1 /* $OpenBSD: sshd.c,v 1.393 2012/07/10 02:19:15 djm Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This program is the ssh daemon. It listens for connections from clients,
7 * and performs authentication, executes use commands or shell, and forwards
8 * information to/from the application to the user client over an encrypted
9 * connection. This can also handle forwarding of X11, TCP/IP, and
10 * authentication agent connections.
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
18 * SSH2 implementation:
19 * Privilege Separation:
21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22 * Copyright (c) 2002 Niels Provos. All rights reserved.
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
47 #include <sys/types.h>
48 #include <sys/ioctl.h>
49 #include <sys/socket.h>
50 #ifdef HAVE_SYS_STAT_H
51 # include <sys/stat.h>
53 #ifdef HAVE_SYS_TIME_H
54 # include <sys/time.h>
56 #include "openbsd-compat/sys-tree.h"
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>
103 #include "myproposal.h"
104 #include "authfile.h"
105 #include "pathnames.h"
106 #include "atomicio.h"
107 #include "canohost.h"
108 #include "hostfile.h"
112 #include "dispatch.h"
113 #include "channels.h"
115 #include "monitor_mm.h"
120 #include "monitor_wrap.h"
122 #include "ssh-sandbox.h"
137 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
138 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
139 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
140 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
145 extern char *__progname;
147 /* Server configuration options. */
148 ServerOptions options;
150 /* Name of the server configuration file. */
151 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
154 * Debug mode flag. This can be set on the command line. If debug
155 * mode is enabled, extra debugging output will be sent to the system
156 * log, the daemon will not go to background, and will exit after processing
157 * the first connection.
161 /* Flag indicating that the daemon should only test the configuration and keys. */
164 /* Flag indicating that the daemon is being started from inetd. */
167 /* Flag indicating that sshd should not detach and become a daemon. */
168 int no_daemon_flag = 0;
170 /* debug goes to stderr unless inetd_flag is set */
173 /* Saved arguments to main(). */
178 int rexeced_flag = 0;
184 * The sockets that the server is listening; this is used in the SIGHUP
187 #define MAX_LISTEN_SOCKS 16
188 int listen_socks[MAX_LISTEN_SOCKS];
189 int num_listen_socks = 0;
192 * the client's version string, passed by sshd2 in compat mode. if != NULL,
193 * sshd will skip the version-number exchange
195 char *client_version_string = NULL;
196 char *server_version_string = NULL;
198 /* for rekeying XXX fixme */
202 * Any really sensitive data in the application is contained in this
203 * structure. The idea is that this structure could be locked into memory so
204 * that the pages do not get written into swap. However, there are some
205 * problems. The private key contains BIGNUMs, and we do not (in principle)
206 * have access to the internals of them, and locking just the structure is
207 * not very useful. Currently, memory locking is not implemented.
210 Key *server_key; /* ephemeral server key */
211 Key *ssh1_host_key; /* ssh1 host key */
212 Key **host_keys; /* all private host keys */
213 Key **host_certificates; /* all public host certificates */
216 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
220 * Flag indicating whether the RSA server key needs to be regenerated.
221 * Is set in the SIGALRM handler and cleared when the key is regenerated.
223 static volatile sig_atomic_t key_do_regen = 0;
225 /* This is set to true when a signal is received. */
226 static volatile sig_atomic_t received_sighup = 0;
227 static volatile sig_atomic_t received_sigterm = 0;
229 /* session identifier, used by RSA-auth */
230 u_char session_id[16];
233 u_char *session_id2 = NULL;
234 u_int session_id2_len = 0;
236 /* record remote hostname or ip */
237 u_int utmp_len = MAXHOSTNAMELEN;
239 /* options.max_startup sized array of fd ints */
240 int *startup_pipes = NULL;
241 int startup_pipe; /* in child */
243 /* variables used for privilege separation */
244 int use_privsep = -1;
245 struct monitor *pmonitor = NULL;
246 int privsep_is_preauth = 1;
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 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
320 execv(saved_argv[0], saved_argv);
321 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
327 * Generic signal handler for terminating signals in the master daemon.
331 sigterm_handler(int sig)
333 received_sigterm = sig;
337 * SIGCHLD handler. This is called whenever a child dies. This will then
338 * reap any zombies left by exited children.
342 main_sigchld_handler(int sig)
344 int save_errno = errno;
348 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
349 (pid < 0 && errno == EINTR))
352 signal(SIGCHLD, main_sigchld_handler);
357 * Signal handler for the alarm after the login grace period has expired.
361 grace_alarm_handler(int sig)
363 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
364 kill(pmonitor->m_pid, SIGALRM);
366 /* Log error and exit. */
367 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
371 * Signal handler for the key regeneration alarm. Note that this
372 * alarm only occurs in the daemon waiting for connections, and it does not
373 * do anything with the private key or random state before forking.
374 * Thus there should be no concurrency control/asynchronous execution
378 generate_ephemeral_server_key(void)
380 verbose("Generating %s%d bit RSA key.",
381 sensitive_data.server_key ? "new " : "", options.server_key_bits);
382 if (sensitive_data.server_key != NULL)
383 key_free(sensitive_data.server_key);
384 sensitive_data.server_key = key_generate(KEY_RSA1,
385 options.server_key_bits);
386 verbose("RSA key generation complete.");
388 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
394 key_regeneration_alarm(int sig)
396 int save_errno = errno;
398 signal(SIGALRM, SIG_DFL);
404 sshd_exchange_identification(int sock_in, int sock_out)
408 int remote_major, remote_minor;
410 char *s, *newline = "\n";
411 char buf[256]; /* Must not be larger than remote_version. */
412 char remote_version[256]; /* Must be at least as big as buf. */
414 if ((options.protocol & SSH_PROTO_1) &&
415 (options.protocol & SSH_PROTO_2)) {
416 major = PROTOCOL_MAJOR_1;
418 } else if (options.protocol & SSH_PROTO_2) {
419 major = PROTOCOL_MAJOR_2;
420 minor = PROTOCOL_MINOR_2;
423 major = PROTOCOL_MAJOR_1;
424 minor = PROTOCOL_MINOR_1;
427 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s",
428 major, minor, SSH_VERSION,
429 *options.version_addendum == '\0' ? "" : " ",
430 options.version_addendum, newline);
432 /* Send our protocol version identification. */
433 if (roaming_atomicio(vwrite, sock_out, server_version_string,
434 strlen(server_version_string))
435 != strlen(server_version_string)) {
436 logit("Could not write ident string to %s", get_remote_ipaddr());
440 /* Read other sides version identification. */
441 memset(buf, 0, sizeof(buf));
442 for (i = 0; i < sizeof(buf) - 1; i++) {
443 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
444 logit("Did not receive identification string from %s",
445 get_remote_ipaddr());
448 if (buf[i] == '\r') {
450 /* Kludge for F-Secure Macintosh < 1.0.2 */
452 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
456 if (buf[i] == '\n') {
461 buf[sizeof(buf) - 1] = 0;
462 client_version_string = xstrdup(buf);
465 * Check that the versions match. In future this might accept
466 * several versions and set appropriate flags to handle them.
