2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * Created: Fri Mar 17 17:09:28 1995 ylo
6 * This program is the ssh daemon. It listens for connections from clients, and
7 * 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 authentication
12 * SSH2 implementation,
13 * Copyright (c) 2000 Markus Friedl. All rights reserved.
17 RCSID("$OpenBSD: sshd.c,v 1.103 2000/04/12 08:11:36 markus Exp $");
33 # include <openssl/dh.h>
34 # include <openssl/bn.h>
35 # include <openssl/hmac.h>
36 # include <openssl/dsa.h>
37 # include <openssl/rsa.h>
42 # include <ssl/hmac.h>
51 #include "myproposal.h"
56 int allow_severity = LOG_INFO;
57 int deny_severity = LOG_WARNING;
64 /* Server configuration options. */
65 ServerOptions options;
67 /* Name of the server configuration file. */
68 char *config_file_name = SERVER_CONFIG_FILE;
71 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
72 * Default value is AF_UNSPEC means both IPv4 and IPv6.
75 int IPv4or6 = AF_INET;
77 int IPv4or6 = AF_UNSPEC;
81 * Debug mode flag. This can be set on the command line. If debug
82 * mode is enabled, extra debugging output will be sent to the system
83 * log, the daemon will not go to background, and will exit after processing
84 * the first connection.
88 /* Flag indicating that the daemon is being started from inetd. */
91 /* debug goes to stderr unless inetd_flag is set */
94 /* argv[0] without path. */
97 /* Saved arguments to main(). */
101 * The sockets that the server is listening; this is used in the SIGHUP
104 #define MAX_LISTEN_SOCKS 16
105 int listen_socks[MAX_LISTEN_SOCKS];
106 int num_listen_socks = 0;
109 * the client's version string, passed by sshd2 in compat mode. if != NULL,
110 * sshd will skip the version-number exchange
112 char *client_version_string = NULL;
113 char *server_version_string = NULL;
116 * Any really sensitive data in the application is contained in this
117 * structure. The idea is that this structure could be locked into memory so
118 * that the pages do not get written into swap. However, there are some
119 * problems. The private key contains BIGNUMs, and we do not (in principle)
120 * have access to the internals of them, and locking just the structure is
121 * not very useful. Currently, memory locking is not implemented.
124 RSA *private_key; /* Private part of server key. */
125 RSA *host_key; /* Private part of host key. */
129 * Flag indicating whether the current session key has been used. This flag
130 * is set whenever the key is used, and cleared when the key is regenerated.
134 /* This is set to true when SIGHUP is received. */
135 int received_sighup = 0;
137 /* Public side of the server key. This value is regenerated regularly with
141 /* session identifier, used by RSA-auth */
142 unsigned char session_id[16];
144 /* Prototypes for various functions defined later in this file. */
149 * Close all listening sockets
152 close_listen_socks(void)
155 for (i = 0; i < num_listen_socks; i++)
156 close(listen_socks[i]);
157 num_listen_socks = -1;
161 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
162 * the effect is to reread the configuration file (and to regenerate
166 sighup_handler(int sig)
169 signal(SIGHUP, sighup_handler);
173 * Called from the main program after receiving SIGHUP.
174 * Restarts the server.
179 log("Received SIGHUP; restarting.");
180 close_listen_socks();
181 execv(saved_argv[0], saved_argv);
182 log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno));
187 * Generic signal handler for terminating signals in the master daemon.
188 * These close the listen socket; not closing it seems to cause "Address
189 * already in use" problems on some machines, which is inconvenient.
192 sigterm_handler(int sig)
194 log("Received signal %d; terminating.", sig);
195 close_listen_socks();
200 * SIGCHLD handler. This is called whenever a child dies. This will then
201 * reap any zombies left by exited c.
204 main_sigchld_handler(int sig)
206 int save_errno = errno;
209 while (waitpid(-1, &status, WNOHANG) > 0)
212 signal(SIGCHLD, main_sigchld_handler);
217 * Signal handler for the alarm after the login grace period has expired.
