1 /* $OpenBSD: sshd.c,v 1.470 2016/05/24 04:43:45 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"
79 #include <openssl/dh.h>
80 #include <openssl/bn.h>
81 #include <openssl/rand.h>
82 #include "openbsd-compat/openssl-compat.h"
85 #ifdef HAVE_SECUREWARE
86 #include <sys/security.h>
92 #if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H)
93 #include <gssapi/gssapi.h>
94 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_H)
110 #include "servconf.h"
117 #include "myproposal.h"
118 #include "authfile.h"
119 #include "pathnames.h"
120 #include "atomicio.h"
121 #include "canohost.h"
122 #include "hostfile.h"
126 #include "dispatch.h"
127 #include "channels.h"
129 #include "monitor_mm.h"
134 #include "monitor_wrap.h"
135 #include "ssh-sandbox.h"
151 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
152 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
153 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
154 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
156 extern char *__progname;
158 /* Server configuration options. */
159 ServerOptions options;
161 /* Name of the server configuration file. */
162 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
165 * Debug mode flag. This can be set on the command line. If debug
166 * mode is enabled, extra debugging output will be sent to the system
167 * log, the daemon will not go to background, and will exit after processing
168 * the first connection.
172 /* Flag indicating that the daemon should only test the configuration and keys. */
175 /* Flag indicating that the daemon is being started from inetd. */
178 /* Flag indicating that sshd should not detach and become a daemon. */
179 int no_daemon_flag = 0;
181 /* debug goes to stderr unless inetd_flag is set */
184 /* Saved arguments to main(). */
189 int rexeced_flag = 0;
195 * The sockets that the server is listening; this is used in the SIGHUP
198 #define MAX_LISTEN_SOCKS 16
199 int listen_socks[MAX_LISTEN_SOCKS];
200 int num_listen_socks = 0;
203 * the client's version string, passed by sshd2 in compat mode. if != NULL,
204 * sshd will skip the version-number exchange
206 char *client_version_string = NULL;
207 char *server_version_string = NULL;
209 /* Daemon's agent connection */
214 * Any really sensitive data in the application is contained in this
215 * structure. The idea is that this structure could be locked into memory so
216 * that the pages do not get written into swap. However, there are some
217 * problems. The private key contains BIGNUMs, and we do not (in principle)
218 * have access to the internals of them, and locking just the structure is
219 * not very useful. Currently, memory locking is not implemented.
222 Key *server_key; /* ephemeral server key */
223 Key *ssh1_host_key; /* ssh1 host key */
224 Key **host_keys; /* all private host keys */
225 Key **host_pubkeys; /* all public host keys */
226 Key **host_certificates; /* all public host certificates */
229 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
233 * Flag indicating whether the RSA server key needs to be regenerated.
234 * Is set in the SIGALRM handler and cleared when the key is regenerated.
236 static volatile sig_atomic_t key_do_regen = 0;
238 /* This is set to true when a signal is received. */
239 static volatile sig_atomic_t received_sighup = 0;
240 static volatile sig_atomic_t received_sigterm = 0;
242 /* session identifier, used by RSA-auth */
243 u_char session_id[16];
246 u_char *session_id2 = NULL;
247 u_int session_id2_len = 0;
249 /* record remote hostname or ip */
250 u_int utmp_len = HOST_NAME_MAX+1;
252 /* options.max_startup sized array of fd ints */
253 int *startup_pipes = NULL;
254 int startup_pipe; /* in child */
256 /* variables used for privilege separation */
257 int use_privsep = -1;
258 struct monitor *pmonitor = NULL;
259 int privsep_is_preauth = 1;
261 /* global authentication context */
262 Authctxt *the_authctxt = NULL;
264 /* sshd_config buffer */
267 /* message to be displayed after login */
270 /* Unprivileged user */
271 struct passwd *privsep_pw = NULL;
273 /* Prototypes for various functions defined later in this file. */
274 void destroy_sensitive_data(void);
275 void demote_sensitive_data(void);
278 static void do_ssh1_kex(void);
280 static void do_ssh2_kex(void);
283 * Close all listening sockets
286 close_listen_socks(void)
290 for (i = 0; i < num_listen_socks; i++)
291 close(listen_socks[i]);
292 num_listen_socks = -1;
296 close_startup_pipes(void)
301 for (i = 0; i < options.max_startups; i++)
302 if (startup_pipes[i] != -1)
303 close(startup_pipes[i]);
307 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
308 * the effect is to reread the configuration file (and to regenerate
314 sighup_handler(int sig)
316 int save_errno = errno;
319 signal(SIGHUP, sighup_handler);
324 * Called from the main program after receiving SIGHUP.
325 * Restarts the server.
330 logit("Received SIGHUP; restarting.");
331 platform_pre_restart();
332 close_listen_socks();
333 close_startup_pipes();
334 alarm(0); /* alarm timer persists across exec */
335 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
336 execv(saved_argv[0], saved_argv);
337 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
343 * Generic signal handler for terminating signals in the master daemon.
347 sigterm_handler(int sig)
349 received_sigterm = sig;
353 * SIGCHLD handler. This is called whenever a child dies. This will then
354 * reap any zombies left by exited children.
358 main_sigchld_handler(int sig)
360 int save_errno = errno;
364 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
365 (pid < 0 && errno == EINTR))
368 signal(SIGCHLD, main_sigchld_handler);
373 * Signal handler for the alarm after the login grace period has expired.
377 grace_alarm_handler(int sig)
379 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
380 kill(pmonitor->m_pid, SIGALRM);
383 * Try to kill any processes that we have spawned, E.g. authorized
384 * keys command helpers.
386 if (getpgid(0) == getpid()) {
387 signal(SIGTERM, SIG_IGN);
391 /* Log error and exit. */
392 sigdie("Timeout before authentication for %s port %d",
393 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state));
397 * Signal handler for the key regeneration alarm. Note that this
398 * alarm only occurs in the daemon waiting for connections, and it does not
399 * do anything with the private key or random state before forking.
400 * Thus there should be no concurrency control/asynchronous execution
404 generate_ephemeral_server_key(void)
406 verbose("Generating %s%d bit RSA key.",
407 sensitive_data.server_key ? "new " : "", options.server_key_bits);
408 if (sensitive_data.server_key != NULL)
409 key_free(sensitive_data.server_key);
410 sensitive_data.server_key = key_generate(KEY_RSA1,
411 options.server_key_bits);
412 verbose("RSA key generation complete.");
414 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
419 key_regeneration_alarm(int sig)
421 int save_errno = errno;
423 signal(SIGALRM, SIG_DFL);
429 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out)
433 int remote_major, remote_minor;
435 char *s, *newline = "\n";
436 char buf[256]; /* Must not be larger than remote_version. */
437 char remote_version[256]; /* Must be at least as big as buf. */
439 if ((options.protocol & SSH_PROTO_1) &&
440 (options.protocol & SSH_PROTO_2)) {
441 major = PROTOCOL_MAJOR_1;
443 } else if (options.protocol & SSH_PROTO_2) {
444 major = PROTOCOL_MAJOR_2;
445 minor = PROTOCOL_MINOR_2;
448 major = PROTOCOL_MAJOR_1;
449 minor = PROTOCOL_MINOR_1;
452 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s",
453 major, minor, SSH_VERSION,
454 *options.version_addendum == '\0' ? "" : " ",
455 options.version_addendum, newline);
457 /* Send our protocol version identification. */
458 if (atomicio(vwrite, sock_out, server_version_string,
459 strlen(server_version_string))
460 != strlen(server_version_string)) {
461 logit("Could not write ident string to %s port %d",
462 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
466 /* Read other sides version identification. */
467 memset(buf, 0, sizeof(buf));
468 for (i = 0; i < sizeof(buf) - 1; i++) {
469 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
470 logit("Did not receive identification string "
472 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
475 if (buf[i] == '\r') {
477 /* Kludge for F-Secure Macintosh < 1.0.2 */
479 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
483 if (buf[i] == '\n') {
488 buf[sizeof(buf) - 1] = 0;
489 client_version_string = xstrdup(buf);
492 * Check that the versions match. In future this might accept
493 * several versions and set appropriate flags to handle them.
