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 1.297 2004/06/26 20:07:16 avsm 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 #ifdef HAVE___PROGNAME
107 extern char *__progname;
112 /* Server configuration options. */
113 ServerOptions options;
115 /* Name of the server configuration file. */
116 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
119 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
120 * Default value is AF_UNSPEC means both IPv4 and IPv6.
122 int IPv4or6 = AF_UNSPEC;
125 * Debug mode flag. This can be set on the command line. If debug
126 * mode is enabled, extra debugging output will be sent to the system
127 * log, the daemon will not go to background, and will exit after processing
128 * the first connection.
132 /* Flag indicating that the daemon should only test the configuration and keys. */
135 /* Flag indicating that the daemon is being started from inetd. */
138 /* Flag indicating that sshd should not detach and become a daemon. */
139 int no_daemon_flag = 0;
141 /* debug goes to stderr unless inetd_flag is set */
144 /* Saved arguments to main(). */
149 int rexeced_flag = 0;
155 * The sockets that the server is listening; this is used in the SIGHUP
158 #define MAX_LISTEN_SOCKS 16
159 int listen_socks[MAX_LISTEN_SOCKS];
160 int num_listen_socks = 0;
163 * the client's version string, passed by sshd2 in compat mode. if != NULL,
164 * sshd will skip the version-number exchange
166 char *client_version_string = NULL;
167 char *server_version_string = NULL;
169 /* for rekeying XXX fixme */
173 * Any really sensitive data in the application is contained in this
174 * structure. The idea is that this structure could be locked into memory so
175 * that the pages do not get written into swap. However, there are some
176 * problems. The private key contains BIGNUMs, and we do not (in principle)
177 * have access to the internals of them, and locking just the structure is
178 * not very useful. Currently, memory locking is not implemented.
181 Key *server_key; /* ephemeral server key */
182 Key *ssh1_host_key; /* ssh1 host key */
183 Key **host_keys; /* all private host keys */
186 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
190 * Flag indicating whether the RSA server key needs to be regenerated.
191 * Is set in the SIGALRM handler and cleared when the key is regenerated.
193 static volatile sig_atomic_t key_do_regen = 0;
195 /* This is set to true when a signal is received. */
196 static volatile sig_atomic_t received_sighup = 0;
197 static volatile sig_atomic_t received_sigterm = 0;
199 /* session identifier, used by RSA-auth */
200 u_char session_id[16];
203 u_char *session_id2 = NULL;
204 u_int session_id2_len = 0;
206 /* record remote hostname or ip */
207 u_int utmp_len = MAXHOSTNAMELEN;
209 /* options.max_startup sized array of fd ints */
210 int *startup_pipes = NULL;
211 int startup_pipe; /* in child */
213 /* variables used for privilege separation */
215 struct monitor *pmonitor = NULL;
217 /* message to be displayed after login */
220 /* global authentication context */
221 Authctxt *the_authctxt = NULL;
223 /* Prototypes for various functions defined later in this file. */
224 void destroy_sensitive_data(void);
225 void demote_sensitive_data(void);
227 static void do_ssh1_kex(void);
228 static void do_ssh2_kex(void);
231 * Close all listening sockets
234 close_listen_socks(void)
238 for (i = 0; i < num_listen_socks; i++)
239 close(listen_socks[i]);
240 num_listen_socks = -1;
244 close_startup_pipes(void)
249 for (i = 0; i < options.max_startups; i++)
250 if (startup_pipes[i] != -1)
251 close(startup_pipes[i]);
255 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
256 * the effect is to reread the configuration file (and to regenerate
260 sighup_handler(int sig)
262 int save_errno = errno;
265 signal(SIGHUP, sighup_handler);
270 * Called from the main program after receiving SIGHUP.
271 * Restarts the server.
276 logit("Received SIGHUP; restarting.");
277 close_listen_socks();
278 close_startup_pipes();
279 execv(saved_argv[0], saved_argv);
280 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
286 * Generic signal handler for terminating signals in the master daemon.
289 sigterm_handler(int sig)
291 received_sigterm = sig;
295 * SIGCHLD handler. This is called whenever a child dies. This will then
296 * reap any zombies left by exited children.
299 main_sigchld_handler(int sig)
301 int save_errno = errno;
305 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
306 (pid < 0 && errno == EINTR))
309 signal(SIGCHLD, main_sigchld_handler);
314 * Signal handler for the alarm after the login grace period has expired.
317 grace_alarm_handler(int sig)
319 /* XXX no idea how fix this signal handler */
321 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
322 kill(pmonitor->m_pid, SIGALRM);
324 /* Log error and exit. */
325 fatal("Timeout before authentication for %s", get_remote_ipaddr());
329 * Signal handler for the key regeneration alarm. Note that this
330 * alarm only occurs in the daemon waiting for connections, and it does not
331 * do anything with the private key or random state before forking.
