1 /* $OpenBSD: sshd.c,v 1.374 2010/03/07 11:57:13 dtucker 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.
48 #include <sys/types.h>
49 #include <sys/ioctl.h>
51 #include <sys/socket.h>
52 #ifdef HAVE_SYS_STAT_H
53 # include <sys/stat.h>
55 #ifdef HAVE_SYS_TIME_H
56 # include <sys/time.h>
58 #include "openbsd-compat/sys-tree.h"
59 #include "openbsd-compat/sys-queue.h"
77 #include <openssl/dh.h>
78 #include <openssl/bn.h>
79 #include <openssl/md5.h>
80 #include <openssl/rand.h>
81 #include "openbsd-compat/openssl-compat.h"
83 #ifdef HAVE_SECUREWARE
84 #include <sys/security.h>
90 #if defined(GSSAPI) && defined(HAVE_GSSAPI_H)
92 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H)
93 #include <gssapi/gssapi.h>
106 #include "servconf.h"
113 #include "myproposal.h"
114 #include "authfile.h"
115 #include "pathnames.h"
116 #include "atomicio.h"
117 #include "canohost.h"
118 #include "hostfile.h"
122 #include "dispatch.h"
123 #include "channels.h"
125 #include "monitor_mm.h"
130 #include "monitor_wrap.h"
146 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
147 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
148 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
149 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
151 extern char *__progname;
153 /* Server configuration options. */
154 ServerOptions options;
156 /* Name of the server configuration file. */
157 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
160 * Debug mode flag. This can be set on the command line. If debug
161 * mode is enabled, extra debugging output will be sent to the system
162 * log, the daemon will not go to background, and will exit after processing
163 * the first connection.
167 /* Flag indicating that the daemon should only test the configuration and keys. */
170 /* Flag indicating that the daemon is being started from inetd. */
173 /* Flag indicating that sshd should not detach and become a daemon. */
174 int no_daemon_flag = 0;
176 /* debug goes to stderr unless inetd_flag is set */
179 /* Saved arguments to main(). */
184 int rexeced_flag = 0;
190 * The sockets that the server is listening; this is used in the SIGHUP
193 #define MAX_LISTEN_SOCKS 16
194 int listen_socks[MAX_LISTEN_SOCKS];
195 int num_listen_socks = 0;
198 * the client's version string, passed by sshd2 in compat mode. if != NULL,
199 * sshd will skip the version-number exchange
201 char *client_version_string = NULL;
202 char *server_version_string = NULL;
204 /* for rekeying XXX fixme */
208 * Any really sensitive data in the application is contained in this
209 * structure. The idea is that this structure could be locked into memory so
210 * that the pages do not get written into swap. However, there are some
211 * problems. The private key contains BIGNUMs, and we do not (in principle)
212 * have access to the internals of them, and locking just the structure is
213 * not very useful. Currently, memory locking is not implemented.
216 Key *server_key; /* ephemeral server key */
217 Key *ssh1_host_key; /* ssh1 host key */
218 Key **host_keys; /* all private host keys */
219 Key **host_certificates; /* all public host certificates */
222 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
226 * Flag indicating whether the RSA server key needs to be regenerated.
227 * Is set in the SIGALRM handler and cleared when the key is regenerated.
229 static volatile sig_atomic_t key_do_regen = 0;
231 /* This is set to true when a signal is received. */
232 static volatile sig_atomic_t received_sighup = 0;
233 static volatile sig_atomic_t received_sigterm = 0;
235 /* session identifier, used by RSA-auth */
236 u_char session_id[16];
239 u_char *session_id2 = NULL;
240 u_int session_id2_len = 0;
242 /* record remote hostname or ip */
243 u_int utmp_len = MAXHOSTNAMELEN;
245 /* options.max_startup sized array of fd ints */
246 int *startup_pipes = NULL;
247 int startup_pipe; /* in child */
249 /* variables used for privilege separation */
250 int use_privsep = -1;
251 struct monitor *pmonitor = NULL;
253 /* global authentication context */
254 Authctxt *the_authctxt = NULL;
256 /* sshd_config buffer */
259 /* message to be displayed after login */
262 /* Unprivileged user */
263 struct passwd *privsep_pw = NULL;
265 /* Prototypes for various functions defined later in this file. */
266 void destroy_sensitive_data(void);
267 void demote_sensitive_data(void);
269 static void do_ssh1_kex(void);
270 static void do_ssh2_kex(void);
273 * Close all listening sockets
276 close_listen_socks(void)
280 for (i = 0; i < num_listen_socks; i++)
281 close(listen_socks[i]);
282 num_listen_socks = -1;
286 close_startup_pipes(void)
291 for (i = 0; i < options.max_startups; i++)
292 if (startup_pipes[i] != -1)
293 close(startup_pipes[i]);
297 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
298 * the effect is to reread the configuration file (and to regenerate
304 sighup_handler(int sig)
306 int save_errno = errno;
309 signal(SIGHUP, sighup_handler);
314 * Called from the main program after receiving SIGHUP.
315 * Restarts the server.
320 logit("Received SIGHUP; restarting.");
321 close_listen_socks();
322 close_startup_pipes();
323 alarm(0); /* alarm timer persists across exec */
324 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
325 execv(saved_argv[0], saved_argv);
326 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
332 * Generic signal handler for terminating signals in the master daemon.
336 sigterm_handler(int sig)
338 received_sigterm = sig;
342 * SIGCHLD handler. This is called whenever a child dies. This will then
343 * reap any zombies left by exited children.
347 main_sigchld_handler(int sig)
349 int save_errno = errno;
353 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
354 (pid < 0 && errno == EINTR))
357 signal(SIGCHLD, main_sigchld_handler);
362 * Signal handler for the alarm after the login grace period has expired.
366 grace_alarm_handler(int sig)
368 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
369 kill(pmonitor->m_pid, SIGALRM);
371 /* Log error and exit. */
372 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
376 * Signal handler for the key regeneration alarm. Note that this
377 * alarm only occurs in the daemon waiting for connections, and it does not
378 * do anything with the private key or random state before forking.
