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- avsm@cvs.openbsd.org 2004/06/26 20:07:16
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8efc0c15 1/*
5260325f 2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
bcbf86ec 5 * This program is the ssh daemon. It listens for connections from clients,
6 * and performs authentication, executes use commands or shell, and forwards
5260325f 7 * information to/from the application to the user client over an encrypted
bcbf86ec 8 * connection. This can also handle forwarding of X11, TCP/IP, and
9 * authentication agent connections.
e78a59f5 10 *
bcbf86ec 11 * 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:
1853d1ef 18 * Privilege Separation:
bcbf86ec 19 *
1853d1ef 20 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
21 * Copyright (c) 2002 Niels Provos. All rights reserved.
bcbf86ec 22 *
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.
5260325f 42 */
8efc0c15 43
44#include "includes.h"
83529a6b 45RCSID("$OpenBSD: sshd.c,v 1.297 2004/06/26 20:07:16 avsm Exp $");
8efc0c15 46
42f11eb2 47#include <openssl/dh.h>
48#include <openssl/bn.h>
436c347c 49#include <openssl/md5.h>
1853d1ef 50#include <openssl/rand.h>
6e879cb4 51#ifdef HAVE_SECUREWARE
52#include <sys/security.h>
53#include <prot.h>
54#endif
42f11eb2 55
56#include "ssh.h"
57#include "ssh1.h"
58#include "ssh2.h"
8efc0c15 59#include "xmalloc.h"
60#include "rsa.h"
1729c161 61#include "sshpty.h"
8efc0c15 62#include "packet.h"
42f11eb2 63#include "log.h"
8efc0c15 64#include "servconf.h"
65#include "uidswap.h"
66#include "compat.h"
7368a6c8 67#include "buffer.h"
b9a549d7 68#include "bufaux.h"
42f11eb2 69#include "cipher.h"
e78a59f5 70#include "kex.h"
7368a6c8 71#include "key.h"
94ec8c6b 72#include "dh.h"
e78a59f5 73#include "myproposal.h"
a306f2dd 74#include "authfile.h"
42f11eb2 75#include "pathnames.h"
76#include "atomicio.h"
77#include "canohost.h"
78#include "auth.h"
79#include "misc.h"
b9a549d7 80#include "msg.h"
a5c9ffdb 81#include "dispatch.h"
e4d7f734 82#include "channels.h"
1b34c1b3 83#include "session.h"
1853d1ef 84#include "monitor_mm.h"
85#include "monitor.h"
86#include "monitor_wrap.h"
87#include "monitor_fdpass.h"
8efc0c15 88
89#ifdef LIBWRAP
90#include <tcpd.h>
91#include <syslog.h>
92int allow_severity = LOG_INFO;
93int deny_severity = LOG_WARNING;
94#endif /* LIBWRAP */
95
96#ifndef O_NOCTTY
97#define O_NOCTTY 0
98#endif
99
b250e837 100/* Re-exec fds */
101#define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
102#define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
103#define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
104#define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
105
260d427b 106#ifdef HAVE___PROGNAME
107extern char *__progname;
108#else
109char *__progname;
110#endif
111
8efc0c15 112/* Server configuration options. */
113ServerOptions options;
114
115/* Name of the server configuration file. */
42f11eb2 116char *config_file_name = _PATH_SERVER_CONFIG_FILE;
8efc0c15 117
6ae2364d 118/*
48e671d5 119 * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
120 * Default value is AF_UNSPEC means both IPv4 and IPv6.
121 */
122int IPv4or6 = AF_UNSPEC;
123
5260325f 124/*
125 * Debug mode flag. This can be set on the command line. If debug
126 * mode is enabled, extra debugging output will be sent to the system
127 * log, the daemon will not go to background, and will exit after processing
128 * the first connection.
129 */
8efc0c15 130int debug_flag = 0;
131
f87f09aa 132/* Flag indicating that the daemon should only test the configuration and keys. */
133int test_flag = 0;
134
8efc0c15 135/* Flag indicating that the daemon is being started from inetd. */
136int inetd_flag = 0;
137
0b6fbf03 138/* Flag indicating that sshd should not detach and become a daemon. */
139int no_daemon_flag = 0;
140
6a17f9c2 141/* debug goes to stderr unless inetd_flag is set */
142int log_stderr = 0;
143
8efc0c15 144/* Saved arguments to main(). */
145char **saved_argv;
4d33e531 146int saved_argc;
8efc0c15 147
b9a549d7 148/* re-exec */
149int rexeced_flag = 0;
150int rexec_flag = 1;
151int rexec_argc = 0;
152char **rexec_argv;
153
aa3378df 154/*
48e671d5 155 * The sockets that the server is listening; this is used in the SIGHUP
156 * signal handler.
aa3378df 157 */
48e671d5 158#define MAX_LISTEN_SOCKS 16
159int listen_socks[MAX_LISTEN_SOCKS];
160int num_listen_socks = 0;
8efc0c15 161
aa3378df 162/*
163 * the client's version string, passed by sshd2 in compat mode. if != NULL,
164 * sshd will skip the version-number exchange
165 */
5260325f 166char *client_version_string = NULL;
7368a6c8 167char *server_version_string = NULL;
8efc0c15 168
7a37c112 169/* for rekeying XXX fixme */
170Kex *xxx_kex;
171
aa3378df 172/*
173 * Any really sensitive data in the application is contained in this
174 * structure. The idea is that this structure could be locked into memory so
175 * that the pages do not get written into swap. However, there are some
176 * problems. The private key contains BIGNUMs, and we do not (in principle)
177 * have access to the internals of them, and locking just the structure is
178 * not very useful. Currently, memory locking is not implemented.
179 */
5260325f 180struct {
cb7bd922 181 Key *server_key; /* ephemeral server key */
fa08c86b 182 Key *ssh1_host_key; /* ssh1 host key */
183 Key **host_keys; /* all private host keys */
184 int have_ssh1_key;
185 int have_ssh2_key;
00be5382 186 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
8efc0c15 187} sensitive_data;
188
aa3378df 189/*
59c97189 190 * Flag indicating whether the RSA server key needs to be regenerated.
191 * Is set in the SIGALRM handler and cleared when the key is regenerated.
aa3378df 192 */
7a934d1b 193static volatile sig_atomic_t key_do_regen = 0;
8efc0c15 194
c9130033 195/* This is set to true when a signal is received. */
7a934d1b 196static volatile sig_atomic_t received_sighup = 0;
197static volatile sig_atomic_t received_sigterm = 0;
8efc0c15 198
7368a6c8 199/* session identifier, used by RSA-auth */
1e3b8b07 200u_char session_id[16];
e7c0f9d5 201
a306f2dd 202/* same for ssh2 */
1e3b8b07 203u_char *session_id2 = NULL;
a27002e5 204u_int session_id2_len = 0;
a306f2dd 205
c345cf9d 206/* record remote hostname or ip */
1e3b8b07 207u_int utmp_len = MAXHOSTNAMELEN;
c345cf9d 208
7ace8c3b 209/* options.max_startup sized array of fd ints */
210int *startup_pipes = NULL;
211int startup_pipe; /* in child */
212
1853d1ef 213/* variables used for privilege separation */
98a58eda 214int use_privsep;
a9b33b95 215struct monitor *pmonitor = NULL;
1853d1ef 216
bc7dfc06 217/* message to be displayed after login */
218Buffer loginmsg;
219
2362db19 220/* global authentication context */
221Authctxt *the_authctxt = NULL;
222
7368a6c8 223/* Prototypes for various functions defined later in this file. */
396c147e 224void destroy_sensitive_data(void);
1853d1ef 225void demote_sensitive_data(void);
c8d54615 226
396c147e 227static void do_ssh1_kex(void);
228static void do_ssh2_kex(void);
94ec8c6b 229
48e671d5 230/*
231 * Close all listening sockets
232 */
396c147e 233static void
48e671d5 234close_listen_socks(void)
235{
236 int i;
e424e241 237
48e671d5 238 for (i = 0; i < num_listen_socks; i++)
239 close(listen_socks[i]);
240 num_listen_socks = -1;
241}
242
7ace8c3b 243static void
244close_startup_pipes(void)
245{
246 int i;
e424e241 247
7ace8c3b 248 if (startup_pipes)
249 for (i = 0; i < options.max_startups; i++)
250 if (startup_pipes[i] != -1)
251 close(startup_pipes[i]);
252}
253
5260325f 254/*
255 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
256 * the effect is to reread the configuration file (and to regenerate
257 * the server key).
258 */
396c147e 259static void
5260325f 260sighup_handler(int sig)
8efc0c15 261{
6056eb35 262 int save_errno = errno;
263
5260325f 264 received_sighup = 1;
265 signal(SIGHUP, sighup_handler);
6056eb35 266 errno = save_errno;
8efc0c15 267}
268
5260325f 269/*
270 * Called from the main program after receiving SIGHUP.
271 * Restarts the server.
272 */
396c147e 273static void
5ca51e19 274sighup_restart(void)
8efc0c15 275{
bbe88b6d 276 logit("Received SIGHUP; restarting.");
48e671d5 277 close_listen_socks();
7ace8c3b 278 close_startup_pipes();
5260325f 279 execv(saved_argv[0], saved_argv);
bbe88b6d 280 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
e424e241 281 strerror(errno));
5260325f 282 exit(1);
8efc0c15 283}
284
5260325f 285/*
286 * Generic signal handler for terminating signals in the master daemon.
