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 1.325 2006/03/13 08:16:00 djm Exp $");
47 #include <sys/types.h>
48 #ifdef HAVE_SYS_STAT_H
49 # include <sys/stat.h>
51 #include <sys/ioctl.h>
59 #include <openssl/dh.h>
60 #include <openssl/bn.h>
61 #include <openssl/md5.h>
62 #include <openssl/rand.h>
63 #ifdef HAVE_SECUREWARE
64 #include <sys/security.h>
85 #include "myproposal.h"
87 #include "pathnames.h"
96 #include "monitor_mm.h"
98 #include "monitor_wrap.h"
99 #include "monitor_fdpass.h"
104 int allow_severity = LOG_INFO;
105 int deny_severity = LOG_WARNING;
113 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
114 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
115 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
116 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
118 extern char *__progname;
120 /* Server configuration options. */
121 ServerOptions options;
123 /* Name of the server configuration file. */
124 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
127 * Debug mode flag. This can be set on the command line. If debug
128 * mode is enabled, extra debugging output will be sent to the system
129 * log, the daemon will not go to background, and will exit after processing
130 * the first connection.
134 /* Flag indicating that the daemon should only test the configuration and keys. */
137 /* Flag indicating that the daemon is being started from inetd. */
140 /* Flag indicating that sshd should not detach and become a daemon. */
141 int no_daemon_flag = 0;
143 /* debug goes to stderr unless inetd_flag is set */
146 /* Saved arguments to main(). */
151 int rexeced_flag = 0;
157 * The sockets that the server is listening; this is used in the SIGHUP
160 #define MAX_LISTEN_SOCKS 16
161 int listen_socks[MAX_LISTEN_SOCKS];
162 int num_listen_socks = 0;
165 * the client's version string, passed by sshd2 in compat mode. if != NULL,
166 * sshd will skip the version-number exchange
168 char *client_version_string = NULL;
169 char *server_version_string = NULL;
171 /* for rekeying XXX fixme */
175 * Any really sensitive data in the application is contained in this
176 * structure. The idea is that this structure could be locked into memory so
177 * that the pages do not get written into swap. However, there are some
178 * problems. The private key contains BIGNUMs, and we do not (in principle)
179 * have access to the internals of them, and locking just the structure is
180 * not very useful. Currently, memory locking is not implemented.
183 Key *server_key; /* ephemeral server key */
184 Key *ssh1_host_key; /* ssh1 host key */
185 Key **host_keys; /* all private host keys */
188 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
192 * Flag indicating whether the RSA server key needs to be regenerated.
193 * Is set in the SIGALRM handler and cleared when the key is regenerated.
195 static volatile sig_atomic_t key_do_regen = 0;
197 /* This is set to true when a signal is received. */
198 static volatile sig_atomic_t received_sighup = 0;
199 static volatile sig_atomic_t received_sigterm = 0;
201 /* session identifier, used by RSA-auth */
202 u_char session_id[16];
205 u_char *session_id2 = NULL;
206 u_int session_id2_len = 0;
208 /* record remote hostname or ip */
209 u_int utmp_len = MAXHOSTNAMELEN;
211 /* options.max_startup sized array of fd ints */
212 int *startup_pipes = NULL;
213 int startup_pipe; /* in child */
215 /* variables used for privilege separation */
217 struct monitor *pmonitor = NULL;
219 /* global authentication context */
220 Authctxt *the_authctxt = NULL;
222 /* message to be displayed after login */
225 /* Prototypes for various functions defined later in this file. */
226 void destroy_sensitive_data(void);
227 void demote_sensitive_data(void);
229 static void do_ssh1_kex(void);
230 static void do_ssh2_kex(void);
233 * Close all listening sockets
236 close_listen_socks(void)
240 for (i = 0; i < num_listen_socks; i++)
241 close(listen_socks[i]);
242 num_listen_socks = -1;
246 close_startup_pipes(void)
251 for (i = 0; i < options.max_startups; i++)
252 if (startup_pipes[i] != -1)
253 close(startup_pipes[i]);
257 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
258 * the effect is to reread the configuration file (and to regenerate
262 sighup_handler(int sig)
264 int save_errno = errno;
267 signal(SIGHUP, sighup_handler);
272 * Called from the main program after receiving SIGHUP.
273 * Restarts the server.
278 logit("Received SIGHUP; restarting.");
279 close_listen_socks();
280 close_startup_pipes();
281 execv(saved_argv[0], saved_argv);
282 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
288 * Generic signal handler for terminating signals in the master daemon.
291 sigterm_handler(int sig)
293 received_sigterm = sig;
297 * SIGCHLD handler. This is called whenever a child dies. This will then
298 * reap any zombies left by exited children.
301 main_sigchld_handler(int sig)
303 int save_errno = errno;
307 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
308 (pid < 0 && errno == EINTR))
311 signal(SIGCHLD, main_sigchld_handler);
316 * Signal handler for the alarm after the login grace period has expired.
319 grace_alarm_handler(int sig)
321 /* XXX no idea how fix this signal handler */
323 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
324 kill(pmonitor->m_pid, SIGALRM);
326 /* Log error and exit. */
327 fatal("Timeout before authentication for %s", get_remote_ipaddr());
331 * Signal handler for the key regeneration alarm. Note that this
332 * alarm only occurs in the daemon waiting for connections, and it does not
333 * do anything with the private key or random state before forking.
