1 /* $OpenBSD: sshd.c,v 1.347 2006/08/18 09:15:20 markus Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This program is the ssh daemon. It listens for connections from clients,
7 * and performs authentication, executes use commands or shell, and forwards
8 * information to/from the application to the user client over an encrypted
9 * connection. This can also handle forwarding of X11, TCP/IP, and
10 * authentication agent connections.
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
18 * SSH2 implementation:
19 * Privilege Separation:
21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22 * Copyright (c) 2002 Niels Provos. All rights reserved.
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
47 #include <sys/types.h>
48 #include <sys/ioctl.h>
49 #include <sys/socket.h>
50 #ifdef HAVE_SYS_STAT_H
51 # include <sys/stat.h>
53 #ifdef HAVE_SYS_TIME_H
54 # include <sys/time.h>
56 #include "openbsd-compat/sys-tree.h"
74 #include <openssl/dh.h>
75 #include <openssl/bn.h>
76 #include <openssl/md5.h>
77 #include <openssl/rand.h>
78 #ifdef HAVE_SECUREWARE
79 #include <sys/security.h>
99 #include "myproposal.h"
100 #include "authfile.h"
101 #include "pathnames.h"
102 #include "atomicio.h"
103 #include "canohost.h"
104 #include "hostfile.h"
108 #include "dispatch.h"
109 #include "channels.h"
111 #include "monitor_mm.h"
116 #include "monitor_wrap.h"
117 #include "monitor_fdpass.h"
123 int allow_severity = LOG_INFO;
124 int deny_severity = LOG_WARNING;
132 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
133 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
134 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
135 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
137 extern char *__progname;
139 /* Server configuration options. */
140 ServerOptions options;
142 /* Name of the server configuration file. */
143 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
146 * Debug mode flag. This can be set on the command line. If debug
147 * mode is enabled, extra debugging output will be sent to the system
148 * log, the daemon will not go to background, and will exit after processing
149 * the first connection.
153 /* Flag indicating that the daemon should only test the configuration and keys. */
156 /* Flag indicating that the daemon is being started from inetd. */
159 /* Flag indicating that sshd should not detach and become a daemon. */
160 int no_daemon_flag = 0;
162 /* debug goes to stderr unless inetd_flag is set */
165 /* Saved arguments to main(). */
170 int rexeced_flag = 0;
176 * The sockets that the server is listening; this is used in the SIGHUP
179 #define MAX_LISTEN_SOCKS 16
180 int listen_socks[MAX_LISTEN_SOCKS];
181 int num_listen_socks = 0;
184 * the client's version string, passed by sshd2 in compat mode. if != NULL,
185 * sshd will skip the version-number exchange
187 char *client_version_string = NULL;
188 char *server_version_string = NULL;
190 /* for rekeying XXX fixme */
194 * Any really sensitive data in the application is contained in this
195 * structure. The idea is that this structure could be locked into memory so
196 * that the pages do not get written into swap. However, there are some
197 * problems. The private key contains BIGNUMs, and we do not (in principle)
198 * have access to the internals of them, and locking just the structure is
199 * not very useful. Currently, memory locking is not implemented.
202 Key *server_key; /* ephemeral server key */
203 Key *ssh1_host_key; /* ssh1 host key */
204 Key **host_keys; /* all private host keys */
207 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
211 * Flag indicating whether the RSA server key needs to be regenerated.
212 * Is set in the SIGALRM handler and cleared when the key is regenerated.
214 static volatile sig_atomic_t key_do_regen = 0;
216 /* This is set to true when a signal is received. */
217 static volatile sig_atomic_t received_sighup = 0;
218 static volatile sig_atomic_t received_sigterm = 0;
220 /* session identifier, used by RSA-auth */
221 u_char session_id[16];
224 u_char *session_id2 = NULL;
225 u_int session_id2_len = 0;
227 /* record remote hostname or ip */
228 u_int utmp_len = MAXHOSTNAMELEN;
230 /* options.max_startup sized array of fd ints */
231 int *startup_pipes = NULL;
232 int startup_pipe; /* in child */
234 /* variables used for privilege separation */
235 int use_privsep = -1;
236 struct monitor *pmonitor = NULL;
238 /* global authentication context */
239 Authctxt *the_authctxt = NULL;
241 /* sshd_config buffer */
244 /* message to be displayed after login */
247 /* Unprivileged user */
248 struct passwd *privsep_pw = NULL;
250 /* Prototypes for various functions defined later in this file. */
251 void destroy_sensitive_data(void);
252 void demote_sensitive_data(void);
254 static void do_ssh1_kex(void);
255 static void do_ssh2_kex(void);
258 * Close all listening sockets
261 close_listen_socks(void)
265 for (i = 0; i < num_listen_socks; i++)
266 close(listen_socks[i]);
267 num_listen_socks = -1;
271 close_startup_pipes(void)
276 for (i = 0; i < options.max_startups; i++)
277 if (startup_pipes[i] != -1)
278 close(startup_pipes[i]);
282 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
283 * the effect is to reread the configuration file (and to regenerate
289 sighup_handler(int sig)
291 int save_errno = errno;
294 signal(SIGHUP, sighup_handler);
299 * Called from the main program after receiving SIGHUP.
300 * Restarts the server.
305 logit("Received SIGHUP; restarting.");
306 close_listen_socks();
307 close_startup_pipes();
308 execv(saved_argv[0], saved_argv);
309 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
315 * Generic signal handler for terminating signals in the master daemon.
319 sigterm_handler(int sig)
321 received_sigterm = sig;
325 * SIGCHLD handler. This is called whenever a child dies. This will then
326 * reap any zombies left by exited children.
330 main_sigchld_handler(int sig)
332 int save_errno = errno;
336 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
337 (pid < 0 && errno == EINTR))
340 signal(SIGCHLD, main_sigchld_handler);
345 * Signal handler for the alarm after the login grace period has expired.
