1 /* $OpenBSD: sshd.c,v 1.356 2008/04/13 00:22:17 djm 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 #include "openbsd-compat/openssl-compat.h"
80 #ifdef HAVE_SECUREWARE
81 #include <sys/security.h>
101 #include "myproposal.h"
102 #include "authfile.h"
103 #include "pathnames.h"
104 #include "atomicio.h"
105 #include "canohost.h"
106 #include "hostfile.h"
110 #include "dispatch.h"
111 #include "channels.h"
113 #include "monitor_mm.h"
118 #include "monitor_wrap.h"
119 #include "monitor_fdpass.h"
134 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
135 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
136 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
137 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
139 extern char *__progname;
141 /* Server configuration options. */
142 ServerOptions options;
144 /* Name of the server configuration file. */
145 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
148 * Debug mode flag. This can be set on the command line. If debug
149 * mode is enabled, extra debugging output will be sent to the system
150 * log, the daemon will not go to background, and will exit after processing
151 * the first connection.
155 /* Flag indicating that the daemon should only test the configuration and keys. */
158 /* Flag indicating that the daemon is being started from inetd. */
161 /* Flag indicating that sshd should not detach and become a daemon. */
162 int no_daemon_flag = 0;
164 /* debug goes to stderr unless inetd_flag is set */
167 /* Saved arguments to main(). */
172 int rexeced_flag = 0;
178 * The sockets that the server is listening; this is used in the SIGHUP
181 #define MAX_LISTEN_SOCKS 16
182 int listen_socks[MAX_LISTEN_SOCKS];
183 int num_listen_socks = 0;
186 * the client's version string, passed by sshd2 in compat mode. if != NULL,
187 * sshd will skip the version-number exchange
189 char *client_version_string = NULL;
190 char *server_version_string = NULL;
192 /* for rekeying XXX fixme */
196 * Any really sensitive data in the application is contained in this
197 * structure. The idea is that this structure could be locked into memory so
198 * that the pages do not get written into swap. However, there are some
199 * problems. The private key contains BIGNUMs, and we do not (in principle)
200 * have access to the internals of them, and locking just the structure is
201 * not very useful. Currently, memory locking is not implemented.
204 Key *server_key; /* ephemeral server key */
205 Key *ssh1_host_key; /* ssh1 host key */
206 Key **host_keys; /* all private host keys */
209 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
213 * Flag indicating whether the RSA server key needs to be regenerated.
214 * Is set in the SIGALRM handler and cleared when the key is regenerated.
216 static volatile sig_atomic_t key_do_regen = 0;
218 /* This is set to true when a signal is received. */
219 static volatile sig_atomic_t received_sighup = 0;
220 static volatile sig_atomic_t received_sigterm = 0;
222 /* session identifier, used by RSA-auth */
223 u_char session_id[16];
226 u_char *session_id2 = NULL;
227 u_int session_id2_len = 0;
229 /* record remote hostname or ip */
230 u_int utmp_len = MAXHOSTNAMELEN;
232 /* options.max_startup sized array of fd ints */
233 int *startup_pipes = NULL;
234 int startup_pipe; /* in child */
236 /* variables used for privilege separation */
237 int use_privsep = -1;
238 struct monitor *pmonitor = NULL;
240 /* global authentication context */
241 Authctxt *the_authctxt = NULL;
243 /* sshd_config buffer */
246 /* message to be displayed after login */
249 /* Unprivileged user */
250 struct passwd *privsep_pw = NULL;
252 /* Prototypes for various functions defined later in this file. */
253 void destroy_sensitive_data(void);
254 void demote_sensitive_data(void);
256 static void do_ssh1_kex(void);
257 static void do_ssh2_kex(void);
260 * Close all listening sockets
263 close_listen_socks(void)
267 for (i = 0; i < num_listen_socks; i++)
268 close(listen_socks[i]);
269 num_listen_socks = -1;
273 close_startup_pipes(void)
278 for (i = 0; i < options.max_startups; i++)
279 if (startup_pipes[i] != -1)
280 close(startup_pipes[i]);
284 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
285 * the effect is to reread the configuration file (and to regenerate
291 sighup_handler(int sig)
293 int save_errno = errno;
296 signal(SIGHUP, sighup_handler);
301 * Called from the main program after receiving SIGHUP.
302 * Restarts the server.
307 logit("Received SIGHUP; restarting.");
308 close_listen_socks();
309 close_startup_pipes();
310 alarm(0); /* alarm timer persists across exec */
311 execv(saved_argv[0], saved_argv);
312 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
318 * Generic signal handler for terminating signals in the master daemon.
322 sigterm_handler(int sig)
324 received_sigterm = sig;
328 * SIGCHLD handler. This is called whenever a child dies. This will then
329 * reap any zombies left by exited children.
333 main_sigchld_handler(int sig)
335 int save_errno = errno;
339 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
340 (pid < 0 && errno == EINTR))
343 signal(SIGCHLD, main_sigchld_handler);
348 * Signal handler for the alarm after the login grace period has expired.
352 grace_alarm_handler(int sig)
354 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
355 kill(pmonitor->m_pid, SIGALRM);
357 /* Log error and exit. */
358 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
362 * Signal handler for the key regeneration alarm. Note that this
363 * alarm only occurs in the daemon waiting for connections, and it does not
364 * do anything with the private key or random state before forking.
