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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"
Ben Lindstromce89dac2001-09-12 16:58:04 +000043RCSID("$OpenBSD: sshd.c,v 1.204 2001/08/23 17:59:31 camield 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"
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +000073#include "dispatch.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100074
75#ifdef LIBWRAP
76#include <tcpd.h>
77#include <syslog.h>
78int allow_severity = LOG_INFO;
79int deny_severity = LOG_WARNING;
80#endif /* LIBWRAP */
81
82#ifndef O_NOCTTY
83#define O_NOCTTY 0
84#endif
85
Ben Lindstrom49a79c02000-11-17 03:47:20 +000086#ifdef HAVE___PROGNAME
87extern char *__progname;
88#else
89char *__progname;
90#endif
91
Damien Millerd4a8b7e1999-10-27 13:42:43 +100092/* Server configuration options. */
93ServerOptions options;
94
95/* Name of the server configuration file. */
Ben Lindstrom226cfa02001-01-22 05:34:40 +000096char *config_file_name = _PATH_SERVER_CONFIG_FILE;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100097
Damien Miller4af51302000-04-16 11:18:38 +100098/*
Damien Miller34132e52000-01-14 15:45:46 +110099 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
100 * Default value is AF_UNSPEC means both IPv4 and IPv6.
101 */
Damien Miller7d80e342000-01-19 14:36:49 +1100102#ifdef IPV4_DEFAULT
103int IPv4or6 = AF_INET;
104#else
Damien Miller34132e52000-01-14 15:45:46 +1100105int IPv4or6 = AF_UNSPEC;
Damien Miller7d80e342000-01-19 14:36:49 +1100106#endif
Damien Miller34132e52000-01-14 15:45:46 +1100107
Damien Miller95def091999-11-25 00:26:21 +1100108/*
109 * Debug mode flag. This can be set on the command line. If debug
110 * mode is enabled, extra debugging output will be sent to the system
111 * log, the daemon will not go to background, and will exit after processing
112 * the first connection.
113 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000114int debug_flag = 0;
115
Ben Lindstrom794325a2001-08-06 21:09:07 +0000116/* Flag indicating that the daemon should only test the configuration and keys. */
117int test_flag = 0;
118
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000119/* Flag indicating that the daemon is being started from inetd. */
120int inetd_flag = 0;
121
Ben Lindstromc72745a2000-12-02 19:03:54 +0000122/* Flag indicating that sshd should not detach and become a daemon. */
123int no_daemon_flag = 0;
124
Damien Miller5ce662a1999-11-11 17:57:39 +1100125/* debug goes to stderr unless inetd_flag is set */
126int log_stderr = 0;
127
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000128/* Saved arguments to main(). */
129char **saved_argv;
Damien Millerb8c656e2000-06-28 15:22:41 +1000130int saved_argc;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000131
Damien Miller5428f641999-11-25 11:54:57 +1100132/*
Damien Miller34132e52000-01-14 15:45:46 +1100133 * The sockets that the server is listening; this is used in the SIGHUP
134 * signal handler.
Damien Miller5428f641999-11-25 11:54:57 +1100135 */
Damien Miller34132e52000-01-14 15:45:46 +1100136#define MAX_LISTEN_SOCKS 16
137int listen_socks[MAX_LISTEN_SOCKS];
138int num_listen_socks = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000139
Damien Miller5428f641999-11-25 11:54:57 +1100140/*
141 * the client's version string, passed by sshd2 in compat mode. if != NULL,
142 * sshd will skip the version-number exchange
143 */
Damien Miller95def091999-11-25 00:26:21 +1100144char *client_version_string = NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000145char *server_version_string = NULL;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000146
Ben Lindstrom8ac91062001-04-04 17:57:54 +0000147/* for rekeying XXX fixme */
148Kex *xxx_kex;
149
Damien Miller5428f641999-11-25 11:54:57 +1100150/*
151 * Any really sensitive data in the application is contained in this
152 * structure. The idea is that this structure could be locked into memory so
153 * that the pages do not get written into swap. However, there are some
154 * problems. The private key contains BIGNUMs, and we do not (in principle)
155 * have access to the internals of them, and locking just the structure is
156 * not very useful. Currently, memory locking is not implemented.
157 */
Damien Miller95def091999-11-25 00:26:21 +1100158struct {
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000159 Key *server_key; /* ephemeral server key */
Damien Miller0bc1bd82000-11-13 22:57:25 +1100160 Key *ssh1_host_key; /* ssh1 host key */
161 Key **host_keys; /* all private host keys */
162 int have_ssh1_key;
163 int have_ssh2_key;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000164 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000165} sensitive_data;
166
Damien Miller5428f641999-11-25 11:54:57 +1100167/*
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000168 * Flag indicating whether the RSA server key needs to be regenerated.
169 * Is set in the SIGALRM handler and cleared when the key is regenerated.
Damien Miller5428f641999-11-25 11:54:57 +1100170 */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000171int key_do_regen = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000172
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000173/* This is set to true when a signal is received. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000174int received_sighup = 0;
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000175int received_sigterm = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000176
Damien Millerb38eff82000-04-01 11:09:21 +1000177/* session identifier, used by RSA-auth */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000178u_char session_id[16];
Damien Millerb38eff82000-04-01 11:09:21 +1000179
Damien Millereba71ba2000-04-29 23:57:08 +1000180/* same for ssh2 */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000181u_char *session_id2 = NULL;
Damien Millereba71ba2000-04-29 23:57:08 +1000182int session_id2_len = 0;
183
Damien Miller942da032000-08-18 13:59:06 +1000184/* record remote hostname or ip */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000185u_int utmp_len = MAXHOSTNAMELEN;
Damien Miller942da032000-08-18 13:59:06 +1000186
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000187/* Prototypes for various functions defined later in this file. */
Ben Lindstrombba81212001-06-25 05:01:22 +0000188void destroy_sensitive_data(void);
Damien Miller98c7ad62000-03-09 21:27:49 +1100189
Ben Lindstrombba81212001-06-25 05:01:22 +0000190static void do_ssh1_kex(void);
191static void do_ssh2_kex(void);
Damien Miller874d77b2000-10-14 16:23:11 +1100192
Damien Miller98c7ad62000-03-09 21:27:49 +1100193/*
Damien Miller34132e52000-01-14 15:45:46 +1100194 * Close all listening sockets
195 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000196static void
Damien Miller34132e52000-01-14 15:45:46 +1100197close_listen_socks(void)
198{
199 int i;
200 for (i = 0; i < num_listen_socks; i++)
201 close(listen_socks[i]);
202 num_listen_socks = -1;
203}
204
205/*
Damien Miller95def091999-11-25 00:26:21 +1100206 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
207 * the effect is to reread the configuration file (and to regenerate
208 * the server key).
209 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000210static void
Damien Miller95def091999-11-25 00:26:21 +1100211sighup_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000212{
Damien Miller95def091999-11-25 00:26:21 +1100213 received_sighup = 1;
214 signal(SIGHUP, sighup_handler);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000215}
216
Damien Miller95def091999-11-25 00:26:21 +1100217/*
218 * Called from the main program after receiving SIGHUP.
219 * Restarts the server.
220 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000221static void
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000222sighup_restart(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000223{
Damien Miller95def091999-11-25 00:26:21 +1100224 log("Received SIGHUP; restarting.");
Damien Miller34132e52000-01-14 15:45:46 +1100225 close_listen_socks();
Damien Miller95def091999-11-25 00:26:21 +1100226 execv(saved_argv[0], saved_argv);
Kevin Stevesec84dc12000-12-13 17:45:15 +0000227 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100228 exit(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000229}
230
Damien Miller95def091999-11-25 00:26:21 +1100231/*
232 * Generic signal handler for terminating signals in the master daemon.
Damien Miller95def091999-11-25 00:26:21 +1100233 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000234static void
Damien Miller95def091999-11-25 00:26:21 +1100235sigterm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000236{
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000237 received_sigterm = sig;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000238}
239
Damien Miller95def091999-11-25 00:26:21 +1100240/*
241 * SIGCHLD handler. This is called whenever a child dies. This will then
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000242 * reap any zombies left by exited children.
