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 1.178 2001/03/23 14:28:32 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; /* 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') {
348 /* Kludge for F-Secure Macintosh < 1.0.2 */
350 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
354 if (buf[i] == '\n') {
359 buf[sizeof(buf) - 1] = 0;
360 client_version_string = xstrdup(buf);
364 * Check that the versions match. In future this might accept
365 * several versions and set appropriate flags to handle them.
367 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
368 &remote_major, &remote_minor, remote_version) != 3) {
369 s = "Protocol mismatch.\n";
370 (void) atomicio(write, sock_out, s, strlen(s));
373 log("Bad protocol version identification '%.100s' from %s",
374 client_version_string, get_remote_ipaddr());
377 debug("Client protocol version %d.%d; client software version %.100s",
378 remote_major, remote_minor, remote_version);
380 compat_datafellows(remote_version);
382 if (datafellows & SSH_BUG_SCANNER) {
383 log("scanned from %s with %s. Don't panic.",
384 get_remote_ipaddr(), client_version_string);
389 switch(remote_major) {
391 if (remote_minor == 99) {
392 if (options.protocol & SSH_PROTO_2)
398 if (!(options.protocol & SSH_PROTO_1)) {
402 if (remote_minor < 3) {
403 packet_disconnect("Your ssh version is too old and "
404 "is no longer supported. Please install a newer version.");
405 } else if (remote_minor == 3) {
406 /* note that this disables agent-forwarding */
411 if (options.protocol & SSH_PROTO_2) {
420 chop(server_version_string);
421 debug("Local version string %.200s", server_version_string);
424 s = "Protocol major versions differ.\n";
425 (void) atomicio(write, sock_out, s, strlen(s));
428 log("Protocol major versions differ for %s: %.200s vs. %.200s",
430 server_version_string, client_version_string);
434 packet_set_ssh2_format();
438 /* Destroy the host and server keys. They will no longer be needed. */
440 destroy_sensitive_data(void)
444 if (sensitive_data.server_key) {
445 key_free(sensitive_data.server_key);
446 sensitive_data.server_key = NULL;
448 for(i = 0; i < options.num_host_key_files; i++) {
449 if (sensitive_data.host_keys[i]) {
450 key_free(sensitive_data.host_keys[i]);
451 sensitive_data.host_keys[i] = NULL;
454 sensitive_data.ssh1_host_key = NULL;
455 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
458 load_private_key_autodetect(const char *filename)
462 Key *public, *private;
464 if (stat(filename, &st) < 0) {
469 * try to load the public key. right now this only works for RSA1,
470 * since SSH2 keys are fully encrypted
473 public = key_new(type);
474 if (!load_public_key(filename, public, NULL)) {
475 /* ok, so we will assume this is 'some' key */
480 /* Ok, try key with empty passphrase */
481 private = key_new(type);
482 if (load_private_key(filename, "", private, NULL)) {
483 debug("load_private_key_autodetect: type %d %s",
484 private->type, key_type(private));
492 list_hostkey_types(void)
494 static char buf[1024];
497 for(i = 0; i < options.num_host_key_files; i++) {
498 Key *key = sensitive_data.host_keys[i];
504 strlcat(buf, key_ssh_name(key), sizeof buf);
505 strlcat(buf, ",", sizeof buf);
510 if (i > 0 && buf[i-1] == ',')
512 debug("list_hostkey_types: %s", buf);
517 get_hostkey_by_type(int type)
520 for(i = 0; i < options.num_host_key_files; i++) {
521 Key *key = sensitive_data.host_keys[i];
522 if (key != NULL && key->type == type)
529 * returns 1 if connection should be dropped, 0 otherwise.
530 * dropping starts at connection #max_startups_begin with a probability
531 * of (max_startups_rate/100). the probability increases linearly until
532 * all connections are dropped for startups > max_startups
535 drop_connection(int startups)
539 if (startups < options.max_startups_begin)
541 if (startups >= options.max_startups)
543 if (options.max_startups_rate == 100)
546 p = 100 - options.max_startups_rate;
547 p *= startups - options.max_startups_begin;
548 p /= (double) (options.max_startups - options.max_startups_begin);
549 p += options.max_startups_rate;
551 r = arc4random() / (double) UINT_MAX;
553 debug("drop_connection: p %g, r %g", p, r);
554 return (r < p) ? 1 : 0;
557 int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
558 int startup_pipe; /* in child */
561 * Main program for the daemon.
