1 /* $OpenBSD: sshd.c,v 1.393 2012/07/10 02:19:15 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>
102 #include "myproposal.h"
103 #include "authfile.h"
104 #include "pathnames.h"
105 #include "atomicio.h"
106 #include "canohost.h"
107 #include "hostfile.h"
111 #include "dispatch.h"
112 #include "channels.h"
114 #include "monitor_mm.h"
119 #include "monitor_wrap.h"
121 #include "ssh-sandbox.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)
141 extern char *__progname;
143 /* Server configuration options. */
144 ServerOptions options;
146 /* Name of the server configuration file. */
147 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
150 * Debug mode flag. This can be set on the command line. If debug
151 * mode is enabled, extra debugging output will be sent to the system
152 * log, the daemon will not go to background, and will exit after processing
153 * the first connection.
157 /* Flag indicating that the daemon should only test the configuration and keys. */
160 /* Flag indicating that the daemon is being started from inetd. */
163 /* Flag indicating that sshd should not detach and become a daemon. */
164 int no_daemon_flag = 0;
166 /* debug goes to stderr unless inetd_flag is set */
169 /* Saved arguments to main(). */
174 int rexeced_flag = 0;
180 * The sockets that the server is listening; this is used in the SIGHUP
183 #define MAX_LISTEN_SOCKS 16
184 int listen_socks[MAX_LISTEN_SOCKS];
185 int num_listen_socks = 0;
188 * the client's version string, passed by sshd2 in compat mode. if != NULL,
189 * sshd will skip the version-number exchange
191 char *client_version_string = NULL;
192 char *server_version_string = NULL;
194 /* for rekeying XXX fixme */
198 * Any really sensitive data in the application is contained in this
199 * structure. The idea is that this structure could be locked into memory so
200 * that the pages do not get written into swap. However, there are some
201 * problems. The private key contains BIGNUMs, and we do not (in principle)
202 * have access to the internals of them, and locking just the structure is
203 * not very useful. Currently, memory locking is not implemented.
206 Key *server_key; /* ephemeral server key */
207 Key *ssh1_host_key; /* ssh1 host key */
208 Key **host_keys; /* all private host keys */
209 Key **host_certificates; /* all public host certificates */
212 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
216 * Flag indicating whether the RSA server key needs to be regenerated.
217 * Is set in the SIGALRM handler and cleared when the key is regenerated.
219 static volatile sig_atomic_t key_do_regen = 0;
221 /* This is set to true when a signal is received. */
222 static volatile sig_atomic_t received_sighup = 0;
223 static volatile sig_atomic_t received_sigterm = 0;
225 /* session identifier, used by RSA-auth */
226 u_char session_id[16];
229 u_char *session_id2 = NULL;
230 u_int session_id2_len = 0;
232 /* record remote hostname or ip */
233 u_int utmp_len = MAXHOSTNAMELEN;
235 /* options.max_startup sized array of fd ints */
236 int *startup_pipes = NULL;
237 int startup_pipe; /* in child */
239 /* variables used for privilege separation */
240 int use_privsep = -1;
241 struct monitor *pmonitor = NULL;
242 int privsep_is_preauth = 1;
244 /* global authentication context */
245 Authctxt *the_authctxt = NULL;
247 /* sshd_config buffer */
250 /* message to be displayed after login */
253 /* Unprivileged user */
254 struct passwd *privsep_pw = NULL;
256 /* Prototypes for various functions defined later in this file. */
257 void destroy_sensitive_data(void);
258 void demote_sensitive_data(void);
260 static void do_ssh1_kex(void);
261 static void do_ssh2_kex(void);
264 * Close all listening sockets
267 close_listen_socks(void)
271 for (i = 0; i < num_listen_socks; i++)
272 close(listen_socks[i]);
273 num_listen_socks = -1;
277 close_startup_pipes(void)
282 for (i = 0; i < options.max_startups; i++)
283 if (startup_pipes[i] != -1)
284 close(startup_pipes[i]);
288 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
289 * the effect is to reread the configuration file (and to regenerate
295 sighup_handler(int sig)
297 int save_errno = errno;
300 signal(SIGHUP, sighup_handler);
305 * Called from the main program after receiving SIGHUP.
306 * Restarts the server.
311 logit("Received SIGHUP; restarting.");
312 close_listen_socks();
313 close_startup_pipes();
314 alarm(0); /* alarm timer persists across exec */
315 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
316 execv(saved_argv[0], saved_argv);
317 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
323 * Generic signal handler for terminating signals in the master daemon.
327 sigterm_handler(int sig)
329 received_sigterm = sig;
333 * SIGCHLD handler. This is called whenever a child dies. This will then
334 * reap any zombies left by exited children.
338 main_sigchld_handler(int sig)
340 int save_errno = errno;
344 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
345 (pid < 0 && errno == EINTR))
348 signal(SIGCHLD, main_sigchld_handler);
353 * Signal handler for the alarm after the login grace period has expired.
357 grace_alarm_handler(int sig)
359 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
360 kill(pmonitor->m_pid, SIGALRM);
362 /* Log error and exit. */
363 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
367 * Signal handler for the key regeneration alarm. Note that this
368 * alarm only occurs in the daemon waiting for connections, and it does not
369 * do anything with the private key or random state before forking.
