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);
481 compat_datafellows(remote_version);
483 if (datafellows & SSH_BUG_PROBE) {
484 logit("probed from %s with %s. Don't panic.",
485 get_remote_ipaddr(), client_version_string);
489 if (datafellows & SSH_BUG_SCANNER) {
490 logit("scanned from %s with %s. Don't panic.",
491 get_remote_ipaddr(), client_version_string);
496 switch (remote_major) {
498 if (remote_minor == 99) {
499 if (options.protocol & SSH_PROTO_2)
505 if (!(options.protocol & SSH_PROTO_1)) {
509 if (remote_minor < 3) {
510 packet_disconnect("Your ssh version is too old and "
511 "is no longer supported. Please install a newer version.");
512 } else if (remote_minor == 3) {
513 /* note that this disables agent-forwarding */
518 if (options.protocol & SSH_PROTO_2) {
527 chop(server_version_string);
528 debug("Local version string %.200s", server_version_string);
531 s = "Protocol major versions differ.\n";
532 (void) atomicio(vwrite, sock_out, s, strlen(s));
535 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
537 server_version_string, client_version_string);
542 /* Destroy the host and server keys. They will no longer be needed. */
544 destroy_sensitive_data(void)
548 if (sensitive_data.server_key) {
549 key_free(sensitive_data.server_key);
550 sensitive_data.server_key = NULL;
552 for (i = 0; i < options.num_host_key_files; i++) {
553 if (sensitive_data.host_keys[i]) {
554 key_free(sensitive_data.host_keys[i]);
555 sensitive_data.host_keys[i] = NULL;
558 sensitive_data.ssh1_host_key = NULL;
559 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
562 /* Demote private to public keys for network child */
564 demote_sensitive_data(void)
569 if (sensitive_data.server_key) {
570 tmp = key_demote(sensitive_data.server_key);
571 key_free(sensitive_data.server_key);
572 sensitive_data.server_key = tmp;
575 for (i = 0; i < options.num_host_key_files; i++) {
576 if (sensitive_data.host_keys[i]) {
577 tmp = key_demote(sensitive_data.host_keys[i]);
578 key_free(sensitive_data.host_keys[i]);
579 sensitive_data.host_keys[i] = tmp;
580 if (tmp->type == KEY_RSA1)
581 sensitive_data.ssh1_host_key = tmp;
585 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
589 privsep_preauth_child(void)
595 /* Enable challenge-response authentication for privilege separation */
596 privsep_challenge_enable();
598 for (i = 0; i < 256; i++)
599 rnd[i] = arc4random();
600 RAND_seed(rnd, sizeof(rnd));
602 /* Demote the private keys to public keys. */
603 demote_sensitive_data();
605 /* Change our root directory */
606 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
607 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
609 if (chdir("/") == -1)
610 fatal("chdir(\"/\"): %s", strerror(errno));
612 /* Drop our privileges */
613 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
614 (u_int)privsep_pw->pw_gid);
616 /* XXX not ready, too heavy after chroot */
617 do_setusercontext(privsep_pw);
619 gidset[0] = privsep_pw->pw_gid;
620 if (setgroups(1, gidset) < 0)
621 fatal("setgroups: %.100s", strerror(errno));
622 permanently_set_uid(privsep_pw);
627 privsep_preauth(Authctxt *authctxt)
632 /* Set up unprivileged child process to deal with network data */
633 pmonitor = monitor_init();
634 /* Store a pointer to the kex for later rekeying */
635 pmonitor->m_pkex = &xxx_kex;
639 fatal("fork of unprivileged child failed");
640 } else if (pid != 0) {
641 debug2("Network child is on pid %ld", (long)pid);
643 close(pmonitor->m_recvfd);
644 pmonitor->m_pid = pid;
645 monitor_child_preauth(authctxt, pmonitor);
646 close(pmonitor->m_sendfd);
649 monitor_sync(pmonitor);
651 /* Wait for the child's exit status */
652 while (waitpid(pid, &status, 0) < 0)
659 close(pmonitor->m_sendfd);
661 /* Demote the child */
662 if (getuid() == 0 || geteuid() == 0)
663 privsep_preauth_child();
664 setproctitle("%s", "[net]");
670 privsep_postauth(Authctxt *authctxt)
672 #ifdef DISABLE_FD_PASSING
675 if (authctxt->pw->pw_uid == 0 || options.use_login) {
677 /* File descriptor passing is broken or root login */
682 /* New socket pair */
683 monitor_reinit(pmonitor);
685 pmonitor->m_pid = fork();
686 if (pmonitor->m_pid == -1)
687 fatal("fork of unprivileged child failed");
688 else if (pmonitor->m_pid != 0) {
689 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
690 close(pmonitor->m_recvfd);
691 buffer_clear(&loginmsg);
692 monitor_child_postauth(pmonitor);
698 close(pmonitor->m_sendfd);
700 /* Demote the private keys to public keys. */
701 demote_sensitive_data();
703 /* Drop privileges */
704 do_setusercontext(authctxt->pw);
707 /* It is safe now to apply the key state */
708 monitor_apply_keystate(pmonitor);
711 * Tell the packet layer that authentication was successful, since
712 * this information is not part of the key state.
