bug.
1686 signal(SIGALRM, grace_alarm_handler);
1688 alarm(options.login_grace_time);
1690 sshd_exchange_identification(sock_in, sock_out);
1691 #if defined(AFS_KRB5)
1692 /* If machine has AFS, set process authentication group. */
1697 #endif /* AFS || AFS_KRB5 */
1699 packet_set_nonblocking();
1701 /* allocate authentication context */
1702 authctxt = xmalloc(sizeof(*authctxt));
1703 memset(authctxt, 0, sizeof(*authctxt));
1705 authctxt->loginmsg = &loginmsg;
1707 /* XXX global for cleanup, access from other modules */
1708 the_authctxt = authctxt;
1710 /* prepare buffer to collect messages to display to user after login */
1711 buffer_init(&loginmsg);
1714 if (privsep_preauth(authctxt) == 1)
1717 /* perform the key exchange */
1718 /* authenticate user and start session */
1721 do_authentication2(authctxt);
1724 do_authentication(authctxt);
1727 * If we use privilege separation, the unprivileged child transfers
1728 * the current keystate and exits
1731 mm_send_keystate(pmonitor);
1736 #ifdef SSH_AUDIT_EVENTS
1737 audit_event(SSH_AUTH_SUCCESS);
1741 * In privilege separation, we fork another child and prepare
1742 * file descriptor passing.
1745 privsep_postauth(authctxt);
1746 /* the monitor process [priv] will not return */
1748 destroy_sensitive_data();
1751 /* Start session. */
1752 do_authenticated(authctxt);
1754 /* The connection has been terminated. */
1755 verbose("Closing connection to %.100s", remote_ip);
1758 if (options.use_pam)
1760 #endif /* USE_PAM */
1762 #ifdef SSH_AUDIT_EVENTS
1763 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1775 * Decrypt session_key_int using our private server key and private host key
1776 * (key with larger modulus first).
1779 ssh1_session_key(BIGNUM *session_key_int)
1783 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1784 /* Server key has bigger modulus. */
1785 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1786 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1787 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1788 get_remote_ipaddr(),
1789 BN_num_bits(sensitive_data.server_key->rsa->n),
1790 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1791 SSH_KEY_BITS_RESERVED);
1793 if (rsa_private_decrypt(session_key_int, session_key_int,
1794 sensitive_data.server_key->rsa) <= 0)
1796 if (rsa_private_decrypt(session_key_int, session_key_int,
1797 sensitive_data.ssh1_host_key->rsa) <= 0)
1800 /* Host key has bigger modulus (or they are equal). */
1801 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1802 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1803 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1804 get_remote_ipaddr(),
1805 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1806 BN_num_bits(sensitive_data.server_key->rsa->n),
1807 SSH_KEY_BITS_RESERVED);
1809 if (rsa_private_decrypt(session_key_int, session_key_int,
1810 sensitive_data.ssh1_host_key->rsa) < 0)
1812 if (rsa_private_decrypt(session_key_int, session_key_int,
1813 sensitive_data.server_key->rsa) < 0)
1826 BIGNUM *session_key_int;
1827 u_char session_key[SSH_SESSION_KEY_LENGTH];
1829 u_int cipher_type, auth_mask, protocol_flags;
1833 * Generate check bytes that the client must send back in the user
1834 * packet in order for it to be accepted; this is used to defy ip
1835 * spoofing attacks. Note that this only works against somebody
1836 * doing IP spoofing from a remote machine; any machine on the local
1837 * network can still see outgoing packets and catch the random
1838 * cookie. This only affects rhosts authentication, and this is one
1839 * of the reasons why it is inherently insecure.
1841 for (i = 0; i < 8; i++) {
1844 cookie[i] = rnd & 0xff;
1849 * Send our public key. We include in the packet 64 bits of random
1850 * data that must be matched in the reply in order to prevent IP
1853 packet_start(SSH_SMSG_PUBLIC_KEY);
1854 for (i = 0; i < 8; i++)
1855 packet_put_char(cookie[i]);
1857 /* Store our public server RSA key. */
1858 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1859 packet_put_bignum(sensitive_data.server_key->rsa->e);
1860 packet_put_bignum(sensitive_data.server_key->rsa->n);
1862 /* Store our public host RSA key. */
1863 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1864 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1865 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1867 /* Put protocol flags. */
1868 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1870 /* Declare which ciphers we support. */
1871 packet_put_int(cipher_mask_ssh1(0));
1873 /* Declare supported authentication types. */
1875 if (options.rhosts_rsa_authentication)
1876 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1877 if (options.rsa_authentication)
1878 auth_mask |= 1 << SSH_AUTH_RSA;
1879 if (options.challenge_response_authentication == 1)
1880 auth_mask |= 1 << SSH_AUTH_TIS;
1881 if (options.password_authentication)
1882 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1883 packet_put_int(auth_mask);
1885 /* Send the packet and wait for it to be sent. */
1887 packet_write_wait();
1889 debug("Sent %d bit server key and %d bit host key.",
1890 BN_num_bits(sensitive_data.server_key->rsa->n),
1891 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1893 /* Read clients reply (cipher type and session key). */
1894 packet_read_expect(SSH_CMSG_SESSION_KEY);
1896 /* Get cipher type and check whether we accept this. */
1897 cipher_type = packet_get_char();
1899 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1900 packet_disconnect("Warning: client selects unsupported cipher.");
1902 /* Get check bytes from the packet. These must match those we
1903 sent earlier with the public key packet. */
1904 for (i = 0; i < 8; i++)
1905 if (cookie[i] != packet_get_char())
1906 packet_disconnect("IP Spoofing check bytes do not match.");
1908 debug("Encryption type: %.200s", cipher_name(cipher_type));
1910 /* Get the encrypted integer. */
1911 if ((session_key_int = BN_new()) == NULL)
1912 fatal("do_ssh1_kex: BN_new failed");
1913 packet_get_bignum(session_key_int);
1915 protocol_flags = packet_get_int();
1916 packet_set_protocol_flags(protocol_flags);
1919 /* Decrypt session_key_int using host/server keys */
1920 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1923 * Extract session key from the decrypted integer. The key is in the
1924 * least significant 256 bits of the integer; the first byte of the
1925 * key is in the highest bits.