379 * Thus there should be no concurrency control/asynchronous execution
383 generate_ephemeral_server_key(void)
385 verbose("Generating %s%d bit RSA key.",
386 sensitive_data.server_key ? "new " : "", options.server_key_bits);
387 if (sensitive_data.server_key != NULL)
388 key_free(sensitive_data.server_key);
389 sensitive_data.server_key = key_generate(KEY_RSA1,
390 options.server_key_bits);
391 verbose("RSA key generation complete.");
393 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
399 key_regeneration_alarm(int sig)
401 int save_errno = errno;
403 signal(SIGALRM, SIG_DFL);
409 sshd_exchange_identification(int sock_in, int sock_out)
413 int remote_major, remote_minor;
415 char *s, *newline = "\n";
416 char buf[256]; /* Must not be larger than remote_version. */
417 char remote_version[256]; /* Must be at least as big as buf. */
419 if ((options.protocol & SSH_PROTO_1) &&
420 (options.protocol & SSH_PROTO_2)) {
421 major = PROTOCOL_MAJOR_1;
423 } else if (options.protocol & SSH_PROTO_2) {
424 major = PROTOCOL_MAJOR_2;
425 minor = PROTOCOL_MINOR_2;
428 major = PROTOCOL_MAJOR_1;
429 minor = PROTOCOL_MINOR_1;
431 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
432 SSH_VERSION, newline);
433 server_version_string = xstrdup(buf);
435 /* Send our protocol version identification. */
436 if (roaming_atomicio(vwrite, sock_out, server_version_string,
437 strlen(server_version_string))
438 != strlen(server_version_string)) {
439 logit("Could not write ident string to %s", get_remote_ipaddr());
443 /* Read other sides version identification. */
444 memset(buf, 0, sizeof(buf));
445 for (i = 0; i < sizeof(buf) - 1; i++) {
446 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
447 logit("Did not receive identification string from %s",
448 get_remote_ipaddr());
451 if (buf[i] == '\r') {
453 /* Kludge for F-Secure Macintosh < 1.0.2 */
455 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
459 if (buf[i] == '\n') {
464 buf[sizeof(buf) - 1] = 0;
465 client_version_string = xstrdup(buf);
468 * Check that the versions match. In future this might accept
469 * several versions and set appropriate flags to handle them.
471 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
472 &remote_major, &remote_minor, remote_version) != 3) {
473 s = "Protocol mismatch.\n";
474 (void) atomicio(vwrite, sock_out, s, strlen(s));
477 logit("Bad protocol version identification '%.100s' from %s",
478 client_version_string, get_remote_ipaddr());
481 debug("Client protocol version %d.%d; client software version %.100s",
482 remote_major, remote_minor, remote_version);
484 compat_datafellows(remote_version);
486 if (datafellows & SSH_BUG_PROBE) {
487 logit("probed from %s with %s. Don't panic.",
488 get_remote_ipaddr(), client_version_string);
492 if (datafellows & SSH_BUG_SCANNER) {
493 logit("scanned from %s with %s. Don't panic.",
494 get_remote_ipaddr(), client_version_string);
499 switch (remote_major) {
501 if (remote_minor == 99) {
502 if (options.protocol & SSH_PROTO_2)
508 if (!(options.protocol & SSH_PROTO_1)) {
512 if (remote_minor < 3) {
513 packet_disconnect("Your ssh version is too old and "
514 "is no longer supported. Please install a newer version.");
515 } else if (remote_minor == 3) {
516 /* note that this disables agent-forwarding */
521 if (options.protocol & SSH_PROTO_2) {
530 chop(server_version_string);
531 debug("Local version string %.200s", server_version_string);
534 s = "Protocol major versions differ.\n";
535 (void) atomicio(vwrite, sock_out, s, strlen(s));
538 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
540 server_version_string, client_version_string);
545 /* Destroy the host and server keys. They will no longer be needed. */
547 destroy_sensitive_data(void)
551 if (sensitive_data.server_key) {
552 key_free(sensitive_data.server_key);
553 sensitive_data.server_key = NULL;
555 for (i = 0; i < options.num_host_key_files; i++) {
556 if (sensitive_data.host_keys[i]) {
557 key_free(sensitive_data.host_keys[i]);
558 sensitive_data.host_keys[i] = NULL;
560 if (sensitive_data.host_certificates[i]) {
561 key_free(sensitive_data.host_certificates[i]);
562 sensitive_data.host_certificates[i] = NULL;
565 sensitive_data.ssh1_host_key = NULL;
566 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
569 /* Demote private to public keys for network child */
571 demote_sensitive_data(void)
576 if (sensitive_data.server_key) {
577 tmp = key_demote(sensitive_data.server_key);
578 key_free(sensitive_data.server_key);
579 sensitive_data.server_key = tmp;
582 for (i = 0; i < options.num_host_key_files; i++) {
583 if (sensitive_data.host_keys[i]) {
584 tmp = key_demote(sensitive_data.host_keys[i]);
585 key_free(sensitive_data.host_keys[i]);
586 sensitive_data.host_keys[i] = tmp;
587 if (tmp->type == KEY_RSA1)
588 sensitive_data.ssh1_host_key = tmp;
590 /* Certs do not need demotion */
593 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
597 privsep_preauth_child(void)
602 /* Enable challenge-response authentication for privilege separation */
603 privsep_challenge_enable();
606 arc4random_buf(rnd, sizeof(rnd));
607 RAND_seed(rnd, sizeof(rnd));
609 /* Demote the private keys to public keys. */
610 demote_sensitive_data();
612 /* Change our root directory */
613 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
614 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
616 if (chdir("/") == -1)
617 fatal("chdir(\"/\"): %s", strerror(errno));
619 /* Drop our privileges */
620 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
621 (u_int)privsep_pw->pw_gid);
623 /* XXX not ready, too heavy after chroot */
624 do_setusercontext(privsep_pw);
626 gidset[0] = privsep_pw->pw_gid;
627 if (setgroups(1, gidset) < 0)
628 fatal("setgroups: %.100s", strerror(errno));
629 permanently_set_uid(privsep_pw);
634 privsep_preauth(Authctxt *authctxt)
639 /* Set up unprivileged child process to deal with network data */
640 pmonitor = monitor_init();
641 /* Store a pointer to the kex for later rekeying */
642 pmonitor->m_pkex = &xxx_kex;
646 fatal("fork of unprivileged child failed");
647 } else if (pid != 0) {
648 debug2("Network child is on pid %ld", (long)pid);
650 close(pmonitor->m_recvfd);
651 pmonitor->m_pid = pid;
652 monitor_child_preauth(authctxt, pmonitor);
653 close(pmonitor->m_sendfd);
656 monitor_sync(pmonitor);
658 /* Wait for the child's exit status */
659 while (waitpid(pid, &status, 0) < 0)
666 close(pmonitor->m_sendfd);
668 /* Demote the child */
669 if (getuid() == 0 || geteuid() == 0)
670 privsep_preauth_child();
671 setproctitle("%s", "[net]");
677 privsep_postauth(Authctxt *authctxt)
681 #ifdef DISABLE_FD_PASSING
684 if (authctxt->pw->pw_uid == 0 || options.use_login) {
686 /* File descriptor passing is broken or root login */
691 /* New socket pair */
692 monitor_reinit(pmonitor);
694 pmonitor->m_pid = fork();
695 if (pmonitor->m_pid == -1)
696 fatal("fork of unprivileged child failed");
697 else if (pmonitor->m_pid != 0) {
698 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
699 close(pmonitor->m_recvfd);
700 buffer_clear(&loginmsg);
701 monitor_child_postauth(pmonitor);
707 close(pmonitor->m_sendfd);
709 /* Demote the private keys to public keys. */
710 demote_sensitive_data();
713 arc4random_buf(rnd, sizeof(rnd));
714 RAND_seed(rnd, sizeof(rnd));
716 /* Drop privileges */
717 do_setusercontext(authctxt->pw);
720 /* It is safe now to apply the key state */
721 monitor_apply_keystate(pmonitor);
724 * Tell the packet layer that authentication was successful, since
725 * this information is not part of the key state.
