1 /* $OpenBSD: sshd.c,v 1.355 2008/02/14 13:10:31 mbalmer 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"
74 #include <openssl/dh.h>
75 #include <openssl/bn.h>
76 #include <openssl/md5.h>
77 #include <openssl/rand.h>
78 #include "openbsd-compat/openssl-compat.h"
80 #ifdef HAVE_SECUREWARE
81 #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"
120 #include "monitor_fdpass.h"
135 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
136 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
137 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
138 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
140 extern char *__progname;
142 /* Server configuration options. */
143 ServerOptions options;
145 /* Name of the server configuration file. */
146 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
149 * Debug mode flag. This can be set on the command line. If debug
150 * mode is enabled, extra debugging output will be sent to the system
151 * log, the daemon will not go to background, and will exit after processing
152 * the first connection.
156 /* Flag indicating that the daemon should only test the configuration and keys. */
159 /* Flag indicating that the daemon is being started from inetd. */
162 /* Flag indicating that sshd should not detach and become a daemon. */
163 int no_daemon_flag = 0;
165 /* debug goes to stderr unless inetd_flag is set */
168 /* Saved arguments to main(). */
173 int rexeced_flag = 0;
179 * The sockets that the server is listening; this is used in the SIGHUP
182 #define MAX_LISTEN_SOCKS 16
183 int listen_socks[MAX_LISTEN_SOCKS];
184 int num_listen_socks = 0;
187 * the client's version string, passed by sshd2 in compat mode. if != NULL,
188 * sshd will skip the version-number exchange
190 char *client_version_string = NULL;
191 char *server_version_string = NULL;
193 /* for rekeying XXX fixme */
197 * Any really sensitive data in the application is contained in this
198 * structure. The idea is that this structure could be locked into memory so
199 * that the pages do not get written into swap. However, there are some
200 * problems. The private key contains BIGNUMs, and we do not (in principle)
201 * have access to the internals of them, and locking just the structure is
202 * not very useful. Currently, memory locking is not implemented.
205 Key *server_key; /* ephemeral server key */
206 Key *ssh1_host_key; /* ssh1 host key */
207 Key **host_keys; /* all private host keys */
210 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
214 * Flag indicating whether the RSA server key needs to be regenerated.
215 * Is set in the SIGALRM handler and cleared when the key is regenerated.
217 static volatile sig_atomic_t key_do_regen = 0;
219 /* This is set to true when a signal is received. */
220 static volatile sig_atomic_t received_sighup = 0;
221 static volatile sig_atomic_t received_sigterm = 0;
223 /* session identifier, used by RSA-auth */
224 u_char session_id[16];
227 u_char *session_id2 = NULL;
228 u_int session_id2_len = 0;
230 /* record remote hostname or ip */
231 u_int utmp_len = MAXHOSTNAMELEN;
233 /* options.max_startup sized array of fd ints */
234 int *startup_pipes = NULL;
235 int startup_pipe; /* in child */
237 /* variables used for privilege separation */
238 int use_privsep = -1;
239 struct monitor *pmonitor = NULL;
241 /* global authentication context */
242 Authctxt *the_authctxt = NULL;
244 /* sshd_config buffer */
247 /* message to be displayed after login */
250 /* Unprivileged user */
251 struct passwd *privsep_pw = NULL;
253 /* Prototypes for various functions defined later in this file. */
254 void destroy_sensitive_data(void);
255 void demote_sensitive_data(void);
257 static void do_ssh1_kex(void);
258 static void do_ssh2_kex(void);
261 * Close all listening sockets
264 close_listen_socks(void)
268 for (i = 0; i < num_listen_socks; i++)
269 close(listen_socks[i]);
270 num_listen_socks = -1;
274 close_startup_pipes(void)
279 for (i = 0; i < options.max_startups; i++)
280 if (startup_pipes[i] != -1)
281 close(startup_pipes[i]);
285 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
286 * the effect is to reread the configuration file (and to regenerate
292 sighup_handler(int sig)
294 int save_errno = errno;
297 signal(SIGHUP, sighup_handler);
302 * Called from the main program after receiving SIGHUP.
303 * Restarts the server.
308 logit("Received SIGHUP; restarting.");
309 close_listen_socks();
310 close_startup_pipes();
311 alarm(0); /* alarm timer persists across exec */
312 execv(saved_argv[0], saved_argv);
313 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
319 * Generic signal handler for terminating signals in the master daemon.
323 sigterm_handler(int sig)
325 received_sigterm = sig;
329 * SIGCHLD handler. This is called whenever a child dies. This will then
330 * reap any zombies left by exited children.
334 main_sigchld_handler(int sig)
336 int save_errno = errno;
340 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
341 (pid < 0 && errno == EINTR))
344 signal(SIGCHLD, main_sigchld_handler);
349 * Signal handler for the alarm after the login grace period has expired.
353 grace_alarm_handler(int sig)
355 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
356 kill(pmonitor->m_pid, SIGALRM);
358 /* Log error and exit. */
359 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
363 * Signal handler for the key regeneration alarm. Note that this
364 * alarm only occurs in the daemon waiting for connections, and it does not
365 * do anything with the private key or random state before forking.
