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 1.307 2005/01/21 08:32:02 otto Exp $");
47 #include <openssl/dh.h>
48 #include <openssl/bn.h>
49 #include <openssl/md5.h>
50 #include <openssl/rand.h>
51 #ifdef HAVE_SECUREWARE
52 #include <sys/security.h>
73 #include "myproposal.h"
75 #include "pathnames.h"
84 #include "monitor_mm.h"
86 #include "monitor_wrap.h"
87 #include "monitor_fdpass.h"
92 int allow_severity = LOG_INFO;
93 int deny_severity = LOG_WARNING;
101 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
102 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
103 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
104 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
106 extern char *__progname;
108 /* Server configuration options. */
109 ServerOptions options;
111 /* Name of the server configuration file. */
112 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
115 * Debug mode flag. This can be set on the command line. If debug
116 * mode is enabled, extra debugging output will be sent to the system
117 * log, the daemon will not go to background, and will exit after processing
118 * the first connection.
122 /* Flag indicating that the daemon should only test the configuration and keys. */
125 /* Flag indicating that the daemon is being started from inetd. */
128 /* Flag indicating that sshd should not detach and become a daemon. */
129 int no_daemon_flag = 0;
131 /* debug goes to stderr unless inetd_flag is set */
134 /* Saved arguments to main(). */
139 int rexeced_flag = 0;
145 * The sockets that the server is listening; this is used in the SIGHUP
148 #define MAX_LISTEN_SOCKS 16
149 int listen_socks[MAX_LISTEN_SOCKS];
150 int num_listen_socks = 0;
153 * the client's version string, passed by sshd2 in compat mode. if != NULL,
154 * sshd will skip the version-number exchange
156 char *client_version_string = NULL;
157 char *server_version_string = NULL;
159 /* for rekeying XXX fixme */
163 * Any really sensitive data in the application is contained in this
164 * structure. The idea is that this structure could be locked into memory so
165 * that the pages do not get written into swap. However, there are some
166 * problems. The private key contains BIGNUMs, and we do not (in principle)
167 * have access to the internals of them, and locking just the structure is
168 * not very useful. Currently, memory locking is not implemented.
171 Key *server_key; /* ephemeral server key */
172 Key *ssh1_host_key; /* ssh1 host key */
173 Key **host_keys; /* all private host keys */
176 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
180 * Flag indicating whether the RSA server key needs to be regenerated.
181 * Is set in the SIGALRM handler and cleared when the key is regenerated.
183 static volatile sig_atomic_t key_do_regen = 0;
185 /* This is set to true when a signal is received. */
186 static volatile sig_atomic_t received_sighup = 0;
187 static volatile sig_atomic_t received_sigterm = 0;
189 /* session identifier, used by RSA-auth */
190 u_char session_id[16];
193 u_char *session_id2 = NULL;
194 u_int session_id2_len = 0;
196 /* record remote hostname or ip */
197 u_int utmp_len = MAXHOSTNAMELEN;
199 /* options.max_startup sized array of fd ints */
200 int *startup_pipes = NULL;
201 int startup_pipe; /* in child */
203 /* variables used for privilege separation */
205 struct monitor *pmonitor = NULL;
207 /* global authentication context */
208 Authctxt *the_authctxt = NULL;
210 /* message to be displayed after login */
213 /* Prototypes for various functions defined later in this file. */
214 void destroy_sensitive_data(void);
215 void demote_sensitive_data(void);
217 static void do_ssh1_kex(void);
218 static void do_ssh2_kex(void);
221 * Close all listening sockets
224 close_listen_socks(void)
228 for (i = 0; i < num_listen_socks; i++)
229 close(listen_socks[i]);
230 num_listen_socks = -1;
234 close_startup_pipes(void)
239 for (i = 0; i < options.max_startups; i++)
240 if (startup_pipes[i] != -1)
241 close(startup_pipes[i]);
245 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
246 * the effect is to reread the configuration file (and to regenerate
250 sighup_handler(int sig)
252 int save_errno = errno;
255 signal(SIGHUP, sighup_handler);
260 * Called from the main program after receiving SIGHUP.
261 * Restarts the server.
266 logit("Received SIGHUP; restarting.");
267 close_listen_socks();
268 close_startup_pipes();
269 execv(saved_argv[0], saved_argv);
270 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
276 * Generic signal handler for terminating signals in the master daemon.
279 sigterm_handler(int sig)
281 received_sigterm = sig;
285 * SIGCHLD handler. This is called whenever a child dies. This will then
286 * reap any zombies left by exited children.
289 main_sigchld_handler(int sig)
291 int save_errno = errno;
295 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
296 (pid < 0 && errno == EINTR))
299 signal(SIGCHLD, main_sigchld_handler);
304 * Signal handler for the alarm after the login grace period has expired.
307 grace_alarm_handler(int sig)
309 /* XXX no idea how fix this signal handler */
311 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
312 kill(pmonitor->m_pid, SIGALRM);
314 /* Log error and exit. */
315 fatal("Timeout before authentication for %s", get_remote_ipaddr());
319 * Signal handler for the key regeneration alarm. Note that this
320 * alarm only occurs in the daemon waiting for connections, and it does not
321 * do anything with the private key or random state before forking.
