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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 Miller9f0f5c62001-12-21 14:45:46 +110043RCSID("$OpenBSD: sshd.c,v 1.217 2001/12/19 07:18:56 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"
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +000073#include "dispatch.h"
Ben Lindstrom1bae4042001-10-03 17:46:39 +000074#include "channels.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100075
76#ifdef LIBWRAP
77#include <tcpd.h>
78#include <syslog.h>
79int allow_severity = LOG_INFO;
80int deny_severity = LOG_WARNING;
81#endif /* LIBWRAP */
82
83#ifndef O_NOCTTY
84#define O_NOCTTY 0
85#endif
86
Ben Lindstrom49a79c02000-11-17 03:47:20 +000087#ifdef HAVE___PROGNAME
88extern char *__progname;
89#else
90char *__progname;
91#endif
92
Damien Millerd4a8b7e1999-10-27 13:42:43 +100093/* Server configuration options. */
94ServerOptions options;
95
96/* Name of the server configuration file. */
Ben Lindstrom226cfa02001-01-22 05:34:40 +000097char *config_file_name = _PATH_SERVER_CONFIG_FILE;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100098
Damien Miller4af51302000-04-16 11:18:38 +100099/*
Damien Miller34132e52000-01-14 15:45:46 +1100100 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
101 * Default value is AF_UNSPEC means both IPv4 and IPv6.
102 */
Damien Miller7d80e342000-01-19 14:36:49 +1100103#ifdef IPV4_DEFAULT
104int IPv4or6 = AF_INET;
105#else
Damien Miller34132e52000-01-14 15:45:46 +1100106int IPv4or6 = AF_UNSPEC;
Damien Miller7d80e342000-01-19 14:36:49 +1100107#endif
Damien Miller34132e52000-01-14 15:45:46 +1100108
Damien Miller95def091999-11-25 00:26:21 +1100109/*
110 * Debug mode flag. This can be set on the command line. If debug
111 * mode is enabled, extra debugging output will be sent to the system
112 * log, the daemon will not go to background, and will exit after processing
113 * the first connection.
114 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000115int debug_flag = 0;
116
Ben Lindstrom794325a2001-08-06 21:09:07 +0000117/* Flag indicating that the daemon should only test the configuration and keys. */
118int test_flag = 0;
119
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000120/* Flag indicating that the daemon is being started from inetd. */
121int inetd_flag = 0;
122
Ben Lindstromc72745a2000-12-02 19:03:54 +0000123/* Flag indicating that sshd should not detach and become a daemon. */
124int no_daemon_flag = 0;
125
Damien Miller5ce662a1999-11-11 17:57:39 +1100126/* debug goes to stderr unless inetd_flag is set */
127int log_stderr = 0;
128
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000129/* Saved arguments to main(). */
130char **saved_argv;
Damien Millerb8c656e2000-06-28 15:22:41 +1000131int saved_argc;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000132
Damien Miller5428f641999-11-25 11:54:57 +1100133/*
Damien Miller34132e52000-01-14 15:45:46 +1100134 * The sockets that the server is listening; this is used in the SIGHUP
135 * signal handler.
Damien Miller5428f641999-11-25 11:54:57 +1100136 */
Damien Miller34132e52000-01-14 15:45:46 +1100137#define MAX_LISTEN_SOCKS 16
138int listen_socks[MAX_LISTEN_SOCKS];
139int num_listen_socks = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000140
Damien Miller5428f641999-11-25 11:54:57 +1100141/*
142 * the client's version string, passed by sshd2 in compat mode. if != NULL,
143 * sshd will skip the version-number exchange
144 */
Damien Miller95def091999-11-25 00:26:21 +1100145char *client_version_string = NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000146char *server_version_string = NULL;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000147
Ben Lindstrom8ac91062001-04-04 17:57:54 +0000148/* for rekeying XXX fixme */
149Kex *xxx_kex;
150
Damien Miller5428f641999-11-25 11:54:57 +1100151/*
152 * Any really sensitive data in the application is contained in this
153 * structure. The idea is that this structure could be locked into memory so
154 * that the pages do not get written into swap. However, there are some
155 * problems. The private key contains BIGNUMs, and we do not (in principle)
156 * have access to the internals of them, and locking just the structure is
157 * not very useful. Currently, memory locking is not implemented.
158 */
Damien Miller95def091999-11-25 00:26:21 +1100159struct {
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000160 Key *server_key; /* ephemeral server key */
Damien Miller0bc1bd82000-11-13 22:57:25 +1100161 Key *ssh1_host_key; /* ssh1 host key */
162 Key **host_keys; /* all private host keys */
163 int have_ssh1_key;
164 int have_ssh2_key;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000165 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000166} sensitive_data;
167
Damien Miller5428f641999-11-25 11:54:57 +1100168/*
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000169 * Flag indicating whether the RSA server key needs to be regenerated.
170 * Is set in the SIGALRM handler and cleared when the key is regenerated.
Damien Miller5428f641999-11-25 11:54:57 +1100171 */
Ben Lindstrom5e71c542001-12-06 16:48:14 +0000172static volatile sig_atomic_t key_do_regen = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000173
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000174/* This is set to true when a signal is received. */
Ben Lindstrom5e71c542001-12-06 16:48:14 +0000175static volatile sig_atomic_t received_sighup = 0;
176static volatile sig_atomic_t received_sigterm = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000177
Damien Millerb38eff82000-04-01 11:09:21 +1000178/* session identifier, used by RSA-auth */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000179u_char session_id[16];
Damien Millerb38eff82000-04-01 11:09:21 +1000180
Damien Millereba71ba2000-04-29 23:57:08 +1000181/* same for ssh2 */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000182u_char *session_id2 = NULL;
Damien Millereba71ba2000-04-29 23:57:08 +1000183int session_id2_len = 0;
184
Damien Miller942da032000-08-18 13:59:06 +1000185/* record remote hostname or ip */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000186u_int utmp_len = MAXHOSTNAMELEN;
Damien Miller942da032000-08-18 13:59:06 +1000187
Ben Lindstromd84df982001-12-06 16:35:40 +0000188/* options.max_startup sized array of fd ints */
189int *startup_pipes = NULL;
190int startup_pipe; /* in child */
191
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000192/* Prototypes for various functions defined later in this file. */
Ben Lindstrombba81212001-06-25 05:01:22 +0000193void destroy_sensitive_data(void);
Damien Miller98c7ad62000-03-09 21:27:49 +1100194
Ben Lindstrombba81212001-06-25 05:01:22 +0000195static void do_ssh1_kex(void);
196static void do_ssh2_kex(void);
Damien Miller874d77b2000-10-14 16:23:11 +1100197
Damien Miller98c7ad62000-03-09 21:27:49 +1100198/*
Damien Miller34132e52000-01-14 15:45:46 +1100199 * Close all listening sockets
200 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000201static void
Damien Miller34132e52000-01-14 15:45:46 +1100202close_listen_socks(void)
203{
204 int i;
205 for (i = 0; i < num_listen_socks; i++)
206 close(listen_socks[i]);
207 num_listen_socks = -1;
208}
209
Ben Lindstromd84df982001-12-06 16:35:40 +0000210static void
211close_startup_pipes(void)
212{
213 int i;
214 if (startup_pipes)
215 for (i = 0; i < options.max_startups; i++)
216 if (startup_pipes[i] != -1)
217 close(startup_pipes[i]);
218}
219
Damien Miller34132e52000-01-14 15:45:46 +1100220/*
Damien Miller95def091999-11-25 00:26:21 +1100221 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
222 * the effect is to reread the configuration file (and to regenerate
223 * the server key).
224 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000225static void
Damien Miller95def091999-11-25 00:26:21 +1100226sighup_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000227{
Ben Lindstrom07958482001-12-06 16:19:01 +0000228 int save_errno = errno;
229
Damien Miller95def091999-11-25 00:26:21 +1100230 received_sighup = 1;
231 signal(SIGHUP, sighup_handler);
Ben Lindstrom07958482001-12-06 16:19:01 +0000232 errno = save_errno;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000233}
234
Damien Miller95def091999-11-25 00:26:21 +1100235/*
236 * Called from the main program after receiving SIGHUP.
237 * Restarts the server.
238 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000239static void
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000240sighup_restart(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000241{
Damien Miller95def091999-11-25 00:26:21 +1100242 log("Received SIGHUP; restarting.");
Damien Miller34132e52000-01-14 15:45:46 +1100243 close_listen_socks();
Ben Lindstromd84df982001-12-06 16:35:40 +0000244 close_startup_pipes();
Damien Miller95def091999-11-25 00:26:21 +1100245 execv(saved_argv[0], saved_argv);
Kevin Stevesec84dc12000-12-13 17:45:15 +0000246 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100247 exit(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000248}
249
Damien Miller95def091999-11-25 00:26:21 +1100250/*
251 * Generic signal handler for terminating signals in the master daemon.
