1 /* $OpenBSD: sshd.c,v 1.359 2008/06/10 08:17:40 jmc 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"
57 #include "openbsd-compat/sys-queue.h"
75 #include <openssl/dh.h>
76 #include <openssl/bn.h>
77 #include <openssl/md5.h>
78 #include <openssl/rand.h>
79 #include "openbsd-compat/openssl-compat.h"
81 #ifdef HAVE_SECUREWARE
82 #include <sys/security.h>
102 #include "myproposal.h"
103 #include "authfile.h"
104 #include "pathnames.h"
105 #include "atomicio.h"
106 #include "canohost.h"
107 #include "hostfile.h"
111 #include "dispatch.h"
112 #include "channels.h"
114 #include "monitor_mm.h"
119 #include "monitor_wrap.h"
120 #include "monitor_fdpass.h"
135 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
136 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
137 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
138 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
140 extern char *__progname;
142 /* Server configuration options. */
143 ServerOptions options;
145 /* Name of the server configuration file. */
146 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
149 * Debug mode flag. This can be set on the command line. If debug
150 * mode is enabled, extra debugging output will be sent to the system
151 * log, the daemon will not go to background, and will exit after processing
152 * the first connection.
156 /* Flag indicating that the daemon should only test the configuration and keys. */
159 /* Flag indicating that the daemon is being started from inetd. */
162 /* Flag indicating that sshd should not detach and become a daemon. */
163 int no_daemon_flag = 0;
165 /* debug goes to stderr unless inetd_flag is set */
168 /* Saved arguments to main(). */
173 int rexeced_flag = 0;
179 * The sockets that the server is listening; this is used in the SIGHUP
182 #define MAX_LISTEN_SOCKS 16
183 int listen_socks[MAX_LISTEN_SOCKS];
184 int num_listen_socks = 0;
187 * the client's version string, passed by sshd2 in compat mode. if != NULL,
188 * sshd will skip the version-number exchange
190 char *client_version_string = NULL;
191 char *server_version_string = NULL;
193 /* for rekeying XXX fixme */
197 * Any really sensitive data in the application is contained in this
198 * structure. The idea is that this structure could be locked into memory so
199 * that the pages do not get written into swap. However, there are some
200 * problems. The private key contains BIGNUMs, and we do not (in principle)
201 * have access to the internals of them, and locking just the structure is
202 * not very useful. Currently, memory locking is not implemented.
205 Key *server_key; /* ephemeral server key */
206 Key *ssh1_host_key; /* ssh1 host key */
207 Key **host_keys; /* all private host keys */
210 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
214 * Flag indicating whether the RSA server key needs to be regenerated.
215 * Is set in the SIGALRM handler and cleared when the key is regenerated.
217 static volatile sig_atomic_t key_do_regen = 0;
219 /* This is set to true when a signal is received. */
220 static volatile sig_atomic_t received_sighup = 0;
221 static volatile sig_atomic_t received_sigterm = 0;
223 /* session identifier, used by RSA-auth */
224 u_char session_id[16];
227 u_char *session_id2 = NULL;
228 u_int session_id2_len = 0;
230 /* record remote hostname or ip */
231 u_int utmp_len = MAXHOSTNAMELEN;
233 /* options.max_startup sized array of fd ints */
234 int *startup_pipes = NULL;
235 int startup_pipe; /* in child */
237 /* variables used for privilege separation */
238 int use_privsep = -1;
239 struct monitor *pmonitor = NULL;
241 /* global authentication context */
242 Authctxt *the_authctxt = NULL;
244 /* sshd_config buffer */
247 /* message to be displayed after login */
250 /* Unprivileged user */
251 struct passwd *privsep_pw = NULL;
253 /* Prototypes for various functions defined later in this file. */
254 void destroy_sensitive_data(void);
255 void demote_sensitive_data(void);
257 static void do_ssh1_kex(void);
258 static void do_ssh2_kex(void);
261 * Close all listening sockets
264 close_listen_socks(void)
268 for (i = 0; i < num_listen_socks; i++)
269 close(listen_socks[i]);
270 num_listen_socks = -1;
274 close_startup_pipes(void)
279 for (i = 0; i < options.max_startups; i++)
280 if (startup_pipes[i] != -1)
281 close(startup_pipes[i]);
285 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
286 * the effect is to reread the configuration file (and to regenerate
292 sighup_handler(int sig)
294 int save_errno = errno;
297 signal(SIGHUP, sighup_handler);
302 * Called from the main program after receiving SIGHUP.
303 * Restarts the server.
308 logit("Received SIGHUP; restarting.");
309 close_listen_socks();
310 close_startup_pipes();
311 alarm(0); /* alarm timer persists across exec */
312 execv(saved_argv[0], saved_argv);
313 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
319 * Generic signal handler for terminating signals in the master daemon.
323 sigterm_handler(int sig)
325 received_sigterm = sig;
329 * SIGCHLD handler. This is called whenever a child dies. This will then
330 * reap any zombies left by exited children.
334 main_sigchld_handler(int sig)
336 int save_errno = errno;
340 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
341 (pid < 0 && errno == EINTR))
344 signal(SIGCHLD, main_sigchld_handler);
349 * Signal handler for the alarm after the login grace period has expired.
353 grace_alarm_handler(int sig)
355 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
356 kill(pmonitor->m_pid, SIGALRM);
358 /* Log error and exit. */
359 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
363 * Signal handler for the key regeneration alarm. Note that this
364 * alarm only occurs in the daemon waiting for connections, and it does not
365 * do anything with the private key or random state before forking.