366 * Thus there should be no concurrency control/asynchronous execution
370 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 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
386 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
394 key_regeneration_alarm(int sig)
396 int save_errno = errno;
398 signal(SIGALRM, SIG_DFL);
404 sshd_exchange_identification(int sock_in, int sock_out)
408 int remote_major, remote_minor;
411 char buf[256]; /* Must not be larger than remote_version. */
412 char remote_version[256]; /* Must be at least as big as buf. */
414 if ((options.protocol & SSH_PROTO_1) &&
415 (options.protocol & SSH_PROTO_2)) {
416 major = PROTOCOL_MAJOR_1;
418 } else if (options.protocol & SSH_PROTO_2) {
419 major = PROTOCOL_MAJOR_2;
420 minor = PROTOCOL_MINOR_2;
422 major = PROTOCOL_MAJOR_1;
423 minor = PROTOCOL_MINOR_1;
425 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
426 server_version_string = xstrdup(buf);
428 /* Send our protocol version identification. */
429 if (atomicio(vwrite, sock_out, server_version_string,
430 strlen(server_version_string))
431 != strlen(server_version_string)) {
432 logit("Could not write ident string to %s", get_remote_ipaddr());
436 /* Read other sides version identification. */
437 memset(buf, 0, sizeof(buf));
438 for (i = 0; i < sizeof(buf) - 1; i++) {
439 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
440 logit("Did not receive identification string from %s",
441 get_remote_ipaddr());
444 if (buf[i] == '\r') {
446 /* Kludge for F-Secure Macintosh < 1.0.2 */
448 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
452 if (buf[i] == '\n') {
457 buf[sizeof(buf) - 1] = 0;
458 client_version_string = xstrdup(buf);
461 * Check that the versions match. In future this might accept
462 * several versions and set appropriate flags to handle them.
464 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
465 &remote_major, &remote_minor, remote_version) != 3) {
466 s = "Protocol mismatch.\n";
467 (void) atomicio(vwrite, sock_out, s, strlen(s));
470 logit("Bad protocol version identification '%.100s' from %s",
471 client_version_string, get_remote_ipaddr());
474 debug("Client protocol version %d.%d; client software version %.100s",
475 remote_major, remote_minor, remote_version);
477 compat_datafellows(remote_version);
479 if (datafellows & SSH_BUG_PROBE) {
480 logit("probed from %s with %s. Don't panic.",
481 get_remote_ipaddr(), client_version_string);
485 if (datafellows & SSH_BUG_SCANNER) {
486 logit("scanned from %s with %s. Don't panic.",
487 get_remote_ipaddr(), client_version_string);
492 switch (remote_major) {
494 if (remote_minor == 99) {
495 if (options.protocol & SSH_PROTO_2)
501 if (!(options.protocol & SSH_PROTO_1)) {
505 if (remote_minor < 3) {
506 packet_disconnect("Your ssh version is too old and "
507 "is no longer supported. Please install a newer version.");
508 } else if (remote_minor == 3) {
509 /* note that this disables agent-forwarding */
514 if (options.protocol & SSH_PROTO_2) {
523 chop(server_version_string);
524 debug("Local version string %.200s", server_version_string);
527 s = "Protocol major versions differ.\n";
528 (void) atomicio(vwrite, sock_out, s, strlen(s));
531 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
533 server_version_string, client_version_string);
538 /* Destroy the host and server keys. They will no longer be needed. */
540 destroy_sensitive_data(void)
544 if (sensitive_data.server_key) {
545 key_free(sensitive_data.server_key);
546 sensitive_data.server_key = NULL;
548 for (i = 0; i < options.num_host_key_files; i++) {
549 if (sensitive_data.host_keys[i]) {
550 key_free(sensitive_data.host_keys[i]);
551 sensitive_data.host_keys[i] = NULL;
554 sensitive_data.ssh1_host_key = NULL;
555 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
558 /* Demote private to public keys for network child */
560 demote_sensitive_data(void)
565 if (sensitive_data.server_key) {
566 tmp = key_demote(sensitive_data.server_key);
567 key_free(sensitive_data.server_key);
568 sensitive_data.server_key = tmp;
571 for (i = 0; i < options.num_host_key_files; i++) {
572 if (sensitive_data.host_keys[i]) {
573 tmp = key_demote(sensitive_data.host_keys[i]);
574 key_free(sensitive_data.host_keys[i]);
575 sensitive_data.host_keys[i] = tmp;
576 if (tmp->type == KEY_RSA1)
577 sensitive_data.ssh1_host_key = tmp;
581 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
585 privsep_preauth_child(void)
591 /* Enable challenge-response authentication for privilege separation */
592 privsep_challenge_enable();
595 for (i = 0; i < 256; i++)
596 rnd[i] = arc4random();
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)
629 /* Set up unprivileged child process to deal with network data */
630 pmonitor = monitor_init();
631 /* Store a pointer to the kex for later rekeying */
632 pmonitor->m_pkex = &xxx_kex;
636 fatal("fork of unprivileged child failed");
637 } else if (pid != 0) {
638 debug2("Network child is on pid %ld", (long)pid);
640 close(pmonitor->m_recvfd);
641 pmonitor->m_pid = pid;
642 monitor_child_preauth(authctxt, pmonitor);
643 close(pmonitor->m_sendfd);
646 monitor_sync(pmonitor);
648 /* Wait for the child's exit status */
649 while (waitpid(pid, &status, 0) < 0)
656 close(pmonitor->m_sendfd);
658 /* Demote the child */
659 if (getuid() == 0 || geteuid() == 0)
660 privsep_preauth_child();
661 setproctitle("%s", "[net]");
667 privsep_postauth(Authctxt *authctxt)
672 #ifdef DISABLE_FD_PASSING
675 if (authctxt->pw->pw_uid == 0 || options.use_login) {
677 /* File descriptor passing is broken or root login */
682 /* New socket pair */
683 monitor_reinit(pmonitor);
685 pmonitor->m_pid = fork();
686 if (pmonitor->m_pid == -1)
687 fatal("fork of unprivileged child failed");
688 else if (pmonitor->m_pid != 0) {
689 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
690 close(pmonitor->m_recvfd);
691 buffer_clear(&loginmsg);
692 monitor_child_postauth(pmonitor);
698 close(pmonitor->m_sendfd);
700 /* Demote the private keys to public keys. */
701 demote_sensitive_data();
704 for (i = 0; i < 256; i++)
705 rnd[i] = arc4random();
706 RAND_seed(rnd, sizeof(rnd));
708 /* Drop privileges */
709 do_setusercontext(authctxt->pw);
712 /* It is safe now to apply the key state */
713 monitor_apply_keystate(pmonitor);
716 * Tell the packet layer that authentication was successful, since
717 * this information is not part of the key state.
