1 /* $OpenBSD: sshd.c,v 1.344 2006/08/05 07:52:52 dtucker Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This program is the ssh daemon. It listens for connections from clients,
7 * and performs authentication, executes use commands or shell, and forwards
8 * information to/from the application to the user client over an encrypted
9 * connection. This can also handle forwarding of X11, TCP/IP, and
10 * authentication agent connections.
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
18 * SSH2 implementation:
19 * Privilege Separation:
21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22 * Copyright (c) 2002 Niels Provos. All rights reserved.
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
47 #include <sys/types.h>
48 #include <sys/ioctl.h>
49 #include <sys/socket.h>
50 #ifdef HAVE_SYS_STAT_H
51 # include <sys/stat.h>
53 #ifdef HAVE_SYS_TIME_H
54 # include <sys/time.h>
56 #include "openbsd-compat/sys-tree.h"
73 #include <openssl/dh.h>
74 #include <openssl/bn.h>
75 #include <openssl/md5.h>
76 #include <openssl/rand.h>
77 #ifdef HAVE_SECUREWARE
78 #include <sys/security.h>
98 #include "myproposal.h"
100 #include "pathnames.h"
101 #include "atomicio.h"
102 #include "canohost.h"
103 #include "hostfile.h"
107 #include "dispatch.h"
108 #include "channels.h"
110 #include "monitor_mm.h"
115 #include "monitor_wrap.h"
116 #include "monitor_fdpass.h"
122 int allow_severity = LOG_INFO;
123 int deny_severity = LOG_WARNING;
131 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
132 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
133 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
134 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
136 extern char *__progname;
138 /* Server configuration options. */
139 ServerOptions options;
141 /* Name of the server configuration file. */
142 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
145 * Debug mode flag. This can be set on the command line. If debug
146 * mode is enabled, extra debugging output will be sent to the system
147 * log, the daemon will not go to background, and will exit after processing
148 * the first connection.
152 /* Flag indicating that the daemon should only test the configuration and keys. */
155 /* Flag indicating that the daemon is being started from inetd. */
158 /* Flag indicating that sshd should not detach and become a daemon. */
159 int no_daemon_flag = 0;
161 /* debug goes to stderr unless inetd_flag is set */
164 /* Saved arguments to main(). */
169 int rexeced_flag = 0;
175 * The sockets that the server is listening; this is used in the SIGHUP
178 #define MAX_LISTEN_SOCKS 16
179 int listen_socks[MAX_LISTEN_SOCKS];
180 int num_listen_socks = 0;
183 * the client's version string, passed by sshd2 in compat mode. if != NULL,
184 * sshd will skip the version-number exchange
186 char *client_version_string = NULL;
187 char *server_version_string = NULL;
189 /* for rekeying XXX fixme */
193 * Any really sensitive data in the application is contained in this
194 * structure. The idea is that this structure could be locked into memory so
195 * that the pages do not get written into swap. However, there are some
196 * problems. The private key contains BIGNUMs, and we do not (in principle)
197 * have access to the internals of them, and locking just the structure is
198 * not very useful. Currently, memory locking is not implemented.
201 Key *server_key; /* ephemeral server key */
202 Key *ssh1_host_key; /* ssh1 host key */
203 Key **host_keys; /* all private host keys */
206 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
210 * Flag indicating whether the RSA server key needs to be regenerated.
211 * Is set in the SIGALRM handler and cleared when the key is regenerated.
213 static volatile sig_atomic_t key_do_regen = 0;
215 /* This is set to true when a signal is received. */
216 static volatile sig_atomic_t received_sighup = 0;
217 static volatile sig_atomic_t received_sigterm = 0;
219 /* session identifier, used by RSA-auth */
220 u_char session_id[16];
223 u_char *session_id2 = NULL;
224 u_int session_id2_len = 0;
226 /* record remote hostname or ip */
227 u_int utmp_len = MAXHOSTNAMELEN;
229 /* options.max_startup sized array of fd ints */
230 int *startup_pipes = NULL;
231 int startup_pipe; /* in child */
233 /* variables used for privilege separation */
234 int use_privsep = -1;
235 struct monitor *pmonitor = NULL;
237 /* global authentication context */
238 Authctxt *the_authctxt = NULL;
240 /* sshd_config buffer */
243 /* message to be displayed after login */
246 /* Prototypes for various functions defined later in this file. */
247 void destroy_sensitive_data(void);
248 void demote_sensitive_data(void);
250 static void do_ssh1_kex(void);
251 static void do_ssh2_kex(void);
254 * Close all listening sockets
257 close_listen_socks(void)
261 for (i = 0; i < num_listen_socks; i++)
262 close(listen_socks[i]);
263 num_listen_socks = -1;
267 close_startup_pipes(void)
272 for (i = 0; i < options.max_startups; i++)
273 if (startup_pipes[i] != -1)
274 close(startup_pipes[i]);
278 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
279 * the effect is to reread the configuration file (and to regenerate
285 sighup_handler(int sig)
287 int save_errno = errno;
290 signal(SIGHUP, sighup_handler);
295 * Called from the main program after receiving SIGHUP.
296 * Restarts the server.
301 logit("Received SIGHUP; restarting.");
302 close_listen_socks();
303 close_startup_pipes();
304 execv(saved_argv[0], saved_argv);
305 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
311 * Generic signal handler for terminating signals in the master daemon.
315 sigterm_handler(int sig)
317 received_sigterm = sig;
321 * SIGCHLD handler. This is called whenever a child dies. This will then
322 * reap any zombies left by exited children.
326 main_sigchld_handler(int sig)
328 int save_errno = errno;
332 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
333 (pid < 0 && errno == EINTR))
336 signal(SIGCHLD, main_sigchld_handler);
341 * Signal handler for the alarm after the login grace period has expired.
