1 /* $OpenBSD: sshd.c,v 1.514 2018/08/13 02:41:05 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"
122 #include "auth-options.h"
127 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
128 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
129 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
130 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
132 extern char *__progname;
134 /* Server configuration options. */
135 ServerOptions options;
137 /* Name of the server configuration file. */
138 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
141 * Debug mode flag. This can be set on the command line. If debug
142 * mode is enabled, extra debugging output will be sent to the system
143 * log, the daemon will not go to background, and will exit after processing
144 * the first connection.
149 * Indicating that the daemon should only test the configuration and keys.
150 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective
151 * configuration, optionally using connection information provided by the
156 /* Flag indicating that the daemon is being started from inetd. */
159 /* Flag indicating that sshd should not detach and become a daemon. */
160 int no_daemon_flag = 0;
162 /* debug goes to stderr unless inetd_flag is set */
165 /* Saved arguments to main(). */
170 int rexeced_flag = 0;
176 * The sockets that the server is listening; this is used in the SIGHUP
179 #define MAX_LISTEN_SOCKS 16
180 int listen_socks[MAX_LISTEN_SOCKS];
181 int num_listen_socks = 0;
184 * the client's version string, passed by sshd2 in compat mode. if != NULL,
185 * sshd will skip the version-number exchange
187 char *client_version_string = NULL;
188 char *server_version_string = NULL;
190 /* Daemon's agent connection */
195 * Any really sensitive data in the application is contained in this
196 * structure. The idea is that this structure could be locked into memory so
197 * that the pages do not get written into swap. However, there are some
198 * problems. The private key contains BIGNUMs, and we do not (in principle)
199 * have access to the internals of them, and locking just the structure is
200 * not very useful. Currently, memory locking is not implemented.
203 struct sshkey **host_keys; /* all private host keys */
204 struct sshkey **host_pubkeys; /* all public host keys */
205 struct sshkey **host_certificates; /* all public host certificates */
209 /* This is set to true when a signal is received. */
210 static volatile sig_atomic_t received_sighup = 0;
211 static volatile sig_atomic_t received_sigterm = 0;
213 /* session identifier, used by RSA-auth */
214 u_char session_id[16];
217 u_char *session_id2 = NULL;
218 u_int session_id2_len = 0;
220 /* record remote hostname or ip */
221 u_int utmp_len = HOST_NAME_MAX+1;
223 /* options.max_startup sized array of fd ints */
224 int *startup_pipes = NULL;
225 int startup_pipe; /* in child */
227 /* variables used for privilege separation */
228 int use_privsep = -1;
229 struct monitor *pmonitor = NULL;
230 int privsep_is_preauth = 1;
231 static int privsep_chroot = 1;
233 /* global authentication context */
234 Authctxt *the_authctxt = NULL;
236 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */
237 struct sshauthopt *auth_opts = NULL;
239 /* sshd_config buffer */
242 /* message to be displayed after login */
243 struct sshbuf *loginmsg;
245 /* Unprivileged user */
246 struct passwd *privsep_pw = NULL;
248 /* Prototypes for various functions defined later in this file. */
249 void destroy_sensitive_data(void);
250 void demote_sensitive_data(void);
251 static void do_ssh2_kex(void);
254 * Close all listening sockets
257 close_listen_socks(void)
261 for (i = 0; i < num_listen_socks; i++)
262 close(listen_socks[i]);
263 num_listen_socks = -1;
267 close_startup_pipes(void)
272 for (i = 0; i < options.max_startups; i++)
273 if (startup_pipes[i] != -1)
274 close(startup_pipes[i]);
278 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
279 * the effect is to reread the configuration file (and to regenerate
285 sighup_handler(int sig)
287 int save_errno = errno;
294 * Called from the main program after receiving SIGHUP.
295 * Restarts the server.
300 logit("Received SIGHUP; restarting.");
301 if (options.pid_file != NULL)
302 unlink(options.pid_file);
303 platform_pre_restart();
304 close_listen_socks();
305 close_startup_pipes();
306 alarm(0); /* alarm timer persists across exec */
307 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
308 execv(saved_argv[0], saved_argv);
309 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
315 * Generic signal handler for terminating signals in the master daemon.
319 sigterm_handler(int sig)
321 received_sigterm = sig;
325 * SIGCHLD handler. This is called whenever a child dies. This will then
326 * reap any zombies left by exited children.
330 main_sigchld_handler(int sig)
332 int save_errno = errno;
336 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
337 (pid < 0 && errno == EINTR))
343 * Signal handler for the alarm after the login grace period has expired.
347 grace_alarm_handler(int sig)
349 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
350 kill(pmonitor->m_pid, SIGALRM);
353 * Try to kill any processes that we have spawned, E.g. authorized
354 * keys command helpers.
356 if (getpgid(0) == getpid()) {
357 signal(SIGTERM, SIG_IGN);
361 /* Log error and exit. */
362 sigdie("Timeout before authentication for %s port %d",
363 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state));
367 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out)
370 int remote_major, remote_minor;
372 char buf[256]; /* Must not be larger than remote_version. */
373 char remote_version[256]; /* Must be at least as big as buf. */
375 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n",
376 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
377 *options.version_addendum == '\0' ? "" : " ",
378 options.version_addendum);
380 /* Send our protocol version identification. */
381 if (atomicio(vwrite, sock_out, server_version_string,
382 strlen(server_version_string))
383 != strlen(server_version_string)) {
384 logit("Could not write ident string to %s port %d",
385 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
389 /* Read other sides version identification. */
390 memset(buf, 0, sizeof(buf));
391 for (i = 0; i < sizeof(buf) - 1; i++) {
392 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
393 logit("Did not receive identification string "
395 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
398 if (buf[i] == '\r') {
400 /* Kludge for F-Secure Macintosh < 1.0.2 */
402 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
406 if (buf[i] == '\n') {
411 buf[sizeof(buf) - 1] = 0;
412 client_version_string = xstrdup(buf);
415 * Check that the versions match. In future this might accept
416 * several versions and set appropriate flags to handle them.
