1 /* $OpenBSD: sshd.c,v 1.385 2011/06/23 09:34:13 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;
243 /* global authentication context */
244 Authctxt *the_authctxt = NULL;
246 /* sshd_config buffer */
249 /* message to be displayed after login */
252 /* Unprivileged user */
253 struct passwd *privsep_pw = NULL;
255 /* Prototypes for various functions defined later in this file. */
256 void destroy_sensitive_data(void);
257 void demote_sensitive_data(void);
259 static void do_ssh1_kex(void);
260 static void do_ssh2_kex(void);
263 * Close all listening sockets
266 close_listen_socks(void)
270 for (i = 0; i < num_listen_socks; i++)
271 close(listen_socks[i]);
272 num_listen_socks = -1;
276 close_startup_pipes(void)
281 for (i = 0; i < options.max_startups; i++)
282 if (startup_pipes[i] != -1)
283 close(startup_pipes[i]);
287 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
288 * the effect is to reread the configuration file (and to regenerate
294 sighup_handler(int sig)
296 int save_errno = errno;
299 signal(SIGHUP, sighup_handler);
304 * Called from the main program after receiving SIGHUP.
305 * Restarts the server.
310 logit("Received SIGHUP; restarting.");
311 close_listen_socks();
312 close_startup_pipes();
313 alarm(0); /* alarm timer persists across exec */
314 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
315 execv(saved_argv[0], saved_argv);
316 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
322 * Generic signal handler for terminating signals in the master daemon.
326 sigterm_handler(int sig)
328 received_sigterm = sig;
332 * SIGCHLD handler. This is called whenever a child dies. This will then
333 * reap any zombies left by exited children.
337 main_sigchld_handler(int sig)
339 int save_errno = errno;
343 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
344 (pid < 0 && errno == EINTR))
347 signal(SIGCHLD, main_sigchld_handler);
352 * Signal handler for the alarm after the login grace period has expired.
356 grace_alarm_handler(int sig)
358 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
359 kill(pmonitor->m_pid, SIGALRM);
361 /* Log error and exit. */
362 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
366 * Signal handler for the key regeneration alarm. Note that this
367 * alarm only occurs in the daemon waiting for connections, and it does not
368 * do anything with the private key or random state before forking.
369 * Thus there should be no concurrency control/asynchronous execution
373 generate_ephemeral_server_key(void)
375 verbose("Generating %s%d bit RSA key.",
376 sensitive_data.server_key ? "new " : "", options.server_key_bits);
377 if (sensitive_data.server_key != NULL)
378 key_free(sensitive_data.server_key);
379 sensitive_data.server_key = key_generate(KEY_RSA1,
380 options.server_key_bits);
381 verbose("RSA key generation complete.");
383 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
389 key_regeneration_alarm(int sig)
391 int save_errno = errno;
393 signal(SIGALRM, SIG_DFL);
399 sshd_exchange_identification(int sock_in, int sock_out)
403 int remote_major, remote_minor;
405 char *s, *newline = "\n";
406 char buf[256]; /* Must not be larger than remote_version. */
407 char remote_version[256]; /* Must be at least as big as buf. */
409 if ((options.protocol & SSH_PROTO_1) &&
410 (options.protocol & SSH_PROTO_2)) {
411 major = PROTOCOL_MAJOR_1;
413 } else if (options.protocol & SSH_PROTO_2) {
414 major = PROTOCOL_MAJOR_2;
415 minor = PROTOCOL_MINOR_2;
418 major = PROTOCOL_MAJOR_1;
419 minor = PROTOCOL_MINOR_1;
421 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
422 SSH_VERSION, newline);
423 server_version_string = xstrdup(buf);
425 /* Send our protocol version identification. */
426 if (roaming_atomicio(vwrite, sock_out, server_version_string,
427 strlen(server_version_string))
428 != strlen(server_version_string)) {
429 logit("Could not write ident string to %s", get_remote_ipaddr());
433 /* Read other sides version identification. */
434 memset(buf, 0, sizeof(buf));
435 for (i = 0; i < sizeof(buf) - 1; i++) {
436 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
437 logit("Did not receive identification string from %s",
438 get_remote_ipaddr());
441 if (buf[i] == '\r') {
443 /* Kludge for F-Secure Macintosh < 1.0.2 */
445 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
449 if (buf[i] == '\n') {
454 buf[sizeof(buf) - 1] = 0;
455 client_version_string = xstrdup(buf);
458 * Check that the versions match. In future this might accept
459 * several versions and set appropriate flags to handle them.
