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Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller95def091999-11-25 00:26:21 +11002 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
Damien Millere4340be2000-09-16 13:29:08 +11005 * This program is the ssh daemon. It listens for connections from clients,
6 * and performs authentication, executes use commands or shell, and forwards
Damien Miller95def091999-11-25 00:26:21 +11007 * information to/from the application to the user client over an encrypted
Damien Millere4340be2000-09-16 13:29:08 +11008 * connection. This can also handle forwarding of X11, TCP/IP, and
9 * authentication agent connections.
Damien Millerefb4afe2000-04-12 18:45:05 +100010 *
Damien Millere4340be2000-09-16 13:29:08 +110011 * As far as I am concerned, the code I have written for this software
12 * can be used freely for any purpose. Any derived versions of this
13 * software must be clearly marked as such, and if the derived work is
14 * incompatible with the protocol description in the RFC file, it must be
15 * called by a name other than "ssh" or "Secure Shell".
16 *
17 * SSH2 implementation:
18 *
19 * Copyright (c) 2000 Markus Friedl. All rights reserved.
20 *
21 * Redistribution and use in source and binary forms, with or without
22 * modification, are permitted provided that the following conditions
23 * are met:
24 * 1. Redistributions of source code must retain the above copyright
25 * notice, this list of conditions and the following disclaimer.
26 * 2. Redistributions in binary form must reproduce the above copyright
27 * notice, this list of conditions and the following disclaimer in the
28 * documentation and/or other materials provided with the distribution.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
31 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
33 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
34 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
35 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
39 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Damien Miller95def091999-11-25 00:26:21 +110040 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100041
42#include "includes.h"
Ben Lindstrom1bae4042001-10-03 17:46:39 +000043RCSID("$OpenBSD: sshd.c,v 1.206 2001/10/02 22:56:09 stevesk 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 Lindstromdb65e8f2001-01-19 04:26:52 +0000172int 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. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000175int received_sighup = 0;
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000176int 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
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000188/* Prototypes for various functions defined later in this file. */
Ben Lindstrombba81212001-06-25 05:01:22 +0000189void destroy_sensitive_data(void);
Damien Miller98c7ad62000-03-09 21:27:49 +1100190
Ben Lindstrombba81212001-06-25 05:01:22 +0000191static void do_ssh1_kex(void);
192static void do_ssh2_kex(void);
Damien Miller874d77b2000-10-14 16:23:11 +1100193
Damien Miller98c7ad62000-03-09 21:27:49 +1100194/*
Damien Miller34132e52000-01-14 15:45:46 +1100195 * Close all listening sockets
196 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000197static void
Damien Miller34132e52000-01-14 15:45:46 +1100198close_listen_socks(void)
199{
200 int i;
201 for (i = 0; i < num_listen_socks; i++)
202 close(listen_socks[i]);
203 num_listen_socks = -1;
204}
205
206/*
Damien Miller95def091999-11-25 00:26:21 +1100207 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
208 * the effect is to reread the configuration file (and to regenerate
209 * the server key).
210 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000211static void
Damien Miller95def091999-11-25 00:26:21 +1100212sighup_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000213{
Damien Miller95def091999-11-25 00:26:21 +1100214 received_sighup = 1;
215 signal(SIGHUP, sighup_handler);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000216}
217
Damien Miller95def091999-11-25 00:26:21 +1100218/*
219 * Called from the main program after receiving SIGHUP.
220 * Restarts the server.
221 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000222static void
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000223sighup_restart(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000224{
Damien Miller95def091999-11-25 00:26:21 +1100225 log("Received SIGHUP; restarting.");
Damien Miller34132e52000-01-14 15:45:46 +1100226 close_listen_socks();
Damien Miller95def091999-11-25 00:26:21 +1100227 execv(saved_argv[0], saved_argv);
Kevin Stevesec84dc12000-12-13 17:45:15 +0000228 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100229 exit(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000230}
231
Damien Miller95def091999-11-25 00:26:21 +1100232/*
233 * Generic signal handler for terminating signals in the master daemon.
Damien Miller95def091999-11-25 00:26:21 +1100234 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000235static void
Damien Miller95def091999-11-25 00:26:21 +1100236sigterm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000237{
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000238 received_sigterm = sig;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000239}
240
Damien Miller95def091999-11-25 00:26:21 +1100241/*
242 * SIGCHLD handler. This is called whenever a child dies. This will then
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000243 * reap any zombies left by exited children.
Damien Miller95def091999-11-25 00:26:21 +1100244 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000245static void
Damien Miller95def091999-11-25 00:26:21 +1100246main_sigchld_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000247{
Damien Miller95def091999-11-25 00:26:21 +1100248 int save_errno = errno;
249 int status;
Damien Miller431f66b1999-11-21 18:31:57 +1100250
Damien Miller95def091999-11-25 00:26:21 +1100251 while (waitpid(-1, &status, WNOHANG) > 0)
252 ;
Damien Miller431f66b1999-11-21 18:31:57 +1100253
Damien Miller95def091999-11-25 00:26:21 +1100254 signal(SIGCHLD, main_sigchld_handler);
255 errno = save_errno;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000256}
257
Damien Miller95def091999-11-25 00:26:21 +1100258/*
259 * Signal handler for the alarm after the login grace period has expired.
260 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000261static void
Damien Miller95def091999-11-25 00:26:21 +1100262grace_alarm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000263{
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000264 /* XXX no idea how fix this signal handler */
265
Damien Miller95def091999-11-25 00:26:21 +1100266 /* Close the connection. */
267 packet_close();
268
269 /* Log error and exit. */
270 fatal("Timeout before authentication for %s.", get_remote_ipaddr());
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000271}
272
Damien Miller95def091999-11-25 00:26:21 +1100273/*
Damien Miller95def091999-11-25 00:26:21 +1100274 * Signal handler for the key regeneration alarm. Note that this
275 * alarm only occurs in the daemon waiting for connections, and it does not
276 * do anything with the private key or random state before forking.
277 * Thus there should be no concurrency control/asynchronous execution
278 * problems.
