1 /* $OpenBSD: sshd.c,v 1.381 2011/01/11 06:13:10 djm Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This program is the ssh daemon. It listens for connections from clients,
7 * and performs authentication, executes use commands or shell, and forwards
8 * information to/from the application to the user client over an encrypted
9 * connection. This can also handle forwarding of X11, TCP/IP, and
10 * authentication agent connections.
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
18 * SSH2 implementation:
19 * Privilege Separation:
21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22 * Copyright (c) 2002 Niels Provos. All rights reserved.
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
47 #include <sys/types.h>
48 #include <sys/ioctl.h>
49 #include <sys/socket.h>
50 #ifdef HAVE_SYS_STAT_H
51 # include <sys/stat.h>
53 #ifdef HAVE_SYS_TIME_H
54 # include <sys/time.h>
56 #include "openbsd-compat/sys-tree.h"
57 #include "openbsd-compat/sys-queue.h"
75 #include <openssl/dh.h>
76 #include <openssl/bn.h>
77 #include <openssl/md5.h>
78 #include <openssl/rand.h>
79 #include "openbsd-compat/openssl-compat.h"
81 #ifdef HAVE_SECUREWARE
82 #include <sys/security.h>
103 #include "myproposal.h"
104 #include "authfile.h"
105 #include "pathnames.h"
106 #include "atomicio.h"
107 #include "canohost.h"
108 #include "hostfile.h"
112 #include "dispatch.h"
113 #include "channels.h"
115 #include "monitor_mm.h"
120 #include "monitor_wrap.h"
136 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
137 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
138 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
139 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
144 extern char *__progname;
146 /* Server configuration options. */
147 ServerOptions options;
149 /* Name of the server configuration file. */
150 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
153 * Debug mode flag. This can be set on the command line. If debug
154 * mode is enabled, extra debugging output will be sent to the system
155 * log, the daemon will not go to background, and will exit after processing
156 * the first connection.
160 /* Flag indicating that the daemon should only test the configuration and keys. */
163 /* Flag indicating that the daemon is being started from inetd. */
166 /* Flag indicating that sshd should not detach and become a daemon. */
167 int no_daemon_flag = 0;
169 /* debug goes to stderr unless inetd_flag is set */
172 /* Saved arguments to main(). */
177 int rexeced_flag = 0;
183 * The sockets that the server is listening; this is used in the SIGHUP
186 #define MAX_LISTEN_SOCKS 16
187 int listen_socks[MAX_LISTEN_SOCKS];
188 int num_listen_socks = 0;
191 * the client's version string, passed by sshd2 in compat mode. if != NULL,
192 * sshd will skip the version-number exchange
194 char *client_version_string = NULL;
195 char *server_version_string = NULL;
197 /* for rekeying XXX fixme */
201 * Any really sensitive data in the application is contained in this
202 * structure. The idea is that this structure could be locked into memory so
203 * that the pages do not get written into swap. However, there are some
204 * problems. The private key contains BIGNUMs, and we do not (in principle)
205 * have access to the internals of them, and locking just the structure is
206 * not very useful. Currently, memory locking is not implemented.
209 Key *server_key; /* ephemeral server key */
210 Key *ssh1_host_key; /* ssh1 host key */
211 Key **host_keys; /* all private host keys */
212 Key **host_certificates; /* all public host certificates */
215 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
219 * Flag indicating whether the RSA server key needs to be regenerated.
220 * Is set in the SIGALRM handler and cleared when the key is regenerated.
222 static volatile sig_atomic_t key_do_regen = 0;
224 /* This is set to true when a signal is received. */
225 static volatile sig_atomic_t received_sighup = 0;
226 static volatile sig_atomic_t received_sigterm = 0;
228 /* session identifier, used by RSA-auth */
229 u_char session_id[16];
232 u_char *session_id2 = NULL;
233 u_int session_id2_len = 0;
235 /* record remote hostname or ip */
236 u_int utmp_len = MAXHOSTNAMELEN;
238 /* options.max_startup sized array of fd ints */
239 int *startup_pipes = NULL;
240 int startup_pipe; /* in child */
242 /* variables used for privilege separation */
243 int use_privsep = -1;
244 struct monitor *pmonitor = NULL;
246 /* global authentication context */
247 Authctxt *the_authctxt = NULL;
249 /* sshd_config buffer */
252 /* message to be displayed after login */
255 /* Unprivileged user */
256 struct passwd *privsep_pw = NULL;
258 /* Prototypes for various functions defined later in this file. */
259 void destroy_sensitive_data(void);
260 void demote_sensitive_data(void);
262 static void do_ssh1_kex(void);
263 static void do_ssh2_kex(void);
266 * Close all listening sockets
269 close_listen_socks(void)
273 for (i = 0; i < num_listen_socks; i++)
274 close(listen_socks[i]);
275 num_listen_socks = -1;
279 close_startup_pipes(void)
284 for (i = 0; i < options.max_startups; i++)
285 if (startup_pipes[i] != -1)
286 close(startup_pipes[i]);
290 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
291 * the effect is to reread the configuration file (and to regenerate
297 sighup_handler(int sig)
299 int save_errno = errno;
302 signal(SIGHUP, sighup_handler);
307 * Called from the main program after receiving SIGHUP.
308 * Restarts the server.
313 logit("Received SIGHUP; restarting.");
314 close_listen_socks();
315 close_startup_pipes();
316 alarm(0); /* alarm timer persists across exec */
317 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
318 execv(saved_argv[0], saved_argv);
319 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
325 * Generic signal handler for terminating signals in the master daemon.
329 sigterm_handler(int sig)
331 received_sigterm = sig;
335 * SIGCHLD handler. This is called whenever a child dies. This will then
336 * reap any zombies left by exited children.
340 main_sigchld_handler(int sig)
342 int save_errno = errno;
346 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
347 (pid < 0 && errno == EINTR))
350 signal(SIGCHLD, main_sigchld_handler);
355 * Signal handler for the alarm after the login grace period has expired.
359 grace_alarm_handler(int sig)
361 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
362 kill(pmonitor->m_pid, SIGALRM);
364 /* Log error and exit. */
365 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
369 * Signal handler for the key regeneration alarm. Note that this
370 * alarm only occurs in the daemon waiting for connections, and it does not
371 * do anything with the private key or random state before forking.
