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 1.185 2001/03/29 23:42:01 djm 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 verbose("Generating %s%d bit RSA key.",
282 sensitive_data.server_key ? "new " : "", 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,
286 options.server_key_bits);
287 verbose("RSA key generation complete.");
289 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
292 sensitive_data.ssh1_cookie[i] = rand & 0xff;
299 key_regeneration_alarm(int sig)
301 int save_errno = errno;
302 signal(SIGALRM, SIG_DFL);
308 sshd_exchange_identification(int sock_in, int sock_out)
311 int remote_major, remote_minor;
314 char buf[256]; /* Must not be larger than remote_version. */
315 char remote_version[256]; /* Must be at least as big as buf. */
317 if ((options.protocol & SSH_PROTO_1) &&
318 (options.protocol & SSH_PROTO_2)) {
319 major = PROTOCOL_MAJOR_1;
321 } else if (options.protocol & SSH_PROTO_2) {
322 major = PROTOCOL_MAJOR_2;
323 minor = PROTOCOL_MINOR_2;
325 major = PROTOCOL_MAJOR_1;
326 minor = PROTOCOL_MINOR_1;
328 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
329 server_version_string = xstrdup(buf);
331 if (client_version_string == NULL) {
332 /* Send our protocol version identification. */
333 if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
334 != strlen(server_version_string)) {
335 log("Could not write ident string to %s.", get_remote_ipaddr());
339 /* Read other side's version identification. */
340 memset(buf, 0, sizeof(buf));
341 for (i = 0; i < sizeof(buf) - 1; i++) {
342 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
343 log("Did not receive identification string from %s.",
344 get_remote_ipaddr());
347 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') {
360 buf[sizeof(buf) - 1] = 0;
361 client_version_string = xstrdup(buf);
365 * Check that the versions match. In future this might accept
366 * several versions and set appropriate flags to handle them.
368 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
369 &remote_major, &remote_minor, remote_version) != 3) {
370 s = "Protocol mismatch.\n";
371 (void) atomicio(write, sock_out, s, strlen(s));
374 log("Bad protocol version identification '%.100s' from %s",
375 client_version_string, get_remote_ipaddr());
378 debug("Client protocol version %d.%d; client software version %.100s",
379 remote_major, remote_minor, remote_version);
381 compat_datafellows(remote_version);
383 if (datafellows & SSH_BUG_SCANNER) {
384 log("scanned from %s with %s. Don't panic.",
385 get_remote_ipaddr(), client_version_string);
390 switch(remote_major) {
392 if (remote_minor == 99) {
393 if (options.protocol & SSH_PROTO_2)
399 if (!(options.protocol & SSH_PROTO_1)) {
403 if (remote_minor < 3) {
404 packet_disconnect("Your ssh version is too old and "
405 "is no longer supported. Please install a newer version.");
406 } else if (remote_minor == 3) {
407 /* note that this disables agent-forwarding */
412 if (options.protocol & SSH_PROTO_2) {
421 chop(server_version_string);
422 debug("Local version string %.200s", server_version_string);
425 s = "Protocol major versions differ.\n";
426 (void) atomicio(write, sock_out, s, strlen(s));
429 log("Protocol major versions differ for %s: %.200s vs. %.200s",
431 server_version_string, client_version_string);
435 packet_set_ssh2_format();
439 /* Destroy the host and server keys. They will no longer be needed. */
441 destroy_sensitive_data(void)
445 if (sensitive_data.server_key) {
446 key_free(sensitive_data.server_key);
447 sensitive_data.server_key = NULL;
449 for(i = 0; i < options.num_host_key_files; i++) {
450 if (sensitive_data.host_keys[i]) {
451 key_free(sensitive_data.host_keys[i]);
452 sensitive_data.host_keys[i] = NULL;
455 sensitive_data.ssh1_host_key = NULL;
456 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
460 list_hostkey_types(void)
462 static char buf[1024];
465 for(i = 0; i < options.num_host_key_files; i++) {
466 Key *key = sensitive_data.host_keys[i];
472 strlcat(buf, key_ssh_name(key), sizeof buf);
473 strlcat(buf, ",", sizeof buf);
478 if (i > 0 && buf[i-1] == ',')
480 debug("list_hostkey_types: %s", buf);
485 get_hostkey_by_type(int type)
488 for(i = 0; i < options.num_host_key_files; i++) {
489 Key *key = sensitive_data.host_keys[i];
490 if (key != NULL && key->type == type)
497 * returns 1 if connection should be dropped, 0 otherwise.