5260325f 287 */
396c147e 288static void
5260325f 289sigterm_handler(int sig)
8efc0c15 290{
c9130033 291 received_sigterm = sig;
8efc0c15 292}
293
5260325f 294/*
295 * SIGCHLD handler. This is called whenever a child dies. This will then
c9130033 296 * reap any zombies left by exited children.
5260325f 297 */
396c147e 298static void
5260325f 299main_sigchld_handler(int sig)
8efc0c15 300{
5260325f 301 int save_errno = errno;
e424e241 302 pid_t pid;
5260325f 303 int status;
5ad13cd7 304
8c38e88b 305 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
306 (pid < 0 && errno == EINTR))
5260325f 307 ;
5ad13cd7 308
5260325f 309 signal(SIGCHLD, main_sigchld_handler);
310 errno = save_errno;
8efc0c15 311}
312
5260325f 313/*
314 * Signal handler for the alarm after the login grace period has expired.
315 */
396c147e 316static void
5260325f 317grace_alarm_handler(int sig)
8efc0c15 318{
c9130033 319 /* XXX no idea how fix this signal handler */
320
a9b33b95 321 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
322 kill(pmonitor->m_pid, SIGALRM);
323
5260325f 324 /* Log error and exit. */
26b9a3d2 325 fatal("Timeout before authentication for %s", get_remote_ipaddr());
5260325f 326}
8efc0c15 327
5260325f 328/*
329 * Signal handler for the key regeneration alarm. Note that this
330 * alarm only occurs in the daemon waiting for connections, and it does not
331 * do anything with the private key or random state before forking.
332 * Thus there should be no concurrency control/asynchronous execution
333 * problems.
334 */
396c147e 335static void
cb7bd922 336generate_ephemeral_server_key(void)
fa08c86b 337{
7fdc56c5 338 u_int32_t rnd = 0;
00be5382 339 int i;
340
cd332296 341 verbose("Generating %s%d bit RSA key.",
76ca7b01 342 sensitive_data.server_key ? "new " : "", options.server_key_bits);
fa08c86b 343 if (sensitive_data.server_key != NULL)
344 key_free(sensitive_data.server_key);
cd332296 345 sensitive_data.server_key = key_generate(KEY_RSA1,
76ca7b01 346 options.server_key_bits);
347 verbose("RSA key generation complete.");
00be5382 348
349 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
350 if (i % 4 == 0)
7fdc56c5 351 rnd = arc4random();
352 sensitive_data.ssh1_cookie[i] = rnd & 0xff;
353 rnd >>= 8;
00be5382 354 }
355 arc4random_stir();
fa08c86b 356}
f546c780 357
396c147e 358static void
5260325f 359key_regeneration_alarm(int sig)
360{
361 int save_errno = errno;
e424e241 362
59c97189 363 signal(SIGALRM, SIG_DFL);
5260325f 364 errno = save_errno;
59c97189 365 key_do_regen = 1;
5260325f 366}
8efc0c15 367
396c147e 368static void
7368a6c8 369sshd_exchange_identification(int sock_in, int sock_out)
370{
a8be9f80 371 int i, mismatch;
7368a6c8 372 int remote_major, remote_minor;
a8be9f80 373 int major, minor;
7368a6c8 374 char *s;
375 char buf[256]; /* Must not be larger than remote_version. */
376 char remote_version[256]; /* Must be at least as big as buf. */
377
a8be9f80 378 if ((options.protocol & SSH_PROTO_1) &&
379 (options.protocol & SSH_PROTO_2)) {
380 major = PROTOCOL_MAJOR_1;
381 minor = 99;
382 } else if (options.protocol & SSH_PROTO_2) {
383 major = PROTOCOL_MAJOR_2;
384 minor = PROTOCOL_MINOR_2;
385 } else {
386 major = PROTOCOL_MAJOR_1;
387 minor = PROTOCOL_MINOR_1;
388 }
389 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
7368a6c8 390 server_version_string = xstrdup(buf);
391
7b390973 392 /* Send our protocol version identification. */
393 if (atomicio(vwrite, sock_out, server_version_string,
394 strlen(server_version_string))
395 != strlen(server_version_string)) {
396 logit("Could not write ident string to %s", get_remote_ipaddr());
2362db19 397 cleanup_exit(255);
7b390973 398 }
399
400 /* Read other sides version identification. */
401 memset(buf, 0, sizeof(buf));
402 for (i = 0; i < sizeof(buf) - 1; i++) {
403 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
404 logit("Did not receive identification string from %s",
405 get_remote_ipaddr());
2362db19 406 cleanup_exit(255);
7368a6c8 407 }
7b390973 408 if (buf[i] == '\r') {
409 buf[i] = 0;
410 /* Kludge for F-Secure Macintosh < 1.0.2 */
411 if (i == 12 &&
412 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
7368a6c8 413 break;
7b390973 414 continue;
415 }
416 if (buf[i] == '\n') {
417 buf[i] = 0;
418 break;
7368a6c8 419 }
7368a6c8 420 }
7b390973 421 buf[sizeof(buf) - 1] = 0;
422 client_version_string = xstrdup(buf);
7368a6c8 423
424 /*
425 * Check that the versions match. In future this might accept
426 * several versions and set appropriate flags to handle them.
427 */
428 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
429 &remote_major, &remote_minor, remote_version) != 3) {
6ae2364d 430 s = "Protocol mismatch.\n";
dc54438a 431 (void) atomicio(vwrite, sock_out, s, strlen(s));
7368a6c8 432 close(sock_in);
433 close(sock_out);
bbe88b6d 434 logit("Bad protocol version identification '%.100s' from %s",
7368a6c8 435 client_version_string, get_remote_ipaddr());
2362db19 436 cleanup_exit(255);
7368a6c8 437 }
438 debug("Client protocol version %d.%d; client software version %.100s",
184eed6a 439 remote_major, remote_minor, remote_version);
7368a6c8 440
e78a59f5 441 compat_datafellows(remote_version);
442
9a87e2ac 443 if (datafellows & SSH_BUG_PROBE) {
bbe88b6d 444 logit("probed from %s with %s. Don't panic.",
9a87e2ac 445 get_remote_ipaddr(), client_version_string);
2362db19 446 cleanup_exit(255);
9a87e2ac 447 }
448
3a1c54d4 449 if (datafellows & SSH_BUG_SCANNER) {
bbe88b6d 450 logit("scanned from %s with %s. Don't panic.",
3a1c54d4 451 get_remote_ipaddr(), client_version_string);
2362db19 452 cleanup_exit(255);
3a1c54d4 453 }
454
a8be9f80 455 mismatch = 0;
6aacefa7 456 switch (remote_major) {
7368a6c8 457 case 1:
a306f2dd 458 if (remote_minor == 99) {
459 if (options.protocol & SSH_PROTO_2)
460 enable_compat20();
461 else
462 mismatch = 1;
463 break;
464 }
a8be9f80 465 if (!(options.protocol & SSH_PROTO_1)) {
466 mismatch = 1;
467 break;
468 }
7368a6c8 469 if (remote_minor < 3) {
089fbbd2 470 packet_disconnect("Your ssh version is too old and "
7368a6c8 471 "is no longer supported. Please install a newer version.");
472 } else if (remote_minor == 3) {
473 /* note that this disables agent-forwarding */
474 enable_compat13();
475 }
a8be9f80 476 break;
e78a59f5 477 case 2:
a8be9f80 478 if (options.protocol & SSH_PROTO_2) {
e78a59f5 479 enable_compat20();
480 break;
481 }
482 /* FALLTHROUGH */
6ae2364d 483 default:
a8be9f80 484 mismatch = 1;
485 break;
486 }
487 chop(server_version_string);
a8be9f80 488 debug("Local version string %.200s", server_version_string);
489
490 if (mismatch) {
7368a6c8 491 s = "Protocol major versions differ.\n";
dc54438a 492 (void) atomicio(vwrite, sock_out, s, strlen(s));
7368a6c8 493 close(sock_in);
494 close(sock_out);
bbe88b6d 495 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
a8be9f80 496 get_remote_ipaddr(),
497 server_version_string, client_version_string);
2362db19 498 cleanup_exit(255);
7368a6c8 499 }
a306f2dd 500}
