2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * This program is the ssh daemon. It listens for connections from clients,
6 * and performs authentication, executes use commands or shell, and forwards
7 * information to/from the application to the user client over an encrypted
8 * connection. This can also handle forwarding of X11, TCP/IP, and
9 * authentication agent connections.
11 * As far as I am concerned, the code I have written for this software
12 * can be used freely for any purpose. Any derived versions of this
13 * software must be clearly marked as such, and if the derived work is
14 * incompatible with the protocol description in the RFC file, it must be
15 * called by a name other than "ssh" or "Secure Shell".
17 * SSH2 implementation:
18 * Privilege Separation:
20 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
21 * Copyright (c) 2002 Niels Provos. All rights reserved.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the above copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
32 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
33 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
34 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
35 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
36 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
37 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
38 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
39 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
40 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
41 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
45 RCSID("$OpenBSD: sshd.c,v 1.312 2005/07/25 11:59:40 markus Exp $");
48 #include <openssl/dh.h>
49 #include <openssl/bn.h>
50 #include <openssl/md5.h>
51 #include <openssl/rand.h>
52 #ifdef HAVE_SECUREWARE
53 #include <sys/security.h>
60 #include <gssapi/gssapi.h>
81 #include "myproposal.h"
83 #include "pathnames.h"
92 #include "monitor_mm.h"
94 #include "monitor_wrap.h"
95 #include "monitor_fdpass.h"
100 int allow_severity = LOG_INFO;
101 int deny_severity = LOG_WARNING;
109 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
110 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
111 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
112 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
114 extern char *__progname;
116 /* Server configuration options. */
117 ServerOptions options;
119 /* Name of the server configuration file. */
120 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
123 * Debug mode flag. This can be set on the command line. If debug
124 * mode is enabled, extra debugging output will be sent to the system
125 * log, the daemon will not go to background, and will exit after processing
126 * the first connection.
130 /* Flag indicating that the daemon should only test the configuration and keys. */
133 /* Flag indicating that the daemon is being started from inetd. */
136 /* Flag indicating that sshd should not detach and become a daemon. */
137 int no_daemon_flag = 0;
139 /* debug goes to stderr unless inetd_flag is set */
142 /* Saved arguments to main(). */
147 int rexeced_flag = 0;
153 * The sockets that the server is listening; this is used in the SIGHUP
156 #define MAX_LISTEN_SOCKS 16
157 int listen_socks[MAX_LISTEN_SOCKS];
158 int num_listen_socks = 0;
161 * the client's version string, passed by sshd2 in compat mode. if != NULL,
162 * sshd will skip the version-number exchange
164 char *client_version_string = NULL;
165 char *server_version_string = NULL;
167 /* for rekeying XXX fixme */
171 * Any really sensitive data in the application is contained in this
172 * structure. The idea is that this structure could be locked into memory so
173 * that the pages do not get written into swap. However, there are some
174 * problems. The private key contains BIGNUMs, and we do not (in principle)
175 * have access to the internals of them, and locking just the structure is
176 * not very useful. Currently, memory locking is not implemented.
179 Key *server_key; /* ephemeral server key */
180 Key *ssh1_host_key; /* ssh1 host key */
181 Key **host_keys; /* all private host keys */
184 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
188 * Flag indicating whether the RSA server key needs to be regenerated.
189 * Is set in the SIGALRM handler and cleared when the key is regenerated.
191 static volatile sig_atomic_t key_do_regen = 0;
193 /* This is set to true when a signal is received. */
194 static volatile sig_atomic_t received_sighup = 0;
195 static volatile sig_atomic_t received_sigterm = 0;
197 /* session identifier, used by RSA-auth */
198 u_char session_id[16];
201 u_char *session_id2 = NULL;
202 u_int session_id2_len = 0;
204 /* record remote hostname or ip */
205 u_int utmp_len = MAXHOSTNAMELEN;
207 /* options.max_startup sized array of fd ints */
208 int *startup_pipes = NULL;
209 int startup_pipe; /* in child */
211 /* variables used for privilege separation */
213 struct monitor *pmonitor = NULL;
215 /* global authentication context */
216 Authctxt *the_authctxt = NULL;
218 /* message to be displayed after login */
221 /* Prototypes for various functions defined later in this file. */
222 void destroy_sensitive_data(void);
223 void demote_sensitive_data(void);
225 static void do_ssh1_kex(void);
226 static void do_ssh2_kex(void);
229 * Close all listening sockets
232 close_listen_socks(void)
236 for (i = 0; i < num_listen_socks; i++)
237 close(listen_socks[i]);
238 num_listen_socks = -1;
242 close_startup_pipes(void)
247 for (i = 0; i < options.max_startups; i++)
248 if (startup_pipes[i] != -1)
249 close(startup_pipes[i]);
253 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
254 * the effect is to reread the configuration file (and to regenerate
258 sighup_handler(int sig)
260 int save_errno = errno;
263 signal(SIGHUP, sighup_handler);
268 * Called from the main program after receiving SIGHUP.
269 * Restarts the server.
274 logit("Received SIGHUP; restarting.");
275 close_listen_socks();
276 close_startup_pipes();
277 execv(saved_argv[0], saved_argv);
278 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
284 * Generic signal handler for terminating signals in the master daemon.
287 sigterm_handler(int sig)
289 received_sigterm = sig;
293 * SIGCHLD handler. This is called whenever a child dies. This will then
294 * reap any zombies left by exited children.
297 main_sigchld_handler(int sig)
299 int save_errno = errno;
303 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
304 (pid < 0 && errno == EINTR))
307 signal(SIGCHLD, main_sigchld_handler);
312 * Signal handler for the alarm after the login grace period has expired.
