1 /* $OpenBSD: sshd.c,v 1.375 2010/04/16 01:47:26 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.
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];
758 case KEY_RSA_CERT_V00:
759 case KEY_DSA_CERT_V00:
762 if (buffer_len(&b) > 0)
763 buffer_append(&b, ",", 1);
764 p = key_ssh_name(key);
765 buffer_append(&b, p, strlen(p));
769 buffer_append(&b, "\0", 1);
770 ret = xstrdup(buffer_ptr(&b));
772 debug("list_hostkey_types: %s", ret);
777 get_hostkey_by_type(int type, int need_private)
782 for (i = 0; i < options.num_host_key_files; i++) {
784 case KEY_RSA_CERT_V00:
785 case KEY_DSA_CERT_V00:
788 key = sensitive_data.host_certificates[i];
791 key = sensitive_data.host_keys[i];
794 if (key != NULL && key->type == type)
795 return need_private ?
796 sensitive_data.host_keys[i] : key;
802 get_hostkey_public_by_type(int type)
804 return get_hostkey_by_type(type, 0);
808 get_hostkey_private_by_type(int type)
810 return get_hostkey_by_type(type, 1);
814 get_hostkey_by_index(int ind)
816 if (ind < 0 || ind >= options.num_host_key_files)
818 return (sensitive_data.host_keys[ind]);
822 get_hostkey_index(Key *key)
826 for (i = 0; i < options.num_host_key_files; i++) {
827 if (key_is_cert(key)) {
828 if (key == sensitive_data.host_certificates[i])
831 if (key == sensitive_data.host_keys[i])
839 * returns 1 if connection should be dropped, 0 otherwise.
840 * dropping starts at connection #max_startups_begin with a probability
841 * of (max_startups_rate/100). the probability increases linearly until
842 * all connections are dropped for startups > max_startups
845 drop_connection(int startups)
849 if (startups < options.max_startups_begin)
851 if (startups >= options.max_startups)
853 if (options.max_startups_rate == 100)
856 p = 100 - options.max_startups_rate;
857 p *= startups - options.max_startups_begin;
858 p /= options.max_startups - options.max_startups_begin;
859 p += options.max_startups_rate;
860 r = arc4random_uniform(100);
862 debug("drop_connection: p %d, r %d", p, r);
863 return (r < p) ? 1 : 0;
869 fprintf(stderr, "%s, %s\n",
870 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
872 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
873 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
874 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
880 send_rexec_state(int fd, Buffer *conf)
884 debug3("%s: entering fd = %d config len %d", __func__, fd,
888 * Protocol from reexec master to child:
889 * string configuration
890 * u_int ephemeral_key_follows
891 * bignum e (only if ephemeral_key_follows == 1)
897 * string rngseed (only if OpenSSL is not self-seeded)
900 buffer_put_cstring(&m, buffer_ptr(conf));
902 if (sensitive_data.server_key != NULL &&
903 sensitive_data.server_key->type == KEY_RSA1) {
904 buffer_put_int(&m, 1);
905 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
906 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
907 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
908 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
909 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
910 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
912 buffer_put_int(&m, 0);
914 #ifndef OPENSSL_PRNG_ONLY
915 rexec_send_rng_seed(&m);
918 if (ssh_msg_send(fd, 0, &m) == -1)
919 fatal("%s: ssh_msg_send failed", __func__);
923 debug3("%s: done", __func__);
927 recv_rexec_state(int fd, Buffer *conf)
933 debug3("%s: entering fd = %d", __func__, fd);
937 if (ssh_msg_recv(fd, &m) == -1)
938 fatal("%s: ssh_msg_recv failed", __func__);
939 if (buffer_get_char(&m) != 0)
940 fatal("%s: rexec version mismatch", __func__);
942 cp = buffer_get_string(&m, &len);
944 buffer_append(conf, cp, len + 1);
947 if (buffer_get_int(&m)) {
948 if (sensitive_data.server_key != NULL)
949 key_free(sensitive_data.server_key);
950 sensitive_data.server_key = key_new_private(KEY_RSA1);
951 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
952 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
953 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
954 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
955 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
956 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
957 rsa_generate_additional_parameters(
958 sensitive_data.server_key->rsa);
961 #ifndef OPENSSL_PRNG_ONLY
962 rexec_recv_rng_seed(&m);
967 debug3("%s: done", __func__);
970 /* Accept a connection from inetd */
972 server_accept_inetd(int *sock_in, int *sock_out)
978 close(REEXEC_CONFIG_PASS_FD);
979 *sock_in = *sock_out = dup(STDIN_FILENO);
981 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
982 close(REEXEC_STARTUP_PIPE_FD);
985 *sock_in = dup(STDIN_FILENO);
986 *sock_out = dup(STDOUT_FILENO);
989 * We intentionally do not close the descriptors 0, 1, and 2
990 * as our code for setting the descriptors won't work if
991 * ttyfd happens to be one of those.
