1 /* $OpenBSD: sshd.c,v 1.366 2009/01/22 10:02:34 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"
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"
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;
401 char *s, *newline = "\n";
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;
414 major = PROTOCOL_MAJOR_1;
415 minor = PROTOCOL_MINOR_1;
417 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
418 SSH_VERSION, newline);
419 server_version_string = xstrdup(buf);
421 /* Send our protocol version identification. */
422 if (atomicio(vwrite, sock_out, server_version_string,
423 strlen(server_version_string))
424 != strlen(server_version_string)) {
425 logit("Could not write ident string to %s", get_remote_ipaddr());
429 /* Read other sides version identification. */
430 memset(buf, 0, sizeof(buf));
431 for (i = 0; i < sizeof(buf) - 1; i++) {
432 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
433 logit("Did not receive identification string from %s",
434 get_remote_ipaddr());
437 if (buf[i] == '\r') {
439 /* Kludge for F-Secure Macintosh < 1.0.2 */
441 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
445 if (buf[i] == '\n') {
450 buf[sizeof(buf) - 1] = 0;
451 client_version_string = xstrdup(buf);
454 * Check that the versions match. In future this might accept
455 * several versions and set appropriate flags to handle them.
457 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
458 &remote_major, &remote_minor, remote_version) != 3) {
459 s = "Protocol mismatch.\n";
460 (void) atomicio(vwrite, sock_out, s, strlen(s));
463 logit("Bad protocol version identification '%.100s' from %s",
464 client_version_string, get_remote_ipaddr());
467 debug("Client protocol version %d.%d; client software version %.100s",
468 remote_major, remote_minor, remote_version);
470 compat_datafellows(remote_version);
472 if (datafellows & SSH_BUG_PROBE) {
473 logit("probed from %s with %s. Don't panic.",
474 get_remote_ipaddr(), client_version_string);
478 if (datafellows & SSH_BUG_SCANNER) {
479 logit("scanned from %s with %s. Don't panic.",
480 get_remote_ipaddr(), client_version_string);
485 switch (remote_major) {
487 if (remote_minor == 99) {
488 if (options.protocol & SSH_PROTO_2)
494 if (!(options.protocol & SSH_PROTO_1)) {
498 if (remote_minor < 3) {
499 packet_disconnect("Your ssh version is too old and "
500 "is no longer supported. Please install a newer version.");
501 } else if (remote_minor == 3) {
502 /* note that this disables agent-forwarding */
507 if (options.protocol & SSH_PROTO_2) {
516 chop(server_version_string);
517 debug("Local version string %.200s", server_version_string);
520 s = "Protocol major versions differ.\n";
521 (void) atomicio(vwrite, sock_out, s, strlen(s));
524 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
526 server_version_string, client_version_string);
531 /* Destroy the host and server keys. They will no longer be needed. */
533 destroy_sensitive_data(void)
537 if (sensitive_data.server_key) {
538 key_free(sensitive_data.server_key);
539 sensitive_data.server_key = NULL;
541 for (i = 0; i < options.num_host_key_files; i++) {
542 if (sensitive_data.host_keys[i]) {
543 key_free(sensitive_data.host_keys[i]);
544 sensitive_data.host_keys[i] = NULL;
547 sensitive_data.ssh1_host_key = NULL;
548 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
551 /* Demote private to public keys for network child */
553 demote_sensitive_data(void)
558 if (sensitive_data.server_key) {
559 tmp = key_demote(sensitive_data.server_key);
560 key_free(sensitive_data.server_key);
561 sensitive_data.server_key = tmp;
564 for (i = 0; i < options.num_host_key_files; i++) {
565 if (sensitive_data.host_keys[i]) {
566 tmp = key_demote(sensitive_data.host_keys[i]);
567 key_free(sensitive_data.host_keys[i]);
568 sensitive_data.host_keys[i] = tmp;
569 if (tmp->type == KEY_RSA1)
570 sensitive_data.ssh1_host_key = tmp;
574 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
578 privsep_preauth_child(void)
583 /* Enable challenge-response authentication for privilege separation */
584 privsep_challenge_enable();
587 arc4random_buf(rnd, sizeof(rnd));
588 RAND_seed(rnd, sizeof(rnd));
590 /* Demote the private keys to public keys. */
591 demote_sensitive_data();
593 /* Change our root directory */
594 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
595 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
597 if (chdir("/") == -1)
598 fatal("chdir(\"/\"): %s", strerror(errno));
600 /* Drop our privileges */
601 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
602 (u_int)privsep_pw->pw_gid);
604 /* XXX not ready, too heavy after chroot */
605 do_setusercontext(privsep_pw);
607 gidset[0] = privsep_pw->pw_gid;
608 if (setgroups(1, gidset) < 0)
609 fatal("setgroups: %.100s", strerror(errno));
610 permanently_set_uid(privsep_pw);
615 privsep_preauth(Authctxt *authctxt)
620 /* Set up unprivileged child process to deal with network data */
621 pmonitor = monitor_init();
622 /* Store a pointer to the kex for later rekeying */
623 pmonitor->m_pkex = &xxx_kex;
627 fatal("fork of unprivileged child failed");
628 } else if (pid != 0) {
629 debug2("Network child is on pid %ld", (long)pid);
631 close(pmonitor->m_recvfd);
632 pmonitor->m_pid = pid;
633 monitor_child_preauth(authctxt, pmonitor);
634 close(pmonitor->m_sendfd);
637 monitor_sync(pmonitor);
639 /* Wait for the child's exit status */
640 while (waitpid(pid, &status, 0) < 0)
647 close(pmonitor->m_sendfd);
649 /* Demote the child */
