2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * This program is the ssh daemon. It listens for connections from clients,
6 * and performs authentication, executes use commands or shell, and forwards
7 * information to/from the application to the user client over an encrypted
8 * connection. This can also handle forwarding of X11, TCP/IP, and
9 * authentication agent connections.
11 * As far as I am concerned, the code I have written for this software
12 * can be used freely for any purpose. Any derived versions of this
13 * software must be clearly marked as such, and if the derived work is
14 * incompatible with the protocol description in the RFC file, it must be
15 * called by a name other than "ssh" or "Secure Shell".
17 * SSH2 implementation:
19 * Copyright (c) 2000 Markus Friedl. All rights reserved.
21 * Redistribution and use in source and binary forms, with or without
22 * modification, are permitted provided that the following conditions
24 * 1. Redistributions of source code must retain the above copyright
25 * notice, this list of conditions and the following disclaimer.
26 * 2. Redistributions in binary form must reproduce the above copyright
27 * notice, this list of conditions and the following disclaimer in the
28 * documentation and/or other materials provided with the distribution.
30 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
31 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
33 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
34 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
35 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
39 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
43 RCSID("$OpenBSD: sshd.c,v 1.173 2001/03/05 17:17:21 markus Exp $");
45 #include <openssl/dh.h>
46 #include <openssl/bn.h>
47 #include <openssl/hmac.h>
66 #include "myproposal.h"
68 #include "pathnames.h"
77 int allow_severity = LOG_INFO;
78 int deny_severity = LOG_WARNING;
85 #ifdef HAVE___PROGNAME
86 extern char *__progname;
91 /* Server configuration options. */
92 ServerOptions options;
94 /* Name of the server configuration file. */
95 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
98 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
99 * Default value is AF_UNSPEC means both IPv4 and IPv6.
102 int IPv4or6 = AF_INET;
104 int IPv4or6 = AF_UNSPEC;
108 * Debug mode flag. This can be set on the command line. If debug
109 * mode is enabled, extra debugging output will be sent to the system
110 * log, the daemon will not go to background, and will exit after processing
111 * the first connection.
115 /* Flag indicating that the daemon is being started from inetd. */
118 /* Flag indicating that sshd should not detach and become a daemon. */
119 int no_daemon_flag = 0;
121 /* debug goes to stderr unless inetd_flag is set */
124 /* Saved arguments to main(). */
129 * The sockets that the server is listening; this is used in the SIGHUP
132 #define MAX_LISTEN_SOCKS 16
133 int listen_socks[MAX_LISTEN_SOCKS];
134 int num_listen_socks = 0;
137 * the client's version string, passed by sshd2 in compat mode. if != NULL,
138 * sshd will skip the version-number exchange
140 char *client_version_string = NULL;
141 char *server_version_string = NULL;
144 * Any really sensitive data in the application is contained in this
145 * structure. The idea is that this structure could be locked into memory so
146 * that the pages do not get written into swap. However, there are some
147 * problems. The private key contains BIGNUMs, and we do not (in principle)
148 * have access to the internals of them, and locking just the structure is
149 * not very useful. Currently, memory locking is not implemented.
152 Key *server_key; /* empheral server key */
153 Key *ssh1_host_key; /* ssh1 host key */
154 Key **host_keys; /* all private host keys */
157 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
161 * Flag indicating whether the RSA server key needs to be regenerated.
162 * Is set in the SIGALRM handler and cleared when the key is regenerated.
164 int key_do_regen = 0;
166 /* This is set to true when SIGHUP is received. */
167 int received_sighup = 0;
169 /* session identifier, used by RSA-auth */
170 u_char session_id[16];
173 u_char *session_id2 = NULL;
174 int session_id2_len = 0;
176 /* record remote hostname or ip */
177 u_int utmp_len = MAXHOSTNAMELEN;
179 /* Prototypes for various functions defined later in this file. */
180 void do_ssh1_kex(void);
181 void do_ssh2_kex(void);
183 void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *);
184 void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *);
187 * Close all listening sockets
190 close_listen_socks(void)
193 for (i = 0; i < num_listen_socks; i++)
194 close(listen_socks[i]);
195 num_listen_socks = -1;
199 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
200 * the effect is to reread the configuration file (and to regenerate
204 sighup_handler(int sig)
207 signal(SIGHUP, sighup_handler);
211 * Called from the main program after receiving SIGHUP.
212 * Restarts the server.
217 log("Received SIGHUP; restarting.");
218 close_listen_socks();
219 execv(saved_argv[0], saved_argv);
220 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno));
225 * Generic signal handler for terminating signals in the master daemon.
226 * These close the listen socket; not closing it seems to cause "Address
227 * already in use" problems on some machines, which is inconvenient.
230 sigterm_handler(int sig)
232 log("Received signal %d; terminating.", sig);
233 close_listen_socks();
234 unlink(options.pid_file);
239 * SIGCHLD handler. This is called whenever a child dies. This will then
240 * reap any zombies left by exited c.
243 main_sigchld_handler(int sig)
245 int save_errno = errno;
248 while (waitpid(-1, &status, WNOHANG) > 0)
251 signal(SIGCHLD, main_sigchld_handler);
256 * Signal handler for the alarm after the login grace period has expired.