Damien Miller95def091999-11-25 00:26:21 +1100243 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000244static void
Damien Miller95def091999-11-25 00:26:21 +1100245main_sigchld_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000246{
Damien Miller95def091999-11-25 00:26:21 +1100247 int save_errno = errno;
248 int status;
Damien Miller431f66b1999-11-21 18:31:57 +1100249
Damien Miller95def091999-11-25 00:26:21 +1100250 while (waitpid(-1, &status, WNOHANG) > 0)
251 ;
Damien Miller431f66b1999-11-21 18:31:57 +1100252
Damien Miller95def091999-11-25 00:26:21 +1100253 signal(SIGCHLD, main_sigchld_handler);
254 errno = save_errno;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000255}
256
Damien Miller95def091999-11-25 00:26:21 +1100257/*
258 * Signal handler for the alarm after the login grace period has expired.
259 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000260static void
Damien Miller95def091999-11-25 00:26:21 +1100261grace_alarm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000262{
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000263 /* XXX no idea how fix this signal handler */
264
Damien Miller95def091999-11-25 00:26:21 +1100265 /* Close the connection. */
266 packet_close();
267
268 /* Log error and exit. */
269 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000270}
271
Damien Miller95def091999-11-25 00:26:21 +1100272/*
Damien Miller95def091999-11-25 00:26:21 +1100273 * Signal handler for the key regeneration alarm. Note that this
274 * alarm only occurs in the daemon waiting for connections, and it does not
275 * do anything with the private key or random state before forking.
276 * Thus there should be no concurrency control/asynchronous execution
277 * problems.
278 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000279static void
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000280generate_ephemeral_server_key(void)
Damien Miller0bc1bd82000-11-13 22:57:25 +1100281{
Ben Lindstromeb648a72001-03-05 06:00:29 +0000282 u_int32_t rand = 0;
283 int i;
284
Ben Lindstroma3700052001-04-05 23:26:32 +0000285 verbose("Generating %s%d bit RSA key.",
Damien Millerff75ac42001-03-30 10:50:32 +1000286 sensitive_data.server_key ? "new " : "", options.server_key_bits);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100287 if (sensitive_data.server_key != NULL)
288 key_free(sensitive_data.server_key);
Ben Lindstroma3700052001-04-05 23:26:32 +0000289 sensitive_data.server_key = key_generate(KEY_RSA1,
Damien Millerff75ac42001-03-30 10:50:32 +1000290 options.server_key_bits);
291 verbose("RSA key generation complete.");
Ben Lindstromeb648a72001-03-05 06:00:29 +0000292
293 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
294 if (i % 4 == 0)
295 rand = arc4random();
296 sensitive_data.ssh1_cookie[i] = rand & 0xff;
297 rand >>= 8;
298 }
299 arc4random_stir();
Damien Miller0bc1bd82000-11-13 22:57:25 +1100300}
Ben Lindstrom2f959b42001-01-11 06:20:23 +0000301
Ben Lindstrombba81212001-06-25 05:01:22 +0000302static void
Damien Miller95def091999-11-25 00:26:21 +1100303key_regeneration_alarm(int sig)
304{
305 int save_errno = errno;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000306 signal(SIGALRM, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +1100307 errno = save_errno;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000308 key_do_regen = 1;
Damien Miller95def091999-11-25 00:26:21 +1100309}
310
Ben Lindstrombba81212001-06-25 05:01:22 +0000311static void
Damien Millerb38eff82000-04-01 11:09:21 +1000312sshd_exchange_identification(int sock_in, int sock_out)
313{
Damien Miller78928792000-04-12 20:17:38 +1000314 int i, mismatch;
Damien Millerb38eff82000-04-01 11:09:21 +1000315 int remote_major, remote_minor;
Damien Miller78928792000-04-12 20:17:38 +1000316 int major, minor;
Damien Millerb38eff82000-04-01 11:09:21 +1000317 char *s;
318 char buf[256]; /* Must not be larger than remote_version. */
319 char remote_version[256]; /* Must be at least as big as buf. */
320
Damien Miller78928792000-04-12 20:17:38 +1000321 if ((options.protocol & SSH_PROTO_1) &&
322 (options.protocol & SSH_PROTO_2)) {
323 major = PROTOCOL_MAJOR_1;
324 minor = 99;
325 } else if (options.protocol & SSH_PROTO_2) {
326 major = PROTOCOL_MAJOR_2;
327 minor = PROTOCOL_MINOR_2;
328 } else {
329 major = PROTOCOL_MAJOR_1;
330 minor = PROTOCOL_MINOR_1;
331 }
332 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
Damien Millerb38eff82000-04-01 11:09:21 +1000333 server_version_string = xstrdup(buf);
334
335 if (client_version_string == NULL) {
336 /* Send our protocol version identification. */
337 if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
338 != strlen(server_version_string)) {
339 log("Could not write ident string to %s.", get_remote_ipaddr());
340 fatal_cleanup();
341 }
342
Ben Lindstrom5393f932001-02-15 03:17:13 +0000343 /* Read other side's version identification. */
Ben Lindstroma3700052001-04-05 23:26:32 +0000344 memset(buf, 0, sizeof(buf));
Damien Millerb38eff82000-04-01 11:09:21 +1000345 for (i = 0; i < sizeof(buf) - 1; i++) {
Damien Millerbf7f4662000-06-23 10:16:38 +1000346 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
Ben Lindstroma9a29e12001-02-20 01:20:47 +0000347 log("Did not receive identification string from %s.",
348 get_remote_ipaddr());
Damien Millerb38eff82000-04-01 11:09:21 +1000349 fatal_cleanup();
350 }
351 if (buf[i] == '\r') {
Ben Lindstrom69d8c072001-03-22 22:45:33 +0000352 buf[i] = 0;
Damien Miller874d77b2000-10-14 16:23:11 +1100353 /* Kludge for F-Secure Macintosh < 1.0.2 */
354 if (i == 12 &&
355 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
356 break;
Damien Millerb38eff82000-04-01 11:09:21 +1000357 continue;
Damien Millerb38eff82000-04-01 11:09:21 +1000358 }
359 if (buf[i] == '\n') {
Ben Lindstrom69d8c072001-03-22 22:45:33 +0000360 buf[i] = 0;
Damien Millerb38eff82000-04-01 11:09:21 +1000361 break;
362 }
363 }
364 buf[sizeof(buf) - 1] = 0;
365 client_version_string = xstrdup(buf);
366 }
367
368 /*
369 * Check that the versions match. In future this might accept
370 * several versions and set appropriate flags to handle them.
