1 /* $OpenBSD: sshd.c,v 1.506 2018/03/03 03:15:51 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.
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)
108 #include "servconf.h"
115 #include "myproposal.h"
116 #include "authfile.h"
117 #include "pathnames.h"
118 #include "atomicio.h"
119 #include "canohost.h"
120 #include "hostfile.h"
124 #include "dispatch.h"
125 #include "channels.h"
131 #include "monitor_wrap.h"
132 #include "ssh-sandbox.h"
133 #include "auth-options.h"
136 #include "blacklist_client.h"
146 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
147 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
148 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
149 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
151 extern char *__progname;
153 /* Server configuration options. */
154 ServerOptions options;
156 /* Name of the server configuration file. */
157 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
160 * Debug mode flag. This can be set on the command line. If debug
161 * mode is enabled, extra debugging output will be sent to the system
162 * log, the daemon will not go to background, and will exit after processing
163 * the first connection.
168 * Indicating that the daemon should only test the configuration and keys.
169 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective
170 * configuration, optionally using connection information provided by the
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 struct sshkey **host_keys; /* all private host keys */
223 struct sshkey **host_pubkeys; /* all public host keys */
224 struct sshkey **host_certificates; /* all public host certificates */
228 /* This is set to true when a signal is received. */
229 static volatile sig_atomic_t received_sighup = 0;
230 static volatile sig_atomic_t received_sigterm = 0;
232 /* session identifier, used by RSA-auth */
233 u_char session_id[16];
236 u_char *session_id2 = NULL;
237 u_int session_id2_len = 0;
239 /* record remote hostname or ip */
240 u_int utmp_len = HOST_NAME_MAX+1;
242 /* options.max_startup sized array of fd ints */
243 int *startup_pipes = NULL;
244 int startup_pipe; /* in child */
246 /* variables used for privilege separation */
247 int use_privsep = -1;
248 struct monitor *pmonitor = NULL;
249 int privsep_is_preauth = 1;
250 static int privsep_chroot = 1;
252 /* global authentication context */
253 Authctxt *the_authctxt = NULL;
255 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */
256 struct sshauthopt *auth_opts = NULL;
258 /* sshd_config buffer */
261 /* message to be displayed after login */
264 /* Unprivileged user */
265 struct passwd *privsep_pw = NULL;
267 /* Prototypes for various functions defined later in this file. */
268 void destroy_sensitive_data(void);
269 void demote_sensitive_data(void);
270 static void do_ssh2_kex(void);
273 * Close all listening sockets
276 close_listen_socks(void)
280 for (i = 0; i < num_listen_socks; i++)
281 close(listen_socks[i]);
282 num_listen_socks = -1;
286 close_startup_pipes(void)
291 for (i = 0; i < options.max_startups; i++)
292 if (startup_pipes[i] != -1)
293 close(startup_pipes[i]);
297 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
298 * the effect is to reread the configuration file (and to regenerate
304 sighup_handler(int sig)
306 int save_errno = errno;
313 * Called from the main program after receiving SIGHUP.
314 * Restarts the server.
319 logit("Received SIGHUP; restarting.");
320 if (options.pid_file != NULL)
321 unlink(options.pid_file);
322 platform_pre_restart();
323 close_listen_socks();
324 close_startup_pipes();
325 alarm(0); /* alarm timer persists across exec */
326 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
327 execv(saved_argv[0], saved_argv);
328 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
334 * Generic signal handler for terminating signals in the master daemon.
338 sigterm_handler(int sig)
340 received_sigterm = sig;
344 * SIGCHLD handler. This is called whenever a child dies. This will then
345 * reap any zombies left by exited children.
349 main_sigchld_handler(int sig)
351 int save_errno = errno;
355 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
356 (pid < 0 && errno == EINTR))
362 * Signal handler for the alarm after the login grace period has expired.
366 grace_alarm_handler(int sig)
368 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
369 kill(pmonitor->m_pid, SIGALRM);
372 * Try to kill any processes that we have spawned, E.g. authorized
373 * keys command helpers.
375 if (getpgid(0) == getpid()) {
376 signal(SIGTERM, SIG_IGN);
380 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh");
382 /* Log error and exit. */
383 sigdie("Timeout before authentication for %s port %d",
384 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state));
388 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out)
391 int remote_major, remote_minor;
393 char buf[256]; /* Must not be larger than remote_version. */
394 char remote_version[256]; /* Must be at least as big as buf. */
396 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n",
397 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
398 *options.version_addendum == '\0' ? "" : " ",
399 options.version_addendum);
401 /* Send our protocol version identification. */
402 if (atomicio(vwrite, sock_out, server_version_string,
403 strlen(server_version_string))
404 != strlen(server_version_string)) {
405 logit("Could not write ident string to %s port %d",
406 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
410 /* Read other sides version identification. */
411 memset(buf, 0, sizeof(buf));
412 for (i = 0; i < sizeof(buf) - 1; i++) {
413 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
414 logit("Did not receive identification string "
416 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
419 if (buf[i] == '\r') {
421 /* Kludge for F-Secure Macintosh < 1.0.2 */
423 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
427 if (buf[i] == '\n') {
432 buf[sizeof(buf) - 1] = 0;
433 client_version_string = xstrdup(buf);
436 * Check that the versions match. In future this might accept
437 * several versions and set appropriate flags to handle them.
