1 /* $OpenBSD: sshd.c,v 1.347 2006/08/18 09:15:20 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.
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"
73 #include <openssl/dh.h>
74 #include <openssl/bn.h>
75 #include <openssl/md5.h>
76 #include <openssl/rand.h>
77 #ifdef HAVE_SECUREWARE
78 #include <sys/security.h>
98 #include "myproposal.h"
100 #include "pathnames.h"
101 #include "atomicio.h"
102 #include "canohost.h"
103 #include "hostfile.h"
107 #include "dispatch.h"
108 #include "channels.h"
110 #include "monitor_mm.h"
115 #include "monitor_wrap.h"
116 #include "monitor_fdpass.h"
122 int allow_severity = LOG_INFO;
123 int deny_severity = LOG_WARNING;
131 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
132 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
133 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
134 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
136 extern char *__progname;
138 /* Server configuration options. */
139 ServerOptions options;
141 /* Name of the server configuration file. */
142 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
145 * Debug mode flag. This can be set on the command line. If debug
146 * mode is enabled, extra debugging output will be sent to the system
147 * log, the daemon will not go to background, and will exit after processing
148 * the first connection.
152 /* Flag indicating that the daemon should only test the configuration and keys. */
155 /* Flag indicating that the daemon is being started from inetd. */
158 /* Flag indicating that sshd should not detach and become a daemon. */
159 int no_daemon_flag = 0;
161 /* debug goes to stderr unless inetd_flag is set */
164 /* Saved arguments to main(). */
169 int rexeced_flag = 0;
175 * The sockets that the server is listening; this is used in the SIGHUP
178 #define MAX_LISTEN_SOCKS 16
179 int listen_socks[MAX_LISTEN_SOCKS];
180 int num_listen_socks = 0;
183 * the client's version string, passed by sshd2 in compat mode. if != NULL,
184 * sshd will skip the version-number exchange
186 char *client_version_string = NULL;
187 char *server_version_string = NULL;
189 /* for rekeying XXX fixme */
193 * Any really sensitive data in the application is contained in this
194 * structure. The idea is that this structure could be locked into memory so
195 * that the pages do not get written into swap. However, there are some
196 * problems. The private key contains BIGNUMs, and we do not (in principle)
197 * have access to the internals of them, and locking just the structure is
198 * not very useful. Currently, memory locking is not implemented.
201 Key *server_key; /* ephemeral server key */
202 Key *ssh1_host_key; /* ssh1 host key */
203 Key **host_keys; /* all private host keys */
206 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
210 * Flag indicating whether the RSA server key needs to be regenerated.
211 * Is set in the SIGALRM handler and cleared when the key is regenerated.
213 static volatile sig_atomic_t key_do_regen = 0;
215 /* This is set to true when a signal is received. */
216 static volatile sig_atomic_t received_sighup = 0;
217 static volatile sig_atomic_t received_sigterm = 0;
219 /* session identifier, used by RSA-auth */
220 u_char session_id[16];
223 u_char *session_id2 = NULL;
224 u_int session_id2_len = 0;
226 /* record remote hostname or ip */
227 u_int utmp_len = MAXHOSTNAMELEN;
229 /* options.max_startup sized array of fd ints */
230 int *startup_pipes = NULL;
231 int startup_pipe; /* in child */
233 /* variables used for privilege separation */
234 int use_privsep = -1;
235 struct monitor *pmonitor = NULL;
237 /* global authentication context */
238 Authctxt *the_authctxt = NULL;
240 /* sshd_config buffer */
243 /* message to be displayed after login */
246 /* Prototypes for various functions defined later in this file. */
247 void destroy_sensitive_data(void);
248 void demote_sensitive_data(void);
250 static void do_ssh1_kex(void);
251 static void do_ssh2_kex(void);
254 * Close all listening sockets
257 close_listen_socks(void)
261 for (i = 0; i < num_listen_socks; i++)
262 close(listen_socks[i]);
263 num_listen_socks = -1;
267 close_startup_pipes(void)
272 for (i = 0; i < options.max_startups; i++)
273 if (startup_pipes[i] != -1)
274 close(startup_pipes[i]);
278 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
279 * the effect is to reread the configuration file (and to regenerate
285 sighup_handler(int sig)
287 int save_errno = errno;
290 signal(SIGHUP, sighup_handler);
295 * Called from the main program after receiving SIGHUP.
296 * Restarts the server.
301 logit("Received SIGHUP; restarting.");
302 close_listen_socks();
303 close_startup_pipes();
304 execv(saved_argv[0], saved_argv);
305 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
311 * Generic signal handler for terminating signals in the master daemon.
315 sigterm_handler(int sig)
317 received_sigterm = sig;
321 * SIGCHLD handler. This is called whenever a child dies. This will then
322 * reap any zombies left by exited children.
326 main_sigchld_handler(int sig)
328 int save_errno = errno;
332 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
333 (pid < 0 && errno == EINTR))
336 signal(SIGCHLD, main_sigchld_handler);
341 * Signal handler for the alarm after the login grace period has expired.
345 grace_alarm_handler(int sig)
347 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
348 kill(pmonitor->m_pid, SIGALRM);
350 /* Log error and exit. */
351 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
355 * Signal handler for the key regeneration alarm. Note that this
356 * alarm only occurs in the daemon waiting for connections, and it does not
357 * do anything with the private key or random state before forking.