279 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000280static void
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000281generate_ephemeral_server_key(void)
Damien Miller0bc1bd82000-11-13 22:57:25 +1100282{
Ben Lindstromeb648a72001-03-05 06:00:29 +0000283 u_int32_t rand = 0;
284 int i;
285
Ben Lindstroma3700052001-04-05 23:26:32 +0000286 verbose("Generating %s%d bit RSA key.",
Damien Millerff75ac42001-03-30 10:50:32 +1000287 sensitive_data.server_key ? "new " : "", options.server_key_bits);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100288 if (sensitive_data.server_key != NULL)
289 key_free(sensitive_data.server_key);
Ben Lindstroma3700052001-04-05 23:26:32 +0000290 sensitive_data.server_key = key_generate(KEY_RSA1,
Damien Millerff75ac42001-03-30 10:50:32 +1000291 options.server_key_bits);
292 verbose("RSA key generation complete.");
Ben Lindstromeb648a72001-03-05 06:00:29 +0000293
294 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
295 if (i % 4 == 0)
296 rand = arc4random();
297 sensitive_data.ssh1_cookie[i] = rand & 0xff;
298 rand >>= 8;
299 }
300 arc4random_stir();
Damien Miller0bc1bd82000-11-13 22:57:25 +1100301}
Ben Lindstrom2f959b42001-01-11 06:20:23 +0000302
Ben Lindstrombba81212001-06-25 05:01:22 +0000303static void
Damien Miller95def091999-11-25 00:26:21 +1100304key_regeneration_alarm(int sig)
305{
306 int save_errno = errno;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000307 signal(SIGALRM, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +1100308 errno = save_errno;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000309 key_do_regen = 1;
Damien Miller95def091999-11-25 00:26:21 +1100310}
311
Ben Lindstrombba81212001-06-25 05:01:22 +0000312static void
Damien Millerb38eff82000-04-01 11:09:21 +1000313sshd_exchange_identification(int sock_in, int sock_out)
314{
Damien Miller78928792000-04-12 20:17:38 +1000315 int i, mismatch;
Damien Millerb38eff82000-04-01 11:09:21 +1000316 int remote_major, remote_minor;
Damien Miller78928792000-04-12 20:17:38 +1000317 int major, minor;
Damien Millerb38eff82000-04-01 11:09:21 +1000318 char *s;
319 char buf[256]; /* Must not be larger than remote_version. */
320 char remote_version[256]; /* Must be at least as big as buf. */
321
Damien Miller78928792000-04-12 20:17:38 +1000322 if ((options.protocol & SSH_PROTO_1) &&
323 (options.protocol & SSH_PROTO_2)) {
324 major = PROTOCOL_MAJOR_1;
325 minor = 99;
326 } else if (options.protocol & SSH_PROTO_2) {
327 major = PROTOCOL_MAJOR_2;
328 minor = PROTOCOL_MINOR_2;
329 } else {
330 major = PROTOCOL_MAJOR_1;
331 minor = PROTOCOL_MINOR_1;
332 }
333 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
Damien Millerb38eff82000-04-01 11:09:21 +1000334 server_version_string = xstrdup(buf);
335
336 if (client_version_string == NULL) {
337 /* Send our protocol version identification. */
338 if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
339 != strlen(server_version_string)) {
340 log("Could not write ident string to %s.", get_remote_ipaddr());
341 fatal_cleanup();
342 }
343
Ben Lindstrom5393f932001-02-15 03:17:13 +0000344 /* Read other side's version identification. */
Ben Lindstroma3700052001-04-05 23:26:32 +0000345 memset(buf, 0, sizeof(buf));
Damien Millerb38eff82000-04-01 11:09:21 +1000346 for (i = 0; i < sizeof(buf) - 1; i++) {
Damien Millerbf7f4662000-06-23 10:16:38 +1000347 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
Ben Lindstroma9a29e12001-02-20 01:20:47 +0000348 log("Did not receive identification string from %s.",
349 get_remote_ipaddr());
Damien Millerb38eff82000-04-01 11:09:21 +1000350 fatal_cleanup();
351 }
352 if (buf[i] == '\r') {
Ben Lindstrom69d8c072001-03-22 22:45:33 +0000353 buf[i] = 0;
Damien Miller874d77b2000-10-14 16:23:11 +1100354 /* Kludge for F-Secure Macintosh < 1.0.2 */
355 if (i == 12 &&
356 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
357 break;
Damien Millerb38eff82000-04-01 11:09:21 +1000358 continue;
Damien Millerb38eff82000-04-01 11:09:21 +1000359 }
360 if (buf[i] == '\n') {
Ben Lindstrom69d8c072001-03-22 22:45:33 +0000361 buf[i] = 0;
Damien Millerb38eff82000-04-01 11:09:21 +1000362 break;
363 }
364 }
365 buf[sizeof(buf) - 1] = 0;
366 client_version_string = xstrdup(buf);
367 }
368
369 /*
370 * Check that the versions match. In future this might accept
371 * several versions and set appropriate flags to handle them.
372 */
373 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
374 &remote_major, &remote_minor, remote_version) != 3) {
Damien Miller4af51302000-04-16 11:18:38 +1000375 s = "Protocol mismatch.\n";
Damien Millerb38eff82000-04-01 11:09:21 +1000376 (void) atomicio(write, sock_out, s, strlen(s));
377 close(sock_in);
378 close(sock_out);
379 log("Bad protocol version identification '%.100s' from %s",
380 client_version_string, get_remote_ipaddr());
381 fatal_cleanup();
382 }
383 debug("Client protocol version %d.%d; client software version %.100s",
384 remote_major, remote_minor, remote_version);
385
Damien Millerefb4afe2000-04-12 18:45:05 +1000386 compat_datafellows(remote_version);
387
Damien Miller27dbe6f2001-03-19 22:36:20 +1100388 if (datafellows & SSH_BUG_SCANNER) {
389 log("scanned from %s with %s. Don't panic.",
390 get_remote_ipaddr(), client_version_string);
391 fatal_cleanup();
392 }
393
Damien Miller78928792000-04-12 20:17:38 +1000394 mismatch = 0;
Damien Millerb38eff82000-04-01 11:09:21 +1000395 switch(remote_major) {
396 case 1:
Damien Millereba71ba2000-04-29 23:57:08 +1000397 if (remote_minor == 99) {
398 if (options.protocol & SSH_PROTO_2)
399 enable_compat20();
400 else
401 mismatch = 1;
402 break;
403 }
Damien Miller78928792000-04-12 20:17:38 +1000404 if (!(options.protocol & SSH_PROTO_1)) {
405 mismatch = 1;
406 break;
407 }
Damien Millerb38eff82000-04-01 11:09:21 +1000408 if (remote_minor < 3) {
Damien Miller37023962000-07-11 17:31:38 +1000409 packet_disconnect("Your ssh version is too old and "
Damien Millerb38eff82000-04-01 11:09:21 +1000410 "is no longer supported. Please install a newer version.");
411 } else if (remote_minor == 3) {
412 /* note that this disables agent-forwarding */
413 enable_compat13();
414 }
Damien Miller78928792000-04-12 20:17:38 +1000415 break;
Damien Millerefb4afe2000-04-12 18:45:05 +1000416 case 2:
Damien Miller78928792000-04-12 20:17:38 +1000417 if (options.protocol & SSH_PROTO_2) {
Damien Millerefb4afe2000-04-12 18:45:05 +1000418 enable_compat20();
419 break;
420 }
421 /* FALLTHROUGH */
Damien Miller4af51302000-04-16 11:18:38 +1000422 default:
Damien Miller78928792000-04-12 20:17:38 +1000423 mismatch = 1;
Damien Millerb38eff82000-04-01 11:09:21 +1000424 break;
425 }
Damien Millerefb4afe2000-04-12 18:45:05 +1000426 chop(server_version_string);
Damien Miller78928792000-04-12 20:17:38 +1000427 debug("Local version string %.200s", server_version_string);
428
429 if (mismatch) {
430 s = "Protocol major versions differ.\n";
431 (void) atomicio(write, sock_out, s, strlen(s));
432 close(sock_in);
433 close(sock_out);
434 log("Protocol major versions differ for %s: %.200s vs. %.200s",
435 get_remote_ipaddr(),
436 server_version_string, client_version_string);
437 fatal_cleanup();
438 }
Damien Millereba71ba2000-04-29 23:57:08 +1000439}
440
441
Damien Miller0bc1bd82000-11-13 22:57:25 +1100442/* Destroy the host and server keys. They will no longer be needed. */
Damien Millereba71ba2000-04-29 23:57:08 +1000443void
444destroy_sensitive_data(void)
445{
Damien Miller0bc1bd82000-11-13 22:57:25 +1100446 int i;
447
448 if (sensitive_data.server_key) {
449 key_free(sensitive_data.server_key);
450 sensitive_data.server_key = NULL;
451 }
Kevin Stevesef4eea92001-02-05 12:42:17 +0000452 for(i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100453 if (sensitive_data.host_keys[i]) {
454 key_free(sensitive_data.host_keys[i]);
455 sensitive_data.host_keys[i] = NULL;
456 }
457 }
458 sensitive_data.ssh1_host_key = NULL;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000459 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100460}
Damien Miller0bc1bd82000-11-13 22:57:25 +1100461
Ben Lindstrombba81212001-06-25 05:01:22 +0000462static char *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100463list_hostkey_types(void)
464{
465 static char buf[1024];
466 int i;
467 buf[0] = '\0';
468 for(i = 0; i < options.num_host_key_files; i++) {
469 Key *key = sensitive_data.host_keys[i];
470 if (key == NULL)
471 continue;
472 switch(key->type) {
473 case KEY_RSA:
474 case KEY_DSA:
475 strlcat(buf, key_ssh_name(key), sizeof buf);
476 strlcat(buf, ",", sizeof buf);
477 break;
478 }
479 }
480 i = strlen(buf);
481 if (i > 0 && buf[i-1] == ',')
482 buf[i-1] = '\0';
483 debug("list_hostkey_types: %s", buf);
484 return buf;
485}
486
Ben Lindstrombba81212001-06-25 05:01:22 +0000487static Key *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100488get_hostkey_by_type(int type)
489{
490 int i;
491 for(i = 0; i < options.num_host_key_files; i++) {
492 Key *key = sensitive_data.host_keys[i];
493 if (key != NULL && key->type == type)
494 return key;
495 }
496 return NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000497}
498
Damien Miller942da032000-08-18 13:59:06 +1000499/*
500 * returns 1 if connection should be dropped, 0 otherwise.
