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 1.318 2005/12/24 02:27:41 djm Exp $");
48 #include <openssl/dh.h>
49 #include <openssl/bn.h>
50 #include <openssl/md5.h>
51 #include <openssl/rand.h>
52 #ifdef HAVE_SECUREWARE
53 #include <sys/security.h>
60 #include <gssapi/gssapi.h>
81 #include "myproposal.h"
83 #include "pathnames.h"
92 #include "monitor_mm.h"
94 #include "monitor_wrap.h"
95 #include "monitor_fdpass.h"
100 int allow_severity = LOG_INFO;
101 int deny_severity = LOG_WARNING;
109 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
110 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
111 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
112 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
114 extern char *__progname;
116 /* Server configuration options. */
117 ServerOptions options;
119 /* Name of the server configuration file. */
120 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
123 * Debug mode flag. This can be set on the command line. If debug
124 * mode is enabled, extra debugging output will be sent to the system
125 * log, the daemon will not go to background, and will exit after processing
126 * the first connection.
130 /* Flag indicating that the daemon should only test the configuration and keys. */
133 /* Flag indicating that the daemon is being started from inetd. */
136 /* Flag indicating that sshd should not detach and become a daemon. */
137 int no_daemon_flag = 0;
139 /* debug goes to stderr unless inetd_flag is set */
142 /* Saved arguments to main(). */
147 int rexeced_flag = 0;
153 * The sockets that the server is listening; this is used in the SIGHUP
156 #define MAX_LISTEN_SOCKS 16
157 int listen_socks[MAX_LISTEN_SOCKS];
158 int num_listen_socks = 0;
161 * the client's version string, passed by sshd2 in compat mode. if != NULL,
162 * sshd will skip the version-number exchange
164 char *client_version_string = NULL;
165 char *server_version_string = NULL;
167 /* for rekeying XXX fixme */
171 * Any really sensitive data in the application is contained in this
172 * structure. The idea is that this structure could be locked into memory so
173 * that the pages do not get written into swap. However, there are some
174 * problems. The private key contains BIGNUMs, and we do not (in principle)
175 * have access to the internals of them, and locking just the structure is
176 * not very useful. Currently, memory locking is not implemented.
179 Key *server_key; /* ephemeral server key */
180 Key *ssh1_host_key; /* ssh1 host key */
181 Key **host_keys; /* all private host keys */
184 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
188 * Flag indicating whether the RSA server key needs to be regenerated.
189 * Is set in the SIGALRM handler and cleared when the key is regenerated.
191 static volatile sig_atomic_t key_do_regen = 0;
193 /* This is set to true when a signal is received. */
194 static volatile sig_atomic_t received_sighup = 0;
195 static volatile sig_atomic_t received_sigterm = 0;
197 /* session identifier, used by RSA-auth */
198 u_char session_id[16];
201 u_char *session_id2 = NULL;
202 u_int session_id2_len = 0;
204 /* record remote hostname or ip */
205 u_int utmp_len = MAXHOSTNAMELEN;
207 /* options.max_startup sized array of fd ints */
208 int *startup_pipes = NULL;
209 int startup_pipe; /* in child */
211 /* variables used for privilege separation */
213 struct monitor *pmonitor = NULL;
215 /* global authentication context */
216 Authctxt *the_authctxt = NULL;
218 /* message to be displayed after login */
221 /* Prototypes for various functions defined later in this file. */
222 void destroy_sensitive_data(void);
223 void demote_sensitive_data(void);
225 static void do_ssh1_kex(void);
226 static void do_ssh2_kex(void);
229 * Close all listening sockets
232 close_listen_socks(void)
236 for (i = 0; i < num_listen_socks; i++)
237 close(listen_socks[i]);
238 num_listen_socks = -1;
242 close_startup_pipes(void)
247 for (i = 0; i < options.max_startups; i++)
248 if (startup_pipes[i] != -1)
249 close(startup_pipes[i]);
253 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
254 * the effect is to reread the configuration file (and to regenerate
258 sighup_handler(int sig)
260 int save_errno = errno;
263 signal(SIGHUP, sighup_handler);
268 * Called from the main program after receiving SIGHUP.
269 * Restarts the server.
274 logit("Received SIGHUP; restarting.");
275 close_listen_socks();
276 close_startup_pipes();
277 execv(saved_argv[0], saved_argv);
278 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
284 * Generic signal handler for terminating signals in the master daemon.
287 sigterm_handler(int sig)
289 received_sigterm = sig;
293 * SIGCHLD handler. This is called whenever a child dies. This will then
294 * reap any zombies left by exited children.
297 main_sigchld_handler(int sig)
299 int save_errno = errno;
303 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
304 (pid < 0 && errno == EINTR))
307 signal(SIGCHLD, main_sigchld_handler);
312 * Signal handler for the alarm after the login grace period has expired.
315 grace_alarm_handler(int sig)
317 /* XXX no idea how fix this signal handler */
319 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
320 kill(pmonitor->m_pid, SIGALRM);
322 /* Log error and exit. */
323 fatal("Timeout before authentication for %s", get_remote_ipaddr());
327 * Signal handler for the key regeneration alarm. Note that this
328 * alarm only occurs in the daemon waiting for connections, and it does not
329 * do anything with the private key or random state before forking.