322 * Thus there should be no concurrency control/asynchronous execution
326 generate_ephemeral_server_key(void)
331 verbose("Generating %s%d bit RSA key.",
332 sensitive_data.server_key ? "new " : "", options.server_key_bits);
333 if (sensitive_data.server_key != NULL)
334 key_free(sensitive_data.server_key);
335 sensitive_data.server_key = key_generate(KEY_RSA1,
336 options.server_key_bits);
337 verbose("RSA key generation complete.");
339 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
342 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
349 key_regeneration_alarm(int sig)
351 int save_errno = errno;
353 signal(SIGALRM, SIG_DFL);
359 sshd_exchange_identification(int sock_in, int sock_out)
362 int remote_major, remote_minor;
365 char buf[256]; /* Must not be larger than remote_version. */
366 char remote_version[256]; /* Must be at least as big as buf. */
368 if ((options.protocol & SSH_PROTO_1) &&
369 (options.protocol & SSH_PROTO_2)) {
370 major = PROTOCOL_MAJOR_1;
372 } else if (options.protocol & SSH_PROTO_2) {
373 major = PROTOCOL_MAJOR_2;
374 minor = PROTOCOL_MINOR_2;
376 major = PROTOCOL_MAJOR_1;
377 minor = PROTOCOL_MINOR_1;
379 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
380 server_version_string = xstrdup(buf);
382 /* Send our protocol version identification. */
383 if (atomicio(vwrite, sock_out, server_version_string,
384 strlen(server_version_string))
385 != strlen(server_version_string)) {
386 logit("Could not write ident string to %s", get_remote_ipaddr());
390 /* Read other sides version identification. */
391 memset(buf, 0, sizeof(buf));
392 for (i = 0; i < sizeof(buf) - 1; i++) {
393 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
394 logit("Did not receive identification string from %s",
395 get_remote_ipaddr());
398 if (buf[i] == '\r') {
400 /* Kludge for F-Secure Macintosh < 1.0.2 */
402 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
406 if (buf[i] == '\n') {
411 buf[sizeof(buf) - 1] = 0;
412 client_version_string = xstrdup(buf);
415 * Check that the versions match. In future this might accept
416 * several versions and set appropriate flags to handle them.
418 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
419 &remote_major, &remote_minor, remote_version) != 3) {
420 s = "Protocol mismatch.\n";
421 (void) atomicio(vwrite, sock_out, s, strlen(s));
424 logit("Bad protocol version identification '%.100s' from %s",
425 client_version_string, get_remote_ipaddr());
428 debug("Client protocol version %d.%d; client software version %.100s",
429 remote_major, remote_minor, remote_version);
431 compat_datafellows(remote_version);
433 if (datafellows & SSH_BUG_PROBE) {
434 logit("probed from %s with %s. Don't panic.",
435 get_remote_ipaddr(), client_version_string);
439 if (datafellows & SSH_BUG_SCANNER) {
440 logit("scanned from %s with %s. Don't panic.",
441 get_remote_ipaddr(), client_version_string);
446 switch (remote_major) {
448 if (remote_minor == 99) {
449 if (options.protocol & SSH_PROTO_2)
455 if (!(options.protocol & SSH_PROTO_1)) {
459 if (remote_minor < 3) {
460 packet_disconnect("Your ssh version is too old and "
461 "is no longer supported. Please install a newer version.");
462 } else if (remote_minor == 3) {
463 /* note that this disables agent-forwarding */
468 if (options.protocol & SSH_PROTO_2) {
477 chop(server_version_string);
478 debug("Local version string %.200s", server_version_string);
481 s = "Protocol major versions differ.\n";
482 (void) atomicio(vwrite, sock_out, s, strlen(s));
485 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
487 server_version_string, client_version_string);
492 /* Destroy the host and server keys. They will no longer be needed. */
494 destroy_sensitive_data(void)
498 if (sensitive_data.server_key) {
499 key_free(sensitive_data.server_key);
500 sensitive_data.server_key = NULL;
502 for (i = 0; i < options.num_host_key_files; i++) {
503 if (sensitive_data.host_keys[i]) {
504 key_free(sensitive_data.host_keys[i]);
505 sensitive_data.host_keys[i] = NULL;
508 sensitive_data.ssh1_host_key = NULL;
509 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
512 /* Demote private to public keys for network child */
514 demote_sensitive_data(void)
519 if (sensitive_data.server_key) {
520 tmp = key_demote(sensitive_data.server_key);
521 key_free(sensitive_data.server_key);
522 sensitive_data.server_key = tmp;
525 for (i = 0; i < options.num_host_key_files; i++) {
526 if (sensitive_data.host_keys[i]) {
527 tmp = key_demote(sensitive_data.host_keys[i]);
528 key_free(sensitive_data.host_keys[i]);
529 sensitive_data.host_keys[i] = tmp;
530 if (tmp->type == KEY_RSA1)
531 sensitive_data.ssh1_host_key = tmp;
535 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
539 privsep_preauth_child(void)
546 /* Enable challenge-response authentication for privilege separation */
547 privsep_challenge_enable();
549 for (i = 0; i < 256; i++)
550 rnd[i] = arc4random();
551 RAND_seed(rnd, sizeof(rnd));
553 /* Demote the private keys to public keys. */
554 demote_sensitive_data();
556 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
557 fatal("Privilege separation user %s does not exist",
559 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
562 /* Change our root directory */
563 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
564 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
566 if (chdir("/") == -1)
567 fatal("chdir(\"/\"): %s", strerror(errno));
569 /* Drop our privileges */
570 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
