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2e437378 | 1 | /* $OpenBSD: packet.c,v 1.145 2006/09/19 21:14:08 markus Exp $ */ |
3c0ef626 | 2 | /* |
3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | * All rights reserved | |
6 | * This file contains code implementing the packet protocol and communication | |
7 | * with the other side. This same code is used both on client and server side. | |
8 | * | |
9 | * As far as I am concerned, the code I have written for this software | |
10 | * can be used freely for any purpose. Any derived versions of this | |
11 | * software must be clearly marked as such, and if the derived work is | |
12 | * incompatible with the protocol description in the RFC file, it must be | |
13 | * called by a name other than "ssh" or "Secure Shell". | |
14 | * | |
15 | * | |
16 | * SSH2 packet format added by Markus Friedl. | |
17 | * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. | |
18 | * | |
19 | * Redistribution and use in source and binary forms, with or without | |
20 | * modification, are permitted provided that the following conditions | |
21 | * are met: | |
22 | * 1. Redistributions of source code must retain the above copyright | |
23 | * notice, this list of conditions and the following disclaimer. | |
24 | * 2. Redistributions in binary form must reproduce the above copyright | |
25 | * notice, this list of conditions and the following disclaimer in the | |
26 | * documentation and/or other materials provided with the distribution. | |
27 | * | |
28 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
29 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
30 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
31 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
33 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
34 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
35 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
36 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
37 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
38 | */ | |
39 | ||
40 | #include "includes.h" | |
2e437378 | 41 | |
42 | #include <sys/types.h> | |
70791e56 | 43 | #include "openbsd-compat/sys-queue.h" |
2e437378 | 44 | #include <sys/param.h> |
45 | #include <sys/socket.h> | |
46 | #ifdef HAVE_SYS_TIME_H | |
47 | # include <sys/time.h> | |
48 | #endif | |
49 | ||
50 | #include <netinet/in_systm.h> | |
51 | #include <netinet/in.h> | |
52 | #include <netinet/ip.h> | |
53 | #include <arpa/inet.h> | |
54 | ||
55 | #include <errno.h> | |
56 | #include <stdarg.h> | |
57 | #include <stdio.h> | |
58 | #include <stdlib.h> | |
59 | #include <string.h> | |
60 | #include <unistd.h> | |
61 | #include <signal.h> | |
3c0ef626 | 62 | |
63 | #include "xmalloc.h" | |
64 | #include "buffer.h" | |
65 | #include "packet.h" | |
3c0ef626 | 66 | #include "crc32.h" |
3c0ef626 | 67 | #include "compress.h" |
68 | #include "deattack.h" | |
69 | #include "channels.h" | |
3c0ef626 | 70 | #include "compat.h" |
71 | #include "ssh1.h" | |
72 | #include "ssh2.h" | |
3c0ef626 | 73 | #include "cipher.h" |
2e437378 | 74 | #include "key.h" |
3c0ef626 | 75 | #include "kex.h" |
76 | #include "mac.h" | |
77 | #include "log.h" | |
78 | #include "canohost.h" | |
1e608e42 | 79 | #include "misc.h" |
ff2d7a98 | 80 | #include "ssh.h" |
3c0ef626 | 81 | |
82 | #ifdef PACKET_DEBUG | |
83 | #define DBG(x) x | |
84 | #else | |
85 | #define DBG(x) | |
86 | #endif | |
87 | ||
88 | /* | |
89 | * This variable contains the file descriptors used for communicating with | |
90 | * the other side. connection_in is used for reading; connection_out for | |
91 | * writing. These can be the same descriptor, in which case it is assumed to | |
92 | * be a socket. | |
93 | */ | |
94 | static int connection_in = -1; | |
95 | static int connection_out = -1; | |
96 | ||
97 | /* Protocol flags for the remote side. */ | |
98 | static u_int remote_protocol_flags = 0; | |
99 | ||
100 | /* Encryption context for receiving data. This is only used for decryption. */ | |
101 | static CipherContext receive_context; | |
102 | ||
103 | /* Encryption context for sending data. This is only used for encryption. */ | |
104 | static CipherContext send_context; | |
105 | ||
106 | /* Buffer for raw input data from the socket. */ | |
2980ea68 | 107 | Buffer input; |
3c0ef626 | 108 | |
109 | /* Buffer for raw output data going to the socket. */ | |
2980ea68 | 110 | Buffer output; |
3c0ef626 | 111 | |
112 | /* Buffer for the partial outgoing packet being constructed. */ | |
113 | static Buffer outgoing_packet; | |
114 | ||
115 | /* Buffer for the incoming packet currently being processed. */ | |
116 | static Buffer incoming_packet; | |
117 | ||
118 | /* Scratch buffer for packet compression/decompression. */ | |
119 | static Buffer compression_buffer; | |
120 | static int compression_buffer_ready = 0; | |
121 | ||
122 | /* Flag indicating whether packet compression/decompression is enabled. */ | |
123 | static int packet_compression = 0; | |
124 | ||
125 | /* default maximum packet size */ | |
70791e56 | 126 | u_int max_packet_size = 32768; |
3c0ef626 | 127 | |
128 | /* Flag indicating whether this module has been initialized. */ | |
129 | static int initialized = 0; | |
130 | ||
131 | /* Set to true if the connection is interactive. */ | |
132 | static int interactive_mode = 0; | |
133 | ||
34fee935 | 134 | /* Set to true if we are the server side. */ |
135 | static int server_side = 0; | |
136 | ||
137 | /* Set to true if we are authenticated. */ | |
138 | static int after_authentication = 0; | |
139 | ||
3c0ef626 | 140 | /* Session key information for Encryption and MAC */ |
141 | Newkeys *newkeys[MODE_MAX]; | |
70791e56 | 142 | static struct packet_state { |
143 | u_int32_t seqnr; | |
144 | u_int32_t packets; | |
145 | u_int64_t blocks; | |
146 | } p_read, p_send; | |
147 | ||
148 | static u_int64_t max_blocks_in, max_blocks_out; | |
149 | static u_int32_t rekey_limit; | |
3c0ef626 | 150 | |
ff2d7a98 | 151 | /* Session key for protocol v1 */ |
152 | static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; | |
153 | static u_int ssh1_keylen; | |
154 | ||
3c0ef626 | 155 | /* roundup current message to extra_pad bytes */ |
156 | static u_char extra_pad = 0; | |
157 | ||
70791e56 | 158 | struct packet { |
159 | TAILQ_ENTRY(packet) next; | |
160 | u_char type; | |
161 | Buffer payload; | |
162 | }; | |
163 | TAILQ_HEAD(, packet) outgoing; | |
164 | ||
3c0ef626 | 165 | /* |
166 | * Sets the descriptors used for communication. Disables encryption until | |
167 | * packet_set_encryption_key is called. | |
168 | */ | |
169 | void | |
170 | packet_set_connection(int fd_in, int fd_out) | |
171 | { | |
172 | Cipher *none = cipher_by_name("none"); | |
e54b3d7c | 173 | |
3c0ef626 | 174 | if (none == NULL) |
175 | fatal("packet_set_connection: cannot load cipher 'none'"); | |
176 | connection_in = fd_in; | |
177 | connection_out = fd_out; | |
1b56ff3d | 178 | cipher_init(&send_context, none, (const u_char *)"", |
179 | 0, NULL, 0, CIPHER_ENCRYPT); | |
180 | cipher_init(&receive_context, none, (const u_char *)"", | |
181 | 0, NULL, 0, CIPHER_DECRYPT); | |
