1 /* $OpenBSD: sshd.c,v 1.367 2009/05/28 16:50:16 andreas 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>
102 #include "myproposal.h"
103 #include "authfile.h"
104 #include "pathnames.h"
105 #include "atomicio.h"
106 #include "canohost.h"
107 #include "hostfile.h"
111 #include "dispatch.h"
112 #include "channels.h"
114 #include "monitor_mm.h"
119 #include "monitor_wrap.h"
122 #include "ssh-globus-usage.h"
124 #ifdef USE_SECURITY_SESSION_API
125 #include <Security/AuthSession.h>
140 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
141 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
142 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
143 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
148 extern char *__progname;
150 /* Server configuration options. */
151 ServerOptions options;
153 /* Name of the server configuration file. */
154 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
157 * Debug mode flag. This can be set on the command line. If debug
158 * mode is enabled, extra debugging output will be sent to the system
159 * log, the daemon will not go to background, and will exit after processing
160 * the first connection.
164 /* Flag indicating that the daemon should only test the configuration and keys. */
167 /* Flag indicating that the daemon is being started from inetd. */
170 /* Flag indicating that sshd should not detach and become a daemon. */
171 int no_daemon_flag = 0;
173 /* debug goes to stderr unless inetd_flag is set */
176 /* Saved arguments to main(). */
181 int rexeced_flag = 0;
187 * The sockets that the server is listening; this is used in the SIGHUP
190 #define MAX_LISTEN_SOCKS 16
191 int listen_socks[MAX_LISTEN_SOCKS];
192 int num_listen_socks = 0;
195 * the client's version string, passed by sshd2 in compat mode. if != NULL,
196 * sshd will skip the version-number exchange
198 char *client_version_string = NULL;
199 char *server_version_string = NULL;
201 /* for rekeying XXX fixme */
205 * Any really sensitive data in the application is contained in this
206 * structure. The idea is that this structure could be locked into memory so
207 * that the pages do not get written into swap. However, there are some
208 * problems. The private key contains BIGNUMs, and we do not (in principle)
209 * have access to the internals of them, and locking just the structure is
210 * not very useful. Currently, memory locking is not implemented.
213 Key *server_key; /* ephemeral server key */
214 Key *ssh1_host_key; /* ssh1 host key */
215 Key **host_keys; /* all private host keys */
218 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
222 * Flag indicating whether the RSA server key needs to be regenerated.
223 * Is set in the SIGALRM handler and cleared when the key is regenerated.
225 static volatile sig_atomic_t key_do_regen = 0;
227 /* This is set to true when a signal is received. */
228 static volatile sig_atomic_t received_sighup = 0;
229 static volatile sig_atomic_t received_sigterm = 0;
231 /* session identifier, used by RSA-auth */
232 u_char session_id[16];
235 u_char *session_id2 = NULL;
236 u_int session_id2_len = 0;
238 /* record remote hostname or ip */
239 u_int utmp_len = MAXHOSTNAMELEN;
241 /* options.max_startup sized array of fd ints */
242 int *startup_pipes = NULL;
243 int startup_pipe; /* in child */
245 /* variables used for privilege separation */
246 int use_privsep = -1;
247 struct monitor *pmonitor = NULL;
249 /* global authentication context */
250 Authctxt *the_authctxt = NULL;
252 /* sshd_config buffer */
255 /* message to be displayed after login */
258 /* Unprivileged user */
259 struct passwd *privsep_pw = NULL;
261 /* Prototypes for various functions defined later in this file. */
262 void destroy_sensitive_data(void);
263 void demote_sensitive_data(void);
265 static void do_ssh1_kex(void);
266 static void do_ssh2_kex(void);
269 * Close all listening sockets
272 close_listen_socks(void)
276 for (i = 0; i < num_listen_socks; i++)
277 close(listen_socks[i]);
278 num_listen_socks = -1;
282 close_startup_pipes(void)
287 for (i = 0; i < options.max_startups; i++)
288 if (startup_pipes[i] != -1)
289 close(startup_pipes[i]);
293 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
294 * the effect is to reread the configuration file (and to regenerate
300 sighup_handler(int sig)
302 int save_errno = errno;
305 signal(SIGHUP, sighup_handler);
310 * Called from the main program after receiving SIGHUP.
311 * Restarts the server.
316 logit("Received SIGHUP; restarting.");
317 close_listen_socks();
318 close_startup_pipes();
319 alarm(0); /* alarm timer persists across exec */
320 execv(saved_argv[0], saved_argv);
321 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
327 * Generic signal handler for terminating signals in the master daemon.
331 sigterm_handler(int sig)
333 received_sigterm = sig;
337 * SIGCHLD handler. This is called whenever a child dies. This will then
338 * reap any zombies left by exited children.
342 main_sigchld_handler(int sig)
344 int save_errno = errno;
348 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
349 (pid < 0 && errno == EINTR))
352 signal(SIGCHLD, main_sigchld_handler);
357 * Signal handler for the alarm after the login grace period has expired.
361 grace_alarm_handler(int sig)
363 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
364 kill(pmonitor->m_pid, SIGALRM);
366 /* Log error and exit. */
367 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
371 * Signal handler for the key regeneration alarm. Note that this
372 * alarm only occurs in the daemon waiting for connections, and it does not
373 * do anything with the private key or random state before forking.
374 * Thus there should be no concurrency control/asynchronous execution
378 generate_ephemeral_server_key(void)
380 verbose("Generating %s%d bit RSA key.",
381 sensitive_data.server_key ? "new " : "", options.server_key_bits);
382 if (sensitive_data.server_key != NULL)
383 key_free(sensitive_data.server_key);
384 sensitive_data.server_key = key_generate(KEY_RSA1,
385 options.server_key_bits);
386 verbose("RSA key generation complete.");
388 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
394 key_regeneration_alarm(int sig)
396 int save_errno = errno;
398 signal(SIGALRM, SIG_DFL);
404 sshd_exchange_identification(int sock_in, int sock_out)
408 int remote_major, remote_minor;
410 char *s, *newline = "\n";
411 char buf[256]; /* Must not be larger than remote_version. */
412 char remote_version[256]; /* Must be at least as big as buf. */
414 if ((options.protocol & SSH_PROTO_1) &&
415 (options.protocol & SSH_PROTO_2)) {
416 major = PROTOCOL_MAJOR_1;
418 } else if (options.protocol & SSH_PROTO_2) {
419 major = PROTOCOL_MAJOR_2;
420 minor = PROTOCOL_MINOR_2;
423 major = PROTOCOL_MAJOR_1;
424 minor = PROTOCOL_MINOR_1;
426 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
427 SSH_RELEASE, newline);
428 server_version_string = xstrdup(buf);
430 /* Send our protocol version identification. */
431 if (roaming_atomicio(vwrite, sock_out, server_version_string,
432 strlen(server_version_string))
433 != strlen(server_version_string)) {
434 logit("Could not write ident string to %s", get_remote_ipaddr());
438 /* Read other sides version identification. */
439 memset(buf, 0, sizeof(buf));
440 for (i = 0; i < sizeof(buf) - 1; i++) {
441 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
442 logit("Did not receive identification string from %s",
443 get_remote_ipaddr());
446 if (buf[i] == '\r') {
448 /* Kludge for F-Secure Macintosh < 1.0.2 */
450 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
454 if (buf[i] == '\n') {
459 buf[sizeof(buf) - 1] = 0;
460 client_version_string = xstrdup(buf);
463 * Check that the versions match. In future this might accept
464 * several versions and set appropriate flags to handle them.
