1 /* $OpenBSD: sshd.c,v 1.492 2017/09/12 06:32:07 djm Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This program is the ssh daemon. It listens for connections from clients,
7 * and performs authentication, executes use commands or shell, and forwards
8 * information to/from the application to the user client over an encrypted
9 * connection. This can also handle forwarding of X11, TCP/IP, and
10 * authentication agent connections.
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
18 * SSH2 implementation:
19 * Privilege Separation:
21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22 * Copyright (c) 2002 Niels Provos. All rights reserved.
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
47 #include <sys/types.h>
48 #include <sys/ioctl.h>
49 #include <sys/socket.h>
50 #ifdef HAVE_SYS_STAT_H
51 # include <sys/stat.h>
53 #ifdef HAVE_SYS_TIME_H
54 # include <sys/time.h>
56 #include "openbsd-compat/sys-tree.h"
57 #include "openbsd-compat/sys-queue.h"
77 #include <openssl/dh.h>
78 #include <openssl/bn.h>
79 #include <openssl/rand.h>
80 #include "openbsd-compat/openssl-compat.h"
83 #ifdef HAVE_SECUREWARE
84 #include <sys/security.h>
104 #include "myproposal.h"
105 #include "authfile.h"
106 #include "pathnames.h"
107 #include "atomicio.h"
108 #include "canohost.h"
109 #include "hostfile.h"
113 #include "dispatch.h"
114 #include "channels.h"
120 #include "monitor_wrap.h"
121 #include "ssh-sandbox.h"
126 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
127 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
128 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
129 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
131 extern char *__progname;
133 /* Server configuration options. */
134 ServerOptions options;
136 /* Name of the server configuration file. */
137 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
140 * Debug mode flag. This can be set on the command line. If debug
141 * mode is enabled, extra debugging output will be sent to the system
142 * log, the daemon will not go to background, and will exit after processing
143 * the first connection.
147 /* Flag indicating that the daemon should only test the configuration and keys. */
150 /* Flag indicating that the daemon is being started from inetd. */
153 /* Flag indicating that sshd should not detach and become a daemon. */
154 int no_daemon_flag = 0;
156 /* debug goes to stderr unless inetd_flag is set */
159 /* Saved arguments to main(). */
164 int rexeced_flag = 0;
170 * The sockets that the server is listening; this is used in the SIGHUP
173 #define MAX_LISTEN_SOCKS 16
174 int listen_socks[MAX_LISTEN_SOCKS];
175 int num_listen_socks = 0;
178 * the client's version string, passed by sshd2 in compat mode. if != NULL,
179 * sshd will skip the version-number exchange
181 char *client_version_string = NULL;
182 char *server_version_string = NULL;
184 /* Daemon's agent connection */
189 * Any really sensitive data in the application is contained in this
190 * structure. The idea is that this structure could be locked into memory so
191 * that the pages do not get written into swap. However, there are some
192 * problems. The private key contains BIGNUMs, and we do not (in principle)
193 * have access to the internals of them, and locking just the structure is
194 * not very useful. Currently, memory locking is not implemented.
197 struct sshkey **host_keys; /* all private host keys */
198 struct sshkey **host_pubkeys; /* all public host keys */
199 struct sshkey **host_certificates; /* all public host certificates */
203 /* This is set to true when a signal is received. */
204 static volatile sig_atomic_t received_sighup = 0;
205 static volatile sig_atomic_t received_sigterm = 0;
207 /* session identifier, used by RSA-auth */
208 u_char session_id[16];
211 u_char *session_id2 = NULL;
212 u_int session_id2_len = 0;
214 /* record remote hostname or ip */
215 u_int utmp_len = HOST_NAME_MAX+1;
217 /* options.max_startup sized array of fd ints */
218 int *startup_pipes = NULL;
219 int startup_pipe; /* in child */
221 /* variables used for privilege separation */
222 int use_privsep = -1;
223 struct monitor *pmonitor = NULL;
224 int privsep_is_preauth = 1;
225 static int privsep_chroot = 1;
227 /* global authentication context */
228 Authctxt *the_authctxt = NULL;
230 /* sshd_config buffer */
233 /* message to be displayed after login */
236 /* Unprivileged user */
237 struct passwd *privsep_pw = NULL;
239 /* Prototypes for various functions defined later in this file. */
240 void destroy_sensitive_data(void);
241 void demote_sensitive_data(void);
242 static void do_ssh2_kex(void);
245 * Close all listening sockets
248 close_listen_socks(void)
252 for (i = 0; i < num_listen_socks; i++)
253 close(listen_socks[i]);
254 num_listen_socks = -1;
258 close_startup_pipes(void)
263 for (i = 0; i < options.max_startups; i++)
264 if (startup_pipes[i] != -1)
265 close(startup_pipes[i]);
269 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
270 * the effect is to reread the configuration file (and to regenerate
276 sighup_handler(int sig)
278 int save_errno = errno;
281 signal(SIGHUP, sighup_handler);
286 * Called from the main program after receiving SIGHUP.
287 * Restarts the server.
292 logit("Received SIGHUP; restarting.");
293 if (options.pid_file != NULL)
294 unlink(options.pid_file);
295 platform_pre_restart();
296 close_listen_socks();
297 close_startup_pipes();
298 alarm(0); /* alarm timer persists across exec */
299 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
300 execv(saved_argv[0], saved_argv);
301 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
307 * Generic signal handler for terminating signals in the master daemon.
311 sigterm_handler(int sig)
313 received_sigterm = sig;
317 * SIGCHLD handler. This is called whenever a child dies. This will then
318 * reap any zombies left by exited children.
322 main_sigchld_handler(int sig)
324 int save_errno = errno;
328 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
329 (pid < 0 && errno == EINTR))
332 signal(SIGCHLD, main_sigchld_handler);
337 * Signal handler for the alarm after the login grace period has expired.
341 grace_alarm_handler(int sig)
343 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
344 kill(pmonitor->m_pid, SIGALRM);
347 * Try to kill any processes that we have spawned, E.g. authorized
348 * keys command helpers.
