blob: b45bc0abc348b8bb1f4a54bfc9ce3e3d3efda16b [file] [log] [blame]
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"
Darren Tucker3175eb92003-12-09 19:15:11 +110045RCSID("$OpenBSD: sshd.c,v 1.282 2003/12/02 17:01:15 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 */
115int IPv4or6 = AF_UNSPEC;
116
Damien Miller95def091999-11-25 00:26:21 +1100117/*
118 * Debug mode flag. This can be set on the command line. If debug
119 * mode is enabled, extra debugging output will be sent to the system
120 * log, the daemon will not go to background, and will exit after processing
121 * the first connection.
122 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000123int debug_flag = 0;
124
Ben Lindstrom794325a2001-08-06 21:09:07 +0000125/* Flag indicating that the daemon should only test the configuration and keys. */
126int test_flag = 0;
127
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000128/* Flag indicating that the daemon is being started from inetd. */
129int inetd_flag = 0;
130
Ben Lindstromc72745a2000-12-02 19:03:54 +0000131/* Flag indicating that sshd should not detach and become a daemon. */
132int no_daemon_flag = 0;
133
Damien Miller5ce662a1999-11-11 17:57:39 +1100134/* debug goes to stderr unless inetd_flag is set */
135int log_stderr = 0;
136
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000137/* Saved arguments to main(). */
138char **saved_argv;
Damien Millerb8c656e2000-06-28 15:22:41 +1000139int saved_argc;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000140
Damien Miller5428f641999-11-25 11:54:57 +1100141/*
Damien Miller34132e52000-01-14 15:45:46 +1100142 * The sockets that the server is listening; this is used in the SIGHUP
143 * signal handler.
Damien Miller5428f641999-11-25 11:54:57 +1100144 */
Damien Miller34132e52000-01-14 15:45:46 +1100145#define MAX_LISTEN_SOCKS 16
146int listen_socks[MAX_LISTEN_SOCKS];
147int num_listen_socks = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000148
Damien Miller5428f641999-11-25 11:54:57 +1100149/*
150 * the client's version string, passed by sshd2 in compat mode. if != NULL,
151 * sshd will skip the version-number exchange
152 */
Damien Miller95def091999-11-25 00:26:21 +1100153char *client_version_string = NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000154char *server_version_string = NULL;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000155
Ben Lindstrom8ac91062001-04-04 17:57:54 +0000156/* for rekeying XXX fixme */
157Kex *xxx_kex;
158
Damien Miller5428f641999-11-25 11:54:57 +1100159/*
160 * Any really sensitive data in the application is contained in this
161 * structure. The idea is that this structure could be locked into memory so
162 * that the pages do not get written into swap. However, there are some
163 * problems. The private key contains BIGNUMs, and we do not (in principle)
164 * have access to the internals of them, and locking just the structure is
165 * not very useful. Currently, memory locking is not implemented.
166 */
Damien Miller95def091999-11-25 00:26:21 +1100167struct {
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000168 Key *server_key; /* ephemeral server key */
Damien Miller0bc1bd82000-11-13 22:57:25 +1100169 Key *ssh1_host_key; /* ssh1 host key */
170 Key **host_keys; /* all private host keys */
171 int have_ssh1_key;
172 int have_ssh2_key;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000173 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000174} sensitive_data;
175
Damien Miller5428f641999-11-25 11:54:57 +1100176/*
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000177 * Flag indicating whether the RSA server key needs to be regenerated.
178 * Is set in the SIGALRM handler and cleared when the key is regenerated.
Damien Miller5428f641999-11-25 11:54:57 +1100179 */
Ben Lindstrom5e71c542001-12-06 16:48:14 +0000180static volatile sig_atomic_t key_do_regen = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000181
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000182/* This is set to true when a signal is received. */
Ben Lindstrom5e71c542001-12-06 16:48:14 +0000183static volatile sig_atomic_t received_sighup = 0;
184static volatile sig_atomic_t received_sigterm = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000185
Damien Millerb38eff82000-04-01 11:09:21 +1000186/* session identifier, used by RSA-auth */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000187u_char session_id[16];
Damien Millerb38eff82000-04-01 11:09:21 +1000188
Damien Millereba71ba2000-04-29 23:57:08 +1000189/* same for ssh2 */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000190u_char *session_id2 = NULL;
Darren Tucker502d3842003-06-28 12:38:01 +1000191u_int session_id2_len = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000192
Damien Miller942da032000-08-18 13:59:06 +1000193/* record remote hostname or ip */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000194u_int utmp_len = MAXHOSTNAMELEN;
Damien Miller942da032000-08-18 13:59:06 +1000195
Ben Lindstromd84df982001-12-06 16:35:40 +0000196/* options.max_startup sized array of fd ints */
197int *startup_pipes = NULL;
198int startup_pipe; /* in child */
199
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000200/* variables used for privilege separation */
Damien Miller8e7fb332003-02-24 12:03:03 +1100201int use_privsep;
202struct monitor *pmonitor;
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000203
Darren Tuckerb9aa0a02003-07-08 22:59:59 +1000204/* message to be displayed after login */
205Buffer loginmsg;
206
Darren Tucker3e33cec2003-10-02 16:12:36 +1000207/* global authentication context */
208Authctxt *the_authctxt = NULL;
209
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000210/* Prototypes for various functions defined later in this file. */
Ben Lindstrombba81212001-06-25 05:01:22 +0000211void destroy_sensitive_data(void);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000212void demote_sensitive_data(void);
Damien Miller98c7ad62000-03-09 21:27:49 +1100213
Ben Lindstrombba81212001-06-25 05:01:22 +0000214static void do_ssh1_kex(void);
215static void do_ssh2_kex(void);
Damien Miller874d77b2000-10-14 16:23:11 +1100216
Damien Miller98c7ad62000-03-09 21:27:49 +1100217/*
Damien Miller34132e52000-01-14 15:45:46 +1100218 * Close all listening sockets
219 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000220static void
Damien Miller34132e52000-01-14 15:45:46 +1100221close_listen_socks(void)
222{
223 int i;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000224
Damien Miller34132e52000-01-14 15:45:46 +1100225 for (i = 0; i < num_listen_socks; i++)
226 close(listen_socks[i]);
227 num_listen_socks = -1;
228}
229
Ben Lindstromd84df982001-12-06 16:35:40 +0000230static void
231close_startup_pipes(void)
232{
233 int i;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000234
Ben Lindstromd84df982001-12-06 16:35:40 +0000235 if (startup_pipes)
236 for (i = 0; i < options.max_startups; i++)
237 if (startup_pipes[i] != -1)
238 close(startup_pipes[i]);
239}
240
Damien Miller34132e52000-01-14 15:45:46 +1100241/*
Damien Miller95def091999-11-25 00:26:21 +1100242 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
243 * the effect is to reread the configuration file (and to regenerate
244 * the server key).
245 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000246static void
Damien Miller95def091999-11-25 00:26:21 +1100247sighup_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000248{
Ben Lindstrom07958482001-12-06 16:19:01 +0000249 int save_errno = errno;
250
Damien Miller95def091999-11-25 00:26:21 +1100251 received_sighup = 1;
252 signal(SIGHUP, sighup_handler);
Ben Lindstrom07958482001-12-06 16:19:01 +0000253 errno = save_errno;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000254}
255
Damien Miller95def091999-11-25 00:26:21 +1100256/*
257 * Called from the main program after receiving SIGHUP.
258 * Restarts the server.
259 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000260static void
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000261sighup_restart(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000262{
Damien Miller996acd22003-04-09 20:59:48 +1000263 logit("Received SIGHUP; restarting.");
Damien Miller34132e52000-01-14 15:45:46 +1100264 close_listen_socks();
Ben Lindstromd84df982001-12-06 16:35:40 +0000265 close_startup_pipes();
Damien Miller95def091999-11-25 00:26:21 +1100266 execv(saved_argv[0], saved_argv);
Damien Miller996acd22003-04-09 20:59:48 +1000267 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
Ben Lindstrom822b6342002-06-23 21:38:49 +0000268 strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100269 exit(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000270}
271
Damien Miller95def091999-11-25 00:26:21 +1100272/*
273 * Generic signal handler for terminating signals in the master daemon.
Damien Miller95def091999-11-25 00:26:21 +1100274 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000275static void
Damien Miller95def091999-11-25 00:26:21 +1100276sigterm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000277{
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000278 received_sigterm = sig;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000279}
280
Damien Miller95def091999-11-25 00:26:21 +1100281/*
282 * SIGCHLD handler. This is called whenever a child dies. This will then
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000283 * reap any zombies left by exited children.
Damien Miller95def091999-11-25 00:26:21 +1100284 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000285static void
Damien Miller95def091999-11-25 00:26:21 +1100286main_sigchld_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000287{
Damien Miller95def091999-11-25 00:26:21 +1100288 int save_errno = errno;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000289 pid_t pid;
Damien Miller95def091999-11-25 00:26:21 +1100290 int status;
Damien Miller431f66b1999-11-21 18:31:57 +1100291
Ben Lindstrom47fd8112002-04-02 20:48:19 +0000292 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
293 (pid < 0 && errno == EINTR))
Damien Miller95def091999-11-25 00:26:21 +1100294 ;
Damien Miller431f66b1999-11-21 18:31:57 +1100295
Damien Miller95def091999-11-25 00:26:21 +1100296 signal(SIGCHLD, main_sigchld_handler);
297 errno = save_errno;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000298}
299
Damien Miller95def091999-11-25 00:26:21 +1100300/*
301 * Signal handler for the alarm after the login grace period has expired.
302 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000303static void
Damien Miller95def091999-11-25 00:26:21 +1100304grace_alarm_handler(int sig)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000305{
Ben Lindstromec46e0b2001-06-09 01:27:31 +0000306 /* XXX no idea how fix this signal handler */
307
Damien Miller95def091999-11-25 00:26:21 +1100308 /* Log error and exit. */
Damien Millerd27a76d2002-09-27 13:22:31 +1000309 fatal("Timeout before authentication for %s", get_remote_ipaddr());
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000310}
311
Damien Miller95def091999-11-25 00:26:21 +1100312/*
Damien Miller95def091999-11-25 00:26:21 +1100313 * Signal handler for the key regeneration alarm. Note that this
314 * alarm only occurs in the daemon waiting for connections, and it does not
315 * do anything with the private key or random state before forking.