468 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
469 &remote_major, &remote_minor, remote_version) != 3) {
470 s = "Protocol mismatch.\n";
471 (void) atomicio(vwrite, sock_out, s, strlen(s));
474 logit("Bad protocol version identification '%.100s' from %s",
475 client_version_string, get_remote_ipaddr());
478 debug("Client protocol version %d.%d; client software version %.100s",
479 remote_major, remote_minor, remote_version);
480 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s",
481 get_remote_ipaddr(), get_remote_port(),
482 remote_major, remote_minor, remote_version);
484 compat_datafellows(remote_version);
486 if (datafellows & SSH_BUG_PROBE) {
487 logit("probed from %s with %s. Don't panic.",
488 get_remote_ipaddr(), client_version_string);
492 if (datafellows & SSH_BUG_SCANNER) {
493 logit("scanned from %s with %s. Don't panic.",
494 get_remote_ipaddr(), client_version_string);
499 switch (remote_major) {
501 if (remote_minor == 99) {
502 if (options.protocol & SSH_PROTO_2)
508 if (!(options.protocol & SSH_PROTO_1)) {
512 if (remote_minor < 3) {
513 packet_disconnect("Your ssh version is too old and "
514 "is no longer supported. Please install a newer version.");
515 } else if (remote_minor == 3) {
516 /* note that this disables agent-forwarding */
521 if (options.protocol & SSH_PROTO_2) {
530 chop(server_version_string);
531 debug("Local version string %.200s", server_version_string);
534 s = "Protocol major versions differ.\n";
535 (void) atomicio(vwrite, sock_out, s, strlen(s));
538 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
540 server_version_string, client_version_string);
545 /* Destroy the host and server keys. They will no longer be needed. */
547 destroy_sensitive_data(void)
551 if (sensitive_data.server_key) {
552 key_free(sensitive_data.server_key);
553 sensitive_data.server_key = NULL;
555 for (i = 0; i < options.num_host_key_files; i++) {
556 if (sensitive_data.host_keys[i]) {
557 key_free(sensitive_data.host_keys[i]);
558 sensitive_data.host_keys[i] = NULL;
560 if (sensitive_data.host_certificates[i]) {
561 key_free(sensitive_data.host_certificates[i]);
562 sensitive_data.host_certificates[i] = NULL;
565 sensitive_data.ssh1_host_key = NULL;
566 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
569 /* Demote private to public keys for network child */
571 demote_sensitive_data(void)
576 if (sensitive_data.server_key) {
577 tmp = key_demote(sensitive_data.server_key);
578 key_free(sensitive_data.server_key);
579 sensitive_data.server_key = tmp;
582 for (i = 0; i < options.num_host_key_files; i++) {
583 if (sensitive_data.host_keys[i]) {
584 tmp = key_demote(sensitive_data.host_keys[i]);
585 key_free(sensitive_data.host_keys[i]);
586 sensitive_data.host_keys[i] = tmp;
587 if (tmp->type == KEY_RSA1)
588 sensitive_data.ssh1_host_key = tmp;
590 /* Certs do not need demotion */
593 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
597 privsep_preauth_child(void)
602 /* Enable challenge-response authentication for privilege separation */
603 privsep_challenge_enable();
606 arc4random_buf(rnd, sizeof(rnd));
607 RAND_seed(rnd, sizeof(rnd));
609 /* Demote the private keys to public keys. */
610 demote_sensitive_data();
612 /* Change our root directory */
613 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
614 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
616 if (chdir("/") == -1)
617 fatal("chdir(\"/\"): %s", strerror(errno));
619 /* Drop our privileges */
620 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
621 (u_int)privsep_pw->pw_gid);
623 /* XXX not ready, too heavy after chroot */
624 do_setusercontext(privsep_pw);
626 gidset[0] = privsep_pw->pw_gid;
627 if (setgroups(1, gidset) < 0)
628 fatal("setgroups: %.100s", strerror(errno));
629 permanently_set_uid(privsep_pw);
634 privsep_preauth(Authctxt *authctxt)
638 struct ssh_sandbox *box = NULL;
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;
645 if (use_privsep == PRIVSEP_ON)
646 box = ssh_sandbox_init();
649 fatal("fork of unprivileged child failed");
650 } else if (pid != 0) {
651 debug2("Network child is on pid %ld", (long)pid);
653 pmonitor->m_pid = pid;
655 ssh_sandbox_parent_preauth(box, pid);
656 monitor_child_preauth(authctxt, pmonitor);
659 monitor_sync(pmonitor);
661 /* Wait for the child's exit status */
662 while (waitpid(pid, &status, 0) < 0) {
665 pmonitor->m_pid = -1;
666 fatal("%s: waitpid: %s", __func__, strerror(errno));
668 privsep_is_preauth = 0;
669 pmonitor->m_pid = -1;
670 if (WIFEXITED(status)) {
671 if (WEXITSTATUS(status) != 0)
672 fatal("%s: preauth child exited with status %d",
673 __func__, WEXITSTATUS(status));
674 } else if (WIFSIGNALED(status))
675 fatal("%s: preauth child terminated by signal %d",
676 __func__, WTERMSIG(status));
678 ssh_sandbox_parent_finish(box);
682 close(pmonitor->m_sendfd);
683 close(pmonitor->m_log_recvfd);
685 /* Arrange for logging to be sent to the monitor */
686 set_log_handler(mm_log_handler, pmonitor);
688 /* Demote the child */
689 if (getuid() == 0 || geteuid() == 0)
690 privsep_preauth_child();
691 setproctitle("%s", "[net]");
693 ssh_sandbox_child(box);
700 privsep_postauth(Authctxt *authctxt)
704 #ifdef DISABLE_FD_PASSING
707 if (authctxt->pw->pw_uid == 0 || options.use_login) {
709 /* File descriptor passing is broken or root login */
714 /* New socket pair */
715 monitor_reinit(pmonitor);
717 pmonitor->m_pid = fork();
718 if (pmonitor->m_pid == -1)
719 fatal("fork of unprivileged child failed");
720 else if (pmonitor->m_pid != 0) {
721 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
722 buffer_clear(&loginmsg);
723 monitor_child_postauth(pmonitor);
731 close(pmonitor->m_sendfd);
732 pmonitor->m_sendfd = -1;
734 /* Demote the private keys to public keys. */
735 demote_sensitive_data();
738 arc4random_buf(rnd, sizeof(rnd));
739 RAND_seed(rnd, sizeof(rnd));
741 /* Drop privileges */
742 do_setusercontext(authctxt->pw);
745 /* It is safe now to apply the key state */
746 monitor_apply_keystate(pmonitor);
749 * Tell the packet layer that authentication was successful, since
750 * this information is not part of the key state.
