1 /* $OpenBSD: sshd.c,v 1.374 2010/03/07 11:57:13 dtucker Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This program is the ssh daemon. It listens for connections from clients,
7 * and performs authentication, executes use commands or shell, and forwards
8 * information to/from the application to the user client over an encrypted
9 * connection. This can also handle forwarding of X11, TCP/IP, and
10 * authentication agent connections.
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
18 * SSH2 implementation:
19 * Privilege Separation:
21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22 * Copyright (c) 2002 Niels Provos. All rights reserved.
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
48 #include <sys/types.h>
49 #include <sys/ioctl.h>
51 #include <sys/socket.h>
52 #ifdef HAVE_SYS_STAT_H
53 # include <sys/stat.h>
55 #ifdef HAVE_SYS_TIME_H
56 # include <sys/time.h>
58 #include "openbsd-compat/sys-tree.h"
59 #include "openbsd-compat/sys-queue.h"
78 #include <openssl/dh.h>
79 #include <openssl/bn.h>
80 #include <openssl/md5.h>
81 #include <openssl/rand.h>
82 #include "openbsd-compat/openssl-compat.h"
84 #ifdef HAVE_SECUREWARE
85 #include <sys/security.h>
91 #if defined(GSSAPI) && defined(HAVE_GSSAPI_H)
93 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H)
94 #include <gssapi/gssapi.h>
107 #include "servconf.h"
114 #include "myproposal.h"
115 #include "authfile.h"
116 #include "pathnames.h"
117 #include "atomicio.h"
118 #include "canohost.h"
119 #include "hostfile.h"
123 #include "dispatch.h"
124 #include "channels.h"
126 #include "monitor_mm.h"
131 #include "monitor_wrap.h"
147 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
148 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
149 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
150 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
152 extern char *__progname;
154 /* Server configuration options. */
155 ServerOptions options;
157 /* Name of the server configuration file. */
158 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
161 * Debug mode flag. This can be set on the command line. If debug
162 * mode is enabled, extra debugging output will be sent to the system
163 * log, the daemon will not go to background, and will exit after processing
164 * the first connection.
168 /* Flag indicating that the daemon should only test the configuration and keys. */
171 /* Flag indicating that the daemon is being started from inetd. */
174 /* Flag indicating that sshd should not detach and become a daemon. */
175 int no_daemon_flag = 0;
177 /* debug goes to stderr unless inetd_flag is set */
180 /* Saved arguments to main(). */
185 int rexeced_flag = 0;
191 * The sockets that the server is listening; this is used in the SIGHUP
194 #define MAX_LISTEN_SOCKS 16
195 int listen_socks[MAX_LISTEN_SOCKS];
196 int num_listen_socks = 0;
199 * the client's version string, passed by sshd2 in compat mode. if != NULL,
200 * sshd will skip the version-number exchange
202 char *client_version_string = NULL;
203 char *server_version_string = NULL;
205 /* for rekeying XXX fixme */
209 * Any really sensitive data in the application is contained in this
210 * structure. The idea is that this structure could be locked into memory so
211 * that the pages do not get written into swap. However, there are some
212 * problems. The private key contains BIGNUMs, and we do not (in principle)
213 * have access to the internals of them, and locking just the structure is
214 * not very useful. Currently, memory locking is not implemented.
217 Key *server_key; /* ephemeral server key */
218 Key *ssh1_host_key; /* ssh1 host key */
219 Key **host_keys; /* all private host keys */
220 Key **host_certificates; /* all public host certificates */
223 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
227 * Flag indicating whether the RSA server key needs to be regenerated.
228 * Is set in the SIGALRM handler and cleared when the key is regenerated.
230 static volatile sig_atomic_t key_do_regen = 0;
232 /* This is set to true when a signal is received. */
233 static volatile sig_atomic_t received_sighup = 0;
234 static volatile sig_atomic_t received_sigterm = 0;
236 /* session identifier, used by RSA-auth */
237 u_char session_id[16];
240 u_char *session_id2 = NULL;
241 u_int session_id2_len = 0;
243 /* record remote hostname or ip */
244 u_int utmp_len = UT_HOSTSIZE;
246 /* options.max_startup sized array of fd ints */
247 int *startup_pipes = NULL;
248 int startup_pipe; /* in child */
250 /* variables used for privilege separation */
251 int use_privsep = -1;
252 struct monitor *pmonitor = NULL;
254 /* global authentication context */
255 Authctxt *the_authctxt = NULL;
257 /* sshd_config buffer */
260 /* message to be displayed after login */
263 /* Unprivileged user */
264 struct passwd *privsep_pw = NULL;
266 /* Prototypes for various functions defined later in this file. */
267 void destroy_sensitive_data(void);
268 void demote_sensitive_data(void);
270 static void do_ssh1_kex(void);
271 static void do_ssh2_kex(void);
274 * Close all listening sockets
277 close_listen_socks(void)
281 for (i = 0; i < num_listen_socks; i++)
282 close(listen_socks[i]);
283 num_listen_socks = -1;
287 close_startup_pipes(void)
292 for (i = 0; i < options.max_startups; i++)
293 if (startup_pipes[i] != -1)
294 close(startup_pipes[i]);
298 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
299 * the effect is to reread the configuration file (and to regenerate
305 sighup_handler(int sig)
307 int save_errno = errno;
310 signal(SIGHUP, sighup_handler);
315 * Called from the main program after receiving SIGHUP.
316 * Restarts the server.
321 logit("Received SIGHUP; restarting.");
322 close_listen_socks();
323 close_startup_pipes();
324 alarm(0); /* alarm timer persists across exec */
325 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
326 execv(saved_argv[0], saved_argv);
327 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
333 * Generic signal handler for terminating signals in the master daemon.
337 sigterm_handler(int sig)
339 received_sigterm = sig;
343 * SIGCHLD handler. This is called whenever a child dies. This will then
344 * reap any zombies left by exited children.
348 main_sigchld_handler(int sig)
350 int save_errno = errno;
354 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
355 (pid < 0 && errno == EINTR))
358 signal(SIGCHLD, main_sigchld_handler);
363 * Signal handler for the alarm after the login grace period has expired.
367 grace_alarm_handler(int sig)
369 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
370 kill(pmonitor->m_pid, SIGALRM);
372 /* Log error and exit. */
373 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
377 * Signal handler for the key regeneration alarm. Note that this
378 * alarm only occurs in the daemon waiting for connections, and it does not
379 * do anything with the private key or random state before forking.