727 packet_set_authenticated();
731 list_hostkey_types(void)
740 for (i = 0; i < options.num_host_key_files; i++) {
741 key = sensitive_data.host_keys[i];
747 if (buffer_len(&b) > 0)
748 buffer_append(&b, ",", 1);
749 p = key_ssh_name(key);
750 buffer_append(&b, p, strlen(p));
753 /* If the private key has a cert peer, then list that too */
754 key = sensitive_data.host_certificates[i];
760 if (buffer_len(&b) > 0)
761 buffer_append(&b, ",", 1);
762 p = key_ssh_name(key);
763 buffer_append(&b, p, strlen(p));
767 buffer_append(&b, "\0", 1);
768 ret = xstrdup(buffer_ptr(&b));
770 debug("list_hostkey_types: %s", ret);
775 get_hostkey_by_type(int type, int need_private)
780 for (i = 0; i < options.num_host_key_files; i++) {
781 if (type == KEY_RSA_CERT || type == KEY_DSA_CERT)
782 key = sensitive_data.host_certificates[i];
784 key = sensitive_data.host_keys[i];
785 if (key != NULL && key->type == type)
786 return need_private ?
787 sensitive_data.host_keys[i] : key;
793 get_hostkey_public_by_type(int type)
795 return get_hostkey_by_type(type, 0);
799 get_hostkey_private_by_type(int type)
801 return get_hostkey_by_type(type, 1);
805 get_hostkey_by_index(int ind)
807 if (ind < 0 || ind >= options.num_host_key_files)
809 return (sensitive_data.host_keys[ind]);
813 get_hostkey_index(Key *key)
817 for (i = 0; i < options.num_host_key_files; i++) {
818 if (key_is_cert(key)) {
819 if (key == sensitive_data.host_certificates[i])
822 if (key == sensitive_data.host_keys[i])
830 * returns 1 if connection should be dropped, 0 otherwise.
831 * dropping starts at connection #max_startups_begin with a probability
832 * of (max_startups_rate/100). the probability increases linearly until
833 * all connections are dropped for startups > max_startups
836 drop_connection(int startups)
840 if (startups < options.max_startups_begin)
842 if (startups >= options.max_startups)
844 if (options.max_startups_rate == 100)
847 p = 100 - options.max_startups_rate;
848 p *= startups - options.max_startups_begin;
849 p /= options.max_startups - options.max_startups_begin;
850 p += options.max_startups_rate;
851 r = arc4random_uniform(100);
853 debug("drop_connection: p %d, r %d", p, r);
854 return (r < p) ? 1 : 0;
860 fprintf(stderr, "%s, %s\n",
861 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
863 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
864 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
865 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
871 send_rexec_state(int fd, Buffer *conf)
875 debug3("%s: entering fd = %d config len %d", __func__, fd,
879 * Protocol from reexec master to child:
880 * string configuration
881 * u_int ephemeral_key_follows
882 * bignum e (only if ephemeral_key_follows == 1)
888 * string rngseed (only if OpenSSL is not self-seeded)
891 buffer_put_cstring(&m, buffer_ptr(conf));
893 if (sensitive_data.server_key != NULL &&
894 sensitive_data.server_key->type == KEY_RSA1) {
895 buffer_put_int(&m, 1);
896 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
897 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
898 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
899 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
900 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
901 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
903 buffer_put_int(&m, 0);
905 #ifndef OPENSSL_PRNG_ONLY
906 rexec_send_rng_seed(&m);
909 if (ssh_msg_send(fd, 0, &m) == -1)
910 fatal("%s: ssh_msg_send failed", __func__);
914 debug3("%s: done", __func__);
918 recv_rexec_state(int fd, Buffer *conf)
924 debug3("%s: entering fd = %d", __func__, fd);
928 if (ssh_msg_recv(fd, &m) == -1)
929 fatal("%s: ssh_msg_recv failed", __func__);
930 if (buffer_get_char(&m) != 0)
931 fatal("%s: rexec version mismatch", __func__);
933 cp = buffer_get_string(&m, &len);
935 buffer_append(conf, cp, len + 1);
938 if (buffer_get_int(&m)) {
939 if (sensitive_data.server_key != NULL)
940 key_free(sensitive_data.server_key);
941 sensitive_data.server_key = key_new_private(KEY_RSA1);
942 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
943 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
944 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
945 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
946 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
947 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
948 rsa_generate_additional_parameters(
949 sensitive_data.server_key->rsa);
952 #ifndef OPENSSL_PRNG_ONLY
953 rexec_recv_rng_seed(&m);
958 debug3("%s: done", __func__);
961 /* Accept a connection from inetd */
963 server_accept_inetd(int *sock_in, int *sock_out)
969 close(REEXEC_CONFIG_PASS_FD);
970 *sock_in = *sock_out = dup(STDIN_FILENO);
972 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
973 close(REEXEC_STARTUP_PIPE_FD);
976 *sock_in = dup(STDIN_FILENO);
977 *sock_out = dup(STDOUT_FILENO);
980 * We intentionally do not close the descriptors 0, 1, and 2
981 * as our code for setting the descriptors won't work if
982 * ttyfd happens to be one of those.
