1 /* $OpenBSD: sshd.c,v 1.385 2011/06/23 09:34:13 djm Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This program is the ssh daemon. It listens for connections from clients,
7 * and performs authentication, executes use commands or shell, and forwards
8 * information to/from the application to the user client over an encrypted
9 * connection. This can also handle forwarding of X11, TCP/IP, and
10 * authentication agent connections.
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
18 * SSH2 implementation:
19 * Privilege Separation:
21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22 * Copyright (c) 2002 Niels Provos. All rights reserved.
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
47 #include <sys/types.h>
48 #include <sys/ioctl.h>
49 #include <sys/socket.h>
50 #ifdef HAVE_SYS_STAT_H
51 # include <sys/stat.h>
53 #ifdef HAVE_SYS_TIME_H
54 # include <sys/time.h>
56 #include "openbsd-compat/sys-tree.h"
57 #include "openbsd-compat/sys-queue.h"
75 #include <openssl/dh.h>
76 #include <openssl/bn.h>
77 #include <openssl/md5.h>
78 #include <openssl/rand.h>
79 #include "openbsd-compat/openssl-compat.h"
81 #ifdef HAVE_SECUREWARE
82 #include <sys/security.h>
103 #include "myproposal.h"
104 #include "authfile.h"
105 #include "pathnames.h"
106 #include "atomicio.h"
107 #include "canohost.h"
108 #include "hostfile.h"
112 #include "dispatch.h"
113 #include "channels.h"
115 #include "monitor_mm.h"
120 #include "monitor_wrap.h"
122 #include "ssh-sandbox.h"
137 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
138 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
139 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
140 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
145 extern char *__progname;
147 /* Server configuration options. */
148 ServerOptions options;
150 /* Name of the server configuration file. */
151 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
154 * Debug mode flag. This can be set on the command line. If debug
155 * mode is enabled, extra debugging output will be sent to the system
156 * log, the daemon will not go to background, and will exit after processing
157 * the first connection.
161 /* Flag indicating that the daemon should only test the configuration and keys. */
164 /* Flag indicating that the daemon is being started from inetd. */
167 /* Flag indicating that sshd should not detach and become a daemon. */
168 int no_daemon_flag = 0;
170 /* debug goes to stderr unless inetd_flag is set */
173 /* Saved arguments to main(). */
178 int rexeced_flag = 0;
184 * The sockets that the server is listening; this is used in the SIGHUP
187 #define MAX_LISTEN_SOCKS 16
188 int listen_socks[MAX_LISTEN_SOCKS];
189 int num_listen_socks = 0;
192 * the client's version string, passed by sshd2 in compat mode. if != NULL,
193 * sshd will skip the version-number exchange
195 char *client_version_string = NULL;
196 char *server_version_string = NULL;
198 /* for rekeying XXX fixme */
202 * Any really sensitive data in the application is contained in this
203 * structure. The idea is that this structure could be locked into memory so
204 * that the pages do not get written into swap. However, there are some
205 * problems. The private key contains BIGNUMs, and we do not (in principle)
206 * have access to the internals of them, and locking just the structure is
207 * not very useful. Currently, memory locking is not implemented.
210 Key *server_key; /* ephemeral server key */
211 Key *ssh1_host_key; /* ssh1 host key */
212 Key **host_keys; /* all private host keys */
213 Key **host_certificates; /* all public host certificates */
216 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
220 * Flag indicating whether the RSA server key needs to be regenerated.
221 * Is set in the SIGALRM handler and cleared when the key is regenerated.
223 static volatile sig_atomic_t key_do_regen = 0;
225 /* This is set to true when a signal is received. */
226 static volatile sig_atomic_t received_sighup = 0;
227 static volatile sig_atomic_t received_sigterm = 0;
229 /* session identifier, used by RSA-auth */
230 u_char session_id[16];
233 u_char *session_id2 = NULL;
234 u_int session_id2_len = 0;
236 /* record remote hostname or ip */
237 u_int utmp_len = MAXHOSTNAMELEN;
239 /* options.max_startup sized array of fd ints */
240 int *startup_pipes = NULL;
241 int startup_pipe; /* in child */
243 /* variables used for privilege separation */
244 int use_privsep = -1;
245 struct monitor *pmonitor = NULL;
247 /* global authentication context */
248 Authctxt *the_authctxt = NULL;
250 /* sshd_config buffer */
253 /* message to be displayed after login */
256 /* Unprivileged user */
257 struct passwd *privsep_pw = NULL;
259 /* Prototypes for various functions defined later in this file. */
260 void destroy_sensitive_data(void);
261 void demote_sensitive_data(void);
263 static void do_ssh1_kex(void);
264 static void do_ssh2_kex(void);
267 * Close all listening sockets
270 close_listen_socks(void)
274 for (i = 0; i < num_listen_socks; i++)
275 close(listen_socks[i]);
276 num_listen_socks = -1;
280 close_startup_pipes(void)
285 for (i = 0; i < options.max_startups; i++)
286 if (startup_pipes[i] != -1)
287 close(startup_pipes[i]);
291 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
292 * the effect is to reread the configuration file (and to regenerate
298 sighup_handler(int sig)
300 int save_errno = errno;
303 signal(SIGHUP, sighup_handler);
308 * Called from the main program after receiving SIGHUP.
309 * Restarts the server.
314 logit("Received SIGHUP; restarting.");
315 close_listen_socks();
316 close_startup_pipes();
317 alarm(0); /* alarm timer persists across exec */
318 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
319 execv(saved_argv[0], saved_argv);
320 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
326 * Generic signal handler for terminating signals in the master daemon.
330 sigterm_handler(int sig)
332 received_sigterm = sig;
336 * SIGCHLD handler. This is called whenever a child dies. This will then
337 * reap any zombies left by exited children.
341 main_sigchld_handler(int sig)
343 int save_errno = errno;
347 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
348 (pid < 0 && errno == EINTR))
351 signal(SIGCHLD, main_sigchld_handler);
356 * Signal handler for the alarm after the login grace period has expired.
360 grace_alarm_handler(int sig)
362 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
363 kill(pmonitor->m_pid, SIGALRM);
365 /* Log error and exit. */
366 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
370 * Signal handler for the key regeneration alarm. Note that this
371 * alarm only occurs in the daemon waiting for connections, and it does not
372 * do anything with the private key or random state before forking.
