1 /* $OpenBSD: sshd.c,v 1.381 2011/01/11 06:13:10 djm Exp $ */
4 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
7 * This program is the ssh daemon. It listens for connections from clients,
8 * and performs authentication, executes use commands or shell, and forwards
9 * information to/from the application to the user client over an encrypted
10 * connection. This can also handle forwarding of X11, TCP/IP, and
11 * authentication agent connections.
13 * As far as I am concerned, the code I have written for this software
14 * can be used freely for any purpose. Any derived versions of this
15 * software must be clearly marked as such, and if the derived work is
16 * incompatible with the protocol description in the RFC file, it must be
17 * called by a name other than "ssh" or "Secure Shell".
19 * SSH2 implementation:
20 * Privilege Separation:
22 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
23 * Copyright (c) 2002 Niels Provos. All rights reserved.
25 * Redistribution and use in source and binary forms, with or without
26 * modification, are permitted provided that the following conditions
28 * 1. Redistributions of source code must retain the above copyright
29 * notice, this list of conditions and the following disclaimer.
30 * 2. Redistributions in binary form must reproduce the above copyright
31 * notice, this list of conditions and the following disclaimer in the
32 * documentation and/or other materials provided with the distribution.
34 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
35 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
36 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
37 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
38 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
39 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
40 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
41 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
42 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
43 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
49 #include <sys/types.h>
50 #include <sys/ioctl.h>
52 #include <sys/socket.h>
53 #ifdef HAVE_SYS_STAT_H
54 # include <sys/stat.h>
56 #ifdef HAVE_SYS_TIME_H
57 # include <sys/time.h>
59 #include "openbsd-compat/sys-tree.h"
60 #include "openbsd-compat/sys-queue.h"
78 #include <openssl/dh.h>
79 #include <openssl/bn.h>
80 #include <openssl/md5.h>
81 #include <openssl/rand.h>
82 #include "openbsd-compat/openssl-compat.h"
84 #ifdef HAVE_SECUREWARE
85 #include <sys/security.h>
91 #if defined(GSSAPI) && defined(HAVE_GSSAPI_H)
93 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H)
94 #include <gssapi/gssapi.h>
107 #include "servconf.h"
114 #include "myproposal.h"
115 #include "authfile.h"
116 #include "pathnames.h"
117 #include "atomicio.h"
118 #include "canohost.h"
119 #include "hostfile.h"
123 #include "dispatch.h"
124 #include "channels.h"
126 #include "monitor_mm.h"
131 #include "monitor_wrap.h"
147 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
148 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
149 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
150 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
152 extern char *__progname;
154 /* Server configuration options. */
155 ServerOptions options;
157 /* Name of the server configuration file. */
158 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
161 * Debug mode flag. This can be set on the command line. If debug
162 * mode is enabled, extra debugging output will be sent to the system
163 * log, the daemon will not go to background, and will exit after processing
164 * the first connection.
168 /* Flag indicating that the daemon should only test the configuration and keys. */
171 /* Flag indicating that the daemon is being started from inetd. */
174 /* Flag indicating that sshd should not detach and become a daemon. */
175 int no_daemon_flag = 0;
177 /* debug goes to stderr unless inetd_flag is set */
180 /* Saved arguments to main(). */
185 int rexeced_flag = 0;
191 * The sockets that the server is listening; this is used in the SIGHUP
194 #define MAX_LISTEN_SOCKS 16
195 int listen_socks[MAX_LISTEN_SOCKS];
196 int num_listen_socks = 0;
199 * the client's version string, passed by sshd2 in compat mode. if != NULL,
200 * sshd will skip the version-number exchange
202 char *client_version_string = NULL;
203 char *server_version_string = NULL;
205 /* for rekeying XXX fixme */
209 * Any really sensitive data in the application is contained in this
210 * structure. The idea is that this structure could be locked into memory so
211 * that the pages do not get written into swap. However, there are some
212 * problems. The private key contains BIGNUMs, and we do not (in principle)
213 * have access to the internals of them, and locking just the structure is
214 * not very useful. Currently, memory locking is not implemented.
217 Key *server_key; /* ephemeral server key */
218 Key *ssh1_host_key; /* ssh1 host key */
219 Key **host_keys; /* all private host keys */
220 Key **host_certificates; /* all public host certificates */
223 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
227 * Flag indicating whether the RSA server key needs to be regenerated.
228 * Is set in the SIGALRM handler and cleared when the key is regenerated.
230 static volatile sig_atomic_t key_do_regen = 0;
232 /* This is set to true when a signal is received. */
233 static volatile sig_atomic_t received_sighup = 0;
234 static volatile sig_atomic_t received_sigterm = 0;
236 /* session identifier, used by RSA-auth */
237 u_char session_id[16];
240 u_char *session_id2 = NULL;
241 u_int session_id2_len = 0;
243 /* record remote hostname or ip */
244 u_int utmp_len = MAXHOSTNAMELEN;
246 /* options.max_startup sized array of fd ints */
247 int *startup_pipes = NULL;
248 int startup_pipe; /* in child */
250 /* variables used for privilege separation */
251 int use_privsep = -1;
252 struct monitor *pmonitor = NULL;
254 /* global authentication context */
255 Authctxt *the_authctxt = NULL;
257 /* sshd_config buffer */
260 /* message to be displayed after login */
263 /* Unprivileged user */
264 struct passwd *privsep_pw = NULL;
266 /* Prototypes for various functions defined later in this file. */
267 void destroy_sensitive_data(void);
268 void demote_sensitive_data(void);
270 static void do_ssh1_kex(void);
271 static void do_ssh2_kex(void);
274 * Close all listening sockets
277 close_listen_socks(void)
281 for (i = 0; i < num_listen_socks; i++)
282 close(listen_socks[i]);
283 num_listen_socks = -1;
287 close_startup_pipes(void)
292 for (i = 0; i < options.max_startups; i++)
293 if (startup_pipes[i] != -1)
294 close(startup_pipes[i]);
298 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
299 * the effect is to reread the configuration file (and to regenerate
305 sighup_handler(int sig)
307 int save_errno = errno;
310 signal(SIGHUP, sighup_handler);
315 * Called from the main program after receiving SIGHUP.
316 * Restarts the server.
321 logit("Received SIGHUP; restarting.");
322 close_listen_socks();
323 close_startup_pipes();
324 alarm(0); /* alarm timer persists across exec */
325 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
326 execv(saved_argv[0], saved_argv);
327 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
333 * Generic signal handler for terminating signals in the master daemon.
337 sigterm_handler(int sig)
339 received_sigterm = sig;
343 * SIGCHLD handler. This is called whenever a child dies. This will then
344 * reap any zombies left by exited children.