370 * Thus there should be no concurrency control/asynchronous execution
374 generate_ephemeral_server_key(void)
376 verbose("Generating %s%d bit RSA key.",
377 sensitive_data.server_key ? "new " : "", options.server_key_bits);
378 if (sensitive_data.server_key != NULL)
379 key_free(sensitive_data.server_key);
380 sensitive_data.server_key = key_generate(KEY_RSA1,
381 options.server_key_bits);
382 verbose("RSA key generation complete.");
384 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
390 key_regeneration_alarm(int sig)
392 int save_errno = errno;
394 signal(SIGALRM, SIG_DFL);
400 sshd_exchange_identification(int sock_in, int sock_out)
404 int remote_major, remote_minor;
406 char *s, *newline = "\n";
407 char buf[256]; /* Must not be larger than remote_version. */
408 char remote_version[256]; /* Must be at least as big as buf. */
410 if ((options.protocol & SSH_PROTO_1) &&
411 (options.protocol & SSH_PROTO_2)) {
412 major = PROTOCOL_MAJOR_1;
414 } else if (options.protocol & SSH_PROTO_2) {
415 major = PROTOCOL_MAJOR_2;
416 minor = PROTOCOL_MINOR_2;
419 major = PROTOCOL_MAJOR_1;
420 minor = PROTOCOL_MINOR_1;
423 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s",
424 major, minor, SSH_VERSION,
425 *options.version_addendum == '\0' ? "" : " ",
426 options.version_addendum, newline);
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);
477 compat_datafellows(remote_version);
479 if (datafellows & SSH_BUG_PROBE) {
480 logit("probed from %s with %s. Don't panic.",
481 get_remote_ipaddr(), client_version_string);
485 if (datafellows & SSH_BUG_SCANNER) {
486 logit("scanned from %s with %s. Don't panic.",
487 get_remote_ipaddr(), client_version_string);
492 switch (remote_major) {
494 if (remote_minor == 99) {
495 if (options.protocol & SSH_PROTO_2)
501 if (!(options.protocol & SSH_PROTO_1)) {
505 if (remote_minor < 3) {
506 packet_disconnect("Your ssh version is too old and "
507 "is no longer supported. Please install a newer version.");
508 } else if (remote_minor == 3) {
509 /* note that this disables agent-forwarding */
514 if (options.protocol & SSH_PROTO_2) {
523 chop(server_version_string);
524 debug("Local version string %.200s", server_version_string);
527 s = "Protocol major versions differ.\n";
528 (void) atomicio(vwrite, sock_out, s, strlen(s));
531 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
533 server_version_string, client_version_string);
538 /* Destroy the host and server keys. They will no longer be needed. */
540 destroy_sensitive_data(void)
544 if (sensitive_data.server_key) {
545 key_free(sensitive_data.server_key);
546 sensitive_data.server_key = NULL;
548 for (i = 0; i < options.num_host_key_files; i++) {
549 if (sensitive_data.host_keys[i]) {
550 key_free(sensitive_data.host_keys[i]);
551 sensitive_data.host_keys[i] = NULL;
553 if (sensitive_data.host_certificates[i]) {
554 key_free(sensitive_data.host_certificates[i]);
555 sensitive_data.host_certificates[i] = NULL;
558 sensitive_data.ssh1_host_key = NULL;
559 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
562 /* Demote private to public keys for network child */
564 demote_sensitive_data(void)
569 if (sensitive_data.server_key) {
570 tmp = key_demote(sensitive_data.server_key);
571 key_free(sensitive_data.server_key);
572 sensitive_data.server_key = tmp;
575 for (i = 0; i < options.num_host_key_files; i++) {
576 if (sensitive_data.host_keys[i]) {
577 tmp = key_demote(sensitive_data.host_keys[i]);
578 key_free(sensitive_data.host_keys[i]);
579 sensitive_data.host_keys[i] = tmp;
580 if (tmp->type == KEY_RSA1)
581 sensitive_data.ssh1_host_key = tmp;
583 /* Certs do not need demotion */
586 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
590 privsep_preauth_child(void)
595 /* Enable challenge-response authentication for privilege separation */
596 privsep_challenge_enable();
599 arc4random_buf(rnd, sizeof(rnd));
600 RAND_seed(rnd, sizeof(rnd));
602 /* Demote the private keys to public keys. */
603 demote_sensitive_data();
605 /* Change our root directory */
606 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
607 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
609 if (chdir("/") == -1)
610 fatal("chdir(\"/\"): %s", strerror(errno));
612 /* Drop our privileges */
613 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
614 (u_int)privsep_pw->pw_gid);
616 /* XXX not ready, too heavy after chroot */
617 do_setusercontext(privsep_pw);
619 gidset[0] = privsep_pw->pw_gid;
620 if (setgroups(1, gidset) < 0)
621 fatal("setgroups: %.100s", strerror(errno));
622 permanently_set_uid(privsep_pw);
627 privsep_preauth(Authctxt *authctxt)
631 struct ssh_sandbox *box = NULL;
633 /* Set up unprivileged child process to deal with network data */
634 pmonitor = monitor_init();
635 /* Store a pointer to the kex for later rekeying */
636 pmonitor->m_pkex = &xxx_kex;
638 if (use_privsep == PRIVSEP_ON)
639 box = ssh_sandbox_init();
642 fatal("fork of unprivileged child failed");
643 } else if (pid != 0) {
644 debug2("Network child is on pid %ld", (long)pid);
646 pmonitor->m_pid = pid;
648 ssh_sandbox_parent_preauth(box, pid);
649 monitor_child_preauth(authctxt, pmonitor);
652 monitor_sync(pmonitor);
654 /* Wait for the child's exit status */
655 while (waitpid(pid, &status, 0) < 0) {
658 pmonitor->m_pid = -1;
659 fatal("%s: waitpid: %s", __func__, strerror(errno));
661 privsep_is_preauth = 0;
662 pmonitor->m_pid = -1;
663 if (WIFEXITED(status)) {
664 if (WEXITSTATUS(status) != 0)
665 fatal("%s: preauth child exited with status %d",
666 __func__, WEXITSTATUS(status));
667 } else if (WIFSIGNALED(status))
668 fatal("%s: preauth child terminated by signal %d",
669 __func__, WTERMSIG(status));
671 ssh_sandbox_parent_finish(box);
675 close(pmonitor->m_sendfd);
676 close(pmonitor->m_log_recvfd);
678 /* Arrange for logging to be sent to the monitor */
679 set_log_handler(mm_log_handler, pmonitor);
681 /* Demote the child */
682 if (getuid() == 0 || geteuid() == 0)
683 privsep_preauth_child();
684 setproctitle("%s", "[net]");
686 ssh_sandbox_child(box);
693 privsep_postauth(Authctxt *authctxt)
697 #ifdef DISABLE_FD_PASSING
700 if (authctxt->pw->pw_uid == 0 || options.use_login) {
702 /* File descriptor passing is broken or root login */
707 /* New socket pair */
708 monitor_reinit(pmonitor);
710 pmonitor->m_pid = fork();
711 if (pmonitor->m_pid == -1)
712 fatal("fork of unprivileged child failed");
713 else if (pmonitor->m_pid != 0) {
714 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
715 buffer_clear(&loginmsg);
716 monitor_child_postauth(pmonitor);
724 close(pmonitor->m_sendfd);
725 pmonitor->m_sendfd = -1;
727 /* Demote the private keys to public keys. */
728 demote_sensitive_data();
731 arc4random_buf(rnd, sizeof(rnd));
732 RAND_seed(rnd, sizeof(rnd));
734 /* Drop privileges */
735 do_setusercontext(authctxt->pw);
738 /* It is safe now to apply the key state */
739 monitor_apply_keystate(pmonitor);
742 * Tell the packet layer that authentication was successful, since
743 * this information is not part of the key state.
