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 1.301 2004/08/11 11:50:09 dtucker 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;
124 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
125 * Default value is AF_UNSPEC means both IPv4 and IPv6.
127 int IPv4or6 = AF_UNSPEC;
130 * Debug mode flag. This can be set on the command line. If debug
131 * mode is enabled, extra debugging output will be sent to the system
132 * log, the daemon will not go to background, and will exit after processing
133 * the first connection.
137 /* Flag indicating that the daemon should only test the configuration and keys. */
140 /* Flag indicating that the daemon is being started from inetd. */
143 /* Flag indicating that sshd should not detach and become a daemon. */
144 int no_daemon_flag = 0;
146 /* debug goes to stderr unless inetd_flag is set */
149 /* Saved arguments to main(). */
154 int rexeced_flag = 0;
160 * The sockets that the server is listening; this is used in the SIGHUP
163 #define MAX_LISTEN_SOCKS 16
164 int listen_socks[MAX_LISTEN_SOCKS];
165 int num_listen_socks = 0;
168 * the client's version string, passed by sshd2 in compat mode. if != NULL,
169 * sshd will skip the version-number exchange
171 char *client_version_string = NULL;
172 char *server_version_string = NULL;
174 /* for rekeying XXX fixme */
178 * Any really sensitive data in the application is contained in this
179 * structure. The idea is that this structure could be locked into memory so
180 * that the pages do not get written into swap. However, there are some
181 * problems. The private key contains BIGNUMs, and we do not (in principle)
182 * have access to the internals of them, and locking just the structure is
183 * not very useful. Currently, memory locking is not implemented.
186 Key *server_key; /* ephemeral server key */
187 Key *ssh1_host_key; /* ssh1 host key */
188 Key **host_keys; /* all private host keys */
191 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
195 * Flag indicating whether the RSA server key needs to be regenerated.
196 * Is set in the SIGALRM handler and cleared when the key is regenerated.
198 static volatile sig_atomic_t key_do_regen = 0;
200 /* This is set to true when a signal is received. */
201 static volatile sig_atomic_t received_sighup = 0;
202 static volatile sig_atomic_t received_sigterm = 0;
204 /* session identifier, used by RSA-auth */
205 u_char session_id[16];
208 u_char *session_id2 = NULL;
209 u_int session_id2_len = 0;
211 /* record remote hostname or ip */
212 u_int utmp_len = MAXHOSTNAMELEN;
214 /* options.max_startup sized array of fd ints */
215 int *startup_pipes = NULL;
216 int startup_pipe; /* in child */
218 /* variables used for privilege separation */
220 struct monitor *pmonitor = NULL;
222 /* global authentication context */
223 Authctxt *the_authctxt = NULL;
225 /* message to be displayed after login */
228 /* Prototypes for various functions defined later in this file. */
229 void destroy_sensitive_data(void);
230 void demote_sensitive_data(void);
232 static void do_ssh1_kex(void);
233 static void do_ssh2_kex(void);
236 * Close all listening sockets
239 close_listen_socks(void)
243 for (i = 0; i < num_listen_socks; i++)
244 close(listen_socks[i]);
245 num_listen_socks = -1;
249 close_startup_pipes(void)
254 for (i = 0; i < options.max_startups; i++)
255 if (startup_pipes[i] != -1)
256 close(startup_pipes[i]);
260 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
261 * the effect is to reread the configuration file (and to regenerate
265 sighup_handler(int sig)
267 int save_errno = errno;
270 signal(SIGHUP, sighup_handler);
275 * Called from the main program after receiving SIGHUP.
276 * Restarts the server.
281 logit("Received SIGHUP; restarting.");
282 close_listen_socks();
283 close_startup_pipes();
284 execv(saved_argv[0], saved_argv);
285 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
291 * Generic signal handler for terminating signals in the master daemon.
294 sigterm_handler(int sig)
296 received_sigterm = sig;
300 * SIGCHLD handler. This is called whenever a child dies. This will then
301 * reap any zombies left by exited children.
304 main_sigchld_handler(int sig)
306 int save_errno = errno;
310 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
311 (pid < 0 && errno == EINTR))
314 signal(SIGCHLD, main_sigchld_handler);
319 * Signal handler for the alarm after the login grace period has expired.
322 grace_alarm_handler(int sig)
324 /* XXX no idea how fix this signal handler */
326 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
327 kill(pmonitor->m_pid, SIGALRM);
329 /* Log error and exit. */
330 fatal("Timeout before authentication for %s", get_remote_ipaddr());
334 * Signal handler for the key regeneration alarm. Note that this
335 * alarm only occurs in the daemon waiting for connections, and it does not
336 * do anything with the private key or random state before forking.