334 * Thus there should be no concurrency control/asynchronous execution
338 generate_ephemeral_server_key(void)
343 verbose("Generating %s%d bit RSA key.",
344 sensitive_data.server_key ? "new " : "", options.server_key_bits);
345 if (sensitive_data.server_key != NULL)
346 key_free(sensitive_data.server_key);
347 sensitive_data.server_key = key_generate(KEY_RSA1,
348 options.server_key_bits);
349 verbose("RSA key generation complete.");
351 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
354 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
361 key_regeneration_alarm(int sig)
363 int save_errno = errno;
365 signal(SIGALRM, SIG_DFL);
371 sshd_exchange_identification(int sock_in, int sock_out)
375 int remote_major, remote_minor;
378 char buf[256]; /* Must not be larger than remote_version. */
379 char remote_version[256]; /* Must be at least as big as buf. */
381 if ((options.protocol & SSH_PROTO_1) &&
382 (options.protocol & SSH_PROTO_2)) {
383 major = PROTOCOL_MAJOR_1;
385 } else if (options.protocol & SSH_PROTO_2) {
386 major = PROTOCOL_MAJOR_2;
387 minor = PROTOCOL_MINOR_2;
389 major = PROTOCOL_MAJOR_1;
390 minor = PROTOCOL_MINOR_1;
392 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
393 server_version_string = xstrdup(buf);
395 /* Send our protocol version identification. */
396 if (atomicio(vwrite, sock_out, server_version_string,
397 strlen(server_version_string))
398 != strlen(server_version_string)) {
399 logit("Could not write ident string to %s", get_remote_ipaddr());
403 /* Read other sides version identification. */
404 memset(buf, 0, sizeof(buf));
405 for (i = 0; i < sizeof(buf) - 1; i++) {
406 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
407 logit("Did not receive identification string from %s",
408 get_remote_ipaddr());
411 if (buf[i] == '\r') {
413 /* Kludge for F-Secure Macintosh < 1.0.2 */
415 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
419 if (buf[i] == '\n') {
424 buf[sizeof(buf) - 1] = 0;
425 client_version_string = xstrdup(buf);
428 * Check that the versions match. In future this might accept
429 * several versions and set appropriate flags to handle them.
431 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
432 &remote_major, &remote_minor, remote_version) != 3) {
433 s = "Protocol mismatch.\n";
434 (void) atomicio(vwrite, sock_out, s, strlen(s));
437 logit("Bad protocol version identification '%.100s' from %s",
438 client_version_string, get_remote_ipaddr());
441 debug("Client protocol version %d.%d; client software version %.100s",
442 remote_major, remote_minor, remote_version);
444 compat_datafellows(remote_version);
446 if (datafellows & SSH_BUG_PROBE) {
447 logit("probed from %s with %s. Don't panic.",
448 get_remote_ipaddr(), client_version_string);
452 if (datafellows & SSH_BUG_SCANNER) {
453 logit("scanned from %s with %s. Don't panic.",
454 get_remote_ipaddr(), client_version_string);
459 switch (remote_major) {
461 if (remote_minor == 99) {
462 if (options.protocol & SSH_PROTO_2)
468 if (!(options.protocol & SSH_PROTO_1)) {
472 if (remote_minor < 3) {
473 packet_disconnect("Your ssh version is too old and "
474 "is no longer supported. Please install a newer version.");
475 } else if (remote_minor == 3) {
476 /* note that this disables agent-forwarding */
481 if (options.protocol & SSH_PROTO_2) {
490 chop(server_version_string);
491 debug("Local version string %.200s", server_version_string);
494 s = "Protocol major versions differ.\n";
495 (void) atomicio(vwrite, sock_out, s, strlen(s));
498 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
500 server_version_string, client_version_string);
505 /* Destroy the host and server keys. They will no longer be needed. */
507 destroy_sensitive_data(void)
511 if (sensitive_data.server_key) {
512 key_free(sensitive_data.server_key);
513 sensitive_data.server_key = NULL;
515 for (i = 0; i < options.num_host_key_files; i++) {
516 if (sensitive_data.host_keys[i]) {
517 key_free(sensitive_data.host_keys[i]);
518 sensitive_data.host_keys[i] = NULL;
521 sensitive_data.ssh1_host_key = NULL;
522 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
525 /* Demote private to public keys for network child */
527 demote_sensitive_data(void)
532 if (sensitive_data.server_key) {
533 tmp = key_demote(sensitive_data.server_key);
534 key_free(sensitive_data.server_key);
535 sensitive_data.server_key = tmp;
538 for (i = 0; i < options.num_host_key_files; i++) {
539 if (sensitive_data.host_keys[i]) {
540 tmp = key_demote(sensitive_data.host_keys[i]);
541 key_free(sensitive_data.host_keys[i]);
542 sensitive_data.host_keys[i] = tmp;
543 if (tmp->type == KEY_RSA1)
544 sensitive_data.ssh1_host_key = tmp;
548 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
552 privsep_preauth_child(void)
559 /* Enable challenge-response authentication for privilege separation */
560 privsep_challenge_enable();
562 for (i = 0; i < 256; i++)
563 rnd[i] = arc4random();
564 RAND_seed(rnd, sizeof(rnd));
566 /* Demote the private keys to public keys. */
567 demote_sensitive_data();
569 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
570 fatal("Privilege separation user %s does not exist",
572 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
575 /* Change our root directory */
576 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
577 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
579 if (chdir("/") == -1)
580 fatal("chdir(\"/\"): %s", strerror(errno));
582 /* Drop our privileges */
583 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
586 /* XXX not ready, too heavy after chroot */
587 do_setusercontext(pw);
589 gidset[0] = pw->pw_gid;
590 if (setgroups(1, gidset) < 0)
