1 /* $OpenBSD: sshd.c,v 1.367 2009/05/28 16:50:16 andreas 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"
123 #ifdef USE_SECURITY_SESSION_API
124 #include <Security/AuthSession.h>
139 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
140 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
141 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
142 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
144 extern char *__progname;
146 /* Server configuration options. */
147 ServerOptions options;
149 /* Name of the server configuration file. */
150 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
153 * Debug mode flag. This can be set on the command line. If debug
154 * mode is enabled, extra debugging output will be sent to the system
155 * log, the daemon will not go to background, and will exit after processing
156 * the first connection.
160 /* Flag indicating that the daemon should only test the configuration and keys. */
163 /* Flag indicating that the daemon is being started from inetd. */
166 /* Flag indicating that sshd should not detach and become a daemon. */
167 int no_daemon_flag = 0;
169 /* debug goes to stderr unless inetd_flag is set */
172 /* Saved arguments to main(). */
177 int rexeced_flag = 0;
183 * The sockets that the server is listening; this is used in the SIGHUP
186 #define MAX_LISTEN_SOCKS 16
187 int listen_socks[MAX_LISTEN_SOCKS];
188 int num_listen_socks = 0;
191 * the client's version string, passed by sshd2 in compat mode. if != NULL,
192 * sshd will skip the version-number exchange
194 char *client_version_string = NULL;
195 char *server_version_string = NULL;
197 /* for rekeying XXX fixme */
201 * Any really sensitive data in the application is contained in this
202 * structure. The idea is that this structure could be locked into memory so
203 * that the pages do not get written into swap. However, there are some
204 * problems. The private key contains BIGNUMs, and we do not (in principle)
205 * have access to the internals of them, and locking just the structure is
206 * not very useful. Currently, memory locking is not implemented.
209 Key *server_key; /* ephemeral server key */
210 Key *ssh1_host_key; /* ssh1 host key */
211 Key **host_keys; /* all private host keys */
214 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
218 * Flag indicating whether the RSA server key needs to be regenerated.
219 * Is set in the SIGALRM handler and cleared when the key is regenerated.
221 static volatile sig_atomic_t key_do_regen = 0;
223 /* This is set to true when a signal is received. */
224 static volatile sig_atomic_t received_sighup = 0;
225 static volatile sig_atomic_t received_sigterm = 0;
227 /* session identifier, used by RSA-auth */
228 u_char session_id[16];
231 u_char *session_id2 = NULL;
232 u_int session_id2_len = 0;
234 /* record remote hostname or ip */
235 u_int utmp_len = MAXHOSTNAMELEN;
237 /* options.max_startup sized array of fd ints */
238 int *startup_pipes = NULL;
239 int startup_pipe; /* in child */
241 /* variables used for privilege separation */
242 int use_privsep = -1;
243 struct monitor *pmonitor = NULL;
245 /* global authentication context */
246 Authctxt *the_authctxt = NULL;
248 /* sshd_config buffer */
251 /* message to be displayed after login */
254 /* Unprivileged user */
255 struct passwd *privsep_pw = NULL;
258 /* Linux out-of-memory killer adjustment */
259 static char oom_adj_save[8];
262 /* Prototypes for various functions defined later in this file. */
263 void destroy_sensitive_data(void);
264 void demote_sensitive_data(void);
266 static void do_ssh1_kex(void);
267 static void do_ssh2_kex(void);
270 * Close all listening sockets
273 close_listen_socks(void)
277 for (i = 0; i < num_listen_socks; i++)
278 close(listen_socks[i]);
279 num_listen_socks = -1;
283 close_startup_pipes(void)
288 for (i = 0; i < options.max_startups; i++)
289 if (startup_pipes[i] != -1)
290 close(startup_pipes[i]);
294 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
295 * the effect is to reread the configuration file (and to regenerate
301 sighup_handler(int sig)
303 int save_errno = errno;
306 signal(SIGHUP, sighup_handler);
311 * Called from the main program after receiving SIGHUP.
312 * Restarts the server.
317 logit("Received SIGHUP; restarting.");
318 close_listen_socks();
319 close_startup_pipes();
320 alarm(0); /* alarm timer persists across exec */
321 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
322 execv(saved_argv[0], saved_argv);
323 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
329 * Generic signal handler for terminating signals in the master daemon.
333 sigterm_handler(int sig)
335 received_sigterm = sig;
339 * SIGCHLD handler. This is called whenever a child dies. This will then
340 * reap any zombies left by exited children.
344 main_sigchld_handler(int sig)
346 int save_errno = errno;
350 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
351 (pid < 0 && errno == EINTR))
354 signal(SIGCHLD, main_sigchld_handler);
359 * Signal handler for the alarm after the login grace period has expired.
363 grace_alarm_handler(int sig)
365 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
366 kill(pmonitor->m_pid, SIGALRM);
368 /* Log error and exit. */
369 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
373 * Signal handler for the key regeneration alarm. Note that this
374 * alarm only occurs in the daemon waiting for connections, and it does not
375 * do anything with the private key or random state before forking.
376 * Thus there should be no concurrency control/asynchronous execution
380 generate_ephemeral_server_key(void)
382 verbose("Generating %s%d bit RSA key.",
383 sensitive_data.server_key ? "new " : "", options.server_key_bits);
384 if (sensitive_data.server_key != NULL)
385 key_free(sensitive_data.server_key);
386 sensitive_data.server_key = key_generate(KEY_RSA1,
387 options.server_key_bits);
388 verbose("RSA key generation complete.");
390 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
396 key_regeneration_alarm(int sig)
398 int save_errno = errno;
400 signal(SIGALRM, SIG_DFL);
406 sshd_exchange_identification(int sock_in, int sock_out)
410 int remote_major, remote_minor;
412 char *s, *newline = "\n";
413 char buf[256]; /* Must not be larger than remote_version. */
414 char remote_version[256]; /* Must be at least as big as buf. */
416 if ((options.protocol & SSH_PROTO_1) &&
417 (options.protocol & SSH_PROTO_2)) {
418 major = PROTOCOL_MAJOR_1;
420 } else if (options.protocol & SSH_PROTO_2) {
421 major = PROTOCOL_MAJOR_2;
422 minor = PROTOCOL_MINOR_2;
425 major = PROTOCOL_MAJOR_1;
426 minor = PROTOCOL_MINOR_1;
428 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
429 options.debian_banner ? SSH_RELEASE : SSH_RELEASE_MINIMUM,
431 server_version_string = xstrdup(buf);
433 /* Send our protocol version identification. */
434 if (roaming_atomicio(vwrite, sock_out, server_version_string,
435 strlen(server_version_string))
436 != strlen(server_version_string)) {
437 logit("Could not write ident string to %s", get_remote_ipaddr());
441 /* Read other sides version identification. */
442 memset(buf, 0, sizeof(buf));
443 for (i = 0; i < sizeof(buf) - 1; i++) {
444 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
445 logit("Did not receive identification string from %s",
446 get_remote_ipaddr());
449 if (buf[i] == '\r') {
451 /* Kludge for F-Secure Macintosh < 1.0.2 */
453 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
457 if (buf[i] == '\n') {
462 buf[sizeof(buf) - 1] = 0;
463 client_version_string = xstrdup(buf);
466 * Check that the versions match. In future this might accept
467 * several versions and set appropriate flags to handle them.