350 if (getpgid(0) == getpid()) {
351 signal(SIGTERM, SIG_IGN);
355 /* Log error and exit. */
356 sigdie("Timeout before authentication for %s port %d",
357 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state));
361 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out)
364 int remote_major, remote_minor;
366 char buf[256]; /* Must not be larger than remote_version. */
367 char remote_version[256]; /* Must be at least as big as buf. */
369 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n",
370 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
371 *options.version_addendum == '\0' ? "" : " ",
372 options.version_addendum);
374 /* Send our protocol version identification. */
375 if (atomicio(vwrite, sock_out, server_version_string,
376 strlen(server_version_string))
377 != strlen(server_version_string)) {
378 logit("Could not write ident string to %s port %d",
379 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
383 /* Read other sides version identification. */
384 memset(buf, 0, sizeof(buf));
385 for (i = 0; i < sizeof(buf) - 1; i++) {
386 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
387 logit("Did not receive identification string "
389 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
392 if (buf[i] == '\r') {
394 /* Kludge for F-Secure Macintosh < 1.0.2 */
396 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
400 if (buf[i] == '\n') {
405 buf[sizeof(buf) - 1] = 0;
406 client_version_string = xstrdup(buf);
409 * Check that the versions match. In future this might accept
410 * several versions and set appropriate flags to handle them.
412 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
413 &remote_major, &remote_minor, remote_version) != 3) {
414 s = "Protocol mismatch.\n";
415 (void) atomicio(vwrite, sock_out, s, strlen(s));
416 logit("Bad protocol version identification '%.100s' "
417 "from %s port %d", client_version_string,
418 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
423 debug("Client protocol version %d.%d; client software version %.100s",
424 remote_major, remote_minor, remote_version);
426 ssh->compat = compat_datafellows(remote_version);
428 if ((ssh->compat & SSH_BUG_PROBE) != 0) {
429 logit("probed from %s port %d with %s. Don't panic.",
430 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
431 client_version_string);
434 if ((ssh->compat & SSH_BUG_SCANNER) != 0) {
435 logit("scanned from %s port %d with %s. Don't panic.",
436 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
437 client_version_string);
440 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
441 logit("Client version \"%.100s\" uses unsafe RSA signature "
442 "scheme; disabling use of RSA keys", remote_version);
444 if ((ssh->compat & SSH_BUG_DERIVEKEY) != 0) {
445 fatal("Client version \"%.100s\" uses unsafe key agreement; "
446 "refusing connection", remote_version);
449 chop(server_version_string);
450 debug("Local version string %.200s", server_version_string);
452 if (remote_major != 2 ||
453 (remote_major == 1 && remote_minor != 99)) {
454 s = "Protocol major versions differ.\n";
455 (void) atomicio(vwrite, sock_out, s, strlen(s));
458 logit("Protocol major versions differ for %s port %d: "
460 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
461 server_version_string, client_version_string);
466 /* Destroy the host and server keys. They will no longer be needed. */
468 destroy_sensitive_data(void)
472 for (i = 0; i < options.num_host_key_files; i++) {
473 if (sensitive_data.host_keys[i]) {
474 key_free(sensitive_data.host_keys[i]);
475 sensitive_data.host_keys[i] = NULL;
477 if (sensitive_data.host_certificates[i]) {
478 key_free(sensitive_data.host_certificates[i]);
479 sensitive_data.host_certificates[i] = NULL;
484 /* Demote private to public keys for network child */
486 demote_sensitive_data(void)
491 for (i = 0; i < options.num_host_key_files; i++) {
492 if (sensitive_data.host_keys[i]) {
493 tmp = key_demote(sensitive_data.host_keys[i]);
494 key_free(sensitive_data.host_keys[i]);
495 sensitive_data.host_keys[i] = tmp;
497 /* Certs do not need demotion */
509 arc4random_stir(); /* noop on recent arc4random() implementations */
510 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
513 RAND_seed(rnd, sizeof(rnd));
514 /* give libcrypto a chance to notice the PID change */
515 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
516 fatal("%s: RAND_bytes failed", __func__);
519 explicit_bzero(rnd, sizeof(rnd));
523 privsep_preauth_child(void)
527 /* Enable challenge-response authentication for privilege separation */
528 privsep_challenge_enable();
531 /* Cache supported mechanism OIDs for later use */
532 if (options.gss_authentication)
533 ssh_gssapi_prepare_supported_oids();
538 /* Demote the private keys to public keys. */
539 demote_sensitive_data();
541 /* Demote the child */
542 if (privsep_chroot) {
543 /* Change our root directory */
544 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
545 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
547 if (chdir("/") == -1)
548 fatal("chdir(\"/\"): %s", strerror(errno));
550 /* Drop our privileges */
551 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
552 (u_int)privsep_pw->pw_gid);
553 gidset[0] = privsep_pw->pw_gid;
554 if (setgroups(1, gidset) < 0)
555 fatal("setgroups: %.100s", strerror(errno));
556 permanently_set_uid(privsep_pw);
561 privsep_preauth(Authctxt *authctxt)
565 struct ssh_sandbox *box = NULL;
567 /* Set up unprivileged child process to deal with network data */
568 pmonitor = monitor_init();
569 /* Store a pointer to the kex for later rekeying */
570 pmonitor->m_pkex = &active_state->kex;
572 if (use_privsep == PRIVSEP_ON)
573 box = ssh_sandbox_init(pmonitor);
576 fatal("fork of unprivileged child failed");
577 } else if (pid != 0) {
578 debug2("Network child is on pid %ld", (long)pid);
580 pmonitor->m_pid = pid;
582 r = ssh_get_authentication_socket(&auth_sock);
584 error("Could not get agent socket: %s",
590 ssh_sandbox_parent_preauth(box, pid);
591 monitor_child_preauth(authctxt, pmonitor);
593 /* Wait for the child's exit status */
594 while (waitpid(pid, &status, 0) < 0) {
597 pmonitor->m_pid = -1;
598 fatal("%s: waitpid: %s", __func__, strerror(errno));
600 privsep_is_preauth = 0;
601 pmonitor->m_pid = -1;
602 if (WIFEXITED(status)) {
603 if (WEXITSTATUS(status) != 0)
604 fatal("%s: preauth child exited with status %d",
605 __func__, WEXITSTATUS(status));
606 } else if (WIFSIGNALED(status))
607 fatal("%s: preauth child terminated by signal %d",
608 __func__, WTERMSIG(status));
610 ssh_sandbox_parent_finish(box);
614 close(pmonitor->m_sendfd);
615 close(pmonitor->m_log_recvfd);
617 /* Arrange for logging to be sent to the monitor */
618 set_log_handler(mm_log_handler, pmonitor);
620 privsep_preauth_child();
621 setproctitle("%s", "[net]");
623 ssh_sandbox_child(box);
630 privsep_postauth(Authctxt *authctxt)
632 #ifdef DISABLE_FD_PASSING
635 if (authctxt->pw->pw_uid == 0) {
637 /* File descriptor passing is broken or root login */
642 /* New socket pair */
643 monitor_reinit(pmonitor);
645 pmonitor->m_pid = fork();
646 if (pmonitor->m_pid == -1)
647 fatal("fork of unprivileged child failed");
648 else if (pmonitor->m_pid != 0) {
649 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
650 buffer_clear(&loginmsg);
651 monitor_clear_keystate(pmonitor);
652 monitor_child_postauth(pmonitor);
660 close(pmonitor->m_sendfd);
661 pmonitor->m_sendfd = -1;
663 /* Demote the private keys to public keys. */
664 demote_sensitive_data();
668 /* Drop privileges */
669 do_setusercontext(authctxt->pw);
672 /* It is safe now to apply the key state */
673 monitor_apply_keystate(pmonitor);
676 * Tell the packet layer that authentication was successful, since
677 * this information is not part of the key state.