330 * Thus there should be no concurrency control/asynchronous execution
334 generate_ephemeral_server_key(void)
339 verbose("Generating %s%d bit RSA key.",
340 sensitive_data.server_key ? "new " : "", options.server_key_bits);
341 if (sensitive_data.server_key != NULL)
342 key_free(sensitive_data.server_key);
343 sensitive_data.server_key = key_generate(KEY_RSA1,
344 options.server_key_bits);
345 verbose("RSA key generation complete.");
347 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
350 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
357 key_regeneration_alarm(int sig)
359 int save_errno = errno;
361 signal(SIGALRM, SIG_DFL);
367 sshd_exchange_identification(int sock_in, int sock_out)
371 int remote_major, remote_minor;
374 char buf[256]; /* Must not be larger than remote_version. */
375 char remote_version[256]; /* Must be at least as big as buf. */
377 if ((options.protocol & SSH_PROTO_1) &&
378 (options.protocol & SSH_PROTO_2)) {
379 major = PROTOCOL_MAJOR_1;
381 } else if (options.protocol & SSH_PROTO_2) {
382 major = PROTOCOL_MAJOR_2;
383 minor = PROTOCOL_MINOR_2;
385 major = PROTOCOL_MAJOR_1;
386 minor = PROTOCOL_MINOR_1;
388 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
389 server_version_string = xstrdup(buf);
391 /* Send our protocol version identification. */
392 if (atomicio(vwrite, sock_out, server_version_string,
393 strlen(server_version_string))
394 != strlen(server_version_string)) {
395 logit("Could not write ident string to %s", get_remote_ipaddr());
399 /* Read other sides version identification. */
400 memset(buf, 0, sizeof(buf));
401 for (i = 0; i < sizeof(buf) - 1; i++) {
402 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
403 logit("Did not receive identification string from %s",
404 get_remote_ipaddr());
407 if (buf[i] == '\r') {
409 /* Kludge for F-Secure Macintosh < 1.0.2 */
411 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
415 if (buf[i] == '\n') {
420 buf[sizeof(buf) - 1] = 0;
421 client_version_string = xstrdup(buf);
424 * Check that the versions match. In future this might accept
425 * several versions and set appropriate flags to handle them.
427 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
428 &remote_major, &remote_minor, remote_version) != 3) {
429 s = "Protocol mismatch.\n";
430 (void) atomicio(vwrite, sock_out, s, strlen(s));
433 logit("Bad protocol version identification '%.100s' from %s",
434 client_version_string, get_remote_ipaddr());
437 debug("Client protocol version %d.%d; client software version %.100s",
438 remote_major, remote_minor, remote_version);
440 compat_datafellows(remote_version);
442 if (datafellows & SSH_BUG_PROBE) {
443 logit("probed from %s with %s. Don't panic.",
444 get_remote_ipaddr(), client_version_string);
448 if (datafellows & SSH_BUG_SCANNER) {
449 logit("scanned from %s with %s. Don't panic.",
450 get_remote_ipaddr(), client_version_string);
455 switch (remote_major) {
457 if (remote_minor == 99) {
458 if (options.protocol & SSH_PROTO_2)
464 if (!(options.protocol & SSH_PROTO_1)) {
468 if (remote_minor < 3) {
469 packet_disconnect("Your ssh version is too old and "
470 "is no longer supported. Please install a newer version.");
471 } else if (remote_minor == 3) {
472 /* note that this disables agent-forwarding */
477 if (options.protocol & SSH_PROTO_2) {
486 chop(server_version_string);
487 debug("Local version string %.200s", server_version_string);
490 s = "Protocol major versions differ.\n";
491 (void) atomicio(vwrite, sock_out, s, strlen(s));
494 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
496 server_version_string, client_version_string);
501 /* Destroy the host and server keys. They will no longer be needed. */
503 destroy_sensitive_data(void)
507 if (sensitive_data.server_key) {
508 key_free(sensitive_data.server_key);
509 sensitive_data.server_key = NULL;
511 for (i = 0; i < options.num_host_key_files; i++) {
512 if (sensitive_data.host_keys[i]) {
513 key_free(sensitive_data.host_keys[i]);
514 sensitive_data.host_keys[i] = NULL;
517 sensitive_data.ssh1_host_key = NULL;
518 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
521 /* Demote private to public keys for network child */
523 demote_sensitive_data(void)
528 if (sensitive_data.server_key) {
529 tmp = key_demote(sensitive_data.server_key);
530 key_free(sensitive_data.server_key);
531 sensitive_data.server_key = tmp;
534 for (i = 0; i < options.num_host_key_files; i++) {
535 if (sensitive_data.host_keys[i]) {
536 tmp = key_demote(sensitive_data.host_keys[i]);
537 key_free(sensitive_data.host_keys[i]);
538 sensitive_data.host_keys[i] = tmp;
539 if (tmp->type == KEY_RSA1)
540 sensitive_data.ssh1_host_key = tmp;
544 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
548 privsep_preauth_child(void)
555 /* Enable challenge-response authentication for privilege separation */
556 privsep_challenge_enable();
558 for (i = 0; i < 256; i++)
559 rnd[i] = arc4random();
560 RAND_seed(rnd, sizeof(rnd));
562 /* Demote the private keys to public keys. */
563 demote_sensitive_data();
565 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
566 fatal("Privilege separation user %s does not exist",
568 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
571 /* Change our root directory */
572 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
573 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
575 if (chdir("/") == -1)
576 fatal("chdir(\"/\"): %s", strerror(errno));
578 /* Drop our privileges */
579 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
582 /* XXX not ready, too heavy after chroot */
583 do_setusercontext(pw);
585 gidset[0] = pw->pw_gid;
586 if (setgroups(1, gidset) < 0)
