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 1.299 2004/07/17 05:31:41 dtucker Exp $");
47 #include <openssl/dh.h>
48 #include <openssl/bn.h>
49 #include <openssl/md5.h>
50 #include <openssl/rand.h>
51 #ifdef HAVE_SECUREWARE
52 #include <sys/security.h>
73 #include "myproposal.h"
75 #include "pathnames.h"
84 #include "monitor_mm.h"
86 #include "monitor_wrap.h"
87 #include "monitor_fdpass.h"
92 int allow_severity = LOG_INFO;
93 int deny_severity = LOG_WARNING;
101 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
102 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
103 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
104 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
106 extern char *__progname;
108 /* Server configuration options. */
109 ServerOptions options;
111 /* Name of the server configuration file. */
112 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
115 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
116 * Default value is AF_UNSPEC means both IPv4 and IPv6.
118 int IPv4or6 = AF_UNSPEC;
121 * Debug mode flag. This can be set on the command line. If debug
122 * mode is enabled, extra debugging output will be sent to the system
123 * log, the daemon will not go to background, and will exit after processing
124 * the first connection.
128 /* Flag indicating that the daemon should only test the configuration and keys. */
131 /* Flag indicating that the daemon is being started from inetd. */
134 /* Flag indicating that sshd should not detach and become a daemon. */
135 int no_daemon_flag = 0;
137 /* debug goes to stderr unless inetd_flag is set */
140 /* Saved arguments to main(). */
145 int rexeced_flag = 0;
151 * The sockets that the server is listening; this is used in the SIGHUP
154 #define MAX_LISTEN_SOCKS 16
155 int listen_socks[MAX_LISTEN_SOCKS];
156 int num_listen_socks = 0;
159 * the client's version string, passed by sshd2 in compat mode. if != NULL,
160 * sshd will skip the version-number exchange
162 char *client_version_string = NULL;
163 char *server_version_string = NULL;
165 /* for rekeying XXX fixme */
169 * Any really sensitive data in the application is contained in this
170 * structure. The idea is that this structure could be locked into memory so
171 * that the pages do not get written into swap. However, there are some
172 * problems. The private key contains BIGNUMs, and we do not (in principle)
173 * have access to the internals of them, and locking just the structure is
174 * not very useful. Currently, memory locking is not implemented.
177 Key *server_key; /* ephemeral server key */
178 Key *ssh1_host_key; /* ssh1 host key */
179 Key **host_keys; /* all private host keys */
182 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
186 * Flag indicating whether the RSA server key needs to be regenerated.
187 * Is set in the SIGALRM handler and cleared when the key is regenerated.
189 static volatile sig_atomic_t key_do_regen = 0;
191 /* This is set to true when a signal is received. */
192 static volatile sig_atomic_t received_sighup = 0;
193 static volatile sig_atomic_t received_sigterm = 0;
195 /* session identifier, used by RSA-auth */
196 u_char session_id[16];
199 u_char *session_id2 = NULL;
200 u_int session_id2_len = 0;
202 /* record remote hostname or ip */
203 u_int utmp_len = MAXHOSTNAMELEN;
205 /* options.max_startup sized array of fd ints */
206 int *startup_pipes = NULL;
207 int startup_pipe; /* in child */
209 /* variables used for privilege separation */
211 struct monitor *pmonitor = NULL;
213 /* message to be displayed after login */
216 /* global authentication context */
217 Authctxt *the_authctxt = NULL;
219 /* message to be displayed after login */
222 /* Prototypes for various functions defined later in this file. */
223 void destroy_sensitive_data(void);
224 void demote_sensitive_data(void);
226 static void do_ssh1_kex(void);
227 static void do_ssh2_kex(void);
230 * Close all listening sockets
233 close_listen_socks(void)
237 for (i = 0; i < num_listen_socks; i++)
238 close(listen_socks[i]);
239 num_listen_socks = -1;
243 close_startup_pipes(void)
248 for (i = 0; i < options.max_startups; i++)
249 if (startup_pipes[i] != -1)
250 close(startup_pipes[i]);
254 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
255 * the effect is to reread the configuration file (and to regenerate
259 sighup_handler(int sig)
261 int save_errno = errno;
264 signal(SIGHUP, sighup_handler);
269 * Called from the main program after receiving SIGHUP.
270 * Restarts the server.
275 logit("Received SIGHUP; restarting.");
276 close_listen_socks();
277 close_startup_pipes();
278 execv(saved_argv[0], saved_argv);
279 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
285 * Generic signal handler for terminating signals in the master daemon.
288 sigterm_handler(int sig)
290 received_sigterm = sig;
294 * SIGCHLD handler. This is called whenever a child dies. This will then
295 * reap any zombies left by exited children.
298 main_sigchld_handler(int sig)
300 int save_errno = errno;
304 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
305 (pid < 0 && errno == EINTR))
308 signal(SIGCHLD, main_sigchld_handler);
313 * Signal handler for the alarm after the login grace period has expired.
316 grace_alarm_handler(int sig)
318 /* XXX no idea how fix this signal handler */
320 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
321 kill(pmonitor->m_pid, SIGALRM);
323 /* Log error and exit. */
324 fatal("Timeout before authentication for %s", get_remote_ipaddr());
328 * Signal handler for the key regeneration alarm. Note that this
329 * alarm only occurs in the daemon waiting for connections, and it does not
330 * do anything with the private key or random state before forking.