337 * Thus there should be no concurrency control/asynchronous execution
341 generate_ephemeral_server_key(void)
346 verbose("Generating %s%d bit RSA key.",
347 sensitive_data.server_key ? "new " : "", options.server_key_bits);
348 if (sensitive_data.server_key != NULL)
349 key_free(sensitive_data.server_key);
350 sensitive_data.server_key = key_generate(KEY_RSA1,
351 options.server_key_bits);
352 verbose("RSA key generation complete.");
354 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
357 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
364 key_regeneration_alarm(int sig)
366 int save_errno = errno;
368 signal(SIGALRM, SIG_DFL);
374 sshd_exchange_identification(int sock_in, int sock_out)
377 int remote_major, remote_minor;
380 char buf[256]; /* Must not be larger than remote_version. */
381 char remote_version[256]; /* Must be at least as big as buf. */
383 if ((options.protocol & SSH_PROTO_1) &&
384 (options.protocol & SSH_PROTO_2)) {
385 major = PROTOCOL_MAJOR_1;
387 } else if (options.protocol & SSH_PROTO_2) {
388 major = PROTOCOL_MAJOR_2;
389 minor = PROTOCOL_MINOR_2;
391 major = PROTOCOL_MAJOR_1;
392 minor = PROTOCOL_MINOR_1;
394 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
395 server_version_string = xstrdup(buf);
397 /* Send our protocol version identification. */
398 if (atomicio(vwrite, sock_out, server_version_string,
399 strlen(server_version_string))
400 != strlen(server_version_string)) {
401 logit("Could not write ident string to %s", get_remote_ipaddr());
405 /* Read other sides version identification. */
406 memset(buf, 0, sizeof(buf));
407 for (i = 0; i < sizeof(buf) - 1; i++) {
408 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
409 logit("Did not receive identification string from %s",
410 get_remote_ipaddr());
413 if (buf[i] == '\r') {
415 /* Kludge for F-Secure Macintosh < 1.0.2 */
417 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
421 if (buf[i] == '\n') {
426 buf[sizeof(buf) - 1] = 0;
427 client_version_string = xstrdup(buf);
430 * Check that the versions match. In future this might accept
431 * several versions and set appropriate flags to handle them.
433 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
434 &remote_major, &remote_minor, remote_version) != 3) {
435 s = "Protocol mismatch.\n";
436 (void) atomicio(vwrite, sock_out, s, strlen(s));
439 logit("Bad protocol version identification '%.100s' from %s",
440 client_version_string, get_remote_ipaddr());
443 debug("Client protocol version %d.%d; client software version %.100s",
444 remote_major, remote_minor, remote_version);
446 compat_datafellows(remote_version);
448 if (datafellows & SSH_BUG_PROBE) {
449 logit("probed from %s with %s. Don't panic.",
450 get_remote_ipaddr(), client_version_string);
454 if (datafellows & SSH_BUG_SCANNER) {
455 logit("scanned from %s with %s. Don't panic.",
456 get_remote_ipaddr(), client_version_string);
461 switch (remote_major) {
463 if (remote_minor == 99) {
464 if (options.protocol & SSH_PROTO_2)
470 if (!(options.protocol & SSH_PROTO_1)) {
474 if (remote_minor < 3) {
475 packet_disconnect("Your ssh version is too old and "
476 "is no longer supported. Please install a newer version.");
477 } else if (remote_minor == 3) {
478 /* note that this disables agent-forwarding */
483 if (options.protocol & SSH_PROTO_2) {
492 chop(server_version_string);
493 debug("Local version string %.200s", server_version_string);
496 s = "Protocol major versions differ.\n";
497 (void) atomicio(vwrite, sock_out, s, strlen(s));
500 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
502 server_version_string, client_version_string);
507 /* Destroy the host and server keys. They will no longer be needed. */
509 destroy_sensitive_data(void)
513 if (sensitive_data.server_key) {
514 key_free(sensitive_data.server_key);
515 sensitive_data.server_key = NULL;
517 for (i = 0; i < options.num_host_key_files; i++) {
