1 /* $OpenBSD: sshd.c,v 1.372 2010/01/29 00:20:41 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>
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"
135 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
136 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
137 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
138 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
140 extern char *__progname;
142 /* Server configuration options. */
143 ServerOptions options;
145 /* Name of the server configuration file. */
146 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
149 * Debug mode flag. This can be set on the command line. If debug
150 * mode is enabled, extra debugging output will be sent to the system
151 * log, the daemon will not go to background, and will exit after processing
152 * the first connection.
156 /* Flag indicating that the daemon should only test the configuration and keys. */
159 /* Flag indicating that the daemon is being started from inetd. */
162 /* Flag indicating that sshd should not detach and become a daemon. */
163 int no_daemon_flag = 0;
165 /* debug goes to stderr unless inetd_flag is set */
168 /* Saved arguments to main(). */
173 int rexeced_flag = 0;
179 * The sockets that the server is listening; this is used in the SIGHUP
182 #define MAX_LISTEN_SOCKS 16
183 int listen_socks[MAX_LISTEN_SOCKS];
184 int num_listen_socks = 0;
187 * the client's version string, passed by sshd2 in compat mode. if != NULL,
188 * sshd will skip the version-number exchange
190 char *client_version_string = NULL;
191 char *server_version_string = NULL;
193 /* for rekeying XXX fixme */
197 * Any really sensitive data in the application is contained in this
198 * structure. The idea is that this structure could be locked into memory so
199 * that the pages do not get written into swap. However, there are some
200 * problems. The private key contains BIGNUMs, and we do not (in principle)
201 * have access to the internals of them, and locking just the structure is
202 * not very useful. Currently, memory locking is not implemented.
205 Key *server_key; /* ephemeral server key */
206 Key *ssh1_host_key; /* ssh1 host key */
207 Key **host_keys; /* all private host keys */
210 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
214 * Flag indicating whether the RSA server key needs to be regenerated.
215 * Is set in the SIGALRM handler and cleared when the key is regenerated.
217 static volatile sig_atomic_t key_do_regen = 0;
219 /* This is set to true when a signal is received. */
220 static volatile sig_atomic_t received_sighup = 0;
221 static volatile sig_atomic_t received_sigterm = 0;
223 /* session identifier, used by RSA-auth */
224 u_char session_id[16];
227 u_char *session_id2 = NULL;
228 u_int session_id2_len = 0;
230 /* record remote hostname or ip */
231 u_int utmp_len = MAXHOSTNAMELEN;
233 /* options.max_startup sized array of fd ints */
234 int *startup_pipes = NULL;
235 int startup_pipe; /* in child */
237 /* variables used for privilege separation */
238 int use_privsep = -1;
239 struct monitor *pmonitor = NULL;
241 /* global authentication context */
242 Authctxt *the_authctxt = NULL;
244 /* sshd_config buffer */
247 /* message to be displayed after login */
250 /* Unprivileged user */
251 struct passwd *privsep_pw = NULL;
253 /* Prototypes for various functions defined later in this file. */
254 void destroy_sensitive_data(void);
255 void demote_sensitive_data(void);
257 static void do_ssh1_kex(void);
258 static void do_ssh2_kex(void);
261 * Close all listening sockets
264 close_listen_socks(void)
268 for (i = 0; i < num_listen_socks; i++)
269 close(listen_socks[i]);
270 num_listen_socks = -1;
274 close_startup_pipes(void)
279 for (i = 0; i < options.max_startups; i++)
280 if (startup_pipes[i] != -1)
281 close(startup_pipes[i]);
285 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
286 * the effect is to reread the configuration file (and to regenerate
292 sighup_handler(int sig)
294 int save_errno = errno;
297 signal(SIGHUP, sighup_handler);
302 * Called from the main program after receiving SIGHUP.
303 * Restarts the server.
308 logit("Received SIGHUP; restarting.");
309 close_listen_socks();
310 close_startup_pipes();
311 alarm(0); /* alarm timer persists across exec */
312 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
313 execv(saved_argv[0], saved_argv);
314 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
320 * Generic signal handler for terminating signals in the master daemon.
324 sigterm_handler(int sig)
326 received_sigterm = sig;
330 * SIGCHLD handler. This is called whenever a child dies. This will then
331 * reap any zombies left by exited children.
335 main_sigchld_handler(int sig)
337 int save_errno = errno;
341 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
342 (pid < 0 && errno == EINTR))
345 signal(SIGCHLD, main_sigchld_handler);
350 * Signal handler for the alarm after the login grace period has expired.
354 grace_alarm_handler(int sig)
356 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
357 kill(pmonitor->m_pid, SIGALRM);
359 /* Log error and exit. */
360 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
364 * Signal handler for the key regeneration alarm. Note that this
365 * alarm only occurs in the daemon waiting for connections, and it does not
366 * do anything with the private key or random state before forking.
367 * Thus there should be no concurrency control/asynchronous execution
371 generate_ephemeral_server_key(void)
373 verbose("Generating %s%d bit RSA key.",
374 sensitive_data.server_key ? "new " : "", options.server_key_bits);
375 if (sensitive_data.server_key != NULL)
376 key_free(sensitive_data.server_key);
377 sensitive_data.server_key = key_generate(KEY_RSA1,
378 options.server_key_bits);
379 verbose("RSA key generation complete.");
381 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
387 key_regeneration_alarm(int sig)
389 int save_errno = errno;
391 signal(SIGALRM, SIG_DFL);
397 sshd_exchange_identification(int sock_in, int sock_out)
401 int remote_major, remote_minor;
403 char *s, *newline = "\n";
404 char buf[256]; /* Must not be larger than remote_version. */
405 char remote_version[256]; /* Must be at least as big as buf. */
407 if ((options.protocol & SSH_PROTO_1) &&
408 (options.protocol & SSH_PROTO_2)) {
409 major = PROTOCOL_MAJOR_1;
411 } else if (options.protocol & SSH_PROTO_2) {
412 major = PROTOCOL_MAJOR_2;
413 minor = PROTOCOL_MINOR_2;
416 major = PROTOCOL_MAJOR_1;
417 minor = PROTOCOL_MINOR_1;
419 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
420 SSH_VERSION, newline);
421 server_version_string = xstrdup(buf);
423 /* Send our protocol version identification. */
424 if (roaming_atomicio(vwrite, sock_out, server_version_string,
425 strlen(server_version_string))
426 != strlen(server_version_string)) {
427 logit("Could not write ident string to %s", get_remote_ipaddr());
431 /* Read other sides version identification. */
432 memset(buf, 0, sizeof(buf));
433 for (i = 0; i < sizeof(buf) - 1; i++) {
434 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
435 logit("Did not receive identification string from %s",
436 get_remote_ipaddr());
439 if (buf[i] == '\r') {
441 /* Kludge for F-Secure Macintosh < 1.0.2 */
443 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
447 if (buf[i] == '\n') {
452 buf[sizeof(buf) - 1] = 0;
453 client_version_string = xstrdup(buf);
456 * Check that the versions match. In future this might accept
457 * several versions and set appropriate flags to handle them.