587 fatal("setgroups: %.100s", strerror(errno));
588 permanently_set_uid(pw);
593 privsep_preauth(Authctxt *authctxt)
598 /* Set up unprivileged child process to deal with network data */
599 pmonitor = monitor_init();
600 /* Store a pointer to the kex for later rekeying */
601 pmonitor->m_pkex = &xxx_kex;
605 fatal("fork of unprivileged child failed");
606 } else if (pid != 0) {
607 debug2("Network child is on pid %ld", (long)pid);
609 close(pmonitor->m_recvfd);
610 pmonitor->m_pid = pid;
611 monitor_child_preauth(authctxt, pmonitor);
612 close(pmonitor->m_sendfd);
615 monitor_sync(pmonitor);
617 /* Wait for the child's exit status */
618 while (waitpid(pid, &status, 0) < 0)
625 close(pmonitor->m_sendfd);
627 /* Demote the child */
628 if (getuid() == 0 || geteuid() == 0)
629 privsep_preauth_child();
630 setproctitle("%s", "[net]");
636 privsep_postauth(Authctxt *authctxt)
638 #ifdef DISABLE_FD_PASSING
641 if (authctxt->pw->pw_uid == 0 || options.use_login) {
643 /* File descriptor passing is broken or root login */
648 /* New socket pair */
649 monitor_reinit(pmonitor);
651 pmonitor->m_pid = fork();
652 if (pmonitor->m_pid == -1)
653 fatal("fork of unprivileged child failed");
654 else if (pmonitor->m_pid != 0) {
655 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
656 close(pmonitor->m_recvfd);
657 buffer_clear(&loginmsg);
658 monitor_child_postauth(pmonitor);
664 close(pmonitor->m_sendfd);
666 /* Demote the private keys to public keys. */
667 demote_sensitive_data();
669 /* Drop privileges */
670 do_setusercontext(authctxt->pw);
673 /* It is safe now to apply the key state */
674 monitor_apply_keystate(pmonitor);
677 * Tell the packet layer that authentication was successful, since
678 * this information is not part of the key state.
680 packet_set_authenticated();
684 list_hostkey_types(void)
692 for (i = 0; i < options.num_host_key_files; i++) {
693 Key *key = sensitive_data.host_keys[i];
699 if (buffer_len(&b) > 0)
700 buffer_append(&b, ",", 1);
701 p = key_ssh_name(key);
702 buffer_append(&b, p, strlen(p));
706 buffer_append(&b, "\0", 1);
707 ret = xstrdup(buffer_ptr(&b));
709 debug("list_hostkey_types: %s", ret);
714 get_hostkey_by_type(int type)
718 for (i = 0; i < options.num_host_key_files; i++) {
719 Key *key = sensitive_data.host_keys[i];
720 if (key != NULL && key->type == type)
727 get_hostkey_by_index(int ind)
729 if (ind < 0 || ind >= options.num_host_key_files)
731 return (sensitive_data.host_keys[ind]);
735 get_hostkey_index(Key *key)
739 for (i = 0; i < options.num_host_key_files; i++) {
740 if (key == sensitive_data.host_keys[i])
747 * returns 1 if connection should be dropped, 0 otherwise.
748 * dropping starts at connection #max_startups_begin with a probability
749 * of (max_startups_rate/100). the probability increases linearly until
750 * all connections are dropped for startups > max_startups
753 drop_connection(int startups)
757 if (startups < options.max_startups_begin)
759 if (startups >= options.max_startups)
761 if (options.max_startups_rate == 100)
764 p = 100 - options.max_startups_rate;
765 p *= startups - options.max_startups_begin;
766 p /= options.max_startups - options.max_startups_begin;
767 p += options.max_startups_rate;
768 r = arc4random() % 100;
770 debug("drop_connection: p %d, r %d", p, r);
771 return (r < p) ? 1 : 0;
777 fprintf(stderr, "%s, %s\n",
778 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
780 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
781 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
787 send_rexec_state(int fd, Buffer *conf)
791 debug3("%s: entering fd = %d config len %d", __func__, fd,
795 * Protocol from reexec master to child:
796 * string configuration
797 * u_int ephemeral_key_follows
798 * bignum e (only if ephemeral_key_follows == 1)
804 * string rngseed (only if OpenSSL is not self-seeded)
807 buffer_put_cstring(&m, buffer_ptr(conf));
809 if (sensitive_data.server_key != NULL &&
810 sensitive_data.server_key->type == KEY_RSA1) {
811 buffer_put_int(&m, 1);
812 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
813 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
814 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
815 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
816 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
817 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
819 buffer_put_int(&m, 0);
821 #ifndef OPENSSL_PRNG_ONLY
822 rexec_send_rng_seed(&m);
825 if (ssh_msg_send(fd, 0, &m) == -1)
826 fatal("%s: ssh_msg_send failed", __func__);
830 debug3("%s: done", __func__);
834 recv_rexec_state(int fd, Buffer *conf)
840 debug3("%s: entering fd = %d", __func__, fd);
844 if (ssh_msg_recv(fd, &m) == -1)
845 fatal("%s: ssh_msg_recv failed", __func__);
846 if (buffer_get_char(&m) != 0)
847 fatal("%s: rexec version mismatch", __func__);
849 cp = buffer_get_string(&m, &len);
851 buffer_append(conf, cp, len + 1);
854 if (buffer_get_int(&m)) {
855 if (sensitive_data.server_key != NULL)
856 key_free(sensitive_data.server_key);
857 sensitive_data.server_key = key_new_private(KEY_RSA1);
858 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
859 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
860 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
861 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
862 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
863 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
864 rsa_generate_additional_parameters(
865 sensitive_data.server_key->rsa);
868 #ifndef OPENSSL_PRNG_ONLY
869 rexec_recv_rng_seed(&m);
874 debug3("%s: done", __func__);
878 * Main program for the daemon.