316 * Thus there should be no concurrency control/asynchronous execution
317 * problems.
318 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000319static void
Ben Lindstromca42d5f2001-03-09 18:25:32 +0000320generate_ephemeral_server_key(void)
Damien Miller0bc1bd82000-11-13 22:57:25 +1100321{
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +0000322 u_int32_t rnd = 0;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000323 int i;
324
Ben Lindstroma3700052001-04-05 23:26:32 +0000325 verbose("Generating %s%d bit RSA key.",
Damien Millerff75ac42001-03-30 10:50:32 +1000326 sensitive_data.server_key ? "new " : "", options.server_key_bits);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100327 if (sensitive_data.server_key != NULL)
328 key_free(sensitive_data.server_key);
Ben Lindstroma3700052001-04-05 23:26:32 +0000329 sensitive_data.server_key = key_generate(KEY_RSA1,
Damien Millerff75ac42001-03-30 10:50:32 +1000330 options.server_key_bits);
331 verbose("RSA key generation complete.");
Ben Lindstromeb648a72001-03-05 06:00:29 +0000332
333 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
334 if (i % 4 == 0)
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +0000335 rnd = arc4random();
336 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
337 rnd >>= 8;
Ben Lindstromeb648a72001-03-05 06:00:29 +0000338 }
339 arc4random_stir();
Damien Miller0bc1bd82000-11-13 22:57:25 +1100340}
Ben Lindstrom2f959b42001-01-11 06:20:23 +0000341
Ben Lindstrombba81212001-06-25 05:01:22 +0000342static void
Damien Miller95def091999-11-25 00:26:21 +1100343key_regeneration_alarm(int sig)
344{
345 int save_errno = errno;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000346
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000347 signal(SIGALRM, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +1100348 errno = save_errno;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000349 key_do_regen = 1;
Damien Miller95def091999-11-25 00:26:21 +1100350}
351
Ben Lindstrombba81212001-06-25 05:01:22 +0000352static void
Damien Millerb38eff82000-04-01 11:09:21 +1000353sshd_exchange_identification(int sock_in, int sock_out)
354{
Damien Miller78928792000-04-12 20:17:38 +1000355 int i, mismatch;
Damien Millerb38eff82000-04-01 11:09:21 +1000356 int remote_major, remote_minor;
Damien Miller78928792000-04-12 20:17:38 +1000357 int major, minor;
Damien Millerb38eff82000-04-01 11:09:21 +1000358 char *s;
359 char buf[256]; /* Must not be larger than remote_version. */
360 char remote_version[256]; /* Must be at least as big as buf. */
361
Damien Miller78928792000-04-12 20:17:38 +1000362 if ((options.protocol & SSH_PROTO_1) &&
363 (options.protocol & SSH_PROTO_2)) {
364 major = PROTOCOL_MAJOR_1;
365 minor = 99;
366 } else if (options.protocol & SSH_PROTO_2) {
367 major = PROTOCOL_MAJOR_2;
368 minor = PROTOCOL_MINOR_2;
369 } else {
370 major = PROTOCOL_MAJOR_1;
371 minor = PROTOCOL_MINOR_1;
372 }
373 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
Damien Millerb38eff82000-04-01 11:09:21 +1000374 server_version_string = xstrdup(buf);
375
Darren Tuckerfe0078a2003-07-19 19:52:28 +1000376 /* Send our protocol version identification. */
377 if (atomicio(vwrite, sock_out, server_version_string,
378 strlen(server_version_string))
379 != strlen(server_version_string)) {
380 logit("Could not write ident string to %s", get_remote_ipaddr());
Darren Tucker3e33cec2003-10-02 16:12:36 +1000381 cleanup_exit(255);
Darren Tuckerfe0078a2003-07-19 19:52:28 +1000382 }
383
384 /* Read other sides version identification. */
385 memset(buf, 0, sizeof(buf));
386 for (i = 0; i < sizeof(buf) - 1; i++) {
387 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
388 logit("Did not receive identification string from %s",
389 get_remote_ipaddr());
Darren Tucker3e33cec2003-10-02 16:12:36 +1000390 cleanup_exit(255);
Damien Millerb38eff82000-04-01 11:09:21 +1000391 }
Darren Tuckerfe0078a2003-07-19 19:52:28 +1000392 if (buf[i] == '\r') {
393 buf[i] = 0;
394 /* Kludge for F-Secure Macintosh < 1.0.2 */
395 if (i == 12 &&
396 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
Damien Millerb38eff82000-04-01 11:09:21 +1000397 break;
Darren Tuckerfe0078a2003-07-19 19:52:28 +1000398 continue;
Damien Millerb38eff82000-04-01 11:09:21 +1000399 }
Darren Tuckerfe0078a2003-07-19 19:52:28 +1000400 if (buf[i] == '\n') {
401 buf[i] = 0;
402 break;
403 }
Damien Millerb38eff82000-04-01 11:09:21 +1000404 }
Darren Tuckerfe0078a2003-07-19 19:52:28 +1000405 buf[sizeof(buf) - 1] = 0;
406 client_version_string = xstrdup(buf);
Damien Millerb38eff82000-04-01 11:09:21 +1000407
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";
Darren Tucker9f63f222003-07-03 13:46:56 +1000415 (void) atomicio(vwrite, sock_out, s, strlen(s));
Damien Millerb38eff82000-04-01 11:09:21 +1000416 close(sock_in);
417 close(sock_out);
Damien Miller996acd22003-04-09 20:59:48 +1000418 logit("Bad protocol version identification '%.100s' from %s",
Damien Millerb38eff82000-04-01 11:09:21 +1000419 client_version_string, get_remote_ipaddr());
Darren Tucker3e33cec2003-10-02 16:12:36 +1000420 cleanup_exit(255);
Damien Millerb38eff82000-04-01 11:09:21 +1000421 }
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) {
Damien Miller996acd22003-04-09 20:59:48 +1000428 logit("probed from %s with %s. Don't panic.",
Damien Millere9264972002-09-30 11:59:21 +1000429 get_remote_ipaddr(), client_version_string);
Darren Tucker3e33cec2003-10-02 16:12:36 +1000430 cleanup_exit(255);
Damien Millere9264972002-09-30 11:59:21 +1000431 }
432
Damien Miller27dbe6f2001-03-19 22:36:20 +1100433 if (datafellows & SSH_BUG_SCANNER) {
Damien Miller996acd22003-04-09 20:59:48 +1000434 logit("scanned from %s with %s. Don't panic.",
Damien Miller27dbe6f2001-03-19 22:36:20 +1100435 get_remote_ipaddr(), client_version_string);
Darren Tucker3e33cec2003-10-02 16:12:36 +1000436 cleanup_exit(255);
Damien Miller27dbe6f2001-03-19 22:36:20 +1100437 }
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";
Darren Tucker9f63f222003-07-03 13:46:56 +1000476 (void) atomicio(vwrite, sock_out, s, strlen(s));
Damien Miller78928792000-04-12 20:17:38 +1000477 close(sock_in);
478 close(sock_out);
Damien Miller996acd22003-04-09 20:59:48 +1000479 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
Damien Miller78928792000-04-12 20:17:38 +1000480 get_remote_ipaddr(),
481 server_version_string, client_version_string);
Darren Tucker3e33cec2003-10-02 16:12:36 +1000482 cleanup_exit(255);
Damien Miller78928792000-04-12 20:17:38 +1000483 }
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;
Ben Lindstromfbcc3f72002-06-25 23:24:18 +0000571 if (setgroups(1, gidset) < 0)
572 fatal("setgroups: %.100s", strerror(errno));
573 permanently_set_uid(pw);
574#endif
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000575}
576
Darren Tucker3e33cec2003-10-02 16:12:36 +1000577static int
578privsep_preauth(Authctxt *authctxt)
Ben Lindstrom943481c2002-03-22 03:43:46 +0000579{
Ben Lindstrom943481c2002-03-22 03:43:46 +0000580 int status;
581 pid_t pid;
582
583 /* Set up unprivileged child process to deal with network data */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000584 pmonitor = monitor_init();
Ben Lindstrom943481c2002-03-22 03:43:46 +0000585 /* Store a pointer to the kex for later rekeying */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000586 pmonitor->m_pkex = &xxx_kex;
Ben Lindstrom943481c2002-03-22 03:43:46 +0000587
588 pid = fork();
589 if (pid == -1) {
590 fatal("fork of unprivileged child failed");
591 } else if (pid != 0) {
Ben Lindstromce0f6342002-06-11 16:42:49 +0000592 debug2("Network child is on pid %ld", (long)pid);
Ben Lindstrom943481c2002-03-22 03:43:46 +0000593
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000594 close(pmonitor->m_recvfd);
Darren Tucker3e33cec2003-10-02 16:12:36 +1000595 monitor_child_preauth(authctxt, pmonitor);
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000596 close(pmonitor->m_sendfd);
Ben Lindstrom943481c2002-03-22 03:43:46 +0000597
598 /* Sync memory */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000599 monitor_sync(pmonitor);
Ben Lindstrom943481c2002-03-22 03:43:46 +0000600
601 /* Wait for the child's exit status */
Ben Lindstrom47fd8112002-04-02 20:48:19 +0000602 while (waitpid(pid, &status, 0) < 0)
603 if (errno != EINTR)
604 break;
Darren Tucker3e33cec2003-10-02 16:12:36 +1000605 return (1);
Ben Lindstrom943481c2002-03-22 03:43:46 +0000606 } else {
607 /* child */
608
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000609 close(pmonitor->m_sendfd);
Ben Lindstrom943481c2002-03-22 03:43:46 +0000610
611 /* Demote the child */
612 if (getuid() == 0 || geteuid() == 0)
613 privsep_preauth_child();
Ben Lindstromf90f58d2002-03-26 01:53:03 +0000614 setproctitle("%s", "[net]");
Ben Lindstrom943481c2002-03-22 03:43:46 +0000615 }
Darren Tucker3e33cec2003-10-02 16:12:36 +1000616 return (0);
Ben Lindstrom943481c2002-03-22 03:43:46 +0000617}
618
Ben Lindstrom08105192002-03-22 02:50:06 +0000619static void
Ben Lindstrom943481c2002-03-22 03:43:46 +0000620privsep_postauth(Authctxt *authctxt)
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000621{
Tim Rice9dd30812002-07-07 13:43:36 -0700622#ifdef DISABLE_FD_PASSING
Tim Rice8eff3192002-06-25 15:35:15 -0700623 if (1) {
624#else
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000625 if (authctxt->pw->pw_uid == 0 || options.use_login) {
Tim Rice8eff3192002-06-25 15:35:15 -0700626#endif
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000627 /* File descriptor passing is broken or root login */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000628 monitor_apply_keystate(pmonitor);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000629 use_privsep = 0;
630 return;
631 }
Ben Lindstrom6328ab32002-03-22 02:54:23 +0000632
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000633 /* Authentication complete */
634 alarm(0);
635 if (startup_pipe != -1) {