259 grace_alarm_handler(int sig)
261 /* Close the connection. */
264 /* Log error and exit. */
265 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
269 * Signal handler for the key regeneration alarm. Note that this
270 * alarm only occurs in the daemon waiting for connections, and it does not
271 * do anything with the private key or random state before forking.
272 * Thus there should be no concurrency control/asynchronous execution
276 generate_empheral_server_key(void)
281 log("Generating %s%d bit RSA key.", sensitive_data.server_key ? "new " : "",
282 options.server_key_bits);
283 if (sensitive_data.server_key != NULL)
284 key_free(sensitive_data.server_key);
285 sensitive_data.server_key = key_generate(KEY_RSA1, options.server_key_bits);
286 log("RSA key generation complete.");
288 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
291 sensitive_data.ssh1_cookie[i] = rand & 0xff;
298 key_regeneration_alarm(int sig)
300 int save_errno = errno;
301 signal(SIGALRM, SIG_DFL);
307 sshd_exchange_identification(int sock_in, int sock_out)
310 int remote_major, remote_minor;
313 char buf[256]; /* Must not be larger than remote_version. */
314 char remote_version[256]; /* Must be at least as big as buf. */
316 if ((options.protocol & SSH_PROTO_1) &&
317 (options.protocol & SSH_PROTO_2)) {
318 major = PROTOCOL_MAJOR_1;
320 } else if (options.protocol & SSH_PROTO_2) {
321 major = PROTOCOL_MAJOR_2;
322 minor = PROTOCOL_MINOR_2;
324 major = PROTOCOL_MAJOR_1;
325 minor = PROTOCOL_MINOR_1;
327 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
328 server_version_string = xstrdup(buf);
330 if (client_version_string == NULL) {
331 /* Send our protocol version identification. */
332 if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
333 != strlen(server_version_string)) {
334 log("Could not write ident string to %s.", get_remote_ipaddr());
338 /* Read other side's version identification. */
339 memset(buf, 0, sizeof(buf));
340 for (i = 0; i < sizeof(buf) - 1; i++) {
341 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
342 log("Did not receive identification string from %s.",
343 get_remote_ipaddr());
346 if (buf[i] == '\r') {
349 /* Kludge for F-Secure Macintosh < 1.0.2 */
351 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
355 if (buf[i] == '\n') {
361 buf[sizeof(buf) - 1] = 0;
362 client_version_string = xstrdup(buf);
366 * Check that the versions match. In future this might accept
367 * several versions and set appropriate flags to handle them.
369 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
370 &remote_major, &remote_minor, remote_version) != 3) {
371 s = "Protocol mismatch.\n";
372 (void) atomicio(write, sock_out, s, strlen(s));
375 log("Bad protocol version identification '%.100s' from %s",
376 client_version_string, get_remote_ipaddr());
379 debug("Client protocol version %d.%d; client software version %.100s",
380 remote_major, remote_minor, remote_version);
382 compat_datafellows(remote_version);
385 switch(remote_major) {
387 if (remote_minor == 99) {
388 if (options.protocol & SSH_PROTO_2)
394 if (!(options.protocol & SSH_PROTO_1)) {
398 if (remote_minor < 3) {
399 packet_disconnect("Your ssh version is too old and "
400 "is no longer supported. Please install a newer version.");
401 } else if (remote_minor == 3) {
402 /* note that this disables agent-forwarding */
407 if (options.protocol & SSH_PROTO_2) {
416 chop(server_version_string);
417 chop(client_version_string);
418 debug("Local version string %.200s", server_version_string);
421 s = "Protocol major versions differ.\n";
422 (void) atomicio(write, sock_out, s, strlen(s));
425 log("Protocol major versions differ for %s: %.200s vs. %.200s",
427 server_version_string, client_version_string);
431 packet_set_ssh2_format();
435 /* Destroy the host and server keys. They will no longer be needed. */
437 destroy_sensitive_data(void)
441 if (sensitive_data.server_key) {
442 key_free(sensitive_data.server_key);
443 sensitive_data.server_key = NULL;
445 for(i = 0; i < options.num_host_key_files; i++) {
446 if (sensitive_data.host_keys[i]) {
447 key_free(sensitive_data.host_keys[i]);
448 sensitive_data.host_keys[i] = NULL;
451 sensitive_data.ssh1_host_key = NULL;
452 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
455 load_private_key_autodetect(const char *filename)
459 Key *public, *private;
461 if (stat(filename, &st) < 0) {
466 * try to load the public key. right now this only works for RSA1,
467 * since SSH2 keys are fully encrypted
470 public = key_new(type);
471 if (!load_public_key(filename, public, NULL)) {
472 /* ok, so we will assume this is 'some' key */
477 /* Ok, try key with empty passphrase */
478 private = key_new(type);
479 if (load_private_key(filename, "", private, NULL)) {
480 debug("load_private_key_autodetect: type %d %s",
481 private->type, key_type(private));
489 list_hostkey_types(void)
491 static char buf[1024];
494 for(i = 0; i < options.num_host_key_files; i++) {
495 Key *key = sensitive_data.host_keys[i];
501 strlcat(buf, key_ssh_name(key), sizeof buf);
502 strlcat(buf, ",", sizeof buf);
507 if (i > 0 && buf[i-1] == ',')
509 debug("list_hostkey_types: %s", buf);
514 get_hostkey_by_type(int type)
517 for(i = 0; i < options.num_host_key_files; i++) {
518 Key *key = sensitive_data.host_keys[i];
519 if (key != NULL && key->type == type)
526 * returns 1 if connection should be dropped, 0 otherwise.
