1 /* $OpenBSD: sshd.c,v 1.381 2011/01/11 06:13:10 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"
123 #ifdef USE_SECURITY_SESSION_API
124 #include <Security/AuthSession.h>
139 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
140 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
141 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
142 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
144 extern char *__progname;
146 /* Server configuration options. */
147 ServerOptions options;
149 /* Name of the server configuration file. */
150 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
153 * Debug mode flag. This can be set on the command line. If debug
154 * mode is enabled, extra debugging output will be sent to the system
155 * log, the daemon will not go to background, and will exit after processing
156 * the first connection.
160 /* Flag indicating that the daemon should only test the configuration and keys. */
163 /* Flag indicating that the daemon is being started from inetd. */
166 /* Flag indicating that sshd should not detach and become a daemon. */
167 int no_daemon_flag = 0;
169 /* debug goes to stderr unless inetd_flag is set */
172 /* Saved arguments to main(). */
177 int rexeced_flag = 0;
183 * The sockets that the server is listening; this is used in the SIGHUP
186 #define MAX_LISTEN_SOCKS 16
187 int listen_socks[MAX_LISTEN_SOCKS];
188 int num_listen_socks = 0;
191 * the client's version string, passed by sshd2 in compat mode. if != NULL,
192 * sshd will skip the version-number exchange
194 char *client_version_string = NULL;
195 char *server_version_string = NULL;
197 /* for rekeying XXX fixme */
201 * Any really sensitive data in the application is contained in this
202 * structure. The idea is that this structure could be locked into memory so
203 * that the pages do not get written into swap. However, there are some
204 * problems. The private key contains BIGNUMs, and we do not (in principle)
205 * have access to the internals of them, and locking just the structure is
206 * not very useful. Currently, memory locking is not implemented.
209 Key *server_key; /* ephemeral server key */
210 Key *ssh1_host_key; /* ssh1 host key */
211 Key **host_keys; /* all private host keys */
212 Key **host_certificates; /* all public host certificates */
215 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
219 * Flag indicating whether the RSA server key needs to be regenerated.
220 * Is set in the SIGALRM handler and cleared when the key is regenerated.
222 static volatile sig_atomic_t key_do_regen = 0;
224 /* This is set to true when a signal is received. */
225 static volatile sig_atomic_t received_sighup = 0;
226 static volatile sig_atomic_t received_sigterm = 0;
228 /* session identifier, used by RSA-auth */
229 u_char session_id[16];
232 u_char *session_id2 = NULL;
233 u_int session_id2_len = 0;
235 /* record remote hostname or ip */
236 u_int utmp_len = MAXHOSTNAMELEN;
238 /* options.max_startup sized array of fd ints */
239 int *startup_pipes = NULL;
240 int startup_pipe; /* in child */
242 /* variables used for privilege separation */
243 int use_privsep = -1;
244 struct monitor *pmonitor = NULL;
246 /* global authentication context */
247 Authctxt *the_authctxt = NULL;
249 /* sshd_config buffer */
252 /* message to be displayed after login */
255 /* Unprivileged user */
256 struct passwd *privsep_pw = NULL;
258 /* Prototypes for various functions defined later in this file. */
259 void destroy_sensitive_data(void);
260 void demote_sensitive_data(void);
262 static void do_ssh1_kex(void);
263 static void do_ssh2_kex(void);
266 * Close all listening sockets
269 close_listen_socks(void)
273 for (i = 0; i < num_listen_socks; i++)
274 close(listen_socks[i]);
275 num_listen_socks = -1;
279 close_startup_pipes(void)
284 for (i = 0; i < options.max_startups; i++)
285 if (startup_pipes[i] != -1)
286 close(startup_pipes[i]);
290 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
291 * the effect is to reread the configuration file (and to regenerate
297 sighup_handler(int sig)
299 int save_errno = errno;
302 signal(SIGHUP, sighup_handler);
307 * Called from the main program after receiving SIGHUP.
308 * Restarts the server.
313 logit("Received SIGHUP; restarting.");
314 close_listen_socks();
315 close_startup_pipes();
316 alarm(0); /* alarm timer persists across exec */
317 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
318 execv(saved_argv[0], saved_argv);
319 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
325 * Generic signal handler for terminating signals in the master daemon.
329 sigterm_handler(int sig)
331 received_sigterm = sig;
335 * SIGCHLD handler. This is called whenever a child dies. This will then
336 * reap any zombies left by exited children.
340 main_sigchld_handler(int sig)
342 int save_errno = errno;
346 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
347 (pid < 0 && errno == EINTR))
350 signal(SIGCHLD, main_sigchld_handler);
355 * Signal handler for the alarm after the login grace period has expired.
359 grace_alarm_handler(int sig)
361 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
362 kill(pmonitor->m_pid, SIGALRM);
364 /* Log error and exit. */
365 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
369 * Signal handler for the key regeneration alarm. Note that this
370 * alarm only occurs in the daemon waiting for connections, and it does not
371 * do anything with the private key or random state before forking.
372 * Thus there should be no concurrency control/asynchronous execution
376 generate_ephemeral_server_key(void)
378 verbose("Generating %s%d bit RSA key.",
379 sensitive_data.server_key ? "new " : "", options.server_key_bits);
380 if (sensitive_data.server_key != NULL)
381 key_free(sensitive_data.server_key);
382 sensitive_data.server_key = key_generate(KEY_RSA1,
383 options.server_key_bits);
384 verbose("RSA key generation complete.");
386 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
392 key_regeneration_alarm(int sig)
394 int save_errno = errno;
396 signal(SIGALRM, SIG_DFL);
402 sshd_exchange_identification(int sock_in, int sock_out)
406 int remote_major, remote_minor;
408 char *s, *newline = "\n";
409 char buf[256]; /* Must not be larger than remote_version. */
410 char remote_version[256]; /* Must be at least as big as buf. */
412 if ((options.protocol & SSH_PROTO_1) &&
413 (options.protocol & SSH_PROTO_2)) {
414 major = PROTOCOL_MAJOR_1;
416 } else if (options.protocol & SSH_PROTO_2) {
417 major = PROTOCOL_MAJOR_2;
418 minor = PROTOCOL_MINOR_2;
421 major = PROTOCOL_MAJOR_1;
422 minor = PROTOCOL_MINOR_1;
424 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
425 SSH_VERSION, newline);
426 server_version_string = xstrdup(buf);
428 /* Send our protocol version identification. */
429 if (roaming_atomicio(vwrite, sock_out, server_version_string,
430 strlen(server_version_string))
431 != strlen(server_version_string)) {
432 logit("Could not write ident string to %s", get_remote_ipaddr());
436 /* Read other sides version identification. */
437 memset(buf, 0, sizeof(buf));
438 for (i = 0; i < sizeof(buf) - 1; i++) {
439 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
440 logit("Did not receive identification string from %s",
441 get_remote_ipaddr());
444 if (buf[i] == '\r') {
446 /* Kludge for F-Secure Macintosh < 1.0.2 */
448 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
452 if (buf[i] == '\n') {
457 buf[sizeof(buf) - 1] = 0;
458 client_version_string = xstrdup(buf);
461 * Check that the versions match. In future this might accept
462 * several versions and set appropriate flags to handle them.