348 main_sigchld_handler(int sig)
350 int save_errno = errno;
354 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
355 (pid < 0 && errno == EINTR))
358 signal(SIGCHLD, main_sigchld_handler);
363 * Signal handler for the alarm after the login grace period has expired.
367 grace_alarm_handler(int sig)
369 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
370 kill(pmonitor->m_pid, SIGALRM);
372 /* Log error and exit. */
373 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
377 * Signal handler for the key regeneration alarm. Note that this
378 * alarm only occurs in the daemon waiting for connections, and it does not
379 * do anything with the private key or random state before forking.
380 * Thus there should be no concurrency control/asynchronous execution
384 generate_ephemeral_server_key(void)
386 verbose("Generating %s%d bit RSA key.",
387 sensitive_data.server_key ? "new " : "", options.server_key_bits);
388 if (sensitive_data.server_key != NULL)
389 key_free(sensitive_data.server_key);
390 sensitive_data.server_key = key_generate(KEY_RSA1,
391 options.server_key_bits);
392 verbose("RSA key generation complete.");
394 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
400 key_regeneration_alarm(int sig)
402 int save_errno = errno;
404 signal(SIGALRM, SIG_DFL);
410 sshd_exchange_identification(int sock_in, int sock_out)
414 int remote_major, remote_minor;
416 char *s, *newline = "\n";
417 char buf[256]; /* Must not be larger than remote_version. */
418 char remote_version[256]; /* Must be at least as big as buf. */
420 if ((options.protocol & SSH_PROTO_1) &&
421 (options.protocol & SSH_PROTO_2)) {
422 major = PROTOCOL_MAJOR_1;
424 } else if (options.protocol & SSH_PROTO_2) {
425 major = PROTOCOL_MAJOR_2;
426 minor = PROTOCOL_MINOR_2;
429 major = PROTOCOL_MAJOR_1;
430 minor = PROTOCOL_MINOR_1;
432 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
433 SSH_RELEASE, newline);
434 server_version_string = xstrdup(buf);
436 /* Send our protocol version identification. */
437 if (roaming_atomicio(vwrite, sock_out, server_version_string,
438 strlen(server_version_string))
439 != strlen(server_version_string)) {
440 logit("Could not write ident string to %s", get_remote_ipaddr());
444 /* Read other sides version identification. */
445 memset(buf, 0, sizeof(buf));
446 for (i = 0; i < sizeof(buf) - 1; i++) {
447 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
448 logit("Did not receive identification string from %s",
449 get_remote_ipaddr());
452 if (buf[i] == '\r') {
454 /* Kludge for F-Secure Macintosh < 1.0.2 */
456 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
460 if (buf[i] == '\n') {
465 buf[sizeof(buf) - 1] = 0;
466 client_version_string = xstrdup(buf);
469 * Check that the versions match. In future this might accept
470 * several versions and set appropriate flags to handle them.
472 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
473 &remote_major, &remote_minor, remote_version) != 3) {
474 s = "Protocol mismatch.\n";
475 (void) atomicio(vwrite, sock_out, s, strlen(s));
478 logit("Bad protocol version identification '%.100s' from %s",
479 client_version_string, get_remote_ipaddr());
482 debug("Client protocol version %d.%d; client software version %.100s",
483 remote_major, remote_minor, remote_version);
485 compat_datafellows(remote_version);
487 if (datafellows & SSH_BUG_PROBE) {
488 logit("probed from %s with %s. Don't panic.",
489 get_remote_ipaddr(), client_version_string);
493 if (datafellows & SSH_BUG_SCANNER) {
494 logit("scanned from %s with %s. Don't panic.",
495 get_remote_ipaddr(), client_version_string);
500 switch (remote_major) {
502 if (remote_minor == 99) {
503 if (options.protocol & SSH_PROTO_2)
509 if (!(options.protocol & SSH_PROTO_1)) {
513 if (remote_minor < 3) {
514 packet_disconnect("Your ssh version is too old and "
515 "is no longer supported. Please install a newer version.");
516 } else if (remote_minor == 3) {
517 /* note that this disables agent-forwarding */
522 if (options.protocol & SSH_PROTO_2) {
531 chop(server_version_string);
532 debug("Local version string %.200s", server_version_string);
535 s = "Protocol major versions differ.\n";
536 (void) atomicio(vwrite, sock_out, s, strlen(s));
539 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
541 server_version_string, client_version_string);
546 /* Destroy the host and server keys. They will no longer be needed. */
548 destroy_sensitive_data(void)
552 if (sensitive_data.server_key) {
553 key_free(sensitive_data.server_key);
554 sensitive_data.server_key = NULL;
556 for (i = 0; i < options.num_host_key_files; i++) {
557 if (sensitive_data.host_keys[i]) {
558 key_free(sensitive_data.host_keys[i]);
559 sensitive_data.host_keys[i] = NULL;
561 if (sensitive_data.host_certificates[i]) {
562 key_free(sensitive_data.host_certificates[i]);
563 sensitive_data.host_certificates[i] = NULL;
566 sensitive_data.ssh1_host_key = NULL;
567 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
570 /* Demote private to public keys for network child */
572 demote_sensitive_data(void)
577 if (sensitive_data.server_key) {
578 tmp = key_demote(sensitive_data.server_key);
579 key_free(sensitive_data.server_key);
580 sensitive_data.server_key = tmp;
583 for (i = 0; i < options.num_host_key_files; i++) {
584 if (sensitive_data.host_keys[i]) {
585 tmp = key_demote(sensitive_data.host_keys[i]);
586 key_free(sensitive_data.host_keys[i]);
587 sensitive_data.host_keys[i] = tmp;
588 if (tmp->type == KEY_RSA1)
589 sensitive_data.ssh1_host_key = tmp;
591 /* Certs do not need demotion */
594 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
598 privsep_preauth_child(void)
603 /* Enable challenge-response authentication for privilege separation */
604 privsep_challenge_enable();
607 arc4random_buf(rnd, sizeof(rnd));
608 RAND_seed(rnd, sizeof(rnd));
610 /* Demote the private keys to public keys. */
611 demote_sensitive_data();
613 /* Change our root directory */
614 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
615 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
617 if (chdir("/") == -1)
618 fatal("chdir(\"/\"): %s", strerror(errno));
620 /* Drop our privileges */
621 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
622 (u_int)privsep_pw->pw_gid);
624 /* XXX not ready, too heavy after chroot */
625 do_setusercontext(privsep_pw);
627 gidset[0] = privsep_pw->pw_gid;
628 if (setgroups(1, gidset) < 0)
629 fatal("setgroups: %.100s", strerror(errno));
630 permanently_set_uid(privsep_pw);
635 privsep_preauth(Authctxt *authctxt)
640 /* Set up unprivileged child process to deal with network data */
641 pmonitor = monitor_init();
642 /* Store a pointer to the kex for later rekeying */
643 pmonitor->m_pkex = &xxx_kex;
647 fatal("fork of unprivileged child failed");
648 } else if (pid != 0) {
649 debug2("Network child is on pid %ld", (long)pid);
651 close(pmonitor->m_recvfd);
652 pmonitor->m_pid = pid;
653 monitor_child_preauth(authctxt, pmonitor);
654 close(pmonitor->m_sendfd);
657 monitor_sync(pmonitor);
659 /* Wait for the child's exit status */
660 while (waitpid(pid, &status, 0) < 0)
667 close(pmonitor->m_sendfd);
669 /* Demote the child */
670 if (getuid() == 0 || geteuid() == 0)
671 privsep_preauth_child();
672 setproctitle("%s", "[net]");
678 privsep_postauth(Authctxt *authctxt)
682 #ifdef DISABLE_FD_PASSING
685 if (authctxt->pw->pw_uid == 0 || options.use_login) {
687 /* File descriptor passing is broken or root login */
692 /* New socket pair */
693 monitor_reinit(pmonitor);
695 pmonitor->m_pid = fork();
696 if (pmonitor->m_pid == -1)
697 fatal("fork of unprivileged child failed");
698 else if (pmonitor->m_pid != 0) {
699 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
700 close(pmonitor->m_recvfd);
701 buffer_clear(&loginmsg);
702 monitor_child_postauth(pmonitor);
708 close(pmonitor->m_sendfd);
710 /* Demote the private keys to public keys. */
711 demote_sensitive_data();
714 arc4random_buf(rnd, sizeof(rnd));
715 RAND_seed(rnd, sizeof(rnd));
717 /* Drop privileges */
718 do_setusercontext(authctxt->pw);
721 /* It is safe now to apply the key state */
722 monitor_apply_keystate(pmonitor);
725 * Tell the packet layer that authentication was successful, since
726 * this information is not part of the key state.