501
fa08c86b 502/* Destroy the host and server keys. They will no longer be needed. */
a306f2dd 503void
504destroy_sensitive_data(void)
505{
fa08c86b 506 int i;
507
508 if (sensitive_data.server_key) {
509 key_free(sensitive_data.server_key);
510 sensitive_data.server_key = NULL;
511 }
184eed6a 512 for (i = 0; i < options.num_host_key_files; i++) {
fa08c86b 513 if (sensitive_data.host_keys[i]) {
514 key_free(sensitive_data.host_keys[i]);
515 sensitive_data.host_keys[i] = NULL;
516 }
517 }
518 sensitive_data.ssh1_host_key = NULL;
00be5382 519 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
fa08c86b 520}
fa08c86b 521
1853d1ef 522/* Demote private to public keys for network child */
523void
524demote_sensitive_data(void)
525{
526 Key *tmp;
527 int i;
528
529 if (sensitive_data.server_key) {
530 tmp = key_demote(sensitive_data.server_key);
531 key_free(sensitive_data.server_key);
532 sensitive_data.server_key = tmp;
533 }
534
535 for (i = 0; i < options.num_host_key_files; i++) {
536 if (sensitive_data.host_keys[i]) {
537 tmp = key_demote(sensitive_data.host_keys[i]);
538 key_free(sensitive_data.host_keys[i]);
539 sensitive_data.host_keys[i] = tmp;
540 if (tmp->type == KEY_RSA1)
541 sensitive_data.ssh1_host_key = tmp;
542 }
543 }
544
545 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
546}
547
51aeb639 548static void
1853d1ef 549privsep_preauth_child(void)
550{
7fdc56c5 551 u_int32_t rnd[256];
6ded293b 552 gid_t gidset[1];
2ea6de2b 553 struct passwd *pw;
e424e241 554 int i;
1853d1ef 555
556 /* Enable challenge-response authentication for privilege separation */
557 privsep_challenge_enable();
558
559 for (i = 0; i < 256; i++)
7fdc56c5 560 rnd[i] = arc4random();
561 RAND_seed(rnd, sizeof(rnd));
1853d1ef 562
563 /* Demote the private keys to public keys. */
564 demote_sensitive_data();
565
2ea6de2b 566 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
cdc4fc39 567 fatal("Privilege separation user %s does not exist",
568 SSH_PRIVSEP_USER);
2ea6de2b 569 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
570 endpwent();
571
343288b8 572 /* Change our root directory */
1c352e97 573 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
574 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
575 strerror(errno));
1853d1ef 576 if (chdir("/") == -1)
edfb66cb 577 fatal("chdir(\"/\"): %s", strerror(errno));
762715ce 578
1853d1ef 579 /* Drop our privileges */
2ea6de2b 580 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
581 (u_int)pw->pw_gid);
87809a1f 582#if 0
6ff58a4b 583 /* XXX not ready, too heavy after chroot */
2ea6de2b 584 do_setusercontext(pw);
87809a1f 585#else
586 gidset[0] = pw->pw_gid;
87809a1f 587 if (setgroups(1, gidset) < 0)
588 fatal("setgroups: %.100s", strerror(errno));
589 permanently_set_uid(pw);
590#endif
1853d1ef 591}
592
2362db19 593static int
594privsep_preauth(Authctxt *authctxt)
1853d1ef 595{
1853d1ef 596 int status;
324bf712 597 pid_t pid;
1853d1ef 598
324bf712 599 /* Set up unprivileged child process to deal with network data */
b5a28cbc 600 pmonitor = monitor_init();
324bf712 601 /* Store a pointer to the kex for later rekeying */
b5a28cbc 602 pmonitor->m_pkex = &xxx_kex;
324bf712 603
604 pid = fork();
605 if (pid == -1) {
606 fatal("fork of unprivileged child failed");
607 } else if (pid != 0) {
c457707e 608 debug2("Network child is on pid %ld", (long)pid);
324bf712 609
b5a28cbc 610 close(pmonitor->m_recvfd);
a9b33b95 611 pmonitor->m_pid = pid;
2362db19 612 monitor_child_preauth(authctxt, pmonitor);
b5a28cbc 613 close(pmonitor->m_sendfd);
324bf712 614
615 /* Sync memory */
b5a28cbc 616 monitor_sync(pmonitor);
324bf712 617
618 /* Wait for the child's exit status */
8c38e88b 619 while (waitpid(pid, &status, 0) < 0)
620 if (errno != EINTR)
621 break;
2362db19 622 return (1);
324bf712 623 } else {
624 /* child */
625
b5a28cbc 626 close(pmonitor->m_sendfd);
324bf712 627
628 /* Demote the child */
629 if (getuid() == 0 || geteuid() == 0)
630 privsep_preauth_child();
47c36e5b 631 setproctitle("%s", "[net]");
324bf712 632 }
2362db19 633 return (0);
324bf712 634}
635
636static void
637privsep_postauth(Authctxt *authctxt)
638{
94d8258b 639#ifdef DISABLE_FD_PASSING
d170feb1 640 if (1) {
641#else
1853d1ef 642 if (authctxt->pw->pw_uid == 0 || options.use_login) {
d170feb1 643#endif
1853d1ef 644 /* File descriptor passing is broken or root login */
b5a28cbc 645 monitor_apply_keystate(pmonitor);
1853d1ef 646 use_privsep = 0;
647 return;
648 }
762715ce 649
1853d1ef 650 /* Authentication complete */
651 alarm(0);
652 if (startup_pipe != -1) {
653 close(startup_pipe);
654 startup_pipe = -1;
655 }
656
657 /* New socket pair */
b5a28cbc 658 monitor_reinit(pmonitor);
1853d1ef 659
b5a28cbc 660 pmonitor->m_pid = fork();
661 if (pmonitor->m_pid == -1)
1853d1ef 662 fatal("fork of unprivileged child failed");
b5a28cbc 663 else if (pmonitor->m_pid != 0) {
c457707e 664 debug2("User child is on pid %ld", (long)pmonitor->m_pid);
b5a28cbc 665 close(pmonitor->m_recvfd);
666 monitor_child_postauth(pmonitor);
1853d1ef 667
668 /* NEVERREACHED */
669 exit(0);
670 }
671
b5a28cbc 672 close(pmonitor->m_sendfd);
1853d1ef 673
674 /* Demote the private keys to public keys. */
675 demote_sensitive_data();
676
677 /* Drop privileges */
678 do_setusercontext(authctxt->pw);
679
680 /* It is safe now to apply the key state */
b5a28cbc 681 monitor_apply_keystate(pmonitor);
1853d1ef 682}
683
396c147e 684static char *
fa08c86b 685list_hostkey_types(void)
686{
3469eac4 687 Buffer b;
b6c7b7b7 688 const char *p;
689 char *ret;
fa08c86b 690 int i;
3469eac4 691
692 buffer_init(&b);
184eed6a 693 for (i = 0; i < options.num_host_key_files; i++) {
fa08c86b 694 Key *key = sensitive_data.host_keys[i];
695 if (key == NULL)
696 continue;
6aacefa7 697 switch (key->type) {
fa08c86b 698 case KEY_RSA:
699 case KEY_DSA:
3469eac4 700 if (buffer_len(&b) > 0)
701 buffer_append(&b, ",", 1);
702 p = key_ssh_name(key);
703 buffer_append(&b, p, strlen(p));
fa08c86b 704 break;
705 }
706 }
3469eac4 707 buffer_append(&b, "\0", 1);
b6c7b7b7 708 ret = xstrdup(buffer_ptr(&b));
3469eac4 709 buffer_free(&b);
b6c7b7b7 710 debug("list_hostkey_types: %s", ret);
711 return ret;
fa08c86b 712}
713
1853d1ef 714Key *
fa08c86b 715get_hostkey_by_type(int type)
716{
717 int i;
e424e241 718
184eed6a 719 for (i = 0; i < options.num_host_key_files; i++) {
fa08c86b 720 Key *key = sensitive_data.host_keys[i];
721 if (key != NULL && key->type == type)
722 return key;
723 }
724 return NULL;
7368a6c8 725}
726
1853d1ef 727Key *
728get_hostkey_by_index(int ind)
729{
730 if (ind < 0 || ind >= options.num_host_key_files)
731 return (NULL);
732 return (sensitive_data.host_keys[ind]);
733}
734
735int
736get_hostkey_index(Key *key)
737{
738 int i;
e424e241 739
1853d1ef 740 for (i = 0; i < options.num_host_key_files; i++) {
741 if (key == sensitive_data.host_keys[i])
742 return (i);
743 }
744 return (-1);
745}
746
c345cf9d 747/*
748 * returns 1 if connection should be dropped, 0 otherwise.