Damien Miller95def091999-11-25 00:26:21 +1100252 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000253static void
Damien Miller95def091999-11-25 00:26:21 +1100254sigterm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000255{
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000256 received_sigterm = sig;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000257}
258
Damien Miller95def091999-11-25 00:26:21 +1100259/*
260 * SIGCHLD handler. This is called whenever a child dies. This will then
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000261 * reap any zombies left by exited children.
Damien Miller95def091999-11-25 00:26:21 +1100262 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000263static void
Damien Miller95def091999-11-25 00:26:21 +1100264main_sigchld_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000265{
Damien Miller95def091999-11-25 00:26:21 +1100266 int save_errno = errno;
267 int status;
Damien Miller431f66b1999-11-21 18:31:57 +1100268
Damien Miller95def091999-11-25 00:26:21 +1100269 while (waitpid(-1, &status, WNOHANG) > 0)
270 ;
Damien Miller431f66b1999-11-21 18:31:57 +1100271
Damien Miller95def091999-11-25 00:26:21 +1100272 signal(SIGCHLD, main_sigchld_handler);
273 errno = save_errno;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000274}
275
Damien Miller95def091999-11-25 00:26:21 +1100276/*
277 * Signal handler for the alarm after the login grace period has expired.
278 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000279static void
Damien Miller95def091999-11-25 00:26:21 +1100280grace_alarm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000281{
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000282 /* XXX no idea how fix this signal handler */
283
Damien Miller95def091999-11-25 00:26:21 +1100284 /* Close the connection. */
285 packet_close();
286
287 /* Log error and exit. */
288 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000289}
290
Damien Miller95def091999-11-25 00:26:21 +1100291/*
Damien Miller95def091999-11-25 00:26:21 +1100292 * Signal handler for the key regeneration alarm. Note that this
293 * alarm only occurs in the daemon waiting for connections, and it does not
294 * do anything with the private key or random state before forking.
295 * Thus there should be no concurrency control/asynchronous execution
296 * problems.
297 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000298static void
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000299generate_ephemeral_server_key(void)
Damien Miller0bc1bd82000-11-13 22:57:25 +1100300{
Ben Lindstromeb648a72001-03-05 06:00:29 +0000301 u_int32_t rand = 0;
302 int i;
303
Ben Lindstroma3700052001-04-05 23:26:32 +0000304 verbose("Generating %s%d bit RSA key.",
Damien Millerff75ac42001-03-30 10:50:32 +1000305 sensitive_data.server_key ? "new " : "", options.server_key_bits);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100306 if (sensitive_data.server_key != NULL)
307 key_free(sensitive_data.server_key);
Ben Lindstroma3700052001-04-05 23:26:32 +0000308 sensitive_data.server_key = key_generate(KEY_RSA1,
Damien Millerff75ac42001-03-30 10:50:32 +1000309 options.server_key_bits);
310 verbose("RSA key generation complete.");
Ben Lindstromeb648a72001-03-05 06:00:29 +0000311
312 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
313 if (i % 4 == 0)
314 rand = arc4random();
315 sensitive_data.ssh1_cookie[i] = rand & 0xff;
316 rand >>= 8;
317 }
318 arc4random_stir();
Damien Miller0bc1bd82000-11-13 22:57:25 +1100319}
Ben Lindstrom2f959b42001-01-11 06:20:23 +0000320
Ben Lindstrombba81212001-06-25 05:01:22 +0000321static void
Damien Miller95def091999-11-25 00:26:21 +1100322key_regeneration_alarm(int sig)
323{
324 int save_errno = errno;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000325 signal(SIGALRM, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +1100326 errno = save_errno;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000327 key_do_regen = 1;
Damien Miller95def091999-11-25 00:26:21 +1100328}
329
Ben Lindstrombba81212001-06-25 05:01:22 +0000330static void
Damien Millerb38eff82000-04-01 11:09:21 +1000331sshd_exchange_identification(int sock_in, int sock_out)
332{
Damien Miller78928792000-04-12 20:17:38 +1000333 int i, mismatch;
Damien Millerb38eff82000-04-01 11:09:21 +1000334 int remote_major, remote_minor;
Damien Miller78928792000-04-12 20:17:38 +1000335 int major, minor;
Damien Millerb38eff82000-04-01 11:09:21 +1000336 char *s;
337 char buf[256]; /* Must not be larger than remote_version. */
338 char remote_version[256]; /* Must be at least as big as buf. */
339
Damien Miller78928792000-04-12 20:17:38 +1000340 if ((options.protocol & SSH_PROTO_1) &&
341 (options.protocol & SSH_PROTO_2)) {
342 major = PROTOCOL_MAJOR_1;
343 minor = 99;
344 } else if (options.protocol & SSH_PROTO_2) {
345 major = PROTOCOL_MAJOR_2;
346 minor = PROTOCOL_MINOR_2;
347 } else {
348 major = PROTOCOL_MAJOR_1;
349 minor = PROTOCOL_MINOR_1;
350 }
351 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
Damien Millerb38eff82000-04-01 11:09:21 +1000352 server_version_string = xstrdup(buf);
353
354 if (client_version_string == NULL) {
355 /* Send our protocol version identification. */
356 if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
357 != strlen(server_version_string)) {
Damien Millere4a0ff42001-11-12 11:06:54 +1100358 log("Could not write ident string to %s", get_remote_ipaddr());
Damien Millerb38eff82000-04-01 11:09:21 +1000359 fatal_cleanup();
360 }
361
Ben Lindstrom5393f932001-02-15 03:17:13 +0000362 /* Read other side's version identification. */
Ben Lindstroma3700052001-04-05 23:26:32 +0000363 memset(buf, 0, sizeof(buf));
Damien Millerb38eff82000-04-01 11:09:21 +1000364 for (i = 0; i < sizeof(buf) - 1; i++) {
Damien Millerbf7f4662000-06-23 10:16:38 +1000365 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
Damien Millere4a0ff42001-11-12 11:06:54 +1100366 log("Did not receive identification string from %s",
Ben Lindstroma9a29e12001-02-20 01:20:47 +0000367 get_remote_ipaddr());
Damien Millerb38eff82000-04-01 11:09:21 +1000368 fatal_cleanup();
369 }
370 if (buf[i] == '\r') {
Ben Lindstrom69d8c072001-03-22 22:45:33 +0000371 buf[i] = 0;
Damien Miller874d77b2000-10-14 16:23:11 +1100372 /* Kludge for F-Secure Macintosh < 1.0.2 */
373 if (i == 12 &&
374 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
375 break;
Damien Millerb38eff82000-04-01 11:09:21 +1000376 continue;
Damien Millerb38eff82000-04-01 11:09:21 +1000377 }
378 if (buf[i] == '\n') {
Ben Lindstrom69d8c072001-03-22 22:45:33 +0000379 buf[i] = 0;
Damien Millerb38eff82000-04-01 11:09:21 +1000380 break;
381 }
382 }
383 buf[sizeof(buf) - 1] = 0;
384 client_version_string = xstrdup(buf);
385 }
386
387 /*
388 * Check that the versions match. In future this might accept
389 * several versions and set appropriate flags to handle them.
