1 /* $OpenBSD: sshd.c,v 1.364 2008/07/10 18:08:11 markus 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"
57 #include "openbsd-compat/sys-queue.h"
75 #include <openssl/dh.h>
76 #include <openssl/bn.h>
77 #include <openssl/md5.h>
78 #include <openssl/rand.h>
79 #include "openbsd-compat/openssl-compat.h"
81 #ifdef HAVE_SECUREWARE
82 #include <sys/security.h>
102 #include "myproposal.h"
103 #include "authfile.h"
104 #include "pathnames.h"
105 #include "atomicio.h"
106 #include "canohost.h"
107 #include "hostfile.h"
111 #include "dispatch.h"
112 #include "channels.h"
114 #include "monitor_mm.h"
119 #include "monitor_wrap.h"
120 #include "monitor_fdpass.h"
123 #ifdef USE_SECURITY_SESSION_API
124 #include <Security/AuthSession.h>
139 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
140 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
141 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
142 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
147 extern char *__progname;
149 /* Server configuration options. */
150 ServerOptions options;
152 /* Name of the server configuration file. */
153 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
156 * Debug mode flag. This can be set on the command line. If debug
157 * mode is enabled, extra debugging output will be sent to the system
158 * log, the daemon will not go to background, and will exit after processing
159 * the first connection.
163 /* Flag indicating that the daemon should only test the configuration and keys. */
166 /* Flag indicating that the daemon is being started from inetd. */
169 /* Flag indicating that sshd should not detach and become a daemon. */
170 int no_daemon_flag = 0;
172 /* debug goes to stderr unless inetd_flag is set */
175 /* Saved arguments to main(). */
180 int rexeced_flag = 0;
186 * The sockets that the server is listening; this is used in the SIGHUP
189 #define MAX_LISTEN_SOCKS 16
190 int listen_socks[MAX_LISTEN_SOCKS];
191 int num_listen_socks = 0;
194 * the client's version string, passed by sshd2 in compat mode. if != NULL,
195 * sshd will skip the version-number exchange
197 char *client_version_string = NULL;
198 char *server_version_string = NULL;
200 /* for rekeying XXX fixme */
204 * Any really sensitive data in the application is contained in this
205 * structure. The idea is that this structure could be locked into memory so
206 * that the pages do not get written into swap. However, there are some
207 * problems. The private key contains BIGNUMs, and we do not (in principle)
208 * have access to the internals of them, and locking just the structure is
209 * not very useful. Currently, memory locking is not implemented.
212 Key *server_key; /* ephemeral server key */
213 Key *ssh1_host_key; /* ssh1 host key */
214 Key **host_keys; /* all private host keys */
217 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
221 * Flag indicating whether the RSA server key needs to be regenerated.
222 * Is set in the SIGALRM handler and cleared when the key is regenerated.
224 static volatile sig_atomic_t key_do_regen = 0;
226 /* This is set to true when a signal is received. */
227 static volatile sig_atomic_t received_sighup = 0;
228 static volatile sig_atomic_t received_sigterm = 0;
230 /* session identifier, used by RSA-auth */
231 u_char session_id[16];
234 u_char *session_id2 = NULL;
235 u_int session_id2_len = 0;
237 /* record remote hostname or ip */
238 u_int utmp_len = MAXHOSTNAMELEN;
240 /* options.max_startup sized array of fd ints */
241 int *startup_pipes = NULL;
242 int startup_pipe; /* in child */
244 /* variables used for privilege separation */
245 int use_privsep = -1;
246 struct monitor *pmonitor = NULL;
248 /* global authentication context */
249 Authctxt *the_authctxt = NULL;
251 /* sshd_config buffer */
254 /* message to be displayed after login */
257 /* Unprivileged user */
258 struct passwd *privsep_pw = NULL;
260 /* Prototypes for various functions defined later in this file. */
261 void destroy_sensitive_data(void);
262 void demote_sensitive_data(void);
264 static void do_ssh1_kex(void);
265 static void do_ssh2_kex(void);
268 * Close all listening sockets
271 close_listen_socks(void)
275 for (i = 0; i < num_listen_socks; i++)
276 close(listen_socks[i]);
277 num_listen_socks = -1;
281 close_startup_pipes(void)
286 for (i = 0; i < options.max_startups; i++)
287 if (startup_pipes[i] != -1)
288 close(startup_pipes[i]);
292 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
293 * the effect is to reread the configuration file (and to regenerate
299 sighup_handler(int sig)
301 int save_errno = errno;
304 signal(SIGHUP, sighup_handler);
309 * Called from the main program after receiving SIGHUP.
310 * Restarts the server.
315 logit("Received SIGHUP; restarting.");
316 close_listen_socks();
317 close_startup_pipes();
318 alarm(0); /* alarm timer persists across exec */
319 execv(saved_argv[0], saved_argv);
320 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
326 * Generic signal handler for terminating signals in the master daemon.
330 sigterm_handler(int sig)
332 received_sigterm = sig;
336 * SIGCHLD handler. This is called whenever a child dies. This will then
337 * reap any zombies left by exited children.
341 main_sigchld_handler(int sig)
343 int save_errno = errno;
347 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
348 (pid < 0 && errno == EINTR))
351 signal(SIGCHLD, main_sigchld_handler);
356 * Signal handler for the alarm after the login grace period has expired.
360 grace_alarm_handler(int sig)
362 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
363 kill(pmonitor->m_pid, SIGALRM);
365 /* Log error and exit. */
366 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
370 * Signal handler for the key regeneration alarm. Note that this
371 * alarm only occurs in the daemon waiting for connections, and it does not
372 * do anything with the private key or random state before forking.
