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 1.174 2001/03/09 12:30:29 deraadt 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; /* ephemeral 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_ephemeral_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,
692 /* Read server configuration options from the configuration file. */
693 read_server_config(&options, config_file_name);
695 /* Fill in default values for those options not explicitly set. */
696 fill_default_server_options(&options);
698 /* Check that there are no remaining arguments. */
700 fprintf(stderr, "Extra argument %s.\n", av[optind]);
704 debug("sshd version %.100s", SSH_VERSION);
706 /* load private host keys */
707 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
708 for(i = 0; i < options.num_host_key_files; i++)
709 sensitive_data.host_keys[i] = NULL;
710 sensitive_data.server_key = NULL;
711 sensitive_data.ssh1_host_key = NULL;
712 sensitive_data.have_ssh1_key = 0;
713 sensitive_data.have_ssh2_key = 0;
715 for(i = 0; i < options.num_host_key_files; i++) {
716 Key *key = load_private_key_autodetect(options.host_key_files[i]);
718 error("Could not load host key: %.200s: %.100s",
719 options.host_key_files[i], strerror(errno));
724 sensitive_data.ssh1_host_key = key;
725 sensitive_data.have_ssh1_key = 1;
729 sensitive_data.have_ssh2_key = 1;
732 sensitive_data.host_keys[i] = key;
734 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
735 log("Disabling protocol version 1. Could not load host key");
736 options.protocol &= ~SSH_PROTO_1;
738 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
739 log("Disabling protocol version 2. Could not load host key");
740 options.protocol &= ~SSH_PROTO_2;
742 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
743 log("sshd: no hostkeys available -- exiting.");
747 /* Check certain values for sanity. */
748 if (options.protocol & SSH_PROTO_1) {
749 if (options.server_key_bits < 512 ||
750 options.server_key_bits > 32768) {
751 fprintf(stderr, "Bad server key size.\n");
755 * Check that server and host key lengths differ sufficiently. This
756 * is necessary to make double encryption work with rsaref. Oh, I
757 * hate software patents. I dont know if this can go? Niels
759 if (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 options.server_key_bits =
764 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
765 debug("Forcing server key to %d bits to make it differ from host key.",
766 options.server_key_bits);
770 #ifdef HAVE_SCO_PROTECTED_PW
771 (void) set_auth_parameters(ac, av);
774 /* Initialize the log (it is reinitialized below in case we forked). */
775 if (debug_flag && !inetd_flag)
777 log_init(__progname, options.log_level, options.log_facility, log_stderr);
780 * If not in debugging mode, and not started from inetd, disconnect
781 * from the controlling terminal, and fork. The original process
784 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
787 #endif /* TIOCNOTTY */
788 if (daemon(0, 0) < 0)
789 fatal("daemon() failed: %.200s", strerror(errno));
791 /* Disconnect from the controlling tty. */
793 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
795 (void) ioctl(fd, TIOCNOTTY, NULL);
798 #endif /* TIOCNOTTY */
800 /* Reinitialize the log (because of the fork above). */
801 log_init(__progname, options.log_level, options.log_facility, log_stderr);
803 /* Initialize the random number generator. */
806 /* Chdir to the root directory so that the current disk can be
807 unmounted if desired. */
810 /* Start listening for a socket, unless started from inetd. */
813 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
819 * We intentionally do not close the descriptors 0, 1, and 2
820 * as our code for setting the descriptors won\'t work if
821 * ttyfd happens to be one of those.