527 * dropping starts at connection #max_startups_begin with a probability
528 * of (max_startups_rate/100). the probability increases linearly until
529 * all connections are dropped for startups > max_startups
532 drop_connection(int startups)
536 if (startups < options.max_startups_begin)
538 if (startups >= options.max_startups)
540 if (options.max_startups_rate == 100)
543 p = 100 - options.max_startups_rate;
544 p *= startups - options.max_startups_begin;
545 p /= (double) (options.max_startups - options.max_startups_begin);
546 p += options.max_startups_rate;
548 r = arc4random() / (double) UINT_MAX;
550 debug("drop_connection: p %g, r %g", p, r);
551 return (r < p) ? 1 : 0;
554 int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
555 int startup_pipe; /* in child */
558 * Main program for the daemon.
561 main(int ac, char **av)
565 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
569 struct sockaddr_storage from;
570 const char *remote_ip;
573 struct linger linger;
575 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
576 int listen_sock, maxfd;
579 int ret, key_used = 0;
581 __progname = get_progname(av[0]);
588 /* Initialize configuration options to their default values. */
589 initialize_server_options(&options);
591 /* Parse command-line arguments. */
592 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDiqQ46")) != -1) {
601 config_file_name = optarg;
604 if (0 == debug_flag) {
606 options.log_level = SYSLOG_LEVEL_DEBUG1;
607 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
610 fprintf(stderr, "Too high debugging level.\n");
624 options.log_level = SYSLOG_LEVEL_QUIET;
627 options.server_key_bits = atoi(optarg);
630 options.ports_from_cmdline = 1;
631 if (options.num_ports >= MAX_PORTS) {
632 fprintf(stderr, "too many ports.\n");
635 options.ports[options.num_ports++] = atoi(optarg);
638 options.login_grace_time = atoi(optarg);
641 options.key_regeneration_time = atoi(optarg);
644 if (options.num_host_key_files >= MAX_HOSTKEYS) {
645 fprintf(stderr, "too many host keys.\n");
648 options.host_key_files[options.num_host_key_files++] = optarg;
651 client_version_string = optarg;
652 /* only makes sense with inetd_flag, i.e. no listen() */
656 utmp_len = atoi(optarg);
660 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
661 fprintf(stderr, "Usage: %s [options]\n", __progname);
662 fprintf(stderr, "Options:\n");
663 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
664 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
665 fprintf(stderr, " -i Started from inetd\n");
666 fprintf(stderr, " -D Do not fork into daemon mode\n");
667 fprintf(stderr, " -q Quiet (no logging)\n");
668 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
669 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
670 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
671 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
672 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
673 _PATH_HOST_KEY_FILE);
674 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
675 fprintf(stderr, " -4 Use IPv4 only\n");
676 fprintf(stderr, " -6 Use IPv6 only\n");
682 * Force logging to stderr until we have loaded the private host
683 * key (unless started from inetd)
686 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
687 options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
690 /* Read server configuration options from the configuration file. */
691 read_server_config(&options, config_file_name);
693 /* Fill in default values for those options not explicitly set. */
694 fill_default_server_options(&options);
696 /* Check that there are no remaining arguments. */
698 fprintf(stderr, "Extra argument %s.\n", av[optind]);
702 debug("sshd version %.100s", SSH_VERSION);
704 /* load private host keys */
705 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
706 for(i = 0; i < options.num_host_key_files; i++)
707 sensitive_data.host_keys[i] = NULL;
708 sensitive_data.server_key = NULL;
709 sensitive_data.ssh1_host_key = NULL;
710 sensitive_data.have_ssh1_key = 0;
711 sensitive_data.have_ssh2_key = 0;
713 for(i = 0; i < options.num_host_key_files; i++) {
714 Key *key = load_private_key_autodetect(options.host_key_files[i]);
716 error("Could not load host key: %.200s: %.100s",
717 options.host_key_files[i], strerror(errno));
722 sensitive_data.ssh1_host_key = key;
723 sensitive_data.have_ssh1_key = 1;
727 sensitive_data.have_ssh2_key = 1;
730 sensitive_data.host_keys[i] = key;
732 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
733 log("Disabling protocol version 1. Could not load host key");
734 options.protocol &= ~SSH_PROTO_1;
736 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
737 log("Disabling protocol version 2. Could not load host key");
738 options.protocol &= ~SSH_PROTO_2;
740 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
741 log("sshd: no hostkeys available -- exiting.");
745 /* Check certain values for sanity. */
746 if (options.protocol & SSH_PROTO_1) {
747 if (options.server_key_bits < 512 ||
748 options.server_key_bits > 32768) {
749 fprintf(stderr, "Bad server key size.\n");
753 * Check that server and host key lengths differ sufficiently. This
754 * is necessary to make double encryption work with rsaref. Oh, I
755 * hate software patents. I dont know if this can go? Niels
757 if (options.server_key_bits >
758 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
759 options.server_key_bits <
760 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
761 options.server_key_bits =
762 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
763 debug("Forcing server key to %d bits to make it differ from host key.",
764 options.server_key_bits);
768 #ifdef HAVE_SCO_PROTECTED_PW
769 (void) set_auth_parameters(ac, av);
772 /* Initialize the log (it is reinitialized below in case we forked). */
773 if (debug_flag && !inetd_flag)
775 log_init(__progname, options.log_level, options.log_facility, log_stderr);
778 * If not in debugging mode, and not started from inetd, disconnect
779 * from the controlling terminal, and fork. The original process
782 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
785 #endif /* TIOCNOTTY */
786 if (daemon(0, 0) < 0)
787 fatal("daemon() failed: %.200s", strerror(errno));
789 /* Disconnect from the controlling tty. */
791 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
793 (void) ioctl(fd, TIOCNOTTY, NULL);
796 #endif /* TIOCNOTTY */
798 /* Reinitialize the log (because of the fork above). */
799 log_init(__progname, options.log_level, options.log_facility, log_stderr);
801 /* Initialize the random number generator. */
804 /* Chdir to the root directory so that the current disk can be
805 unmounted if desired. */
808 /* Start listening for a socket, unless started from inetd. */
811 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
817 * We intentionally do not close the descriptors 0, 1, and 2
818 * as our code for setting the descriptors won\'t work if
819 * ttyfd happens to be one of those.