719 packet_set_authenticated();
723 list_hostkey_types(void)
731 for (i = 0; i < options.num_host_key_files; i++) {
732 Key *key = sensitive_data.host_keys[i];
738 if (buffer_len(&b) > 0)
739 buffer_append(&b, ",", 1);
740 p = key_ssh_name(key);
741 buffer_append(&b, p, strlen(p));
745 buffer_append(&b, "\0", 1);
746 ret = xstrdup(buffer_ptr(&b));
748 debug("list_hostkey_types: %s", ret);
753 get_hostkey_by_type(int type)
757 for (i = 0; i < options.num_host_key_files; i++) {
758 Key *key = sensitive_data.host_keys[i];
759 if (key != NULL && key->type == type)
766 get_hostkey_by_index(int ind)
768 if (ind < 0 || ind >= options.num_host_key_files)
770 return (sensitive_data.host_keys[ind]);
774 get_hostkey_index(Key *key)
778 for (i = 0; i < options.num_host_key_files; i++) {
779 if (key == sensitive_data.host_keys[i])
786 * returns 1 if connection should be dropped, 0 otherwise.
787 * dropping starts at connection #max_startups_begin with a probability
788 * of (max_startups_rate/100). the probability increases linearly until
789 * all connections are dropped for startups > max_startups
792 drop_connection(int startups)
796 if (startups < options.max_startups_begin)
798 if (startups >= options.max_startups)
800 if (options.max_startups_rate == 100)
803 p = 100 - options.max_startups_rate;
804 p *= startups - options.max_startups_begin;
805 p /= options.max_startups - options.max_startups_begin;
806 p += options.max_startups_rate;
807 r = arc4random() % 100;
809 debug("drop_connection: p %d, r %d", p, r);
810 return (r < p) ? 1 : 0;
816 fprintf(stderr, "%s, %s\n",
817 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
819 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
820 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
826 send_rexec_state(int fd, Buffer *conf)
830 debug3("%s: entering fd = %d config len %d", __func__, fd,
834 * Protocol from reexec master to child:
835 * string configuration
836 * u_int ephemeral_key_follows
837 * bignum e (only if ephemeral_key_follows == 1)
843 * string rngseed (only if OpenSSL is not self-seeded)
846 buffer_put_cstring(&m, buffer_ptr(conf));
848 if (sensitive_data.server_key != NULL &&
849 sensitive_data.server_key->type == KEY_RSA1) {
850 buffer_put_int(&m, 1);
851 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
852 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
853 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
854 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
855 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
856 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
858 buffer_put_int(&m, 0);
860 #ifndef OPENSSL_PRNG_ONLY
861 rexec_send_rng_seed(&m);
864 if (ssh_msg_send(fd, 0, &m) == -1)
865 fatal("%s: ssh_msg_send failed", __func__);
869 debug3("%s: done", __func__);
873 recv_rexec_state(int fd, Buffer *conf)
879 debug3("%s: entering fd = %d", __func__, fd);
883 if (ssh_msg_recv(fd, &m) == -1)
884 fatal("%s: ssh_msg_recv failed", __func__);
885 if (buffer_get_char(&m) != 0)
886 fatal("%s: rexec version mismatch", __func__);
888 cp = buffer_get_string(&m, &len);
890 buffer_append(conf, cp, len + 1);
893 if (buffer_get_int(&m)) {
894 if (sensitive_data.server_key != NULL)
895 key_free(sensitive_data.server_key);
896 sensitive_data.server_key = key_new_private(KEY_RSA1);
897 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
898 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
899 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
900 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
901 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
902 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
903 rsa_generate_additional_parameters(
904 sensitive_data.server_key->rsa);
907 #ifndef OPENSSL_PRNG_ONLY
908 rexec_recv_rng_seed(&m);
913 debug3("%s: done", __func__);
916 /* Accept a connection from inetd */
918 server_accept_inetd(int *sock_in, int *sock_out)
924 close(REEXEC_CONFIG_PASS_FD);
925 *sock_in = *sock_out = dup(STDIN_FILENO);
927 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
928 close(REEXEC_STARTUP_PIPE_FD);
931 *sock_in = dup(STDIN_FILENO);
932 *sock_out = dup(STDOUT_FILENO);
935 * We intentionally do not close the descriptors 0, 1, and 2
936 * as our code for setting the descriptors won't work if
937 * ttyfd happens to be one of those.
939 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
940 dup2(fd, STDIN_FILENO);
941 dup2(fd, STDOUT_FILENO);
942 if (fd > STDOUT_FILENO)
945 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
949 * Listen for TCP connections
954 int ret, listen_sock, on = 1;
956 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
958 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
959 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
961 if (num_listen_socks >= MAX_LISTEN_SOCKS)
962 fatal("Too many listen sockets. "
963 "Enlarge MAX_LISTEN_SOCKS");
964 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
965 ntop, sizeof(ntop), strport, sizeof(strport),
966 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
967 error("getnameinfo failed: %.100s",
968 ssh_gai_strerror(ret));
971 /* Create socket for listening. */
972 listen_sock = socket(ai->ai_family, ai->ai_socktype,
974 if (listen_sock < 0) {
975 /* kernel may not support ipv6 */
976 verbose("socket: %.100s", strerror(errno));
979 if (set_nonblock(listen_sock) == -1) {
984 * Set socket options.
985 * Allow local port reuse in TIME_WAIT.