220 grace_alarm_handler(int sig)
222 /* Close the connection. */
225 /* Log error and exit. */
226 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
230 * Signal handler for the key regeneration alarm. Note that this
231 * alarm only occurs in the daemon waiting for connections, and it does not
232 * do anything with the private key or random state before forking.
233 * Thus there should be no concurrency control/asynchronous execution
237 key_regeneration_alarm(int sig)
239 int save_errno = errno;
241 /* Check if we should generate a new key. */
243 /* This should really be done in the background. */
244 log("Generating new %d bit RSA key.", options.server_key_bits);
246 if (sensitive_data.private_key != NULL)
247 RSA_free(sensitive_data.private_key);
248 sensitive_data.private_key = RSA_new();
250 if (public_key != NULL)
251 RSA_free(public_key);
252 public_key = RSA_new();
254 rsa_generate_key(sensitive_data.private_key, public_key,
255 options.server_key_bits);
258 log("RSA key generation complete.");
260 /* Reschedule the alarm. */
261 signal(SIGALRM, key_regeneration_alarm);
262 alarm(options.key_regeneration_time);
271 if(*t == '\n' || *t == '\r') {
282 sshd_exchange_identification(int sock_in, int sock_out)
285 int remote_major, remote_minor;
288 char buf[256]; /* Must not be larger than remote_version. */
289 char remote_version[256]; /* Must be at least as big as buf. */
291 if ((options.protocol & SSH_PROTO_1) &&
292 (options.protocol & SSH_PROTO_2)) {
293 major = PROTOCOL_MAJOR_1;
295 } else if (options.protocol & SSH_PROTO_2) {
296 major = PROTOCOL_MAJOR_2;
297 minor = PROTOCOL_MINOR_2;
299 major = PROTOCOL_MAJOR_1;
300 minor = PROTOCOL_MINOR_1;
302 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
303 server_version_string = xstrdup(buf);
305 if (client_version_string == NULL) {
306 /* Send our protocol version identification. */
307 if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
308 != strlen(server_version_string)) {
309 log("Could not write ident string to %s.", get_remote_ipaddr());
313 /* Read other side\'s version identification. */
314 for (i = 0; i < sizeof(buf) - 1; i++) {
315 if (read(sock_in, &buf[i], 1) != 1) {
316 log("Did not receive ident string from %s.", get_remote_ipaddr());
319 if (buf[i] == '\r') {
324 if (buf[i] == '\n') {
330 buf[sizeof(buf) - 1] = 0;
331 client_version_string = xstrdup(buf);
335 * Check that the versions match. In future this might accept
336 * several versions and set appropriate flags to handle them.
338 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
339 &remote_major, &remote_minor, remote_version) != 3) {
340 s = "Protocol mismatch.\n";
341 (void) atomicio(write, sock_out, s, strlen(s));
344 log("Bad protocol version identification '%.100s' from %s",
345 client_version_string, get_remote_ipaddr());
348 debug("Client protocol version %d.%d; client software version %.100s",
349 remote_major, remote_minor, remote_version);
351 compat_datafellows(remote_version);
354 switch(remote_major) {
356 if (!(options.protocol & SSH_PROTO_1)) {
360 if (remote_minor < 3) {
361 packet_disconnect("Your ssh version is too old and"
362 "is no longer supported. Please install a newer version.");
363 } else if (remote_minor == 3) {
364 /* note that this disables agent-forwarding */
367 if (remote_minor == 99) {
368 if (options.protocol & SSH_PROTO_2)
375 if (options.protocol & SSH_PROTO_2) {
384 chop(server_version_string);
385 chop(client_version_string);
386 debug("Local version string %.200s", server_version_string);
389 s = "Protocol major versions differ.\n";
390 (void) atomicio(write, sock_out, s, strlen(s));
393 log("Protocol major versions differ for %s: %.200s vs. %.200s",
395 server_version_string, client_version_string);
401 * Main program for the daemon.