745 packet_set_authenticated();
749 list_hostkey_types(void)
758 for (i = 0; i < options.num_host_key_files; i++) {
759 key = sensitive_data.host_keys[i];
766 if (buffer_len(&b) > 0)
767 buffer_append(&b, ",", 1);
768 p = key_ssh_name(key);
769 buffer_append(&b, p, strlen(p));
772 /* If the private key has a cert peer, then list that too */
773 key = sensitive_data.host_certificates[i];
777 case KEY_RSA_CERT_V00:
778 case KEY_DSA_CERT_V00:
782 if (buffer_len(&b) > 0)
783 buffer_append(&b, ",", 1);
784 p = key_ssh_name(key);
785 buffer_append(&b, p, strlen(p));
789 buffer_append(&b, "\0", 1);
790 ret = xstrdup(buffer_ptr(&b));
792 debug("list_hostkey_types: %s", ret);
797 get_hostkey_by_type(int type, int need_private)
802 for (i = 0; i < options.num_host_key_files; i++) {
804 case KEY_RSA_CERT_V00:
805 case KEY_DSA_CERT_V00:
809 key = sensitive_data.host_certificates[i];
812 key = sensitive_data.host_keys[i];
815 if (key != NULL && key->type == type)
816 return need_private ?
817 sensitive_data.host_keys[i] : key;
823 get_hostkey_public_by_type(int type)
825 return get_hostkey_by_type(type, 0);
829 get_hostkey_private_by_type(int type)
831 return get_hostkey_by_type(type, 1);
835 get_hostkey_by_index(int ind)
837 if (ind < 0 || ind >= options.num_host_key_files)
839 return (sensitive_data.host_keys[ind]);
843 get_hostkey_index(Key *key)
847 for (i = 0; i < options.num_host_key_files; i++) {
848 if (key_is_cert(key)) {
849 if (key == sensitive_data.host_certificates[i])
852 if (key == sensitive_data.host_keys[i])
860 * returns 1 if connection should be dropped, 0 otherwise.
861 * dropping starts at connection #max_startups_begin with a probability
862 * of (max_startups_rate/100). the probability increases linearly until
863 * all connections are dropped for startups > max_startups
866 drop_connection(int startups)
870 if (startups < options.max_startups_begin)
872 if (startups >= options.max_startups)
874 if (options.max_startups_rate == 100)
877 p = 100 - options.max_startups_rate;
878 p *= startups - options.max_startups_begin;
879 p /= options.max_startups - options.max_startups_begin;
880 p += options.max_startups_rate;
881 r = arc4random_uniform(100);
883 debug("drop_connection: p %d, r %d", p, r);
884 return (r < p) ? 1 : 0;
890 fprintf(stderr, "%s, %s\n",
891 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
893 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
894 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
895 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
901 send_rexec_state(int fd, Buffer *conf)
905 debug3("%s: entering fd = %d config len %d", __func__, fd,
909 * Protocol from reexec master to child:
910 * string configuration
911 * u_int ephemeral_key_follows
912 * bignum e (only if ephemeral_key_follows == 1)
918 * string rngseed (only if OpenSSL is not self-seeded)
921 buffer_put_cstring(&m, buffer_ptr(conf));
923 if (sensitive_data.server_key != NULL &&
924 sensitive_data.server_key->type == KEY_RSA1) {
925 buffer_put_int(&m, 1);
926 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
927 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
928 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
929 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
930 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
931 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
933 buffer_put_int(&m, 0);
935 #ifndef OPENSSL_PRNG_ONLY
936 rexec_send_rng_seed(&m);
939 if (ssh_msg_send(fd, 0, &m) == -1)
940 fatal("%s: ssh_msg_send failed", __func__);
944 debug3("%s: done", __func__);
948 recv_rexec_state(int fd, Buffer *conf)
954 debug3("%s: entering fd = %d", __func__, fd);
958 if (ssh_msg_recv(fd, &m) == -1)
959 fatal("%s: ssh_msg_recv failed", __func__);
960 if (buffer_get_char(&m) != 0)
961 fatal("%s: rexec version mismatch", __func__);
963 cp = buffer_get_string(&m, &len);
965 buffer_append(conf, cp, len + 1);
968 if (buffer_get_int(&m)) {
969 if (sensitive_data.server_key != NULL)
970 key_free(sensitive_data.server_key);
971 sensitive_data.server_key = key_new_private(KEY_RSA1);
972 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
973 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
974 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
975 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
976 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
977 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
978 rsa_generate_additional_parameters(
979 sensitive_data.server_key->rsa);
982 #ifndef OPENSSL_PRNG_ONLY
983 rexec_recv_rng_seed(&m);
988 debug3("%s: done", __func__);
991 /* Accept a connection from inetd */
993 server_accept_inetd(int *sock_in, int *sock_out)
999 close(REEXEC_CONFIG_PASS_FD);
1000 *sock_in = *sock_out = dup(STDIN_FILENO);
1002 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1003 close(REEXEC_STARTUP_PIPE_FD);
1006 *sock_in = dup(STDIN_FILENO);
1007 *sock_out = dup(STDOUT_FILENO);
1010 * We intentionally do not close the descriptors 0, 1, and 2
1011 * as our code for setting the descriptors won't work if
1012 * ttyfd happens to be one of those.
1014 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1015 dup2(fd, STDIN_FILENO);
1016 dup2(fd, STDOUT_FILENO);
1017 if (fd > STDOUT_FILENO)
1020 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1024 * Listen for TCP connections
1029 int ret, listen_sock, on = 1;
1030 struct addrinfo *ai;
1031 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1033 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1034 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1036 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1037 fatal("Too many listen sockets. "
1038 "Enlarge MAX_LISTEN_SOCKS");
1039 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1040 ntop, sizeof(ntop), strport, sizeof(strport),
1041 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1042 error("getnameinfo failed: %.100s",
1043 ssh_gai_strerror(ret));
1046 /* Create socket for listening. */
1047 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1049 if (listen_sock < 0) {
1050 /* kernel may not support ipv6 */
1051 verbose("socket: %.100s", strerror(errno));
1054 if (set_nonblock(listen_sock) == -1) {
1059 * Set socket options.