345 grace_alarm_handler(int sig)
347 /* XXX no idea how fix this signal handler */
349 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
350 kill(pmonitor->m_pid, SIGALRM);
352 /* Log error and exit. */
353 fatal("Timeout before authentication for %s", get_remote_ipaddr());
357 * Signal handler for the key regeneration alarm. Note that this
358 * alarm only occurs in the daemon waiting for connections, and it does not
359 * do anything with the private key or random state before forking.
360 * Thus there should be no concurrency control/asynchronous execution
364 generate_ephemeral_server_key(void)
369 verbose("Generating %s%d bit RSA key.",
370 sensitive_data.server_key ? "new " : "", options.server_key_bits);
371 if (sensitive_data.server_key != NULL)
372 key_free(sensitive_data.server_key);
373 sensitive_data.server_key = key_generate(KEY_RSA1,
374 options.server_key_bits);
375 verbose("RSA key generation complete.");
377 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
380 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
388 key_regeneration_alarm(int sig)
390 int save_errno = errno;
392 signal(SIGALRM, SIG_DFL);
398 sshd_exchange_identification(int sock_in, int sock_out)
402 int remote_major, remote_minor;
405 char buf[256]; /* Must not be larger than remote_version. */
406 char remote_version[256]; /* Must be at least as big as buf. */
408 if ((options.protocol & SSH_PROTO_1) &&
409 (options.protocol & SSH_PROTO_2)) {
410 major = PROTOCOL_MAJOR_1;
412 } else if (options.protocol & SSH_PROTO_2) {
413 major = PROTOCOL_MAJOR_2;
414 minor = PROTOCOL_MINOR_2;
416 major = PROTOCOL_MAJOR_1;
417 minor = PROTOCOL_MINOR_1;
419 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
420 server_version_string = xstrdup(buf);
422 /* Send our protocol version identification. */
423 if (atomicio(vwrite, sock_out, server_version_string,
424 strlen(server_version_string))
425 != strlen(server_version_string)) {
426 logit("Could not write ident string to %s", get_remote_ipaddr());
430 /* Read other sides version identification. */
431 memset(buf, 0, sizeof(buf));
432 for (i = 0; i < sizeof(buf) - 1; i++) {
433 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
434 logit("Did not receive identification string from %s",
435 get_remote_ipaddr());
438 if (buf[i] == '\r') {
440 /* Kludge for F-Secure Macintosh < 1.0.2 */
442 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
446 if (buf[i] == '\n') {
451 buf[sizeof(buf) - 1] = 0;
452 client_version_string = xstrdup(buf);
455 * Check that the versions match. In future this might accept
456 * several versions and set appropriate flags to handle them.
458 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
459 &remote_major, &remote_minor, remote_version) != 3) {
460 s = "Protocol mismatch.\n";
461 (void) atomicio(vwrite, sock_out, s, strlen(s));
464 logit("Bad protocol version identification '%.100s' from %s",
465 client_version_string, get_remote_ipaddr());
468 debug("Client protocol version %d.%d; client software version %.100s",
469 remote_major, remote_minor, remote_version);
471 compat_datafellows(remote_version);
473 if (datafellows & SSH_BUG_PROBE) {
474 logit("probed from %s with %s. Don't panic.",
475 get_remote_ipaddr(), client_version_string);
479 if (datafellows & SSH_BUG_SCANNER) {
480 logit("scanned from %s with %s. Don't panic.",
481 get_remote_ipaddr(), client_version_string);
486 switch (remote_major) {
488 if (remote_minor == 99) {
489 if (options.protocol & SSH_PROTO_2)
495 if (!(options.protocol & SSH_PROTO_1)) {
499 if (remote_minor < 3) {
500 packet_disconnect("Your ssh version is too old and "
501 "is no longer supported. Please install a newer version.");
502 } else if (remote_minor == 3) {
503 /* note that this disables agent-forwarding */
508 if (options.protocol & SSH_PROTO_2) {
517 chop(server_version_string);
518 debug("Local version string %.200s", server_version_string);
521 s = "Protocol major versions differ.\n";
522 (void) atomicio(vwrite, sock_out, s, strlen(s));
525 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
527 server_version_string, client_version_string);
532 /* Destroy the host and server keys. They will no longer be needed. */
534 destroy_sensitive_data(void)
538 if (sensitive_data.server_key) {
539 key_free(sensitive_data.server_key);
540 sensitive_data.server_key = NULL;
542 for (i = 0; i < options.num_host_key_files; i++) {
543 if (sensitive_data.host_keys[i]) {
544 key_free(sensitive_data.host_keys[i]);
545 sensitive_data.host_keys[i] = NULL;
548 sensitive_data.ssh1_host_key = NULL;
549 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
552 /* Demote private to public keys for network child */
554 demote_sensitive_data(void)
559 if (sensitive_data.server_key) {
560 tmp = key_demote(sensitive_data.server_key);
561 key_free(sensitive_data.server_key);
562 sensitive_data.server_key = tmp;
565 for (i = 0; i < options.num_host_key_files; i++) {
566 if (sensitive_data.host_keys[i]) {
567 tmp = key_demote(sensitive_data.host_keys[i]);
568 key_free(sensitive_data.host_keys[i]);
569 sensitive_data.host_keys[i] = tmp;
570 if (tmp->type == KEY_RSA1)
571 sensitive_data.ssh1_host_key = tmp;
575 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
579 privsep_preauth_child(void)
586 /* Enable challenge-response authentication for privilege separation */
587 privsep_challenge_enable();
589 for (i = 0; i < 256; i++)
590 rnd[i] = arc4random();
591 RAND_seed(rnd, sizeof(rnd));
593 /* Demote the private keys to public keys. */
594 demote_sensitive_data();
596 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
597 fatal("Privilege separation user %s does not exist",
599 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
602 /* Change our root directory */
603 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
604 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
606 if (chdir("/") == -1)
