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 1.301 2004/08/11 11:50:09 dtucker 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>
78 #include "myproposal.h"
80 #include "pathnames.h"
89 #include "monitor_mm.h"
91 #include "monitor_wrap.h"
92 #include "monitor_fdpass.h"
97 int allow_severity = LOG_INFO;
98 int deny_severity = LOG_WARNING;
106 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
107 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
108 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
109 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
111 extern char *__progname;
113 /* Server configuration options. */
114 ServerOptions options;
116 /* Name of the server configuration file. */
117 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
120 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
121 * Default value is AF_UNSPEC means both IPv4 and IPv6.
123 int IPv4or6 = AF_UNSPEC;
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)
373 int remote_major, remote_minor;
376 char buf[256]; /* Must not be larger than remote_version. */
377 char remote_version[256]; /* Must be at least as big as buf. */
379 if ((options.protocol & SSH_PROTO_1) &&
380 (options.protocol & SSH_PROTO_2)) {
381 major = PROTOCOL_MAJOR_1;
383 } else if (options.protocol & SSH_PROTO_2) {
384 major = PROTOCOL_MAJOR_2;
385 minor = PROTOCOL_MINOR_2;
387 major = PROTOCOL_MAJOR_1;
388 minor = PROTOCOL_MINOR_1;
390 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
391 server_version_string = xstrdup(buf);
393 /* Send our protocol version identification. */
394 if (atomicio(vwrite, sock_out, server_version_string,
395 strlen(server_version_string))
396 != strlen(server_version_string)) {
397 logit("Could not write ident string to %s", get_remote_ipaddr());
401 /* Read other sides version identification. */
402 memset(buf, 0, sizeof(buf));
403 for (i = 0; i < sizeof(buf) - 1; i++) {
404 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
405 logit("Did not receive identification string from %s",
406 get_remote_ipaddr());
409 if (buf[i] == '\r') {
411 /* Kludge for F-Secure Macintosh < 1.0.2 */
413 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
417 if (buf[i] == '\n') {
422 buf[sizeof(buf) - 1] = 0;
423 client_version_string = xstrdup(buf);
426 * Check that the versions match. In future this might accept
427 * several versions and set appropriate flags to handle them.
429 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
430 &remote_major, &remote_minor, remote_version) != 3) {
431 s = "Protocol mismatch.\n";
432 (void) atomicio(vwrite, sock_out, s, strlen(s));
435 logit("Bad protocol version identification '%.100s' from %s",
436 client_version_string, get_remote_ipaddr());
439 debug("Client protocol version %d.%d; client software version %.100s",
440 remote_major, remote_minor, remote_version);
442 compat_datafellows(remote_version);
444 if (datafellows & SSH_BUG_PROBE) {
445 logit("probed from %s with %s. Don't panic.",
446 get_remote_ipaddr(), client_version_string);
450 if (datafellows & SSH_BUG_SCANNER) {
451 logit("scanned from %s with %s. Don't panic.",
452 get_remote_ipaddr(), client_version_string);
457 switch (remote_major) {
459 if (remote_minor == 99) {
460 if (options.protocol & SSH_PROTO_2)
466 if (!(options.protocol & SSH_PROTO_1)) {
470 if (remote_minor < 3) {
471 packet_disconnect("Your ssh version is too old and "
472 "is no longer supported. Please install a newer version.");
473 } else if (remote_minor == 3) {
474 /* note that this disables agent-forwarding */
479 if (options.protocol & SSH_PROTO_2) {
488 chop(server_version_string);
489 debug("Local version string %.200s", server_version_string);
492 s = "Protocol major versions differ.\n";
493 (void) atomicio(vwrite, sock_out, s, strlen(s));
496 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
498 server_version_string, client_version_string);
503 /* Destroy the host and server keys. They will no longer be needed. */
505 destroy_sensitive_data(void)
509 if (sensitive_data.server_key) {
510 key_free(sensitive_data.server_key);
511 sensitive_data.server_key = NULL;
513 for (i = 0; i < options.num_host_key_files; i++) {
514 if (sensitive_data.host_keys[i]) {
515 key_free(sensitive_data.host_keys[i]);
516 sensitive_data.host_keys[i] = NULL;
519 sensitive_data.ssh1_host_key = NULL;
520 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
523 /* Demote private to public keys for network child */
525 demote_sensitive_data(void)
530 if (sensitive_data.server_key) {
531 tmp = key_demote(sensitive_data.server_key);
532 key_free(sensitive_data.server_key);
533 sensitive_data.server_key = tmp;
536 for (i = 0; i < options.num_host_key_files; i++) {
537 if (sensitive_data.host_keys[i]) {
538 tmp = key_demote(sensitive_data.host_keys[i]);
