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 1.295 2004/06/25 01:16:09 djm 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;
100 #ifdef HAVE___PROGNAME
101 extern char *__progname;
106 /* Server configuration options. */
107 ServerOptions options;
109 /* Name of the server configuration file. */
110 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
113 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
114 * Default value is AF_UNSPEC means both IPv4 and IPv6.
116 int IPv4or6 = AF_UNSPEC;
119 * Debug mode flag. This can be set on the command line. If debug
120 * mode is enabled, extra debugging output will be sent to the system
121 * log, the daemon will not go to background, and will exit after processing
122 * the first connection.
126 /* Flag indicating that the daemon should only test the configuration and keys. */
129 /* Flag indicating that the daemon is being started from inetd. */
132 /* Flag indicating that sshd should not detach and become a daemon. */
133 int no_daemon_flag = 0;
135 /* debug goes to stderr unless inetd_flag is set */
138 /* Saved arguments to main(). */
143 int rexeced_flag = 0;
149 * The sockets that the server is listening; this is used in the SIGHUP
152 #define MAX_LISTEN_SOCKS 16
153 int listen_socks[MAX_LISTEN_SOCKS];
154 int num_listen_socks = 0;
157 * the client's version string, passed by sshd2 in compat mode. if != NULL,
158 * sshd will skip the version-number exchange
160 char *client_version_string = NULL;
161 char *server_version_string = NULL;
163 /* for rekeying XXX fixme */
167 * Any really sensitive data in the application is contained in this
168 * structure. The idea is that this structure could be locked into memory so
169 * that the pages do not get written into swap. However, there are some
170 * problems. The private key contains BIGNUMs, and we do not (in principle)
171 * have access to the internals of them, and locking just the structure is
172 * not very useful. Currently, memory locking is not implemented.
175 Key *server_key; /* ephemeral server key */
176 Key *ssh1_host_key; /* ssh1 host key */
177 Key **host_keys; /* all private host keys */
180 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
184 * Flag indicating whether the RSA server key needs to be regenerated.
185 * Is set in the SIGALRM handler and cleared when the key is regenerated.
187 static volatile sig_atomic_t key_do_regen = 0;
189 /* This is set to true when a signal is received. */
190 static volatile sig_atomic_t received_sighup = 0;
191 static volatile sig_atomic_t received_sigterm = 0;
193 /* session identifier, used by RSA-auth */
194 u_char session_id[16];
197 u_char *session_id2 = NULL;
198 u_int session_id2_len = 0;
200 /* record remote hostname or ip */
201 u_int utmp_len = MAXHOSTNAMELEN;
203 /* options.max_startup sized array of fd ints */
204 int *startup_pipes = NULL;
205 int startup_pipe; /* in child */
207 /* variables used for privilege separation */
209 struct monitor *pmonitor = NULL;
211 /* message to be displayed after login */
214 /* global authentication context */
215 Authctxt *the_authctxt = NULL;
217 /* Prototypes for various functions defined later in this file. */
218 void destroy_sensitive_data(void);
219 void demote_sensitive_data(void);
221 static void do_ssh1_kex(void);
222 static void do_ssh2_kex(void);
225 * Close all listening sockets
228 close_listen_socks(void)
232 for (i = 0; i < num_listen_socks; i++)
233 close(listen_socks[i]);
234 num_listen_socks = -1;
238 close_startup_pipes(void)
243 for (i = 0; i < options.max_startups; i++)
244 if (startup_pipes[i] != -1)
245 close(startup_pipes[i]);
249 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
250 * the effect is to reread the configuration file (and to regenerate
254 sighup_handler(int sig)
256 int save_errno = errno;
259 signal(SIGHUP, sighup_handler);
264 * Called from the main program after receiving SIGHUP.
265 * Restarts the server.
270 logit("Received SIGHUP; restarting.");
271 close_listen_socks();
272 close_startup_pipes();
273 execv(saved_argv[0], saved_argv);
274 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
280 * Generic signal handler for terminating signals in the master daemon.
283 sigterm_handler(int sig)
285 received_sigterm = sig;
289 * SIGCHLD handler. This is called whenever a child dies. This will then
290 * reap any zombies left by exited children.
293 main_sigchld_handler(int sig)
295 int save_errno = errno;
299 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
300 (pid < 0 && errno == EINTR))
303 signal(SIGCHLD, main_sigchld_handler);
308 * Signal handler for the alarm after the login grace period has expired.
311 grace_alarm_handler(int sig)
313 /* XXX no idea how fix this signal handler */
315 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
316 kill(pmonitor->m_pid, SIGALRM);
318 /* Log error and exit. */
319 fatal("Timeout before authentication for %s", get_remote_ipaddr());
323 * Signal handler for the key regeneration alarm. Note that this
324 * alarm only occurs in the daemon waiting for connections, and it does not
325 * do anything with the private key or random state before forking.