418 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
419 &remote_major, &remote_minor, remote_version) != 3) {
420 s = "Protocol mismatch.\n";
421 (void) atomicio(vwrite, sock_out, s, strlen(s));
422 logit("Bad protocol version identification '%.100s' "
423 "from %s port %d", client_version_string,
424 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
429 debug("Client protocol version %d.%d; client software version %.100s",
430 remote_major, remote_minor, remote_version);
432 ssh->compat = compat_datafellows(remote_version);
434 if ((ssh->compat & SSH_BUG_PROBE) != 0) {
435 logit("probed 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_SCANNER) != 0) {
441 logit("scanned from %s port %d with %s. Don't panic.",
442 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
443 client_version_string);
446 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
447 logit("Client version \"%.100s\" uses unsafe RSA signature "
448 "scheme; disabling use of RSA keys", remote_version);
451 chop(server_version_string);
452 debug("Local version string %.200s", server_version_string);
454 if (remote_major != 2 &&
455 !(remote_major == 1 && remote_minor == 99)) {
456 s = "Protocol major versions differ.\n";
457 (void) atomicio(vwrite, sock_out, s, strlen(s));
460 logit("Protocol major versions differ for %s port %d: "
462 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
463 server_version_string, client_version_string);
468 /* Destroy the host and server keys. They will no longer be needed. */
470 destroy_sensitive_data(void)
474 for (i = 0; i < options.num_host_key_files; i++) {
475 if (sensitive_data.host_keys[i]) {
476 sshkey_free(sensitive_data.host_keys[i]);
477 sensitive_data.host_keys[i] = NULL;
479 if (sensitive_data.host_certificates[i]) {
480 sshkey_free(sensitive_data.host_certificates[i]);
481 sensitive_data.host_certificates[i] = NULL;
486 /* Demote private to public keys for network child */
488 demote_sensitive_data(void)
494 for (i = 0; i < options.num_host_key_files; i++) {
495 if (sensitive_data.host_keys[i]) {
496 if ((r = sshkey_demote(sensitive_data.host_keys[i],
498 fatal("could not demote host %s key: %s",
499 sshkey_type(sensitive_data.host_keys[i]),
501 sshkey_free(sensitive_data.host_keys[i]);
502 sensitive_data.host_keys[i] = tmp;
504 /* Certs do not need demotion */
516 arc4random_stir(); /* noop on recent arc4random() implementations */
517 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
520 RAND_seed(rnd, sizeof(rnd));
521 /* give libcrypto a chance to notice the PID change */
522 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
523 fatal("%s: RAND_bytes failed", __func__);
526 explicit_bzero(rnd, sizeof(rnd));
530 privsep_preauth_child(void)
534 /* Enable challenge-response authentication for privilege separation */
535 privsep_challenge_enable();
538 /* Cache supported mechanism OIDs for later use */
539 if (options.gss_authentication)
540 ssh_gssapi_prepare_supported_oids();
545 /* Demote the private keys to public keys. */
546 demote_sensitive_data();
548 /* Demote the child */
549 if (privsep_chroot) {
550 /* Change our root directory */
551 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
552 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
554 if (chdir("/") == -1)
555 fatal("chdir(\"/\"): %s", strerror(errno));
557 /* Drop our privileges */
558 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
559 (u_int)privsep_pw->pw_gid);
560 gidset[0] = privsep_pw->pw_gid;
561 if (setgroups(1, gidset) < 0)
562 fatal("setgroups: %.100s", strerror(errno));
563 permanently_set_uid(privsep_pw);
568 privsep_preauth(Authctxt *authctxt)
572 struct ssh_sandbox *box = NULL;
574 /* Set up unprivileged child process to deal with network data */
575 pmonitor = monitor_init();
576 /* Store a pointer to the kex for later rekeying */
577 pmonitor->m_pkex = &active_state->kex;
579 if (use_privsep == PRIVSEP_ON)
580 box = ssh_sandbox_init(pmonitor);
583 fatal("fork of unprivileged child failed");
584 } else if (pid != 0) {
585 debug2("Network child is on pid %ld", (long)pid);
587 pmonitor->m_pid = pid;
589 r = ssh_get_authentication_socket(&auth_sock);
591 error("Could not get agent socket: %s",
597 ssh_sandbox_parent_preauth(box, pid);
598 monitor_child_preauth(authctxt, pmonitor);
600 /* Wait for the child's exit status */
601 while (waitpid(pid, &status, 0) < 0) {
604 pmonitor->m_pid = -1;
605 fatal("%s: waitpid: %s", __func__, strerror(errno));
607 privsep_is_preauth = 0;
608 pmonitor->m_pid = -1;
609 if (WIFEXITED(status)) {
610 if (WEXITSTATUS(status) != 0)
611 fatal("%s: preauth child exited with status %d",
612 __func__, WEXITSTATUS(status));
613 } else if (WIFSIGNALED(status))
614 fatal("%s: preauth child terminated by signal %d",
615 __func__, WTERMSIG(status));
617 ssh_sandbox_parent_finish(box);
621 close(pmonitor->m_sendfd);
622 close(pmonitor->m_log_recvfd);
624 /* Arrange for logging to be sent to the monitor */
625 set_log_handler(mm_log_handler, pmonitor);
627 privsep_preauth_child();
628 setproctitle("%s", "[net]");
630 ssh_sandbox_child(box);
637 privsep_postauth(Authctxt *authctxt)
639 #ifdef DISABLE_FD_PASSING
642 if (authctxt->pw->pw_uid == 0) {
644 /* File descriptor passing is broken or root login */
649 /* New socket pair */
650 monitor_reinit(pmonitor);
652 pmonitor->m_pid = fork();
653 if (pmonitor->m_pid == -1)
654 fatal("fork of unprivileged child failed");
655 else if (pmonitor->m_pid != 0) {
656 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
657 sshbuf_reset(loginmsg);
658 monitor_clear_keystate(pmonitor);
659 monitor_child_postauth(pmonitor);
667 close(pmonitor->m_sendfd);
668 pmonitor->m_sendfd = -1;
670 /* Demote the private keys to public keys. */
671 demote_sensitive_data();
675 /* Drop privileges */
676 do_setusercontext(authctxt->pw);
679 /* It is safe now to apply the key state */
680 monitor_apply_keystate(pmonitor);
683 * Tell the packet layer that authentication was successful, since
684 * this information is not part of the key state.
686 packet_set_authenticated();
690 append_hostkey_type(struct sshbuf *b, const char *s)
694 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
695 debug3("%s: %s key not permitted by HostkeyAlgorithms",
699 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
700 fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r));
704 list_hostkey_types(void)
711 if ((b = sshbuf_new()) == NULL)
712 fatal("%s: sshbuf_new failed", __func__);
713 for (i = 0; i < options.num_host_key_files; i++) {
714 key = sensitive_data.host_keys[i];
716 key = sensitive_data.host_pubkeys[i];
721 /* for RSA we also support SHA2 signatures */
722 append_hostkey_type(b, "rsa-sha2-512");
723 append_hostkey_type(b, "rsa-sha2-256");
729 append_hostkey_type(b, sshkey_ssh_name(key));
732 /* If the private key has a cert peer, then list that too */
733 key = sensitive_data.host_certificates[i];
738 /* for RSA we also support SHA2 signatures */
739 append_hostkey_type(b,
740 "rsa-sha2-512-cert-v01@openssh.com");
741 append_hostkey_type(b,
742 "rsa-sha2-256-cert-v01@openssh.com");
746 case KEY_ED25519_CERT:
748 append_hostkey_type(b, sshkey_ssh_name(key));
752 if ((ret = sshbuf_dup_string(b)) == NULL)
753 fatal("%s: sshbuf_dup_string failed", __func__);
755 debug("%s: %s", __func__, ret);
759 static struct sshkey *
760 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
765 for (i = 0; i < options.num_host_key_files; i++) {
770 case KEY_ED25519_CERT:
772 key = sensitive_data.host_certificates[i];
775 key = sensitive_data.host_keys[i];
776 if (key == NULL && !need_private)
777 key = sensitive_data.host_pubkeys[i];
780 if (key != NULL && key->type == type &&
781 (key->type != KEY_ECDSA || key->ecdsa_nid == nid))
782 return need_private ?