358 * Thus there should be no concurrency control/asynchronous execution
362 generate_ephemeral_server_key(void)
367 verbose("Generating %s%d bit RSA key.",
368 sensitive_data.server_key ? "new " : "", options.server_key_bits);
369 if (sensitive_data.server_key != NULL)
370 key_free(sensitive_data.server_key);
371 sensitive_data.server_key = key_generate(KEY_RSA1,
372 options.server_key_bits);
373 verbose("RSA key generation complete.");
375 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
378 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
386 key_regeneration_alarm(int sig)
388 int save_errno = errno;
390 signal(SIGALRM, SIG_DFL);
396 sshd_exchange_identification(int sock_in, int sock_out)
400 int remote_major, remote_minor;
403 char buf[256]; /* Must not be larger than remote_version. */
404 char remote_version[256]; /* Must be at least as big as buf. */
406 if ((options.protocol & SSH_PROTO_1) &&
407 (options.protocol & SSH_PROTO_2)) {
408 major = PROTOCOL_MAJOR_1;
410 } else if (options.protocol & SSH_PROTO_2) {
411 major = PROTOCOL_MAJOR_2;
412 minor = PROTOCOL_MINOR_2;
414 major = PROTOCOL_MAJOR_1;
415 minor = PROTOCOL_MINOR_1;
417 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
418 server_version_string = xstrdup(buf);
420 /* Send our protocol version identification. */
421 if (atomicio(vwrite, sock_out, server_version_string,
422 strlen(server_version_string))
423 != strlen(server_version_string)) {
424 logit("Could not write ident string to %s", get_remote_ipaddr());
428 /* Read other sides version identification. */
429 memset(buf, 0, sizeof(buf));
430 for (i = 0; i < sizeof(buf) - 1; i++) {
431 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
432 logit("Did not receive identification string from %s",
433 get_remote_ipaddr());
436 if (buf[i] == '\r') {
438 /* Kludge for F-Secure Macintosh < 1.0.2 */
440 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
444 if (buf[i] == '\n') {
449 buf[sizeof(buf) - 1] = 0;
450 client_version_string = xstrdup(buf);
453 * Check that the versions match. In future this might accept
454 * several versions and set appropriate flags to handle them.
456 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
457 &remote_major, &remote_minor, remote_version) != 3) {
458 s = "Protocol mismatch.\n";
459 (void) atomicio(vwrite, sock_out, s, strlen(s));
462 logit("Bad protocol version identification '%.100s' from %s",
463 client_version_string, get_remote_ipaddr());
466 debug("Client protocol version %d.%d; client software version %.100s",
467 remote_major, remote_minor, remote_version);
469 compat_datafellows(remote_version);
471 if (datafellows & SSH_BUG_PROBE) {
472 logit("probed from %s with %s. Don't panic.",
473 get_remote_ipaddr(), client_version_string);
477 if (datafellows & SSH_BUG_SCANNER) {
478 logit("scanned from %s with %s. Don't panic.",
479 get_remote_ipaddr(), client_version_string);
484 switch (remote_major) {
486 if (remote_minor == 99) {
487 if (options.protocol & SSH_PROTO_2)
493 if (!(options.protocol & SSH_PROTO_1)) {
497 if (remote_minor < 3) {
498 packet_disconnect("Your ssh version is too old and "
499 "is no longer supported. Please install a newer version.");
500 } else if (remote_minor == 3) {
501 /* note that this disables agent-forwarding */
506 if (options.protocol & SSH_PROTO_2) {
515 chop(server_version_string);
516 debug("Local version string %.200s", server_version_string);
519 s = "Protocol major versions differ.\n";
520 (void) atomicio(vwrite, sock_out, s, strlen(s));
523 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
525 server_version_string, client_version_string);
530 /* Destroy the host and server keys. They will no longer be needed. */
532 destroy_sensitive_data(void)
536 if (sensitive_data.server_key) {
537 key_free(sensitive_data.server_key);
538 sensitive_data.server_key = NULL;
540 for (i = 0; i < options.num_host_key_files; i++) {
541 if (sensitive_data.host_keys[i]) {
542 key_free(sensitive_data.host_keys[i]);
543 sensitive_data.host_keys[i] = NULL;
546 sensitive_data.ssh1_host_key = NULL;
547 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
550 /* Demote private to public keys for network child */
552 demote_sensitive_data(void)
557 if (sensitive_data.server_key) {
558 tmp = key_demote(sensitive_data.server_key);
559 key_free(sensitive_data.server_key);
560 sensitive_data.server_key = tmp;
563 for (i = 0; i < options.num_host_key_files; i++) {
564 if (sensitive_data.host_keys[i]) {
565 tmp = key_demote(sensitive_data.host_keys[i]);
566 key_free(sensitive_data.host_keys[i]);
567 sensitive_data.host_keys[i] = tmp;
568 if (tmp->type == KEY_RSA1)
569 sensitive_data.ssh1_host_key = tmp;
573 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
577 privsep_preauth_child(void)
584 /* Enable challenge-response authentication for privilege separation */
585 privsep_challenge_enable();
587 for (i = 0; i < 256; i++)
588 rnd[i] = arc4random();
589 RAND_seed(rnd, sizeof(rnd));
591 /* Demote the private keys to public keys. */
592 demote_sensitive_data();
594 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
595 fatal("Privilege separation user %s does not exist",
597 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
600 /* Change our root directory */
601 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
602 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
604 if (chdir("/") == -1)
605 fatal("chdir(\"/\"): %s", strerror(errno));
607 /* Drop our privileges */
608 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
611 /* XXX not ready, too heavy after chroot */
612 do_setusercontext(pw);
614 gidset[0] = pw->pw_gid;
615 if (setgroups(1, gidset) < 0)
616 fatal("setgroups: %.100s", strerror(errno));
617 permanently_set_uid(pw);
622 privsep_preauth(Authctxt *authctxt)
627 /* Set up unprivileged child process to deal with network data */
628 pmonitor = monitor_init();
629 /* Store a pointer to the kex for later rekeying */
630 pmonitor->m_pkex = &xxx_kex;
634 fatal("fork of unprivileged child failed");
635 } else if (pid != 0) {
636 debug2("Network child is on pid %ld", (long)pid);
638 close(pmonitor->m_recvfd);
639 pmonitor->m_pid = pid;
640 monitor_child_preauth(authctxt, pmonitor);
641 close(pmonitor->m_sendfd);
644 monitor_sync(pmonitor);
646 /* Wait for the child's exit status */
647 while (waitpid(pid, &status, 0) < 0)
654 close(pmonitor->m_sendfd);
656 /* Demote the child */
657 if (getuid() == 0 || geteuid() == 0)
658 privsep_preauth_child();
659 setproctitle("%s", "[net]");
665 privsep_postauth(Authctxt *authctxt)
667 #ifdef DISABLE_FD_PASSING
670 if (authctxt->pw->pw_uid == 0 || options.use_login) {
672 /* File descriptor passing is broken or root login */
677 /* New socket pair */
678 monitor_reinit(pmonitor);
680 pmonitor->m_pid = fork();
681 if (pmonitor->m_pid == -1)
682 fatal("fork of unprivileged child failed");
683 else if (pmonitor->m_pid != 0) {
684 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
685 close(pmonitor->m_recvfd);
686 buffer_clear(&loginmsg);
687 monitor_child_postauth(pmonitor);
693 close(pmonitor->m_sendfd);
695 /* Demote the private keys to public keys. */
696 demote_sensitive_data();
698 /* Drop privileges */
699 do_setusercontext(authctxt->pw);
702 /* It is safe now to apply the key state */
703 monitor_apply_keystate(pmonitor);
706 * Tell the packet layer that authentication was successful, since
707 * this information is not part of the key state.
