1 /* $OpenBSD: sshd.c,v 1.348 2006/11/06 21:25:28 markus 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.
48 #include <sys/types.h>
49 #include <sys/ioctl.h>
50 #include <sys/socket.h>
51 #ifdef HAVE_SYS_STAT_H
52 # include <sys/stat.h>
54 #ifdef HAVE_SYS_TIME_H
55 # include <sys/time.h>
57 #include "openbsd-compat/sys-tree.h"
75 #include <openssl/dh.h>
76 #include <openssl/bn.h>
77 #include <openssl/md5.h>
78 #include <openssl/rand.h>
79 #ifdef HAVE_SECUREWARE
80 #include <sys/security.h>
86 #if defined(GSSAPI) && defined(HAVE_GSSAPI_H)
88 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H)
89 #include <gssapi/gssapi.h>
102 #include "servconf.h"
109 #include "myproposal.h"
110 #include "authfile.h"
111 #include "pathnames.h"
112 #include "atomicio.h"
113 #include "canohost.h"
114 #include "hostfile.h"
118 #include "dispatch.h"
119 #include "channels.h"
121 #include "monitor_mm.h"
126 #include "monitor_wrap.h"
127 #include "monitor_fdpass.h"
133 int allow_severity = LOG_INFO;
134 int deny_severity = LOG_WARNING;
142 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
143 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
144 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
145 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
147 extern char *__progname;
149 /* Server configuration options. */
150 ServerOptions options;
152 /* Name of the server configuration file. */
153 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
156 * Debug mode flag. This can be set on the command line. If debug
157 * mode is enabled, extra debugging output will be sent to the system
158 * log, the daemon will not go to background, and will exit after processing
159 * the first connection.
163 /* Flag indicating that the daemon should only test the configuration and keys. */
166 /* Flag indicating that the daemon is being started from inetd. */
169 /* Flag indicating that sshd should not detach and become a daemon. */
170 int no_daemon_flag = 0;
172 /* debug goes to stderr unless inetd_flag is set */
175 /* Saved arguments to main(). */
180 int rexeced_flag = 0;
186 * The sockets that the server is listening; this is used in the SIGHUP
189 #define MAX_LISTEN_SOCKS 16
190 int listen_socks[MAX_LISTEN_SOCKS];
191 int num_listen_socks = 0;
194 * the client's version string, passed by sshd2 in compat mode. if != NULL,
195 * sshd will skip the version-number exchange
197 char *client_version_string = NULL;
198 char *server_version_string = NULL;
200 /* for rekeying XXX fixme */
204 * Any really sensitive data in the application is contained in this
205 * structure. The idea is that this structure could be locked into memory so
206 * that the pages do not get written into swap. However, there are some
207 * problems. The private key contains BIGNUMs, and we do not (in principle)
208 * have access to the internals of them, and locking just the structure is
209 * not very useful. Currently, memory locking is not implemented.
212 Key *server_key; /* ephemeral server key */
213 Key *ssh1_host_key; /* ssh1 host key */
214 Key **host_keys; /* all private host keys */
217 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
221 * Flag indicating whether the RSA server key needs to be regenerated.
222 * Is set in the SIGALRM handler and cleared when the key is regenerated.
224 static volatile sig_atomic_t key_do_regen = 0;
226 /* This is set to true when a signal is received. */
227 static volatile sig_atomic_t received_sighup = 0;
228 static volatile sig_atomic_t received_sigterm = 0;
230 /* session identifier, used by RSA-auth */
231 u_char session_id[16];
234 u_char *session_id2 = NULL;
235 u_int session_id2_len = 0;
237 /* record remote hostname or ip */
238 u_int utmp_len = MAXHOSTNAMELEN;
240 /* options.max_startup sized array of fd ints */
241 int *startup_pipes = NULL;
242 int startup_pipe; /* in child */
244 /* variables used for privilege separation */
245 int use_privsep = -1;
246 struct monitor *pmonitor = NULL;
248 /* global authentication context */
249 Authctxt *the_authctxt = NULL;
251 /* sshd_config buffer */
254 /* message to be displayed after login */
257 /* Unprivileged user */
258 struct passwd *privsep_pw = NULL;
260 /* Prototypes for various functions defined later in this file. */
261 void destroy_sensitive_data(void);
262 void demote_sensitive_data(void);
264 static void do_ssh1_kex(void);
265 static void do_ssh2_kex(void);
268 * Close all listening sockets
271 close_listen_socks(void)
275 for (i = 0; i < num_listen_socks; i++)
276 close(listen_socks[i]);
277 num_listen_socks = -1;
281 close_startup_pipes(void)
286 for (i = 0; i < options.max_startups; i++)
287 if (startup_pipes[i] != -1)
288 close(startup_pipes[i]);
292 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
293 * the effect is to reread the configuration file (and to regenerate
299 sighup_handler(int sig)
301 int save_errno = errno;
304 signal(SIGHUP, sighup_handler);
309 * Called from the main program after receiving SIGHUP.
310 * Restarts the server.
315 logit("Received SIGHUP; restarting.");
316 close_listen_socks();
317 close_startup_pipes();
318 execv(saved_argv[0], saved_argv);
319 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
325 * Generic signal handler for terminating signals in the master daemon.
329 sigterm_handler(int sig)
331 received_sigterm = sig;
335 * SIGCHLD handler. This is called whenever a child dies. This will then
336 * reap any zombies left by exited children.
340 main_sigchld_handler(int sig)
342 int save_errno = errno;
346 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
347 (pid < 0 && errno == EINTR))
350 signal(SIGCHLD, main_sigchld_handler);
355 * Signal handler for the alarm after the login grace period has expired.
359 grace_alarm_handler(int sig)
361 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
362 kill(pmonitor->m_pid, SIGALRM);
364 /* Log error and exit. */
365 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
369 * Signal handler for the key regeneration alarm. Note that this
370 * alarm only occurs in the daemon waiting for connections, and it does not
371 * do anything with the private key or random state before forking.