823 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
824 if (options.protocol & SSH_PROTO_1)
825 generate_ephemeral_server_key();
827 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
828 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
830 if (num_listen_socks >= MAX_LISTEN_SOCKS)
831 fatal("Too many listen sockets. "
832 "Enlarge MAX_LISTEN_SOCKS");
833 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
834 ntop, sizeof(ntop), strport, sizeof(strport),
835 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
836 error("getnameinfo failed");
839 /* Create socket for listening. */
840 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
841 if (listen_sock < 0) {
842 /* kernel may not support ipv6 */
843 verbose("socket: %.100s", strerror(errno));
846 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
847 error("listen_sock O_NONBLOCK: %s", strerror(errno));
852 * Set socket options. We try to make the port
853 * reusable and have it close as fast as possible
854 * without waiting in unnecessary wait states on
857 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
858 (void *) &on, sizeof(on));
861 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
862 (void *) &linger, sizeof(linger));
864 debug("Bind to port %s on %s.", strport, ntop);
866 /* Bind the socket to the desired port. */
867 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
869 error("Bind to port %s on %s failed: %.200s.",
870 strport, ntop, strerror(errno));
874 listen_socks[num_listen_socks] = listen_sock;
877 /* Start listening on the port. */
878 log("Server listening on %s port %s.", ntop, strport);
879 if (listen(listen_sock, 5) < 0)
880 fatal("listen: %.100s", strerror(errno));
883 freeaddrinfo(options.listen_addrs);
885 if (!num_listen_socks)
886 fatal("Cannot bind any address.");
890 * Record our pid in /var/run/sshd.pid to make it
891 * easier to kill the correct sshd. We don't want to
892 * do this before the bind above because the bind will
893 * fail if there already is a daemon, and this will
894 * overwrite any old pid in the file.
896 f = fopen(options.pid_file, "wb");
898 fprintf(f, "%u\n", (u_int) getpid());
902 if (options.protocol & SSH_PROTO_1)
903 generate_ephemeral_server_key();
905 /* Arrange to restart on SIGHUP. The handler needs listen_sock. */
906 signal(SIGHUP, sighup_handler);
908 signal(SIGTERM, sigterm_handler);
909 signal(SIGQUIT, sigterm_handler);
911 /* Arrange SIGCHLD to be caught. */
912 signal(SIGCHLD, main_sigchld_handler);
914 /* setup fd set for listen */
917 for (i = 0; i < num_listen_socks; i++)
918 if (listen_socks[i] > maxfd)
919 maxfd = listen_socks[i];
920 /* pipes connected to unauthenticated childs */
921 startup_pipes = xmalloc(options.max_startups * sizeof(int));
922 for (i = 0; i < options.max_startups; i++)
923 startup_pipes[i] = -1;
926 * Stay listening for connections until the system crashes or
927 * the daemon is killed with a signal.
934 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
935 fdset = (fd_set *)xmalloc(fdsetsz);
936 memset(fdset, 0, fdsetsz);
938 for (i = 0; i < num_listen_socks; i++)
939 FD_SET(listen_socks[i], fdset);
940 for (i = 0; i < options.max_startups; i++)
941 if (startup_pipes[i] != -1)
942 FD_SET(startup_pipes[i], fdset);
944 /* Wait in select until there is a connection. */
945 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
946 if (ret < 0 && errno != EINTR)
947 error("select: %.100s", strerror(errno));
948 if (key_used && key_do_regen) {
949 generate_ephemeral_server_key();
956 for (i = 0; i < options.max_startups; i++)
957 if (startup_pipes[i] != -1 &&
958 FD_ISSET(startup_pipes[i], fdset)) {
960 * the read end of the pipe is ready
961 * if the child has closed the pipe
962 * after successful authentication
963 * or if the child has died
965 close(startup_pipes[i]);
966 startup_pipes[i] = -1;
969 for (i = 0; i < num_listen_socks; i++) {
970 if (!FD_ISSET(listen_socks[i], fdset))
972 fromlen = sizeof(from);
973 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
976 if (errno != EINTR && errno != EWOULDBLOCK)
977 error("accept: %.100s", strerror(errno));
980 if (fcntl(newsock, F_SETFL, 0) < 0) {
981 error("newsock del O_NONBLOCK: %s", strerror(errno));
984 if (drop_connection(startups) == 1) {
985 debug("drop connection #%d", startups);
989 if (pipe(startup_p) == -1) {
994 for (j = 0; j < options.max_startups; j++)
995 if (startup_pipes[j] == -1) {
996 startup_pipes[j] = startup_p[0];
997 if (maxfd < startup_p[0])
998 maxfd = startup_p[0];
1004 * Got connection. Fork a child to handle it, unless
1005 * we are in debugging mode.