373 * Thus there should be no concurrency control/asynchronous execution
377 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 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
393 key_regeneration_alarm(int sig)
395 int save_errno = errno;
397 signal(SIGALRM, SIG_DFL);
403 sshd_exchange_identification(int sock_in, int sock_out)
407 int remote_major, remote_minor;
409 char *s, *newline = "\n";
410 char buf[256]; /* Must not be larger than remote_version. */
411 char remote_version[256]; /* Must be at least as big as buf. */
413 if ((options.protocol & SSH_PROTO_1) &&
414 (options.protocol & SSH_PROTO_2)) {
415 major = PROTOCOL_MAJOR_1;
417 } else if (options.protocol & SSH_PROTO_2) {
418 major = PROTOCOL_MAJOR_2;
419 minor = PROTOCOL_MINOR_2;
422 major = PROTOCOL_MAJOR_1;
423 minor = PROTOCOL_MINOR_1;
425 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
426 SSH_RELEASE, newline);
427 server_version_string = xstrdup(buf);
429 /* Send our protocol version identification. */
430 if (atomicio(vwrite, sock_out, server_version_string,
431 strlen(server_version_string))
432 != strlen(server_version_string)) {
433 logit("Could not write ident string to %s", get_remote_ipaddr());
437 /* Read other sides version identification. */
438 memset(buf, 0, sizeof(buf));
439 for (i = 0; i < sizeof(buf) - 1; i++) {
440 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
441 logit("Did not receive identification string from %s",
442 get_remote_ipaddr());
445 if (buf[i] == '\r') {
447 /* Kludge for F-Secure Macintosh < 1.0.2 */
449 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
453 if (buf[i] == '\n') {
458 buf[sizeof(buf) - 1] = 0;
459 client_version_string = xstrdup(buf);
462 * Check that the versions match. In future this might accept
463 * several versions and set appropriate flags to handle them.
465 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
466 &remote_major, &remote_minor, remote_version) != 3) {
467 s = "Protocol mismatch.\n";
468 (void) atomicio(vwrite, sock_out, s, strlen(s));
471 logit("Bad protocol version identification '%.100s' from %s",
472 client_version_string, get_remote_ipaddr());
475 debug("Client protocol version %d.%d; client software version %.100s",
476 remote_major, remote_minor, remote_version);
477 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s",
478 get_remote_ipaddr(), get_remote_port(),
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)
594 /* Enable challenge-response authentication for privilege separation */
595 privsep_challenge_enable();
598 arc4random_buf(rnd, sizeof(rnd));
599 RAND_seed(rnd, sizeof(rnd));
601 /* Demote the private keys to public keys. */
602 demote_sensitive_data();
604 /* Change our root directory */
605 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
606 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
608 if (chdir("/") == -1)
609 fatal("chdir(\"/\"): %s", strerror(errno));
611 /* Drop our privileges */
612 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
613 (u_int)privsep_pw->pw_gid);
615 /* XXX not ready, too heavy after chroot */
616 do_setusercontext(privsep_pw);
618 gidset[0] = privsep_pw->pw_gid;
619 if (setgroups(1, gidset) < 0)
620 fatal("setgroups: %.100s", strerror(errno));
621 permanently_set_uid(privsep_pw);
626 privsep_preauth(Authctxt *authctxt)
631 /* Set up unprivileged child process to deal with network data */
632 pmonitor = monitor_init();
633 /* Store a pointer to the kex for later rekeying */
634 pmonitor->m_pkex = &xxx_kex;
638 fatal("fork of unprivileged child failed");
639 } else if (pid != 0) {
640 debug2("Network child is on pid %ld", (long)pid);
642 close(pmonitor->m_recvfd);
643 pmonitor->m_pid = pid;
644 monitor_child_preauth(authctxt, pmonitor);
645 close(pmonitor->m_sendfd);
648 monitor_sync(pmonitor);
650 /* Wait for the child's exit status */
651 while (waitpid(pid, &status, 0) < 0)
658 close(pmonitor->m_sendfd);
660 /* Demote the child */
661 if (getuid() == 0 || geteuid() == 0)
662 privsep_preauth_child();
663 setproctitle("%s", "[net]");
669 privsep_postauth(Authctxt *authctxt)
673 #ifdef DISABLE_FD_PASSING
676 if (authctxt->pw->pw_uid == 0 || options.use_login) {
678 /* File descriptor passing is broken or root login */
683 /* New socket pair */
684 monitor_reinit(pmonitor);
686 pmonitor->m_pid = fork();
687 if (pmonitor->m_pid == -1)
688 fatal("fork of unprivileged child failed");
689 else if (pmonitor->m_pid != 0) {
690 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
691 close(pmonitor->m_recvfd);
692 buffer_clear(&loginmsg);
693 monitor_child_postauth(pmonitor);
699 close(pmonitor->m_sendfd);
701 /* Demote the private keys to public keys. */
702 demote_sensitive_data();
705 arc4random_buf(rnd, sizeof(rnd));
706 RAND_seed(rnd, sizeof(rnd));
708 /* Drop privileges */
709 do_setusercontext(authctxt->pw);
712 /* It is safe now to apply the key state */
713 monitor_apply_keystate(pmonitor);
716 * Tell the packet layer that authentication was successful, since
717 * this information is not part of the key state.
719 packet_set_authenticated();
723 list_hostkey_types(void)
731 for (i = 0; i < options.num_host_key_files; i++) {
732 Key *key = sensitive_data.host_keys[i];
738 if (buffer_len(&b) > 0)
739 buffer_append(&b, ",", 1);
740 p = key_ssh_name(key);
741 buffer_append(&b, p, strlen(p));
745 buffer_append(&b, "\0", 1);
746 ret = xstrdup(buffer_ptr(&b));
748 debug("list_hostkey_types: %s", ret);
753 get_hostkey_by_type(int type)
757 for (i = 0; i < options.num_host_key_files; i++) {
758 Key *key = sensitive_data.host_keys[i];
759 if (key != NULL && key->type == type)
766 get_hostkey_by_index(int ind)
768 if (ind < 0 || ind >= options.num_host_key_files)
770 return (sensitive_data.host_keys[ind]);
774 get_hostkey_index(Key *key)
778 for (i = 0; i < options.num_host_key_files; i++) {
779 if (key == sensitive_data.host_keys[i])
786 * returns 1 if connection should be dropped, 0 otherwise.