331 * Thus there should be no concurrency control/asynchronous execution
335 generate_ephemeral_server_key(void)
340 verbose("Generating %s%d bit RSA key.",
341 sensitive_data.server_key ? "new " : "", options.server_key_bits);
342 if (sensitive_data.server_key != NULL)
343 key_free(sensitive_data.server_key);
344 sensitive_data.server_key = key_generate(KEY_RSA1,
345 options.server_key_bits);
346 verbose("RSA key generation complete.");
348 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
351 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
358 key_regeneration_alarm(int sig)
360 int save_errno = errno;
362 signal(SIGALRM, SIG_DFL);
368 sshd_exchange_identification(int sock_in, int sock_out)
371 int remote_major, remote_minor;
374 char buf[256]; /* Must not be larger than remote_version. */
375 char remote_version[256]; /* Must be at least as big as buf. */
377 if ((options.protocol & SSH_PROTO_1) &&
378 (options.protocol & SSH_PROTO_2)) {
379 major = PROTOCOL_MAJOR_1;
381 } else if (options.protocol & SSH_PROTO_2) {
382 major = PROTOCOL_MAJOR_2;
383 minor = PROTOCOL_MINOR_2;
385 major = PROTOCOL_MAJOR_1;
386 minor = PROTOCOL_MINOR_1;
388 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
389 server_version_string = xstrdup(buf);
391 /* Send our protocol version identification. */
392 if (atomicio(vwrite, sock_out, server_version_string,
393 strlen(server_version_string))
394 != strlen(server_version_string)) {
395 logit("Could not write ident string to %s", get_remote_ipaddr());
399 /* Read other sides version identification. */
400 memset(buf, 0, sizeof(buf));
401 for (i = 0; i < sizeof(buf) - 1; i++) {
402 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
403 logit("Did not receive identification string from %s",
404 get_remote_ipaddr());
407 if (buf[i] == '\r') {
409 /* Kludge for F-Secure Macintosh < 1.0.2 */
411 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
415 if (buf[i] == '\n') {
420 buf[sizeof(buf) - 1] = 0;
421 client_version_string = xstrdup(buf);
424 * Check that the versions match. In future this might accept
425 * several versions and set appropriate flags to handle them.
427 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
428 &remote_major, &remote_minor, remote_version) != 3) {
429 s = "Protocol mismatch.\n";
430 (void) atomicio(vwrite, sock_out, s, strlen(s));
433 logit("Bad protocol version identification '%.100s' from %s",
434 client_version_string, get_remote_ipaddr());
437 debug("Client protocol version %d.%d; client software version %.100s",
438 remote_major, remote_minor, remote_version);
440 compat_datafellows(remote_version);
442 if (datafellows & SSH_BUG_PROBE) {
443 logit("probed from %s with %s. Don't panic.",
444 get_remote_ipaddr(), client_version_string);
448 if (datafellows & SSH_BUG_SCANNER) {
449 logit("scanned from %s with %s. Don't panic.",
450 get_remote_ipaddr(), client_version_string);
455 switch (remote_major) {
457 if (remote_minor == 99) {
458 if (options.protocol & SSH_PROTO_2)
464 if (!(options.protocol & SSH_PROTO_1)) {
468 if (remote_minor < 3) {
469 packet_disconnect("Your ssh version is too old and "
470 "is no longer supported. Please install a newer version.");
471 } else if (remote_minor == 3) {
472 /* note that this disables agent-forwarding */
477 if (options.protocol & SSH_PROTO_2) {
486 chop(server_version_string);
487 debug("Local version string %.200s", server_version_string);
490 s = "Protocol major versions differ.\n";
491 (void) atomicio(vwrite, sock_out, s, strlen(s));
494 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
496 server_version_string, client_version_string);
501 /* Destroy the host and server keys. They will no longer be needed. */
503 destroy_sensitive_data(void)
507 if (sensitive_data.server_key) {
508 key_free(sensitive_data.server_key);
509 sensitive_data.server_key = NULL;
511 for (i = 0; i < options.num_host_key_files; i++) {
512 if (sensitive_data.host_keys[i]) {
513 key_free(sensitive_data.host_keys[i]);
514 sensitive_data.host_keys[i] = NULL;
517 sensitive_data.ssh1_host_key = NULL;
518 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
521 /* Demote private to public keys for network child */
523 demote_sensitive_data(void)
528 if (sensitive_data.server_key) {
529 tmp = key_demote(sensitive_data.server_key);
530 key_free(sensitive_data.server_key);
531 sensitive_data.server_key = tmp;
534 for (i = 0; i < options.num_host_key_files; i++) {
535 if (sensitive_data.host_keys[i]) {
536 tmp = key_demote(sensitive_data.host_keys[i]);
537 key_free(sensitive_data.host_keys[i]);
538 sensitive_data.host_keys[i] = tmp;
539 if (tmp->type == KEY_RSA1)
540 sensitive_data.ssh1_host_key = tmp;
544 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
548 privsep_preauth_child(void)
555 /* Enable challenge-response authentication for privilege separation */
556 privsep_challenge_enable();
558 for (i = 0; i < 256; i++)
559 rnd[i] = arc4random();
560 RAND_seed(rnd, sizeof(rnd));
562 /* Demote the private keys to public keys. */
563 demote_sensitive_data();
565 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
566 fatal("Privilege separation user %s does not exist",
568 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
571 /* Change our root directory */
572 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
573 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
575 if (chdir("/") == -1)
576 fatal("chdir(\"/\"): %s", strerror(errno));
578 /* Drop our privileges */
579 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