469 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
470 &remote_major, &remote_minor, remote_version) != 3) {
471 s = "Protocol mismatch.\n";
472 (void) atomicio(vwrite, sock_out, s, strlen(s));
475 logit("Bad protocol version identification '%.100s' from %s",
476 client_version_string, get_remote_ipaddr());
479 debug("Client protocol version %d.%d; client software version %.100s",
480 remote_major, remote_minor, remote_version);
482 compat_datafellows(remote_version);
484 if (datafellows & SSH_BUG_PROBE) {
485 logit("probed from %s with %s. Don't panic.",
486 get_remote_ipaddr(), client_version_string);
490 if (datafellows & SSH_BUG_SCANNER) {
491 logit("scanned from %s with %s. Don't panic.",
492 get_remote_ipaddr(), client_version_string);
497 switch (remote_major) {
499 if (remote_minor == 99) {
500 if (options.protocol & SSH_PROTO_2)
506 if (!(options.protocol & SSH_PROTO_1)) {
510 if (remote_minor < 3) {
511 packet_disconnect("Your ssh version is too old and "
512 "is no longer supported. Please install a newer version.");
513 } else if (remote_minor == 3) {
514 /* note that this disables agent-forwarding */
519 if (options.protocol & SSH_PROTO_2) {
528 chop(server_version_string);
529 debug("Local version string %.200s", server_version_string);
532 s = "Protocol major versions differ.\n";
533 (void) atomicio(vwrite, sock_out, s, strlen(s));
536 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
538 server_version_string, client_version_string);
543 /* Destroy the host and server keys. They will no longer be needed. */
545 destroy_sensitive_data(void)
549 if (sensitive_data.server_key) {
550 key_free(sensitive_data.server_key);
551 sensitive_data.server_key = NULL;
553 for (i = 0; i < options.num_host_key_files; i++) {
554 if (sensitive_data.host_keys[i]) {
555 key_free(sensitive_data.host_keys[i]);
556 sensitive_data.host_keys[i] = NULL;
559 sensitive_data.ssh1_host_key = NULL;
560 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
563 /* Demote private to public keys for network child */
565 demote_sensitive_data(void)
570 if (sensitive_data.server_key) {
571 tmp = key_demote(sensitive_data.server_key);
572 key_free(sensitive_data.server_key);
573 sensitive_data.server_key = tmp;
576 for (i = 0; i < options.num_host_key_files; i++) {
577 if (sensitive_data.host_keys[i]) {
578 tmp = key_demote(sensitive_data.host_keys[i]);
579 key_free(sensitive_data.host_keys[i]);
580 sensitive_data.host_keys[i] = tmp;
581 if (tmp->type == KEY_RSA1)
582 sensitive_data.ssh1_host_key = tmp;
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)
632 /* Set up unprivileged child process to deal with network data */
633 pmonitor = monitor_init();
634 /* Store a pointer to the kex for later rekeying */
635 pmonitor->m_pkex = &xxx_kex;
639 fatal("fork of unprivileged child failed");
640 } else if (pid != 0) {
641 debug2("Network child is on pid %ld", (long)pid);
643 close(pmonitor->m_recvfd);
644 pmonitor->m_pid = pid;
645 monitor_child_preauth(authctxt, pmonitor);
646 close(pmonitor->m_sendfd);
649 monitor_sync(pmonitor);
651 /* Wait for the child's exit status */
652 while (waitpid(pid, &status, 0) < 0)
659 close(pmonitor->m_sendfd);
661 /* Demote the child */
662 if (getuid() == 0 || geteuid() == 0)
663 privsep_preauth_child();
664 setproctitle("%s", "[net]");
670 privsep_postauth(Authctxt *authctxt)
674 #ifdef DISABLE_FD_PASSING
677 if (authctxt->pw->pw_uid == 0 || options.use_login) {
679 /* File descriptor passing is broken or root login */
684 /* New socket pair */
685 monitor_reinit(pmonitor);
687 pmonitor->m_pid = fork();
688 if (pmonitor->m_pid == -1)
689 fatal("fork of unprivileged child failed");
690 else if (pmonitor->m_pid != 0) {
691 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
692 close(pmonitor->m_recvfd);
693 buffer_clear(&loginmsg);
694 monitor_child_postauth(pmonitor);
700 close(pmonitor->m_sendfd);
702 /* Demote the private keys to public keys. */
703 demote_sensitive_data();
706 arc4random_buf(rnd, sizeof(rnd));
707 RAND_seed(rnd, sizeof(rnd));
709 /* Drop privileges */
710 do_setusercontext(authctxt->pw);
713 /* It is safe now to apply the key state */
714 monitor_apply_keystate(pmonitor);
717 * Tell the packet layer that authentication was successful, since
718 * this information is not part of the key state.
720 packet_set_authenticated();
724 list_hostkey_types(void)
732 for (i = 0; i < options.num_host_key_files; i++) {
733 Key *key = sensitive_data.host_keys[i];
739 if (buffer_len(&b) > 0)
740 buffer_append(&b, ",", 1);
741 p = key_ssh_name(key);
742 buffer_append(&b, p, strlen(p));
746 buffer_append(&b, "\0", 1);
747 ret = xstrdup(buffer_ptr(&b));
749 debug("list_hostkey_types: %s", ret);
754 get_hostkey_by_type(int type)
758 for (i = 0; i < options.num_host_key_files; i++) {
759 Key *key = sensitive_data.host_keys[i];
760 if (key != NULL && key->type == type)
767 get_hostkey_by_index(int ind)
769 if (ind < 0 || ind >= options.num_host_key_files)
771 return (sensitive_data.host_keys[ind]);
775 get_hostkey_index(Key *key)
779 for (i = 0; i < options.num_host_key_files; i++) {
780 if (key == sensitive_data.host_keys[i])
787 * returns 1 if connection should be dropped, 0 otherwise.