390 */
391 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
392 &remote_major, &remote_minor, remote_version) != 3) {
Damien Miller4af51302000-04-16 11:18:38 +1000393 s = "Protocol mismatch.\n";
Damien Millerb38eff82000-04-01 11:09:21 +1000394 (void) atomicio(write, sock_out, s, strlen(s));
395 close(sock_in);
396 close(sock_out);
397 log("Bad protocol version identification '%.100s' from %s",
398 client_version_string, get_remote_ipaddr());
399 fatal_cleanup();
400 }
401 debug("Client protocol version %d.%d; client software version %.100s",
Damien Miller9f0f5c62001-12-21 14:45:46 +1100402 remote_major, remote_minor, remote_version);
Damien Millerb38eff82000-04-01 11:09:21 +1000403
Damien Millerefb4afe2000-04-12 18:45:05 +1000404 compat_datafellows(remote_version);
405
Damien Miller27dbe6f2001-03-19 22:36:20 +1100406 if (datafellows & SSH_BUG_SCANNER) {
407 log("scanned from %s with %s. Don't panic.",
408 get_remote_ipaddr(), client_version_string);
409 fatal_cleanup();
410 }
411
Damien Miller78928792000-04-12 20:17:38 +1000412 mismatch = 0;
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000413 switch (remote_major) {
Damien Millerb38eff82000-04-01 11:09:21 +1000414 case 1:
Damien Millereba71ba2000-04-29 23:57:08 +1000415 if (remote_minor == 99) {
416 if (options.protocol & SSH_PROTO_2)
417 enable_compat20();
418 else
419 mismatch = 1;
420 break;
421 }
Damien Miller78928792000-04-12 20:17:38 +1000422 if (!(options.protocol & SSH_PROTO_1)) {
423 mismatch = 1;
424 break;
425 }
Damien Millerb38eff82000-04-01 11:09:21 +1000426 if (remote_minor < 3) {
Damien Miller37023962000-07-11 17:31:38 +1000427 packet_disconnect("Your ssh version is too old and "
Damien Millerb38eff82000-04-01 11:09:21 +1000428 "is no longer supported. Please install a newer version.");
429 } else if (remote_minor == 3) {
430 /* note that this disables agent-forwarding */
431 enable_compat13();
432 }
Damien Miller78928792000-04-12 20:17:38 +1000433 break;
Damien Millerefb4afe2000-04-12 18:45:05 +1000434 case 2:
Damien Miller78928792000-04-12 20:17:38 +1000435 if (options.protocol & SSH_PROTO_2) {
Damien Millerefb4afe2000-04-12 18:45:05 +1000436 enable_compat20();
437 break;
438 }
439 /* FALLTHROUGH */
Damien Miller4af51302000-04-16 11:18:38 +1000440 default:
Damien Miller78928792000-04-12 20:17:38 +1000441 mismatch = 1;
Damien Millerb38eff82000-04-01 11:09:21 +1000442 break;
443 }
Damien Millerefb4afe2000-04-12 18:45:05 +1000444 chop(server_version_string);
Damien Miller78928792000-04-12 20:17:38 +1000445 debug("Local version string %.200s", server_version_string);
446
447 if (mismatch) {
448 s = "Protocol major versions differ.\n";
449 (void) atomicio(write, sock_out, s, strlen(s));
450 close(sock_in);
451 close(sock_out);
452 log("Protocol major versions differ for %s: %.200s vs. %.200s",
453 get_remote_ipaddr(),
454 server_version_string, client_version_string);
455 fatal_cleanup();
456 }
Damien Millereba71ba2000-04-29 23:57:08 +1000457}
458
459
Damien Miller0bc1bd82000-11-13 22:57:25 +1100460/* Destroy the host and server keys. They will no longer be needed. */
Damien Millereba71ba2000-04-29 23:57:08 +1000461void
462destroy_sensitive_data(void)
463{
Damien Miller0bc1bd82000-11-13 22:57:25 +1100464 int i;
465
466 if (sensitive_data.server_key) {
467 key_free(sensitive_data.server_key);
468 sensitive_data.server_key = NULL;
469 }
Damien Miller9f0f5c62001-12-21 14:45:46 +1100470 for (i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100471 if (sensitive_data.host_keys[i]) {
472 key_free(sensitive_data.host_keys[i]);
473 sensitive_data.host_keys[i] = NULL;
474 }
475 }
476 sensitive_data.ssh1_host_key = NULL;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000477 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100478}
Damien Miller0bc1bd82000-11-13 22:57:25 +1100479
Ben Lindstrombba81212001-06-25 05:01:22 +0000480static char *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100481list_hostkey_types(void)
482{
483 static char buf[1024];
484 int i;
485 buf[0] = '\0';
Damien Miller9f0f5c62001-12-21 14:45:46 +1100486 for (i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100487 Key *key = sensitive_data.host_keys[i];
488 if (key == NULL)
489 continue;
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000490 switch (key->type) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100491 case KEY_RSA:
492 case KEY_DSA:
493 strlcat(buf, key_ssh_name(key), sizeof buf);
494 strlcat(buf, ",", sizeof buf);
495 break;
496 }
497 }
498 i = strlen(buf);
499 if (i > 0 && buf[i-1] == ',')
500 buf[i-1] = '\0';
501 debug("list_hostkey_types: %s", buf);
502 return buf;
503}
504
Ben Lindstrombba81212001-06-25 05:01:22 +0000505static Key *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100506get_hostkey_by_type(int type)
507{
508 int i;
Damien Miller9f0f5c62001-12-21 14:45:46 +1100509 for (i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100510 Key *key = sensitive_data.host_keys[i];
511 if (key != NULL && key->type == type)
512 return key;
513 }
514 return NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000515}
516
Damien Miller942da032000-08-18 13:59:06 +1000517/*
518 * returns 1 if connection should be dropped, 0 otherwise.
519 * dropping starts at connection #max_startups_begin with a probability
520 * of (max_startups_rate/100). the probability increases linearly until
521 * all connections are dropped for startups > max_startups
522 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000523static int
Damien Miller942da032000-08-18 13:59:06 +1000524drop_connection(int startups)
525{
526 double p, r;
527
528 if (startups < options.max_startups_begin)
529 return 0;
530 if (startups >= options.max_startups)
531 return 1;
532 if (options.max_startups_rate == 100)
533 return 1;
534
535 p = 100 - options.max_startups_rate;
536 p *= startups - options.max_startups_begin;
537 p /= (double) (options.max_startups - options.max_startups_begin);
538 p += options.max_startups_rate;
539 p /= 100.0;
540 r = arc4random() / (double) UINT_MAX;
541
542 debug("drop_connection: p %g, r %g", p, r);
543 return (r < p) ? 1 : 0;
544}
545
Ben Lindstromade03f62001-12-06 18:22:17 +0000546static void
547usage(void)
548{
549 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
550 fprintf(stderr, "Usage: %s [options]\n", __progname);
551 fprintf(stderr, "Options:\n");
552 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
553 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
554 fprintf(stderr, " -i Started from inetd\n");
555 fprintf(stderr, " -D Do not fork into daemon mode\n");
556 fprintf(stderr, " -t Only test configuration file and keys\n");
557 fprintf(stderr, " -q Quiet (no logging)\n");
558 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
559 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
560 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
561 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
562 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
563 _PATH_HOST_KEY_FILE);
564 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
565 fprintf(stderr, " -4 Use IPv4 only\n");
566 fprintf(stderr, " -6 Use IPv6 only\n");
567 fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n");
568 exit(1);
569}
570
Damien Miller95def091999-11-25 00:26:21 +1100571/*
572 * Main program for the daemon.
573 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000574int
575main(int ac, char **av)
576{
Damien Miller95def091999-11-25 00:26:21 +1100577 extern char *optarg;
578 extern int optind;
Damien Miller37023962000-07-11 17:31:38 +1000579 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
Damien Miller166fca82000-04-20 07:42:21 +1000580 pid_t pid;
Damien Miller34132e52000-01-14 15:45:46 +1100581 socklen_t fromlen;
Damien Miller34132e52000-01-14 15:45:46 +1100582 fd_set *fdset;
583 struct sockaddr_storage from;
Damien Miller95def091999-11-25 00:26:21 +1100584 const char *remote_ip;
585 int remote_port;
Damien Miller95def091999-11-25 00:26:21 +1100586 FILE *f;
587 struct linger linger;
Damien Miller34132e52000-01-14 15:45:46 +1100588 struct addrinfo *ai;
589 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
590 int listen_sock, maxfd;
Damien Miller37023962000-07-11 17:31:38 +1000591 int startup_p[2];
592 int startups = 0;
Ben Lindstromd0fca422001-03-26 13:44:06 +0000593 Key *key;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000594 int ret, key_used = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000595
Ben Lindstrom49a79c02000-11-17 03:47:20 +0000596 __progname = get_progname(av[0]);
Damien Millerf9b625c2000-07-09 22:42:32 +1000597 init_rng();
598
Kevin Stevesec84dc12000-12-13 17:45:15 +0000599 /* Save argv. */
Damien Millerb8c656e2000-06-28 15:22:41 +1000600 saved_argc = ac;
Damien Miller95def091999-11-25 00:26:21 +1100601 saved_argv = av;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000602
Damien Miller95def091999-11-25 00:26:21 +1100603 /* Initialize configuration options to their default values. */
604 initialize_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000605
Damien Miller95def091999-11-25 00:26:21 +1100606 /* Parse command-line arguments. */
Ben Lindstromade03f62001-12-06 18:22:17 +0000607 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) {
Damien Miller95def091999-11-25 00:26:21 +1100608 switch (opt) {
Damien Miller34132e52000-01-14 15:45:46 +1100609 case '4':
610 IPv4or6 = AF_INET;
611 break;
612 case '6':
613 IPv4or6 = AF_INET6;
614 break;
Damien Miller95def091999-11-25 00:26:21 +1100615 case 'f':