787 * dropping starts at connection #max_startups_begin with a probability
788 * of (max_startups_rate/100). the probability increases linearly until
789 * all connections are dropped for startups > max_startups
792 drop_connection(int startups)
796 if (startups < options.max_startups_begin)
798 if (startups >= options.max_startups)
800 if (options.max_startups_rate == 100)
803 p = 100 - options.max_startups_rate;
804 p *= startups - options.max_startups_begin;
805 p /= options.max_startups - options.max_startups_begin;
806 p += options.max_startups_rate;
807 r = arc4random_uniform(100);
809 debug("drop_connection: p %d, r %d", p, r);
810 return (r < p) ? 1 : 0;
816 fprintf(stderr, "%s, %s\n",
817 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
819 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n"
820 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n"
821 " [-o option] [-p port] [-u len]\n"
827 send_rexec_state(int fd, Buffer *conf)
831 debug3("%s: entering fd = %d config len %d", __func__, fd,
835 * Protocol from reexec master to child:
836 * string configuration
837 * u_int ephemeral_key_follows
838 * bignum e (only if ephemeral_key_follows == 1)
844 * string rngseed (only if OpenSSL is not self-seeded)
847 buffer_put_cstring(&m, buffer_ptr(conf));
849 if (sensitive_data.server_key != NULL &&
850 sensitive_data.server_key->type == KEY_RSA1) {
851 buffer_put_int(&m, 1);
852 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
853 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
854 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
855 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
856 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
857 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
859 buffer_put_int(&m, 0);
861 #ifndef OPENSSL_PRNG_ONLY
862 rexec_send_rng_seed(&m);
865 if (ssh_msg_send(fd, 0, &m) == -1)
866 fatal("%s: ssh_msg_send failed", __func__);
870 debug3("%s: done", __func__);
874 recv_rexec_state(int fd, Buffer *conf)
880 debug3("%s: entering fd = %d", __func__, fd);
884 if (ssh_msg_recv(fd, &m) == -1)
885 fatal("%s: ssh_msg_recv failed", __func__);
886 if (buffer_get_char(&m) != 0)
887 fatal("%s: rexec version mismatch", __func__);
889 cp = buffer_get_string(&m, &len);
891 buffer_append(conf, cp, len + 1);
894 if (buffer_get_int(&m)) {
895 if (sensitive_data.server_key != NULL)
896 key_free(sensitive_data.server_key);
897 sensitive_data.server_key = key_new_private(KEY_RSA1);
898 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
899 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
900 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
901 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
902 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
903 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
904 rsa_generate_additional_parameters(
905 sensitive_data.server_key->rsa);
908 #ifndef OPENSSL_PRNG_ONLY
909 rexec_recv_rng_seed(&m);
914 debug3("%s: done", __func__);
917 /* Accept a connection from inetd */
919 server_accept_inetd(int *sock_in, int *sock_out)
925 close(REEXEC_CONFIG_PASS_FD);
926 *sock_in = *sock_out = dup(STDIN_FILENO);
928 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
929 close(REEXEC_STARTUP_PIPE_FD);
932 *sock_in = dup(STDIN_FILENO);
933 *sock_out = dup(STDOUT_FILENO);
936 * We intentionally do not close the descriptors 0, 1, and 2
937 * as our code for setting the descriptors won't work if
938 * ttyfd happens to be one of those.
940 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
941 dup2(fd, STDIN_FILENO);
942 dup2(fd, STDOUT_FILENO);
943 if (fd > STDOUT_FILENO)
946 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
950 * Listen for TCP connections
955 int ret, listen_sock, on = 1;
957 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
959 int socksizelen = sizeof(int);
961 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
962 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
964 if (num_listen_socks >= MAX_LISTEN_SOCKS)
965 fatal("Too many listen sockets. "
966 "Enlarge MAX_LISTEN_SOCKS");
967 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
968 ntop, sizeof(ntop), strport, sizeof(strport),
969 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
970 error("getnameinfo failed: %.100s",
971 ssh_gai_strerror(ret));
974 /* Create socket for listening. */
975 listen_sock = socket(ai->ai_family, ai->ai_socktype,
977 if (listen_sock < 0) {
978 /* kernel may not support ipv6 */
979 verbose("socket: %.100s", strerror(errno));
982 if (set_nonblock(listen_sock) == -1) {
987 * Set socket options.
988 * Allow local port reuse in TIME_WAIT.
990 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
991 &on, sizeof(on)) == -1)
992 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
995 /* Only communicate in IPv6 over AF_INET6 sockets. */
996 if (ai->ai_family == AF_INET6) {
997 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY,
998 &on, sizeof(on)) == -1)
999 error("setsockopt IPV6_V6ONLY: %s",
1004 debug("Bind to port %s on %s.", strport, ntop);
1006 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF,
1007 &socksize, &socksizelen);
1008 debug("Server TCP RWIN socket size: %d", socksize);
1009 debug("HPN Buffer Size: %d", options.hpn_buffer_size);
1011 /* Bind the socket to the desired port. */
1012 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1013 error("Bind to port %s on %s failed: %.200s.",
1014 strport, ntop, strerror(errno));
1018 listen_socks[num_listen_socks] = listen_sock;
1021 /* Start listening on the port. */
1022 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1023 fatal("listen on [%s]:%s: %.100s",
1024 ntop, strport, strerror(errno));
1025 logit("Server listening on %s port %s.", ntop, strport);
1027 freeaddrinfo(options.listen_addrs);
1029 if (!num_listen_socks)
1030 fatal("Cannot bind any address.");
1034 * The main TCP accept loop. Note that, for the non-debug case, returns
1035 * from this function are in a forked subprocess.
1038 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1041 int i, j, ret, maxfd;
1042 int key_used = 0, startups = 0;
1043 int startup_p[2] = { -1 , -1 };
1044 struct sockaddr_storage from;
1048 /* setup fd set for accept */
1051 for (i = 0; i < num_listen_socks; i++)
1052 if (listen_socks[i] > maxfd)
1053 maxfd = listen_socks[i];
1054 /* pipes connected to unauthenticated childs */
1055 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1056 for (i = 0; i < options.max_startups; i++)
1057 startup_pipes[i] = -1;
1060 * Stay listening for connections until the system crashes or
1061 * the daemon is killed with a signal.