498 * dropping starts at connection #max_startups_begin with a probability
499 * of (max_startups_rate/100). the probability increases linearly until
500 * all connections are dropped for startups > max_startups
503 drop_connection(int startups)
507 if (startups < options.max_startups_begin)
509 if (startups >= options.max_startups)
511 if (options.max_startups_rate == 100)
514 p = 100 - options.max_startups_rate;
515 p *= startups - options.max_startups_begin;
516 p /= (double) (options.max_startups - options.max_startups_begin);
517 p += options.max_startups_rate;
519 r = arc4random() / (double) UINT_MAX;
521 debug("drop_connection: p %g, r %g", p, r);
522 return (r < p) ? 1 : 0;
525 int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
526 int startup_pipe; /* in child */
529 * Main program for the daemon.
532 main(int ac, char **av)
536 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
540 struct sockaddr_storage from;
541 const char *remote_ip;
544 struct linger linger;
546 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
547 int listen_sock, maxfd;
551 int ret, key_used = 0;
553 __progname = get_progname(av[0]);
560 /* Initialize configuration options to their default values. */
561 initialize_server_options(&options);
563 /* Parse command-line arguments. */
564 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDiqQ46")) != -1) {
573 config_file_name = optarg;
576 if (0 == debug_flag) {
578 options.log_level = SYSLOG_LEVEL_DEBUG1;
579 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
582 fprintf(stderr, "Too high debugging level.\n");
596 options.log_level = SYSLOG_LEVEL_QUIET;
599 options.server_key_bits = atoi(optarg);
602 options.ports_from_cmdline = 1;
603 if (options.num_ports >= MAX_PORTS) {
604 fprintf(stderr, "too many ports.\n");
607 options.ports[options.num_ports++] = atoi(optarg);
610 options.login_grace_time = atoi(optarg);
613 options.key_regeneration_time = atoi(optarg);
616 if (options.num_host_key_files >= MAX_HOSTKEYS) {
617 fprintf(stderr, "too many host keys.\n");
620 options.host_key_files[options.num_host_key_files++] = optarg;
623 client_version_string = optarg;
624 /* only makes sense with inetd_flag, i.e. no listen() */
628 utmp_len = atoi(optarg);
632 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
633 fprintf(stderr, "Usage: %s [options]\n", __progname);
634 fprintf(stderr, "Options:\n");
635 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
636 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
637 fprintf(stderr, " -i Started from inetd\n");
638 fprintf(stderr, " -D Do not fork into daemon mode\n");
639 fprintf(stderr, " -q Quiet (no logging)\n");
640 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
641 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
642 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
643 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
644 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
645 _PATH_HOST_KEY_FILE);
646 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
647 fprintf(stderr, " -4 Use IPv4 only\n");
648 fprintf(stderr, " -6 Use IPv6 only\n");
652 SSLeay_add_all_algorithms();
655 * Force logging to stderr until we have loaded the private host
656 * key (unless started from inetd)
659 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
660 options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
665 /* Read server configuration options from the configuration file. */
666 read_server_config(&options, config_file_name);
668 /* Fill in default values for those options not explicitly set. */
669 fill_default_server_options(&options);
671 /* Check that there are no remaining arguments. */
673 fprintf(stderr, "Extra argument %s.\n", av[optind]);
677 debug("sshd version %.100s", SSH_VERSION);
679 /* load private host keys */
680 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
681 for(i = 0; i < options.num_host_key_files; i++)
682 sensitive_data.host_keys[i] = NULL;
683 sensitive_data.server_key = NULL;
684 sensitive_data.ssh1_host_key = NULL;
685 sensitive_data.have_ssh1_key = 0;
686 sensitive_data.have_ssh2_key = 0;
688 for(i = 0; i < options.num_host_key_files; i++) {
689 key = key_load_private(options.host_key_files[i], "", NULL);
690 sensitive_data.host_keys[i] = key;
692 error("Could not load host key: %.200s: %.100s",
693 options.host_key_files[i], strerror(errno));
694 sensitive_data.host_keys[i] = NULL;
699 sensitive_data.ssh1_host_key = key;
700 sensitive_data.have_ssh1_key = 1;
704 sensitive_data.have_ssh2_key = 1;
707 debug("private host key: #%d type %d %s", i, key->type,
710 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
711 log("Disabling protocol version 1. Could not load host key");
712 options.protocol &= ~SSH_PROTO_1;
714 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
715 log("Disabling protocol version 2. Could not load host key");
716 options.protocol &= ~SSH_PROTO_2;
718 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
719 log("sshd: no hostkeys available -- exiting.");
