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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 Miller6a47f302002-02-13 13:55:06 +110043RCSID("$OpenBSD: sshd.c,v 1.226 2002/02/11 16:19:39 markus 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>
Damien Miller6a47f302002-02-13 13:55:06 +110047#include <openssl/md5.h>
Ben Lindstrom226cfa02001-01-22 05:34:40 +000048
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{
Damien Miller0e3b8722002-01-22 23:26:38 +1100483 Buffer b;
484 char *p;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100485 int i;
Damien Miller0e3b8722002-01-22 23:26:38 +1100486
487 buffer_init(&b);
Damien Miller9f0f5c62001-12-21 14:45:46 +1100488 for (i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100489 Key *key = sensitive_data.host_keys[i];
490 if (key == NULL)
491 continue;
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000492 switch (key->type) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100493 case KEY_RSA:
494 case KEY_DSA:
Damien Miller0e3b8722002-01-22 23:26:38 +1100495 if (buffer_len(&b) > 0)
496 buffer_append(&b, ",", 1);
497 p = key_ssh_name(key);
498 buffer_append(&b, p, strlen(p));
Damien Miller0bc1bd82000-11-13 22:57:25 +1100499 break;
500 }
501 }
Damien Miller0e3b8722002-01-22 23:26:38 +1100502 buffer_append(&b, "\0", 1);
503 p = xstrdup(buffer_ptr(&b));
504 buffer_free(&b);
505 debug("list_hostkey_types: %s", p);
506 return p;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100507}
508
Ben Lindstrombba81212001-06-25 05:01:22 +0000509static Key *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100510get_hostkey_by_type(int type)
511{
512 int i;
Damien Miller9f0f5c62001-12-21 14:45:46 +1100513 for (i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100514 Key *key = sensitive_data.host_keys[i];
515 if (key != NULL && key->type == type)
516 return key;
517 }
518 return NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000519}
520
Damien Miller942da032000-08-18 13:59:06 +1000521/*
522 * returns 1 if connection should be dropped, 0 otherwise.
523 * dropping starts at connection #max_startups_begin with a probability
524 * of (max_startups_rate/100). the probability increases linearly until
525 * all connections are dropped for startups > max_startups
526 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000527static int
Damien Miller942da032000-08-18 13:59:06 +1000528drop_connection(int startups)
529{
530 double p, r;
531
532 if (startups < options.max_startups_begin)
533 return 0;
534 if (startups >= options.max_startups)
535 return 1;
536 if (options.max_startups_rate == 100)
537 return 1;
538
539 p = 100 - options.max_startups_rate;
540 p *= startups - options.max_startups_begin;
541 p /= (double) (options.max_startups - options.max_startups_begin);
542 p += options.max_startups_rate;
543 p /= 100.0;
544 r = arc4random() / (double) UINT_MAX;
545
546 debug("drop_connection: p %g, r %g", p, r);
547 return (r < p) ? 1 : 0;
548}
549
Ben Lindstromade03f62001-12-06 18:22:17 +0000550static void
551usage(void)
552{
553 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
554 fprintf(stderr, "Usage: %s [options]\n", __progname);
555 fprintf(stderr, "Options:\n");
556 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
557 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
558 fprintf(stderr, " -i Started from inetd\n");
559 fprintf(stderr, " -D Do not fork into daemon mode\n");
560 fprintf(stderr, " -t Only test configuration file and keys\n");
561 fprintf(stderr, " -q Quiet (no logging)\n");
562 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
563 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
564 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
565 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
566 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
567 _PATH_HOST_KEY_FILE);
568 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
569 fprintf(stderr, " -4 Use IPv4 only\n");
570 fprintf(stderr, " -6 Use IPv6 only\n");
571 fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n");
572 exit(1);
573}
574
Damien Miller95def091999-11-25 00:26:21 +1100575/*
576 * Main program for the daemon.
577 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000578int
579main(int ac, char **av)
580{
Damien Miller95def091999-11-25 00:26:21 +1100581 extern char *optarg;
582 extern int optind;
Damien Miller37023962000-07-11 17:31:38 +1000583 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
Damien Miller166fca82000-04-20 07:42:21 +1000584 pid_t pid;
Damien Miller34132e52000-01-14 15:45:46 +1100585 socklen_t fromlen;
Damien Miller34132e52000-01-14 15:45:46 +1100586 fd_set *fdset;
587 struct sockaddr_storage from;
Damien Miller95def091999-11-25 00:26:21 +1100588 const char *remote_ip;
589 int remote_port;
Damien Miller95def091999-11-25 00:26:21 +1100590 FILE *f;
591 struct linger linger;
Damien Miller34132e52000-01-14 15:45:46 +1100592 struct addrinfo *ai;
593 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
594 int listen_sock, maxfd;
Damien Miller37023962000-07-11 17:31:38 +1000595 int startup_p[2];
596 int startups = 0;
Ben Lindstromd0fca422001-03-26 13:44:06 +0000597 Key *key;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000598 int ret, key_used = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000599
Ben Lindstrom49a79c02000-11-17 03:47:20 +0000600 __progname = get_progname(av[0]);
Damien Millerf9b625c2000-07-09 22:42:32 +1000601 init_rng();
602
Kevin Stevesec84dc12000-12-13 17:45:15 +0000603 /* Save argv. */
Damien Millerb8c656e2000-06-28 15:22:41 +1000604 saved_argc = ac;
Damien Miller95def091999-11-25 00:26:21 +1100605 saved_argv = av;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000606
Damien Miller95def091999-11-25 00:26:21 +1100607 /* Initialize configuration options to their default values. */
608 initialize_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000609
Damien Miller95def091999-11-25 00:26:21 +1100610 /* Parse command-line arguments. */
Ben Lindstromade03f62001-12-06 18:22:17 +0000611 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) {
Damien Miller95def091999-11-25 00:26:21 +1100612 switch (opt) {
Damien Miller34132e52000-01-14 15:45:46 +1100613 case '4':
614 IPv4or6 = AF_INET;
615 break;
616 case '6':
617 IPv4or6 = AF_INET6;
618 break;
Damien Miller95def091999-11-25 00:26:21 +1100619 case 'f':
620 config_file_name = optarg;
621 break;