3c0ef626 | 182 | newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; |
183 | if (!initialized) { | |
184 | initialized = 1; | |
185 | buffer_init(&input); | |
186 | buffer_init(&output); | |
187 | buffer_init(&outgoing_packet); | |
188 | buffer_init(&incoming_packet); | |
70791e56 | 189 | TAILQ_INIT(&outgoing); |
3c0ef626 | 190 | } |
3c0ef626 | 191 | } |
192 | ||
193 | /* Returns 1 if remote host is connected via socket, 0 if not. */ | |
194 | ||
195 | int | |
1e608e42 | 196 | packet_connection_is_on_socket(void) |
3c0ef626 | 197 | { |
198 | struct sockaddr_storage from, to; | |
199 | socklen_t fromlen, tolen; | |
200 | ||
201 | /* filedescriptors in and out are the same, so it's a socket */ | |
202 | if (connection_in == connection_out) | |
203 | return 1; | |
204 | fromlen = sizeof(from); | |
205 | memset(&from, 0, sizeof(from)); | |
206 | if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) | |
207 | return 0; | |
208 | tolen = sizeof(to); | |
209 | memset(&to, 0, sizeof(to)); | |
210 | if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
211 | return 0; | |
212 | if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) | |
213 | return 0; | |
214 | if (from.ss_family != AF_INET && from.ss_family != AF_INET6) | |
215 | return 0; | |
216 | return 1; | |
217 | } | |
218 | ||
2980ea68 | 219 | /* |
220 | * Exports an IV from the CipherContext required to export the key | |
221 | * state back from the unprivileged child to the privileged parent | |
222 | * process. | |
223 | */ | |
224 | ||
225 | void | |
226 | packet_get_keyiv(int mode, u_char *iv, u_int len) | |
227 | { | |
228 | CipherContext *cc; | |
229 | ||
230 | if (mode == MODE_OUT) | |
231 | cc = &send_context; | |
232 | else | |
233 | cc = &receive_context; | |
234 | ||
235 | cipher_get_keyiv(cc, iv, len); | |
236 | } | |
237 | ||
238 | int | |
239 | packet_get_keycontext(int mode, u_char *dat) | |
240 | { | |
241 | CipherContext *cc; | |
242 | ||
243 | if (mode == MODE_OUT) | |
244 | cc = &send_context; | |
245 | else | |
246 | cc = &receive_context; | |
247 | ||
248 | return (cipher_get_keycontext(cc, dat)); | |
249 | } | |
250 | ||
251 | void | |
252 | packet_set_keycontext(int mode, u_char *dat) | |
253 | { | |
254 | CipherContext *cc; | |
255 | ||
256 | if (mode == MODE_OUT) | |
257 | cc = &send_context; | |
258 | else | |
259 | cc = &receive_context; | |
260 | ||
261 | cipher_set_keycontext(cc, dat); | |
262 | } | |
263 | ||
264 | int | |
265 | packet_get_keyiv_len(int mode) | |
266 | { | |
267 | CipherContext *cc; | |
268 | ||
269 | if (mode == MODE_OUT) | |
270 | cc = &send_context; | |
271 | else | |
272 | cc = &receive_context; | |
273 | ||
274 | return (cipher_get_keyiv_len(cc)); | |
275 | } | |
2e437378 | 276 | |
2980ea68 | 277 | void |
278 | packet_set_iv(int mode, u_char *dat) | |
279 | { | |
280 | CipherContext *cc; | |
281 | ||
282 | if (mode == MODE_OUT) | |
283 | cc = &send_context; | |
284 | else | |
285 | cc = &receive_context; | |
286 | ||
287 | cipher_set_keyiv(cc, dat); | |
288 | } | |
2e437378 | 289 | |
2980ea68 | 290 | int |
70791e56 | 291 | packet_get_ssh1_cipher(void) |
2980ea68 | 292 | { |
293 | return (cipher_get_number(receive_context.cipher)); | |
294 | } | |
295 | ||
70791e56 | 296 | void |
297 | packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets) | |
2980ea68 | 298 | { |
70791e56 | 299 | struct packet_state *state; |
300 | ||
301 | state = (mode == MODE_IN) ? &p_read : &p_send; | |
302 | *seqnr = state->seqnr; | |
303 | *blocks = state->blocks; | |
304 | *packets = state->packets; | |
2980ea68 | 305 | } |
306 | ||
307 | void | |
70791e56 | 308 | packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets) |
2980ea68 | 309 | { |
70791e56 | 310 | struct packet_state *state; |
311 | ||
312 | state = (mode == MODE_IN) ? &p_read : &p_send; | |
313 | state->seqnr = seqnr; | |
314 | state->blocks = blocks; | |
315 | state->packets = packets; | |
2980ea68 | 316 | } |
317 | ||
3c0ef626 | 318 | /* returns 1 if connection is via ipv4 */ |
319 | ||
320 | int | |
1e608e42 | 321 | packet_connection_is_ipv4(void) |
3c0ef626 | 322 | { |
323 | struct sockaddr_storage to; | |
324 | socklen_t tolen = sizeof(to); | |
325 | ||
326 | memset(&to, 0, sizeof(to)); | |
327 | if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
328 | return 0; | |
2980ea68 | 329 | if (to.ss_family == AF_INET) |
330 | return 1; | |
331 | #ifdef IPV4_IN_IPV6 | |
416fd2a8 | 332 | if (to.ss_family == AF_INET6 && |
2980ea68 | 333 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) |
334 | return 1; | |
335 | #endif | |
336 | return 0; | |
3c0ef626 | 337 | } |
338 | ||
339 | /* Sets the connection into non-blocking mode. */ | |
340 | ||
341 | void | |
1e608e42 | 342 | packet_set_nonblocking(void) |
3c0ef626 | 343 | { |
344 | /* Set the socket into non-blocking mode. */ | |
1b56ff3d | 345 | set_nonblock(connection_in); |
3c0ef626 | 346 | |
1b56ff3d | 347 | if (connection_out != connection_in) |
348 | set_nonblock(connection_out); | |
3c0ef626 | 349 | } |
350 | ||
351 | /* Returns the socket used for reading. */ | |
352 | ||
353 | int | |
1e608e42 | 354 | packet_get_connection_in(void) |
3c0ef626 | 355 | { |
356 | return connection_in; | |
357 | } | |
358 | ||
359 | /* Returns the descriptor used for writing. */ | |
360 | ||
361 | int | |
1e608e42 | 362 | packet_get_connection_out(void) |
3c0ef626 | 363 | { |
364 | return connection_out; | |
365 | } | |
366 | ||
367 | /* Closes the connection and clears and frees internal data structures. */ | |
368 | ||
369 | void | |
1e608e42 | 370 | packet_close(void) |
3c0ef626 | 371 | { |
372 | if (!initialized) | |
373 | return; | |
374 | initialized = 0; | |
375 | if (connection_in == connection_out) { | |
376 | shutdown(connection_out, SHUT_RDWR); | |
377 | close(connection_out); | |
378 | } else { | |
379 | close(connection_in); | |
380 | close(connection_out); | |
381 | } | |
382 | buffer_free(&input); | |
383 | buffer_free(&output); | |
384 | buffer_free(&outgoing_packet); | |
385 | buffer_free(&incoming_packet); | |
386 | if (compression_buffer_ready) { | |
387 | buffer_free(&compression_buffer); | |
388 | buffer_compress_uninit(); | |
389 | } | |
1e608e42 | 390 | cipher_cleanup(&send_context); |
391 | cipher_cleanup(&receive_context); | |
3c0ef626 | 392 | } |
393 | ||
394 | /* Sets remote side protocol flags. */ | |
395 | ||
396 | void | |
397 | packet_set_protocol_flags(u_int protocol_flags) | |
398 | { | |
399 | remote_protocol_flags = protocol_flags; | |
400 | } | |
401 | ||
402 | /* Returns the remote protocol flags set earlier by the above function. */ | |
403 | ||
404 | u_int | |
1e608e42 | 405 | packet_get_protocol_flags(void) |
3c0ef626 | 406 | { |
407 | return remote_protocol_flags; | |
408 | } | |
409 | ||
410 | /* | |
411 | * Starts packet compression from the next packet on in both directions. | |
412 | * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. | |
413 | */ | |
414 | ||
415 | static void | |
416 | packet_init_compression(void) | |
417 | { | |
418 | if (compression_buffer_ready == 1) | |
419 | return; | |
420 | compression_buffer_ready = 1; | |
421 | buffer_init(&compression_buffer); | |
422 | } | |
423 | ||