332 * Thus there should be no concurrency control/asynchronous execution
336 generate_ephemeral_server_key(void)
341 verbose("Generating %s%d bit RSA key.",
342 sensitive_data.server_key ? "new " : "", options.server_key_bits);
343 if (sensitive_data.server_key != NULL)
344 key_free(sensitive_data.server_key);
345 sensitive_data.server_key = key_generate(KEY_RSA1,
346 options.server_key_bits);
347 verbose("RSA key generation complete.");
349 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
352 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
359 key_regeneration_alarm(int sig)
361 int save_errno = errno;
363 signal(SIGALRM, SIG_DFL);
369 sshd_exchange_identification(int sock_in, int sock_out)
372 int remote_major, remote_minor;
375 char buf[256]; /* Must not be larger than remote_version. */
376 char remote_version[256]; /* Must be at least as big as buf. */
378 if ((options.protocol & SSH_PROTO_1) &&
379 (options.protocol & SSH_PROTO_2)) {
380 major = PROTOCOL_MAJOR_1;
382 } else if (options.protocol & SSH_PROTO_2) {
383 major = PROTOCOL_MAJOR_2;
384 minor = PROTOCOL_MINOR_2;
386 major = PROTOCOL_MAJOR_1;
387 minor = PROTOCOL_MINOR_1;
389 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
390 server_version_string = xstrdup(buf);
392 /* Send our protocol version identification. */
393 if (atomicio(vwrite, sock_out, server_version_string,
394 strlen(server_version_string))
395 != strlen(server_version_string)) {
396 logit("Could not write ident string to %s", get_remote_ipaddr());
400 /* Read other sides version identification. */
401 memset(buf, 0, sizeof(buf));
402 for (i = 0; i < sizeof(buf) - 1; i++) {
403 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
404 logit("Did not receive identification string from %s",
405 get_remote_ipaddr());
408 if (buf[i] == '\r') {
410 /* Kludge for F-Secure Macintosh < 1.0.2 */
412 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
416 if (buf[i] == '\n') {
421 buf[sizeof(buf) - 1] = 0;
422 client_version_string = xstrdup(buf);
425 * Check that the versions match. In future this might accept
426 * several versions and set appropriate flags to handle them.
428 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
429 &remote_major, &remote_minor, remote_version) != 3) {
430 s = "Protocol mismatch.\n";
431 (void) atomicio(vwrite, sock_out, s, strlen(s));
434 logit("Bad protocol version identification '%.100s' from %s",
435 client_version_string, get_remote_ipaddr());
438 debug("Client protocol version %d.%d; client software version %.100s",
439 remote_major, remote_minor, remote_version);
441 compat_datafellows(remote_version);
443 if (datafellows & SSH_BUG_PROBE) {
444 logit("probed from %s with %s. Don't panic.",
445 get_remote_ipaddr(), client_version_string);
449 if (datafellows & SSH_BUG_SCANNER) {
450 logit("scanned from %s with %s. Don't panic.",
451 get_remote_ipaddr(), client_version_string);
456 switch (remote_major) {
458 if (remote_minor == 99) {
459 if (options.protocol & SSH_PROTO_2)
465 if (!(options.protocol & SSH_PROTO_1)) {
469 if (remote_minor < 3) {
470 packet_disconnect("Your ssh version is too old and "
471 "is no longer supported. Please install a newer version.");
472 } else if (remote_minor == 3) {
473 /* note that this disables agent-forwarding */
478 if (options.protocol & SSH_PROTO_2) {
487 chop(server_version_string);
488 debug("Local version string %.200s", server_version_string);
491 s = "Protocol major versions differ.\n";
492 (void) atomicio(vwrite, sock_out, s, strlen(s));
495 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
497 server_version_string, client_version_string);
502 /* Destroy the host and server keys. They will no longer be needed. */
504 destroy_sensitive_data(void)
508 if (sensitive_data.server_key) {
509 key_free(sensitive_data.server_key);
510 sensitive_data.server_key = NULL;
512 for (i = 0; i < options.num_host_key_files; i++) {
513 if (sensitive_data.host_keys[i]) {
514 key_free(sensitive_data.host_keys[i]);
515 sensitive_data.host_keys[i] = NULL;
518 sensitive_data.ssh1_host_key = NULL;
519 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
522 /* Demote private to public keys for network child */
524 demote_sensitive_data(void)
529 if (sensitive_data.server_key) {
530 tmp = key_demote(sensitive_data.server_key);
531 key_free(sensitive_data.server_key);
532 sensitive_data.server_key = tmp;
535 for (i = 0; i < options.num_host_key_files; i++) {
536 if (sensitive_data.host_keys[i]) {
537 tmp = key_demote(sensitive_data.host_keys[i]);
538 key_free(sensitive_data.host_keys[i]);
539 sensitive_data.host_keys[i] = tmp;
540 if (tmp->type == KEY_RSA1)
541 sensitive_data.ssh1_host_key = tmp;
545 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
549 privsep_preauth_child(void)
556 /* Enable challenge-response authentication for privilege separation */
557 privsep_challenge_enable();
559 for (i = 0; i < 256; i++)
560 rnd[i] = arc4random();
561 RAND_seed(rnd, sizeof(rnd));
563 /* Demote the private keys to public keys. */
564 demote_sensitive_data();
566 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
567 fatal("Privilege separation user %s does not exist",
569 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
572 /* Change our root directory */
573 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
574 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
576 if (chdir("/") == -1)
577 fatal("chdir(\"/\"): %s", strerror(errno));
579 /* Drop our privileges */
580 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
