1 /* $OpenBSD: sshd.c,v 1.381 2011/01/11 06:13:10 djm Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This program is the ssh daemon. It listens for connections from clients,
7 * and performs authentication, executes use commands or shell, and forwards
8 * information to/from the application to the user client over an encrypted
9 * connection. This can also handle forwarding of X11, TCP/IP, and
10 * authentication agent connections.
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
18 * SSH2 implementation:
19 * Privilege Separation:
21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22 * Copyright (c) 2002 Niels Provos. All rights reserved.
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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];
748 if (buffer_len(&b) > 0)
749 buffer_append(&b, ",", 1);
750 p = key_ssh_name(key);
751 buffer_append(&b, p, strlen(p));
754 /* If the private key has a cert peer, then list that too */
755 key = sensitive_data.host_certificates[i];
759 case KEY_RSA_CERT_V00:
760 case KEY_DSA_CERT_V00:
764 if (buffer_len(&b) > 0)
765 buffer_append(&b, ",", 1);
766 p = key_ssh_name(key);
767 buffer_append(&b, p, strlen(p));
771 buffer_append(&b, "\0", 1);
772 ret = xstrdup(buffer_ptr(&b));
774 debug("list_hostkey_types: %s", ret);
779 get_hostkey_by_type(int type, int need_private)
784 for (i = 0; i < options.num_host_key_files; i++) {
786 case KEY_RSA_CERT_V00:
787 case KEY_DSA_CERT_V00:
791 key = sensitive_data.host_certificates[i];
794 key = sensitive_data.host_keys[i];
797 if (key != NULL && key->type == type)
798 return need_private ?
799 sensitive_data.host_keys[i] : key;
805 get_hostkey_public_by_type(int type)
807 return get_hostkey_by_type(type, 0);
811 get_hostkey_private_by_type(int type)
813 return get_hostkey_by_type(type, 1);
817 get_hostkey_by_index(int ind)
819 if (ind < 0 || ind >= options.num_host_key_files)
821 return (sensitive_data.host_keys[ind]);
825 get_hostkey_index(Key *key)
829 for (i = 0; i < options.num_host_key_files; i++) {
830 if (key_is_cert(key)) {
831 if (key == sensitive_data.host_certificates[i])
834 if (key == sensitive_data.host_keys[i])
842 * returns 1 if connection should be dropped, 0 otherwise.
843 * dropping starts at connection #max_startups_begin with a probability
844 * of (max_startups_rate/100). the probability increases linearly until
845 * all connections are dropped for startups > max_startups
848 drop_connection(int startups)
852 if (startups < options.max_startups_begin)
854 if (startups >= options.max_startups)
856 if (options.max_startups_rate == 100)
859 p = 100 - options.max_startups_rate;
860 p *= startups - options.max_startups_begin;
861 p /= options.max_startups - options.max_startups_begin;
862 p += options.max_startups_rate;
863 r = arc4random_uniform(100);
865 debug("drop_connection: p %d, r %d", p, r);
866 return (r < p) ? 1 : 0;
872 fprintf(stderr, "%s, %s\n",
873 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
875 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
876 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
877 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
883 send_rexec_state(int fd, Buffer *conf)
887 debug3("%s: entering fd = %d config len %d", __func__, fd,
891 * Protocol from reexec master to child:
892 * string configuration
893 * u_int ephemeral_key_follows
894 * bignum e (only if ephemeral_key_follows == 1)
900 * string rngseed (only if OpenSSL is not self-seeded)
903 buffer_put_cstring(&m, buffer_ptr(conf));
905 if (sensitive_data.server_key != NULL &&
906 sensitive_data.server_key->type == KEY_RSA1) {
907 buffer_put_int(&m, 1);
908 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
909 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
910 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
911 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
912 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
913 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
915 buffer_put_int(&m, 0);
917 #ifndef OPENSSL_PRNG_ONLY
918 rexec_send_rng_seed(&m);
921 if (ssh_msg_send(fd, 0, &m) == -1)
922 fatal("%s: ssh_msg_send failed", __func__);
926 debug3("%s: done", __func__);
930 recv_rexec_state(int fd, Buffer *conf)
936 debug3("%s: entering fd = %d", __func__, fd);
940 if (ssh_msg_recv(fd, &m) == -1)
941 fatal("%s: ssh_msg_recv failed", __func__);
942 if (buffer_get_char(&m) != 0)
943 fatal("%s: rexec version mismatch", __func__);
945 cp = buffer_get_string(&m, &len);
947 buffer_append(conf, cp, len + 1);
950 if (buffer_get_int(&m)) {
951 if (sensitive_data.server_key != NULL)
952 key_free(sensitive_data.server_key);
953 sensitive_data.server_key = key_new_private(KEY_RSA1);
954 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
955 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
956 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
957 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
958 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
959 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
960 rsa_generate_additional_parameters(
961 sensitive_data.server_key->rsa);
964 #ifndef OPENSSL_PRNG_ONLY
965 rexec_recv_rng_seed(&m);
970 debug3("%s: done", __func__);
973 /* Accept a connection from inetd */
975 server_accept_inetd(int *sock_in, int *sock_out)
981 close(REEXEC_CONFIG_PASS_FD);
982 *sock_in = *sock_out = dup(STDIN_FILENO);
984 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
985 close(REEXEC_STARTUP_PIPE_FD);
988 *sock_in = dup(STDIN_FILENO);
989 *sock_out = dup(STDOUT_FILENO);
992 * We intentionally do not close the descriptors 0, 1, and 2
993 * as our code for setting the descriptors won't work if
994 * ttyfd happens to be one of those.