679 packet_set_authenticated();
683 list_hostkey_types(void)
692 for (i = 0; i < options.num_host_key_files; i++) {
693 key = sensitive_data.host_keys[i];
695 key = sensitive_data.host_pubkeys[i];
698 /* Check that the key is accepted in HostkeyAlgorithms */
699 if (match_pattern_list(sshkey_ssh_name(key),
700 options.hostkeyalgorithms, 0) != 1) {
701 debug3("%s: %s key not permitted by HostkeyAlgorithms",
702 __func__, sshkey_ssh_name(key));
710 if (buffer_len(&b) > 0)
711 buffer_append(&b, ",", 1);
712 p = key_ssh_name(key);
713 buffer_append(&b, p, strlen(p));
715 /* for RSA we also support SHA2 signatures */
716 if (key->type == KEY_RSA) {
717 p = ",rsa-sha2-512,rsa-sha2-256";
718 buffer_append(&b, p, strlen(p));
722 /* If the private key has a cert peer, then list that too */
723 key = sensitive_data.host_certificates[i];
730 case KEY_ED25519_CERT:
731 if (buffer_len(&b) > 0)
732 buffer_append(&b, ",", 1);
733 p = key_ssh_name(key);
734 buffer_append(&b, p, strlen(p));
738 if ((ret = sshbuf_dup_string(&b)) == NULL)
739 fatal("%s: sshbuf_dup_string failed", __func__);
741 debug("list_hostkey_types: %s", ret);
745 static struct sshkey *
746 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
751 for (i = 0; i < options.num_host_key_files; i++) {
756 case KEY_ED25519_CERT:
757 key = sensitive_data.host_certificates[i];
760 key = sensitive_data.host_keys[i];
761 if (key == NULL && !need_private)
762 key = sensitive_data.host_pubkeys[i];
765 if (key != NULL && key->type == type &&
766 (key->type != KEY_ECDSA || key->ecdsa_nid == nid))
767 return need_private ?
768 sensitive_data.host_keys[i] : key;
774 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
776 return get_hostkey_by_type(type, nid, 0, ssh);
780 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
782 return get_hostkey_by_type(type, nid, 1, ssh);
786 get_hostkey_by_index(int ind)
788 if (ind < 0 || ind >= options.num_host_key_files)
790 return (sensitive_data.host_keys[ind]);
794 get_hostkey_public_by_index(int ind, struct ssh *ssh)
796 if (ind < 0 || ind >= options.num_host_key_files)
798 return (sensitive_data.host_pubkeys[ind]);
802 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
806 for (i = 0; i < options.num_host_key_files; i++) {
807 if (key_is_cert(key)) {
808 if (key == sensitive_data.host_certificates[i] ||
809 (compare && sensitive_data.host_certificates[i] &&
811 sensitive_data.host_certificates[i])))
814 if (key == sensitive_data.host_keys[i] ||
815 (compare && sensitive_data.host_keys[i] &&
816 sshkey_equal(key, sensitive_data.host_keys[i])))
818 if (key == sensitive_data.host_pubkeys[i] ||
819 (compare && sensitive_data.host_pubkeys[i] &&
820 sshkey_equal(key, sensitive_data.host_pubkeys[i])))
827 /* Inform the client of all hostkeys */
829 notify_hostkeys(struct ssh *ssh)
836 /* Some clients cannot cope with the hostkeys message, skip those. */
837 if (datafellows & SSH_BUG_HOSTKEYS)
840 if ((buf = sshbuf_new()) == NULL)
841 fatal("%s: sshbuf_new", __func__);
842 for (i = nkeys = 0; i < options.num_host_key_files; i++) {
843 key = get_hostkey_public_by_index(i, ssh);
844 if (key == NULL || key->type == KEY_UNSPEC ||
847 fp = sshkey_fingerprint(key, options.fingerprint_hash,
849 debug3("%s: key %d: %s %s", __func__, i,
850 sshkey_ssh_name(key), fp);
853 packet_start(SSH2_MSG_GLOBAL_REQUEST);
854 packet_put_cstring("hostkeys-00@openssh.com");
855 packet_put_char(0); /* want-reply */
858 if ((r = sshkey_putb(key, buf)) != 0)
859 fatal("%s: couldn't put hostkey %d: %s",
860 __func__, i, ssh_err(r));
861 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf));
864 debug3("%s: sent %d hostkeys", __func__, nkeys);
866 fatal("%s: no hostkeys", __func__);
872 * returns 1 if connection should be dropped, 0 otherwise.