583 /* XXX not ready, too heavy after chroot */
584 do_setusercontext(pw);
586 gidset[0] = pw->pw_gid;
587 if (setgroups(1, gidset) < 0)
588 fatal("setgroups: %.100s", strerror(errno));
589 permanently_set_uid(pw);
594 privsep_preauth(Authctxt *authctxt)
599 /* Set up unprivileged child process to deal with network data */
600 pmonitor = monitor_init();
601 /* Store a pointer to the kex for later rekeying */
602 pmonitor->m_pkex = &xxx_kex;
606 fatal("fork of unprivileged child failed");
607 } else if (pid != 0) {
608 debug2("Network child is on pid %ld", (long)pid);
610 close(pmonitor->m_recvfd);
611 pmonitor->m_pid = pid;
612 monitor_child_preauth(authctxt, pmonitor);
613 close(pmonitor->m_sendfd);
616 monitor_sync(pmonitor);
618 /* Wait for the child's exit status */
619 while (waitpid(pid, &status, 0) < 0)
626 close(pmonitor->m_sendfd);
628 /* Demote the child */
629 if (getuid() == 0 || geteuid() == 0)
630 privsep_preauth_child();
631 setproctitle("%s", "[net]");
637 privsep_postauth(Authctxt *authctxt)
639 #ifdef DISABLE_FD_PASSING
642 if (authctxt->pw->pw_uid == 0 || options.use_login) {
644 /* File descriptor passing is broken or root login */
645 monitor_apply_keystate(pmonitor);
650 /* Authentication complete */
652 if (startup_pipe != -1) {
657 /* New socket pair */
658 monitor_reinit(pmonitor);
660 pmonitor->m_pid = fork();
661 if (pmonitor->m_pid == -1)
662 fatal("fork of unprivileged child failed");
663 else if (pmonitor->m_pid != 0) {
664 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
665 close(pmonitor->m_recvfd);
666 monitor_child_postauth(pmonitor);
672 close(pmonitor->m_sendfd);
674 /* Demote the private keys to public keys. */
675 demote_sensitive_data();
677 /* Drop privileges */
678 do_setusercontext(authctxt->pw);
680 /* It is safe now to apply the key state */
681 monitor_apply_keystate(pmonitor);
685 list_hostkey_types(void)
693 for (i = 0; i < options.num_host_key_files; i++) {
694 Key *key = sensitive_data.host_keys[i];
700 if (buffer_len(&b) > 0)
701 buffer_append(&b, ",", 1);
702 p = key_ssh_name(key);
703 buffer_append(&b, p, strlen(p));
707 buffer_append(&b, "\0", 1);
708 ret = xstrdup(buffer_ptr(&b));
710 debug("list_hostkey_types: %s", ret);
715 get_hostkey_by_type(int type)
719 for (i = 0; i < options.num_host_key_files; i++) {
720 Key *key = sensitive_data.host_keys[i];
721 if (key != NULL && key->type == type)
728 get_hostkey_by_index(int ind)
730 if (ind < 0 || ind >= options.num_host_key_files)
732 return (sensitive_data.host_keys[ind]);
736 get_hostkey_index(Key *key)
740 for (i = 0; i < options.num_host_key_files; i++) {
741 if (key == sensitive_data.host_keys[i])
748 * returns 1 if connection should be dropped, 0 otherwise.
749 * dropping starts at connection #max_startups_begin with a probability
750 * of (max_startups_rate/100). the probability increases linearly until
751 * all connections are dropped for startups > max_startups
754 drop_connection(int startups)
758 if (startups < options.max_startups_begin)
760 if (startups >= options.max_startups)
762 if (options.max_startups_rate == 100)
765 p = 100 - options.max_startups_rate;
766 p *= startups - options.max_startups_begin;
767 p /= (double) (options.max_startups - options.max_startups_begin);
768 p += options.max_startups_rate;
770 r = arc4random() / (double) UINT_MAX;
772 debug("drop_connection: p %g, r %g", p, r);
773 return (r < p) ? 1 : 0;
779 fprintf(stderr, "%s, %s\n",
780 SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
782 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
783 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
789 send_rexec_state(int fd, Buffer *conf)
793 debug3("%s: entering fd = %d config len %d", __func__, fd,
797 * Protocol from reexec master to child:
798 * string configuration
799 * u_int ephemeral_key_follows
800 * bignum e (only if ephemeral_key_follows == 1)
808 buffer_put_cstring(&m, buffer_ptr(conf));
810 if (sensitive_data.server_key != NULL &&
811 sensitive_data.server_key->type == KEY_RSA1) {
812 buffer_put_int(&m, 1);
813 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
814 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
815 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
816 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
817 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
818 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
820 buffer_put_int(&m, 0);
822 if (ssh_msg_send(fd, 0, &m) == -1)
823 fatal("%s: ssh_msg_send failed", __func__);
827 debug3("%s: done", __func__);
831 recv_rexec_state(int fd, Buffer *conf)
837 debug3("%s: entering fd = %d", __func__, fd);
841 if (ssh_msg_recv(fd, &m) == -1)
842 fatal("%s: ssh_msg_recv failed", __func__);
843 if (buffer_get_char(&m) != 0)
844 fatal("%s: rexec version mismatch", __func__);
846 cp = buffer_get_string(&m, &len);
848 buffer_append(conf, cp, len + 1);
851 if (buffer_get_int(&m)) {
852 if (sensitive_data.server_key != NULL)
853 key_free(sensitive_data.server_key);
854 sensitive_data.server_key = key_new_private(KEY_RSA1);
855 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
856 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
857 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
858 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
859 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
860 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
861 rsa_generate_additional_parameters(
862 sensitive_data.server_key->rsa);
866 debug3("%s: done", __func__);
870 * Main program for the daemon.