709 packet_set_authenticated();
713 list_hostkey_types(void)
721 for (i = 0; i < options.num_host_key_files; i++) {
722 Key *key = sensitive_data.host_keys[i];
728 if (buffer_len(&b) > 0)
729 buffer_append(&b, ",", 1);
730 p = key_ssh_name(key);
731 buffer_append(&b, p, strlen(p));
735 buffer_append(&b, "\0", 1);
736 ret = xstrdup(buffer_ptr(&b));
738 debug("list_hostkey_types: %s", ret);
743 get_hostkey_by_type(int type)
747 for (i = 0; i < options.num_host_key_files; i++) {
748 Key *key = sensitive_data.host_keys[i];
749 if (key != NULL && key->type == type)
756 get_hostkey_by_index(int ind)
758 if (ind < 0 || ind >= options.num_host_key_files)
760 return (sensitive_data.host_keys[ind]);
764 get_hostkey_index(Key *key)
768 for (i = 0; i < options.num_host_key_files; i++) {
769 if (key == sensitive_data.host_keys[i])
776 * returns 1 if connection should be dropped, 0 otherwise.
777 * dropping starts at connection #max_startups_begin with a probability
778 * of (max_startups_rate/100). the probability increases linearly until
779 * all connections are dropped for startups > max_startups
782 drop_connection(int startups)
786 if (startups < options.max_startups_begin)
788 if (startups >= options.max_startups)
790 if (options.max_startups_rate == 100)
793 p = 100 - options.max_startups_rate;
794 p *= startups - options.max_startups_begin;
795 p /= options.max_startups - options.max_startups_begin;
796 p += options.max_startups_rate;
797 r = arc4random() % 100;
799 debug("drop_connection: p %d, r %d", p, r);
800 return (r < p) ? 1 : 0;
806 fprintf(stderr, "%s, %s\n",
807 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
809 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
810 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
816 send_rexec_state(int fd, Buffer *conf)
820 debug3("%s: entering fd = %d config len %d", __func__, fd,
824 * Protocol from reexec master to child:
825 * string configuration
826 * u_int ephemeral_key_follows
827 * bignum e (only if ephemeral_key_follows == 1)
833 * string rngseed (only if OpenSSL is not self-seeded)
836 buffer_put_cstring(&m, buffer_ptr(conf));
838 if (sensitive_data.server_key != NULL &&
839 sensitive_data.server_key->type == KEY_RSA1) {
840 buffer_put_int(&m, 1);
841 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
842 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
843 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
844 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
845 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
846 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
848 buffer_put_int(&m, 0);
850 #ifndef OPENSSL_PRNG_ONLY
851 rexec_send_rng_seed(&m);
854 if (ssh_msg_send(fd, 0, &m) == -1)
855 fatal("%s: ssh_msg_send failed", __func__);
859 debug3("%s: done", __func__);
863 recv_rexec_state(int fd, Buffer *conf)
869 debug3("%s: entering fd = %d", __func__, fd);
873 if (ssh_msg_recv(fd, &m) == -1)
874 fatal("%s: ssh_msg_recv failed", __func__);
875 if (buffer_get_char(&m) != 0)
876 fatal("%s: rexec version mismatch", __func__);
878 cp = buffer_get_string(&m, &len);
880 buffer_append(conf, cp, len + 1);
883 if (buffer_get_int(&m)) {
884 if (sensitive_data.server_key != NULL)
885 key_free(sensitive_data.server_key);
886 sensitive_data.server_key = key_new_private(KEY_RSA1);
887 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
888 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
889 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
890 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
891 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
892 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
893 rsa_generate_additional_parameters(
894 sensitive_data.server_key->rsa);
897 #ifndef OPENSSL_PRNG_ONLY
898 rexec_recv_rng_seed(&m);
903 debug3("%s: done", __func__);
906 /* Accept a connection from inetd */
908 server_accept_inetd(int *sock_in, int *sock_out)
914 close(REEXEC_CONFIG_PASS_FD);
915 *sock_in = *sock_out = dup(STDIN_FILENO);
917 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
918 close(REEXEC_STARTUP_PIPE_FD);
921 *sock_in = dup(STDIN_FILENO);
922 *sock_out = dup(STDOUT_FILENO);
925 * We intentionally do not close the descriptors 0, 1, and 2
926 * as our code for setting the descriptors won't work if
927 * ttyfd happens to be one of those.