365 * Thus there should be no concurrency control/asynchronous execution
369 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 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
385 key_regeneration_alarm(int sig)
387 int save_errno = errno;
389 signal(SIGALRM, SIG_DFL);
395 sshd_exchange_identification(int sock_in, int sock_out)
399 int remote_major, remote_minor;
402 char buf[256]; /* Must not be larger than remote_version. */
403 char remote_version[256]; /* Must be at least as big as buf. */
405 if ((options.protocol & SSH_PROTO_1) &&
406 (options.protocol & SSH_PROTO_2)) {
407 major = PROTOCOL_MAJOR_1;
409 } else if (options.protocol & SSH_PROTO_2) {
410 major = PROTOCOL_MAJOR_2;
411 minor = PROTOCOL_MINOR_2;
413 major = PROTOCOL_MAJOR_1;
414 minor = PROTOCOL_MINOR_1;
416 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
417 server_version_string = xstrdup(buf);
419 /* Send our protocol version identification. */
420 if (atomicio(vwrite, sock_out, server_version_string,
421 strlen(server_version_string))
422 != strlen(server_version_string)) {
423 logit("Could not write ident string to %s", get_remote_ipaddr());
427 /* Read other sides version identification. */
428 memset(buf, 0, sizeof(buf));
429 for (i = 0; i < sizeof(buf) - 1; i++) {
430 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
431 logit("Did not receive identification string from %s",
432 get_remote_ipaddr());
435 if (buf[i] == '\r') {
437 /* Kludge for F-Secure Macintosh < 1.0.2 */
439 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
443 if (buf[i] == '\n') {
448 buf[sizeof(buf) - 1] = 0;
449 client_version_string = xstrdup(buf);
452 * Check that the versions match. In future this might accept
453 * several versions and set appropriate flags to handle them.
455 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
456 &remote_major, &remote_minor, remote_version) != 3) {
457 s = "Protocol mismatch.\n";
458 (void) atomicio(vwrite, sock_out, s, strlen(s));
461 logit("Bad protocol version identification '%.100s' from %s",
462 client_version_string, get_remote_ipaddr());
465 debug("Client protocol version %d.%d; client software version %.100s",
466 remote_major, remote_minor, remote_version);
468 compat_datafellows(remote_version);
470 if (datafellows & SSH_BUG_PROBE) {
471 logit("probed from %s with %s. Don't panic.",
472 get_remote_ipaddr(), client_version_string);
476 if (datafellows & SSH_BUG_SCANNER) {
477 logit("scanned from %s with %s. Don't panic.",
478 get_remote_ipaddr(), client_version_string);
483 switch (remote_major) {
485 if (remote_minor == 99) {
486 if (options.protocol & SSH_PROTO_2)
492 if (!(options.protocol & SSH_PROTO_1)) {
496 if (remote_minor < 3) {
497 packet_disconnect("Your ssh version is too old and "
498 "is no longer supported. Please install a newer version.");
499 } else if (remote_minor == 3) {
500 /* note that this disables agent-forwarding */
505 if (options.protocol & SSH_PROTO_2) {
514 chop(server_version_string);
515 debug("Local version string %.200s", server_version_string);
518 s = "Protocol major versions differ.\n";
519 (void) atomicio(vwrite, sock_out, s, strlen(s));
522 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
524 server_version_string, client_version_string);
529 /* Destroy the host and server keys. They will no longer be needed. */
531 destroy_sensitive_data(void)
535 if (sensitive_data.server_key) {
536 key_free(sensitive_data.server_key);
537 sensitive_data.server_key = NULL;
539 for (i = 0; i < options.num_host_key_files; i++) {
540 if (sensitive_data.host_keys[i]) {
541 key_free(sensitive_data.host_keys[i]);
542 sensitive_data.host_keys[i] = NULL;
545 sensitive_data.ssh1_host_key = NULL;
546 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
549 /* Demote private to public keys for network child */
551 demote_sensitive_data(void)
556 if (sensitive_data.server_key) {
557 tmp = key_demote(sensitive_data.server_key);
558 key_free(sensitive_data.server_key);
559 sensitive_data.server_key = tmp;
562 for (i = 0; i < options.num_host_key_files; i++) {
563 if (sensitive_data.host_keys[i]) {
564 tmp = key_demote(sensitive_data.host_keys[i]);
565 key_free(sensitive_data.host_keys[i]);
566 sensitive_data.host_keys[i] = tmp;
567 if (tmp->type == KEY_RSA1)
568 sensitive_data.ssh1_host_key = tmp;
572 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
576 privsep_preauth_child(void)
581 /* Enable challenge-response authentication for privilege separation */