616 config_file_name = optarg;
617 break;
618 case 'd':
Damien Millere4340be2000-09-16 13:29:08 +1100619 if (0 == debug_flag) {
620 debug_flag = 1;
621 options.log_level = SYSLOG_LEVEL_DEBUG1;
622 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
623 options.log_level++;
624 } else {
625 fprintf(stderr, "Too high debugging level.\n");
626 exit(1);
627 }
Damien Miller95def091999-11-25 00:26:21 +1100628 break;
Ben Lindstromc72745a2000-12-02 19:03:54 +0000629 case 'D':
630 no_daemon_flag = 1;
631 break;
Ben Lindstrom9fce9f02001-04-11 23:10:09 +0000632 case 'e':
633 log_stderr = 1;
634 break;
Damien Miller95def091999-11-25 00:26:21 +1100635 case 'i':
636 inetd_flag = 1;
637 break;
638 case 'Q':
Ben Lindstromd5390202001-01-29 08:07:43 +0000639 /* ignored */
Damien Miller95def091999-11-25 00:26:21 +1100640 break;
641 case 'q':
642 options.log_level = SYSLOG_LEVEL_QUIET;
643 break;
644 case 'b':
645 options.server_key_bits = atoi(optarg);
646 break;
647 case 'p':
Damien Miller34132e52000-01-14 15:45:46 +1100648 options.ports_from_cmdline = 1;
Damien Millere4340be2000-09-16 13:29:08 +1100649 if (options.num_ports >= MAX_PORTS) {
650 fprintf(stderr, "too many ports.\n");
651 exit(1);
652 }
Ben Lindstrom19066a12001-04-12 23:39:26 +0000653 options.ports[options.num_ports++] = a2port(optarg);
654 if (options.ports[options.num_ports-1] == 0) {
655 fprintf(stderr, "Bad port number.\n");
656 exit(1);
657 }
Damien Miller95def091999-11-25 00:26:21 +1100658 break;
659 case 'g':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000660 if ((options.login_grace_time = convtime(optarg)) == -1) {
661 fprintf(stderr, "Invalid login grace time.\n");
662 exit(1);
663 }
Damien Miller95def091999-11-25 00:26:21 +1100664 break;
665 case 'k':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000666 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
667 fprintf(stderr, "Invalid key regeneration interval.\n");
668 exit(1);
669 }
Damien Miller95def091999-11-25 00:26:21 +1100670 break;
671 case 'h':
Damien Miller0bc1bd82000-11-13 22:57:25 +1100672 if (options.num_host_key_files >= MAX_HOSTKEYS) {
673 fprintf(stderr, "too many host keys.\n");
674 exit(1);
675 }
676 options.host_key_files[options.num_host_key_files++] = optarg;
Damien Miller95def091999-11-25 00:26:21 +1100677 break;
678 case 'V':
679 client_version_string = optarg;
680 /* only makes sense with inetd_flag, i.e. no listen() */
681 inetd_flag = 1;
682 break;
Ben Lindstrom794325a2001-08-06 21:09:07 +0000683 case 't':
684 test_flag = 1;
685 break;
Damien Miller942da032000-08-18 13:59:06 +1000686 case 'u':
687 utmp_len = atoi(optarg);
688 break;
Ben Lindstromade03f62001-12-06 18:22:17 +0000689 case 'o':
Damien Miller9f0f5c62001-12-21 14:45:46 +1100690 if (process_server_config_line(&options, optarg,
Ben Lindstromade03f62001-12-06 18:22:17 +0000691 "command-line", 0) != 0)
Damien Miller9f0f5c62001-12-21 14:45:46 +1100692 exit(1);
Ben Lindstromade03f62001-12-06 18:22:17 +0000693 break;
Damien Miller95def091999-11-25 00:26:21 +1100694 case '?':
695 default:
Ben Lindstromade03f62001-12-06 18:22:17 +0000696 usage();
697 break;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000698 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000699 }
Ben Lindstrom425fb022001-03-29 00:31:20 +0000700 SSLeay_add_all_algorithms();
Ben Lindstrom908afed2001-10-03 17:34:59 +0000701 channel_set_af(IPv4or6);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000702
Damien Miller34132e52000-01-14 15:45:46 +1100703 /*
704 * Force logging to stderr until we have loaded the private host
705 * key (unless started from inetd)
706 */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000707 log_init(__progname,
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000708 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
Damien Miller34132e52000-01-14 15:45:46 +1100709 options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
Ben Lindstromd5390202001-01-29 08:07:43 +0000710 !inetd_flag);
Damien Miller34132e52000-01-14 15:45:46 +1100711
Ben Lindstrom6db66ff2001-08-06 23:29:16 +0000712#ifdef _CRAY
713 /* Cray can define user privs drop all prives now!
714 * Not needed on PRIV_SU systems!
715 */
716 drop_cray_privs();
717#endif
718
Damien Miller60bc5172001-03-19 09:38:15 +1100719 seed_rng();
720
Damien Miller95def091999-11-25 00:26:21 +1100721 /* Read server configuration options from the configuration file. */
722 read_server_config(&options, config_file_name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000723
Damien Miller95def091999-11-25 00:26:21 +1100724 /* Fill in default values for those options not explicitly set. */
725 fill_default_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000726
Damien Miller95def091999-11-25 00:26:21 +1100727 /* Check that there are no remaining arguments. */
728 if (optind < ac) {
729 fprintf(stderr, "Extra argument %s.\n", av[optind]);
730 exit(1);
731 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000732
Damien Miller95def091999-11-25 00:26:21 +1100733 debug("sshd version %.100s", SSH_VERSION);
Damien Miller2ccf6611999-11-15 15:25:10 +1100734
Damien Miller0bc1bd82000-11-13 22:57:25 +1100735 /* load private host keys */
736 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
Damien Miller9f0f5c62001-12-21 14:45:46 +1100737 for (i = 0; i < options.num_host_key_files; i++)
Ben Lindstrom46c16222000-12-22 01:43:59 +0000738 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100739 sensitive_data.server_key = NULL;
740 sensitive_data.ssh1_host_key = NULL;
741 sensitive_data.have_ssh1_key = 0;
742 sensitive_data.have_ssh2_key = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000743
Damien Miller9f0f5c62001-12-21 14:45:46 +1100744 for (i = 0; i < options.num_host_key_files; i++) {
Ben Lindstromd0fca422001-03-26 13:44:06 +0000745 key = key_load_private(options.host_key_files[i], "", NULL);
746 sensitive_data.host_keys[i] = key;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100747 if (key == NULL) {
Ben Lindstrom15f33862001-04-16 02:00:02 +0000748 error("Could not load host key: %s",
749 options.host_key_files[i]);
Ben Lindstromd0fca422001-03-26 13:44:06 +0000750 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100751 continue;
752 }
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000753 switch (key->type) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100754 case KEY_RSA1:
755 sensitive_data.ssh1_host_key = key;
756 sensitive_data.have_ssh1_key = 1;
757 break;
758 case KEY_RSA:
759 case KEY_DSA:
760 sensitive_data.have_ssh2_key = 1;
761 break;
762 }
Ben Lindstromd0fca422001-03-26 13:44:06 +0000763 debug("private host key: #%d type %d %s", i, key->type,
764 key_type(key));
Damien Miller0bc1bd82000-11-13 22:57:25 +1100765 }
766 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
767 log("Disabling protocol version 1. Could not load host key");
Damien Millereba71ba2000-04-29 23:57:08 +1000768 options.protocol &= ~SSH_PROTO_1;
769 }
Damien Miller0bc1bd82000-11-13 22:57:25 +1100770 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
771 log("Disabling protocol version 2. Could not load host key");
772 options.protocol &= ~SSH_PROTO_2;
Damien Millereba71ba2000-04-29 23:57:08 +1000773 }
Kevin Stevesadf74cd2001-02-05 14:22:50 +0000774 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
Ben Lindstrom6df8ef42001-03-05 07:47:23 +0000775 log("sshd: no hostkeys available -- exiting.");
Damien Miller95def091999-11-25 00:26:21 +1100776 exit(1);
777 }
Damien Miller95def091999-11-25 00:26:21 +1100778
Damien Millereba71ba2000-04-29 23:57:08 +1000779 /* Check certain values for sanity. */
780 if (options.protocol & SSH_PROTO_1) {
781 if (options.server_key_bits < 512 ||
782 options.server_key_bits > 32768) {
783 fprintf(stderr, "Bad server key size.\n");
784 exit(1);
785 }
786 /*
787 * Check that server and host key lengths differ sufficiently. This
788 * is necessary to make double encryption work with rsaref. Oh, I
789 * hate software patents. I dont know if this can go? Niels
790 */
791 if (options.server_key_bits >
Damien Miller0bc1bd82000-11-13 22:57:25 +1100792 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
Damien Millereba71ba2000-04-29 23:57:08 +1000793 options.server_key_bits <
Damien Miller0bc1bd82000-11-13 22:57:25 +1100794 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
Damien Millereba71ba2000-04-29 23:57:08 +1000795 options.server_key_bits =
Damien Miller0bc1bd82000-11-13 22:57:25 +1100796 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
Damien Millereba71ba2000-04-29 23:57:08 +1000797 debug("Forcing server key to %d bits to make it differ from host key.",
798 options.server_key_bits);
799 }
800 }
801
Ben Lindstrom794325a2001-08-06 21:09:07 +0000802 /* Configuration looks good, so exit if in test mode. */
803 if (test_flag)
804 exit(0);
805
Damien Miller78315eb2000-09-29 23:01:36 +1100806#ifdef HAVE_SCO_PROTECTED_PW
807 (void) set_auth_parameters(ac, av);
808#endif
809
Damien Millereba71ba2000-04-29 23:57:08 +1000810 /* Initialize the log (it is reinitialized below in case we forked). */
Damien Miller95def091999-11-25 00:26:21 +1100811 if (debug_flag && !inetd_flag)
812 log_stderr = 1;
Kevin Stevesec84dc12000-12-13 17:45:15 +0000813 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +1100814
Damien Millereba71ba2000-04-29 23:57:08 +1000815 /*
816 * If not in debugging mode, and not started from inetd, disconnect
817 * from the controlling terminal, and fork. The original process
818 * exits.