495 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
496 &remote_major, &remote_minor, remote_version) != 3) {
497 s = "Protocol mismatch.\n";
498 (void) atomicio(vwrite, sock_out, s, strlen(s));
499 logit("Bad protocol version identification '%.100s' "
500 "from %s port %d", client_version_string,
501 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
506 debug("Client protocol version %d.%d; client software version %.100s",
507 remote_major, remote_minor, remote_version);
509 ssh->compat = compat_datafellows(remote_version);
511 if ((ssh->compat & SSH_BUG_PROBE) != 0) {
512 logit("probed from %s port %d with %s. Don't panic.",
513 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
514 client_version_string);
517 if ((ssh->compat & SSH_BUG_SCANNER) != 0) {
518 logit("scanned from %s port %d with %s. Don't panic.",
519 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
520 client_version_string);
523 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
524 logit("Client version \"%.100s\" uses unsafe RSA signature "
525 "scheme; disabling use of RSA keys", remote_version);
527 if ((ssh->compat & SSH_BUG_DERIVEKEY) != 0) {
528 fatal("Client version \"%.100s\" uses unsafe key agreement; "
529 "refusing connection", remote_version);
533 switch (remote_major) {
535 if (remote_minor == 99) {
536 if (options.protocol & SSH_PROTO_2)
542 if (!(options.protocol & SSH_PROTO_1)) {
546 if (remote_minor < 3) {
547 packet_disconnect("Your ssh version is too old and "
548 "is no longer supported. Please install a newer version.");
549 } else if (remote_minor == 3) {
550 /* note that this disables agent-forwarding */
555 if (options.protocol & SSH_PROTO_2) {
564 chop(server_version_string);
565 debug("Local version string %.200s", server_version_string);
568 s = "Protocol major versions differ.\n";
569 (void) atomicio(vwrite, sock_out, s, strlen(s));
572 logit("Protocol major versions differ for %s port %d: "
574 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
575 server_version_string, client_version_string);
580 /* Destroy the host and server keys. They will no longer be needed. */
582 destroy_sensitive_data(void)
586 if (sensitive_data.server_key) {
587 key_free(sensitive_data.server_key);
588 sensitive_data.server_key = NULL;
590 for (i = 0; i < options.num_host_key_files; i++) {
591 if (sensitive_data.host_keys[i]) {
592 key_free(sensitive_data.host_keys[i]);
593 sensitive_data.host_keys[i] = NULL;
595 if (sensitive_data.host_certificates[i]) {
596 key_free(sensitive_data.host_certificates[i]);
597 sensitive_data.host_certificates[i] = NULL;
600 sensitive_data.ssh1_host_key = NULL;
601 explicit_bzero(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
604 /* Demote private to public keys for network child */
606 demote_sensitive_data(void)
611 if (sensitive_data.server_key) {
612 tmp = key_demote(sensitive_data.server_key);
613 key_free(sensitive_data.server_key);
614 sensitive_data.server_key = tmp;
617 for (i = 0; i < options.num_host_key_files; i++) {
618 if (sensitive_data.host_keys[i]) {
619 tmp = key_demote(sensitive_data.host_keys[i]);
620 key_free(sensitive_data.host_keys[i]);
621 sensitive_data.host_keys[i] = tmp;
622 if (tmp->type == KEY_RSA1)
623 sensitive_data.ssh1_host_key = tmp;
625 /* Certs do not need demotion */
628 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
632 privsep_preauth_child(void)
637 /* Enable challenge-response authentication for privilege separation */
638 privsep_challenge_enable();
641 /* Cache supported mechanism OIDs for later use */
642 if (options.gss_authentication)
643 ssh_gssapi_prepare_supported_oids();
647 arc4random_buf(rnd, sizeof(rnd));
649 RAND_seed(rnd, sizeof(rnd));
650 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
651 fatal("%s: RAND_bytes failed", __func__);
653 explicit_bzero(rnd, sizeof(rnd));
655 /* Demote the private keys to public keys. */
656 demote_sensitive_data();
658 /* Demote the child */
659 if (getuid() == 0 || geteuid() == 0) {
660 /* Change our root directory */
661 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
662 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
664 if (chdir("/") == -1)
665 fatal("chdir(\"/\"): %s", strerror(errno));
667 /* Drop our privileges */
668 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
669 (u_int)privsep_pw->pw_gid);
670 gidset[0] = privsep_pw->pw_gid;
671 if (setgroups(1, gidset) < 0)
672 fatal("setgroups: %.100s", strerror(errno));
673 permanently_set_uid(privsep_pw);
678 privsep_preauth(Authctxt *authctxt)
682 struct ssh_sandbox *box = NULL;
684 /* Set up unprivileged child process to deal with network data */
685 pmonitor = monitor_init();
686 /* Store a pointer to the kex for later rekeying */
687 pmonitor->m_pkex = &active_state->kex;
689 if (use_privsep == PRIVSEP_ON)
690 box = ssh_sandbox_init(pmonitor);
693 fatal("fork of unprivileged child failed");
694 } else if (pid != 0) {
695 debug2("Network child is on pid %ld", (long)pid);
697 pmonitor->m_pid = pid;
699 r = ssh_get_authentication_socket(&auth_sock);
701 error("Could not get agent socket: %s",
707 ssh_sandbox_parent_preauth(box, pid);
708 monitor_child_preauth(authctxt, pmonitor);
711 monitor_sync(pmonitor);
713 /* Wait for the child's exit status */
714 while (waitpid(pid, &status, 0) < 0) {
717 pmonitor->m_pid = -1;
718 fatal("%s: waitpid: %s", __func__, strerror(errno));
720 privsep_is_preauth = 0;
721 pmonitor->m_pid = -1;
722 if (WIFEXITED(status)) {
723 if (WEXITSTATUS(status) != 0)
724 fatal("%s: preauth child exited with status %d",
725 __func__, WEXITSTATUS(status));
726 } else if (WIFSIGNALED(status))
727 fatal("%s: preauth child terminated by signal %d",
728 __func__, WTERMSIG(status));
730 ssh_sandbox_parent_finish(box);
734 close(pmonitor->m_sendfd);
735 close(pmonitor->m_log_recvfd);
737 /* Arrange for logging to be sent to the monitor */
738 set_log_handler(mm_log_handler, pmonitor);
740 privsep_preauth_child();
741 setproctitle("%s", "[net]");
743 ssh_sandbox_child(box);
750 privsep_postauth(Authctxt *authctxt)
754 #ifdef DISABLE_FD_PASSING
757 if (authctxt->pw->pw_uid == 0 || options.use_login) {
759 /* File descriptor passing is broken or root login */
764 /* New socket pair */
765 monitor_reinit(pmonitor);
767 pmonitor->m_pid = fork();
768 if (pmonitor->m_pid == -1)
769 fatal("fork of unprivileged child failed");
770 else if (pmonitor->m_pid != 0) {
771 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
772 buffer_clear(&loginmsg);
773 monitor_child_postauth(pmonitor);
781 close(pmonitor->m_sendfd);
782 pmonitor->m_sendfd = -1;
784 /* Demote the private keys to public keys. */
785 demote_sensitive_data();
788 arc4random_buf(rnd, sizeof(rnd));
790 RAND_seed(rnd, sizeof(rnd));
791 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
792 fatal("%s: RAND_bytes failed", __func__);
794 explicit_bzero(rnd, sizeof(rnd));
796 /* Drop privileges */
797 do_setusercontext(authctxt->pw);
800 /* It is safe now to apply the key state */
801 monitor_apply_keystate(pmonitor);
804 * Tell the packet layer that authentication was successful, since
805 * this information is not part of the key state.