326 * Thus there should be no concurrency control/asynchronous execution
330 generate_ephemeral_server_key(void)
335 verbose("Generating %s%d bit RSA key.",
336 sensitive_data.server_key ? "new " : "", options.server_key_bits);
337 if (sensitive_data.server_key != NULL)
338 key_free(sensitive_data.server_key);
339 sensitive_data.server_key = key_generate(KEY_RSA1,
340 options.server_key_bits);
341 verbose("RSA key generation complete.");
343 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
346 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
353 key_regeneration_alarm(int sig)
355 int save_errno = errno;
357 signal(SIGALRM, SIG_DFL);
363 sshd_exchange_identification(int sock_in, int sock_out)
366 int remote_major, remote_minor;
369 char buf[256]; /* Must not be larger than remote_version. */
370 char remote_version[256]; /* Must be at least as big as buf. */
372 if ((options.protocol & SSH_PROTO_1) &&
373 (options.protocol & SSH_PROTO_2)) {
374 major = PROTOCOL_MAJOR_1;
376 } else if (options.protocol & SSH_PROTO_2) {
377 major = PROTOCOL_MAJOR_2;
378 minor = PROTOCOL_MINOR_2;
380 major = PROTOCOL_MAJOR_1;
381 minor = PROTOCOL_MINOR_1;
383 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
384 server_version_string = xstrdup(buf);
386 /* Send our protocol version identification. */
387 if (atomicio(vwrite, sock_out, server_version_string,
388 strlen(server_version_string))
389 != strlen(server_version_string)) {
390 logit("Could not write ident string to %s", get_remote_ipaddr());
394 /* Read other sides version identification. */
395 memset(buf, 0, sizeof(buf));
396 for (i = 0; i < sizeof(buf) - 1; i++) {
397 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
398 logit("Did not receive identification string from %s",
399 get_remote_ipaddr());
402 if (buf[i] == '\r') {
404 /* Kludge for F-Secure Macintosh < 1.0.2 */
406 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
410 if (buf[i] == '\n') {
415 buf[sizeof(buf) - 1] = 0;
416 client_version_string = xstrdup(buf);
419 * Check that the versions match. In future this might accept
420 * several versions and set appropriate flags to handle them.
422 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
423 &remote_major, &remote_minor, remote_version) != 3) {
424 s = "Protocol mismatch.\n";
425 (void) atomicio(vwrite, sock_out, s, strlen(s));
428 logit("Bad protocol version identification '%.100s' from %s",
429 client_version_string, get_remote_ipaddr());
432 debug("Client protocol version %d.%d; client software version %.100s",
433 remote_major, remote_minor, remote_version);
435 compat_datafellows(remote_version);
437 if (datafellows & SSH_BUG_PROBE) {
438 logit("probed from %s with %s. Don't panic.",
439 get_remote_ipaddr(), client_version_string);
443 if (datafellows & SSH_BUG_SCANNER) {
444 logit("scanned from %s with %s. Don't panic.",
445 get_remote_ipaddr(), client_version_string);
450 switch (remote_major) {
452 if (remote_minor == 99) {
453 if (options.protocol & SSH_PROTO_2)
459 if (!(options.protocol & SSH_PROTO_1)) {
463 if (remote_minor < 3) {
464 packet_disconnect("Your ssh version is too old and "
465 "is no longer supported. Please install a newer version.");
466 } else if (remote_minor == 3) {
467 /* note that this disables agent-forwarding */
472 if (options.protocol & SSH_PROTO_2) {
481 chop(server_version_string);
482 debug("Local version string %.200s", server_version_string);
485 s = "Protocol major versions differ.\n";
486 (void) atomicio(vwrite, sock_out, s, strlen(s));
489 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
491 server_version_string, client_version_string);
496 /* Destroy the host and server keys. They will no longer be needed. */
498 destroy_sensitive_data(void)
502 if (sensitive_data.server_key) {
503 key_free(sensitive_data.server_key);
504 sensitive_data.server_key = NULL;
506 for (i = 0; i < options.num_host_key_files; i++) {
507 if (sensitive_data.host_keys[i]) {
508 key_free(sensitive_data.host_keys[i]);
509 sensitive_data.host_keys[i] = NULL;
512 sensitive_data.ssh1_host_key = NULL;
513 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
516 /* Demote private to public keys for network child */
518 demote_sensitive_data(void)
523 if (sensitive_data.server_key) {
524 tmp = key_demote(sensitive_data.server_key);
525 key_free(sensitive_data.server_key);
526 sensitive_data.server_key = tmp;
529 for (i = 0; i < options.num_host_key_files; i++) {
530 if (sensitive_data.host_keys[i]) {
531 tmp = key_demote(sensitive_data.host_keys[i]);
532 key_free(sensitive_data.host_keys[i]);
533 sensitive_data.host_keys[i] = tmp;
534 if (tmp->type == KEY_RSA1)
535 sensitive_data.ssh1_host_key = tmp;
539 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
543 privsep_preauth_child(void)
550 /* Enable challenge-response authentication for privilege separation */
551 privsep_challenge_enable();
553 for (i = 0; i < 256; i++)
554 rnd[i] = arc4random();
555 RAND_seed(rnd, sizeof(rnd));
557 /* Demote the private keys to public keys. */
558 demote_sensitive_data();
560 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
561 fatal("Privilege separation user %s does not exist",
563 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
566 /* Change our root directory */
567 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
568 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
570 if (chdir("/") == -1)
571 fatal("chdir(\"/\"): %s", strerror(errno));
573 /* Drop our privileges */
574 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