819 */
Ben Lindstromc72745a2000-12-02 19:03:54 +0000820 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
Damien Miller95def091999-11-25 00:26:21 +1100821#ifdef TIOCNOTTY
822 int fd;
823#endif /* TIOCNOTTY */
824 if (daemon(0, 0) < 0)
825 fatal("daemon() failed: %.200s", strerror(errno));
826
827 /* Disconnect from the controlling tty. */
828#ifdef TIOCNOTTY
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000829 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
Damien Miller95def091999-11-25 00:26:21 +1100830 if (fd >= 0) {
831 (void) ioctl(fd, TIOCNOTTY, NULL);
832 close(fd);
833 }
834#endif /* TIOCNOTTY */
835 }
836 /* Reinitialize the log (because of the fork above). */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000837 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +1100838
Damien Miller95def091999-11-25 00:26:21 +1100839 /* Initialize the random number generator. */
840 arc4random_stir();
841
842 /* Chdir to the root directory so that the current disk can be
843 unmounted if desired. */
844 chdir("/");
Damien Miller9f0f5c62001-12-21 14:45:46 +1100845
Ben Lindstromde71cda2001-03-24 00:43:26 +0000846 /* ignore SIGPIPE */
847 signal(SIGPIPE, SIG_IGN);
Damien Miller95def091999-11-25 00:26:21 +1100848
Damien Miller95def091999-11-25 00:26:21 +1100849 /* Start listening for a socket, unless started from inetd. */
850 if (inetd_flag) {
Ben Lindstrom206941f2001-04-15 14:27:16 +0000851 int s1;
Damien Miller95def091999-11-25 00:26:21 +1100852 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
Ben Lindstrom206941f2001-04-15 14:27:16 +0000853 dup(s1);
Damien Miller95def091999-11-25 00:26:21 +1100854 sock_in = dup(0);
855 sock_out = dup(1);
Damien Miller994cf142000-07-21 10:19:44 +1000856 startup_pipe = -1;
Damien Millereba71ba2000-04-29 23:57:08 +1000857 /*
858 * We intentionally do not close the descriptors 0, 1, and 2
859 * as our code for setting the descriptors won\'t work if
860 * ttyfd happens to be one of those.
861 */
Damien Miller95def091999-11-25 00:26:21 +1100862 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100863 if (options.protocol & SSH_PROTO_1)
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000864 generate_ephemeral_server_key();
Damien Miller95def091999-11-25 00:26:21 +1100865 } else {
Damien Miller34132e52000-01-14 15:45:46 +1100866 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
867 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
868 continue;
869 if (num_listen_socks >= MAX_LISTEN_SOCKS)
870 fatal("Too many listen sockets. "
871 "Enlarge MAX_LISTEN_SOCKS");
872 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
873 ntop, sizeof(ntop), strport, sizeof(strport),
874 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
875 error("getnameinfo failed");
876 continue;
877 }
878 /* Create socket for listening. */
879 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
880 if (listen_sock < 0) {
881 /* kernel may not support ipv6 */
882 verbose("socket: %.100s", strerror(errno));
883 continue;
884 }
885 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
886 error("listen_sock O_NONBLOCK: %s", strerror(errno));
887 close(listen_sock);
888 continue;
889 }
890 /*
891 * Set socket options. We try to make the port
892 * reusable and have it close as fast as possible
893 * without waiting in unnecessary wait states on
894 * close.
895 */
896 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
897 (void *) &on, sizeof(on));
898 linger.l_onoff = 1;
899 linger.l_linger = 5;
900 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
901 (void *) &linger, sizeof(linger));
Damien Miller95def091999-11-25 00:26:21 +1100902
Damien Miller34132e52000-01-14 15:45:46 +1100903 debug("Bind to port %s on %s.", strport, ntop);
Damien Miller95def091999-11-25 00:26:21 +1100904
Damien Miller34132e52000-01-14 15:45:46 +1100905 /* Bind the socket to the desired port. */
Damien Miller0a4e27d2001-02-18 12:36:39 +1100906 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
907 if (!ai->ai_next)
908 error("Bind to port %s on %s failed: %.200s.",
909 strport, ntop, strerror(errno));
Damien Miller34132e52000-01-14 15:45:46 +1100910 close(listen_sock);
911 continue;
912 }
913 listen_socks[num_listen_socks] = listen_sock;
914 num_listen_socks++;
Damien Miller95def091999-11-25 00:26:21 +1100915
Damien Miller34132e52000-01-14 15:45:46 +1100916 /* Start listening on the port. */
917 log("Server listening on %s port %s.", ntop, strport);
918 if (listen(listen_sock, 5) < 0)
919 fatal("listen: %.100s", strerror(errno));
920
Damien Miller95def091999-11-25 00:26:21 +1100921 }
Damien Miller34132e52000-01-14 15:45:46 +1100922 freeaddrinfo(options.listen_addrs);
923
924 if (!num_listen_socks)
925 fatal("Cannot bind any address.");
926
Ben Lindstrom98097862001-06-25 05:10:20 +0000927 if (options.protocol & SSH_PROTO_1)
928 generate_ephemeral_server_key();
929
930 /*
931 * Arrange to restart on SIGHUP. The handler needs
932 * listen_sock.
933 */
934 signal(SIGHUP, sighup_handler);
935
936 signal(SIGTERM, sigterm_handler);
937 signal(SIGQUIT, sigterm_handler);
938
939 /* Arrange SIGCHLD to be caught. */
940 signal(SIGCHLD, main_sigchld_handler);
941
942 /* Write out the pid file after the sigterm handler is setup */
Damien Miller95def091999-11-25 00:26:21 +1100943 if (!debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +1100944 /*
Ben Lindstrom7ad97102000-12-06 01:42:49 +0000945 * Record our pid in /var/run/sshd.pid to make it
946 * easier to kill the correct sshd. We don't want to
947 * do this before the bind above because the bind will
Damien Miller5428f641999-11-25 11:54:57 +1100948 * fail if there already is a daemon, and this will
949 * overwrite any old pid in the file.
950 */
Damien Millerbac2d8a2000-09-05 16:13:06 +1100951 f = fopen(options.pid_file, "wb");
Damien Miller95def091999-11-25 00:26:21 +1100952 if (f) {
Ben Lindstrom46c16222000-12-22 01:43:59 +0000953 fprintf(f, "%u\n", (u_int) getpid());
Damien Miller95def091999-11-25 00:26:21 +1100954 fclose(f);
955 }
956 }
Damien Miller95def091999-11-25 00:26:21 +1100957
Damien Miller34132e52000-01-14 15:45:46 +1100958 /* setup fd set for listen */
Damien Miller37023962000-07-11 17:31:38 +1000959 fdset = NULL;
Damien Miller34132e52000-01-14 15:45:46 +1100960 maxfd = 0;
961 for (i = 0; i < num_listen_socks; i++)
962 if (listen_socks[i] > maxfd)
963 maxfd = listen_socks[i];
Damien Miller37023962000-07-11 17:31:38 +1000964 /* pipes connected to unauthenticated childs */
965 startup_pipes = xmalloc(options.max_startups * sizeof(int));
966 for (i = 0; i < options.max_startups; i++)
967 startup_pipes[i] = -1;
Damien Miller34132e52000-01-14 15:45:46 +1100968
Damien Miller5428f641999-11-25 11:54:57 +1100969 /*
970 * Stay listening for connections until the system crashes or
971 * the daemon is killed with a signal.
