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.
46 #include <sys/types.h>
47 #ifdef HAVE_SYS_STAT_H
48 # include <sys/stat.h>
50 #include <sys/ioctl.h>
58 #include <openssl/dh.h>
59 #include <openssl/bn.h>
60 #include <openssl/md5.h>
61 #include <openssl/rand.h>
62 #ifdef HAVE_SECUREWARE
63 #include <sys/security.h>
84 #include "myproposal.h"
86 #include "pathnames.h"
95 #include "monitor_mm.h"
97 #include "monitor_wrap.h"
98 #include "monitor_fdpass.h"
103 int allow_severity = LOG_INFO;
104 int deny_severity = LOG_WARNING;
112 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
113 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
114 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
115 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
117 extern char *__progname;
119 /* Server configuration options. */
120 ServerOptions options;
122 /* Name of the server configuration file. */
123 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
126 * Debug mode flag. This can be set on the command line. If debug
127 * mode is enabled, extra debugging output will be sent to the system
128 * log, the daemon will not go to background, and will exit after processing
129 * the first connection.
133 /* Flag indicating that the daemon should only test the configuration and keys. */
136 /* Flag indicating that the daemon is being started from inetd. */
139 /* Flag indicating that sshd should not detach and become a daemon. */
140 int no_daemon_flag = 0;
142 /* debug goes to stderr unless inetd_flag is set */
145 /* Saved arguments to main(). */
150 int rexeced_flag = 0;
156 * The sockets that the server is listening; this is used in the SIGHUP
159 #define MAX_LISTEN_SOCKS 16
160 int listen_socks[MAX_LISTEN_SOCKS];
161 int num_listen_socks = 0;
164 * the client's version string, passed by sshd2 in compat mode. if != NULL,
165 * sshd will skip the version-number exchange
167 char *client_version_string = NULL;
168 char *server_version_string = NULL;
170 /* for rekeying XXX fixme */
174 * Any really sensitive data in the application is contained in this
175 * structure. The idea is that this structure could be locked into memory so
176 * that the pages do not get written into swap. However, there are some
177 * problems. The private key contains BIGNUMs, and we do not (in principle)
178 * have access to the internals of them, and locking just the structure is
179 * not very useful. Currently, memory locking is not implemented.
182 Key *server_key; /* ephemeral server key */
183 Key *ssh1_host_key; /* ssh1 host key */
184 Key **host_keys; /* all private host keys */
187 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
191 * Flag indicating whether the RSA server key needs to be regenerated.
192 * Is set in the SIGALRM handler and cleared when the key is regenerated.
194 static volatile sig_atomic_t key_do_regen = 0;
196 /* This is set to true when a signal is received. */
197 static volatile sig_atomic_t received_sighup = 0;
198 static volatile sig_atomic_t received_sigterm = 0;
200 /* session identifier, used by RSA-auth */
201 u_char session_id[16];
204 u_char *session_id2 = NULL;
205 u_int session_id2_len = 0;
207 /* record remote hostname or ip */
208 u_int utmp_len = MAXHOSTNAMELEN;
210 /* options.max_startup sized array of fd ints */
211 int *startup_pipes = NULL;
212 int startup_pipe; /* in child */
214 /* variables used for privilege separation */
216 struct monitor *pmonitor = NULL;
218 /* global authentication context */
219 Authctxt *the_authctxt = NULL;
221 /* message to be displayed after login */
224 /* Prototypes for various functions defined later in this file. */
225 void destroy_sensitive_data(void);
226 void demote_sensitive_data(void);
228 static void do_ssh1_kex(void);
229 static void do_ssh2_kex(void);
232 * Close all listening sockets
235 close_listen_socks(void)
239 for (i = 0; i < num_listen_socks; i++)
240 close(listen_socks[i]);
241 num_listen_socks = -1;
245 close_startup_pipes(void)
250 for (i = 0; i < options.max_startups; i++)
251 if (startup_pipes[i] != -1)
252 close(startup_pipes[i]);
256 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
257 * the effect is to reread the configuration file (and to regenerate
261 sighup_handler(int sig)
263 int save_errno = errno;
266 signal(SIGHUP, sighup_handler);
271 * Called from the main program after receiving SIGHUP.
272 * Restarts the server.
277 logit("Received SIGHUP; restarting.");
278 close_listen_socks();
279 close_startup_pipes();
280 execv(saved_argv[0], saved_argv);
281 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
287 * Generic signal handler for terminating signals in the master daemon.
290 sigterm_handler(int sig)
292 received_sigterm = sig;
296 * SIGCHLD handler. This is called whenever a child dies. This will then
297 * reap any zombies left by exited children.
300 main_sigchld_handler(int sig)
302 int save_errno = errno;
306 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
307 (pid < 0 && errno == EINTR))
310 signal(SIGCHLD, main_sigchld_handler);
315 * Signal handler for the alarm after the login grace period has expired.
318 grace_alarm_handler(int sig)
320 /* XXX no idea how fix this signal handler */
322 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
323 kill(pmonitor->m_pid, SIGALRM);
325 /* Log error and exit. */
326 fatal("Timeout before authentication for %s", get_remote_ipaddr());
330 * Signal handler for the key regeneration alarm. Note that this
331 * alarm only occurs in the daemon waiting for connections, and it does not
332 * do anything with the private key or random state before forking.