622 case 'd':
Damien Millere4340be2000-09-16 13:29:08 +1100623 if (0 == debug_flag) {
624 debug_flag = 1;
625 options.log_level = SYSLOG_LEVEL_DEBUG1;
626 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
627 options.log_level++;
628 } else {
629 fprintf(stderr, "Too high debugging level.\n");
630 exit(1);
631 }
Damien Miller95def091999-11-25 00:26:21 +1100632 break;
Ben Lindstromc72745a2000-12-02 19:03:54 +0000633 case 'D':
634 no_daemon_flag = 1;
635 break;
Ben Lindstrom9fce9f02001-04-11 23:10:09 +0000636 case 'e':
637 log_stderr = 1;
638 break;
Damien Miller95def091999-11-25 00:26:21 +1100639 case 'i':
640 inetd_flag = 1;
641 break;
642 case 'Q':
Ben Lindstromd5390202001-01-29 08:07:43 +0000643 /* ignored */
Damien Miller95def091999-11-25 00:26:21 +1100644 break;
645 case 'q':
646 options.log_level = SYSLOG_LEVEL_QUIET;
647 break;
648 case 'b':
649 options.server_key_bits = atoi(optarg);
650 break;
651 case 'p':
Damien Miller34132e52000-01-14 15:45:46 +1100652 options.ports_from_cmdline = 1;
Damien Millere4340be2000-09-16 13:29:08 +1100653 if (options.num_ports >= MAX_PORTS) {
654 fprintf(stderr, "too many ports.\n");
655 exit(1);
656 }
Ben Lindstrom19066a12001-04-12 23:39:26 +0000657 options.ports[options.num_ports++] = a2port(optarg);
658 if (options.ports[options.num_ports-1] == 0) {
659 fprintf(stderr, "Bad port number.\n");
660 exit(1);
661 }
Damien Miller95def091999-11-25 00:26:21 +1100662 break;
663 case 'g':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000664 if ((options.login_grace_time = convtime(optarg)) == -1) {
665 fprintf(stderr, "Invalid login grace time.\n");
666 exit(1);
667 }
Damien Miller95def091999-11-25 00:26:21 +1100668 break;
669 case 'k':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000670 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
671 fprintf(stderr, "Invalid key regeneration interval.\n");
672 exit(1);
673 }
Damien Miller95def091999-11-25 00:26:21 +1100674 break;
675 case 'h':
Damien Miller0bc1bd82000-11-13 22:57:25 +1100676 if (options.num_host_key_files >= MAX_HOSTKEYS) {
677 fprintf(stderr, "too many host keys.\n");
678 exit(1);
679 }
680 options.host_key_files[options.num_host_key_files++] = optarg;
Damien Miller95def091999-11-25 00:26:21 +1100681 break;
682 case 'V':
683 client_version_string = optarg;
684 /* only makes sense with inetd_flag, i.e. no listen() */
685 inetd_flag = 1;
686 break;
Ben Lindstrom794325a2001-08-06 21:09:07 +0000687 case 't':
688 test_flag = 1;
689 break;
Damien Miller942da032000-08-18 13:59:06 +1000690 case 'u':
691 utmp_len = atoi(optarg);
692 break;
Ben Lindstromade03f62001-12-06 18:22:17 +0000693 case 'o':
Damien Miller9f0f5c62001-12-21 14:45:46 +1100694 if (process_server_config_line(&options, optarg,
Ben Lindstromade03f62001-12-06 18:22:17 +0000695 "command-line", 0) != 0)
Damien Miller9f0f5c62001-12-21 14:45:46 +1100696 exit(1);
Ben Lindstromade03f62001-12-06 18:22:17 +0000697 break;
Damien Miller95def091999-11-25 00:26:21 +1100698 case '?':
699 default:
Ben Lindstromade03f62001-12-06 18:22:17 +0000700 usage();
701 break;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000702 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000703 }
Ben Lindstrom425fb022001-03-29 00:31:20 +0000704 SSLeay_add_all_algorithms();
Ben Lindstrom908afed2001-10-03 17:34:59 +0000705 channel_set_af(IPv4or6);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000706
Damien Miller34132e52000-01-14 15:45:46 +1100707 /*
708 * Force logging to stderr until we have loaded the private host
709 * key (unless started from inetd)
710 */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000711 log_init(__progname,
Damien Miller5aa5d782002-02-08 22:01:54 +1100712 options.log_level == SYSLOG_LEVEL_NOT_SET ?
713 SYSLOG_LEVEL_INFO : options.log_level,
714 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
715 SYSLOG_FACILITY_AUTH : options.log_facility,
Ben Lindstromd5390202001-01-29 08:07:43 +0000716 !inetd_flag);
Damien Miller34132e52000-01-14 15:45:46 +1100717
Ben Lindstrom6db66ff2001-08-06 23:29:16 +0000718#ifdef _CRAY
719 /* Cray can define user privs drop all prives now!
720 * Not needed on PRIV_SU systems!
721 */
722 drop_cray_privs();
723#endif
724
Damien Miller60bc5172001-03-19 09:38:15 +1100725 seed_rng();
726
Damien Miller95def091999-11-25 00:26:21 +1100727 /* Read server configuration options from the configuration file. */
728 read_server_config(&options, config_file_name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000729
Damien Miller95def091999-11-25 00:26:21 +1100730 /* Fill in default values for those options not explicitly set. */
731 fill_default_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000732
Damien Miller95def091999-11-25 00:26:21 +1100733 /* Check that there are no remaining arguments. */
734 if (optind < ac) {
735 fprintf(stderr, "Extra argument %s.\n", av[optind]);
736 exit(1);
737 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000738
Damien Miller95def091999-11-25 00:26:21 +1100739 debug("sshd version %.100s", SSH_VERSION);
Damien Miller2ccf6611999-11-15 15:25:10 +1100740
Damien Miller0bc1bd82000-11-13 22:57:25 +1100741 /* load private host keys */
742 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
Damien Miller9f0f5c62001-12-21 14:45:46 +1100743 for (i = 0; i < options.num_host_key_files; i++)
Ben Lindstrom46c16222000-12-22 01:43:59 +0000744 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100745 sensitive_data.server_key = NULL;
746 sensitive_data.ssh1_host_key = NULL;
747 sensitive_data.have_ssh1_key = 0;
748 sensitive_data.have_ssh2_key = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000749
Damien Miller9f0f5c62001-12-21 14:45:46 +1100750 for (i = 0; i < options.num_host_key_files; i++) {
Ben Lindstromd0fca422001-03-26 13:44:06 +0000751 key = key_load_private(options.host_key_files[i], "", NULL);
752 sensitive_data.host_keys[i] = key;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100753 if (key == NULL) {
Ben Lindstrom15f33862001-04-16 02:00:02 +0000754 error("Could not load host key: %s",
755 options.host_key_files[i]);
Ben Lindstromd0fca422001-03-26 13:44:06 +0000756 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100757 continue;
758 }
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000759 switch (key->type) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100760 case KEY_RSA1:
761 sensitive_data.ssh1_host_key = key;