788 * dropping starts at connection #max_startups_begin with a probability
789 * of (max_startups_rate/100). the probability increases linearly until
790 * all connections are dropped for startups > max_startups
793 drop_connection(int startups)
797 if (startups < options.max_startups_begin)
799 if (startups >= options.max_startups)
801 if (options.max_startups_rate == 100)
804 p = 100 - options.max_startups_rate;
805 p *= startups - options.max_startups_begin;
806 p /= options.max_startups - options.max_startups_begin;
807 p += options.max_startups_rate;
808 r = arc4random_uniform(100);
810 debug("drop_connection: p %d, r %d", p, r);
811 return (r < p) ? 1 : 0;
817 fprintf(stderr, "%s, %s\n",
818 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
820 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n"
821 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n"
822 " [-o option] [-p port] [-u len]\n"
828 send_rexec_state(int fd, Buffer *conf)
832 debug3("%s: entering fd = %d config len %d", __func__, fd,
836 * Protocol from reexec master to child:
837 * string configuration
838 * u_int ephemeral_key_follows
839 * bignum e (only if ephemeral_key_follows == 1)
845 * string rngseed (only if OpenSSL is not self-seeded)
848 buffer_put_cstring(&m, buffer_ptr(conf));
850 if (sensitive_data.server_key != NULL &&
851 sensitive_data.server_key->type == KEY_RSA1) {
852 buffer_put_int(&m, 1);
853 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
854 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
855 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
856 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
857 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
858 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
860 buffer_put_int(&m, 0);
862 #ifndef OPENSSL_PRNG_ONLY
863 rexec_send_rng_seed(&m);
866 if (ssh_msg_send(fd, 0, &m) == -1)
867 fatal("%s: ssh_msg_send failed", __func__);
871 debug3("%s: done", __func__);
875 recv_rexec_state(int fd, Buffer *conf)
881 debug3("%s: entering fd = %d", __func__, fd);
885 if (ssh_msg_recv(fd, &m) == -1)
886 fatal("%s: ssh_msg_recv failed", __func__);
887 if (buffer_get_char(&m) != 0)
888 fatal("%s: rexec version mismatch", __func__);
890 cp = buffer_get_string(&m, &len);
892 buffer_append(conf, cp, len + 1);
895 if (buffer_get_int(&m)) {
896 if (sensitive_data.server_key != NULL)
897 key_free(sensitive_data.server_key);
898 sensitive_data.server_key = key_new_private(KEY_RSA1);
899 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
900 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
901 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
902 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
903 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
904 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
905 rsa_generate_additional_parameters(
906 sensitive_data.server_key->rsa);
909 #ifndef OPENSSL_PRNG_ONLY
910 rexec_recv_rng_seed(&m);
915 debug3("%s: done", __func__);
920 * If requested in the environment, tell the Linux kernel's out-of-memory
921 * killer to avoid sshd. The old state will be restored when forking child
925 oom_adjust_startup(void)
927 const char *oom_adj = getenv("SSHD_OOM_ADJUST");
929 if (!oom_adj || !*oom_adj)
931 oom_adj_get(oom_adj_save, sizeof(oom_adj_save));
932 oom_adj_set(oom_adj);
939 oom_adj_set(oom_adj_save);
943 /* Accept a connection from inetd */
945 server_accept_inetd(int *sock_in, int *sock_out)
951 close(REEXEC_CONFIG_PASS_FD);
952 *sock_in = *sock_out = dup(STDIN_FILENO);
954 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
955 close(REEXEC_STARTUP_PIPE_FD);
958 *sock_in = dup(STDIN_FILENO);
959 *sock_out = dup(STDOUT_FILENO);
962 * We intentionally do not close the descriptors 0, 1, and 2
963 * as our code for setting the descriptors won't work if
964 * ttyfd happens to be one of those.
966 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
967 dup2(fd, STDIN_FILENO);
968 dup2(fd, STDOUT_FILENO);
969 if (fd > STDOUT_FILENO)
972 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
976 * Listen for TCP connections
981 int ret, listen_sock, on = 1;
983 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
985 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
986 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
988 if (num_listen_socks >= MAX_LISTEN_SOCKS)
989 fatal("Too many listen sockets. "
990 "Enlarge MAX_LISTEN_SOCKS");
991 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
992 ntop, sizeof(ntop), strport, sizeof(strport),
993 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
994 error("getnameinfo failed: %.100s",
995 ssh_gai_strerror(ret));
998 /* Create socket for listening. */
999 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1001 if (listen_sock < 0) {
1002 /* kernel may not support ipv6 */
1003 verbose("socket: %.100s", strerror(errno));
1006 if (set_nonblock(listen_sock) == -1) {
1011 * Set socket options.
1012 * Allow local port reuse in TIME_WAIT.
1014 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1015 &on, sizeof(on)) == -1)
1016 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1019 /* Only communicate in IPv6 over AF_INET6 sockets. */
1020 if (ai->ai_family == AF_INET6) {
1021 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY,
1022 &on, sizeof(on)) == -1)
1023 error("setsockopt IPV6_V6ONLY: %s",
1028 debug("Bind to port %s on %s.", strport, ntop);
1030 /* Bind the socket to the desired port. */
1031 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1032 error("Bind to port %s on %s failed: %.200s.",
1033 strport, ntop, strerror(errno));
1037 listen_socks[num_listen_socks] = listen_sock;
1040 /* Start listening on the port. */
1041 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1042 fatal("listen on [%s]:%s: %.100s",
1043 ntop, strport, strerror(errno));
1044 logit("Server listening on %s port %s.", ntop, strport);
1046 freeaddrinfo(options.listen_addrs);
1048 if (!num_listen_socks)
1049 fatal("Cannot bind any address.");
1053 * The main TCP accept loop. Note that, for the non-debug case, returns
1054 * from this function are in a forked subprocess.