929 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
930 dup2(fd, STDIN_FILENO);
931 dup2(fd, STDOUT_FILENO);
932 if (fd > STDOUT_FILENO)
935 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
939 * Listen for TCP connections
944 int ret, listen_sock, on = 1;
946 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
948 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
949 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
951 if (num_listen_socks >= MAX_LISTEN_SOCKS)
952 fatal("Too many listen sockets. "
953 "Enlarge MAX_LISTEN_SOCKS");
954 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
955 ntop, sizeof(ntop), strport, sizeof(strport),
956 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
957 error("getnameinfo failed: %.100s",
958 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
962 /* Create socket for listening. */
963 listen_sock = socket(ai->ai_family, ai->ai_socktype,
965 if (listen_sock < 0) {
966 /* kernel may not support ipv6 */
967 verbose("socket: %.100s", strerror(errno));
970 if (set_nonblock(listen_sock) == -1) {
975 * Set socket options.
976 * Allow local port reuse in TIME_WAIT.
978 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
979 &on, sizeof(on)) == -1)
980 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
982 debug("Bind to port %s on %s.", strport, ntop);
984 /* Bind the socket to the desired port. */
985 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
986 error("Bind to port %s on %s failed: %.200s.",
987 strport, ntop, strerror(errno));
991 listen_socks[num_listen_socks] = listen_sock;
994 /* Start listening on the port. */
995 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
996 fatal("listen on [%s]:%s: %.100s",
997 ntop, strport, strerror(errno));
998 logit("Server listening on %s port %s.", ntop, strport);
1000 freeaddrinfo(options.listen_addrs);
1002 if (!num_listen_socks)
1003 fatal("Cannot bind any address.");
1007 * The main TCP accept loop. Note that, for the non-debug case, returns
1008 * from this function are in a forked subprocess.
1011 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1014 int i, j, ret, maxfd;
1015 int key_used = 0, startups = 0;
1016 int startup_p[2] = { -1 , -1 };
1017 struct sockaddr_storage from;
1021 /* setup fd set for accept */
1024 for (i = 0; i < num_listen_socks; i++)
1025 if (listen_socks[i] > maxfd)
1026 maxfd = listen_socks[i];
1027 /* pipes connected to unauthenticated childs */
1028 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1029 for (i = 0; i < options.max_startups; i++)
1030 startup_pipes[i] = -1;
1033 * Stay listening for connections until the system crashes or
1034 * the daemon is killed with a signal.
1037 if (received_sighup)
1041 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1044 for (i = 0; i < num_listen_socks; i++)
1045 FD_SET(listen_socks[i], fdset);
1046 for (i = 0; i < options.max_startups; i++)
1047 if (startup_pipes[i] != -1)
1048 FD_SET(startup_pipes[i], fdset);
1050 /* Wait in select until there is a connection. */
1051 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1052 if (ret < 0 && errno != EINTR)
1053 error("select: %.100s", strerror(errno));
1054 if (received_sigterm) {
1055 logit("Received signal %d; terminating.",
1056 (int) received_sigterm);
1057 close_listen_socks();
1058 unlink(options.pid_file);
1061 if (key_used && key_do_regen) {
1062 generate_ephemeral_server_key();
1069 for (i = 0; i < options.max_startups; i++)
1070 if (startup_pipes[i] != -1 &&
1071 FD_ISSET(startup_pipes[i], fdset)) {
1073 * the read end of the pipe is ready
1074 * if the child has closed the pipe
1075 * after successful authentication
1076 * or if the child has died
1078 close(startup_pipes[i]);
1079 startup_pipes[i] = -1;
1082 for (i = 0; i < num_listen_socks; i++) {
1083 if (!FD_ISSET(listen_socks[i], fdset))
1085 fromlen = sizeof(from);
1086 *newsock = accept(listen_socks[i],
1087 (struct sockaddr *)&from, &fromlen);
1089 if (errno != EINTR && errno != EWOULDBLOCK)
1090 error("accept: %.100s", strerror(errno));
1093 if (unset_nonblock(*newsock) == -1) {
1097 if (drop_connection(startups) == 1) {
1098 debug("drop connection #%d", startups);
1102 if (pipe(startup_p) == -1) {
1107 if (rexec_flag && socketpair(AF_UNIX,
1108 SOCK_STREAM, 0, config_s) == -1) {
1109 error("reexec socketpair: %s",
1112 close(startup_p[0]);
1113 close(startup_p[1]);
1117 for (j = 0; j < options.max_startups; j++)
1118 if (startup_pipes[j] == -1) {
1119 startup_pipes[j] = startup_p[0];
1120 if (maxfd < startup_p[0])
1121 maxfd = startup_p[0];
1127 * Got connection. Fork a child to handle it, unless
1128 * we are in debugging mode.
1132 * In debugging mode. Close the listening
1133 * socket, and start processing the
1134 * connection without forking.
1136 debug("Server will not fork when running in debugging mode.");
1137 close_listen_socks();
1138 *sock_in = *newsock;
1139 *sock_out = *newsock;
1140 close(startup_p[0]);
1141 close(startup_p[1]);
1145 send_rexec_state(config_s[0],
1153 * Normal production daemon. Fork, and have
1154 * the child process the connection. The
1155 * parent continues listening.
1157 platform_pre_fork();
1158 if ((pid = fork()) == 0) {
1160 * Child. Close the listening and
1161 * max_startup sockets. Start using
1162 * the accepted socket. Reinitialize
1163 * logging (since our pid has changed).