539 key_free(sensitive_data.host_keys[i]);
540 sensitive_data.host_keys[i] = tmp;
541 if (tmp->type == KEY_RSA1)
542 sensitive_data.ssh1_host_key = tmp;
546 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
550 privsep_preauth_child(void)
557 /* Enable challenge-response authentication for privilege separation */
558 privsep_challenge_enable();
560 for (i = 0; i < 256; i++)
561 rnd[i] = arc4random();
562 RAND_seed(rnd, sizeof(rnd));
564 /* Demote the private keys to public keys. */
565 demote_sensitive_data();
567 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
568 fatal("Privilege separation user %s does not exist",
570 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
573 /* Change our root directory */
574 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
575 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
577 if (chdir("/") == -1)
578 fatal("chdir(\"/\"): %s", strerror(errno));
580 /* Drop our privileges */
581 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
584 /* XXX not ready, too heavy after chroot */
585 do_setusercontext(pw);
587 gidset[0] = pw->pw_gid;
588 if (setgroups(1, gidset) < 0)
589 fatal("setgroups: %.100s", strerror(errno));
590 permanently_set_uid(pw);
595 privsep_preauth(Authctxt *authctxt)
600 /* Set up unprivileged child process to deal with network data */
601 pmonitor = monitor_init();
602 /* Store a pointer to the kex for later rekeying */
603 pmonitor->m_pkex = &xxx_kex;
607 fatal("fork of unprivileged child failed");
608 } else if (pid != 0) {
609 debug2("Network child is on pid %ld", (long)pid);
611 close(pmonitor->m_recvfd);
612 pmonitor->m_pid = pid;
613 monitor_child_preauth(authctxt, pmonitor);
614 close(pmonitor->m_sendfd);
617 monitor_sync(pmonitor);
619 /* Wait for the child's exit status */
620 while (waitpid(pid, &status, 0) < 0)
627 close(pmonitor->m_sendfd);
629 /* Demote the child */
630 if (getuid() == 0 || geteuid() == 0)
631 privsep_preauth_child();
632 setproctitle("%s", "[net]");
638 privsep_postauth(Authctxt *authctxt)
640 #ifdef DISABLE_FD_PASSING
643 if (authctxt->pw->pw_uid == 0 || options.use_login) {
645 /* File descriptor passing is broken or root login */
646 monitor_apply_keystate(pmonitor);
651 /* Authentication complete */
653 if (startup_pipe != -1) {
658 /* New socket pair */
659 monitor_reinit(pmonitor);
661 pmonitor->m_pid = fork();
662 if (pmonitor->m_pid == -1)
663 fatal("fork of unprivileged child failed");
664 else if (pmonitor->m_pid != 0) {
665 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
666 close(pmonitor->m_recvfd);
667 buffer_clear(&loginmsg);
668 monitor_child_postauth(pmonitor);
674 close(pmonitor->m_sendfd);
676 /* Demote the private keys to public keys. */
677 demote_sensitive_data();
679 /* Drop privileges */
680 do_setusercontext(authctxt->pw);
682 /* It is safe now to apply the key state */
683 monitor_apply_keystate(pmonitor);
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 /= (double) (options.max_startups - options.max_startups_begin);
770 p += options.max_startups_rate;
772 r = arc4random() / (double) UINT_MAX;
774 debug("drop_connection: p %g, r %g", p, r);
775 return (r < p) ? 1 : 0;
781 fprintf(stderr, "%s, %s\n",
782 SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
784 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
785 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
791 send_rexec_state(int fd, Buffer *conf)
795 debug3("%s: entering fd = %d config len %d", __func__, fd,
799 * Protocol from reexec master to child:
800 * string configuration
801 * u_int ephemeral_key_follows
802 * bignum e (only if ephemeral_key_follows == 1)
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 if (ssh_msg_send(fd, 0, &m) == -1)
825 fatal("%s: ssh_msg_send failed", __func__);
829 debug3("%s: done", __func__);
833 recv_rexec_state(int fd, Buffer *conf)
839 debug3("%s: entering fd = %d", __func__, fd);
843 if (ssh_msg_recv(fd, &m) == -1)
844 fatal("%s: ssh_msg_recv failed", __func__);
845 if (buffer_get_char(&m) != 0)
846 fatal("%s: rexec version mismatch", __func__);
848 cp = buffer_get_string(&m, &len);
850 buffer_append(conf, cp, len + 1);
853 if (buffer_get_int(&m)) {
854 if (sensitive_data.server_key != NULL)
855 key_free(sensitive_data.server_key);
856 sensitive_data.server_key = key_new_private(KEY_RSA1);
857 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
858 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
859 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
860 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
861 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
862 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
863 rsa_generate_additional_parameters(
864 sensitive_data.server_key->rsa);
868 debug3("%s: done", __func__);
872 * Main program for the daemon.