371 */
372 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
373 &remote_major, &remote_minor, remote_version) != 3) {
Damien Miller4af51302000-04-16 11:18:38 +1000374 s = "Protocol mismatch.\n";
Damien Millerb38eff82000-04-01 11:09:21 +1000375 (void) atomicio(write, sock_out, s, strlen(s));
376 close(sock_in);
377 close(sock_out);
378 log("Bad protocol version identification '%.100s' from %s",
379 client_version_string, get_remote_ipaddr());
380 fatal_cleanup();
381 }
382 debug("Client protocol version %d.%d; client software version %.100s",
383 remote_major, remote_minor, remote_version);
384
Damien Millerefb4afe2000-04-12 18:45:05 +1000385 compat_datafellows(remote_version);
386
Damien Miller27dbe6f2001-03-19 22:36:20 +1100387 if (datafellows & SSH_BUG_SCANNER) {
388 log("scanned from %s with %s. Don't panic.",
389 get_remote_ipaddr(), client_version_string);
390 fatal_cleanup();
391 }
392
Damien Miller78928792000-04-12 20:17:38 +1000393 mismatch = 0;
Damien Millerb38eff82000-04-01 11:09:21 +1000394 switch(remote_major) {
395 case 1:
Damien Millereba71ba2000-04-29 23:57:08 +1000396 if (remote_minor == 99) {
397 if (options.protocol & SSH_PROTO_2)
398 enable_compat20();
399 else
400 mismatch = 1;
401 break;
402 }
Damien Miller78928792000-04-12 20:17:38 +1000403 if (!(options.protocol & SSH_PROTO_1)) {
404 mismatch = 1;
405 break;
406 }
Damien Millerb38eff82000-04-01 11:09:21 +1000407 if (remote_minor < 3) {
Damien Miller37023962000-07-11 17:31:38 +1000408 packet_disconnect("Your ssh version is too old and "
Damien Millerb38eff82000-04-01 11:09:21 +1000409 "is no longer supported. Please install a newer version.");
410 } else if (remote_minor == 3) {
411 /* note that this disables agent-forwarding */
412 enable_compat13();
413 }
Damien Miller78928792000-04-12 20:17:38 +1000414 break;
Damien Millerefb4afe2000-04-12 18:45:05 +1000415 case 2:
Damien Miller78928792000-04-12 20:17:38 +1000416 if (options.protocol & SSH_PROTO_2) {
Damien Millerefb4afe2000-04-12 18:45:05 +1000417 enable_compat20();
418 break;
419 }
420 /* FALLTHROUGH */
Damien Miller4af51302000-04-16 11:18:38 +1000421 default:
Damien Miller78928792000-04-12 20:17:38 +1000422 mismatch = 1;
Damien Millerb38eff82000-04-01 11:09:21 +1000423 break;
424 }
Damien Millerefb4afe2000-04-12 18:45:05 +1000425 chop(server_version_string);
Damien Miller78928792000-04-12 20:17:38 +1000426 debug("Local version string %.200s", server_version_string);
427
428 if (mismatch) {
429 s = "Protocol major versions differ.\n";
430 (void) atomicio(write, sock_out, s, strlen(s));
431 close(sock_in);
432 close(sock_out);
433 log("Protocol major versions differ for %s: %.200s vs. %.200s",
434 get_remote_ipaddr(),
435 server_version_string, client_version_string);
436 fatal_cleanup();
437 }
Damien Millereba71ba2000-04-29 23:57:08 +1000438}
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}
Damien Miller0bc1bd82000-11-13 22:57:25 +1100460
Ben Lindstrombba81212001-06-25 05:01:22 +0000461static char *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100462list_hostkey_types(void)
463{
464 static char buf[1024];
465 int i;
466 buf[0] = '\0';
467 for(i = 0; i < options.num_host_key_files; i++) {
468 Key *key = sensitive_data.host_keys[i];
469 if (key == NULL)
470 continue;
471 switch(key->type) {
472 case KEY_RSA:
473 case KEY_DSA:
474 strlcat(buf, key_ssh_name(key), sizeof buf);
475 strlcat(buf, ",", sizeof buf);
476 break;
477 }
478 }
479 i = strlen(buf);
480 if (i > 0 && buf[i-1] == ',')
481 buf[i-1] = '\0';
482 debug("list_hostkey_types: %s", buf);
483 return buf;
484}
485
Ben Lindstrombba81212001-06-25 05:01:22 +0000486static Key *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100487get_hostkey_by_type(int type)
488{
489 int i;
490 for(i = 0; i < options.num_host_key_files; i++) {
491 Key *key = sensitive_data.host_keys[i];
492 if (key != NULL && key->type == type)
493 return key;
494 }
495 return NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000496}
497
Damien Miller942da032000-08-18 13:59:06 +1000498/*
499 * returns 1 if connection should be dropped, 0 otherwise.
500 * dropping starts at connection #max_startups_begin with a probability
501 * of (max_startups_rate/100). the probability increases linearly until
502 * all connections are dropped for startups > max_startups
503 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000504static int
Damien Miller942da032000-08-18 13:59:06 +1000505drop_connection(int startups)
506{
507 double p, r;
508
509 if (startups < options.max_startups_begin)
510 return 0;
511 if (startups >= options.max_startups)
512 return 1;
513 if (options.max_startups_rate == 100)
514 return 1;
515
516 p = 100 - options.max_startups_rate;
517 p *= startups - options.max_startups_begin;
518 p /= (double) (options.max_startups - options.max_startups_begin);
519 p += options.max_startups_rate;
520 p /= 100.0;
521 r = arc4random() / (double) UINT_MAX;
522
523 debug("drop_connection: p %g, r %g", p, r);
524 return (r < p) ? 1 : 0;
525}
526
Damien Miller37023962000-07-11 17:31:38 +1000527int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
528int startup_pipe; /* in child */
529
Damien Miller95def091999-11-25 00:26:21 +1100530/*
531 * Main program for the daemon.
532 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000533int
534main(int ac, char **av)
535{
Damien Miller95def091999-11-25 00:26:21 +1100536 extern char *optarg;
537 extern int optind;
Damien Miller37023962000-07-11 17:31:38 +1000538 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
Damien Miller166fca82000-04-20 07:42:21 +1000539 pid_t pid;
Damien Miller34132e52000-01-14 15:45:46 +1100540 socklen_t fromlen;
Damien Miller34132e52000-01-14 15:45:46 +1100541 fd_set *fdset;
542 struct sockaddr_storage from;
Damien Miller95def091999-11-25 00:26:21 +1100543 const char *remote_ip;
544 int remote_port;
Damien Miller95def091999-11-25 00:26:21 +1100545 FILE *f;
546 struct linger linger;
Damien Miller34132e52000-01-14 15:45:46 +1100547 struct addrinfo *ai;
548 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
549 int listen_sock, maxfd;
Damien Miller37023962000-07-11 17:31:38 +1000550 int startup_p[2];
551 int startups = 0;
Ben Lindstromd0fca422001-03-26 13:44:06 +0000552 Key *key;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000553 int ret, key_used = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000554
Ben Lindstrom49a79c02000-11-17 03:47:20 +0000555 __progname = get_progname(av[0]);
Damien Millerf9b625c2000-07-09 22:42:32 +1000556 init_rng();
557
Kevin Stevesec84dc12000-12-13 17:45:15 +0000558 /* Save argv. */
Damien Millerb8c656e2000-06-28 15:22:41 +1000559 saved_argc = ac;
Damien Miller95def091999-11-25 00:26:21 +1100560 saved_argv = av;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000561
Damien Miller95def091999-11-25 00:26:21 +1100562 /* Initialize configuration options to their default values. */
563 initialize_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000564
Damien Miller95def091999-11-25 00:26:21 +1100565 /* Parse command-line arguments. */
Ben Lindstrom794325a2001-08-06 21:09:07 +0000566 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDeiqtQ46")) != -1) {
Damien Miller95def091999-11-25 00:26:21 +1100567 switch (opt) {
Damien Miller34132e52000-01-14 15:45:46 +1100568 case '4':
569 IPv4or6 = AF_INET;
570 break;
571 case '6':
572 IPv4or6 = AF_INET6;
573 break;
Damien Miller95def091999-11-25 00:26:21 +1100574 case 'f':
575 config_file_name = optarg;
576 break;
577 case 'd':
Damien Millere4340be2000-09-16 13:29:08 +1100578 if (0 == debug_flag) {
579 debug_flag = 1;
580 options.log_level = SYSLOG_LEVEL_DEBUG1;
581 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
582 options.log_level++;
583 } else {
584 fprintf(stderr, "Too high debugging level.\n");
585 exit(1);
586 }
Damien Miller95def091999-11-25 00:26:21 +1100587 break;
Ben Lindstromc72745a2000-12-02 19:03:54 +0000588 case 'D':
589 no_daemon_flag = 1;
590 break;
Ben Lindstrom9fce9f02001-04-11 23:10:09 +0000591 case 'e':
592 log_stderr = 1;
593 break;
Damien Miller95def091999-11-25 00:26:21 +1100594 case 'i':
595 inetd_flag = 1;
596 break;
597 case 'Q':
Ben Lindstromd5390202001-01-29 08:07:43 +0000598 /* ignored */
Damien Miller95def091999-11-25 00:26:21 +1100599 break;
600 case 'q':
601 options.log_level = SYSLOG_LEVEL_QUIET;
602 break;
603 case 'b':
604 options.server_key_bits = atoi(optarg);
605 break;
606 case 'p':
Damien Miller34132e52000-01-14 15:45:46 +1100607 options.ports_from_cmdline = 1;
Damien Millere4340be2000-09-16 13:29:08 +1100608 if (options.num_ports >= MAX_PORTS) {
609 fprintf(stderr, "too many ports.\n");
610 exit(1);
611 }
Ben Lindstrom19066a12001-04-12 23:39:26 +0000612 options.ports[options.num_ports++] = a2port(optarg);
613 if (options.ports[options.num_ports-1] == 0) {
614 fprintf(stderr, "Bad port number.\n");
615 exit(1);
616 }
Damien Miller95def091999-11-25 00:26:21 +1100617 break;
618 case 'g':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000619 if ((options.login_grace_time = convtime(optarg)) == -1) {