650 if (getuid() == 0 || geteuid() == 0)
651 privsep_preauth_child();
652 setproctitle("%s", "[net]");
658 privsep_postauth(Authctxt *authctxt)
662 #ifdef DISABLE_FD_PASSING
665 if (authctxt->pw->pw_uid == 0 || options.use_login) {
667 /* File descriptor passing is broken or root login */
672 /* New socket pair */
673 monitor_reinit(pmonitor);
675 pmonitor->m_pid = fork();
676 if (pmonitor->m_pid == -1)
677 fatal("fork of unprivileged child failed");
678 else if (pmonitor->m_pid != 0) {
679 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
680 close(pmonitor->m_recvfd);
681 buffer_clear(&loginmsg);
682 monitor_child_postauth(pmonitor);
688 close(pmonitor->m_sendfd);
690 /* Demote the private keys to public keys. */
691 demote_sensitive_data();
694 arc4random_buf(rnd, sizeof(rnd));
695 RAND_seed(rnd, sizeof(rnd));
697 /* Drop privileges */
698 do_setusercontext(authctxt->pw);
701 /* It is safe now to apply the key state */
702 monitor_apply_keystate(pmonitor);
705 * Tell the packet layer that authentication was successful, since
706 * this information is not part of the key state.
708 packet_set_authenticated();
712 list_hostkey_types(void)
720 for (i = 0; i < options.num_host_key_files; i++) {
721 Key *key = sensitive_data.host_keys[i];
727 if (buffer_len(&b) > 0)
728 buffer_append(&b, ",", 1);
729 p = key_ssh_name(key);
730 buffer_append(&b, p, strlen(p));
734 buffer_append(&b, "\0", 1);
735 ret = xstrdup(buffer_ptr(&b));
737 debug("list_hostkey_types: %s", ret);
742 get_hostkey_by_type(int type)
746 for (i = 0; i < options.num_host_key_files; i++) {
747 Key *key = sensitive_data.host_keys[i];
748 if (key != NULL && key->type == type)
755 get_hostkey_by_index(int ind)
757 if (ind < 0 || ind >= options.num_host_key_files)
759 return (sensitive_data.host_keys[ind]);
763 get_hostkey_index(Key *key)
767 for (i = 0; i < options.num_host_key_files; i++) {
768 if (key == sensitive_data.host_keys[i])
775 * returns 1 if connection should be dropped, 0 otherwise.
776 * dropping starts at connection #max_startups_begin with a probability
777 * of (max_startups_rate/100). the probability increases linearly until
778 * all connections are dropped for startups > max_startups
781 drop_connection(int startups)
785 if (startups < options.max_startups_begin)
787 if (startups >= options.max_startups)
789 if (options.max_startups_rate == 100)
792 p = 100 - options.max_startups_rate;
793 p *= startups - options.max_startups_begin;
794 p /= options.max_startups - options.max_startups_begin;
795 p += options.max_startups_rate;
796 r = arc4random_uniform(100);
798 debug("drop_connection: p %d, r %d", p, r);
799 return (r < p) ? 1 : 0;
805 fprintf(stderr, "%s, %s\n",
806 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
808 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n"
809 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n"
810 " [-o option] [-p port] [-u len]\n"
816 send_rexec_state(int fd, Buffer *conf)
820 debug3("%s: entering fd = %d config len %d", __func__, fd,
824 * Protocol from reexec master to child:
825 * string configuration
826 * u_int ephemeral_key_follows
827 * bignum e (only if ephemeral_key_follows == 1)
833 * string rngseed (only if OpenSSL is not self-seeded)
836 buffer_put_cstring(&m, buffer_ptr(conf));
838 if (sensitive_data.server_key != NULL &&
839 sensitive_data.server_key->type == KEY_RSA1) {
840 buffer_put_int(&m, 1);
841 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
842 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
843 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
844 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
845 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
846 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
848 buffer_put_int(&m, 0);
850 #ifndef OPENSSL_PRNG_ONLY
851 rexec_send_rng_seed(&m);
854 if (ssh_msg_send(fd, 0, &m) == -1)
855 fatal("%s: ssh_msg_send failed", __func__);
859 debug3("%s: done", __func__);
863 recv_rexec_state(int fd, Buffer *conf)
869 debug3("%s: entering fd = %d", __func__, fd);
873 if (ssh_msg_recv(fd, &m) == -1)
874 fatal("%s: ssh_msg_recv failed", __func__);
875 if (buffer_get_char(&m) != 0)
876 fatal("%s: rexec version mismatch", __func__);
878 cp = buffer_get_string(&m, &len);
880 buffer_append(conf, cp, len + 1);
883 if (buffer_get_int(&m)) {
884 if (sensitive_data.server_key != NULL)
885 key_free(sensitive_data.server_key);
886 sensitive_data.server_key = key_new_private(KEY_RSA1);
887 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
888 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
889 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
890 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
891 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
892 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
893 rsa_generate_additional_parameters(
894 sensitive_data.server_key->rsa);
897 #ifndef OPENSSL_PRNG_ONLY
898 rexec_recv_rng_seed(&m);
903 debug3("%s: done", __func__);
906 /* Accept a connection from inetd */
908 server_accept_inetd(int *sock_in, int *sock_out)
914 close(REEXEC_CONFIG_PASS_FD);
915 *sock_in = *sock_out = dup(STDIN_FILENO);
917 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
918 close(REEXEC_STARTUP_PIPE_FD);
921 *sock_in = dup(STDIN_FILENO);
922 *sock_out = dup(STDOUT_FILENO);
925 * We intentionally do not close the descriptors 0, 1, and 2
926 * as our code for setting the descriptors won't work if
927 * ttyfd happens to be one of those.