749 * dropping starts at connection #max_startups_begin with a probability
750 * of (max_startups_rate/100). the probability increases linearly until
751 * all connections are dropped for startups > max_startups
752 */
396c147e 753static int
c345cf9d 754drop_connection(int startups)
755{
756 double p, r;
757
758 if (startups < options.max_startups_begin)
759 return 0;
760 if (startups >= options.max_startups)
761 return 1;
762 if (options.max_startups_rate == 100)
763 return 1;
764
765 p = 100 - options.max_startups_rate;
766 p *= startups - options.max_startups_begin;
767 p /= (double) (options.max_startups - options.max_startups_begin);
768 p += options.max_startups_rate;
769 p /= 100.0;
770 r = arc4random() / (double) UINT_MAX;
771
772 debug("drop_connection: p %g, r %g", p, r);
773 return (r < p) ? 1 : 0;
774}
775
2717fa0f 776static void
777usage(void)
778{
85ac7a84 779 fprintf(stderr, "%s, %s\n",
418ae4b4 780 SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
65edde94 781 fprintf(stderr,
782"usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
783" [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
784 );
2717fa0f 785 exit(1);
786}
787
b9a549d7 788static void
789send_rexec_state(int fd, Buffer *conf)
790{
791 Buffer m;
792
793 debug3("%s: entering fd = %d config len %d", __func__, fd,
794 buffer_len(conf));
795
796 /*
797 * Protocol from reexec master to child:
798 * string configuration
799 * u_int ephemeral_key_follows
800 * bignum e (only if ephemeral_key_follows == 1)
801 * bignum n "
802 * bignum d "
803 * bignum iqmp "
804 * bignum p "
805 * bignum q "
806 */
807 buffer_init(&m);
808 buffer_put_cstring(&m, buffer_ptr(conf));
809
810 if (sensitive_data.server_key != NULL &&
811 sensitive_data.server_key->type == KEY_RSA1) {
812 buffer_put_int(&m, 1);
813 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
814 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
815 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
816 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
817 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
818 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
819 } else
820 buffer_put_int(&m, 0);
821
822 if (ssh_msg_send(fd, 0, &m) == -1)
823 fatal("%s: ssh_msg_send failed", __func__);
824
825 buffer_free(&m);
826
827 debug3("%s: done", __func__);
828}
829
830static void
831recv_rexec_state(int fd, Buffer *conf)
832{
833 Buffer m;
834 char *cp;
835 u_int len;
836
837 debug3("%s: entering fd = %d", __func__, fd);
838
839 buffer_init(&m);
840
841 if (ssh_msg_recv(fd, &m) == -1)
842 fatal("%s: ssh_msg_recv failed", __func__);
843 if (buffer_get_char(&m) != 0)
844 fatal("%s: rexec version mismatch", __func__);
845
846 cp = buffer_get_string(&m, &len);
847 if (conf != NULL)
848 buffer_append(conf, cp, len + 1);
849 xfree(cp);
850
851 if (buffer_get_int(&m)) {
852 if (sensitive_data.server_key != NULL)
853 key_free(sensitive_data.server_key);
854 sensitive_data.server_key = key_new_private(KEY_RSA1);
855 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
856 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
857 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
858 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
859 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
860 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
861 rsa_generate_additional_parameters(
862 sensitive_data.server_key->rsa);
863 }
864 buffer_free(&m);
865
866 debug3("%s: done", __func__);
867}
868
5260325f 869/*
870 * Main program for the daemon.
871 */
8efc0c15 872int
873main(int ac, char **av)
874{
5260325f 875 extern char *optarg;
876 extern int optind;
83529a6b 877 int opt, j, i, fdsetsz, on = 1;
878 int sock_in = -1, sock_out = -1, newsock = -1;
9da5c3c9 879 pid_t pid;
48e671d5 880 socklen_t fromlen;
48e671d5 881 fd_set *fdset;
882 struct sockaddr_storage from;
5260325f 883 const char *remote_ip;
884 int remote_port;
5260325f 885 FILE *f;
48e671d5 886 struct addrinfo *ai;
887 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
c5894280 888 char *line;
48e671d5 889 int listen_sock, maxfd;
b9a549d7 890 int startup_p[2], config_s[2];
089fbbd2 891 int startups = 0;
aeaa3d9e 892 Key *key;
2362db19 893 Authctxt *authctxt;
59c97189 894 int ret, key_used = 0;
b9a549d7 895 Buffer cfg;
5260325f 896
6e879cb4 897#ifdef HAVE_SECUREWARE
898 (void)set_auth_parameters(ac, av);
899#endif
fda04d7d 900 __progname = ssh_get_progname(av[0]);
264dce47 901 init_rng();
902
d0104542 903 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
4d33e531 904 saved_argc = ac;
7706b4c7 905 rexec_argc = ac;
f420d2ba 906 saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
d0104542 907 for (i = 0; i < ac; i++)
908 saved_argv[i] = xstrdup(av[i]);
f420d2ba 909 saved_argv[i] = NULL;
d0104542 910
911#ifndef HAVE_SETPROCTITLE
912 /* Prepare for later setproctitle emulation */
913 compat_init_setproctitle(ac, av);
416c732d 914 av = saved_argv;
d0104542 915#endif
5260325f 916
a4c0faa2 917 if (geteuid() == 0 && setgroups(0, NULL) == -1)
918 debug("setgroups(): %.200s", strerror(errno));
919
5260325f 920 /* Initialize configuration options to their default values. */
921 initialize_server_options(&options);
922
923 /* Parse command-line arguments. */
b9a549d7 924 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
5260325f 925 switch (opt) {
48e671d5 926 case '4':
927 IPv4or6 = AF_INET;
928 break;
929 case '6':
930 IPv4or6 = AF_INET6;
931 break;
5260325f 932 case 'f':
933 config_file_name = optarg;
934 break;
935 case 'd':
e053cd2c 936 if (debug_flag == 0) {
bcbf86ec 937 debug_flag = 1;
938 options.log_level = SYSLOG_LEVEL_DEBUG1;
e053cd2c 939 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
bcbf86ec 940 options.log_level++;
5260325f 941 break;
0b6fbf03 942 case 'D':
943 no_daemon_flag = 1;
944 break;
ff14faf1 945 case 'e':
946 log_stderr = 1;
947 break;
5260325f 948 case 'i':
949 inetd_flag = 1;
950 break;
b9a549d7 951 case 'r':
952 rexec_flag = 0;
953 break;
954 case 'R':
955 rexeced_flag = 1;
956 inetd_flag = 1;
957 break;
5260325f 958 case 'Q':
9bd5b720 959 /* ignored */
5260325f 960 break;
961 case 'q':
962 options.log_level = SYSLOG_LEVEL_QUIET;
963 break;
964 case 'b':
965 options.server_key_bits = atoi(optarg);
966 break;
967 case 'p':
48e671d5 968 options.ports_from_cmdline = 1;
bcbf86ec 969 if (options.num_ports >= MAX_PORTS) {
970 fprintf(stderr, "too many ports.\n");
971 exit(1);
972 }
2d2a2c65 973 options.ports[options.num_ports++] = a2port(optarg);
974 if (options.ports[options.num_ports-1] == 0) {
975 fprintf(stderr, "Bad port number.\n");
976 exit(1);
977 }
5260325f 978 break;
979 case 'g':
e2b1fb42 980 if ((options.login_grace_time = convtime(optarg)) == -1) {
981 fprintf(stderr, "Invalid login grace time.\n");
982 exit(1);
983 }
5260325f 984 break;
985 case 'k':
e2b1fb42 986 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
987 fprintf(stderr, "Invalid key regeneration interval.\n");
988 exit(1);
989 }
5260325f 990 break;
991 case 'h':
fa08c86b 992 if (options.num_host_key_files >= MAX_HOSTKEYS) {
993 fprintf(stderr, "too many host keys.\n");
994 exit(1);
995 }
996 options.host_key_files[options.num_host_key_files++] = optarg;
5260325f 997 break;
f87f09aa 998 case 't':
999 test_flag = 1;
1000 break;
c345cf9d 1001 case 'u':
1002 utmp_len = atoi(optarg);
67f04db1 1003 if (utmp_len > MAXHOSTNAMELEN) {
1004 fprintf(stderr, "Invalid utmp length.\n");
1005 exit(1);
1006 }
c345cf9d 1007 break;
2717fa0f 1008 case 'o':
c5894280 1009 line = xstrdup(optarg);
1010 if (process_server_config_line(&options, line,
2717fa0f 1011 "command-line", 0) != 0)
184eed6a 1012 exit(1);
c5894280 1013 xfree(line);
2717fa0f 1014 break;
5260325f 1015 case '?':
1016 default:
2717fa0f 1017 usage();
1018 break;
5260325f 1019 }
1020 }
b9a549d7 1021 if (rexeced_flag || inetd_flag)
1022 rexec_flag = 0;
1023 if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1024 fatal("sshd re-exec requires execution with an absolute path");
1025 if (rexeced_flag)
b250e837 1026 closefrom(REEXEC_MIN_FREE_FD);
1027 else
1028 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
b9a549d7 1029
1a92bd7e 1030 SSLeay_add_all_algorithms();
5e4a7219 1031 channel_set_af(IPv4or6);
5260325f 1032
48e671d5 1033 /*
1034 * Force logging to stderr until we have loaded the private host
1035 * key (unless started from inetd)
1036 */
1fe6a48f 1037 log_init(__progname,
980c9344 1038 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1039 SYSLOG_LEVEL_INFO : options.log_level,
1040 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1041 SYSLOG_FACILITY_AUTH : options.log_facility,
51efad8c 1042 log_stderr || !inetd_flag);
48e671d5 1043
351f44a0 1044#ifdef _AIX
1045 /*
1046 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1047 * root's environment
1048 */
1049 unsetenv("KRB5CCNAME");
1050#endif /* _AIX */
ef51930f 1051#ifdef _UNICOS
e5ba4718 1052 /* Cray can define user privs drop all privs now!
1a23ac2c 1053 * Not needed on PRIV_SU systems!