987 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
988 &on, sizeof(on)) == -1)
989 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
992 /* Only communicate in IPv6 over AF_INET6 sockets. */
993 if (ai->ai_family == AF_INET6) {
994 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY,
995 &on, sizeof(on)) == -1)
996 error("setsockopt IPV6_V6ONLY: %s",
1001 debug("Bind to port %s on %s.", strport, ntop);
1003 /* Bind the socket to the desired port. */
1004 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1005 error("Bind to port %s on %s failed: %.200s.",
1006 strport, ntop, strerror(errno));
1010 listen_socks[num_listen_socks] = listen_sock;
1013 /* Start listening on the port. */
1014 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1015 fatal("listen on [%s]:%s: %.100s",
1016 ntop, strport, strerror(errno));
1017 logit("Server listening on %s port %s.", ntop, strport);
1019 freeaddrinfo(options.listen_addrs);
1021 if (!num_listen_socks)
1022 fatal("Cannot bind any address.");
1026 * The main TCP accept loop. Note that, for the non-debug case, returns
1027 * from this function are in a forked subprocess.
1030 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1033 int i, j, ret, maxfd;
1034 int key_used = 0, startups = 0;
1035 int startup_p[2] = { -1 , -1 };
1036 struct sockaddr_storage from;
1040 /* setup fd set for accept */
1043 for (i = 0; i < num_listen_socks; i++)
1044 if (listen_socks[i] > maxfd)
1045 maxfd = listen_socks[i];
1046 /* pipes connected to unauthenticated childs */
1047 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1048 for (i = 0; i < options.max_startups; i++)
1049 startup_pipes[i] = -1;
1052 * Stay listening for connections until the system crashes or
1053 * the daemon is killed with a signal.
1056 if (received_sighup)
1060 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1063 for (i = 0; i < num_listen_socks; i++)
1064 FD_SET(listen_socks[i], fdset);
1065 for (i = 0; i < options.max_startups; i++)
1066 if (startup_pipes[i] != -1)
1067 FD_SET(startup_pipes[i], fdset);
1069 /* Wait in select until there is a connection. */
1070 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1071 if (ret < 0 && errno != EINTR)
1072 error("select: %.100s", strerror(errno));
1073 if (received_sigterm) {
1074 logit("Received signal %d; terminating.",
1075 (int) received_sigterm);
1076 close_listen_socks();
1077 unlink(options.pid_file);
1080 if (key_used && key_do_regen) {
1081 generate_ephemeral_server_key();
1088 for (i = 0; i < options.max_startups; i++)
1089 if (startup_pipes[i] != -1 &&
1090 FD_ISSET(startup_pipes[i], fdset)) {
1092 * the read end of the pipe is ready
1093 * if the child has closed the pipe
1094 * after successful authentication
1095 * or if the child has died
1097 close(startup_pipes[i]);
1098 startup_pipes[i] = -1;
1101 for (i = 0; i < num_listen_socks; i++) {
1102 if (!FD_ISSET(listen_socks[i], fdset))
1104 fromlen = sizeof(from);
1105 *newsock = accept(listen_socks[i],
1106 (struct sockaddr *)&from, &fromlen);
1108 if (errno != EINTR && errno != EWOULDBLOCK)
1109 error("accept: %.100s", strerror(errno));
1112 if (unset_nonblock(*newsock) == -1) {
1116 if (drop_connection(startups) == 1) {
1117 debug("drop connection #%d", startups);
1121 if (pipe(startup_p) == -1) {
1126 if (rexec_flag && socketpair(AF_UNIX,
1127 SOCK_STREAM, 0, config_s) == -1) {
1128 error("reexec socketpair: %s",
1131 close(startup_p[0]);
1132 close(startup_p[1]);
1136 for (j = 0; j < options.max_startups; j++)
1137 if (startup_pipes[j] == -1) {
1138 startup_pipes[j] = startup_p[0];
1139 if (maxfd < startup_p[0])
1140 maxfd = startup_p[0];
1146 * Got connection. Fork a child to handle it, unless
1147 * we are in debugging mode.
1151 * In debugging mode. Close the listening
1152 * socket, and start processing the
1153 * connection without forking.
1155 debug("Server will not fork when running in debugging mode.");
1156 close_listen_socks();
1157 *sock_in = *newsock;
1158 *sock_out = *newsock;
1159 close(startup_p[0]);
1160 close(startup_p[1]);
1164 send_rexec_state(config_s[0],
1172 * Normal production daemon. Fork, and have
1173 * the child process the connection. The
1174 * parent continues listening.
1176 platform_pre_fork();
1177 if ((pid = fork()) == 0) {
1179 * Child. Close the listening and
1180 * max_startup sockets. Start using
1181 * the accepted socket. Reinitialize
1182 * logging (since our pid has changed).
1183 * We break out of the loop to handle
1186 platform_post_fork_child();
1187 startup_pipe = startup_p[1];
1188 close_startup_pipes();
1189 close_listen_socks();
1190 *sock_in = *newsock;
1191 *sock_out = *newsock;
1192 log_init(__progname,
1194 options.log_facility,
1201 /* Parent. Stay in the loop. */
1202 platform_post_fork_parent(pid);
1204 error("fork: %.100s", strerror(errno));
1206 debug("Forked child %ld.", (long)pid);
1208 close(startup_p[1]);
1211 send_rexec_state(config_s[0], &cfg);
1217 * Mark that the key has been used (it
1218 * was "given" to the child).
1220 if ((options.protocol & SSH_PROTO_1) &&
1222 /* Schedule server key regeneration alarm. */
1223 signal(SIGALRM, key_regeneration_alarm);
1224 alarm(options.key_regeneration_time);
1231 * Ensure that our random state differs
1232 * from that of the child
1237 /* child process check (or debug mode) */
1238 if (num_listen_socks < 0)
1245 * Main program for the daemon.