459 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
460 &remote_major, &remote_minor, remote_version) != 3) {
461 s = "Protocol mismatch.\n";
462 (void) atomicio(vwrite, sock_out, s, strlen(s));
465 logit("Bad protocol version identification '%.100s' from %s",
466 client_version_string, get_remote_ipaddr());
469 debug("Client protocol version %d.%d; client software version %.100s",
470 remote_major, remote_minor, remote_version);
472 compat_datafellows(remote_version);
474 if (datafellows & SSH_BUG_PROBE) {
475 logit("probed from %s with %s. Don't panic.",
476 get_remote_ipaddr(), client_version_string);
480 if (datafellows & SSH_BUG_SCANNER) {
481 logit("scanned from %s with %s. Don't panic.",
482 get_remote_ipaddr(), client_version_string);
487 switch (remote_major) {
489 if (remote_minor == 99) {
490 if (options.protocol & SSH_PROTO_2)
496 if (!(options.protocol & SSH_PROTO_1)) {
500 if (remote_minor < 3) {
501 packet_disconnect("Your ssh version is too old and "
502 "is no longer supported. Please install a newer version.");
503 } else if (remote_minor == 3) {
504 /* note that this disables agent-forwarding */
509 if (options.protocol & SSH_PROTO_2) {
518 chop(server_version_string);
519 debug("Local version string %.200s", server_version_string);
522 s = "Protocol major versions differ.\n";
523 (void) atomicio(vwrite, sock_out, s, strlen(s));
526 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
528 server_version_string, client_version_string);
533 /* Destroy the host and server keys. They will no longer be needed. */
535 destroy_sensitive_data(void)
539 if (sensitive_data.server_key) {
540 key_free(sensitive_data.server_key);
541 sensitive_data.server_key = NULL;
543 for (i = 0; i < options.num_host_key_files; i++) {
544 if (sensitive_data.host_keys[i]) {
545 key_free(sensitive_data.host_keys[i]);
546 sensitive_data.host_keys[i] = NULL;
549 sensitive_data.ssh1_host_key = NULL;
550 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
553 /* Demote private to public keys for network child */
555 demote_sensitive_data(void)
560 if (sensitive_data.server_key) {
561 tmp = key_demote(sensitive_data.server_key);
562 key_free(sensitive_data.server_key);
563 sensitive_data.server_key = tmp;
566 for (i = 0; i < options.num_host_key_files; i++) {
567 if (sensitive_data.host_keys[i]) {
568 tmp = key_demote(sensitive_data.host_keys[i]);
569 key_free(sensitive_data.host_keys[i]);
570 sensitive_data.host_keys[i] = tmp;
571 if (tmp->type == KEY_RSA1)
572 sensitive_data.ssh1_host_key = tmp;
576 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
580 privsep_preauth_child(void)
585 /* Enable challenge-response authentication for privilege separation */
586 privsep_challenge_enable();
589 arc4random_buf(rnd, sizeof(rnd));
590 RAND_seed(rnd, sizeof(rnd));
592 /* Demote the private keys to public keys. */
593 demote_sensitive_data();
595 /* Change our root directory */
596 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
597 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
599 if (chdir("/") == -1)
600 fatal("chdir(\"/\"): %s", strerror(errno));
602 /* Drop our privileges */
603 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
604 (u_int)privsep_pw->pw_gid);
606 /* XXX not ready, too heavy after chroot */
607 do_setusercontext(privsep_pw);
609 gidset[0] = privsep_pw->pw_gid;
610 if (setgroups(1, gidset) < 0)
611 fatal("setgroups: %.100s", strerror(errno));
612 permanently_set_uid(privsep_pw);
617 privsep_preauth(Authctxt *authctxt)
622 /* Set up unprivileged child process to deal with network data */
623 pmonitor = monitor_init();
624 /* Store a pointer to the kex for later rekeying */
625 pmonitor->m_pkex = &xxx_kex;
629 fatal("fork of unprivileged child failed");
630 } else if (pid != 0) {
631 debug2("Network child is on pid %ld", (long)pid);
633 close(pmonitor->m_recvfd);
634 pmonitor->m_pid = pid;
635 monitor_child_preauth(authctxt, pmonitor);
636 close(pmonitor->m_sendfd);
639 monitor_sync(pmonitor);
641 /* Wait for the child's exit status */
642 while (waitpid(pid, &status, 0) < 0)
649 close(pmonitor->m_sendfd);
651 /* Demote the child */
652 if (getuid() == 0 || geteuid() == 0)
653 privsep_preauth_child();
654 setproctitle("%s", "[net]");
660 privsep_postauth(Authctxt *authctxt)
664 #ifdef DISABLE_FD_PASSING
667 if (authctxt->pw->pw_uid == 0 || options.use_login) {
669 /* File descriptor passing is broken or root login */
674 /* New socket pair */
675 monitor_reinit(pmonitor);
677 pmonitor->m_pid = fork();
678 if (pmonitor->m_pid == -1)
679 fatal("fork of unprivileged child failed");
680 else if (pmonitor->m_pid != 0) {
681 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
682 close(pmonitor->m_recvfd);
683 buffer_clear(&loginmsg);
684 monitor_child_postauth(pmonitor);
690 close(pmonitor->m_sendfd);
692 /* Demote the private keys to public keys. */
693 demote_sensitive_data();
696 arc4random_buf(rnd, sizeof(rnd));
697 RAND_seed(rnd, sizeof(rnd));
699 /* Drop privileges */
700 do_setusercontext(authctxt->pw);
703 /* It is safe now to apply the key state */
704 monitor_apply_keystate(pmonitor);
707 * Tell the packet layer that authentication was successful, since
708 * this information is not part of the key state.