439 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
440 &remote_major, &remote_minor, remote_version) != 3) {
441 s = "Protocol mismatch.\n";
442 (void) atomicio(vwrite, sock_out, s, strlen(s));
443 logit("Bad protocol version identification '%.100s' "
444 "from %s port %d", client_version_string,
445 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
450 debug("Client protocol version %d.%d; client software version %.100s",
451 remote_major, remote_minor, remote_version);
453 ssh->compat = compat_datafellows(remote_version);
455 if ((ssh->compat & SSH_BUG_PROBE) != 0) {
456 logit("probed from %s port %d with %s. Don't panic.",
457 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
458 client_version_string);
461 if ((ssh->compat & SSH_BUG_SCANNER) != 0) {
462 logit("scanned from %s port %d with %s. Don't panic.",
463 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
464 client_version_string);
467 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
468 logit("Client version \"%.100s\" uses unsafe RSA signature "
469 "scheme; disabling use of RSA keys", remote_version);
472 chop(server_version_string);
473 debug("Local version string %.200s", server_version_string);
475 if (remote_major != 2 &&
476 !(remote_major == 1 && remote_minor == 99)) {
477 s = "Protocol major versions differ.\n";
478 (void) atomicio(vwrite, sock_out, s, strlen(s));
481 logit("Protocol major versions differ for %s port %d: "
483 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
484 server_version_string, client_version_string);
489 /* Destroy the host and server keys. They will no longer be needed. */
491 destroy_sensitive_data(void)
495 for (i = 0; i < options.num_host_key_files; i++) {
496 if (sensitive_data.host_keys[i]) {
497 key_free(sensitive_data.host_keys[i]);
498 sensitive_data.host_keys[i] = NULL;
500 if (sensitive_data.host_certificates[i]) {
501 key_free(sensitive_data.host_certificates[i]);
502 sensitive_data.host_certificates[i] = NULL;
507 /* Demote private to public keys for network child */
509 demote_sensitive_data(void)
514 for (i = 0; i < options.num_host_key_files; i++) {
515 if (sensitive_data.host_keys[i]) {
516 tmp = key_demote(sensitive_data.host_keys[i]);
517 key_free(sensitive_data.host_keys[i]);
518 sensitive_data.host_keys[i] = tmp;
520 /* Certs do not need demotion */
532 arc4random_stir(); /* noop on recent arc4random() implementations */
533 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
536 RAND_seed(rnd, sizeof(rnd));
537 /* give libcrypto a chance to notice the PID change */
538 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
539 fatal("%s: RAND_bytes failed", __func__);
542 explicit_bzero(rnd, sizeof(rnd));
546 privsep_preauth_child(void)
550 /* Enable challenge-response authentication for privilege separation */
551 privsep_challenge_enable();
554 /* Cache supported mechanism OIDs for later use */
555 if (options.gss_authentication)
556 ssh_gssapi_prepare_supported_oids();
561 /* Demote the private keys to public keys. */
562 demote_sensitive_data();
564 /* Demote the child */
565 if (privsep_chroot) {
566 /* Change our root directory */
567 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
568 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
570 if (chdir("/") == -1)
571 fatal("chdir(\"/\"): %s", strerror(errno));
573 /* Drop our privileges */
574 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
575 (u_int)privsep_pw->pw_gid);
576 gidset[0] = privsep_pw->pw_gid;
577 if (setgroups(1, gidset) < 0)
578 fatal("setgroups: %.100s", strerror(errno));
579 permanently_set_uid(privsep_pw);
584 privsep_preauth(Authctxt *authctxt)
588 struct ssh_sandbox *box = NULL;
590 /* Set up unprivileged child process to deal with network data */
591 pmonitor = monitor_init();
592 /* Store a pointer to the kex for later rekeying */
593 pmonitor->m_pkex = &active_state->kex;
595 if (use_privsep == PRIVSEP_ON)
596 box = ssh_sandbox_init(pmonitor);
599 fatal("fork of unprivileged child failed");
600 } else if (pid != 0) {
601 debug2("Network child is on pid %ld", (long)pid);
603 pmonitor->m_pid = pid;
605 r = ssh_get_authentication_socket(&auth_sock);
607 error("Could not get agent socket: %s",
613 ssh_sandbox_parent_preauth(box, pid);
614 monitor_child_preauth(authctxt, pmonitor);
616 /* Wait for the child's exit status */
617 while (waitpid(pid, &status, 0) < 0) {
620 pmonitor->m_pid = -1;
621 fatal("%s: waitpid: %s", __func__, strerror(errno));
623 privsep_is_preauth = 0;
624 pmonitor->m_pid = -1;
625 if (WIFEXITED(status)) {
626 if (WEXITSTATUS(status) != 0)
627 fatal("%s: preauth child exited with status %d",
628 __func__, WEXITSTATUS(status));
629 } else if (WIFSIGNALED(status))
630 fatal("%s: preauth child terminated by signal %d",
631 __func__, WTERMSIG(status));
633 ssh_sandbox_parent_finish(box);
637 close(pmonitor->m_sendfd);
638 close(pmonitor->m_log_recvfd);
640 /* Arrange for logging to be sent to the monitor */
641 set_log_handler(mm_log_handler, pmonitor);
643 privsep_preauth_child();
644 setproctitle("%s", "[net]");
646 ssh_sandbox_child(box);
653 privsep_postauth(Authctxt *authctxt)
655 #ifdef DISABLE_FD_PASSING
658 if (authctxt->pw->pw_uid == 0) {
660 /* File descriptor passing is broken or root login */
665 /* New socket pair */
666 monitor_reinit(pmonitor);
668 pmonitor->m_pid = fork();
669 if (pmonitor->m_pid == -1)
670 fatal("fork of unprivileged child failed");
671 else if (pmonitor->m_pid != 0) {
672 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
673 buffer_clear(&loginmsg);
674 monitor_clear_keystate(pmonitor);
675 monitor_child_postauth(pmonitor);
683 close(pmonitor->m_sendfd);
684 pmonitor->m_sendfd = -1;
686 /* Demote the private keys to public keys. */
687 demote_sensitive_data();
691 /* Drop privileges */
692 do_setusercontext(authctxt->pw);
695 /* It is safe now to apply the key state */
696 monitor_apply_keystate(pmonitor);
699 * Tell the packet layer that authentication was successful, since
700 * this information is not part of the key state.
702 packet_set_authenticated();
706 list_hostkey_types(void)
715 for (i = 0; i < options.num_host_key_files; i++) {
716 key = sensitive_data.host_keys[i];
718 key = sensitive_data.host_pubkeys[i];
721 /* Check that the key is accepted in HostkeyAlgorithms */
722 if (match_pattern_list(sshkey_ssh_name(key),
723 options.hostkeyalgorithms, 0) != 1) {
724 debug3("%s: %s key not permitted by HostkeyAlgorithms",
725 __func__, sshkey_ssh_name(key));
734 if (buffer_len(&b) > 0)
735 buffer_append(&b, ",", 1);
736 p = key_ssh_name(key);
737 buffer_append(&b, p, strlen(p));
739 /* for RSA we also support SHA2 signatures */
740 if (key->type == KEY_RSA) {
741 p = ",rsa-sha2-512,rsa-sha2-256";
742 buffer_append(&b, p, strlen(p));
746 /* If the private key has a cert peer, then list that too */
747 key = sensitive_data.host_certificates[i];
754 case KEY_ED25519_CERT:
756 if (buffer_len(&b) > 0)
757 buffer_append(&b, ",", 1);
758 p = key_ssh_name(key);
759 buffer_append(&b, p, strlen(p));
763 if ((ret = sshbuf_dup_string(&b)) == NULL)
764 fatal("%s: sshbuf_dup_string failed", __func__);
766 debug("list_hostkey_types: %s", ret);
770 static struct sshkey *
771 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
776 for (i = 0; i < options.num_host_key_files; i++) {
781 case KEY_ED25519_CERT:
783 key = sensitive_data.host_certificates[i];
786 key = sensitive_data.host_keys[i];
787 if (key == NULL && !need_private)
788 key = sensitive_data.host_pubkeys[i];
791 if (key != NULL && key->type == type &&
792 (key->type != KEY_ECDSA || key->ecdsa_nid == nid))
793 return need_private ?