752 packet_set_authenticated();
756 list_hostkey_types(void)
765 for (i = 0; i < options.num_host_key_files; i++) {
766 key = sensitive_data.host_keys[i];
773 if (buffer_len(&b) > 0)
774 buffer_append(&b, ",", 1);
775 p = key_ssh_name(key);
776 buffer_append(&b, p, strlen(p));
779 /* If the private key has a cert peer, then list that too */
780 key = sensitive_data.host_certificates[i];
784 case KEY_RSA_CERT_V00:
785 case KEY_DSA_CERT_V00:
789 if (buffer_len(&b) > 0)
790 buffer_append(&b, ",", 1);
791 p = key_ssh_name(key);
792 buffer_append(&b, p, strlen(p));
796 buffer_append(&b, "\0", 1);
797 ret = xstrdup(buffer_ptr(&b));
799 debug("list_hostkey_types: %s", ret);
804 get_hostkey_by_type(int type, int need_private)
809 for (i = 0; i < options.num_host_key_files; i++) {
811 case KEY_RSA_CERT_V00:
812 case KEY_DSA_CERT_V00:
816 key = sensitive_data.host_certificates[i];
819 key = sensitive_data.host_keys[i];
822 if (key != NULL && key->type == type)
823 return need_private ?
824 sensitive_data.host_keys[i] : key;
830 get_hostkey_public_by_type(int type)
832 return get_hostkey_by_type(type, 0);
836 get_hostkey_private_by_type(int type)
838 return get_hostkey_by_type(type, 1);
842 get_hostkey_by_index(int ind)
844 if (ind < 0 || ind >= options.num_host_key_files)
846 return (sensitive_data.host_keys[ind]);
850 get_hostkey_index(Key *key)
854 for (i = 0; i < options.num_host_key_files; i++) {
855 if (key_is_cert(key)) {
856 if (key == sensitive_data.host_certificates[i])
859 if (key == sensitive_data.host_keys[i])
867 * returns 1 if connection should be dropped, 0 otherwise.
868 * dropping starts at connection #max_startups_begin with a probability
869 * of (max_startups_rate/100). the probability increases linearly until
870 * all connections are dropped for startups > max_startups
873 drop_connection(int startups)
877 if (startups < options.max_startups_begin)
879 if (startups >= options.max_startups)
881 if (options.max_startups_rate == 100)
884 p = 100 - options.max_startups_rate;
885 p *= startups - options.max_startups_begin;
886 p /= options.max_startups - options.max_startups_begin;
887 p += options.max_startups_rate;
888 r = arc4random_uniform(100);
890 debug("drop_connection: p %d, r %d", p, r);
891 return (r < p) ? 1 : 0;
897 fprintf(stderr, "%s, %s\n",
898 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
900 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
901 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
902 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
908 send_rexec_state(int fd, Buffer *conf)
912 debug3("%s: entering fd = %d config len %d", __func__, fd,
916 * Protocol from reexec master to child:
917 * string configuration
918 * u_int ephemeral_key_follows
919 * bignum e (only if ephemeral_key_follows == 1)
925 * string rngseed (only if OpenSSL is not self-seeded)
928 buffer_put_cstring(&m, buffer_ptr(conf));
930 if (sensitive_data.server_key != NULL &&
931 sensitive_data.server_key->type == KEY_RSA1) {
932 buffer_put_int(&m, 1);
933 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
934 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
935 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
936 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
937 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
938 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
940 buffer_put_int(&m, 0);
942 #ifndef OPENSSL_PRNG_ONLY
943 rexec_send_rng_seed(&m);
946 if (ssh_msg_send(fd, 0, &m) == -1)
947 fatal("%s: ssh_msg_send failed", __func__);
951 debug3("%s: done", __func__);
955 recv_rexec_state(int fd, Buffer *conf)
961 debug3("%s: entering fd = %d", __func__, fd);
965 if (ssh_msg_recv(fd, &m) == -1)
966 fatal("%s: ssh_msg_recv failed", __func__);
967 if (buffer_get_char(&m) != 0)
968 fatal("%s: rexec version mismatch", __func__);
970 cp = buffer_get_string(&m, &len);
972 buffer_append(conf, cp, len + 1);
975 if (buffer_get_int(&m)) {
976 if (sensitive_data.server_key != NULL)
977 key_free(sensitive_data.server_key);
978 sensitive_data.server_key = key_new_private(KEY_RSA1);
979 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
980 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
981 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
982 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
983 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
984 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
985 rsa_generate_additional_parameters(
986 sensitive_data.server_key->rsa);
989 #ifndef OPENSSL_PRNG_ONLY
990 rexec_recv_rng_seed(&m);
995 debug3("%s: done", __func__);
998 /* Accept a connection from inetd */
1000 server_accept_inetd(int *sock_in, int *sock_out)
1006 close(REEXEC_CONFIG_PASS_FD);
1007 *sock_in = *sock_out = dup(STDIN_FILENO);
1009 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1010 close(REEXEC_STARTUP_PIPE_FD);
1013 *sock_in = dup(STDIN_FILENO);
1014 *sock_out = dup(STDOUT_FILENO);
1017 * We intentionally do not close the descriptors 0, 1, and 2
1018 * as our code for setting the descriptors won't work if
1019 * ttyfd happens to be one of those.
1021 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1022 dup2(fd, STDIN_FILENO);
1023 dup2(fd, STDOUT_FILENO);
1024 if (fd > STDOUT_FILENO)
1027 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1031 * Listen for TCP connections
1036 int ret, listen_sock, on = 1;
1037 struct addrinfo *ai;
1038 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1040 int socksizelen = sizeof(int);
1042 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1043 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1045 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1046 fatal("Too many listen sockets. "
1047 "Enlarge MAX_LISTEN_SOCKS");
1048 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1049 ntop, sizeof(ntop), strport, sizeof(strport),
1050 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1051 error("getnameinfo failed: %.100s",
1052 ssh_gai_strerror(ret));
1055 /* Create socket for listening. */
1056 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1058 if (listen_sock < 0) {
1059 /* kernel may not support ipv6 */
1060 verbose("socket: %.100s", strerror(errno));
1063 if (set_nonblock(listen_sock) == -1) {
1068 * Set socket options.