762 sensitive_data.have_ssh1_key = 1;
763 break;
764 case KEY_RSA:
765 case KEY_DSA:
766 sensitive_data.have_ssh2_key = 1;
767 break;
768 }
Ben Lindstromd0fca422001-03-26 13:44:06 +0000769 debug("private host key: #%d type %d %s", i, key->type,
770 key_type(key));
Damien Miller0bc1bd82000-11-13 22:57:25 +1100771 }
772 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
773 log("Disabling protocol version 1. Could not load host key");
Damien Millereba71ba2000-04-29 23:57:08 +1000774 options.protocol &= ~SSH_PROTO_1;
775 }
Damien Miller0bc1bd82000-11-13 22:57:25 +1100776 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
777 log("Disabling protocol version 2. Could not load host key");
778 options.protocol &= ~SSH_PROTO_2;
Damien Millereba71ba2000-04-29 23:57:08 +1000779 }
Kevin Stevesadf74cd2001-02-05 14:22:50 +0000780 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
Ben Lindstrom6df8ef42001-03-05 07:47:23 +0000781 log("sshd: no hostkeys available -- exiting.");
Damien Miller95def091999-11-25 00:26:21 +1100782 exit(1);
783 }
Damien Miller95def091999-11-25 00:26:21 +1100784
Damien Millereba71ba2000-04-29 23:57:08 +1000785 /* Check certain values for sanity. */
786 if (options.protocol & SSH_PROTO_1) {
787 if (options.server_key_bits < 512 ||
788 options.server_key_bits > 32768) {
789 fprintf(stderr, "Bad server key size.\n");
790 exit(1);
791 }
792 /*
793 * Check that server and host key lengths differ sufficiently. This
794 * is necessary to make double encryption work with rsaref. Oh, I
795 * hate software patents. I dont know if this can go? Niels
796 */
797 if (options.server_key_bits >
Damien Miller0bc1bd82000-11-13 22:57:25 +1100798 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
Damien Millereba71ba2000-04-29 23:57:08 +1000799 options.server_key_bits <
Damien Miller0bc1bd82000-11-13 22:57:25 +1100800 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
Damien Millereba71ba2000-04-29 23:57:08 +1000801 options.server_key_bits =
Damien Miller0bc1bd82000-11-13 22:57:25 +1100802 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
Damien Millereba71ba2000-04-29 23:57:08 +1000803 debug("Forcing server key to %d bits to make it differ from host key.",
804 options.server_key_bits);
805 }
806 }
807
Ben Lindstrom794325a2001-08-06 21:09:07 +0000808 /* Configuration looks good, so exit if in test mode. */
809 if (test_flag)
810 exit(0);
811
Damien Miller78315eb2000-09-29 23:01:36 +1100812#ifdef HAVE_SCO_PROTECTED_PW
813 (void) set_auth_parameters(ac, av);
814#endif
815
Damien Millereba71ba2000-04-29 23:57:08 +1000816 /* Initialize the log (it is reinitialized below in case we forked). */
Damien Miller95def091999-11-25 00:26:21 +1100817 if (debug_flag && !inetd_flag)
818 log_stderr = 1;
Kevin Stevesec84dc12000-12-13 17:45:15 +0000819 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +1100820
Damien Millereba71ba2000-04-29 23:57:08 +1000821 /*
822 * If not in debugging mode, and not started from inetd, disconnect
823 * from the controlling terminal, and fork. The original process
824 * exits.
825 */
Ben Lindstromc72745a2000-12-02 19:03:54 +0000826 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
Damien Miller95def091999-11-25 00:26:21 +1100827#ifdef TIOCNOTTY
828 int fd;
829#endif /* TIOCNOTTY */
830 if (daemon(0, 0) < 0)
831 fatal("daemon() failed: %.200s", strerror(errno));
832
833 /* Disconnect from the controlling tty. */
834#ifdef TIOCNOTTY
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000835 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
Damien Miller95def091999-11-25 00:26:21 +1100836 if (fd >= 0) {
837 (void) ioctl(fd, TIOCNOTTY, NULL);
838 close(fd);
839 }
840#endif /* TIOCNOTTY */
841 }
842 /* Reinitialize the log (because of the fork above). */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000843 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +1100844
Damien Miller95def091999-11-25 00:26:21 +1100845 /* Initialize the random number generator. */
846 arc4random_stir();
847
848 /* Chdir to the root directory so that the current disk can be
849 unmounted if desired. */
850 chdir("/");
Damien Miller9f0f5c62001-12-21 14:45:46 +1100851
Ben Lindstromde71cda2001-03-24 00:43:26 +0000852 /* ignore SIGPIPE */
853 signal(SIGPIPE, SIG_IGN);
Damien Miller95def091999-11-25 00:26:21 +1100854
Damien Miller95def091999-11-25 00:26:21 +1100855 /* Start listening for a socket, unless started from inetd. */
856 if (inetd_flag) {
Ben Lindstrom206941f2001-04-15 14:27:16 +0000857 int s1;
Damien Miller95def091999-11-25 00:26:21 +1100858 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
Ben Lindstrom206941f2001-04-15 14:27:16 +0000859 dup(s1);
Damien Miller95def091999-11-25 00:26:21 +1100860 sock_in = dup(0);
861 sock_out = dup(1);
Damien Miller994cf142000-07-21 10:19:44 +1000862 startup_pipe = -1;
Damien Millereba71ba2000-04-29 23:57:08 +1000863 /*
864 * We intentionally do not close the descriptors 0, 1, and 2
865 * as our code for setting the descriptors won\'t work if
866 * ttyfd happens to be one of those.
867 */
Damien Miller95def091999-11-25 00:26:21 +1100868 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100869 if (options.protocol & SSH_PROTO_1)
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000870 generate_ephemeral_server_key();
Damien Miller95def091999-11-25 00:26:21 +1100871 } else {
Damien Miller34132e52000-01-14 15:45:46 +1100872 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
873 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
874 continue;
875 if (num_listen_socks >= MAX_LISTEN_SOCKS)
876 fatal("Too many listen sockets. "
877 "Enlarge MAX_LISTEN_SOCKS");
878 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
879 ntop, sizeof(ntop), strport, sizeof(strport),
880 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
881 error("getnameinfo failed");
882 continue;
883 }
884 /* Create socket for listening. */
885 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
886 if (listen_sock < 0) {
887 /* kernel may not support ipv6 */
888 verbose("socket: %.100s", strerror(errno));
889 continue;
890 }
891 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
892 error("listen_sock O_NONBLOCK: %s", strerror(errno));
893 close(listen_sock);
894 continue;
895 }
896 /*
897 * Set socket options. We try to make the port
898 * reusable and have it close as fast as possible
899 * without waiting in unnecessary wait states on
900 * close.