461 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
462 &remote_major, &remote_minor, remote_version) != 3) {
463 s = "Protocol mismatch.\n";
464 (void) atomicio(vwrite, sock_out, s, strlen(s));
467 logit("Bad protocol version identification '%.100s' from %s",
468 client_version_string, get_remote_ipaddr());
471 debug("Client protocol version %d.%d; client software version %.100s",
472 remote_major, remote_minor, remote_version);
474 compat_datafellows(remote_version);
476 if (datafellows & SSH_BUG_PROBE) {
477 logit("probed from %s with %s. Don't panic.",
478 get_remote_ipaddr(), client_version_string);
482 if (datafellows & SSH_BUG_SCANNER) {
483 logit("scanned from %s with %s. Don't panic.",
484 get_remote_ipaddr(), client_version_string);
489 switch (remote_major) {
491 if (remote_minor == 99) {
492 if (options.protocol & SSH_PROTO_2)
498 if (!(options.protocol & SSH_PROTO_1)) {
502 if (remote_minor < 3) {
503 packet_disconnect("Your ssh version is too old and "
504 "is no longer supported. Please install a newer version.");
505 } else if (remote_minor == 3) {
506 /* note that this disables agent-forwarding */
511 if (options.protocol & SSH_PROTO_2) {
520 chop(server_version_string);
521 debug("Local version string %.200s", server_version_string);
524 s = "Protocol major versions differ.\n";
525 (void) atomicio(vwrite, sock_out, s, strlen(s));
528 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
530 server_version_string, client_version_string);
535 /* Destroy the host and server keys. They will no longer be needed. */
537 destroy_sensitive_data(void)
541 if (sensitive_data.server_key) {
542 key_free(sensitive_data.server_key);
543 sensitive_data.server_key = NULL;
545 for (i = 0; i < options.num_host_key_files; i++) {
546 if (sensitive_data.host_keys[i]) {
547 key_free(sensitive_data.host_keys[i]);
548 sensitive_data.host_keys[i] = NULL;
550 if (sensitive_data.host_certificates[i]) {
551 key_free(sensitive_data.host_certificates[i]);
552 sensitive_data.host_certificates[i] = NULL;
555 sensitive_data.ssh1_host_key = NULL;
556 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
559 /* Demote private to public keys for network child */
561 demote_sensitive_data(void)
566 if (sensitive_data.server_key) {
567 tmp = key_demote(sensitive_data.server_key);
568 key_free(sensitive_data.server_key);
569 sensitive_data.server_key = tmp;
572 for (i = 0; i < options.num_host_key_files; i++) {
573 if (sensitive_data.host_keys[i]) {
574 tmp = key_demote(sensitive_data.host_keys[i]);
575 key_free(sensitive_data.host_keys[i]);
576 sensitive_data.host_keys[i] = tmp;
577 if (tmp->type == KEY_RSA1)
578 sensitive_data.ssh1_host_key = tmp;
580 /* Certs do not need demotion */
583 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
587 privsep_preauth_child(void)
592 /* Enable challenge-response authentication for privilege separation */
593 privsep_challenge_enable();
596 arc4random_buf(rnd, sizeof(rnd));
597 RAND_seed(rnd, sizeof(rnd));
599 /* Demote the private keys to public keys. */
600 demote_sensitive_data();
602 /* Change our root directory */
603 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
604 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
606 if (chdir("/") == -1)
607 fatal("chdir(\"/\"): %s", strerror(errno));
609 /* Drop our privileges */
610 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
611 (u_int)privsep_pw->pw_gid);
613 /* XXX not ready, too heavy after chroot */
614 do_setusercontext(privsep_pw);
616 gidset[0] = privsep_pw->pw_gid;
617 if (setgroups(1, gidset) < 0)
618 fatal("setgroups: %.100s", strerror(errno));
619 permanently_set_uid(privsep_pw);
624 privsep_preauth(Authctxt *authctxt)
628 struct ssh_sandbox *box = NULL;
630 /* Set up unprivileged child process to deal with network data */
631 pmonitor = monitor_init();
632 /* Store a pointer to the kex for later rekeying */
633 pmonitor->m_pkex = &xxx_kex;
635 if (use_privsep == PRIVSEP_SANDBOX)
636 box = ssh_sandbox_init();
639 fatal("fork of unprivileged child failed");
640 } else if (pid != 0) {
641 debug2("Network child is on pid %ld", (long)pid);
644 ssh_sandbox_parent_preauth(box, pid);
645 pmonitor->m_pid = pid;
646 monitor_child_preauth(authctxt, pmonitor);
649 monitor_sync(pmonitor);
651 /* Wait for the child's exit status */
652 while (waitpid(pid, &status, 0) < 0) {
654 fatal("%s: waitpid: %s", __func__,
657 if (WIFEXITED(status)) {
658 if (WEXITSTATUS(status) != 0)
659 fatal("%s: preauth child exited with status %d",
660 __func__, WEXITSTATUS(status));
661 } else if (WIFSIGNALED(status))
662 fatal("%s: preauth child terminated by signal %d",
663 __func__, WTERMSIG(status));
665 ssh_sandbox_parent_finish(box);
669 close(pmonitor->m_sendfd);
670 close(pmonitor->m_log_recvfd);
672 /* Arrange for logging to be sent to the monitor */
673 set_log_handler(mm_log_handler, pmonitor);
675 /* Demote the child */
676 if (getuid() == 0 || geteuid() == 0)
677 privsep_preauth_child();
678 setproctitle("%s", "[net]");
680 ssh_sandbox_child(box);
687 privsep_postauth(Authctxt *authctxt)
691 #ifdef DISABLE_FD_PASSING
694 if (authctxt->pw->pw_uid == 0 || options.use_login) {
696 /* File descriptor passing is broken or root login */
701 /* New socket pair */
702 monitor_reinit(pmonitor);
704 pmonitor->m_pid = fork();
705 if (pmonitor->m_pid == -1)
706 fatal("fork of unprivileged child failed");
707 else if (pmonitor->m_pid != 0) {
708 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
709 buffer_clear(&loginmsg);
710 monitor_child_postauth(pmonitor);
718 close(pmonitor->m_sendfd);
719 pmonitor->m_sendfd = -1;
721 /* Demote the private keys to public keys. */
722 demote_sensitive_data();
725 arc4random_buf(rnd, sizeof(rnd));
726 RAND_seed(rnd, sizeof(rnd));
728 /* Drop privileges */
729 do_setusercontext(authctxt->pw);
732 /* It is safe now to apply the key state */
733 monitor_apply_keystate(pmonitor);
736 * Tell the packet layer that authentication was successful, since
737 * this information is not part of the key state.
739 packet_set_authenticated();
743 list_hostkey_types(void)
752 for (i = 0; i < options.num_host_key_files; i++) {
753 key = sensitive_data.host_keys[i];
760 if (buffer_len(&b) > 0)
761 buffer_append(&b, ",", 1);
762 p = key_ssh_name(key);
763 buffer_append(&b, p, strlen(p));
766 /* If the private key has a cert peer, then list that too */
767 key = sensitive_data.host_certificates[i];
771 case KEY_RSA_CERT_V00:
772 case KEY_DSA_CERT_V00:
776 if (buffer_len(&b) > 0)
777 buffer_append(&b, ",", 1);
778 p = key_ssh_name(key);
779 buffer_append(&b, p, strlen(p));
783 buffer_append(&b, "\0", 1);
784 ret = xstrdup(buffer_ptr(&b));
786 debug("list_hostkey_types: %s", ret);
791 get_hostkey_by_type(int type, int need_private)
796 for (i = 0; i < options.num_host_key_files; i++) {
798 case KEY_RSA_CERT_V00:
799 case KEY_DSA_CERT_V00:
803 key = sensitive_data.host_certificates[i];
806 key = sensitive_data.host_keys[i];
809 if (key != NULL && key->type == type)
810 return need_private ?
