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Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller95def091999-11-25 00:26:21 +11002 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
Damien Millere4340be2000-09-16 13:29:08 +11005 * This program is the ssh daemon. It listens for connections from clients,
6 * and performs authentication, executes use commands or shell, and forwards
Damien Miller95def091999-11-25 00:26:21 +11007 * information to/from the application to the user client over an encrypted
Damien Millere4340be2000-09-16 13:29:08 +11008 * connection. This can also handle forwarding of X11, TCP/IP, and
9 * authentication agent connections.
Damien Millerefb4afe2000-04-12 18:45:05 +100010 *
Damien Millere4340be2000-09-16 13:29:08 +110011 * 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".
16 *
17 * SSH2 implementation:
18 *
19 * Copyright (c) 2000 Markus Friedl. All rights reserved.
20 *
21 * Redistribution and use in source and binary forms, with or without
22 * modification, are permitted provided that the following conditions
23 * are met:
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.
29 *
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.
Damien Miller95def091999-11-25 00:26:21 +110040 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100041
42#include "includes.h"
Damien Miller27dbe6f2001-03-19 22:36:20 +110043RCSID("$OpenBSD: sshd.c,v 1.175 2001/03/18 23:30:55 deraadt Exp $");
Damien Millerd4a8b7e1999-10-27 13:42:43 +100044
Ben Lindstrom226cfa02001-01-22 05:34:40 +000045#include <openssl/dh.h>
46#include <openssl/bn.h>
47#include <openssl/hmac.h>
48
49#include "ssh.h"
50#include "ssh1.h"
51#include "ssh2.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100052#include "xmalloc.h"
53#include "rsa.h"
Ben Lindstromd95c09c2001-02-18 19:13:33 +000054#include "sshpty.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100055#include "packet.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100056#include "mpaux.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000057#include "log.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100058#include "servconf.h"
59#include "uidswap.h"
60#include "compat.h"
Damien Millerb38eff82000-04-01 11:09:21 +100061#include "buffer.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000062#include "cipher.h"
Damien Millerefb4afe2000-04-12 18:45:05 +100063#include "kex.h"
Damien Millerb38eff82000-04-01 11:09:21 +100064#include "key.h"
Damien Miller874d77b2000-10-14 16:23:11 +110065#include "dh.h"
Damien Millerefb4afe2000-04-12 18:45:05 +100066#include "myproposal.h"
Damien Millereba71ba2000-04-29 23:57:08 +100067#include "authfile.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000068#include "pathnames.h"
69#include "atomicio.h"
70#include "canohost.h"
71#include "auth.h"
72#include "misc.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100073
74#ifdef LIBWRAP
75#include <tcpd.h>
76#include <syslog.h>
77int allow_severity = LOG_INFO;
78int deny_severity = LOG_WARNING;
79#endif /* LIBWRAP */
80
81#ifndef O_NOCTTY
82#define O_NOCTTY 0
83#endif
84
Ben Lindstrom49a79c02000-11-17 03:47:20 +000085#ifdef HAVE___PROGNAME
86extern char *__progname;
87#else
88char *__progname;
89#endif
90
Damien Millerd4a8b7e1999-10-27 13:42:43 +100091/* Server configuration options. */
92ServerOptions options;
93
94/* Name of the server configuration file. */
Ben Lindstrom226cfa02001-01-22 05:34:40 +000095char *config_file_name = _PATH_SERVER_CONFIG_FILE;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100096
Damien Miller4af51302000-04-16 11:18:38 +100097/*
Damien Miller34132e52000-01-14 15:45:46 +110098 * 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.
100 */
Damien Miller7d80e342000-01-19 14:36:49 +1100101#ifdef IPV4_DEFAULT
102int IPv4or6 = AF_INET;
103#else
Damien Miller34132e52000-01-14 15:45:46 +1100104int IPv4or6 = AF_UNSPEC;
Damien Miller7d80e342000-01-19 14:36:49 +1100105#endif
Damien Miller34132e52000-01-14 15:45:46 +1100106
Damien Miller95def091999-11-25 00:26:21 +1100107/*
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.
112 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000113int debug_flag = 0;
114
115/* Flag indicating that the daemon is being started from inetd. */
116int inetd_flag = 0;
117
Ben Lindstromc72745a2000-12-02 19:03:54 +0000118/* Flag indicating that sshd should not detach and become a daemon. */
119int no_daemon_flag = 0;
120
Damien Miller5ce662a1999-11-11 17:57:39 +1100121/* debug goes to stderr unless inetd_flag is set */
122int log_stderr = 0;
123
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000124/* Saved arguments to main(). */
125char **saved_argv;
Damien Millerb8c656e2000-06-28 15:22:41 +1000126int saved_argc;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000127
Damien Miller5428f641999-11-25 11:54:57 +1100128/*
Damien Miller34132e52000-01-14 15:45:46 +1100129 * The sockets that the server is listening; this is used in the SIGHUP
130 * signal handler.
Damien Miller5428f641999-11-25 11:54:57 +1100131 */
Damien Miller34132e52000-01-14 15:45:46 +1100132#define MAX_LISTEN_SOCKS 16
133int listen_socks[MAX_LISTEN_SOCKS];
134int num_listen_socks = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000135
Damien Miller5428f641999-11-25 11:54:57 +1100136/*
137 * the client's version string, passed by sshd2 in compat mode. if != NULL,
138 * sshd will skip the version-number exchange
139 */
Damien Miller95def091999-11-25 00:26:21 +1100140char *client_version_string = NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000141char *server_version_string = NULL;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000142
Damien Miller5428f641999-11-25 11:54:57 +1100143/*
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.
150 */
Damien Miller95def091999-11-25 00:26:21 +1100151struct {
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000152 Key *server_key; /* ephemeral server key */
Damien Miller0bc1bd82000-11-13 22:57:25 +1100153 Key *ssh1_host_key; /* ssh1 host key */
154 Key **host_keys; /* all private host keys */
155 int have_ssh1_key;
156 int have_ssh2_key;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000157 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000158} sensitive_data;
159
Damien Miller5428f641999-11-25 11:54:57 +1100160/*
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000161 * 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.
Damien Miller5428f641999-11-25 11:54:57 +1100163 */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000164int key_do_regen = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000165
166/* This is set to true when SIGHUP is received. */
167int received_sighup = 0;
168
Damien Millerb38eff82000-04-01 11:09:21 +1000169/* session identifier, used by RSA-auth */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000170u_char session_id[16];
Damien Millerb38eff82000-04-01 11:09:21 +1000171
Damien Millereba71ba2000-04-29 23:57:08 +1000172/* same for ssh2 */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000173u_char *session_id2 = NULL;
Damien Millereba71ba2000-04-29 23:57:08 +1000174int session_id2_len = 0;
175
Damien Miller942da032000-08-18 13:59:06 +1000176/* record remote hostname or ip */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000177u_int utmp_len = MAXHOSTNAMELEN;
Damien Miller942da032000-08-18 13:59:06 +1000178
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000179/* Prototypes for various functions defined later in this file. */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000180void do_ssh1_kex(void);
181void do_ssh2_kex(void);
Damien Miller98c7ad62000-03-09 21:27:49 +1100182
Damien Miller874d77b2000-10-14 16:23:11 +1100183void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *);
184void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *);
185
Damien Miller98c7ad62000-03-09 21:27:49 +1100186/*
Damien Miller34132e52000-01-14 15:45:46 +1100187 * Close all listening sockets
188 */
189void
190close_listen_socks(void)
191{
192 int i;
193 for (i = 0; i < num_listen_socks; i++)
194 close(listen_socks[i]);
195 num_listen_socks = -1;
196}
197
198/*
Damien Miller95def091999-11-25 00:26:21 +1100199 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
200 * the effect is to reread the configuration file (and to regenerate
201 * the server key).
202 */
Damien Miller4af51302000-04-16 11:18:38 +1000203void
Damien Miller95def091999-11-25 00:26:21 +1100204sighup_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000205{
Damien Miller95def091999-11-25 00:26:21 +1100206 received_sighup = 1;
207 signal(SIGHUP, sighup_handler);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000208}
209
Damien Miller95def091999-11-25 00:26:21 +1100210/*
211 * Called from the main program after receiving SIGHUP.
212 * Restarts the server.
213 */
Damien Miller4af51302000-04-16 11:18:38 +1000214void
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000215sighup_restart(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000216{
Damien Miller95def091999-11-25 00:26:21 +1100217 log("Received SIGHUP; restarting.");
Damien Miller34132e52000-01-14 15:45:46 +1100218 close_listen_socks();
Damien Miller95def091999-11-25 00:26:21 +1100219 execv(saved_argv[0], saved_argv);
Kevin Stevesec84dc12000-12-13 17:45:15 +0000220 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100221 exit(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000222}
223
Damien Miller95def091999-11-25 00:26:21 +1100224/*
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.
228 */
Damien Miller4af51302000-04-16 11:18:38 +1000229void
Damien Miller95def091999-11-25 00:26:21 +1100230sigterm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000231{
Damien Miller95def091999-11-25 00:26:21 +1100232 log("Received signal %d; terminating.", sig);
Damien Miller34132e52000-01-14 15:45:46 +1100233 close_listen_socks();
Damien Miller6f83b8e2000-05-02 09:23:45 +1000234 unlink(options.pid_file);
Damien Miller95def091999-11-25 00:26:21 +1100235 exit(255);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000236}
237
Damien Miller95def091999-11-25 00:26:21 +1100238/*
239 * SIGCHLD handler. This is called whenever a child dies. This will then
240 * reap any zombies left by exited c.