636 close(startup_pipe);
637 startup_pipe = -1;
638 }
639
640 /* New socket pair */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000641 monitor_reinit(pmonitor);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000642
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000643 pmonitor->m_pid = fork();
644 if (pmonitor->m_pid == -1)
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000645 fatal("fork of unprivileged child failed");
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000646 else if (pmonitor->m_pid != 0) {
Ben Lindstromce0f6342002-06-11 16:42:49 +0000647 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000648 close(pmonitor->m_recvfd);
649 monitor_child_postauth(pmonitor);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000650
651 /* NEVERREACHED */
652 exit(0);
653 }
654
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000655 close(pmonitor->m_sendfd);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000656
657 /* Demote the private keys to public keys. */
658 demote_sensitive_data();
659
660 /* Drop privileges */
661 do_setusercontext(authctxt->pw);
662
663 /* It is safe now to apply the key state */
Ben Lindstrom7339b2a2002-05-15 16:25:01 +0000664 monitor_apply_keystate(pmonitor);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000665}
666
Ben Lindstrombba81212001-06-25 05:01:22 +0000667static char *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100668list_hostkey_types(void)
669{
Damien Miller0e3b8722002-01-22 23:26:38 +1100670 Buffer b;
Damien Millerf58b58c2003-11-17 21:18:23 +1100671 const char *p;
672 char *ret;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100673 int i;
Damien Miller0e3b8722002-01-22 23:26:38 +1100674
675 buffer_init(&b);
Damien Miller9f0f5c62001-12-21 14:45:46 +1100676 for (i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100677 Key *key = sensitive_data.host_keys[i];
678 if (key == NULL)
679 continue;
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000680 switch (key->type) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100681 case KEY_RSA:
682 case KEY_DSA:
Damien Miller0e3b8722002-01-22 23:26:38 +1100683 if (buffer_len(&b) > 0)
684 buffer_append(&b, ",", 1);
685 p = key_ssh_name(key);
686 buffer_append(&b, p, strlen(p));
Damien Miller0bc1bd82000-11-13 22:57:25 +1100687 break;
688 }
689 }
Damien Miller0e3b8722002-01-22 23:26:38 +1100690 buffer_append(&b, "\0", 1);
Damien Millerf58b58c2003-11-17 21:18:23 +1100691 ret = xstrdup(buffer_ptr(&b));
Damien Miller0e3b8722002-01-22 23:26:38 +1100692 buffer_free(&b);
Damien Millerf58b58c2003-11-17 21:18:23 +1100693 debug("list_hostkey_types: %s", ret);
694 return ret;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100695}
696
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000697Key *
Damien Miller0bc1bd82000-11-13 22:57:25 +1100698get_hostkey_by_type(int type)
699{
700 int i;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000701
Damien Miller9f0f5c62001-12-21 14:45:46 +1100702 for (i = 0; i < options.num_host_key_files; i++) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100703 Key *key = sensitive_data.host_keys[i];
704 if (key != NULL && key->type == type)
705 return key;
706 }
707 return NULL;
Damien Millerb38eff82000-04-01 11:09:21 +1000708}
709
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000710Key *
711get_hostkey_by_index(int ind)
712{
713 if (ind < 0 || ind >= options.num_host_key_files)
714 return (NULL);
715 return (sensitive_data.host_keys[ind]);
716}
717
718int
719get_hostkey_index(Key *key)
720{
721 int i;
Ben Lindstrom822b6342002-06-23 21:38:49 +0000722
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000723 for (i = 0; i < options.num_host_key_files; i++) {
724 if (key == sensitive_data.host_keys[i])
725 return (i);
726 }
727 return (-1);
728}
729
Damien Miller942da032000-08-18 13:59:06 +1000730/*
731 * returns 1 if connection should be dropped, 0 otherwise.
732 * dropping starts at connection #max_startups_begin with a probability
733 * of (max_startups_rate/100). the probability increases linearly until
734 * all connections are dropped for startups > max_startups
735 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000736static int
Damien Miller942da032000-08-18 13:59:06 +1000737drop_connection(int startups)
738{
739 double p, r;
740
741 if (startups < options.max_startups_begin)
742 return 0;
743 if (startups >= options.max_startups)
744 return 1;
745 if (options.max_startups_rate == 100)
746 return 1;
747
748 p = 100 - options.max_startups_rate;
749 p *= startups - options.max_startups_begin;
750 p /= (double) (options.max_startups - options.max_startups_begin);
751 p += options.max_startups_rate;
752 p /= 100.0;
753 r = arc4random() / (double) UINT_MAX;
754
755 debug("drop_connection: p %g, r %g", p, r);
756 return (r < p) ? 1 : 0;
757}
758
Ben Lindstromade03f62001-12-06 18:22:17 +0000759static void
760usage(void)
761{
Darren Tucker4a250542003-10-03 17:57:24 +1000762 fprintf(stderr, "sshd version %s, %s\n",
763 SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
Ben Lindstromade03f62001-12-06 18:22:17 +0000764 fprintf(stderr, "Usage: %s [options]\n", __progname);
765 fprintf(stderr, "Options:\n");
766 fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
767 fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
768 fprintf(stderr, " -i Started from inetd\n");
769 fprintf(stderr, " -D Do not fork into daemon mode\n");
770 fprintf(stderr, " -t Only test configuration file and keys\n");
771 fprintf(stderr, " -q Quiet (no logging)\n");
772 fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
773 fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
774 fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
775 fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
776 fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
777 _PATH_HOST_KEY_FILE);
778 fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
779 fprintf(stderr, " -4 Use IPv4 only\n");
780 fprintf(stderr, " -6 Use IPv6 only\n");
781 fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n");
782 exit(1);
783}
784
Damien Miller95def091999-11-25 00:26:21 +1100785/*
786 * Main program for the daemon.
787 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000788int
789main(int ac, char **av)
790{
Damien Miller95def091999-11-25 00:26:21 +1100791 extern char *optarg;
792 extern int optind;
Damien Miller37023962000-07-11 17:31:38 +1000793 int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
Damien Miller166fca82000-04-20 07:42:21 +1000794 pid_t pid;
Damien Miller34132e52000-01-14 15:45:46 +1100795 socklen_t fromlen;
Damien Miller34132e52000-01-14 15:45:46 +1100796 fd_set *fdset;
797 struct sockaddr_storage from;
Damien Miller95def091999-11-25 00:26:21 +1100798 const char *remote_ip;
799 int remote_port;
Damien Miller95def091999-11-25 00:26:21 +1100800 FILE *f;
Damien Miller34132e52000-01-14 15:45:46 +1100801 struct addrinfo *ai;
802 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
803 int listen_sock, maxfd;
Damien Miller37023962000-07-11 17:31:38 +1000804 int startup_p[2];
805 int startups = 0;
Ben Lindstromd0fca422001-03-26 13:44:06 +0000806 Key *key;
Darren Tucker3e33cec2003-10-02 16:12:36 +1000807 Authctxt *authctxt;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000808 int ret, key_used = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000809
Kevin Steves0ea1d9d2002-04-25 18:17:04 +0000810#ifdef HAVE_SECUREWARE
811 (void)set_auth_parameters(ac, av);
812#endif
Damien Miller59d3d5b2003-08-22 09:34:41 +1000813 __progname = ssh_get_progname(av[0]);
Damien Millerf9b625c2000-07-09 22:42:32 +1000814 init_rng();
815
Damien Millera8ed44b2003-01-10 09:53:12 +1100816 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
Damien Millerb8c656e2000-06-28 15:22:41 +1000817 saved_argc = ac;
Damien Miller04cb5362003-05-15 21:29:10 +1000818 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
Damien Millera8ed44b2003-01-10 09:53:12 +1100819 for (i = 0; i < ac; i++)
820 saved_argv[i] = xstrdup(av[i]);
Damien Miller04cb5362003-05-15 21:29:10 +1000821 saved_argv[i] = NULL;
Damien Millera8ed44b2003-01-10 09:53:12 +1100822
823#ifndef HAVE_SETPROCTITLE
824 /* Prepare for later setproctitle emulation */
825 compat_init_setproctitle(ac, av);
Damien Millerf2e3e9d2003-06-02 12:15:54 +1000826 av = saved_argv;
Damien Millera8ed44b2003-01-10 09:53:12 +1100827#endif
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000828
Damien Miller95def091999-11-25 00:26:21 +1100829 /* Initialize configuration options to their default values. */
830 initialize_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000831
Damien Miller95def091999-11-25 00:26:21 +1100832 /* Parse command-line arguments. */
Darren Tuckerfe0078a2003-07-19 19:52:28 +1000833 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqtQ46")) != -1) {
Damien Miller95def091999-11-25 00:26:21 +1100834 switch (opt) {
Damien Miller34132e52000-01-14 15:45:46 +1100835 case '4':
836 IPv4or6 = AF_INET;
837 break;
838 case '6':
839 IPv4or6 = AF_INET6;
840 break;
Damien Miller95def091999-11-25 00:26:21 +1100841 case 'f':
842 config_file_name = optarg;
843 break;
844 case 'd':
Darren Tuckere98dfa32003-07-19 19:54:31 +1000845 if (debug_flag == 0) {
Damien Millere4340be2000-09-16 13:29:08 +1100846 debug_flag = 1;
847 options.log_level = SYSLOG_LEVEL_DEBUG1;
Darren Tuckere98dfa32003-07-19 19:54:31 +1000848 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
Damien Millere4340be2000-09-16 13:29:08 +1100849 options.log_level++;
Damien Miller95def091999-11-25 00:26:21 +1100850 break;
Ben Lindstromc72745a2000-12-02 19:03:54 +0000851 case 'D':
852 no_daemon_flag = 1;
853 break;
Ben Lindstrom9fce9f02001-04-11 23:10:09 +0000854 case 'e':
855 log_stderr = 1;
856 break;
Damien Miller95def091999-11-25 00:26:21 +1100857 case 'i':
858 inetd_flag = 1;
859 break;
860 case 'Q':
Ben Lindstromd5390202001-01-29 08:07:43 +0000861 /* ignored */