1009 * In debugging mode. Close the listening
1010 * socket, and start processing the
1011 * connection without forking.
1013 debug("Server will not fork when running in debugging mode.");
1014 close_listen_socks();
1022 * Normal production daemon. Fork, and have
1023 * the child process the connection. The
1024 * parent continues listening.
1026 if ((pid = fork()) == 0) {
1028 * Child. Close the listening and max_startup
1029 * sockets. Start using the accepted socket.
1030 * Reinitialize logging (since our pid has
1031 * changed). We break out of the loop to handle
1034 startup_pipe = startup_p[1];
1035 for (j = 0; j < options.max_startups; j++)
1036 if (startup_pipes[j] != -1)
1037 close(startup_pipes[j]);
1038 close_listen_socks();
1041 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1046 /* Parent. Stay in the loop. */
1048 error("fork: %.100s", strerror(errno));
1050 debug("Forked child %d.", pid);
1052 close(startup_p[1]);
1054 /* Mark that the key has been used (it was "given" to the child). */
1055 if ((options.protocol & SSH_PROTO_1) &&
1057 /* Schedule server key regeneration alarm. */
1058 signal(SIGALRM, key_regeneration_alarm);
1059 alarm(options.key_regeneration_time);
1065 /* Close the new socket (the child is now taking care of it). */
1068 /* child process check (or debug mode) */
1069 if (num_listen_socks < 0)
1074 /* This is the child processing a new connection. */
1077 * Disable the key regeneration alarm. We will not regenerate the
1078 * key since we are no longer in a position to give it to anyone. We
1079 * will not restart on SIGHUP since it no longer makes sense.
1082 signal(SIGALRM, SIG_DFL);
1083 signal(SIGHUP, SIG_DFL);
1084 signal(SIGTERM, SIG_DFL);
1085 signal(SIGQUIT, SIG_DFL);
1086 signal(SIGCHLD, SIG_DFL);
1087 signal(SIGINT, SIG_DFL);
1090 * Set socket options for the connection. We want the socket to
1091 * close as fast as possible without waiting for anything. If the
1092 * connection is not a socket, these will do nothing.
1094 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1096 linger.l_linger = 5;
1097 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1099 /* Set keepalives if requested. */
1100 if (options.keepalives &&
1101 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1103 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1106 * Register our connection. This turns encryption off because we do
1109 packet_set_connection(sock_in, sock_out);
1111 remote_port = get_remote_port();
1112 remote_ip = get_remote_ipaddr();
1114 /* Check whether logins are denied from this host. */
1116 /* XXX LIBWRAP noes not know about IPv6 */
1118 struct request_info req;
1120 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, NULL);
1123 if (!hosts_access(&req)) {
1128 /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
1130 #endif /* LIBWRAP */
1131 /* Log the connection. */
1132 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1135 * We don\'t want to listen forever unless the other side
1136 * successfully authenticates itself. So we set up an alarm which is
1137 * cleared after successful authentication. A limit of zero
1138 * indicates no limit. Note that we don\'t set the alarm in debugging
1139 * mode; it is just annoying to have the server exit just when you
1140 * are about to discover the bug.
1142 signal(SIGALRM, grace_alarm_handler);
1144 alarm(options.login_grace_time);
1146 sshd_exchange_identification(sock_in, sock_out);
1148 * Check that the connection comes from a privileged port.
1149 * Rhosts-Authentication only makes sense from priviledged
1150 * programs. Of course, if the intruder has root access on his local
1151 * machine, he can connect from any port. So do not use these
1152 * authentication methods from machines that you do not trust.