372 * Thus there should be no concurrency control/asynchronous execution
376 generate_ephemeral_server_key(void)
378 verbose("Generating %s%d bit RSA key.",
379 sensitive_data.server_key ? "new " : "", options.server_key_bits);
380 if (sensitive_data.server_key != NULL)
381 key_free(sensitive_data.server_key);
382 sensitive_data.server_key = key_generate(KEY_RSA1,
383 options.server_key_bits);
384 verbose("RSA key generation complete.");
386 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
392 key_regeneration_alarm(int sig)
394 int save_errno = errno;
396 signal(SIGALRM, SIG_DFL);
402 sshd_exchange_identification(int sock_in, int sock_out)
406 int remote_major, remote_minor;
408 char *s, *newline = "\n";
409 char buf[256]; /* Must not be larger than remote_version. */
410 char remote_version[256]; /* Must be at least as big as buf. */
412 if ((options.protocol & SSH_PROTO_1) &&
413 (options.protocol & SSH_PROTO_2)) {
414 major = PROTOCOL_MAJOR_1;
416 } else if (options.protocol & SSH_PROTO_2) {
417 major = PROTOCOL_MAJOR_2;
418 minor = PROTOCOL_MINOR_2;
421 major = PROTOCOL_MAJOR_1;
422 minor = PROTOCOL_MINOR_1;
424 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
425 SSH_RELEASE, newline);
426 server_version_string = xstrdup(buf);
428 /* Send our protocol version identification. */
429 if (roaming_atomicio(vwrite, sock_out, server_version_string,
430 strlen(server_version_string))
431 != strlen(server_version_string)) {
432 logit("Could not write ident string to %s", get_remote_ipaddr());
436 /* Read other sides version identification. */
437 memset(buf, 0, sizeof(buf));
438 for (i = 0; i < sizeof(buf) - 1; i++) {
439 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
440 logit("Did not receive identification string from %s",
441 get_remote_ipaddr());
444 if (buf[i] == '\r') {
446 /* Kludge for F-Secure Macintosh < 1.0.2 */
448 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
452 if (buf[i] == '\n') {
457 buf[sizeof(buf) - 1] = 0;
458 client_version_string = xstrdup(buf);
461 * Check that the versions match. In future this might accept
462 * several versions and set appropriate flags to handle them.
464 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
465 &remote_major, &remote_minor, remote_version) != 3) {
466 s = "Protocol mismatch.\n";
467 (void) atomicio(vwrite, sock_out, s, strlen(s));
470 logit("Bad protocol version identification '%.100s' from %s",
471 client_version_string, get_remote_ipaddr());
474 debug("Client protocol version %d.%d; client software version %.100s",
475 remote_major, remote_minor, remote_version);
476 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s",
477 get_remote_ipaddr(), get_remote_port(),
478 remote_major, remote_minor, remote_version);
480 compat_datafellows(remote_version);
482 if (datafellows & SSH_BUG_PROBE) {
483 logit("probed from %s with %s. Don't panic.",
484 get_remote_ipaddr(), client_version_string);
488 if (datafellows & SSH_BUG_SCANNER) {
489 logit("scanned from %s with %s. Don't panic.",
490 get_remote_ipaddr(), client_version_string);
495 switch (remote_major) {
497 if (remote_minor == 99) {
498 if (options.protocol & SSH_PROTO_2)
504 if (!(options.protocol & SSH_PROTO_1)) {
508 if (remote_minor < 3) {
509 packet_disconnect("Your ssh version is too old and "
510 "is no longer supported. Please install a newer version.");
511 } else if (remote_minor == 3) {
512 /* note that this disables agent-forwarding */
517 if (options.protocol & SSH_PROTO_2) {
526 chop(server_version_string);
527 debug("Local version string %.200s", server_version_string);
530 s = "Protocol major versions differ.\n";
531 (void) atomicio(vwrite, sock_out, s, strlen(s));
534 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
536 server_version_string, client_version_string);
541 /* Destroy the host and server keys. They will no longer be needed. */
543 destroy_sensitive_data(void)
547 if (sensitive_data.server_key) {
548 key_free(sensitive_data.server_key);
549 sensitive_data.server_key = NULL;
551 for (i = 0; i < options.num_host_key_files; i++) {
552 if (sensitive_data.host_keys[i]) {
553 key_free(sensitive_data.host_keys[i]);
554 sensitive_data.host_keys[i] = NULL;
556 if (sensitive_data.host_certificates[i]) {
557 key_free(sensitive_data.host_certificates[i]);
558 sensitive_data.host_certificates[i] = NULL;
561 sensitive_data.ssh1_host_key = NULL;
562 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
565 /* Demote private to public keys for network child */
567 demote_sensitive_data(void)
572 if (sensitive_data.server_key) {
573 tmp = key_demote(sensitive_data.server_key);
574 key_free(sensitive_data.server_key);
575 sensitive_data.server_key = tmp;
578 for (i = 0; i < options.num_host_key_files; i++) {
579 if (sensitive_data.host_keys[i]) {
580 tmp = key_demote(sensitive_data.host_keys[i]);
581 key_free(sensitive_data.host_keys[i]);
582 sensitive_data.host_keys[i] = tmp;
583 if (tmp->type == KEY_RSA1)
584 sensitive_data.ssh1_host_key = tmp;
586 /* Certs do not need demotion */
589 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
593 privsep_preauth_child(void)
598 /* Enable challenge-response authentication for privilege separation */
599 privsep_challenge_enable();
602 arc4random_buf(rnd, sizeof(rnd));
603 RAND_seed(rnd, sizeof(rnd));
605 /* Demote the private keys to public keys. */
606 demote_sensitive_data();
608 /* Change our root directory */
609 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
610 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
612 if (chdir("/") == -1)
613 fatal("chdir(\"/\"): %s", strerror(errno));
615 /* Drop our privileges */
616 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
617 (u_int)privsep_pw->pw_gid);
619 /* XXX not ready, too heavy after chroot */
620 do_setusercontext(privsep_pw);
622 gidset[0] = privsep_pw->pw_gid;
623 if (setgroups(1, gidset) < 0)
624 fatal("setgroups: %.100s", strerror(errno));
625 permanently_set_uid(privsep_pw);
630 privsep_preauth(Authctxt *authctxt)
635 /* Set up unprivileged child process to deal with network data */
636 pmonitor = monitor_init();
637 /* Store a pointer to the kex for later rekeying */
638 pmonitor->m_pkex = &xxx_kex;
642 fatal("fork of unprivileged child failed");
643 } else if (pid != 0) {
644 debug2("Network child is on pid %ld", (long)pid);
646 close(pmonitor->m_recvfd);
647 pmonitor->m_pid = pid;
648 monitor_child_preauth(authctxt, pmonitor);
649 close(pmonitor->m_sendfd);
652 monitor_sync(pmonitor);
654 /* Wait for the child's exit status */
655 while (waitpid(pid, &status, 0) < 0)
662 close(pmonitor->m_sendfd);
664 /* Demote the child */
665 if (getuid() == 0 || geteuid() == 0)
666 privsep_preauth_child();
667 setproctitle("%s", "[net]");
673 privsep_postauth(Authctxt *authctxt)
677 #ifdef DISABLE_FD_PASSING
680 if (authctxt->pw->pw_uid == 0 || options.use_login) {
682 /* File descriptor passing is broken or root login */
687 /* New socket pair */
688 monitor_reinit(pmonitor);
690 pmonitor->m_pid = fork();
691 if (pmonitor->m_pid == -1)
692 fatal("fork of unprivileged child failed");
693 else if (pmonitor->m_pid != 0) {
694 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
695 close(pmonitor->m_recvfd);
696 buffer_clear(&loginmsg);
697 monitor_child_postauth(pmonitor);
703 close(pmonitor->m_sendfd);
705 /* Demote the private keys to public keys. */
706 demote_sensitive_data();
709 arc4random_buf(rnd, sizeof(rnd));
710 RAND_seed(rnd, sizeof(rnd));
712 /* Drop privileges */
713 do_setusercontext(authctxt->pw);
716 /* It is safe now to apply the key state */
717 monitor_apply_keystate(pmonitor);
720 * Tell the packet layer that authentication was successful, since
721 * this information is not part of the key state.
