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3c0ef626 | 1 | /* |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * This program is the ssh daemon. It listens for connections from clients, | |
6 | * and performs authentication, executes use commands or shell, and forwards | |
7 | * information to/from the application to the user client over an encrypted | |
8 | * connection. This can also handle forwarding of X11, TCP/IP, and | |
9 | * authentication agent connections. | |
10 | * | |
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: | |
700318f3 | 18 | * Privilege Separation: |
3c0ef626 | 19 | * |
700318f3 | 20 | * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. |
21 | * Copyright (c) 2002 Niels Provos. All rights reserved. | |
3c0ef626 | 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. | |
42 | */ | |
43 | ||
44 | #include "includes.h" | |
12408a1b | 45 | RCSID("$OpenBSD: sshd.c,v 1.284 2003/12/09 21:53:37 markus Exp $"); |
3c0ef626 | 46 | |
47 | #include <openssl/dh.h> | |
48 | #include <openssl/bn.h> | |
e9a17296 | 49 | #include <openssl/md5.h> |
700318f3 | 50 | #include <openssl/rand.h> |
51 | #ifdef HAVE_SECUREWARE | |
52 | #include <sys/security.h> | |
53 | #include <prot.h> | |
54 | #endif | |
3c0ef626 | 55 | |
56 | #include "ssh.h" | |
57 | #include "ssh1.h" | |
58 | #include "ssh2.h" | |
59 | #include "xmalloc.h" | |
60 | #include "rsa.h" | |
61 | #include "sshpty.h" | |
62 | #include "packet.h" | |
63 | #include "mpaux.h" | |
64 | #include "log.h" | |
65 | #include "servconf.h" | |
66 | #include "uidswap.h" | |
67 | #include "compat.h" | |
68 | #include "buffer.h" | |
69 | #include "cipher.h" | |
70 | #include "kex.h" | |
71 | #include "key.h" | |
72 | #include "dh.h" | |
73 | #include "myproposal.h" | |
74 | #include "authfile.h" | |
75 | #include "pathnames.h" | |
76 | #include "atomicio.h" | |
77 | #include "canohost.h" | |
78 | #include "auth.h" | |
79 | #include "misc.h" | |
80 | #include "dispatch.h" | |
81 | #include "channels.h" | |
700318f3 | 82 | #include "session.h" |
83 | #include "monitor_mm.h" | |
84 | #include "monitor.h" | |
85 | #include "monitor_wrap.h" | |
86 | #include "monitor_fdpass.h" | |
3c0ef626 | 87 | |
88 | #ifdef LIBWRAP | |
89 | #include <tcpd.h> | |
90 | #include <syslog.h> | |
91 | int allow_severity = LOG_INFO; | |
92 | int deny_severity = LOG_WARNING; | |
93 | #endif /* LIBWRAP */ | |
94 | ||
95 | #ifndef O_NOCTTY | |
96 | #define O_NOCTTY 0 | |
97 | #endif | |
98 | ||
99 | #ifdef HAVE___PROGNAME | |
100 | extern char *__progname; | |
101 | #else | |
102 | char *__progname; | |
103 | #endif | |
104 | ||
105 | /* Server configuration options. */ | |
106 | ServerOptions options; | |
107 | ||
108 | /* Name of the server configuration file. */ | |
109 | char *config_file_name = _PATH_SERVER_CONFIG_FILE; | |
110 | ||
111 | /* | |
112 | * 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 | */ | |
3c0ef626 | 115 | int IPv4or6 = AF_UNSPEC; |
3c0ef626 | 116 | |
117 | /* | |
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 | */ | |
123 | int debug_flag = 0; | |
124 | ||
125 | /* Flag indicating that the daemon should only test the configuration and keys. */ | |
126 | int test_flag = 0; | |
127 | ||
128 | /* Flag indicating that the daemon is being started from inetd. */ | |
129 | int inetd_flag = 0; | |
130 | ||
131 | /* Flag indicating that sshd should not detach and become a daemon. */ | |
132 | int no_daemon_flag = 0; | |
133 | ||
134 | /* debug goes to stderr unless inetd_flag is set */ | |
135 | int log_stderr = 0; | |
136 | ||
137 | /* Saved arguments to main(). */ | |
138 | char **saved_argv; | |
139 | int saved_argc; | |
140 | ||
141 | /* | |
142 | * The sockets that the server is listening; this is used in the SIGHUP | |
143 | * signal handler. | |
144 | */ | |
145 | #define MAX_LISTEN_SOCKS 16 | |
146 | int listen_socks[MAX_LISTEN_SOCKS]; | |
147 | int num_listen_socks = 0; | |
148 | ||
149 | /* | |
150 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
151 | * sshd will skip the version-number exchange | |
152 | */ | |
153 | char *client_version_string = NULL; | |
154 | char *server_version_string = NULL; | |
155 | ||
156 | /* for rekeying XXX fixme */ | |
157 | Kex *xxx_kex; | |
158 | ||
159 | /* | |
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 | */ | |
167 | struct { | |
168 | Key *server_key; /* ephemeral server key */ | |
169 | 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; | |
173 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; | |
174 | } sensitive_data; | |
175 | ||
176 | /* | |
177 | * 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. | |
179 | */ | |
e9a17296 | 180 | static volatile sig_atomic_t key_do_regen = 0; |
3c0ef626 | 181 | |
182 | /* This is set to true when a signal is received. */ | |
e9a17296 | 183 | static volatile sig_atomic_t received_sighup = 0; |
184 | static volatile sig_atomic_t received_sigterm = 0; | |
3c0ef626 | 185 | |
186 | /* session identifier, used by RSA-auth */ | |
187 | u_char session_id[16]; | |
188 | ||
189 | /* same for ssh2 */ | |
190 | u_char *session_id2 = NULL; | |
0fff78ff | 191 | u_int session_id2_len = 0; |
3c0ef626 | 192 | |
193 | /* record remote hostname or ip */ | |
194 | u_int utmp_len = MAXHOSTNAMELEN; | |
195 | ||
e9a17296 | 196 | /* options.max_startup sized array of fd ints */ |
197 | int *startup_pipes = NULL; | |
198 | int startup_pipe; /* in child */ | |
199 | ||
700318f3 | 200 | /* variables used for privilege separation */ |
6a9b3198 | 201 | int use_privsep; |
202 | struct monitor *pmonitor; | |
700318f3 | 203 | |
0fff78ff | 204 | /* message to be displayed after login */ |
205 | Buffer loginmsg; | |
206 | ||
12408a1b | 207 | /* global authentication context */ |
208 | Authctxt *the_authctxt = NULL; | |
209 | ||
3c0ef626 | 210 | /* Prototypes for various functions defined later in this file. */ |
211 | void destroy_sensitive_data(void); | |
700318f3 | 212 | void demote_sensitive_data(void); |
3c0ef626 | 213 | |
214 | static void do_ssh1_kex(void); | |
215 | static void do_ssh2_kex(void); | |
216 | ||
217 | /* | |
218 | * Close all listening sockets | |
219 | */ | |
220 | static void | |
221 | close_listen_socks(void) | |
222 | { | |
223 | int i; | |
680cee3b | 224 | |
3c0ef626 | 225 | for (i = 0; i < num_listen_socks; i++) |
226 | close(listen_socks[i]); | |
227 | num_listen_socks = -1; | |
228 | } | |
229 | ||
e9a17296 | 230 | static void |
231 | close_startup_pipes(void) | |
232 | { | |
233 | int i; | |
680cee3b | 234 | |
e9a17296 | 235 | 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 | ||
3c0ef626 | 241 | /* |
242 | * 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 | */ | |
246 | static void | |
247 | sighup_handler(int sig) | |
248 | { | |
e9a17296 | 249 | int save_errno = errno; |
250 | ||
3c0ef626 | 251 | received_sighup = 1; |
252 | signal(SIGHUP, sighup_handler); | |
e9a17296 | 253 | errno = save_errno; |
3c0ef626 | 254 | } |
255 | ||
256 | /* | |
257 | * Called from the main program after receiving SIGHUP. | |
258 | * Restarts the server. | |
259 | */ | |
260 | static void | |
261 | sighup_restart(void) | |
262 | { | |
0fff78ff | 263 | logit("Received SIGHUP; restarting."); |
3c0ef626 | 264 | close_listen_socks(); |
e9a17296 | 265 | close_startup_pipes(); |
3c0ef626 | 266 | execv(saved_argv[0], saved_argv); |