424 | void | |
425 | packet_start_compression(int level) | |
426 | { | |
427 | if (packet_compression && !compat20) | |
428 | fatal("Compression already enabled."); | |
429 | packet_compression = 1; | |
430 | packet_init_compression(); | |
431 | buffer_compress_init_send(level); | |
432 | buffer_compress_init_recv(); | |
433 | } | |
434 | ||
435 | /* | |
436 | * Causes any further packets to be encrypted using the given key. The same | |
437 | * key is used for both sending and reception. However, both directions are | |
438 | * encrypted independently of each other. | |
439 | */ | |
ff2d7a98 | 440 | |
3c0ef626 | 441 | void |
442 | packet_set_encryption_key(const u_char *key, u_int keylen, | |
443 | int number) | |
444 | { | |
445 | Cipher *cipher = cipher_by_number(number); | |
e54b3d7c | 446 | |
3c0ef626 | 447 | if (cipher == NULL) |
448 | fatal("packet_set_encryption_key: unknown cipher number %d", number); | |
449 | if (keylen < 20) | |
450 | fatal("packet_set_encryption_key: keylen too small: %d", keylen); | |
ff2d7a98 | 451 | if (keylen > SSH_SESSION_KEY_LENGTH) |
452 | fatal("packet_set_encryption_key: keylen too big: %d", keylen); | |
453 | memcpy(ssh1_key, key, keylen); | |
454 | ssh1_keylen = keylen; | |
1e608e42 | 455 | cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); |
456 | cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); | |
3c0ef626 | 457 | } |
458 | ||
ff2d7a98 | 459 | u_int |
460 | packet_get_encryption_key(u_char *key) | |
461 | { | |
462 | if (key == NULL) | |
463 | return (ssh1_keylen); | |
464 | memcpy(key, ssh1_key, ssh1_keylen); | |
465 | return (ssh1_keylen); | |
466 | } | |
467 | ||
3c0ef626 | 468 | /* Start constructing a packet to send. */ |
469 | void | |
470 | packet_start(u_char type) | |
471 | { | |
472 | u_char buf[9]; | |
473 | int len; | |
474 | ||
475 | DBG(debug("packet_start[%d]", type)); | |
476 | len = compat20 ? 6 : 9; | |
477 | memset(buf, 0, len - 1); | |
478 | buf[len - 1] = type; | |
479 | buffer_clear(&outgoing_packet); | |
480 | buffer_append(&outgoing_packet, buf, len); | |
481 | } | |
482 | ||
483 | /* Append payload. */ | |
484 | void | |
485 | packet_put_char(int value) | |
486 | { | |
487 | char ch = value; | |
e54b3d7c | 488 | |
3c0ef626 | 489 | buffer_append(&outgoing_packet, &ch, 1); |
490 | } | |
2e437378 | 491 | |
3c0ef626 | 492 | void |
493 | packet_put_int(u_int value) | |
494 | { | |
495 | buffer_put_int(&outgoing_packet, value); | |
496 | } | |
2e437378 | 497 | |
3c0ef626 | 498 | void |
1e608e42 | 499 | packet_put_string(const void *buf, u_int len) |
3c0ef626 | 500 | { |
501 | buffer_put_string(&outgoing_packet, buf, len); | |
502 | } | |
2e437378 | 503 | |
3c0ef626 | 504 | void |
505 | packet_put_cstring(const char *str) | |
506 | { | |
507 | buffer_put_cstring(&outgoing_packet, str); | |
508 | } | |
2e437378 | 509 | |
3c0ef626 | 510 | void |
1e608e42 | 511 | packet_put_raw(const void *buf, u_int len) |
3c0ef626 | 512 | { |
513 | buffer_append(&outgoing_packet, buf, len); | |
514 | } | |
2e437378 | 515 | |
3c0ef626 | 516 | void |
517 | packet_put_bignum(BIGNUM * value) | |
518 | { | |
519 | buffer_put_bignum(&outgoing_packet, value); | |
520 | } | |
2e437378 | 521 | |
3c0ef626 | 522 | void |
523 | packet_put_bignum2(BIGNUM * value) | |
524 | { | |
525 | buffer_put_bignum2(&outgoing_packet, value); | |
526 | } | |
527 | ||
528 | /* | |
529 | * Finalizes and sends the packet. If the encryption key has been set, | |
530 | * encrypts the packet before sending. | |
531 | */ | |
532 | ||
533 | static void | |
534 | packet_send1(void) | |
535 | { | |
1e608e42 | 536 | u_char buf[8], *cp; |
3c0ef626 | 537 | int i, padding, len; |
538 | u_int checksum; | |
1b56ff3d | 539 | u_int32_t rnd = 0; |
3c0ef626 | 540 | |
541 | /* | |
542 | * If using packet compression, compress the payload of the outgoing | |
543 | * packet. | |
544 | */ | |
545 | if (packet_compression) { | |
546 | buffer_clear(&compression_buffer); | |
547 | /* Skip padding. */ | |
548 | buffer_consume(&outgoing_packet, 8); | |
549 | /* padding */ | |
550 | buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); | |
551 | buffer_compress(&outgoing_packet, &compression_buffer); | |
552 | buffer_clear(&outgoing_packet); | |
553 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
1e608e42 | 554 | buffer_len(&compression_buffer)); |
3c0ef626 | 555 | } |
556 | /* Compute packet length without padding (add checksum, remove padding). */ | |
557 | len = buffer_len(&outgoing_packet) + 4 - 8; | |
558 | ||
559 | /* Insert padding. Initialized to zero in packet_start1() */ | |
560 | padding = 8 - len % 8; | |
1e608e42 | 561 | if (!send_context.plaintext) { |
3c0ef626 | 562 | cp = buffer_ptr(&outgoing_packet); |
563 | for (i = 0; i < padding; i++) { | |
564 | if (i % 4 == 0) | |
1b56ff3d | 565 | rnd = arc4random(); |
566 | cp[7 - i] = rnd & 0xff; | |
567 | rnd >>= 8; | |
3c0ef626 | 568 | } |
569 | } | |
570 | buffer_consume(&outgoing_packet, 8 - padding); | |
571 | ||
572 | /* Add check bytes. */ | |
1e608e42 | 573 | checksum = ssh_crc32(buffer_ptr(&outgoing_packet), |
3c0ef626 | 574 | buffer_len(&outgoing_packet)); |
2e437378 | 575 | put_u32(buf, checksum); |
3c0ef626 | 576 | buffer_append(&outgoing_packet, buf, 4); |
577 | ||
578 | #ifdef PACKET_DEBUG | |
579 | fprintf(stderr, "packet_send plain: "); | |
580 | buffer_dump(&outgoing_packet); | |
581 | #endif | |
582 | ||
583 | /* Append to output. */ | |
2e437378 | 584 | put_u32(buf, len); |
3c0ef626 | 585 | buffer_append(&output, buf, 4); |
1e608e42 | 586 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); |
587 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
588 | buffer_len(&outgoing_packet)); | |
3c0ef626 | 589 | |
590 | #ifdef PACKET_DEBUG | |
591 | fprintf(stderr, "encrypted: "); | |
592 | buffer_dump(&output); | |
593 | #endif | |
594 | ||
595 | buffer_clear(&outgoing_packet); | |
596 | ||
597 | /* | |
e00da40d | 598 | * Note that the packet is now only buffered in output. It won't be |
3c0ef626 | 599 | * actually sent until packet_write_wait or packet_write_poll is |
600 | * called. | |
601 | */ | |
602 | } | |
603 | ||
2980ea68 | 604 | void |
3c0ef626 | 605 | set_newkeys(int mode) |
606 | { | |
607 | Enc *enc; | |
608 | Mac *mac; | |
609 | Comp *comp; | |
610 | CipherContext *cc; | |
70791e56 | 611 | u_int64_t *max_blocks; |
1b56ff3d | 612 | int crypt_type; |
3c0ef626 | 613 | |
1c14df9e | 614 | debug2("set_newkeys: mode %d", mode); |
3c0ef626 | 615 | |
1e608e42 | 616 | if (mode == MODE_OUT) { |
617 | cc = &send_context; | |
1b56ff3d | 618 | crypt_type = CIPHER_ENCRYPT; |
70791e56 | 619 | p_send.packets = p_send.blocks = 0; |
620 | max_blocks = &max_blocks_out; | |
1e608e42 | 621 | } else { |
622 | cc = &receive_context; | |
1b56ff3d | 623 | crypt_type = CIPHER_DECRYPT; |
70791e56 | 624 | p_read.packets = p_read.blocks = 0; |
625 | max_blocks = &max_blocks_in; | |
1e608e42 | 626 | } |
3c0ef626 | 627 | if (newkeys[mode] != NULL) { |
1c14df9e | 628 | debug("set_newkeys: rekeying"); |
1e608e42 | 629 | cipher_cleanup(cc); |
3c0ef626 | 630 | enc = &newkeys[mode]->enc; |
631 | mac = &newkeys[mode]->mac; | |
632 | comp = &newkeys[mode]->comp; | |