710 packet_set_authenticated();
714 list_hostkey_types(void)
722 for (i = 0; i < options.num_host_key_files; i++) {
723 Key *key = sensitive_data.host_keys[i];
729 if (buffer_len(&b) > 0)
730 buffer_append(&b, ",", 1);
731 p = key_ssh_name(key);
732 buffer_append(&b, p, strlen(p));
736 buffer_append(&b, "\0", 1);
737 ret = xstrdup(buffer_ptr(&b));
739 debug("list_hostkey_types: %s", ret);
744 get_hostkey_by_type(int type)
748 for (i = 0; i < options.num_host_key_files; i++) {
749 Key *key = sensitive_data.host_keys[i];
750 if (key != NULL && key->type == type)
757 get_hostkey_by_index(int ind)
759 if (ind < 0 || ind >= options.num_host_key_files)
761 return (sensitive_data.host_keys[ind]);
765 get_hostkey_index(Key *key)
769 for (i = 0; i < options.num_host_key_files; i++) {
770 if (key == sensitive_data.host_keys[i])
777 * returns 1 if connection should be dropped, 0 otherwise.
778 * dropping starts at connection #max_startups_begin with a probability
779 * of (max_startups_rate/100). the probability increases linearly until
780 * all connections are dropped for startups > max_startups
783 drop_connection(int startups)
787 if (startups < options.max_startups_begin)
789 if (startups >= options.max_startups)
791 if (options.max_startups_rate == 100)
794 p = 100 - options.max_startups_rate;
795 p *= startups - options.max_startups_begin;
796 p /= options.max_startups - options.max_startups_begin;
797 p += options.max_startups_rate;
798 r = arc4random_uniform(100);
800 debug("drop_connection: p %d, r %d", p, r);
801 return (r < p) ? 1 : 0;
807 fprintf(stderr, "%s, %s\n",
808 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
810 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n"
811 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n"
812 " [-o option] [-p port] [-u len]\n"
818 send_rexec_state(int fd, Buffer *conf)
822 debug3("%s: entering fd = %d config len %d", __func__, fd,
826 * Protocol from reexec master to child:
827 * string configuration
828 * u_int ephemeral_key_follows
829 * bignum e (only if ephemeral_key_follows == 1)
835 * string rngseed (only if OpenSSL is not self-seeded)
838 buffer_put_cstring(&m, buffer_ptr(conf));
840 if (sensitive_data.server_key != NULL &&
841 sensitive_data.server_key->type == KEY_RSA1) {
842 buffer_put_int(&m, 1);
843 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
844 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
845 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
846 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
847 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
848 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
850 buffer_put_int(&m, 0);
852 #ifndef OPENSSL_PRNG_ONLY
853 rexec_send_rng_seed(&m);
856 if (ssh_msg_send(fd, 0, &m) == -1)
857 fatal("%s: ssh_msg_send failed", __func__);
861 debug3("%s: done", __func__);
865 recv_rexec_state(int fd, Buffer *conf)
871 debug3("%s: entering fd = %d", __func__, fd);
875 if (ssh_msg_recv(fd, &m) == -1)
876 fatal("%s: ssh_msg_recv failed", __func__);
877 if (buffer_get_char(&m) != 0)
878 fatal("%s: rexec version mismatch", __func__);
880 cp = buffer_get_string(&m, &len);
882 buffer_append(conf, cp, len + 1);
885 if (buffer_get_int(&m)) {
886 if (sensitive_data.server_key != NULL)
887 key_free(sensitive_data.server_key);
888 sensitive_data.server_key = key_new_private(KEY_RSA1);
889 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
890 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
891 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
892 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
893 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
894 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
895 rsa_generate_additional_parameters(
896 sensitive_data.server_key->rsa);
899 #ifndef OPENSSL_PRNG_ONLY
900 rexec_recv_rng_seed(&m);
905 debug3("%s: done", __func__);
908 /* Accept a connection from inetd */
910 server_accept_inetd(int *sock_in, int *sock_out)
916 close(REEXEC_CONFIG_PASS_FD);
917 *sock_in = *sock_out = dup(STDIN_FILENO);
919 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
920 close(REEXEC_STARTUP_PIPE_FD);
923 *sock_in = dup(STDIN_FILENO);
924 *sock_out = dup(STDOUT_FILENO);
927 * We intentionally do not close the descriptors 0, 1, and 2
928 * as our code for setting the descriptors won't work if
929 * ttyfd happens to be one of those.
931 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
932 dup2(fd, STDIN_FILENO);
933 dup2(fd, STDOUT_FILENO);
934 if (fd > STDOUT_FILENO)
937 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
941 * Listen for TCP connections
946 int ret, listen_sock, on = 1;
948 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
950 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
951 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
953 if (num_listen_socks >= MAX_LISTEN_SOCKS)
954 fatal("Too many listen sockets. "
955 "Enlarge MAX_LISTEN_SOCKS");
956 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
957 ntop, sizeof(ntop), strport, sizeof(strport),
958 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
959 error("getnameinfo failed: %.100s",
960 ssh_gai_strerror(ret));
963 /* Create socket for listening. */
964 listen_sock = socket(ai->ai_family, ai->ai_socktype,
966 if (listen_sock < 0) {
967 /* kernel may not support ipv6 */
968 verbose("socket: %.100s", strerror(errno));
971 if (set_nonblock(listen_sock) == -1) {
976 * Set socket options.