929 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
930 dup2(fd, STDIN_FILENO);
931 dup2(fd, STDOUT_FILENO);
932 if (fd > STDOUT_FILENO)
935 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
939 * Listen for TCP connections
944 int ret, listen_sock, on = 1;
946 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
948 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
949 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
951 if (num_listen_socks >= MAX_LISTEN_SOCKS)
952 fatal("Too many listen sockets. "
953 "Enlarge MAX_LISTEN_SOCKS");
954 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
955 ntop, sizeof(ntop), strport, sizeof(strport),
956 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
957 error("getnameinfo failed: %.100s",
958 ssh_gai_strerror(ret));
961 /* Create socket for listening. */
962 listen_sock = socket(ai->ai_family, ai->ai_socktype,
964 if (listen_sock < 0) {
965 /* kernel may not support ipv6 */
966 verbose("socket: %.100s", strerror(errno));
969 if (set_nonblock(listen_sock) == -1) {
974 * Set socket options.
975 * Allow local port reuse in TIME_WAIT.
977 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
978 &on, sizeof(on)) == -1)
979 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
982 /* Only communicate in IPv6 over AF_INET6 sockets. */
983 if (ai->ai_family == AF_INET6) {
984 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY,
985 &on, sizeof(on)) == -1)
986 error("setsockopt IPV6_V6ONLY: %s",
991 debug("Bind to port %s on %s.", strport, ntop);
993 /* Bind the socket to the desired port. */
994 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
995 error("Bind to port %s on %s failed: %.200s.",
996 strport, ntop, strerror(errno));
1000 listen_socks[num_listen_socks] = listen_sock;
1003 /* Start listening on the port. */
1004 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1005 fatal("listen on [%s]:%s: %.100s",
1006 ntop, strport, strerror(errno));
1007 logit("Server listening on %s port %s.", ntop, strport);
1009 freeaddrinfo(options.listen_addrs);
1011 if (!num_listen_socks)
1012 fatal("Cannot bind any address.");
1016 * The main TCP accept loop. Note that, for the non-debug case, returns
1017 * from this function are in a forked subprocess.
1020 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1023 int i, j, ret, maxfd;
1024 int key_used = 0, startups = 0;
1025 int startup_p[2] = { -1 , -1 };
1026 struct sockaddr_storage from;
1030 /* setup fd set for accept */
1033 for (i = 0; i < num_listen_socks; i++)
1034 if (listen_socks[i] > maxfd)
1035 maxfd = listen_socks[i];
1036 /* pipes connected to unauthenticated childs */
1037 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1038 for (i = 0; i < options.max_startups; i++)
1039 startup_pipes[i] = -1;
1042 * Stay listening for connections until the system crashes or
1043 * the daemon is killed with a signal.
1046 if (received_sighup)
1050 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1053 for (i = 0; i < num_listen_socks; i++)
1054 FD_SET(listen_socks[i], fdset);
1055 for (i = 0; i < options.max_startups; i++)
1056 if (startup_pipes[i] != -1)
1057 FD_SET(startup_pipes[i], fdset);
1059 /* Wait in select until there is a connection. */
1060 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1061 if (ret < 0 && errno != EINTR)
1062 error("select: %.100s", strerror(errno));
1063 if (received_sigterm) {
1064 logit("Received signal %d; terminating.",
1065 (int) received_sigterm);
1066 close_listen_socks();
1067 unlink(options.pid_file);
1070 if (key_used && key_do_regen) {
1071 generate_ephemeral_server_key();
1078 for (i = 0; i < options.max_startups; i++)
1079 if (startup_pipes[i] != -1 &&
1080 FD_ISSET(startup_pipes[i], fdset)) {
1082 * the read end of the pipe is ready
1083 * if the child has closed the pipe
1084 * after successful authentication
1085 * or if the child has died
1087 close(startup_pipes[i]);
1088 startup_pipes[i] = -1;
1091 for (i = 0; i < num_listen_socks; i++) {
1092 if (!FD_ISSET(listen_socks[i], fdset))
1094 fromlen = sizeof(from);
1095 *newsock = accept(listen_socks[i],
1096 (struct sockaddr *)&from, &fromlen);
1098 if (errno != EINTR && errno != EAGAIN &&
1099 errno != EWOULDBLOCK)
1100 error("accept: %.100s", strerror(errno));
1103 if (unset_nonblock(*newsock) == -1) {
1107 if (drop_connection(startups) == 1) {
1108 debug("drop connection #%d", startups);
1112 if (pipe(startup_p) == -1) {
1117 if (rexec_flag && socketpair(AF_UNIX,
1118 SOCK_STREAM, 0, config_s) == -1) {
1119 error("reexec socketpair: %s",
1122 close(startup_p[0]);
1123 close(startup_p[1]);
1127 for (j = 0; j < options.max_startups; j++)
1128 if (startup_pipes[j] == -1) {
1129 startup_pipes[j] = startup_p[0];
1130 if (maxfd < startup_p[0])
1131 maxfd = startup_p[0];
1137 * Got connection. Fork a child to handle it, unless
1138 * we are in debugging mode.