466 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
467 &remote_major, &remote_minor, remote_version) != 3) {
468 s = "Protocol mismatch.\n";
469 (void) atomicio(vwrite, sock_out, s, strlen(s));
472 logit("Bad protocol version identification '%.100s' from %s",
473 client_version_string, get_remote_ipaddr());
476 debug("Client protocol version %d.%d; client software version %.100s",
477 remote_major, remote_minor, remote_version);
478 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s",
479 get_remote_ipaddr(), get_remote_port(),
480 remote_major, remote_minor, remote_version);
482 compat_datafellows(remote_version);
484 if (datafellows & SSH_BUG_PROBE) {
485 logit("probed from %s with %s. Don't panic.",
486 get_remote_ipaddr(), client_version_string);
490 if (datafellows & SSH_BUG_SCANNER) {
491 logit("scanned from %s with %s. Don't panic.",
492 get_remote_ipaddr(), client_version_string);
497 switch (remote_major) {
499 if (remote_minor == 99) {
500 if (options.protocol & SSH_PROTO_2)
506 if (!(options.protocol & SSH_PROTO_1)) {
510 if (remote_minor < 3) {
511 packet_disconnect("Your ssh version is too old and "
512 "is no longer supported. Please install a newer version.");
513 } else if (remote_minor == 3) {
514 /* note that this disables agent-forwarding */
519 if (options.protocol & SSH_PROTO_2) {
528 chop(server_version_string);
529 debug("Local version string %.200s", server_version_string);
532 s = "Protocol major versions differ.\n";
533 (void) atomicio(vwrite, sock_out, s, strlen(s));
536 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
538 server_version_string, client_version_string);
543 /* Destroy the host and server keys. They will no longer be needed. */
545 destroy_sensitive_data(void)
549 if (sensitive_data.server_key) {
550 key_free(sensitive_data.server_key);
551 sensitive_data.server_key = NULL;
553 for (i = 0; i < options.num_host_key_files; i++) {
554 if (sensitive_data.host_keys[i]) {
555 key_free(sensitive_data.host_keys[i]);
556 sensitive_data.host_keys[i] = NULL;
559 sensitive_data.ssh1_host_key = NULL;
560 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
563 /* Demote private to public keys for network child */
565 demote_sensitive_data(void)
570 if (sensitive_data.server_key) {
571 tmp = key_demote(sensitive_data.server_key);
572 key_free(sensitive_data.server_key);
573 sensitive_data.server_key = tmp;
576 for (i = 0; i < options.num_host_key_files; i++) {
577 if (sensitive_data.host_keys[i]) {
578 tmp = key_demote(sensitive_data.host_keys[i]);
579 key_free(sensitive_data.host_keys[i]);
580 sensitive_data.host_keys[i] = tmp;
581 if (tmp->type == KEY_RSA1)
582 sensitive_data.ssh1_host_key = tmp;
586 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
590 privsep_preauth_child(void)
595 /* Enable challenge-response authentication for privilege separation */
596 privsep_challenge_enable();
599 arc4random_buf(rnd, sizeof(rnd));
600 RAND_seed(rnd, sizeof(rnd));
602 /* Demote the private keys to public keys. */
603 demote_sensitive_data();
605 /* Change our root directory */
606 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
607 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
609 if (chdir("/") == -1)
610 fatal("chdir(\"/\"): %s", strerror(errno));
612 /* Drop our privileges */
613 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
614 (u_int)privsep_pw->pw_gid);
616 /* XXX not ready, too heavy after chroot */
617 do_setusercontext(privsep_pw);
619 gidset[0] = privsep_pw->pw_gid;
620 if (setgroups(1, gidset) < 0)
621 fatal("setgroups: %.100s", strerror(errno));
622 permanently_set_uid(privsep_pw);
627 privsep_preauth(Authctxt *authctxt)
632 /* Set up unprivileged child process to deal with network data */
633 pmonitor = monitor_init();
634 /* Store a pointer to the kex for later rekeying */
635 pmonitor->m_pkex = &xxx_kex;
639 fatal("fork of unprivileged child failed");
640 } else if (pid != 0) {
641 debug2("Network child is on pid %ld", (long)pid);
643 close(pmonitor->m_recvfd);
644 pmonitor->m_pid = pid;
645 monitor_child_preauth(authctxt, pmonitor);
646 close(pmonitor->m_sendfd);
649 monitor_sync(pmonitor);
651 /* Wait for the child's exit status */
652 while (waitpid(pid, &status, 0) < 0)
659 close(pmonitor->m_sendfd);
661 /* Demote the child */
662 if (getuid() == 0 || geteuid() == 0)
663 privsep_preauth_child();
664 setproctitle("%s", "[net]");
670 privsep_postauth(Authctxt *authctxt)
674 #ifdef DISABLE_FD_PASSING
677 if (authctxt->pw->pw_uid == 0 || options.use_login) {
679 /* File descriptor passing is broken or root login */
684 /* New socket pair */
685 monitor_reinit(pmonitor);
687 pmonitor->m_pid = fork();
688 if (pmonitor->m_pid == -1)
689 fatal("fork of unprivileged child failed");
690 else if (pmonitor->m_pid != 0) {
691 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
692 close(pmonitor->m_recvfd);
693 buffer_clear(&loginmsg);
694 monitor_child_postauth(pmonitor);
700 close(pmonitor->m_sendfd);
702 /* Demote the private keys to public keys. */
703 demote_sensitive_data();
706 arc4random_buf(rnd, sizeof(rnd));
707 RAND_seed(rnd, sizeof(rnd));
709 /* Drop privileges */
710 do_setusercontext(authctxt->pw);
713 /* It is safe now to apply the key state */
714 monitor_apply_keystate(pmonitor);
717 * Tell the packet layer that authentication was successful, since
718 * this information is not part of the key state.
