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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:
Ben Lindstrom7a2073c2002-03-22 02:30:41 +000018 * Privilege Separation:
Damien Millere4340be2000-09-16 13:29:08 +110019 *
Ben Lindstrom7a2073c2002-03-22 02:30:41 +000020 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
21 * Copyright (c) 2002 Niels Provos. All rights reserved.
Damien Millere4340be2000-09-16 13:29:08 +110022 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
26 * 1. Redistributions of source code must retain the above copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 *
32 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
33 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
34 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
35 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
36 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
37 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
38 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
39 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
40 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
41 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Damien Miller95def091999-11-25 00:26:21 +110042 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100043
44#include "includes.h"
Ben Lindstromc2faa4a2002-11-09 15:50:03 +000045RCSID("$OpenBSD: sshd.c,v 1.261 2002/11/07 16:28:47 markus Exp $");
Damien Millerd4a8b7e1999-10-27 13:42:43 +100046
Ben Lindstrom226cfa02001-01-22 05:34:40 +000047#include <openssl/dh.h>
48#include <openssl/bn.h>
Damien Miller6a47f302002-02-13 13:55:06 +110049#include <openssl/md5.h>
Ben Lindstrom7a2073c2002-03-22 02:30:41 +000050#include <openssl/rand.h>
Kevin Steves0ea1d9d2002-04-25 18:17:04 +000051#ifdef HAVE_SECUREWARE
52#include <sys/security.h>
53#include <prot.h>
54#endif
Ben Lindstrom226cfa02001-01-22 05:34:40 +000055
56#include "ssh.h"
57#include "ssh1.h"
58#include "ssh2.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100059#include "xmalloc.h"
60#include "rsa.h"
Ben Lindstromd95c09c2001-02-18 19:13:33 +000061#include "sshpty.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100062#include "packet.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100063#include "mpaux.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000064#include "log.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100065#include "servconf.h"
66#include "uidswap.h"
67#include "compat.h"
Damien Millerb38eff82000-04-01 11:09:21 +100068#include "buffer.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000069#include "cipher.h"
Damien Millerefb4afe2000-04-12 18:45:05 +100070#include "kex.h"
Damien Millerb38eff82000-04-01 11:09:21 +100071#include "key.h"
Damien Miller874d77b2000-10-14 16:23:11 +110072#include "dh.h"
Damien Millerefb4afe2000-04-12 18:45:05 +100073#include "myproposal.h"
Damien Millereba71ba2000-04-29 23:57:08 +100074#include "authfile.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000075#include "pathnames.h"
76#include "atomicio.h"
77#include "canohost.h"
78#include "auth.h"
79#include "misc.h"
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +000080#include "dispatch.h"
Ben Lindstrom1bae4042001-10-03 17:46:39 +000081#include "channels.h"
Ben Lindstrom73ab9ba2002-03-22 01:27:35 +000082#include "session.h"
Ben Lindstrom7a2073c2002-03-22 02:30:41 +000083#include "monitor_mm.h"
84#include "monitor.h"
85#include "monitor_wrap.h"
86#include "monitor_fdpass.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100087
88#ifdef LIBWRAP
89#include <tcpd.h>
90#include <syslog.h>
91int allow_severity = LOG_INFO;
92int deny_severity = LOG_WARNING;
93#endif /* LIBWRAP */
94
95#ifndef O_NOCTTY
96#define O_NOCTTY 0
97#endif
98
Ben Lindstrom49a79c02000-11-17 03:47:20 +000099#ifdef HAVE___PROGNAME
100extern char *__progname;
101#else
102char *__progname;
103#endif
104
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000105/* Server configuration options. */
106ServerOptions options;
107
108/* Name of the server configuration file. */
Ben Lindstrom226cfa02001-01-22 05:34:40 +0000109char *config_file_name = _PATH_SERVER_CONFIG_FILE;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000110
Damien Miller4af51302000-04-16 11:18:38 +1000111/*
Damien Miller34132e52000-01-14 15:45:46 +1100112 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
113 * Default value is AF_UNSPEC means both IPv4 and IPv6.
114 */
Damien Miller7d80e342000-01-19 14:36:49 +1100115#ifdef IPV4_DEFAULT
116int IPv4or6 = AF_INET;
117#else
Damien Miller34132e52000-01-14 15:45:46 +1100118int IPv4or6 = AF_UNSPEC;
Damien Miller7d80e342000-01-19 14:36:49 +1100119#endif
Damien Miller34132e52000-01-14 15:45:46 +1100120
Damien Miller95def091999-11-25 00:26:21 +1100121/*
122 * Debug mode flag. This can be set on the command line. If debug
123 * mode is enabled, extra debugging output will be sent to the system
124 * log, the daemon will not go to background, and will exit after processing
125 * the first connection.
126 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000127int debug_flag = 0;
128
Ben Lindstrom794325a2001-08-06 21:09:07 +0000129/* Flag indicating that the daemon should only test the configuration and keys. */
130int test_flag = 0;
131
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000132/* Flag indicating that the daemon is being started from inetd. */
133int inetd_flag = 0;
134
Ben Lindstromc72745a2000-12-02 19:03:54 +0000135/* Flag indicating that sshd should not detach and become a daemon. */
136int no_daemon_flag = 0;
137
Damien Miller5ce662a1999-11-11 17:57:39 +1100138/* debug goes to stderr unless inetd_flag is set */
139int log_stderr = 0;
140
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000141/* Saved arguments to main(). */
142char **saved_argv;
Damien Millerb8c656e2000-06-28 15:22:41 +1000143int saved_argc;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000144
Damien Miller5428f641999-11-25 11:54:57 +1100145/*
Damien Miller34132e52000-01-14 15:45:46 +1100146 * The sockets that the server is listening; this is used in the SIGHUP
147 * signal handler.
Damien Miller5428f641999-11-25 11:54:57 +1100148 */
Damien Miller34132e52000-01-14 15:45:46 +1100149#define MAX_LISTEN_SOCKS 16
150int listen_socks[MAX_LISTEN_SOCKS];
151int num_listen_socks = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000152
Damien Miller5428f641999-11-25 11:54:57 +1100153/*
154 * the client's version string, passed by sshd2 in compat mode. if != NULL,
155 * sshd will skip the version-number exchange
156 */
Damien Miller95def091999-11-25 00:26:21 +1100157char *client_version_string = NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000158char *server_version_string = NULL;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000159
Ben Lindstrom8ac91062001-04-04 17:57:54 +0000160/* for rekeying XXX fixme */
161Kex *xxx_kex;
162
Damien Miller5428f641999-11-25 11:54:57 +1100163/*
164 * Any really sensitive data in the application is contained in this
165 * structure. The idea is that this structure could be locked into memory so
166 * that the pages do not get written into swap. However, there are some
167 * problems. The private key contains BIGNUMs, and we do not (in principle)
168 * have access to the internals of them, and locking just the structure is
169 * not very useful. Currently, memory locking is not implemented.
170 */
Damien Miller95def091999-11-25 00:26:21 +1100171struct {
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000172 Key *server_key; /* ephemeral server key */
Damien Miller0bc1bd82000-11-13 22:57:25 +1100173 Key *ssh1_host_key; /* ssh1 host key */
174 Key **host_keys; /* all private host keys */
175 int have_ssh1_key;
176 int have_ssh2_key;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000177 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000178} sensitive_data;
179
Damien Miller5428f641999-11-25 11:54:57 +1100180/*
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000181 * Flag indicating whether the RSA server key needs to be regenerated.
182 * Is set in the SIGALRM handler and cleared when the key is regenerated.
Damien Miller5428f641999-11-25 11:54:57 +1100183 */
Ben Lindstrom5e71c542001-12-06 16:48:14 +0000184static volatile sig_atomic_t key_do_regen = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000185
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000186/* This is set to true when a signal is received. */
Ben Lindstrom5e71c542001-12-06 16:48:14 +0000187static volatile sig_atomic_t received_sighup = 0;
188static volatile sig_atomic_t received_sigterm = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000189
Damien Millerb38eff82000-04-01 11:09:21 +1000190/* session identifier, used by RSA-auth */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000191u_char session_id[16];
Damien Millerb38eff82000-04-01 11:09:21 +1000192
Damien Millereba71ba2000-04-29 23:57:08 +1000193/* same for ssh2 */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000194u_char *session_id2 = NULL;
Damien Millereba71ba2000-04-29 23:57:08 +1000195int session_id2_len = 0;
196
Damien Miller942da032000-08-18 13:59:06 +1000197/* record remote hostname or ip */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000198u_int utmp_len = MAXHOSTNAMELEN;
Damien Miller942da032000-08-18 13:59:06 +1000199
Ben Lindstromd84df982001-12-06 16:35:40 +0000200/* options.max_startup sized array of fd ints */
201int *startup_pipes = NULL;
202int startup_pipe; /* in child */
203
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000204/* variables used for privilege separation */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000205extern struct monitor *pmonitor;
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000206extern int use_privsep;
207
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000208/* Prototypes for various functions defined later in this file. */
Ben Lindstrombba81212001-06-25 05:01:22 +0000209void destroy_sensitive_data(void);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000210void demote_sensitive_data(void);
Damien Miller98c7ad62000-03-09 21:27:49 +1100211
Ben Lindstrombba81212001-06-25 05:01:22 +0000212static void do_ssh1_kex(void);
213static void do_ssh2_kex(void);
Damien Miller874d77b2000-10-14 16:23:11 +1100214
Damien Miller98c7ad62000-03-09 21:27:49 +1100215/*
Damien Miller34132e52000-01-14 15:45:46 +1100216 * Close all listening sockets
217 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000218static void
Damien Miller34132e52000-01-14 15:45:46 +1100219close_listen_socks(void)
220{
221 int i;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000222
Damien Miller34132e52000-01-14 15:45:46 +1100223 for (i = 0; i < num_listen_socks; i++)
224 close(listen_socks[i]);
225 num_listen_socks = -1;
226}
227
Ben Lindstromd84df982001-12-06 16:35:40 +0000228static void
229close_startup_pipes(void)
230{
231 int i;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000232
Ben Lindstromd84df982001-12-06 16:35:40 +0000233 if (startup_pipes)
234 for (i = 0; i < options.max_startups; i++)
235 if (startup_pipes[i] != -1)
236 close(startup_pipes[i]);
237}
238
Damien Miller34132e52000-01-14 15:45:46 +1100239/*
Damien Miller95def091999-11-25 00:26:21 +1100240 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
241 * the effect is to reread the configuration file (and to regenerate
242 * the server key).
243 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000244static void
Damien Miller95def091999-11-25 00:26:21 +1100245sighup_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000246{
Ben Lindstrom07958482001-12-06 16:19:01 +0000247 int save_errno = errno;
248
Damien Miller95def091999-11-25 00:26:21 +1100249 received_sighup = 1;
250 signal(SIGHUP, sighup_handler);
Ben Lindstrom07958482001-12-06 16:19:01 +0000251 errno = save_errno;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000252}
253
Damien Miller95def091999-11-25 00:26:21 +1100254/*
255 * Called from the main program after receiving SIGHUP.
256 * Restarts the server.