723 packet_set_authenticated();
727 list_hostkey_types(void)
736 for (i = 0; i < options.num_host_key_files; i++) {
737 key = sensitive_data.host_keys[i];
744 if (buffer_len(&b) > 0)
745 buffer_append(&b, ",", 1);
746 p = key_ssh_name(key);
747 buffer_append(&b, p, strlen(p));
750 /* If the private key has a cert peer, then list that too */
751 key = sensitive_data.host_certificates[i];
755 case KEY_RSA_CERT_V00:
756 case KEY_DSA_CERT_V00:
760 if (buffer_len(&b) > 0)
761 buffer_append(&b, ",", 1);
762 p = key_ssh_name(key);
763 buffer_append(&b, p, strlen(p));
767 buffer_append(&b, "\0", 1);
768 ret = xstrdup(buffer_ptr(&b));
770 debug("list_hostkey_types: %s", ret);
775 get_hostkey_by_type(int type, int need_private)
780 for (i = 0; i < options.num_host_key_files; i++) {
782 case KEY_RSA_CERT_V00:
783 case KEY_DSA_CERT_V00:
787 key = sensitive_data.host_certificates[i];
790 key = sensitive_data.host_keys[i];
793 if (key != NULL && key->type == type)
794 return need_private ?
795 sensitive_data.host_keys[i] : key;
801 get_hostkey_public_by_type(int type)
803 return get_hostkey_by_type(type, 0);
807 get_hostkey_private_by_type(int type)
809 return get_hostkey_by_type(type, 1);
813 get_hostkey_by_index(int ind)
815 if (ind < 0 || ind >= options.num_host_key_files)
817 return (sensitive_data.host_keys[ind]);
821 get_hostkey_index(Key *key)
825 for (i = 0; i < options.num_host_key_files; i++) {
826 if (key_is_cert(key)) {
827 if (key == sensitive_data.host_certificates[i])
830 if (key == sensitive_data.host_keys[i])
838 * returns 1 if connection should be dropped, 0 otherwise.
839 * dropping starts at connection #max_startups_begin with a probability
840 * of (max_startups_rate/100). the probability increases linearly until
841 * all connections are dropped for startups > max_startups
844 drop_connection(int startups)
848 if (startups < options.max_startups_begin)
850 if (startups >= options.max_startups)
852 if (options.max_startups_rate == 100)
855 p = 100 - options.max_startups_rate;
856 p *= startups - options.max_startups_begin;
857 p /= options.max_startups - options.max_startups_begin;
858 p += options.max_startups_rate;
859 r = arc4random_uniform(100);
861 debug("drop_connection: p %d, r %d", p, r);
862 return (r < p) ? 1 : 0;
868 fprintf(stderr, "%s, %s\n",
869 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
871 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
872 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
873 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
879 send_rexec_state(int fd, Buffer *conf)
883 debug3("%s: entering fd = %d config len %d", __func__, fd,
887 * Protocol from reexec master to child:
888 * string configuration
889 * u_int ephemeral_key_follows
890 * bignum e (only if ephemeral_key_follows == 1)
896 * string rngseed (only if OpenSSL is not self-seeded)
899 buffer_put_cstring(&m, buffer_ptr(conf));
901 if (sensitive_data.server_key != NULL &&
902 sensitive_data.server_key->type == KEY_RSA1) {
903 buffer_put_int(&m, 1);
904 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
905 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
906 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
907 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
908 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
909 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
911 buffer_put_int(&m, 0);
913 #ifndef OPENSSL_PRNG_ONLY
914 rexec_send_rng_seed(&m);
917 if (ssh_msg_send(fd, 0, &m) == -1)
918 fatal("%s: ssh_msg_send failed", __func__);
922 debug3("%s: done", __func__);
926 recv_rexec_state(int fd, Buffer *conf)
932 debug3("%s: entering fd = %d", __func__, fd);
936 if (ssh_msg_recv(fd, &m) == -1)
937 fatal("%s: ssh_msg_recv failed", __func__);
938 if (buffer_get_char(&m) != 0)
939 fatal("%s: rexec version mismatch", __func__);
941 cp = buffer_get_string(&m, &len);
943 buffer_append(conf, cp, len + 1);
946 if (buffer_get_int(&m)) {
947 if (sensitive_data.server_key != NULL)
948 key_free(sensitive_data.server_key);
949 sensitive_data.server_key = key_new_private(KEY_RSA1);
950 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
951 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
952 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
953 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
954 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
955 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
956 rsa_generate_additional_parameters(
957 sensitive_data.server_key->rsa);
960 #ifndef OPENSSL_PRNG_ONLY
961 rexec_recv_rng_seed(&m);
966 debug3("%s: done", __func__);
969 /* Accept a connection from inetd */
971 server_accept_inetd(int *sock_in, int *sock_out)
977 close(REEXEC_CONFIG_PASS_FD);
978 *sock_in = *sock_out = dup(STDIN_FILENO);
980 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
981 close(REEXEC_STARTUP_PIPE_FD);
984 *sock_in = dup(STDIN_FILENO);
985 *sock_out = dup(STDOUT_FILENO);
988 * We intentionally do not close the descriptors 0, 1, and 2
989 * as our code for setting the descriptors won't work if
990 * ttyfd happens to be one of those.