241 */
Damien Miller4af51302000-04-16 11:18:38 +1000242void
Damien Miller95def091999-11-25 00:26:21 +1100243main_sigchld_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000244{
Damien Miller95def091999-11-25 00:26:21 +1100245 int save_errno = errno;
246 int status;
Damien Miller431f66b1999-11-21 18:31:57 +1100247
Damien Miller95def091999-11-25 00:26:21 +1100248 while (waitpid(-1, &status, WNOHANG) > 0)
249 ;
Damien Miller431f66b1999-11-21 18:31:57 +1100250
Damien Miller95def091999-11-25 00:26:21 +1100251 signal(SIGCHLD, main_sigchld_handler);
252 errno = save_errno;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000253}
254
Damien Miller95def091999-11-25 00:26:21 +1100255/*
256 * Signal handler for the alarm after the login grace period has expired.
257 */
Damien Miller4af51302000-04-16 11:18:38 +1000258void
Damien Miller95def091999-11-25 00:26:21 +1100259grace_alarm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000260{
Damien Miller95def091999-11-25 00:26:21 +1100261 /* Close the connection. */
262 packet_close();
263
264 /* Log error and exit. */
265 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000266}
267
Damien Miller95def091999-11-25 00:26:21 +1100268/*
Damien Miller95def091999-11-25 00:26:21 +1100269 * 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
273 * problems.
274 */
Damien Miller4af51302000-04-16 11:18:38 +1000275void
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000276generate_ephemeral_server_key(void)
Damien Miller0bc1bd82000-11-13 22:57:25 +1100277{
Ben Lindstromeb648a72001-03-05 06:00:29 +0000278 u_int32_t rand = 0;
279 int i;
280
Damien Miller0bc1bd82000-11-13 22:57:25 +1100281 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);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100286 log("RSA key generation complete.");
Ben Lindstromeb648a72001-03-05 06:00:29 +0000287
288 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
289 if (i % 4 == 0)
290 rand = arc4random();
291 sensitive_data.ssh1_cookie[i] = rand & 0xff;
292 rand >>= 8;
293 }
294 arc4random_stir();
Damien Miller0bc1bd82000-11-13 22:57:25 +1100295}
Ben Lindstrom2f959b42001-01-11 06:20:23 +0000296
Damien Miller0bc1bd82000-11-13 22:57:25 +1100297void
Damien Miller95def091999-11-25 00:26:21 +1100298key_regeneration_alarm(int sig)
299{
300 int save_errno = errno;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000301 signal(SIGALRM, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +1100302 errno = save_errno;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000303 key_do_regen = 1;
Damien Miller95def091999-11-25 00:26:21 +1100304}
305
Damien Millerb38eff82000-04-01 11:09:21 +1000306void
307sshd_exchange_identification(int sock_in, int sock_out)
308{
Damien Miller78928792000-04-12 20:17:38 +1000309 int i, mismatch;
Damien Millerb38eff82000-04-01 11:09:21 +1000310 int remote_major, remote_minor;
Damien Miller78928792000-04-12 20:17:38 +1000311 int major, minor;
Damien Millerb38eff82000-04-01 11:09:21 +1000312 char *s;
313 char buf[256]; /* Must not be larger than remote_version. */
314 char remote_version[256]; /* Must be at least as big as buf. */
315
Damien Miller78928792000-04-12 20:17:38 +1000316 if ((options.protocol & SSH_PROTO_1) &&
317 (options.protocol & SSH_PROTO_2)) {
318 major = PROTOCOL_MAJOR_1;
319 minor = 99;
320 } else if (options.protocol & SSH_PROTO_2) {
321 major = PROTOCOL_MAJOR_2;
322 minor = PROTOCOL_MINOR_2;
323 } else {
324 major = PROTOCOL_MAJOR_1;
325 minor = PROTOCOL_MINOR_1;
326 }
327 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
Damien Millerb38eff82000-04-01 11:09:21 +1000328 server_version_string = xstrdup(buf);
329
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());
335 fatal_cleanup();
336 }
337
Ben Lindstrom5393f932001-02-15 03:17:13 +0000338 /* Read other side's version identification. */
339 memset(buf, 0, sizeof(buf));
Damien Millerb38eff82000-04-01 11:09:21 +1000340 for (i = 0; i < sizeof(buf) - 1; i++) {
Damien Millerbf7f4662000-06-23 10:16:38 +1000341 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
Ben Lindstroma9a29e12001-02-20 01:20:47 +0000342 log("Did not receive identification string from %s.",
343 get_remote_ipaddr());
Damien Millerb38eff82000-04-01 11:09:21 +1000344 fatal_cleanup();
345 }
346 if (buf[i] == '\r') {
347 buf[i] = '\n';
348 buf[i + 1] = 0;
Damien Miller874d77b2000-10-14 16:23:11 +1100349 /* Kludge for F-Secure Macintosh < 1.0.2 */
350 if (i == 12 &&
351 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
352 break;
Damien Millerb38eff82000-04-01 11:09:21 +1000353 continue;
Damien Millerb38eff82000-04-01 11:09:21 +1000354 }
355 if (buf[i] == '\n') {
356 /* buf[i] == '\n' */
357 buf[i + 1] = 0;
358 break;
359 }
360 }
361 buf[sizeof(buf) - 1] = 0;
362 client_version_string = xstrdup(buf);
363 }
364
365 /*
366 * Check that the versions match. In future this might accept
367 * several versions and set appropriate flags to handle them.
368 */
369 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
370 &remote_major, &remote_minor, remote_version) != 3) {
Damien Miller4af51302000-04-16 11:18:38 +1000371 s = "Protocol mismatch.\n";
Damien Millerb38eff82000-04-01 11:09:21 +1000372 (void) atomicio(write, sock_out, s, strlen(s));
373 close(sock_in);
374 close(sock_out);
375 log("Bad protocol version identification '%.100s' from %s",
376 client_version_string, get_remote_ipaddr());
377 fatal_cleanup();
378 }
379 debug("Client protocol version %d.%d; client software version %.100s",
380 remote_major, remote_minor, remote_version);
381
Damien Millerefb4afe2000-04-12 18:45:05 +1000382 compat_datafellows(remote_version);
383
Damien Miller27dbe6f2001-03-19 22:36:20 +1100384 if (datafellows & SSH_BUG_SCANNER) {
385 log("scanned from %s with %s. Don't panic.",
386 get_remote_ipaddr(), client_version_string);
387 fatal_cleanup();
388 }
389
Damien Miller78928792000-04-12 20:17:38 +1000390 mismatch = 0;
Damien Millerb38eff82000-04-01 11:09:21 +1000391 switch(remote_major) {
392 case 1:
Damien Millereba71ba2000-04-29 23:57:08 +1000393 if (remote_minor == 99) {
394 if (options.protocol & SSH_PROTO_2)
395 enable_compat20();
396 else
397 mismatch = 1;
398 break;
399 }
Damien Miller78928792000-04-12 20:17:38 +1000400 if (!(options.protocol & SSH_PROTO_1)) {
401 mismatch = 1;
402 break;
403 }
Damien Millerb38eff82000-04-01 11:09:21 +1000404 if (remote_minor < 3) {
Damien Miller37023962000-07-11 17:31:38 +1000405 packet_disconnect("Your ssh version is too old and "
Damien Millerb38eff82000-04-01 11:09:21 +1000406 "is no longer supported. Please install a newer version.");
407 } else if (remote_minor == 3) {
408 /* note that this disables agent-forwarding */
409 enable_compat13();
410 }
Damien Miller78928792000-04-12 20:17:38 +1000411 break;
Damien Millerefb4afe2000-04-12 18:45:05 +1000412 case 2:
Damien Miller78928792000-04-12 20:17:38 +1000413 if (options.protocol & SSH_PROTO_2) {
Damien Millerefb4afe2000-04-12 18:45:05 +1000414 enable_compat20();
415 break;
416 }
417 /* FALLTHROUGH */
Damien Miller4af51302000-04-16 11:18:38 +1000418 default:
Damien Miller78928792000-04-12 20:17:38 +1000419 mismatch = 1;
Damien Millerb38eff82000-04-01 11:09:21 +1000420 break;
421 }
Damien Millerefb4afe2000-04-12 18:45:05 +1000422 chop(server_version_string);
423 chop(client_version_string);
Damien Miller78928792000-04-12 20:17:38 +1000424 debug("Local version string %.200s", server_version_string);
425
426 if (mismatch) {
427 s = "Protocol major versions differ.\n";
428 (void) atomicio(write, sock_out, s, strlen(s));
429 close(sock_in);
430 close(sock_out);
431 log("Protocol major versions differ for %s: %.200s vs. %.200s",
432 get_remote_ipaddr(),
433 server_version_string, client_version_string);
434 fatal_cleanup();
435 }
Damien Millereba71ba2000-04-29 23:57:08 +1000436 if (compat20)
437 packet_set_ssh2_format();
438}
439
440
Damien Miller0bc1bd82000-11-13 22:57:25 +1100441/* Destroy the host and server keys. They will no longer be needed. */
Damien Millereba71ba2000-04-29 23:57:08 +1000442void
443destroy_sensitive_data(void)
444{
Damien Miller0bc1bd82000-11-13 22:57:25 +1100445 int i;
446
447 if (sensitive_data.server_key) {
448 key_free(sensitive_data.server_key);
449 sensitive_data.server_key = NULL;
450 }
Kevin Stevesef4eea92001-02-05 12:42:17 +0000451 for(i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100452 if (sensitive_data.host_keys[i]) {
453 key_free(sensitive_data.host_keys[i]);
454 sensitive_data.host_keys[i] = NULL;
455 }
456 }
457 sensitive_data.ssh1_host_key = NULL;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000458 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100459}
460Key *
461load_private_key_autodetect(const char *filename)
462{
463 struct stat st;
464 int type;
465 Key *public, *private;
466
467 if (stat(filename, &st) < 0) {
468 perror(filename);
469 return NULL;
470 }
471 /*
472 * try to load the public key. right now this only works for RSA1,
473 * since SSH2 keys are fully encrypted
474 */
475 type = KEY_RSA1;
476 public = key_new(type);
477 if (!load_public_key(filename, public, NULL)) {
478 /* ok, so we will assume this is 'some' key */
479 type = KEY_UNSPEC;
480 }
481 key_free(public);
482
483 /* Ok, try key with empty passphrase */
484 private = key_new(type);
485 if (load_private_key(filename, "", private, NULL)) {
486 debug("load_private_key_autodetect: type %d %s",
487 private->type, key_type(private));
488 return private;
489 }
490 key_free(private);
491 return NULL;
492}
493
494char *
495list_hostkey_types(void)
496{
497 static char buf[1024];
498 int i;
499 buf[0] = '\0';
500 for(i = 0; i < options.num_host_key_files; i++) {
501 Key *key = sensitive_data.host_keys[i];
502 if (key == NULL)
503 continue;
504 switch(key->type) {
505 case KEY_RSA:
506 case KEY_DSA:
507 strlcat(buf, key_ssh_name(key), sizeof buf);
508 strlcat(buf, ",", sizeof buf);
509 break;
510 }
511 }
512 i = strlen(buf);
513 if (i > 0 && buf[i-1] == ',')
514 buf[i-1] = '\0';
515 debug("list_hostkey_types: %s", buf);
516 return buf;
517}
518
519Key *
520get_hostkey_by_type(int type)
521{
522 int i;
523 for(i = 0; i < options.num_host_key_files; i++) {
524 Key *key = sensitive_data.host_keys[i];
525 if (key != NULL && key->type == type)
526 return key;
527 }
528 return NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000529}
530
Damien Miller942da032000-08-18 13:59:06 +1000531/*
532 * returns 1 if connection should be dropped, 0 otherwise.
