1 /* $OpenBSD: sshd.c,v 1.351 2007/05/22 10:18:52 djm 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"
74 #include <openssl/dh.h>
75 #include <openssl/bn.h>
76 #include <openssl/md5.h>
77 #include <openssl/rand.h>
78 #ifdef HAVE_SECUREWARE
79 #include <sys/security.h>
99 #include "myproposal.h"
100 #include "authfile.h"
101 #include "pathnames.h"
102 #include "atomicio.h"
103 #include "canohost.h"
104 #include "hostfile.h"
108 #include "dispatch.h"
109 #include "channels.h"
111 #include "monitor_mm.h"
116 #include "monitor_wrap.h"
117 #include "monitor_fdpass.h"
120 #ifdef USE_SECURITY_SESSION_API
121 #include <Security/AuthSession.h>
127 int allow_severity = LOG_INFO;
128 int deny_severity = LOG_WARNING;
136 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
137 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
138 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
139 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
144 extern char *__progname;
146 /* Server configuration options. */
147 ServerOptions options;
149 /* Name of the server configuration file. */
150 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
153 * Debug mode flag. This can be set on the command line. If debug
154 * mode is enabled, extra debugging output will be sent to the system
155 * log, the daemon will not go to background, and will exit after processing
156 * the first connection.
160 /* Flag indicating that the daemon should only test the configuration and keys. */
163 /* Flag indicating that the daemon is being started from inetd. */
166 /* Flag indicating that sshd should not detach and become a daemon. */
167 int no_daemon_flag = 0;
169 /* debug goes to stderr unless inetd_flag is set */
172 /* Saved arguments to main(). */
177 int rexeced_flag = 0;
183 * The sockets that the server is listening; this is used in the SIGHUP
186 #define MAX_LISTEN_SOCKS 16
187 int listen_socks[MAX_LISTEN_SOCKS];
188 int num_listen_socks = 0;
191 * the client's version string, passed by sshd2 in compat mode. if != NULL,
192 * sshd will skip the version-number exchange
194 char *client_version_string = NULL;
195 char *server_version_string = NULL;
197 /* for rekeying XXX fixme */
201 * Any really sensitive data in the application is contained in this
202 * structure. The idea is that this structure could be locked into memory so
203 * that the pages do not get written into swap. However, there are some
204 * problems. The private key contains BIGNUMs, and we do not (in principle)
205 * have access to the internals of them, and locking just the structure is
206 * not very useful. Currently, memory locking is not implemented.
209 Key *server_key; /* ephemeral server key */
210 Key *ssh1_host_key; /* ssh1 host key */
211 Key **host_keys; /* all private host keys */
214 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
218 * Flag indicating whether the RSA server key needs to be regenerated.
219 * Is set in the SIGALRM handler and cleared when the key is regenerated.
221 static volatile sig_atomic_t key_do_regen = 0;
223 /* This is set to true when a signal is received. */
224 static volatile sig_atomic_t received_sighup = 0;
225 static volatile sig_atomic_t received_sigterm = 0;
227 /* session identifier, used by RSA-auth */
228 u_char session_id[16];
231 u_char *session_id2 = NULL;
232 u_int session_id2_len = 0;
234 /* record remote hostname or ip */
235 u_int utmp_len = MAXHOSTNAMELEN;
237 /* options.max_startup sized array of fd ints */
238 int *startup_pipes = NULL;
239 int startup_pipe; /* in child */
241 /* variables used for privilege separation */
242 int use_privsep = -1;
243 struct monitor *pmonitor = NULL;
245 /* global authentication context */
246 Authctxt *the_authctxt = NULL;
248 /* sshd_config buffer */
251 /* message to be displayed after login */
254 /* Unprivileged user */
255 struct passwd *privsep_pw = NULL;
257 /* Prototypes for various functions defined later in this file. */
258 void destroy_sensitive_data(void);
259 void demote_sensitive_data(void);
261 static void do_ssh1_kex(void);
262 static void do_ssh2_kex(void);
265 * Close all listening sockets
268 close_listen_socks(void)
272 for (i = 0; i < num_listen_socks; i++)
273 close(listen_socks[i]);
274 num_listen_socks = -1;
278 close_startup_pipes(void)
283 for (i = 0; i < options.max_startups; i++)
284 if (startup_pipes[i] != -1)
285 close(startup_pipes[i]);
289 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
290 * the effect is to reread the configuration file (and to regenerate
296 sighup_handler(int sig)
298 int save_errno = errno;
301 signal(SIGHUP, sighup_handler);
306 * Called from the main program after receiving SIGHUP.
307 * Restarts the server.
312 logit("Received SIGHUP; restarting.");
313 close_listen_socks();
314 close_startup_pipes();
315 alarm(0); /* alarm timer persists across exec */
316 execv(saved_argv[0], saved_argv);
317 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
323 * Generic signal handler for terminating signals in the master daemon.
327 sigterm_handler(int sig)
329 received_sigterm = sig;
333 * SIGCHLD handler. This is called whenever a child dies. This will then
334 * reap any zombies left by exited children.
338 main_sigchld_handler(int sig)
340 int save_errno = errno;
344 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
345 (pid < 0 && errno == EINTR))
348 signal(SIGCHLD, main_sigchld_handler);
353 * Signal handler for the alarm after the login grace period has expired.
357 grace_alarm_handler(int sig)
359 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
360 kill(pmonitor->m_pid, SIGALRM);
362 /* Log error and exit. */
363 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
367 * Signal handler for the key regeneration alarm. Note that this
368 * alarm only occurs in the daemon waiting for connections, and it does not
369 * do anything with the private key or random state before forking.