582 privsep_challenge_enable();
585 arc4random_buf(rnd, sizeof(rnd));
586 RAND_seed(rnd, sizeof(rnd));
588 /* Demote the private keys to public keys. */
589 demote_sensitive_data();
591 /* Change our root directory */
592 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
593 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
595 if (chdir("/") == -1)
596 fatal("chdir(\"/\"): %s", strerror(errno));
598 /* Drop our privileges */
599 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
600 (u_int)privsep_pw->pw_gid);
602 /* XXX not ready, too heavy after chroot */
603 do_setusercontext(privsep_pw);
605 gidset[0] = privsep_pw->pw_gid;
606 if (setgroups(1, gidset) < 0)
607 fatal("setgroups: %.100s", strerror(errno));
608 permanently_set_uid(privsep_pw);
613 privsep_preauth(Authctxt *authctxt)
618 /* Set up unprivileged child process to deal with network data */
619 pmonitor = monitor_init();
620 /* Store a pointer to the kex for later rekeying */
621 pmonitor->m_pkex = &xxx_kex;
625 fatal("fork of unprivileged child failed");
626 } else if (pid != 0) {
627 debug2("Network child is on pid %ld", (long)pid);
629 close(pmonitor->m_recvfd);
630 pmonitor->m_pid = pid;
631 monitor_child_preauth(authctxt, pmonitor);
632 close(pmonitor->m_sendfd);
635 monitor_sync(pmonitor);
637 /* Wait for the child's exit status */
638 while (waitpid(pid, &status, 0) < 0)
645 close(pmonitor->m_sendfd);
647 /* Demote the child */
648 if (getuid() == 0 || geteuid() == 0)
649 privsep_preauth_child();
650 setproctitle("%s", "[net]");
656 privsep_postauth(Authctxt *authctxt)
660 #ifdef DISABLE_FD_PASSING
663 if (authctxt->pw->pw_uid == 0 || options.use_login) {
665 /* File descriptor passing is broken or root login */
670 /* New socket pair */
671 monitor_reinit(pmonitor);
673 pmonitor->m_pid = fork();
674 if (pmonitor->m_pid == -1)
675 fatal("fork of unprivileged child failed");
676 else if (pmonitor->m_pid != 0) {
677 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
678 close(pmonitor->m_recvfd);
679 buffer_clear(&loginmsg);
680 monitor_child_postauth(pmonitor);
686 close(pmonitor->m_sendfd);
688 /* Demote the private keys to public keys. */
689 demote_sensitive_data();
692 arc4random_buf(rnd, sizeof(rnd));
693 RAND_seed(rnd, sizeof(rnd));
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_uniform(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 ssh_gai_strerror(ret));
958 /* Create socket for listening. */
959 listen_sock = socket(ai->ai_family, ai->ai_socktype,
961 if (listen_sock < 0) {
962 /* kernel may not support ipv6 */
963 verbose("socket: %.100s", strerror(errno));
966 if (set_nonblock(listen_sock) == -1) {
971 * Set socket options.
972 * Allow local port reuse in TIME_WAIT.
974 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
975 &on, sizeof(on)) == -1)
976 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
979 /* Only communicate in IPv6 over AF_INET6 sockets. */
980 if (ai->ai_family == AF_INET6) {
981 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY,
982 &on, sizeof(on)) == -1)
983 error("setsockopt IPV6_V6ONLY: %s",
988 debug("Bind to port %s on %s.", strport, ntop);
990 /* Bind the socket to the desired port. */
991 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
992 error("Bind to port %s on %s failed: %.200s.",
993 strport, ntop, strerror(errno));
997 listen_socks[num_listen_socks] = listen_sock;
1000 /* Start listening on the port. */
1001 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1002 fatal("listen on [%s]:%s: %.100s",
1003 ntop, strport, strerror(errno));
1004 logit("Server listening on %s port %s.", ntop, strport);
1006 freeaddrinfo(options.listen_addrs);
1008 if (!num_listen_socks)
1009 fatal("Cannot bind any address.");
1013 * The main TCP accept loop. Note that, for the non-debug case, returns
1014 * from this function are in a forked subprocess.
1017 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1020 int i, j, ret, maxfd;
1021 int key_used = 0, startups = 0;
1022 int startup_p[2] = { -1 , -1 };
1023 struct sockaddr_storage from;
1027 /* setup fd set for accept */
1030 for (i = 0; i < num_listen_socks; i++)
1031 if (listen_socks[i] > maxfd)
1032 maxfd = listen_socks[i];
1033 /* pipes connected to unauthenticated childs */
1034 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1035 for (i = 0; i < options.max_startups; i++)
1036 startup_pipes[i] = -1;
1039 * Stay listening for connections until the system crashes or
1040 * the daemon is killed with a signal.