573 /* XXX not ready, too heavy after chroot */
574 do_setusercontext(pw);
576 gidset[0] = pw->pw_gid;
577 if (setgroups(1, gidset) < 0)
578 fatal("setgroups: %.100s", strerror(errno));
579 permanently_set_uid(pw);
584 privsep_preauth(Authctxt *authctxt)
589 /* Set up unprivileged child process to deal with network data */
590 pmonitor = monitor_init();
591 /* Store a pointer to the kex for later rekeying */
592 pmonitor->m_pkex = &xxx_kex;
596 fatal("fork of unprivileged child failed");
597 } else if (pid != 0) {
598 debug2("Network child is on pid %ld", (long)pid);
600 close(pmonitor->m_recvfd);
601 pmonitor->m_pid = pid;
602 monitor_child_preauth(authctxt, pmonitor);
603 close(pmonitor->m_sendfd);
606 monitor_sync(pmonitor);
608 /* Wait for the child's exit status */
609 while (waitpid(pid, &status, 0) < 0)
616 close(pmonitor->m_sendfd);
618 /* Demote the child */
619 if (getuid() == 0 || geteuid() == 0)
620 privsep_preauth_child();
621 setproctitle("%s", "[net]");
627 privsep_postauth(Authctxt *authctxt)
629 #ifdef DISABLE_FD_PASSING
632 if (authctxt->pw->pw_uid == 0 || options.use_login) {
634 /* File descriptor passing is broken or root login */
635 monitor_apply_keystate(pmonitor);
640 /* Authentication complete */
642 if (startup_pipe != -1) {
647 /* New socket pair */
648 monitor_reinit(pmonitor);
650 pmonitor->m_pid = fork();
651 if (pmonitor->m_pid == -1)
652 fatal("fork of unprivileged child failed");
653 else if (pmonitor->m_pid != 0) {
654 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
655 close(pmonitor->m_recvfd);
656 buffer_clear(&loginmsg);
657 monitor_child_postauth(pmonitor);
663 close(pmonitor->m_sendfd);
665 /* Demote the private keys to public keys. */
666 demote_sensitive_data();
668 /* Drop privileges */
669 do_setusercontext(authctxt->pw);
671 /* It is safe now to apply the key state */
672 monitor_apply_keystate(pmonitor);
676 list_hostkey_types(void)
684 for (i = 0; i < options.num_host_key_files; i++) {
685 Key *key = sensitive_data.host_keys[i];
691 if (buffer_len(&b) > 0)
692 buffer_append(&b, ",", 1);
693 p = key_ssh_name(key);
694 buffer_append(&b, p, strlen(p));
698 buffer_append(&b, "\0", 1);
699 ret = xstrdup(buffer_ptr(&b));
701 debug("list_hostkey_types: %s", ret);
706 get_hostkey_by_type(int type)
710 for (i = 0; i < options.num_host_key_files; i++) {
711 Key *key = sensitive_data.host_keys[i];
712 if (key != NULL && key->type == type)
719 get_hostkey_by_index(int ind)
721 if (ind < 0 || ind >= options.num_host_key_files)
723 return (sensitive_data.host_keys[ind]);
727 get_hostkey_index(Key *key)
731 for (i = 0; i < options.num_host_key_files; i++) {
732 if (key == sensitive_data.host_keys[i])
739 * returns 1 if connection should be dropped, 0 otherwise.
740 * dropping starts at connection #max_startups_begin with a probability
741 * of (max_startups_rate/100). the probability increases linearly until
742 * all connections are dropped for startups > max_startups
745 drop_connection(int startups)
749 if (startups < options.max_startups_begin)
751 if (startups >= options.max_startups)
753 if (options.max_startups_rate == 100)
756 p = 100 - options.max_startups_rate;
757 p *= startups - options.max_startups_begin;
758 p /= options.max_startups - options.max_startups_begin;
759 p += options.max_startups_rate;
760 r = arc4random() % 100;
762 debug("drop_connection: p %d, r %d", p, r);
763 return (r < p) ? 1 : 0;
769 fprintf(stderr, "%s, %s\n",
770 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
772 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
773 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
779 send_rexec_state(int fd, Buffer *conf)
783 debug3("%s: entering fd = %d config len %d", __func__, fd,
787 * Protocol from reexec master to child:
788 * string configuration
789 * u_int ephemeral_key_follows
790 * bignum e (only if ephemeral_key_follows == 1)
798 buffer_put_cstring(&m, buffer_ptr(conf));
800 if (sensitive_data.server_key != NULL &&
801 sensitive_data.server_key->type == KEY_RSA1) {
802 buffer_put_int(&m, 1);
803 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
804 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
805 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
806 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
807 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
808 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
810 buffer_put_int(&m, 0);
812 if (ssh_msg_send(fd, 0, &m) == -1)
813 fatal("%s: ssh_msg_send failed", __func__);
817 debug3("%s: done", __func__);
821 recv_rexec_state(int fd, Buffer *conf)
827 debug3("%s: entering fd = %d", __func__, fd);
831 if (ssh_msg_recv(fd, &m) == -1)
832 fatal("%s: ssh_msg_recv failed", __func__);
833 if (buffer_get_char(&m) != 0)
834 fatal("%s: rexec version mismatch", __func__);
836 cp = buffer_get_string(&m, &len);
838 buffer_append(conf, cp, len + 1);
841 if (buffer_get_int(&m)) {
842 if (sensitive_data.server_key != NULL)
843 key_free(sensitive_data.server_key);
844 sensitive_data.server_key = key_new_private(KEY_RSA1);
845 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
846 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
847 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
848 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
849 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
850 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
851 rsa_generate_additional_parameters(
852 sensitive_data.server_key->rsa);
856 debug3("%s: done", __func__);
860 * Main program for the daemon.