577 /* XXX not ready, too heavy after chroot */
578 do_setusercontext(pw);
580 gidset[0] = pw->pw_gid;
581 if (setgroups(1, gidset) < 0)
582 fatal("setgroups: %.100s", strerror(errno));
583 permanently_set_uid(pw);
588 privsep_preauth(Authctxt *authctxt)
593 /* Set up unprivileged child process to deal with network data */
594 pmonitor = monitor_init();
595 /* Store a pointer to the kex for later rekeying */
596 pmonitor->m_pkex = &xxx_kex;
600 fatal("fork of unprivileged child failed");
601 } else if (pid != 0) {
602 debug2("Network child is on pid %ld", (long)pid);
604 close(pmonitor->m_recvfd);
605 pmonitor->m_pid = pid;
606 monitor_child_preauth(authctxt, pmonitor);
607 close(pmonitor->m_sendfd);
610 monitor_sync(pmonitor);
612 /* Wait for the child's exit status */
613 while (waitpid(pid, &status, 0) < 0)
620 close(pmonitor->m_sendfd);
622 /* Demote the child */
623 if (getuid() == 0 || geteuid() == 0)
624 privsep_preauth_child();
625 setproctitle("%s", "[net]");
631 privsep_postauth(Authctxt *authctxt)
633 #ifdef DISABLE_FD_PASSING
636 if (authctxt->pw->pw_uid == 0 || options.use_login) {
638 /* File descriptor passing is broken or root login */
639 monitor_apply_keystate(pmonitor);
644 /* Authentication complete */
646 if (startup_pipe != -1) {
651 /* New socket pair */
652 monitor_reinit(pmonitor);
654 pmonitor->m_pid = fork();
655 if (pmonitor->m_pid == -1)
656 fatal("fork of unprivileged child failed");
657 else if (pmonitor->m_pid != 0) {
658 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
659 close(pmonitor->m_recvfd);
660 monitor_child_postauth(pmonitor);
666 close(pmonitor->m_sendfd);
668 /* Demote the private keys to public keys. */
669 demote_sensitive_data();
671 /* Drop privileges */
672 do_setusercontext(authctxt->pw);
674 /* It is safe now to apply the key state */
675 monitor_apply_keystate(pmonitor);
679 list_hostkey_types(void)
687 for (i = 0; i < options.num_host_key_files; i++) {
688 Key *key = sensitive_data.host_keys[i];
694 if (buffer_len(&b) > 0)
695 buffer_append(&b, ",", 1);
696 p = key_ssh_name(key);
697 buffer_append(&b, p, strlen(p));
701 buffer_append(&b, "\0", 1);
702 ret = xstrdup(buffer_ptr(&b));
704 debug("list_hostkey_types: %s", ret);
709 get_hostkey_by_type(int type)
713 for (i = 0; i < options.num_host_key_files; i++) {
714 Key *key = sensitive_data.host_keys[i];
715 if (key != NULL && key->type == type)
722 get_hostkey_by_index(int ind)
724 if (ind < 0 || ind >= options.num_host_key_files)
726 return (sensitive_data.host_keys[ind]);
730 get_hostkey_index(Key *key)
734 for (i = 0; i < options.num_host_key_files; i++) {
735 if (key == sensitive_data.host_keys[i])
742 * returns 1 if connection should be dropped, 0 otherwise.
743 * dropping starts at connection #max_startups_begin with a probability
744 * of (max_startups_rate/100). the probability increases linearly until
745 * all connections are dropped for startups > max_startups
748 drop_connection(int startups)
752 if (startups < options.max_startups_begin)
754 if (startups >= options.max_startups)
756 if (options.max_startups_rate == 100)
759 p = 100 - options.max_startups_rate;
760 p *= startups - options.max_startups_begin;
761 p /= (double) (options.max_startups - options.max_startups_begin);
762 p += options.max_startups_rate;
764 r = arc4random() / (double) UINT_MAX;
766 debug("drop_connection: p %g, r %g", p, r);
767 return (r < p) ? 1 : 0;
773 fprintf(stderr, "%s, %s\n",
774 SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
776 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
777 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
783 send_rexec_state(int fd, Buffer *conf)
787 debug3("%s: entering fd = %d config len %d", __func__, fd,
791 * Protocol from reexec master to child:
792 * string configuration
793 * u_int ephemeral_key_follows
794 * bignum e (only if ephemeral_key_follows == 1)
802 buffer_put_cstring(&m, buffer_ptr(conf));
804 if (sensitive_data.server_key != NULL &&
805 sensitive_data.server_key->type == KEY_RSA1) {
806 buffer_put_int(&m, 1);
807 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
808 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
809 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
810 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
811 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
812 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
814 buffer_put_int(&m, 0);
816 if (ssh_msg_send(fd, 0, &m) == -1)
817 fatal("%s: ssh_msg_send failed", __func__);
821 debug3("%s: done", __func__);
825 recv_rexec_state(int fd, Buffer *conf)
831 debug3("%s: entering fd = %d", __func__, fd);
835 if (ssh_msg_recv(fd, &m) == -1)
836 fatal("%s: ssh_msg_recv failed", __func__);
837 if (buffer_get_char(&m) != 0)
838 fatal("%s: rexec version mismatch", __func__);
840 cp = buffer_get_string(&m, &len);
842 buffer_append(conf, cp, len + 1);
845 if (buffer_get_int(&m)) {
846 if (sensitive_data.server_key != NULL)
847 key_free(sensitive_data.server_key);
848 sensitive_data.server_key = key_new_private(KEY_RSA1);
849 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
850 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
851 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
852 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
853 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
854 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
855 rsa_generate_additional_parameters(
856 sensitive_data.server_key->rsa);
860 debug3("%s: done", __func__);
864 * Main program for the daemon.