0fff78ff | 267 | logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], |
680cee3b | 268 | strerror(errno)); |
3c0ef626 | 269 | exit(1); |
270 | } | |
271 | ||
272 | /* | |
273 | * Generic signal handler for terminating signals in the master daemon. | |
274 | */ | |
275 | static void | |
276 | sigterm_handler(int sig) | |
277 | { | |
278 | received_sigterm = sig; | |
279 | } | |
280 | ||
281 | /* | |
282 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
283 | * reap any zombies left by exited children. | |
284 | */ | |
285 | static void | |
286 | main_sigchld_handler(int sig) | |
287 | { | |
288 | int save_errno = errno; | |
680cee3b | 289 | pid_t pid; |
3c0ef626 | 290 | int status; |
291 | ||
700318f3 | 292 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || |
293 | (pid < 0 && errno == EINTR)) | |
3c0ef626 | 294 | ; |
295 | ||
296 | signal(SIGCHLD, main_sigchld_handler); | |
297 | errno = save_errno; | |
298 | } | |
299 | ||
300 | /* | |
301 | * Signal handler for the alarm after the login grace period has expired. | |
302 | */ | |
303 | static void | |
304 | grace_alarm_handler(int sig) | |
305 | { | |
306 | /* XXX no idea how fix this signal handler */ | |
307 | ||
3c0ef626 | 308 | /* Log error and exit. */ |
41b2f314 | 309 | fatal("Timeout before authentication for %s", get_remote_ipaddr()); |
3c0ef626 | 310 | } |
311 | ||
312 | /* | |
313 | * 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 | */ | |
319 | static void | |
320 | generate_ephemeral_server_key(void) | |
321 | { | |
41b2f314 | 322 | u_int32_t rnd = 0; |
3c0ef626 | 323 | int i; |
324 | ||
325 | verbose("Generating %s%d bit RSA key.", | |
326 | sensitive_data.server_key ? "new " : "", options.server_key_bits); | |
327 | if (sensitive_data.server_key != NULL) | |
328 | key_free(sensitive_data.server_key); | |
329 | sensitive_data.server_key = key_generate(KEY_RSA1, | |
330 | options.server_key_bits); | |
331 | verbose("RSA key generation complete."); | |
332 | ||
333 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
334 | if (i % 4 == 0) | |
41b2f314 | 335 | rnd = arc4random(); |
336 | sensitive_data.ssh1_cookie[i] = rnd & 0xff; | |
337 | rnd >>= 8; | |
3c0ef626 | 338 | } |
339 | arc4random_stir(); | |
340 | } | |
341 | ||
342 | static void | |
343 | key_regeneration_alarm(int sig) | |
344 | { | |
345 | int save_errno = errno; | |
680cee3b | 346 | |
3c0ef626 | 347 | signal(SIGALRM, SIG_DFL); |
348 | errno = save_errno; | |
349 | key_do_regen = 1; | |
350 | } | |
351 | ||
352 | static void | |
353 | sshd_exchange_identification(int sock_in, int sock_out) | |
354 | { | |
355 | int i, mismatch; | |
356 | int remote_major, remote_minor; | |
357 | int major, minor; | |
358 | 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 | ||
362 | 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); | |
374 | server_version_string = xstrdup(buf); | |
375 | ||
0fff78ff | 376 | /* 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()); | |
12408a1b | 381 | cleanup_exit(255); |
0fff78ff | 382 | } |
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()); | |
12408a1b | 390 | cleanup_exit(255); |
3c0ef626 | 391 | } |
0fff78ff | 392 | 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) | |
3c0ef626 | 397 | break; |
0fff78ff | 398 | continue; |
399 | } | |
400 | if (buf[i] == '\n') { | |
401 | buf[i] = 0; | |
402 | break; | |
3c0ef626 | 403 | } |
3c0ef626 | 404 | } |
0fff78ff | 405 | buf[sizeof(buf) - 1] = 0; |
406 | client_version_string = xstrdup(buf); | |
3c0ef626 | 407 | |
408 | /* | |
409 | * Check that the versions match. In future this might accept | |
410 | * several versions and set appropriate flags to handle them. | |
411 | */ | |
412 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
413 | &remote_major, &remote_minor, remote_version) != 3) { | |
414 | s = "Protocol mismatch.\n"; | |
0fff78ff | 415 | (void) atomicio(vwrite, sock_out, s, strlen(s)); |
3c0ef626 | 416 | close(sock_in); |
417 | close(sock_out); | |
0fff78ff | 418 | logit("Bad protocol version identification '%.100s' from %s", |
3c0ef626 | 419 | client_version_string, get_remote_ipaddr()); |
12408a1b | 420 | cleanup_exit(255); |
3c0ef626 | 421 | } |
422 | debug("Client protocol version %d.%d; client software version %.100s", | |
e9a17296 | 423 | remote_major, remote_minor, remote_version); |
3c0ef626 | 424 | |
425 | compat_datafellows(remote_version); | |
426 | ||
41b2f314 | 427 | if (datafellows & SSH_BUG_PROBE) { |
0fff78ff | 428 | logit("probed from %s with %s. Don't panic.", |
41b2f314 | 429 | get_remote_ipaddr(), client_version_string); |
12408a1b | 430 | cleanup_exit(255); |
41b2f314 | 431 | } |
432 | ||
3c0ef626 | 433 | if (datafellows & SSH_BUG_SCANNER) { |
0fff78ff | 434 | logit("scanned from %s with %s. Don't panic.", |
3c0ef626 | 435 | get_remote_ipaddr(), client_version_string); |
12408a1b | 436 | cleanup_exit(255); |
3c0ef626 | 437 | } |
438 | ||
439 | mismatch = 0; | |
e9a17296 | 440 | switch (remote_major) { |
3c0ef626 | 441 | case 1: |
442 | if (remote_minor == 99) { | |
443 | if (options.protocol & SSH_PROTO_2) | |
444 | enable_compat20(); | |
445 | else | |
446 | mismatch = 1; | |
447 | break; | |
448 | } | |
449 | if (!(options.protocol & SSH_PROTO_1)) { | |
450 | mismatch = 1; | |
451 | break; | |
452 | } | |
453 | if (remote_minor < 3) { | |
454 | packet_disconnect("Your ssh version is too old and " | |
455 | "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 | } | |
460 | break; | |
461 | case 2: | |
462 | if (options.protocol & SSH_PROTO_2) { | |
463 | enable_compat20(); | |
464 | break; | |
465 | } | |
466 | /* FALLTHROUGH */ | |
467 | default: | |
468 | mismatch = 1; | |
469 | break; | |
470 | } | |
471 | chop(server_version_string); | |
472 | debug("Local version string %.200s", server_version_string); | |
473 | ||
474 | if (mismatch) { | |
475 | s = "Protocol major versions differ.\n"; | |
0fff78ff | 476 | (void) atomicio(vwrite, sock_out, s, strlen(s)); |
3c0ef626 | 477 | close(sock_in); |
478 | close(sock_out); | |
0fff78ff | 479 | logit("Protocol major versions differ for %s: %.200s vs. %.200s", |
3c0ef626 | 480 | get_remote_ipaddr(), |
481 | server_version_string, client_version_string); | |
12408a1b | 482 | cleanup_exit(255); |
3c0ef626 | 483 | } |
484 | } | |
485 | ||
3c0ef626 | 486 | /* Destroy the host and server keys. They will no longer be needed. */ |
487 | void | |
488 | destroy_sensitive_data(void) | |
489 | { | |
490 | int i; | |
491 | ||
492 | if (sensitive_data.server_key) { | |
493 | key_free(sensitive_data.server_key); | |
494 | sensitive_data.server_key = NULL; | |
495 | } | |
e9a17296 | 496 | for (i = 0; i < options.num_host_key_files; i++) { |
3c0ef626 | 497 | 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; | |
503 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); | |
504 | } | |
505 | ||
700318f3 | 506 | /* Demote private to public keys for network child */ |
507 | void | |
508 | demote_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 | ||
532 | static void | |
533 | privsep_preauth_child(void) | |
534 | { | |
41b2f314 | 535 | u_int32_t rnd[256]; |
536 | gid_t gidset[1]; | |
700318f3 | 537 | struct passwd *pw; |
680cee3b | 538 | int i; |
700318f3 | 539 | |
540 | /* Enable challenge-response authentication for privilege separation */ | |
541 | privsep_challenge_enable(); | |