591 fatal("setgroups: %.100s", strerror(errno));
592 permanently_set_uid(pw);
597 privsep_preauth(Authctxt *authctxt)
602 /* Set up unprivileged child process to deal with network data */
603 pmonitor = monitor_init();
604 /* Store a pointer to the kex for later rekeying */
605 pmonitor->m_pkex = &xxx_kex;
609 fatal("fork of unprivileged child failed");
610 } else if (pid != 0) {
611 debug2("Network child is on pid %ld", (long)pid);
613 close(pmonitor->m_recvfd);
614 pmonitor->m_pid = pid;
615 monitor_child_preauth(authctxt, pmonitor);
616 close(pmonitor->m_sendfd);
619 monitor_sync(pmonitor);
621 /* Wait for the child's exit status */
622 while (waitpid(pid, &status, 0) < 0)
629 close(pmonitor->m_sendfd);
631 /* Demote the child */
632 if (getuid() == 0 || geteuid() == 0)
633 privsep_preauth_child();
634 setproctitle("%s", "[net]");
640 privsep_postauth(Authctxt *authctxt)
642 #ifdef DISABLE_FD_PASSING
645 if (authctxt->pw->pw_uid == 0 || options.use_login) {
647 /* File descriptor passing is broken or root login */
652 /* New socket pair */
653 monitor_reinit(pmonitor);
655 pmonitor->m_pid = fork();
656 if (pmonitor->m_pid == -1)
657 fatal("fork of unprivileged child failed");
658 else if (pmonitor->m_pid != 0) {
659 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
660 close(pmonitor->m_recvfd);
661 buffer_clear(&loginmsg);
662 monitor_child_postauth(pmonitor);
668 close(pmonitor->m_sendfd);
670 /* Demote the private keys to public keys. */
671 demote_sensitive_data();
673 /* Drop privileges */
674 do_setusercontext(authctxt->pw);
677 /* It is safe now to apply the key state */
678 monitor_apply_keystate(pmonitor);
681 * Tell the packet layer that authentication was successful, since
682 * this information is not part of the key state.
684 packet_set_authenticated();
688 list_hostkey_types(void)
696 for (i = 0; i < options.num_host_key_files; i++) {
697 Key *key = sensitive_data.host_keys[i];
703 if (buffer_len(&b) > 0)
704 buffer_append(&b, ",", 1);
705 p = key_ssh_name(key);
706 buffer_append(&b, p, strlen(p));
710 buffer_append(&b, "\0", 1);
711 ret = xstrdup(buffer_ptr(&b));
713 debug("list_hostkey_types: %s", ret);
718 get_hostkey_by_type(int type)
722 for (i = 0; i < options.num_host_key_files; i++) {
723 Key *key = sensitive_data.host_keys[i];
724 if (key != NULL && key->type == type)
731 get_hostkey_by_index(int ind)
733 if (ind < 0 || ind >= options.num_host_key_files)
735 return (sensitive_data.host_keys[ind]);
739 get_hostkey_index(Key *key)
743 for (i = 0; i < options.num_host_key_files; i++) {
744 if (key == sensitive_data.host_keys[i])
751 * returns 1 if connection should be dropped, 0 otherwise.
752 * dropping starts at connection #max_startups_begin with a probability
753 * of (max_startups_rate/100). the probability increases linearly until
754 * all connections are dropped for startups > max_startups
757 drop_connection(int startups)
761 if (startups < options.max_startups_begin)
763 if (startups >= options.max_startups)
765 if (options.max_startups_rate == 100)
768 p = 100 - options.max_startups_rate;
769 p *= startups - options.max_startups_begin;
770 p /= options.max_startups - options.max_startups_begin;
771 p += options.max_startups_rate;
772 r = arc4random() % 100;
774 debug("drop_connection: p %d, r %d", p, r);
775 return (r < p) ? 1 : 0;
781 fprintf(stderr, "%s, %s\n",
782 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
784 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
785 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
791 send_rexec_state(int fd, Buffer *conf)
795 debug3("%s: entering fd = %d config len %d", __func__, fd,
799 * Protocol from reexec master to child:
800 * string configuration
801 * u_int ephemeral_key_follows
802 * bignum e (only if ephemeral_key_follows == 1)
808 * string rngseed (only if OpenSSL is not self-seeded)
811 buffer_put_cstring(&m, buffer_ptr(conf));
813 if (sensitive_data.server_key != NULL &&
814 sensitive_data.server_key->type == KEY_RSA1) {
815 buffer_put_int(&m, 1);
816 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
817 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
818 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
819 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
820 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
821 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
823 buffer_put_int(&m, 0);
825 #ifndef OPENSSL_PRNG_ONLY
826 rexec_send_rng_seed(&m);
829 if (ssh_msg_send(fd, 0, &m) == -1)
830 fatal("%s: ssh_msg_send failed", __func__);
834 debug3("%s: done", __func__);
838 recv_rexec_state(int fd, Buffer *conf)
844 debug3("%s: entering fd = %d", __func__, fd);
848 if (ssh_msg_recv(fd, &m) == -1)
849 fatal("%s: ssh_msg_recv failed", __func__);
850 if (buffer_get_char(&m) != 0)
851 fatal("%s: rexec version mismatch", __func__);
853 cp = buffer_get_string(&m, &len);
855 buffer_append(conf, cp, len + 1);
858 if (buffer_get_int(&m)) {
859 if (sensitive_data.server_key != NULL)
860 key_free(sensitive_data.server_key);
861 sensitive_data.server_key = key_new_private(KEY_RSA1);
862 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
863 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
864 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
865 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
866 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
867 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
868 rsa_generate_additional_parameters(
869 sensitive_data.server_key->rsa);
872 #ifndef OPENSSL_PRNG_ONLY
873 rexec_recv_rng_seed(&m);
878 debug3("%s: done", __func__);
882 * Main program for the daemon.