992 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
993 dup2(fd, STDIN_FILENO);
994 dup2(fd, STDOUT_FILENO);
995 if (fd > STDOUT_FILENO)
998 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1002 * Listen for TCP connections
1007 int ret, listen_sock, on = 1;
1008 struct addrinfo *ai;
1009 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1011 int socksizelen = sizeof(int);
1013 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1014 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1016 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1017 fatal("Too many listen sockets. "
1018 "Enlarge MAX_LISTEN_SOCKS");
1019 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1020 ntop, sizeof(ntop), strport, sizeof(strport),
1021 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1022 error("getnameinfo failed: %.100s",
1023 ssh_gai_strerror(ret));
1026 /* Create socket for listening. */
1027 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1029 if (listen_sock < 0) {
1030 /* kernel may not support ipv6 */
1031 verbose("socket: %.100s", strerror(errno));
1034 if (set_nonblock(listen_sock) == -1) {
1039 * Set socket options.
1040 * Allow local port reuse in TIME_WAIT.
1042 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1043 &on, sizeof(on)) == -1)
1044 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1046 /* Only communicate in IPv6 over AF_INET6 sockets. */
1047 if (ai->ai_family == AF_INET6)
1048 sock_set_v6only(listen_sock);
1050 debug("Bind to port %s on %s.", strport, ntop);
1052 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF,
1053 &socksize, &socksizelen);
1054 debug("Server TCP RWIN socket size: %d", socksize);
1055 debug("HPN Buffer Size: %d", options.hpn_buffer_size);
1057 /* Bind the socket to the desired port. */
1058 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1059 error("Bind to port %s on %s failed: %.200s.",
1060 strport, ntop, strerror(errno));
1064 listen_socks[num_listen_socks] = listen_sock;
1067 /* Start listening on the port. */
1068 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1069 fatal("listen on [%s]:%s: %.100s",
1070 ntop, strport, strerror(errno));
1071 logit("Server listening on %s port %s.", ntop, strport);
1073 freeaddrinfo(options.listen_addrs);
1075 if (!num_listen_socks)
1076 fatal("Cannot bind any address.");
1080 * The main TCP accept loop. Note that, for the non-debug case, returns
1081 * from this function are in a forked subprocess.
1084 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1087 int i, j, ret, maxfd;
1088 int key_used = 0, startups = 0;
1089 int startup_p[2] = { -1 , -1 };
1090 struct sockaddr_storage from;
1094 /* setup fd set for accept */
1097 for (i = 0; i < num_listen_socks; i++)
1098 if (listen_socks[i] > maxfd)
1099 maxfd = listen_socks[i];
1100 /* pipes connected to unauthenticated childs */
1101 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1102 for (i = 0; i < options.max_startups; i++)
1103 startup_pipes[i] = -1;
1106 * Stay listening for connections until the system crashes or
1107 * the daemon is killed with a signal.
1110 if (received_sighup)
1114 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1117 for (i = 0; i < num_listen_socks; i++)
1118 FD_SET(listen_socks[i], fdset);
1119 for (i = 0; i < options.max_startups; i++)
1120 if (startup_pipes[i] != -1)
1121 FD_SET(startup_pipes[i], fdset);
1123 /* Wait in select until there is a connection. */
1124 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1125 if (ret < 0 && errno != EINTR)
1126 error("select: %.100s", strerror(errno));
1127 if (received_sigterm) {
1128 logit("Received signal %d; terminating.",
1129 (int) received_sigterm);
1130 close_listen_socks();
1131 unlink(options.pid_file);
1134 if (key_used && key_do_regen) {
1135 generate_ephemeral_server_key();
1142 for (i = 0; i < options.max_startups; i++)
1143 if (startup_pipes[i] != -1 &&
1144 FD_ISSET(startup_pipes[i], fdset)) {
1146 * the read end of the pipe is ready
1147 * if the child has closed the pipe
1148 * after successful authentication
1149 * or if the child has died
1151 close(startup_pipes[i]);
1152 startup_pipes[i] = -1;
1155 for (i = 0; i < num_listen_socks; i++) {
1156 if (!FD_ISSET(listen_socks[i], fdset))
1158 fromlen = sizeof(from);
1159 *newsock = accept(listen_socks[i],
1160 (struct sockaddr *)&from, &fromlen);
1162 if (errno != EINTR && errno != EAGAIN &&
1163 errno != EWOULDBLOCK)
1164 error("accept: %.100s", strerror(errno));
1167 if (unset_nonblock(*newsock) == -1) {
1171 if (drop_connection(startups) == 1) {
1172 debug("drop connection #%d", startups);
1176 if (pipe(startup_p) == -1) {
1181 if (rexec_flag && socketpair(AF_UNIX,
1182 SOCK_STREAM, 0, config_s) == -1) {
1183 error("reexec socketpair: %s",
1186 close(startup_p[0]);
1187 close(startup_p[1]);
1191 for (j = 0; j < options.max_startups; j++)
1192 if (startup_pipes[j] == -1) {
1193 startup_pipes[j] = startup_p[0];
1194 if (maxfd < startup_p[0])
1195 maxfd = startup_p[0];
1201 * Got connection. Fork a child to handle it, unless
1202 * we are in debugging mode.
1206 * In debugging mode. Close the listening
1207 * socket, and start processing the
1208 * connection without forking.
1210 debug("Server will not fork when running in debugging mode.");
1211 close_listen_socks();
1212 *sock_in = *newsock;
1213 *sock_out = *newsock;
1214 close(startup_p[0]);
1215 close(startup_p[1]);
1219 send_rexec_state(config_s[0],
1227 * Normal production daemon. Fork, and have
1228 * the child process the connection. The
1229 * parent continues listening.
1231 platform_pre_fork();
1232 if ((pid = fork()) == 0) {
1234 * Child. Close the listening and
1235 * max_startup sockets. Start using
1236 * the accepted socket. Reinitialize
1237 * logging (since our pid has changed).