863 main(int ac, char **av)
867 int opt, j, i, fdsetsz, on = 1;
868 int sock_in = -1, sock_out = -1, newsock = -1;
872 struct sockaddr_storage from;
873 const char *remote_ip;
877 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
879 int listen_sock, maxfd;
880 int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
884 int ret, key_used = 0;
887 #ifdef HAVE_SECUREWARE
888 (void)set_auth_parameters(ac, av);
890 __progname = ssh_get_progname(av[0]);
893 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
896 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
897 for (i = 0; i < ac; i++)
898 saved_argv[i] = xstrdup(av[i]);
899 saved_argv[i] = NULL;
901 #ifndef HAVE_SETPROCTITLE
902 /* Prepare for later setproctitle emulation */
903 compat_init_setproctitle(ac, av);
907 if (geteuid() == 0 && setgroups(0, NULL) == -1)
908 debug("setgroups(): %.200s", strerror(errno));
910 /* Initialize configuration options to their default values. */
911 initialize_server_options(&options);
913 /* Parse command-line arguments. */
914 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
917 options.address_family = AF_INET;
920 options.address_family = AF_INET6;
923 config_file_name = optarg;
926 if (debug_flag == 0) {
928 options.log_level = SYSLOG_LEVEL_DEBUG1;
929 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
952 options.log_level = SYSLOG_LEVEL_QUIET;
955 options.server_key_bits = atoi(optarg);
958 options.ports_from_cmdline = 1;
959 if (options.num_ports >= MAX_PORTS) {
960 fprintf(stderr, "too many ports.\n");
963 options.ports[options.num_ports++] = a2port(optarg);
964 if (options.ports[options.num_ports-1] == 0) {
965 fprintf(stderr, "Bad port number.\n");
970 if ((options.login_grace_time = convtime(optarg)) == -1) {
971 fprintf(stderr, "Invalid login grace time.\n");
976 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
977 fprintf(stderr, "Invalid key regeneration interval.\n");
982 if (options.num_host_key_files >= MAX_HOSTKEYS) {
983 fprintf(stderr, "too many host keys.\n");
986 options.host_key_files[options.num_host_key_files++] = optarg;
992 utmp_len = atoi(optarg);
993 if (utmp_len > MAXHOSTNAMELEN) {
994 fprintf(stderr, "Invalid utmp length.\n");
999 line = xstrdup(optarg);
1000 if (process_server_config_line(&options, line,
1001 "command-line", 0) != 0)
1011 if (rexeced_flag || inetd_flag)
1013 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1014 fatal("sshd re-exec requires execution with an absolute path");
1016 closefrom(REEXEC_MIN_FREE_FD);
1018 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1020 SSLeay_add_all_algorithms();
1023 * Force logging to stderr until we have loaded the private host
1024 * key (unless started from inetd)
1026 log_init(__progname,
1027 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1028 SYSLOG_LEVEL_INFO : options.log_level,
1029 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1030 SYSLOG_FACILITY_AUTH : options.log_facility,
1031 log_stderr || !inetd_flag);
1035 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1036 * root's environment
1038 unsetenv("KRB5CCNAME");
1041 /* Cray can define user privs drop all privs now!
1042 * Not needed on PRIV_SU systems!
1049 sensitive_data.server_key = NULL;
1050 sensitive_data.ssh1_host_key = NULL;
1051 sensitive_data.have_ssh1_key = 0;
1052 sensitive_data.have_ssh2_key = 0;
1054 /* Fetch our configuration */
1057 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1059 load_server_config(config_file_name, &cfg);
1061 parse_server_config(&options,
1062 rexeced_flag ? "rexec" : config_file_name, &cfg);
1067 /* Fill in default values for those options not explicitly set. */
1068 fill_default_server_options(&options);
1070 /* set default channel AF */
1071 channel_set_af(options.address_family);
1073 /* Check that there are no remaining arguments. */
1075 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1079 debug("sshd version %.100s", SSH_RELEASE);
1081 /* load private host keys */
1082 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1084 for (i = 0; i < options.num_host_key_files; i++)
1085 sensitive_data.host_keys[i] = NULL;
1087 for (i = 0; i < options.num_host_key_files; i++) {
1088 key = key_load_private(options.host_key_files[i], "", NULL);
1089 sensitive_data.host_keys[i] = key;
1091 error("Could not load host key: %s",
1092 options.host_key_files[i]);
1093 sensitive_data.host_keys[i] = NULL;
1096 switch (key->type) {
1098 sensitive_data.ssh1_host_key = key;
1099 sensitive_data.have_ssh1_key = 1;
1103 sensitive_data.have_ssh2_key = 1;
1106 debug("private host key: #%d type %d %s", i, key->type,
1109 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1110 logit("Disabling protocol version 1. Could not load host key");
1111 options.protocol &= ~SSH_PROTO_1;
1113 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1114 logit("Disabling protocol version 2. Could not load host key");
1115 options.protocol &= ~SSH_PROTO_2;
1117 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1118 logit("sshd: no hostkeys available -- exiting.");
1122 /* Check certain values for sanity. */
1123 if (options.protocol & SSH_PROTO_1) {
1124 if (options.server_key_bits < 512 ||
1125 options.server_key_bits > 32768) {
1126 fprintf(stderr, "Bad server key size.\n");
1130 * Check that server and host key lengths differ sufficiently. This
1131 * is necessary to make double encryption work with rsaref. Oh, I
1132 * hate software patents. I dont know if this can go? Niels
1134 if (options.server_key_bits >
1135 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1136 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1137 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1138 SSH_KEY_BITS_RESERVED) {
1139 options.server_key_bits =
1140 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1141 SSH_KEY_BITS_RESERVED;
1142 debug("Forcing server key to %d bits to make it differ from host key.",
1143 options.server_key_bits);
1151 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1152 fatal("Privilege separation user %s does not exist",
1154 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1155 (S_ISDIR(st.st_mode) == 0))
1156 fatal("Missing privilege separation directory: %s",
1157 _PATH_PRIVSEP_CHROOT_DIR);
1160 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1161 (st.st_uid != getuid () ||
1162 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1164 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1166 fatal("%s must be owned by root and not group or "
1167 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1170 /* Configuration looks good, so exit if in test mode. */
1175 * Clear out any supplemental groups we may have inherited. This
1176 * prevents inadvertent creation of files with bad modes (in the
1177 * portable version at least, it's certainly possible for PAM
1178 * to create a file, and we can't control the code in every
1179 * module which might be used).