380 * Thus there should be no concurrency control/asynchronous execution
384 generate_ephemeral_server_key(void)
386 verbose("Generating %s%d bit RSA key.",
387 sensitive_data.server_key ? "new " : "", options.server_key_bits);
388 if (sensitive_data.server_key != NULL)
389 key_free(sensitive_data.server_key);
390 sensitive_data.server_key = key_generate(KEY_RSA1,
391 options.server_key_bits);
392 verbose("RSA key generation complete.");
394 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
400 key_regeneration_alarm(int sig)
402 int save_errno = errno;
404 signal(SIGALRM, SIG_DFL);
410 sshd_exchange_identification(int sock_in, int sock_out)
414 int remote_major, remote_minor;
416 char *s, *newline = "\n";
417 char buf[256]; /* Must not be larger than remote_version. */
418 char remote_version[256]; /* Must be at least as big as buf. */
420 if ((options.protocol & SSH_PROTO_1) &&
421 (options.protocol & SSH_PROTO_2)) {
422 major = PROTOCOL_MAJOR_1;
424 } else if (options.protocol & SSH_PROTO_2) {
425 major = PROTOCOL_MAJOR_2;
426 minor = PROTOCOL_MINOR_2;
429 major = PROTOCOL_MAJOR_1;
430 minor = PROTOCOL_MINOR_1;
432 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
433 SSH_VERSION, newline);
434 server_version_string = xstrdup(buf);
436 /* Send our protocol version identification. */
437 if (roaming_atomicio(vwrite, sock_out, server_version_string,
438 strlen(server_version_string))
439 != strlen(server_version_string)) {
440 logit("Could not write ident string to %s", get_remote_ipaddr());
444 /* Read other sides version identification. */
445 memset(buf, 0, sizeof(buf));
446 for (i = 0; i < sizeof(buf) - 1; i++) {
447 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
448 logit("Did not receive identification string from %s",
449 get_remote_ipaddr());
452 if (buf[i] == '\r') {
454 /* Kludge for F-Secure Macintosh < 1.0.2 */
456 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
460 if (buf[i] == '\n') {
465 buf[sizeof(buf) - 1] = 0;
466 client_version_string = xstrdup(buf);
469 * Check that the versions match. In future this might accept
470 * several versions and set appropriate flags to handle them.
472 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
473 &remote_major, &remote_minor, remote_version) != 3) {
474 s = "Protocol mismatch.\n";
475 (void) atomicio(vwrite, sock_out, s, strlen(s));
478 logit("Bad protocol version identification '%.100s' from %s",
479 client_version_string, get_remote_ipaddr());
482 debug("Client protocol version %d.%d; client software version %.100s",
483 remote_major, remote_minor, remote_version);
485 compat_datafellows(remote_version);
487 if (datafellows & SSH_BUG_PROBE) {
488 logit("probed from %s with %s. Don't panic.",
489 get_remote_ipaddr(), client_version_string);
493 if (datafellows & SSH_BUG_SCANNER) {
494 logit("scanned from %s with %s. Don't panic.",
495 get_remote_ipaddr(), client_version_string);
500 switch (remote_major) {
502 if (remote_minor == 99) {
503 if (options.protocol & SSH_PROTO_2)
509 if (!(options.protocol & SSH_PROTO_1)) {
513 if (remote_minor < 3) {
514 packet_disconnect("Your ssh version is too old and "
515 "is no longer supported. Please install a newer version.");
516 } else if (remote_minor == 3) {
517 /* note that this disables agent-forwarding */
522 if (options.protocol & SSH_PROTO_2) {
531 chop(server_version_string);
532 debug("Local version string %.200s", server_version_string);
535 s = "Protocol major versions differ.\n";
536 (void) atomicio(vwrite, sock_out, s, strlen(s));
539 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
541 server_version_string, client_version_string);
546 /* Destroy the host and server keys. They will no longer be needed. */
548 destroy_sensitive_data(void)
552 if (sensitive_data.server_key) {
553 key_free(sensitive_data.server_key);
554 sensitive_data.server_key = NULL;
556 for (i = 0; i < options.num_host_key_files; i++) {
557 if (sensitive_data.host_keys[i]) {
558 key_free(sensitive_data.host_keys[i]);
559 sensitive_data.host_keys[i] = NULL;
561 if (sensitive_data.host_certificates[i]) {
562 key_free(sensitive_data.host_certificates[i]);
563 sensitive_data.host_certificates[i] = NULL;
566 sensitive_data.ssh1_host_key = NULL;
567 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
570 /* Demote private to public keys for network child */
572 demote_sensitive_data(void)
577 if (sensitive_data.server_key) {
578 tmp = key_demote(sensitive_data.server_key);
579 key_free(sensitive_data.server_key);
580 sensitive_data.server_key = tmp;
583 for (i = 0; i < options.num_host_key_files; i++) {
584 if (sensitive_data.host_keys[i]) {
585 tmp = key_demote(sensitive_data.host_keys[i]);
586 key_free(sensitive_data.host_keys[i]);
587 sensitive_data.host_keys[i] = tmp;
588 if (tmp->type == KEY_RSA1)
589 sensitive_data.ssh1_host_key = tmp;
591 /* Certs do not need demotion */
594 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
598 privsep_preauth_child(void)
603 /* Enable challenge-response authentication for privilege separation */
604 privsep_challenge_enable();
607 arc4random_buf(rnd, sizeof(rnd));
608 RAND_seed(rnd, sizeof(rnd));
610 /* Demote the private keys to public keys. */
611 demote_sensitive_data();
613 /* Change our root directory */
614 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
615 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
617 if (chdir("/") == -1)
618 fatal("chdir(\"/\"): %s", strerror(errno));
620 /* Drop our privileges */
621 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
622 (u_int)privsep_pw->pw_gid);
624 /* XXX not ready, too heavy after chroot */
625 do_setusercontext(privsep_pw);
627 gidset[0] = privsep_pw->pw_gid;
628 if (setgroups(1, gidset) < 0)
629 fatal("setgroups: %.100s", strerror(errno));
630 permanently_set_uid(privsep_pw);
635 privsep_preauth(Authctxt *authctxt)
640 /* Set up unprivileged child process to deal with network data */
641 pmonitor = monitor_init();
642 /* Store a pointer to the kex for later rekeying */
643 pmonitor->m_pkex = &xxx_kex;
647 fatal("fork of unprivileged child failed");
648 } else if (pid != 0) {
649 debug2("Network child is on pid %ld", (long)pid);
651 close(pmonitor->m_recvfd);
652 pmonitor->m_pid = pid;
653 monitor_child_preauth(authctxt, pmonitor);
654 close(pmonitor->m_sendfd);
657 monitor_sync(pmonitor);
659 /* Wait for the child's exit status */
660 while (waitpid(pid, &status, 0) < 0)
667 close(pmonitor->m_sendfd);
669 /* Demote the child */
670 if (getuid() == 0 || geteuid() == 0)
671 privsep_preauth_child();
672 setproctitle("%s", "[net]");
678 privsep_postauth(Authctxt *authctxt)
682 #ifdef DISABLE_FD_PASSING
685 if (authctxt->pw->pw_uid == 0 || options.use_login) {
687 /* File descriptor passing is broken or root login */
692 /* New socket pair */
693 monitor_reinit(pmonitor);
695 pmonitor->m_pid = fork();
696 if (pmonitor->m_pid == -1)
697 fatal("fork of unprivileged child failed");
698 else if (pmonitor->m_pid != 0) {
699 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
700 close(pmonitor->m_recvfd);
701 buffer_clear(&loginmsg);
702 monitor_child_postauth(pmonitor);
708 close(pmonitor->m_sendfd);
710 /* Demote the private keys to public keys. */
711 demote_sensitive_data();
714 arc4random_buf(rnd, sizeof(rnd));
715 RAND_seed(rnd, sizeof(rnd));
717 /* Drop privileges */
718 do_setusercontext(authctxt->pw);
721 /* It is safe now to apply the key state */
722 monitor_apply_keystate(pmonitor);
725 * Tell the packet layer that authentication was successful, since
726 * this information is not part of the key state.