404 main(int ac, char **av)
408 int opt, sock_in = 0, sock_out = 0, newsock, i, fdsetsz, pid, on = 1;
412 struct sockaddr_storage from;
413 const char *remote_ip;
417 struct linger linger;
419 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
420 int listen_sock, maxfd;
424 if (strchr(av[0], '/'))
425 av0 = strrchr(av[0], '/') + 1;
429 /* Initialize configuration options to their default values. */
430 initialize_server_options(&options);
432 /* Parse command-line arguments. */
433 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:diqQ46")) != EOF) {
442 config_file_name = optarg;
446 options.log_level = SYSLOG_LEVEL_DEBUG;
455 options.log_level = SYSLOG_LEVEL_QUIET;
458 options.server_key_bits = atoi(optarg);
461 options.ports_from_cmdline = 1;
462 if (options.num_ports >= MAX_PORTS)
463 fatal("too many ports.\n");
464 options.ports[options.num_ports++] = atoi(optarg);
467 options.login_grace_time = atoi(optarg);
470 options.key_regeneration_time = atoi(optarg);
473 options.host_key_file = optarg;
476 client_version_string = optarg;
477 /* only makes sense with inetd_flag, i.e. no listen() */
482 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
483 fprintf(stderr, "Usage: %s [options]\n", av0);
484 fprintf(stderr, "Options:\n");
485 fprintf(stderr, " -f file Configuration file (default %s)\n", SERVER_CONFIG_FILE);
486 fprintf(stderr, " -d Debugging mode\n");
487 fprintf(stderr, " -i Started from inetd\n");
488 fprintf(stderr, " -q Quiet (no logging)\n");
489 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
490 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
491 fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n");
492 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
493 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
495 fprintf(stderr, " -4 Use IPv4 only\n");
496 fprintf(stderr, " -6 Use IPv6 only\n");
502 * Force logging to stderr until we have loaded the private host
503 * key (unless started from inetd)
506 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
507 options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
510 /* check if RSA support exists */
511 if (rsa_alive() == 0) {
513 printf("sshd: no RSA support in libssl and libcrypto -- exiting. See ssl(8)\n");
514 log("no RSA support in libssl and libcrypto -- exiting. See ssl(8)");
517 /* Read server configuration options from the configuration file. */
518 read_server_config(&options, config_file_name);
520 /* Fill in default values for those options not explicitly set. */
521 fill_default_server_options(&options);
523 /* Check certain values for sanity. */
524 if (options.server_key_bits < 512 ||
525 options.server_key_bits > 32768) {
526 fprintf(stderr, "Bad server key size.\n");
529 /* Check that there are no remaining arguments. */
531 fprintf(stderr, "Extra argument %s.\n", av[optind]);
535 debug("sshd version %.100s", SSH_VERSION);
537 sensitive_data.host_key = RSA_new();
539 /* Load the host key. It must have empty passphrase. */
540 if (!load_private_key(options.host_key_file, "",
541 sensitive_data.host_key, &comment)) {
542 error("Could not load host key: %.200s: %.100s",
543 options.host_key_file, strerror(errno));
548 /* Initialize the log (it is reinitialized below in case we
550 if (debug_flag && !inetd_flag)
552 log_init(av0, options.log_level, options.log_facility, log_stderr);
554 /* If not in debugging mode, and not started from inetd,
555 disconnect from the controlling terminal, and fork. The
556 original process exits. */
557 if (!debug_flag && !inetd_flag) {
560 #endif /* TIOCNOTTY */
561 if (daemon(0, 0) < 0)
562 fatal("daemon() failed: %.200s", strerror(errno));
564 /* Disconnect from the controlling tty. */
566 fd = open("/dev/tty", O_RDWR | O_NOCTTY);
568 (void) ioctl(fd, TIOCNOTTY, NULL);
571 #endif /* TIOCNOTTY */
573 /* Reinitialize the log (because of the fork above). */
574 log_init(av0, options.log_level, options.log_facility, log_stderr);
576 /* Check that server and host key lengths differ sufficiently.
