]>
Commit | Line | Data |
---|---|---|
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" | |
40 | RCSID("$OpenBSD: packet.c,v 1.112 2003/09/23 20:17:11 markus Exp $"); | |
41 | ||
42 | #include "openbsd-compat/sys-queue.h" | |
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" | |
64 | #include "misc.h" | |
65 | #include "ssh.h" | |
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. */ | |
92 | Buffer input; | |
93 | ||
94 | /* Buffer for raw output data going to the socket. */ | |
95 | Buffer output; | |
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 */ | |
111 | u_int max_packet_size = 32768; | |
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 | ||
119 | /* Session key information for Encryption and MAC */ | |
120 | Newkeys *newkeys[MODE_MAX]; | |
121 | static struct packet_state { | |
122 | u_int32_t seqnr; | |
123 | u_int32_t packets; | |
124 | u_int64_t blocks; | |
125 | } p_read, p_send; | |
126 | ||
127 | static u_int64_t max_blocks_in, max_blocks_out; | |
128 | static u_int32_t rekey_limit; | |
129 | ||
130 | /* Session key for protocol v1 */ | |
131 | static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; | |
132 | static u_int ssh1_keylen; | |
133 | ||
134 | /* roundup current message to extra_pad bytes */ | |
135 | static u_char extra_pad = 0; | |
136 | ||
137 | struct packet { | |
138 | TAILQ_ENTRY(packet) next; | |
139 | u_char type; | |
140 | Buffer payload; | |
141 | }; | |
142 | TAILQ_HEAD(, packet) outgoing; | |
143 | ||
144 | /* | |
145 | * Sets the descriptors used for communication. Disables encryption until | |
146 | * packet_set_encryption_key is called. | |
147 | */ | |
148 | void | |
149 | packet_set_connection(int fd_in, int fd_out) | |
150 | { | |
151 | Cipher *none = cipher_by_name("none"); | |
152 | ||
153 | if (none == NULL) | |
154 | fatal("packet_set_connection: cannot load cipher 'none'"); | |
155 | connection_in = fd_in; | |
156 | connection_out = fd_out; | |
157 | cipher_init(&send_context, none, "", 0, NULL, 0, CIPHER_ENCRYPT); | |
158 | cipher_init(&receive_context, none, "", 0, NULL, 0, CIPHER_DECRYPT); | |
159 | newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; | |
160 | if (!initialized) { | |
161 | initialized = 1; | |
162 | buffer_init(&input); | |
163 | buffer_init(&output); | |
164 | buffer_init(&outgoing_packet); | |
165 | buffer_init(&incoming_packet); | |
166 | TAILQ_INIT(&outgoing); | |
167 | } | |
168 | } | |
169 | ||
170 | /* Returns 1 if remote host is connected via socket, 0 if not. */ | |
171 | ||
172 | int | |
173 | packet_connection_is_on_socket(void) | |
174 | { | |
175 | struct sockaddr_storage from, to; | |
176 | socklen_t fromlen, tolen; | |
177 | ||
178 | /* filedescriptors in and out are the same, so it's a socket */ | |
179 | if (connection_in == connection_out) | |
180 | return 1; | |
181 | fromlen = sizeof(from); | |
182 | memset(&from, 0, sizeof(from)); | |
183 | if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) | |
184 | return 0; | |
185 | tolen = sizeof(to); | |
186 | memset(&to, 0, sizeof(to)); | |
187 | if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
188 | return 0; | |
189 | if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) | |
190 | return 0; | |
191 | if (from.ss_family != AF_INET && from.ss_family != AF_INET6) | |
192 | return 0; | |
193 | return 1; | |
194 | } | |
195 | ||
196 | /* | |
197 | * Exports an IV from the CipherContext required to export the key | |
198 | * state back from the unprivileged child to the privileged parent | |
199 | * process. | |
200 | */ | |
201 | ||
202 | void | |
203 | packet_get_keyiv(int mode, u_char *iv, u_int len) | |
204 | { | |
205 | CipherContext *cc; | |
206 | ||
207 | if (mode == MODE_OUT) | |
208 | cc = &send_context; | |
209 | else | |
210 | cc = &receive_context; | |
211 | ||
212 | cipher_get_keyiv(cc, iv, len); | |
213 | } | |
214 | ||
215 | int | |
216 | packet_get_keycontext(int mode, u_char *dat) | |
217 | { | |
218 | CipherContext *cc; | |
219 | ||
220 | if (mode == MODE_OUT) | |
221 | cc = &send_context; | |
222 | else | |
223 | cc = &receive_context; | |
224 | ||
225 | return (cipher_get_keycontext(cc, dat)); | |
226 | } | |
227 | ||
228 | void | |
229 | packet_set_keycontext(int mode, u_char *dat) | |
230 | { | |
231 | CipherContext *cc; | |
232 | ||
233 | if (mode == MODE_OUT) | |
234 | cc = &send_context; | |
235 | else | |
236 | cc = &receive_context; | |
237 | ||
238 | cipher_set_keycontext(cc, dat); | |
239 | } | |
240 | ||
241 | int | |
242 | packet_get_keyiv_len(int mode) | |
243 | { | |
244 | CipherContext *cc; | |
245 | ||
246 | if (mode == MODE_OUT) | |
247 | cc = &send_context; | |
248 | else | |
249 | cc = &receive_context; | |
250 | ||
251 | return (cipher_get_keyiv_len(cc)); | |
252 | } | |
253 | void | |
254 | packet_set_iv(int mode, u_char *dat) | |
255 | { | |
256 | CipherContext *cc; | |
257 | ||
258 | if (mode == MODE_OUT) | |
259 | cc = &send_context; | |
260 | else | |
261 | cc = &receive_context; | |
262 | ||
263 | cipher_set_keyiv(cc, dat); | |
264 | } | |
265 | int | |
266 | packet_get_ssh1_cipher(void) | |
267 | { | |
268 | return (cipher_get_number(receive_context.cipher)); | |
269 | } | |
270 | ||
271 | void | |
272 | packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets) | |
273 | { | |
274 | struct packet_state *state; | |
275 | ||
276 | state = (mode == MODE_IN) ? &p_read : &p_send; | |
277 | *seqnr = state->seqnr; | |
278 | *blocks = state->blocks; | |
279 | *packets = state->packets; | |
280 | } | |
281 | ||
282 | void | |
283 | packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets) | |
284 | { | |
285 | struct packet_state *state; | |
286 | ||
287 | state = (mode == MODE_IN) ? &p_read : &p_send; | |
288 | state->seqnr = seqnr; | |
289 | state->blocks = blocks; | |
290 | state->packets = packets; | |
291 | } | |
292 | ||