867 main(int ac, char **av)
871 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
875 struct sockaddr_storage from;
876 const char *remote_ip;
880 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
882 int listen_sock, maxfd;
883 int startup_p[2], config_s[2];
887 int ret, key_used = 0;
890 #ifdef HAVE_SECUREWARE
891 (void)set_auth_parameters(ac, av);
893 __progname = ssh_get_progname(av[0]);
896 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
899 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
900 for (i = 0; i < ac; i++)
901 saved_argv[i] = xstrdup(av[i]);
902 saved_argv[i] = NULL;
904 #ifndef HAVE_SETPROCTITLE
905 /* Prepare for later setproctitle emulation */
906 compat_init_setproctitle(ac, av);
910 if (geteuid() == 0 && setgroups(0, NULL) == -1)
911 debug("setgroups(): %.200s", strerror(errno));
913 /* Initialize configuration options to their default values. */
914 initialize_server_options(&options);
916 /* Parse command-line arguments. */
917 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
926 config_file_name = optarg;
929 if (debug_flag == 0) {
931 options.log_level = SYSLOG_LEVEL_DEBUG1;
932 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
955 options.log_level = SYSLOG_LEVEL_QUIET;
958 options.server_key_bits = atoi(optarg);
961 options.ports_from_cmdline = 1;
962 if (options.num_ports >= MAX_PORTS) {
963 fprintf(stderr, "too many ports.\n");
966 options.ports[options.num_ports++] = a2port(optarg);
967 if (options.ports[options.num_ports-1] == 0) {
968 fprintf(stderr, "Bad port number.\n");
973 if ((options.login_grace_time = convtime(optarg)) == -1) {
974 fprintf(stderr, "Invalid login grace time.\n");
979 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
980 fprintf(stderr, "Invalid key regeneration interval.\n");
985 if (options.num_host_key_files >= MAX_HOSTKEYS) {
986 fprintf(stderr, "too many host keys.\n");
989 options.host_key_files[options.num_host_key_files++] = optarg;
995 utmp_len = atoi(optarg);
996 if (utmp_len > MAXHOSTNAMELEN) {
997 fprintf(stderr, "Invalid utmp length.\n");
1002 line = xstrdup(optarg);
1003 if (process_server_config_line(&options, line,
1004 "command-line", 0) != 0)
1014 if (rexeced_flag || inetd_flag)
1016 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1017 fatal("sshd re-exec requires execution with an absolute path");
1019 closefrom(STDERR_FILENO + 3);
1021 SSLeay_add_all_algorithms();
1022 channel_set_af(IPv4or6);
1025 * Force logging to stderr until we have loaded the private host
1026 * key (unless started from inetd)
1028 log_init(__progname,
1029 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1030 SYSLOG_LEVEL_INFO : options.log_level,
1031 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1032 SYSLOG_FACILITY_AUTH : options.log_facility,
1033 log_stderr || !inetd_flag);
1037 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1038 * root's environment
1040 unsetenv("KRB5CCNAME");
1043 /* Cray can define user privs drop all privs now!
1044 * Not needed on PRIV_SU systems!
1051 sensitive_data.server_key = NULL;
1052 sensitive_data.ssh1_host_key = NULL;
1053 sensitive_data.have_ssh1_key = 0;
1054 sensitive_data.have_ssh2_key = 0;
1056 /* Fetch our configuration */
1059 recv_rexec_state(STDERR_FILENO + 2, &cfg);
1061 load_server_config(config_file_name, &cfg);
1063 parse_server_config(&options,
1064 rexeced_flag ? "rexec" : config_file_name, &cfg);
1069 /* Fill in default values for those options not explicitly set. */
1070 fill_default_server_options(&options);
1072 /* Check that there are no remaining arguments. */
1074 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1078 debug("sshd version %.100s", SSH_VERSION);
1080 /* load private host keys */
1081 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1083 for (i = 0; i < options.num_host_key_files; i++)
1084 sensitive_data.host_keys[i] = NULL;
1086 for (i = 0; i < options.num_host_key_files; i++) {
1087 key = key_load_private(options.host_key_files[i], "", NULL);
1088 sensitive_data.host_keys[i] = key;
1090 error("Could not load host key: %s",
1091 options.host_key_files[i]);
1092 sensitive_data.host_keys[i] = NULL;
1095 switch (key->type) {
1097 sensitive_data.ssh1_host_key = key;
1098 sensitive_data.have_ssh1_key = 1;
1102 sensitive_data.have_ssh2_key = 1;
1105 debug("private host key: #%d type %d %s", i, key->type,
1108 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1109 logit("Disabling protocol version 1. Could not load host key");
1110 options.protocol &= ~SSH_PROTO_1;
1112 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1113 logit("Disabling protocol version 2. Could not load host key");
1114 options.protocol &= ~SSH_PROTO_2;
1116 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1117 logit("sshd: no hostkeys available -- exiting.");
1121 /* Check certain values for sanity. */
1122 if (options.protocol & SSH_PROTO_1) {
1123 if (options.server_key_bits < 512 ||
1124 options.server_key_bits > 32768) {
1125 fprintf(stderr, "Bad server key size.\n");
1129 * Check that server and host key lengths differ sufficiently. This
1130 * is necessary to make double encryption work with rsaref. Oh, I
1131 * hate software patents. I dont know if this can go? Niels
1133 if (options.server_key_bits >
1134 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1135 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1136 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1137 SSH_KEY_BITS_RESERVED) {
1138 options.server_key_bits =
1139 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1140 SSH_KEY_BITS_RESERVED;
1141 debug("Forcing server key to %d bits to make it differ from host key.",
1142 options.server_key_bits);
1150 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1151 fatal("Privilege separation user %s does not exist",
1153 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1154 (S_ISDIR(st.st_mode) == 0))
1155 fatal("Missing privilege separation directory: %s",
1156 _PATH_PRIVSEP_CHROOT_DIR);
1159 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1160 (st.st_uid != getuid () ||
1161 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1163 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1165 fatal("%s must be owned by root and not group or "
1166 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1169 /* Configuration looks good, so exit if in test mode. */
1174 * Clear out any supplemental groups we may have inherited. This
1175 * prevents inadvertent creation of files with bad modes (in the
1176 * portable version at least, it's certainly possible for PAM
1177 * to create a file, and we can't control the code in every
1178 * module which might be used).