633 | memset(mac->key, 0, mac->key_len); | |
634 | xfree(enc->name); | |
635 | xfree(enc->iv); | |
636 | xfree(enc->key); | |
637 | xfree(mac->name); | |
638 | xfree(mac->key); | |
639 | xfree(comp->name); | |
640 | xfree(newkeys[mode]); | |
641 | } | |
642 | newkeys[mode] = kex_get_newkeys(mode); | |
643 | if (newkeys[mode] == NULL) | |
644 | fatal("newkeys: no keys for mode %d", mode); | |
645 | enc = &newkeys[mode]->enc; | |
646 | mac = &newkeys[mode]->mac; | |
647 | comp = &newkeys[mode]->comp; | |
648 | if (mac->md != NULL) | |
649 | mac->enabled = 1; | |
650 | DBG(debug("cipher_init_context: %d", mode)); | |
1e608e42 | 651 | cipher_init(cc, enc->cipher, enc->key, enc->key_len, |
1b56ff3d | 652 | enc->iv, enc->block_size, crypt_type); |
2980ea68 | 653 | /* Deleting the keys does not gain extra security */ |
654 | /* memset(enc->iv, 0, enc->block_size); | |
655 | memset(enc->key, 0, enc->key_len); */ | |
34fee935 | 656 | if ((comp->type == COMP_ZLIB || |
657 | (comp->type == COMP_DELAYED && after_authentication)) && | |
658 | comp->enabled == 0) { | |
3c0ef626 | 659 | packet_init_compression(); |
660 | if (mode == MODE_OUT) | |
661 | buffer_compress_init_send(6); | |
662 | else | |
663 | buffer_compress_init_recv(); | |
664 | comp->enabled = 1; | |
665 | } | |
70791e56 | 666 | /* |
667 | * The 2^(blocksize*2) limit is too expensive for 3DES, | |
668 | * blowfish, etc, so enforce a 1GB limit for small blocksizes. | |
669 | */ | |
670 | if (enc->block_size >= 16) | |
671 | *max_blocks = (u_int64_t)1 << (enc->block_size*2); | |
672 | else | |
673 | *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; | |
674 | if (rekey_limit) | |
675 | *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); | |
3c0ef626 | 676 | } |
677 | ||
34fee935 | 678 | /* |
679 | * Delayed compression for SSH2 is enabled after authentication: | |
2e437378 | 680 | * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent, |
34fee935 | 681 | * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received. |
682 | */ | |
683 | static void | |
684 | packet_enable_delayed_compress(void) | |
685 | { | |
686 | Comp *comp = NULL; | |
687 | int mode; | |
688 | ||
689 | /* | |
690 | * Remember that we are past the authentication step, so rekeying | |
691 | * with COMP_DELAYED will turn on compression immediately. | |
692 | */ | |
693 | after_authentication = 1; | |
694 | for (mode = 0; mode < MODE_MAX; mode++) { | |
2e437378 | 695 | /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */ |
696 | if (newkeys[mode] == NULL) | |
697 | continue; | |
34fee935 | 698 | comp = &newkeys[mode]->comp; |
699 | if (comp && !comp->enabled && comp->type == COMP_DELAYED) { | |
700 | packet_init_compression(); | |
701 | if (mode == MODE_OUT) | |
702 | buffer_compress_init_send(6); | |
703 | else | |
704 | buffer_compress_init_recv(); | |
705 | comp->enabled = 1; | |
706 | } | |
707 | } | |
708 | } | |
709 | ||
3c0ef626 | 710 | /* |
711 | * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) | |
712 | */ | |
713 | static void | |
70791e56 | 714 | packet_send2_wrapped(void) |
3c0ef626 | 715 | { |
1e608e42 | 716 | u_char type, *cp, *macbuf = NULL; |
3c0ef626 | 717 | u_char padlen, pad; |
3c0ef626 | 718 | u_int packet_length = 0; |
719 | u_int i, len; | |
1b56ff3d | 720 | u_int32_t rnd = 0; |
3c0ef626 | 721 | Enc *enc = NULL; |
722 | Mac *mac = NULL; | |
723 | Comp *comp = NULL; | |
724 | int block_size; | |
725 | ||
726 | if (newkeys[MODE_OUT] != NULL) { | |
727 | enc = &newkeys[MODE_OUT]->enc; | |
728 | mac = &newkeys[MODE_OUT]->mac; | |
729 | comp = &newkeys[MODE_OUT]->comp; | |
730 | } | |
1e608e42 | 731 | block_size = enc ? enc->block_size : 8; |
3c0ef626 | 732 | |
1e608e42 | 733 | cp = buffer_ptr(&outgoing_packet); |
734 | type = cp[5]; | |
3c0ef626 | 735 | |
736 | #ifdef PACKET_DEBUG | |
737 | fprintf(stderr, "plain: "); | |
738 | buffer_dump(&outgoing_packet); | |
739 | #endif | |
740 | ||
741 | if (comp && comp->enabled) { | |
742 | len = buffer_len(&outgoing_packet); | |
743 | /* skip header, compress only payload */ | |
744 | buffer_consume(&outgoing_packet, 5); | |
745 | buffer_clear(&compression_buffer); | |
746 | buffer_compress(&outgoing_packet, &compression_buffer); | |
747 | buffer_clear(&outgoing_packet); | |
748 | buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); | |
749 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
750 | buffer_len(&compression_buffer)); | |
751 | DBG(debug("compression: raw %d compressed %d", len, | |
752 | buffer_len(&outgoing_packet))); | |
753 | } | |
754 | ||
755 | /* sizeof (packet_len + pad_len + payload) */ | |
756 | len = buffer_len(&outgoing_packet); | |
757 | ||
758 | /* | |
759 | * calc size of padding, alloc space, get random data, | |
760 | * minimum padding is 4 bytes | |
761 | */ | |
762 | padlen = block_size - (len % block_size); | |
763 | if (padlen < 4) | |
764 | padlen += block_size; | |
765 | if (extra_pad) { | |
766 | /* will wrap if extra_pad+padlen > 255 */ | |
767 | extra_pad = roundup(extra_pad, block_size); | |
768 | pad = extra_pad - ((len + padlen) % extra_pad); | |
2980ea68 | 769 | debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", |
3c0ef626 | 770 | pad, len, padlen, extra_pad); |
771 | padlen += pad; | |
772 | extra_pad = 0; | |
773 | } | |
1e608e42 | 774 | cp = buffer_append_space(&outgoing_packet, padlen); |
775 | if (enc && !send_context.plaintext) { | |
3c0ef626 | 776 | /* random padding */ |
777 | for (i = 0; i < padlen; i++) { | |
778 | if (i % 4 == 0) | |
1b56ff3d | 779 | rnd = arc4random(); |
780 | cp[i] = rnd & 0xff; | |
781 | rnd >>= 8; | |
3c0ef626 | 782 | } |
783 | } else { | |
784 | /* clear padding */ | |
785 | memset(cp, 0, padlen); | |
786 | } | |
787 | /* packet_length includes payload, padding and padding length field */ | |
788 | packet_length = buffer_len(&outgoing_packet) - 4; | |
1e608e42 | 789 | cp = buffer_ptr(&outgoing_packet); |
2e437378 | 790 | put_u32(cp, packet_length); |
1e608e42 | 791 | cp[4] = padlen; |
3c0ef626 | 792 | DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); |
793 | ||
794 | /* compute MAC over seqnr and packet(length fields, payload, padding) */ | |
795 | if (mac && mac->enabled) { | |
70791e56 | 796 | macbuf = mac_compute(mac, p_send.seqnr, |
1e608e42 | 797 | buffer_ptr(&outgoing_packet), |
3c0ef626 | 798 | buffer_len(&outgoing_packet)); |
70791e56 | 799 | DBG(debug("done calc MAC out #%d", p_send.seqnr)); |
3c0ef626 | 800 | } |
801 | /* encrypt packet and append to output buffer. */ | |
1e608e42 | 802 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); |
803 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
3c0ef626 | 804 | buffer_len(&outgoing_packet)); |
805 | /* append unencrypted MAC */ | |
806 | if (mac && mac->enabled) | |
2e437378 | 807 | buffer_append(&output, macbuf, mac->mac_len); |
3c0ef626 | 808 | #ifdef PACKET_DEBUG |
809 | fprintf(stderr, "encrypted: "); | |
810 | buffer_dump(&output); | |
811 | #endif | |
812 | /* increment sequence number for outgoing packets */ | |
70791e56 | 813 | if (++p_send.seqnr == 0) |
814 | logit("outgoing seqnr wraps around"); | |
815 | if (++p_send.packets == 0) | |
816 | if (!(datafellows & SSH_BUG_NOREKEY)) | |