1069 * Allow local port reuse in TIME_WAIT.
1071 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1072 &on, sizeof(on)) == -1)
1073 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1075 /* Only communicate in IPv6 over AF_INET6 sockets. */
1076 if (ai->ai_family == AF_INET6)
1077 sock_set_v6only(listen_sock);
1079 debug("Bind to port %s on %s.", strport, ntop);
1081 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF,
1082 &socksize, &socksizelen);
1083 debug("Server TCP RWIN socket size: %d", socksize);
1084 debug("HPN Buffer Size: %d", options.hpn_buffer_size);
1086 /* Bind the socket to the desired port. */
1087 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1088 error("Bind to port %s on %s failed: %.200s.",
1089 strport, ntop, strerror(errno));
1093 listen_socks[num_listen_socks] = listen_sock;
1096 /* Start listening on the port. */
1097 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1098 fatal("listen on [%s]:%s: %.100s",
1099 ntop, strport, strerror(errno));
1100 logit("Server listening on %s port %s.", ntop, strport);
1102 freeaddrinfo(options.listen_addrs);
1104 if (!num_listen_socks)
1105 fatal("Cannot bind any address.");
1109 * The main TCP accept loop. Note that, for the non-debug case, returns
1110 * from this function are in a forked subprocess.
1113 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1116 int i, j, ret, maxfd;
1117 int key_used = 0, startups = 0;
1118 int startup_p[2] = { -1 , -1 };
1119 struct sockaddr_storage from;
1123 /* setup fd set for accept */
1126 for (i = 0; i < num_listen_socks; i++)
1127 if (listen_socks[i] > maxfd)
1128 maxfd = listen_socks[i];
1129 /* pipes connected to unauthenticated childs */
1130 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1131 for (i = 0; i < options.max_startups; i++)
1132 startup_pipes[i] = -1;
1135 * Stay listening for connections until the system crashes or
1136 * the daemon is killed with a signal.
1139 if (received_sighup)
1143 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1146 for (i = 0; i < num_listen_socks; i++)
1147 FD_SET(listen_socks[i], fdset);
1148 for (i = 0; i < options.max_startups; i++)
1149 if (startup_pipes[i] != -1)
1150 FD_SET(startup_pipes[i], fdset);
1152 /* Wait in select until there is a connection. */
1153 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1154 if (ret < 0 && errno != EINTR)
1155 error("select: %.100s", strerror(errno));
1156 if (received_sigterm) {
1157 logit("Received signal %d; terminating.",
1158 (int) received_sigterm);
1159 close_listen_socks();
1160 unlink(options.pid_file);
1161 exit(received_sigterm == SIGTERM ? 0 : 255);
1163 if (key_used && key_do_regen) {
1164 generate_ephemeral_server_key();
1171 for (i = 0; i < options.max_startups; i++)
1172 if (startup_pipes[i] != -1 &&
1173 FD_ISSET(startup_pipes[i], fdset)) {
1175 * the read end of the pipe is ready
1176 * if the child has closed the pipe
1177 * after successful authentication
1178 * or if the child has died
1180 close(startup_pipes[i]);
1181 startup_pipes[i] = -1;
1184 for (i = 0; i < num_listen_socks; i++) {
1185 if (!FD_ISSET(listen_socks[i], fdset))
1187 fromlen = sizeof(from);
1188 *newsock = accept(listen_socks[i],
1189 (struct sockaddr *)&from, &fromlen);
1191 if (errno != EINTR && errno != EAGAIN &&
1192 errno != EWOULDBLOCK)
1193 error("accept: %.100s",
1195 if (errno == EMFILE || errno == ENFILE)
1199 if (unset_nonblock(*newsock) == -1) {
1203 if (drop_connection(startups) == 1) {
1204 debug("drop connection #%d", startups);
1208 if (pipe(startup_p) == -1) {
1213 if (rexec_flag && socketpair(AF_UNIX,
1214 SOCK_STREAM, 0, config_s) == -1) {
1215 error("reexec socketpair: %s",
1218 close(startup_p[0]);
1219 close(startup_p[1]);
1223 for (j = 0; j < options.max_startups; j++)
1224 if (startup_pipes[j] == -1) {
1225 startup_pipes[j] = startup_p[0];
1226 if (maxfd < startup_p[0])
1227 maxfd = startup_p[0];
1233 * Got connection. Fork a child to handle it, unless
1234 * we are in debugging mode.
1238 * In debugging mode. Close the listening
1239 * socket, and start processing the
1240 * connection without forking.
1242 debug("Server will not fork when running in debugging mode.");
1243 close_listen_socks();
1244 *sock_in = *newsock;
1245 *sock_out = *newsock;
1246 close(startup_p[0]);
1247 close(startup_p[1]);
1251 send_rexec_state(config_s[0],
1259 * Normal production daemon. Fork, and have
1260 * the child process the connection. The
1261 * parent continues listening.
1263 platform_pre_fork();
1264 if ((pid = fork()) == 0) {
1266 * Child. Close the listening and
1267 * max_startup sockets. Start using
1268 * the accepted socket. Reinitialize
1269 * logging (since our pid has changed).
1270 * We break out of the loop to handle
1273 platform_post_fork_child();
1274 startup_pipe = startup_p[1];
1275 close_startup_pipes();
1276 close_listen_socks();
1277 *sock_in = *newsock;
1278 *sock_out = *newsock;
1279 log_init(__progname,
1281 options.log_facility,
1288 /* Parent. Stay in the loop. */
1289 platform_post_fork_parent(pid);
1291 error("fork: %.100s", strerror(errno));
1293 debug("Forked child %ld.", (long)pid);
1295 close(startup_p[1]);
1298 send_rexec_state(config_s[0], &cfg);
1304 * Mark that the key has been used (it
1305 * was "given" to the child).
1307 if ((options.protocol & SSH_PROTO_1) &&
1309 /* Schedule server key regeneration alarm. */
1310 signal(SIGALRM, key_regeneration_alarm);
1311 alarm(options.key_regeneration_time);
1318 * Ensure that our random state differs
1319 * from that of the child
1324 /* child process check (or debug mode) */
1325 if (num_listen_socks < 0)
1332 * Main program for the daemon.