720 packet_set_authenticated();
724 list_hostkey_types(void)
732 for (i = 0; i < options.num_host_key_files; i++) {
733 Key *key = sensitive_data.host_keys[i];
739 if (buffer_len(&b) > 0)
740 buffer_append(&b, ",", 1);
741 p = key_ssh_name(key);
742 buffer_append(&b, p, strlen(p));
746 buffer_append(&b, "\0", 1);
747 ret = xstrdup(buffer_ptr(&b));
749 debug("list_hostkey_types: %s", ret);
754 get_hostkey_by_type(int type)
758 for (i = 0; i < options.num_host_key_files; i++) {
759 Key *key = sensitive_data.host_keys[i];
760 if (key != NULL && key->type == type)
767 get_hostkey_by_index(int ind)
769 if (ind < 0 || ind >= options.num_host_key_files)
771 return (sensitive_data.host_keys[ind]);
775 get_hostkey_index(Key *key)
779 for (i = 0; i < options.num_host_key_files; i++) {
780 if (key == sensitive_data.host_keys[i])
787 * returns 1 if connection should be dropped, 0 otherwise.
788 * dropping starts at connection #max_startups_begin with a probability
789 * of (max_startups_rate/100). the probability increases linearly until
790 * all connections are dropped for startups > max_startups
793 drop_connection(int startups)
797 if (startups < options.max_startups_begin)
799 if (startups >= options.max_startups)
801 if (options.max_startups_rate == 100)
804 p = 100 - options.max_startups_rate;
805 p *= startups - options.max_startups_begin;
806 p /= options.max_startups - options.max_startups_begin;
807 p += options.max_startups_rate;
808 r = arc4random_uniform(100);
810 debug("drop_connection: p %d, r %d", p, r);
811 return (r < p) ? 1 : 0;
817 fprintf(stderr, "%s, %s\n",
818 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
820 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n"
821 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n"
822 " [-o option] [-p port] [-u len]\n"
828 send_rexec_state(int fd, Buffer *conf)
832 debug3("%s: entering fd = %d config len %d", __func__, fd,
836 * Protocol from reexec master to child:
837 * string configuration
838 * u_int ephemeral_key_follows
839 * bignum e (only if ephemeral_key_follows == 1)
845 * string rngseed (only if OpenSSL is not self-seeded)
848 buffer_put_cstring(&m, buffer_ptr(conf));
850 if (sensitive_data.server_key != NULL &&
851 sensitive_data.server_key->type == KEY_RSA1) {
852 buffer_put_int(&m, 1);
853 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
854 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
855 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
856 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
857 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
858 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
860 buffer_put_int(&m, 0);
862 #ifndef OPENSSL_PRNG_ONLY
863 rexec_send_rng_seed(&m);
866 if (ssh_msg_send(fd, 0, &m) == -1)
867 fatal("%s: ssh_msg_send failed", __func__);
871 debug3("%s: done", __func__);
875 recv_rexec_state(int fd, Buffer *conf)
881 debug3("%s: entering fd = %d", __func__, fd);
885 if (ssh_msg_recv(fd, &m) == -1)
886 fatal("%s: ssh_msg_recv failed", __func__);
887 if (buffer_get_char(&m) != 0)
888 fatal("%s: rexec version mismatch", __func__);
890 cp = buffer_get_string(&m, &len);
892 buffer_append(conf, cp, len + 1);
895 if (buffer_get_int(&m)) {
896 if (sensitive_data.server_key != NULL)
897 key_free(sensitive_data.server_key);
898 sensitive_data.server_key = key_new_private(KEY_RSA1);
899 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
900 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
901 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
902 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
903 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
904 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
905 rsa_generate_additional_parameters(
906 sensitive_data.server_key->rsa);
909 #ifndef OPENSSL_PRNG_ONLY
910 rexec_recv_rng_seed(&m);
915 debug3("%s: done", __func__);
918 /* Accept a connection from inetd */
920 server_accept_inetd(int *sock_in, int *sock_out)
926 close(REEXEC_CONFIG_PASS_FD);
927 *sock_in = *sock_out = dup(STDIN_FILENO);
929 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
930 close(REEXEC_STARTUP_PIPE_FD);
933 *sock_in = dup(STDIN_FILENO);
934 *sock_out = dup(STDOUT_FILENO);
937 * We intentionally do not close the descriptors 0, 1, and 2
938 * as our code for setting the descriptors won't work if
939 * ttyfd happens to be one of those.
941 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
942 dup2(fd, STDIN_FILENO);
943 dup2(fd, STDOUT_FILENO);
944 if (fd > STDOUT_FILENO)
947 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
951 * Listen for TCP connections
956 int ret, listen_sock, on = 1;
958 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
960 int socksizelen = sizeof(int);
962 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
963 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
965 if (num_listen_socks >= MAX_LISTEN_SOCKS)
966 fatal("Too many listen sockets. "
967 "Enlarge MAX_LISTEN_SOCKS");
968 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
969 ntop, sizeof(ntop), strport, sizeof(strport),
970 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
971 error("getnameinfo failed: %.100s",
972 ssh_gai_strerror(ret));
975 /* Create socket for listening. */
976 listen_sock = socket(ai->ai_family, ai->ai_socktype,
978 if (listen_sock < 0) {
979 /* kernel may not support ipv6 */
980 verbose("socket: %.100s", strerror(errno));
983 if (set_nonblock(listen_sock) == -1) {
988 * Set socket options.
989 * Allow local port reuse in TIME_WAIT.
991 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
992 &on, sizeof(on)) == -1)
993 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
996 /* Only communicate in IPv6 over AF_INET6 sockets. */
997 if (ai->ai_family == AF_INET6) {
998 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY,
999 &on, sizeof(on)) == -1)
1000 error("setsockopt IPV6_V6ONLY: %s",
1005 debug("Bind to port %s on %s.", strport, ntop);
1007 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF,
1008 &socksize, &socksizelen);
1009 debug("Server TCP RWIN socket size: %d", socksize);
1010 debug("HPN Buffer Size: %d", options.hpn_buffer_size);
1012 /* Bind the socket to the desired port. */
1013 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1014 error("Bind to port %s on %s failed: %.200s.",
1015 strport, ntop, strerror(errno));
1019 listen_socks[num_listen_socks] = listen_sock;
1022 /* Start listening on the port. */
1023 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1024 fatal("listen on [%s]:%s: %.100s",
1025 ntop, strport, strerror(errno));
1026 logit("Server listening on %s port %s.", ntop, strport);
1028 freeaddrinfo(options.listen_addrs);
1030 if (!num_listen_socks)
1031 fatal("Cannot bind any address.");
1035 * The main TCP accept loop. Note that, for the non-debug case, returns
1036 * from this function are in a forked subprocess.