518 if (sensitive_data.host_keys[i]) {
519 key_free(sensitive_data.host_keys[i]);
520 sensitive_data.host_keys[i] = NULL;
523 sensitive_data.ssh1_host_key = NULL;
524 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
527 /* Demote private to public keys for network child */
529 demote_sensitive_data(void)
534 if (sensitive_data.server_key) {
535 tmp = key_demote(sensitive_data.server_key);
536 key_free(sensitive_data.server_key);
537 sensitive_data.server_key = tmp;
540 for (i = 0; i < options.num_host_key_files; i++) {
541 if (sensitive_data.host_keys[i]) {
542 tmp = key_demote(sensitive_data.host_keys[i]);
543 key_free(sensitive_data.host_keys[i]);
544 sensitive_data.host_keys[i] = tmp;
545 if (tmp->type == KEY_RSA1)
546 sensitive_data.ssh1_host_key = tmp;
550 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
554 privsep_preauth_child(void)
561 /* Enable challenge-response authentication for privilege separation */
562 privsep_challenge_enable();
564 for (i = 0; i < 256; i++)
565 rnd[i] = arc4random();
566 RAND_seed(rnd, sizeof(rnd));
568 /* Demote the private keys to public keys. */
569 demote_sensitive_data();
571 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
572 fatal("Privilege separation user %s does not exist",
574 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
577 /* Change our root directory */
578 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
579 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
581 if (chdir("/") == -1)
582 fatal("chdir(\"/\"): %s", strerror(errno));
584 /* Drop our privileges */
585 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
588 /* XXX not ready, too heavy after chroot */
589 do_setusercontext(pw);
591 gidset[0] = pw->pw_gid;
592 if (setgroups(1, gidset) < 0)
593 fatal("setgroups: %.100s", strerror(errno));
594 permanently_set_uid(pw);
599 privsep_preauth(Authctxt *authctxt)
604 /* Set up unprivileged child process to deal with network data */
605 pmonitor = monitor_init();
606 /* Store a pointer to the kex for later rekeying */
607 pmonitor->m_pkex = &xxx_kex;
611 fatal("fork of unprivileged child failed");
612 } else if (pid != 0) {
613 debug2("Network child is on pid %ld", (long)pid);
615 close(pmonitor->m_recvfd);
616 pmonitor->m_pid = pid;
617 monitor_child_preauth(authctxt, pmonitor);
618 close(pmonitor->m_sendfd);
621 monitor_sync(pmonitor);
623 /* Wait for the child's exit status */
624 while (waitpid(pid, &status, 0) < 0)
631 close(pmonitor->m_sendfd);
633 /* Demote the child */
634 if (getuid() == 0 || geteuid() == 0)
635 privsep_preauth_child();
636 setproctitle("%s", "[net]");
642 privsep_postauth(Authctxt *authctxt)
644 #ifdef DISABLE_FD_PASSING
647 if (authctxt->pw->pw_uid == 0 || options.use_login) {
649 /* File descriptor passing is broken or root login */
650 monitor_apply_keystate(pmonitor);
655 /* Authentication complete */
657 if (startup_pipe != -1) {
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);
686 /* It is safe now to apply the key state */
687 monitor_apply_keystate(pmonitor);
691 list_hostkey_types(void)
699 for (i = 0; i < options.num_host_key_files; i++) {
700 Key *key = sensitive_data.host_keys[i];
706 if (buffer_len(&b) > 0)
707 buffer_append(&b, ",", 1);
708 p = key_ssh_name(key);
709 buffer_append(&b, p, strlen(p));
713 buffer_append(&b, "\0", 1);
714 ret = xstrdup(buffer_ptr(&b));
716 debug("list_hostkey_types: %s", ret);
721 get_hostkey_by_type(int type)
725 for (i = 0; i < options.num_host_key_files; i++) {
726 Key *key = sensitive_data.host_keys[i];
727 if (key != NULL && key->type == type)
734 get_hostkey_by_index(int ind)
736 if (ind < 0 || ind >= options.num_host_key_files)
738 return (sensitive_data.host_keys[ind]);
742 get_hostkey_index(Key *key)
746 for (i = 0; i < options.num_host_key_files; i++) {
747 if (key == sensitive_data.host_keys[i])
754 * returns 1 if connection should be dropped, 0 otherwise.