533 * dropping starts at connection #max_startups_begin with a probability
534 * of (max_startups_rate/100). the probability increases linearly until
535 * all connections are dropped for startups > max_startups
536 */
537int
538drop_connection(int startups)
539{
540 double p, r;
541
542 if (startups < options.max_startups_begin)
543 return 0;
544 if (startups >= options.max_startups)
545 return 1;
546 if (options.max_startups_rate == 100)
547 return 1;
548
549 p = 100 - options.max_startups_rate;
550 p *= startups - options.max_startups_begin;
551 p /= (double) (options.max_startups - options.max_startups_begin);
552 p += options.max_startups_rate;
553 p /= 100.0;
554 r = arc4random() / (double) UINT_MAX;
555
556 debug("drop_connection: p %g, r %g", p, r);
557 return (r < p) ? 1 : 0;
558}
559
Damien Miller37023962000-07-11 17:31:38 +1000560int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
561int startup_pipe; /* in child */
562
Damien Miller95def091999-11-25 00:26:21 +1100563/*
564 * Main program for the daemon.
565 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000566int
567main(int ac, char **av)
568{
Damien Miller95def091999-11-25 00:26:21 +1100569 extern char *optarg;
570 extern int optind;
Damien Miller37023962000-07-11 17:31:38 +1000571 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
Damien Miller166fca82000-04-20 07:42:21 +1000572 pid_t pid;
Damien Miller34132e52000-01-14 15:45:46 +1100573 socklen_t fromlen;
Damien Miller34132e52000-01-14 15:45:46 +1100574 fd_set *fdset;
575 struct sockaddr_storage from;
Damien Miller95def091999-11-25 00:26:21 +1100576 const char *remote_ip;
577 int remote_port;
Damien Miller95def091999-11-25 00:26:21 +1100578 FILE *f;
579 struct linger linger;
Damien Miller34132e52000-01-14 15:45:46 +1100580 struct addrinfo *ai;
581 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
582 int listen_sock, maxfd;
Damien Miller37023962000-07-11 17:31:38 +1000583 int startup_p[2];
584 int startups = 0;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000585 int ret, key_used = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000586
Ben Lindstrom49a79c02000-11-17 03:47:20 +0000587 __progname = get_progname(av[0]);
Damien Millerf9b625c2000-07-09 22:42:32 +1000588 init_rng();
589
Kevin Stevesec84dc12000-12-13 17:45:15 +0000590 /* Save argv. */
Damien Millerb8c656e2000-06-28 15:22:41 +1000591 saved_argc = ac;
Damien Miller95def091999-11-25 00:26:21 +1100592 saved_argv = av;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000593
Damien Miller95def091999-11-25 00:26:21 +1100594 /* Initialize configuration options to their default values. */
595 initialize_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000596
Damien Miller95def091999-11-25 00:26:21 +1100597 /* Parse command-line arguments. */
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000598 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDiqQ46")) != -1) {
Damien Miller95def091999-11-25 00:26:21 +1100599 switch (opt) {
Damien Miller34132e52000-01-14 15:45:46 +1100600 case '4':
601 IPv4or6 = AF_INET;
602 break;
603 case '6':
604 IPv4or6 = AF_INET6;
605 break;
Damien Miller95def091999-11-25 00:26:21 +1100606 case 'f':
607 config_file_name = optarg;
608 break;
609 case 'd':
Damien Millere4340be2000-09-16 13:29:08 +1100610 if (0 == debug_flag) {
611 debug_flag = 1;
612 options.log_level = SYSLOG_LEVEL_DEBUG1;
613 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
614 options.log_level++;
615 } else {
616 fprintf(stderr, "Too high debugging level.\n");
617 exit(1);
618 }
Damien Miller95def091999-11-25 00:26:21 +1100619 break;
Ben Lindstromc72745a2000-12-02 19:03:54 +0000620 case 'D':
621 no_daemon_flag = 1;
622 break;
Damien Miller95def091999-11-25 00:26:21 +1100623 case 'i':
624 inetd_flag = 1;
625 break;
626 case 'Q':
Ben Lindstromd5390202001-01-29 08:07:43 +0000627 /* ignored */
Damien Miller95def091999-11-25 00:26:21 +1100628 break;
629 case 'q':
630 options.log_level = SYSLOG_LEVEL_QUIET;
631 break;
632 case 'b':
633 options.server_key_bits = atoi(optarg);
634 break;
635 case 'p':
Damien Miller34132e52000-01-14 15:45:46 +1100636 options.ports_from_cmdline = 1;
Damien Millere4340be2000-09-16 13:29:08 +1100637 if (options.num_ports >= MAX_PORTS) {
638 fprintf(stderr, "too many ports.\n");
639 exit(1);
640 }
Damien Miller34132e52000-01-14 15:45:46 +1100641 options.ports[options.num_ports++] = atoi(optarg);
Damien Miller95def091999-11-25 00:26:21 +1100642 break;
643 case 'g':
644 options.login_grace_time = atoi(optarg);
645 break;
646 case 'k':
647 options.key_regeneration_time = atoi(optarg);
648 break;
649 case 'h':
Damien Miller0bc1bd82000-11-13 22:57:25 +1100650 if (options.num_host_key_files >= MAX_HOSTKEYS) {
651 fprintf(stderr, "too many host keys.\n");
652 exit(1);
653 }
654 options.host_key_files[options.num_host_key_files++] = optarg;
Damien Miller95def091999-11-25 00:26:21 +1100655 break;
656 case 'V':
657 client_version_string = optarg;
658 /* only makes sense with inetd_flag, i.e. no listen() */
659 inetd_flag = 1;
660 break;
Damien Miller942da032000-08-18 13:59:06 +1000661 case 'u':
662 utmp_len = atoi(optarg);
663 break;
Damien Miller95def091999-11-25 00:26:21 +1100664 case '?':
665 default:
666 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
Kevin Stevesec84dc12000-12-13 17:45:15 +0000667 fprintf(stderr, "Usage: %s [options]\n", __progname);
Damien Miller95def091999-11-25 00:26:21 +1100668 fprintf(stderr, "Options:\n");
Ben Lindstrom226cfa02001-01-22 05:34:40 +0000669 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
Damien Millere4340be2000-09-16 13:29:08 +1100670 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
Damien Miller95def091999-11-25 00:26:21 +1100671 fprintf(stderr, " -i Started from inetd\n");
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000672 fprintf(stderr, " -D Do not fork into daemon mode\n");
Damien Miller95def091999-11-25 00:26:21 +1100673 fprintf(stderr, " -q Quiet (no logging)\n");
674 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
675 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
Ben Lindstromd26dcf32001-01-06 15:18:16 +0000676 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
Damien Miller95def091999-11-25 00:26:21 +1100677 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
678 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
Ben Lindstrom226cfa02001-01-22 05:34:40 +0000679 _PATH_HOST_KEY_FILE);
Damien Miller942da032000-08-18 13:59:06 +1000680 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
Damien Miller34132e52000-01-14 15:45:46 +1100681 fprintf(stderr, " -4 Use IPv4 only\n");
682 fprintf(stderr, " -6 Use IPv6 only\n");
Damien Miller95def091999-11-25 00:26:21 +1100683 exit(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000684 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000685 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000686
Damien Miller34132e52000-01-14 15:45:46 +1100687 /*
688 * Force logging to stderr until we have loaded the private host
689 * key (unless started from inetd)
690 */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000691 log_init(__progname,
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000692 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
Damien Miller34132e52000-01-14 15:45:46 +1100693 options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
Ben Lindstromd5390202001-01-29 08:07:43 +0000694 !inetd_flag);
Damien Miller34132e52000-01-14 15:45:46 +1100695
Damien Miller60bc5172001-03-19 09:38:15 +1100696 seed_rng();
697
Damien Miller95def091999-11-25 00:26:21 +1100698 /* Read server configuration options from the configuration file. */
699 read_server_config(&options, config_file_name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000700
Damien Miller95def091999-11-25 00:26:21 +1100701 /* Fill in default values for those options not explicitly set. */
702 fill_default_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000703
Damien Miller95def091999-11-25 00:26:21 +1100704 /* Check that there are no remaining arguments. */
705 if (optind < ac) {
706 fprintf(stderr, "Extra argument %s.\n", av[optind]);
707 exit(1);
708 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000709
Damien Miller95def091999-11-25 00:26:21 +1100710 debug("sshd version %.100s", SSH_VERSION);
Damien Miller2ccf6611999-11-15 15:25:10 +1100711
Damien Miller0bc1bd82000-11-13 22:57:25 +1100712 /* load private host keys */
713 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
Ben Lindstrom46c16222000-12-22 01:43:59 +0000714 for(i = 0; i < options.num_host_key_files; i++)
715 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100716 sensitive_data.server_key = NULL;
717 sensitive_data.ssh1_host_key = NULL;
718 sensitive_data.have_ssh1_key = 0;
719 sensitive_data.have_ssh2_key = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000720