996 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
997 dup2(fd, STDIN_FILENO);
998 dup2(fd, STDOUT_FILENO);
999 if (fd > STDOUT_FILENO)
1002 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1006 * Listen for TCP connections
1011 int ret, listen_sock, on = 1;
1012 struct addrinfo *ai;
1013 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1015 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1016 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1018 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1019 fatal("Too many listen sockets. "
1020 "Enlarge MAX_LISTEN_SOCKS");
1021 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1022 ntop, sizeof(ntop), strport, sizeof(strport),
1023 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1024 error("getnameinfo failed: %.100s",
1025 ssh_gai_strerror(ret));
1028 /* Create socket for listening. */
1029 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1031 if (listen_sock < 0) {
1032 /* kernel may not support ipv6 */
1033 verbose("socket: %.100s", strerror(errno));
1036 if (set_nonblock(listen_sock) == -1) {
1041 * Set socket options.
1042 * Allow local port reuse in TIME_WAIT.
1044 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1045 &on, sizeof(on)) == -1)
1046 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1048 /* Only communicate in IPv6 over AF_INET6 sockets. */
1049 if (ai->ai_family == AF_INET6)
1050 sock_set_v6only(listen_sock);
1052 debug("Bind to port %s on %s.", strport, ntop);
1054 /* Bind the socket to the desired port. */
1055 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1056 error("Bind to port %s on %s failed: %.200s.",
1057 strport, ntop, strerror(errno));
1061 listen_socks[num_listen_socks] = listen_sock;
1064 /* Start listening on the port. */
1065 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1066 fatal("listen on [%s]:%s: %.100s",
1067 ntop, strport, strerror(errno));
1068 logit("Server listening on %s port %s.", ntop, strport);
1070 freeaddrinfo(options.listen_addrs);
1072 if (!num_listen_socks)
1073 fatal("Cannot bind any address.");
1077 * The main TCP accept loop. Note that, for the non-debug case, returns
1078 * from this function are in a forked subprocess.
1081 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1084 int i, j, ret, maxfd;
1085 int key_used = 0, startups = 0;
1086 int startup_p[2] = { -1 , -1 };
1087 struct sockaddr_storage from;
1091 /* setup fd set for accept */
1094 for (i = 0; i < num_listen_socks; i++)
1095 if (listen_socks[i] > maxfd)
1096 maxfd = listen_socks[i];
1097 /* pipes connected to unauthenticated childs */
1098 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1099 for (i = 0; i < options.max_startups; i++)
1100 startup_pipes[i] = -1;
1103 * Stay listening for connections until the system crashes or
1104 * the daemon is killed with a signal.
1107 if (received_sighup)
1111 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1114 for (i = 0; i < num_listen_socks; i++)
1115 FD_SET(listen_socks[i], fdset);
1116 for (i = 0; i < options.max_startups; i++)
1117 if (startup_pipes[i] != -1)
1118 FD_SET(startup_pipes[i], fdset);
1120 /* Wait in select until there is a connection. */
1121 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1122 if (ret < 0 && errno != EINTR)
1123 error("select: %.100s", strerror(errno));
1124 if (received_sigterm) {
1125 logit("Received signal %d; terminating.",
1126 (int) received_sigterm);
1127 close_listen_socks();
1128 unlink(options.pid_file);
1131 if (key_used && key_do_regen) {
1132 generate_ephemeral_server_key();
1139 for (i = 0; i < options.max_startups; i++)
1140 if (startup_pipes[i] != -1 &&
1141 FD_ISSET(startup_pipes[i], fdset)) {
1143 * the read end of the pipe is ready
1144 * if the child has closed the pipe
1145 * after successful authentication
1146 * or if the child has died
1148 close(startup_pipes[i]);
1149 startup_pipes[i] = -1;
1152 for (i = 0; i < num_listen_socks; i++) {
1153 if (!FD_ISSET(listen_socks[i], fdset))
1155 fromlen = sizeof(from);
1156 *newsock = accept(listen_socks[i],
1157 (struct sockaddr *)&from, &fromlen);
1159 if (errno != EINTR && errno != EAGAIN &&
1160 errno != EWOULDBLOCK)
1161 error("accept: %.100s", strerror(errno));
1164 if (unset_nonblock(*newsock) == -1) {
1168 if (drop_connection(startups) == 1) {
1169 debug("drop connection #%d", startups);
1173 if (pipe(startup_p) == -1) {
1178 if (rexec_flag && socketpair(AF_UNIX,
1179 SOCK_STREAM, 0, config_s) == -1) {
1180 error("reexec socketpair: %s",
1183 close(startup_p[0]);
1184 close(startup_p[1]);
1188 for (j = 0; j < options.max_startups; j++)
1189 if (startup_pipes[j] == -1) {
1190 startup_pipes[j] = startup_p[0];
1191 if (maxfd < startup_p[0])
1192 maxfd = startup_p[0];
1198 * Got connection. Fork a child to handle it, unless
1199 * we are in debugging mode.