821 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
822 if (options.protocol & SSH_PROTO_1)
823 generate_empheral_server_key();
825 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
826 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
828 if (num_listen_socks >= MAX_LISTEN_SOCKS)
829 fatal("Too many listen sockets. "
830 "Enlarge MAX_LISTEN_SOCKS");
831 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
832 ntop, sizeof(ntop), strport, sizeof(strport),
833 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
834 error("getnameinfo failed");
837 /* Create socket for listening. */
838 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
839 if (listen_sock < 0) {
840 /* kernel may not support ipv6 */
841 verbose("socket: %.100s", strerror(errno));
844 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
845 error("listen_sock O_NONBLOCK: %s", strerror(errno));
850 * Set socket options. We try to make the port
851 * reusable and have it close as fast as possible
852 * without waiting in unnecessary wait states on
855 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
856 (void *) &on, sizeof(on));
859 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
860 (void *) &linger, sizeof(linger));
862 debug("Bind to port %s on %s.", strport, ntop);
864 /* Bind the socket to the desired port. */
865 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
867 error("Bind to port %s on %s failed: %.200s.",
868 strport, ntop, strerror(errno));
872 listen_socks[num_listen_socks] = listen_sock;
875 /* Start listening on the port. */
876 log("Server listening on %s port %s.", ntop, strport);
877 if (listen(listen_sock, 5) < 0)
878 fatal("listen: %.100s", strerror(errno));
881 freeaddrinfo(options.listen_addrs);
883 if (!num_listen_socks)
884 fatal("Cannot bind any address.");
888 * Record our pid in /var/run/sshd.pid to make it
889 * easier to kill the correct sshd. We don't want to
890 * do this before the bind above because the bind will
891 * fail if there already is a daemon, and this will
892 * overwrite any old pid in the file.
894 f = fopen(options.pid_file, "wb");
896 fprintf(f, "%u\n", (u_int) getpid());
900 if (options.protocol & SSH_PROTO_1)
901 generate_empheral_server_key();
903 /* Arrange to restart on SIGHUP. The handler needs listen_sock. */
904 signal(SIGHUP, sighup_handler);
906 signal(SIGTERM, sigterm_handler);
907 signal(SIGQUIT, sigterm_handler);
909 /* Arrange SIGCHLD to be caught. */
910 signal(SIGCHLD, main_sigchld_handler);
912 /* setup fd set for listen */
915 for (i = 0; i < num_listen_socks; i++)
916 if (listen_socks[i] > maxfd)
917 maxfd = listen_socks[i];
918 /* pipes connected to unauthenticated childs */
919 startup_pipes = xmalloc(options.max_startups * sizeof(int));
920 for (i = 0; i < options.max_startups; i++)
921 startup_pipes[i] = -1;
924 * Stay listening for connections until the system crashes or
925 * the daemon is killed with a signal.
932 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
933 fdset = (fd_set *)xmalloc(fdsetsz);
934 memset(fdset, 0, fdsetsz);
936 for (i = 0; i < num_listen_socks; i++)
937 FD_SET(listen_socks[i], fdset);
938 for (i = 0; i < options.max_startups; i++)
939 if (startup_pipes[i] != -1)
940 FD_SET(startup_pipes[i], fdset);
942 /* Wait in select until there is a connection. */
943 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
944 if (ret < 0 && errno != EINTR)
945 error("select: %.100s", strerror(errno));
946 if (key_used && key_do_regen) {
947 generate_empheral_server_key();
954 for (i = 0; i < options.max_startups; i++)
955 if (startup_pipes[i] != -1 &&
956 FD_ISSET(startup_pipes[i], fdset)) {
958 * the read end of the pipe is ready
959 * if the child has closed the pipe
960 * after successful authentication
961 * or if the child has died
963 close(startup_pipes[i]);
964 startup_pipes[i] = -1;
967 for (i = 0; i < num_listen_socks; i++) {
968 if (!FD_ISSET(listen_socks[i], fdset))
970 fromlen = sizeof(from);
971 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
974 if (errno != EINTR && errno != EWOULDBLOCK)
975 error("accept: %.100s", strerror(errno));
978 if (fcntl(newsock, F_SETFL, 0) < 0) {
979 error("newsock del O_NONBLOCK: %s", strerror(errno));
982 if (drop_connection(startups) == 1) {
983 debug("drop connection #%d", startups);
987 if (pipe(startup_p) == -1) {
992 for (j = 0; j < options.max_startups; j++)
993 if (startup_pipes[j] == -1) {
994 startup_pipes[j] = startup_p[0];
995 if (maxfd < startup_p[0])
996 maxfd = startup_p[0];
1002 * Got connection. Fork a child to handle it, unless
1003 * we are in debugging mode.