293 | /* returns 1 if connection is via ipv4 */ | |
294 | ||
295 | int | |
296 | packet_connection_is_ipv4(void) | |
297 | { | |
298 | struct sockaddr_storage to; | |
299 | socklen_t tolen = sizeof(to); | |
300 | ||
301 | memset(&to, 0, sizeof(to)); | |
302 | if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
303 | return 0; | |
304 | if (to.ss_family == AF_INET) | |
305 | return 1; | |
306 | #ifdef IPV4_IN_IPV6 | |
307 | if (to.ss_family == AF_INET6 && | |
308 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) | |
309 | return 1; | |
310 | #endif | |
311 | return 0; | |
312 | } | |
313 | ||
314 | /* Sets the connection into non-blocking mode. */ | |
315 | ||
316 | void | |
317 | packet_set_nonblocking(void) | |
318 | { | |
319 | /* Set the socket into non-blocking mode. */ | |
320 | if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) | |
321 | error("fcntl O_NONBLOCK: %.100s", strerror(errno)); | |
322 | ||
323 | if (connection_out != connection_in) { | |
324 | if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0) | |
325 | error("fcntl O_NONBLOCK: %.100s", strerror(errno)); | |
326 | } | |
327 | } | |
328 | ||
329 | /* Returns the socket used for reading. */ | |
330 | ||
331 | int | |
332 | packet_get_connection_in(void) | |
333 | { | |
334 | return connection_in; | |
335 | } | |
336 | ||
337 | /* Returns the descriptor used for writing. */ | |
338 | ||
339 | int | |
340 | packet_get_connection_out(void) | |
341 | { | |
342 | return connection_out; | |
343 | } | |
344 | ||
345 | /* Closes the connection and clears and frees internal data structures. */ | |
346 | ||
347 | void | |
348 | packet_close(void) | |
349 | { | |
350 | if (!initialized) | |
351 | return; | |
352 | initialized = 0; | |
353 | if (connection_in == connection_out) { | |
354 | shutdown(connection_out, SHUT_RDWR); | |
355 | close(connection_out); | |
356 | } else { | |
357 | close(connection_in); | |
358 | close(connection_out); | |
359 | } | |
360 | buffer_free(&input); | |
361 | buffer_free(&output); | |
362 | buffer_free(&outgoing_packet); | |
363 | buffer_free(&incoming_packet); | |
364 | if (compression_buffer_ready) { | |
365 | buffer_free(&compression_buffer); | |
366 | buffer_compress_uninit(); | |
367 | } | |
368 | cipher_cleanup(&send_context); | |
369 | cipher_cleanup(&receive_context); | |
370 | } | |
371 | ||
372 | /* Sets remote side protocol flags. */ | |
373 | ||
374 | void | |
375 | packet_set_protocol_flags(u_int protocol_flags) | |
376 | { | |
377 | remote_protocol_flags = protocol_flags; | |
378 | } | |
379 | ||
380 | /* Returns the remote protocol flags set earlier by the above function. */ | |
381 | ||
382 | u_int | |
383 | packet_get_protocol_flags(void) | |
384 | { | |
385 | return remote_protocol_flags; | |
386 | } | |
387 | ||
388 | /* | |
389 | * Starts packet compression from the next packet on in both directions. | |
390 | * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. | |
391 | */ | |
392 | ||
393 | static void | |
394 | packet_init_compression(void) | |
395 | { | |
396 | if (compression_buffer_ready == 1) | |
397 | return; | |
398 | compression_buffer_ready = 1; | |
399 | buffer_init(&compression_buffer); | |
400 | } | |
401 | ||
402 | void | |
403 | packet_start_compression(int level) | |
404 | { | |
405 | if (packet_compression && !compat20) | |
406 | fatal("Compression already enabled."); | |
407 | packet_compression = 1; | |
408 | packet_init_compression(); | |
409 | buffer_compress_init_send(level); | |
410 | buffer_compress_init_recv(); | |
411 | } | |
412 | ||
413 | /* | |
414 | * Causes any further packets to be encrypted using the given key. The same | |
415 | * key is used for both sending and reception. However, both directions are | |
416 | * encrypted independently of each other. | |
417 | */ | |
418 | ||
419 | void | |
420 | packet_set_encryption_key(const u_char *key, u_int keylen, | |
421 | int number) | |
422 | { | |
423 | Cipher *cipher = cipher_by_number(number); | |
424 | ||
425 | if (cipher == NULL) | |
426 | fatal("packet_set_encryption_key: unknown cipher number %d", number); | |
427 | if (keylen < 20) | |
428 | fatal("packet_set_encryption_key: keylen too small: %d", keylen); | |
429 | if (keylen > SSH_SESSION_KEY_LENGTH) | |
430 | fatal("packet_set_encryption_key: keylen too big: %d", keylen); | |
431 | memcpy(ssh1_key, key, keylen); | |
432 | ssh1_keylen = keylen; | |
433 | cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); | |
434 | cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); | |
435 | } | |
436 | ||
437 | u_int | |
438 | packet_get_encryption_key(u_char *key) | |
439 | { | |
440 | if (key == NULL) | |
441 | return (ssh1_keylen); | |
442 | memcpy(key, ssh1_key, ssh1_keylen); | |
443 | return (ssh1_keylen); | |
444 | } | |
445 | ||
446 | /* Start constructing a packet to send. */ | |
447 | void | |
448 | packet_start(u_char type) | |
449 | { | |
450 | u_char buf[9]; | |
451 | int len; | |
452 | ||
453 | DBG(debug("packet_start[%d]", type)); | |
454 | len = compat20 ? 6 : 9; | |
455 | memset(buf, 0, len - 1); | |
456 | buf[len - 1] = type; | |
457 | buffer_clear(&outgoing_packet); | |
458 | buffer_append(&outgoing_packet, buf, len); | |
459 | } | |
460 | ||
461 | /* Append payload. */ | |
462 | void | |
463 | packet_put_char(int value) | |
464 | { | |
465 | char ch = value; | |
466 | ||
467 | buffer_append(&outgoing_packet, &ch, 1); | |
468 | } | |
469 | void | |
470 | packet_put_int(u_int value) | |
471 | { | |
472 | buffer_put_int(&outgoing_packet, value); | |
473 | } | |
474 | void | |
475 | packet_put_string(const void *buf, u_int len) | |
476 | { | |
477 | buffer_put_string(&outgoing_packet, buf, len); | |
478 | } | |
479 | void | |
480 | packet_put_cstring(const char *str) | |
481 | { | |
482 | buffer_put_cstring(&outgoing_packet, str); | |
483 | } | |
484 | void | |