1335 main(int ac, char **av)
1337 extern char *optarg;
1339 int opt, i, j, on = 1;
1340 int sock_in = -1, sock_out = -1, newsock = -1;
1341 const char *remote_ip;
1344 int config_s[2] = { -1 , -1 };
1345 u_int64_t ibytes, obytes;
1349 struct connection_info *connection_info = get_connection_info(0, 0);
1351 #ifdef HAVE_SECUREWARE
1352 (void)set_auth_parameters(ac, av);
1354 __progname = ssh_get_progname(av[0]);
1356 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1359 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1360 for (i = 0; i < ac; i++)
1361 saved_argv[i] = xstrdup(av[i]);
1362 saved_argv[i] = NULL;
1364 #ifndef HAVE_SETPROCTITLE
1365 /* Prepare for later setproctitle emulation */
1366 compat_init_setproctitle(ac, av);
1370 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1371 debug("setgroups(): %.200s", strerror(errno));
1373 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1376 /* Initialize configuration options to their default values. */
1377 initialize_server_options(&options);
1379 /* Parse command-line arguments. */
1380 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1383 options.address_family = AF_INET;
1386 options.address_family = AF_INET6;
1389 config_file_name = optarg;
1392 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1393 fprintf(stderr, "too many host certificates.\n");
1396 options.host_cert_files[options.num_host_cert_files++] =
1397 derelativise_path(optarg);
1400 if (debug_flag == 0) {
1402 options.log_level = SYSLOG_LEVEL_DEBUG1;
1403 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1404 options.log_level++;
1426 options.log_level = SYSLOG_LEVEL_QUIET;
1429 options.server_key_bits = (int)strtonum(optarg, 256,
1433 options.ports_from_cmdline = 1;
1434 if (options.num_ports >= MAX_PORTS) {
1435 fprintf(stderr, "too many ports.\n");
1438 options.ports[options.num_ports++] = a2port(optarg);
1439 if (options.ports[options.num_ports-1] <= 0) {
1440 fprintf(stderr, "Bad port number.\n");
1445 if ((options.login_grace_time = convtime(optarg)) == -1) {
1446 fprintf(stderr, "Invalid login grace time.\n");
1451 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1452 fprintf(stderr, "Invalid key regeneration interval.\n");
1457 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1458 fprintf(stderr, "too many host keys.\n");
1461 options.host_key_files[options.num_host_key_files++] =
1462 derelativise_path(optarg);
1471 if (parse_server_match_testspec(connection_info,
1476 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1477 if (utmp_len > MAXHOSTNAMELEN) {
1478 fprintf(stderr, "Invalid utmp length.\n");
1483 line = xstrdup(optarg);
1484 if (process_server_config_line(&options, line,
1485 "command-line", 0, NULL, NULL) != 0)
1495 if (rexeced_flag || inetd_flag)
1497 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1498 fatal("sshd re-exec requires execution with an absolute path");
1500 closefrom(REEXEC_MIN_FREE_FD);
1502 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1504 OpenSSL_add_all_algorithms();
1507 * Force logging to stderr until we have loaded the private host
1508 * key (unless started from inetd)
1510 log_init(__progname,
1511 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1512 SYSLOG_LEVEL_INFO : options.log_level,
1513 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1514 SYSLOG_FACILITY_AUTH : options.log_facility,
1515 log_stderr || !inetd_flag);
1518 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1519 * root's environment
1521 if (getenv("KRB5CCNAME") != NULL)
1522 (void) unsetenv("KRB5CCNAME");
1525 /* Cray can define user privs drop all privs now!
1526 * Not needed on PRIV_SU systems!
1531 sensitive_data.server_key = NULL;
1532 sensitive_data.ssh1_host_key = NULL;
1533 sensitive_data.have_ssh1_key = 0;
1534 sensitive_data.have_ssh2_key = 0;
1537 * If we're doing an extended config test, make sure we have all of
1538 * the parameters we need. If we're not doing an extended test,
1539 * do not silently ignore connection test params.
1541 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0)
1542 fatal("user, host and addr are all required when testing "
1544 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0)
1545 fatal("Config test connection parameter (-C) provided without "
1548 /* Fetch our configuration */
1551 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1553 load_server_config(config_file_name, &cfg);
1555 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1560 /* Fill in default values for those options not explicitly set. */
1561 fill_default_server_options(&options);
1563 /* challenge-response is implemented via keyboard interactive */
1564 if (options.challenge_response_authentication)
1565 options.kbd_interactive_authentication = 1;
1567 /* set default channel AF */
1568 channel_set_af(options.address_family);
1570 /* Check that there are no remaining arguments. */
1572 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1576 debug("sshd version %.100s", SSH_RELEASE);
1578 /* Store privilege separation user for later use if required. */
1579 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1580 if (use_privsep || options.kerberos_authentication)
1581 fatal("Privilege separation user %s does not exist",
1584 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1585 privsep_pw = pwcopy(privsep_pw);
1586 xfree(privsep_pw->pw_passwd);
1587 privsep_pw->pw_passwd = xstrdup("*");
1591 /* load private host keys */
1592 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1594 for (i = 0; i < options.num_host_key_files; i++)
1595 sensitive_data.host_keys[i] = NULL;
1597 for (i = 0; i < options.num_host_key_files; i++) {
1598 key = key_load_private(options.host_key_files[i], "", NULL);
1599 if (key && blacklisted_key(key)) {
1601 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
1602 if (options.permit_blacklisted_keys)
1603 error("Host key %s blacklisted (see "
1604 "ssh-vulnkey(1)); continuing anyway", fp);
1606 error("Host key %s blacklisted (see "
1607 "ssh-vulnkey(1))", fp);
1609 if (!options.permit_blacklisted_keys) {
1610 sensitive_data.host_keys[i] = NULL;
1614 sensitive_data.host_keys[i] = key;
1616 error("Could not load host key: %s",
1617 options.host_key_files[i]);
1618 sensitive_data.host_keys[i] = NULL;
1621 switch (key->type) {
1623 sensitive_data.ssh1_host_key = key;
1624 sensitive_data.have_ssh1_key = 1;
1629 sensitive_data.have_ssh2_key = 1;
1632 debug("private host key: #%d type %d %s", i, key->type,
1635 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1636 logit("Disabling protocol version 1. Could not load host key");
1637 options.protocol &= ~SSH_PROTO_1;
1639 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1640 logit("Disabling protocol version 2. Could not load host key");
1641 options.protocol &= ~SSH_PROTO_2;
1643 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1644 logit("sshd: no hostkeys available -- exiting.");
1649 * Load certificates. They are stored in an array at identical
1650 * indices to the public keys that they relate to.