501 * dropping starts at connection #max_startups_begin with a probability
502 * of (max_startups_rate/100). the probability increases linearly until
503 * all connections are dropped for startups > max_startups
504 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000505static int
Damien Miller942da032000-08-18 13:59:06 +1000506drop_connection(int startups)
507{
508 double p, r;
509
510 if (startups < options.max_startups_begin)
511 return 0;
512 if (startups >= options.max_startups)
513 return 1;
514 if (options.max_startups_rate == 100)
515 return 1;
516
517 p = 100 - options.max_startups_rate;
518 p *= startups - options.max_startups_begin;
519 p /= (double) (options.max_startups - options.max_startups_begin);
520 p += options.max_startups_rate;
521 p /= 100.0;
522 r = arc4random() / (double) UINT_MAX;
523
524 debug("drop_connection: p %g, r %g", p, r);
525 return (r < p) ? 1 : 0;
526}
527
Damien Miller37023962000-07-11 17:31:38 +1000528int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
529int startup_pipe; /* in child */
530
Damien Miller95def091999-11-25 00:26:21 +1100531/*
532 * Main program for the daemon.
533 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000534int
535main(int ac, char **av)
536{
Damien Miller95def091999-11-25 00:26:21 +1100537 extern char *optarg;
538 extern int optind;
Damien Miller37023962000-07-11 17:31:38 +1000539 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
Damien Miller166fca82000-04-20 07:42:21 +1000540 pid_t pid;
Damien Miller34132e52000-01-14 15:45:46 +1100541 socklen_t fromlen;
Damien Miller34132e52000-01-14 15:45:46 +1100542 fd_set *fdset;
543 struct sockaddr_storage from;
Damien Miller95def091999-11-25 00:26:21 +1100544 const char *remote_ip;
545 int remote_port;
Damien Miller95def091999-11-25 00:26:21 +1100546 FILE *f;
547 struct linger linger;
Damien Miller34132e52000-01-14 15:45:46 +1100548 struct addrinfo *ai;
549 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
550 int listen_sock, maxfd;
Damien Miller37023962000-07-11 17:31:38 +1000551 int startup_p[2];
552 int startups = 0;
Ben Lindstromd0fca422001-03-26 13:44:06 +0000553 Key *key;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000554 int ret, key_used = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000555
Ben Lindstrom49a79c02000-11-17 03:47:20 +0000556 __progname = get_progname(av[0]);
Damien Millerf9b625c2000-07-09 22:42:32 +1000557 init_rng();
558
Kevin Stevesec84dc12000-12-13 17:45:15 +0000559 /* Save argv. */
Damien Millerb8c656e2000-06-28 15:22:41 +1000560 saved_argc = ac;
Damien Miller95def091999-11-25 00:26:21 +1100561 saved_argv = av;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000562
Damien Miller95def091999-11-25 00:26:21 +1100563 /* Initialize configuration options to their default values. */
564 initialize_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000565
Damien Miller95def091999-11-25 00:26:21 +1100566 /* Parse command-line arguments. */
Ben Lindstrom794325a2001-08-06 21:09:07 +0000567 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDeiqtQ46")) != -1) {
Damien Miller95def091999-11-25 00:26:21 +1100568 switch (opt) {
Damien Miller34132e52000-01-14 15:45:46 +1100569 case '4':
570 IPv4or6 = AF_INET;
571 break;
572 case '6':
573 IPv4or6 = AF_INET6;
574 break;
Damien Miller95def091999-11-25 00:26:21 +1100575 case 'f':
576 config_file_name = optarg;
577 break;
578 case 'd':
Damien Millere4340be2000-09-16 13:29:08 +1100579 if (0 == debug_flag) {
580 debug_flag = 1;
581 options.log_level = SYSLOG_LEVEL_DEBUG1;
582 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
583 options.log_level++;
584 } else {
585 fprintf(stderr, "Too high debugging level.\n");
586 exit(1);
587 }
Damien Miller95def091999-11-25 00:26:21 +1100588 break;
Ben Lindstromc72745a2000-12-02 19:03:54 +0000589 case 'D':
590 no_daemon_flag = 1;
591 break;
Ben Lindstrom9fce9f02001-04-11 23:10:09 +0000592 case 'e':
593 log_stderr = 1;
594 break;
Damien Miller95def091999-11-25 00:26:21 +1100595 case 'i':
596 inetd_flag = 1;
597 break;
598 case 'Q':
Ben Lindstromd5390202001-01-29 08:07:43 +0000599 /* ignored */
Damien Miller95def091999-11-25 00:26:21 +1100600 break;
601 case 'q':
602 options.log_level = SYSLOG_LEVEL_QUIET;
603 break;
604 case 'b':
605 options.server_key_bits = atoi(optarg);
606 break;
607 case 'p':
Damien Miller34132e52000-01-14 15:45:46 +1100608 options.ports_from_cmdline = 1;
Damien Millere4340be2000-09-16 13:29:08 +1100609 if (options.num_ports >= MAX_PORTS) {
610 fprintf(stderr, "too many ports.\n");
611 exit(1);
612 }
Ben Lindstrom19066a12001-04-12 23:39:26 +0000613 options.ports[options.num_ports++] = a2port(optarg);
614 if (options.ports[options.num_ports-1] == 0) {
615 fprintf(stderr, "Bad port number.\n");
616 exit(1);
617 }
Damien Miller95def091999-11-25 00:26:21 +1100618 break;
619 case 'g':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000620 if ((options.login_grace_time = convtime(optarg)) == -1) {
621 fprintf(stderr, "Invalid login grace time.\n");
622 exit(1);
623 }
Damien Miller95def091999-11-25 00:26:21 +1100624 break;
625 case 'k':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000626 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
627 fprintf(stderr, "Invalid key regeneration interval.\n");
628 exit(1);
629 }
Damien Miller95def091999-11-25 00:26:21 +1100630 break;
631 case 'h':
Damien Miller0bc1bd82000-11-13 22:57:25 +1100632 if (options.num_host_key_files >= MAX_HOSTKEYS) {
633 fprintf(stderr, "too many host keys.\n");
634 exit(1);
635 }
636 options.host_key_files[options.num_host_key_files++] = optarg;
Damien Miller95def091999-11-25 00:26:21 +1100637 break;
638 case 'V':
639 client_version_string = optarg;
640 /* only makes sense with inetd_flag, i.e. no listen() */
641 inetd_flag = 1;
642 break;
Ben Lindstrom794325a2001-08-06 21:09:07 +0000643 case 't':
644 test_flag = 1;
645 break;
Damien Miller942da032000-08-18 13:59:06 +1000646 case 'u':
647 utmp_len = atoi(optarg);
648 break;
Damien Miller95def091999-11-25 00:26:21 +1100649 case '?':
650 default:
651 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
Kevin Stevesec84dc12000-12-13 17:45:15 +0000652 fprintf(stderr, "Usage: %s [options]\n", __progname);
Damien Miller95def091999-11-25 00:26:21 +1100653 fprintf(stderr, "Options:\n");
Ben Lindstrom226cfa02001-01-22 05:34:40 +0000654 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
Damien Millere4340be2000-09-16 13:29:08 +1100655 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
Damien Miller95def091999-11-25 00:26:21 +1100656 fprintf(stderr, " -i Started from inetd\n");
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000657 fprintf(stderr, " -D Do not fork into daemon mode\n");
Ben Lindstrom794325a2001-08-06 21:09:07 +0000658 fprintf(stderr, " -t Only test configuration file and keys\n");
Damien Miller95def091999-11-25 00:26:21 +1100659 fprintf(stderr, " -q Quiet (no logging)\n");
660 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
661 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
Ben Lindstromd26dcf32001-01-06 15:18:16 +0000662 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
Damien Miller95def091999-11-25 00:26:21 +1100663 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
664 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
Ben Lindstrom226cfa02001-01-22 05:34:40 +0000665 _PATH_HOST_KEY_FILE);
Damien Miller942da032000-08-18 13:59:06 +1000666 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
Damien Miller34132e52000-01-14 15:45:46 +1100667 fprintf(stderr, " -4 Use IPv4 only\n");
668 fprintf(stderr, " -6 Use IPv6 only\n");
Damien Miller95def091999-11-25 00:26:21 +1100669 exit(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000670 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000671 }
Ben Lindstrom425fb022001-03-29 00:31:20 +0000672 SSLeay_add_all_algorithms();
Ben Lindstrom908afed2001-10-03 17:34:59 +0000673 channel_set_af(IPv4or6);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000674
Damien Miller34132e52000-01-14 15:45:46 +1100675 /*
676 * Force logging to stderr until we have loaded the private host
677 * key (unless started from inetd)
678 */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000679 log_init(__progname,
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000680 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
Damien Miller34132e52000-01-14 15:45:46 +1100681 options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
Ben Lindstromd5390202001-01-29 08:07:43 +0000682 !inetd_flag);
Damien Miller34132e52000-01-14 15:45:46 +1100683
Ben Lindstrom6db66ff2001-08-06 23:29:16 +0000684#ifdef _CRAY
685 /* Cray can define user privs drop all prives now!