807 packet_set_authenticated();
811 list_hostkey_types(void)
820 for (i = 0; i < options.num_host_key_files; i++) {
821 key = sensitive_data.host_keys[i];
823 key = sensitive_data.host_pubkeys[i];
824 if (key == NULL || key->type == KEY_RSA1)
826 /* Check that the key is accepted in HostkeyAlgorithms */
827 if (match_pattern_list(sshkey_ssh_name(key),
828 options.hostkeyalgorithms, 0) != 1) {
829 debug3("%s: %s key not permitted by HostkeyAlgorithms",
830 __func__, sshkey_ssh_name(key));
838 if (buffer_len(&b) > 0)
839 buffer_append(&b, ",", 1);
840 p = key_ssh_name(key);
841 buffer_append(&b, p, strlen(p));
843 /* for RSA we also support SHA2 signatures */
844 if (key->type == KEY_RSA) {
845 p = ",rsa-sha2-512,rsa-sha2-256";
846 buffer_append(&b, p, strlen(p));
850 /* If the private key has a cert peer, then list that too */
851 key = sensitive_data.host_certificates[i];
858 case KEY_ED25519_CERT:
859 if (buffer_len(&b) > 0)
860 buffer_append(&b, ",", 1);
861 p = key_ssh_name(key);
862 buffer_append(&b, p, strlen(p));
866 if ((ret = sshbuf_dup_string(&b)) == NULL)
867 fatal("%s: sshbuf_dup_string failed", __func__);
869 debug("list_hostkey_types: %s", ret);
874 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
879 for (i = 0; i < options.num_host_key_files; i++) {
884 case KEY_ED25519_CERT:
885 key = sensitive_data.host_certificates[i];
888 key = sensitive_data.host_keys[i];
889 if (key == NULL && !need_private)
890 key = sensitive_data.host_pubkeys[i];
893 if (key != NULL && key->type == type &&
894 (key->type != KEY_ECDSA || key->ecdsa_nid == nid))
895 return need_private ?
896 sensitive_data.host_keys[i] : key;
902 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
904 return get_hostkey_by_type(type, nid, 0, ssh);
908 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
910 return get_hostkey_by_type(type, nid, 1, ssh);
914 get_hostkey_by_index(int ind)
916 if (ind < 0 || ind >= options.num_host_key_files)
918 return (sensitive_data.host_keys[ind]);
922 get_hostkey_public_by_index(int ind, struct ssh *ssh)
924 if (ind < 0 || ind >= options.num_host_key_files)
926 return (sensitive_data.host_pubkeys[ind]);
930 get_hostkey_index(Key *key, int compare, struct ssh *ssh)
934 for (i = 0; i < options.num_host_key_files; i++) {
935 if (key_is_cert(key)) {
936 if (key == sensitive_data.host_certificates[i] ||
937 (compare && sensitive_data.host_certificates[i] &&
939 sensitive_data.host_certificates[i])))
942 if (key == sensitive_data.host_keys[i] ||
943 (compare && sensitive_data.host_keys[i] &&
944 sshkey_equal(key, sensitive_data.host_keys[i])))
946 if (key == sensitive_data.host_pubkeys[i] ||
947 (compare && sensitive_data.host_pubkeys[i] &&
948 sshkey_equal(key, sensitive_data.host_pubkeys[i])))
955 /* Inform the client of all hostkeys */
957 notify_hostkeys(struct ssh *ssh)
964 /* Some clients cannot cope with the hostkeys message, skip those. */
965 if (datafellows & SSH_BUG_HOSTKEYS)
968 if ((buf = sshbuf_new()) == NULL)
969 fatal("%s: sshbuf_new", __func__);
970 for (i = nkeys = 0; i < options.num_host_key_files; i++) {
971 key = get_hostkey_public_by_index(i, ssh);
972 if (key == NULL || key->type == KEY_UNSPEC ||
973 key->type == KEY_RSA1 || sshkey_is_cert(key))
975 fp = sshkey_fingerprint(key, options.fingerprint_hash,
977 debug3("%s: key %d: %s %s", __func__, i,
978 sshkey_ssh_name(key), fp);
981 packet_start(SSH2_MSG_GLOBAL_REQUEST);
982 packet_put_cstring("hostkeys-00@openssh.com");
983 packet_put_char(0); /* want-reply */
986 if ((r = sshkey_putb(key, buf)) != 0)
987 fatal("%s: couldn't put hostkey %d: %s",
988 __func__, i, ssh_err(r));
989 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf));
992 debug3("%s: sent %d hostkeys", __func__, nkeys);
994 fatal("%s: no hostkeys", __func__);
1000 * returns 1 if connection should be dropped, 0 otherwise.
1001 * dropping starts at connection #max_startups_begin with a probability
1002 * of (max_startups_rate/100). the probability increases linearly until
1003 * all connections are dropped for startups > max_startups
1006 drop_connection(int startups)
1010 if (startups < options.max_startups_begin)
1012 if (startups >= options.max_startups)
1014 if (options.max_startups_rate == 100)
1017 p = 100 - options.max_startups_rate;
1018 p *= startups - options.max_startups_begin;
1019 p /= options.max_startups - options.max_startups_begin;
1020 p += options.max_startups_rate;
1021 r = arc4random_uniform(100);
1023 debug("drop_connection: p %d, r %d", p, r);
1024 return (r < p) ? 1 : 0;
1030 if (options.version_addendum && *options.version_addendum != '\0')
1031 fprintf(stderr, "%s %s, %s\n",
1033 options.version_addendum, OPENSSL_VERSION);
1035 fprintf(stderr, "%s, %s\n",
1036 SSH_RELEASE, OPENSSL_VERSION);
1038 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
1039 " [-E log_file] [-f config_file] [-g login_grace_time]\n"
1040 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port]\n"
1047 send_rexec_state(int fd, struct sshbuf *conf)
1052 debug3("%s: entering fd = %d config len %zu", __func__, fd,
1056 * Protocol from reexec master to child:
1057 * string configuration
1058 * u_int ephemeral_key_follows
1059 * bignum e (only if ephemeral_key_follows == 1)
1065 * string rngseed (only if OpenSSL is not self-seeded)
1067 if ((m = sshbuf_new()) == NULL)
1068 fatal("%s: sshbuf_new failed", __func__);
1069 if ((r = sshbuf_put_stringb(m, conf)) != 0)
1070 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1073 if (sensitive_data.server_key != NULL &&
1074 sensitive_data.server_key->type == KEY_RSA1) {
1075 if ((r = sshbuf_put_u32(m, 1)) != 0 ||
1076 (r = sshbuf_put_bignum1(m,
1077 sensitive_data.server_key->rsa->e)) != 0 ||
1078 (r = sshbuf_put_bignum1(m,
1079 sensitive_data.server_key->rsa->n)) != 0 ||
1080 (r = sshbuf_put_bignum1(m,
1081 sensitive_data.server_key->rsa->d)) != 0 ||
1082 (r = sshbuf_put_bignum1(m,
1083 sensitive_data.server_key->rsa->iqmp)) != 0 ||
1084 (r = sshbuf_put_bignum1(m,
1085 sensitive_data.server_key->rsa->p)) != 0 ||
1086 (r = sshbuf_put_bignum1(m,
1087 sensitive_data.server_key->rsa->q)) != 0)
1088 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1091 if ((r = sshbuf_put_u32(m, 0)) != 0)
1092 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1094 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
1095 rexec_send_rng_seed(m);
1098 if (ssh_msg_send(fd, 0, m) == -1)
1099 fatal("%s: ssh_msg_send failed", __func__);
1103 debug3("%s: done", __func__);
1107 recv_rexec_state(int fd, Buffer *conf)
1113 debug3("%s: entering fd = %d", __func__, fd);
1117 if (ssh_msg_recv(fd, &m) == -1)
1118 fatal("%s: ssh_msg_recv failed", __func__);
1119 if (buffer_get_char(&m) != 0)
1120 fatal("%s: rexec version mismatch", __func__);
1122 cp = buffer_get_string(&m, &len);
1124 buffer_append(conf, cp, len);
1127 if (buffer_get_int(&m)) {
1129 if (sensitive_data.server_key != NULL)
1130 key_free(sensitive_data.server_key);
1131 sensitive_data.server_key = key_new_private(KEY_RSA1);
1132 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
1133 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
1134 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
1135 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
1136 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
1137 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
1138 if (rsa_generate_additional_parameters(
1139 sensitive_data.server_key->rsa) != 0)
1140 fatal("%s: rsa_generate_additional_parameters "
1145 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
1146 rexec_recv_rng_seed(&m);
1151 debug3("%s: done", __func__);
1154 /* Accept a connection from inetd */
1156 server_accept_inetd(int *sock_in, int *sock_out)
1162 close(REEXEC_CONFIG_PASS_FD);
1163 *sock_in = *sock_out = dup(STDIN_FILENO);
1165 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1166 close(REEXEC_STARTUP_PIPE_FD);
1169 *sock_in = dup(STDIN_FILENO);
1170 *sock_out = dup(STDOUT_FILENO);
1173 * We intentionally do not close the descriptors 0, 1, and 2
1174 * as our code for setting the descriptors won't work if
1175 * ttyfd happens to be one of those.