984 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
985 dup2(fd, STDIN_FILENO);
986 dup2(fd, STDOUT_FILENO);
987 if (fd > STDOUT_FILENO)
990 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
994 * Listen for TCP connections
999 int ret, listen_sock, on = 1;
1000 struct addrinfo *ai;
1001 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1003 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1004 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1006 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1007 fatal("Too many listen sockets. "
1008 "Enlarge MAX_LISTEN_SOCKS");
1009 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1010 ntop, sizeof(ntop), strport, sizeof(strport),
1011 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1012 error("getnameinfo failed: %.100s",
1013 ssh_gai_strerror(ret));
1016 /* Create socket for listening. */
1017 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1019 if (listen_sock < 0) {
1020 /* kernel may not support ipv6 */
1021 verbose("socket: %.100s", strerror(errno));
1024 if (set_nonblock(listen_sock) == -1) {
1029 * Set socket options.
1030 * Allow local port reuse in TIME_WAIT.
1032 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1033 &on, sizeof(on)) == -1)
1034 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1036 /* Only communicate in IPv6 over AF_INET6 sockets. */
1037 if (ai->ai_family == AF_INET6)
1038 sock_set_v6only(listen_sock);
1040 debug("Bind to port %s on %s.", strport, ntop);
1042 /* Bind the socket to the desired port. */
1043 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1044 error("Bind to port %s on %s failed: %.200s.",
1045 strport, ntop, strerror(errno));
1049 listen_socks[num_listen_socks] = listen_sock;
1052 /* Start listening on the port. */
1053 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1054 fatal("listen on [%s]:%s: %.100s",
1055 ntop, strport, strerror(errno));
1056 logit("Server listening on %s port %s.", ntop, strport);
1058 freeaddrinfo(options.listen_addrs);
1060 if (!num_listen_socks)
1061 fatal("Cannot bind any address.");
1065 * The main TCP accept loop. Note that, for the non-debug case, returns
1066 * from this function are in a forked subprocess.
1069 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1072 int i, j, ret, maxfd;
1073 int key_used = 0, startups = 0;
1074 int startup_p[2] = { -1 , -1 };
1075 struct sockaddr_storage from;
1079 /* setup fd set for accept */
1082 for (i = 0; i < num_listen_socks; i++)
1083 if (listen_socks[i] > maxfd)
1084 maxfd = listen_socks[i];
1085 /* pipes connected to unauthenticated childs */
1086 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1087 for (i = 0; i < options.max_startups; i++)
1088 startup_pipes[i] = -1;
1091 * Stay listening for connections until the system crashes or
1092 * the daemon is killed with a signal.
1095 if (received_sighup)
1099 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1102 for (i = 0; i < num_listen_socks; i++)
1103 FD_SET(listen_socks[i], fdset);
1104 for (i = 0; i < options.max_startups; i++)
1105 if (startup_pipes[i] != -1)
1106 FD_SET(startup_pipes[i], fdset);
1108 /* Wait in select until there is a connection. */
1109 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1110 if (ret < 0 && errno != EINTR)
1111 error("select: %.100s", strerror(errno));
1112 if (received_sigterm) {
1113 logit("Received signal %d; terminating.",
1114 (int) received_sigterm);
1115 close_listen_socks();
1116 unlink(options.pid_file);
1119 if (key_used && key_do_regen) {
1120 generate_ephemeral_server_key();
1127 for (i = 0; i < options.max_startups; i++)
1128 if (startup_pipes[i] != -1 &&
1129 FD_ISSET(startup_pipes[i], fdset)) {
1131 * the read end of the pipe is ready
1132 * if the child has closed the pipe
1133 * after successful authentication
1134 * or if the child has died
1136 close(startup_pipes[i]);
1137 startup_pipes[i] = -1;
1140 for (i = 0; i < num_listen_socks; i++) {
1141 if (!FD_ISSET(listen_socks[i], fdset))
1143 fromlen = sizeof(from);
1144 *newsock = accept(listen_socks[i],
1145 (struct sockaddr *)&from, &fromlen);
1147 if (errno != EINTR && errno != EAGAIN &&
1148 errno != EWOULDBLOCK)
1149 error("accept: %.100s", strerror(errno));
1152 if (unset_nonblock(*newsock) == -1) {
1156 if (drop_connection(startups) == 1) {
1157 debug("drop connection #%d", startups);
1161 if (pipe(startup_p) == -1) {
1166 if (rexec_flag && socketpair(AF_UNIX,
1167 SOCK_STREAM, 0, config_s) == -1) {
1168 error("reexec socketpair: %s",
1171 close(startup_p[0]);
1172 close(startup_p[1]);
1176 for (j = 0; j < options.max_startups; j++)
1177 if (startup_pipes[j] == -1) {
1178 startup_pipes[j] = startup_p[0];
1179 if (maxfd < startup_p[0])
1180 maxfd = startup_p[0];
1186 * Got connection. Fork a child to handle it, unless
1187 * we are in debugging mode.
1191 * In debugging mode. Close the listening
1192 * socket, and start processing the
1193 * connection without forking.
1195 debug("Server will not fork when running in debugging mode.");
1196 close_listen_socks();
1197 *sock_in = *newsock;
1198 *sock_out = *newsock;
1199 close(startup_p[0]);
1200 close(startup_p[1]);
1204 send_rexec_state(config_s[0],
1212 * Normal production daemon. Fork, and have
1213 * the child process the connection. The
1214 * parent continues listening.
1216 platform_pre_fork();
1217 if ((pid = fork()) == 0) {
1219 * Child. Close the listening and
1220 * max_startup sockets. Start using
1221 * the accepted socket. Reinitialize
1222 * logging (since our pid has changed).
1223 * We break out of the loop to handle
1226 platform_post_fork_child();
1227 startup_pipe = startup_p[1];
1228 close_startup_pipes();
1229 close_listen_socks();
1230 *sock_in = *newsock;
1231 *sock_out = *newsock;
1232 log_init(__progname,
1234 options.log_facility,
1241 /* Parent. Stay in the loop. */
1242 platform_post_fork_parent(pid);
1244 error("fork: %.100s", strerror(errno));
1246 debug("Forked child %ld.", (long)pid);
1248 close(startup_p[1]);
1251 send_rexec_state(config_s[0], &cfg);
1257 * Mark that the key has been used (it
1258 * was "given" to the child).
1260 if ((options.protocol & SSH_PROTO_1) &&
1262 /* Schedule server key regeneration alarm. */
1263 signal(SIGALRM, key_regeneration_alarm);
1264 alarm(options.key_regeneration_time);
1271 * Ensure that our random state differs
1272 * from that of the child
1277 /* child process check (or debug mode) */
1278 if (num_listen_socks < 0)
1285 * Main program for the daemon.