1203 * In debugging mode. Close the listening
1204 * socket, and start processing the
1205 * connection without forking.
1207 debug("Server will not fork when running in debugging mode.");
1208 close_listen_socks();
1209 *sock_in = *newsock;
1210 *sock_out = *newsock;
1211 close(startup_p[0]);
1212 close(startup_p[1]);
1216 send_rexec_state(config_s[0],
1224 * Normal production daemon. Fork, and have
1225 * the child process the connection. The
1226 * parent continues listening.
1228 platform_pre_fork();
1229 if ((pid = fork()) == 0) {
1231 * Child. Close the listening and
1232 * max_startup sockets. Start using
1233 * the accepted socket. Reinitialize
1234 * logging (since our pid has changed).
1235 * We break out of the loop to handle
1238 platform_post_fork_child();
1239 startup_pipe = startup_p[1];
1240 close_startup_pipes();
1241 close_listen_socks();
1242 *sock_in = *newsock;
1243 *sock_out = *newsock;
1244 log_init(__progname,
1246 options.log_facility,
1253 /* Parent. Stay in the loop. */
1254 platform_post_fork_parent(pid);
1256 error("fork: %.100s", strerror(errno));
1258 debug("Forked child %ld.", (long)pid);
1260 close(startup_p[1]);
1263 send_rexec_state(config_s[0], &cfg);
1269 * Mark that the key has been used (it
1270 * was "given" to the child).
1272 if ((options.protocol & SSH_PROTO_1) &&
1274 /* Schedule server key regeneration alarm. */
1275 signal(SIGALRM, key_regeneration_alarm);
1276 alarm(options.key_regeneration_time);
1283 * Ensure that our random state differs
1284 * from that of the child
1289 /* child process check (or debug mode) */
1290 if (num_listen_socks < 0)
1297 * Main program for the daemon.
1300 main(int ac, char **av)
1302 extern char *optarg;
1304 int opt, i, j, on = 1;
1305 int sock_in = -1, sock_out = -1, newsock = -1;
1306 const char *remote_ip;
1307 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1309 char *line, *p, *cp;
1310 int config_s[2] = { -1 , -1 };
1311 u_int64_t ibytes, obytes;
1316 #ifdef HAVE_SECUREWARE
1317 (void)set_auth_parameters(ac, av);
1319 __progname = ssh_get_progname(av[0]);
1322 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1325 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1326 for (i = 0; i < ac; i++)
1327 saved_argv[i] = xstrdup(av[i]);
1328 saved_argv[i] = NULL;
1330 #ifndef HAVE_SETPROCTITLE
1331 /* Prepare for later setproctitle emulation */
1332 compat_init_setproctitle(ac, av);
1336 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1337 debug("setgroups(): %.200s", strerror(errno));
1339 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1342 /* Initialize configuration options to their default values. */
1343 initialize_server_options(&options);
1345 /* Parse command-line arguments. */
1346 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1349 options.address_family = AF_INET;
1352 options.address_family = AF_INET6;
1355 config_file_name = optarg;
1358 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1359 fprintf(stderr, "too many host certificates.\n");
1362 options.host_cert_files[options.num_host_cert_files++] =
1363 derelativise_path(optarg);
1366 if (debug_flag == 0) {
1368 options.log_level = SYSLOG_LEVEL_DEBUG1;
1369 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1370 options.log_level++;
1392 options.log_level = SYSLOG_LEVEL_QUIET;
1395 options.server_key_bits = (int)strtonum(optarg, 256,
1399 options.ports_from_cmdline = 1;
1400 if (options.num_ports >= MAX_PORTS) {
1401 fprintf(stderr, "too many ports.\n");
1404 options.ports[options.num_ports++] = a2port(optarg);
1405 if (options.ports[options.num_ports-1] <= 0) {
1406 fprintf(stderr, "Bad port number.\n");
1411 if ((options.login_grace_time = convtime(optarg)) == -1) {
1412 fprintf(stderr, "Invalid login grace time.\n");
1417 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1418 fprintf(stderr, "Invalid key regeneration interval.\n");
1423 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1424 fprintf(stderr, "too many host keys.\n");
1427 options.host_key_files[options.num_host_key_files++] =
1428 derelativise_path(optarg);
1438 while ((p = strsep(&cp, ",")) && *p != '\0') {
1439 if (strncmp(p, "addr=", 5) == 0)
1440 test_addr = xstrdup(p + 5);
1441 else if (strncmp(p, "host=", 5) == 0)
1442 test_host = xstrdup(p + 5);
1443 else if (strncmp(p, "user=", 5) == 0)
1444 test_user = xstrdup(p + 5);