577 This is necessary to make double encryption work with rsaref.
578 Oh, I hate software patents. I dont know if this can go? Niels */
579 if (options.server_key_bits >
580 BN_num_bits(sensitive_data.host_key->n) - SSH_KEY_BITS_RESERVED &&
581 options.server_key_bits <
582 BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) {
583 options.server_key_bits =
584 BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED;
585 debug("Forcing server key to %d bits to make it differ from host key.",
586 options.server_key_bits);
588 /* Do not display messages to stdout in RSA code. */
591 /* Initialize the random number generator. */
594 /* Chdir to the root directory so that the current disk can be
595 unmounted if desired. */
598 /* Start listening for a socket, unless started from inetd. */
601 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
605 /* We intentionally do not close the descriptors 0, 1, and 2
606 as our code for setting the descriptors won\'t work
607 if ttyfd happens to be one of those. */
608 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
610 public_key = RSA_new();
611 sensitive_data.private_key = RSA_new();
613 /* XXX check options.protocol */
614 log("Generating %d bit RSA key.", options.server_key_bits);
615 rsa_generate_key(sensitive_data.private_key, public_key,
616 options.server_key_bits);
618 log("RSA key generation complete.");
620 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
621 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
623 if (num_listen_socks >= MAX_LISTEN_SOCKS)
624 fatal("Too many listen sockets. "
625 "Enlarge MAX_LISTEN_SOCKS");
626 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
627 ntop, sizeof(ntop), strport, sizeof(strport),
628 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
629 error("getnameinfo failed");
632 /* Create socket for listening. */
633 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
634 if (listen_sock < 0) {
635 /* kernel may not support ipv6 */
636 verbose("socket: %.100s", strerror(errno));
639 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
640 error("listen_sock O_NONBLOCK: %s", strerror(errno));
645 * Set socket options. We try to make the port
646 * reusable and have it close as fast as possible
647 * without waiting in unnecessary wait states on
650 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
651 (void *) &on, sizeof(on));
654 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
655 (void *) &linger, sizeof(linger));
657 debug("Bind to port %s on %s.", strport, ntop);
659 /* Bind the socket to the desired port. */
660 if ((bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) &&
662 error("Bind to port %s on %s failed: %.200s.",
663 strport, ntop, strerror(errno));
667 listen_socks[num_listen_socks] = listen_sock;
670 /* Start listening on the port. */
671 log("Server listening on %s port %s.", ntop, strport);
672 if (listen(listen_sock, 5) < 0)
673 fatal("listen: %.100s", strerror(errno));
676 freeaddrinfo(options.listen_addrs);
678 if (!num_listen_socks)
679 fatal("Cannot bind any address.");
683 * Record our pid in /etc/sshd_pid to make it easier
684 * to kill the correct sshd. We don\'t want to do
685 * this before the bind above because the bind will
686 * fail if there already is a daemon, and this will
687 * overwrite any old pid in the file.
689 f = fopen(SSH_DAEMON_PID_FILE, "w");
691 fprintf(f, "%u\n", (unsigned int) getpid());
696 public_key = RSA_new();
697 sensitive_data.private_key = RSA_new();
699 log("Generating %d bit RSA key.", options.server_key_bits);
700 rsa_generate_key(sensitive_data.private_key, public_key,
701 options.server_key_bits);
703 log("RSA key generation complete.");
705 /* Schedule server key regeneration alarm. */
706 signal(SIGALRM, key_regeneration_alarm);
707 alarm(options.key_regeneration_time);
709 /* Arrange to restart on SIGHUP. The handler needs listen_sock. */
710 signal(SIGHUP, sighup_handler);
711 signal(SIGTERM, sigterm_handler);
712 signal(SIGQUIT, sigterm_handler);
714 /* Arrange SIGCHLD to be caught. */
715 signal(SIGCHLD, main_sigchld_handler);
717 /* setup fd set for listen */
719 for (i = 0; i < num_listen_socks; i++)
720 if (listen_socks[i] > maxfd)
721 maxfd = listen_socks[i];
722 fdsetsz = howmany(maxfd, NFDBITS) * sizeof(fd_mask);
723 fdset = (fd_set *)xmalloc(fdsetsz);
726 * Stay listening for connections until the system crashes or
727 * the daemon is killed with a signal.