1288 main(int ac, char **av)
1290 extern char *optarg;
1292 int opt, i, j, on = 1;
1293 int sock_in = -1, sock_out = -1, newsock = -1;
1294 const char *remote_ip;
1295 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1297 char *line, *p, *cp;
1298 int config_s[2] = { -1 , -1 };
1299 u_int64_t ibytes, obytes;
1304 #ifdef HAVE_SECUREWARE
1305 (void)set_auth_parameters(ac, av);
1307 __progname = ssh_get_progname(av[0]);
1310 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1313 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1314 for (i = 0; i < ac; i++)
1315 saved_argv[i] = xstrdup(av[i]);
1316 saved_argv[i] = NULL;
1318 #ifndef HAVE_SETPROCTITLE
1319 /* Prepare for later setproctitle emulation */
1320 compat_init_setproctitle(ac, av);
1324 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1325 debug("setgroups(): %.200s", strerror(errno));
1327 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1330 /* Initialize configuration options to their default values. */
1331 initialize_server_options(&options);
1333 /* Avoid killing the process in high-pressure swapping environments. */
1334 if (madvise(NULL, 0, MADV_PROTECT) != 0)
1335 debug("madvise(): %.200s", strerror(errno));
1337 /* Parse command-line arguments. */
1338 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1341 options.address_family = AF_INET;
1344 options.address_family = AF_INET6;
1347 config_file_name = optarg;
1350 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1351 fprintf(stderr, "too many host certificates.\n");
1354 options.host_cert_files[options.num_host_cert_files++] =
1355 derelativise_path(optarg);
1358 if (debug_flag == 0) {
1360 options.log_level = SYSLOG_LEVEL_DEBUG1;
1361 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1362 options.log_level++;
1384 options.log_level = SYSLOG_LEVEL_QUIET;
1387 options.server_key_bits = (int)strtonum(optarg, 256,
1391 options.ports_from_cmdline = 1;
1392 if (options.num_ports >= MAX_PORTS) {
1393 fprintf(stderr, "too many ports.\n");
1396 options.ports[options.num_ports++] = a2port(optarg);
1397 if (options.ports[options.num_ports-1] <= 0) {
1398 fprintf(stderr, "Bad port number.\n");
1403 if ((options.login_grace_time = convtime(optarg)) == -1) {
1404 fprintf(stderr, "Invalid login grace time.\n");
1409 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1410 fprintf(stderr, "Invalid key regeneration interval.\n");
1415 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1416 fprintf(stderr, "too many host keys.\n");
1419 options.host_key_files[options.num_host_key_files++] =
1420 derelativise_path(optarg);
1430 while ((p = strsep(&cp, ",")) && *p != '\0') {
1431 if (strncmp(p, "addr=", 5) == 0)
1432 test_addr = xstrdup(p + 5);
1433 else if (strncmp(p, "host=", 5) == 0)
1434 test_host = xstrdup(p + 5);
1435 else if (strncmp(p, "user=", 5) == 0)
1436 test_user = xstrdup(p + 5);
1438 fprintf(stderr, "Invalid test "
1439 "mode specification %s\n", p);
1445 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1446 if (utmp_len > MAXHOSTNAMELEN) {
1447 fprintf(stderr, "Invalid utmp length.\n");
1452 line = xstrdup(optarg);
1453 if (process_server_config_line(&options, line,
1454 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1464 if (rexeced_flag || inetd_flag)
1466 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1467 fatal("sshd re-exec requires execution with an absolute path");
1469 closefrom(REEXEC_MIN_FREE_FD);
1471 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1473 SSLeay_add_all_algorithms();
1476 * Force logging to stderr until we have loaded the private host
1477 * key (unless started from inetd)
1479 log_init(__progname,
1480 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1481 SYSLOG_LEVEL_INFO : options.log_level,
1482 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1483 SYSLOG_FACILITY_AUTH : options.log_facility,
1484 log_stderr || !inetd_flag);
1487 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1488 * root's environment
1490 if (getenv("KRB5CCNAME") != NULL)
1491 unsetenv("KRB5CCNAME");
1494 /* Cray can define user privs drop all privs now!
1495 * Not needed on PRIV_SU systems!
1500 sensitive_data.server_key = NULL;
1501 sensitive_data.ssh1_host_key = NULL;
1502 sensitive_data.have_ssh1_key = 0;
1503 sensitive_data.have_ssh2_key = 0;
1506 * If we're doing an extended config test, make sure we have all of
1507 * the parameters we need. If we're not doing an extended test,
1508 * do not silently ignore connection test params.
1510 if (test_flag >= 2 &&
1511 (test_user != NULL || test_host != NULL || test_addr != NULL)
1512 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1513 fatal("user, host and addr are all required when testing "
1515 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1517 fatal("Config test connection parameter (-C) provided without "
1520 /* Fetch our configuration */
1523 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1525 load_server_config(config_file_name, &cfg);
1527 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1528 &cfg, NULL, NULL, NULL);
1532 /* Fill in default values for those options not explicitly set. */
1533 fill_default_server_options(&options);
1535 /* challenge-response is implemented via keyboard interactive */
1536 if (options.challenge_response_authentication)
1537 options.kbd_interactive_authentication = 1;
1539 /* set default channel AF */
1540 channel_set_af(options.address_family);
1542 /* Check that there are no remaining arguments. */
1544 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1548 debug("sshd version %.100s", SSH_RELEASE);
1550 /* Store privilege separation user for later use if required. */
1551 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1552 if (use_privsep || options.kerberos_authentication)
1553 fatal("Privilege separation user %s does not exist",
1556 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1557 privsep_pw = pwcopy(privsep_pw);
1558 xfree(privsep_pw->pw_passwd);
1559 privsep_pw->pw_passwd = xstrdup("*");
1563 /* load private host keys */
1564 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1566 for (i = 0; i < options.num_host_key_files; i++)
1567 sensitive_data.host_keys[i] = NULL;
1569 for (i = 0; i < options.num_host_key_files; i++) {
1570 key = key_load_private(options.host_key_files[i], "", NULL);
1571 sensitive_data.host_keys[i] = key;
1573 error("Could not load host key: %s",
1574 options.host_key_files[i]);
1575 sensitive_data.host_keys[i] = NULL;
1578 switch (key->type) {
1580 sensitive_data.ssh1_host_key = key;
1581 sensitive_data.have_ssh1_key = 1;
1585 sensitive_data.have_ssh2_key = 1;
1588 debug("private host key: #%d type %d %s", i, key->type,
1591 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1592 logit("Disabling protocol version 1. Could not load host key");
1593 options.protocol &= ~SSH_PROTO_1;
1595 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1596 logit("Disabling protocol version 2. Could not load host key");
1597 options.protocol &= ~SSH_PROTO_2;
1599 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1600 logit("sshd: no hostkeys available -- exiting.");
1605 * Load certificates. They are stored in an array at identical
1606 * indices to the public keys that they relate to.