485 | packet_put_raw(const void *buf, u_int len) | |
486 | { | |
487 | buffer_append(&outgoing_packet, buf, len); | |
488 | } | |
489 | void | |
490 | packet_put_bignum(BIGNUM * value) | |
491 | { | |
492 | buffer_put_bignum(&outgoing_packet, value); | |
493 | } | |
494 | void | |
495 | packet_put_bignum2(BIGNUM * value) | |
496 | { | |
497 | buffer_put_bignum2(&outgoing_packet, value); | |
498 | } | |
499 | ||
500 | /* | |
501 | * Finalizes and sends the packet. If the encryption key has been set, | |
502 | * encrypts the packet before sending. | |
503 | */ | |
504 | ||
505 | static void | |
506 | packet_send1(void) | |
507 | { | |
508 | u_char buf[8], *cp; | |
509 | int i, padding, len; | |
510 | u_int checksum; | |
511 | u_int32_t rand = 0; | |
512 | ||
513 | /* | |
514 | * If using packet compression, compress the payload of the outgoing | |
515 | * packet. | |
516 | */ | |
517 | if (packet_compression) { | |
518 | buffer_clear(&compression_buffer); | |
519 | /* Skip padding. */ | |
520 | buffer_consume(&outgoing_packet, 8); | |
521 | /* padding */ | |
522 | buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); | |
523 | buffer_compress(&outgoing_packet, &compression_buffer); | |
524 | buffer_clear(&outgoing_packet); | |
525 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
526 | buffer_len(&compression_buffer)); | |
527 | } | |
528 | /* Compute packet length without padding (add checksum, remove padding). */ | |
529 | len = buffer_len(&outgoing_packet) + 4 - 8; | |
530 | ||
531 | /* Insert padding. Initialized to zero in packet_start1() */ | |
532 | padding = 8 - len % 8; | |
533 | if (!send_context.plaintext) { | |
534 | cp = buffer_ptr(&outgoing_packet); | |
535 | for (i = 0; i < padding; i++) { | |
536 | if (i % 4 == 0) | |
537 | rand = arc4random(); | |
538 | cp[7 - i] = rand & 0xff; | |
539 | rand >>= 8; | |
540 | } | |
541 | } | |
542 | buffer_consume(&outgoing_packet, 8 - padding); | |
543 | ||
544 | /* Add check bytes. */ | |
545 | checksum = ssh_crc32(buffer_ptr(&outgoing_packet), | |
546 | buffer_len(&outgoing_packet)); | |
547 | PUT_32BIT(buf, checksum); | |
548 | buffer_append(&outgoing_packet, buf, 4); | |
549 | ||
550 | #ifdef PACKET_DEBUG | |
551 | fprintf(stderr, "packet_send plain: "); | |
552 | buffer_dump(&outgoing_packet); | |
553 | #endif | |
554 | ||
555 | /* Append to output. */ | |
556 | PUT_32BIT(buf, len); | |
557 | buffer_append(&output, buf, 4); | |
558 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); | |
559 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
560 | buffer_len(&outgoing_packet)); | |
561 | ||
562 | #ifdef PACKET_DEBUG | |
563 | fprintf(stderr, "encrypted: "); | |
564 | buffer_dump(&output); | |
565 | #endif | |
566 | ||
567 | buffer_clear(&outgoing_packet); | |
568 | ||
569 | /* | |
570 | * Note that the packet is now only buffered in output. It won\'t be | |
571 | * actually sent until packet_write_wait or packet_write_poll is | |
572 | * called. | |
573 | */ | |
574 | } | |
575 | ||
576 | void | |
577 | set_newkeys(int mode) | |
578 | { | |
579 | Enc *enc; | |
580 | Mac *mac; | |
581 | Comp *comp; | |
582 | CipherContext *cc; | |
583 | u_int64_t *max_blocks; | |
584 | int encrypt; | |
585 | ||
586 | debug2("set_newkeys: mode %d", mode); | |
587 | ||
588 | if (mode == MODE_OUT) { | |
589 | cc = &send_context; | |
590 | encrypt = CIPHER_ENCRYPT; | |
591 | p_send.packets = p_send.blocks = 0; | |
592 | max_blocks = &max_blocks_out; | |
593 | } else { | |
594 | cc = &receive_context; | |
595 | encrypt = CIPHER_DECRYPT; | |
596 | p_read.packets = p_read.blocks = 0; | |
597 | max_blocks = &max_blocks_in; | |
598 | } | |
599 | if (newkeys[mode] != NULL) { | |
600 | debug("set_newkeys: rekeying"); | |
601 | cipher_cleanup(cc); | |
602 | enc = &newkeys[mode]->enc; | |
603 | mac = &newkeys[mode]->mac; | |
604 | comp = &newkeys[mode]->comp; | |
605 | memset(mac->key, 0, mac->key_len); | |
606 | xfree(enc->name); | |
607 | xfree(enc->iv); | |
608 | xfree(enc->key); | |
609 | xfree(mac->name); | |
610 | xfree(mac->key); | |
611 | xfree(comp->name); | |
612 | xfree(newkeys[mode]); | |
613 | } | |
614 | newkeys[mode] = kex_get_newkeys(mode); | |
615 | if (newkeys[mode] == NULL) | |
616 | fatal("newkeys: no keys for mode %d", mode); | |
617 | enc = &newkeys[mode]->enc; | |
618 | mac = &newkeys[mode]->mac; | |
619 | comp = &newkeys[mode]->comp; | |
620 | if (mac->md != NULL) | |
621 | mac->enabled = 1; | |
622 | DBG(debug("cipher_init_context: %d", mode)); | |
623 | cipher_init(cc, enc->cipher, enc->key, enc->key_len, | |
624 | enc->iv, enc->block_size, encrypt); | |
625 | /* Deleting the keys does not gain extra security */ | |
626 | /* memset(enc->iv, 0, enc->block_size); | |
627 | memset(enc->key, 0, enc->key_len); */ | |
628 | if (comp->type != 0 && comp->enabled == 0) { | |
629 | packet_init_compression(); | |
630 | if (mode == MODE_OUT) | |
631 | buffer_compress_init_send(6); | |
632 | else | |
633 | buffer_compress_init_recv(); | |
634 | comp->enabled = 1; | |
635 | } | |
636 | /* | |
637 | * The 2^(blocksize*2) limit is too expensive for 3DES, | |
638 | * blowfish, etc, so enforce a 1GB limit for small blocksizes. | |
639 | */ | |
640 | if (enc->block_size >= 16) | |
641 | *max_blocks = (u_int64_t)1 << (enc->block_size*2); | |
642 | else | |
643 | *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; | |
644 | if (rekey_limit) | |
645 | *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); | |
646 | } | |
647 | ||
648 | /* | |
649 | * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) | |
650 | */ | |
651 | static void | |
652 | packet_send2_wrapped(void) | |
653 | { | |
654 | u_char type, *cp, *macbuf = NULL; | |
655 | u_char padlen, pad; | |
656 | u_int packet_length = 0; | |
657 | u_int i, len; | |
658 | u_int32_t rand = 0; | |
659 | Enc *enc = NULL; | |
660 | Mac *mac = NULL; | |