607 fatal("chdir(\"/\"): %s", strerror(errno));
609 /* Drop our privileges */
610 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
613 /* XXX not ready, too heavy after chroot */
614 do_setusercontext(pw);
616 gidset[0] = pw->pw_gid;
617 if (setgroups(1, gidset) < 0)
618 fatal("setgroups: %.100s", strerror(errno));
619 permanently_set_uid(pw);
624 privsep_preauth(Authctxt *authctxt)
629 /* Set up unprivileged child process to deal with network data */
630 pmonitor = monitor_init();
631 /* Store a pointer to the kex for later rekeying */
632 pmonitor->m_pkex = &xxx_kex;
636 fatal("fork of unprivileged child failed");
637 } else if (pid != 0) {
638 debug2("Network child is on pid %ld", (long)pid);
640 close(pmonitor->m_recvfd);
641 pmonitor->m_pid = pid;
642 monitor_child_preauth(authctxt, pmonitor);
643 close(pmonitor->m_sendfd);
646 monitor_sync(pmonitor);
648 /* Wait for the child's exit status */
649 while (waitpid(pid, &status, 0) < 0)
656 close(pmonitor->m_sendfd);
658 /* Demote the child */
659 if (getuid() == 0 || geteuid() == 0)
660 privsep_preauth_child();
661 setproctitle("%s", "[net]");
667 privsep_postauth(Authctxt *authctxt)
669 #ifdef DISABLE_FD_PASSING
672 if (authctxt->pw->pw_uid == 0 || options.use_login) {
674 /* File descriptor passing is broken or root login */
679 /* New socket pair */
680 monitor_reinit(pmonitor);
682 pmonitor->m_pid = fork();
683 if (pmonitor->m_pid == -1)
684 fatal("fork of unprivileged child failed");
685 else if (pmonitor->m_pid != 0) {
686 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
687 close(pmonitor->m_recvfd);
688 buffer_clear(&loginmsg);
689 monitor_child_postauth(pmonitor);
695 close(pmonitor->m_sendfd);
697 /* Demote the private keys to public keys. */
698 demote_sensitive_data();
700 /* Drop privileges */
701 do_setusercontext(authctxt->pw);
704 /* It is safe now to apply the key state */
705 monitor_apply_keystate(pmonitor);
708 * Tell the packet layer that authentication was successful, since
709 * this information is not part of the key state.
711 packet_set_authenticated();
715 list_hostkey_types(void)
723 for (i = 0; i < options.num_host_key_files; i++) {
724 Key *key = sensitive_data.host_keys[i];
730 if (buffer_len(&b) > 0)
731 buffer_append(&b, ",", 1);
732 p = key_ssh_name(key);
733 buffer_append(&b, p, strlen(p));
737 buffer_append(&b, "\0", 1);
738 ret = xstrdup(buffer_ptr(&b));
740 debug("list_hostkey_types: %s", ret);
745 get_hostkey_by_type(int type)
749 for (i = 0; i < options.num_host_key_files; i++) {
750 Key *key = sensitive_data.host_keys[i];
751 if (key != NULL && key->type == type)
758 get_hostkey_by_index(int ind)
760 if (ind < 0 || ind >= options.num_host_key_files)
762 return (sensitive_data.host_keys[ind]);
766 get_hostkey_index(Key *key)
770 for (i = 0; i < options.num_host_key_files; i++) {
771 if (key == sensitive_data.host_keys[i])
778 * returns 1 if connection should be dropped, 0 otherwise.
779 * dropping starts at connection #max_startups_begin with a probability
780 * of (max_startups_rate/100). the probability increases linearly until
781 * all connections are dropped for startups > max_startups
784 drop_connection(int startups)
788 if (startups < options.max_startups_begin)
790 if (startups >= options.max_startups)
792 if (options.max_startups_rate == 100)
795 p = 100 - options.max_startups_rate;
796 p *= startups - options.max_startups_begin;
797 p /= options.max_startups - options.max_startups_begin;
798 p += options.max_startups_rate;
799 r = arc4random() % 100;
801 debug("drop_connection: p %d, r %d", p, r);
802 return (r < p) ? 1 : 0;
808 fprintf(stderr, "%s, %s\n",
809 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
811 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
812 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
818 send_rexec_state(int fd, Buffer *conf)
822 debug3("%s: entering fd = %d config len %d", __func__, fd,
826 * Protocol from reexec master to child:
827 * string configuration
828 * u_int ephemeral_key_follows
829 * bignum e (only if ephemeral_key_follows == 1)
835 * string rngseed (only if OpenSSL is not self-seeded)
838 buffer_put_cstring(&m, buffer_ptr(conf));
840 if (sensitive_data.server_key != NULL &&
841 sensitive_data.server_key->type == KEY_RSA1) {
842 buffer_put_int(&m, 1);
843 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
844 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
845 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
846 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
847 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
848 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
850 buffer_put_int(&m, 0);
852 #ifndef OPENSSL_PRNG_ONLY
853 rexec_send_rng_seed(&m);
856 if (ssh_msg_send(fd, 0, &m) == -1)
857 fatal("%s: ssh_msg_send failed", __func__);
861 debug3("%s: done", __func__);
865 recv_rexec_state(int fd, Buffer *conf)
871 debug3("%s: entering fd = %d", __func__, fd);
875 if (ssh_msg_recv(fd, &m) == -1)
876 fatal("%s: ssh_msg_recv failed", __func__);
877 if (buffer_get_char(&m) != 0)
878 fatal("%s: rexec version mismatch", __func__);
880 cp = buffer_get_string(&m, &len);
882 buffer_append(conf, cp, len + 1);
885 if (buffer_get_int(&m)) {
886 if (sensitive_data.server_key != NULL)
887 key_free(sensitive_data.server_key);
888 sensitive_data.server_key = key_new_private(KEY_RSA1);
889 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
890 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
891 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
892 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
893 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
894 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
895 rsa_generate_additional_parameters(
896 sensitive_data.server_key->rsa);
899 #ifndef OPENSSL_PRNG_ONLY
900 rexec_recv_rng_seed(&m);
905 debug3("%s: done", __func__);
909 * Main program for the daemon.