817 | fatal("XXX too many packets with same key"); | |
818 | p_send.blocks += (packet_length + 4) / block_size; | |
3c0ef626 | 819 | buffer_clear(&outgoing_packet); |
820 | ||
821 | if (type == SSH2_MSG_NEWKEYS) | |
822 | set_newkeys(MODE_OUT); | |
34fee935 | 823 | else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side) |
824 | packet_enable_delayed_compress(); | |
3c0ef626 | 825 | } |
826 | ||
70791e56 | 827 | static void |
828 | packet_send2(void) | |
829 | { | |
830 | static int rekeying = 0; | |
831 | struct packet *p; | |
832 | u_char type, *cp; | |
833 | ||
834 | cp = buffer_ptr(&outgoing_packet); | |
835 | type = cp[5]; | |
836 | ||
837 | /* during rekeying we can only send key exchange messages */ | |
838 | if (rekeying) { | |
839 | if (!((type >= SSH2_MSG_TRANSPORT_MIN) && | |
840 | (type <= SSH2_MSG_TRANSPORT_MAX))) { | |
841 | debug("enqueue packet: %u", type); | |
842 | p = xmalloc(sizeof(*p)); | |
843 | p->type = type; | |
844 | memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); | |
845 | buffer_init(&outgoing_packet); | |
846 | TAILQ_INSERT_TAIL(&outgoing, p, next); | |
847 | return; | |
848 | } | |
849 | } | |
850 | ||
851 | /* rekeying starts with sending KEXINIT */ | |
852 | if (type == SSH2_MSG_KEXINIT) | |
853 | rekeying = 1; | |
854 | ||
855 | packet_send2_wrapped(); | |
856 | ||
857 | /* after a NEWKEYS message we can send the complete queue */ | |
858 | if (type == SSH2_MSG_NEWKEYS) { | |
859 | rekeying = 0; | |
860 | while ((p = TAILQ_FIRST(&outgoing))) { | |
861 | type = p->type; | |
862 | debug("dequeue packet: %u", type); | |
863 | buffer_free(&outgoing_packet); | |
864 | memcpy(&outgoing_packet, &p->payload, | |
865 | sizeof(Buffer)); | |
866 | TAILQ_REMOVE(&outgoing, p, next); | |
867 | xfree(p); | |
868 | packet_send2_wrapped(); | |
869 | } | |
870 | } | |
871 | } | |
872 | ||
3c0ef626 | 873 | void |
1e608e42 | 874 | packet_send(void) |
3c0ef626 | 875 | { |
876 | if (compat20) | |
877 | packet_send2(); | |
878 | else | |
879 | packet_send1(); | |
880 | DBG(debug("packet_send done")); | |
881 | } | |
882 | ||
883 | /* | |
884 | * Waits until a packet has been received, and returns its type. Note that | |
885 | * no other data is processed until this returns, so this function should not | |
886 | * be used during the interactive session. | |
887 | */ | |
888 | ||
889 | int | |
1e608e42 | 890 | packet_read_seqnr(u_int32_t *seqnr_p) |
3c0ef626 | 891 | { |
892 | int type, len; | |
893 | fd_set *setp; | |
894 | char buf[8192]; | |
895 | DBG(debug("packet_read()")); | |
896 | ||
2e437378 | 897 | setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS), |
3c0ef626 | 898 | sizeof(fd_mask)); |
899 | ||
900 | /* Since we are blocking, ensure that all written packets have been sent. */ | |
901 | packet_write_wait(); | |
902 | ||
903 | /* Stay in the loop until we have received a complete packet. */ | |
904 | for (;;) { | |
905 | /* Try to read a packet from the buffer. */ | |
1e608e42 | 906 | type = packet_read_poll_seqnr(seqnr_p); |
3c0ef626 | 907 | if (!compat20 && ( |
908 | type == SSH_SMSG_SUCCESS | |
909 | || type == SSH_SMSG_FAILURE | |
910 | || type == SSH_CMSG_EOF | |
911 | || type == SSH_CMSG_EXIT_CONFIRMATION)) | |
1e608e42 | 912 | packet_check_eom(); |
3c0ef626 | 913 | /* If we got a packet, return it. */ |
914 | if (type != SSH_MSG_NONE) { | |
915 | xfree(setp); | |
916 | return type; | |
917 | } | |
918 | /* | |
919 | * Otherwise, wait for some data to arrive, add it to the | |
920 | * buffer, and try again. | |
921 | */ | |
922 | memset(setp, 0, howmany(connection_in + 1, NFDBITS) * | |
923 | sizeof(fd_mask)); | |
924 | FD_SET(connection_in, setp); | |
925 | ||
926 | /* Wait for some data to arrive. */ | |
927 | while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && | |
928 | (errno == EAGAIN || errno == EINTR)) | |
929 | ; | |
930 | ||
931 | /* Read data from the socket. */ | |
932 | len = read(connection_in, buf, sizeof(buf)); | |
933 | if (len == 0) { | |
70791e56 | 934 | logit("Connection closed by %.200s", get_remote_ipaddr()); |
416fd2a8 | 935 | cleanup_exit(255); |
3c0ef626 | 936 | } |
937 | if (len < 0) | |
938 | fatal("Read from socket failed: %.100s", strerror(errno)); | |
939 | /* Append it to the buffer. */ | |
940 | packet_process_incoming(buf, len); | |
941 | } | |
942 | /* NOTREACHED */ | |
943 | } | |
944 | ||
1e608e42 | 945 | int |
946 | packet_read(void) | |
947 | { | |
948 | return packet_read_seqnr(NULL); | |
949 | } | |
950 | ||
3c0ef626 | 951 | /* |
952 | * Waits until a packet has been received, verifies that its type matches | |
953 | * that given, and gives a fatal error and exits if there is a mismatch. | |
954 | */ | |
955 | ||
956 | void | |
1e608e42 | 957 | packet_read_expect(int expected_type) |
3c0ef626 | 958 | { |
959 | int type; | |
960 | ||
1e608e42 | 961 | type = packet_read(); |
3c0ef626 | 962 | if (type != expected_type) |
963 | packet_disconnect("Protocol error: expected packet type %d, got %d", | |
964 | expected_type, type); | |
965 | } | |
966 | ||
967 | /* Checks if a full packet is available in the data received so far via | |
968 | * packet_process_incoming. If so, reads the packet; otherwise returns | |
969 | * SSH_MSG_NONE. This does not wait for data from the connection. | |
970 | * | |
971 | * SSH_MSG_DISCONNECT is handled specially here. Also, | |
972 | * SSH_MSG_IGNORE messages are skipped by this function and are never returned | |
973 | * to higher levels. | |
3c0ef626 | 974 | */ |
975 | ||
976 | static int | |
1e608e42 | 977 | packet_read_poll1(void) |
3c0ef626 | 978 | { |
979 | u_int len, padded_len; | |
1e608e42 | 980 | u_char *cp, type; |
3c0ef626 | 981 | u_int checksum, stored_checksum; |
982 | ||
983 | /* Check if input size is less than minimum packet size. */ | |
984 | if (buffer_len(&input) < 4 + 8) | |
985 | return SSH_MSG_NONE; | |
986 | /* Get length of incoming packet. */ | |
1e608e42 | 987 | cp = buffer_ptr(&input); |
2e437378 | 988 | len = get_u32(cp); |
3c0ef626 | 989 | if (len < 1 + 2 + 2 || len > 256 * 1024) |
1c14df9e | 990 | packet_disconnect("Bad packet length %u.", len); |
3c0ef626 | 991 | padded_len = (len + 8) & ~7; |
992 | ||
993 | /* Check if the packet has been entirely received. */ | |
994 | if (buffer_len(&input) < 4 + padded_len) | |
995 | return SSH_MSG_NONE; | |
996 | ||
997 | /* The entire packet is in buffer. */ | |
998 | ||
999 | /* Consume packet length. */ | |
1000 | buffer_consume(&input, 4); | |
1001 | ||
1002 | /* | |
1003 | * Cryptographic attack detector for ssh | |
1004 | * (C)1998 CORE-SDI, Buenos Aires Argentina | |
1005 | * Ariel Futoransky(futo@core-sdi.com) | |
1006 | */ | |
2e437378 | 1007 | if (!receive_context.plaintext) { |
1008 | switch (detect_attack(buffer_ptr(&input), padded_len)) { | |
1009 | case DEATTACK_DETECTED: | |
1010 | packet_disconnect("crc32 compensation attack: " | |
1011 | "network attack detected"); | |
1012 | case DEATTACK_DOS_DETECTED: | |
1013 | packet_disconnect("deattack denial of " | |
1014 | "service detected"); | |
1015 | } | |
1016 | } | |
3c0ef626 | 1017 | |
1018 | /* Decrypt data to incoming_packet. */ | |