901 */
902 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
903 (void *) &on, sizeof(on));
904 linger.l_onoff = 1;
905 linger.l_linger = 5;
906 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
907 (void *) &linger, sizeof(linger));
Damien Miller95def091999-11-25 00:26:21 +1100908
Damien Miller34132e52000-01-14 15:45:46 +1100909 debug("Bind to port %s on %s.", strport, ntop);
Damien Miller95def091999-11-25 00:26:21 +1100910
Damien Miller34132e52000-01-14 15:45:46 +1100911 /* Bind the socket to the desired port. */
Damien Miller0a4e27d2001-02-18 12:36:39 +1100912 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
913 if (!ai->ai_next)
914 error("Bind to port %s on %s failed: %.200s.",
915 strport, ntop, strerror(errno));
Damien Miller34132e52000-01-14 15:45:46 +1100916 close(listen_sock);
917 continue;
918 }
919 listen_socks[num_listen_socks] = listen_sock;
920 num_listen_socks++;
Damien Miller95def091999-11-25 00:26:21 +1100921
Damien Miller34132e52000-01-14 15:45:46 +1100922 /* Start listening on the port. */
923 log("Server listening on %s port %s.", ntop, strport);
924 if (listen(listen_sock, 5) < 0)
925 fatal("listen: %.100s", strerror(errno));
926
Damien Miller95def091999-11-25 00:26:21 +1100927 }
Damien Miller34132e52000-01-14 15:45:46 +1100928 freeaddrinfo(options.listen_addrs);
929
930 if (!num_listen_socks)
931 fatal("Cannot bind any address.");
932
Ben Lindstrom98097862001-06-25 05:10:20 +0000933 if (options.protocol & SSH_PROTO_1)
934 generate_ephemeral_server_key();
935
936 /*
937 * Arrange to restart on SIGHUP. The handler needs
938 * listen_sock.
939 */
940 signal(SIGHUP, sighup_handler);
941
942 signal(SIGTERM, sigterm_handler);
943 signal(SIGQUIT, sigterm_handler);
944
945 /* Arrange SIGCHLD to be caught. */
946 signal(SIGCHLD, main_sigchld_handler);
947
948 /* Write out the pid file after the sigterm handler is setup */
Damien Miller95def091999-11-25 00:26:21 +1100949 if (!debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +1100950 /*
Ben Lindstrom7ad97102000-12-06 01:42:49 +0000951 * Record our pid in /var/run/sshd.pid to make it
952 * easier to kill the correct sshd. We don't want to
953 * do this before the bind above because the bind will
Damien Miller5428f641999-11-25 11:54:57 +1100954 * fail if there already is a daemon, and this will
955 * overwrite any old pid in the file.
956 */
Damien Millerbac2d8a2000-09-05 16:13:06 +1100957 f = fopen(options.pid_file, "wb");
Damien Miller95def091999-11-25 00:26:21 +1100958 if (f) {
Ben Lindstrom46c16222000-12-22 01:43:59 +0000959 fprintf(f, "%u\n", (u_int) getpid());
Damien Miller95def091999-11-25 00:26:21 +1100960 fclose(f);
961 }
962 }
Damien Miller95def091999-11-25 00:26:21 +1100963
Damien Miller34132e52000-01-14 15:45:46 +1100964 /* setup fd set for listen */
Damien Miller37023962000-07-11 17:31:38 +1000965 fdset = NULL;
Damien Miller34132e52000-01-14 15:45:46 +1100966 maxfd = 0;
967 for (i = 0; i < num_listen_socks; i++)
968 if (listen_socks[i] > maxfd)
969 maxfd = listen_socks[i];
Damien Miller37023962000-07-11 17:31:38 +1000970 /* pipes connected to unauthenticated childs */
971 startup_pipes = xmalloc(options.max_startups * sizeof(int));
972 for (i = 0; i < options.max_startups; i++)
973 startup_pipes[i] = -1;
Damien Miller34132e52000-01-14 15:45:46 +1100974
Damien Miller5428f641999-11-25 11:54:57 +1100975 /*
976 * Stay listening for connections until the system crashes or
977 * the daemon is killed with a signal.
978 */
Damien Miller95def091999-11-25 00:26:21 +1100979 for (;;) {
980 if (received_sighup)
981 sighup_restart();
Damien Miller37023962000-07-11 17:31:38 +1000982 if (fdset != NULL)
983 xfree(fdset);
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000984 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
Damien Miller37023962000-07-11 17:31:38 +1000985 fdset = (fd_set *)xmalloc(fdsetsz);
Damien Miller34132e52000-01-14 15:45:46 +1100986 memset(fdset, 0, fdsetsz);
Damien Miller37023962000-07-11 17:31:38 +1000987
Damien Miller34132e52000-01-14 15:45:46 +1100988 for (i = 0; i < num_listen_socks; i++)
989 FD_SET(listen_socks[i], fdset);
Damien Miller37023962000-07-11 17:31:38 +1000990 for (i = 0; i < options.max_startups; i++)
991 if (startup_pipes[i] != -1)
992 FD_SET(startup_pipes[i], fdset);
993
994 /* Wait in select until there is a connection. */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000995 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
996 if (ret < 0 && errno != EINTR)
997 error("select: %.100s", strerror(errno));
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000998 if (received_sigterm) {
999 log("Received signal %d; terminating.",
Ben Lindstromf8f065b2001-12-06 17:52:16 +00001000 (int) received_sigterm);
Ben Lindstromec46e0b2001-06-09 01:27:31 +00001001 close_listen_socks();
1002 unlink(options.pid_file);
1003 exit(255);
1004 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001005 if (key_used && key_do_regen) {
Ben Lindstromca42d5f2001-03-09 18:25:32 +00001006 generate_ephemeral_server_key();
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001007 key_used = 0;
1008 key_do_regen = 0;
Damien Miller34132e52000-01-14 15:45:46 +11001009 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001010 if (ret < 0)
1011 continue;
1012
Damien Miller37023962000-07-11 17:31:38 +10001013 for (i = 0; i < options.max_startups; i++)
1014 if (startup_pipes[i] != -1 &&
1015 FD_ISSET(startup_pipes[i], fdset)) {
1016 /*
1017 * the read end of the pipe is ready
1018 * if the child has closed the pipe
Ben Lindstrom4dccfa52000-12-28 16:40:05 +00001019 * after successful authentication
Damien Miller37023962000-07-11 17:31:38 +10001020 * or if the child has died
1021 */
1022 close(startup_pipes[i]);
1023 startup_pipes[i] = -1;
1024 startups--;
1025 }