349 grace_alarm_handler(int sig)
351 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
352 kill(pmonitor->m_pid, SIGALRM);
354 /* Log error and exit. */
355 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
359 * Signal handler for the key regeneration alarm. Note that this
360 * alarm only occurs in the daemon waiting for connections, and it does not
361 * do anything with the private key or random state before forking.
362 * Thus there should be no concurrency control/asynchronous execution
366 generate_ephemeral_server_key(void)
371 verbose("Generating %s%d bit RSA key.",
372 sensitive_data.server_key ? "new " : "", options.server_key_bits);
373 if (sensitive_data.server_key != NULL)
374 key_free(sensitive_data.server_key);
375 sensitive_data.server_key = key_generate(KEY_RSA1,
376 options.server_key_bits);
377 verbose("RSA key generation complete.");
379 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
382 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
390 key_regeneration_alarm(int sig)
392 int save_errno = errno;
394 signal(SIGALRM, SIG_DFL);
400 sshd_exchange_identification(int sock_in, int sock_out)
404 int remote_major, remote_minor;
407 char buf[256]; /* Must not be larger than remote_version. */
408 char remote_version[256]; /* Must be at least as big as buf. */
410 if ((options.protocol & SSH_PROTO_1) &&
411 (options.protocol & SSH_PROTO_2)) {
412 major = PROTOCOL_MAJOR_1;
414 } else if (options.protocol & SSH_PROTO_2) {
415 major = PROTOCOL_MAJOR_2;
416 minor = PROTOCOL_MINOR_2;
418 major = PROTOCOL_MAJOR_1;
419 minor = PROTOCOL_MINOR_1;
421 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
422 server_version_string = xstrdup(buf);
424 /* Send our protocol version identification. */
425 if (atomicio(vwrite, sock_out, server_version_string,
426 strlen(server_version_string))
427 != strlen(server_version_string)) {
428 logit("Could not write ident string to %s", get_remote_ipaddr());
432 /* Read other sides version identification. */
433 memset(buf, 0, sizeof(buf));
434 for (i = 0; i < sizeof(buf) - 1; i++) {
435 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
436 logit("Did not receive identification string from %s",
437 get_remote_ipaddr());
440 if (buf[i] == '\r') {
442 /* Kludge for F-Secure Macintosh < 1.0.2 */
444 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
448 if (buf[i] == '\n') {
453 buf[sizeof(buf) - 1] = 0;
454 client_version_string = xstrdup(buf);
457 * Check that the versions match. In future this might accept
458 * several versions and set appropriate flags to handle them.
460 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
461 &remote_major, &remote_minor, remote_version) != 3) {
462 s = "Protocol mismatch.\n";
463 (void) atomicio(vwrite, sock_out, s, strlen(s));
466 logit("Bad protocol version identification '%.100s' from %s",
467 client_version_string, get_remote_ipaddr());
470 debug("Client protocol version %d.%d; client software version %.100s",
471 remote_major, remote_minor, remote_version);
473 compat_datafellows(remote_version);
475 if (datafellows & SSH_BUG_PROBE) {
476 logit("probed from %s with %s. Don't panic.",
477 get_remote_ipaddr(), client_version_string);
481 if (datafellows & SSH_BUG_SCANNER) {
482 logit("scanned from %s with %s. Don't panic.",
483 get_remote_ipaddr(), client_version_string);
488 switch (remote_major) {
490 if (remote_minor == 99) {
491 if (options.protocol & SSH_PROTO_2)
497 if (!(options.protocol & SSH_PROTO_1)) {
501 if (remote_minor < 3) {
502 packet_disconnect("Your ssh version is too old and "
503 "is no longer supported. Please install a newer version.");
504 } else if (remote_minor == 3) {
505 /* note that this disables agent-forwarding */
510 if (options.protocol & SSH_PROTO_2) {
519 chop(server_version_string);
520 debug("Local version string %.200s", server_version_string);
523 s = "Protocol major versions differ.\n";
524 (void) atomicio(vwrite, sock_out, s, strlen(s));
527 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
529 server_version_string, client_version_string);
534 /* Destroy the host and server keys. They will no longer be needed. */
536 destroy_sensitive_data(void)
540 if (sensitive_data.server_key) {
541 key_free(sensitive_data.server_key);
542 sensitive_data.server_key = NULL;
544 for (i = 0; i < options.num_host_key_files; i++) {
545 if (sensitive_data.host_keys[i]) {
546 key_free(sensitive_data.host_keys[i]);
547 sensitive_data.host_keys[i] = NULL;
550 sensitive_data.ssh1_host_key = NULL;
551 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
554 /* Demote private to public keys for network child */
556 demote_sensitive_data(void)
561 if (sensitive_data.server_key) {
562 tmp = key_demote(sensitive_data.server_key);
563 key_free(sensitive_data.server_key);
564 sensitive_data.server_key = tmp;
567 for (i = 0; i < options.num_host_key_files; i++) {
568 if (sensitive_data.host_keys[i]) {
569 tmp = key_demote(sensitive_data.host_keys[i]);
570 key_free(sensitive_data.host_keys[i]);
571 sensitive_data.host_keys[i] = tmp;
572 if (tmp->type == KEY_RSA1)
573 sensitive_data.ssh1_host_key = tmp;
577 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
581 privsep_preauth_child(void)
587 /* Enable challenge-response authentication for privilege separation */
588 privsep_challenge_enable();
590 for (i = 0; i < 256; i++)
591 rnd[i] = arc4random();
592 RAND_seed(rnd, sizeof(rnd));
594 /* Demote the private keys to public keys. */
595 demote_sensitive_data();
597 /* Change our root directory */
598 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
599 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
601 if (chdir("/") == -1)
602 fatal("chdir(\"/\"): %s", strerror(errno));
604 /* Drop our privileges */
605 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
606 (u_int)privsep_pw->pw_gid);
608 /* XXX not ready, too heavy after chroot */
609 do_setusercontext(privsep_pw);
611 gidset[0] = privsep_pw->pw_gid;
612 if (setgroups(1, gidset) < 0)
613 fatal("setgroups: %.100s", strerror(errno));