464 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
465 &remote_major, &remote_minor, remote_version) != 3) {
466 s = "Protocol mismatch.\n";
467 (void) atomicio(vwrite, sock_out, s, strlen(s));
470 logit("Bad protocol version identification '%.100s' from %s",
471 client_version_string, get_remote_ipaddr());
474 debug("Client protocol version %d.%d; client software version %.100s",
475 remote_major, remote_minor, remote_version);
477 compat_datafellows(remote_version);
479 if (datafellows & SSH_BUG_PROBE) {
480 logit("probed from %s with %s. Don't panic.",
481 get_remote_ipaddr(), client_version_string);
485 if (datafellows & SSH_BUG_SCANNER) {
486 logit("scanned from %s with %s. Don't panic.",
487 get_remote_ipaddr(), client_version_string);
492 switch (remote_major) {
494 if (remote_minor == 99) {
495 if (options.protocol & SSH_PROTO_2)
501 if (!(options.protocol & SSH_PROTO_1)) {
505 if (remote_minor < 3) {
506 packet_disconnect("Your ssh version is too old and "
507 "is no longer supported. Please install a newer version.");
508 } else if (remote_minor == 3) {
509 /* note that this disables agent-forwarding */
514 if (options.protocol & SSH_PROTO_2) {
523 chop(server_version_string);
524 debug("Local version string %.200s", server_version_string);
527 s = "Protocol major versions differ.\n";
528 (void) atomicio(vwrite, sock_out, s, strlen(s));
531 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
533 server_version_string, client_version_string);
538 /* Destroy the host and server keys. They will no longer be needed. */
540 destroy_sensitive_data(void)
544 if (sensitive_data.server_key) {
545 key_free(sensitive_data.server_key);
546 sensitive_data.server_key = NULL;
548 for (i = 0; i < options.num_host_key_files; i++) {
549 if (sensitive_data.host_keys[i]) {
550 key_free(sensitive_data.host_keys[i]);
551 sensitive_data.host_keys[i] = NULL;
553 if (sensitive_data.host_certificates[i]) {
554 key_free(sensitive_data.host_certificates[i]);
555 sensitive_data.host_certificates[i] = NULL;
558 sensitive_data.ssh1_host_key = NULL;
559 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
562 /* Demote private to public keys for network child */
564 demote_sensitive_data(void)
569 if (sensitive_data.server_key) {
570 tmp = key_demote(sensitive_data.server_key);
571 key_free(sensitive_data.server_key);
572 sensitive_data.server_key = tmp;
575 for (i = 0; i < options.num_host_key_files; i++) {
576 if (sensitive_data.host_keys[i]) {
577 tmp = key_demote(sensitive_data.host_keys[i]);
578 key_free(sensitive_data.host_keys[i]);
579 sensitive_data.host_keys[i] = tmp;
580 if (tmp->type == KEY_RSA1)
581 sensitive_data.ssh1_host_key = tmp;
583 /* Certs do not need demotion */
586 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
590 privsep_preauth_child(void)
595 /* Enable challenge-response authentication for privilege separation */
596 privsep_challenge_enable();
599 arc4random_buf(rnd, sizeof(rnd));
600 RAND_seed(rnd, sizeof(rnd));
602 /* Demote the private keys to public keys. */
603 demote_sensitive_data();
605 /* Change our root directory */
606 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
607 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
609 if (chdir("/") == -1)
610 fatal("chdir(\"/\"): %s", strerror(errno));
612 /* Drop our privileges */
613 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
614 (u_int)privsep_pw->pw_gid);
616 /* XXX not ready, too heavy after chroot */
617 do_setusercontext(privsep_pw);
619 gidset[0] = privsep_pw->pw_gid;
620 if (setgroups(1, gidset) < 0)
621 fatal("setgroups: %.100s", strerror(errno));
622 permanently_set_uid(privsep_pw);
627 privsep_preauth(Authctxt *authctxt)
632 /* Set up unprivileged child process to deal with network data */
633 pmonitor = monitor_init();
634 /* Store a pointer to the kex for later rekeying */
635 pmonitor->m_pkex = &xxx_kex;
639 fatal("fork of unprivileged child failed");
640 } else if (pid != 0) {
641 debug2("Network child is on pid %ld", (long)pid);
643 close(pmonitor->m_recvfd);
644 pmonitor->m_pid = pid;
645 monitor_child_preauth(authctxt, pmonitor);
646 close(pmonitor->m_sendfd);
649 monitor_sync(pmonitor);
651 /* Wait for the child's exit status */
652 while (waitpid(pid, &status, 0) < 0)
659 close(pmonitor->m_sendfd);
661 /* Demote the child */
662 if (getuid() == 0 || geteuid() == 0)
663 privsep_preauth_child();
664 setproctitle("%s", "[net]");
670 privsep_postauth(Authctxt *authctxt)
674 #ifdef DISABLE_FD_PASSING
677 if (authctxt->pw->pw_uid == 0 || options.use_login) {
679 /* File descriptor passing is broken or root login */
684 /* New socket pair */
685 monitor_reinit(pmonitor);
687 pmonitor->m_pid = fork();
688 if (pmonitor->m_pid == -1)
689 fatal("fork of unprivileged child failed");
690 else if (pmonitor->m_pid != 0) {
691 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
692 close(pmonitor->m_recvfd);
693 buffer_clear(&loginmsg);
694 monitor_child_postauth(pmonitor);
700 close(pmonitor->m_sendfd);
702 /* Demote the private keys to public keys. */
703 demote_sensitive_data();
706 arc4random_buf(rnd, sizeof(rnd));
707 RAND_seed(rnd, sizeof(rnd));
709 /* Drop privileges */
710 do_setusercontext(authctxt->pw);
713 /* It is safe now to apply the key state */
714 monitor_apply_keystate(pmonitor);
717 * Tell the packet layer that authentication was successful, since
718 * this information is not part of the key state.