794 sensitive_data.host_keys[i] : key;
800 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
802 return get_hostkey_by_type(type, nid, 0, ssh);
806 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
808 return get_hostkey_by_type(type, nid, 1, ssh);
812 get_hostkey_by_index(int ind)
814 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
816 return (sensitive_data.host_keys[ind]);
820 get_hostkey_public_by_index(int ind, struct ssh *ssh)
822 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
824 return (sensitive_data.host_pubkeys[ind]);
828 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
832 for (i = 0; i < options.num_host_key_files; i++) {
833 if (key_is_cert(key)) {
834 if (key == sensitive_data.host_certificates[i] ||
835 (compare && sensitive_data.host_certificates[i] &&
837 sensitive_data.host_certificates[i])))
840 if (key == sensitive_data.host_keys[i] ||
841 (compare && sensitive_data.host_keys[i] &&
842 sshkey_equal(key, sensitive_data.host_keys[i])))
844 if (key == sensitive_data.host_pubkeys[i] ||
845 (compare && sensitive_data.host_pubkeys[i] &&
846 sshkey_equal(key, sensitive_data.host_pubkeys[i])))
853 /* Inform the client of all hostkeys */
855 notify_hostkeys(struct ssh *ssh)
863 /* Some clients cannot cope with the hostkeys message, skip those. */
864 if (datafellows & SSH_BUG_HOSTKEYS)
867 if ((buf = sshbuf_new()) == NULL)
868 fatal("%s: sshbuf_new", __func__);
869 for (i = nkeys = 0; i < options.num_host_key_files; i++) {
870 key = get_hostkey_public_by_index(i, ssh);
871 if (key == NULL || key->type == KEY_UNSPEC ||
874 fp = sshkey_fingerprint(key, options.fingerprint_hash,
876 debug3("%s: key %d: %s %s", __func__, i,
877 sshkey_ssh_name(key), fp);
880 packet_start(SSH2_MSG_GLOBAL_REQUEST);
881 packet_put_cstring("hostkeys-00@openssh.com");
882 packet_put_char(0); /* want-reply */
885 if ((r = sshkey_putb(key, buf)) != 0)
886 fatal("%s: couldn't put hostkey %d: %s",
887 __func__, i, ssh_err(r));
888 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf));
891 debug3("%s: sent %u hostkeys", __func__, nkeys);
893 fatal("%s: no hostkeys", __func__);
899 * returns 1 if connection should be dropped, 0 otherwise.
900 * dropping starts at connection #max_startups_begin with a probability
901 * of (max_startups_rate/100). the probability increases linearly until
902 * all connections are dropped for startups > max_startups
905 drop_connection(int startups)
909 if (startups < options.max_startups_begin)
911 if (startups >= options.max_startups)
913 if (options.max_startups_rate == 100)
916 p = 100 - options.max_startups_rate;
917 p *= startups - options.max_startups_begin;
918 p /= options.max_startups - options.max_startups_begin;
919 p += options.max_startups_rate;
920 r = arc4random_uniform(100);
922 debug("drop_connection: p %d, r %d", p, r);
923 return (r < p) ? 1 : 0;
929 if (options.version_addendum && *options.version_addendum != '\0')
930 fprintf(stderr, "%s %s, %s\n",
932 options.version_addendum, OPENSSL_VERSION);
934 fprintf(stderr, "%s, %s\n",
935 SSH_RELEASE, OPENSSL_VERSION);
937 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n"
938 " [-E log_file] [-f config_file] [-g login_grace_time]\n"
939 " [-h host_key_file] [-o option] [-p port] [-u len]\n"
945 send_rexec_state(int fd, struct sshbuf *conf)
950 debug3("%s: entering fd = %d config len %zu", __func__, fd,
954 * Protocol from reexec master to child:
955 * string configuration
956 * string rngseed (only if OpenSSL is not self-seeded)
958 if ((m = sshbuf_new()) == NULL)
959 fatal("%s: sshbuf_new failed", __func__);
960 if ((r = sshbuf_put_stringb(m, conf)) != 0)
961 fatal("%s: buffer error: %s", __func__, ssh_err(r));
963 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
964 rexec_send_rng_seed(m);
967 if (ssh_msg_send(fd, 0, m) == -1)
968 fatal("%s: ssh_msg_send failed", __func__);
972 debug3("%s: done", __func__);
976 recv_rexec_state(int fd, Buffer *conf)
982 debug3("%s: entering fd = %d", __func__, fd);
986 if (ssh_msg_recv(fd, &m) == -1)
987 fatal("%s: ssh_msg_recv failed", __func__);
988 if (buffer_get_char(&m) != 0)
989 fatal("%s: rexec version mismatch", __func__);
991 cp = buffer_get_string(&m, &len);
993 buffer_append(conf, cp, len);
996 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
997 rexec_recv_rng_seed(&m);
1002 debug3("%s: done", __func__);
1005 /* Accept a connection from inetd */
1007 server_accept_inetd(int *sock_in, int *sock_out)
1013 close(REEXEC_CONFIG_PASS_FD);
1014 *sock_in = *sock_out = dup(STDIN_FILENO);
1016 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1017 close(REEXEC_STARTUP_PIPE_FD);
1020 *sock_in = dup(STDIN_FILENO);
1021 *sock_out = dup(STDOUT_FILENO);
1024 * We intentionally do not close the descriptors 0, 1, and 2
1025 * as our code for setting the descriptors won't work if
1026 * ttyfd happens to be one of those.