257 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000258static void
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000259sighup_restart(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000260{
Damien Miller95def091999-11-25 00:26:21 +1100261 log("Received SIGHUP; restarting.");
Damien Miller34132e52000-01-14 15:45:46 +1100262 close_listen_socks();
Ben Lindstromd84df982001-12-06 16:35:40 +0000263 close_startup_pipes();
Damien Miller95def091999-11-25 00:26:21 +1100264 execv(saved_argv[0], saved_argv);
Ben Lindstrom822b6342002-06-23 21:38:49 +0000265 log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
266 strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100267 exit(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000268}
269
Damien Miller95def091999-11-25 00:26:21 +1100270/*
271 * Generic signal handler for terminating signals in the master daemon.
Damien Miller95def091999-11-25 00:26:21 +1100272 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000273static void
Damien Miller95def091999-11-25 00:26:21 +1100274sigterm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000275{
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000276 received_sigterm = sig;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000277}
278
Damien Miller95def091999-11-25 00:26:21 +1100279/*
280 * SIGCHLD handler. This is called whenever a child dies. This will then
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000281 * reap any zombies left by exited children.
Damien Miller95def091999-11-25 00:26:21 +1100282 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000283static void
Damien Miller95def091999-11-25 00:26:21 +1100284main_sigchld_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000285{
Damien Miller95def091999-11-25 00:26:21 +1100286 int save_errno = errno;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000287 pid_t pid;
Damien Miller95def091999-11-25 00:26:21 +1100288 int status;
Damien Miller431f66b1999-11-21 18:31:57 +1100289
Ben Lindstrom47fd8112002-04-02 20:48:19 +0000290 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
291 (pid < 0 && errno == EINTR))
Damien Miller95def091999-11-25 00:26:21 +1100292 ;
Damien Miller431f66b1999-11-21 18:31:57 +1100293
Damien Miller95def091999-11-25 00:26:21 +1100294 signal(SIGCHLD, main_sigchld_handler);
295 errno = save_errno;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000296}
297
Damien Miller95def091999-11-25 00:26:21 +1100298/*
299 * Signal handler for the alarm after the login grace period has expired.
300 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000301static void
Damien Miller95def091999-11-25 00:26:21 +1100302grace_alarm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000303{
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000304 /* XXX no idea how fix this signal handler */
305
Damien Miller95def091999-11-25 00:26:21 +1100306 /* Log error and exit. */
Damien Millerd27a76d2002-09-27 13:22:31 +1000307 fatal("Timeout before authentication for %s", get_remote_ipaddr());
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000308}
309
Damien Miller95def091999-11-25 00:26:21 +1100310/*
Damien Miller95def091999-11-25 00:26:21 +1100311 * Signal handler for the key regeneration alarm. Note that this
312 * alarm only occurs in the daemon waiting for connections, and it does not
313 * do anything with the private key or random state before forking.
314 * Thus there should be no concurrency control/asynchronous execution
315 * problems.
316 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000317static void
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000318generate_ephemeral_server_key(void)
Damien Miller0bc1bd82000-11-13 22:57:25 +1100319{
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +0000320 u_int32_t rnd = 0;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000321 int i;
322
Ben Lindstroma3700052001-04-05 23:26:32 +0000323 verbose("Generating %s%d bit RSA key.",
Damien Millerff75ac42001-03-30 10:50:32 +1000324 sensitive_data.server_key ? "new " : "", options.server_key_bits);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100325 if (sensitive_data.server_key != NULL)
326 key_free(sensitive_data.server_key);
Ben Lindstroma3700052001-04-05 23:26:32 +0000327 sensitive_data.server_key = key_generate(KEY_RSA1,
Damien Millerff75ac42001-03-30 10:50:32 +1000328 options.server_key_bits);
329 verbose("RSA key generation complete.");
Ben Lindstromeb648a72001-03-05 06:00:29 +0000330
331 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
332 if (i % 4 == 0)
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +0000333 rnd = arc4random();
334 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
335 rnd >>= 8;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000336 }
337 arc4random_stir();
Damien Miller0bc1bd82000-11-13 22:57:25 +1100338}
Ben Lindstrom2f959b42001-01-11 06:20:23 +0000339
Ben Lindstrombba81212001-06-25 05:01:22 +0000340static void
Damien Miller95def091999-11-25 00:26:21 +1100341key_regeneration_alarm(int sig)
342{
343 int save_errno = errno;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000344
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000345 signal(SIGALRM, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +1100346 errno = save_errno;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000347 key_do_regen = 1;
Damien Miller95def091999-11-25 00:26:21 +1100348}
349
Ben Lindstrombba81212001-06-25 05:01:22 +0000350static void
Damien Millerb38eff82000-04-01 11:09:21 +1000351sshd_exchange_identification(int sock_in, int sock_out)
352{
Damien Miller78928792000-04-12 20:17:38 +1000353 int i, mismatch;
Damien Millerb38eff82000-04-01 11:09:21 +1000354 int remote_major, remote_minor;
Damien Miller78928792000-04-12 20:17:38 +1000355 int major, minor;
Damien Millerb38eff82000-04-01 11:09:21 +1000356 char *s;
357 char buf[256]; /* Must not be larger than remote_version. */
358 char remote_version[256]; /* Must be at least as big as buf. */
359
Damien Miller78928792000-04-12 20:17:38 +1000360 if ((options.protocol & SSH_PROTO_1) &&
361 (options.protocol & SSH_PROTO_2)) {
362 major = PROTOCOL_MAJOR_1;
363 minor = 99;
364 } else if (options.protocol & SSH_PROTO_2) {
365 major = PROTOCOL_MAJOR_2;
366 minor = PROTOCOL_MINOR_2;
367 } else {
368 major = PROTOCOL_MAJOR_1;
369 minor = PROTOCOL_MINOR_1;
370 }
371 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
Damien Millerb38eff82000-04-01 11:09:21 +1000372 server_version_string = xstrdup(buf);
373
374 if (client_version_string == NULL) {
375 /* Send our protocol version identification. */
Ben Lindstrom5c385522002-06-23 21:23:20 +0000376 if (atomicio(write, sock_out, server_version_string,
377 strlen(server_version_string))
Damien Millerb38eff82000-04-01 11:09:21 +1000378 != strlen(server_version_string)) {
Damien Millere4a0ff42001-11-12 11:06:54 +1100379 log("Could not write ident string to %s", get_remote_ipaddr());
Damien Millerb38eff82000-04-01 11:09:21 +1000380 fatal_cleanup();
381 }
382
Ben Lindstromf666fec2002-06-06 19:51:58 +0000383 /* Read other sides version identification. */
Ben Lindstroma3700052001-04-05 23:26:32 +0000384 memset(buf, 0, sizeof(buf));
Damien Millerb38eff82000-04-01 11:09:21 +1000385 for (i = 0; i < sizeof(buf) - 1; i++) {
Damien Millerbf7f4662000-06-23 10:16:38 +1000386 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
Damien Millere4a0ff42001-11-12 11:06:54 +1100387 log("Did not receive identification string from %s",
Ben Lindstroma9a29e12001-02-20 01:20:47 +0000388 get_remote_ipaddr());
Damien Millerb38eff82000-04-01 11:09:21 +1000389 fatal_cleanup();
390 }
391 if (buf[i] == '\r') {
Ben Lindstrom69d8c072001-03-22 22:45:33 +0000392 buf[i] = 0;
Damien Miller874d77b2000-10-14 16:23:11 +1100393 /* Kludge for F-Secure Macintosh < 1.0.2 */
394 if (i == 12 &&
395 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
396 break;
Damien Millerb38eff82000-04-01 11:09:21 +1000397 continue;
Damien Millerb38eff82000-04-01 11:09:21 +1000398 }
399 if (buf[i] == '\n') {
Ben Lindstrom69d8c072001-03-22 22:45:33 +0000400 buf[i] = 0;
Damien Millerb38eff82000-04-01 11:09:21 +1000401 break;
402 }
403 }
404 buf[sizeof(buf) - 1] = 0;
405 client_version_string = xstrdup(buf);
406 }
407
408 /*
409 * Check that the versions match. In future this might accept
410 * several versions and set appropriate flags to handle them.