875 main(int ac, char **av)
879 int opt, j, i, fdsetsz, on = 1;
880 int sock_in = -1, sock_out = -1, newsock = -1;
884 struct sockaddr_storage from;
885 const char *remote_ip;
889 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
891 int listen_sock, maxfd;
892 int startup_p[2], config_s[2];
896 int ret, key_used = 0;
899 #ifdef HAVE_SECUREWARE
900 (void)set_auth_parameters(ac, av);
902 __progname = ssh_get_progname(av[0]);
905 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
908 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
909 for (i = 0; i < ac; i++)
910 saved_argv[i] = xstrdup(av[i]);
911 saved_argv[i] = NULL;
913 #ifndef HAVE_SETPROCTITLE
914 /* Prepare for later setproctitle emulation */
915 compat_init_setproctitle(ac, av);
919 if (geteuid() == 0 && setgroups(0, NULL) == -1)
920 debug("setgroups(): %.200s", strerror(errno));
922 /* Initialize configuration options to their default values. */
923 initialize_server_options(&options);
925 /* Parse command-line arguments. */
926 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
935 config_file_name = optarg;
938 if (debug_flag == 0) {
940 options.log_level = SYSLOG_LEVEL_DEBUG1;
941 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
964 options.log_level = SYSLOG_LEVEL_QUIET;
967 options.server_key_bits = atoi(optarg);
970 options.ports_from_cmdline = 1;
971 if (options.num_ports >= MAX_PORTS) {
972 fprintf(stderr, "too many ports.\n");
975 options.ports[options.num_ports++] = a2port(optarg);
976 if (options.ports[options.num_ports-1] == 0) {
977 fprintf(stderr, "Bad port number.\n");
982 if ((options.login_grace_time = convtime(optarg)) == -1) {
983 fprintf(stderr, "Invalid login grace time.\n");
988 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
989 fprintf(stderr, "Invalid key regeneration interval.\n");
994 if (options.num_host_key_files >= MAX_HOSTKEYS) {
995 fprintf(stderr, "too many host keys.\n");
998 options.host_key_files[options.num_host_key_files++] = optarg;
1004 utmp_len = atoi(optarg);
1005 if (utmp_len > MAXHOSTNAMELEN) {
1006 fprintf(stderr, "Invalid utmp length.\n");
1011 line = xstrdup(optarg);
1012 if (process_server_config_line(&options, line,
1013 "command-line", 0) != 0)
1023 if (rexeced_flag || inetd_flag)
1025 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1026 fatal("sshd re-exec requires execution with an absolute path");
1028 closefrom(REEXEC_MIN_FREE_FD);
1030 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1032 SSLeay_add_all_algorithms();
1033 channel_set_af(IPv4or6);
1036 * Force logging to stderr until we have loaded the private host
1037 * key (unless started from inetd)
1039 log_init(__progname,
1040 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1041 SYSLOG_LEVEL_INFO : options.log_level,
1042 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1043 SYSLOG_FACILITY_AUTH : options.log_facility,
1044 log_stderr || !inetd_flag);
1048 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1049 * root's environment
1051 unsetenv("KRB5CCNAME");
1054 /* Cray can define user privs drop all privs now!
1055 * Not needed on PRIV_SU systems!