1057 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1060 int i, j, ret, maxfd;
1061 int key_used = 0, startups = 0;
1062 int startup_p[2] = { -1 , -1 };
1063 struct sockaddr_storage from;
1067 /* setup fd set for accept */
1070 for (i = 0; i < num_listen_socks; i++)
1071 if (listen_socks[i] > maxfd)
1072 maxfd = listen_socks[i];
1073 /* pipes connected to unauthenticated childs */
1074 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1075 for (i = 0; i < options.max_startups; i++)
1076 startup_pipes[i] = -1;
1079 * Stay listening for connections until the system crashes or
1080 * the daemon is killed with a signal.
1083 if (received_sighup)
1087 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1090 for (i = 0; i < num_listen_socks; i++)
1091 FD_SET(listen_socks[i], fdset);
1092 for (i = 0; i < options.max_startups; i++)
1093 if (startup_pipes[i] != -1)
1094 FD_SET(startup_pipes[i], fdset);
1096 /* Wait in select until there is a connection. */
1097 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1098 if (ret < 0 && errno != EINTR)
1099 error("select: %.100s", strerror(errno));
1100 if (received_sigterm) {
1101 logit("Received signal %d; terminating.",
1102 (int) received_sigterm);
1103 close_listen_socks();
1104 unlink(options.pid_file);
1107 if (key_used && key_do_regen) {
1108 generate_ephemeral_server_key();
1115 for (i = 0; i < options.max_startups; i++)
1116 if (startup_pipes[i] != -1 &&
1117 FD_ISSET(startup_pipes[i], fdset)) {
1119 * the read end of the pipe is ready
1120 * if the child has closed the pipe
1121 * after successful authentication
1122 * or if the child has died
1124 close(startup_pipes[i]);
1125 startup_pipes[i] = -1;
1128 for (i = 0; i < num_listen_socks; i++) {
1129 if (!FD_ISSET(listen_socks[i], fdset))
1131 fromlen = sizeof(from);
1132 *newsock = accept(listen_socks[i],
1133 (struct sockaddr *)&from, &fromlen);
1135 if (errno != EINTR && errno != EAGAIN &&
1136 errno != EWOULDBLOCK)
1137 error("accept: %.100s", strerror(errno));
1140 if (unset_nonblock(*newsock) == -1) {
1144 if (drop_connection(startups) == 1) {
1145 debug("drop connection #%d", startups);
1149 if (pipe(startup_p) == -1) {
1154 if (rexec_flag && socketpair(AF_UNIX,
1155 SOCK_STREAM, 0, config_s) == -1) {
1156 error("reexec socketpair: %s",
1159 close(startup_p[0]);
1160 close(startup_p[1]);
1164 for (j = 0; j < options.max_startups; j++)
1165 if (startup_pipes[j] == -1) {
1166 startup_pipes[j] = startup_p[0];
1167 if (maxfd < startup_p[0])
1168 maxfd = startup_p[0];
1174 * Got connection. Fork a child to handle it, unless
1175 * we are in debugging mode.
1179 * In debugging mode. Close the listening
1180 * socket, and start processing the
1181 * connection without forking.
1183 debug("Server will not fork when running in debugging mode.");
1184 close_listen_socks();
1185 *sock_in = *newsock;
1186 *sock_out = *newsock;
1187 close(startup_p[0]);
1188 close(startup_p[1]);
1192 send_rexec_state(config_s[0],
1200 * Normal production daemon. Fork, and have
1201 * the child process the connection. The
1202 * parent continues listening.
1204 platform_pre_fork();
1205 if ((pid = fork()) == 0) {
1207 * Child. Close the listening and
1208 * max_startup sockets. Start using
1209 * the accepted socket. Reinitialize
1210 * logging (since our pid has changed).
1211 * We break out of the loop to handle
1214 platform_post_fork_child();
1215 startup_pipe = startup_p[1];
1216 close_startup_pipes();
1217 close_listen_socks();
1218 *sock_in = *newsock;
1219 *sock_out = *newsock;
1220 log_init(__progname,
1222 options.log_facility,
1229 /* Parent. Stay in the loop. */
1230 platform_post_fork_parent(pid);
1232 error("fork: %.100s", strerror(errno));
1234 debug("Forked child %ld.", (long)pid);
1236 close(startup_p[1]);
1239 send_rexec_state(config_s[0], &cfg);
1245 * Mark that the key has been used (it
1246 * was "given" to the child).
1248 if ((options.protocol & SSH_PROTO_1) &&
1250 /* Schedule server key regeneration alarm. */
1251 signal(SIGALRM, key_regeneration_alarm);
1252 alarm(options.key_regeneration_time);
1259 * Ensure that our random state differs
1260 * from that of the child
1265 /* child process check (or debug mode) */
1266 if (num_listen_socks < 0)
1273 * Main program for the daemon.