783 sensitive_data.host_keys[i] : key;
789 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
791 return get_hostkey_by_type(type, nid, 0, ssh);
795 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
797 return get_hostkey_by_type(type, nid, 1, ssh);
801 get_hostkey_by_index(int ind)
803 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
805 return (sensitive_data.host_keys[ind]);
809 get_hostkey_public_by_index(int ind, struct ssh *ssh)
811 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
813 return (sensitive_data.host_pubkeys[ind]);
817 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
821 for (i = 0; i < options.num_host_key_files; i++) {
822 if (sshkey_is_cert(key)) {
823 if (key == sensitive_data.host_certificates[i] ||
824 (compare && sensitive_data.host_certificates[i] &&
826 sensitive_data.host_certificates[i])))
829 if (key == sensitive_data.host_keys[i] ||
830 (compare && sensitive_data.host_keys[i] &&
831 sshkey_equal(key, sensitive_data.host_keys[i])))
833 if (key == sensitive_data.host_pubkeys[i] ||
834 (compare && sensitive_data.host_pubkeys[i] &&
835 sshkey_equal(key, sensitive_data.host_pubkeys[i])))
842 /* Inform the client of all hostkeys */
844 notify_hostkeys(struct ssh *ssh)
852 /* Some clients cannot cope with the hostkeys message, skip those. */
853 if (datafellows & SSH_BUG_HOSTKEYS)
856 if ((buf = sshbuf_new()) == NULL)
857 fatal("%s: sshbuf_new", __func__);
858 for (i = nkeys = 0; i < options.num_host_key_files; i++) {
859 key = get_hostkey_public_by_index(i, ssh);
860 if (key == NULL || key->type == KEY_UNSPEC ||
863 fp = sshkey_fingerprint(key, options.fingerprint_hash,
865 debug3("%s: key %d: %s %s", __func__, i,
866 sshkey_ssh_name(key), fp);
869 packet_start(SSH2_MSG_GLOBAL_REQUEST);
870 packet_put_cstring("hostkeys-00@openssh.com");
871 packet_put_char(0); /* want-reply */
874 if ((r = sshkey_putb(key, buf)) != 0)
875 fatal("%s: couldn't put hostkey %d: %s",
876 __func__, i, ssh_err(r));
877 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf));
880 debug3("%s: sent %u hostkeys", __func__, nkeys);
882 fatal("%s: no hostkeys", __func__);
888 * returns 1 if connection should be dropped, 0 otherwise.
889 * dropping starts at connection #max_startups_begin with a probability
890 * of (max_startups_rate/100). the probability increases linearly until
891 * all connections are dropped for startups > max_startups
894 drop_connection(int startups)
898 if (startups < options.max_startups_begin)
900 if (startups >= options.max_startups)
902 if (options.max_startups_rate == 100)
905 p = 100 - options.max_startups_rate;
906 p *= startups - options.max_startups_begin;
907 p /= options.max_startups - options.max_startups_begin;
908 p += options.max_startups_rate;
909 r = arc4random_uniform(100);
911 debug("drop_connection: p %d, r %d", p, r);
912 return (r < p) ? 1 : 0;
918 fprintf(stderr, "%s, %s\n",
921 SSLeay_version(SSLEAY_VERSION)
927 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n"
928 " [-E log_file] [-f config_file] [-g login_grace_time]\n"
929 " [-h host_key_file] [-o option] [-p port] [-u len]\n"
935 send_rexec_state(int fd, struct sshbuf *conf)
940 debug3("%s: entering fd = %d config len %zu", __func__, fd,
944 * Protocol from reexec master to child:
945 * string configuration
946 * string rngseed (only if OpenSSL is not self-seeded)
948 if ((m = sshbuf_new()) == NULL)
949 fatal("%s: sshbuf_new failed", __func__);
950 if ((r = sshbuf_put_stringb(m, conf)) != 0)
951 fatal("%s: buffer error: %s", __func__, ssh_err(r));
953 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
954 rexec_send_rng_seed(m);
957 if (ssh_msg_send(fd, 0, m) == -1)
958 fatal("%s: ssh_msg_send failed", __func__);
962 debug3("%s: done", __func__);
966 recv_rexec_state(int fd, struct sshbuf *conf)
973 debug3("%s: entering fd = %d", __func__, fd);
975 if ((m = sshbuf_new()) == NULL)
976 fatal("%s: sshbuf_new failed", __func__);
977 if (ssh_msg_recv(fd, m) == -1)
978 fatal("%s: ssh_msg_recv failed", __func__);
979 if ((r = sshbuf_get_u8(m, &ver)) != 0)
980 fatal("%s: buffer error: %s", __func__, ssh_err(r));
982 fatal("%s: rexec version mismatch", __func__);
983 if ((r = sshbuf_get_string(m, &cp, &len)) != 0)
984 fatal("%s: buffer error: %s", __func__, ssh_err(r));
985 if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
986 fatal("%s: buffer error: %s", __func__, ssh_err(r));
987 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
988 rexec_recv_rng_seed(m);
994 debug3("%s: done", __func__);
997 /* Accept a connection from inetd */
999 server_accept_inetd(int *sock_in, int *sock_out)
1005 close(REEXEC_CONFIG_PASS_FD);
1006 *sock_in = *sock_out = dup(STDIN_FILENO);
1008 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1009 close(REEXEC_STARTUP_PIPE_FD);
1012 *sock_in = dup(STDIN_FILENO);
1013 *sock_out = dup(STDOUT_FILENO);
1016 * We intentionally do not close the descriptors 0, 1, and 2
1017 * as our code for setting the descriptors won't work if
1018 * ttyfd happens to be one of those.