873 * dropping starts at connection #max_startups_begin with a probability
874 * of (max_startups_rate/100). the probability increases linearly until
875 * all connections are dropped for startups > max_startups
878 drop_connection(int startups)
882 if (startups < options.max_startups_begin)
884 if (startups >= options.max_startups)
886 if (options.max_startups_rate == 100)
889 p = 100 - options.max_startups_rate;
890 p *= startups - options.max_startups_begin;
891 p /= options.max_startups - options.max_startups_begin;
892 p += options.max_startups_rate;
893 r = arc4random_uniform(100);
895 debug("drop_connection: p %d, r %d", p, r);
896 return (r < p) ? 1 : 0;
902 fprintf(stderr, "%s, %s\n",
905 SSLeay_version(SSLEAY_VERSION)
911 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n"
912 " [-E log_file] [-f config_file] [-g login_grace_time]\n"
913 " [-h host_key_file] [-o option] [-p port] [-u len]\n"
919 send_rexec_state(int fd, struct sshbuf *conf)
924 debug3("%s: entering fd = %d config len %zu", __func__, fd,
928 * Protocol from reexec master to child:
929 * string configuration
930 * string rngseed (only if OpenSSL is not self-seeded)
932 if ((m = sshbuf_new()) == NULL)
933 fatal("%s: sshbuf_new failed", __func__);
934 if ((r = sshbuf_put_stringb(m, conf)) != 0)
935 fatal("%s: buffer error: %s", __func__, ssh_err(r));
937 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
938 rexec_send_rng_seed(m);
941 if (ssh_msg_send(fd, 0, m) == -1)
942 fatal("%s: ssh_msg_send failed", __func__);
946 debug3("%s: done", __func__);
950 recv_rexec_state(int fd, Buffer *conf)
956 debug3("%s: entering fd = %d", __func__, fd);
960 if (ssh_msg_recv(fd, &m) == -1)
961 fatal("%s: ssh_msg_recv failed", __func__);
962 if (buffer_get_char(&m) != 0)
963 fatal("%s: rexec version mismatch", __func__);
965 cp = buffer_get_string(&m, &len);
967 buffer_append(conf, cp, len);
970 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
971 rexec_recv_rng_seed(&m);
976 debug3("%s: done", __func__);
979 /* Accept a connection from inetd */
981 server_accept_inetd(int *sock_in, int *sock_out)
987 close(REEXEC_CONFIG_PASS_FD);
988 *sock_in = *sock_out = dup(STDIN_FILENO);
990 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
991 close(REEXEC_STARTUP_PIPE_FD);
994 *sock_in = dup(STDIN_FILENO);
995 *sock_out = dup(STDOUT_FILENO);
998 * We intentionally do not close the descriptors 0, 1, and 2
999 * as our code for setting the descriptors won't work if
1000 * ttyfd happens to be one of those.
1002 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1003 dup2(fd, STDIN_FILENO);
1004 dup2(fd, STDOUT_FILENO);
1006 dup2(fd, STDERR_FILENO);
1007 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO))
1010 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1014 * Listen for TCP connections
1019 int ret, listen_sock, on = 1;
1020 struct addrinfo *ai;
1021 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1023 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1024 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1026 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1027 fatal("Too many listen sockets. "
1028 "Enlarge MAX_LISTEN_SOCKS");
1029 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1030 ntop, sizeof(ntop), strport, sizeof(strport),
1031 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1032 error("getnameinfo failed: %.100s",
1033 ssh_gai_strerror(ret));
1036 /* Create socket for listening. */
1037 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1039 if (listen_sock < 0) {
1040 /* kernel may not support ipv6 */
1041 verbose("socket: %.100s", strerror(errno));
1044 if (set_nonblock(listen_sock) == -1) {
1048 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
1049 verbose("socket: CLOEXEC: %s", strerror(errno));
1054 * Set socket options.
1055 * Allow local port reuse in TIME_WAIT.
1057 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1058 &on, sizeof(on)) == -1)
1059 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1061 /* Only communicate in IPv6 over AF_INET6 sockets. */
1062 if (ai->ai_family == AF_INET6)
1063 sock_set_v6only(listen_sock);
1065 debug("Bind to port %s on %s.", strport, ntop);
1067 /* Bind the socket to the desired port. */
1068 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1069 error("Bind to port %s on %s failed: %.200s.",
1070 strport, ntop, strerror(errno));
1074 listen_socks[num_listen_socks] = listen_sock;
1077 /* Start listening on the port. */
1078 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1079 fatal("listen on [%s]:%s: %.100s",
1080 ntop, strport, strerror(errno));
1081 logit("Server listening on %s port %s.", ntop, strport);
1083 freeaddrinfo(options.listen_addrs);
1085 if (!num_listen_socks)
1086 fatal("Cannot bind any address.");
1090 * The main TCP accept loop. Note that, for the non-debug case, returns
1091 * from this function are in a forked subprocess.
1094 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1097 int i, j, ret, maxfd;
1099 int startup_p[2] = { -1 , -1 };
1100 struct sockaddr_storage from;
1105 /* setup fd set for accept */
1108 for (i = 0; i < num_listen_socks; i++)
1109 if (listen_socks[i] > maxfd)
1110 maxfd = listen_socks[i];
1111 /* pipes connected to unauthenticated childs */
1112 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1113 for (i = 0; i < options.max_startups; i++)
1114 startup_pipes[i] = -1;
1117 * Stay listening for connections until the system crashes or
1118 * the daemon is killed with a signal.
1121 if (received_sighup)
1124 fdset = xcalloc(howmany(maxfd + 1, NFDBITS),
1127 for (i = 0; i < num_listen_socks; i++)
1128 FD_SET(listen_socks[i], fdset);
1129 for (i = 0; i < options.max_startups; i++)
1130 if (startup_pipes[i] != -1)
1131 FD_SET(startup_pipes[i], fdset);
1133 /* Wait in select until there is a connection. */
1134 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1135 if (ret < 0 && errno != EINTR)
1136 error("select: %.100s", strerror(errno));
1137 if (received_sigterm) {
1138 logit("Received signal %d; terminating.",
1139 (int) received_sigterm);
1140 close_listen_socks();
1141 if (options.pid_file != NULL)
1142 unlink(options.pid_file);
1143 exit(received_sigterm == SIGTERM ? 0 : 255);
1148 for (i = 0; i < options.max_startups; i++)
1149 if (startup_pipes[i] != -1 &&
1150 FD_ISSET(startup_pipes[i], fdset)) {
1152 * the read end of the pipe is ready
1153 * if the child has closed the pipe
1154 * after successful authentication
1155 * or if the child has died
1157 close(startup_pipes[i]);
1158 startup_pipes[i] = -1;
1161 for (i = 0; i < num_listen_socks; i++) {
1162 if (!FD_ISSET(listen_socks[i], fdset))
1164 fromlen = sizeof(from);
1165 *newsock = accept(listen_socks[i],
1166 (struct sockaddr *)&from, &fromlen);
1168 if (errno != EINTR && errno != EWOULDBLOCK &&
1169 errno != ECONNABORTED && errno != EAGAIN)
1170 error("accept: %.100s",
1172 if (errno == EMFILE || errno == ENFILE)
1176 if (unset_nonblock(*newsock) == -1) {
1180 if (drop_connection(startups) == 1) {
1181 char *laddr = get_local_ipaddr(*newsock);
1182 char *raddr = get_peer_ipaddr(*newsock);
1184 verbose("drop connection #%d from [%s]:%d "
1185 "on [%s]:%d past MaxStartups", startups,
1186 raddr, get_peer_port(*newsock),
1187 laddr, get_local_port(*newsock));
1193 if (pipe(startup_p) == -1) {
1198 if (rexec_flag && socketpair(AF_UNIX,
1199 SOCK_STREAM, 0, config_s) == -1) {
1200 error("reexec socketpair: %s",
1203 close(startup_p[0]);
1204 close(startup_p[1]);
1208 for (j = 0; j < options.max_startups; j++)
1209 if (startup_pipes[j] == -1) {
1210 startup_pipes[j] = startup_p[0];
1211 if (maxfd < startup_p[0])
1212 maxfd = startup_p[0];
1218 * Got connection. Fork a child to handle it, unless
1219 * we are in debugging mode.