1177 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1178 dup2(fd, STDIN_FILENO);
1179 dup2(fd, STDOUT_FILENO);
1181 dup2(fd, STDERR_FILENO);
1182 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO))
1185 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1189 * Listen for TCP connections
1194 int ret, listen_sock, on = 1;
1195 struct addrinfo *ai;
1196 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1200 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1201 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1203 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1204 fatal("Too many listen sockets. "
1205 "Enlarge MAX_LISTEN_SOCKS");
1206 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1207 ntop, sizeof(ntop), strport, sizeof(strport),
1208 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1209 error("getnameinfo failed: %.100s",
1210 ssh_gai_strerror(ret));
1213 /* Create socket for listening. */
1214 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1216 if (listen_sock < 0) {
1217 /* kernel may not support ipv6 */
1218 verbose("socket: %.100s", strerror(errno));
1221 if (set_nonblock(listen_sock) == -1) {
1226 * Set socket options.
1227 * Allow local port reuse in TIME_WAIT.
1229 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1230 &on, sizeof(on)) == -1)
1231 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1233 /* Only communicate in IPv6 over AF_INET6 sockets. */
1234 if (ai->ai_family == AF_INET6)
1235 sock_set_v6only(listen_sock);
1237 debug("Bind to port %s on %s.", strport, ntop);
1239 len = sizeof(socksize);
1240 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len);
1241 debug("Server TCP RWIN socket size: %d", socksize);
1243 /* Bind the socket to the desired port. */
1244 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1245 error("Bind to port %s on %s failed: %.200s.",
1246 strport, ntop, strerror(errno));
1250 listen_socks[num_listen_socks] = listen_sock;
1253 /* Start listening on the port. */
1254 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1255 fatal("listen on [%s]:%s: %.100s",
1256 ntop, strport, strerror(errno));
1257 logit("Server listening on %s port %s.", ntop, strport);
1259 freeaddrinfo(options.listen_addrs);
1261 if (!num_listen_socks)
1262 fatal("Cannot bind any address.");
1266 * The main TCP accept loop. Note that, for the non-debug case, returns
1267 * from this function are in a forked subprocess.
1270 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1273 int i, j, ret, maxfd;
1274 int key_used = 0, startups = 0;
1275 int startup_p[2] = { -1 , -1 };
1276 struct sockaddr_storage from;
1281 /* setup fd set for accept */
1284 for (i = 0; i < num_listen_socks; i++)
1285 if (listen_socks[i] > maxfd)
1286 maxfd = listen_socks[i];
1287 /* pipes connected to unauthenticated childs */
1288 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1289 for (i = 0; i < options.max_startups; i++)
1290 startup_pipes[i] = -1;
1293 * Stay listening for connections until the system crashes or
1294 * the daemon is killed with a signal.
1297 if (received_sighup)
1300 fdset = xcalloc(howmany(maxfd + 1, NFDBITS),
1303 for (i = 0; i < num_listen_socks; i++)
1304 FD_SET(listen_socks[i], fdset);
1305 for (i = 0; i < options.max_startups; i++)
1306 if (startup_pipes[i] != -1)
1307 FD_SET(startup_pipes[i], fdset);
1309 /* Wait in select until there is a connection. */
1310 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1311 if (ret < 0 && errno != EINTR)
1312 error("select: %.100s", strerror(errno));
1313 if (received_sigterm) {
1314 logit("Received signal %d; terminating.",
1315 (int) received_sigterm);
1316 close_listen_socks();
1317 if (options.pid_file != NULL)
1318 unlink(options.pid_file);
1319 exit(received_sigterm == SIGTERM ? 0 : 255);
1321 if (key_used && key_do_regen) {
1322 generate_ephemeral_server_key();
1329 for (i = 0; i < options.max_startups; i++)
1330 if (startup_pipes[i] != -1 &&
1331 FD_ISSET(startup_pipes[i], fdset)) {
1333 * the read end of the pipe is ready
1334 * if the child has closed the pipe
1335 * after successful authentication
1336 * or if the child has died
1338 close(startup_pipes[i]);
1339 startup_pipes[i] = -1;
1342 for (i = 0; i < num_listen_socks; i++) {
1343 if (!FD_ISSET(listen_socks[i], fdset))
1345 fromlen = sizeof(from);
1346 *newsock = accept(listen_socks[i],
1347 (struct sockaddr *)&from, &fromlen);
1349 if (errno != EINTR && errno != EWOULDBLOCK &&
1350 errno != ECONNABORTED && errno != EAGAIN)
1351 error("accept: %.100s",
1353 if (errno == EMFILE || errno == ENFILE)
1357 if (unset_nonblock(*newsock) == -1) {
1361 if (drop_connection(startups) == 1) {
1362 debug("drop connection #%d", startups);
1366 if (pipe(startup_p) == -1) {
1371 if (rexec_flag && socketpair(AF_UNIX,
1372 SOCK_STREAM, 0, config_s) == -1) {
1373 error("reexec socketpair: %s",
1376 close(startup_p[0]);
1377 close(startup_p[1]);
1381 for (j = 0; j < options.max_startups; j++)
1382 if (startup_pipes[j] == -1) {
1383 startup_pipes[j] = startup_p[0];
1384 if (maxfd < startup_p[0])
1385 maxfd = startup_p[0];
1391 * Got connection. Fork a child to handle it, unless
1392 * we are in debugging mode.
1396 * In debugging mode. Close the listening
1397 * socket, and start processing the
1398 * connection without forking.
1400 debug("Server will not fork when running in debugging mode.");
1401 close_listen_socks();
1402 *sock_in = *newsock;
1403 *sock_out = *newsock;
1404 close(startup_p[0]);
1405 close(startup_p[1]);
1409 send_rexec_state(config_s[0],
1417 * Normal production daemon. Fork, and have
1418 * the child process the connection. The
1419 * parent continues listening.
1421 platform_pre_fork();
1422 if ((pid = fork()) == 0) {
1424 * Child. Close the listening and
1425 * max_startup sockets. Start using
1426 * the accepted socket. Reinitialize
1427 * logging (since our pid has changed).
1428 * We break out of the loop to handle
1431 platform_post_fork_child();
1432 startup_pipe = startup_p[1];
1433 close_startup_pipes();
1434 close_listen_socks();
1435 *sock_in = *newsock;
1436 *sock_out = *newsock;
1437 log_init(__progname,
1439 options.log_facility,
1446 /* Parent. Stay in the loop. */
1447 platform_post_fork_parent(pid);
1449 error("fork: %.100s", strerror(errno));
1451 debug("Forked child %ld.", (long)pid);
1453 close(startup_p[1]);
1456 send_rexec_state(config_s[0], &cfg);
1462 * Mark that the key has been used (it
1463 * was "given" to the child).
1465 if ((options.protocol & SSH_PROTO_1) &&
1467 /* Schedule server key regeneration alarm. */
1468 signal(SIGALRM, key_regeneration_alarm);
1469 alarm(options.key_regeneration_time);
1476 * Ensure that our random state differs
1477 * from that of the child
1480 arc4random_buf(rnd, sizeof(rnd));
1482 RAND_seed(rnd, sizeof(rnd));
1483 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
1484 fatal("%s: RAND_bytes failed", __func__);
1486 explicit_bzero(rnd, sizeof(rnd));
1489 /* child process check (or debug mode) */
1490 if (num_listen_socks < 0)
1496 * If IP options are supported, make sure there are none (log and
1497 * return an error if any are found). Basically we are worried about
1498 * source routing; it can be used to pretend you are somebody
1499 * (ip-address) you are not. That itself may be "almost acceptable"
1500 * under certain circumstances, but rhosts autentication is useless
1501 * if source routing is accepted. Notice also that if we just dropped
1502 * source routing here, the other side could use IP spoofing to do
1503 * rest of the interaction and could still bypass security. So we
1504 * exit here if we detect any IP options.