686 * Not needed on PRIV_SU systems!
687 */
688 drop_cray_privs();
689#endif
690
Damien Miller60bc5172001-03-19 09:38:15 +1100691 seed_rng();
692
Damien Miller95def091999-11-25 00:26:21 +1100693 /* Read server configuration options from the configuration file. */
694 read_server_config(&options, config_file_name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000695
Damien Miller95def091999-11-25 00:26:21 +1100696 /* Fill in default values for those options not explicitly set. */
697 fill_default_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000698
Damien Miller95def091999-11-25 00:26:21 +1100699 /* Check that there are no remaining arguments. */
700 if (optind < ac) {
701 fprintf(stderr, "Extra argument %s.\n", av[optind]);
702 exit(1);
703 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000704
Damien Miller95def091999-11-25 00:26:21 +1100705 debug("sshd version %.100s", SSH_VERSION);
Damien Miller2ccf6611999-11-15 15:25:10 +1100706
Damien Miller0bc1bd82000-11-13 22:57:25 +1100707 /* load private host keys */
708 sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
Ben Lindstrom46c16222000-12-22 01:43:59 +0000709 for(i = 0; i < options.num_host_key_files; i++)
710 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100711 sensitive_data.server_key = NULL;
712 sensitive_data.ssh1_host_key = NULL;
713 sensitive_data.have_ssh1_key = 0;
714 sensitive_data.have_ssh2_key = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000715
Damien Miller0bc1bd82000-11-13 22:57:25 +1100716 for(i = 0; i < options.num_host_key_files; i++) {
Ben Lindstromd0fca422001-03-26 13:44:06 +0000717 key = key_load_private(options.host_key_files[i], "", NULL);
718 sensitive_data.host_keys[i] = key;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100719 if (key == NULL) {
Ben Lindstrom15f33862001-04-16 02:00:02 +0000720 error("Could not load host key: %s",
721 options.host_key_files[i]);
Ben Lindstromd0fca422001-03-26 13:44:06 +0000722 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100723 continue;
724 }
725 switch(key->type){
726 case KEY_RSA1:
727 sensitive_data.ssh1_host_key = key;
728 sensitive_data.have_ssh1_key = 1;
729 break;
730 case KEY_RSA:
731 case KEY_DSA:
732 sensitive_data.have_ssh2_key = 1;
733 break;
734 }
Ben Lindstromd0fca422001-03-26 13:44:06 +0000735 debug("private host key: #%d type %d %s", i, key->type,
736 key_type(key));
Damien Miller0bc1bd82000-11-13 22:57:25 +1100737 }
738 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
739 log("Disabling protocol version 1. Could not load host key");
Damien Millereba71ba2000-04-29 23:57:08 +1000740 options.protocol &= ~SSH_PROTO_1;
741 }
Damien Miller0bc1bd82000-11-13 22:57:25 +1100742 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
743 log("Disabling protocol version 2. Could not load host key");
744 options.protocol &= ~SSH_PROTO_2;
Damien Millereba71ba2000-04-29 23:57:08 +1000745 }
Kevin Stevesadf74cd2001-02-05 14:22:50 +0000746 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
Ben Lindstrom6df8ef42001-03-05 07:47:23 +0000747 log("sshd: no hostkeys available -- exiting.");
Damien Miller95def091999-11-25 00:26:21 +1100748 exit(1);
749 }
Damien Miller95def091999-11-25 00:26:21 +1100750
Damien Millereba71ba2000-04-29 23:57:08 +1000751 /* Check certain values for sanity. */
752 if (options.protocol & SSH_PROTO_1) {
753 if (options.server_key_bits < 512 ||
754 options.server_key_bits > 32768) {
755 fprintf(stderr, "Bad server key size.\n");
756 exit(1);
757 }
758 /*
759 * Check that server and host key lengths differ sufficiently. This
760 * is necessary to make double encryption work with rsaref. Oh, I
761 * hate software patents. I dont know if this can go? Niels
762 */
763 if (options.server_key_bits >
Damien Miller0bc1bd82000-11-13 22:57:25 +1100764 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
Damien Millereba71ba2000-04-29 23:57:08 +1000765 options.server_key_bits <
Damien Miller0bc1bd82000-11-13 22:57:25 +1100766 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
Damien Millereba71ba2000-04-29 23:57:08 +1000767 options.server_key_bits =
Damien Miller0bc1bd82000-11-13 22:57:25 +1100768 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
Damien Millereba71ba2000-04-29 23:57:08 +1000769 debug("Forcing server key to %d bits to make it differ from host key.",
770 options.server_key_bits);
771 }
772 }
773
Ben Lindstrom794325a2001-08-06 21:09:07 +0000774 /* Configuration looks good, so exit if in test mode. */
775 if (test_flag)
776 exit(0);
777
Damien Miller78315eb2000-09-29 23:01:36 +1100778#ifdef HAVE_SCO_PROTECTED_PW
779 (void) set_auth_parameters(ac, av);
780#endif
781
Damien Millereba71ba2000-04-29 23:57:08 +1000782 /* Initialize the log (it is reinitialized below in case we forked). */
Damien Miller95def091999-11-25 00:26:21 +1100783 if (debug_flag && !inetd_flag)
784 log_stderr = 1;
Kevin Stevesec84dc12000-12-13 17:45:15 +0000785 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +1100786
Damien Millereba71ba2000-04-29 23:57:08 +1000787 /*
788 * If not in debugging mode, and not started from inetd, disconnect
789 * from the controlling terminal, and fork. The original process
790 * exits.
791 */
Ben Lindstromc72745a2000-12-02 19:03:54 +0000792 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
Damien Miller95def091999-11-25 00:26:21 +1100793#ifdef TIOCNOTTY
794 int fd;
795#endif /* TIOCNOTTY */
796 if (daemon(0, 0) < 0)
797 fatal("daemon() failed: %.200s", strerror(errno));
798
799 /* Disconnect from the controlling tty. */
800#ifdef TIOCNOTTY
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000801 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
Damien Miller95def091999-11-25 00:26:21 +1100802 if (fd >= 0) {
803 (void) ioctl(fd, TIOCNOTTY, NULL);
804 close(fd);
805 }
806#endif /* TIOCNOTTY */
807 }
808 /* Reinitialize the log (because of the fork above). */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000809 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +1100810
Damien Miller95def091999-11-25 00:26:21 +1100811 /* Initialize the random number generator. */
812 arc4random_stir();
813
814 /* Chdir to the root directory so that the current disk can be
815 unmounted if desired. */
816 chdir("/");
Ben Lindstromde71cda2001-03-24 00:43:26 +0000817
818 /* ignore SIGPIPE */
819 signal(SIGPIPE, SIG_IGN);
Damien Miller95def091999-11-25 00:26:21 +1100820
Damien Miller95def091999-11-25 00:26:21 +1100821 /* Start listening for a socket, unless started from inetd. */
822 if (inetd_flag) {
Ben Lindstrom206941f2001-04-15 14:27:16 +0000823 int s1;
Damien Miller95def091999-11-25 00:26:21 +1100824 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
Ben Lindstrom206941f2001-04-15 14:27:16 +0000825 dup(s1);
Damien Miller95def091999-11-25 00:26:21 +1100826 sock_in = dup(0);
827 sock_out = dup(1);
Damien Miller994cf142000-07-21 10:19:44 +1000828 startup_pipe = -1;
Damien Millereba71ba2000-04-29 23:57:08 +1000829 /*
830 * We intentionally do not close the descriptors 0, 1, and 2
831 * as our code for setting the descriptors won\'t work if
832 * ttyfd happens to be one of those.