811 sensitive_data.host_keys[i] : key;
817 get_hostkey_public_by_type(int type)
819 return get_hostkey_by_type(type, 0);
823 get_hostkey_private_by_type(int type)
825 return get_hostkey_by_type(type, 1);
829 get_hostkey_by_index(int ind)
831 if (ind < 0 || ind >= options.num_host_key_files)
833 return (sensitive_data.host_keys[ind]);
837 get_hostkey_index(Key *key)
841 for (i = 0; i < options.num_host_key_files; i++) {
842 if (key_is_cert(key)) {
843 if (key == sensitive_data.host_certificates[i])
846 if (key == sensitive_data.host_keys[i])
854 * returns 1 if connection should be dropped, 0 otherwise.
855 * dropping starts at connection #max_startups_begin with a probability
856 * of (max_startups_rate/100). the probability increases linearly until
857 * all connections are dropped for startups > max_startups
860 drop_connection(int startups)
864 if (startups < options.max_startups_begin)
866 if (startups >= options.max_startups)
868 if (options.max_startups_rate == 100)
871 p = 100 - options.max_startups_rate;
872 p *= startups - options.max_startups_begin;
873 p /= options.max_startups - options.max_startups_begin;
874 p += options.max_startups_rate;
875 r = arc4random_uniform(100);
877 debug("drop_connection: p %d, r %d", p, r);
878 return (r < p) ? 1 : 0;
884 fprintf(stderr, "%s, %s\n",
885 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
887 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
888 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
889 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
895 send_rexec_state(int fd, Buffer *conf)
899 debug3("%s: entering fd = %d config len %d", __func__, fd,
903 * Protocol from reexec master to child:
904 * string configuration
905 * u_int ephemeral_key_follows
906 * bignum e (only if ephemeral_key_follows == 1)
912 * string rngseed (only if OpenSSL is not self-seeded)
915 buffer_put_cstring(&m, buffer_ptr(conf));
917 if (sensitive_data.server_key != NULL &&
918 sensitive_data.server_key->type == KEY_RSA1) {
919 buffer_put_int(&m, 1);
920 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
921 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
922 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
923 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
924 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
925 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
927 buffer_put_int(&m, 0);
929 #ifndef OPENSSL_PRNG_ONLY
930 rexec_send_rng_seed(&m);
933 if (ssh_msg_send(fd, 0, &m) == -1)
934 fatal("%s: ssh_msg_send failed", __func__);
938 debug3("%s: done", __func__);
942 recv_rexec_state(int fd, Buffer *conf)
948 debug3("%s: entering fd = %d", __func__, fd);
952 if (ssh_msg_recv(fd, &m) == -1)
953 fatal("%s: ssh_msg_recv failed", __func__);
954 if (buffer_get_char(&m) != 0)
955 fatal("%s: rexec version mismatch", __func__);
957 cp = buffer_get_string(&m, &len);
959 buffer_append(conf, cp, len + 1);
962 if (buffer_get_int(&m)) {
963 if (sensitive_data.server_key != NULL)
964 key_free(sensitive_data.server_key);
965 sensitive_data.server_key = key_new_private(KEY_RSA1);
966 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
967 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
968 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
969 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
970 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
971 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
972 rsa_generate_additional_parameters(
973 sensitive_data.server_key->rsa);
976 #ifndef OPENSSL_PRNG_ONLY
977 rexec_recv_rng_seed(&m);
982 debug3("%s: done", __func__);
985 /* Accept a connection from inetd */
987 server_accept_inetd(int *sock_in, int *sock_out)
993 close(REEXEC_CONFIG_PASS_FD);
994 *sock_in = *sock_out = dup(STDIN_FILENO);
996 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
997 close(REEXEC_STARTUP_PIPE_FD);
1000 *sock_in = dup(STDIN_FILENO);
1001 *sock_out = dup(STDOUT_FILENO);
1004 * We intentionally do not close the descriptors 0, 1, and 2
1005 * as our code for setting the descriptors won't work if
1006 * ttyfd happens to be one of those.
1008 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1009 dup2(fd, STDIN_FILENO);
1010 dup2(fd, STDOUT_FILENO);
1011 if (fd > STDOUT_FILENO)
1014 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1018 * Listen for TCP connections
1023 int ret, listen_sock, on = 1;
1024 struct addrinfo *ai;
1025 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1027 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1028 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1030 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1031 fatal("Too many listen sockets. "
1032 "Enlarge MAX_LISTEN_SOCKS");
1033 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1034 ntop, sizeof(ntop), strport, sizeof(strport),
1035 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1036 error("getnameinfo failed: %.100s",
1037 ssh_gai_strerror(ret));
1040 /* Create socket for listening. */
1041 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1043 if (listen_sock < 0) {
1044 /* kernel may not support ipv6 */
1045 verbose("socket: %.100s", strerror(errno));
1048 if (set_nonblock(listen_sock) == -1) {
1053 * Set socket options.
1054 * Allow local port reuse in TIME_WAIT.
1056 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1057 &on, sizeof(on)) == -1)
1058 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1060 /* Only communicate in IPv6 over AF_INET6 sockets. */
1061 if (ai->ai_family == AF_INET6)
1062 sock_set_v6only(listen_sock);
1064 debug("Bind to port %s on %s.", strport, ntop);
1066 /* Bind the socket to the desired port. */
1067 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1068 error("Bind to port %s on %s failed: %.200s.",
1069 strport, ntop, strerror(errno));
1073 listen_socks[num_listen_socks] = listen_sock;
1076 /* Start listening on the port. */
1077 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1078 fatal("listen on [%s]:%s: %.100s",
1079 ntop, strport, strerror(errno));
1080 logit("Server listening on %s port %s.", ntop, strport);
1082 freeaddrinfo(options.listen_addrs);
1084 if (!num_listen_socks)
1085 fatal("Cannot bind any address.");
1089 * The main TCP accept loop. Note that, for the non-debug case, returns
1090 * from this function are in a forked subprocess.