614 permanently_set_uid(privsep_pw);
619 privsep_preauth(Authctxt *authctxt)
624 /* Set up unprivileged child process to deal with network data */
625 pmonitor = monitor_init();
626 /* Store a pointer to the kex for later rekeying */
627 pmonitor->m_pkex = &xxx_kex;
631 fatal("fork of unprivileged child failed");
632 } else if (pid != 0) {
633 debug2("Network child is on pid %ld", (long)pid);
635 close(pmonitor->m_recvfd);
636 pmonitor->m_pid = pid;
637 monitor_child_preauth(authctxt, pmonitor);
638 close(pmonitor->m_sendfd);
641 monitor_sync(pmonitor);
643 /* Wait for the child's exit status */
644 while (waitpid(pid, &status, 0) < 0)
651 close(pmonitor->m_sendfd);
653 /* Demote the child */
654 if (getuid() == 0 || geteuid() == 0)
655 privsep_preauth_child();
656 setproctitle("%s", "[net]");
662 privsep_postauth(Authctxt *authctxt)
664 #ifdef DISABLE_FD_PASSING
667 if (authctxt->pw->pw_uid == 0 || options.use_login) {
669 /* File descriptor passing is broken or root login */
674 /* New socket pair */
675 monitor_reinit(pmonitor);
677 pmonitor->m_pid = fork();
678 if (pmonitor->m_pid == -1)
679 fatal("fork of unprivileged child failed");
680 else if (pmonitor->m_pid != 0) {
681 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
682 close(pmonitor->m_recvfd);
683 buffer_clear(&loginmsg);
684 monitor_child_postauth(pmonitor);
690 close(pmonitor->m_sendfd);
692 /* Demote the private keys to public keys. */
693 demote_sensitive_data();
695 /* Drop privileges */
696 do_setusercontext(authctxt->pw);
699 /* It is safe now to apply the key state */
700 monitor_apply_keystate(pmonitor);
703 * Tell the packet layer that authentication was successful, since
704 * this information is not part of the key state.
706 packet_set_authenticated();
710 list_hostkey_types(void)
718 for (i = 0; i < options.num_host_key_files; i++) {
719 Key *key = sensitive_data.host_keys[i];
725 if (buffer_len(&b) > 0)
726 buffer_append(&b, ",", 1);
727 p = key_ssh_name(key);
728 buffer_append(&b, p, strlen(p));
732 buffer_append(&b, "\0", 1);
733 ret = xstrdup(buffer_ptr(&b));
735 debug("list_hostkey_types: %s", ret);
740 get_hostkey_by_type(int type)
744 for (i = 0; i < options.num_host_key_files; i++) {
745 Key *key = sensitive_data.host_keys[i];
746 if (key != NULL && key->type == type)
753 get_hostkey_by_index(int ind)
755 if (ind < 0 || ind >= options.num_host_key_files)
757 return (sensitive_data.host_keys[ind]);
761 get_hostkey_index(Key *key)
765 for (i = 0; i < options.num_host_key_files; i++) {
766 if (key == sensitive_data.host_keys[i])
773 * returns 1 if connection should be dropped, 0 otherwise.
774 * dropping starts at connection #max_startups_begin with a probability
775 * of (max_startups_rate/100). the probability increases linearly until
776 * all connections are dropped for startups > max_startups
779 drop_connection(int startups)
783 if (startups < options.max_startups_begin)
785 if (startups >= options.max_startups)
787 if (options.max_startups_rate == 100)
790 p = 100 - options.max_startups_rate;
791 p *= startups - options.max_startups_begin;
792 p /= options.max_startups - options.max_startups_begin;
793 p += options.max_startups_rate;
794 r = arc4random() % 100;
796 debug("drop_connection: p %d, r %d", p, r);
797 return (r < p) ? 1 : 0;
803 fprintf(stderr, "%s, %s\n",
804 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
806 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
807 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
813 send_rexec_state(int fd, Buffer *conf)
817 debug3("%s: entering fd = %d config len %d", __func__, fd,
821 * Protocol from reexec master to child:
822 * string configuration
823 * u_int ephemeral_key_follows
824 * bignum e (only if ephemeral_key_follows == 1)
830 * string rngseed (only if OpenSSL is not self-seeded)
833 buffer_put_cstring(&m, buffer_ptr(conf));
835 if (sensitive_data.server_key != NULL &&
836 sensitive_data.server_key->type == KEY_RSA1) {
837 buffer_put_int(&m, 1);
838 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
839 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
840 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
841 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
842 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
843 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
845 buffer_put_int(&m, 0);
847 #ifndef OPENSSL_PRNG_ONLY
848 rexec_send_rng_seed(&m);
851 if (ssh_msg_send(fd, 0, &m) == -1)
852 fatal("%s: ssh_msg_send failed", __func__);
856 debug3("%s: done", __func__);
860 recv_rexec_state(int fd, Buffer *conf)
866 debug3("%s: entering fd = %d", __func__, fd);
870 if (ssh_msg_recv(fd, &m) == -1)
871 fatal("%s: ssh_msg_recv failed", __func__);
872 if (buffer_get_char(&m) != 0)
873 fatal("%s: rexec version mismatch", __func__);
875 cp = buffer_get_string(&m, &len);
877 buffer_append(conf, cp, len + 1);
880 if (buffer_get_int(&m)) {
881 if (sensitive_data.server_key != NULL)
882 key_free(sensitive_data.server_key);
883 sensitive_data.server_key = key_new_private(KEY_RSA1);
884 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
885 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
886 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
887 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
888 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
889 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
890 rsa_generate_additional_parameters(
891 sensitive_data.server_key->rsa);
894 #ifndef OPENSSL_PRNG_ONLY
895 rexec_recv_rng_seed(&m);
900 debug3("%s: done", __func__);
903 /* Accept a connection from inetd */
905 server_accept_inetd(int *sock_in, int *sock_out)
911 close(REEXEC_CONFIG_PASS_FD);
912 *sock_in = *sock_out = dup(STDIN_FILENO);
914 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
915 close(REEXEC_STARTUP_PIPE_FD);
918 *sock_in = dup(STDIN_FILENO);
919 *sock_out = dup(STDOUT_FILENO);
922 * We intentionally do not close the descriptors 0, 1, and 2
923 * as our code for setting the descriptors won't work if
924 * ttyfd happens to be one of those.