661 | Comp *comp = NULL; | |
662 | int block_size; | |
663 | ||
664 | if (newkeys[MODE_OUT] != NULL) { | |
665 | enc = &newkeys[MODE_OUT]->enc; | |
666 | mac = &newkeys[MODE_OUT]->mac; | |
667 | comp = &newkeys[MODE_OUT]->comp; | |
668 | } | |
669 | block_size = enc ? enc->block_size : 8; | |
670 | ||
671 | cp = buffer_ptr(&outgoing_packet); | |
672 | type = cp[5]; | |
673 | ||
674 | #ifdef PACKET_DEBUG | |
675 | fprintf(stderr, "plain: "); | |
676 | buffer_dump(&outgoing_packet); | |
677 | #endif | |
678 | ||
679 | if (comp && comp->enabled) { | |
680 | len = buffer_len(&outgoing_packet); | |
681 | /* skip header, compress only payload */ | |
682 | buffer_consume(&outgoing_packet, 5); | |
683 | buffer_clear(&compression_buffer); | |
684 | buffer_compress(&outgoing_packet, &compression_buffer); | |
685 | buffer_clear(&outgoing_packet); | |
686 | buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); | |
687 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
688 | buffer_len(&compression_buffer)); | |
689 | DBG(debug("compression: raw %d compressed %d", len, | |
690 | buffer_len(&outgoing_packet))); | |
691 | } | |
692 | ||
693 | /* sizeof (packet_len + pad_len + payload) */ | |
694 | len = buffer_len(&outgoing_packet); | |
695 | ||
696 | /* | |
697 | * calc size of padding, alloc space, get random data, | |
698 | * minimum padding is 4 bytes | |
699 | */ | |
700 | padlen = block_size - (len % block_size); | |
701 | if (padlen < 4) | |
702 | padlen += block_size; | |
703 | if (extra_pad) { | |
704 | /* will wrap if extra_pad+padlen > 255 */ | |
705 | extra_pad = roundup(extra_pad, block_size); | |
706 | pad = extra_pad - ((len + padlen) % extra_pad); | |
707 | debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", | |
708 | pad, len, padlen, extra_pad); | |
709 | padlen += pad; | |
710 | extra_pad = 0; | |
711 | } | |
712 | cp = buffer_append_space(&outgoing_packet, padlen); | |
713 | if (enc && !send_context.plaintext) { | |
714 | /* random padding */ | |
715 | for (i = 0; i < padlen; i++) { | |
716 | if (i % 4 == 0) | |
717 | rand = arc4random(); | |
718 | cp[i] = rand & 0xff; | |
719 | rand >>= 8; | |
720 | } | |
721 | } else { | |
722 | /* clear padding */ | |
723 | memset(cp, 0, padlen); | |
724 | } | |
725 | /* packet_length includes payload, padding and padding length field */ | |
726 | packet_length = buffer_len(&outgoing_packet) - 4; | |
727 | cp = buffer_ptr(&outgoing_packet); | |
728 | PUT_32BIT(cp, packet_length); | |
729 | cp[4] = padlen; | |
730 | DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); | |
731 | ||
732 | /* compute MAC over seqnr and packet(length fields, payload, padding) */ | |
733 | if (mac && mac->enabled) { | |
734 | macbuf = mac_compute(mac, p_send.seqnr, | |
735 | buffer_ptr(&outgoing_packet), | |
736 | buffer_len(&outgoing_packet)); | |
737 | DBG(debug("done calc MAC out #%d", p_send.seqnr)); | |
738 | } | |
739 | /* encrypt packet and append to output buffer. */ | |
740 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); | |
741 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
742 | buffer_len(&outgoing_packet)); | |
743 | /* append unencrypted MAC */ | |
744 | if (mac && mac->enabled) | |
745 | buffer_append(&output, (char *)macbuf, mac->mac_len); | |
746 | #ifdef PACKET_DEBUG | |
747 | fprintf(stderr, "encrypted: "); | |
748 | buffer_dump(&output); | |
749 | #endif | |
750 | /* increment sequence number for outgoing packets */ | |
751 | if (++p_send.seqnr == 0) | |
752 | logit("outgoing seqnr wraps around"); | |
753 | if (++p_send.packets == 0) | |
754 | if (!(datafellows & SSH_BUG_NOREKEY)) | |
755 | fatal("XXX too many packets with same key"); | |
756 | p_send.blocks += (packet_length + 4) / block_size; | |
757 | buffer_clear(&outgoing_packet); | |
758 | ||
759 | if (type == SSH2_MSG_NEWKEYS) | |
760 | set_newkeys(MODE_OUT); | |
761 | } | |
762 | ||
763 | static void | |
764 | packet_send2(void) | |
765 | { | |
766 | static int rekeying = 0; | |
767 | struct packet *p; | |
768 | u_char type, *cp; | |
769 | ||
770 | cp = buffer_ptr(&outgoing_packet); | |
771 | type = cp[5]; | |
772 | ||
773 | /* during rekeying we can only send key exchange messages */ | |
774 | if (rekeying) { | |
775 | if (!((type >= SSH2_MSG_TRANSPORT_MIN) && | |
776 | (type <= SSH2_MSG_TRANSPORT_MAX))) { | |
777 | debug("enqueue packet: %u", type); | |
778 | p = xmalloc(sizeof(*p)); | |
779 | p->type = type; | |
780 | memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); | |
781 | buffer_init(&outgoing_packet); | |
782 | TAILQ_INSERT_TAIL(&outgoing, p, next); | |
783 | return; | |
784 | } | |
785 | } | |
786 | ||
787 | /* rekeying starts with sending KEXINIT */ | |
788 | if (type == SSH2_MSG_KEXINIT) | |
789 | rekeying = 1; | |
790 | ||
791 | packet_send2_wrapped(); | |
792 | ||
793 | /* after a NEWKEYS message we can send the complete queue */ | |
794 | if (type == SSH2_MSG_NEWKEYS) { | |
795 | rekeying = 0; | |
796 | while ((p = TAILQ_FIRST(&outgoing))) { | |
797 | type = p->type; | |
798 | debug("dequeue packet: %u", type); | |
799 | buffer_free(&outgoing_packet); | |
800 | memcpy(&outgoing_packet, &p->payload, | |
801 | sizeof(Buffer)); | |
802 | TAILQ_REMOVE(&outgoing, p, next); | |
803 | xfree(p); | |
804 | packet_send2_wrapped(); | |
805 | } | |
806 | } | |
807 | } | |
808 | ||
809 | void | |
810 | packet_send(void) | |
811 | { | |
812 | if (compat20) | |
813 | packet_send2(); | |
814 | else | |
815 | packet_send1(); | |
816 | DBG(debug("packet_send done")); | |
817 | } | |
818 | ||
819 | /* | |
820 | * Waits until a packet has been received, and returns its type. Note that | |
821 | * no other data is processed until this returns, so this function should not | |
822 | * be used during the interactive session. | |
823 | */ | |
824 | ||
825 | int | |
826 | packet_read_seqnr(u_int32_t *seqnr_p) | |
827 | { | |