833 */
Damien Miller95def091999-11-25 00:26:21 +1100834 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100835 if (options.protocol & SSH_PROTO_1)
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000836 generate_ephemeral_server_key();
Damien Miller95def091999-11-25 00:26:21 +1100837 } else {
Damien Miller34132e52000-01-14 15:45:46 +1100838 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
839 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
840 continue;
841 if (num_listen_socks >= MAX_LISTEN_SOCKS)
842 fatal("Too many listen sockets. "
843 "Enlarge MAX_LISTEN_SOCKS");
844 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
845 ntop, sizeof(ntop), strport, sizeof(strport),
846 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
847 error("getnameinfo failed");
848 continue;
849 }
850 /* Create socket for listening. */
851 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
852 if (listen_sock < 0) {
853 /* kernel may not support ipv6 */
854 verbose("socket: %.100s", strerror(errno));
855 continue;
856 }
857 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
858 error("listen_sock O_NONBLOCK: %s", strerror(errno));
859 close(listen_sock);
860 continue;
861 }
862 /*
863 * Set socket options. We try to make the port
864 * reusable and have it close as fast as possible
865 * without waiting in unnecessary wait states on
866 * close.
867 */
868 setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
869 (void *) &on, sizeof(on));
870 linger.l_onoff = 1;
871 linger.l_linger = 5;
872 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
873 (void *) &linger, sizeof(linger));
Damien Miller95def091999-11-25 00:26:21 +1100874
Damien Miller34132e52000-01-14 15:45:46 +1100875 debug("Bind to port %s on %s.", strport, ntop);
Damien Miller95def091999-11-25 00:26:21 +1100876
Damien Miller34132e52000-01-14 15:45:46 +1100877 /* Bind the socket to the desired port. */
Damien Miller0a4e27d2001-02-18 12:36:39 +1100878 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
879 if (!ai->ai_next)
880 error("Bind to port %s on %s failed: %.200s.",
881 strport, ntop, strerror(errno));
Damien Miller34132e52000-01-14 15:45:46 +1100882 close(listen_sock);
883 continue;
884 }
885 listen_socks[num_listen_socks] = listen_sock;
886 num_listen_socks++;
Damien Miller95def091999-11-25 00:26:21 +1100887
Damien Miller34132e52000-01-14 15:45:46 +1100888 /* Start listening on the port. */
889 log("Server listening on %s port %s.", ntop, strport);
890 if (listen(listen_sock, 5) < 0)
891 fatal("listen: %.100s", strerror(errno));
892
Damien Miller95def091999-11-25 00:26:21 +1100893 }
Damien Miller34132e52000-01-14 15:45:46 +1100894 freeaddrinfo(options.listen_addrs);
895
896 if (!num_listen_socks)
897 fatal("Cannot bind any address.");
898
Ben Lindstrom98097862001-06-25 05:10:20 +0000899 if (options.protocol & SSH_PROTO_1)
900 generate_ephemeral_server_key();
901
902 /*
903 * Arrange to restart on SIGHUP. The handler needs
904 * listen_sock.
905 */
906 signal(SIGHUP, sighup_handler);
907
908 signal(SIGTERM, sigterm_handler);
909 signal(SIGQUIT, sigterm_handler);
910
911 /* Arrange SIGCHLD to be caught. */
912 signal(SIGCHLD, main_sigchld_handler);
913
914 /* Write out the pid file after the sigterm handler is setup */
Damien Miller95def091999-11-25 00:26:21 +1100915 if (!debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +1100916 /*
Ben Lindstrom7ad97102000-12-06 01:42:49 +0000917 * Record our pid in /var/run/sshd.pid to make it
918 * easier to kill the correct sshd. We don't want to
919 * do this before the bind above because the bind will
Damien Miller5428f641999-11-25 11:54:57 +1100920 * fail if there already is a daemon, and this will
921 * overwrite any old pid in the file.
922 */
Damien Millerbac2d8a2000-09-05 16:13:06 +1100923 f = fopen(options.pid_file, "wb");
Damien Miller95def091999-11-25 00:26:21 +1100924 if (f) {
Ben Lindstrom46c16222000-12-22 01:43:59 +0000925 fprintf(f, "%u\n", (u_int) getpid());
Damien Miller95def091999-11-25 00:26:21 +1100926 fclose(f);
927 }
928 }
Damien Miller95def091999-11-25 00:26:21 +1100929
Damien Miller34132e52000-01-14 15:45:46 +1100930 /* setup fd set for listen */
Damien Miller37023962000-07-11 17:31:38 +1000931 fdset = NULL;
Damien Miller34132e52000-01-14 15:45:46 +1100932 maxfd = 0;
933 for (i = 0; i < num_listen_socks; i++)
934 if (listen_socks[i] > maxfd)
935 maxfd = listen_socks[i];
Damien Miller37023962000-07-11 17:31:38 +1000936 /* pipes connected to unauthenticated childs */
937 startup_pipes = xmalloc(options.max_startups * sizeof(int));
938 for (i = 0; i < options.max_startups; i++)
939 startup_pipes[i] = -1;
Damien Miller34132e52000-01-14 15:45:46 +1100940
Damien Miller5428f641999-11-25 11:54:57 +1100941 /*
942 * Stay listening for connections until the system crashes or
943 * the daemon is killed with a signal.
944 */
Damien Miller95def091999-11-25 00:26:21 +1100945 for (;;) {
946 if (received_sighup)
947 sighup_restart();
Damien Miller37023962000-07-11 17:31:38 +1000948 if (fdset != NULL)
949 xfree(fdset);
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000950 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
Damien Miller37023962000-07-11 17:31:38 +1000951 fdset = (fd_set *)xmalloc(fdsetsz);
Damien Miller34132e52000-01-14 15:45:46 +1100952 memset(fdset, 0, fdsetsz);
Damien Miller37023962000-07-11 17:31:38 +1000953
Damien Miller34132e52000-01-14 15:45:46 +1100954 for (i = 0; i < num_listen_socks; i++)
955 FD_SET(listen_socks[i], fdset);
Damien Miller37023962000-07-11 17:31:38 +1000956 for (i = 0; i < options.max_startups; i++)
957 if (startup_pipes[i] != -1)
958 FD_SET(startup_pipes[i], fdset);
959
960 /* Wait in select until there is a connection. */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000961 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
962 if (ret < 0 && errno != EINTR)
963 error("select: %.100s", strerror(errno));
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000964 if (received_sigterm) {
965 log("Received signal %d; terminating.",
966 received_sigterm);
967 close_listen_socks();
968 unlink(options.pid_file);
969 exit(255);
970 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000971 if (key_used && key_do_regen) {
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000972 generate_ephemeral_server_key();
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000973 key_used = 0;
974 key_do_regen = 0;
Damien Miller34132e52000-01-14 15:45:46 +1100975 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000976 if (ret < 0)
977 continue;
978
Damien Miller37023962000-07-11 17:31:38 +1000979 for (i = 0; i < options.max_startups; i++)
980 if (startup_pipes[i] != -1 &&
981 FD_ISSET(startup_pipes[i], fdset)) {
982 /*
983 * the read end of the pipe is ready
984 * if the child has closed the pipe
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000985 * after successful authentication
Damien Miller37023962000-07-11 17:31:38 +1000986 * or if the child has died
987 */
988 close(startup_pipes[i]);
989 startup_pipes[i] = -1;
990 startups--;
991 }
Damien Miller34132e52000-01-14 15:45:46 +1100992 for (i = 0; i < num_listen_socks; i++) {
993 if (!FD_ISSET(listen_socks[i], fdset))
Damien Miller95def091999-11-25 00:26:21 +1100994 continue;
Damien Miller37023962000-07-11 17:31:38 +1000995 fromlen = sizeof(from);
996 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
997 &fromlen);
998 if (newsock < 0) {
999 if (errno != EINTR && errno != EWOULDBLOCK)
1000 error("accept: %.100s", strerror(errno));
1001 continue;
1002 }
1003 if (fcntl(newsock, F_SETFL, 0) < 0) {
1004 error("newsock del O_NONBLOCK: %s", strerror(errno));
1005 continue;
1006 }
Damien Miller942da032000-08-18 13:59:06 +10001007 if (drop_connection(startups) == 1) {
1008 debug("drop connection #%d", startups);
Damien Miller37023962000-07-11 17:31:38 +10001009 close(newsock);
1010 continue;
1011 }
1012 if (pipe(startup_p) == -1) {
1013 close(newsock);
1014 continue;
1015 }
1016
1017 for (j = 0; j < options.max_startups; j++)
1018 if (startup_pipes[j] == -1) {
1019 startup_pipes[j] = startup_p[0];
1020 if (maxfd < startup_p[0])
1021 maxfd = startup_p[0];
1022 startups++;
1023 break;
1024 }
Kevin Stevesef4eea92001-02-05 12:42:17 +00001025
Damien Miller5428f641999-11-25 11:54:57 +11001026 /*
Damien Miller37023962000-07-11 17:31:38 +10001027 * Got connection. Fork a child to handle it, unless
1028 * we are in debugging mode.