1043 if (received_sighup)
1047 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1050 for (i = 0; i < num_listen_socks; i++)
1051 FD_SET(listen_socks[i], fdset);
1052 for (i = 0; i < options.max_startups; i++)
1053 if (startup_pipes[i] != -1)
1054 FD_SET(startup_pipes[i], fdset);
1056 /* Wait in select until there is a connection. */
1057 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1058 if (ret < 0 && errno != EINTR)
1059 error("select: %.100s", strerror(errno));
1060 if (received_sigterm) {
1061 logit("Received signal %d; terminating.",
1062 (int) received_sigterm);
1063 close_listen_socks();
1064 unlink(options.pid_file);
1067 if (key_used && key_do_regen) {
1068 generate_ephemeral_server_key();
1075 for (i = 0; i < options.max_startups; i++)
1076 if (startup_pipes[i] != -1 &&
1077 FD_ISSET(startup_pipes[i], fdset)) {
1079 * the read end of the pipe is ready
1080 * if the child has closed the pipe
1081 * after successful authentication
1082 * or if the child has died
1084 close(startup_pipes[i]);
1085 startup_pipes[i] = -1;
1088 for (i = 0; i < num_listen_socks; i++) {
1089 if (!FD_ISSET(listen_socks[i], fdset))
1091 fromlen = sizeof(from);
1092 *newsock = accept(listen_socks[i],
1093 (struct sockaddr *)&from, &fromlen);
1095 if (errno != EINTR && errno != EWOULDBLOCK)
1096 error("accept: %.100s", strerror(errno));
1099 if (unset_nonblock(*newsock) == -1) {
1103 if (drop_connection(startups) == 1) {
1104 debug("drop connection #%d", startups);
1108 if (pipe(startup_p) == -1) {
1113 if (rexec_flag && socketpair(AF_UNIX,
1114 SOCK_STREAM, 0, config_s) == -1) {
1115 error("reexec socketpair: %s",
1118 close(startup_p[0]);
1119 close(startup_p[1]);
1123 for (j = 0; j < options.max_startups; j++)
1124 if (startup_pipes[j] == -1) {
1125 startup_pipes[j] = startup_p[0];
1126 if (maxfd < startup_p[0])
1127 maxfd = startup_p[0];
1133 * Got connection. Fork a child to handle it, unless
1134 * we are in debugging mode.
1138 * In debugging mode. Close the listening
1139 * socket, and start processing the
1140 * connection without forking.
1142 debug("Server will not fork when running in debugging mode.");
1143 close_listen_socks();
1144 *sock_in = *newsock;
1145 *sock_out = *newsock;
1146 close(startup_p[0]);
1147 close(startup_p[1]);
1151 send_rexec_state(config_s[0],
1159 * Normal production daemon. Fork, and have
1160 * the child process the connection. The
1161 * parent continues listening.
1163 platform_pre_fork();
1164 if ((pid = fork()) == 0) {
1166 * Child. Close the listening and
1167 * max_startup sockets. Start using
1168 * the accepted socket. Reinitialize
1169 * logging (since our pid has changed).
1170 * We break out of the loop to handle
1173 platform_post_fork_child();
1174 startup_pipe = startup_p[1];
1175 close_startup_pipes();
1176 close_listen_socks();
1177 *sock_in = *newsock;
1178 *sock_out = *newsock;
1179 log_init(__progname,
1181 options.log_facility,
1188 /* Parent. Stay in the loop. */
1189 platform_post_fork_parent(pid);
1191 error("fork: %.100s", strerror(errno));
1193 debug("Forked child %ld.", (long)pid);
1195 close(startup_p[1]);
1198 send_rexec_state(config_s[0], &cfg);
1204 * Mark that the key has been used (it
1205 * was "given" to the child).
1207 if ((options.protocol & SSH_PROTO_1) &&
1209 /* Schedule server key regeneration alarm. */
1210 signal(SIGALRM, key_regeneration_alarm);
1211 alarm(options.key_regeneration_time);
1218 * Ensure that our random state differs
1219 * from that of the child
1224 /* child process check (or debug mode) */
1225 if (num_listen_socks < 0)
1232 * Main program for the daemon.
1235 main(int ac, char **av)
1237 extern char *optarg;
1240 int sock_in = -1, sock_out = -1, newsock = -1;
1241 const char *remote_ip;
1244 int config_s[2] = { -1 , -1 };
1248 #ifdef HAVE_SECUREWARE
1249 (void)set_auth_parameters(ac, av);
1251 __progname = ssh_get_progname(av[0]);
1254 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1257 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1258 for (i = 0; i < ac; i++)
1259 saved_argv[i] = xstrdup(av[i]);
1260 saved_argv[i] = NULL;
1262 #ifndef HAVE_SETPROCTITLE
1263 /* Prepare for later setproctitle emulation */
1264 compat_init_setproctitle(ac, av);
1268 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1269 debug("setgroups(): %.200s", strerror(errno));
1271 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1274 /* Initialize configuration options to their default values. */
1275 initialize_server_options(&options);
1277 /* Parse command-line arguments. */
1278 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
1281 options.address_family = AF_INET;
1284 options.address_family = AF_INET6;
1287 config_file_name = optarg;
1290 if (debug_flag == 0) {
1292 options.log_level = SYSLOG_LEVEL_DEBUG1;
1293 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1294 options.log_level++;
1316 options.log_level = SYSLOG_LEVEL_QUIET;
1319 options.server_key_bits = (int)strtonum(optarg, 256,
1323 options.ports_from_cmdline = 1;
1324 if (options.num_ports >= MAX_PORTS) {
1325 fprintf(stderr, "too many ports.\n");
1328 options.ports[options.num_ports++] = a2port(optarg);
1329 if (options.ports[options.num_ports-1] == 0) {
1330 fprintf(stderr, "Bad port number.\n");
1335 if ((options.login_grace_time = convtime(optarg)) == -1) {
1336 fprintf(stderr, "Invalid login grace time.\n");
1341 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1342 fprintf(stderr, "Invalid key regeneration interval.\n");
1347 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1348 fprintf(stderr, "too many host keys.\n");
1351 options.host_key_files[options.num_host_key_files++] = optarg;
1357 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1358 if (utmp_len > MAXHOSTNAMELEN) {
1359 fprintf(stderr, "Invalid utmp length.\n");
1364 line = xstrdup(optarg);
1365 if (process_server_config_line(&options, line,
1366 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1376 if (rexeced_flag || inetd_flag)
1378 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1379 fatal("sshd re-exec requires execution with an absolute path");
1381 closefrom(REEXEC_MIN_FREE_FD);
1383 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1385 SSLeay_add_all_algorithms();
1388 * Force logging to stderr until we have loaded the private host
1389 * key (unless started from inetd)
1391 log_init(__progname,
1392 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1393 SYSLOG_LEVEL_INFO : options.log_level,
1394 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1395 SYSLOG_FACILITY_AUTH : options.log_facility,
1396 log_stderr || !inetd_flag);
1399 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1400 * root's environment
1402 if (getenv("KRB5CCNAME") != NULL)
1403 unsetenv("KRB5CCNAME");
1406 /* Cray can define user privs drop all privs now!