723 /* Check certain values for sanity. */
724 if (options.protocol & SSH_PROTO_1) {
725 if (options.server_key_bits < 512 ||
726 options.server_key_bits > 32768) {
727 fprintf(stderr, "Bad server key size.\n");
731 * Check that server and host key lengths differ sufficiently. This
732 * is necessary to make double encryption work with rsaref. Oh, I
733 * hate software patents. I dont know if this can go? Niels
735 if (options.server_key_bits >
736 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
737 options.server_key_bits <
738 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
739 options.server_key_bits =
740 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
741 debug("Forcing server key to %d bits to make it differ from host key.",
742 options.server_key_bits);
746 #ifdef HAVE_SCO_PROTECTED_PW
747 (void) set_auth_parameters(ac, av);
750 /* Initialize the log (it is reinitialized below in case we forked). */
751 if (debug_flag && !inetd_flag)
753 log_init(__progname, options.log_level, options.log_facility, log_stderr);
756 * If not in debugging mode, and not started from inetd, disconnect
757 * from the controlling terminal, and fork. The original process
760 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
763 #endif /* TIOCNOTTY */
764 if (daemon(0, 0) < 0)
765 fatal("daemon() failed: %.200s", strerror(errno));
767 /* Disconnect from the controlling tty. */
769 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
771 (void) ioctl(fd, TIOCNOTTY, NULL);
774 #endif /* TIOCNOTTY */
776 /* Reinitialize the log (because of the fork above). */
777 log_init(__progname, options.log_level, options.log_facility, log_stderr);
779 /* Initialize the random number generator. */
782 /* Chdir to the root directory so that the current disk can be
783 unmounted if desired. */
787 signal(SIGPIPE, SIG_IGN);
789 /* Start listening for a socket, unless started from inetd. */
792 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
798 * We intentionally do not close the descriptors 0, 1, and 2
799 * as our code for setting the descriptors won\'t work if
800 * ttyfd happens to be one of those.
802 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
803 if (options.protocol & SSH_PROTO_1)
804 generate_ephemeral_server_key();
806 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
807 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
809 if (num_listen_socks >= MAX_LISTEN_SOCKS)
810 fatal("Too many listen sockets. "
811 "Enlarge MAX_LISTEN_SOCKS");
812 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
813 ntop, sizeof(ntop), strport, sizeof(strport),
814 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
815 error("getnameinfo failed");
818 /* Create socket for listening. */
819 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
820 if (listen_sock < 0) {
821 /* kernel may not support ipv6 */
822 verbose("socket: %.100s", strerror(errno));
825 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
826 error("listen_sock O_NONBLOCK: %s", strerror(errno));
831 * Set socket options. We try to make the port
832 * reusable and have it close as fast as possible
833 * without waiting in unnecessary wait states on
836 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
837 (void *) &on, sizeof(on));
840 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
841 (void *) &linger, sizeof(linger));
843 debug("Bind to port %s on %s.", strport, ntop);
845 /* Bind the socket to the desired port. */
846 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
848 error("Bind to port %s on %s failed: %.200s.",
849 strport, ntop, strerror(errno));
853 listen_socks[num_listen_socks] = listen_sock;
856 /* Start listening on the port. */
857 log("Server listening on %s port %s.", ntop, strport);
858 if (listen(listen_sock, 5) < 0)
859 fatal("listen: %.100s", strerror(errno));
862 freeaddrinfo(options.listen_addrs);
864 if (!num_listen_socks)
865 fatal("Cannot bind any address.");
869 * Record our pid in /var/run/sshd.pid to make it
870 * easier to kill the correct sshd. We don't want to
871 * do this before the bind above because the bind will
872 * fail if there already is a daemon, and this will
873 * overwrite any old pid in the file.
875 f = fopen(options.pid_file, "wb");
877 fprintf(f, "%u\n", (u_int) getpid());
881 if (options.protocol & SSH_PROTO_1)
882 generate_ephemeral_server_key();
884 /* Arrange to restart on SIGHUP. The handler needs listen_sock. */
885 signal(SIGHUP, sighup_handler);
887 signal(SIGTERM, sigterm_handler);
888 signal(SIGQUIT, sigterm_handler);
890 /* Arrange SIGCHLD to be caught. */
891 signal(SIGCHLD, main_sigchld_handler);
893 /* setup fd set for listen */
896 for (i = 0; i < num_listen_socks; i++)
897 if (listen_socks[i] > maxfd)
898 maxfd = listen_socks[i];
899 /* pipes connected to unauthenticated childs */
900 startup_pipes = xmalloc(options.max_startups * sizeof(int));
901 for (i = 0; i < options.max_startups; i++)
902 startup_pipes[i] = -1;
905 * Stay listening for connections until the system crashes or
906 * the daemon is killed with a signal.