366 * Thus there should be no concurrency control/asynchronous execution
370 generate_ephemeral_server_key(void)
372 verbose("Generating %s%d bit RSA key.",
373 sensitive_data.server_key ? "new " : "", options.server_key_bits);
374 if (sensitive_data.server_key != NULL)
375 key_free(sensitive_data.server_key);
376 sensitive_data.server_key = key_generate(KEY_RSA1,
377 options.server_key_bits);
378 verbose("RSA key generation complete.");
380 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
386 key_regeneration_alarm(int sig)
388 int save_errno = errno;
390 signal(SIGALRM, SIG_DFL);
396 sshd_exchange_identification(int sock_in, int sock_out)
400 int remote_major, remote_minor;
403 char buf[256]; /* Must not be larger than remote_version. */
404 char remote_version[256]; /* Must be at least as big as buf. */
406 if ((options.protocol & SSH_PROTO_1) &&
407 (options.protocol & SSH_PROTO_2)) {
408 major = PROTOCOL_MAJOR_1;
410 } else if (options.protocol & SSH_PROTO_2) {
411 major = PROTOCOL_MAJOR_2;
412 minor = PROTOCOL_MINOR_2;
414 major = PROTOCOL_MAJOR_1;
415 minor = PROTOCOL_MINOR_1;
417 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
418 server_version_string = xstrdup(buf);
420 /* Send our protocol version identification. */
421 if (atomicio(vwrite, sock_out, server_version_string,
422 strlen(server_version_string))
423 != strlen(server_version_string)) {
424 logit("Could not write ident string to %s", get_remote_ipaddr());
428 /* Read other sides version identification. */
429 memset(buf, 0, sizeof(buf));
430 for (i = 0; i < sizeof(buf) - 1; i++) {
431 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
432 logit("Did not receive identification string from %s",
433 get_remote_ipaddr());
436 if (buf[i] == '\r') {
438 /* Kludge for F-Secure Macintosh < 1.0.2 */
440 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
444 if (buf[i] == '\n') {
449 buf[sizeof(buf) - 1] = 0;
450 client_version_string = xstrdup(buf);
453 * Check that the versions match. In future this might accept
454 * several versions and set appropriate flags to handle them.
456 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
457 &remote_major, &remote_minor, remote_version) != 3) {
458 s = "Protocol mismatch.\n";
459 (void) atomicio(vwrite, sock_out, s, strlen(s));
462 logit("Bad protocol version identification '%.100s' from %s",
463 client_version_string, get_remote_ipaddr());
466 debug("Client protocol version %d.%d; client software version %.100s",
467 remote_major, remote_minor, remote_version);
469 compat_datafellows(remote_version);
471 if (datafellows & SSH_BUG_PROBE) {
472 logit("probed from %s with %s. Don't panic.",
473 get_remote_ipaddr(), client_version_string);
477 if (datafellows & SSH_BUG_SCANNER) {
478 logit("scanned from %s with %s. Don't panic.",
479 get_remote_ipaddr(), client_version_string);
484 switch (remote_major) {
486 if (remote_minor == 99) {
487 if (options.protocol & SSH_PROTO_2)
493 if (!(options.protocol & SSH_PROTO_1)) {
497 if (remote_minor < 3) {
498 packet_disconnect("Your ssh version is too old and "
499 "is no longer supported. Please install a newer version.");
500 } else if (remote_minor == 3) {
501 /* note that this disables agent-forwarding */
506 if (options.protocol & SSH_PROTO_2) {
515 chop(server_version_string);
516 debug("Local version string %.200s", server_version_string);
519 s = "Protocol major versions differ.\n";
520 (void) atomicio(vwrite, sock_out, s, strlen(s));
523 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
525 server_version_string, client_version_string);
530 /* Destroy the host and server keys. They will no longer be needed. */
532 destroy_sensitive_data(void)
536 if (sensitive_data.server_key) {
537 key_free(sensitive_data.server_key);
538 sensitive_data.server_key = NULL;
540 for (i = 0; i < options.num_host_key_files; i++) {
541 if (sensitive_data.host_keys[i]) {
542 key_free(sensitive_data.host_keys[i]);
543 sensitive_data.host_keys[i] = NULL;
546 sensitive_data.ssh1_host_key = NULL;
547 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
550 /* Demote private to public keys for network child */
552 demote_sensitive_data(void)
557 if (sensitive_data.server_key) {
558 tmp = key_demote(sensitive_data.server_key);
559 key_free(sensitive_data.server_key);
560 sensitive_data.server_key = tmp;
563 for (i = 0; i < options.num_host_key_files; i++) {
564 if (sensitive_data.host_keys[i]) {
565 tmp = key_demote(sensitive_data.host_keys[i]);
566 key_free(sensitive_data.host_keys[i]);
567 sensitive_data.host_keys[i] = tmp;
568 if (tmp->type == KEY_RSA1)
569 sensitive_data.ssh1_host_key = tmp;
573 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
577 privsep_preauth_child(void)
582 /* Enable challenge-response authentication for privilege separation */
583 privsep_challenge_enable();
586 arc4random_buf(rnd, sizeof(rnd));
587 RAND_seed(rnd, sizeof(rnd));
589 /* Demote the private keys to public keys. */
590 demote_sensitive_data();
592 /* Change our root directory */
593 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
594 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
596 if (chdir("/") == -1)
597 fatal("chdir(\"/\"): %s", strerror(errno));
599 /* Drop our privileges */
600 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
601 (u_int)privsep_pw->pw_gid);
603 /* XXX not ready, too heavy after chroot */
604 do_setusercontext(privsep_pw);
606 gidset[0] = privsep_pw->pw_gid;
607 if (setgroups(1, gidset) < 0)
608 fatal("setgroups: %.100s", strerror(errno));
609 permanently_set_uid(privsep_pw);
614 privsep_preauth(Authctxt *authctxt)
619 /* Set up unprivileged child process to deal with network data */
620 pmonitor = monitor_init();
621 /* Store a pointer to the kex for later rekeying */
622 pmonitor->m_pkex = &xxx_kex;
626 fatal("fork of unprivileged child failed");
627 } else if (pid != 0) {
628 debug2("Network child is on pid %ld", (long)pid);
630 close(pmonitor->m_recvfd);
631 pmonitor->m_pid = pid;
632 monitor_child_preauth(authctxt, pmonitor);
633 close(pmonitor->m_sendfd);
636 monitor_sync(pmonitor);
638 /* Wait for the child's exit status */
639 while (waitpid(pid, &status, 0) < 0)
646 close(pmonitor->m_sendfd);
648 /* Demote the child */
649 if (getuid() == 0 || geteuid() == 0)
650 privsep_preauth_child();
651 setproctitle("%s", "[net]");
657 privsep_postauth(Authctxt *authctxt)
661 #ifdef DISABLE_FD_PASSING
664 if (authctxt->pw->pw_uid == 0 || options.use_login) {
666 /* File descriptor passing is broken or root login */
671 /* New socket pair */
672 monitor_reinit(pmonitor);
674 pmonitor->m_pid = fork();
675 if (pmonitor->m_pid == -1)
676 fatal("fork of unprivileged child failed");
677 else if (pmonitor->m_pid != 0) {
678 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
679 close(pmonitor->m_recvfd);
680 buffer_clear(&loginmsg);
681 monitor_child_postauth(pmonitor);
687 close(pmonitor->m_sendfd);
689 /* Demote the private keys to public keys. */
690 demote_sensitive_data();
693 arc4random_buf(rnd, sizeof(rnd));
694 RAND_seed(rnd, sizeof(rnd));
696 /* Drop privileges */
697 do_setusercontext(authctxt->pw);
700 /* It is safe now to apply the key state */
701 monitor_apply_keystate(pmonitor);
704 * Tell the packet layer that authentication was successful, since
705 * this information is not part of the key state.