620 fprintf(stderr, "Invalid login grace time.\n");
621 exit(1);
622 }
Damien Miller95def091999-11-25 00:26:21 +1100623 break;
624 case 'k':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000625 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
626 fprintf(stderr, "Invalid key regeneration interval.\n");
627 exit(1);
628 }
Damien Miller95def091999-11-25 00:26:21 +1100629 break;
630 case 'h':
Damien Miller0bc1bd82000-11-13 22:57:25 +1100631 if (options.num_host_key_files >= MAX_HOSTKEYS) {
632 fprintf(stderr, "too many host keys.\n");
633 exit(1);
634 }
635 options.host_key_files[options.num_host_key_files++] = optarg;
Damien Miller95def091999-11-25 00:26:21 +1100636 break;
637 case 'V':
638 client_version_string = optarg;
639 /* only makes sense with inetd_flag, i.e. no listen() */
640 inetd_flag = 1;
641 break;
Ben Lindstrom794325a2001-08-06 21:09:07 +0000642 case 't':
643 test_flag = 1;
644 break;
Damien Miller942da032000-08-18 13:59:06 +1000645 case 'u':
646 utmp_len = atoi(optarg);
647 break;
Damien Miller95def091999-11-25 00:26:21 +1100648 case '?':
649 default:
650 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
Kevin Stevesec84dc12000-12-13 17:45:15 +0000651 fprintf(stderr, "Usage: %s [options]\n", __progname);
Damien Miller95def091999-11-25 00:26:21 +1100652 fprintf(stderr, "Options:\n");
Ben Lindstrom226cfa02001-01-22 05:34:40 +0000653 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
Damien Millere4340be2000-09-16 13:29:08 +1100654 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
Damien Miller95def091999-11-25 00:26:21 +1100655 fprintf(stderr, " -i Started from inetd\n");
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000656 fprintf(stderr, " -D Do not fork into daemon mode\n");
Ben Lindstrom794325a2001-08-06 21:09:07 +0000657 fprintf(stderr, " -t Only test configuration file and keys\n");
Damien Miller95def091999-11-25 00:26:21 +1100658 fprintf(stderr, " -q Quiet (no logging)\n");
659 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
660 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
Ben Lindstromd26dcf32001-01-06 15:18:16 +0000661 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
Damien Miller95def091999-11-25 00:26:21 +1100662 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
663 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
Ben Lindstrom226cfa02001-01-22 05:34:40 +0000664 _PATH_HOST_KEY_FILE);
Damien Miller942da032000-08-18 13:59:06 +1000665 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
Damien Miller34132e52000-01-14 15:45:46 +1100666 fprintf(stderr, " -4 Use IPv4 only\n");
667 fprintf(stderr, " -6 Use IPv6 only\n");
Damien Miller95def091999-11-25 00:26:21 +1100668 exit(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000669 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000670 }
Ben Lindstrom425fb022001-03-29 00:31:20 +0000671 SSLeay_add_all_algorithms();
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000672
Damien Miller34132e52000-01-14 15:45:46 +1100673 /*
674 * Force logging to stderr until we have loaded the private host
675 * key (unless started from inetd)
676 */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000677 log_init(__progname,
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000678 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
Damien Miller34132e52000-01-14 15:45:46 +1100679 options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
Ben Lindstromd5390202001-01-29 08:07:43 +0000680 !inetd_flag);
Damien Miller34132e52000-01-14 15:45:46 +1100681
Ben Lindstrom6db66ff2001-08-06 23:29:16 +0000682#ifdef _CRAY
683 /* Cray can define user privs drop all prives now!
684 * Not needed on PRIV_SU systems!
685 */
686 drop_cray_privs();
687#endif
688
Damien Miller60bc5172001-03-19 09:38:15 +1100689 seed_rng();
690
Damien Miller95def091999-11-25 00:26:21 +1100691 /* Read server configuration options from the configuration file. */
692 read_server_config(&options, config_file_name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000693
Damien Miller95def091999-11-25 00:26:21 +1100694 /* Fill in default values for those options not explicitly set. */
695 fill_default_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000696
Damien Miller95def091999-11-25 00:26:21 +1100697 /* Check that there are no remaining arguments. */
698 if (optind < ac) {
699 fprintf(stderr, "Extra argument %s.\n", av[optind]);
700 exit(1);
701 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000702
Damien Miller95def091999-11-25 00:26:21 +1100703 debug("sshd version %.100s", SSH_VERSION);
Damien Miller2ccf6611999-11-15 15:25:10 +1100704
Damien Miller0bc1bd82000-11-13 22:57:25 +1100705 /* load private host keys */
706 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
Ben Lindstrom46c16222000-12-22 01:43:59 +0000707 for(i = 0; i < options.num_host_key_files; i++)
708 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100709 sensitive_data.server_key = NULL;
710 sensitive_data.ssh1_host_key = NULL;
711 sensitive_data.have_ssh1_key = 0;
712 sensitive_data.have_ssh2_key = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000713
Damien Miller0bc1bd82000-11-13 22:57:25 +1100714 for(i = 0; i < options.num_host_key_files; i++) {
Ben Lindstromd0fca422001-03-26 13:44:06 +0000715 key = key_load_private(options.host_key_files[i], "", NULL);
716 sensitive_data.host_keys[i] = key;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100717 if (key == NULL) {
Ben Lindstrom15f33862001-04-16 02:00:02 +0000718 error("Could not load host key: %s",
719 options.host_key_files[i]);
Ben Lindstromd0fca422001-03-26 13:44:06 +0000720 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100721 continue;
722 }
723 switch(key->type){
724 case KEY_RSA1:
725 sensitive_data.ssh1_host_key = key;
726 sensitive_data.have_ssh1_key = 1;
727 break;
728 case KEY_RSA:
729 case KEY_DSA:
730 sensitive_data.have_ssh2_key = 1;
731 break;
732 }
Ben Lindstromd0fca422001-03-26 13:44:06 +0000733 debug("private host key: #%d type %d %s", i, key->type,
734 key_type(key));
Damien Miller0bc1bd82000-11-13 22:57:25 +1100735 }
736 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
737 log("Disabling protocol version 1. Could not load host key");
Damien Millereba71ba2000-04-29 23:57:08 +1000738 options.protocol &= ~SSH_PROTO_1;
739 }
Damien Miller0bc1bd82000-11-13 22:57:25 +1100740 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
741 log("Disabling protocol version 2. Could not load host key");
742 options.protocol &= ~SSH_PROTO_2;
Damien Millereba71ba2000-04-29 23:57:08 +1000743 }
Kevin Stevesadf74cd2001-02-05 14:22:50 +0000744 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
Ben Lindstrom6df8ef42001-03-05 07:47:23 +0000745 log("sshd: no hostkeys available -- exiting.");
Damien Miller95def091999-11-25 00:26:21 +1100746 exit(1);
747 }
Damien Miller95def091999-11-25 00:26:21 +1100748
Damien Millereba71ba2000-04-29 23:57:08 +1000749 /* Check certain values for sanity. */
750 if (options.protocol & SSH_PROTO_1) {
751 if (options.server_key_bits < 512 ||
752 options.server_key_bits > 32768) {
753 fprintf(stderr, "Bad server key size.\n");
754 exit(1);
755 }
756 /*
757 * Check that server and host key lengths differ sufficiently. This
758 * is necessary to make double encryption work with rsaref. Oh, I
759 * hate software patents. I dont know if this can go? Niels
760 */
761 if (options.server_key_bits >
Damien Miller0bc1bd82000-11-13 22:57:25 +1100762 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
Damien Millereba71ba2000-04-29 23:57:08 +1000763 options.server_key_bits <
Damien Miller0bc1bd82000-11-13 22:57:25 +1100764 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
Damien Millereba71ba2000-04-29 23:57:08 +1000765 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 debug("Forcing server key to %d bits to make it differ from host key.",
768 options.server_key_bits);
769 }
770 }
771
Ben Lindstrom794325a2001-08-06 21:09:07 +0000772 /* Configuration looks good, so exit if in test mode. */
773 if (test_flag)
774 exit(0);
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("/");
Ben Lindstromde71cda2001-03-24 00:43:26 +0000815
816 /* ignore SIGPIPE */
817 signal(SIGPIPE, SIG_IGN);
Damien Miller95def091999-11-25 00:26:21 +1100818
Damien Miller95def091999-11-25 00:26:21 +1100819 /* Start listening for a socket, unless started from inetd. */
820 if (inetd_flag) {
Ben Lindstrom206941f2001-04-15 14:27:16 +0000821 int s1;
Damien Miller95def091999-11-25 00:26:21 +1100822 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
Ben Lindstrom206941f2001-04-15 14:27:16 +0000823 dup(s1);
Damien Miller95def091999-11-25 00:26:21 +1100824 sock_in = dup(0);
825 sock_out = dup(1);
Damien Miller994cf142000-07-21 10:19:44 +1000826 startup_pipe = -1;
Damien Millereba71ba2000-04-29 23:57:08 +1000827 /*
828 * We intentionally do not close the descriptors 0, 1, and 2
829 * as our code for setting the descriptors won\'t work if
830 * ttyfd happens to be one of those.