542 | ||
543 | for (i = 0; i < 256; i++) | |
41b2f314 | 544 | rnd[i] = arc4random(); |
545 | RAND_seed(rnd, sizeof(rnd)); | |
700318f3 | 546 | |
547 | /* Demote the private keys to public keys. */ | |
548 | demote_sensitive_data(); | |
549 | ||
550 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
551 | fatal("Privilege separation user %s does not exist", | |
552 | SSH_PRIVSEP_USER); | |
553 | memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); | |
554 | endpwent(); | |
555 | ||
41b2f314 | 556 | /* Change our root directory */ |
700318f3 | 557 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) |
558 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
559 | strerror(errno)); | |
560 | if (chdir("/") == -1) | |
561 | fatal("chdir(\"/\"): %s", strerror(errno)); | |
562 | ||
563 | /* Drop our privileges */ | |
564 | debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, | |
565 | (u_int)pw->pw_gid); | |
680cee3b | 566 | #if 0 |
567 | /* XXX not ready, to heavy after chroot */ | |
700318f3 | 568 | do_setusercontext(pw); |
680cee3b | 569 | #else |
570 | gidset[0] = pw->pw_gid; | |
680cee3b | 571 | if (setgroups(1, gidset) < 0) |
572 | fatal("setgroups: %.100s", strerror(errno)); | |
573 | permanently_set_uid(pw); | |
574 | #endif | |
700318f3 | 575 | } |
576 | ||
12408a1b | 577 | static int |
578 | privsep_preauth(Authctxt *authctxt) | |
700318f3 | 579 | { |
700318f3 | 580 | int status; |
581 | pid_t pid; | |
582 | ||
583 | /* Set up unprivileged child process to deal with network data */ | |
584 | pmonitor = monitor_init(); | |
585 | /* Store a pointer to the kex for later rekeying */ | |
586 | pmonitor->m_pkex = &xxx_kex; | |
587 | ||
588 | pid = fork(); | |
589 | if (pid == -1) { | |
590 | fatal("fork of unprivileged child failed"); | |
591 | } else if (pid != 0) { | |
f5799ae1 | 592 | debug2("Network child is on pid %ld", (long)pid); |
700318f3 | 593 | |
594 | close(pmonitor->m_recvfd); | |
12408a1b | 595 | monitor_child_preauth(authctxt, pmonitor); |
700318f3 | 596 | close(pmonitor->m_sendfd); |
597 | ||
598 | /* Sync memory */ | |
599 | monitor_sync(pmonitor); | |
600 | ||
601 | /* Wait for the child's exit status */ | |
602 | while (waitpid(pid, &status, 0) < 0) | |
603 | if (errno != EINTR) | |
604 | break; | |
12408a1b | 605 | return (1); |
700318f3 | 606 | } else { |
607 | /* child */ | |
608 | ||
609 | close(pmonitor->m_sendfd); | |
610 | ||
611 | /* Demote the child */ | |
612 | if (getuid() == 0 || geteuid() == 0) | |
613 | privsep_preauth_child(); | |
614 | setproctitle("%s", "[net]"); | |
615 | } | |
12408a1b | 616 | return (0); |
700318f3 | 617 | } |
618 | ||
619 | static void | |
620 | privsep_postauth(Authctxt *authctxt) | |
621 | { | |
41b2f314 | 622 | #ifdef DISABLE_FD_PASSING |
680cee3b | 623 | if (1) { |
624 | #else | |
700318f3 | 625 | if (authctxt->pw->pw_uid == 0 || options.use_login) { |
680cee3b | 626 | #endif |
700318f3 | 627 | /* File descriptor passing is broken or root login */ |
628 | monitor_apply_keystate(pmonitor); | |
629 | use_privsep = 0; | |
630 | return; | |
631 | } | |
632 | ||
633 | /* Authentication complete */ | |
634 | alarm(0); | |
635 | if (startup_pipe != -1) { | |
636 | close(startup_pipe); | |
637 | startup_pipe = -1; | |
638 | } | |
639 | ||
640 | /* New socket pair */ | |
641 | monitor_reinit(pmonitor); | |
642 | ||
643 | pmonitor->m_pid = fork(); | |
644 | if (pmonitor->m_pid == -1) | |
645 | fatal("fork of unprivileged child failed"); | |
646 | else if (pmonitor->m_pid != 0) { | |
f5799ae1 | 647 | debug2("User child is on pid %ld", (long)pmonitor->m_pid); |
700318f3 | 648 | close(pmonitor->m_recvfd); |
649 | monitor_child_postauth(pmonitor); | |
650 | ||
651 | /* NEVERREACHED */ | |
652 | exit(0); | |
653 | } | |
654 | ||
655 | close(pmonitor->m_sendfd); | |
656 | ||
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 */ | |
664 | monitor_apply_keystate(pmonitor); | |
665 | } | |
666 | ||
3c0ef626 | 667 | static char * |
668 | list_hostkey_types(void) | |
669 | { | |
e9a17296 | 670 | Buffer b; |
12408a1b | 671 | const char *p; |
672 | char *ret; | |
3c0ef626 | 673 | int i; |
e9a17296 | 674 | |
675 | buffer_init(&b); | |
676 | for (i = 0; i < options.num_host_key_files; i++) { | |
3c0ef626 | 677 | Key *key = sensitive_data.host_keys[i]; |
678 | if (key == NULL) | |
679 | continue; | |
e9a17296 | 680 | switch (key->type) { |
3c0ef626 | 681 | case KEY_RSA: |
682 | case KEY_DSA: | |
e9a17296 | 683 | if (buffer_len(&b) > 0) |
684 | buffer_append(&b, ",", 1); | |
685 | p = key_ssh_name(key); | |
686 | buffer_append(&b, p, strlen(p)); | |
3c0ef626 | 687 | break; |
688 | } | |
689 | } | |
e9a17296 | 690 | buffer_append(&b, "\0", 1); |
12408a1b | 691 | ret = xstrdup(buffer_ptr(&b)); |
e9a17296 | 692 | buffer_free(&b); |
12408a1b | 693 | debug("list_hostkey_types: %s", ret); |
694 | return ret; | |
3c0ef626 | 695 | } |
696 | ||
700318f3 | 697 | Key * |
3c0ef626 | 698 | get_hostkey_by_type(int type) |
699 | { | |
700 | int i; | |
680cee3b | 701 | |
e9a17296 | 702 | for (i = 0; i < options.num_host_key_files; i++) { |
3c0ef626 | 703 | Key *key = sensitive_data.host_keys[i]; |
704 | if (key != NULL && key->type == type) | |
705 | return key; | |
706 | } | |
707 | return NULL; | |
708 | } | |
709 | ||
700318f3 | 710 | Key * |
711 | get_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 | ||
718 | int | |
719 | get_hostkey_index(Key *key) | |
720 | { | |
721 | int i; | |
680cee3b | 722 | |
700318f3 | 723 | 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 | ||
3c0ef626 | 730 | /* |
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 | */ | |
736 | static int | |
737 | drop_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 | ||
e9a17296 | 759 | static void |
760 | usage(void) | |
761 | { | |
12408a1b | 762 | fprintf(stderr, "sshd version %s, %s\n", |
763 | SSH_VERSION, SSLeay_version(SSLEAY_VERSION)); | |
e9a17296 | 764 | 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 | } | |
3c0ef626 | 784 | |
785 | /* | |
786 | * Main program for the daemon. | |
787 | */ | |
788 | int | |
789 | main(int ac, char **av) | |
790 | { | |
791 | extern char *optarg; | |
792 | extern int optind; | |
793 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; | |
794 | pid_t pid; | |
795 | socklen_t fromlen; | |
796 | fd_set *fdset; | |
797 | struct sockaddr_storage from; | |
798 | const char *remote_ip; | |
799 | int remote_port; | |
800 | FILE *f; | |
3c0ef626 | 801 | struct addrinfo *ai; |
802 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
12408a1b | 803 | char *line; |
3c0ef626 | 804 | int listen_sock, maxfd; |
805 | int startup_p[2]; | |
806 | int startups = 0; | |
807 | Key *key; | |
12408a1b | 808 | Authctxt *authctxt; |
3c0ef626 | 809 | int ret, key_used = 0; |
810 | ||
700318f3 | 811 | #ifdef HAVE_SECUREWARE |
812 | (void)set_auth_parameters(ac, av); | |
813 | #endif | |
0fff78ff | 814 | __progname = ssh_get_progname(av[0]); |
3c0ef626 | 815 | init_rng(); |
816 | ||
6a9b3198 | 817 | /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ |
3c0ef626 | 818 | saved_argc = ac; |
0fff78ff | 819 | saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1)); |
6a9b3198 | 820 | for (i = 0; i < ac; i++) |
821 | saved_argv[i] = xstrdup(av[i]); | |
0fff78ff | 822 | saved_argv[i] = NULL; |
6a9b3198 | 823 | |
824 | #ifndef HAVE_SETPROCTITLE | |