912 main(int ac, char **av)
916 int opt, j, i, on = 1;
917 int sock_in = -1, sock_out = -1, newsock = -1;
921 struct sockaddr_storage from;
922 const char *remote_ip;
926 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
928 int listen_sock, maxfd;
929 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
933 int ret, key_used = 0;
935 #ifdef HAVE_SECUREWARE
936 (void)set_auth_parameters(ac, av);
938 __progname = ssh_get_progname(av[0]);
941 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
944 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
945 for (i = 0; i < ac; i++)
946 saved_argv[i] = xstrdup(av[i]);
947 saved_argv[i] = NULL;
949 #ifndef HAVE_SETPROCTITLE
950 /* Prepare for later setproctitle emulation */
951 compat_init_setproctitle(ac, av);
955 if (geteuid() == 0 && setgroups(0, NULL) == -1)
956 debug("setgroups(): %.200s", strerror(errno));
958 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
961 /* Initialize configuration options to their default values. */
962 initialize_server_options(&options);
964 /* Parse command-line arguments. */
965 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
968 options.address_family = AF_INET;
971 options.address_family = AF_INET6;
974 config_file_name = optarg;
977 if (debug_flag == 0) {
979 options.log_level = SYSLOG_LEVEL_DEBUG1;
980 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1003 options.log_level = SYSLOG_LEVEL_QUIET;
1006 options.server_key_bits = (int)strtonum(optarg, 256,
1010 options.ports_from_cmdline = 1;
1011 if (options.num_ports >= MAX_PORTS) {
1012 fprintf(stderr, "too many ports.\n");
1015 options.ports[options.num_ports++] = a2port(optarg);
1016 if (options.ports[options.num_ports-1] == 0) {
1017 fprintf(stderr, "Bad port number.\n");
1022 if ((options.login_grace_time = convtime(optarg)) == -1) {
1023 fprintf(stderr, "Invalid login grace time.\n");
1028 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1029 fprintf(stderr, "Invalid key regeneration interval.\n");
1034 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1035 fprintf(stderr, "too many host keys.\n");
1038 options.host_key_files[options.num_host_key_files++] = optarg;
1044 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1045 if (utmp_len > MAXHOSTNAMELEN) {
1046 fprintf(stderr, "Invalid utmp length.\n");
1051 line = xstrdup(optarg);
1052 if (process_server_config_line(&options, line,
1053 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1063 if (rexeced_flag || inetd_flag)
1065 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1066 fatal("sshd re-exec requires execution with an absolute path");
1068 closefrom(REEXEC_MIN_FREE_FD);
1070 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1072 SSLeay_add_all_algorithms();
1075 * Force logging to stderr until we have loaded the private host
1076 * key (unless started from inetd)
1078 log_init(__progname,
1079 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1080 SYSLOG_LEVEL_INFO : options.log_level,
1081 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1082 SYSLOG_FACILITY_AUTH : options.log_facility,
1083 log_stderr || !inetd_flag);
1086 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1087 * root's environment
1089 if (getenv("KRB5CCNAME") != NULL)
1090 unsetenv("KRB5CCNAME");
1093 /* Cray can define user privs drop all privs now!
1094 * Not needed on PRIV_SU systems!
1099 sensitive_data.server_key = NULL;
1100 sensitive_data.ssh1_host_key = NULL;
1101 sensitive_data.have_ssh1_key = 0;
1102 sensitive_data.have_ssh2_key = 0;
1104 /* Fetch our configuration */
1107 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1109 load_server_config(config_file_name, &cfg);
1111 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1112 &cfg, NULL, NULL, NULL);
1116 /* Fill in default values for those options not explicitly set. */
1117 fill_default_server_options(&options);
1119 /* set default channel AF */
1120 channel_set_af(options.address_family);
1122 /* Check that there are no remaining arguments. */
1124 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1128 debug("sshd version %.100s", SSH_RELEASE);
1130 /* load private host keys */
1131 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1133 for (i = 0; i < options.num_host_key_files; i++)
1134 sensitive_data.host_keys[i] = NULL;
1136 for (i = 0; i < options.num_host_key_files; i++) {
1137 key = key_load_private(options.host_key_files[i], "", NULL);
1138 sensitive_data.host_keys[i] = key;
1140 error("Could not load host key: %s",
1141 options.host_key_files[i]);
1142 sensitive_data.host_keys[i] = NULL;
1145 switch (key->type) {
1147 sensitive_data.ssh1_host_key = key;
1148 sensitive_data.have_ssh1_key = 1;
1152 sensitive_data.have_ssh2_key = 1;
1155 debug("private host key: #%d type %d %s", i, key->type,
1158 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1159 logit("Disabling protocol version 1. Could not load host key");
1160 options.protocol &= ~SSH_PROTO_1;
1162 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1163 logit("Disabling protocol version 2. Could not load host key");
1164 options.protocol &= ~SSH_PROTO_2;
1166 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1167 logit("sshd: no hostkeys available -- exiting.");
1171 /* Check certain values for sanity. */
1172 if (options.protocol & SSH_PROTO_1) {
1173 if (options.server_key_bits < 512 ||
1174 options.server_key_bits > 32768) {
1175 fprintf(stderr, "Bad server key size.\n");
1179 * Check that server and host key lengths differ sufficiently. This
1180 * is necessary to make double encryption work with rsaref. Oh, I
1181 * hate software patents. I dont know if this can go? Niels
1183 if (options.server_key_bits >
1184 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1185 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1186 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1187 SSH_KEY_BITS_RESERVED) {
1188 options.server_key_bits =
1189 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1190 SSH_KEY_BITS_RESERVED;
1191 debug("Forcing server key to %d bits to make it differ from host key.",
1192 options.server_key_bits);
1199 if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1200 fatal("Privilege separation user %s does not exist",
1202 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1203 (S_ISDIR(st.st_mode) == 0))
1204 fatal("Missing privilege separation directory: %s",
1205 _PATH_PRIVSEP_CHROOT_DIR);
1208 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1209 (st.st_uid != getuid () ||
1210 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1212 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1214 fatal("%s must be owned by root and not group or "
1215 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1218 /* Configuration looks good, so exit if in test mode. */
1223 * Clear out any supplemental groups we may have inherited. This
1224 * prevents inadvertent creation of files with bad modes (in the
1225 * portable version at least, it's certainly possible for PAM
1226 * to create a file, and we can't control the code in every
1227 * module which might be used).