582 /* XXX not ready, too heavy after chroot */
583 do_setusercontext(pw);
585 gidset[0] = pw->pw_gid;
586 if (setgroups(1, gidset) < 0)
587 fatal("setgroups: %.100s", strerror(errno));
588 permanently_set_uid(pw);
593 privsep_preauth(Authctxt *authctxt)
598 /* Set up unprivileged child process to deal with network data */
599 pmonitor = monitor_init();
600 /* Store a pointer to the kex for later rekeying */
601 pmonitor->m_pkex = &xxx_kex;
605 fatal("fork of unprivileged child failed");
606 } else if (pid != 0) {
607 debug2("Network child is on pid %ld", (long)pid);
609 close(pmonitor->m_recvfd);
610 pmonitor->m_pid = pid;
611 monitor_child_preauth(authctxt, pmonitor);
612 close(pmonitor->m_sendfd);
615 monitor_sync(pmonitor);
617 /* Wait for the child's exit status */
618 while (waitpid(pid, &status, 0) < 0)
625 close(pmonitor->m_sendfd);
627 /* Demote the child */
628 if (getuid() == 0 || geteuid() == 0)
629 privsep_preauth_child();
630 setproctitle("%s", "[net]");
636 privsep_postauth(Authctxt *authctxt)
638 #ifdef DISABLE_FD_PASSING
641 if (authctxt->pw->pw_uid == 0 || options.use_login) {
643 /* File descriptor passing is broken or root login */
644 monitor_apply_keystate(pmonitor);
649 /* Authentication complete */
651 if (startup_pipe != -1) {
656 /* New socket pair */
657 monitor_reinit(pmonitor);
659 pmonitor->m_pid = fork();
660 if (pmonitor->m_pid == -1)
661 fatal("fork of unprivileged child failed");
662 else if (pmonitor->m_pid != 0) {
663 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
664 close(pmonitor->m_recvfd);
665 monitor_child_postauth(pmonitor);
671 close(pmonitor->m_sendfd);
673 /* Demote the private keys to public keys. */
674 demote_sensitive_data();
676 /* Drop privileges */
677 do_setusercontext(authctxt->pw);
679 /* It is safe now to apply the key state */
680 monitor_apply_keystate(pmonitor);
684 list_hostkey_types(void)
692 for (i = 0; i < options.num_host_key_files; i++) {
693 Key *key = sensitive_data.host_keys[i];
699 if (buffer_len(&b) > 0)
700 buffer_append(&b, ",", 1);
701 p = key_ssh_name(key);
702 buffer_append(&b, p, strlen(p));
706 buffer_append(&b, "\0", 1);
707 ret = xstrdup(buffer_ptr(&b));
709 debug("list_hostkey_types: %s", ret);
714 get_hostkey_by_type(int type)
718 for (i = 0; i < options.num_host_key_files; i++) {
719 Key *key = sensitive_data.host_keys[i];
720 if (key != NULL && key->type == type)
727 get_hostkey_by_index(int ind)
729 if (ind < 0 || ind >= options.num_host_key_files)
731 return (sensitive_data.host_keys[ind]);
735 get_hostkey_index(Key *key)
739 for (i = 0; i < options.num_host_key_files; i++) {
740 if (key == sensitive_data.host_keys[i])
747 * returns 1 if connection should be dropped, 0 otherwise.
748 * dropping starts at connection #max_startups_begin with a probability
749 * of (max_startups_rate/100). the probability increases linearly until
750 * all connections are dropped for startups > max_startups
753 drop_connection(int startups)
757 if (startups < options.max_startups_begin)
759 if (startups >= options.max_startups)
761 if (options.max_startups_rate == 100)
764 p = 100 - options.max_startups_rate;
765 p *= startups - options.max_startups_begin;
766 p /= (double) (options.max_startups - options.max_startups_begin);
767 p += options.max_startups_rate;
769 r = arc4random() / (double) UINT_MAX;
771 debug("drop_connection: p %g, r %g", p, r);
772 return (r < p) ? 1 : 0;
778 fprintf(stderr, "%s, %s\n",
779 SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
781 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
782 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
788 send_rexec_state(int fd, Buffer *conf)
792 debug3("%s: entering fd = %d config len %d", __func__, fd,
796 * Protocol from reexec master to child:
797 * string configuration
798 * u_int ephemeral_key_follows
799 * bignum e (only if ephemeral_key_follows == 1)
807 buffer_put_cstring(&m, buffer_ptr(conf));
809 if (sensitive_data.server_key != NULL &&
810 sensitive_data.server_key->type == KEY_RSA1) {
811 buffer_put_int(&m, 1);
812 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
813 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
814 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
815 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
816 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
817 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
819 buffer_put_int(&m, 0);
821 if (ssh_msg_send(fd, 0, &m) == -1)
822 fatal("%s: ssh_msg_send failed", __func__);
826 debug3("%s: done", __func__);
830 recv_rexec_state(int fd, Buffer *conf)
836 debug3("%s: entering fd = %d", __func__, fd);
840 if (ssh_msg_recv(fd, &m) == -1)
841 fatal("%s: ssh_msg_recv failed", __func__);
842 if (buffer_get_char(&m) != 0)
843 fatal("%s: rexec version mismatch", __func__);
845 cp = buffer_get_string(&m, &len);
847 buffer_append(conf, cp, len + 1);
850 if (buffer_get_int(&m)) {
851 if (sensitive_data.server_key != NULL)
852 key_free(sensitive_data.server_key);
853 sensitive_data.server_key = key_new_private(KEY_RSA1);
854 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
855 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
856 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
857 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
858 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
859 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
860 rsa_generate_additional_parameters(
861 sensitive_data.server_key->rsa);
865 debug3("%s: done", __func__);
869 * Main program for the daemon.