333 * Thus there should be no concurrency control/asynchronous execution
337 generate_ephemeral_server_key(void)
342 verbose("Generating %s%d bit RSA key.",
343 sensitive_data.server_key ? "new " : "", options.server_key_bits);
344 if (sensitive_data.server_key != NULL)
345 key_free(sensitive_data.server_key);
346 sensitive_data.server_key = key_generate(KEY_RSA1,
347 options.server_key_bits);
348 verbose("RSA key generation complete.");
350 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
353 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
360 key_regeneration_alarm(int sig)
362 int save_errno = errno;
364 signal(SIGALRM, SIG_DFL);
370 sshd_exchange_identification(int sock_in, int sock_out)
374 int remote_major, remote_minor;
377 char buf[256]; /* Must not be larger than remote_version. */
378 char remote_version[256]; /* Must be at least as big as buf. */
380 if ((options.protocol & SSH_PROTO_1) &&
381 (options.protocol & SSH_PROTO_2)) {
382 major = PROTOCOL_MAJOR_1;
384 } else if (options.protocol & SSH_PROTO_2) {
385 major = PROTOCOL_MAJOR_2;
386 minor = PROTOCOL_MINOR_2;
388 major = PROTOCOL_MAJOR_1;
389 minor = PROTOCOL_MINOR_1;
391 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
392 server_version_string = xstrdup(buf);
394 /* Send our protocol version identification. */
395 if (atomicio(vwrite, sock_out, server_version_string,
396 strlen(server_version_string))
397 != strlen(server_version_string)) {
398 logit("Could not write ident string to %s", get_remote_ipaddr());
402 /* Read other sides version identification. */
403 memset(buf, 0, sizeof(buf));
404 for (i = 0; i < sizeof(buf) - 1; i++) {
405 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
406 logit("Did not receive identification string from %s",
407 get_remote_ipaddr());
410 if (buf[i] == '\r') {
412 /* Kludge for F-Secure Macintosh < 1.0.2 */
414 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
418 if (buf[i] == '\n') {
423 buf[sizeof(buf) - 1] = 0;
424 client_version_string = xstrdup(buf);
427 * Check that the versions match. In future this might accept
428 * several versions and set appropriate flags to handle them.
430 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
431 &remote_major, &remote_minor, remote_version) != 3) {
432 s = "Protocol mismatch.\n";
433 (void) atomicio(vwrite, sock_out, s, strlen(s));
436 logit("Bad protocol version identification '%.100s' from %s",
437 client_version_string, get_remote_ipaddr());
440 debug("Client protocol version %d.%d; client software version %.100s",
441 remote_major, remote_minor, remote_version);
443 compat_datafellows(remote_version);
445 if (datafellows & SSH_BUG_PROBE) {
446 logit("probed from %s with %s. Don't panic.",
447 get_remote_ipaddr(), client_version_string);
451 if (datafellows & SSH_BUG_SCANNER) {
452 logit("scanned from %s with %s. Don't panic.",
453 get_remote_ipaddr(), client_version_string);
458 switch (remote_major) {
460 if (remote_minor == 99) {
461 if (options.protocol & SSH_PROTO_2)
467 if (!(options.protocol & SSH_PROTO_1)) {
471 if (remote_minor < 3) {
472 packet_disconnect("Your ssh version is too old and "
473 "is no longer supported. Please install a newer version.");
474 } else if (remote_minor == 3) {
475 /* note that this disables agent-forwarding */
480 if (options.protocol & SSH_PROTO_2) {
489 chop(server_version_string);
490 debug("Local version string %.200s", server_version_string);
493 s = "Protocol major versions differ.\n";
494 (void) atomicio(vwrite, sock_out, s, strlen(s));
497 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
499 server_version_string, client_version_string);
504 /* Destroy the host and server keys. They will no longer be needed. */
506 destroy_sensitive_data(void)
510 if (sensitive_data.server_key) {
511 key_free(sensitive_data.server_key);
512 sensitive_data.server_key = NULL;
514 for (i = 0; i < options.num_host_key_files; i++) {
515 if (sensitive_data.host_keys[i]) {
516 key_free(sensitive_data.host_keys[i]);
517 sensitive_data.host_keys[i] = NULL;
520 sensitive_data.ssh1_host_key = NULL;
521 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
524 /* Demote private to public keys for network child */
526 demote_sensitive_data(void)
531 if (sensitive_data.server_key) {
532 tmp = key_demote(sensitive_data.server_key);
533 key_free(sensitive_data.server_key);
534 sensitive_data.server_key = tmp;
537 for (i = 0; i < options.num_host_key_files; i++) {
538 if (sensitive_data.host_keys[i]) {
539 tmp = key_demote(sensitive_data.host_keys[i]);
540 key_free(sensitive_data.host_keys[i]);
541 sensitive_data.host_keys[i] = tmp;
542 if (tmp->type == KEY_RSA1)
543 sensitive_data.ssh1_host_key = tmp;
547 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
551 privsep_preauth_child(void)
558 /* Enable challenge-response authentication for privilege separation */
559 privsep_challenge_enable();
561 for (i = 0; i < 256; i++)
562 rnd[i] = arc4random();
563 RAND_seed(rnd, sizeof(rnd));
565 /* Demote the private keys to public keys. */
566 demote_sensitive_data();
568 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
569 fatal("Privilege separation user %s does not exist",
571 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
574 /* Change our root directory */
575 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
576 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
578 if (chdir("/") == -1)
579 fatal("chdir(\"/\"): %s", strerror(errno));
581 /* Drop our privileges */
582 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
585 /* XXX not ready, too heavy after chroot */
586 do_setusercontext(pw);
588 gidset[0] = pw->pw_gid;
589 if (setgroups(1, gidset) < 0)