993 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
994 dup2(fd, STDIN_FILENO);
995 dup2(fd, STDOUT_FILENO);
996 if (fd > STDOUT_FILENO)
999 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1003 * Listen for TCP connections
1008 int ret, listen_sock, on = 1;
1009 struct addrinfo *ai;
1010 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1012 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1013 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1015 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1016 fatal("Too many listen sockets. "
1017 "Enlarge MAX_LISTEN_SOCKS");
1018 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1019 ntop, sizeof(ntop), strport, sizeof(strport),
1020 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1021 error("getnameinfo failed: %.100s",
1022 ssh_gai_strerror(ret));
1025 /* Create socket for listening. */
1026 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1028 if (listen_sock < 0) {
1029 /* kernel may not support ipv6 */
1030 verbose("socket: %.100s", strerror(errno));
1033 if (set_nonblock(listen_sock) == -1) {
1038 * Set socket options.
1039 * Allow local port reuse in TIME_WAIT.
1041 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1042 &on, sizeof(on)) == -1)
1043 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1045 /* Only communicate in IPv6 over AF_INET6 sockets. */
1046 if (ai->ai_family == AF_INET6)
1047 sock_set_v6only(listen_sock);
1049 debug("Bind to port %s on %s.", strport, ntop);
1051 /* Bind the socket to the desired port. */
1052 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1053 error("Bind to port %s on %s failed: %.200s.",
1054 strport, ntop, strerror(errno));
1058 listen_socks[num_listen_socks] = listen_sock;
1061 /* Start listening on the port. */
1062 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1063 fatal("listen on [%s]:%s: %.100s",
1064 ntop, strport, strerror(errno));
1065 logit("Server listening on %s port %s.", ntop, strport);
1067 freeaddrinfo(options.listen_addrs);
1069 if (!num_listen_socks)
1070 fatal("Cannot bind any address.");
1074 * The main TCP accept loop. Note that, for the non-debug case, returns
1075 * from this function are in a forked subprocess.
1078 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1081 int i, j, ret, maxfd;
1082 int key_used = 0, startups = 0;
1083 int startup_p[2] = { -1 , -1 };
1084 struct sockaddr_storage from;
1088 /* setup fd set for accept */
1091 for (i = 0; i < num_listen_socks; i++)
1092 if (listen_socks[i] > maxfd)
1093 maxfd = listen_socks[i];
1094 /* pipes connected to unauthenticated childs */
1095 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1096 for (i = 0; i < options.max_startups; i++)
1097 startup_pipes[i] = -1;
1100 * Stay listening for connections until the system crashes or
1101 * the daemon is killed with a signal.