728 packet_set_authenticated();
732 list_hostkey_types(void)
741 for (i = 0; i < options.num_host_key_files; i++) {
742 key = sensitive_data.host_keys[i];
749 if (buffer_len(&b) > 0)
750 buffer_append(&b, ",", 1);
751 p = key_ssh_name(key);
752 buffer_append(&b, p, strlen(p));
755 /* If the private key has a cert peer, then list that too */
756 key = sensitive_data.host_certificates[i];
760 case KEY_RSA_CERT_V00:
761 case KEY_DSA_CERT_V00:
765 if (buffer_len(&b) > 0)
766 buffer_append(&b, ",", 1);
767 p = key_ssh_name(key);
768 buffer_append(&b, p, strlen(p));
772 buffer_append(&b, "\0", 1);
773 ret = xstrdup(buffer_ptr(&b));
775 debug("list_hostkey_types: %s", ret);
780 get_hostkey_by_type(int type, int need_private)
785 for (i = 0; i < options.num_host_key_files; i++) {
787 case KEY_RSA_CERT_V00:
788 case KEY_DSA_CERT_V00:
792 key = sensitive_data.host_certificates[i];
795 key = sensitive_data.host_keys[i];
798 if (key != NULL && key->type == type)
799 return need_private ?
800 sensitive_data.host_keys[i] : key;
806 get_hostkey_public_by_type(int type)
808 return get_hostkey_by_type(type, 0);
812 get_hostkey_private_by_type(int type)
814 return get_hostkey_by_type(type, 1);
818 get_hostkey_by_index(int ind)
820 if (ind < 0 || ind >= options.num_host_key_files)
822 return (sensitive_data.host_keys[ind]);
826 get_hostkey_index(Key *key)
830 for (i = 0; i < options.num_host_key_files; i++) {
831 if (key_is_cert(key)) {
832 if (key == sensitive_data.host_certificates[i])
835 if (key == sensitive_data.host_keys[i])
843 * returns 1 if connection should be dropped, 0 otherwise.
844 * dropping starts at connection #max_startups_begin with a probability
845 * of (max_startups_rate/100). the probability increases linearly until
846 * all connections are dropped for startups > max_startups
849 drop_connection(int startups)
853 if (startups < options.max_startups_begin)
855 if (startups >= options.max_startups)
857 if (options.max_startups_rate == 100)
860 p = 100 - options.max_startups_rate;
861 p *= startups - options.max_startups_begin;
862 p /= options.max_startups - options.max_startups_begin;
863 p += options.max_startups_rate;
864 r = arc4random_uniform(100);
866 debug("drop_connection: p %d, r %d", p, r);
867 return (r < p) ? 1 : 0;
873 fprintf(stderr, "%s, %s\n",
874 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
876 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
877 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
878 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
884 send_rexec_state(int fd, Buffer *conf)
888 debug3("%s: entering fd = %d config len %d", __func__, fd,
892 * Protocol from reexec master to child:
893 * string configuration
894 * u_int ephemeral_key_follows
895 * bignum e (only if ephemeral_key_follows == 1)
901 * string rngseed (only if OpenSSL is not self-seeded)
904 buffer_put_cstring(&m, buffer_ptr(conf));
906 if (sensitive_data.server_key != NULL &&
907 sensitive_data.server_key->type == KEY_RSA1) {
908 buffer_put_int(&m, 1);
909 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
910 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
911 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
912 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
913 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
914 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
916 buffer_put_int(&m, 0);
918 #ifndef OPENSSL_PRNG_ONLY
919 rexec_send_rng_seed(&m);
922 if (ssh_msg_send(fd, 0, &m) == -1)
923 fatal("%s: ssh_msg_send failed", __func__);
927 debug3("%s: done", __func__);
931 recv_rexec_state(int fd, Buffer *conf)
937 debug3("%s: entering fd = %d", __func__, fd);
941 if (ssh_msg_recv(fd, &m) == -1)
942 fatal("%s: ssh_msg_recv failed", __func__);
943 if (buffer_get_char(&m) != 0)
944 fatal("%s: rexec version mismatch", __func__);
946 cp = buffer_get_string(&m, &len);
948 buffer_append(conf, cp, len + 1);
951 if (buffer_get_int(&m)) {
952 if (sensitive_data.server_key != NULL)
953 key_free(sensitive_data.server_key);
954 sensitive_data.server_key = key_new_private(KEY_RSA1);
955 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
956 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
957 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
958 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
959 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
960 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
961 rsa_generate_additional_parameters(
962 sensitive_data.server_key->rsa);
965 #ifndef OPENSSL_PRNG_ONLY
966 rexec_recv_rng_seed(&m);
971 debug3("%s: done", __func__);
974 /* Accept a connection from inetd */
976 server_accept_inetd(int *sock_in, int *sock_out)
982 close(REEXEC_CONFIG_PASS_FD);
983 *sock_in = *sock_out = dup(STDIN_FILENO);
985 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
986 close(REEXEC_STARTUP_PIPE_FD);
989 *sock_in = dup(STDIN_FILENO);
990 *sock_out = dup(STDOUT_FILENO);
993 * We intentionally do not close the descriptors 0, 1, and 2
994 * as our code for setting the descriptors won't work if
995 * ttyfd happens to be one of those.