1276 main(int ac, char **av)
1278 extern char *optarg;
1281 int sock_in = -1, sock_out = -1, newsock = -1;
1282 const char *remote_ip;
1283 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1285 char *line, *p, *cp;
1286 int config_s[2] = { -1 , -1 };
1287 u_int64_t ibytes, obytes;
1292 #ifdef HAVE_SECUREWARE
1293 (void)set_auth_parameters(ac, av);
1295 __progname = ssh_get_progname(av[0]);
1298 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1301 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1302 for (i = 0; i < ac; i++)
1303 saved_argv[i] = xstrdup(av[i]);
1304 saved_argv[i] = NULL;
1306 #ifndef HAVE_SETPROCTITLE
1307 /* Prepare for later setproctitle emulation */
1308 compat_init_setproctitle(ac, av);
1312 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1313 debug("setgroups(): %.200s", strerror(errno));
1315 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1318 /* Initialize configuration options to their default values. */
1319 initialize_server_options(&options);
1321 /* Parse command-line arguments. */
1322 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1325 options.address_family = AF_INET;
1328 options.address_family = AF_INET6;
1331 config_file_name = optarg;
1334 if (debug_flag == 0) {
1336 options.log_level = SYSLOG_LEVEL_DEBUG1;
1337 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1338 options.log_level++;
1360 if (options.log_level == SYSLOG_LEVEL_QUIET) {
1361 options.log_level = SYSLOG_LEVEL_SILENT;
1363 else if (options.log_level != SYSLOG_LEVEL_SILENT) {
1364 options.log_level = SYSLOG_LEVEL_QUIET;
1368 options.server_key_bits = (int)strtonum(optarg, 256,
1372 options.ports_from_cmdline = 1;
1373 if (options.num_ports >= MAX_PORTS) {
1374 fprintf(stderr, "too many ports.\n");
1377 options.ports[options.num_ports++] = a2port(optarg);
1378 if (options.ports[options.num_ports-1] <= 0) {
1379 fprintf(stderr, "Bad port number.\n");
1384 if ((options.login_grace_time = convtime(optarg)) == -1) {
1385 fprintf(stderr, "Invalid login grace time.\n");
1390 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1391 fprintf(stderr, "Invalid key regeneration interval.\n");
1396 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1397 fprintf(stderr, "too many host keys.\n");
1400 options.host_key_files[options.num_host_key_files++] = optarg;
1410 while ((p = strsep(&cp, ",")) && *p != '\0') {
1411 if (strncmp(p, "addr=", 5) == 0)
1412 test_addr = xstrdup(p + 5);
1413 else if (strncmp(p, "host=", 5) == 0)
1414 test_host = xstrdup(p + 5);
1415 else if (strncmp(p, "user=", 5) == 0)
1416 test_user = xstrdup(p + 5);
1418 fprintf(stderr, "Invalid test "
1419 "mode specification %s\n", p);
1425 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1426 if (utmp_len > MAXHOSTNAMELEN) {
1427 fprintf(stderr, "Invalid utmp length.\n");
1432 line = xstrdup(optarg);
1433 if (process_server_config_line(&options, line,
1434 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1444 if (rexeced_flag || inetd_flag)
1446 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1447 fatal("sshd re-exec requires execution with an absolute path");
1449 closefrom(REEXEC_MIN_FREE_FD);
1451 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1453 SSLeay_add_all_algorithms();
1456 * Force logging to stderr until we have loaded the private host
1457 * key (unless started from inetd)
1459 log_init(__progname,
1460 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1461 SYSLOG_LEVEL_INFO : options.log_level,
1462 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1463 SYSLOG_FACILITY_AUTH : options.log_facility,
1464 log_stderr || !inetd_flag);
1467 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1468 * root's environment
1470 if (getenv("KRB5CCNAME") != NULL)
1471 unsetenv("KRB5CCNAME");
1474 /* Cray can define user privs drop all privs now!
1475 * Not needed on PRIV_SU systems!
1480 sensitive_data.server_key = NULL;
1481 sensitive_data.ssh1_host_key = NULL;
1482 sensitive_data.have_ssh1_key = 0;
1483 sensitive_data.have_ssh2_key = 0;
1486 * If we're doing an extended config test, make sure we have all of
1487 * the parameters we need. If we're not doing an extended test,
1488 * do not silently ignore connection test params.
1490 if (test_flag >= 2 &&
1491 (test_user != NULL || test_host != NULL || test_addr != NULL)
1492 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1493 fatal("user, host and addr are all required when testing "
1495 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1497 fatal("Config test connection parameter (-C) provided without "
1500 /* Fetch our configuration */
1503 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1505 load_server_config(config_file_name, &cfg);
1507 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1508 &cfg, NULL, NULL, NULL);
1512 /* Fill in default values for those options not explicitly set. */
1513 fill_default_server_options(&options);
1515 /* challenge-response is implemented via keyboard interactive */
1516 if (options.challenge_response_authentication)
1517 options.kbd_interactive_authentication = 1;
1519 /* set default channel AF */
1520 channel_set_af(options.address_family);
1522 /* Check that there are no remaining arguments. */
1524 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1528 debug("sshd version %.100s", SSH_RELEASE);
1530 /* Store privilege separation user for later use if required. */
1531 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1532 if (use_privsep || options.kerberos_authentication)
1533 fatal("Privilege separation user %s does not exist",
1536 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1537 privsep_pw = pwcopy(privsep_pw);
1538 xfree(privsep_pw->pw_passwd);
1539 privsep_pw->pw_passwd = xstrdup("*");
1543 /* load private host keys */
1544 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1546 for (i = 0; i < options.num_host_key_files; i++)
1547 sensitive_data.host_keys[i] = NULL;
1549 for (i = 0; i < options.num_host_key_files; i++) {
1550 key = key_load_private(options.host_key_files[i], "", NULL);
1551 sensitive_data.host_keys[i] = key;
1553 error("Could not load host key: %s",
1554 options.host_key_files[i]);
1555 sensitive_data.host_keys[i] = NULL;
1558 if (reject_blacklisted_key(key, 1) == 1) {
1560 sensitive_data.host_keys[i] = NULL;
1563 switch (key->type) {
1565 sensitive_data.ssh1_host_key = key;
1566 sensitive_data.have_ssh1_key = 1;
1570 sensitive_data.have_ssh2_key = 1;
1573 debug("private host key: #%d type %d %s", i, key->type,
1576 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1577 logit("Disabling protocol version 1. Could not load host key");
1578 options.protocol &= ~SSH_PROTO_1;
1581 /* The GSSAPI key exchange can run without a host key */
1582 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1583 logit("Disabling protocol version 2. Could not load host key");
1584 options.protocol &= ~SSH_PROTO_2;
1587 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1588 logit("sshd: no hostkeys available -- exiting.");
1592 /* Check certain values for sanity. */
1593 if (options.protocol & SSH_PROTO_1) {
1594 if (options.server_key_bits < 512 ||
1595 options.server_key_bits > 32768) {
1596 fprintf(stderr, "Bad server key size.\n");
1600 * Check that server and host key lengths differ sufficiently. This
1601 * is necessary to make double encryption work with rsaref. Oh, I
1602 * hate software patents. I dont know if this can go? Niels
1604 if (options.server_key_bits >
1605 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1606 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1607 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1608 SSH_KEY_BITS_RESERVED) {
1609 options.server_key_bits =
1610 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1611 SSH_KEY_BITS_RESERVED;
1612 debug("Forcing server key to %d bits to make it differ from host key.",
1613 options.server_key_bits);
1620 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1621 (S_ISDIR(st.st_mode) == 0))
1622 fatal("Missing privilege separation directory: %s",
1623 _PATH_PRIVSEP_CHROOT_DIR);
1626 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1627 (st.st_uid != getuid () ||
1628 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1630 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1632 fatal("%s must be owned by root and not group or "
1633 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1636 if (test_flag > 1) {
1637 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1638 parse_server_match_config(&options, test_user,
1639 test_host, test_addr);
1640 dump_config(&options);
1643 /* Configuration looks good, so exit if in test mode. */
1648 * Clear out any supplemental groups we may have inherited. This
1649 * prevents inadvertent creation of files with bad modes (in the
1650 * portable version at least, it's certainly possible for PAM
1651 * to create a file, and we can't control the code in every
1652 * module which might be used).