720 packet_set_authenticated();
724 list_hostkey_types(void)
733 for (i = 0; i < options.num_host_key_files; i++) {
734 key = sensitive_data.host_keys[i];
741 if (buffer_len(&b) > 0)
742 buffer_append(&b, ",", 1);
743 p = key_ssh_name(key);
744 buffer_append(&b, p, strlen(p));
747 /* If the private key has a cert peer, then list that too */
748 key = sensitive_data.host_certificates[i];
752 case KEY_RSA_CERT_V00:
753 case KEY_DSA_CERT_V00:
757 if (buffer_len(&b) > 0)
758 buffer_append(&b, ",", 1);
759 p = key_ssh_name(key);
760 buffer_append(&b, p, strlen(p));
764 buffer_append(&b, "\0", 1);
765 ret = xstrdup(buffer_ptr(&b));
767 debug("list_hostkey_types: %s", ret);
772 get_hostkey_by_type(int type, int need_private)
777 for (i = 0; i < options.num_host_key_files; i++) {
779 case KEY_RSA_CERT_V00:
780 case KEY_DSA_CERT_V00:
784 key = sensitive_data.host_certificates[i];
787 key = sensitive_data.host_keys[i];
790 if (key != NULL && key->type == type)
791 return need_private ?
792 sensitive_data.host_keys[i] : key;
798 get_hostkey_public_by_type(int type)
800 return get_hostkey_by_type(type, 0);
804 get_hostkey_private_by_type(int type)
806 return get_hostkey_by_type(type, 1);
810 get_hostkey_by_index(int ind)
812 if (ind < 0 || ind >= options.num_host_key_files)
814 return (sensitive_data.host_keys[ind]);
818 get_hostkey_index(Key *key)
822 for (i = 0; i < options.num_host_key_files; i++) {
823 if (key_is_cert(key)) {
824 if (key == sensitive_data.host_certificates[i])
827 if (key == sensitive_data.host_keys[i])
835 * returns 1 if connection should be dropped, 0 otherwise.
836 * dropping starts at connection #max_startups_begin with a probability
837 * of (max_startups_rate/100). the probability increases linearly until
838 * all connections are dropped for startups > max_startups
841 drop_connection(int startups)
845 if (startups < options.max_startups_begin)
847 if (startups >= options.max_startups)
849 if (options.max_startups_rate == 100)
852 p = 100 - options.max_startups_rate;
853 p *= startups - options.max_startups_begin;
854 p /= options.max_startups - options.max_startups_begin;
855 p += options.max_startups_rate;
856 r = arc4random_uniform(100);
858 debug("drop_connection: p %d, r %d", p, r);
859 return (r < p) ? 1 : 0;
865 fprintf(stderr, "%s, %s\n",
866 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
868 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
869 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
870 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
876 send_rexec_state(int fd, Buffer *conf)
880 debug3("%s: entering fd = %d config len %d", __func__, fd,
884 * Protocol from reexec master to child:
885 * string configuration
886 * u_int ephemeral_key_follows
887 * bignum e (only if ephemeral_key_follows == 1)
893 * string rngseed (only if OpenSSL is not self-seeded)
896 buffer_put_cstring(&m, buffer_ptr(conf));
898 if (sensitive_data.server_key != NULL &&
899 sensitive_data.server_key->type == KEY_RSA1) {
900 buffer_put_int(&m, 1);
901 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
902 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
903 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
904 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
905 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
906 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
908 buffer_put_int(&m, 0);
910 #ifndef OPENSSL_PRNG_ONLY
911 rexec_send_rng_seed(&m);
914 if (ssh_msg_send(fd, 0, &m) == -1)
915 fatal("%s: ssh_msg_send failed", __func__);
919 debug3("%s: done", __func__);
923 recv_rexec_state(int fd, Buffer *conf)
929 debug3("%s: entering fd = %d", __func__, fd);
933 if (ssh_msg_recv(fd, &m) == -1)
934 fatal("%s: ssh_msg_recv failed", __func__);
935 if (buffer_get_char(&m) != 0)
936 fatal("%s: rexec version mismatch", __func__);
938 cp = buffer_get_string(&m, &len);
940 buffer_append(conf, cp, len + 1);
943 if (buffer_get_int(&m)) {
944 if (sensitive_data.server_key != NULL)
945 key_free(sensitive_data.server_key);
946 sensitive_data.server_key = key_new_private(KEY_RSA1);
947 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
948 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
949 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
950 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
951 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
952 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
953 rsa_generate_additional_parameters(
954 sensitive_data.server_key->rsa);
957 #ifndef OPENSSL_PRNG_ONLY
958 rexec_recv_rng_seed(&m);
963 debug3("%s: done", __func__);
966 /* Accept a connection from inetd */
968 server_accept_inetd(int *sock_in, int *sock_out)
974 close(REEXEC_CONFIG_PASS_FD);
975 *sock_in = *sock_out = dup(STDIN_FILENO);
977 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
978 close(REEXEC_STARTUP_PIPE_FD);
981 *sock_in = dup(STDIN_FILENO);
982 *sock_out = dup(STDOUT_FILENO);
985 * We intentionally do not close the descriptors 0, 1, and 2
986 * as our code for setting the descriptors won't work if
987 * ttyfd happens to be one of those.
989 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
990 dup2(fd, STDIN_FILENO);
991 dup2(fd, STDOUT_FILENO);
992 if (fd > STDOUT_FILENO)
995 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
999 * Listen for TCP connections
1004 int ret, listen_sock, on = 1;
1005 struct addrinfo *ai;
1006 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1008 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1009 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1011 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1012 fatal("Too many listen sockets. "
1013 "Enlarge MAX_LISTEN_SOCKS");
1014 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1015 ntop, sizeof(ntop), strport, sizeof(strport),
1016 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1017 error("getnameinfo failed: %.100s",
1018 ssh_gai_strerror(ret));
1021 /* Create socket for listening. */
1022 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1024 if (listen_sock < 0) {
1025 /* kernel may not support ipv6 */
1026 verbose("socket: %.100s", strerror(errno));
1029 if (set_nonblock(listen_sock) == -1) {
1034 * Set socket options.
1035 * Allow local port reuse in TIME_WAIT.
1037 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1038 &on, sizeof(on)) == -1)
1039 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1041 /* Only communicate in IPv6 over AF_INET6 sockets. */
1042 if (ai->ai_family == AF_INET6)
1043 sock_set_v6only(listen_sock);
1045 debug("Bind to port %s on %s.", strport, ntop);
1047 /* Bind the socket to the desired port. */
1048 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1049 error("Bind to port %s on %s failed: %.200s.",
1050 strport, ntop, strerror(errno));
1054 listen_socks[num_listen_socks] = listen_sock;
1057 /* Start listening on the port. */
1058 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1059 fatal("listen on [%s]:%s: %.100s",
1060 ntop, strport, strerror(errno));
1061 logit("Server listening on %s port %s.", ntop, strport);
1063 freeaddrinfo(options.listen_addrs);
1065 if (!num_listen_socks)
1066 fatal("Cannot bind any address.");
1070 * The main TCP accept loop. Note that, for the non-debug case, returns
1071 * from this function are in a forked subprocess.