1446 fprintf(stderr, "Invalid test "
1447 "mode specification %s\n", p);
1453 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1454 if (utmp_len > MAXHOSTNAMELEN) {
1455 fprintf(stderr, "Invalid utmp length.\n");
1460 line = xstrdup(optarg);
1461 if (process_server_config_line(&options, line,
1462 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1472 if (rexeced_flag || inetd_flag)
1474 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1475 fatal("sshd re-exec requires execution with an absolute path");
1477 closefrom(REEXEC_MIN_FREE_FD);
1479 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1481 OpenSSL_add_all_algorithms();
1484 * Force logging to stderr until we have loaded the private host
1485 * key (unless started from inetd)
1487 log_init(__progname,
1488 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1489 SYSLOG_LEVEL_INFO : options.log_level,
1490 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1491 SYSLOG_FACILITY_AUTH : options.log_facility,
1492 log_stderr || !inetd_flag);
1495 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1496 * root's environment
1498 if (getenv("KRB5CCNAME") != NULL)
1499 unsetenv("KRB5CCNAME");
1502 /* Cray can define user privs drop all privs now!
1503 * Not needed on PRIV_SU systems!
1508 sensitive_data.server_key = NULL;
1509 sensitive_data.ssh1_host_key = NULL;
1510 sensitive_data.have_ssh1_key = 0;
1511 sensitive_data.have_ssh2_key = 0;
1514 * If we're doing an extended config test, make sure we have all of
1515 * the parameters we need. If we're not doing an extended test,
1516 * do not silently ignore connection test params.
1518 if (test_flag >= 2 &&
1519 (test_user != NULL || test_host != NULL || test_addr != NULL)
1520 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1521 fatal("user, host and addr are all required when testing "
1523 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1525 fatal("Config test connection parameter (-C) provided without "
1528 /* Fetch our configuration */
1531 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1533 load_server_config(config_file_name, &cfg);
1535 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1536 &cfg, NULL, NULL, NULL);
1540 /* Fill in default values for those options not explicitly set. */
1541 fill_default_server_options(&options);
1543 /* challenge-response is implemented via keyboard interactive */
1544 if (options.challenge_response_authentication)
1545 options.kbd_interactive_authentication = 1;
1547 /* set default channel AF */
1548 channel_set_af(options.address_family);
1550 /* Check that there are no remaining arguments. */
1552 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1556 debug("sshd version %.100s", SSH_RELEASE);
1558 /* Store privilege separation user for later use if required. */
1559 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1560 if (use_privsep || options.kerberos_authentication)
1561 fatal("Privilege separation user %s does not exist",
1564 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1565 privsep_pw = pwcopy(privsep_pw);
1566 xfree(privsep_pw->pw_passwd);
1567 privsep_pw->pw_passwd = xstrdup("*");
1571 /* load private host keys */
1572 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1574 for (i = 0; i < options.num_host_key_files; i++)
1575 sensitive_data.host_keys[i] = NULL;
1577 for (i = 0; i < options.num_host_key_files; i++) {
1578 key = key_load_private(options.host_key_files[i], "", NULL);
1579 sensitive_data.host_keys[i] = key;
1581 error("Could not load host key: %s",
1582 options.host_key_files[i]);
1583 sensitive_data.host_keys[i] = NULL;
1586 switch (key->type) {
1588 sensitive_data.ssh1_host_key = key;
1589 sensitive_data.have_ssh1_key = 1;
1594 sensitive_data.have_ssh2_key = 1;
1597 debug("private host key: #%d type %d %s", i, key->type,
1600 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1601 logit("Disabling protocol version 1. Could not load host key");
1602 options.protocol &= ~SSH_PROTO_1;
1604 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1605 logit("Disabling protocol version 2. Could not load host key");
1606 options.protocol &= ~SSH_PROTO_2;
1608 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1609 logit("sshd: no hostkeys available -- exiting.");
1614 * Load certificates. They are stored in an array at identical
1615 * indices to the public keys that they relate to.