1238 * We break out of the loop to handle
1241 platform_post_fork_child();
1242 startup_pipe = startup_p[1];
1243 close_startup_pipes();
1244 close_listen_socks();
1245 *sock_in = *newsock;
1246 *sock_out = *newsock;
1247 log_init(__progname,
1249 options.log_facility,
1256 /* Parent. Stay in the loop. */
1257 platform_post_fork_parent(pid);
1259 error("fork: %.100s", strerror(errno));
1261 debug("Forked child %ld.", (long)pid);
1263 close(startup_p[1]);
1266 send_rexec_state(config_s[0], &cfg);
1272 * Mark that the key has been used (it
1273 * was "given" to the child).
1275 if ((options.protocol & SSH_PROTO_1) &&
1277 /* Schedule server key regeneration alarm. */
1278 signal(SIGALRM, key_regeneration_alarm);
1279 alarm(options.key_regeneration_time);
1286 * Ensure that our random state differs
1287 * from that of the child
1292 /* child process check (or debug mode) */
1293 if (num_listen_socks < 0)
1300 * Main program for the daemon.
1303 main(int ac, char **av)
1305 extern char *optarg;
1307 int opt, i, j, on = 1;
1308 int sock_in = -1, sock_out = -1, newsock = -1;
1309 const char *remote_ip;
1310 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1312 char *line, *p, *cp;
1313 int config_s[2] = { -1 , -1 };
1314 u_int64_t ibytes, obytes;
1319 #ifdef HAVE_SECUREWARE
1320 (void)set_auth_parameters(ac, av);
1322 __progname = ssh_get_progname(av[0]);
1325 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1328 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1329 for (i = 0; i < ac; i++)
1330 saved_argv[i] = xstrdup(av[i]);
1331 saved_argv[i] = NULL;
1333 #ifndef HAVE_SETPROCTITLE
1334 /* Prepare for later setproctitle emulation */
1335 compat_init_setproctitle(ac, av);
1339 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1340 debug("setgroups(): %.200s", strerror(errno));
1342 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1345 /* Initialize configuration options to their default values. */
1346 initialize_server_options(&options);
1348 /* Parse command-line arguments. */
1349 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1352 options.address_family = AF_INET;
1355 options.address_family = AF_INET6;
1358 config_file_name = optarg;
1361 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1362 fprintf(stderr, "too many host certificates.\n");
1365 options.host_cert_files[options.num_host_cert_files++] =
1366 derelativise_path(optarg);
1369 if (debug_flag == 0) {
1371 options.log_level = SYSLOG_LEVEL_DEBUG1;
1372 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1373 options.log_level++;
1395 options.log_level = SYSLOG_LEVEL_QUIET;
1398 options.server_key_bits = (int)strtonum(optarg, 256,
1402 options.ports_from_cmdline = 1;
1403 if (options.num_ports >= MAX_PORTS) {
1404 fprintf(stderr, "too many ports.\n");
1407 options.ports[options.num_ports++] = a2port(optarg);
1408 if (options.ports[options.num_ports-1] <= 0) {
1409 fprintf(stderr, "Bad port number.\n");
1414 if ((options.login_grace_time = convtime(optarg)) == -1) {
1415 fprintf(stderr, "Invalid login grace time.\n");
1420 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1421 fprintf(stderr, "Invalid key regeneration interval.\n");
1426 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1427 fprintf(stderr, "too many host keys.\n");
1430 options.host_key_files[options.num_host_key_files++] =
1431 derelativise_path(optarg);
1441 while ((p = strsep(&cp, ",")) && *p != '\0') {
1442 if (strncmp(p, "addr=", 5) == 0)
1443 test_addr = xstrdup(p + 5);
1444 else if (strncmp(p, "host=", 5) == 0)
1445 test_host = xstrdup(p + 5);
1446 else if (strncmp(p, "user=", 5) == 0)
1447 test_user = xstrdup(p + 5);
1449 fprintf(stderr, "Invalid test "
1450 "mode specification %s\n", p);
1456 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1457 if (utmp_len > MAXHOSTNAMELEN) {
1458 fprintf(stderr, "Invalid utmp length.\n");
1463 line = xstrdup(optarg);
1464 if (process_server_config_line(&options, line,
1465 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1475 if (rexeced_flag || inetd_flag)
1477 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1478 fatal("sshd re-exec requires execution with an absolute path");
1480 closefrom(REEXEC_MIN_FREE_FD);
1482 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1484 OpenSSL_add_all_algorithms();
1487 * Force logging to stderr until we have loaded the private host
1488 * key (unless started from inetd)
1490 log_init(__progname,
1491 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1492 SYSLOG_LEVEL_INFO : options.log_level,
1493 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1494 SYSLOG_FACILITY_AUTH : options.log_facility,
1495 log_stderr || !inetd_flag);
1498 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1499 * root's environment
1501 if (getenv("KRB5CCNAME") != NULL)
1502 unsetenv("KRB5CCNAME");
1505 /* Cray can define user privs drop all privs now!
1506 * Not needed on PRIV_SU systems!
1511 sensitive_data.server_key = NULL;
1512 sensitive_data.ssh1_host_key = NULL;
1513 sensitive_data.have_ssh1_key = 0;
1514 sensitive_data.have_ssh2_key = 0;
1517 * If we're doing an extended config test, make sure we have all of
1518 * the parameters we need. If we're not doing an extended test,
1519 * do not silently ignore connection test params.
1521 if (test_flag >= 2 &&
1522 (test_user != NULL || test_host != NULL || test_addr != NULL)
1523 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1524 fatal("user, host and addr are all required when testing "
1526 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1528 fatal("Config test connection parameter (-C) provided without "
1531 /* Fetch our configuration */
1534 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1536 load_server_config(config_file_name, &cfg);
1538 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1539 &cfg, NULL, NULL, NULL);
1543 /* Fill in default values for those options not explicitly set. */
1544 fill_default_server_options(&options);
1546 /* challenge-response is implemented via keyboard interactive */
1547 if (options.challenge_response_authentication)
1548 options.kbd_interactive_authentication = 1;
1550 /* set default channel AF */
1551 channel_set_af(options.address_family);
1553 /* Check that there are no remaining arguments. */
1555 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1559 debug("sshd version %.100s", SSH_RELEASE);
1561 /* Store privilege separation user for later use if required. */
1562 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1563 if (use_privsep || options.kerberos_authentication)
1564 fatal("Privilege separation user %s does not exist",
1567 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1568 privsep_pw = pwcopy(privsep_pw);
1569 xfree(privsep_pw->pw_passwd);
1570 privsep_pw->pw_passwd = xstrdup("*");
1574 /* load private host keys */
1575 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1577 for (i = 0; i < options.num_host_key_files; i++)
1578 sensitive_data.host_keys[i] = NULL;
1580 for (i = 0; i < options.num_host_key_files; i++) {
1581 key = key_load_private(options.host_key_files[i], "", NULL);
1582 if (key && blacklisted_key(key)) {
1584 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
1585 if (options.permit_blacklisted_keys)
1586 error("Host key %s blacklisted (see "
1587 "ssh-vulnkey(1)); continuing anyway", fp);
1589 error("Host key %s blacklisted (see "
1590 "ssh-vulnkey(1))", fp);
1592 if (!options.permit_blacklisted_keys) {
1593 sensitive_data.host_keys[i] = NULL;
1597 sensitive_data.host_keys[i] = key;
1599 error("Could not load host key: %s",
1600 options.host_key_files[i]);
1601 sensitive_data.host_keys[i] = NULL;
1604 switch (key->type) {
1606 sensitive_data.ssh1_host_key = key;
1607 sensitive_data.have_ssh1_key = 1;
1612 sensitive_data.have_ssh2_key = 1;
1615 debug("private host key: #%d type %d %s", i, key->type,
1618 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1619 logit("Disabling protocol version 1. Could not load host key");
1620 options.protocol &= ~SSH_PROTO_1;
1622 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1623 logit("Disabling protocol version 2. Could not load host key");
1624 options.protocol &= ~SSH_PROTO_2;
1626 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1627 logit("sshd: no hostkeys available -- exiting.");
1632 * Load certificates. They are stored in an array at identical
1633 * indices to the public keys that they relate to.