1093 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1096 int i, j, ret, maxfd;
1097 int key_used = 0, startups = 0;
1098 int startup_p[2] = { -1 , -1 };
1099 struct sockaddr_storage from;
1103 /* setup fd set for accept */
1106 for (i = 0; i < num_listen_socks; i++)
1107 if (listen_socks[i] > maxfd)
1108 maxfd = listen_socks[i];
1109 /* pipes connected to unauthenticated childs */
1110 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1111 for (i = 0; i < options.max_startups; i++)
1112 startup_pipes[i] = -1;
1115 * Stay listening for connections until the system crashes or
1116 * the daemon is killed with a signal.
1119 if (received_sighup)
1123 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1126 for (i = 0; i < num_listen_socks; i++)
1127 FD_SET(listen_socks[i], fdset);
1128 for (i = 0; i < options.max_startups; i++)
1129 if (startup_pipes[i] != -1)
1130 FD_SET(startup_pipes[i], fdset);
1132 /* Wait in select until there is a connection. */
1133 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1134 if (ret < 0 && errno != EINTR)
1135 error("select: %.100s", strerror(errno));
1136 if (received_sigterm) {
1137 logit("Received signal %d; terminating.",
1138 (int) received_sigterm);
1139 close_listen_socks();
1140 unlink(options.pid_file);
1141 exit(received_sigterm == SIGTERM ? 0 : 255);
1143 if (key_used && key_do_regen) {
1144 generate_ephemeral_server_key();
1151 for (i = 0; i < options.max_startups; i++)
1152 if (startup_pipes[i] != -1 &&
1153 FD_ISSET(startup_pipes[i], fdset)) {
1155 * the read end of the pipe is ready
1156 * if the child has closed the pipe
1157 * after successful authentication
1158 * or if the child has died
1160 close(startup_pipes[i]);
1161 startup_pipes[i] = -1;
1164 for (i = 0; i < num_listen_socks; i++) {
1165 if (!FD_ISSET(listen_socks[i], fdset))
1167 fromlen = sizeof(from);
1168 *newsock = accept(listen_socks[i],
1169 (struct sockaddr *)&from, &fromlen);
1171 if (errno != EINTR && errno != EAGAIN &&
1172 errno != EWOULDBLOCK)
1173 error("accept: %.100s", strerror(errno));
1176 if (unset_nonblock(*newsock) == -1) {
1180 if (drop_connection(startups) == 1) {
1181 debug("drop connection #%d", startups);
1185 if (pipe(startup_p) == -1) {
1190 if (rexec_flag && socketpair(AF_UNIX,
1191 SOCK_STREAM, 0, config_s) == -1) {
1192 error("reexec socketpair: %s",
1195 close(startup_p[0]);
1196 close(startup_p[1]);
1200 for (j = 0; j < options.max_startups; j++)
1201 if (startup_pipes[j] == -1) {
1202 startup_pipes[j] = startup_p[0];
1203 if (maxfd < startup_p[0])
1204 maxfd = startup_p[0];
1210 * Got connection. Fork a child to handle it, unless
1211 * we are in debugging mode.
1215 * In debugging mode. Close the listening
1216 * socket, and start processing the
1217 * connection without forking.
1219 debug("Server will not fork when running in debugging mode.");
1220 close_listen_socks();
1221 *sock_in = *newsock;
1222 *sock_out = *newsock;
1223 close(startup_p[0]);
1224 close(startup_p[1]);
1228 send_rexec_state(config_s[0],
1236 * Normal production daemon. Fork, and have
1237 * the child process the connection. The
1238 * parent continues listening.
1240 platform_pre_fork();
1241 if ((pid = fork()) == 0) {
1243 * Child. Close the listening and
1244 * max_startup sockets. Start using
1245 * the accepted socket. Reinitialize
1246 * logging (since our pid has changed).
1247 * We break out of the loop to handle
1250 platform_post_fork_child();
1251 startup_pipe = startup_p[1];
1252 close_startup_pipes();
1253 close_listen_socks();
1254 *sock_in = *newsock;
1255 *sock_out = *newsock;
1256 log_init(__progname,
1258 options.log_facility,
1265 /* Parent. Stay in the loop. */
1266 platform_post_fork_parent(pid);
1268 error("fork: %.100s", strerror(errno));
1270 debug("Forked child %ld.", (long)pid);
1272 close(startup_p[1]);
1275 send_rexec_state(config_s[0], &cfg);
1281 * Mark that the key has been used (it
1282 * was "given" to the child).
1284 if ((options.protocol & SSH_PROTO_1) &&
1286 /* Schedule server key regeneration alarm. */
1287 signal(SIGALRM, key_regeneration_alarm);
1288 alarm(options.key_regeneration_time);
1295 * Ensure that our random state differs
1296 * from that of the child
1301 /* child process check (or debug mode) */
1302 if (num_listen_socks < 0)
1309 * Main program for the daemon.