972 */
Damien Miller95def091999-11-25 00:26:21 +1100973 for (;;) {
974 if (received_sighup)
975 sighup_restart();
Damien Miller37023962000-07-11 17:31:38 +1000976 if (fdset != NULL)
977 xfree(fdset);
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000978 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
Damien Miller37023962000-07-11 17:31:38 +1000979 fdset = (fd_set *)xmalloc(fdsetsz);
Damien Miller34132e52000-01-14 15:45:46 +1100980 memset(fdset, 0, fdsetsz);
Damien Miller37023962000-07-11 17:31:38 +1000981
Damien Miller34132e52000-01-14 15:45:46 +1100982 for (i = 0; i < num_listen_socks; i++)
983 FD_SET(listen_socks[i], fdset);
Damien Miller37023962000-07-11 17:31:38 +1000984 for (i = 0; i < options.max_startups; i++)
985 if (startup_pipes[i] != -1)
986 FD_SET(startup_pipes[i], fdset);
987
988 /* Wait in select until there is a connection. */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000989 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
990 if (ret < 0 && errno != EINTR)
991 error("select: %.100s", strerror(errno));
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000992 if (received_sigterm) {
993 log("Received signal %d; terminating.",
Ben Lindstromf8f065b2001-12-06 17:52:16 +0000994 (int) received_sigterm);
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000995 close_listen_socks();
996 unlink(options.pid_file);
997 exit(255);
998 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000999 if (key_used && key_do_regen) {
Ben Lindstromca42d5f2001-03-09 18:25:32 +00001000 generate_ephemeral_server_key();
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001001 key_used = 0;
1002 key_do_regen = 0;
Damien Miller34132e52000-01-14 15:45:46 +11001003 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001004 if (ret < 0)
1005 continue;
1006
Damien Miller37023962000-07-11 17:31:38 +10001007 for (i = 0; i < options.max_startups; i++)
1008 if (startup_pipes[i] != -1 &&
1009 FD_ISSET(startup_pipes[i], fdset)) {
1010 /*
1011 * the read end of the pipe is ready
1012 * if the child has closed the pipe
Ben Lindstrom4dccfa52000-12-28 16:40:05 +00001013 * after successful authentication
Damien Miller37023962000-07-11 17:31:38 +10001014 * or if the child has died
1015 */
1016 close(startup_pipes[i]);
1017 startup_pipes[i] = -1;
1018 startups--;
1019 }
Damien Miller34132e52000-01-14 15:45:46 +11001020 for (i = 0; i < num_listen_socks; i++) {
1021 if (!FD_ISSET(listen_socks[i], fdset))
Damien Miller95def091999-11-25 00:26:21 +11001022 continue;
Damien Miller37023962000-07-11 17:31:38 +10001023 fromlen = sizeof(from);
1024 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1025 &fromlen);
1026 if (newsock < 0) {
1027 if (errno != EINTR && errno != EWOULDBLOCK)
1028 error("accept: %.100s", strerror(errno));
1029 continue;
1030 }
1031 if (fcntl(newsock, F_SETFL, 0) < 0) {
1032 error("newsock del O_NONBLOCK: %s", strerror(errno));
Damien Miller72c336d2001-12-21 12:44:28 +11001033 close(newsock);
Damien Miller37023962000-07-11 17:31:38 +10001034 continue;
1035 }
Damien Miller942da032000-08-18 13:59:06 +10001036 if (drop_connection(startups) == 1) {
1037 debug("drop connection #%d", startups);
Damien Miller37023962000-07-11 17:31:38 +10001038 close(newsock);
1039 continue;
1040 }
1041 if (pipe(startup_p) == -1) {
1042 close(newsock);
1043 continue;
1044 }
1045
1046 for (j = 0; j < options.max_startups; j++)
1047 if (startup_pipes[j] == -1) {
1048 startup_pipes[j] = startup_p[0];
1049 if (maxfd < startup_p[0])
1050 maxfd = startup_p[0];
1051 startups++;
1052 break;
1053 }
Kevin Stevesef4eea92001-02-05 12:42:17 +00001054
Damien Miller5428f641999-11-25 11:54:57 +11001055 /*
Damien Miller37023962000-07-11 17:31:38 +10001056 * Got connection. Fork a child to handle it, unless
1057 * we are in debugging mode.
Damien Miller5428f641999-11-25 11:54:57 +11001058 */
Damien Miller37023962000-07-11 17:31:38 +10001059 if (debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +11001060 /*
Damien Miller37023962000-07-11 17:31:38 +10001061 * In debugging mode. Close the listening
1062 * socket, and start processing the
1063 * connection without forking.
Damien Miller5428f641999-11-25 11:54:57 +11001064 */
Damien Miller37023962000-07-11 17:31:38 +10001065 debug("Server will not fork when running in debugging mode.");
Damien Miller34132e52000-01-14 15:45:46 +11001066 close_listen_socks();
Damien Miller95def091999-11-25 00:26:21 +11001067 sock_in = newsock;
1068 sock_out = newsock;
Damien Miller4d97ba22000-07-11 18:15:50 +10001069 startup_pipe = -1;
Damien Miller182ee6e2000-07-12 09:45:27 +10001070 pid = getpid();
Damien Miller95def091999-11-25 00:26:21 +11001071 break;
Damien Miller37023962000-07-11 17:31:38 +10001072 } else {
1073 /*
1074 * Normal production daemon. Fork, and have
1075 * the child process the connection. The
1076 * parent continues listening.
1077 */
1078 if ((pid = fork()) == 0) {
1079 /*
1080 * Child. Close the listening and max_startup
1081 * sockets. Start using the accepted socket.
1082 * Reinitialize logging (since our pid has
1083 * changed). We break out of the loop to handle
1084 * the connection.
1085 */
1086 startup_pipe = startup_p[1];
Ben Lindstromd84df982001-12-06 16:35:40 +00001087 close_startup_pipes();
Damien Miller37023962000-07-11 17:31:38 +10001088 close_listen_socks();
1089 sock_in = newsock;
1090 sock_out = newsock;
Kevin Stevesec84dc12000-12-13 17:45:15 +00001091 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller37023962000-07-11 17:31:38 +10001092 break;
1093 }
Damien Miller95def091999-11-25 00:26:21 +11001094 }
Damien Miller37023962000-07-11 17:31:38 +10001095
1096 /* Parent. Stay in the loop. */
1097 if (pid < 0)
1098 error("fork: %.100s", strerror(errno));
1099 else
1100 debug("Forked child %d.", pid);
1101
1102 close(startup_p[1]);
1103
1104 /* Mark that the key has been used (it was "given" to the child). */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001105 if ((options.protocol & SSH_PROTO_1) &&
1106 key_used == 0) {
1107 /* Schedule server key regeneration alarm. */
1108 signal(SIGALRM, key_regeneration_alarm);
1109 alarm(options.key_regeneration_time);
1110 key_used = 1;
1111 }
Damien Miller37023962000-07-11 17:31:38 +10001112
1113 arc4random_stir();
1114
1115 /* Close the new socket (the child is now taking care of it). */
1116 close(newsock);
Damien Miller95def091999-11-25 00:26:21 +11001117 }
Damien Miller34132e52000-01-14 15:45:46 +11001118 /* child process check (or debug mode) */
1119 if (num_listen_socks < 0)
1120 break;
Damien Miller95def091999-11-25 00:26:21 +11001121 }
1122 }
1123
1124 /* This is the child processing a new connection. */
1125
Damien Miller5428f641999-11-25 11:54:57 +11001126 /*
1127 * Disable the key regeneration alarm. We will not regenerate the
1128 * key since we are no longer in a position to give it to anyone. We
1129 * will not restart on SIGHUP since it no longer makes sense.
1130 */
Damien Miller95def091999-11-25 00:26:21 +11001131 alarm(0);
1132 signal(SIGALRM, SIG_DFL);
1133 signal(SIGHUP, SIG_DFL);
1134 signal(SIGTERM, SIG_DFL);
1135 signal(SIGQUIT, SIG_DFL);
1136 signal(SIGCHLD, SIG_DFL);
Damien Miller4e0f5e12000-08-29 11:05:50 +11001137 signal(SIGINT, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +11001138
Damien Miller5428f641999-11-25 11:54:57 +11001139 /*
1140 * Set socket options for the connection. We want the socket to
1141 * close as fast as possible without waiting for anything. If the
1142 * connection is not a socket, these will do nothing.
1143 */
1144 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
Damien Miller95def091999-11-25 00:26:21 +11001145 linger.l_onoff = 1;
1146 linger.l_linger = 5;
1147 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1148
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001149 /* Set keepalives if requested. */
1150 if (options.keepalives &&
1151 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1152 sizeof(on)) < 0)
1153 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1154
Damien Miller5428f641999-11-25 11:54:57 +11001155 /*
1156 * Register our connection. This turns encryption off because we do
1157 * not have a key.
1158 */
Damien Miller95def091999-11-25 00:26:21 +11001159 packet_set_connection(sock_in, sock_out);
1160
1161 remote_port = get_remote_port();
1162 remote_ip = get_remote_ipaddr();
1163
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001164#ifdef LIBWRAP
Damien Miller6a4a4b92001-11-12 11:07:11 +11001165 /* Check whether logins are denied from this host. */
Damien Miller95def091999-11-25 00:26:21 +11001166 {
1167 struct request_info req;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001168
Ben Lindstromce89dac2001-09-12 16:58:04 +00001169 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
Damien Miller95def091999-11-25 00:26:21 +11001170 fromhost(&req);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001171
Damien Miller95def091999-11-25 00:26:21 +11001172 if (!hosts_access(&req)) {
Damien Miller6a4a4b92001-11-12 11:07:11 +11001173 debug("Connection refused by tcp wrapper");
Ben Lindstrom7de696e2001-03-29 00:45:12 +00001174 refuse(&req);
Damien Miller6a4a4b92001-11-12 11:07:11 +11001175 /* NOTREACHED */
1176 fatal("libwrap refuse returns");
Damien Miller95def091999-11-25 00:26:21 +11001177 }
Damien Miller95def091999-11-25 00:26:21 +11001178 }
Damien Miller34132e52000-01-14 15:45:46 +11001179#endif /* LIBWRAP */
Damien Miller6a4a4b92001-11-12 11:07:11 +11001180
Damien Miller95def091999-11-25 00:26:21 +11001181 /* Log the connection. */
1182 verbose("Connection from %.500s port %d", remote_ip, remote_port);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001183
Damien Miller5428f641999-11-25 11:54:57 +11001184 /*
1185 * We don\'t want to listen forever unless the other side
1186 * successfully authenticates itself. So we set up an alarm which is
1187 * cleared after successful authentication. A limit of zero
1188 * indicates no limit. Note that we don\'t set the alarm in debugging
1189 * mode; it is just annoying to have the server exit just when you
1190 * are about to discover the bug.