1028 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1029 dup2(fd, STDIN_FILENO);
1030 dup2(fd, STDOUT_FILENO);
1032 dup2(fd, STDERR_FILENO);
1033 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO))
1036 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1040 * Listen for TCP connections
1043 listen_on_addrs(struct listenaddr *la)
1045 int ret, listen_sock;
1046 struct addrinfo *ai;
1047 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1051 for (ai = la->addrs; ai; ai = ai->ai_next) {
1052 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1054 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1055 fatal("Too many listen sockets. "
1056 "Enlarge MAX_LISTEN_SOCKS");
1057 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1058 ntop, sizeof(ntop), strport, sizeof(strport),
1059 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1060 error("getnameinfo failed: %.100s",
1061 ssh_gai_strerror(ret));
1064 /* Create socket for listening. */
1065 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1067 if (listen_sock < 0) {
1068 /* kernel may not support ipv6 */
1069 verbose("socket: %.100s", strerror(errno));
1072 if (set_nonblock(listen_sock) == -1) {
1076 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
1077 verbose("socket: CLOEXEC: %s", strerror(errno));
1081 /* Socket options */
1082 set_reuseaddr(listen_sock);
1083 if (la->rdomain != NULL &&
1084 set_rdomain(listen_sock, la->rdomain) == -1) {
1089 /* Only communicate in IPv6 over AF_INET6 sockets. */
1090 if (ai->ai_family == AF_INET6)
1091 sock_set_v6only(listen_sock);
1093 debug("Bind to port %s on %s.", strport, ntop);
1095 len = sizeof(socksize);
1096 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len);
1097 debug("Server TCP RWIN socket size: %d", socksize);
1099 /* Bind the socket to the desired port. */
1100 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1101 error("Bind to port %s on %s failed: %.200s.",
1102 strport, ntop, strerror(errno));
1106 listen_socks[num_listen_socks] = listen_sock;
1109 /* Start listening on the port. */
1110 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1111 fatal("listen on [%s]:%s: %.100s",
1112 ntop, strport, strerror(errno));
1113 logit("Server listening on %s port %s%s%s.",
1115 la->rdomain == NULL ? "" : " rdomain ",
1116 la->rdomain == NULL ? "" : la->rdomain);
1125 for (i = 0; i < options.num_listen_addrs; i++) {
1126 listen_on_addrs(&options.listen_addrs[i]);
1127 freeaddrinfo(options.listen_addrs[i].addrs);
1128 free(options.listen_addrs[i].rdomain);
1129 memset(&options.listen_addrs[i], 0,
1130 sizeof(options.listen_addrs[i]));
1132 free(options.listen_addrs);
1133 options.listen_addrs = NULL;
1134 options.num_listen_addrs = 0;
1136 if (!num_listen_socks)
1137 fatal("Cannot bind any address.");
1141 * The main TCP accept loop. Note that, for the non-debug case, returns
1142 * from this function are in a forked subprocess.
1145 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1148 int i, j, ret, maxfd;
1150 int startup_p[2] = { -1 , -1 };
1151 struct sockaddr_storage from;
1156 /* setup fd set for accept */
1159 for (i = 0; i < num_listen_socks; i++)
1160 if (listen_socks[i] > maxfd)
1161 maxfd = listen_socks[i];
1162 /* pipes connected to unauthenticated childs */
1163 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1164 for (i = 0; i < options.max_startups; i++)
1165 startup_pipes[i] = -1;
1168 * Stay listening for connections until the system crashes or
1169 * the daemon is killed with a signal.
1172 if (received_sighup)
1175 fdset = xcalloc(howmany(maxfd + 1, NFDBITS),
1178 for (i = 0; i < num_listen_socks; i++)
1179 FD_SET(listen_socks[i], fdset);
1180 for (i = 0; i < options.max_startups; i++)
1181 if (startup_pipes[i] != -1)
1182 FD_SET(startup_pipes[i], fdset);
1184 /* Wait in select until there is a connection. */
1185 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1186 if (ret < 0 && errno != EINTR)
1187 error("select: %.100s", strerror(errno));
1188 if (received_sigterm) {
1189 logit("Received signal %d; terminating.",
1190 (int) received_sigterm);
1191 close_listen_socks();
1192 if (options.pid_file != NULL)
1193 unlink(options.pid_file);
1194 exit(received_sigterm == SIGTERM ? 0 : 255);
1199 for (i = 0; i < options.max_startups; i++)
1200 if (startup_pipes[i] != -1 &&
1201 FD_ISSET(startup_pipes[i], fdset)) {
1203 * the read end of the pipe is ready
1204 * if the child has closed the pipe
1205 * after successful authentication
1206 * or if the child has died
1208 close(startup_pipes[i]);
1209 startup_pipes[i] = -1;
1212 for (i = 0; i < num_listen_socks; i++) {
1213 if (!FD_ISSET(listen_socks[i], fdset))
1215 fromlen = sizeof(from);
1216 *newsock = accept(listen_socks[i],
1217 (struct sockaddr *)&from, &fromlen);
1219 if (errno != EINTR && errno != EWOULDBLOCK &&
1220 errno != ECONNABORTED && errno != EAGAIN)
1221 error("accept: %.100s",
1223 if (errno == EMFILE || errno == ENFILE)
1227 if (unset_nonblock(*newsock) == -1) {
1231 if (drop_connection(startups) == 1) {
1232 char *laddr = get_local_ipaddr(*newsock);
1233 char *raddr = get_peer_ipaddr(*newsock);
1235 verbose("drop connection #%d from [%s]:%d "
1236 "on [%s]:%d past MaxStartups", startups,
1237 raddr, get_peer_port(*newsock),
1238 laddr, get_local_port(*newsock));
1244 if (pipe(startup_p) == -1) {
1249 if (rexec_flag && socketpair(AF_UNIX,
1250 SOCK_STREAM, 0, config_s) == -1) {
1251 error("reexec socketpair: %s",
1254 close(startup_p[0]);
1255 close(startup_p[1]);
1259 for (j = 0; j < options.max_startups; j++)
1260 if (startup_pipes[j] == -1) {
1261 startup_pipes[j] = startup_p[0];
1262 if (maxfd < startup_p[0])
1263 maxfd = startup_p[0];
1269 * Got connection. Fork a child to handle it, unless
1270 * we are in debugging mode.
1274 * In debugging mode. Close the listening
1275 * socket, and start processing the
1276 * connection without forking.
1278 debug("Server will not fork when running in debugging mode.");
1279 close_listen_socks();
1280 *sock_in = *newsock;
1281 *sock_out = *newsock;
1282 close(startup_p[0]);
1283 close(startup_p[1]);
1287 send_rexec_state(config_s[0],
1295 * Normal production daemon. Fork, and have
1296 * the child process the connection. The
1297 * parent continues listening.
1299 platform_pre_fork();
1300 if ((pid = fork()) == 0) {
1302 * Child. Close the listening and
1303 * max_startup sockets. Start using
1304 * the accepted socket. Reinitialize
1305 * logging (since our pid has changed).