Damien Miller95def091999-11-25 00:26:21 +1100862 break;
863 case 'q':
864 options.log_level = SYSLOG_LEVEL_QUIET;
865 break;
866 case 'b':
867 options.server_key_bits = atoi(optarg);
868 break;
869 case 'p':
Damien Miller34132e52000-01-14 15:45:46 +1100870 options.ports_from_cmdline = 1;
Damien Millere4340be2000-09-16 13:29:08 +1100871 if (options.num_ports >= MAX_PORTS) {
872 fprintf(stderr, "too many ports.\n");
873 exit(1);
874 }
Ben Lindstrom19066a12001-04-12 23:39:26 +0000875 options.ports[options.num_ports++] = a2port(optarg);
876 if (options.ports[options.num_ports-1] == 0) {
877 fprintf(stderr, "Bad port number.\n");
878 exit(1);
879 }
Damien Miller95def091999-11-25 00:26:21 +1100880 break;
881 case 'g':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000882 if ((options.login_grace_time = convtime(optarg)) == -1) {
883 fprintf(stderr, "Invalid login grace time.\n");
884 exit(1);
885 }
Damien Miller95def091999-11-25 00:26:21 +1100886 break;
887 case 'k':
Ben Lindstrom1bda4c82001-06-05 19:59:08 +0000888 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
889 fprintf(stderr, "Invalid key regeneration interval.\n");
890 exit(1);
891 }
Damien Miller95def091999-11-25 00:26:21 +1100892 break;
893 case 'h':
Damien Miller0bc1bd82000-11-13 22:57:25 +1100894 if (options.num_host_key_files >= MAX_HOSTKEYS) {
895 fprintf(stderr, "too many host keys.\n");
896 exit(1);
897 }
898 options.host_key_files[options.num_host_key_files++] = optarg;
Damien Miller95def091999-11-25 00:26:21 +1100899 break;
Ben Lindstrom794325a2001-08-06 21:09:07 +0000900 case 't':
901 test_flag = 1;
902 break;
Damien Miller942da032000-08-18 13:59:06 +1000903 case 'u':
904 utmp_len = atoi(optarg);
Ben Lindstrom41daec72002-07-23 21:15:13 +0000905 if (utmp_len > MAXHOSTNAMELEN) {
906 fprintf(stderr, "Invalid utmp length.\n");
907 exit(1);
908 }
Damien Miller942da032000-08-18 13:59:06 +1000909 break;
Ben Lindstromade03f62001-12-06 18:22:17 +0000910 case 'o':
Damien Miller9f0f5c62001-12-21 14:45:46 +1100911 if (process_server_config_line(&options, optarg,
Ben Lindstromade03f62001-12-06 18:22:17 +0000912 "command-line", 0) != 0)
Damien Miller9f0f5c62001-12-21 14:45:46 +1100913 exit(1);
Ben Lindstromade03f62001-12-06 18:22:17 +0000914 break;
Damien Miller95def091999-11-25 00:26:21 +1100915 case '?':
916 default:
Ben Lindstromade03f62001-12-06 18:22:17 +0000917 usage();
918 break;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000919 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000920 }
Ben Lindstrom425fb022001-03-29 00:31:20 +0000921 SSLeay_add_all_algorithms();
Ben Lindstrom908afed2001-10-03 17:34:59 +0000922 channel_set_af(IPv4or6);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000923
Damien Miller34132e52000-01-14 15:45:46 +1100924 /*
925 * Force logging to stderr until we have loaded the private host
926 * key (unless started from inetd)
927 */
Kevin Stevesec84dc12000-12-13 17:45:15 +0000928 log_init(__progname,
Damien Miller5aa5d782002-02-08 22:01:54 +1100929 options.log_level == SYSLOG_LEVEL_NOT_SET ?
930 SYSLOG_LEVEL_INFO : options.log_level,
931 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
932 SYSLOG_FACILITY_AUTH : options.log_facility,
Ben Lindstromc2faa4a2002-11-09 15:50:03 +0000933 log_stderr || !inetd_flag);
Damien Miller34132e52000-01-14 15:45:46 +1100934
Tim Rice81ed5182002-09-25 17:38:46 -0700935#ifdef _UNICOS
Ben Lindstrom6db66ff2001-08-06 23:29:16 +0000936 /* Cray can define user privs drop all prives now!
937 * Not needed on PRIV_SU systems!
938 */
939 drop_cray_privs();
940#endif
941
Damien Miller60bc5172001-03-19 09:38:15 +1100942 seed_rng();
943
Damien Miller95def091999-11-25 00:26:21 +1100944 /* Read server configuration options from the configuration file. */
945 read_server_config(&options, config_file_name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000946
Damien Miller95def091999-11-25 00:26:21 +1100947 /* Fill in default values for those options not explicitly set. */
948 fill_default_server_options(&options);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000949
Damien Miller95def091999-11-25 00:26:21 +1100950 /* Check that there are no remaining arguments. */
951 if (optind < ac) {
952 fprintf(stderr, "Extra argument %s.\n", av[optind]);
953 exit(1);
954 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000955
Damien Miller95def091999-11-25 00:26:21 +1100956 debug("sshd version %.100s", SSH_VERSION);
Damien Miller2ccf6611999-11-15 15:25:10 +1100957
Damien Miller0bc1bd82000-11-13 22:57:25 +1100958 /* load private host keys */
Ben Lindstroma962c2f2002-07-04 00:14:17 +0000959 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
960 sizeof(Key *));
Damien Miller9f0f5c62001-12-21 14:45:46 +1100961 for (i = 0; i < options.num_host_key_files; i++)
Ben Lindstrom46c16222000-12-22 01:43:59 +0000962 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100963 sensitive_data.server_key = NULL;
964 sensitive_data.ssh1_host_key = NULL;
965 sensitive_data.have_ssh1_key = 0;
966 sensitive_data.have_ssh2_key = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000967
Damien Miller9f0f5c62001-12-21 14:45:46 +1100968 for (i = 0; i < options.num_host_key_files; i++) {
Ben Lindstromd0fca422001-03-26 13:44:06 +0000969 key = key_load_private(options.host_key_files[i], "", NULL);
970 sensitive_data.host_keys[i] = key;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100971 if (key == NULL) {
Ben Lindstrom15f33862001-04-16 02:00:02 +0000972 error("Could not load host key: %s",
973 options.host_key_files[i]);
Ben Lindstromd0fca422001-03-26 13:44:06 +0000974 sensitive_data.host_keys[i] = NULL;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100975 continue;
976 }
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000977 switch (key->type) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100978 case KEY_RSA1:
979 sensitive_data.ssh1_host_key = key;
980 sensitive_data.have_ssh1_key = 1;
981 break;
982 case KEY_RSA:
983 case KEY_DSA:
984 sensitive_data.have_ssh2_key = 1;
985 break;
986 }
Ben Lindstromd0fca422001-03-26 13:44:06 +0000987 debug("private host key: #%d type %d %s", i, key->type,
988 key_type(key));
Damien Miller0bc1bd82000-11-13 22:57:25 +1100989 }
990 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
Damien Miller996acd22003-04-09 20:59:48 +1000991 logit("Disabling protocol version 1. Could not load host key");
Damien Millereba71ba2000-04-29 23:57:08 +1000992 options.protocol &= ~SSH_PROTO_1;
993 }
Damien Miller0bc1bd82000-11-13 22:57:25 +1100994 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
Damien Miller996acd22003-04-09 20:59:48 +1000995 logit("Disabling protocol version 2. Could not load host key");
Damien Miller0bc1bd82000-11-13 22:57:25 +1100996 options.protocol &= ~SSH_PROTO_2;
Damien Millereba71ba2000-04-29 23:57:08 +1000997 }
Kevin Stevesadf74cd2001-02-05 14:22:50 +0000998 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
Damien Miller996acd22003-04-09 20:59:48 +1000999 logit("sshd: no hostkeys available -- exiting.");
Damien Miller95def091999-11-25 00:26:21 +11001000 exit(1);
1001 }
Damien Miller95def091999-11-25 00:26:21 +11001002
Damien Millereba71ba2000-04-29 23:57:08 +10001003 /* Check certain values for sanity. */
1004 if (options.protocol & SSH_PROTO_1) {
1005 if (options.server_key_bits < 512 ||
1006 options.server_key_bits > 32768) {
1007 fprintf(stderr, "Bad server key size.\n");
1008 exit(1);
1009 }
1010 /*
1011 * Check that server and host key lengths differ sufficiently. This
1012 * is necessary to make double encryption work with rsaref. Oh, I
1013 * hate software patents. I dont know if this can go? Niels
1014 */
1015 if (options.server_key_bits >
Ben Lindstrom822b6342002-06-23 21:38:49 +00001016 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1017 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1018 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1019 SSH_KEY_BITS_RESERVED) {
Damien Millereba71ba2000-04-29 23:57:08 +10001020 options.server_key_bits =
Ben Lindstrom822b6342002-06-23 21:38:49 +00001021 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1022 SSH_KEY_BITS_RESERVED;
Damien Millereba71ba2000-04-29 23:57:08 +10001023 debug("Forcing server key to %d bits to make it differ from host key.",
1024 options.server_key_bits);
1025 }
1026 }
1027
Ben Lindstroma26ea632002-06-06 20:46:25 +00001028 if (use_privsep) {
1029 struct passwd *pw;
1030 struct stat st;
1031
1032 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1033 fatal("Privilege separation user %s does not exist",
1034 SSH_PRIVSEP_USER);
1035 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1036 (S_ISDIR(st.st_mode) == 0))
1037 fatal("Missing privilege separation directory: %s",
1038 _PATH_PRIVSEP_CHROOT_DIR);
Ben Lindstrom59627352002-06-27 18:02:21 +00001039
1040#ifdef HAVE_CYGWIN
1041 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1042 (st.st_uid != getuid () ||
1043 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1044#else
Ben Lindstrom2dfacb32002-06-23 00:33:47 +00001045 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
Ben Lindstrom59627352002-06-27 18:02:21 +00001046#endif
Damien Miller180fc5b2003-02-24 11:50:18 +11001047 fatal("%s must be owned by root and not group or "
1048 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
Ben Lindstroma26ea632002-06-06 20:46:25 +00001049 }
1050
Ben Lindstrom794325a2001-08-06 21:09:07 +00001051 /* Configuration looks good, so exit if in test mode. */
1052 if (test_flag)
1053 exit(0);
1054
Damien Miller87aea252002-05-10 12:20:24 +10001055 /*
1056 * Clear out any supplemental groups we may have inherited. This
1057 * prevents inadvertent creation of files with bad modes (in the
Damien Millera8e06ce2003-11-21 23:48:55 +11001058 * portable version at least, it's certainly possible for PAM
1059 * to create a file, and we can't control the code in every
Damien Miller87aea252002-05-10 12:20:24 +10001060 * module which might be used).