707 packet_set_authenticated();
711 list_hostkey_types(void)
719 for (i = 0; i < options.num_host_key_files; i++) {
720 Key *key = sensitive_data.host_keys[i];
726 if (buffer_len(&b) > 0)
727 buffer_append(&b, ",", 1);
728 p = key_ssh_name(key);
729 buffer_append(&b, p, strlen(p));
733 buffer_append(&b, "\0", 1);
734 ret = xstrdup(buffer_ptr(&b));
736 debug("list_hostkey_types: %s", ret);
741 get_hostkey_by_type(int type)
745 for (i = 0; i < options.num_host_key_files; i++) {
746 Key *key = sensitive_data.host_keys[i];
747 if (key != NULL && key->type == type)
754 get_hostkey_by_index(int ind)
756 if (ind < 0 || ind >= options.num_host_key_files)
758 return (sensitive_data.host_keys[ind]);
762 get_hostkey_index(Key *key)
766 for (i = 0; i < options.num_host_key_files; i++) {
767 if (key == sensitive_data.host_keys[i])
774 * returns 1 if connection should be dropped, 0 otherwise.
775 * dropping starts at connection #max_startups_begin with a probability
776 * of (max_startups_rate/100). the probability increases linearly until
777 * all connections are dropped for startups > max_startups
780 drop_connection(int startups)
784 if (startups < options.max_startups_begin)
786 if (startups >= options.max_startups)
788 if (options.max_startups_rate == 100)
791 p = 100 - options.max_startups_rate;
792 p *= startups - options.max_startups_begin;
793 p /= options.max_startups - options.max_startups_begin;
794 p += options.max_startups_rate;
795 r = arc4random_uniform(100);
797 debug("drop_connection: p %d, r %d", p, r);
798 return (r < p) ? 1 : 0;
804 fprintf(stderr, "%s, %s\n",
805 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
807 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n"
808 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n"
809 " [-o option] [-p port] [-u len]\n"
815 send_rexec_state(int fd, Buffer *conf)
819 debug3("%s: entering fd = %d config len %d", __func__, fd,
823 * Protocol from reexec master to child:
824 * string configuration
825 * u_int ephemeral_key_follows
826 * bignum e (only if ephemeral_key_follows == 1)
832 * string rngseed (only if OpenSSL is not self-seeded)
835 buffer_put_cstring(&m, buffer_ptr(conf));
837 if (sensitive_data.server_key != NULL &&
838 sensitive_data.server_key->type == KEY_RSA1) {
839 buffer_put_int(&m, 1);
840 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
841 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
842 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
843 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
844 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
845 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
847 buffer_put_int(&m, 0);
849 #ifndef OPENSSL_PRNG_ONLY
850 rexec_send_rng_seed(&m);
853 if (ssh_msg_send(fd, 0, &m) == -1)
854 fatal("%s: ssh_msg_send failed", __func__);
858 debug3("%s: done", __func__);
862 recv_rexec_state(int fd, Buffer *conf)
868 debug3("%s: entering fd = %d", __func__, fd);
872 if (ssh_msg_recv(fd, &m) == -1)
873 fatal("%s: ssh_msg_recv failed", __func__);
874 if (buffer_get_char(&m) != 0)
875 fatal("%s: rexec version mismatch", __func__);
877 cp = buffer_get_string(&m, &len);
879 buffer_append(conf, cp, len + 1);
882 if (buffer_get_int(&m)) {
883 if (sensitive_data.server_key != NULL)
884 key_free(sensitive_data.server_key);
885 sensitive_data.server_key = key_new_private(KEY_RSA1);
886 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
887 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
888 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
889 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
890 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
891 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
892 rsa_generate_additional_parameters(
893 sensitive_data.server_key->rsa);
896 #ifndef OPENSSL_PRNG_ONLY
897 rexec_recv_rng_seed(&m);
902 debug3("%s: done", __func__);
905 /* Accept a connection from inetd */
907 server_accept_inetd(int *sock_in, int *sock_out)
913 close(REEXEC_CONFIG_PASS_FD);
914 *sock_in = *sock_out = dup(STDIN_FILENO);
916 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
917 close(REEXEC_STARTUP_PIPE_FD);
920 *sock_in = dup(STDIN_FILENO);
921 *sock_out = dup(STDOUT_FILENO);
924 * We intentionally do not close the descriptors 0, 1, and 2
925 * as our code for setting the descriptors won't work if
926 * ttyfd happens to be one of those.