1306 * We break out of the loop to handle
1309 platform_post_fork_child();
1310 startup_pipe = startup_p[1];
1311 close_startup_pipes();
1312 close_listen_socks();
1313 *sock_in = *newsock;
1314 *sock_out = *newsock;
1315 log_init(__progname,
1317 options.log_facility,
1324 /* Parent. Stay in the loop. */
1325 platform_post_fork_parent(pid);
1327 error("fork: %.100s", strerror(errno));
1329 debug("Forked child %ld.", (long)pid);
1331 close(startup_p[1]);
1334 send_rexec_state(config_s[0], &cfg);
1341 * Ensure that our random state differs
1342 * from that of the child
1345 arc4random_buf(rnd, sizeof(rnd));
1347 RAND_seed(rnd, sizeof(rnd));
1348 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
1349 fatal("%s: RAND_bytes failed", __func__);
1351 explicit_bzero(rnd, sizeof(rnd));
1354 /* child process check (or debug mode) */
1355 if (num_listen_socks < 0)
1361 * If IP options are supported, make sure there are none (log and
1362 * return an error if any are found). Basically we are worried about
1363 * source routing; it can be used to pretend you are somebody
1364 * (ip-address) you are not. That itself may be "almost acceptable"
1365 * under certain circumstances, but rhosts autentication is useless
1366 * if source routing is accepted. Notice also that if we just dropped
1367 * source routing here, the other side could use IP spoofing to do
1368 * rest of the interaction and could still bypass security. So we
1369 * exit here if we detect any IP options.
1372 check_ip_options(struct ssh *ssh)
1375 int sock_in = ssh_packet_get_connection_in(ssh);
1376 struct sockaddr_storage from;
1378 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
1379 char text[sizeof(opts) * 3 + 1];
1381 memset(&from, 0, sizeof(from));
1382 if (getpeername(sock_in, (struct sockaddr *)&from,
1385 if (from.ss_family != AF_INET)
1387 /* XXX IPv6 options? */
1389 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
1390 &option_size) >= 0 && option_size != 0) {
1392 for (i = 0; i < option_size; i++)
1393 snprintf(text + i*3, sizeof(text) - i*3,
1395 fatal("Connection from %.100s port %d with IP opts: %.800s",
1396 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
1399 #endif /* IP_OPTIONS */
1402 /* Set the routing domain for this process */
1404 set_process_rdomain(struct ssh *ssh, const char *name)
1406 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN)
1408 return; /* default */
1410 if (strcmp(name, "%D") == 0) {
1411 /* "expands" to routing domain of connection */
1412 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
1415 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */
1416 return sys_set_process_rdomain(name);
1417 #elif defined(__OpenBSD__)
1418 int rtable, ortable = getrtable();
1422 return; /* default */
1424 if (strcmp(name, "%D") == 0) {
1425 /* "expands" to routing domain of connection */
1426 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
1430 rtable = (int)strtonum(name, 0, 255, &errstr);
1431 if (errstr != NULL) /* Shouldn't happen */
1432 fatal("Invalid routing domain \"%s\": %s", name, errstr);
1433 if (rtable != ortable && setrtable(rtable) != 0)
1434 fatal("Unable to set routing domain %d: %s",
1435 rtable, strerror(errno));
1436 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable);
1437 #else /* defined(__OpenBSD__) */
1438 fatal("Unable to set routing domain: not supported in this platform");
1443 * Main program for the daemon.
1446 main(int ac, char **av)
1448 struct ssh *ssh = NULL;
1449 extern char *optarg;
1451 int r, opt, on = 1, already_daemon, remote_port;
1452 int sock_in = -1, sock_out = -1, newsock = -1;
1453 const char *remote_ip, *rdomain;
1454 char *fp, *line, *laddr, *logfile = NULL;
1455 int config_s[2] = { -1 , -1 };
1457 u_int64_t ibytes, obytes;
1460 struct sshkey *pubkey;
1463 struct connection_info *connection_info = NULL;
1465 ssh_malloc_init(); /* must be called before any mallocs */
1467 #ifdef HAVE_SECUREWARE
1468 (void)set_auth_parameters(ac, av);
1470 __progname = ssh_get_progname(av[0]);
1472 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1475 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1476 for (i = 0; (int)i < ac; i++)
1477 saved_argv[i] = xstrdup(av[i]);
1478 saved_argv[i] = NULL;
1480 #ifndef HAVE_SETPROCTITLE
1481 /* Prepare for later setproctitle emulation */
1482 compat_init_setproctitle(ac, av);
1486 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1487 debug("setgroups(): %.200s", strerror(errno));
1489 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1492 /* Initialize configuration options to their default values. */
1493 initialize_server_options(&options);
1495 /* Parse command-line arguments. */
1496 while ((opt = getopt(ac, av,
1497 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) {
1500 options.address_family = AF_INET;
1503 options.address_family = AF_INET6;
1506 config_file_name = optarg;
1509 servconf_add_hostcert("[command-line]", 0,
1513 if (debug_flag == 0) {
1515 options.log_level = SYSLOG_LEVEL_DEBUG1;
1516 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1517 options.log_level++;
1542 options.log_level = SYSLOG_LEVEL_QUIET;
1545 /* protocol 1, ignored */
1548 options.ports_from_cmdline = 1;
1549 if (options.num_ports >= MAX_PORTS) {
1550 fprintf(stderr, "too many ports.\n");
1553 options.ports[options.num_ports++] = a2port(optarg);
1554 if (options.ports[options.num_ports-1] <= 0) {
1555 fprintf(stderr, "Bad port number.\n");
1560 if ((options.login_grace_time = convtime(optarg)) == -1) {
1561 fprintf(stderr, "Invalid login grace time.\n");
1566 /* protocol 1, ignored */
1569 servconf_add_hostkey("[command-line]", 0,
1579 connection_info = get_connection_info(0, 0);
1580 if (parse_server_match_testspec(connection_info,
1585 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1586 if (utmp_len > HOST_NAME_MAX+1) {
1587 fprintf(stderr, "Invalid utmp length.\n");
1592 line = xstrdup(optarg);
1593 if (process_server_config_line(&options, line,
1594 "command-line", 0, NULL, NULL) != 0)
1604 if (rexeced_flag || inetd_flag)
1606 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1607 fatal("sshd re-exec requires execution with an absolute path");
1609 closefrom(REEXEC_MIN_FREE_FD);
1611 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1614 OpenSSL_add_all_algorithms();
1617 /* If requested, redirect the logs to the specified logfile. */
1618 if (logfile != NULL)
1619 log_redirect_stderr_to(logfile);
1621 * Force logging to stderr until we have loaded the private host
