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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 file contains code implementing the packet protocol and communication | |
6 | * with the other side. This same code is used both on client and server side. | |
7 | * | |
8 | * As far as I am concerned, the code I have written for this software | |
9 | * can be used freely for any purpose. Any derived versions of this | |
10 | * software must be clearly marked as such, and if the derived work is | |
11 | * incompatible with the protocol description in the RFC file, it must be | |
12 | * called by a name other than "ssh" or "Secure Shell". | |
13 | * | |
14 | * | |
15 | * SSH2 packet format added by Markus Friedl. | |
16 | * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. | |
17 | * | |
18 | * Redistribution and use in source and binary forms, with or without | |
19 | * modification, are permitted provided that the following conditions | |
20 | * are met: | |
21 | * 1. Redistributions of source code must retain the above copyright | |
22 | * notice, this list of conditions and the following disclaimer. | |
23 | * 2. Redistributions in binary form must reproduce the above copyright | |
24 | * notice, this list of conditions and the following disclaimer in the | |
25 | * documentation and/or other materials provided with the distribution. | |
26 | * | |
27 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
28 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
29 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
30 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
31 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
32 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
33 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
34 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
35 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
36 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
37 | */ | |
38 | ||
39 | #include "includes.h" | |
665a873d | 40 | RCSID("$OpenBSD: packet.c,v 1.119 2005/07/28 17:36:22 markus Exp $"); |
0fff78ff | 41 | |
42 | #include "openbsd-compat/sys-queue.h" | |
3c0ef626 | 43 | |
44 | #include "xmalloc.h" | |
45 | #include "buffer.h" | |
46 | #include "packet.h" | |
47 | #include "bufaux.h" | |
48 | #include "crc32.h" | |
49 | #include "getput.h" | |
50 | ||
51 | #include "compress.h" | |
52 | #include "deattack.h" | |
53 | #include "channels.h" | |
54 | ||
55 | #include "compat.h" | |
56 | #include "ssh1.h" | |
57 | #include "ssh2.h" | |
58 | ||
59 | #include "cipher.h" | |
60 | #include "kex.h" | |
61 | #include "mac.h" | |
62 | #include "log.h" | |
63 | #include "canohost.h" | |
e9a17296 | 64 | #include "misc.h" |
f5799ae1 | 65 | #include "ssh.h" |
3c0ef626 | 66 | |
67 | #ifdef PACKET_DEBUG | |
68 | #define DBG(x) x | |
69 | #else | |
70 | #define DBG(x) | |
71 | #endif | |
72 | ||
73 | /* | |
74 | * This variable contains the file descriptors used for communicating with | |
75 | * the other side. connection_in is used for reading; connection_out for | |
76 | * writing. These can be the same descriptor, in which case it is assumed to | |
77 | * be a socket. | |
78 | */ | |
79 | static int connection_in = -1; | |
80 | static int connection_out = -1; | |
81 | ||
82 | /* Protocol flags for the remote side. */ | |
83 | static u_int remote_protocol_flags = 0; | |
84 | ||
85 | /* Encryption context for receiving data. This is only used for decryption. */ | |
86 | static CipherContext receive_context; | |
87 | ||
88 | /* Encryption context for sending data. This is only used for encryption. */ | |
89 | static CipherContext send_context; | |
90 | ||
91 | /* Buffer for raw input data from the socket. */ | |
700318f3 | 92 | Buffer input; |
3c0ef626 | 93 | |
94 | /* Buffer for raw output data going to the socket. */ | |
700318f3 | 95 | Buffer output; |
3c0ef626 | 96 | |
97 | /* Buffer for the partial outgoing packet being constructed. */ | |
98 | static Buffer outgoing_packet; | |
99 | ||
100 | /* Buffer for the incoming packet currently being processed. */ | |
101 | static Buffer incoming_packet; | |
102 | ||
103 | /* Scratch buffer for packet compression/decompression. */ | |
104 | static Buffer compression_buffer; | |
105 | static int compression_buffer_ready = 0; | |
106 | ||
107 | /* Flag indicating whether packet compression/decompression is enabled. */ | |
108 | static int packet_compression = 0; | |
109 | ||
110 | /* default maximum packet size */ | |
0fff78ff | 111 | u_int max_packet_size = 32768; |
3c0ef626 | 112 | |
113 | /* Flag indicating whether this module has been initialized. */ | |
114 | static int initialized = 0; | |
115 | ||
116 | /* Set to true if the connection is interactive. */ | |
117 | static int interactive_mode = 0; | |
118 | ||
665a873d | 119 | /* Set to true if we are the server side. */ |
120 | static int server_side = 0; | |
121 | ||
122 | /* Set to true if we are authenticated. */ | |
123 | static int after_authentication = 0; | |
124 | ||
3c0ef626 | 125 | /* Session key information for Encryption and MAC */ |
126 | Newkeys *newkeys[MODE_MAX]; | |
0fff78ff | 127 | static struct packet_state { |
128 | u_int32_t seqnr; | |
129 | u_int32_t packets; | |
130 | u_int64_t blocks; | |
131 | } p_read, p_send; | |
132 | ||
133 | static u_int64_t max_blocks_in, max_blocks_out; | |
134 | static u_int32_t rekey_limit; | |
3c0ef626 | 135 | |
f5799ae1 | 136 | /* Session key for protocol v1 */ |
137 | static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; | |
138 | static u_int ssh1_keylen; | |
139 | ||
3c0ef626 | 140 | /* roundup current message to extra_pad bytes */ |
141 | static u_char extra_pad = 0; | |
142 | ||
0fff78ff | 143 | struct packet { |
144 | TAILQ_ENTRY(packet) next; | |
145 | u_char type; | |
146 | Buffer payload; | |
147 | }; | |
148 | TAILQ_HEAD(, packet) outgoing; | |
149 | ||
3c0ef626 | 150 | /* |
151 | * Sets the descriptors used for communication. Disables encryption until | |
152 | * packet_set_encryption_key is called. | |
153 | */ | |
154 | void | |
155 | packet_set_connection(int fd_in, int fd_out) | |
156 | { | |
157 | Cipher *none = cipher_by_name("none"); | |
41b2f314 | 158 | |
3c0ef626 | 159 | if (none == NULL) |
160 | fatal("packet_set_connection: cannot load cipher 'none'"); | |
161 | connection_in = fd_in; | |
162 | connection_out = fd_out; | |
c9f39d2c | 163 | cipher_init(&send_context, none, (const u_char *)"", |
164 | 0, NULL, 0, CIPHER_ENCRYPT); | |
165 | cipher_init(&receive_context, none, (const u_char *)"", | |
166 | 0, NULL, 0, CIPHER_DECRYPT); | |
3c0ef626 | 167 | newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; |
168 | if (!initialized) { | |
169 | initialized = 1; | |
170 | buffer_init(&input); | |
171 | buffer_init(&output); | |
172 | buffer_init(&outgoing_packet); | |
173 | buffer_init(&incoming_packet); | |
0fff78ff | 174 | TAILQ_INIT(&outgoing); |
3c0ef626 | 175 | } |
3c0ef626 | 176 | } |
177 | ||