732 /* Wait in select until there is a connection. */
733 memset(fdset, 0, fdsetsz);
734 for (i = 0; i < num_listen_socks; i++)
735 FD_SET(listen_socks[i], fdset);
736 if (select(maxfd + 1, fdset, NULL, NULL, NULL) < 0) {
738 error("select: %.100s", strerror(errno));
741 for (i = 0; i < num_listen_socks; i++) {
742 if (!FD_ISSET(listen_socks[i], fdset))
744 fromlen = sizeof(from);
745 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
748 if (errno != EINTR && errno != EWOULDBLOCK)
749 error("accept: %.100s", strerror(errno));
752 if (fcntl(newsock, F_SETFL, 0) < 0) {
753 error("newsock del O_NONBLOCK: %s", strerror(errno));
757 * Got connection. Fork a child to handle it, unless
758 * we are in debugging mode.
762 * In debugging mode. Close the listening
763 * socket, and start processing the
764 * connection without forking.
766 debug("Server will not fork when running in debugging mode.");
767 close_listen_socks();
774 * Normal production daemon. Fork, and have
775 * the child process the connection. The
776 * parent continues listening.
778 if ((pid = fork()) == 0) {
780 * Child. Close the listening socket, and start using the
781 * accepted socket. Reinitialize logging (since our pid has
782 * changed). We break out of the loop to handle the connection.
784 close_listen_socks();
787 log_init(av0, options.log_level, options.log_facility, log_stderr);
792 /* Parent. Stay in the loop. */
794 error("fork: %.100s", strerror(errno));
796 debug("Forked child %d.", pid);
798 /* Mark that the key has been used (it was "given" to the child). */
803 /* Close the new socket (the child is now taking care of it). */
805 } /* for (i = 0; i < num_listen_socks; i++) */
806 /* child process check (or debug mode) */
807 if (num_listen_socks < 0)
812 /* This is the child processing a new connection. */
815 * Disable the key regeneration alarm. We will not regenerate the
816 * key since we are no longer in a position to give it to anyone. We
817 * will not restart on SIGHUP since it no longer makes sense.
820 signal(SIGALRM, SIG_DFL);
821 signal(SIGHUP, SIG_DFL);
822 signal(SIGTERM, SIG_DFL);
823 signal(SIGQUIT, SIG_DFL);
824 signal(SIGCHLD, SIG_DFL);
827 * Set socket options for the connection. We want the socket to
828 * close as fast as possible without waiting for anything. If the
829 * connection is not a socket, these will do nothing.
831 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
834 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
837 * Register our connection. This turns encryption off because we do
840 packet_set_connection(sock_in, sock_out);
842 remote_port = get_remote_port();
843 remote_ip = get_remote_ipaddr();
845 /* Check whether logins are denied from this host. */
847 /* XXX LIBWRAP noes not know about IPv6 */
849 struct request_info req;
851 request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL);
854 if (!hosts_access(&req)) {
859 /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
862 /* Log the connection. */
863 verbose("Connection from %.500s port %d", remote_ip, remote_port);
866 * We don\'t want to listen forever unless the other side
867 * successfully authenticates itself. So we set up an alarm which is
868 * cleared after successful authentication. A limit of zero
869 * indicates no limit. Note that we don\'t set the alarm in debugging
870 * mode; it is just annoying to have the server exit just when you
871 * are about to discover the bug.
873 signal(SIGALRM, grace_alarm_handler);
875 alarm(options.login_grace_time);
877 sshd_exchange_identification(sock_in, sock_out);
879 * Check that the connection comes from a privileged port. Rhosts-
880 * and Rhosts-RSA-Authentication only make sense from priviledged
881 * programs. Of course, if the intruder has root access on his local
882 * machine, he can connect from any port. So do not use these
883 * authentication methods from machines that you do not trust.