1074 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1077 int i, j, ret, maxfd;
1078 int key_used = 0, startups = 0;
1079 int startup_p[2] = { -1 , -1 };
1080 struct sockaddr_storage from;
1084 /* setup fd set for accept */
1087 for (i = 0; i < num_listen_socks; i++)
1088 if (listen_socks[i] > maxfd)
1089 maxfd = listen_socks[i];
1090 /* pipes connected to unauthenticated childs */
1091 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1092 for (i = 0; i < options.max_startups; i++)
1093 startup_pipes[i] = -1;
1096 * Stay listening for connections until the system crashes or
1097 * the daemon is killed with a signal.
1100 if (received_sighup)
1104 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1107 for (i = 0; i < num_listen_socks; i++)
1108 FD_SET(listen_socks[i], fdset);
1109 for (i = 0; i < options.max_startups; i++)
1110 if (startup_pipes[i] != -1)
1111 FD_SET(startup_pipes[i], fdset);
1113 /* Wait in select until there is a connection. */
1114 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1115 if (ret < 0 && errno != EINTR)
1116 error("select: %.100s", strerror(errno));
1117 if (received_sigterm) {
1118 logit("Received signal %d; terminating.",
1119 (int) received_sigterm);
1120 close_listen_socks();
1121 unlink(options.pid_file);
1124 if (key_used && key_do_regen) {
1125 generate_ephemeral_server_key();
1132 for (i = 0; i < options.max_startups; i++)
1133 if (startup_pipes[i] != -1 &&
1134 FD_ISSET(startup_pipes[i], fdset)) {
1136 * the read end of the pipe is ready
1137 * if the child has closed the pipe
1138 * after successful authentication
1139 * or if the child has died
1141 close(startup_pipes[i]);
1142 startup_pipes[i] = -1;
1145 for (i = 0; i < num_listen_socks; i++) {
1146 if (!FD_ISSET(listen_socks[i], fdset))
1148 fromlen = sizeof(from);
1149 *newsock = accept(listen_socks[i],
1150 (struct sockaddr *)&from, &fromlen);
1152 if (errno != EINTR && errno != EAGAIN &&
1153 errno != EWOULDBLOCK)
1154 error("accept: %.100s", strerror(errno));
1157 if (unset_nonblock(*newsock) == -1) {
1161 if (drop_connection(startups) == 1) {
1162 debug("drop connection #%d", startups);
1166 if (pipe(startup_p) == -1) {
1171 if (rexec_flag && socketpair(AF_UNIX,
1172 SOCK_STREAM, 0, config_s) == -1) {
1173 error("reexec socketpair: %s",
1176 close(startup_p[0]);
1177 close(startup_p[1]);
1181 for (j = 0; j < options.max_startups; j++)
1182 if (startup_pipes[j] == -1) {
1183 startup_pipes[j] = startup_p[0];
1184 if (maxfd < startup_p[0])
1185 maxfd = startup_p[0];
1191 * Got connection. Fork a child to handle it, unless
1192 * we are in debugging mode.
1196 * In debugging mode. Close the listening
1197 * socket, and start processing the
1198 * connection without forking.
1200 debug("Server will not fork when running in debugging mode.");
1201 close_listen_socks();
1202 *sock_in = *newsock;
1203 *sock_out = *newsock;
1204 close(startup_p[0]);
1205 close(startup_p[1]);
1209 send_rexec_state(config_s[0],
1217 * Normal production daemon. Fork, and have
1218 * the child process the connection. The
1219 * parent continues listening.
1221 platform_pre_fork();
1222 if ((pid = fork()) == 0) {
1224 * Child. Close the listening and
1225 * max_startup sockets. Start using
1226 * the accepted socket. Reinitialize
1227 * logging (since our pid has changed).
1228 * We break out of the loop to handle
1231 platform_post_fork_child();
1232 startup_pipe = startup_p[1];
1233 close_startup_pipes();
1234 close_listen_socks();
1235 *sock_in = *newsock;
1236 *sock_out = *newsock;
1237 log_init(__progname,
1239 options.log_facility,
1246 /* Parent. Stay in the loop. */
1247 platform_post_fork_parent(pid);
1249 error("fork: %.100s", strerror(errno));
1251 debug("Forked child %ld.", (long)pid);
1253 close(startup_p[1]);
1256 send_rexec_state(config_s[0], &cfg);
1262 * Mark that the key has been used (it
1263 * was "given" to the child).
1265 if ((options.protocol & SSH_PROTO_1) &&
1267 /* Schedule server key regeneration alarm. */
1268 signal(SIGALRM, key_regeneration_alarm);
1269 alarm(options.key_regeneration_time);
1276 * Ensure that our random state differs
1277 * from that of the child
1282 /* child process check (or debug mode) */
1283 if (num_listen_socks < 0)
1290 * Main program for the daemon.