1652 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1654 for (i = 0; i < options.num_host_key_files; i++)
1655 sensitive_data.host_certificates[i] = NULL;
1657 for (i = 0; i < options.num_host_cert_files; i++) {
1658 key = key_load_public(options.host_cert_files[i], NULL);
1660 error("Could not load host certificate: %s",
1661 options.host_cert_files[i]);
1664 if (!key_is_cert(key)) {
1665 error("Certificate file is not a certificate: %s",
1666 options.host_cert_files[i]);
1670 /* Find matching private key */
1671 for (j = 0; j < options.num_host_key_files; j++) {
1672 if (key_equal_public(key,
1673 sensitive_data.host_keys[j])) {
1674 sensitive_data.host_certificates[j] = key;
1678 if (j >= options.num_host_key_files) {
1679 error("No matching private key for certificate: %s",
1680 options.host_cert_files[i]);
1684 sensitive_data.host_certificates[j] = key;
1685 debug("host certificate: #%d type %d %s", j, key->type,
1688 /* Check certain values for sanity. */
1689 if (options.protocol & SSH_PROTO_1) {
1690 if (options.server_key_bits < 512 ||
1691 options.server_key_bits > 32768) {
1692 fprintf(stderr, "Bad server key size.\n");
1696 * Check that server and host key lengths differ sufficiently. This
1697 * is necessary to make double encryption work with rsaref. Oh, I
1698 * hate software patents. I dont know if this can go? Niels
1700 if (options.server_key_bits >
1701 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1702 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1703 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1704 SSH_KEY_BITS_RESERVED) {
1705 options.server_key_bits =
1706 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1707 SSH_KEY_BITS_RESERVED;
1708 debug("Forcing server key to %d bits to make it differ from host key.",
1709 options.server_key_bits);
1716 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1717 (S_ISDIR(st.st_mode) == 0))
1718 fatal("Missing privilege separation directory: %s",
1719 _PATH_PRIVSEP_CHROOT_DIR);
1722 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1723 (st.st_uid != getuid () ||
1724 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1726 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1728 fatal("%s must be owned by root and not group or "
1729 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1732 if (test_flag > 1) {
1733 if (server_match_spec_complete(connection_info) == 1)
1734 parse_server_match_config(&options, connection_info);
1735 dump_config(&options);
1738 /* Configuration looks good, so exit if in test mode. */
1743 * Clear out any supplemental groups we may have inherited. This
1744 * prevents inadvertent creation of files with bad modes (in the
1745 * portable version at least, it's certainly possible for PAM
1746 * to create a file, and we can't control the code in every
1747 * module which might be used).
1749 if (setgroups(0, NULL) < 0)
1750 debug("setgroups() failed: %.200s", strerror(errno));
1753 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1754 for (i = 0; i < rexec_argc; i++) {
1755 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1756 rexec_argv[i] = saved_argv[i];
1758 rexec_argv[rexec_argc] = "-R";
1759 rexec_argv[rexec_argc + 1] = NULL;
1762 /* Ensure that umask disallows at least group and world write */
1763 new_umask = umask(0077) | 0022;
1764 (void) umask(new_umask);
1766 /* Initialize the log (it is reinitialized below in case we forked). */
1767 if (debug_flag && (!inetd_flag || rexeced_flag))
1769 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1772 * If not in debugging mode, and not started from inetd, disconnect
1773 * from the controlling terminal, and fork. The original process
1776 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1779 #endif /* TIOCNOTTY */
1780 if (daemon(0, 0) < 0)
1781 fatal("daemon() failed: %.200s", strerror(errno));
1783 /* Disconnect from the controlling tty. */
1785 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1787 (void) ioctl(fd, TIOCNOTTY, NULL);
1790 #endif /* TIOCNOTTY */
1792 /* Reinitialize the log (because of the fork above). */
1793 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1795 /* Initialize the random number generator. */
1798 /* Chdir to the root directory so that the current disk can be
1799 unmounted if desired. */
1802 /* ignore SIGPIPE */
1803 signal(SIGPIPE, SIG_IGN);
1805 /* Get a connection, either from inetd or a listening TCP socket */
1807 server_accept_inetd(&sock_in, &sock_out);
1809 platform_pre_listen();
1812 if (options.protocol & SSH_PROTO_1)
1813 generate_ephemeral_server_key();
1815 signal(SIGHUP, sighup_handler);
1816 signal(SIGCHLD, main_sigchld_handler);
1817 signal(SIGTERM, sigterm_handler);
1818 signal(SIGQUIT, sigterm_handler);
1821 * Write out the pid file after the sigterm handler
1822 * is setup and the listen sockets are bound
1825 FILE *f = fopen(options.pid_file, "w");
1828 error("Couldn't create pid file \"%s\": %s",
1829 options.pid_file, strerror(errno));
1831 fprintf(f, "%ld\n", (long) getpid());
1836 /* Accept a connection and return in a forked child */
1837 server_accept_loop(&sock_in, &sock_out,
1838 &newsock, config_s);
1841 /* This is the child processing a new connection. */
1842 setproctitle("%s", "[accepted]");
1845 * Initialize the resolver. This may not happen automatically
1846 * before privsep chroot().
1848 if ((_res.options & RES_INIT) == 0) {
1849 debug("res_init()");
1854 * Create a new session and process group since the 4.4BSD
1855 * setlogin() affects the entire process group. We don't
1856 * want the child to be able to affect the parent.
1858 #if !defined(SSHD_ACQUIRES_CTTY)
1860 * If setsid is called, on some platforms sshd will later acquire a
1861 * controlling terminal which will result in "could not set
1862 * controlling tty" errors.
1864 if (!debug_flag && !inetd_flag && setsid() < 0)
1865 error("setsid: %.100s", strerror(errno));
1871 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1872 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1873 dup2(newsock, STDIN_FILENO);
1874 dup2(STDIN_FILENO, STDOUT_FILENO);
1875 if (startup_pipe == -1)
1876 close(REEXEC_STARTUP_PIPE_FD);
1878 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1880 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1882 if (startup_pipe != -1)
1883 close(startup_pipe);
1885 execv(rexec_argv[0], rexec_argv);
1887 /* Reexec has failed, fall back and continue */
1888 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1889 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1890 log_init(__progname, options.log_level,
1891 options.log_facility, log_stderr);
1894 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1896 close(REEXEC_CONFIG_PASS_FD);
1897 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1898 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1899 dup2(fd, STDIN_FILENO);
1900 dup2(fd, STDOUT_FILENO);
1901 if (fd > STDERR_FILENO)
1904 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1905 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1908 /* Executed child processes don't need these. */
1909 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1910 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1913 * Disable the key regeneration alarm. We will not regenerate the
1914 * key since we are no longer in a position to give it to anyone. We
1915 * will not restart on SIGHUP since it no longer makes sense.