178 | /* Returns 1 if remote host is connected via socket, 0 if not. */ | |
179 | ||
180 | int | |
e9a17296 | 181 | packet_connection_is_on_socket(void) |
3c0ef626 | 182 | { |
183 | struct sockaddr_storage from, to; | |
184 | socklen_t fromlen, tolen; | |
185 | ||
186 | /* filedescriptors in and out are the same, so it's a socket */ | |
187 | if (connection_in == connection_out) | |
188 | return 1; | |
189 | fromlen = sizeof(from); | |
190 | memset(&from, 0, sizeof(from)); | |
191 | if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) | |
192 | return 0; | |
193 | tolen = sizeof(to); | |
194 | memset(&to, 0, sizeof(to)); | |
195 | if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
196 | return 0; | |
197 | if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) | |
198 | return 0; | |
199 | if (from.ss_family != AF_INET && from.ss_family != AF_INET6) | |
200 | return 0; | |
201 | return 1; | |
202 | } | |
203 | ||
700318f3 | 204 | /* |
205 | * Exports an IV from the CipherContext required to export the key | |
206 | * state back from the unprivileged child to the privileged parent | |
207 | * process. | |
208 | */ | |
209 | ||
210 | void | |
211 | packet_get_keyiv(int mode, u_char *iv, u_int len) | |
212 | { | |
213 | CipherContext *cc; | |
214 | ||
215 | if (mode == MODE_OUT) | |
216 | cc = &send_context; | |
217 | else | |
218 | cc = &receive_context; | |
219 | ||
220 | cipher_get_keyiv(cc, iv, len); | |
221 | } | |
222 | ||
223 | int | |
224 | packet_get_keycontext(int mode, u_char *dat) | |
225 | { | |
226 | CipherContext *cc; | |
227 | ||
228 | if (mode == MODE_OUT) | |
229 | cc = &send_context; | |
230 | else | |
231 | cc = &receive_context; | |
232 | ||
233 | return (cipher_get_keycontext(cc, dat)); | |
234 | } | |
235 | ||
236 | void | |
237 | packet_set_keycontext(int mode, u_char *dat) | |
238 | { | |
239 | CipherContext *cc; | |
240 | ||
241 | if (mode == MODE_OUT) | |
242 | cc = &send_context; | |
243 | else | |
244 | cc = &receive_context; | |
245 | ||
246 | cipher_set_keycontext(cc, dat); | |
247 | } | |
248 | ||
249 | int | |
250 | packet_get_keyiv_len(int mode) | |
251 | { | |
252 | CipherContext *cc; | |
253 | ||
254 | if (mode == MODE_OUT) | |
255 | cc = &send_context; | |
256 | else | |
257 | cc = &receive_context; | |
258 | ||
259 | return (cipher_get_keyiv_len(cc)); | |
260 | } | |
261 | void | |
262 | packet_set_iv(int mode, u_char *dat) | |
263 | { | |
264 | CipherContext *cc; | |
265 | ||
266 | if (mode == MODE_OUT) | |
267 | cc = &send_context; | |
268 | else | |
269 | cc = &receive_context; | |
270 | ||
271 | cipher_set_keyiv(cc, dat); | |
272 | } | |
273 | int | |
0fff78ff | 274 | packet_get_ssh1_cipher(void) |
700318f3 | 275 | { |
276 | return (cipher_get_number(receive_context.cipher)); | |
277 | } | |
278 | ||
0fff78ff | 279 | void |
280 | packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets) | |
700318f3 | 281 | { |
0fff78ff | 282 | struct packet_state *state; |
283 | ||
284 | state = (mode == MODE_IN) ? &p_read : &p_send; | |
285 | *seqnr = state->seqnr; | |
286 | *blocks = state->blocks; | |
287 | *packets = state->packets; | |
700318f3 | 288 | } |
289 | ||
290 | void | |
0fff78ff | 291 | packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets) |
700318f3 | 292 | { |
0fff78ff | 293 | struct packet_state *state; |
294 | ||
295 | state = (mode == MODE_IN) ? &p_read : &p_send; | |
296 | state->seqnr = seqnr; | |
297 | state->blocks = blocks; | |
298 | state->packets = packets; | |
700318f3 | 299 | } |
300 | ||
3c0ef626 | 301 | /* returns 1 if connection is via ipv4 */ |
302 | ||
303 | int | |
e9a17296 | 304 | packet_connection_is_ipv4(void) |
3c0ef626 | 305 | { |
306 | struct sockaddr_storage to; | |
307 | socklen_t tolen = sizeof(to); | |
308 | ||
309 | memset(&to, 0, sizeof(to)); | |
310 | if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
311 | return 0; | |
700318f3 | 312 | if (to.ss_family == AF_INET) |
313 | return 1; | |
314 | #ifdef IPV4_IN_IPV6 | |
cdd66111 | 315 | if (to.ss_family == AF_INET6 && |
700318f3 | 316 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) |
317 | return 1; | |
318 | #endif | |
319 | return 0; | |
3c0ef626 | 320 | } |
321 | ||
322 | /* Sets the connection into non-blocking mode. */ | |
323 | ||
324 | void | |
e9a17296 | 325 | packet_set_nonblocking(void) |
3c0ef626 | 326 | { |
327 | /* Set the socket into non-blocking mode. */ | |
c9f39d2c | 328 | set_nonblock(connection_in); |
3c0ef626 | 329 | |
c9f39d2c | 330 | if (connection_out != connection_in) |
331 | set_nonblock(connection_out); | |
3c0ef626 | 332 | } |
333 | ||
334 | /* Returns the socket used for reading. */ | |
335 | ||
336 | int | |
e9a17296 | 337 | packet_get_connection_in(void) |
3c0ef626 | 338 | { |
339 | return connection_in; | |
340 | } | |
341 | ||
342 | /* Returns the descriptor used for writing. */ | |
343 | ||
344 | int | |
e9a17296 | 345 | packet_get_connection_out(void) |
3c0ef626 | 346 | { |
347 | return connection_out; | |
348 | } | |
349 | ||
350 | /* Closes the connection and clears and frees internal data structures. */ | |
351 | ||
352 | void | |
e9a17296 | 353 | packet_close(void) |
3c0ef626 | 354 | { |
355 | if (!initialized) | |
356 | return; | |
357 | initialized = 0; | |
358 | if (connection_in == connection_out) { | |
359 | shutdown(connection_out, SHUT_RDWR); | |
360 | close(connection_out); | |
361 | } else { | |
362 | close(connection_in); | |
363 | close(connection_out); | |
364 | } | |
365 | buffer_free(&input); | |
366 | buffer_free(&output); | |
367 | buffer_free(&outgoing_packet); | |
368 | buffer_free(&incoming_packet); | |
369 | if (compression_buffer_ready) { | |
370 | buffer_free(&compression_buffer); | |
371 | buffer_compress_uninit(); | |
372 | } | |
e9a17296 | 373 | cipher_cleanup(&send_context); |
374 | cipher_cleanup(&receive_context); | |
3c0ef626 | 375 | } |
376 | ||
377 | /* Sets remote side protocol flags. */ | |
378 | ||
379 | void | |
380 | packet_set_protocol_flags(u_int protocol_flags) | |
381 | { | |
382 | remote_protocol_flags = protocol_flags; | |
383 | } | |
384 | ||
385 | /* Returns the remote protocol flags set earlier by the above function. */ | |
386 | ||
387 | u_int | |
e9a17296 | 388 | packet_get_protocol_flags(void) |
3c0ef626 | 389 | { |
390 | return remote_protocol_flags; | |
391 | } | |
392 | ||
393 | /* | |
394 | * Starts packet compression from the next packet on in both directions. | |
395 | * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. | |
396 | */ | |
397 | ||
398 | static void | |
399 | packet_init_compression(void) | |
400 | { | |
401 | if (compression_buffer_ready == 1) | |
402 | return; | |
403 | compression_buffer_ready = 1; | |
404 | buffer_init(&compression_buffer); | |
405 | } | |
406 | ||
407 | void | |
408 | packet_start_compression(int level) | |
409 | { | |
410 | if (packet_compression && !compat20) | |
411 | fatal("Compression already enabled."); | |
412 | packet_compression = 1; | |
413 | packet_init_compression(); | |