997 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
998 dup2(fd, STDIN_FILENO);
999 dup2(fd, STDOUT_FILENO);
1000 if (fd > STDOUT_FILENO)
1003 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1007 * Listen for TCP connections
1012 int ret, listen_sock, on = 1;
1013 struct addrinfo *ai;
1014 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1018 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1019 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1021 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1022 fatal("Too many listen sockets. "
1023 "Enlarge MAX_LISTEN_SOCKS");
1024 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1025 ntop, sizeof(ntop), strport, sizeof(strport),
1026 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1027 error("getnameinfo failed: %.100s",
1028 ssh_gai_strerror(ret));
1031 /* Create socket for listening. */
1032 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1034 if (listen_sock < 0) {
1035 /* kernel may not support ipv6 */
1036 verbose("socket: %.100s", strerror(errno));
1039 if (set_nonblock(listen_sock) == -1) {
1044 * Set socket options.
1045 * Allow local port reuse in TIME_WAIT.
1047 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1048 &on, sizeof(on)) == -1)
1049 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1051 /* Only communicate in IPv6 over AF_INET6 sockets. */
1052 if (ai->ai_family == AF_INET6)
1053 sock_set_v6only(listen_sock);
1055 debug("Bind to port %s on %s.", strport, ntop);
1057 len = sizeof(socksize);
1058 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len);
1059 debug("Server TCP RWIN socket size: %d", socksize);
1060 debug("HPN Buffer Size: %d", options.hpn_buffer_size);
1062 /* Bind the socket to the desired port. */
1063 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1064 error("Bind to port %s on %s failed: %.200s.",
1065 strport, ntop, strerror(errno));
1069 listen_socks[num_listen_socks] = listen_sock;
1072 /* Start listening on the port. */
1073 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1074 fatal("listen on [%s]:%s: %.100s",
1075 ntop, strport, strerror(errno));
1076 logit("Server listening on %s port %s.", ntop, strport);
1078 freeaddrinfo(options.listen_addrs);
1080 if (!num_listen_socks)
1081 fatal("Cannot bind any address.");
1085 * The main TCP accept loop. Note that, for the non-debug case, returns
1086 * from this function are in a forked subprocess.
1089 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1092 int i, j, ret, maxfd;
1093 int key_used = 0, startups = 0;
1094 int startup_p[2] = { -1 , -1 };
1095 struct sockaddr_storage from;
1099 /* setup fd set for accept */
1102 for (i = 0; i < num_listen_socks; i++)
1103 if (listen_socks[i] > maxfd)
1104 maxfd = listen_socks[i];
1105 /* pipes connected to unauthenticated childs */
1106 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1107 for (i = 0; i < options.max_startups; i++)
1108 startup_pipes[i] = -1;
1111 * Stay listening for connections until the system crashes or
1112 * the daemon is killed with a signal.
1115 if (received_sighup)
1119 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1122 for (i = 0; i < num_listen_socks; i++)
1123 FD_SET(listen_socks[i], fdset);
1124 for (i = 0; i < options.max_startups; i++)
1125 if (startup_pipes[i] != -1)
1126 FD_SET(startup_pipes[i], fdset);
1128 /* Wait in select until there is a connection. */
1129 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1130 if (ret < 0 && errno != EINTR)
1131 error("select: %.100s", strerror(errno));
1132 if (received_sigterm) {
1133 logit("Received signal %d; terminating.",
1134 (int) received_sigterm);
1135 close_listen_socks();
1136 unlink(options.pid_file);
1139 if (key_used && key_do_regen) {
1140 generate_ephemeral_server_key();
1147 for (i = 0; i < options.max_startups; i++)
1148 if (startup_pipes[i] != -1 &&
1149 FD_ISSET(startup_pipes[i], fdset)) {
1151 * the read end of the pipe is ready
1152 * if the child has closed the pipe
1153 * after successful authentication
1154 * or if the child has died
1156 close(startup_pipes[i]);
1157 startup_pipes[i] = -1;
1160 for (i = 0; i < num_listen_socks; i++) {
1161 if (!FD_ISSET(listen_socks[i], fdset))
1163 fromlen = sizeof(from);
1164 *newsock = accept(listen_socks[i],
1165 (struct sockaddr *)&from, &fromlen);
1167 if (errno != EINTR && errno != EAGAIN &&
1168 errno != EWOULDBLOCK)
1169 error("accept: %.100s", strerror(errno));
1172 if (unset_nonblock(*newsock) == -1) {
1176 if (drop_connection(startups) == 1) {
1177 debug("drop connection #%d", startups);
1181 if (pipe(startup_p) == -1) {
1186 if (rexec_flag && socketpair(AF_UNIX,
1187 SOCK_STREAM, 0, config_s) == -1) {
1188 error("reexec socketpair: %s",
1191 close(startup_p[0]);
1192 close(startup_p[1]);
1196 for (j = 0; j < options.max_startups; j++)
1197 if (startup_pipes[j] == -1) {
1198 startup_pipes[j] = startup_p[0];
1199 if (maxfd < startup_p[0])
1200 maxfd = startup_p[0];
1206 * Got connection. Fork a child to handle it, unless
1207 * we are in debugging mode.
1211 * In debugging mode. Close the listening
1212 * socket, and start processing the
1213 * connection without forking.
1215 debug("Server will not fork when running in debugging mode.");
1216 close_listen_socks();
1217 *sock_in = *newsock;
1218 *sock_out = *newsock;
1219 close(startup_p[0]);
1220 close(startup_p[1]);
1224 send_rexec_state(config_s[0],
1232 * Normal production daemon. Fork, and have
1233 * the child process the connection. The
1234 * parent continues listening.
1236 platform_pre_fork();
1237 if ((pid = fork()) == 0) {
1239 * Child. Close the listening and
1240 * max_startup sockets. Start using
1241 * the accepted socket. Reinitialize
1242 * logging (since our pid has changed).
1243 * We break out of the loop to handle
1246 platform_post_fork_child();
1247 startup_pipe = startup_p[1];
1248 close_startup_pipes();
1249 close_listen_socks();
1250 *sock_in = *newsock;
1251 *sock_out = *newsock;
1252 log_init(__progname,
1254 options.log_facility,
1261 /* Parent. Stay in the loop. */
1262 platform_post_fork_parent(pid);
1264 error("fork: %.100s", strerror(errno));
1266 debug("Forked child %ld.", (long)pid);
1268 close(startup_p[1]);
1271 send_rexec_state(config_s[0], &cfg);
1277 * Mark that the key has been used (it
1278 * was "given" to the child).