372 * Thus there should be no concurrency control/asynchronous execution
376 generate_ephemeral_server_key(void)
381 verbose("Generating %s%d bit RSA key.",
382 sensitive_data.server_key ? "new " : "", options.server_key_bits);
383 if (sensitive_data.server_key != NULL)
384 key_free(sensitive_data.server_key);
385 sensitive_data.server_key = key_generate(KEY_RSA1,
386 options.server_key_bits);
387 verbose("RSA key generation complete.");
389 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
392 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
400 key_regeneration_alarm(int sig)
402 int save_errno = errno;
404 signal(SIGALRM, SIG_DFL);
410 sshd_exchange_identification(int sock_in, int sock_out)
414 int remote_major, remote_minor;
417 char buf[256]; /* Must not be larger than remote_version. */
418 char remote_version[256]; /* Must be at least as big as buf. */
420 if ((options.protocol & SSH_PROTO_1) &&
421 (options.protocol & SSH_PROTO_2)) {
422 major = PROTOCOL_MAJOR_1;
424 } else if (options.protocol & SSH_PROTO_2) {
425 major = PROTOCOL_MAJOR_2;
426 minor = PROTOCOL_MINOR_2;
428 major = PROTOCOL_MAJOR_1;
429 minor = PROTOCOL_MINOR_1;
431 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
432 server_version_string = xstrdup(buf);
434 /* Send our protocol version identification. */
435 if (atomicio(vwrite, sock_out, server_version_string,
436 strlen(server_version_string))
437 != strlen(server_version_string)) {
438 logit("Could not write ident string to %s", get_remote_ipaddr());
442 /* Read other sides version identification. */
443 memset(buf, 0, sizeof(buf));
444 for (i = 0; i < sizeof(buf) - 1; i++) {
445 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
446 logit("Did not receive identification string from %s",
447 get_remote_ipaddr());
450 if (buf[i] == '\r') {
452 /* Kludge for F-Secure Macintosh < 1.0.2 */
454 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
458 if (buf[i] == '\n') {
463 buf[sizeof(buf) - 1] = 0;
464 client_version_string = xstrdup(buf);
467 * Check that the versions match. In future this might accept
468 * several versions and set appropriate flags to handle them.
470 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
471 &remote_major, &remote_minor, remote_version) != 3) {
472 s = "Protocol mismatch.\n";
473 (void) atomicio(vwrite, sock_out, s, strlen(s));
476 logit("Bad protocol version identification '%.100s' from %s",
477 client_version_string, get_remote_ipaddr());
480 debug("Client protocol version %d.%d; client software version %.100s",
481 remote_major, remote_minor, remote_version);
483 compat_datafellows(remote_version);
485 if (datafellows & SSH_BUG_PROBE) {
486 logit("probed from %s with %s. Don't panic.",
487 get_remote_ipaddr(), client_version_string);
491 if (datafellows & SSH_BUG_SCANNER) {
492 logit("scanned from %s with %s. Don't panic.",
493 get_remote_ipaddr(), client_version_string);
498 switch (remote_major) {
500 if (remote_minor == 99) {
501 if (options.protocol & SSH_PROTO_2)
507 if (!(options.protocol & SSH_PROTO_1)) {
511 if (remote_minor < 3) {
512 packet_disconnect("Your ssh version is too old and "
513 "is no longer supported. Please install a newer version.");
514 } else if (remote_minor == 3) {
515 /* note that this disables agent-forwarding */
520 if (options.protocol & SSH_PROTO_2) {
529 chop(server_version_string);
530 debug("Local version string %.200s", server_version_string);
533 s = "Protocol major versions differ.\n";
534 (void) atomicio(vwrite, sock_out, s, strlen(s));
537 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
539 server_version_string, client_version_string);
544 /* Destroy the host and server keys. They will no longer be needed. */
546 destroy_sensitive_data(void)
550 if (sensitive_data.server_key) {
551 key_free(sensitive_data.server_key);
552 sensitive_data.server_key = NULL;
554 for (i = 0; i < options.num_host_key_files; i++) {
555 if (sensitive_data.host_keys[i]) {
556 key_free(sensitive_data.host_keys[i]);
557 sensitive_data.host_keys[i] = NULL;
560 sensitive_data.ssh1_host_key = NULL;
561 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
564 /* Demote private to public keys for network child */
566 demote_sensitive_data(void)
571 if (sensitive_data.server_key) {
572 tmp = key_demote(sensitive_data.server_key);
573 key_free(sensitive_data.server_key);
574 sensitive_data.server_key = tmp;
577 for (i = 0; i < options.num_host_key_files; i++) {
578 if (sensitive_data.host_keys[i]) {
579 tmp = key_demote(sensitive_data.host_keys[i]);
580 key_free(sensitive_data.host_keys[i]);
581 sensitive_data.host_keys[i] = tmp;
582 if (tmp->type == KEY_RSA1)
583 sensitive_data.ssh1_host_key = tmp;
587 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
591 privsep_preauth_child(void)
597 /* Enable challenge-response authentication for privilege separation */
598 privsep_challenge_enable();
600 for (i = 0; i < 256; i++)
601 rnd[i] = arc4random();
602 RAND_seed(rnd, sizeof(rnd));
604 /* Demote the private keys to public keys. */
605 demote_sensitive_data();
607 /* Change our root directory */
608 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
609 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
611 if (chdir("/") == -1)
612 fatal("chdir(\"/\"): %s", strerror(errno));
614 /* Drop our privileges */
615 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
616 (u_int)privsep_pw->pw_gid);
618 /* XXX not ready, too heavy after chroot */
619 do_setusercontext(privsep_pw);
621 gidset[0] = privsep_pw->pw_gid;
622 if (setgroups(1, gidset) < 0)
623 fatal("setgroups: %.100s", strerror(errno));
624 permanently_set_uid(privsep_pw);
629 privsep_preauth(Authctxt *authctxt)
634 /* Set up unprivileged child process to deal with network data */
635 pmonitor = monitor_init();
636 /* Store a pointer to the kex for later rekeying */
637 pmonitor->m_pkex = &xxx_kex;
641 fatal("fork of unprivileged child failed");
642 } else if (pid != 0) {
643 debug2("Network child is on pid %ld", (long)pid);
645 close(pmonitor->m_recvfd);
646 pmonitor->m_pid = pid;
647 monitor_child_preauth(authctxt, pmonitor);
648 close(pmonitor->m_sendfd);
651 monitor_sync(pmonitor);
653 /* Wait for the child's exit status */
654 while (waitpid(pid, &status, 0) < 0)
661 close(pmonitor->m_sendfd);
663 /* Demote the child */
664 if (getuid() == 0 || geteuid() == 0)
665 privsep_preauth_child();
666 setproctitle("%s", "[net]");
672 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 debug2("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();
705 /* Drop privileges */
706 do_setusercontext(authctxt->pw);
709 /* It is safe now to apply the key state */
710 monitor_apply_keystate(pmonitor);
713 * Tell the packet layer that authentication was successful, since
714 * this information is not part of the key state.