714 packet_set_authenticated();
718 list_hostkey_types(void)
726 for (i = 0; i < options.num_host_key_files; i++) {
727 Key *key = sensitive_data.host_keys[i];
733 if (buffer_len(&b) > 0)
734 buffer_append(&b, ",", 1);
735 p = key_ssh_name(key);
736 buffer_append(&b, p, strlen(p));
740 buffer_append(&b, "\0", 1);
741 ret = xstrdup(buffer_ptr(&b));
743 debug("list_hostkey_types: %s", ret);
748 get_hostkey_by_type(int type)
752 for (i = 0; i < options.num_host_key_files; i++) {
753 Key *key = sensitive_data.host_keys[i];
754 if (key != NULL && key->type == type)
761 get_hostkey_by_index(int ind)
763 if (ind < 0 || ind >= options.num_host_key_files)
765 return (sensitive_data.host_keys[ind]);
769 get_hostkey_index(Key *key)
773 for (i = 0; i < options.num_host_key_files; i++) {
774 if (key == sensitive_data.host_keys[i])
781 * returns 1 if connection should be dropped, 0 otherwise.
782 * dropping starts at connection #max_startups_begin with a probability
783 * of (max_startups_rate/100). the probability increases linearly until
784 * all connections are dropped for startups > max_startups
787 drop_connection(int startups)
791 if (startups < options.max_startups_begin)
793 if (startups >= options.max_startups)
795 if (options.max_startups_rate == 100)
798 p = 100 - options.max_startups_rate;
799 p *= startups - options.max_startups_begin;
800 p /= options.max_startups - options.max_startups_begin;
801 p += options.max_startups_rate;
802 r = arc4random() % 100;
804 debug("drop_connection: p %d, r %d", p, r);
805 return (r < p) ? 1 : 0;
811 fprintf(stderr, "%s, %s\n",
812 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
814 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
815 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
821 send_rexec_state(int fd, Buffer *conf)
825 debug3("%s: entering fd = %d config len %d", __func__, fd,
829 * Protocol from reexec master to child:
830 * string configuration
831 * u_int ephemeral_key_follows
832 * bignum e (only if ephemeral_key_follows == 1)
838 * string rngseed (only if OpenSSL is not self-seeded)
841 buffer_put_cstring(&m, buffer_ptr(conf));
843 if (sensitive_data.server_key != NULL &&
844 sensitive_data.server_key->type == KEY_RSA1) {
845 buffer_put_int(&m, 1);
846 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
847 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
848 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
849 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
850 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
851 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
853 buffer_put_int(&m, 0);
855 #ifndef OPENSSL_PRNG_ONLY
856 rexec_send_rng_seed(&m);
859 if (ssh_msg_send(fd, 0, &m) == -1)
860 fatal("%s: ssh_msg_send failed", __func__);
864 debug3("%s: done", __func__);
868 recv_rexec_state(int fd, Buffer *conf)
874 debug3("%s: entering fd = %d", __func__, fd);
878 if (ssh_msg_recv(fd, &m) == -1)
879 fatal("%s: ssh_msg_recv failed", __func__);
880 if (buffer_get_char(&m) != 0)
881 fatal("%s: rexec version mismatch", __func__);
883 cp = buffer_get_string(&m, &len);
885 buffer_append(conf, cp, len + 1);
888 if (buffer_get_int(&m)) {
889 if (sensitive_data.server_key != NULL)
890 key_free(sensitive_data.server_key);
891 sensitive_data.server_key = key_new_private(KEY_RSA1);
892 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
893 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
894 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
895 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
896 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
897 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
898 rsa_generate_additional_parameters(
899 sensitive_data.server_key->rsa);
902 #ifndef OPENSSL_PRNG_ONLY
903 rexec_recv_rng_seed(&m);
908 debug3("%s: done", __func__);
911 /* Accept a connection from inetd */
913 server_accept_inetd(int *sock_in, int *sock_out)
919 close(REEXEC_CONFIG_PASS_FD);
920 *sock_in = *sock_out = dup(STDIN_FILENO);
922 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
923 close(REEXEC_STARTUP_PIPE_FD);
926 *sock_in = dup(STDIN_FILENO);
927 *sock_out = dup(STDOUT_FILENO);
930 * We intentionally do not close the descriptors 0, 1, and 2
931 * as our code for setting the descriptors won't work if
932 * ttyfd happens to be one of those.
934 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
935 dup2(fd, STDIN_FILENO);
936 dup2(fd, STDOUT_FILENO);
937 if (fd > STDOUT_FILENO)
940 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
944 * Listen for TCP connections
949 int ret, listen_sock, on = 1;
951 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
953 int socksizelen = sizeof(int);
955 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
956 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
958 if (num_listen_socks >= MAX_LISTEN_SOCKS)
959 fatal("Too many listen sockets. "
960 "Enlarge MAX_LISTEN_SOCKS");
961 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
962 ntop, sizeof(ntop), strport, sizeof(strport),
963 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
964 error("getnameinfo failed: %.100s",
965 (ret != EAI_SYSTEM) ? gai_strerror(ret) :
969 /* Create socket for listening. */
970 listen_sock = socket(ai->ai_family, ai->ai_socktype,
972 if (listen_sock < 0) {
973 /* kernel may not support ipv6 */
974 verbose("socket: %.100s", strerror(errno));
977 if (set_nonblock(listen_sock) == -1) {
982 * Set socket options.