928 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
929 dup2(fd, STDIN_FILENO);
930 dup2(fd, STDOUT_FILENO);
931 if (fd > STDOUT_FILENO)
934 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
938 * Listen for TCP connections
943 int ret, listen_sock, on = 1;
945 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
947 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
948 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
950 if (num_listen_socks >= MAX_LISTEN_SOCKS)
951 fatal("Too many listen sockets. "
952 "Enlarge MAX_LISTEN_SOCKS");
953 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
954 ntop, sizeof(ntop), strport, sizeof(strport),
955 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
956 error("getnameinfo failed: %.100s",
957 ssh_gai_strerror(ret));
960 /* Create socket for listening. */
961 listen_sock = socket(ai->ai_family, ai->ai_socktype,
963 if (listen_sock < 0) {
964 /* kernel may not support ipv6 */
965 verbose("socket: %.100s", strerror(errno));
968 if (set_nonblock(listen_sock) == -1) {
973 * Set socket options.
974 * Allow local port reuse in TIME_WAIT.
976 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
977 &on, sizeof(on)) == -1)
978 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
981 /* Only communicate in IPv6 over AF_INET6 sockets. */
982 if (ai->ai_family == AF_INET6) {
983 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY,
984 &on, sizeof(on)) == -1)
985 error("setsockopt IPV6_V6ONLY: %s",
990 debug("Bind to port %s on %s.", strport, ntop);
992 /* Bind the socket to the desired port. */
993 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
994 error("Bind to port %s on %s failed: %.200s.",
995 strport, ntop, strerror(errno));
999 listen_socks[num_listen_socks] = listen_sock;
1002 /* Start listening on the port. */
1003 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1004 fatal("listen on [%s]:%s: %.100s",
1005 ntop, strport, strerror(errno));
1006 logit("Server listening on %s port %s.", ntop, strport);
1008 freeaddrinfo(options.listen_addrs);
1010 if (!num_listen_socks)
1011 fatal("Cannot bind any address.");
1015 * The main TCP accept loop. Note that, for the non-debug case, returns
1016 * from this function are in a forked subprocess.
1019 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1022 int i, j, ret, maxfd;
1023 int key_used = 0, startups = 0;
1024 int startup_p[2] = { -1 , -1 };
1025 struct sockaddr_storage from;
1029 /* setup fd set for accept */
1032 for (i = 0; i < num_listen_socks; i++)
1033 if (listen_socks[i] > maxfd)
1034 maxfd = listen_socks[i];
1035 /* pipes connected to unauthenticated childs */
1036 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1037 for (i = 0; i < options.max_startups; i++)
1038 startup_pipes[i] = -1;
1041 * Stay listening for connections until the system crashes or
1042 * the daemon is killed with a signal.
1045 if (received_sighup)
1049 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1052 for (i = 0; i < num_listen_socks; i++)
1053 FD_SET(listen_socks[i], fdset);
1054 for (i = 0; i < options.max_startups; i++)
1055 if (startup_pipes[i] != -1)
1056 FD_SET(startup_pipes[i], fdset);
1058 /* Wait in select until there is a connection. */
1059 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1060 if (ret < 0 && errno != EINTR)
1061 error("select: %.100s", strerror(errno));
1062 if (received_sigterm) {
1063 logit("Received signal %d; terminating.",
1064 (int) received_sigterm);
1065 close_listen_socks();
1066 unlink(options.pid_file);
1069 if (key_used && key_do_regen) {
1070 generate_ephemeral_server_key();
1077 for (i = 0; i < options.max_startups; i++)
1078 if (startup_pipes[i] != -1 &&
1079 FD_ISSET(startup_pipes[i], fdset)) {
1081 * the read end of the pipe is ready
1082 * if the child has closed the pipe
1083 * after successful authentication
1084 * or if the child has died
1086 close(startup_pipes[i]);
1087 startup_pipes[i] = -1;
1090 for (i = 0; i < num_listen_socks; i++) {
1091 if (!FD_ISSET(listen_socks[i], fdset))
1093 fromlen = sizeof(from);
1094 *newsock = accept(listen_socks[i],
1095 (struct sockaddr *)&from, &fromlen);
1097 if (errno != EINTR && errno != EWOULDBLOCK)
1098 error("accept: %.100s", strerror(errno));
1101 if (unset_nonblock(*newsock) == -1) {
1105 if (drop_connection(startups) == 1) {
1106 debug("drop connection #%d", startups);
1110 if (pipe(startup_p) == -1) {
1115 if (rexec_flag && socketpair(AF_UNIX,
1116 SOCK_STREAM, 0, config_s) == -1) {
1117 error("reexec socketpair: %s",
1120 close(startup_p[0]);
1121 close(startup_p[1]);
1125 for (j = 0; j < options.max_startups; j++)
1126 if (startup_pipes[j] == -1) {
1127 startup_pipes[j] = startup_p[0];
1128 if (maxfd < startup_p[0])
1129 maxfd = startup_p[0];
1135 * Got connection. Fork a child to handle it, unless
1136 * we are in debugging mode.
1140 * In debugging mode. Close the listening
1141 * socket, and start processing the
1142 * connection without forking.
1144 debug("Server will not fork when running in debugging mode.");
1145 close_listen_socks();
1146 *sock_in = *newsock;
1147 *sock_out = *newsock;
1148 close(startup_p[0]);
1149 close(startup_p[1]);
1153 send_rexec_state(config_s[0],
1161 * Normal production daemon. Fork, and have
1162 * the child process the connection. The
1163 * parent continues listening.
1165 platform_pre_fork();
1166 if ((pid = fork()) == 0) {
1168 * Child. Close the listening and
1169 * max_startup sockets. Start using
1170 * the accepted socket. Reinitialize
1171 * logging (since our pid has changed).
1172 * We break out of the loop to handle
1175 platform_post_fork_child();
1176 startup_pipe = startup_p[1];
1177 close_startup_pipes();
1178 close_listen_socks();
1179 *sock_in = *newsock;
1180 *sock_out = *newsock;
1181 log_init(__progname,
1183 options.log_facility,
1190 /* Parent. Stay in the loop. */
1191 platform_post_fork_parent(pid);
1193 error("fork: %.100s", strerror(errno));
1195 debug("Forked child %ld.", (long)pid);
1197 close(startup_p[1]);
1200 send_rexec_state(config_s[0], &cfg);
1206 * Mark that the key has been used (it
1207 * was "given" to the child).