1180 if (setgroups(0, NULL) < 0)
1181 debug("setgroups() failed: %.200s", strerror(errno));
1184 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1185 for (i = 0; i < rexec_argc; i++) {
1186 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1187 rexec_argv[i] = saved_argv[i];
1189 rexec_argv[rexec_argc] = "-R";
1190 rexec_argv[rexec_argc + 1] = NULL;
1193 /* Initialize the log (it is reinitialized below in case we forked). */
1194 if (debug_flag && !inetd_flag)
1196 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1199 * If not in debugging mode, and not started from inetd, disconnect
1200 * from the controlling terminal, and fork. The original process
1203 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1206 #endif /* TIOCNOTTY */
1207 if (daemon(0, 0) < 0)
1208 fatal("daemon() failed: %.200s", strerror(errno));
1210 /* Disconnect from the controlling tty. */
1212 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1214 (void) ioctl(fd, TIOCNOTTY, NULL);
1217 #endif /* TIOCNOTTY */
1219 /* Reinitialize the log (because of the fork above). */
1220 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1222 /* Initialize the random number generator. */
1225 /* Chdir to the root directory so that the current disk can be
1226 unmounted if desired. */
1229 /* ignore SIGPIPE */
1230 signal(SIGPIPE, SIG_IGN);
1232 /* Start listening for a socket, unless started from inetd. */
1238 close(STDERR_FILENO + 2);
1239 sock_in = sock_out = dup(STDIN_FILENO);
1241 startup_pipe = dup(STDERR_FILENO + 1);
1242 close(STDERR_FILENO + 1);
1245 sock_in = dup(STDIN_FILENO);
1246 sock_out = dup(STDOUT_FILENO);
1249 * We intentionally do not close the descriptors 0, 1, and 2
1250 * as our code for setting the descriptors won't work if
1251 * ttyfd happens to be one of those.
1253 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1254 dup2(fd, STDIN_FILENO);
1255 dup2(fd, STDOUT_FILENO);
1256 if (fd > STDOUT_FILENO)
1259 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1260 if ((options.protocol & SSH_PROTO_1) &&
1261 sensitive_data.server_key == NULL)
1262 generate_ephemeral_server_key();
1264 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1265 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1267 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1268 fatal("Too many listen sockets. "
1269 "Enlarge MAX_LISTEN_SOCKS");
1270 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1271 ntop, sizeof(ntop), strport, sizeof(strport),
1272 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1273 error("getnameinfo failed");
1276 /* Create socket for listening. */
1277 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1279 if (listen_sock < 0) {
1280 /* kernel may not support ipv6 */
1281 verbose("socket: %.100s", strerror(errno));
1284 if (set_nonblock(listen_sock) == -1) {
1289 * Set socket options.
1290 * Allow local port reuse in TIME_WAIT.
1292 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1293 &on, sizeof(on)) == -1)
1294 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1296 debug("Bind to port %s on %s.", strport, ntop);
1298 /* Bind the socket to the desired port. */
1299 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1301 error("Bind to port %s on %s failed: %.200s.",
1302 strport, ntop, strerror(errno));
1306 listen_socks[num_listen_socks] = listen_sock;
1309 /* Start listening on the port. */
1310 logit("Server listening on %s port %s.", ntop, strport);
1311 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1312 fatal("listen: %.100s", strerror(errno));
1315 freeaddrinfo(options.listen_addrs);
1317 if (!num_listen_socks)
1318 fatal("Cannot bind any address.");
1320 if (options.protocol & SSH_PROTO_1)
1321 generate_ephemeral_server_key();
1324 * Arrange to restart on SIGHUP. The handler needs
1327 signal(SIGHUP, sighup_handler);
1329 signal(SIGTERM, sigterm_handler);
1330 signal(SIGQUIT, sigterm_handler);
1332 /* Arrange SIGCHLD to be caught. */
1333 signal(SIGCHLD, main_sigchld_handler);
1335 /* Write out the pid file after the sigterm handler is setup */
1338 * Record our pid in /var/run/sshd.pid to make it
1339 * easier to kill the correct sshd. We don't want to
1340 * do this before the bind above because the bind will
1341 * fail if there already is a daemon, and this will
1342 * overwrite any old pid in the file.