1060 * Allow local port reuse in TIME_WAIT.
1062 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1063 &on, sizeof(on)) == -1)
1064 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1066 /* Only communicate in IPv6 over AF_INET6 sockets. */
1067 if (ai->ai_family == AF_INET6)
1068 sock_set_v6only(listen_sock);
1070 debug("Bind to port %s on %s.", strport, ntop);
1072 /* Bind the socket to the desired port. */
1073 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1074 error("Bind to port %s on %s failed: %.200s.",
1075 strport, ntop, strerror(errno));
1079 listen_socks[num_listen_socks] = listen_sock;
1082 /* Start listening on the port. */
1083 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1084 fatal("listen on [%s]:%s: %.100s",
1085 ntop, strport, strerror(errno));
1086 logit("Server listening on %s port %s.", ntop, strport);
1088 freeaddrinfo(options.listen_addrs);
1090 if (!num_listen_socks)
1091 fatal("Cannot bind any address.");
1095 * The main TCP accept loop. Note that, for the non-debug case, returns
1096 * from this function are in a forked subprocess.
1099 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1102 int i, j, ret, maxfd;
1103 int key_used = 0, startups = 0;
1104 int startup_p[2] = { -1 , -1 };
1105 struct sockaddr_storage from;
1109 /* setup fd set for accept */
1112 for (i = 0; i < num_listen_socks; i++)
1113 if (listen_socks[i] > maxfd)
1114 maxfd = listen_socks[i];
1115 /* pipes connected to unauthenticated childs */
1116 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1117 for (i = 0; i < options.max_startups; i++)
1118 startup_pipes[i] = -1;
1121 * Stay listening for connections until the system crashes or
1122 * the daemon is killed with a signal.
1125 if (received_sighup)
1129 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1132 for (i = 0; i < num_listen_socks; i++)
1133 FD_SET(listen_socks[i], fdset);
1134 for (i = 0; i < options.max_startups; i++)
1135 if (startup_pipes[i] != -1)
1136 FD_SET(startup_pipes[i], fdset);
1138 /* Wait in select until there is a connection. */
1139 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1140 if (ret < 0 && errno != EINTR)
1141 error("select: %.100s", strerror(errno));
1142 if (received_sigterm) {
1143 logit("Received signal %d; terminating.",
1144 (int) received_sigterm);
1145 close_listen_socks();
1146 unlink(options.pid_file);
1147 exit(received_sigterm == SIGTERM ? 0 : 255);
1149 if (key_used && key_do_regen) {
1150 generate_ephemeral_server_key();
1157 for (i = 0; i < options.max_startups; i++)
1158 if (startup_pipes[i] != -1 &&
1159 FD_ISSET(startup_pipes[i], fdset)) {
1161 * the read end of the pipe is ready
1162 * if the child has closed the pipe
1163 * after successful authentication
1164 * or if the child has died
1166 close(startup_pipes[i]);
1167 startup_pipes[i] = -1;
1170 for (i = 0; i < num_listen_socks; i++) {
1171 if (!FD_ISSET(listen_socks[i], fdset))
1173 fromlen = sizeof(from);
1174 *newsock = accept(listen_socks[i],
1175 (struct sockaddr *)&from, &fromlen);
1177 if (errno != EINTR && errno != EAGAIN &&
1178 errno != EWOULDBLOCK)
1179 error("accept: %.100s",
1181 if (errno == EMFILE || errno == ENFILE)
1185 if (unset_nonblock(*newsock) == -1) {
1189 if (drop_connection(startups) == 1) {
1190 debug("drop connection #%d", startups);
1194 if (pipe(startup_p) == -1) {
1199 if (rexec_flag && socketpair(AF_UNIX,
1200 SOCK_STREAM, 0, config_s) == -1) {
1201 error("reexec socketpair: %s",
1204 close(startup_p[0]);
1205 close(startup_p[1]);
1209 for (j = 0; j < options.max_startups; j++)
1210 if (startup_pipes[j] == -1) {
1211 startup_pipes[j] = startup_p[0];
1212 if (maxfd < startup_p[0])
1213 maxfd = startup_p[0];
1219 * Got connection. Fork a child to handle it, unless
1220 * we are in debugging mode.
1224 * In debugging mode. Close the listening
1225 * socket, and start processing the
1226 * connection without forking.
1228 debug("Server will not fork when running in debugging mode.");
1229 close_listen_socks();
1230 *sock_in = *newsock;
1231 *sock_out = *newsock;
1232 close(startup_p[0]);
1233 close(startup_p[1]);
1237 send_rexec_state(config_s[0],
1245 * Normal production daemon. Fork, and have
1246 * the child process the connection. The
1247 * parent continues listening.
1249 platform_pre_fork();
1250 if ((pid = fork()) == 0) {
1252 * Child. Close the listening and
1253 * max_startup sockets. Start using
1254 * the accepted socket. Reinitialize
1255 * logging (since our pid has changed).
1256 * We break out of the loop to handle
1259 platform_post_fork_child();
1260 startup_pipe = startup_p[1];
1261 close_startup_pipes();
1262 close_listen_socks();
1263 *sock_in = *newsock;
1264 *sock_out = *newsock;
1265 log_init(__progname,
1267 options.log_facility,
1274 /* Parent. Stay in the loop. */
1275 platform_post_fork_parent(pid);
1277 error("fork: %.100s", strerror(errno));
1279 debug("Forked child %ld.", (long)pid);
1281 close(startup_p[1]);
1284 send_rexec_state(config_s[0], &cfg);
1290 * Mark that the key has been used (it
1291 * was "given" to the child).
1293 if ((options.protocol & SSH_PROTO_1) &&
1295 /* Schedule server key regeneration alarm. */
1296 signal(SIGALRM, key_regeneration_alarm);
1297 alarm(options.key_regeneration_time);
1304 * Ensure that our random state differs
1305 * from that of the child
1310 /* child process check (or debug mode) */
1311 if (num_listen_socks < 0)
1318 * Main program for the daemon.