873 main(int ac, char **av)
877 int opt, j, i, fdsetsz, on = 1;
878 int sock_in = -1, sock_out = -1, newsock = -1;
882 struct sockaddr_storage from;
883 const char *remote_ip;
887 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
889 int listen_sock, maxfd;
890 int startup_p[2], config_s[2];
894 int ret, key_used = 0;
897 #ifdef HAVE_SECUREWARE
898 (void)set_auth_parameters(ac, av);
900 __progname = ssh_get_progname(av[0]);
903 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
906 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
907 for (i = 0; i < ac; i++)
908 saved_argv[i] = xstrdup(av[i]);
909 saved_argv[i] = NULL;
911 #ifndef HAVE_SETPROCTITLE
912 /* Prepare for later setproctitle emulation */
913 compat_init_setproctitle(ac, av);
917 if (geteuid() == 0 && setgroups(0, NULL) == -1)
918 debug("setgroups(): %.200s", strerror(errno));
920 /* Initialize configuration options to their default values. */
921 initialize_server_options(&options);
923 /* Parse command-line arguments. */
924 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
933 config_file_name = optarg;
936 if (debug_flag == 0) {
938 options.log_level = SYSLOG_LEVEL_DEBUG1;
939 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
962 options.log_level = SYSLOG_LEVEL_QUIET;
965 options.server_key_bits = atoi(optarg);
968 options.ports_from_cmdline = 1;
969 if (options.num_ports >= MAX_PORTS) {
970 fprintf(stderr, "too many ports.\n");
973 options.ports[options.num_ports++] = a2port(optarg);
974 if (options.ports[options.num_ports-1] == 0) {
975 fprintf(stderr, "Bad port number.\n");
980 if ((options.login_grace_time = convtime(optarg)) == -1) {
981 fprintf(stderr, "Invalid login grace time.\n");
986 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
987 fprintf(stderr, "Invalid key regeneration interval.\n");
992 if (options.num_host_key_files >= MAX_HOSTKEYS) {
993 fprintf(stderr, "too many host keys.\n");
996 options.host_key_files[options.num_host_key_files++] = optarg;
1002 utmp_len = atoi(optarg);
1003 if (utmp_len > MAXHOSTNAMELEN) {
1004 fprintf(stderr, "Invalid utmp length.\n");
1009 line = xstrdup(optarg);
1010 if (process_server_config_line(&options, line,
1011 "command-line", 0) != 0)
1021 if (rexeced_flag || inetd_flag)
1023 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1024 fatal("sshd re-exec requires execution with an absolute path");
1026 closefrom(REEXEC_MIN_FREE_FD);
1028 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1030 SSLeay_add_all_algorithms();
1031 channel_set_af(IPv4or6);
1034 * Force logging to stderr until we have loaded the private host
1035 * key (unless started from inetd)
1037 log_init(__progname,
1038 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1039 SYSLOG_LEVEL_INFO : options.log_level,
1040 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1041 SYSLOG_FACILITY_AUTH : options.log_facility,
1042 log_stderr || !inetd_flag);
1046 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1047 * root's environment
1049 unsetenv("KRB5CCNAME");
1052 /* Cray can define user privs drop all privs now!
1053 * Not needed on PRIV_SU systems!
1060 sensitive_data.server_key = NULL;
1061 sensitive_data.ssh1_host_key = NULL;
1062 sensitive_data.have_ssh1_key = 0;
1063 sensitive_data.have_ssh2_key = 0;
1065 /* Fetch our configuration */
1068 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1070 load_server_config(config_file_name, &cfg);
1072 parse_server_config(&options,
1073 rexeced_flag ? "rexec" : config_file_name, &cfg);
1078 /* Fill in default values for those options not explicitly set. */
1079 fill_default_server_options(&options);
1081 /* Check that there are no remaining arguments. */
1083 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1087 debug("sshd version %.100s", SSH_VERSION);
1089 /* load private host keys */
1090 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1092 for (i = 0; i < options.num_host_key_files; i++)
1093 sensitive_data.host_keys[i] = NULL;
1095 for (i = 0; i < options.num_host_key_files; i++) {
1096 key = key_load_private(options.host_key_files[i], "", NULL);
1097 sensitive_data.host_keys[i] = key;
1099 error("Could not load host key: %s",
1100 options.host_key_files[i]);
1101 sensitive_data.host_keys[i] = NULL;
1104 switch (key->type) {
1106 sensitive_data.ssh1_host_key = key;
1107 sensitive_data.have_ssh1_key = 1;
1111 sensitive_data.have_ssh2_key = 1;
1114 debug("private host key: #%d type %d %s", i, key->type,
1117 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1118 logit("Disabling protocol version 1. Could not load host key");
1119 options.protocol &= ~SSH_PROTO_1;
1121 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1122 logit("Disabling protocol version 2. Could not load host key");
1123 options.protocol &= ~SSH_PROTO_2;
1125 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1126 logit("sshd: no hostkeys available -- exiting.");
1130 /* Check certain values for sanity. */
1131 if (options.protocol & SSH_PROTO_1) {
1132 if (options.server_key_bits < 512 ||
1133 options.server_key_bits > 32768) {
1134 fprintf(stderr, "Bad server key size.\n");
1138 * Check that server and host key lengths differ sufficiently. This
1139 * is necessary to make double encryption work with rsaref. Oh, I
1140 * hate software patents. I dont know if this can go? Niels
1142 if (options.server_key_bits >
1143 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1144 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1145 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1146 SSH_KEY_BITS_RESERVED) {
1147 options.server_key_bits =
1148 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1149 SSH_KEY_BITS_RESERVED;
1150 debug("Forcing server key to %d bits to make it differ from host key.",
1151 options.server_key_bits);
1159 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1160 fatal("Privilege separation user %s does not exist",
1162 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1163 (S_ISDIR(st.st_mode) == 0))
1164 fatal("Missing privilege separation directory: %s",
1165 _PATH_PRIVSEP_CHROOT_DIR);
1168 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1169 (st.st_uid != getuid () ||
1170 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1172 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1174 fatal("%s must be owned by root and not group or "
1175 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1178 /* Configuration looks good, so exit if in test mode. */
1183 * Clear out any supplemental groups we may have inherited. This
1184 * prevents inadvertent creation of files with bad modes (in the
1185 * portable version at least, it's certainly possible for PAM
1186 * to create a file, and we can't control the code in every
1187 * module which might be used).