414 | buffer_compress_init_send(level); | |
415 | buffer_compress_init_recv(); | |
416 | } | |
417 | ||
418 | /* | |
419 | * Causes any further packets to be encrypted using the given key. The same | |
420 | * key is used for both sending and reception. However, both directions are | |
421 | * encrypted independently of each other. | |
422 | */ | |
f5799ae1 | 423 | |
3c0ef626 | 424 | void |
425 | packet_set_encryption_key(const u_char *key, u_int keylen, | |
426 | int number) | |
427 | { | |
428 | Cipher *cipher = cipher_by_number(number); | |
41b2f314 | 429 | |
3c0ef626 | 430 | if (cipher == NULL) |
431 | fatal("packet_set_encryption_key: unknown cipher number %d", number); | |
432 | if (keylen < 20) | |
433 | fatal("packet_set_encryption_key: keylen too small: %d", keylen); | |
f5799ae1 | 434 | if (keylen > SSH_SESSION_KEY_LENGTH) |
435 | fatal("packet_set_encryption_key: keylen too big: %d", keylen); | |
436 | memcpy(ssh1_key, key, keylen); | |
437 | ssh1_keylen = keylen; | |
e9a17296 | 438 | cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); |
439 | cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); | |
3c0ef626 | 440 | } |
441 | ||
f5799ae1 | 442 | u_int |
443 | packet_get_encryption_key(u_char *key) | |
444 | { | |
445 | if (key == NULL) | |
446 | return (ssh1_keylen); | |
447 | memcpy(key, ssh1_key, ssh1_keylen); | |
448 | return (ssh1_keylen); | |
449 | } | |
450 | ||
3c0ef626 | 451 | /* Start constructing a packet to send. */ |
452 | void | |
453 | packet_start(u_char type) | |
454 | { | |
455 | u_char buf[9]; | |
456 | int len; | |
457 | ||
458 | DBG(debug("packet_start[%d]", type)); | |
459 | len = compat20 ? 6 : 9; | |
460 | memset(buf, 0, len - 1); | |
461 | buf[len - 1] = type; | |
462 | buffer_clear(&outgoing_packet); | |
463 | buffer_append(&outgoing_packet, buf, len); | |
464 | } | |
465 | ||
466 | /* Append payload. */ | |
467 | void | |
468 | packet_put_char(int value) | |
469 | { | |
470 | char ch = value; | |
41b2f314 | 471 | |
3c0ef626 | 472 | buffer_append(&outgoing_packet, &ch, 1); |
473 | } | |
474 | void | |
475 | packet_put_int(u_int value) | |
476 | { | |
477 | buffer_put_int(&outgoing_packet, value); | |
478 | } | |
479 | void | |
e9a17296 | 480 | packet_put_string(const void *buf, u_int len) |
3c0ef626 | 481 | { |
482 | buffer_put_string(&outgoing_packet, buf, len); | |
483 | } | |
484 | void | |
485 | packet_put_cstring(const char *str) | |
486 | { | |
487 | buffer_put_cstring(&outgoing_packet, str); | |
488 | } | |
489 | void | |
e9a17296 | 490 | packet_put_raw(const void *buf, u_int len) |
3c0ef626 | 491 | { |
492 | buffer_append(&outgoing_packet, buf, len); | |
493 | } | |
494 | void | |
495 | packet_put_bignum(BIGNUM * value) | |
496 | { | |
497 | buffer_put_bignum(&outgoing_packet, value); | |
498 | } | |
499 | void | |
500 | packet_put_bignum2(BIGNUM * value) | |
501 | { | |
502 | buffer_put_bignum2(&outgoing_packet, value); | |
503 | } | |
504 | ||
505 | /* | |
506 | * Finalizes and sends the packet. If the encryption key has been set, | |
507 | * encrypts the packet before sending. | |
508 | */ | |
509 | ||
510 | static void | |
511 | packet_send1(void) | |
512 | { | |
e9a17296 | 513 | u_char buf[8], *cp; |
3c0ef626 | 514 | int i, padding, len; |
515 | u_int checksum; | |
c9f39d2c | 516 | u_int32_t rnd = 0; |
3c0ef626 | 517 | |
518 | /* | |
519 | * If using packet compression, compress the payload of the outgoing | |
520 | * packet. | |
521 | */ | |
522 | if (packet_compression) { | |
523 | buffer_clear(&compression_buffer); | |
524 | /* Skip padding. */ | |
525 | buffer_consume(&outgoing_packet, 8); | |
526 | /* padding */ | |
527 | buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); | |
528 | buffer_compress(&outgoing_packet, &compression_buffer); | |
529 | buffer_clear(&outgoing_packet); | |
530 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
e9a17296 | 531 | buffer_len(&compression_buffer)); |
3c0ef626 | 532 | } |
533 | /* Compute packet length without padding (add checksum, remove padding). */ | |
534 | len = buffer_len(&outgoing_packet) + 4 - 8; | |
535 | ||
536 | /* Insert padding. Initialized to zero in packet_start1() */ | |
537 | padding = 8 - len % 8; | |
e9a17296 | 538 | if (!send_context.plaintext) { |
3c0ef626 | 539 | cp = buffer_ptr(&outgoing_packet); |
540 | for (i = 0; i < padding; i++) { | |
541 | if (i % 4 == 0) | |
c9f39d2c | 542 | rnd = arc4random(); |
543 | cp[7 - i] = rnd & 0xff; | |
544 | rnd >>= 8; | |
3c0ef626 | 545 | } |
546 | } | |
547 | buffer_consume(&outgoing_packet, 8 - padding); | |
548 | ||
549 | /* Add check bytes. */ | |
e9a17296 | 550 | checksum = ssh_crc32(buffer_ptr(&outgoing_packet), |
3c0ef626 | 551 | buffer_len(&outgoing_packet)); |
552 | PUT_32BIT(buf, checksum); | |
553 | buffer_append(&outgoing_packet, buf, 4); | |
554 | ||
555 | #ifdef PACKET_DEBUG | |
556 | fprintf(stderr, "packet_send plain: "); | |
557 | buffer_dump(&outgoing_packet); | |
558 | #endif | |
559 | ||
560 | /* Append to output. */ | |
561 | PUT_32BIT(buf, len); | |
562 | buffer_append(&output, buf, 4); | |
e9a17296 | 563 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); |
564 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
565 | buffer_len(&outgoing_packet)); | |
3c0ef626 | 566 | |
567 | #ifdef PACKET_DEBUG | |
568 | fprintf(stderr, "encrypted: "); | |
569 | buffer_dump(&output); | |
570 | #endif | |
571 | ||
572 | buffer_clear(&outgoing_packet); | |
573 | ||
574 | /* | |
575 | * Note that the packet is now only buffered in output. It won\'t be | |
576 | * actually sent until packet_write_wait or packet_write_poll is | |
577 | * called. | |
578 | */ | |
579 | } | |
580 | ||
700318f3 | 581 | void |
3c0ef626 | 582 | set_newkeys(int mode) |
583 | { | |
584 | Enc *enc; | |
585 | Mac *mac; | |
586 | Comp *comp; | |
587 | CipherContext *cc; | |
0fff78ff | 588 | u_int64_t *max_blocks; |
c9f39d2c | 589 | int crypt_type; |
3c0ef626 | 590 | |
6a9b3198 | 591 | debug2("set_newkeys: mode %d", mode); |
3c0ef626 | 592 | |
e9a17296 | 593 | if (mode == MODE_OUT) { |
594 | cc = &send_context; | |
c9f39d2c | 595 | crypt_type = CIPHER_ENCRYPT; |
0fff78ff | 596 | p_send.packets = p_send.blocks = 0; |
597 | max_blocks = &max_blocks_out; | |
e9a17296 | 598 | } else { |
599 | cc = &receive_context; | |
c9f39d2c | 600 | crypt_type = CIPHER_DECRYPT; |
0fff78ff | 601 | p_read.packets = p_read.blocks = 0; |
602 | max_blocks = &max_blocks_in; | |
e9a17296 | 603 | } |
3c0ef626 | 604 | if (newkeys[mode] != NULL) { |
6a9b3198 | 605 | debug("set_newkeys: rekeying"); |
e9a17296 | 606 | cipher_cleanup(cc); |
3c0ef626 | 607 | enc = &newkeys[mode]->enc; |
608 | mac = &newkeys[mode]->mac; | |
609 | comp = &newkeys[mode]->comp; | |
610 | memset(mac->key, 0, mac->key_len); | |
611 | xfree(enc->name); | |
612 | xfree(enc->iv); | |
613 | xfree(enc->key); | |
614 | xfree(mac->name); | |
615 | xfree(mac->key); | |
616 | xfree(comp->name); | |
617 | xfree(newkeys[mode]); | |
618 | } | |