1007 * In debugging mode. Close the listening
1008 * socket, and start processing the
1009 * connection without forking.
1011 debug("Server will not fork when running in debugging mode.");
1012 close_listen_socks();
1020 * Normal production daemon. Fork, and have
1021 * the child process the connection. The
1022 * parent continues listening.
1024 if ((pid = fork()) == 0) {
1026 * Child. Close the listening and max_startup
1027 * sockets. Start using the accepted socket.
1028 * Reinitialize logging (since our pid has
1029 * changed). We break out of the loop to handle
1032 startup_pipe = startup_p[1];
1033 for (j = 0; j < options.max_startups; j++)
1034 if (startup_pipes[j] != -1)
1035 close(startup_pipes[j]);
1036 close_listen_socks();
1039 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1044 /* Parent. Stay in the loop. */
1046 error("fork: %.100s", strerror(errno));
1048 debug("Forked child %d.", pid);
1050 close(startup_p[1]);
1052 /* Mark that the key has been used (it was "given" to the child). */
1053 if ((options.protocol & SSH_PROTO_1) &&
1055 /* Schedule server key regeneration alarm. */
1056 signal(SIGALRM, key_regeneration_alarm);
1057 alarm(options.key_regeneration_time);
1063 /* Close the new socket (the child is now taking care of it). */
1066 /* child process check (or debug mode) */
1067 if (num_listen_socks < 0)
1072 /* This is the child processing a new connection. */
1075 * Disable the key regeneration alarm. We will not regenerate the
1076 * key since we are no longer in a position to give it to anyone. We
1077 * will not restart on SIGHUP since it no longer makes sense.
1080 signal(SIGALRM, SIG_DFL);
1081 signal(SIGHUP, SIG_DFL);
1082 signal(SIGTERM, SIG_DFL);
1083 signal(SIGQUIT, SIG_DFL);
1084 signal(SIGCHLD, SIG_DFL);
1085 signal(SIGINT, SIG_DFL);
1088 * Set socket options for the connection. We want the socket to
1089 * close as fast as possible without waiting for anything. If the
1090 * connection is not a socket, these will do nothing.
1092 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1094 linger.l_linger = 5;
1095 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1097 /* Set keepalives if requested. */
1098 if (options.keepalives &&
1099 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1101 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1104 * Register our connection. This turns encryption off because we do
1107 packet_set_connection(sock_in, sock_out);
1109 remote_port = get_remote_port();
1110 remote_ip = get_remote_ipaddr();
1112 /* Check whether logins are denied from this host. */
1114 /* XXX LIBWRAP noes not know about IPv6 */
1116 struct request_info req;
1118 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, NULL);
1121 if (!hosts_access(&req)) {
1126 /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
1128 #endif /* LIBWRAP */
1129 /* Log the connection. */
1130 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1133 * We don\'t want to listen forever unless the other side
1134 * successfully authenticates itself. So we set up an alarm which is
1135 * cleared after successful authentication. A limit of zero
1136 * indicates no limit. Note that we don\'t set the alarm in debugging
1137 * mode; it is just annoying to have the server exit just when you
1138 * are about to discover the bug.
1140 signal(SIGALRM, grace_alarm_handler);
1142 alarm(options.login_grace_time);
1144 sshd_exchange_identification(sock_in, sock_out);
1146 * Check that the connection comes from a privileged port.
1147 * Rhosts-Authentication only makes sense from priviledged
1148 * programs. Of course, if the intruder has root access on his local
1149 * machine, he can connect from any port. So do not use these
1150 * authentication methods from machines that you do not trust.
1152 if (remote_port >= IPPORT_RESERVED ||
1153 remote_port < IPPORT_RESERVED / 2) {
1154 debug("Rhosts Authentication disabled, "
1155 "originating port not trusted.");
1156 options.rhosts_authentication = 0;
1159 if (!packet_connection_is_ipv4() &&
1160 options.kerberos_authentication) {
1161 debug("Kerberos Authentication disabled, only available for IPv4.");
1162 options.kerberos_authentication = 0;
1166 /* If machine has AFS, set process authentication group. */
1173 packet_set_nonblocking();
1175 /* perform the key exchange */
1176 /* authenticate user and start session */
1179 do_authentication2();
1182 do_authentication();
1186 /* Cleanup user's ticket cache file. */
1187 if (options.kerberos_ticket_cleanup)
1191 /* The connection has been terminated. */
1192 verbose("Closing connection to %.100s", remote_ip);
1196 #endif /* USE_PAM */
1211 BIGNUM *session_key_int;
1212 u_char session_key[SSH_SESSION_KEY_LENGTH];
1214 u_int cipher_type, auth_mask, protocol_flags;
1218 * Generate check bytes that the client must send back in the user
1219 * packet in order for it to be accepted; this is used to defy ip
1220 * spoofing attacks. Note that this only works against somebody
1221 * doing IP spoofing from a remote machine; any machine on the local
1222 * network can still see outgoing packets and catch the random
1223 * cookie. This only affects rhosts authentication, and this is one
1224 * of the reasons why it is inherently insecure.