590 fatal("setgroups: %.100s", strerror(errno));
591 permanently_set_uid(pw);
596 privsep_preauth(Authctxt *authctxt)
601 /* Set up unprivileged child process to deal with network data */
602 pmonitor = monitor_init();
603 /* Store a pointer to the kex for later rekeying */
604 pmonitor->m_pkex = &xxx_kex;
608 fatal("fork of unprivileged child failed");
609 } else if (pid != 0) {
610 debug2("Network child is on pid %ld", (long)pid);
612 close(pmonitor->m_recvfd);
613 pmonitor->m_pid = pid;
614 monitor_child_preauth(authctxt, pmonitor);
615 close(pmonitor->m_sendfd);
618 monitor_sync(pmonitor);
620 /* Wait for the child's exit status */
621 while (waitpid(pid, &status, 0) < 0)
628 close(pmonitor->m_sendfd);
630 /* Demote the child */
631 if (getuid() == 0 || geteuid() == 0)
632 privsep_preauth_child();
633 setproctitle("%s", "[net]");
639 privsep_postauth(Authctxt *authctxt)
641 #ifdef DISABLE_FD_PASSING
644 if (authctxt->pw->pw_uid == 0 || options.use_login) {
646 /* File descriptor passing is broken or root login */
651 /* New socket pair */
652 monitor_reinit(pmonitor);
654 pmonitor->m_pid = fork();
655 if (pmonitor->m_pid == -1)
656 fatal("fork of unprivileged child failed");
657 else if (pmonitor->m_pid != 0) {
658 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
659 close(pmonitor->m_recvfd);
660 buffer_clear(&loginmsg);
661 monitor_child_postauth(pmonitor);
667 close(pmonitor->m_sendfd);
669 /* Demote the private keys to public keys. */
670 demote_sensitive_data();
672 /* Drop privileges */
673 do_setusercontext(authctxt->pw);
676 /* It is safe now to apply the key state */
677 monitor_apply_keystate(pmonitor);
680 * Tell the packet layer that authentication was successful, since
681 * this information is not part of the key state.
683 packet_set_authenticated();
687 list_hostkey_types(void)
695 for (i = 0; i < options.num_host_key_files; i++) {
696 Key *key = sensitive_data.host_keys[i];
702 if (buffer_len(&b) > 0)
703 buffer_append(&b, ",", 1);
704 p = key_ssh_name(key);
705 buffer_append(&b, p, strlen(p));
709 buffer_append(&b, "\0", 1);
710 ret = xstrdup(buffer_ptr(&b));
712 debug("list_hostkey_types: %s", ret);
717 get_hostkey_by_type(int type)
721 for (i = 0; i < options.num_host_key_files; i++) {
722 Key *key = sensitive_data.host_keys[i];
723 if (key != NULL && key->type == type)
730 get_hostkey_by_index(int ind)
732 if (ind < 0 || ind >= options.num_host_key_files)
734 return (sensitive_data.host_keys[ind]);
738 get_hostkey_index(Key *key)
742 for (i = 0; i < options.num_host_key_files; i++) {
743 if (key == sensitive_data.host_keys[i])
750 * returns 1 if connection should be dropped, 0 otherwise.
751 * dropping starts at connection #max_startups_begin with a probability
752 * of (max_startups_rate/100). the probability increases linearly until
753 * all connections are dropped for startups > max_startups
756 drop_connection(int startups)
760 if (startups < options.max_startups_begin)
762 if (startups >= options.max_startups)
764 if (options.max_startups_rate == 100)
767 p = 100 - options.max_startups_rate;
768 p *= startups - options.max_startups_begin;
769 p /= options.max_startups - options.max_startups_begin;
770 p += options.max_startups_rate;
771 r = arc4random() % 100;
773 debug("drop_connection: p %d, r %d", p, r);
774 return (r < p) ? 1 : 0;
780 fprintf(stderr, "%s, %s\n",
781 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
783 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
784 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
790 send_rexec_state(int fd, Buffer *conf)
794 debug3("%s: entering fd = %d config len %d", __func__, fd,
798 * Protocol from reexec master to child:
799 * string configuration
800 * u_int ephemeral_key_follows
801 * bignum e (only if ephemeral_key_follows == 1)
807 * string rngseed (only if OpenSSL is not self-seeded)
810 buffer_put_cstring(&m, buffer_ptr(conf));
812 if (sensitive_data.server_key != NULL &&
813 sensitive_data.server_key->type == KEY_RSA1) {
814 buffer_put_int(&m, 1);
815 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
816 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
817 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
818 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
819 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
820 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
822 buffer_put_int(&m, 0);
824 #ifndef OPENSSL_PRNG_ONLY
825 rexec_send_rng_seed(&m);
828 if (ssh_msg_send(fd, 0, &m) == -1)
829 fatal("%s: ssh_msg_send failed", __func__);
833 debug3("%s: done", __func__);
837 recv_rexec_state(int fd, Buffer *conf)
843 debug3("%s: entering fd = %d", __func__, fd);
847 if (ssh_msg_recv(fd, &m) == -1)
848 fatal("%s: ssh_msg_recv failed", __func__);
849 if (buffer_get_char(&m) != 0)
850 fatal("%s: rexec version mismatch", __func__);
852 cp = buffer_get_string(&m, &len);
854 buffer_append(conf, cp, len + 1);
857 if (buffer_get_int(&m)) {
858 if (sensitive_data.server_key != NULL)
859 key_free(sensitive_data.server_key);
860 sensitive_data.server_key = key_new_private(KEY_RSA1);
861 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
862 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
863 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
864 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
865 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
866 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
867 rsa_generate_additional_parameters(
868 sensitive_data.server_key->rsa);
871 #ifndef OPENSSL_PRNG_ONLY
872 rexec_recv_rng_seed(&m);
877 debug3("%s: done", __func__);
881 * Main program for the daemon.