1054 */
1055 drop_cray_privs();
1056#endif
1057
e339aa53 1058 seed_rng();
1059
b9a549d7 1060 sensitive_data.server_key = NULL;
1061 sensitive_data.ssh1_host_key = NULL;
1062 sensitive_data.have_ssh1_key = 0;
1063 sensitive_data.have_ssh2_key = 0;
1064
1065 /* Fetch our configuration */
1066 buffer_init(&cfg);
1067 if (rexeced_flag)
b250e837 1068 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
b9a549d7 1069 else
1070 load_server_config(config_file_name, &cfg);
1071
1072 parse_server_config(&options,
1073 rexeced_flag ? "rexec" : config_file_name, &cfg);
1074
1075 if (!rexec_flag)
1076 buffer_free(&cfg);
5260325f 1077
1078 /* Fill in default values for those options not explicitly set. */
1079 fill_default_server_options(&options);
1080
5260325f 1081 /* Check that there are no remaining arguments. */
1082 if (optind < ac) {
1083 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1084 exit(1);
8efc0c15 1085 }
5260325f 1086
1087 debug("sshd version %.100s", SSH_VERSION);
1088
fa08c86b 1089 /* load private host keys */
343288b8 1090 sensitive_data.host_keys = xmalloc(options.num_host_key_files *
1091 sizeof(Key *));
184eed6a 1092 for (i = 0; i < options.num_host_key_files; i++)
1e3b8b07 1093 sensitive_data.host_keys[i] = NULL;
a306f2dd 1094
184eed6a 1095 for (i = 0; i < options.num_host_key_files; i++) {
aeaa3d9e 1096 key = key_load_private(options.host_key_files[i], "", NULL);
1097 sensitive_data.host_keys[i] = key;
fa08c86b 1098 if (key == NULL) {
58cfa257 1099 error("Could not load host key: %s",
1100 options.host_key_files[i]);
aeaa3d9e 1101 sensitive_data.host_keys[i] = NULL;
fa08c86b 1102 continue;
a306f2dd 1103 }
6aacefa7 1104 switch (key->type) {
fa08c86b 1105 case KEY_RSA1:
1106 sensitive_data.ssh1_host_key = key;
1107 sensitive_data.have_ssh1_key = 1;
1108 break;
1109 case KEY_RSA:
1110 case KEY_DSA:
1111 sensitive_data.have_ssh2_key = 1;
1112 break;
a306f2dd 1113 }
aeaa3d9e 1114 debug("private host key: #%d type %d %s", i, key->type,
1115 key_type(key));
fa08c86b 1116 }
1117 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
bbe88b6d 1118 logit("Disabling protocol version 1. Could not load host key");
fa08c86b 1119 options.protocol &= ~SSH_PROTO_1;
1120 }
1121 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
bbe88b6d 1122 logit("Disabling protocol version 2. Could not load host key");
fa08c86b 1123 options.protocol &= ~SSH_PROTO_2;
a306f2dd 1124 }
6a416424 1125 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
bbe88b6d 1126 logit("sshd: no hostkeys available -- exiting.");
5260325f 1127 exit(1);
1128 }
5260325f 1129
a306f2dd 1130 /* Check certain values for sanity. */
1131 if (options.protocol & SSH_PROTO_1) {
1132 if (options.server_key_bits < 512 ||
1133 options.server_key_bits > 32768) {
1134 fprintf(stderr, "Bad server key size.\n");
1135 exit(1);
1136 }
1137 /*
1138 * Check that server and host key lengths differ sufficiently. This
1139 * is necessary to make double encryption work with rsaref. Oh, I
1140 * hate software patents. I dont know if this can go? Niels
1141 */
1142 if (options.server_key_bits >
e424e241 1143 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1144 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1145 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1146 SSH_KEY_BITS_RESERVED) {
a306f2dd 1147 options.server_key_bits =
e424e241 1148 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1149 SSH_KEY_BITS_RESERVED;
a306f2dd 1150 debug("Forcing server key to %d bits to make it differ from host key.",
1151 options.server_key_bits);
1152 }
1153 }
1154
3cc54fbb 1155 if (use_privsep) {
1156 struct passwd *pw;
1157 struct stat st;
1158
1159 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1160 fatal("Privilege separation user %s does not exist",
1161 SSH_PRIVSEP_USER);
1162 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1163 (S_ISDIR(st.st_mode) == 0))
1164 fatal("Missing privilege separation directory: %s",
1165 _PATH_PRIVSEP_CHROOT_DIR);
b9b82dab 1166
1167#ifdef HAVE_CYGWIN
1168 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1169 (st.st_uid != getuid () ||
1170 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1171#else
a56313d7 1172 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
b9b82dab 1173#endif
5f021474 1174 fatal("%s must be owned by root and not group or "
1175 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
3cc54fbb 1176 }
1177
f87f09aa 1178 /* Configuration looks good, so exit if in test mode. */
1179 if (test_flag)
1180 exit(0);
1181
018a5ea3 1182 /*
1183 * Clear out any supplemental groups we may have inherited. This
1184 * prevents inadvertent creation of files with bad modes (in the
aff51935 1185 * portable version at least, it's certainly possible for PAM
1186 * to create a file, and we can't control the code in every
018a5ea3 1187 * module which might be used).
1188 */
1189 if (setgroups(0, NULL) < 0)
1190 debug("setgroups() failed: %.200s", strerror(errno));
1191
b9a549d7 1192 if (rexec_flag) {
1193 rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
1194 for (i = 0; i < rexec_argc; i++) {
1195 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1196 rexec_argv[i] = saved_argv[i];
1197 }
1198 rexec_argv[rexec_argc] = "-R";
1199 rexec_argv[rexec_argc + 1] = NULL;
1200 }
1201
a306f2dd 1202 /* Initialize the log (it is reinitialized below in case we forked). */
5260325f 1203 if (debug_flag && !inetd_flag)
1204 log_stderr = 1;
1fe6a48f 1205 log_init(__progname, options.log_level, options.log_facility, log_stderr);
5260325f 1206
a306f2dd 1207 /*
1208 * If not in debugging mode, and not started from inetd, disconnect
1209 * from the controlling terminal, and fork. The original process
1210 * exits.
1211 */
0b6fbf03 1212 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
8efc0c15 1213#ifdef TIOCNOTTY
5260325f 1214 int fd;
8efc0c15 1215#endif /* TIOCNOTTY */
5260325f 1216 if (daemon(0, 0) < 0)
1217 fatal("daemon() failed: %.200s", strerror(errno));
1218
1219 /* Disconnect from the controlling tty. */
8efc0c15 1220#ifdef TIOCNOTTY
5ca51e19 1221 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
5260325f 1222 if (fd >= 0) {
1223 (void) ioctl(fd, TIOCNOTTY, NULL);
1224 close(fd);
1225 }
8efc0c15 1226#endif /* TIOCNOTTY */
8efc0c15 1227 }
5260325f 1228 /* Reinitialize the log (because of the fork above). */
1fe6a48f 1229 log_init(__progname, options.log_level, options.log_facility, log_stderr);
5260325f 1230
5260325f 1231 /* Initialize the random number generator. */
1232 arc4random_stir();
1233
1234 /* Chdir to the root directory so that the current disk can be
1235 unmounted if desired. */
1236 chdir("/");
184eed6a 1237
1d3c30db 1238 /* ignore SIGPIPE */
1239 signal(SIGPIPE, SIG_IGN);
5260325f 1240
5260325f 1241 /* Start listening for a socket, unless started from inetd. */
1242 if (inetd_flag) {
b9a549d7 1243 int fd;
1244
4c8722d9 1245 startup_pipe = -1;
b9a549d7 1246 if (rexeced_flag) {
b250e837 1247 close(REEXEC_CONFIG_PASS_FD);
b9a549d7 1248 sock_in = sock_out = dup(STDIN_FILENO);
1249 if (!debug_flag) {
b250e837 1250 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1251 close(REEXEC_STARTUP_PIPE_FD);
b9a549d7 1252 }
1253 } else {
1254 sock_in = dup(STDIN_FILENO);
1255 sock_out = dup(STDOUT_FILENO);
1256 }
a306f2dd 1257 /*
1258 * We intentionally do not close the descriptors 0, 1, and 2
b9a549d7 1259 * as our code for setting the descriptors won't work if
a306f2dd 1260 * ttyfd happens to be one of those.
1261 */
b9a549d7 1262 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1263 dup2(fd, STDIN_FILENO);
1264 dup2(fd, STDOUT_FILENO);
1265 if (fd > STDOUT_FILENO)
1266 close(fd);
1267 }
5260325f 1268 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
b9a549d7 1269 if ((options.protocol & SSH_PROTO_1) &&
1270 sensitive_data.server_key == NULL)
cb7bd922 1271 generate_ephemeral_server_key();
5260325f 1272 } else {
48e671d5 1273 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1274 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1275 continue;
1276 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1277 fatal("Too many listen sockets. "
1278 "Enlarge MAX_LISTEN_SOCKS");
1279 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
1280 ntop, sizeof(ntop), strport, sizeof(strport),
1281 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1282 error("getnameinfo failed");
1283 continue;
1284 }
1285 /* Create socket for listening. */
3e131a6d 1286 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1287 ai->ai_protocol);
48e671d5 1288 if (listen_sock < 0) {
1289 /* kernel may not support ipv6 */
1290 verbose("socket: %.100s", strerror(errno));
1291 continue;
1292 }
170694d7 1293 if (set_nonblock(listen_sock) == -1) {
a666e3b1 1294 close(listen_sock);
1295 continue;
1296 }
48e671d5 1297 /*
facfd613 1298 * Set socket options.
1299 * Allow local port reuse in TIME_WAIT.