1280 if ((options.protocol & SSH_PROTO_1) &&
1282 /* Schedule server key regeneration alarm. */
1283 signal(SIGALRM, key_regeneration_alarm);
1284 alarm(options.key_regeneration_time);
1291 * Ensure that our random state differs
1292 * from that of the child
1297 /* child process check (or debug mode) */
1298 if (num_listen_socks < 0)
1305 * Main program for the daemon.
1308 main(int ac, char **av)
1310 extern char *optarg;
1312 int opt, i, j, on = 1;
1313 int sock_in = -1, sock_out = -1, newsock = -1;
1314 const char *remote_ip;
1315 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1317 char *line, *p, *cp;
1318 int config_s[2] = { -1 , -1 };
1319 u_int64_t ibytes, obytes;
1324 #ifdef HAVE_SECUREWARE
1325 (void)set_auth_parameters(ac, av);
1327 __progname = ssh_get_progname(av[0]);
1330 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1333 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1334 for (i = 0; i < ac; i++)
1335 saved_argv[i] = xstrdup(av[i]);
1336 saved_argv[i] = NULL;
1338 #ifndef HAVE_SETPROCTITLE
1339 /* Prepare for later setproctitle emulation */
1340 compat_init_setproctitle(ac, av);
1344 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1345 debug("setgroups(): %.200s", strerror(errno));
1347 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1350 /* Initialize configuration options to their default values. */
1351 initialize_server_options(&options);
1353 /* Parse command-line arguments. */
1354 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1357 options.address_family = AF_INET;
1360 options.address_family = AF_INET6;
1363 config_file_name = optarg;
1366 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1367 fprintf(stderr, "too many host certificates.\n");
1370 options.host_cert_files[options.num_host_cert_files++] =
1371 derelativise_path(optarg);
1374 if (debug_flag == 0) {
1376 options.log_level = SYSLOG_LEVEL_DEBUG1;
1377 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1378 options.log_level++;
1400 options.log_level = SYSLOG_LEVEL_QUIET;
1403 options.server_key_bits = (int)strtonum(optarg, 256,
1407 options.ports_from_cmdline = 1;
1408 if (options.num_ports >= MAX_PORTS) {
1409 fprintf(stderr, "too many ports.\n");
1412 options.ports[options.num_ports++] = a2port(optarg);
1413 if (options.ports[options.num_ports-1] <= 0) {
1414 fprintf(stderr, "Bad port number.\n");
1419 if ((options.login_grace_time = convtime(optarg)) == -1) {
1420 fprintf(stderr, "Invalid login grace time.\n");
1425 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1426 fprintf(stderr, "Invalid key regeneration interval.\n");
1431 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1432 fprintf(stderr, "too many host keys.\n");
1435 options.host_key_files[options.num_host_key_files++] =
1436 derelativise_path(optarg);
1446 while ((p = strsep(&cp, ",")) && *p != '\0') {
1447 if (strncmp(p, "addr=", 5) == 0)
1448 test_addr = xstrdup(p + 5);
1449 else if (strncmp(p, "host=", 5) == 0)
1450 test_host = xstrdup(p + 5);
1451 else if (strncmp(p, "user=", 5) == 0)
1452 test_user = xstrdup(p + 5);
1454 fprintf(stderr, "Invalid test "
1455 "mode specification %s\n", p);
1461 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1462 if (utmp_len > MAXHOSTNAMELEN) {
1463 fprintf(stderr, "Invalid utmp length.\n");
1468 line = xstrdup(optarg);
1469 if (process_server_config_line(&options, line,
1470 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1480 if (rexeced_flag || inetd_flag)
1482 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1483 fatal("sshd re-exec requires execution with an absolute path");
1485 closefrom(REEXEC_MIN_FREE_FD);
1487 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1489 OpenSSL_add_all_algorithms();
1492 * Force logging to stderr until we have loaded the private host
1493 * key (unless started from inetd)
1495 log_init(__progname,
1496 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1497 SYSLOG_LEVEL_INFO : options.log_level,
1498 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1499 SYSLOG_FACILITY_AUTH : options.log_facility,
1500 log_stderr || !inetd_flag);
1503 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1504 * root's environment
1506 if (getenv("KRB5CCNAME") != NULL)
1507 unsetenv("KRB5CCNAME");
1510 /* Cray can define user privs drop all privs now!
1511 * Not needed on PRIV_SU systems!
1516 sensitive_data.server_key = NULL;
1517 sensitive_data.ssh1_host_key = NULL;
1518 sensitive_data.have_ssh1_key = 0;
1519 sensitive_data.have_ssh2_key = 0;
1522 * If we're doing an extended config test, make sure we have all of
1523 * the parameters we need. If we're not doing an extended test,
1524 * do not silently ignore connection test params.
1526 if (test_flag >= 2 &&
1527 (test_user != NULL || test_host != NULL || test_addr != NULL)
1528 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1529 fatal("user, host and addr are all required when testing "
1531 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1533 fatal("Config test connection parameter (-C) provided without "
1536 /* Fetch our configuration */
1539 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1541 load_server_config(config_file_name, &cfg);
1543 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1544 &cfg, NULL, NULL, NULL);
1548 /* Fill in default values for those options not explicitly set. */
1549 fill_default_server_options(&options);
1551 /* challenge-response is implemented via keyboard interactive */
1552 if (options.challenge_response_authentication)
1553 options.kbd_interactive_authentication = 1;
1555 /* set default channel AF */
1556 channel_set_af(options.address_family);
1558 /* Check that there are no remaining arguments. */
1560 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1564 debug("sshd version %.100s", SSH_RELEASE);
1566 /* Store privilege separation user for later use if required. */
1567 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1568 if (use_privsep || options.kerberos_authentication)
1569 fatal("Privilege separation user %s does not exist",
1572 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1573 privsep_pw = pwcopy(privsep_pw);
1574 xfree(privsep_pw->pw_passwd);
1575 privsep_pw->pw_passwd = xstrdup("*");
1579 /* load private host keys */
1580 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1582 for (i = 0; i < options.num_host_key_files; i++)
1583 sensitive_data.host_keys[i] = NULL;
1585 for (i = 0; i < options.num_host_key_files; i++) {
1586 key = key_load_private(options.host_key_files[i], "", NULL);
1587 sensitive_data.host_keys[i] = key;
1589 error("Could not load host key: %s",
1590 options.host_key_files[i]);
1591 sensitive_data.host_keys[i] = NULL;
1594 switch (key->type) {
1596 sensitive_data.ssh1_host_key = key;
1597 sensitive_data.have_ssh1_key = 1;
1602 sensitive_data.have_ssh2_key = 1;
1605 debug("private host key: #%d type %d %s", i, key->type,
1608 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1609 logit("Disabling protocol version 1. Could not load host key");
1610 options.protocol &= ~SSH_PROTO_1;
1612 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1613 logit("Disabling protocol version 2. Could not load host key");
1614 options.protocol &= ~SSH_PROTO_2;
1616 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1617 logit("sshd: no hostkeys available -- exiting.");
1622 * Load certificates. They are stored in an array at identical
1623 * indices to the public keys that they relate to.