315 grace_alarm_handler(int sig)
317 /* XXX no idea how fix this signal handler */
319 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
320 kill(pmonitor->m_pid, SIGALRM);
322 /* Log error and exit. */
323 fatal("Timeout before authentication for %s", get_remote_ipaddr());
327 * Signal handler for the key regeneration alarm. Note that this
328 * alarm only occurs in the daemon waiting for connections, and it does not
329 * do anything with the private key or random state before forking.
330 * Thus there should be no concurrency control/asynchronous execution
334 generate_ephemeral_server_key(void)
339 verbose("Generating %s%d bit RSA key.",
340 sensitive_data.server_key ? "new " : "", options.server_key_bits);
341 if (sensitive_data.server_key != NULL)
342 key_free(sensitive_data.server_key);
343 sensitive_data.server_key = key_generate(KEY_RSA1,
344 options.server_key_bits);
345 verbose("RSA key generation complete.");
347 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
350 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
357 key_regeneration_alarm(int sig)
359 int save_errno = errno;
361 signal(SIGALRM, SIG_DFL);
367 sshd_exchange_identification(int sock_in, int sock_out)
371 int remote_major, remote_minor;
374 char buf[256]; /* Must not be larger than remote_version. */
375 char remote_version[256]; /* Must be at least as big as buf. */
377 if ((options.protocol & SSH_PROTO_1) &&
378 (options.protocol & SSH_PROTO_2)) {
379 major = PROTOCOL_MAJOR_1;
381 } else if (options.protocol & SSH_PROTO_2) {
382 major = PROTOCOL_MAJOR_2;
383 minor = PROTOCOL_MINOR_2;
385 major = PROTOCOL_MAJOR_1;
386 minor = PROTOCOL_MINOR_1;
388 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
389 server_version_string = xstrdup(buf);
391 /* Send our protocol version identification. */
392 if (atomicio(vwrite, sock_out, server_version_string,
393 strlen(server_version_string))
394 != strlen(server_version_string)) {
395 logit("Could not write ident string to %s", get_remote_ipaddr());
399 /* Read other sides version identification. */
400 memset(buf, 0, sizeof(buf));
401 for (i = 0; i < sizeof(buf) - 1; i++) {
402 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
403 logit("Did not receive identification string from %s",
404 get_remote_ipaddr());
407 if (buf[i] == '\r') {
409 /* Kludge for F-Secure Macintosh < 1.0.2 */
411 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
415 if (buf[i] == '\n') {
420 buf[sizeof(buf) - 1] = 0;
421 client_version_string = xstrdup(buf);
424 * Check that the versions match. In future this might accept
425 * several versions and set appropriate flags to handle them.
427 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
428 &remote_major, &remote_minor, remote_version) != 3) {
429 s = "Protocol mismatch.\n";
430 (void) atomicio(vwrite, sock_out, s, strlen(s));
433 logit("Bad protocol version identification '%.100s' from %s",
434 client_version_string, get_remote_ipaddr());
437 debug("Client protocol version %d.%d; client software version %.100s",
438 remote_major, remote_minor, remote_version);
440 compat_datafellows(remote_version);
442 if (datafellows & SSH_BUG_PROBE) {
443 logit("probed from %s with %s. Don't panic.",
444 get_remote_ipaddr(), client_version_string);
448 if (datafellows & SSH_BUG_SCANNER) {
449 logit("scanned from %s with %s. Don't panic.",
450 get_remote_ipaddr(), client_version_string);
455 switch (remote_major) {
457 if (remote_minor == 99) {
458 if (options.protocol & SSH_PROTO_2)
464 if (!(options.protocol & SSH_PROTO_1)) {
468 if (remote_minor < 3) {
469 packet_disconnect("Your ssh version is too old and "
470 "is no longer supported. Please install a newer version.");
471 } else if (remote_minor == 3) {
472 /* note that this disables agent-forwarding */
477 if (options.protocol & SSH_PROTO_2) {
486 chop(server_version_string);
487 debug("Local version string %.200s", server_version_string);
490 s = "Protocol major versions differ.\n";
491 (void) atomicio(vwrite, sock_out, s, strlen(s));
494 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
496 server_version_string, client_version_string);
501 /* Destroy the host and server keys. They will no longer be needed. */
503 destroy_sensitive_data(void)
507 if (sensitive_data.server_key) {
508 key_free(sensitive_data.server_key);
509 sensitive_data.server_key = NULL;
511 for (i = 0; i < options.num_host_key_files; i++) {
512 if (sensitive_data.host_keys[i]) {
513 key_free(sensitive_data.host_keys[i]);
514 sensitive_data.host_keys[i] = NULL;
517 sensitive_data.ssh1_host_key = NULL;
518 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
521 /* Demote private to public keys for network child */
523 demote_sensitive_data(void)
528 if (sensitive_data.server_key) {
529 tmp = key_demote(sensitive_data.server_key);
530 key_free(sensitive_data.server_key);
531 sensitive_data.server_key = tmp;
534 for (i = 0; i < options.num_host_key_files; i++) {
535 if (sensitive_data.host_keys[i]) {
536 tmp = key_demote(sensitive_data.host_keys[i]);
537 key_free(sensitive_data.host_keys[i]);
538 sensitive_data.host_keys[i] = tmp;
539 if (tmp->type == KEY_RSA1)
540 sensitive_data.ssh1_host_key = tmp;
544 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
548 privsep_preauth_child(void)
555 /* Enable challenge-response authentication for privilege separation */
556 privsep_challenge_enable();
558 for (i = 0; i < 256; i++)
559 rnd[i] = arc4random();
560 RAND_seed(rnd, sizeof(rnd));
562 /* Demote the private keys to public keys. */
563 demote_sensitive_data();
565 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
566 fatal("Privilege separation user %s does not exist",
568 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
571 /* Change our root directory */
572 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
573 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