825 | /* Prepare for later setproctitle emulation */ | |
826 | compat_init_setproctitle(ac, av); | |
0fff78ff | 827 | av = saved_argv; |
6a9b3198 | 828 | #endif |
3c0ef626 | 829 | |
830 | /* Initialize configuration options to their default values. */ | |
831 | initialize_server_options(&options); | |
832 | ||
833 | /* Parse command-line arguments. */ | |
0fff78ff | 834 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqtQ46")) != -1) { |
3c0ef626 | 835 | switch (opt) { |
836 | case '4': | |
837 | IPv4or6 = AF_INET; | |
838 | break; | |
839 | case '6': | |
840 | IPv4or6 = AF_INET6; | |
841 | break; | |
842 | case 'f': | |
843 | config_file_name = optarg; | |
844 | break; | |
845 | case 'd': | |
0fff78ff | 846 | if (debug_flag == 0) { |
3c0ef626 | 847 | debug_flag = 1; |
848 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
0fff78ff | 849 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) |
3c0ef626 | 850 | options.log_level++; |
3c0ef626 | 851 | break; |
852 | case 'D': | |
853 | no_daemon_flag = 1; | |
854 | break; | |
855 | case 'e': | |
856 | log_stderr = 1; | |
857 | break; | |
858 | case 'i': | |
859 | inetd_flag = 1; | |
860 | break; | |
861 | case 'Q': | |
862 | /* ignored */ | |
863 | break; | |
864 | case 'q': | |
865 | options.log_level = SYSLOG_LEVEL_QUIET; | |
866 | break; | |
867 | case 'b': | |
868 | options.server_key_bits = atoi(optarg); | |
869 | break; | |
870 | case 'p': | |
871 | options.ports_from_cmdline = 1; | |
872 | if (options.num_ports >= MAX_PORTS) { | |
873 | fprintf(stderr, "too many ports.\n"); | |
874 | exit(1); | |
875 | } | |
876 | options.ports[options.num_ports++] = a2port(optarg); | |
877 | if (options.ports[options.num_ports-1] == 0) { | |
878 | fprintf(stderr, "Bad port number.\n"); | |
879 | exit(1); | |
880 | } | |
881 | break; | |
882 | case 'g': | |
883 | if ((options.login_grace_time = convtime(optarg)) == -1) { | |
884 | fprintf(stderr, "Invalid login grace time.\n"); | |
885 | exit(1); | |
886 | } | |
887 | break; | |
888 | case 'k': | |
889 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { | |
890 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
891 | exit(1); | |
892 | } | |
893 | break; | |
894 | case 'h': | |
895 | if (options.num_host_key_files >= MAX_HOSTKEYS) { | |
896 | fprintf(stderr, "too many host keys.\n"); | |
897 | exit(1); | |
898 | } | |
899 | options.host_key_files[options.num_host_key_files++] = optarg; | |
900 | break; | |
3c0ef626 | 901 | case 't': |
902 | test_flag = 1; | |
903 | break; | |
904 | case 'u': | |
905 | utmp_len = atoi(optarg); | |
41b2f314 | 906 | if (utmp_len > MAXHOSTNAMELEN) { |
907 | fprintf(stderr, "Invalid utmp length.\n"); | |
908 | exit(1); | |
909 | } | |
3c0ef626 | 910 | break; |
e9a17296 | 911 | case 'o': |
12408a1b | 912 | line = xstrdup(optarg); |
913 | if (process_server_config_line(&options, line, | |
e9a17296 | 914 | "command-line", 0) != 0) |
915 | exit(1); | |
12408a1b | 916 | xfree(line); |
e9a17296 | 917 | break; |
3c0ef626 | 918 | case '?': |
919 | default: | |
e9a17296 | 920 | usage(); |
921 | break; | |
3c0ef626 | 922 | } |
923 | } | |
924 | SSLeay_add_all_algorithms(); | |
925 | channel_set_af(IPv4or6); | |
926 | ||
927 | /* | |
928 | * Force logging to stderr until we have loaded the private host | |
929 | * key (unless started from inetd) | |
930 | */ | |
931 | log_init(__progname, | |
e9a17296 | 932 | options.log_level == SYSLOG_LEVEL_NOT_SET ? |
933 | SYSLOG_LEVEL_INFO : options.log_level, | |
934 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
935 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
6a9b3198 | 936 | log_stderr || !inetd_flag); |
3c0ef626 | 937 | |
41b2f314 | 938 | #ifdef _UNICOS |
3c0ef626 | 939 | /* Cray can define user privs drop all prives now! |
940 | * Not needed on PRIV_SU systems! | |
941 | */ | |
942 | drop_cray_privs(); | |
943 | #endif | |
944 | ||
945 | seed_rng(); | |
946 | ||
947 | /* Read server configuration options from the configuration file. */ | |
948 | read_server_config(&options, config_file_name); | |
949 | ||
950 | /* Fill in default values for those options not explicitly set. */ | |
951 | fill_default_server_options(&options); | |
952 | ||
953 | /* Check that there are no remaining arguments. */ | |
954 | if (optind < ac) { | |
955 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
956 | exit(1); | |
957 | } | |
958 | ||
959 | debug("sshd version %.100s", SSH_VERSION); | |
960 | ||
961 | /* load private host keys */ | |
41b2f314 | 962 | sensitive_data.host_keys = xmalloc(options.num_host_key_files * |
963 | sizeof(Key *)); | |
e9a17296 | 964 | for (i = 0; i < options.num_host_key_files; i++) |
3c0ef626 | 965 | sensitive_data.host_keys[i] = NULL; |
966 | sensitive_data.server_key = NULL; | |
967 | sensitive_data.ssh1_host_key = NULL; | |
968 | sensitive_data.have_ssh1_key = 0; | |
969 | sensitive_data.have_ssh2_key = 0; | |
970 | ||
e9a17296 | 971 | for (i = 0; i < options.num_host_key_files; i++) { |
3c0ef626 | 972 | key = key_load_private(options.host_key_files[i], "", NULL); |
973 | sensitive_data.host_keys[i] = key; | |
974 | if (key == NULL) { | |
975 | error("Could not load host key: %s", | |
976 | options.host_key_files[i]); | |
977 | sensitive_data.host_keys[i] = NULL; | |
978 | continue; | |
979 | } | |
e9a17296 | 980 | switch (key->type) { |
3c0ef626 | 981 | case KEY_RSA1: |
982 | sensitive_data.ssh1_host_key = key; | |
983 | sensitive_data.have_ssh1_key = 1; | |
984 | break; | |
985 | case KEY_RSA: | |
986 | case KEY_DSA: | |
987 | sensitive_data.have_ssh2_key = 1; | |
988 | break; | |
989 | } | |
990 | debug("private host key: #%d type %d %s", i, key->type, | |
991 | key_type(key)); | |
992 | } | |
993 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
0fff78ff | 994 | logit("Disabling protocol version 1. Could not load host key"); |
3c0ef626 | 995 | options.protocol &= ~SSH_PROTO_1; |
996 | } | |
997 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
0fff78ff | 998 | logit("Disabling protocol version 2. Could not load host key"); |
3c0ef626 | 999 | options.protocol &= ~SSH_PROTO_2; |
1000 | } | |
1001 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { | |
0fff78ff | 1002 | logit("sshd: no hostkeys available -- exiting."); |
3c0ef626 | 1003 | exit(1); |
1004 | } | |
1005 | ||
1006 | /* Check certain values for sanity. */ | |
1007 | if (options.protocol & SSH_PROTO_1) { | |
1008 | if (options.server_key_bits < 512 || | |
1009 | options.server_key_bits > 32768) { | |
1010 | fprintf(stderr, "Bad server key size.\n"); | |
1011 | exit(1); | |
1012 | } | |
1013 | /* | |
1014 | * Check that server and host key lengths differ sufficiently. This | |
1015 | * is necessary to make double encryption work with rsaref. Oh, I | |
1016 | * hate software patents. I dont know if this can go? Niels | |
1017 | */ | |
1018 | if (options.server_key_bits > | |
680cee3b | 1019 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - |
1020 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1021 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1022 | SSH_KEY_BITS_RESERVED) { | |
3c0ef626 | 1023 | options.server_key_bits = |
680cee3b | 1024 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
1025 | SSH_KEY_BITS_RESERVED; | |
3c0ef626 | 1026 | debug("Forcing server key to %d bits to make it differ from host key.", |