1321 main(int ac, char **av)
1323 extern char *optarg;
1325 int opt, i, j, on = 1;
1326 int sock_in = -1, sock_out = -1, newsock = -1;
1327 const char *remote_ip;
1330 int config_s[2] = { -1 , -1 };
1331 u_int64_t ibytes, obytes;
1335 struct connection_info *connection_info = get_connection_info(0, 0);
1337 #ifdef HAVE_SECUREWARE
1338 (void)set_auth_parameters(ac, av);
1340 __progname = ssh_get_progname(av[0]);
1342 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1345 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1346 for (i = 0; i < ac; i++)
1347 saved_argv[i] = xstrdup(av[i]);
1348 saved_argv[i] = NULL;
1350 #ifndef HAVE_SETPROCTITLE
1351 /* Prepare for later setproctitle emulation */
1352 compat_init_setproctitle(ac, av);
1356 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1357 debug("setgroups(): %.200s", strerror(errno));
1359 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1362 /* Initialize configuration options to their default values. */
1363 initialize_server_options(&options);
1365 /* Parse command-line arguments. */
1366 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1369 options.address_family = AF_INET;
1372 options.address_family = AF_INET6;
1375 config_file_name = optarg;
1378 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1379 fprintf(stderr, "too many host certificates.\n");
1382 options.host_cert_files[options.num_host_cert_files++] =
1383 derelativise_path(optarg);
1386 if (debug_flag == 0) {
1388 options.log_level = SYSLOG_LEVEL_DEBUG1;
1389 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1390 options.log_level++;
1412 options.log_level = SYSLOG_LEVEL_QUIET;
1415 options.server_key_bits = (int)strtonum(optarg, 256,
1419 options.ports_from_cmdline = 1;
1420 if (options.num_ports >= MAX_PORTS) {
1421 fprintf(stderr, "too many ports.\n");
1424 options.ports[options.num_ports++] = a2port(optarg);
1425 if (options.ports[options.num_ports-1] <= 0) {
1426 fprintf(stderr, "Bad port number.\n");
1431 if ((options.login_grace_time = convtime(optarg)) == -1) {
1432 fprintf(stderr, "Invalid login grace time.\n");
1437 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1438 fprintf(stderr, "Invalid key regeneration interval.\n");
1443 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1444 fprintf(stderr, "too many host keys.\n");
1447 options.host_key_files[options.num_host_key_files++] =
1448 derelativise_path(optarg);
1457 if (parse_server_match_testspec(connection_info,
1462 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1463 if (utmp_len > MAXHOSTNAMELEN) {
1464 fprintf(stderr, "Invalid utmp length.\n");
1469 line = xstrdup(optarg);
1470 if (process_server_config_line(&options, line,
1471 "command-line", 0, NULL, NULL) != 0)
1481 if (rexeced_flag || inetd_flag)
1483 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1484 fatal("sshd re-exec requires execution with an absolute path");
1486 closefrom(REEXEC_MIN_FREE_FD);
1488 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1490 OpenSSL_add_all_algorithms();
1493 * Force logging to stderr until we have loaded the private host
1494 * key (unless started from inetd)
1496 log_init(__progname,
1497 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1498 SYSLOG_LEVEL_INFO : options.log_level,
1499 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1500 SYSLOG_FACILITY_AUTH : options.log_facility,
1501 log_stderr || !inetd_flag);
1504 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1505 * root's environment
1507 if (getenv("KRB5CCNAME") != NULL)
1508 (void) unsetenv("KRB5CCNAME");
1511 /* Cray can define user privs drop all privs now!
1512 * Not needed on PRIV_SU systems!
1517 sensitive_data.server_key = NULL;
1518 sensitive_data.ssh1_host_key = NULL;
1519 sensitive_data.have_ssh1_key = 0;
1520 sensitive_data.have_ssh2_key = 0;
1523 * If we're doing an extended config test, make sure we have all of
1524 * the parameters we need. If we're not doing an extended test,
1525 * do not silently ignore connection test params.
1527 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0)
1528 fatal("user, host and addr are all required when testing "
1530 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0)
1531 fatal("Config test connection parameter (-C) provided without "
1534 /* Fetch our configuration */
1537 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1539 load_server_config(config_file_name, &cfg);
1541 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1546 /* Fill in default values for those options not explicitly set. */
1547 fill_default_server_options(&options);
1549 /* challenge-response is implemented via keyboard interactive */
1550 if (options.challenge_response_authentication)
1551 options.kbd_interactive_authentication = 1;
1553 /* set default channel AF */
1554 channel_set_af(options.address_family);
1556 /* Check that there are no remaining arguments. */
1558 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1562 debug("sshd version %.100s", SSH_RELEASE);
1564 /* Store privilege separation user for later use if required. */
1565 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1566 if (use_privsep || options.kerberos_authentication)
1567 fatal("Privilege separation user %s does not exist",
1570 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1571 privsep_pw = pwcopy(privsep_pw);
1572 xfree(privsep_pw->pw_passwd);
1573 privsep_pw->pw_passwd = xstrdup("*");
1577 /* load private host keys */
1578 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1580 for (i = 0; i < options.num_host_key_files; i++)
1581 sensitive_data.host_keys[i] = NULL;
1583 for (i = 0; i < options.num_host_key_files; i++) {
1584 key = key_load_private(options.host_key_files[i], "", NULL);
1585 sensitive_data.host_keys[i] = key;
1587 error("Could not load host key: %s",
1588 options.host_key_files[i]);
1589 sensitive_data.host_keys[i] = NULL;
1592 switch (key->type) {
1594 sensitive_data.ssh1_host_key = key;
1595 sensitive_data.have_ssh1_key = 1;
1600 sensitive_data.have_ssh2_key = 1;
1603 debug("private host key: #%d type %d %s", i, key->type,
1606 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1607 logit("Disabling protocol version 1. Could not load host key");
1608 options.protocol &= ~SSH_PROTO_1;
1610 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1611 logit("Disabling protocol version 2. Could not load host key");
1612 options.protocol &= ~SSH_PROTO_2;
1614 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1615 logit("sshd: no hostkeys available -- exiting.");
1620 * Load certificates. They are stored in an array at identical
1621 * indices to the public keys that they relate to.