1062 sensitive_data.server_key = NULL;
1063 sensitive_data.ssh1_host_key = NULL;
1064 sensitive_data.have_ssh1_key = 0;
1065 sensitive_data.have_ssh2_key = 0;
1067 /* Fetch our configuration */
1070 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1072 load_server_config(config_file_name, &cfg);
1074 parse_server_config(&options,
1075 rexeced_flag ? "rexec" : config_file_name, &cfg);
1080 /* Fill in default values for those options not explicitly set. */
1081 fill_default_server_options(&options);
1083 /* Check that there are no remaining arguments. */
1085 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1089 debug("sshd version %.100s", SSH_VERSION);
1091 /* load private host keys */
1092 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1094 for (i = 0; i < options.num_host_key_files; i++)
1095 sensitive_data.host_keys[i] = NULL;
1097 for (i = 0; i < options.num_host_key_files; i++) {
1098 key = key_load_private(options.host_key_files[i], "", NULL);
1099 sensitive_data.host_keys[i] = key;
1101 error("Could not load host key: %s",
1102 options.host_key_files[i]);
1103 sensitive_data.host_keys[i] = NULL;
1106 switch (key->type) {
1108 sensitive_data.ssh1_host_key = key;
1109 sensitive_data.have_ssh1_key = 1;
1113 sensitive_data.have_ssh2_key = 1;
1116 debug("private host key: #%d type %d %s", i, key->type,
1119 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1120 logit("Disabling protocol version 1. Could not load host key");
1121 options.protocol &= ~SSH_PROTO_1;
1123 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1124 logit("Disabling protocol version 2. Could not load host key");
1125 options.protocol &= ~SSH_PROTO_2;
1127 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1128 logit("sshd: no hostkeys available -- exiting.");
1132 /* Check certain values for sanity. */
1133 if (options.protocol & SSH_PROTO_1) {
1134 if (options.server_key_bits < 512 ||
1135 options.server_key_bits > 32768) {
1136 fprintf(stderr, "Bad server key size.\n");
1140 * Check that server and host key lengths differ sufficiently. This
1141 * is necessary to make double encryption work with rsaref. Oh, I
1142 * hate software patents. I dont know if this can go? Niels
1144 if (options.server_key_bits >
1145 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1146 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1147 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1148 SSH_KEY_BITS_RESERVED) {
1149 options.server_key_bits =
1150 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1151 SSH_KEY_BITS_RESERVED;
1152 debug("Forcing server key to %d bits to make it differ from host key.",
1153 options.server_key_bits);
1161 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1162 fatal("Privilege separation user %s does not exist",
1164 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1165 (S_ISDIR(st.st_mode) == 0))
1166 fatal("Missing privilege separation directory: %s",
1167 _PATH_PRIVSEP_CHROOT_DIR);
1170 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1171 (st.st_uid != getuid () ||
1172 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1174 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1176 fatal("%s must be owned by root and not group or "
1177 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1180 /* Configuration looks good, so exit if in test mode. */
1185 * Clear out any supplemental groups we may have inherited. This
1186 * prevents inadvertent creation of files with bad modes (in the
1187 * portable version at least, it's certainly possible for PAM
1188 * to create a file, and we can't control the code in every
1189 * module which might be used).
1191 if (setgroups(0, NULL) < 0)
1192 debug("setgroups() failed: %.200s", strerror(errno));
1195 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1196 for (i = 0; i < rexec_argc; i++) {
1197 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1198 rexec_argv[i] = saved_argv[i];
1200 rexec_argv[rexec_argc] = "-R";
1201 rexec_argv[rexec_argc + 1] = NULL;
1204 /* Initialize the log (it is reinitialized below in case we forked). */
1205 if (debug_flag && !inetd_flag)
1207 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1210 * If not in debugging mode, and not started from inetd, disconnect
1211 * from the controlling terminal, and fork. The original process
1214 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1217 #endif /* TIOCNOTTY */
1218 if (daemon(0, 0) < 0)
1219 fatal("daemon() failed: %.200s", strerror(errno));
1221 /* Disconnect from the controlling tty. */
1223 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1225 (void) ioctl(fd, TIOCNOTTY, NULL);
1228 #endif /* TIOCNOTTY */
1230 /* Reinitialize the log (because of the fork above). */
1231 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1233 /* Initialize the random number generator. */
1236 /* Chdir to the root directory so that the current disk can be
1237 unmounted if desired. */
1240 /* ignore SIGPIPE */
1241 signal(SIGPIPE, SIG_IGN);
1243 /* Start listening for a socket, unless started from inetd. */
1249 close(REEXEC_CONFIG_PASS_FD);
1250 sock_in = sock_out = dup(STDIN_FILENO);
1252 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1253 close(REEXEC_STARTUP_PIPE_FD);
1256 sock_in = dup(STDIN_FILENO);
1257 sock_out = dup(STDOUT_FILENO);
1260 * We intentionally do not close the descriptors 0, 1, and 2
1261 * as our code for setting the descriptors won't work if
1262 * ttyfd happens to be one of those.
1264 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1265 dup2(fd, STDIN_FILENO);
1266 dup2(fd, STDOUT_FILENO);
1267 if (fd > STDOUT_FILENO)
1270 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1271 if ((options.protocol & SSH_PROTO_1) &&
1272 sensitive_data.server_key == NULL)
1273 generate_ephemeral_server_key();
1275 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1276 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1278 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1279 fatal("Too many listen sockets. "
1280 "Enlarge MAX_LISTEN_SOCKS");
1281 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1282 ntop, sizeof(ntop), strport, sizeof(strport),
1283 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1284 error("getnameinfo failed");
1287 /* Create socket for listening. */
1288 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1290 if (listen_sock < 0) {
1291 /* kernel may not support ipv6 */
1292 verbose("socket: %.100s", strerror(errno));
1295 if (set_nonblock(listen_sock) == -1) {
1300 * Set socket options.