1407 * Not needed on PRIV_SU systems!
1412 sensitive_data.server_key = NULL;
1413 sensitive_data.ssh1_host_key = NULL;
1414 sensitive_data.have_ssh1_key = 0;
1415 sensitive_data.have_ssh2_key = 0;
1417 /* Fetch our configuration */
1420 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1422 load_server_config(config_file_name, &cfg);
1424 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1425 &cfg, NULL, NULL, NULL);
1429 /* Fill in default values for those options not explicitly set. */
1430 fill_default_server_options(&options);
1432 /* challenge-response is implemented via keyboard interactive */
1433 if (options.challenge_response_authentication)
1434 options.kbd_interactive_authentication = 1;
1436 /* set default channel AF */
1437 channel_set_af(options.address_family);
1439 /* Check that there are no remaining arguments. */
1441 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1445 debug("sshd version %.100s", SSH_RELEASE);
1447 /* Store privilege separation user for later use if required. */
1448 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1449 if (use_privsep || options.kerberos_authentication)
1450 fatal("Privilege separation user %s does not exist",
1453 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1454 privsep_pw = pwcopy(privsep_pw);
1455 xfree(privsep_pw->pw_passwd);
1456 privsep_pw->pw_passwd = xstrdup("*");
1460 /* load private host keys */
1461 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1463 for (i = 0; i < options.num_host_key_files; i++)
1464 sensitive_data.host_keys[i] = NULL;
1466 for (i = 0; i < options.num_host_key_files; i++) {
1467 key = key_load_private(options.host_key_files[i], "", NULL);
1468 sensitive_data.host_keys[i] = key;
1470 error("Could not load host key: %s",
1471 options.host_key_files[i]);
1472 sensitive_data.host_keys[i] = NULL;
1475 switch (key->type) {
1477 sensitive_data.ssh1_host_key = key;
1478 sensitive_data.have_ssh1_key = 1;
1482 sensitive_data.have_ssh2_key = 1;
1485 debug("private host key: #%d type %d %s", i, key->type,
1488 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1489 logit("Disabling protocol version 1. Could not load host key");
1490 options.protocol &= ~SSH_PROTO_1;
1492 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1493 logit("Disabling protocol version 2. Could not load host key");
1494 options.protocol &= ~SSH_PROTO_2;
1496 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1497 logit("sshd: no hostkeys available -- exiting.");
1501 /* Check certain values for sanity. */
1502 if (options.protocol & SSH_PROTO_1) {
1503 if (options.server_key_bits < 512 ||
1504 options.server_key_bits > 32768) {
1505 fprintf(stderr, "Bad server key size.\n");
1509 * Check that server and host key lengths differ sufficiently. This
1510 * is necessary to make double encryption work with rsaref. Oh, I
1511 * hate software patents. I dont know if this can go? Niels
1513 if (options.server_key_bits >
1514 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1515 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1516 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1517 SSH_KEY_BITS_RESERVED) {
1518 options.server_key_bits =
1519 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1520 SSH_KEY_BITS_RESERVED;
1521 debug("Forcing server key to %d bits to make it differ from host key.",
1522 options.server_key_bits);
1529 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1530 (S_ISDIR(st.st_mode) == 0))
1531 fatal("Missing privilege separation directory: %s",
1532 _PATH_PRIVSEP_CHROOT_DIR);
1535 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1536 (st.st_uid != getuid () ||
1537 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1539 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1541 fatal("%s must be owned by root and not group or "
1542 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1545 /* Configuration looks good, so exit if in test mode. */
1550 * Clear out any supplemental groups we may have inherited. This
1551 * prevents inadvertent creation of files with bad modes (in the
1552 * portable version at least, it's certainly possible for PAM
1553 * to create a file, and we can't control the code in every
1554 * module which might be used).