1507 check_ip_options(struct ssh *ssh)
1510 int sock_in = ssh_packet_get_connection_in(ssh);
1511 struct sockaddr_storage from;
1512 socklen_t option_size, i, fromlen = sizeof(from);
1514 char text[sizeof(opts) * 3 + 1];
1516 memset(&from, 0, sizeof(from));
1517 if (getpeername(sock_in, (struct sockaddr *)&from,
1520 if (from.ss_family != AF_INET)
1522 /* XXX IPv6 options? */
1524 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
1525 &option_size) >= 0 && option_size != 0) {
1527 for (i = 0; i < option_size; i++)
1528 snprintf(text + i*3, sizeof(text) - i*3,
1530 fatal("Connection from %.100s port %d with IP opts: %.800s",
1531 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
1534 #endif /* IP_OPTIONS */
1538 * Main program for the daemon.
1541 main(int ac, char **av)
1543 struct ssh *ssh = NULL;
1544 extern char *optarg;
1546 int r, opt, i, j, on = 1;
1547 int sock_in = -1, sock_out = -1, newsock = -1;
1548 const char *remote_ip;
1550 char *fp, *line, *laddr, *logfile = NULL;
1551 int config_s[2] = { -1 , -1 };
1553 u_int64_t ibytes, obytes;
1559 struct connection_info *connection_info = get_connection_info(0, 0);
1561 ssh_malloc_init(); /* must be called before any mallocs */
1563 #ifdef HAVE_SECUREWARE
1564 (void)set_auth_parameters(ac, av);
1566 __progname = ssh_get_progname(av[0]);
1568 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1571 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1572 for (i = 0; i < ac; i++)
1573 saved_argv[i] = xstrdup(av[i]);
1574 saved_argv[i] = NULL;
1576 #ifndef HAVE_SETPROCTITLE
1577 /* Prepare for later setproctitle emulation */
1578 compat_init_setproctitle(ac, av);
1582 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1583 debug("setgroups(): %.200s", strerror(errno));
1585 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1588 /* Initialize configuration options to their default values. */
1589 initialize_server_options(&options);
1591 /* Parse command-line arguments. */
1592 while ((opt = getopt(ac, av,
1593 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) {
1596 options.address_family = AF_INET;
1599 options.address_family = AF_INET6;
1602 config_file_name = optarg;
1605 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1606 fprintf(stderr, "too many host certificates.\n");
1609 options.host_cert_files[options.num_host_cert_files++] =
1610 derelativise_path(optarg);
1613 if (debug_flag == 0) {
1615 options.log_level = SYSLOG_LEVEL_DEBUG1;
1616 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1617 options.log_level++;
1642 options.log_level = SYSLOG_LEVEL_QUIET;
1645 options.server_key_bits = (int)strtonum(optarg, 256,
1649 options.ports_from_cmdline = 1;
1650 if (options.num_ports >= MAX_PORTS) {
1651 fprintf(stderr, "too many ports.\n");
1654 options.ports[options.num_ports++] = a2port(optarg);
1655 if (options.ports[options.num_ports-1] <= 0) {
1656 fprintf(stderr, "Bad port number.\n");
1661 if ((options.login_grace_time = convtime(optarg)) == -1) {
1662 fprintf(stderr, "Invalid login grace time.\n");
1667 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1668 fprintf(stderr, "Invalid key regeneration interval.\n");
1673 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1674 fprintf(stderr, "too many host keys.\n");
1677 options.host_key_files[options.num_host_key_files++] =
1678 derelativise_path(optarg);
1687 if (parse_server_match_testspec(connection_info,
1692 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1693 if (utmp_len > HOST_NAME_MAX+1) {
1694 fprintf(stderr, "Invalid utmp length.\n");
1699 line = xstrdup(optarg);
1700 if (process_server_config_line(&options, line,
1701 "command-line", 0, NULL, NULL) != 0)
1711 if (rexeced_flag || inetd_flag)
1713 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1714 fatal("sshd re-exec requires execution with an absolute path");
1716 closefrom(REEXEC_MIN_FREE_FD);
1718 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1721 OpenSSL_add_all_algorithms();
1724 /* If requested, redirect the logs to the specified logfile. */
1725 if (logfile != NULL)
1726 log_redirect_stderr_to(logfile);
1728 * Force logging to stderr until we have loaded the private host
1729 * key (unless started from inetd)
1731 log_init(__progname,
1732 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1733 SYSLOG_LEVEL_INFO : options.log_level,
1734 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1735 SYSLOG_FACILITY_AUTH : options.log_facility,
1736 log_stderr || !inetd_flag);
1739 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1740 * root's environment
1742 if (getenv("KRB5CCNAME") != NULL)
1743 (void) unsetenv("KRB5CCNAME");
1746 /* Cray can define user privs drop all privs now!
1747 * Not needed on PRIV_SU systems!
1752 sensitive_data.server_key = NULL;
1753 sensitive_data.ssh1_host_key = NULL;
1754 sensitive_data.have_ssh1_key = 0;
1755 sensitive_data.have_ssh2_key = 0;
1758 * If we're doing an extended config test, make sure we have all of
1759 * the parameters we need. If we're not doing an extended test,
1760 * do not silently ignore connection test params.
1762 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0)
1763 fatal("user, host and addr are all required when testing "
1765 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0)
1766 fatal("Config test connection parameter (-C) provided without "
1769 /* Fetch our configuration */
1772 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1773 else if (strcasecmp(config_file_name, "none") != 0)
1774 load_server_config(config_file_name, &cfg);
1776 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1781 /* Fill in default values for those options not explicitly set. */
1782 fill_default_server_options(&options);
1784 /* challenge-response is implemented via keyboard interactive */
1785 if (options.challenge_response_authentication)
1786 options.kbd_interactive_authentication = 1;
1788 /* Check that options are sensible */
1789 if (options.authorized_keys_command_user == NULL &&
1790 (options.authorized_keys_command != NULL &&
1791 strcasecmp(options.authorized_keys_command, "none") != 0))
1792 fatal("AuthorizedKeysCommand set without "
1793 "AuthorizedKeysCommandUser");
1794 if (options.authorized_principals_command_user == NULL &&
1795 (options.authorized_principals_command != NULL &&
1796 strcasecmp(options.authorized_principals_command, "none") != 0))
1797 fatal("AuthorizedPrincipalsCommand set without "
1798 "AuthorizedPrincipalsCommandUser");
1801 * Check whether there is any path through configured auth methods.
1802 * Unfortunately it is not possible to verify this generally before
1803 * daemonisation in the presence of Match block, but this catches
1804 * and warns for trivial misconfigurations that could break login.