977 * Allow local port reuse in TIME_WAIT.
979 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
980 &on, sizeof(on)) == -1)
981 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
983 /* Only communicate in IPv6 over AF_INET6 sockets. */
984 if (ai->ai_family == AF_INET6)
985 sock_set_v6only(listen_sock);
987 debug("Bind to port %s on %s.", strport, ntop);
989 /* Bind the socket to the desired port. */
990 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
991 error("Bind to port %s on %s failed: %.200s.",
992 strport, ntop, strerror(errno));
996 listen_socks[num_listen_socks] = listen_sock;
999 /* Start listening on the port. */
1000 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1001 fatal("listen on [%s]:%s: %.100s",
1002 ntop, strport, strerror(errno));
1003 logit("Server listening on %s port %s.", ntop, strport);
1005 freeaddrinfo(options.listen_addrs);
1007 if (!num_listen_socks)
1008 fatal("Cannot bind any address.");
1012 * The main TCP accept loop. Note that, for the non-debug case, returns
1013 * from this function are in a forked subprocess.
1016 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1019 int i, j, ret, maxfd;
1020 int key_used = 0, startups = 0;
1021 int startup_p[2] = { -1 , -1 };
1022 struct sockaddr_storage from;
1026 /* setup fd set for accept */
1029 for (i = 0; i < num_listen_socks; i++)
1030 if (listen_socks[i] > maxfd)
1031 maxfd = listen_socks[i];
1032 /* pipes connected to unauthenticated childs */
1033 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1034 for (i = 0; i < options.max_startups; i++)
1035 startup_pipes[i] = -1;
1038 * Stay listening for connections until the system crashes or
1039 * the daemon is killed with a signal.
1042 if (received_sighup)
1046 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1049 for (i = 0; i < num_listen_socks; i++)
1050 FD_SET(listen_socks[i], fdset);
1051 for (i = 0; i < options.max_startups; i++)
1052 if (startup_pipes[i] != -1)
1053 FD_SET(startup_pipes[i], fdset);
1055 /* Wait in select until there is a connection. */
1056 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1057 if (ret < 0 && errno != EINTR)
1058 error("select: %.100s", strerror(errno));
1059 if (received_sigterm) {
1060 logit("Received signal %d; terminating.",
1061 (int) received_sigterm);
1062 close_listen_socks();
1063 unlink(options.pid_file);
1066 if (key_used && key_do_regen) {
1067 generate_ephemeral_server_key();
1074 for (i = 0; i < options.max_startups; i++)
1075 if (startup_pipes[i] != -1 &&
1076 FD_ISSET(startup_pipes[i], fdset)) {
1078 * the read end of the pipe is ready
1079 * if the child has closed the pipe
1080 * after successful authentication
1081 * or if the child has died
1083 close(startup_pipes[i]);
1084 startup_pipes[i] = -1;
1087 for (i = 0; i < num_listen_socks; i++) {
1088 if (!FD_ISSET(listen_socks[i], fdset))
1090 fromlen = sizeof(from);
1091 *newsock = accept(listen_socks[i],
1092 (struct sockaddr *)&from, &fromlen);
1094 if (errno != EINTR && errno != EAGAIN &&
1095 errno != EWOULDBLOCK)
1096 error("accept: %.100s", strerror(errno));
1099 if (unset_nonblock(*newsock) == -1) {
1103 if (drop_connection(startups) == 1) {
1104 debug("drop connection #%d", startups);
1108 if (pipe(startup_p) == -1) {
1113 if (rexec_flag && socketpair(AF_UNIX,
1114 SOCK_STREAM, 0, config_s) == -1) {
1115 error("reexec socketpair: %s",
1118 close(startup_p[0]);
1119 close(startup_p[1]);
1123 for (j = 0; j < options.max_startups; j++)
1124 if (startup_pipes[j] == -1) {
1125 startup_pipes[j] = startup_p[0];
1126 if (maxfd < startup_p[0])
1127 maxfd = startup_p[0];
1133 * Got connection. Fork a child to handle it, unless
1134 * we are in debugging mode.
1138 * In debugging mode. Close the listening
1139 * socket, and start processing the
1140 * connection without forking.
1142 debug("Server will not fork when running in debugging mode.");
1143 close_listen_socks();
1144 *sock_in = *newsock;
1145 *sock_out = *newsock;
1146 close(startup_p[0]);
1147 close(startup_p[1]);
1151 send_rexec_state(config_s[0],
1159 * Normal production daemon. Fork, and have
1160 * the child process the connection. The
1161 * parent continues listening.
1163 platform_pre_fork();
1164 if ((pid = fork()) == 0) {
1166 * Child. Close the listening and
1167 * max_startup sockets. Start using
1168 * the accepted socket. Reinitialize
1169 * logging (since our pid has changed).
1170 * We break out of the loop to handle
1173 platform_post_fork_child();
1174 startup_pipe = startup_p[1];
1175 close_startup_pipes();
1176 close_listen_socks();
1177 *sock_in = *newsock;
1178 *sock_out = *newsock;
1179 log_init(__progname,
1181 options.log_facility,
1188 /* Parent. Stay in the loop. */
1189 platform_post_fork_parent(pid);
1191 error("fork: %.100s", strerror(errno));
1193 debug("Forked child %ld.", (long)pid);
1195 close(startup_p[1]);
1198 send_rexec_state(config_s[0], &cfg);
1204 * Mark that the key has been used (it
1205 * was "given" to the child).
1207 if ((options.protocol & SSH_PROTO_1) &&
1209 /* Schedule server key regeneration alarm. */
1210 signal(SIGALRM, key_regeneration_alarm);
1211 alarm(options.key_regeneration_time);
1218 * Ensure that our random state differs
1219 * from that of the child
1224 /* child process check (or debug mode) */
1225 if (num_listen_socks < 0)
1232 * Main program for the daemon.