872 main(int ac, char **av)
876 int opt, j, i, fdsetsz, on = 1;
877 int sock_in = -1, sock_out = -1, newsock = -1;
881 struct sockaddr_storage from;
882 const char *remote_ip;
886 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
888 int listen_sock, maxfd;
889 int startup_p[2], config_s[2];
893 int ret, key_used = 0;
896 #ifdef HAVE_SECUREWARE
897 (void)set_auth_parameters(ac, av);
899 __progname = ssh_get_progname(av[0]);
902 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
905 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
906 for (i = 0; i < ac; i++)
907 saved_argv[i] = xstrdup(av[i]);
908 saved_argv[i] = NULL;
910 #ifndef HAVE_SETPROCTITLE
911 /* Prepare for later setproctitle emulation */
912 compat_init_setproctitle(ac, av);
916 if (geteuid() == 0 && setgroups(0, NULL) == -1)
917 debug("setgroups(): %.200s", strerror(errno));
919 /* Initialize configuration options to their default values. */
920 initialize_server_options(&options);
922 /* Parse command-line arguments. */
923 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
932 config_file_name = optarg;
935 if (debug_flag == 0) {
937 options.log_level = SYSLOG_LEVEL_DEBUG1;
938 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
961 options.log_level = SYSLOG_LEVEL_QUIET;
964 options.server_key_bits = atoi(optarg);
967 options.ports_from_cmdline = 1;
968 if (options.num_ports >= MAX_PORTS) {
969 fprintf(stderr, "too many ports.\n");
972 options.ports[options.num_ports++] = a2port(optarg);
973 if (options.ports[options.num_ports-1] == 0) {
974 fprintf(stderr, "Bad port number.\n");
979 if ((options.login_grace_time = convtime(optarg)) == -1) {
980 fprintf(stderr, "Invalid login grace time.\n");
985 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
986 fprintf(stderr, "Invalid key regeneration interval.\n");
991 if (options.num_host_key_files >= MAX_HOSTKEYS) {
992 fprintf(stderr, "too many host keys.\n");
995 options.host_key_files[options.num_host_key_files++] = optarg;
1001 utmp_len = atoi(optarg);
1002 if (utmp_len > MAXHOSTNAMELEN) {
1003 fprintf(stderr, "Invalid utmp length.\n");
1008 line = xstrdup(optarg);
1009 if (process_server_config_line(&options, line,
1010 "command-line", 0) != 0)
1020 if (rexeced_flag || inetd_flag)
1022 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1023 fatal("sshd re-exec requires execution with an absolute path");
1025 closefrom(REEXEC_MIN_FREE_FD);
1027 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1029 SSLeay_add_all_algorithms();
1030 channel_set_af(IPv4or6);
1033 * Force logging to stderr until we have loaded the private host
1034 * key (unless started from inetd)
1036 log_init(__progname,
1037 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1038 SYSLOG_LEVEL_INFO : options.log_level,
1039 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1040 SYSLOG_FACILITY_AUTH : options.log_facility,
1041 log_stderr || !inetd_flag);
1045 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1046 * root's environment
1048 unsetenv("KRB5CCNAME");
1051 /* Cray can define user privs drop all privs now!
1052 * Not needed on PRIV_SU systems!
1059 sensitive_data.server_key = NULL;
1060 sensitive_data.ssh1_host_key = NULL;
1061 sensitive_data.have_ssh1_key = 0;
1062 sensitive_data.have_ssh2_key = 0;
1064 /* Fetch our configuration */
1067 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1069 load_server_config(config_file_name, &cfg);
1071 parse_server_config(&options,
1072 rexeced_flag ? "rexec" : config_file_name, &cfg);
1077 /* Fill in default values for those options not explicitly set. */
1078 fill_default_server_options(&options);
1080 /* Check that there are no remaining arguments. */
1082 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1086 debug("sshd version %.100s", SSH_VERSION);
1088 /* load private host keys */
1089 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1091 for (i = 0; i < options.num_host_key_files; i++)
1092 sensitive_data.host_keys[i] = NULL;
1094 for (i = 0; i < options.num_host_key_files; i++) {
1095 key = key_load_private(options.host_key_files[i], "", NULL);
1096 sensitive_data.host_keys[i] = key;
1098 error("Could not load host key: %s",
1099 options.host_key_files[i]);
1100 sensitive_data.host_keys[i] = NULL;
1103 switch (key->type) {
1105 sensitive_data.ssh1_host_key = key;
1106 sensitive_data.have_ssh1_key = 1;
1110 sensitive_data.have_ssh2_key = 1;
1113 debug("private host key: #%d type %d %s", i, key->type,
1116 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1117 logit("Disabling protocol version 1. Could not load host key");
1118 options.protocol &= ~SSH_PROTO_1;
1120 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1121 logit("Disabling protocol version 2. Could not load host key");
1122 options.protocol &= ~SSH_PROTO_2;
1124 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1125 logit("sshd: no hostkeys available -- exiting.");
1129 /* Check certain values for sanity. */
1130 if (options.protocol & SSH_PROTO_1) {
1131 if (options.server_key_bits < 512 ||
1132 options.server_key_bits > 32768) {
1133 fprintf(stderr, "Bad server key size.\n");
1137 * Check that server and host key lengths differ sufficiently. This
1138 * is necessary to make double encryption work with rsaref. Oh, I
1139 * hate software patents. I dont know if this can go? Niels
1141 if (options.server_key_bits >
1142 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1143 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1144 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1145 SSH_KEY_BITS_RESERVED) {
1146 options.server_key_bits =
1147 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1148 SSH_KEY_BITS_RESERVED;
1149 debug("Forcing server key to %d bits to make it differ from host key.",
1150 options.server_key_bits);
1158 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1159 fatal("Privilege separation user %s does not exist",
1161 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1162 (S_ISDIR(st.st_mode) == 0))
1163 fatal("Missing privilege separation directory: %s",
1164 _PATH_PRIVSEP_CHROOT_DIR);
1167 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1168 (st.st_uid != getuid () ||
1169 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1171 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1173 fatal("%s must be owned by root and not group or "
1174 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1177 /* Configuration looks good, so exit if in test mode. */
1182 * Clear out any supplemental groups we may have inherited. This
1183 * prevents inadvertent creation of files with bad modes (in the
1184 * portable version at least, it's certainly possible for PAM
1185 * to create a file, and we can't control the code in every
1186 * module which might be used).