728 packet_set_authenticated();
732 list_hostkey_types(void)
741 for (i = 0; i < options.num_host_key_files; i++) {
742 key = sensitive_data.host_keys[i];
748 if (buffer_len(&b) > 0)
749 buffer_append(&b, ",", 1);
750 p = key_ssh_name(key);
751 buffer_append(&b, p, strlen(p));
754 /* If the private key has a cert peer, then list that too */
755 key = sensitive_data.host_certificates[i];
761 if (buffer_len(&b) > 0)
762 buffer_append(&b, ",", 1);
763 p = key_ssh_name(key);
764 buffer_append(&b, p, strlen(p));
768 buffer_append(&b, "\0", 1);
769 ret = xstrdup(buffer_ptr(&b));
771 debug("list_hostkey_types: %s", ret);
776 get_hostkey_by_type(int type, int need_private)
781 for (i = 0; i < options.num_host_key_files; i++) {
782 if (type == KEY_RSA_CERT || type == KEY_DSA_CERT)
783 key = sensitive_data.host_certificates[i];
785 key = sensitive_data.host_keys[i];
786 if (key != NULL && key->type == type)
787 return need_private ?
788 sensitive_data.host_keys[i] : key;
794 get_hostkey_public_by_type(int type)
796 return get_hostkey_by_type(type, 0);
800 get_hostkey_private_by_type(int type)
802 return get_hostkey_by_type(type, 1);
806 get_hostkey_by_index(int ind)
808 if (ind < 0 || ind >= options.num_host_key_files)
810 return (sensitive_data.host_keys[ind]);
814 get_hostkey_index(Key *key)
818 for (i = 0; i < options.num_host_key_files; i++) {
819 if (key_is_cert(key)) {
820 if (key == sensitive_data.host_certificates[i])
823 if (key == sensitive_data.host_keys[i])
831 * returns 1 if connection should be dropped, 0 otherwise.
832 * dropping starts at connection #max_startups_begin with a probability
833 * of (max_startups_rate/100). the probability increases linearly until
834 * all connections are dropped for startups > max_startups
837 drop_connection(int startups)
841 if (startups < options.max_startups_begin)
843 if (startups >= options.max_startups)
845 if (options.max_startups_rate == 100)
848 p = 100 - options.max_startups_rate;
849 p *= startups - options.max_startups_begin;
850 p /= options.max_startups - options.max_startups_begin;
851 p += options.max_startups_rate;
852 r = arc4random_uniform(100);
854 debug("drop_connection: p %d, r %d", p, r);
855 return (r < p) ? 1 : 0;
861 fprintf(stderr, "%s, %s\n",
862 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
864 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
865 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
866 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
872 send_rexec_state(int fd, Buffer *conf)
876 debug3("%s: entering fd = %d config len %d", __func__, fd,
880 * Protocol from reexec master to child:
881 * string configuration
882 * u_int ephemeral_key_follows
883 * bignum e (only if ephemeral_key_follows == 1)
889 * string rngseed (only if OpenSSL is not self-seeded)
892 buffer_put_cstring(&m, buffer_ptr(conf));
894 if (sensitive_data.server_key != NULL &&
895 sensitive_data.server_key->type == KEY_RSA1) {
896 buffer_put_int(&m, 1);
897 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
898 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
899 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
900 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
901 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
902 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
904 buffer_put_int(&m, 0);
906 #ifndef OPENSSL_PRNG_ONLY
907 rexec_send_rng_seed(&m);
910 if (ssh_msg_send(fd, 0, &m) == -1)
911 fatal("%s: ssh_msg_send failed", __func__);
915 debug3("%s: done", __func__);
919 recv_rexec_state(int fd, Buffer *conf)
925 debug3("%s: entering fd = %d", __func__, fd);
929 if (ssh_msg_recv(fd, &m) == -1)
930 fatal("%s: ssh_msg_recv failed", __func__);
931 if (buffer_get_char(&m) != 0)
932 fatal("%s: rexec version mismatch", __func__);
934 cp = buffer_get_string(&m, &len);
936 buffer_append(conf, cp, len + 1);
939 if (buffer_get_int(&m)) {
940 if (sensitive_data.server_key != NULL)
941 key_free(sensitive_data.server_key);
942 sensitive_data.server_key = key_new_private(KEY_RSA1);
943 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
944 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
945 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
946 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
947 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
948 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
949 rsa_generate_additional_parameters(
950 sensitive_data.server_key->rsa);
953 #ifndef OPENSSL_PRNG_ONLY
954 rexec_recv_rng_seed(&m);
959 debug3("%s: done", __func__);
962 /* Accept a connection from inetd */
964 server_accept_inetd(int *sock_in, int *sock_out)
970 close(REEXEC_CONFIG_PASS_FD);
971 *sock_in = *sock_out = dup(STDIN_FILENO);
973 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
974 close(REEXEC_STARTUP_PIPE_FD);
977 *sock_in = dup(STDIN_FILENO);
978 *sock_out = dup(STDOUT_FILENO);
981 * We intentionally do not close the descriptors 0, 1, and 2
982 * as our code for setting the descriptors won't work if
983 * ttyfd happens to be one of those.