755 * dropping starts at connection #max_startups_begin with a probability
756 * of (max_startups_rate/100). the probability increases linearly until
757 * all connections are dropped for startups > max_startups
760 drop_connection(int startups)
764 if (startups < options.max_startups_begin)
766 if (startups >= options.max_startups)
768 if (options.max_startups_rate == 100)
771 p = 100 - options.max_startups_rate;
772 p *= startups - options.max_startups_begin;
773 p /= (double) (options.max_startups - options.max_startups_begin);
774 p += options.max_startups_rate;
776 r = arc4random() / (double) UINT_MAX;
778 debug("drop_connection: p %g, r %g", p, r);
779 return (r < p) ? 1 : 0;
785 fprintf(stderr, "%s, %s\n",
786 SSH_VERSION, 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], config_s[2];
900 int ret, key_used = 0;
903 #ifdef HAVE_SECUREWARE
904 (void)set_auth_parameters(ac, av);
906 __progname = ssh_get_progname(av[0]);
908 config_file_name = _PATH_SERVER_CONFIG_FILE;
911 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
914 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
915 for (i = 0; i < ac; i++)
916 saved_argv[i] = xstrdup(av[i]);
917 saved_argv[i] = NULL;
919 #ifndef HAVE_SETPROCTITLE
920 /* Prepare for later setproctitle emulation */
921 compat_init_setproctitle(ac, av);
925 if (geteuid() == 0 && setgroups(0, NULL) == -1)
926 debug("setgroups(): %.200s", strerror(errno));
928 /* Initialize configuration options to their default values. */
929 initialize_server_options(&options);
931 /* Parse command-line arguments. */
932 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
941 config_file_name = optarg;
944 if (debug_flag == 0) {
946 options.log_level = SYSLOG_LEVEL_DEBUG1;
947 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
970 options.log_level = SYSLOG_LEVEL_QUIET;
973 options.server_key_bits = atoi(optarg);
976 options.ports_from_cmdline = 1;
977 if (options.num_ports >= MAX_PORTS) {
978 fprintf(stderr, "too many ports.\n");
981 options.ports[options.num_ports++] = a2port(optarg);
982 if (options.ports[options.num_ports-1] == 0) {
983 fprintf(stderr, "Bad port number.\n");
988 if ((options.login_grace_time = convtime(optarg)) == -1) {
989 fprintf(stderr, "Invalid login grace time.\n");
994 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
995 fprintf(stderr, "Invalid key regeneration interval.\n");
1000 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1001 fprintf(stderr, "too many host keys.\n");
1004 options.host_key_files[options.num_host_key_files++] = optarg;
1010 utmp_len = atoi(optarg);
1011 if (utmp_len > MAXHOSTNAMELEN) {
1012 fprintf(stderr, "Invalid utmp length.\n");
1017 line = xstrdup(optarg);
1018 if (process_server_config_line(&options, line,
1019 "command-line", 0) != 0)
1029 if (rexeced_flag || inetd_flag)
1031 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1032 fatal("sshd re-exec requires execution with an absolute path");
1034 closefrom(REEXEC_MIN_FREE_FD);
1036 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1038 SSLeay_add_all_algorithms();
1039 channel_set_af(IPv4or6);
1042 * Force logging to stderr until we have loaded the private host
1043 * key (unless started from inetd)
1045 log_init(__progname,
1046 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1047 SYSLOG_LEVEL_INFO : options.log_level,
1048 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1049 SYSLOG_FACILITY_AUTH : options.log_facility,
1050 log_stderr || !inetd_flag);
1054 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1055 * root's environment
1057 unsetenv("KRB5CCNAME");
1060 /* Cray can define user privs drop all privs now!
1061 * Not needed on PRIV_SU systems!
1068 sensitive_data.server_key = NULL;
1069 sensitive_data.ssh1_host_key = NULL;
1070 sensitive_data.have_ssh1_key = 0;
1071 sensitive_data.have_ssh2_key = 0;
1073 /* Fetch our configuration */
1076 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1078 load_server_config(config_file_name, &cfg);
1080 parse_server_config(&options,
1081 rexeced_flag ? "rexec" : config_file_name, &cfg);
1086 /* Fill in default values for those options not explicitly set. */
1087 fill_default_server_options(&options);
1089 /* Check that there are no remaining arguments. */
1091 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1095 debug("sshd version %.100s", SSH_VERSION);
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)
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 (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1291 ntop, sizeof(ntop), strport, sizeof(strport),
1292 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1293 error("getnameinfo failed");
1296 /* Create socket for listening. */
1297 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1299 if (listen_sock < 0) {
1300 /* kernel may not support ipv6 */
1301 verbose("socket: %.100s", strerror(errno));
1304 if (set_nonblock(listen_sock) == -1) {
1309 * Set socket options.
1310 * Allow local port reuse in TIME_WAIT.