926 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
927 dup2(fd, STDIN_FILENO);
928 dup2(fd, STDOUT_FILENO);
929 if (fd > STDOUT_FILENO)
932 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
936 * Listen for TCP connections
941 int ret, listen_sock, on = 1;
943 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
945 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
946 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
948 if (num_listen_socks >= MAX_LISTEN_SOCKS)
949 fatal("Too many listen sockets. "
950 "Enlarge MAX_LISTEN_SOCKS");
951 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
952 ntop, sizeof(ntop), strport, sizeof(strport),
953 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
954 error("getnameinfo failed: %.100s",
955 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
959 /* Create socket for listening. */
960 listen_sock = socket(ai->ai_family, ai->ai_socktype,
962 if (listen_sock < 0) {
963 /* kernel may not support ipv6 */
964 verbose("socket: %.100s", strerror(errno));
967 if (set_nonblock(listen_sock) == -1) {
972 * Set socket options.
973 * Allow local port reuse in TIME_WAIT.
975 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
976 &on, sizeof(on)) == -1)
977 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
979 debug("Bind to port %s on %s.", strport, ntop);
981 /* Bind the socket to the desired port. */
982 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
983 error("Bind to port %s on %s failed: %.200s.",
984 strport, ntop, strerror(errno));
988 listen_socks[num_listen_socks] = listen_sock;
991 /* Start listening on the port. */
992 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
993 fatal("listen on [%s]:%s: %.100s",
994 ntop, strport, strerror(errno));
995 logit("Server listening on %s port %s.", ntop, strport);
997 freeaddrinfo(options.listen_addrs);
999 if (!num_listen_socks)
1000 fatal("Cannot bind any address.");
1004 * The main TCP accept loop. Note that, for the non-debug case, returns
1005 * from this function are in a forked subprocess.
1008 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1011 int i, j, ret, maxfd;
1012 int key_used = 0, startups = 0;
1013 int startup_p[2] = { -1 , -1 };
1014 struct sockaddr_storage from;
1018 /* setup fd set for accept */
1021 for (i = 0; i < num_listen_socks; i++)
1022 if (listen_socks[i] > maxfd)
1023 maxfd = listen_socks[i];
1024 /* pipes connected to unauthenticated childs */
1025 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1026 for (i = 0; i < options.max_startups; i++)
1027 startup_pipes[i] = -1;
1030 * Stay listening for connections until the system crashes or
1031 * the daemon is killed with a signal.
1034 if (received_sighup)
1038 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1041 for (i = 0; i < num_listen_socks; i++)
1042 FD_SET(listen_socks[i], fdset);
1043 for (i = 0; i < options.max_startups; i++)
1044 if (startup_pipes[i] != -1)
1045 FD_SET(startup_pipes[i], fdset);
1047 /* Wait in select until there is a connection. */
1048 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1049 if (ret < 0 && errno != EINTR)
1050 error("select: %.100s", strerror(errno));
1051 if (received_sigterm) {
1052 logit("Received signal %d; terminating.",
1053 (int) received_sigterm);
1054 close_listen_socks();
1055 unlink(options.pid_file);
1058 if (key_used && key_do_regen) {
1059 generate_ephemeral_server_key();
1066 for (i = 0; i < options.max_startups; i++)
1067 if (startup_pipes[i] != -1 &&
1068 FD_ISSET(startup_pipes[i], fdset)) {
1070 * the read end of the pipe is ready
1071 * if the child has closed the pipe
1072 * after successful authentication
1073 * or if the child has died
1075 close(startup_pipes[i]);
1076 startup_pipes[i] = -1;
1079 for (i = 0; i < num_listen_socks; i++) {
1080 if (!FD_ISSET(listen_socks[i], fdset))
1082 fromlen = sizeof(from);
1083 *newsock = accept(listen_socks[i],
1084 (struct sockaddr *)&from, &fromlen);
1086 if (errno != EINTR && errno != EWOULDBLOCK)
1087 error("accept: %.100s", strerror(errno));
1090 if (unset_nonblock(*newsock) == -1) {
1094 if (drop_connection(startups) == 1) {
1095 debug("drop connection #%d", startups);
1099 if (pipe(startup_p) == -1) {
1104 if (rexec_flag && socketpair(AF_UNIX,
1105 SOCK_STREAM, 0, config_s) == -1) {
1106 error("reexec socketpair: %s",
1109 close(startup_p[0]);
1110 close(startup_p[1]);
1114 for (j = 0; j < options.max_startups; j++)
1115 if (startup_pipes[j] == -1) {
1116 startup_pipes[j] = startup_p[0];
1117 if (maxfd < startup_p[0])
1118 maxfd = startup_p[0];
1124 * Got connection. Fork a child to handle it, unless
1125 * we are in debugging mode.
1129 * In debugging mode. Close the listening
1130 * socket, and start processing the
1131 * connection without forking.
1133 debug("Server will not fork when running in debugging mode.");
1134 close_listen_socks();
1135 *sock_in = *newsock;
1136 *sock_out = *newsock;
1137 close(startup_p[0]);
1138 close(startup_p[1]);
1142 send_rexec_state(config_s[0],
1150 * Normal production daemon. Fork, and have
1151 * the child process the connection. The
1152 * parent continues listening.