411 */
412 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
413 &remote_major, &remote_minor, remote_version) != 3) {
Damien Miller4af51302000-04-16 11:18:38 +1000414 s = "Protocol mismatch.\n";
Damien Millerb38eff82000-04-01 11:09:21 +1000415 (void) atomicio(write, sock_out, s, strlen(s));
416 close(sock_in);
417 close(sock_out);
418 log("Bad protocol version identification '%.100s' from %s",
419 client_version_string, get_remote_ipaddr());
420 fatal_cleanup();
421 }
422 debug("Client protocol version %d.%d; client software version %.100s",
Damien Miller9f0f5c62001-12-21 14:45:46 +1100423 remote_major, remote_minor, remote_version);
Damien Millerb38eff82000-04-01 11:09:21 +1000424
Damien Millerefb4afe2000-04-12 18:45:05 +1000425 compat_datafellows(remote_version);
426
Damien Millere9264972002-09-30 11:59:21 +1000427 if (datafellows & SSH_BUG_PROBE) {
428 log("probed from %s with %s. Don't panic.",
429 get_remote_ipaddr(), client_version_string);
430 fatal_cleanup();
431 }
432
Damien Miller27dbe6f2001-03-19 22:36:20 +1100433 if (datafellows & SSH_BUG_SCANNER) {
434 log("scanned from %s with %s. Don't panic.",
435 get_remote_ipaddr(), client_version_string);
436 fatal_cleanup();
437 }
438
Damien Miller78928792000-04-12 20:17:38 +1000439 mismatch = 0;
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000440 switch (remote_major) {
Damien Millerb38eff82000-04-01 11:09:21 +1000441 case 1:
Damien Millereba71ba2000-04-29 23:57:08 +1000442 if (remote_minor == 99) {
443 if (options.protocol & SSH_PROTO_2)
444 enable_compat20();
445 else
446 mismatch = 1;
447 break;
448 }
Damien Miller78928792000-04-12 20:17:38 +1000449 if (!(options.protocol & SSH_PROTO_1)) {
450 mismatch = 1;
451 break;
452 }
Damien Millerb38eff82000-04-01 11:09:21 +1000453 if (remote_minor < 3) {
Damien Miller37023962000-07-11 17:31:38 +1000454 packet_disconnect("Your ssh version is too old and "
Damien Millerb38eff82000-04-01 11:09:21 +1000455 "is no longer supported. Please install a newer version.");
456 } else if (remote_minor == 3) {
457 /* note that this disables agent-forwarding */
458 enable_compat13();
459 }
Damien Miller78928792000-04-12 20:17:38 +1000460 break;
Damien Millerefb4afe2000-04-12 18:45:05 +1000461 case 2:
Damien Miller78928792000-04-12 20:17:38 +1000462 if (options.protocol & SSH_PROTO_2) {
Damien Millerefb4afe2000-04-12 18:45:05 +1000463 enable_compat20();
464 break;
465 }
466 /* FALLTHROUGH */
Damien Miller4af51302000-04-16 11:18:38 +1000467 default:
Damien Miller78928792000-04-12 20:17:38 +1000468 mismatch = 1;
Damien Millerb38eff82000-04-01 11:09:21 +1000469 break;
470 }
Damien Millerefb4afe2000-04-12 18:45:05 +1000471 chop(server_version_string);
Damien Miller78928792000-04-12 20:17:38 +1000472 debug("Local version string %.200s", server_version_string);
473
474 if (mismatch) {
475 s = "Protocol major versions differ.\n";
476 (void) atomicio(write, sock_out, s, strlen(s));
477 close(sock_in);
478 close(sock_out);
479 log("Protocol major versions differ for %s: %.200s vs. %.200s",
480 get_remote_ipaddr(),
481 server_version_string, client_version_string);
482 fatal_cleanup();
483 }
Damien Millereba71ba2000-04-29 23:57:08 +1000484}
485
Damien Miller0bc1bd82000-11-13 22:57:25 +1100486/* Destroy the host and server keys. They will no longer be needed. */
Damien Millereba71ba2000-04-29 23:57:08 +1000487void
488destroy_sensitive_data(void)
489{
Damien Miller0bc1bd82000-11-13 22:57:25 +1100490 int i;
491
492 if (sensitive_data.server_key) {
493 key_free(sensitive_data.server_key);
494 sensitive_data.server_key = NULL;
495 }
Damien Miller9f0f5c62001-12-21 14:45:46 +1100496 for (i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100497 if (sensitive_data.host_keys[i]) {
498 key_free(sensitive_data.host_keys[i]);
499 sensitive_data.host_keys[i] = NULL;
500 }
501 }
502 sensitive_data.ssh1_host_key = NULL;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000503 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100504}
Damien Miller0bc1bd82000-11-13 22:57:25 +1100505
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000506/* Demote private to public keys for network child */
507void
508demote_sensitive_data(void)
509{
510 Key *tmp;
511 int i;
512
513 if (sensitive_data.server_key) {
514 tmp = key_demote(sensitive_data.server_key);
515 key_free(sensitive_data.server_key);
516 sensitive_data.server_key = tmp;
517 }
518
519 for (i = 0; i < options.num_host_key_files; i++) {
520 if (sensitive_data.host_keys[i]) {
521 tmp = key_demote(sensitive_data.host_keys[i]);
522 key_free(sensitive_data.host_keys[i]);
523 sensitive_data.host_keys[i] = tmp;
524 if (tmp->type == KEY_RSA1)
525 sensitive_data.ssh1_host_key = tmp;
526 }
527 }
528
529 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
530}
531
Ben Lindstrom08105192002-03-22 02:50:06 +0000532static void
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000533privsep_preauth_child(void)
534{
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +0000535 u_int32_t rnd[256];
Ben Lindstrom810af962002-07-04 00:11:40 +0000536 gid_t gidset[1];
Ben Lindstromc7431342002-03-22 03:11:49 +0000537 struct passwd *pw;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000538 int i;
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000539
540 /* Enable challenge-response authentication for privilege separation */
541 privsep_challenge_enable();
542
543 for (i = 0; i < 256; i++)
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +0000544 rnd[i] = arc4random();
545 RAND_seed(rnd, sizeof(rnd));
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000546
547 /* Demote the private keys to public keys. */
548 demote_sensitive_data();
549
Ben Lindstromc7431342002-03-22 03:11:49 +0000550 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
Damien Miller0150c652002-04-24 09:49:09 +1000551 fatal("Privilege separation user %s does not exist",
552 SSH_PRIVSEP_USER);
Ben Lindstromc7431342002-03-22 03:11:49 +0000553 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
554 endpwent();
555
Ben Lindstroma962c2f2002-07-04 00:14:17 +0000556 /* Change our root directory */
Ben Lindstrom7a7edf72002-03-22 02:42:37 +0000557 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
558 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
559 strerror(errno));
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000560 if (chdir("/") == -1)
Ben Lindstrom1ee9ec32002-03-22 03:14:45 +0000561 fatal("chdir(\"/\"): %s", strerror(errno));
Ben Lindstrom6328ab32002-03-22 02:54:23 +0000562
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000563 /* Drop our privileges */
Ben Lindstromc7431342002-03-22 03:11:49 +0000564 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
565 (u_int)pw->pw_gid);
Ben Lindstromfbcc3f72002-06-25 23:24:18 +0000566#if 0
567 /* XXX not ready, to heavy after chroot */
Ben Lindstromc7431342002-03-22 03:11:49 +0000568 do_setusercontext(pw);
Ben Lindstromfbcc3f72002-06-25 23:24:18 +0000569#else
570 gidset[0] = pw->pw_gid;
571 if (setgid(pw->pw_gid) < 0)
572 fatal("setgid failed for %u", pw->pw_gid );
573 if (setgroups(1, gidset) < 0)
574 fatal("setgroups: %.100s", strerror(errno));
575 permanently_set_uid(pw);
576#endif
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000577}
578
Ben Lindstroma962c2f2002-07-04 00:14:17 +0000579static Authctxt *
Ben Lindstrom943481c2002-03-22 03:43:46 +0000580privsep_preauth(void)
581{
582 Authctxt *authctxt = NULL;
583 int status;
584 pid_t pid;
585
586 /* Set up unprivileged child process to deal with network data */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000587 pmonitor = monitor_init();
Ben Lindstrom943481c2002-03-22 03:43:46 +0000588 /* Store a pointer to the kex for later rekeying */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000589 pmonitor->m_pkex = &xxx_kex;
Ben Lindstrom943481c2002-03-22 03:43:46 +0000590
591 pid = fork();
592 if (pid == -1) {
593 fatal("fork of unprivileged child failed");
594 } else if (pid != 0) {
Ben Lindstrom264ee302002-07-23 21:01:56 +0000595 fatal_remove_cleanup((void (*) (void *)) packet_close, NULL);
596
Ben Lindstromce0f6342002-06-11 16:42:49 +0000597 debug2("Network child is on pid %ld", (long)pid);
Ben Lindstrom943481c2002-03-22 03:43:46 +0000598
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000599 close(pmonitor->m_recvfd);
600 authctxt = monitor_child_preauth(pmonitor);
601 close(pmonitor->m_sendfd);
Ben Lindstrom943481c2002-03-22 03:43:46 +0000602
603 /* Sync memory */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000604 monitor_sync(pmonitor);
Ben Lindstrom943481c2002-03-22 03:43:46 +0000605
606 /* Wait for the child's exit status */
Ben Lindstrom47fd8112002-04-02 20:48:19 +0000607 while (waitpid(pid, &status, 0) < 0)
608 if (errno != EINTR)
609 break;
Ben Lindstrom264ee302002-07-23 21:01:56 +0000610
611 /* Reinstall, since the child has finished */
612 fatal_add_cleanup((void (*) (void *)) packet_close, NULL);
613
Ben Lindstrom943481c2002-03-22 03:43:46 +0000614 return (authctxt);
615 } else {
616 /* child */
617
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000618 close(pmonitor->m_sendfd);
Ben Lindstrom943481c2002-03-22 03:43:46 +0000619
620 /* Demote the child */
621 if (getuid() == 0 || geteuid() == 0)
622 privsep_preauth_child();
Ben Lindstromf90f58d2002-03-26 01:53:03 +0000623 setproctitle("%s", "[net]");
Ben Lindstrom943481c2002-03-22 03:43:46 +0000624 }
625 return (NULL);
626}
627
Ben Lindstrom08105192002-03-22 02:50:06 +0000628static void
Ben Lindstrom943481c2002-03-22 03:43:46 +0000629privsep_postauth(Authctxt *authctxt)
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000630{
631 extern Authctxt *x_authctxt;
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000632
633 /* XXX - Remote port forwarding */
634 x_authctxt = authctxt;
635
Tim Rice9dd30812002-07-07 13:43:36 -0700636#ifdef DISABLE_FD_PASSING
Tim Rice8eff3192002-06-25 15:35:15 -0700637 if (1) {
638#else
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000639 if (authctxt->pw->pw_uid == 0 || options.use_login) {
Tim Rice8eff3192002-06-25 15:35:15 -0700640#endif
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000641 /* File descriptor passing is broken or root login */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000642 monitor_apply_keystate(pmonitor);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000643 use_privsep = 0;
644 return;
645 }
Ben Lindstrom6328ab32002-03-22 02:54:23 +0000646
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000647 /* Authentication complete */
648 alarm(0);
649 if (startup_pipe != -1) {
650 close(startup_pipe);
651 startup_pipe = -1;
652 }
653
654 /* New socket pair */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000655 monitor_reinit(pmonitor);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000656
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000657 pmonitor->m_pid = fork();
658 if (pmonitor->m_pid == -1)
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000659 fatal("fork of unprivileged child failed");
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000660 else if (pmonitor->m_pid != 0) {
Ben Lindstrom264ee302002-07-23 21:01:56 +0000661 fatal_remove_cleanup((void (*) (void *)) packet_close, NULL);
662
Ben Lindstromce0f6342002-06-11 16:42:49 +0000663 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000664 close(pmonitor->m_recvfd);
665 monitor_child_postauth(pmonitor);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000666
667 /* NEVERREACHED */
668 exit(0);
669 }
670
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000671 close(pmonitor->m_sendfd);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000672
673 /* Demote the private keys to public keys. */
674 demote_sensitive_data();
675
676 /* Drop privileges */
677 do_setusercontext(authctxt->pw);
678
679 /* It is safe now to apply the key state */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000680 monitor_apply_keystate(pmonitor);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000681}
682
Ben Lindstrombba81212001-06-25 05:01:22 +0000683static char *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100684list_hostkey_types(void)
685{
Damien Miller0e3b8722002-01-22 23:26:38 +1100686 Buffer b;
687 char *p;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100688 int i;
Damien Miller0e3b8722002-01-22 23:26:38 +1100689
690 buffer_init(&b);
Damien Miller9f0f5c62001-12-21 14:45:46 +1100691 for (i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100692 Key *key = sensitive_data.host_keys[i];
693 if (key == NULL)
694 continue;
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000695 switch (key->type) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100696 case KEY_RSA:
697 case KEY_DSA:
Damien Miller0e3b8722002-01-22 23:26:38 +1100698 if (buffer_len(&b) > 0)
699 buffer_append(&b, ",", 1);
700 p = key_ssh_name(key);
701 buffer_append(&b, p, strlen(p));
Damien Miller0bc1bd82000-11-13 22:57:25 +1100702 break;
703 }
704 }
Damien Miller0e3b8722002-01-22 23:26:38 +1100705 buffer_append(&b, "\0", 1);
706 p = xstrdup(buffer_ptr(&b));
707 buffer_free(&b);
708 debug("list_hostkey_types: %s", p);
709 return p;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100710}
711
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000712Key *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100713get_hostkey_by_type(int type)
714{
715 int i;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000716
Damien Miller9f0f5c62001-12-21 14:45:46 +1100717 for (i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100718 Key *key = sensitive_data.host_keys[i];
719 if (key != NULL && key->type == type)
720 return key;
721 }
722 return NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000723}
724
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000725Key *
726get_hostkey_by_index(int ind)
727{
728 if (ind < 0 || ind >= options.num_host_key_files)
729 return (NULL);
730 return (sensitive_data.host_keys[ind]);
731}
732
733int
734get_hostkey_index(Key *key)
735{
736 int i;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000737
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000738 for (i = 0; i < options.num_host_key_files; i++) {
739 if (key == sensitive_data.host_keys[i])
740 return (i);
741 }
742 return (-1);
743}
744
Damien Miller942da032000-08-18 13:59:06 +1000745/*
746 * returns 1 if connection should be dropped, 0 otherwise.