373 * Thus there should be no concurrency control/asynchronous execution
377 generate_ephemeral_server_key(void)
379 verbose("Generating %s%d bit RSA key.",
380 sensitive_data.server_key ? "new " : "", options.server_key_bits);
381 if (sensitive_data.server_key != NULL)
382 key_free(sensitive_data.server_key);
383 sensitive_data.server_key = key_generate(KEY_RSA1,
384 options.server_key_bits);
385 verbose("RSA key generation complete.");
387 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
393 key_regeneration_alarm(int sig)
395 int save_errno = errno;
397 signal(SIGALRM, SIG_DFL);
403 sshd_exchange_identification(int sock_in, int sock_out)
407 int remote_major, remote_minor;
409 char *s, *newline = "\n";
410 char buf[256]; /* Must not be larger than remote_version. */
411 char remote_version[256]; /* Must be at least as big as buf. */
413 if ((options.protocol & SSH_PROTO_1) &&
414 (options.protocol & SSH_PROTO_2)) {
415 major = PROTOCOL_MAJOR_1;
417 } else if (options.protocol & SSH_PROTO_2) {
418 major = PROTOCOL_MAJOR_2;
419 minor = PROTOCOL_MINOR_2;
422 major = PROTOCOL_MAJOR_1;
423 minor = PROTOCOL_MINOR_1;
425 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
426 SSH_RELEASE, newline);
427 server_version_string = xstrdup(buf);
429 /* Send our protocol version identification. */
430 if (roaming_atomicio(vwrite, sock_out, server_version_string,
431 strlen(server_version_string))
432 != strlen(server_version_string)) {
433 logit("Could not write ident string to %s", get_remote_ipaddr());
437 /* Read other sides version identification. */
438 memset(buf, 0, sizeof(buf));
439 for (i = 0; i < sizeof(buf) - 1; i++) {
440 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
441 logit("Did not receive identification string from %s",
442 get_remote_ipaddr());
445 if (buf[i] == '\r') {
447 /* Kludge for F-Secure Macintosh < 1.0.2 */
449 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
453 if (buf[i] == '\n') {
458 buf[sizeof(buf) - 1] = 0;
459 client_version_string = xstrdup(buf);
462 * Check that the versions match. In future this might accept
463 * several versions and set appropriate flags to handle them.
465 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
466 &remote_major, &remote_minor, remote_version) != 3) {
467 s = "Protocol mismatch.\n";
468 (void) atomicio(vwrite, sock_out, s, strlen(s));
471 logit("Bad protocol version identification '%.100s' from %s",
472 client_version_string, get_remote_ipaddr());
475 debug("Client protocol version %d.%d; client software version %.100s",
476 remote_major, remote_minor, remote_version);
477 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s",
478 get_remote_ipaddr(), get_remote_port(),
479 remote_major, remote_minor, remote_version);
481 compat_datafellows(remote_version);
483 if (datafellows & SSH_BUG_PROBE) {
484 logit("probed from %s with %s. Don't panic.",
485 get_remote_ipaddr(), client_version_string);
489 if (datafellows & SSH_BUG_SCANNER) {
490 logit("scanned from %s with %s. Don't panic.",
491 get_remote_ipaddr(), client_version_string);
496 switch (remote_major) {
498 if (remote_minor == 99) {
499 if (options.protocol & SSH_PROTO_2)
505 if (!(options.protocol & SSH_PROTO_1)) {
509 if (remote_minor < 3) {
510 packet_disconnect("Your ssh version is too old and "
511 "is no longer supported. Please install a newer version.");
512 } else if (remote_minor == 3) {
513 /* note that this disables agent-forwarding */
518 if (options.protocol & SSH_PROTO_2) {
527 chop(server_version_string);
528 debug("Local version string %.200s", server_version_string);
531 s = "Protocol major versions differ.\n";
532 (void) atomicio(vwrite, sock_out, s, strlen(s));
535 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
537 server_version_string, client_version_string);
542 /* Destroy the host and server keys. They will no longer be needed. */
544 destroy_sensitive_data(void)
548 if (sensitive_data.server_key) {
549 key_free(sensitive_data.server_key);
550 sensitive_data.server_key = NULL;
552 for (i = 0; i < options.num_host_key_files; i++) {
553 if (sensitive_data.host_keys[i]) {
554 key_free(sensitive_data.host_keys[i]);
555 sensitive_data.host_keys[i] = NULL;
557 if (sensitive_data.host_certificates[i]) {
558 key_free(sensitive_data.host_certificates[i]);
559 sensitive_data.host_certificates[i] = NULL;
562 sensitive_data.ssh1_host_key = NULL;
563 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
566 /* Demote private to public keys for network child */
568 demote_sensitive_data(void)
573 if (sensitive_data.server_key) {
574 tmp = key_demote(sensitive_data.server_key);
575 key_free(sensitive_data.server_key);
576 sensitive_data.server_key = tmp;
579 for (i = 0; i < options.num_host_key_files; i++) {
580 if (sensitive_data.host_keys[i]) {
581 tmp = key_demote(sensitive_data.host_keys[i]);
582 key_free(sensitive_data.host_keys[i]);
583 sensitive_data.host_keys[i] = tmp;
584 if (tmp->type == KEY_RSA1)
585 sensitive_data.ssh1_host_key = tmp;
587 /* Certs do not need demotion */
590 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
594 privsep_preauth_child(void)
599 /* Enable challenge-response authentication for privilege separation */
600 privsep_challenge_enable();
603 arc4random_buf(rnd, sizeof(rnd));
604 RAND_seed(rnd, sizeof(rnd));
606 /* Demote the private keys to public keys. */
607 demote_sensitive_data();
609 /* Change our root directory */
610 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
611 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
613 if (chdir("/") == -1)
614 fatal("chdir(\"/\"): %s", strerror(errno));
616 /* Drop our privileges */
617 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
618 (u_int)privsep_pw->pw_gid);
620 /* XXX not ready, too heavy after chroot */
621 do_setusercontext(privsep_pw);
623 gidset[0] = privsep_pw->pw_gid;
624 if (setgroups(1, gidset) < 0)
625 fatal("setgroups: %.100s", strerror(errno));
626 permanently_set_uid(privsep_pw);
631 privsep_preauth(Authctxt *authctxt)
635 struct ssh_sandbox *box = NULL;
637 /* Set up unprivileged child process to deal with network data */
638 pmonitor = monitor_init();
639 /* Store a pointer to the kex for later rekeying */
640 pmonitor->m_pkex = &xxx_kex;
642 if (use_privsep == PRIVSEP_SANDBOX)
643 box = ssh_sandbox_init();
646 fatal("fork of unprivileged child failed");
647 } else if (pid != 0) {
648 debug2("Network child is on pid %ld", (long)pid);
651 ssh_sandbox_parent_preauth(box, pid);
652 pmonitor->m_pid = pid;
653 monitor_child_preauth(authctxt, pmonitor);
656 monitor_sync(pmonitor);
658 /* Wait for the child's exit status */
659 while (waitpid(pid, &status, 0) < 0) {
661 fatal("%s: waitpid: %s", __func__,
664 if (WIFEXITED(status)) {