1622 * key (unless started from inetd)
1624 log_init(__progname,
1625 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1626 SYSLOG_LEVEL_INFO : options.log_level,
1627 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1628 SYSLOG_FACILITY_AUTH : options.log_facility,
1629 log_stderr || !inetd_flag);
1632 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1633 * root's environment
1635 if (getenv("KRB5CCNAME") != NULL)
1636 (void) unsetenv("KRB5CCNAME");
1638 sensitive_data.have_ssh2_key = 0;
1641 * If we're not doing an extended test do not silently ignore connection
1644 if (test_flag < 2 && connection_info != NULL)
1645 fatal("Config test connection parameter (-C) provided without "
1648 /* Fetch our configuration */
1651 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1652 else if (strcasecmp(config_file_name, "none") != 0)
1653 load_server_config(config_file_name, &cfg);
1655 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1660 /* Fill in default values for those options not explicitly set. */
1661 fill_default_server_options(&options);
1663 /* challenge-response is implemented via keyboard interactive */
1664 if (options.challenge_response_authentication)
1665 options.kbd_interactive_authentication = 1;
1667 /* Check that options are sensible */
1668 if (options.authorized_keys_command_user == NULL &&
1669 (options.authorized_keys_command != NULL &&
1670 strcasecmp(options.authorized_keys_command, "none") != 0))
1671 fatal("AuthorizedKeysCommand set without "
1672 "AuthorizedKeysCommandUser");
1673 if (options.authorized_principals_command_user == NULL &&
1674 (options.authorized_principals_command != NULL &&
1675 strcasecmp(options.authorized_principals_command, "none") != 0))
1676 fatal("AuthorizedPrincipalsCommand set without "
1677 "AuthorizedPrincipalsCommandUser");
1680 * Check whether there is any path through configured auth methods.
1681 * Unfortunately it is not possible to verify this generally before
1682 * daemonisation in the presence of Match block, but this catches
1683 * and warns for trivial misconfigurations that could break login.
1685 if (options.num_auth_methods != 0) {
1686 for (i = 0; i < options.num_auth_methods; i++) {
1687 if (auth2_methods_valid(options.auth_methods[i],
1691 if (i >= options.num_auth_methods)
1692 fatal("AuthenticationMethods cannot be satisfied by "
1693 "enabled authentication methods");
1696 /* Check that there are no remaining arguments. */
1698 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1702 debug("sshd version %s, %s", SSH_VERSION,
1704 SSLeay_version(SSLEAY_VERSION)
1710 /* Store privilege separation user for later use if required. */
1711 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0);
1712 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1713 if (privsep_chroot || options.kerberos_authentication)
1714 fatal("Privilege separation user %s does not exist",
1717 privsep_pw = pwcopy(privsep_pw);
1718 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd));
1719 privsep_pw->pw_passwd = xstrdup("*");
1723 /* load host keys */
1724 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1725 sizeof(struct sshkey *));
1726 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1727 sizeof(struct sshkey *));
1729 if (options.host_key_agent) {
1730 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1731 setenv(SSH_AUTHSOCKET_ENV_NAME,
1732 options.host_key_agent, 1);
1733 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1736 error("Could not connect to agent \"%s\": %s",
1737 options.host_key_agent, ssh_err(r));
1740 for (i = 0; i < options.num_host_key_files; i++) {
1741 if (options.host_key_files[i] == NULL)
1743 key = key_load_private(options.host_key_files[i], "", NULL);
1744 pubkey = key_load_public(options.host_key_files[i], NULL);
1746 if (pubkey == NULL && key != NULL)
1747 pubkey = key_demote(key);
1748 sensitive_data.host_keys[i] = key;
1749 sensitive_data.host_pubkeys[i] = pubkey;
1751 if (key == NULL && pubkey != NULL && have_agent) {
1752 debug("will rely on agent for hostkey %s",
1753 options.host_key_files[i]);
1754 keytype = pubkey->type;
1755 } else if (key != NULL) {
1756 keytype = key->type;
1758 error("Could not load host key: %s",
1759 options.host_key_files[i]);
1760 sensitive_data.host_keys[i] = NULL;
1761 sensitive_data.host_pubkeys[i] = NULL;
1771 if (have_agent || key != NULL)
1772 sensitive_data.have_ssh2_key = 1;
1775 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
1776 SSH_FP_DEFAULT)) == NULL)
1777 fatal("sshkey_fingerprint failed");
1778 debug("%s host key #%d: %s %s",
1779 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
1782 if (!sensitive_data.have_ssh2_key) {
1783 logit("sshd: no hostkeys available -- exiting.");
1788 * Load certificates. They are stored in an array at identical
1789 * indices to the public keys that they relate to.
1791 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1792 sizeof(struct sshkey *));
1793 for (i = 0; i < options.num_host_key_files; i++)
1794 sensitive_data.host_certificates[i] = NULL;
1796 for (i = 0; i < options.num_host_cert_files; i++) {
1797 if (options.host_cert_files[i] == NULL)
1799 key = key_load_public(options.host_cert_files[i], NULL);
1801 error("Could not load host certificate: %s",
1802 options.host_cert_files[i]);
1805 if (!key_is_cert(key)) {
1806 error("Certificate file is not a certificate: %s",
1807 options.host_cert_files[i]);
1811 /* Find matching private key */
1812 for (j = 0; j < options.num_host_key_files; j++) {
1813 if (key_equal_public(key,
1814 sensitive_data.host_keys[j])) {
1815 sensitive_data.host_certificates[j] = key;
1819 if (j >= options.num_host_key_files) {
1820 error("No matching private key for certificate: %s",
1821 options.host_cert_files[i]);
1825 sensitive_data.host_certificates[j] = key;
1826 debug("host certificate: #%u type %d %s", j, key->type,
1830 if (privsep_chroot) {
1833 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1834 (S_ISDIR(st.st_mode) == 0))
1835 fatal("Missing privilege separation directory: %s",
1836 _PATH_PRIVSEP_CHROOT_DIR);
1839 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1840 (st.st_uid != getuid () ||
1841 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1843 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1845 fatal("%s must be owned by root and not group or "
1846 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1849 if (test_flag > 1) {
1851 * If no connection info was provided by -C then use
1852 * use a blank one that will cause no predicate to match.