Damien Miller5428f641999-11-25 11:54:57 +11001029 */
Damien Miller37023962000-07-11 17:31:38 +10001030 if (debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +11001031 /*
Damien Miller37023962000-07-11 17:31:38 +10001032 * In debugging mode. Close the listening
1033 * socket, and start processing the
1034 * connection without forking.
Damien Miller5428f641999-11-25 11:54:57 +11001035 */
Damien Miller37023962000-07-11 17:31:38 +10001036 debug("Server will not fork when running in debugging mode.");
Damien Miller34132e52000-01-14 15:45:46 +11001037 close_listen_socks();
Damien Miller95def091999-11-25 00:26:21 +11001038 sock_in = newsock;
1039 sock_out = newsock;
Damien Miller4d97ba22000-07-11 18:15:50 +10001040 startup_pipe = -1;
Damien Miller182ee6e2000-07-12 09:45:27 +10001041 pid = getpid();
Damien Miller95def091999-11-25 00:26:21 +11001042 break;
Damien Miller37023962000-07-11 17:31:38 +10001043 } else {
1044 /*
1045 * Normal production daemon. Fork, and have
1046 * the child process the connection. The
1047 * parent continues listening.
1048 */
1049 if ((pid = fork()) == 0) {
1050 /*
1051 * Child. Close the listening and max_startup
1052 * sockets. Start using the accepted socket.
1053 * Reinitialize logging (since our pid has
1054 * changed). We break out of the loop to handle
1055 * the connection.
1056 */
1057 startup_pipe = startup_p[1];
1058 for (j = 0; j < options.max_startups; j++)
1059 if (startup_pipes[j] != -1)
1060 close(startup_pipes[j]);
1061 close_listen_socks();
1062 sock_in = newsock;
1063 sock_out = newsock;
Kevin Stevesec84dc12000-12-13 17:45:15 +00001064 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller37023962000-07-11 17:31:38 +10001065 break;
1066 }
Damien Miller95def091999-11-25 00:26:21 +11001067 }
Damien Miller37023962000-07-11 17:31:38 +10001068
1069 /* Parent. Stay in the loop. */
1070 if (pid < 0)
1071 error("fork: %.100s", strerror(errno));
1072 else
1073 debug("Forked child %d.", pid);
1074
1075 close(startup_p[1]);
1076
1077 /* Mark that the key has been used (it was "given" to the child). */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001078 if ((options.protocol & SSH_PROTO_1) &&
1079 key_used == 0) {
1080 /* Schedule server key regeneration alarm. */
1081 signal(SIGALRM, key_regeneration_alarm);
1082 alarm(options.key_regeneration_time);
1083 key_used = 1;
1084 }
Damien Miller37023962000-07-11 17:31:38 +10001085
1086 arc4random_stir();
1087
1088 /* Close the new socket (the child is now taking care of it). */
1089 close(newsock);
Damien Miller95def091999-11-25 00:26:21 +11001090 }
Damien Miller34132e52000-01-14 15:45:46 +11001091 /* child process check (or debug mode) */
1092 if (num_listen_socks < 0)
1093 break;
Damien Miller95def091999-11-25 00:26:21 +11001094 }
1095 }
1096
1097 /* This is the child processing a new connection. */
1098
Damien Miller5428f641999-11-25 11:54:57 +11001099 /*
1100 * Disable the key regeneration alarm. We will not regenerate the
1101 * key since we are no longer in a position to give it to anyone. We
1102 * will not restart on SIGHUP since it no longer makes sense.
1103 */
Damien Miller95def091999-11-25 00:26:21 +11001104 alarm(0);
1105 signal(SIGALRM, SIG_DFL);
1106 signal(SIGHUP, SIG_DFL);
1107 signal(SIGTERM, SIG_DFL);
1108 signal(SIGQUIT, SIG_DFL);
1109 signal(SIGCHLD, SIG_DFL);
Damien Miller4e0f5e12000-08-29 11:05:50 +11001110 signal(SIGINT, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +11001111
Damien Miller5428f641999-11-25 11:54:57 +11001112 /*
1113 * Set socket options for the connection. We want the socket to
1114 * close as fast as possible without waiting for anything. If the
1115 * connection is not a socket, these will do nothing.
1116 */
1117 /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
Damien Miller95def091999-11-25 00:26:21 +11001118 linger.l_onoff = 1;
1119 linger.l_linger = 5;
1120 setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1121
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001122 /* Set keepalives if requested. */
1123 if (options.keepalives &&
1124 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1125 sizeof(on)) < 0)
1126 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1127
Damien Miller5428f641999-11-25 11:54:57 +11001128 /*
1129 * Register our connection. This turns encryption off because we do
1130 * not have a key.
1131 */
Damien Miller95def091999-11-25 00:26:21 +11001132 packet_set_connection(sock_in, sock_out);
1133
1134 remote_port = get_remote_port();
1135 remote_ip = get_remote_ipaddr();
1136
1137 /* Check whether logins are denied from this host. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001138#ifdef LIBWRAP
Damien Miller34132e52000-01-14 15:45:46 +11001139 /* XXX LIBWRAP noes not know about IPv6 */
Damien Miller95def091999-11-25 00:26:21 +11001140 {
1141 struct request_info req;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001142
Ben Lindstromce89dac2001-09-12 16:58:04 +00001143 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
Damien Miller95def091999-11-25 00:26:21 +11001144 fromhost(&req);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001145
Damien Miller95def091999-11-25 00:26:21 +11001146 if (!hosts_access(&req)) {
Ben Lindstrom7de696e2001-03-29 00:45:12 +00001147 refuse(&req);
Damien Miller95def091999-11-25 00:26:21 +11001148 close(sock_in);
1149 close(sock_out);
Damien Miller95def091999-11-25 00:26:21 +11001150 }
Damien Miller34132e52000-01-14 15:45:46 +11001151/*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
Damien Miller95def091999-11-25 00:26:21 +11001152 }
Damien Miller34132e52000-01-14 15:45:46 +11001153#endif /* LIBWRAP */
Damien Miller95def091999-11-25 00:26:21 +11001154 /* Log the connection. */
1155 verbose("Connection from %.500s port %d", remote_ip, remote_port);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001156
Damien Miller5428f641999-11-25 11:54:57 +11001157 /*
1158 * We don\'t want to listen forever unless the other side
1159 * successfully authenticates itself. So we set up an alarm which is
1160 * cleared after successful authentication. A limit of zero
1161 * indicates no limit. Note that we don\'t set the alarm in debugging
1162 * mode; it is just annoying to have the server exit just when you
1163 * are about to discover the bug.
1164 */
Damien Miller95def091999-11-25 00:26:21 +11001165 signal(SIGALRM, grace_alarm_handler);
1166 if (!debug_flag)
1167 alarm(options.login_grace_time);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001168
Damien Millerb38eff82000-04-01 11:09:21 +10001169 sshd_exchange_identification(sock_in, sock_out);
Damien Miller5428f641999-11-25 11:54:57 +11001170 /*
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001171 * Check that the connection comes from a privileged port.
1172 * Rhosts-Authentication only makes sense from priviledged
Damien Miller5428f641999-11-25 11:54:57 +11001173 * programs. Of course, if the intruder has root access on his local
1174 * machine, he can connect from any port. So do not use these
1175 * authentication methods from machines that you do not trust.