1617 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1619 for (i = 0; i < options.num_host_key_files; i++)
1620 sensitive_data.host_certificates[i] = NULL;
1622 for (i = 0; i < options.num_host_cert_files; i++) {
1623 key = key_load_public(options.host_cert_files[i], NULL);
1625 error("Could not load host certificate: %s",
1626 options.host_cert_files[i]);
1629 if (!key_is_cert(key)) {
1630 error("Certificate file is not a certificate: %s",
1631 options.host_cert_files[i]);
1635 /* Find matching private key */
1636 for (j = 0; j < options.num_host_key_files; j++) {
1637 if (key_equal_public(key,
1638 sensitive_data.host_keys[j])) {
1639 sensitive_data.host_certificates[j] = key;
1643 if (j >= options.num_host_key_files) {
1644 error("No matching private key for certificate: %s",
1645 options.host_cert_files[i]);
1649 sensitive_data.host_certificates[j] = key;
1650 debug("host certificate: #%d type %d %s", j, key->type,
1653 /* Check certain values for sanity. */
1654 if (options.protocol & SSH_PROTO_1) {
1655 if (options.server_key_bits < 512 ||
1656 options.server_key_bits > 32768) {
1657 fprintf(stderr, "Bad server key size.\n");
1661 * Check that server and host key lengths differ sufficiently. This
1662 * is necessary to make double encryption work with rsaref. Oh, I
1663 * hate software patents. I dont know if this can go? Niels
1665 if (options.server_key_bits >
1666 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1667 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1668 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1669 SSH_KEY_BITS_RESERVED) {
1670 options.server_key_bits =
1671 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1672 SSH_KEY_BITS_RESERVED;
1673 debug("Forcing server key to %d bits to make it differ from host key.",
1674 options.server_key_bits);
1681 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1682 (S_ISDIR(st.st_mode) == 0))
1683 fatal("Missing privilege separation directory: %s",
1684 _PATH_PRIVSEP_CHROOT_DIR);
1687 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1688 (st.st_uid != getuid () ||
1689 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1691 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1693 fatal("%s must be owned by root and not group or "
1694 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1697 if (test_flag > 1) {
1698 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1699 parse_server_match_config(&options, test_user,
1700 test_host, test_addr);
1701 dump_config(&options);
1704 /* Configuration looks good, so exit if in test mode. */
1709 * Clear out any supplemental groups we may have inherited. This
1710 * prevents inadvertent creation of files with bad modes (in the
1711 * portable version at least, it's certainly possible for PAM
1712 * to create a file, and we can't control the code in every
1713 * module which might be used).
1715 if (setgroups(0, NULL) < 0)
1716 debug("setgroups() failed: %.200s", strerror(errno));
1719 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1720 for (i = 0; i < rexec_argc; i++) {
1721 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1722 rexec_argv[i] = saved_argv[i];
1724 rexec_argv[rexec_argc] = "-R";
1725 rexec_argv[rexec_argc + 1] = NULL;
1728 /* Ensure that umask disallows at least group and world write */
1729 new_umask = umask(0077) | 0022;
1730 (void) umask(new_umask);
1732 /* Initialize the log (it is reinitialized below in case we forked). */
1733 if (debug_flag && (!inetd_flag || rexeced_flag))
1735 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1738 * If not in debugging mode, and not started from inetd, disconnect
1739 * from the controlling terminal, and fork. The original process
1742 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1745 #endif /* TIOCNOTTY */
1746 if (daemon(0, 0) < 0)
1747 fatal("daemon() failed: %.200s", strerror(errno));
1749 /* Disconnect from the controlling tty. */
1751 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1753 (void) ioctl(fd, TIOCNOTTY, NULL);
1756 #endif /* TIOCNOTTY */
1758 /* Reinitialize the log (because of the fork above). */
1759 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1761 /* Avoid killing the process in high-pressure swapping environments. */
1762 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0)
1763 debug("madvise(): %.200s", strerror(errno));
1765 /* Initialize the random number generator. */
1768 /* Chdir to the root directory so that the current disk can be
1769 unmounted if desired. */
1772 /* ignore SIGPIPE */
1773 signal(SIGPIPE, SIG_IGN);
1775 /* Get a connection, either from inetd or a listening TCP socket */
1777 server_accept_inetd(&sock_in, &sock_out);
1779 platform_pre_listen();
1782 if (options.protocol & SSH_PROTO_1)
1783 generate_ephemeral_server_key();
1785 signal(SIGHUP, sighup_handler);
1786 signal(SIGCHLD, main_sigchld_handler);
1787 signal(SIGTERM, sigterm_handler);
1788 signal(SIGQUIT, sigterm_handler);
1791 * Write out the pid file after the sigterm handler
1792 * is setup and the listen sockets are bound
1795 FILE *f = fopen(options.pid_file, "w");
1798 error("Couldn't create pid file \"%s\": %s",
1799 options.pid_file, strerror(errno));
1801 fprintf(f, "%ld\n", (long) getpid());
1806 /* Accept a connection and return in a forked child */
1807 server_accept_loop(&sock_in, &sock_out,
1808 &newsock, config_s);
1811 /* This is the child processing a new connection. */
1812 setproctitle("%s", "[accepted]");
1815 * Create a new session and process group since the 4.4BSD
1816 * setlogin() affects the entire process group. We don't
1817 * want the child to be able to affect the parent.