881 main(int ac, char **av)
885 int opt, j, i, fdsetsz, on = 1;
886 int sock_in = -1, sock_out = -1, newsock = -1;
890 struct sockaddr_storage from;
891 const char *remote_ip;
895 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
897 int listen_sock, maxfd;
898 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
902 int ret, key_used = 0;
905 #ifdef HAVE_SECUREWARE
906 (void)set_auth_parameters(ac, av);
908 __progname = ssh_get_progname(av[0]);
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 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
931 /* Initialize configuration options to their default values. */
932 initialize_server_options(&options);
934 /* Parse command-line arguments. */
935 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
938 options.address_family = AF_INET;
941 options.address_family = AF_INET6;
944 config_file_name = optarg;
947 if (debug_flag == 0) {
949 options.log_level = SYSLOG_LEVEL_DEBUG1;
950 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
973 options.log_level = SYSLOG_LEVEL_QUIET;
976 options.server_key_bits = atoi(optarg);
979 options.ports_from_cmdline = 1;
980 if (options.num_ports >= MAX_PORTS) {
981 fprintf(stderr, "too many ports.\n");
984 options.ports[options.num_ports++] = a2port(optarg);
985 if (options.ports[options.num_ports-1] == 0) {
986 fprintf(stderr, "Bad port number.\n");
991 if ((options.login_grace_time = convtime(optarg)) == -1) {
992 fprintf(stderr, "Invalid login grace time.\n");
997 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
998 fprintf(stderr, "Invalid key regeneration interval.\n");
1003 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1004 fprintf(stderr, "too many host keys.\n");
1007 options.host_key_files[options.num_host_key_files++] = optarg;
1013 utmp_len = atoi(optarg);
1014 if (utmp_len > MAXHOSTNAMELEN) {
1015 fprintf(stderr, "Invalid utmp length.\n");
1020 line = xstrdup(optarg);
1021 if (process_server_config_line(&options, line,
1022 "command-line", 0) != 0)
1032 if (rexeced_flag || inetd_flag)
1034 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1035 fatal("sshd re-exec requires execution with an absolute path");
1037 closefrom(REEXEC_MIN_FREE_FD);
1039 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1041 SSLeay_add_all_algorithms();
1044 * Force logging to stderr until we have loaded the private host
1045 * key (unless started from inetd)
1047 log_init(__progname,
1048 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1049 SYSLOG_LEVEL_INFO : options.log_level,
1050 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1051 SYSLOG_FACILITY_AUTH : options.log_facility,
1052 log_stderr || !inetd_flag);
1055 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1056 * root's environment
1058 if (getenv("KRB5CCNAME") != NULL)
1059 unsetenv("KRB5CCNAME");
1062 /* Cray can define user privs drop all privs now!
1063 * 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);
1088 /* Fill in default values for those options not explicitly set. */
1089 fill_default_server_options(&options);
1091 /* set default channel AF */
1092 channel_set_af(options.address_family);
1094 /* Check that there are no remaining arguments. */
1096 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1100 debug("sshd version %.100s", SSH_RELEASE);
1102 /* load private host keys */
1103 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1105 for (i = 0; i < options.num_host_key_files; i++)
1106 sensitive_data.host_keys[i] = NULL;
1108 for (i = 0; i < options.num_host_key_files; i++) {
1109 key = key_load_private(options.host_key_files[i], "", NULL);
1110 sensitive_data.host_keys[i] = key;
1112 error("Could not load host key: %s",
1113 options.host_key_files[i]);
1114 sensitive_data.host_keys[i] = NULL;
1117 switch (key->type) {
1119 sensitive_data.ssh1_host_key = key;
1120 sensitive_data.have_ssh1_key = 1;
1124 sensitive_data.have_ssh2_key = 1;
1127 debug("private host key: #%d type %d %s", i, key->type,
1130 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1131 logit("Disabling protocol version 1. Could not load host key");
1132 options.protocol &= ~SSH_PROTO_1;
1134 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1135 logit("Disabling protocol version 2. Could not load host key");
1136 options.protocol &= ~SSH_PROTO_2;
1138 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1139 logit("sshd: no hostkeys available -- exiting.");
1143 /* Check certain values for sanity. */
1144 if (options.protocol & SSH_PROTO_1) {
1145 if (options.server_key_bits < 512 ||
1146 options.server_key_bits > 32768) {
1147 fprintf(stderr, "Bad server key size.\n");
1151 * Check that server and host key lengths differ sufficiently. This
1152 * is necessary to make double encryption work with rsaref. Oh, I
1153 * hate software patents. I dont know if this can go? Niels
1155 if (options.server_key_bits >
1156 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1157 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1158 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1159 SSH_KEY_BITS_RESERVED) {
1160 options.server_key_bits =
1161 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1162 SSH_KEY_BITS_RESERVED;
1163 debug("Forcing server key to %d bits to make it differ from host key.",
1164 options.server_key_bits);
1172 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1173 fatal("Privilege separation user %s does not exist",
1175 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1176 (S_ISDIR(st.st_mode) == 0))
1177 fatal("Missing privilege separation directory: %s",
1178 _PATH_PRIVSEP_CHROOT_DIR);
1181 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1182 (st.st_uid != getuid () ||
1183 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1185 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1187 fatal("%s must be owned by root and not group or "
1188 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1191 /* Configuration looks good, so exit if in test mode. */
1196 * Clear out any supplemental groups we may have inherited. This
1197 * prevents inadvertent creation of files with bad modes (in the
1198 * portable version at least, it's certainly possible for PAM
1199 * to create a file, and we can't control the code in every
1200 * module which might be used).