884 main(int ac, char **av)
888 int opt, j, i, fdsetsz, on = 1;
889 int sock_in = -1, sock_out = -1, newsock = -1;
893 struct sockaddr_storage from;
894 const char *remote_ip;
898 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
900 int listen_sock, maxfd;
901 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
905 int ret, key_used = 0;
908 #ifdef HAVE_SECUREWARE
909 (void)set_auth_parameters(ac, av);
911 __progname = ssh_get_progname(av[0]);
914 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
917 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
918 for (i = 0; i < ac; i++)
919 saved_argv[i] = xstrdup(av[i]);
920 saved_argv[i] = NULL;
922 #ifndef HAVE_SETPROCTITLE
923 /* Prepare for later setproctitle emulation */
924 compat_init_setproctitle(ac, av);
928 if (geteuid() == 0 && setgroups(0, NULL) == -1)
929 debug("setgroups(): %.200s", strerror(errno));
931 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
934 /* Initialize configuration options to their default values. */
935 initialize_server_options(&options);
937 /* Parse command-line arguments. */
938 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
941 options.address_family = AF_INET;
944 options.address_family = AF_INET6;
947 config_file_name = optarg;
950 if (debug_flag == 0) {
952 options.log_level = SYSLOG_LEVEL_DEBUG1;
953 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
976 options.log_level = SYSLOG_LEVEL_QUIET;
979 options.server_key_bits = atoi(optarg);
982 options.ports_from_cmdline = 1;
983 if (options.num_ports >= MAX_PORTS) {
984 fprintf(stderr, "too many ports.\n");
987 options.ports[options.num_ports++] = a2port(optarg);
988 if (options.ports[options.num_ports-1] == 0) {
989 fprintf(stderr, "Bad port number.\n");
994 if ((options.login_grace_time = convtime(optarg)) == -1) {
995 fprintf(stderr, "Invalid login grace time.\n");
1000 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1001 fprintf(stderr, "Invalid key regeneration interval.\n");
1006 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1007 fprintf(stderr, "too many host keys.\n");
1010 options.host_key_files[options.num_host_key_files++] = optarg;
1016 utmp_len = atoi(optarg);
1017 if (utmp_len > MAXHOSTNAMELEN) {
1018 fprintf(stderr, "Invalid utmp length.\n");
1023 line = xstrdup(optarg);
1024 if (process_server_config_line(&options, line,
1025 "command-line", 0) != 0)
1035 if (rexeced_flag || inetd_flag)
1037 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1038 fatal("sshd re-exec requires execution with an absolute path");
1040 closefrom(REEXEC_MIN_FREE_FD);
1042 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1044 SSLeay_add_all_algorithms();
1047 * Force logging to stderr until we have loaded the private host
1048 * key (unless started from inetd)
1050 log_init(__progname,
1051 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1052 SYSLOG_LEVEL_INFO : options.log_level,
1053 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1054 SYSLOG_FACILITY_AUTH : options.log_facility,
1055 log_stderr || !inetd_flag);
1058 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1059 * root's environment
1061 if (getenv("KRB5CCNAME") != NULL)
1062 unsetenv("KRB5CCNAME");
1065 /* Cray can define user privs drop all privs now!
1066 * Not needed on PRIV_SU systems!
1071 sensitive_data.server_key = NULL;
1072 sensitive_data.ssh1_host_key = NULL;
1073 sensitive_data.have_ssh1_key = 0;
1074 sensitive_data.have_ssh2_key = 0;
1076 /* Fetch our configuration */
1079 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1081 load_server_config(config_file_name, &cfg);
1083 parse_server_config(&options,
1084 rexeced_flag ? "rexec" : config_file_name, &cfg);
1091 /* Fill in default values for those options not explicitly set. */
1092 fill_default_server_options(&options);
1094 /* set default channel AF */
1095 channel_set_af(options.address_family);
1097 /* Check that there are no remaining arguments. */
1099 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1103 debug("sshd version %.100s", SSH_RELEASE);
1105 /* load private host keys */
1106 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1108 for (i = 0; i < options.num_host_key_files; i++)
1109 sensitive_data.host_keys[i] = NULL;
1111 for (i = 0; i < options.num_host_key_files; i++) {
1112 key = key_load_private(options.host_key_files[i], "", NULL);
1113 sensitive_data.host_keys[i] = key;
1115 error("Could not load host key: %s",
1116 options.host_key_files[i]);
1117 sensitive_data.host_keys[i] = NULL;
1120 switch (key->type) {
1122 sensitive_data.ssh1_host_key = key;
1123 sensitive_data.have_ssh1_key = 1;
1127 sensitive_data.have_ssh2_key = 1;
1130 debug("private host key: #%d type %d %s", i, key->type,
1133 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1134 logit("Disabling protocol version 1. Could not load host key");
1135 options.protocol &= ~SSH_PROTO_1;
1137 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1138 logit("Disabling protocol version 2. Could not load host key");
1139 options.protocol &= ~SSH_PROTO_2;
1141 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1142 logit("sshd: no hostkeys available -- exiting.");
1146 /* Check certain values for sanity. */
1147 if (options.protocol & SSH_PROTO_1) {
1148 if (options.server_key_bits < 512 ||
1149 options.server_key_bits > 32768) {
1150 fprintf(stderr, "Bad server key size.\n");
1154 * Check that server and host key lengths differ sufficiently. This
1155 * is necessary to make double encryption work with rsaref. Oh, I
1156 * hate software patents. I dont know if this can go? Niels
1158 if (options.server_key_bits >
1159 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1160 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1161 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1162 SSH_KEY_BITS_RESERVED) {
1163 options.server_key_bits =
1164 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1165 SSH_KEY_BITS_RESERVED;
1166 debug("Forcing server key to %d bits to make it differ from host key.",
1167 options.server_key_bits);
1175 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1176 fatal("Privilege separation user %s does not exist",
1178 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1179 (S_ISDIR(st.st_mode) == 0))
1180 fatal("Missing privilege separation directory: %s",
1181 _PATH_PRIVSEP_CHROOT_DIR);
1184 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1185 (st.st_uid != getuid () ||
1186 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1188 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1190 fatal("%s must be owned by root and not group or "
1191 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1194 /* Configuration looks good, so exit if in test mode. */
1199 * Clear out any supplemental groups we may have inherited. This
1200 * prevents inadvertent creation of files with bad modes (in the
1201 * portable version at least, it's certainly possible for PAM
1202 * to create a file, and we can't control the code in every
1203 * module which might be used).