1301 * Allow local port reuse in TIME_WAIT.
1303 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1304 &on, sizeof(on)) == -1)
1305 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1307 debug("Bind to port %s on %s.", strport, ntop);
1309 /* Bind the socket to the desired port. */
1310 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1312 error("Bind to port %s on %s failed: %.200s.",
1313 strport, ntop, strerror(errno));
1317 listen_socks[num_listen_socks] = listen_sock;
1320 /* Start listening on the port. */
1321 logit("Server listening on %s port %s.", ntop, strport);
1322 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1323 fatal("listen: %.100s", strerror(errno));
1326 freeaddrinfo(options.listen_addrs);
1328 if (!num_listen_socks)
1329 fatal("Cannot bind any address.");
1331 if (options.protocol & SSH_PROTO_1)
1332 generate_ephemeral_server_key();
1335 * Arrange to restart on SIGHUP. The handler needs
1338 signal(SIGHUP, sighup_handler);
1340 signal(SIGTERM, sigterm_handler);
1341 signal(SIGQUIT, sigterm_handler);
1343 /* Arrange SIGCHLD to be caught. */
1344 signal(SIGCHLD, main_sigchld_handler);
1346 /* Write out the pid file after the sigterm handler is setup */
1349 * Record our pid in /var/run/sshd.pid to make it
1350 * easier to kill the correct sshd. We don't want to
1351 * do this before the bind above because the bind will
1352 * fail if there already is a daemon, and this will
1353 * overwrite any old pid in the file.
1355 f = fopen(options.pid_file, "wb");
1357 error("Couldn't create pid file \"%s\": %s",
1358 options.pid_file, strerror(errno));
1360 fprintf(f, "%ld\n", (long) getpid());
1365 /* setup fd set for listen */
1368 for (i = 0; i < num_listen_socks; i++)
1369 if (listen_socks[i] > maxfd)
1370 maxfd = listen_socks[i];
1371 /* pipes connected to unauthenticated childs */
1372 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1373 for (i = 0; i < options.max_startups; i++)
1374 startup_pipes[i] = -1;
1377 * Stay listening for connections until the system crashes or
1378 * the daemon is killed with a signal.
1381 if (received_sighup)
1385 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1386 fdset = (fd_set *)xmalloc(fdsetsz);
1387 memset(fdset, 0, fdsetsz);
1389 for (i = 0; i < num_listen_socks; i++)
1390 FD_SET(listen_socks[i], fdset);
1391 for (i = 0; i < options.max_startups; i++)
1392 if (startup_pipes[i] != -1)
1393 FD_SET(startup_pipes[i], fdset);
1395 /* Wait in select until there is a connection. */
1396 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1397 if (ret < 0 && errno != EINTR)
1398 error("select: %.100s", strerror(errno));
1399 if (received_sigterm) {
1400 logit("Received signal %d; terminating.",
1401 (int) received_sigterm);
1402 close_listen_socks();
1403 unlink(options.pid_file);
1406 if (key_used && key_do_regen) {
1407 generate_ephemeral_server_key();
1414 for (i = 0; i < options.max_startups; i++)
1415 if (startup_pipes[i] != -1 &&
1416 FD_ISSET(startup_pipes[i], fdset)) {
1418 * the read end of the pipe is ready
1419 * if the child has closed the pipe
1420 * after successful authentication
1421 * or if the child has died
1423 close(startup_pipes[i]);
1424 startup_pipes[i] = -1;
1427 for (i = 0; i < num_listen_socks; i++) {
1428 if (!FD_ISSET(listen_socks[i], fdset))
1430 fromlen = sizeof(from);
1431 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1434 if (errno != EINTR && errno != EWOULDBLOCK)
1435 error("accept: %.100s", strerror(errno));
1438 if (unset_nonblock(newsock) == -1) {
1442 if (drop_connection(startups) == 1) {
1443 debug("drop connection #%d", startups);
1447 if (pipe(startup_p) == -1) {
1452 if (rexec_flag && socketpair(AF_UNIX,
1453 SOCK_STREAM, 0, config_s) == -1) {
1454 error("reexec socketpair: %s",
1457 close(startup_p[0]);
1458 close(startup_p[1]);
1462 for (j = 0; j < options.max_startups; j++)
1463 if (startup_pipes[j] == -1) {
1464 startup_pipes[j] = startup_p[0];
1465 if (maxfd < startup_p[0])
1466 maxfd = startup_p[0];
1472 * Got connection. Fork a child to handle it, unless
1473 * we are in debugging mode.