Damien Miller34132e52000-01-14 15:45:46 +11001026 for (i = 0; i < num_listen_socks; i++) {
1027 if (!FD_ISSET(listen_socks[i], fdset))
Damien Miller95def091999-11-25 00:26:21 +11001028 continue;
Damien Miller37023962000-07-11 17:31:38 +10001029 fromlen = sizeof(from);
1030 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1031 &fromlen);
1032 if (newsock < 0) {
1033 if (errno != EINTR && errno != EWOULDBLOCK)
1034 error("accept: %.100s", strerror(errno));
1035 continue;
1036 }
1037 if (fcntl(newsock, F_SETFL, 0) < 0) {
1038 error("newsock del O_NONBLOCK: %s", strerror(errno));
Damien Miller72c336d2001-12-21 12:44:28 +11001039 close(newsock);
Damien Miller37023962000-07-11 17:31:38 +10001040 continue;
1041 }
Damien Miller942da032000-08-18 13:59:06 +10001042 if (drop_connection(startups) == 1) {
1043 debug("drop connection #%d", startups);
Damien Miller37023962000-07-11 17:31:38 +10001044 close(newsock);
1045 continue;
1046 }
1047 if (pipe(startup_p) == -1) {
1048 close(newsock);
1049 continue;
1050 }
1051
1052 for (j = 0; j < options.max_startups; j++)
1053 if (startup_pipes[j] == -1) {
1054 startup_pipes[j] = startup_p[0];
1055 if (maxfd < startup_p[0])
1056 maxfd = startup_p[0];
1057 startups++;
1058 break;
1059 }
Kevin Stevesef4eea92001-02-05 12:42:17 +00001060
Damien Miller5428f641999-11-25 11:54:57 +11001061 /*
Damien Miller37023962000-07-11 17:31:38 +10001062 * Got connection. Fork a child to handle it, unless
1063 * we are in debugging mode.
Damien Miller5428f641999-11-25 11:54:57 +11001064 */
Damien Miller37023962000-07-11 17:31:38 +10001065 if (debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +11001066 /*
Damien Miller37023962000-07-11 17:31:38 +10001067 * In debugging mode. Close the listening
1068 * socket, and start processing the
1069 * connection without forking.
Damien Miller5428f641999-11-25 11:54:57 +11001070 */
Damien Miller37023962000-07-11 17:31:38 +10001071 debug("Server will not fork when running in debugging mode.");
Damien Miller34132e52000-01-14 15:45:46 +11001072 close_listen_socks();
Damien Miller95def091999-11-25 00:26:21 +11001073 sock_in = newsock;
1074 sock_out = newsock;
Damien Miller4d97ba22000-07-11 18:15:50 +10001075 startup_pipe = -1;
Damien Miller182ee6e2000-07-12 09:45:27 +10001076 pid = getpid();
Damien Miller95def091999-11-25 00:26:21 +11001077 break;
Damien Miller37023962000-07-11 17:31:38 +10001078 } else {
1079 /*
1080 * Normal production daemon. Fork, and have
1081 * the child process the connection. The
1082 * parent continues listening.
1083 */
1084 if ((pid = fork()) == 0) {
1085 /*
1086 * Child. Close the listening and max_startup
1087 * sockets. Start using the accepted socket.
1088 * Reinitialize logging (since our pid has
1089 * changed). We break out of the loop to handle
1090 * the connection.
1091 */
1092 startup_pipe = startup_p[1];
Ben Lindstromd84df982001-12-06 16:35:40 +00001093 close_startup_pipes();
Damien Miller37023962000-07-11 17:31:38 +10001094 close_listen_socks();
1095 sock_in = newsock;
1096 sock_out = newsock;
Kevin Stevesec84dc12000-12-13 17:45:15 +00001097 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller37023962000-07-11 17:31:38 +10001098 break;
1099 }
Damien Miller95def091999-11-25 00:26:21 +11001100 }
Damien Miller37023962000-07-11 17:31:38 +10001101
1102 /* Parent. Stay in the loop. */
1103 if (pid < 0)
1104 error("fork: %.100s", strerror(errno));
1105 else
1106 debug("Forked child %d.", pid);
1107
1108 close(startup_p[1]);
1109
1110 /* Mark that the key has been used (it was "given" to the child). */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001111 if ((options.protocol & SSH_PROTO_1) &&
1112 key_used == 0) {
1113 /* Schedule server key regeneration alarm. */
1114 signal(SIGALRM, key_regeneration_alarm);
1115 alarm(options.key_regeneration_time);
1116 key_used = 1;
1117 }
Damien Miller37023962000-07-11 17:31:38 +10001118
1119 arc4random_stir();
1120
1121 /* Close the new socket (the child is now taking care of it). */
1122 close(newsock);
Damien Miller95def091999-11-25 00:26:21 +11001123 }
Damien Miller34132e52000-01-14 15:45:46 +11001124 /* child process check (or debug mode) */
1125 if (num_listen_socks < 0)
1126 break;
Damien Miller95def091999-11-25 00:26:21 +11001127 }
1128 }
1129
1130 /* This is the child processing a new connection. */
1131
Damien Miller5428f641999-11-25 11:54:57 +11001132 /*
1133 * Disable the key regeneration alarm. We will not regenerate the
1134 * key since we are no longer in a position to give it to anyone. We
1135 * will not restart on SIGHUP since it no longer makes sense.
1136 */
Damien Miller95def091999-11-25 00:26:21 +11001137 alarm(0);
1138 signal(SIGALRM, SIG_DFL);
1139 signal(SIGHUP, SIG_DFL);
1140 signal(SIGTERM, SIG_DFL);
1141 signal(SIGQUIT, SIG_DFL);
1142 signal(SIGCHLD, SIG_DFL);
Damien Miller4e0f5e12000-08-29 11:05:50 +11001143 signal(SIGINT, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +11001144
Damien Miller5428f641999-11-25 11:54:57 +11001145 /*
1146 * Set socket options for the connection. We want the socket to
1147 * close as fast as possible without waiting for anything. If the
1148 * connection is not a socket, these will do nothing.
1149 */
1150 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
Damien Miller95def091999-11-25 00:26:21 +11001151 linger.l_onoff = 1;
1152 linger.l_linger = 5;
1153 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1154
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001155 /* Set keepalives if requested. */
1156 if (options.keepalives &&
1157 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1158 sizeof(on)) < 0)
1159 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1160
Damien Miller5428f641999-11-25 11:54:57 +11001161 /*
1162 * Register our connection. This turns encryption off because we do
1163 * not have a key.