1235 main(int ac, char **av)
1237 extern char *optarg;
1240 int sock_in = -1, sock_out = -1, newsock = -1;
1241 const char *remote_ip;
1242 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1244 char *line, *p, *cp;
1245 int config_s[2] = { -1 , -1 };
1246 u_int64_t ibytes, obytes;
1251 #ifdef HAVE_SECUREWARE
1252 (void)set_auth_parameters(ac, av);
1254 __progname = ssh_get_progname(av[0]);
1257 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1260 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1261 for (i = 0; i < ac; i++)
1262 saved_argv[i] = xstrdup(av[i]);
1263 saved_argv[i] = NULL;
1265 #ifndef HAVE_SETPROCTITLE
1266 /* Prepare for later setproctitle emulation */
1267 compat_init_setproctitle(ac, av);
1271 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1272 debug("setgroups(): %.200s", strerror(errno));
1274 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1277 /* Initialize configuration options to their default values. */
1278 initialize_server_options(&options);
1280 /* Parse command-line arguments. */
1281 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1284 options.address_family = AF_INET;
1287 options.address_family = AF_INET6;
1290 config_file_name = optarg;
1293 if (debug_flag == 0) {
1295 options.log_level = SYSLOG_LEVEL_DEBUG1;
1296 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1297 options.log_level++;
1319 options.log_level = SYSLOG_LEVEL_QUIET;
1322 options.server_key_bits = (int)strtonum(optarg, 256,
1326 options.ports_from_cmdline = 1;
1327 if (options.num_ports >= MAX_PORTS) {
1328 fprintf(stderr, "too many ports.\n");
1331 options.ports[options.num_ports++] = a2port(optarg);
1332 if (options.ports[options.num_ports-1] <= 0) {
1333 fprintf(stderr, "Bad port number.\n");
1338 if ((options.login_grace_time = convtime(optarg)) == -1) {
1339 fprintf(stderr, "Invalid login grace time.\n");
1344 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1345 fprintf(stderr, "Invalid key regeneration interval.\n");
1350 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1351 fprintf(stderr, "too many host keys.\n");
1354 options.host_key_files[options.num_host_key_files++] =
1355 derelativise_path(optarg);
1365 while ((p = strsep(&cp, ",")) && *p != '\0') {
1366 if (strncmp(p, "addr=", 5) == 0)
1367 test_addr = xstrdup(p + 5);
1368 else if (strncmp(p, "host=", 5) == 0)
1369 test_host = xstrdup(p + 5);
1370 else if (strncmp(p, "user=", 5) == 0)
1371 test_user = xstrdup(p + 5);
1373 fprintf(stderr, "Invalid test "
1374 "mode specification %s\n", p);
1380 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1381 if (utmp_len > MAXHOSTNAMELEN) {
1382 fprintf(stderr, "Invalid utmp length.\n");
1387 line = xstrdup(optarg);
1388 if (process_server_config_line(&options, line,
1389 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1399 if (rexeced_flag || inetd_flag)
1401 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1402 fatal("sshd re-exec requires execution with an absolute path");
1404 closefrom(REEXEC_MIN_FREE_FD);
1406 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1408 SSLeay_add_all_algorithms();
1411 * Force logging to stderr until we have loaded the private host
1412 * key (unless started from inetd)
1414 log_init(__progname,
1415 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1416 SYSLOG_LEVEL_INFO : options.log_level,
1417 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1418 SYSLOG_FACILITY_AUTH : options.log_facility,
1419 log_stderr || !inetd_flag);
1422 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1423 * root's environment
1425 if (getenv("KRB5CCNAME") != NULL)
1426 unsetenv("KRB5CCNAME");
1429 /* Cray can define user privs drop all privs now!
1430 * Not needed on PRIV_SU systems!
1435 sensitive_data.server_key = NULL;
1436 sensitive_data.ssh1_host_key = NULL;
1437 sensitive_data.have_ssh1_key = 0;
1438 sensitive_data.have_ssh2_key = 0;
1441 * If we're doing an extended config test, make sure we have all of
1442 * the parameters we need. If we're not doing an extended test,
1443 * do not silently ignore connection test params.
1445 if (test_flag >= 2 &&
1446 (test_user != NULL || test_host != NULL || test_addr != NULL)
1447 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1448 fatal("user, host and addr are all required when testing "
1450 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1452 fatal("Config test connection parameter (-C) provided without "
1455 /* Fetch our configuration */
1458 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1460 load_server_config(config_file_name, &cfg);
1462 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1463 &cfg, NULL, NULL, NULL);
1467 /* Fill in default values for those options not explicitly set. */
1468 fill_default_server_options(&options);
1470 /* challenge-response is implemented via keyboard interactive */
1471 if (options.challenge_response_authentication)
1472 options.kbd_interactive_authentication = 1;
1474 /* set default channel AF */
1475 channel_set_af(options.address_family);
1477 /* Check that there are no remaining arguments. */
1479 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1483 debug("sshd version %.100s", SSH_RELEASE);
1485 /* Store privilege separation user for later use if required. */
1486 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1487 if (use_privsep || options.kerberos_authentication)
1488 fatal("Privilege separation user %s does not exist",
1491 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1492 privsep_pw = pwcopy(privsep_pw);
1493 xfree(privsep_pw->pw_passwd);
1494 privsep_pw->pw_passwd = xstrdup("*");
1498 /* load private host keys */
1499 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1501 for (i = 0; i < options.num_host_key_files; i++)
1502 sensitive_data.host_keys[i] = NULL;
1504 for (i = 0; i < options.num_host_key_files; i++) {
1505 key = key_load_private(options.host_key_files[i], "", NULL);
1506 sensitive_data.host_keys[i] = key;
1508 error("Could not load host key: %s",
1509 options.host_key_files[i]);
1510 sensitive_data.host_keys[i] = NULL;
1513 switch (key->type) {
1515 sensitive_data.ssh1_host_key = key;
1516 sensitive_data.have_ssh1_key = 1;
1520 sensitive_data.have_ssh2_key = 1;
1523 debug("private host key: #%d type %d %s", i, key->type,
1526 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1527 logit("Disabling protocol version 1. Could not load host key");
1528 options.protocol &= ~SSH_PROTO_1;
1530 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1531 logit("Disabling protocol version 2. Could not load host key");