885 main(int ac, char **av)
889 int opt, j, i, fdsetsz, on = 1;
890 int sock_in = -1, sock_out = -1, newsock = -1;
894 struct sockaddr_storage from;
895 const char *remote_ip;
899 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
901 int listen_sock, maxfd;
902 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
906 int ret, key_used = 0;
909 #ifdef HAVE_SECUREWARE
910 (void)set_auth_parameters(ac, av);
912 __progname = ssh_get_progname(av[0]);
915 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
918 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
919 for (i = 0; i < ac; i++)
920 saved_argv[i] = xstrdup(av[i]);
921 saved_argv[i] = NULL;
923 #ifndef HAVE_SETPROCTITLE
924 /* Prepare for later setproctitle emulation */
925 compat_init_setproctitle(ac, av);
929 if (geteuid() == 0 && setgroups(0, NULL) == -1)
930 debug("setgroups(): %.200s", strerror(errno));
932 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
935 /* Initialize configuration options to their default values. */
936 initialize_server_options(&options);
938 /* Parse command-line arguments. */
939 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
942 options.address_family = AF_INET;
945 options.address_family = AF_INET6;
948 config_file_name = optarg;
951 if (debug_flag == 0) {
953 options.log_level = SYSLOG_LEVEL_DEBUG1;
954 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
977 options.log_level = SYSLOG_LEVEL_QUIET;
980 options.server_key_bits = atoi(optarg);
983 options.ports_from_cmdline = 1;
984 if (options.num_ports >= MAX_PORTS) {
985 fprintf(stderr, "too many ports.\n");
988 options.ports[options.num_ports++] = a2port(optarg);
989 if (options.ports[options.num_ports-1] == 0) {
990 fprintf(stderr, "Bad port number.\n");
995 if ((options.login_grace_time = convtime(optarg)) == -1) {
996 fprintf(stderr, "Invalid login grace time.\n");
1001 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1002 fprintf(stderr, "Invalid key regeneration interval.\n");
1007 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1008 fprintf(stderr, "too many host keys.\n");
1011 options.host_key_files[options.num_host_key_files++] = optarg;
1017 utmp_len = atoi(optarg);
1018 if (utmp_len > MAXHOSTNAMELEN) {
1019 fprintf(stderr, "Invalid utmp length.\n");
1024 line = xstrdup(optarg);
1025 if (process_server_config_line(&options, line,
1026 "command-line", 0) != 0)
1036 if (rexeced_flag || inetd_flag)
1038 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1039 fatal("sshd re-exec requires execution with an absolute path");
1041 closefrom(REEXEC_MIN_FREE_FD);
1043 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1045 SSLeay_add_all_algorithms();
1048 * Force logging to stderr until we have loaded the private host
1049 * key (unless started from inetd)
1051 log_init(__progname,
1052 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1053 SYSLOG_LEVEL_INFO : options.log_level,
1054 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1055 SYSLOG_FACILITY_AUTH : options.log_facility,
1056 log_stderr || !inetd_flag);
1059 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1060 * root's environment
1062 if (getenv("KRB5CCNAME") != NULL)
1063 unsetenv("KRB5CCNAME");
1066 /* Cray can define user privs drop all privs now!
1067 * Not needed on PRIV_SU systems!
1072 sensitive_data.server_key = NULL;
1073 sensitive_data.ssh1_host_key = NULL;
1074 sensitive_data.have_ssh1_key = 0;
1075 sensitive_data.have_ssh2_key = 0;
1077 /* Fetch our configuration */
1080 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1082 load_server_config(config_file_name, &cfg);
1084 parse_server_config(&options,
1085 rexeced_flag ? "rexec" : config_file_name, &cfg);
1092 /* Fill in default values for those options not explicitly set. */
1093 fill_default_server_options(&options);
1095 /* set default channel AF */
1096 channel_set_af(options.address_family);
1098 /* Check that there are no remaining arguments. */
1100 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1104 debug("sshd version %.100s", SSH_RELEASE);
1106 /* load private host keys */
1107 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1109 for (i = 0; i < options.num_host_key_files; i++)
1110 sensitive_data.host_keys[i] = NULL;
1112 for (i = 0; i < options.num_host_key_files; i++) {
1113 key = key_load_private(options.host_key_files[i], "", NULL);
1114 sensitive_data.host_keys[i] = key;
1116 error("Could not load host key: %s",
1117 options.host_key_files[i]);
1118 sensitive_data.host_keys[i] = NULL;
1121 switch (key->type) {
1123 sensitive_data.ssh1_host_key = key;
1124 sensitive_data.have_ssh1_key = 1;
1128 sensitive_data.have_ssh2_key = 1;
1131 debug("private host key: #%d type %d %s", i, key->type,
1134 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1135 logit("Disabling protocol version 1. Could not load host key");
1136 options.protocol &= ~SSH_PROTO_1;
1138 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1139 logit("Disabling protocol version 2. Could not load host key");
1140 options.protocol &= ~SSH_PROTO_2;
1142 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1143 logit("sshd: no hostkeys available -- exiting.");
1147 /* Check certain values for sanity. */
1148 if (options.protocol & SSH_PROTO_1) {
1149 if (options.server_key_bits < 512 ||
1150 options.server_key_bits > 32768) {
1151 fprintf(stderr, "Bad server key size.\n");
1155 * Check that server and host key lengths differ sufficiently. This
1156 * is necessary to make double encryption work with rsaref. Oh, I
1157 * hate software patents. I dont know if this can go? Niels
1159 if (options.server_key_bits >
1160 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1161 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1162 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1163 SSH_KEY_BITS_RESERVED) {
1164 options.server_key_bits =
1165 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1166 SSH_KEY_BITS_RESERVED;
1167 debug("Forcing server key to %d bits to make it differ from host key.",
1168 options.server_key_bits);
1176 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1177 fatal("Privilege separation user %s does not exist",
1179 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1180 (S_ISDIR(st.st_mode) == 0))
1181 fatal("Missing privilege separation directory: %s",
1182 _PATH_PRIVSEP_CHROOT_DIR);
1185 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1186 (st.st_uid != getuid () ||
1187 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1189 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1191 fatal("%s must be owned by root and not group or "
1192 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1195 /* Configuration looks good, so exit if in test mode. */
1200 * Clear out any supplemental groups we may have inherited. This
1201 * prevents inadvertent creation of files with bad modes (in the
1202 * portable version at least, it's certainly possible for PAM
1203 * to create a file, and we can't control the code in every
1204 * module which might be used).