1928 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1929 len = BN_num_bytes(session_key_int);
1930 if (len < 0 || (u_int)len > sizeof(session_key)) {
1931 error("do_connection: bad session key len from %s: "
1932 "session_key_int %d > sizeof(session_key) %lu",
1933 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1936 memset(session_key, 0, sizeof(session_key));
1937 BN_bn2bin(session_key_int,
1938 session_key + sizeof(session_key) - len);
1940 derive_ssh1_session_id(
1941 sensitive_data.ssh1_host_key->rsa->n,
1942 sensitive_data.server_key->rsa->n,
1943 cookie, session_id);
1945 * Xor the first 16 bytes of the session key with the
1948 for (i = 0; i < 16; i++)
1949 session_key[i] ^= session_id[i];
1953 int bytes = BN_num_bytes(session_key_int);
1954 u_char *buf = xmalloc(bytes);
1957 logit("do_connection: generating a fake encryption key");
1958 BN_bn2bin(session_key_int, buf);
1960 MD5_Update(&md, buf, bytes);
1961 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1962 MD5_Final(session_key, &md);
1964 MD5_Update(&md, session_key, 16);
1965 MD5_Update(&md, buf, bytes);
1966 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1967 MD5_Final(session_key + 16, &md);
1968 memset(buf, 0, bytes);
1970 for (i = 0; i < 16; i++)
1971 session_id[i] = session_key[i] ^ session_key[i + 16];
1973 /* Destroy the private and public keys. No longer. */
1974 destroy_sensitive_data();
1977 mm_ssh1_session_id(session_id);
1979 /* Destroy the decrypted integer. It is no longer needed. */
1980 BN_clear_free(session_key_int);
1982 /* Set the session key. From this on all communications will be encrypted. */
1983 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1985 /* Destroy our copy of the session key. It is no longer needed. */
1986 memset(session_key, 0, sizeof(session_key));
1988 debug("Received session key; encryption turned on.");
1990 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1991 packet_start(SSH_SMSG_SUCCESS);
1993 packet_write_wait();
1997 * SSH2 key exchange: diffie-hellman-group1-sha1
2004 if (options.ciphers != NULL) {
2005 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2006 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2008 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2009 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2010 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2011 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2013 if (options.macs != NULL) {
2014 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2015 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2017 if (options.compression == COMP_NONE) {
2018 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2019 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2020 } else if (options.compression == COMP_DELAYED) {
2021 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2022 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2025 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2031 char *newstr = NULL;
2032 orig = myproposal[PROPOSAL_KEX_ALGS];
2034 /* If we don't have a host key, then all of the algorithms
2035 * currently in myproposal are useless */
2036 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])==0)
2039 if (options.gss_keyex)
2040 gss = ssh_gssapi_server_mechanisms();
2045 int len = strlen(orig) + strlen(gss) +2;
2046 newstr=xmalloc(len);
2047 snprintf(newstr,len,"%s,%s",gss,orig);
2053 /* If we've got GSSAPI mechanisms, then we've also got the 'null'
2054 host key algorithm, but we're not allowed to advertise it, unless
2055 its the only host key algorithm we're supporting */
2056 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) {
2057 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]="null";
2060 myproposal[PROPOSAL_KEX_ALGS]=newstr;
2062 fatal("No supported key exchange algorithms");
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;
2072 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
2075 kex->client_version_string=client_version_string;
2076 kex->server_version_string=server_version_string;
2077 kex->load_host_key=&get_hostkey_by_type;
2078 kex->host_key_index=&get_hostkey_index;
2082 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2084 session_id2 = kex->session_id;
2085 session_id2_len = kex->session_id_len;
2088 /* send 1st encrypted/maced/compressed message */
2089 packet_start(SSH2_MSG_IGNORE);
2090 packet_put_cstring("markus");
2092 packet_write_wait();
2097 /* server specific fatal cleanup */
2102 do_cleanup(the_authctxt);
2103 #ifdef SSH_AUDIT_EVENTS
2104 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2105 if (!use_privsep || mm_is_monitor())
2106 audit_event(SSH_CONNECTION_ABANDON);