575 if (chdir("/") == -1)
576 fatal("chdir(\"/\"): %s", strerror(errno));
578 /* Drop our privileges */
579 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
582 /* XXX not ready, too heavy after chroot */
583 do_setusercontext(pw);
585 gidset[0] = pw->pw_gid;
586 if (setgroups(1, gidset) < 0)
587 fatal("setgroups: %.100s", strerror(errno));
588 permanently_set_uid(pw);
593 privsep_preauth(Authctxt *authctxt)
598 /* Set up unprivileged child process to deal with network data */
599 pmonitor = monitor_init();
600 /* Store a pointer to the kex for later rekeying */
601 pmonitor->m_pkex = &xxx_kex;
605 fatal("fork of unprivileged child failed");
606 } else if (pid != 0) {
607 debug2("Network child is on pid %ld", (long)pid);
609 close(pmonitor->m_recvfd);
610 pmonitor->m_pid = pid;
611 monitor_child_preauth(authctxt, pmonitor);
612 close(pmonitor->m_sendfd);
615 monitor_sync(pmonitor);
617 /* Wait for the child's exit status */
618 while (waitpid(pid, &status, 0) < 0)
625 close(pmonitor->m_sendfd);
627 /* Demote the child */
628 if (getuid() == 0 || geteuid() == 0)
629 privsep_preauth_child();
630 setproctitle("%s", "[net]");
636 privsep_postauth(Authctxt *authctxt)
638 #ifdef DISABLE_FD_PASSING
641 if (authctxt->pw->pw_uid == 0 || options.use_login) {
643 /* File descriptor passing is broken or root login */
644 monitor_apply_keystate(pmonitor);
649 /* Authentication complete */
651 if (startup_pipe != -1) {
656 /* New socket pair */
657 monitor_reinit(pmonitor);
659 pmonitor->m_pid = fork();
660 if (pmonitor->m_pid == -1)
661 fatal("fork of unprivileged child failed");
662 else if (pmonitor->m_pid != 0) {
663 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
664 close(pmonitor->m_recvfd);
665 buffer_clear(&loginmsg);
666 monitor_child_postauth(pmonitor);
672 close(pmonitor->m_sendfd);
674 /* Demote the private keys to public keys. */
675 demote_sensitive_data();
677 /* Drop privileges */
678 do_setusercontext(authctxt->pw);
680 /* It is safe now to apply the key state */
681 monitor_apply_keystate(pmonitor);
684 * Tell the packet layer that authentication was successful, since
685 * this information is not part of the key state.
687 packet_set_authenticated();
691 list_hostkey_types(void)
699 for (i = 0; i < options.num_host_key_files; i++) {
700 Key *key = sensitive_data.host_keys[i];
706 if (buffer_len(&b) > 0)
707 buffer_append(&b, ",", 1);
708 p = key_ssh_name(key);
709 buffer_append(&b, p, strlen(p));
713 buffer_append(&b, "\0", 1);
714 ret = xstrdup(buffer_ptr(&b));
716 debug("list_hostkey_types: %s", ret);
721 get_hostkey_by_type(int type)
725 for (i = 0; i < options.num_host_key_files; i++) {
726 Key *key = sensitive_data.host_keys[i];
727 if (key != NULL && key->type == type)
734 get_hostkey_by_index(int ind)
736 if (ind < 0 || ind >= options.num_host_key_files)
738 return (sensitive_data.host_keys[ind]);
742 get_hostkey_index(Key *key)
746 for (i = 0; i < options.num_host_key_files; i++) {
747 if (key == sensitive_data.host_keys[i])
754 * returns 1 if connection should be dropped, 0 otherwise.
755 * dropping starts at connection #max_startups_begin with a probability
756 * of (max_startups_rate/100). the probability increases linearly until
757 * all connections are dropped for startups > max_startups
760 drop_connection(int startups)
764 if (startups < options.max_startups_begin)
766 if (startups >= options.max_startups)
768 if (options.max_startups_rate == 100)
771 p = 100 - options.max_startups_rate;
772 p *= startups - options.max_startups_begin;
773 p /= options.max_startups - options.max_startups_begin;
774 p += options.max_startups_rate;
775 r = arc4random() % 100;
777 debug("drop_connection: p %d, r %d", p, r);
778 return (r < p) ? 1 : 0;
784 fprintf(stderr, "%s, %s\n",
785 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
787 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
788 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
794 send_rexec_state(int fd, Buffer *conf)
798 debug3("%s: entering fd = %d config len %d", __func__, fd,
802 * Protocol from reexec master to child:
803 * string configuration
804 * u_int ephemeral_key_follows
805 * bignum e (only if ephemeral_key_follows == 1)
813 buffer_put_cstring(&m, buffer_ptr(conf));
815 if (sensitive_data.server_key != NULL &&
816 sensitive_data.server_key->type == KEY_RSA1) {
817 buffer_put_int(&m, 1);
818 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
819 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
820 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
821 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
822 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
823 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
825 buffer_put_int(&m, 0);
827 if (ssh_msg_send(fd, 0, &m) == -1)
828 fatal("%s: ssh_msg_send failed", __func__);
832 debug3("%s: done", __func__);
836 recv_rexec_state(int fd, Buffer *conf)
842 debug3("%s: entering fd = %d", __func__, fd);
846 if (ssh_msg_recv(fd, &m) == -1)
847 fatal("%s: ssh_msg_recv failed", __func__);
848 if (buffer_get_char(&m) != 0)
849 fatal("%s: rexec version mismatch", __func__);
851 cp = buffer_get_string(&m, &len);
853 buffer_append(conf, cp, len + 1);
856 if (buffer_get_int(&m)) {
857 if (sensitive_data.server_key != NULL)
858 key_free(sensitive_data.server_key);
859 sensitive_data.server_key = key_new_private(KEY_RSA1);
860 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
861 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
862 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
863 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
864 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
865 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
866 rsa_generate_additional_parameters(
867 sensitive_data.server_key->rsa);
871 debug3("%s: done", __func__);
875 * Main program for the daemon.