1206 if (setgroups(0, NULL) < 0)
1207 debug("setgroups() failed: %.200s", strerror(errno));
1210 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1211 for (i = 0; i < rexec_argc; i++) {
1212 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1213 rexec_argv[i] = saved_argv[i];
1215 rexec_argv[rexec_argc] = "-R";
1216 rexec_argv[rexec_argc + 1] = NULL;
1219 /* Initialize the log (it is reinitialized below in case we forked). */
1220 if (debug_flag && (!inetd_flag || rexeced_flag))
1222 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1225 * If not in debugging mode, and not started from inetd, disconnect
1226 * from the controlling terminal, and fork. The original process
1229 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1232 #endif /* TIOCNOTTY */
1233 if (daemon(0, 0) < 0)
1234 fatal("daemon() failed: %.200s", strerror(errno));
1236 /* Disconnect from the controlling tty. */
1238 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1240 (void) ioctl(fd, TIOCNOTTY, NULL);
1243 #endif /* TIOCNOTTY */
1245 /* Reinitialize the log (because of the fork above). */
1246 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1248 /* Initialize the random number generator. */
1251 /* Chdir to the root directory so that the current disk can be
1252 unmounted if desired. */
1255 /* ignore SIGPIPE */
1256 signal(SIGPIPE, SIG_IGN);
1258 /* Start listening for a socket, unless started from inetd. */
1264 close(REEXEC_CONFIG_PASS_FD);
1265 sock_in = sock_out = dup(STDIN_FILENO);
1267 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1268 close(REEXEC_STARTUP_PIPE_FD);
1271 sock_in = dup(STDIN_FILENO);
1272 sock_out = dup(STDOUT_FILENO);
1275 * We intentionally do not close the descriptors 0, 1, and 2
1276 * as our code for setting the descriptors won't work if
1277 * ttyfd happens to be one of those.
1279 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1280 dup2(fd, STDIN_FILENO);
1281 dup2(fd, STDOUT_FILENO);
1282 if (fd > STDOUT_FILENO)
1285 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1286 if ((options.protocol & SSH_PROTO_1) &&
1287 sensitive_data.server_key == NULL)
1288 generate_ephemeral_server_key();
1290 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1291 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1293 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1294 fatal("Too many listen sockets. "
1295 "Enlarge MAX_LISTEN_SOCKS");
1296 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1297 ntop, sizeof(ntop), strport, sizeof(strport),
1298 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1299 error("getnameinfo failed: %.100s",
1300 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1304 /* Create socket for listening. */
1305 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1307 if (listen_sock < 0) {
1308 /* kernel may not support ipv6 */
1309 verbose("socket: %.100s", strerror(errno));
1312 if (set_nonblock(listen_sock) == -1) {
1317 * Set socket options.
1318 * Allow local port reuse in TIME_WAIT.
1320 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1321 &on, sizeof(on)) == -1)
1322 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1324 debug("Bind to port %s on %s.", strport, ntop);
1326 /* Bind the socket to the desired port. */
1327 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1329 error("Bind to port %s on %s failed: %.200s.",
1330 strport, ntop, strerror(errno));
1334 listen_socks[num_listen_socks] = listen_sock;
1337 /* Start listening on the port. */
1338 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1339 fatal("listen on [%s]:%s: %.100s",
1340 ntop, strport, strerror(errno));
1341 logit("Server listening on %s port %s.", ntop, strport);
1343 freeaddrinfo(options.listen_addrs);
1345 if (!num_listen_socks)
1346 fatal("Cannot bind any address.");
1348 if (options.protocol & SSH_PROTO_1)
1349 generate_ephemeral_server_key();
1352 * Arrange to restart on SIGHUP. The handler needs
1355 signal(SIGHUP, sighup_handler);
1357 signal(SIGTERM, sigterm_handler);
1358 signal(SIGQUIT, sigterm_handler);
1360 /* Arrange SIGCHLD to be caught. */
1361 signal(SIGCHLD, main_sigchld_handler);
1363 /* Write out the pid file after the sigterm handler is setup */
1366 * Record our pid in /var/run/sshd.pid to make it
1367 * easier to kill the correct sshd. We don't want to
1368 * do this before the bind above because the bind will
1369 * fail if there already is a daemon, and this will
1370 * overwrite any old pid in the file.
1372 f = fopen(options.pid_file, "wb");
1374 error("Couldn't create pid file \"%s\": %s",
1375 options.pid_file, strerror(errno));
1377 fprintf(f, "%ld\n", (long) getpid());
1382 /* setup fd set for listen */
1385 for (i = 0; i < num_listen_socks; i++)
1386 if (listen_socks[i] > maxfd)
1387 maxfd = listen_socks[i];
1388 /* pipes connected to unauthenticated childs */
1389 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1390 for (i = 0; i < options.max_startups; i++)
1391 startup_pipes[i] = -1;
1394 * Stay listening for connections until the system crashes or
1395 * the daemon is killed with a signal.