983 * Allow local port reuse in TIME_WAIT.
985 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
986 &on, sizeof(on)) == -1)
987 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
989 debug("Bind to port %s on %s.", strport, ntop);
991 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF,
992 &socksize, &socksizelen);
993 debug("Server TCP RWIN socket size: %d", socksize);
994 debug("HPN Buffer Size: %d", options.hpn_buffer_size);
996 /* Bind the socket to the desired port. */
997 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
998 error("Bind to port %s on %s failed: %.200s.",
999 strport, ntop, strerror(errno));
1003 listen_socks[num_listen_socks] = listen_sock;
1006 /* Start listening on the port. */
1007 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1008 fatal("listen on [%s]:%s: %.100s",
1009 ntop, strport, strerror(errno));
1010 logit("Server listening on %s port %s.", ntop, strport);
1012 freeaddrinfo(options.listen_addrs);
1014 if (!num_listen_socks)
1015 fatal("Cannot bind any address.");
1019 * The main TCP accept loop. Note that, for the non-debug case, returns
1020 * from this function are in a forked subprocess.
1023 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1026 int i, j, ret, maxfd;
1027 int key_used = 0, startups = 0;
1028 int startup_p[2] = { -1 , -1 };
1029 struct sockaddr_storage from;
1033 /* setup fd set for accept */
1036 for (i = 0; i < num_listen_socks; i++)
1037 if (listen_socks[i] > maxfd)
1038 maxfd = listen_socks[i];
1039 /* pipes connected to unauthenticated childs */
1040 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1041 for (i = 0; i < options.max_startups; i++)
1042 startup_pipes[i] = -1;
1045 * Stay listening for connections until the system crashes or
1046 * the daemon is killed with a signal.
1049 if (received_sighup)
1053 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1056 for (i = 0; i < num_listen_socks; i++)
1057 FD_SET(listen_socks[i], fdset);
1058 for (i = 0; i < options.max_startups; i++)
1059 if (startup_pipes[i] != -1)
1060 FD_SET(startup_pipes[i], fdset);
1062 /* Wait in select until there is a connection. */
1063 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1064 if (ret < 0 && errno != EINTR)
1065 error("select: %.100s", strerror(errno));
1066 if (received_sigterm) {
1067 logit("Received signal %d; terminating.",
1068 (int) received_sigterm);
1069 close_listen_socks();
1070 unlink(options.pid_file);
1073 if (key_used && key_do_regen) {
1074 generate_ephemeral_server_key();
1081 for (i = 0; i < options.max_startups; i++)
1082 if (startup_pipes[i] != -1 &&
1083 FD_ISSET(startup_pipes[i], fdset)) {
1085 * the read end of the pipe is ready
1086 * if the child has closed the pipe
1087 * after successful authentication
1088 * or if the child has died
1090 close(startup_pipes[i]);
1091 startup_pipes[i] = -1;
1094 for (i = 0; i < num_listen_socks; i++) {
1095 if (!FD_ISSET(listen_socks[i], fdset))
1097 fromlen = sizeof(from);
1098 *newsock = accept(listen_socks[i],
1099 (struct sockaddr *)&from, &fromlen);
1101 if (errno != EINTR && errno != EWOULDBLOCK)
1102 error("accept: %.100s", strerror(errno));
1105 if (unset_nonblock(*newsock) == -1) {
1109 if (drop_connection(startups) == 1) {
1110 debug("drop connection #%d", startups);
1114 if (pipe(startup_p) == -1) {
1119 if (rexec_flag && socketpair(AF_UNIX,
1120 SOCK_STREAM, 0, config_s) == -1) {
1121 error("reexec socketpair: %s",
1124 close(startup_p[0]);
1125 close(startup_p[1]);
1129 for (j = 0; j < options.max_startups; j++)
1130 if (startup_pipes[j] == -1) {
1131 startup_pipes[j] = startup_p[0];
1132 if (maxfd < startup_p[0])
1133 maxfd = startup_p[0];
1139 * Got connection. Fork a child to handle it, unless
1140 * we are in debugging mode.
1144 * In debugging mode. Close the listening
1145 * socket, and start processing the
1146 * connection without forking.
1148 debug("Server will not fork when running in debugging mode.");
1149 close_listen_socks();
1150 *sock_in = *newsock;
1151 *sock_out = *newsock;
1152 close(startup_p[0]);
1153 close(startup_p[1]);
1157 send_rexec_state(config_s[0],
1165 * Normal production daemon. Fork, and have
1166 * the child process the connection. The
1167 * parent continues listening.
1169 platform_pre_fork();
1170 if ((pid = fork()) == 0) {
1172 * Child. Close the listening and
1173 * max_startup sockets. Start using
1174 * the accepted socket. Reinitialize
1175 * logging (since our pid has changed).
1176 * We break out of the loop to handle
1179 platform_post_fork_child();
1180 startup_pipe = startup_p[1];
1181 close_startup_pipes();
1182 close_listen_socks();
1183 *sock_in = *newsock;
1184 *sock_out = *newsock;
1185 log_init(__progname,
1187 options.log_facility,
1194 /* Parent. Stay in the loop. */
1195 platform_post_fork_parent(pid);
1197 error("fork: %.100s", strerror(errno));
1199 debug("Forked child %ld.", (long)pid);
1201 close(startup_p[1]);
1204 send_rexec_state(config_s[0], &cfg);
1210 * Mark that the key has been used (it
1211 * was "given" to the child).