716 packet_set_authenticated();
720 list_hostkey_types(void)
728 for (i = 0; i < options.num_host_key_files; i++) {
729 Key *key = sensitive_data.host_keys[i];
735 if (buffer_len(&b) > 0)
736 buffer_append(&b, ",", 1);
737 p = key_ssh_name(key);
738 buffer_append(&b, p, strlen(p));
742 buffer_append(&b, "\0", 1);
743 ret = xstrdup(buffer_ptr(&b));
745 debug("list_hostkey_types: %s", ret);
750 get_hostkey_by_type(int type)
754 for (i = 0; i < options.num_host_key_files; i++) {
755 Key *key = sensitive_data.host_keys[i];
756 if (key != NULL && key->type == type)
763 get_hostkey_by_index(int ind)
765 if (ind < 0 || ind >= options.num_host_key_files)
767 return (sensitive_data.host_keys[ind]);
771 get_hostkey_index(Key *key)
775 for (i = 0; i < options.num_host_key_files; i++) {
776 if (key == sensitive_data.host_keys[i])
783 * returns 1 if connection should be dropped, 0 otherwise.
784 * dropping starts at connection #max_startups_begin with a probability
785 * of (max_startups_rate/100). the probability increases linearly until
786 * all connections are dropped for startups > max_startups
789 drop_connection(int startups)
793 if (startups < options.max_startups_begin)
795 if (startups >= options.max_startups)
797 if (options.max_startups_rate == 100)
800 p = 100 - options.max_startups_rate;
801 p *= startups - options.max_startups_begin;
802 p /= options.max_startups - options.max_startups_begin;
803 p += options.max_startups_rate;
804 r = arc4random() % 100;
806 debug("drop_connection: p %d, r %d", p, r);
807 return (r < p) ? 1 : 0;
813 fprintf(stderr, "%s, %s\n",
814 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
816 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
817 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
823 send_rexec_state(int fd, Buffer *conf)
827 debug3("%s: entering fd = %d config len %d", __func__, fd,
831 * Protocol from reexec master to child:
832 * string configuration
833 * u_int ephemeral_key_follows
834 * bignum e (only if ephemeral_key_follows == 1)
840 * string rngseed (only if OpenSSL is not self-seeded)
843 buffer_put_cstring(&m, buffer_ptr(conf));
845 if (sensitive_data.server_key != NULL &&
846 sensitive_data.server_key->type == KEY_RSA1) {
847 buffer_put_int(&m, 1);
848 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
849 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
850 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
851 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
852 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
853 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
855 buffer_put_int(&m, 0);
857 #ifndef OPENSSL_PRNG_ONLY
858 rexec_send_rng_seed(&m);
861 if (ssh_msg_send(fd, 0, &m) == -1)
862 fatal("%s: ssh_msg_send failed", __func__);
866 debug3("%s: done", __func__);
870 recv_rexec_state(int fd, Buffer *conf)
876 debug3("%s: entering fd = %d", __func__, fd);
880 if (ssh_msg_recv(fd, &m) == -1)
881 fatal("%s: ssh_msg_recv failed", __func__);
882 if (buffer_get_char(&m) != 0)
883 fatal("%s: rexec version mismatch", __func__);
885 cp = buffer_get_string(&m, &len);
887 buffer_append(conf, cp, len + 1);
890 if (buffer_get_int(&m)) {
891 if (sensitive_data.server_key != NULL)
892 key_free(sensitive_data.server_key);
893 sensitive_data.server_key = key_new_private(KEY_RSA1);
894 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
895 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
896 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
897 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
898 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
899 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
900 rsa_generate_additional_parameters(
901 sensitive_data.server_key->rsa);
904 #ifndef OPENSSL_PRNG_ONLY
905 rexec_recv_rng_seed(&m);
910 debug3("%s: done", __func__);
913 /* Accept a connection from inetd */
915 server_accept_inetd(int *sock_in, int *sock_out)
921 close(REEXEC_CONFIG_PASS_FD);
922 *sock_in = *sock_out = dup(STDIN_FILENO);
924 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
925 close(REEXEC_STARTUP_PIPE_FD);
928 *sock_in = dup(STDIN_FILENO);
929 *sock_out = dup(STDOUT_FILENO);
932 * We intentionally do not close the descriptors 0, 1, and 2
933 * as our code for setting the descriptors won't work if
934 * ttyfd happens to be one of those.