1229 if (setgroups(0, NULL) < 0)
1230 debug("setgroups() failed: %.200s", strerror(errno));
1233 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1234 for (i = 0; i < rexec_argc; i++) {
1235 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1236 rexec_argv[i] = saved_argv[i];
1238 rexec_argv[rexec_argc] = "-R";
1239 rexec_argv[rexec_argc + 1] = NULL;
1242 /* Initialize the log (it is reinitialized below in case we forked). */
1243 if (debug_flag && (!inetd_flag || rexeced_flag))
1245 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1248 * If not in debugging mode, and not started from inetd, disconnect
1249 * from the controlling terminal, and fork. The original process
1252 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1255 #endif /* TIOCNOTTY */
1256 if (daemon(0, 0) < 0)
1257 fatal("daemon() failed: %.200s", strerror(errno));
1259 /* Disconnect from the controlling tty. */
1261 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1263 (void) ioctl(fd, TIOCNOTTY, NULL);
1266 #endif /* TIOCNOTTY */
1268 /* Reinitialize the log (because of the fork above). */
1269 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1271 /* Initialize the random number generator. */
1274 /* Chdir to the root directory so that the current disk can be
1275 unmounted if desired. */
1278 /* ignore SIGPIPE */
1279 signal(SIGPIPE, SIG_IGN);
1281 /* Start listening for a socket, unless started from inetd. */
1287 close(REEXEC_CONFIG_PASS_FD);
1288 sock_in = sock_out = dup(STDIN_FILENO);
1290 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1291 close(REEXEC_STARTUP_PIPE_FD);
1294 sock_in = dup(STDIN_FILENO);
1295 sock_out = dup(STDOUT_FILENO);
1298 * We intentionally do not close the descriptors 0, 1, and 2
1299 * as our code for setting the descriptors won't work if
1300 * ttyfd happens to be one of those.
1302 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1303 dup2(fd, STDIN_FILENO);
1304 dup2(fd, STDOUT_FILENO);
1305 if (fd > STDOUT_FILENO)
1308 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1309 if ((options.protocol & SSH_PROTO_1) &&
1310 sensitive_data.server_key == NULL)
1311 generate_ephemeral_server_key();
1313 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1314 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1316 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1317 fatal("Too many listen sockets. "
1318 "Enlarge MAX_LISTEN_SOCKS");
1319 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1320 ntop, sizeof(ntop), strport, sizeof(strport),
1321 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1322 error("getnameinfo failed: %.100s",
1323 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1327 /* Create socket for listening. */
1328 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1330 if (listen_sock < 0) {
1331 /* kernel may not support ipv6 */
1332 verbose("socket: %.100s", strerror(errno));
1335 if (set_nonblock(listen_sock) == -1) {
1340 * Set socket options.
1341 * Allow local port reuse in TIME_WAIT.
1343 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1344 &on, sizeof(on)) == -1)
1345 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1347 debug("Bind to port %s on %s.", strport, ntop);
1349 /* Bind the socket to the desired port. */
1350 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1352 error("Bind to port %s on %s failed: %.200s.",
1353 strport, ntop, strerror(errno));
1357 listen_socks[num_listen_socks] = listen_sock;
1360 /* Start listening on the port. */
1361 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1362 fatal("listen on [%s]:%s: %.100s",
1363 ntop, strport, strerror(errno));
1364 logit("Server listening on %s port %s.", ntop, strport);
1366 freeaddrinfo(options.listen_addrs);
1368 if (!num_listen_socks)
1369 fatal("Cannot bind any address.");
1371 if (options.protocol & SSH_PROTO_1)
1372 generate_ephemeral_server_key();
1375 * Arrange to restart on SIGHUP. The handler needs
1378 signal(SIGHUP, sighup_handler);
1380 signal(SIGTERM, sigterm_handler);
1381 signal(SIGQUIT, sigterm_handler);
1383 /* Arrange SIGCHLD to be caught. */
1384 signal(SIGCHLD, main_sigchld_handler);
1386 /* Write out the pid file after the sigterm handler is setup */
1389 * Record our pid in /var/run/sshd.pid to make it
1390 * easier to kill the correct sshd. We don't want to
1391 * do this before the bind above because the bind will
1392 * fail if there already is a daemon, and this will
1393 * overwrite any old pid in the file.
1395 f = fopen(options.pid_file, "wb");
1397 error("Couldn't create pid file \"%s\": %s",
1398 options.pid_file, strerror(errno));
1400 fprintf(f, "%ld\n", (long) getpid());
1405 /* setup fd set for listen */
1408 for (i = 0; i < num_listen_socks; i++)
1409 if (listen_socks[i] > maxfd)
1410 maxfd = listen_socks[i];
1411 /* pipes connected to unauthenticated childs */
1412 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1413 for (i = 0; i < options.max_startups; i++)
1414 startup_pipes[i] = -1;
1417 * Stay listening for connections until the system crashes or
1418 * the daemon is killed with a signal.