828 | int type, len; | |
829 | fd_set *setp; | |
830 | char buf[8192]; | |
831 | DBG(debug("packet_read()")); | |
832 | ||
833 | setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * | |
834 | sizeof(fd_mask)); | |
835 | ||
836 | /* Since we are blocking, ensure that all written packets have been sent. */ | |
837 | packet_write_wait(); | |
838 | ||
839 | /* Stay in the loop until we have received a complete packet. */ | |
840 | for (;;) { | |
841 | /* Try to read a packet from the buffer. */ | |
842 | type = packet_read_poll_seqnr(seqnr_p); | |
843 | if (!compat20 && ( | |
844 | type == SSH_SMSG_SUCCESS | |
845 | || type == SSH_SMSG_FAILURE | |
846 | || type == SSH_CMSG_EOF | |
847 | || type == SSH_CMSG_EXIT_CONFIRMATION)) | |
848 | packet_check_eom(); | |
849 | /* If we got a packet, return it. */ | |
850 | if (type != SSH_MSG_NONE) { | |
851 | xfree(setp); | |
852 | return type; | |
853 | } | |
854 | /* | |
855 | * Otherwise, wait for some data to arrive, add it to the | |
856 | * buffer, and try again. | |
857 | */ | |
858 | memset(setp, 0, howmany(connection_in + 1, NFDBITS) * | |
859 | sizeof(fd_mask)); | |
860 | FD_SET(connection_in, setp); | |
861 | ||
862 | /* Wait for some data to arrive. */ | |
863 | while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && | |
864 | (errno == EAGAIN || errno == EINTR)) | |
865 | ; | |
866 | ||
867 | /* Read data from the socket. */ | |
868 | len = read(connection_in, buf, sizeof(buf)); | |
869 | if (len == 0) { | |
870 | logit("Connection closed by %.200s", get_remote_ipaddr()); | |
871 | cleanup_exit(255); | |
872 | } | |
873 | if (len < 0) | |
874 | fatal("Read from socket failed: %.100s", strerror(errno)); | |
875 | /* Append it to the buffer. */ | |
876 | packet_process_incoming(buf, len); | |
877 | } | |
878 | /* NOTREACHED */ | |
879 | } | |
880 | ||
881 | int | |
882 | packet_read(void) | |
883 | { | |
884 | return packet_read_seqnr(NULL); | |
885 | } | |
886 | ||
887 | /* | |
888 | * Waits until a packet has been received, verifies that its type matches | |
889 | * that given, and gives a fatal error and exits if there is a mismatch. | |
890 | */ | |
891 | ||
892 | void | |
893 | packet_read_expect(int expected_type) | |
894 | { | |
895 | int type; | |
896 | ||
897 | type = packet_read(); | |
898 | if (type != expected_type) | |
899 | packet_disconnect("Protocol error: expected packet type %d, got %d", | |
900 | expected_type, type); | |
901 | } | |
902 | ||
903 | /* Checks if a full packet is available in the data received so far via | |
904 | * packet_process_incoming. If so, reads the packet; otherwise returns | |
905 | * SSH_MSG_NONE. This does not wait for data from the connection. | |
906 | * | |
907 | * SSH_MSG_DISCONNECT is handled specially here. Also, | |
908 | * SSH_MSG_IGNORE messages are skipped by this function and are never returned | |
909 | * to higher levels. | |
910 | */ | |
911 | ||
912 | static int | |
913 | packet_read_poll1(void) | |
914 | { | |
915 | u_int len, padded_len; | |
916 | u_char *cp, type; | |
917 | u_int checksum, stored_checksum; | |
918 | ||
919 | /* Check if input size is less than minimum packet size. */ | |
920 | if (buffer_len(&input) < 4 + 8) | |
921 | return SSH_MSG_NONE; | |
922 | /* Get length of incoming packet. */ | |
923 | cp = buffer_ptr(&input); | |
924 | len = GET_32BIT(cp); | |
925 | if (len < 1 + 2 + 2 || len > 256 * 1024) | |
926 | packet_disconnect("Bad packet length %u.", len); | |
927 | padded_len = (len + 8) & ~7; | |
928 | ||
929 | /* Check if the packet has been entirely received. */ | |
930 | if (buffer_len(&input) < 4 + padded_len) | |
931 | return SSH_MSG_NONE; | |
932 | ||
933 | /* The entire packet is in buffer. */ | |
934 | ||
935 | /* Consume packet length. */ | |
936 | buffer_consume(&input, 4); | |
937 | ||
938 | /* | |
939 | * Cryptographic attack detector for ssh | |
940 | * (C)1998 CORE-SDI, Buenos Aires Argentina | |
941 | * Ariel Futoransky(futo@core-sdi.com) | |
942 | */ | |
943 | if (!receive_context.plaintext && | |
944 | detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) | |
945 | packet_disconnect("crc32 compensation attack: network attack detected"); | |
946 | ||
947 | /* Decrypt data to incoming_packet. */ | |
948 | buffer_clear(&incoming_packet); | |
949 | cp = buffer_append_space(&incoming_packet, padded_len); | |
950 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); | |
951 | ||
952 | buffer_consume(&input, padded_len); | |
953 | ||
954 | #ifdef PACKET_DEBUG | |
955 | fprintf(stderr, "read_poll plain: "); | |
956 | buffer_dump(&incoming_packet); | |
957 | #endif | |
958 | ||
959 | /* Compute packet checksum. */ | |
960 | checksum = ssh_crc32(buffer_ptr(&incoming_packet), | |
961 | buffer_len(&incoming_packet) - 4); | |
962 | ||
963 | /* Skip padding. */ | |
964 | buffer_consume(&incoming_packet, 8 - len % 8); | |
965 | ||
966 | /* Test check bytes. */ | |
967 | if (len != buffer_len(&incoming_packet)) | |
968 | packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", | |
969 | len, buffer_len(&incoming_packet)); | |
970 | ||
971 | cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; | |
972 | stored_checksum = GET_32BIT(cp); | |
973 | if (checksum != stored_checksum) | |
974 | packet_disconnect("Corrupted check bytes on input."); | |
975 | buffer_consume_end(&incoming_packet, 4); | |
976 | ||
977 | if (packet_compression) { | |
978 | buffer_clear(&compression_buffer); | |
979 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
980 | buffer_clear(&incoming_packet); | |
981 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
982 | buffer_len(&compression_buffer)); | |
983 | } | |
984 | type = buffer_get_char(&incoming_packet); | |
985 | return type; | |
986 | } | |
987 | ||
988 | static int | |
989 | packet_read_poll2(u_int32_t *seqnr_p) | |
990 | { | |
991 | static u_int packet_length = 0; | |