1019 | buffer_clear(&incoming_packet); | |
1e608e42 | 1020 | cp = buffer_append_space(&incoming_packet, padded_len); |
1021 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); | |
3c0ef626 | 1022 | |
1023 | buffer_consume(&input, padded_len); | |
1024 | ||
1025 | #ifdef PACKET_DEBUG | |
1026 | fprintf(stderr, "read_poll plain: "); | |
1027 | buffer_dump(&incoming_packet); | |
1028 | #endif | |
1029 | ||
1030 | /* Compute packet checksum. */ | |
1e608e42 | 1031 | checksum = ssh_crc32(buffer_ptr(&incoming_packet), |
3c0ef626 | 1032 | buffer_len(&incoming_packet) - 4); |
1033 | ||
1034 | /* Skip padding. */ | |
1035 | buffer_consume(&incoming_packet, 8 - len % 8); | |
1036 | ||
1037 | /* Test check bytes. */ | |
1038 | if (len != buffer_len(&incoming_packet)) | |
1e608e42 | 1039 | packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", |
3c0ef626 | 1040 | len, buffer_len(&incoming_packet)); |
1041 | ||
1e608e42 | 1042 | cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; |
2e437378 | 1043 | stored_checksum = get_u32(cp); |
3c0ef626 | 1044 | if (checksum != stored_checksum) |
1045 | packet_disconnect("Corrupted check bytes on input."); | |
1046 | buffer_consume_end(&incoming_packet, 4); | |
1047 | ||
1048 | if (packet_compression) { | |
1049 | buffer_clear(&compression_buffer); | |
1050 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
1051 | buffer_clear(&incoming_packet); | |
1052 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
1053 | buffer_len(&compression_buffer)); | |
1054 | } | |
1055 | type = buffer_get_char(&incoming_packet); | |
34fee935 | 1056 | if (type < SSH_MSG_MIN || type > SSH_MSG_MAX) |
1057 | packet_disconnect("Invalid ssh1 packet type: %d", type); | |
3c0ef626 | 1058 | return type; |
1059 | } | |
1060 | ||
1061 | static int | |
1e608e42 | 1062 | packet_read_poll2(u_int32_t *seqnr_p) |
3c0ef626 | 1063 | { |
3c0ef626 | 1064 | static u_int packet_length = 0; |
1065 | u_int padlen, need; | |
1e608e42 | 1066 | u_char *macbuf, *cp, type; |
34fee935 | 1067 | u_int maclen, block_size; |
3c0ef626 | 1068 | Enc *enc = NULL; |
1069 | Mac *mac = NULL; | |
1070 | Comp *comp = NULL; | |
1071 | ||
1072 | if (newkeys[MODE_IN] != NULL) { | |
1073 | enc = &newkeys[MODE_IN]->enc; | |
1074 | mac = &newkeys[MODE_IN]->mac; | |
1075 | comp = &newkeys[MODE_IN]->comp; | |
1076 | } | |
1077 | maclen = mac && mac->enabled ? mac->mac_len : 0; | |
1e608e42 | 1078 | block_size = enc ? enc->block_size : 8; |
3c0ef626 | 1079 | |
1080 | if (packet_length == 0) { | |
1081 | /* | |
1082 | * check if input size is less than the cipher block size, | |
1083 | * decrypt first block and extract length of incoming packet | |
1084 | */ | |
1085 | if (buffer_len(&input) < block_size) | |
1086 | return SSH_MSG_NONE; | |
1087 | buffer_clear(&incoming_packet); | |
1e608e42 | 1088 | cp = buffer_append_space(&incoming_packet, block_size); |
1089 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), | |
3c0ef626 | 1090 | block_size); |
1e608e42 | 1091 | cp = buffer_ptr(&incoming_packet); |
2e437378 | 1092 | packet_length = get_u32(cp); |
3c0ef626 | 1093 | if (packet_length < 1 + 4 || packet_length > 256 * 1024) { |
70791e56 | 1094 | #ifdef PACKET_DEBUG |
3c0ef626 | 1095 | buffer_dump(&incoming_packet); |
70791e56 | 1096 | #endif |
1c14df9e | 1097 | packet_disconnect("Bad packet length %u.", packet_length); |
3c0ef626 | 1098 | } |
1c14df9e | 1099 | DBG(debug("input: packet len %u", packet_length+4)); |
3c0ef626 | 1100 | buffer_consume(&input, block_size); |
1101 | } | |
1102 | /* we have a partial packet of block_size bytes */ | |
1103 | need = 4 + packet_length - block_size; | |
1104 | DBG(debug("partial packet %d, need %d, maclen %d", block_size, | |
1105 | need, maclen)); | |
1106 | if (need % block_size != 0) | |
1107 | fatal("padding error: need %d block %d mod %d", | |
1108 | need, block_size, need % block_size); | |
1109 | /* | |
1110 | * check if the entire packet has been received and | |
1111 | * decrypt into incoming_packet | |
1112 | */ | |
1113 | if (buffer_len(&input) < need + maclen) | |
1114 | return SSH_MSG_NONE; | |
1115 | #ifdef PACKET_DEBUG | |
1116 | fprintf(stderr, "read_poll enc/full: "); | |
1117 | buffer_dump(&input); | |
1118 | #endif | |
1e608e42 | 1119 | cp = buffer_append_space(&incoming_packet, need); |
1120 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); | |
3c0ef626 | 1121 | buffer_consume(&input, need); |
1122 | /* | |
1123 | * compute MAC over seqnr and packet, | |
1124 | * increment sequence number for incoming packet | |
1125 | */ | |
1126 | if (mac && mac->enabled) { | |
70791e56 | 1127 | macbuf = mac_compute(mac, p_read.seqnr, |
1e608e42 | 1128 | buffer_ptr(&incoming_packet), |
3c0ef626 | 1129 | buffer_len(&incoming_packet)); |
1130 | if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) | |
1131 | packet_disconnect("Corrupted MAC on input."); | |
70791e56 | 1132 | DBG(debug("MAC #%d ok", p_read.seqnr)); |
3c0ef626 | 1133 | buffer_consume(&input, mac->mac_len); |
1134 | } | |
1e608e42 | 1135 | if (seqnr_p != NULL) |
70791e56 | 1136 | *seqnr_p = p_read.seqnr; |
1137 | if (++p_read.seqnr == 0) | |
1138 | logit("incoming seqnr wraps around"); | |
1139 | if (++p_read.packets == 0) | |
1140 | if (!(datafellows & SSH_BUG_NOREKEY)) | |
1141 | fatal("XXX too many packets with same key"); | |
1142 | p_read.blocks += (packet_length + 4) / block_size; | |
3c0ef626 | 1143 | |
1144 | /* get padlen */ | |
1e608e42 | 1145 | cp = buffer_ptr(&incoming_packet); |
1146 | padlen = cp[4]; | |
3c0ef626 | 1147 | DBG(debug("input: padlen %d", padlen)); |
1148 | if (padlen < 4) | |
1149 | packet_disconnect("Corrupted padlen %d on input.", padlen); | |
1150 | ||
1151 | /* skip packet size + padlen, discard padding */ | |
1152 | buffer_consume(&incoming_packet, 4 + 1); | |
1153 | buffer_consume_end(&incoming_packet, padlen); | |
1154 | ||
1155 | DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); | |
1156 | if (comp && comp->enabled) { | |
1157 | buffer_clear(&compression_buffer); | |
1158 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
1159 | buffer_clear(&incoming_packet); | |
1160 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
1161 | buffer_len(&compression_buffer)); | |
e54b3d7c | 1162 | DBG(debug("input: len after de-compress %d", |
1163 | buffer_len(&incoming_packet))); | |
3c0ef626 | 1164 | } |
1165 | /* | |
1166 | * get packet type, implies consume. | |
1167 | * return length of payload (without type field) | |
1168 | */ | |
1169 | type = buffer_get_char(&incoming_packet); | |
34fee935 | 1170 | if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN) |
1171 | packet_disconnect("Invalid ssh2 packet type: %d", type); | |
3c0ef626 | 1172 | if (type == SSH2_MSG_NEWKEYS) |
1173 | set_newkeys(MODE_IN); | |
34fee935 | 1174 | else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side) |
1175 | packet_enable_delayed_compress(); | |
3c0ef626 | 1176 | #ifdef PACKET_DEBUG |
1177 | fprintf(stderr, "read/plain[%d]:\r\n", type); | |
1178 | buffer_dump(&incoming_packet); | |
1179 | #endif | |
1180 | /* reset for next packet */ | |
1181 | packet_length = 0; | |
1182 | return type; | |
1183 | } | |
1184 | ||
1185 | int | |