913 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
914 fdset = (fd_set *)xmalloc(fdsetsz);
915 memset(fdset, 0, fdsetsz);
917 for (i = 0; i < num_listen_socks; i++)
918 FD_SET(listen_socks[i], fdset);
919 for (i = 0; i < options.max_startups; i++)
920 if (startup_pipes[i] != -1)
921 FD_SET(startup_pipes[i], fdset);
923 /* Wait in select until there is a connection. */
924 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
925 if (ret < 0 && errno != EINTR)
926 error("select: %.100s", strerror(errno));
927 if (key_used && key_do_regen) {
928 generate_ephemeral_server_key();
935 for (i = 0; i < options.max_startups; i++)
936 if (startup_pipes[i] != -1 &&
937 FD_ISSET(startup_pipes[i], fdset)) {
939 * the read end of the pipe is ready
940 * if the child has closed the pipe
941 * after successful authentication
942 * or if the child has died
944 close(startup_pipes[i]);
945 startup_pipes[i] = -1;
948 for (i = 0; i < num_listen_socks; i++) {
949 if (!FD_ISSET(listen_socks[i], fdset))
951 fromlen = sizeof(from);
952 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
955 if (errno != EINTR && errno != EWOULDBLOCK)
956 error("accept: %.100s", strerror(errno));
959 if (fcntl(newsock, F_SETFL, 0) < 0) {
960 error("newsock del O_NONBLOCK: %s", strerror(errno));
963 if (drop_connection(startups) == 1) {
964 debug("drop connection #%d", startups);
968 if (pipe(startup_p) == -1) {
973 for (j = 0; j < options.max_startups; j++)
974 if (startup_pipes[j] == -1) {
975 startup_pipes[j] = startup_p[0];
976 if (maxfd < startup_p[0])
977 maxfd = startup_p[0];
983 * Got connection. Fork a child to handle it, unless
984 * we are in debugging mode.
988 * In debugging mode. Close the listening
989 * socket, and start processing the
990 * connection without forking.
992 debug("Server will not fork when running in debugging mode.");
993 close_listen_socks();
1001 * Normal production daemon. Fork, and have
1002 * the child process the connection. The
1003 * parent continues listening.
1005 if ((pid = fork()) == 0) {
1007 * Child. Close the listening and max_startup
1008 * sockets. Start using the accepted socket.
1009 * Reinitialize logging (since our pid has
1010 * changed). We break out of the loop to handle
1013 startup_pipe = startup_p[1];
1014 for (j = 0; j < options.max_startups; j++)
1015 if (startup_pipes[j] != -1)
1016 close(startup_pipes[j]);
1017 close_listen_socks();
1020 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1025 /* Parent. Stay in the loop. */
1027 error("fork: %.100s", strerror(errno));
1029 debug("Forked child %d.", pid);
1031 close(startup_p[1]);
1033 /* Mark that the key has been used (it was "given" to the child). */
1034 if ((options.protocol & SSH_PROTO_1) &&
1036 /* Schedule server key regeneration alarm. */
1037 signal(SIGALRM, key_regeneration_alarm);
1038 alarm(options.key_regeneration_time);
1044 /* Close the new socket (the child is now taking care of it). */
1047 /* child process check (or debug mode) */
1048 if (num_listen_socks < 0)
1053 /* This is the child processing a new connection. */
1056 * Disable the key regeneration alarm. We will not regenerate the
1057 * key since we are no longer in a position to give it to anyone. We
1058 * will not restart on SIGHUP since it no longer makes sense.
1061 signal(SIGALRM, SIG_DFL);
1062 signal(SIGHUP, SIG_DFL);
1063 signal(SIGTERM, SIG_DFL);
1064 signal(SIGQUIT, SIG_DFL);
1065 signal(SIGCHLD, SIG_DFL);
1066 signal(SIGINT, SIG_DFL);
1069 * Set socket options for the connection. We want the socket to
1070 * close as fast as possible without waiting for anything. If the
1071 * connection is not a socket, these will do nothing.
1073 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1075 linger.l_linger = 5;
1076 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1078 /* Set keepalives if requested. */
1079 if (options.keepalives &&
1080 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1082 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1085 * Register our connection. This turns encryption off because we do
1088 packet_set_connection(sock_in, sock_out);
1090 remote_port = get_remote_port();
1091 remote_ip = get_remote_ipaddr();
1093 /* Check whether logins are denied from this host. */
1095 /* XXX LIBWRAP noes not know about IPv6 */
1097 struct request_info req;
1099 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, NULL);
1102 if (!hosts_access(&req)) {
1107 /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
1109 #endif /* LIBWRAP */
1110 /* Log the connection. */
1111 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1114 * We don\'t want to listen forever unless the other side
1115 * successfully authenticates itself. So we set up an alarm which is
1116 * cleared after successful authentication. A limit of zero
1117 * indicates no limit. Note that we don\'t set the alarm in debugging
1118 * mode; it is just annoying to have the server exit just when you
1119 * are about to discover the bug.