1806 if (options.num_auth_methods != 0) {
1807 if ((options.protocol & SSH_PROTO_1))
1808 fatal("AuthenticationMethods is not supported with "
1810 for (n = 0; n < options.num_auth_methods; n++) {
1811 if (auth2_methods_valid(options.auth_methods[n],
1815 if (n >= options.num_auth_methods)
1816 fatal("AuthenticationMethods cannot be satisfied by "
1817 "enabled authentication methods");
1820 /* set default channel AF */
1821 channel_set_af(options.address_family);
1823 /* Check that there are no remaining arguments. */
1825 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1829 debug("sshd version %s, %s", SSH_VERSION,
1831 SSLeay_version(SSLEAY_VERSION)
1837 /* Store privilege separation user for later use if required. */
1838 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1839 if (use_privsep || options.kerberos_authentication)
1840 fatal("Privilege separation user %s does not exist",
1843 explicit_bzero(privsep_pw->pw_passwd,
1844 strlen(privsep_pw->pw_passwd));
1845 privsep_pw = pwcopy(privsep_pw);
1846 free(privsep_pw->pw_passwd);
1847 privsep_pw->pw_passwd = xstrdup("*");
1851 /* load host keys */
1852 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1854 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1857 if (options.host_key_agent) {
1858 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1859 setenv(SSH_AUTHSOCKET_ENV_NAME,
1860 options.host_key_agent, 1);
1861 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1864 error("Could not connect to agent \"%s\": %s",
1865 options.host_key_agent, ssh_err(r));
1868 for (i = 0; i < options.num_host_key_files; i++) {
1869 if (options.host_key_files[i] == NULL)
1871 key = key_load_private(options.host_key_files[i], "", NULL);
1872 pubkey = key_load_public(options.host_key_files[i], NULL);
1873 if (pubkey == NULL && key != NULL)
1874 pubkey = key_demote(key);
1875 sensitive_data.host_keys[i] = key;
1876 sensitive_data.host_pubkeys[i] = pubkey;
1878 if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 &&
1880 debug("will rely on agent for hostkey %s",
1881 options.host_key_files[i]);
1882 keytype = pubkey->type;
1883 } else if (key != NULL) {
1884 keytype = key->type;
1886 error("Could not load host key: %s",
1887 options.host_key_files[i]);
1888 sensitive_data.host_keys[i] = NULL;
1889 sensitive_data.host_pubkeys[i] = NULL;
1895 sensitive_data.ssh1_host_key = key;
1896 sensitive_data.have_ssh1_key = 1;
1902 if (have_agent || key != NULL)
1903 sensitive_data.have_ssh2_key = 1;
1906 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
1907 SSH_FP_DEFAULT)) == NULL)
1908 fatal("sshkey_fingerprint failed");
1909 debug("%s host key #%d: %s %s",
1910 key ? "private" : "agent", i, keytype == KEY_RSA1 ?
1911 sshkey_type(pubkey) : sshkey_ssh_name(pubkey), fp);
1914 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1915 logit("Disabling protocol version 1. Could not load host key");
1916 options.protocol &= ~SSH_PROTO_1;
1918 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1919 logit("Disabling protocol version 2. Could not load host key");
1920 options.protocol &= ~SSH_PROTO_2;
1922 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1923 logit("sshd: no hostkeys available -- exiting.");
1928 * Load certificates. They are stored in an array at identical
1929 * indices to the public keys that they relate to.
1931 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1933 for (i = 0; i < options.num_host_key_files; i++)
1934 sensitive_data.host_certificates[i] = NULL;
1936 for (i = 0; i < options.num_host_cert_files; i++) {
1937 if (options.host_cert_files[i] == NULL)
1939 key = key_load_public(options.host_cert_files[i], NULL);
1941 error("Could not load host certificate: %s",
1942 options.host_cert_files[i]);
1945 if (!key_is_cert(key)) {
1946 error("Certificate file is not a certificate: %s",
1947 options.host_cert_files[i]);
1951 /* Find matching private key */
1952 for (j = 0; j < options.num_host_key_files; j++) {
1953 if (key_equal_public(key,
1954 sensitive_data.host_keys[j])) {
1955 sensitive_data.host_certificates[j] = key;
1959 if (j >= options.num_host_key_files) {
1960 error("No matching private key for certificate: %s",
1961 options.host_cert_files[i]);
1965 sensitive_data.host_certificates[j] = key;
1966 debug("host certificate: #%d type %d %s", j, key->type,
1971 /* Check certain values for sanity. */
1972 if (options.protocol & SSH_PROTO_1) {
1973 if (options.server_key_bits < SSH_RSA_MINIMUM_MODULUS_SIZE ||
1974 options.server_key_bits > OPENSSL_RSA_MAX_MODULUS_BITS) {
1975 fprintf(stderr, "Bad server key size.\n");
1979 * Check that server and host key lengths differ sufficiently. This
1980 * is necessary to make double encryption work with rsaref. Oh, I
1981 * hate software patents. I dont know if this can go? Niels
1983 if (options.server_key_bits >
1984 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1985 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1986 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1987 SSH_KEY_BITS_RESERVED) {
1988 options.server_key_bits =
1989 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1990 SSH_KEY_BITS_RESERVED;
1991 debug("Forcing server key to %d bits to make it differ from host key.",
1992 options.server_key_bits);
2000 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
2001 (S_ISDIR(st.st_mode) == 0))
2002 fatal("Missing privilege separation directory: %s",
2003 _PATH_PRIVSEP_CHROOT_DIR);
2006 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
2007 (st.st_uid != getuid () ||
2008 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
2010 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
2012 fatal("%s must be owned by root and not group or "
2013 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
2016 if (test_flag > 1) {
2017 if (server_match_spec_complete(connection_info) == 1)
2018 parse_server_match_config(&options, connection_info);
2019 dump_config(&options);
2022 /* Configuration looks good, so exit if in test mode. */
2027 * Clear out any supplemental groups we may have inherited. This
2028 * prevents inadvertent creation of files with bad modes (in the
2029 * portable version at least, it's certainly possible for PAM
2030 * to create a file, and we can't control the code in every
2031 * module which might be used).
2033 if (setgroups(0, NULL) < 0)
2034 debug("setgroups() failed: %.200s", strerror(errno));
2037 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
2038 for (i = 0; i < rexec_argc; i++) {
2039 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
2040 rexec_argv[i] = saved_argv[i];
2042 rexec_argv[rexec_argc] = "-R";
2043 rexec_argv[rexec_argc + 1] = NULL;
2046 /* Ensure that umask disallows at least group and world write */
2047 new_umask = umask(0077) | 0022;
2048 (void) umask(new_umask);
2050 /* Initialize the log (it is reinitialized below in case we forked). */
2051 if (debug_flag && (!inetd_flag || rexeced_flag))
2053 log_init(__progname, options.log_level, options.log_facility, log_stderr);
2056 * If not in debugging mode, and not started from inetd, disconnect
2057 * from the controlling terminal, and fork. The original process
2060 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
2063 #endif /* TIOCNOTTY */
2064 if (daemon(0, 0) < 0)
2065 fatal("daemon() failed: %.200s", strerror(errno));
2067 /* Disconnect from the controlling tty. */
2069 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
2071 (void) ioctl(fd, TIOCNOTTY, NULL);
2074 #endif /* TIOCNOTTY */
2076 /* Reinitialize the log (because of the fork above). */
2077 log_init(__progname, options.log_level, options.log_facility, log_stderr);
2079 /* Avoid killing the process in high-pressure swapping environments. */
2080 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0)
2081 debug("madvise(): %.200s", strerror(errno));
2083 /* Chdir to the root directory so that the current disk can be
2084 unmounted if desired. */
2085 if (chdir("/") == -1)
2086 error("chdir(\"/\"): %s", strerror(errno));
2088 /* ignore SIGPIPE */
2089 signal(SIGPIPE, SIG_IGN);
2091 /* Get a connection, either from inetd or a listening TCP socket */
2093 server_accept_inetd(&sock_in, &sock_out);
2095 platform_pre_listen();
2098 if (options.protocol & SSH_PROTO_1)
2099 generate_ephemeral_server_key();
2101 signal(SIGHUP, sighup_handler);
2102 signal(SIGCHLD, main_sigchld_handler);
2103 signal(SIGTERM, sigterm_handler);
2104 signal(SIGQUIT, sigterm_handler);
2107 * Write out the pid file after the sigterm handler
2108 * is setup and the listen sockets are bound
2110 if (options.pid_file != NULL && !debug_flag) {
2111 FILE *f = fopen(options.pid_file, "w");
2114 error("Couldn't create pid file \"%s\": %s",
2115 options.pid_file, strerror(errno));
2117 fprintf(f, "%ld\n", (long) getpid());
2122 /* Accept a connection and return in a forked child */
2123 server_accept_loop(&sock_in, &sock_out,
2124 &newsock, config_s);
2127 /* This is the child processing a new connection. */
2128 setproctitle("%s", "[accepted]");
2131 * Create a new session and process group since the 4.4BSD
2132 * setlogin() affects the entire process group. We don't
2133 * want the child to be able to affect the parent.
2135 #if !defined(SSHD_ACQUIRES_CTTY)
2137 * If setsid is called, on some platforms sshd will later acquire a
2138 * controlling terminal which will result in "could not set
2139 * controlling tty" errors.