1104 if (received_sighup)
1108 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1111 for (i = 0; i < num_listen_socks; i++)
1112 FD_SET(listen_socks[i], fdset);
1113 for (i = 0; i < options.max_startups; i++)
1114 if (startup_pipes[i] != -1)
1115 FD_SET(startup_pipes[i], fdset);
1117 /* Wait in select until there is a connection. */
1118 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1119 if (ret < 0 && errno != EINTR)
1120 error("select: %.100s", strerror(errno));
1121 if (received_sigterm) {
1122 logit("Received signal %d; terminating.",
1123 (int) received_sigterm);
1124 close_listen_socks();
1125 unlink(options.pid_file);
1128 if (key_used && key_do_regen) {
1129 generate_ephemeral_server_key();
1136 for (i = 0; i < options.max_startups; i++)
1137 if (startup_pipes[i] != -1 &&
1138 FD_ISSET(startup_pipes[i], fdset)) {
1140 * the read end of the pipe is ready
1141 * if the child has closed the pipe
1142 * after successful authentication
1143 * or if the child has died
1145 close(startup_pipes[i]);
1146 startup_pipes[i] = -1;
1149 for (i = 0; i < num_listen_socks; i++) {
1150 if (!FD_ISSET(listen_socks[i], fdset))
1152 fromlen = sizeof(from);
1153 *newsock = accept(listen_socks[i],
1154 (struct sockaddr *)&from, &fromlen);
1156 if (errno != EINTR && errno != EAGAIN &&
1157 errno != EWOULDBLOCK)
1158 error("accept: %.100s", strerror(errno));
1161 if (unset_nonblock(*newsock) == -1) {
1165 if (drop_connection(startups) == 1) {
1166 debug("drop connection #%d", startups);
1170 if (pipe(startup_p) == -1) {
1175 if (rexec_flag && socketpair(AF_UNIX,
1176 SOCK_STREAM, 0, config_s) == -1) {
1177 error("reexec socketpair: %s",
1180 close(startup_p[0]);
1181 close(startup_p[1]);
1185 for (j = 0; j < options.max_startups; j++)
1186 if (startup_pipes[j] == -1) {
1187 startup_pipes[j] = startup_p[0];
1188 if (maxfd < startup_p[0])
1189 maxfd = startup_p[0];
1195 * Got connection. Fork a child to handle it, unless
1196 * we are in debugging mode.
1200 * In debugging mode. Close the listening
1201 * socket, and start processing the
1202 * connection without forking.
1204 debug("Server will not fork when running in debugging mode.");
1205 close_listen_socks();
1206 *sock_in = *newsock;
1207 *sock_out = *newsock;
1208 close(startup_p[0]);
1209 close(startup_p[1]);
1213 send_rexec_state(config_s[0],
1221 * Normal production daemon. Fork, and have
1222 * the child process the connection. The
1223 * parent continues listening.
1225 platform_pre_fork();
1226 if ((pid = fork()) == 0) {
1228 * Child. Close the listening and
1229 * max_startup sockets. Start using
1230 * the accepted socket. Reinitialize
1231 * logging (since our pid has changed).
1232 * We break out of the loop to handle
1235 platform_post_fork_child();
1236 startup_pipe = startup_p[1];
1237 close_startup_pipes();
1238 close_listen_socks();
1239 *sock_in = *newsock;
1240 *sock_out = *newsock;
1241 log_init(__progname,
1243 options.log_facility,
1250 /* Parent. Stay in the loop. */
1251 platform_post_fork_parent(pid);
1253 error("fork: %.100s", strerror(errno));
1255 debug("Forked child %ld.", (long)pid);
1257 close(startup_p[1]);
1260 send_rexec_state(config_s[0], &cfg);
1266 * Mark that the key has been used (it
1267 * was "given" to the child).
1269 if ((options.protocol & SSH_PROTO_1) &&
1271 /* Schedule server key regeneration alarm. */
1272 signal(SIGALRM, key_regeneration_alarm);
1273 alarm(options.key_regeneration_time);
1280 * Ensure that our random state differs
1281 * from that of the child
1286 /* child process check (or debug mode) */
1287 if (num_listen_socks < 0)
1294 * Main program for the daemon.