1e608e42 | 1186 | packet_read_poll_seqnr(u_int32_t *seqnr_p) |
3c0ef626 | 1187 | { |
ff2d7a98 | 1188 | u_int reason, seqnr; |
3c0ef626 | 1189 | u_char type; |
1190 | char *msg; | |
1191 | ||
1192 | for (;;) { | |
1193 | if (compat20) { | |
1e608e42 | 1194 | type = packet_read_poll2(seqnr_p); |
3c0ef626 | 1195 | if (type) |
1196 | DBG(debug("received packet type %d", type)); | |
1e608e42 | 1197 | switch (type) { |
3c0ef626 | 1198 | case SSH2_MSG_IGNORE: |
1199 | break; | |
1200 | case SSH2_MSG_DEBUG: | |
1201 | packet_get_char(); | |
1202 | msg = packet_get_string(NULL); | |
1203 | debug("Remote: %.900s", msg); | |
1204 | xfree(msg); | |
1205 | msg = packet_get_string(NULL); | |
1206 | xfree(msg); | |
1207 | break; | |
1208 | case SSH2_MSG_DISCONNECT: | |
1209 | reason = packet_get_int(); | |
1210 | msg = packet_get_string(NULL); | |
70791e56 | 1211 | logit("Received disconnect from %s: %u: %.400s", |
ff2d7a98 | 1212 | get_remote_ipaddr(), reason, msg); |
3c0ef626 | 1213 | xfree(msg); |
416fd2a8 | 1214 | cleanup_exit(255); |
3c0ef626 | 1215 | break; |
1e608e42 | 1216 | case SSH2_MSG_UNIMPLEMENTED: |
1217 | seqnr = packet_get_int(); | |
ff2d7a98 | 1218 | debug("Received SSH2_MSG_UNIMPLEMENTED for %u", |
1219 | seqnr); | |
1e608e42 | 1220 | break; |
3c0ef626 | 1221 | default: |
1222 | return type; | |
3c0ef626 | 1223 | } |
1224 | } else { | |
1e608e42 | 1225 | type = packet_read_poll1(); |
1226 | switch (type) { | |
3c0ef626 | 1227 | case SSH_MSG_IGNORE: |
1228 | break; | |
1229 | case SSH_MSG_DEBUG: | |
1230 | msg = packet_get_string(NULL); | |
1231 | debug("Remote: %.900s", msg); | |
1232 | xfree(msg); | |
1233 | break; | |
1234 | case SSH_MSG_DISCONNECT: | |
1235 | msg = packet_get_string(NULL); | |
70791e56 | 1236 | logit("Received disconnect from %s: %.400s", |
ff2d7a98 | 1237 | get_remote_ipaddr(), msg); |
416fd2a8 | 1238 | cleanup_exit(255); |
3c0ef626 | 1239 | xfree(msg); |
1240 | break; | |
1241 | default: | |
1242 | if (type) | |
1243 | DBG(debug("received packet type %d", type)); | |
1244 | return type; | |
3c0ef626 | 1245 | } |
1246 | } | |
1247 | } | |
1248 | } | |
1249 | ||
1e608e42 | 1250 | int |
1251 | packet_read_poll(void) | |
1252 | { | |
1253 | return packet_read_poll_seqnr(NULL); | |
1254 | } | |
1255 | ||
3c0ef626 | 1256 | /* |
1257 | * Buffers the given amount of input characters. This is intended to be used | |
1258 | * together with packet_read_poll. | |
1259 | */ | |
1260 | ||
1261 | void | |
1262 | packet_process_incoming(const char *buf, u_int len) | |
1263 | { | |
1264 | buffer_append(&input, buf, len); | |
1265 | } | |
1266 | ||
1267 | /* Returns a character from the packet. */ | |
1268 | ||
1269 | u_int | |
1e608e42 | 1270 | packet_get_char(void) |
3c0ef626 | 1271 | { |
1272 | char ch; | |
e54b3d7c | 1273 | |
3c0ef626 | 1274 | buffer_get(&incoming_packet, &ch, 1); |
1275 | return (u_char) ch; | |
1276 | } | |
1277 | ||
1278 | /* Returns an integer from the packet data. */ | |
1279 | ||
1280 | u_int | |
1e608e42 | 1281 | packet_get_int(void) |
3c0ef626 | 1282 | { |
1283 | return buffer_get_int(&incoming_packet); | |
1284 | } | |
1285 | ||
1286 | /* | |
1287 | * Returns an arbitrary precision integer from the packet data. The integer | |
1288 | * must have been initialized before this call. | |
1289 | */ | |
1290 | ||
1291 | void | |
1e608e42 | 1292 | packet_get_bignum(BIGNUM * value) |
3c0ef626 | 1293 | { |
1e608e42 | 1294 | buffer_get_bignum(&incoming_packet, value); |
3c0ef626 | 1295 | } |
1296 | ||
1297 | void | |
1e608e42 | 1298 | packet_get_bignum2(BIGNUM * value) |
3c0ef626 | 1299 | { |
1e608e42 | 1300 | buffer_get_bignum2(&incoming_packet, value); |
3c0ef626 | 1301 | } |
1302 | ||
1e608e42 | 1303 | void * |
34fee935 | 1304 | packet_get_raw(u_int *length_ptr) |
3c0ef626 | 1305 | { |
34fee935 | 1306 | u_int bytes = buffer_len(&incoming_packet); |
e54b3d7c | 1307 | |
3c0ef626 | 1308 | if (length_ptr != NULL) |
1309 | *length_ptr = bytes; | |
1310 | return buffer_ptr(&incoming_packet); | |
1311 | } | |
1312 | ||
1313 | int | |
1314 | packet_remaining(void) | |
1315 | { | |
1316 | return buffer_len(&incoming_packet); | |
1317 | } | |
1318 | ||
1319 | /* | |
1320 | * Returns a string from the packet data. The string is allocated using | |
1321 | * xmalloc; it is the responsibility of the calling program to free it when | |
1322 | * no longer needed. The length_ptr argument may be NULL, or point to an | |
1323 | * integer into which the length of the string is stored. | |
1324 | */ | |
1325 | ||
1e608e42 | 1326 | void * |
3c0ef626 | 1327 | packet_get_string(u_int *length_ptr) |
1328 | { | |
1329 | return buffer_get_string(&incoming_packet, length_ptr); | |
1330 | } | |
1331 | ||
1332 | /* | |
1333 | * Sends a diagnostic message from the server to the client. This message | |
1334 | * can be sent at any time (but not while constructing another message). The | |
1335 | * message is printed immediately, but only if the client is being executed | |
1336 | * in verbose mode. These messages are primarily intended to ease debugging | |
1337 | * authentication problems. The length of the formatted message must not | |
1338 | * exceed 1024 bytes. This will automatically call packet_write_wait. | |
1339 | */ | |
1340 | ||
1341 | void | |
1342 | packet_send_debug(const char *fmt,...) | |
1343 | { | |
1344 | char buf[1024]; | |
1345 | va_list args; | |
1346 | ||
1347 | if (compat20 && (datafellows & SSH_BUG_DEBUG)) | |
1348 | return; | |
1349 | ||
1350 | va_start(args, fmt); | |
1351 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1352 | va_end(args); | |
1353 | ||
1354 | if (compat20) { | |
1355 | packet_start(SSH2_MSG_DEBUG); | |
1356 | packet_put_char(0); /* bool: always display */ | |
1357 | packet_put_cstring(buf); | |
1358 | packet_put_cstring(""); | |
1359 | } else { | |
1360 | packet_start(SSH_MSG_DEBUG); | |
1361 | packet_put_cstring(buf); | |
1362 | } | |
1363 | packet_send(); | |
1364 | packet_write_wait(); | |
1365 | } | |
1366 | ||
1367 | /* | |
1368 | * Logs the error plus constructs and sends a disconnect packet, closes the | |
1369 | * connection, and exits. This function never returns. The error message | |
1370 | * should not contain a newline. The length of the formatted message must | |
1371 | * not exceed 1024 bytes. | |
1372 | */ | |
1373 | ||
1374 | void | |
1375 | packet_disconnect(const char *fmt,...) | |
1376 | { | |
1377 | char buf[1024]; | |
1378 | va_list args; | |
1379 | static int disconnecting = 0; | |
e54b3d7c | 1380 | |
3c0ef626 | 1381 | if (disconnecting) /* Guard against recursive invocations. */ |
1382 | fatal("packet_disconnect called recursively."); | |
1383 | disconnecting = 1; | |
1384 | ||
1385 | /* | |
1386 | * Format the message. Note that the caller must make sure the | |
1387 | * message is of limited size. | |
1388 | */ | |
1389 | va_start(args, fmt); | |
1390 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1391 | va_end(args); | |
1392 | ||
1c14df9e | 1393 | /* Display the error locally */ |
70791e56 | 1394 | logit("Disconnecting: %.100s", buf); |
1c14df9e | 1395 | |
3c0ef626 | 1396 | /* Send the disconnect message to the other side, and wait for it to get sent. */ |