1064 if (received_sighup)
1068 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1071 for (i = 0; i < num_listen_socks; i++)
1072 FD_SET(listen_socks[i], fdset);
1073 for (i = 0; i < options.max_startups; i++)
1074 if (startup_pipes[i] != -1)
1075 FD_SET(startup_pipes[i], fdset);
1077 /* Wait in select until there is a connection. */
1078 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1079 if (ret < 0 && errno != EINTR)
1080 error("select: %.100s", strerror(errno));
1081 if (received_sigterm) {
1082 logit("Received signal %d; terminating.",
1083 (int) received_sigterm);
1084 close_listen_socks();
1085 unlink(options.pid_file);
1088 if (key_used && key_do_regen) {
1089 generate_ephemeral_server_key();
1096 for (i = 0; i < options.max_startups; i++)
1097 if (startup_pipes[i] != -1 &&
1098 FD_ISSET(startup_pipes[i], fdset)) {
1100 * the read end of the pipe is ready
1101 * if the child has closed the pipe
1102 * after successful authentication
1103 * or if the child has died
1105 close(startup_pipes[i]);
1106 startup_pipes[i] = -1;
1109 for (i = 0; i < num_listen_socks; i++) {
1110 if (!FD_ISSET(listen_socks[i], fdset))
1112 fromlen = sizeof(from);
1113 *newsock = accept(listen_socks[i],
1114 (struct sockaddr *)&from, &fromlen);
1116 if (errno != EINTR && errno != EAGAIN &&
1117 errno != EWOULDBLOCK)
1118 error("accept: %.100s", strerror(errno));
1121 if (unset_nonblock(*newsock) == -1) {
1125 if (drop_connection(startups) == 1) {
1126 debug("drop connection #%d", startups);
1130 if (pipe(startup_p) == -1) {
1135 if (rexec_flag && socketpair(AF_UNIX,
1136 SOCK_STREAM, 0, config_s) == -1) {
1137 error("reexec socketpair: %s",
1140 close(startup_p[0]);
1141 close(startup_p[1]);
1145 for (j = 0; j < options.max_startups; j++)
1146 if (startup_pipes[j] == -1) {
1147 startup_pipes[j] = startup_p[0];
1148 if (maxfd < startup_p[0])
1149 maxfd = startup_p[0];
1155 * Got connection. Fork a child to handle it, unless
1156 * we are in debugging mode.
1160 * In debugging mode. Close the listening
1161 * socket, and start processing the
1162 * connection without forking.
1164 debug("Server will not fork when running in debugging mode.");
1165 close_listen_socks();
1166 *sock_in = *newsock;
1167 *sock_out = *newsock;
1168 close(startup_p[0]);
1169 close(startup_p[1]);
1173 send_rexec_state(config_s[0],
1181 * Normal production daemon. Fork, and have
1182 * the child process the connection. The
1183 * parent continues listening.
1185 platform_pre_fork();
1186 if ((pid = fork()) == 0) {
1188 * Child. Close the listening and
1189 * max_startup sockets. Start using
1190 * the accepted socket. Reinitialize
1191 * logging (since our pid has changed).
1192 * We break out of the loop to handle
1195 platform_post_fork_child();
1196 startup_pipe = startup_p[1];
1197 close_startup_pipes();
1198 close_listen_socks();
1199 *sock_in = *newsock;
1200 *sock_out = *newsock;
1201 log_init(__progname,
1203 options.log_facility,
1210 /* Parent. Stay in the loop. */
1211 platform_post_fork_parent(pid);
1213 error("fork: %.100s", strerror(errno));
1215 debug("Forked child %ld.", (long)pid);
1217 close(startup_p[1]);
1220 send_rexec_state(config_s[0], &cfg);
1226 * Mark that the key has been used (it
1227 * was "given" to the child).
1229 if ((options.protocol & SSH_PROTO_1) &&
1231 /* Schedule server key regeneration alarm. */
1232 signal(SIGALRM, key_regeneration_alarm);
1233 alarm(options.key_regeneration_time);
1240 * Ensure that our random state differs
1241 * from that of the child
1246 /* child process check (or debug mode) */
1247 if (num_listen_socks < 0)
1254 * Main program for the daemon.
1257 main(int ac, char **av)
1259 extern char *optarg;
1262 int sock_in = -1, sock_out = -1, newsock = -1;
1263 const char *remote_ip;
1264 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1266 char *line, *p, *cp;
1267 int config_s[2] = { -1 , -1 };
1268 u_int64_t ibytes, obytes;
1273 #ifdef HAVE_SECUREWARE
1274 (void)set_auth_parameters(ac, av);
1276 __progname = ssh_get_progname(av[0]);
1279 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1282 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1283 for (i = 0; i < ac; i++)
1284 saved_argv[i] = xstrdup(av[i]);
1285 saved_argv[i] = NULL;
1287 #ifndef HAVE_SETPROCTITLE
1288 /* Prepare for later setproctitle emulation */
1289 compat_init_setproctitle(ac, av);
1293 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1294 debug("setgroups(): %.200s", strerror(errno));
1296 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1299 /* Initialize configuration options to their default values. */
1300 initialize_server_options(&options);
1302 /* Parse command-line arguments. */
1303 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1306 options.address_family = AF_INET;
1309 options.address_family = AF_INET6;
1312 config_file_name = optarg;
1315 if (debug_flag == 0) {
1317 options.log_level = SYSLOG_LEVEL_DEBUG1;
1318 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1319 options.log_level++;
1341 options.log_level = SYSLOG_LEVEL_QUIET;
1344 options.server_key_bits = (int)strtonum(optarg, 256,
1348 options.ports_from_cmdline = 1;
1349 if (options.num_ports >= MAX_PORTS) {
1350 fprintf(stderr, "too many ports.\n");
1353 options.ports[options.num_ports++] = a2port(optarg);
1354 if (options.ports[options.num_ports-1] == 0) {
1355 fprintf(stderr, "Bad port number.\n");
1360 if ((options.login_grace_time = convtime(optarg)) == -1) {
1361 fprintf(stderr, "Invalid login grace time.\n");
1366 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1367 fprintf(stderr, "Invalid key regeneration interval.\n");
1372 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1373 fprintf(stderr, "too many host keys.\n");
1376 options.host_key_files[options.num_host_key_files++] = optarg;
1386 while ((p = strsep(&cp, ",")) && *p != '\0') {
1387 if (strncmp(p, "addr=", 5) == 0)
1388 test_addr = xstrdup(p + 5);
1389 else if (strncmp(p, "host=", 5) == 0)
1390 test_host = xstrdup(p + 5);
1391 else if (strncmp(p, "user=", 5) == 0)
1392 test_user = xstrdup(p + 5);
1394 fprintf(stderr, "Invalid test "
1395 "mode specification %s\n", p);
1401 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1402 if (utmp_len > MAXHOSTNAMELEN) {
1403 fprintf(stderr, "Invalid utmp length.\n");
1408 line = xstrdup(optarg);
1409 if (process_server_config_line(&options, line,
1410 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1420 if (rexeced_flag || inetd_flag)
1422 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1423 fatal("sshd re-exec requires execution with an absolute path");
1425 closefrom(REEXEC_MIN_FREE_FD);
1427 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1429 SSLeay_add_all_algorithms();
1432 * Force logging to stderr until we have loaded the private host
1433 * key (unless started from inetd)
1435 log_init(__progname,
1436 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1437 SYSLOG_LEVEL_INFO : options.log_level,
1438 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1439 SYSLOG_FACILITY_AUTH : options.log_facility,
1440 log_stderr || !inetd_flag);
1443 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1444 * root's environment
1446 if (getenv("KRB5CCNAME") != NULL)
1447 unsetenv("KRB5CCNAME");
1450 /* Cray can define user privs drop all privs now!