619 | newkeys[mode] = kex_get_newkeys(mode); | |
620 | if (newkeys[mode] == NULL) | |
621 | fatal("newkeys: no keys for mode %d", mode); | |
622 | enc = &newkeys[mode]->enc; | |
623 | mac = &newkeys[mode]->mac; | |
624 | comp = &newkeys[mode]->comp; | |
625 | if (mac->md != NULL) | |
626 | mac->enabled = 1; | |
627 | DBG(debug("cipher_init_context: %d", mode)); | |
e9a17296 | 628 | cipher_init(cc, enc->cipher, enc->key, enc->key_len, |
c9f39d2c | 629 | enc->iv, enc->block_size, crypt_type); |
700318f3 | 630 | /* Deleting the keys does not gain extra security */ |
631 | /* memset(enc->iv, 0, enc->block_size); | |
632 | memset(enc->key, 0, enc->key_len); */ | |
665a873d | 633 | if ((comp->type == COMP_ZLIB || |
634 | (comp->type == COMP_DELAYED && after_authentication)) && | |
635 | comp->enabled == 0) { | |
3c0ef626 | 636 | packet_init_compression(); |
637 | if (mode == MODE_OUT) | |
638 | buffer_compress_init_send(6); | |
639 | else | |
640 | buffer_compress_init_recv(); | |
641 | comp->enabled = 1; | |
642 | } | |
0fff78ff | 643 | /* |
644 | * The 2^(blocksize*2) limit is too expensive for 3DES, | |
645 | * blowfish, etc, so enforce a 1GB limit for small blocksizes. | |
646 | */ | |
647 | if (enc->block_size >= 16) | |
648 | *max_blocks = (u_int64_t)1 << (enc->block_size*2); | |
649 | else | |
650 | *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; | |
651 | if (rekey_limit) | |
652 | *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); | |
3c0ef626 | 653 | } |
654 | ||
665a873d | 655 | /* |
656 | * Delayed compression for SSH2 is enabled after authentication: | |
657 | * This happans on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent, | |
658 | * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received. | |
659 | */ | |
660 | static void | |
661 | packet_enable_delayed_compress(void) | |
662 | { | |
663 | Comp *comp = NULL; | |
664 | int mode; | |
665 | ||
666 | /* | |
667 | * Remember that we are past the authentication step, so rekeying | |
668 | * with COMP_DELAYED will turn on compression immediately. | |
669 | */ | |
670 | after_authentication = 1; | |
671 | for (mode = 0; mode < MODE_MAX; mode++) { | |
672 | comp = &newkeys[mode]->comp; | |
673 | if (comp && !comp->enabled && comp->type == COMP_DELAYED) { | |
674 | packet_init_compression(); | |
675 | if (mode == MODE_OUT) | |
676 | buffer_compress_init_send(6); | |
677 | else | |
678 | buffer_compress_init_recv(); | |
679 | comp->enabled = 1; | |
680 | } | |
681 | } | |
682 | } | |
683 | ||
3c0ef626 | 684 | /* |
685 | * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) | |
686 | */ | |
687 | static void | |
0fff78ff | 688 | packet_send2_wrapped(void) |
3c0ef626 | 689 | { |
e9a17296 | 690 | u_char type, *cp, *macbuf = NULL; |
3c0ef626 | 691 | u_char padlen, pad; |
3c0ef626 | 692 | u_int packet_length = 0; |
693 | u_int i, len; | |
c9f39d2c | 694 | u_int32_t rnd = 0; |
3c0ef626 | 695 | Enc *enc = NULL; |
696 | Mac *mac = NULL; | |
697 | Comp *comp = NULL; | |
698 | int block_size; | |
699 | ||
700 | if (newkeys[MODE_OUT] != NULL) { | |
701 | enc = &newkeys[MODE_OUT]->enc; | |
702 | mac = &newkeys[MODE_OUT]->mac; | |
703 | comp = &newkeys[MODE_OUT]->comp; | |
704 | } | |
e9a17296 | 705 | block_size = enc ? enc->block_size : 8; |
3c0ef626 | 706 | |
e9a17296 | 707 | cp = buffer_ptr(&outgoing_packet); |
708 | type = cp[5]; | |
3c0ef626 | 709 | |
710 | #ifdef PACKET_DEBUG | |
711 | fprintf(stderr, "plain: "); | |
712 | buffer_dump(&outgoing_packet); | |
713 | #endif | |
714 | ||
715 | if (comp && comp->enabled) { | |
716 | len = buffer_len(&outgoing_packet); | |
717 | /* skip header, compress only payload */ | |
718 | buffer_consume(&outgoing_packet, 5); | |
719 | buffer_clear(&compression_buffer); | |
720 | buffer_compress(&outgoing_packet, &compression_buffer); | |
721 | buffer_clear(&outgoing_packet); | |
722 | buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); | |
723 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
724 | buffer_len(&compression_buffer)); | |
725 | DBG(debug("compression: raw %d compressed %d", len, | |
726 | buffer_len(&outgoing_packet))); | |
727 | } | |
728 | ||
729 | /* sizeof (packet_len + pad_len + payload) */ | |
730 | len = buffer_len(&outgoing_packet); | |
731 | ||
732 | /* | |
733 | * calc size of padding, alloc space, get random data, | |
734 | * minimum padding is 4 bytes | |
735 | */ | |
736 | padlen = block_size - (len % block_size); | |
737 | if (padlen < 4) | |
738 | padlen += block_size; | |
739 | if (extra_pad) { | |
740 | /* will wrap if extra_pad+padlen > 255 */ | |
741 | extra_pad = roundup(extra_pad, block_size); | |
742 | pad = extra_pad - ((len + padlen) % extra_pad); | |
700318f3 | 743 | debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", |
3c0ef626 | 744 | pad, len, padlen, extra_pad); |
745 | padlen += pad; | |
746 | extra_pad = 0; | |
747 | } | |
e9a17296 | 748 | cp = buffer_append_space(&outgoing_packet, padlen); |
749 | if (enc && !send_context.plaintext) { | |
3c0ef626 | 750 | /* random padding */ |
751 | for (i = 0; i < padlen; i++) { | |
752 | if (i % 4 == 0) | |
c9f39d2c | 753 | rnd = arc4random(); |
754 | cp[i] = rnd & 0xff; | |
755 | rnd >>= 8; | |
3c0ef626 | 756 | } |
757 | } else { | |
758 | /* clear padding */ | |
759 | memset(cp, 0, padlen); | |
760 | } | |
761 | /* packet_length includes payload, padding and padding length field */ | |
762 | packet_length = buffer_len(&outgoing_packet) - 4; | |
e9a17296 | 763 | cp = buffer_ptr(&outgoing_packet); |
764 | PUT_32BIT(cp, packet_length); | |
765 | cp[4] = padlen; | |
3c0ef626 | 766 | DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); |
767 | ||
768 | /* compute MAC over seqnr and packet(length fields, payload, padding) */ | |
769 | if (mac && mac->enabled) { | |
0fff78ff | 770 | macbuf = mac_compute(mac, p_send.seqnr, |
e9a17296 | 771 | buffer_ptr(&outgoing_packet), |
3c0ef626 | 772 | buffer_len(&outgoing_packet)); |
0fff78ff | 773 | DBG(debug("done calc MAC out #%d", p_send.seqnr)); |
3c0ef626 | 774 | } |
775 | /* encrypt packet and append to output buffer. */ | |
e9a17296 | 776 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); |
777 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
3c0ef626 | 778 | buffer_len(&outgoing_packet)); |
779 | /* append unencrypted MAC */ | |
780 | if (mac && mac->enabled) | |
781 | buffer_append(&output, (char *)macbuf, mac->mac_len); | |
782 | #ifdef PACKET_DEBUG | |
783 | fprintf(stderr, "encrypted: "); | |
784 | buffer_dump(&output); | |
785 | #endif | |
786 | /* increment sequence number for outgoing packets */ | |
0fff78ff | 787 | if (++p_send.seqnr == 0) |
788 | logit("outgoing seqnr wraps around"); | |
789 | if (++p_send.packets == 0) | |
790 | if (!(datafellows & SSH_BUG_NOREKEY)) | |
791 | fatal("XXX too many packets with same key"); | |
792 | p_send.blocks += (packet_length + 4) / block_size; | |
3c0ef626 | 793 | buffer_clear(&outgoing_packet); |
794 | ||
795 | if (type == SSH2_MSG_NEWKEYS) | |