1312 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1313 &on, sizeof(on)) == -1)
1314 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1316 debug("Bind to port %s on %s.", strport, ntop);
1318 /* Bind the socket to the desired port. */
1319 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1321 error("Bind to port %s on %s failed: %.200s.",
1322 strport, ntop, strerror(errno));
1326 listen_socks[num_listen_socks] = listen_sock;
1329 /* Start listening on the port. */
1330 logit("Server listening on %s port %s.", ntop, strport);
1331 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1332 fatal("listen: %.100s", strerror(errno));
1335 freeaddrinfo(options.listen_addrs);
1337 if (!num_listen_socks)
1338 fatal("Cannot bind any address.");
1340 if (options.protocol & SSH_PROTO_1)
1341 generate_ephemeral_server_key();
1344 * Arrange to restart on SIGHUP. The handler needs
1347 signal(SIGHUP, sighup_handler);
1349 signal(SIGTERM, sigterm_handler);
1350 signal(SIGQUIT, sigterm_handler);
1352 /* Arrange SIGCHLD to be caught. */
1353 signal(SIGCHLD, main_sigchld_handler);
1355 /* Write out the pid file after the sigterm handler is setup */
1358 * Record our pid in /var/run/sshd.pid to make it
1359 * easier to kill the correct sshd. We don't want to
1360 * do this before the bind above because the bind will
1361 * fail if there already is a daemon, and this will
1362 * overwrite any old pid in the file.
1364 f = fopen(options.pid_file, "wb");
1366 error("Couldn't create pid file \"%s\": %s",
1367 options.pid_file, strerror(errno));
1369 fprintf(f, "%ld\n", (long) getpid());
1374 /* setup fd set for listen */
1377 for (i = 0; i < num_listen_socks; i++)
1378 if (listen_socks[i] > maxfd)
1379 maxfd = listen_socks[i];
1380 /* pipes connected to unauthenticated childs */
1381 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1382 for (i = 0; i < options.max_startups; i++)
1383 startup_pipes[i] = -1;
1386 * Stay listening for connections until the system crashes or
1387 * the daemon is killed with a signal.
1390 if (received_sighup)
1394 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1395 fdset = (fd_set *)xmalloc(fdsetsz);
1396 memset(fdset, 0, fdsetsz);
1398 for (i = 0; i < num_listen_socks; i++)
1399 FD_SET(listen_socks[i], fdset);
1400 for (i = 0; i < options.max_startups; i++)
1401 if (startup_pipes[i] != -1)
1402 FD_SET(startup_pipes[i], fdset);
1404 /* Wait in select until there is a connection. */
1405 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1406 if (ret < 0 && errno != EINTR)
1407 error("select: %.100s", strerror(errno));
1408 if (received_sigterm) {
1409 logit("Received signal %d; terminating.",
1410 (int) received_sigterm);
1411 close_listen_socks();
1412 unlink(options.pid_file);
1415 if (key_used && key_do_regen) {
1416 generate_ephemeral_server_key();
1423 for (i = 0; i < options.max_startups; i++)
1424 if (startup_pipes[i] != -1 &&
1425 FD_ISSET(startup_pipes[i], fdset)) {
1427 * the read end of the pipe is ready
1428 * if the child has closed the pipe
1429 * after successful authentication
1430 * or if the child has died
1432 close(startup_pipes[i]);
1433 startup_pipes[i] = -1;
1436 for (i = 0; i < num_listen_socks; i++) {
1437 if (!FD_ISSET(listen_socks[i], fdset))
1439 fromlen = sizeof(from);
1440 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1443 if (errno != EINTR && errno != EWOULDBLOCK)
1444 error("accept: %.100s", strerror(errno));
1447 if (unset_nonblock(newsock) == -1) {
1451 if (drop_connection(startups) == 1) {
1452 debug("drop connection #%d", startups);
1456 if (pipe(startup_p) == -1) {
1461 if (rexec_flag && socketpair(AF_UNIX,
1462 SOCK_STREAM, 0, config_s) == -1) {
1463 error("reexec socketpair: %s",
1466 close(startup_p[0]);
1467 close(startup_p[1]);
1471 for (j = 0; j < options.max_startups; j++)
1472 if (startup_pipes[j] == -1) {
1473 startup_pipes[j] = startup_p[0];
1474 if (maxfd < startup_p[0])
1475 maxfd = startup_p[0];
1481 * Got connection. Fork a child to handle it, unless
1482 * we are in debugging mode.
1486 * In debugging mode. Close the listening
1487 * socket, and start processing the
1488 * connection without forking.
1490 debug("Server will not fork when running in debugging mode.");
1491 close_listen_socks();
1494 close(startup_p[0]);
1495 close(startup_p[1]);
1499 send_rexec_state(config_s[0],
1506 * Normal production daemon. Fork, and have
1507 * the child process the connection. The
1508 * parent continues listening.
1510 if ((pid = fork()) == 0) {
1512 * Child. Close the listening and max_startup
1513 * sockets. Start using the accepted socket.