1918 signal(SIGALRM, SIG_DFL);
1919 signal(SIGHUP, SIG_DFL);
1920 signal(SIGTERM, SIG_DFL);
1921 signal(SIGQUIT, SIG_DFL);
1922 signal(SIGCHLD, SIG_DFL);
1923 signal(SIGINT, SIG_DFL);
1926 * Register our connection. This turns encryption off because we do
1929 packet_set_connection(sock_in, sock_out);
1930 packet_set_server();
1932 /* Set SO_KEEPALIVE if requested. */
1933 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1934 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1935 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1937 if ((remote_port = get_remote_port()) < 0) {
1938 debug("get_remote_port failed");
1943 * We use get_canonical_hostname with usedns = 0 instead of
1944 * get_remote_ipaddr here so IP options will be checked.
1946 (void) get_canonical_hostname(0);
1948 * The rest of the code depends on the fact that
1949 * get_remote_ipaddr() caches the remote ip, even if
1950 * the socket goes away.
1952 remote_ip = get_remote_ipaddr();
1954 #ifdef SSH_AUDIT_EVENTS
1955 audit_connection_from(remote_ip, remote_port);
1958 allow_severity = options.log_facility|LOG_INFO;
1959 deny_severity = options.log_facility|LOG_WARNING;
1960 /* Check whether logins are denied from this host. */
1961 if (packet_connection_is_on_socket()) {
1962 struct request_info req;
1964 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1967 if (!hosts_access(&req)) {
1968 debug("Connection refused by tcp wrapper");
1971 fatal("libwrap refuse returns");
1974 #endif /* LIBWRAP */
1976 /* Log the connection. */
1977 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1979 /* set the HPN options for the child */
1980 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1983 * We don't want to listen forever unless the other side
1984 * successfully authenticates itself. So we set up an alarm which is
1985 * cleared after successful authentication. A limit of zero
1986 * indicates no limit. Note that we don't set the alarm in debugging
1987 * mode; it is just annoying to have the server exit just when you
1988 * are about to discover the bug.
1990 signal(SIGALRM, grace_alarm_handler);
1992 alarm(options.login_grace_time);
1994 sshd_exchange_identification(sock_in, sock_out);
1996 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1997 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1998 generate_ephemeral_server_key();
2000 packet_set_nonblocking();
2002 /* allocate authentication context */
2003 authctxt = xcalloc(1, sizeof(*authctxt));
2005 authctxt->loginmsg = &loginmsg;
2007 /* XXX global for cleanup, access from other modules */
2008 the_authctxt = authctxt;
2010 /* prepare buffer to collect messages to display to user after login */
2011 buffer_init(&loginmsg);
2015 if (privsep_preauth(authctxt) == 1)
2018 /* perform the key exchange */
2019 /* authenticate user and start session */
2022 do_authentication2(authctxt);
2025 do_authentication(authctxt);
2028 * If we use privilege separation, the unprivileged child transfers
2029 * the current keystate and exits
2032 mm_send_keystate(pmonitor);
2038 * Cancel the alarm we set to limit the time taken for
2042 signal(SIGALRM, SIG_DFL);
2043 authctxt->authenticated = 1;
2044 if (startup_pipe != -1) {
2045 close(startup_pipe);
2049 #ifdef SSH_AUDIT_EVENTS
2050 audit_event(SSH_AUTH_SUCCESS);
2054 if (options.gss_authentication) {
2055 temporarily_use_uid(authctxt->pw);
2056 ssh_gssapi_storecreds();
2061 if (options.use_pam) {
2068 * In privilege separation, we fork another child and prepare
2069 * file descriptor passing.
2072 privsep_postauth(authctxt);
2073 /* the monitor process [priv] will not return */
2075 destroy_sensitive_data();
2078 packet_set_timeout(options.client_alive_interval,
2079 options.client_alive_count_max);
2081 /* Start session. */
2082 do_authenticated(authctxt);
2084 /* The connection has been terminated. */
2085 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2086 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2087 verbose("Transferred: sent %llu, received %llu bytes",
2088 (unsigned long long)obytes, (unsigned long long)ibytes);
2090 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2093 if (options.use_pam)
2095 #endif /* USE_PAM */
2097 #ifdef SSH_AUDIT_EVENTS
2098 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2110 * Decrypt session_key_int using our private server key and private host key
2111 * (key with larger modulus first).
2114 ssh1_session_key(BIGNUM *session_key_int)
2118 if (BN_cmp(sensitive_data.server_key->rsa->n,
2119 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2120 /* Server key has bigger modulus. */
2121 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2122 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2123 SSH_KEY_BITS_RESERVED) {
2124 fatal("do_connection: %s: "
2125 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2126 get_remote_ipaddr(),
2127 BN_num_bits(sensitive_data.server_key->rsa->n),
2128 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2129 SSH_KEY_BITS_RESERVED);
2131 if (rsa_private_decrypt(session_key_int, session_key_int,
2132 sensitive_data.server_key->rsa) <= 0)
2134 if (rsa_private_decrypt(session_key_int, session_key_int,
2135 sensitive_data.ssh1_host_key->rsa) <= 0)
2138 /* Host key has bigger modulus (or they are equal). */
2139 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2140 BN_num_bits(sensitive_data.server_key->rsa->n) +
2141 SSH_KEY_BITS_RESERVED) {
2142 fatal("do_connection: %s: "
2143 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2144 get_remote_ipaddr(),
2145 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2146 BN_num_bits(sensitive_data.server_key->rsa->n),
2147 SSH_KEY_BITS_RESERVED);
2149 if (rsa_private_decrypt(session_key_int, session_key_int,
2150 sensitive_data.ssh1_host_key->rsa) < 0)
2152 if (rsa_private_decrypt(session_key_int, session_key_int,
2153 sensitive_data.server_key->rsa) < 0)
2166 BIGNUM *session_key_int;
2167 u_char session_key[SSH_SESSION_KEY_LENGTH];
2169 u_int cipher_type, auth_mask, protocol_flags;
2172 * Generate check bytes that the client must send back in the user
2173 * packet in order for it to be accepted; this is used to defy ip
2174 * spoofing attacks. Note that this only works against somebody
2175 * doing IP spoofing from a remote machine; any machine on the local
2176 * network can still see outgoing packets and catch the random
2177 * cookie. This only affects rhosts authentication, and this is one
2178 * of the reasons why it is inherently insecure.