1154 if (remote_port >= IPPORT_RESERVED ||
1155 remote_port < IPPORT_RESERVED / 2) {
1156 debug("Rhosts Authentication disabled, "
1157 "originating port not trusted.");
1158 options.rhosts_authentication = 0;
1161 if (!packet_connection_is_ipv4() &&
1162 options.kerberos_authentication) {
1163 debug("Kerberos Authentication disabled, only available for IPv4.");
1164 options.kerberos_authentication = 0;
1168 /* If machine has AFS, set process authentication group. */
1175 packet_set_nonblocking();
1177 /* perform the key exchange */
1178 /* authenticate user and start session */
1181 do_authentication2();
1184 do_authentication();
1188 /* Cleanup user's ticket cache file. */
1189 if (options.kerberos_ticket_cleanup)
1193 /* The connection has been terminated. */
1194 verbose("Closing connection to %.100s", remote_ip);
1198 #endif /* USE_PAM */
1213 BIGNUM *session_key_int;
1214 u_char session_key[SSH_SESSION_KEY_LENGTH];
1216 u_int cipher_type, auth_mask, protocol_flags;
1220 * Generate check bytes that the client must send back in the user
1221 * packet in order for it to be accepted; this is used to defy ip
1222 * spoofing attacks. Note that this only works against somebody
1223 * doing IP spoofing from a remote machine; any machine on the local
1224 * network can still see outgoing packets and catch the random
1225 * cookie. This only affects rhosts authentication, and this is one
1226 * of the reasons why it is inherently insecure.
1228 for (i = 0; i < 8; i++) {
1230 rand = arc4random();
1231 cookie[i] = rand & 0xff;
1236 * Send our public key. We include in the packet 64 bits of random
1237 * data that must be matched in the reply in order to prevent IP
1240 packet_start(SSH_SMSG_PUBLIC_KEY);
1241 for (i = 0; i < 8; i++)
1242 packet_put_char(cookie[i]);
1244 /* Store our public server RSA key. */
1245 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1246 packet_put_bignum(sensitive_data.server_key->rsa->e);
1247 packet_put_bignum(sensitive_data.server_key->rsa->n);
1249 /* Store our public host RSA key. */
1250 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1251 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1252 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1254 /* Put protocol flags. */
1255 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1257 /* Declare which ciphers we support. */
1258 packet_put_int(cipher_mask_ssh1(0));
1260 /* Declare supported authentication types. */
1262 if (options.rhosts_authentication)
1263 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1264 if (options.rhosts_rsa_authentication)
1265 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1266 if (options.rsa_authentication)
1267 auth_mask |= 1 << SSH_AUTH_RSA;
1269 if (options.kerberos_authentication)
1270 auth_mask |= 1 << SSH_AUTH_KERBEROS;
1273 if (options.kerberos_tgt_passing)
1274 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1275 if (options.afs_token_passing)
1276 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1278 if (options.challenge_reponse_authentication == 1)
1279 auth_mask |= 1 << SSH_AUTH_TIS;
1280 if (options.password_authentication)
1281 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1282 packet_put_int(auth_mask);
1284 /* Send the packet and wait for it to be sent. */
1286 packet_write_wait();
1288 debug("Sent %d bit server key and %d bit host key.",
1289 BN_num_bits(sensitive_data.server_key->rsa->n),
1290 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1292 /* Read clients reply (cipher type and session key). */
1293 packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
1295 /* Get cipher type and check whether we accept this. */
1296 cipher_type = packet_get_char();
1298 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1299 packet_disconnect("Warning: client selects unsupported cipher.");
1301 /* Get check bytes from the packet. These must match those we
1302 sent earlier with the public key packet. */
1303 for (i = 0; i < 8; i++)
1304 if (cookie[i] != packet_get_char())
1305 packet_disconnect("IP Spoofing check bytes do not match.");
1307 debug("Encryption type: %.200s", cipher_name(cipher_type));
1309 /* Get the encrypted integer. */
1310 session_key_int = BN_new();
1311 packet_get_bignum(session_key_int, &slen);
1313 protocol_flags = packet_get_int();
1314 packet_set_protocol_flags(protocol_flags);
1316 packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
1319 * Decrypt it using our private server key and private host key (key
1320 * with larger modulus first).