1451 * Not needed on PRIV_SU systems!
1456 sensitive_data.server_key = NULL;
1457 sensitive_data.ssh1_host_key = NULL;
1458 sensitive_data.have_ssh1_key = 0;
1459 sensitive_data.have_ssh2_key = 0;
1462 * If we're doing an extended config test, make sure we have all of
1463 * the parameters we need. If we're not doing an extended test,
1464 * do not silently ignore connection test params.
1466 if (test_flag >= 2 &&
1467 (test_user != NULL || test_host != NULL || test_addr != NULL)
1468 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1469 fatal("user, host and addr are all required when testing "
1471 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1473 fatal("Config test connection parameter (-C) provided without "
1476 /* Fetch our configuration */
1479 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1481 load_server_config(config_file_name, &cfg);
1483 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1484 &cfg, NULL, NULL, NULL);
1488 /* Fill in default values for those options not explicitly set. */
1489 fill_default_server_options(&options);
1491 /* challenge-response is implemented via keyboard interactive */
1492 if (options.challenge_response_authentication)
1493 options.kbd_interactive_authentication = 1;
1495 /* set default channel AF */
1496 channel_set_af(options.address_family);
1498 /* Check that there are no remaining arguments. */
1500 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1504 debug("sshd version %.100s", SSH_RELEASE);
1506 /* Store privilege separation user for later use if required. */
1507 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1508 if (use_privsep || options.kerberos_authentication)
1509 fatal("Privilege separation user %s does not exist",
1512 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1513 privsep_pw = pwcopy(privsep_pw);
1514 xfree(privsep_pw->pw_passwd);
1515 privsep_pw->pw_passwd = xstrdup("*");
1519 /* load private host keys */
1520 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1522 for (i = 0; i < options.num_host_key_files; i++)
1523 sensitive_data.host_keys[i] = NULL;
1525 for (i = 0; i < options.num_host_key_files; i++) {
1526 key = key_load_private(options.host_key_files[i], "", NULL);
1527 sensitive_data.host_keys[i] = key;
1529 error("Could not load host key: %s",
1530 options.host_key_files[i]);
1531 sensitive_data.host_keys[i] = NULL;
1534 switch (key->type) {
1536 sensitive_data.ssh1_host_key = key;
1537 sensitive_data.have_ssh1_key = 1;
1541 sensitive_data.have_ssh2_key = 1;
1544 debug("private host key: #%d type %d %s", i, key->type,
1547 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1548 logit("Disabling protocol version 1. Could not load host key");
1549 options.protocol &= ~SSH_PROTO_1;
1552 /* The GSSAPI key exchange can run without a host key */
1553 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1554 logit("Disabling protocol version 2. Could not load host key");
1555 options.protocol &= ~SSH_PROTO_2;
1558 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1559 logit("sshd: no hostkeys available -- exiting.");
1563 /* Check certain values for sanity. */
1564 if (options.protocol & SSH_PROTO_1) {
1565 if (options.server_key_bits < 512 ||
1566 options.server_key_bits > 32768) {
1567 fprintf(stderr, "Bad server key size.\n");
1571 * Check that server and host key lengths differ sufficiently. This
1572 * is necessary to make double encryption work with rsaref. Oh, I
1573 * hate software patents. I dont know if this can go? Niels
1575 if (options.server_key_bits >
1576 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1577 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1578 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1579 SSH_KEY_BITS_RESERVED) {
1580 options.server_key_bits =
1581 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1582 SSH_KEY_BITS_RESERVED;
1583 debug("Forcing server key to %d bits to make it differ from host key.",
1584 options.server_key_bits);
1591 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1592 (S_ISDIR(st.st_mode) == 0))
1593 fatal("Missing privilege separation directory: %s",
1594 _PATH_PRIVSEP_CHROOT_DIR);
1597 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1598 (st.st_uid != getuid () ||
1599 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1601 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1603 fatal("%s must be owned by root and not group or "
1604 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1607 if (test_flag > 1) {
1608 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1609 parse_server_match_config(&options, test_user,
1610 test_host, test_addr);
1611 dump_config(&options);
1614 /* Configuration looks good, so exit if in test mode. */
1619 * Clear out any supplemental groups we may have inherited. This
1620 * prevents inadvertent creation of files with bad modes (in the
1621 * portable version at least, it's certainly possible for PAM
1622 * to create a file, and we can't control the code in every
1623 * module which might be used).