1223 * In debugging mode. Close the listening
1224 * socket, and start processing the
1225 * connection without forking.
1227 debug("Server will not fork when running in debugging mode.");
1228 close_listen_socks();
1229 *sock_in = *newsock;
1230 *sock_out = *newsock;
1231 close(startup_p[0]);
1232 close(startup_p[1]);
1236 send_rexec_state(config_s[0],
1244 * Normal production daemon. Fork, and have
1245 * the child process the connection. The
1246 * parent continues listening.
1248 platform_pre_fork();
1249 if ((pid = fork()) == 0) {
1251 * Child. Close the listening and
1252 * max_startup sockets. Start using
1253 * the accepted socket. Reinitialize
1254 * logging (since our pid has changed).
1255 * We break out of the loop to handle
1258 platform_post_fork_child();
1259 startup_pipe = startup_p[1];
1260 close_startup_pipes();
1261 close_listen_socks();
1262 *sock_in = *newsock;
1263 *sock_out = *newsock;
1264 log_init(__progname,
1266 options.log_facility,
1273 /* Parent. Stay in the loop. */
1274 platform_post_fork_parent(pid);
1276 error("fork: %.100s", strerror(errno));
1278 debug("Forked child %ld.", (long)pid);
1280 close(startup_p[1]);
1283 send_rexec_state(config_s[0], &cfg);
1290 * Ensure that our random state differs
1291 * from that of the child
1294 arc4random_buf(rnd, sizeof(rnd));
1296 RAND_seed(rnd, sizeof(rnd));
1297 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
1298 fatal("%s: RAND_bytes failed", __func__);
1300 explicit_bzero(rnd, sizeof(rnd));
1303 /* child process check (or debug mode) */
1304 if (num_listen_socks < 0)
1310 * If IP options are supported, make sure there are none (log and
1311 * return an error if any are found). Basically we are worried about
1312 * source routing; it can be used to pretend you are somebody
1313 * (ip-address) you are not. That itself may be "almost acceptable"
1314 * under certain circumstances, but rhosts autentication is useless
1315 * if source routing is accepted. Notice also that if we just dropped
1316 * source routing here, the other side could use IP spoofing to do
1317 * rest of the interaction and could still bypass security. So we
1318 * exit here if we detect any IP options.
1321 check_ip_options(struct ssh *ssh)
1324 int sock_in = ssh_packet_get_connection_in(ssh);
1325 struct sockaddr_storage from;
1327 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
1328 char text[sizeof(opts) * 3 + 1];
1330 memset(&from, 0, sizeof(from));
1331 if (getpeername(sock_in, (struct sockaddr *)&from,
1334 if (from.ss_family != AF_INET)
1336 /* XXX IPv6 options? */
1338 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
1339 &option_size) >= 0 && option_size != 0) {
1341 for (i = 0; i < option_size; i++)
1342 snprintf(text + i*3, sizeof(text) - i*3,
1344 fatal("Connection from %.100s port %d with IP opts: %.800s",
1345 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
1348 #endif /* IP_OPTIONS */
1352 * Main program for the daemon.
1355 main(int ac, char **av)
1357 struct ssh *ssh = NULL;
1358 extern char *optarg;
1360 int r, opt, i, j, on = 1, already_daemon;
1361 int sock_in = -1, sock_out = -1, newsock = -1;
1362 const char *remote_ip;
1364 char *fp, *line, *laddr, *logfile = NULL;
1365 int config_s[2] = { -1 , -1 };
1367 u_int64_t ibytes, obytes;
1370 struct sshkey *pubkey;
1373 struct connection_info *connection_info = get_connection_info(0, 0);
1375 ssh_malloc_init(); /* must be called before any mallocs */
1377 #ifdef HAVE_SECUREWARE
1378 (void)set_auth_parameters(ac, av);
1380 __progname = ssh_get_progname(av[0]);
1382 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1385 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1386 for (i = 0; i < ac; i++)
1387 saved_argv[i] = xstrdup(av[i]);
1388 saved_argv[i] = NULL;
1390 #ifndef HAVE_SETPROCTITLE
1391 /* Prepare for later setproctitle emulation */
1392 compat_init_setproctitle(ac, av);
1396 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1397 debug("setgroups(): %.200s", strerror(errno));
1399 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1402 /* Initialize configuration options to their default values. */
1403 initialize_server_options(&options);
1405 /* Parse command-line arguments. */
1406 while ((opt = getopt(ac, av,
1407 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) {
1410 options.address_family = AF_INET;
1413 options.address_family = AF_INET6;
1416 config_file_name = optarg;
1419 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1420 fprintf(stderr, "too many host certificates.\n");
1423 options.host_cert_files[options.num_host_cert_files++] =
1424 derelativise_path(optarg);
1427 if (debug_flag == 0) {
1429 options.log_level = SYSLOG_LEVEL_DEBUG1;
1430 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1431 options.log_level++;
1456 options.log_level = SYSLOG_LEVEL_QUIET;
1459 /* protocol 1, ignored */
1462 options.ports_from_cmdline = 1;
1463 if (options.num_ports >= MAX_PORTS) {
1464 fprintf(stderr, "too many ports.\n");
1467 options.ports[options.num_ports++] = a2port(optarg);
1468 if (options.ports[options.num_ports-1] <= 0) {
1469 fprintf(stderr, "Bad port number.\n");
1474 if ((options.login_grace_time = convtime(optarg)) == -1) {
1475 fprintf(stderr, "Invalid login grace time.\n");
1480 /* protocol 1, ignored */
1483 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1484 fprintf(stderr, "too many host keys.\n");
1487 options.host_key_files[options.num_host_key_files++] =
1488 derelativise_path(optarg);
1497 if (parse_server_match_testspec(connection_info,
1502 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1503 if (utmp_len > HOST_NAME_MAX+1) {
1504 fprintf(stderr, "Invalid utmp length.\n");
1509 line = xstrdup(optarg);
1510 if (process_server_config_line(&options, line,
1511 "command-line", 0, NULL, NULL) != 0)
1521 if (rexeced_flag || inetd_flag)
1523 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1524 fatal("sshd re-exec requires execution with an absolute path");
1526 closefrom(REEXEC_MIN_FREE_FD);
1528 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1531 OpenSSL_add_all_algorithms();
1534 /* If requested, redirect the logs to the specified logfile. */
1535 if (logfile != NULL)
1536 log_redirect_stderr_to(logfile);
1538 * Force logging to stderr until we have loaded the private host
1539 * key (unless started from inetd)
1541 log_init(__progname,
1542 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1543 SYSLOG_LEVEL_INFO : options.log_level,
1544 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1545 SYSLOG_FACILITY_AUTH : options.log_facility,
1546 log_stderr || !inetd_flag);
1549 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1550 * root's environment
1552 if (getenv("KRB5CCNAME") != NULL)
1553 (void) unsetenv("KRB5CCNAME");
1556 /* Cray can define user privs drop all privs now!