564 main(int ac, char **av)
568 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
572 struct sockaddr_storage from;
573 const char *remote_ip;
576 struct linger linger;
578 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
579 int listen_sock, maxfd;
582 int ret, key_used = 0;
584 __progname = get_progname(av[0]);
591 /* Initialize configuration options to their default values. */
592 initialize_server_options(&options);
594 /* Parse command-line arguments. */
595 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDiqQ46")) != -1) {
604 config_file_name = optarg;
607 if (0 == debug_flag) {
609 options.log_level = SYSLOG_LEVEL_DEBUG1;
610 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
613 fprintf(stderr, "Too high debugging level.\n");
627 options.log_level = SYSLOG_LEVEL_QUIET;
630 options.server_key_bits = atoi(optarg);
633 options.ports_from_cmdline = 1;
634 if (options.num_ports >= MAX_PORTS) {
635 fprintf(stderr, "too many ports.\n");
638 options.ports[options.num_ports++] = atoi(optarg);
641 options.login_grace_time = atoi(optarg);
644 options.key_regeneration_time = atoi(optarg);
647 if (options.num_host_key_files >= MAX_HOSTKEYS) {
648 fprintf(stderr, "too many host keys.\n");
651 options.host_key_files[options.num_host_key_files++] = optarg;
654 client_version_string = optarg;
655 /* only makes sense with inetd_flag, i.e. no listen() */
659 utmp_len = atoi(optarg);
663 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
664 fprintf(stderr, "Usage: %s [options]\n", __progname);
665 fprintf(stderr, "Options:\n");
666 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
667 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
668 fprintf(stderr, " -i Started from inetd\n");
669 fprintf(stderr, " -D Do not fork into daemon mode\n");
670 fprintf(stderr, " -q Quiet (no logging)\n");
671 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
672 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
673 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
674 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
675 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
676 _PATH_HOST_KEY_FILE);
677 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
678 fprintf(stderr, " -4 Use IPv4 only\n");
679 fprintf(stderr, " -6 Use IPv6 only\n");
685 * Force logging to stderr until we have loaded the private host
686 * key (unless started from inetd)
689 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
690 options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
695 /* Read server configuration options from the configuration file. */
696 read_server_config(&options, config_file_name);
698 /* Fill in default values for those options not explicitly set. */
699 fill_default_server_options(&options);
701 /* Check that there are no remaining arguments. */
703 fprintf(stderr, "Extra argument %s.\n", av[optind]);
707 debug("sshd version %.100s", SSH_VERSION);
709 /* load private host keys */
710 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
711 for(i = 0; i < options.num_host_key_files; i++)
712 sensitive_data.host_keys[i] = NULL;
713 sensitive_data.server_key = NULL;
714 sensitive_data.ssh1_host_key = NULL;
715 sensitive_data.have_ssh1_key = 0;
716 sensitive_data.have_ssh2_key = 0;
718 for(i = 0; i < options.num_host_key_files; i++) {
719 Key *key = load_private_key_autodetect(options.host_key_files[i]);
721 error("Could not load host key: %.200s: %.100s",
722 options.host_key_files[i], strerror(errno));
727 sensitive_data.ssh1_host_key = key;
728 sensitive_data.have_ssh1_key = 1;
732 sensitive_data.have_ssh2_key = 1;
735 sensitive_data.host_keys[i] = key;
737 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
738 log("Disabling protocol version 1. Could not load host key");
739 options.protocol &= ~SSH_PROTO_1;
741 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
742 log("Disabling protocol version 2. Could not load host key");
743 options.protocol &= ~SSH_PROTO_2;
745 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
746 log("sshd: no hostkeys available -- exiting.");
750 /* Check certain values for sanity. */
751 if (options.protocol & SSH_PROTO_1) {
752 if (options.server_key_bits < 512 ||
753 options.server_key_bits > 32768) {
754 fprintf(stderr, "Bad server key size.\n");
758 * Check that server and host key lengths differ sufficiently. This
759 * is necessary to make double encryption work with rsaref. Oh, I
760 * hate software patents. I dont know if this can go? Niels
762 if (options.server_key_bits >
763 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
764 options.server_key_bits <
765 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
766 options.server_key_bits =
767 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
768 debug("Forcing server key to %d bits to make it differ from host key.",
769 options.server_key_bits);
773 #ifdef HAVE_SCO_PROTECTED_PW
774 (void) set_auth_parameters(ac, av);
777 /* Initialize the log (it is reinitialized below in case we forked). */
778 if (debug_flag && !inetd_flag)
780 log_init(__progname, options.log_level, options.log_facility, log_stderr);
783 * If not in debugging mode, and not started from inetd, disconnect
784 * from the controlling terminal, and fork. The original process
787 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
790 #endif /* TIOCNOTTY */
791 if (daemon(0, 0) < 0)
792 fatal("daemon() failed: %.200s", strerror(errno));
794 /* Disconnect from the controlling tty. */
796 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
798 (void) ioctl(fd, TIOCNOTTY, NULL);
801 #endif /* TIOCNOTTY */
803 /* Reinitialize the log (because of the fork above). */
804 log_init(__progname, options.log_level, options.log_facility, log_stderr);
806 /* Initialize the random number generator. */
809 /* Chdir to the root directory so that the current disk can be
810 unmounted if desired. */
814 signal(SIGPIPE, SIG_IGN);
816 /* Start listening for a socket, unless started from inetd. */
819 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
825 * We intentionally do not close the descriptors 0, 1, and 2
826 * as our code for setting the descriptors won\'t work if
827 * ttyfd happens to be one of those.