1202 if (setgroups(0, NULL) < 0)
1203 debug("setgroups() failed: %.200s", strerror(errno));
1206 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1207 for (i = 0; i < rexec_argc; i++) {
1208 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1209 rexec_argv[i] = saved_argv[i];
1211 rexec_argv[rexec_argc] = "-R";
1212 rexec_argv[rexec_argc + 1] = NULL;
1215 /* Initialize the log (it is reinitialized below in case we forked). */
1216 if (debug_flag && (!inetd_flag || rexeced_flag))
1218 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1221 * If not in debugging mode, and not started from inetd, disconnect
1222 * from the controlling terminal, and fork. The original process
1225 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1228 #endif /* TIOCNOTTY */
1229 if (daemon(0, 0) < 0)
1230 fatal("daemon() failed: %.200s", strerror(errno));
1232 /* Disconnect from the controlling tty. */
1234 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1236 (void) ioctl(fd, TIOCNOTTY, NULL);
1239 #endif /* TIOCNOTTY */
1241 /* Reinitialize the log (because of the fork above). */
1242 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1244 /* Initialize the random number generator. */
1247 /* Chdir to the root directory so that the current disk can be
1248 unmounted if desired. */
1251 /* ignore SIGPIPE */
1252 signal(SIGPIPE, SIG_IGN);
1254 /* Start listening for a socket, unless started from inetd. */
1260 close(REEXEC_CONFIG_PASS_FD);
1261 sock_in = sock_out = dup(STDIN_FILENO);
1263 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1264 close(REEXEC_STARTUP_PIPE_FD);
1267 sock_in = dup(STDIN_FILENO);
1268 sock_out = dup(STDOUT_FILENO);
1271 * We intentionally do not close the descriptors 0, 1, and 2
1272 * as our code for setting the descriptors won't work if
1273 * ttyfd happens to be one of those.
1275 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1276 dup2(fd, STDIN_FILENO);
1277 dup2(fd, STDOUT_FILENO);
1278 if (fd > STDOUT_FILENO)
1281 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1282 if ((options.protocol & SSH_PROTO_1) &&
1283 sensitive_data.server_key == NULL)
1284 generate_ephemeral_server_key();
1286 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1287 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1289 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1290 fatal("Too many listen sockets. "
1291 "Enlarge MAX_LISTEN_SOCKS");
1292 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1293 ntop, sizeof(ntop), strport, sizeof(strport),
1294 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1295 error("getnameinfo failed: %.100s",
1296 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1300 /* Create socket for listening. */
1301 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1303 if (listen_sock < 0) {
1304 /* kernel may not support ipv6 */
1305 verbose("socket: %.100s", strerror(errno));
1308 if (set_nonblock(listen_sock) == -1) {
1313 * Set socket options.
1314 * Allow local port reuse in TIME_WAIT.
1316 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1317 &on, sizeof(on)) == -1)
1318 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1320 debug("Bind to port %s on %s.", strport, ntop);
1322 /* Bind the socket to the desired port. */
1323 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1325 error("Bind to port %s on %s failed: %.200s.",
1326 strport, ntop, strerror(errno));
1330 listen_socks[num_listen_socks] = listen_sock;
1333 /* Start listening on the port. */
1334 logit("Server listening on %s port %s.", ntop, strport);
1335 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1336 fatal("listen: %.100s", strerror(errno));
1339 freeaddrinfo(options.listen_addrs);
1341 if (!num_listen_socks)
1342 fatal("Cannot bind any address.");
1344 if (options.protocol & SSH_PROTO_1)
1345 generate_ephemeral_server_key();
1348 * Arrange to restart on SIGHUP. The handler needs
1351 signal(SIGHUP, sighup_handler);
1353 signal(SIGTERM, sigterm_handler);
1354 signal(SIGQUIT, sigterm_handler);
1356 /* Arrange SIGCHLD to be caught. */
1357 signal(SIGCHLD, main_sigchld_handler);
1359 /* Write out the pid file after the sigterm handler is setup */
1362 * Record our pid in /var/run/sshd.pid to make it
1363 * easier to kill the correct sshd. We don't want to
1364 * do this before the bind above because the bind will
1365 * fail if there already is a daemon, and this will
1366 * overwrite any old pid in the file.
1368 f = fopen(options.pid_file, "wb");
1370 error("Couldn't create pid file \"%s\": %s",
1371 options.pid_file, strerror(errno));
1373 fprintf(f, "%ld\n", (long) getpid());
1378 /* setup fd set for listen */
1381 for (i = 0; i < num_listen_socks; i++)
1382 if (listen_socks[i] > maxfd)
1383 maxfd = listen_socks[i];
1384 /* pipes connected to unauthenticated childs */
1385 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1386 for (i = 0; i < options.max_startups; i++)
1387 startup_pipes[i] = -1;
1390 * Stay listening for connections until the system crashes or
1391 * the daemon is killed with a signal.