985 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
986 dup2(fd, STDIN_FILENO);
987 dup2(fd, STDOUT_FILENO);
988 if (fd > STDOUT_FILENO)
991 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
995 * Listen for TCP connections
1000 int ret, listen_sock, on = 1;
1001 struct addrinfo *ai;
1002 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1004 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1005 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1007 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1008 fatal("Too many listen sockets. "
1009 "Enlarge MAX_LISTEN_SOCKS");
1010 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1011 ntop, sizeof(ntop), strport, sizeof(strport),
1012 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1013 error("getnameinfo failed: %.100s",
1014 ssh_gai_strerror(ret));
1017 /* Create socket for listening. */
1018 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1020 if (listen_sock < 0) {
1021 /* kernel may not support ipv6 */
1022 verbose("socket: %.100s", strerror(errno));
1025 if (set_nonblock(listen_sock) == -1) {
1030 * Set socket options.
1031 * Allow local port reuse in TIME_WAIT.
1033 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1034 &on, sizeof(on)) == -1)
1035 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1037 /* Only communicate in IPv6 over AF_INET6 sockets. */
1038 if (ai->ai_family == AF_INET6)
1039 sock_set_v6only(listen_sock);
1041 debug("Bind to port %s on %s.", strport, ntop);
1043 /* Bind the socket to the desired port. */
1044 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1045 error("Bind to port %s on %s failed: %.200s.",
1046 strport, ntop, strerror(errno));
1050 listen_socks[num_listen_socks] = listen_sock;
1053 /* Start listening on the port. */
1054 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1055 fatal("listen on [%s]:%s: %.100s",
1056 ntop, strport, strerror(errno));
1057 logit("Server listening on %s port %s.", ntop, strport);
1059 freeaddrinfo(options.listen_addrs);
1061 if (!num_listen_socks)
1062 fatal("Cannot bind any address.");
1066 * The main TCP accept loop. Note that, for the non-debug case, returns
1067 * from this function are in a forked subprocess.
1070 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1073 int i, j, ret, maxfd;
1074 int key_used = 0, startups = 0;
1075 int startup_p[2] = { -1 , -1 };
1076 struct sockaddr_storage from;
1080 /* setup fd set for accept */
1083 for (i = 0; i < num_listen_socks; i++)
1084 if (listen_socks[i] > maxfd)
1085 maxfd = listen_socks[i];
1086 /* pipes connected to unauthenticated childs */
1087 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1088 for (i = 0; i < options.max_startups; i++)
1089 startup_pipes[i] = -1;
1092 * Stay listening for connections until the system crashes or
1093 * the daemon is killed with a signal.
1096 if (received_sighup)
1100 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1103 for (i = 0; i < num_listen_socks; i++)
1104 FD_SET(listen_socks[i], fdset);
1105 for (i = 0; i < options.max_startups; i++)
1106 if (startup_pipes[i] != -1)
1107 FD_SET(startup_pipes[i], fdset);
1109 /* Wait in select until there is a connection. */
1110 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1111 if (ret < 0 && errno != EINTR)
1112 error("select: %.100s", strerror(errno));
1113 if (received_sigterm) {
1114 logit("Received signal %d; terminating.",
1115 (int) received_sigterm);
1116 close_listen_socks();
1117 unlink(options.pid_file);
1120 if (key_used && key_do_regen) {
1121 generate_ephemeral_server_key();
1128 for (i = 0; i < options.max_startups; i++)
1129 if (startup_pipes[i] != -1 &&
1130 FD_ISSET(startup_pipes[i], fdset)) {
1132 * the read end of the pipe is ready
1133 * if the child has closed the pipe
1134 * after successful authentication
1135 * or if the child has died
1137 close(startup_pipes[i]);
1138 startup_pipes[i] = -1;
1141 for (i = 0; i < num_listen_socks; i++) {
1142 if (!FD_ISSET(listen_socks[i], fdset))
1144 fromlen = sizeof(from);
1145 *newsock = accept(listen_socks[i],
1146 (struct sockaddr *)&from, &fromlen);
1148 if (errno != EINTR && errno != EAGAIN &&
1149 errno != EWOULDBLOCK)
1150 error("accept: %.100s", strerror(errno));
1153 if (unset_nonblock(*newsock) == -1) {
1157 if (drop_connection(startups) == 1) {
1158 debug("drop connection #%d", startups);
1162 if (pipe(startup_p) == -1) {
1167 if (rexec_flag && socketpair(AF_UNIX,
1168 SOCK_STREAM, 0, config_s) == -1) {
1169 error("reexec socketpair: %s",
1172 close(startup_p[0]);
1173 close(startup_p[1]);
1177 for (j = 0; j < options.max_startups; j++)
1178 if (startup_pipes[j] == -1) {
1179 startup_pipes[j] = startup_p[0];
1180 if (maxfd < startup_p[0])
1181 maxfd = startup_p[0];
1187 * Got connection. Fork a child to handle it, unless
1188 * we are in debugging mode.
1192 * In debugging mode. Close the listening
1193 * socket, and start processing the
1194 * connection without forking.
1196 debug("Server will not fork when running in debugging mode.");
1197 close_listen_socks();
1198 *sock_in = *newsock;
1199 *sock_out = *newsock;
1200 close(startup_p[0]);
1201 close(startup_p[1]);
1205 send_rexec_state(config_s[0],
1213 * Normal production daemon. Fork, and have
1214 * the child process the connection. The
1215 * parent continues listening.
1217 platform_pre_fork();
1218 if ((pid = fork()) == 0) {
1220 * Child. Close the listening and
1221 * max_startup sockets. Start using
1222 * the accepted socket. Reinitialize
1223 * logging (since our pid has changed).
1224 * We break out of the loop to handle
1227 platform_post_fork_child();
1228 startup_pipe = startup_p[1];
1229 close_startup_pipes();
1230 close_listen_socks();
1231 *sock_in = *newsock;
1232 *sock_out = *newsock;
1233 log_init(__progname,
1235 options.log_facility,
1242 /* Parent. Stay in the loop. */
1243 platform_post_fork_parent(pid);
1245 error("fork: %.100s", strerror(errno));
1247 debug("Forked child %ld.", (long)pid);
1249 close(startup_p[1]);
1252 send_rexec_state(config_s[0], &cfg);
1258 * Mark that the key has been used (it
1259 * was "given" to the child).
1261 if ((options.protocol & SSH_PROTO_1) &&
1263 /* Schedule server key regeneration alarm. */
1264 signal(SIGALRM, key_regeneration_alarm);
1265 alarm(options.key_regeneration_time);
1272 * Ensure that our random state differs
1273 * from that of the child
1278 /* child process check (or debug mode) */
1279 if (num_listen_socks < 0)
1286 * Main program for the daemon.