1121 signal(SIGALRM, grace_alarm_handler);
1123 alarm(options.login_grace_time);
1125 sshd_exchange_identification(sock_in, sock_out);
1127 * Check that the connection comes from a privileged port.
1128 * Rhosts-Authentication only makes sense from priviledged
1129 * programs. Of course, if the intruder has root access on his local
1130 * machine, he can connect from any port. So do not use these
1131 * authentication methods from machines that you do not trust.
1133 if (remote_port >= IPPORT_RESERVED ||
1134 remote_port < IPPORT_RESERVED / 2) {
1135 debug("Rhosts Authentication disabled, "
1136 "originating port not trusted.");
1137 options.rhosts_authentication = 0;
1140 if (!packet_connection_is_ipv4() &&
1141 options.kerberos_authentication) {
1142 debug("Kerberos Authentication disabled, only available for IPv4.");
1143 options.kerberos_authentication = 0;
1147 /* If machine has AFS, set process authentication group. */
1154 packet_set_nonblocking();
1156 /* perform the key exchange */
1157 /* authenticate user and start session */
1160 do_authentication2();
1163 do_authentication();
1167 /* Cleanup user's ticket cache file. */
1168 if (options.kerberos_ticket_cleanup)
1172 /* The connection has been terminated. */
1173 verbose("Closing connection to %.100s", remote_ip);
1177 #endif /* USE_PAM */
1192 BIGNUM *session_key_int;
1193 u_char session_key[SSH_SESSION_KEY_LENGTH];
1195 u_int cipher_type, auth_mask, protocol_flags;
1199 * Generate check bytes that the client must send back in the user
1200 * packet in order for it to be accepted; this is used to defy ip
1201 * spoofing attacks. Note that this only works against somebody
1202 * doing IP spoofing from a remote machine; any machine on the local
1203 * network can still see outgoing packets and catch the random
1204 * cookie. This only affects rhosts authentication, and this is one
1205 * of the reasons why it is inherently insecure.
1207 for (i = 0; i < 8; i++) {
1209 rand = arc4random();
1210 cookie[i] = rand & 0xff;
1215 * Send our public key. We include in the packet 64 bits of random
1216 * data that must be matched in the reply in order to prevent IP
1219 packet_start(SSH_SMSG_PUBLIC_KEY);
1220 for (i = 0; i < 8; i++)
1221 packet_put_char(cookie[i]);
1223 /* Store our public server RSA key. */
1224 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1225 packet_put_bignum(sensitive_data.server_key->rsa->e);
1226 packet_put_bignum(sensitive_data.server_key->rsa->n);
1228 /* Store our public host RSA key. */
1229 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1230 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1231 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1233 /* Put protocol flags. */
1234 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1236 /* Declare which ciphers we support. */
1237 packet_put_int(cipher_mask_ssh1(0));
1239 /* Declare supported authentication types. */
1241 if (options.rhosts_authentication)
1242 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1243 if (options.rhosts_rsa_authentication)
1244 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1245 if (options.rsa_authentication)
1246 auth_mask |= 1 << SSH_AUTH_RSA;
1248 if (options.kerberos_authentication)
1249 auth_mask |= 1 << SSH_AUTH_KERBEROS;
1252 if (options.kerberos_tgt_passing)
1253 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1254 if (options.afs_token_passing)
1255 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1257 if (options.challenge_reponse_authentication == 1)
1258 auth_mask |= 1 << SSH_AUTH_TIS;
1259 if (options.password_authentication)
1260 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1261 packet_put_int(auth_mask);
1263 /* Send the packet and wait for it to be sent. */
1265 packet_write_wait();
1267 debug("Sent %d bit server key and %d bit host key.",
1268 BN_num_bits(sensitive_data.server_key->rsa->n),
1269 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1271 /* Read clients reply (cipher type and session key). */
1272 packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
1274 /* Get cipher type and check whether we accept this. */
1275 cipher_type = packet_get_char();
1277 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1278 packet_disconnect("Warning: client selects unsupported cipher.");
1280 /* Get check bytes from the packet. These must match those we
1281 sent earlier with the public key packet. */
1282 for (i = 0; i < 8; i++)
1283 if (cookie[i] != packet_get_char())
1284 packet_disconnect("IP Spoofing check bytes do not match.");
1286 debug("Encryption type: %.200s", cipher_name(cipher_type));
1288 /* Get the encrypted integer. */
1289 session_key_int = BN_new();
1290 packet_get_bignum(session_key_int, &slen);
1292 protocol_flags = packet_get_int();
1293 packet_set_protocol_flags(protocol_flags);
1295 packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
1298 * Decrypt it using our private server key and private host key (key
1299 * with larger modulus first).