992 | u_int padlen, need; | |
993 | u_char *macbuf, *cp, type; | |
994 | int maclen, block_size; | |
995 | Enc *enc = NULL; | |
996 | Mac *mac = NULL; | |
997 | Comp *comp = NULL; | |
998 | ||
999 | if (newkeys[MODE_IN] != NULL) { | |
1000 | enc = &newkeys[MODE_IN]->enc; | |
1001 | mac = &newkeys[MODE_IN]->mac; | |
1002 | comp = &newkeys[MODE_IN]->comp; | |
1003 | } | |
1004 | maclen = mac && mac->enabled ? mac->mac_len : 0; | |
1005 | block_size = enc ? enc->block_size : 8; | |
1006 | ||
1007 | if (packet_length == 0) { | |
1008 | /* | |
1009 | * check if input size is less than the cipher block size, | |
1010 | * decrypt first block and extract length of incoming packet | |
1011 | */ | |
1012 | if (buffer_len(&input) < block_size) | |
1013 | return SSH_MSG_NONE; | |
1014 | buffer_clear(&incoming_packet); | |
1015 | cp = buffer_append_space(&incoming_packet, block_size); | |
1016 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), | |
1017 | block_size); | |
1018 | cp = buffer_ptr(&incoming_packet); | |
1019 | packet_length = GET_32BIT(cp); | |
1020 | if (packet_length < 1 + 4 || packet_length > 256 * 1024) { | |
1021 | #ifdef PACKET_DEBUG | |
1022 | buffer_dump(&incoming_packet); | |
1023 | #endif | |
1024 | packet_disconnect("Bad packet length %u.", packet_length); | |
1025 | } | |
1026 | DBG(debug("input: packet len %u", packet_length+4)); | |
1027 | buffer_consume(&input, block_size); | |
1028 | } | |
1029 | /* we have a partial packet of block_size bytes */ | |
1030 | need = 4 + packet_length - block_size; | |
1031 | DBG(debug("partial packet %d, need %d, maclen %d", block_size, | |
1032 | need, maclen)); | |
1033 | if (need % block_size != 0) | |
1034 | fatal("padding error: need %d block %d mod %d", | |
1035 | need, block_size, need % block_size); | |
1036 | /* | |
1037 | * check if the entire packet has been received and | |
1038 | * decrypt into incoming_packet | |
1039 | */ | |
1040 | if (buffer_len(&input) < need + maclen) | |
1041 | return SSH_MSG_NONE; | |
1042 | #ifdef PACKET_DEBUG | |
1043 | fprintf(stderr, "read_poll enc/full: "); | |
1044 | buffer_dump(&input); | |
1045 | #endif | |
1046 | cp = buffer_append_space(&incoming_packet, need); | |
1047 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); | |
1048 | buffer_consume(&input, need); | |
1049 | /* | |
1050 | * compute MAC over seqnr and packet, | |
1051 | * increment sequence number for incoming packet | |
1052 | */ | |
1053 | if (mac && mac->enabled) { | |
1054 | macbuf = mac_compute(mac, p_read.seqnr, | |
1055 | buffer_ptr(&incoming_packet), | |
1056 | buffer_len(&incoming_packet)); | |
1057 | if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) | |
1058 | packet_disconnect("Corrupted MAC on input."); | |
1059 | DBG(debug("MAC #%d ok", p_read.seqnr)); | |
1060 | buffer_consume(&input, mac->mac_len); | |
1061 | } | |
1062 | if (seqnr_p != NULL) | |
1063 | *seqnr_p = p_read.seqnr; | |
1064 | if (++p_read.seqnr == 0) | |
1065 | logit("incoming seqnr wraps around"); | |
1066 | if (++p_read.packets == 0) | |
1067 | if (!(datafellows & SSH_BUG_NOREKEY)) | |
1068 | fatal("XXX too many packets with same key"); | |
1069 | p_read.blocks += (packet_length + 4) / block_size; | |
1070 | ||
1071 | /* get padlen */ | |
1072 | cp = buffer_ptr(&incoming_packet); | |
1073 | padlen = cp[4]; | |
1074 | DBG(debug("input: padlen %d", padlen)); | |
1075 | if (padlen < 4) | |
1076 | packet_disconnect("Corrupted padlen %d on input.", padlen); | |
1077 | ||
1078 | /* skip packet size + padlen, discard padding */ | |
1079 | buffer_consume(&incoming_packet, 4 + 1); | |
1080 | buffer_consume_end(&incoming_packet, padlen); | |
1081 | ||
1082 | DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); | |
1083 | if (comp && comp->enabled) { | |
1084 | buffer_clear(&compression_buffer); | |
1085 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
1086 | buffer_clear(&incoming_packet); | |
1087 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
1088 | buffer_len(&compression_buffer)); | |
1089 | DBG(debug("input: len after de-compress %d", | |
1090 | buffer_len(&incoming_packet))); | |
1091 | } | |
1092 | /* | |
1093 | * get packet type, implies consume. | |
1094 | * return length of payload (without type field) | |
1095 | */ | |
1096 | type = buffer_get_char(&incoming_packet); | |
1097 | if (type == SSH2_MSG_NEWKEYS) | |
1098 | set_newkeys(MODE_IN); | |
1099 | #ifdef PACKET_DEBUG | |
1100 | fprintf(stderr, "read/plain[%d]:\r\n", type); | |
1101 | buffer_dump(&incoming_packet); | |
1102 | #endif | |
1103 | /* reset for next packet */ | |
1104 | packet_length = 0; | |
1105 | return type; | |
1106 | } | |
1107 | ||
1108 | int | |
1109 | packet_read_poll_seqnr(u_int32_t *seqnr_p) | |
1110 | { | |
1111 | u_int reason, seqnr; | |
1112 | u_char type; | |
1113 | char *msg; | |
1114 | ||
1115 | for (;;) { | |
1116 | if (compat20) { | |
1117 | type = packet_read_poll2(seqnr_p); | |
1118 | if (type) | |
1119 | DBG(debug("received packet type %d", type)); | |
1120 | switch (type) { | |
1121 | case SSH2_MSG_IGNORE: | |
1122 | break; | |
1123 | case SSH2_MSG_DEBUG: | |
1124 | packet_get_char(); | |
1125 | msg = packet_get_string(NULL); | |
1126 | debug("Remote: %.900s", msg); | |
1127 | xfree(msg); | |
1128 | msg = packet_get_string(NULL); | |
1129 | xfree(msg); | |
1130 | break; | |
1131 | case SSH2_MSG_DISCONNECT: | |
1132 | reason = packet_get_int(); | |
1133 | msg = packet_get_string(NULL); | |
1134 | logit("Received disconnect from %s: %u: %.400s", | |
1135 | get_remote_ipaddr(), reason, msg); | |
1136 | xfree(msg); | |
1137 | cleanup_exit(255); | |
1138 | break; | |
1139 | case SSH2_MSG_UNIMPLEMENTED: | |
1140 | seqnr = packet_get_int(); | |
1141 | debug("Received SSH2_MSG_UNIMPLEMENTED for %u", | |
1142 | seqnr); | |
1143 | break; | |
1144 | default: | |
1145 | return type; | |