1289 main(int ac, char **av)
1291 extern char *optarg;
1293 int opt, i, j, on = 1;
1294 int sock_in = -1, sock_out = -1, newsock = -1;
1295 const char *remote_ip;
1296 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1298 char *line, *p, *cp;
1299 int config_s[2] = { -1 , -1 };
1300 u_int64_t ibytes, obytes;
1305 #ifdef HAVE_SECUREWARE
1306 (void)set_auth_parameters(ac, av);
1308 __progname = ssh_get_progname(av[0]);
1311 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1314 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1315 for (i = 0; i < ac; i++)
1316 saved_argv[i] = xstrdup(av[i]);
1317 saved_argv[i] = NULL;
1319 #ifndef HAVE_SETPROCTITLE
1320 /* Prepare for later setproctitle emulation */
1321 compat_init_setproctitle(ac, av);
1325 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1326 debug("setgroups(): %.200s", strerror(errno));
1328 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1331 /* Initialize configuration options to their default values. */
1332 initialize_server_options(&options);
1334 /* Parse command-line arguments. */
1335 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1338 options.address_family = AF_INET;
1341 options.address_family = AF_INET6;
1344 config_file_name = optarg;
1347 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1348 fprintf(stderr, "too many host certificates.\n");
1351 options.host_cert_files[options.num_host_cert_files++] =
1352 derelativise_path(optarg);
1355 if (debug_flag == 0) {
1357 options.log_level = SYSLOG_LEVEL_DEBUG1;
1358 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1359 options.log_level++;
1381 options.log_level = SYSLOG_LEVEL_QUIET;
1384 options.server_key_bits = (int)strtonum(optarg, 256,
1388 options.ports_from_cmdline = 1;
1389 if (options.num_ports >= MAX_PORTS) {
1390 fprintf(stderr, "too many ports.\n");
1393 options.ports[options.num_ports++] = a2port(optarg);
1394 if (options.ports[options.num_ports-1] <= 0) {
1395 fprintf(stderr, "Bad port number.\n");
1400 if ((options.login_grace_time = convtime(optarg)) == -1) {
1401 fprintf(stderr, "Invalid login grace time.\n");
1406 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1407 fprintf(stderr, "Invalid key regeneration interval.\n");
1412 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1413 fprintf(stderr, "too many host keys.\n");
1416 options.host_key_files[options.num_host_key_files++] =
1417 derelativise_path(optarg);
1427 while ((p = strsep(&cp, ",")) && *p != '\0') {
1428 if (strncmp(p, "addr=", 5) == 0)
1429 test_addr = xstrdup(p + 5);
1430 else if (strncmp(p, "host=", 5) == 0)
1431 test_host = xstrdup(p + 5);
1432 else if (strncmp(p, "user=", 5) == 0)
1433 test_user = xstrdup(p + 5);
1435 fprintf(stderr, "Invalid test "
1436 "mode specification %s\n", p);
1442 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1443 if (utmp_len > MAXHOSTNAMELEN) {
1444 fprintf(stderr, "Invalid utmp length.\n");
1449 line = xstrdup(optarg);
1450 if (process_server_config_line(&options, line,
1451 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1461 if (rexeced_flag || inetd_flag)
1463 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1464 fatal("sshd re-exec requires execution with an absolute path");
1466 closefrom(REEXEC_MIN_FREE_FD);
1468 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1470 SSLeay_add_all_algorithms();
1473 * Force logging to stderr until we have loaded the private host
1474 * key (unless started from inetd)
1476 log_init(__progname,
1477 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1478 SYSLOG_LEVEL_INFO : options.log_level,
1479 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1480 SYSLOG_FACILITY_AUTH : options.log_facility,
1481 log_stderr || !inetd_flag);
1484 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1485 * root's environment
1487 if (getenv("KRB5CCNAME") != NULL)
1488 unsetenv("KRB5CCNAME");
1491 /* Cray can define user privs drop all privs now!
1492 * Not needed on PRIV_SU systems!
1497 sensitive_data.server_key = NULL;
1498 sensitive_data.ssh1_host_key = NULL;
1499 sensitive_data.have_ssh1_key = 0;
1500 sensitive_data.have_ssh2_key = 0;
1503 * If we're doing an extended config test, make sure we have all of
1504 * the parameters we need. If we're not doing an extended test,
1505 * do not silently ignore connection test params.
1507 if (test_flag >= 2 &&
1508 (test_user != NULL || test_host != NULL || test_addr != NULL)
1509 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1510 fatal("user, host and addr are all required when testing "
1512 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1514 fatal("Config test connection parameter (-C) provided without "
1517 /* Fetch our configuration */
1520 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1522 load_server_config(config_file_name, &cfg);
1524 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1525 &cfg, NULL, NULL, NULL);
1529 /* Fill in default values for those options not explicitly set. */
1530 fill_default_server_options(&options);
1532 /* challenge-response is implemented via keyboard interactive */
1533 if (options.challenge_response_authentication)
1534 options.kbd_interactive_authentication = 1;
1536 /* set default channel AF */
1537 channel_set_af(options.address_family);
1539 /* Check that there are no remaining arguments. */
1541 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1545 debug("sshd version %.100s", SSH_RELEASE);
1547 /* Store privilege separation user for later use if required. */
1548 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1549 if (use_privsep || options.kerberos_authentication)
1550 fatal("Privilege separation user %s does not exist",
1553 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1554 privsep_pw = pwcopy(privsep_pw);
1555 xfree(privsep_pw->pw_passwd);
1556 privsep_pw->pw_passwd = xstrdup("*");
1560 /* load private host keys */
1561 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1563 for (i = 0; i < options.num_host_key_files; i++)
1564 sensitive_data.host_keys[i] = NULL;
1566 for (i = 0; i < options.num_host_key_files; i++) {
1567 key = key_load_private(options.host_key_files[i], "", NULL);
1568 sensitive_data.host_keys[i] = key;
1570 error("Could not load host key: %s",
1571 options.host_key_files[i]);
1572 sensitive_data.host_keys[i] = NULL;
1575 switch (key->type) {
1577 sensitive_data.ssh1_host_key = key;
1578 sensitive_data.have_ssh1_key = 1;
1582 sensitive_data.have_ssh2_key = 1;
1585 debug("private host key: #%d type %d %s", i, key->type,
1588 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1589 logit("Disabling protocol version 1. Could not load host key");
1590 options.protocol &= ~SSH_PROTO_1;
1592 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1593 logit("Disabling protocol version 2. Could not load host key");
1594 options.protocol &= ~SSH_PROTO_2;
1596 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1597 logit("sshd: no hostkeys available -- exiting.");
1602 * Load certificates. They are stored in an array at identical
1603 * indices to the public keys that they relate to.