1164 */
Damien Miller95def091999-11-25 00:26:21 +11001165 packet_set_connection(sock_in, sock_out);
1166
1167 remote_port = get_remote_port();
1168 remote_ip = get_remote_ipaddr();
1169
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001170#ifdef LIBWRAP
Damien Miller6a4a4b92001-11-12 11:07:11 +11001171 /* Check whether logins are denied from this host. */
Damien Miller95def091999-11-25 00:26:21 +11001172 {
1173 struct request_info req;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001174
Ben Lindstromce89dac2001-09-12 16:58:04 +00001175 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
Damien Miller95def091999-11-25 00:26:21 +11001176 fromhost(&req);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001177
Damien Miller95def091999-11-25 00:26:21 +11001178 if (!hosts_access(&req)) {
Damien Miller6a4a4b92001-11-12 11:07:11 +11001179 debug("Connection refused by tcp wrapper");
Ben Lindstrom7de696e2001-03-29 00:45:12 +00001180 refuse(&req);
Damien Miller6a4a4b92001-11-12 11:07:11 +11001181 /* NOTREACHED */
1182 fatal("libwrap refuse returns");
Damien Miller95def091999-11-25 00:26:21 +11001183 }
Damien Miller95def091999-11-25 00:26:21 +11001184 }
Damien Miller34132e52000-01-14 15:45:46 +11001185#endif /* LIBWRAP */
Damien Miller6a4a4b92001-11-12 11:07:11 +11001186
Damien Miller95def091999-11-25 00:26:21 +11001187 /* Log the connection. */
1188 verbose("Connection from %.500s port %d", remote_ip, remote_port);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001189
Damien Miller5428f641999-11-25 11:54:57 +11001190 /*
1191 * We don\'t want to listen forever unless the other side
1192 * successfully authenticates itself. So we set up an alarm which is
1193 * cleared after successful authentication. A limit of zero
1194 * indicates no limit. Note that we don\'t set the alarm in debugging
1195 * mode; it is just annoying to have the server exit just when you
1196 * are about to discover the bug.
1197 */
Damien Miller95def091999-11-25 00:26:21 +11001198 signal(SIGALRM, grace_alarm_handler);
1199 if (!debug_flag)
1200 alarm(options.login_grace_time);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001201
Damien Millerb38eff82000-04-01 11:09:21 +10001202 sshd_exchange_identification(sock_in, sock_out);
Damien Miller5428f641999-11-25 11:54:57 +11001203 /*
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001204 * Check that the connection comes from a privileged port.
1205 * Rhosts-Authentication only makes sense from priviledged
Damien Miller5428f641999-11-25 11:54:57 +11001206 * programs. Of course, if the intruder has root access on his local
1207 * machine, he can connect from any port. So do not use these
1208 * authentication methods from machines that you do not trust.
1209 */
Damien Miller654c03f2002-02-13 13:54:44 +11001210 if (options.rhosts_authentication &&
1211 (remote_port >= IPPORT_RESERVED ||
1212 remote_port < IPPORT_RESERVED / 2)) {
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001213 debug("Rhosts Authentication disabled, "
Damien Miller00b61642001-11-12 10:51:23 +11001214 "originating port %d not trusted.", remote_port);
Damien Miller95def091999-11-25 00:26:21 +11001215 options.rhosts_authentication = 0;
Damien Miller95def091999-11-25 00:26:21 +11001216 }
Ben Lindstromec95ed92001-07-04 04:21:14 +00001217#if defined(KRB4) && !defined(KRB5)
Damien Miller34132e52000-01-14 15:45:46 +11001218 if (!packet_connection_is_ipv4() &&
1219 options.kerberos_authentication) {
1220 debug("Kerberos Authentication disabled, only available for IPv4.");
1221 options.kerberos_authentication = 0;
1222 }
Ben Lindstromec95ed92001-07-04 04:21:14 +00001223#endif /* KRB4 && !KRB5 */
Ben Lindstromf79aeff2001-02-10 21:27:11 +00001224#ifdef AFS
1225 /* If machine has AFS, set process authentication group. */
1226 if (k_hasafs()) {
1227 k_setpag();
1228 k_unlog();
1229 }
1230#endif /* AFS */
Damien Miller34132e52000-01-14 15:45:46 +11001231
Damien Miller95def091999-11-25 00:26:21 +11001232 packet_set_nonblocking();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001233
Damien Miller396691a2000-01-20 22:44:08 +11001234 /* perform the key exchange */
Damien Miller396691a2000-01-20 22:44:08 +11001235 /* authenticate user and start session */
Damien Millerefb4afe2000-04-12 18:45:05 +10001236 if (compat20) {
1237 do_ssh2_kex();
1238 do_authentication2();
1239 } else {
1240 do_ssh1_kex();
1241 do_authentication();
1242 }
Damien Miller95def091999-11-25 00:26:21 +11001243 /* The connection has been terminated. */
1244 verbose("Closing connection to %.100s", remote_ip);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001245
Damien Millerbeb4ba51999-12-28 15:09:35 +11001246#ifdef USE_PAM
Damien Millere72b7af1999-12-30 15:08:44 +11001247 finish_pam();
Damien Millerbeb4ba51999-12-28 15:09:35 +11001248#endif /* USE_PAM */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001249
Damien Miller95def091999-11-25 00:26:21 +11001250 packet_close();
1251 exit(0);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001252}
1253
Damien Miller95def091999-11-25 00:26:21 +11001254/*
Damien Miller396691a2000-01-20 22:44:08 +11001255 * SSH1 key exchange
Damien Miller95def091999-11-25 00:26:21 +11001256 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001257static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001258do_ssh1_kex(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001259{
Damien Miller95def091999-11-25 00:26:21 +11001260 int i, len;
Damien Miller7650bc62001-01-30 09:27:26 +11001261 int rsafail = 0;
Damien Miller95def091999-11-25 00:26:21 +11001262 BIGNUM *session_key_int;
Ben Lindstrom46c16222000-12-22 01:43:59 +00001263 u_char session_key[SSH_SESSION_KEY_LENGTH];
1264 u_char cookie[8];
1265 u_int cipher_type, auth_mask, protocol_flags;
Damien Miller95def091999-11-25 00:26:21 +11001266 u_int32_t rand = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001267
Damien Miller5428f641999-11-25 11:54:57 +11001268 /*
1269 * Generate check bytes that the client must send back in the user
1270 * packet in order for it to be accepted; this is used to defy ip
1271 * spoofing attacks. Note that this only works against somebody
1272 * doing IP spoofing from a remote machine; any machine on the local
1273 * network can still see outgoing packets and catch the random
1274 * cookie. This only affects rhosts authentication, and this is one
1275 * of the reasons why it is inherently insecure.