1293 main(int ac, char **av)
1295 extern char *optarg;
1297 int opt, i, j, on = 1;
1298 int sock_in = -1, sock_out = -1, newsock = -1;
1299 const char *remote_ip;
1300 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1302 char *line, *p, *cp;
1303 int config_s[2] = { -1 , -1 };
1304 u_int64_t ibytes, obytes;
1309 #ifdef HAVE_SECUREWARE
1310 (void)set_auth_parameters(ac, av);
1312 __progname = ssh_get_progname(av[0]);
1315 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1318 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1319 for (i = 0; i < ac; i++)
1320 saved_argv[i] = xstrdup(av[i]);
1321 saved_argv[i] = NULL;
1323 #ifndef HAVE_SETPROCTITLE
1324 /* Prepare for later setproctitle emulation */
1325 compat_init_setproctitle(ac, av);
1329 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1330 debug("setgroups(): %.200s", strerror(errno));
1332 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1335 /* Initialize configuration options to their default values. */
1336 initialize_server_options(&options);
1338 /* Parse command-line arguments. */
1339 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1342 options.address_family = AF_INET;
1345 options.address_family = AF_INET6;
1348 config_file_name = optarg;
1351 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1352 fprintf(stderr, "too many host certificates.\n");
1355 options.host_cert_files[options.num_host_cert_files++] =
1356 derelativise_path(optarg);
1359 if (debug_flag == 0) {
1361 options.log_level = SYSLOG_LEVEL_DEBUG1;
1362 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1363 options.log_level++;
1385 options.log_level = SYSLOG_LEVEL_QUIET;
1388 options.server_key_bits = (int)strtonum(optarg, 256,
1392 options.ports_from_cmdline = 1;
1393 if (options.num_ports >= MAX_PORTS) {
1394 fprintf(stderr, "too many ports.\n");
1397 options.ports[options.num_ports++] = a2port(optarg);
1398 if (options.ports[options.num_ports-1] <= 0) {
1399 fprintf(stderr, "Bad port number.\n");
1404 if ((options.login_grace_time = convtime(optarg)) == -1) {
1405 fprintf(stderr, "Invalid login grace time.\n");
1410 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1411 fprintf(stderr, "Invalid key regeneration interval.\n");
1416 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1417 fprintf(stderr, "too many host keys.\n");
1420 options.host_key_files[options.num_host_key_files++] =
1421 derelativise_path(optarg);
1431 while ((p = strsep(&cp, ",")) && *p != '\0') {
1432 if (strncmp(p, "addr=", 5) == 0)
1433 test_addr = xstrdup(p + 5);
1434 else if (strncmp(p, "host=", 5) == 0)
1435 test_host = xstrdup(p + 5);
1436 else if (strncmp(p, "user=", 5) == 0)
1437 test_user = xstrdup(p + 5);
1439 fprintf(stderr, "Invalid test "
1440 "mode specification %s\n", p);
1446 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1447 if (utmp_len > MAXHOSTNAMELEN) {
1448 fprintf(stderr, "Invalid utmp length.\n");
1453 line = xstrdup(optarg);
1454 if (process_server_config_line(&options, line,
1455 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1465 if (rexeced_flag || inetd_flag)
1467 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1468 fatal("sshd re-exec requires execution with an absolute path");
1470 closefrom(REEXEC_MIN_FREE_FD);
1472 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1474 OpenSSL_add_all_algorithms();
1477 * Force logging to stderr until we have loaded the private host
1478 * key (unless started from inetd)
1480 log_init(__progname,
1481 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1482 SYSLOG_LEVEL_INFO : options.log_level,
1483 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1484 SYSLOG_FACILITY_AUTH : options.log_facility,
1485 log_stderr || !inetd_flag);
1488 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1489 * root's environment
1491 if (getenv("KRB5CCNAME") != NULL)
1492 unsetenv("KRB5CCNAME");
1495 /* Cray can define user privs drop all privs now!
1496 * Not needed on PRIV_SU systems!
1501 sensitive_data.server_key = NULL;
1502 sensitive_data.ssh1_host_key = NULL;
1503 sensitive_data.have_ssh1_key = 0;
1504 sensitive_data.have_ssh2_key = 0;
1507 * If we're doing an extended config test, make sure we have all of
1508 * the parameters we need. If we're not doing an extended test,
1509 * do not silently ignore connection test params.
1511 if (test_flag >= 2 &&
1512 (test_user != NULL || test_host != NULL || test_addr != NULL)
1513 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1514 fatal("user, host and addr are all required when testing "
1516 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1518 fatal("Config test connection parameter (-C) provided without "
1521 /* Fetch our configuration */
1524 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1526 load_server_config(config_file_name, &cfg);
1528 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1529 &cfg, NULL, NULL, NULL);
1533 /* Fill in default values for those options not explicitly set. */
1534 fill_default_server_options(&options);
1536 /* challenge-response is implemented via keyboard interactive */
1537 if (options.challenge_response_authentication)
1538 options.kbd_interactive_authentication = 1;
1540 /* set default channel AF */
1541 channel_set_af(options.address_family);
1543 /* Check that there are no remaining arguments. */
1545 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1549 debug("sshd version %.100s", SSH_RELEASE);
1551 /* Store privilege separation user for later use if required. */
1552 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1553 if (use_privsep || options.kerberos_authentication)
1554 fatal("Privilege separation user %s does not exist",
1557 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1558 privsep_pw = pwcopy(privsep_pw);
1559 xfree(privsep_pw->pw_passwd);
1560 privsep_pw->pw_passwd = xstrdup("*");
1564 /* load private host keys */
1565 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1567 for (i = 0; i < options.num_host_key_files; i++)
1568 sensitive_data.host_keys[i] = NULL;
1570 for (i = 0; i < options.num_host_key_files; i++) {
1571 key = key_load_private(options.host_key_files[i], "", NULL);
1572 sensitive_data.host_keys[i] = key;
1574 error("Could not load host key: %s",
1575 options.host_key_files[i]);
1576 sensitive_data.host_keys[i] = NULL;
1579 switch (key->type) {
1581 sensitive_data.ssh1_host_key = key;
1582 sensitive_data.have_ssh1_key = 1;
1587 sensitive_data.have_ssh2_key = 1;
1590 debug("private host key: #%d type %d %s", i, key->type,
1593 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1594 logit("Disabling protocol version 1. Could not load host key");
1595 options.protocol &= ~SSH_PROTO_1;
1598 /* The GSSAPI key exchange can run without a host key */
1599 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1600 logit("Disabling protocol version 2. Could not load host key");
1601 options.protocol &= ~SSH_PROTO_2;
1604 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1605 logit("sshd: no hostkeys available -- exiting.");
1610 * Load certificates. They are stored in an array at identical
1611 * indices to the public keys that they relate to.
1613 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1615 for (i = 0; i < options.num_host_key_files; i++)
1616 sensitive_data.host_certificates[i] = NULL;
1618 for (i = 0; i < options.num_host_cert_files; i++) {
1619 key = key_load_public(options.host_cert_files[i], NULL);
1621 error("Could not load host certificate: %s",
1622 options.host_cert_files[i]);
1625 if (!key_is_cert(key)) {
1626 error("Certificate file is not a certificate: %s",
1627 options.host_cert_files[i]);
1631 /* Find matching private key */
1632 for (j = 0; j < options.num_host_key_files; j++) {
1633 if (key_equal_public(key,
1634 sensitive_data.host_keys[j])) {
1635 sensitive_data.host_certificates[j] = key;
1639 if (j >= options.num_host_key_files) {
1640 error("No matching private key for certificate: %s",
1641 options.host_cert_files[i]);
1645 sensitive_data.host_certificates[j] = key;
1646 debug("host certificate: #%d type %d %s", j, key->type,
1649 /* Check certain values for sanity. */
1650 if (options.protocol & SSH_PROTO_1) {
1651 if (options.server_key_bits < 512 ||
1652 options.server_key_bits > 32768) {
1653 fprintf(stderr, "Bad server key size.\n");
1657 * Check that server and host key lengths differ sufficiently. This
1658 * is necessary to make double encryption work with rsaref. Oh, I
1659 * hate software patents. I dont know if this can go? Niels
1661 if (options.server_key_bits >
1662 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1663 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1664 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1665 SSH_KEY_BITS_RESERVED) {
1666 options.server_key_bits =
1667 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1668 SSH_KEY_BITS_RESERVED;
1669 debug("Forcing server key to %d bits to make it differ from host key.",
1670 options.server_key_bits);
1677 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1678 (S_ISDIR(st.st_mode) == 0))
1679 fatal("Missing privilege separation directory: %s",
1680 _PATH_PRIVSEP_CHROOT_DIR);
1683 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1684 (st.st_uid != getuid () ||
1685 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1687 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1689 fatal("%s must be owned by root and not group or "
1690 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1693 if (test_flag > 1) {
1694 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1695 parse_server_match_config(&options, test_user,
1696 test_host, test_addr);
1697 dump_config(&options);
1700 /* Configuration looks good, so exit if in test mode. */
1705 * Clear out any supplemental groups we may have inherited. This
1706 * prevents inadvertent creation of files with bad modes (in the
1707 * portable version at least, it's certainly possible for PAM
1708 * to create a file, and we can't control the code in every
1709 * module which might be used).