1625 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1627 for (i = 0; i < options.num_host_key_files; i++)
1628 sensitive_data.host_certificates[i] = NULL;
1630 for (i = 0; i < options.num_host_cert_files; i++) {
1631 key = key_load_public(options.host_cert_files[i], NULL);
1633 error("Could not load host certificate: %s",
1634 options.host_cert_files[i]);
1637 if (!key_is_cert(key)) {
1638 error("Certificate file is not a certificate: %s",
1639 options.host_cert_files[i]);
1643 /* Find matching private key */
1644 for (j = 0; j < options.num_host_key_files; j++) {
1645 if (key_equal_public(key,
1646 sensitive_data.host_keys[j])) {
1647 sensitive_data.host_certificates[j] = key;
1651 if (j >= options.num_host_key_files) {
1652 error("No matching private key for certificate: %s",
1653 options.host_cert_files[i]);
1657 sensitive_data.host_certificates[j] = key;
1658 debug("host certificate: #%d type %d %s", j, key->type,
1661 /* Check certain values for sanity. */
1662 if (options.protocol & SSH_PROTO_1) {
1663 if (options.server_key_bits < 512 ||
1664 options.server_key_bits > 32768) {
1665 fprintf(stderr, "Bad server key size.\n");
1669 * Check that server and host key lengths differ sufficiently. This
1670 * is necessary to make double encryption work with rsaref. Oh, I
1671 * hate software patents. I dont know if this can go? Niels
1673 if (options.server_key_bits >
1674 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1675 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1676 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1677 SSH_KEY_BITS_RESERVED) {
1678 options.server_key_bits =
1679 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1680 SSH_KEY_BITS_RESERVED;
1681 debug("Forcing server key to %d bits to make it differ from host key.",
1682 options.server_key_bits);
1689 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1690 (S_ISDIR(st.st_mode) == 0))
1691 fatal("Missing privilege separation directory: %s",
1692 _PATH_PRIVSEP_CHROOT_DIR);
1695 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1696 (st.st_uid != getuid () ||
1697 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1699 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1701 fatal("%s must be owned by root and not group or "
1702 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1705 if (test_flag > 1) {
1706 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1707 parse_server_match_config(&options, test_user,
1708 test_host, test_addr);
1709 dump_config(&options);
1712 /* Configuration looks good, so exit if in test mode. */
1717 * Clear out any supplemental groups we may have inherited. This
1718 * prevents inadvertent creation of files with bad modes (in the
1719 * portable version at least, it's certainly possible for PAM
1720 * to create a file, and we can't control the code in every
1721 * module which might be used).
1723 if (setgroups(0, NULL) < 0)
1724 debug("setgroups() failed: %.200s", strerror(errno));
1727 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1728 for (i = 0; i < rexec_argc; i++) {
1729 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1730 rexec_argv[i] = saved_argv[i];
1732 rexec_argv[rexec_argc] = "-R";
1733 rexec_argv[rexec_argc + 1] = NULL;
1736 /* Ensure that umask disallows at least group and world write */
1737 new_umask = umask(0077) | 0022;
1738 (void) umask(new_umask);
1740 /* Initialize the log (it is reinitialized below in case we forked). */
1741 if (debug_flag && (!inetd_flag || rexeced_flag))
1743 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1746 * If not in debugging mode, and not started from inetd, disconnect
1747 * from the controlling terminal, and fork. The original process
1750 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1753 #endif /* TIOCNOTTY */
1754 if (daemon(0, 0) < 0)
1755 fatal("daemon() failed: %.200s", strerror(errno));
1757 /* Disconnect from the controlling tty. */
1759 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1761 (void) ioctl(fd, TIOCNOTTY, NULL);
1764 #endif /* TIOCNOTTY */
1766 /* Reinitialize the log (because of the fork above). */
1767 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1769 /* Avoid killing the process in high-pressure swapping environments. */
1770 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0)
1771 debug("madvise(): %.200s", strerror(errno));
1773 /* Initialize the random number generator. */
1776 /* Chdir to the root directory so that the current disk can be
1777 unmounted if desired. */
1780 /* ignore SIGPIPE */
1781 signal(SIGPIPE, SIG_IGN);
1783 /* Get a connection, either from inetd or a listening TCP socket */
1785 server_accept_inetd(&sock_in, &sock_out);
1787 platform_pre_listen();
1790 if (options.protocol & SSH_PROTO_1)
1791 generate_ephemeral_server_key();
1793 signal(SIGHUP, sighup_handler);
1794 signal(SIGCHLD, main_sigchld_handler);
1795 signal(SIGTERM, sigterm_handler);
1796 signal(SIGQUIT, sigterm_handler);
1799 * Write out the pid file after the sigterm handler
1800 * is setup and the listen sockets are bound
1803 FILE *f = fopen(options.pid_file, "w");
1806 error("Couldn't create pid file \"%s\": %s",
1807 options.pid_file, strerror(errno));
1809 fprintf(f, "%ld\n", (long) getpid());
1814 /* Accept a connection and return in a forked child */
1815 server_accept_loop(&sock_in, &sock_out,
1816 &newsock, config_s);
1819 /* This is the child processing a new connection. */
1820 setproctitle("%s", "[accepted]");
1823 * Create a new session and process group since the 4.4BSD
1824 * setlogin() affects the entire process group. We don't
1825 * want the child to be able to affect the parent.
1827 #if !defined(SSHD_ACQUIRES_CTTY)
1829 * If setsid is called, on some platforms sshd will later acquire a
1830 * controlling terminal which will result in "could not set
1831 * controlling tty" errors.
1833 if (!debug_flag && !inetd_flag && setsid() < 0)
1834 error("setsid: %.100s", strerror(errno));
1840 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1841 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1842 dup2(newsock, STDIN_FILENO);
1843 dup2(STDIN_FILENO, STDOUT_FILENO);
1844 if (startup_pipe == -1)
1845 close(REEXEC_STARTUP_PIPE_FD);
1847 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1849 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1851 if (startup_pipe != -1)
1852 close(startup_pipe);
1854 execv(rexec_argv[0], rexec_argv);
1856 /* Reexec has failed, fall back and continue */
1857 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1858 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1859 log_init(__progname, options.log_level,
1860 options.log_facility, log_stderr);
1863 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1865 close(REEXEC_CONFIG_PASS_FD);
1866 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1867 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1868 dup2(fd, STDIN_FILENO);
1869 dup2(fd, STDOUT_FILENO);
1870 if (fd > STDERR_FILENO)
1873 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1874 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1877 /* Executed child processes don't need these. */
1878 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1879 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1882 * Disable the key regeneration alarm. We will not regenerate the
1883 * key since we are no longer in a position to give it to anyone. We
1884 * will not restart on SIGHUP since it no longer makes sense.