370 * Thus there should be no concurrency control/asynchronous execution
374 generate_ephemeral_server_key(void)
379 verbose("Generating %s%d bit RSA key.",
380 sensitive_data.server_key ? "new " : "", options.server_key_bits);
381 if (sensitive_data.server_key != NULL)
382 key_free(sensitive_data.server_key);
383 sensitive_data.server_key = key_generate(KEY_RSA1,
384 options.server_key_bits);
385 verbose("RSA key generation complete.");
387 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
390 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
398 key_regeneration_alarm(int sig)
400 int save_errno = errno;
402 signal(SIGALRM, SIG_DFL);
408 sshd_exchange_identification(int sock_in, int sock_out)
412 int remote_major, remote_minor;
415 char buf[256]; /* Must not be larger than remote_version. */
416 char remote_version[256]; /* Must be at least as big as buf. */
418 if ((options.protocol & SSH_PROTO_1) &&
419 (options.protocol & SSH_PROTO_2)) {
420 major = PROTOCOL_MAJOR_1;
422 } else if (options.protocol & SSH_PROTO_2) {
423 major = PROTOCOL_MAJOR_2;
424 minor = PROTOCOL_MINOR_2;
426 major = PROTOCOL_MAJOR_1;
427 minor = PROTOCOL_MINOR_1;
429 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_RELEASE);
430 server_version_string = xstrdup(buf);
432 /* Send our protocol version identification. */
433 if (atomicio(vwrite, sock_out, server_version_string,
434 strlen(server_version_string))
435 != strlen(server_version_string)) {
436 logit("Could not write ident string to %s", get_remote_ipaddr());
440 /* Read other sides version identification. */
441 memset(buf, 0, sizeof(buf));
442 for (i = 0; i < sizeof(buf) - 1; i++) {
443 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
444 logit("Did not receive identification string from %s",
445 get_remote_ipaddr());
448 if (buf[i] == '\r') {
450 /* Kludge for F-Secure Macintosh < 1.0.2 */
452 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
456 if (buf[i] == '\n') {
461 buf[sizeof(buf) - 1] = 0;
462 client_version_string = xstrdup(buf);
465 * Check that the versions match. In future this might accept
466 * several versions and set appropriate flags to handle them.
468 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
469 &remote_major, &remote_minor, remote_version) != 3) {
470 s = "Protocol mismatch.\n";
471 (void) atomicio(vwrite, sock_out, s, strlen(s));
474 logit("Bad protocol version identification '%.100s' from %s",
475 client_version_string, get_remote_ipaddr());
478 debug("Client protocol version %d.%d; client software version %.100s",
479 remote_major, remote_minor, remote_version);
480 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s",
481 get_remote_ipaddr(), get_remote_port(),
482 remote_major, remote_minor, remote_version);
484 compat_datafellows(remote_version);
486 if (datafellows & SSH_BUG_PROBE) {
487 logit("probed from %s with %s. Don't panic.",
488 get_remote_ipaddr(), client_version_string);
492 if (datafellows & SSH_BUG_SCANNER) {
493 logit("scanned from %s with %s. Don't panic.",
494 get_remote_ipaddr(), client_version_string);
499 switch (remote_major) {
501 if (remote_minor == 99) {
502 if (options.protocol & SSH_PROTO_2)
508 if (!(options.protocol & SSH_PROTO_1)) {
512 if (remote_minor < 3) {
513 packet_disconnect("Your ssh version is too old and "
514 "is no longer supported. Please install a newer version.");
515 } else if (remote_minor == 3) {
516 /* note that this disables agent-forwarding */
521 if (options.protocol & SSH_PROTO_2) {
530 chop(server_version_string);
531 debug("Local version string %.200s", server_version_string);
534 s = "Protocol major versions differ.\n";
535 (void) atomicio(vwrite, sock_out, s, strlen(s));
538 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
540 server_version_string, client_version_string);
545 /* Destroy the host and server keys. They will no longer be needed. */
547 destroy_sensitive_data(void)
551 if (sensitive_data.server_key) {
552 key_free(sensitive_data.server_key);
553 sensitive_data.server_key = NULL;
555 for (i = 0; i < options.num_host_key_files; i++) {
556 if (sensitive_data.host_keys[i]) {
557 key_free(sensitive_data.host_keys[i]);
558 sensitive_data.host_keys[i] = NULL;
561 sensitive_data.ssh1_host_key = NULL;
562 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
565 /* Demote private to public keys for network child */
567 demote_sensitive_data(void)
572 if (sensitive_data.server_key) {
573 tmp = key_demote(sensitive_data.server_key);
574 key_free(sensitive_data.server_key);
575 sensitive_data.server_key = tmp;
578 for (i = 0; i < options.num_host_key_files; i++) {
579 if (sensitive_data.host_keys[i]) {
580 tmp = key_demote(sensitive_data.host_keys[i]);
581 key_free(sensitive_data.host_keys[i]);
582 sensitive_data.host_keys[i] = tmp;
583 if (tmp->type == KEY_RSA1)
584 sensitive_data.ssh1_host_key = tmp;
588 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
592 privsep_preauth_child(void)
598 /* Enable challenge-response authentication for privilege separation */
599 privsep_challenge_enable();
601 for (i = 0; i < 256; i++)
602 rnd[i] = arc4random();
603 RAND_seed(rnd, sizeof(rnd));
605 /* Demote the private keys to public keys. */
606 demote_sensitive_data();
608 /* Change our root directory */
609 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
610 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
612 if (chdir("/") == -1)
613 fatal("chdir(\"/\"): %s", strerror(errno));
615 /* Drop our privileges */
616 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
617 (u_int)privsep_pw->pw_gid);
619 /* XXX not ready, too heavy after chroot */
620 do_setusercontext(privsep_pw);
622 gidset[0] = privsep_pw->pw_gid;
623 if (setgroups(1, gidset) < 0)
624 fatal("setgroups: %.100s", strerror(errno));
625 permanently_set_uid(privsep_pw);
630 privsep_preauth(Authctxt *authctxt)
635 /* Set up unprivileged child process to deal with network data */
636 pmonitor = monitor_init();
637 /* Store a pointer to the kex for later rekeying */
638 pmonitor->m_pkex = &xxx_kex;
642 fatal("fork of unprivileged child failed");
643 } else if (pid != 0) {
644 debug2("Network child is on pid %ld", (long)pid);
646 close(pmonitor->m_recvfd);
647 pmonitor->m_pid = pid;
648 monitor_child_preauth(authctxt, pmonitor);
649 close(pmonitor->m_sendfd);
652 monitor_sync(pmonitor);
654 /* Wait for the child's exit status */
655 while (waitpid(pid, &status, 0) < 0)
662 close(pmonitor->m_sendfd);
664 /* Demote the child */
665 if (getuid() == 0 || geteuid() == 0)
666 privsep_preauth_child();
667 setproctitle("%s", "[net]");
673 privsep_postauth(Authctxt *authctxt)
675 #ifdef DISABLE_FD_PASSING
678 if (authctxt->pw->pw_uid == 0 || options.use_login) {
680 /* File descriptor passing is broken or root login */
685 /* New socket pair */
686 monitor_reinit(pmonitor);
688 pmonitor->m_pid = fork();
689 if (pmonitor->m_pid == -1)
690 fatal("fork of unprivileged child failed");
691 else if (pmonitor->m_pid != 0) {
692 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
693 close(pmonitor->m_recvfd);
694 buffer_clear(&loginmsg);
695 monitor_child_postauth(pmonitor);
701 close(pmonitor->m_sendfd);
703 /* Demote the private keys to public keys. */
704 demote_sensitive_data();
706 /* Drop privileges */
707 do_setusercontext(authctxt->pw);
710 /* It is safe now to apply the key state */
711 monitor_apply_keystate(pmonitor);
714 * Tell the packet layer that authentication was successful, since
715 * this information is not part of the key state.