1188 if (setgroups(0, NULL) < 0)
1189 debug("setgroups() failed: %.200s", strerror(errno));
1192 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1193 for (i = 0; i < rexec_argc; i++) {
1194 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1195 rexec_argv[i] = saved_argv[i];
1197 rexec_argv[rexec_argc] = "-R";
1198 rexec_argv[rexec_argc + 1] = NULL;
1201 /* Initialize the log (it is reinitialized below in case we forked). */
1202 if (debug_flag && !inetd_flag)
1204 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1207 * If not in debugging mode, and not started from inetd, disconnect
1208 * from the controlling terminal, and fork. The original process
1211 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1214 #endif /* TIOCNOTTY */
1215 if (daemon(0, 0) < 0)
1216 fatal("daemon() failed: %.200s", strerror(errno));
1218 /* Disconnect from the controlling tty. */
1220 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1222 (void) ioctl(fd, TIOCNOTTY, NULL);
1225 #endif /* TIOCNOTTY */
1227 /* Reinitialize the log (because of the fork above). */
1228 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1230 /* Initialize the random number generator. */
1233 /* Chdir to the root directory so that the current disk can be
1234 unmounted if desired. */
1237 /* ignore SIGPIPE */
1238 signal(SIGPIPE, SIG_IGN);
1240 /* Start listening for a socket, unless started from inetd. */
1246 close(REEXEC_CONFIG_PASS_FD);
1247 sock_in = sock_out = dup(STDIN_FILENO);
1249 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1250 close(REEXEC_STARTUP_PIPE_FD);
1253 sock_in = dup(STDIN_FILENO);
1254 sock_out = dup(STDOUT_FILENO);
1257 * We intentionally do not close the descriptors 0, 1, and 2
1258 * as our code for setting the descriptors won't work if
1259 * ttyfd happens to be one of those.
1261 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1262 dup2(fd, STDIN_FILENO);
1263 dup2(fd, STDOUT_FILENO);
1264 if (fd > STDOUT_FILENO)
1267 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1268 if ((options.protocol & SSH_PROTO_1) &&
1269 sensitive_data.server_key == NULL)
1270 generate_ephemeral_server_key();
1272 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1273 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1275 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1276 fatal("Too many listen sockets. "
1277 "Enlarge MAX_LISTEN_SOCKS");
1278 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1279 ntop, sizeof(ntop), strport, sizeof(strport),
1280 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1281 error("getnameinfo failed");
1284 /* Create socket for listening. */
1285 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1287 if (listen_sock < 0) {
1288 /* kernel may not support ipv6 */
1289 verbose("socket: %.100s", strerror(errno));
1292 if (set_nonblock(listen_sock) == -1) {
1297 * Set socket options.
1298 * Allow local port reuse in TIME_WAIT.
1300 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1301 &on, sizeof(on)) == -1)
1302 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1304 debug("Bind to port %s on %s.", strport, ntop);
1306 /* Bind the socket to the desired port. */
1307 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1309 error("Bind to port %s on %s failed: %.200s.",
1310 strport, ntop, strerror(errno));
1314 listen_socks[num_listen_socks] = listen_sock;
1317 /* Start listening on the port. */
1318 logit("Server listening on %s port %s.", ntop, strport);
1319 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1320 fatal("listen: %.100s", strerror(errno));
1323 freeaddrinfo(options.listen_addrs);
1325 if (!num_listen_socks)
1326 fatal("Cannot bind any address.");
1328 if (options.protocol & SSH_PROTO_1)
1329 generate_ephemeral_server_key();
1332 * Arrange to restart on SIGHUP. The handler needs
1335 signal(SIGHUP, sighup_handler);
1337 signal(SIGTERM, sigterm_handler);
1338 signal(SIGQUIT, sigterm_handler);
1340 /* Arrange SIGCHLD to be caught. */
1341 signal(SIGCHLD, main_sigchld_handler);
1343 /* Write out the pid file after the sigterm handler is setup */
1346 * Record our pid in /var/run/sshd.pid to make it
1347 * easier to kill the correct sshd. We don't want to
1348 * do this before the bind above because the bind will
1349 * fail if there already is a daemon, and this will
1350 * overwrite any old pid in the file.