878 main(int ac, char **av)
882 int opt, j, i, fdsetsz, on = 1;
883 int sock_in = -1, sock_out = -1, newsock = -1;
887 struct sockaddr_storage from;
888 const char *remote_ip;
892 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
894 int listen_sock, maxfd;
895 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
899 int ret, key_used = 0;
902 #ifdef HAVE_SECUREWARE
903 (void)set_auth_parameters(ac, av);
905 __progname = ssh_get_progname(av[0]);
908 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
911 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
912 for (i = 0; i < ac; i++)
913 saved_argv[i] = xstrdup(av[i]);
914 saved_argv[i] = NULL;
916 #ifndef HAVE_SETPROCTITLE
917 /* Prepare for later setproctitle emulation */
918 compat_init_setproctitle(ac, av);
922 if (geteuid() == 0 && setgroups(0, NULL) == -1)
923 debug("setgroups(): %.200s", strerror(errno));
925 /* Initialize configuration options to their default values. */
926 initialize_server_options(&options);
928 /* Parse command-line arguments. */
929 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
932 options.address_family = AF_INET;
935 options.address_family = AF_INET6;
938 config_file_name = optarg;
941 if (debug_flag == 0) {
943 options.log_level = SYSLOG_LEVEL_DEBUG1;
944 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
967 options.log_level = SYSLOG_LEVEL_QUIET;
970 options.server_key_bits = atoi(optarg);
973 options.ports_from_cmdline = 1;
974 if (options.num_ports >= MAX_PORTS) {
975 fprintf(stderr, "too many ports.\n");
978 options.ports[options.num_ports++] = a2port(optarg);
979 if (options.ports[options.num_ports-1] == 0) {
980 fprintf(stderr, "Bad port number.\n");
985 if ((options.login_grace_time = convtime(optarg)) == -1) {
986 fprintf(stderr, "Invalid login grace time.\n");
991 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
992 fprintf(stderr, "Invalid key regeneration interval.\n");
997 if (options.num_host_key_files >= MAX_HOSTKEYS) {
998 fprintf(stderr, "too many host keys.\n");
1001 options.host_key_files[options.num_host_key_files++] = optarg;
1007 utmp_len = atoi(optarg);
1008 if (utmp_len > MAXHOSTNAMELEN) {
1009 fprintf(stderr, "Invalid utmp length.\n");
1014 line = xstrdup(optarg);
1015 if (process_server_config_line(&options, line,
1016 "command-line", 0) != 0)
1026 if (rexeced_flag || inetd_flag)
1028 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1029 fatal("sshd re-exec requires execution with an absolute path");
1031 closefrom(REEXEC_MIN_FREE_FD);
1033 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1035 SSLeay_add_all_algorithms();
1038 * Force logging to stderr until we have loaded the private host
1039 * key (unless started from inetd)
1041 log_init(__progname,
1042 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1043 SYSLOG_LEVEL_INFO : options.log_level,
1044 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1045 SYSLOG_FACILITY_AUTH : options.log_facility,
1046 log_stderr || !inetd_flag);
1049 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1050 * root's environment
1052 if (getenv("KRB5CCNAME") != NULL)
1053 unsetenv("KRB5CCNAME");
1056 /* Cray can define user privs drop all privs now!
1057 * Not needed on PRIV_SU systems!
1064 sensitive_data.server_key = NULL;
1065 sensitive_data.ssh1_host_key = NULL;
1066 sensitive_data.have_ssh1_key = 0;
1067 sensitive_data.have_ssh2_key = 0;
1069 /* Fetch our configuration */
1072 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1074 load_server_config(config_file_name, &cfg);
1076 parse_server_config(&options,
1077 rexeced_flag ? "rexec" : config_file_name, &cfg);
1082 /* Fill in default values for those options not explicitly set. */
1083 fill_default_server_options(&options);
1085 /* set default channel AF */
1086 channel_set_af(options.address_family);
1088 /* Check that there are no remaining arguments. */
1090 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1094 debug("sshd version %.100s", SSH_RELEASE);
1096 /* load private host keys */
1097 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1099 for (i = 0; i < options.num_host_key_files; i++)
1100 sensitive_data.host_keys[i] = NULL;
1102 for (i = 0; i < options.num_host_key_files; i++) {
1103 key = key_load_private(options.host_key_files[i], "", NULL);
1104 sensitive_data.host_keys[i] = key;
1106 error("Could not load host key: %s",
1107 options.host_key_files[i]);
1108 sensitive_data.host_keys[i] = NULL;
1111 switch (key->type) {
1113 sensitive_data.ssh1_host_key = key;
1114 sensitive_data.have_ssh1_key = 1;
1118 sensitive_data.have_ssh2_key = 1;
1121 debug("private host key: #%d type %d %s", i, key->type,
1124 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1125 logit("Disabling protocol version 1. Could not load host key");
1126 options.protocol &= ~SSH_PROTO_1;
1128 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1129 logit("Disabling protocol version 2. Could not load host key");
1130 options.protocol &= ~SSH_PROTO_2;
1132 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1133 logit("sshd: no hostkeys available -- exiting.");
1137 /* Check certain values for sanity. */
1138 if (options.protocol & SSH_PROTO_1) {
1139 if (options.server_key_bits < 512 ||
1140 options.server_key_bits > 32768) {
1141 fprintf(stderr, "Bad server key size.\n");
1145 * Check that server and host key lengths differ sufficiently. This
1146 * is necessary to make double encryption work with rsaref. Oh, I
1147 * hate software patents. I dont know if this can go? Niels
1149 if (options.server_key_bits >
1150 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1151 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1152 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1153 SSH_KEY_BITS_RESERVED) {
1154 options.server_key_bits =
1155 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1156 SSH_KEY_BITS_RESERVED;
1157 debug("Forcing server key to %d bits to make it differ from host key.",
1158 options.server_key_bits);
1166 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1167 fatal("Privilege separation user %s does not exist",
1169 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1170 (S_ISDIR(st.st_mode) == 0))
1171 fatal("Missing privilege separation directory: %s",
1172 _PATH_PRIVSEP_CHROOT_DIR);
1175 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1176 (st.st_uid != getuid () ||
1177 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1179 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1181 fatal("%s must be owned by root and not group or "
1182 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1185 /* Configuration looks good, so exit if in test mode. */
1190 * Clear out any supplemental groups we may have inherited. This
1191 * prevents inadvertent creation of files with bad modes (in the
1192 * portable version at least, it's certainly possible for PAM
1193 * to create a file, and we can't control the code in every
1194 * module which might be used).