717 packet_set_authenticated();
721 list_hostkey_types(void)
729 for (i = 0; i < options.num_host_key_files; i++) {
730 Key *key = sensitive_data.host_keys[i];
736 if (buffer_len(&b) > 0)
737 buffer_append(&b, ",", 1);
738 p = key_ssh_name(key);
739 buffer_append(&b, p, strlen(p));
743 buffer_append(&b, "\0", 1);
744 ret = xstrdup(buffer_ptr(&b));
746 debug("list_hostkey_types: %s", ret);
751 get_hostkey_by_type(int type)
755 for (i = 0; i < options.num_host_key_files; i++) {
756 Key *key = sensitive_data.host_keys[i];
757 if (key != NULL && key->type == type)
764 get_hostkey_by_index(int ind)
766 if (ind < 0 || ind >= options.num_host_key_files)
768 return (sensitive_data.host_keys[ind]);
772 get_hostkey_index(Key *key)
776 for (i = 0; i < options.num_host_key_files; i++) {
777 if (key == sensitive_data.host_keys[i])
784 * returns 1 if connection should be dropped, 0 otherwise.
785 * dropping starts at connection #max_startups_begin with a probability
786 * of (max_startups_rate/100). the probability increases linearly until
787 * all connections are dropped for startups > max_startups
790 drop_connection(int startups)
794 if (startups < options.max_startups_begin)
796 if (startups >= options.max_startups)
798 if (options.max_startups_rate == 100)
801 p = 100 - options.max_startups_rate;
802 p *= startups - options.max_startups_begin;
803 p /= options.max_startups - options.max_startups_begin;
804 p += options.max_startups_rate;
805 r = arc4random() % 100;
807 debug("drop_connection: p %d, r %d", p, r);
808 return (r < p) ? 1 : 0;
814 fprintf(stderr, "%s, %s\n",
815 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
817 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
818 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
824 send_rexec_state(int fd, Buffer *conf)
828 debug3("%s: entering fd = %d config len %d", __func__, fd,
832 * Protocol from reexec master to child:
833 * string configuration
834 * u_int ephemeral_key_follows
835 * bignum e (only if ephemeral_key_follows == 1)
841 * string rngseed (only if OpenSSL is not self-seeded)
844 buffer_put_cstring(&m, buffer_ptr(conf));
846 if (sensitive_data.server_key != NULL &&
847 sensitive_data.server_key->type == KEY_RSA1) {
848 buffer_put_int(&m, 1);
849 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
850 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
851 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
852 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
853 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
854 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
856 buffer_put_int(&m, 0);
858 #ifndef OPENSSL_PRNG_ONLY
859 rexec_send_rng_seed(&m);
862 if (ssh_msg_send(fd, 0, &m) == -1)
863 fatal("%s: ssh_msg_send failed", __func__);
867 debug3("%s: done", __func__);
871 recv_rexec_state(int fd, Buffer *conf)
877 debug3("%s: entering fd = %d", __func__, fd);
881 if (ssh_msg_recv(fd, &m) == -1)
882 fatal("%s: ssh_msg_recv failed", __func__);
883 if (buffer_get_char(&m) != 0)
884 fatal("%s: rexec version mismatch", __func__);
886 cp = buffer_get_string(&m, &len);
888 buffer_append(conf, cp, len + 1);
891 if (buffer_get_int(&m)) {
892 if (sensitive_data.server_key != NULL)
893 key_free(sensitive_data.server_key);
894 sensitive_data.server_key = key_new_private(KEY_RSA1);
895 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
896 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
897 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
898 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
899 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
900 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
901 rsa_generate_additional_parameters(
902 sensitive_data.server_key->rsa);
905 #ifndef OPENSSL_PRNG_ONLY
906 rexec_recv_rng_seed(&m);
911 debug3("%s: done", __func__);
914 /* Accept a connection from inetd */
916 server_accept_inetd(int *sock_in, int *sock_out)
922 close(REEXEC_CONFIG_PASS_FD);
923 *sock_in = *sock_out = dup(STDIN_FILENO);
925 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
926 close(REEXEC_STARTUP_PIPE_FD);
929 *sock_in = dup(STDIN_FILENO);
930 *sock_out = dup(STDOUT_FILENO);
933 * We intentionally do not close the descriptors 0, 1, and 2
934 * as our code for setting the descriptors won't work if
935 * ttyfd happens to be one of those.
937 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
938 dup2(fd, STDIN_FILENO);
939 dup2(fd, STDOUT_FILENO);
940 if (fd > STDOUT_FILENO)
943 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
947 * Listen for TCP connections
952 int ret, listen_sock, on = 1;
954 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
956 int socksizelen = sizeof(int);
958 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
959 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
961 if (num_listen_socks >= MAX_LISTEN_SOCKS)
962 fatal("Too many listen sockets. "
963 "Enlarge MAX_LISTEN_SOCKS");
964 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
965 ntop, sizeof(ntop), strport, sizeof(strport),
966 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
967 error("getnameinfo failed: %.100s",
968 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
972 /* Create socket for listening. */
973 listen_sock = socket(ai->ai_family, ai->ai_socktype,
975 if (listen_sock < 0) {
976 /* kernel may not support ipv6 */
977 verbose("socket: %.100s", strerror(errno));
980 if (set_nonblock(listen_sock) == -1) {
985 * Set socket options.