1477 * In debugging mode. Close the listening
1478 * socket, and start processing the
1479 * connection without forking.
1481 debug("Server will not fork when running in debugging mode.");
1482 close_listen_socks();
1485 close(startup_p[0]);
1486 close(startup_p[1]);
1490 send_rexec_state(config_s[0],
1497 * Normal production daemon. Fork, and have
1498 * the child process the connection. The
1499 * parent continues listening.
1501 if ((pid = fork()) == 0) {
1503 * Child. Close the listening and max_startup
1504 * sockets. Start using the accepted socket.
1505 * Reinitialize logging (since our pid has
1506 * changed). We break out of the loop to handle
1509 startup_pipe = startup_p[1];
1510 close_startup_pipes();
1511 close_listen_socks();
1514 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1520 /* Parent. Stay in the loop. */
1522 error("fork: %.100s", strerror(errno));
1524 debug("Forked child %ld.", (long)pid);
1526 close(startup_p[1]);
1529 send_rexec_state(config_s[0], &cfg);
1534 /* Mark that the key has been used (it was "given" to the child). */
1535 if ((options.protocol & SSH_PROTO_1) &&
1537 /* Schedule server key regeneration alarm. */
1538 signal(SIGALRM, key_regeneration_alarm);
1539 alarm(options.key_regeneration_time);
1545 /* Close the new socket (the child is now taking care of it). */
1548 /* child process check (or debug mode) */
1549 if (num_listen_socks < 0)
1554 /* This is the child processing a new connection. */
1555 setproctitle("%s", "[accepted]");
1558 * Create a new session and process group since the 4.4BSD
1559 * setlogin() affects the entire process group. We don't
1560 * want the child to be able to affect the parent.
1562 #if !defined(SSHD_ACQUIRES_CTTY)
1564 * If setsid is called, on some platforms sshd will later acquire a
1565 * controlling terminal which will result in "could not set
1566 * controlling tty" errors.
1568 if (!debug_flag && !inetd_flag && setsid() < 0)
1569 error("setsid: %.100s", strerror(errno));
1575 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1576 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1577 dup2(newsock, STDIN_FILENO);
1578 dup2(STDIN_FILENO, STDOUT_FILENO);
1579 if (startup_pipe == -1)
1580 close(REEXEC_STARTUP_PIPE_FD);
1582 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1584 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1586 if (startup_pipe != -1)
1587 close(startup_pipe);
1589 execv(rexec_argv[0], rexec_argv);
1591 /* Reexec has failed, fall back and continue */
1592 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1593 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1594 log_init(__progname, options.log_level,
1595 options.log_facility, log_stderr);
1598 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1600 close(REEXEC_CONFIG_PASS_FD);
1601 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1602 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1603 dup2(fd, STDIN_FILENO);
1604 dup2(fd, STDOUT_FILENO);
1605 if (fd > STDERR_FILENO)
1608 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1609 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1613 * Disable the key regeneration alarm. We will not regenerate the
1614 * key since we are no longer in a position to give it to anyone. We
1615 * will not restart on SIGHUP since it no longer makes sense.
1618 signal(SIGALRM, SIG_DFL);
1619 signal(SIGHUP, SIG_DFL);
1620 signal(SIGTERM, SIG_DFL);
1621 signal(SIGQUIT, SIG_DFL);
1622 signal(SIGCHLD, SIG_DFL);
1623 signal(SIGINT, SIG_DFL);
1625 /* Set SO_KEEPALIVE if requested. */
1626 if (options.tcp_keep_alive &&
1627 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1629 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1633 * Initialize the resolver. This may not happen automatically
1634 * before privsep chroot().
1636 if ((_res.options & RES_INIT) == 0) {
1637 debug("res_init()");
1643 * Register our connection. This turns encryption off because we do
1646 packet_set_connection(sock_in, sock_out);
1648 remote_port = get_remote_port();
1649 remote_ip = get_remote_ipaddr();
1652 /* Check whether logins are denied from this host. */
1653 if (packet_connection_is_on_socket()) {
1654 struct request_info req;
1656 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1659 if (!hosts_access(&req)) {
1660 debug("Connection refused by tcp wrapper");
1663 fatal("libwrap refuse returns");
1666 #endif /* LIBWRAP */
1668 /* Log the connection. */
1669 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1672 * We don\'t want to listen forever unless the other side
1673 * successfully authenticates itself. So we set up an alarm which is
1674 * cleared after successful authentication. A limit of zero
1675 * indicates no limit. Note that we don\'t set the alarm in debugging
1676 * mode; it is just annoying to have the server exit just when you
1677 * are about to discover the bug.