1608 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1610 for (i = 0; i < options.num_host_key_files; i++)
1611 sensitive_data.host_certificates[i] = NULL;
1613 for (i = 0; i < options.num_host_cert_files; i++) {
1614 key = key_load_public(options.host_cert_files[i], NULL);
1616 error("Could not load host certificate: %s",
1617 options.host_cert_files[i]);
1620 if (!key_is_cert(key)) {
1621 error("Certificate file is not a certificate: %s",
1622 options.host_cert_files[i]);
1626 /* Find matching private key */
1627 for (j = 0; j < options.num_host_key_files; j++) {
1628 if (key_equal_public(key,
1629 sensitive_data.host_keys[j])) {
1630 sensitive_data.host_certificates[j] = key;
1634 if (j >= options.num_host_key_files) {
1635 error("No matching private key for certificate: %s",
1636 options.host_cert_files[i]);
1640 sensitive_data.host_certificates[j] = key;
1641 debug("host certificate: #%d type %d %s", j, key->type,
1644 /* Check certain values for sanity. */
1645 if (options.protocol & SSH_PROTO_1) {
1646 if (options.server_key_bits < 512 ||
1647 options.server_key_bits > 32768) {
1648 fprintf(stderr, "Bad server key size.\n");
1652 * Check that server and host key lengths differ sufficiently. This
1653 * is necessary to make double encryption work with rsaref. Oh, I
1654 * hate software patents. I dont know if this can go? Niels
1656 if (options.server_key_bits >
1657 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1658 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1659 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1660 SSH_KEY_BITS_RESERVED) {
1661 options.server_key_bits =
1662 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1663 SSH_KEY_BITS_RESERVED;
1664 debug("Forcing server key to %d bits to make it differ from host key.",
1665 options.server_key_bits);
1672 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1673 (S_ISDIR(st.st_mode) == 0))
1674 fatal("Missing privilege separation directory: %s",
1675 _PATH_PRIVSEP_CHROOT_DIR);
1678 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1679 (st.st_uid != getuid () ||
1680 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1682 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1684 fatal("%s must be owned by root and not group or "
1685 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1688 if (test_flag > 1) {
1689 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1690 parse_server_match_config(&options, test_user,
1691 test_host, test_addr);
1692 dump_config(&options);
1695 /* Configuration looks good, so exit if in test mode. */
1700 * Clear out any supplemental groups we may have inherited. This
1701 * prevents inadvertent creation of files with bad modes (in the
1702 * portable version at least, it's certainly possible for PAM
1703 * to create a file, and we can't control the code in every
1704 * module which might be used).
1706 if (setgroups(0, NULL) < 0)
1707 debug("setgroups() failed: %.200s", strerror(errno));
1710 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1711 for (i = 0; i < rexec_argc; i++) {
1712 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1713 rexec_argv[i] = saved_argv[i];
1715 rexec_argv[rexec_argc] = "-R";
1716 rexec_argv[rexec_argc + 1] = NULL;
1719 /* Ensure that umask disallows at least group and world write */
1720 new_umask = umask(0077) | 0022;
1721 (void) umask(new_umask);
1723 /* Initialize the log (it is reinitialized below in case we forked). */
1724 if (debug_flag && (!inetd_flag || rexeced_flag))
1726 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1729 * If not in debugging mode, and not started from inetd, disconnect
1730 * from the controlling terminal, and fork. The original process
1733 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1736 #endif /* TIOCNOTTY */
1737 if (daemon(0, 0) < 0)
1738 fatal("daemon() failed: %.200s", strerror(errno));
1740 /* Disconnect from the controlling tty. */
1742 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1744 (void) ioctl(fd, TIOCNOTTY, NULL);
1747 #endif /* TIOCNOTTY */
1749 /* Reinitialize the log (because of the fork above). */
1750 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1752 /* Initialize the random number generator. */
1755 /* Chdir to the root directory so that the current disk can be
1756 unmounted if desired. */
1759 /* ignore SIGPIPE */
1760 signal(SIGPIPE, SIG_IGN);
1762 /* Get a connection, either from inetd or a listening TCP socket */
1764 server_accept_inetd(&sock_in, &sock_out);
1766 platform_pre_listen();
1769 if (options.protocol & SSH_PROTO_1)
1770 generate_ephemeral_server_key();
1772 signal(SIGHUP, sighup_handler);
1773 signal(SIGCHLD, main_sigchld_handler);
1774 signal(SIGTERM, sigterm_handler);
1775 signal(SIGQUIT, sigterm_handler);
1778 * Write out the pid file after the sigterm handler
1779 * is setup and the listen sockets are bound
1782 FILE *f = fopen(options.pid_file, "w");
1785 error("Couldn't create pid file \"%s\": %s",
1786 options.pid_file, strerror(errno));
1788 fprintf(f, "%ld\n", (long) getpid());
1793 /* Accept a connection and return in a forked child */
1794 server_accept_loop(&sock_in, &sock_out,
1795 &newsock, config_s);
1798 /* This is the child processing a new connection. */
1799 setproctitle("%s", "[accepted]");
1802 * Create a new session and process group since the 4.4BSD
1803 * setlogin() affects the entire process group. We don't
1804 * want the child to be able to affect the parent.
1806 #if !defined(SSHD_ACQUIRES_CTTY)
1808 * If setsid is called, on some platforms sshd will later acquire a
1809 * controlling terminal which will result in "could not set
1810 * controlling tty" errors.
1812 if (!debug_flag && !inetd_flag && setsid() < 0)
1813 error("setsid: %.100s", strerror(errno));
1819 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1820 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1821 dup2(newsock, STDIN_FILENO);
1822 dup2(STDIN_FILENO, STDOUT_FILENO);
1823 if (startup_pipe == -1)
1824 close(REEXEC_STARTUP_PIPE_FD);
1826 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1828 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1830 if (startup_pipe != -1)
1831 close(startup_pipe);
1833 execv(rexec_argv[0], rexec_argv);
1835 /* Reexec has failed, fall back and continue */
1836 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1837 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1838 log_init(__progname, options.log_level,
1839 options.log_facility, log_stderr);
1842 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1844 close(REEXEC_CONFIG_PASS_FD);
1845 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1846 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1847 dup2(fd, STDIN_FILENO);
1848 dup2(fd, STDOUT_FILENO);
1849 if (fd > STDERR_FILENO)
1852 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1853 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1856 /* Executed child processes don't need these. */
1857 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1858 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1861 * Disable the key regeneration alarm. We will not regenerate the
1862 * key since we are no longer in a position to give it to anyone. We
1863 * will not restart on SIGHUP since it no longer makes sense.