1312 main(int ac, char **av)
1314 extern char *optarg;
1316 int opt, i, j, on = 1;
1317 int sock_in = -1, sock_out = -1, newsock = -1;
1318 const char *remote_ip;
1319 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1321 char *line, *p, *cp;
1322 int config_s[2] = { -1 , -1 };
1323 u_int64_t ibytes, obytes;
1328 #ifdef HAVE_SECUREWARE
1329 (void)set_auth_parameters(ac, av);
1331 __progname = ssh_get_progname(av[0]);
1333 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1336 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1337 for (i = 0; i < ac; i++)
1338 saved_argv[i] = xstrdup(av[i]);
1339 saved_argv[i] = NULL;
1341 #ifndef HAVE_SETPROCTITLE
1342 /* Prepare for later setproctitle emulation */
1343 compat_init_setproctitle(ac, av);
1347 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1348 debug("setgroups(): %.200s", strerror(errno));
1350 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1353 /* Initialize configuration options to their default values. */
1354 initialize_server_options(&options);
1356 /* Parse command-line arguments. */
1357 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1360 options.address_family = AF_INET;
1363 options.address_family = AF_INET6;
1366 config_file_name = optarg;
1369 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1370 fprintf(stderr, "too many host certificates.\n");
1373 options.host_cert_files[options.num_host_cert_files++] =
1374 derelativise_path(optarg);
1377 if (debug_flag == 0) {
1379 options.log_level = SYSLOG_LEVEL_DEBUG1;
1380 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1381 options.log_level++;
1403 options.log_level = SYSLOG_LEVEL_QUIET;
1406 options.server_key_bits = (int)strtonum(optarg, 256,
1410 options.ports_from_cmdline = 1;
1411 if (options.num_ports >= MAX_PORTS) {
1412 fprintf(stderr, "too many ports.\n");
1415 options.ports[options.num_ports++] = a2port(optarg);
1416 if (options.ports[options.num_ports-1] <= 0) {
1417 fprintf(stderr, "Bad port number.\n");
1422 if ((options.login_grace_time = convtime(optarg)) == -1) {
1423 fprintf(stderr, "Invalid login grace time.\n");
1428 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1429 fprintf(stderr, "Invalid key regeneration interval.\n");
1434 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1435 fprintf(stderr, "too many host keys.\n");
1438 options.host_key_files[options.num_host_key_files++] =
1439 derelativise_path(optarg);
1449 while ((p = strsep(&cp, ",")) && *p != '\0') {
1450 if (strncmp(p, "addr=", 5) == 0)
1451 test_addr = xstrdup(p + 5);
1452 else if (strncmp(p, "host=", 5) == 0)
1453 test_host = xstrdup(p + 5);
1454 else if (strncmp(p, "user=", 5) == 0)
1455 test_user = xstrdup(p + 5);
1457 fprintf(stderr, "Invalid test "
1458 "mode specification %s\n", p);
1464 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1465 if (utmp_len > MAXHOSTNAMELEN) {
1466 fprintf(stderr, "Invalid utmp length.\n");
1471 line = xstrdup(optarg);
1472 if (process_server_config_line(&options, line,
1473 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1483 if (rexeced_flag || inetd_flag)
1485 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1486 fatal("sshd re-exec requires execution with an absolute path");
1488 closefrom(REEXEC_MIN_FREE_FD);
1490 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1492 OpenSSL_add_all_algorithms();
1495 * Force logging to stderr until we have loaded the private host
1496 * key (unless started from inetd)
1498 log_init(__progname,
1499 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1500 SYSLOG_LEVEL_INFO : options.log_level,
1501 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1502 SYSLOG_FACILITY_AUTH : options.log_facility,
1503 log_stderr || !inetd_flag);
1506 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1507 * root's environment
1509 if (getenv("KRB5CCNAME") != NULL)
1510 unsetenv("KRB5CCNAME");
1513 /* Cray can define user privs drop all privs now!
1514 * Not needed on PRIV_SU systems!
1519 sensitive_data.server_key = NULL;
1520 sensitive_data.ssh1_host_key = NULL;
1521 sensitive_data.have_ssh1_key = 0;
1522 sensitive_data.have_ssh2_key = 0;
1525 * If we're doing an extended config test, make sure we have all of
1526 * the parameters we need. If we're not doing an extended test,
1527 * do not silently ignore connection test params.
1529 if (test_flag >= 2 &&
1530 (test_user != NULL || test_host != NULL || test_addr != NULL)
1531 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1532 fatal("user, host and addr are all required when testing "
1534 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1536 fatal("Config test connection parameter (-C) provided without "
1539 /* Fetch our configuration */
1542 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1544 load_server_config(config_file_name, &cfg);
1546 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1547 &cfg, NULL, NULL, NULL);
1551 /* Fill in default values for those options not explicitly set. */
1552 fill_default_server_options(&options);
1554 /* challenge-response is implemented via keyboard interactive */
1555 if (options.challenge_response_authentication)
1556 options.kbd_interactive_authentication = 1;
1558 /* set default channel AF */
1559 channel_set_af(options.address_family);
1561 /* Check that there are no remaining arguments. */
1563 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1567 debug("sshd version %.100s", SSH_RELEASE);
1569 /* Store privilege separation user for later use if required. */
1570 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1571 if (use_privsep || options.kerberos_authentication)
1572 fatal("Privilege separation user %s does not exist",
1575 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1576 privsep_pw = pwcopy(privsep_pw);
1577 xfree(privsep_pw->pw_passwd);
1578 privsep_pw->pw_passwd = xstrdup("*");
1582 /* load private host keys */
1583 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1585 for (i = 0; i < options.num_host_key_files; i++)
1586 sensitive_data.host_keys[i] = NULL;
1588 for (i = 0; i < options.num_host_key_files; i++) {
1589 key = key_load_private(options.host_key_files[i], "", NULL);
1590 sensitive_data.host_keys[i] = key;
1592 error("Could not load host key: %s",
1593 options.host_key_files[i]);
1594 sensitive_data.host_keys[i] = NULL;
1597 switch (key->type) {
1599 sensitive_data.ssh1_host_key = key;
1600 sensitive_data.have_ssh1_key = 1;
1605 sensitive_data.have_ssh2_key = 1;
1608 debug("private host key: #%d type %d %s", i, key->type,
1611 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1612 logit("Disabling protocol version 1. Could not load host key");
1613 options.protocol &= ~SSH_PROTO_1;
1615 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1616 logit("Disabling protocol version 2. Could not load host key");
1617 options.protocol &= ~SSH_PROTO_2;
1619 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1620 logit("sshd: no hostkeys available -- exiting.");
1625 * Load certificates. They are stored in an array at identical
1626 * indices to the public keys that they relate to.