1532 options.protocol &= ~SSH_PROTO_2;
1534 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1535 logit("sshd: no hostkeys available -- exiting.");
1539 /* Check certain values for sanity. */
1540 if (options.protocol & SSH_PROTO_1) {
1541 if (options.server_key_bits < 512 ||
1542 options.server_key_bits > 32768) {
1543 fprintf(stderr, "Bad server key size.\n");
1547 * Check that server and host key lengths differ sufficiently. This
1548 * is necessary to make double encryption work with rsaref. Oh, I
1549 * hate software patents. I dont know if this can go? Niels
1551 if (options.server_key_bits >
1552 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1553 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1554 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1555 SSH_KEY_BITS_RESERVED) {
1556 options.server_key_bits =
1557 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1558 SSH_KEY_BITS_RESERVED;
1559 debug("Forcing server key to %d bits to make it differ from host key.",
1560 options.server_key_bits);
1567 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1568 (S_ISDIR(st.st_mode) == 0))
1569 fatal("Missing privilege separation directory: %s",
1570 _PATH_PRIVSEP_CHROOT_DIR);
1573 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1574 (st.st_uid != getuid () ||
1575 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1577 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1579 fatal("%s must be owned by root and not group or "
1580 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1583 if (test_flag > 1) {
1584 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1585 parse_server_match_config(&options, test_user,
1586 test_host, test_addr);
1587 dump_config(&options);
1590 /* Configuration looks good, so exit if in test mode. */
1595 * Clear out any supplemental groups we may have inherited. This
1596 * prevents inadvertent creation of files with bad modes (in the
1597 * portable version at least, it's certainly possible for PAM
1598 * to create a file, and we can't control the code in every
1599 * module which might be used).
1601 if (setgroups(0, NULL) < 0)
1602 debug("setgroups() failed: %.200s", strerror(errno));
1605 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1606 for (i = 0; i < rexec_argc; i++) {
1607 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1608 rexec_argv[i] = saved_argv[i];
1610 rexec_argv[rexec_argc] = "-R";
1611 rexec_argv[rexec_argc + 1] = NULL;
1614 /* Ensure that umask disallows at least group and world write */
1615 new_umask = umask(0077) | 0022;
1616 (void) umask(new_umask);
1618 /* Initialize the log (it is reinitialized below in case we forked). */
1619 if (debug_flag && (!inetd_flag || rexeced_flag))
1621 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1624 * If not in debugging mode, and not started from inetd, disconnect
1625 * from the controlling terminal, and fork. The original process
1628 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1631 #endif /* TIOCNOTTY */
1632 if (daemon(0, 0) < 0)
1633 fatal("daemon() failed: %.200s", strerror(errno));
1635 /* Disconnect from the controlling tty. */
1637 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1639 (void) ioctl(fd, TIOCNOTTY, NULL);
1642 #endif /* TIOCNOTTY */
1644 /* Reinitialize the log (because of the fork above). */
1645 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1647 /* Initialize the random number generator. */
1650 /* Chdir to the root directory so that the current disk can be
1651 unmounted if desired. */
1654 /* ignore SIGPIPE */
1655 signal(SIGPIPE, SIG_IGN);
1657 /* Get a connection, either from inetd or a listening TCP socket */
1659 server_accept_inetd(&sock_in, &sock_out);
1661 platform_pre_listen();
1664 if (options.protocol & SSH_PROTO_1)
1665 generate_ephemeral_server_key();
1667 signal(SIGHUP, sighup_handler);
1668 signal(SIGCHLD, main_sigchld_handler);
1669 signal(SIGTERM, sigterm_handler);
1670 signal(SIGQUIT, sigterm_handler);
1673 * Write out the pid file after the sigterm handler
1674 * is setup and the listen sockets are bound
1677 FILE *f = fopen(options.pid_file, "w");
1680 error("Couldn't create pid file \"%s\": %s",
1681 options.pid_file, strerror(errno));
1683 fprintf(f, "%ld\n", (long) getpid());
1688 /* Accept a connection and return in a forked child */
1689 server_accept_loop(&sock_in, &sock_out,
1690 &newsock, config_s);
1693 /* This is the child processing a new connection. */
1694 setproctitle("%s", "[accepted]");
1697 * Create a new session and process group since the 4.4BSD
1698 * setlogin() affects the entire process group. We don't
1699 * want the child to be able to affect the parent.
1701 #if !defined(SSHD_ACQUIRES_CTTY)
1703 * If setsid is called, on some platforms sshd will later acquire a
1704 * controlling terminal which will result in "could not set
1705 * controlling tty" errors.
1707 if (!debug_flag && !inetd_flag && setsid() < 0)
1708 error("setsid: %.100s", strerror(errno));
1714 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1715 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1716 dup2(newsock, STDIN_FILENO);
1717 dup2(STDIN_FILENO, STDOUT_FILENO);
1718 if (startup_pipe == -1)
1719 close(REEXEC_STARTUP_PIPE_FD);
1721 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1723 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1725 if (startup_pipe != -1)
1726 close(startup_pipe);
1728 execv(rexec_argv[0], rexec_argv);
1730 /* Reexec has failed, fall back and continue */
1731 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1732 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1733 log_init(__progname, options.log_level,
1734 options.log_facility, log_stderr);
1737 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1739 close(REEXEC_CONFIG_PASS_FD);
1740 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1741 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1742 dup2(fd, STDIN_FILENO);
1743 dup2(fd, STDOUT_FILENO);
1744 if (fd > STDERR_FILENO)
1747 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1748 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1751 /* Executed child processes don't need these. */
1752 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1753 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1756 * Disable the key regeneration alarm. We will not regenerate the
1757 * key since we are no longer in a position to give it to anyone. We
1758 * will not restart on SIGHUP since it no longer makes sense.