796 | set_newkeys(MODE_OUT); | |
665a873d | 797 | else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side) |
798 | packet_enable_delayed_compress(); | |
3c0ef626 | 799 | } |
800 | ||
0fff78ff | 801 | static void |
802 | packet_send2(void) | |
803 | { | |
804 | static int rekeying = 0; | |
805 | struct packet *p; | |
806 | u_char type, *cp; | |
807 | ||
808 | cp = buffer_ptr(&outgoing_packet); | |
809 | type = cp[5]; | |
810 | ||
811 | /* during rekeying we can only send key exchange messages */ | |
812 | if (rekeying) { | |
813 | if (!((type >= SSH2_MSG_TRANSPORT_MIN) && | |
814 | (type <= SSH2_MSG_TRANSPORT_MAX))) { | |
815 | debug("enqueue packet: %u", type); | |
816 | p = xmalloc(sizeof(*p)); | |
817 | p->type = type; | |
818 | memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); | |
819 | buffer_init(&outgoing_packet); | |
820 | TAILQ_INSERT_TAIL(&outgoing, p, next); | |
821 | return; | |
822 | } | |
823 | } | |
824 | ||
825 | /* rekeying starts with sending KEXINIT */ | |
826 | if (type == SSH2_MSG_KEXINIT) | |
827 | rekeying = 1; | |
828 | ||
829 | packet_send2_wrapped(); | |
830 | ||
831 | /* after a NEWKEYS message we can send the complete queue */ | |
832 | if (type == SSH2_MSG_NEWKEYS) { | |
833 | rekeying = 0; | |
834 | while ((p = TAILQ_FIRST(&outgoing))) { | |
835 | type = p->type; | |
836 | debug("dequeue packet: %u", type); | |
837 | buffer_free(&outgoing_packet); | |
838 | memcpy(&outgoing_packet, &p->payload, | |
839 | sizeof(Buffer)); | |
840 | TAILQ_REMOVE(&outgoing, p, next); | |
841 | xfree(p); | |
842 | packet_send2_wrapped(); | |
843 | } | |
844 | } | |
845 | } | |
846 | ||
3c0ef626 | 847 | void |
e9a17296 | 848 | packet_send(void) |
3c0ef626 | 849 | { |
850 | if (compat20) | |
851 | packet_send2(); | |
852 | else | |
853 | packet_send1(); | |
854 | DBG(debug("packet_send done")); | |
855 | } | |
856 | ||
857 | /* | |
858 | * Waits until a packet has been received, and returns its type. Note that | |
859 | * no other data is processed until this returns, so this function should not | |
860 | * be used during the interactive session. | |
861 | */ | |
862 | ||
863 | int | |
e9a17296 | 864 | packet_read_seqnr(u_int32_t *seqnr_p) |
3c0ef626 | 865 | { |
866 | int type, len; | |
867 | fd_set *setp; | |
868 | char buf[8192]; | |
869 | DBG(debug("packet_read()")); | |
870 | ||
871 | setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * | |
872 | sizeof(fd_mask)); | |
873 | ||
874 | /* Since we are blocking, ensure that all written packets have been sent. */ | |
875 | packet_write_wait(); | |
876 | ||
877 | /* Stay in the loop until we have received a complete packet. */ | |
878 | for (;;) { | |
879 | /* Try to read a packet from the buffer. */ | |
e9a17296 | 880 | type = packet_read_poll_seqnr(seqnr_p); |
3c0ef626 | 881 | if (!compat20 && ( |
882 | type == SSH_SMSG_SUCCESS | |
883 | || type == SSH_SMSG_FAILURE | |
884 | || type == SSH_CMSG_EOF | |
885 | || type == SSH_CMSG_EXIT_CONFIRMATION)) | |
e9a17296 | 886 | packet_check_eom(); |
3c0ef626 | 887 | /* If we got a packet, return it. */ |
888 | if (type != SSH_MSG_NONE) { | |
889 | xfree(setp); | |
890 | return type; | |
891 | } | |
892 | /* | |
893 | * Otherwise, wait for some data to arrive, add it to the | |
894 | * buffer, and try again. | |
895 | */ | |
896 | memset(setp, 0, howmany(connection_in + 1, NFDBITS) * | |
897 | sizeof(fd_mask)); | |
898 | FD_SET(connection_in, setp); | |
899 | ||
900 | /* Wait for some data to arrive. */ | |
901 | while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && | |
902 | (errno == EAGAIN || errno == EINTR)) | |
903 | ; | |
904 | ||
905 | /* Read data from the socket. */ | |
906 | len = read(connection_in, buf, sizeof(buf)); | |
907 | if (len == 0) { | |
0fff78ff | 908 | logit("Connection closed by %.200s", get_remote_ipaddr()); |
cdd66111 | 909 | cleanup_exit(255); |
3c0ef626 | 910 | } |
911 | if (len < 0) | |
912 | fatal("Read from socket failed: %.100s", strerror(errno)); | |
913 | /* Append it to the buffer. */ | |
914 | packet_process_incoming(buf, len); | |
915 | } | |
916 | /* NOTREACHED */ | |
917 | } | |
918 | ||
e9a17296 | 919 | int |
920 | packet_read(void) | |
921 | { | |
922 | return packet_read_seqnr(NULL); | |
923 | } | |
924 | ||
3c0ef626 | 925 | /* |
926 | * Waits until a packet has been received, verifies that its type matches | |
927 | * that given, and gives a fatal error and exits if there is a mismatch. | |
928 | */ | |
929 | ||
930 | void | |
e9a17296 | 931 | packet_read_expect(int expected_type) |
3c0ef626 | 932 | { |
933 | int type; | |
934 | ||
e9a17296 | 935 | type = packet_read(); |
3c0ef626 | 936 | if (type != expected_type) |
937 | packet_disconnect("Protocol error: expected packet type %d, got %d", | |
938 | expected_type, type); | |
939 | } | |
940 | ||
941 | /* Checks if a full packet is available in the data received so far via | |
942 | * packet_process_incoming. If so, reads the packet; otherwise returns | |
943 | * SSH_MSG_NONE. This does not wait for data from the connection. | |
944 | * | |
945 | * SSH_MSG_DISCONNECT is handled specially here. Also, | |
946 | * SSH_MSG_IGNORE messages are skipped by this function and are never returned | |
947 | * to higher levels. | |
3c0ef626 | 948 | */ |
949 | ||
950 | static int | |
e9a17296 | 951 | packet_read_poll1(void) |
3c0ef626 | 952 | { |
953 | u_int len, padded_len; | |
e9a17296 | 954 | u_char *cp, type; |
3c0ef626 | 955 | u_int checksum, stored_checksum; |
956 | ||
957 | /* Check if input size is less than minimum packet size. */ | |
958 | if (buffer_len(&input) < 4 + 8) | |
959 | return SSH_MSG_NONE; | |
960 | /* Get length of incoming packet. */ | |
e9a17296 | 961 | cp = buffer_ptr(&input); |
962 | len = GET_32BIT(cp); | |
3c0ef626 | 963 | if (len < 1 + 2 + 2 || len > 256 * 1024) |
6a9b3198 | 964 | packet_disconnect("Bad packet length %u.", len); |
3c0ef626 | 965 | padded_len = (len + 8) & ~7; |
966 | ||
967 | /* Check if the packet has been entirely received. */ | |
968 | if (buffer_len(&input) < 4 + padded_len) | |
969 | return SSH_MSG_NONE; | |
970 | ||
971 | /* The entire packet is in buffer. */ | |
972 | ||
973 | /* Consume packet length. */ | |
974 | buffer_consume(&input, 4); | |
975 | ||
976 | /* | |
977 | * Cryptographic attack detector for ssh | |
978 | * (C)1998 CORE-SDI, Buenos Aires Argentina | |
979 | * Ariel Futoransky(futo@core-sdi.com) | |
980 | */ | |
e9a17296 | 981 | if (!receive_context.plaintext && |
3c0ef626 | 982 | detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) |
983 | packet_disconnect("crc32 compensation attack: network attack detected"); | |
984 | ||
985 | /* Decrypt data to incoming_packet. */ | |
986 | buffer_clear(&incoming_packet); | |
e9a17296 | 987 | cp = buffer_append_space(&incoming_packet, padded_len); |
988 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); | |
3c0ef626 | 989 | |
990 | buffer_consume(&input, padded_len); | |
991 | ||
992 | #ifdef PACKET_DEBUG | |