1181 if (setgroups(0, NULL) < 0)
1182 debug("setgroups() failed: %.200s", strerror(errno));
1185 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1186 for (i = 0; i < rexec_argc; i++) {
1187 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1188 rexec_argv[i] = saved_argv[i];
1190 rexec_argv[rexec_argc] = "-R";
1191 rexec_argv[rexec_argc + 1] = NULL;
1194 /* Initialize the log (it is reinitialized below in case we forked). */
1195 if (debug_flag && (!inetd_flag || rexeced_flag))
1197 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1200 * If not in debugging mode, and not started from inetd, disconnect
1201 * from the controlling terminal, and fork. The original process
1204 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1207 #endif /* TIOCNOTTY */
1208 if (daemon(0, 0) < 0)
1209 fatal("daemon() failed: %.200s", strerror(errno));
1211 /* Disconnect from the controlling tty. */
1213 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1215 (void) ioctl(fd, TIOCNOTTY, NULL);
1218 #endif /* TIOCNOTTY */
1220 /* Reinitialize the log (because of the fork above). */
1221 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1223 /* Initialize the random number generator. */
1226 /* Chdir to the root directory so that the current disk can be
1227 unmounted if desired. */
1230 /* ignore SIGPIPE */
1231 signal(SIGPIPE, SIG_IGN);
1233 /* Start listening for a socket, unless started from inetd. */
1239 close(REEXEC_CONFIG_PASS_FD);
1240 sock_in = sock_out = dup(STDIN_FILENO);
1242 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1243 close(REEXEC_STARTUP_PIPE_FD);
1246 sock_in = dup(STDIN_FILENO);
1247 sock_out = dup(STDOUT_FILENO);
1250 * We intentionally do not close the descriptors 0, 1, and 2
1251 * as our code for setting the descriptors won't work if
1252 * ttyfd happens to be one of those.
1254 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1255 dup2(fd, STDIN_FILENO);
1256 dup2(fd, STDOUT_FILENO);
1257 if (fd > STDOUT_FILENO)
1260 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1261 if ((options.protocol & SSH_PROTO_1) &&
1262 sensitive_data.server_key == NULL)
1263 generate_ephemeral_server_key();
1265 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1266 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1268 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1269 fatal("Too many listen sockets. "
1270 "Enlarge MAX_LISTEN_SOCKS");
1271 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1272 ntop, sizeof(ntop), strport, sizeof(strport),
1273 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1274 error("getnameinfo failed");
1277 /* Create socket for listening. */
1278 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1280 if (listen_sock < 0) {
1281 /* kernel may not support ipv6 */
1282 verbose("socket: %.100s", strerror(errno));
1285 if (set_nonblock(listen_sock) == -1) {
1290 * Set socket options.
1291 * Allow local port reuse in TIME_WAIT.
1293 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1294 &on, sizeof(on)) == -1)
1295 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1297 debug("Bind to port %s on %s.", strport, ntop);
1299 /* Bind the socket to the desired port. */
1300 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1302 error("Bind to port %s on %s failed: %.200s.",
1303 strport, ntop, strerror(errno));
1307 listen_socks[num_listen_socks] = listen_sock;
1310 /* Start listening on the port. */
1311 logit("Server listening on %s port %s.", ntop, strport);
1312 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1313 fatal("listen: %.100s", strerror(errno));
1316 freeaddrinfo(options.listen_addrs);
1318 if (!num_listen_socks)
1319 fatal("Cannot bind any address.");
1321 if (options.protocol & SSH_PROTO_1)
1322 generate_ephemeral_server_key();
1325 * Arrange to restart on SIGHUP. The handler needs
1328 signal(SIGHUP, sighup_handler);
1330 signal(SIGTERM, sigterm_handler);
1331 signal(SIGQUIT, sigterm_handler);
1333 /* Arrange SIGCHLD to be caught. */
1334 signal(SIGCHLD, main_sigchld_handler);
1336 /* Write out the pid file after the sigterm handler is setup */
1339 * Record our pid in /var/run/sshd.pid to make it
1340 * easier to kill the correct sshd. We don't want to
1341 * do this before the bind above because the bind will
1342 * fail if there already is a daemon, and this will
1343 * overwrite any old pid in the file.