1248 main(int ac, char **av)
1250 extern char *optarg;
1253 int sock_in = -1, sock_out = -1, newsock = -1;
1254 const char *remote_ip;
1257 int config_s[2] = { -1 , -1 };
1261 #ifdef HAVE_SECUREWARE
1262 (void)set_auth_parameters(ac, av);
1264 __progname = ssh_get_progname(av[0]);
1267 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1270 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1271 for (i = 0; i < ac; i++)
1272 saved_argv[i] = xstrdup(av[i]);
1273 saved_argv[i] = NULL;
1275 #ifndef HAVE_SETPROCTITLE
1276 /* Prepare for later setproctitle emulation */
1277 compat_init_setproctitle(ac, av);
1281 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1282 debug("setgroups(): %.200s", strerror(errno));
1284 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1287 /* Initialize configuration options to their default values. */
1288 initialize_server_options(&options);
1290 /* Parse command-line arguments. */
1291 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
1294 options.address_family = AF_INET;
1297 options.address_family = AF_INET6;
1300 config_file_name = optarg;
1303 if (debug_flag == 0) {
1305 options.log_level = SYSLOG_LEVEL_DEBUG1;
1306 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1307 options.log_level++;
1329 options.log_level = SYSLOG_LEVEL_QUIET;
1332 options.server_key_bits = (int)strtonum(optarg, 256,
1336 options.ports_from_cmdline = 1;
1337 if (options.num_ports >= MAX_PORTS) {
1338 fprintf(stderr, "too many ports.\n");
1341 options.ports[options.num_ports++] = a2port(optarg);
1342 if (options.ports[options.num_ports-1] == 0) {
1343 fprintf(stderr, "Bad port number.\n");
1348 if ((options.login_grace_time = convtime(optarg)) == -1) {
1349 fprintf(stderr, "Invalid login grace time.\n");
1354 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1355 fprintf(stderr, "Invalid key regeneration interval.\n");
1360 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1361 fprintf(stderr, "too many host keys.\n");
1364 options.host_key_files[options.num_host_key_files++] = optarg;
1370 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1371 if (utmp_len > MAXHOSTNAMELEN) {
1372 fprintf(stderr, "Invalid utmp length.\n");
1377 line = xstrdup(optarg);
1378 if (process_server_config_line(&options, line,
1379 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1389 if (rexeced_flag || inetd_flag)
1391 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1392 fatal("sshd re-exec requires execution with an absolute path");
1394 closefrom(REEXEC_MIN_FREE_FD);
1396 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1398 SSLeay_add_all_algorithms();
1401 * Force logging to stderr until we have loaded the private host
1402 * key (unless started from inetd)
1404 log_init(__progname,
1405 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1406 SYSLOG_LEVEL_INFO : options.log_level,
1407 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1408 SYSLOG_FACILITY_AUTH : options.log_facility,
1409 log_stderr || !inetd_flag);
1412 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1413 * root's environment
1415 if (getenv("KRB5CCNAME") != NULL)
1416 unsetenv("KRB5CCNAME");
1419 /* Cray can define user privs drop all privs now!
1420 * Not needed on PRIV_SU systems!
1425 sensitive_data.server_key = NULL;
1426 sensitive_data.ssh1_host_key = NULL;
1427 sensitive_data.have_ssh1_key = 0;
1428 sensitive_data.have_ssh2_key = 0;
1430 /* Fetch our configuration */
1433 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1435 load_server_config(config_file_name, &cfg);
1437 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1438 &cfg, NULL, NULL, NULL);
1442 /* Fill in default values for those options not explicitly set. */
1443 fill_default_server_options(&options);
1445 /* challenge-response is implemented via keyboard interactive */
1446 if (options.challenge_response_authentication)
1447 options.kbd_interactive_authentication = 1;
1449 /* set default channel AF */
1450 channel_set_af(options.address_family);
1452 /* Check that there are no remaining arguments. */
1454 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1458 debug("sshd version %.100s", SSH_RELEASE);
1460 /* Store privilege separation user for later use if required. */
1461 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1462 if (use_privsep || options.kerberos_authentication)
1463 fatal("Privilege separation user %s does not exist",
1466 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1467 privsep_pw = pwcopy(privsep_pw);
1468 xfree(privsep_pw->pw_passwd);
1469 privsep_pw->pw_passwd = xstrdup("*");
1473 /* load private host keys */
1474 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1476 for (i = 0; i < options.num_host_key_files; i++)
1477 sensitive_data.host_keys[i] = NULL;
1479 for (i = 0; i < options.num_host_key_files; i++) {
1480 key = key_load_private(options.host_key_files[i], "", NULL);
1481 if (key && blacklisted_key(key)) {
1483 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
1484 if (options.permit_blacklisted_keys)
1485 error("Host key %s blacklisted (see "
1486 "ssh-vulnkey(1)); continuing anyway", fp);
1488 error("Host key %s blacklisted (see "
1489 "ssh-vulnkey(1))", fp);
1491 if (!options.permit_blacklisted_keys) {
1492 sensitive_data.host_keys[i] = NULL;
1496 sensitive_data.host_keys[i] = key;
1498 error("Could not load host key: %s",
1499 options.host_key_files[i]);
1500 sensitive_data.host_keys[i] = NULL;
1503 switch (key->type) {
1505 sensitive_data.ssh1_host_key = key;
1506 sensitive_data.have_ssh1_key = 1;
1510 sensitive_data.have_ssh2_key = 1;
1513 debug("private host key: #%d type %d %s", i, key->type,
1516 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1517 logit("Disabling protocol version 1. Could not load host key");
1518 options.protocol &= ~SSH_PROTO_1;
1520 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1521 logit("Disabling protocol version 2. Could not load host key");
1522 options.protocol &= ~SSH_PROTO_2;
1524 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1525 logit("sshd: no hostkeys available -- exiting.");
1529 /* Check certain values for sanity. */
1530 if (options.protocol & SSH_PROTO_1) {
1531 if (options.server_key_bits < 512 ||
1532 options.server_key_bits > 32768) {
1533 fprintf(stderr, "Bad server key size.\n");
1537 * Check that server and host key lengths differ sufficiently. This
1538 * is necessary to make double encryption work with rsaref. Oh, I
1539 * hate software patents. I dont know if this can go? Niels
1541 if (options.server_key_bits >
1542 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1543 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1544 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1545 SSH_KEY_BITS_RESERVED) {
1546 options.server_key_bits =
1547 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1548 SSH_KEY_BITS_RESERVED;
1549 debug("Forcing server key to %d bits to make it differ from host key.",
1550 options.server_key_bits);
1557 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1558 (S_ISDIR(st.st_mode) == 0))
1559 fatal("Missing privilege separation directory: %s",
1560 _PATH_PRIVSEP_CHROOT_DIR);
1563 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1564 (st.st_uid != getuid () ||
1565 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1567 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1569 fatal("%s must be owned by root and not group or "
1570 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1573 /* Configuration looks good, so exit if in test mode. */
1578 * Clear out any supplemental groups we may have inherited. This
1579 * prevents inadvertent creation of files with bad modes (in the
1580 * portable version at least, it's certainly possible for PAM
1581 * to create a file, and we can't control the code in every
1582 * module which might be used).