1209 if ((options.protocol & SSH_PROTO_1) &&
1211 /* Schedule server key regeneration alarm. */
1212 signal(SIGALRM, key_regeneration_alarm);
1213 alarm(options.key_regeneration_time);
1220 * Ensure that our random state differs
1221 * from that of the child
1226 /* child process check (or debug mode) */
1227 if (num_listen_socks < 0)
1234 * Main program for the daemon.
1237 main(int ac, char **av)
1239 extern char *optarg;
1242 int sock_in = -1, sock_out = -1, newsock = -1;
1243 const char *remote_ip;
1244 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1246 char *line, *p, *cp;
1247 int config_s[2] = { -1 , -1 };
1251 #ifdef HAVE_SECUREWARE
1252 (void)set_auth_parameters(ac, av);
1254 __progname = ssh_get_progname(av[0]);
1257 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1260 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1261 for (i = 0; i < ac; i++)
1262 saved_argv[i] = xstrdup(av[i]);
1263 saved_argv[i] = NULL;
1265 #ifndef HAVE_SETPROCTITLE
1266 /* Prepare for later setproctitle emulation */
1267 compat_init_setproctitle(ac, av);
1271 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1272 debug("setgroups(): %.200s", strerror(errno));
1274 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1277 /* Initialize configuration options to their default values. */
1278 initialize_server_options(&options);
1280 /* Parse command-line arguments. */
1281 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1284 options.address_family = AF_INET;
1287 options.address_family = AF_INET6;
1290 config_file_name = optarg;
1293 if (debug_flag == 0) {
1295 options.log_level = SYSLOG_LEVEL_DEBUG1;
1296 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1297 options.log_level++;
1319 options.log_level = SYSLOG_LEVEL_QUIET;
1322 options.server_key_bits = (int)strtonum(optarg, 256,
1326 options.ports_from_cmdline = 1;
1327 if (options.num_ports >= MAX_PORTS) {
1328 fprintf(stderr, "too many ports.\n");
1331 options.ports[options.num_ports++] = a2port(optarg);
1332 if (options.ports[options.num_ports-1] == 0) {
1333 fprintf(stderr, "Bad port number.\n");
1338 if ((options.login_grace_time = convtime(optarg)) == -1) {
1339 fprintf(stderr, "Invalid login grace time.\n");
1344 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1345 fprintf(stderr, "Invalid key regeneration interval.\n");
1350 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1351 fprintf(stderr, "too many host keys.\n");
1354 options.host_key_files[options.num_host_key_files++] = optarg;
1364 while ((p = strsep(&cp, ",")) && *p != '\0') {
1365 if (strncmp(p, "addr=", 5) == 0)
1366 test_addr = xstrdup(p + 5);
1367 else if (strncmp(p, "host=", 5) == 0)
1368 test_host = xstrdup(p + 5);
1369 else if (strncmp(p, "user=", 5) == 0)
1370 test_user = xstrdup(p + 5);
1372 fprintf(stderr, "Invalid test "
1373 "mode specification %s\n", p);
1379 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1380 if (utmp_len > MAXHOSTNAMELEN) {
1381 fprintf(stderr, "Invalid utmp length.\n");
1386 line = xstrdup(optarg);
1387 if (process_server_config_line(&options, line,
1388 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1398 if (rexeced_flag || inetd_flag)
1400 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1401 fatal("sshd re-exec requires execution with an absolute path");
1403 closefrom(REEXEC_MIN_FREE_FD);
1405 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1407 SSLeay_add_all_algorithms();
1410 * Force logging to stderr until we have loaded the private host
1411 * key (unless started from inetd)
1413 log_init(__progname,
1414 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1415 SYSLOG_LEVEL_INFO : options.log_level,
1416 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1417 SYSLOG_FACILITY_AUTH : options.log_facility,
1418 log_stderr || !inetd_flag);
1421 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1422 * root's environment
1424 if (getenv("KRB5CCNAME") != NULL)
1425 unsetenv("KRB5CCNAME");
1428 /* Cray can define user privs drop all privs now!
1429 * Not needed on PRIV_SU systems!
1434 sensitive_data.server_key = NULL;
1435 sensitive_data.ssh1_host_key = NULL;
1436 sensitive_data.have_ssh1_key = 0;
1437 sensitive_data.have_ssh2_key = 0;
1440 * If we're doing an extended config test, make sure we have all of
1441 * the parameters we need. If we're not doing an extended test,
1442 * do not silently ignore connection test params.