986 * Allow local port reuse in TIME_WAIT.
988 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
989 &on, sizeof(on)) == -1)
990 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
992 debug("Bind to port %s on %s.", strport, ntop);
994 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF,
995 &socksize, &socksizelen);
996 debug("Server TCP RWIN socket size: %d", socksize);
997 debug("HPN Buffer Size: %d", options.hpn_buffer_size);
999 /* Bind the socket to the desired port. */
1000 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1001 error("Bind to port %s on %s failed: %.200s.",
1002 strport, ntop, strerror(errno));
1006 listen_socks[num_listen_socks] = listen_sock;
1009 /* Start listening on the port. */
1010 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1011 fatal("listen on [%s]:%s: %.100s",
1012 ntop, strport, strerror(errno));
1013 logit("Server listening on %s port %s.", ntop, strport);
1015 freeaddrinfo(options.listen_addrs);
1017 if (!num_listen_socks)
1018 fatal("Cannot bind any address.");
1022 * The main TCP accept loop. Note that, for the non-debug case, returns
1023 * from this function are in a forked subprocess.
1026 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1029 int i, j, ret, maxfd;
1030 int key_used = 0, startups = 0;
1031 int startup_p[2] = { -1 , -1 };
1032 struct sockaddr_storage from;
1036 /* setup fd set for accept */
1039 for (i = 0; i < num_listen_socks; i++)
1040 if (listen_socks[i] > maxfd)
1041 maxfd = listen_socks[i];
1042 /* pipes connected to unauthenticated childs */
1043 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1044 for (i = 0; i < options.max_startups; i++)
1045 startup_pipes[i] = -1;
1048 * Stay listening for connections until the system crashes or
1049 * the daemon is killed with a signal.
1052 if (received_sighup)
1056 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1059 for (i = 0; i < num_listen_socks; i++)
1060 FD_SET(listen_socks[i], fdset);
1061 for (i = 0; i < options.max_startups; i++)
1062 if (startup_pipes[i] != -1)
1063 FD_SET(startup_pipes[i], fdset);
1065 /* Wait in select until there is a connection. */
1066 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1067 if (ret < 0 && errno != EINTR)
1068 error("select: %.100s", strerror(errno));
1069 if (received_sigterm) {
1070 logit("Received signal %d; terminating.",
1071 (int) received_sigterm);
1072 close_listen_socks();
1073 unlink(options.pid_file);
1076 if (key_used && key_do_regen) {
1077 generate_ephemeral_server_key();
1084 for (i = 0; i < options.max_startups; i++)
1085 if (startup_pipes[i] != -1 &&
1086 FD_ISSET(startup_pipes[i], fdset)) {
1088 * the read end of the pipe is ready
1089 * if the child has closed the pipe
1090 * after successful authentication
1091 * or if the child has died
1093 close(startup_pipes[i]);
1094 startup_pipes[i] = -1;
1097 for (i = 0; i < num_listen_socks; i++) {
1098 if (!FD_ISSET(listen_socks[i], fdset))
1100 fromlen = sizeof(from);
1101 *newsock = accept(listen_socks[i],
1102 (struct sockaddr *)&from, &fromlen);
1104 if (errno != EINTR && errno != EWOULDBLOCK)
1105 error("accept: %.100s", strerror(errno));
1108 if (unset_nonblock(*newsock) == -1) {
1112 if (drop_connection(startups) == 1) {
1113 debug("drop connection #%d", startups);
1117 if (pipe(startup_p) == -1) {
1122 if (rexec_flag && socketpair(AF_UNIX,
1123 SOCK_STREAM, 0, config_s) == -1) {
1124 error("reexec socketpair: %s",
1127 close(startup_p[0]);
1128 close(startup_p[1]);
1132 for (j = 0; j < options.max_startups; j++)
1133 if (startup_pipes[j] == -1) {
1134 startup_pipes[j] = startup_p[0];
1135 if (maxfd < startup_p[0])
1136 maxfd = startup_p[0];
1142 * Got connection. Fork a child to handle it, unless
1143 * we are in debugging mode.
1147 * In debugging mode. Close the listening
1148 * socket, and start processing the
1149 * connection without forking.
1151 debug("Server will not fork when running in debugging mode.");
1152 close_listen_socks();
1153 *sock_in = *newsock;
1154 *sock_out = *newsock;
1155 close(startup_p[0]);
1156 close(startup_p[1]);
1160 send_rexec_state(config_s[0],
1168 * Normal production daemon. Fork, and have
1169 * the child process the connection. The
1170 * parent continues listening.
1172 platform_pre_fork();
1173 if ((pid = fork()) == 0) {
1175 * Child. Close the listening and
1176 * max_startup sockets. Start using
1177 * the accepted socket. Reinitialize
1178 * logging (since our pid has changed).
1179 * We break out of the loop to handle
1182 platform_post_fork_child();
1183 startup_pipe = startup_p[1];
1184 close_startup_pipes();
1185 close_listen_socks();
1186 *sock_in = *newsock;
1187 *sock_out = *newsock;
1188 log_init(__progname,
1190 options.log_facility,
1197 /* Parent. Stay in the loop. */
1198 platform_post_fork_parent(pid);
1200 error("fork: %.100s", strerror(errno));
1202 debug("Forked child %ld.", (long)pid);
1204 close(startup_p[1]);
1207 send_rexec_state(config_s[0], &cfg);
1213 * Mark that the key has been used (it
1214 * was "given" to the child).
1216 if ((options.protocol & SSH_PROTO_1) &&
1218 /* Schedule server key regeneration alarm. */
1219 signal(SIGALRM, key_regeneration_alarm);
1220 alarm(options.key_regeneration_time);
1227 * Ensure that our random state differs
1228 * from that of the child
1233 /* child process check (or debug mode) */
1234 if (num_listen_socks < 0)
1241 * Main program for the daemon.