48e671d5 1300 */
facfd613 1301 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1302 &on, sizeof(on)) == -1)
1303 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
48e671d5 1304
1305 debug("Bind to port %s on %s.", strport, ntop);
1306
1307 /* Bind the socket to the desired port. */
32ced054 1308 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1309 if (!ai->ai_next)
1310 error("Bind to port %s on %s failed: %.200s.",
1311 strport, ntop, strerror(errno));
48e671d5 1312 close(listen_sock);
1313 continue;
1314 }
1315 listen_socks[num_listen_socks] = listen_sock;
1316 num_listen_socks++;
1317
1318 /* Start listening on the port. */
bbe88b6d 1319 logit("Server listening on %s port %s.", ntop, strport);
fce39749 1320 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
48e671d5 1321 fatal("listen: %.100s", strerror(errno));
1322
5260325f 1323 }
48e671d5 1324 freeaddrinfo(options.listen_addrs);
1325
1326 if (!num_listen_socks)
1327 fatal("Cannot bind any address.");
1328
3aca00a3 1329 if (options.protocol & SSH_PROTO_1)
1330 generate_ephemeral_server_key();
1331
1332 /*
1333 * Arrange to restart on SIGHUP. The handler needs
1334 * listen_sock.
1335 */
1336 signal(SIGHUP, sighup_handler);
1337
1338 signal(SIGTERM, sigterm_handler);
1339 signal(SIGQUIT, sigterm_handler);
1340
1341 /* Arrange SIGCHLD to be caught. */
1342 signal(SIGCHLD, main_sigchld_handler);
1343
1344 /* Write out the pid file after the sigterm handler is setup */
5260325f 1345 if (!debug_flag) {
aa3378df 1346 /*
97fb6912 1347 * Record our pid in /var/run/sshd.pid to make it
1348 * easier to kill the correct sshd. We don't want to
1349 * do this before the bind above because the bind will
aa3378df 1350 * fail if there already is a daemon, and this will
1351 * overwrite any old pid in the file.
1352 */
3c62e7eb 1353 f = fopen(options.pid_file, "wb");
71b9ced0 1354 if (f == NULL) {
1355 error("Couldn't create pid file \"%s\": %s",
1356 options.pid_file, strerror(errno));
1357 } else {
c457707e 1358 fprintf(f, "%ld\n", (long) getpid());
5260325f 1359 fclose(f);
1360 }
8efc0c15 1361 }
5260325f 1362
48e671d5 1363 /* setup fd set for listen */
089fbbd2 1364 fdset = NULL;
48e671d5 1365 maxfd = 0;
1366 for (i = 0; i < num_listen_socks; i++)
1367 if (listen_socks[i] > maxfd)
1368 maxfd = listen_socks[i];
089fbbd2 1369 /* pipes connected to unauthenticated childs */
1370 startup_pipes = xmalloc(options.max_startups * sizeof(int));
1371 for (i = 0; i < options.max_startups; i++)
1372 startup_pipes[i] = -1;
48e671d5 1373
aa3378df 1374 /*
1375 * Stay listening for connections until the system crashes or
1376 * the daemon is killed with a signal.
1377 */
5260325f 1378 for (;;) {
1379 if (received_sighup)
1380 sighup_restart();
089fbbd2 1381 if (fdset != NULL)
1382 xfree(fdset);
b5c334cc 1383 fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
089fbbd2 1384 fdset = (fd_set *)xmalloc(fdsetsz);
48e671d5 1385 memset(fdset, 0, fdsetsz);
089fbbd2 1386
48e671d5 1387 for (i = 0; i < num_listen_socks; i++)
1388 FD_SET(listen_socks[i], fdset);
089fbbd2 1389 for (i = 0; i < options.max_startups; i++)
1390 if (startup_pipes[i] != -1)
1391 FD_SET(startup_pipes[i], fdset);
1392
1393 /* Wait in select until there is a connection. */
59c97189 1394 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1395 if (ret < 0 && errno != EINTR)
1396 error("select: %.100s", strerror(errno));
c9130033 1397 if (received_sigterm) {
bbe88b6d 1398 logit("Received signal %d; terminating.",
010f9726 1399 (int) received_sigterm);
c9130033 1400 close_listen_socks();
1401 unlink(options.pid_file);
1402 exit(255);
1403 }
59c97189 1404 if (key_used && key_do_regen) {
cb7bd922 1405 generate_ephemeral_server_key();
59c97189 1406 key_used = 0;
1407 key_do_regen = 0;
48e671d5 1408 }
59c97189 1409 if (ret < 0)
1410 continue;
1411
089fbbd2 1412 for (i = 0; i < options.max_startups; i++)
1413 if (startup_pipes[i] != -1 &&
1414 FD_ISSET(startup_pipes[i], fdset)) {
1415 /*
1416 * the read end of the pipe is ready
1417 * if the child has closed the pipe
8abcdba4 1418 * after successful authentication
089fbbd2 1419 * or if the child has died
1420 */
1421 close(startup_pipes[i]);
1422 startup_pipes[i] = -1;
1423 startups--;
1424 }
48e671d5 1425 for (i = 0; i < num_listen_socks; i++) {
1426 if (!FD_ISSET(listen_socks[i], fdset))
5260325f 1427 continue;
089fbbd2 1428 fromlen = sizeof(from);
1429 newsock = accept(listen_socks[i], (struct sockaddr *)&from,
1430 &fromlen);
1431 if (newsock < 0) {
1432 if (errno != EINTR && errno != EWOULDBLOCK)
1433 error("accept: %.100s", strerror(errno));
1434 continue;
1435 }
170694d7 1436 if (unset_nonblock(newsock) == -1) {
a666e3b1 1437 close(newsock);
1438 continue;
1439 }
c345cf9d 1440 if (drop_connection(startups) == 1) {
1441 debug("drop connection #%d", startups);
089fbbd2 1442 close(newsock);
1443 continue;
1444 }
1445 if (pipe(startup_p) == -1) {
1446 close(newsock);
1447 continue;
1448 }
1449
b9a549d7 1450 if (rexec_flag && socketpair(AF_UNIX,
1451 SOCK_STREAM, 0, config_s) == -1) {
1452 error("reexec socketpair: %s",
1453 strerror(errno));
1454 close(newsock);
1455 close(startup_p[0]);
1456 close(startup_p[1]);
1457 continue;
1458 }
1459
089fbbd2 1460 for (j = 0; j < options.max_startups; j++)
1461 if (startup_pipes[j] == -1) {
1462 startup_pipes[j] = startup_p[0];
1463 if (maxfd < startup_p[0])
1464 maxfd = startup_p[0];
1465 startups++;
1466 break;
1467 }
2b87da3b 1468
aa3378df 1469 /*
089fbbd2 1470 * Got connection. Fork a child to handle it, unless
1471 * we are in debugging mode.
aa3378df 1472 */
089fbbd2 1473 if (debug_flag) {
aa3378df 1474 /*
089fbbd2 1475 * In debugging mode. Close the listening
1476 * socket, and start processing the
1477 * connection without forking.
aa3378df 1478 */
089fbbd2 1479 debug("Server will not fork when running in debugging mode.");
48e671d5 1480 close_listen_socks();
5260325f 1481 sock_in = newsock;
1482 sock_out = newsock;
b9a549d7 1483 close(startup_p[0]);
1484 close(startup_p[1]);
5540ea9b 1485 startup_pipe = -1;
3f7a7e4a 1486 pid = getpid();
b9a549d7 1487 if (rexec_flag) {
1488 send_rexec_state(config_s[0],
1489 &cfg);
1490 close(config_s[0]);
1491 }
5260325f 1492 break;
089fbbd2 1493 } else {
1494 /*
1495 * Normal production daemon. Fork, and have
1496 * the child process the connection. The
1497 * parent continues listening.
1498 */
1499 if ((pid = fork()) == 0) {
1500 /*
1501 * Child. Close the listening and max_startup
1502 * sockets. Start using the accepted socket.
1503 * Reinitialize logging (since our pid has
1504 * changed). We break out of the loop to handle
1505 * the connection.