1444 if (test_flag >= 2 && (test_user != NULL || test_host != NULL || test_addr != NULL)
1445 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1446 fatal("user, host and addr are all required when testing "
1448 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1450 fatal("Config test connection parameter (-C) provided without "
1453 /* Fetch our configuration */
1456 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1458 load_server_config(config_file_name, &cfg);
1460 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1461 &cfg, NULL, NULL, NULL);
1465 /* Fill in default values for those options not explicitly set. */
1466 fill_default_server_options(&options);
1468 /* challenge-response is implemented via keyboard interactive */
1469 if (options.challenge_response_authentication)
1470 options.kbd_interactive_authentication = 1;
1472 /* set default channel AF */
1473 channel_set_af(options.address_family);
1475 /* Check that there are no remaining arguments. */
1477 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1481 debug("sshd version %.100s", SSH_RELEASE);
1483 /* Store privilege separation user for later use if required. */
1484 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1485 if (use_privsep || options.kerberos_authentication)
1486 fatal("Privilege separation user %s does not exist",
1489 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1490 privsep_pw = pwcopy(privsep_pw);
1491 xfree(privsep_pw->pw_passwd);
1492 privsep_pw->pw_passwd = xstrdup("*");
1496 /* load private host keys */
1497 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1499 for (i = 0; i < options.num_host_key_files; i++)
1500 sensitive_data.host_keys[i] = NULL;
1502 for (i = 0; i < options.num_host_key_files; i++) {
1503 key = key_load_private(options.host_key_files[i], "", NULL);
1504 sensitive_data.host_keys[i] = key;
1506 error("Could not load host key: %s",
1507 options.host_key_files[i]);
1508 sensitive_data.host_keys[i] = NULL;
1511 switch (key->type) {
1513 sensitive_data.ssh1_host_key = key;
1514 sensitive_data.have_ssh1_key = 1;
1518 sensitive_data.have_ssh2_key = 1;
1521 debug("private host key: #%d type %d %s", i, key->type,
1524 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1525 logit("Disabling protocol version 1. Could not load host key");
1526 options.protocol &= ~SSH_PROTO_1;
1528 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1529 logit("Disabling protocol version 2. Could not load host key");
1530 options.protocol &= ~SSH_PROTO_2;
1532 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1533 logit("sshd: no hostkeys available -- exiting.");
1537 /* Check certain values for sanity. */
1538 if (options.protocol & SSH_PROTO_1) {
1539 if (options.server_key_bits < 512 ||
1540 options.server_key_bits > 32768) {
1541 fprintf(stderr, "Bad server key size.\n");
1545 * Check that server and host key lengths differ sufficiently. This
1546 * is necessary to make double encryption work with rsaref. Oh, I
1547 * hate software patents. I dont know if this can go? Niels
1549 if (options.server_key_bits >
1550 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1551 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1552 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1553 SSH_KEY_BITS_RESERVED) {
1554 options.server_key_bits =
1555 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1556 SSH_KEY_BITS_RESERVED;
1557 debug("Forcing server key to %d bits to make it differ from host key.",
1558 options.server_key_bits);
1565 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1566 (S_ISDIR(st.st_mode) == 0))
1567 fatal("Missing privilege separation directory: %s",
1568 _PATH_PRIVSEP_CHROOT_DIR);
1571 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1572 (st.st_uid != getuid () ||
1573 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1575 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1577 fatal("%s must be owned by root and not group or "
1578 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1581 if (test_flag > 1) {
1582 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1583 parse_server_match_config(&options, test_user,
1584 test_host, test_addr);
1585 dump_config(&options);
1588 /* Configuration looks good, so exit if in test mode. */
1593 * Clear out any supplemental groups we may have inherited. This
1594 * prevents inadvertent creation of files with bad modes (in the
1595 * portable version at least, it's certainly possible for PAM
1596 * to create a file, and we can't control the code in every
1597 * module which might be used).
1599 if (setgroups(0, NULL) < 0)
1600 debug("setgroups() failed: %.200s", strerror(errno));
1603 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1604 for (i = 0; i < rexec_argc; i++) {
1605 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1606 rexec_argv[i] = saved_argv[i];
1608 rexec_argv[rexec_argc] = "-R";
1609 rexec_argv[rexec_argc + 1] = NULL;
1612 /* Initialize the log (it is reinitialized below in case we forked). */
1613 if (debug_flag && (!inetd_flag || rexeced_flag))
1615 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1618 * If not in debugging mode, and not started from inetd, disconnect
1619 * from the controlling terminal, and fork. The original process
1622 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1625 #endif /* TIOCNOTTY */
1626 if (daemon(0, 0) < 0)
1627 fatal("daemon() failed: %.200s", strerror(errno));
1629 /* Disconnect from the controlling tty. */
1631 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1633 (void) ioctl(fd, TIOCNOTTY, NULL);
1636 #endif /* TIOCNOTTY */
1638 /* Reinitialize the log (because of the fork above). */
1639 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1641 /* Initialize the random number generator. */
1644 /* Chdir to the root directory so that the current disk can be
1645 unmounted if desired. */
1648 /* ignore SIGPIPE */
1649 signal(SIGPIPE, SIG_IGN);
1651 /* Get a connection, either from inetd or a listening TCP socket */
1653 server_accept_inetd(&sock_in, &sock_out);
1657 if (options.protocol & SSH_PROTO_1)
1658 generate_ephemeral_server_key();
1660 signal(SIGHUP, sighup_handler);
1661 signal(SIGCHLD, main_sigchld_handler);
1662 signal(SIGTERM, sigterm_handler);
1663 signal(SIGQUIT, sigterm_handler);
1666 * Write out the pid file after the sigterm handler
1667 * is setup and the listen sockets are bound
1670 FILE *f = fopen(options.pid_file, "w");
1673 error("Couldn't create pid file \"%s\": %s",
1674 options.pid_file, strerror(errno));
1676 fprintf(f, "%ld\n", (long) getpid());
1681 /* Accept a connection and return in a forked child */
1682 server_accept_loop(&sock_in, &sock_out,
1683 &newsock, config_s);
1686 /* This is the child processing a new connection. */
1687 setproctitle("%s", "[accepted]");
1690 * Create a new session and process group since the 4.4BSD
1691 * setlogin() affects the entire process group. We don't
1692 * want the child to be able to affect the parent.
1694 #if !defined(SSHD_ACQUIRES_CTTY)
1696 * If setsid is called, on some platforms sshd will later acquire a
1697 * controlling terminal which will result in "could not set
1698 * controlling tty" errors.
1700 if (!debug_flag && !inetd_flag && setsid() < 0)
1701 error("setsid: %.100s", strerror(errno));
1707 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1708 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1709 dup2(newsock, STDIN_FILENO);
1710 dup2(STDIN_FILENO, STDOUT_FILENO);
1711 if (startup_pipe == -1)
1712 close(REEXEC_STARTUP_PIPE_FD);
1714 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1716 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1718 if (startup_pipe != -1)
1719 close(startup_pipe);
1721 execv(rexec_argv[0], rexec_argv);
1723 /* Reexec has failed, fall back and continue */
1724 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1725 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1726 log_init(__progname, options.log_level,
1727 options.log_facility, log_stderr);
1730 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1732 close(REEXEC_CONFIG_PASS_FD);
1733 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1734 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1735 dup2(fd, STDIN_FILENO);
1736 dup2(fd, STDOUT_FILENO);
1737 if (fd > STDERR_FILENO)
1740 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1741 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1745 * Disable the key regeneration alarm. We will not regenerate the
1746 * key since we are no longer in a position to give it to anyone. We
1747 * will not restart on SIGHUP since it no longer makes sense.