1191 */
Damien Miller95def091999-11-25 00:26:21 +11001192 signal(SIGALRM, grace_alarm_handler);
1193 if (!debug_flag)
1194 alarm(options.login_grace_time);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001195
Damien Millerb38eff82000-04-01 11:09:21 +10001196 sshd_exchange_identification(sock_in, sock_out);
Damien Miller5428f641999-11-25 11:54:57 +11001197 /*
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001198 * Check that the connection comes from a privileged port.
1199 * Rhosts-Authentication only makes sense from priviledged
Damien Miller5428f641999-11-25 11:54:57 +11001200 * programs. Of course, if the intruder has root access on his local
1201 * machine, he can connect from any port. So do not use these
1202 * authentication methods from machines that you do not trust.
1203 */
Damien Miller95def091999-11-25 00:26:21 +11001204 if (remote_port >= IPPORT_RESERVED ||
1205 remote_port < IPPORT_RESERVED / 2) {
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001206 debug("Rhosts Authentication disabled, "
Damien Miller00b61642001-11-12 10:51:23 +11001207 "originating port %d not trusted.", remote_port);
Damien Miller95def091999-11-25 00:26:21 +11001208 options.rhosts_authentication = 0;
Damien Miller95def091999-11-25 00:26:21 +11001209 }
Ben Lindstromec95ed92001-07-04 04:21:14 +00001210#if defined(KRB4) && !defined(KRB5)
Damien Miller34132e52000-01-14 15:45:46 +11001211 if (!packet_connection_is_ipv4() &&
1212 options.kerberos_authentication) {
1213 debug("Kerberos Authentication disabled, only available for IPv4.");
1214 options.kerberos_authentication = 0;
1215 }
Ben Lindstromec95ed92001-07-04 04:21:14 +00001216#endif /* KRB4 && !KRB5 */
Ben Lindstromf79aeff2001-02-10 21:27:11 +00001217#ifdef AFS
1218 /* If machine has AFS, set process authentication group. */
1219 if (k_hasafs()) {
1220 k_setpag();
1221 k_unlog();
1222 }
1223#endif /* AFS */
Damien Miller34132e52000-01-14 15:45:46 +11001224
Damien Miller95def091999-11-25 00:26:21 +11001225 packet_set_nonblocking();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001226
Damien Miller396691a2000-01-20 22:44:08 +11001227 /* perform the key exchange */
Damien Miller396691a2000-01-20 22:44:08 +11001228 /* authenticate user and start session */
Damien Millerefb4afe2000-04-12 18:45:05 +10001229 if (compat20) {
1230 do_ssh2_kex();
1231 do_authentication2();
1232 } else {
1233 do_ssh1_kex();
1234 do_authentication();
1235 }
Damien Miller95def091999-11-25 00:26:21 +11001236 /* The connection has been terminated. */
1237 verbose("Closing connection to %.100s", remote_ip);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001238
Damien Millerbeb4ba51999-12-28 15:09:35 +11001239#ifdef USE_PAM
Damien Millere72b7af1999-12-30 15:08:44 +11001240 finish_pam();
Damien Millerbeb4ba51999-12-28 15:09:35 +11001241#endif /* USE_PAM */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001242
Damien Miller95def091999-11-25 00:26:21 +11001243 packet_close();
1244 exit(0);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001245}
1246
Damien Miller95def091999-11-25 00:26:21 +11001247/*
Damien Miller396691a2000-01-20 22:44:08 +11001248 * SSH1 key exchange
Damien Miller95def091999-11-25 00:26:21 +11001249 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001250static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001251do_ssh1_kex(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001252{
Damien Miller95def091999-11-25 00:26:21 +11001253 int i, len;
Damien Miller396691a2000-01-20 22:44:08 +11001254 int plen, slen;
Damien Miller7650bc62001-01-30 09:27:26 +11001255 int rsafail = 0;
Damien Miller95def091999-11-25 00:26:21 +11001256 BIGNUM *session_key_int;
Ben Lindstrom46c16222000-12-22 01:43:59 +00001257 u_char session_key[SSH_SESSION_KEY_LENGTH];
1258 u_char cookie[8];
1259 u_int cipher_type, auth_mask, protocol_flags;
Damien Miller95def091999-11-25 00:26:21 +11001260 u_int32_t rand = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001261
Damien Miller5428f641999-11-25 11:54:57 +11001262 /*
1263 * Generate check bytes that the client must send back in the user
1264 * packet in order for it to be accepted; this is used to defy ip
1265 * spoofing attacks. Note that this only works against somebody
1266 * doing IP spoofing from a remote machine; any machine on the local
1267 * network can still see outgoing packets and catch the random
1268 * cookie. This only affects rhosts authentication, and this is one
1269 * of the reasons why it is inherently insecure.
1270 */
Damien Miller95def091999-11-25 00:26:21 +11001271 for (i = 0; i < 8; i++) {
1272 if (i % 4 == 0)
1273 rand = arc4random();
Damien Miller396691a2000-01-20 22:44:08 +11001274 cookie[i] = rand & 0xff;
Damien Miller95def091999-11-25 00:26:21 +11001275 rand >>= 8;
1276 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001277
Damien Miller5428f641999-11-25 11:54:57 +11001278 /*
1279 * Send our public key. We include in the packet 64 bits of random
1280 * data that must be matched in the reply in order to prevent IP
1281 * spoofing.
1282 */
Damien Miller95def091999-11-25 00:26:21 +11001283 packet_start(SSH_SMSG_PUBLIC_KEY);
1284 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001285 packet_put_char(cookie[i]);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001286
Damien Miller95def091999-11-25 00:26:21 +11001287 /* Store our public server RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001288 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1289 packet_put_bignum(sensitive_data.server_key->rsa->e);
1290 packet_put_bignum(sensitive_data.server_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001291
Damien Miller95def091999-11-25 00:26:21 +11001292 /* Store our public host RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001293 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1294 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1295 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001296
Damien Miller95def091999-11-25 00:26:21 +11001297 /* Put protocol flags. */
1298 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001299
Damien Miller95def091999-11-25 00:26:21 +11001300 /* Declare which ciphers we support. */
Damien Miller874d77b2000-10-14 16:23:11 +11001301 packet_put_int(cipher_mask_ssh1(0));
Damien Miller95def091999-11-25 00:26:21 +11001302
1303 /* Declare supported authentication types. */
1304 auth_mask = 0;
1305 if (options.rhosts_authentication)
1306 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1307 if (options.rhosts_rsa_authentication)
1308 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1309 if (options.rsa_authentication)
1310 auth_mask |= 1 << SSH_AUTH_RSA;
Ben Lindstromec95ed92001-07-04 04:21:14 +00001311#if defined(KRB4) || defined(KRB5)
Damien Miller95def091999-11-25 00:26:21 +11001312 if (options.kerberos_authentication)
1313 auth_mask |= 1 << SSH_AUTH_KERBEROS;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001314#endif
Ben Lindstromec95ed92001-07-04 04:21:14 +00001315#if defined(AFS) || defined(KRB5)
Damien Miller95def091999-11-25 00:26:21 +11001316 if (options.kerberos_tgt_passing)
1317 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
Ben Lindstromec95ed92001-07-04 04:21:14 +00001318#endif
1319#ifdef AFS
Damien Miller95def091999-11-25 00:26:21 +11001320 if (options.afs_token_passing)
1321 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001322#endif
Ben Lindstrom551ea372001-06-05 18:56:16 +00001323 if (options.challenge_response_authentication == 1)
Damien Miller95def091999-11-25 00:26:21 +11001324 auth_mask |= 1 << SSH_AUTH_TIS;
Damien Miller95def091999-11-25 00:26:21 +11001325 if (options.password_authentication)
1326 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1327 packet_put_int(auth_mask);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001328
Damien Miller95def091999-11-25 00:26:21 +11001329 /* Send the packet and wait for it to be sent. */
1330 packet_send();
1331 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001332
Damien Miller0bc1bd82000-11-13 22:57:25 +11001333 debug("Sent %d bit server key and %d bit host key.",
1334 BN_num_bits(sensitive_data.server_key->rsa->n),
1335 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001336
Damien Miller95def091999-11-25 00:26:21 +11001337 /* Read clients reply (cipher type and session key). */
1338 packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001339
Damien Miller50945fa1999-12-09 10:31:37 +11001340 /* Get cipher type and check whether we accept this. */
Damien Miller95def091999-11-25 00:26:21 +11001341 cipher_type = packet_get_char();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001342
Damien Miller874d77b2000-10-14 16:23:11 +11001343 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
Damien Miller50945fa1999-12-09 10:31:37 +11001344 packet_disconnect("Warning: client selects unsupported cipher.");
1345
Damien Miller95def091999-11-25 00:26:21 +11001346 /* Get check bytes from the packet. These must match those we
1347 sent earlier with the public key packet. */
1348 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001349 if (cookie[i] != packet_get_char())
Damien Miller95def091999-11-25 00:26:21 +11001350 packet_disconnect("IP Spoofing check bytes do not match.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001351
Damien Miller95def091999-11-25 00:26:21 +11001352 debug("Encryption type: %.200s", cipher_name(cipher_type));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001353
Damien Miller95def091999-11-25 00:26:21 +11001354 /* Get the encrypted integer. */
1355 session_key_int = BN_new();
1356 packet_get_bignum(session_key_int, &slen);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001357
Damien Miller95def091999-11-25 00:26:21 +11001358 protocol_flags = packet_get_int();
1359 packet_set_protocol_flags(protocol_flags);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001360
Damien Miller95def091999-11-25 00:26:21 +11001361 packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001362
Damien Miller5428f641999-11-25 11:54:57 +11001363 /*
1364 * Decrypt it using our private server key and private host key (key
1365 * with larger modulus first).