936 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
937 dup2(fd, STDIN_FILENO);
938 dup2(fd, STDOUT_FILENO);
939 if (fd > STDOUT_FILENO)
942 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
946 * Listen for TCP connections
951 int ret, listen_sock, on = 1;
953 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
955 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
956 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
958 if (num_listen_socks >= MAX_LISTEN_SOCKS)
959 fatal("Too many listen sockets. "
960 "Enlarge MAX_LISTEN_SOCKS");
961 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
962 ntop, sizeof(ntop), strport, sizeof(strport),
963 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
964 error("getnameinfo failed: %.100s",
965 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
969 /* Create socket for listening. */
970 listen_sock = socket(ai->ai_family, ai->ai_socktype,
972 if (listen_sock < 0) {
973 /* kernel may not support ipv6 */
974 verbose("socket: %.100s", strerror(errno));
977 if (set_nonblock(listen_sock) == -1) {
982 * Set socket options.
983 * Allow local port reuse in TIME_WAIT.
985 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
986 &on, sizeof(on)) == -1)
987 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
989 debug("Bind to port %s on %s.", strport, ntop);
991 /* Bind the socket to the desired port. */
992 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
993 error("Bind to port %s on %s failed: %.200s.",
994 strport, ntop, strerror(errno));
998 listen_socks[num_listen_socks] = listen_sock;
1001 /* Start listening on the port. */
1002 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1003 fatal("listen on [%s]:%s: %.100s",
1004 ntop, strport, strerror(errno));
1005 logit("Server listening on %s port %s.", ntop, strport);
1007 freeaddrinfo(options.listen_addrs);
1009 if (!num_listen_socks)
1010 fatal("Cannot bind any address.");
1014 * The main TCP accept loop. Note that, for the non-debug case, returns
1015 * from this function are in a forked subprocess.
1018 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1021 int i, j, ret, maxfd;
1022 int key_used = 0, startups = 0;
1023 int startup_p[2] = { -1 , -1 };
1024 struct sockaddr_storage from;
1028 /* setup fd set for accept */
1031 for (i = 0; i < num_listen_socks; i++)
1032 if (listen_socks[i] > maxfd)
1033 maxfd = listen_socks[i];
1034 /* pipes connected to unauthenticated childs */
1035 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1036 for (i = 0; i < options.max_startups; i++)
1037 startup_pipes[i] = -1;
1040 * Stay listening for connections until the system crashes or
1041 * the daemon is killed with a signal.
1044 if (received_sighup)
1048 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1051 for (i = 0; i < num_listen_socks; i++)
1052 FD_SET(listen_socks[i], fdset);
1053 for (i = 0; i < options.max_startups; i++)
1054 if (startup_pipes[i] != -1)
1055 FD_SET(startup_pipes[i], fdset);
1057 /* Wait in select until there is a connection. */
1058 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1059 if (ret < 0 && errno != EINTR)
1060 error("select: %.100s", strerror(errno));
1061 if (received_sigterm) {
1062 logit("Received signal %d; terminating.",
1063 (int) received_sigterm);
1064 close_listen_socks();
1065 unlink(options.pid_file);
1068 if (key_used && key_do_regen) {
1069 generate_ephemeral_server_key();
1076 for (i = 0; i < options.max_startups; i++)
1077 if (startup_pipes[i] != -1 &&
1078 FD_ISSET(startup_pipes[i], fdset)) {
1080 * the read end of the pipe is ready
1081 * if the child has closed the pipe
1082 * after successful authentication
1083 * or if the child has died
1085 close(startup_pipes[i]);
1086 startup_pipes[i] = -1;
1089 for (i = 0; i < num_listen_socks; i++) {
1090 if (!FD_ISSET(listen_socks[i], fdset))
1092 fromlen = sizeof(from);
1093 *newsock = accept(listen_socks[i],
1094 (struct sockaddr *)&from, &fromlen);
1096 if (errno != EINTR && errno != EWOULDBLOCK)
1097 error("accept: %.100s", strerror(errno));
1100 if (unset_nonblock(*newsock) == -1) {
1104 if (drop_connection(startups) == 1) {
1105 debug("drop connection #%d", startups);
1109 if (pipe(startup_p) == -1) {
1114 if (rexec_flag && socketpair(AF_UNIX,
1115 SOCK_STREAM, 0, config_s) == -1) {
1116 error("reexec socketpair: %s",
1119 close(startup_p[0]);
1120 close(startup_p[1]);
1124 for (j = 0; j < options.max_startups; j++)
1125 if (startup_pipes[j] == -1) {
1126 startup_pipes[j] = startup_p[0];
1127 if (maxfd < startup_p[0])
1128 maxfd = startup_p[0];
1134 * Got connection. Fork a child to handle it, unless
1135 * we are in debugging mode.
1139 * In debugging mode. Close the listening
1140 * socket, and start processing the
1141 * connection without forking.
1143 debug("Server will not fork when running in debugging mode.");
1144 close_listen_socks();
1145 *sock_in = *newsock;
1146 *sock_out = *newsock;
1147 close(startup_p[0]);
1148 close(startup_p[1]);
1152 send_rexec_state(config_s[0],
1160 * Normal production daemon. Fork, and have
1161 * the child process the connection. The
1162 * parent continues listening.
1164 platform_pre_fork();
1165 if ((pid = fork()) == 0) {
1167 * Child. Close the listening and
1168 * max_startup sockets. Start using
1169 * the accepted socket. Reinitialize
1170 * logging (since our pid has changed).
1171 * We break out of the loop to handle
1174 platform_post_fork_child();
1175 startup_pipe = startup_p[1];
1176 close_startup_pipes();
1177 close_listen_socks();
1178 *sock_in = *newsock;
1179 *sock_out = *newsock;
1180 log_init(__progname,
1182 options.log_facility,
1189 /* Parent. Stay in the loop. */
1190 platform_post_fork_parent(pid);
1192 error("fork: %.100s", strerror(errno));
1194 debug("Forked child %ld.", (long)pid);
1196 close(startup_p[1]);
1199 send_rexec_state(config_s[0], &cfg);
1205 * Mark that the key has been used (it
1206 * was "given" to the child).