1394 if (received_sighup)
1398 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1399 fdset = (fd_set *)xmalloc(fdsetsz);
1400 memset(fdset, 0, fdsetsz);
1402 for (i = 0; i < num_listen_socks; i++)
1403 FD_SET(listen_socks[i], fdset);
1404 for (i = 0; i < options.max_startups; i++)
1405 if (startup_pipes[i] != -1)
1406 FD_SET(startup_pipes[i], fdset);
1408 /* Wait in select until there is a connection. */
1409 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1410 if (ret < 0 && errno != EINTR)
1411 error("select: %.100s", strerror(errno));
1412 if (received_sigterm) {
1413 logit("Received signal %d; terminating.",
1414 (int) received_sigterm);
1415 close_listen_socks();
1416 unlink(options.pid_file);
1419 if (key_used && key_do_regen) {
1420 generate_ephemeral_server_key();
1427 for (i = 0; i < options.max_startups; i++)
1428 if (startup_pipes[i] != -1 &&
1429 FD_ISSET(startup_pipes[i], fdset)) {
1431 * the read end of the pipe is ready
1432 * if the child has closed the pipe
1433 * after successful authentication
1434 * or if the child has died
1436 close(startup_pipes[i]);
1437 startup_pipes[i] = -1;
1440 for (i = 0; i < num_listen_socks; i++) {
1441 if (!FD_ISSET(listen_socks[i], fdset))
1443 fromlen = sizeof(from);
1444 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1447 if (errno != EINTR && errno != EWOULDBLOCK)
1448 error("accept: %.100s", strerror(errno));
1451 if (unset_nonblock(newsock) == -1) {
1455 if (drop_connection(startups) == 1) {
1456 debug("drop connection #%d", startups);
1460 if (pipe(startup_p) == -1) {
1465 if (rexec_flag && socketpair(AF_UNIX,
1466 SOCK_STREAM, 0, config_s) == -1) {
1467 error("reexec socketpair: %s",
1470 close(startup_p[0]);
1471 close(startup_p[1]);
1475 for (j = 0; j < options.max_startups; j++)
1476 if (startup_pipes[j] == -1) {
1477 startup_pipes[j] = startup_p[0];
1478 if (maxfd < startup_p[0])
1479 maxfd = startup_p[0];
1485 * Got connection. Fork a child to handle it, unless
1486 * we are in debugging mode.
1490 * In debugging mode. Close the listening
1491 * socket, and start processing the
1492 * connection without forking.
1494 debug("Server will not fork when running in debugging mode.");
1495 close_listen_socks();
1498 close(startup_p[0]);
1499 close(startup_p[1]);
1503 send_rexec_state(config_s[0],
1510 * Normal production daemon. Fork, and have
1511 * the child process the connection. The
1512 * parent continues listening.
1514 if ((pid = fork()) == 0) {
1516 * Child. Close the listening and max_startup
1517 * sockets. Start using the accepted socket.
1518 * Reinitialize logging (since our pid has
1519 * changed). We break out of the loop to handle
1522 startup_pipe = startup_p[1];
1523 close_startup_pipes();
1524 close_listen_socks();
1527 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1534 /* Parent. Stay in the loop. */
1536 error("fork: %.100s", strerror(errno));
1538 debug("Forked child %ld.", (long)pid);
1540 close(startup_p[1]);
1543 send_rexec_state(config_s[0], &cfg);
1548 /* Mark that the key has been used (it was "given" to the child). */
1549 if ((options.protocol & SSH_PROTO_1) &&
1551 /* Schedule server key regeneration alarm. */
1552 signal(SIGALRM, key_regeneration_alarm);
1553 alarm(options.key_regeneration_time);
1559 /* Close the new socket (the child is now taking care of it). */
1562 /* child process check (or debug mode) */
1563 if (num_listen_socks < 0)
1568 /* This is the child processing a new connection. */
1569 setproctitle("%s", "[accepted]");
1572 * Create a new session and process group since the 4.4BSD
1573 * setlogin() affects the entire process group. We don't
1574 * want the child to be able to affect the parent.
1576 #if !defined(SSHD_ACQUIRES_CTTY)
1578 * If setsid is called, on some platforms sshd will later acquire a
1579 * controlling terminal which will result in "could not set
1580 * controlling tty" errors.
1582 if (!debug_flag && !inetd_flag && setsid() < 0)
1583 error("setsid: %.100s", strerror(errno));
1589 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1590 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1591 dup2(newsock, STDIN_FILENO);
1592 dup2(STDIN_FILENO, STDOUT_FILENO);
1593 if (startup_pipe == -1)
1594 close(REEXEC_STARTUP_PIPE_FD);
1596 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1598 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1600 if (startup_pipe != -1)
1601 close(startup_pipe);
1603 execv(rexec_argv[0], rexec_argv);
1605 /* Reexec has failed, fall back and continue */
1606 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1607 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1608 log_init(__progname, options.log_level,
1609 options.log_facility, log_stderr);
1612 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1614 close(REEXEC_CONFIG_PASS_FD);
1615 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1616 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1617 dup2(fd, STDIN_FILENO);
1618 dup2(fd, STDOUT_FILENO);
1619 if (fd > STDERR_FILENO)
1622 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1623 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1627 * Disable the key regeneration alarm. We will not regenerate the
1628 * key since we are no longer in a position to give it to anyone. We
1629 * will not restart on SIGHUP since it no longer makes sense.
1632 signal(SIGALRM, SIG_DFL);
1633 signal(SIGHUP, SIG_DFL);
1634 signal(SIGTERM, SIG_DFL);
1635 signal(SIGQUIT, SIG_DFL);
1636 signal(SIGCHLD, SIG_DFL);
1637 signal(SIGINT, SIG_DFL);
1641 * Initialize the resolver. This may not happen automatically
1642 * before privsep chroot().
1644 if ((_res.options & RES_INIT) == 0) {
1645 debug("res_init()");
1650 * Force GSS-API to parse its configuration and load any
1651 * mechanism plugins.