1352 f = fopen(options.pid_file, "wb");
1354 error("Couldn't create pid file \"%s\": %s",
1355 options.pid_file, strerror(errno));
1357 fprintf(f, "%ld\n", (long) getpid());
1362 /* setup fd set for listen */
1365 for (i = 0; i < num_listen_socks; i++)
1366 if (listen_socks[i] > maxfd)
1367 maxfd = listen_socks[i];
1368 /* pipes connected to unauthenticated childs */
1369 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1370 for (i = 0; i < options.max_startups; i++)
1371 startup_pipes[i] = -1;
1374 * Stay listening for connections until the system crashes or
1375 * the daemon is killed with a signal.
1378 if (received_sighup)
1382 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1383 fdset = (fd_set *)xmalloc(fdsetsz);
1384 memset(fdset, 0, fdsetsz);
1386 for (i = 0; i < num_listen_socks; i++)
1387 FD_SET(listen_socks[i], fdset);
1388 for (i = 0; i < options.max_startups; i++)
1389 if (startup_pipes[i] != -1)
1390 FD_SET(startup_pipes[i], fdset);
1392 /* Wait in select until there is a connection. */
1393 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1394 if (ret < 0 && errno != EINTR)
1395 error("select: %.100s", strerror(errno));
1396 if (received_sigterm) {
1397 logit("Received signal %d; terminating.",
1398 (int) received_sigterm);
1399 close_listen_socks();
1400 unlink(options.pid_file);
1403 if (key_used && key_do_regen) {
1404 generate_ephemeral_server_key();
1411 for (i = 0; i < options.max_startups; i++)
1412 if (startup_pipes[i] != -1 &&
1413 FD_ISSET(startup_pipes[i], fdset)) {
1415 * the read end of the pipe is ready
1416 * if the child has closed the pipe
1417 * after successful authentication
1418 * or if the child has died
1420 close(startup_pipes[i]);
1421 startup_pipes[i] = -1;
1424 for (i = 0; i < num_listen_socks; i++) {
1425 if (!FD_ISSET(listen_socks[i], fdset))
1427 fromlen = sizeof(from);
1428 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1431 if (errno != EINTR && errno != EWOULDBLOCK)
1432 error("accept: %.100s", strerror(errno));
1435 if (unset_nonblock(newsock) == -1) {
1439 if (drop_connection(startups) == 1) {
1440 debug("drop connection #%d", startups);
1444 if (pipe(startup_p) == -1) {
1449 if (rexec_flag && socketpair(AF_UNIX,
1450 SOCK_STREAM, 0, config_s) == -1) {
1451 error("reexec socketpair: %s",
1454 close(startup_p[0]);
1455 close(startup_p[1]);
1459 for (j = 0; j < options.max_startups; j++)
1460 if (startup_pipes[j] == -1) {
1461 startup_pipes[j] = startup_p[0];
1462 if (maxfd < startup_p[0])
1463 maxfd = startup_p[0];
1469 * Got connection. Fork a child to handle it, unless
1470 * we are in debugging mode.
1474 * In debugging mode. Close the listening
1475 * socket, and start processing the
1476 * connection without forking.
1478 debug("Server will not fork when running in debugging mode.");
1479 close_listen_socks();
1482 close(startup_p[0]);
1483 close(startup_p[1]);
1487 send_rexec_state(config_s[0],
1494 * Normal production daemon. Fork, and have
1495 * the child process the connection. The
1496 * parent continues listening.
1498 if ((pid = fork()) == 0) {
1500 * Child. Close the listening and max_startup
1501 * sockets. Start using the accepted socket.
1502 * Reinitialize logging (since our pid has
1503 * changed). We break out of the loop to handle
1506 startup_pipe = startup_p[1];
1507 close_startup_pipes();
1508 close_listen_socks();
1511 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1517 /* Parent. Stay in the loop. */
1519 error("fork: %.100s", strerror(errno));
1521 debug("Forked child %ld.", (long)pid);
1523 close(startup_p[1]);
1526 send_rexec_state(config_s[0], &cfg);
1531 /* Mark that the key has been used (it was "given" to the child). */
1532 if ((options.protocol & SSH_PROTO_1) &&
1534 /* Schedule server key regeneration alarm. */
1535 signal(SIGALRM, key_regeneration_alarm);
1536 alarm(options.key_regeneration_time);
1542 /* Close the new socket (the child is now taking care of it). */
1545 /* child process check (or debug mode) */
1546 if (num_listen_socks < 0)
1551 /* This is the child processing a new connection. */
1552 setproctitle("%s", "[accepted]");
1557 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1558 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1559 dup2(newsock, STDIN_FILENO);
1560 dup2(STDIN_FILENO, STDOUT_FILENO);
1561 if (startup_pipe == -1)
1562 close(REEXEC_STARTUP_PIPE_FD);
1564 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1566 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1568 close(startup_pipe);
1570 execv(rexec_argv[0], rexec_argv);
1572 /* Reexec has failed, fall back and continue */
1573 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1574 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1575 log_init(__progname, options.log_level,
1576 options.log_facility, log_stderr);
1579 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1581 close(REEXEC_CONFIG_PASS_FD);
1582 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1583 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1584 dup2(fd, STDIN_FILENO);
1585 dup2(fd, STDOUT_FILENO);
1586 if (fd > STDERR_FILENO)
1589 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1590 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1594 * Create a new session and process group since the 4.4BSD
1595 * setlogin() affects the entire process group. We don't
1596 * want the child to be able to affect the parent.