831 */
Damien Miller95def091999-11-25 00:26:21 +1100832 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100833 if (options.protocol & SSH_PROTO_1)
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000834 generate_ephemeral_server_key();
Damien Miller95def091999-11-25 00:26:21 +1100835 } else {
Damien Miller34132e52000-01-14 15:45:46 +1100836 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
837 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
838 continue;
839 if (num_listen_socks >= MAX_LISTEN_SOCKS)
840 fatal("Too many listen sockets. "
841 "Enlarge MAX_LISTEN_SOCKS");
842 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
843 ntop, sizeof(ntop), strport, sizeof(strport),
844 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
845 error("getnameinfo failed");
846 continue;
847 }
848 /* Create socket for listening. */
849 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
850 if (listen_sock < 0) {
851 /* kernel may not support ipv6 */
852 verbose("socket: %.100s", strerror(errno));
853 continue;
854 }
855 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
856 error("listen_sock O_NONBLOCK: %s", strerror(errno));
857 close(listen_sock);
858 continue;
859 }
860 /*
861 * Set socket options. We try to make the port
862 * reusable and have it close as fast as possible
863 * without waiting in unnecessary wait states on
864 * close.
865 */
866 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
867 (void *) &on, sizeof(on));
868 linger.l_onoff = 1;
869 linger.l_linger = 5;
870 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
871 (void *) &linger, sizeof(linger));
Damien Miller95def091999-11-25 00:26:21 +1100872
Damien Miller34132e52000-01-14 15:45:46 +1100873 debug("Bind to port %s on %s.", strport, ntop);
Damien Miller95def091999-11-25 00:26:21 +1100874
Damien Miller34132e52000-01-14 15:45:46 +1100875 /* Bind the socket to the desired port. */
Damien Miller0a4e27d2001-02-18 12:36:39 +1100876 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
877 if (!ai->ai_next)
878 error("Bind to port %s on %s failed: %.200s.",
879 strport, ntop, strerror(errno));
Damien Miller34132e52000-01-14 15:45:46 +1100880 close(listen_sock);
881 continue;
882 }
883 listen_socks[num_listen_socks] = listen_sock;
884 num_listen_socks++;
Damien Miller95def091999-11-25 00:26:21 +1100885
Damien Miller34132e52000-01-14 15:45:46 +1100886 /* Start listening on the port. */
887 log("Server listening on %s port %s.", ntop, strport);
888 if (listen(listen_sock, 5) < 0)
889 fatal("listen: %.100s", strerror(errno));
890
Damien Miller95def091999-11-25 00:26:21 +1100891 }
Damien Miller34132e52000-01-14 15:45:46 +1100892 freeaddrinfo(options.listen_addrs);
893
894 if (!num_listen_socks)
895 fatal("Cannot bind any address.");
896
Ben Lindstrom98097862001-06-25 05:10:20 +0000897 if (options.protocol & SSH_PROTO_1)
898 generate_ephemeral_server_key();
899
900 /*
901 * Arrange to restart on SIGHUP. The handler needs
902 * listen_sock.
903 */
904 signal(SIGHUP, sighup_handler);
905
906 signal(SIGTERM, sigterm_handler);
907 signal(SIGQUIT, sigterm_handler);
908
909 /* Arrange SIGCHLD to be caught. */
910 signal(SIGCHLD, main_sigchld_handler);
911
912 /* Write out the pid file after the sigterm handler is setup */
Damien Miller95def091999-11-25 00:26:21 +1100913 if (!debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +1100914 /*
Ben Lindstrom7ad97102000-12-06 01:42:49 +0000915 * Record our pid in /var/run/sshd.pid to make it
916 * easier to kill the correct sshd. We don't want to
917 * do this before the bind above because the bind will
Damien Miller5428f641999-11-25 11:54:57 +1100918 * fail if there already is a daemon, and this will
919 * overwrite any old pid in the file.
920 */
Damien Millerbac2d8a2000-09-05 16:13:06 +1100921 f = fopen(options.pid_file, "wb");
Damien Miller95def091999-11-25 00:26:21 +1100922 if (f) {
Ben Lindstrom46c16222000-12-22 01:43:59 +0000923 fprintf(f, "%u\n", (u_int) getpid());
Damien Miller95def091999-11-25 00:26:21 +1100924 fclose(f);
925 }
926 }
Damien Miller95def091999-11-25 00:26:21 +1100927
Damien Miller34132e52000-01-14 15:45:46 +1100928 /* setup fd set for listen */
Damien Miller37023962000-07-11 17:31:38 +1000929 fdset = NULL;
Damien Miller34132e52000-01-14 15:45:46 +1100930 maxfd = 0;
931 for (i = 0; i < num_listen_socks; i++)
932 if (listen_socks[i] > maxfd)
933 maxfd = listen_socks[i];
Damien Miller37023962000-07-11 17:31:38 +1000934 /* pipes connected to unauthenticated childs */
935 startup_pipes = xmalloc(options.max_startups * sizeof(int));
936 for (i = 0; i < options.max_startups; i++)
937 startup_pipes[i] = -1;
Damien Miller34132e52000-01-14 15:45:46 +1100938
Damien Miller5428f641999-11-25 11:54:57 +1100939 /*
940 * Stay listening for connections until the system crashes or
941 * the daemon is killed with a signal.
942 */
Damien Miller95def091999-11-25 00:26:21 +1100943 for (;;) {
944 if (received_sighup)
945 sighup_restart();
Damien Miller37023962000-07-11 17:31:38 +1000946 if (fdset != NULL)
947 xfree(fdset);
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000948 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
Damien Miller37023962000-07-11 17:31:38 +1000949 fdset = (fd_set *)xmalloc(fdsetsz);
Damien Miller34132e52000-01-14 15:45:46 +1100950 memset(fdset, 0, fdsetsz);
Damien Miller37023962000-07-11 17:31:38 +1000951
Damien Miller34132e52000-01-14 15:45:46 +1100952 for (i = 0; i < num_listen_socks; i++)
953 FD_SET(listen_socks[i], fdset);
Damien Miller37023962000-07-11 17:31:38 +1000954 for (i = 0; i < options.max_startups; i++)
955 if (startup_pipes[i] != -1)
956 FD_SET(startup_pipes[i], fdset);
957
958 /* Wait in select until there is a connection. */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000959 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
960 if (ret < 0 && errno != EINTR)
961 error("select: %.100s", strerror(errno));
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000962 if (received_sigterm) {
963 log("Received signal %d; terminating.",
964 received_sigterm);
965 close_listen_socks();
966 unlink(options.pid_file);
967 exit(255);
968 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000969 if (key_used && key_do_regen) {
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000970 generate_ephemeral_server_key();
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000971 key_used = 0;
972 key_do_regen = 0;
Damien Miller34132e52000-01-14 15:45:46 +1100973 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000974 if (ret < 0)
975 continue;
976
Damien Miller37023962000-07-11 17:31:38 +1000977 for (i = 0; i < options.max_startups; i++)
978 if (startup_pipes[i] != -1 &&
979 FD_ISSET(startup_pipes[i], fdset)) {
980 /*
981 * the read end of the pipe is ready
982 * if the child has closed the pipe
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000983 * after successful authentication
Damien Miller37023962000-07-11 17:31:38 +1000984 * or if the child has died
985 */
986 close(startup_pipes[i]);
987 startup_pipes[i] = -1;
988 startups--;
989 }
Damien Miller34132e52000-01-14 15:45:46 +1100990 for (i = 0; i < num_listen_socks; i++) {
991 if (!FD_ISSET(listen_socks[i], fdset))
Damien Miller95def091999-11-25 00:26:21 +1100992 continue;
Damien Miller37023962000-07-11 17:31:38 +1000993 fromlen = sizeof(from);
994 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
995 &fromlen);
996 if (newsock < 0) {
997 if (errno != EINTR && errno != EWOULDBLOCK)
998 error("accept: %.100s", strerror(errno));
999 continue;
1000 }
1001 if (fcntl(newsock, F_SETFL, 0) < 0) {
1002 error("newsock del O_NONBLOCK: %s", strerror(errno));
1003 continue;
1004 }
Damien Miller942da032000-08-18 13:59:06 +10001005 if (drop_connection(startups) == 1) {
1006 debug("drop connection #%d", startups);
Damien Miller37023962000-07-11 17:31:38 +10001007 close(newsock);
1008 continue;
1009 }
1010 if (pipe(startup_p) == -1) {
1011 close(newsock);
1012 continue;
1013 }
1014
1015 for (j = 0; j < options.max_startups; j++)
1016 if (startup_pipes[j] == -1) {
1017 startup_pipes[j] = startup_p[0];
1018 if (maxfd < startup_p[0])
1019 maxfd = startup_p[0];
1020 startups++;
1021 break;
1022 }
Kevin Stevesef4eea92001-02-05 12:42:17 +00001023
Damien Miller5428f641999-11-25 11:54:57 +11001024 /*
Damien Miller37023962000-07-11 17:31:38 +10001025 * Got connection. Fork a child to handle it, unless
1026 * we are in debugging mode.