1866 signal(SIGALRM, SIG_DFL);
1867 signal(SIGHUP, SIG_DFL);
1868 signal(SIGTERM, SIG_DFL);
1869 signal(SIGQUIT, SIG_DFL);
1870 signal(SIGCHLD, SIG_DFL);
1871 signal(SIGINT, SIG_DFL);
1875 * Initialize the resolver. This may not happen automatically
1876 * before privsep chroot().
1878 if ((_res.options & RES_INIT) == 0) {
1879 debug("res_init()");
1884 * Force GSS-API to parse its configuration and load any
1885 * mechanism plugins.
1889 OM_uint32 minor_status;
1890 gss_indicate_mechs(&minor_status, &mechs);
1891 gss_release_oid_set(&minor_status, &mechs);
1897 * Register our connection. This turns encryption off because we do
1900 packet_set_connection(sock_in, sock_out);
1901 packet_set_server();
1903 /* Set SO_KEEPALIVE if requested. */
1904 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1905 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1906 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1908 if ((remote_port = get_remote_port()) < 0) {
1909 debug("get_remote_port failed");
1914 * We use get_canonical_hostname with usedns = 0 instead of
1915 * get_remote_ipaddr here so IP options will be checked.
1917 (void) get_canonical_hostname(0);
1919 * The rest of the code depends on the fact that
1920 * get_remote_ipaddr() caches the remote ip, even if
1921 * the socket goes away.
1923 remote_ip = get_remote_ipaddr();
1925 #ifdef SSH_AUDIT_EVENTS
1926 audit_connection_from(remote_ip, remote_port);
1929 allow_severity = options.log_facility|LOG_INFO;
1930 deny_severity = options.log_facility|LOG_WARNING;
1931 /* Check whether logins are denied from this host. */
1932 if (packet_connection_is_on_socket()) {
1933 struct request_info req;
1935 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1938 if (!hosts_access(&req)) {
1939 debug("Connection refused by tcp wrapper");
1942 fatal("libwrap refuse returns");
1945 #endif /* LIBWRAP */
1947 /* Log the connection. */
1948 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1951 * We don't want to listen forever unless the other side
1952 * successfully authenticates itself. So we set up an alarm which is
1953 * cleared after successful authentication. A limit of zero
1954 * indicates no limit. Note that we don't set the alarm in debugging
1955 * mode; it is just annoying to have the server exit just when you
1956 * are about to discover the bug.
1958 signal(SIGALRM, grace_alarm_handler);
1960 alarm(options.login_grace_time);
1962 sshd_exchange_identification(sock_in, sock_out);
1964 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1965 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1966 generate_ephemeral_server_key();
1968 packet_set_nonblocking();
1970 /* allocate authentication context */
1971 authctxt = xcalloc(1, sizeof(*authctxt));
1973 authctxt->loginmsg = &loginmsg;
1975 /* XXX global for cleanup, access from other modules */
1976 the_authctxt = authctxt;
1978 /* prepare buffer to collect messages to display to user after login */
1979 buffer_init(&loginmsg);
1983 if (privsep_preauth(authctxt) == 1)
1986 /* perform the key exchange */
1987 /* authenticate user and start session */
1990 do_authentication2(authctxt);
1993 do_authentication(authctxt);
1996 * If we use privilege separation, the unprivileged child transfers
1997 * the current keystate and exits
2000 mm_send_keystate(pmonitor);
2006 * Cancel the alarm we set to limit the time taken for
2010 signal(SIGALRM, SIG_DFL);
2011 authctxt->authenticated = 1;
2012 if (startup_pipe != -1) {
2013 close(startup_pipe);
2017 #ifdef SSH_AUDIT_EVENTS
2018 audit_event(SSH_AUTH_SUCCESS);
2022 if (options.gss_authentication) {
2023 temporarily_use_uid(authctxt->pw);
2024 ssh_gssapi_storecreds();
2029 if (options.use_pam) {
2036 * In privilege separation, we fork another child and prepare
2037 * file descriptor passing.
2040 privsep_postauth(authctxt);
2041 /* the monitor process [priv] will not return */
2043 destroy_sensitive_data();
2046 packet_set_timeout(options.client_alive_interval,
2047 options.client_alive_count_max);
2049 /* Start session. */
2050 do_authenticated(authctxt);
2052 /* The connection has been terminated. */
2053 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2054 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2055 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
2057 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2060 if (options.use_pam)
2062 #endif /* USE_PAM */
2064 #ifdef SSH_AUDIT_EVENTS
2065 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2077 * Decrypt session_key_int using our private server key and private host key
2078 * (key with larger modulus first).
2081 ssh1_session_key(BIGNUM *session_key_int)
2085 if (BN_cmp(sensitive_data.server_key->rsa->n,
2086 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2087 /* Server key has bigger modulus. */
2088 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2089 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2090 SSH_KEY_BITS_RESERVED) {
2091 fatal("do_connection: %s: "
2092 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2093 get_remote_ipaddr(),
2094 BN_num_bits(sensitive_data.server_key->rsa->n),
2095 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2096 SSH_KEY_BITS_RESERVED);
2098 if (rsa_private_decrypt(session_key_int, session_key_int,
2099 sensitive_data.server_key->rsa) <= 0)
2101 if (rsa_private_decrypt(session_key_int, session_key_int,
2102 sensitive_data.ssh1_host_key->rsa) <= 0)
2105 /* Host key has bigger modulus (or they are equal). */
2106 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2107 BN_num_bits(sensitive_data.server_key->rsa->n) +
2108 SSH_KEY_BITS_RESERVED) {
2109 fatal("do_connection: %s: "
2110 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2111 get_remote_ipaddr(),
2112 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2113 BN_num_bits(sensitive_data.server_key->rsa->n),
2114 SSH_KEY_BITS_RESERVED);
2116 if (rsa_private_decrypt(session_key_int, session_key_int,
2117 sensitive_data.ssh1_host_key->rsa) < 0)
2119 if (rsa_private_decrypt(session_key_int, session_key_int,
2120 sensitive_data.server_key->rsa) < 0)
2133 BIGNUM *session_key_int;
2134 u_char session_key[SSH_SESSION_KEY_LENGTH];
2136 u_int cipher_type, auth_mask, protocol_flags;
2139 * Generate check bytes that the client must send back in the user
2140 * packet in order for it to be accepted; this is used to defy ip
2141 * spoofing attacks. Note that this only works against somebody
2142 * doing IP spoofing from a remote machine; any machine on the local
2143 * network can still see outgoing packets and catch the random
2144 * cookie. This only affects rhosts authentication, and this is one
2145 * of the reasons why it is inherently insecure.