Damien Miller0bc1bd82000-11-13 22:57:25 +1100721 for(i = 0; i < options.num_host_key_files; i++) {
722 Key *key = load_private_key_autodetect(options.host_key_files[i]);
723 if (key == NULL) {
724 error("Could not load host key: %.200s: %.100s",
725 options.host_key_files[i], strerror(errno));
726 continue;
727 }
728 switch(key->type){
729 case KEY_RSA1:
730 sensitive_data.ssh1_host_key = key;
731 sensitive_data.have_ssh1_key = 1;
732 break;
733 case KEY_RSA:
734 case KEY_DSA:
735 sensitive_data.have_ssh2_key = 1;
736 break;
737 }
738 sensitive_data.host_keys[i] = key;
739 }
740 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
741 log("Disabling protocol version 1. Could not load host key");
Damien Millereba71ba2000-04-29 23:57:08 +1000742 options.protocol &= ~SSH_PROTO_1;
743 }
Damien Miller0bc1bd82000-11-13 22:57:25 +1100744 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
745 log("Disabling protocol version 2. Could not load host key");
746 options.protocol &= ~SSH_PROTO_2;
Damien Millereba71ba2000-04-29 23:57:08 +1000747 }
Kevin Stevesadf74cd2001-02-05 14:22:50 +0000748 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
Ben Lindstrom6df8ef42001-03-05 07:47:23 +0000749 log("sshd: no hostkeys available -- exiting.");
Damien Miller95def091999-11-25 00:26:21 +1100750 exit(1);
751 }
Damien Miller95def091999-11-25 00:26:21 +1100752
Damien Millereba71ba2000-04-29 23:57:08 +1000753 /* Check certain values for sanity. */
754 if (options.protocol & SSH_PROTO_1) {
755 if (options.server_key_bits < 512 ||
756 options.server_key_bits > 32768) {
757 fprintf(stderr, "Bad server key size.\n");
758 exit(1);
759 }
760 /*
761 * Check that server and host key lengths differ sufficiently. This
762 * is necessary to make double encryption work with rsaref. Oh, I
763 * hate software patents. I dont know if this can go? Niels
764 */
765 if (options.server_key_bits >
Damien Miller0bc1bd82000-11-13 22:57:25 +1100766 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
Damien Millereba71ba2000-04-29 23:57:08 +1000767 options.server_key_bits <
Damien Miller0bc1bd82000-11-13 22:57:25 +1100768 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
Damien Millereba71ba2000-04-29 23:57:08 +1000769 options.server_key_bits =
Damien Miller0bc1bd82000-11-13 22:57:25 +1100770 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
Damien Millereba71ba2000-04-29 23:57:08 +1000771 debug("Forcing server key to %d bits to make it differ from host key.",
772 options.server_key_bits);
773 }
774 }
775
Damien Miller78315eb2000-09-29 23:01:36 +1100776#ifdef HAVE_SCO_PROTECTED_PW
777 (void) set_auth_parameters(ac, av);
778#endif
779
Damien Millereba71ba2000-04-29 23:57:08 +1000780 /* Initialize the log (it is reinitialized below in case we forked). */
Damien Miller95def091999-11-25 00:26:21 +1100781 if (debug_flag && !inetd_flag)
782 log_stderr = 1;
Kevin Stevesec84dc12000-12-13 17:45:15 +0000783 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +1100784
Damien Millereba71ba2000-04-29 23:57:08 +1000785 /*
786 * If not in debugging mode, and not started from inetd, disconnect
787 * from the controlling terminal, and fork. The original process
788 * exits.
789 */
Ben Lindstromc72745a2000-12-02 19:03:54 +0000790 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
Damien Miller95def091999-11-25 00:26:21 +1100791#ifdef TIOCNOTTY
792 int fd;
793#endif /* TIOCNOTTY */
794 if (daemon(0, 0) < 0)
795 fatal("daemon() failed: %.200s", strerror(errno));
796
797 /* Disconnect from the controlling tty. */
798#ifdef TIOCNOTTY
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000799 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
Damien Miller95def091999-11-25 00:26:21 +1100800 if (fd >= 0) {
801 (void) ioctl(fd, TIOCNOTTY, NULL);
802 close(fd);
803 }
804#endif /* TIOCNOTTY */
805 }
806 /* Reinitialize the log (because of the fork above). */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000807 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +1100808
Damien Miller95def091999-11-25 00:26:21 +1100809 /* Initialize the random number generator. */
810 arc4random_stir();
811
812 /* Chdir to the root directory so that the current disk can be
813 unmounted if desired. */
814 chdir("/");
815
Damien Miller95def091999-11-25 00:26:21 +1100816 /* Start listening for a socket, unless started from inetd. */
817 if (inetd_flag) {
818 int s1, s2;
819 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
820 s2 = dup(s1);
821 sock_in = dup(0);
822 sock_out = dup(1);
Damien Miller994cf142000-07-21 10:19:44 +1000823 startup_pipe = -1;
Damien Millereba71ba2000-04-29 23:57:08 +1000824 /*
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.
828 */
Damien Miller95def091999-11-25 00:26:21 +1100829 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100830 if (options.protocol & SSH_PROTO_1)
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000831 generate_ephemeral_server_key();
Damien Miller95def091999-11-25 00:26:21 +1100832 } else {
Damien Miller34132e52000-01-14 15:45:46 +1100833 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
834 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
835 continue;
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");
843 continue;
844 }
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));
850 continue;
851 }
852 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
853 error("listen_sock O_NONBLOCK: %s", strerror(errno));
854 close(listen_sock);
855 continue;
856 }
857 /*
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
861 * close.
862 */
863 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
864 (void *) &on, sizeof(on));
865 linger.l_onoff = 1;
866 linger.l_linger = 5;
867 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
868 (void *) &linger, sizeof(linger));
Damien Miller95def091999-11-25 00:26:21 +1100869
Damien Miller34132e52000-01-14 15:45:46 +1100870 debug("Bind to port %s on %s.", strport, ntop);
Damien Miller95def091999-11-25 00:26:21 +1100871
Damien Miller34132e52000-01-14 15:45:46 +1100872 /* Bind the socket to the desired port. */
Damien Miller0a4e27d2001-02-18 12:36:39 +1100873 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
874 if (!ai->ai_next)
875 error("Bind to port %s on %s failed: %.200s.",
876 strport, ntop, strerror(errno));
Damien Miller34132e52000-01-14 15:45:46 +1100877 close(listen_sock);
878 continue;
879 }
880 listen_socks[num_listen_socks] = listen_sock;
881 num_listen_socks++;
Damien Miller95def091999-11-25 00:26:21 +1100882
Damien Miller34132e52000-01-14 15:45:46 +1100883 /* 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));
887
Damien Miller95def091999-11-25 00:26:21 +1100888 }
Damien Miller34132e52000-01-14 15:45:46 +1100889 freeaddrinfo(options.listen_addrs);
890
891 if (!num_listen_socks)
892 fatal("Cannot bind any address.");
893
Damien Miller95def091999-11-25 00:26:21 +1100894 if (!debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +1100895 /*
Ben Lindstrom7ad97102000-12-06 01:42:49 +0000896 * 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
Damien Miller5428f641999-11-25 11:54:57 +1100899 * fail if there already is a daemon, and this will
900 * overwrite any old pid in the file.
901 */
Damien Millerbac2d8a2000-09-05 16:13:06 +1100902 f = fopen(options.pid_file, "wb");
Damien Miller95def091999-11-25 00:26:21 +1100903 if (f) {
Ben Lindstrom46c16222000-12-22 01:43:59 +0000904 fprintf(f, "%u\n", (u_int) getpid());
Damien Miller95def091999-11-25 00:26:21 +1100905 fclose(f);
906 }
907 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000908 if (options.protocol & SSH_PROTO_1)
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000909 generate_ephemeral_server_key();
Damien Miller95def091999-11-25 00:26:21 +1100910
Damien Miller95def091999-11-25 00:26:21 +1100911 /* Arrange to restart on SIGHUP. The handler needs listen_sock. */
912 signal(SIGHUP, sighup_handler);
Damien Miller37023962000-07-11 17:31:38 +1000913
Damien Miller95def091999-11-25 00:26:21 +1100914 signal(SIGTERM, sigterm_handler);
915 signal(SIGQUIT, sigterm_handler);
916
917 /* Arrange SIGCHLD to be caught. */
918 signal(SIGCHLD, main_sigchld_handler);
919
Damien Miller34132e52000-01-14 15:45:46 +1100920 /* setup fd set for listen */
Damien Miller37023962000-07-11 17:31:38 +1000921 fdset = NULL;
Damien Miller34132e52000-01-14 15:45:46 +1100922 maxfd = 0;
923 for (i = 0; i < num_listen_socks; i++)
924 if (listen_socks[i] > maxfd)
925 maxfd = listen_socks[i];
Damien Miller37023962000-07-11 17:31:38 +1000926 /* 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;
Damien Miller34132e52000-01-14 15:45:46 +1100930
Damien Miller5428f641999-11-25 11:54:57 +1100931 /*
932 * Stay listening for connections until the system crashes or
933 * the daemon is killed with a signal.