1039 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1042 int i, j, ret, maxfd;
1043 int key_used = 0, startups = 0;
1044 int startup_p[2] = { -1 , -1 };
1045 struct sockaddr_storage from;
1049 /* setup fd set for accept */
1052 for (i = 0; i < num_listen_socks; i++)
1053 if (listen_socks[i] > maxfd)
1054 maxfd = listen_socks[i];
1055 /* pipes connected to unauthenticated childs */
1056 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1057 for (i = 0; i < options.max_startups; i++)
1058 startup_pipes[i] = -1;
1061 * Stay listening for connections until the system crashes or
1062 * the daemon is killed with a signal.
1065 if (received_sighup)
1069 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1072 for (i = 0; i < num_listen_socks; i++)
1073 FD_SET(listen_socks[i], fdset);
1074 for (i = 0; i < options.max_startups; i++)
1075 if (startup_pipes[i] != -1)
1076 FD_SET(startup_pipes[i], fdset);
1078 /* Wait in select until there is a connection. */
1079 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1080 if (ret < 0 && errno != EINTR)
1081 error("select: %.100s", strerror(errno));
1082 if (received_sigterm) {
1083 logit("Received signal %d; terminating.",
1084 (int) received_sigterm);
1085 close_listen_socks();
1086 unlink(options.pid_file);
1089 if (key_used && key_do_regen) {
1090 generate_ephemeral_server_key();
1097 for (i = 0; i < options.max_startups; i++)
1098 if (startup_pipes[i] != -1 &&
1099 FD_ISSET(startup_pipes[i], fdset)) {
1101 * the read end of the pipe is ready
1102 * if the child has closed the pipe
1103 * after successful authentication
1104 * or if the child has died
1106 close(startup_pipes[i]);
1107 startup_pipes[i] = -1;
1110 for (i = 0; i < num_listen_socks; i++) {
1111 if (!FD_ISSET(listen_socks[i], fdset))
1113 fromlen = sizeof(from);
1114 *newsock = accept(listen_socks[i],
1115 (struct sockaddr *)&from, &fromlen);
1117 if (errno != EINTR && errno != EAGAIN &&
1118 errno != EWOULDBLOCK)
1119 error("accept: %.100s", strerror(errno));
1122 if (unset_nonblock(*newsock) == -1) {
1126 if (drop_connection(startups) == 1) {
1127 debug("drop connection #%d", startups);
1131 if (pipe(startup_p) == -1) {
1136 if (rexec_flag && socketpair(AF_UNIX,
1137 SOCK_STREAM, 0, config_s) == -1) {
1138 error("reexec socketpair: %s",
1141 close(startup_p[0]);
1142 close(startup_p[1]);
1146 for (j = 0; j < options.max_startups; j++)
1147 if (startup_pipes[j] == -1) {
1148 startup_pipes[j] = startup_p[0];
1149 if (maxfd < startup_p[0])
1150 maxfd = startup_p[0];
1156 * Got connection. Fork a child to handle it, unless
1157 * we are in debugging mode.
1161 * In debugging mode. Close the listening
1162 * socket, and start processing the
1163 * connection without forking.
1165 debug("Server will not fork when running in debugging mode.");
1166 close_listen_socks();
1167 *sock_in = *newsock;
1168 *sock_out = *newsock;
1169 close(startup_p[0]);
1170 close(startup_p[1]);
1174 send_rexec_state(config_s[0],
1182 * Normal production daemon. Fork, and have
1183 * the child process the connection. The
1184 * parent continues listening.
1186 platform_pre_fork();
1187 if ((pid = fork()) == 0) {
1189 * Child. Close the listening and
1190 * max_startup sockets. Start using
1191 * the accepted socket. Reinitialize
1192 * logging (since our pid has changed).
1193 * We break out of the loop to handle
1196 platform_post_fork_child();
1197 startup_pipe = startup_p[1];
1198 close_startup_pipes();
1199 close_listen_socks();
1200 *sock_in = *newsock;
1201 *sock_out = *newsock;
1202 log_init(__progname,
1204 options.log_facility,
1211 /* Parent. Stay in the loop. */
1212 platform_post_fork_parent(pid);
1214 error("fork: %.100s", strerror(errno));
1216 debug("Forked child %ld.", (long)pid);
1218 close(startup_p[1]);
1221 send_rexec_state(config_s[0], &cfg);
1227 * Mark that the key has been used (it
1228 * was "given" to the child).
1230 if ((options.protocol & SSH_PROTO_1) &&
1232 /* Schedule server key regeneration alarm. */
1233 signal(SIGALRM, key_regeneration_alarm);
1234 alarm(options.key_regeneration_time);
1241 * Ensure that our random state differs
1242 * from that of the child
1247 /* child process check (or debug mode) */
1248 if (num_listen_socks < 0)
1255 * Main program for the daemon.