665 if (WEXITSTATUS(status) != 0)
666 fatal("%s: preauth child exited with status %d",
667 __func__, WEXITSTATUS(status));
668 } else if (WIFSIGNALED(status))
669 fatal("%s: preauth child terminated by signal %d",
670 __func__, WTERMSIG(status));
672 ssh_sandbox_parent_finish(box);
676 close(pmonitor->m_sendfd);
677 close(pmonitor->m_log_recvfd);
679 /* Arrange for logging to be sent to the monitor */
680 set_log_handler(mm_log_handler, pmonitor);
682 /* Demote the child */
683 if (getuid() == 0 || geteuid() == 0)
684 privsep_preauth_child();
685 setproctitle("%s", "[net]");
687 ssh_sandbox_child(box);
694 privsep_postauth(Authctxt *authctxt)
698 #ifdef DISABLE_FD_PASSING
701 if (authctxt->pw->pw_uid == 0 || options.use_login) {
703 /* File descriptor passing is broken or root login */
708 /* New socket pair */
709 monitor_reinit(pmonitor);
711 pmonitor->m_pid = fork();
712 if (pmonitor->m_pid == -1)
713 fatal("fork of unprivileged child failed");
714 else if (pmonitor->m_pid != 0) {
715 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
716 buffer_clear(&loginmsg);
717 monitor_child_postauth(pmonitor);
725 close(pmonitor->m_sendfd);
726 pmonitor->m_sendfd = -1;
728 /* Demote the private keys to public keys. */
729 demote_sensitive_data();
732 arc4random_buf(rnd, sizeof(rnd));
733 RAND_seed(rnd, sizeof(rnd));
735 /* Drop privileges */
736 do_setusercontext(authctxt->pw);
739 /* It is safe now to apply the key state */
740 monitor_apply_keystate(pmonitor);
743 * Tell the packet layer that authentication was successful, since
744 * this information is not part of the key state.
746 packet_set_authenticated();
750 list_hostkey_types(void)
759 for (i = 0; i < options.num_host_key_files; i++) {
760 key = sensitive_data.host_keys[i];
767 if (buffer_len(&b) > 0)
768 buffer_append(&b, ",", 1);
769 p = key_ssh_name(key);
770 buffer_append(&b, p, strlen(p));
773 /* If the private key has a cert peer, then list that too */
774 key = sensitive_data.host_certificates[i];
778 case KEY_RSA_CERT_V00:
779 case KEY_DSA_CERT_V00:
783 if (buffer_len(&b) > 0)
784 buffer_append(&b, ",", 1);
785 p = key_ssh_name(key);
786 buffer_append(&b, p, strlen(p));
790 buffer_append(&b, "\0", 1);
791 ret = xstrdup(buffer_ptr(&b));
793 debug("list_hostkey_types: %s", ret);
798 get_hostkey_by_type(int type, int need_private)
803 for (i = 0; i < options.num_host_key_files; i++) {
805 case KEY_RSA_CERT_V00:
806 case KEY_DSA_CERT_V00:
810 key = sensitive_data.host_certificates[i];
813 key = sensitive_data.host_keys[i];
816 if (key != NULL && key->type == type)
817 return need_private ?
818 sensitive_data.host_keys[i] : key;
824 get_hostkey_public_by_type(int type)
826 return get_hostkey_by_type(type, 0);
830 get_hostkey_private_by_type(int type)
832 return get_hostkey_by_type(type, 1);
836 get_hostkey_by_index(int ind)
838 if (ind < 0 || ind >= options.num_host_key_files)
840 return (sensitive_data.host_keys[ind]);
844 get_hostkey_index(Key *key)
848 for (i = 0; i < options.num_host_key_files; i++) {
849 if (key_is_cert(key)) {
850 if (key == sensitive_data.host_certificates[i])
853 if (key == sensitive_data.host_keys[i])
861 * returns 1 if connection should be dropped, 0 otherwise.
862 * dropping starts at connection #max_startups_begin with a probability
863 * of (max_startups_rate/100). the probability increases linearly until
864 * all connections are dropped for startups > max_startups
867 drop_connection(int startups)
871 if (startups < options.max_startups_begin)
873 if (startups >= options.max_startups)
875 if (options.max_startups_rate == 100)
878 p = 100 - options.max_startups_rate;
879 p *= startups - options.max_startups_begin;
880 p /= options.max_startups - options.max_startups_begin;
881 p += options.max_startups_rate;
882 r = arc4random_uniform(100);
884 debug("drop_connection: p %d, r %d", p, r);
885 return (r < p) ? 1 : 0;
891 fprintf(stderr, "%s, %s\n",
892 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
894 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
895 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
896 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
902 send_rexec_state(int fd, Buffer *conf)
906 debug3("%s: entering fd = %d config len %d", __func__, fd,
910 * Protocol from reexec master to child:
911 * string configuration
912 * u_int ephemeral_key_follows
913 * bignum e (only if ephemeral_key_follows == 1)
919 * string rngseed (only if OpenSSL is not self-seeded)
922 buffer_put_cstring(&m, buffer_ptr(conf));
924 if (sensitive_data.server_key != NULL &&
925 sensitive_data.server_key->type == KEY_RSA1) {
926 buffer_put_int(&m, 1);
927 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
928 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
929 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
930 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
931 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
932 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
934 buffer_put_int(&m, 0);
936 #ifndef OPENSSL_PRNG_ONLY
937 rexec_send_rng_seed(&m);
940 if (ssh_msg_send(fd, 0, &m) == -1)
941 fatal("%s: ssh_msg_send failed", __func__);
945 debug3("%s: done", __func__);
949 recv_rexec_state(int fd, Buffer *conf)
955 debug3("%s: entering fd = %d", __func__, fd);
959 if (ssh_msg_recv(fd, &m) == -1)
960 fatal("%s: ssh_msg_recv failed", __func__);
961 if (buffer_get_char(&m) != 0)
962 fatal("%s: rexec version mismatch", __func__);
964 cp = buffer_get_string(&m, &len);
966 buffer_append(conf, cp, len + 1);
969 if (buffer_get_int(&m)) {
970 if (sensitive_data.server_key != NULL)
971 key_free(sensitive_data.server_key);
972 sensitive_data.server_key = key_new_private(KEY_RSA1);
973 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
974 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
975 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
976 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
977 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
978 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
979 rsa_generate_additional_parameters(
980 sensitive_data.server_key->rsa);
983 #ifndef OPENSSL_PRNG_ONLY
984 rexec_recv_rng_seed(&m);
989 debug3("%s: done", __func__);
992 /* Accept a connection from inetd */
994 server_accept_inetd(int *sock_in, int *sock_out)
1000 close(REEXEC_CONFIG_PASS_FD);
1001 *sock_in = *sock_out = dup(STDIN_FILENO);
1003 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1004 close(REEXEC_STARTUP_PIPE_FD);
1007 *sock_in = dup(STDIN_FILENO);
1008 *sock_out = dup(STDOUT_FILENO);
1011 * We intentionally do not close the descriptors 0, 1, and 2
1012 * as our code for setting the descriptors won't work if
1013 * ttyfd happens to be one of those.