1628 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1630 for (i = 0; i < options.num_host_key_files; i++)
1631 sensitive_data.host_certificates[i] = NULL;
1633 for (i = 0; i < options.num_host_cert_files; i++) {
1634 key = key_load_public(options.host_cert_files[i], NULL);
1636 error("Could not load host certificate: %s",
1637 options.host_cert_files[i]);
1640 if (!key_is_cert(key)) {
1641 error("Certificate file is not a certificate: %s",
1642 options.host_cert_files[i]);
1646 /* Find matching private key */
1647 for (j = 0; j < options.num_host_key_files; j++) {
1648 if (key_equal_public(key,
1649 sensitive_data.host_keys[j])) {
1650 sensitive_data.host_certificates[j] = key;
1654 if (j >= options.num_host_key_files) {
1655 error("No matching private key for certificate: %s",
1656 options.host_cert_files[i]);
1660 sensitive_data.host_certificates[j] = key;
1661 debug("host certificate: #%d type %d %s", j, key->type,
1664 /* Check certain values for sanity. */
1665 if (options.protocol & SSH_PROTO_1) {
1666 if (options.server_key_bits < 512 ||
1667 options.server_key_bits > 32768) {
1668 fprintf(stderr, "Bad server key size.\n");
1672 * Check that server and host key lengths differ sufficiently. This
1673 * is necessary to make double encryption work with rsaref. Oh, I
1674 * hate software patents. I dont know if this can go? Niels
1676 if (options.server_key_bits >
1677 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1678 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1679 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1680 SSH_KEY_BITS_RESERVED) {
1681 options.server_key_bits =
1682 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1683 SSH_KEY_BITS_RESERVED;
1684 debug("Forcing server key to %d bits to make it differ from host key.",
1685 options.server_key_bits);
1692 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1693 (S_ISDIR(st.st_mode) == 0))
1694 fatal("Missing privilege separation directory: %s",
1695 _PATH_PRIVSEP_CHROOT_DIR);
1698 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1699 (st.st_uid != getuid () ||
1700 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1702 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1704 fatal("%s must be owned by root and not group or "
1705 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1708 if (test_flag > 1) {
1709 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1710 parse_server_match_config(&options, test_user,
1711 test_host, test_addr);
1712 dump_config(&options);
1715 /* Configuration looks good, so exit if in test mode. */
1720 * Clear out any supplemental groups we may have inherited. This
1721 * prevents inadvertent creation of files with bad modes (in the
1722 * portable version at least, it's certainly possible for PAM
1723 * to create a file, and we can't control the code in every
1724 * module which might be used).
1726 if (setgroups(0, NULL) < 0)
1727 debug("setgroups() failed: %.200s", strerror(errno));
1730 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1731 for (i = 0; i < rexec_argc; i++) {
1732 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1733 rexec_argv[i] = saved_argv[i];
1735 rexec_argv[rexec_argc] = "-R";
1736 rexec_argv[rexec_argc + 1] = NULL;
1739 /* Ensure that umask disallows at least group and world write */
1740 new_umask = umask(0077) | 0022;
1741 (void) umask(new_umask);
1743 /* Initialize the log (it is reinitialized below in case we forked). */
1744 if (debug_flag && (!inetd_flag || rexeced_flag))
1746 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1749 * If not in debugging mode, and not started from inetd, disconnect
1750 * from the controlling terminal, and fork. The original process
1753 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1756 #endif /* TIOCNOTTY */
1757 if (daemon(0, 0) < 0)
1758 fatal("daemon() failed: %.200s", strerror(errno));
1760 /* Disconnect from the controlling tty. */
1762 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1764 (void) ioctl(fd, TIOCNOTTY, NULL);
1767 #endif /* TIOCNOTTY */
1769 /* Reinitialize the log (because of the fork above). */
1770 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1772 /* Initialize the random number generator. */
1775 /* Chdir to the root directory so that the current disk can be
1776 unmounted if desired. */
1779 /* ignore SIGPIPE */
1780 signal(SIGPIPE, SIG_IGN);
1782 /* Get a connection, either from inetd or a listening TCP socket */
1784 server_accept_inetd(&sock_in, &sock_out);
1786 platform_pre_listen();
1789 if (options.protocol & SSH_PROTO_1)
1790 generate_ephemeral_server_key();
1792 signal(SIGHUP, sighup_handler);
1793 signal(SIGCHLD, main_sigchld_handler);
1794 signal(SIGTERM, sigterm_handler);
1795 signal(SIGQUIT, sigterm_handler);
1798 * Write out the pid file after the sigterm handler
1799 * is setup and the listen sockets are bound
1802 FILE *f = fopen(options.pid_file, "w");
1805 error("Couldn't create pid file \"%s\": %s",
1806 options.pid_file, strerror(errno));
1808 fprintf(f, "%ld\n", (long) getpid());
1813 /* Accept a connection and return in a forked child */
1814 server_accept_loop(&sock_in, &sock_out,
1815 &newsock, config_s);
1818 /* This is the child processing a new connection. */
1819 setproctitle("%s", "[accepted]");
1822 * Create a new session and process group since the 4.4BSD
1823 * setlogin() affects the entire process group. We don't
1824 * want the child to be able to affect the parent.
1826 #if !defined(SSHD_ACQUIRES_CTTY)
1828 * If setsid is called, on some platforms sshd will later acquire a
1829 * controlling terminal which will result in "could not set
1830 * controlling tty" errors.
1832 if (!debug_flag && !inetd_flag && setsid() < 0)
1833 error("setsid: %.100s", strerror(errno));
1839 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1840 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1841 dup2(newsock, STDIN_FILENO);
1842 dup2(STDIN_FILENO, STDOUT_FILENO);
1843 if (startup_pipe == -1)
1844 close(REEXEC_STARTUP_PIPE_FD);
1846 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1848 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1850 if (startup_pipe != -1)
1851 close(startup_pipe);
1853 execv(rexec_argv[0], rexec_argv);
1855 /* Reexec has failed, fall back and continue */
1856 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1857 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1858 log_init(__progname, options.log_level,
1859 options.log_facility, log_stderr);
1862 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1864 close(REEXEC_CONFIG_PASS_FD);
1865 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1866 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1867 dup2(fd, STDIN_FILENO);
1868 dup2(fd, STDOUT_FILENO);
1869 if (fd > STDERR_FILENO)
1872 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1873 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1876 /* Executed child processes don't need these. */
1877 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1878 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1881 * Disable the key regeneration alarm. We will not regenerate the
1882 * key since we are no longer in a position to give it to anyone. We
1883 * will not restart on SIGHUP since it no longer makes sense.