1345 f = fopen(options.pid_file, "wb");
1347 error("Couldn't create pid file \"%s\": %s",
1348 options.pid_file, strerror(errno));
1350 fprintf(f, "%ld\n", (long) getpid());
1355 /* setup fd set for listen */
1358 for (i = 0; i < num_listen_socks; i++)
1359 if (listen_socks[i] > maxfd)
1360 maxfd = listen_socks[i];
1361 /* pipes connected to unauthenticated childs */
1362 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1363 for (i = 0; i < options.max_startups; i++)
1364 startup_pipes[i] = -1;
1367 * Stay listening for connections until the system crashes or
1368 * the daemon is killed with a signal.
1371 if (received_sighup)
1375 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1376 fdset = (fd_set *)xmalloc(fdsetsz);
1377 memset(fdset, 0, fdsetsz);
1379 for (i = 0; i < num_listen_socks; i++)
1380 FD_SET(listen_socks[i], fdset);
1381 for (i = 0; i < options.max_startups; i++)
1382 if (startup_pipes[i] != -1)
1383 FD_SET(startup_pipes[i], fdset);
1385 /* Wait in select until there is a connection. */
1386 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1387 if (ret < 0 && errno != EINTR)
1388 error("select: %.100s", strerror(errno));
1389 if (received_sigterm) {
1390 logit("Received signal %d; terminating.",
1391 (int) received_sigterm);
1392 close_listen_socks();
1393 unlink(options.pid_file);
1396 if (key_used && key_do_regen) {
1397 generate_ephemeral_server_key();
1404 for (i = 0; i < options.max_startups; i++)
1405 if (startup_pipes[i] != -1 &&
1406 FD_ISSET(startup_pipes[i], fdset)) {
1408 * the read end of the pipe is ready
1409 * if the child has closed the pipe
1410 * after successful authentication
1411 * or if the child has died
1413 close(startup_pipes[i]);
1414 startup_pipes[i] = -1;
1417 for (i = 0; i < num_listen_socks; i++) {
1418 if (!FD_ISSET(listen_socks[i], fdset))
1420 fromlen = sizeof(from);
1421 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1424 if (errno != EINTR && errno != EWOULDBLOCK)
1425 error("accept: %.100s", strerror(errno));
1428 if (unset_nonblock(newsock) == -1) {
1432 if (drop_connection(startups) == 1) {
1433 debug("drop connection #%d", startups);
1437 if (pipe(startup_p) == -1) {
1442 if (rexec_flag && socketpair(AF_UNIX,
1443 SOCK_STREAM, 0, config_s) == -1) {
1444 error("reexec socketpair: %s",
1447 close(startup_p[0]);
1448 close(startup_p[1]);
1452 for (j = 0; j < options.max_startups; j++)
1453 if (startup_pipes[j] == -1) {
1454 startup_pipes[j] = startup_p[0];
1455 if (maxfd < startup_p[0])
1456 maxfd = startup_p[0];
1462 * Got connection. Fork a child to handle it, unless
1463 * we are in debugging mode.
1467 * In debugging mode. Close the listening
1468 * socket, and start processing the
1469 * connection without forking.
1471 debug("Server will not fork when running in debugging mode.");
1472 close_listen_socks();
1475 close(startup_p[0]);
1476 close(startup_p[1]);
1480 send_rexec_state(config_s[0],
1487 * Normal production daemon. Fork, and have
1488 * the child process the connection. The
1489 * parent continues listening.
1491 if ((pid = fork()) == 0) {
1493 * Child. Close the listening and max_startup
1494 * sockets. Start using the accepted socket.
1495 * Reinitialize logging (since our pid has
1496 * changed). We break out of the loop to handle
1499 startup_pipe = startup_p[1];
1500 close_startup_pipes();
1501 close_listen_socks();
1504 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1511 /* Parent. Stay in the loop. */
1513 error("fork: %.100s", strerror(errno));
1515 debug("Forked child %ld.", (long)pid);
1517 close(startup_p[1]);
1520 send_rexec_state(config_s[0], &cfg);
1525 /* Mark that the key has been used (it was "given" to the child). */
1526 if ((options.protocol & SSH_PROTO_1) &&
1528 /* Schedule server key regeneration alarm. */
1529 signal(SIGALRM, key_regeneration_alarm);
1530 alarm(options.key_regeneration_time);
1536 /* Close the new socket (the child is now taking care of it). */
1539 /* child process check (or debug mode) */
1540 if (num_listen_socks < 0)
1545 /* This is the child processing a new connection. */
1546 setproctitle("%s", "[accepted]");
1549 * Create a new session and process group since the 4.4BSD
1550 * setlogin() affects the entire process group. We don't
1551 * want the child to be able to affect the parent.
1553 #if !defined(SSHD_ACQUIRES_CTTY)
1555 * If setsid is called, on some platforms sshd will later acquire a
1556 * controlling terminal which will result in "could not set
1557 * controlling tty" errors.