1854 if (connection_info == NULL)
1855 connection_info = get_connection_info(0, 0);
1856 parse_server_match_config(&options, connection_info);
1857 dump_config(&options);
1860 /* Configuration looks good, so exit if in test mode. */
1865 * Clear out any supplemental groups we may have inherited. This
1866 * prevents inadvertent creation of files with bad modes (in the
1867 * portable version at least, it's certainly possible for PAM
1868 * to create a file, and we can't control the code in every
1869 * module which might be used).
1871 if (setgroups(0, NULL) < 0)
1872 debug("setgroups() failed: %.200s", strerror(errno));
1876 fatal("rexec_argc %d < 0", rexec_argc);
1877 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1878 for (i = 0; i < (u_int)rexec_argc; i++) {
1879 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1880 rexec_argv[i] = saved_argv[i];
1882 rexec_argv[rexec_argc] = "-R";
1883 rexec_argv[rexec_argc + 1] = NULL;
1886 /* Ensure that umask disallows at least group and world write */
1887 new_umask = umask(0077) | 0022;
1888 (void) umask(new_umask);
1890 /* Initialize the log (it is reinitialized below in case we forked). */
1891 if (debug_flag && (!inetd_flag || rexeced_flag))
1893 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1896 * If not in debugging mode, not started from inetd and not already
1897 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
1898 * terminal, and fork. The original process exits.
1900 already_daemon = daemonized();
1901 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
1903 if (daemon(0, 0) < 0)
1904 fatal("daemon() failed: %.200s", strerror(errno));
1906 disconnect_controlling_tty();
1908 /* Reinitialize the log (because of the fork above). */
1909 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1911 /* Avoid killing the process in high-pressure swapping environments. */
1912 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0)
1913 debug("madvise(): %.200s", strerror(errno));
1915 /* Chdir to the root directory so that the current disk can be
1916 unmounted if desired. */
1917 if (chdir("/") == -1)
1918 error("chdir(\"/\"): %s", strerror(errno));
1920 /* ignore SIGPIPE */
1921 signal(SIGPIPE, SIG_IGN);
1923 /* Get a connection, either from inetd or a listening TCP socket */
1925 server_accept_inetd(&sock_in, &sock_out);
1927 platform_pre_listen();
1930 signal(SIGHUP, sighup_handler);
1931 signal(SIGCHLD, main_sigchld_handler);
1932 signal(SIGTERM, sigterm_handler);
1933 signal(SIGQUIT, sigterm_handler);
1936 * Write out the pid file after the sigterm handler
1937 * is setup and the listen sockets are bound
1939 if (options.pid_file != NULL && !debug_flag) {
1940 FILE *f = fopen(options.pid_file, "w");
1943 error("Couldn't create pid file \"%s\": %s",
1944 options.pid_file, strerror(errno));
1946 fprintf(f, "%ld\n", (long) getpid());
1951 /* Accept a connection and return in a forked child */
1952 server_accept_loop(&sock_in, &sock_out,
1953 &newsock, config_s);
1956 /* This is the child processing a new connection. */
1957 setproctitle("%s", "[accepted]");
1960 * Create a new session and process group since the 4.4BSD
1961 * setlogin() affects the entire process group. We don't
1962 * want the child to be able to affect the parent.
1964 #if !defined(SSHD_ACQUIRES_CTTY)
1966 * If setsid is called, on some platforms sshd will later acquire a
1967 * controlling terminal which will result in "could not set
1968 * controlling tty" errors.
1970 if (!debug_flag && !inetd_flag && setsid() < 0)
1971 error("setsid: %.100s", strerror(errno));
1977 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1978 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1979 dup2(newsock, STDIN_FILENO);
1980 dup2(STDIN_FILENO, STDOUT_FILENO);
1981 if (startup_pipe == -1)
1982 close(REEXEC_STARTUP_PIPE_FD);
1983 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
1984 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1985 close(startup_pipe);
1986 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1989 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1992 execv(rexec_argv[0], rexec_argv);
1994 /* Reexec has failed, fall back and continue */
1995 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1996 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1997 log_init(__progname, options.log_level,
1998 options.log_facility, log_stderr);
2001 close(REEXEC_CONFIG_PASS_FD);
2002 newsock = sock_out = sock_in = dup(STDIN_FILENO);
2003 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
2004 dup2(fd, STDIN_FILENO);
2005 dup2(fd, STDOUT_FILENO);
2006 if (fd > STDERR_FILENO)
2009 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
2010 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2013 /* Executed child processes don't need these. */
2014 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
2015 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
2018 * Disable the key regeneration alarm. We will not regenerate the
2019 * key since we are no longer in a position to give it to anyone. We
2020 * will not restart on SIGHUP since it no longer makes sense.
2023 signal(SIGALRM, SIG_DFL);
2024 signal(SIGHUP, SIG_DFL);
2025 signal(SIGTERM, SIG_DFL);
2026 signal(SIGQUIT, SIG_DFL);
2027 signal(SIGCHLD, SIG_DFL);
2028 signal(SIGINT, SIG_DFL);
2032 * Initialize the resolver. This may not happen automatically
2033 * before privsep chroot().
2035 if ((_res.options & RES_INIT) == 0) {
2036 debug("res_init()");
2041 * Force GSS-API to parse its configuration and load any
2042 * mechanism plugins.
2046 OM_uint32 minor_status;
2047 gss_indicate_mechs(&minor_status, &mechs);
2048 gss_release_oid_set(&minor_status, &mechs);
2054 * Register our connection. This turns encryption off because we do
2057 packet_set_connection(sock_in, sock_out);
2058 packet_set_server();
2059 ssh = active_state; /* XXX */
2061 check_ip_options(ssh);
2063 /* Prepare the channels layer */
2064 channel_init_channels(ssh);
2065 channel_set_af(ssh, options.address_family);
2066 process_permitopen(ssh, &options);
2068 /* Set SO_KEEPALIVE if requested. */
2069 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
2070 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
2071 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
2073 if ((remote_port = ssh_remote_port(ssh)) < 0) {
2074 debug("ssh_remote_port failed");
2078 if (options.routing_domain != NULL)
2079 set_process_rdomain(ssh, options.routing_domain);
2082 * The rest of the code depends on the fact that
2083 * ssh_remote_ipaddr() caches the remote ip, even if
2084 * the socket goes away.