1635 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1637 for (i = 0; i < options.num_host_key_files; i++)
1638 sensitive_data.host_certificates[i] = NULL;
1640 for (i = 0; i < options.num_host_cert_files; i++) {
1641 key = key_load_public(options.host_cert_files[i], NULL);
1643 error("Could not load host certificate: %s",
1644 options.host_cert_files[i]);
1647 if (!key_is_cert(key)) {
1648 error("Certificate file is not a certificate: %s",
1649 options.host_cert_files[i]);
1653 /* Find matching private key */
1654 for (j = 0; j < options.num_host_key_files; j++) {
1655 if (key_equal_public(key,
1656 sensitive_data.host_keys[j])) {
1657 sensitive_data.host_certificates[j] = key;
1661 if (j >= options.num_host_key_files) {
1662 error("No matching private key for certificate: %s",
1663 options.host_cert_files[i]);
1667 sensitive_data.host_certificates[j] = key;
1668 debug("host certificate: #%d type %d %s", j, key->type,
1671 /* Check certain values for sanity. */
1672 if (options.protocol & SSH_PROTO_1) {
1673 if (options.server_key_bits < 512 ||
1674 options.server_key_bits > 32768) {
1675 fprintf(stderr, "Bad server key size.\n");
1679 * Check that server and host key lengths differ sufficiently. This
1680 * is necessary to make double encryption work with rsaref. Oh, I
1681 * hate software patents. I dont know if this can go? Niels
1683 if (options.server_key_bits >
1684 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1685 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1686 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1687 SSH_KEY_BITS_RESERVED) {
1688 options.server_key_bits =
1689 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1690 SSH_KEY_BITS_RESERVED;
1691 debug("Forcing server key to %d bits to make it differ from host key.",
1692 options.server_key_bits);
1699 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1700 (S_ISDIR(st.st_mode) == 0))
1701 fatal("Missing privilege separation directory: %s",
1702 _PATH_PRIVSEP_CHROOT_DIR);
1705 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1706 (st.st_uid != getuid () ||
1707 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1709 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1711 fatal("%s must be owned by root and not group or "
1712 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1715 if (test_flag > 1) {
1716 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1717 parse_server_match_config(&options, test_user,
1718 test_host, test_addr);
1719 dump_config(&options);
1722 /* Configuration looks good, so exit if in test mode. */
1727 * Clear out any supplemental groups we may have inherited. This
1728 * prevents inadvertent creation of files with bad modes (in the
1729 * portable version at least, it's certainly possible for PAM
1730 * to create a file, and we can't control the code in every
1731 * module which might be used).
1733 if (setgroups(0, NULL) < 0)
1734 debug("setgroups() failed: %.200s", strerror(errno));
1737 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1738 for (i = 0; i < rexec_argc; i++) {
1739 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1740 rexec_argv[i] = saved_argv[i];
1742 rexec_argv[rexec_argc] = "-R";
1743 rexec_argv[rexec_argc + 1] = NULL;
1746 /* Ensure that umask disallows at least group and world write */
1747 new_umask = umask(0077) | 0022;
1748 (void) umask(new_umask);
1750 /* Initialize the log (it is reinitialized below in case we forked). */
1751 if (debug_flag && (!inetd_flag || rexeced_flag))
1753 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1756 * If not in debugging mode, and not started from inetd, disconnect
1757 * from the controlling terminal, and fork. The original process
1760 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1763 #endif /* TIOCNOTTY */
1764 if (daemon(0, 0) < 0)
1765 fatal("daemon() failed: %.200s", strerror(errno));
1767 /* Disconnect from the controlling tty. */
1769 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1771 (void) ioctl(fd, TIOCNOTTY, NULL);
1774 #endif /* TIOCNOTTY */
1776 /* Reinitialize the log (because of the fork above). */
1777 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1779 /* Initialize the random number generator. */
1782 /* Chdir to the root directory so that the current disk can be
1783 unmounted if desired. */
1786 /* ignore SIGPIPE */
1787 signal(SIGPIPE, SIG_IGN);
1789 /* Get a connection, either from inetd or a listening TCP socket */
1791 server_accept_inetd(&sock_in, &sock_out);
1793 platform_pre_listen();
1796 if (options.protocol & SSH_PROTO_1)
1797 generate_ephemeral_server_key();
1799 signal(SIGHUP, sighup_handler);
1800 signal(SIGCHLD, main_sigchld_handler);
1801 signal(SIGTERM, sigterm_handler);
1802 signal(SIGQUIT, sigterm_handler);
1805 * Write out the pid file after the sigterm handler
1806 * is setup and the listen sockets are bound
1809 FILE *f = fopen(options.pid_file, "w");
1812 error("Couldn't create pid file \"%s\": %s",
1813 options.pid_file, strerror(errno));
1815 fprintf(f, "%ld\n", (long) getpid());
1820 /* Accept a connection and return in a forked child */
1821 server_accept_loop(&sock_in, &sock_out,
1822 &newsock, config_s);
1825 /* This is the child processing a new connection. */
1826 setproctitle("%s", "[accepted]");
1829 * Initialize the resolver. This may not happen automatically
1830 * before privsep chroot().