885 if (remote_port >= IPPORT_RESERVED ||
886 remote_port < IPPORT_RESERVED / 2) {
887 options.rhosts_authentication = 0;
888 options.rhosts_rsa_authentication = 0;
891 if (!packet_connection_is_ipv4() &&
892 options.kerberos_authentication) {
893 debug("Kerberos Authentication disabled, only available for IPv4.");
894 options.kerberos_authentication = 0;
898 packet_set_nonblocking();
900 /* perform the key exchange */
901 /* authenticate user and start session */
904 do_authentication2();
911 /* Cleanup user's ticket cache file. */
912 if (options.kerberos_ticket_cleanup)
916 /* The connection has been terminated. */
917 verbose("Closing connection to %.100s", remote_ip);
935 BIGNUM *session_key_int;
936 unsigned char session_key[SSH_SESSION_KEY_LENGTH];
937 unsigned char cookie[8];
938 unsigned int cipher_type, auth_mask, protocol_flags;
942 * Generate check bytes that the client must send back in the user
943 * packet in order for it to be accepted; this is used to defy ip
944 * spoofing attacks. Note that this only works against somebody
945 * doing IP spoofing from a remote machine; any machine on the local
946 * network can still see outgoing packets and catch the random
947 * cookie. This only affects rhosts authentication, and this is one
948 * of the reasons why it is inherently insecure.
950 for (i = 0; i < 8; i++) {
953 cookie[i] = rand & 0xff;
958 * Send our public key. We include in the packet 64 bits of random
959 * data that must be matched in the reply in order to prevent IP
962 packet_start(SSH_SMSG_PUBLIC_KEY);
963 for (i = 0; i < 8; i++)
964 packet_put_char(cookie[i]);
966 /* Store our public server RSA key. */
967 packet_put_int(BN_num_bits(public_key->n));
968 packet_put_bignum(public_key->e);
969 packet_put_bignum(public_key->n);
971 /* Store our public host RSA key. */
972 packet_put_int(BN_num_bits(sensitive_data.host_key->n));
973 packet_put_bignum(sensitive_data.host_key->e);
974 packet_put_bignum(sensitive_data.host_key->n);
976 /* Put protocol flags. */
977 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
979 /* Declare which ciphers we support. */
980 packet_put_int(cipher_mask1());
982 /* Declare supported authentication types. */
984 if (options.rhosts_authentication)
985 auth_mask |= 1 << SSH_AUTH_RHOSTS;
986 if (options.rhosts_rsa_authentication)
987 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
988 if (options.rsa_authentication)
989 auth_mask |= 1 << SSH_AUTH_RSA;
991 if (options.kerberos_authentication)
992 auth_mask |= 1 << SSH_AUTH_KERBEROS;
995 if (options.kerberos_tgt_passing)
996 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
997 if (options.afs_token_passing)
998 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1001 if (options.skey_authentication == 1)
1002 auth_mask |= 1 << SSH_AUTH_TIS;
1004 if (options.password_authentication)
1005 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1006 packet_put_int(auth_mask);
1008 /* Send the packet and wait for it to be sent. */
1010 packet_write_wait();
1012 debug("Sent %d bit public key and %d bit host key.",
1013 BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n));
1015 /* Read clients reply (cipher type and session key). */
1016 packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
1018 /* Get cipher type and check whether we accept this. */
1019 cipher_type = packet_get_char();
1021 if (!(cipher_mask() & (1 << cipher_type)))
1022 packet_disconnect("Warning: client selects unsupported cipher.");
1024 /* Get check bytes from the packet. These must match those we
1025 sent earlier with the public key packet. */
1026 for (i = 0; i < 8; i++)
1027 if (cookie[i] != packet_get_char())
1028 packet_disconnect("IP Spoofing check bytes do not match.");
1030 debug("Encryption type: %.200s", cipher_name(cipher_type));
1032 /* Get the encrypted integer. */
1033 session_key_int = BN_new();
1034 packet_get_bignum(session_key_int, &slen);
1036 protocol_flags = packet_get_int();
1037 packet_set_protocol_flags(protocol_flags);
1039 packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
1042 * Decrypt it using our private server key and private host key (key
1043 * with larger modulus first).