1301 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1302 /* Server key has bigger modulus. */
1303 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1304 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1305 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1306 get_remote_ipaddr(),
1307 BN_num_bits(sensitive_data.server_key->rsa->n),
1308 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1309 SSH_KEY_BITS_RESERVED);
1311 if (rsa_private_decrypt(session_key_int, session_key_int,
1312 sensitive_data.server_key->rsa) <= 0)
1314 if (rsa_private_decrypt(session_key_int, session_key_int,
1315 sensitive_data.ssh1_host_key->rsa) <= 0)
1318 /* Host key has bigger modulus (or they are equal). */
1319 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1320 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1321 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1322 get_remote_ipaddr(),
1323 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1324 BN_num_bits(sensitive_data.server_key->rsa->n),
1325 SSH_KEY_BITS_RESERVED);
1327 if (rsa_private_decrypt(session_key_int, session_key_int,
1328 sensitive_data.ssh1_host_key->rsa) < 0)
1330 if (rsa_private_decrypt(session_key_int, session_key_int,
1331 sensitive_data.server_key->rsa) < 0)
1335 * Extract session key from the decrypted integer. The key is in the
1336 * least significant 256 bits of the integer; the first byte of the
1337 * key is in the highest bits.
1340 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1341 len = BN_num_bytes(session_key_int);
1342 if (len < 0 || len > sizeof(session_key)) {
1343 error("do_connection: bad session key len from %s: "
1344 "session_key_int %d > sizeof(session_key) %lu",
1345 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1348 memset(session_key, 0, sizeof(session_key));
1349 BN_bn2bin(session_key_int,
1350 session_key + sizeof(session_key) - len);
1352 compute_session_id(session_id, cookie,
1353 sensitive_data.ssh1_host_key->rsa->n,
1354 sensitive_data.server_key->rsa->n);
1356 * Xor the first 16 bytes of the session key with the
1359 for (i = 0; i < 16; i++)
1360 session_key[i] ^= session_id[i];
1364 int bytes = BN_num_bytes(session_key_int);
1365 char *buf = xmalloc(bytes);
1368 log("do_connection: generating a fake encryption key");
1369 BN_bn2bin(session_key_int, buf);
1371 MD5_Update(&md, buf, bytes);
1372 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1373 MD5_Final(session_key, &md);
1375 MD5_Update(&md, session_key, 16);
1376 MD5_Update(&md, buf, bytes);
1377 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1378 MD5_Final(session_key + 16, &md);
1379 memset(buf, 0, bytes);
1381 for (i = 0; i < 16; i++)
1382 session_id[i] = session_key[i] ^ session_key[i + 16];
1384 /* Destroy the private and public keys. They will no longer be needed. */
1385 destroy_sensitive_data();
1387 /* Destroy the decrypted integer. It is no longer needed. */
1388 BN_clear_free(session_key_int);
1390 /* Set the session key. From this on all communications will be encrypted. */
1391 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1393 /* Destroy our copy of the session key. It is no longer needed. */
1394 memset(session_key, 0, sizeof(session_key));
1396 debug("Received session key; encryption turned on.");
1398 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1399 packet_start(SSH_SMSG_SUCCESS);
1401 packet_write_wait();
1405 * SSH2 key exchange: diffie-hellman-group1-sha1
1410 Buffer *server_kexinit;
1411 Buffer *client_kexinit;
1415 char *cprop[PROPOSAL_MAX];
1419 if (options.ciphers != NULL) {
1420 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1421 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1423 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1424 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1425 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1426 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1428 if (options.macs != NULL) {
1429 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1430 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1432 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1434 server_kexinit = kex_init(myproposal);