1061 */
1062 if (setgroups(0, NULL) < 0)
1063 debug("setgroups() failed: %.200s", strerror(errno));
1064
Damien Millereba71ba2000-04-29 23:57:08 +10001065 /* Initialize the log (it is reinitialized below in case we forked). */
Damien Miller95def091999-11-25 00:26:21 +11001066 if (debug_flag && !inetd_flag)
1067 log_stderr = 1;
Kevin Stevesec84dc12000-12-13 17:45:15 +00001068 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +11001069
Damien Millereba71ba2000-04-29 23:57:08 +10001070 /*
1071 * If not in debugging mode, and not started from inetd, disconnect
1072 * from the controlling terminal, and fork. The original process
1073 * exits.
1074 */
Ben Lindstromc72745a2000-12-02 19:03:54 +00001075 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
Damien Miller95def091999-11-25 00:26:21 +11001076#ifdef TIOCNOTTY
1077 int fd;
1078#endif /* TIOCNOTTY */
1079 if (daemon(0, 0) < 0)
1080 fatal("daemon() failed: %.200s", strerror(errno));
1081
1082 /* Disconnect from the controlling tty. */
1083#ifdef TIOCNOTTY
Ben Lindstrom31ca54a2001-02-09 02:11:24 +00001084 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
Damien Miller95def091999-11-25 00:26:21 +11001085 if (fd >= 0) {
1086 (void) ioctl(fd, TIOCNOTTY, NULL);
1087 close(fd);
1088 }
1089#endif /* TIOCNOTTY */
1090 }
1091 /* Reinitialize the log (because of the fork above). */
Kevin Stevesec84dc12000-12-13 17:45:15 +00001092 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller95def091999-11-25 00:26:21 +11001093
Damien Miller95def091999-11-25 00:26:21 +11001094 /* Initialize the random number generator. */
1095 arc4random_stir();
1096
1097 /* Chdir to the root directory so that the current disk can be
1098 unmounted if desired. */
1099 chdir("/");
Damien Miller9f0f5c62001-12-21 14:45:46 +11001100
Ben Lindstromde71cda2001-03-24 00:43:26 +00001101 /* ignore SIGPIPE */
1102 signal(SIGPIPE, SIG_IGN);
Damien Miller95def091999-11-25 00:26:21 +11001103
Damien Miller95def091999-11-25 00:26:21 +11001104 /* Start listening for a socket, unless started from inetd. */
1105 if (inetd_flag) {
Ben Lindstrom206941f2001-04-15 14:27:16 +00001106 int s1;
Damien Miller95def091999-11-25 00:26:21 +11001107 s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
Ben Lindstrom206941f2001-04-15 14:27:16 +00001108 dup(s1);
Damien Miller95def091999-11-25 00:26:21 +11001109 sock_in = dup(0);
1110 sock_out = dup(1);
Damien Miller994cf142000-07-21 10:19:44 +10001111 startup_pipe = -1;
Damien Millereba71ba2000-04-29 23:57:08 +10001112 /*
1113 * We intentionally do not close the descriptors 0, 1, and 2
1114 * as our code for setting the descriptors won\'t work if
1115 * ttyfd happens to be one of those.
1116 */
Damien Miller95def091999-11-25 00:26:21 +11001117 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
Damien Miller0bc1bd82000-11-13 22:57:25 +11001118 if (options.protocol & SSH_PROTO_1)
Ben Lindstromca42d5f2001-03-09 18:25:32 +00001119 generate_ephemeral_server_key();
Damien Miller95def091999-11-25 00:26:21 +11001120 } else {
Damien Miller34132e52000-01-14 15:45:46 +11001121 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1122 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1123 continue;
1124 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1125 fatal("Too many listen sockets. "
1126 "Enlarge MAX_LISTEN_SOCKS");
1127 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1128 ntop, sizeof(ntop), strport, sizeof(strport),
1129 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1130 error("getnameinfo failed");
1131 continue;
1132 }
1133 /* Create socket for listening. */
Damien Miller2372ace2003-05-14 13:42:23 +10001134 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1135 ai->ai_protocol);
Damien Miller34132e52000-01-14 15:45:46 +11001136 if (listen_sock < 0) {
1137 /* kernel may not support ipv6 */
1138 verbose("socket: %.100s", strerror(errno));
1139 continue;
1140 }
Damien Miller34132e52000-01-14 15:45:46 +11001141 /*
Damien Millere1383ce2002-09-19 11:49:37 +10001142 * Set socket options.
1143 * Allow local port reuse in TIME_WAIT.
Damien Miller34132e52000-01-14 15:45:46 +11001144 */
Damien Millere1383ce2002-09-19 11:49:37 +10001145 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1146 &on, sizeof(on)) == -1)
1147 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +11001148
Damien Miller34132e52000-01-14 15:45:46 +11001149 debug("Bind to port %s on %s.", strport, ntop);
Damien Miller95def091999-11-25 00:26:21 +11001150
Damien Miller34132e52000-01-14 15:45:46 +11001151 /* Bind the socket to the desired port. */
Damien Miller0a4e27d2001-02-18 12:36:39 +11001152 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1153 if (!ai->ai_next)
1154 error("Bind to port %s on %s failed: %.200s.",
1155 strport, ntop, strerror(errno));
Damien Miller34132e52000-01-14 15:45:46 +11001156 close(listen_sock);
1157 continue;
1158 }
1159 listen_socks[num_listen_socks] = listen_sock;
1160 num_listen_socks++;
Damien Miller95def091999-11-25 00:26:21 +11001161
Damien Miller34132e52000-01-14 15:45:46 +11001162 /* Start listening on the port. */
Damien Miller996acd22003-04-09 20:59:48 +10001163 logit("Server listening on %s port %s.", ntop, strport);
Darren Tucker3175eb92003-12-09 19:15:11 +11001164 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
Damien Miller34132e52000-01-14 15:45:46 +11001165 fatal("listen: %.100s", strerror(errno));
1166
Damien Miller95def091999-11-25 00:26:21 +11001167 }
Damien Miller34132e52000-01-14 15:45:46 +11001168 freeaddrinfo(options.listen_addrs);
1169
1170 if (!num_listen_socks)
1171 fatal("Cannot bind any address.");
1172
Ben Lindstrom98097862001-06-25 05:10:20 +00001173 if (options.protocol & SSH_PROTO_1)
1174 generate_ephemeral_server_key();
1175
1176 /*
1177 * Arrange to restart on SIGHUP. The handler needs
1178 * listen_sock.
1179 */
1180 signal(SIGHUP, sighup_handler);
1181
1182 signal(SIGTERM, sigterm_handler);
1183 signal(SIGQUIT, sigterm_handler);
1184
1185 /* Arrange SIGCHLD to be caught. */
1186 signal(SIGCHLD, main_sigchld_handler);
1187
1188 /* Write out the pid file after the sigterm handler is setup */
Damien Miller95def091999-11-25 00:26:21 +11001189 if (!debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +11001190 /*
Ben Lindstrom7ad97102000-12-06 01:42:49 +00001191 * Record our pid in /var/run/sshd.pid to make it
1192 * easier to kill the correct sshd. We don't want to
1193 * do this before the bind above because the bind will
Damien Miller5428f641999-11-25 11:54:57 +11001194 * fail if there already is a daemon, and this will
1195 * overwrite any old pid in the file.
1196 */
Damien Millerbac2d8a2000-09-05 16:13:06 +11001197 f = fopen(options.pid_file, "wb");
Darren Tuckere5327042003-07-03 13:40:44 +10001198 if (f == NULL) {
1199 error("Couldn't create pid file \"%s\": %s",
1200 options.pid_file, strerror(errno));
1201 } else {
Ben Lindstromce0f6342002-06-11 16:42:49 +00001202 fprintf(f, "%ld\n", (long) getpid());
Damien Miller95def091999-11-25 00:26:21 +11001203 fclose(f);
1204 }
1205 }
Damien Miller95def091999-11-25 00:26:21 +11001206
Damien Miller34132e52000-01-14 15:45:46 +11001207 /* setup fd set for listen */
Damien Miller37023962000-07-11 17:31:38 +10001208 fdset = NULL;
Damien Miller34132e52000-01-14 15:45:46 +11001209 maxfd = 0;
1210 for (i = 0; i < num_listen_socks; i++)
1211 if (listen_socks[i] > maxfd)
1212 maxfd = listen_socks[i];
Damien Miller37023962000-07-11 17:31:38 +10001213 /* pipes connected to unauthenticated childs */
1214 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1215 for (i = 0; i < options.max_startups; i++)
1216 startup_pipes[i] = -1;
Damien Miller34132e52000-01-14 15:45:46 +11001217
Damien Miller5428f641999-11-25 11:54:57 +11001218 /*
1219 * Stay listening for connections until the system crashes or
1220 * the daemon is killed with a signal.