2086 remote_ip = ssh_remote_ipaddr(ssh);
2088 #ifdef SSH_AUDIT_EVENTS
2089 audit_connection_from(remote_ip, remote_port);
2092 allow_severity = options.log_facility|LOG_INFO;
2093 deny_severity = options.log_facility|LOG_WARNING;
2094 /* Check whether logins are denied from this host. */
2095 if (packet_connection_is_on_socket()) {
2096 struct request_info req;
2098 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
2101 if (!hosts_access(&req)) {
2102 debug("Connection refused by tcp wrapper");
2105 fatal("libwrap refuse returns");
2108 #endif /* LIBWRAP */
2110 rdomain = ssh_packet_rdomain_in(ssh);
2112 /* Log the connection. */
2113 laddr = get_local_ipaddr(sock_in);
2114 verbose("Connection from %s port %d on %s port %d%s%s%s",
2115 remote_ip, remote_port, laddr, ssh_local_port(ssh),
2116 rdomain == NULL ? "" : " rdomain \"",
2117 rdomain == NULL ? "" : rdomain,
2118 rdomain == NULL ? "" : "\"");
2122 * We don't want to listen forever unless the other side
2123 * successfully authenticates itself. So we set up an alarm which is
2124 * cleared after successful authentication. A limit of zero
2125 * indicates no limit. Note that we don't set the alarm in debugging
2126 * mode; it is just annoying to have the server exit just when you
2127 * are about to discover the bug.
2129 signal(SIGALRM, grace_alarm_handler);
2131 alarm(options.login_grace_time);
2133 sshd_exchange_identification(ssh, sock_in, sock_out);
2134 packet_set_nonblocking();
2136 /* allocate authentication context */
2137 authctxt = xcalloc(1, sizeof(*authctxt));
2139 authctxt->loginmsg = &loginmsg;
2141 /* XXX global for cleanup, access from other modules */
2142 the_authctxt = authctxt;
2144 /* Set default key authentication options */
2145 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL)
2146 fatal("allocation failed");
2148 /* prepare buffer to collect messages to display to user after login */
2149 buffer_init(&loginmsg);
2155 if (privsep_preauth(authctxt) == 1)
2157 } else if (have_agent) {
2158 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
2159 error("Unable to get agent socket: %s", ssh_err(r));
2164 /* perform the key exchange */
2165 /* authenticate user and start session */
2167 do_authentication2(authctxt);
2170 * If we use privilege separation, the unprivileged child transfers
2171 * the current keystate and exits
2174 mm_send_keystate(pmonitor);
2175 packet_clear_keys();
2181 * Cancel the alarm we set to limit the time taken for
2185 signal(SIGALRM, SIG_DFL);
2186 authctxt->authenticated = 1;
2187 if (startup_pipe != -1) {
2188 close(startup_pipe);
2192 #ifdef SSH_AUDIT_EVENTS
2193 audit_event(SSH_AUTH_SUCCESS);
2197 if (options.gss_authentication) {
2198 temporarily_use_uid(authctxt->pw);
2199 ssh_gssapi_storecreds();
2204 if (options.use_pam) {
2206 do_pam_session(ssh);
2211 * In privilege separation, we fork another child and prepare
2212 * file descriptor passing.
2215 privsep_postauth(authctxt);
2216 /* the monitor process [priv] will not return */
2219 packet_set_timeout(options.client_alive_interval,
2220 options.client_alive_count_max);
2222 /* Try to send all our hostkeys to the client */
2223 notify_hostkeys(ssh);
2225 /* Start session. */
2226 do_authenticated(ssh, authctxt);
2228 /* The connection has been terminated. */
2229 packet_get_bytes(&ibytes, &obytes);
2230 verbose("Transferred: sent %llu, received %llu bytes",
2231 (unsigned long long)obytes, (unsigned long long)ibytes);
2233 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2236 if (options.use_pam)
2238 #endif /* USE_PAM */
2240 #ifdef SSH_AUDIT_EVENTS
2241 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2253 sshd_hostkey_sign(struct sshkey *privkey, struct sshkey *pubkey,
2254 u_char **signature, size_t *slen, const u_char *data, size_t dlen,
2255 const char *alg, u_int flag)
2258 u_int xxx_slen, xxx_dlen = dlen;
2261 if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen,
2263 fatal("%s: key_sign failed", __func__);
2266 } else if (use_privsep) {
2267 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen,
2269 fatal("%s: pubkey_sign failed", __func__);
2273 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen,
2274 data, dlen, alg, datafellows)) != 0)
2275 fatal("%s: ssh_agent_sign failed: %s",
2276 __func__, ssh_err(r));
2281 /* SSH2 key exchange */
2285 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
2289 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
2290 options.kex_algorithms);
2291 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
2293 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
2295 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2296 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2298 if (options.compression == COMP_NONE) {
2299 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2300 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2303 if (options.rekey_limit || options.rekey_interval)
2304 packet_set_rekey_limits(options.rekey_limit,
2305 options.rekey_interval);
2307 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
2308 list_hostkey_types());
2310 /* start key exchange */
2311 if ((r = kex_setup(active_state, myproposal)) != 0)
2312 fatal("kex_setup: %s", ssh_err(r));
2313 kex = active_state->kex;
2315 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2316 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2317 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
2318 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
2319 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
2320 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2321 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2322 # ifdef OPENSSL_HAS_ECC
2323 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2326 kex->kex[KEX_C25519_SHA256] = kexc25519_server;
2328 kex->client_version_string=client_version_string;
2329 kex->server_version_string=server_version_string;
2330 kex->load_host_public_key=&get_hostkey_public_by_type;
2331 kex->load_host_private_key=&get_hostkey_private_by_type;
2332 kex->host_key_index=&get_hostkey_index;
2333 kex->sign = sshd_hostkey_sign;
2335 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done);
2337 session_id2 = kex->session_id;
2338 session_id2_len = kex->session_id_len;
2341 /* send 1st encrypted/maced/compressed message */
2342 packet_start(SSH2_MSG_IGNORE);
2343 packet_put_cstring("markus");
2345 packet_write_wait();
2350 /* server specific fatal cleanup */
2354 struct ssh *ssh = active_state; /* XXX */
2357 do_cleanup(ssh, the_authctxt);
2358 if (use_privsep && privsep_is_preauth &&
2359 pmonitor != NULL && pmonitor->m_pid > 1) {
2360 debug("Killing privsep child %d", pmonitor->m_pid);
2361 if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2363 error("%s: kill(%d): %s", __func__,
2364 pmonitor->m_pid, strerror(errno));
2367 #ifdef SSH_AUDIT_EVENTS
2368 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2369 if (!use_privsep || mm_is_monitor())
2370 audit_event(SSH_CONNECTION_ABANDON);