1027 | options.server_key_bits); | |
1028 | } | |
1029 | } | |
1030 | ||
f5799ae1 | 1031 | if (use_privsep) { |
1032 | struct passwd *pw; | |
1033 | struct stat st; | |
1034 | ||
1035 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
1036 | fatal("Privilege separation user %s does not exist", | |
1037 | SSH_PRIVSEP_USER); | |
1038 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1039 | (S_ISDIR(st.st_mode) == 0)) | |
1040 | fatal("Missing privilege separation directory: %s", | |
1041 | _PATH_PRIVSEP_CHROOT_DIR); | |
41b2f314 | 1042 | |
1043 | #ifdef HAVE_CYGWIN | |
1044 | if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && | |
1045 | (st.st_uid != getuid () || | |
1046 | (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) | |
1047 | #else | |
680cee3b | 1048 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) |
41b2f314 | 1049 | #endif |
6a9b3198 | 1050 | fatal("%s must be owned by root and not group or " |
1051 | "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); | |
f5799ae1 | 1052 | } |
1053 | ||
3c0ef626 | 1054 | /* Configuration looks good, so exit if in test mode. */ |
1055 | if (test_flag) | |
1056 | exit(0); | |
1057 | ||
700318f3 | 1058 | /* |
1059 | * Clear out any supplemental groups we may have inherited. This | |
1060 | * prevents inadvertent creation of files with bad modes (in the | |
12408a1b | 1061 | * portable version at least, it's certainly possible for PAM |
1062 | * to create a file, and we can't control the code in every | |
700318f3 | 1063 | * module which might be used). |
1064 | */ | |
1065 | if (setgroups(0, NULL) < 0) | |
1066 | debug("setgroups() failed: %.200s", strerror(errno)); | |
3c0ef626 | 1067 | |
1068 | /* Initialize the log (it is reinitialized below in case we forked). */ | |
1069 | if (debug_flag && !inetd_flag) | |
1070 | log_stderr = 1; | |
1071 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1072 | ||
1073 | /* | |
1074 | * If not in debugging mode, and not started from inetd, disconnect | |
1075 | * from the controlling terminal, and fork. The original process | |
1076 | * exits. | |
1077 | */ | |
1078 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { | |
1079 | #ifdef TIOCNOTTY | |
1080 | int fd; | |
1081 | #endif /* TIOCNOTTY */ | |
1082 | if (daemon(0, 0) < 0) | |
1083 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1084 | ||
1085 | /* Disconnect from the controlling tty. */ | |
1086 | #ifdef TIOCNOTTY | |
1087 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
1088 | if (fd >= 0) { | |
1089 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1090 | close(fd); | |
1091 | } | |
1092 | #endif /* TIOCNOTTY */ | |
1093 | } | |
1094 | /* Reinitialize the log (because of the fork above). */ | |
1095 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1096 | ||
1097 | /* Initialize the random number generator. */ | |
1098 | arc4random_stir(); | |
1099 | ||
1100 | /* Chdir to the root directory so that the current disk can be | |
1101 | unmounted if desired. */ | |
1102 | chdir("/"); | |
e9a17296 | 1103 | |
3c0ef626 | 1104 | /* ignore SIGPIPE */ |
1105 | signal(SIGPIPE, SIG_IGN); | |
1106 | ||
1107 | /* Start listening for a socket, unless started from inetd. */ | |
1108 | if (inetd_flag) { | |
1109 | int s1; | |
1110 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
1111 | dup(s1); | |
1112 | sock_in = dup(0); | |
1113 | sock_out = dup(1); | |
1114 | startup_pipe = -1; | |
1115 | /* | |
1116 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1117 | * as our code for setting the descriptors won\'t work if | |
1118 | * ttyfd happens to be one of those. | |
1119 | */ | |
1120 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); | |
1121 | if (options.protocol & SSH_PROTO_1) | |
1122 | generate_ephemeral_server_key(); | |
1123 | } else { | |
1124 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { | |
1125 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1126 | continue; | |
1127 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1128 | fatal("Too many listen sockets. " | |
1129 | "Enlarge MAX_LISTEN_SOCKS"); | |
1130 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1131 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1132 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
1133 | error("getnameinfo failed"); | |
1134 | continue; | |
1135 | } | |
1136 | /* Create socket for listening. */ | |
0fff78ff | 1137 | listen_sock = socket(ai->ai_family, ai->ai_socktype, |
1138 | ai->ai_protocol); | |
3c0ef626 | 1139 | if (listen_sock < 0) { |
1140 | /* kernel may not support ipv6 */ | |
1141 | verbose("socket: %.100s", strerror(errno)); | |
1142 | continue; | |
1143 | } | |
3c0ef626 | 1144 | /* |
41b2f314 | 1145 | * Set socket options. |
1146 | * Allow local port reuse in TIME_WAIT. | |
3c0ef626 | 1147 | */ |
41b2f314 | 1148 | if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, |
1149 | &on, sizeof(on)) == -1) | |
1150 | error("setsockopt SO_REUSEADDR: %s", strerror(errno)); | |
3c0ef626 | 1151 | |
1152 | debug("Bind to port %s on %s.", strport, ntop); | |
1153 | ||
1154 | /* Bind the socket to the desired port. */ | |
1155 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { | |
1156 | if (!ai->ai_next) | |
1157 | error("Bind to port %s on %s failed: %.200s.", | |
1158 | strport, ntop, strerror(errno)); | |
1159 | close(listen_sock); | |
1160 | continue; | |
1161 | } | |
1162 | listen_socks[num_listen_socks] = listen_sock; | |
1163 | num_listen_socks++; | |
1164 | ||
1165 | /* Start listening on the port. */ | |
0fff78ff | 1166 | logit("Server listening on %s port %s.", ntop, strport); |
12408a1b | 1167 | if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) |
3c0ef626 | 1168 | fatal("listen: %.100s", strerror(errno)); |
1169 | ||
1170 | } | |
1171 | freeaddrinfo(options.listen_addrs); | |
1172 | ||
1173 | if (!num_listen_socks) | |
1174 | fatal("Cannot bind any address."); | |
1175 | ||
1176 | if (options.protocol & SSH_PROTO_1) | |
1177 | generate_ephemeral_server_key(); | |
1178 | ||
1179 | /* | |
1180 | * Arrange to restart on SIGHUP. The handler needs | |
1181 | * listen_sock. | |
1182 | */ | |
1183 | signal(SIGHUP, sighup_handler); | |
1184 | ||
1185 | signal(SIGTERM, sigterm_handler); | |
1186 | signal(SIGQUIT, sigterm_handler); | |
1187 | ||
1188 | /* Arrange SIGCHLD to be caught. */ | |
1189 | signal(SIGCHLD, main_sigchld_handler); | |
1190 | ||
1191 | /* Write out the pid file after the sigterm handler is setup */ | |
1192 | if (!debug_flag) { | |
1193 | /* | |
1194 | * Record our pid in /var/run/sshd.pid to make it | |
1195 | * easier to kill the correct sshd. We don't want to | |
1196 | * do this before the bind above because the bind will | |
1197 | * fail if there already is a daemon, and this will | |
1198 | * overwrite any old pid in the file. | |
1199 | */ | |
1200 | f = fopen(options.pid_file, "wb"); | |
0fff78ff | 1201 | if (f == NULL) { |
1202 | error("Couldn't create pid file \"%s\": %s", | |
1203 | options.pid_file, strerror(errno)); | |
1204 | } else { | |
f5799ae1 | 1205 | fprintf(f, "%ld\n", (long) getpid()); |
3c0ef626 | 1206 | fclose(f); |
1207 | } | |
1208 | } | |
1209 | ||
1210 | /* setup fd set for listen */ | |
1211 | fdset = NULL; | |
1212 | maxfd = 0; | |
1213 | for (i = 0; i < num_listen_socks; i++) | |
1214 | if (listen_socks[i] > maxfd) | |