1654 if (setgroups(0, NULL) < 0)
1655 debug("setgroups() failed: %.200s", strerror(errno));
1658 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1659 for (i = 0; i < rexec_argc; i++) {
1660 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1661 rexec_argv[i] = saved_argv[i];
1663 rexec_argv[rexec_argc] = "-R";
1664 rexec_argv[rexec_argc + 1] = NULL;
1667 /* Ensure that umask disallows at least group and world write */
1668 new_umask = umask(0077) | 0022;
1669 (void) umask(new_umask);
1671 /* Initialize the log (it is reinitialized below in case we forked). */
1672 if (debug_flag && (!inetd_flag || rexeced_flag))
1674 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1677 * If not in debugging mode, and not started from inetd, disconnect
1678 * from the controlling terminal, and fork. The original process
1681 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1684 #endif /* TIOCNOTTY */
1685 if (daemon(0, 0) < 0)
1686 fatal("daemon() failed: %.200s", strerror(errno));
1688 /* Disconnect from the controlling tty. */
1690 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1692 (void) ioctl(fd, TIOCNOTTY, NULL);
1695 #endif /* TIOCNOTTY */
1697 /* Reinitialize the log (because of the fork above). */
1698 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1700 /* Initialize the random number generator. */
1703 /* Chdir to the root directory so that the current disk can be
1704 unmounted if desired. */
1707 /* ignore SIGPIPE */
1708 signal(SIGPIPE, SIG_IGN);
1711 /* Adjust out-of-memory killer */
1712 oom_adjust_startup();
1715 /* Get a connection, either from inetd or a listening TCP socket */
1717 server_accept_inetd(&sock_in, &sock_out);
1721 if (options.protocol & SSH_PROTO_1)
1722 generate_ephemeral_server_key();
1724 signal(SIGHUP, sighup_handler);
1725 signal(SIGCHLD, main_sigchld_handler);
1726 signal(SIGTERM, sigterm_handler);
1727 signal(SIGQUIT, sigterm_handler);
1730 * Write out the pid file after the sigterm handler
1731 * is setup and the listen sockets are bound
1734 FILE *f = fopen(options.pid_file, "w");
1737 error("Couldn't create pid file \"%s\": %s",
1738 options.pid_file, strerror(errno));
1740 fprintf(f, "%ld\n", (long) getpid());
1745 /* Accept a connection and return in a forked child */
1746 server_accept_loop(&sock_in, &sock_out,
1747 &newsock, config_s);
1750 /* This is the child processing a new connection. */
1751 setproctitle("%s", "[accepted]");
1758 * Create a new session and process group since the 4.4BSD
1759 * setlogin() affects the entire process group. We don't
1760 * want the child to be able to affect the parent.
1762 #if !defined(SSHD_ACQUIRES_CTTY)
1764 * If setsid is called, on some platforms sshd will later acquire a
1765 * controlling terminal which will result in "could not set
1766 * controlling tty" errors.
1768 if (!debug_flag && !inetd_flag && setsid() < 0)
1769 error("setsid: %.100s", strerror(errno));
1775 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1776 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1777 dup2(newsock, STDIN_FILENO);
1778 dup2(STDIN_FILENO, STDOUT_FILENO);
1779 if (startup_pipe == -1)
1780 close(REEXEC_STARTUP_PIPE_FD);
1782 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1784 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1786 if (startup_pipe != -1)
1787 close(startup_pipe);
1789 execv(rexec_argv[0], rexec_argv);
1791 /* Reexec has failed, fall back and continue */
1792 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1793 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1794 log_init(__progname, options.log_level,
1795 options.log_facility, log_stderr);
1798 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1800 close(REEXEC_CONFIG_PASS_FD);
1801 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1802 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1803 dup2(fd, STDIN_FILENO);
1804 dup2(fd, STDOUT_FILENO);
1805 if (fd > STDERR_FILENO)
1808 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1809 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1813 * Disable the key regeneration alarm. We will not regenerate the
1814 * key since we are no longer in a position to give it to anyone. We
1815 * will not restart on SIGHUP since it no longer makes sense.
1818 signal(SIGALRM, SIG_DFL);
1819 signal(SIGHUP, SIG_DFL);
1820 signal(SIGTERM, SIG_DFL);
1821 signal(SIGQUIT, SIG_DFL);
1822 signal(SIGCHLD, SIG_DFL);
1823 signal(SIGINT, SIG_DFL);
1826 * Register our connection. This turns encryption off because we do
1829 packet_set_connection(sock_in, sock_out);
1830 packet_set_server();
1832 /* Set SO_KEEPALIVE if requested. */
1833 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1834 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1835 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1837 if ((remote_port = get_remote_port()) < 0) {
1838 debug("get_remote_port failed");
1843 * We use get_canonical_hostname with usedns = 0 instead of
1844 * get_remote_ipaddr here so IP options will be checked.
1846 (void) get_canonical_hostname(0);
1848 * The rest of the code depends on the fact that
1849 * get_remote_ipaddr() caches the remote ip, even if
1850 * the socket goes away.
1852 remote_ip = get_remote_ipaddr();
1854 #ifdef SSH_AUDIT_EVENTS
1855 audit_connection_from(remote_ip, remote_port);
1858 allow_severity = options.log_facility|LOG_INFO;
1859 deny_severity = options.log_facility|LOG_WARNING;
1860 /* Check whether logins are denied from this host. */
1861 if (packet_connection_is_on_socket()) {
1862 struct request_info req;
1864 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1867 if (!hosts_access(&req)) {
1868 debug("Connection refused by tcp wrapper");
1871 fatal("libwrap refuse returns");
1874 #endif /* LIBWRAP */
1876 /* Log the connection. */
1877 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1879 #ifdef USE_SECURITY_SESSION_API
1881 * Create a new security session for use by the new user login if
1882 * the current session is the root session or we are not launched
1883 * by inetd (eg: debugging mode or server mode). We do not
1884 * necessarily need to create a session if we are launched from
1885 * inetd because Panther xinetd will create a session for us.