1142 * In debugging mode. Close the listening
1143 * socket, and start processing the
1144 * connection without forking.
1146 debug("Server will not fork when running in debugging mode.");
1147 close_listen_socks();
1148 *sock_in = *newsock;
1149 *sock_out = *newsock;
1150 close(startup_p[0]);
1151 close(startup_p[1]);
1155 send_rexec_state(config_s[0],
1163 * Normal production daemon. Fork, and have
1164 * the child process the connection. The
1165 * parent continues listening.
1167 platform_pre_fork();
1168 if ((pid = fork()) == 0) {
1170 * Child. Close the listening and
1171 * max_startup sockets. Start using
1172 * the accepted socket. Reinitialize
1173 * logging (since our pid has changed).
1174 * We break out of the loop to handle
1177 platform_post_fork_child();
1178 startup_pipe = startup_p[1];
1179 close_startup_pipes();
1180 close_listen_socks();
1181 *sock_in = *newsock;
1182 *sock_out = *newsock;
1183 log_init(__progname,
1185 options.log_facility,
1192 /* Parent. Stay in the loop. */
1193 platform_post_fork_parent(pid);
1195 error("fork: %.100s", strerror(errno));
1197 debug("Forked child %ld.", (long)pid);
1199 close(startup_p[1]);
1202 send_rexec_state(config_s[0], &cfg);
1208 * Mark that the key has been used (it
1209 * was "given" to the child).
1211 if ((options.protocol & SSH_PROTO_1) &&
1213 /* Schedule server key regeneration alarm. */
1214 signal(SIGALRM, key_regeneration_alarm);
1215 alarm(options.key_regeneration_time);
1222 * Ensure that our random state differs
1223 * from that of the child
1228 /* child process check (or debug mode) */
1229 if (num_listen_socks < 0)
1236 * Main program for the daemon.
1239 main(int ac, char **av)
1241 extern char *optarg;
1244 int sock_in = -1, sock_out = -1, newsock = -1;
1245 const char *remote_ip;
1246 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1248 char *line, *p, *cp;
1249 int config_s[2] = { -1 , -1 };
1250 u_int64_t ibytes, obytes;
1255 #ifdef HAVE_SECUREWARE
1256 (void)set_auth_parameters(ac, av);
1258 __progname = ssh_get_progname(av[0]);
1261 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1264 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1265 for (i = 0; i < ac; i++)
1266 saved_argv[i] = xstrdup(av[i]);
1267 saved_argv[i] = NULL;
1269 #ifndef HAVE_SETPROCTITLE
1270 /* Prepare for later setproctitle emulation */
1271 compat_init_setproctitle(ac, av);
1275 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1276 debug("setgroups(): %.200s", strerror(errno));
1278 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1281 /* Initialize configuration options to their default values. */
1282 initialize_server_options(&options);
1284 /* Parse command-line arguments. */
1285 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1288 options.address_family = AF_INET;
1291 options.address_family = AF_INET6;
1294 config_file_name = optarg;
1297 if (debug_flag == 0) {
1299 options.log_level = SYSLOG_LEVEL_DEBUG1;
1300 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1301 options.log_level++;
1323 options.log_level = SYSLOG_LEVEL_QUIET;
1326 options.server_key_bits = (int)strtonum(optarg, 256,
1330 options.ports_from_cmdline = 1;
1331 if (options.num_ports >= MAX_PORTS) {
1332 fprintf(stderr, "too many ports.\n");
1335 options.ports[options.num_ports++] = a2port(optarg);
1336 if (options.ports[options.num_ports-1] <= 0) {
1337 fprintf(stderr, "Bad port number.\n");
1342 if ((options.login_grace_time = convtime(optarg)) == -1) {
1343 fprintf(stderr, "Invalid login grace time.\n");
1348 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1349 fprintf(stderr, "Invalid key regeneration interval.\n");
1354 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1355 fprintf(stderr, "too many host keys.\n");
1358 options.host_key_files[options.num_host_key_files++] = optarg;
1368 while ((p = strsep(&cp, ",")) && *p != '\0') {
1369 if (strncmp(p, "addr=", 5) == 0)
1370 test_addr = xstrdup(p + 5);
1371 else if (strncmp(p, "host=", 5) == 0)
1372 test_host = xstrdup(p + 5);
1373 else if (strncmp(p, "user=", 5) == 0)
1374 test_user = xstrdup(p + 5);
1376 fprintf(stderr, "Invalid test "
1377 "mode specification %s\n", p);
1383 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1384 if (utmp_len > MAXHOSTNAMELEN) {
1385 fprintf(stderr, "Invalid utmp length.\n");
1390 line = xstrdup(optarg);
1391 if (process_server_config_line(&options, line,
1392 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1402 if (rexeced_flag || inetd_flag)
1404 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1405 fatal("sshd re-exec requires execution with an absolute path");
1407 closefrom(REEXEC_MIN_FREE_FD);
1409 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1411 SSLeay_add_all_algorithms();
1414 * Force logging to stderr until we have loaded the private host
1415 * key (unless started from inetd)
1417 log_init(__progname,
1418 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1419 SYSLOG_LEVEL_INFO : options.log_level,
1420 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1421 SYSLOG_FACILITY_AUTH : options.log_facility,
1422 log_stderr || !inetd_flag);
1425 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1426 * root's environment
1428 if (getenv("KRB5CCNAME") != NULL)
1429 unsetenv("KRB5CCNAME");
1432 /* Cray can define user privs drop all privs now!