1711 if (setgroups(0, NULL) < 0)
1712 debug("setgroups() failed: %.200s", strerror(errno));
1715 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1716 for (i = 0; i < rexec_argc; i++) {
1717 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1718 rexec_argv[i] = saved_argv[i];
1720 rexec_argv[rexec_argc] = "-R";
1721 rexec_argv[rexec_argc + 1] = NULL;
1724 /* Ensure that umask disallows at least group and world write */
1725 new_umask = umask(0077) | 0022;
1726 (void) umask(new_umask);
1728 /* Initialize the log (it is reinitialized below in case we forked). */
1729 if (debug_flag && (!inetd_flag || rexeced_flag))
1731 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1734 * If not in debugging mode, and not started from inetd, disconnect
1735 * from the controlling terminal, and fork. The original process
1738 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1741 #endif /* TIOCNOTTY */
1742 if (daemon(0, 0) < 0)
1743 fatal("daemon() failed: %.200s", strerror(errno));
1745 /* Disconnect from the controlling tty. */
1747 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1749 (void) ioctl(fd, TIOCNOTTY, NULL);
1752 #endif /* TIOCNOTTY */
1754 /* Reinitialize the log (because of the fork above). */
1755 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1757 /* Initialize the random number generator. */
1760 /* Chdir to the root directory so that the current disk can be
1761 unmounted if desired. */
1764 /* ignore SIGPIPE */
1765 signal(SIGPIPE, SIG_IGN);
1767 /* Get a connection, either from inetd or a listening TCP socket */
1769 server_accept_inetd(&sock_in, &sock_out);
1771 platform_pre_listen();
1774 if (options.protocol & SSH_PROTO_1)
1775 generate_ephemeral_server_key();
1777 signal(SIGHUP, sighup_handler);
1778 signal(SIGCHLD, main_sigchld_handler);
1779 signal(SIGTERM, sigterm_handler);
1780 signal(SIGQUIT, sigterm_handler);
1783 * Write out the pid file after the sigterm handler
1784 * is setup and the listen sockets are bound
1787 FILE *f = fopen(options.pid_file, "w");
1790 error("Couldn't create pid file \"%s\": %s",
1791 options.pid_file, strerror(errno));
1793 fprintf(f, "%ld\n", (long) getpid());
1798 /* Accept a connection and return in a forked child */
1799 server_accept_loop(&sock_in, &sock_out,
1800 &newsock, config_s);
1803 /* This is the child processing a new connection. */
1804 setproctitle("%s", "[accepted]");
1807 * Create a new session and process group since the 4.4BSD
1808 * setlogin() affects the entire process group. We don't
1809 * want the child to be able to affect the parent.
1811 #if !defined(SSHD_ACQUIRES_CTTY)
1813 * If setsid is called, on some platforms sshd will later acquire a
1814 * controlling terminal which will result in "could not set
1815 * controlling tty" errors.
1817 if (!debug_flag && !inetd_flag && setsid() < 0)
1818 error("setsid: %.100s", strerror(errno));
1824 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1825 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1826 dup2(newsock, STDIN_FILENO);
1827 dup2(STDIN_FILENO, STDOUT_FILENO);
1828 if (startup_pipe == -1)
1829 close(REEXEC_STARTUP_PIPE_FD);
1831 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1833 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1835 if (startup_pipe != -1)
1836 close(startup_pipe);
1838 execv(rexec_argv[0], rexec_argv);
1840 /* Reexec has failed, fall back and continue */
1841 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1842 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1843 log_init(__progname, options.log_level,
1844 options.log_facility, log_stderr);
1847 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1849 close(REEXEC_CONFIG_PASS_FD);
1850 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1851 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1852 dup2(fd, STDIN_FILENO);
1853 dup2(fd, STDOUT_FILENO);
1854 if (fd > STDERR_FILENO)
1857 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1858 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1861 /* Executed child processes don't need these. */
1862 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1863 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1866 * Disable the key regeneration alarm. We will not regenerate the
1867 * key since we are no longer in a position to give it to anyone. We
1868 * will not restart on SIGHUP since it no longer makes sense.
1871 signal(SIGALRM, SIG_DFL);
1872 signal(SIGHUP, SIG_DFL);
1873 signal(SIGTERM, SIG_DFL);
1874 signal(SIGQUIT, SIG_DFL);
1875 signal(SIGCHLD, SIG_DFL);
1876 signal(SIGINT, SIG_DFL);
1879 * Register our connection. This turns encryption off because we do
1882 packet_set_connection(sock_in, sock_out);
1883 packet_set_server();
1885 /* Set SO_KEEPALIVE if requested. */
1886 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1887 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1888 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1890 if ((remote_port = get_remote_port()) < 0) {
1891 debug("get_remote_port failed");
1896 * We use get_canonical_hostname with usedns = 0 instead of
1897 * get_remote_ipaddr here so IP options will be checked.
1899 (void) get_canonical_hostname(0);
1901 * The rest of the code depends on the fact that
1902 * get_remote_ipaddr() caches the remote ip, even if
1903 * the socket goes away.
1905 remote_ip = get_remote_ipaddr();
1907 #ifdef SSH_AUDIT_EVENTS
1908 audit_connection_from(remote_ip, remote_port);
1911 allow_severity = options.log_facility|LOG_INFO;
1912 deny_severity = options.log_facility|LOG_WARNING;
1913 /* Check whether logins are denied from this host. */
1914 if (packet_connection_is_on_socket()) {
1915 struct request_info req;
1917 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1920 if (!hosts_access(&req)) {
1921 debug("Connection refused by tcp wrapper");
1924 fatal("libwrap refuse returns");
1927 #endif /* LIBWRAP */
1929 /* Log the connection. */
1930 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1932 #ifdef USE_SECURITY_SESSION_API
1934 * Create a new security session for use by the new user login if
1935 * the current session is the root session or we are not launched
1936 * by inetd (eg: debugging mode or server mode). We do not
1937 * necessarily need to create a session if we are launched from
1938 * inetd because Panther xinetd will create a session for us.