1832 if ((_res.options & RES_INIT) == 0) {
1833 debug("res_init()");
1838 * Create a new session and process group since the 4.4BSD
1839 * setlogin() affects the entire process group. We don't
1840 * want the child to be able to affect the parent.
1842 #if !defined(SSHD_ACQUIRES_CTTY)
1844 * If setsid is called, on some platforms sshd will later acquire a
1845 * controlling terminal which will result in "could not set
1846 * controlling tty" errors.
1848 if (!debug_flag && !inetd_flag && setsid() < 0)
1849 error("setsid: %.100s", strerror(errno));
1855 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1856 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1857 dup2(newsock, STDIN_FILENO);
1858 dup2(STDIN_FILENO, STDOUT_FILENO);
1859 if (startup_pipe == -1)
1860 close(REEXEC_STARTUP_PIPE_FD);
1862 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1864 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1866 if (startup_pipe != -1)
1867 close(startup_pipe);
1869 execv(rexec_argv[0], rexec_argv);
1871 /* Reexec has failed, fall back and continue */
1872 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1873 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1874 log_init(__progname, options.log_level,
1875 options.log_facility, log_stderr);
1878 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1880 close(REEXEC_CONFIG_PASS_FD);
1881 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1882 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1883 dup2(fd, STDIN_FILENO);
1884 dup2(fd, STDOUT_FILENO);
1885 if (fd > STDERR_FILENO)
1888 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1889 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1892 /* Executed child processes don't need these. */
1893 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1894 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1897 * Disable the key regeneration alarm. We will not regenerate the
1898 * key since we are no longer in a position to give it to anyone. We
1899 * will not restart on SIGHUP since it no longer makes sense.
1902 signal(SIGALRM, SIG_DFL);
1903 signal(SIGHUP, SIG_DFL);
1904 signal(SIGTERM, SIG_DFL);
1905 signal(SIGQUIT, SIG_DFL);
1906 signal(SIGCHLD, SIG_DFL);
1907 signal(SIGINT, SIG_DFL);
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);
1963 /* set the HPN options for the child */
1964 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1967 * We don't want to listen forever unless the other side
1968 * successfully authenticates itself. So we set up an alarm which is
1969 * cleared after successful authentication. A limit of zero
1970 * indicates no limit. Note that we don't set the alarm in debugging
1971 * mode; it is just annoying to have the server exit just when you
1972 * are about to discover the bug.
1974 signal(SIGALRM, grace_alarm_handler);
1976 alarm(options.login_grace_time);
1978 sshd_exchange_identification(sock_in, sock_out);
1980 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1981 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1982 generate_ephemeral_server_key();
1984 packet_set_nonblocking();
1986 /* allocate authentication context */
1987 authctxt = xcalloc(1, sizeof(*authctxt));
1989 authctxt->loginmsg = &loginmsg;
1991 /* XXX global for cleanup, access from other modules */
1992 the_authctxt = authctxt;
1994 /* prepare buffer to collect messages to display to user after login */
1995 buffer_init(&loginmsg);
1999 if (privsep_preauth(authctxt) == 1)
2002 /* perform the key exchange */
2003 /* authenticate user and start session */
2006 do_authentication2(authctxt);
2009 do_authentication(authctxt);
2012 * If we use privilege separation, the unprivileged child transfers
2013 * the current keystate and exits
2016 mm_send_keystate(pmonitor);
2022 * Cancel the alarm we set to limit the time taken for
2026 signal(SIGALRM, SIG_DFL);
2027 authctxt->authenticated = 1;
2028 if (startup_pipe != -1) {
2029 close(startup_pipe);
2033 #ifdef SSH_AUDIT_EVENTS
2034 audit_event(SSH_AUTH_SUCCESS);
2038 if (options.gss_authentication) {
2039 temporarily_use_uid(authctxt->pw);
2040 ssh_gssapi_storecreds();
2045 if (options.use_pam) {
2052 * In privilege separation, we fork another child and prepare
2053 * file descriptor passing.
2056 privsep_postauth(authctxt);
2057 /* the monitor process [priv] will not return */
2059 destroy_sensitive_data();
2062 packet_set_timeout(options.client_alive_interval,
2063 options.client_alive_count_max);
2065 /* Start session. */
2066 do_authenticated(authctxt);
2068 /* The connection has been terminated. */
2069 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2070 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2071 verbose("Transferred: sent %llu, received %llu bytes",
2072 (unsigned long long)obytes, (unsigned long long)ibytes);
2074 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2077 if (options.use_pam)
2079 #endif /* USE_PAM */
2081 #ifdef SSH_AUDIT_EVENTS
2082 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2094 * Decrypt session_key_int using our private server key and private host key
2095 * (key with larger modulus first).
2098 ssh1_session_key(BIGNUM *session_key_int)
2102 if (BN_cmp(sensitive_data.server_key->rsa->n,
2103 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2104 /* Server key has bigger modulus. */
2105 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2106 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2107 SSH_KEY_BITS_RESERVED) {
2108 fatal("do_connection: %s: "
2109 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2110 get_remote_ipaddr(),
2111 BN_num_bits(sensitive_data.server_key->rsa->n),
2112 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2113 SSH_KEY_BITS_RESERVED);
2115 if (rsa_private_decrypt(session_key_int, session_key_int,
2116 sensitive_data.server_key->rsa) <= 0)
2118 if (rsa_private_decrypt(session_key_int, session_key_int,
2119 sensitive_data.ssh1_host_key->rsa) <= 0)
2122 /* Host key has bigger modulus (or they are equal). */
2123 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2124 BN_num_bits(sensitive_data.server_key->rsa->n) +
2125 SSH_KEY_BITS_RESERVED) {
2126 fatal("do_connection: %s: "
2127 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2128 get_remote_ipaddr(),
2129 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2130 BN_num_bits(sensitive_data.server_key->rsa->n),
2131 SSH_KEY_BITS_RESERVED);
2133 if (rsa_private_decrypt(session_key_int, session_key_int,
2134 sensitive_data.ssh1_host_key->rsa) < 0)
2136 if (rsa_private_decrypt(session_key_int, session_key_int,
2137 sensitive_data.server_key->rsa) < 0)
2150 BIGNUM *session_key_int;
2151 u_char session_key[SSH_SESSION_KEY_LENGTH];
2153 u_int cipher_type, auth_mask, protocol_flags;
2156 * Generate check bytes that the client must send back in the user
2157 * packet in order for it to be accepted; this is used to defy ip
2158 * spoofing attacks. Note that this only works against somebody
2159 * doing IP spoofing from a remote machine; any machine on the local
2160 * network can still see outgoing packets and catch the random
2161 * cookie. This only affects rhosts authentication, and this is one
2162 * of the reasons why it is inherently insecure.