1761 signal(SIGALRM, SIG_DFL);
1762 signal(SIGHUP, SIG_DFL);
1763 signal(SIGTERM, SIG_DFL);
1764 signal(SIGQUIT, SIG_DFL);
1765 signal(SIGCHLD, SIG_DFL);
1766 signal(SIGINT, SIG_DFL);
1769 * Register our connection. This turns encryption off because we do
1772 packet_set_connection(sock_in, sock_out);
1773 packet_set_server();
1775 /* Set SO_KEEPALIVE if requested. */
1776 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1777 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1778 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1780 if ((remote_port = get_remote_port()) < 0) {
1781 debug("get_remote_port failed");
1786 * We use get_canonical_hostname with usedns = 0 instead of
1787 * get_remote_ipaddr here so IP options will be checked.
1789 (void) get_canonical_hostname(0);
1791 * The rest of the code depends on the fact that
1792 * get_remote_ipaddr() caches the remote ip, even if
1793 * the socket goes away.
1795 remote_ip = get_remote_ipaddr();
1797 #ifdef SSH_AUDIT_EVENTS
1798 audit_connection_from(remote_ip, remote_port);
1801 allow_severity = options.log_facility|LOG_INFO;
1802 deny_severity = options.log_facility|LOG_WARNING;
1803 /* Check whether logins are denied from this host. */
1804 if (packet_connection_is_on_socket()) {
1805 struct request_info req;
1807 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1810 if (!hosts_access(&req)) {
1811 debug("Connection refused by tcp wrapper");
1814 fatal("libwrap refuse returns");
1817 #endif /* LIBWRAP */
1819 /* Log the connection. */
1820 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1823 * We don't want to listen forever unless the other side
1824 * successfully authenticates itself. So we set up an alarm which is
1825 * cleared after successful authentication. A limit of zero
1826 * indicates no limit. Note that we don't set the alarm in debugging
1827 * mode; it is just annoying to have the server exit just when you
1828 * are about to discover the bug.
1830 signal(SIGALRM, grace_alarm_handler);
1832 alarm(options.login_grace_time);
1834 sshd_exchange_identification(sock_in, sock_out);
1836 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1837 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1838 generate_ephemeral_server_key();
1840 packet_set_nonblocking();
1842 /* allocate authentication context */
1843 authctxt = xcalloc(1, sizeof(*authctxt));
1845 authctxt->loginmsg = &loginmsg;
1847 /* XXX global for cleanup, access from other modules */
1848 the_authctxt = authctxt;
1850 /* prepare buffer to collect messages to display to user after login */
1851 buffer_init(&loginmsg);
1854 if (privsep_preauth(authctxt) == 1)
1857 /* perform the key exchange */
1858 /* authenticate user and start session */
1861 do_authentication2(authctxt);
1864 do_authentication(authctxt);
1867 * If we use privilege separation, the unprivileged child transfers
1868 * the current keystate and exits
1871 mm_send_keystate(pmonitor);
1877 * Cancel the alarm we set to limit the time taken for
1881 signal(SIGALRM, SIG_DFL);
1882 authctxt->authenticated = 1;
1883 if (startup_pipe != -1) {
1884 close(startup_pipe);
1888 #ifdef SSH_AUDIT_EVENTS
1889 audit_event(SSH_AUTH_SUCCESS);
1893 if (options.gss_authentication) {
1894 temporarily_use_uid(authctxt->pw);
1895 ssh_gssapi_storecreds();
1900 if (options.use_pam) {
1907 * In privilege separation, we fork another child and prepare
1908 * file descriptor passing.
1911 privsep_postauth(authctxt);
1912 /* the monitor process [priv] will not return */
1914 destroy_sensitive_data();
1917 packet_set_timeout(options.client_alive_interval,
1918 options.client_alive_count_max);
1920 /* Start session. */
1921 do_authenticated(authctxt);
1923 /* The connection has been terminated. */
1924 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
1925 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
1926 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
1928 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
1931 if (options.use_pam)
1933 #endif /* USE_PAM */
1935 #ifdef SSH_AUDIT_EVENTS
1936 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
1948 * Decrypt session_key_int using our private server key and private host key
1949 * (key with larger modulus first).
1952 ssh1_session_key(BIGNUM *session_key_int)
1956 if (BN_cmp(sensitive_data.server_key->rsa->n,
1957 sensitive_data.ssh1_host_key->rsa->n) > 0) {
1958 /* Server key has bigger modulus. */
1959 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1960 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1961 SSH_KEY_BITS_RESERVED) {
1962 fatal("do_connection: %s: "
1963 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1964 get_remote_ipaddr(),
1965 BN_num_bits(sensitive_data.server_key->rsa->n),
1966 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1967 SSH_KEY_BITS_RESERVED);
1969 if (rsa_private_decrypt(session_key_int, session_key_int,
1970 sensitive_data.server_key->rsa) <= 0)
1972 if (rsa_private_decrypt(session_key_int, session_key_int,
1973 sensitive_data.ssh1_host_key->rsa) <= 0)
1976 /* Host key has bigger modulus (or they are equal). */
1977 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1978 BN_num_bits(sensitive_data.server_key->rsa->n) +
1979 SSH_KEY_BITS_RESERVED) {
1980 fatal("do_connection: %s: "
1981 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1982 get_remote_ipaddr(),
1983 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1984 BN_num_bits(sensitive_data.server_key->rsa->n),
1985 SSH_KEY_BITS_RESERVED);
1987 if (rsa_private_decrypt(session_key_int, session_key_int,
1988 sensitive_data.ssh1_host_key->rsa) < 0)
1990 if (rsa_private_decrypt(session_key_int, session_key_int,
1991 sensitive_data.server_key->rsa) < 0)
2004 BIGNUM *session_key_int;
2005 u_char session_key[SSH_SESSION_KEY_LENGTH];
2007 u_int cipher_type, auth_mask, protocol_flags;
2010 * Generate check bytes that the client must send back in the user
2011 * packet in order for it to be accepted; this is used to defy ip
2012 * spoofing attacks. Note that this only works against somebody
2013 * doing IP spoofing from a remote machine; any machine on the local
2014 * network can still see outgoing packets and catch the random
2015 * cookie. This only affects rhosts authentication, and this is one
2016 * of the reasons why it is inherently insecure.