747 * dropping starts at connection #max_startups_begin with a probability
748 * of (max_startups_rate/100). the probability increases linearly until
749 * all connections are dropped for startups > max_startups
750 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000751static int
Damien Miller942da032000-08-18 13:59:06 +1000752drop_connection(int startups)
753{
754 double p, r;
755
756 if (startups < options.max_startups_begin)
757 return 0;
758 if (startups >= options.max_startups)
759 return 1;
760 if (options.max_startups_rate == 100)
761 return 1;
762
763 p = 100 - options.max_startups_rate;
764 p *= startups - options.max_startups_begin;
765 p /= (double) (options.max_startups - options.max_startups_begin);
766 p += options.max_startups_rate;
767 p /= 100.0;
768 r = arc4random() / (double) UINT_MAX;
769
770 debug("drop_connection: p %g, r %g", p, r);
771 return (r < p) ? 1 : 0;
772}
773
Ben Lindstromade03f62001-12-06 18:22:17 +0000774static void
775usage(void)
776{
777 fprintf(stderr, "sshd version %s\n", SSH_VERSION);
778 fprintf(stderr, "Usage: %s [options]\n", __progname);
779 fprintf(stderr, "Options:\n");
780 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
781 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
782 fprintf(stderr, " -i Started from inetd\n");
783 fprintf(stderr, " -D Do not fork into daemon mode\n");
784 fprintf(stderr, " -t Only test configuration file and keys\n");
785 fprintf(stderr, " -q Quiet (no logging)\n");
786 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
787 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
788 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
789 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
790 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
791 _PATH_HOST_KEY_FILE);
792 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
793 fprintf(stderr, " -4 Use IPv4 only\n");
794 fprintf(stderr, " -6 Use IPv6 only\n");
795 fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n");
796 exit(1);
797}
798
Damien Miller95def091999-11-25 00:26:21 +1100799/*
800 * Main program for the daemon.
801 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000802int
803main(int ac, char **av)
804{
Damien Miller95def091999-11-25 00:26:21 +1100805 extern char *optarg;
806 extern int optind;
Damien Miller37023962000-07-11 17:31:38 +1000807 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
Damien Miller166fca82000-04-20 07:42:21 +1000808 pid_t pid;
Damien Miller34132e52000-01-14 15:45:46 +1100809 socklen_t fromlen;
Damien Miller34132e52000-01-14 15:45:46 +1100810 fd_set *fdset;
811 struct sockaddr_storage from;
Damien Miller95def091999-11-25 00:26:21 +1100812 const char *remote_ip;
813 int remote_port;
Damien Miller95def091999-11-25 00:26:21 +1100814 FILE *f;
Damien Miller34132e52000-01-14 15:45:46 +1100815 struct addrinfo *ai;
816 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
817 int listen_sock, maxfd;
Damien Miller37023962000-07-11 17:31:38 +1000818 int startup_p[2];
819 int startups = 0;
Ben Lindstrom73ab9ba2002-03-22 01:27:35 +0000820 Authctxt *authctxt;
Ben Lindstromd0fca422001-03-26 13:44:06 +0000821 Key *key;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000822 int ret, key_used = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000823
Kevin Steves0ea1d9d2002-04-25 18:17:04 +0000824#ifdef HAVE_SECUREWARE
825 (void)set_auth_parameters(ac, av);
826#endif
Ben Lindstrom49a79c02000-11-17 03:47:20 +0000827 __progname = get_progname(av[0]);
Damien Millerf9b625c2000-07-09 22:42:32 +1000828 init_rng();
829
Kevin Stevesec84dc12000-12-13 17:45:15 +0000830 /* Save argv. */
Damien Millerb8c656e2000-06-28 15:22:41 +1000831 saved_argc = ac;
Damien Miller95def091999-11-25 00:26:21 +1100832 saved_argv = av;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000833
Damien Miller95def091999-11-25 00:26:21 +1100834 /* Initialize configuration options to their default values. */
835 initialize_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000836
Damien Miller95def091999-11-25 00:26:21 +1100837 /* Parse command-line arguments. */
Ben Lindstromade03f62001-12-06 18:22:17 +0000838 while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) {
Damien Miller95def091999-11-25 00:26:21 +1100839 switch (opt) {
Damien Miller34132e52000-01-14 15:45:46 +1100840 case '4':
841 IPv4or6 = AF_INET;
842 break;
843 case '6':
844 IPv4or6 = AF_INET6;
845 break;
Damien Miller95def091999-11-25 00:26:21 +1100846 case 'f':
847 config_file_name = optarg;
848 break;
849 case 'd':
Damien Millere4340be2000-09-16 13:29:08 +1100850 if (0 == debug_flag) {
851 debug_flag = 1;
852 options.log_level = SYSLOG_LEVEL_DEBUG1;
853 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
854 options.log_level++;
855 } else {
856 fprintf(stderr, "Too high debugging level.\n");
857 exit(1);
858 }
Damien Miller95def091999-11-25 00:26:21 +1100859 break;
Ben Lindstromc72745a2000-12-02 19:03:54 +0000860 case 'D':
861 no_daemon_flag = 1;
862 break;
Ben Lindstrom9fce9f02001-04-11 23:10:09 +0000863 case 'e':
864 log_stderr = 1;
865 break;
Damien Miller95def091999-11-25 00:26:21 +1100866 case 'i':
867 inetd_flag = 1;
868 break;
869 case 'Q':
Ben Lindstromd5390202001-01-29 08:07:43 +0000870 /* ignored */
Damien Miller95def091999-11-25 00:26:21 +1100871 break;
872 case 'q':
873 options.log_level = SYSLOG_LEVEL_QUIET;
874 break;
875 case 'b':
876 options.server_key_bits = atoi(optarg);
877 break;
878 case 'p':
Damien Miller34132e52000-01-14 15:45:46 +1100879 options.ports_from_cmdline = 1;
Damien Millere4340be2000-09-16 13:29:08 +1100880 if (options.num_ports >= MAX_PORTS) {
881 fprintf(stderr, "too many ports.\n");
882 exit(1);
883 }
Ben Lindstrom19066a12001-04-12 23:39:26 +0000884 options.ports[options.num_ports++] = a2port(optarg);
885 if (options.ports[options.num_ports-1] == 0) {
886 fprintf(stderr, "Bad port number.\n");
887 exit(1);
888 }
Damien Miller95def091999-11-25 00:26:21 +1100889 break;
890 case 'g':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000891 if ((options.login_grace_time = convtime(optarg)) == -1) {
892 fprintf(stderr, "Invalid login grace time.\n");
893 exit(1);
894 }
Damien Miller95def091999-11-25 00:26:21 +1100895 break;
896 case 'k':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000897 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
898 fprintf(stderr, "Invalid key regeneration interval.\n");
899 exit(1);
900 }
Damien Miller95def091999-11-25 00:26:21 +1100901 break;
902 case 'h':
Damien Miller0bc1bd82000-11-13 22:57:25 +1100903 if (options.num_host_key_files >= MAX_HOSTKEYS) {
904 fprintf(stderr, "too many host keys.\n");
905 exit(1);
906 }
907 options.host_key_files[options.num_host_key_files++] = optarg;
Damien Miller95def091999-11-25 00:26:21 +1100908 break;
909 case 'V':
910 client_version_string = optarg;
911 /* only makes sense with inetd_flag, i.e. no listen() */
912 inetd_flag = 1;
913 break;
Ben Lindstrom794325a2001-08-06 21:09:07 +0000914 case 't':
915 test_flag = 1;
916 break;
Damien Miller942da032000-08-18 13:59:06 +1000917 case 'u':
918 utmp_len = atoi(optarg);
Ben Lindstrom41daec72002-07-23 21:15:13 +0000919 if (utmp_len > MAXHOSTNAMELEN) {
920 fprintf(stderr, "Invalid utmp length.\n");
921 exit(1);
922 }
Damien Miller942da032000-08-18 13:59:06 +1000923 break;
Ben Lindstromade03f62001-12-06 18:22:17 +0000924 case 'o':
Damien Miller9f0f5c62001-12-21 14:45:46 +1100925 if (process_server_config_line(&options, optarg,
Ben Lindstromade03f62001-12-06 18:22:17 +0000926 "command-line", 0) != 0)
Damien Miller9f0f5c62001-12-21 14:45:46 +1100927 exit(1);
Ben Lindstromade03f62001-12-06 18:22:17 +0000928 break;
Damien Miller95def091999-11-25 00:26:21 +1100929 case '?':
930 default:
Ben Lindstromade03f62001-12-06 18:22:17 +0000931 usage();
932 break;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000933 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000934 }
Ben Lindstrom425fb022001-03-29 00:31:20 +0000935 SSLeay_add_all_algorithms();
Ben Lindstrom908afed2001-10-03 17:34:59 +0000936 channel_set_af(IPv4or6);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000937
Damien Miller34132e52000-01-14 15:45:46 +1100938 /*
939 * Force logging to stderr until we have loaded the private host
940 * key (unless started from inetd)
941 */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000942 log_init(__progname,
Damien Miller5aa5d782002-02-08 22:01:54 +1100943 options.log_level == SYSLOG_LEVEL_NOT_SET ?
944 SYSLOG_LEVEL_INFO : options.log_level,
945 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
946 SYSLOG_FACILITY_AUTH : options.log_facility,
Ben Lindstromc2faa4a2002-11-09 15:50:03 +0000947 log_stderr || !inetd_flag);
Damien Miller34132e52000-01-14 15:45:46 +1100948
Tim Rice81ed5182002-09-25 17:38:46 -0700949#ifdef _UNICOS
Ben Lindstrom6db66ff2001-08-06 23:29:16 +0000950 /* Cray can define user privs drop all prives now!
951 * Not needed on PRIV_SU systems!