1421 if (received_sighup)
1425 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1428 for (i = 0; i < num_listen_socks; i++)
1429 FD_SET(listen_socks[i], fdset);
1430 for (i = 0; i < options.max_startups; i++)
1431 if (startup_pipes[i] != -1)
1432 FD_SET(startup_pipes[i], fdset);
1434 /* Wait in select until there is a connection. */
1435 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1436 if (ret < 0 && errno != EINTR)
1437 error("select: %.100s", strerror(errno));
1438 if (received_sigterm) {
1439 logit("Received signal %d; terminating.",
1440 (int) received_sigterm);
1441 close_listen_socks();
1442 unlink(options.pid_file);
1445 if (key_used && key_do_regen) {
1446 generate_ephemeral_server_key();
1453 for (i = 0; i < options.max_startups; i++)
1454 if (startup_pipes[i] != -1 &&
1455 FD_ISSET(startup_pipes[i], fdset)) {
1457 * the read end of the pipe is ready
1458 * if the child has closed the pipe
1459 * after successful authentication
1460 * or if the child has died
1462 close(startup_pipes[i]);
1463 startup_pipes[i] = -1;
1466 for (i = 0; i < num_listen_socks; i++) {
1467 if (!FD_ISSET(listen_socks[i], fdset))
1469 fromlen = sizeof(from);
1470 newsock = accept(listen_socks[i],
1471 (struct sockaddr *)&from, &fromlen);
1473 if (errno != EINTR && errno != EWOULDBLOCK)
1474 error("accept: %.100s", strerror(errno));
1477 if (unset_nonblock(newsock) == -1) {
1481 if (drop_connection(startups) == 1) {
1482 debug("drop connection #%d", startups);
1486 if (pipe(startup_p) == -1) {
1491 if (rexec_flag && socketpair(AF_UNIX,
1492 SOCK_STREAM, 0, config_s) == -1) {
1493 error("reexec socketpair: %s",
1496 close(startup_p[0]);
1497 close(startup_p[1]);
1501 for (j = 0; j < options.max_startups; j++)
1502 if (startup_pipes[j] == -1) {
1503 startup_pipes[j] = startup_p[0];
1504 if (maxfd < startup_p[0])
1505 maxfd = startup_p[0];
1511 * Got connection. Fork a child to handle it, unless
1512 * we are in debugging mode.
1516 * In debugging mode. Close the listening
1517 * socket, and start processing the
1518 * connection without forking.
1520 debug("Server will not fork when running in debugging mode.");
1521 close_listen_socks();
1524 close(startup_p[0]);
1525 close(startup_p[1]);
1529 send_rexec_state(config_s[0],
1536 * Normal production daemon. Fork, and have
1537 * the child process the connection. The
1538 * parent continues listening.
1540 if ((pid = fork()) == 0) {
1542 * Child. Close the listening and
1543 * max_startup sockets. Start using
1544 * the accepted socket. Reinitialize
1545 * logging (since our pid has changed).
1546 * We break out of the loop to handle
1549 startup_pipe = startup_p[1];
1550 close_startup_pipes();
1551 close_listen_socks();
1554 log_init(__progname,
1556 options.log_facility,
1564 /* Parent. Stay in the loop. */
1566 error("fork: %.100s", strerror(errno));
1568 debug("Forked child %ld.", (long)pid);
1570 close(startup_p[1]);
1573 send_rexec_state(config_s[0], &cfg);
1579 * Mark that the key has been used (it
1580 * was "given" to the child).
1582 if ((options.protocol & SSH_PROTO_1) &&
1584 /* Schedule server key regeneration alarm. */
1585 signal(SIGALRM, key_regeneration_alarm);
1586 alarm(options.key_regeneration_time);
1593 /* child process check (or debug mode) */
1594 if (num_listen_socks < 0)
1599 /* This is the child processing a new connection. */
1600 setproctitle("%s", "[accepted]");
1603 * Create a new session and process group since the 4.4BSD
1604 * setlogin() affects the entire process group. We don't
1605 * want the child to be able to affect the parent.
1607 #if !defined(SSHD_ACQUIRES_CTTY)
1609 * If setsid is called, on some platforms sshd will later acquire a
1610 * controlling terminal which will result in "could not set
1611 * controlling tty" errors.
1613 if (!debug_flag && !inetd_flag && setsid() < 0)
1614 error("setsid: %.100s", strerror(errno));
1620 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1621 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1622 dup2(newsock, STDIN_FILENO);
1623 dup2(STDIN_FILENO, STDOUT_FILENO);
1624 if (startup_pipe == -1)
1625 close(REEXEC_STARTUP_PIPE_FD);
1627 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1629 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1631 if (startup_pipe != -1)
1632 close(startup_pipe);
1634 execv(rexec_argv[0], rexec_argv);
1636 /* Reexec has failed, fall back and continue */
1637 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1638 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1639 log_init(__progname, options.log_level,
1640 options.log_facility, log_stderr);
1643 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1645 close(REEXEC_CONFIG_PASS_FD);
1646 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1647 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1648 dup2(fd, STDIN_FILENO);
1649 dup2(fd, STDOUT_FILENO);
1650 if (fd > STDERR_FILENO)
1653 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1654 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1658 * Disable the key regeneration alarm. We will not regenerate the
1659 * key since we are no longer in a position to give it to anyone. We
1660 * will not restart on SIGHUP since it no longer makes sense.