Damien Miller5428f641999-11-25 11:54:57 +11001027 */
Damien Miller37023962000-07-11 17:31:38 +10001028 if (debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +11001029 /*
Damien Miller37023962000-07-11 17:31:38 +10001030 * In debugging mode. Close the listening
1031 * socket, and start processing the
1032 * connection without forking.
Damien Miller5428f641999-11-25 11:54:57 +11001033 */
Damien Miller37023962000-07-11 17:31:38 +10001034 debug("Server will not fork when running in debugging mode.");
Damien Miller34132e52000-01-14 15:45:46 +11001035 close_listen_socks();
Damien Miller95def091999-11-25 00:26:21 +11001036 sock_in = newsock;
1037 sock_out = newsock;
Damien Miller4d97ba22000-07-11 18:15:50 +10001038 startup_pipe = -1;
Damien Miller182ee6e2000-07-12 09:45:27 +10001039 pid = getpid();
Damien Miller95def091999-11-25 00:26:21 +11001040 break;
Damien Miller37023962000-07-11 17:31:38 +10001041 } else {
1042 /*
1043 * Normal production daemon. Fork, and have
1044 * the child process the connection. The
1045 * parent continues listening.
1046 */
1047 if ((pid = fork()) == 0) {
1048 /*
1049 * Child. Close the listening and max_startup
1050 * sockets. Start using the accepted socket.
1051 * Reinitialize logging (since our pid has
1052 * changed). We break out of the loop to handle
1053 * the connection.
1054 */
1055 startup_pipe = startup_p[1];
1056 for (j = 0; j < options.max_startups; j++)
1057 if (startup_pipes[j] != -1)
1058 close(startup_pipes[j]);
1059 close_listen_socks();
1060 sock_in = newsock;
1061 sock_out = newsock;
Kevin Stevesec84dc12000-12-13 17:45:15 +00001062 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller37023962000-07-11 17:31:38 +10001063 break;
1064 }
Damien Miller95def091999-11-25 00:26:21 +11001065 }
Damien Miller37023962000-07-11 17:31:38 +10001066
1067 /* Parent. Stay in the loop. */
1068 if (pid < 0)
1069 error("fork: %.100s", strerror(errno));
1070 else
1071 debug("Forked child %d.", pid);
1072
1073 close(startup_p[1]);
1074
1075 /* Mark that the key has been used (it was "given" to the child). */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001076 if ((options.protocol & SSH_PROTO_1) &&
1077 key_used == 0) {
1078 /* Schedule server key regeneration alarm. */
1079 signal(SIGALRM, key_regeneration_alarm);
1080 alarm(options.key_regeneration_time);
1081 key_used = 1;
1082 }
Damien Miller37023962000-07-11 17:31:38 +10001083
1084 arc4random_stir();
1085
1086 /* Close the new socket (the child is now taking care of it). */
1087 close(newsock);
Damien Miller95def091999-11-25 00:26:21 +11001088 }
Damien Miller34132e52000-01-14 15:45:46 +11001089 /* child process check (or debug mode) */
1090 if (num_listen_socks < 0)
1091 break;
Damien Miller95def091999-11-25 00:26:21 +11001092 }
1093 }
1094
1095 /* This is the child processing a new connection. */
1096
Damien Miller5428f641999-11-25 11:54:57 +11001097 /*
1098 * Disable the key regeneration alarm. We will not regenerate the
1099 * key since we are no longer in a position to give it to anyone. We
1100 * will not restart on SIGHUP since it no longer makes sense.
1101 */
Damien Miller95def091999-11-25 00:26:21 +11001102 alarm(0);
1103 signal(SIGALRM, SIG_DFL);
1104 signal(SIGHUP, SIG_DFL);
1105 signal(SIGTERM, SIG_DFL);
1106 signal(SIGQUIT, SIG_DFL);
1107 signal(SIGCHLD, SIG_DFL);
Damien Miller4e0f5e12000-08-29 11:05:50 +11001108 signal(SIGINT, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +11001109
Damien Miller5428f641999-11-25 11:54:57 +11001110 /*
1111 * Set socket options for the connection. We want the socket to
1112 * close as fast as possible without waiting for anything. If the
1113 * connection is not a socket, these will do nothing.
1114 */
1115 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
Damien Miller95def091999-11-25 00:26:21 +11001116 linger.l_onoff = 1;
1117 linger.l_linger = 5;
1118 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1119
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001120 /* Set keepalives if requested. */
1121 if (options.keepalives &&
1122 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1123 sizeof(on)) < 0)
1124 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1125
Damien Miller5428f641999-11-25 11:54:57 +11001126 /*
1127 * Register our connection. This turns encryption off because we do
1128 * not have a key.
1129 */
Damien Miller95def091999-11-25 00:26:21 +11001130 packet_set_connection(sock_in, sock_out);
1131
1132 remote_port = get_remote_port();
1133 remote_ip = get_remote_ipaddr();
1134
1135 /* Check whether logins are denied from this host. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001136#ifdef LIBWRAP
Damien Miller34132e52000-01-14 15:45:46 +11001137 /* XXX LIBWRAP noes not know about IPv6 */
Damien Miller95def091999-11-25 00:26:21 +11001138 {
1139 struct request_info req;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001140
Ben Lindstromce89dac2001-09-12 16:58:04 +00001141 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
Damien Miller95def091999-11-25 00:26:21 +11001142 fromhost(&req);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001143
Damien Miller95def091999-11-25 00:26:21 +11001144 if (!hosts_access(&req)) {
Ben Lindstrom7de696e2001-03-29 00:45:12 +00001145 refuse(&req);
Damien Miller95def091999-11-25 00:26:21 +11001146 close(sock_in);
1147 close(sock_out);
Damien Miller95def091999-11-25 00:26:21 +11001148 }
Damien Miller34132e52000-01-14 15:45:46 +11001149/*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
Damien Miller95def091999-11-25 00:26:21 +11001150 }
Damien Miller34132e52000-01-14 15:45:46 +11001151#endif /* LIBWRAP */
Damien Miller95def091999-11-25 00:26:21 +11001152 /* Log the connection. */
1153 verbose("Connection from %.500s port %d", remote_ip, remote_port);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001154
Damien Miller5428f641999-11-25 11:54:57 +11001155 /*
1156 * We don\'t want to listen forever unless the other side
1157 * successfully authenticates itself. So we set up an alarm which is
1158 * cleared after successful authentication. A limit of zero
1159 * indicates no limit. Note that we don\'t set the alarm in debugging
1160 * mode; it is just annoying to have the server exit just when you
1161 * are about to discover the bug.
1162 */
Damien Miller95def091999-11-25 00:26:21 +11001163 signal(SIGALRM, grace_alarm_handler);
1164 if (!debug_flag)
1165 alarm(options.login_grace_time);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001166
Damien Millerb38eff82000-04-01 11:09:21 +10001167 sshd_exchange_identification(sock_in, sock_out);
Damien Miller5428f641999-11-25 11:54:57 +11001168 /*
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001169 * Check that the connection comes from a privileged port.