2141 if (!debug_flag && !inetd_flag && setsid() < 0)
2142 error("setsid: %.100s", strerror(errno));
2148 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
2149 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2150 dup2(newsock, STDIN_FILENO);
2151 dup2(STDIN_FILENO, STDOUT_FILENO);
2152 if (startup_pipe == -1)
2153 close(REEXEC_STARTUP_PIPE_FD);
2154 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
2155 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
2156 close(startup_pipe);
2157 startup_pipe = REEXEC_STARTUP_PIPE_FD;
2160 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
2163 execv(rexec_argv[0], rexec_argv);
2165 /* Reexec has failed, fall back and continue */
2166 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
2167 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
2168 log_init(__progname, options.log_level,
2169 options.log_facility, log_stderr);
2172 close(REEXEC_CONFIG_PASS_FD);
2173 newsock = sock_out = sock_in = dup(STDIN_FILENO);
2174 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
2175 dup2(fd, STDIN_FILENO);
2176 dup2(fd, STDOUT_FILENO);
2177 if (fd > STDERR_FILENO)
2180 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
2181 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2184 /* Executed child processes don't need these. */
2185 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
2186 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
2189 * Disable the key regeneration alarm. We will not regenerate the
2190 * key since we are no longer in a position to give it to anyone. We
2191 * will not restart on SIGHUP since it no longer makes sense.
2194 signal(SIGALRM, SIG_DFL);
2195 signal(SIGHUP, SIG_DFL);
2196 signal(SIGTERM, SIG_DFL);
2197 signal(SIGQUIT, SIG_DFL);
2198 signal(SIGCHLD, SIG_DFL);
2199 signal(SIGINT, SIG_DFL);
2203 * Initialize the resolver. This may not happen automatically
2204 * before privsep chroot().
2206 if ((_res.options & RES_INIT) == 0) {
2207 debug("res_init()");
2212 * Force GSS-API to parse its configuration and load any
2213 * mechanism plugins.
2217 OM_uint32 minor_status;
2218 gss_indicate_mechs(&minor_status, &mechs);
2219 gss_release_oid_set(&minor_status, &mechs);
2225 * Register our connection. This turns encryption off because we do
2228 packet_set_connection(sock_in, sock_out);
2229 packet_set_server();
2230 ssh = active_state; /* XXX */
2231 check_ip_options(ssh);
2233 /* Set SO_KEEPALIVE if requested. */
2234 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
2235 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
2236 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
2238 if ((remote_port = ssh_remote_port(ssh)) < 0) {
2239 debug("ssh_remote_port failed");
2244 * The rest of the code depends on the fact that
2245 * ssh_remote_ipaddr() caches the remote ip, even if
2246 * the socket goes away.
2248 remote_ip = ssh_remote_ipaddr(ssh);
2250 #ifdef SSH_AUDIT_EVENTS
2251 audit_connection_from(remote_ip, remote_port);
2254 allow_severity = options.log_facility|LOG_INFO;
2255 deny_severity = options.log_facility|LOG_WARNING;
2256 /* Check whether logins are denied from this host. */
2257 if (packet_connection_is_on_socket()) {
2258 struct request_info req;
2260 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
2263 if (!hosts_access(&req)) {
2264 debug("Connection refused by tcp wrapper");
2267 fatal("libwrap refuse returns");
2270 #endif /* LIBWRAP */
2272 /* Log the connection. */
2273 laddr = get_local_ipaddr(sock_in);
2274 verbose("Connection from %s port %d on %s port %d",
2275 remote_ip, remote_port, laddr, ssh_local_port(ssh));
2279 * We don't want to listen forever unless the other side
2280 * successfully authenticates itself. So we set up an alarm which is
2281 * cleared after successful authentication. A limit of zero
2282 * indicates no limit. Note that we don't set the alarm in debugging
2283 * mode; it is just annoying to have the server exit just when you
2284 * are about to discover the bug.
2286 signal(SIGALRM, grace_alarm_handler);
2288 alarm(options.login_grace_time);
2290 sshd_exchange_identification(ssh, sock_in, sock_out);
2292 /* In inetd mode, generate ephemeral key only for proto 1 connections */
2293 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
2294 generate_ephemeral_server_key();
2296 packet_set_nonblocking();
2298 /* allocate authentication context */
2299 authctxt = xcalloc(1, sizeof(*authctxt));
2301 authctxt->loginmsg = &loginmsg;
2303 /* XXX global for cleanup, access from other modules */
2304 the_authctxt = authctxt;
2306 /* prepare buffer to collect messages to display to user after login */
2307 buffer_init(&loginmsg);
2311 if (privsep_preauth(authctxt) == 1)
2313 } else if (compat20 && have_agent) {
2314 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
2315 error("Unable to get agent socket: %s", ssh_err(r));
2320 /* perform the key exchange */
2321 /* authenticate user and start session */
2324 do_authentication2(authctxt);
2328 do_authentication(authctxt);
2330 fatal("ssh1 not supported");
2334 * If we use privilege separation, the unprivileged child transfers
2335 * the current keystate and exits
2338 mm_send_keystate(pmonitor);
2344 * Cancel the alarm we set to limit the time taken for
2348 signal(SIGALRM, SIG_DFL);
2349 authctxt->authenticated = 1;
2350 if (startup_pipe != -1) {
2351 close(startup_pipe);
2355 #ifdef SSH_AUDIT_EVENTS
2356 audit_event(SSH_AUTH_SUCCESS);
2360 if (options.gss_authentication) {
2361 temporarily_use_uid(authctxt->pw);
2362 ssh_gssapi_storecreds();
2367 if (options.use_pam) {
2374 * In privilege separation, we fork another child and prepare
2375 * file descriptor passing.
2378 privsep_postauth(authctxt);
2379 /* the monitor process [priv] will not return */
2381 destroy_sensitive_data();
2384 packet_set_timeout(options.client_alive_interval,
2385 options.client_alive_count_max);
2387 /* Try to send all our hostkeys to the client */
2389 notify_hostkeys(active_state);
2391 /* Start session. */
2392 do_authenticated(authctxt);
2394 /* The connection has been terminated. */
2395 packet_get_bytes(&ibytes, &obytes);
2396 verbose("Transferred: sent %llu, received %llu bytes",
2397 (unsigned long long)obytes, (unsigned long long)ibytes);
2399 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2402 if (options.use_pam)
2404 #endif /* USE_PAM */
2406 #ifdef SSH_AUDIT_EVENTS
2407 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2420 * Decrypt session_key_int using our private server key and private host key
2421 * (key with larger modulus first).
2424 ssh1_session_key(BIGNUM *session_key_int)
2426 struct ssh *ssh = active_state; /* XXX */
2429 if (BN_cmp(sensitive_data.server_key->rsa->n,
2430 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2431 /* Server key has bigger modulus. */
2432 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2433 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2434 SSH_KEY_BITS_RESERVED) {
2435 fatal("do_connection: %s port %d: "
2436 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2437 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
2438 BN_num_bits(sensitive_data.server_key->rsa->n),
2439 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2440 SSH_KEY_BITS_RESERVED);
2442 if (rsa_private_decrypt(session_key_int, session_key_int,
2443 sensitive_data.server_key->rsa) != 0)
2445 if (rsa_private_decrypt(session_key_int, session_key_int,
2446 sensitive_data.ssh1_host_key->rsa) != 0)
2449 /* Host key has bigger modulus (or they are equal). */
2450 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2451 BN_num_bits(sensitive_data.server_key->rsa->n) +
2452 SSH_KEY_BITS_RESERVED) {
2453 fatal("do_connection: %s port %d: "
2454 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2455 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
2456 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2457 BN_num_bits(sensitive_data.server_key->rsa->n),
2458 SSH_KEY_BITS_RESERVED);
2460 if (rsa_private_decrypt(session_key_int, session_key_int,
2461 sensitive_data.ssh1_host_key->rsa) != 0)
2463 if (rsa_private_decrypt(session_key_int, session_key_int,
2464 sensitive_data.server_key->rsa) != 0)
2476 struct ssh *ssh = active_state; /* XXX */
2479 BIGNUM *session_key_int, *fake_key_int, *real_key_int;
2480 u_char session_key[SSH_SESSION_KEY_LENGTH];
2481 u_char fake_key_bytes[4096 / 8];
2482 size_t fake_key_len;
2484 u_int cipher_type, auth_mask, protocol_flags;
2487 * Generate check bytes that the client must send back in the user
2488 * packet in order for it to be accepted; this is used to defy ip
2489 * spoofing attacks. Note that this only works against somebody
2490 * doing IP spoofing from a remote machine; any machine on the local
2491 * network can still see outgoing packets and catch the random
2492 * cookie. This only affects rhosts authentication, and this is one
2493 * of the reasons why it is inherently insecure.