1584 if (setgroups(0, NULL) < 0)
1585 debug("setgroups() failed: %.200s", strerror(errno));
1588 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1589 for (i = 0; i < rexec_argc; i++) {
1590 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1591 rexec_argv[i] = saved_argv[i];
1593 rexec_argv[rexec_argc] = "-R";
1594 rexec_argv[rexec_argc + 1] = NULL;
1597 /* Initialize the log (it is reinitialized below in case we forked). */
1598 if (debug_flag && (!inetd_flag || rexeced_flag))
1600 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1603 * If not in debugging mode, and not started from inetd, disconnect
1604 * from the controlling terminal, and fork. The original process
1607 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1610 #endif /* TIOCNOTTY */
1611 if (daemon(0, 0) < 0)
1612 fatal("daemon() failed: %.200s", strerror(errno));
1614 /* Disconnect from the controlling tty. */
1616 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1618 (void) ioctl(fd, TIOCNOTTY, NULL);
1621 #endif /* TIOCNOTTY */
1623 /* Reinitialize the log (because of the fork above). */
1624 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1626 /* Initialize the random number generator. */
1629 /* Chdir to the root directory so that the current disk can be
1630 unmounted if desired. */
1633 /* ignore SIGPIPE */
1634 signal(SIGPIPE, SIG_IGN);
1636 /* Get a connection, either from inetd or a listening TCP socket */
1638 server_accept_inetd(&sock_in, &sock_out);
1642 if (options.protocol & SSH_PROTO_1)
1643 generate_ephemeral_server_key();
1645 signal(SIGHUP, sighup_handler);
1646 signal(SIGCHLD, main_sigchld_handler);
1647 signal(SIGTERM, sigterm_handler);
1648 signal(SIGQUIT, sigterm_handler);
1651 * Write out the pid file after the sigterm handler
1652 * is setup and the listen sockets are bound
1655 FILE *f = fopen(options.pid_file, "w");
1658 error("Couldn't create pid file \"%s\": %s",
1659 options.pid_file, strerror(errno));
1661 fprintf(f, "%ld\n", (long) getpid());
1666 /* Accept a connection and return in a forked child */
1667 server_accept_loop(&sock_in, &sock_out,
1668 &newsock, config_s);
1671 /* This is the child processing a new connection. */
1672 setproctitle("%s", "[accepted]");
1675 * Initialize the resolver. This may not happen automatically
1676 * before privsep chroot().
1678 if ((_res.options & RES_INIT) == 0) {
1679 debug("res_init()");
1684 * Create a new session and process group since the 4.4BSD
1685 * setlogin() affects the entire process group. We don't
1686 * want the child to be able to affect the parent.
1688 #if !defined(SSHD_ACQUIRES_CTTY)
1690 * If setsid is called, on some platforms sshd will later acquire a
1691 * controlling terminal which will result in "could not set
1692 * controlling tty" errors.
1694 if (!debug_flag && !inetd_flag && setsid() < 0)
1695 error("setsid: %.100s", strerror(errno));
1701 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1702 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1703 dup2(newsock, STDIN_FILENO);
1704 dup2(STDIN_FILENO, STDOUT_FILENO);
1705 if (startup_pipe == -1)
1706 close(REEXEC_STARTUP_PIPE_FD);
1708 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1710 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1712 if (startup_pipe != -1)
1713 close(startup_pipe);
1715 execv(rexec_argv[0], rexec_argv);
1717 /* Reexec has failed, fall back and continue */
1718 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1719 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1720 log_init(__progname, options.log_level,
1721 options.log_facility, log_stderr);
1724 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1726 close(REEXEC_CONFIG_PASS_FD);
1727 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1728 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1729 dup2(fd, STDIN_FILENO);
1730 dup2(fd, STDOUT_FILENO);
1731 if (fd > STDERR_FILENO)
1734 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1735 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1739 * Disable the key regeneration alarm. We will not regenerate the
1740 * key since we are no longer in a position to give it to anyone. We
1741 * will not restart on SIGHUP since it no longer makes sense.
1744 signal(SIGALRM, SIG_DFL);
1745 signal(SIGHUP, SIG_DFL);
1746 signal(SIGTERM, SIG_DFL);
1747 signal(SIGQUIT, SIG_DFL);
1748 signal(SIGCHLD, SIG_DFL);
1749 signal(SIGINT, SIG_DFL);
1752 * Register our connection. This turns encryption off because we do
1755 packet_set_connection(sock_in, sock_out);
1756 packet_set_server();
1758 /* Set SO_KEEPALIVE if requested. */
1759 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1760 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1761 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1763 if ((remote_port = get_remote_port()) < 0) {
1764 debug("get_remote_port failed");
1769 * We use get_canonical_hostname with usedns = 0 instead of
1770 * get_remote_ipaddr here so IP options will be checked.