1146 | break; | |
1147 | } | |
1148 | } else { | |
1149 | type = packet_read_poll1(); | |
1150 | switch (type) { | |
1151 | case SSH_MSG_IGNORE: | |
1152 | break; | |
1153 | case SSH_MSG_DEBUG: | |
1154 | msg = packet_get_string(NULL); | |
1155 | debug("Remote: %.900s", msg); | |
1156 | xfree(msg); | |
1157 | break; | |
1158 | case SSH_MSG_DISCONNECT: | |
1159 | msg = packet_get_string(NULL); | |
1160 | logit("Received disconnect from %s: %.400s", | |
1161 | get_remote_ipaddr(), msg); | |
1162 | cleanup_exit(255); | |
1163 | xfree(msg); | |
1164 | break; | |
1165 | default: | |
1166 | if (type) | |
1167 | DBG(debug("received packet type %d", type)); | |
1168 | return type; | |
1169 | break; | |
1170 | } | |
1171 | } | |
1172 | } | |
1173 | } | |
1174 | ||
1175 | int | |
1176 | packet_read_poll(void) | |
1177 | { | |
1178 | return packet_read_poll_seqnr(NULL); | |
1179 | } | |
1180 | ||
1181 | /* | |
1182 | * Buffers the given amount of input characters. This is intended to be used | |
1183 | * together with packet_read_poll. | |
1184 | */ | |
1185 | ||
1186 | void | |
1187 | packet_process_incoming(const char *buf, u_int len) | |
1188 | { | |
1189 | buffer_append(&input, buf, len); | |
1190 | } | |
1191 | ||
1192 | /* Returns a character from the packet. */ | |
1193 | ||
1194 | u_int | |
1195 | packet_get_char(void) | |
1196 | { | |
1197 | char ch; | |
1198 | ||
1199 | buffer_get(&incoming_packet, &ch, 1); | |
1200 | return (u_char) ch; | |
1201 | } | |
1202 | ||
1203 | /* Returns an integer from the packet data. */ | |
1204 | ||
1205 | u_int | |
1206 | packet_get_int(void) | |
1207 | { | |
1208 | return buffer_get_int(&incoming_packet); | |
1209 | } | |
1210 | ||
1211 | /* | |
1212 | * Returns an arbitrary precision integer from the packet data. The integer | |
1213 | * must have been initialized before this call. | |
1214 | */ | |
1215 | ||
1216 | void | |
1217 | packet_get_bignum(BIGNUM * value) | |
1218 | { | |
1219 | buffer_get_bignum(&incoming_packet, value); | |
1220 | } | |
1221 | ||
1222 | void | |
1223 | packet_get_bignum2(BIGNUM * value) | |
1224 | { | |
1225 | buffer_get_bignum2(&incoming_packet, value); | |
1226 | } | |
1227 | ||
1228 | void * | |
1229 | packet_get_raw(int *length_ptr) | |
1230 | { | |
1231 | int bytes = buffer_len(&incoming_packet); | |
1232 | ||
1233 | if (length_ptr != NULL) | |
1234 | *length_ptr = bytes; | |
1235 | return buffer_ptr(&incoming_packet); | |
1236 | } | |
1237 | ||
1238 | int | |
1239 | packet_remaining(void) | |
1240 | { | |
1241 | return buffer_len(&incoming_packet); | |
1242 | } | |
1243 | ||
1244 | /* | |
1245 | * Returns a string from the packet data. The string is allocated using | |
1246 | * xmalloc; it is the responsibility of the calling program to free it when | |
1247 | * no longer needed. The length_ptr argument may be NULL, or point to an | |
1248 | * integer into which the length of the string is stored. | |
1249 | */ | |
1250 | ||
1251 | void * | |
1252 | packet_get_string(u_int *length_ptr) | |
1253 | { | |
1254 | return buffer_get_string(&incoming_packet, length_ptr); | |
1255 | } | |
1256 | ||
1257 | /* | |
1258 | * Sends a diagnostic message from the server to the client. This message | |
1259 | * can be sent at any time (but not while constructing another message). The | |
1260 | * message is printed immediately, but only if the client is being executed | |
1261 | * in verbose mode. These messages are primarily intended to ease debugging | |
1262 | * authentication problems. The length of the formatted message must not | |
1263 | * exceed 1024 bytes. This will automatically call packet_write_wait. | |
1264 | */ | |
1265 | ||
1266 | void | |
1267 | packet_send_debug(const char *fmt,...) | |
1268 | { | |
1269 | char buf[1024]; | |
1270 | va_list args; | |
1271 | ||
1272 | if (compat20 && (datafellows & SSH_BUG_DEBUG)) | |
1273 | return; | |
1274 | ||
1275 | va_start(args, fmt); | |
1276 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1277 | va_end(args); | |
1278 | ||
1279 | if (compat20) { | |
1280 | packet_start(SSH2_MSG_DEBUG); | |
1281 | packet_put_char(0); /* bool: always display */ | |
1282 | packet_put_cstring(buf); | |
1283 | packet_put_cstring(""); | |
1284 | } else { | |
1285 | packet_start(SSH_MSG_DEBUG); | |
1286 | packet_put_cstring(buf); | |
1287 | } | |
1288 | packet_send(); | |
1289 | packet_write_wait(); | |
1290 | } | |
1291 | ||
1292 | /* | |
1293 | * Logs the error plus constructs and sends a disconnect packet, closes the | |
1294 | * connection, and exits. This function never returns. The error message | |
1295 | * should not contain a newline. The length of the formatted message must | |
1296 | * not exceed 1024 bytes. | |
1297 | */ | |
1298 | ||
1299 | void | |
1300 | packet_disconnect(const char *fmt,...) | |
1301 | { | |
1302 | char buf[1024]; | |
1303 | va_list args; | |
1304 | static int disconnecting = 0; | |
1305 | ||
1306 | if (disconnecting) /* Guard against recursive invocations. */ | |
1307 | fatal("packet_disconnect called recursively."); | |
1308 | disconnecting = 1; | |
1309 | ||
1310 | /* | |
1311 | * Format the message. Note that the caller must make sure the | |
1312 | * message is of limited size. | |
1313 | */ | |
1314 | va_start(args, fmt); | |
1315 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1316 | va_end(args); | |
1317 | ||
1318 | /* Display the error locally */ | |
1319 | logit("Disconnecting: %.100s", buf); | |
1320 | ||
1321 | /* Send the disconnect message to the other side, and wait for it to get sent. */ | |
1322 | if (compat20) { | |
1323 | packet_start(SSH2_MSG_DISCONNECT); | |
1324 | packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); | |
1325 | packet_put_cstring(buf); | |
1326 | packet_put_cstring(""); | |
1327 | } else { | |
1328 | packet_start(SSH_MSG_DISCONNECT); | |
1329 | packet_put_cstring(buf); | |