1435 client_kexinit = xmalloc(sizeof(*client_kexinit));
1436 buffer_init(client_kexinit);
1438 /* algorithm negotiation */
1439 kex_exchange_kexinit(server_kexinit, client_kexinit, cprop);
1440 kex = kex_choose_conf(cprop, myproposal, 1);
1441 for (i = 0; i < PROPOSAL_MAX; i++)
1444 switch (kex->kex_type) {
1446 ssh_dh1_server(kex, client_kexinit, server_kexinit);
1449 ssh_dhgex_server(kex, client_kexinit, server_kexinit);
1452 fatal("Unsupported key exchange %d", kex->kex_type);
1455 debug("send SSH2_MSG_NEWKEYS.");
1456 packet_start(SSH2_MSG_NEWKEYS);
1458 packet_write_wait();
1459 debug("done: send SSH2_MSG_NEWKEYS.");
1461 debug("Wait SSH2_MSG_NEWKEYS.");
1462 packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1463 debug("GOT SSH2_MSG_NEWKEYS.");
1466 /* send 1st encrypted/maced/compressed message */
1467 packet_start(SSH2_MSG_IGNORE);
1468 packet_put_cstring("markus");
1470 packet_write_wait();
1473 debug("done: KEX2.");
1480 /* diffie-hellman-group1-sha1 */
1483 ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1488 int payload_len, dlen;
1490 u_char *signature = NULL;
1491 u_char *server_host_key_blob = NULL;
1496 BIGNUM *shared_secret = 0;
1498 BIGNUM *dh_client_pub = 0;
1501 hostkey = get_hostkey_by_type(kex->hostkey_type);
1502 if (hostkey == NULL)
1503 fatal("Unsupported hostkey type %d", kex->hostkey_type);
1506 /* generate DH key */
1507 dh = dh_new_group1(); /* XXX depends on 'kex' */
1508 dh_gen_key(dh, kex->we_need * 8);
1510 debug("Wait SSH2_MSG_KEXDH_INIT.");
1511 packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
1514 dh_client_pub = BN_new();
1515 if (dh_client_pub == NULL)
1516 fatal("dh_client_pub == NULL");
1517 packet_get_bignum2(dh_client_pub, &dlen);
1520 fprintf(stderr, "\ndh_client_pub= ");
1521 BN_print_fp(stderr, dh_client_pub);
1522 fprintf(stderr, "\n");
1523 debug("bits %d", BN_num_bits(dh_client_pub));
1527 fprintf(stderr, "\np= ");
1528 BN_print_fp(stderr, dh->p);
1529 fprintf(stderr, "\ng= ");
1531 fprintf(stderr, "\npub= ");
1532 BN_print_fp(stderr, dh->pub_key);
1533 fprintf(stderr, "\n");
1534 DHparams_print_fp(stderr, dh);
1536 if (!dh_pub_is_valid(dh, dh_client_pub))
1537 packet_disconnect("bad client public DH value");
1540 kbuf = xmalloc(klen);
1541 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1544 debug("shared secret: len %d/%d", klen, kout);
1545 fprintf(stderr, "shared secret == ");
1546 for (i = 0; i< kout; i++)
1547 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1548 fprintf(stderr, "\n");
1550 shared_secret = BN_new();
1552 BN_bin2bn(kbuf, kout, shared_secret);
1553 memset(kbuf, 0, klen);
1556 /* XXX precompute? */
1557 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1559 /* calc H */ /* XXX depends on 'kex' */
1561 client_version_string,
1562 server_version_string,
1563 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1564 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1565 (char *)server_host_key_blob, sbloblen,
1570 buffer_free(client_kexinit);
1571 buffer_free(server_kexinit);
1572 xfree(client_kexinit);
1573 xfree(server_kexinit);
1574 BN_free(dh_client_pub);
1576 fprintf(stderr, "hash == ");
1577 for (i = 0; i< 20; i++)
1578 fprintf(stderr, "%02x", (hash[i])&0xff);
1579 fprintf(stderr, "\n");
1581 /* save session id := H */
1582 /* XXX hashlen depends on KEX */
1583 session_id2_len = 20;
1584 session_id2 = xmalloc(session_id2_len);
1585 memcpy(session_id2, hash, session_id2_len);
1588 /* XXX hashlen depends on KEX */
1589 key_sign(hostkey, &signature, &slen, hash, 20);
1591 destroy_sensitive_data();
1593 /* send server hostkey, DH pubkey 'f' and singed H */
1594 packet_start(SSH2_MSG_KEXDH_REPLY);
1595 packet_put_string((char *)server_host_key_blob, sbloblen);
1596 packet_put_bignum2(dh->pub_key); /* f */
1597 packet_put_string((char *)signature, slen);
1600 xfree(server_host_key_blob);
1601 packet_write_wait();
1603 kex_derive_keys(kex, hash, shared_secret);
1604 BN_clear_free(shared_secret);
1605 packet_set_kex(kex);
1607 /* have keys, free DH */
1611 /* diffie-hellman-group-exchange-sha1 */
1614 ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1619 int payload_len, dlen;