1772 (void) get_canonical_hostname(0);
1774 * The rest of the code depends on the fact that
1775 * get_remote_ipaddr() caches the remote ip, even if
1776 * the socket goes away.
1778 remote_ip = get_remote_ipaddr();
1780 #ifdef SSH_AUDIT_EVENTS
1781 audit_connection_from(remote_ip, remote_port);
1784 allow_severity = options.log_facility|LOG_INFO;
1785 deny_severity = options.log_facility|LOG_WARNING;
1786 /* Check whether logins are denied from this host. */
1787 if (packet_connection_is_on_socket()) {
1788 struct request_info req;
1790 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1793 if (!hosts_access(&req)) {
1794 debug("Connection refused by tcp wrapper");
1797 fatal("libwrap refuse returns");
1800 #endif /* LIBWRAP */
1802 /* Log the connection. */
1803 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1806 * We don't want to listen forever unless the other side
1807 * successfully authenticates itself. So we set up an alarm which is
1808 * cleared after successful authentication. A limit of zero
1809 * indicates no limit. Note that we don't set the alarm in debugging
1810 * mode; it is just annoying to have the server exit just when you
1811 * are about to discover the bug.
1813 signal(SIGALRM, grace_alarm_handler);
1815 alarm(options.login_grace_time);
1817 sshd_exchange_identification(sock_in, sock_out);
1819 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1820 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1821 generate_ephemeral_server_key();
1823 packet_set_nonblocking();
1825 /* allocate authentication context */
1826 authctxt = xcalloc(1, sizeof(*authctxt));
1828 authctxt->loginmsg = &loginmsg;
1830 /* XXX global for cleanup, access from other modules */
1831 the_authctxt = authctxt;
1833 /* prepare buffer to collect messages to display to user after login */
1834 buffer_init(&loginmsg);
1837 if (privsep_preauth(authctxt) == 1)
1840 /* perform the key exchange */
1841 /* authenticate user and start session */
1844 do_authentication2(authctxt);
1847 do_authentication(authctxt);
1850 * If we use privilege separation, the unprivileged child transfers
1851 * the current keystate and exits
1854 mm_send_keystate(pmonitor);
1860 * Cancel the alarm we set to limit the time taken for
1864 signal(SIGALRM, SIG_DFL);
1865 authctxt->authenticated = 1;
1866 if (startup_pipe != -1) {
1867 close(startup_pipe);
1871 #ifdef SSH_AUDIT_EVENTS
1872 audit_event(SSH_AUTH_SUCCESS);
1876 if (options.gss_authentication) {
1877 temporarily_use_uid(authctxt->pw);
1878 ssh_gssapi_storecreds();
1883 if (options.use_pam) {
1890 * In privilege separation, we fork another child and prepare
1891 * file descriptor passing.
1894 privsep_postauth(authctxt);
1895 /* the monitor process [priv] will not return */
1897 destroy_sensitive_data();
1900 /* Start session. */
1901 do_authenticated(authctxt);
1903 /* The connection has been terminated. */
1904 verbose("Closing connection to %.100s", remote_ip);
1907 if (options.use_pam)
1909 #endif /* USE_PAM */
1911 #ifdef SSH_AUDIT_EVENTS
1912 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1924 * Decrypt session_key_int using our private server key and private host key
1925 * (key with larger modulus first).
1928 ssh1_session_key(BIGNUM *session_key_int)
1932 if (BN_cmp(sensitive_data.server_key->rsa->n,
1933 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1934 /* Server key has bigger modulus. */
1935 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1936 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1937 SSH_KEY_BITS_RESERVED) {
1938 fatal("do_connection: %s: "
1939 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1940 get_remote_ipaddr(),
1941 BN_num_bits(sensitive_data.server_key->rsa->n),
1942 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1943 SSH_KEY_BITS_RESERVED);
1945 if (rsa_private_decrypt(session_key_int, session_key_int,
1946 sensitive_data.server_key->rsa) <= 0)
1948 if (rsa_private_decrypt(session_key_int, session_key_int,
1949 sensitive_data.ssh1_host_key->rsa) <= 0)
1952 /* Host key has bigger modulus (or they are equal). */
1953 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1954 BN_num_bits(sensitive_data.server_key->rsa->n) +
1955 SSH_KEY_BITS_RESERVED) {
1956 fatal("do_connection: %s: "
1957 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1958 get_remote_ipaddr(),
1959 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1960 BN_num_bits(sensitive_data.server_key->rsa->n),
1961 SSH_KEY_BITS_RESERVED);
1963 if (rsa_private_decrypt(session_key_int, session_key_int,
1964 sensitive_data.ssh1_host_key->rsa) < 0)
1966 if (rsa_private_decrypt(session_key_int, session_key_int,
1967 sensitive_data.server_key->rsa) < 0)
1980 BIGNUM *session_key_int;
1981 u_char session_key[SSH_SESSION_KEY_LENGTH];
1983 u_int cipher_type, auth_mask, protocol_flags;
1987 * Generate check bytes that the client must send back in the user
1988 * packet in order for it to be accepted; this is used to defy ip
1989 * spoofing attacks. Note that this only works against somebody
1990 * doing IP spoofing from a remote machine; any machine on the local
1991 * network can still see outgoing packets and catch the random
1992 * cookie. This only affects rhosts authentication, and this is one
1993 * of the reasons why it is inherently insecure.