1556 if (setgroups(0, NULL) < 0)
1557 debug("setgroups() failed: %.200s", strerror(errno));
1560 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1561 for (i = 0; i < rexec_argc; i++) {
1562 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1563 rexec_argv[i] = saved_argv[i];
1565 rexec_argv[rexec_argc] = "-R";
1566 rexec_argv[rexec_argc + 1] = NULL;
1569 /* Initialize the log (it is reinitialized below in case we forked). */
1570 if (debug_flag && (!inetd_flag || rexeced_flag))
1572 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1575 * If not in debugging mode, and not started from inetd, disconnect
1576 * from the controlling terminal, and fork. The original process
1579 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1582 #endif /* TIOCNOTTY */
1583 if (daemon(0, 0) < 0)
1584 fatal("daemon() failed: %.200s", strerror(errno));
1586 /* Disconnect from the controlling tty. */
1588 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1590 (void) ioctl(fd, TIOCNOTTY, NULL);
1593 #endif /* TIOCNOTTY */
1595 /* Reinitialize the log (because of the fork above). */
1596 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1598 /* Initialize the random number generator. */
1601 /* Chdir to the root directory so that the current disk can be
1602 unmounted if desired. */
1605 /* ignore SIGPIPE */
1606 signal(SIGPIPE, SIG_IGN);
1608 /* Get a connection, either from inetd or a listening TCP socket */
1610 server_accept_inetd(&sock_in, &sock_out);
1614 if (options.protocol & SSH_PROTO_1)
1615 generate_ephemeral_server_key();
1617 signal(SIGHUP, sighup_handler);
1618 signal(SIGCHLD, main_sigchld_handler);
1619 signal(SIGTERM, sigterm_handler);
1620 signal(SIGQUIT, sigterm_handler);
1623 * Write out the pid file after the sigterm handler
1624 * is setup and the listen sockets are bound
1627 FILE *f = fopen(options.pid_file, "w");
1630 error("Couldn't create pid file \"%s\": %s",
1631 options.pid_file, strerror(errno));
1633 fprintf(f, "%ld\n", (long) getpid());
1638 /* Accept a connection and return in a forked child */
1639 server_accept_loop(&sock_in, &sock_out,
1640 &newsock, config_s);
1643 /* This is the child processing a new connection. */
1644 setproctitle("%s", "[accepted]");
1647 * Create a new session and process group since the 4.4BSD
1648 * setlogin() affects the entire process group. We don't
1649 * want the child to be able to affect the parent.
1651 #if !defined(SSHD_ACQUIRES_CTTY)
1653 * If setsid is called, on some platforms sshd will later acquire a
1654 * controlling terminal which will result in "could not set
1655 * controlling tty" errors.
1657 if (!debug_flag && !inetd_flag && setsid() < 0)
1658 error("setsid: %.100s", strerror(errno));
1664 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1665 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1666 dup2(newsock, STDIN_FILENO);
1667 dup2(STDIN_FILENO, STDOUT_FILENO);
1668 if (startup_pipe == -1)
1669 close(REEXEC_STARTUP_PIPE_FD);
1671 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1673 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1675 if (startup_pipe != -1)
1676 close(startup_pipe);
1678 execv(rexec_argv[0], rexec_argv);
1680 /* Reexec has failed, fall back and continue */
1681 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1682 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1683 log_init(__progname, options.log_level,
1684 options.log_facility, log_stderr);
1687 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1689 close(REEXEC_CONFIG_PASS_FD);
1690 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1691 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1692 dup2(fd, STDIN_FILENO);
1693 dup2(fd, STDOUT_FILENO);
1694 if (fd > STDERR_FILENO)
1697 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1698 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1702 * Disable the key regeneration alarm. We will not regenerate the
1703 * key since we are no longer in a position to give it to anyone. We
1704 * will not restart on SIGHUP since it no longer makes sense.
1707 signal(SIGALRM, SIG_DFL);
1708 signal(SIGHUP, SIG_DFL);
1709 signal(SIGTERM, SIG_DFL);
1710 signal(SIGQUIT, SIG_DFL);
1711 signal(SIGCHLD, SIG_DFL);
1712 signal(SIGINT, SIG_DFL);
1715 * Register our connection. This turns encryption off because we do
1718 packet_set_connection(sock_in, sock_out);
1719 packet_set_server();
1721 /* Set SO_KEEPALIVE if requested. */
1722 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1723 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1724 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1726 if ((remote_port = get_remote_port()) < 0) {
1727 debug("get_remote_port failed");
1732 * We use get_canonical_hostname with usedns = 0 instead of
1733 * get_remote_ipaddr here so IP options will be checked.
1735 (void) get_canonical_hostname(0);
1737 * The rest of the code depends on the fact that
1738 * get_remote_ipaddr() caches the remote ip, even if
1739 * the socket goes away.
1741 remote_ip = get_remote_ipaddr();
1743 #ifdef SSH_AUDIT_EVENTS
1744 audit_connection_from(remote_ip, remote_port);
1747 allow_severity = options.log_facility|LOG_INFO;
1748 deny_severity = options.log_facility|LOG_WARNING;
1749 /* Check whether logins are denied from this host. */
1750 if (packet_connection_is_on_socket()) {
1751 struct request_info req;
1753 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1756 if (!hosts_access(&req)) {
1757 debug("Connection refused by tcp wrapper");
1760 fatal("libwrap refuse returns");
1763 #endif /* LIBWRAP */
1765 /* Log the connection. */
1766 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1769 * We don't want to listen forever unless the other side
1770 * successfully authenticates itself. So we set up an alarm which is
1771 * cleared after successful authentication. A limit of zero
1772 * indicates no limit. Note that we don't set the alarm in debugging
1773 * mode; it is just annoying to have the server exit just when you
1774 * are about to discover the bug.