1625 if (setgroups(0, NULL) < 0)
1626 debug("setgroups() failed: %.200s", strerror(errno));
1629 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1630 for (i = 0; i < rexec_argc; i++) {
1631 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1632 rexec_argv[i] = saved_argv[i];
1634 rexec_argv[rexec_argc] = "-R";
1635 rexec_argv[rexec_argc + 1] = NULL;
1638 /* Ensure that umask disallows at least group and world write */
1639 new_umask = umask(0077) | 0022;
1640 (void) umask(new_umask);
1642 /* Initialize the log (it is reinitialized below in case we forked). */
1643 if (debug_flag && (!inetd_flag || rexeced_flag))
1645 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1648 * If not in debugging mode, and not started from inetd, disconnect
1649 * from the controlling terminal, and fork. The original process
1652 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1655 #endif /* TIOCNOTTY */
1656 if (daemon(0, 0) < 0)
1657 fatal("daemon() failed: %.200s", strerror(errno));
1659 /* Disconnect from the controlling tty. */
1661 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1663 (void) ioctl(fd, TIOCNOTTY, NULL);
1666 #endif /* TIOCNOTTY */
1668 /* Reinitialize the log (because of the fork above). */
1669 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1671 /* Initialize the random number generator. */
1674 /* Chdir to the root directory so that the current disk can be
1675 unmounted if desired. */
1678 /* ignore SIGPIPE */
1679 signal(SIGPIPE, SIG_IGN);
1681 /* Get a connection, either from inetd or a listening TCP socket */
1683 server_accept_inetd(&sock_in, &sock_out);
1687 if (options.protocol & SSH_PROTO_1)
1688 generate_ephemeral_server_key();
1690 signal(SIGHUP, sighup_handler);
1691 signal(SIGCHLD, main_sigchld_handler);
1692 signal(SIGTERM, sigterm_handler);
1693 signal(SIGQUIT, sigterm_handler);
1696 * Write out the pid file after the sigterm handler
1697 * is setup and the listen sockets are bound
1700 FILE *f = fopen(options.pid_file, "w");
1703 error("Couldn't create pid file \"%s\": %s",
1704 options.pid_file, strerror(errno));
1706 fprintf(f, "%ld\n", (long) getpid());
1711 /* Accept a connection and return in a forked child */
1712 server_accept_loop(&sock_in, &sock_out,
1713 &newsock, config_s);
1716 /* This is the child processing a new connection. */
1717 setproctitle("%s", "[accepted]");
1720 * Create a new session and process group since the 4.4BSD
1721 * setlogin() affects the entire process group. We don't
1722 * want the child to be able to affect the parent.
1724 #if !defined(SSHD_ACQUIRES_CTTY)
1726 * If setsid is called, on some platforms sshd will later acquire a
1727 * controlling terminal which will result in "could not set
1728 * controlling tty" errors.
1730 if (!debug_flag && !inetd_flag && setsid() < 0)
1731 error("setsid: %.100s", strerror(errno));
1737 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1738 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1739 dup2(newsock, STDIN_FILENO);
1740 dup2(STDIN_FILENO, STDOUT_FILENO);
1741 if (startup_pipe == -1)
1742 close(REEXEC_STARTUP_PIPE_FD);
1744 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1746 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1748 if (startup_pipe != -1)
1749 close(startup_pipe);
1751 execv(rexec_argv[0], rexec_argv);
1753 /* Reexec has failed, fall back and continue */
1754 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1755 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1756 log_init(__progname, options.log_level,
1757 options.log_facility, log_stderr);
1760 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1762 close(REEXEC_CONFIG_PASS_FD);
1763 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1764 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1765 dup2(fd, STDIN_FILENO);
1766 dup2(fd, STDOUT_FILENO);
1767 if (fd > STDERR_FILENO)
1770 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1771 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1775 * Disable the key regeneration alarm. We will not regenerate the
1776 * key since we are no longer in a position to give it to anyone. We
1777 * will not restart on SIGHUP since it no longer makes sense.
1780 signal(SIGALRM, SIG_DFL);
1781 signal(SIGHUP, SIG_DFL);
1782 signal(SIGTERM, SIG_DFL);
1783 signal(SIGQUIT, SIG_DFL);
1784 signal(SIGCHLD, SIG_DFL);
1785 signal(SIGINT, SIG_DFL);
1788 * Register our connection. This turns encryption off because we do
1791 packet_set_connection(sock_in, sock_out);
1792 packet_set_server();
1794 /* Set SO_KEEPALIVE if requested. */
1795 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1796 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1797 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1799 if ((remote_port = get_remote_port()) < 0) {
1800 debug("get_remote_port failed");
1805 * We use get_canonical_hostname with usedns = 0 instead of
1806 * get_remote_ipaddr here so IP options will be checked.
1808 (void) get_canonical_hostname(0);
1810 * The rest of the code depends on the fact that
1811 * get_remote_ipaddr() caches the remote ip, even if
1812 * the socket goes away.
1814 remote_ip = get_remote_ipaddr();
1816 #ifdef SSH_AUDIT_EVENTS
1817 audit_connection_from(remote_ip, remote_port);
1820 allow_severity = options.log_facility|LOG_INFO;
1821 deny_severity = options.log_facility|LOG_WARNING;
1822 /* Check whether logins are denied from this host. */
1823 if (packet_connection_is_on_socket()) {
1824 struct request_info req;
1826 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1829 if (!hosts_access(&req)) {
1830 debug("Connection refused by tcp wrapper");
1833 fatal("libwrap refuse returns");
1836 #endif /* LIBWRAP */
1838 /* Log the connection. */
1839 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1841 #ifdef USE_SECURITY_SESSION_API
1843 * Create a new security session for use by the new user login if
1844 * the current session is the root session or we are not launched
1845 * by inetd (eg: debugging mode or server mode). We do not
1846 * necessarily need to create a session if we are launched from
1847 * inetd because Panther xinetd will create a session for us.
1849 * The only case where this logic will fail is if there is an
1850 * inetd running in a non-root session which is not creating
1851 * new sessions for us. Then all the users will end up in the
1852 * same session (bad).
1854 * When the client exits, the session will be destroyed for us
1857 * We must create the session before any credentials are stored
1858 * (including AFS pags, which happens a few lines below).