2147 arc4random_buf(cookie, sizeof(cookie));
2150 * Send our public key. We include in the packet 64 bits of random
2151 * data that must be matched in the reply in order to prevent IP
2154 packet_start(SSH_SMSG_PUBLIC_KEY);
2155 for (i = 0; i < 8; i++)
2156 packet_put_char(cookie[i]);
2158 /* Store our public server RSA key. */
2159 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2160 packet_put_bignum(sensitive_data.server_key->rsa->e);
2161 packet_put_bignum(sensitive_data.server_key->rsa->n);
2163 /* Store our public host RSA key. */
2164 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2165 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2166 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2168 /* Put protocol flags. */
2169 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2171 /* Declare which ciphers we support. */
2172 packet_put_int(cipher_mask_ssh1(0));
2174 /* Declare supported authentication types. */
2176 if (options.rhosts_rsa_authentication)
2177 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2178 if (options.rsa_authentication)
2179 auth_mask |= 1 << SSH_AUTH_RSA;
2180 if (options.challenge_response_authentication == 1)
2181 auth_mask |= 1 << SSH_AUTH_TIS;
2182 if (options.password_authentication)
2183 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2184 packet_put_int(auth_mask);
2186 /* Send the packet and wait for it to be sent. */
2188 packet_write_wait();
2190 debug("Sent %d bit server key and %d bit host key.",
2191 BN_num_bits(sensitive_data.server_key->rsa->n),
2192 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2194 /* Read clients reply (cipher type and session key). */
2195 packet_read_expect(SSH_CMSG_SESSION_KEY);
2197 /* Get cipher type and check whether we accept this. */
2198 cipher_type = packet_get_char();
2200 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2201 packet_disconnect("Warning: client selects unsupported cipher.");
2203 /* Get check bytes from the packet. These must match those we
2204 sent earlier with the public key packet. */
2205 for (i = 0; i < 8; i++)
2206 if (cookie[i] != packet_get_char())
2207 packet_disconnect("IP Spoofing check bytes do not match.");
2209 debug("Encryption type: %.200s", cipher_name(cipher_type));
2211 /* Get the encrypted integer. */
2212 if ((session_key_int = BN_new()) == NULL)
2213 fatal("do_ssh1_kex: BN_new failed");
2214 packet_get_bignum(session_key_int);
2216 protocol_flags = packet_get_int();
2217 packet_set_protocol_flags(protocol_flags);
2220 /* Decrypt session_key_int using host/server keys */
2221 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2224 * Extract session key from the decrypted integer. The key is in the
2225 * least significant 256 bits of the integer; the first byte of the
2226 * key is in the highest bits.
2229 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2230 len = BN_num_bytes(session_key_int);
2231 if (len < 0 || (u_int)len > sizeof(session_key)) {
2232 error("do_ssh1_kex: bad session key len from %s: "
2233 "session_key_int %d > sizeof(session_key) %lu",
2234 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2237 memset(session_key, 0, sizeof(session_key));
2238 BN_bn2bin(session_key_int,
2239 session_key + sizeof(session_key) - len);
2241 derive_ssh1_session_id(
2242 sensitive_data.ssh1_host_key->rsa->n,
2243 sensitive_data.server_key->rsa->n,
2244 cookie, session_id);
2246 * Xor the first 16 bytes of the session key with the
2249 for (i = 0; i < 16; i++)
2250 session_key[i] ^= session_id[i];
2254 int bytes = BN_num_bytes(session_key_int);
2255 u_char *buf = xmalloc(bytes);
2258 logit("do_connection: generating a fake encryption key");
2259 BN_bn2bin(session_key_int, buf);
2261 MD5_Update(&md, buf, bytes);
2262 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2263 MD5_Final(session_key, &md);
2265 MD5_Update(&md, session_key, 16);
2266 MD5_Update(&md, buf, bytes);
2267 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2268 MD5_Final(session_key + 16, &md);
2269 memset(buf, 0, bytes);
2271 for (i = 0; i < 16; i++)
2272 session_id[i] = session_key[i] ^ session_key[i + 16];
2274 /* Destroy the private and public keys. No longer. */
2275 destroy_sensitive_data();
2278 mm_ssh1_session_id(session_id);
2280 /* Destroy the decrypted integer. It is no longer needed. */
2281 BN_clear_free(session_key_int);
2283 /* Set the session key. From this on all communications will be encrypted. */
2284 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2286 /* Destroy our copy of the session key. It is no longer needed. */
2287 memset(session_key, 0, sizeof(session_key));
2289 debug("Received session key; encryption turned on.");
2291 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2292 packet_start(SSH_SMSG_SUCCESS);
2294 packet_write_wait();
2298 * SSH2 key exchange: diffie-hellman-group1-sha1
2305 if (options.ciphers != NULL) {
2306 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2307 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2309 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2310 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2311 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2312 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2314 if (options.macs != NULL) {
2315 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2316 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2318 if (options.compression == COMP_NONE) {
2319 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2320 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2321 } else if (options.compression == COMP_DELAYED) {
2322 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2323 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2326 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2328 /* start key exchange */
2329 kex = kex_setup(myproposal);
2330 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2331 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2332 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2333 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2335 kex->client_version_string=client_version_string;
2336 kex->server_version_string=server_version_string;
2337 kex->load_host_public_key=&get_hostkey_public_by_type;
2338 kex->load_host_private_key=&get_hostkey_private_by_type;
2339 kex->host_key_index=&get_hostkey_index;
2343 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2345 session_id2 = kex->session_id;
2346 session_id2_len = kex->session_id_len;
2349 /* send 1st encrypted/maced/compressed message */
2350 packet_start(SSH2_MSG_IGNORE);
2351 packet_put_cstring("markus");
2353 packet_write_wait();
2358 /* server specific fatal cleanup */
2363 do_cleanup(the_authctxt);
2364 #ifdef SSH_AUDIT_EVENTS
2365 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2366 if (!use_privsep || mm_is_monitor())
2367 audit_event(SSH_CONNECTION_ABANDON);