1559 if (!debug_flag && !inetd_flag && setsid() < 0)
1560 error("setsid: %.100s", strerror(errno));
1566 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1567 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1568 dup2(newsock, STDIN_FILENO);
1569 dup2(STDIN_FILENO, STDOUT_FILENO);
1570 if (startup_pipe == -1)
1571 close(REEXEC_STARTUP_PIPE_FD);
1573 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1575 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1577 if (startup_pipe != -1)
1578 close(startup_pipe);
1580 execv(rexec_argv[0], rexec_argv);
1582 /* Reexec has failed, fall back and continue */
1583 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1584 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1585 log_init(__progname, options.log_level,
1586 options.log_facility, log_stderr);
1589 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1591 close(REEXEC_CONFIG_PASS_FD);
1592 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1593 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1594 dup2(fd, STDIN_FILENO);
1595 dup2(fd, STDOUT_FILENO);
1596 if (fd > STDERR_FILENO)
1599 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1600 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1604 * Disable the key regeneration alarm. We will not regenerate the
1605 * key since we are no longer in a position to give it to anyone. We
1606 * will not restart on SIGHUP since it no longer makes sense.
1609 signal(SIGALRM, SIG_DFL);
1610 signal(SIGHUP, SIG_DFL);
1611 signal(SIGTERM, SIG_DFL);
1612 signal(SIGQUIT, SIG_DFL);
1613 signal(SIGCHLD, SIG_DFL);
1614 signal(SIGINT, SIG_DFL);
1616 /* Set SO_KEEPALIVE if requested. */
1617 if (options.tcp_keep_alive &&
1618 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
1620 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1623 * Register our connection. This turns encryption off because we do
1626 packet_set_connection(sock_in, sock_out);
1628 remote_port = get_remote_port();
1629 remote_ip = get_remote_ipaddr();
1632 /* Check whether logins are denied from this host. */
1633 if (packet_connection_is_on_socket()) {
1634 struct request_info req;
1636 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1639 if (!hosts_access(&req)) {
1640 debug("Connection refused by tcp wrapper");
1643 fatal("libwrap refuse returns");
1646 #endif /* LIBWRAP */
1648 /* Log the connection. */
1649 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1652 * We don\'t want to listen forever unless the other side
1653 * successfully authenticates itself. So we set up an alarm which is
1654 * cleared after successful authentication. A limit of zero
1655 * indicates no limit. Note that we don\'t set the alarm in debugging
1656 * mode; it is just annoying to have the server exit just when you
1657 * are about to discover the bug.
1659 signal(SIGALRM, grace_alarm_handler);
1661 alarm(options.login_grace_time);
1663 sshd_exchange_identification(sock_in, sock_out);
1665 packet_set_nonblocking();
1667 /* allocate authentication context */
1668 authctxt = xmalloc(sizeof(*authctxt));
1669 memset(authctxt, 0, sizeof(*authctxt));
1671 /* XXX global for cleanup, access from other modules */
1672 the_authctxt = authctxt;
1674 /* prepare buffer to collect messages to display to user after login */
1675 buffer_init(&loginmsg);
1678 if (privsep_preauth(authctxt) == 1)
1681 /* perform the key exchange */
1682 /* authenticate user and start session */
1685 do_authentication2(authctxt);
1688 do_authentication(authctxt);
1691 * If we use privilege separation, the unprivileged child transfers
1692 * the current keystate and exits
1695 mm_send_keystate(pmonitor);
1701 * In privilege separation, we fork another child and prepare
1702 * file descriptor passing.
1705 privsep_postauth(authctxt);
1706 /* the monitor process [priv] will not return */
1708 destroy_sensitive_data();
1711 /* Start session. */
1712 do_authenticated(authctxt);
1714 /* The connection has been terminated. */
1715 verbose("Closing connection to %.100s", remote_ip);
1718 if (options.use_pam)
1720 #endif /* USE_PAM */
1731 * Decrypt session_key_int using our private server key and private host key
1732 * (key with larger modulus first).
1735 ssh1_session_key(BIGNUM *session_key_int)
1739 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1740 /* Server key has bigger modulus. */
1741 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1742 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1743 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1744 get_remote_ipaddr(),
1745 BN_num_bits(sensitive_data.server_key->rsa->n),
1746 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1747 SSH_KEY_BITS_RESERVED);
1749 if (rsa_private_decrypt(session_key_int, session_key_int,
1750 sensitive_data.server_key->rsa) <= 0)
1752 if (rsa_private_decrypt(session_key_int, session_key_int,
1753 sensitive_data.ssh1_host_key->rsa) <= 0)
1756 /* Host key has bigger modulus (or they are equal). */
1757 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1758 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1759 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1760 get_remote_ipaddr(),
1761 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1762 BN_num_bits(sensitive_data.server_key->rsa->n),
1763 SSH_KEY_BITS_RESERVED);
1765 if (rsa_private_decrypt(session_key_int, session_key_int,
1766 sensitive_data.ssh1_host_key->rsa) < 0)
1768 if (rsa_private_decrypt(session_key_int, session_key_int,
1769 sensitive_data.server_key->rsa) < 0)
1782 BIGNUM *session_key_int;
1783 u_char session_key[SSH_SESSION_KEY_LENGTH];
1785 u_int cipher_type, auth_mask, protocol_flags;
1789 * Generate check bytes that the client must send back in the user
1790 * packet in order for it to be accepted; this is used to defy ip
1791 * spoofing attacks. Note that this only works against somebody
1792 * doing IP spoofing from a remote machine; any machine on the local
1793 * network can still see outgoing packets and catch the random
1794 * cookie. This only affects rhosts authentication, and this is one
1795 * of the reasons why it is inherently insecure.