1886 signal(SIGALRM, SIG_DFL);
1887 signal(SIGHUP, SIG_DFL);
1888 signal(SIGTERM, SIG_DFL);
1889 signal(SIGQUIT, SIG_DFL);
1890 signal(SIGCHLD, SIG_DFL);
1891 signal(SIGINT, SIG_DFL);
1894 * Register our connection. This turns encryption off because we do
1897 packet_set_connection(sock_in, sock_out);
1898 packet_set_server();
1900 /* Set SO_KEEPALIVE if requested. */
1901 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1902 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1903 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1905 if ((remote_port = get_remote_port()) < 0) {
1906 debug("get_remote_port failed");
1911 * We use get_canonical_hostname with usedns = 0 instead of
1912 * get_remote_ipaddr here so IP options will be checked.
1914 (void) get_canonical_hostname(0);
1916 * The rest of the code depends on the fact that
1917 * get_remote_ipaddr() caches the remote ip, even if
1918 * the socket goes away.
1920 remote_ip = get_remote_ipaddr();
1922 #ifdef SSH_AUDIT_EVENTS
1923 audit_connection_from(remote_ip, remote_port);
1926 allow_severity = options.log_facility|LOG_INFO;
1927 deny_severity = options.log_facility|LOG_WARNING;
1928 /* Check whether logins are denied from this host. */
1929 if (packet_connection_is_on_socket()) {
1930 struct request_info req;
1932 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1935 if (!hosts_access(&req)) {
1936 debug("Connection refused by tcp wrapper");
1939 fatal("libwrap refuse returns");
1942 #endif /* LIBWRAP */
1944 /* Log the connection. */
1945 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1948 * We don't want to listen forever unless the other side
1949 * successfully authenticates itself. So we set up an alarm which is
1950 * cleared after successful authentication. A limit of zero
1951 * indicates no limit. Note that we don't set the alarm in debugging
1952 * mode; it is just annoying to have the server exit just when you
1953 * are about to discover the bug.
1955 signal(SIGALRM, grace_alarm_handler);
1957 alarm(options.login_grace_time);
1959 sshd_exchange_identification(sock_in, sock_out);
1961 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1962 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1963 generate_ephemeral_server_key();
1965 packet_set_nonblocking();
1967 /* allocate authentication context */
1968 authctxt = xcalloc(1, sizeof(*authctxt));
1970 authctxt->loginmsg = &loginmsg;
1972 /* XXX global for cleanup, access from other modules */
1973 the_authctxt = authctxt;
1975 /* prepare buffer to collect messages to display to user after login */
1976 buffer_init(&loginmsg);
1980 if (privsep_preauth(authctxt) == 1)
1983 /* perform the key exchange */
1984 /* authenticate user and start session */
1987 do_authentication2(authctxt);
1990 do_authentication(authctxt);
1993 * If we use privilege separation, the unprivileged child transfers
1994 * the current keystate and exits
1997 mm_send_keystate(pmonitor);
2003 * Cancel the alarm we set to limit the time taken for
2007 signal(SIGALRM, SIG_DFL);
2008 authctxt->authenticated = 1;
2009 if (startup_pipe != -1) {
2010 close(startup_pipe);
2014 #ifdef SSH_AUDIT_EVENTS
2015 audit_event(SSH_AUTH_SUCCESS);
2019 if (options.gss_authentication) {
2020 temporarily_use_uid(authctxt->pw);
2021 ssh_gssapi_storecreds();
2026 if (options.use_pam) {
2033 * In privilege separation, we fork another child and prepare
2034 * file descriptor passing.
2037 privsep_postauth(authctxt);
2038 /* the monitor process [priv] will not return */
2040 destroy_sensitive_data();
2043 packet_set_timeout(options.client_alive_interval,
2044 options.client_alive_count_max);
2046 /* Start session. */
2047 do_authenticated(authctxt);
2049 /* The connection has been terminated. */
2050 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2051 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2052 verbose("Transferred: sent %llu, received %llu bytes",
2053 (unsigned long long)obytes, (unsigned long long)ibytes);
2055 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2058 if (options.use_pam)
2060 #endif /* USE_PAM */
2062 #ifdef SSH_AUDIT_EVENTS
2063 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2075 * Decrypt session_key_int using our private server key and private host key
2076 * (key with larger modulus first).
2079 ssh1_session_key(BIGNUM *session_key_int)
2083 if (BN_cmp(sensitive_data.server_key->rsa->n,
2084 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2085 /* Server key has bigger modulus. */
2086 if (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) {
2089 fatal("do_connection: %s: "
2090 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2091 get_remote_ipaddr(),
2092 BN_num_bits(sensitive_data.server_key->rsa->n),
2093 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2094 SSH_KEY_BITS_RESERVED);
2096 if (rsa_private_decrypt(session_key_int, session_key_int,
2097 sensitive_data.server_key->rsa) <= 0)
2099 if (rsa_private_decrypt(session_key_int, session_key_int,
2100 sensitive_data.ssh1_host_key->rsa) <= 0)
2103 /* Host key has bigger modulus (or they are equal). */
2104 if (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) {
2107 fatal("do_connection: %s: "
2108 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2109 get_remote_ipaddr(),
2110 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2111 BN_num_bits(sensitive_data.server_key->rsa->n),
2112 SSH_KEY_BITS_RESERVED);
2114 if (rsa_private_decrypt(session_key_int, session_key_int,
2115 sensitive_data.ssh1_host_key->rsa) < 0)
2117 if (rsa_private_decrypt(session_key_int, session_key_int,
2118 sensitive_data.server_key->rsa) < 0)
2131 BIGNUM *session_key_int;
2132 u_char session_key[SSH_SESSION_KEY_LENGTH];
2134 u_int cipher_type, auth_mask, protocol_flags;
2137 * Generate check bytes that the client must send back in the user
2138 * packet in order for it to be accepted; this is used to defy ip
2139 * spoofing attacks. Note that this only works against somebody
2140 * doing IP spoofing from a remote machine; any machine on the local
2141 * network can still see outgoing packets and catch the random
2142 * cookie. This only affects rhosts authentication, and this is one
2143 * of the reasons why it is inherently insecure.