1196 if (setgroups(0, NULL) < 0)
1197 debug("setgroups() failed: %.200s", strerror(errno));
1200 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1201 for (i = 0; i < rexec_argc; i++) {
1202 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1203 rexec_argv[i] = saved_argv[i];
1205 rexec_argv[rexec_argc] = "-R";
1206 rexec_argv[rexec_argc + 1] = NULL;
1209 /* Initialize the log (it is reinitialized below in case we forked). */
1210 if (debug_flag && (!inetd_flag || rexeced_flag))
1212 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1215 * If not in debugging mode, and not started from inetd, disconnect
1216 * from the controlling terminal, and fork. The original process
1219 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1222 #endif /* TIOCNOTTY */
1223 if (daemon(0, 0) < 0)
1224 fatal("daemon() failed: %.200s", strerror(errno));
1226 /* Disconnect from the controlling tty. */
1228 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1230 (void) ioctl(fd, TIOCNOTTY, NULL);
1233 #endif /* TIOCNOTTY */
1235 /* Reinitialize the log (because of the fork above). */
1236 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1238 /* Initialize the random number generator. */
1241 /* Chdir to the root directory so that the current disk can be
1242 unmounted if desired. */
1245 /* ignore SIGPIPE */
1246 signal(SIGPIPE, SIG_IGN);
1248 /* Start listening for a socket, unless started from inetd. */
1254 close(REEXEC_CONFIG_PASS_FD);
1255 sock_in = sock_out = dup(STDIN_FILENO);
1257 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1258 close(REEXEC_STARTUP_PIPE_FD);
1261 sock_in = dup(STDIN_FILENO);
1262 sock_out = dup(STDOUT_FILENO);
1265 * We intentionally do not close the descriptors 0, 1, and 2
1266 * as our code for setting the descriptors won't work if
1267 * ttyfd happens to be one of those.
1269 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1270 dup2(fd, STDIN_FILENO);
1271 dup2(fd, STDOUT_FILENO);
1272 if (fd > STDOUT_FILENO)
1275 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1276 if ((options.protocol & SSH_PROTO_1) &&
1277 sensitive_data.server_key == NULL)
1278 generate_ephemeral_server_key();
1280 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1281 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1283 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1284 fatal("Too many listen sockets. "
1285 "Enlarge MAX_LISTEN_SOCKS");
1286 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1287 ntop, sizeof(ntop), strport, sizeof(strport),
1288 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1289 error("getnameinfo failed: %.100s",
1290 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1294 /* Create socket for listening. */
1295 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1297 if (listen_sock < 0) {
1298 /* kernel may not support ipv6 */
1299 verbose("socket: %.100s", strerror(errno));
1302 if (set_nonblock(listen_sock) == -1) {
1307 * Set socket options.
1308 * Allow local port reuse in TIME_WAIT.
1310 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1311 &on, sizeof(on)) == -1)
1312 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1314 debug("Bind to port %s on %s.", strport, ntop);
1316 /* Bind the socket to the desired port. */
1317 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1319 error("Bind to port %s on %s failed: %.200s.",
1320 strport, ntop, strerror(errno));
1324 listen_socks[num_listen_socks] = listen_sock;
1327 /* Start listening on the port. */
1328 logit("Server listening on %s port %s.", ntop, strport);
1329 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1330 fatal("listen: %.100s", strerror(errno));
1333 freeaddrinfo(options.listen_addrs);
1335 if (!num_listen_socks)
1336 fatal("Cannot bind any address.");
1338 if (options.protocol & SSH_PROTO_1)
1339 generate_ephemeral_server_key();
1342 * Arrange to restart on SIGHUP. The handler needs
1345 signal(SIGHUP, sighup_handler);
1347 signal(SIGTERM, sigterm_handler);
1348 signal(SIGQUIT, sigterm_handler);
1350 /* Arrange SIGCHLD to be caught. */
1351 signal(SIGCHLD, main_sigchld_handler);
1353 /* Write out the pid file after the sigterm handler is setup */
1356 * Record our pid in /var/run/sshd.pid to make it
1357 * easier to kill the correct sshd. We don't want to
1358 * do this before the bind above because the bind will
1359 * fail if there already is a daemon, and this will
1360 * overwrite any old pid in the file.