1208 if ((options.protocol & SSH_PROTO_1) &&
1210 /* Schedule server key regeneration alarm. */
1211 signal(SIGALRM, key_regeneration_alarm);
1212 alarm(options.key_regeneration_time);
1219 * Ensure that our random state differs
1220 * from that of the child
1225 /* child process check (or debug mode) */
1226 if (num_listen_socks < 0)
1233 * Main program for the daemon.
1236 main(int ac, char **av)
1238 extern char *optarg;
1241 int sock_in = -1, sock_out = -1, newsock = -1;
1242 const char *remote_ip;
1245 int config_s[2] = { -1 , -1 };
1249 #ifdef HAVE_SECUREWARE
1250 (void)set_auth_parameters(ac, av);
1252 __progname = ssh_get_progname(av[0]);
1255 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1258 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1259 for (i = 0; i < ac; i++)
1260 saved_argv[i] = xstrdup(av[i]);
1261 saved_argv[i] = NULL;
1263 #ifndef HAVE_SETPROCTITLE
1264 /* Prepare for later setproctitle emulation */
1265 compat_init_setproctitle(ac, av);
1269 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1270 debug("setgroups(): %.200s", strerror(errno));
1272 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1275 /* Initialize configuration options to their default values. */
1276 initialize_server_options(&options);
1278 /* Parse command-line arguments. */
1279 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
1282 options.address_family = AF_INET;
1285 options.address_family = AF_INET6;
1288 config_file_name = optarg;
1291 if (debug_flag == 0) {
1293 options.log_level = SYSLOG_LEVEL_DEBUG1;
1294 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1295 options.log_level++;
1317 options.log_level = SYSLOG_LEVEL_QUIET;
1320 options.server_key_bits = (int)strtonum(optarg, 256,
1324 options.ports_from_cmdline = 1;
1325 if (options.num_ports >= MAX_PORTS) {
1326 fprintf(stderr, "too many ports.\n");
1329 options.ports[options.num_ports++] = a2port(optarg);
1330 if (options.ports[options.num_ports-1] == 0) {
1331 fprintf(stderr, "Bad port number.\n");
1336 if ((options.login_grace_time = convtime(optarg)) == -1) {
1337 fprintf(stderr, "Invalid login grace time.\n");
1342 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1343 fprintf(stderr, "Invalid key regeneration interval.\n");
1348 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1349 fprintf(stderr, "too many host keys.\n");
1352 options.host_key_files[options.num_host_key_files++] = optarg;
1358 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1359 if (utmp_len > MAXHOSTNAMELEN) {
1360 fprintf(stderr, "Invalid utmp length.\n");
1365 line = xstrdup(optarg);
1366 if (process_server_config_line(&options, line,
1367 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1377 if (rexeced_flag || inetd_flag)
1379 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1380 fatal("sshd re-exec requires execution with an absolute path");
1382 closefrom(REEXEC_MIN_FREE_FD);
1384 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1386 SSLeay_add_all_algorithms();
1389 * Force logging to stderr until we have loaded the private host
1390 * key (unless started from inetd)
1392 log_init(__progname,
1393 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1394 SYSLOG_LEVEL_INFO : options.log_level,
1395 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1396 SYSLOG_FACILITY_AUTH : options.log_facility,
1397 log_stderr || !inetd_flag);
1400 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1401 * root's environment
1403 if (getenv("KRB5CCNAME") != NULL)
1404 unsetenv("KRB5CCNAME");
1407 /* Cray can define user privs drop all privs now!
1408 * Not needed on PRIV_SU systems!
1413 sensitive_data.server_key = NULL;
1414 sensitive_data.ssh1_host_key = NULL;
1415 sensitive_data.have_ssh1_key = 0;
1416 sensitive_data.have_ssh2_key = 0;
1418 /* Fetch our configuration */
1421 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1423 load_server_config(config_file_name, &cfg);
1425 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1426 &cfg, NULL, NULL, NULL);
1430 /* Fill in default values for those options not explicitly set. */
1431 fill_default_server_options(&options);
1433 /* set default channel AF */
1434 channel_set_af(options.address_family);
1436 /* Check that there are no remaining arguments. */
1438 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1442 debug("sshd version %.100s", SSH_RELEASE);
1444 /* Store privilege separation user for later use if required. */
1445 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1446 if (use_privsep || options.kerberos_authentication)
1447 fatal("Privilege separation user %s does not exist",
1450 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1451 privsep_pw = pwcopy(privsep_pw);
1452 xfree(privsep_pw->pw_passwd);
1453 privsep_pw->pw_passwd = xstrdup("*");
1457 /* load private host keys */
1458 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1460 for (i = 0; i < options.num_host_key_files; i++)
1461 sensitive_data.host_keys[i] = NULL;
1463 for (i = 0; i < options.num_host_key_files; i++) {
1464 key = key_load_private(options.host_key_files[i], "", NULL);
1465 sensitive_data.host_keys[i] = key;
1467 error("Could not load host key: %s",
1468 options.host_key_files[i]);
1469 sensitive_data.host_keys[i] = NULL;
1472 switch (key->type) {
1474 sensitive_data.ssh1_host_key = key;
1475 sensitive_data.have_ssh1_key = 1;
1479 sensitive_data.have_ssh2_key = 1;
1482 debug("private host key: #%d type %d %s", i, key->type,
1485 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1486 logit("Disabling protocol version 1. Could not load host key");
1487 options.protocol &= ~SSH_PROTO_1;
1489 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1490 logit("Disabling protocol version 2. Could not load host key");
1491 options.protocol &= ~SSH_PROTO_2;
1493 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1494 logit("sshd: no hostkeys available -- exiting.");
1498 /* Check certain values for sanity. */
1499 if (options.protocol & SSH_PROTO_1) {
1500 if (options.server_key_bits < 512 ||
1501 options.server_key_bits > 32768) {
1502 fprintf(stderr, "Bad server key size.\n");
1506 * Check that server and host key lengths differ sufficiently. This
1507 * is necessary to make double encryption work with rsaref. Oh, I
1508 * hate software patents. I dont know if this can go? Niels
1510 if (options.server_key_bits >
1511 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1512 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1513 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1514 SSH_KEY_BITS_RESERVED) {
1515 options.server_key_bits =
1516 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1517 SSH_KEY_BITS_RESERVED;
1518 debug("Forcing server key to %d bits to make it differ from host key.",
1519 options.server_key_bits);
1526 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1527 (S_ISDIR(st.st_mode) == 0))
1528 fatal("Missing privilege separation directory: %s",
1529 _PATH_PRIVSEP_CHROOT_DIR);
1532 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1533 (st.st_uid != getuid () ||
1534 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1536 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1538 fatal("%s must be owned by root and not group or "
1539 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1542 /* Configuration looks good, so exit if in test mode. */
1547 * Clear out any supplemental groups we may have inherited. This
1548 * prevents inadvertent creation of files with bad modes (in the
1549 * portable version at least, it's certainly possible for PAM
1550 * to create a file, and we can't control the code in every
1551 * module which might be used).