1322 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1323 /* Server key has bigger modulus. */
1324 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1325 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1326 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1327 get_remote_ipaddr(),
1328 BN_num_bits(sensitive_data.server_key->rsa->n),
1329 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1330 SSH_KEY_BITS_RESERVED);
1332 if (rsa_private_decrypt(session_key_int, session_key_int,
1333 sensitive_data.server_key->rsa) <= 0)
1335 if (rsa_private_decrypt(session_key_int, session_key_int,
1336 sensitive_data.ssh1_host_key->rsa) <= 0)
1339 /* Host key has bigger modulus (or they are equal). */
1340 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1341 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1342 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1343 get_remote_ipaddr(),
1344 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1345 BN_num_bits(sensitive_data.server_key->rsa->n),
1346 SSH_KEY_BITS_RESERVED);
1348 if (rsa_private_decrypt(session_key_int, session_key_int,
1349 sensitive_data.ssh1_host_key->rsa) < 0)
1351 if (rsa_private_decrypt(session_key_int, session_key_int,
1352 sensitive_data.server_key->rsa) < 0)
1356 * Extract session key from the decrypted integer. The key is in the
1357 * least significant 256 bits of the integer; the first byte of the
1358 * key is in the highest bits.
1361 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1362 len = BN_num_bytes(session_key_int);
1363 if (len < 0 || len > sizeof(session_key)) {
1364 error("do_connection: bad session key len from %s: "
1365 "session_key_int %d > sizeof(session_key) %lu",
1366 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1369 memset(session_key, 0, sizeof(session_key));
1370 BN_bn2bin(session_key_int,
1371 session_key + sizeof(session_key) - len);
1373 compute_session_id(session_id, cookie,
1374 sensitive_data.ssh1_host_key->rsa->n,
1375 sensitive_data.server_key->rsa->n);
1377 * Xor the first 16 bytes of the session key with the
1380 for (i = 0; i < 16; i++)
1381 session_key[i] ^= session_id[i];
1385 int bytes = BN_num_bytes(session_key_int);
1386 char *buf = xmalloc(bytes);
1389 log("do_connection: generating a fake encryption key");
1390 BN_bn2bin(session_key_int, buf);
1392 MD5_Update(&md, buf, bytes);
1393 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1394 MD5_Final(session_key, &md);
1396 MD5_Update(&md, session_key, 16);
1397 MD5_Update(&md, buf, bytes);
1398 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1399 MD5_Final(session_key + 16, &md);
1400 memset(buf, 0, bytes);
1402 for (i = 0; i < 16; i++)
1403 session_id[i] = session_key[i] ^ session_key[i + 16];
1405 /* Destroy the private and public keys. They will no longer be needed. */
1406 destroy_sensitive_data();
1408 /* Destroy the decrypted integer. It is no longer needed. */
1409 BN_clear_free(session_key_int);
1411 /* Set the session key. From this on all communications will be encrypted. */
1412 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1414 /* Destroy our copy of the session key. It is no longer needed. */
1415 memset(session_key, 0, sizeof(session_key));
1417 debug("Received session key; encryption turned on.");
1419 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1420 packet_start(SSH_SMSG_SUCCESS);
1422 packet_write_wait();
1426 * SSH2 key exchange: diffie-hellman-group1-sha1
1431 Buffer *server_kexinit;
1432 Buffer *client_kexinit;
1436 char *cprop[PROPOSAL_MAX];
1440 if (options.ciphers != NULL) {
1441 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1442 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1444 if (options.macs != NULL) {
1445 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1446 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1448 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1450 server_kexinit = kex_init(myproposal);