1164 * We break out of the loop to handle
1167 platform_post_fork_child();
1168 startup_pipe = startup_p[1];
1169 close_startup_pipes();
1170 close_listen_socks();
1171 *sock_in = *newsock;
1172 *sock_out = *newsock;
1173 log_init(__progname,
1175 options.log_facility,
1182 /* Parent. Stay in the loop. */
1183 platform_post_fork_parent(pid);
1185 error("fork: %.100s", strerror(errno));
1187 debug("Forked child %ld.", (long)pid);
1189 close(startup_p[1]);
1192 send_rexec_state(config_s[0], &cfg);
1198 * Mark that the key has been used (it
1199 * was "given" to the child).
1201 if ((options.protocol & SSH_PROTO_1) &&
1203 /* Schedule server key regeneration alarm. */
1204 signal(SIGALRM, key_regeneration_alarm);
1205 alarm(options.key_regeneration_time);
1212 * Ensure that our random state differs
1213 * from that of the child
1218 /* child process check (or debug mode) */
1219 if (num_listen_socks < 0)
1226 * Main program for the daemon.
1229 main(int ac, char **av)
1231 extern char *optarg;
1234 int sock_in = -1, sock_out = -1, newsock = -1;
1235 const char *remote_ip;
1238 int config_s[2] = { -1 , -1 };
1242 #ifdef HAVE_SECUREWARE
1243 (void)set_auth_parameters(ac, av);
1245 __progname = ssh_get_progname(av[0]);
1248 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1251 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1252 for (i = 0; i < ac; i++)
1253 saved_argv[i] = xstrdup(av[i]);
1254 saved_argv[i] = NULL;
1256 #ifndef HAVE_SETPROCTITLE
1257 /* Prepare for later setproctitle emulation */
1258 compat_init_setproctitle(ac, av);
1262 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1263 debug("setgroups(): %.200s", strerror(errno));
1265 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1268 /* Initialize configuration options to their default values. */
1269 initialize_server_options(&options);
1271 /* Parse command-line arguments. */
1272 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
1275 options.address_family = AF_INET;
1278 options.address_family = AF_INET6;
1281 config_file_name = optarg;
1284 if (debug_flag == 0) {
1286 options.log_level = SYSLOG_LEVEL_DEBUG1;
1287 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1288 options.log_level++;
1310 options.log_level = SYSLOG_LEVEL_QUIET;
1313 options.server_key_bits = (int)strtonum(optarg, 256,
1317 options.ports_from_cmdline = 1;
1318 if (options.num_ports >= MAX_PORTS) {
1319 fprintf(stderr, "too many ports.\n");
1322 options.ports[options.num_ports++] = a2port(optarg);
1323 if (options.ports[options.num_ports-1] == 0) {
1324 fprintf(stderr, "Bad port number.\n");
1329 if ((options.login_grace_time = convtime(optarg)) == -1) {
1330 fprintf(stderr, "Invalid login grace time.\n");
1335 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1336 fprintf(stderr, "Invalid key regeneration interval.\n");
1341 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1342 fprintf(stderr, "too many host keys.\n");
1345 options.host_key_files[options.num_host_key_files++] = optarg;
1351 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1352 if (utmp_len > MAXHOSTNAMELEN) {
1353 fprintf(stderr, "Invalid utmp length.\n");
1358 line = xstrdup(optarg);
1359 if (process_server_config_line(&options, line,
1360 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1370 if (rexeced_flag || inetd_flag)
1372 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1373 fatal("sshd re-exec requires execution with an absolute path");
1375 closefrom(REEXEC_MIN_FREE_FD);
1377 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1379 SSLeay_add_all_algorithms();
1382 * Force logging to stderr until we have loaded the private host
1383 * key (unless started from inetd)
1385 log_init(__progname,
1386 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1387 SYSLOG_LEVEL_INFO : options.log_level,
1388 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1389 SYSLOG_FACILITY_AUTH : options.log_facility,
1390 log_stderr || !inetd_flag);
1393 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1394 * root's environment
1396 if (getenv("KRB5CCNAME") != NULL)
1397 unsetenv("KRB5CCNAME");
1400 /* Cray can define user privs drop all privs now!
1401 * Not needed on PRIV_SU systems!
1406 sensitive_data.server_key = NULL;
1407 sensitive_data.ssh1_host_key = NULL;
1408 sensitive_data.have_ssh1_key = 0;
1409 sensitive_data.have_ssh2_key = 0;
1411 /* Fetch our configuration */
1414 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1416 load_server_config(config_file_name, &cfg);
1418 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1419 &cfg, NULL, NULL, NULL);
1423 /* Fill in default values for those options not explicitly set. */
1424 fill_default_server_options(&options);
1426 /* set default channel AF */
1427 channel_set_af(options.address_family);
1429 /* Check that there are no remaining arguments. */
1431 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1435 debug("sshd version %.100s", SSH_RELEASE);
1437 /* load private host keys */
1438 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1440 for (i = 0; i < options.num_host_key_files; i++)
1441 sensitive_data.host_keys[i] = NULL;
1443 for (i = 0; i < options.num_host_key_files; i++) {
1444 key = key_load_private(options.host_key_files[i], "", NULL);
1445 sensitive_data.host_keys[i] = key;
1447 error("Could not load host key: %s",
1448 options.host_key_files[i]);
1449 sensitive_data.host_keys[i] = NULL;
1452 switch (key->type) {
1454 sensitive_data.ssh1_host_key = key;
1455 sensitive_data.have_ssh1_key = 1;
1459 sensitive_data.have_ssh2_key = 1;
1462 debug("private host key: #%d type %d %s", i, key->type,
1465 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1466 logit("Disabling protocol version 1. Could not load host key");
1467 options.protocol &= ~SSH_PROTO_1;
1469 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1470 logit("Disabling protocol version 2. Could not load host key");
1471 options.protocol &= ~SSH_PROTO_2;
1473 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1474 logit("sshd: no hostkeys available -- exiting.");
1478 /* Check certain values for sanity. */
1479 if (options.protocol & SSH_PROTO_1) {
1480 if (options.server_key_bits < 512 ||
1481 options.server_key_bits > 32768) {
1482 fprintf(stderr, "Bad server key size.\n");
1486 * Check that server and host key lengths differ sufficiently. This
1487 * is necessary to make double encryption work with rsaref. Oh, I
1488 * hate software patents. I dont know if this can go? Niels
1490 if (options.server_key_bits >
1491 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1492 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1493 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1494 SSH_KEY_BITS_RESERVED) {
1495 options.server_key_bits =
1496 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1497 SSH_KEY_BITS_RESERVED;
1498 debug("Forcing server key to %d bits to make it differ from host key.",
1499 options.server_key_bits);
1506 if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1507 fatal("Privilege separation user %s does not exist",
1509 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1510 (S_ISDIR(st.st_mode) == 0))
1511 fatal("Missing privilege separation directory: %s",
1512 _PATH_PRIVSEP_CHROOT_DIR);
1515 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1516 (st.st_uid != getuid () ||
1517 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1519 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1521 fatal("%s must be owned by root and not group or "
1522 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1525 /* Configuration looks good, so exit if in test mode. */
1530 * Clear out any supplemental groups we may have inherited. This
1531 * prevents inadvertent creation of files with bad modes (in the
1532 * portable version at least, it's certainly possible for PAM
1533 * to create a file, and we can't control the code in every
1534 * module which might be used).