1226 for (i = 0; i < 8; i++) {
1228 rand = arc4random();
1229 cookie[i] = rand & 0xff;
1234 * Send our public key. We include in the packet 64 bits of random
1235 * data that must be matched in the reply in order to prevent IP
1238 packet_start(SSH_SMSG_PUBLIC_KEY);
1239 for (i = 0; i < 8; i++)
1240 packet_put_char(cookie[i]);
1242 /* Store our public server RSA key. */
1243 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1244 packet_put_bignum(sensitive_data.server_key->rsa->e);
1245 packet_put_bignum(sensitive_data.server_key->rsa->n);
1247 /* Store our public host RSA key. */
1248 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1249 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1250 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1252 /* Put protocol flags. */
1253 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1255 /* Declare which ciphers we support. */
1256 packet_put_int(cipher_mask_ssh1(0));
1258 /* Declare supported authentication types. */
1260 if (options.rhosts_authentication)
1261 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1262 if (options.rhosts_rsa_authentication)
1263 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1264 if (options.rsa_authentication)
1265 auth_mask |= 1 << SSH_AUTH_RSA;
1267 if (options.kerberos_authentication)
1268 auth_mask |= 1 << SSH_AUTH_KERBEROS;
1271 if (options.kerberos_tgt_passing)
1272 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1273 if (options.afs_token_passing)
1274 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1276 if (options.challenge_reponse_authentication == 1)
1277 auth_mask |= 1 << SSH_AUTH_TIS;
1278 if (options.password_authentication)
1279 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1280 packet_put_int(auth_mask);
1282 /* Send the packet and wait for it to be sent. */
1284 packet_write_wait();
1286 debug("Sent %d bit server key and %d bit host key.",
1287 BN_num_bits(sensitive_data.server_key->rsa->n),
1288 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1290 /* Read clients reply (cipher type and session key). */
1291 packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
1293 /* Get cipher type and check whether we accept this. */
1294 cipher_type = packet_get_char();
1296 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1297 packet_disconnect("Warning: client selects unsupported cipher.");
1299 /* Get check bytes from the packet. These must match those we
1300 sent earlier with the public key packet. */
1301 for (i = 0; i < 8; i++)
1302 if (cookie[i] != packet_get_char())
1303 packet_disconnect("IP Spoofing check bytes do not match.");
1305 debug("Encryption type: %.200s", cipher_name(cipher_type));
1307 /* Get the encrypted integer. */
1308 session_key_int = BN_new();
1309 packet_get_bignum(session_key_int, &slen);
1311 protocol_flags = packet_get_int();
1312 packet_set_protocol_flags(protocol_flags);
1314 packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
1317 * Decrypt it using our private server key and private host key (key
1318 * with larger modulus first).
1320 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1321 /* Server key has bigger modulus. */
1322 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1323 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1324 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1325 get_remote_ipaddr(),
1326 BN_num_bits(sensitive_data.server_key->rsa->n),
1327 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1328 SSH_KEY_BITS_RESERVED);
1330 if (rsa_private_decrypt(session_key_int, session_key_int,
1331 sensitive_data.server_key->rsa) <= 0)
1333 if (rsa_private_decrypt(session_key_int, session_key_int,
1334 sensitive_data.ssh1_host_key->rsa) <= 0)
1337 /* Host key has bigger modulus (or they are equal). */
1338 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1339 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1340 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1341 get_remote_ipaddr(),
1342 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1343 BN_num_bits(sensitive_data.server_key->rsa->n),
1344 SSH_KEY_BITS_RESERVED);
1346 if (rsa_private_decrypt(session_key_int, session_key_int,
1347 sensitive_data.ssh1_host_key->rsa) < 0)
1349 if (rsa_private_decrypt(session_key_int, session_key_int,
1350 sensitive_data.server_key->rsa) < 0)
1354 * Extract session key from the decrypted integer. The key is in the
1355 * least significant 256 bits of the integer; the first byte of the
1356 * key is in the highest bits.