1189 if (setgroups(0, NULL) < 0)
1190 debug("setgroups() failed: %.200s", strerror(errno));
1193 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1194 for (i = 0; i < rexec_argc; i++) {
1195 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1196 rexec_argv[i] = saved_argv[i];
1198 rexec_argv[rexec_argc] = "-R";
1199 rexec_argv[rexec_argc + 1] = NULL;
1202 /* Initialize the log (it is reinitialized below in case we forked). */
1203 if (debug_flag && !inetd_flag)
1205 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1208 * If not in debugging mode, and not started from inetd, disconnect
1209 * from the controlling terminal, and fork. The original process
1212 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1215 #endif /* TIOCNOTTY */
1216 if (daemon(0, 0) < 0)
1217 fatal("daemon() failed: %.200s", strerror(errno));
1219 /* Disconnect from the controlling tty. */
1221 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1223 (void) ioctl(fd, TIOCNOTTY, NULL);
1226 #endif /* TIOCNOTTY */
1228 /* Reinitialize the log (because of the fork above). */
1229 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1231 /* Initialize the random number generator. */
1234 /* Chdir to the root directory so that the current disk can be
1235 unmounted if desired. */
1238 /* ignore SIGPIPE */
1239 signal(SIGPIPE, SIG_IGN);
1241 /* Start listening for a socket, unless started from inetd. */
1247 close(REEXEC_CONFIG_PASS_FD);
1248 sock_in = sock_out = dup(STDIN_FILENO);
1250 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1251 close(REEXEC_STARTUP_PIPE_FD);
1254 sock_in = dup(STDIN_FILENO);
1255 sock_out = dup(STDOUT_FILENO);
1258 * We intentionally do not close the descriptors 0, 1, and 2
1259 * as our code for setting the descriptors won't work if
1260 * ttyfd happens to be one of those.
1262 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1263 dup2(fd, STDIN_FILENO);
1264 dup2(fd, STDOUT_FILENO);
1265 if (fd > STDOUT_FILENO)
1268 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1269 if ((options.protocol & SSH_PROTO_1) &&
1270 sensitive_data.server_key == NULL)
1271 generate_ephemeral_server_key();
1273 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1274 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1276 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1277 fatal("Too many listen sockets. "
1278 "Enlarge MAX_LISTEN_SOCKS");
1279 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1280 ntop, sizeof(ntop), strport, sizeof(strport),
1281 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1282 error("getnameinfo failed");
1285 /* Create socket for listening. */
1286 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1288 if (listen_sock < 0) {
1289 /* kernel may not support ipv6 */
1290 verbose("socket: %.100s", strerror(errno));
1293 if (set_nonblock(listen_sock) == -1) {
1298 * Set socket options.
1299 * Allow local port reuse in TIME_WAIT.
1301 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1302 &on, sizeof(on)) == -1)
1303 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1305 debug("Bind to port %s on %s.", strport, ntop);
1307 /* Bind the socket to the desired port. */
1308 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1310 error("Bind to port %s on %s failed: %.200s.",
1311 strport, ntop, strerror(errno));
1315 listen_socks[num_listen_socks] = listen_sock;
1318 /* Start listening on the port. */
1319 logit("Server listening on %s port %s.", ntop, strport);
1320 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1321 fatal("listen: %.100s", strerror(errno));
1324 freeaddrinfo(options.listen_addrs);
1326 if (!num_listen_socks)
1327 fatal("Cannot bind any address.");
1329 if (options.protocol & SSH_PROTO_1)
1330 generate_ephemeral_server_key();
1333 * Arrange to restart on SIGHUP. The handler needs
1336 signal(SIGHUP, sighup_handler);
1338 signal(SIGTERM, sigterm_handler);
1339 signal(SIGQUIT, sigterm_handler);
1341 /* Arrange SIGCHLD to be caught. */
1342 signal(SIGCHLD, main_sigchld_handler);
1344 /* Write out the pid file after the sigterm handler is setup */
1347 * Record our pid in /var/run/sshd.pid to make it
1348 * easier to kill the correct sshd. We don't want to
1349 * do this before the bind above because the bind will
1350 * fail if there already is a daemon, and this will
1351 * overwrite any old pid in the file.