2145 arc4random_buf(cookie, sizeof(cookie));
2148 * Send our public key. We include in the packet 64 bits of random
2149 * data that must be matched in the reply in order to prevent IP
2152 packet_start(SSH_SMSG_PUBLIC_KEY);
2153 for (i = 0; i < 8; i++)
2154 packet_put_char(cookie[i]);
2156 /* Store our public server RSA key. */
2157 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2158 packet_put_bignum(sensitive_data.server_key->rsa->e);
2159 packet_put_bignum(sensitive_data.server_key->rsa->n);
2161 /* Store our public host RSA key. */
2162 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2163 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2164 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2166 /* Put protocol flags. */
2167 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2169 /* Declare which ciphers we support. */
2170 packet_put_int(cipher_mask_ssh1(0));
2172 /* Declare supported authentication types. */
2174 if (options.rhosts_rsa_authentication)
2175 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2176 if (options.rsa_authentication)
2177 auth_mask |= 1 << SSH_AUTH_RSA;
2178 if (options.challenge_response_authentication == 1)
2179 auth_mask |= 1 << SSH_AUTH_TIS;
2180 if (options.password_authentication)
2181 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2182 packet_put_int(auth_mask);
2184 /* Send the packet and wait for it to be sent. */
2186 packet_write_wait();
2188 debug("Sent %d bit server key and %d bit host key.",
2189 BN_num_bits(sensitive_data.server_key->rsa->n),
2190 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2192 /* Read clients reply (cipher type and session key). */
2193 packet_read_expect(SSH_CMSG_SESSION_KEY);
2195 /* Get cipher type and check whether we accept this. */
2196 cipher_type = packet_get_char();
2198 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2199 packet_disconnect("Warning: client selects unsupported cipher.");
2201 /* Get check bytes from the packet. These must match those we
2202 sent earlier with the public key packet. */
2203 for (i = 0; i < 8; i++)
2204 if (cookie[i] != packet_get_char())
2205 packet_disconnect("IP Spoofing check bytes do not match.");
2207 debug("Encryption type: %.200s", cipher_name(cipher_type));
2209 /* Get the encrypted integer. */
2210 if ((session_key_int = BN_new()) == NULL)
2211 fatal("do_ssh1_kex: BN_new failed");
2212 packet_get_bignum(session_key_int);
2214 protocol_flags = packet_get_int();
2215 packet_set_protocol_flags(protocol_flags);
2218 /* Decrypt session_key_int using host/server keys */
2219 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2222 * Extract session key from the decrypted integer. The key is in the
2223 * least significant 256 bits of the integer; the first byte of the
2224 * key is in the highest bits.
2227 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2228 len = BN_num_bytes(session_key_int);
2229 if (len < 0 || (u_int)len > sizeof(session_key)) {
2230 error("do_ssh1_kex: bad session key len from %s: "
2231 "session_key_int %d > sizeof(session_key) %lu",
2232 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2235 memset(session_key, 0, sizeof(session_key));
2236 BN_bn2bin(session_key_int,
2237 session_key + sizeof(session_key) - len);
2239 derive_ssh1_session_id(
2240 sensitive_data.ssh1_host_key->rsa->n,
2241 sensitive_data.server_key->rsa->n,
2242 cookie, session_id);
2244 * Xor the first 16 bytes of the session key with the
2247 for (i = 0; i < 16; i++)
2248 session_key[i] ^= session_id[i];
2252 int bytes = BN_num_bytes(session_key_int);
2253 u_char *buf = xmalloc(bytes);
2256 logit("do_connection: generating a fake encryption key");
2257 BN_bn2bin(session_key_int, buf);
2259 MD5_Update(&md, buf, bytes);
2260 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2261 MD5_Final(session_key, &md);
2263 MD5_Update(&md, session_key, 16);
2264 MD5_Update(&md, buf, bytes);
2265 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2266 MD5_Final(session_key + 16, &md);
2267 memset(buf, 0, bytes);
2269 for (i = 0; i < 16; i++)
2270 session_id[i] = session_key[i] ^ session_key[i + 16];
2272 /* Destroy the private and public keys. No longer. */
2273 destroy_sensitive_data();
2276 mm_ssh1_session_id(session_id);
2278 /* Destroy the decrypted integer. It is no longer needed. */
2279 BN_clear_free(session_key_int);
2281 /* Set the session key. From this on all communications will be encrypted. */
2282 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2284 /* Destroy our copy of the session key. It is no longer needed. */
2285 memset(session_key, 0, sizeof(session_key));
2287 debug("Received session key; encryption turned on.");
2289 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2290 packet_start(SSH_SMSG_SUCCESS);
2292 packet_write_wait();
2296 * SSH2 key exchange: diffie-hellman-group1-sha1
2303 if (options.ciphers != NULL) {
2304 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2305 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2307 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2308 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2309 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2310 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2312 if (options.macs != NULL) {
2313 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2314 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2316 if (options.compression == COMP_NONE) {
2317 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2318 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2319 } else if (options.compression == COMP_DELAYED) {
2320 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2321 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2323 if (options.kex_algorithms != NULL)
2324 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
2326 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2328 /* start key exchange */
2329 kex = kex_setup(myproposal);
2330 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2331 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2332 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2333 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2334 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2336 kex->client_version_string=client_version_string;
2337 kex->server_version_string=server_version_string;
2338 kex->load_host_public_key=&get_hostkey_public_by_type;
2339 kex->load_host_private_key=&get_hostkey_private_by_type;
2340 kex->host_key_index=&get_hostkey_index;
2344 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2346 session_id2 = kex->session_id;
2347 session_id2_len = kex->session_id_len;
2350 /* send 1st encrypted/maced/compressed message */
2351 packet_start(SSH2_MSG_IGNORE);
2352 packet_put_cstring("markus");
2354 packet_write_wait();
2359 /* server specific fatal cleanup */
2364 do_cleanup(the_authctxt);
2365 #ifdef SSH_AUDIT_EVENTS
2366 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2367 if (!use_privsep || mm_is_monitor())
2368 audit_event(SSH_CONNECTION_ABANDON);