1398 if (received_sighup)
1402 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1403 fdset = (fd_set *)xmalloc(fdsetsz);
1404 memset(fdset, 0, fdsetsz);
1406 for (i = 0; i < num_listen_socks; i++)
1407 FD_SET(listen_socks[i], fdset);
1408 for (i = 0; i < options.max_startups; i++)
1409 if (startup_pipes[i] != -1)
1410 FD_SET(startup_pipes[i], fdset);
1412 /* Wait in select until there is a connection. */
1413 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1414 if (ret < 0 && errno != EINTR)
1415 error("select: %.100s", strerror(errno));
1416 if (received_sigterm) {
1417 logit("Received signal %d; terminating.",
1418 (int) received_sigterm);
1419 close_listen_socks();
1420 unlink(options.pid_file);
1423 if (key_used && key_do_regen) {
1424 generate_ephemeral_server_key();
1431 for (i = 0; i < options.max_startups; i++)
1432 if (startup_pipes[i] != -1 &&
1433 FD_ISSET(startup_pipes[i], fdset)) {
1435 * the read end of the pipe is ready
1436 * if the child has closed the pipe
1437 * after successful authentication
1438 * or if the child has died
1440 close(startup_pipes[i]);
1441 startup_pipes[i] = -1;
1444 for (i = 0; i < num_listen_socks; i++) {
1445 if (!FD_ISSET(listen_socks[i], fdset))
1447 fromlen = sizeof(from);
1448 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1451 if (errno != EINTR && errno != EWOULDBLOCK)
1452 error("accept: %.100s", strerror(errno));
1455 if (unset_nonblock(newsock) == -1) {
1459 if (drop_connection(startups) == 1) {
1460 debug("drop connection #%d", startups);
1464 if (pipe(startup_p) == -1) {
1469 if (rexec_flag && socketpair(AF_UNIX,
1470 SOCK_STREAM, 0, config_s) == -1) {
1471 error("reexec socketpair: %s",
1474 close(startup_p[0]);
1475 close(startup_p[1]);
1479 for (j = 0; j < options.max_startups; j++)
1480 if (startup_pipes[j] == -1) {
1481 startup_pipes[j] = startup_p[0];
1482 if (maxfd < startup_p[0])
1483 maxfd = startup_p[0];
1489 * Got connection. Fork a child to handle it, unless
1490 * we are in debugging mode.
1494 * In debugging mode. Close the listening
1495 * socket, and start processing the
1496 * connection without forking.
1498 debug("Server will not fork when running in debugging mode.");
1499 close_listen_socks();
1502 close(startup_p[0]);
1503 close(startup_p[1]);
1507 send_rexec_state(config_s[0],
1514 * Normal production daemon. Fork, and have
1515 * the child process the connection. The
1516 * parent continues listening.
1518 if ((pid = fork()) == 0) {
1520 * Child. Close the listening and max_startup
1521 * sockets. Start using the accepted socket.
1522 * Reinitialize logging (since our pid has
1523 * changed). We break out of the loop to handle
1526 startup_pipe = startup_p[1];
1527 close_startup_pipes();
1528 close_listen_socks();
1531 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1538 /* Parent. Stay in the loop. */
1540 error("fork: %.100s", strerror(errno));
1542 debug("Forked child %ld.", (long)pid);
1544 close(startup_p[1]);
1547 send_rexec_state(config_s[0], &cfg);
1552 /* Mark that the key has been used (it was "given" to the child). */
1553 if ((options.protocol & SSH_PROTO_1) &&
1555 /* Schedule server key regeneration alarm. */
1556 signal(SIGALRM, key_regeneration_alarm);
1557 alarm(options.key_regeneration_time);
1563 /* Close the new socket (the child is now taking care of it). */
1566 /* child process check (or debug mode) */
1567 if (num_listen_socks < 0)
1572 /* This is the child processing a new connection. */
1573 setproctitle("%s", "[accepted]");
1576 * Create a new session and process group since the 4.4BSD
1577 * setlogin() affects the entire process group. We don't
1578 * want the child to be able to affect the parent.
1580 #if !defined(SSHD_ACQUIRES_CTTY)
1582 * If setsid is called, on some platforms sshd will later acquire a
1583 * controlling terminal which will result in "could not set
1584 * controlling tty" errors.
1586 if (!debug_flag && !inetd_flag && setsid() < 0)
1587 error("setsid: %.100s", strerror(errno));
1593 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1594 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1595 dup2(newsock, STDIN_FILENO);
1596 dup2(STDIN_FILENO, STDOUT_FILENO);
1597 if (startup_pipe == -1)
1598 close(REEXEC_STARTUP_PIPE_FD);
1600 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1602 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1604 if (startup_pipe != -1)
1605 close(startup_pipe);
1607 execv(rexec_argv[0], rexec_argv);
1609 /* Reexec has failed, fall back and continue */
1610 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1611 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1612 log_init(__progname, options.log_level,
1613 options.log_facility, log_stderr);
1616 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1618 close(REEXEC_CONFIG_PASS_FD);
1619 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1620 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1621 dup2(fd, STDIN_FILENO);
1622 dup2(fd, STDOUT_FILENO);
1623 if (fd > STDERR_FILENO)
1626 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1627 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1631 * Disable the key regeneration alarm. We will not regenerate the
1632 * key since we are no longer in a position to give it to anyone. We
1633 * will not restart on SIGHUP since it no longer makes sense.