1359 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1360 len = BN_num_bytes(session_key_int);
1361 if (len < 0 || len > sizeof(session_key)) {
1362 error("do_connection: bad session key len from %s: "
1363 "session_key_int %d > sizeof(session_key) %lu",
1364 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1367 memset(session_key, 0, sizeof(session_key));
1368 BN_bn2bin(session_key_int,
1369 session_key + sizeof(session_key) - len);
1371 compute_session_id(session_id, cookie,
1372 sensitive_data.ssh1_host_key->rsa->n,
1373 sensitive_data.server_key->rsa->n);
1375 * Xor the first 16 bytes of the session key with the
1378 for (i = 0; i < 16; i++)
1379 session_key[i] ^= session_id[i];
1383 int bytes = BN_num_bytes(session_key_int);
1384 char *buf = xmalloc(bytes);
1387 log("do_connection: generating a fake encryption key");
1388 BN_bn2bin(session_key_int, buf);
1390 MD5_Update(&md, buf, bytes);
1391 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1392 MD5_Final(session_key, &md);
1394 MD5_Update(&md, session_key, 16);
1395 MD5_Update(&md, buf, bytes);
1396 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1397 MD5_Final(session_key + 16, &md);
1398 memset(buf, 0, bytes);
1400 for (i = 0; i < 16; i++)
1401 session_id[i] = session_key[i] ^ session_key[i + 16];
1403 /* Destroy the private and public keys. They will no longer be needed. */
1404 destroy_sensitive_data();
1406 /* Destroy the decrypted integer. It is no longer needed. */
1407 BN_clear_free(session_key_int);
1409 /* Set the session key. From this on all communications will be encrypted. */
1410 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1412 /* Destroy our copy of the session key. It is no longer needed. */
1413 memset(session_key, 0, sizeof(session_key));
1415 debug("Received session key; encryption turned on.");
1417 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1418 packet_start(SSH_SMSG_SUCCESS);
1420 packet_write_wait();
1424 * SSH2 key exchange: diffie-hellman-group1-sha1
1429 Buffer *server_kexinit;
1430 Buffer *client_kexinit;
1434 char *cprop[PROPOSAL_MAX];
1438 if (options.ciphers != NULL) {
1439 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1440 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1442 if (options.macs != NULL) {
1443 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1444 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1446 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1448 server_kexinit = kex_init(myproposal);
1449 client_kexinit = xmalloc(sizeof(*client_kexinit));
1450 buffer_init(client_kexinit);
1452 /* algorithm negotiation */
1453 kex_exchange_kexinit(server_kexinit, client_kexinit, cprop);
1454 kex = kex_choose_conf(cprop, myproposal, 1);
1455 for (i = 0; i < PROPOSAL_MAX; i++)
1458 switch (kex->kex_type) {
1460 ssh_dh1_server(kex, client_kexinit, server_kexinit);
1463 ssh_dhgex_server(kex, client_kexinit, server_kexinit);
1466 fatal("Unsupported key exchange %d", kex->kex_type);
1469 debug("send SSH2_MSG_NEWKEYS.");
1470 packet_start(SSH2_MSG_NEWKEYS);
1472 packet_write_wait();
1473 debug("done: send SSH2_MSG_NEWKEYS.");
1475 debug("Wait SSH2_MSG_NEWKEYS.");
1476 packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1477 debug("GOT SSH2_MSG_NEWKEYS.");
1480 /* send 1st encrypted/maced/compressed message */
1481 packet_start(SSH2_MSG_IGNORE);
1482 packet_put_cstring("markus");
1484 packet_write_wait();
1487 debug("done: KEX2.");
1494 /* diffie-hellman-group1-sha1 */
1497 ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1502 int payload_len, dlen;
1504 u_char *signature = NULL;
1505 u_char *server_host_key_blob = NULL;
1510 BIGNUM *shared_secret = 0;
1512 BIGNUM *dh_client_pub = 0;
1515 hostkey = get_hostkey_by_type(kex->hostkey_type);
1516 if (hostkey == NULL)
1517 fatal("Unsupported hostkey type %d", kex->hostkey_type);
1520 /* generate DH key */
1521 dh = dh_new_group1(); /* XXX depends on 'kex' */
1522 dh_gen_key(dh, kex->we_need * 8);
1524 debug("Wait SSH2_MSG_KEXDH_INIT.");
1525 packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
1528 dh_client_pub = BN_new();
1529 if (dh_client_pub == NULL)
1530 fatal("dh_client_pub == NULL");
1531 packet_get_bignum2(dh_client_pub, &dlen);
1534 fprintf(stderr, "\ndh_client_pub= ");
1535 BN_print_fp(stderr, dh_client_pub);
1536 fprintf(stderr, "\n");
1537 debug("bits %d", BN_num_bits(dh_client_pub));
1541 fprintf(stderr, "\np= ");
1542 BN_print_fp(stderr, dh->p);
1543 fprintf(stderr, "\ng= ");
1545 fprintf(stderr, "\npub= ");
1546 BN_print_fp(stderr, dh->pub_key);
1547 fprintf(stderr, "\n");
1548 DHparams_print_fp(stderr, dh);
1550 if (!dh_pub_is_valid(dh, dh_client_pub))
1551 packet_disconnect("bad client public DH value");
1554 kbuf = xmalloc(klen);
1555 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1558 debug("shared secret: len %d/%d", klen, kout);
1559 fprintf(stderr, "shared secret == ");
1560 for (i = 0; i< kout; i++)
1561 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1562 fprintf(stderr, "\n");
1564 shared_secret = BN_new();