1244 main(int ac, char **av)
1246 extern char *optarg;
1249 int sock_in = -1, sock_out = -1, newsock = -1;
1250 const char *remote_ip;
1253 int config_s[2] = { -1 , -1 };
1257 #ifdef HAVE_SECUREWARE
1258 (void)set_auth_parameters(ac, av);
1260 __progname = ssh_get_progname(av[0]);
1263 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1266 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1267 for (i = 0; i < ac; i++)
1268 saved_argv[i] = xstrdup(av[i]);
1269 saved_argv[i] = NULL;
1271 #ifndef HAVE_SETPROCTITLE
1272 /* Prepare for later setproctitle emulation */
1273 compat_init_setproctitle(ac, av);
1277 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1278 debug("setgroups(): %.200s", strerror(errno));
1280 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1283 /* Initialize configuration options to their default values. */
1284 initialize_server_options(&options);
1286 /* Parse command-line arguments. */
1287 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
1290 options.address_family = AF_INET;
1293 options.address_family = AF_INET6;
1296 config_file_name = optarg;
1299 if (debug_flag == 0) {
1301 options.log_level = SYSLOG_LEVEL_DEBUG1;
1302 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1303 options.log_level++;
1325 options.log_level = SYSLOG_LEVEL_QUIET;
1328 options.server_key_bits = (int)strtonum(optarg, 256,
1332 options.ports_from_cmdline = 1;
1333 if (options.num_ports >= MAX_PORTS) {
1334 fprintf(stderr, "too many ports.\n");
1337 options.ports[options.num_ports++] = a2port(optarg);
1338 if (options.ports[options.num_ports-1] == 0) {
1339 fprintf(stderr, "Bad port number.\n");
1344 if ((options.login_grace_time = convtime(optarg)) == -1) {
1345 fprintf(stderr, "Invalid login grace time.\n");
1350 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1351 fprintf(stderr, "Invalid key regeneration interval.\n");
1356 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1357 fprintf(stderr, "too many host keys.\n");
1360 options.host_key_files[options.num_host_key_files++] = optarg;
1366 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1367 if (utmp_len > MAXHOSTNAMELEN) {
1368 fprintf(stderr, "Invalid utmp length.\n");
1373 line = xstrdup(optarg);
1374 if (process_server_config_line(&options, line,
1375 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1385 if (rexeced_flag || inetd_flag)
1387 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1388 fatal("sshd re-exec requires execution with an absolute path");
1390 closefrom(REEXEC_MIN_FREE_FD);
1392 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1394 SSLeay_add_all_algorithms();
1397 * Force logging to stderr until we have loaded the private host
1398 * key (unless started from inetd)
1400 log_init(__progname,
1401 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1402 SYSLOG_LEVEL_INFO : options.log_level,
1403 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1404 SYSLOG_FACILITY_AUTH : options.log_facility,
1405 log_stderr || !inetd_flag);
1408 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1409 * root's environment
1411 if (getenv("KRB5CCNAME") != NULL)
1412 unsetenv("KRB5CCNAME");
1415 /* Cray can define user privs drop all privs now!
1416 * Not needed on PRIV_SU systems!
1421 sensitive_data.server_key = NULL;
1422 sensitive_data.ssh1_host_key = NULL;
1423 sensitive_data.have_ssh1_key = 0;
1424 sensitive_data.have_ssh2_key = 0;
1426 /* Fetch our configuration */
1429 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1431 load_server_config(config_file_name, &cfg);
1433 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1434 &cfg, NULL, NULL, NULL);
1438 /* Fill in default values for those options not explicitly set. */
1439 fill_default_server_options(&options);
1441 /* challenge-response is implemented via keyboard interactive */
1442 if (options.challenge_response_authentication)
1443 options.kbd_interactive_authentication = 1;
1445 /* set default channel AF */
1446 channel_set_af(options.address_family);
1448 /* Check that there are no remaining arguments. */
1450 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1454 debug("sshd version %.100s", SSH_RELEASE);
1456 /* Store privilege separation user for later use if required. */
1457 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1458 if (use_privsep || options.kerberos_authentication)
1459 fatal("Privilege separation user %s does not exist",
1462 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1463 privsep_pw = pwcopy(privsep_pw);
1464 xfree(privsep_pw->pw_passwd);
1465 privsep_pw->pw_passwd = xstrdup("*");
1469 /* load private host keys */
1470 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1472 for (i = 0; i < options.num_host_key_files; i++)
1473 sensitive_data.host_keys[i] = NULL;
1475 for (i = 0; i < options.num_host_key_files; i++) {
1476 key = key_load_private(options.host_key_files[i], "", NULL);
1477 sensitive_data.host_keys[i] = key;
1479 error("Could not load host key: %s",
1480 options.host_key_files[i]);
1481 sensitive_data.host_keys[i] = NULL;
1484 switch (key->type) {
1486 sensitive_data.ssh1_host_key = key;
1487 sensitive_data.have_ssh1_key = 1;
1491 sensitive_data.have_ssh2_key = 1;
1494 debug("private host key: #%d type %d %s", i, key->type,
1497 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1498 logit("Disabling protocol version 1. Could not load host key");
1499 options.protocol &= ~SSH_PROTO_1;
1502 /* The GSSAPI key exchange can run without a host key */
1503 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1504 logit("Disabling protocol version 2. Could not load host key");
1505 options.protocol &= ~SSH_PROTO_2;
1508 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1509 logit("sshd: no hostkeys available -- exiting.");
1513 /* Check certain values for sanity. */
1514 if (options.protocol & SSH_PROTO_1) {
1515 if (options.server_key_bits < 512 ||
1516 options.server_key_bits > 32768) {
1517 fprintf(stderr, "Bad server key size.\n");
1521 * Check that server and host key lengths differ sufficiently. This
1522 * is necessary to make double encryption work with rsaref. Oh, I
1523 * hate software patents. I dont know if this can go? Niels
1525 if (options.server_key_bits >
1526 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1527 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1528 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1529 SSH_KEY_BITS_RESERVED) {
1530 options.server_key_bits =
1531 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1532 SSH_KEY_BITS_RESERVED;
1533 debug("Forcing server key to %d bits to make it differ from host key.",
1534 options.server_key_bits);
1541 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1542 (S_ISDIR(st.st_mode) == 0))
1543 fatal("Missing privilege separation directory: %s",
1544 _PATH_PRIVSEP_CHROOT_DIR);
1547 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1548 (st.st_uid != getuid () ||
1549 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1551 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1553 fatal("%s must be owned by root and not group or "
1554 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1557 /* Configuration looks good, so exit if in test mode. */
1562 * Clear out any supplemental groups we may have inherited. This
1563 * prevents inadvertent creation of files with bad modes (in the
1564 * portable version at least, it's certainly possible for PAM
1565 * to create a file, and we can't control the code in every
1566 * module which might be used).