1154 platform_pre_fork();
1155 if ((pid = fork()) == 0) {
1157 * Child. Close the listening and
1158 * max_startup sockets. Start using
1159 * the accepted socket. Reinitialize
1160 * logging (since our pid has changed).
1161 * We break out of the loop to handle
1164 platform_post_fork_child();
1165 startup_pipe = startup_p[1];
1166 close_startup_pipes();
1167 close_listen_socks();
1168 *sock_in = *newsock;
1169 *sock_out = *newsock;
1170 log_init(__progname,
1172 options.log_facility,
1179 /* Parent. Stay in the loop. */
1180 platform_post_fork_parent(pid);
1182 error("fork: %.100s", strerror(errno));
1184 debug("Forked child %ld.", (long)pid);
1186 close(startup_p[1]);
1189 send_rexec_state(config_s[0], &cfg);
1195 * Mark that the key has been used (it
1196 * was "given" to the child).
1198 if ((options.protocol & SSH_PROTO_1) &&
1200 /* Schedule server key regeneration alarm. */
1201 signal(SIGALRM, key_regeneration_alarm);
1202 alarm(options.key_regeneration_time);
1209 * Ensure that our random state differs
1210 * from that of the child
1215 /* child process check (or debug mode) */
1216 if (num_listen_socks < 0)
1223 * Main program for the daemon.
1226 main(int ac, char **av)
1228 extern char *optarg;
1231 int sock_in = -1, sock_out = -1, newsock = -1;
1232 const char *remote_ip;
1235 int config_s[2] = { -1 , -1 };
1239 #ifdef HAVE_SECUREWARE
1240 (void)set_auth_parameters(ac, av);
1242 __progname = ssh_get_progname(av[0]);
1245 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1248 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1249 for (i = 0; i < ac; i++)
1250 saved_argv[i] = xstrdup(av[i]);
1251 saved_argv[i] = NULL;
1253 #ifndef HAVE_SETPROCTITLE
1254 /* Prepare for later setproctitle emulation */
1255 compat_init_setproctitle(ac, av);
1259 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1260 debug("setgroups(): %.200s", strerror(errno));
1262 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1265 /* Initialize configuration options to their default values. */
1266 initialize_server_options(&options);
1268 /* Parse command-line arguments. */
1269 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
1272 options.address_family = AF_INET;
1275 options.address_family = AF_INET6;
1278 config_file_name = optarg;
1281 if (debug_flag == 0) {
1283 options.log_level = SYSLOG_LEVEL_DEBUG1;
1284 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1285 options.log_level++;
1307 options.log_level = SYSLOG_LEVEL_QUIET;
1310 options.server_key_bits = (int)strtonum(optarg, 256,
1314 options.ports_from_cmdline = 1;
1315 if (options.num_ports >= MAX_PORTS) {
1316 fprintf(stderr, "too many ports.\n");
1319 options.ports[options.num_ports++] = a2port(optarg);
1320 if (options.ports[options.num_ports-1] == 0) {
1321 fprintf(stderr, "Bad port number.\n");
1326 if ((options.login_grace_time = convtime(optarg)) == -1) {
1327 fprintf(stderr, "Invalid login grace time.\n");
1332 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1333 fprintf(stderr, "Invalid key regeneration interval.\n");
1338 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1339 fprintf(stderr, "too many host keys.\n");
1342 options.host_key_files[options.num_host_key_files++] = optarg;
1348 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1349 if (utmp_len > MAXHOSTNAMELEN) {
1350 fprintf(stderr, "Invalid utmp length.\n");
1355 line = xstrdup(optarg);
1356 if (process_server_config_line(&options, line,
1357 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1367 if (rexeced_flag || inetd_flag)
1369 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1370 fatal("sshd re-exec requires execution with an absolute path");
1372 closefrom(REEXEC_MIN_FREE_FD);
1374 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1376 SSLeay_add_all_algorithms();
1379 * Force logging to stderr until we have loaded the private host
1380 * key (unless started from inetd)
1382 log_init(__progname,
1383 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1384 SYSLOG_LEVEL_INFO : options.log_level,
1385 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1386 SYSLOG_FACILITY_AUTH : options.log_facility,
1387 log_stderr || !inetd_flag);
1390 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1391 * root's environment
1393 if (getenv("KRB5CCNAME") != NULL)
1394 unsetenv("KRB5CCNAME");
1397 /* Cray can define user privs drop all privs now!
1398 * Not needed on PRIV_SU systems!