1750 signal(SIGALRM, SIG_DFL);
1751 signal(SIGHUP, SIG_DFL);
1752 signal(SIGTERM, SIG_DFL);
1753 signal(SIGQUIT, SIG_DFL);
1754 signal(SIGCHLD, SIG_DFL);
1755 signal(SIGINT, SIG_DFL);
1758 * Register our connection. This turns encryption off because we do
1761 packet_set_connection(sock_in, sock_out);
1762 packet_set_server();
1764 /* Set SO_KEEPALIVE if requested. */
1765 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1766 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1767 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1769 if ((remote_port = get_remote_port()) < 0) {
1770 debug("get_remote_port failed");
1775 * We use get_canonical_hostname with usedns = 0 instead of
1776 * get_remote_ipaddr here so IP options will be checked.
1778 (void) get_canonical_hostname(0);
1780 * The rest of the code depends on the fact that
1781 * get_remote_ipaddr() caches the remote ip, even if
1782 * the socket goes away.
1784 remote_ip = get_remote_ipaddr();
1786 #ifdef SSH_AUDIT_EVENTS
1787 audit_connection_from(remote_ip, remote_port);
1790 allow_severity = options.log_facility|LOG_INFO;
1791 deny_severity = options.log_facility|LOG_WARNING;
1792 /* Check whether logins are denied from this host. */
1793 if (packet_connection_is_on_socket()) {
1794 struct request_info req;
1796 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1799 if (!hosts_access(&req)) {
1800 debug("Connection refused by tcp wrapper");
1803 fatal("libwrap refuse returns");
1806 #endif /* LIBWRAP */
1808 /* Log the connection. */
1809 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1812 * We don't want to listen forever unless the other side
1813 * successfully authenticates itself. So we set up an alarm which is
1814 * cleared after successful authentication. A limit of zero
1815 * indicates no limit. Note that we don't set the alarm in debugging
1816 * mode; it is just annoying to have the server exit just when you
1817 * are about to discover the bug.
1819 signal(SIGALRM, grace_alarm_handler);
1821 alarm(options.login_grace_time);
1823 sshd_exchange_identification(sock_in, sock_out);
1825 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1826 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1827 generate_ephemeral_server_key();
1829 packet_set_nonblocking();
1831 /* allocate authentication context */
1832 authctxt = xcalloc(1, sizeof(*authctxt));
1834 authctxt->loginmsg = &loginmsg;
1836 /* XXX global for cleanup, access from other modules */
1837 the_authctxt = authctxt;
1839 /* prepare buffer to collect messages to display to user after login */
1840 buffer_init(&loginmsg);
1843 if (privsep_preauth(authctxt) == 1)
1846 /* perform the key exchange */
1847 /* authenticate user and start session */
1850 do_authentication2(authctxt);
1853 do_authentication(authctxt);
1856 * If we use privilege separation, the unprivileged child transfers
1857 * the current keystate and exits
1860 mm_send_keystate(pmonitor);
1866 * Cancel the alarm we set to limit the time taken for
1870 signal(SIGALRM, SIG_DFL);
1871 authctxt->authenticated = 1;
1872 if (startup_pipe != -1) {
1873 close(startup_pipe);
1877 #ifdef SSH_AUDIT_EVENTS
1878 audit_event(SSH_AUTH_SUCCESS);
1882 if (options.gss_authentication) {
1883 temporarily_use_uid(authctxt->pw);
1884 ssh_gssapi_storecreds();
1889 if (options.use_pam) {
1896 * In privilege separation, we fork another child and prepare
1897 * file descriptor passing.
1900 privsep_postauth(authctxt);
1901 /* the monitor process [priv] will not return */
1903 destroy_sensitive_data();
1906 /* Start session. */
1907 do_authenticated(authctxt);
1909 /* The connection has been terminated. */
1910 verbose("Closing connection to %.100s", remote_ip);
1913 if (options.use_pam)
1915 #endif /* USE_PAM */
1917 #ifdef SSH_AUDIT_EVENTS
1918 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1930 * Decrypt session_key_int using our private server key and private host key
1931 * (key with larger modulus first).
1934 ssh1_session_key(BIGNUM *session_key_int)
1938 if (BN_cmp(sensitive_data.server_key->rsa->n,
1939 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1940 /* Server key has bigger modulus. */
1941 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1942 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1943 SSH_KEY_BITS_RESERVED) {
1944 fatal("do_connection: %s: "
1945 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1946 get_remote_ipaddr(),
1947 BN_num_bits(sensitive_data.server_key->rsa->n),
1948 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1949 SSH_KEY_BITS_RESERVED);
1951 if (rsa_private_decrypt(session_key_int, session_key_int,
1952 sensitive_data.server_key->rsa) <= 0)
1954 if (rsa_private_decrypt(session_key_int, session_key_int,
1955 sensitive_data.ssh1_host_key->rsa) <= 0)
1958 /* Host key has bigger modulus (or they are equal). */
1959 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1960 BN_num_bits(sensitive_data.server_key->rsa->n) +
1961 SSH_KEY_BITS_RESERVED) {
1962 fatal("do_connection: %s: "
1963 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1964 get_remote_ipaddr(),
1965 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1966 BN_num_bits(sensitive_data.server_key->rsa->n),
1967 SSH_KEY_BITS_RESERVED);
1969 if (rsa_private_decrypt(session_key_int, session_key_int,
1970 sensitive_data.ssh1_host_key->rsa) < 0)
1972 if (rsa_private_decrypt(session_key_int, session_key_int,
1973 sensitive_data.server_key->rsa) < 0)
1986 BIGNUM *session_key_int;
1987 u_char session_key[SSH_SESSION_KEY_LENGTH];
1989 u_int cipher_type, auth_mask, protocol_flags;
1992 * Generate check bytes that the client must send back in the user
1993 * packet in order for it to be accepted; this is used to defy ip
1994 * spoofing attacks. Note that this only works against somebody
1995 * doing IP spoofing from a remote machine; any machine on the local
1996 * network can still see outgoing packets and catch the random
1997 * cookie. This only affects rhosts authentication, and this is one
1998 * of the reasons why it is inherently insecure.