1020 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1021 dup2(fd, STDIN_FILENO);
1022 dup2(fd, STDOUT_FILENO);
1024 dup2(fd, STDERR_FILENO);
1025 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO))
1028 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1032 * Listen for TCP connections
1035 listen_on_addrs(struct listenaddr *la)
1037 int ret, listen_sock;
1038 struct addrinfo *ai;
1039 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1041 for (ai = la->addrs; ai; ai = ai->ai_next) {
1042 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1044 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1045 fatal("Too many listen sockets. "
1046 "Enlarge MAX_LISTEN_SOCKS");
1047 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1048 ntop, sizeof(ntop), strport, sizeof(strport),
1049 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1050 error("getnameinfo failed: %.100s",
1051 ssh_gai_strerror(ret));
1054 /* Create socket for listening. */
1055 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1057 if (listen_sock < 0) {
1058 /* kernel may not support ipv6 */
1059 verbose("socket: %.100s", strerror(errno));
1062 if (set_nonblock(listen_sock) == -1) {
1066 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
1067 verbose("socket: CLOEXEC: %s", strerror(errno));
1071 /* Socket options */
1072 set_reuseaddr(listen_sock);
1073 if (la->rdomain != NULL &&
1074 set_rdomain(listen_sock, la->rdomain) == -1) {
1079 /* Only communicate in IPv6 over AF_INET6 sockets. */
1080 if (ai->ai_family == AF_INET6)
1081 sock_set_v6only(listen_sock);
1083 debug("Bind to port %s on %s.", strport, ntop);
1085 /* Bind the socket to the desired port. */
1086 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1087 error("Bind to port %s on %s failed: %.200s.",
1088 strport, ntop, strerror(errno));
1092 listen_socks[num_listen_socks] = listen_sock;
1095 /* Start listening on the port. */
1096 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1097 fatal("listen on [%s]:%s: %.100s",
1098 ntop, strport, strerror(errno));
1099 logit("Server listening on %s port %s%s%s.",
1101 la->rdomain == NULL ? "" : " rdomain ",
1102 la->rdomain == NULL ? "" : la->rdomain);
1111 for (i = 0; i < options.num_listen_addrs; i++) {
1112 listen_on_addrs(&options.listen_addrs[i]);
1113 freeaddrinfo(options.listen_addrs[i].addrs);
1114 free(options.listen_addrs[i].rdomain);
1115 memset(&options.listen_addrs[i], 0,
1116 sizeof(options.listen_addrs[i]));
1118 free(options.listen_addrs);
1119 options.listen_addrs = NULL;
1120 options.num_listen_addrs = 0;
1122 if (!num_listen_socks)
1123 fatal("Cannot bind any address.");
1127 * The main TCP accept loop. Note that, for the non-debug case, returns
1128 * from this function are in a forked subprocess.
1131 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1134 int i, j, ret, maxfd;
1136 int startup_p[2] = { -1 , -1 };
1137 struct sockaddr_storage from;
1142 /* setup fd set for accept */
1145 for (i = 0; i < num_listen_socks; i++)
1146 if (listen_socks[i] > maxfd)
1147 maxfd = listen_socks[i];
1148 /* pipes connected to unauthenticated childs */
1149 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1150 for (i = 0; i < options.max_startups; i++)
1151 startup_pipes[i] = -1;
1154 * Stay listening for connections until the system crashes or
1155 * the daemon is killed with a signal.
1158 if (received_sighup)
1161 fdset = xcalloc(howmany(maxfd + 1, NFDBITS),
1164 for (i = 0; i < num_listen_socks; i++)
1165 FD_SET(listen_socks[i], fdset);
1166 for (i = 0; i < options.max_startups; i++)
1167 if (startup_pipes[i] != -1)
1168 FD_SET(startup_pipes[i], fdset);
1170 /* Wait in select until there is a connection. */
1171 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1172 if (ret < 0 && errno != EINTR)
1173 error("select: %.100s", strerror(errno));
1174 if (received_sigterm) {
1175 logit("Received signal %d; terminating.",
1176 (int) received_sigterm);
1177 close_listen_socks();
1178 if (options.pid_file != NULL)
1179 unlink(options.pid_file);
1180 exit(received_sigterm == SIGTERM ? 0 : 255);
1185 for (i = 0; i < options.max_startups; i++)
1186 if (startup_pipes[i] != -1 &&
1187 FD_ISSET(startup_pipes[i], fdset)) {
1189 * the read end of the pipe is ready
1190 * if the child has closed the pipe
1191 * after successful authentication
1192 * or if the child has died
1194 close(startup_pipes[i]);
1195 startup_pipes[i] = -1;
1198 for (i = 0; i < num_listen_socks; i++) {
1199 if (!FD_ISSET(listen_socks[i], fdset))
1201 fromlen = sizeof(from);
1202 *newsock = accept(listen_socks[i],
1203 (struct sockaddr *)&from, &fromlen);
1205 if (errno != EINTR && errno != EWOULDBLOCK &&
1206 errno != ECONNABORTED && errno != EAGAIN)
1207 error("accept: %.100s",
1209 if (errno == EMFILE || errno == ENFILE)
1213 if (unset_nonblock(*newsock) == -1) {
1217 if (drop_connection(startups) == 1) {
1218 char *laddr = get_local_ipaddr(*newsock);
1219 char *raddr = get_peer_ipaddr(*newsock);
1221 verbose("drop connection #%d from [%s]:%d "
1222 "on [%s]:%d past MaxStartups", startups,
1223 raddr, get_peer_port(*newsock),
1224 laddr, get_local_port(*newsock));
1230 if (pipe(startup_p) == -1) {
1235 if (rexec_flag && socketpair(AF_UNIX,
1236 SOCK_STREAM, 0, config_s) == -1) {
1237 error("reexec socketpair: %s",
1240 close(startup_p[0]);
1241 close(startup_p[1]);
1245 for (j = 0; j < options.max_startups; j++)
1246 if (startup_pipes[j] == -1) {
1247 startup_pipes[j] = startup_p[0];
1248 if (maxfd < startup_p[0])
1249 maxfd = startup_p[0];
1255 * Got connection. Fork a child to handle it, unless
1256 * we are in debugging mode.
1260 * In debugging mode. Close the listening
1261 * socket, and start processing the
1262 * connection without forking.
1264 debug("Server will not fork when running in debugging mode.");
1265 close_listen_socks();
1266 *sock_in = *newsock;
1267 *sock_out = *newsock;
1268 close(startup_p[0]);
1269 close(startup_p[1]);
1273 send_rexec_state(config_s[0], cfg);
1280 * Normal production daemon. Fork, and have
1281 * the child process the connection. The
1282 * parent continues listening.
1284 platform_pre_fork();
1285 if ((pid = fork()) == 0) {
1287 * Child. Close the listening and
1288 * max_startup sockets. Start using
1289 * the accepted socket. Reinitialize
1290 * logging (since our pid has changed).