1663 signal(SIGALRM, SIG_DFL);
1664 signal(SIGHUP, SIG_DFL);
1665 signal(SIGTERM, SIG_DFL);
1666 signal(SIGQUIT, SIG_DFL);
1667 signal(SIGCHLD, SIG_DFL);
1668 signal(SIGINT, SIG_DFL);
1671 * Register our connection. This turns encryption off because we do
1674 packet_set_connection(sock_in, sock_out);
1675 packet_set_server();
1677 /* Set SO_KEEPALIVE if requested. */
1678 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1679 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1680 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1682 if ((remote_port = get_remote_port()) < 0) {
1683 debug("get_remote_port failed");
1688 * We use get_canonical_hostname with usedns = 0 instead of
1689 * get_remote_ipaddr here so IP options will be checked.
1691 (void) get_canonical_hostname(0);
1693 * The rest of the code depends on the fact that
1694 * get_remote_ipaddr() caches the remote ip, even if
1695 * the socket goes away.
1697 remote_ip = get_remote_ipaddr();
1699 #ifdef SSH_AUDIT_EVENTS
1700 audit_connection_from(remote_ip, remote_port);
1703 /* Check whether logins are denied from this host. */
1704 if (packet_connection_is_on_socket()) {
1705 struct request_info req;
1707 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1710 if (!hosts_access(&req)) {
1711 debug("Connection refused by tcp wrapper");
1714 fatal("libwrap refuse returns");
1717 #endif /* LIBWRAP */
1719 /* Log the connection. */
1720 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1723 * We don't want to listen forever unless the other side
1724 * successfully authenticates itself. So we set up an alarm which is
1725 * cleared after successful authentication. A limit of zero
1726 * indicates no limit. Note that we don't set the alarm in debugging
1727 * mode; it is just annoying to have the server exit just when you
1728 * are about to discover the bug.
1730 signal(SIGALRM, grace_alarm_handler);
1732 alarm(options.login_grace_time);
1734 sshd_exchange_identification(sock_in, sock_out);
1736 packet_set_nonblocking();
1738 /* allocate authentication context */
1739 authctxt = xcalloc(1, sizeof(*authctxt));
1741 authctxt->loginmsg = &loginmsg;
1743 /* XXX global for cleanup, access from other modules */
1744 the_authctxt = authctxt;
1746 /* prepare buffer to collect messages to display to user after login */
1747 buffer_init(&loginmsg);
1750 if (privsep_preauth(authctxt) == 1)
1753 /* perform the key exchange */
1754 /* authenticate user and start session */
1757 do_authentication2(authctxt);
1760 do_authentication(authctxt);
1763 * If we use privilege separation, the unprivileged child transfers
1764 * the current keystate and exits
1767 mm_send_keystate(pmonitor);
1773 * Cancel the alarm we set to limit the time taken for
1777 signal(SIGALRM, SIG_DFL);
1778 if (startup_pipe != -1) {
1779 close(startup_pipe);
1783 #ifdef SSH_AUDIT_EVENTS
1784 audit_event(SSH_AUTH_SUCCESS);
1788 * In privilege separation, we fork another child and prepare
1789 * file descriptor passing.
1792 privsep_postauth(authctxt);
1793 /* the monitor process [priv] will not return */
1795 destroy_sensitive_data();
1798 /* Start session. */
1799 do_authenticated(authctxt);
1801 /* The connection has been terminated. */
1802 verbose("Closing connection to %.100s", remote_ip);
1805 if (options.use_pam)
1807 #endif /* USE_PAM */
1809 #ifdef SSH_AUDIT_EVENTS
1810 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1822 * Decrypt session_key_int using our private server key and private host key
1823 * (key with larger modulus first).
1826 ssh1_session_key(BIGNUM *session_key_int)
1830 if (BN_cmp(sensitive_data.server_key->rsa->n,
1831 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1832 /* Server key has bigger modulus. */
1833 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1834 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1835 SSH_KEY_BITS_RESERVED) {
1836 fatal("do_connection: %s: "
1837 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1838 get_remote_ipaddr(),
1839 BN_num_bits(sensitive_data.server_key->rsa->n),
1840 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1841 SSH_KEY_BITS_RESERVED);
1843 if (rsa_private_decrypt(session_key_int, session_key_int,
1844 sensitive_data.server_key->rsa) <= 0)
1846 if (rsa_private_decrypt(session_key_int, session_key_int,
1847 sensitive_data.ssh1_host_key->rsa) <= 0)
1850 /* Host key has bigger modulus (or they are equal). */
1851 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1852 BN_num_bits(sensitive_data.server_key->rsa->n) +
1853 SSH_KEY_BITS_RESERVED) {
1854 fatal("do_connection: %s: "
1855 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1856 get_remote_ipaddr(),
1857 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1858 BN_num_bits(sensitive_data.server_key->rsa->n),
1859 SSH_KEY_BITS_RESERVED);
1861 if (rsa_private_decrypt(session_key_int, session_key_int,
1862 sensitive_data.ssh1_host_key->rsa) < 0)
1864 if (rsa_private_decrypt(session_key_int, session_key_int,
1865 sensitive_data.server_key->rsa) < 0)
1878 BIGNUM *session_key_int;
1879 u_char session_key[SSH_SESSION_KEY_LENGTH];
1881 u_int cipher_type, auth_mask, protocol_flags;
1885 * Generate check bytes that the client must send back in the user
1886 * packet in order for it to be accepted; this is used to defy ip
1887 * spoofing attacks. Note that this only works against somebody
1888 * doing IP spoofing from a remote machine; any machine on the local
1889 * network can still see outgoing packets and catch the random
1890 * cookie. This only affects rhosts authentication, and this is one
1891 * of the reasons why it is inherently insecure.