2164 arc4random_buf(cookie, sizeof(cookie));
2167 * Send our public key. We include in the packet 64 bits of random
2168 * data that must be matched in the reply in order to prevent IP
2171 packet_start(SSH_SMSG_PUBLIC_KEY);
2172 for (i = 0; i < 8; i++)
2173 packet_put_char(cookie[i]);
2175 /* Store our public server RSA key. */
2176 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2177 packet_put_bignum(sensitive_data.server_key->rsa->e);
2178 packet_put_bignum(sensitive_data.server_key->rsa->n);
2180 /* Store our public host RSA key. */
2181 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2182 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2183 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2185 /* Put protocol flags. */
2186 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2188 /* Declare which ciphers we support. */
2189 packet_put_int(cipher_mask_ssh1(0));
2191 /* Declare supported authentication types. */
2193 if (options.rhosts_rsa_authentication)
2194 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2195 if (options.rsa_authentication)
2196 auth_mask |= 1 << SSH_AUTH_RSA;
2197 if (options.challenge_response_authentication == 1)
2198 auth_mask |= 1 << SSH_AUTH_TIS;
2199 if (options.password_authentication)
2200 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2201 packet_put_int(auth_mask);
2203 /* Send the packet and wait for it to be sent. */
2205 packet_write_wait();
2207 debug("Sent %d bit server key and %d bit host key.",
2208 BN_num_bits(sensitive_data.server_key->rsa->n),
2209 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2211 /* Read clients reply (cipher type and session key). */
2212 packet_read_expect(SSH_CMSG_SESSION_KEY);
2214 /* Get cipher type and check whether we accept this. */
2215 cipher_type = packet_get_char();
2217 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2218 packet_disconnect("Warning: client selects unsupported cipher.");
2220 /* Get check bytes from the packet. These must match those we
2221 sent earlier with the public key packet. */
2222 for (i = 0; i < 8; i++)
2223 if (cookie[i] != packet_get_char())
2224 packet_disconnect("IP Spoofing check bytes do not match.");
2226 debug("Encryption type: %.200s", cipher_name(cipher_type));
2228 /* Get the encrypted integer. */
2229 if ((session_key_int = BN_new()) == NULL)
2230 fatal("do_ssh1_kex: BN_new failed");
2231 packet_get_bignum(session_key_int);
2233 protocol_flags = packet_get_int();
2234 packet_set_protocol_flags(protocol_flags);
2237 /* Decrypt session_key_int using host/server keys */
2238 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2241 * Extract session key from the decrypted integer. The key is in the
2242 * least significant 256 bits of the integer; the first byte of the
2243 * key is in the highest bits.
2246 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2247 len = BN_num_bytes(session_key_int);
2248 if (len < 0 || (u_int)len > sizeof(session_key)) {
2249 error("do_ssh1_kex: bad session key len from %s: "
2250 "session_key_int %d > sizeof(session_key) %lu",
2251 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2254 memset(session_key, 0, sizeof(session_key));
2255 BN_bn2bin(session_key_int,
2256 session_key + sizeof(session_key) - len);
2258 derive_ssh1_session_id(
2259 sensitive_data.ssh1_host_key->rsa->n,
2260 sensitive_data.server_key->rsa->n,
2261 cookie, session_id);
2263 * Xor the first 16 bytes of the session key with the
2266 for (i = 0; i < 16; i++)
2267 session_key[i] ^= session_id[i];
2271 int bytes = BN_num_bytes(session_key_int);
2272 u_char *buf = xmalloc(bytes);
2275 logit("do_connection: generating a fake encryption key");
2276 BN_bn2bin(session_key_int, buf);
2278 MD5_Update(&md, buf, bytes);
2279 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2280 MD5_Final(session_key, &md);
2282 MD5_Update(&md, session_key, 16);
2283 MD5_Update(&md, buf, bytes);
2284 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2285 MD5_Final(session_key + 16, &md);
2286 memset(buf, 0, bytes);
2288 for (i = 0; i < 16; i++)
2289 session_id[i] = session_key[i] ^ session_key[i + 16];
2291 /* Destroy the private and public keys. No longer. */
2292 destroy_sensitive_data();
2295 mm_ssh1_session_id(session_id);
2297 /* Destroy the decrypted integer. It is no longer needed. */
2298 BN_clear_free(session_key_int);
2300 /* Set the session key. From this on all communications will be encrypted. */
2301 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2303 /* Destroy our copy of the session key. It is no longer needed. */
2304 memset(session_key, 0, sizeof(session_key));
2306 debug("Received session key; encryption turned on.");
2308 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2309 packet_start(SSH_SMSG_SUCCESS);
2311 packet_write_wait();
2315 * SSH2 key exchange: diffie-hellman-group1-sha1
2323 debug ("MYFLAG IS %d", myflag);
2324 if (options.ciphers != NULL) {
2325 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2326 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2327 } else if (options.none_enabled == 1) {
2328 debug ("WARNING: None cipher enabled");
2329 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2330 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE;
2332 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2333 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2334 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2335 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2337 if (options.macs != NULL) {
2338 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2339 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2341 if (options.compression == COMP_NONE) {
2342 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2343 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2344 } else if (options.compression == COMP_DELAYED) {
2345 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2346 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2348 if (options.kex_algorithms != NULL)
2349 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
2351 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2353 /* start key exchange */
2354 kex = kex_setup(myproposal);
2355 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2356 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2357 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2358 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2359 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2361 kex->client_version_string=client_version_string;
2362 kex->server_version_string=server_version_string;
2363 kex->load_host_public_key=&get_hostkey_public_by_type;
2364 kex->load_host_private_key=&get_hostkey_private_by_type;
2365 kex->host_key_index=&get_hostkey_index;
2369 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2371 session_id2 = kex->session_id;
2372 session_id2_len = kex->session_id_len;
2375 /* send 1st encrypted/maced/compressed message */
2376 packet_start(SSH2_MSG_IGNORE);
2377 packet_put_cstring("markus");
2379 packet_write_wait();
2384 /* server specific fatal cleanup */
2389 do_cleanup(the_authctxt);
2390 #ifdef SSH_AUDIT_EVENTS
2391 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2392 if (!use_privsep || mm_is_monitor())
2393 audit_event(SSH_CONNECTION_ABANDON);