1213 if ((options.protocol & SSH_PROTO_1) &&
1215 /* Schedule server key regeneration alarm. */
1216 signal(SIGALRM, key_regeneration_alarm);
1217 alarm(options.key_regeneration_time);
1224 * Ensure that our random state differs
1225 * from that of the child
1230 /* child process check (or debug mode) */
1231 if (num_listen_socks < 0)
1238 * Main program for the daemon.
1241 main(int ac, char **av)
1243 extern char *optarg;
1246 int sock_in = -1, sock_out = -1, newsock = -1;
1247 const char *remote_ip;
1250 int config_s[2] = { -1 , -1 };
1254 #ifdef HAVE_SECUREWARE
1255 (void)set_auth_parameters(ac, av);
1257 __progname = ssh_get_progname(av[0]);
1260 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1263 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1264 for (i = 0; i < ac; i++)
1265 saved_argv[i] = xstrdup(av[i]);
1266 saved_argv[i] = NULL;
1268 #ifndef HAVE_SETPROCTITLE
1269 /* Prepare for later setproctitle emulation */
1270 compat_init_setproctitle(ac, av);
1274 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1275 debug("setgroups(): %.200s", strerror(errno));
1277 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1280 /* Initialize configuration options to their default values. */
1281 initialize_server_options(&options);
1283 /* Parse command-line arguments. */
1284 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
1287 options.address_family = AF_INET;
1290 options.address_family = AF_INET6;
1293 config_file_name = optarg;
1296 if (debug_flag == 0) {
1298 options.log_level = SYSLOG_LEVEL_DEBUG1;
1299 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1300 options.log_level++;
1322 options.log_level = SYSLOG_LEVEL_QUIET;
1325 options.server_key_bits = (int)strtonum(optarg, 256,
1329 options.ports_from_cmdline = 1;
1330 if (options.num_ports >= MAX_PORTS) {
1331 fprintf(stderr, "too many ports.\n");
1334 options.ports[options.num_ports++] = a2port(optarg);
1335 if (options.ports[options.num_ports-1] == 0) {
1336 fprintf(stderr, "Bad port number.\n");
1341 if ((options.login_grace_time = convtime(optarg)) == -1) {
1342 fprintf(stderr, "Invalid login grace time.\n");
1347 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1348 fprintf(stderr, "Invalid key regeneration interval.\n");
1353 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1354 fprintf(stderr, "too many host keys.\n");
1357 options.host_key_files[options.num_host_key_files++] = optarg;
1363 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1364 if (utmp_len > MAXHOSTNAMELEN) {
1365 fprintf(stderr, "Invalid utmp length.\n");
1370 line = xstrdup(optarg);
1371 if (process_server_config_line(&options, line,
1372 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1382 if (rexeced_flag || inetd_flag)
1384 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1385 fatal("sshd re-exec requires execution with an absolute path");
1387 closefrom(REEXEC_MIN_FREE_FD);
1389 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1391 SSLeay_add_all_algorithms();
1394 * Force logging to stderr until we have loaded the private host
1395 * key (unless started from inetd)
1397 log_init(__progname,
1398 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1399 SYSLOG_LEVEL_INFO : options.log_level,
1400 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1401 SYSLOG_FACILITY_AUTH : options.log_facility,
1402 log_stderr || !inetd_flag);
1405 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1406 * root's environment
1408 if (getenv("KRB5CCNAME") != NULL)
1409 unsetenv("KRB5CCNAME");
1412 /* Cray can define user privs drop all privs now!
1413 * Not needed on PRIV_SU systems!