1045 if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) {
1046 /* Private key has bigger modulus. */
1047 if (BN_num_bits(sensitive_data.private_key->n) <
1048 BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) {
1049 fatal("do_connection: %s: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1050 get_remote_ipaddr(),
1051 BN_num_bits(sensitive_data.private_key->n),
1052 BN_num_bits(sensitive_data.host_key->n),
1053 SSH_KEY_BITS_RESERVED);
1055 rsa_private_decrypt(session_key_int, session_key_int,
1056 sensitive_data.private_key);
1057 rsa_private_decrypt(session_key_int, session_key_int,
1058 sensitive_data.host_key);
1060 /* Host key has bigger modulus (or they are equal). */
1061 if (BN_num_bits(sensitive_data.host_key->n) <
1062 BN_num_bits(sensitive_data.private_key->n) + SSH_KEY_BITS_RESERVED) {
1063 fatal("do_connection: %s: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d",
1064 get_remote_ipaddr(),
1065 BN_num_bits(sensitive_data.host_key->n),
1066 BN_num_bits(sensitive_data.private_key->n),
1067 SSH_KEY_BITS_RESERVED);
1069 rsa_private_decrypt(session_key_int, session_key_int,
1070 sensitive_data.host_key);
1071 rsa_private_decrypt(session_key_int, session_key_int,
1072 sensitive_data.private_key);
1075 compute_session_id(session_id, cookie,
1076 sensitive_data.host_key->n,
1077 sensitive_data.private_key->n);
1079 /* Destroy the private and public keys. They will no longer be needed. */
1080 RSA_free(public_key);
1081 RSA_free(sensitive_data.private_key);
1082 RSA_free(sensitive_data.host_key);
1085 * Extract session key from the decrypted integer. The key is in the
1086 * least significant 256 bits of the integer; the first byte of the
1087 * key is in the highest bits.
1089 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1090 len = BN_num_bytes(session_key_int);
1091 if (len < 0 || len > sizeof(session_key))
1092 fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d",
1093 get_remote_ipaddr(),
1094 len, sizeof(session_key));
1095 memset(session_key, 0, sizeof(session_key));
1096 BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len);
1098 /* Destroy the decrypted integer. It is no longer needed. */
1099 BN_clear_free(session_key_int);
1101 /* Xor the first 16 bytes of the session key with the session id. */
1102 for (i = 0; i < 16; i++)
1103 session_key[i] ^= session_id[i];
1105 /* Set the session key. From this on all communications will be encrypted. */
1106 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1108 /* Destroy our copy of the session key. It is no longer needed. */
1109 memset(session_key, 0, sizeof(session_key));
1111 debug("Received session key; encryption turned on.");
1113 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1114 packet_start(SSH_SMSG_SUCCESS);
1116 packet_write_wait();
1120 * SSH2 key exchange: diffie-hellman-group1-sha1
1125 Buffer *server_kexinit;
1126 Buffer *client_kexinit;
1127 int payload_len, dlen;
1129 unsigned int klen, kout;
1131 unsigned char *signature = NULL;
1132 unsigned char *server_host_key_blob = NULL;
1133 unsigned int sbloblen;
1135 BIGNUM *dh_client_pub = 0;
1136 BIGNUM *shared_secret = 0;
1138 unsigned char *kbuf;
1139 unsigned char *hash;
1141 Key *server_host_key;
1142 char *cprop[PROPOSAL_MAX];
1143 char *sprop[PROPOSAL_MAX];
1147 if (options.ciphers != NULL) {
1148 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1149 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1152 debug("Sending KEX init.");
1154 for (i = 0; i < PROPOSAL_MAX; i++)
1155 sprop[i] = xstrdup(myproposal[i]);
1156 server_kexinit = kex_init(sprop);
1157 packet_start(SSH2_MSG_KEXINIT);
1158 packet_put_raw(buffer_ptr(server_kexinit), buffer_len(server_kexinit));
1160 packet_write_wait();
1164 packet_read_expect(&payload_len, SSH2_MSG_KEXINIT);
1167 * save raw KEXINIT payload in buffer. this is used during
1168 * computation of the session_id and the session keys.