1553 if (setgroups(0, NULL) < 0)
1554 debug("setgroups() failed: %.200s", strerror(errno));
1557 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1558 for (i = 0; i < rexec_argc; i++) {
1559 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1560 rexec_argv[i] = saved_argv[i];
1562 rexec_argv[rexec_argc] = "-R";
1563 rexec_argv[rexec_argc + 1] = NULL;
1566 /* Initialize the log (it is reinitialized below in case we forked). */
1567 if (debug_flag && (!inetd_flag || rexeced_flag))
1569 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1572 * If not in debugging mode, and not started from inetd, disconnect
1573 * from the controlling terminal, and fork. The original process
1576 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1579 #endif /* TIOCNOTTY */
1580 if (daemon(0, 0) < 0)
1581 fatal("daemon() failed: %.200s", strerror(errno));
1583 /* Disconnect from the controlling tty. */
1585 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1587 (void) ioctl(fd, TIOCNOTTY, NULL);
1590 #endif /* TIOCNOTTY */
1592 /* Reinitialize the log (because of the fork above). */
1593 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1595 /* Initialize the random number generator. */
1598 /* Chdir to the root directory so that the current disk can be
1599 unmounted if desired. */
1602 /* ignore SIGPIPE */
1603 signal(SIGPIPE, SIG_IGN);
1605 /* Get a connection, either from inetd or a listening TCP socket */
1607 server_accept_inetd(&sock_in, &sock_out);
1609 if ((options.protocol & SSH_PROTO_1) &&
1610 sensitive_data.server_key == NULL)
1611 generate_ephemeral_server_key();
1615 if (options.protocol & SSH_PROTO_1)
1616 generate_ephemeral_server_key();
1618 signal(SIGHUP, sighup_handler);
1619 signal(SIGCHLD, main_sigchld_handler);
1620 signal(SIGTERM, sigterm_handler);
1621 signal(SIGQUIT, sigterm_handler);
1624 * Write out the pid file after the sigterm handler
1625 * is setup and the listen sockets are bound
1628 FILE *f = fopen(options.pid_file, "w");
1631 error("Couldn't create pid file \"%s\": %s",
1632 options.pid_file, strerror(errno));
1634 fprintf(f, "%ld\n", (long) getpid());
1639 /* Accept a connection and return in a forked child */
1640 server_accept_loop(&sock_in, &sock_out,
1641 &newsock, config_s);
1644 /* This is the child processing a new connection. */
1645 setproctitle("%s", "[accepted]");
1648 * Create a new session and process group since the 4.4BSD
1649 * setlogin() affects the entire process group. We don't
1650 * want the child to be able to affect the parent.
1652 #if !defined(SSHD_ACQUIRES_CTTY)
1654 * If setsid is called, on some platforms sshd will later acquire a
1655 * controlling terminal which will result in "could not set
1656 * controlling tty" errors.
1658 if (!debug_flag && !inetd_flag && setsid() < 0)
1659 error("setsid: %.100s", strerror(errno));
1665 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1666 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1667 dup2(newsock, STDIN_FILENO);
1668 dup2(STDIN_FILENO, STDOUT_FILENO);
1669 if (startup_pipe == -1)
1670 close(REEXEC_STARTUP_PIPE_FD);
1672 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1674 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1676 if (startup_pipe != -1)
1677 close(startup_pipe);
1679 execv(rexec_argv[0], rexec_argv);
1681 /* Reexec has failed, fall back and continue */
1682 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1683 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1684 log_init(__progname, options.log_level,
1685 options.log_facility, log_stderr);
1688 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1690 close(REEXEC_CONFIG_PASS_FD);
1691 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1692 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1693 dup2(fd, STDIN_FILENO);
1694 dup2(fd, STDOUT_FILENO);
1695 if (fd > STDERR_FILENO)
1698 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1699 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1703 * Disable the key regeneration alarm. We will not regenerate the
1704 * key since we are no longer in a position to give it to anyone. We
1705 * will not restart on SIGHUP since it no longer makes sense.
1708 signal(SIGALRM, SIG_DFL);
1709 signal(SIGHUP, SIG_DFL);
1710 signal(SIGTERM, SIG_DFL);
1711 signal(SIGQUIT, SIG_DFL);
1712 signal(SIGCHLD, SIG_DFL);
1713 signal(SIGINT, SIG_DFL);
1717 * Initialize the resolver. This may not happen automatically
1718 * before privsep chroot().