1276 */
Damien Miller95def091999-11-25 00:26:21 +11001277 for (i = 0; i < 8; i++) {
1278 if (i % 4 == 0)
1279 rand = arc4random();
Damien Miller396691a2000-01-20 22:44:08 +11001280 cookie[i] = rand & 0xff;
Damien Miller95def091999-11-25 00:26:21 +11001281 rand >>= 8;
1282 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001283
Damien Miller5428f641999-11-25 11:54:57 +11001284 /*
1285 * Send our public key. We include in the packet 64 bits of random
1286 * data that must be matched in the reply in order to prevent IP
1287 * spoofing.
1288 */
Damien Miller95def091999-11-25 00:26:21 +11001289 packet_start(SSH_SMSG_PUBLIC_KEY);
1290 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001291 packet_put_char(cookie[i]);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001292
Damien Miller95def091999-11-25 00:26:21 +11001293 /* Store our public server RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001294 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1295 packet_put_bignum(sensitive_data.server_key->rsa->e);
1296 packet_put_bignum(sensitive_data.server_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001297
Damien Miller95def091999-11-25 00:26:21 +11001298 /* Store our public host RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001299 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1300 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1301 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001302
Damien Miller95def091999-11-25 00:26:21 +11001303 /* Put protocol flags. */
1304 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001305
Damien Miller95def091999-11-25 00:26:21 +11001306 /* Declare which ciphers we support. */
Damien Miller874d77b2000-10-14 16:23:11 +11001307 packet_put_int(cipher_mask_ssh1(0));
Damien Miller95def091999-11-25 00:26:21 +11001308
1309 /* Declare supported authentication types. */
1310 auth_mask = 0;
1311 if (options.rhosts_authentication)
1312 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1313 if (options.rhosts_rsa_authentication)
1314 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1315 if (options.rsa_authentication)
1316 auth_mask |= 1 << SSH_AUTH_RSA;
Ben Lindstromec95ed92001-07-04 04:21:14 +00001317#if defined(KRB4) || defined(KRB5)
Damien Miller95def091999-11-25 00:26:21 +11001318 if (options.kerberos_authentication)
1319 auth_mask |= 1 << SSH_AUTH_KERBEROS;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001320#endif
Ben Lindstromec95ed92001-07-04 04:21:14 +00001321#if defined(AFS) || defined(KRB5)
Damien Miller95def091999-11-25 00:26:21 +11001322 if (options.kerberos_tgt_passing)
1323 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
Ben Lindstromec95ed92001-07-04 04:21:14 +00001324#endif
1325#ifdef AFS
Damien Miller95def091999-11-25 00:26:21 +11001326 if (options.afs_token_passing)
1327 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001328#endif
Ben Lindstrom551ea372001-06-05 18:56:16 +00001329 if (options.challenge_response_authentication == 1)
Damien Miller95def091999-11-25 00:26:21 +11001330 auth_mask |= 1 << SSH_AUTH_TIS;
Damien Miller95def091999-11-25 00:26:21 +11001331 if (options.password_authentication)
1332 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1333 packet_put_int(auth_mask);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001334
Damien Miller95def091999-11-25 00:26:21 +11001335 /* Send the packet and wait for it to be sent. */
1336 packet_send();
1337 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001338
Damien Miller0bc1bd82000-11-13 22:57:25 +11001339 debug("Sent %d bit server key and %d bit host key.",
1340 BN_num_bits(sensitive_data.server_key->rsa->n),
1341 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001342
Damien Miller95def091999-11-25 00:26:21 +11001343 /* Read clients reply (cipher type and session key). */
Damien Millerdff50992002-01-22 23:16:32 +11001344 packet_read_expect(SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001345
Damien Miller50945fa1999-12-09 10:31:37 +11001346 /* Get cipher type and check whether we accept this. */
Damien Miller95def091999-11-25 00:26:21 +11001347 cipher_type = packet_get_char();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001348
Damien Miller874d77b2000-10-14 16:23:11 +11001349 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
Damien Miller50945fa1999-12-09 10:31:37 +11001350 packet_disconnect("Warning: client selects unsupported cipher.");
1351
Damien Miller95def091999-11-25 00:26:21 +11001352 /* Get check bytes from the packet. These must match those we
1353 sent earlier with the public key packet. */
1354 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001355 if (cookie[i] != packet_get_char())
Damien Miller95def091999-11-25 00:26:21 +11001356 packet_disconnect("IP Spoofing check bytes do not match.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001357
Damien Miller95def091999-11-25 00:26:21 +11001358 debug("Encryption type: %.200s", cipher_name(cipher_type));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001359
Damien Miller95def091999-11-25 00:26:21 +11001360 /* Get the encrypted integer. */
Damien Millerda755162002-01-22 23:09:22 +11001361 if ((session_key_int = BN_new()) == NULL)
1362 fatal("do_ssh1_kex: BN_new failed");
Damien Millerd432ccf2002-01-22 23:14:44 +11001363 packet_get_bignum(session_key_int);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001364
Damien Miller95def091999-11-25 00:26:21 +11001365 protocol_flags = packet_get_int();
1366 packet_set_protocol_flags(protocol_flags);
Damien Miller48b03fc2002-01-22 23:11:40 +11001367 packet_check_eom();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001368
Damien Miller5428f641999-11-25 11:54:57 +11001369 /*
1370 * Decrypt it using our private server key and private host key (key
1371 * with larger modulus first).