1636 signal(SIGALRM, SIG_DFL);
1637 signal(SIGHUP, SIG_DFL);
1638 signal(SIGTERM, SIG_DFL);
1639 signal(SIGQUIT, SIG_DFL);
1640 signal(SIGCHLD, SIG_DFL);
1641 signal(SIGINT, SIG_DFL);
1644 * Register our connection. This turns encryption off because we do
1647 packet_set_connection(sock_in, sock_out);
1648 packet_set_server();
1650 /* Set SO_KEEPALIVE if requested. */
1651 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1652 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1653 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1655 if ((remote_port = get_remote_port()) < 0) {
1656 debug("get_remote_port failed");
1661 * We use get_canonical_hostname with usedns = 0 instead of
1662 * get_remote_ipaddr here so IP options will be checked.
1664 remote_ip = get_canonical_hostname(0);
1666 #ifdef SSH_AUDIT_EVENTS
1667 audit_connection_from(remote_ip, remote_port);
1670 /* Check whether logins are denied from this host. */
1671 if (packet_connection_is_on_socket()) {
1672 struct request_info req;
1674 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1677 if (!hosts_access(&req)) {
1678 debug("Connection refused by tcp wrapper");
1681 fatal("libwrap refuse returns");
1684 #endif /* LIBWRAP */
1686 /* Log the connection. */
1687 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1690 * We don't want to listen forever unless the other side
1691 * successfully authenticates itself. So we set up an alarm which is
1692 * cleared after successful authentication. A limit of zero
1693 * indicates no limit. Note that we don't set the alarm in debugging
1694 * mode; it is just annoying to have the server exit just when you
1695 * are about to discover the bug.
1697 signal(SIGALRM, grace_alarm_handler);
1699 alarm(options.login_grace_time);
1701 sshd_exchange_identification(sock_in, sock_out);
1703 packet_set_nonblocking();
1705 /* allocate authentication context */
1706 authctxt = xmalloc(sizeof(*authctxt));
1707 memset(authctxt, 0, sizeof(*authctxt));
1709 authctxt->loginmsg = &loginmsg;
1711 /* XXX global for cleanup, access from other modules */
1712 the_authctxt = authctxt;
1714 /* prepare buffer to collect messages to display to user after login */
1715 buffer_init(&loginmsg);
1718 if (privsep_preauth(authctxt) == 1)
1721 /* perform the key exchange */
1722 /* authenticate user and start session */
1725 do_authentication2(authctxt);
1728 do_authentication(authctxt);
1731 * If we use privilege separation, the unprivileged child transfers
1732 * the current keystate and exits
1735 mm_send_keystate(pmonitor);
1741 * Cancel the alarm we set to limit the time taken for
1745 signal(SIGALRM, SIG_DFL);
1746 if (startup_pipe != -1) {
1747 close(startup_pipe);
1751 #ifdef SSH_AUDIT_EVENTS
1752 audit_event(SSH_AUTH_SUCCESS);
1756 * In privilege separation, we fork another child and prepare
1757 * file descriptor passing.
1760 privsep_postauth(authctxt);
1761 /* the monitor process [priv] will not return */
1763 destroy_sensitive_data();
1766 /* Start session. */
1767 do_authenticated(authctxt);
1769 /* The connection has been terminated. */
1770 verbose("Closing connection to %.100s", remote_ip);
1773 if (options.use_pam)
1775 #endif /* USE_PAM */
1777 #ifdef SSH_AUDIT_EVENTS
1778 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1790 * Decrypt session_key_int using our private server key and private host key
1791 * (key with larger modulus first).
1794 ssh1_session_key(BIGNUM *session_key_int)
1798 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1799 /* Server key has bigger modulus. */
1800 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1801 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1802 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1803 get_remote_ipaddr(),
1804 BN_num_bits(sensitive_data.server_key->rsa->n),
1805 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1806 SSH_KEY_BITS_RESERVED);
1808 if (rsa_private_decrypt(session_key_int, session_key_int,
1809 sensitive_data.server_key->rsa) <= 0)
1811 if (rsa_private_decrypt(session_key_int, session_key_int,
1812 sensitive_data.ssh1_host_key->rsa) <= 0)
1815 /* Host key has bigger modulus (or they are equal). */
1816 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1817 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1818 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1819 get_remote_ipaddr(),
1820 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1821 BN_num_bits(sensitive_data.server_key->rsa->n),
1822 SSH_KEY_BITS_RESERVED);
1824 if (rsa_private_decrypt(session_key_int, session_key_int,
1825 sensitive_data.ssh1_host_key->rsa) < 0)
1827 if (rsa_private_decrypt(session_key_int, session_key_int,
1828 sensitive_data.server_key->rsa) < 0)
1841 BIGNUM *session_key_int;
1842 u_char session_key[SSH_SESSION_KEY_LENGTH];
1844 u_int cipher_type, auth_mask, protocol_flags;
1848 * Generate check bytes that the client must send back in the user
1849 * packet in order for it to be accepted; this is used to defy ip
1850 * spoofing attacks. Note that this only works against somebody
1851 * doing IP spoofing from a remote machine; any machine on the local
1852 * network can still see outgoing packets and catch the random
1853 * cookie. This only affects rhosts authentication, and this is one
1854 * of the reasons why it is inherently insecure.