1344 f = fopen(options.pid_file, "wb");
1346 error("Couldn't create pid file \"%s\": %s",
1347 options.pid_file, strerror(errno));
1349 fprintf(f, "%ld\n", (long) getpid());
1354 /* setup fd set for listen */
1357 for (i = 0; i < num_listen_socks; i++)
1358 if (listen_socks[i] > maxfd)
1359 maxfd = listen_socks[i];
1360 /* pipes connected to unauthenticated childs */
1361 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1362 for (i = 0; i < options.max_startups; i++)
1363 startup_pipes[i] = -1;
1366 * Stay listening for connections until the system crashes or
1367 * the daemon is killed with a signal.
1370 if (received_sighup)
1374 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1375 fdset = (fd_set *)xmalloc(fdsetsz);
1376 memset(fdset, 0, fdsetsz);
1378 for (i = 0; i < num_listen_socks; i++)
1379 FD_SET(listen_socks[i], fdset);
1380 for (i = 0; i < options.max_startups; i++)
1381 if (startup_pipes[i] != -1)
1382 FD_SET(startup_pipes[i], fdset);
1384 /* Wait in select until there is a connection. */
1385 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1386 if (ret < 0 && errno != EINTR)
1387 error("select: %.100s", strerror(errno));
1388 if (received_sigterm) {
1389 logit("Received signal %d; terminating.",
1390 (int) received_sigterm);
1391 close_listen_socks();
1392 unlink(options.pid_file);
1395 if (key_used && key_do_regen) {
1396 generate_ephemeral_server_key();
1403 for (i = 0; i < options.max_startups; i++)
1404 if (startup_pipes[i] != -1 &&
1405 FD_ISSET(startup_pipes[i], fdset)) {
1407 * the read end of the pipe is ready
1408 * if the child has closed the pipe
1409 * after successful authentication
1410 * or if the child has died
1412 close(startup_pipes[i]);
1413 startup_pipes[i] = -1;
1416 for (i = 0; i < num_listen_socks; i++) {
1417 if (!FD_ISSET(listen_socks[i], fdset))
1419 fromlen = sizeof(from);
1420 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1423 if (errno != EINTR && errno != EWOULDBLOCK)
1424 error("accept: %.100s", strerror(errno));
1427 if (unset_nonblock(newsock) == -1) {
1431 if (drop_connection(startups) == 1) {
1432 debug("drop connection #%d", startups);
1436 if (pipe(startup_p) == -1) {
1441 if (rexec_flag && socketpair(AF_UNIX,
1442 SOCK_STREAM, 0, config_s) == -1) {
1443 error("reexec socketpair: %s",
1446 close(startup_p[0]);
1447 close(startup_p[1]);
1451 for (j = 0; j < options.max_startups; j++)
1452 if (startup_pipes[j] == -1) {
1453 startup_pipes[j] = startup_p[0];
1454 if (maxfd < startup_p[0])
1455 maxfd = startup_p[0];
1461 * Got connection. Fork a child to handle it, unless
1462 * we are in debugging mode.
1466 * In debugging mode. Close the listening
1467 * socket, and start processing the
1468 * connection without forking.
1470 debug("Server will not fork when running in debugging mode.");
1471 close_listen_socks();
1474 close(startup_p[0]);
1475 close(startup_p[1]);
1479 send_rexec_state(config_s[0],
1486 * Normal production daemon. Fork, and have
1487 * the child process the connection. The
1488 * parent continues listening.
1490 if ((pid = fork()) == 0) {
1492 * Child. Close the listening and max_startup
1493 * sockets. Start using the accepted socket.
1494 * Reinitialize logging (since our pid has
1495 * changed). We break out of the loop to handle
1498 startup_pipe = startup_p[1];
1499 close_startup_pipes();
1500 close_listen_socks();
1503 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1508 /* Parent. Stay in the loop. */
1510 error("fork: %.100s", strerror(errno));
1512 debug("Forked child %ld.", (long)pid);
1514 close(startup_p[1]);
1517 send_rexec_state(config_s[0], &cfg);
1522 /* Mark that the key has been used (it was "given" to the child). */
1523 if ((options.protocol & SSH_PROTO_1) &&
1525 /* Schedule server key regeneration alarm. */
1526 signal(SIGALRM, key_regeneration_alarm);
1527 alarm(options.key_regeneration_time);
1533 /* Close the new socket (the child is now taking care of it). */
1536 /* child process check (or debug mode) */
1537 if (num_listen_socks < 0)
1542 /* This is the child processing a new connection. */
1543 setproctitle("%s", "[accepted]");
1548 debug("rexec newsock %d pipe %d sock %d", newsock,
1549 startup_pipe, config_s[0]);
1550 dup2(newsock, STDIN_FILENO);
1551 dup2(STDIN_FILENO, STDOUT_FILENO);
1552 if (startup_pipe == -1)
1553 close(STDERR_FILENO + 1);
1555 dup2(startup_pipe, STDERR_FILENO + 1);
1557 dup2(config_s[1], STDERR_FILENO + 2);
1559 execv(rexec_argv[0], rexec_argv);
1561 /* Reexec has failed, fall back and continue */
1562 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1563 recv_rexec_state(STDERR_FILENO + 2, NULL);
1564 log_init(__progname, options.log_level,
1565 options.log_facility, log_stderr);
1569 close(STDERR_FILENO + 1);
1570 close(STDERR_FILENO + 2);
1571 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1572 dup2(fd, STDIN_FILENO);
1573 dup2(fd, STDOUT_FILENO);
1574 if (fd > STDERR_FILENO)
1580 * Create a new session and process group since the 4.4BSD
1581 * setlogin() affects the entire process group. We don't
1582 * want the child to be able to affect the parent.