952 */
953 drop_cray_privs();
954#endif
955
Damien Miller60bc5172001-03-19 09:38:15 +1100956 seed_rng();
957
Damien Miller95def091999-11-25 00:26:21 +1100958 /* Read server configuration options from the configuration file. */
959 read_server_config(&options, config_file_name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000960
Damien Miller95def091999-11-25 00:26:21 +1100961 /* Fill in default values for those options not explicitly set. */
962 fill_default_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000963
Damien Miller95def091999-11-25 00:26:21 +1100964 /* Check that there are no remaining arguments. */
965 if (optind < ac) {
966 fprintf(stderr, "Extra argument %s.\n", av[optind]);
967 exit(1);
968 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000969
Damien Miller95def091999-11-25 00:26:21 +1100970 debug("sshd version %.100s", SSH_VERSION);
Damien Miller2ccf6611999-11-15 15:25:10 +1100971
Damien Miller0bc1bd82000-11-13 22:57:25 +1100972 /* load private host keys */
Ben Lindstroma962c2f2002-07-04 00:14:17 +0000973 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
974 sizeof(Key *));
Damien Miller9f0f5c62001-12-21 14:45:46 +1100975 for (i = 0; i < options.num_host_key_files; i++)
Ben Lindstrom46c16222000-12-22 01:43:59 +0000976 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100977 sensitive_data.server_key = NULL;
978 sensitive_data.ssh1_host_key = NULL;
979 sensitive_data.have_ssh1_key = 0;
980 sensitive_data.have_ssh2_key = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000981
Damien Miller9f0f5c62001-12-21 14:45:46 +1100982 for (i = 0; i < options.num_host_key_files; i++) {
Ben Lindstromd0fca422001-03-26 13:44:06 +0000983 key = key_load_private(options.host_key_files[i], "", NULL);
984 sensitive_data.host_keys[i] = key;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100985 if (key == NULL) {
Ben Lindstrom15f33862001-04-16 02:00:02 +0000986 error("Could not load host key: %s",
987 options.host_key_files[i]);
Ben Lindstromd0fca422001-03-26 13:44:06 +0000988 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100989 continue;
990 }
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000991 switch (key->type) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100992 case KEY_RSA1:
993 sensitive_data.ssh1_host_key = key;
994 sensitive_data.have_ssh1_key = 1;
995 break;
996 case KEY_RSA:
997 case KEY_DSA:
998 sensitive_data.have_ssh2_key = 1;
999 break;
1000 }
Ben Lindstromd0fca422001-03-26 13:44:06 +00001001 debug("private host key: #%d type %d %s", i, key->type,
1002 key_type(key));
Damien Miller0bc1bd82000-11-13 22:57:25 +11001003 }
1004 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1005 log("Disabling protocol version 1. Could not load host key");
Damien Millereba71ba2000-04-29 23:57:08 +10001006 options.protocol &= ~SSH_PROTO_1;
1007 }
Damien Miller0bc1bd82000-11-13 22:57:25 +11001008 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1009 log("Disabling protocol version 2. Could not load host key");
1010 options.protocol &= ~SSH_PROTO_2;
Damien Millereba71ba2000-04-29 23:57:08 +10001011 }
Kevin Stevesadf74cd2001-02-05 14:22:50 +00001012 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
Ben Lindstrom6df8ef42001-03-05 07:47:23 +00001013 log("sshd: no hostkeys available -- exiting.");
Damien Miller95def091999-11-25 00:26:21 +11001014 exit(1);
1015 }
Damien Miller95def091999-11-25 00:26:21 +11001016
Damien Millereba71ba2000-04-29 23:57:08 +10001017 /* Check certain values for sanity. */
1018 if (options.protocol & SSH_PROTO_1) {
1019 if (options.server_key_bits < 512 ||
1020 options.server_key_bits > 32768) {
1021 fprintf(stderr, "Bad server key size.\n");
1022 exit(1);
1023 }
1024 /*
1025 * Check that server and host key lengths differ sufficiently. This
1026 * is necessary to make double encryption work with rsaref. Oh, I
1027 * hate software patents. I dont know if this can go? Niels
1028 */
1029 if (options.server_key_bits >
Ben Lindstrom822b6342002-06-23 21:38:49 +00001030 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1031 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1032 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1033 SSH_KEY_BITS_RESERVED) {
Damien Millereba71ba2000-04-29 23:57:08 +10001034 options.server_key_bits =
Ben Lindstrom822b6342002-06-23 21:38:49 +00001035 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1036 SSH_KEY_BITS_RESERVED;
Damien Millereba71ba2000-04-29 23:57:08 +10001037 debug("Forcing server key to %d bits to make it differ from host key.",
1038 options.server_key_bits);
1039 }
1040 }
1041
Ben Lindstroma26ea632002-06-06 20:46:25 +00001042 if (use_privsep) {
1043 struct passwd *pw;
1044 struct stat st;
1045
1046 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1047 fatal("Privilege separation user %s does not exist",
1048 SSH_PRIVSEP_USER);
1049 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1050 (S_ISDIR(st.st_mode) == 0))
1051 fatal("Missing privilege separation directory: %s",
1052 _PATH_PRIVSEP_CHROOT_DIR);
Ben Lindstrom59627352002-06-27 18:02:21 +00001053
1054#ifdef HAVE_CYGWIN
1055 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1056 (st.st_uid != getuid () ||
1057 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1058#else
Ben Lindstrom2dfacb32002-06-23 00:33:47 +00001059 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
Ben Lindstrom59627352002-06-27 18:02:21 +00001060#endif
Ben Lindstrom2dfacb32002-06-23 00:33:47 +00001061 fatal("Bad owner or mode for %s",
1062 _PATH_PRIVSEP_CHROOT_DIR);
Ben Lindstroma26ea632002-06-06 20:46:25 +00001063 }
1064
Ben Lindstrom794325a2001-08-06 21:09:07 +00001065 /* Configuration looks good, so exit if in test mode. */
1066 if (test_flag)
1067 exit(0);
1068
Damien Miller87aea252002-05-10 12:20:24 +10001069 /*
1070 * Clear out any supplemental groups we may have inherited. This
1071 * prevents inadvertent creation of files with bad modes (in the
1072 * portable version at least, it's certainly possible for PAM
1073 * to create a file, and we can't control the code in every
1074 * module which might be used).
1075 */
1076 if (setgroups(0, NULL) < 0)
1077 debug("setgroups() failed: %.200s", strerror(errno));
1078
Damien Millereba71ba2000-04-29 23:57:08 +10001079 /* Initialize the log (it is reinitialized below in case we forked). */
Damien Miller95def091999-11-25 00:26:21 +11001080 if (debug_flag && !inetd_flag)
1081 log_stderr = 1;
Kevin Stevesec84dc12000-12-13 17:45:15 +00001082 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +11001083
Damien Millereba71ba2000-04-29 23:57:08 +10001084 /*
1085 * If not in debugging mode, and not started from inetd, disconnect
1086 * from the controlling terminal, and fork. The original process
1087 * exits.
1088 */
Ben Lindstromc72745a2000-12-02 19:03:54 +00001089 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
Damien Miller95def091999-11-25 00:26:21 +11001090#ifdef TIOCNOTTY
1091 int fd;
1092#endif /* TIOCNOTTY */
1093 if (daemon(0, 0) < 0)
1094 fatal("daemon() failed: %.200s", strerror(errno));
1095
1096 /* Disconnect from the controlling tty. */
1097#ifdef TIOCNOTTY
Ben Lindstrom31ca54a2001-02-09 02:11:24 +00001098 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
Damien Miller95def091999-11-25 00:26:21 +11001099 if (fd >= 0) {
1100 (void) ioctl(fd, TIOCNOTTY, NULL);
1101 close(fd);
1102 }
1103#endif /* TIOCNOTTY */
1104 }
1105 /* Reinitialize the log (because of the fork above). */
Kevin Stevesec84dc12000-12-13 17:45:15 +00001106 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +11001107
Damien Miller95def091999-11-25 00:26:21 +11001108 /* Initialize the random number generator. */
1109 arc4random_stir();
1110
1111 /* Chdir to the root directory so that the current disk can be
1112 unmounted if desired. */
1113 chdir("/");
Damien Miller9f0f5c62001-12-21 14:45:46 +11001114
Ben Lindstromde71cda2001-03-24 00:43:26 +00001115 /* ignore SIGPIPE */
1116 signal(SIGPIPE, SIG_IGN);
Damien Miller95def091999-11-25 00:26:21 +11001117
Damien Miller95def091999-11-25 00:26:21 +11001118 /* Start listening for a socket, unless started from inetd. */
1119 if (inetd_flag) {
Ben Lindstrom206941f2001-04-15 14:27:16 +00001120 int s1;
Damien Miller95def091999-11-25 00:26:21 +11001121 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
Ben Lindstrom206941f2001-04-15 14:27:16 +00001122 dup(s1);
Damien Miller95def091999-11-25 00:26:21 +11001123 sock_in = dup(0);
1124 sock_out = dup(1);
Damien Miller994cf142000-07-21 10:19:44 +10001125 startup_pipe = -1;
Damien Millereba71ba2000-04-29 23:57:08 +10001126 /*
1127 * We intentionally do not close the descriptors 0, 1, and 2
1128 * as our code for setting the descriptors won\'t work if
1129 * ttyfd happens to be one of those.
1130 */
Damien Miller95def091999-11-25 00:26:21 +11001131 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
Damien Miller0bc1bd82000-11-13 22:57:25 +11001132 if (options.protocol & SSH_PROTO_1)
Ben Lindstromca42d5f2001-03-09 18:25:32 +00001133 generate_ephemeral_server_key();
Damien Miller95def091999-11-25 00:26:21 +11001134 } else {
Damien Miller34132e52000-01-14 15:45:46 +11001135 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1136 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1137 continue;
1138 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1139 fatal("Too many listen sockets. "
1140 "Enlarge MAX_LISTEN_SOCKS");
1141 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1142 ntop, sizeof(ntop), strport, sizeof(strport),
1143 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1144 error("getnameinfo failed");
1145 continue;
1146 }
1147 /* Create socket for listening. */
1148 listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
1149 if (listen_sock < 0) {
1150 /* kernel may not support ipv6 */
1151 verbose("socket: %.100s", strerror(errno));
1152 continue;
1153 }
1154 if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
1155 error("listen_sock O_NONBLOCK: %s", strerror(errno));
1156 close(listen_sock);
1157 continue;
1158 }
1159 /*
Damien Millere1383ce2002-09-19 11:49:37 +10001160 * Set socket options.
1161 * Allow local port reuse in TIME_WAIT.
Damien Miller34132e52000-01-14 15:45:46 +11001162 */
Damien Millere1383ce2002-09-19 11:49:37 +10001163 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1164 &on, sizeof(on)) == -1)
1165 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +11001166
Damien Miller34132e52000-01-14 15:45:46 +11001167 debug("Bind to port %s on %s.", strport, ntop);
Damien Miller95def091999-11-25 00:26:21 +11001168
Damien Miller34132e52000-01-14 15:45:46 +11001169 /* Bind the socket to the desired port. */
Damien Miller0a4e27d2001-02-18 12:36:39 +11001170 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1171 if (!ai->ai_next)
1172 error("Bind to port %s on %s failed: %.200s.",
1173 strport, ntop, strerror(errno));
Damien Miller34132e52000-01-14 15:45:46 +11001174 close(listen_sock);
1175 continue;
1176 }
1177 listen_socks[num_listen_socks] = listen_sock;
1178 num_listen_socks++;
Damien Miller95def091999-11-25 00:26:21 +11001179
Damien Miller34132e52000-01-14 15:45:46 +11001180 /* Start listening on the port. */
1181 log("Server listening on %s port %s.", ntop, strport);
1182 if (listen(listen_sock, 5) < 0)
1183 fatal("listen: %.100s", strerror(errno));
1184
Damien Miller95def091999-11-25 00:26:21 +11001185 }
Damien Miller34132e52000-01-14 15:45:46 +11001186 freeaddrinfo(options.listen_addrs);
1187
1188 if (!num_listen_socks)
1189 fatal("Cannot bind any address.");
1190
Ben Lindstrom98097862001-06-25 05:10:20 +00001191 if (options.protocol & SSH_PROTO_1)
1192 generate_ephemeral_server_key();
1193
1194 /*
1195 * Arrange to restart on SIGHUP. The handler needs
1196 * listen_sock.