1623 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1625 for (i = 0; i < options.num_host_key_files; i++)
1626 sensitive_data.host_certificates[i] = NULL;
1628 for (i = 0; i < options.num_host_cert_files; i++) {
1629 key = key_load_public(options.host_cert_files[i], NULL);
1631 error("Could not load host certificate: %s",
1632 options.host_cert_files[i]);
1635 if (!key_is_cert(key)) {
1636 error("Certificate file is not a certificate: %s",
1637 options.host_cert_files[i]);
1641 /* Find matching private key */
1642 for (j = 0; j < options.num_host_key_files; j++) {
1643 if (key_equal_public(key,
1644 sensitive_data.host_keys[j])) {
1645 sensitive_data.host_certificates[j] = key;
1649 if (j >= options.num_host_key_files) {
1650 error("No matching private key for certificate: %s",
1651 options.host_cert_files[i]);
1655 sensitive_data.host_certificates[j] = key;
1656 debug("host certificate: #%d type %d %s", j, key->type,
1659 /* Check certain values for sanity. */
1660 if (options.protocol & SSH_PROTO_1) {
1661 if (options.server_key_bits < 512 ||
1662 options.server_key_bits > 32768) {
1663 fprintf(stderr, "Bad server key size.\n");
1667 * Check that server and host key lengths differ sufficiently. This
1668 * is necessary to make double encryption work with rsaref. Oh, I
1669 * hate software patents. I dont know if this can go? Niels
1671 if (options.server_key_bits >
1672 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1673 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1674 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1675 SSH_KEY_BITS_RESERVED) {
1676 options.server_key_bits =
1677 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1678 SSH_KEY_BITS_RESERVED;
1679 debug("Forcing server key to %d bits to make it differ from host key.",
1680 options.server_key_bits);
1687 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1688 (S_ISDIR(st.st_mode) == 0))
1689 fatal("Missing privilege separation directory: %s",
1690 _PATH_PRIVSEP_CHROOT_DIR);
1693 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1694 (st.st_uid != getuid () ||
1695 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1697 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1699 fatal("%s must be owned by root and not group or "
1700 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1703 if (test_flag > 1) {
1704 if (server_match_spec_complete(connection_info) == 1)
1705 parse_server_match_config(&options, connection_info);
1706 dump_config(&options);
1709 /* Configuration looks good, so exit if in test mode. */
1714 * Clear out any supplemental groups we may have inherited. This
1715 * prevents inadvertent creation of files with bad modes (in the
1716 * portable version at least, it's certainly possible for PAM
1717 * to create a file, and we can't control the code in every
1718 * module which might be used).
1720 if (setgroups(0, NULL) < 0)
1721 debug("setgroups() failed: %.200s", strerror(errno));
1724 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1725 for (i = 0; i < rexec_argc; i++) {
1726 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1727 rexec_argv[i] = saved_argv[i];
1729 rexec_argv[rexec_argc] = "-R";
1730 rexec_argv[rexec_argc + 1] = NULL;
1733 /* Ensure that umask disallows at least group and world write */
1734 new_umask = umask(0077) | 0022;
1735 (void) umask(new_umask);
1737 /* Initialize the log (it is reinitialized below in case we forked). */
1738 if (debug_flag && (!inetd_flag || rexeced_flag))
1740 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1743 * If not in debugging mode, and not started from inetd, disconnect
1744 * from the controlling terminal, and fork. The original process
1747 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1750 #endif /* TIOCNOTTY */
1751 if (daemon(0, 0) < 0)
1752 fatal("daemon() failed: %.200s", strerror(errno));
1754 /* Disconnect from the controlling tty. */
1756 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1758 (void) ioctl(fd, TIOCNOTTY, NULL);
1761 #endif /* TIOCNOTTY */
1763 /* Reinitialize the log (because of the fork above). */
1764 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1766 /* Initialize the random number generator. */
1769 /* Chdir to the root directory so that the current disk can be
1770 unmounted if desired. */
1773 /* ignore SIGPIPE */
1774 signal(SIGPIPE, SIG_IGN);
1776 /* Get a connection, either from inetd or a listening TCP socket */
1778 server_accept_inetd(&sock_in, &sock_out);
1780 platform_pre_listen();
1783 if (options.protocol & SSH_PROTO_1)
1784 generate_ephemeral_server_key();
1786 signal(SIGHUP, sighup_handler);
1787 signal(SIGCHLD, main_sigchld_handler);
1788 signal(SIGTERM, sigterm_handler);
1789 signal(SIGQUIT, sigterm_handler);
1792 * Write out the pid file after the sigterm handler
1793 * is setup and the listen sockets are bound
1796 FILE *f = fopen(options.pid_file, "w");
1799 error("Couldn't create pid file \"%s\": %s",
1800 options.pid_file, strerror(errno));
1802 fprintf(f, "%ld\n", (long) getpid());
1807 /* Accept a connection and return in a forked child */
1808 server_accept_loop(&sock_in, &sock_out,
1809 &newsock, config_s);
1812 /* This is the child processing a new connection. */
1813 setproctitle("%s", "[accepted]");
1816 * Create a new session and process group since the 4.4BSD
1817 * setlogin() affects the entire process group. We don't
1818 * want the child to be able to affect the parent.
1820 #if !defined(SSHD_ACQUIRES_CTTY)
1822 * If setsid is called, on some platforms sshd will later acquire a
1823 * controlling terminal which will result in "could not set
1824 * controlling tty" errors.
1826 if (!debug_flag && !inetd_flag && setsid() < 0)
1827 error("setsid: %.100s", strerror(errno));
1833 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1834 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1835 dup2(newsock, STDIN_FILENO);
1836 dup2(STDIN_FILENO, STDOUT_FILENO);
1837 if (startup_pipe == -1)
1838 close(REEXEC_STARTUP_PIPE_FD);
1840 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1842 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1844 if (startup_pipe != -1)
1845 close(startup_pipe);
1847 execv(rexec_argv[0], rexec_argv);
1849 /* Reexec has failed, fall back and continue */
1850 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1851 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1852 log_init(__progname, options.log_level,
1853 options.log_facility, log_stderr);
1856 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1858 close(REEXEC_CONFIG_PASS_FD);
1859 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1860 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1861 dup2(fd, STDIN_FILENO);
1862 dup2(fd, STDOUT_FILENO);
1863 if (fd > STDERR_FILENO)
1866 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1867 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1870 /* Executed child processes don't need these. */
1871 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1872 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1875 * Disable the key regeneration alarm. We will not regenerate the
1876 * key since we are no longer in a position to give it to anyone. We
1877 * will not restart on SIGHUP since it no longer makes sense.