934 */
Damien Miller95def091999-11-25 00:26:21 +1100935 for (;;) {
936 if (received_sighup)
937 sighup_restart();
Damien Miller37023962000-07-11 17:31:38 +1000938 if (fdset != NULL)
939 xfree(fdset);
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000940 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
Damien Miller37023962000-07-11 17:31:38 +1000941 fdset = (fd_set *)xmalloc(fdsetsz);
Damien Miller34132e52000-01-14 15:45:46 +1100942 memset(fdset, 0, fdsetsz);
Damien Miller37023962000-07-11 17:31:38 +1000943
Damien Miller34132e52000-01-14 15:45:46 +1100944 for (i = 0; i < num_listen_socks; i++)
945 FD_SET(listen_socks[i], fdset);
Damien Miller37023962000-07-11 17:31:38 +1000946 for (i = 0; i < options.max_startups; i++)
947 if (startup_pipes[i] != -1)
948 FD_SET(startup_pipes[i], fdset);
949
950 /* Wait in select until there is a connection. */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000951 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) {
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000955 generate_ephemeral_server_key();
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000956 key_used = 0;
957 key_do_regen = 0;
Damien Miller34132e52000-01-14 15:45:46 +1100958 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000959 if (ret < 0)
960 continue;
961
Damien Miller37023962000-07-11 17:31:38 +1000962 for (i = 0; i < options.max_startups; i++)
963 if (startup_pipes[i] != -1 &&
964 FD_ISSET(startup_pipes[i], fdset)) {
965 /*
966 * the read end of the pipe is ready
967 * if the child has closed the pipe
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000968 * after successful authentication
Damien Miller37023962000-07-11 17:31:38 +1000969 * or if the child has died
970 */
971 close(startup_pipes[i]);
972 startup_pipes[i] = -1;
973 startups--;
974 }
Damien Miller34132e52000-01-14 15:45:46 +1100975 for (i = 0; i < num_listen_socks; i++) {
976 if (!FD_ISSET(listen_socks[i], fdset))
Damien Miller95def091999-11-25 00:26:21 +1100977 continue;
Damien Miller37023962000-07-11 17:31:38 +1000978 fromlen = sizeof(from);
979 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
980 &fromlen);
981 if (newsock < 0) {
982 if (errno != EINTR && errno != EWOULDBLOCK)
983 error("accept: %.100s", strerror(errno));
984 continue;
985 }
986 if (fcntl(newsock, F_SETFL, 0) < 0) {
987 error("newsock del O_NONBLOCK: %s", strerror(errno));
988 continue;
989 }
Damien Miller942da032000-08-18 13:59:06 +1000990 if (drop_connection(startups) == 1) {
991 debug("drop connection #%d", startups);
Damien Miller37023962000-07-11 17:31:38 +1000992 close(newsock);
993 continue;
994 }
995 if (pipe(startup_p) == -1) {
996 close(newsock);
997 continue;
998 }
999
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];
1005 startups++;
1006 break;
1007 }
Kevin Stevesef4eea92001-02-05 12:42:17 +00001008
Damien Miller5428f641999-11-25 11:54:57 +11001009 /*
Damien Miller37023962000-07-11 17:31:38 +10001010 * Got connection. Fork a child to handle it, unless
1011 * we are in debugging mode.
Damien Miller5428f641999-11-25 11:54:57 +11001012 */
Damien Miller37023962000-07-11 17:31:38 +10001013 if (debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +11001014 /*
Damien Miller37023962000-07-11 17:31:38 +10001015 * In debugging mode. Close the listening
1016 * socket, and start processing the
1017 * connection without forking.
Damien Miller5428f641999-11-25 11:54:57 +11001018 */
Damien Miller37023962000-07-11 17:31:38 +10001019 debug("Server will not fork when running in debugging mode.");
Damien Miller34132e52000-01-14 15:45:46 +11001020 close_listen_socks();
Damien Miller95def091999-11-25 00:26:21 +11001021 sock_in = newsock;
1022 sock_out = newsock;
Damien Miller4d97ba22000-07-11 18:15:50 +10001023 startup_pipe = -1;
Damien Miller182ee6e2000-07-12 09:45:27 +10001024 pid = getpid();
Damien Miller95def091999-11-25 00:26:21 +11001025 break;
Damien Miller37023962000-07-11 17:31:38 +10001026 } else {
1027 /*
1028 * Normal production daemon. Fork, and have
1029 * the child process the connection. The
1030 * parent continues listening.
1031 */
1032 if ((pid = fork()) == 0) {
1033 /*
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
1038 * the connection.
1039 */
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();
1045 sock_in = newsock;
1046 sock_out = newsock;
Kevin Stevesec84dc12000-12-13 17:45:15 +00001047 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller37023962000-07-11 17:31:38 +10001048 break;
1049 }
Damien Miller95def091999-11-25 00:26:21 +11001050 }
Damien Miller37023962000-07-11 17:31:38 +10001051
1052 /* Parent. Stay in the loop. */
1053 if (pid < 0)
1054 error("fork: %.100s", strerror(errno));
1055 else
1056 debug("Forked child %d.", pid);
1057
1058 close(startup_p[1]);
1059
1060 /* Mark that the key has been used (it was "given" to the child). */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001061 if ((options.protocol & SSH_PROTO_1) &&
1062 key_used == 0) {
1063 /* Schedule server key regeneration alarm. */
1064 signal(SIGALRM, key_regeneration_alarm);
1065 alarm(options.key_regeneration_time);
1066 key_used = 1;
1067 }
Damien Miller37023962000-07-11 17:31:38 +10001068
1069 arc4random_stir();
1070
1071 /* Close the new socket (the child is now taking care of it). */
1072 close(newsock);
Damien Miller95def091999-11-25 00:26:21 +11001073 }
Damien Miller34132e52000-01-14 15:45:46 +11001074 /* child process check (or debug mode) */
1075 if (num_listen_socks < 0)
1076 break;
Damien Miller95def091999-11-25 00:26:21 +11001077 }
1078 }
1079
1080 /* This is the child processing a new connection. */
1081
Damien Miller5428f641999-11-25 11:54:57 +11001082 /*
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.
1086 */
Damien Miller95def091999-11-25 00:26:21 +11001087 alarm(0);
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);
Damien Miller4e0f5e12000-08-29 11:05:50 +11001093 signal(SIGINT, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +11001094
Damien Miller5428f641999-11-25 11:54:57 +11001095 /*
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.
1099 */
1100 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
Damien Miller95def091999-11-25 00:26:21 +11001101 linger.l_onoff = 1;
1102 linger.l_linger = 5;
1103 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1104
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001105 /* Set keepalives if requested. */
1106 if (options.keepalives &&
1107 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1108 sizeof(on)) < 0)
1109 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1110
Damien Miller5428f641999-11-25 11:54:57 +11001111 /*
1112 * Register our connection. This turns encryption off because we do
1113 * not have a key.
1114 */
Damien Miller95def091999-11-25 00:26:21 +11001115 packet_set_connection(sock_in, sock_out);
1116
1117 remote_port = get_remote_port();
1118 remote_ip = get_remote_ipaddr();
1119
1120 /* Check whether logins are denied from this host. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001121#ifdef LIBWRAP
Damien Miller34132e52000-01-14 15:45:46 +11001122 /* XXX LIBWRAP noes not know about IPv6 */
Damien Miller95def091999-11-25 00:26:21 +11001123 {
1124 struct request_info req;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001125
Kevin Stevesec84dc12000-12-13 17:45:15 +00001126 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, NULL);
Damien Miller95def091999-11-25 00:26:21 +11001127 fromhost(&req);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001128
Damien Miller95def091999-11-25 00:26:21 +11001129 if (!hosts_access(&req)) {
1130 close(sock_in);
1131 close(sock_out);
1132 refuse(&req);
1133 }
Damien Miller34132e52000-01-14 15:45:46 +11001134/*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
Damien Miller95def091999-11-25 00:26:21 +11001135 }
Damien Miller34132e52000-01-14 15:45:46 +11001136#endif /* LIBWRAP */
Damien Miller95def091999-11-25 00:26:21 +11001137 /* Log the connection. */
1138 verbose("Connection from %.500s port %d", remote_ip, remote_port);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001139
Damien Miller5428f641999-11-25 11:54:57 +11001140 /*
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.
1147 */
Damien Miller95def091999-11-25 00:26:21 +11001148 signal(SIGALRM, grace_alarm_handler);
1149 if (!debug_flag)
1150 alarm(options.login_grace_time);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001151
Damien Millerb38eff82000-04-01 11:09:21 +10001152 sshd_exchange_identification(sock_in, sock_out);
Damien Miller5428f641999-11-25 11:54:57 +11001153 /*
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001154 * Check that the connection comes from a privileged port.
1155 * Rhosts-Authentication only makes sense from priviledged
Damien Miller5428f641999-11-25 11:54:57 +11001156 * 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.