1995 for (i = 0; i < 8; i++) {
1998 cookie[i] = rnd & 0xff;
2003 * Send our public key. We include in the packet 64 bits of random
2004 * data that must be matched in the reply in order to prevent IP
2007 packet_start(SSH_SMSG_PUBLIC_KEY);
2008 for (i = 0; i < 8; i++)
2009 packet_put_char(cookie[i]);
2011 /* Store our public server RSA key. */
2012 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2013 packet_put_bignum(sensitive_data.server_key->rsa->e);
2014 packet_put_bignum(sensitive_data.server_key->rsa->n);
2016 /* Store our public host RSA key. */
2017 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2018 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2019 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2021 /* Put protocol flags. */
2022 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2024 /* Declare which ciphers we support. */
2025 packet_put_int(cipher_mask_ssh1(0));
2027 /* Declare supported authentication types. */
2029 if (options.rhosts_rsa_authentication)
2030 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2031 if (options.rsa_authentication)
2032 auth_mask |= 1 << SSH_AUTH_RSA;
2033 if (options.challenge_response_authentication == 1)
2034 auth_mask |= 1 << SSH_AUTH_TIS;
2035 if (options.password_authentication)
2036 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2037 packet_put_int(auth_mask);
2039 /* Send the packet and wait for it to be sent. */
2041 packet_write_wait();
2043 debug("Sent %d bit server key and %d bit host key.",
2044 BN_num_bits(sensitive_data.server_key->rsa->n),
2045 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2047 /* Read clients reply (cipher type and session key). */
2048 packet_read_expect(SSH_CMSG_SESSION_KEY);
2050 /* Get cipher type and check whether we accept this. */
2051 cipher_type = packet_get_char();
2053 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2054 packet_disconnect("Warning: client selects unsupported cipher.");
2056 /* Get check bytes from the packet. These must match those we
2057 sent earlier with the public key packet. */
2058 for (i = 0; i < 8; i++)
2059 if (cookie[i] != packet_get_char())
2060 packet_disconnect("IP Spoofing check bytes do not match.");
2062 debug("Encryption type: %.200s", cipher_name(cipher_type));
2064 /* Get the encrypted integer. */
2065 if ((session_key_int = BN_new()) == NULL)
2066 fatal("do_ssh1_kex: BN_new failed");
2067 packet_get_bignum(session_key_int);
2069 protocol_flags = packet_get_int();
2070 packet_set_protocol_flags(protocol_flags);
2073 /* Decrypt session_key_int using host/server keys */
2074 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2077 * Extract session key from the decrypted integer. The key is in the
2078 * least significant 256 bits of the integer; the first byte of the
2079 * key is in the highest bits.
2082 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2083 len = BN_num_bytes(session_key_int);
2084 if (len < 0 || (u_int)len > sizeof(session_key)) {
2085 error("do_ssh1_kex: bad session key len from %s: "
2086 "session_key_int %d > sizeof(session_key) %lu",
2087 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2090 memset(session_key, 0, sizeof(session_key));
2091 BN_bn2bin(session_key_int,
2092 session_key + sizeof(session_key) - len);
2094 derive_ssh1_session_id(
2095 sensitive_data.ssh1_host_key->rsa->n,
2096 sensitive_data.server_key->rsa->n,
2097 cookie, session_id);
2099 * Xor the first 16 bytes of the session key with the
2102 for (i = 0; i < 16; i++)
2103 session_key[i] ^= session_id[i];
2107 int bytes = BN_num_bytes(session_key_int);
2108 u_char *buf = xmalloc(bytes);
2111 logit("do_connection: generating a fake encryption key");
2112 BN_bn2bin(session_key_int, buf);
2114 MD5_Update(&md, buf, bytes);
2115 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2116 MD5_Final(session_key, &md);
2118 MD5_Update(&md, session_key, 16);
2119 MD5_Update(&md, buf, bytes);
2120 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2121 MD5_Final(session_key + 16, &md);
2122 memset(buf, 0, bytes);
2124 for (i = 0; i < 16; i++)
2125 session_id[i] = session_key[i] ^ session_key[i + 16];
2127 /* Destroy the private and public keys. No longer. */
2128 destroy_sensitive_data();
2131 mm_ssh1_session_id(session_id);
2133 /* Destroy the decrypted integer. It is no longer needed. */
2134 BN_clear_free(session_key_int);
2136 /* Set the session key. From this on all communications will be encrypted. */
2137 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2139 /* Destroy our copy of the session key. It is no longer needed. */
2140 memset(session_key, 0, sizeof(session_key));
2142 debug("Received session key; encryption turned on.");
2144 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2145 packet_start(SSH_SMSG_SUCCESS);
2147 packet_write_wait();
2151 * SSH2 key exchange: diffie-hellman-group1-sha1
2158 if (options.ciphers != NULL) {
2159 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2160 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2162 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2163 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2164 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2165 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2167 if (options.macs != NULL) {
2168 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2169 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2171 if (options.compression == COMP_NONE) {
2172 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2173 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2174 } else if (options.compression == COMP_DELAYED) {
2175 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2176 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2179 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2181 /* start key exchange */
2182 kex = kex_setup(myproposal);
2183 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2184 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2185 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2186 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2188 kex->client_version_string=client_version_string;
2189 kex->server_version_string=server_version_string;
2190 kex->load_host_key=&get_hostkey_by_type;
2191 kex->host_key_index=&get_hostkey_index;
2195 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2197 session_id2 = kex->session_id;
2198 session_id2_len = kex->session_id_len;
2201 /* send 1st encrypted/maced/compressed message */
2202 packet_start(SSH2_MSG_IGNORE);
2203 packet_put_cstring("markus");
2205 packet_write_wait();
2210 /* server specific fatal cleanup */
2215 do_cleanup(the_authctxt);
2216 #ifdef SSH_AUDIT_EVENTS
2217 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2218 if (!use_privsep || mm_is_monitor())
2219 audit_event(SSH_CONNECTION_ABANDON);