1221 */
Damien Miller95def091999-11-25 00:26:21 +11001222 for (;;) {
1223 if (received_sighup)
1224 sighup_restart();
Damien Miller37023962000-07-11 17:31:38 +10001225 if (fdset != NULL)
1226 xfree(fdset);
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001227 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
Damien Miller37023962000-07-11 17:31:38 +10001228 fdset = (fd_set *)xmalloc(fdsetsz);
Damien Miller34132e52000-01-14 15:45:46 +11001229 memset(fdset, 0, fdsetsz);
Damien Miller37023962000-07-11 17:31:38 +10001230
Damien Miller34132e52000-01-14 15:45:46 +11001231 for (i = 0; i < num_listen_socks; i++)
1232 FD_SET(listen_socks[i], fdset);
Damien Miller37023962000-07-11 17:31:38 +10001233 for (i = 0; i < options.max_startups; i++)
1234 if (startup_pipes[i] != -1)
1235 FD_SET(startup_pipes[i], fdset);
1236
1237 /* Wait in select until there is a connection. */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001238 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1239 if (ret < 0 && errno != EINTR)
1240 error("select: %.100s", strerror(errno));
Ben Lindstromec46e0b2001-06-09 01:27:31 +00001241 if (received_sigterm) {
Damien Miller996acd22003-04-09 20:59:48 +10001242 logit("Received signal %d; terminating.",
Ben Lindstromf8f065b2001-12-06 17:52:16 +00001243 (int) received_sigterm);
Ben Lindstromec46e0b2001-06-09 01:27:31 +00001244 close_listen_socks();
1245 unlink(options.pid_file);
1246 exit(255);
1247 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001248 if (key_used && key_do_regen) {
Ben Lindstromca42d5f2001-03-09 18:25:32 +00001249 generate_ephemeral_server_key();
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001250 key_used = 0;
1251 key_do_regen = 0;
Damien Miller34132e52000-01-14 15:45:46 +11001252 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001253 if (ret < 0)
1254 continue;
1255
Damien Miller37023962000-07-11 17:31:38 +10001256 for (i = 0; i < options.max_startups; i++)
1257 if (startup_pipes[i] != -1 &&
1258 FD_ISSET(startup_pipes[i], fdset)) {
1259 /*
1260 * the read end of the pipe is ready
1261 * if the child has closed the pipe
Ben Lindstrom4dccfa52000-12-28 16:40:05 +00001262 * after successful authentication
Damien Miller37023962000-07-11 17:31:38 +10001263 * or if the child has died
1264 */
1265 close(startup_pipes[i]);
1266 startup_pipes[i] = -1;
1267 startups--;
1268 }
Damien Miller34132e52000-01-14 15:45:46 +11001269 for (i = 0; i < num_listen_socks; i++) {
1270 if (!FD_ISSET(listen_socks[i], fdset))
Damien Miller95def091999-11-25 00:26:21 +11001271 continue;
Damien Miller37023962000-07-11 17:31:38 +10001272 fromlen = sizeof(from);
1273 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1274 &fromlen);
1275 if (newsock < 0) {
1276 if (errno != EINTR && errno != EWOULDBLOCK)
1277 error("accept: %.100s", strerror(errno));
1278 continue;
1279 }
Damien Miller942da032000-08-18 13:59:06 +10001280 if (drop_connection(startups) == 1) {
1281 debug("drop connection #%d", startups);
Damien Miller37023962000-07-11 17:31:38 +10001282 close(newsock);
1283 continue;
1284 }
1285 if (pipe(startup_p) == -1) {
1286 close(newsock);
1287 continue;
1288 }
1289
1290 for (j = 0; j < options.max_startups; j++)
1291 if (startup_pipes[j] == -1) {
1292 startup_pipes[j] = startup_p[0];
1293 if (maxfd < startup_p[0])
1294 maxfd = startup_p[0];
1295 startups++;
1296 break;
1297 }
Kevin Stevesef4eea92001-02-05 12:42:17 +00001298
Damien Miller5428f641999-11-25 11:54:57 +11001299 /*
Damien Miller37023962000-07-11 17:31:38 +10001300 * Got connection. Fork a child to handle it, unless
1301 * we are in debugging mode.
Damien Miller5428f641999-11-25 11:54:57 +11001302 */
Damien Miller37023962000-07-11 17:31:38 +10001303 if (debug_flag) {
Damien Miller5428f641999-11-25 11:54:57 +11001304 /*
Damien Miller37023962000-07-11 17:31:38 +10001305 * In debugging mode. Close the listening
1306 * socket, and start processing the
1307 * connection without forking.
Damien Miller5428f641999-11-25 11:54:57 +11001308 */
Damien Miller37023962000-07-11 17:31:38 +10001309 debug("Server will not fork when running in debugging mode.");
Damien Miller34132e52000-01-14 15:45:46 +11001310 close_listen_socks();
Damien Miller95def091999-11-25 00:26:21 +11001311 sock_in = newsock;
1312 sock_out = newsock;
Damien Miller4d97ba22000-07-11 18:15:50 +10001313 startup_pipe = -1;
Damien Miller182ee6e2000-07-12 09:45:27 +10001314 pid = getpid();
Damien Miller95def091999-11-25 00:26:21 +11001315 break;
Damien Miller37023962000-07-11 17:31:38 +10001316 } else {
1317 /*
1318 * Normal production daemon. Fork, and have
1319 * the child process the connection. The
1320 * parent continues listening.
1321 */
1322 if ((pid = fork()) == 0) {
1323 /*
1324 * Child. Close the listening and max_startup
1325 * sockets. Start using the accepted socket.
1326 * Reinitialize logging (since our pid has
1327 * changed). We break out of the loop to handle
1328 * the connection.
1329 */
1330 startup_pipe = startup_p[1];
Ben Lindstromd84df982001-12-06 16:35:40 +00001331 close_startup_pipes();
Damien Miller37023962000-07-11 17:31:38 +10001332 close_listen_socks();
1333 sock_in = newsock;
1334 sock_out = newsock;
Kevin Stevesec84dc12000-12-13 17:45:15 +00001335 log_init(__progname, options.log_level, options.log_facility, log_stderr);
Damien Miller37023962000-07-11 17:31:38 +10001336 break;
1337 }
Damien Miller95def091999-11-25 00:26:21 +11001338 }
Damien Miller37023962000-07-11 17:31:38 +10001339
1340 /* Parent. Stay in the loop. */
1341 if (pid < 0)
1342 error("fork: %.100s", strerror(errno));
1343 else
Ben Lindstromce0f6342002-06-11 16:42:49 +00001344 debug("Forked child %ld.", (long)pid);
Damien Miller37023962000-07-11 17:31:38 +10001345
1346 close(startup_p[1]);
1347
1348 /* Mark that the key has been used (it was "given" to the child). */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001349 if ((options.protocol & SSH_PROTO_1) &&
1350 key_used == 0) {
1351 /* Schedule server key regeneration alarm. */
Ben Lindstrom5ade9ab2003-08-25 01:16:21 +00001352 signal(SIGALRM, key_regeneration_alarm);
Ben Lindstromdb65e8f2001-01-19 04:26:52 +00001353 alarm(options.key_regeneration_time);
1354 key_used = 1;
1355 }
Damien Miller37023962000-07-11 17:31:38 +10001356
1357 arc4random_stir();
1358
1359 /* Close the new socket (the child is now taking care of it). */
1360 close(newsock);
Damien Miller95def091999-11-25 00:26:21 +11001361 }
Damien Miller34132e52000-01-14 15:45:46 +11001362 /* child process check (or debug mode) */
1363 if (num_listen_socks < 0)
1364 break;
Damien Miller95def091999-11-25 00:26:21 +11001365 }
1366 }
1367
1368 /* This is the child processing a new connection. */
1369
Damien Miller5428f641999-11-25 11:54:57 +11001370 /*
Ben Lindstrom17401b62002-05-15 16:17:56 +00001371 * Create a new session and process group since the 4.4BSD
1372 * setlogin() affects the entire process group. We don't
1373 * want the child to be able to affect the parent.
1374 */
Darren Tuckerc437cda2003-05-10 17:05:46 +10001375#if !defined(SSHD_ACQUIRES_CTTY)
Damien Miller933cc8f2003-03-10 11:38:10 +11001376 /*
Darren Tuckerc437cda2003-05-10 17:05:46 +10001377 * If setsid is called, on some platforms sshd will later acquire a
1378 * controlling terminal which will result in "could not set
1379 * controlling tty" errors.
Damien Miller933cc8f2003-03-10 11:38:10 +11001380 */
Ben Lindstrom57f08002002-06-23 00:37:10 +00001381 if (!debug_flag && !inetd_flag && setsid() < 0)
Ben Lindstrom17401b62002-05-15 16:17:56 +00001382 error("setsid: %.100s", strerror(errno));
Kevin Stevesc5041ac2002-05-21 17:50:21 +00001383#endif
Ben Lindstrom17401b62002-05-15 16:17:56 +00001384
1385 /*
Damien Miller5428f641999-11-25 11:54:57 +11001386 * Disable the key regeneration alarm. We will not regenerate the
1387 * key since we are no longer in a position to give it to anyone. We
1388 * will not restart on SIGHUP since it no longer makes sense.
1389 */
Damien Miller95def091999-11-25 00:26:21 +11001390 alarm(0);
1391 signal(SIGALRM, SIG_DFL);
1392 signal(SIGHUP, SIG_DFL);
1393 signal(SIGTERM, SIG_DFL);
1394 signal(SIGQUIT, SIG_DFL);
1395 signal(SIGCHLD, SIG_DFL);
Damien Miller4e0f5e12000-08-29 11:05:50 +11001396 signal(SIGINT, SIG_DFL);
Damien Miller95def091999-11-25 00:26:21 +11001397
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001398 /* Set keepalives if requested. */
1399 if (options.keepalives &&
Ben Lindstrom733a2352002-03-05 01:31:28 +00001400 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
Ben Lindstrombf555ba2001-01-18 02:04:35 +00001401 sizeof(on)) < 0)
1402 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1403
Damien Miller5428f641999-11-25 11:54:57 +11001404 /*
1405 * Register our connection. This turns encryption off because we do
1406 * not have a key.