1720 if ((_res.options & RES_INIT) == 0) {
1721 debug("res_init()");
1726 * Force GSS-API to parse its configuration and load any
1727 * mechanism plugins.
1731 OM_uint32 minor_status;
1732 gss_indicate_mechs(&minor_status, &mechs);
1733 gss_release_oid_set(&minor_status, &mechs);
1739 * Register our connection. This turns encryption off because we do
1742 packet_set_connection(sock_in, sock_out);
1743 packet_set_server();
1745 /* Set SO_KEEPALIVE if requested. */
1746 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1747 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1748 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1750 if ((remote_port = get_remote_port()) < 0) {
1751 debug("get_remote_port failed");
1756 * We use get_canonical_hostname with usedns = 0 instead of
1757 * get_remote_ipaddr here so IP options will be checked.
1759 (void) get_canonical_hostname(0);
1761 * The rest of the code depends on the fact that
1762 * get_remote_ipaddr() caches the remote ip, even if
1763 * the socket goes away.
1765 remote_ip = get_remote_ipaddr();
1767 #ifdef SSH_AUDIT_EVENTS
1768 audit_connection_from(remote_ip, remote_port);
1771 /* Check whether logins are denied from this host. */
1772 if (packet_connection_is_on_socket()) {
1773 struct request_info req;
1775 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1778 if (!hosts_access(&req)) {
1779 debug("Connection refused by tcp wrapper");
1782 fatal("libwrap refuse returns");
1785 #endif /* LIBWRAP */
1787 /* Log the connection. */
1788 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1791 * We don't want to listen forever unless the other side
1792 * successfully authenticates itself. So we set up an alarm which is
1793 * cleared after successful authentication. A limit of zero
1794 * indicates no limit. Note that we don't set the alarm in debugging
1795 * mode; it is just annoying to have the server exit just when you
1796 * are about to discover the bug.
1798 signal(SIGALRM, grace_alarm_handler);
1800 alarm(options.login_grace_time);
1802 sshd_exchange_identification(sock_in, sock_out);
1804 packet_set_nonblocking();
1806 /* allocate authentication context */
1807 authctxt = xcalloc(1, sizeof(*authctxt));
1809 authctxt->loginmsg = &loginmsg;
1811 /* XXX global for cleanup, access from other modules */
1812 the_authctxt = authctxt;
1814 /* prepare buffer to collect messages to display to user after login */
1815 buffer_init(&loginmsg);
1818 if (privsep_preauth(authctxt) == 1)
1821 /* perform the key exchange */
1822 /* authenticate user and start session */
1825 do_authentication2(authctxt);
1828 do_authentication(authctxt);
1831 * If we use privilege separation, the unprivileged child transfers
1832 * the current keystate and exits
1835 mm_send_keystate(pmonitor);
1841 * Cancel the alarm we set to limit the time taken for
1845 signal(SIGALRM, SIG_DFL);
1846 authctxt->authenticated = 1;
1847 if (startup_pipe != -1) {
1848 close(startup_pipe);
1852 #ifdef SSH_AUDIT_EVENTS
1853 audit_event(SSH_AUTH_SUCCESS);
1857 * In privilege separation, we fork another child and prepare
1858 * file descriptor passing.
1861 privsep_postauth(authctxt);
1862 /* the monitor process [priv] will not return */
1864 destroy_sensitive_data();
1867 /* Start session. */
1868 do_authenticated(authctxt);
1870 /* The connection has been terminated. */
1871 verbose("Closing connection to %.100s", remote_ip);
1874 if (options.use_pam)
1876 #endif /* USE_PAM */
1878 #ifdef SSH_AUDIT_EVENTS
1879 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1891 * Decrypt session_key_int using our private server key and private host key
1892 * (key with larger modulus first).
1895 ssh1_session_key(BIGNUM *session_key_int)
1899 if (BN_cmp(sensitive_data.server_key->rsa->n,
1900 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1901 /* Server key has bigger modulus. */
1902 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1903 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1904 SSH_KEY_BITS_RESERVED) {
1905 fatal("do_connection: %s: "
1906 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1907 get_remote_ipaddr(),
1908 BN_num_bits(sensitive_data.server_key->rsa->n),
1909 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1910 SSH_KEY_BITS_RESERVED);
1912 if (rsa_private_decrypt(session_key_int, session_key_int,
1913 sensitive_data.server_key->rsa) <= 0)
1915 if (rsa_private_decrypt(session_key_int, session_key_int,
1916 sensitive_data.ssh1_host_key->rsa) <= 0)
1919 /* Host key has bigger modulus (or they are equal). */
1920 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1921 BN_num_bits(sensitive_data.server_key->rsa->n) +
1922 SSH_KEY_BITS_RESERVED) {
1923 fatal("do_connection: %s: "
1924 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1925 get_remote_ipaddr(),
1926 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1927 BN_num_bits(sensitive_data.server_key->rsa->n),
1928 SSH_KEY_BITS_RESERVED);
1930 if (rsa_private_decrypt(session_key_int, session_key_int,
1931 sensitive_data.ssh1_host_key->rsa) < 0)
1933 if (rsa_private_decrypt(session_key_int, session_key_int,
1934 sensitive_data.server_key->rsa) < 0)
1947 BIGNUM *session_key_int;
1948 u_char session_key[SSH_SESSION_KEY_LENGTH];
1950 u_int cipher_type, auth_mask, protocol_flags;
1954 * Generate check bytes that the client must send back in the user
1955 * packet in order for it to be accepted; this is used to defy ip
1956 * spoofing attacks. Note that this only works against somebody
1957 * doing IP spoofing from a remote machine; any machine on the local
1958 * network can still see outgoing packets and catch the random
1959 * cookie. This only affects rhosts authentication, and this is one
1960 * of the reasons why it is inherently insecure.