1297 main(int ac, char **av)
1299 extern char *optarg;
1301 int opt, i, j, on = 1;
1302 int sock_in = -1, sock_out = -1, newsock = -1;
1303 const char *remote_ip;
1304 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1306 char *line, *p, *cp;
1307 int config_s[2] = { -1 , -1 };
1308 u_int64_t ibytes, obytes;
1313 #ifdef HAVE_SECUREWARE
1314 (void)set_auth_parameters(ac, av);
1316 __progname = ssh_get_progname(av[0]);
1319 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1322 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1323 for (i = 0; i < ac; i++)
1324 saved_argv[i] = xstrdup(av[i]);
1325 saved_argv[i] = NULL;
1327 #ifndef HAVE_SETPROCTITLE
1328 /* Prepare for later setproctitle emulation */
1329 compat_init_setproctitle(ac, av);
1333 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1334 debug("setgroups(): %.200s", strerror(errno));
1336 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1339 /* Initialize configuration options to their default values. */
1340 initialize_server_options(&options);
1342 /* Parse command-line arguments. */
1343 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1346 options.address_family = AF_INET;
1349 options.address_family = AF_INET6;
1352 config_file_name = optarg;
1355 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1356 fprintf(stderr, "too many host certificates.\n");
1359 options.host_cert_files[options.num_host_cert_files++] =
1360 derelativise_path(optarg);
1363 if (debug_flag == 0) {
1365 options.log_level = SYSLOG_LEVEL_DEBUG1;
1366 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1367 options.log_level++;
1389 options.log_level = SYSLOG_LEVEL_QUIET;
1392 options.server_key_bits = (int)strtonum(optarg, 256,
1396 options.ports_from_cmdline = 1;
1397 if (options.num_ports >= MAX_PORTS) {
1398 fprintf(stderr, "too many ports.\n");
1401 options.ports[options.num_ports++] = a2port(optarg);
1402 if (options.ports[options.num_ports-1] <= 0) {
1403 fprintf(stderr, "Bad port number.\n");
1408 if ((options.login_grace_time = convtime(optarg)) == -1) {
1409 fprintf(stderr, "Invalid login grace time.\n");
1414 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1415 fprintf(stderr, "Invalid key regeneration interval.\n");
1420 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1421 fprintf(stderr, "too many host keys.\n");
1424 options.host_key_files[options.num_host_key_files++] =
1425 derelativise_path(optarg);
1435 while ((p = strsep(&cp, ",")) && *p != '\0') {
1436 if (strncmp(p, "addr=", 5) == 0)
1437 test_addr = xstrdup(p + 5);
1438 else if (strncmp(p, "host=", 5) == 0)
1439 test_host = xstrdup(p + 5);
1440 else if (strncmp(p, "user=", 5) == 0)
1441 test_user = xstrdup(p + 5);
1443 fprintf(stderr, "Invalid test "
1444 "mode specification %s\n", p);
1450 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1451 if (utmp_len > MAXHOSTNAMELEN) {
1452 fprintf(stderr, "Invalid utmp length.\n");
1457 line = xstrdup(optarg);
1458 if (process_server_config_line(&options, line,
1459 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1469 if (rexeced_flag || inetd_flag)
1471 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1472 fatal("sshd re-exec requires execution with an absolute path");
1474 closefrom(REEXEC_MIN_FREE_FD);
1476 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1478 SSLeay_add_all_algorithms();
1481 * Force logging to stderr until we have loaded the private host
1482 * key (unless started from inetd)
1484 log_init(__progname,
1485 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1486 SYSLOG_LEVEL_INFO : options.log_level,
1487 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1488 SYSLOG_FACILITY_AUTH : options.log_facility,
1489 log_stderr || !inetd_flag);
1492 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1493 * root's environment
1495 if (getenv("KRB5CCNAME") != NULL)
1496 unsetenv("KRB5CCNAME");
1499 /* Cray can define user privs drop all privs now!
1500 * Not needed on PRIV_SU systems!
1505 sensitive_data.server_key = NULL;
1506 sensitive_data.ssh1_host_key = NULL;
1507 sensitive_data.have_ssh1_key = 0;
1508 sensitive_data.have_ssh2_key = 0;
1511 * If we're doing an extended config test, make sure we have all of
1512 * the parameters we need. If we're not doing an extended test,
1513 * do not silently ignore connection test params.