993 | fprintf(stderr, "read_poll plain: "); | |
994 | buffer_dump(&incoming_packet); | |
995 | #endif | |
996 | ||
997 | /* Compute packet checksum. */ | |
e9a17296 | 998 | checksum = ssh_crc32(buffer_ptr(&incoming_packet), |
3c0ef626 | 999 | buffer_len(&incoming_packet) - 4); |
1000 | ||
1001 | /* Skip padding. */ | |
1002 | buffer_consume(&incoming_packet, 8 - len % 8); | |
1003 | ||
1004 | /* Test check bytes. */ | |
1005 | if (len != buffer_len(&incoming_packet)) | |
e9a17296 | 1006 | packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", |
3c0ef626 | 1007 | len, buffer_len(&incoming_packet)); |
1008 | ||
e9a17296 | 1009 | cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; |
1010 | stored_checksum = GET_32BIT(cp); | |
3c0ef626 | 1011 | if (checksum != stored_checksum) |
1012 | packet_disconnect("Corrupted check bytes on input."); | |
1013 | buffer_consume_end(&incoming_packet, 4); | |
1014 | ||
1015 | if (packet_compression) { | |
1016 | buffer_clear(&compression_buffer); | |
1017 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
1018 | buffer_clear(&incoming_packet); | |
1019 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
1020 | buffer_len(&compression_buffer)); | |
1021 | } | |
1022 | type = buffer_get_char(&incoming_packet); | |
996d5e62 | 1023 | if (type < SSH_MSG_MIN || type > SSH_MSG_MAX) |
1024 | packet_disconnect("Invalid ssh1 packet type: %d", type); | |
3c0ef626 | 1025 | return type; |
1026 | } | |
1027 | ||
1028 | static int | |
e9a17296 | 1029 | packet_read_poll2(u_int32_t *seqnr_p) |
3c0ef626 | 1030 | { |
3c0ef626 | 1031 | static u_int packet_length = 0; |
1032 | u_int padlen, need; | |
e9a17296 | 1033 | u_char *macbuf, *cp, type; |
665a873d | 1034 | u_int maclen, block_size; |
3c0ef626 | 1035 | Enc *enc = NULL; |
1036 | Mac *mac = NULL; | |
1037 | Comp *comp = NULL; | |
1038 | ||
1039 | if (newkeys[MODE_IN] != NULL) { | |
1040 | enc = &newkeys[MODE_IN]->enc; | |
1041 | mac = &newkeys[MODE_IN]->mac; | |
1042 | comp = &newkeys[MODE_IN]->comp; | |
1043 | } | |
1044 | maclen = mac && mac->enabled ? mac->mac_len : 0; | |
e9a17296 | 1045 | block_size = enc ? enc->block_size : 8; |
3c0ef626 | 1046 | |
1047 | if (packet_length == 0) { | |
1048 | /* | |
1049 | * check if input size is less than the cipher block size, | |
1050 | * decrypt first block and extract length of incoming packet | |
1051 | */ | |
1052 | if (buffer_len(&input) < block_size) | |
1053 | return SSH_MSG_NONE; | |
1054 | buffer_clear(&incoming_packet); | |
e9a17296 | 1055 | cp = buffer_append_space(&incoming_packet, block_size); |
1056 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), | |
3c0ef626 | 1057 | block_size); |
e9a17296 | 1058 | cp = buffer_ptr(&incoming_packet); |
1059 | packet_length = GET_32BIT(cp); | |
3c0ef626 | 1060 | if (packet_length < 1 + 4 || packet_length > 256 * 1024) { |
acc3d05e | 1061 | #ifdef PACKET_DEBUG |
3c0ef626 | 1062 | buffer_dump(&incoming_packet); |
acc3d05e | 1063 | #endif |
6a9b3198 | 1064 | packet_disconnect("Bad packet length %u.", packet_length); |
3c0ef626 | 1065 | } |
6a9b3198 | 1066 | DBG(debug("input: packet len %u", packet_length+4)); |
3c0ef626 | 1067 | buffer_consume(&input, block_size); |
1068 | } | |
1069 | /* we have a partial packet of block_size bytes */ | |
1070 | need = 4 + packet_length - block_size; | |
1071 | DBG(debug("partial packet %d, need %d, maclen %d", block_size, | |
1072 | need, maclen)); | |
1073 | if (need % block_size != 0) | |
1074 | fatal("padding error: need %d block %d mod %d", | |
1075 | need, block_size, need % block_size); | |
1076 | /* | |
1077 | * check if the entire packet has been received and | |
1078 | * decrypt into incoming_packet | |
1079 | */ | |
1080 | if (buffer_len(&input) < need + maclen) | |
1081 | return SSH_MSG_NONE; | |
1082 | #ifdef PACKET_DEBUG | |
1083 | fprintf(stderr, "read_poll enc/full: "); | |
1084 | buffer_dump(&input); | |
1085 | #endif | |
e9a17296 | 1086 | cp = buffer_append_space(&incoming_packet, need); |
1087 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); | |
3c0ef626 | 1088 | buffer_consume(&input, need); |
1089 | /* | |
1090 | * compute MAC over seqnr and packet, | |
1091 | * increment sequence number for incoming packet | |
1092 | */ | |
1093 | if (mac && mac->enabled) { | |
0fff78ff | 1094 | macbuf = mac_compute(mac, p_read.seqnr, |
e9a17296 | 1095 | buffer_ptr(&incoming_packet), |
3c0ef626 | 1096 | buffer_len(&incoming_packet)); |
1097 | if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) | |
1098 | packet_disconnect("Corrupted MAC on input."); | |
0fff78ff | 1099 | DBG(debug("MAC #%d ok", p_read.seqnr)); |
3c0ef626 | 1100 | buffer_consume(&input, mac->mac_len); |
1101 | } | |
e9a17296 | 1102 | if (seqnr_p != NULL) |
0fff78ff | 1103 | *seqnr_p = p_read.seqnr; |
1104 | if (++p_read.seqnr == 0) | |
1105 | logit("incoming seqnr wraps around"); | |
1106 | if (++p_read.packets == 0) | |
1107 | if (!(datafellows & SSH_BUG_NOREKEY)) | |
1108 | fatal("XXX too many packets with same key"); | |
1109 | p_read.blocks += (packet_length + 4) / block_size; | |
3c0ef626 | 1110 | |
1111 | /* get padlen */ | |
e9a17296 | 1112 | cp = buffer_ptr(&incoming_packet); |
1113 | padlen = cp[4]; | |
3c0ef626 | 1114 | DBG(debug("input: padlen %d", padlen)); |
1115 | if (padlen < 4) | |
1116 | packet_disconnect("Corrupted padlen %d on input.", padlen); | |
1117 | ||
1118 | /* skip packet size + padlen, discard padding */ | |
1119 | buffer_consume(&incoming_packet, 4 + 1); | |
1120 | buffer_consume_end(&incoming_packet, padlen); | |
1121 | ||
1122 | DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); | |
1123 | if (comp && comp->enabled) { | |
1124 | buffer_clear(&compression_buffer); | |
1125 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
1126 | buffer_clear(&incoming_packet); | |
1127 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
1128 | buffer_len(&compression_buffer)); | |
41b2f314 | 1129 | DBG(debug("input: len after de-compress %d", |
1130 | buffer_len(&incoming_packet))); | |
3c0ef626 | 1131 | } |
1132 | /* | |
1133 | * get packet type, implies consume. | |
1134 | * return length of payload (without type field) | |
1135 | */ | |
1136 | type = buffer_get_char(&incoming_packet); | |
996d5e62 | 1137 | if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN) |
1138 | packet_disconnect("Invalid ssh2 packet type: %d", type); | |
3c0ef626 | 1139 | if (type == SSH2_MSG_NEWKEYS) |
1140 | set_newkeys(MODE_IN); | |
665a873d | 1141 | else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side) |
1142 | packet_enable_delayed_compress(); | |
3c0ef626 | 1143 | #ifdef PACKET_DEBUG |
1144 | fprintf(stderr, "read/plain[%d]:\r\n", type); | |
1145 | buffer_dump(&incoming_packet); | |
1146 | #endif | |
1147 | /* reset for next packet */ | |
1148 | packet_length = 0; | |
1149 | return type; | |
1150 | } | |
1151 | ||
1152 | int | |
e9a17296 | 1153 | packet_read_poll_seqnr(u_int32_t *seqnr_p) |
3c0ef626 | 1154 | { |