1197 */
1198 signal(SIGHUP, sighup_handler);
1199
1200 signal(SIGTERM, sigterm_handler);
1201 signal(SIGQUIT, sigterm_handler);
1202
1203 /* Arrange SIGCHLD to be caught. */
1204 signal(SIGCHLD, main_sigchld_handler);
1205
1206 /* Write out the pid file after the sigterm handler is setup */
Damien Miller95def091999-11-25 00:26:21 +11001207 if (!debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +11001208 /*
Ben Lindstrom7ad97102000-12-06 01:42:49 +00001209 * Record our pid in /var/run/sshd.pid to make it
1210 * easier to kill the correct sshd. We don't want to
1211 * do this before the bind above because the bind will
Damien Miller5428f641999-11-25 11:54:57 +11001212 * fail if there already is a daemon, and this will
1213 * overwrite any old pid in the file.
1214 */
Damien Millerbac2d8a2000-09-05 16:13:06 +11001215 f = fopen(options.pid_file, "wb");
Damien Miller95def091999-11-25 00:26:21 +11001216 if (f) {
Ben Lindstromce0f6342002-06-11 16:42:49 +00001217 fprintf(f, "%ld\n", (long) getpid());
Damien Miller95def091999-11-25 00:26:21 +11001218 fclose(f);
1219 }
1220 }
Damien Miller95def091999-11-25 00:26:21 +11001221
Damien Miller34132e52000-01-14 15:45:46 +11001222 /* setup fd set for listen */
Damien Miller37023962000-07-11 17:31:38 +10001223 fdset = NULL;
Damien Miller34132e52000-01-14 15:45:46 +11001224 maxfd = 0;
1225 for (i = 0; i < num_listen_socks; i++)
1226 if (listen_socks[i] > maxfd)
1227 maxfd = listen_socks[i];
Damien Miller37023962000-07-11 17:31:38 +10001228 /* pipes connected to unauthenticated childs */
1229 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1230 for (i = 0; i < options.max_startups; i++)
1231 startup_pipes[i] = -1;
Damien Miller34132e52000-01-14 15:45:46 +11001232
Damien Miller5428f641999-11-25 11:54:57 +11001233 /*
1234 * Stay listening for connections until the system crashes or
1235 * the daemon is killed with a signal.
1236 */
Damien Miller95def091999-11-25 00:26:21 +11001237 for (;;) {
1238 if (received_sighup)
1239 sighup_restart();
Damien Miller37023962000-07-11 17:31:38 +10001240 if (fdset != NULL)
1241 xfree(fdset);
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001242 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
Damien Miller37023962000-07-11 17:31:38 +10001243 fdset = (fd_set *)xmalloc(fdsetsz);
Damien Miller34132e52000-01-14 15:45:46 +11001244 memset(fdset, 0, fdsetsz);
Damien Miller37023962000-07-11 17:31:38 +10001245
Damien Miller34132e52000-01-14 15:45:46 +11001246 for (i = 0; i < num_listen_socks; i++)
1247 FD_SET(listen_socks[i], fdset);
Damien Miller37023962000-07-11 17:31:38 +10001248 for (i = 0; i < options.max_startups; i++)
1249 if (startup_pipes[i] != -1)
1250 FD_SET(startup_pipes[i], fdset);
1251
1252 /* Wait in select until there is a connection. */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001253 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1254 if (ret < 0 && errno != EINTR)
1255 error("select: %.100s", strerror(errno));
Ben Lindstromec46e0b2001-06-09 01:27:31 +00001256 if (received_sigterm) {
1257 log("Received signal %d; terminating.",
Ben Lindstromf8f065b2001-12-06 17:52:16 +00001258 (int) received_sigterm);
Ben Lindstromec46e0b2001-06-09 01:27:31 +00001259 close_listen_socks();
1260 unlink(options.pid_file);
1261 exit(255);
1262 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001263 if (key_used && key_do_regen) {
Ben Lindstromca42d5f2001-03-09 18:25:32 +00001264 generate_ephemeral_server_key();
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001265 key_used = 0;
1266 key_do_regen = 0;
Damien Miller34132e52000-01-14 15:45:46 +11001267 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001268 if (ret < 0)
1269 continue;
1270
Damien Miller37023962000-07-11 17:31:38 +10001271 for (i = 0; i < options.max_startups; i++)
1272 if (startup_pipes[i] != -1 &&
1273 FD_ISSET(startup_pipes[i], fdset)) {
1274 /*
1275 * the read end of the pipe is ready
1276 * if the child has closed the pipe
Ben Lindstrom4dccfa52000-12-28 16:40:05 +00001277 * after successful authentication
Damien Miller37023962000-07-11 17:31:38 +10001278 * or if the child has died
1279 */
1280 close(startup_pipes[i]);
1281 startup_pipes[i] = -1;
1282 startups--;
1283 }
Damien Miller34132e52000-01-14 15:45:46 +11001284 for (i = 0; i < num_listen_socks; i++) {
1285 if (!FD_ISSET(listen_socks[i], fdset))
Damien Miller95def091999-11-25 00:26:21 +11001286 continue;
Damien Miller37023962000-07-11 17:31:38 +10001287 fromlen = sizeof(from);
1288 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1289 &fromlen);
1290 if (newsock < 0) {
1291 if (errno != EINTR && errno != EWOULDBLOCK)
1292 error("accept: %.100s", strerror(errno));
1293 continue;
1294 }
1295 if (fcntl(newsock, F_SETFL, 0) < 0) {
1296 error("newsock del O_NONBLOCK: %s", strerror(errno));
Damien Miller72c336d2001-12-21 12:44:28 +11001297 close(newsock);
Damien Miller37023962000-07-11 17:31:38 +10001298 continue;
1299 }
Damien Miller942da032000-08-18 13:59:06 +10001300 if (drop_connection(startups) == 1) {
1301 debug("drop connection #%d", startups);
Damien Miller37023962000-07-11 17:31:38 +10001302 close(newsock);
1303 continue;
1304 }
1305 if (pipe(startup_p) == -1) {
1306 close(newsock);
1307 continue;
1308 }
1309
1310 for (j = 0; j < options.max_startups; j++)
1311 if (startup_pipes[j] == -1) {
1312 startup_pipes[j] = startup_p[0];
1313 if (maxfd < startup_p[0])
1314 maxfd = startup_p[0];
1315 startups++;
1316 break;
1317 }
Kevin Stevesef4eea92001-02-05 12:42:17 +00001318
Damien Miller5428f641999-11-25 11:54:57 +11001319 /*
Damien Miller37023962000-07-11 17:31:38 +10001320 * Got connection. Fork a child to handle it, unless
1321 * we are in debugging mode.
Damien Miller5428f641999-11-25 11:54:57 +11001322 */
Damien Miller37023962000-07-11 17:31:38 +10001323 if (debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +11001324 /*
Damien Miller37023962000-07-11 17:31:38 +10001325 * In debugging mode. Close the listening
1326 * socket, and start processing the
1327 * connection without forking.
Damien Miller5428f641999-11-25 11:54:57 +11001328 */
Damien Miller37023962000-07-11 17:31:38 +10001329 debug("Server will not fork when running in debugging mode.");
Damien Miller34132e52000-01-14 15:45:46 +11001330 close_listen_socks();
Damien Miller95def091999-11-25 00:26:21 +11001331 sock_in = newsock;
1332 sock_out = newsock;
Damien Miller4d97ba22000-07-11 18:15:50 +10001333 startup_pipe = -1;
Damien Miller182ee6e2000-07-12 09:45:27 +10001334 pid = getpid();
Damien Miller95def091999-11-25 00:26:21 +11001335 break;
Damien Miller37023962000-07-11 17:31:38 +10001336 } else {
1337 /*
1338 * Normal production daemon. Fork, and have
1339 * the child process the connection. The
1340 * parent continues listening.
1341 */
1342 if ((pid = fork()) == 0) {
1343 /*
1344 * Child. Close the listening and max_startup
1345 * sockets. Start using the accepted socket.
1346 * Reinitialize logging (since our pid has
1347 * changed). We break out of the loop to handle
1348 * the connection.
1349 */
1350 startup_pipe = startup_p[1];
Ben Lindstromd84df982001-12-06 16:35:40 +00001351 close_startup_pipes();
Damien Miller37023962000-07-11 17:31:38 +10001352 close_listen_socks();
1353 sock_in = newsock;
1354 sock_out = newsock;
Kevin Stevesec84dc12000-12-13 17:45:15 +00001355 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller37023962000-07-11 17:31:38 +10001356 break;
1357 }
Damien Miller95def091999-11-25 00:26:21 +11001358 }
Damien Miller37023962000-07-11 17:31:38 +10001359
1360 /* Parent. Stay in the loop. */
1361 if (pid < 0)
1362 error("fork: %.100s", strerror(errno));
1363 else
Ben Lindstromce0f6342002-06-11 16:42:49 +00001364 debug("Forked child %ld.", (long)pid);
Damien Miller37023962000-07-11 17:31:38 +10001365
1366 close(startup_p[1]);
1367
1368 /* Mark that the key has been used (it was "given" to the child). */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001369 if ((options.protocol & SSH_PROTO_1) &&
1370 key_used == 0) {
1371 /* Schedule server key regeneration alarm. */
1372 signal(SIGALRM, key_regeneration_alarm);
1373 alarm(options.key_regeneration_time);
1374 key_used = 1;
1375 }
Damien Miller37023962000-07-11 17:31:38 +10001376
1377 arc4random_stir();
1378
1379 /* Close the new socket (the child is now taking care of it). */
1380 close(newsock);
Damien Miller95def091999-11-25 00:26:21 +11001381 }
Damien Miller34132e52000-01-14 15:45:46 +11001382 /* child process check (or debug mode) */
1383 if (num_listen_socks < 0)
1384 break;
Damien Miller95def091999-11-25 00:26:21 +11001385 }
1386 }
1387
1388 /* This is the child processing a new connection. */
1389
Damien Miller5428f641999-11-25 11:54:57 +11001390 /*
Ben Lindstrom17401b62002-05-15 16:17:56 +00001391 * Create a new session and process group since the 4.4BSD
1392 * setlogin() affects the entire process group. We don't
1393 * want the child to be able to affect the parent.
1394 */
Kevin Stevesc5041ac2002-05-21 17:50:21 +00001395#if 0
1396 /* XXX: this breaks Solaris */
Ben Lindstrom57f08002002-06-23 00:37:10 +00001397 if (!debug_flag && !inetd_flag && setsid() < 0)
Ben Lindstrom17401b62002-05-15 16:17:56 +00001398 error("setsid: %.100s", strerror(errno));
Kevin Stevesc5041ac2002-05-21 17:50:21 +00001399#endif
Ben Lindstrom17401b62002-05-15 16:17:56 +00001400
1401 /*
Damien Miller5428f641999-11-25 11:54:57 +11001402 * Disable the key regeneration alarm. We will not regenerate the
1403 * key since we are no longer in a position to give it to anyone. We
1404 * will not restart on SIGHUP since it no longer makes sense.