1433 * Not needed on PRIV_SU systems!
1438 sensitive_data.server_key = NULL;
1439 sensitive_data.ssh1_host_key = NULL;
1440 sensitive_data.have_ssh1_key = 0;
1441 sensitive_data.have_ssh2_key = 0;
1444 * If we're doing an extended config test, make sure we have all of
1445 * the parameters we need. If we're not doing an extended test,
1446 * do not silently ignore connection test params.
1448 if (test_flag >= 2 &&
1449 (test_user != NULL || test_host != NULL || test_addr != NULL)
1450 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1451 fatal("user, host and addr are all required when testing "
1453 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1455 fatal("Config test connection parameter (-C) provided without "
1458 /* Fetch our configuration */
1461 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1463 load_server_config(config_file_name, &cfg);
1465 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1466 &cfg, NULL, NULL, NULL);
1470 /* Fill in default values for those options not explicitly set. */
1471 fill_default_server_options(&options);
1473 /* challenge-response is implemented via keyboard interactive */
1474 if (options.challenge_response_authentication)
1475 options.kbd_interactive_authentication = 1;
1477 /* set default channel AF */
1478 channel_set_af(options.address_family);
1480 /* Check that there are no remaining arguments. */
1482 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1486 debug("sshd version %.100s", SSH_RELEASE);
1488 /* Store privilege separation user for later use if required. */
1489 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1490 if (use_privsep || options.kerberos_authentication)
1491 fatal("Privilege separation user %s does not exist",
1494 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1495 privsep_pw = pwcopy(privsep_pw);
1496 xfree(privsep_pw->pw_passwd);
1497 privsep_pw->pw_passwd = xstrdup("*");
1501 /* load private host keys */
1502 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1504 for (i = 0; i < options.num_host_key_files; i++)
1505 sensitive_data.host_keys[i] = NULL;
1507 for (i = 0; i < options.num_host_key_files; i++) {
1508 key = key_load_private(options.host_key_files[i], "", NULL);
1509 sensitive_data.host_keys[i] = key;
1511 error("Could not load host key: %s",
1512 options.host_key_files[i]);
1513 sensitive_data.host_keys[i] = NULL;
1516 switch (key->type) {
1518 sensitive_data.ssh1_host_key = key;
1519 sensitive_data.have_ssh1_key = 1;
1523 sensitive_data.have_ssh2_key = 1;
1526 debug("private host key: #%d type %d %s", i, key->type,
1529 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1530 logit("Disabling protocol version 1. Could not load host key");
1531 options.protocol &= ~SSH_PROTO_1;
1533 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1534 logit("Disabling protocol version 2. Could not load host key");
1535 options.protocol &= ~SSH_PROTO_2;
1537 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1538 logit("sshd: no hostkeys available -- exiting.");
1542 /* Check certain values for sanity. */
1543 if (options.protocol & SSH_PROTO_1) {
1544 if (options.server_key_bits < 512 ||
1545 options.server_key_bits > 32768) {
1546 fprintf(stderr, "Bad server key size.\n");
1550 * Check that server and host key lengths differ sufficiently. This
1551 * is necessary to make double encryption work with rsaref. Oh, I
1552 * hate software patents. I dont know if this can go? Niels
1554 if (options.server_key_bits >
1555 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1556 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1557 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1558 SSH_KEY_BITS_RESERVED) {
1559 options.server_key_bits =
1560 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1561 SSH_KEY_BITS_RESERVED;
1562 debug("Forcing server key to %d bits to make it differ from host key.",
1563 options.server_key_bits);
1570 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1571 (S_ISDIR(st.st_mode) == 0))
1572 fatal("Missing privilege separation directory: %s",
1573 _PATH_PRIVSEP_CHROOT_DIR);
1576 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1577 (st.st_uid != getuid () ||
1578 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1580 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1582 fatal("%s must be owned by root and not group or "
1583 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1586 if (test_flag > 1) {
1587 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1588 parse_server_match_config(&options, test_user,
1589 test_host, test_addr);
1590 dump_config(&options);
1593 /* Configuration looks good, so exit if in test mode. */
1598 * Clear out any supplemental groups we may have inherited. This
1599 * prevents inadvertent creation of files with bad modes (in the
1600 * portable version at least, it's certainly possible for PAM
1601 * to create a file, and we can't control the code in every
1602 * module which might be used).