1515 if (test_flag >= 2 &&
1516 (test_user != NULL || test_host != NULL || test_addr != NULL)
1517 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1518 fatal("user, host and addr are all required when testing "
1520 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1522 fatal("Config test connection parameter (-C) provided without "
1525 /* Fetch our configuration */
1528 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1530 load_server_config(config_file_name, &cfg);
1532 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1533 &cfg, NULL, NULL, NULL);
1537 /* Fill in default values for those options not explicitly set. */
1538 fill_default_server_options(&options);
1540 /* challenge-response is implemented via keyboard interactive */
1541 if (options.challenge_response_authentication)
1542 options.kbd_interactive_authentication = 1;
1544 /* set default channel AF */
1545 channel_set_af(options.address_family);
1547 /* Check that there are no remaining arguments. */
1549 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1553 debug("sshd version %.100s", SSH_RELEASE);
1555 /* Store privilege separation user for later use if required. */
1556 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1557 if (use_privsep || options.kerberos_authentication)
1558 fatal("Privilege separation user %s does not exist",
1561 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1562 privsep_pw = pwcopy(privsep_pw);
1563 xfree(privsep_pw->pw_passwd);
1564 privsep_pw->pw_passwd = xstrdup("*");
1568 /* load private host keys */
1569 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1571 for (i = 0; i < options.num_host_key_files; i++)
1572 sensitive_data.host_keys[i] = NULL;
1574 for (i = 0; i < options.num_host_key_files; i++) {
1575 key = key_load_private(options.host_key_files[i], "", NULL);
1576 sensitive_data.host_keys[i] = key;
1578 error("Could not load host key: %s",
1579 options.host_key_files[i]);
1580 sensitive_data.host_keys[i] = NULL;
1583 switch (key->type) {
1585 sensitive_data.ssh1_host_key = key;
1586 sensitive_data.have_ssh1_key = 1;
1590 sensitive_data.have_ssh2_key = 1;
1593 debug("private host key: #%d type %d %s", i, key->type,
1596 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1597 logit("Disabling protocol version 1. Could not load host key");
1598 options.protocol &= ~SSH_PROTO_1;
1600 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1601 logit("Disabling protocol version 2. Could not load host key");
1602 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 /* Avoid killing the process in high-pressure swapping environments. */
1758 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0)
1759 debug("madvise(): %.200s", strerror(errno));
1761 /* Initialize the random number generator. */
1764 /* Chdir to the root directory so that the current disk can be
1765 unmounted if desired. */
1768 /* ignore SIGPIPE */
1769 signal(SIGPIPE, SIG_IGN);
1771 /* Get a connection, either from inetd or a listening TCP socket */
1773 server_accept_inetd(&sock_in, &sock_out);
1775 platform_pre_listen();
1778 if (options.protocol & SSH_PROTO_1)
1779 generate_ephemeral_server_key();
1781 signal(SIGHUP, sighup_handler);
1782 signal(SIGCHLD, main_sigchld_handler);
1783 signal(SIGTERM, sigterm_handler);
1784 signal(SIGQUIT, sigterm_handler);
1787 * Write out the pid file after the sigterm handler
1788 * is setup and the listen sockets are bound
1791 FILE *f = fopen(options.pid_file, "w");
1794 error("Couldn't create pid file \"%s\": %s",
1795 options.pid_file, strerror(errno));
1797 fprintf(f, "%ld\n", (long) getpid());
1802 /* Accept a connection and return in a forked child */
1803 server_accept_loop(&sock_in, &sock_out,
1804 &newsock, config_s);
1807 /* This is the child processing a new connection. */
1808 setproctitle("%s", "[accepted]");
1811 * Create a new session and process group since the 4.4BSD
1812 * setlogin() affects the entire process group. We don't
1813 * want the child to be able to affect the parent.
1815 #if !defined(SSHD_ACQUIRES_CTTY)
1817 * If setsid is called, on some platforms sshd will later acquire a
1818 * controlling terminal which will result in "could not set
1819 * controlling tty" errors.
1821 if (!debug_flag && !inetd_flag && setsid() < 0)
1822 error("setsid: %.100s", strerror(errno));
1828 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1829 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1830 dup2(newsock, STDIN_FILENO);
1831 dup2(STDIN_FILENO, STDOUT_FILENO);
1832 if (startup_pipe == -1)
1833 close(REEXEC_STARTUP_PIPE_FD);
1835 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1837 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1839 if (startup_pipe != -1)
1840 close(startup_pipe);
1842 execv(rexec_argv[0], rexec_argv);
1844 /* Reexec has failed, fall back and continue */
1845 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1846 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1847 log_init(__progname, options.log_level,
1848 options.log_facility, log_stderr);
1851 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1853 close(REEXEC_CONFIG_PASS_FD);
1854 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1855 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1856 dup2(fd, STDIN_FILENO);
1857 dup2(fd, STDOUT_FILENO);
1858 if (fd > STDERR_FILENO)
1861 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1862 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1865 /* Executed child processes don't need these. */
1866 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1867 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1870 * Disable the key regeneration alarm. We will not regenerate the
1871 * key since we are no longer in a position to give it to anyone. We
1872 * will not restart on SIGHUP since it no longer makes sense.