2495 arc4random_buf(cookie, sizeof(cookie));
2498 * Send our public key. We include in the packet 64 bits of random
2499 * data that must be matched in the reply in order to prevent IP
2502 packet_start(SSH_SMSG_PUBLIC_KEY);
2503 for (i = 0; i < 8; i++)
2504 packet_put_char(cookie[i]);
2506 /* Store our public server RSA key. */
2507 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2508 packet_put_bignum(sensitive_data.server_key->rsa->e);
2509 packet_put_bignum(sensitive_data.server_key->rsa->n);
2511 /* Store our public host RSA key. */
2512 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2513 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2514 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2516 /* Put protocol flags. */
2517 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2519 /* Declare which ciphers we support. */
2520 packet_put_int(cipher_mask_ssh1(0));
2522 /* Declare supported authentication types. */
2524 if (options.rhosts_rsa_authentication)
2525 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2526 if (options.rsa_authentication)
2527 auth_mask |= 1 << SSH_AUTH_RSA;
2528 if (options.challenge_response_authentication == 1)
2529 auth_mask |= 1 << SSH_AUTH_TIS;
2530 if (options.password_authentication)
2531 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2532 packet_put_int(auth_mask);
2534 /* Send the packet and wait for it to be sent. */
2536 packet_write_wait();
2538 debug("Sent %d bit server key and %d bit host key.",
2539 BN_num_bits(sensitive_data.server_key->rsa->n),
2540 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2542 /* Read clients reply (cipher type and session key). */
2543 packet_read_expect(SSH_CMSG_SESSION_KEY);
2545 /* Get cipher type and check whether we accept this. */
2546 cipher_type = packet_get_char();
2548 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2549 packet_disconnect("Warning: client selects unsupported cipher.");
2551 /* Get check bytes from the packet. These must match those we
2552 sent earlier with the public key packet. */
2553 for (i = 0; i < 8; i++)
2554 if (cookie[i] != packet_get_char())
2555 packet_disconnect("IP Spoofing check bytes do not match.");
2557 debug("Encryption type: %.200s", cipher_name(cipher_type));
2559 /* Get the encrypted integer. */
2560 if ((real_key_int = BN_new()) == NULL)
2561 fatal("do_ssh1_kex: BN_new failed");
2562 packet_get_bignum(real_key_int);
2564 protocol_flags = packet_get_int();
2565 packet_set_protocol_flags(protocol_flags);
2568 /* Setup a fake key in case RSA decryption fails */
2569 if ((fake_key_int = BN_new()) == NULL)
2570 fatal("do_ssh1_kex: BN_new failed");
2571 fake_key_len = BN_num_bytes(real_key_int);
2572 if (fake_key_len > sizeof(fake_key_bytes))
2573 fake_key_len = sizeof(fake_key_bytes);
2574 arc4random_buf(fake_key_bytes, fake_key_len);
2575 if (BN_bin2bn(fake_key_bytes, fake_key_len, fake_key_int) == NULL)
2576 fatal("do_ssh1_kex: BN_bin2bn failed");
2578 /* Decrypt real_key_int using host/server keys */
2579 rsafail = PRIVSEP(ssh1_session_key(real_key_int));
2580 /* If decryption failed, use the fake key. Else, the real key. */
2582 session_key_int = fake_key_int;
2584 session_key_int = real_key_int;
2587 * Extract session key from the decrypted integer. The key is in the
2588 * least significant 256 bits of the integer; the first byte of the
2589 * key is in the highest bits.
2591 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2592 len = BN_num_bytes(session_key_int);
2593 if (len < 0 || (u_int)len > sizeof(session_key)) {
2594 error("%s: bad session key len from %s port %d: "
2595 "session_key_int %d > sizeof(session_key) %lu", __func__,
2596 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
2597 len, (u_long)sizeof(session_key));
2600 explicit_bzero(session_key, sizeof(session_key));
2601 BN_bn2bin(session_key_int,
2602 session_key + sizeof(session_key) - len);
2604 derive_ssh1_session_id(
2605 sensitive_data.ssh1_host_key->rsa->n,
2606 sensitive_data.server_key->rsa->n,
2607 cookie, session_id);
2609 * Xor the first 16 bytes of the session key with the
2612 for (i = 0; i < 16; i++)
2613 session_key[i] ^= session_id[i];
2616 /* Destroy the private and public keys. No longer. */
2617 destroy_sensitive_data();
2620 mm_ssh1_session_id(session_id);
2622 /* Destroy the decrypted integer. It is no longer needed. */
2623 BN_clear_free(real_key_int);
2624 BN_clear_free(fake_key_int);
2626 /* Set the session key. From this on all communications will be encrypted. */
2627 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2629 /* Destroy our copy of the session key. It is no longer needed. */
2630 explicit_bzero(session_key, sizeof(session_key));
2632 debug("Received session key; encryption turned on.");
2634 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2635 packet_start(SSH_SMSG_SUCCESS);
2637 packet_write_wait();
2642 sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, size_t *slen,
2643 const u_char *data, size_t dlen, const char *alg, u_int flag)
2646 u_int xxx_slen, xxx_dlen = dlen;
2649 if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen,
2651 fatal("%s: key_sign failed", __func__);
2654 } else if (use_privsep) {
2655 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen,
2657 fatal("%s: pubkey_sign failed", __func__);
2661 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen,
2662 data, dlen, alg, datafellows)) != 0)
2663 fatal("%s: ssh_agent_sign failed: %s",
2664 __func__, ssh_err(r));
2669 /* SSH2 key exchange */
2673 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
2677 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
2678 options.kex_algorithms);
2679 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
2681 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
2683 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2684 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2686 if (options.compression == COMP_NONE) {
2687 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2688 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2689 } else if (options.compression == COMP_DELAYED) {
2690 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2691 myproposal[PROPOSAL_COMP_ALGS_STOC] =
2692 "none,zlib@openssh.com";
2695 if (options.rekey_limit || options.rekey_interval)
2696 packet_set_rekey_limits(options.rekey_limit,
2697 (time_t)options.rekey_interval);
2699 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
2700 list_hostkey_types());
2702 /* start key exchange */
2703 if ((r = kex_setup(active_state, myproposal)) != 0)
2704 fatal("kex_setup: %s", ssh_err(r));
2705 kex = active_state->kex;
2707 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2708 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2709 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
2710 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
2711 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
2712 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2713 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2714 # ifdef OPENSSL_HAS_ECC
2715 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2718 kex->kex[KEX_C25519_SHA256] = kexc25519_server;
2720 kex->client_version_string=client_version_string;
2721 kex->server_version_string=server_version_string;
2722 kex->load_host_public_key=&get_hostkey_public_by_type;
2723 kex->load_host_private_key=&get_hostkey_private_by_type;
2724 kex->host_key_index=&get_hostkey_index;
2725 kex->sign = sshd_hostkey_sign;
2727 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state);
2729 session_id2 = kex->session_id;
2730 session_id2_len = kex->session_id_len;
2733 /* send 1st encrypted/maced/compressed message */
2734 packet_start(SSH2_MSG_IGNORE);
2735 packet_put_cstring("markus");
2737 packet_write_wait();
2742 /* server specific fatal cleanup */
2747 do_cleanup(the_authctxt);
2748 if (use_privsep && privsep_is_preauth &&
2749 pmonitor != NULL && pmonitor->m_pid > 1) {
2750 debug("Killing privsep child %d", pmonitor->m_pid);
2751 if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2753 error("%s: kill(%d): %s", __func__,
2754 pmonitor->m_pid, strerror(errno));
2757 #ifdef SSH_AUDIT_EVENTS
2758 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2759 if (!use_privsep || mm_is_monitor())
2760 audit_event(SSH_CONNECTION_ABANDON);