1418 sensitive_data.server_key = NULL;
1419 sensitive_data.ssh1_host_key = NULL;
1420 sensitive_data.have_ssh1_key = 0;
1421 sensitive_data.have_ssh2_key = 0;
1423 /* Fetch our configuration */
1426 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1428 load_server_config(config_file_name, &cfg);
1430 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1431 &cfg, NULL, NULL, NULL);
1435 /* Fill in default values for those options not explicitly set. */
1436 fill_default_server_options(&options);
1438 /* challenge-response is implemented via keyboard interactive */
1439 if (options.challenge_response_authentication)
1440 options.kbd_interactive_authentication = 1;
1442 /* set default channel AF */
1443 channel_set_af(options.address_family);
1445 /* Check that there are no remaining arguments. */
1447 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1451 debug("sshd version %.100s", SSH_RELEASE);
1453 /* Store privilege separation user for later use if required. */
1454 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1455 if (use_privsep || options.kerberos_authentication)
1456 fatal("Privilege separation user %s does not exist",
1459 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1460 privsep_pw = pwcopy(privsep_pw);
1461 xfree(privsep_pw->pw_passwd);
1462 privsep_pw->pw_passwd = xstrdup("*");
1466 /* load private host keys */
1467 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1469 for (i = 0; i < options.num_host_key_files; i++)
1470 sensitive_data.host_keys[i] = NULL;
1472 for (i = 0; i < options.num_host_key_files; i++) {
1473 key = key_load_private(options.host_key_files[i], "", NULL);
1474 sensitive_data.host_keys[i] = key;
1476 error("Could not load host key: %s",
1477 options.host_key_files[i]);
1478 sensitive_data.host_keys[i] = NULL;
1481 switch (key->type) {
1483 sensitive_data.ssh1_host_key = key;
1484 sensitive_data.have_ssh1_key = 1;
1488 sensitive_data.have_ssh2_key = 1;
1491 debug("private host key: #%d type %d %s", i, key->type,
1494 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1495 logit("Disabling protocol version 1. Could not load host key");
1496 options.protocol &= ~SSH_PROTO_1;
1499 /* The GSSAPI key exchange can run without a host key */
1500 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1501 logit("Disabling protocol version 2. Could not load host key");
1502 options.protocol &= ~SSH_PROTO_2;
1505 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1506 logit("sshd: no hostkeys available -- exiting.");
1510 /* Check certain values for sanity. */
1511 if (options.protocol & SSH_PROTO_1) {
1512 if (options.server_key_bits < 512 ||
1513 options.server_key_bits > 32768) {
1514 fprintf(stderr, "Bad server key size.\n");
1518 * Check that server and host key lengths differ sufficiently. This
1519 * is necessary to make double encryption work with rsaref. Oh, I
1520 * hate software patents. I dont know if this can go? Niels
1522 if (options.server_key_bits >
1523 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1524 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1525 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1526 SSH_KEY_BITS_RESERVED) {
1527 options.server_key_bits =
1528 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1529 SSH_KEY_BITS_RESERVED;
1530 debug("Forcing server key to %d bits to make it differ from host key.",
1531 options.server_key_bits);
1538 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1539 (S_ISDIR(st.st_mode) == 0))
1540 fatal("Missing privilege separation directory: %s",
1541 _PATH_PRIVSEP_CHROOT_DIR);
1544 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1545 (st.st_uid != getuid () ||
1546 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1548 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1550 fatal("%s must be owned by root and not group or "
1551 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1554 /* Configuration looks good, so exit if in test mode. */
1559 * Clear out any supplemental groups we may have inherited. This
1560 * prevents inadvertent creation of files with bad modes (in the
1561 * portable version at least, it's certainly possible for PAM
1562 * to create a file, and we can't control the code in every
1563 * module which might be used).
1565 if (setgroups(0, NULL) < 0)
1566 debug("setgroups() failed: %.200s", strerror(errno));
1569 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1570 for (i = 0; i < rexec_argc; i++) {
1571 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1572 rexec_argv[i] = saved_argv[i];
1574 rexec_argv[rexec_argc] = "-R";
1575 rexec_argv[rexec_argc + 1] = NULL;
1578 /* Initialize the log (it is reinitialized below in case we forked). */
1579 if (debug_flag && (!inetd_flag || rexeced_flag))
1581 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1584 * If not in debugging mode, and not started from inetd, disconnect
1585 * from the controlling terminal, and fork. The original process
1588 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1591 #endif /* TIOCNOTTY */
1592 if (daemon(0, 0) < 0)
1593 fatal("daemon() failed: %.200s", strerror(errno));
1595 /* Disconnect from the controlling tty. */
1597 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1599 (void) ioctl(fd, TIOCNOTTY, NULL);
1602 #endif /* TIOCNOTTY */
1604 /* Reinitialize the log (because of the fork above). */
1605 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1607 /* Initialize the random number generator. */
1610 /* Chdir to the root directory so that the current disk can be
1611 unmounted if desired. */
1614 /* ignore SIGPIPE */
1615 signal(SIGPIPE, SIG_IGN);
1617 /* Get a connection, either from inetd or a listening TCP socket */
1619 server_accept_inetd(&sock_in, &sock_out);
1621 if ((options.protocol & SSH_PROTO_1) &&
1622 sensitive_data.server_key == NULL)
1623 generate_ephemeral_server_key();
1627 if (options.protocol & SSH_PROTO_1)
1628 generate_ephemeral_server_key();
1630 signal(SIGHUP, sighup_handler);
1631 signal(SIGCHLD, main_sigchld_handler);
1632 signal(SIGTERM, sigterm_handler);
1633 signal(SIGQUIT, sigterm_handler);
1636 * Write out the pid file after the sigterm handler
1637 * is setup and the listen sockets are bound
1640 FILE *f = fopen(options.pid_file, "w");
1643 error("Couldn't create pid file \"%s\": %s",
1644 options.pid_file, strerror(errno));
1646 fprintf(f, "%ld\n", (long) getpid());
1651 /* Accept a connection and return in a forked child */
1652 server_accept_loop(&sock_in, &sock_out,
1653 &newsock, config_s);
1656 /* This is the child processing a new connection. */
1657 setproctitle("%s", "[accepted]");
1660 * Create a new session and process group since the 4.4BSD
1661 * setlogin() affects the entire process group. We don't
1662 * want the child to be able to affect the parent.
1664 #if !defined(SSHD_ACQUIRES_CTTY)
1666 * If setsid is called, on some platforms sshd will later acquire a
1667 * controlling terminal which will result in "could not set
1668 * controlling tty" errors.