1605 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1607 for (i = 0; i < options.num_host_key_files; i++)
1608 sensitive_data.host_certificates[i] = NULL;
1610 for (i = 0; i < options.num_host_cert_files; i++) {
1611 key = key_load_public(options.host_cert_files[i], NULL);
1613 error("Could not load host certificate: %s",
1614 options.host_cert_files[i]);
1617 if (!key_is_cert(key)) {
1618 error("Certificate file is not a certificate: %s",
1619 options.host_cert_files[i]);
1623 /* Find matching private key */
1624 for (j = 0; j < options.num_host_key_files; j++) {
1625 if (key_equal_public(key,
1626 sensitive_data.host_keys[j])) {
1627 sensitive_data.host_certificates[j] = key;
1631 if (j >= options.num_host_key_files) {
1632 error("No matching private key for certificate: %s",
1633 options.host_cert_files[i]);
1637 sensitive_data.host_certificates[j] = key;
1638 debug("host certificate: #%d type %d %s", j, key->type,
1641 /* Check certain values for sanity. */
1642 if (options.protocol & SSH_PROTO_1) {
1643 if (options.server_key_bits < 512 ||
1644 options.server_key_bits > 32768) {
1645 fprintf(stderr, "Bad server key size.\n");
1649 * Check that server and host key lengths differ sufficiently. This
1650 * is necessary to make double encryption work with rsaref. Oh, I
1651 * hate software patents. I dont know if this can go? Niels
1653 if (options.server_key_bits >
1654 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1655 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1656 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1657 SSH_KEY_BITS_RESERVED) {
1658 options.server_key_bits =
1659 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1660 SSH_KEY_BITS_RESERVED;
1661 debug("Forcing server key to %d bits to make it differ from host key.",
1662 options.server_key_bits);
1669 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1670 (S_ISDIR(st.st_mode) == 0))
1671 fatal("Missing privilege separation directory: %s",
1672 _PATH_PRIVSEP_CHROOT_DIR);
1675 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1676 (st.st_uid != getuid () ||
1677 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1679 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1681 fatal("%s must be owned by root and not group or "
1682 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1685 if (test_flag > 1) {
1686 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1687 parse_server_match_config(&options, test_user,
1688 test_host, test_addr);
1689 dump_config(&options);
1692 /* Configuration looks good, so exit if in test mode. */
1697 * Clear out any supplemental groups we may have inherited. This
1698 * prevents inadvertent creation of files with bad modes (in the
1699 * portable version at least, it's certainly possible for PAM
1700 * to create a file, and we can't control the code in every
1701 * module which might be used).
1703 if (setgroups(0, NULL) < 0)
1704 debug("setgroups() failed: %.200s", strerror(errno));
1707 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1708 for (i = 0; i < rexec_argc; i++) {
1709 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1710 rexec_argv[i] = saved_argv[i];
1712 rexec_argv[rexec_argc] = "-R";
1713 rexec_argv[rexec_argc + 1] = NULL;
1716 /* Ensure that umask disallows at least group and world write */
1717 new_umask = umask(0077) | 0022;
1718 (void) umask(new_umask);
1720 /* Initialize the log (it is reinitialized below in case we forked). */
1721 if (debug_flag && (!inetd_flag || rexeced_flag))
1723 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1726 * If not in debugging mode, and not started from inetd, disconnect
1727 * from the controlling terminal, and fork. The original process
1730 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1733 #endif /* TIOCNOTTY */
1734 if (daemon(0, 0) < 0)
1735 fatal("daemon() failed: %.200s", strerror(errno));
1737 /* Disconnect from the controlling tty. */
1739 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1741 (void) ioctl(fd, TIOCNOTTY, NULL);
1744 #endif /* TIOCNOTTY */
1746 /* Reinitialize the log (because of the fork above). */
1747 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1749 /* Avoid killing the process in high-pressure swapping environments. */
1750 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0)
1751 debug("madvise(): %.200s", strerror(errno));
1753 /* Initialize the random number generator. */
1756 /* Chdir to the root directory so that the current disk can be
1757 unmounted if desired. */
1760 /* ignore SIGPIPE */
1761 signal(SIGPIPE, SIG_IGN);
1763 /* Get a connection, either from inetd or a listening TCP socket */
1765 server_accept_inetd(&sock_in, &sock_out);
1767 platform_pre_listen();
1770 if (options.protocol & SSH_PROTO_1)
1771 generate_ephemeral_server_key();
1773 signal(SIGHUP, sighup_handler);
1774 signal(SIGCHLD, main_sigchld_handler);
1775 signal(SIGTERM, sigterm_handler);
1776 signal(SIGQUIT, sigterm_handler);
1779 * Write out the pid file after the sigterm handler
1780 * is setup and the listen sockets are bound
1783 FILE *f = fopen(options.pid_file, "w");
1786 error("Couldn't create pid file \"%s\": %s",
1787 options.pid_file, strerror(errno));
1789 fprintf(f, "%ld\n", (long) getpid());
1794 /* Accept a connection and return in a forked child */
1795 server_accept_loop(&sock_in, &sock_out,
1796 &newsock, config_s);
1799 /* This is the child processing a new connection. */
1800 setproctitle("%s", "[accepted]");
1803 * Create a new session and process group since the 4.4BSD
1804 * setlogin() affects the entire process group. We don't
1805 * want the child to be able to affect the parent.
1807 #if !defined(SSHD_ACQUIRES_CTTY)
1809 * If setsid is called, on some platforms sshd will later acquire a
1810 * controlling terminal which will result in "could not set
1811 * controlling tty" errors.
1813 if (!debug_flag && !inetd_flag && setsid() < 0)
1814 error("setsid: %.100s", strerror(errno));
1820 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1821 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1822 dup2(newsock, STDIN_FILENO);
1823 dup2(STDIN_FILENO, STDOUT_FILENO);
1824 if (startup_pipe == -1)
1825 close(REEXEC_STARTUP_PIPE_FD);
1827 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1829 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1831 if (startup_pipe != -1)
1832 close(startup_pipe);
1834 execv(rexec_argv[0], rexec_argv);
1836 /* Reexec has failed, fall back and continue */
1837 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1838 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1839 log_init(__progname, options.log_level,
1840 options.log_facility, log_stderr);
1843 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1845 close(REEXEC_CONFIG_PASS_FD);
1846 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1847 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1848 dup2(fd, STDIN_FILENO);
1849 dup2(fd, STDOUT_FILENO);
1850 if (fd > STDERR_FILENO)
1853 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1854 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1857 /* Executed child processes don't need these. */
1858 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1859 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1862 * Disable the key regeneration alarm. We will not regenerate the
1863 * key since we are no longer in a position to give it to anyone. We
1864 * will not restart on SIGHUP since it no longer makes sense.