1604 if (setgroups(0, NULL) < 0)
1605 debug("setgroups() failed: %.200s", strerror(errno));
1608 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1609 for (i = 0; i < rexec_argc; i++) {
1610 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1611 rexec_argv[i] = saved_argv[i];
1613 rexec_argv[rexec_argc] = "-R";
1614 rexec_argv[rexec_argc + 1] = NULL;
1617 /* Ensure that umask disallows at least group and world write */
1618 new_umask = umask(0077) | 0022;
1619 (void) umask(new_umask);
1621 /* Initialize the log (it is reinitialized below in case we forked). */
1622 if (debug_flag && (!inetd_flag || rexeced_flag))
1624 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1627 * If not in debugging mode, and not started from inetd, disconnect
1628 * from the controlling terminal, and fork. The original process
1631 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1634 #endif /* TIOCNOTTY */
1635 if (daemon(0, 0) < 0)
1636 fatal("daemon() failed: %.200s", strerror(errno));
1638 /* Disconnect from the controlling tty. */
1640 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1642 (void) ioctl(fd, TIOCNOTTY, NULL);
1645 #endif /* TIOCNOTTY */
1647 /* Reinitialize the log (because of the fork above). */
1648 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1650 /* Initialize the random number generator. */
1653 /* Chdir to the root directory so that the current disk can be
1654 unmounted if desired. */
1657 /* ignore SIGPIPE */
1658 signal(SIGPIPE, SIG_IGN);
1660 /* Get a connection, either from inetd or a listening TCP socket */
1662 server_accept_inetd(&sock_in, &sock_out);
1666 if (options.protocol & SSH_PROTO_1)
1667 generate_ephemeral_server_key();
1669 signal(SIGHUP, sighup_handler);
1670 signal(SIGCHLD, main_sigchld_handler);
1671 signal(SIGTERM, sigterm_handler);
1672 signal(SIGQUIT, sigterm_handler);
1675 * Write out the pid file after the sigterm handler
1676 * is setup and the listen sockets are bound
1679 FILE *f = fopen(options.pid_file, "w");
1682 error("Couldn't create pid file \"%s\": %s",
1683 options.pid_file, strerror(errno));
1685 fprintf(f, "%ld\n", (long) getpid());
1690 /* Accept a connection and return in a forked child */
1691 server_accept_loop(&sock_in, &sock_out,
1692 &newsock, config_s);
1695 /* This is the child processing a new connection. */
1696 setproctitle("%s", "[accepted]");
1699 * Create a new session and process group since the 4.4BSD
1700 * setlogin() affects the entire process group. We don't
1701 * want the child to be able to affect the parent.
1703 #if !defined(SSHD_ACQUIRES_CTTY)
1705 * If setsid is called, on some platforms sshd will later acquire a
1706 * controlling terminal which will result in "could not set
1707 * controlling tty" errors.
1709 if (!debug_flag && !inetd_flag && setsid() < 0)
1710 error("setsid: %.100s", strerror(errno));
1716 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1717 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1718 dup2(newsock, STDIN_FILENO);
1719 dup2(STDIN_FILENO, STDOUT_FILENO);
1720 if (startup_pipe == -1)
1721 close(REEXEC_STARTUP_PIPE_FD);
1723 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1725 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1727 if (startup_pipe != -1)
1728 close(startup_pipe);
1730 execv(rexec_argv[0], rexec_argv);
1732 /* Reexec has failed, fall back and continue */
1733 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1734 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1735 log_init(__progname, options.log_level,
1736 options.log_facility, log_stderr);
1739 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1741 close(REEXEC_CONFIG_PASS_FD);
1742 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1743 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1744 dup2(fd, STDIN_FILENO);
1745 dup2(fd, STDOUT_FILENO);
1746 if (fd > STDERR_FILENO)
1749 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1750 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1754 * Disable the key regeneration alarm. We will not regenerate the
1755 * key since we are no longer in a position to give it to anyone. We
1756 * will not restart on SIGHUP since it no longer makes sense.
1759 signal(SIGALRM, SIG_DFL);
1760 signal(SIGHUP, SIG_DFL);
1761 signal(SIGTERM, SIG_DFL);
1762 signal(SIGQUIT, SIG_DFL);
1763 signal(SIGCHLD, SIG_DFL);
1764 signal(SIGINT, SIG_DFL);
1767 * Register our connection. This turns encryption off because we do
1770 packet_set_connection(sock_in, sock_out);
1771 packet_set_server();
1773 /* Set SO_KEEPALIVE if requested. */
1774 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1775 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1776 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1778 if ((remote_port = get_remote_port()) < 0) {
1779 debug("get_remote_port failed");
1784 * We use get_canonical_hostname with usedns = 0 instead of
1785 * get_remote_ipaddr here so IP options will be checked.
1787 (void) get_canonical_hostname(0);
1789 * The rest of the code depends on the fact that
1790 * get_remote_ipaddr() caches the remote ip, even if
1791 * the socket goes away.
1793 remote_ip = get_remote_ipaddr();
1795 #ifdef SSH_AUDIT_EVENTS
1796 audit_connection_from(remote_ip, remote_port);
1799 allow_severity = options.log_facility|LOG_INFO;
1800 deny_severity = options.log_facility|LOG_WARNING;
1801 /* Check whether logins are denied from this host. */
1802 if (packet_connection_is_on_socket()) {
1803 struct request_info req;
1805 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1808 if (!hosts_access(&req)) {
1809 debug("Connection refused by tcp wrapper");
1812 fatal("libwrap refuse returns");
1815 #endif /* LIBWRAP */
1817 /* Log the connection. */
1818 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1821 * We don't want to listen forever unless the other side
1822 * successfully authenticates itself. So we set up an alarm which is
1823 * cleared after successful authentication. A limit of zero
1824 * indicates no limit. Note that we don't set the alarm in debugging
1825 * mode; it is just annoying to have the server exit just when you
1826 * are about to discover the bug.