1880 signal(SIGALRM, SIG_DFL);
1881 signal(SIGHUP, SIG_DFL);
1882 signal(SIGTERM, SIG_DFL);
1883 signal(SIGQUIT, SIG_DFL);
1884 signal(SIGCHLD, SIG_DFL);
1885 signal(SIGINT, SIG_DFL);
1888 * Register our connection. This turns encryption off because we do
1891 packet_set_connection(sock_in, sock_out);
1892 packet_set_server();
1894 /* Set SO_KEEPALIVE if requested. */
1895 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1896 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1897 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1899 if ((remote_port = get_remote_port()) < 0) {
1900 debug("get_remote_port failed");
1905 * We use get_canonical_hostname with usedns = 0 instead of
1906 * get_remote_ipaddr here so IP options will be checked.
1908 (void) get_canonical_hostname(0);
1910 * The rest of the code depends on the fact that
1911 * get_remote_ipaddr() caches the remote ip, even if
1912 * the socket goes away.
1914 remote_ip = get_remote_ipaddr();
1916 #ifdef SSH_AUDIT_EVENTS
1917 audit_connection_from(remote_ip, remote_port);
1920 allow_severity = options.log_facility|LOG_INFO;
1921 deny_severity = options.log_facility|LOG_WARNING;
1922 /* Check whether logins are denied from this host. */
1923 if (packet_connection_is_on_socket()) {
1924 struct request_info req;
1926 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1929 if (!hosts_access(&req)) {
1930 debug("Connection refused by tcp wrapper");
1933 fatal("libwrap refuse returns");
1936 #endif /* LIBWRAP */
1938 /* Log the connection. */
1939 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1942 * We don't want to listen forever unless the other side
1943 * successfully authenticates itself. So we set up an alarm which is
1944 * cleared after successful authentication. A limit of zero
1945 * indicates no limit. Note that we don't set the alarm in debugging
1946 * mode; it is just annoying to have the server exit just when you
1947 * are about to discover the bug.
1949 signal(SIGALRM, grace_alarm_handler);
1951 alarm(options.login_grace_time);
1953 sshd_exchange_identification(sock_in, sock_out);
1955 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1956 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1957 generate_ephemeral_server_key();
1959 packet_set_nonblocking();
1961 /* allocate authentication context */
1962 authctxt = xcalloc(1, sizeof(*authctxt));
1964 authctxt->loginmsg = &loginmsg;
1966 /* XXX global for cleanup, access from other modules */
1967 the_authctxt = authctxt;
1969 /* prepare buffer to collect messages to display to user after login */
1970 buffer_init(&loginmsg);
1974 if (privsep_preauth(authctxt) == 1)
1977 /* perform the key exchange */
1978 /* authenticate user and start session */
1981 do_authentication2(authctxt);
1984 do_authentication(authctxt);
1987 * If we use privilege separation, the unprivileged child transfers
1988 * the current keystate and exits
1991 mm_send_keystate(pmonitor);
1997 * Cancel the alarm we set to limit the time taken for
2001 signal(SIGALRM, SIG_DFL);
2002 authctxt->authenticated = 1;
2003 if (startup_pipe != -1) {
2004 close(startup_pipe);
2008 #ifdef SSH_AUDIT_EVENTS
2009 audit_event(SSH_AUTH_SUCCESS);
2013 if (options.gss_authentication) {
2014 temporarily_use_uid(authctxt->pw);
2015 ssh_gssapi_storecreds();
2020 if (options.use_pam) {
2027 * In privilege separation, we fork another child and prepare
2028 * file descriptor passing.
2031 privsep_postauth(authctxt);
2032 /* the monitor process [priv] will not return */
2034 destroy_sensitive_data();
2037 packet_set_timeout(options.client_alive_interval,
2038 options.client_alive_count_max);
2040 /* Start session. */
2041 do_authenticated(authctxt);
2043 /* The connection has been terminated. */
2044 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2045 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2046 verbose("Transferred: sent %llu, received %llu bytes",
2047 (unsigned long long)obytes, (unsigned long long)ibytes);
2049 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2052 if (options.use_pam)
2054 #endif /* USE_PAM */
2056 #ifdef SSH_AUDIT_EVENTS
2057 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2069 * Decrypt session_key_int using our private server key and private host key
2070 * (key with larger modulus first).
2073 ssh1_session_key(BIGNUM *session_key_int)
2077 if (BN_cmp(sensitive_data.server_key->rsa->n,
2078 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2079 /* Server key has bigger modulus. */
2080 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2081 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2082 SSH_KEY_BITS_RESERVED) {
2083 fatal("do_connection: %s: "
2084 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2085 get_remote_ipaddr(),
2086 BN_num_bits(sensitive_data.server_key->rsa->n),
2087 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2088 SSH_KEY_BITS_RESERVED);
2090 if (rsa_private_decrypt(session_key_int, session_key_int,
2091 sensitive_data.server_key->rsa) <= 0)
2093 if (rsa_private_decrypt(session_key_int, session_key_int,
2094 sensitive_data.ssh1_host_key->rsa) <= 0)
2097 /* Host key has bigger modulus (or they are equal). */
2098 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2099 BN_num_bits(sensitive_data.server_key->rsa->n) +
2100 SSH_KEY_BITS_RESERVED) {
2101 fatal("do_connection: %s: "
2102 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2103 get_remote_ipaddr(),
2104 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2105 BN_num_bits(sensitive_data.server_key->rsa->n),
2106 SSH_KEY_BITS_RESERVED);
2108 if (rsa_private_decrypt(session_key_int, session_key_int,
2109 sensitive_data.ssh1_host_key->rsa) < 0)
2111 if (rsa_private_decrypt(session_key_int, session_key_int,
2112 sensitive_data.server_key->rsa) < 0)
2125 BIGNUM *session_key_int;
2126 u_char session_key[SSH_SESSION_KEY_LENGTH];
2128 u_int cipher_type, auth_mask, protocol_flags;
2131 * Generate check bytes that the client must send back in the user
2132 * packet in order for it to be accepted; this is used to defy ip
2133 * spoofing attacks. Note that this only works against somebody
2134 * doing IP spoofing from a remote machine; any machine on the local
2135 * network can still see outgoing packets and catch the random
2136 * cookie. This only affects rhosts authentication, and this is one
2137 * of the reasons why it is inherently insecure.