1856 for (i = 0; i < 8; i++) {
1859 cookie[i] = rnd & 0xff;
1864 * Send our public key. We include in the packet 64 bits of random
1865 * data that must be matched in the reply in order to prevent IP
1868 packet_start(SSH_SMSG_PUBLIC_KEY);
1869 for (i = 0; i < 8; i++)
1870 packet_put_char(cookie[i]);
1872 /* Store our public server RSA key. */
1873 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1874 packet_put_bignum(sensitive_data.server_key->rsa->e);
1875 packet_put_bignum(sensitive_data.server_key->rsa->n);
1877 /* Store our public host RSA key. */
1878 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1879 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1880 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1882 /* Put protocol flags. */
1883 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1885 /* Declare which ciphers we support. */
1886 packet_put_int(cipher_mask_ssh1(0));
1888 /* Declare supported authentication types. */
1890 if (options.rhosts_rsa_authentication)
1891 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1892 if (options.rsa_authentication)
1893 auth_mask |= 1 << SSH_AUTH_RSA;
1894 if (options.challenge_response_authentication == 1)
1895 auth_mask |= 1 << SSH_AUTH_TIS;
1896 if (options.password_authentication)
1897 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1898 packet_put_int(auth_mask);
1900 /* Send the packet and wait for it to be sent. */
1902 packet_write_wait();
1904 debug("Sent %d bit server key and %d bit host key.",
1905 BN_num_bits(sensitive_data.server_key->rsa->n),
1906 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1908 /* Read clients reply (cipher type and session key). */
1909 packet_read_expect(SSH_CMSG_SESSION_KEY);
1911 /* Get cipher type and check whether we accept this. */
1912 cipher_type = packet_get_char();
1914 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1915 packet_disconnect("Warning: client selects unsupported cipher.");
1917 /* Get check bytes from the packet. These must match those we
1918 sent earlier with the public key packet. */
1919 for (i = 0; i < 8; i++)
1920 if (cookie[i] != packet_get_char())
1921 packet_disconnect("IP Spoofing check bytes do not match.");
1923 debug("Encryption type: %.200s", cipher_name(cipher_type));
1925 /* Get the encrypted integer. */
1926 if ((session_key_int = BN_new()) == NULL)
1927 fatal("do_ssh1_kex: BN_new failed");
1928 packet_get_bignum(session_key_int);
1930 protocol_flags = packet_get_int();
1931 packet_set_protocol_flags(protocol_flags);
1934 /* Decrypt session_key_int using host/server keys */
1935 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1938 * Extract session key from the decrypted integer. The key is in the
1939 * least significant 256 bits of the integer; the first byte of the
1940 * key is in the highest bits.
1943 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1944 len = BN_num_bytes(session_key_int);
1945 if (len < 0 || (u_int)len > sizeof(session_key)) {
1946 error("do_connection: bad session key len from %s: "
1947 "session_key_int %d > sizeof(session_key) %lu",
1948 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1951 memset(session_key, 0, sizeof(session_key));
1952 BN_bn2bin(session_key_int,
1953 session_key + sizeof(session_key) - len);
1955 derive_ssh1_session_id(
1956 sensitive_data.ssh1_host_key->rsa->n,
1957 sensitive_data.server_key->rsa->n,
1958 cookie, session_id);
1960 * Xor the first 16 bytes of the session key with the
1963 for (i = 0; i < 16; i++)
1964 session_key[i] ^= session_id[i];
1968 int bytes = BN_num_bytes(session_key_int);
1969 u_char *buf = xmalloc(bytes);
1972 logit("do_connection: generating a fake encryption key");
1973 BN_bn2bin(session_key_int, buf);
1975 MD5_Update(&md, buf, bytes);
1976 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1977 MD5_Final(session_key, &md);
1979 MD5_Update(&md, session_key, 16);
1980 MD5_Update(&md, buf, bytes);
1981 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1982 MD5_Final(session_key + 16, &md);
1983 memset(buf, 0, bytes);
1985 for (i = 0; i < 16; i++)
1986 session_id[i] = session_key[i] ^ session_key[i + 16];
1988 /* Destroy the private and public keys. No longer. */
1989 destroy_sensitive_data();
1992 mm_ssh1_session_id(session_id);
1994 /* Destroy the decrypted integer. It is no longer needed. */
1995 BN_clear_free(session_key_int);
1997 /* Set the session key. From this on all communications will be encrypted. */
1998 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2000 /* Destroy our copy of the session key. It is no longer needed. */
2001 memset(session_key, 0, sizeof(session_key));
2003 debug("Received session key; encryption turned on.");
2005 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2006 packet_start(SSH_SMSG_SUCCESS);
2008 packet_write_wait();
2012 * SSH2 key exchange: diffie-hellman-group1-sha1
2019 if (options.ciphers != NULL) {
2020 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2021 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2023 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2024 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2025 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2026 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2028 if (options.macs != NULL) {
2029 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2030 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2032 if (options.compression == COMP_NONE) {
2033 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2034 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2035 } else if (options.compression == COMP_DELAYED) {
2036 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2037 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2040 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2042 /* start key exchange */
2043 kex = kex_setup(myproposal);
2044 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2045 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2046 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2047 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2049 kex->client_version_string=client_version_string;
2050 kex->server_version_string=server_version_string;
2051 kex->load_host_key=&get_hostkey_by_type;
2052 kex->host_key_index=&get_hostkey_index;
2056 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2058 session_id2 = kex->session_id;
2059 session_id2_len = kex->session_id_len;
2062 /* send 1st encrypted/maced/compressed message */
2063 packet_start(SSH2_MSG_IGNORE);
2064 packet_put_cstring("markus");
2066 packet_write_wait();
2071 /* server specific fatal cleanup */
2076 do_cleanup(the_authctxt);
2077 #ifdef SSH_AUDIT_EVENTS
2078 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2079 if (!use_privsep || mm_is_monitor())
2080 audit_event(SSH_CONNECTION_ABANDON);