1514 * Reinitialize logging (since our pid has
1515 * changed). We break out of the loop to handle
1518 startup_pipe = startup_p[1];
1519 close_startup_pipes();
1520 close_listen_socks();
1523 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1529 /* Parent. Stay in the loop. */
1531 error("fork: %.100s", strerror(errno));
1533 debug("Forked child %ld.", (long)pid);
1535 close(startup_p[1]);
1538 send_rexec_state(config_s[0], &cfg);
1543 /* Mark that the key has been used (it was "given" to the child). */
1544 if ((options.protocol & SSH_PROTO_1) &&
1546 /* Schedule server key regeneration alarm. */
1547 signal(SIGALRM, key_regeneration_alarm);
1548 alarm(options.key_regeneration_time);
1554 /* Close the new socket (the child is now taking care of it). */
1557 /* child process check (or debug mode) */
1558 if (num_listen_socks < 0)
1563 /* This is the child processing a new connection. */
1564 setproctitle("%s", "[accepted]");
1567 * Create a new session and process group since the 4.4BSD
1568 * setlogin() affects the entire process group. We don't
1569 * want the child to be able to affect the parent.
1571 #if !defined(SSHD_ACQUIRES_CTTY)
1573 * If setsid is called, on some platforms sshd will later acquire a
1574 * controlling terminal which will result in "could not set
1575 * controlling tty" errors.
1577 if (!debug_flag && !inetd_flag && setsid() < 0)
1578 error("setsid: %.100s", strerror(errno));
1584 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1585 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1586 dup2(newsock, STDIN_FILENO);
1587 dup2(STDIN_FILENO, STDOUT_FILENO);
1588 if (startup_pipe == -1)
1589 close(REEXEC_STARTUP_PIPE_FD);
1591 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1593 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1595 if (startup_pipe != -1)
1596 close(startup_pipe);
1598 execv(rexec_argv[0], rexec_argv);
1600 /* Reexec has failed, fall back and continue */
1601 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1602 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1603 log_init(__progname, options.log_level,
1604 options.log_facility, log_stderr);
1607 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1609 close(REEXEC_CONFIG_PASS_FD);
1610 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1611 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1612 dup2(fd, STDIN_FILENO);
1613 dup2(fd, STDOUT_FILENO);
1614 if (fd > STDERR_FILENO)
1617 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1618 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1622 * Disable the key regeneration alarm. We will not regenerate the
1623 * key since we are no longer in a position to give it to anyone. We
1624 * will not restart on SIGHUP since it no longer makes sense.
1627 signal(SIGALRM, SIG_DFL);
1628 signal(SIGHUP, SIG_DFL);
1629 signal(SIGTERM, SIG_DFL);
1630 signal(SIGQUIT, SIG_DFL);
1631 signal(SIGCHLD, SIG_DFL);
1632 signal(SIGINT, SIG_DFL);
1634 /* Set SO_KEEPALIVE if requested. */
1635 if (options.tcp_keep_alive &&
1636 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1638 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1641 * Register our connection. This turns encryption off because we do
1644 packet_set_connection(sock_in, sock_out);
1646 remote_port = get_remote_port();
1647 remote_ip = get_remote_ipaddr();
1650 /* Check whether logins are denied from this host. */
1651 if (packet_connection_is_on_socket()) {
1652 struct request_info req;
1654 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1657 if (!hosts_access(&req)) {
1658 debug("Connection refused by tcp wrapper");
1661 fatal("libwrap refuse returns");
1664 #endif /* LIBWRAP */
1666 /* Log the connection. */
1667 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1670 * We don\'t want to listen forever unless the other side
1671 * successfully authenticates itself. So we set up an alarm which is
1672 * cleared after successful authentication. A limit of zero
1673 * indicates no limit. Note that we don\'t set the alarm in debugging
1674 * mode; it is just annoying to have the server exit just when you
1675 * are about to discover the bug.
1677 signal(SIGALRM, grace_alarm_handler);
1679 alarm(options.login_grace_time);
1681 sshd_exchange_identification(sock_in, sock_out);
1682 #if defined(AFS_KRB5)
1683 /* If machine has AFS, set process authentication group. */
1688 #endif /* AFS || AFS_KRB5 */
1690 packet_set_nonblocking();
1692 /* prepare buffers to collect authentication messages */
1693 buffer_init(&loginmsg);
1695 /* allocate authentication context */
1696 authctxt = xmalloc(sizeof(*authctxt));
1697 memset(authctxt, 0, sizeof(*authctxt));
1699 /* XXX global for cleanup, access from other modules */
1700 the_authctxt = authctxt;
1703 if (privsep_preauth(authctxt) == 1)
1706 /* prepare buffer to collect messages to display to user after login */
1707 buffer_init(&loginmsg);
1709 /* perform the key exchange */
1710 /* authenticate user and start session */
1713 do_authentication2(authctxt);
1716 do_authentication(authctxt);
1719 * If we use privilege separation, the unprivileged child transfers
1720 * the current keystate and exits
1723 mm_send_keystate(pmonitor);
1729 * In privilege separation, we fork another child and prepare
1730 * file descriptor passing.