680cee3b | 1155 | u_int reason, seqnr; |
3c0ef626 | 1156 | u_char type; |
1157 | char *msg; | |
1158 | ||
1159 | for (;;) { | |
1160 | if (compat20) { | |
e9a17296 | 1161 | type = packet_read_poll2(seqnr_p); |
3c0ef626 | 1162 | if (type) |
1163 | DBG(debug("received packet type %d", type)); | |
e9a17296 | 1164 | switch (type) { |
3c0ef626 | 1165 | case SSH2_MSG_IGNORE: |
1166 | break; | |
1167 | case SSH2_MSG_DEBUG: | |
1168 | packet_get_char(); | |
1169 | msg = packet_get_string(NULL); | |
1170 | debug("Remote: %.900s", msg); | |
1171 | xfree(msg); | |
1172 | msg = packet_get_string(NULL); | |
1173 | xfree(msg); | |
1174 | break; | |
1175 | case SSH2_MSG_DISCONNECT: | |
1176 | reason = packet_get_int(); | |
1177 | msg = packet_get_string(NULL); | |
0fff78ff | 1178 | logit("Received disconnect from %s: %u: %.400s", |
680cee3b | 1179 | get_remote_ipaddr(), reason, msg); |
3c0ef626 | 1180 | xfree(msg); |
cdd66111 | 1181 | cleanup_exit(255); |
3c0ef626 | 1182 | break; |
e9a17296 | 1183 | case SSH2_MSG_UNIMPLEMENTED: |
1184 | seqnr = packet_get_int(); | |
680cee3b | 1185 | debug("Received SSH2_MSG_UNIMPLEMENTED for %u", |
1186 | seqnr); | |
e9a17296 | 1187 | break; |
3c0ef626 | 1188 | default: |
1189 | return type; | |
1190 | break; | |
1191 | } | |
1192 | } else { | |
e9a17296 | 1193 | type = packet_read_poll1(); |
1194 | switch (type) { | |
3c0ef626 | 1195 | case SSH_MSG_IGNORE: |
1196 | break; | |
1197 | case SSH_MSG_DEBUG: | |
1198 | msg = packet_get_string(NULL); | |
1199 | debug("Remote: %.900s", msg); | |
1200 | xfree(msg); | |
1201 | break; | |
1202 | case SSH_MSG_DISCONNECT: | |
1203 | msg = packet_get_string(NULL); | |
0fff78ff | 1204 | logit("Received disconnect from %s: %.400s", |
680cee3b | 1205 | get_remote_ipaddr(), msg); |
cdd66111 | 1206 | cleanup_exit(255); |
3c0ef626 | 1207 | xfree(msg); |
1208 | break; | |
1209 | default: | |
1210 | if (type) | |
1211 | DBG(debug("received packet type %d", type)); | |
1212 | return type; | |
1213 | break; | |
1214 | } | |
1215 | } | |
1216 | } | |
1217 | } | |
1218 | ||
e9a17296 | 1219 | int |
1220 | packet_read_poll(void) | |
1221 | { | |
1222 | return packet_read_poll_seqnr(NULL); | |
1223 | } | |
1224 | ||
3c0ef626 | 1225 | /* |
1226 | * Buffers the given amount of input characters. This is intended to be used | |
1227 | * together with packet_read_poll. | |
1228 | */ | |
1229 | ||
1230 | void | |
1231 | packet_process_incoming(const char *buf, u_int len) | |
1232 | { | |
1233 | buffer_append(&input, buf, len); | |
1234 | } | |
1235 | ||
1236 | /* Returns a character from the packet. */ | |
1237 | ||
1238 | u_int | |
e9a17296 | 1239 | packet_get_char(void) |
3c0ef626 | 1240 | { |
1241 | char ch; | |
41b2f314 | 1242 | |
3c0ef626 | 1243 | buffer_get(&incoming_packet, &ch, 1); |
1244 | return (u_char) ch; | |
1245 | } | |
1246 | ||
1247 | /* Returns an integer from the packet data. */ | |
1248 | ||
1249 | u_int | |
e9a17296 | 1250 | packet_get_int(void) |
3c0ef626 | 1251 | { |
1252 | return buffer_get_int(&incoming_packet); | |
1253 | } | |
1254 | ||
1255 | /* | |
1256 | * Returns an arbitrary precision integer from the packet data. The integer | |
1257 | * must have been initialized before this call. | |
1258 | */ | |
1259 | ||
1260 | void | |
e9a17296 | 1261 | packet_get_bignum(BIGNUM * value) |
3c0ef626 | 1262 | { |
e9a17296 | 1263 | buffer_get_bignum(&incoming_packet, value); |
3c0ef626 | 1264 | } |
1265 | ||
1266 | void | |
e9a17296 | 1267 | packet_get_bignum2(BIGNUM * value) |
3c0ef626 | 1268 | { |
e9a17296 | 1269 | buffer_get_bignum2(&incoming_packet, value); |
3c0ef626 | 1270 | } |
1271 | ||
e9a17296 | 1272 | void * |
665a873d | 1273 | packet_get_raw(u_int *length_ptr) |
3c0ef626 | 1274 | { |
665a873d | 1275 | u_int bytes = buffer_len(&incoming_packet); |
41b2f314 | 1276 | |
3c0ef626 | 1277 | if (length_ptr != NULL) |
1278 | *length_ptr = bytes; | |
1279 | return buffer_ptr(&incoming_packet); | |
1280 | } | |
1281 | ||
1282 | int | |
1283 | packet_remaining(void) | |
1284 | { | |
1285 | return buffer_len(&incoming_packet); | |
1286 | } | |
1287 | ||
1288 | /* | |
1289 | * Returns a string from the packet data. The string is allocated using | |
1290 | * xmalloc; it is the responsibility of the calling program to free it when | |
1291 | * no longer needed. The length_ptr argument may be NULL, or point to an | |
1292 | * integer into which the length of the string is stored. | |
1293 | */ | |
1294 | ||
e9a17296 | 1295 | void * |
3c0ef626 | 1296 | packet_get_string(u_int *length_ptr) |
1297 | { | |
1298 | return buffer_get_string(&incoming_packet, length_ptr); | |
1299 | } | |
1300 | ||
1301 | /* | |
1302 | * Sends a diagnostic message from the server to the client. This message | |
1303 | * can be sent at any time (but not while constructing another message). The | |
1304 | * message is printed immediately, but only if the client is being executed | |
1305 | * in verbose mode. These messages are primarily intended to ease debugging | |
1306 | * authentication problems. The length of the formatted message must not | |
1307 | * exceed 1024 bytes. This will automatically call packet_write_wait. | |
1308 | */ | |
1309 | ||
1310 | void | |
1311 | packet_send_debug(const char *fmt,...) | |
1312 | { | |
1313 | char buf[1024]; | |
1314 | va_list args; | |
1315 | ||
1316 | if (compat20 && (datafellows & SSH_BUG_DEBUG)) | |
1317 | return; | |
1318 | ||
1319 | va_start(args, fmt); | |
1320 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1321 | va_end(args); | |
1322 | ||
1323 | if (compat20) { | |
1324 | packet_start(SSH2_MSG_DEBUG); | |
1325 | packet_put_char(0); /* bool: always display */ | |
1326 | packet_put_cstring(buf); | |
1327 | packet_put_cstring(""); | |
1328 | } else { | |
1329 | packet_start(SSH_MSG_DEBUG); | |
1330 | packet_put_cstring(buf); | |
1331 | } | |
1332 | packet_send(); | |
1333 | packet_write_wait(); | |
1334 | } | |
1335 | ||
1336 | /* | |
1337 | * Logs the error plus constructs and sends a disconnect packet, closes the | |
1338 | * connection, and exits. This function never returns. The error message | |
1339 | * should not contain a newline. The length of the formatted message must | |
1340 | * not exceed 1024 bytes. | |
1341 | */ | |
1342 | ||
1343 | void | |
1344 | packet_disconnect(const char *fmt,...) | |
1345 | { | |
1346 | char buf[1024]; | |
1347 | va_list args; | |
1348 | static int disconnecting = 0; | |
41b2f314 | 1349 | |
3c0ef626 | 1350 | if (disconnecting) /* Guard against recursive invocations. */ |
1351 | fatal("packet_disconnect called recursively."); | |
1352 | disconnecting = 1; | |
1353 | ||
1354 | /* | |
1355 | * Format the message. Note that the caller must make sure the | |
1356 | * message is of limited size. | |
1357 | */ | |
1358 | va_start(args, fmt); | |
1359 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1360 | va_end(args); | |
1361 | ||
6a9b3198 | 1362 | /* Display the error locally */ |
0fff78ff | 1363 | logit("Disconnecting: %.100s", buf); |