1258 main(int ac, char **av)
1260 extern char *optarg;
1263 int sock_in = -1, sock_out = -1, newsock = -1;
1264 const char *remote_ip;
1265 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1267 char *line, *p, *cp;
1268 int config_s[2] = { -1 , -1 };
1269 u_int64_t ibytes, obytes;
1274 #ifdef HAVE_SECUREWARE
1275 (void)set_auth_parameters(ac, av);
1277 __progname = ssh_get_progname(av[0]);
1280 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1283 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1284 for (i = 0; i < ac; i++)
1285 saved_argv[i] = xstrdup(av[i]);
1286 saved_argv[i] = NULL;
1288 #ifndef HAVE_SETPROCTITLE
1289 /* Prepare for later setproctitle emulation */
1290 compat_init_setproctitle(ac, av);
1294 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1295 debug("setgroups(): %.200s", strerror(errno));
1297 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1300 /* Initialize configuration options to their default values. */
1301 initialize_server_options(&options);
1303 /* Parse command-line arguments. */
1304 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1307 options.address_family = AF_INET;
1310 options.address_family = AF_INET6;
1313 config_file_name = optarg;
1316 if (debug_flag == 0) {
1318 options.log_level = SYSLOG_LEVEL_DEBUG1;
1319 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1320 options.log_level++;
1342 options.log_level = SYSLOG_LEVEL_QUIET;
1345 options.server_key_bits = (int)strtonum(optarg, 256,
1349 options.ports_from_cmdline = 1;
1350 if (options.num_ports >= MAX_PORTS) {
1351 fprintf(stderr, "too many ports.\n");
1354 options.ports[options.num_ports++] = a2port(optarg);
1355 if (options.ports[options.num_ports-1] <= 0) {
1356 fprintf(stderr, "Bad port number.\n");
1361 if ((options.login_grace_time = convtime(optarg)) == -1) {
1362 fprintf(stderr, "Invalid login grace time.\n");
1367 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1368 fprintf(stderr, "Invalid key regeneration interval.\n");
1373 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1374 fprintf(stderr, "too many host keys.\n");
1377 options.host_key_files[options.num_host_key_files++] = optarg;
1387 while ((p = strsep(&cp, ",")) && *p != '\0') {
1388 if (strncmp(p, "addr=", 5) == 0)
1389 test_addr = xstrdup(p + 5);
1390 else if (strncmp(p, "host=", 5) == 0)
1391 test_host = xstrdup(p + 5);
1392 else if (strncmp(p, "user=", 5) == 0)
1393 test_user = xstrdup(p + 5);
1395 fprintf(stderr, "Invalid test "
1396 "mode specification %s\n", p);
1402 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1403 if (utmp_len > MAXHOSTNAMELEN) {
1404 fprintf(stderr, "Invalid utmp length.\n");
1409 line = xstrdup(optarg);
1410 if (process_server_config_line(&options, line,
1411 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1421 if (rexeced_flag || inetd_flag)
1423 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1424 fatal("sshd re-exec requires execution with an absolute path");
1426 closefrom(REEXEC_MIN_FREE_FD);
1428 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1430 SSLeay_add_all_algorithms();
1433 * Force logging to stderr until we have loaded the private host
1434 * key (unless started from inetd)
1436 log_init(__progname,
1437 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1438 SYSLOG_LEVEL_INFO : options.log_level,
1439 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1440 SYSLOG_FACILITY_AUTH : options.log_facility,
1441 log_stderr || !inetd_flag);
1444 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1445 * root's environment
1447 if (getenv("KRB5CCNAME") != NULL)
1448 unsetenv("KRB5CCNAME");
1451 /* Cray can define user privs drop all privs now!
1452 * Not needed on PRIV_SU systems!
1457 sensitive_data.server_key = NULL;
1458 sensitive_data.ssh1_host_key = NULL;
1459 sensitive_data.have_ssh1_key = 0;
1460 sensitive_data.have_ssh2_key = 0;
1463 * If we're doing an extended config test, make sure we have all of
1464 * the parameters we need. If we're not doing an extended test,
1465 * do not silently ignore connection test params.
1467 if (test_flag >= 2 &&
1468 (test_user != NULL || test_host != NULL || test_addr != NULL)
1469 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1470 fatal("user, host and addr are all required when testing "
1472 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1474 fatal("Config test connection parameter (-C) provided without "
1477 /* Fetch our configuration */
1480 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1482 load_server_config(config_file_name, &cfg);
1484 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1485 &cfg, NULL, NULL, NULL);
1489 /* Fill in default values for those options not explicitly set. */
1490 fill_default_server_options(&options);
1492 #ifdef HAVE_GLOBUS_USAGE
1493 if (ssh_usage_stats_init(options.disable_usage_stats,
1494 options.usage_stats_targets) != GLOBUS_SUCCESS) {
1495 fatal("Error initializing Globus Usage Metrics");
1497 #endif /* HAVE_GLOBUS_USAGE */
1499 /* challenge-response is implemented via keyboard interactive */
1500 if (options.challenge_response_authentication)
1501 options.kbd_interactive_authentication = 1;
1503 /* set default channel AF */
1504 channel_set_af(options.address_family);
1506 /* Check that there are no remaining arguments. */
1508 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1512 debug("sshd version %.100s", SSH_RELEASE);
1514 /* Store privilege separation user for later use if required. */
1515 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1516 if (use_privsep || options.kerberos_authentication)
1517 fatal("Privilege separation user %s does not exist",
1520 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1521 privsep_pw = pwcopy(privsep_pw);
1522 xfree(privsep_pw->pw_passwd);
1523 privsep_pw->pw_passwd = xstrdup("*");
1527 /* load private host keys */
1528 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1530 for (i = 0; i < options.num_host_key_files; i++)
1531 sensitive_data.host_keys[i] = NULL;
1533 for (i = 0; i < options.num_host_key_files; i++) {
1534 key = key_load_private(options.host_key_files[i], "", NULL);
1535 sensitive_data.host_keys[i] = key;
1537 error("Could not load host key: %s",
1538 options.host_key_files[i]);
1539 sensitive_data.host_keys[i] = NULL;
1542 switch (key->type) {
1544 sensitive_data.ssh1_host_key = key;
1545 sensitive_data.have_ssh1_key = 1;
1549 sensitive_data.have_ssh2_key = 1;
1552 debug("private host key: #%d type %d %s", i, key->type,
1555 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1556 logit("Disabling protocol version 1. Could not load host key");
1557 options.protocol &= ~SSH_PROTO_1;
1560 /* The GSSAPI key exchange can run without a host key */
1561 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1562 logit("Disabling protocol version 2. Could not load host key");
1563 options.protocol &= ~SSH_PROTO_2;
1566 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1567 logit("sshd: no hostkeys available -- exiting.");
1571 /* Check certain values for sanity. */
1572 if (options.protocol & SSH_PROTO_1) {
1573 if (options.server_key_bits < 512 ||
1574 options.server_key_bits > 32768) {
1575 fprintf(stderr, "Bad server key size.\n");
1579 * Check that server and host key lengths differ sufficiently. This
1580 * is necessary to make double encryption work with rsaref. Oh, I
1581 * hate software patents. I dont know if this can go? Niels
1583 if (options.server_key_bits >
1584 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1585 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1586 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1587 SSH_KEY_BITS_RESERVED) {
1588 options.server_key_bits =
1589 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1590 SSH_KEY_BITS_RESERVED;
1591 debug("Forcing server key to %d bits to make it differ from host key.",
1592 options.server_key_bits);
1599 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1600 (S_ISDIR(st.st_mode) == 0))
1601 fatal("Missing privilege separation directory: %s",
1602 _PATH_PRIVSEP_CHROOT_DIR);
1605 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1606 (st.st_uid != getuid () ||
1607 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1609 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1611 fatal("%s must be owned by root and not group or "
1612 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1615 if (test_flag > 1) {
1616 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1617 parse_server_match_config(&options, test_user,
1618 test_host, test_addr);
1619 dump_config(&options);
1622 /* Configuration looks good, so exit if in test mode. */
1627 * Clear out any supplemental groups we may have inherited. This
1628 * prevents inadvertent creation of files with bad modes (in the
1629 * portable version at least, it's certainly possible for PAM
1630 * to create a file, and we can't control the code in every
1631 * module which might be used).