829 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
830 if (options.protocol & SSH_PROTO_1)
831 generate_ephemeral_server_key();
833 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
834 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
836 if (num_listen_socks >= MAX_LISTEN_SOCKS)
837 fatal("Too many listen sockets. "
838 "Enlarge MAX_LISTEN_SOCKS");
839 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
840 ntop, sizeof(ntop), strport, sizeof(strport),
841 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
842 error("getnameinfo failed");
845 /* Create socket for listening. */
846 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
847 if (listen_sock < 0) {
848 /* kernel may not support ipv6 */
849 verbose("socket: %.100s", strerror(errno));
852 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
853 error("listen_sock O_NONBLOCK: %s", strerror(errno));
858 * Set socket options. We try to make the port
859 * reusable and have it close as fast as possible
860 * without waiting in unnecessary wait states on
863 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
864 (void *) &on, sizeof(on));
867 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
868 (void *) &linger, sizeof(linger));
870 debug("Bind to port %s on %s.", strport, ntop);
872 /* Bind the socket to the desired port. */
873 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
875 error("Bind to port %s on %s failed: %.200s.",
876 strport, ntop, strerror(errno));
880 listen_socks[num_listen_socks] = listen_sock;
883 /* Start listening on the port. */
884 log("Server listening on %s port %s.", ntop, strport);
885 if (listen(listen_sock, 5) < 0)
886 fatal("listen: %.100s", strerror(errno));
889 freeaddrinfo(options.listen_addrs);
891 if (!num_listen_socks)
892 fatal("Cannot bind any address.");
896 * Record our pid in /var/run/sshd.pid to make it
897 * easier to kill the correct sshd. We don't want to
898 * do this before the bind above because the bind will
899 * fail if there already is a daemon, and this will
900 * overwrite any old pid in the file.
902 f = fopen(options.pid_file, "wb");
904 fprintf(f, "%u\n", (u_int) getpid());
908 if (options.protocol & SSH_PROTO_1)
909 generate_ephemeral_server_key();
911 /* Arrange to restart on SIGHUP. The handler needs listen_sock. */
912 signal(SIGHUP, sighup_handler);
914 signal(SIGTERM, sigterm_handler);
915 signal(SIGQUIT, sigterm_handler);
917 /* Arrange SIGCHLD to be caught. */
918 signal(SIGCHLD, main_sigchld_handler);
920 /* setup fd set for listen */
923 for (i = 0; i < num_listen_socks; i++)
924 if (listen_socks[i] > maxfd)
925 maxfd = listen_socks[i];
926 /* pipes connected to unauthenticated childs */
927 startup_pipes = xmalloc(options.max_startups * sizeof(int));
928 for (i = 0; i < options.max_startups; i++)
929 startup_pipes[i] = -1;
932 * Stay listening for connections until the system crashes or
933 * the daemon is killed with a signal.