1451 client_kexinit = xmalloc(sizeof(*client_kexinit));
1452 buffer_init(client_kexinit);
1454 /* algorithm negotiation */
1455 kex_exchange_kexinit(server_kexinit, client_kexinit, cprop);
1456 kex = kex_choose_conf(cprop, myproposal, 1);
1457 for (i = 0; i < PROPOSAL_MAX; i++)
1460 switch (kex->kex_type) {
1462 ssh_dh1_server(kex, client_kexinit, server_kexinit);
1465 ssh_dhgex_server(kex, client_kexinit, server_kexinit);
1468 fatal("Unsupported key exchange %d", kex->kex_type);
1471 debug("send SSH2_MSG_NEWKEYS.");
1472 packet_start(SSH2_MSG_NEWKEYS);
1474 packet_write_wait();
1475 debug("done: send SSH2_MSG_NEWKEYS.");
1477 debug("Wait SSH2_MSG_NEWKEYS.");
1478 packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1479 debug("GOT SSH2_MSG_NEWKEYS.");
1482 /* send 1st encrypted/maced/compressed message */
1483 packet_start(SSH2_MSG_IGNORE);
1484 packet_put_cstring("markus");
1486 packet_write_wait();
1489 debug("done: KEX2.");
1496 /* diffie-hellman-group1-sha1 */
1499 ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1504 int payload_len, dlen;
1506 u_char *signature = NULL;
1507 u_char *server_host_key_blob = NULL;
1512 BIGNUM *shared_secret = 0;
1514 BIGNUM *dh_client_pub = 0;
1517 hostkey = get_hostkey_by_type(kex->hostkey_type);
1518 if (hostkey == NULL)
1519 fatal("Unsupported hostkey type %d", kex->hostkey_type);
1522 /* generate DH key */
1523 dh = dh_new_group1(); /* XXX depends on 'kex' */
1524 dh_gen_key(dh, kex->we_need * 8);
1526 debug("Wait SSH2_MSG_KEXDH_INIT.");
1527 packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
1530 dh_client_pub = BN_new();
1531 if (dh_client_pub == NULL)
1532 fatal("dh_client_pub == NULL");
1533 packet_get_bignum2(dh_client_pub, &dlen);
1536 fprintf(stderr, "\ndh_client_pub= ");
1537 BN_print_fp(stderr, dh_client_pub);
1538 fprintf(stderr, "\n");
1539 debug("bits %d", BN_num_bits(dh_client_pub));
1543 fprintf(stderr, "\np= ");
1544 BN_print_fp(stderr, dh->p);
1545 fprintf(stderr, "\ng= ");
1547 fprintf(stderr, "\npub= ");
1548 BN_print_fp(stderr, dh->pub_key);
1549 fprintf(stderr, "\n");
1550 DHparams_print_fp(stderr, dh);
1552 if (!dh_pub_is_valid(dh, dh_client_pub))
1553 packet_disconnect("bad client public DH value");
1556 kbuf = xmalloc(klen);
1557 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1560 debug("shared secret: len %d/%d", klen, kout);
1561 fprintf(stderr, "shared secret == ");
1562 for (i = 0; i< kout; i++)
1563 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1564 fprintf(stderr, "\n");
1566 shared_secret = BN_new();
1568 BN_bin2bn(kbuf, kout, shared_secret);
1569 memset(kbuf, 0, klen);
1572 /* XXX precompute? */
1573 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1575 /* calc H */ /* XXX depends on 'kex' */
1577 client_version_string,
1578 server_version_string,
1579 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1580 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1581 (char *)server_host_key_blob, sbloblen,
1586 buffer_free(client_kexinit);
1587 buffer_free(server_kexinit);
1588 xfree(client_kexinit);
1589 xfree(server_kexinit);
1590 BN_free(dh_client_pub);
1592 fprintf(stderr, "hash == ");
1593 for (i = 0; i< 20; i++)
1594 fprintf(stderr, "%02x", (hash[i])&0xff);
1595 fprintf(stderr, "\n");
1597 /* save session id := H */
1598 /* XXX hashlen depends on KEX */
1599 session_id2_len = 20;
1600 session_id2 = xmalloc(session_id2_len);
1601 memcpy(session_id2, hash, session_id2_len);
1604 /* XXX hashlen depends on KEX */
1605 key_sign(hostkey, &signature, &slen, hash, 20);
1607 destroy_sensitive_data();
1609 /* send server hostkey, DH pubkey 'f' and singed H */
1610 packet_start(SSH2_MSG_KEXDH_REPLY);
1611 packet_put_string((char *)server_host_key_blob, sbloblen);