1940 * The only case where this logic will fail is if there is an
1941 * inetd running in a non-root session which is not creating
1942 * new sessions for us. Then all the users will end up in the
1943 * same session (bad).
1945 * When the client exits, the session will be destroyed for us
1948 * We must create the session before any credentials are stored
1949 * (including AFS pags, which happens a few lines below).
1953 SecuritySessionId sid = 0;
1954 SessionAttributeBits sattrs = 0;
1956 err = SessionGetInfo(callerSecuritySession, &sid, &sattrs);
1958 error("SessionGetInfo() failed with error %.8X",
1961 debug("Current Session ID is %.8X / Session Attributes are %.8X",
1962 (unsigned) sid, (unsigned) sattrs);
1964 if (inetd_flag && !(sattrs & sessionIsRoot))
1965 debug("Running in inetd mode in a non-root session... "
1966 "assuming inetd created the session for us.");
1968 debug("Creating new security session...");
1969 err = SessionCreate(0, sessionHasTTY | sessionIsRemote);
1971 error("SessionCreate() failed with error %.8X",
1974 err = SessionGetInfo(callerSecuritySession, &sid,
1977 error("SessionGetInfo() failed with error %.8X",
1980 debug("New Session ID is %.8X / Session Attributes are %.8X",
1981 (unsigned) sid, (unsigned) sattrs);
1987 * We don't want to listen forever unless the other side
1988 * successfully authenticates itself. So we set up an alarm which is
1989 * cleared after successful authentication. A limit of zero
1990 * indicates no limit. Note that we don't set the alarm in debugging
1991 * mode; it is just annoying to have the server exit just when you
1992 * are about to discover the bug.
1994 signal(SIGALRM, grace_alarm_handler);
1996 alarm(options.login_grace_time);
1998 sshd_exchange_identification(sock_in, sock_out);
2000 /* In inetd mode, generate ephemeral key only for proto 1 connections */
2001 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
2002 generate_ephemeral_server_key();
2004 packet_set_nonblocking();
2006 /* allocate authentication context */
2007 authctxt = xcalloc(1, sizeof(*authctxt));
2009 authctxt->loginmsg = &loginmsg;
2011 /* XXX global for cleanup, access from other modules */
2012 the_authctxt = authctxt;
2014 /* prepare buffer to collect messages to display to user after login */
2015 buffer_init(&loginmsg);
2019 if (privsep_preauth(authctxt) == 1)
2022 /* perform the key exchange */
2023 /* authenticate user and start session */
2026 do_authentication2(authctxt);
2029 do_authentication(authctxt);
2032 * If we use privilege separation, the unprivileged child transfers
2033 * the current keystate and exits
2036 mm_send_keystate(pmonitor);
2042 * Cancel the alarm we set to limit the time taken for
2046 signal(SIGALRM, SIG_DFL);
2047 authctxt->authenticated = 1;
2048 if (startup_pipe != -1) {
2049 close(startup_pipe);
2053 #ifdef SSH_AUDIT_EVENTS
2054 audit_event(SSH_AUTH_SUCCESS);
2058 if (options.gss_authentication) {
2059 temporarily_use_uid(authctxt->pw);
2060 ssh_gssapi_storecreds();
2065 if (options.use_pam) {
2072 * In privilege separation, we fork another child and prepare
2073 * file descriptor passing.
2076 privsep_postauth(authctxt);
2077 /* the monitor process [priv] will not return */
2079 destroy_sensitive_data();
2082 packet_set_timeout(options.client_alive_interval,
2083 options.client_alive_count_max);
2085 /* Start session. */
2086 do_authenticated(authctxt);
2088 /* The connection has been terminated. */
2089 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2090 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2091 verbose("Transferred: sent %llu, received %llu bytes",
2092 (unsigned long long)obytes, (unsigned long long)ibytes);
2094 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2097 if (options.use_pam)
2099 #endif /* USE_PAM */
2101 #ifdef SSH_AUDIT_EVENTS
2102 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2114 * Decrypt session_key_int using our private server key and private host key
2115 * (key with larger modulus first).
2118 ssh1_session_key(BIGNUM *session_key_int)
2122 if (BN_cmp(sensitive_data.server_key->rsa->n,
2123 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2124 /* Server key has bigger modulus. */
2125 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2126 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2127 SSH_KEY_BITS_RESERVED) {
2128 fatal("do_connection: %s: "
2129 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2130 get_remote_ipaddr(),
2131 BN_num_bits(sensitive_data.server_key->rsa->n),
2132 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2133 SSH_KEY_BITS_RESERVED);
2135 if (rsa_private_decrypt(session_key_int, session_key_int,
2136 sensitive_data.server_key->rsa) <= 0)
2138 if (rsa_private_decrypt(session_key_int, session_key_int,
2139 sensitive_data.ssh1_host_key->rsa) <= 0)
2142 /* Host key has bigger modulus (or they are equal). */
2143 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2144 BN_num_bits(sensitive_data.server_key->rsa->n) +
2145 SSH_KEY_BITS_RESERVED) {
2146 fatal("do_connection: %s: "
2147 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2148 get_remote_ipaddr(),
2149 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2150 BN_num_bits(sensitive_data.server_key->rsa->n),
2151 SSH_KEY_BITS_RESERVED);
2153 if (rsa_private_decrypt(session_key_int, session_key_int,
2154 sensitive_data.ssh1_host_key->rsa) < 0)
2156 if (rsa_private_decrypt(session_key_int, session_key_int,
2157 sensitive_data.server_key->rsa) < 0)
2170 BIGNUM *session_key_int;
2171 u_char session_key[SSH_SESSION_KEY_LENGTH];
2173 u_int cipher_type, auth_mask, protocol_flags;
2176 * Generate check bytes that the client must send back in the user
2177 * packet in order for it to be accepted; this is used to defy ip
2178 * spoofing attacks. Note that this only works against somebody
2179 * doing IP spoofing from a remote machine; any machine on the local
2180 * network can still see outgoing packets and catch the random
2181 * cookie. This only affects rhosts authentication, and this is one
2182 * of the reasons why it is inherently insecure.