1015 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1016 dup2(fd, STDIN_FILENO);
1017 dup2(fd, STDOUT_FILENO);
1018 if (fd > STDOUT_FILENO)
1021 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1025 * Listen for TCP connections
1030 int ret, listen_sock, on = 1;
1031 struct addrinfo *ai;
1032 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1034 int socksizelen = sizeof(int);
1036 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1037 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1039 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1040 fatal("Too many listen sockets. "
1041 "Enlarge MAX_LISTEN_SOCKS");
1042 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1043 ntop, sizeof(ntop), strport, sizeof(strport),
1044 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1045 error("getnameinfo failed: %.100s",
1046 ssh_gai_strerror(ret));
1049 /* Create socket for listening. */
1050 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1052 if (listen_sock < 0) {
1053 /* kernel may not support ipv6 */
1054 verbose("socket: %.100s", strerror(errno));
1057 if (set_nonblock(listen_sock) == -1) {
1062 * Set socket options.
1063 * Allow local port reuse in TIME_WAIT.
1065 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1066 &on, sizeof(on)) == -1)
1067 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1069 /* Only communicate in IPv6 over AF_INET6 sockets. */
1070 if (ai->ai_family == AF_INET6)
1071 sock_set_v6only(listen_sock);
1073 debug("Bind to port %s on %s.", strport, ntop);
1075 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF,
1076 &socksize, &socksizelen);
1077 debug("Server TCP RWIN socket size: %d", socksize);
1078 debug("HPN Buffer Size: %d", options.hpn_buffer_size);
1080 /* Bind the socket to the desired port. */
1081 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1082 error("Bind to port %s on %s failed: %.200s.",
1083 strport, ntop, strerror(errno));
1087 listen_socks[num_listen_socks] = listen_sock;
1090 /* Start listening on the port. */
1091 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1092 fatal("listen on [%s]:%s: %.100s",
1093 ntop, strport, strerror(errno));
1094 logit("Server listening on %s port %s.", ntop, strport);
1096 freeaddrinfo(options.listen_addrs);
1098 if (!num_listen_socks)
1099 fatal("Cannot bind any address.");
1103 * The main TCP accept loop. Note that, for the non-debug case, returns
1104 * from this function are in a forked subprocess.
1107 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1110 int i, j, ret, maxfd;
1111 int key_used = 0, startups = 0;
1112 int startup_p[2] = { -1 , -1 };
1113 struct sockaddr_storage from;
1117 /* setup fd set for accept */
1120 for (i = 0; i < num_listen_socks; i++)
1121 if (listen_socks[i] > maxfd)
1122 maxfd = listen_socks[i];
1123 /* pipes connected to unauthenticated childs */
1124 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1125 for (i = 0; i < options.max_startups; i++)
1126 startup_pipes[i] = -1;
1129 * Stay listening for connections until the system crashes or
1130 * the daemon is killed with a signal.
1133 if (received_sighup)
1137 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1140 for (i = 0; i < num_listen_socks; i++)
1141 FD_SET(listen_socks[i], fdset);
1142 for (i = 0; i < options.max_startups; i++)
1143 if (startup_pipes[i] != -1)
1144 FD_SET(startup_pipes[i], fdset);
1146 /* Wait in select until there is a connection. */
1147 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1148 if (ret < 0 && errno != EINTR)
1149 error("select: %.100s", strerror(errno));
1150 if (received_sigterm) {
1151 logit("Received signal %d; terminating.",
1152 (int) received_sigterm);
1153 close_listen_socks();
1154 unlink(options.pid_file);
1155 exit(received_sigterm == SIGTERM ? 0 : 255);
1157 if (key_used && key_do_regen) {
1158 generate_ephemeral_server_key();
1165 for (i = 0; i < options.max_startups; i++)
1166 if (startup_pipes[i] != -1 &&
1167 FD_ISSET(startup_pipes[i], fdset)) {
1169 * the read end of the pipe is ready
1170 * if the child has closed the pipe
1171 * after successful authentication
1172 * or if the child has died
1174 close(startup_pipes[i]);
1175 startup_pipes[i] = -1;
1178 for (i = 0; i < num_listen_socks; i++) {
1179 if (!FD_ISSET(listen_socks[i], fdset))
1181 fromlen = sizeof(from);
1182 *newsock = accept(listen_socks[i],
1183 (struct sockaddr *)&from, &fromlen);
1185 if (errno != EINTR && errno != EAGAIN &&
1186 errno != EWOULDBLOCK)
1187 error("accept: %.100s", strerror(errno));
1190 if (unset_nonblock(*newsock) == -1) {
1194 if (drop_connection(startups) == 1) {
1195 debug("drop connection #%d", startups);
1199 if (pipe(startup_p) == -1) {
1204 if (rexec_flag && socketpair(AF_UNIX,
1205 SOCK_STREAM, 0, config_s) == -1) {
1206 error("reexec socketpair: %s",
1209 close(startup_p[0]);
1210 close(startup_p[1]);
1214 for (j = 0; j < options.max_startups; j++)
1215 if (startup_pipes[j] == -1) {
1216 startup_pipes[j] = startup_p[0];
1217 if (maxfd < startup_p[0])
1218 maxfd = startup_p[0];
1224 * Got connection. Fork a child to handle it, unless
1225 * we are in debugging mode.
1229 * In debugging mode. Close the listening
1230 * socket, and start processing the
1231 * connection without forking.
1233 debug("Server will not fork when running in debugging mode.");
1234 close_listen_socks();
1235 *sock_in = *newsock;
1236 *sock_out = *newsock;
1237 close(startup_p[0]);
1238 close(startup_p[1]);
1242 send_rexec_state(config_s[0],
1250 * Normal production daemon. Fork, and have
1251 * the child process the connection. The
1252 * parent continues listening.
1254 platform_pre_fork();
1255 if ((pid = fork()) == 0) {
1257 * Child. Close the listening and
1258 * max_startup sockets. Start using
1259 * the accepted socket. Reinitialize
1260 * logging (since our pid has changed).