1633 if (setgroups(0, NULL) < 0)
1634 debug("setgroups() failed: %.200s", strerror(errno));
1637 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1638 for (i = 0; i < rexec_argc; i++) {
1639 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1640 rexec_argv[i] = saved_argv[i];
1642 rexec_argv[rexec_argc] = "-R";
1643 rexec_argv[rexec_argc + 1] = NULL;
1646 /* Ensure that umask disallows at least group and world write */
1647 new_umask = umask(0077) | 0022;
1648 (void) umask(new_umask);
1650 /* Initialize the log (it is reinitialized below in case we forked). */
1651 if (debug_flag && (!inetd_flag || rexeced_flag))
1653 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1656 * If not in debugging mode, and not started from inetd, disconnect
1657 * from the controlling terminal, and fork. The original process
1660 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1663 #endif /* TIOCNOTTY */
1664 if (daemon(0, 0) < 0)
1665 fatal("daemon() failed: %.200s", strerror(errno));
1667 /* Disconnect from the controlling tty. */
1669 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1671 (void) ioctl(fd, TIOCNOTTY, NULL);
1674 #endif /* TIOCNOTTY */
1676 /* Reinitialize the log (because of the fork above). */
1677 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1679 /* Initialize the random number generator. */
1682 /* Chdir to the root directory so that the current disk can be
1683 unmounted if desired. */
1686 /* ignore SIGPIPE */
1687 signal(SIGPIPE, SIG_IGN);
1689 /* Get a connection, either from inetd or a listening TCP socket */
1691 server_accept_inetd(&sock_in, &sock_out);
1695 if (options.protocol & SSH_PROTO_1)
1696 generate_ephemeral_server_key();
1698 signal(SIGHUP, sighup_handler);
1699 signal(SIGCHLD, main_sigchld_handler);
1700 signal(SIGTERM, sigterm_handler);
1701 signal(SIGQUIT, sigterm_handler);
1704 * Write out the pid file after the sigterm handler
1705 * is setup and the listen sockets are bound
1708 FILE *f = fopen(options.pid_file, "w");
1711 error("Couldn't create pid file \"%s\": %s",
1712 options.pid_file, strerror(errno));
1714 fprintf(f, "%ld\n", (long) getpid());
1719 /* Accept a connection and return in a forked child */
1720 server_accept_loop(&sock_in, &sock_out,
1721 &newsock, config_s);
1724 /* This is the child processing a new connection. */
1725 setproctitle("%s", "[accepted]");
1728 * Create a new session and process group since the 4.4BSD
1729 * setlogin() affects the entire process group. We don't
1730 * want the child to be able to affect the parent.
1732 #if !defined(SSHD_ACQUIRES_CTTY)
1734 * If setsid is called, on some platforms sshd will later acquire a
1735 * controlling terminal which will result in "could not set
1736 * controlling tty" errors.
1738 if (!debug_flag && !inetd_flag && setsid() < 0)
1739 error("setsid: %.100s", strerror(errno));
1745 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1746 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1747 dup2(newsock, STDIN_FILENO);
1748 dup2(STDIN_FILENO, STDOUT_FILENO);
1749 if (startup_pipe == -1)
1750 close(REEXEC_STARTUP_PIPE_FD);
1752 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1754 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1756 if (startup_pipe != -1)
1757 close(startup_pipe);
1759 execv(rexec_argv[0], rexec_argv);
1761 /* Reexec has failed, fall back and continue */
1762 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1763 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1764 log_init(__progname, options.log_level,
1765 options.log_facility, log_stderr);
1768 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1770 close(REEXEC_CONFIG_PASS_FD);
1771 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1772 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1773 dup2(fd, STDIN_FILENO);
1774 dup2(fd, STDOUT_FILENO);
1775 if (fd > STDERR_FILENO)
1778 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1779 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1783 * Disable the key regeneration alarm. We will not regenerate the
1784 * key since we are no longer in a position to give it to anyone. We
1785 * will not restart on SIGHUP since it no longer makes sense.
1788 signal(SIGALRM, SIG_DFL);
1789 signal(SIGHUP, SIG_DFL);
1790 signal(SIGTERM, SIG_DFL);
1791 signal(SIGQUIT, SIG_DFL);
1792 signal(SIGCHLD, SIG_DFL);
1793 signal(SIGINT, SIG_DFL);
1796 * Register our connection. This turns encryption off because we do
1799 packet_set_connection(sock_in, sock_out);
1800 packet_set_server();
1802 /* Set SO_KEEPALIVE if requested. */
1803 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1804 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1805 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1807 if ((remote_port = get_remote_port()) < 0) {
1808 debug("get_remote_port failed");
1812 /* set the HPN options for the child */
1813 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1816 * We use get_canonical_hostname with usedns = 0 instead of
1817 * get_remote_ipaddr here so IP options will be checked.
1819 (void) get_canonical_hostname(0);
1821 * The rest of the code depends on the fact that
1822 * get_remote_ipaddr() caches the remote ip, even if
1823 * the socket goes away.
1825 remote_ip = get_remote_ipaddr();
1827 #ifdef SSH_AUDIT_EVENTS
1828 audit_connection_from(remote_ip, remote_port);
1831 allow_severity = options.log_facility|LOG_INFO;
1832 deny_severity = options.log_facility|LOG_WARNING;
1833 /* Check whether logins are denied from this host. */
1834 if (packet_connection_is_on_socket()) {
1835 struct request_info req;
1837 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1840 if (!hosts_access(&req)) {
1841 debug("Connection refused by tcp wrapper");
1844 fatal("libwrap refuse returns");
1847 #endif /* LIBWRAP */
1849 /* Log the connection. */
1850 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1852 #ifdef USE_SECURITY_SESSION_API
1854 * Create a new security session for use by the new user login if
1855 * the current session is the root session or we are not launched
1856 * by inetd (eg: debugging mode or server mode). We do not
1857 * necessarily need to create a session if we are launched from
1858 * inetd because Panther xinetd will create a session for us.