1159 */
Damien Miller95def091999-11-25 00:26:21 +11001160 if (remote_port >= IPPORT_RESERVED ||
1161 remote_port < IPPORT_RESERVED / 2) {
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001162 debug("Rhosts Authentication disabled, "
Damien Miller0bc1bd82000-11-13 22:57:25 +11001163 "originating port not trusted.");
Damien Miller95def091999-11-25 00:26:21 +11001164 options.rhosts_authentication = 0;
Damien Miller95def091999-11-25 00:26:21 +11001165 }
Damien Miller34132e52000-01-14 15:45:46 +11001166#ifdef KRB4
1167 if (!packet_connection_is_ipv4() &&
1168 options.kerberos_authentication) {
1169 debug("Kerberos Authentication disabled, only available for IPv4.");
1170 options.kerberos_authentication = 0;
1171 }
1172#endif /* KRB4 */
Ben Lindstromf79aeff2001-02-10 21:27:11 +00001173#ifdef AFS
1174 /* If machine has AFS, set process authentication group. */
1175 if (k_hasafs()) {
1176 k_setpag();
1177 k_unlog();
1178 }
1179#endif /* AFS */
Damien Miller34132e52000-01-14 15:45:46 +11001180
Damien Miller95def091999-11-25 00:26:21 +11001181 packet_set_nonblocking();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001182
Damien Miller396691a2000-01-20 22:44:08 +11001183 /* perform the key exchange */
Damien Miller396691a2000-01-20 22:44:08 +11001184 /* authenticate user and start session */
Damien Millerefb4afe2000-04-12 18:45:05 +10001185 if (compat20) {
1186 do_ssh2_kex();
1187 do_authentication2();
1188 } else {
1189 do_ssh1_kex();
1190 do_authentication();
1191 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001192
1193#ifdef KRB4
Damien Miller95def091999-11-25 00:26:21 +11001194 /* Cleanup user's ticket cache file. */
1195 if (options.kerberos_ticket_cleanup)
1196 (void) dest_tkt();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001197#endif /* KRB4 */
1198
Damien Miller95def091999-11-25 00:26:21 +11001199 /* The connection has been terminated. */
1200 verbose("Closing connection to %.100s", remote_ip);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001201
Damien Millerbeb4ba51999-12-28 15:09:35 +11001202#ifdef USE_PAM
Damien Millere72b7af1999-12-30 15:08:44 +11001203 finish_pam();
Damien Millerbeb4ba51999-12-28 15:09:35 +11001204#endif /* USE_PAM */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001205
Damien Miller95def091999-11-25 00:26:21 +11001206 packet_close();
1207 exit(0);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001208}
1209
Damien Miller95def091999-11-25 00:26:21 +11001210/*
Damien Miller396691a2000-01-20 22:44:08 +11001211 * SSH1 key exchange
Damien Miller95def091999-11-25 00:26:21 +11001212 */
Damien Miller2ccf6611999-11-15 15:25:10 +11001213void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001214do_ssh1_kex(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001215{
Damien Miller95def091999-11-25 00:26:21 +11001216 int i, len;
Damien Miller396691a2000-01-20 22:44:08 +11001217 int plen, slen;
Damien Miller7650bc62001-01-30 09:27:26 +11001218 int rsafail = 0;
Damien Miller95def091999-11-25 00:26:21 +11001219 BIGNUM *session_key_int;
Ben Lindstrom46c16222000-12-22 01:43:59 +00001220 u_char session_key[SSH_SESSION_KEY_LENGTH];
1221 u_char cookie[8];
1222 u_int cipher_type, auth_mask, protocol_flags;
Damien Miller95def091999-11-25 00:26:21 +11001223 u_int32_t rand = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001224
Damien Miller5428f641999-11-25 11:54:57 +11001225 /*
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.
1233 */
Damien Miller95def091999-11-25 00:26:21 +11001234 for (i = 0; i < 8; i++) {
1235 if (i % 4 == 0)
1236 rand = arc4random();
Damien Miller396691a2000-01-20 22:44:08 +11001237 cookie[i] = rand & 0xff;
Damien Miller95def091999-11-25 00:26:21 +11001238 rand >>= 8;
1239 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001240
Damien Miller5428f641999-11-25 11:54:57 +11001241 /*
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
1244 * spoofing.
1245 */
Damien Miller95def091999-11-25 00:26:21 +11001246 packet_start(SSH_SMSG_PUBLIC_KEY);
1247 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001248 packet_put_char(cookie[i]);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001249
Damien Miller95def091999-11-25 00:26:21 +11001250 /* Store our public server RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001251 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);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001254
Damien Miller95def091999-11-25 00:26:21 +11001255 /* Store our public host RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001256 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);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001259
Damien Miller95def091999-11-25 00:26:21 +11001260 /* Put protocol flags. */
1261 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001262
Damien Miller95def091999-11-25 00:26:21 +11001263 /* Declare which ciphers we support. */
Damien Miller874d77b2000-10-14 16:23:11 +11001264 packet_put_int(cipher_mask_ssh1(0));
Damien Miller95def091999-11-25 00:26:21 +11001265
1266 /* Declare supported authentication types. */
1267 auth_mask = 0;
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;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001274#ifdef KRB4
Damien Miller95def091999-11-25 00:26:21 +11001275 if (options.kerberos_authentication)
1276 auth_mask |= 1 << SSH_AUTH_KERBEROS;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001277#endif
1278#ifdef AFS
Damien Miller95def091999-11-25 00:26:21 +11001279 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;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001283#endif
Ben Lindstrom95fb2dd2001-01-23 03:12:10 +00001284 if (options.challenge_reponse_authentication == 1)
Damien Miller95def091999-11-25 00:26:21 +11001285 auth_mask |= 1 << SSH_AUTH_TIS;
Damien Miller95def091999-11-25 00:26:21 +11001286 if (options.password_authentication)
1287 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1288 packet_put_int(auth_mask);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001289
Damien Miller95def091999-11-25 00:26:21 +11001290 /* Send the packet and wait for it to be sent. */
1291 packet_send();
1292 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001293
Damien Miller0bc1bd82000-11-13 22:57:25 +11001294 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));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001297
Damien Miller95def091999-11-25 00:26:21 +11001298 /* Read clients reply (cipher type and session key). */
1299 packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001300
Damien Miller50945fa1999-12-09 10:31:37 +11001301 /* Get cipher type and check whether we accept this. */
Damien Miller95def091999-11-25 00:26:21 +11001302 cipher_type = packet_get_char();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001303
Damien Miller874d77b2000-10-14 16:23:11 +11001304 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
Damien Miller50945fa1999-12-09 10:31:37 +11001305 packet_disconnect("Warning: client selects unsupported cipher.");
1306
Damien Miller95def091999-11-25 00:26:21 +11001307 /* 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++)
Damien Miller396691a2000-01-20 22:44:08 +11001310 if (cookie[i] != packet_get_char())
Damien Miller95def091999-11-25 00:26:21 +11001311 packet_disconnect("IP Spoofing check bytes do not match.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001312
Damien Miller95def091999-11-25 00:26:21 +11001313 debug("Encryption type: %.200s", cipher_name(cipher_type));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001314
Damien Miller95def091999-11-25 00:26:21 +11001315 /* Get the encrypted integer. */
1316 session_key_int = BN_new();
1317 packet_get_bignum(session_key_int, &slen);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001318
Damien Miller95def091999-11-25 00:26:21 +11001319 protocol_flags = packet_get_int();
1320 packet_set_protocol_flags(protocol_flags);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001321
Damien Miller95def091999-11-25 00:26:21 +11001322 packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001323
Damien Miller5428f641999-11-25 11:54:57 +11001324 /*
1325 * Decrypt it using our private server key and private host key (key
1326 * with larger modulus first).
1327 */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001328 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
Damien Miller7650bc62001-01-30 09:27:26 +11001329 /* Server key has bigger modulus. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001330 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);
Damien Miller95def091999-11-25 00:26:21 +11001337 }
Damien Miller7650bc62001-01-30 09:27:26 +11001338 if (rsa_private_decrypt(session_key_int, session_key_int,
1339 sensitive_data.server_key->rsa) <= 0)
1340 rsafail++;
1341 if (rsa_private_decrypt(session_key_int, session_key_int,
1342 sensitive_data.ssh1_host_key->rsa) <= 0)
1343 rsafail++;
Damien Miller95def091999-11-25 00:26:21 +11001344 } else {
1345 /* Host key has bigger modulus (or they are equal). */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001346 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);
Damien Miller95def091999-11-25 00:26:21 +11001353 }
Damien Miller7650bc62001-01-30 09:27:26 +11001354 if (rsa_private_decrypt(session_key_int, session_key_int,
1355 sensitive_data.ssh1_host_key->rsa) < 0)
1356 rsafail++;
1357 if (rsa_private_decrypt(session_key_int, session_key_int,
1358 sensitive_data.server_key->rsa) < 0)
1359 rsafail++;
Damien Miller95def091999-11-25 00:26:21 +11001360 }
Damien Miller5428f641999-11-25 11:54:57 +11001361 /*
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.
1365 */
Damien Miller7650bc62001-01-30 09:27:26 +11001366 if (!rsafail) {
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: "
Ben Lindstrom31ca54a2001-02-09 02:11:24 +00001371 "session_key_int %d > sizeof(session_key) %lu",
1372 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
Damien Miller7650bc62001-01-30 09:27:26 +11001373 rsafail++;
1374 } else {
1375 memset(session_key, 0, sizeof(session_key));
1376 BN_bn2bin(session_key_int,
1377 session_key + sizeof(session_key) - len);
Ben Lindstromeb648a72001-03-05 06:00:29 +00001378
1379 compute_session_id(session_id, cookie,
1380 sensitive_data.ssh1_host_key->rsa->n,
1381 sensitive_data.server_key->rsa->n);
1382 /*
1383 * Xor the first 16 bytes of the session key with the
1384 * session id.