1536 if (setgroups(0, NULL) < 0)
1537 debug("setgroups() failed: %.200s", strerror(errno));
1540 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1541 for (i = 0; i < rexec_argc; i++) {
1542 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1543 rexec_argv[i] = saved_argv[i];
1545 rexec_argv[rexec_argc] = "-R";
1546 rexec_argv[rexec_argc + 1] = NULL;
1549 /* Initialize the log (it is reinitialized below in case we forked). */
1550 if (debug_flag && (!inetd_flag || rexeced_flag))
1552 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1555 * If not in debugging mode, and not started from inetd, disconnect
1556 * from the controlling terminal, and fork. The original process
1559 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1562 #endif /* TIOCNOTTY */
1563 if (daemon(0, 0) < 0)
1564 fatal("daemon() failed: %.200s", strerror(errno));
1566 /* Disconnect from the controlling tty. */
1568 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1570 (void) ioctl(fd, TIOCNOTTY, NULL);
1573 #endif /* TIOCNOTTY */
1575 /* Reinitialize the log (because of the fork above). */
1576 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1578 /* Initialize the random number generator. */
1581 /* Chdir to the root directory so that the current disk can be
1582 unmounted if desired. */
1585 /* ignore SIGPIPE */
1586 signal(SIGPIPE, SIG_IGN);
1588 /* Get a connection, either from inetd or a listening TCP socket */
1590 server_accept_inetd(&sock_in, &sock_out);
1592 if ((options.protocol & SSH_PROTO_1) &&
1593 sensitive_data.server_key == NULL)
1594 generate_ephemeral_server_key();
1598 if (options.protocol & SSH_PROTO_1)
1599 generate_ephemeral_server_key();
1601 signal(SIGHUP, sighup_handler);
1602 signal(SIGCHLD, main_sigchld_handler);
1603 signal(SIGTERM, sigterm_handler);
1604 signal(SIGQUIT, sigterm_handler);
1607 * Write out the pid file after the sigterm handler
1608 * is setup and the listen sockets are bound
1611 FILE *f = fopen(options.pid_file, "w");
1614 error("Couldn't create pid file \"%s\": %s",
1615 options.pid_file, strerror(errno));
1617 fprintf(f, "%ld\n", (long) getpid());
1622 /* Accept a connection and return in a forked child */
1623 server_accept_loop(&sock_in, &sock_out,
1624 &newsock, config_s);
1627 /* This is the child processing a new connection. */
1628 setproctitle("%s", "[accepted]");
1631 * Create a new session and process group since the 4.4BSD
1632 * setlogin() affects the entire process group. We don't
1633 * want the child to be able to affect the parent.
1635 #if !defined(SSHD_ACQUIRES_CTTY)
1637 * If setsid is called, on some platforms sshd will later acquire a
1638 * controlling terminal which will result in "could not set
1639 * controlling tty" errors.
1641 if (!debug_flag && !inetd_flag && setsid() < 0)
1642 error("setsid: %.100s", strerror(errno));
1648 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1649 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1650 dup2(newsock, STDIN_FILENO);
1651 dup2(STDIN_FILENO, STDOUT_FILENO);
1652 if (startup_pipe == -1)
1653 close(REEXEC_STARTUP_PIPE_FD);
1655 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1657 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1659 if (startup_pipe != -1)
1660 close(startup_pipe);
1662 execv(rexec_argv[0], rexec_argv);
1664 /* Reexec has failed, fall back and continue */
1665 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1666 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1667 log_init(__progname, options.log_level,
1668 options.log_facility, log_stderr);
1671 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1673 close(REEXEC_CONFIG_PASS_FD);
1674 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1675 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1676 dup2(fd, STDIN_FILENO);
1677 dup2(fd, STDOUT_FILENO);
1678 if (fd > STDERR_FILENO)
1681 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1682 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1686 * Disable the key regeneration alarm. We will not regenerate the
1687 * key since we are no longer in a position to give it to anyone. We
1688 * will not restart on SIGHUP since it no longer makes sense.