2018 arc4random_buf(cookie, sizeof(cookie));
2021 * Send our public key. We include in the packet 64 bits of random
2022 * data that must be matched in the reply in order to prevent IP
2025 packet_start(SSH_SMSG_PUBLIC_KEY);
2026 for (i = 0; i < 8; i++)
2027 packet_put_char(cookie[i]);
2029 /* Store our public server RSA key. */
2030 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2031 packet_put_bignum(sensitive_data.server_key->rsa->e);
2032 packet_put_bignum(sensitive_data.server_key->rsa->n);
2034 /* Store our public host RSA key. */
2035 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2036 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2037 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2039 /* Put protocol flags. */
2040 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2042 /* Declare which ciphers we support. */
2043 packet_put_int(cipher_mask_ssh1(0));
2045 /* Declare supported authentication types. */
2047 if (options.rhosts_rsa_authentication)
2048 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2049 if (options.rsa_authentication)
2050 auth_mask |= 1 << SSH_AUTH_RSA;
2051 if (options.challenge_response_authentication == 1)
2052 auth_mask |= 1 << SSH_AUTH_TIS;
2053 if (options.password_authentication)
2054 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2055 packet_put_int(auth_mask);
2057 /* Send the packet and wait for it to be sent. */
2059 packet_write_wait();
2061 debug("Sent %d bit server key and %d bit host key.",
2062 BN_num_bits(sensitive_data.server_key->rsa->n),
2063 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2065 /* Read clients reply (cipher type and session key). */
2066 packet_read_expect(SSH_CMSG_SESSION_KEY);
2068 /* Get cipher type and check whether we accept this. */
2069 cipher_type = packet_get_char();
2071 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2072 packet_disconnect("Warning: client selects unsupported cipher.");
2074 /* Get check bytes from the packet. These must match those we
2075 sent earlier with the public key packet. */
2076 for (i = 0; i < 8; i++)
2077 if (cookie[i] != packet_get_char())
2078 packet_disconnect("IP Spoofing check bytes do not match.");
2080 debug("Encryption type: %.200s", cipher_name(cipher_type));
2082 /* Get the encrypted integer. */
2083 if ((session_key_int = BN_new()) == NULL)
2084 fatal("do_ssh1_kex: BN_new failed");
2085 packet_get_bignum(session_key_int);
2087 protocol_flags = packet_get_int();
2088 packet_set_protocol_flags(protocol_flags);
2091 /* Decrypt session_key_int using host/server keys */
2092 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2095 * Extract session key from the decrypted integer. The key is in the
2096 * least significant 256 bits of the integer; the first byte of the
2097 * key is in the highest bits.
2100 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2101 len = BN_num_bytes(session_key_int);
2102 if (len < 0 || (u_int)len > sizeof(session_key)) {
2103 error("do_ssh1_kex: bad session key len from %s: "
2104 "session_key_int %d > sizeof(session_key) %lu",
2105 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2108 memset(session_key, 0, sizeof(session_key));
2109 BN_bn2bin(session_key_int,
2110 session_key + sizeof(session_key) - len);
2112 derive_ssh1_session_id(
2113 sensitive_data.ssh1_host_key->rsa->n,
2114 sensitive_data.server_key->rsa->n,
2115 cookie, session_id);
2117 * Xor the first 16 bytes of the session key with the
2120 for (i = 0; i < 16; i++)
2121 session_key[i] ^= session_id[i];
2125 int bytes = BN_num_bytes(session_key_int);
2126 u_char *buf = xmalloc(bytes);
2129 logit("do_connection: generating a fake encryption key");
2130 BN_bn2bin(session_key_int, buf);
2132 MD5_Update(&md, buf, bytes);
2133 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2134 MD5_Final(session_key, &md);
2136 MD5_Update(&md, session_key, 16);
2137 MD5_Update(&md, buf, bytes);
2138 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2139 MD5_Final(session_key + 16, &md);
2140 memset(buf, 0, bytes);
2142 for (i = 0; i < 16; i++)
2143 session_id[i] = session_key[i] ^ session_key[i + 16];
2145 /* Destroy the private and public keys. No longer. */
2146 destroy_sensitive_data();
2149 mm_ssh1_session_id(session_id);
2151 /* Destroy the decrypted integer. It is no longer needed. */
2152 BN_clear_free(session_key_int);
2154 /* Set the session key. From this on all communications will be encrypted. */
2155 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2157 /* Destroy our copy of the session key. It is no longer needed. */
2158 memset(session_key, 0, sizeof(session_key));
2160 debug("Received session key; encryption turned on.");
2162 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2163 packet_start(SSH_SMSG_SUCCESS);
2165 packet_write_wait();
2169 * SSH2 key exchange: diffie-hellman-group1-sha1
2176 if (options.ciphers != NULL) {
2177 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2178 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2180 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2181 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2182 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2183 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2185 if (options.macs != NULL) {
2186 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2187 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2189 if (options.compression == COMP_NONE) {
2190 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2191 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2192 } else if (options.compression == COMP_DELAYED) {
2193 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2194 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2197 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2199 /* start key exchange */
2200 kex = kex_setup(myproposal);
2201 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2202 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2203 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2204 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2206 kex->client_version_string=client_version_string;
2207 kex->server_version_string=server_version_string;
2208 kex->load_host_key=&get_hostkey_by_type;
2209 kex->host_key_index=&get_hostkey_index;
2213 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2215 session_id2 = kex->session_id;
2216 session_id2_len = kex->session_id_len;
2219 /* send 1st encrypted/maced/compressed message */
2220 packet_start(SSH2_MSG_IGNORE);
2221 packet_put_cstring("markus");
2223 packet_write_wait();
2228 /* server specific fatal cleanup */
2233 do_cleanup(the_authctxt);
2234 #ifdef SSH_AUDIT_EVENTS
2235 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2236 if (!use_privsep || mm_is_monitor())
2237 audit_event(SSH_CONNECTION_ABANDON);