1366 */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001367 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
Damien Miller7650bc62001-01-30 09:27:26 +11001368 /* Server key has bigger modulus. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001369 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1370 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1371 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1372 get_remote_ipaddr(),
1373 BN_num_bits(sensitive_data.server_key->rsa->n),
1374 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1375 SSH_KEY_BITS_RESERVED);
Damien Miller95def091999-11-25 00:26:21 +11001376 }
Damien Miller7650bc62001-01-30 09:27:26 +11001377 if (rsa_private_decrypt(session_key_int, session_key_int,
1378 sensitive_data.server_key->rsa) <= 0)
1379 rsafail++;
1380 if (rsa_private_decrypt(session_key_int, session_key_int,
1381 sensitive_data.ssh1_host_key->rsa) <= 0)
1382 rsafail++;
Damien Miller95def091999-11-25 00:26:21 +11001383 } else {
1384 /* Host key has bigger modulus (or they are equal). */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001385 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1386 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1387 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1388 get_remote_ipaddr(),
1389 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1390 BN_num_bits(sensitive_data.server_key->rsa->n),
1391 SSH_KEY_BITS_RESERVED);
Damien Miller95def091999-11-25 00:26:21 +11001392 }
Damien Miller7650bc62001-01-30 09:27:26 +11001393 if (rsa_private_decrypt(session_key_int, session_key_int,
1394 sensitive_data.ssh1_host_key->rsa) < 0)
1395 rsafail++;
1396 if (rsa_private_decrypt(session_key_int, session_key_int,
1397 sensitive_data.server_key->rsa) < 0)
1398 rsafail++;
Damien Miller95def091999-11-25 00:26:21 +11001399 }
Damien Miller5428f641999-11-25 11:54:57 +11001400 /*
1401 * Extract session key from the decrypted integer. The key is in the
1402 * least significant 256 bits of the integer; the first byte of the
1403 * key is in the highest bits.
1404 */
Damien Miller7650bc62001-01-30 09:27:26 +11001405 if (!rsafail) {
1406 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1407 len = BN_num_bytes(session_key_int);
1408 if (len < 0 || len > sizeof(session_key)) {
1409 error("do_connection: bad session key len from %s: "
Ben Lindstrom31ca54a2001-02-09 02:11:24 +00001410 "session_key_int %d > sizeof(session_key) %lu",
1411 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
Damien Miller7650bc62001-01-30 09:27:26 +11001412 rsafail++;
1413 } else {
1414 memset(session_key, 0, sizeof(session_key));
1415 BN_bn2bin(session_key_int,
1416 session_key + sizeof(session_key) - len);
Ben Lindstromeb648a72001-03-05 06:00:29 +00001417
1418 compute_session_id(session_id, cookie,
1419 sensitive_data.ssh1_host_key->rsa->n,
1420 sensitive_data.server_key->rsa->n);
1421 /*
1422 * Xor the first 16 bytes of the session key with the
1423 * session id.
1424 */
1425 for (i = 0; i < 16; i++)
1426 session_key[i] ^= session_id[i];
Damien Miller7650bc62001-01-30 09:27:26 +11001427 }
1428 }
1429 if (rsafail) {
Ben Lindstromeb648a72001-03-05 06:00:29 +00001430 int bytes = BN_num_bytes(session_key_int);
1431 char *buf = xmalloc(bytes);
1432 MD5_CTX md;
1433
Damien Miller7650bc62001-01-30 09:27:26 +11001434 log("do_connection: generating a fake encryption key");
Ben Lindstromeb648a72001-03-05 06:00:29 +00001435 BN_bn2bin(session_key_int, buf);
1436 MD5_Init(&md);
1437 MD5_Update(&md, buf, bytes);
1438 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1439 MD5_Final(session_key, &md);
1440 MD5_Init(&md);
1441 MD5_Update(&md, session_key, 16);
1442 MD5_Update(&md, buf, bytes);
1443 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1444 MD5_Final(session_key + 16, &md);
1445 memset(buf, 0, bytes);
1446 xfree(buf);
Ben Lindstrom941ac822001-03-05 06:25:23 +00001447 for (i = 0; i < 16; i++)
1448 session_id[i] = session_key[i] ^ session_key[i + 16];
Damien Miller7650bc62001-01-30 09:27:26 +11001449 }
Ben Lindstromeb648a72001-03-05 06:00:29 +00001450 /* Destroy the private and public keys. They will no longer be needed. */
1451 destroy_sensitive_data();
1452
Damien Miller396691a2000-01-20 22:44:08 +11001453 /* Destroy the decrypted integer. It is no longer needed. */
1454 BN_clear_free(session_key_int);
1455
Damien Miller95def091999-11-25 00:26:21 +11001456 /* Set the session key. From this on all communications will be encrypted. */
1457 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001458
Damien Miller95def091999-11-25 00:26:21 +11001459 /* Destroy our copy of the session key. It is no longer needed. */
1460 memset(session_key, 0, sizeof(session_key));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001461
Damien Miller95def091999-11-25 00:26:21 +11001462 debug("Received session key; encryption turned on.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001463
Damien Miller95def091999-11-25 00:26:21 +11001464 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1465 packet_start(SSH_SMSG_SUCCESS);
1466 packet_send();
1467 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001468}
Damien Millerefb4afe2000-04-12 18:45:05 +10001469
1470/*
1471 * SSH2 key exchange: diffie-hellman-group1-sha1
1472 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001473static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001474do_ssh2_kex(void)
Damien Millerefb4afe2000-04-12 18:45:05 +10001475{
Damien Millerefb4afe2000-04-12 18:45:05 +10001476 Kex *kex;
Damien Millerefb4afe2000-04-12 18:45:05 +10001477
Damien Miller78928792000-04-12 20:17:38 +10001478 if (options.ciphers != NULL) {
Damien Miller4af51302000-04-16 11:18:38 +10001479 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
Damien Miller78928792000-04-12 20:17:38 +10001480 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1481 }
Damien Millera0ff4662001-03-30 10:49:35 +10001482 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1483 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1484 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1485 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1486
Ben Lindstrom06b33aa2001-02-15 03:01:59 +00001487 if (options.macs != NULL) {
1488 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1489 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1490 }
Damien Miller0bc1bd82000-11-13 22:57:25 +11001491 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1492
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001493 /* start key exchange */
Ben Lindstrom238abf62001-04-04 17:52:53 +00001494 kex = kex_setup(myproposal);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001495 kex->server = 1;
1496 kex->client_version_string=client_version_string;
1497 kex->server_version_string=server_version_string;
1498 kex->load_host_key=&get_hostkey_by_type;
Damien Millerefb4afe2000-04-12 18:45:05 +10001499
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001500 xxx_kex = kex;
1501
Ben Lindstrombe2cc432001-04-04 23:46:07 +00001502 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
Damien Miller874d77b2000-10-14 16:23:11 +11001503
Ben Lindstrom2d90e002001-04-04 02:00:54 +00001504 session_id2 = kex->session_id;
1505 session_id2_len = kex->session_id_len;
1506
Damien Miller874d77b2000-10-14 16:23:11 +11001507#ifdef DEBUG_KEXDH
1508 /* send 1st encrypted/maced/compressed message */
1509 packet_start(SSH2_MSG_IGNORE);
1510 packet_put_cstring("markus");
1511 packet_send();
1512 packet_write_wait();
1513#endif
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001514 debug("KEX done");
Damien Millerefb4afe2000-04-12 18:45:05 +10001515}