1828 signal(SIGALRM, grace_alarm_handler);
1830 alarm(options.login_grace_time);
1832 sshd_exchange_identification(sock_in, sock_out);
1834 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1835 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1836 generate_ephemeral_server_key();
1838 packet_set_nonblocking();
1840 /* allocate authentication context */
1841 authctxt = xcalloc(1, sizeof(*authctxt));
1843 authctxt->loginmsg = &loginmsg;
1845 /* XXX global for cleanup, access from other modules */
1846 the_authctxt = authctxt;
1848 /* prepare buffer to collect messages to display to user after login */
1849 buffer_init(&loginmsg);
1852 if (privsep_preauth(authctxt) == 1)
1855 /* perform the key exchange */
1856 /* authenticate user and start session */
1859 do_authentication2(authctxt);
1862 do_authentication(authctxt);
1865 * If we use privilege separation, the unprivileged child transfers
1866 * the current keystate and exits
1869 mm_send_keystate(pmonitor);
1875 * Cancel the alarm we set to limit the time taken for
1879 signal(SIGALRM, SIG_DFL);
1880 authctxt->authenticated = 1;
1881 if (startup_pipe != -1) {
1882 close(startup_pipe);
1886 #ifdef SSH_AUDIT_EVENTS
1887 audit_event(SSH_AUTH_SUCCESS);
1891 if (options.gss_authentication) {
1892 temporarily_use_uid(authctxt->pw);
1893 ssh_gssapi_storecreds();
1898 if (options.use_pam) {
1905 * In privilege separation, we fork another child and prepare
1906 * file descriptor passing.
1909 privsep_postauth(authctxt);
1910 /* the monitor process [priv] will not return */
1912 destroy_sensitive_data();
1915 packet_set_timeout(options.client_alive_interval,
1916 options.client_alive_count_max);
1918 /* Start session. */
1919 do_authenticated(authctxt);
1921 /* The connection has been terminated. */
1922 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
1923 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
1924 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
1926 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
1929 if (options.use_pam)
1931 #endif /* USE_PAM */
1933 #ifdef SSH_AUDIT_EVENTS
1934 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1946 * Decrypt session_key_int using our private server key and private host key
1947 * (key with larger modulus first).
1950 ssh1_session_key(BIGNUM *session_key_int)
1954 if (BN_cmp(sensitive_data.server_key->rsa->n,
1955 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1956 /* Server key has bigger modulus. */
1957 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1958 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1959 SSH_KEY_BITS_RESERVED) {
1960 fatal("do_connection: %s: "
1961 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1962 get_remote_ipaddr(),
1963 BN_num_bits(sensitive_data.server_key->rsa->n),
1964 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1965 SSH_KEY_BITS_RESERVED);
1967 if (rsa_private_decrypt(session_key_int, session_key_int,
1968 sensitive_data.server_key->rsa) <= 0)
1970 if (rsa_private_decrypt(session_key_int, session_key_int,
1971 sensitive_data.ssh1_host_key->rsa) <= 0)
1974 /* Host key has bigger modulus (or they are equal). */
1975 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1976 BN_num_bits(sensitive_data.server_key->rsa->n) +
1977 SSH_KEY_BITS_RESERVED) {
1978 fatal("do_connection: %s: "
1979 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1980 get_remote_ipaddr(),
1981 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1982 BN_num_bits(sensitive_data.server_key->rsa->n),
1983 SSH_KEY_BITS_RESERVED);
1985 if (rsa_private_decrypt(session_key_int, session_key_int,
1986 sensitive_data.ssh1_host_key->rsa) < 0)
1988 if (rsa_private_decrypt(session_key_int, session_key_int,
1989 sensitive_data.server_key->rsa) < 0)
2002 BIGNUM *session_key_int;
2003 u_char session_key[SSH_SESSION_KEY_LENGTH];
2005 u_int cipher_type, auth_mask, protocol_flags;
2008 * Generate check bytes that the client must send back in the user
2009 * packet in order for it to be accepted; this is used to defy ip
2010 * spoofing attacks. Note that this only works against somebody
2011 * doing IP spoofing from a remote machine; any machine on the local
2012 * network can still see outgoing packets and catch the random
2013 * cookie. This only affects rhosts authentication, and this is one
2014 * of the reasons why it is inherently insecure.