1819 #if !defined(SSHD_ACQUIRES_CTTY)
1821 * If setsid is called, on some platforms sshd will later acquire a
1822 * controlling terminal which will result in "could not set
1823 * controlling tty" errors.
1825 if (!debug_flag && !inetd_flag && setsid() < 0)
1826 error("setsid: %.100s", strerror(errno));
1832 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1833 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1834 dup2(newsock, STDIN_FILENO);
1835 dup2(STDIN_FILENO, STDOUT_FILENO);
1836 if (startup_pipe == -1)
1837 close(REEXEC_STARTUP_PIPE_FD);
1839 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1841 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1843 if (startup_pipe != -1)
1844 close(startup_pipe);
1846 execv(rexec_argv[0], rexec_argv);
1848 /* Reexec has failed, fall back and continue */
1849 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1850 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1851 log_init(__progname, options.log_level,
1852 options.log_facility, log_stderr);
1855 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1857 close(REEXEC_CONFIG_PASS_FD);
1858 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1859 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1860 dup2(fd, STDIN_FILENO);
1861 dup2(fd, STDOUT_FILENO);
1862 if (fd > STDERR_FILENO)
1865 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1866 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1869 /* Executed child processes don't need these. */
1870 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1871 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1874 * Disable the key regeneration alarm. We will not regenerate the
1875 * key since we are no longer in a position to give it to anyone. We
1876 * will not restart on SIGHUP since it no longer makes sense.
1879 signal(SIGALRM, SIG_DFL);
1880 signal(SIGHUP, SIG_DFL);
1881 signal(SIGTERM, SIG_DFL);
1882 signal(SIGQUIT, SIG_DFL);
1883 signal(SIGCHLD, SIG_DFL);
1884 signal(SIGINT, SIG_DFL);
1888 * Initialize the resolver. This may not happen automatically
1889 * before privsep chroot().
1891 if ((_res.options & RES_INIT) == 0) {
1892 debug("res_init()");
1897 * Force GSS-API to parse its configuration and load any
1898 * mechanism plugins.
1902 OM_uint32 minor_status;
1903 gss_indicate_mechs(&minor_status, &mechs);
1904 gss_release_oid_set(&minor_status, &mechs);
1910 * Register our connection. This turns encryption off because we do
1913 packet_set_connection(sock_in, sock_out);
1914 packet_set_server();
1916 /* Set SO_KEEPALIVE if requested. */
1917 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1918 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1919 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1921 if ((remote_port = get_remote_port()) < 0) {
1922 debug("get_remote_port failed");
1927 * We use get_canonical_hostname with usedns = 0 instead of
1928 * get_remote_ipaddr here so IP options will be checked.
1930 (void) get_canonical_hostname(0);
1932 * The rest of the code depends on the fact that
1933 * get_remote_ipaddr() caches the remote ip, even if
1934 * the socket goes away.
1936 remote_ip = get_remote_ipaddr();
1938 #ifdef SSH_AUDIT_EVENTS
1939 audit_connection_from(remote_ip, remote_port);
1942 allow_severity = options.log_facility|LOG_INFO;
1943 deny_severity = options.log_facility|LOG_WARNING;
1944 /* Check whether logins are denied from this host. */
1945 if (packet_connection_is_on_socket()) {
1946 struct request_info req;
1948 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1951 if (!hosts_access(&req)) {
1952 debug("Connection refused by tcp wrapper");
1955 fatal("libwrap refuse returns");
1958 #endif /* LIBWRAP */
1960 /* Log the connection. */
1961 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1964 * We don't want to listen forever unless the other side
1965 * successfully authenticates itself. So we set up an alarm which is
1966 * cleared after successful authentication. A limit of zero
1967 * indicates no limit. Note that we don't set the alarm in debugging
1968 * mode; it is just annoying to have the server exit just when you
1969 * are about to discover the bug.