1403 sensitive_data.server_key = NULL;
1404 sensitive_data.ssh1_host_key = NULL;
1405 sensitive_data.have_ssh1_key = 0;
1406 sensitive_data.have_ssh2_key = 0;
1408 /* Fetch our configuration */
1411 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1413 load_server_config(config_file_name, &cfg);
1415 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1416 &cfg, NULL, NULL, NULL);
1420 /* Fill in default values for those options not explicitly set. */
1421 fill_default_server_options(&options);
1423 /* set default channel AF */
1424 channel_set_af(options.address_family);
1426 /* Check that there are no remaining arguments. */
1428 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1432 debug("sshd version %.100s", SSH_RELEASE);
1434 /* Store privilege separation user for later use */
1435 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1436 fatal("Privilege separation user %s does not exist",
1438 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1439 privsep_pw->pw_passwd = "*";
1440 privsep_pw = pwcopy(privsep_pw);
1443 /* load private host keys */
1444 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1446 for (i = 0; i < options.num_host_key_files; i++)
1447 sensitive_data.host_keys[i] = NULL;
1449 for (i = 0; i < options.num_host_key_files; i++) {
1450 key = key_load_private(options.host_key_files[i], "", NULL);
1451 sensitive_data.host_keys[i] = key;
1453 error("Could not load host key: %s",
1454 options.host_key_files[i]);
1455 sensitive_data.host_keys[i] = NULL;
1458 switch (key->type) {
1460 sensitive_data.ssh1_host_key = key;
1461 sensitive_data.have_ssh1_key = 1;
1465 sensitive_data.have_ssh2_key = 1;
1468 debug("private host key: #%d type %d %s", i, key->type,
1471 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1472 logit("Disabling protocol version 1. Could not load host key");
1473 options.protocol &= ~SSH_PROTO_1;
1475 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1476 logit("Disabling protocol version 2. Could not load host key");
1477 options.protocol &= ~SSH_PROTO_2;
1479 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1480 logit("sshd: no hostkeys available -- exiting.");
1484 /* Check certain values for sanity. */
1485 if (options.protocol & SSH_PROTO_1) {
1486 if (options.server_key_bits < 512 ||
1487 options.server_key_bits > 32768) {
1488 fprintf(stderr, "Bad server key size.\n");
1492 * Check that server and host key lengths differ sufficiently. This
1493 * is necessary to make double encryption work with rsaref. Oh, I
1494 * hate software patents. I dont know if this can go? Niels
1496 if (options.server_key_bits >
1497 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1498 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1499 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1500 SSH_KEY_BITS_RESERVED) {
1501 options.server_key_bits =
1502 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1503 SSH_KEY_BITS_RESERVED;
1504 debug("Forcing server key to %d bits to make it differ from host key.",
1505 options.server_key_bits);
1512 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1513 (S_ISDIR(st.st_mode) == 0))
1514 fatal("Missing privilege separation directory: %s",
1515 _PATH_PRIVSEP_CHROOT_DIR);
1518 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1519 (st.st_uid != getuid () ||
1520 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1522 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1524 fatal("%s must be owned by root and not group or "
1525 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1528 /* Configuration looks good, so exit if in test mode. */
1533 * Clear out any supplemental groups we may have inherited. This
1534 * prevents inadvertent creation of files with bad modes (in the
1535 * portable version at least, it's certainly possible for PAM
1536 * to create a file, and we can't control the code in every
1537 * module which might be used).
1539 if (setgroups(0, NULL) < 0)
1540 debug("setgroups() failed: %.200s", strerror(errno));
1543 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1544 for (i = 0; i < rexec_argc; i++) {
1545 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1546 rexec_argv[i] = saved_argv[i];
1548 rexec_argv[rexec_argc] = "-R";
1549 rexec_argv[rexec_argc + 1] = NULL;
1552 /* Initialize the log (it is reinitialized below in case we forked). */
1553 if (debug_flag && (!inetd_flag || rexeced_flag))
1555 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1558 * If not in debugging mode, and not started from inetd, disconnect
1559 * from the controlling terminal, and fork. The original process
1562 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1565 #endif /* TIOCNOTTY */
1566 if (daemon(0, 0) < 0)
1567 fatal("daemon() failed: %.200s", strerror(errno));
1569 /* Disconnect from the controlling tty. */
1571 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1573 (void) ioctl(fd, TIOCNOTTY, NULL);
1576 #endif /* TIOCNOTTY */
1578 /* Reinitialize the log (because of the fork above). */
1579 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1581 /* Initialize the random number generator. */
1584 /* Chdir to the root directory so that the current disk can be
1585 unmounted if desired. */
1588 /* ignore SIGPIPE */
1589 signal(SIGPIPE, SIG_IGN);
1591 /* Get a connection, either from inetd or a listening TCP socket */
1593 server_accept_inetd(&sock_in, &sock_out);
1595 if ((options.protocol & SSH_PROTO_1) &&
1596 sensitive_data.server_key == NULL)
1597 generate_ephemeral_server_key();
1601 if (options.protocol & SSH_PROTO_1)
1602 generate_ephemeral_server_key();
1604 signal(SIGHUP, sighup_handler);
1605 signal(SIGCHLD, main_sigchld_handler);
1606 signal(SIGTERM, sigterm_handler);
1607 signal(SIGQUIT, sigterm_handler);
1610 * Write out the pid file after the sigterm handler
1611 * is setup and the listen sockets are bound
1614 FILE *f = fopen(options.pid_file, "w");
1617 error("Couldn't create pid file \"%s\": %s",
1618 options.pid_file, strerror(errno));
1620 fprintf(f, "%ld\n", (long) getpid());
1625 /* Accept a connection and return in a forked child */
1626 server_accept_loop(&sock_in, &sock_out,
1627 &newsock, config_s);
1630 /* This is the child processing a new connection. */
1631 setproctitle("%s", "[accepted]");
1634 * Create a new session and process group since the 4.4BSD
1635 * setlogin() affects the entire process group. We don't
1636 * want the child to be able to affect the parent.
1638 #if !defined(SSHD_ACQUIRES_CTTY)
1640 * If setsid is called, on some platforms sshd will later acquire a
1641 * controlling terminal which will result in "could not set
1642 * controlling tty" errors.
1644 if (!debug_flag && !inetd_flag && setsid() < 0)
1645 error("setsid: %.100s", strerror(errno));
1651 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1652 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1653 dup2(newsock, STDIN_FILENO);
1654 dup2(STDIN_FILENO, STDOUT_FILENO);
1655 if (startup_pipe == -1)
1656 close(REEXEC_STARTUP_PIPE_FD);
1658 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1660 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1662 if (startup_pipe != -1)
1663 close(startup_pipe);
1665 execv(rexec_argv[0], rexec_argv);
1667 /* Reexec has failed, fall back and continue */
1668 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1669 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1670 log_init(__progname, options.log_level,
1671 options.log_facility, log_stderr);
1674 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1676 close(REEXEC_CONFIG_PASS_FD);
1677 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1678 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1679 dup2(fd, STDIN_FILENO);
1680 dup2(fd, STDOUT_FILENO);
1681 if (fd > STDERR_FILENO)
1684 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1685 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1689 * Disable the key regeneration alarm. We will not regenerate the
1690 * key since we are no longer in a position to give it to anyone. We
1691 * will not restart on SIGHUP since it no longer makes sense.