1170 * Rhosts-Authentication only makes sense from priviledged
Damien Miller5428f641999-11-25 11:54:57 +11001171 * programs. Of course, if the intruder has root access on his local
1172 * machine, he can connect from any port. So do not use these
1173 * authentication methods from machines that you do not trust.
1174 */
Damien Miller95def091999-11-25 00:26:21 +11001175 if (remote_port >= IPPORT_RESERVED ||
1176 remote_port < IPPORT_RESERVED / 2) {
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001177 debug("Rhosts Authentication disabled, "
Damien Miller0bc1bd82000-11-13 22:57:25 +11001178 "originating port not trusted.");
Damien Miller95def091999-11-25 00:26:21 +11001179 options.rhosts_authentication = 0;
Damien Miller95def091999-11-25 00:26:21 +11001180 }
Ben Lindstromec95ed92001-07-04 04:21:14 +00001181#if defined(KRB4) && !defined(KRB5)
Damien Miller34132e52000-01-14 15:45:46 +11001182 if (!packet_connection_is_ipv4() &&
1183 options.kerberos_authentication) {
1184 debug("Kerberos Authentication disabled, only available for IPv4.");
1185 options.kerberos_authentication = 0;
1186 }
Ben Lindstromec95ed92001-07-04 04:21:14 +00001187#endif /* KRB4 && !KRB5 */
Ben Lindstromf79aeff2001-02-10 21:27:11 +00001188#ifdef AFS
1189 /* If machine has AFS, set process authentication group. */
1190 if (k_hasafs()) {
1191 k_setpag();
1192 k_unlog();
1193 }
1194#endif /* AFS */
Damien Miller34132e52000-01-14 15:45:46 +11001195
Damien Miller95def091999-11-25 00:26:21 +11001196 packet_set_nonblocking();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001197
Damien Miller396691a2000-01-20 22:44:08 +11001198 /* perform the key exchange */
Damien Miller396691a2000-01-20 22:44:08 +11001199 /* authenticate user and start session */
Damien Millerefb4afe2000-04-12 18:45:05 +10001200 if (compat20) {
1201 do_ssh2_kex();
1202 do_authentication2();
1203 } else {
1204 do_ssh1_kex();
1205 do_authentication();
1206 }
Damien Miller95def091999-11-25 00:26:21 +11001207 /* The connection has been terminated. */
1208 verbose("Closing connection to %.100s", remote_ip);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001209
Damien Millerbeb4ba51999-12-28 15:09:35 +11001210#ifdef USE_PAM
Damien Millere72b7af1999-12-30 15:08:44 +11001211 finish_pam();
Damien Millerbeb4ba51999-12-28 15:09:35 +11001212#endif /* USE_PAM */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001213
Damien Miller95def091999-11-25 00:26:21 +11001214 packet_close();
1215 exit(0);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001216}
1217
Damien Miller95def091999-11-25 00:26:21 +11001218/*
Damien Miller396691a2000-01-20 22:44:08 +11001219 * SSH1 key exchange
Damien Miller95def091999-11-25 00:26:21 +11001220 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001221static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001222do_ssh1_kex(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001223{
Damien Miller95def091999-11-25 00:26:21 +11001224 int i, len;
Damien Miller396691a2000-01-20 22:44:08 +11001225 int plen, slen;
Damien Miller7650bc62001-01-30 09:27:26 +11001226 int rsafail = 0;
Damien Miller95def091999-11-25 00:26:21 +11001227 BIGNUM *session_key_int;
Ben Lindstrom46c16222000-12-22 01:43:59 +00001228 u_char session_key[SSH_SESSION_KEY_LENGTH];
1229 u_char cookie[8];
1230 u_int cipher_type, auth_mask, protocol_flags;
Damien Miller95def091999-11-25 00:26:21 +11001231 u_int32_t rand = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001232
Damien Miller5428f641999-11-25 11:54:57 +11001233 /*
1234 * Generate check bytes that the client must send back in the user
1235 * packet in order for it to be accepted; this is used to defy ip
1236 * spoofing attacks. Note that this only works against somebody
1237 * doing IP spoofing from a remote machine; any machine on the local
1238 * network can still see outgoing packets and catch the random
1239 * cookie. This only affects rhosts authentication, and this is one
1240 * of the reasons why it is inherently insecure.
1241 */
Damien Miller95def091999-11-25 00:26:21 +11001242 for (i = 0; i < 8; i++) {
1243 if (i % 4 == 0)
1244 rand = arc4random();
Damien Miller396691a2000-01-20 22:44:08 +11001245 cookie[i] = rand & 0xff;
Damien Miller95def091999-11-25 00:26:21 +11001246 rand >>= 8;
1247 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001248
Damien Miller5428f641999-11-25 11:54:57 +11001249 /*
1250 * Send our public key. We include in the packet 64 bits of random
1251 * data that must be matched in the reply in order to prevent IP
1252 * spoofing.
1253 */
Damien Miller95def091999-11-25 00:26:21 +11001254 packet_start(SSH_SMSG_PUBLIC_KEY);
1255 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001256 packet_put_char(cookie[i]);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001257
Damien Miller95def091999-11-25 00:26:21 +11001258 /* Store our public server RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001259 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1260 packet_put_bignum(sensitive_data.server_key->rsa->e);
1261 packet_put_bignum(sensitive_data.server_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001262
Damien Miller95def091999-11-25 00:26:21 +11001263 /* Store our public host RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001264 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1265 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1266 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001267
Damien Miller95def091999-11-25 00:26:21 +11001268 /* Put protocol flags. */
1269 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001270
Damien Miller95def091999-11-25 00:26:21 +11001271 /* Declare which ciphers we support. */
Damien Miller874d77b2000-10-14 16:23:11 +11001272 packet_put_int(cipher_mask_ssh1(0));
Damien Miller95def091999-11-25 00:26:21 +11001273
1274 /* Declare supported authentication types. */
1275 auth_mask = 0;
1276 if (options.rhosts_authentication)
1277 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1278 if (options.rhosts_rsa_authentication)
1279 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1280 if (options.rsa_authentication)
1281 auth_mask |= 1 << SSH_AUTH_RSA;
Ben Lindstromec95ed92001-07-04 04:21:14 +00001282#if defined(KRB4) || defined(KRB5)
Damien Miller95def091999-11-25 00:26:21 +11001283 if (options.kerberos_authentication)
1284 auth_mask |= 1 << SSH_AUTH_KERBEROS;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001285#endif
Ben Lindstromec95ed92001-07-04 04:21:14 +00001286#if defined(AFS) || defined(KRB5)
Damien Miller95def091999-11-25 00:26:21 +11001287 if (options.kerberos_tgt_passing)
1288 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
Ben Lindstromec95ed92001-07-04 04:21:14 +00001289#endif
1290#ifdef AFS
Damien Miller95def091999-11-25 00:26:21 +11001291 if (options.afs_token_passing)
1292 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001293#endif
Ben Lindstrom551ea372001-06-05 18:56:16 +00001294 if (options.challenge_response_authentication == 1)
Damien Miller95def091999-11-25 00:26:21 +11001295 auth_mask |= 1 << SSH_AUTH_TIS;
Damien Miller95def091999-11-25 00:26:21 +11001296 if (options.password_authentication)
1297 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1298 packet_put_int(auth_mask);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001299
Damien Miller95def091999-11-25 00:26:21 +11001300 /* Send the packet and wait for it to be sent. */
1301 packet_send();
1302 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001303
Damien Miller0bc1bd82000-11-13 22:57:25 +11001304 debug("Sent %d bit server key and %d bit host key.",
1305 BN_num_bits(sensitive_data.server_key->rsa->n),
1306 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001307
Damien Miller95def091999-11-25 00:26:21 +11001308 /* Read clients reply (cipher type and session key). */
1309 packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001310
Damien Miller50945fa1999-12-09 10:31:37 +11001311 /* Get cipher type and check whether we accept this. */
Damien Miller95def091999-11-25 00:26:21 +11001312 cipher_type = packet_get_char();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001313
Damien Miller874d77b2000-10-14 16:23:11 +11001314 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
Damien Miller50945fa1999-12-09 10:31:37 +11001315 packet_disconnect("Warning: client selects unsupported cipher.");
1316
Damien Miller95def091999-11-25 00:26:21 +11001317 /* Get check bytes from the packet. These must match those we
1318 sent earlier with the public key packet. */
1319 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001320 if (cookie[i] != packet_get_char())
Damien Miller95def091999-11-25 00:26:21 +11001321 packet_disconnect("IP Spoofing check bytes do not match.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001322
Damien Miller95def091999-11-25 00:26:21 +11001323 debug("Encryption type: %.200s", cipher_name(cipher_type));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001324
Damien Miller95def091999-11-25 00:26:21 +11001325 /* Get the encrypted integer. */
1326 session_key_int = BN_new();
1327 packet_get_bignum(session_key_int, &slen);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001328
Damien Miller95def091999-11-25 00:26:21 +11001329 protocol_flags = packet_get_int();
1330 packet_set_protocol_flags(protocol_flags);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001331
Damien Miller95def091999-11-25 00:26:21 +11001332 packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001333
Damien Miller5428f641999-11-25 11:54:57 +11001334 /*
1335 * Decrypt it using our private server key and private host key (key
1336 * with larger modulus first).