2184 arc4random_buf(cookie, sizeof(cookie));
2187 * Send our public key. We include in the packet 64 bits of random
2188 * data that must be matched in the reply in order to prevent IP
2191 packet_start(SSH_SMSG_PUBLIC_KEY);
2192 for (i = 0; i < 8; i++)
2193 packet_put_char(cookie[i]);
2195 /* Store our public server RSA key. */
2196 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2197 packet_put_bignum(sensitive_data.server_key->rsa->e);
2198 packet_put_bignum(sensitive_data.server_key->rsa->n);
2200 /* Store our public host RSA key. */
2201 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2202 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2203 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2205 /* Put protocol flags. */
2206 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2208 /* Declare which ciphers we support. */
2209 packet_put_int(cipher_mask_ssh1(0));
2211 /* Declare supported authentication types. */
2213 if (options.rhosts_rsa_authentication)
2214 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2215 if (options.rsa_authentication)
2216 auth_mask |= 1 << SSH_AUTH_RSA;
2217 if (options.challenge_response_authentication == 1)
2218 auth_mask |= 1 << SSH_AUTH_TIS;
2219 if (options.password_authentication)
2220 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2221 packet_put_int(auth_mask);
2223 /* Send the packet and wait for it to be sent. */
2225 packet_write_wait();
2227 debug("Sent %d bit server key and %d bit host key.",
2228 BN_num_bits(sensitive_data.server_key->rsa->n),
2229 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2231 /* Read clients reply (cipher type and session key). */
2232 packet_read_expect(SSH_CMSG_SESSION_KEY);
2234 /* Get cipher type and check whether we accept this. */
2235 cipher_type = packet_get_char();
2237 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2238 packet_disconnect("Warning: client selects unsupported cipher.");
2240 /* Get check bytes from the packet. These must match those we
2241 sent earlier with the public key packet. */
2242 for (i = 0; i < 8; i++)
2243 if (cookie[i] != packet_get_char())
2244 packet_disconnect("IP Spoofing check bytes do not match.");
2246 debug("Encryption type: %.200s", cipher_name(cipher_type));
2248 /* Get the encrypted integer. */
2249 if ((session_key_int = BN_new()) == NULL)
2250 fatal("do_ssh1_kex: BN_new failed");
2251 packet_get_bignum(session_key_int);
2253 protocol_flags = packet_get_int();
2254 packet_set_protocol_flags(protocol_flags);
2257 /* Decrypt session_key_int using host/server keys */
2258 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2261 * Extract session key from the decrypted integer. The key is in the
2262 * least significant 256 bits of the integer; the first byte of the
2263 * key is in the highest bits.
2266 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2267 len = BN_num_bytes(session_key_int);
2268 if (len < 0 || (u_int)len > sizeof(session_key)) {
2269 error("do_ssh1_kex: bad session key len from %s: "
2270 "session_key_int %d > sizeof(session_key) %lu",
2271 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2274 memset(session_key, 0, sizeof(session_key));
2275 BN_bn2bin(session_key_int,
2276 session_key + sizeof(session_key) - len);
2278 derive_ssh1_session_id(
2279 sensitive_data.ssh1_host_key->rsa->n,
2280 sensitive_data.server_key->rsa->n,
2281 cookie, session_id);
2283 * Xor the first 16 bytes of the session key with the
2286 for (i = 0; i < 16; i++)
2287 session_key[i] ^= session_id[i];
2291 int bytes = BN_num_bytes(session_key_int);
2292 u_char *buf = xmalloc(bytes);
2295 logit("do_connection: generating a fake encryption key");
2296 BN_bn2bin(session_key_int, buf);
2298 MD5_Update(&md, buf, bytes);
2299 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2300 MD5_Final(session_key, &md);
2302 MD5_Update(&md, session_key, 16);
2303 MD5_Update(&md, buf, bytes);
2304 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2305 MD5_Final(session_key + 16, &md);
2306 memset(buf, 0, bytes);
2308 for (i = 0; i < 16; i++)
2309 session_id[i] = session_key[i] ^ session_key[i + 16];
2311 /* Destroy the private and public keys. No longer. */
2312 destroy_sensitive_data();
2315 mm_ssh1_session_id(session_id);
2317 /* Destroy the decrypted integer. It is no longer needed. */
2318 BN_clear_free(session_key_int);
2320 /* Set the session key. From this on all communications will be encrypted. */
2321 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2323 /* Destroy our copy of the session key. It is no longer needed. */
2324 memset(session_key, 0, sizeof(session_key));
2326 debug("Received session key; encryption turned on.");
2328 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2329 packet_start(SSH_SMSG_SUCCESS);
2331 packet_write_wait();
2335 * SSH2 key exchange: diffie-hellman-group1-sha1
2342 if (options.ciphers != NULL) {
2343 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2344 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2346 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2347 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2348 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2349 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2351 if (options.macs != NULL) {
2352 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2353 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2355 if (options.compression == COMP_NONE) {
2356 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2357 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2358 } else if (options.compression == COMP_DELAYED) {
2359 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2360 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2362 if (options.kex_algorithms != NULL)
2363 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
2365 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2371 char *newstr = NULL;
2372 orig = myproposal[PROPOSAL_KEX_ALGS];
2375 * If we don't have a host key, then there's no point advertising
2376 * the other key exchange algorithms
2379 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
2382 if (options.gss_keyex)
2383 gss = ssh_gssapi_server_mechanisms();
2388 xasprintf(&newstr, "%s,%s", gss, orig);
2395 * If we've got GSSAPI mechanisms, then we've got the 'null' host
2396 * key alg, but we can't tell people about it unless its the only
2397 * host key algorithm we support
2399 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
2400 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
2403 myproposal[PROPOSAL_KEX_ALGS] = newstr;
2405 fatal("No supported key exchange algorithms");
2409 /* start key exchange */
2410 kex = kex_setup(myproposal);
2411 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2412 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2413 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2414 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2415 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2417 if (options.gss_keyex) {
2418 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
2419 kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
2420 kex->kex[KEX_GSS_GEX_SHA1] = kexgss_server;
2424 kex->client_version_string=client_version_string;
2425 kex->server_version_string=server_version_string;
2426 kex->load_host_public_key=&get_hostkey_public_by_type;
2427 kex->load_host_private_key=&get_hostkey_private_by_type;
2428 kex->host_key_index=&get_hostkey_index;
2432 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2434 session_id2 = kex->session_id;
2435 session_id2_len = kex->session_id_len;
2438 /* send 1st encrypted/maced/compressed message */
2439 packet_start(SSH2_MSG_IGNORE);
2440 packet_put_cstring("markus");
2442 packet_write_wait();
2447 /* server specific fatal cleanup */
2452 do_cleanup(the_authctxt);
2453 #ifdef SSH_AUDIT_EVENTS
2454 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2455 if (!use_privsep || mm_is_monitor())
2456 audit_event(SSH_CONNECTION_ABANDON);