1867 signal(SIGALRM, SIG_DFL);
1868 signal(SIGHUP, SIG_DFL);
1869 signal(SIGTERM, SIG_DFL);
1870 signal(SIGQUIT, SIG_DFL);
1871 signal(SIGCHLD, SIG_DFL);
1872 signal(SIGINT, SIG_DFL);
1876 * Initialize the resolver. This may not happen automatically
1877 * before privsep chroot().
1879 if ((_res.options & RES_INIT) == 0) {
1880 debug("res_init()");
1885 * Force GSS-API to parse its configuration and load any
1886 * mechanism plugins.
1890 OM_uint32 minor_status;
1891 gss_indicate_mechs(&minor_status, &mechs);
1892 gss_release_oid_set(&minor_status, &mechs);
1898 * Register our connection. This turns encryption off because we do
1901 packet_set_connection(sock_in, sock_out);
1902 packet_set_server();
1904 /* Set SO_KEEPALIVE if requested. */
1905 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1906 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1907 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1909 if ((remote_port = get_remote_port()) < 0) {
1910 debug("get_remote_port failed");
1915 * We use get_canonical_hostname with usedns = 0 instead of
1916 * get_remote_ipaddr here so IP options will be checked.
1918 (void) get_canonical_hostname(0);
1920 * The rest of the code depends on the fact that
1921 * get_remote_ipaddr() caches the remote ip, even if
1922 * the socket goes away.
1924 remote_ip = get_remote_ipaddr();
1926 #ifdef SSH_AUDIT_EVENTS
1927 audit_connection_from(remote_ip, remote_port);
1930 allow_severity = options.log_facility|LOG_INFO;
1931 deny_severity = options.log_facility|LOG_WARNING;
1932 /* Check whether logins are denied from this host. */
1933 if (packet_connection_is_on_socket()) {
1934 struct request_info req;
1936 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1939 if (!hosts_access(&req)) {
1940 debug("Connection refused by tcp wrapper");
1943 fatal("libwrap refuse returns");
1946 #endif /* LIBWRAP */
1948 /* Log the connection. */
1949 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1952 * We don't want to listen forever unless the other side
1953 * successfully authenticates itself. So we set up an alarm which is
1954 * cleared after successful authentication. A limit of zero
1955 * indicates no limit. Note that we don't set the alarm in debugging
1956 * mode; it is just annoying to have the server exit just when you
1957 * are about to discover the bug.
1959 signal(SIGALRM, grace_alarm_handler);
1961 alarm(options.login_grace_time);
1963 sshd_exchange_identification(sock_in, sock_out);
1965 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1966 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1967 generate_ephemeral_server_key();
1969 packet_set_nonblocking();
1971 /* allocate authentication context */
1972 authctxt = xcalloc(1, sizeof(*authctxt));
1974 authctxt->loginmsg = &loginmsg;
1976 /* XXX global for cleanup, access from other modules */
1977 the_authctxt = authctxt;
1979 /* prepare buffer to collect messages to display to user after login */
1980 buffer_init(&loginmsg);
1984 if (privsep_preauth(authctxt) == 1)
1987 /* perform the key exchange */
1988 /* authenticate user and start session */
1991 do_authentication2(authctxt);
1994 do_authentication(authctxt);
1997 * If we use privilege separation, the unprivileged child transfers
1998 * the current keystate and exits
2001 mm_send_keystate(pmonitor);
2007 * Cancel the alarm we set to limit the time taken for
2011 signal(SIGALRM, SIG_DFL);
2012 authctxt->authenticated = 1;
2013 if (startup_pipe != -1) {
2014 close(startup_pipe);
2018 #ifdef SSH_AUDIT_EVENTS
2019 audit_event(SSH_AUTH_SUCCESS);
2023 if (options.gss_authentication) {
2024 temporarily_use_uid(authctxt->pw);
2025 ssh_gssapi_storecreds();
2030 if (options.use_pam) {
2037 * In privilege separation, we fork another child and prepare
2038 * file descriptor passing.
2041 privsep_postauth(authctxt);
2042 /* the monitor process [priv] will not return */
2044 destroy_sensitive_data();
2047 packet_set_timeout(options.client_alive_interval,
2048 options.client_alive_count_max);
2050 /* Start session. */
2051 do_authenticated(authctxt);
2053 /* The connection has been terminated. */
2054 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2055 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2056 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
2058 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2061 if (options.use_pam)
2063 #endif /* USE_PAM */
2065 #ifdef SSH_AUDIT_EVENTS
2066 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2078 * Decrypt session_key_int using our private server key and private host key
2079 * (key with larger modulus first).
2082 ssh1_session_key(BIGNUM *session_key_int)
2086 if (BN_cmp(sensitive_data.server_key->rsa->n,
2087 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2088 /* Server key has bigger modulus. */
2089 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2090 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2091 SSH_KEY_BITS_RESERVED) {
2092 fatal("do_connection: %s: "
2093 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2094 get_remote_ipaddr(),
2095 BN_num_bits(sensitive_data.server_key->rsa->n),
2096 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2097 SSH_KEY_BITS_RESERVED);
2099 if (rsa_private_decrypt(session_key_int, session_key_int,
2100 sensitive_data.server_key->rsa) <= 0)
2102 if (rsa_private_decrypt(session_key_int, session_key_int,
2103 sensitive_data.ssh1_host_key->rsa) <= 0)
2106 /* Host key has bigger modulus (or they are equal). */
2107 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2108 BN_num_bits(sensitive_data.server_key->rsa->n) +
2109 SSH_KEY_BITS_RESERVED) {
2110 fatal("do_connection: %s: "
2111 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2112 get_remote_ipaddr(),
2113 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2114 BN_num_bits(sensitive_data.server_key->rsa->n),
2115 SSH_KEY_BITS_RESERVED);
2117 if (rsa_private_decrypt(session_key_int, session_key_int,
2118 sensitive_data.ssh1_host_key->rsa) < 0)
2120 if (rsa_private_decrypt(session_key_int, session_key_int,
2121 sensitive_data.server_key->rsa) < 0)
2134 BIGNUM *session_key_int;
2135 u_char session_key[SSH_SESSION_KEY_LENGTH];
2137 u_int cipher_type, auth_mask, protocol_flags;
2140 * Generate check bytes that the client must send back in the user
2141 * packet in order for it to be accepted; this is used to defy ip
2142 * spoofing attacks. Note that this only works against somebody
2143 * doing IP spoofing from a remote machine; any machine on the local
2144 * network can still see outgoing packets and catch the random
2145 * cookie. This only affects rhosts authentication, and this is one
2146 * of the reasons why it is inherently insecure.