2139 arc4random_buf(cookie, sizeof(cookie));
2142 * Send our public key. We include in the packet 64 bits of random
2143 * data that must be matched in the reply in order to prevent IP
2146 packet_start(SSH_SMSG_PUBLIC_KEY);
2147 for (i = 0; i < 8; i++)
2148 packet_put_char(cookie[i]);
2150 /* Store our public server RSA key. */
2151 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2152 packet_put_bignum(sensitive_data.server_key->rsa->e);
2153 packet_put_bignum(sensitive_data.server_key->rsa->n);
2155 /* Store our public host RSA key. */
2156 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2157 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2158 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2160 /* Put protocol flags. */
2161 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2163 /* Declare which ciphers we support. */
2164 packet_put_int(cipher_mask_ssh1(0));
2166 /* Declare supported authentication types. */
2168 if (options.rhosts_rsa_authentication)
2169 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2170 if (options.rsa_authentication)
2171 auth_mask |= 1 << SSH_AUTH_RSA;
2172 if (options.challenge_response_authentication == 1)
2173 auth_mask |= 1 << SSH_AUTH_TIS;
2174 if (options.password_authentication)
2175 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2176 packet_put_int(auth_mask);
2178 /* Send the packet and wait for it to be sent. */
2180 packet_write_wait();
2182 debug("Sent %d bit server key and %d bit host key.",
2183 BN_num_bits(sensitive_data.server_key->rsa->n),
2184 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2186 /* Read clients reply (cipher type and session key). */
2187 packet_read_expect(SSH_CMSG_SESSION_KEY);
2189 /* Get cipher type and check whether we accept this. */
2190 cipher_type = packet_get_char();
2192 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2193 packet_disconnect("Warning: client selects unsupported cipher.");
2195 /* Get check bytes from the packet. These must match those we
2196 sent earlier with the public key packet. */
2197 for (i = 0; i < 8; i++)
2198 if (cookie[i] != packet_get_char())
2199 packet_disconnect("IP Spoofing check bytes do not match.");
2201 debug("Encryption type: %.200s", cipher_name(cipher_type));
2203 /* Get the encrypted integer. */
2204 if ((session_key_int = BN_new()) == NULL)
2205 fatal("do_ssh1_kex: BN_new failed");
2206 packet_get_bignum(session_key_int);
2208 protocol_flags = packet_get_int();
2209 packet_set_protocol_flags(protocol_flags);
2212 /* Decrypt session_key_int using host/server keys */
2213 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2216 * Extract session key from the decrypted integer. The key is in the
2217 * least significant 256 bits of the integer; the first byte of the
2218 * key is in the highest bits.
2221 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2222 len = BN_num_bytes(session_key_int);
2223 if (len < 0 || (u_int)len > sizeof(session_key)) {
2224 error("do_ssh1_kex: bad session key len from %s: "
2225 "session_key_int %d > sizeof(session_key) %lu",
2226 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2229 memset(session_key, 0, sizeof(session_key));
2230 BN_bn2bin(session_key_int,
2231 session_key + sizeof(session_key) - len);
2233 derive_ssh1_session_id(
2234 sensitive_data.ssh1_host_key->rsa->n,
2235 sensitive_data.server_key->rsa->n,
2236 cookie, session_id);
2238 * Xor the first 16 bytes of the session key with the
2241 for (i = 0; i < 16; i++)
2242 session_key[i] ^= session_id[i];
2246 int bytes = BN_num_bytes(session_key_int);
2247 u_char *buf = xmalloc(bytes);
2250 logit("do_connection: generating a fake encryption key");
2251 BN_bn2bin(session_key_int, buf);
2253 MD5_Update(&md, buf, bytes);
2254 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2255 MD5_Final(session_key, &md);
2257 MD5_Update(&md, session_key, 16);
2258 MD5_Update(&md, buf, bytes);
2259 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2260 MD5_Final(session_key + 16, &md);
2261 memset(buf, 0, bytes);
2263 for (i = 0; i < 16; i++)
2264 session_id[i] = session_key[i] ^ session_key[i + 16];
2266 /* Destroy the private and public keys. No longer. */
2267 destroy_sensitive_data();
2270 mm_ssh1_session_id(session_id);
2272 /* Destroy the decrypted integer. It is no longer needed. */
2273 BN_clear_free(session_key_int);
2275 /* Set the session key. From this on all communications will be encrypted. */
2276 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2278 /* Destroy our copy of the session key. It is no longer needed. */
2279 memset(session_key, 0, sizeof(session_key));
2281 debug("Received session key; encryption turned on.");
2283 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2284 packet_start(SSH_SMSG_SUCCESS);
2286 packet_write_wait();
2290 * SSH2 key exchange: diffie-hellman-group1-sha1
2297 if (options.ciphers != NULL) {
2298 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2299 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2301 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2302 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2303 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2304 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2306 if (options.macs != NULL) {
2307 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2308 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2310 if (options.compression == COMP_NONE) {
2311 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2312 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2313 } else if (options.compression == COMP_DELAYED) {
2314 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2315 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2317 if (options.kex_algorithms != NULL)
2318 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
2320 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2322 /* start key exchange */
2323 kex = kex_setup(myproposal);
2324 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2325 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2326 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2327 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2328 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2330 kex->client_version_string=client_version_string;
2331 kex->server_version_string=server_version_string;
2332 kex->load_host_public_key=&get_hostkey_public_by_type;
2333 kex->load_host_private_key=&get_hostkey_private_by_type;
2334 kex->host_key_index=&get_hostkey_index;
2338 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2340 session_id2 = kex->session_id;
2341 session_id2_len = kex->session_id_len;
2344 /* send 1st encrypted/maced/compressed message */
2345 packet_start(SSH2_MSG_IGNORE);
2346 packet_put_cstring("markus");
2348 packet_write_wait();
2353 /* server specific fatal cleanup */
2358 do_cleanup(the_authctxt);
2359 if (use_privsep && privsep_is_preauth && pmonitor->m_pid > 1) {
2360 debug("Killing privsep child %d", pmonitor->m_pid);
2361 if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2363 error("%s: kill(%d): %s", __func__,
2364 pmonitor->m_pid, strerror(errno));
2367 #ifdef SSH_AUDIT_EVENTS
2368 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2369 if (!use_privsep || mm_is_monitor())
2370 audit_event(SSH_CONNECTION_ABANDON);