1205 if (setgroups(0, NULL) < 0)
1206 debug("setgroups() failed: %.200s", strerror(errno));
1209 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1210 for (i = 0; i < rexec_argc; i++) {
1211 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1212 rexec_argv[i] = saved_argv[i];
1214 rexec_argv[rexec_argc] = "-R";
1215 rexec_argv[rexec_argc + 1] = NULL;
1218 /* Initialize the log (it is reinitialized below in case we forked). */
1219 if (debug_flag && (!inetd_flag || rexeced_flag))
1221 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1224 * If not in debugging mode, and not started from inetd, disconnect
1225 * from the controlling terminal, and fork. The original process
1228 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1231 #endif /* TIOCNOTTY */
1232 if (daemon(0, 0) < 0)
1233 fatal("daemon() failed: %.200s", strerror(errno));
1235 /* Disconnect from the controlling tty. */
1237 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1239 (void) ioctl(fd, TIOCNOTTY, NULL);
1242 #endif /* TIOCNOTTY */
1244 /* Reinitialize the log (because of the fork above). */
1245 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1247 /* Initialize the random number generator. */
1250 /* Chdir to the root directory so that the current disk can be
1251 unmounted if desired. */
1254 /* ignore SIGPIPE */
1255 signal(SIGPIPE, SIG_IGN);
1257 /* Start listening for a socket, unless started from inetd. */
1263 close(REEXEC_CONFIG_PASS_FD);
1264 sock_in = sock_out = dup(STDIN_FILENO);
1266 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1267 close(REEXEC_STARTUP_PIPE_FD);
1270 sock_in = dup(STDIN_FILENO);
1271 sock_out = dup(STDOUT_FILENO);
1274 * We intentionally do not close the descriptors 0, 1, and 2
1275 * as our code for setting the descriptors won't work if
1276 * ttyfd happens to be one of those.
1278 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1279 dup2(fd, STDIN_FILENO);
1280 dup2(fd, STDOUT_FILENO);
1281 if (fd > STDOUT_FILENO)
1284 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1285 if ((options.protocol & SSH_PROTO_1) &&
1286 sensitive_data.server_key == NULL)
1287 generate_ephemeral_server_key();
1289 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1290 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1292 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1293 fatal("Too many listen sockets. "
1294 "Enlarge MAX_LISTEN_SOCKS");
1295 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1296 ntop, sizeof(ntop), strport, sizeof(strport),
1297 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1298 error("getnameinfo failed: %.100s",
1299 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1303 /* Create socket for listening. */
1304 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1306 if (listen_sock < 0) {
1307 /* kernel may not support ipv6 */
1308 verbose("socket: %.100s", strerror(errno));
1311 if (set_nonblock(listen_sock) == -1) {
1316 * Set socket options.
1317 * Allow local port reuse in TIME_WAIT.
1319 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1320 &on, sizeof(on)) == -1)
1321 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1323 debug("Bind to port %s on %s.", strport, ntop);
1325 /* Bind the socket to the desired port. */
1326 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1328 error("Bind to port %s on %s failed: %.200s.",
1329 strport, ntop, strerror(errno));
1333 listen_socks[num_listen_socks] = listen_sock;
1336 /* Start listening on the port. */
1337 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1338 fatal("listen on [%s]:%s: %.100s",
1339 ntop, strport, strerror(errno));
1340 logit("Server listening on %s port %s.", ntop, strport);
1342 freeaddrinfo(options.listen_addrs);
1344 if (!num_listen_socks)
1345 fatal("Cannot bind any address.");
1347 if (options.protocol & SSH_PROTO_1)
1348 generate_ephemeral_server_key();
1351 * Arrange to restart on SIGHUP. The handler needs
1354 signal(SIGHUP, sighup_handler);
1356 signal(SIGTERM, sigterm_handler);
1357 signal(SIGQUIT, sigterm_handler);
1359 /* Arrange SIGCHLD to be caught. */
1360 signal(SIGCHLD, main_sigchld_handler);
1362 /* Write out the pid file after the sigterm handler is setup */
1365 * Record our pid in /var/run/sshd.pid to make it
1366 * easier to kill the correct sshd. We don't want to
1367 * do this before the bind above because the bind will
1368 * fail if there already is a daemon, and this will
1369 * overwrite any old pid in the file.
1371 f = fopen(options.pid_file, "wb");
1373 error("Couldn't create pid file \"%s\": %s",
1374 options.pid_file, strerror(errno));
1376 fprintf(f, "%ld\n", (long) getpid());
1381 /* setup fd set for listen */
1384 for (i = 0; i < num_listen_socks; i++)
1385 if (listen_socks[i] > maxfd)
1386 maxfd = listen_socks[i];
1387 /* pipes connected to unauthenticated childs */
1388 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1389 for (i = 0; i < options.max_startups; i++)
1390 startup_pipes[i] = -1;
1393 * Stay listening for connections until the system crashes or
1394 * the daemon is killed with a signal.