1733 privsep_postauth(authctxt);
1734 /* the monitor process [priv] will not return */
1736 destroy_sensitive_data();
1739 /* Start session. */
1740 do_authenticated(authctxt);
1742 /* The connection has been terminated. */
1743 verbose("Closing connection to %.100s", remote_ip);
1746 if (options.use_pam)
1748 #endif /* USE_PAM */
1759 * Decrypt session_key_int using our private server key and private host key
1760 * (key with larger modulus first).
1763 ssh1_session_key(BIGNUM *session_key_int)
1767 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1768 /* Server key has bigger modulus. */
1769 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1770 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1771 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1772 get_remote_ipaddr(),
1773 BN_num_bits(sensitive_data.server_key->rsa->n),
1774 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1775 SSH_KEY_BITS_RESERVED);
1777 if (rsa_private_decrypt(session_key_int, session_key_int,
1778 sensitive_data.server_key->rsa) <= 0)
1780 if (rsa_private_decrypt(session_key_int, session_key_int,
1781 sensitive_data.ssh1_host_key->rsa) <= 0)
1784 /* Host key has bigger modulus (or they are equal). */
1785 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1786 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1787 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1788 get_remote_ipaddr(),
1789 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1790 BN_num_bits(sensitive_data.server_key->rsa->n),
1791 SSH_KEY_BITS_RESERVED);
1793 if (rsa_private_decrypt(session_key_int, session_key_int,
1794 sensitive_data.ssh1_host_key->rsa) < 0)
1796 if (rsa_private_decrypt(session_key_int, session_key_int,
1797 sensitive_data.server_key->rsa) < 0)
1810 BIGNUM *session_key_int;
1811 u_char session_key[SSH_SESSION_KEY_LENGTH];
1813 u_int cipher_type, auth_mask, protocol_flags;
1817 * Generate check bytes that the client must send back in the user
1818 * packet in order for it to be accepted; this is used to defy ip
1819 * spoofing attacks. Note that this only works against somebody
1820 * doing IP spoofing from a remote machine; any machine on the local
1821 * network can still see outgoing packets and catch the random
1822 * cookie. This only affects rhosts authentication, and this is one
1823 * of the reasons why it is inherently insecure.
1825 for (i = 0; i < 8; i++) {
1828 cookie[i] = rnd & 0xff;
1833 * Send our public key. We include in the packet 64 bits of random
1834 * data that must be matched in the reply in order to prevent IP
1837 packet_start(SSH_SMSG_PUBLIC_KEY);
1838 for (i = 0; i < 8; i++)
1839 packet_put_char(cookie[i]);
1841 /* Store our public server RSA key. */
1842 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1843 packet_put_bignum(sensitive_data.server_key->rsa->e);
1844 packet_put_bignum(sensitive_data.server_key->rsa->n);
1846 /* Store our public host RSA key. */
1847 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1848 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1849 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1851 /* Put protocol flags. */
1852 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1854 /* Declare which ciphers we support. */
1855 packet_put_int(cipher_mask_ssh1(0));
1857 /* Declare supported authentication types. */
1859 if (options.rhosts_rsa_authentication)
1860 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1861 if (options.rsa_authentication)
1862 auth_mask |= 1 << SSH_AUTH_RSA;
1863 if (options.challenge_response_authentication == 1)
1864 auth_mask |= 1 << SSH_AUTH_TIS;
1865 if (options.password_authentication)
1866 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1867 packet_put_int(auth_mask);
1869 /* Send the packet and wait for it to be sent. */
1871 packet_write_wait();
1873 debug("Sent %d bit server key and %d bit host key.",
1874 BN_num_bits(sensitive_data.server_key->rsa->n),
1875 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1877 /* Read clients reply (cipher type and session key). */
1878 packet_read_expect(SSH_CMSG_SESSION_KEY);
1880 /* Get cipher type and check whether we accept this. */
1881 cipher_type = packet_get_char();
1883 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1884 packet_disconnect("Warning: client selects unsupported cipher.");
1886 /* Get check bytes from the packet. These must match those we
1887 sent earlier with the public key packet. */
1888 for (i = 0; i < 8; i++)
1889 if (cookie[i] != packet_get_char())
1890 packet_disconnect("IP Spoofing check bytes do not match.");
1892 debug("Encryption type: %.200s", cipher_name(cipher_type));
1894 /* Get the encrypted integer. */
1895 if ((session_key_int = BN_new()) == NULL)
1896 fatal("do_ssh1_kex: BN_new failed");
1897 packet_get_bignum(session_key_int);
1899 protocol_flags = packet_get_int();
1900 packet_set_protocol_flags(protocol_flags);
1903 /* Decrypt session_key_int using host/server keys */
1904 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1907 * Extract session key from the decrypted integer. The key is in the
1908 * least significant 256 bits of the integer; the first byte of the
1909 * key is in the highest bits.