1215 | maxfd = listen_socks[i]; | |
1216 | /* pipes connected to unauthenticated childs */ | |
1217 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1218 | for (i = 0; i < options.max_startups; i++) | |
1219 | startup_pipes[i] = -1; | |
1220 | ||
1221 | /* | |
1222 | * Stay listening for connections until the system crashes or | |
1223 | * the daemon is killed with a signal. | |
1224 | */ | |
1225 | for (;;) { | |
1226 | if (received_sighup) | |
1227 | sighup_restart(); | |
1228 | if (fdset != NULL) | |
1229 | xfree(fdset); | |
1230 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); | |
1231 | fdset = (fd_set *)xmalloc(fdsetsz); | |
1232 | memset(fdset, 0, fdsetsz); | |
1233 | ||
1234 | for (i = 0; i < num_listen_socks; i++) | |
1235 | FD_SET(listen_socks[i], fdset); | |
1236 | for (i = 0; i < options.max_startups; i++) | |
1237 | if (startup_pipes[i] != -1) | |
1238 | FD_SET(startup_pipes[i], fdset); | |
1239 | ||
1240 | /* Wait in select until there is a connection. */ | |
1241 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); | |
1242 | if (ret < 0 && errno != EINTR) | |
1243 | error("select: %.100s", strerror(errno)); | |
1244 | if (received_sigterm) { | |
0fff78ff | 1245 | logit("Received signal %d; terminating.", |
e9a17296 | 1246 | (int) received_sigterm); |
3c0ef626 | 1247 | close_listen_socks(); |
1248 | unlink(options.pid_file); | |
1249 | exit(255); | |
1250 | } | |
1251 | if (key_used && key_do_regen) { | |
1252 | generate_ephemeral_server_key(); | |
1253 | key_used = 0; | |
1254 | key_do_regen = 0; | |
1255 | } | |
1256 | if (ret < 0) | |
1257 | continue; | |
1258 | ||
1259 | for (i = 0; i < options.max_startups; i++) | |
1260 | if (startup_pipes[i] != -1 && | |
1261 | FD_ISSET(startup_pipes[i], fdset)) { | |
1262 | /* | |
1263 | * the read end of the pipe is ready | |
1264 | * if the child has closed the pipe | |
1265 | * after successful authentication | |
1266 | * or if the child has died | |
1267 | */ | |
1268 | close(startup_pipes[i]); | |
1269 | startup_pipes[i] = -1; | |
1270 | startups--; | |
1271 | } | |
1272 | for (i = 0; i < num_listen_socks; i++) { | |
1273 | if (!FD_ISSET(listen_socks[i], fdset)) | |
1274 | continue; | |
1275 | fromlen = sizeof(from); | |
1276 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1277 | &fromlen); | |
1278 | if (newsock < 0) { | |
1279 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1280 | error("accept: %.100s", strerror(errno)); | |
1281 | continue; | |
1282 | } | |
3c0ef626 | 1283 | if (drop_connection(startups) == 1) { |
1284 | debug("drop connection #%d", startups); | |
1285 | close(newsock); | |
1286 | continue; | |
1287 | } | |
1288 | if (pipe(startup_p) == -1) { | |
1289 | close(newsock); | |
1290 | continue; | |
1291 | } | |
1292 | ||
1293 | for (j = 0; j < options.max_startups; j++) | |
1294 | if (startup_pipes[j] == -1) { | |
1295 | startup_pipes[j] = startup_p[0]; | |
1296 | if (maxfd < startup_p[0]) | |
1297 | maxfd = startup_p[0]; | |
1298 | startups++; | |
1299 | break; | |
1300 | } | |
1301 | ||
1302 | /* | |
1303 | * Got connection. Fork a child to handle it, unless | |
1304 | * we are in debugging mode. | |
1305 | */ | |
1306 | if (debug_flag) { | |
1307 | /* | |
1308 | * In debugging mode. Close the listening | |
1309 | * socket, and start processing the | |
1310 | * connection without forking. | |
1311 | */ | |
1312 | debug("Server will not fork when running in debugging mode."); | |
1313 | close_listen_socks(); | |
1314 | sock_in = newsock; | |
1315 | sock_out = newsock; | |
1316 | startup_pipe = -1; | |
1317 | pid = getpid(); | |
1318 | break; | |
1319 | } else { | |
1320 | /* | |
1321 | * Normal production daemon. Fork, and have | |
1322 | * the child process the connection. The | |
1323 | * parent continues listening. | |
1324 | */ | |
1325 | if ((pid = fork()) == 0) { | |
1326 | /* | |
1327 | * Child. Close the listening and max_startup | |
1328 | * sockets. Start using the accepted socket. | |
1329 | * Reinitialize logging (since our pid has | |
1330 | * changed). We break out of the loop to handle | |
1331 | * the connection. | |
1332 | */ | |
1333 | startup_pipe = startup_p[1]; | |
e9a17296 | 1334 | close_startup_pipes(); |
3c0ef626 | 1335 | close_listen_socks(); |
1336 | sock_in = newsock; | |
1337 | sock_out = newsock; | |
1338 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1339 | break; | |
1340 | } | |
1341 | } | |
1342 | ||
1343 | /* Parent. Stay in the loop. */ | |
1344 | if (pid < 0) | |
1345 | error("fork: %.100s", strerror(errno)); | |
1346 | else | |
f5799ae1 | 1347 | debug("Forked child %ld.", (long)pid); |
3c0ef626 | 1348 | |
1349 | close(startup_p[1]); | |
1350 | ||
1351 | /* Mark that the key has been used (it was "given" to the child). */ | |
1352 | if ((options.protocol & SSH_PROTO_1) && | |
1353 | key_used == 0) { | |
1354 | /* Schedule server key regeneration alarm. */ | |
1355 | signal(SIGALRM, key_regeneration_alarm); | |
1356 | alarm(options.key_regeneration_time); | |
1357 | key_used = 1; | |
1358 | } | |
1359 | ||
1360 | arc4random_stir(); | |
1361 | ||
1362 | /* Close the new socket (the child is now taking care of it). */ | |
1363 | close(newsock); | |
1364 | } | |
1365 | /* child process check (or debug mode) */ | |
1366 | if (num_listen_socks < 0) | |
1367 | break; | |
1368 | } | |
1369 | } | |
1370 | ||
1371 | /* This is the child processing a new connection. */ | |
1372 | ||
700318f3 | 1373 | /* |
1374 | * Create a new session and process group since the 4.4BSD | |
1375 | * setlogin() affects the entire process group. We don't | |
1376 | * want the child to be able to affect the parent. | |
1377 | */ | |
0fff78ff | 1378 | #if !defined(SSHD_ACQUIRES_CTTY) |
6a9b3198 | 1379 | /* |
0fff78ff | 1380 | * If setsid is called, on some platforms sshd will later acquire a |
1381 | * controlling terminal which will result in "could not set | |
1382 | * controlling tty" errors. | |
6a9b3198 | 1383 | */ |
680cee3b | 1384 | if (!debug_flag && !inetd_flag && setsid() < 0) |
700318f3 | 1385 | error("setsid: %.100s", strerror(errno)); |
7435de97 | 1386 | #endif |
700318f3 | 1387 | |
3c0ef626 | 1388 | /* |
1389 | * Disable the key regeneration alarm. We will not regenerate the | |
1390 | * key since we are no longer in a position to give it to anyone. We | |
1391 | * will not restart on SIGHUP since it no longer makes sense. | |
1392 | */ | |
1393 | alarm(0); | |
1394 | signal(SIGALRM, SIG_DFL); | |
1395 | signal(SIGHUP, SIG_DFL); | |
1396 | signal(SIGTERM, SIG_DFL); | |
1397 | signal(SIGQUIT, SIG_DFL); | |
1398 | signal(SIGCHLD, SIG_DFL); | |
1399 | signal(SIGINT, SIG_DFL); | |
1400 | ||
12408a1b | 1401 | /* Set SO_KEEPALIVE if requested. */ |
1402 | if (options.tcp_keep_alive && | |
e9a17296 | 1403 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, |
3c0ef626 | 1404 | sizeof(on)) < 0) |
1405 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1406 | ||
1407 | /* | |
1408 | * Register our connection. This turns encryption off because we do | |
1409 | * not have a key. | |
1410 | */ | |
1411 | packet_set_connection(sock_in, sock_out); | |
1412 | ||
1413 | remote_port = get_remote_port(); | |
1414 | remote_ip = get_remote_ipaddr(); | |
1415 | ||
1416 | #ifdef LIBWRAP | |
1417 | /* Check whether logins are denied from this host. */ | |
1418 | { | |