1261 * We break out of the loop to handle
1264 platform_post_fork_child();
1265 startup_pipe = startup_p[1];
1266 close_startup_pipes();
1267 close_listen_socks();
1268 *sock_in = *newsock;
1269 *sock_out = *newsock;
1270 log_init(__progname,
1272 options.log_facility,
1279 /* Parent. Stay in the loop. */
1280 platform_post_fork_parent(pid);
1282 error("fork: %.100s", strerror(errno));
1284 debug("Forked child %ld.", (long)pid);
1286 close(startup_p[1]);
1289 send_rexec_state(config_s[0], &cfg);
1295 * Mark that the key has been used (it
1296 * was "given" to the child).
1298 if ((options.protocol & SSH_PROTO_1) &&
1300 /* Schedule server key regeneration alarm. */
1301 signal(SIGALRM, key_regeneration_alarm);
1302 alarm(options.key_regeneration_time);
1309 * Ensure that our random state differs
1310 * from that of the child
1315 /* child process check (or debug mode) */
1316 if (num_listen_socks < 0)
1323 * Main program for the daemon.
1326 main(int ac, char **av)
1328 extern char *optarg;
1330 int opt, i, j, on = 1;
1331 int sock_in = -1, sock_out = -1, newsock = -1;
1332 const char *remote_ip;
1333 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1335 char *line, *p, *cp;
1336 int config_s[2] = { -1 , -1 };
1337 u_int64_t ibytes, obytes;
1342 #ifdef HAVE_SECUREWARE
1343 (void)set_auth_parameters(ac, av);
1345 __progname = ssh_get_progname(av[0]);
1347 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1350 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1351 for (i = 0; i < ac; i++)
1352 saved_argv[i] = xstrdup(av[i]);
1353 saved_argv[i] = NULL;
1355 #ifndef HAVE_SETPROCTITLE
1356 /* Prepare for later setproctitle emulation */
1357 compat_init_setproctitle(ac, av);
1361 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1362 debug("setgroups(): %.200s", strerror(errno));
1364 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1367 /* Initialize configuration options to their default values. */
1368 initialize_server_options(&options);
1370 /* Parse command-line arguments. */
1371 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1374 options.address_family = AF_INET;
1377 options.address_family = AF_INET6;
1380 config_file_name = optarg;
1383 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1384 fprintf(stderr, "too many host certificates.\n");
1387 options.host_cert_files[options.num_host_cert_files++] =
1388 derelativise_path(optarg);
1391 if (debug_flag == 0) {
1393 options.log_level = SYSLOG_LEVEL_DEBUG1;
1394 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1395 options.log_level++;
1417 options.log_level = SYSLOG_LEVEL_QUIET;
1420 options.server_key_bits = (int)strtonum(optarg, 256,
1424 options.ports_from_cmdline = 1;
1425 if (options.num_ports >= MAX_PORTS) {
1426 fprintf(stderr, "too many ports.\n");
1429 options.ports[options.num_ports++] = a2port(optarg);
1430 if (options.ports[options.num_ports-1] <= 0) {
1431 fprintf(stderr, "Bad port number.\n");
1436 if ((options.login_grace_time = convtime(optarg)) == -1) {
1437 fprintf(stderr, "Invalid login grace time.\n");
1442 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1443 fprintf(stderr, "Invalid key regeneration interval.\n");
1448 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1449 fprintf(stderr, "too many host keys.\n");
1452 options.host_key_files[options.num_host_key_files++] =
1453 derelativise_path(optarg);
1463 while ((p = strsep(&cp, ",")) && *p != '\0') {
1464 if (strncmp(p, "addr=", 5) == 0)
1465 test_addr = xstrdup(p + 5);
1466 else if (strncmp(p, "host=", 5) == 0)
1467 test_host = xstrdup(p + 5);
1468 else if (strncmp(p, "user=", 5) == 0)
1469 test_user = xstrdup(p + 5);
1471 fprintf(stderr, "Invalid test "
1472 "mode specification %s\n", p);
1478 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1479 if (utmp_len > MAXHOSTNAMELEN) {
1480 fprintf(stderr, "Invalid utmp length.\n");
1485 line = xstrdup(optarg);
1486 if (process_server_config_line(&options, line,
1487 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1497 if (rexeced_flag || inetd_flag)
1499 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1500 fatal("sshd re-exec requires execution with an absolute path");
1502 closefrom(REEXEC_MIN_FREE_FD);
1504 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1506 OpenSSL_add_all_algorithms();
1509 * Force logging to stderr until we have loaded the private host
1510 * key (unless started from inetd)
1512 log_init(__progname,
1513 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1514 SYSLOG_LEVEL_INFO : options.log_level,
1515 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1516 SYSLOG_FACILITY_AUTH : options.log_facility,
1517 log_stderr || !inetd_flag);
1520 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1521 * root's environment
1523 if (getenv("KRB5CCNAME") != NULL)
1524 unsetenv("KRB5CCNAME");
1527 /* Cray can define user privs drop all privs now!
1528 * Not needed on PRIV_SU systems!
1533 sensitive_data.server_key = NULL;
1534 sensitive_data.ssh1_host_key = NULL;
1535 sensitive_data.have_ssh1_key = 0;
1536 sensitive_data.have_ssh2_key = 0;
1539 * If we're doing an extended config test, make sure we have all of
1540 * the parameters we need. If we're not doing an extended test,
1541 * do not silently ignore connection test params.