1691 signal(SIGALRM, SIG_DFL);
1692 signal(SIGHUP, SIG_DFL);
1693 signal(SIGTERM, SIG_DFL);
1694 signal(SIGQUIT, SIG_DFL);
1695 signal(SIGCHLD, SIG_DFL);
1696 signal(SIGINT, SIG_DFL);
1699 * Register our connection. This turns encryption off because we do
1702 packet_set_connection(sock_in, sock_out);
1703 packet_set_server();
1705 /* Set SO_KEEPALIVE if requested. */
1706 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1707 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1708 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1710 if ((remote_port = get_remote_port()) < 0) {
1711 debug("get_remote_port failed");
1716 * We use get_canonical_hostname with usedns = 0 instead of
1717 * get_remote_ipaddr here so IP options will be checked.
1719 (void) get_canonical_hostname(0);
1721 * The rest of the code depends on the fact that
1722 * get_remote_ipaddr() caches the remote ip, even if
1723 * the socket goes away.
1725 remote_ip = get_remote_ipaddr();
1727 #ifdef SSH_AUDIT_EVENTS
1728 audit_connection_from(remote_ip, remote_port);
1731 /* Check whether logins are denied from this host. */
1732 if (packet_connection_is_on_socket()) {
1733 struct request_info req;
1735 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1738 if (!hosts_access(&req)) {
1739 debug("Connection refused by tcp wrapper");
1742 fatal("libwrap refuse returns");
1745 #endif /* LIBWRAP */
1747 /* Log the connection. */
1748 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1751 * We don't want to listen forever unless the other side
1752 * successfully authenticates itself. So we set up an alarm which is
1753 * cleared after successful authentication. A limit of zero
1754 * indicates no limit. Note that we don't set the alarm in debugging
1755 * mode; it is just annoying to have the server exit just when you
1756 * are about to discover the bug.
1758 signal(SIGALRM, grace_alarm_handler);
1760 alarm(options.login_grace_time);
1762 sshd_exchange_identification(sock_in, sock_out);
1764 packet_set_nonblocking();
1766 /* allocate authentication context */
1767 authctxt = xcalloc(1, sizeof(*authctxt));
1769 authctxt->loginmsg = &loginmsg;
1771 /* XXX global for cleanup, access from other modules */
1772 the_authctxt = authctxt;
1774 /* prepare buffer to collect messages to display to user after login */
1775 buffer_init(&loginmsg);
1778 if (privsep_preauth(authctxt) == 1)
1781 /* perform the key exchange */
1782 /* authenticate user and start session */
1785 do_authentication2(authctxt);
1788 do_authentication(authctxt);
1791 * If we use privilege separation, the unprivileged child transfers
1792 * the current keystate and exits
1795 mm_send_keystate(pmonitor);
1801 * Cancel the alarm we set to limit the time taken for
1805 signal(SIGALRM, SIG_DFL);
1806 authctxt->authenticated = 1;
1807 if (startup_pipe != -1) {
1808 close(startup_pipe);
1812 #ifdef SSH_AUDIT_EVENTS
1813 audit_event(SSH_AUTH_SUCCESS);
1817 * In privilege separation, we fork another child and prepare
1818 * file descriptor passing.
1821 privsep_postauth(authctxt);
1822 /* the monitor process [priv] will not return */
1824 destroy_sensitive_data();
1827 /* Start session. */
1828 do_authenticated(authctxt);
1830 /* The connection has been terminated. */
1831 verbose("Closing connection to %.100s", remote_ip);
1834 if (options.use_pam)
1836 #endif /* USE_PAM */
1838 #ifdef SSH_AUDIT_EVENTS
1839 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1851 * Decrypt session_key_int using our private server key and private host key
1852 * (key with larger modulus first).
1855 ssh1_session_key(BIGNUM *session_key_int)
1859 if (BN_cmp(sensitive_data.server_key->rsa->n,
1860 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1861 /* Server key has bigger modulus. */
1862 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1863 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1864 SSH_KEY_BITS_RESERVED) {
1865 fatal("do_connection: %s: "
1866 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1867 get_remote_ipaddr(),
1868 BN_num_bits(sensitive_data.server_key->rsa->n),
1869 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1870 SSH_KEY_BITS_RESERVED);
1872 if (rsa_private_decrypt(session_key_int, session_key_int,
1873 sensitive_data.server_key->rsa) <= 0)
1875 if (rsa_private_decrypt(session_key_int, session_key_int,
1876 sensitive_data.ssh1_host_key->rsa) <= 0)
1879 /* Host key has bigger modulus (or they are equal). */
1880 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1881 BN_num_bits(sensitive_data.server_key->rsa->n) +
1882 SSH_KEY_BITS_RESERVED) {
1883 fatal("do_connection: %s: "
1884 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1885 get_remote_ipaddr(),
1886 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1887 BN_num_bits(sensitive_data.server_key->rsa->n),
1888 SSH_KEY_BITS_RESERVED);
1890 if (rsa_private_decrypt(session_key_int, session_key_int,
1891 sensitive_data.ssh1_host_key->rsa) < 0)
1893 if (rsa_private_decrypt(session_key_int, session_key_int,
1894 sensitive_data.server_key->rsa) < 0)
1907 BIGNUM *session_key_int;
1908 u_char session_key[SSH_SESSION_KEY_LENGTH];
1910 u_int cipher_type, auth_mask, protocol_flags;
1914 * Generate check bytes that the client must send back in the user
1915 * packet in order for it to be accepted; this is used to defy ip
1916 * spoofing attacks. Note that this only works against somebody
1917 * doing IP spoofing from a remote machine; any machine on the local
1918 * network can still see outgoing packets and catch the random
1919 * cookie. This only affects rhosts authentication, and this is one
1920 * of the reasons why it is inherently insecure.