1385 */
1386 for (i = 0; i < 16; i++)
1387 session_key[i] ^= session_id[i];
Damien Miller7650bc62001-01-30 09:27:26 +11001388 }
1389 }
1390 if (rsafail) {
Ben Lindstromeb648a72001-03-05 06:00:29 +00001391 int bytes = BN_num_bytes(session_key_int);
1392 char *buf = xmalloc(bytes);
1393 MD5_CTX md;
1394
Damien Miller7650bc62001-01-30 09:27:26 +11001395 log("do_connection: generating a fake encryption key");
Ben Lindstromeb648a72001-03-05 06:00:29 +00001396 BN_bn2bin(session_key_int, buf);
1397 MD5_Init(&md);
1398 MD5_Update(&md, buf, bytes);
1399 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1400 MD5_Final(session_key, &md);
1401 MD5_Init(&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);
1407 xfree(buf);
Ben Lindstrom941ac822001-03-05 06:25:23 +00001408 for (i = 0; i < 16; i++)
1409 session_id[i] = session_key[i] ^ session_key[i + 16];
Damien Miller7650bc62001-01-30 09:27:26 +11001410 }
Ben Lindstromeb648a72001-03-05 06:00:29 +00001411 /* Destroy the private and public keys. They will no longer be needed. */
1412 destroy_sensitive_data();
1413
Damien Miller396691a2000-01-20 22:44:08 +11001414 /* Destroy the decrypted integer. It is no longer needed. */
1415 BN_clear_free(session_key_int);
1416
Damien Miller95def091999-11-25 00:26:21 +11001417 /* 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);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001419
Damien Miller95def091999-11-25 00:26:21 +11001420 /* Destroy our copy of the session key. It is no longer needed. */
1421 memset(session_key, 0, sizeof(session_key));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001422
Damien Miller95def091999-11-25 00:26:21 +11001423 debug("Received session key; encryption turned on.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001424
Damien Miller95def091999-11-25 00:26:21 +11001425 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1426 packet_start(SSH_SMSG_SUCCESS);
1427 packet_send();
1428 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001429}
Damien Millerefb4afe2000-04-12 18:45:05 +10001430
1431/*
1432 * SSH2 key exchange: diffie-hellman-group1-sha1
1433 */
1434void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001435do_ssh2_kex(void)
Damien Millerefb4afe2000-04-12 18:45:05 +10001436{
1437 Buffer *server_kexinit;
1438 Buffer *client_kexinit;
Damien Miller874d77b2000-10-14 16:23:11 +11001439 int payload_len;
Damien Millerefb4afe2000-04-12 18:45:05 +10001440 int i;
Damien Millerefb4afe2000-04-12 18:45:05 +10001441 Kex *kex;
Damien Millerefb4afe2000-04-12 18:45:05 +10001442 char *cprop[PROPOSAL_MAX];
Damien Millerefb4afe2000-04-12 18:45:05 +10001443
1444/* KEXINIT */
1445
Damien Miller78928792000-04-12 20:17:38 +10001446 if (options.ciphers != NULL) {
Damien Miller4af51302000-04-16 11:18:38 +10001447 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
Damien Miller78928792000-04-12 20:17:38 +10001448 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1449 }
Ben Lindstrom06b33aa2001-02-15 03:01:59 +00001450 if (options.macs != NULL) {
1451 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1452 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1453 }
Damien Miller0bc1bd82000-11-13 22:57:25 +11001454 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1455
Damien Millerb1715dc2000-05-30 13:44:51 +10001456 server_kexinit = kex_init(myproposal);
Damien Millerefb4afe2000-04-12 18:45:05 +10001457 client_kexinit = xmalloc(sizeof(*client_kexinit));
1458 buffer_init(client_kexinit);
Damien Millerefb4afe2000-04-12 18:45:05 +10001459
Damien Millerb1715dc2000-05-30 13:44:51 +10001460 /* algorithm negotiation */
1461 kex_exchange_kexinit(server_kexinit, client_kexinit, cprop);
1462 kex = kex_choose_conf(cprop, myproposal, 1);
1463 for (i = 0; i < PROPOSAL_MAX; i++)
1464 xfree(cprop[i]);
Damien Millerefb4afe2000-04-12 18:45:05 +10001465
Damien Miller874d77b2000-10-14 16:23:11 +11001466 switch (kex->kex_type) {
1467 case DH_GRP1_SHA1:
1468 ssh_dh1_server(kex, client_kexinit, server_kexinit);
1469 break;
1470 case DH_GEX_SHA1:
1471 ssh_dhgex_server(kex, client_kexinit, server_kexinit);
1472 break;
1473 default:
1474 fatal("Unsupported key exchange %d", kex->kex_type);
1475 }
Damien Millerefb4afe2000-04-12 18:45:05 +10001476
Damien Miller874d77b2000-10-14 16:23:11 +11001477 debug("send SSH2_MSG_NEWKEYS.");
1478 packet_start(SSH2_MSG_NEWKEYS);
1479 packet_send();
1480 packet_write_wait();
1481 debug("done: send SSH2_MSG_NEWKEYS.");
1482
1483 debug("Wait SSH2_MSG_NEWKEYS.");
1484 packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1485 debug("GOT SSH2_MSG_NEWKEYS.");
1486
1487#ifdef DEBUG_KEXDH
1488 /* send 1st encrypted/maced/compressed message */
1489 packet_start(SSH2_MSG_IGNORE);
1490 packet_put_cstring("markus");
1491 packet_send();
1492 packet_write_wait();
1493#endif
1494
1495 debug("done: KEX2.");
1496}
1497
1498/*
1499 * SSH2 key exchange
1500 */
1501
1502/* diffie-hellman-group1-sha1 */
1503
1504void
1505ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1506{
1507#ifdef DEBUG_KEXDH
1508 int i;
1509#endif
1510 int payload_len, dlen;
1511 int slen;
Ben Lindstrom46c16222000-12-22 01:43:59 +00001512 u_char *signature = NULL;
1513 u_char *server_host_key_blob = NULL;
1514 u_int sbloblen;
1515 u_int klen, kout;
1516 u_char *kbuf;
1517 u_char *hash;
Damien Miller874d77b2000-10-14 16:23:11 +11001518 BIGNUM *shared_secret = 0;
1519 DH *dh;
1520 BIGNUM *dh_client_pub = 0;
Damien Miller0bc1bd82000-11-13 22:57:25 +11001521 Key *hostkey;
1522
1523 hostkey = get_hostkey_by_type(kex->hostkey_type);
1524 if (hostkey == NULL)
1525 fatal("Unsupported hostkey type %d", kex->hostkey_type);
Damien Miller874d77b2000-10-14 16:23:11 +11001526
1527/* KEXDH */
Kevin Steves6b875862000-12-15 23:31:01 +00001528 /* generate DH key */
1529 dh = dh_new_group1(); /* XXX depends on 'kex' */
Ben Lindstrom4c4f05e2001-03-06 01:09:20 +00001530 dh_gen_key(dh, kex->we_need * 8);
Kevin Steves6b875862000-12-15 23:31:01 +00001531
Damien Millerefb4afe2000-04-12 18:45:05 +10001532 debug("Wait SSH2_MSG_KEXDH_INIT.");
1533 packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
1534
1535 /* key, cert */
1536 dh_client_pub = BN_new();
1537 if (dh_client_pub == NULL)
1538 fatal("dh_client_pub == NULL");
1539 packet_get_bignum2(dh_client_pub, &dlen);
1540
1541#ifdef DEBUG_KEXDH
1542 fprintf(stderr, "\ndh_client_pub= ");
Damien Miller62cee002000-09-23 17:15:56 +11001543 BN_print_fp(stderr, dh_client_pub);
Damien Millerefb4afe2000-04-12 18:45:05 +10001544 fprintf(stderr, "\n");
1545 debug("bits %d", BN_num_bits(dh_client_pub));
1546#endif
1547
Damien Millerefb4afe2000-04-12 18:45:05 +10001548#ifdef DEBUG_KEXDH
1549 fprintf(stderr, "\np= ");
Damien Miller62cee002000-09-23 17:15:56 +11001550 BN_print_fp(stderr, dh->p);
Damien Millerefb4afe2000-04-12 18:45:05 +10001551 fprintf(stderr, "\ng= ");
Damien Miller62cee002000-09-23 17:15:56 +11001552 bn_print(dh->g);
Damien Millerefb4afe2000-04-12 18:45:05 +10001553 fprintf(stderr, "\npub= ");
Damien Miller62cee002000-09-23 17:15:56 +11001554 BN_print_fp(stderr, dh->pub_key);
Damien Millerefb4afe2000-04-12 18:45:05 +10001555 fprintf(stderr, "\n");
Kevin Stevesef4eea92001-02-05 12:42:17 +00001556 DHparams_print_fp(stderr, dh);
Damien Millerefb4afe2000-04-12 18:45:05 +10001557#endif
Damien Miller78928792000-04-12 20:17:38 +10001558 if (!dh_pub_is_valid(dh, dh_client_pub))
1559 packet_disconnect("bad client public DH value");
Damien Millerefb4afe2000-04-12 18:45:05 +10001560
1561 klen = DH_size(dh);
1562 kbuf = xmalloc(klen);
1563 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1564
1565#ifdef DEBUG_KEXDH
1566 debug("shared secret: len %d/%d", klen, kout);
1567 fprintf(stderr, "shared secret == ");
1568 for (i = 0; i< kout; i++)
1569 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1570 fprintf(stderr, "\n");
1571#endif
1572 shared_secret = BN_new();
1573
1574 BN_bin2bn(kbuf, kout, shared_secret);
1575 memset(kbuf, 0, klen);
1576 xfree(kbuf);
1577
Damien Millereba71ba2000-04-29 23:57:08 +10001578 /* XXX precompute? */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001579 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