1543 if (test_flag >= 2 &&
1544 (test_user != NULL || test_host != NULL || test_addr != NULL)
1545 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1546 fatal("user, host and addr are all required when testing "
1548 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1550 fatal("Config test connection parameter (-C) provided without "
1553 /* Fetch our configuration */
1556 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1558 load_server_config(config_file_name, &cfg);
1560 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1561 &cfg, NULL, NULL, NULL);
1565 /* Fill in default values for those options not explicitly set. */
1566 fill_default_server_options(&options);
1568 /* challenge-response is implemented via keyboard interactive */
1569 if (options.challenge_response_authentication)
1570 options.kbd_interactive_authentication = 1;
1572 /* set default channel AF */
1573 channel_set_af(options.address_family);
1575 /* Check that there are no remaining arguments. */
1577 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1581 debug("sshd version %.100s", SSH_RELEASE);
1583 /* Store privilege separation user for later use if required. */
1584 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1585 if (use_privsep || options.kerberos_authentication)
1586 fatal("Privilege separation user %s does not exist",
1589 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1590 privsep_pw = pwcopy(privsep_pw);
1591 xfree(privsep_pw->pw_passwd);
1592 privsep_pw->pw_passwd = xstrdup("*");
1596 /* load private host keys */
1597 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1599 for (i = 0; i < options.num_host_key_files; i++)
1600 sensitive_data.host_keys[i] = NULL;
1602 for (i = 0; i < options.num_host_key_files; i++) {
1603 key = key_load_private(options.host_key_files[i], "", NULL);
1604 if (key && blacklisted_key(key)) {
1606 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
1607 if (options.permit_blacklisted_keys)
1608 error("Host key %s blacklisted (see "
1609 "ssh-vulnkey(1)); continuing anyway", fp);
1611 error("Host key %s blacklisted (see "
1612 "ssh-vulnkey(1))", fp);
1614 if (!options.permit_blacklisted_keys) {
1615 sensitive_data.host_keys[i] = NULL;
1619 sensitive_data.host_keys[i] = key;
1621 error("Could not load host key: %s",
1622 options.host_key_files[i]);
1623 sensitive_data.host_keys[i] = NULL;
1626 switch (key->type) {
1628 sensitive_data.ssh1_host_key = key;
1629 sensitive_data.have_ssh1_key = 1;
1634 sensitive_data.have_ssh2_key = 1;
1637 debug("private host key: #%d type %d %s", i, key->type,
1640 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1641 logit("Disabling protocol version 1. Could not load host key");
1642 options.protocol &= ~SSH_PROTO_1;
1644 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1645 logit("Disabling protocol version 2. Could not load host key");
1646 options.protocol &= ~SSH_PROTO_2;
1648 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1649 logit("sshd: no hostkeys available -- exiting.");
1654 * Load certificates. They are stored in an array at identical
1655 * indices to the public keys that they relate to.
1657 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1659 for (i = 0; i < options.num_host_key_files; i++)
1660 sensitive_data.host_certificates[i] = NULL;
1662 for (i = 0; i < options.num_host_cert_files; i++) {
1663 key = key_load_public(options.host_cert_files[i], NULL);
1665 error("Could not load host certificate: %s",
1666 options.host_cert_files[i]);
1669 if (!key_is_cert(key)) {
1670 error("Certificate file is not a certificate: %s",
1671 options.host_cert_files[i]);
1675 /* Find matching private key */
1676 for (j = 0; j < options.num_host_key_files; j++) {
1677 if (key_equal_public(key,
1678 sensitive_data.host_keys[j])) {
1679 sensitive_data.host_certificates[j] = key;
1683 if (j >= options.num_host_key_files) {
1684 error("No matching private key for certificate: %s",
1685 options.host_cert_files[i]);
1689 sensitive_data.host_certificates[j] = key;
1690 debug("host certificate: #%d type %d %s", j, key->type,
1693 /* Check certain values for sanity. */
1694 if (options.protocol & SSH_PROTO_1) {
1695 if (options.server_key_bits < 512 ||
1696 options.server_key_bits > 32768) {
1697 fprintf(stderr, "Bad server key size.\n");
1701 * Check that server and host key lengths differ sufficiently. This
1702 * is necessary to make double encryption work with rsaref. Oh, I
1703 * hate software patents. I dont know if this can go? Niels
1705 if (options.server_key_bits >
1706 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1707 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1708 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1709 SSH_KEY_BITS_RESERVED) {
1710 options.server_key_bits =
1711 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1712 SSH_KEY_BITS_RESERVED;
1713 debug("Forcing server key to %d bits to make it differ from host key.",
1714 options.server_key_bits);
1721 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1722 (S_ISDIR(st.st_mode) == 0))
1723 fatal("Missing privilege separation directory: %s",
1724 _PATH_PRIVSEP_CHROOT_DIR);
1727 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1728 (st.st_uid != getuid () ||
1729 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1731 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1733 fatal("%s must be owned by root and not group or "
1734 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1737 if (test_flag > 1) {
1738 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1739 parse_server_match_config(&options, test_user,
1740 test_host, test_addr);
1741 dump_config(&options);
1744 /* Configuration looks good, so exit if in test mode. */
1749 * Clear out any supplemental groups we may have inherited. This
1750 * prevents inadvertent creation of files with bad modes (in the
1751 * portable version at least, it's certainly possible for PAM
1752 * to create a file, and we can't control the code in every
1753 * module which might be used).
1755 if (setgroups(0, NULL) < 0)
1756 debug("setgroups() failed: %.200s", strerror(errno));
1759 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1760 for (i = 0; i < rexec_argc; i++) {
1761 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1762 rexec_argv[i] = saved_argv[i];
1764 rexec_argv[rexec_argc] = "-R";
1765 rexec_argv[rexec_argc + 1] = NULL;
1768 /* Ensure that umask disallows at least group and world write */
1769 new_umask = umask(0077) | 0022;
1770 (void) umask(new_umask);
1772 /* Initialize the log (it is reinitialized below in case we forked). */
1773 if (debug_flag && (!inetd_flag || rexeced_flag))
1775 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1778 * If not in debugging mode, and not started from inetd, disconnect
1779 * from the controlling terminal, and fork. The original process
1782 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1785 #endif /* TIOCNOTTY */
1786 if (daemon(0, 0) < 0)
1787 fatal("daemon() failed: %.200s", strerror(errno));
1789 /* Disconnect from the controlling tty. */
1791 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1793 (void) ioctl(fd, TIOCNOTTY, NULL);
1796 #endif /* TIOCNOTTY */
1798 /* Reinitialize the log (because of the fork above). */
1799 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1801 /* Initialize the random number generator. */
1804 /* Chdir to the root directory so that the current disk can be
1805 unmounted if desired. */
1808 /* ignore SIGPIPE */
1809 signal(SIGPIPE, SIG_IGN);
1811 /* Get a connection, either from inetd or a listening TCP socket */
1813 server_accept_inetd(&sock_in, &sock_out);
1815 platform_pre_listen();
1818 if (options.protocol & SSH_PROTO_1)
1819 generate_ephemeral_server_key();
1821 signal(SIGHUP, sighup_handler);
1822 signal(SIGCHLD, main_sigchld_handler);
1823 signal(SIGTERM, sigterm_handler);
1824 signal(SIGQUIT, sigterm_handler);
1827 * Write out the pid file after the sigterm handler
1828 * is setup and the listen sockets are bound
1831 FILE *f = fopen(options.pid_file, "w");
1834 error("Couldn't create pid file \"%s\": %s",
1835 options.pid_file, strerror(errno));
1837 fprintf(f, "%ld\n", (long) getpid());
1842 /* Accept a connection and return in a forked child */
1843 server_accept_loop(&sock_in, &sock_out,
1844 &newsock, config_s);
1847 /* This is the child processing a new connection. */
1848 setproctitle("%s", "[accepted]");
1851 * Initialize the resolver. This may not happen automatically
1852 * before privsep chroot().