1670 if (!debug_flag && !inetd_flag && setsid() < 0)
1671 error("setsid: %.100s", strerror(errno));
1677 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1678 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1679 dup2(newsock, STDIN_FILENO);
1680 dup2(STDIN_FILENO, STDOUT_FILENO);
1681 if (startup_pipe == -1)
1682 close(REEXEC_STARTUP_PIPE_FD);
1684 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1686 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1688 if (startup_pipe != -1)
1689 close(startup_pipe);
1691 execv(rexec_argv[0], rexec_argv);
1693 /* Reexec has failed, fall back and continue */
1694 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1695 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1696 log_init(__progname, options.log_level,
1697 options.log_facility, log_stderr);
1700 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1702 close(REEXEC_CONFIG_PASS_FD);
1703 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1704 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1705 dup2(fd, STDIN_FILENO);
1706 dup2(fd, STDOUT_FILENO);
1707 if (fd > STDERR_FILENO)
1710 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1711 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1715 * Disable the key regeneration alarm. We will not regenerate the
1716 * key since we are no longer in a position to give it to anyone. We
1717 * will not restart on SIGHUP since it no longer makes sense.
1720 signal(SIGALRM, SIG_DFL);
1721 signal(SIGHUP, SIG_DFL);
1722 signal(SIGTERM, SIG_DFL);
1723 signal(SIGQUIT, SIG_DFL);
1724 signal(SIGCHLD, SIG_DFL);
1725 signal(SIGINT, SIG_DFL);
1728 * Register our connection. This turns encryption off because we do
1731 packet_set_connection(sock_in, sock_out);
1732 packet_set_server();
1734 /* Set SO_KEEPALIVE if requested. */
1735 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1736 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1737 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1739 if ((remote_port = get_remote_port()) < 0) {
1740 debug("get_remote_port failed");
1745 * We use get_canonical_hostname with usedns = 0 instead of
1746 * get_remote_ipaddr here so IP options will be checked.
1748 (void) get_canonical_hostname(0);
1750 * The rest of the code depends on the fact that
1751 * get_remote_ipaddr() caches the remote ip, even if
1752 * the socket goes away.
1754 remote_ip = get_remote_ipaddr();
1756 #ifdef SSH_AUDIT_EVENTS
1757 audit_connection_from(remote_ip, remote_port);
1760 /* Check whether logins are denied from this host. */
1761 if (packet_connection_is_on_socket()) {
1762 struct request_info req;
1764 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1767 if (!hosts_access(&req)) {
1768 debug("Connection refused by tcp wrapper");
1771 fatal("libwrap refuse returns");
1774 #endif /* LIBWRAP */
1776 /* Log the connection. */
1777 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1779 #ifdef USE_SECURITY_SESSION_API
1781 * Create a new security session for use by the new user login if
1782 * the current session is the root session or we are not launched
1783 * by inetd (eg: debugging mode or server mode). We do not
1784 * necessarily need to create a session if we are launched from
1785 * inetd because Panther xinetd will create a session for us.
1787 * The only case where this logic will fail is if there is an
1788 * inetd running in a non-root session which is not creating
1789 * new sessions for us. Then all the users will end up in the
1790 * same session (bad).
1792 * When the client exits, the session will be destroyed for us
1795 * We must create the session before any credentials are stored
1796 * (including AFS pags, which happens a few lines below).
1800 SecuritySessionId sid = 0;
1801 SessionAttributeBits sattrs = 0;
1803 err = SessionGetInfo(callerSecuritySession, &sid, &sattrs);
1805 error("SessionGetInfo() failed with error %.8X",
1808 debug("Current Session ID is %.8X / Session Attributes are %.8X",
1809 (unsigned) sid, (unsigned) sattrs);
1811 if (inetd_flag && !(sattrs & sessionIsRoot))
1812 debug("Running in inetd mode in a non-root session... "
1813 "assuming inetd created the session for us.");
1815 debug("Creating new security session...");
1816 err = SessionCreate(0, sessionHasTTY | sessionIsRemote);
1818 error("SessionCreate() failed with error %.8X",
1821 err = SessionGetInfo(callerSecuritySession, &sid,
1824 error("SessionGetInfo() failed with error %.8X",
1827 debug("New Session ID is %.8X / Session Attributes are %.8X",
1828 (unsigned) sid, (unsigned) sattrs);
1834 * We don't want to listen forever unless the other side
1835 * successfully authenticates itself. So we set up an alarm which is
1836 * cleared after successful authentication. A limit of zero
1837 * indicates no limit. Note that we don't set the alarm in debugging
1838 * mode; it is just annoying to have the server exit just when you
1839 * are about to discover the bug.