1397 if (received_sighup)
1401 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1402 fdset = (fd_set *)xmalloc(fdsetsz);
1403 memset(fdset, 0, fdsetsz);
1405 for (i = 0; i < num_listen_socks; i++)
1406 FD_SET(listen_socks[i], fdset);
1407 for (i = 0; i < options.max_startups; i++)
1408 if (startup_pipes[i] != -1)
1409 FD_SET(startup_pipes[i], fdset);
1411 /* Wait in select until there is a connection. */
1412 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1413 if (ret < 0 && errno != EINTR)
1414 error("select: %.100s", strerror(errno));
1415 if (received_sigterm) {
1416 logit("Received signal %d; terminating.",
1417 (int) received_sigterm);
1418 close_listen_socks();
1419 unlink(options.pid_file);
1422 if (key_used && key_do_regen) {
1423 generate_ephemeral_server_key();
1430 for (i = 0; i < options.max_startups; i++)
1431 if (startup_pipes[i] != -1 &&
1432 FD_ISSET(startup_pipes[i], fdset)) {
1434 * the read end of the pipe is ready
1435 * if the child has closed the pipe
1436 * after successful authentication
1437 * or if the child has died
1439 close(startup_pipes[i]);
1440 startup_pipes[i] = -1;
1443 for (i = 0; i < num_listen_socks; i++) {
1444 if (!FD_ISSET(listen_socks[i], fdset))
1446 fromlen = sizeof(from);
1447 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1450 if (errno != EINTR && errno != EWOULDBLOCK)
1451 error("accept: %.100s", strerror(errno));
1454 if (unset_nonblock(newsock) == -1) {
1458 if (drop_connection(startups) == 1) {
1459 debug("drop connection #%d", startups);
1463 if (pipe(startup_p) == -1) {
1468 if (rexec_flag && socketpair(AF_UNIX,
1469 SOCK_STREAM, 0, config_s) == -1) {
1470 error("reexec socketpair: %s",
1473 close(startup_p[0]);
1474 close(startup_p[1]);
1478 for (j = 0; j < options.max_startups; j++)
1479 if (startup_pipes[j] == -1) {
1480 startup_pipes[j] = startup_p[0];
1481 if (maxfd < startup_p[0])
1482 maxfd = startup_p[0];
1488 * Got connection. Fork a child to handle it, unless
1489 * we are in debugging mode.
1493 * In debugging mode. Close the listening
1494 * socket, and start processing the
1495 * connection without forking.
1497 debug("Server will not fork when running in debugging mode.");
1498 close_listen_socks();
1501 close(startup_p[0]);
1502 close(startup_p[1]);
1506 send_rexec_state(config_s[0],
1513 * Normal production daemon. Fork, and have
1514 * the child process the connection. The
1515 * parent continues listening.
1517 if ((pid = fork()) == 0) {
1519 * Child. Close the listening and max_startup
1520 * sockets. Start using the accepted socket.
1521 * Reinitialize logging (since our pid has
1522 * changed). We break out of the loop to handle
1525 startup_pipe = startup_p[1];
1526 close_startup_pipes();
1527 close_listen_socks();
1530 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1537 /* Parent. Stay in the loop. */
1539 error("fork: %.100s", strerror(errno));
1541 debug("Forked child %ld.", (long)pid);
1543 close(startup_p[1]);
1546 send_rexec_state(config_s[0], &cfg);
1551 /* Mark that the key has been used (it was "given" to the child). */
1552 if ((options.protocol & SSH_PROTO_1) &&
1554 /* Schedule server key regeneration alarm. */
1555 signal(SIGALRM, key_regeneration_alarm);
1556 alarm(options.key_regeneration_time);
1562 /* Close the new socket (the child is now taking care of it). */
1565 /* child process check (or debug mode) */
1566 if (num_listen_socks < 0)
1571 /* This is the child processing a new connection. */
1572 setproctitle("%s", "[accepted]");
1575 * Create a new session and process group since the 4.4BSD
1576 * setlogin() affects the entire process group. We don't
1577 * want the child to be able to affect the parent.
1579 #if !defined(SSHD_ACQUIRES_CTTY)
1581 * If setsid is called, on some platforms sshd will later acquire a
1582 * controlling terminal which will result in "could not set
1583 * controlling tty" errors.
1585 if (!debug_flag && !inetd_flag && setsid() < 0)
1586 error("setsid: %.100s", strerror(errno));
1592 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1593 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1594 dup2(newsock, STDIN_FILENO);
1595 dup2(STDIN_FILENO, STDOUT_FILENO);
1596 if (startup_pipe == -1)
1597 close(REEXEC_STARTUP_PIPE_FD);
1599 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1601 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1603 if (startup_pipe != -1)
1604 close(startup_pipe);
1606 execv(rexec_argv[0], rexec_argv);
1608 /* Reexec has failed, fall back and continue */
1609 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1610 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1611 log_init(__progname, options.log_level,
1612 options.log_facility, log_stderr);
1615 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1617 close(REEXEC_CONFIG_PASS_FD);
1618 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1619 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1620 dup2(fd, STDIN_FILENO);
1621 dup2(fd, STDOUT_FILENO);
1622 if (fd > STDERR_FILENO)
1625 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1626 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1630 * Disable the key regeneration alarm. We will not regenerate the
1631 * key since we are no longer in a position to give it to anyone. We
1632 * will not restart on SIGHUP since it no longer makes sense.