1620 int slen, nbits, type, min, max;
1621 u_char *signature = NULL;
1622 u_char *server_host_key_blob = NULL;
1627 BIGNUM *shared_secret = 0;
1629 BIGNUM *dh_client_pub = 0;
1632 hostkey = get_hostkey_by_type(kex->hostkey_type);
1633 if (hostkey == NULL)
1634 fatal("Unsupported hostkey type %d", kex->hostkey_type);
1637 debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST.");
1638 type = packet_read(&payload_len);
1639 if (type != SSH2_MSG_KEX_DH_GEX_REQUEST_OLD &&
1640 type != SSH2_MSG_KEX_DH_GEX_REQUEST)
1641 packet_disconnect("Protocol error: expected type %d or %d, got %d",
1642 SSH2_MSG_KEX_DH_GEX_REQUEST_OLD,
1643 SSH2_MSG_KEX_DH_GEX_REQUEST,
1645 if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD) {
1646 nbits = packet_get_int();
1650 min = packet_get_int();
1651 nbits = packet_get_int();
1652 max = packet_get_int();
1654 min = MAX(DH_GRP_MIN, min);
1655 max = MIN(DH_GRP_MAX, max);
1658 if (max < min || nbits < min || max < nbits)
1659 fatal("DH_GEX_REQUEST, bad parameters: %d !< %d !< %d",
1662 dh = choose_dh(min, nbits, max);
1664 packet_disconnect("Protocol error: no matching DH grp found");
1666 debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP.");
1667 packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
1668 packet_put_bignum2(dh->p);
1669 packet_put_bignum2(dh->g);
1671 packet_write_wait();
1673 /* Compute our exchange value in parallel with the client */
1675 dh_gen_key(dh, kex->we_need * 8);
1677 debug("Wait SSH2_MSG_KEX_DH_GEX_INIT.");
1678 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT);
1681 dh_client_pub = BN_new();
1682 if (dh_client_pub == NULL)
1683 fatal("dh_client_pub == NULL");
1684 packet_get_bignum2(dh_client_pub, &dlen);
1687 fprintf(stderr, "\ndh_client_pub= ");
1688 BN_print_fp(stderr, dh_client_pub);
1689 fprintf(stderr, "\n");
1690 debug("bits %d", BN_num_bits(dh_client_pub));
1694 fprintf(stderr, "\np= ");
1695 BN_print_fp(stderr, dh->p);
1696 fprintf(stderr, "\ng= ");
1698 fprintf(stderr, "\npub= ");
1699 BN_print_fp(stderr, dh->pub_key);
1700 fprintf(stderr, "\n");
1701 DHparams_print_fp(stderr, dh);
1703 if (!dh_pub_is_valid(dh, dh_client_pub))
1704 packet_disconnect("bad client public DH value");
1707 kbuf = xmalloc(klen);
1708 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1711 debug("shared secret: len %d/%d", klen, kout);
1712 fprintf(stderr, "shared secret == ");
1713 for (i = 0; i< kout; i++)
1714 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1715 fprintf(stderr, "\n");
1717 shared_secret = BN_new();
1719 BN_bin2bn(kbuf, kout, shared_secret);
1720 memset(kbuf, 0, klen);
1723 /* XXX precompute? */
1724 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1726 if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD) {
1727 /* These values are not included in the hash */
1732 /* calc H */ /* XXX depends on 'kex' */
1733 hash = kex_hash_gex(
1734 client_version_string,
1735 server_version_string,
1736 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1737 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1738 (char *)server_host_key_blob, sbloblen,
1745 buffer_free(client_kexinit);
1746 buffer_free(server_kexinit);
1747 xfree(client_kexinit);
1748 xfree(server_kexinit);
1749 BN_free(dh_client_pub);
1751 fprintf(stderr, "hash == ");
1752 for (i = 0; i< 20; i++)
1753 fprintf(stderr, "%02x", (hash[i])&0xff);
1754 fprintf(stderr, "\n");
1756 /* save session id := H */
1757 /* XXX hashlen depends on KEX */
1758 session_id2_len = 20;
1759 session_id2 = xmalloc(session_id2_len);
1760 memcpy(session_id2, hash, session_id2_len);
1763 /* XXX hashlen depends on KEX */
1764 key_sign(hostkey, &signature, &slen, hash, 20);
1766 destroy_sensitive_data();
1768 /* send server hostkey, DH pubkey 'f' and singed H */
1769 packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
1770 packet_put_string((char *)server_host_key_blob, sbloblen);
1771 packet_put_bignum2(dh->pub_key); /* f */
1772 packet_put_string((char *)signature, slen);
1775 xfree(server_host_key_blob);
1776 packet_write_wait();
1778 kex_derive_keys(kex, hash, shared_secret);
1779 BN_clear_free(shared_secret);
1780 packet_set_kex(kex);
1782 /* have keys, free DH */