1362 f = fopen(options.pid_file, "wb");
1364 error("Couldn't create pid file \"%s\": %s",
1365 options.pid_file, strerror(errno));
1367 fprintf(f, "%ld\n", (long) getpid());
1372 /* setup fd set for listen */
1375 for (i = 0; i < num_listen_socks; i++)
1376 if (listen_socks[i] > maxfd)
1377 maxfd = listen_socks[i];
1378 /* pipes connected to unauthenticated childs */
1379 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1380 for (i = 0; i < options.max_startups; i++)
1381 startup_pipes[i] = -1;
1384 * Stay listening for connections until the system crashes or
1385 * the daemon is killed with a signal.
1388 if (received_sighup)
1392 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1393 fdset = (fd_set *)xmalloc(fdsetsz);
1394 memset(fdset, 0, fdsetsz);
1396 for (i = 0; i < num_listen_socks; i++)
1397 FD_SET(listen_socks[i], fdset);
1398 for (i = 0; i < options.max_startups; i++)
1399 if (startup_pipes[i] != -1)
1400 FD_SET(startup_pipes[i], fdset);
1402 /* Wait in select until there is a connection. */
1403 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1404 if (ret < 0 && errno != EINTR)
1405 error("select: %.100s", strerror(errno));
1406 if (received_sigterm) {
1407 logit("Received signal %d; terminating.",
1408 (int) received_sigterm);
1409 close_listen_socks();
1410 unlink(options.pid_file);
1413 if (key_used && key_do_regen) {
1414 generate_ephemeral_server_key();
1421 for (i = 0; i < options.max_startups; i++)
1422 if (startup_pipes[i] != -1 &&
1423 FD_ISSET(startup_pipes[i], fdset)) {
1425 * the read end of the pipe is ready
1426 * if the child has closed the pipe
1427 * after successful authentication
1428 * or if the child has died
1430 close(startup_pipes[i]);
1431 startup_pipes[i] = -1;
1434 for (i = 0; i < num_listen_socks; i++) {
1435 if (!FD_ISSET(listen_socks[i], fdset))
1437 fromlen = sizeof(from);
1438 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1441 if (errno != EINTR && errno != EWOULDBLOCK)
1442 error("accept: %.100s", strerror(errno));
1445 if (unset_nonblock(newsock) == -1) {
1449 if (drop_connection(startups) == 1) {
1450 debug("drop connection #%d", startups);
1454 if (pipe(startup_p) == -1) {
1459 if (rexec_flag && socketpair(AF_UNIX,
1460 SOCK_STREAM, 0, config_s) == -1) {
1461 error("reexec socketpair: %s",
1464 close(startup_p[0]);
1465 close(startup_p[1]);
1469 for (j = 0; j < options.max_startups; j++)
1470 if (startup_pipes[j] == -1) {
1471 startup_pipes[j] = startup_p[0];
1472 if (maxfd < startup_p[0])
1473 maxfd = startup_p[0];
1479 * Got connection. Fork a child to handle it, unless
1480 * we are in debugging mode.
1484 * In debugging mode. Close the listening
1485 * socket, and start processing the
1486 * connection without forking.
1488 debug("Server will not fork when running in debugging mode.");
1489 close_listen_socks();
1492 close(startup_p[0]);
1493 close(startup_p[1]);
1497 send_rexec_state(config_s[0],
1504 * Normal production daemon. Fork, and have
1505 * the child process the connection. The
1506 * parent continues listening.
1508 if ((pid = fork()) == 0) {
1510 * Child. Close the listening and max_startup
1511 * sockets. Start using the accepted socket.
1512 * Reinitialize logging (since our pid has
1513 * changed). We break out of the loop to handle
1516 startup_pipe = startup_p[1];
1517 close_startup_pipes();
1518 close_listen_socks();
1521 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1528 /* Parent. Stay in the loop. */
1530 error("fork: %.100s", strerror(errno));
1532 debug("Forked child %ld.", (long)pid);
1534 close(startup_p[1]);
1537 send_rexec_state(config_s[0], &cfg);
1542 /* Mark that the key has been used (it was "given" to the child). */
1543 if ((options.protocol & SSH_PROTO_1) &&
1545 /* Schedule server key regeneration alarm. */
1546 signal(SIGALRM, key_regeneration_alarm);
1547 alarm(options.key_regeneration_time);
1553 /* Close the new socket (the child is now taking care of it). */
1556 /* child process check (or debug mode) */
1557 if (num_listen_socks < 0)
1562 /* This is the child processing a new connection. */
1563 setproctitle("%s", "[accepted]");
1566 * Create a new session and process group since the 4.4BSD
1567 * setlogin() affects the entire process group. We don't
1568 * want the child to be able to affect the parent.
1570 #if !defined(SSHD_ACQUIRES_CTTY)
1572 * If setsid is called, on some platforms sshd will later acquire a
1573 * controlling terminal which will result in "could not set
1574 * controlling tty" errors.
1576 if (!debug_flag && !inetd_flag && setsid() < 0)
1577 error("setsid: %.100s", strerror(errno));
1583 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1584 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1585 dup2(newsock, STDIN_FILENO);
1586 dup2(STDIN_FILENO, STDOUT_FILENO);
1587 if (startup_pipe == -1)
1588 close(REEXEC_STARTUP_PIPE_FD);
1590 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1592 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1594 if (startup_pipe != -1)
1595 close(startup_pipe);
1597 execv(rexec_argv[0], rexec_argv);
1599 /* Reexec has failed, fall back and continue */
1600 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1601 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1602 log_init(__progname, options.log_level,
1603 options.log_facility, log_stderr);
1606 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1608 close(REEXEC_CONFIG_PASS_FD);
1609 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1610 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1611 dup2(fd, STDIN_FILENO);
1612 dup2(fd, STDOUT_FILENO);
1613 if (fd > STDERR_FILENO)
1616 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1617 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1621 * Disable the key regeneration alarm. We will not regenerate the
1622 * key since we are no longer in a position to give it to anyone. We
1623 * will not restart on SIGHUP since it no longer makes sense.