1655 OM_uint32 minor_status;
1656 gss_indicate_mechs(&minor_status, &mechs);
1657 gss_release_oid_set(&minor_status, &mechs);
1663 * Register our connection. This turns encryption off because we do
1666 packet_set_connection(sock_in, sock_out);
1667 packet_set_server();
1669 /* Set SO_KEEPALIVE if requested. */
1670 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1671 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1672 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1674 if ((remote_port = get_remote_port()) < 0) {
1675 debug("get_remote_port failed");
1680 * We use get_canonical_hostname with usedns = 0 instead of
1681 * get_remote_ipaddr here so IP options will be checked.
1683 remote_ip = get_canonical_hostname(0);
1685 #ifdef SSH_AUDIT_EVENTS
1686 audit_connection_from(remote_ip, remote_port);
1689 /* Check whether logins are denied from this host. */
1690 if (packet_connection_is_on_socket()) {
1691 struct request_info req;
1693 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1696 if (!hosts_access(&req)) {
1697 debug("Connection refused by tcp wrapper");
1700 fatal("libwrap refuse returns");
1703 #endif /* LIBWRAP */
1705 /* Log the connection. */
1706 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1709 * We don't want to listen forever unless the other side
1710 * successfully authenticates itself. So we set up an alarm which is
1711 * cleared after successful authentication. A limit of zero
1712 * indicates no limit. Note that we don't set the alarm in debugging
1713 * mode; it is just annoying to have the server exit just when you
1714 * are about to discover the bug.
1716 signal(SIGALRM, grace_alarm_handler);
1718 alarm(options.login_grace_time);
1720 sshd_exchange_identification(sock_in, sock_out);
1722 packet_set_nonblocking();
1724 /* allocate authentication context */
1725 authctxt = xmalloc(sizeof(*authctxt));
1726 memset(authctxt, 0, sizeof(*authctxt));
1728 authctxt->loginmsg = &loginmsg;
1730 /* XXX global for cleanup, access from other modules */
1731 the_authctxt = authctxt;
1733 /* prepare buffer to collect messages to display to user after login */
1734 buffer_init(&loginmsg);
1737 if (privsep_preauth(authctxt) == 1)
1740 /* perform the key exchange */
1741 /* authenticate user and start session */
1744 do_authentication2(authctxt);
1747 do_authentication(authctxt);
1750 * If we use privilege separation, the unprivileged child transfers
1751 * the current keystate and exits
1754 mm_send_keystate(pmonitor);
1760 * Cancel the alarm we set to limit the time taken for
1764 signal(SIGALRM, SIG_DFL);
1765 if (startup_pipe != -1) {
1766 close(startup_pipe);
1770 #ifdef SSH_AUDIT_EVENTS
1771 audit_event(SSH_AUTH_SUCCESS);
1775 * In privilege separation, we fork another child and prepare
1776 * file descriptor passing.
1779 privsep_postauth(authctxt);
1780 /* the monitor process [priv] will not return */
1782 destroy_sensitive_data();
1785 /* Start session. */
1786 do_authenticated(authctxt);
1788 /* The connection has been terminated. */
1789 verbose("Closing connection to %.100s", remote_ip);
1792 if (options.use_pam)
1794 #endif /* USE_PAM */
1796 #ifdef SSH_AUDIT_EVENTS
1797 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1809 * Decrypt session_key_int using our private server key and private host key
1810 * (key with larger modulus first).
1813 ssh1_session_key(BIGNUM *session_key_int)
1817 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1818 /* Server key has bigger modulus. */
1819 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1820 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1821 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1822 get_remote_ipaddr(),
1823 BN_num_bits(sensitive_data.server_key->rsa->n),
1824 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1825 SSH_KEY_BITS_RESERVED);
1827 if (rsa_private_decrypt(session_key_int, session_key_int,
1828 sensitive_data.server_key->rsa) <= 0)
1830 if (rsa_private_decrypt(session_key_int, session_key_int,
1831 sensitive_data.ssh1_host_key->rsa) <= 0)
1834 /* Host key has bigger modulus (or they are equal). */
1835 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1836 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1837 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1838 get_remote_ipaddr(),
1839 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1840 BN_num_bits(sensitive_data.server_key->rsa->n),
1841 SSH_KEY_BITS_RESERVED);
1843 if (rsa_private_decrypt(session_key_int, session_key_int,
1844 sensitive_data.ssh1_host_key->rsa) < 0)
1846 if (rsa_private_decrypt(session_key_int, session_key_int,
1847 sensitive_data.server_key->rsa) < 0)
1860 BIGNUM *session_key_int;
1861 u_char session_key[SSH_SESSION_KEY_LENGTH];
1863 u_int cipher_type, auth_mask, protocol_flags;
1867 * Generate check bytes that the client must send back in the user
1868 * packet in order for it to be accepted; this is used to defy ip
1869 * spoofing attacks. Note that this only works against somebody
1870 * doing IP spoofing from a remote machine; any machine on the local
1871 * network can still see outgoing packets and catch the random
1872 * cookie. This only affects rhosts authentication, and this is one
1873 * of the reasons why it is inherently insecure.