1330 | } | |
1331 | packet_send(); | |
1332 | packet_write_wait(); | |
1333 | ||
1334 | /* Stop listening for connections. */ | |
1335 | channel_close_all(); | |
1336 | ||
1337 | /* Close the connection. */ | |
1338 | packet_close(); | |
1339 | cleanup_exit(255); | |
1340 | } | |
1341 | ||
1342 | /* Checks if there is any buffered output, and tries to write some of the output. */ | |
1343 | ||
1344 | void | |
1345 | packet_write_poll(void) | |
1346 | { | |
1347 | int len = buffer_len(&output); | |
1348 | ||
1349 | if (len > 0) { | |
1350 | len = write(connection_out, buffer_ptr(&output), len); | |
1351 | if (len <= 0) { | |
1352 | if (errno == EAGAIN) | |
1353 | return; | |
1354 | else | |
1355 | fatal("Write failed: %.100s", strerror(errno)); | |
1356 | } | |
1357 | buffer_consume(&output, len); | |
1358 | } | |
1359 | } | |
1360 | ||
1361 | /* | |
1362 | * Calls packet_write_poll repeatedly until all pending output data has been | |
1363 | * written. | |
1364 | */ | |
1365 | ||
1366 | void | |
1367 | packet_write_wait(void) | |
1368 | { | |
1369 | fd_set *setp; | |
1370 | ||
1371 | setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * | |
1372 | sizeof(fd_mask)); | |
1373 | packet_write_poll(); | |
1374 | while (packet_have_data_to_write()) { | |
1375 | memset(setp, 0, howmany(connection_out + 1, NFDBITS) * | |
1376 | sizeof(fd_mask)); | |
1377 | FD_SET(connection_out, setp); | |
1378 | while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && | |
1379 | (errno == EAGAIN || errno == EINTR)) | |
1380 | ; | |
1381 | packet_write_poll(); | |
1382 | } | |
1383 | xfree(setp); | |
1384 | } | |
1385 | ||
1386 | /* Returns true if there is buffered data to write to the connection. */ | |
1387 | ||
1388 | int | |
1389 | packet_have_data_to_write(void) | |
1390 | { | |
1391 | return buffer_len(&output) != 0; | |
1392 | } | |
1393 | ||
1394 | /* Returns true if there is not too much data to write to the connection. */ | |
1395 | ||
1396 | int | |
1397 | packet_not_very_much_data_to_write(void) | |
1398 | { | |
1399 | if (interactive_mode) | |
1400 | return buffer_len(&output) < 16384; | |
1401 | else | |
1402 | return buffer_len(&output) < 128 * 1024; | |
1403 | } | |
1404 | ||
1405 | ||
1406 | static void | |
1407 | packet_set_tos(int interactive) | |
1408 | { | |
1409 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) | |
1410 | int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; | |
1411 | ||
1412 | if (!packet_connection_is_on_socket() || | |
1413 | !packet_connection_is_ipv4()) | |
1414 | return; | |
1415 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, | |
1416 | sizeof(tos)) < 0) | |
1417 | error("setsockopt IP_TOS %d: %.100s:", | |
1418 | tos, strerror(errno)); | |
1419 | #endif | |
1420 | } | |
1421 | ||
1422 | /* Informs that the current session is interactive. Sets IP flags for that. */ | |
1423 | ||
1424 | void | |
1425 | packet_set_interactive(int interactive) | |
1426 | { | |
1427 | static int called = 0; | |
1428 | ||
1429 | if (called) | |
1430 | return; | |
1431 | called = 1; | |
1432 | ||
1433 | /* Record that we are in interactive mode. */ | |
1434 | interactive_mode = interactive; | |
1435 | ||
1436 | /* Only set socket options if using a socket. */ | |
1437 | if (!packet_connection_is_on_socket()) | |
1438 | return; | |
1439 | if (interactive) | |
1440 | set_nodelay(connection_in); | |
1441 | packet_set_tos(interactive); | |
1442 | } | |
1443 | ||
1444 | /* Returns true if the current connection is interactive. */ | |
1445 | ||
1446 | int | |
1447 | packet_is_interactive(void) | |
1448 | { | |
1449 | return interactive_mode; | |
1450 | } | |
1451 | ||
1452 | u_int | |
1453 | packet_set_maxsize(u_int s) | |
1454 | { | |
1455 | static int called = 0; | |
1456 | ||
1457 | if (called) { | |
1458 | logit("packet_set_maxsize: called twice: old %d new %d", | |
1459 | max_packet_size, s); | |
1460 | return -1; | |
1461 | } | |
1462 | if (s < 4 * 1024 || s > 1024 * 1024) { | |
1463 | logit("packet_set_maxsize: bad size %d", s); | |
1464 | return -1; | |
1465 | } | |
1466 | called = 1; | |
1467 | debug("packet_set_maxsize: setting to %d", s); | |
1468 | max_packet_size = s; | |
1469 | return s; | |
1470 | } | |
1471 | ||
1472 | /* roundup current message to pad bytes */ | |
1473 | void | |
1474 | packet_add_padding(u_char pad) | |
1475 | { | |
1476 | extra_pad = pad; | |
1477 | } | |
1478 | ||
1479 | /* | |
1480 | * 9.2. Ignored Data Message | |
1481 | * | |
1482 | * byte SSH_MSG_IGNORE | |
1483 | * string data | |
1484 | * | |
1485 | * All implementations MUST understand (and ignore) this message at any | |
1486 | * time (after receiving the protocol version). No implementation is | |
1487 | * required to send them. This message can be used as an additional | |
1488 | * protection measure against advanced traffic analysis techniques. | |
1489 | */ | |
1490 | void | |
1491 | packet_send_ignore(int nbytes) | |
1492 | { | |
1493 | u_int32_t rand = 0; | |
1494 | int i; | |
1495 | ||
1496 | packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); | |
1497 | packet_put_int(nbytes); | |
1498 | for (i = 0; i < nbytes; i++) { | |
1499 | if (i % 4 == 0) | |
1500 | rand = arc4random(); | |
1501 | packet_put_char(rand & 0xff); | |
1502 | rand >>= 8; | |
1503 | } | |
1504 | } | |
1505 | ||
1506 | #define MAX_PACKETS (1<<31) | |
1507 | int | |
1508 | packet_need_rekeying(void) | |
1509 | { | |
1510 | if (datafellows & SSH_BUG_NOREKEY) | |
1511 | return 0; | |
1512 | return | |
1513 | (p_send.packets > MAX_PACKETS) || | |
1514 | (p_read.packets > MAX_PACKETS) || | |
1515 | (max_blocks_out && (p_send.blocks > max_blocks_out)) || | |
1516 | (max_blocks_in && (p_read.blocks > max_blocks_in)); | |
1517 | } | |
1518 | ||
1519 | void | |
1520 | packet_set_rekey_limit(u_int32_t bytes) | |
1521 | { | |
1522 | rekey_limit = bytes; | |
1523 | } |