1862 SecuritySessionId sid = 0;
1863 SessionAttributeBits sattrs = 0;
1865 err = SessionGetInfo(callerSecuritySession, &sid, &sattrs);
1867 error("SessionGetInfo() failed with error %.8X",
1870 debug("Current Session ID is %.8X / Session Attributes are %.8X",
1871 (unsigned) sid, (unsigned) sattrs);
1873 if (inetd_flag && !(sattrs & sessionIsRoot))
1874 debug("Running in inetd mode in a non-root session... "
1875 "assuming inetd created the session for us.");
1877 debug("Creating new security session...");
1878 err = SessionCreate(0, sessionHasTTY | sessionIsRemote);
1880 error("SessionCreate() failed with error %.8X",
1883 err = SessionGetInfo(callerSecuritySession, &sid,
1886 error("SessionGetInfo() failed with error %.8X",
1889 debug("New Session ID is %.8X / Session Attributes are %.8X",
1890 (unsigned) sid, (unsigned) sattrs);
1896 * We don't want to listen forever unless the other side
1897 * successfully authenticates itself. So we set up an alarm which is
1898 * cleared after successful authentication. A limit of zero
1899 * indicates no limit. Note that we don't set the alarm in debugging
1900 * mode; it is just annoying to have the server exit just when you
1901 * are about to discover the bug.
1903 signal(SIGALRM, grace_alarm_handler);
1905 alarm(options.login_grace_time);
1907 sshd_exchange_identification(sock_in, sock_out);
1908 #if defined(AFS_KRB5)
1909 /* If machine has AFS, set process authentication group. */
1914 #endif /* AFS || AFS_KRB5 */
1916 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1917 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1918 generate_ephemeral_server_key();
1920 packet_set_nonblocking();
1922 /* allocate authentication context */
1923 authctxt = xcalloc(1, sizeof(*authctxt));
1925 authctxt->loginmsg = &loginmsg;
1927 /* XXX global for cleanup, access from other modules */
1928 the_authctxt = authctxt;
1930 /* prepare buffer to collect messages to display to user after login */
1931 buffer_init(&loginmsg);
1934 if (privsep_preauth(authctxt) == 1)
1937 /* perform the key exchange */
1938 /* authenticate user and start session */
1941 do_authentication2(authctxt);
1944 do_authentication(authctxt);
1947 * If we use privilege separation, the unprivileged child transfers
1948 * the current keystate and exits
1951 mm_send_keystate(pmonitor);
1957 * Cancel the alarm we set to limit the time taken for
1961 signal(SIGALRM, SIG_DFL);
1962 authctxt->authenticated = 1;
1963 if (startup_pipe != -1) {
1964 close(startup_pipe);
1968 #ifdef SSH_AUDIT_EVENTS
1969 audit_event(SSH_AUTH_SUCCESS);
1973 if (options.gss_authentication && options.gss_deleg_creds) {
1974 temporarily_use_uid(authctxt->pw);
1975 ssh_gssapi_storecreds();
1980 if (options.use_pam) {
1987 * In privilege separation, we fork another child and prepare
1988 * file descriptor passing.
1991 privsep_postauth(authctxt);
1992 /* the monitor process [priv] will not return */
1994 destroy_sensitive_data();
1997 packet_set_timeout(options.client_alive_interval,
1998 options.client_alive_count_max);
2000 /* Start session. */
2001 do_authenticated(authctxt);
2003 /* The connection has been terminated. */
2004 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2005 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2006 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
2008 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2011 if (options.use_pam)
2013 #endif /* USE_PAM */
2015 #ifdef SSH_AUDIT_EVENTS
2016 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2028 * Decrypt session_key_int using our private server key and private host key
2029 * (key with larger modulus first).
2032 ssh1_session_key(BIGNUM *session_key_int)
2036 if (BN_cmp(sensitive_data.server_key->rsa->n,
2037 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2038 /* Server key has bigger modulus. */
2039 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2040 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2041 SSH_KEY_BITS_RESERVED) {
2042 fatal("do_connection: %s: "
2043 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2044 get_remote_ipaddr(),
2045 BN_num_bits(sensitive_data.server_key->rsa->n),
2046 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2047 SSH_KEY_BITS_RESERVED);
2049 if (rsa_private_decrypt(session_key_int, session_key_int,
2050 sensitive_data.server_key->rsa) <= 0)
2052 if (rsa_private_decrypt(session_key_int, session_key_int,
2053 sensitive_data.ssh1_host_key->rsa) <= 0)
2056 /* Host key has bigger modulus (or they are equal). */
2057 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2058 BN_num_bits(sensitive_data.server_key->rsa->n) +
2059 SSH_KEY_BITS_RESERVED) {
2060 fatal("do_connection: %s: "
2061 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2062 get_remote_ipaddr(),
2063 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2064 BN_num_bits(sensitive_data.server_key->rsa->n),
2065 SSH_KEY_BITS_RESERVED);
2067 if (rsa_private_decrypt(session_key_int, session_key_int,
2068 sensitive_data.ssh1_host_key->rsa) < 0)
2070 if (rsa_private_decrypt(session_key_int, session_key_int,
2071 sensitive_data.server_key->rsa) < 0)
2084 BIGNUM *session_key_int;
2085 u_char session_key[SSH_SESSION_KEY_LENGTH];
2087 u_int cipher_type, auth_mask, protocol_flags;
2090 * Generate check bytes that the client must send back in the user
2091 * packet in order for it to be accepted; this is used to defy ip
2092 * spoofing attacks. Note that this only works against somebody
2093 * doing IP spoofing from a remote machine; any machine on the local
2094 * network can still see outgoing packets and catch the random
2095 * cookie. This only affects rhosts authentication, and this is one
2096 * of the reasons why it is inherently insecure.