1893 for (i = 0; i < 8; i++) {
1896 cookie[i] = rnd & 0xff;
1901 * Send our public key. We include in the packet 64 bits of random
1902 * data that must be matched in the reply in order to prevent IP
1905 packet_start(SSH_SMSG_PUBLIC_KEY);
1906 for (i = 0; i < 8; i++)
1907 packet_put_char(cookie[i]);
1909 /* Store our public server RSA key. */
1910 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1911 packet_put_bignum(sensitive_data.server_key->rsa->e);
1912 packet_put_bignum(sensitive_data.server_key->rsa->n);
1914 /* Store our public host RSA key. */
1915 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1916 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1917 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1919 /* Put protocol flags. */
1920 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1922 /* Declare which ciphers we support. */
1923 packet_put_int(cipher_mask_ssh1(0));
1925 /* Declare supported authentication types. */
1927 if (options.rhosts_rsa_authentication)
1928 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1929 if (options.rsa_authentication)
1930 auth_mask |= 1 << SSH_AUTH_RSA;
1931 if (options.challenge_response_authentication == 1)
1932 auth_mask |= 1 << SSH_AUTH_TIS;
1933 if (options.password_authentication)
1934 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1935 packet_put_int(auth_mask);
1937 /* Send the packet and wait for it to be sent. */
1939 packet_write_wait();
1941 debug("Sent %d bit server key and %d bit host key.",
1942 BN_num_bits(sensitive_data.server_key->rsa->n),
1943 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1945 /* Read clients reply (cipher type and session key). */
1946 packet_read_expect(SSH_CMSG_SESSION_KEY);
1948 /* Get cipher type and check whether we accept this. */
1949 cipher_type = packet_get_char();
1951 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1952 packet_disconnect("Warning: client selects unsupported cipher.");
1954 /* Get check bytes from the packet. These must match those we
1955 sent earlier with the public key packet. */
1956 for (i = 0; i < 8; i++)
1957 if (cookie[i] != packet_get_char())
1958 packet_disconnect("IP Spoofing check bytes do not match.");
1960 debug("Encryption type: %.200s", cipher_name(cipher_type));
1962 /* Get the encrypted integer. */
1963 if ((session_key_int = BN_new()) == NULL)
1964 fatal("do_ssh1_kex: BN_new failed");
1965 packet_get_bignum(session_key_int);
1967 protocol_flags = packet_get_int();
1968 packet_set_protocol_flags(protocol_flags);
1971 /* Decrypt session_key_int using host/server keys */
1972 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1975 * Extract session key from the decrypted integer. The key is in the
1976 * least significant 256 bits of the integer; the first byte of the
1977 * key is in the highest bits.
1980 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1981 len = BN_num_bytes(session_key_int);
1982 if (len < 0 || (u_int)len > sizeof(session_key)) {
1983 error("do_connection: bad session key len from %s: "
1984 "session_key_int %d > sizeof(session_key) %lu",
1985 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1988 memset(session_key, 0, sizeof(session_key));
1989 BN_bn2bin(session_key_int,
1990 session_key + sizeof(session_key) - len);
1992 derive_ssh1_session_id(
1993 sensitive_data.ssh1_host_key->rsa->n,
1994 sensitive_data.server_key->rsa->n,
1995 cookie, session_id);
1997 * Xor the first 16 bytes of the session key with the
2000 for (i = 0; i < 16; i++)
2001 session_key[i] ^= session_id[i];
2005 int bytes = BN_num_bytes(session_key_int);
2006 u_char *buf = xmalloc(bytes);
2009 logit("do_connection: generating a fake encryption key");
2010 BN_bn2bin(session_key_int, buf);
2012 MD5_Update(&md, buf, bytes);
2013 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2014 MD5_Final(session_key, &md);
2016 MD5_Update(&md, session_key, 16);
2017 MD5_Update(&md, buf, bytes);
2018 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2019 MD5_Final(session_key + 16, &md);
2020 memset(buf, 0, bytes);
2022 for (i = 0; i < 16; i++)
2023 session_id[i] = session_key[i] ^ session_key[i + 16];
2025 /* Destroy the private and public keys. No longer. */
2026 destroy_sensitive_data();
2029 mm_ssh1_session_id(session_id);
2031 /* Destroy the decrypted integer. It is no longer needed. */
2032 BN_clear_free(session_key_int);
2034 /* Set the session key. From this on all communications will be encrypted. */
2035 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2037 /* Destroy our copy of the session key. It is no longer needed. */
2038 memset(session_key, 0, sizeof(session_key));
2040 debug("Received session key; encryption turned on.");
2042 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2043 packet_start(SSH_SMSG_SUCCESS);
2045 packet_write_wait();
2049 * SSH2 key exchange: diffie-hellman-group1-sha1
2056 if (options.ciphers != NULL) {
2057 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2058 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2060 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2061 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2062 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2063 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2065 if (options.macs != NULL) {
2066 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2067 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2069 if (options.compression == COMP_NONE) {
2070 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2071 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2072 } else if (options.compression == COMP_DELAYED) {
2073 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2074 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2077 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2079 /* start key exchange */
2080 kex = kex_setup(myproposal);
2081 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2082 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2083 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2084 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2086 kex->client_version_string=client_version_string;
2087 kex->server_version_string=server_version_string;
2088 kex->load_host_key=&get_hostkey_by_type;
2089 kex->host_key_index=&get_hostkey_index;
2093 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2095 session_id2 = kex->session_id;
2096 session_id2_len = kex->session_id_len;
2099 /* send 1st encrypted/maced/compressed message */
2100 packet_start(SSH2_MSG_IGNORE);
2101 packet_put_cstring("markus");
2103 packet_write_wait();
2108 /* server specific fatal cleanup */
2113 do_cleanup(the_authctxt);
2114 #ifdef SSH_AUDIT_EVENTS
2115 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2116 if (!use_privsep || mm_is_monitor())
2117 audit_event(SSH_CONNECTION_ABANDON);