1566 BN_bin2bn(kbuf, kout, shared_secret);
1567 memset(kbuf, 0, klen);
1570 /* XXX precompute? */
1571 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1573 /* calc H */ /* XXX depends on 'kex' */
1575 client_version_string,
1576 server_version_string,
1577 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1578 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1579 (char *)server_host_key_blob, sbloblen,
1584 buffer_free(client_kexinit);
1585 buffer_free(server_kexinit);
1586 xfree(client_kexinit);
1587 xfree(server_kexinit);
1588 BN_free(dh_client_pub);
1590 fprintf(stderr, "hash == ");
1591 for (i = 0; i< 20; i++)
1592 fprintf(stderr, "%02x", (hash[i])&0xff);
1593 fprintf(stderr, "\n");
1595 /* save session id := H */
1596 /* XXX hashlen depends on KEX */
1597 session_id2_len = 20;
1598 session_id2 = xmalloc(session_id2_len);
1599 memcpy(session_id2, hash, session_id2_len);
1602 /* XXX hashlen depends on KEX */
1603 key_sign(hostkey, &signature, &slen, hash, 20);
1605 destroy_sensitive_data();
1607 /* send server hostkey, DH pubkey 'f' and singed H */
1608 packet_start(SSH2_MSG_KEXDH_REPLY);
1609 packet_put_string((char *)server_host_key_blob, sbloblen);
1610 packet_put_bignum2(dh->pub_key); /* f */
1611 packet_put_string((char *)signature, slen);
1614 xfree(server_host_key_blob);
1615 packet_write_wait();
1617 kex_derive_keys(kex, hash, shared_secret);
1618 BN_clear_free(shared_secret);
1619 packet_set_kex(kex);
1621 /* have keys, free DH */
1625 /* diffie-hellman-group-exchange-sha1 */
1628 ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1633 int payload_len, dlen;
1635 u_char *signature = NULL;
1636 u_char *server_host_key_blob = NULL;
1641 BIGNUM *shared_secret = 0;
1643 BIGNUM *dh_client_pub = 0;
1646 hostkey = get_hostkey_by_type(kex->hostkey_type);
1647 if (hostkey == NULL)
1648 fatal("Unsupported hostkey type %d", kex->hostkey_type);
1651 debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST.");
1652 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST);
1653 nbits = packet_get_int();
1654 dh = choose_dh(nbits);
1656 debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP.");
1657 packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
1658 packet_put_bignum2(dh->p);
1659 packet_put_bignum2(dh->g);
1661 packet_write_wait();
1663 /* Compute our exchange value in parallel with the client */
1665 dh_gen_key(dh, kex->we_need * 8);
1667 debug("Wait SSH2_MSG_KEX_DH_GEX_INIT.");
1668 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT);
1671 dh_client_pub = BN_new();
1672 if (dh_client_pub == NULL)
1673 fatal("dh_client_pub == NULL");
1674 packet_get_bignum2(dh_client_pub, &dlen);
1677 fprintf(stderr, "\ndh_client_pub= ");
1678 BN_print_fp(stderr, dh_client_pub);
1679 fprintf(stderr, "\n");
1680 debug("bits %d", BN_num_bits(dh_client_pub));
1684 fprintf(stderr, "\np= ");
1685 BN_print_fp(stderr, dh->p);
1686 fprintf(stderr, "\ng= ");
1688 fprintf(stderr, "\npub= ");
1689 BN_print_fp(stderr, dh->pub_key);
1690 fprintf(stderr, "\n");
1691 DHparams_print_fp(stderr, dh);
1693 if (!dh_pub_is_valid(dh, dh_client_pub))
1694 packet_disconnect("bad client public DH value");
1697 kbuf = xmalloc(klen);
1698 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1701 debug("shared secret: len %d/%d", klen, kout);
1702 fprintf(stderr, "shared secret == ");
1703 for (i = 0; i< kout; i++)
1704 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1705 fprintf(stderr, "\n");
1707 shared_secret = BN_new();
1709 BN_bin2bn(kbuf, kout, shared_secret);
1710 memset(kbuf, 0, klen);
1713 /* XXX precompute? */
1714 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1716 /* calc H */ /* XXX depends on 'kex' */
1717 hash = kex_hash_gex(
1718 client_version_string,
1719 server_version_string,
1720 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1721 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1722 (char *)server_host_key_blob, sbloblen,
1723 nbits, dh->p, dh->g,
1728 buffer_free(client_kexinit);
1729 buffer_free(server_kexinit);
1730 xfree(client_kexinit);
1731 xfree(server_kexinit);
1732 BN_free(dh_client_pub);
1734 fprintf(stderr, "hash == ");
1735 for (i = 0; i< 20; i++)
1736 fprintf(stderr, "%02x", (hash[i])&0xff);
1737 fprintf(stderr, "\n");
1739 /* save session id := H */
1740 /* XXX hashlen depends on KEX */
1741 session_id2_len = 20;
1742 session_id2 = xmalloc(session_id2_len);
1743 memcpy(session_id2, hash, session_id2_len);
1746 /* XXX hashlen depends on KEX */
1747 key_sign(hostkey, &signature, &slen, hash, 20);
1749 destroy_sensitive_data();
1751 /* send server hostkey, DH pubkey 'f' and singed H */
1752 packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
1753 packet_put_string((char *)server_host_key_blob, sbloblen);
1754 packet_put_bignum2(dh->pub_key); /* f */
1755 packet_put_string((char *)signature, slen);
1758 xfree(server_host_key_blob);
1759 packet_write_wait();
1761 kex_derive_keys(kex, hash, shared_secret);
1762 BN_clear_free(shared_secret);
1763 packet_set_kex(kex);
1765 /* have keys, free DH */