1887 signal(SIGALRM, SIG_DFL);
1888 signal(SIGHUP, SIG_DFL);
1889 signal(SIGTERM, SIG_DFL);
1890 signal(SIGQUIT, SIG_DFL);
1891 signal(SIGCHLD, SIG_DFL);
1892 signal(SIGINT, SIG_DFL);
1896 * Initialize the resolver. This may not happen automatically
1897 * before privsep chroot().
1899 if ((_res.options & RES_INIT) == 0) {
1900 debug("res_init()");
1905 * Force GSS-API to parse its configuration and load any
1906 * mechanism plugins.
1910 OM_uint32 minor_status;
1911 gss_indicate_mechs(&minor_status, &mechs);
1912 gss_release_oid_set(&minor_status, &mechs);
1918 * Register our connection. This turns encryption off because we do
1921 packet_set_connection(sock_in, sock_out);
1922 packet_set_server();
1924 /* Set SO_KEEPALIVE if requested. */
1925 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1926 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1927 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1929 if ((remote_port = get_remote_port()) < 0) {
1930 debug("get_remote_port failed");
1935 * We use get_canonical_hostname with usedns = 0 instead of
1936 * get_remote_ipaddr here so IP options will be checked.
1938 (void) get_canonical_hostname(0);
1940 * The rest of the code depends on the fact that
1941 * get_remote_ipaddr() caches the remote ip, even if
1942 * the socket goes away.
1944 remote_ip = get_remote_ipaddr();
1946 #ifdef SSH_AUDIT_EVENTS
1947 audit_connection_from(remote_ip, remote_port);
1950 allow_severity = options.log_facility|LOG_INFO;
1951 deny_severity = options.log_facility|LOG_WARNING;
1952 /* Check whether logins are denied from this host. */
1953 if (packet_connection_is_on_socket()) {
1954 struct request_info req;
1956 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1959 if (!hosts_access(&req)) {
1960 debug("Connection refused by tcp wrapper");
1963 fatal("libwrap refuse returns");
1966 #endif /* LIBWRAP */
1968 /* Log the connection. */
1969 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1971 /* Set HPN options for the child. */
1972 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1975 * We don't want to listen forever unless the other side
1976 * successfully authenticates itself. So we set up an alarm which is
1977 * cleared after successful authentication. A limit of zero
1978 * indicates no limit. Note that we don't set the alarm in debugging
1979 * mode; it is just annoying to have the server exit just when you
1980 * are about to discover the bug.
1982 signal(SIGALRM, grace_alarm_handler);
1984 alarm(options.login_grace_time);
1986 sshd_exchange_identification(sock_in, sock_out);
1988 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1989 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1990 generate_ephemeral_server_key();
1992 packet_set_nonblocking();
1994 /* allocate authentication context */
1995 authctxt = xcalloc(1, sizeof(*authctxt));
1997 authctxt->loginmsg = &loginmsg;
1999 /* XXX global for cleanup, access from other modules */
2000 the_authctxt = authctxt;
2002 /* prepare buffer to collect messages to display to user after login */
2003 buffer_init(&loginmsg);
2007 if (privsep_preauth(authctxt) == 1)
2010 /* perform the key exchange */
2011 /* authenticate user and start session */
2014 do_authentication2(authctxt);
2017 do_authentication(authctxt);
2020 * If we use privilege separation, the unprivileged child transfers
2021 * the current keystate and exits
2024 mm_send_keystate(pmonitor);
2030 * Cancel the alarm we set to limit the time taken for
2034 signal(SIGALRM, SIG_DFL);
2035 authctxt->authenticated = 1;
2036 if (startup_pipe != -1) {
2037 close(startup_pipe);
2041 #ifdef SSH_AUDIT_EVENTS
2042 audit_event(SSH_AUTH_SUCCESS);
2046 if (options.gss_authentication) {
2047 temporarily_use_uid(authctxt->pw);
2048 ssh_gssapi_storecreds();
2053 if (options.use_pam) {
2060 * In privilege separation, we fork another child and prepare
2061 * file descriptor passing.
2064 privsep_postauth(authctxt);
2065 /* the monitor process [priv] will not return */
2067 destroy_sensitive_data();
2070 packet_set_timeout(options.client_alive_interval,
2071 options.client_alive_count_max);
2073 /* Start session. */
2074 do_authenticated(authctxt);
2076 /* The connection has been terminated. */
2077 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2078 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2079 verbose("Transferred: sent %llu, received %llu bytes",
2080 (unsigned long long)obytes, (unsigned long long)ibytes);
2082 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2085 if (options.use_pam)
2087 #endif /* USE_PAM */
2089 #ifdef SSH_AUDIT_EVENTS
2090 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2102 * Decrypt session_key_int using our private server key and private host key
2103 * (key with larger modulus first).
2106 ssh1_session_key(BIGNUM *session_key_int)
2110 if (BN_cmp(sensitive_data.server_key->rsa->n,
2111 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2112 /* Server key has bigger modulus. */
2113 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2114 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2115 SSH_KEY_BITS_RESERVED) {
2116 fatal("do_connection: %s: "
2117 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2118 get_remote_ipaddr(),
2119 BN_num_bits(sensitive_data.server_key->rsa->n),
2120 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2121 SSH_KEY_BITS_RESERVED);
2123 if (rsa_private_decrypt(session_key_int, session_key_int,
2124 sensitive_data.server_key->rsa) <= 0)
2126 if (rsa_private_decrypt(session_key_int, session_key_int,
2127 sensitive_data.ssh1_host_key->rsa) <= 0)
2130 /* Host key has bigger modulus (or they are equal). */
2131 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2132 BN_num_bits(sensitive_data.server_key->rsa->n) +
2133 SSH_KEY_BITS_RESERVED) {
2134 fatal("do_connection: %s: "
2135 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2136 get_remote_ipaddr(),
2137 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2138 BN_num_bits(sensitive_data.server_key->rsa->n),
2139 SSH_KEY_BITS_RESERVED);
2141 if (rsa_private_decrypt(session_key_int, session_key_int,
2142 sensitive_data.ssh1_host_key->rsa) < 0)
2144 if (rsa_private_decrypt(session_key_int, session_key_int,
2145 sensitive_data.server_key->rsa) < 0)
2158 BIGNUM *session_key_int;
2159 u_char session_key[SSH_SESSION_KEY_LENGTH];
2161 u_int cipher_type, auth_mask, protocol_flags;
2164 * Generate check bytes that the client must send back in the user
2165 * packet in order for it to be accepted; this is used to defy ip
2166 * spoofing attacks. Note that this only works against somebody
2167 * doing IP spoofing from a remote machine; any machine on the local
2168 * network can still see outgoing packets and catch the random
2169 * cookie. This only affects rhosts authentication, and this is one
2170 * of the reasons why it is inherently insecure.