1626 signal(SIGALRM, SIG_DFL);
1627 signal(SIGHUP, SIG_DFL);
1628 signal(SIGTERM, SIG_DFL);
1629 signal(SIGQUIT, SIG_DFL);
1630 signal(SIGCHLD, SIG_DFL);
1631 signal(SIGINT, SIG_DFL);
1635 * Initialize the resolver. This may not happen automatically
1636 * before privsep chroot().
1638 if ((_res.options & RES_INIT) == 0) {
1639 debug("res_init()");
1644 * Force GSS-API to parse its configuration and load any
1645 * mechanism plugins.
1649 OM_uint32 minor_status;
1650 gss_indicate_mechs(&minor_status, &mechs);
1651 gss_release_oid_set(&minor_status, &mechs);
1657 * Register our connection. This turns encryption off because we do
1660 packet_set_connection(sock_in, sock_out);
1661 packet_set_server();
1663 /* Set SO_KEEPALIVE if requested. */
1664 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1665 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1666 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1668 if ((remote_port = get_remote_port()) < 0) {
1669 debug("get_remote_port failed");
1672 remote_ip = get_remote_ipaddr();
1674 #ifdef SSH_AUDIT_EVENTS
1675 audit_connection_from(remote_ip, remote_port);
1678 /* Check whether logins are denied from this host. */
1679 if (packet_connection_is_on_socket()) {
1680 struct request_info req;
1682 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1685 if (!hosts_access(&req)) {
1686 debug("Connection refused by tcp wrapper");
1689 fatal("libwrap refuse returns");
1692 #endif /* LIBWRAP */
1694 /* Log the connection. */
1695 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1698 * We don\'t want to listen forever unless the other side
1699 * successfully authenticates itself. So we set up an alarm which is
1700 * cleared after successful authentication. A limit of zero
1701 * indicates no limit. Note that we don\'t set the alarm in debugging
1702 * mode; it is just annoying to have the server exit just when you
1703 * are about to discover the bug.
1705 signal(SIGALRM, grace_alarm_handler);
1707 alarm(options.login_grace_time);
1709 sshd_exchange_identification(sock_in, sock_out);
1711 packet_set_nonblocking();
1713 /* allocate authentication context */
1714 authctxt = xmalloc(sizeof(*authctxt));
1715 memset(authctxt, 0, sizeof(*authctxt));
1717 authctxt->loginmsg = &loginmsg;
1719 /* XXX global for cleanup, access from other modules */
1720 the_authctxt = authctxt;
1722 /* prepare buffer to collect messages to display to user after login */
1723 buffer_init(&loginmsg);
1726 if (privsep_preauth(authctxt) == 1)
1729 /* perform the key exchange */
1730 /* authenticate user and start session */
1733 do_authentication2(authctxt);
1736 do_authentication(authctxt);
1739 * If we use privilege separation, the unprivileged child transfers
1740 * the current keystate and exits
1743 mm_send_keystate(pmonitor);
1748 #ifdef SSH_AUDIT_EVENTS
1749 audit_event(SSH_AUTH_SUCCESS);
1753 * In privilege separation, we fork another child and prepare
1754 * file descriptor passing.
1757 privsep_postauth(authctxt);
1758 /* the monitor process [priv] will not return */
1760 destroy_sensitive_data();
1763 /* Start session. */
1764 do_authenticated(authctxt);
1766 /* The connection has been terminated. */
1767 verbose("Closing connection to %.100s", remote_ip);
1770 if (options.use_pam)
1772 #endif /* USE_PAM */
1774 #ifdef SSH_AUDIT_EVENTS
1775 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1787 * Decrypt session_key_int using our private server key and private host key
1788 * (key with larger modulus first).
1791 ssh1_session_key(BIGNUM *session_key_int)
1795 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1796 /* Server key has bigger modulus. */
1797 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1798 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1799 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1800 get_remote_ipaddr(),
1801 BN_num_bits(sensitive_data.server_key->rsa->n),
1802 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1803 SSH_KEY_BITS_RESERVED);
1805 if (rsa_private_decrypt(session_key_int, session_key_int,
1806 sensitive_data.server_key->rsa) <= 0)
1808 if (rsa_private_decrypt(session_key_int, session_key_int,
1809 sensitive_data.ssh1_host_key->rsa) <= 0)
1812 /* Host key has bigger modulus (or they are equal). */
1813 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1814 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1815 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1816 get_remote_ipaddr(),
1817 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1818 BN_num_bits(sensitive_data.server_key->rsa->n),
1819 SSH_KEY_BITS_RESERVED);
1821 if (rsa_private_decrypt(session_key_int, session_key_int,
1822 sensitive_data.ssh1_host_key->rsa) < 0)
1824 if (rsa_private_decrypt(session_key_int, session_key_int,
1825 sensitive_data.server_key->rsa) < 0)
1838 BIGNUM *session_key_int;
1839 u_char session_key[SSH_SESSION_KEY_LENGTH];
1841 u_int cipher_type, auth_mask, protocol_flags;
1845 * Generate check bytes that the client must send back in the user
1846 * packet in order for it to be accepted; this is used to defy ip
1847 * spoofing attacks. Note that this only works against somebody
1848 * doing IP spoofing from a remote machine; any machine on the local
1849 * network can still see outgoing packets and catch the random
1850 * cookie. This only affects rhosts authentication, and this is one
1851 * of the reasons why it is inherently insecure.