1557 * Not needed on PRIV_SU systems!
1562 sensitive_data.have_ssh2_key = 0;
1565 * If we're doing an extended config test, make sure we have all of
1566 * the parameters we need. If we're not doing an extended test,
1567 * do not silently ignore connection test params.
1569 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0)
1570 fatal("user, host and addr are all required when testing "
1572 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0)
1573 fatal("Config test connection parameter (-C) provided without "
1576 /* Fetch our configuration */
1579 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1580 else if (strcasecmp(config_file_name, "none") != 0)
1581 load_server_config(config_file_name, &cfg);
1583 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1588 /* Fill in default values for those options not explicitly set. */
1589 fill_default_server_options(&options);
1591 /* challenge-response is implemented via keyboard interactive */
1592 if (options.challenge_response_authentication)
1593 options.kbd_interactive_authentication = 1;
1595 /* Check that options are sensible */
1596 if (options.authorized_keys_command_user == NULL &&
1597 (options.authorized_keys_command != NULL &&
1598 strcasecmp(options.authorized_keys_command, "none") != 0))
1599 fatal("AuthorizedKeysCommand set without "
1600 "AuthorizedKeysCommandUser");
1601 if (options.authorized_principals_command_user == NULL &&
1602 (options.authorized_principals_command != NULL &&
1603 strcasecmp(options.authorized_principals_command, "none") != 0))
1604 fatal("AuthorizedPrincipalsCommand set without "
1605 "AuthorizedPrincipalsCommandUser");
1608 * Check whether there is any path through configured auth methods.
1609 * Unfortunately it is not possible to verify this generally before
1610 * daemonisation in the presence of Match block, but this catches
1611 * and warns for trivial misconfigurations that could break login.
1613 if (options.num_auth_methods != 0) {
1614 for (n = 0; n < options.num_auth_methods; n++) {
1615 if (auth2_methods_valid(options.auth_methods[n],
1619 if (n >= options.num_auth_methods)
1620 fatal("AuthenticationMethods cannot be satisfied by "
1621 "enabled authentication methods");
1624 /* Check that there are no remaining arguments. */
1626 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1630 debug("sshd version %s, %s", SSH_VERSION,
1632 SSLeay_version(SSLEAY_VERSION)
1638 /* Store privilege separation user for later use if required. */
1639 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0);
1640 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1641 if (privsep_chroot || options.kerberos_authentication)
1642 fatal("Privilege separation user %s does not exist",
1645 explicit_bzero(privsep_pw->pw_passwd,
1646 strlen(privsep_pw->pw_passwd));
1647 privsep_pw = pwcopy(privsep_pw);
1648 free(privsep_pw->pw_passwd);
1649 privsep_pw->pw_passwd = xstrdup("*");
1653 /* load host keys */
1654 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1655 sizeof(struct sshkey *));
1656 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1657 sizeof(struct sshkey *));
1659 if (options.host_key_agent) {
1660 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1661 setenv(SSH_AUTHSOCKET_ENV_NAME,
1662 options.host_key_agent, 1);
1663 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1666 error("Could not connect to agent \"%s\": %s",
1667 options.host_key_agent, ssh_err(r));
1670 for (i = 0; i < options.num_host_key_files; i++) {
1671 if (options.host_key_files[i] == NULL)
1673 key = key_load_private(options.host_key_files[i], "", NULL);
1674 pubkey = key_load_public(options.host_key_files[i], NULL);
1676 if (pubkey == NULL && key != NULL)
1677 pubkey = key_demote(key);
1678 sensitive_data.host_keys[i] = key;
1679 sensitive_data.host_pubkeys[i] = pubkey;
1681 if (key == NULL && pubkey != NULL && have_agent) {
1682 debug("will rely on agent for hostkey %s",
1683 options.host_key_files[i]);
1684 keytype = pubkey->type;
1685 } else if (key != NULL) {
1686 keytype = key->type;
1688 error("Could not load host key: %s",
1689 options.host_key_files[i]);
1690 sensitive_data.host_keys[i] = NULL;
1691 sensitive_data.host_pubkeys[i] = NULL;
1700 if (have_agent || key != NULL)
1701 sensitive_data.have_ssh2_key = 1;
1704 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
1705 SSH_FP_DEFAULT)) == NULL)
1706 fatal("sshkey_fingerprint failed");
1707 debug("%s host key #%d: %s %s",
1708 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
1711 if (!sensitive_data.have_ssh2_key) {
1712 logit("sshd: no hostkeys available -- exiting.");
1717 * Load certificates. They are stored in an array at identical
1718 * indices to the public keys that they relate to.