1875 signal(SIGALRM, SIG_DFL);
1876 signal(SIGHUP, SIG_DFL);
1877 signal(SIGTERM, SIG_DFL);
1878 signal(SIGQUIT, SIG_DFL);
1879 signal(SIGCHLD, SIG_DFL);
1880 signal(SIGINT, SIG_DFL);
1884 * Initialize the resolver. This may not happen automatically
1885 * before privsep chroot().
1887 if ((_res.options & RES_INIT) == 0) {
1888 debug("res_init()");
1893 * Force GSS-API to parse its configuration and load any
1894 * mechanism plugins.
1898 OM_uint32 minor_status;
1899 gss_indicate_mechs(&minor_status, &mechs);
1900 gss_release_oid_set(&minor_status, &mechs);
1906 * Register our connection. This turns encryption off because we do
1909 packet_set_connection(sock_in, sock_out);
1910 packet_set_server();
1912 /* Set SO_KEEPALIVE if requested. */
1913 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1914 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1915 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1917 if ((remote_port = get_remote_port()) < 0) {
1918 debug("get_remote_port failed");
1923 * We use get_canonical_hostname with usedns = 0 instead of
1924 * get_remote_ipaddr here so IP options will be checked.
1926 (void) get_canonical_hostname(0);
1928 * The rest of the code depends on the fact that
1929 * get_remote_ipaddr() caches the remote ip, even if
1930 * the socket goes away.
1932 remote_ip = get_remote_ipaddr();
1934 #ifdef SSH_AUDIT_EVENTS
1935 audit_connection_from(remote_ip, remote_port);
1938 allow_severity = options.log_facility|LOG_INFO;
1939 deny_severity = options.log_facility|LOG_WARNING;
1940 /* Check whether logins are denied from this host. */
1941 if (packet_connection_is_on_socket()) {
1942 struct request_info req;
1944 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1947 if (!hosts_access(&req)) {
1948 debug("Connection refused by tcp wrapper");
1951 fatal("libwrap refuse returns");
1954 #endif /* LIBWRAP */
1956 /* Log the connection. */
1957 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1960 * We don't want to listen forever unless the other side
1961 * successfully authenticates itself. So we set up an alarm which is
1962 * cleared after successful authentication. A limit of zero
1963 * indicates no limit. Note that we don't set the alarm in debugging
1964 * mode; it is just annoying to have the server exit just when you
1965 * are about to discover the bug.
1967 signal(SIGALRM, grace_alarm_handler);
1969 alarm(options.login_grace_time);
1971 sshd_exchange_identification(sock_in, sock_out);
1973 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1974 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1975 generate_ephemeral_server_key();
1977 packet_set_nonblocking();
1979 /* allocate authentication context */
1980 authctxt = xcalloc(1, sizeof(*authctxt));
1982 authctxt->loginmsg = &loginmsg;
1984 /* XXX global for cleanup, access from other modules */
1985 the_authctxt = authctxt;
1987 /* prepare buffer to collect messages to display to user after login */
1988 buffer_init(&loginmsg);
1992 if (privsep_preauth(authctxt) == 1)
1995 /* perform the key exchange */
1996 /* authenticate user and start session */
1999 do_authentication2(authctxt);
2002 do_authentication(authctxt);
2005 * If we use privilege separation, the unprivileged child transfers
2006 * the current keystate and exits
2009 mm_send_keystate(pmonitor);
2015 * Cancel the alarm we set to limit the time taken for
2019 signal(SIGALRM, SIG_DFL);
2020 authctxt->authenticated = 1;
2021 if (startup_pipe != -1) {
2022 close(startup_pipe);
2026 #ifdef SSH_AUDIT_EVENTS
2027 audit_event(SSH_AUTH_SUCCESS);
2031 if (options.gss_authentication) {
2032 temporarily_use_uid(authctxt->pw);
2033 ssh_gssapi_storecreds();
2038 if (options.use_pam) {
2045 * In privilege separation, we fork another child and prepare
2046 * file descriptor passing.