Damien Millerefb4afe2000-04-12 18:45:05 +10001580
1581 /* calc H */ /* XXX depends on 'kex' */
1582 hash = kex_hash(
1583 client_version_string,
1584 server_version_string,
1585 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1586 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1587 (char *)server_host_key_blob, sbloblen,
1588 dh_client_pub,
1589 dh->pub_key,
1590 shared_secret
1591 );
1592 buffer_free(client_kexinit);
1593 buffer_free(server_kexinit);
1594 xfree(client_kexinit);
1595 xfree(server_kexinit);
Ben Lindstromb1985f72001-01-23 00:19:15 +00001596 BN_free(dh_client_pub);
Damien Millerefb4afe2000-04-12 18:45:05 +10001597#ifdef DEBUG_KEXDH
Damien Miller4af51302000-04-16 11:18:38 +10001598 fprintf(stderr, "hash == ");
1599 for (i = 0; i< 20; i++)
1600 fprintf(stderr, "%02x", (hash[i])&0xff);
1601 fprintf(stderr, "\n");
Damien Millerefb4afe2000-04-12 18:45:05 +10001602#endif
Damien Millereba71ba2000-04-29 23:57:08 +10001603 /* save session id := H */
1604 /* XXX hashlen depends on KEX */
1605 session_id2_len = 20;
1606 session_id2 = xmalloc(session_id2_len);
1607 memcpy(session_id2, hash, session_id2_len);
1608
Damien Millerefb4afe2000-04-12 18:45:05 +10001609 /* sign H */
Damien Millereba71ba2000-04-29 23:57:08 +10001610 /* XXX hashlen depends on KEX */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001611 key_sign(hostkey, &signature, &slen, hash, 20);
Damien Millereba71ba2000-04-29 23:57:08 +10001612
1613 destroy_sensitive_data();
Damien Millerefb4afe2000-04-12 18:45:05 +10001614
1615 /* send server hostkey, DH pubkey 'f' and singed H */
1616 packet_start(SSH2_MSG_KEXDH_REPLY);
1617 packet_put_string((char *)server_host_key_blob, sbloblen);
Damien Millere247cc42000-05-07 12:03:14 +10001618 packet_put_bignum2(dh->pub_key); /* f */
Damien Millerefb4afe2000-04-12 18:45:05 +10001619 packet_put_string((char *)signature, slen);
1620 packet_send();
Damien Miller8bb73be2000-04-19 16:26:12 +10001621 xfree(signature);
Damien Millereba71ba2000-04-29 23:57:08 +10001622 xfree(server_host_key_blob);
Damien Millerefb4afe2000-04-12 18:45:05 +10001623 packet_write_wait();
1624
1625 kex_derive_keys(kex, hash, shared_secret);
Ben Lindstromb1985f72001-01-23 00:19:15 +00001626 BN_clear_free(shared_secret);
Damien Millerefb4afe2000-04-12 18:45:05 +10001627 packet_set_kex(kex);
1628
1629 /* have keys, free DH */
1630 DH_free(dh);
Damien Miller874d77b2000-10-14 16:23:11 +11001631}
Damien Millerefb4afe2000-04-12 18:45:05 +10001632
Damien Miller874d77b2000-10-14 16:23:11 +11001633/* diffie-hellman-group-exchange-sha1 */
1634
1635void
1636ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1637{
1638#ifdef DEBUG_KEXDH
1639 int i;
1640#endif
1641 int payload_len, dlen;
1642 int slen, nbits;
Ben Lindstrom46c16222000-12-22 01:43:59 +00001643 u_char *signature = NULL;
1644 u_char *server_host_key_blob = NULL;
1645 u_int sbloblen;
1646 u_int klen, kout;
1647 u_char *kbuf;
1648 u_char *hash;
Damien Miller874d77b2000-10-14 16:23:11 +11001649 BIGNUM *shared_secret = 0;
1650 DH *dh;
1651 BIGNUM *dh_client_pub = 0;
Damien Miller0bc1bd82000-11-13 22:57:25 +11001652 Key *hostkey;
1653
1654 hostkey = get_hostkey_by_type(kex->hostkey_type);
1655 if (hostkey == NULL)
1656 fatal("Unsupported hostkey type %d", kex->hostkey_type);
Damien Miller874d77b2000-10-14 16:23:11 +11001657
1658/* KEXDHGEX */
1659 debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST.");
1660 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST);
1661 nbits = packet_get_int();
1662 dh = choose_dh(nbits);
1663
1664 debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP.");
1665 packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
1666 packet_put_bignum2(dh->p);
1667 packet_put_bignum2(dh->g);
Damien Millerefb4afe2000-04-12 18:45:05 +10001668 packet_send();
1669 packet_write_wait();
Damien Millerefb4afe2000-04-12 18:45:05 +10001670
Kevin Steves6b875862000-12-15 23:31:01 +00001671 /* Compute our exchange value in parallel with the client */
1672
Ben Lindstrom4c4f05e2001-03-06 01:09:20 +00001673 dh_gen_key(dh, kex->we_need * 8);
Kevin Steves6b875862000-12-15 23:31:01 +00001674
Damien Miller874d77b2000-10-14 16:23:11 +11001675 debug("Wait SSH2_MSG_KEX_DH_GEX_INIT.");
1676 packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT);
1677
1678 /* key, cert */
1679 dh_client_pub = BN_new();
1680 if (dh_client_pub == NULL)
1681 fatal("dh_client_pub == NULL");
1682 packet_get_bignum2(dh_client_pub, &dlen);
Damien Millerefb4afe2000-04-12 18:45:05 +10001683
Damien Miller78928792000-04-12 20:17:38 +10001684#ifdef DEBUG_KEXDH
Damien Miller874d77b2000-10-14 16:23:11 +11001685 fprintf(stderr, "\ndh_client_pub= ");
1686 BN_print_fp(stderr, dh_client_pub);
1687 fprintf(stderr, "\n");
1688 debug("bits %d", BN_num_bits(dh_client_pub));
Damien Miller78928792000-04-12 20:17:38 +10001689#endif
Damien Miller874d77b2000-10-14 16:23:11 +11001690
1691#ifdef DEBUG_KEXDH
1692 fprintf(stderr, "\np= ");
1693 BN_print_fp(stderr, dh->p);
1694 fprintf(stderr, "\ng= ");
1695 bn_print(dh->g);
1696 fprintf(stderr, "\npub= ");
1697 BN_print_fp(stderr, dh->pub_key);
1698 fprintf(stderr, "\n");
Kevin Stevesef4eea92001-02-05 12:42:17 +00001699 DHparams_print_fp(stderr, dh);
Damien Miller874d77b2000-10-14 16:23:11 +11001700#endif
1701 if (!dh_pub_is_valid(dh, dh_client_pub))
1702 packet_disconnect("bad client public DH value");
1703
1704 klen = DH_size(dh);
1705 kbuf = xmalloc(klen);
1706 kout = DH_compute_key(kbuf, dh_client_pub, dh);
1707
1708#ifdef DEBUG_KEXDH
1709 debug("shared secret: len %d/%d", klen, kout);
1710 fprintf(stderr, "shared secret == ");
1711 for (i = 0; i< kout; i++)
1712 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1713 fprintf(stderr, "\n");
1714#endif
1715 shared_secret = BN_new();
1716
1717 BN_bin2bn(kbuf, kout, shared_secret);
1718 memset(kbuf, 0, klen);
1719 xfree(kbuf);
1720
1721 /* XXX precompute? */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001722 key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
Damien Miller874d77b2000-10-14 16:23:11 +11001723
1724 /* calc H */ /* XXX depends on 'kex' */
1725 hash = kex_hash_gex(
1726 client_version_string,
1727 server_version_string,
1728 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1729 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1730 (char *)server_host_key_blob, sbloblen,
1731 nbits, dh->p, dh->g,
1732 dh_client_pub,
1733 dh->pub_key,
1734 shared_secret
1735 );
1736 buffer_free(client_kexinit);
1737 buffer_free(server_kexinit);
1738 xfree(client_kexinit);
1739 xfree(server_kexinit);
Ben Lindstromb1985f72001-01-23 00:19:15 +00001740 BN_free(dh_client_pub);
Damien Miller874d77b2000-10-14 16:23:11 +11001741#ifdef DEBUG_KEXDH
1742 fprintf(stderr, "hash == ");
1743 for (i = 0; i< 20; i++)
1744 fprintf(stderr, "%02x", (hash[i])&0xff);
1745 fprintf(stderr, "\n");
1746#endif
1747 /* save session id := H */
1748 /* XXX hashlen depends on KEX */
1749 session_id2_len = 20;
1750 session_id2 = xmalloc(session_id2_len);
1751 memcpy(session_id2, hash, session_id2_len);
1752
1753 /* sign H */
1754 /* XXX hashlen depends on KEX */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001755 key_sign(hostkey, &signature, &slen, hash, 20);
Damien Miller874d77b2000-10-14 16:23:11 +11001756
1757 destroy_sensitive_data();
1758
1759 /* send server hostkey, DH pubkey 'f' and singed H */
1760 packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
1761 packet_put_string((char *)server_host_key_blob, sbloblen);
1762 packet_put_bignum2(dh->pub_key); /* f */
1763 packet_put_string((char *)signature, slen);
1764 packet_send();
1765 xfree(signature);
1766 xfree(server_host_key_blob);
1767 packet_write_wait();
1768
1769 kex_derive_keys(kex, hash, shared_secret);
Ben Lindstromb1985f72001-01-23 00:19:15 +00001770 BN_clear_free(shared_secret);
Damien Miller874d77b2000-10-14 16:23:11 +11001771 packet_set_kex(kex);
1772
1773 /* have keys, free DH */
1774 DH_free(dh);
Damien Millerefb4afe2000-04-12 18:45:05 +10001775}