1860 * The only case where this logic will fail is if there is an
1861 * inetd running in a non-root session which is not creating
1862 * new sessions for us. Then all the users will end up in the
1863 * same session (bad).
1865 * When the client exits, the session will be destroyed for us
1868 * We must create the session before any credentials are stored
1869 * (including AFS pags, which happens a few lines below).
1873 SecuritySessionId sid = 0;
1874 SessionAttributeBits sattrs = 0;
1876 err = SessionGetInfo(callerSecuritySession, &sid, &sattrs);
1878 error("SessionGetInfo() failed with error %.8X",
1881 debug("Current Session ID is %.8X / Session Attributes are %.8X",
1882 (unsigned) sid, (unsigned) sattrs);
1884 if (inetd_flag && !(sattrs & sessionIsRoot))
1885 debug("Running in inetd mode in a non-root session... "
1886 "assuming inetd created the session for us.");
1888 debug("Creating new security session...");
1889 err = SessionCreate(0, sessionHasTTY | sessionIsRemote);
1891 error("SessionCreate() failed with error %.8X",
1894 err = SessionGetInfo(callerSecuritySession, &sid,
1897 error("SessionGetInfo() failed with error %.8X",
1900 debug("New Session ID is %.8X / Session Attributes are %.8X",
1901 (unsigned) sid, (unsigned) sattrs);
1907 * We don't want to listen forever unless the other side
1908 * successfully authenticates itself. So we set up an alarm which is
1909 * cleared after successful authentication. A limit of zero
1910 * indicates no limit. Note that we don't set the alarm in debugging
1911 * mode; it is just annoying to have the server exit just when you
1912 * are about to discover the bug.
1914 signal(SIGALRM, grace_alarm_handler);
1916 alarm(options.login_grace_time);
1918 sshd_exchange_identification(sock_in, sock_out);
1919 #if defined(AFS_KRB5)
1920 /* If machine has AFS, set process authentication group. */
1925 #endif /* AFS || AFS_KRB5 */
1927 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1928 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1929 generate_ephemeral_server_key();
1931 packet_set_nonblocking();
1933 /* allocate authentication context */
1934 authctxt = xcalloc(1, sizeof(*authctxt));
1936 authctxt->loginmsg = &loginmsg;
1938 /* XXX global for cleanup, access from other modules */
1939 the_authctxt = authctxt;
1941 /* prepare buffer to collect messages to display to user after login */
1942 buffer_init(&loginmsg);
1945 if (privsep_preauth(authctxt) == 1)
1948 /* perform the key exchange */
1949 /* authenticate user and start session */
1952 do_authentication2(authctxt);
1955 do_authentication(authctxt);
1958 * If we use privilege separation, the unprivileged child transfers
1959 * the current keystate and exits
1962 mm_send_keystate(pmonitor);
1968 * Cancel the alarm we set to limit the time taken for
1972 signal(SIGALRM, SIG_DFL);
1973 authctxt->authenticated = 1;
1974 if (startup_pipe != -1) {
1975 close(startup_pipe);
1979 #ifdef SSH_AUDIT_EVENTS
1980 audit_event(SSH_AUTH_SUCCESS);
1984 if (options.gss_authentication && options.gss_deleg_creds) {
1985 temporarily_use_uid(authctxt->pw);
1986 ssh_gssapi_storecreds();
1991 if (options.use_pam) {
1998 * In privilege separation, we fork another child and prepare
1999 * file descriptor passing.
2002 privsep_postauth(authctxt);
2003 /* the monitor process [priv] will not return */
2005 destroy_sensitive_data();
2008 packet_set_timeout(options.client_alive_interval,
2009 options.client_alive_count_max);
2011 /* Start session. */
2012 do_authenticated(authctxt);
2014 /* The connection has been terminated. */
2015 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2016 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2017 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
2019 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2022 if (options.use_pam)
2024 #endif /* USE_PAM */
2026 #ifdef SSH_AUDIT_EVENTS
2027 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2039 * Decrypt session_key_int using our private server key and private host key
2040 * (key with larger modulus first).
2043 ssh1_session_key(BIGNUM *session_key_int)
2047 if (BN_cmp(sensitive_data.server_key->rsa->n,
2048 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2049 /* Server key has bigger modulus. */
2050 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2051 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2052 SSH_KEY_BITS_RESERVED) {
2053 fatal("do_connection: %s: "
2054 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2055 get_remote_ipaddr(),
2056 BN_num_bits(sensitive_data.server_key->rsa->n),
2057 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2058 SSH_KEY_BITS_RESERVED);
2060 if (rsa_private_decrypt(session_key_int, session_key_int,
2061 sensitive_data.server_key->rsa) <= 0)
2063 if (rsa_private_decrypt(session_key_int, session_key_int,
2064 sensitive_data.ssh1_host_key->rsa) <= 0)
2067 /* Host key has bigger modulus (or they are equal). */
2068 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2069 BN_num_bits(sensitive_data.server_key->rsa->n) +
2070 SSH_KEY_BITS_RESERVED) {
2071 fatal("do_connection: %s: "
2072 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2073 get_remote_ipaddr(),
2074 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2075 BN_num_bits(sensitive_data.server_key->rsa->n),
2076 SSH_KEY_BITS_RESERVED);
2078 if (rsa_private_decrypt(session_key_int, session_key_int,
2079 sensitive_data.ssh1_host_key->rsa) < 0)
2081 if (rsa_private_decrypt(session_key_int, session_key_int,
2082 sensitive_data.server_key->rsa) < 0)
2095 BIGNUM *session_key_int;
2096 u_char session_key[SSH_SESSION_KEY_LENGTH];
2098 u_int cipher_type, auth_mask, protocol_flags;
2101 * Generate check bytes that the client must send back in the user
2102 * packet in order for it to be accepted; this is used to defy ip
2103 * spoofing attacks. Note that this only works against somebody
2104 * doing IP spoofing from a remote machine; any machine on the local
2105 * network can still see outgoing packets and catch the random
2106 * cookie. This only affects rhosts authentication, and this is one
2107 * of the reasons why it is inherently insecure.