6a9b3198 | 1364 | |
3c0ef626 | 1365 | /* Send the disconnect message to the other side, and wait for it to get sent. */ |
1366 | if (compat20) { | |
1367 | packet_start(SSH2_MSG_DISCONNECT); | |
1368 | packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); | |
1369 | packet_put_cstring(buf); | |
1370 | packet_put_cstring(""); | |
1371 | } else { | |
1372 | packet_start(SSH_MSG_DISCONNECT); | |
1373 | packet_put_cstring(buf); | |
1374 | } | |
1375 | packet_send(); | |
1376 | packet_write_wait(); | |
1377 | ||
1378 | /* Stop listening for connections. */ | |
1379 | channel_close_all(); | |
1380 | ||
1381 | /* Close the connection. */ | |
1382 | packet_close(); | |
cdd66111 | 1383 | cleanup_exit(255); |
3c0ef626 | 1384 | } |
1385 | ||
1386 | /* Checks if there is any buffered output, and tries to write some of the output. */ | |
1387 | ||
1388 | void | |
e9a17296 | 1389 | packet_write_poll(void) |
3c0ef626 | 1390 | { |
1391 | int len = buffer_len(&output); | |
41b2f314 | 1392 | |
3c0ef626 | 1393 | if (len > 0) { |
1394 | len = write(connection_out, buffer_ptr(&output), len); | |
1395 | if (len <= 0) { | |
1396 | if (errno == EAGAIN) | |
1397 | return; | |
1398 | else | |
1399 | fatal("Write failed: %.100s", strerror(errno)); | |
1400 | } | |
1401 | buffer_consume(&output, len); | |
1402 | } | |
1403 | } | |
1404 | ||
1405 | /* | |
1406 | * Calls packet_write_poll repeatedly until all pending output data has been | |
1407 | * written. | |
1408 | */ | |
1409 | ||
1410 | void | |
e9a17296 | 1411 | packet_write_wait(void) |
3c0ef626 | 1412 | { |
1413 | fd_set *setp; | |
1414 | ||
1415 | setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * | |
1416 | sizeof(fd_mask)); | |
1417 | packet_write_poll(); | |
1418 | while (packet_have_data_to_write()) { | |
1419 | memset(setp, 0, howmany(connection_out + 1, NFDBITS) * | |
1420 | sizeof(fd_mask)); | |
1421 | FD_SET(connection_out, setp); | |
1422 | while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && | |
1423 | (errno == EAGAIN || errno == EINTR)) | |
1424 | ; | |
1425 | packet_write_poll(); | |
1426 | } | |
1427 | xfree(setp); | |
1428 | } | |
1429 | ||
1430 | /* Returns true if there is buffered data to write to the connection. */ | |
1431 | ||
1432 | int | |
e9a17296 | 1433 | packet_have_data_to_write(void) |
3c0ef626 | 1434 | { |
1435 | return buffer_len(&output) != 0; | |
1436 | } | |
1437 | ||
1438 | /* Returns true if there is not too much data to write to the connection. */ | |
1439 | ||
1440 | int | |
e9a17296 | 1441 | packet_not_very_much_data_to_write(void) |
3c0ef626 | 1442 | { |
1443 | if (interactive_mode) | |
1444 | return buffer_len(&output) < 16384; | |
1445 | else | |
1446 | return buffer_len(&output) < 128 * 1024; | |
1447 | } | |
1448 | ||
0fff78ff | 1449 | |
6a9b3198 | 1450 | static void |
1451 | packet_set_tos(int interactive) | |
1452 | { | |
cdd66111 | 1453 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) |
6a9b3198 | 1454 | int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; |
1455 | ||
1456 | if (!packet_connection_is_on_socket() || | |
1457 | !packet_connection_is_ipv4()) | |
1458 | return; | |
1459 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, | |
1460 | sizeof(tos)) < 0) | |
1461 | error("setsockopt IP_TOS %d: %.100s:", | |
1462 | tos, strerror(errno)); | |
9cb1827b | 1463 | #endif |
cdd66111 | 1464 | } |
6a9b3198 | 1465 | |
3c0ef626 | 1466 | /* Informs that the current session is interactive. Sets IP flags for that. */ |
1467 | ||
1468 | void | |
1469 | packet_set_interactive(int interactive) | |
1470 | { | |
1471 | static int called = 0; | |
3c0ef626 | 1472 | |
1473 | if (called) | |
1474 | return; | |
1475 | called = 1; | |
1476 | ||
1477 | /* Record that we are in interactive mode. */ | |
1478 | interactive_mode = interactive; | |
1479 | ||
1480 | /* Only set socket options if using a socket. */ | |
1481 | if (!packet_connection_is_on_socket()) | |
0fff78ff | 1482 | return; |
6a9b3198 | 1483 | if (interactive) |
e9a17296 | 1484 | set_nodelay(connection_in); |
6a9b3198 | 1485 | packet_set_tos(interactive); |
3c0ef626 | 1486 | } |
1487 | ||
1488 | /* Returns true if the current connection is interactive. */ | |
1489 | ||
1490 | int | |
e9a17296 | 1491 | packet_is_interactive(void) |
3c0ef626 | 1492 | { |
1493 | return interactive_mode; | |
1494 | } | |
1495 | ||
c9f39d2c | 1496 | int |
0fff78ff | 1497 | packet_set_maxsize(u_int s) |
3c0ef626 | 1498 | { |
1499 | static int called = 0; | |
41b2f314 | 1500 | |
3c0ef626 | 1501 | if (called) { |
0fff78ff | 1502 | logit("packet_set_maxsize: called twice: old %d new %d", |
3c0ef626 | 1503 | max_packet_size, s); |
1504 | return -1; | |
1505 | } | |
1506 | if (s < 4 * 1024 || s > 1024 * 1024) { | |
0fff78ff | 1507 | logit("packet_set_maxsize: bad size %d", s); |
3c0ef626 | 1508 | return -1; |
1509 | } | |
1510 | called = 1; | |
1511 | debug("packet_set_maxsize: setting to %d", s); | |
1512 | max_packet_size = s; | |
1513 | return s; | |
1514 | } | |
1515 | ||
1516 | /* roundup current message to pad bytes */ | |
1517 | void | |
1518 | packet_add_padding(u_char pad) | |
1519 | { | |
1520 | extra_pad = pad; | |
1521 | } | |
1522 | ||
1523 | /* | |
1524 | * 9.2. Ignored Data Message | |
1525 | * | |
1526 | * byte SSH_MSG_IGNORE | |
1527 | * string data | |
1528 | * | |
1529 | * All implementations MUST understand (and ignore) this message at any | |
1530 | * time (after receiving the protocol version). No implementation is | |
1531 | * required to send them. This message can be used as an additional | |
1532 | * protection measure against advanced traffic analysis techniques. | |
1533 | */ | |
1534 | void | |
1535 | packet_send_ignore(int nbytes) | |
1536 | { | |
c9f39d2c | 1537 | u_int32_t rnd = 0; |
3c0ef626 | 1538 | int i; |
1539 | ||
1540 | packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); | |
1541 | packet_put_int(nbytes); | |
e9a17296 | 1542 | for (i = 0; i < nbytes; i++) { |
3c0ef626 | 1543 | if (i % 4 == 0) |
c9f39d2c | 1544 | rnd = arc4random(); |
1545 | packet_put_char(rnd & 0xff); | |
1546 | rnd >>= 8; | |
3c0ef626 | 1547 | } |
1548 | } | |
0fff78ff | 1549 | |
c9f39d2c | 1550 | #define MAX_PACKETS (1U<<31) |
0fff78ff | 1551 | int |
1552 | packet_need_rekeying(void) | |
1553 | { | |
1554 | if (datafellows & SSH_BUG_NOREKEY) | |
1555 | return 0; | |
1556 | return | |
1557 | (p_send.packets > MAX_PACKETS) || | |
1558 | (p_read.packets > MAX_PACKETS) || | |
1559 | (max_blocks_out && (p_send.blocks > max_blocks_out)) || | |
1560 | (max_blocks_in && (p_read.blocks > max_blocks_in)); | |
1561 | } | |
1562 | ||
1563 | void | |
1564 | packet_set_rekey_limit(u_int32_t bytes) | |
1565 | { | |
1566 | rekey_limit = bytes; | |
1567 | } | |
665a873d | 1568 | |
1569 | void | |
1570 | packet_set_server(void) | |
1571 | { | |
1572 | server_side = 1; | |
1573 | } | |
1574 | ||
1575 | void | |
1576 | packet_set_authenticated(void) | |
1577 | { | |
1578 | after_authentication = 1; | |
1579 | } |