1971 signal(SIGALRM, grace_alarm_handler);
1973 alarm(options.login_grace_time);
1975 sshd_exchange_identification(sock_in, sock_out);
1977 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1978 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1979 generate_ephemeral_server_key();
1981 packet_set_nonblocking();
1983 /* allocate authentication context */
1984 authctxt = xcalloc(1, sizeof(*authctxt));
1986 authctxt->loginmsg = &loginmsg;
1988 /* XXX global for cleanup, access from other modules */
1989 the_authctxt = authctxt;
1991 /* prepare buffer to collect messages to display to user after login */
1992 buffer_init(&loginmsg);
1996 if (privsep_preauth(authctxt) == 1)
1999 /* perform the key exchange */
2000 /* authenticate user and start session */
2003 do_authentication2(authctxt);
2006 do_authentication(authctxt);
2009 * If we use privilege separation, the unprivileged child transfers
2010 * the current keystate and exits
2013 mm_send_keystate(pmonitor);
2019 * Cancel the alarm we set to limit the time taken for
2023 signal(SIGALRM, SIG_DFL);
2024 authctxt->authenticated = 1;
2025 if (startup_pipe != -1) {
2026 close(startup_pipe);
2030 #ifdef SSH_AUDIT_EVENTS
2031 audit_event(SSH_AUTH_SUCCESS);
2035 if (options.gss_authentication) {
2036 temporarily_use_uid(authctxt->pw);
2037 ssh_gssapi_storecreds();
2042 if (options.use_pam) {
2049 * In privilege separation, we fork another child and prepare
2050 * file descriptor passing.
2053 privsep_postauth(authctxt);
2054 /* the monitor process [priv] will not return */
2056 destroy_sensitive_data();
2059 packet_set_timeout(options.client_alive_interval,
2060 options.client_alive_count_max);
2062 /* Start session. */
2063 do_authenticated(authctxt);
2065 /* The connection has been terminated. */
2066 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2067 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2068 verbose("Transferred: sent %llu, received %llu bytes",
2069 (unsigned long long)obytes, (unsigned long long)ibytes);
2071 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2074 if (options.use_pam)
2076 #endif /* USE_PAM */
2078 #ifdef SSH_AUDIT_EVENTS
2079 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2091 * Decrypt session_key_int using our private server key and private host key
2092 * (key with larger modulus first).
2095 ssh1_session_key(BIGNUM *session_key_int)
2099 if (BN_cmp(sensitive_data.server_key->rsa->n,
2100 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2101 /* Server key has bigger modulus. */
2102 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2103 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2104 SSH_KEY_BITS_RESERVED) {
2105 fatal("do_connection: %s: "
2106 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2107 get_remote_ipaddr(),
2108 BN_num_bits(sensitive_data.server_key->rsa->n),
2109 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2110 SSH_KEY_BITS_RESERVED);
2112 if (rsa_private_decrypt(session_key_int, session_key_int,
2113 sensitive_data.server_key->rsa) <= 0)
2115 if (rsa_private_decrypt(session_key_int, session_key_int,
2116 sensitive_data.ssh1_host_key->rsa) <= 0)
2119 /* Host key has bigger modulus (or they are equal). */
2120 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2121 BN_num_bits(sensitive_data.server_key->rsa->n) +
2122 SSH_KEY_BITS_RESERVED) {
2123 fatal("do_connection: %s: "
2124 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2125 get_remote_ipaddr(),
2126 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2127 BN_num_bits(sensitive_data.server_key->rsa->n),
2128 SSH_KEY_BITS_RESERVED);
2130 if (rsa_private_decrypt(session_key_int, session_key_int,
2131 sensitive_data.ssh1_host_key->rsa) < 0)
2133 if (rsa_private_decrypt(session_key_int, session_key_int,
2134 sensitive_data.server_key->rsa) < 0)
2147 BIGNUM *session_key_int;
2148 u_char session_key[SSH_SESSION_KEY_LENGTH];
2150 u_int cipher_type, auth_mask, protocol_flags;
2153 * Generate check bytes that the client must send back in the user
2154 * packet in order for it to be accepted; this is used to defy ip
2155 * spoofing attacks. Note that this only works against somebody
2156 * doing IP spoofing from a remote machine; any machine on the local
2157 * network can still see outgoing packets and catch the random
2158 * cookie. This only affects rhosts authentication, and this is one
2159 * of the reasons why it is inherently insecure.
