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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 1.121 2006/02/08 14:38:18 stevesk Exp $"); | |
41 | ||
42 | #include "openbsd-compat/sys-queue.h" | |
43 | #include <netinet/in_systm.h> | |
44 | #include <netinet/ip.h> | |
45 | ||
46 | #include "xmalloc.h" | |
47 | #include "buffer.h" | |
48 | #include "packet.h" | |
49 | #include "bufaux.h" | |
50 | #include "crc32.h" | |
51 | #include "getput.h" | |
52 | ||
53 | #include "compress.h" | |
54 | #include "deattack.h" | |
55 | #include "channels.h" | |
56 | ||
57 | #include "compat.h" | |
58 | #include "ssh1.h" | |
59 | #include "ssh2.h" | |
60 | ||
61 | #include "cipher.h" | |
62 | #include "kex.h" | |
63 | #include "mac.h" | |
64 | #include "log.h" | |
65 | #include "canohost.h" | |
66 | #include "misc.h" | |
67 | #include "ssh.h" | |
68 | ||
69 | #ifdef PACKET_DEBUG | |
70 | #define DBG(x) x | |
71 | #else | |
72 | #define DBG(x) | |
73 | #endif | |
74 | ||
75 | /* | |
76 | * This variable contains the file descriptors used for communicating with | |
77 | * the other side. connection_in is used for reading; connection_out for | |
78 | * writing. These can be the same descriptor, in which case it is assumed to | |
79 | * be a socket. | |
80 | */ | |
81 | static int connection_in = -1; | |
82 | static int connection_out = -1; | |
83 | ||
84 | /* Protocol flags for the remote side. */ | |
85 | static u_int remote_protocol_flags = 0; | |
86 | ||
87 | /* Encryption context for receiving data. This is only used for decryption. */ | |
88 | static CipherContext receive_context; | |
89 | ||
90 | /* Encryption context for sending data. This is only used for encryption. */ | |
91 | static CipherContext send_context; | |
92 | ||
93 | /* Buffer for raw input data from the socket. */ | |
94 | Buffer input; | |
95 | ||
96 | /* Buffer for raw output data going to the socket. */ | |
97 | Buffer output; | |
98 | ||
99 | /* Buffer for the partial outgoing packet being constructed. */ | |
100 | static Buffer outgoing_packet; | |
101 | ||
102 | /* Buffer for the incoming packet currently being processed. */ | |
103 | static Buffer incoming_packet; | |
104 | ||
105 | /* Scratch buffer for packet compression/decompression. */ | |
106 | static Buffer compression_buffer; | |
107 | static int compression_buffer_ready = 0; | |
108 | ||
109 | /* Flag indicating whether packet compression/decompression is enabled. */ | |
110 | static int packet_compression = 0; | |
111 | ||
112 | /* default maximum packet size */ | |
113 | u_int max_packet_size = 32768; | |
114 | ||
115 | /* Flag indicating whether this module has been initialized. */ | |
116 | static int initialized = 0; | |
117 | ||
118 | /* Set to true if the connection is interactive. */ | |
119 | static int interactive_mode = 0; | |
120 | ||
121 | /* Set to true if we are the server side. */ | |
122 | static int server_side = 0; | |
123 | ||
124 | /* Set to true if we are authenticated. */ | |
125 | static int after_authentication = 0; | |
126 | ||
127 | /* Session key information for Encryption and MAC */ | |
128 | Newkeys *newkeys[MODE_MAX]; | |
129 | static struct packet_state { | |
130 | u_int32_t seqnr; | |
131 | u_int32_t packets; | |
132 | u_int64_t blocks; | |
133 | } p_read, p_send; | |
134 | ||
135 | static u_int64_t max_blocks_in, max_blocks_out; | |
136 | static u_int32_t rekey_limit; | |
137 | ||
138 | /* Session key for protocol v1 */ | |
139 | static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; | |
140 | static u_int ssh1_keylen; | |
141 | ||
142 | /* roundup current message to extra_pad bytes */ | |
143 | static u_char extra_pad = 0; | |
144 | ||
145 | struct packet { | |
146 | TAILQ_ENTRY(packet) next; | |
147 | u_char type; | |
148 | Buffer payload; | |
149 | }; | |
150 | TAILQ_HEAD(, packet) outgoing; | |
151 | ||
152 | /* | |
153 | * Sets the descriptors used for communication. Disables encryption until | |
154 | * packet_set_encryption_key is called. | |
155 | */ | |
156 | void | |
157 | packet_set_connection(int fd_in, int fd_out) | |
158 | { | |
159 | Cipher *none = cipher_by_name("none"); | |
160 | ||
161 | if (none == NULL) | |
162 | fatal("packet_set_connection: cannot load cipher 'none'"); | |
163 | connection_in = fd_in; | |
164 | connection_out = fd_out; | |
165 | cipher_init(&send_context, none, (const u_char *)"", | |
166 | 0, NULL, 0, CIPHER_ENCRYPT); | |
167 | cipher_init(&receive_context, none, (const u_char *)"", | |
168 | 0, NULL, 0, CIPHER_DECRYPT); | |
169 | newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; | |
170 | if (!initialized) { | |
171 | initialized = 1; | |
172 | buffer_init(&input); | |
173 | buffer_init(&output); | |
174 | buffer_init(&outgoing_packet); | |
175 | buffer_init(&incoming_packet); | |
176 | TAILQ_INIT(&outgoing); | |