2049 privsep_postauth(authctxt);
2050 /* the monitor process [priv] will not return */
2052 destroy_sensitive_data();
2055 packet_set_timeout(options.client_alive_interval,
2056 options.client_alive_count_max);
2058 /* Start session. */
2059 do_authenticated(authctxt);
2061 /* The connection has been terminated. */
2062 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2063 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2064 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
2066 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2069 if (options.use_pam)
2071 #endif /* USE_PAM */
2073 #ifdef SSH_AUDIT_EVENTS
2074 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2086 * Decrypt session_key_int using our private server key and private host key
2087 * (key with larger modulus first).
2090 ssh1_session_key(BIGNUM *session_key_int)
2094 if (BN_cmp(sensitive_data.server_key->rsa->n,
2095 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2096 /* Server key has bigger modulus. */
2097 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2098 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2099 SSH_KEY_BITS_RESERVED) {
2100 fatal("do_connection: %s: "
2101 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2102 get_remote_ipaddr(),
2103 BN_num_bits(sensitive_data.server_key->rsa->n),
2104 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2105 SSH_KEY_BITS_RESERVED);
2107 if (rsa_private_decrypt(session_key_int, session_key_int,
2108 sensitive_data.server_key->rsa) <= 0)
2110 if (rsa_private_decrypt(session_key_int, session_key_int,
2111 sensitive_data.ssh1_host_key->rsa) <= 0)
2114 /* Host key has bigger modulus (or they are equal). */
2115 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2116 BN_num_bits(sensitive_data.server_key->rsa->n) +
2117 SSH_KEY_BITS_RESERVED) {
2118 fatal("do_connection: %s: "
2119 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2120 get_remote_ipaddr(),
2121 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2122 BN_num_bits(sensitive_data.server_key->rsa->n),
2123 SSH_KEY_BITS_RESERVED);
2125 if (rsa_private_decrypt(session_key_int, session_key_int,
2126 sensitive_data.ssh1_host_key->rsa) < 0)
2128 if (rsa_private_decrypt(session_key_int, session_key_int,
2129 sensitive_data.server_key->rsa) < 0)
2142 BIGNUM *session_key_int;
2143 u_char session_key[SSH_SESSION_KEY_LENGTH];
2145 u_int cipher_type, auth_mask, protocol_flags;
2148 * Generate check bytes that the client must send back in the user
2149 * packet in order for it to be accepted; this is used to defy ip
2150 * spoofing attacks. Note that this only works against somebody
2151 * doing IP spoofing from a remote machine; any machine on the local
2152 * network can still see outgoing packets and catch the random
2153 * cookie. This only affects rhosts authentication, and this is one
2154 * of the reasons why it is inherently insecure.
2156 arc4random_buf(cookie, sizeof(cookie));
2159 * Send our public key. We include in the packet 64 bits of random
2160 * data that must be matched in the reply in order to prevent IP
2163 packet_start(SSH_SMSG_PUBLIC_KEY);
2164 for (i = 0; i < 8; i++)
2165 packet_put_char(cookie[i]);
2167 /* Store our public server RSA key. */
2168 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2169 packet_put_bignum(sensitive_data.server_key->rsa->e);
2170 packet_put_bignum(sensitive_data.server_key->rsa->n);
2172 /* Store our public host RSA key. */
2173 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2174 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2175 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2177 /* Put protocol flags. */
2178 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2180 /* Declare which ciphers we support. */
2181 packet_put_int(cipher_mask_ssh1(0));
2183 /* Declare supported authentication types. */
2185 if (options.rhosts_rsa_authentication)
2186 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2187 if (options.rsa_authentication)
2188 auth_mask |= 1 << SSH_AUTH_RSA;
2189 if (options.challenge_response_authentication == 1)
2190 auth_mask |= 1 << SSH_AUTH_TIS;
2191 if (options.password_authentication)
2192 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2193 packet_put_int(auth_mask);
2195 /* Send the packet and wait for it to be sent. */
2197 packet_write_wait();
2199 debug("Sent %d bit server key and %d bit host key.",
2200 BN_num_bits(sensitive_data.server_key->rsa->n),
2201 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2203 /* Read clients reply (cipher type and session key). */
2204 packet_read_expect(SSH_CMSG_SESSION_KEY);
2206 /* Get cipher type and check whether we accept this. */
2207 cipher_type = packet_get_char();
2209 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2210 packet_disconnect("Warning: client selects unsupported cipher.");
2212 /* Get check bytes from the packet. These must match those we
2213 sent earlier with the public key packet. */
2214 for (i = 0; i < 8; i++)
2215 if (cookie[i] != packet_get_char())
2216 packet_disconnect("IP Spoofing check bytes do not match.");
2218 debug("Encryption type: %.200s", cipher_name(cipher_type));
2220 /* Get the encrypted integer. */
2221 if ((session_key_int = BN_new()) == NULL)
2222 fatal("do_ssh1_kex: BN_new failed");
2223 packet_get_bignum(session_key_int);
2225 protocol_flags = packet_get_int();
2226 packet_set_protocol_flags(protocol_flags);
2229 /* Decrypt session_key_int using host/server keys */
2230 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2233 * Extract session key from the decrypted integer. The key is in the
2234 * least significant 256 bits of the integer; the first byte of the
2235 * key is in the highest bits.