1291 * We break out of the loop to handle
1294 platform_post_fork_child();
1295 startup_pipe = startup_p[1];
1296 close_startup_pipes();
1297 close_listen_socks();
1298 *sock_in = *newsock;
1299 *sock_out = *newsock;
1300 log_init(__progname,
1302 options.log_facility,
1309 /* Parent. Stay in the loop. */
1310 platform_post_fork_parent(pid);
1312 error("fork: %.100s", strerror(errno));
1314 debug("Forked child %ld.", (long)pid);
1316 close(startup_p[1]);
1319 send_rexec_state(config_s[0], cfg);
1326 * Ensure that our random state differs
1327 * from that of the child
1330 arc4random_buf(rnd, sizeof(rnd));
1332 RAND_seed(rnd, sizeof(rnd));
1333 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
1334 fatal("%s: RAND_bytes failed", __func__);
1336 explicit_bzero(rnd, sizeof(rnd));
1339 /* child process check (or debug mode) */
1340 if (num_listen_socks < 0)
1346 * If IP options are supported, make sure there are none (log and
1347 * return an error if any are found). Basically we are worried about
1348 * source routing; it can be used to pretend you are somebody
1349 * (ip-address) you are not. That itself may be "almost acceptable"
1350 * under certain circumstances, but rhosts authentication is useless
1351 * if source routing is accepted. Notice also that if we just dropped
1352 * source routing here, the other side could use IP spoofing to do
1353 * rest of the interaction and could still bypass security. So we
1354 * exit here if we detect any IP options.
1357 check_ip_options(struct ssh *ssh)
1360 int sock_in = ssh_packet_get_connection_in(ssh);
1361 struct sockaddr_storage from;
1363 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
1364 char text[sizeof(opts) * 3 + 1];
1366 memset(&from, 0, sizeof(from));
1367 if (getpeername(sock_in, (struct sockaddr *)&from,
1370 if (from.ss_family != AF_INET)
1372 /* XXX IPv6 options? */
1374 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
1375 &option_size) >= 0 && option_size != 0) {
1377 for (i = 0; i < option_size; i++)
1378 snprintf(text + i*3, sizeof(text) - i*3,
1380 fatal("Connection from %.100s port %d with IP opts: %.800s",
1381 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
1384 #endif /* IP_OPTIONS */
1387 /* Set the routing domain for this process */
1389 set_process_rdomain(struct ssh *ssh, const char *name)
1391 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN)
1393 return; /* default */
1395 if (strcmp(name, "%D") == 0) {
1396 /* "expands" to routing domain of connection */
1397 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
1400 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */
1401 return sys_set_process_rdomain(name);
1402 #elif defined(__OpenBSD__)
1403 int rtable, ortable = getrtable();
1407 return; /* default */
1409 if (strcmp(name, "%D") == 0) {
1410 /* "expands" to routing domain of connection */
1411 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
1415 rtable = (int)strtonum(name, 0, 255, &errstr);
1416 if (errstr != NULL) /* Shouldn't happen */
1417 fatal("Invalid routing domain \"%s\": %s", name, errstr);
1418 if (rtable != ortable && setrtable(rtable) != 0)
1419 fatal("Unable to set routing domain %d: %s",
1420 rtable, strerror(errno));
1421 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable);
1422 #else /* defined(__OpenBSD__) */
1423 fatal("Unable to set routing domain: not supported in this platform");
1428 accumulate_host_timing_secret(struct sshbuf *server_cfg,
1429 const struct sshkey *key)
1431 static struct ssh_digest_ctx *ctx;
1437 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL)
1438 fatal("%s: ssh_digest_start", __func__);
1439 if (key == NULL) { /* finalize */
1440 /* add server config in case we are using agent for host keys */
1441 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg),
1442 sshbuf_len(server_cfg)) != 0)
1443 fatal("%s: ssh_digest_update", __func__);
1444 len = ssh_digest_bytes(SSH_DIGEST_SHA512);
1445 hash = xmalloc(len);
1446 if (ssh_digest_final(ctx, hash, len) != 0)
1447 fatal("%s: ssh_digest_final", __func__);
1448 options.timing_secret = PEEK_U64(hash);
1449 freezero(hash, len);
1450 ssh_digest_free(ctx);
1454 if ((buf = sshbuf_new()) == NULL)
1455 fatal("%s could not allocate buffer", __func__);
1456 if ((r = sshkey_private_serialize(key, buf)) != 0)
1457 fatal("sshkey_private_serialize: %s", ssh_err(r));
1458 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0)
1459 fatal("%s: ssh_digest_update", __func__);
1465 * Main program for the daemon.
1468 main(int ac, char **av)
1470 struct ssh *ssh = NULL;
1471 extern char *optarg;
1473 int r, opt, on = 1, already_daemon, remote_port;
1474 int sock_in = -1, sock_out = -1, newsock = -1;
1475 const char *remote_ip, *rdomain;
1476 char *fp, *line, *laddr, *logfile = NULL;
1477 int config_s[2] = { -1 , -1 };
1479 u_int64_t ibytes, obytes;
1482 struct sshkey *pubkey;
1485 struct connection_info *connection_info = NULL;
1487 ssh_malloc_init(); /* must be called before any mallocs */
1489 #ifdef HAVE_SECUREWARE
1490 (void)set_auth_parameters(ac, av);
1492 __progname = ssh_get_progname(av[0]);
1494 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1497 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1498 for (i = 0; (int)i < ac; i++)
1499 saved_argv[i] = xstrdup(av[i]);
1500 saved_argv[i] = NULL;
1502 #ifndef HAVE_SETPROCTITLE
1503 /* Prepare for later setproctitle emulation */
1504 compat_init_setproctitle(ac, av);
1508 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1509 debug("setgroups(): %.200s", strerror(errno));
1511 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1514 /* Initialize configuration options to their default values. */
1515 initialize_server_options(&options);
1517 /* Parse command-line arguments. */
1518 while ((opt = getopt(ac, av,
1519 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) {
1522 options.address_family = AF_INET;
1525 options.address_family = AF_INET6;
1528 config_file_name = optarg;
1531 servconf_add_hostcert("[command-line]", 0,
1535 if (debug_flag == 0) {
1537 options.log_level = SYSLOG_LEVEL_DEBUG1;
1538 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1539 options.log_level++;
1564 options.log_level = SYSLOG_LEVEL_QUIET;
1567 /* protocol 1, ignored */
1570 options.ports_from_cmdline = 1;
1571 if (options.num_ports >= MAX_PORTS) {
1572 fprintf(stderr, "too many ports.\n");
1575 options.ports[options.num_ports++] = a2port(optarg);
1576 if (options.ports[options.num_ports-1] <= 0) {
1577 fprintf(stderr, "Bad port number.\n");