1694 signal(SIGALRM, SIG_DFL);
1695 signal(SIGHUP, SIG_DFL);
1696 signal(SIGTERM, SIG_DFL);
1697 signal(SIGQUIT, SIG_DFL);
1698 signal(SIGCHLD, SIG_DFL);
1699 signal(SIGINT, SIG_DFL);
1702 * Register our connection. This turns encryption off because we do
1705 packet_set_connection(sock_in, sock_out);
1706 packet_set_server();
1708 /* Set SO_KEEPALIVE if requested. */
1709 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1710 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1711 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1713 if ((remote_port = get_remote_port()) < 0) {
1714 debug("get_remote_port failed");
1719 * We use get_canonical_hostname with usedns = 0 instead of
1720 * get_remote_ipaddr here so IP options will be checked.
1722 (void) get_canonical_hostname(0);
1724 * The rest of the code depends on the fact that
1725 * get_remote_ipaddr() caches the remote ip, even if
1726 * the socket goes away.
1728 remote_ip = get_remote_ipaddr();
1730 #ifdef SSH_AUDIT_EVENTS
1731 audit_connection_from(remote_ip, remote_port);
1734 /* Check whether logins are denied from this host. */
1735 if (packet_connection_is_on_socket()) {
1736 struct request_info req;
1738 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1741 if (!hosts_access(&req)) {
1742 debug("Connection refused by tcp wrapper");
1745 fatal("libwrap refuse returns");
1748 #endif /* LIBWRAP */
1750 /* Log the connection. */
1751 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1754 * We don't want to listen forever unless the other side
1755 * successfully authenticates itself. So we set up an alarm which is
1756 * cleared after successful authentication. A limit of zero
1757 * indicates no limit. Note that we don't set the alarm in debugging
1758 * mode; it is just annoying to have the server exit just when you
1759 * are about to discover the bug.
1761 signal(SIGALRM, grace_alarm_handler);
1763 alarm(options.login_grace_time);
1765 sshd_exchange_identification(sock_in, sock_out);
1767 packet_set_nonblocking();
1769 /* allocate authentication context */
1770 authctxt = xcalloc(1, sizeof(*authctxt));
1772 authctxt->loginmsg = &loginmsg;
1774 /* XXX global for cleanup, access from other modules */
1775 the_authctxt = authctxt;
1777 /* prepare buffer to collect messages to display to user after login */
1778 buffer_init(&loginmsg);
1781 if (privsep_preauth(authctxt) == 1)
1784 /* perform the key exchange */
1785 /* authenticate user and start session */
1788 do_authentication2(authctxt);
1791 do_authentication(authctxt);
1794 * If we use privilege separation, the unprivileged child transfers
1795 * the current keystate and exits
1798 mm_send_keystate(pmonitor);
1804 * Cancel the alarm we set to limit the time taken for
1808 signal(SIGALRM, SIG_DFL);
1809 authctxt->authenticated = 1;
1810 if (startup_pipe != -1) {
1811 close(startup_pipe);
1815 #ifdef SSH_AUDIT_EVENTS
1816 audit_event(SSH_AUTH_SUCCESS);
1820 * In privilege separation, we fork another child and prepare
1821 * file descriptor passing.
1824 privsep_postauth(authctxt);
1825 /* the monitor process [priv] will not return */
1827 destroy_sensitive_data();
1830 /* Start session. */
1831 do_authenticated(authctxt);
1833 /* The connection has been terminated. */
1834 verbose("Closing connection to %.100s", remote_ip);
1837 if (options.use_pam)
1839 #endif /* USE_PAM */
1841 #ifdef SSH_AUDIT_EVENTS
1842 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1854 * Decrypt session_key_int using our private server key and private host key
1855 * (key with larger modulus first).
1858 ssh1_session_key(BIGNUM *session_key_int)
1862 if (BN_cmp(sensitive_data.server_key->rsa->n,
1863 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1864 /* Server key has bigger modulus. */
1865 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1866 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1867 SSH_KEY_BITS_RESERVED) {
1868 fatal("do_connection: %s: "
1869 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1870 get_remote_ipaddr(),
1871 BN_num_bits(sensitive_data.server_key->rsa->n),
1872 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1873 SSH_KEY_BITS_RESERVED);
1875 if (rsa_private_decrypt(session_key_int, session_key_int,
1876 sensitive_data.server_key->rsa) <= 0)
1878 if (rsa_private_decrypt(session_key_int, session_key_int,
1879 sensitive_data.ssh1_host_key->rsa) <= 0)
1882 /* Host key has bigger modulus (or they are equal). */
1883 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1884 BN_num_bits(sensitive_data.server_key->rsa->n) +
1885 SSH_KEY_BITS_RESERVED) {
1886 fatal("do_connection: %s: "
1887 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1888 get_remote_ipaddr(),
1889 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1890 BN_num_bits(sensitive_data.server_key->rsa->n),
1891 SSH_KEY_BITS_RESERVED);
1893 if (rsa_private_decrypt(session_key_int, session_key_int,
1894 sensitive_data.ssh1_host_key->rsa) < 0)
1896 if (rsa_private_decrypt(session_key_int, session_key_int,
1897 sensitive_data.server_key->rsa) < 0)
1910 BIGNUM *session_key_int;
1911 u_char session_key[SSH_SESSION_KEY_LENGTH];
1913 u_int cipher_type, auth_mask, protocol_flags;
1917 * Generate check bytes that the client must send back in the user
1918 * packet in order for it to be accepted; this is used to defy ip
1919 * spoofing attacks. Note that this only works against somebody
1920 * doing IP spoofing from a remote machine; any machine on the local
1921 * network can still see outgoing packets and catch the random
1922 * cookie. This only affects rhosts authentication, and this is one
1923 * of the reasons why it is inherently insecure.