1405 */
Damien Miller95def091999-11-25 00:26:21 +11001406 alarm(0);
1407 signal(SIGALRM, SIG_DFL);
1408 signal(SIGHUP, SIG_DFL);
1409 signal(SIGTERM, SIG_DFL);
1410 signal(SIGQUIT, SIG_DFL);
1411 signal(SIGCHLD, SIG_DFL);
Damien Miller4e0f5e12000-08-29 11:05:50 +11001412 signal(SIGINT, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +11001413
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001414 /* Set keepalives if requested. */
1415 if (options.keepalives &&
Ben Lindstrom733a2352002-03-05 01:31:28 +00001416 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001417 sizeof(on)) < 0)
1418 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1419
Damien Miller5428f641999-11-25 11:54:57 +11001420 /*
1421 * Register our connection. This turns encryption off because we do
1422 * not have a key.
1423 */
Damien Miller95def091999-11-25 00:26:21 +11001424 packet_set_connection(sock_in, sock_out);
1425
1426 remote_port = get_remote_port();
1427 remote_ip = get_remote_ipaddr();
1428
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001429#ifdef LIBWRAP
Damien Miller6a4a4b92001-11-12 11:07:11 +11001430 /* Check whether logins are denied from this host. */
Damien Miller95def091999-11-25 00:26:21 +11001431 {
1432 struct request_info req;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001433
Ben Lindstromce89dac2001-09-12 16:58:04 +00001434 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
Damien Miller95def091999-11-25 00:26:21 +11001435 fromhost(&req);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001436
Damien Miller95def091999-11-25 00:26:21 +11001437 if (!hosts_access(&req)) {
Damien Miller6a4a4b92001-11-12 11:07:11 +11001438 debug("Connection refused by tcp wrapper");
Ben Lindstrom7de696e2001-03-29 00:45:12 +00001439 refuse(&req);
Damien Miller6a4a4b92001-11-12 11:07:11 +11001440 /* NOTREACHED */
1441 fatal("libwrap refuse returns");
Damien Miller95def091999-11-25 00:26:21 +11001442 }
Damien Miller95def091999-11-25 00:26:21 +11001443 }
Damien Miller34132e52000-01-14 15:45:46 +11001444#endif /* LIBWRAP */
Damien Miller6a4a4b92001-11-12 11:07:11 +11001445
Damien Miller95def091999-11-25 00:26:21 +11001446 /* Log the connection. */
1447 verbose("Connection from %.500s port %d", remote_ip, remote_port);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001448
Damien Miller5428f641999-11-25 11:54:57 +11001449 /*
1450 * We don\'t want to listen forever unless the other side
1451 * successfully authenticates itself. So we set up an alarm which is
1452 * cleared after successful authentication. A limit of zero
1453 * indicates no limit. Note that we don\'t set the alarm in debugging
1454 * mode; it is just annoying to have the server exit just when you
1455 * are about to discover the bug.
1456 */
Damien Miller95def091999-11-25 00:26:21 +11001457 signal(SIGALRM, grace_alarm_handler);
1458 if (!debug_flag)
1459 alarm(options.login_grace_time);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001460
Damien Millerb38eff82000-04-01 11:09:21 +10001461 sshd_exchange_identification(sock_in, sock_out);
Damien Miller5428f641999-11-25 11:54:57 +11001462 /*
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001463 * Check that the connection comes from a privileged port.
Ben Lindstromf666fec2002-06-06 19:51:58 +00001464 * Rhosts-Authentication only makes sense from privileged
Damien Miller5428f641999-11-25 11:54:57 +11001465 * programs. Of course, if the intruder has root access on his local
1466 * machine, he can connect from any port. So do not use these
1467 * authentication methods from machines that you do not trust.
1468 */
Damien Miller654c03f2002-02-13 13:54:44 +11001469 if (options.rhosts_authentication &&
1470 (remote_port >= IPPORT_RESERVED ||
1471 remote_port < IPPORT_RESERVED / 2)) {
Kevin Stevesfcec7f82000-12-15 19:55:48 +00001472 debug("Rhosts Authentication disabled, "
Damien Miller00b61642001-11-12 10:51:23 +11001473 "originating port %d not trusted.", remote_port);
Damien Miller95def091999-11-25 00:26:21 +11001474 options.rhosts_authentication = 0;
Damien Miller95def091999-11-25 00:26:21 +11001475 }
Ben Lindstromec95ed92001-07-04 04:21:14 +00001476#if defined(KRB4) && !defined(KRB5)
Damien Miller34132e52000-01-14 15:45:46 +11001477 if (!packet_connection_is_ipv4() &&
1478 options.kerberos_authentication) {
1479 debug("Kerberos Authentication disabled, only available for IPv4.");
1480 options.kerberos_authentication = 0;
1481 }
Ben Lindstromec95ed92001-07-04 04:21:14 +00001482#endif /* KRB4 && !KRB5 */
Ben Lindstromf79aeff2001-02-10 21:27:11 +00001483#ifdef AFS
1484 /* If machine has AFS, set process authentication group. */
1485 if (k_hasafs()) {
1486 k_setpag();
1487 k_unlog();
1488 }
1489#endif /* AFS */
Damien Miller34132e52000-01-14 15:45:46 +11001490
Damien Miller95def091999-11-25 00:26:21 +11001491 packet_set_nonblocking();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001492
Ben Lindstrom943481c2002-03-22 03:43:46 +00001493 if (use_privsep)
1494 if ((authctxt = privsep_preauth()) != NULL)
1495 goto authenticated;
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001496
Damien Miller396691a2000-01-20 22:44:08 +11001497 /* perform the key exchange */
Damien Miller396691a2000-01-20 22:44:08 +11001498 /* authenticate user and start session */
Damien Millerefb4afe2000-04-12 18:45:05 +10001499 if (compat20) {
1500 do_ssh2_kex();
Ben Lindstrom73ab9ba2002-03-22 01:27:35 +00001501 authctxt = do_authentication2();
Damien Millerefb4afe2000-04-12 18:45:05 +10001502 } else {
1503 do_ssh1_kex();
Ben Lindstrom73ab9ba2002-03-22 01:27:35 +00001504 authctxt = do_authentication();
Damien Millerefb4afe2000-04-12 18:45:05 +10001505 }
Ben Lindstrom943481c2002-03-22 03:43:46 +00001506 /*
1507 * If we use privilege separation, the unprivileged child transfers
1508 * the current keystate and exits
1509 */
1510 if (use_privsep) {
Ben Lindstrom7339b2a2002-05-15 16:25:01 +00001511 mm_send_keystate(pmonitor);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001512 exit(0);
Ben Lindstrom943481c2002-03-22 03:43:46 +00001513 }
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001514
1515 authenticated:
Ben Lindstrom6328ab32002-03-22 02:54:23 +00001516 /*
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001517 * In privilege separation, we fork another child and prepare
1518 * file descriptor passing.
1519 */
1520 if (use_privsep) {
Ben Lindstrom943481c2002-03-22 03:43:46 +00001521 privsep_postauth(authctxt);
1522 /* the monitor process [priv] will not return */
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001523 if (!compat20)
1524 destroy_sensitive_data();
1525 }
Ben Lindstrom73ab9ba2002-03-22 01:27:35 +00001526
1527 /* Perform session preparation. */
1528 do_authenticated(authctxt);
1529
Damien Miller3a5b0232002-03-13 13:19:42 +11001530 /* The connection has been terminated. */
1531 verbose("Closing connection to %.100s", remote_ip);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001532
Damien Millerbeb4ba51999-12-28 15:09:35 +11001533#ifdef USE_PAM
Damien Millere72b7af1999-12-30 15:08:44 +11001534 finish_pam();
Damien Millerbeb4ba51999-12-28 15:09:35 +11001535#endif /* USE_PAM */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001536
Damien Miller95def091999-11-25 00:26:21 +11001537 packet_close();
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001538
1539 if (use_privsep)
1540 mm_terminate();
1541
Damien Miller95def091999-11-25 00:26:21 +11001542 exit(0);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001543}
1544
Damien Miller95def091999-11-25 00:26:21 +11001545/*
Ben Lindstromabcb1452002-03-22 01:10:21 +00001546 * Decrypt session_key_int using our private server key and private host key
1547 * (key with larger modulus first).
1548 */
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001549int
Ben Lindstromabcb1452002-03-22 01:10:21 +00001550ssh1_session_key(BIGNUM *session_key_int)
1551{
1552 int rsafail = 0;
1553
1554 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1555 /* Server key has bigger modulus. */
1556 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1557 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1558 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1559 get_remote_ipaddr(),
1560 BN_num_bits(sensitive_data.server_key->rsa->n),
1561 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1562 SSH_KEY_BITS_RESERVED);
1563 }
1564 if (rsa_private_decrypt(session_key_int, session_key_int,
1565 sensitive_data.server_key->rsa) <= 0)
1566 rsafail++;
1567 if (rsa_private_decrypt(session_key_int, session_key_int,
1568 sensitive_data.ssh1_host_key->rsa) <= 0)
1569 rsafail++;
1570 } else {
1571 /* Host key has bigger modulus (or they are equal). */
1572 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1573 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1574 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1575 get_remote_ipaddr(),
1576 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1577 BN_num_bits(sensitive_data.server_key->rsa->n),
1578 SSH_KEY_BITS_RESERVED);
1579 }
1580 if (rsa_private_decrypt(session_key_int, session_key_int,
1581 sensitive_data.ssh1_host_key->rsa) < 0)
1582 rsafail++;
1583 if (rsa_private_decrypt(session_key_int, session_key_int,
1584 sensitive_data.server_key->rsa) < 0)
1585 rsafail++;
1586 }
1587 return (rsafail);
1588}
1589/*
Damien Miller396691a2000-01-20 22:44:08 +11001590 * SSH1 key exchange
Damien Miller95def091999-11-25 00:26:21 +11001591 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001592static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001593do_ssh1_kex(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001594{
Damien Miller95def091999-11-25 00:26:21 +11001595 int i, len;
Damien Miller7650bc62001-01-30 09:27:26 +11001596 int rsafail = 0;
Damien Miller95def091999-11-25 00:26:21 +11001597 BIGNUM *session_key_int;
Ben Lindstrom46c16222000-12-22 01:43:59 +00001598 u_char session_key[SSH_SESSION_KEY_LENGTH];
1599 u_char cookie[8];
1600 u_int cipher_type, auth_mask, protocol_flags;
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +00001601 u_int32_t rnd = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001602
Damien Miller5428f641999-11-25 11:54:57 +11001603 /*
1604 * Generate check bytes that the client must send back in the user
1605 * packet in order for it to be accepted; this is used to defy ip
1606 * spoofing attacks. Note that this only works against somebody
1607 * doing IP spoofing from a remote machine; any machine on the local
1608 * network can still see outgoing packets and catch the random
1609 * cookie. This only affects rhosts authentication, and this is one
1610 * of the reasons why it is inherently insecure.
1611 */
Damien Miller95def091999-11-25 00:26:21 +11001612 for (i = 0; i < 8; i++) {
1613 if (i % 4 == 0)
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +00001614 rnd = arc4random();
1615 cookie[i] = rnd & 0xff;
1616 rnd >>= 8;
Damien Miller95def091999-11-25 00:26:21 +11001617 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001618
Damien Miller5428f641999-11-25 11:54:57 +11001619 /*
1620 * Send our public key. We include in the packet 64 bits of random
1621 * data that must be matched in the reply in order to prevent IP
1622 * spoofing.