1912 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1913 len = BN_num_bytes(session_key_int);
1914 if (len < 0 || len > sizeof(session_key)) {
1915 error("do_connection: bad session key len from %s: "
1916 "session_key_int %d > sizeof(session_key) %lu",
1917 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1920 memset(session_key, 0, sizeof(session_key));
1921 BN_bn2bin(session_key_int,
1922 session_key + sizeof(session_key) - len);
1924 derive_ssh1_session_id(
1925 sensitive_data.ssh1_host_key->rsa->n,
1926 sensitive_data.server_key->rsa->n,
1927 cookie, session_id);
1929 * Xor the first 16 bytes of the session key with the
1932 for (i = 0; i < 16; i++)
1933 session_key[i] ^= session_id[i];
1937 int bytes = BN_num_bytes(session_key_int);
1938 u_char *buf = xmalloc(bytes);
1941 logit("do_connection: generating a fake encryption key");
1942 BN_bn2bin(session_key_int, buf);
1944 MD5_Update(&md, buf, bytes);
1945 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1946 MD5_Final(session_key, &md);
1948 MD5_Update(&md, session_key, 16);
1949 MD5_Update(&md, buf, bytes);
1950 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1951 MD5_Final(session_key + 16, &md);
1952 memset(buf, 0, bytes);
1954 for (i = 0; i < 16; i++)
1955 session_id[i] = session_key[i] ^ session_key[i + 16];
1957 /* Destroy the private and public keys. No longer. */
1958 destroy_sensitive_data();
1961 mm_ssh1_session_id(session_id);
1963 /* Destroy the decrypted integer. It is no longer needed. */
1964 BN_clear_free(session_key_int);
1966 /* Set the session key. From this on all communications will be encrypted. */
1967 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1969 /* Destroy our copy of the session key. It is no longer needed. */
1970 memset(session_key, 0, sizeof(session_key));
1972 debug("Received session key; encryption turned on.");
1974 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1975 packet_start(SSH_SMSG_SUCCESS);
1977 packet_write_wait();
1981 * SSH2 key exchange: diffie-hellman-group1-sha1
1988 if (options.ciphers != NULL) {
1989 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1990 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1992 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1993 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1994 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1995 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1997 if (options.macs != NULL) {
1998 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1999 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2001 if (!options.compression) {
2002 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2003 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2005 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2011 char *newstr = NULL;
2012 orig = myproposal[PROPOSAL_KEX_ALGS];
2014 /* If we don't have a host key, then all of the algorithms
2015 * currently in myproposal are useless */
2016 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])==0)
2019 if (options.gss_keyex)
2020 gss = ssh_gssapi_server_mechanisms();
2025 int len = strlen(orig) + strlen(gss) +2;
2026 newstr=xmalloc(len);
2027 snprintf(newstr,len,"%s,%s",gss,orig);
2033 /* If we've got GSSAPI mechanisms, then we've also got the 'null'
2034 host key algorithm, but we're not allowed to advertise it, unless
2035 its the only host key algorithm we're supporting */
2036 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) {
2037 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]="null";
2040 myproposal[PROPOSAL_KEX_ALGS]=newstr;
2042 fatal("No supported key exchange algorithms");
2046 /* start key exchange */
2047 kex = kex_setup(myproposal);
2048 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2049 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2050 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2052 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
2055 kex->client_version_string=client_version_string;
2056 kex->server_version_string=server_version_string;
2057 kex->load_host_key=&get_hostkey_by_type;
2058 kex->host_key_index=&get_hostkey_index;
2062 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2064 session_id2 = kex->session_id;
2065 session_id2_len = kex->session_id_len;
2068 /* send 1st encrypted/maced/compressed message */
2069 packet_start(SSH2_MSG_IGNORE);
2070 packet_put_cstring("markus");
2072 packet_write_wait();
2077 /* server specific fatal cleanup */
2082 do_cleanup(the_authctxt);