1337 */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001338 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
Damien Miller7650bc62001-01-30 09:27:26 +11001339 /* Server key has bigger modulus. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001340 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1341 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1342 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1343 get_remote_ipaddr(),
1344 BN_num_bits(sensitive_data.server_key->rsa->n),
1345 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1346 SSH_KEY_BITS_RESERVED);
Damien Miller95def091999-11-25 00:26:21 +11001347 }
Damien Miller7650bc62001-01-30 09:27:26 +11001348 if (rsa_private_decrypt(session_key_int, session_key_int,
1349 sensitive_data.server_key->rsa) <= 0)
1350 rsafail++;
1351 if (rsa_private_decrypt(session_key_int, session_key_int,
1352 sensitive_data.ssh1_host_key->rsa) <= 0)
1353 rsafail++;
Damien Miller95def091999-11-25 00:26:21 +11001354 } else {
1355 /* Host key has bigger modulus (or they are equal). */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001356 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1357 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1358 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1359 get_remote_ipaddr(),
1360 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1361 BN_num_bits(sensitive_data.server_key->rsa->n),
1362 SSH_KEY_BITS_RESERVED);
Damien Miller95def091999-11-25 00:26:21 +11001363 }
Damien Miller7650bc62001-01-30 09:27:26 +11001364 if (rsa_private_decrypt(session_key_int, session_key_int,
1365 sensitive_data.ssh1_host_key->rsa) < 0)
1366 rsafail++;
1367 if (rsa_private_decrypt(session_key_int, session_key_int,
1368 sensitive_data.server_key->rsa) < 0)
1369 rsafail++;
Damien Miller95def091999-11-25 00:26:21 +11001370 }
Damien Miller5428f641999-11-25 11:54:57 +11001371 /*
1372 * Extract session key from the decrypted integer. The key is in the
1373 * least significant 256 bits of the integer; the first byte of the
1374 * key is in the highest bits.
1375 */
Damien Miller7650bc62001-01-30 09:27:26 +11001376 if (!rsafail) {
1377 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1378 len = BN_num_bytes(session_key_int);
1379 if (len < 0 || len > sizeof(session_key)) {
1380 error("do_connection: bad session key len from %s: "
Ben Lindstrom31ca54a2001-02-09 02:11:24 +00001381 "session_key_int %d > sizeof(session_key) %lu",
1382 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
Damien Miller7650bc62001-01-30 09:27:26 +11001383 rsafail++;
1384 } else {
1385 memset(session_key, 0, sizeof(session_key));
1386 BN_bn2bin(session_key_int,
1387 session_key + sizeof(session_key) - len);
Ben Lindstromeb648a72001-03-05 06:00:29 +00001388
1389 compute_session_id(session_id, cookie,
1390 sensitive_data.ssh1_host_key->rsa->n,
1391 sensitive_data.server_key->rsa->n);
1392 /*
1393 * Xor the first 16 bytes of the session key with the
1394 * session id.
1395 */
1396 for (i = 0; i < 16; i++)
1397 session_key[i] ^= session_id[i];
Damien Miller7650bc62001-01-30 09:27:26 +11001398 }
1399 }
1400 if (rsafail) {
Ben Lindstromeb648a72001-03-05 06:00:29 +00001401 int bytes = BN_num_bytes(session_key_int);
1402 char *buf = xmalloc(bytes);
1403 MD5_CTX md;
1404
Damien Miller7650bc62001-01-30 09:27:26 +11001405 log("do_connection: generating a fake encryption key");
Ben Lindstromeb648a72001-03-05 06:00:29 +00001406 BN_bn2bin(session_key_int, buf);
1407 MD5_Init(&md);
1408 MD5_Update(&md, buf, bytes);
1409 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1410 MD5_Final(session_key, &md);
1411 MD5_Init(&md);
1412 MD5_Update(&md, session_key, 16);
1413 MD5_Update(&md, buf, bytes);
1414 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1415 MD5_Final(session_key + 16, &md);
1416 memset(buf, 0, bytes);
1417 xfree(buf);
Ben Lindstrom941ac822001-03-05 06:25:23 +00001418 for (i = 0; i < 16; i++)
1419 session_id[i] = session_key[i] ^ session_key[i + 16];
Damien Miller7650bc62001-01-30 09:27:26 +11001420 }
Ben Lindstromeb648a72001-03-05 06:00:29 +00001421 /* Destroy the private and public keys. They will no longer be needed. */
1422 destroy_sensitive_data();
1423
Damien Miller396691a2000-01-20 22:44:08 +11001424 /* Destroy the decrypted integer. It is no longer needed. */
1425 BN_clear_free(session_key_int);
1426
Damien Miller95def091999-11-25 00:26:21 +11001427 /* Set the session key. From this on all communications will be encrypted. */
1428 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001429
Damien Miller95def091999-11-25 00:26:21 +11001430 /* Destroy our copy of the session key. It is no longer needed. */
1431 memset(session_key, 0, sizeof(session_key));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001432
Damien Miller95def091999-11-25 00:26:21 +11001433 debug("Received session key; encryption turned on.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001434
Damien Miller95def091999-11-25 00:26:21 +11001435 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1436 packet_start(SSH_SMSG_SUCCESS);
1437 packet_send();
1438 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001439}
Damien Millerefb4afe2000-04-12 18:45:05 +10001440
1441/*
1442 * SSH2 key exchange: diffie-hellman-group1-sha1
1443 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001444static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001445do_ssh2_kex(void)
Damien Millerefb4afe2000-04-12 18:45:05 +10001446{
Damien Millerefb4afe2000-04-12 18:45:05 +10001447 Kex *kex;
Damien Millerefb4afe2000-04-12 18:45:05 +10001448
Damien Miller78928792000-04-12 20:17:38 +10001449 if (options.ciphers != NULL) {
Damien Miller4af51302000-04-16 11:18:38 +10001450 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
Damien Miller78928792000-04-12 20:17:38 +10001451 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1452 }
Damien Millera0ff4662001-03-30 10:49:35 +10001453 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1454 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1455 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1456 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1457
Ben Lindstrom06b33aa2001-02-15 03:01:59 +00001458 if (options.macs != NULL) {
1459 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1460 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1461 }
Damien Miller0bc1bd82000-11-13 22:57:25 +11001462 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1463
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001464 /* start key exchange */
Ben Lindstrom238abf62001-04-04 17:52:53 +00001465 kex = kex_setup(myproposal);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001466 kex->server = 1;
1467 kex->client_version_string=client_version_string;
1468 kex->server_version_string=server_version_string;
1469 kex->load_host_key=&get_hostkey_by_type;
Damien Millerefb4afe2000-04-12 18:45:05 +10001470
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001471 xxx_kex = kex;
1472
Ben Lindstrombe2cc432001-04-04 23:46:07 +00001473 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
Damien Miller874d77b2000-10-14 16:23:11 +11001474
Ben Lindstrom2d90e002001-04-04 02:00:54 +00001475 session_id2 = kex->session_id;
1476 session_id2_len = kex->session_id_len;
1477
Damien Miller874d77b2000-10-14 16:23:11 +11001478#ifdef DEBUG_KEXDH
1479 /* send 1st encrypted/maced/compressed message */
1480 packet_start(SSH2_MSG_IGNORE);
1481 packet_put_cstring("markus");
1482 packet_send();
1483 packet_write_wait();
1484#endif
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001485 debug("KEX done");
Damien Millerefb4afe2000-04-12 18:45:05 +10001486}