1887 * The only case where this logic will fail is if there is an
1888 * inetd running in a non-root session which is not creating
1889 * new sessions for us. Then all the users will end up in the
1890 * same session (bad).
1892 * When the client exits, the session will be destroyed for us
1895 * We must create the session before any credentials are stored
1896 * (including AFS pags, which happens a few lines below).
1900 SecuritySessionId sid = 0;
1901 SessionAttributeBits sattrs = 0;
1903 err = SessionGetInfo(callerSecuritySession, &sid, &sattrs);
1905 error("SessionGetInfo() failed with error %.8X",
1908 debug("Current Session ID is %.8X / Session Attributes are %.8X",
1909 (unsigned) sid, (unsigned) sattrs);
1911 if (inetd_flag && !(sattrs & sessionIsRoot))
1912 debug("Running in inetd mode in a non-root session... "
1913 "assuming inetd created the session for us.");
1915 debug("Creating new security session...");
1916 err = SessionCreate(0, sessionHasTTY | sessionIsRemote);
1918 error("SessionCreate() failed with error %.8X",
1921 err = SessionGetInfo(callerSecuritySession, &sid,
1924 error("SessionGetInfo() failed with error %.8X",
1927 debug("New Session ID is %.8X / Session Attributes are %.8X",
1928 (unsigned) sid, (unsigned) sattrs);
1934 * We don't want to listen forever unless the other side
1935 * successfully authenticates itself. So we set up an alarm which is
1936 * cleared after successful authentication. A limit of zero
1937 * indicates no limit. Note that we don't set the alarm in debugging
1938 * mode; it is just annoying to have the server exit just when you
1939 * are about to discover the bug.
1941 signal(SIGALRM, grace_alarm_handler);
1943 alarm(options.login_grace_time);
1945 sshd_exchange_identification(sock_in, sock_out);
1947 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1948 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1949 generate_ephemeral_server_key();
1951 packet_set_nonblocking();
1953 /* allocate authentication context */
1954 authctxt = xcalloc(1, sizeof(*authctxt));
1956 authctxt->loginmsg = &loginmsg;
1958 /* XXX global for cleanup, access from other modules */
1959 the_authctxt = authctxt;
1961 /* prepare buffer to collect messages to display to user after login */
1962 buffer_init(&loginmsg);
1965 if (privsep_preauth(authctxt) == 1)
1968 /* perform the key exchange */
1969 /* authenticate user and start session */
1972 do_authentication2(authctxt);
1975 do_authentication(authctxt);
1978 * If we use privilege separation, the unprivileged child transfers
1979 * the current keystate and exits
1982 mm_send_keystate(pmonitor);
1988 * Cancel the alarm we set to limit the time taken for
1992 signal(SIGALRM, SIG_DFL);
1993 authctxt->authenticated = 1;
1994 if (startup_pipe != -1) {
1995 close(startup_pipe);
1999 #ifdef SSH_AUDIT_EVENTS
2000 audit_event(SSH_AUTH_SUCCESS);
2004 if (options.gss_authentication) {
2005 temporarily_use_uid(authctxt->pw);
2006 ssh_gssapi_storecreds();
2011 if (options.use_pam) {
2018 * In privilege separation, we fork another child and prepare
2019 * file descriptor passing.
2022 privsep_postauth(authctxt);
2023 /* the monitor process [priv] will not return */
2025 destroy_sensitive_data();
2028 packet_set_timeout(options.client_alive_interval,
2029 options.client_alive_count_max);
2031 /* Start session. */
2032 do_authenticated(authctxt);
2034 /* The connection has been terminated. */
2035 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2036 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2037 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
2039 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2042 if (options.use_pam)
2044 #endif /* USE_PAM */
2046 #ifdef SSH_AUDIT_EVENTS
2047 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2059 * Decrypt session_key_int using our private server key and private host key
2060 * (key with larger modulus first).
2063 ssh1_session_key(BIGNUM *session_key_int)
2067 if (BN_cmp(sensitive_data.server_key->rsa->n,
2068 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2069 /* Server key has bigger modulus. */
2070 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2071 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2072 SSH_KEY_BITS_RESERVED) {
2073 fatal("do_connection: %s: "
2074 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2075 get_remote_ipaddr(),
2076 BN_num_bits(sensitive_data.server_key->rsa->n),
2077 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2078 SSH_KEY_BITS_RESERVED);
2080 if (rsa_private_decrypt(session_key_int, session_key_int,
2081 sensitive_data.server_key->rsa) <= 0)
2083 if (rsa_private_decrypt(session_key_int, session_key_int,
2084 sensitive_data.ssh1_host_key->rsa) <= 0)
2087 /* Host key has bigger modulus (or they are equal). */
2088 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2089 BN_num_bits(sensitive_data.server_key->rsa->n) +
2090 SSH_KEY_BITS_RESERVED) {
2091 fatal("do_connection: %s: "
2092 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2093 get_remote_ipaddr(),
2094 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2095 BN_num_bits(sensitive_data.server_key->rsa->n),
2096 SSH_KEY_BITS_RESERVED);
2098 if (rsa_private_decrypt(session_key_int, session_key_int,
2099 sensitive_data.ssh1_host_key->rsa) < 0)
2101 if (rsa_private_decrypt(session_key_int, session_key_int,
2102 sensitive_data.server_key->rsa) < 0)
2115 BIGNUM *session_key_int;
2116 u_char session_key[SSH_SESSION_KEY_LENGTH];
2118 u_int cipher_type, auth_mask, protocol_flags;
2121 * Generate check bytes that the client must send back in the user
2122 * packet in order for it to be accepted; this is used to defy ip
2123 * spoofing attacks. Note that this only works against somebody
2124 * doing IP spoofing from a remote machine; any machine on the local
2125 * network can still see outgoing packets and catch the random
2126 * cookie. This only affects rhosts authentication, and this is one
2127 * of the reasons why it is inherently insecure.