1582 if ((options.login_grace_time = convtime(optarg)) == -1) {
1583 fprintf(stderr, "Invalid login grace time.\n");
1588 /* protocol 1, ignored */
1591 servconf_add_hostkey("[command-line]", 0,
1601 connection_info = get_connection_info(0, 0);
1602 if (parse_server_match_testspec(connection_info,
1607 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1608 if (utmp_len > HOST_NAME_MAX+1) {
1609 fprintf(stderr, "Invalid utmp length.\n");
1614 line = xstrdup(optarg);
1615 if (process_server_config_line(&options, line,
1616 "command-line", 0, NULL, NULL) != 0)
1626 if (rexeced_flag || inetd_flag)
1628 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1629 fatal("sshd re-exec requires execution with an absolute path");
1631 closefrom(REEXEC_MIN_FREE_FD);
1633 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1636 OpenSSL_add_all_algorithms();
1639 /* If requested, redirect the logs to the specified logfile. */
1640 if (logfile != NULL)
1641 log_redirect_stderr_to(logfile);
1643 * Force logging to stderr until we have loaded the private host
1644 * key (unless started from inetd)
1646 log_init(__progname,
1647 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1648 SYSLOG_LEVEL_INFO : options.log_level,
1649 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1650 SYSLOG_FACILITY_AUTH : options.log_facility,
1651 log_stderr || !inetd_flag);
1654 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1655 * root's environment
1657 if (getenv("KRB5CCNAME") != NULL)
1658 (void) unsetenv("KRB5CCNAME");
1660 sensitive_data.have_ssh2_key = 0;
1663 * If we're not doing an extended test do not silently ignore connection
1666 if (test_flag < 2 && connection_info != NULL)
1667 fatal("Config test connection parameter (-C) provided without "
1670 /* Fetch our configuration */
1671 if ((cfg = sshbuf_new()) == NULL)
1672 fatal("%s: sshbuf_new failed", __func__);
1674 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg);
1675 else if (strcasecmp(config_file_name, "none") != 0)
1676 load_server_config(config_file_name, cfg);
1678 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1683 /* Fill in default values for those options not explicitly set. */
1684 fill_default_server_options(&options);
1686 /* challenge-response is implemented via keyboard interactive */
1687 if (options.challenge_response_authentication)
1688 options.kbd_interactive_authentication = 1;
1690 /* Check that options are sensible */
1691 if (options.authorized_keys_command_user == NULL &&
1692 (options.authorized_keys_command != NULL &&
1693 strcasecmp(options.authorized_keys_command, "none") != 0))
1694 fatal("AuthorizedKeysCommand set without "
1695 "AuthorizedKeysCommandUser");
1696 if (options.authorized_principals_command_user == NULL &&
1697 (options.authorized_principals_command != NULL &&
1698 strcasecmp(options.authorized_principals_command, "none") != 0))
1699 fatal("AuthorizedPrincipalsCommand set without "
1700 "AuthorizedPrincipalsCommandUser");
1703 * Check whether there is any path through configured auth methods.
1704 * Unfortunately it is not possible to verify this generally before
1705 * daemonisation in the presence of Match block, but this catches
1706 * and warns for trivial misconfigurations that could break login.
1708 if (options.num_auth_methods != 0) {
1709 for (i = 0; i < options.num_auth_methods; i++) {
1710 if (auth2_methods_valid(options.auth_methods[i],
1714 if (i >= options.num_auth_methods)
1715 fatal("AuthenticationMethods cannot be satisfied by "
1716 "enabled authentication methods");
1719 /* Check that there are no remaining arguments. */
1721 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1725 debug("sshd version %s, %s", SSH_VERSION,
1727 SSLeay_version(SSLEAY_VERSION)
1733 /* Store privilege separation user for later use if required. */
1734 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0);
1735 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1736 if (privsep_chroot || options.kerberos_authentication)
1737 fatal("Privilege separation user %s does not exist",
1740 privsep_pw = pwcopy(privsep_pw);
1741 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd));
1742 privsep_pw->pw_passwd = xstrdup("*");
1746 /* load host keys */
1747 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1748 sizeof(struct sshkey *));
1749 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1750 sizeof(struct sshkey *));
1752 if (options.host_key_agent) {
1753 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1754 setenv(SSH_AUTHSOCKET_ENV_NAME,
1755 options.host_key_agent, 1);
1756 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1759 error("Could not connect to agent \"%s\": %s",
1760 options.host_key_agent, ssh_err(r));
1763 for (i = 0; i < options.num_host_key_files; i++) {
1764 if (options.host_key_files[i] == NULL)
1766 if ((r = sshkey_load_private(options.host_key_files[i], "",
1767 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1768 error("Error loading host key \"%s\": %s",
1769 options.host_key_files[i], ssh_err(r));
1770 if ((r = sshkey_load_public(options.host_key_files[i],
1771 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1772 error("Error loading host key \"%s\": %s",
1773 options.host_key_files[i], ssh_err(r));
1774 if (pubkey == NULL && key != NULL)
1775 if ((r = sshkey_demote(key, &pubkey)) != 0)
1776 fatal("Could not demote key: \"%s\": %s",
1777 options.host_key_files[i], ssh_err(r));
1778 sensitive_data.host_keys[i] = key;
1779 sensitive_data.host_pubkeys[i] = pubkey;
1781 if (key == NULL && pubkey != NULL && have_agent) {
1782 debug("will rely on agent for hostkey %s",
1783 options.host_key_files[i]);
1784 keytype = pubkey->type;
1785 } else if (key != NULL) {
1786 keytype = key->type;
1787 accumulate_host_timing_secret(cfg, key);
1789 error("Could not load host key: %s",
1790 options.host_key_files[i]);
1791 sensitive_data.host_keys[i] = NULL;
1792 sensitive_data.host_pubkeys[i] = NULL;
1802 if (have_agent || key != NULL)
1803 sensitive_data.have_ssh2_key = 1;
1806 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
1807 SSH_FP_DEFAULT)) == NULL)
1808 fatal("sshkey_fingerprint failed");
1809 debug("%s host key #%d: %s %s",
1810 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
1813 accumulate_host_timing_secret(cfg, NULL);
1814 if (!sensitive_data.have_ssh2_key) {
1815 logit("sshd: no hostkeys available -- exiting.");
1820 * Load certificates. They are stored in an array at identical
1821 * indices to the public keys that they relate to.