1598 #if !defined(SSHD_ACQUIRES_CTTY)
1600 * If setsid is called, on some platforms sshd will later acquire a
1601 * controlling terminal which will result in "could not set
1602 * controlling tty" errors.
1604 if (!debug_flag && !inetd_flag && setsid() < 0)
1605 error("setsid: %.100s", strerror(errno));
1609 * Disable the key regeneration alarm. We will not regenerate the
1610 * key since we are no longer in a position to give it to anyone. We
1611 * will not restart on SIGHUP since it no longer makes sense.
1614 signal(SIGALRM, SIG_DFL);
1615 signal(SIGHUP, SIG_DFL);
1616 signal(SIGTERM, SIG_DFL);
1617 signal(SIGQUIT, SIG_DFL);
1618 signal(SIGCHLD, SIG_DFL);
1619 signal(SIGINT, SIG_DFL);
1621 /* Set SO_KEEPALIVE if requested. */
1622 if (options.tcp_keep_alive &&
1623 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1625 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1628 * Register our connection. This turns encryption off because we do
1631 packet_set_connection(sock_in, sock_out);
1633 remote_port = get_remote_port();
1634 remote_ip = get_remote_ipaddr();
1637 /* Check whether logins are denied from this host. */
1638 if (packet_connection_is_on_socket()) {
1639 struct request_info req;
1641 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1644 if (!hosts_access(&req)) {
1645 debug("Connection refused by tcp wrapper");
1648 fatal("libwrap refuse returns");
1651 #endif /* LIBWRAP */
1653 /* Log the connection. */
1654 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1657 * We don\'t want to listen forever unless the other side
1658 * successfully authenticates itself. So we set up an alarm which is
1659 * cleared after successful authentication. A limit of zero
1660 * indicates no limit. Note that we don\'t set the alarm in debugging
1661 * mode; it is just annoying to have the server exit just when you
1662 * are about to discover the bug.
1664 signal(SIGALRM, grace_alarm_handler);
1666 alarm(options.login_grace_time);
1668 sshd_exchange_identification(sock_in, sock_out);
1670 packet_set_nonblocking();
1672 /* prepare buffers to collect authentication messages */
1673 buffer_init(&loginmsg);
1675 /* allocate authentication context */
1676 authctxt = xmalloc(sizeof(*authctxt));
1677 memset(authctxt, 0, sizeof(*authctxt));
1679 /* XXX global for cleanup, access from other modules */
1680 the_authctxt = authctxt;
1683 if (privsep_preauth(authctxt) == 1)
1686 /* prepare buffer to collect messages to display to user after login */
1687 buffer_init(&loginmsg);
1689 /* perform the key exchange */
1690 /* authenticate user and start session */
1693 do_authentication2(authctxt);
1696 do_authentication(authctxt);
1699 * If we use privilege separation, the unprivileged child transfers
1700 * the current keystate and exits
1703 mm_send_keystate(pmonitor);
1709 * In privilege separation, we fork another child and prepare
1710 * file descriptor passing.
1713 privsep_postauth(authctxt);
1714 /* the monitor process [priv] will not return */
1716 destroy_sensitive_data();
1719 /* Start session. */
1720 do_authenticated(authctxt);
1722 /* The connection has been terminated. */
1723 verbose("Closing connection to %.100s", remote_ip);
1726 if (options.use_pam)
1728 #endif /* USE_PAM */
1739 * Decrypt session_key_int using our private server key and private host key
1740 * (key with larger modulus first).
1743 ssh1_session_key(BIGNUM *session_key_int)
1747 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1748 /* Server key has bigger modulus. */
1749 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1750 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1751 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1752 get_remote_ipaddr(),
1753 BN_num_bits(sensitive_data.server_key->rsa->n),
1754 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1755 SSH_KEY_BITS_RESERVED);
1757 if (rsa_private_decrypt(session_key_int, session_key_int,
1758 sensitive_data.server_key->rsa) <= 0)
1760 if (rsa_private_decrypt(session_key_int, session_key_int,
1761 sensitive_data.ssh1_host_key->rsa) <= 0)
1764 /* Host key has bigger modulus (or they are equal). */
1765 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1766 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1767 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1768 get_remote_ipaddr(),
1769 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1770 BN_num_bits(sensitive_data.server_key->rsa->n),
1771 SSH_KEY_BITS_RESERVED);
1773 if (rsa_private_decrypt(session_key_int, session_key_int,
1774 sensitive_data.ssh1_host_key->rsa) < 0)
1776 if (rsa_private_decrypt(session_key_int, session_key_int,
1777 sensitive_data.server_key->rsa) < 0)
1790 BIGNUM *session_key_int;
1791 u_char session_key[SSH_SESSION_KEY_LENGTH];
1793 u_int cipher_type, auth_mask, protocol_flags;
1797 * Generate check bytes that the client must send back in the user
1798 * packet in order for it to be accepted; this is used to defy ip
1799 * spoofing attacks. Note that this only works against somebody
1800 * doing IP spoofing from a remote machine; any machine on the local
1801 * network can still see outgoing packets and catch the random
1802 * cookie. This only affects rhosts authentication, and this is one
1803 * of the reasons why it is inherently insecure.