940 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
941 fdset = (fd_set *)xmalloc(fdsetsz);
942 memset(fdset, 0, fdsetsz);
944 for (i = 0; i < num_listen_socks; i++)
945 FD_SET(listen_socks[i], fdset);
946 for (i = 0; i < options.max_startups; i++)
947 if (startup_pipes[i] != -1)
948 FD_SET(startup_pipes[i], fdset);
950 /* Wait in select until there is a connection. */
951 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
952 if (ret < 0 && errno != EINTR)
953 error("select: %.100s", strerror(errno));
954 if (key_used && key_do_regen) {
955 generate_ephemeral_server_key();
962 for (i = 0; i < options.max_startups; i++)
963 if (startup_pipes[i] != -1 &&
964 FD_ISSET(startup_pipes[i], fdset)) {
966 * the read end of the pipe is ready
967 * if the child has closed the pipe
968 * after successful authentication
969 * or if the child has died
971 close(startup_pipes[i]);
972 startup_pipes[i] = -1;
975 for (i = 0; i < num_listen_socks; i++) {
976 if (!FD_ISSET(listen_socks[i], fdset))
978 fromlen = sizeof(from);
979 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
982 if (errno != EINTR && errno != EWOULDBLOCK)
983 error("accept: %.100s", strerror(errno));
986 if (fcntl(newsock, F_SETFL, 0) < 0) {
987 error("newsock del O_NONBLOCK: %s", strerror(errno));
990 if (drop_connection(startups) == 1) {
991 debug("drop connection #%d", startups);
995 if (pipe(startup_p) == -1) {
1000 for (j = 0; j < options.max_startups; j++)
1001 if (startup_pipes[j] == -1) {
1002 startup_pipes[j] = startup_p[0];
1003 if (maxfd < startup_p[0])
1004 maxfd = startup_p[0];
1010 * Got connection. Fork a child to handle it, unless
1011 * we are in debugging mode.
1015 * In debugging mode. Close the listening
1016 * socket, and start processing the
1017 * connection without forking.
1019 debug("Server will not fork when running in debugging mode.");
1020 close_listen_socks();
1028 * Normal production daemon. Fork, and have
1029 * the child process the connection. The
1030 * parent continues listening.
1032 if ((pid = fork()) == 0) {
1034 * Child. Close the listening and max_startup
1035 * sockets. Start using the accepted socket.
1036 * Reinitialize logging (since our pid has
1037 * changed). We break out of the loop to handle
1040 startup_pipe = startup_p[1];
1041 for (j = 0; j < options.max_startups; j++)
1042 if (startup_pipes[j] != -1)
1043 close(startup_pipes[j]);
1044 close_listen_socks();
1047 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1052 /* Parent. Stay in the loop. */
1054 error("fork: %.100s", strerror(errno));
1056 debug("Forked child %d.", pid);
1058 close(startup_p[1]);
1060 /* Mark that the key has been used (it was "given" to the child). */
1061 if ((options.protocol & SSH_PROTO_1) &&
1063 /* Schedule server key regeneration alarm. */
1064 signal(SIGALRM, key_regeneration_alarm);
1065 alarm(options.key_regeneration_time);
1071 /* Close the new socket (the child is now taking care of it). */
1074 /* child process check (or debug mode) */
1075 if (num_listen_socks < 0)
1080 /* This is the child processing a new connection. */
1083 * Disable the key regeneration alarm. We will not regenerate the
1084 * key since we are no longer in a position to give it to anyone. We
1085 * will not restart on SIGHUP since it no longer makes sense.
1088 signal(SIGALRM, SIG_DFL);
1089 signal(SIGHUP, SIG_DFL);
1090 signal(SIGTERM, SIG_DFL);
1091 signal(SIGQUIT, SIG_DFL);
1092 signal(SIGCHLD, SIG_DFL);
1093 signal(SIGINT, SIG_DFL);
1096 * Set socket options for the connection. We want the socket to
1097 * close as fast as possible without waiting for anything. If the
1098 * connection is not a socket, these will do nothing.
1100 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1102 linger.l_linger = 5;
1103 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1105 /* Set keepalives if requested. */
1106 if (options.keepalives &&
1107 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1109 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1112 * Register our connection. This turns encryption off because we do
1115 packet_set_connection(sock_in, sock_out);
1117 remote_port = get_remote_port();
1118 remote_ip = get_remote_ipaddr();
1120 /* Check whether logins are denied from this host. */
1122 /* XXX LIBWRAP noes not know about IPv6 */
1124 struct request_info req;
1126 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, NULL);
1129 if (!hosts_access(&req)) {
1134 /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
1136 #endif /* LIBWRAP */
1137 /* Log the connection. */
1138 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1141 * We don\'t want to listen forever unless the other side
1142 * successfully authenticates itself. So we set up an alarm which is
1143 * cleared after successful authentication. A limit of zero
1144 * indicates no limit. Note that we don\'t set the alarm in debugging
1145 * mode; it is just annoying to have the server exit just when you
1146 * are about to discover the bug.