1962 for (i = 0; i < 8; i++) {
1965 cookie[i] = rnd & 0xff;
1970 * Send our public key. We include in the packet 64 bits of random
1971 * data that must be matched in the reply in order to prevent IP
1974 packet_start(SSH_SMSG_PUBLIC_KEY);
1975 for (i = 0; i < 8; i++)
1976 packet_put_char(cookie[i]);
1978 /* Store our public server RSA key. */
1979 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1980 packet_put_bignum(sensitive_data.server_key->rsa->e);
1981 packet_put_bignum(sensitive_data.server_key->rsa->n);
1983 /* Store our public host RSA key. */
1984 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1985 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1986 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1988 /* Put protocol flags. */
1989 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1991 /* Declare which ciphers we support. */
1992 packet_put_int(cipher_mask_ssh1(0));
1994 /* Declare supported authentication types. */
1996 if (options.rhosts_rsa_authentication)
1997 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1998 if (options.rsa_authentication)
1999 auth_mask |= 1 << SSH_AUTH_RSA;
2000 if (options.challenge_response_authentication == 1)
2001 auth_mask |= 1 << SSH_AUTH_TIS;
2002 if (options.password_authentication)
2003 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2004 packet_put_int(auth_mask);
2006 /* Send the packet and wait for it to be sent. */
2008 packet_write_wait();
2010 debug("Sent %d bit server key and %d bit host key.",
2011 BN_num_bits(sensitive_data.server_key->rsa->n),
2012 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2014 /* Read clients reply (cipher type and session key). */
2015 packet_read_expect(SSH_CMSG_SESSION_KEY);
2017 /* Get cipher type and check whether we accept this. */
2018 cipher_type = packet_get_char();
2020 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2021 packet_disconnect("Warning: client selects unsupported cipher.");
2023 /* Get check bytes from the packet. These must match those we
2024 sent earlier with the public key packet. */
2025 for (i = 0; i < 8; i++)
2026 if (cookie[i] != packet_get_char())
2027 packet_disconnect("IP Spoofing check bytes do not match.");
2029 debug("Encryption type: %.200s", cipher_name(cipher_type));
2031 /* Get the encrypted integer. */
2032 if ((session_key_int = BN_new()) == NULL)
2033 fatal("do_ssh1_kex: BN_new failed");
2034 packet_get_bignum(session_key_int);
2036 protocol_flags = packet_get_int();
2037 packet_set_protocol_flags(protocol_flags);
2040 /* Decrypt session_key_int using host/server keys */
2041 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2044 * Extract session key from the decrypted integer. The key is in the
2045 * least significant 256 bits of the integer; the first byte of the
2046 * key is in the highest bits.
2049 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2050 len = BN_num_bytes(session_key_int);
2051 if (len < 0 || (u_int)len > sizeof(session_key)) {
2052 error("do_ssh1_kex: bad session key len from %s: "
2053 "session_key_int %d > sizeof(session_key) %lu",
2054 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2057 memset(session_key, 0, sizeof(session_key));
2058 BN_bn2bin(session_key_int,
2059 session_key + sizeof(session_key) - len);
2061 derive_ssh1_session_id(
2062 sensitive_data.ssh1_host_key->rsa->n,
2063 sensitive_data.server_key->rsa->n,
2064 cookie, session_id);
2066 * Xor the first 16 bytes of the session key with the
2069 for (i = 0; i < 16; i++)
2070 session_key[i] ^= session_id[i];
2074 int bytes = BN_num_bytes(session_key_int);
2075 u_char *buf = xmalloc(bytes);
2078 logit("do_connection: generating a fake encryption key");
2079 BN_bn2bin(session_key_int, buf);
2081 MD5_Update(&md, buf, bytes);
2082 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2083 MD5_Final(session_key, &md);
2085 MD5_Update(&md, session_key, 16);
2086 MD5_Update(&md, buf, bytes);
2087 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2088 MD5_Final(session_key + 16, &md);
2089 memset(buf, 0, bytes);
2091 for (i = 0; i < 16; i++)
2092 session_id[i] = session_key[i] ^ session_key[i + 16];
2094 /* Destroy the private and public keys. No longer. */
2095 destroy_sensitive_data();
2098 mm_ssh1_session_id(session_id);
2100 /* Destroy the decrypted integer. It is no longer needed. */
2101 BN_clear_free(session_key_int);
2103 /* Set the session key. From this on all communications will be encrypted. */
2104 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2106 /* Destroy our copy of the session key. It is no longer needed. */
2107 memset(session_key, 0, sizeof(session_key));
2109 debug("Received session key; encryption turned on.");
2111 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2112 packet_start(SSH_SMSG_SUCCESS);
2114 packet_write_wait();
2118 * SSH2 key exchange: diffie-hellman-group1-sha1
2125 if (options.ciphers != NULL) {
2126 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2127 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2129 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2130 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2131 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2132 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2134 if (options.macs != NULL) {
2135 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2136 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2138 if (options.compression == COMP_NONE) {
2139 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2140 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2141 } else if (options.compression == COMP_DELAYED) {
2142 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2143 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2146 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2148 /* start key exchange */
2149 kex = kex_setup(myproposal);
2150 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2151 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2152 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2153 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2155 kex->client_version_string=client_version_string;
2156 kex->server_version_string=server_version_string;
2157 kex->load_host_key=&get_hostkey_by_type;
2158 kex->host_key_index=&get_hostkey_index;
2162 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2164 session_id2 = kex->session_id;
2165 session_id2_len = kex->session_id_len;
2168 /* send 1st encrypted/maced/compressed message */
2169 packet_start(SSH2_MSG_IGNORE);
2170 packet_put_cstring("markus");
2172 packet_write_wait();
2177 /* server specific fatal cleanup */
2182 do_cleanup(the_authctxt);
2183 #ifdef SSH_AUDIT_EVENTS
2184 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2185 if (!use_privsep || mm_is_monitor())
2186 audit_event(SSH_CONNECTION_ABANDON);