1372 */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001373 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
Damien Miller7650bc62001-01-30 09:27:26 +11001374 /* Server key has bigger modulus. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001375 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1376 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1377 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1378 get_remote_ipaddr(),
1379 BN_num_bits(sensitive_data.server_key->rsa->n),
1380 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1381 SSH_KEY_BITS_RESERVED);
Damien Miller95def091999-11-25 00:26:21 +11001382 }
Damien Miller7650bc62001-01-30 09:27:26 +11001383 if (rsa_private_decrypt(session_key_int, session_key_int,
1384 sensitive_data.server_key->rsa) <= 0)
1385 rsafail++;
1386 if (rsa_private_decrypt(session_key_int, session_key_int,
1387 sensitive_data.ssh1_host_key->rsa) <= 0)
1388 rsafail++;
Damien Miller95def091999-11-25 00:26:21 +11001389 } else {
1390 /* Host key has bigger modulus (or they are equal). */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001391 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1392 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1393 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1394 get_remote_ipaddr(),
1395 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1396 BN_num_bits(sensitive_data.server_key->rsa->n),
1397 SSH_KEY_BITS_RESERVED);
Damien Miller95def091999-11-25 00:26:21 +11001398 }
Damien Miller7650bc62001-01-30 09:27:26 +11001399 if (rsa_private_decrypt(session_key_int, session_key_int,
1400 sensitive_data.ssh1_host_key->rsa) < 0)
1401 rsafail++;
1402 if (rsa_private_decrypt(session_key_int, session_key_int,
1403 sensitive_data.server_key->rsa) < 0)
1404 rsafail++;
Damien Miller95def091999-11-25 00:26:21 +11001405 }
Damien Miller5428f641999-11-25 11:54:57 +11001406 /*
1407 * Extract session key from the decrypted integer. The key is in the
1408 * least significant 256 bits of the integer; the first byte of the
1409 * key is in the highest bits.
1410 */
Damien Miller7650bc62001-01-30 09:27:26 +11001411 if (!rsafail) {
1412 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1413 len = BN_num_bytes(session_key_int);
1414 if (len < 0 || len > sizeof(session_key)) {
1415 error("do_connection: bad session key len from %s: "
Ben Lindstrom31ca54a2001-02-09 02:11:24 +00001416 "session_key_int %d > sizeof(session_key) %lu",
1417 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
Damien Miller7650bc62001-01-30 09:27:26 +11001418 rsafail++;
1419 } else {
1420 memset(session_key, 0, sizeof(session_key));
1421 BN_bn2bin(session_key_int,
1422 session_key + sizeof(session_key) - len);
Ben Lindstromeb648a72001-03-05 06:00:29 +00001423
1424 compute_session_id(session_id, cookie,
1425 sensitive_data.ssh1_host_key->rsa->n,
1426 sensitive_data.server_key->rsa->n);
1427 /*
1428 * Xor the first 16 bytes of the session key with the
1429 * session id.
1430 */
1431 for (i = 0; i < 16; i++)
1432 session_key[i] ^= session_id[i];
Damien Miller7650bc62001-01-30 09:27:26 +11001433 }
1434 }
1435 if (rsafail) {
Ben Lindstromeb648a72001-03-05 06:00:29 +00001436 int bytes = BN_num_bytes(session_key_int);
1437 char *buf = xmalloc(bytes);
1438 MD5_CTX md;
1439
Damien Miller7650bc62001-01-30 09:27:26 +11001440 log("do_connection: generating a fake encryption key");
Ben Lindstromeb648a72001-03-05 06:00:29 +00001441 BN_bn2bin(session_key_int, buf);
1442 MD5_Init(&md);
1443 MD5_Update(&md, buf, bytes);
1444 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1445 MD5_Final(session_key, &md);
1446 MD5_Init(&md);
1447 MD5_Update(&md, session_key, 16);
1448 MD5_Update(&md, buf, bytes);
1449 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1450 MD5_Final(session_key + 16, &md);
1451 memset(buf, 0, bytes);
1452 xfree(buf);
Ben Lindstrom941ac822001-03-05 06:25:23 +00001453 for (i = 0; i < 16; i++)
1454 session_id[i] = session_key[i] ^ session_key[i + 16];
Damien Miller7650bc62001-01-30 09:27:26 +11001455 }
Ben Lindstromeb648a72001-03-05 06:00:29 +00001456 /* Destroy the private and public keys. They will no longer be needed. */
1457 destroy_sensitive_data();
1458
Damien Miller396691a2000-01-20 22:44:08 +11001459 /* Destroy the decrypted integer. It is no longer needed. */
1460 BN_clear_free(session_key_int);
1461
Damien Miller95def091999-11-25 00:26:21 +11001462 /* Set the session key. From this on all communications will be encrypted. */
1463 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001464
Damien Miller95def091999-11-25 00:26:21 +11001465 /* Destroy our copy of the session key. It is no longer needed. */
1466 memset(session_key, 0, sizeof(session_key));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001467
Damien Miller95def091999-11-25 00:26:21 +11001468 debug("Received session key; encryption turned on.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001469
Damien Miller95def091999-11-25 00:26:21 +11001470 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1471 packet_start(SSH_SMSG_SUCCESS);
1472 packet_send();
1473 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001474}
Damien Millerefb4afe2000-04-12 18:45:05 +10001475
1476/*
1477 * SSH2 key exchange: diffie-hellman-group1-sha1
1478 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001479static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001480do_ssh2_kex(void)
Damien Millerefb4afe2000-04-12 18:45:05 +10001481{
Damien Millerefb4afe2000-04-12 18:45:05 +10001482 Kex *kex;
Damien Millerefb4afe2000-04-12 18:45:05 +10001483
Damien Miller78928792000-04-12 20:17:38 +10001484 if (options.ciphers != NULL) {
Damien Miller4af51302000-04-16 11:18:38 +10001485 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
Damien Miller78928792000-04-12 20:17:38 +10001486 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1487 }
Damien Millera0ff4662001-03-30 10:49:35 +10001488 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1489 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1490 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1491 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1492
Ben Lindstrom06b33aa2001-02-15 03:01:59 +00001493 if (options.macs != NULL) {
1494 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1495 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1496 }
Damien Miller0bc1bd82000-11-13 22:57:25 +11001497 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1498
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001499 /* start key exchange */
Ben Lindstrom238abf62001-04-04 17:52:53 +00001500 kex = kex_setup(myproposal);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001501 kex->server = 1;
1502 kex->client_version_string=client_version_string;
1503 kex->server_version_string=server_version_string;
1504 kex->load_host_key=&get_hostkey_by_type;
Damien Millerefb4afe2000-04-12 18:45:05 +10001505
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001506 xxx_kex = kex;
1507
Ben Lindstrombe2cc432001-04-04 23:46:07 +00001508 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
Damien Miller874d77b2000-10-14 16:23:11 +11001509
Ben Lindstrom2d90e002001-04-04 02:00:54 +00001510 session_id2 = kex->session_id;
1511 session_id2_len = kex->session_id_len;
1512
Damien Miller874d77b2000-10-14 16:23:11 +11001513#ifdef DEBUG_KEXDH
1514 /* send 1st encrypted/maced/compressed message */
1515 packet_start(SSH2_MSG_IGNORE);
1516 packet_put_cstring("markus");
1517 packet_send();
1518 packet_write_wait();
1519#endif
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001520 debug("KEX done");
Damien Millerefb4afe2000-04-12 18:45:05 +10001521}