1841 signal(SIGALRM, grace_alarm_handler);
1843 alarm(options.login_grace_time);
1845 sshd_exchange_identification(sock_in, sock_out);
1846 #if defined(AFS_KRB5)
1847 /* If machine has AFS, set process authentication group. */
1852 #endif /* AFS || AFS_KRB5 */
1854 packet_set_nonblocking();
1856 /* allocate authentication context */
1857 authctxt = xcalloc(1, sizeof(*authctxt));
1859 authctxt->loginmsg = &loginmsg;
1861 /* XXX global for cleanup, access from other modules */
1862 the_authctxt = authctxt;
1864 /* prepare buffer to collect messages to display to user after login */
1865 buffer_init(&loginmsg);
1868 if (privsep_preauth(authctxt) == 1)
1871 /* perform the key exchange */
1872 /* authenticate user and start session */
1875 do_authentication2(authctxt);
1878 do_authentication(authctxt);
1881 * If we use privilege separation, the unprivileged child transfers
1882 * the current keystate and exits
1885 mm_send_keystate(pmonitor);
1891 * Cancel the alarm we set to limit the time taken for
1895 signal(SIGALRM, SIG_DFL);
1896 authctxt->authenticated = 1;
1897 if (startup_pipe != -1) {
1898 close(startup_pipe);
1902 #ifdef SSH_AUDIT_EVENTS
1903 audit_event(SSH_AUTH_SUCCESS);
1907 * In privilege separation, we fork another child and prepare
1908 * file descriptor passing.
1911 privsep_postauth(authctxt);
1912 /* the monitor process [priv] will not return */
1914 destroy_sensitive_data();
1917 /* Start session. */
1918 do_authenticated(authctxt);
1920 /* The connection has been terminated. */
1921 verbose("Closing connection to %.100s", remote_ip);
1924 if (options.use_pam)
1926 #endif /* USE_PAM */
1928 #ifdef SSH_AUDIT_EVENTS
1929 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1941 * Decrypt session_key_int using our private server key and private host key
1942 * (key with larger modulus first).
1945 ssh1_session_key(BIGNUM *session_key_int)
1949 if (BN_cmp(sensitive_data.server_key->rsa->n,
1950 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1951 /* Server key has bigger modulus. */
1952 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1953 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1954 SSH_KEY_BITS_RESERVED) {
1955 fatal("do_connection: %s: "
1956 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1957 get_remote_ipaddr(),
1958 BN_num_bits(sensitive_data.server_key->rsa->n),
1959 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1960 SSH_KEY_BITS_RESERVED);
1962 if (rsa_private_decrypt(session_key_int, session_key_int,
1963 sensitive_data.server_key->rsa) <= 0)
1965 if (rsa_private_decrypt(session_key_int, session_key_int,
1966 sensitive_data.ssh1_host_key->rsa) <= 0)
1969 /* Host key has bigger modulus (or they are equal). */
1970 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1971 BN_num_bits(sensitive_data.server_key->rsa->n) +
1972 SSH_KEY_BITS_RESERVED) {
1973 fatal("do_connection: %s: "
1974 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1975 get_remote_ipaddr(),
1976 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1977 BN_num_bits(sensitive_data.server_key->rsa->n),
1978 SSH_KEY_BITS_RESERVED);
1980 if (rsa_private_decrypt(session_key_int, session_key_int,
1981 sensitive_data.ssh1_host_key->rsa) < 0)
1983 if (rsa_private_decrypt(session_key_int, session_key_int,
1984 sensitive_data.server_key->rsa) < 0)
1997 BIGNUM *session_key_int;
1998 u_char session_key[SSH_SESSION_KEY_LENGTH];
2000 u_int cipher_type, auth_mask, protocol_flags;
2004 * Generate check bytes that the client must send back in the user
2005 * packet in order for it to be accepted; this is used to defy ip
2006 * spoofing attacks. Note that this only works against somebody
2007 * doing IP spoofing from a remote machine; any machine on the local
2008 * network can still see outgoing packets and catch the random
2009 * cookie. This only affects rhosts authentication, and this is one
2010 * of the reasons why it is inherently insecure.
2012 for (i = 0; i < 8; i++) {
2015 cookie[i] = rnd & 0xff;
2020 * Send our public key. We include in the packet 64 bits of random
2021 * data that must be matched in the reply in order to prevent IP
2024 packet_start(SSH_SMSG_PUBLIC_KEY);
2025 for (i = 0; i < 8; i++)
2026 packet_put_char(cookie[i]);
2028 /* Store our public server RSA key. */
2029 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2030 packet_put_bignum(sensitive_data.server_key->rsa->e);
2031 packet_put_bignum(sensitive_data.server_key->rsa->n);
2033 /* Store our public host RSA key. */
2034 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2035 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2036 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2038 /* Put protocol flags. */
2039 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2041 /* Declare which ciphers we support. */
2042 packet_put_int(cipher_mask_ssh1(0));
2044 /* Declare supported authentication types. */
2046 if (options.rhosts_rsa_authentication)
2047 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2048 if (options.rsa_authentication)
2049 auth_mask |= 1 << SSH_AUTH_RSA;
2050 if (options.challenge_response_authentication == 1)
2051 auth_mask |= 1 << SSH_AUTH_TIS;
2052 if (options.password_authentication)
2053 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2054 packet_put_int(auth_mask);
2056 /* Send the packet and wait for it to be sent. */
2058 packet_write_wait();
2060 debug("Sent %d bit server key and %d bit host key.",
2061 BN_num_bits(sensitive_data.server_key->rsa->n),
2062 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2064 /* Read clients reply (cipher type and session key). */
2065 packet_read_expect(SSH_CMSG_SESSION_KEY);
2067 /* Get cipher type and check whether we accept this. */
2068 cipher_type = packet_get_char();
2070 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2071 packet_disconnect("Warning: client selects unsupported cipher.");
2073 /* Get check bytes from the packet. These must match those we
2074 sent earlier with the public key packet. */
2075 for (i = 0; i < 8; i++)
2076 if (cookie[i] != packet_get_char())
2077 packet_disconnect("IP Spoofing check bytes do not match.");
2079 debug("Encryption type: %.200s", cipher_name(cipher_type));
2081 /* Get the encrypted integer. */
2082 if ((session_key_int = BN_new()) == NULL)
2083 fatal("do_ssh1_kex: BN_new failed");
2084 packet_get_bignum(session_key_int);
2086 protocol_flags = packet_get_int();
2087 packet_set_protocol_flags(protocol_flags);
2090 /* Decrypt session_key_int using host/server keys */
2091 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2094 * Extract session key from the decrypted integer. The key is in the
2095 * least significant 256 bits of the integer; the first byte of the
2096 * key is in the highest bits.