1568 if (setgroups(0, NULL) < 0)
1569 debug("setgroups() failed: %.200s", strerror(errno));
1572 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1573 for (i = 0; i < rexec_argc; i++) {
1574 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1575 rexec_argv[i] = saved_argv[i];
1577 rexec_argv[rexec_argc] = "-R";
1578 rexec_argv[rexec_argc + 1] = NULL;
1581 /* Initialize the log (it is reinitialized below in case we forked). */
1582 if (debug_flag && (!inetd_flag || rexeced_flag))
1584 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1587 * If not in debugging mode, and not started from inetd, disconnect
1588 * from the controlling terminal, and fork. The original process
1591 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1594 #endif /* TIOCNOTTY */
1595 if (daemon(0, 0) < 0)
1596 fatal("daemon() failed: %.200s", strerror(errno));
1598 /* Disconnect from the controlling tty. */
1600 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1602 (void) ioctl(fd, TIOCNOTTY, NULL);
1605 #endif /* TIOCNOTTY */
1607 /* Reinitialize the log (because of the fork above). */
1608 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1610 /* Initialize the random number generator. */
1613 /* Chdir to the root directory so that the current disk can be
1614 unmounted if desired. */
1617 /* ignore SIGPIPE */
1618 signal(SIGPIPE, SIG_IGN);
1620 /* Get a connection, either from inetd or a listening TCP socket */
1622 server_accept_inetd(&sock_in, &sock_out);
1624 if ((options.protocol & SSH_PROTO_1) &&
1625 sensitive_data.server_key == NULL)
1626 generate_ephemeral_server_key();
1630 if (options.protocol & SSH_PROTO_1)
1631 generate_ephemeral_server_key();
1633 signal(SIGHUP, sighup_handler);
1634 signal(SIGCHLD, main_sigchld_handler);
1635 signal(SIGTERM, sigterm_handler);
1636 signal(SIGQUIT, sigterm_handler);
1639 * Write out the pid file after the sigterm handler
1640 * is setup and the listen sockets are bound
1643 FILE *f = fopen(options.pid_file, "w");
1646 error("Couldn't create pid file \"%s\": %s",
1647 options.pid_file, strerror(errno));
1649 fprintf(f, "%ld\n", (long) getpid());
1654 /* Accept a connection and return in a forked child */
1655 server_accept_loop(&sock_in, &sock_out,
1656 &newsock, config_s);
1659 /* This is the child processing a new connection. */
1660 setproctitle("%s", "[accepted]");
1663 * Create a new session and process group since the 4.4BSD
1664 * setlogin() affects the entire process group. We don't
1665 * want the child to be able to affect the parent.
1667 #if !defined(SSHD_ACQUIRES_CTTY)
1669 * If setsid is called, on some platforms sshd will later acquire a
1670 * controlling terminal which will result in "could not set
1671 * controlling tty" errors.
1673 if (!debug_flag && !inetd_flag && setsid() < 0)
1674 error("setsid: %.100s", strerror(errno));
1680 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1681 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1682 dup2(newsock, STDIN_FILENO);
1683 dup2(STDIN_FILENO, STDOUT_FILENO);
1684 if (startup_pipe == -1)
1685 close(REEXEC_STARTUP_PIPE_FD);
1687 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1689 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1691 if (startup_pipe != -1)
1692 close(startup_pipe);
1694 execv(rexec_argv[0], rexec_argv);
1696 /* Reexec has failed, fall back and continue */
1697 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1698 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1699 log_init(__progname, options.log_level,
1700 options.log_facility, log_stderr);
1703 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1705 close(REEXEC_CONFIG_PASS_FD);
1706 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1707 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1708 dup2(fd, STDIN_FILENO);
1709 dup2(fd, STDOUT_FILENO);
1710 if (fd > STDERR_FILENO)
1713 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1714 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1718 * Disable the key regeneration alarm. We will not regenerate the
1719 * key since we are no longer in a position to give it to anyone. We
1720 * will not restart on SIGHUP since it no longer makes sense.
1723 signal(SIGALRM, SIG_DFL);
1724 signal(SIGHUP, SIG_DFL);
1725 signal(SIGTERM, SIG_DFL);
1726 signal(SIGQUIT, SIG_DFL);
1727 signal(SIGCHLD, SIG_DFL);
1728 signal(SIGINT, SIG_DFL);
1731 * Register our connection. This turns encryption off because we do
1734 packet_set_connection(sock_in, sock_out);
1735 packet_set_server();
1737 /* Set SO_KEEPALIVE if requested. */
1738 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1739 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1740 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1742 if ((remote_port = get_remote_port()) < 0) {
1743 debug("get_remote_port failed");
1748 * We use get_canonical_hostname with usedns = 0 instead of
1749 * get_remote_ipaddr here so IP options will be checked.
1751 (void) get_canonical_hostname(0);
1753 * The rest of the code depends on the fact that
1754 * get_remote_ipaddr() caches the remote ip, even if
1755 * the socket goes away.
1757 remote_ip = get_remote_ipaddr();
1759 #ifdef SSH_AUDIT_EVENTS
1760 audit_connection_from(remote_ip, remote_port);
1763 /* Check whether logins are denied from this host. */
1764 if (packet_connection_is_on_socket()) {
1765 struct request_info req;
1767 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1770 if (!hosts_access(&req)) {
1771 debug("Connection refused by tcp wrapper");
1774 fatal("libwrap refuse returns");
1777 #endif /* LIBWRAP */
1779 /* Log the connection. */
1780 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1782 #ifdef USE_SECURITY_SESSION_API
1784 * Create a new security session for use by the new user login if
1785 * the current session is the root session or we are not launched
1786 * by inetd (eg: debugging mode or server mode). We do not
1787 * necessarily need to create a session if we are launched from
1788 * inetd because Panther xinetd will create a session for us.
1790 * The only case where this logic will fail is if there is an
1791 * inetd running in a non-root session which is not creating
1792 * new sessions for us. Then all the users will end up in the
1793 * same session (bad).