1353 f = fopen(options.pid_file, "wb");
1355 error("Couldn't create pid file \"%s\": %s",
1356 options.pid_file, strerror(errno));
1358 fprintf(f, "%ld\n", (long) getpid());
1363 /* setup fd set for listen */
1366 for (i = 0; i < num_listen_socks; i++)
1367 if (listen_socks[i] > maxfd)
1368 maxfd = listen_socks[i];
1369 /* pipes connected to unauthenticated childs */
1370 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1371 for (i = 0; i < options.max_startups; i++)
1372 startup_pipes[i] = -1;
1375 * Stay listening for connections until the system crashes or
1376 * the daemon is killed with a signal.
1379 if (received_sighup)
1383 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1384 fdset = (fd_set *)xmalloc(fdsetsz);
1385 memset(fdset, 0, fdsetsz);
1387 for (i = 0; i < num_listen_socks; i++)
1388 FD_SET(listen_socks[i], fdset);
1389 for (i = 0; i < options.max_startups; i++)
1390 if (startup_pipes[i] != -1)
1391 FD_SET(startup_pipes[i], fdset);
1393 /* Wait in select until there is a connection. */
1394 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1395 if (ret < 0 && errno != EINTR)
1396 error("select: %.100s", strerror(errno));
1397 if (received_sigterm) {
1398 logit("Received signal %d; terminating.",
1399 (int) received_sigterm);
1400 close_listen_socks();
1401 unlink(options.pid_file);
1404 if (key_used && key_do_regen) {
1405 generate_ephemeral_server_key();
1412 for (i = 0; i < options.max_startups; i++)
1413 if (startup_pipes[i] != -1 &&
1414 FD_ISSET(startup_pipes[i], fdset)) {
1416 * the read end of the pipe is ready
1417 * if the child has closed the pipe
1418 * after successful authentication
1419 * or if the child has died
1421 close(startup_pipes[i]);
1422 startup_pipes[i] = -1;
1425 for (i = 0; i < num_listen_socks; i++) {
1426 if (!FD_ISSET(listen_socks[i], fdset))
1428 fromlen = sizeof(from);
1429 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1432 if (errno != EINTR && errno != EWOULDBLOCK)
1433 error("accept: %.100s", strerror(errno));
1436 if (unset_nonblock(newsock) == -1) {
1440 if (drop_connection(startups) == 1) {
1441 debug("drop connection #%d", startups);
1445 if (pipe(startup_p) == -1) {
1450 if (rexec_flag && socketpair(AF_UNIX,
1451 SOCK_STREAM, 0, config_s) == -1) {
1452 error("reexec socketpair: %s",
1455 close(startup_p[0]);
1456 close(startup_p[1]);
1460 for (j = 0; j < options.max_startups; j++)
1461 if (startup_pipes[j] == -1) {
1462 startup_pipes[j] = startup_p[0];
1463 if (maxfd < startup_p[0])
1464 maxfd = startup_p[0];
1470 * Got connection. Fork a child to handle it, unless
1471 * we are in debugging mode.
1475 * In debugging mode. Close the listening
1476 * socket, and start processing the
1477 * connection without forking.
1479 debug("Server will not fork when running in debugging mode.");
1480 close_listen_socks();
1483 close(startup_p[0]);
1484 close(startup_p[1]);
1488 send_rexec_state(config_s[0],
1495 * Normal production daemon. Fork, and have
1496 * the child process the connection. The
1497 * parent continues listening.
1499 if ((pid = fork()) == 0) {
1501 * Child. Close the listening and max_startup
1502 * sockets. Start using the accepted socket.
1503 * Reinitialize logging (since our pid has
1504 * changed). We break out of the loop to handle
1507 startup_pipe = startup_p[1];
1508 close_startup_pipes();
1509 close_listen_socks();
1512 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1518 /* Parent. Stay in the loop. */
1520 error("fork: %.100s", strerror(errno));
1522 debug("Forked child %ld.", (long)pid);
1524 close(startup_p[1]);
1527 send_rexec_state(config_s[0], &cfg);
1532 /* Mark that the key has been used (it was "given" to the child). */
1533 if ((options.protocol & SSH_PROTO_1) &&
1535 /* Schedule server key regeneration alarm. */
1536 signal(SIGALRM, key_regeneration_alarm);
1537 alarm(options.key_regeneration_time);
1543 /* Close the new socket (the child is now taking care of it). */
1546 /* child process check (or debug mode) */
1547 if (num_listen_socks < 0)
1552 /* This is the child processing a new connection. */
1553 setproctitle("%s", "[accepted]");
1558 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1559 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1560 dup2(newsock, STDIN_FILENO);
1561 dup2(STDIN_FILENO, STDOUT_FILENO);
1562 if (startup_pipe == -1)
1563 close(REEXEC_STARTUP_PIPE_FD);
1565 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1567 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1569 close(startup_pipe);
1571 execv(rexec_argv[0], rexec_argv);
1573 /* Reexec has failed, fall back and continue */
1574 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1575 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1576 log_init(__progname, options.log_level,
1577 options.log_facility, log_stderr);
1580 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1582 close(REEXEC_CONFIG_PASS_FD);
1583 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1584 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1585 dup2(fd, STDIN_FILENO);
1586 dup2(fd, STDOUT_FILENO);
1587 if (fd > STDERR_FILENO)
1590 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1591 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1595 * Create a new session and process group since the 4.4BSD
1596 * setlogin() affects the entire process group. We don't
1597 * want the child to be able to affect the parent.