1679 signal(SIGALRM, grace_alarm_handler);
1681 alarm(options.login_grace_time);
1683 sshd_exchange_identification(sock_in, sock_out);
1685 packet_set_nonblocking();
1687 /* prepare buffers to collect authentication messages */
1688 buffer_init(&loginmsg);
1690 /* allocate authentication context */
1691 authctxt = xmalloc(sizeof(*authctxt));
1692 memset(authctxt, 0, sizeof(*authctxt));
1694 /* XXX global for cleanup, access from other modules */
1695 the_authctxt = authctxt;
1698 if (privsep_preauth(authctxt) == 1)
1701 /* prepare buffer to collect messages to display to user after login */
1702 buffer_init(&loginmsg);
1704 /* perform the key exchange */
1705 /* authenticate user and start session */
1708 do_authentication2(authctxt);
1711 do_authentication(authctxt);
1714 * If we use privilege separation, the unprivileged child transfers
1715 * the current keystate and exits
1718 mm_send_keystate(pmonitor);
1724 * In privilege separation, we fork another child and prepare
1725 * file descriptor passing.
1728 privsep_postauth(authctxt);
1729 /* the monitor process [priv] will not return */
1731 destroy_sensitive_data();
1734 /* Start session. */
1735 do_authenticated(authctxt);
1737 /* The connection has been terminated. */
1738 verbose("Closing connection to %.100s", remote_ip);
1741 if (options.use_pam)
1743 #endif /* USE_PAM */
1754 * Decrypt session_key_int using our private server key and private host key
1755 * (key with larger modulus first).
1758 ssh1_session_key(BIGNUM *session_key_int)
1762 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1763 /* Server key has bigger modulus. */
1764 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1765 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1766 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1767 get_remote_ipaddr(),
1768 BN_num_bits(sensitive_data.server_key->rsa->n),
1769 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1770 SSH_KEY_BITS_RESERVED);
1772 if (rsa_private_decrypt(session_key_int, session_key_int,
1773 sensitive_data.server_key->rsa) <= 0)
1775 if (rsa_private_decrypt(session_key_int, session_key_int,
1776 sensitive_data.ssh1_host_key->rsa) <= 0)
1779 /* Host key has bigger modulus (or they are equal). */
1780 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1781 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1782 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1783 get_remote_ipaddr(),
1784 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1785 BN_num_bits(sensitive_data.server_key->rsa->n),
1786 SSH_KEY_BITS_RESERVED);
1788 if (rsa_private_decrypt(session_key_int, session_key_int,
1789 sensitive_data.ssh1_host_key->rsa) < 0)
1791 if (rsa_private_decrypt(session_key_int, session_key_int,
1792 sensitive_data.server_key->rsa) < 0)
1805 BIGNUM *session_key_int;
1806 u_char session_key[SSH_SESSION_KEY_LENGTH];
1808 u_int cipher_type, auth_mask, protocol_flags;
1812 * Generate check bytes that the client must send back in the user
1813 * packet in order for it to be accepted; this is used to defy ip
1814 * spoofing attacks. Note that this only works against somebody
1815 * doing IP spoofing from a remote machine; any machine on the local
1816 * network can still see outgoing packets and catch the random
1817 * cookie. This only affects rhosts authentication, and this is one
1818 * of the reasons why it is inherently insecure.