1823 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1824 sizeof(struct sshkey *));
1825 for (i = 0; i < options.num_host_key_files; i++)
1826 sensitive_data.host_certificates[i] = NULL;
1828 for (i = 0; i < options.num_host_cert_files; i++) {
1829 if (options.host_cert_files[i] == NULL)
1831 if ((r = sshkey_load_public(options.host_cert_files[i],
1832 &key, NULL)) != 0) {
1833 error("Could not load host certificate \"%s\": %s",
1834 options.host_cert_files[i], ssh_err(r));
1837 if (!sshkey_is_cert(key)) {
1838 error("Certificate file is not a certificate: %s",
1839 options.host_cert_files[i]);
1843 /* Find matching private key */
1844 for (j = 0; j < options.num_host_key_files; j++) {
1845 if (sshkey_equal_public(key,
1846 sensitive_data.host_keys[j])) {
1847 sensitive_data.host_certificates[j] = key;
1851 if (j >= options.num_host_key_files) {
1852 error("No matching private key for certificate: %s",
1853 options.host_cert_files[i]);
1857 sensitive_data.host_certificates[j] = key;
1858 debug("host certificate: #%u type %d %s", j, key->type,
1862 if (privsep_chroot) {
1865 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1866 (S_ISDIR(st.st_mode) == 0))
1867 fatal("Missing privilege separation directory: %s",
1868 _PATH_PRIVSEP_CHROOT_DIR);
1871 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1872 (st.st_uid != getuid () ||
1873 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1875 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1877 fatal("%s must be owned by root and not group or "
1878 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1881 if (test_flag > 1) {
1883 * If no connection info was provided by -C then use
1884 * use a blank one that will cause no predicate to match.
1886 if (connection_info == NULL)
1887 connection_info = get_connection_info(0, 0);
1888 parse_server_match_config(&options, connection_info);
1889 dump_config(&options);
1892 /* Configuration looks good, so exit if in test mode. */
1897 * Clear out any supplemental groups we may have inherited. This
1898 * prevents inadvertent creation of files with bad modes (in the
1899 * portable version at least, it's certainly possible for PAM
1900 * to create a file, and we can't control the code in every
1901 * module which might be used).
1903 if (setgroups(0, NULL) < 0)
1904 debug("setgroups() failed: %.200s", strerror(errno));
1908 fatal("rexec_argc %d < 0", rexec_argc);
1909 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1910 for (i = 0; i < (u_int)rexec_argc; i++) {
1911 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1912 rexec_argv[i] = saved_argv[i];
1914 rexec_argv[rexec_argc] = "-R";
1915 rexec_argv[rexec_argc + 1] = NULL;
1918 /* Ensure that umask disallows at least group and world write */
1919 new_umask = umask(0077) | 0022;
1920 (void) umask(new_umask);
1922 /* Initialize the log (it is reinitialized below in case we forked). */
1923 if (debug_flag && (!inetd_flag || rexeced_flag))
1925 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1928 * If not in debugging mode, not started from inetd and not already
1929 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
1930 * terminal, and fork. The original process exits.
1932 already_daemon = daemonized();
1933 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
1935 if (daemon(0, 0) < 0)
1936 fatal("daemon() failed: %.200s", strerror(errno));
1938 disconnect_controlling_tty();
1940 /* Reinitialize the log (because of the fork above). */
1941 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1943 /* Chdir to the root directory so that the current disk can be
1944 unmounted if desired. */
1945 if (chdir("/") == -1)
1946 error("chdir(\"/\"): %s", strerror(errno));
1948 /* ignore SIGPIPE */
1949 signal(SIGPIPE, SIG_IGN);
1951 /* Get a connection, either from inetd or a listening TCP socket */
1953 server_accept_inetd(&sock_in, &sock_out);
1955 platform_pre_listen();
1958 signal(SIGHUP, sighup_handler);
1959 signal(SIGCHLD, main_sigchld_handler);
1960 signal(SIGTERM, sigterm_handler);
1961 signal(SIGQUIT, sigterm_handler);
1964 * Write out the pid file after the sigterm handler
1965 * is setup and the listen sockets are bound
1967 if (options.pid_file != NULL && !debug_flag) {
1968 FILE *f = fopen(options.pid_file, "w");
1971 error("Couldn't create pid file \"%s\": %s",
1972 options.pid_file, strerror(errno));
1974 fprintf(f, "%ld\n", (long) getpid());
1979 /* Accept a connection and return in a forked child */
1980 server_accept_loop(&sock_in, &sock_out,
1981 &newsock, config_s);
1984 /* This is the child processing a new connection. */
1985 setproctitle("%s", "[accepted]");
1988 * Create a new session and process group since the 4.4BSD
1989 * setlogin() affects the entire process group. We don't
1990 * want the child to be able to affect the parent.
1992 #if !defined(SSHD_ACQUIRES_CTTY)
1994 * If setsid is called, on some platforms sshd will later acquire a
1995 * controlling terminal which will result in "could not set
1996 * controlling tty" errors.
1998 if (!debug_flag && !inetd_flag && setsid() < 0)
1999 error("setsid: %.100s", strerror(errno));
2005 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
2006 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2007 dup2(newsock, STDIN_FILENO);
2008 dup2(STDIN_FILENO, STDOUT_FILENO);
2009 if (startup_pipe == -1)
2010 close(REEXEC_STARTUP_PIPE_FD);
2011 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
2012 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
2013 close(startup_pipe);
2014 startup_pipe = REEXEC_STARTUP_PIPE_FD;
2017 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
2020 execv(rexec_argv[0], rexec_argv);
2022 /* Reexec has failed, fall back and continue */
2023 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
2024 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
2025 log_init(__progname, options.log_level,
2026 options.log_facility, log_stderr);
2029 close(REEXEC_CONFIG_PASS_FD);
2030 newsock = sock_out = sock_in = dup(STDIN_FILENO);
2031 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
2032 dup2(fd, STDIN_FILENO);
2033 dup2(fd, STDOUT_FILENO);
2034 if (fd > STDERR_FILENO)
2037 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
2038 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2041 /* Executed child processes don't need these. */
2042 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
2043 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
2046 * Disable the key regeneration alarm. We will not regenerate the
2047 * key since we are no longer in a position to give it to anyone. We
2048 * will not restart on SIGHUP since it no longer makes sense.
2051 signal(SIGALRM, SIG_DFL);
2052 signal(SIGHUP, SIG_DFL);
2053 signal(SIGTERM, SIG_DFL);
2054 signal(SIGQUIT, SIG_DFL);
2055 signal(SIGCHLD, SIG_DFL);
2056 signal(SIGINT, SIG_DFL);
2059 * Register our connection. This turns encryption off because we do
2062 packet_set_connection(sock_in, sock_out);
2063 packet_set_server();
2064 ssh = active_state; /* XXX */
2066 check_ip_options(ssh);
2068 /* Prepare the channels layer */
2069 channel_init_channels(ssh);
2070 channel_set_af(ssh, options.address_family);
2071 process_permitopen(ssh, &options);
2073 /* Set SO_KEEPALIVE if requested. */
2074 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
2075 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
2076 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
2078 if ((remote_port = ssh_remote_port(ssh)) < 0) {
2079 debug("ssh_remote_port failed");
2083 if (options.routing_domain != NULL)
2084 set_process_rdomain(ssh, options.routing_domain);
2087 * The rest of the code depends on the fact that
2088 * ssh_remote_ipaddr() caches the remote ip, even if
2089 * the socket goes away.