1853 for (i = 0; i < 8; i++) {
1856 cookie[i] = rnd & 0xff;
1861 * Send our public key. We include in the packet 64 bits of random
1862 * data that must be matched in the reply in order to prevent IP
1865 packet_start(SSH_SMSG_PUBLIC_KEY);
1866 for (i = 0; i < 8; i++)
1867 packet_put_char(cookie[i]);
1869 /* Store our public server RSA key. */
1870 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1871 packet_put_bignum(sensitive_data.server_key->rsa->e);
1872 packet_put_bignum(sensitive_data.server_key->rsa->n);
1874 /* Store our public host RSA key. */
1875 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1876 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1877 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1879 /* Put protocol flags. */
1880 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1882 /* Declare which ciphers we support. */
1883 packet_put_int(cipher_mask_ssh1(0));
1885 /* Declare supported authentication types. */
1887 if (options.rhosts_rsa_authentication)
1888 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1889 if (options.rsa_authentication)
1890 auth_mask |= 1 << SSH_AUTH_RSA;
1891 if (options.challenge_response_authentication == 1)
1892 auth_mask |= 1 << SSH_AUTH_TIS;
1893 if (options.password_authentication)
1894 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1895 packet_put_int(auth_mask);
1897 /* Send the packet and wait for it to be sent. */
1899 packet_write_wait();
1901 debug("Sent %d bit server key and %d bit host key.",
1902 BN_num_bits(sensitive_data.server_key->rsa->n),
1903 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1905 /* Read clients reply (cipher type and session key). */
1906 packet_read_expect(SSH_CMSG_SESSION_KEY);
1908 /* Get cipher type and check whether we accept this. */
1909 cipher_type = packet_get_char();
1911 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1912 packet_disconnect("Warning: client selects unsupported cipher.");
1914 /* Get check bytes from the packet. These must match those we
1915 sent earlier with the public key packet. */
1916 for (i = 0; i < 8; i++)
1917 if (cookie[i] != packet_get_char())
1918 packet_disconnect("IP Spoofing check bytes do not match.");
1920 debug("Encryption type: %.200s", cipher_name(cipher_type));
1922 /* Get the encrypted integer. */
1923 if ((session_key_int = BN_new()) == NULL)
1924 fatal("do_ssh1_kex: BN_new failed");
1925 packet_get_bignum(session_key_int);
1927 protocol_flags = packet_get_int();
1928 packet_set_protocol_flags(protocol_flags);
1931 /* Decrypt session_key_int using host/server keys */
1932 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1935 * Extract session key from the decrypted integer. The key is in the
1936 * least significant 256 bits of the integer; the first byte of the
1937 * key is in the highest bits.
1940 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1941 len = BN_num_bytes(session_key_int);
1942 if (len < 0 || (u_int)len > sizeof(session_key)) {
1943 error("do_connection: bad session key len from %s: "
1944 "session_key_int %d > sizeof(session_key) %lu",
1945 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1948 memset(session_key, 0, sizeof(session_key));
1949 BN_bn2bin(session_key_int,
1950 session_key + sizeof(session_key) - len);
1952 derive_ssh1_session_id(
1953 sensitive_data.ssh1_host_key->rsa->n,
1954 sensitive_data.server_key->rsa->n,
1955 cookie, session_id);
1957 * Xor the first 16 bytes of the session key with the
1960 for (i = 0; i < 16; i++)
1961 session_key[i] ^= session_id[i];
1965 int bytes = BN_num_bytes(session_key_int);
1966 u_char *buf = xmalloc(bytes);
1969 logit("do_connection: generating a fake encryption key");
1970 BN_bn2bin(session_key_int, buf);
1972 MD5_Update(&md, buf, bytes);
1973 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1974 MD5_Final(session_key, &md);
1976 MD5_Update(&md, session_key, 16);
1977 MD5_Update(&md, buf, bytes);
1978 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1979 MD5_Final(session_key + 16, &md);
1980 memset(buf, 0, bytes);
1982 for (i = 0; i < 16; i++)
1983 session_id[i] = session_key[i] ^ session_key[i + 16];
1985 /* Destroy the private and public keys. No longer. */
1986 destroy_sensitive_data();
1989 mm_ssh1_session_id(session_id);
1991 /* Destroy the decrypted integer. It is no longer needed. */
1992 BN_clear_free(session_key_int);
1994 /* Set the session key. From this on all communications will be encrypted. */
1995 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1997 /* Destroy our copy of the session key. It is no longer needed. */
1998 memset(session_key, 0, sizeof(session_key));
2000 debug("Received session key; encryption turned on.");
2002 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2003 packet_start(SSH_SMSG_SUCCESS);
2005 packet_write_wait();
2009 * SSH2 key exchange: diffie-hellman-group1-sha1
2016 if (options.ciphers != NULL) {
2017 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2018 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2020 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2021 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2022 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2023 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2025 if (options.macs != NULL) {
2026 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2027 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2029 if (options.compression == COMP_NONE) {
2030 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2031 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2032 } else if (options.compression == COMP_DELAYED) {
2033 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2034 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2037 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2039 /* start key exchange */
2040 kex = kex_setup(myproposal);
2041 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2042 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2043 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2045 kex->client_version_string=client_version_string;
2046 kex->server_version_string=server_version_string;
2047 kex->load_host_key=&get_hostkey_by_type;
2048 kex->host_key_index=&get_hostkey_index;
2052 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2054 session_id2 = kex->session_id;
2055 session_id2_len = kex->session_id_len;
2058 /* send 1st encrypted/maced/compressed message */
2059 packet_start(SSH2_MSG_IGNORE);
2060 packet_put_cstring("markus");
2062 packet_write_wait();
2067 /* server specific fatal cleanup */
2072 do_cleanup(the_authctxt);
2073 #ifdef SSH_AUDIT_EVENTS
2074 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2075 if (!use_privsep || mm_is_monitor())
2076 audit_event(SSH_CONNECTION_ABANDON);