2148 arc4random_buf(cookie, sizeof(cookie));
2151 * Send our public key. We include in the packet 64 bits of random
2152 * data that must be matched in the reply in order to prevent IP
2155 packet_start(SSH_SMSG_PUBLIC_KEY);
2156 for (i = 0; i < 8; i++)
2157 packet_put_char(cookie[i]);
2159 /* Store our public server RSA key. */
2160 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2161 packet_put_bignum(sensitive_data.server_key->rsa->e);
2162 packet_put_bignum(sensitive_data.server_key->rsa->n);
2164 /* Store our public host RSA key. */
2165 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2166 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2167 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2169 /* Put protocol flags. */
2170 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2172 /* Declare which ciphers we support. */
2173 packet_put_int(cipher_mask_ssh1(0));
2175 /* Declare supported authentication types. */
2177 if (options.rhosts_rsa_authentication)
2178 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2179 if (options.rsa_authentication)
2180 auth_mask |= 1 << SSH_AUTH_RSA;
2181 if (options.challenge_response_authentication == 1)
2182 auth_mask |= 1 << SSH_AUTH_TIS;
2183 if (options.password_authentication)
2184 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2185 packet_put_int(auth_mask);
2187 /* Send the packet and wait for it to be sent. */
2189 packet_write_wait();
2191 debug("Sent %d bit server key and %d bit host key.",
2192 BN_num_bits(sensitive_data.server_key->rsa->n),
2193 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2195 /* Read clients reply (cipher type and session key). */
2196 packet_read_expect(SSH_CMSG_SESSION_KEY);
2198 /* Get cipher type and check whether we accept this. */
2199 cipher_type = packet_get_char();
2201 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2202 packet_disconnect("Warning: client selects unsupported cipher.");
2204 /* Get check bytes from the packet. These must match those we
2205 sent earlier with the public key packet. */
2206 for (i = 0; i < 8; i++)
2207 if (cookie[i] != packet_get_char())
2208 packet_disconnect("IP Spoofing check bytes do not match.");
2210 debug("Encryption type: %.200s", cipher_name(cipher_type));
2212 /* Get the encrypted integer. */
2213 if ((session_key_int = BN_new()) == NULL)
2214 fatal("do_ssh1_kex: BN_new failed");
2215 packet_get_bignum(session_key_int);
2217 protocol_flags = packet_get_int();
2218 packet_set_protocol_flags(protocol_flags);
2221 /* Decrypt session_key_int using host/server keys */
2222 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2225 * Extract session key from the decrypted integer. The key is in the
2226 * least significant 256 bits of the integer; the first byte of the
2227 * key is in the highest bits.
2230 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2231 len = BN_num_bytes(session_key_int);
2232 if (len < 0 || (u_int)len > sizeof(session_key)) {
2233 error("do_ssh1_kex: bad session key len from %s: "
2234 "session_key_int %d > sizeof(session_key) %lu",
2235 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2238 memset(session_key, 0, sizeof(session_key));
2239 BN_bn2bin(session_key_int,
2240 session_key + sizeof(session_key) - len);
2242 derive_ssh1_session_id(
2243 sensitive_data.ssh1_host_key->rsa->n,
2244 sensitive_data.server_key->rsa->n,
2245 cookie, session_id);
2247 * Xor the first 16 bytes of the session key with the
2250 for (i = 0; i < 16; i++)
2251 session_key[i] ^= session_id[i];
2255 int bytes = BN_num_bytes(session_key_int);
2256 u_char *buf = xmalloc(bytes);
2259 logit("do_connection: generating a fake encryption key");
2260 BN_bn2bin(session_key_int, buf);
2262 MD5_Update(&md, buf, bytes);
2263 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2264 MD5_Final(session_key, &md);
2266 MD5_Update(&md, session_key, 16);
2267 MD5_Update(&md, buf, bytes);
2268 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2269 MD5_Final(session_key + 16, &md);
2270 memset(buf, 0, bytes);
2272 for (i = 0; i < 16; i++)
2273 session_id[i] = session_key[i] ^ session_key[i + 16];
2275 /* Destroy the private and public keys. No longer. */
2276 destroy_sensitive_data();
2279 mm_ssh1_session_id(session_id);
2281 /* Destroy the decrypted integer. It is no longer needed. */
2282 BN_clear_free(session_key_int);
2284 /* Set the session key. From this on all communications will be encrypted. */
2285 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2287 /* Destroy our copy of the session key. It is no longer needed. */
2288 memset(session_key, 0, sizeof(session_key));
2290 debug("Received session key; encryption turned on.");
2292 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2293 packet_start(SSH_SMSG_SUCCESS);
2295 packet_write_wait();
2299 * SSH2 key exchange: diffie-hellman-group1-sha1
2306 if (options.ciphers != NULL) {
2307 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2308 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2310 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2311 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2312 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2313 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2315 if (options.macs != NULL) {
2316 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2317 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2319 if (options.compression == COMP_NONE) {
2320 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2321 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2322 } else if (options.compression == COMP_DELAYED) {
2323 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2324 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2327 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2329 /* start key exchange */
2330 kex = kex_setup(myproposal);
2331 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2332 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2333 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2334 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2336 kex->client_version_string=client_version_string;
2337 kex->server_version_string=server_version_string;
2338 kex->load_host_public_key=&get_hostkey_public_by_type;
2339 kex->load_host_private_key=&get_hostkey_private_by_type;
2340 kex->host_key_index=&get_hostkey_index;
2344 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2346 session_id2 = kex->session_id;
2347 session_id2_len = kex->session_id_len;
2350 /* send 1st encrypted/maced/compressed message */
2351 packet_start(SSH2_MSG_IGNORE);
2352 packet_put_cstring("markus");
2354 packet_write_wait();
2359 /* server specific fatal cleanup */
2364 do_cleanup(the_authctxt);
2365 #ifdef SSH_AUDIT_EVENTS
2366 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2367 if (!use_privsep || mm_is_monitor())
2368 audit_event(SSH_CONNECTION_ABANDON);