2000 arc4random_buf(cookie, sizeof(cookie));
2003 * Send our public key. We include in the packet 64 bits of random
2004 * data that must be matched in the reply in order to prevent IP
2007 packet_start(SSH_SMSG_PUBLIC_KEY);
2008 for (i = 0; i < 8; i++)
2009 packet_put_char(cookie[i]);
2011 /* Store our public server RSA key. */
2012 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2013 packet_put_bignum(sensitive_data.server_key->rsa->e);
2014 packet_put_bignum(sensitive_data.server_key->rsa->n);
2016 /* Store our public host RSA key. */
2017 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2018 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2019 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2021 /* Put protocol flags. */
2022 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2024 /* Declare which ciphers we support. */
2025 packet_put_int(cipher_mask_ssh1(0));
2027 /* Declare supported authentication types. */
2029 if (options.rhosts_rsa_authentication)
2030 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2031 if (options.rsa_authentication)
2032 auth_mask |= 1 << SSH_AUTH_RSA;
2033 if (options.challenge_response_authentication == 1)
2034 auth_mask |= 1 << SSH_AUTH_TIS;
2035 if (options.password_authentication)
2036 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2037 packet_put_int(auth_mask);
2039 /* Send the packet and wait for it to be sent. */
2041 packet_write_wait();
2043 debug("Sent %d bit server key and %d bit host key.",
2044 BN_num_bits(sensitive_data.server_key->rsa->n),
2045 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2047 /* Read clients reply (cipher type and session key). */
2048 packet_read_expect(SSH_CMSG_SESSION_KEY);
2050 /* Get cipher type and check whether we accept this. */
2051 cipher_type = packet_get_char();
2053 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2054 packet_disconnect("Warning: client selects unsupported cipher.");
2056 /* Get check bytes from the packet. These must match those we
2057 sent earlier with the public key packet. */
2058 for (i = 0; i < 8; i++)
2059 if (cookie[i] != packet_get_char())
2060 packet_disconnect("IP Spoofing check bytes do not match.");
2062 debug("Encryption type: %.200s", cipher_name(cipher_type));
2064 /* Get the encrypted integer. */
2065 if ((session_key_int = BN_new()) == NULL)
2066 fatal("do_ssh1_kex: BN_new failed");
2067 packet_get_bignum(session_key_int);
2069 protocol_flags = packet_get_int();
2070 packet_set_protocol_flags(protocol_flags);
2073 /* Decrypt session_key_int using host/server keys */
2074 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2077 * Extract session key from the decrypted integer. The key is in the
2078 * least significant 256 bits of the integer; the first byte of the
2079 * key is in the highest bits.
2082 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2083 len = BN_num_bytes(session_key_int);
2084 if (len < 0 || (u_int)len > sizeof(session_key)) {
2085 error("do_ssh1_kex: bad session key len from %s: "
2086 "session_key_int %d > sizeof(session_key) %lu",
2087 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2090 memset(session_key, 0, sizeof(session_key));
2091 BN_bn2bin(session_key_int,
2092 session_key + sizeof(session_key) - len);
2094 derive_ssh1_session_id(
2095 sensitive_data.ssh1_host_key->rsa->n,
2096 sensitive_data.server_key->rsa->n,
2097 cookie, session_id);
2099 * Xor the first 16 bytes of the session key with the
2102 for (i = 0; i < 16; i++)
2103 session_key[i] ^= session_id[i];
2107 int bytes = BN_num_bytes(session_key_int);
2108 u_char *buf = xmalloc(bytes);
2111 logit("do_connection: generating a fake encryption key");
2112 BN_bn2bin(session_key_int, buf);
2114 MD5_Update(&md, buf, bytes);
2115 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2116 MD5_Final(session_key, &md);
2118 MD5_Update(&md, session_key, 16);
2119 MD5_Update(&md, buf, bytes);
2120 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2121 MD5_Final(session_key + 16, &md);
2122 memset(buf, 0, bytes);
2124 for (i = 0; i < 16; i++)
2125 session_id[i] = session_key[i] ^ session_key[i + 16];
2127 /* Destroy the private and public keys. No longer. */
2128 destroy_sensitive_data();
2131 mm_ssh1_session_id(session_id);
2133 /* Destroy the decrypted integer. It is no longer needed. */
2134 BN_clear_free(session_key_int);
2136 /* Set the session key. From this on all communications will be encrypted. */
2137 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2139 /* Destroy our copy of the session key. It is no longer needed. */
2140 memset(session_key, 0, sizeof(session_key));
2142 debug("Received session key; encryption turned on.");
2144 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2145 packet_start(SSH_SMSG_SUCCESS);
2147 packet_write_wait();
2151 * SSH2 key exchange: diffie-hellman-group1-sha1
2158 if (options.ciphers != NULL) {
2159 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2160 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2162 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2163 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2164 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2165 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2167 if (options.macs != NULL) {
2168 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2169 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2171 if (options.compression == COMP_NONE) {
2172 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2173 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2174 } else if (options.compression == COMP_DELAYED) {
2175 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2176 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2179 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2181 /* start key exchange */
2182 kex = kex_setup(myproposal);
2183 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2184 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2185 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2186 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2188 kex->client_version_string=client_version_string;
2189 kex->server_version_string=server_version_string;
2190 kex->load_host_key=&get_hostkey_by_type;
2191 kex->host_key_index=&get_hostkey_index;
2195 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2197 session_id2 = kex->session_id;
2198 session_id2_len = kex->session_id_len;
2201 /* send 1st encrypted/maced/compressed message */
2202 packet_start(SSH2_MSG_IGNORE);
2203 packet_put_cstring("markus");
2205 packet_write_wait();
2210 /* server specific fatal cleanup */
2215 do_cleanup(the_authctxt);
2216 #ifdef SSH_AUDIT_EVENTS
2217 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2218 if (!use_privsep || mm_is_monitor())
2219 audit_event(SSH_CONNECTION_ABANDON);