2098 arc4random_buf(cookie, sizeof(cookie));
2101 * Send our public key. We include in the packet 64 bits of random
2102 * data that must be matched in the reply in order to prevent IP
2105 packet_start(SSH_SMSG_PUBLIC_KEY);
2106 for (i = 0; i < 8; i++)
2107 packet_put_char(cookie[i]);
2109 /* Store our public server RSA key. */
2110 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2111 packet_put_bignum(sensitive_data.server_key->rsa->e);
2112 packet_put_bignum(sensitive_data.server_key->rsa->n);
2114 /* Store our public host RSA key. */
2115 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2116 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2117 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2119 /* Put protocol flags. */
2120 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2122 /* Declare which ciphers we support. */
2123 packet_put_int(cipher_mask_ssh1(0));
2125 /* Declare supported authentication types. */
2127 if (options.rhosts_rsa_authentication)
2128 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2129 if (options.rsa_authentication)
2130 auth_mask |= 1 << SSH_AUTH_RSA;
2131 if (options.challenge_response_authentication == 1)
2132 auth_mask |= 1 << SSH_AUTH_TIS;
2133 if (options.password_authentication)
2134 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2135 packet_put_int(auth_mask);
2137 /* Send the packet and wait for it to be sent. */
2139 packet_write_wait();
2141 debug("Sent %d bit server key and %d bit host key.",
2142 BN_num_bits(sensitive_data.server_key->rsa->n),
2143 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2145 /* Read clients reply (cipher type and session key). */
2146 packet_read_expect(SSH_CMSG_SESSION_KEY);
2148 /* Get cipher type and check whether we accept this. */
2149 cipher_type = packet_get_char();
2151 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2152 packet_disconnect("Warning: client selects unsupported cipher.");
2154 /* Get check bytes from the packet. These must match those we
2155 sent earlier with the public key packet. */
2156 for (i = 0; i < 8; i++)
2157 if (cookie[i] != packet_get_char())
2158 packet_disconnect("IP Spoofing check bytes do not match.");
2160 debug("Encryption type: %.200s", cipher_name(cipher_type));
2162 /* Get the encrypted integer. */
2163 if ((session_key_int = BN_new()) == NULL)
2164 fatal("do_ssh1_kex: BN_new failed");
2165 packet_get_bignum(session_key_int);
2167 protocol_flags = packet_get_int();
2168 packet_set_protocol_flags(protocol_flags);
2171 /* Decrypt session_key_int using host/server keys */
2172 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2175 * Extract session key from the decrypted integer. The key is in the
2176 * least significant 256 bits of the integer; the first byte of the
2177 * key is in the highest bits.
2180 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2181 len = BN_num_bytes(session_key_int);
2182 if (len < 0 || (u_int)len > sizeof(session_key)) {
2183 error("do_ssh1_kex: bad session key len from %s: "
2184 "session_key_int %d > sizeof(session_key) %lu",
2185 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2188 memset(session_key, 0, sizeof(session_key));
2189 BN_bn2bin(session_key_int,
2190 session_key + sizeof(session_key) - len);
2192 derive_ssh1_session_id(
2193 sensitive_data.ssh1_host_key->rsa->n,
2194 sensitive_data.server_key->rsa->n,
2195 cookie, session_id);
2197 * Xor the first 16 bytes of the session key with the
2200 for (i = 0; i < 16; i++)
2201 session_key[i] ^= session_id[i];
2205 int bytes = BN_num_bytes(session_key_int);
2206 u_char *buf = xmalloc(bytes);
2209 logit("do_connection: generating a fake encryption key");
2210 BN_bn2bin(session_key_int, buf);
2212 MD5_Update(&md, buf, bytes);
2213 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2214 MD5_Final(session_key, &md);
2216 MD5_Update(&md, session_key, 16);
2217 MD5_Update(&md, buf, bytes);
2218 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2219 MD5_Final(session_key + 16, &md);
2220 memset(buf, 0, bytes);
2222 for (i = 0; i < 16; i++)
2223 session_id[i] = session_key[i] ^ session_key[i + 16];
2225 /* Destroy the private and public keys. No longer. */
2226 destroy_sensitive_data();
2229 mm_ssh1_session_id(session_id);
2231 /* Destroy the decrypted integer. It is no longer needed. */
2232 BN_clear_free(session_key_int);
2234 /* Set the session key. From this on all communications will be encrypted. */
2235 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2237 /* Destroy our copy of the session key. It is no longer needed. */
2238 memset(session_key, 0, sizeof(session_key));
2240 debug("Received session key; encryption turned on.");
2242 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2243 packet_start(SSH_SMSG_SUCCESS);
2245 packet_write_wait();
2249 * SSH2 key exchange: diffie-hellman-group1-sha1
2257 debug ("MYFLAG IS %d", myflag);
2258 if (options.ciphers != NULL) {
2259 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2260 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2261 } else if (options.none_enabled == 1) {
2262 debug ("WARNING: None cipher enabled");
2263 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2264 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE;
2266 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2267 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2268 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2269 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2271 if (options.macs != NULL) {
2272 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2273 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2275 if (options.compression == COMP_NONE) {
2276 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2277 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2278 } else if (options.compression == COMP_DELAYED) {
2279 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2280 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2283 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2289 char *newstr = NULL;
2290 orig = myproposal[PROPOSAL_KEX_ALGS];
2293 * If we don't have a host key, then there's no point advertising
2294 * the other key exchange algorithms
2297 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
2300 if (options.gss_keyex)
2301 gss = ssh_gssapi_server_mechanisms();
2306 xasprintf(&newstr, "%s,%s", gss, orig);
2313 * If we've got GSSAPI mechanisms, then we've got the 'null' host
2314 * key alg, but we can't tell people about it unless its the only
2315 * host key algorithm we support
2317 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
2318 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
2321 myproposal[PROPOSAL_KEX_ALGS] = newstr;
2323 fatal("No supported key exchange algorithms");
2327 /* start key exchange */
2328 /* start key exchange */
2329 kex = kex_setup(myproposal);
2330 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2331 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2332 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2333 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2335 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
2336 kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
2337 kex->kex[KEX_GSS_GEX_SHA1] = kexgss_server;
2340 kex->client_version_string=client_version_string;
2341 kex->server_version_string=server_version_string;
2342 kex->load_host_key=&get_hostkey_by_type;
2343 kex->host_key_index=&get_hostkey_index;
2347 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2349 session_id2 = kex->session_id;
2350 session_id2_len = kex->session_id_len;
2353 /* send 1st encrypted/maced/compressed message */
2354 packet_start(SSH2_MSG_IGNORE);
2355 packet_put_cstring("markus");
2357 packet_write_wait();
2362 /* server specific fatal cleanup */
2367 do_cleanup(the_authctxt);
2368 #ifdef SSH_AUDIT_EVENTS
2369 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2370 if (!use_privsep || mm_is_monitor())
2371 audit_event(SSH_CONNECTION_ABANDON);