1419 | struct request_info req; | |
1420 | ||
1421 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); | |
1422 | fromhost(&req); | |
1423 | ||
1424 | if (!hosts_access(&req)) { | |
1425 | debug("Connection refused by tcp wrapper"); | |
1426 | refuse(&req); | |
1427 | /* NOTREACHED */ | |
1428 | fatal("libwrap refuse returns"); | |
1429 | } | |
1430 | } | |
1431 | #endif /* LIBWRAP */ | |
1432 | ||
1433 | /* Log the connection. */ | |
1434 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
1435 | ||
1436 | /* | |
1437 | * We don\'t want to listen forever unless the other side | |
1438 | * successfully authenticates itself. So we set up an alarm which is | |
1439 | * cleared after successful authentication. A limit of zero | |
1440 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1441 | * mode; it is just annoying to have the server exit just when you | |
1442 | * are about to discover the bug. | |
1443 | */ | |
1444 | signal(SIGALRM, grace_alarm_handler); | |
1445 | if (!debug_flag) | |
1446 | alarm(options.login_grace_time); | |
1447 | ||
1448 | sshd_exchange_identification(sock_in, sock_out); | |
3c0ef626 | 1449 | |
1450 | packet_set_nonblocking(); | |
1451 | ||
12408a1b | 1452 | /* prepare buffers to collect authentication messages */ |
0fff78ff | 1453 | buffer_init(&loginmsg); |
1454 | ||
12408a1b | 1455 | /* allocate authentication context */ |
1456 | authctxt = xmalloc(sizeof(*authctxt)); | |
1457 | memset(authctxt, 0, sizeof(*authctxt)); | |
1458 | ||
1459 | /* XXX global for cleanup, access from other modules */ | |
1460 | the_authctxt = authctxt; | |
1461 | ||
700318f3 | 1462 | if (use_privsep) |
12408a1b | 1463 | if (privsep_preauth(authctxt) == 1) |
700318f3 | 1464 | goto authenticated; |
1465 | ||
3c0ef626 | 1466 | /* perform the key exchange */ |
1467 | /* authenticate user and start session */ | |
1468 | if (compat20) { | |
1469 | do_ssh2_kex(); | |
12408a1b | 1470 | do_authentication2(authctxt); |
3c0ef626 | 1471 | } else { |
1472 | do_ssh1_kex(); | |
12408a1b | 1473 | do_authentication(authctxt); |
700318f3 | 1474 | } |
1475 | /* | |
1476 | * If we use privilege separation, the unprivileged child transfers | |
1477 | * the current keystate and exits | |
1478 | */ | |
1479 | if (use_privsep) { | |
1480 | mm_send_keystate(pmonitor); | |
1481 | exit(0); | |
1482 | } | |
1483 | ||
1484 | authenticated: | |
1485 | /* | |
1486 | * In privilege separation, we fork another child and prepare | |
1487 | * file descriptor passing. | |
1488 | */ | |
1489 | if (use_privsep) { | |
1490 | privsep_postauth(authctxt); | |
1491 | /* the monitor process [priv] will not return */ | |
1492 | if (!compat20) | |
1493 | destroy_sensitive_data(); | |
3c0ef626 | 1494 | } |
700318f3 | 1495 | |
12408a1b | 1496 | /* Start session. */ |
700318f3 | 1497 | do_authenticated(authctxt); |
1498 | ||
3c0ef626 | 1499 | /* The connection has been terminated. */ |
1500 | verbose("Closing connection to %.100s", remote_ip); | |
1501 | ||
1502 | #ifdef USE_PAM | |
0fff78ff | 1503 | if (options.use_pam) |
1504 | finish_pam(); | |
3c0ef626 | 1505 | #endif /* USE_PAM */ |
1506 | ||
1507 | packet_close(); | |
700318f3 | 1508 | |
1509 | if (use_privsep) | |
1510 | mm_terminate(); | |
1511 | ||
3c0ef626 | 1512 | exit(0); |
1513 | } | |
1514 | ||
700318f3 | 1515 | /* |
1516 | * Decrypt session_key_int using our private server key and private host key | |
1517 | * (key with larger modulus first). | |
1518 | */ | |
1519 | int | |
1520 | ssh1_session_key(BIGNUM *session_key_int) | |
1521 | { | |
1522 | int rsafail = 0; | |
1523 | ||
1524 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1525 | /* Server key has bigger modulus. */ | |
1526 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1527 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1528 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1529 | get_remote_ipaddr(), | |
1530 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1531 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1532 | SSH_KEY_BITS_RESERVED); | |
1533 | } | |
1534 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1535 | sensitive_data.server_key->rsa) <= 0) | |
1536 | rsafail++; | |
1537 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1538 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1539 | rsafail++; | |
1540 | } else { | |
1541 | /* Host key has bigger modulus (or they are equal). */ | |
1542 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1543 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1544 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1545 | get_remote_ipaddr(), | |
1546 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1547 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1548 | SSH_KEY_BITS_RESERVED); | |
1549 | } | |
1550 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1551 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1552 | rsafail++; | |
1553 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1554 | sensitive_data.server_key->rsa) < 0) | |
1555 | rsafail++; | |
1556 | } | |
1557 | return (rsafail); | |
1558 | } | |
3c0ef626 | 1559 | /* |
1560 | * SSH1 key exchange | |
1561 | */ | |
1562 | static void | |
1563 | do_ssh1_kex(void) | |
1564 | { | |
1565 | int i, len; | |
3c0ef626 | 1566 | int rsafail = 0; |
1567 | BIGNUM *session_key_int; | |
1568 | u_char session_key[SSH_SESSION_KEY_LENGTH]; | |
1569 | u_char cookie[8]; | |
1570 | u_int cipher_type, auth_mask, protocol_flags; | |
41b2f314 | 1571 | u_int32_t rnd = 0; |
3c0ef626 | 1572 | |
1573 | /* | |
1574 | * Generate check bytes that the client must send back in the user | |
1575 | * packet in order for it to be accepted; this is used to defy ip | |
1576 | * spoofing attacks. Note that this only works against somebody | |
1577 | * doing IP spoofing from a remote machine; any machine on the local | |
1578 | * network can still see outgoing packets and catch the random | |
1579 | * cookie. This only affects rhosts authentication, and this is one | |
1580 | * of the reasons why it is inherently insecure. | |
1581 | */ | |
1582 | for (i = 0; i < 8; i++) { | |
1583 | if (i % 4 == 0) | |
41b2f314 | 1584 | rnd = arc4random(); |
1585 | cookie[i] = rnd & 0xff; | |
1586 | rnd >>= 8; | |
3c0ef626 | 1587 | } |
1588 | ||
1589 | /* | |
1590 | * Send our public key. We include in the packet 64 bits of random | |
1591 | * data that must be matched in the reply in order to prevent IP | |
1592 | * spoofing. | |
1593 | */ | |
1594 | packet_start(SSH_SMSG_PUBLIC_KEY); | |
1595 | for (i = 0; i < 8; i++) | |
1596 | packet_put_char(cookie[i]); | |
1597 | ||
1598 | /* Store our public server RSA key. */ | |
1599 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); | |
1600 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1601 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
1602 | ||
1603 | /* Store our public host RSA key. */ | |
1604 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1605 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1606 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
1607 | ||
1608 | /* Put protocol flags. */ | |
1609 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1610 | ||
1611 | /* Declare which ciphers we support. */ | |
1612 | packet_put_int(cipher_mask_ssh1(0)); | |
1613 | ||
1614 | /* Declare supported authentication types. */ | |