1776 signal(SIGALRM, grace_alarm_handler);
1778 alarm(options.login_grace_time);
1780 sshd_exchange_identification(sock_in, sock_out);
1782 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1783 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1784 generate_ephemeral_server_key();
1786 packet_set_nonblocking();
1788 /* allocate authentication context */
1789 authctxt = xcalloc(1, sizeof(*authctxt));
1791 authctxt->loginmsg = &loginmsg;
1793 /* XXX global for cleanup, access from other modules */
1794 the_authctxt = authctxt;
1796 /* prepare buffer to collect messages to display to user after login */
1797 buffer_init(&loginmsg);
1800 if (privsep_preauth(authctxt) == 1)
1803 /* perform the key exchange */
1804 /* authenticate user and start session */
1807 do_authentication2(authctxt);
1810 do_authentication(authctxt);
1813 * If we use privilege separation, the unprivileged child transfers
1814 * the current keystate and exits
1817 mm_send_keystate(pmonitor);
1823 * Cancel the alarm we set to limit the time taken for
1827 signal(SIGALRM, SIG_DFL);
1828 authctxt->authenticated = 1;
1829 if (startup_pipe != -1) {
1830 close(startup_pipe);
1834 #ifdef SSH_AUDIT_EVENTS
1835 audit_event(SSH_AUTH_SUCCESS);
1839 if (options.gss_authentication) {
1840 temporarily_use_uid(authctxt->pw);
1841 ssh_gssapi_storecreds();
1846 if (options.use_pam) {
1853 * In privilege separation, we fork another child and prepare
1854 * file descriptor passing.
1857 privsep_postauth(authctxt);
1858 /* the monitor process [priv] will not return */
1860 destroy_sensitive_data();
1863 /* Start session. */
1864 do_authenticated(authctxt);
1866 /* The connection has been terminated. */
1867 verbose("Closing connection to %.100s", remote_ip);
1870 if (options.use_pam)
1872 #endif /* USE_PAM */
1874 #ifdef SSH_AUDIT_EVENTS
1875 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1887 * Decrypt session_key_int using our private server key and private host key
1888 * (key with larger modulus first).
1891 ssh1_session_key(BIGNUM *session_key_int)
1895 if (BN_cmp(sensitive_data.server_key->rsa->n,
1896 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1897 /* Server key has bigger modulus. */
1898 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1899 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1900 SSH_KEY_BITS_RESERVED) {
1901 fatal("do_connection: %s: "
1902 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1903 get_remote_ipaddr(),
1904 BN_num_bits(sensitive_data.server_key->rsa->n),
1905 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1906 SSH_KEY_BITS_RESERVED);
1908 if (rsa_private_decrypt(session_key_int, session_key_int,
1909 sensitive_data.server_key->rsa) <= 0)
1911 if (rsa_private_decrypt(session_key_int, session_key_int,
1912 sensitive_data.ssh1_host_key->rsa) <= 0)
1915 /* Host key has bigger modulus (or they are equal). */
1916 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1917 BN_num_bits(sensitive_data.server_key->rsa->n) +
1918 SSH_KEY_BITS_RESERVED) {
1919 fatal("do_connection: %s: "
1920 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1921 get_remote_ipaddr(),
1922 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1923 BN_num_bits(sensitive_data.server_key->rsa->n),
1924 SSH_KEY_BITS_RESERVED);
1926 if (rsa_private_decrypt(session_key_int, session_key_int,
1927 sensitive_data.ssh1_host_key->rsa) < 0)
1929 if (rsa_private_decrypt(session_key_int, session_key_int,
1930 sensitive_data.server_key->rsa) < 0)
1943 BIGNUM *session_key_int;
1944 u_char session_key[SSH_SESSION_KEY_LENGTH];
1946 u_int cipher_type, auth_mask, protocol_flags;
1949 * Generate check bytes that the client must send back in the user
1950 * packet in order for it to be accepted; this is used to defy ip
1951 * spoofing attacks. Note that this only works against somebody
1952 * doing IP spoofing from a remote machine; any machine on the local
1953 * network can still see outgoing packets and catch the random
1954 * cookie. This only affects rhosts authentication, and this is one
1955 * of the reasons why it is inherently insecure.