1599 #if !defined(SSHD_ACQUIRES_CTTY)
1601 * If setsid is called, on some platforms sshd will later acquire a
1602 * controlling terminal which will result in "could not set
1603 * controlling tty" errors.
1605 if (!debug_flag && !inetd_flag && setsid() < 0)
1606 error("setsid: %.100s", strerror(errno));
1610 * Disable the key regeneration alarm. We will not regenerate the
1611 * key since we are no longer in a position to give it to anyone. We
1612 * will not restart on SIGHUP since it no longer makes sense.
1615 signal(SIGALRM, SIG_DFL);
1616 signal(SIGHUP, SIG_DFL);
1617 signal(SIGTERM, SIG_DFL);
1618 signal(SIGQUIT, SIG_DFL);
1619 signal(SIGCHLD, SIG_DFL);
1620 signal(SIGINT, SIG_DFL);
1622 /* Set SO_KEEPALIVE if requested. */
1623 if (options.tcp_keep_alive &&
1624 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1626 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1629 * Register our connection. This turns encryption off because we do
1632 packet_set_connection(sock_in, sock_out);
1634 remote_port = get_remote_port();
1635 remote_ip = get_remote_ipaddr();
1638 /* Check whether logins are denied from this host. */
1639 if (packet_connection_is_on_socket()) {
1640 struct request_info req;
1642 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1645 if (!hosts_access(&req)) {
1646 debug("Connection refused by tcp wrapper");
1649 fatal("libwrap refuse returns");
1652 #endif /* LIBWRAP */
1654 /* Log the connection. */
1655 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1658 * We don\'t want to listen forever unless the other side
1659 * successfully authenticates itself. So we set up an alarm which is
1660 * cleared after successful authentication. A limit of zero
1661 * indicates no limit. Note that we don\'t set the alarm in debugging
1662 * mode; it is just annoying to have the server exit just when you
1663 * are about to discover the bug.
1665 signal(SIGALRM, grace_alarm_handler);
1667 alarm(options.login_grace_time);
1669 sshd_exchange_identification(sock_in, sock_out);
1671 packet_set_nonblocking();
1673 /* prepare buffers to collect authentication messages */
1674 buffer_init(&loginmsg);
1676 /* allocate authentication context */
1677 authctxt = xmalloc(sizeof(*authctxt));
1678 memset(authctxt, 0, sizeof(*authctxt));
1680 /* XXX global for cleanup, access from other modules */
1681 the_authctxt = authctxt;
1684 if (privsep_preauth(authctxt) == 1)
1687 /* perform the key exchange */
1688 /* authenticate user and start session */
1691 do_authentication2(authctxt);
1694 do_authentication(authctxt);
1697 * If we use privilege separation, the unprivileged child transfers
1698 * the current keystate and exits
1701 mm_send_keystate(pmonitor);
1707 * In privilege separation, we fork another child and prepare
1708 * file descriptor passing.
1711 privsep_postauth(authctxt);
1712 /* the monitor process [priv] will not return */
1714 destroy_sensitive_data();
1717 /* Start session. */
1718 do_authenticated(authctxt);
1720 /* The connection has been terminated. */
1721 verbose("Closing connection to %.100s", remote_ip);
1724 if (options.use_pam)
1726 #endif /* USE_PAM */
1737 * Decrypt session_key_int using our private server key and private host key
1738 * (key with larger modulus first).
1741 ssh1_session_key(BIGNUM *session_key_int)
1745 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1746 /* Server key has bigger modulus. */
1747 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1748 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1749 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1750 get_remote_ipaddr(),
1751 BN_num_bits(sensitive_data.server_key->rsa->n),
1752 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1753 SSH_KEY_BITS_RESERVED);
1755 if (rsa_private_decrypt(session_key_int, session_key_int,
1756 sensitive_data.server_key->rsa) <= 0)
1758 if (rsa_private_decrypt(session_key_int, session_key_int,
1759 sensitive_data.ssh1_host_key->rsa) <= 0)
1762 /* Host key has bigger modulus (or they are equal). */
1763 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1764 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1765 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1766 get_remote_ipaddr(),
1767 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1768 BN_num_bits(sensitive_data.server_key->rsa->n),
1769 SSH_KEY_BITS_RESERVED);
1771 if (rsa_private_decrypt(session_key_int, session_key_int,
1772 sensitive_data.ssh1_host_key->rsa) < 0)
1774 if (rsa_private_decrypt(session_key_int, session_key_int,
1775 sensitive_data.server_key->rsa) < 0)
1788 BIGNUM *session_key_int;
1789 u_char session_key[SSH_SESSION_KEY_LENGTH];
1791 u_int cipher_type, auth_mask, protocol_flags;
1795 * Generate check bytes that the client must send back in the user
1796 * packet in order for it to be accepted; this is used to defy ip
1797 * spoofing attacks. Note that this only works against somebody
1798 * doing IP spoofing from a remote machine; any machine on the local
1799 * network can still see outgoing packets and catch the random
1800 * cookie. This only affects rhosts authentication, and this is one
1801 * of the reasons why it is inherently insecure.