1615 | auth_mask = 0; | |
3c0ef626 | 1616 | if (options.rhosts_rsa_authentication) |
1617 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1618 | if (options.rsa_authentication) | |
1619 | auth_mask |= 1 << SSH_AUTH_RSA; | |
3c0ef626 | 1620 | if (options.challenge_response_authentication == 1) |
1621 | auth_mask |= 1 << SSH_AUTH_TIS; | |
1622 | if (options.password_authentication) | |
1623 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1624 | packet_put_int(auth_mask); | |
1625 | ||
1626 | /* Send the packet and wait for it to be sent. */ | |
1627 | packet_send(); | |
1628 | packet_write_wait(); | |
1629 | ||
1630 | debug("Sent %d bit server key and %d bit host key.", | |
1631 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1632 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1633 | ||
1634 | /* Read clients reply (cipher type and session key). */ | |
e9a17296 | 1635 | packet_read_expect(SSH_CMSG_SESSION_KEY); |
3c0ef626 | 1636 | |
1637 | /* Get cipher type and check whether we accept this. */ | |
1638 | cipher_type = packet_get_char(); | |
1639 | ||
1640 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) | |
1641 | packet_disconnect("Warning: client selects unsupported cipher."); | |
1642 | ||
1643 | /* Get check bytes from the packet. These must match those we | |
1644 | sent earlier with the public key packet. */ | |
1645 | for (i = 0; i < 8; i++) | |
1646 | if (cookie[i] != packet_get_char()) | |
1647 | packet_disconnect("IP Spoofing check bytes do not match."); | |
1648 | ||
1649 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1650 | ||
1651 | /* Get the encrypted integer. */ | |
e9a17296 | 1652 | if ((session_key_int = BN_new()) == NULL) |
1653 | fatal("do_ssh1_kex: BN_new failed"); | |
1654 | packet_get_bignum(session_key_int); | |
3c0ef626 | 1655 | |
1656 | protocol_flags = packet_get_int(); | |
1657 | packet_set_protocol_flags(protocol_flags); | |
e9a17296 | 1658 | packet_check_eom(); |
3c0ef626 | 1659 | |
700318f3 | 1660 | /* Decrypt session_key_int using host/server keys */ |
1661 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); | |
1662 | ||
3c0ef626 | 1663 | /* |
1664 | * Extract session key from the decrypted integer. The key is in the | |
1665 | * least significant 256 bits of the integer; the first byte of the | |
1666 | * key is in the highest bits. | |
1667 | */ | |
1668 | if (!rsafail) { | |
1669 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1670 | len = BN_num_bytes(session_key_int); | |
1671 | if (len < 0 || len > sizeof(session_key)) { | |
1672 | error("do_connection: bad session key len from %s: " | |
1673 | "session_key_int %d > sizeof(session_key) %lu", | |
1674 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
1675 | rsafail++; | |
1676 | } else { | |
1677 | memset(session_key, 0, sizeof(session_key)); | |
1678 | BN_bn2bin(session_key_int, | |
1679 | session_key + sizeof(session_key) - len); | |
1680 | ||
1681 | compute_session_id(session_id, cookie, | |
1682 | sensitive_data.ssh1_host_key->rsa->n, | |
1683 | sensitive_data.server_key->rsa->n); | |
1684 | /* | |
1685 | * Xor the first 16 bytes of the session key with the | |
1686 | * session id. | |
1687 | */ | |
1688 | for (i = 0; i < 16; i++) | |
1689 | session_key[i] ^= session_id[i]; | |
1690 | } | |
1691 | } | |
1692 | if (rsafail) { | |
1693 | int bytes = BN_num_bytes(session_key_int); | |
e9a17296 | 1694 | u_char *buf = xmalloc(bytes); |
3c0ef626 | 1695 | MD5_CTX md; |
1696 | ||
0fff78ff | 1697 | logit("do_connection: generating a fake encryption key"); |
3c0ef626 | 1698 | BN_bn2bin(session_key_int, buf); |
1699 | MD5_Init(&md); | |
1700 | MD5_Update(&md, buf, bytes); | |
1701 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1702 | MD5_Final(session_key, &md); | |
1703 | MD5_Init(&md); | |
1704 | MD5_Update(&md, session_key, 16); | |
1705 | MD5_Update(&md, buf, bytes); | |
1706 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1707 | MD5_Final(session_key + 16, &md); | |
1708 | memset(buf, 0, bytes); | |
1709 | xfree(buf); | |
1710 | for (i = 0; i < 16; i++) | |
1711 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
1712 | } | |
700318f3 | 1713 | /* Destroy the private and public keys. No longer. */ |
3c0ef626 | 1714 | destroy_sensitive_data(); |
1715 | ||
700318f3 | 1716 | if (use_privsep) |
1717 | mm_ssh1_session_id(session_id); | |
1718 | ||
3c0ef626 | 1719 | /* Destroy the decrypted integer. It is no longer needed. */ |
1720 | BN_clear_free(session_key_int); | |
1721 | ||
1722 | /* Set the session key. From this on all communications will be encrypted. */ | |
1723 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1724 | ||
1725 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1726 | memset(session_key, 0, sizeof(session_key)); | |
1727 | ||
1728 | debug("Received session key; encryption turned on."); | |
1729 | ||
f5799ae1 | 1730 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ |
3c0ef626 | 1731 | packet_start(SSH_SMSG_SUCCESS); |
1732 | packet_send(); | |
1733 | packet_write_wait(); | |
1734 | } | |
1735 | ||
1736 | /* | |
1737 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1738 | */ | |
1739 | static void | |
1740 | do_ssh2_kex(void) | |
1741 | { | |
1742 | Kex *kex; | |
1743 | ||
1744 | if (options.ciphers != NULL) { | |
1745 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
1746 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
1747 | } | |
1748 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
1749 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
1750 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
1751 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
1752 | ||
1753 | if (options.macs != NULL) { | |
1754 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1755 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1756 | } | |
f5799ae1 | 1757 | if (!options.compression) { |
1758 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
1759 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1760 | } | |
3c0ef626 | 1761 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1762 | ||
1763 | /* start key exchange */ | |
1764 | kex = kex_setup(myproposal); | |
6a9b3198 | 1765 | kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; |
1766 | kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; | |
3c0ef626 | 1767 | kex->server = 1; |
1768 | kex->client_version_string=client_version_string; | |
1769 | kex->server_version_string=server_version_string; | |
1770 | kex->load_host_key=&get_hostkey_by_type; | |
700318f3 | 1771 | kex->host_key_index=&get_hostkey_index; |
3c0ef626 | 1772 | |
1773 | xxx_kex = kex; | |
1774 | ||
1775 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); | |
1776 | ||
1777 | session_id2 = kex->session_id; | |
1778 | session_id2_len = kex->session_id_len; | |
1779 | ||
1780 | #ifdef DEBUG_KEXDH | |
1781 | /* send 1st encrypted/maced/compressed message */ | |
1782 | packet_start(SSH2_MSG_IGNORE); | |
1783 | packet_put_cstring("markus"); | |
1784 | packet_send(); | |
1785 | packet_write_wait(); | |
1786 | #endif | |
1787 | debug("KEX done"); | |
1788 | } | |
12408a1b | 1789 | |
1790 | /* server specific fatal cleanup */ | |
1791 | void | |
1792 | cleanup_exit(int i) | |
1793 | { | |
1794 | if (the_authctxt) | |
1795 | do_cleanup(the_authctxt); | |
1796 | _exit(i); | |
1797 | } |