1176 */
Damien Miller95def091999-11-25 00:26:21 +11001177 if (remote_port >= IPPORT_RESERVED ||
1178 remote_port < IPPORT_RESERVED / 2) {
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001179 debug("Rhosts Authentication disabled, "
Damien Miller0bc1bd82000-11-13 22:57:25 +11001180 "originating port not trusted.");
Damien Miller95def091999-11-25 00:26:21 +11001181 options.rhosts_authentication = 0;
Damien Miller95def091999-11-25 00:26:21 +11001182 }
Ben Lindstromec95ed92001-07-04 04:21:14 +00001183#if defined(KRB4) && !defined(KRB5)
Damien Miller34132e52000-01-14 15:45:46 +11001184 if (!packet_connection_is_ipv4() &&
1185 options.kerberos_authentication) {
1186 debug("Kerberos Authentication disabled, only available for IPv4.");
1187 options.kerberos_authentication = 0;
1188 }
Ben Lindstromec95ed92001-07-04 04:21:14 +00001189#endif /* KRB4 && !KRB5 */
Ben Lindstromf79aeff2001-02-10 21:27:11 +00001190#ifdef AFS
1191 /* If machine has AFS, set process authentication group. */
1192 if (k_hasafs()) {
1193 k_setpag();
1194 k_unlog();
1195 }
1196#endif /* AFS */
Damien Miller34132e52000-01-14 15:45:46 +11001197
Damien Miller95def091999-11-25 00:26:21 +11001198 packet_set_nonblocking();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001199
Damien Miller396691a2000-01-20 22:44:08 +11001200 /* perform the key exchange */
Damien Miller396691a2000-01-20 22:44:08 +11001201 /* authenticate user and start session */
Damien Millerefb4afe2000-04-12 18:45:05 +10001202 if (compat20) {
1203 do_ssh2_kex();
1204 do_authentication2();
1205 } else {
1206 do_ssh1_kex();
1207 do_authentication();
1208 }
Damien Miller95def091999-11-25 00:26:21 +11001209 /* The connection has been terminated. */
1210 verbose("Closing connection to %.100s", remote_ip);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001211
Damien Millerbeb4ba51999-12-28 15:09:35 +11001212#ifdef USE_PAM
Damien Millere72b7af1999-12-30 15:08:44 +11001213 finish_pam();
Damien Millerbeb4ba51999-12-28 15:09:35 +11001214#endif /* USE_PAM */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001215
Damien Miller95def091999-11-25 00:26:21 +11001216 packet_close();
1217 exit(0);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001218}
1219
Damien Miller95def091999-11-25 00:26:21 +11001220/*
Damien Miller396691a2000-01-20 22:44:08 +11001221 * SSH1 key exchange
Damien Miller95def091999-11-25 00:26:21 +11001222 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001223static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001224do_ssh1_kex(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001225{
Damien Miller95def091999-11-25 00:26:21 +11001226 int i, len;
Damien Miller396691a2000-01-20 22:44:08 +11001227 int plen, slen;
Damien Miller7650bc62001-01-30 09:27:26 +11001228 int rsafail = 0;
Damien Miller95def091999-11-25 00:26:21 +11001229 BIGNUM *session_key_int;
Ben Lindstrom46c16222000-12-22 01:43:59 +00001230 u_char session_key[SSH_SESSION_KEY_LENGTH];
1231 u_char cookie[8];
1232 u_int cipher_type, auth_mask, protocol_flags;
Damien Miller95def091999-11-25 00:26:21 +11001233 u_int32_t rand = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001234
Damien Miller5428f641999-11-25 11:54:57 +11001235 /*
1236 * Generate check bytes that the client must send back in the user
1237 * packet in order for it to be accepted; this is used to defy ip
1238 * spoofing attacks. Note that this only works against somebody
1239 * doing IP spoofing from a remote machine; any machine on the local
1240 * network can still see outgoing packets and catch the random
1241 * cookie. This only affects rhosts authentication, and this is one
1242 * of the reasons why it is inherently insecure.
1243 */
Damien Miller95def091999-11-25 00:26:21 +11001244 for (i = 0; i < 8; i++) {
1245 if (i % 4 == 0)
1246 rand = arc4random();
Damien Miller396691a2000-01-20 22:44:08 +11001247 cookie[i] = rand & 0xff;
Damien Miller95def091999-11-25 00:26:21 +11001248 rand >>= 8;
1249 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001250
Damien Miller5428f641999-11-25 11:54:57 +11001251 /*
1252 * Send our public key. We include in the packet 64 bits of random
1253 * data that must be matched in the reply in order to prevent IP
1254 * spoofing.
1255 */
Damien Miller95def091999-11-25 00:26:21 +11001256 packet_start(SSH_SMSG_PUBLIC_KEY);
1257 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001258 packet_put_char(cookie[i]);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001259
Damien Miller95def091999-11-25 00:26:21 +11001260 /* Store our public server RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001261 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1262 packet_put_bignum(sensitive_data.server_key->rsa->e);
1263 packet_put_bignum(sensitive_data.server_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001264
Damien Miller95def091999-11-25 00:26:21 +11001265 /* Store our public host RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001266 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1267 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1268 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001269
Damien Miller95def091999-11-25 00:26:21 +11001270 /* Put protocol flags. */
1271 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001272
Damien Miller95def091999-11-25 00:26:21 +11001273 /* Declare which ciphers we support. */
Damien Miller874d77b2000-10-14 16:23:11 +11001274 packet_put_int(cipher_mask_ssh1(0));
Damien Miller95def091999-11-25 00:26:21 +11001275
1276 /* Declare supported authentication types. */
1277 auth_mask = 0;
1278 if (options.rhosts_authentication)
1279 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1280 if (options.rhosts_rsa_authentication)
1281 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1282 if (options.rsa_authentication)
1283 auth_mask |= 1 << SSH_AUTH_RSA;
Ben Lindstromec95ed92001-07-04 04:21:14 +00001284#if defined(KRB4) || defined(KRB5)
Damien Miller95def091999-11-25 00:26:21 +11001285 if (options.kerberos_authentication)
1286 auth_mask |= 1 << SSH_AUTH_KERBEROS;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001287#endif
Ben Lindstromec95ed92001-07-04 04:21:14 +00001288#if defined(AFS) || defined(KRB5)
Damien Miller95def091999-11-25 00:26:21 +11001289 if (options.kerberos_tgt_passing)
1290 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
Ben Lindstromec95ed92001-07-04 04:21:14 +00001291#endif
1292#ifdef AFS
Damien Miller95def091999-11-25 00:26:21 +11001293 if (options.afs_token_passing)
1294 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001295#endif
Ben Lindstrom551ea372001-06-05 18:56:16 +00001296 if (options.challenge_response_authentication == 1)
Damien Miller95def091999-11-25 00:26:21 +11001297 auth_mask |= 1 << SSH_AUTH_TIS;
Damien Miller95def091999-11-25 00:26:21 +11001298 if (options.password_authentication)
1299 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1300 packet_put_int(auth_mask);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001301
Damien Miller95def091999-11-25 00:26:21 +11001302 /* Send the packet and wait for it to be sent. */
1303 packet_send();
1304 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001305
Damien Miller0bc1bd82000-11-13 22:57:25 +11001306 debug("Sent %d bit server key and %d bit host key.",
1307 BN_num_bits(sensitive_data.server_key->rsa->n),
1308 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001309
Damien Miller95def091999-11-25 00:26:21 +11001310 /* Read clients reply (cipher type and session key). */
1311 packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001312
Damien Miller50945fa1999-12-09 10:31:37 +11001313 /* Get cipher type and check whether we accept this. */
Damien Miller95def091999-11-25 00:26:21 +11001314 cipher_type = packet_get_char();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001315
Damien Miller874d77b2000-10-14 16:23:11 +11001316 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
Damien Miller50945fa1999-12-09 10:31:37 +11001317 packet_disconnect("Warning: client selects unsupported cipher.");
1318
Damien Miller95def091999-11-25 00:26:21 +11001319 /* Get check bytes from the packet. These must match those we
1320 sent earlier with the public key packet. */
1321 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001322 if (cookie[i] != packet_get_char())
Damien Miller95def091999-11-25 00:26:21 +11001323 packet_disconnect("IP Spoofing check bytes do not match.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001324
Damien Miller95def091999-11-25 00:26:21 +11001325 debug("Encryption type: %.200s", cipher_name(cipher_type));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001326
Damien Miller95def091999-11-25 00:26:21 +11001327 /* Get the encrypted integer. */
1328 session_key_int = BN_new();
1329 packet_get_bignum(session_key_int, &slen);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001330
Damien Miller95def091999-11-25 00:26:21 +11001331 protocol_flags = packet_get_int();
1332 packet_set_protocol_flags(protocol_flags);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001333
Damien Miller95def091999-11-25 00:26:21 +11001334 packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001335
Damien Miller5428f641999-11-25 11:54:57 +11001336 /*
1337 * Decrypt it using our private server key and private host key (key
1338 * with larger modulus first).