1584 #if !defined(SSHD_ACQUIRES_CTTY)
1586 * If setsid is called, on some platforms sshd will later acquire a
1587 * controlling terminal which will result in "could not set
1588 * controlling tty" errors.
1590 if (!debug_flag && !inetd_flag && setsid() < 0)
1591 error("setsid: %.100s", strerror(errno));
1595 * Disable the key regeneration alarm. We will not regenerate the
1596 * key since we are no longer in a position to give it to anyone. We
1597 * will not restart on SIGHUP since it no longer makes sense.
1600 signal(SIGALRM, SIG_DFL);
1601 signal(SIGHUP, SIG_DFL);
1602 signal(SIGTERM, SIG_DFL);
1603 signal(SIGQUIT, SIG_DFL);
1604 signal(SIGCHLD, SIG_DFL);
1605 signal(SIGINT, SIG_DFL);
1607 /* Set SO_KEEPALIVE if requested. */
1608 if (options.tcp_keep_alive &&
1609 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1611 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1614 * Register our connection. This turns encryption off because we do
1617 packet_set_connection(sock_in, sock_out);
1619 remote_port = get_remote_port();
1620 remote_ip = get_remote_ipaddr();
1623 /* Check whether logins are denied from this host. */
1624 if (packet_connection_is_on_socket()) {
1625 struct request_info req;
1627 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1630 if (!hosts_access(&req)) {
1631 debug("Connection refused by tcp wrapper");
1634 fatal("libwrap refuse returns");
1637 #endif /* LIBWRAP */
1639 /* Log the connection. */
1640 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1643 * We don\'t want to listen forever unless the other side
1644 * successfully authenticates itself. So we set up an alarm which is
1645 * cleared after successful authentication. A limit of zero
1646 * indicates no limit. Note that we don\'t set the alarm in debugging
1647 * mode; it is just annoying to have the server exit just when you
1648 * are about to discover the bug.
1650 signal(SIGALRM, grace_alarm_handler);
1652 alarm(options.login_grace_time);
1654 sshd_exchange_identification(sock_in, sock_out);
1656 packet_set_nonblocking();
1658 /* prepare buffers to collect authentication messages */
1659 buffer_init(&loginmsg);
1661 /* allocate authentication context */
1662 authctxt = xmalloc(sizeof(*authctxt));
1663 memset(authctxt, 0, sizeof(*authctxt));
1665 /* XXX global for cleanup, access from other modules */
1666 the_authctxt = authctxt;
1669 if (privsep_preauth(authctxt) == 1)
1672 /* perform the key exchange */
1673 /* authenticate user and start session */
1676 do_authentication2(authctxt);
1679 do_authentication(authctxt);
1682 * If we use privilege separation, the unprivileged child transfers
1683 * the current keystate and exits
1686 mm_send_keystate(pmonitor);
1692 * In privilege separation, we fork another child and prepare
1693 * file descriptor passing.
1696 privsep_postauth(authctxt);
1697 /* the monitor process [priv] will not return */
1699 destroy_sensitive_data();
1702 /* Start session. */
1703 do_authenticated(authctxt);
1705 /* The connection has been terminated. */
1706 verbose("Closing connection to %.100s", remote_ip);
1709 if (options.use_pam)
1711 #endif /* USE_PAM */
1722 * Decrypt session_key_int using our private server key and private host key
1723 * (key with larger modulus first).
1726 ssh1_session_key(BIGNUM *session_key_int)
1730 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1731 /* Server key has bigger modulus. */
1732 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1733 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1734 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1735 get_remote_ipaddr(),
1736 BN_num_bits(sensitive_data.server_key->rsa->n),
1737 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1738 SSH_KEY_BITS_RESERVED);
1740 if (rsa_private_decrypt(session_key_int, session_key_int,
1741 sensitive_data.server_key->rsa) <= 0)
1743 if (rsa_private_decrypt(session_key_int, session_key_int,
1744 sensitive_data.ssh1_host_key->rsa) <= 0)
1747 /* Host key has bigger modulus (or they are equal). */
1748 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1749 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1750 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1751 get_remote_ipaddr(),
1752 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1753 BN_num_bits(sensitive_data.server_key->rsa->n),
1754 SSH_KEY_BITS_RESERVED);
1756 if (rsa_private_decrypt(session_key_int, session_key_int,
1757 sensitive_data.ssh1_host_key->rsa) < 0)
1759 if (rsa_private_decrypt(session_key_int, session_key_int,
1760 sensitive_data.server_key->rsa) < 0)
1773 BIGNUM *session_key_int;
1774 u_char session_key[SSH_SESSION_KEY_LENGTH];
1776 u_int cipher_type, auth_mask, protocol_flags;
1780 * Generate check bytes that the client must send back in the user
1781 * packet in order for it to be accepted; this is used to defy ip
1782 * spoofing attacks. Note that this only works against somebody
1783 * doing IP spoofing from a remote machine; any machine on the local
1784 * network can still see outgoing packets and catch the random
1785 * cookie. This only affects rhosts authentication, and this is one
1786 * of the reasons why it is inherently insecure.