2109 arc4random_buf(cookie, sizeof(cookie));
2112 * Send our public key. We include in the packet 64 bits of random
2113 * data that must be matched in the reply in order to prevent IP
2116 packet_start(SSH_SMSG_PUBLIC_KEY);
2117 for (i = 0; i < 8; i++)
2118 packet_put_char(cookie[i]);
2120 /* Store our public server RSA key. */
2121 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2122 packet_put_bignum(sensitive_data.server_key->rsa->e);
2123 packet_put_bignum(sensitive_data.server_key->rsa->n);
2125 /* Store our public host RSA key. */
2126 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2127 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2128 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2130 /* Put protocol flags. */
2131 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2133 /* Declare which ciphers we support. */
2134 packet_put_int(cipher_mask_ssh1(0));
2136 /* Declare supported authentication types. */
2138 if (options.rhosts_rsa_authentication)
2139 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2140 if (options.rsa_authentication)
2141 auth_mask |= 1 << SSH_AUTH_RSA;
2142 if (options.challenge_response_authentication == 1)
2143 auth_mask |= 1 << SSH_AUTH_TIS;
2144 if (options.password_authentication)
2145 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2146 packet_put_int(auth_mask);
2148 /* Send the packet and wait for it to be sent. */
2150 packet_write_wait();
2152 debug("Sent %d bit server key and %d bit host key.",
2153 BN_num_bits(sensitive_data.server_key->rsa->n),
2154 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2156 /* Read clients reply (cipher type and session key). */
2157 packet_read_expect(SSH_CMSG_SESSION_KEY);
2159 /* Get cipher type and check whether we accept this. */
2160 cipher_type = packet_get_char();
2162 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2163 packet_disconnect("Warning: client selects unsupported cipher.");
2165 /* Get check bytes from the packet. These must match those we
2166 sent earlier with the public key packet. */
2167 for (i = 0; i < 8; i++)
2168 if (cookie[i] != packet_get_char())
2169 packet_disconnect("IP Spoofing check bytes do not match.");
2171 debug("Encryption type: %.200s", cipher_name(cipher_type));
2173 /* Get the encrypted integer. */
2174 if ((session_key_int = BN_new()) == NULL)
2175 fatal("do_ssh1_kex: BN_new failed");
2176 packet_get_bignum(session_key_int);
2178 protocol_flags = packet_get_int();
2179 packet_set_protocol_flags(protocol_flags);
2182 /* Decrypt session_key_int using host/server keys */
2183 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2186 * Extract session key from the decrypted integer. The key is in the
2187 * least significant 256 bits of the integer; the first byte of the
2188 * key is in the highest bits.
2191 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2192 len = BN_num_bytes(session_key_int);
2193 if (len < 0 || (u_int)len > sizeof(session_key)) {
2194 error("do_ssh1_kex: bad session key len from %s: "
2195 "session_key_int %d > sizeof(session_key) %lu",
2196 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2199 memset(session_key, 0, sizeof(session_key));
2200 BN_bn2bin(session_key_int,
2201 session_key + sizeof(session_key) - len);
2203 derive_ssh1_session_id(
2204 sensitive_data.ssh1_host_key->rsa->n,
2205 sensitive_data.server_key->rsa->n,
2206 cookie, session_id);
2208 * Xor the first 16 bytes of the session key with the
2211 for (i = 0; i < 16; i++)
2212 session_key[i] ^= session_id[i];
2216 int bytes = BN_num_bytes(session_key_int);
2217 u_char *buf = xmalloc(bytes);
2220 logit("do_connection: generating a fake encryption key");
2221 BN_bn2bin(session_key_int, buf);
2223 MD5_Update(&md, buf, bytes);
2224 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2225 MD5_Final(session_key, &md);
2227 MD5_Update(&md, session_key, 16);
2228 MD5_Update(&md, buf, bytes);
2229 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2230 MD5_Final(session_key + 16, &md);
2231 memset(buf, 0, bytes);
2233 for (i = 0; i < 16; i++)
2234 session_id[i] = session_key[i] ^ session_key[i + 16];
2236 /* Destroy the private and public keys. No longer. */
2237 destroy_sensitive_data();
2240 mm_ssh1_session_id(session_id);
2242 /* Destroy the decrypted integer. It is no longer needed. */
2243 BN_clear_free(session_key_int);
2245 /* Set the session key. From this on all communications will be encrypted. */
2246 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2248 /* Destroy our copy of the session key. It is no longer needed. */
2249 memset(session_key, 0, sizeof(session_key));
2251 debug("Received session key; encryption turned on.");
2253 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2254 packet_start(SSH_SMSG_SUCCESS);
2256 packet_write_wait();
2260 * SSH2 key exchange: diffie-hellman-group1-sha1
2268 debug ("MYFLAG IS %d", myflag);
2269 if (options.ciphers != NULL) {
2270 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2271 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2272 } else if (options.none_enabled == 1) {
2273 debug ("WARNING: None cipher enabled");
2274 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2275 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE;
2277 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2278 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2279 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2280 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2282 if (options.macs != NULL) {
2283 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2284 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2286 if (options.compression == COMP_NONE) {
2287 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2288 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2289 } else if (options.compression == COMP_DELAYED) {
2290 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2291 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2294 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2300 char *newstr = NULL;
2301 orig = myproposal[PROPOSAL_KEX_ALGS];
2304 * If we don't have a host key, then there's no point advertising
2305 * the other key exchange algorithms
2308 if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
2311 if (options.gss_keyex)
2312 gss = ssh_gssapi_server_mechanisms();
2317 xasprintf(&newstr, "%s,%s", gss, orig);
2324 * If we've got GSSAPI mechanisms, then we've got the 'null' host
2325 * key alg, but we can't tell people about it unless its the only
2326 * host key algorithm we support
2328 if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
2329 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
2332 myproposal[PROPOSAL_KEX_ALGS] = newstr;
2334 fatal("No supported key exchange algorithms");
2338 /* start key exchange */
2339 kex = kex_setup(myproposal);
2340 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2341 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2342 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2343 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2345 if (options.gss_keyex) {
2346 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
2347 kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
2348 kex->kex[KEX_GSS_GEX_SHA1] = kexgss_server;
2352 kex->client_version_string=client_version_string;
2353 kex->server_version_string=server_version_string;
2354 kex->load_host_key=&get_hostkey_by_type;
2355 kex->host_key_index=&get_hostkey_index;
2359 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2361 session_id2 = kex->session_id;
2362 session_id2_len = kex->session_id_len;
2365 /* send 1st encrypted/maced/compressed message */
2366 packet_start(SSH2_MSG_IGNORE);
2367 packet_put_cstring("markus");
2369 packet_write_wait();
2374 /* server specific fatal cleanup */
2379 do_cleanup(the_authctxt);
2380 #ifdef SSH_AUDIT_EVENTS
2381 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2382 if (!use_privsep || mm_is_monitor())
2383 audit_event(SSH_CONNECTION_ABANDON);