1148 signal(SIGALRM, grace_alarm_handler);
1150 alarm(options.login_grace_time);
1152 sshd_exchange_identification(sock_in, sock_out);
1154 * Check that the connection comes from a privileged port.
1155 * Rhosts-Authentication only makes sense from priviledged
1156 * programs. Of course, if the intruder has root access on his local
1157 * machine, he can connect from any port. So do not use these
1158 * authentication methods from machines that you do not trust.
1160 if (remote_port >= IPPORT_RESERVED ||
1161 remote_port < IPPORT_RESERVED / 2) {
1162 debug("Rhosts Authentication disabled, "
1163 "originating port not trusted.");
1164 options.rhosts_authentication = 0;
1167 if (!packet_connection_is_ipv4() &&
1168 options.kerberos_authentication) {
1169 debug("Kerberos Authentication disabled, only available for IPv4.");
1170 options.kerberos_authentication = 0;
1174 /* If machine has AFS, set process authentication group. */
1181 packet_set_nonblocking();
1183 /* perform the key exchange */
1184 /* authenticate user and start session */
1187 do_authentication2();
1190 do_authentication();
1194 /* Cleanup user's ticket cache file. */
1195 if (options.kerberos_ticket_cleanup)
1199 /* The connection has been terminated. */
1200 verbose("Closing connection to %.100s", remote_ip);
1204 #endif /* USE_PAM */
1219 BIGNUM *session_key_int;
1220 u_char session_key[SSH_SESSION_KEY_LENGTH];
1222 u_int cipher_type, auth_mask, protocol_flags;
1226 * Generate check bytes that the client must send back in the user
1227 * packet in order for it to be accepted; this is used to defy ip
1228 * spoofing attacks. Note that this only works against somebody
1229 * doing IP spoofing from a remote machine; any machine on the local
1230 * network can still see outgoing packets and catch the random
1231 * cookie. This only affects rhosts authentication, and this is one
1232 * of the reasons why it is inherently insecure.
1234 for (i = 0; i < 8; i++) {
1236 rand = arc4random();
1237 cookie[i] = rand & 0xff;
1242 * Send our public key. We include in the packet 64 bits of random
1243 * data that must be matched in the reply in order to prevent IP
1246 packet_start(SSH_SMSG_PUBLIC_KEY);
1247 for (i = 0; i < 8; i++)
1248 packet_put_char(cookie[i]);
1250 /* Store our public server RSA key. */
1251 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1252 packet_put_bignum(sensitive_data.server_key->rsa->e);
1253 packet_put_bignum(sensitive_data.server_key->rsa->n);
1255 /* Store our public host RSA key. */
1256 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1257 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1258 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1260 /* Put protocol flags. */
1261 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1263 /* Declare which ciphers we support. */
1264 packet_put_int(cipher_mask_ssh1(0));
1266 /* Declare supported authentication types. */
1268 if (options.rhosts_authentication)
1269 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1270 if (options.rhosts_rsa_authentication)
1271 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1272 if (options.rsa_authentication)
1273 auth_mask |= 1 << SSH_AUTH_RSA;
1275 if (options.kerberos_authentication)
1276 auth_mask |= 1 << SSH_AUTH_KERBEROS;
1279 if (options.kerberos_tgt_passing)
1280 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1281 if (options.afs_token_passing)
1282 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1284 if (options.challenge_reponse_authentication == 1)
1285 auth_mask |= 1 << SSH_AUTH_TIS;
1286 if (options.password_authentication)
1287 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1288 packet_put_int(auth_mask);
1290 /* Send the packet and wait for it to be sent. */
1292 packet_write_wait();
1294 debug("Sent %d bit server key and %d bit host key.",
1295 BN_num_bits(sensitive_data.server_key->rsa->n),
1296 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1298 /* Read clients reply (cipher type and session key). */
1299 packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
1301 /* Get cipher type and check whether we accept this. */
1302 cipher_type = packet_get_char();
1304 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1305 packet_disconnect("Warning: client selects unsupported cipher.");
1307 /* Get check bytes from the packet. These must match those we
1308 sent earlier with the public key packet. */
1309 for (i = 0; i < 8; i++)
1310 if (cookie[i] != packet_get_char())
1311 packet_disconnect("IP Spoofing check bytes do not match.");
1313 debug("Encryption type: %.200s", cipher_name(cipher_type));
1315 /* Get the encrypted integer. */
1316 session_key_int = BN_new();
1317 packet_get_bignum(session_key_int, &slen);
1319 protocol_flags = packet_get_int();
1320 packet_set_protocol_flags(protocol_flags);
1322 packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
1325 * Decrypt it using our private server key and private host key (key
1326 * with larger modulus first).