1788 for (i = 0; i < 8; i++) {
1791 cookie[i] = rnd & 0xff;
1796 * Send our public key. We include in the packet 64 bits of random
1797 * data that must be matched in the reply in order to prevent IP
1800 packet_start(SSH_SMSG_PUBLIC_KEY);
1801 for (i = 0; i < 8; i++)
1802 packet_put_char(cookie[i]);
1804 /* Store our public server RSA key. */
1805 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1806 packet_put_bignum(sensitive_data.server_key->rsa->e);
1807 packet_put_bignum(sensitive_data.server_key->rsa->n);
1809 /* Store our public host RSA key. */
1810 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1811 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1812 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1814 /* Put protocol flags. */
1815 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1817 /* Declare which ciphers we support. */
1818 packet_put_int(cipher_mask_ssh1(0));
1820 /* Declare supported authentication types. */
1822 if (options.rhosts_rsa_authentication)
1823 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1824 if (options.rsa_authentication)
1825 auth_mask |= 1 << SSH_AUTH_RSA;
1826 if (options.challenge_response_authentication == 1)
1827 auth_mask |= 1 << SSH_AUTH_TIS;
1828 if (options.password_authentication)
1829 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1830 packet_put_int(auth_mask);
1832 /* Send the packet and wait for it to be sent. */
1834 packet_write_wait();
1836 debug("Sent %d bit server key and %d bit host key.",
1837 BN_num_bits(sensitive_data.server_key->rsa->n),
1838 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1840 /* Read clients reply (cipher type and session key). */
1841 packet_read_expect(SSH_CMSG_SESSION_KEY);
1843 /* Get cipher type and check whether we accept this. */
1844 cipher_type = packet_get_char();
1846 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1847 packet_disconnect("Warning: client selects unsupported cipher.");
1849 /* Get check bytes from the packet. These must match those we
1850 sent earlier with the public key packet. */
1851 for (i = 0; i < 8; i++)
1852 if (cookie[i] != packet_get_char())
1853 packet_disconnect("IP Spoofing check bytes do not match.");
1855 debug("Encryption type: %.200s", cipher_name(cipher_type));
1857 /* Get the encrypted integer. */
1858 if ((session_key_int = BN_new()) == NULL)
1859 fatal("do_ssh1_kex: BN_new failed");
1860 packet_get_bignum(session_key_int);
1862 protocol_flags = packet_get_int();
1863 packet_set_protocol_flags(protocol_flags);
1866 /* Decrypt session_key_int using host/server keys */
1867 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1870 * Extract session key from the decrypted integer. The key is in the
1871 * least significant 256 bits of the integer; the first byte of the
1872 * key is in the highest bits.
1875 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1876 len = BN_num_bytes(session_key_int);
1877 if (len < 0 || len > sizeof(session_key)) {
1878 error("do_connection: bad session key len from %s: "
1879 "session_key_int %d > sizeof(session_key) %lu",
1880 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1883 memset(session_key, 0, sizeof(session_key));
1884 BN_bn2bin(session_key_int,
1885 session_key + sizeof(session_key) - len);
1887 derive_ssh1_session_id(
1888 sensitive_data.ssh1_host_key->rsa->n,
1889 sensitive_data.server_key->rsa->n,
1890 cookie, session_id);
1892 * Xor the first 16 bytes of the session key with the
1895 for (i = 0; i < 16; i++)
1896 session_key[i] ^= session_id[i];
1900 int bytes = BN_num_bytes(session_key_int);
1901 u_char *buf = xmalloc(bytes);
1904 logit("do_connection: generating a fake encryption key");
1905 BN_bn2bin(session_key_int, buf);
1907 MD5_Update(&md, buf, bytes);
1908 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1909 MD5_Final(session_key, &md);
1911 MD5_Update(&md, session_key, 16);
1912 MD5_Update(&md, buf, bytes);
1913 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1914 MD5_Final(session_key + 16, &md);
1915 memset(buf, 0, bytes);
1917 for (i = 0; i < 16; i++)
1918 session_id[i] = session_key[i] ^ session_key[i + 16];
1920 /* Destroy the private and public keys. No longer. */
1921 destroy_sensitive_data();
1924 mm_ssh1_session_id(session_id);
1926 /* Destroy the decrypted integer. It is no longer needed. */
1927 BN_clear_free(session_key_int);
1929 /* Set the session key. From this on all communications will be encrypted. */
1930 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1932 /* Destroy our copy of the session key. It is no longer needed. */
1933 memset(session_key, 0, sizeof(session_key));
1935 debug("Received session key; encryption turned on.");
1937 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1938 packet_start(SSH_SMSG_SUCCESS);
1940 packet_write_wait();
1944 * SSH2 key exchange: diffie-hellman-group1-sha1
1951 if (options.ciphers != NULL) {
1952 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1953 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1955 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1956 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1957 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1958 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1960 if (options.macs != NULL) {
1961 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1962 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1964 if (!options.compression) {
1965 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1966 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1968 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1970 /* start key exchange */
1971 kex = kex_setup(myproposal);
1972 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1973 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1974 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1976 kex->client_version_string=client_version_string;
1977 kex->server_version_string=server_version_string;
1978 kex->load_host_key=&get_hostkey_by_type;
1979 kex->host_key_index=&get_hostkey_index;
1983 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1985 session_id2 = kex->session_id;
1986 session_id2_len = kex->session_id_len;
1989 /* send 1st encrypted/maced/compressed message */
1990 packet_start(SSH2_MSG_IGNORE);
1991 packet_put_cstring("markus");
1993 packet_write_wait();
1998 /* server specific fatal cleanup */
2003 do_cleanup(the_authctxt);