1957 arc4random_buf(cookie, sizeof(cookie));
1960 * Send our public key. We include in the packet 64 bits of random
1961 * data that must be matched in the reply in order to prevent IP
1964 packet_start(SSH_SMSG_PUBLIC_KEY);
1965 for (i = 0; i < 8; i++)
1966 packet_put_char(cookie[i]);
1968 /* Store our public server RSA key. */
1969 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1970 packet_put_bignum(sensitive_data.server_key->rsa->e);
1971 packet_put_bignum(sensitive_data.server_key->rsa->n);
1973 /* Store our public host RSA key. */
1974 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1975 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1976 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1978 /* Put protocol flags. */
1979 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1981 /* Declare which ciphers we support. */
1982 packet_put_int(cipher_mask_ssh1(0));
1984 /* Declare supported authentication types. */
1986 if (options.rhosts_rsa_authentication)
1987 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1988 if (options.rsa_authentication)
1989 auth_mask |= 1 << SSH_AUTH_RSA;
1990 if (options.challenge_response_authentication == 1)
1991 auth_mask |= 1 << SSH_AUTH_TIS;
1992 if (options.password_authentication)
1993 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1994 packet_put_int(auth_mask);
1996 /* Send the packet and wait for it to be sent. */
1998 packet_write_wait();
2000 debug("Sent %d bit server key and %d bit host key.",
2001 BN_num_bits(sensitive_data.server_key->rsa->n),
2002 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2004 /* Read clients reply (cipher type and session key). */
2005 packet_read_expect(SSH_CMSG_SESSION_KEY);
2007 /* Get cipher type and check whether we accept this. */
2008 cipher_type = packet_get_char();
2010 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2011 packet_disconnect("Warning: client selects unsupported cipher.");
2013 /* Get check bytes from the packet. These must match those we
2014 sent earlier with the public key packet. */
2015 for (i = 0; i < 8; i++)
2016 if (cookie[i] != packet_get_char())
2017 packet_disconnect("IP Spoofing check bytes do not match.");
2019 debug("Encryption type: %.200s", cipher_name(cipher_type));
2021 /* Get the encrypted integer. */
2022 if ((session_key_int = BN_new()) == NULL)
2023 fatal("do_ssh1_kex: BN_new failed");
2024 packet_get_bignum(session_key_int);
2026 protocol_flags = packet_get_int();
2027 packet_set_protocol_flags(protocol_flags);
2030 /* Decrypt session_key_int using host/server keys */
2031 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2034 * Extract session key from the decrypted integer. The key is in the
2035 * least significant 256 bits of the integer; the first byte of the
2036 * key is in the highest bits.
2039 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2040 len = BN_num_bytes(session_key_int);
2041 if (len < 0 || (u_int)len > sizeof(session_key)) {
2042 error("do_ssh1_kex: bad session key len from %s: "
2043 "session_key_int %d > sizeof(session_key) %lu",
2044 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2047 memset(session_key, 0, sizeof(session_key));
2048 BN_bn2bin(session_key_int,
2049 session_key + sizeof(session_key) - len);
2051 derive_ssh1_session_id(
2052 sensitive_data.ssh1_host_key->rsa->n,
2053 sensitive_data.server_key->rsa->n,
2054 cookie, session_id);
2056 * Xor the first 16 bytes of the session key with the
2059 for (i = 0; i < 16; i++)
2060 session_key[i] ^= session_id[i];
2064 int bytes = BN_num_bytes(session_key_int);
2065 u_char *buf = xmalloc(bytes);
2068 logit("do_connection: generating a fake encryption key");
2069 BN_bn2bin(session_key_int, buf);
2071 MD5_Update(&md, buf, bytes);
2072 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2073 MD5_Final(session_key, &md);
2075 MD5_Update(&md, session_key, 16);
2076 MD5_Update(&md, buf, bytes);
2077 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2078 MD5_Final(session_key + 16, &md);
2079 memset(buf, 0, bytes);
2081 for (i = 0; i < 16; i++)
2082 session_id[i] = session_key[i] ^ session_key[i + 16];
2084 /* Destroy the private and public keys. No longer. */
2085 destroy_sensitive_data();
2088 mm_ssh1_session_id(session_id);
2090 /* Destroy the decrypted integer. It is no longer needed. */
2091 BN_clear_free(session_key_int);
2093 /* Set the session key. From this on all communications will be encrypted. */
2094 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2096 /* Destroy our copy of the session key. It is no longer needed. */
2097 memset(session_key, 0, sizeof(session_key));
2099 debug("Received session key; encryption turned on.");
2101 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2102 packet_start(SSH_SMSG_SUCCESS);
2104 packet_write_wait();
2108 * SSH2 key exchange: diffie-hellman-group1-sha1
2115 if (options.ciphers != NULL) {
2116 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2117 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2119 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2120 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2121 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2122 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2124 if (options.macs != NULL) {
2125 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2126 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2128 if (options.compression == COMP_NONE) {
2129 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2130 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2131 } else if (options.compression == COMP_DELAYED) {
2132 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2133 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2136 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2138 /* start key exchange */
2139 kex = kex_setup(myproposal);
2140 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2141 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2142 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2143 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2145 kex->client_version_string=client_version_string;
2146 kex->server_version_string=server_version_string;
2147 kex->load_host_key=&get_hostkey_by_type;
2148 kex->host_key_index=&get_hostkey_index;
2152 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2154 session_id2 = kex->session_id;
2155 session_id2_len = kex->session_id_len;
2158 /* send 1st encrypted/maced/compressed message */
2159 packet_start(SSH2_MSG_IGNORE);
2160 packet_put_cstring("markus");
2162 packet_write_wait();
2167 /* server specific fatal cleanup */
2172 do_cleanup(the_authctxt);
2173 #ifdef SSH_AUDIT_EVENTS
2174 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2175 if (!use_privsep || mm_is_monitor())
2176 audit_event(SSH_CONNECTION_ABANDON);