1328 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1329 /* Server key has bigger modulus. */
1330 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1331 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1332 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1333 get_remote_ipaddr(),
1334 BN_num_bits(sensitive_data.server_key->rsa->n),
1335 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1336 SSH_KEY_BITS_RESERVED);
1338 if (rsa_private_decrypt(session_key_int, session_key_int,
1339 sensitive_data.server_key->rsa) <= 0)
1341 if (rsa_private_decrypt(session_key_int, session_key_int,
1342 sensitive_data.ssh1_host_key->rsa) <= 0)
1345 /* Host key has bigger modulus (or they are equal). */
1346 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1347 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1348 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1349 get_remote_ipaddr(),
1350 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1351 BN_num_bits(sensitive_data.server_key->rsa->n),
1352 SSH_KEY_BITS_RESERVED);
1354 if (rsa_private_decrypt(session_key_int, session_key_int,
1355 sensitive_data.ssh1_host_key->rsa) < 0)
1357 if (rsa_private_decrypt(session_key_int, session_key_int,
1358 sensitive_data.server_key->rsa) < 0)
1362 * Extract session key from the decrypted integer. The key is in the
1363 * least significant 256 bits of the integer; the first byte of the
1364 * key is in the highest bits.
1367 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1368 len = BN_num_bytes(session_key_int);
1369 if (len < 0 || len > sizeof(session_key)) {
1370 error("do_connection: bad session key len from %s: "
1371 "session_key_int %d > sizeof(session_key) %lu",
1372 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1375 memset(session_key, 0, sizeof(session_key));
1376 BN_bn2bin(session_key_int,
1377 session_key + sizeof(session_key) - len);
1379 compute_session_id(session_id, cookie,
1380 sensitive_data.ssh1_host_key->rsa->n,
1381 sensitive_data.server_key->rsa->n);
1383 * Xor the first 16 bytes of the session key with the
1386 for (i = 0; i < 16; i++)
1387 session_key[i] ^= session_id[i];
1391 int bytes = BN_num_bytes(session_key_int);
1392 char *buf = xmalloc(bytes);
1395 log("do_connection: generating a fake encryption key");
1396 BN_bn2bin(session_key_int, buf);
1398 MD5_Update(&md, buf, bytes);
1399 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1400 MD5_Final(session_key, &md);
1402 MD5_Update(&md, session_key, 16);
1403 MD5_Update(&md, buf, bytes);
1404 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1405 MD5_Final(session_key + 16, &md);
1406 memset(buf, 0, bytes);
1408 for (i = 0; i < 16; i++)
1409 session_id[i] = session_key[i] ^ session_key[i + 16];
1411 /* Destroy the private and public keys. They will no longer be needed. */
1412 destroy_sensitive_data();
1414 /* Destroy the decrypted integer. It is no longer needed. */
1415 BN_clear_free(session_key_int);
1417 /* Set the session key. From this on all communications will be encrypted. */
1418 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1420 /* Destroy our copy of the session key. It is no longer needed. */
1421 memset(session_key, 0, sizeof(session_key));
1423 debug("Received session key; encryption turned on.");
1425 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1426 packet_start(SSH_SMSG_SUCCESS);
1428 packet_write_wait();
1432 * SSH2 key exchange: diffie-hellman-group1-sha1
1437 Buffer *server_kexinit;
1438 Buffer *client_kexinit;
1442 char *cprop[PROPOSAL_MAX];
1446 if (options.ciphers != NULL) {
1447 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1448 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1450 if (options.macs != NULL) {