1623 */
Damien Miller95def091999-11-25 00:26:21 +11001624 packet_start(SSH_SMSG_PUBLIC_KEY);
1625 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001626 packet_put_char(cookie[i]);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001627
Damien Miller95def091999-11-25 00:26:21 +11001628 /* Store our public server RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001629 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1630 packet_put_bignum(sensitive_data.server_key->rsa->e);
1631 packet_put_bignum(sensitive_data.server_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001632
Damien Miller95def091999-11-25 00:26:21 +11001633 /* Store our public host RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001634 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1635 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1636 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001637
Damien Miller95def091999-11-25 00:26:21 +11001638 /* Put protocol flags. */
1639 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001640
Damien Miller95def091999-11-25 00:26:21 +11001641 /* Declare which ciphers we support. */
Damien Miller874d77b2000-10-14 16:23:11 +11001642 packet_put_int(cipher_mask_ssh1(0));
Damien Miller95def091999-11-25 00:26:21 +11001643
1644 /* Declare supported authentication types. */
1645 auth_mask = 0;
1646 if (options.rhosts_authentication)
1647 auth_mask |= 1 << SSH_AUTH_RHOSTS;
1648 if (options.rhosts_rsa_authentication)
1649 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1650 if (options.rsa_authentication)
1651 auth_mask |= 1 << SSH_AUTH_RSA;
Ben Lindstromec95ed92001-07-04 04:21:14 +00001652#if defined(KRB4) || defined(KRB5)
Damien Miller95def091999-11-25 00:26:21 +11001653 if (options.kerberos_authentication)
1654 auth_mask |= 1 << SSH_AUTH_KERBEROS;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001655#endif
Ben Lindstromec95ed92001-07-04 04:21:14 +00001656#if defined(AFS) || defined(KRB5)
Damien Miller95def091999-11-25 00:26:21 +11001657 if (options.kerberos_tgt_passing)
1658 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
Ben Lindstromec95ed92001-07-04 04:21:14 +00001659#endif
1660#ifdef AFS
Damien Miller95def091999-11-25 00:26:21 +11001661 if (options.afs_token_passing)
1662 auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001663#endif
Ben Lindstrom551ea372001-06-05 18:56:16 +00001664 if (options.challenge_response_authentication == 1)
Damien Miller95def091999-11-25 00:26:21 +11001665 auth_mask |= 1 << SSH_AUTH_TIS;
Damien Miller95def091999-11-25 00:26:21 +11001666 if (options.password_authentication)
1667 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1668 packet_put_int(auth_mask);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001669
Damien Miller95def091999-11-25 00:26:21 +11001670 /* Send the packet and wait for it to be sent. */
1671 packet_send();
1672 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001673
Damien Miller0bc1bd82000-11-13 22:57:25 +11001674 debug("Sent %d bit server key and %d bit host key.",
1675 BN_num_bits(sensitive_data.server_key->rsa->n),
1676 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001677
Damien Miller95def091999-11-25 00:26:21 +11001678 /* Read clients reply (cipher type and session key). */
Damien Millerdff50992002-01-22 23:16:32 +11001679 packet_read_expect(SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001680
Damien Miller50945fa1999-12-09 10:31:37 +11001681 /* Get cipher type and check whether we accept this. */
Damien Miller95def091999-11-25 00:26:21 +11001682 cipher_type = packet_get_char();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001683
Damien Miller874d77b2000-10-14 16:23:11 +11001684 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
Damien Miller50945fa1999-12-09 10:31:37 +11001685 packet_disconnect("Warning: client selects unsupported cipher.");
1686
Damien Miller95def091999-11-25 00:26:21 +11001687 /* Get check bytes from the packet. These must match those we
1688 sent earlier with the public key packet. */
1689 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001690 if (cookie[i] != packet_get_char())
Damien Miller95def091999-11-25 00:26:21 +11001691 packet_disconnect("IP Spoofing check bytes do not match.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001692
Damien Miller95def091999-11-25 00:26:21 +11001693 debug("Encryption type: %.200s", cipher_name(cipher_type));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001694
Damien Miller95def091999-11-25 00:26:21 +11001695 /* Get the encrypted integer. */
Damien Millerda755162002-01-22 23:09:22 +11001696 if ((session_key_int = BN_new()) == NULL)
1697 fatal("do_ssh1_kex: BN_new failed");
Damien Millerd432ccf2002-01-22 23:14:44 +11001698 packet_get_bignum(session_key_int);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001699
Damien Miller95def091999-11-25 00:26:21 +11001700 protocol_flags = packet_get_int();
1701 packet_set_protocol_flags(protocol_flags);
Damien Miller48b03fc2002-01-22 23:11:40 +11001702 packet_check_eom();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001703
Ben Lindstromabcb1452002-03-22 01:10:21 +00001704 /* Decrypt session_key_int using host/server keys */
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001705 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1706
Damien Miller5428f641999-11-25 11:54:57 +11001707 /*
1708 * Extract session key from the decrypted integer. The key is in the
1709 * least significant 256 bits of the integer; the first byte of the
1710 * key is in the highest bits.
1711 */
Damien Miller7650bc62001-01-30 09:27:26 +11001712 if (!rsafail) {
1713 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1714 len = BN_num_bytes(session_key_int);
1715 if (len < 0 || len > sizeof(session_key)) {
1716 error("do_connection: bad session key len from %s: "
Ben Lindstrom31ca54a2001-02-09 02:11:24 +00001717 "session_key_int %d > sizeof(session_key) %lu",
1718 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
Damien Miller7650bc62001-01-30 09:27:26 +11001719 rsafail++;
1720 } else {
1721 memset(session_key, 0, sizeof(session_key));
1722 BN_bn2bin(session_key_int,
1723 session_key + sizeof(session_key) - len);
Ben Lindstromeb648a72001-03-05 06:00:29 +00001724
1725 compute_session_id(session_id, cookie,
1726 sensitive_data.ssh1_host_key->rsa->n,
1727 sensitive_data.server_key->rsa->n);
1728 /*
1729 * Xor the first 16 bytes of the session key with the
1730 * session id.
1731 */
1732 for (i = 0; i < 16; i++)
1733 session_key[i] ^= session_id[i];
Damien Miller7650bc62001-01-30 09:27:26 +11001734 }
1735 }
1736 if (rsafail) {
Ben Lindstromeb648a72001-03-05 06:00:29 +00001737 int bytes = BN_num_bytes(session_key_int);
Ben Lindstrom13c5d3b2002-02-26 18:00:48 +00001738 u_char *buf = xmalloc(bytes);
Ben Lindstromeb648a72001-03-05 06:00:29 +00001739 MD5_CTX md;
1740
Damien Miller7650bc62001-01-30 09:27:26 +11001741 log("do_connection: generating a fake encryption key");
Ben Lindstromeb648a72001-03-05 06:00:29 +00001742 BN_bn2bin(session_key_int, buf);
1743 MD5_Init(&md);
1744 MD5_Update(&md, buf, bytes);
1745 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1746 MD5_Final(session_key, &md);
1747 MD5_Init(&md);
1748 MD5_Update(&md, session_key, 16);
1749 MD5_Update(&md, buf, bytes);
1750 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1751 MD5_Final(session_key + 16, &md);
1752 memset(buf, 0, bytes);
1753 xfree(buf);
Ben Lindstrom941ac822001-03-05 06:25:23 +00001754 for (i = 0; i < 16; i++)
1755 session_id[i] = session_key[i] ^ session_key[i + 16];
Damien Miller7650bc62001-01-30 09:27:26 +11001756 }
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001757 /* Destroy the private and public keys. No longer. */
Damien Miller3a5b0232002-03-13 13:19:42 +11001758 destroy_sensitive_data();
Ben Lindstromeb648a72001-03-05 06:00:29 +00001759
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001760 if (use_privsep)
1761 mm_ssh1_session_id(session_id);
1762
Damien Miller396691a2000-01-20 22:44:08 +11001763 /* Destroy the decrypted integer. It is no longer needed. */
1764 BN_clear_free(session_key_int);
1765
Damien Miller95def091999-11-25 00:26:21 +11001766 /* Set the session key. From this on all communications will be encrypted. */
1767 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001768
Damien Miller95def091999-11-25 00:26:21 +11001769 /* Destroy our copy of the session key. It is no longer needed. */
1770 memset(session_key, 0, sizeof(session_key));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001771
Damien Miller95def091999-11-25 00:26:21 +11001772 debug("Received session key; encryption turned on.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001773
Ben Lindstromf666fec2002-06-06 19:51:58 +00001774 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
Damien Miller95def091999-11-25 00:26:21 +11001775 packet_start(SSH_SMSG_SUCCESS);
1776 packet_send();
1777 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001778}
Damien Millerefb4afe2000-04-12 18:45:05 +10001779
1780/*
1781 * SSH2 key exchange: diffie-hellman-group1-sha1
1782 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001783static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001784do_ssh2_kex(void)
Damien Millerefb4afe2000-04-12 18:45:05 +10001785{
Damien Millerefb4afe2000-04-12 18:45:05 +10001786 Kex *kex;
Damien Millerefb4afe2000-04-12 18:45:05 +10001787
Damien Miller78928792000-04-12 20:17:38 +10001788 if (options.ciphers != NULL) {
Damien Miller4af51302000-04-16 11:18:38 +10001789 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
Damien Miller78928792000-04-12 20:17:38 +10001790 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1791 }
Damien Millera0ff4662001-03-30 10:49:35 +10001792 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1793 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1794 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1795 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1796
Ben Lindstrom06b33aa2001-02-15 03:01:59 +00001797 if (options.macs != NULL) {
1798 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1799 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1800 }
Ben Lindstrom23e0f662002-06-21 01:09:47 +00001801 if (!options.compression) {
1802 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1803 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1804 }
Damien Miller0bc1bd82000-11-13 22:57:25 +11001805 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1806
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001807 /* start key exchange */
Ben Lindstrom238abf62001-04-04 17:52:53 +00001808 kex = kex_setup(myproposal);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001809 kex->server = 1;
1810 kex->client_version_string=client_version_string;
1811 kex->server_version_string=server_version_string;
1812 kex->load_host_key=&get_hostkey_by_type;
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001813 kex->host_key_index=&get_hostkey_index;
Damien Millerefb4afe2000-04-12 18:45:05 +10001814
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001815 xxx_kex = kex;
1816
Ben Lindstrombe2cc432001-04-04 23:46:07 +00001817 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
Damien Miller874d77b2000-10-14 16:23:11 +11001818
Ben Lindstrom2d90e002001-04-04 02:00:54 +00001819 session_id2 = kex->session_id;
1820 session_id2_len = kex->session_id_len;
1821
Damien Miller874d77b2000-10-14 16:23:11 +11001822#ifdef DEBUG_KEXDH
1823 /* send 1st encrypted/maced/compressed message */
1824 packet_start(SSH2_MSG_IGNORE);
1825 packet_put_cstring("markus");
1826 packet_send();
1827 packet_write_wait();
1828#endif
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001829 debug("KEX done");
Damien Millerefb4afe2000-04-12 18:45:05 +10001830}