1612 packet_put_bignum2(dh->pub_key); /* f */
1613 packet_put_string((char *)signature, slen);
1616 xfree(server_host_key_blob);
1617 packet_write_wait();
1619 kex_derive_keys(kex, hash, shared_secret);
1620 BN_clear_free(shared_secret);
1621 packet_set_kex(kex);
1623 /* have keys, free DH */
1627 /* diffie-hellman-group-exchange-sha1 */
1630 ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1635 int payload_len, dlen;
1637 u_char *signature = NULL;
1638 u_char *server_host_key_blob = NULL;
1643 BIGNUM *shared_secret = 0;
1645 BIGNUM *dh_client_pub = 0;
1648 hostkey = get_hostkey_by_type(kex->hostkey_type);
1649 if (hostkey == NULL)
1650 fatal("Unsupported hostkey type %d", kex->hostkey_type);
1653 debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST.");
1654 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST);
1655 nbits = packet_get_int();
1656 dh = choose_dh(nbits);
1658 debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP.");
1659 packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
1660 packet_put_bignum2(dh->p);
1661 packet_put_bignum2(dh->g);
1663 packet_write_wait();
1665 /* Compute our exchange value in parallel with the client */
1667 dh_gen_key(dh, kex->we_need * 8);
1669 debug("Wait SSH2_MSG_KEX_DH_GEX_INIT.");
1670 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT);
1673 dh_client_pub = BN_new();
1674 if (dh_client_pub == NULL)
1675 fatal("dh_client_pub == NULL");
1676 packet_get_bignum2(dh_client_pub, &dlen);
1679 fprintf(stderr, "\ndh_client_pub= ");
1680 BN_print_fp(stderr, dh_client_pub);
1681 fprintf(stderr, "\n");
1682 debug("bits %d", BN_num_bits(dh_client_pub));
1686 fprintf(stderr, "\np= ");
1687 BN_print_fp(stderr, dh->p);
1688 fprintf(stderr, "\ng= ");
1690 fprintf(stderr, "\npub= ");
1691 BN_print_fp(stderr, dh->pub_key);
1692 fprintf(stderr, "\n");
1693 DHparams_print_fp(stderr, dh);
1695 if (!dh_pub_is_valid(dh, dh_client_pub))
1696 packet_disconnect("bad client public DH value");
1699 kbuf = xmalloc(klen);
1700 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1703 debug("shared secret: len %d/%d", klen, kout);
1704 fprintf(stderr, "shared secret == ");
1705 for (i = 0; i< kout; i++)
1706 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1707 fprintf(stderr, "\n");
1709 shared_secret = BN_new();
1711 BN_bin2bn(kbuf, kout, shared_secret);
1712 memset(kbuf, 0, klen);
1715 /* XXX precompute? */
1716 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1718 /* calc H */ /* XXX depends on 'kex' */
1719 hash = kex_hash_gex(
1720 client_version_string,
1721 server_version_string,
1722 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1723 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1724 (char *)server_host_key_blob, sbloblen,
1725 nbits, dh->p, dh->g,
1730 buffer_free(client_kexinit);
1731 buffer_free(server_kexinit);
1732 xfree(client_kexinit);
1733 xfree(server_kexinit);
1734 BN_free(dh_client_pub);
1736 fprintf(stderr, "hash == ");
1737 for (i = 0; i< 20; i++)
1738 fprintf(stderr, "%02x", (hash[i])&0xff);
1739 fprintf(stderr, "\n");
1741 /* save session id := H */
1742 /* XXX hashlen depends on KEX */
1743 session_id2_len = 20;
1744 session_id2 = xmalloc(session_id2_len);
1745 memcpy(session_id2, hash, session_id2_len);
1748 /* XXX hashlen depends on KEX */
1749 key_sign(hostkey, &signature, &slen, hash, 20);
1751 destroy_sensitive_data();
1753 /* send server hostkey, DH pubkey 'f' and singed H */
1754 packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
1755 packet_put_string((char *)server_host_key_blob, sbloblen);
1756 packet_put_bignum2(dh->pub_key); /* f */
1757 packet_put_string((char *)signature, slen);
1760 xfree(server_host_key_blob);
1761 packet_write_wait();
1763 kex_derive_keys(kex, hash, shared_secret);
1764 BN_clear_free(shared_secret);
1765 packet_set_kex(kex);
1767 /* have keys, free DH */