2129 arc4random_buf(cookie, sizeof(cookie));
2132 * Send our public key. We include in the packet 64 bits of random
2133 * data that must be matched in the reply in order to prevent IP
2136 packet_start(SSH_SMSG_PUBLIC_KEY);
2137 for (i = 0; i < 8; i++)
2138 packet_put_char(cookie[i]);
2140 /* Store our public server RSA key. */
2141 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2142 packet_put_bignum(sensitive_data.server_key->rsa->e);
2143 packet_put_bignum(sensitive_data.server_key->rsa->n);
2145 /* Store our public host RSA key. */
2146 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2147 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2148 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2150 /* Put protocol flags. */
2151 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2153 /* Declare which ciphers we support. */
2154 packet_put_int(cipher_mask_ssh1(0));
2156 /* Declare supported authentication types. */
2158 if (options.rhosts_rsa_authentication)
2159 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2160 if (options.rsa_authentication)
2161 auth_mask |= 1 << SSH_AUTH_RSA;
2162 if (options.challenge_response_authentication == 1)
2163 auth_mask |= 1 << SSH_AUTH_TIS;
2164 if (options.password_authentication)
2165 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2166 packet_put_int(auth_mask);
2168 /* Send the packet and wait for it to be sent. */
2170 packet_write_wait();
2172 debug("Sent %d bit server key and %d bit host key.",
2173 BN_num_bits(sensitive_data.server_key->rsa->n),
2174 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2176 /* Read clients reply (cipher type and session key). */
2177 packet_read_expect(SSH_CMSG_SESSION_KEY);
2179 /* Get cipher type and check whether we accept this. */
2180 cipher_type = packet_get_char();
2182 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2183 packet_disconnect("Warning: client selects unsupported cipher.");
2185 /* Get check bytes from the packet. These must match those we
2186 sent earlier with the public key packet. */
2187 for (i = 0; i < 8; i++)
2188 if (cookie[i] != packet_get_char())
2189 packet_disconnect("IP Spoofing check bytes do not match.");
2191 debug("Encryption type: %.200s", cipher_name(cipher_type));
2193 /* Get the encrypted integer. */
2194 if ((session_key_int = BN_new()) == NULL)
2195 fatal("do_ssh1_kex: BN_new failed");
2196 packet_get_bignum(session_key_int);
2198 protocol_flags = packet_get_int();
2199 packet_set_protocol_flags(protocol_flags);
2202 /* Decrypt session_key_int using host/server keys */
2203 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2206 * Extract session key from the decrypted integer. The key is in the
2207 * least significant 256 bits of the integer; the first byte of the
2208 * key is in the highest bits.
2211 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2212 len = BN_num_bytes(session_key_int);
2213 if (len < 0 || (u_int)len > sizeof(session_key)) {
2214 error("do_ssh1_kex: bad session key len from %s: "
2215 "session_key_int %d > sizeof(session_key) %lu",
2216 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2219 memset(session_key, 0, sizeof(session_key));
2220 BN_bn2bin(session_key_int,
2221 session_key + sizeof(session_key) - len);
2223 derive_ssh1_session_id(
2224 sensitive_data.ssh1_host_key->rsa->n,
2225 sensitive_data.server_key->rsa->n,
2226 cookie, session_id);
2228 * Xor the first 16 bytes of the session key with the
2231 for (i = 0; i < 16; i++)
2232 session_key[i] ^= session_id[i];
2236 int bytes = BN_num_bytes(session_key_int);
2237 u_char *buf = xmalloc(bytes);
2240 logit("do_connection: generating a fake encryption key");
2241 BN_bn2bin(session_key_int, buf);
2243 MD5_Update(&md, buf, bytes);
2244 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2245 MD5_Final(session_key, &md);
2247 MD5_Update(&md, session_key, 16);
2248 MD5_Update(&md, buf, bytes);
2249 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2250 MD5_Final(session_key + 16, &md);
2251 memset(buf, 0, bytes);
2253 for (i = 0; i < 16; i++)
2254 session_id[i] = session_key[i] ^ session_key[i + 16];
2256 /* Destroy the private and public keys. No longer. */
2257 destroy_sensitive_data();
2260 mm_ssh1_session_id(session_id);
2262 /* Destroy the decrypted integer. It is no longer needed. */
2263 BN_clear_free(session_key_int);
2265 /* Set the session key. From this on all communications will be encrypted. */
2266 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2268 /* Destroy our copy of the session key. It is no longer needed. */
2269 memset(session_key, 0, sizeof(session_key));
2271 debug("Received session key; encryption turned on.");
2273 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2274 packet_start(SSH_SMSG_SUCCESS);
2276 packet_write_wait();
2280 * SSH2 key exchange: diffie-hellman-group1-sha1
2287 if (options.ciphers != NULL) {
2288 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2289 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2291 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2292 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2293 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2294 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2296 if (options.macs != NULL) {
2297 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2298 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2300 if (options.compression == COMP_NONE) {
2301 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2302 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2303 } else if (options.compression == COMP_DELAYED) {
2304 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2305 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2308 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2314 char *newstr = NULL;
2315 orig = myproposal[PROPOSAL_KEX_ALGS];
2318 * If we don't have a host key, then there's no point advertising
2319 * the other key exchange algorithms
2322 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
2325 if (options.gss_keyex)
2326 gss = ssh_gssapi_server_mechanisms();
2331 xasprintf(&newstr, "%s,%s", gss, orig);
2338 * If we've got GSSAPI mechanisms, then we've got the 'null' host
2339 * key alg, but we can't tell people about it unless its the only
2340 * host key algorithm we support
2342 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
2343 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
2346 myproposal[PROPOSAL_KEX_ALGS] = newstr;
2348 fatal("No supported key exchange algorithms");
2352 /* start key exchange */
2353 kex = kex_setup(myproposal);
2354 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2355 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2356 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2357 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2359 if (options.gss_keyex) {
2360 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
2361 kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
2362 kex->kex[KEX_GSS_GEX_SHA1] = kexgss_server;
2366 kex->client_version_string=client_version_string;
2367 kex->server_version_string=server_version_string;
2368 kex->load_host_key=&get_hostkey_by_type;
2369 kex->host_key_index=&get_hostkey_index;
2373 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2375 session_id2 = kex->session_id;
2376 session_id2_len = kex->session_id_len;
2379 /* send 1st encrypted/maced/compressed message */
2380 packet_start(SSH2_MSG_IGNORE);
2381 packet_put_cstring("markus");
2383 packet_write_wait();
2388 /* server specific fatal cleanup */
2393 do_cleanup(the_authctxt);
2394 #ifdef SSH_AUDIT_EVENTS
2395 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2396 if (!use_privsep || mm_is_monitor())
2397 audit_event(SSH_CONNECTION_ABANDON);