1451 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1452 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1454 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1456 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1457 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1459 server_kexinit = kex_init(myproposal);
1460 client_kexinit = xmalloc(sizeof(*client_kexinit));
1461 buffer_init(client_kexinit);
1463 /* algorithm negotiation */
1464 kex_exchange_kexinit(server_kexinit, client_kexinit, cprop);
1465 kex = kex_choose_conf(cprop, myproposal, 1);
1466 for (i = 0; i < PROPOSAL_MAX; i++)
1469 switch (kex->kex_type) {
1471 ssh_dh1_server(kex, client_kexinit, server_kexinit);
1474 ssh_dhgex_server(kex, client_kexinit, server_kexinit);
1477 fatal("Unsupported key exchange %d", kex->kex_type);
1480 debug("send SSH2_MSG_NEWKEYS.");
1481 packet_start(SSH2_MSG_NEWKEYS);
1483 packet_write_wait();
1484 debug("done: send SSH2_MSG_NEWKEYS.");
1486 debug("Wait SSH2_MSG_NEWKEYS.");
1487 packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1488 debug("GOT SSH2_MSG_NEWKEYS.");
1491 /* send 1st encrypted/maced/compressed message */
1492 packet_start(SSH2_MSG_IGNORE);
1493 packet_put_cstring("markus");
1495 packet_write_wait();
1498 debug("done: KEX2.");
1505 /* diffie-hellman-group1-sha1 */
1508 ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1513 int payload_len, dlen;
1515 u_char *signature = NULL;
1516 u_char *server_host_key_blob = NULL;
1521 BIGNUM *shared_secret = 0;
1523 BIGNUM *dh_client_pub = 0;
1526 hostkey = get_hostkey_by_type(kex->hostkey_type);
1527 if (hostkey == NULL)
1528 fatal("Unsupported hostkey type %d", kex->hostkey_type);
1531 /* generate DH key */
1532 dh = dh_new_group1(); /* XXX depends on 'kex' */
1533 dh_gen_key(dh, kex->we_need * 8);
1535 debug("Wait SSH2_MSG_KEXDH_INIT.");
1536 packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
1539 dh_client_pub = BN_new();
1540 if (dh_client_pub == NULL)
1541 fatal("dh_client_pub == NULL");
1542 packet_get_bignum2(dh_client_pub, &dlen);
1545 fprintf(stderr, "\ndh_client_pub= ");
1546 BN_print_fp(stderr, dh_client_pub);
1547 fprintf(stderr, "\n");
1548 debug("bits %d", BN_num_bits(dh_client_pub));
1552 fprintf(stderr, "\np= ");
1553 BN_print_fp(stderr, dh->p);
1554 fprintf(stderr, "\ng= ");
1556 fprintf(stderr, "\npub= ");
1557 BN_print_fp(stderr, dh->pub_key);
1558 fprintf(stderr, "\n");
1559 DHparams_print_fp(stderr, dh);
1561 if (!dh_pub_is_valid(dh, dh_client_pub))
1562 packet_disconnect("bad client public DH value");
1565 kbuf = xmalloc(klen);
1566 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1569 debug("shared secret: len %d/%d", klen, kout);
1570 fprintf(stderr, "shared secret == ");
1571 for (i = 0; i< kout; i++)
1572 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1573 fprintf(stderr, "\n");
1575 shared_secret = BN_new();
1577 BN_bin2bn(kbuf, kout, shared_secret);
1578 memset(kbuf, 0, klen);
1581 /* XXX precompute? */
1582 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1584 /* calc H */ /* XXX depends on 'kex' */
1586 client_version_string,
1587 server_version_string,
1588 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1589 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1590 (char *)server_host_key_blob, sbloblen,
1595 buffer_free(client_kexinit);
1596 buffer_free(server_kexinit);
1597 xfree(client_kexinit);
1598 xfree(server_kexinit);
1599 BN_free(dh_client_pub);
1601 fprintf(stderr, "hash == ");
1602 for (i = 0; i< 20; i++)
1603 fprintf(stderr, "%02x", (hash[i])&0xff);
1604 fprintf(stderr, "\n");
1606 /* save session id := H */
1607 /* XXX hashlen depends on KEX */
1608 session_id2_len = 20;
1609 session_id2 = xmalloc(session_id2_len);
1610 memcpy(session_id2, hash, session_id2_len);
1613 /* XXX hashlen depends on KEX */
1614 key_sign(hostkey, &signature, &slen, hash, 20);
1616 destroy_sensitive_data();
1618 /* send server hostkey, DH pubkey 'f' and singed H */
1619 packet_start(SSH2_MSG_KEXDH_REPLY);
1620 packet_put_string((char *)server_host_key_blob, sbloblen);