1854 if ((_res.options & RES_INIT) == 0) {
1855 debug("res_init()");
1860 * Create a new session and process group since the 4.4BSD
1861 * setlogin() affects the entire process group. We don't
1862 * want the child to be able to affect the parent.
1864 #if !defined(SSHD_ACQUIRES_CTTY)
1866 * If setsid is called, on some platforms sshd will later acquire a
1867 * controlling terminal which will result in "could not set
1868 * controlling tty" errors.
1870 if (!debug_flag && !inetd_flag && setsid() < 0)
1871 error("setsid: %.100s", strerror(errno));
1877 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1878 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1879 dup2(newsock, STDIN_FILENO);
1880 dup2(STDIN_FILENO, STDOUT_FILENO);
1881 if (startup_pipe == -1)
1882 close(REEXEC_STARTUP_PIPE_FD);
1884 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1886 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1888 if (startup_pipe != -1)
1889 close(startup_pipe);
1891 execv(rexec_argv[0], rexec_argv);
1893 /* Reexec has failed, fall back and continue */
1894 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1895 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1896 log_init(__progname, options.log_level,
1897 options.log_facility, log_stderr);
1900 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1902 close(REEXEC_CONFIG_PASS_FD);
1903 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1904 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1905 dup2(fd, STDIN_FILENO);
1906 dup2(fd, STDOUT_FILENO);
1907 if (fd > STDERR_FILENO)
1910 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1911 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1914 /* Executed child processes don't need these. */
1915 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1916 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1919 * Disable the key regeneration alarm. We will not regenerate the
1920 * key since we are no longer in a position to give it to anyone. We
1921 * will not restart on SIGHUP since it no longer makes sense.
1924 signal(SIGALRM, SIG_DFL);
1925 signal(SIGHUP, SIG_DFL);
1926 signal(SIGTERM, SIG_DFL);
1927 signal(SIGQUIT, SIG_DFL);
1928 signal(SIGCHLD, SIG_DFL);
1929 signal(SIGINT, SIG_DFL);
1932 * Register our connection. This turns encryption off because we do
1935 packet_set_connection(sock_in, sock_out);
1936 packet_set_server();
1938 /* Set SO_KEEPALIVE if requested. */
1939 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1940 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1941 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1943 if ((remote_port = get_remote_port()) < 0) {
1944 debug("get_remote_port failed");
1949 * We use get_canonical_hostname with usedns = 0 instead of
1950 * get_remote_ipaddr here so IP options will be checked.
1952 (void) get_canonical_hostname(0);
1954 * The rest of the code depends on the fact that
1955 * get_remote_ipaddr() caches the remote ip, even if
1956 * the socket goes away.
1958 remote_ip = get_remote_ipaddr();
1960 #ifdef SSH_AUDIT_EVENTS
1961 audit_connection_from(remote_ip, remote_port);
1964 allow_severity = options.log_facility|LOG_INFO;
1965 deny_severity = options.log_facility|LOG_WARNING;
1966 /* Check whether logins are denied from this host. */
1967 if (packet_connection_is_on_socket()) {
1968 struct request_info req;
1970 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1973 if (!hosts_access(&req)) {
1974 debug("Connection refused by tcp wrapper");
1977 fatal("libwrap refuse returns");
1980 #endif /* LIBWRAP */
1982 /* Log the connection. */
1983 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1985 /* set the HPN options for the child */
1986 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1989 * We don't want to listen forever unless the other side
1990 * successfully authenticates itself. So we set up an alarm which is
1991 * cleared after successful authentication. A limit of zero
1992 * indicates no limit. Note that we don't set the alarm in debugging
1993 * mode; it is just annoying to have the server exit just when you
1994 * are about to discover the bug.
1996 signal(SIGALRM, grace_alarm_handler);
1998 alarm(options.login_grace_time);
2000 sshd_exchange_identification(sock_in, sock_out);
2002 /* In inetd mode, generate ephemeral key only for proto 1 connections */
2003 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
2004 generate_ephemeral_server_key();
2006 packet_set_nonblocking();
2008 /* allocate authentication context */
2009 authctxt = xcalloc(1, sizeof(*authctxt));
2011 authctxt->loginmsg = &loginmsg;
2013 /* XXX global for cleanup, access from other modules */
2014 the_authctxt = authctxt;
2016 /* prepare buffer to collect messages to display to user after login */
2017 buffer_init(&loginmsg);
2021 if (privsep_preauth(authctxt) == 1)
2024 /* perform the key exchange */
2025 /* authenticate user and start session */
2028 do_authentication2(authctxt);
2031 do_authentication(authctxt);
2034 * If we use privilege separation, the unprivileged child transfers
2035 * the current keystate and exits
2038 mm_send_keystate(pmonitor);
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 */
2081 destroy_sensitive_data();
2084 packet_set_timeout(options.client_alive_interval,
2085 options.client_alive_count_max);
2087 /* Start session. */
2088 do_authenticated(authctxt);
2090 /* The connection has been terminated. */
2091 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2092 packet_get_state(MODE_OUT, NULL, NULL, NULL, &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 * Decrypt session_key_int using our private server key and private host key
2117 * (key with larger modulus first).
2120 ssh1_session_key(BIGNUM *session_key_int)
2124 if (BN_cmp(sensitive_data.server_key->rsa->n,
2125 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2126 /* Server key has bigger modulus. */
2127 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2128 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2129 SSH_KEY_BITS_RESERVED) {
2130 fatal("do_connection: %s: "
2131 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2132 get_remote_ipaddr(),
2133 BN_num_bits(sensitive_data.server_key->rsa->n),
2134 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2135 SSH_KEY_BITS_RESERVED);
2137 if (rsa_private_decrypt(session_key_int, session_key_int,
2138 sensitive_data.server_key->rsa) <= 0)
2140 if (rsa_private_decrypt(session_key_int, session_key_int,
2141 sensitive_data.ssh1_host_key->rsa) <= 0)
2144 /* Host key has bigger modulus (or they are equal). */
2145 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2146 BN_num_bits(sensitive_data.server_key->rsa->n) +
2147 SSH_KEY_BITS_RESERVED) {
2148 fatal("do_connection: %s: "
2149 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2150 get_remote_ipaddr(),
2151 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2152 BN_num_bits(sensitive_data.server_key->rsa->n),
2153 SSH_KEY_BITS_RESERVED);
2155 if (rsa_private_decrypt(session_key_int, session_key_int,
2156 sensitive_data.ssh1_host_key->rsa) < 0)
2158 if (rsa_private_decrypt(session_key_int, session_key_int,
2159 sensitive_data.server_key->rsa) < 0)
2172 BIGNUM *session_key_int;
2173 u_char session_key[SSH_SESSION_KEY_LENGTH];
2175 u_int cipher_type, auth_mask, protocol_flags;
2178 * Generate check bytes that the client must send back in the user
2179 * packet in order for it to be accepted; this is used to defy ip
2180 * spoofing attacks. Note that this only works against somebody
2181 * doing IP spoofing from a remote machine; any machine on the local
2182 * network can still see outgoing packets and catch the random
2183 * cookie. This only affects rhosts authentication, and this is one
2184 * of the reasons why it is inherently insecure.