1506 */
1507 startup_pipe = startup_p[1];
7ace8c3b 1508 close_startup_pipes();
089fbbd2 1509 close_listen_socks();
1510 sock_in = newsock;
1511 sock_out = newsock;
1fe6a48f 1512 log_init(__progname, options.log_level, options.log_facility, log_stderr);
b250e837 1513 close(config_s[0]);
089fbbd2 1514 break;
1515 }
5260325f 1516 }
5260325f 1517
089fbbd2 1518 /* Parent. Stay in the loop. */
1519 if (pid < 0)
1520 error("fork: %.100s", strerror(errno));
1521 else
c457707e 1522 debug("Forked child %ld.", (long)pid);
5260325f 1523
089fbbd2 1524 close(startup_p[1]);
5260325f 1525
b9a549d7 1526 if (rexec_flag) {
1527 send_rexec_state(config_s[0], &cfg);
1528 close(config_s[0]);
1529 close(config_s[1]);
1530 }
1531
089fbbd2 1532 /* Mark that the key has been used (it was "given" to the child). */
59c97189 1533 if ((options.protocol & SSH_PROTO_1) &&
1534 key_used == 0) {
1535 /* Schedule server key regeneration alarm. */
f00d1f78 1536 signal(SIGALRM, key_regeneration_alarm);
59c97189 1537 alarm(options.key_regeneration_time);
1538 key_used = 1;
1539 }
5260325f 1540
089fbbd2 1541 arc4random_stir();
1542
1543 /* Close the new socket (the child is now taking care of it). */
1544 close(newsock);
1545 }
48e671d5 1546 /* child process check (or debug mode) */
1547 if (num_listen_socks < 0)
1548 break;
5260325f 1549 }
1550 }
8efc0c15 1551
5260325f 1552 /* This is the child processing a new connection. */
cc120685 1553 setproctitle("%s", "[accepted]");
5260325f 1554
b9a549d7 1555 if (rexec_flag) {
1556 int fd;
1557
b250e837 1558 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1559 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
b9a549d7 1560 dup2(newsock, STDIN_FILENO);
1561 dup2(STDIN_FILENO, STDOUT_FILENO);
1562 if (startup_pipe == -1)
b250e837 1563 close(REEXEC_STARTUP_PIPE_FD);
b9a549d7 1564 else
b250e837 1565 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
b9a549d7 1566
b250e837 1567 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
b9a549d7 1568 close(config_s[1]);
b250e837 1569 close(startup_pipe);
1570
b9a549d7 1571 execv(rexec_argv[0], rexec_argv);
1572
1573 /* Reexec has failed, fall back and continue */
1574 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
b250e837 1575 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
b9a549d7 1576 log_init(__progname, options.log_level,
1577 options.log_facility, log_stderr);
1578
1579 /* Clean up fds */
b250e837 1580 startup_pipe = REEXEC_STARTUP_PIPE_FD;
b9a549d7 1581 close(config_s[1]);
b250e837 1582 close(REEXEC_CONFIG_PASS_FD);
1583 newsock = sock_out = sock_in = dup(STDIN_FILENO);
b9a549d7 1584 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1585 dup2(fd, STDIN_FILENO);
1586 dup2(fd, STDOUT_FILENO);
1587 if (fd > STDERR_FILENO)
1588 close(fd);
1589 }
b250e837 1590 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1591 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
b9a549d7 1592 }
1593
4ac8556b 1594 /*
1595 * Create a new session and process group since the 4.4BSD
1596 * setlogin() affects the entire process group. We don't
1597 * want the child to be able to affect the parent.
1598 */
ad84c479 1599#if !defined(SSHD_ACQUIRES_CTTY)
6ecd00f8 1600 /*
ad84c479 1601 * If setsid is called, on some platforms sshd will later acquire a
1602 * controlling terminal which will result in "could not set
1603 * controlling tty" errors.
6ecd00f8 1604 */
c28876e9 1605 if (!debug_flag && !inetd_flag && setsid() < 0)
4ac8556b 1606 error("setsid: %.100s", strerror(errno));
30321a9b 1607#endif
4ac8556b 1608
aa3378df 1609 /*
1610 * Disable the key regeneration alarm. We will not regenerate the
1611 * key since we are no longer in a position to give it to anyone. We
1612 * will not restart on SIGHUP since it no longer makes sense.
1613 */
5260325f 1614 alarm(0);
1615 signal(SIGALRM, SIG_DFL);
1616 signal(SIGHUP, SIG_DFL);
1617 signal(SIGTERM, SIG_DFL);
1618 signal(SIGQUIT, SIG_DFL);
1619 signal(SIGCHLD, SIG_DFL);
9aaf9be4 1620 signal(SIGINT, SIG_DFL);
5260325f 1621
fd573618 1622 /* Set SO_KEEPALIVE if requested. */
1623 if (options.tcp_keep_alive &&
db518d9b 1624 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
b5c334cc 1625 sizeof(on)) < 0)
1626 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1627
aa3378df 1628 /*
1629 * Register our connection. This turns encryption off because we do
1630 * not have a key.
1631 */
5260325f 1632 packet_set_connection(sock_in, sock_out);
1633
1634 remote_port = get_remote_port();
1635 remote_ip = get_remote_ipaddr();
1636
5260325f 1637#ifdef LIBWRAP
ac28afd8 1638 /* Check whether logins are denied from this host. */
33e5359c 1639 if (packet_connection_is_on_socket()) {
5260325f 1640 struct request_info req;
8efc0c15 1641
8fbc356d 1642 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
5260325f 1643 fromhost(&req);
8efc0c15 1644
5260325f 1645 if (!hosts_access(&req)) {
ac28afd8 1646 debug("Connection refused by tcp wrapper");
563834bb 1647 refuse(&req);
ac28afd8 1648 /* NOTREACHED */
1649 fatal("libwrap refuse returns");
5260325f 1650 }
8efc0c15 1651 }
48e671d5 1652#endif /* LIBWRAP */
ac28afd8 1653
5260325f 1654 /* Log the connection. */
1655 verbose("Connection from %.500s port %d", remote_ip, remote_port);
8efc0c15 1656
aa3378df 1657 /*
1658 * We don\'t want to listen forever unless the other side
1659 * successfully authenticates itself. So we set up an alarm which is
1660 * cleared after successful authentication. A limit of zero
1661 * indicates no limit. Note that we don\'t set the alarm in debugging
1662 * mode; it is just annoying to have the server exit just when you
1663 * are about to discover the bug.
1664 */
f00d1f78 1665 signal(SIGALRM, grace_alarm_handler);
5260325f 1666 if (!debug_flag)
1667 alarm(options.login_grace_time);
1668
7368a6c8 1669 sshd_exchange_identification(sock_in, sock_out);
0598d99d 1670
5260325f 1671 packet_set_nonblocking();
1672
aff51935 1673 /* prepare buffers to collect authentication messages */
bc7dfc06 1674 buffer_init(&loginmsg);
1675
2362db19 1676 /* allocate authentication context */
1677 authctxt = xmalloc(sizeof(*authctxt));
1678 memset(authctxt, 0, sizeof(*authctxt));
1679
1680 /* XXX global for cleanup, access from other modules */
1681 the_authctxt = authctxt;
1682
324bf712 1683 if (use_privsep)
2362db19 1684 if (privsep_preauth(authctxt) == 1)
324bf712 1685 goto authenticated;
1853d1ef 1686
7b2ea3a1 1687 /* perform the key exchange */
7b2ea3a1 1688 /* authenticate user and start session */
e78a59f5 1689 if (compat20) {
1690 do_ssh2_kex();
2362db19 1691 do_authentication2(authctxt);
e78a59f5 1692 } else {
1693 do_ssh1_kex();
2362db19 1694 do_authentication(authctxt);
e78a59f5 1695 }
324bf712 1696 /*
1697 * If we use privilege separation, the unprivileged child transfers
1698 * the current keystate and exits
1699 */
1700 if (use_privsep) {
b5a28cbc 1701 mm_send_keystate(pmonitor);
1853d1ef 1702 exit(0);
324bf712 1703 }
1853d1ef 1704
1705 authenticated:
762715ce 1706 /*
1853d1ef 1707 * In privilege separation, we fork another child and prepare
1708 * file descriptor passing.
1709 */
1710 if (use_privsep) {
324bf712 1711 privsep_postauth(authctxt);
1712 /* the monitor process [priv] will not return */
1853d1ef 1713 if (!compat20)
1714 destroy_sensitive_data();
1715 }
1b34c1b3 1716
2362db19 1717 /* Start session. */
1b34c1b3 1718 do_authenticated(authctxt);
1719
63284fbb 1720 /* The connection has been terminated. */
1721 verbose("Closing connection to %.100s", remote_ip);
8efc0c15 1722
d94aa2ae 1723#ifdef USE_PAM
7fceb20d 1724 if (options.use_pam)
1725 finish_pam();
d94aa2ae 1726#endif /* USE_PAM */
8efc0c15 1727
5260325f 1728 packet_close();
1853d1ef 1729
1730 if (use_privsep)
1731 mm_terminate();
1732
5260325f 1733 exit(0);
1734}
8efc0c15 1735
4f08e98d 1736/*
1737 * Decrypt session_key_int using our private server key and private host key
1738 * (key with larger modulus first).
1739 */
1853d1ef 1740int
4f08e98d 1741ssh1_session_key(BIGNUM *session_key_int)
1742{
1743 int rsafail = 0;
1744
1745 if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1746 /* Server key has bigger modulus. */
1747 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1748 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1749 fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1750 get_remote_ipaddr(),
1751 BN_num_bits(sensitive_data.server_key->rsa->n),
1752 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1753 SSH_KEY_BITS_RESERVED);
1754 }
1755 if (rsa_private_decrypt(session_key_int, session_key_int,
1756 sensitive_data.server_key->rsa) <= 0)
1757 rsafail++;
1758 if (rsa_private_decrypt(session_key_int, session_key_int,
1759 sensitive_data.ssh1_host_key->rsa) <= 0)
1760 rsafail++;
1761 } else {
1762 /* Host key has bigger modulus (or they are equal). */
1763 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1764 BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1765 fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1766 get_remote_ipaddr(),
1767 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1768 BN_num_bits(sensitive_data.server_key->rsa->n),
1769 SSH_KEY_BITS_RESERVED);
1770 }
1771 if (rsa_private_decrypt(session_key_int, session_key_int,
1772 sensitive_data.ssh1_host_key->rsa) < 0)
1773 rsafail++;
1774 if (rsa_private_decrypt(session_key_int, session_key_int,
1775 sensitive_data.server_key->rsa) < 0)
1776 rsafail++;
1777 }
1778 return (rsafail);
1779}
5260325f 1780/*
7b2ea3a1 1781 * SSH1 key exchange
5260325f 1782 */
396c147e 1783static void
1e3b8b07 1784do_ssh1_kex(void)
8efc0c15 1785{
5260325f 1786 int i, len;
46aa2d1f 1787 int rsafail = 0;
5260325f 1788 BIGNUM *session_key_int;
1e3b8b07 1789 u_char session_key[SSH_SESSION_KEY_LENGTH];
1790 u_char cookie[8];
1791 u_int cipher_type, auth_mask, protocol_flags;
7fdc56c5 1792 u_int32_t rnd = 0;
5260325f 1793
aa3378df 1794 /*
1795 * Generate check bytes that the client must send back in the user
1796 * packet in order for it to be accepted; this is used to defy ip
1797 * spoofing attacks. Note that this only works against somebody
1798 * doing IP spoofing from a remote machine; any machine on the local
1799 * network can still see outgoing packets and catch the random
1800 * cookie. This only affects rhosts authentication, and this is one
1801 * of the reasons why it is inherently insecure.