2161 arc4random_buf(cookie, sizeof(cookie));
2164 * Send our public key. We include in the packet 64 bits of random
2165 * data that must be matched in the reply in order to prevent IP
2168 packet_start(SSH_SMSG_PUBLIC_KEY);
2169 for (i = 0; i < 8; i++)
2170 packet_put_char(cookie[i]);
2172 /* Store our public server RSA key. */
2173 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2174 packet_put_bignum(sensitive_data.server_key->rsa->e);
2175 packet_put_bignum(sensitive_data.server_key->rsa->n);
2177 /* Store our public host RSA key. */
2178 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2179 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2180 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2182 /* Put protocol flags. */
2183 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2185 /* Declare which ciphers we support. */
2186 packet_put_int(cipher_mask_ssh1(0));
2188 /* Declare supported authentication types. */
2190 if (options.rhosts_rsa_authentication)
2191 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2192 if (options.rsa_authentication)
2193 auth_mask |= 1 << SSH_AUTH_RSA;
2194 if (options.challenge_response_authentication == 1)
2195 auth_mask |= 1 << SSH_AUTH_TIS;
2196 if (options.password_authentication)
2197 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2198 packet_put_int(auth_mask);
2200 /* Send the packet and wait for it to be sent. */
2202 packet_write_wait();
2204 debug("Sent %d bit server key and %d bit host key.",
2205 BN_num_bits(sensitive_data.server_key->rsa->n),
2206 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2208 /* Read clients reply (cipher type and session key). */
2209 packet_read_expect(SSH_CMSG_SESSION_KEY);
2211 /* Get cipher type and check whether we accept this. */
2212 cipher_type = packet_get_char();
2214 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2215 packet_disconnect("Warning: client selects unsupported cipher.");
2217 /* Get check bytes from the packet. These must match those we
2218 sent earlier with the public key packet. */
2219 for (i = 0; i < 8; i++)
2220 if (cookie[i] != packet_get_char())
2221 packet_disconnect("IP Spoofing check bytes do not match.");
2223 debug("Encryption type: %.200s", cipher_name(cipher_type));
2225 /* Get the encrypted integer. */
2226 if ((session_key_int = BN_new()) == NULL)
2227 fatal("do_ssh1_kex: BN_new failed");
2228 packet_get_bignum(session_key_int);
2230 protocol_flags = packet_get_int();
2231 packet_set_protocol_flags(protocol_flags);
2234 /* Decrypt session_key_int using host/server keys */
2235 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2238 * Extract session key from the decrypted integer. The key is in the
2239 * least significant 256 bits of the integer; the first byte of the
2240 * key is in the highest bits.
2243 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2244 len = BN_num_bytes(session_key_int);
2245 if (len < 0 || (u_int)len > sizeof(session_key)) {
2246 error("do_ssh1_kex: bad session key len from %s: "
2247 "session_key_int %d > sizeof(session_key) %lu",
2248 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2251 memset(session_key, 0, sizeof(session_key));
2252 BN_bn2bin(session_key_int,
2253 session_key + sizeof(session_key) - len);
2255 derive_ssh1_session_id(
2256 sensitive_data.ssh1_host_key->rsa->n,
2257 sensitive_data.server_key->rsa->n,
2258 cookie, session_id);
2260 * Xor the first 16 bytes of the session key with the
2263 for (i = 0; i < 16; i++)
2264 session_key[i] ^= session_id[i];
2268 int bytes = BN_num_bytes(session_key_int);
2269 u_char *buf = xmalloc(bytes);
2272 logit("do_connection: generating a fake encryption key");
2273 BN_bn2bin(session_key_int, buf);
2275 MD5_Update(&md, buf, bytes);
2276 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2277 MD5_Final(session_key, &md);
2279 MD5_Update(&md, session_key, 16);
2280 MD5_Update(&md, buf, bytes);
2281 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2282 MD5_Final(session_key + 16, &md);
2283 memset(buf, 0, bytes);
2285 for (i = 0; i < 16; i++)
2286 session_id[i] = session_key[i] ^ session_key[i + 16];
2288 /* Destroy the private and public keys. No longer. */
2289 destroy_sensitive_data();
2292 mm_ssh1_session_id(session_id);
2294 /* Destroy the decrypted integer. It is no longer needed. */
2295 BN_clear_free(session_key_int);
2297 /* Set the session key. From this on all communications will be encrypted. */
2298 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2300 /* Destroy our copy of the session key. It is no longer needed. */
2301 memset(session_key, 0, sizeof(session_key));
2303 debug("Received session key; encryption turned on.");
2305 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2306 packet_start(SSH_SMSG_SUCCESS);
2308 packet_write_wait();
2312 * SSH2 key exchange: diffie-hellman-group1-sha1
2319 if (options.ciphers != NULL) {
2320 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2321 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2323 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2324 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2325 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2326 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2328 if (options.macs != NULL) {
2329 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2330 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2332 if (options.compression == COMP_NONE) {
2333 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2334 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2335 } else if (options.compression == COMP_DELAYED) {
2336 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2337 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2339 if (options.kex_algorithms != NULL)
2340 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
2342 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2344 /* start key exchange */
2345 kex = kex_setup(myproposal);
2346 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2347 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2348 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2349 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2350 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2352 kex->client_version_string=client_version_string;
2353 kex->server_version_string=server_version_string;
2354 kex->load_host_public_key=&get_hostkey_public_by_type;
2355 kex->load_host_private_key=&get_hostkey_private_by_type;
2356 kex->host_key_index=&get_hostkey_index;
2360 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2362 session_id2 = kex->session_id;
2363 session_id2_len = kex->session_id_len;
2366 /* send 1st encrypted/maced/compressed message */
2367 packet_start(SSH2_MSG_IGNORE);
2368 packet_put_cstring("markus");
2370 packet_write_wait();
2375 /* server specific fatal cleanup */
2380 do_cleanup(the_authctxt);
2381 #ifdef SSH_AUDIT_EVENTS
2382 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2383 if (!use_privsep || mm_is_monitor())
2384 audit_event(SSH_CONNECTION_ABANDON);