2186 arc4random_buf(cookie, sizeof(cookie));
2189 * Send our public key. We include in the packet 64 bits of random
2190 * data that must be matched in the reply in order to prevent IP
2193 packet_start(SSH_SMSG_PUBLIC_KEY);
2194 for (i = 0; i < 8; i++)
2195 packet_put_char(cookie[i]);
2197 /* Store our public server RSA key. */
2198 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2199 packet_put_bignum(sensitive_data.server_key->rsa->e);
2200 packet_put_bignum(sensitive_data.server_key->rsa->n);
2202 /* Store our public host RSA key. */
2203 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2204 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2205 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2207 /* Put protocol flags. */
2208 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2210 /* Declare which ciphers we support. */
2211 packet_put_int(cipher_mask_ssh1(0));
2213 /* Declare supported authentication types. */
2215 if (options.rhosts_rsa_authentication)
2216 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2217 if (options.rsa_authentication)
2218 auth_mask |= 1 << SSH_AUTH_RSA;
2219 if (options.challenge_response_authentication == 1)
2220 auth_mask |= 1 << SSH_AUTH_TIS;
2221 if (options.password_authentication)
2222 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2223 packet_put_int(auth_mask);
2225 /* Send the packet and wait for it to be sent. */
2227 packet_write_wait();
2229 debug("Sent %d bit server key and %d bit host key.",
2230 BN_num_bits(sensitive_data.server_key->rsa->n),
2231 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2233 /* Read clients reply (cipher type and session key). */
2234 packet_read_expect(SSH_CMSG_SESSION_KEY);
2236 /* Get cipher type and check whether we accept this. */
2237 cipher_type = packet_get_char();
2239 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2240 packet_disconnect("Warning: client selects unsupported cipher.");
2242 /* Get check bytes from the packet. These must match those we
2243 sent earlier with the public key packet. */
2244 for (i = 0; i < 8; i++)
2245 if (cookie[i] != packet_get_char())
2246 packet_disconnect("IP Spoofing check bytes do not match.");
2248 debug("Encryption type: %.200s", cipher_name(cipher_type));
2250 /* Get the encrypted integer. */
2251 if ((session_key_int = BN_new()) == NULL)
2252 fatal("do_ssh1_kex: BN_new failed");
2253 packet_get_bignum(session_key_int);
2255 protocol_flags = packet_get_int();
2256 packet_set_protocol_flags(protocol_flags);
2259 /* Decrypt session_key_int using host/server keys */
2260 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2263 * Extract session key from the decrypted integer. The key is in the
2264 * least significant 256 bits of the integer; the first byte of the
2265 * key is in the highest bits.
2268 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2269 len = BN_num_bytes(session_key_int);
2270 if (len < 0 || (u_int)len > sizeof(session_key)) {
2271 error("do_ssh1_kex: bad session key len from %s: "
2272 "session_key_int %d > sizeof(session_key) %lu",
2273 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2276 memset(session_key, 0, sizeof(session_key));
2277 BN_bn2bin(session_key_int,
2278 session_key + sizeof(session_key) - len);
2280 derive_ssh1_session_id(
2281 sensitive_data.ssh1_host_key->rsa->n,
2282 sensitive_data.server_key->rsa->n,
2283 cookie, session_id);
2285 * Xor the first 16 bytes of the session key with the
2288 for (i = 0; i < 16; i++)
2289 session_key[i] ^= session_id[i];
2293 int bytes = BN_num_bytes(session_key_int);
2294 u_char *buf = xmalloc(bytes);
2297 logit("do_connection: generating a fake encryption key");
2298 BN_bn2bin(session_key_int, buf);
2300 MD5_Update(&md, buf, bytes);
2301 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2302 MD5_Final(session_key, &md);
2304 MD5_Update(&md, session_key, 16);
2305 MD5_Update(&md, buf, bytes);
2306 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2307 MD5_Final(session_key + 16, &md);
2308 memset(buf, 0, bytes);
2310 for (i = 0; i < 16; i++)
2311 session_id[i] = session_key[i] ^ session_key[i + 16];
2313 /* Destroy the private and public keys. No longer. */
2314 destroy_sensitive_data();
2317 mm_ssh1_session_id(session_id);
2319 /* Destroy the decrypted integer. It is no longer needed. */
2320 BN_clear_free(session_key_int);
2322 /* Set the session key. From this on all communications will be encrypted. */
2323 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2325 /* Destroy our copy of the session key. It is no longer needed. */
2326 memset(session_key, 0, sizeof(session_key));
2328 debug("Received session key; encryption turned on.");
2330 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2331 packet_start(SSH_SMSG_SUCCESS);
2333 packet_write_wait();
2337 * SSH2 key exchange: diffie-hellman-group1-sha1
2345 debug ("MYFLAG IS %d", myflag);
2346 if (options.ciphers != NULL) {
2347 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2348 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2349 } else if (options.none_enabled == 1) {
2350 debug ("WARNING: None cipher enabled");
2351 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2352 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE;
2354 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2355 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2356 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2357 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2359 if (options.macs != NULL) {
2360 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2361 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2363 if (options.compression == COMP_NONE) {
2364 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2365 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2366 } else if (options.compression == COMP_DELAYED) {
2367 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2368 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2370 if (options.kex_algorithms != NULL)
2371 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
2373 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2375 /* start key exchange */
2376 kex = kex_setup(myproposal);
2377 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2378 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2379 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2380 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2381 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2383 kex->client_version_string=client_version_string;
2384 kex->server_version_string=server_version_string;
2385 kex->load_host_public_key=&get_hostkey_public_by_type;
2386 kex->load_host_private_key=&get_hostkey_private_by_type;
2387 kex->host_key_index=&get_hostkey_index;
2391 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2393 session_id2 = kex->session_id;
2394 session_id2_len = kex->session_id_len;
2397 /* send 1st encrypted/maced/compressed message */
2398 packet_start(SSH2_MSG_IGNORE);
2399 packet_put_cstring("markus");
2401 packet_write_wait();
2406 /* server specific fatal cleanup */
2411 do_cleanup(the_authctxt);
2412 #ifdef SSH_AUDIT_EVENTS
2413 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2414 if (!use_privsep || mm_is_monitor())
2415 audit_event(SSH_CONNECTION_ABANDON);