1922 for (i = 0; i < 8; i++) {
1925 cookie[i] = rnd & 0xff;
1930 * Send our public key. We include in the packet 64 bits of random
1931 * data that must be matched in the reply in order to prevent IP
1934 packet_start(SSH_SMSG_PUBLIC_KEY);
1935 for (i = 0; i < 8; i++)
1936 packet_put_char(cookie[i]);
1938 /* Store our public server RSA key. */
1939 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1940 packet_put_bignum(sensitive_data.server_key->rsa->e);
1941 packet_put_bignum(sensitive_data.server_key->rsa->n);
1943 /* Store our public host RSA key. */
1944 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1945 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1946 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1948 /* Put protocol flags. */
1949 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1951 /* Declare which ciphers we support. */
1952 packet_put_int(cipher_mask_ssh1(0));
1954 /* Declare supported authentication types. */
1956 if (options.rhosts_rsa_authentication)
1957 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1958 if (options.rsa_authentication)
1959 auth_mask |= 1 << SSH_AUTH_RSA;
1960 if (options.challenge_response_authentication == 1)
1961 auth_mask |= 1 << SSH_AUTH_TIS;
1962 if (options.password_authentication)
1963 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1964 packet_put_int(auth_mask);
1966 /* Send the packet and wait for it to be sent. */
1968 packet_write_wait();
1970 debug("Sent %d bit server key and %d bit host key.",
1971 BN_num_bits(sensitive_data.server_key->rsa->n),
1972 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1974 /* Read clients reply (cipher type and session key). */
1975 packet_read_expect(SSH_CMSG_SESSION_KEY);
1977 /* Get cipher type and check whether we accept this. */
1978 cipher_type = packet_get_char();
1980 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1981 packet_disconnect("Warning: client selects unsupported cipher.");
1983 /* Get check bytes from the packet. These must match those we
1984 sent earlier with the public key packet. */
1985 for (i = 0; i < 8; i++)
1986 if (cookie[i] != packet_get_char())
1987 packet_disconnect("IP Spoofing check bytes do not match.");
1989 debug("Encryption type: %.200s", cipher_name(cipher_type));
1991 /* Get the encrypted integer. */
1992 if ((session_key_int = BN_new()) == NULL)
1993 fatal("do_ssh1_kex: BN_new failed");
1994 packet_get_bignum(session_key_int);
1996 protocol_flags = packet_get_int();
1997 packet_set_protocol_flags(protocol_flags);
2000 /* Decrypt session_key_int using host/server keys */
2001 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2004 * Extract session key from the decrypted integer. The key is in the
2005 * least significant 256 bits of the integer; the first byte of the
2006 * key is in the highest bits.
2009 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2010 len = BN_num_bytes(session_key_int);
2011 if (len < 0 || (u_int)len > sizeof(session_key)) {
2012 error("do_connection: bad session key len from %s: "
2013 "session_key_int %d > sizeof(session_key) %lu",
2014 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2017 memset(session_key, 0, sizeof(session_key));
2018 BN_bn2bin(session_key_int,
2019 session_key + sizeof(session_key) - len);
2021 derive_ssh1_session_id(
2022 sensitive_data.ssh1_host_key->rsa->n,
2023 sensitive_data.server_key->rsa->n,
2024 cookie, session_id);
2026 * Xor the first 16 bytes of the session key with the
2029 for (i = 0; i < 16; i++)
2030 session_key[i] ^= session_id[i];
2034 int bytes = BN_num_bytes(session_key_int);
2035 u_char *buf = xmalloc(bytes);
2038 logit("do_connection: generating a fake encryption key");
2039 BN_bn2bin(session_key_int, buf);
2041 MD5_Update(&md, buf, bytes);
2042 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2043 MD5_Final(session_key, &md);
2045 MD5_Update(&md, session_key, 16);
2046 MD5_Update(&md, buf, bytes);
2047 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2048 MD5_Final(session_key + 16, &md);
2049 memset(buf, 0, bytes);
2051 for (i = 0; i < 16; i++)
2052 session_id[i] = session_key[i] ^ session_key[i + 16];
2054 /* Destroy the private and public keys. No longer. */
2055 destroy_sensitive_data();
2058 mm_ssh1_session_id(session_id);
2060 /* Destroy the decrypted integer. It is no longer needed. */
2061 BN_clear_free(session_key_int);
2063 /* Set the session key. From this on all communications will be encrypted. */
2064 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2066 /* Destroy our copy of the session key. It is no longer needed. */
2067 memset(session_key, 0, sizeof(session_key));
2069 debug("Received session key; encryption turned on.");
2071 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2072 packet_start(SSH_SMSG_SUCCESS);
2074 packet_write_wait();
2078 * SSH2 key exchange: diffie-hellman-group1-sha1
2085 if (options.ciphers != NULL) {
2086 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2087 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2089 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2090 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2091 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2092 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2094 if (options.macs != NULL) {
2095 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2096 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2098 if (options.compression == COMP_NONE) {
2099 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2100 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2101 } else if (options.compression == COMP_DELAYED) {
2102 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2103 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2106 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2108 /* start key exchange */
2109 kex = kex_setup(myproposal);
2110 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2111 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2112 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2113 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2115 kex->client_version_string=client_version_string;
2116 kex->server_version_string=server_version_string;
2117 kex->load_host_key=&get_hostkey_by_type;
2118 kex->host_key_index=&get_hostkey_index;
2122 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2124 session_id2 = kex->session_id;
2125 session_id2_len = kex->session_id_len;
2128 /* send 1st encrypted/maced/compressed message */
2129 packet_start(SSH2_MSG_IGNORE);
2130 packet_put_cstring("markus");
2132 packet_write_wait();
2137 /* server specific fatal cleanup */
2142 do_cleanup(the_authctxt);
2143 #ifdef SSH_AUDIT_EVENTS
2144 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2145 if (!use_privsep || mm_is_monitor())
2146 audit_event(SSH_CONNECTION_ABANDON);