1795 * When the client exits, the session will be destroyed for us
1798 * We must create the session before any credentials are stored
1799 * (including AFS pags, which happens a few lines below).
1803 SecuritySessionId sid = 0;
1804 SessionAttributeBits sattrs = 0;
1806 err = SessionGetInfo(callerSecuritySession, &sid, &sattrs);
1808 error("SessionGetInfo() failed with error %.8X",
1811 debug("Current Session ID is %.8X / Session Attributes are %.8X",
1812 (unsigned) sid, (unsigned) sattrs);
1814 if (inetd_flag && !(sattrs & sessionIsRoot))
1815 debug("Running in inetd mode in a non-root session... "
1816 "assuming inetd created the session for us.");
1818 debug("Creating new security session...");
1819 err = SessionCreate(0, sessionHasTTY | sessionIsRemote);
1821 error("SessionCreate() failed with error %.8X",
1824 err = SessionGetInfo(callerSecuritySession, &sid,
1827 error("SessionGetInfo() failed with error %.8X",
1830 debug("New Session ID is %.8X / Session Attributes are %.8X",
1831 (unsigned) sid, (unsigned) sattrs);
1837 * We don't want to listen forever unless the other side
1838 * successfully authenticates itself. So we set up an alarm which is
1839 * cleared after successful authentication. A limit of zero
1840 * indicates no limit. Note that we don't set the alarm in debugging
1841 * mode; it is just annoying to have the server exit just when you
1842 * are about to discover the bug.
1844 signal(SIGALRM, grace_alarm_handler);
1846 alarm(options.login_grace_time);
1848 sshd_exchange_identification(sock_in, sock_out);
1849 #if defined(AFS_KRB5)
1850 /* If machine has AFS, set process authentication group. */
1855 #endif /* AFS || AFS_KRB5 */
1857 packet_set_nonblocking();
1859 /* allocate authentication context */
1860 authctxt = xcalloc(1, sizeof(*authctxt));
1862 authctxt->loginmsg = &loginmsg;
1864 /* XXX global for cleanup, access from other modules */
1865 the_authctxt = authctxt;
1867 /* prepare buffer to collect messages to display to user after login */
1868 buffer_init(&loginmsg);
1871 if (privsep_preauth(authctxt) == 1)
1874 /* perform the key exchange */
1875 /* authenticate user and start session */
1878 do_authentication2(authctxt);
1881 do_authentication(authctxt);
1884 * If we use privilege separation, the unprivileged child transfers
1885 * the current keystate and exits
1888 mm_send_keystate(pmonitor);
1894 * Cancel the alarm we set to limit the time taken for
1898 signal(SIGALRM, SIG_DFL);
1899 authctxt->authenticated = 1;
1900 if (startup_pipe != -1) {
1901 close(startup_pipe);
1905 #ifdef SSH_AUDIT_EVENTS
1906 audit_event(SSH_AUTH_SUCCESS);
1910 * In privilege separation, we fork another child and prepare
1911 * file descriptor passing.
1914 privsep_postauth(authctxt);
1915 /* the monitor process [priv] will not return */
1917 destroy_sensitive_data();
1920 /* Start session. */
1921 do_authenticated(authctxt);
1923 /* The connection has been terminated. */
1924 verbose("Closing connection to %.100s", remote_ip);
1927 if (options.use_pam)
1929 #endif /* USE_PAM */
1931 #ifdef SSH_AUDIT_EVENTS
1932 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1944 * Decrypt session_key_int using our private server key and private host key
1945 * (key with larger modulus first).
1948 ssh1_session_key(BIGNUM *session_key_int)
1952 if (BN_cmp(sensitive_data.server_key->rsa->n,
1953 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1954 /* Server key has bigger modulus. */
1955 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1956 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1957 SSH_KEY_BITS_RESERVED) {
1958 fatal("do_connection: %s: "
1959 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1960 get_remote_ipaddr(),
1961 BN_num_bits(sensitive_data.server_key->rsa->n),
1962 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1963 SSH_KEY_BITS_RESERVED);
1965 if (rsa_private_decrypt(session_key_int, session_key_int,
1966 sensitive_data.server_key->rsa) <= 0)
1968 if (rsa_private_decrypt(session_key_int, session_key_int,
1969 sensitive_data.ssh1_host_key->rsa) <= 0)
1972 /* Host key has bigger modulus (or they are equal). */
1973 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1974 BN_num_bits(sensitive_data.server_key->rsa->n) +
1975 SSH_KEY_BITS_RESERVED) {
1976 fatal("do_connection: %s: "
1977 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1978 get_remote_ipaddr(),
1979 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1980 BN_num_bits(sensitive_data.server_key->rsa->n),
1981 SSH_KEY_BITS_RESERVED);
1983 if (rsa_private_decrypt(session_key_int, session_key_int,
1984 sensitive_data.ssh1_host_key->rsa) < 0)
1986 if (rsa_private_decrypt(session_key_int, session_key_int,
1987 sensitive_data.server_key->rsa) < 0)
2000 BIGNUM *session_key_int;
2001 u_char session_key[SSH_SESSION_KEY_LENGTH];
2003 u_int cipher_type, auth_mask, protocol_flags;
2007 * Generate check bytes that the client must send back in the user
2008 * packet in order for it to be accepted; this is used to defy ip
2009 * spoofing attacks. Note that this only works against somebody
2010 * doing IP spoofing from a remote machine; any machine on the local
2011 * network can still see outgoing packets and catch the random
2012 * cookie. This only affects rhosts authentication, and this is one
2013 * of the reasons why it is inherently insecure.