1621 packet_put_bignum2(dh->pub_key); /* f */
1622 packet_put_string((char *)signature, slen);
1625 xfree(server_host_key_blob);
1626 packet_write_wait();
1628 kex_derive_keys(kex, hash, shared_secret);
1629 BN_clear_free(shared_secret);
1630 packet_set_kex(kex);
1632 /* have keys, free DH */
1636 /* diffie-hellman-group-exchange-sha1 */
1639 ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1644 int payload_len, dlen;
1646 u_char *signature = NULL;
1647 u_char *server_host_key_blob = NULL;
1652 BIGNUM *shared_secret = 0;
1654 BIGNUM *dh_client_pub = 0;
1657 hostkey = get_hostkey_by_type(kex->hostkey_type);
1658 if (hostkey == NULL)
1659 fatal("Unsupported hostkey type %d", kex->hostkey_type);
1662 debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST.");
1663 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST);
1664 nbits = packet_get_int();
1665 dh = choose_dh(nbits);
1667 debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP.");
1668 packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
1669 packet_put_bignum2(dh->p);
1670 packet_put_bignum2(dh->g);
1672 packet_write_wait();
1674 /* Compute our exchange value in parallel with the client */
1676 dh_gen_key(dh, kex->we_need * 8);
1678 debug("Wait SSH2_MSG_KEX_DH_GEX_INIT.");
1679 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT);
1682 dh_client_pub = BN_new();
1683 if (dh_client_pub == NULL)
1684 fatal("dh_client_pub == NULL");
1685 packet_get_bignum2(dh_client_pub, &dlen);
1688 fprintf(stderr, "\ndh_client_pub= ");
1689 BN_print_fp(stderr, dh_client_pub);
1690 fprintf(stderr, "\n");
1691 debug("bits %d", BN_num_bits(dh_client_pub));
1695 fprintf(stderr, "\np= ");
1696 BN_print_fp(stderr, dh->p);
1697 fprintf(stderr, "\ng= ");
1699 fprintf(stderr, "\npub= ");
1700 BN_print_fp(stderr, dh->pub_key);
1701 fprintf(stderr, "\n");
1702 DHparams_print_fp(stderr, dh);
1704 if (!dh_pub_is_valid(dh, dh_client_pub))
1705 packet_disconnect("bad client public DH value");
1708 kbuf = xmalloc(klen);
1709 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1712 debug("shared secret: len %d/%d", klen, kout);
1713 fprintf(stderr, "shared secret == ");
1714 for (i = 0; i< kout; i++)
1715 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1716 fprintf(stderr, "\n");
1718 shared_secret = BN_new();
1720 BN_bin2bn(kbuf, kout, shared_secret);
1721 memset(kbuf, 0, klen);
1724 /* XXX precompute? */
1725 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1727 /* calc H */ /* XXX depends on 'kex' */
1728 hash = kex_hash_gex(
1729 client_version_string,
1730 server_version_string,
1731 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1732 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1733 (char *)server_host_key_blob, sbloblen,
1734 nbits, dh->p, dh->g,
1739 buffer_free(client_kexinit);
1740 buffer_free(server_kexinit);
1741 xfree(client_kexinit);
1742 xfree(server_kexinit);
1743 BN_free(dh_client_pub);
1745 fprintf(stderr, "hash == ");
1746 for (i = 0; i< 20; i++)
1747 fprintf(stderr, "%02x", (hash[i])&0xff);
1748 fprintf(stderr, "\n");
1750 /* save session id := H */
1751 /* XXX hashlen depends on KEX */
1752 session_id2_len = 20;
1753 session_id2 = xmalloc(session_id2_len);
1754 memcpy(session_id2, hash, session_id2_len);
1757 /* XXX hashlen depends on KEX */
1758 key_sign(hostkey, &signature, &slen, hash, 20);
1760 destroy_sensitive_data();
1762 /* send server hostkey, DH pubkey 'f' and singed H */
1763 packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
1764 packet_put_string((char *)server_host_key_blob, sbloblen);
1765 packet_put_bignum2(dh->pub_key); /* f */
1766 packet_put_string((char *)signature, slen);
1769 xfree(server_host_key_blob);
1770 packet_write_wait();
1772 kex_derive_keys(kex, hash, shared_secret);
1773 BN_clear_free(shared_secret);
1774 packet_set_kex(kex);
1776 /* have keys, free DH */