1805 for (i = 0; i < 8; i++) {
1808 cookie[i] = rnd & 0xff;
1813 * Send our public key. We include in the packet 64 bits of random
1814 * data that must be matched in the reply in order to prevent IP
1817 packet_start(SSH_SMSG_PUBLIC_KEY);
1818 for (i = 0; i < 8; i++)
1819 packet_put_char(cookie[i]);
1821 /* Store our public server RSA key. */
1822 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1823 packet_put_bignum(sensitive_data.server_key->rsa->e);
1824 packet_put_bignum(sensitive_data.server_key->rsa->n);
1826 /* Store our public host RSA key. */
1827 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1828 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1829 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1831 /* Put protocol flags. */
1832 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1834 /* Declare which ciphers we support. */
1835 packet_put_int(cipher_mask_ssh1(0));
1837 /* Declare supported authentication types. */
1839 if (options.rhosts_rsa_authentication)
1840 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1841 if (options.rsa_authentication)
1842 auth_mask |= 1 << SSH_AUTH_RSA;
1843 if (options.challenge_response_authentication == 1)
1844 auth_mask |= 1 << SSH_AUTH_TIS;
1845 if (options.password_authentication)
1846 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1847 packet_put_int(auth_mask);
1849 /* Send the packet and wait for it to be sent. */
1851 packet_write_wait();
1853 debug("Sent %d bit server key and %d bit host key.",
1854 BN_num_bits(sensitive_data.server_key->rsa->n),
1855 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1857 /* Read clients reply (cipher type and session key). */
1858 packet_read_expect(SSH_CMSG_SESSION_KEY);
1860 /* Get cipher type and check whether we accept this. */
1861 cipher_type = packet_get_char();
1863 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1864 packet_disconnect("Warning: client selects unsupported cipher.");
1866 /* Get check bytes from the packet. These must match those we
1867 sent earlier with the public key packet. */
1868 for (i = 0; i < 8; i++)
1869 if (cookie[i] != packet_get_char())
1870 packet_disconnect("IP Spoofing check bytes do not match.");
1872 debug("Encryption type: %.200s", cipher_name(cipher_type));
1874 /* Get the encrypted integer. */
1875 if ((session_key_int = BN_new()) == NULL)
1876 fatal("do_ssh1_kex: BN_new failed");
1877 packet_get_bignum(session_key_int);
1879 protocol_flags = packet_get_int();
1880 packet_set_protocol_flags(protocol_flags);
1883 /* Decrypt session_key_int using host/server keys */
1884 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1887 * Extract session key from the decrypted integer. The key is in the
1888 * least significant 256 bits of the integer; the first byte of the
1889 * key is in the highest bits.
1892 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1893 len = BN_num_bytes(session_key_int);
1894 if (len < 0 || len > sizeof(session_key)) {
1895 error("do_connection: bad session key len from %s: "
1896 "session_key_int %d > sizeof(session_key) %lu",
1897 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1900 memset(session_key, 0, sizeof(session_key));
1901 BN_bn2bin(session_key_int,
1902 session_key + sizeof(session_key) - len);
1904 derive_ssh1_session_id(
1905 sensitive_data.ssh1_host_key->rsa->n,
1906 sensitive_data.server_key->rsa->n,
1907 cookie, session_id);
1909 * Xor the first 16 bytes of the session key with the
1912 for (i = 0; i < 16; i++)
1913 session_key[i] ^= session_id[i];
1917 int bytes = BN_num_bytes(session_key_int);
1918 u_char *buf = xmalloc(bytes);
1921 logit("do_connection: generating a fake encryption key");
1922 BN_bn2bin(session_key_int, buf);
1924 MD5_Update(&md, buf, bytes);
1925 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1926 MD5_Final(session_key, &md);
1928 MD5_Update(&md, session_key, 16);
1929 MD5_Update(&md, buf, bytes);
1930 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1931 MD5_Final(session_key + 16, &md);
1932 memset(buf, 0, bytes);
1934 for (i = 0; i < 16; i++)
1935 session_id[i] = session_key[i] ^ session_key[i + 16];
1937 /* Destroy the private and public keys. No longer. */
1938 destroy_sensitive_data();
1941 mm_ssh1_session_id(session_id);
1943 /* Destroy the decrypted integer. It is no longer needed. */
1944 BN_clear_free(session_key_int);
1946 /* Set the session key. From this on all communications will be encrypted. */
1947 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1949 /* Destroy our copy of the session key. It is no longer needed. */
1950 memset(session_key, 0, sizeof(session_key));
1952 debug("Received session key; encryption turned on.");
1954 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1955 packet_start(SSH_SMSG_SUCCESS);
1957 packet_write_wait();
1961 * SSH2 key exchange: diffie-hellman-group1-sha1
1968 if (options.ciphers != NULL) {
1969 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1970 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1972 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1973 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1974 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1975 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1977 if (options.macs != NULL) {
1978 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1979 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1981 if (!options.compression) {
1982 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1983 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1985 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1987 /* start key exchange */
1988 kex = kex_setup(myproposal);
1989 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1990 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1991 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1993 kex->client_version_string=client_version_string;
1994 kex->server_version_string=server_version_string;
1995 kex->load_host_key=&get_hostkey_by_type;
1996 kex->host_key_index=&get_hostkey_index;
2000 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2002 session_id2 = kex->session_id;
2003 session_id2_len = kex->session_id_len;
2006 /* send 1st encrypted/maced/compressed message */
2007 packet_start(SSH2_MSG_IGNORE);
2008 packet_put_cstring("markus");
2010 packet_write_wait();
2015 /* server specific fatal cleanup */
2020 do_cleanup(the_authctxt);