1635 signal(SIGALRM, SIG_DFL);
1636 signal(SIGHUP, SIG_DFL);
1637 signal(SIGTERM, SIG_DFL);
1638 signal(SIGQUIT, SIG_DFL);
1639 signal(SIGCHLD, SIG_DFL);
1640 signal(SIGINT, SIG_DFL);
1643 * Register our connection. This turns encryption off because we do
1646 packet_set_connection(sock_in, sock_out);
1647 packet_set_server();
1649 /* Set SO_KEEPALIVE if requested. */
1650 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1651 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1652 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1654 if ((remote_port = get_remote_port()) < 0) {
1655 debug("get_remote_port failed");
1660 * We use get_canonical_hostname with usedns = 0 instead of
1661 * get_remote_ipaddr here so IP options will be checked.
1663 remote_ip = get_canonical_hostname(0);
1665 #ifdef SSH_AUDIT_EVENTS
1666 audit_connection_from(remote_ip, remote_port);
1669 /* Check whether logins are denied from this host. */
1670 if (packet_connection_is_on_socket()) {
1671 struct request_info req;
1673 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1676 if (!hosts_access(&req)) {
1677 debug("Connection refused by tcp wrapper");
1680 fatal("libwrap refuse returns");
1683 #endif /* LIBWRAP */
1685 /* Log the connection. */
1686 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1689 * We don't want to listen forever unless the other side
1690 * successfully authenticates itself. So we set up an alarm which is
1691 * cleared after successful authentication. A limit of zero
1692 * indicates no limit. Note that we don't set the alarm in debugging
1693 * mode; it is just annoying to have the server exit just when you
1694 * are about to discover the bug.
1696 signal(SIGALRM, grace_alarm_handler);
1698 alarm(options.login_grace_time);
1700 sshd_exchange_identification(sock_in, sock_out);
1702 packet_set_nonblocking();
1704 /* allocate authentication context */
1705 authctxt = xmalloc(sizeof(*authctxt));
1706 memset(authctxt, 0, sizeof(*authctxt));
1708 authctxt->loginmsg = &loginmsg;
1710 /* XXX global for cleanup, access from other modules */
1711 the_authctxt = authctxt;
1713 /* prepare buffer to collect messages to display to user after login */
1714 buffer_init(&loginmsg);
1717 if (privsep_preauth(authctxt) == 1)
1720 /* perform the key exchange */
1721 /* authenticate user and start session */
1724 do_authentication2(authctxt);
1727 do_authentication(authctxt);
1730 * If we use privilege separation, the unprivileged child transfers
1731 * the current keystate and exits
1734 mm_send_keystate(pmonitor);
1740 * Cancel the alarm we set to limit the time taken for
1744 signal(SIGALRM, SIG_DFL);
1745 if (startup_pipe != -1) {
1746 close(startup_pipe);
1750 #ifdef SSH_AUDIT_EVENTS
1751 audit_event(SSH_AUTH_SUCCESS);
1755 * In privilege separation, we fork another child and prepare
1756 * file descriptor passing.
1759 privsep_postauth(authctxt);
1760 /* the monitor process [priv] will not return */
1762 destroy_sensitive_data();
1765 /* Start session. */
1766 do_authenticated(authctxt);
1768 /* The connection has been terminated. */
1769 verbose("Closing connection to %.100s", remote_ip);
1772 if (options.use_pam)
1774 #endif /* USE_PAM */
1776 #ifdef SSH_AUDIT_EVENTS
1777 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1789 * Decrypt session_key_int using our private server key and private host key
1790 * (key with larger modulus first).
1793 ssh1_session_key(BIGNUM *session_key_int)
1797 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1798 /* Server key has bigger modulus. */
1799 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1800 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1801 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1802 get_remote_ipaddr(),
1803 BN_num_bits(sensitive_data.server_key->rsa->n),
1804 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1805 SSH_KEY_BITS_RESERVED);
1807 if (rsa_private_decrypt(session_key_int, session_key_int,
1808 sensitive_data.server_key->rsa) <= 0)
1810 if (rsa_private_decrypt(session_key_int, session_key_int,
1811 sensitive_data.ssh1_host_key->rsa) <= 0)
1814 /* Host key has bigger modulus (or they are equal). */
1815 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1816 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1817 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1818 get_remote_ipaddr(),
1819 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1820 BN_num_bits(sensitive_data.server_key->rsa->n),
1821 SSH_KEY_BITS_RESERVED);
1823 if (rsa_private_decrypt(session_key_int, session_key_int,
1824 sensitive_data.ssh1_host_key->rsa) < 0)
1826 if (rsa_private_decrypt(session_key_int, session_key_int,
1827 sensitive_data.server_key->rsa) < 0)
1840 BIGNUM *session_key_int;
1841 u_char session_key[SSH_SESSION_KEY_LENGTH];
1843 u_int cipher_type, auth_mask, protocol_flags;
1847 * Generate check bytes that the client must send back in the user
1848 * packet in order for it to be accepted; this is used to defy ip
1849 * spoofing attacks. Note that this only works against somebody
1850 * doing IP spoofing from a remote machine; any machine on the local
1851 * network can still see outgoing packets and catch the random
1852 * cookie. This only affects rhosts authentication, and this is one
1853 * of the reasons why it is inherently insecure.