1407 */
Damien Miller95def091999-11-25 00:26:21 +11001408 packet_set_connection(sock_in, sock_out);
1409
1410 remote_port = get_remote_port();
1411 remote_ip = get_remote_ipaddr();
1412
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001413#ifdef LIBWRAP
Damien Miller6a4a4b92001-11-12 11:07:11 +11001414 /* Check whether logins are denied from this host. */
Damien Miller95def091999-11-25 00:26:21 +11001415 {
1416 struct request_info req;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001417
Ben Lindstromce89dac2001-09-12 16:58:04 +00001418 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
Damien Miller95def091999-11-25 00:26:21 +11001419 fromhost(&req);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001420
Damien Miller95def091999-11-25 00:26:21 +11001421 if (!hosts_access(&req)) {
Damien Miller6a4a4b92001-11-12 11:07:11 +11001422 debug("Connection refused by tcp wrapper");
Ben Lindstrom7de696e2001-03-29 00:45:12 +00001423 refuse(&req);
Damien Miller6a4a4b92001-11-12 11:07:11 +11001424 /* NOTREACHED */
1425 fatal("libwrap refuse returns");
Damien Miller95def091999-11-25 00:26:21 +11001426 }
Damien Miller95def091999-11-25 00:26:21 +11001427 }
Damien Miller34132e52000-01-14 15:45:46 +11001428#endif /* LIBWRAP */
Damien Miller6a4a4b92001-11-12 11:07:11 +11001429
Damien Miller95def091999-11-25 00:26:21 +11001430 /* Log the connection. */
1431 verbose("Connection from %.500s port %d", remote_ip, remote_port);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001432
Damien Miller5428f641999-11-25 11:54:57 +11001433 /*
1434 * We don\'t want to listen forever unless the other side
1435 * successfully authenticates itself. So we set up an alarm which is
1436 * cleared after successful authentication. A limit of zero
1437 * indicates no limit. Note that we don\'t set the alarm in debugging
1438 * mode; it is just annoying to have the server exit just when you
1439 * are about to discover the bug.
1440 */
Ben Lindstrom5ade9ab2003-08-25 01:16:21 +00001441 signal(SIGALRM, grace_alarm_handler);
Damien Miller95def091999-11-25 00:26:21 +11001442 if (!debug_flag)
1443 alarm(options.login_grace_time);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001444
Damien Millerb38eff82000-04-01 11:09:21 +10001445 sshd_exchange_identification(sock_in, sock_out);
Darren Tuckerec960f22003-08-13 20:37:05 +10001446
Damien Miller95def091999-11-25 00:26:21 +11001447 packet_set_nonblocking();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001448
Damien Millera8e06ce2003-11-21 23:48:55 +11001449 /* prepare buffers to collect authentication messages */
Darren Tuckerb9aa0a02003-07-08 22:59:59 +10001450 buffer_init(&loginmsg);
1451
Darren Tucker3e33cec2003-10-02 16:12:36 +10001452 /* allocate authentication context */
1453 authctxt = xmalloc(sizeof(*authctxt));
1454 memset(authctxt, 0, sizeof(*authctxt));
1455
1456 /* XXX global for cleanup, access from other modules */
1457 the_authctxt = authctxt;
1458
Ben Lindstrom943481c2002-03-22 03:43:46 +00001459 if (use_privsep)
Darren Tucker3e33cec2003-10-02 16:12:36 +10001460 if (privsep_preauth(authctxt) == 1)
Ben Lindstrom943481c2002-03-22 03:43:46 +00001461 goto authenticated;
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001462
Damien Miller396691a2000-01-20 22:44:08 +11001463 /* perform the key exchange */
Damien Miller396691a2000-01-20 22:44:08 +11001464 /* authenticate user and start session */
Damien Millerefb4afe2000-04-12 18:45:05 +10001465 if (compat20) {
1466 do_ssh2_kex();
Darren Tucker3e33cec2003-10-02 16:12:36 +10001467 do_authentication2(authctxt);
Damien Millerefb4afe2000-04-12 18:45:05 +10001468 } else {
1469 do_ssh1_kex();
Darren Tucker3e33cec2003-10-02 16:12:36 +10001470 do_authentication(authctxt);
Damien Millerefb4afe2000-04-12 18:45:05 +10001471 }
Ben Lindstrom943481c2002-03-22 03:43:46 +00001472 /*
1473 * If we use privilege separation, the unprivileged child transfers
1474 * the current keystate and exits
1475 */
1476 if (use_privsep) {
Ben Lindstrom7339b2a2002-05-15 16:25:01 +00001477 mm_send_keystate(pmonitor);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001478 exit(0);
Ben Lindstrom943481c2002-03-22 03:43:46 +00001479 }
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001480
1481 authenticated:
Ben Lindstrom6328ab32002-03-22 02:54:23 +00001482 /*
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001483 * In privilege separation, we fork another child and prepare
1484 * file descriptor passing.
1485 */
1486 if (use_privsep) {
Ben Lindstrom943481c2002-03-22 03:43:46 +00001487 privsep_postauth(authctxt);
1488 /* the monitor process [priv] will not return */
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001489 if (!compat20)
1490 destroy_sensitive_data();
1491 }
Ben Lindstrom73ab9ba2002-03-22 01:27:35 +00001492
Darren Tucker3e33cec2003-10-02 16:12:36 +10001493 /* Start session. */
Ben Lindstrom73ab9ba2002-03-22 01:27:35 +00001494 do_authenticated(authctxt);
1495
Damien Miller3a5b0232002-03-13 13:19:42 +11001496 /* The connection has been terminated. */
1497 verbose("Closing connection to %.100s", remote_ip);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001498
Damien Millerbeb4ba51999-12-28 15:09:35 +11001499#ifdef USE_PAM
Damien Miller4e448a32003-05-14 15:11:48 +10001500 if (options.use_pam)
1501 finish_pam();
Damien Millerbeb4ba51999-12-28 15:09:35 +11001502#endif /* USE_PAM */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001503
Damien Miller95def091999-11-25 00:26:21 +11001504 packet_close();
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001505
1506 if (use_privsep)
1507 mm_terminate();
1508
Damien Miller95def091999-11-25 00:26:21 +11001509 exit(0);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001510}
1511
Damien Miller95def091999-11-25 00:26:21 +11001512/*
Ben Lindstromabcb1452002-03-22 01:10:21 +00001513 * Decrypt session_key_int using our private server key and private host key
1514 * (key with larger modulus first).
1515 */
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001516int
Ben Lindstromabcb1452002-03-22 01:10:21 +00001517ssh1_session_key(BIGNUM *session_key_int)
1518{
1519 int rsafail = 0;
1520
1521 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1522 /* Server key has bigger modulus. */
1523 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1524 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1525 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1526 get_remote_ipaddr(),
1527 BN_num_bits(sensitive_data.server_key->rsa->n),
1528 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1529 SSH_KEY_BITS_RESERVED);
1530 }
1531 if (rsa_private_decrypt(session_key_int, session_key_int,
1532 sensitive_data.server_key->rsa) <= 0)
1533 rsafail++;
1534 if (rsa_private_decrypt(session_key_int, session_key_int,
1535 sensitive_data.ssh1_host_key->rsa) <= 0)
1536 rsafail++;
1537 } else {
1538 /* Host key has bigger modulus (or they are equal). */
1539 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1540 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1541 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1542 get_remote_ipaddr(),
1543 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1544 BN_num_bits(sensitive_data.server_key->rsa->n),
1545 SSH_KEY_BITS_RESERVED);
1546 }
1547 if (rsa_private_decrypt(session_key_int, session_key_int,
1548 sensitive_data.ssh1_host_key->rsa) < 0)
1549 rsafail++;
1550 if (rsa_private_decrypt(session_key_int, session_key_int,
1551 sensitive_data.server_key->rsa) < 0)
1552 rsafail++;
1553 }
1554 return (rsafail);
1555}
1556/*
Damien Miller396691a2000-01-20 22:44:08 +11001557 * SSH1 key exchange
Damien Miller95def091999-11-25 00:26:21 +11001558 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001559static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001560do_ssh1_kex(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001561{
Damien Miller95def091999-11-25 00:26:21 +11001562 int i, len;
Damien Miller7650bc62001-01-30 09:27:26 +11001563 int rsafail = 0;
Damien Miller95def091999-11-25 00:26:21 +11001564 BIGNUM *session_key_int;
Ben Lindstrom46c16222000-12-22 01:43:59 +00001565 u_char session_key[SSH_SESSION_KEY_LENGTH];
1566 u_char cookie[8];
1567 u_int cipher_type, auth_mask, protocol_flags;
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +00001568 u_int32_t rnd = 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001569
Damien Miller5428f641999-11-25 11:54:57 +11001570 /*
1571 * Generate check bytes that the client must send back in the user
1572 * packet in order for it to be accepted; this is used to defy ip
1573 * spoofing attacks. Note that this only works against somebody
1574 * doing IP spoofing from a remote machine; any machine on the local
1575 * network can still see outgoing packets and catch the random
1576 * cookie. This only affects rhosts authentication, and this is one
1577 * of the reasons why it is inherently insecure.
1578 */
Damien Miller95def091999-11-25 00:26:21 +11001579 for (i = 0; i < 8; i++) {
1580 if (i % 4 == 0)
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +00001581 rnd = arc4random();
1582 cookie[i] = rnd & 0xff;
1583 rnd >>= 8;
Damien Miller95def091999-11-25 00:26:21 +11001584 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001585
Damien Miller5428f641999-11-25 11:54:57 +11001586 /*
1587 * Send our public key. We include in the packet 64 bits of random
1588 * data that must be matched in the reply in order to prevent IP
1589 * spoofing.