1720 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1721 sizeof(struct sshkey *));
1722 for (i = 0; i < options.num_host_key_files; i++)
1723 sensitive_data.host_certificates[i] = NULL;
1725 for (i = 0; i < options.num_host_cert_files; i++) {
1726 if (options.host_cert_files[i] == NULL)
1728 key = key_load_public(options.host_cert_files[i], NULL);
1730 error("Could not load host certificate: %s",
1731 options.host_cert_files[i]);
1734 if (!key_is_cert(key)) {
1735 error("Certificate file is not a certificate: %s",
1736 options.host_cert_files[i]);
1740 /* Find matching private key */
1741 for (j = 0; j < options.num_host_key_files; j++) {
1742 if (key_equal_public(key,
1743 sensitive_data.host_keys[j])) {
1744 sensitive_data.host_certificates[j] = key;
1748 if (j >= options.num_host_key_files) {
1749 error("No matching private key for certificate: %s",
1750 options.host_cert_files[i]);
1754 sensitive_data.host_certificates[j] = key;
1755 debug("host certificate: #%d type %d %s", j, key->type,
1759 if (privsep_chroot) {
1762 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1763 (S_ISDIR(st.st_mode) == 0))
1764 fatal("Missing privilege separation directory: %s",
1765 _PATH_PRIVSEP_CHROOT_DIR);
1768 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1769 (st.st_uid != getuid () ||
1770 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1772 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1774 fatal("%s must be owned by root and not group or "
1775 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1778 if (test_flag > 1) {
1779 if (server_match_spec_complete(connection_info) == 1)
1780 parse_server_match_config(&options, connection_info);
1781 dump_config(&options);
1784 /* Configuration looks good, so exit if in test mode. */
1789 * Clear out any supplemental groups we may have inherited. This
1790 * prevents inadvertent creation of files with bad modes (in the
1791 * portable version at least, it's certainly possible for PAM
1792 * to create a file, and we can't control the code in every
1793 * module which might be used).
1795 if (setgroups(0, NULL) < 0)
1796 debug("setgroups() failed: %.200s", strerror(errno));
1799 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1800 for (i = 0; i < rexec_argc; i++) {
1801 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1802 rexec_argv[i] = saved_argv[i];
1804 rexec_argv[rexec_argc] = "-R";
1805 rexec_argv[rexec_argc + 1] = NULL;
1808 /* Ensure that umask disallows at least group and world write */
1809 new_umask = umask(0077) | 0022;
1810 (void) umask(new_umask);
1812 /* Initialize the log (it is reinitialized below in case we forked). */
1813 if (debug_flag && (!inetd_flag || rexeced_flag))
1815 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1818 * If not in debugging mode, not started from inetd and not already
1819 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
1820 * terminal, and fork. The original process exits.
1822 already_daemon = daemonized();
1823 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
1825 if (daemon(0, 0) < 0)
1826 fatal("daemon() failed: %.200s", strerror(errno));
1828 disconnect_controlling_tty();
1830 /* Reinitialize the log (because of the fork above). */
1831 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1833 /* Chdir to the root directory so that the current disk can be
1834 unmounted if desired. */
1835 if (chdir("/") == -1)
1836 error("chdir(\"/\"): %s", strerror(errno));
1838 /* ignore SIGPIPE */
1839 signal(SIGPIPE, SIG_IGN);
1841 /* Get a connection, either from inetd or a listening TCP socket */
1843 server_accept_inetd(&sock_in, &sock_out);
1845 platform_pre_listen();
1848 signal(SIGHUP, sighup_handler);
1849 signal(SIGCHLD, main_sigchld_handler);
1850 signal(SIGTERM, sigterm_handler);
1851 signal(SIGQUIT, sigterm_handler);
1854 * Write out the pid file after the sigterm handler
1855 * is setup and the listen sockets are bound
1857 if (options.pid_file != NULL && !debug_flag) {
1858 FILE *f = fopen(options.pid_file, "w");
1861 error("Couldn't create pid file \"%s\": %s",
1862 options.pid_file, strerror(errno));
1864 fprintf(f, "%ld\n", (long) getpid());
1869 /* Accept a connection and return in a forked child */
1870 server_accept_loop(&sock_in, &sock_out,
1871 &newsock, config_s);
1874 /* This is the child processing a new connection. */
1875 setproctitle("%s", "[accepted]");
1878 * Create a new session and process group since the 4.4BSD
1879 * setlogin() affects the entire process group. We don't
1880 * want the child to be able to affect the parent.
1882 #if !defined(SSHD_ACQUIRES_CTTY)
1884 * If setsid is called, on some platforms sshd will later acquire a
1885 * controlling terminal which will result in "could not set
1886 * controlling tty" errors.
1888 if (!debug_flag && !inetd_flag && setsid() < 0)
1889 error("setsid: %.100s", strerror(errno));
1895 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1896 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1897 dup2(newsock, STDIN_FILENO);
1898 dup2(STDIN_FILENO, STDOUT_FILENO);
1899 if (startup_pipe == -1)
1900 close(REEXEC_STARTUP_PIPE_FD);
1901 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
1902 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1903 close(startup_pipe);
1904 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1907 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1910 execv(rexec_argv[0], rexec_argv);
1912 /* Reexec has failed, fall back and continue */
1913 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1914 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1915 log_init(__progname, options.log_level,
1916 options.log_facility, log_stderr);
1919 close(REEXEC_CONFIG_PASS_FD);
1920 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1921 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1922 dup2(fd, STDIN_FILENO);
1923 dup2(fd, STDOUT_FILENO);
1924 if (fd > STDERR_FILENO)
1927 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1928 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1931 /* Executed child processes don't need these. */
1932 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1933 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1936 * Disable the key regeneration alarm. We will not regenerate the
1937 * key since we are no longer in a position to give it to anyone. We
1938 * will not restart on SIGHUP since it no longer makes sense.
1941 signal(SIGALRM, SIG_DFL);
1942 signal(SIGHUP, SIG_DFL);
1943 signal(SIGTERM, SIG_DFL);
1944 signal(SIGQUIT, SIG_DFL);
1945 signal(SIGCHLD, SIG_DFL);
1946 signal(SIGINT, SIG_DFL);
1949 * Register our connection. This turns encryption off because we do
1952 packet_set_connection(sock_in, sock_out);
1953 packet_set_server();
1954 ssh = active_state; /* XXX */
1956 check_ip_options(ssh);
1958 /* Prepare the channels layer */
1959 channel_init_channels(ssh);
1960 channel_set_af(ssh, options.address_family);
1961 process_permitopen(ssh, &options);
1963 /* Set SO_KEEPALIVE if requested. */
1964 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1965 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1966 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1968 if ((remote_port = ssh_remote_port(ssh)) < 0) {
1969 debug("ssh_remote_port failed");
1974 * The rest of the code depends on the fact that
1975 * ssh_remote_ipaddr() caches the remote ip, even if
1976 * the socket goes away.