1397 | if (compat20) { | |
1398 | packet_start(SSH2_MSG_DISCONNECT); | |
1399 | packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); | |
1400 | packet_put_cstring(buf); | |
1401 | packet_put_cstring(""); | |
1402 | } else { | |
1403 | packet_start(SSH_MSG_DISCONNECT); | |
1404 | packet_put_cstring(buf); | |
1405 | } | |
1406 | packet_send(); | |
1407 | packet_write_wait(); | |
1408 | ||
1409 | /* Stop listening for connections. */ | |
1410 | channel_close_all(); | |
1411 | ||
1412 | /* Close the connection. */ | |
1413 | packet_close(); | |
416fd2a8 | 1414 | cleanup_exit(255); |
3c0ef626 | 1415 | } |
1416 | ||
1417 | /* Checks if there is any buffered output, and tries to write some of the output. */ | |
1418 | ||
1419 | void | |
1e608e42 | 1420 | packet_write_poll(void) |
3c0ef626 | 1421 | { |
1422 | int len = buffer_len(&output); | |
e54b3d7c | 1423 | |
3c0ef626 | 1424 | if (len > 0) { |
1425 | len = write(connection_out, buffer_ptr(&output), len); | |
1426 | if (len <= 0) { | |
1427 | if (errno == EAGAIN) | |
1428 | return; | |
1429 | else | |
1430 | fatal("Write failed: %.100s", strerror(errno)); | |
1431 | } | |
1432 | buffer_consume(&output, len); | |
1433 | } | |
1434 | } | |
1435 | ||
1436 | /* | |
1437 | * Calls packet_write_poll repeatedly until all pending output data has been | |
1438 | * written. | |
1439 | */ | |
1440 | ||
1441 | void | |
1e608e42 | 1442 | packet_write_wait(void) |
3c0ef626 | 1443 | { |
1444 | fd_set *setp; | |
1445 | ||
2e437378 | 1446 | setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS), |
3c0ef626 | 1447 | sizeof(fd_mask)); |
1448 | packet_write_poll(); | |
1449 | while (packet_have_data_to_write()) { | |
1450 | memset(setp, 0, howmany(connection_out + 1, NFDBITS) * | |
1451 | sizeof(fd_mask)); | |
1452 | FD_SET(connection_out, setp); | |
1453 | while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && | |
1454 | (errno == EAGAIN || errno == EINTR)) | |
1455 | ; | |
1456 | packet_write_poll(); | |
1457 | } | |
1458 | xfree(setp); | |
1459 | } | |
1460 | ||
1461 | /* Returns true if there is buffered data to write to the connection. */ | |
1462 | ||
1463 | int | |
1e608e42 | 1464 | packet_have_data_to_write(void) |
3c0ef626 | 1465 | { |
1466 | return buffer_len(&output) != 0; | |
1467 | } | |
1468 | ||
1469 | /* Returns true if there is not too much data to write to the connection. */ | |
1470 | ||
1471 | int | |
1e608e42 | 1472 | packet_not_very_much_data_to_write(void) |
3c0ef626 | 1473 | { |
1474 | if (interactive_mode) | |
1475 | return buffer_len(&output) < 16384; | |
1476 | else | |
1477 | return buffer_len(&output) < 128 * 1024; | |
1478 | } | |
1479 | ||
70791e56 | 1480 | |
1c14df9e | 1481 | static void |
1482 | packet_set_tos(int interactive) | |
1483 | { | |
416fd2a8 | 1484 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) |
1c14df9e | 1485 | int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; |
1486 | ||
1487 | if (!packet_connection_is_on_socket() || | |
1488 | !packet_connection_is_ipv4()) | |
1489 | return; | |
1490 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, | |
1491 | sizeof(tos)) < 0) | |
1492 | error("setsockopt IP_TOS %d: %.100s:", | |
1493 | tos, strerror(errno)); | |
70791e56 | 1494 | #endif |
416fd2a8 | 1495 | } |
1c14df9e | 1496 | |
3c0ef626 | 1497 | /* Informs that the current session is interactive. Sets IP flags for that. */ |
1498 | ||
1499 | void | |
1500 | packet_set_interactive(int interactive) | |
1501 | { | |
1502 | static int called = 0; | |
3c0ef626 | 1503 | |
1504 | if (called) | |
1505 | return; | |
1506 | called = 1; | |
1507 | ||
1508 | /* Record that we are in interactive mode. */ | |
1509 | interactive_mode = interactive; | |
1510 | ||
1511 | /* Only set socket options if using a socket. */ | |
1512 | if (!packet_connection_is_on_socket()) | |
70791e56 | 1513 | return; |
2e437378 | 1514 | set_nodelay(connection_in); |
1c14df9e | 1515 | packet_set_tos(interactive); |
3c0ef626 | 1516 | } |
1517 | ||
1518 | /* Returns true if the current connection is interactive. */ | |
1519 | ||
1520 | int | |
1e608e42 | 1521 | packet_is_interactive(void) |
3c0ef626 | 1522 | { |
1523 | return interactive_mode; | |
1524 | } | |
1525 | ||
1b56ff3d | 1526 | int |
70791e56 | 1527 | packet_set_maxsize(u_int s) |
3c0ef626 | 1528 | { |
1529 | static int called = 0; | |
e54b3d7c | 1530 | |
3c0ef626 | 1531 | if (called) { |
70791e56 | 1532 | logit("packet_set_maxsize: called twice: old %d new %d", |
3c0ef626 | 1533 | max_packet_size, s); |
1534 | return -1; | |
1535 | } | |
1536 | if (s < 4 * 1024 || s > 1024 * 1024) { | |
70791e56 | 1537 | logit("packet_set_maxsize: bad size %d", s); |
3c0ef626 | 1538 | return -1; |
1539 | } | |
1540 | called = 1; | |
1541 | debug("packet_set_maxsize: setting to %d", s); | |
1542 | max_packet_size = s; | |
1543 | return s; | |
1544 | } | |
1545 | ||
1546 | /* roundup current message to pad bytes */ | |
1547 | void | |
1548 | packet_add_padding(u_char pad) | |
1549 | { | |
1550 | extra_pad = pad; | |
1551 | } | |
1552 | ||
1553 | /* | |
1554 | * 9.2. Ignored Data Message | |
1555 | * | |
1556 | * byte SSH_MSG_IGNORE | |
1557 | * string data | |
1558 | * | |
1559 | * All implementations MUST understand (and ignore) this message at any | |
1560 | * time (after receiving the protocol version). No implementation is | |
1561 | * required to send them. This message can be used as an additional | |
1562 | * protection measure against advanced traffic analysis techniques. | |
1563 | */ | |
1564 | void | |
1565 | packet_send_ignore(int nbytes) | |
1566 | { | |
1b56ff3d | 1567 | u_int32_t rnd = 0; |
3c0ef626 | 1568 | int i; |
1569 | ||
1570 | packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); | |
1571 | packet_put_int(nbytes); | |
1e608e42 | 1572 | for (i = 0; i < nbytes; i++) { |
3c0ef626 | 1573 | if (i % 4 == 0) |
1b56ff3d | 1574 | rnd = arc4random(); |
2e437378 | 1575 | packet_put_char((u_char)rnd & 0xff); |
1b56ff3d | 1576 | rnd >>= 8; |
3c0ef626 | 1577 | } |
1578 | } | |
34fee935 | 1579 | int rekey_requested = 0; |
1580 | ||
1581 | void | |
1582 | packet_request_rekeying(void) | |
1583 | { | |
1584 | rekey_requested = 1; | |
1585 | } | |
70791e56 | 1586 | |
1b56ff3d | 1587 | #define MAX_PACKETS (1U<<31) |
70791e56 | 1588 | int |
1589 | packet_need_rekeying(void) | |
1590 | { | |
1591 | if (datafellows & SSH_BUG_NOREKEY) | |
1592 | return 0; | |
34fee935 | 1593 | if (rekey_requested == 1) |
1594 | { | |
1595 | rekey_requested = 0; | |
1596 | return 1; | |
1597 | } | |
70791e56 | 1598 | return |
1599 | (p_send.packets > MAX_PACKETS) || | |
1600 | (p_read.packets > MAX_PACKETS) || | |
1601 | (max_blocks_out && (p_send.blocks > max_blocks_out)) || | |
1602 | (max_blocks_in && (p_read.blocks > max_blocks_in)); | |
1603 | } | |
1604 | ||
1605 | void | |
1606 | packet_set_rekey_limit(u_int32_t bytes) | |
1607 | { | |
1608 | rekey_limit = bytes; | |
1609 | } | |
34fee935 | 1610 | |
1611 | void | |
1612 | packet_set_server(void) | |
1613 | { | |
1614 | server_side = 1; | |
1615 | } | |
1616 | ||
1617 | void | |
1618 | packet_set_authenticated(void) | |
1619 | { | |
1620 | after_authentication = 1; | |
1621 | } |