1339 */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001340 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
Damien Miller7650bc62001-01-30 09:27:26 +11001341 /* Server key has bigger modulus. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001342 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1343 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1344 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1345 get_remote_ipaddr(),
1346 BN_num_bits(sensitive_data.server_key->rsa->n),
1347 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1348 SSH_KEY_BITS_RESERVED);
Damien Miller95def091999-11-25 00:26:21 +11001349 }
Damien Miller7650bc62001-01-30 09:27:26 +11001350 if (rsa_private_decrypt(session_key_int, session_key_int,
1351 sensitive_data.server_key->rsa) <= 0)
1352 rsafail++;
1353 if (rsa_private_decrypt(session_key_int, session_key_int,
1354 sensitive_data.ssh1_host_key->rsa) <= 0)
1355 rsafail++;
Damien Miller95def091999-11-25 00:26:21 +11001356 } else {
1357 /* Host key has bigger modulus (or they are equal). */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001358 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1359 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1360 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1361 get_remote_ipaddr(),
1362 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1363 BN_num_bits(sensitive_data.server_key->rsa->n),
1364 SSH_KEY_BITS_RESERVED);
Damien Miller95def091999-11-25 00:26:21 +11001365 }
Damien Miller7650bc62001-01-30 09:27:26 +11001366 if (rsa_private_decrypt(session_key_int, session_key_int,
1367 sensitive_data.ssh1_host_key->rsa) < 0)
1368 rsafail++;
1369 if (rsa_private_decrypt(session_key_int, session_key_int,
1370 sensitive_data.server_key->rsa) < 0)
1371 rsafail++;
Damien Miller95def091999-11-25 00:26:21 +11001372 }
Damien Miller5428f641999-11-25 11:54:57 +11001373 /*
1374 * Extract session key from the decrypted integer. The key is in the
1375 * least significant 256 bits of the integer; the first byte of the
1376 * key is in the highest bits.
1377 */
Damien Miller7650bc62001-01-30 09:27:26 +11001378 if (!rsafail) {
1379 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1380 len = BN_num_bytes(session_key_int);
1381 if (len < 0 || len > sizeof(session_key)) {
1382 error("do_connection: bad session key len from %s: "
Ben Lindstrom31ca54a2001-02-09 02:11:24 +00001383 "session_key_int %d > sizeof(session_key) %lu",
1384 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
Damien Miller7650bc62001-01-30 09:27:26 +11001385 rsafail++;
1386 } else {
1387 memset(session_key, 0, sizeof(session_key));
1388 BN_bn2bin(session_key_int,
1389 session_key + sizeof(session_key) - len);
Ben Lindstromeb648a72001-03-05 06:00:29 +00001390
1391 compute_session_id(session_id, cookie,
1392 sensitive_data.ssh1_host_key->rsa->n,
1393 sensitive_data.server_key->rsa->n);
1394 /*
1395 * Xor the first 16 bytes of the session key with the
1396 * session id.
1397 */
1398 for (i = 0; i < 16; i++)
1399 session_key[i] ^= session_id[i];
Damien Miller7650bc62001-01-30 09:27:26 +11001400 }
1401 }
1402 if (rsafail) {
Ben Lindstromeb648a72001-03-05 06:00:29 +00001403 int bytes = BN_num_bytes(session_key_int);
1404 char *buf = xmalloc(bytes);
1405 MD5_CTX md;
1406
Damien Miller7650bc62001-01-30 09:27:26 +11001407 log("do_connection: generating a fake encryption key");
Ben Lindstromeb648a72001-03-05 06:00:29 +00001408 BN_bn2bin(session_key_int, buf);
1409 MD5_Init(&md);
1410 MD5_Update(&md, buf, bytes);
1411 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1412 MD5_Final(session_key, &md);
1413 MD5_Init(&md);
1414 MD5_Update(&md, session_key, 16);
1415 MD5_Update(&md, buf, bytes);
1416 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1417 MD5_Final(session_key + 16, &md);
1418 memset(buf, 0, bytes);
1419 xfree(buf);
Ben Lindstrom941ac822001-03-05 06:25:23 +00001420 for (i = 0; i < 16; i++)
1421 session_id[i] = session_key[i] ^ session_key[i + 16];
Damien Miller7650bc62001-01-30 09:27:26 +11001422 }
Ben Lindstromeb648a72001-03-05 06:00:29 +00001423 /* Destroy the private and public keys. They will no longer be needed. */
1424 destroy_sensitive_data();
1425
Damien Miller396691a2000-01-20 22:44:08 +11001426 /* Destroy the decrypted integer. It is no longer needed. */
1427 BN_clear_free(session_key_int);
1428
Damien Miller95def091999-11-25 00:26:21 +11001429 /* Set the session key. From this on all communications will be encrypted. */
1430 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001431
Damien Miller95def091999-11-25 00:26:21 +11001432 /* Destroy our copy of the session key. It is no longer needed. */
1433 memset(session_key, 0, sizeof(session_key));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001434
Damien Miller95def091999-11-25 00:26:21 +11001435 debug("Received session key; encryption turned on.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001436
Damien Miller95def091999-11-25 00:26:21 +11001437 /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1438 packet_start(SSH_SMSG_SUCCESS);
1439 packet_send();
1440 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001441}
Damien Millerefb4afe2000-04-12 18:45:05 +10001442
1443/*
1444 * SSH2 key exchange: diffie-hellman-group1-sha1
1445 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001446static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001447do_ssh2_kex(void)
Damien Millerefb4afe2000-04-12 18:45:05 +10001448{
Damien Millerefb4afe2000-04-12 18:45:05 +10001449 Kex *kex;
Damien Millerefb4afe2000-04-12 18:45:05 +10001450
Damien Miller78928792000-04-12 20:17:38 +10001451 if (options.ciphers != NULL) {
Damien Miller4af51302000-04-16 11:18:38 +10001452 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
Damien Miller78928792000-04-12 20:17:38 +10001453 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1454 }
Damien Millera0ff4662001-03-30 10:49:35 +10001455 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1456 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1457 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1458 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1459
Ben Lindstrom06b33aa2001-02-15 03:01:59 +00001460 if (options.macs != NULL) {
1461 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1462 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1463 }
Damien Miller0bc1bd82000-11-13 22:57:25 +11001464 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1465
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001466 /* start key exchange */
Ben Lindstrom238abf62001-04-04 17:52:53 +00001467 kex = kex_setup(myproposal);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001468 kex->server = 1;
1469 kex->client_version_string=client_version_string;
1470 kex->server_version_string=server_version_string;
1471 kex->load_host_key=&get_hostkey_by_type;
Damien Millerefb4afe2000-04-12 18:45:05 +10001472
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001473 xxx_kex = kex;
1474
Ben Lindstrombe2cc432001-04-04 23:46:07 +00001475 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
Damien Miller874d77b2000-10-14 16:23:11 +11001476
Ben Lindstrom2d90e002001-04-04 02:00:54 +00001477 session_id2 = kex->session_id;
1478 session_id2_len = kex->session_id_len;
1479
Damien Miller874d77b2000-10-14 16:23:11 +11001480#ifdef DEBUG_KEXDH
1481 /* send 1st encrypted/maced/compressed message */
1482 packet_start(SSH2_MSG_IGNORE);
1483 packet_put_cstring("markus");
1484 packet_send();
1485 packet_write_wait();
1486#endif
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001487 debug("KEX done");
Damien Millerefb4afe2000-04-12 18:45:05 +10001488}