2015 for (i = 0; i < 8; i++) {
2018 cookie[i] = rnd & 0xff;
2023 * Send our public key. We include in the packet 64 bits of random
2024 * data that must be matched in the reply in order to prevent IP
2027 packet_start(SSH_SMSG_PUBLIC_KEY);
2028 for (i = 0; i < 8; i++)
2029 packet_put_char(cookie[i]);
2031 /* Store our public server RSA key. */
2032 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2033 packet_put_bignum(sensitive_data.server_key->rsa->e);
2034 packet_put_bignum(sensitive_data.server_key->rsa->n);
2036 /* Store our public host RSA key. */
2037 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2038 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2039 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2041 /* Put protocol flags. */
2042 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2044 /* Declare which ciphers we support. */
2045 packet_put_int(cipher_mask_ssh1(0));
2047 /* Declare supported authentication types. */
2049 if (options.rhosts_rsa_authentication)
2050 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2051 if (options.rsa_authentication)
2052 auth_mask |= 1 << SSH_AUTH_RSA;
2053 if (options.challenge_response_authentication == 1)
2054 auth_mask |= 1 << SSH_AUTH_TIS;
2055 if (options.password_authentication)
2056 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2057 packet_put_int(auth_mask);
2059 /* Send the packet and wait for it to be sent. */
2061 packet_write_wait();
2063 debug("Sent %d bit server key and %d bit host key.",
2064 BN_num_bits(sensitive_data.server_key->rsa->n),
2065 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2067 /* Read clients reply (cipher type and session key). */
2068 packet_read_expect(SSH_CMSG_SESSION_KEY);
2070 /* Get cipher type and check whether we accept this. */
2071 cipher_type = packet_get_char();
2073 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2074 packet_disconnect("Warning: client selects unsupported cipher.");
2076 /* Get check bytes from the packet. These must match those we
2077 sent earlier with the public key packet. */
2078 for (i = 0; i < 8; i++)
2079 if (cookie[i] != packet_get_char())
2080 packet_disconnect("IP Spoofing check bytes do not match.");
2082 debug("Encryption type: %.200s", cipher_name(cipher_type));
2084 /* Get the encrypted integer. */
2085 if ((session_key_int = BN_new()) == NULL)
2086 fatal("do_ssh1_kex: BN_new failed");
2087 packet_get_bignum(session_key_int);
2089 protocol_flags = packet_get_int();
2090 packet_set_protocol_flags(protocol_flags);
2093 /* Decrypt session_key_int using host/server keys */
2094 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2097 * Extract session key from the decrypted integer. The key is in the
2098 * least significant 256 bits of the integer; the first byte of the
2099 * key is in the highest bits.
2102 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2103 len = BN_num_bytes(session_key_int);
2104 if (len < 0 || (u_int)len > sizeof(session_key)) {
2105 error("do_ssh1_kex: bad session key len from %s: "
2106 "session_key_int %d > sizeof(session_key) %lu",
2107 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2110 memset(session_key, 0, sizeof(session_key));
2111 BN_bn2bin(session_key_int,
2112 session_key + sizeof(session_key) - len);
2114 derive_ssh1_session_id(
2115 sensitive_data.ssh1_host_key->rsa->n,
2116 sensitive_data.server_key->rsa->n,
2117 cookie, session_id);
2119 * Xor the first 16 bytes of the session key with the
2122 for (i = 0; i < 16; i++)
2123 session_key[i] ^= session_id[i];
2127 int bytes = BN_num_bytes(session_key_int);
2128 u_char *buf = xmalloc(bytes);
2131 logit("do_connection: generating a fake encryption key");
2132 BN_bn2bin(session_key_int, buf);
2134 MD5_Update(&md, buf, bytes);
2135 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2136 MD5_Final(session_key, &md);
2138 MD5_Update(&md, session_key, 16);
2139 MD5_Update(&md, buf, bytes);
2140 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2141 MD5_Final(session_key + 16, &md);
2142 memset(buf, 0, bytes);
2144 for (i = 0; i < 16; i++)
2145 session_id[i] = session_key[i] ^ session_key[i + 16];
2147 /* Destroy the private and public keys. No longer. */
2148 destroy_sensitive_data();
2151 mm_ssh1_session_id(session_id);
2153 /* Destroy the decrypted integer. It is no longer needed. */
2154 BN_clear_free(session_key_int);
2156 /* Set the session key. From this on all communications will be encrypted. */
2157 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2159 /* Destroy our copy of the session key. It is no longer needed. */
2160 memset(session_key, 0, sizeof(session_key));
2162 debug("Received session key; encryption turned on.");
2164 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2165 packet_start(SSH_SMSG_SUCCESS);
2167 packet_write_wait();
2171 * SSH2 key exchange: diffie-hellman-group1-sha1
2179 debug ("MYFLAG IS %d", myflag);
2180 if (options.ciphers != NULL) {
2181 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2182 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2183 } else if (options.none_enabled == 1) {
2184 debug ("WARNING: None cipher enabled");
2185 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2186 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE;
2188 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2189 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2190 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2191 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2193 if (options.macs != NULL) {
2194 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2195 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2197 if (options.compression == COMP_NONE) {
2198 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2199 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2200 } else if (options.compression == COMP_DELAYED) {
2201 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2202 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2205 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2211 char *newstr = NULL;
2212 orig = myproposal[PROPOSAL_KEX_ALGS];
2215 * If we don't have a host key, then there's no point advertising
2216 * the other key exchange algorithms
2219 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
2222 if (options.gss_keyex)
2223 gss = ssh_gssapi_server_mechanisms();
2228 xasprintf(&newstr, "%s,%s", gss, orig);
2235 * If we've got GSSAPI mechanisms, then we've got the 'null' host
2236 * key alg, but we can't tell people about it unless its the only
2237 * host key algorithm we support
2239 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
2240 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
2243 myproposal[PROPOSAL_KEX_ALGS] = newstr;
2245 fatal("No supported key exchange algorithms");
2249 /* start key exchange */
2250 /* start key exchange */
2251 kex = kex_setup(myproposal);
2252 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2253 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2254 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2255 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2257 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
2258 kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
2259 kex->kex[KEX_GSS_GEX_SHA1] = kexgss_server;
2262 kex->client_version_string=client_version_string;
2263 kex->server_version_string=server_version_string;
2264 kex->load_host_key=&get_hostkey_by_type;
2265 kex->host_key_index=&get_hostkey_index;
2269 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2271 session_id2 = kex->session_id;
2272 session_id2_len = kex->session_id_len;
2275 /* send 1st encrypted/maced/compressed message */
2276 packet_start(SSH2_MSG_IGNORE);
2277 packet_put_cstring("markus");
2279 packet_write_wait();
2284 /* server specific fatal cleanup */
2289 do_cleanup(the_authctxt);
2290 #ifdef SSH_AUDIT_EVENTS
2291 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2292 if (!use_privsep || mm_is_monitor())
2293 audit_event(SSH_CONNECTION_ABANDON);