2091 remote_ip = ssh_remote_ipaddr(ssh);
2093 #ifdef SSH_AUDIT_EVENTS
2094 audit_connection_from(remote_ip, remote_port);
2097 rdomain = ssh_packet_rdomain_in(ssh);
2099 /* Log the connection. */
2100 laddr = get_local_ipaddr(sock_in);
2101 verbose("Connection from %s port %d on %s port %d%s%s%s",
2102 remote_ip, remote_port, laddr, ssh_local_port(ssh),
2103 rdomain == NULL ? "" : " rdomain \"",
2104 rdomain == NULL ? "" : rdomain,
2105 rdomain == NULL ? "" : "\"");
2109 * We don't want to listen forever unless the other side
2110 * successfully authenticates itself. So we set up an alarm which is
2111 * cleared after successful authentication. A limit of zero
2112 * indicates no limit. Note that we don't set the alarm in debugging
2113 * mode; it is just annoying to have the server exit just when you
2114 * are about to discover the bug.
2116 signal(SIGALRM, grace_alarm_handler);
2118 alarm(options.login_grace_time);
2120 sshd_exchange_identification(ssh, sock_in, sock_out);
2121 packet_set_nonblocking();
2123 /* allocate authentication context */
2124 authctxt = xcalloc(1, sizeof(*authctxt));
2126 authctxt->loginmsg = loginmsg;
2128 /* XXX global for cleanup, access from other modules */
2129 the_authctxt = authctxt;
2131 /* Set default key authentication options */
2132 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL)
2133 fatal("allocation failed");
2135 /* prepare buffer to collect messages to display to user after login */
2136 if ((loginmsg = sshbuf_new()) == NULL)
2137 fatal("%s: sshbuf_new failed", __func__);
2141 if (privsep_preauth(authctxt) == 1)
2143 } else if (have_agent) {
2144 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
2145 error("Unable to get agent socket: %s", ssh_err(r));
2150 /* perform the key exchange */
2151 /* authenticate user and start session */
2153 do_authentication2(authctxt);
2156 * If we use privilege separation, the unprivileged child transfers
2157 * the current keystate and exits
2160 mm_send_keystate(pmonitor);
2161 packet_clear_keys();
2167 * Cancel the alarm we set to limit the time taken for
2171 signal(SIGALRM, SIG_DFL);
2172 authctxt->authenticated = 1;
2173 if (startup_pipe != -1) {
2174 close(startup_pipe);
2178 #ifdef SSH_AUDIT_EVENTS
2179 audit_event(SSH_AUTH_SUCCESS);
2183 if (options.gss_authentication) {
2184 temporarily_use_uid(authctxt->pw);
2185 ssh_gssapi_storecreds();
2190 if (options.use_pam) {
2192 do_pam_session(ssh);
2197 * In privilege separation, we fork another child and prepare
2198 * file descriptor passing.
2201 privsep_postauth(authctxt);
2202 /* the monitor process [priv] will not return */
2205 packet_set_timeout(options.client_alive_interval,
2206 options.client_alive_count_max);
2208 /* Try to send all our hostkeys to the client */
2209 notify_hostkeys(ssh);
2211 /* Start session. */
2212 do_authenticated(ssh, authctxt);
2214 /* The connection has been terminated. */
2215 packet_get_bytes(&ibytes, &obytes);
2216 verbose("Transferred: sent %llu, received %llu bytes",
2217 (unsigned long long)obytes, (unsigned long long)ibytes);
2219 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2222 if (options.use_pam)
2224 #endif /* USE_PAM */
2226 #ifdef SSH_AUDIT_EVENTS
2227 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2239 sshd_hostkey_sign(struct sshkey *privkey, struct sshkey *pubkey,
2240 u_char **signature, size_t *slenp, const u_char *data, size_t dlen,
2241 const char *alg, u_int flag)
2246 if (PRIVSEP(sshkey_sign(privkey, signature, slenp, data, dlen,
2247 alg, datafellows)) < 0)
2248 fatal("%s: key_sign failed", __func__);
2249 } else if (use_privsep) {
2250 if (mm_sshkey_sign(pubkey, signature, slenp, data, dlen,
2251 alg, datafellows) < 0)
2252 fatal("%s: pubkey_sign failed", __func__);
2254 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slenp,
2255 data, dlen, alg, datafellows)) != 0)
2256 fatal("%s: ssh_agent_sign failed: %s",
2257 __func__, ssh_err(r));
2262 /* SSH2 key exchange */
2266 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
2270 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
2271 options.kex_algorithms);
2272 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
2274 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
2276 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2277 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2279 if (options.compression == COMP_NONE) {
2280 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2281 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2284 if (options.rekey_limit || options.rekey_interval)
2285 packet_set_rekey_limits(options.rekey_limit,
2286 options.rekey_interval);
2288 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
2289 list_hostkey_types());
2291 /* start key exchange */
2292 if ((r = kex_setup(active_state, myproposal)) != 0)
2293 fatal("kex_setup: %s", ssh_err(r));
2294 kex = active_state->kex;
2296 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2297 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2298 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
2299 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
2300 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
2301 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2302 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2303 # ifdef OPENSSL_HAS_ECC
2304 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2307 kex->kex[KEX_C25519_SHA256] = kexc25519_server;
2309 kex->client_version_string=client_version_string;
2310 kex->server_version_string=server_version_string;
2311 kex->load_host_public_key=&get_hostkey_public_by_type;
2312 kex->load_host_private_key=&get_hostkey_private_by_type;
2313 kex->host_key_index=&get_hostkey_index;
2314 kex->sign = sshd_hostkey_sign;
2316 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done);
2318 session_id2 = kex->session_id;
2319 session_id2_len = kex->session_id_len;
2322 /* send 1st encrypted/maced/compressed message */
2323 packet_start(SSH2_MSG_IGNORE);
2324 packet_put_cstring("markus");
2326 packet_write_wait();
2331 /* server specific fatal cleanup */
2335 struct ssh *ssh = active_state; /* XXX */
2338 do_cleanup(ssh, the_authctxt);
2339 if (use_privsep && privsep_is_preauth &&
2340 pmonitor != NULL && pmonitor->m_pid > 1) {
2341 debug("Killing privsep child %d", pmonitor->m_pid);
2342 if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2344 error("%s: kill(%d): %s", __func__,
2345 pmonitor->m_pid, strerror(errno));
2348 #ifdef SSH_AUDIT_EVENTS
2349 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2350 if (!use_privsep || mm_is_monitor())
2351 audit_event(SSH_CONNECTION_ABANDON);