1855 for (i = 0; i < 8; i++) {
1858 cookie[i] = rnd & 0xff;
1863 * Send our public key. We include in the packet 64 bits of random
1864 * data that must be matched in the reply in order to prevent IP
1867 packet_start(SSH_SMSG_PUBLIC_KEY);
1868 for (i = 0; i < 8; i++)
1869 packet_put_char(cookie[i]);
1871 /* Store our public server RSA key. */
1872 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1873 packet_put_bignum(sensitive_data.server_key->rsa->e);
1874 packet_put_bignum(sensitive_data.server_key->rsa->n);
1876 /* Store our public host RSA key. */
1877 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1878 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1879 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1881 /* Put protocol flags. */
1882 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1884 /* Declare which ciphers we support. */
1885 packet_put_int(cipher_mask_ssh1(0));
1887 /* Declare supported authentication types. */
1889 if (options.rhosts_rsa_authentication)
1890 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1891 if (options.rsa_authentication)
1892 auth_mask |= 1 << SSH_AUTH_RSA;
1893 if (options.challenge_response_authentication == 1)
1894 auth_mask |= 1 << SSH_AUTH_TIS;
1895 if (options.password_authentication)
1896 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1897 packet_put_int(auth_mask);
1899 /* Send the packet and wait for it to be sent. */
1901 packet_write_wait();
1903 debug("Sent %d bit server key and %d bit host key.",
1904 BN_num_bits(sensitive_data.server_key->rsa->n),
1905 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1907 /* Read clients reply (cipher type and session key). */
1908 packet_read_expect(SSH_CMSG_SESSION_KEY);
1910 /* Get cipher type and check whether we accept this. */
1911 cipher_type = packet_get_char();
1913 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1914 packet_disconnect("Warning: client selects unsupported cipher.");
1916 /* Get check bytes from the packet. These must match those we
1917 sent earlier with the public key packet. */
1918 for (i = 0; i < 8; i++)
1919 if (cookie[i] != packet_get_char())
1920 packet_disconnect("IP Spoofing check bytes do not match.");
1922 debug("Encryption type: %.200s", cipher_name(cipher_type));
1924 /* Get the encrypted integer. */
1925 if ((session_key_int = BN_new()) == NULL)
1926 fatal("do_ssh1_kex: BN_new failed");
1927 packet_get_bignum(session_key_int);
1929 protocol_flags = packet_get_int();
1930 packet_set_protocol_flags(protocol_flags);
1933 /* Decrypt session_key_int using host/server keys */
1934 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1937 * Extract session key from the decrypted integer. The key is in the
1938 * least significant 256 bits of the integer; the first byte of the
1939 * key is in the highest bits.
1942 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1943 len = BN_num_bytes(session_key_int);
1944 if (len < 0 || (u_int)len > sizeof(session_key)) {
1945 error("do_connection: bad session key len from %s: "
1946 "session_key_int %d > sizeof(session_key) %lu",
1947 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1950 memset(session_key, 0, sizeof(session_key));
1951 BN_bn2bin(session_key_int,
1952 session_key + sizeof(session_key) - len);
1954 derive_ssh1_session_id(
1955 sensitive_data.ssh1_host_key->rsa->n,
1956 sensitive_data.server_key->rsa->n,
1957 cookie, session_id);
1959 * Xor the first 16 bytes of the session key with the
1962 for (i = 0; i < 16; i++)
1963 session_key[i] ^= session_id[i];
1967 int bytes = BN_num_bytes(session_key_int);
1968 u_char *buf = xmalloc(bytes);
1971 logit("do_connection: generating a fake encryption key");
1972 BN_bn2bin(session_key_int, buf);
1974 MD5_Update(&md, buf, bytes);
1975 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1976 MD5_Final(session_key, &md);
1978 MD5_Update(&md, session_key, 16);
1979 MD5_Update(&md, buf, bytes);
1980 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1981 MD5_Final(session_key + 16, &md);
1982 memset(buf, 0, bytes);
1984 for (i = 0; i < 16; i++)
1985 session_id[i] = session_key[i] ^ session_key[i + 16];
1987 /* Destroy the private and public keys. No longer. */
1988 destroy_sensitive_data();
1991 mm_ssh1_session_id(session_id);
1993 /* Destroy the decrypted integer. It is no longer needed. */
1994 BN_clear_free(session_key_int);
1996 /* Set the session key. From this on all communications will be encrypted. */
1997 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1999 /* Destroy our copy of the session key. It is no longer needed. */
2000 memset(session_key, 0, sizeof(session_key));
2002 debug("Received session key; encryption turned on.");
2004 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2005 packet_start(SSH_SMSG_SUCCESS);
2007 packet_write_wait();
2011 * SSH2 key exchange: diffie-hellman-group1-sha1
2018 if (options.ciphers != NULL) {
2019 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2020 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2022 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2023 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2024 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2025 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2027 if (options.macs != NULL) {
2028 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2029 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2031 if (options.compression == COMP_NONE) {
2032 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2033 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2034 } else if (options.compression == COMP_DELAYED) {
2035 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2036 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2039 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2041 /* start key exchange */
2042 kex = kex_setup(myproposal);
2043 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2044 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2045 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2046 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2048 kex->client_version_string=client_version_string;
2049 kex->server_version_string=server_version_string;
2050 kex->load_host_key=&get_hostkey_by_type;
2051 kex->host_key_index=&get_hostkey_index;
2055 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2057 session_id2 = kex->session_id;
2058 session_id2_len = kex->session_id_len;
2061 /* send 1st encrypted/maced/compressed message */
2062 packet_start(SSH2_MSG_IGNORE);
2063 packet_put_cstring("markus");
2065 packet_write_wait();
2070 /* server specific fatal cleanup */
2075 do_cleanup(the_authctxt);
2076 #ifdef SSH_AUDIT_EVENTS
2077 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2078 if (!use_privsep || mm_is_monitor())
2079 audit_event(SSH_CONNECTION_ABANDON);