1802 */
5260325f 1803 for (i = 0; i < 8; i++) {
1804 if (i % 4 == 0)
7fdc56c5 1805 rnd = arc4random();
1806 cookie[i] = rnd & 0xff;
1807 rnd >>= 8;
5260325f 1808 }
1809
aa3378df 1810 /*
1811 * Send our public key. We include in the packet 64 bits of random
1812 * data that must be matched in the reply in order to prevent IP
1813 * spoofing.
1814 */
5260325f 1815 packet_start(SSH_SMSG_PUBLIC_KEY);
1816 for (i = 0; i < 8; i++)
7b2ea3a1 1817 packet_put_char(cookie[i]);
5260325f 1818
1819 /* Store our public server RSA key. */
fa08c86b 1820 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1821 packet_put_bignum(sensitive_data.server_key->rsa->e);
1822 packet_put_bignum(sensitive_data.server_key->rsa->n);
5260325f 1823
1824 /* Store our public host RSA key. */
fa08c86b 1825 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1826 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1827 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
5260325f 1828
1829 /* Put protocol flags. */
1830 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1831
1832 /* Declare which ciphers we support. */
94ec8c6b 1833 packet_put_int(cipher_mask_ssh1(0));
5260325f 1834
1835 /* Declare supported authentication types. */
1836 auth_mask = 0;
5260325f 1837 if (options.rhosts_rsa_authentication)
1838 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1839 if (options.rsa_authentication)
1840 auth_mask |= 1 << SSH_AUTH_RSA;
5ba55ada 1841 if (options.challenge_response_authentication == 1)
5260325f 1842 auth_mask |= 1 << SSH_AUTH_TIS;
5260325f 1843 if (options.password_authentication)
1844 auth_mask |= 1 << SSH_AUTH_PASSWORD;
1845 packet_put_int(auth_mask);
1846
1847 /* Send the packet and wait for it to be sent. */
1848 packet_send();
1849 packet_write_wait();
1850
fa08c86b 1851 debug("Sent %d bit server key and %d bit host key.",
1852 BN_num_bits(sensitive_data.server_key->rsa->n),
1853 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
5260325f 1854
1855 /* Read clients reply (cipher type and session key). */
54a5250f 1856 packet_read_expect(SSH_CMSG_SESSION_KEY);
5260325f 1857
2d86a6cc 1858 /* Get cipher type and check whether we accept this. */
5260325f 1859 cipher_type = packet_get_char();
1860
94ec8c6b 1861 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2d86a6cc 1862 packet_disconnect("Warning: client selects unsupported cipher.");
1863
5260325f 1864 /* Get check bytes from the packet. These must match those we
1865 sent earlier with the public key packet. */
1866 for (i = 0; i < 8; i++)
7b2ea3a1 1867 if (cookie[i] != packet_get_char())
5260325f 1868 packet_disconnect("IP Spoofing check bytes do not match.");
1869
1870 debug("Encryption type: %.200s", cipher_name(cipher_type));
1871
1872 /* Get the encrypted integer. */
b775c6f2 1873 if ((session_key_int = BN_new()) == NULL)
1874 fatal("do_ssh1_kex: BN_new failed");
20b279e6 1875 packet_get_bignum(session_key_int);
5260325f 1876
5260325f 1877 protocol_flags = packet_get_int();
1878 packet_set_protocol_flags(protocol_flags);
95500969 1879 packet_check_eom();
5260325f 1880
4f08e98d 1881 /* Decrypt session_key_int using host/server keys */
1853d1ef 1882 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1883
aa3378df 1884 /*
1885 * Extract session key from the decrypted integer. The key is in the
1886 * least significant 256 bits of the integer; the first byte of the
1887 * key is in the highest bits.
1888 */
46aa2d1f 1889 if (!rsafail) {
1890 BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1891 len = BN_num_bytes(session_key_int);
1892 if (len < 0 || len > sizeof(session_key)) {
1893 error("do_connection: bad session key len from %s: "
5ca51e19 1894 "session_key_int %d > sizeof(session_key) %lu",
1895 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
46aa2d1f 1896 rsafail++;
1897 } else {
1898 memset(session_key, 0, sizeof(session_key));
1899 BN_bn2bin(session_key_int,
1900 session_key + sizeof(session_key) - len);
00be5382 1901
8bbf1fa6 1902 derive_ssh1_session_id(
1903 sensitive_data.ssh1_host_key->rsa->n,
1904 sensitive_data.server_key->rsa->n,
1905 cookie, session_id);
00be5382 1906 /*
1907 * Xor the first 16 bytes of the session key with the
1908 * session id.
1909 */
1910 for (i = 0; i < 16; i++)
1911 session_key[i] ^= session_id[i];
46aa2d1f 1912 }
1913 }
1914 if (rsafail) {
00be5382 1915 int bytes = BN_num_bytes(session_key_int);
f6b1ba8f 1916 u_char *buf = xmalloc(bytes);
00be5382 1917 MD5_CTX md;
1918
bbe88b6d 1919 logit("do_connection: generating a fake encryption key");
00be5382 1920 BN_bn2bin(session_key_int, buf);
1921 MD5_Init(&md);
1922 MD5_Update(&md, buf, bytes);
1923 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1924 MD5_Final(session_key, &md);
1925 MD5_Init(&md);
1926 MD5_Update(&md, session_key, 16);
1927 MD5_Update(&md, buf, bytes);
1928 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1929 MD5_Final(session_key + 16, &md);
1930 memset(buf, 0, bytes);
1931 xfree(buf);
0572fe75 1932 for (i = 0; i < 16; i++)
1933 session_id[i] = session_key[i] ^ session_key[i + 16];
46aa2d1f 1934 }
1853d1ef 1935 /* Destroy the private and public keys. No longer. */
63284fbb 1936 destroy_sensitive_data();
00be5382 1937
1853d1ef 1938 if (use_privsep)
1939 mm_ssh1_session_id(session_id);
1940
7b2ea3a1 1941 /* Destroy the decrypted integer. It is no longer needed. */
1942 BN_clear_free(session_key_int);
1943
5260325f 1944 /* Set the session key. From this on all communications will be encrypted. */
1945 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1946
1947 /* Destroy our copy of the session key. It is no longer needed. */
1948 memset(session_key, 0, sizeof(session_key));
1949
1950 debug("Received session key; encryption turned on.");
1951
c242fc96 1952 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
5260325f 1953 packet_start(SSH_SMSG_SUCCESS);
1954 packet_send();
1955 packet_write_wait();
5260325f 1956}
e78a59f5 1957
1958/*
1959 * SSH2 key exchange: diffie-hellman-group1-sha1
1960 */
396c147e 1961static void
1e3b8b07 1962do_ssh2_kex(void)
e78a59f5 1963{
e78a59f5 1964 Kex *kex;
e78a59f5 1965
a8be9f80 1966 if (options.ciphers != NULL) {
6ae2364d 1967 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
a8be9f80 1968 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1969 }
1ad64a93 1970 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1971 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1972 myproposal[PROPOSAL_ENC_ALGS_STOC] =
1973 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1974
b2552997 1975 if (options.macs != NULL) {
1976 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1977 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1978 }
636f76ca 1979 if (!options.compression) {
1980 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1981 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1982 }
fa08c86b 1983 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1984
7a37c112 1985 /* start key exchange */
d8ee838b 1986 kex = kex_setup(myproposal);
98a58eda 1987 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
41e5bd9a 1988 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
98a58eda 1989 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
a5c9ffdb 1990 kex->server = 1;
1991 kex->client_version_string=client_version_string;
1992 kex->server_version_string=server_version_string;
1993 kex->load_host_key=&get_hostkey_by_type;
1853d1ef 1994 kex->host_key_index=&get_hostkey_index;
94ec8c6b 1995
7a37c112 1996 xxx_kex = kex;
1997
c422989b 1998 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
94ec8c6b 1999
d1ac6175 2000 session_id2 = kex->session_id;
2001 session_id2_len = kex->session_id_len;
2002
94ec8c6b 2003#ifdef DEBUG_KEXDH
2004 /* send 1st encrypted/maced/compressed message */
2005 packet_start(SSH2_MSG_IGNORE);
2006 packet_put_cstring("markus");
2007 packet_send();
2008 packet_write_wait();
2009#endif
a5c9ffdb 2010 debug("KEX done");
e78a59f5 2011}
2362db19 2012
2013/* server specific fatal cleanup */
2014void
2015cleanup_exit(int i)
2016{
2017 if (the_authctxt)
2018 do_cleanup(the_authctxt);
2019 _exit(i);
2020}
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