1803 for (i = 0; i < 8; i++) {
1806 cookie[i] = rnd & 0xff;
1811 * Send our public key. We include in the packet 64 bits of random
1812 * data that must be matched in the reply in order to prevent IP
1815 packet_start(SSH_SMSG_PUBLIC_KEY);
1816 for (i = 0; i < 8; i++)
1817 packet_put_char(cookie[i]);
1819 /* Store our public server RSA key. */
1820 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1821 packet_put_bignum(sensitive_data.server_key->rsa->e);
1822 packet_put_bignum(sensitive_data.server_key->rsa->n);
1824 /* Store our public host RSA key. */
1825 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1826 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1827 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1829 /* Put protocol flags. */
1830 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1832 /* Declare which ciphers we support. */
1833 packet_put_int(cipher_mask_ssh1(0));
1835 /* Declare supported authentication types. */
1837 if (options.rhosts_rsa_authentication)
1838 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1839 if (options.rsa_authentication)
1840 auth_mask |= 1 << SSH_AUTH_RSA;
1841 if (options.challenge_response_authentication == 1)
1842 auth_mask |= 1 << SSH_AUTH_TIS;
1843 if (options.password_authentication)
1844 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1845 packet_put_int(auth_mask);
1847 /* Send the packet and wait for it to be sent. */
1849 packet_write_wait();
1851 debug("Sent %d bit server key and %d bit host key.",
1852 BN_num_bits(sensitive_data.server_key->rsa->n),
1853 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1855 /* Read clients reply (cipher type and session key). */
1856 packet_read_expect(SSH_CMSG_SESSION_KEY);
1858 /* Get cipher type and check whether we accept this. */
1859 cipher_type = packet_get_char();
1861 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1862 packet_disconnect("Warning: client selects unsupported cipher.");
1864 /* Get check bytes from the packet. These must match those we
1865 sent earlier with the public key packet. */
1866 for (i = 0; i < 8; i++)
1867 if (cookie[i] != packet_get_char())
1868 packet_disconnect("IP Spoofing check bytes do not match.");
1870 debug("Encryption type: %.200s", cipher_name(cipher_type));
1872 /* Get the encrypted integer. */
1873 if ((session_key_int = BN_new()) == NULL)
1874 fatal("do_ssh1_kex: BN_new failed");
1875 packet_get_bignum(session_key_int);
1877 protocol_flags = packet_get_int();
1878 packet_set_protocol_flags(protocol_flags);
1881 /* Decrypt session_key_int using host/server keys */
1882 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1885 * Extract session key from the decrypted integer. The key is in the
1886 * least significant 256 bits of the integer; the first byte of the
1887 * key is in the highest bits.
1890 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1891 len = BN_num_bytes(session_key_int);
1892 if (len < 0 || len > sizeof(session_key)) {
1893 error("do_connection: bad session key len from %s: "
1894 "session_key_int %d > sizeof(session_key) %lu",
1895 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1898 memset(session_key, 0, sizeof(session_key));
1899 BN_bn2bin(session_key_int,
1900 session_key + sizeof(session_key) - len);
1902 derive_ssh1_session_id(
1903 sensitive_data.ssh1_host_key->rsa->n,
1904 sensitive_data.server_key->rsa->n,
1905 cookie, session_id);
1907 * Xor the first 16 bytes of the session key with the
1910 for (i = 0; i < 16; i++)
1911 session_key[i] ^= session_id[i];
1915 int bytes = BN_num_bytes(session_key_int);
1916 u_char *buf = xmalloc(bytes);
1919 logit("do_connection: generating a fake encryption key");
1920 BN_bn2bin(session_key_int, buf);
1922 MD5_Update(&md, buf, bytes);
1923 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1924 MD5_Final(session_key, &md);
1926 MD5_Update(&md, session_key, 16);
1927 MD5_Update(&md, buf, bytes);
1928 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1929 MD5_Final(session_key + 16, &md);
1930 memset(buf, 0, bytes);
1932 for (i = 0; i < 16; i++)
1933 session_id[i] = session_key[i] ^ session_key[i + 16];
1935 /* Destroy the private and public keys. No longer. */
1936 destroy_sensitive_data();
1939 mm_ssh1_session_id(session_id);
1941 /* Destroy the decrypted integer. It is no longer needed. */
1942 BN_clear_free(session_key_int);
1944 /* Set the session key. From this on all communications will be encrypted. */
1945 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1947 /* Destroy our copy of the session key. It is no longer needed. */
1948 memset(session_key, 0, sizeof(session_key));
1950 debug("Received session key; encryption turned on.");
1952 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1953 packet_start(SSH_SMSG_SUCCESS);
1955 packet_write_wait();
1959 * SSH2 key exchange: diffie-hellman-group1-sha1
1966 if (options.ciphers != NULL) {
1967 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1968 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1970 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1971 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1972 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1973 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1975 if (options.macs != NULL) {
1976 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1977 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1979 if (!options.compression) {
1980 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1981 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1983 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1985 /* start key exchange */
1986 kex = kex_setup(myproposal);
1987 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1988 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1989 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1991 kex->client_version_string=client_version_string;
1992 kex->server_version_string=server_version_string;
1993 kex->load_host_key=&get_hostkey_by_type;
1994 kex->host_key_index=&get_hostkey_index;
1998 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2000 session_id2 = kex->session_id;
2001 session_id2_len = kex->session_id_len;
2004 /* send 1st encrypted/maced/compressed message */
2005 packet_start(SSH2_MSG_IGNORE);
2006 packet_put_cstring("markus");
2008 packet_write_wait();
2013 /* server specific fatal cleanup */
2018 do_cleanup(the_authctxt);