1978 remote_ip = ssh_remote_ipaddr(ssh);
1980 #ifdef SSH_AUDIT_EVENTS
1981 audit_connection_from(remote_ip, remote_port);
1984 /* Log the connection. */
1985 laddr = get_local_ipaddr(sock_in);
1986 verbose("Connection from %s port %d on %s port %d",
1987 remote_ip, remote_port, laddr, ssh_local_port(ssh));
1991 * We don't want to listen forever unless the other side
1992 * successfully authenticates itself. So we set up an alarm which is
1993 * cleared after successful authentication. A limit of zero
1994 * indicates no limit. Note that we don't set the alarm in debugging
1995 * mode; it is just annoying to have the server exit just when you
1996 * are about to discover the bug.
1998 signal(SIGALRM, grace_alarm_handler);
2000 alarm(options.login_grace_time);
2002 sshd_exchange_identification(ssh, sock_in, sock_out);
2003 packet_set_nonblocking();
2005 /* allocate authentication context */
2006 authctxt = xcalloc(1, sizeof(*authctxt));
2008 authctxt->loginmsg = &loginmsg;
2010 /* XXX global for cleanup, access from other modules */
2011 the_authctxt = authctxt;
2013 /* prepare buffer to collect messages to display to user after login */
2014 buffer_init(&loginmsg);
2018 if (privsep_preauth(authctxt) == 1)
2020 } else if (have_agent) {
2021 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
2022 error("Unable to get agent socket: %s", ssh_err(r));
2027 /* perform the key exchange */
2028 /* authenticate user and start session */
2030 do_authentication2(authctxt);
2033 * If we use privilege separation, the unprivileged child transfers
2034 * the current keystate and exits
2037 mm_send_keystate(pmonitor);
2038 packet_clear_keys();
2044 * Cancel the alarm we set to limit the time taken for
2048 signal(SIGALRM, SIG_DFL);
2049 authctxt->authenticated = 1;
2050 if (startup_pipe != -1) {
2051 close(startup_pipe);
2055 #ifdef SSH_AUDIT_EVENTS
2056 audit_event(SSH_AUTH_SUCCESS);
2060 if (options.gss_authentication) {
2061 temporarily_use_uid(authctxt->pw);
2062 ssh_gssapi_storecreds();
2067 if (options.use_pam) {
2074 * In privilege separation, we fork another child and prepare
2075 * file descriptor passing.
2078 privsep_postauth(authctxt);
2079 /* the monitor process [priv] will not return */
2082 packet_set_timeout(options.client_alive_interval,
2083 options.client_alive_count_max);
2085 /* Try to send all our hostkeys to the client */
2086 notify_hostkeys(ssh);
2088 /* Start session. */
2089 do_authenticated(ssh, authctxt);
2091 /* The connection has been terminated. */
2092 packet_get_bytes(&ibytes, &obytes);
2093 verbose("Transferred: sent %llu, received %llu bytes",
2094 (unsigned long long)obytes, (unsigned long long)ibytes);
2096 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2099 if (options.use_pam)
2101 #endif /* USE_PAM */
2103 #ifdef SSH_AUDIT_EVENTS
2104 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2116 sshd_hostkey_sign(struct sshkey *privkey, struct sshkey *pubkey,
2117 u_char **signature, size_t *slen, const u_char *data, size_t dlen,
2118 const char *alg, u_int flag)
2121 u_int xxx_slen, xxx_dlen = dlen;
2124 if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen,
2126 fatal("%s: key_sign failed", __func__);
2129 } else if (use_privsep) {
2130 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen,
2132 fatal("%s: pubkey_sign failed", __func__);
2136 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen,
2137 data, dlen, alg, datafellows)) != 0)
2138 fatal("%s: ssh_agent_sign failed: %s",
2139 __func__, ssh_err(r));
2144 /* SSH2 key exchange */
2148 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
2152 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
2153 options.kex_algorithms);
2154 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
2156 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
2158 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2159 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2161 if (options.compression == COMP_NONE) {
2162 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2163 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2166 if (options.rekey_limit || options.rekey_interval)
2167 packet_set_rekey_limits(options.rekey_limit,
2168 options.rekey_interval);
2170 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
2171 list_hostkey_types());
2173 /* start key exchange */
2174 if ((r = kex_setup(active_state, myproposal)) != 0)
2175 fatal("kex_setup: %s", ssh_err(r));
2176 kex = active_state->kex;
2178 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2179 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2180 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
2181 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
2182 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
2183 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2184 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2185 # ifdef OPENSSL_HAS_ECC
2186 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2189 kex->kex[KEX_C25519_SHA256] = kexc25519_server;
2191 kex->client_version_string=client_version_string;
2192 kex->server_version_string=server_version_string;
2193 kex->load_host_public_key=&get_hostkey_public_by_type;
2194 kex->load_host_private_key=&get_hostkey_private_by_type;
2195 kex->host_key_index=&get_hostkey_index;
2196 kex->sign = sshd_hostkey_sign;
2198 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done);
2200 session_id2 = kex->session_id;
2201 session_id2_len = kex->session_id_len;
2204 /* send 1st encrypted/maced/compressed message */
2205 packet_start(SSH2_MSG_IGNORE);
2206 packet_put_cstring("markus");
2208 packet_write_wait();
2213 /* server specific fatal cleanup */
2217 struct ssh *ssh = active_state; /* XXX */
2220 do_cleanup(ssh, the_authctxt);
2221 if (use_privsep && privsep_is_preauth &&
2222 pmonitor != NULL && pmonitor->m_pid > 1) {
2223 debug("Killing privsep child %d", pmonitor->m_pid);
2224 if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2226 error("%s: kill(%d): %s", __func__,
2227 pmonitor->m_pid, strerror(errno));
2230 #ifdef SSH_AUDIT_EVENTS
2231 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2232 if (!use_privsep || mm_is_monitor())
2233 audit_event(SSH_CONNECTION_ABANDON);