2180 arc4random_buf(cookie, sizeof(cookie));
2183 * Send our public key. We include in the packet 64 bits of random
2184 * data that must be matched in the reply in order to prevent IP
2187 packet_start(SSH_SMSG_PUBLIC_KEY);
2188 for (i = 0; i < 8; i++)
2189 packet_put_char(cookie[i]);
2191 /* Store our public server RSA key. */
2192 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2193 packet_put_bignum(sensitive_data.server_key->rsa->e);
2194 packet_put_bignum(sensitive_data.server_key->rsa->n);
2196 /* Store our public host RSA key. */
2197 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2198 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2199 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2201 /* Put protocol flags. */
2202 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2204 /* Declare which ciphers we support. */
2205 packet_put_int(cipher_mask_ssh1(0));
2207 /* Declare supported authentication types. */
2209 if (options.rhosts_rsa_authentication)
2210 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2211 if (options.rsa_authentication)
2212 auth_mask |= 1 << SSH_AUTH_RSA;
2213 if (options.challenge_response_authentication == 1)
2214 auth_mask |= 1 << SSH_AUTH_TIS;
2215 if (options.password_authentication)
2216 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2217 packet_put_int(auth_mask);
2219 /* Send the packet and wait for it to be sent. */
2221 packet_write_wait();
2223 debug("Sent %d bit server key and %d bit host key.",
2224 BN_num_bits(sensitive_data.server_key->rsa->n),
2225 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2227 /* Read clients reply (cipher type and session key). */
2228 packet_read_expect(SSH_CMSG_SESSION_KEY);
2230 /* Get cipher type and check whether we accept this. */
2231 cipher_type = packet_get_char();
2233 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2234 packet_disconnect("Warning: client selects unsupported cipher.");
2236 /* Get check bytes from the packet. These must match those we
2237 sent earlier with the public key packet. */
2238 for (i = 0; i < 8; i++)
2239 if (cookie[i] != packet_get_char())
2240 packet_disconnect("IP Spoofing check bytes do not match.");
2242 debug("Encryption type: %.200s", cipher_name(cipher_type));
2244 /* Get the encrypted integer. */
2245 if ((session_key_int = BN_new()) == NULL)
2246 fatal("do_ssh1_kex: BN_new failed");
2247 packet_get_bignum(session_key_int);
2249 protocol_flags = packet_get_int();
2250 packet_set_protocol_flags(protocol_flags);
2253 /* Decrypt session_key_int using host/server keys */
2254 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2257 * Extract session key from the decrypted integer. The key is in the
2258 * least significant 256 bits of the integer; the first byte of the
2259 * key is in the highest bits.
2262 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2263 len = BN_num_bytes(session_key_int);
2264 if (len < 0 || (u_int)len > sizeof(session_key)) {
2265 error("do_ssh1_kex: bad session key len from %s: "
2266 "session_key_int %d > sizeof(session_key) %lu",
2267 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2270 memset(session_key, 0, sizeof(session_key));
2271 BN_bn2bin(session_key_int,
2272 session_key + sizeof(session_key) - len);
2274 derive_ssh1_session_id(
2275 sensitive_data.ssh1_host_key->rsa->n,
2276 sensitive_data.server_key->rsa->n,
2277 cookie, session_id);
2279 * Xor the first 16 bytes of the session key with the
2282 for (i = 0; i < 16; i++)
2283 session_key[i] ^= session_id[i];
2287 int bytes = BN_num_bytes(session_key_int);
2288 u_char *buf = xmalloc(bytes);
2291 logit("do_connection: generating a fake encryption key");
2292 BN_bn2bin(session_key_int, buf);
2294 MD5_Update(&md, buf, bytes);
2295 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2296 MD5_Final(session_key, &md);
2298 MD5_Update(&md, session_key, 16);
2299 MD5_Update(&md, buf, bytes);
2300 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2301 MD5_Final(session_key + 16, &md);
2302 memset(buf, 0, bytes);
2304 for (i = 0; i < 16; i++)
2305 session_id[i] = session_key[i] ^ session_key[i + 16];
2307 /* Destroy the private and public keys. No longer. */
2308 destroy_sensitive_data();
2311 mm_ssh1_session_id(session_id);
2313 /* Destroy the decrypted integer. It is no longer needed. */
2314 BN_clear_free(session_key_int);
2316 /* Set the session key. From this on all communications will be encrypted. */
2317 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2319 /* Destroy our copy of the session key. It is no longer needed. */
2320 memset(session_key, 0, sizeof(session_key));
2322 debug("Received session key; encryption turned on.");
2324 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2325 packet_start(SSH_SMSG_SUCCESS);
2327 packet_write_wait();
2331 * SSH2 key exchange: diffie-hellman-group1-sha1
2339 debug ("MYFLAG IS %d", myflag);
2340 if (options.ciphers != NULL) {
2341 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2342 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2343 } else if (options.none_enabled == 1) {
2344 debug ("WARNING: None cipher enabled");
2345 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2346 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE;
2348 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2349 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2350 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2351 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2353 if (options.macs != NULL) {
2354 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2355 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2357 if (options.compression == COMP_NONE) {
2358 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2359 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2360 } else if (options.compression == COMP_DELAYED) {
2361 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2362 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2364 if (options.kex_algorithms != NULL)
2365 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
2367 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2369 /* start key exchange */
2370 kex = kex_setup(myproposal);
2371 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2372 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2373 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2374 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2375 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2377 kex->client_version_string=client_version_string;
2378 kex->server_version_string=server_version_string;
2379 kex->load_host_public_key=&get_hostkey_public_by_type;
2380 kex->load_host_private_key=&get_hostkey_private_by_type;
2381 kex->host_key_index=&get_hostkey_index;
2385 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2387 session_id2 = kex->session_id;
2388 session_id2_len = kex->session_id_len;
2391 /* send 1st encrypted/maced/compressed message */
2392 packet_start(SSH2_MSG_IGNORE);
2393 packet_put_cstring("markus");
2395 packet_write_wait();
2400 /* server specific fatal cleanup */
2405 do_cleanup(the_authctxt);
2406 if (use_privsep && privsep_is_preauth && pmonitor->m_pid > 1) {
2407 debug("Killing privsep child %d", pmonitor->m_pid);
2408 if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2410 error("%s: kill(%d): %s", __func__,
2411 pmonitor->m_pid, strerror(errno));
2414 #ifdef SSH_AUDIT_EVENTS
2415 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2416 if (!use_privsep || mm_is_monitor())
2417 audit_event(SSH_CONNECTION_ABANDON);