1820 for (i = 0; i < 8; i++) {
1823 cookie[i] = rnd & 0xff;
1828 * Send our public key. We include in the packet 64 bits of random
1829 * data that must be matched in the reply in order to prevent IP
1832 packet_start(SSH_SMSG_PUBLIC_KEY);
1833 for (i = 0; i < 8; i++)
1834 packet_put_char(cookie[i]);
1836 /* Store our public server RSA key. */
1837 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1838 packet_put_bignum(sensitive_data.server_key->rsa->e);
1839 packet_put_bignum(sensitive_data.server_key->rsa->n);
1841 /* Store our public host RSA key. */
1842 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1843 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1844 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1846 /* Put protocol flags. */
1847 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1849 /* Declare which ciphers we support. */
1850 packet_put_int(cipher_mask_ssh1(0));
1852 /* Declare supported authentication types. */
1854 if (options.rhosts_rsa_authentication)
1855 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1856 if (options.rsa_authentication)
1857 auth_mask |= 1 << SSH_AUTH_RSA;
1858 if (options.challenge_response_authentication == 1)
1859 auth_mask |= 1 << SSH_AUTH_TIS;
1860 if (options.password_authentication)
1861 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1862 packet_put_int(auth_mask);
1864 /* Send the packet and wait for it to be sent. */
1866 packet_write_wait();
1868 debug("Sent %d bit server key and %d bit host key.",
1869 BN_num_bits(sensitive_data.server_key->rsa->n),
1870 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1872 /* Read clients reply (cipher type and session key). */
1873 packet_read_expect(SSH_CMSG_SESSION_KEY);
1875 /* Get cipher type and check whether we accept this. */
1876 cipher_type = packet_get_char();
1878 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1879 packet_disconnect("Warning: client selects unsupported cipher.");
1881 /* Get check bytes from the packet. These must match those we
1882 sent earlier with the public key packet. */
1883 for (i = 0; i < 8; i++)
1884 if (cookie[i] != packet_get_char())
1885 packet_disconnect("IP Spoofing check bytes do not match.");
1887 debug("Encryption type: %.200s", cipher_name(cipher_type));
1889 /* Get the encrypted integer. */
1890 if ((session_key_int = BN_new()) == NULL)
1891 fatal("do_ssh1_kex: BN_new failed");
1892 packet_get_bignum(session_key_int);
1894 protocol_flags = packet_get_int();
1895 packet_set_protocol_flags(protocol_flags);
1898 /* Decrypt session_key_int using host/server keys */
1899 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1902 * Extract session key from the decrypted integer. The key is in the
1903 * least significant 256 bits of the integer; the first byte of the
1904 * key is in the highest bits.
1907 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1908 len = BN_num_bytes(session_key_int);
1909 if (len < 0 || len > sizeof(session_key)) {
1910 error("do_connection: bad session key len from %s: "
1911 "session_key_int %d > sizeof(session_key) %lu",
1912 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1915 memset(session_key, 0, sizeof(session_key));
1916 BN_bn2bin(session_key_int,
1917 session_key + sizeof(session_key) - len);
1919 derive_ssh1_session_id(
1920 sensitive_data.ssh1_host_key->rsa->n,
1921 sensitive_data.server_key->rsa->n,
1922 cookie, session_id);
1924 * Xor the first 16 bytes of the session key with the
1927 for (i = 0; i < 16; i++)
1928 session_key[i] ^= session_id[i];
1932 int bytes = BN_num_bytes(session_key_int);
1933 u_char *buf = xmalloc(bytes);
1936 logit("do_connection: generating a fake encryption key");
1937 BN_bn2bin(session_key_int, buf);
1939 MD5_Update(&md, buf, bytes);
1940 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1941 MD5_Final(session_key, &md);
1943 MD5_Update(&md, session_key, 16);
1944 MD5_Update(&md, buf, bytes);
1945 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1946 MD5_Final(session_key + 16, &md);
1947 memset(buf, 0, bytes);
1949 for (i = 0; i < 16; i++)
1950 session_id[i] = session_key[i] ^ session_key[i + 16];
1952 /* Destroy the private and public keys. No longer. */
1953 destroy_sensitive_data();
1956 mm_ssh1_session_id(session_id);
1958 /* Destroy the decrypted integer. It is no longer needed. */
1959 BN_clear_free(session_key_int);
1961 /* Set the session key. From this on all communications will be encrypted. */
1962 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1964 /* Destroy our copy of the session key. It is no longer needed. */
1965 memset(session_key, 0, sizeof(session_key));
1967 debug("Received session key; encryption turned on.");
1969 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1970 packet_start(SSH_SMSG_SUCCESS);
1972 packet_write_wait();
1976 * SSH2 key exchange: diffie-hellman-group1-sha1
1983 if (options.ciphers != NULL) {
1984 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1985 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1987 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1988 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1989 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1990 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1992 if (options.macs != NULL) {
1993 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1994 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1996 if (!options.compression) {
1997 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1998 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2000 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2002 /* start key exchange */
2003 kex = kex_setup(myproposal);
2004 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2005 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2006 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2008 kex->client_version_string=client_version_string;
2009 kex->server_version_string=server_version_string;
2010 kex->load_host_key=&get_hostkey_by_type;
2011 kex->host_key_index=&get_hostkey_index;
2015 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2017 session_id2 = kex->session_id;
2018 session_id2_len = kex->session_id_len;
2021 /* send 1st encrypted/maced/compressed message */
2022 packet_start(SSH2_MSG_IGNORE);
2023 packet_put_cstring("markus");
2025 packet_write_wait();
2030 /* server specific fatal cleanup */
2035 do_cleanup(the_authctxt);