2172 arc4random_buf(cookie, sizeof(cookie));
2175 * Send our public key. We include in the packet 64 bits of random
2176 * data that must be matched in the reply in order to prevent IP
2179 packet_start(SSH_SMSG_PUBLIC_KEY);
2180 for (i = 0; i < 8; i++)
2181 packet_put_char(cookie[i]);
2183 /* Store our public server RSA key. */
2184 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2185 packet_put_bignum(sensitive_data.server_key->rsa->e);
2186 packet_put_bignum(sensitive_data.server_key->rsa->n);
2188 /* Store our public host RSA key. */
2189 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2190 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2191 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2193 /* Put protocol flags. */
2194 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2196 /* Declare which ciphers we support. */
2197 packet_put_int(cipher_mask_ssh1(0));
2199 /* Declare supported authentication types. */
2201 if (options.rhosts_rsa_authentication)
2202 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2203 if (options.rsa_authentication)
2204 auth_mask |= 1 << SSH_AUTH_RSA;
2205 if (options.challenge_response_authentication == 1)
2206 auth_mask |= 1 << SSH_AUTH_TIS;
2207 if (options.password_authentication)
2208 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2209 packet_put_int(auth_mask);
2211 /* Send the packet and wait for it to be sent. */
2213 packet_write_wait();
2215 debug("Sent %d bit server key and %d bit host key.",
2216 BN_num_bits(sensitive_data.server_key->rsa->n),
2217 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2219 /* Read clients reply (cipher type and session key). */
2220 packet_read_expect(SSH_CMSG_SESSION_KEY);
2222 /* Get cipher type and check whether we accept this. */
2223 cipher_type = packet_get_char();
2225 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2226 packet_disconnect("Warning: client selects unsupported cipher.");
2228 /* Get check bytes from the packet. These must match those we
2229 sent earlier with the public key packet. */
2230 for (i = 0; i < 8; i++)
2231 if (cookie[i] != packet_get_char())
2232 packet_disconnect("IP Spoofing check bytes do not match.");
2234 debug("Encryption type: %.200s", cipher_name(cipher_type));
2236 /* Get the encrypted integer. */
2237 if ((session_key_int = BN_new()) == NULL)
2238 fatal("do_ssh1_kex: BN_new failed");
2239 packet_get_bignum(session_key_int);
2241 protocol_flags = packet_get_int();
2242 packet_set_protocol_flags(protocol_flags);
2245 /* Decrypt session_key_int using host/server keys */
2246 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2249 * Extract session key from the decrypted integer. The key is in the
2250 * least significant 256 bits of the integer; the first byte of the
2251 * key is in the highest bits.
2254 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2255 len = BN_num_bytes(session_key_int);
2256 if (len < 0 || (u_int)len > sizeof(session_key)) {
2257 error("do_ssh1_kex: bad session key len from %s: "
2258 "session_key_int %d > sizeof(session_key) %lu",
2259 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2262 memset(session_key, 0, sizeof(session_key));
2263 BN_bn2bin(session_key_int,
2264 session_key + sizeof(session_key) - len);
2266 derive_ssh1_session_id(
2267 sensitive_data.ssh1_host_key->rsa->n,
2268 sensitive_data.server_key->rsa->n,
2269 cookie, session_id);
2271 * Xor the first 16 bytes of the session key with the
2274 for (i = 0; i < 16; i++)
2275 session_key[i] ^= session_id[i];
2279 int bytes = BN_num_bytes(session_key_int);
2280 u_char *buf = xmalloc(bytes);
2283 logit("do_connection: generating a fake encryption key");
2284 BN_bn2bin(session_key_int, buf);
2286 MD5_Update(&md, buf, bytes);
2287 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2288 MD5_Final(session_key, &md);
2290 MD5_Update(&md, session_key, 16);
2291 MD5_Update(&md, buf, bytes);
2292 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2293 MD5_Final(session_key + 16, &md);
2294 memset(buf, 0, bytes);
2296 for (i = 0; i < 16; i++)
2297 session_id[i] = session_key[i] ^ session_key[i + 16];
2299 /* Destroy the private and public keys. No longer. */
2300 destroy_sensitive_data();
2303 mm_ssh1_session_id(session_id);
2305 /* Destroy the decrypted integer. It is no longer needed. */
2306 BN_clear_free(session_key_int);
2308 /* Set the session key. From this on all communications will be encrypted. */
2309 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2311 /* Destroy our copy of the session key. It is no longer needed. */
2312 memset(session_key, 0, sizeof(session_key));
2314 debug("Received session key; encryption turned on.");
2316 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2317 packet_start(SSH_SMSG_SUCCESS);
2319 packet_write_wait();
2323 * SSH2 key exchange: diffie-hellman-group1-sha1
2330 if (options.ciphers != NULL) {
2331 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2332 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2333 #ifdef NONE_CIPHER_ENABLED
2334 } else if (options.none_enabled == 1) {
2335 debug ("WARNING: None cipher enabled");
2336 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2337 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE;
2340 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2341 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2342 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2343 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2345 if (options.macs != NULL) {
2346 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2347 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2349 if (options.compression == COMP_NONE) {
2350 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2351 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2352 } else if (options.compression == COMP_DELAYED) {
2353 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2354 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2356 if (options.kex_algorithms != NULL)
2357 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
2359 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2361 /* start key exchange */
2362 kex = kex_setup(myproposal);
2363 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2364 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2365 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2366 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2367 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2369 kex->client_version_string=client_version_string;
2370 kex->server_version_string=server_version_string;
2371 kex->load_host_public_key=&get_hostkey_public_by_type;
2372 kex->load_host_private_key=&get_hostkey_private_by_type;
2373 kex->host_key_index=&get_hostkey_index;
2377 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2379 session_id2 = kex->session_id;
2380 session_id2_len = kex->session_id_len;
2383 /* send 1st encrypted/maced/compressed message */
2384 packet_start(SSH2_MSG_IGNORE);
2385 packet_put_cstring("markus");
2387 packet_write_wait();
2392 /* server specific fatal cleanup */
2397 do_cleanup(the_authctxt);
2398 #ifdef SSH_AUDIT_EVENTS
2399 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2400 if (!use_privsep || mm_is_monitor())
2401 audit_event(SSH_CONNECTION_ABANDON);