2238 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2239 len = BN_num_bytes(session_key_int);
2240 if (len < 0 || (u_int)len > sizeof(session_key)) {
2241 error("do_ssh1_kex: bad session key len from %s: "
2242 "session_key_int %d > sizeof(session_key) %lu",
2243 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2246 memset(session_key, 0, sizeof(session_key));
2247 BN_bn2bin(session_key_int,
2248 session_key + sizeof(session_key) - len);
2250 derive_ssh1_session_id(
2251 sensitive_data.ssh1_host_key->rsa->n,
2252 sensitive_data.server_key->rsa->n,
2253 cookie, session_id);
2255 * Xor the first 16 bytes of the session key with the
2258 for (i = 0; i < 16; i++)
2259 session_key[i] ^= session_id[i];
2263 int bytes = BN_num_bytes(session_key_int);
2264 u_char *buf = xmalloc(bytes);
2267 logit("do_connection: generating a fake encryption key");
2268 BN_bn2bin(session_key_int, buf);
2270 MD5_Update(&md, buf, bytes);
2271 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2272 MD5_Final(session_key, &md);
2274 MD5_Update(&md, session_key, 16);
2275 MD5_Update(&md, buf, bytes);
2276 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2277 MD5_Final(session_key + 16, &md);
2278 memset(buf, 0, bytes);
2280 for (i = 0; i < 16; i++)
2281 session_id[i] = session_key[i] ^ session_key[i + 16];
2283 /* Destroy the private and public keys. No longer. */
2284 destroy_sensitive_data();
2287 mm_ssh1_session_id(session_id);
2289 /* Destroy the decrypted integer. It is no longer needed. */
2290 BN_clear_free(session_key_int);
2292 /* Set the session key. From this on all communications will be encrypted. */
2293 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2295 /* Destroy our copy of the session key. It is no longer needed. */
2296 memset(session_key, 0, sizeof(session_key));
2298 debug("Received session key; encryption turned on.");
2300 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2301 packet_start(SSH_SMSG_SUCCESS);
2303 packet_write_wait();
2307 * SSH2 key exchange: diffie-hellman-group1-sha1
2314 if (options.ciphers != NULL) {
2315 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2316 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2318 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2319 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2320 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2321 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2323 if (options.macs != NULL) {
2324 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2325 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2327 if (options.compression == COMP_NONE) {
2328 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2329 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2330 } else if (options.compression == COMP_DELAYED) {
2331 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2332 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2335 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2337 /* start key exchange */
2338 kex = kex_setup(myproposal);
2339 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2340 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2341 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2342 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2344 kex->client_version_string=client_version_string;
2345 kex->server_version_string=server_version_string;
2346 kex->load_host_public_key=&get_hostkey_public_by_type;
2347 kex->load_host_private_key=&get_hostkey_private_by_type;
2348 kex->host_key_index=&get_hostkey_index;
2352 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2354 session_id2 = kex->session_id;
2355 session_id2_len = kex->session_id_len;
2358 /* send 1st encrypted/maced/compressed message */
2359 packet_start(SSH2_MSG_IGNORE);
2360 packet_put_cstring("markus");
2362 packet_write_wait();
2367 /* server specific fatal cleanup */
2372 do_cleanup(the_authctxt);
2373 #ifdef SSH_AUDIT_EVENTS
2374 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2375 if (!use_privsep || mm_is_monitor())
2376 audit_event(SSH_CONNECTION_ABANDON);