2099 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2100 len = BN_num_bytes(session_key_int);
2101 if (len < 0 || (u_int)len > sizeof(session_key)) {
2102 error("do_ssh1_kex: bad session key len from %s: "
2103 "session_key_int %d > sizeof(session_key) %lu",
2104 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2107 memset(session_key, 0, sizeof(session_key));
2108 BN_bn2bin(session_key_int,
2109 session_key + sizeof(session_key) - len);
2111 derive_ssh1_session_id(
2112 sensitive_data.ssh1_host_key->rsa->n,
2113 sensitive_data.server_key->rsa->n,
2114 cookie, session_id);
2116 * Xor the first 16 bytes of the session key with the
2119 for (i = 0; i < 16; i++)
2120 session_key[i] ^= session_id[i];
2124 int bytes = BN_num_bytes(session_key_int);
2125 u_char *buf = xmalloc(bytes);
2128 logit("do_connection: generating a fake encryption key");
2129 BN_bn2bin(session_key_int, buf);
2131 MD5_Update(&md, buf, bytes);
2132 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2133 MD5_Final(session_key, &md);
2135 MD5_Update(&md, session_key, 16);
2136 MD5_Update(&md, buf, bytes);
2137 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2138 MD5_Final(session_key + 16, &md);
2139 memset(buf, 0, bytes);
2141 for (i = 0; i < 16; i++)
2142 session_id[i] = session_key[i] ^ session_key[i + 16];
2144 /* Destroy the private and public keys. No longer. */
2145 destroy_sensitive_data();
2148 mm_ssh1_session_id(session_id);
2150 /* Destroy the decrypted integer. It is no longer needed. */
2151 BN_clear_free(session_key_int);
2153 /* Set the session key. From this on all communications will be encrypted. */
2154 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2156 /* Destroy our copy of the session key. It is no longer needed. */
2157 memset(session_key, 0, sizeof(session_key));
2159 debug("Received session key; encryption turned on.");
2161 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2162 packet_start(SSH_SMSG_SUCCESS);
2164 packet_write_wait();
2168 * SSH2 key exchange: diffie-hellman-group1-sha1
2176 debug ("MYFLAG IS %d", myflag);
2177 if (options.ciphers != NULL) {
2178 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2179 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2180 } else if (options.none_enabled == 1) {
2181 debug ("WARNING: None cipher enabled");
2182 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2183 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE;
2185 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2186 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2187 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2188 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2190 if (options.macs != NULL) {
2191 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2192 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2194 if (options.compression == COMP_NONE) {
2195 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2196 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2197 } else if (options.compression == COMP_DELAYED) {
2198 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2199 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2202 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2208 char *newstr = NULL;
2209 orig = myproposal[PROPOSAL_KEX_ALGS];
2212 * If we don't have a host key, then there's no point advertising
2213 * the other key exchange algorithms
2216 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
2219 if (options.gss_keyex)
2220 gss = ssh_gssapi_server_mechanisms();
2225 xasprintf(&newstr, "%s,%s", gss, orig);
2232 * If we've got GSSAPI mechanisms, then we've got the 'null' host
2233 * key alg, but we can't tell people about it unless its the only
2234 * host key algorithm we support
2236 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
2237 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
2240 myproposal[PROPOSAL_KEX_ALGS] = newstr;
2242 fatal("No supported key exchange algorithms");
2246 /* start key exchange */
2247 /* start key exchange */
2248 kex = kex_setup(myproposal);
2249 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2250 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2251 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2252 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2254 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
2255 kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
2256 kex->kex[KEX_GSS_GEX_SHA1] = kexgss_server;
2259 kex->client_version_string=client_version_string;
2260 kex->server_version_string=server_version_string;
2261 kex->load_host_key=&get_hostkey_by_type;
2262 kex->host_key_index=&get_hostkey_index;
2266 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2268 session_id2 = kex->session_id;
2269 session_id2_len = kex->session_id_len;
2272 /* send 1st encrypted/maced/compressed message */
2273 packet_start(SSH2_MSG_IGNORE);
2274 packet_put_cstring("markus");
2276 packet_write_wait();
2281 /* server specific fatal cleanup */
2286 do_cleanup(the_authctxt);
2287 #ifdef SSH_AUDIT_EVENTS
2288 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2289 if (!use_privsep || mm_is_monitor())
2290 audit_event(SSH_CONNECTION_ABANDON);