1170 client_kexinit = xmalloc(sizeof(*client_kexinit));
1171 buffer_init(client_kexinit);
1172 ptr = packet_get_raw(&payload_len);
1173 buffer_append(client_kexinit, ptr, payload_len);
1176 for (i = 0; i < 16; i++)
1177 (void) packet_get_char();
1178 /* save kex init proposal strings */
1179 for (i = 0; i < PROPOSAL_MAX; i++) {
1180 cprop[i] = packet_get_string(NULL);
1181 debug("got kexinit string: %s", cprop[i]);
1184 i = (int) packet_get_char();
1185 debug("first kex follow == %d", i);
1186 i = packet_get_int();
1187 debug("reserved == %d", i);
1189 debug("done read kexinit");
1190 kex = kex_choose_conf(cprop, sprop, 1);
1194 debug("Wait SSH2_MSG_KEXDH_INIT.");
1195 packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
1198 dh_client_pub = BN_new();
1199 if (dh_client_pub == NULL)
1200 fatal("dh_client_pub == NULL");
1201 packet_get_bignum2(dh_client_pub, &dlen);
1204 fprintf(stderr, "\ndh_client_pub= ");
1205 bignum_print(dh_client_pub);
1206 fprintf(stderr, "\n");
1207 debug("bits %d", BN_num_bits(dh_client_pub));
1210 /* generate DH key */
1211 dh = dh_new_group1(); /* XXX depends on 'kex' */
1214 fprintf(stderr, "\np= ");
1215 bignum_print(dh->p);
1216 fprintf(stderr, "\ng= ");
1217 bignum_print(dh->g);
1218 fprintf(stderr, "\npub= ");
1219 bignum_print(dh->pub_key);
1220 fprintf(stderr, "\n");
1222 if (!dh_pub_is_valid(dh, dh_client_pub))
1223 packet_disconnect("bad client public DH value");
1226 kbuf = xmalloc(klen);
1227 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1230 debug("shared secret: len %d/%d", klen, kout);
1231 fprintf(stderr, "shared secret == ");
1232 for (i = 0; i< kout; i++)
1233 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1234 fprintf(stderr, "\n");
1236 shared_secret = BN_new();
1238 BN_bin2bn(kbuf, kout, shared_secret);
1239 memset(kbuf, 0, klen);
1242 server_host_key = dsa_get_serverkey(options.dsa_key_file);
1243 dsa_make_serverkey_blob(server_host_key, &server_host_key_blob, &sbloblen);
1245 /* calc H */ /* XXX depends on 'kex' */
1247 client_version_string,
1248 server_version_string,
1249 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1250 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1251 (char *)server_host_key_blob, sbloblen,
1256 buffer_free(client_kexinit);
1257 buffer_free(server_kexinit);
1258 xfree(client_kexinit);
1259 xfree(server_kexinit);
1261 fprintf(stderr, "hash == ");
1262 for (i = 0; i< 20; i++)
1263 fprintf(stderr, "%02x", (hash[i])&0xff);
1264 fprintf(stderr, "\n");
1267 dsa_sign(server_host_key, &signature, &slen, hash, 20);
1268 /* hashlen depends on KEX */
1269 key_free(server_host_key);
1271 /* send server hostkey, DH pubkey 'f' and singed H */
1272 packet_start(SSH2_MSG_KEXDH_REPLY);
1273 packet_put_string((char *)server_host_key_blob, sbloblen);
1274 packet_put_bignum2(dh->pub_key); // f
1275 packet_put_string((char *)signature, slen);
1277 packet_write_wait();
1279 kex_derive_keys(kex, hash, shared_secret);
1280 packet_set_kex(kex);
1282 /* have keys, free DH */
1285 debug("send SSH2_MSG_NEWKEYS.");
1286 packet_start(SSH2_MSG_NEWKEYS);
1288 packet_write_wait();
1289 debug("done: send SSH2_MSG_NEWKEYS.");
1291 debug("Wait SSH2_MSG_NEWKEYS.");
1292 packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1293 debug("GOT SSH2_MSG_NEWKEYS.");
1296 /* send 1st encrypted/maced/compressed message */
1297 packet_start(SSH2_MSG_IGNORE);
1298 packet_put_cstring("markus");
1300 packet_write_wait();
1302 debug("done: KEX2.");