1590 */
Damien Miller95def091999-11-25 00:26:21 +11001591 packet_start(SSH_SMSG_PUBLIC_KEY);
1592 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001593 packet_put_char(cookie[i]);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001594
Damien Miller95def091999-11-25 00:26:21 +11001595 /* Store our public server RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001596 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1597 packet_put_bignum(sensitive_data.server_key->rsa->e);
1598 packet_put_bignum(sensitive_data.server_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001599
Damien Miller95def091999-11-25 00:26:21 +11001600 /* Store our public host RSA key. */
Damien Miller0bc1bd82000-11-13 22:57:25 +11001601 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1602 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1603 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001604
Damien Miller95def091999-11-25 00:26:21 +11001605 /* Put protocol flags. */
1606 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001607
Damien Miller95def091999-11-25 00:26:21 +11001608 /* Declare which ciphers we support. */
Damien Miller874d77b2000-10-14 16:23:11 +11001609 packet_put_int(cipher_mask_ssh1(0));
Damien Miller95def091999-11-25 00:26:21 +11001610
1611 /* Declare supported authentication types. */
1612 auth_mask = 0;
Damien Miller95def091999-11-25 00:26:21 +11001613 if (options.rhosts_rsa_authentication)
1614 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1615 if (options.rsa_authentication)
1616 auth_mask |= 1 << SSH_AUTH_RSA;
Ben Lindstrom551ea372001-06-05 18:56:16 +00001617 if (options.challenge_response_authentication == 1)
Damien Miller95def091999-11-25 00:26:21 +11001618 auth_mask |= 1 << SSH_AUTH_TIS;
Damien Miller95def091999-11-25 00:26:21 +11001619 if (options.password_authentication)
1620 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1621 packet_put_int(auth_mask);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001622
Damien Miller95def091999-11-25 00:26:21 +11001623 /* Send the packet and wait for it to be sent. */
1624 packet_send();
1625 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001626
Damien Miller0bc1bd82000-11-13 22:57:25 +11001627 debug("Sent %d bit server key and %d bit host key.",
1628 BN_num_bits(sensitive_data.server_key->rsa->n),
1629 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001630
Damien Miller95def091999-11-25 00:26:21 +11001631 /* Read clients reply (cipher type and session key). */
Damien Millerdff50992002-01-22 23:16:32 +11001632 packet_read_expect(SSH_CMSG_SESSION_KEY);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001633
Damien Miller50945fa1999-12-09 10:31:37 +11001634 /* Get cipher type and check whether we accept this. */
Damien Miller95def091999-11-25 00:26:21 +11001635 cipher_type = packet_get_char();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001636
Damien Miller874d77b2000-10-14 16:23:11 +11001637 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
Damien Miller50945fa1999-12-09 10:31:37 +11001638 packet_disconnect("Warning: client selects unsupported cipher.");
1639
Damien Miller95def091999-11-25 00:26:21 +11001640 /* Get check bytes from the packet. These must match those we
1641 sent earlier with the public key packet. */
1642 for (i = 0; i < 8; i++)
Damien Miller396691a2000-01-20 22:44:08 +11001643 if (cookie[i] != packet_get_char())
Damien Miller95def091999-11-25 00:26:21 +11001644 packet_disconnect("IP Spoofing check bytes do not match.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001645
Damien Miller95def091999-11-25 00:26:21 +11001646 debug("Encryption type: %.200s", cipher_name(cipher_type));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001647
Damien Miller95def091999-11-25 00:26:21 +11001648 /* Get the encrypted integer. */
Damien Millerda755162002-01-22 23:09:22 +11001649 if ((session_key_int = BN_new()) == NULL)
1650 fatal("do_ssh1_kex: BN_new failed");
Damien Millerd432ccf2002-01-22 23:14:44 +11001651 packet_get_bignum(session_key_int);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001652
Damien Miller95def091999-11-25 00:26:21 +11001653 protocol_flags = packet_get_int();
1654 packet_set_protocol_flags(protocol_flags);
Damien Miller48b03fc2002-01-22 23:11:40 +11001655 packet_check_eom();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001656
Ben Lindstromabcb1452002-03-22 01:10:21 +00001657 /* Decrypt session_key_int using host/server keys */
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001658 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1659
Damien Miller5428f641999-11-25 11:54:57 +11001660 /*
1661 * Extract session key from the decrypted integer. The key is in the
1662 * least significant 256 bits of the integer; the first byte of the
1663 * key is in the highest bits.
1664 */
Damien Miller7650bc62001-01-30 09:27:26 +11001665 if (!rsafail) {
1666 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1667 len = BN_num_bytes(session_key_int);
1668 if (len < 0 || len > sizeof(session_key)) {
1669 error("do_connection: bad session key len from %s: "
Ben Lindstrom31ca54a2001-02-09 02:11:24 +00001670 "session_key_int %d > sizeof(session_key) %lu",
1671 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
Damien Miller7650bc62001-01-30 09:27:26 +11001672 rsafail++;
1673 } else {
1674 memset(session_key, 0, sizeof(session_key));
1675 BN_bn2bin(session_key_int,
1676 session_key + sizeof(session_key) - len);
Ben Lindstromeb648a72001-03-05 06:00:29 +00001677
1678 compute_session_id(session_id, cookie,
1679 sensitive_data.ssh1_host_key->rsa->n,
1680 sensitive_data.server_key->rsa->n);
1681 /*
1682 * Xor the first 16 bytes of the session key with the
1683 * session id.
1684 */
1685 for (i = 0; i < 16; i++)
1686 session_key[i] ^= session_id[i];
Damien Miller7650bc62001-01-30 09:27:26 +11001687 }
1688 }
1689 if (rsafail) {
Ben Lindstromeb648a72001-03-05 06:00:29 +00001690 int bytes = BN_num_bytes(session_key_int);
Ben Lindstrom13c5d3b2002-02-26 18:00:48 +00001691 u_char *buf = xmalloc(bytes);
Ben Lindstromeb648a72001-03-05 06:00:29 +00001692 MD5_CTX md;
1693
Damien Miller996acd22003-04-09 20:59:48 +10001694 logit("do_connection: generating a fake encryption key");
Ben Lindstromeb648a72001-03-05 06:00:29 +00001695 BN_bn2bin(session_key_int, buf);
1696 MD5_Init(&md);
1697 MD5_Update(&md, buf, bytes);
1698 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1699 MD5_Final(session_key, &md);
1700 MD5_Init(&md);
1701 MD5_Update(&md, session_key, 16);
1702 MD5_Update(&md, buf, bytes);
1703 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1704 MD5_Final(session_key + 16, &md);
1705 memset(buf, 0, bytes);
1706 xfree(buf);
Ben Lindstrom941ac822001-03-05 06:25:23 +00001707 for (i = 0; i < 16; i++)
1708 session_id[i] = session_key[i] ^ session_key[i + 16];
Damien Miller7650bc62001-01-30 09:27:26 +11001709 }
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001710 /* Destroy the private and public keys. No longer. */
Damien Miller3a5b0232002-03-13 13:19:42 +11001711 destroy_sensitive_data();
Ben Lindstromeb648a72001-03-05 06:00:29 +00001712
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001713 if (use_privsep)
1714 mm_ssh1_session_id(session_id);
1715
Damien Miller396691a2000-01-20 22:44:08 +11001716 /* Destroy the decrypted integer. It is no longer needed. */
1717 BN_clear_free(session_key_int);
1718
Damien Miller95def091999-11-25 00:26:21 +11001719 /* Set the session key. From this on all communications will be encrypted. */
1720 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001721
Damien Miller95def091999-11-25 00:26:21 +11001722 /* Destroy our copy of the session key. It is no longer needed. */
1723 memset(session_key, 0, sizeof(session_key));
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001724
Damien Miller95def091999-11-25 00:26:21 +11001725 debug("Received session key; encryption turned on.");
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001726
Ben Lindstromf666fec2002-06-06 19:51:58 +00001727 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
Damien Miller95def091999-11-25 00:26:21 +11001728 packet_start(SSH_SMSG_SUCCESS);
1729 packet_send();
1730 packet_write_wait();
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001731}
Damien Millerefb4afe2000-04-12 18:45:05 +10001732
1733/*
1734 * SSH2 key exchange: diffie-hellman-group1-sha1
1735 */
Ben Lindstrombba81212001-06-25 05:01:22 +00001736static void
Ben Lindstrom46c16222000-12-22 01:43:59 +00001737do_ssh2_kex(void)
Damien Millerefb4afe2000-04-12 18:45:05 +10001738{
Damien Millerefb4afe2000-04-12 18:45:05 +10001739 Kex *kex;
Damien Millerefb4afe2000-04-12 18:45:05 +10001740
Damien Miller78928792000-04-12 20:17:38 +10001741 if (options.ciphers != NULL) {
Damien Miller4af51302000-04-16 11:18:38 +10001742 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
Damien Miller78928792000-04-12 20:17:38 +10001743 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1744 }
Damien Millera0ff4662001-03-30 10:49:35 +10001745 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1746 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1747 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1748 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1749
Ben Lindstrom06b33aa2001-02-15 03:01:59 +00001750 if (options.macs != NULL) {
1751 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1752 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1753 }
Ben Lindstrom23e0f662002-06-21 01:09:47 +00001754 if (!options.compression) {
1755 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1756 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1757 }
Damien Miller0bc1bd82000-11-13 22:57:25 +11001758 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1759
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001760 /* start key exchange */
Ben Lindstrom238abf62001-04-04 17:52:53 +00001761 kex = kex_setup(myproposal);
Damien Miller8e7fb332003-02-24 12:03:03 +11001762 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1763 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001764 kex->server = 1;
1765 kex->client_version_string=client_version_string;
1766 kex->server_version_string=server_version_string;
1767 kex->load_host_key=&get_hostkey_by_type;
Ben Lindstrom7a2073c2002-03-22 02:30:41 +00001768 kex->host_key_index=&get_hostkey_index;
Damien Millerefb4afe2000-04-12 18:45:05 +10001769
Ben Lindstrom8ac91062001-04-04 17:57:54 +00001770 xxx_kex = kex;
1771
Ben Lindstrombe2cc432001-04-04 23:46:07 +00001772 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
Damien Miller874d77b2000-10-14 16:23:11 +11001773
Ben Lindstrom2d90e002001-04-04 02:00:54 +00001774 session_id2 = kex->session_id;
1775 session_id2_len = kex->session_id_len;
1776
Damien Miller874d77b2000-10-14 16:23:11 +11001777#ifdef DEBUG_KEXDH
1778 /* send 1st encrypted/maced/compressed message */
1779 packet_start(SSH2_MSG_IGNORE);
1780 packet_put_cstring("markus");
1781 packet_send();
1782 packet_write_wait();
1783#endif
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +00001784 debug("KEX done");
Damien Millerefb4afe2000-04-12 18:45:05 +10001785}
Darren Tucker3e33cec2003-10-02 16:12:36 +10001786
1787/* server specific fatal cleanup */
1788void
1789cleanup_exit(int i)
1790{
1791 if (the_authctxt)
1792 do_cleanup(the_authctxt);
1793 _exit(i);
1794}