1797 for (i = 0; i < 8; i++) {
1800 cookie[i] = rnd & 0xff;
1805 * Send our public key. We include in the packet 64 bits of random
1806 * data that must be matched in the reply in order to prevent IP
1809 packet_start(SSH_SMSG_PUBLIC_KEY);
1810 for (i = 0; i < 8; i++)
1811 packet_put_char(cookie[i]);
1813 /* Store our public server RSA key. */
1814 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1815 packet_put_bignum(sensitive_data.server_key->rsa->e);
1816 packet_put_bignum(sensitive_data.server_key->rsa->n);
1818 /* Store our public host RSA key. */
1819 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1820 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1821 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1823 /* Put protocol flags. */
1824 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1826 /* Declare which ciphers we support. */
1827 packet_put_int(cipher_mask_ssh1(0));
1829 /* Declare supported authentication types. */
1831 if (options.rhosts_rsa_authentication)
1832 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1833 if (options.rsa_authentication)
1834 auth_mask |= 1 << SSH_AUTH_RSA;
1835 if (options.challenge_response_authentication == 1)
1836 auth_mask |= 1 << SSH_AUTH_TIS;
1837 if (options.password_authentication)
1838 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1839 packet_put_int(auth_mask);
1841 /* Send the packet and wait for it to be sent. */
1843 packet_write_wait();
1845 debug("Sent %d bit server key and %d bit host key.",
1846 BN_num_bits(sensitive_data.server_key->rsa->n),
1847 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1849 /* Read clients reply (cipher type and session key). */
1850 packet_read_expect(SSH_CMSG_SESSION_KEY);
1852 /* Get cipher type and check whether we accept this. */
1853 cipher_type = packet_get_char();
1855 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1856 packet_disconnect("Warning: client selects unsupported cipher.");
1858 /* Get check bytes from the packet. These must match those we
1859 sent earlier with the public key packet. */
1860 for (i = 0; i < 8; i++)
1861 if (cookie[i] != packet_get_char())
1862 packet_disconnect("IP Spoofing check bytes do not match.");
1864 debug("Encryption type: %.200s", cipher_name(cipher_type));
1866 /* Get the encrypted integer. */
1867 if ((session_key_int = BN_new()) == NULL)
1868 fatal("do_ssh1_kex: BN_new failed");
1869 packet_get_bignum(session_key_int);
1871 protocol_flags = packet_get_int();
1872 packet_set_protocol_flags(protocol_flags);
1875 /* Decrypt session_key_int using host/server keys */
1876 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1879 * Extract session key from the decrypted integer. The key is in the
1880 * least significant 256 bits of the integer; the first byte of the
1881 * key is in the highest bits.
1884 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1885 len = BN_num_bytes(session_key_int);
1886 if (len < 0 || len > sizeof(session_key)) {
1887 error("do_connection: bad session key len from %s: "
1888 "session_key_int %d > sizeof(session_key) %lu",
1889 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1892 memset(session_key, 0, sizeof(session_key));
1893 BN_bn2bin(session_key_int,
1894 session_key + sizeof(session_key) - len);
1896 derive_ssh1_session_id(
1897 sensitive_data.ssh1_host_key->rsa->n,
1898 sensitive_data.server_key->rsa->n,
1899 cookie, session_id);
1901 * Xor the first 16 bytes of the session key with the
1904 for (i = 0; i < 16; i++)
1905 session_key[i] ^= session_id[i];
1909 int bytes = BN_num_bytes(session_key_int);
1910 u_char *buf = xmalloc(bytes);
1913 logit("do_connection: generating a fake encryption key");
1914 BN_bn2bin(session_key_int, buf);
1916 MD5_Update(&md, buf, bytes);
1917 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1918 MD5_Final(session_key, &md);
1920 MD5_Update(&md, session_key, 16);
1921 MD5_Update(&md, buf, bytes);
1922 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1923 MD5_Final(session_key + 16, &md);
1924 memset(buf, 0, bytes);
1926 for (i = 0; i < 16; i++)
1927 session_id[i] = session_key[i] ^ session_key[i + 16];
1929 /* Destroy the private and public keys. No longer. */
1930 destroy_sensitive_data();
1933 mm_ssh1_session_id(session_id);
1935 /* Destroy the decrypted integer. It is no longer needed. */
1936 BN_clear_free(session_key_int);
1938 /* Set the session key. From this on all communications will be encrypted. */
1939 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1941 /* Destroy our copy of the session key. It is no longer needed. */
1942 memset(session_key, 0, sizeof(session_key));
1944 debug("Received session key; encryption turned on.");
1946 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1947 packet_start(SSH_SMSG_SUCCESS);
1949 packet_write_wait();
1953 * SSH2 key exchange: diffie-hellman-group1-sha1
1960 if (options.ciphers != NULL) {
1961 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1962 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1964 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1965 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1966 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1967 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1969 if (options.macs != NULL) {
1970 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1971 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1973 if (!options.compression) {
1974 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1975 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1977 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1979 /* start key exchange */
1980 kex = kex_setup(myproposal);
1981 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1982 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1983 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1985 kex->client_version_string=client_version_string;
1986 kex->server_version_string=server_version_string;
1987 kex->load_host_key=&get_hostkey_by_type;
1988 kex->host_key_index=&get_hostkey_index;
1992 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1994 session_id2 = kex->session_id;
1995 session_id2_len = kex->session_id_len;
1998 /* send 1st encrypted/maced/compressed message */
1999 packet_start(SSH2_MSG_IGNORE);
2000 packet_put_cstring("markus");
2002 packet_write_wait();
2007 /* server specific fatal cleanup */
2012 do_cleanup(the_authctxt);