1875 for (i = 0; i < 8; i++) {
1878 cookie[i] = rnd & 0xff;
1883 * Send our public key. We include in the packet 64 bits of random
1884 * data that must be matched in the reply in order to prevent IP
1887 packet_start(SSH_SMSG_PUBLIC_KEY);
1888 for (i = 0; i < 8; i++)
1889 packet_put_char(cookie[i]);
1891 /* Store our public server RSA key. */
1892 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1893 packet_put_bignum(sensitive_data.server_key->rsa->e);
1894 packet_put_bignum(sensitive_data.server_key->rsa->n);
1896 /* Store our public host RSA key. */
1897 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1898 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1899 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1901 /* Put protocol flags. */
1902 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1904 /* Declare which ciphers we support. */
1905 packet_put_int(cipher_mask_ssh1(0));
1907 /* Declare supported authentication types. */
1909 if (options.rhosts_rsa_authentication)
1910 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1911 if (options.rsa_authentication)
1912 auth_mask |= 1 << SSH_AUTH_RSA;
1913 if (options.challenge_response_authentication == 1)
1914 auth_mask |= 1 << SSH_AUTH_TIS;
1915 if (options.password_authentication)
1916 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1917 packet_put_int(auth_mask);
1919 /* Send the packet and wait for it to be sent. */
1921 packet_write_wait();
1923 debug("Sent %d bit server key and %d bit host key.",
1924 BN_num_bits(sensitive_data.server_key->rsa->n),
1925 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1927 /* Read clients reply (cipher type and session key). */
1928 packet_read_expect(SSH_CMSG_SESSION_KEY);
1930 /* Get cipher type and check whether we accept this. */
1931 cipher_type = packet_get_char();
1933 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1934 packet_disconnect("Warning: client selects unsupported cipher.");
1936 /* Get check bytes from the packet. These must match those we
1937 sent earlier with the public key packet. */
1938 for (i = 0; i < 8; i++)
1939 if (cookie[i] != packet_get_char())
1940 packet_disconnect("IP Spoofing check bytes do not match.");
1942 debug("Encryption type: %.200s", cipher_name(cipher_type));
1944 /* Get the encrypted integer. */
1945 if ((session_key_int = BN_new()) == NULL)
1946 fatal("do_ssh1_kex: BN_new failed");
1947 packet_get_bignum(session_key_int);
1949 protocol_flags = packet_get_int();
1950 packet_set_protocol_flags(protocol_flags);
1953 /* Decrypt session_key_int using host/server keys */
1954 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1957 * Extract session key from the decrypted integer. The key is in the
1958 * least significant 256 bits of the integer; the first byte of the
1959 * key is in the highest bits.
1962 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1963 len = BN_num_bytes(session_key_int);
1964 if (len < 0 || (u_int)len > sizeof(session_key)) {
1965 error("do_connection: bad session key len from %s: "
1966 "session_key_int %d > sizeof(session_key) %lu",
1967 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1970 memset(session_key, 0, sizeof(session_key));
1971 BN_bn2bin(session_key_int,
1972 session_key + sizeof(session_key) - len);
1974 derive_ssh1_session_id(
1975 sensitive_data.ssh1_host_key->rsa->n,
1976 sensitive_data.server_key->rsa->n,
1977 cookie, session_id);
1979 * Xor the first 16 bytes of the session key with the
1982 for (i = 0; i < 16; i++)
1983 session_key[i] ^= session_id[i];
1987 int bytes = BN_num_bytes(session_key_int);
1988 u_char *buf = xmalloc(bytes);
1991 logit("do_connection: generating a fake encryption key");
1992 BN_bn2bin(session_key_int, buf);
1994 MD5_Update(&md, buf, bytes);
1995 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1996 MD5_Final(session_key, &md);
1998 MD5_Update(&md, session_key, 16);
1999 MD5_Update(&md, buf, bytes);
2000 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2001 MD5_Final(session_key + 16, &md);
2002 memset(buf, 0, bytes);
2004 for (i = 0; i < 16; i++)
2005 session_id[i] = session_key[i] ^ session_key[i + 16];
2007 /* Destroy the private and public keys. No longer. */
2008 destroy_sensitive_data();
2011 mm_ssh1_session_id(session_id);
2013 /* Destroy the decrypted integer. It is no longer needed. */
2014 BN_clear_free(session_key_int);
2016 /* Set the session key. From this on all communications will be encrypted. */
2017 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2019 /* Destroy our copy of the session key. It is no longer needed. */
2020 memset(session_key, 0, sizeof(session_key));
2022 debug("Received session key; encryption turned on.");
2024 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2025 packet_start(SSH_SMSG_SUCCESS);
2027 packet_write_wait();
2031 * SSH2 key exchange: diffie-hellman-group1-sha1
2038 if (options.ciphers != NULL) {
2039 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2040 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2042 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2043 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2044 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2045 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2047 if (options.macs != NULL) {
2048 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2049 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2051 if (options.compression == COMP_NONE) {
2052 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2053 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2054 } else if (options.compression == COMP_DELAYED) {
2055 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2056 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2059 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2061 /* start key exchange */
2062 kex = kex_setup(myproposal);
2063 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2064 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2065 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2067 kex->client_version_string=client_version_string;
2068 kex->server_version_string=server_version_string;
2069 kex->load_host_key=&get_hostkey_by_type;
2070 kex->host_key_index=&get_hostkey_index;
2074 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2076 session_id2 = kex->session_id;
2077 session_id2_len = kex->session_id_len;
2080 /* send 1st encrypted/maced/compressed message */
2081 packet_start(SSH2_MSG_IGNORE);
2082 packet_put_cstring("markus");
2084 packet_write_wait();
2089 /* server specific fatal cleanup */
2094 do_cleanup(the_authctxt);
2095 #ifdef SSH_AUDIT_EVENTS
2096 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2097 if (!use_privsep || mm_is_monitor())
2098 audit_event(SSH_CONNECTION_ABANDON);