1925 for (i = 0; i < 8; i++) {
1928 cookie[i] = rnd & 0xff;
1933 * Send our public key. We include in the packet 64 bits of random
1934 * data that must be matched in the reply in order to prevent IP
1937 packet_start(SSH_SMSG_PUBLIC_KEY);
1938 for (i = 0; i < 8; i++)
1939 packet_put_char(cookie[i]);
1941 /* Store our public server RSA key. */
1942 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1943 packet_put_bignum(sensitive_data.server_key->rsa->e);
1944 packet_put_bignum(sensitive_data.server_key->rsa->n);
1946 /* Store our public host RSA key. */
1947 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1948 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1949 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1951 /* Put protocol flags. */
1952 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1954 /* Declare which ciphers we support. */
1955 packet_put_int(cipher_mask_ssh1(0));
1957 /* Declare supported authentication types. */
1959 if (options.rhosts_rsa_authentication)
1960 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1961 if (options.rsa_authentication)
1962 auth_mask |= 1 << SSH_AUTH_RSA;
1963 if (options.challenge_response_authentication == 1)
1964 auth_mask |= 1 << SSH_AUTH_TIS;
1965 if (options.password_authentication)
1966 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1967 packet_put_int(auth_mask);
1969 /* Send the packet and wait for it to be sent. */
1971 packet_write_wait();
1973 debug("Sent %d bit server key and %d bit host key.",
1974 BN_num_bits(sensitive_data.server_key->rsa->n),
1975 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1977 /* Read clients reply (cipher type and session key). */
1978 packet_read_expect(SSH_CMSG_SESSION_KEY);
1980 /* Get cipher type and check whether we accept this. */
1981 cipher_type = packet_get_char();
1983 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1984 packet_disconnect("Warning: client selects unsupported cipher.");
1986 /* Get check bytes from the packet. These must match those we
1987 sent earlier with the public key packet. */
1988 for (i = 0; i < 8; i++)
1989 if (cookie[i] != packet_get_char())
1990 packet_disconnect("IP Spoofing check bytes do not match.");
1992 debug("Encryption type: %.200s", cipher_name(cipher_type));
1994 /* Get the encrypted integer. */
1995 if ((session_key_int = BN_new()) == NULL)
1996 fatal("do_ssh1_kex: BN_new failed");
1997 packet_get_bignum(session_key_int);
1999 protocol_flags = packet_get_int();
2000 packet_set_protocol_flags(protocol_flags);
2003 /* Decrypt session_key_int using host/server keys */
2004 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2007 * Extract session key from the decrypted integer. The key is in the
2008 * least significant 256 bits of the integer; the first byte of the
2009 * key is in the highest bits.
2012 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2013 len = BN_num_bytes(session_key_int);
2014 if (len < 0 || (u_int)len > sizeof(session_key)) {
2015 error("do_connection: bad session key len from %s: "
2016 "session_key_int %d > sizeof(session_key) %lu",
2017 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2020 memset(session_key, 0, sizeof(session_key));
2021 BN_bn2bin(session_key_int,
2022 session_key + sizeof(session_key) - len);
2024 derive_ssh1_session_id(
2025 sensitive_data.ssh1_host_key->rsa->n,
2026 sensitive_data.server_key->rsa->n,
2027 cookie, session_id);
2029 * Xor the first 16 bytes of the session key with the
2032 for (i = 0; i < 16; i++)
2033 session_key[i] ^= session_id[i];
2037 int bytes = BN_num_bytes(session_key_int);
2038 u_char *buf = xmalloc(bytes);
2041 logit("do_connection: generating a fake encryption key");
2042 BN_bn2bin(session_key_int, buf);
2044 MD5_Update(&md, buf, bytes);
2045 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2046 MD5_Final(session_key, &md);
2048 MD5_Update(&md, session_key, 16);
2049 MD5_Update(&md, buf, bytes);
2050 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2051 MD5_Final(session_key + 16, &md);
2052 memset(buf, 0, bytes);
2054 for (i = 0; i < 16; i++)
2055 session_id[i] = session_key[i] ^ session_key[i + 16];
2057 /* Destroy the private and public keys. No longer. */
2058 destroy_sensitive_data();
2061 mm_ssh1_session_id(session_id);
2063 /* Destroy the decrypted integer. It is no longer needed. */
2064 BN_clear_free(session_key_int);
2066 /* Set the session key. From this on all communications will be encrypted. */
2067 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2069 /* Destroy our copy of the session key. It is no longer needed. */
2070 memset(session_key, 0, sizeof(session_key));
2072 debug("Received session key; encryption turned on.");
2074 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2075 packet_start(SSH_SMSG_SUCCESS);
2077 packet_write_wait();
2081 * SSH2 key exchange: diffie-hellman-group1-sha1
2088 if (options.ciphers != NULL) {
2089 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2090 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2092 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2093 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2094 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2095 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2097 if (options.macs != NULL) {
2098 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2099 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2101 if (options.compression == COMP_NONE) {
2102 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2103 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2104 } else if (options.compression == COMP_DELAYED) {
2105 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2106 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2109 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2111 /* start key exchange */
2112 kex = kex_setup(myproposal);
2113 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2114 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2115 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2116 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2118 kex->client_version_string=client_version_string;
2119 kex->server_version_string=server_version_string;
2120 kex->load_host_key=&get_hostkey_by_type;
2121 kex->host_key_index=&get_hostkey_index;
2125 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2127 session_id2 = kex->session_id;
2128 session_id2_len = kex->session_id_len;
2131 /* send 1st encrypted/maced/compressed message */
2132 packet_start(SSH2_MSG_IGNORE);
2133 packet_put_cstring("markus");
2135 packet_write_wait();
2140 /* server specific fatal cleanup */
2145 do_cleanup(the_authctxt);
2146 #ifdef SSH_AUDIT_EVENTS
2147 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2148 if (!use_privsep || mm_is_monitor())
2149 audit_event(SSH_CONNECTION_ABANDON);