2016 arc4random_buf(cookie, sizeof(cookie));
2019 * Send our public key. We include in the packet 64 bits of random
2020 * data that must be matched in the reply in order to prevent IP
2023 packet_start(SSH_SMSG_PUBLIC_KEY);
2024 for (i = 0; i < 8; i++)
2025 packet_put_char(cookie[i]);
2027 /* Store our public server RSA key. */
2028 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2029 packet_put_bignum(sensitive_data.server_key->rsa->e);
2030 packet_put_bignum(sensitive_data.server_key->rsa->n);
2032 /* Store our public host RSA key. */
2033 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2034 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2035 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2037 /* Put protocol flags. */
2038 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2040 /* Declare which ciphers we support. */
2041 packet_put_int(cipher_mask_ssh1(0));
2043 /* Declare supported authentication types. */
2045 if (options.rhosts_rsa_authentication)
2046 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2047 if (options.rsa_authentication)
2048 auth_mask |= 1 << SSH_AUTH_RSA;
2049 if (options.challenge_response_authentication == 1)
2050 auth_mask |= 1 << SSH_AUTH_TIS;
2051 if (options.password_authentication)
2052 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2053 packet_put_int(auth_mask);
2055 /* Send the packet and wait for it to be sent. */
2057 packet_write_wait();
2059 debug("Sent %d bit server key and %d bit host key.",
2060 BN_num_bits(sensitive_data.server_key->rsa->n),
2061 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2063 /* Read clients reply (cipher type and session key). */
2064 packet_read_expect(SSH_CMSG_SESSION_KEY);
2066 /* Get cipher type and check whether we accept this. */
2067 cipher_type = packet_get_char();
2069 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2070 packet_disconnect("Warning: client selects unsupported cipher.");
2072 /* Get check bytes from the packet. These must match those we
2073 sent earlier with the public key packet. */
2074 for (i = 0; i < 8; i++)
2075 if (cookie[i] != packet_get_char())
2076 packet_disconnect("IP Spoofing check bytes do not match.");
2078 debug("Encryption type: %.200s", cipher_name(cipher_type));
2080 /* Get the encrypted integer. */
2081 if ((session_key_int = BN_new()) == NULL)
2082 fatal("do_ssh1_kex: BN_new failed");
2083 packet_get_bignum(session_key_int);
2085 protocol_flags = packet_get_int();
2086 packet_set_protocol_flags(protocol_flags);
2089 /* Decrypt session_key_int using host/server keys */
2090 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2093 * Extract session key from the decrypted integer. The key is in the
2094 * least significant 256 bits of the integer; the first byte of the
2095 * key is in the highest bits.
2098 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2099 len = BN_num_bytes(session_key_int);
2100 if (len < 0 || (u_int)len > sizeof(session_key)) {
2101 error("do_ssh1_kex: bad session key len from %s: "
2102 "session_key_int %d > sizeof(session_key) %lu",
2103 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2106 memset(session_key, 0, sizeof(session_key));
2107 BN_bn2bin(session_key_int,
2108 session_key + sizeof(session_key) - len);
2110 derive_ssh1_session_id(
2111 sensitive_data.ssh1_host_key->rsa->n,
2112 sensitive_data.server_key->rsa->n,
2113 cookie, session_id);
2115 * Xor the first 16 bytes of the session key with the
2118 for (i = 0; i < 16; i++)
2119 session_key[i] ^= session_id[i];
2123 int bytes = BN_num_bytes(session_key_int);
2124 u_char *buf = xmalloc(bytes);
2127 logit("do_connection: generating a fake encryption key");
2128 BN_bn2bin(session_key_int, buf);
2130 MD5_Update(&md, buf, bytes);
2131 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2132 MD5_Final(session_key, &md);
2134 MD5_Update(&md, session_key, 16);
2135 MD5_Update(&md, buf, bytes);
2136 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2137 MD5_Final(session_key + 16, &md);
2138 memset(buf, 0, bytes);
2140 for (i = 0; i < 16; i++)
2141 session_id[i] = session_key[i] ^ session_key[i + 16];
2143 /* Destroy the private and public keys. No longer. */
2144 destroy_sensitive_data();
2147 mm_ssh1_session_id(session_id);
2149 /* Destroy the decrypted integer. It is no longer needed. */
2150 BN_clear_free(session_key_int);
2152 /* Set the session key. From this on all communications will be encrypted. */
2153 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2155 /* Destroy our copy of the session key. It is no longer needed. */
2156 memset(session_key, 0, sizeof(session_key));
2158 debug("Received session key; encryption turned on.");
2160 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2161 packet_start(SSH_SMSG_SUCCESS);
2163 packet_write_wait();
2167 * SSH2 key exchange: diffie-hellman-group1-sha1
2174 if (options.ciphers != NULL) {
2175 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2176 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2178 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2179 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2180 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2181 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2183 if (options.macs != NULL) {
2184 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2185 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2187 if (options.compression == COMP_NONE) {
2188 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2189 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2190 } else if (options.compression == COMP_DELAYED) {
2191 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2192 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2195 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2197 /* start key exchange */
2198 kex = kex_setup(myproposal);
2199 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2200 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2201 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2202 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2204 kex->client_version_string=client_version_string;
2205 kex->server_version_string=server_version_string;
2206 kex->load_host_key=&get_hostkey_by_type;
2207 kex->host_key_index=&get_hostkey_index;
2211 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2213 session_id2 = kex->session_id;
2214 session_id2_len = kex->session_id_len;
2217 /* send 1st encrypted/maced/compressed message */
2218 packet_start(SSH2_MSG_IGNORE);
2219 packet_put_cstring("markus");
2221 packet_write_wait();
2226 /* server specific fatal cleanup */
2231 do_cleanup(the_authctxt);
2232 #ifdef SSH_AUDIT_EVENTS
2233 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2234 if (!use_privsep || mm_is_monitor())
2235 audit_event(SSH_CONNECTION_ABANDON);