177 | } | |
178 | } | |
179 | ||
180 | /* Returns 1 if remote host is connected via socket, 0 if not. */ | |
181 | ||
182 | int | |
183 | packet_connection_is_on_socket(void) | |
184 | { | |
185 | struct sockaddr_storage from, to; | |
186 | socklen_t fromlen, tolen; | |
187 | ||
188 | /* filedescriptors in and out are the same, so it's a socket */ | |
189 | if (connection_in == connection_out) | |
190 | return 1; | |
191 | fromlen = sizeof(from); | |
192 | memset(&from, 0, sizeof(from)); | |
193 | if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) | |
194 | return 0; | |
195 | tolen = sizeof(to); | |
196 | memset(&to, 0, sizeof(to)); | |
197 | if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
198 | return 0; | |
199 | if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) | |
200 | return 0; | |
201 | if (from.ss_family != AF_INET && from.ss_family != AF_INET6) | |
202 | return 0; | |
203 | return 1; | |
204 | } | |
205 | ||
206 | /* | |
207 | * Exports an IV from the CipherContext required to export the key | |
208 | * state back from the unprivileged child to the privileged parent | |
209 | * process. | |
210 | */ | |
211 | ||
212 | void | |
213 | packet_get_keyiv(int mode, u_char *iv, u_int len) | |
214 | { | |
215 | CipherContext *cc; | |
216 | ||
217 | if (mode == MODE_OUT) | |
218 | cc = &send_context; | |
219 | else | |
220 | cc = &receive_context; | |
221 | ||
222 | cipher_get_keyiv(cc, iv, len); | |
223 | } | |
224 | ||
225 | int | |
226 | packet_get_keycontext(int mode, u_char *dat) | |
227 | { | |
228 | CipherContext *cc; | |
229 | ||
230 | if (mode == MODE_OUT) | |
231 | cc = &send_context; | |
232 | else | |
233 | cc = &receive_context; | |
234 | ||
235 | return (cipher_get_keycontext(cc, dat)); | |
236 | } | |
237 | ||
238 | void | |
239 | packet_set_keycontext(int mode, u_char *dat) | |
240 | { | |
241 | CipherContext *cc; | |
242 | ||
243 | if (mode == MODE_OUT) | |
244 | cc = &send_context; | |
245 | else | |
246 | cc = &receive_context; | |
247 | ||
248 | cipher_set_keycontext(cc, dat); | |
249 | } | |
250 | ||
251 | int | |
252 | packet_get_keyiv_len(int mode) | |
253 | { | |
254 | CipherContext *cc; | |
255 | ||
256 | if (mode == MODE_OUT) | |
257 | cc = &send_context; | |
258 | else | |
259 | cc = &receive_context; | |
260 | ||
261 | return (cipher_get_keyiv_len(cc)); | |
262 | } | |
263 | void | |
264 | packet_set_iv(int mode, u_char *dat) | |
265 | { | |
266 | CipherContext *cc; | |
267 | ||
268 | if (mode == MODE_OUT) | |
269 | cc = &send_context; | |
270 | else | |
271 | cc = &receive_context; | |
272 | ||
273 | cipher_set_keyiv(cc, dat); | |
274 | } | |
275 | int | |
276 | packet_get_ssh1_cipher(void) | |
277 | { | |
278 | return (cipher_get_number(receive_context.cipher)); | |
279 | } | |
280 | ||
281 | void | |
282 | packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets) | |
283 | { | |
284 | struct packet_state *state; | |
285 | ||
286 | state = (mode == MODE_IN) ? &p_read : &p_send; | |
287 | *seqnr = state->seqnr; | |
288 | *blocks = state->blocks; | |
289 | *packets = state->packets; | |
290 | } | |
291 | ||
292 | void | |
293 | packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets) | |
294 | { | |
295 | struct packet_state *state; | |
296 | ||
297 | state = (mode == MODE_IN) ? &p_read : &p_send; | |
298 | state->seqnr = seqnr; | |
299 | state->blocks = blocks; | |
300 | state->packets = packets; | |
301 | } | |
302 | ||
303 | /* returns 1 if connection is via ipv4 */ | |
304 | ||
305 | int | |
306 | packet_connection_is_ipv4(void) | |
307 | { | |
308 | struct sockaddr_storage to; | |
309 | socklen_t tolen = sizeof(to); | |
310 | ||
311 | memset(&to, 0, sizeof(to)); | |
312 | if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
313 | return 0; | |
314 | if (to.ss_family == AF_INET) | |
315 | return 1; | |
316 | #ifdef IPV4_IN_IPV6 | |
317 | if (to.ss_family == AF_INET6 && | |
318 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) | |
319 | return 1; | |
320 | #endif | |
321 | return 0; | |
322 | } | |
323 | ||
324 | /* Sets the connection into non-blocking mode. */ | |
325 | ||
326 | void | |
327 | packet_set_nonblocking(void) | |
328 | { | |
329 | /* Set the socket into non-blocking mode. */ | |
330 | set_nonblock(connection_in); | |
331 | ||
332 | if (connection_out != connection_in) | |
333 | set_nonblock(connection_out); | |
334 | } | |
335 | ||
336 | /* Returns the socket used for reading. */ | |
337 | ||
338 | int | |
339 | packet_get_connection_in(void) | |
340 | { | |
341 | return connection_in; | |
342 | } | |
343 | ||
344 | /* Returns the descriptor used for writing. */ | |
345 | ||
346 | int | |
347 | packet_get_connection_out(void) | |
348 | { | |
349 | return connection_out; | |
350 | } | |
351 | ||
352 | /* Closes the connection and clears and frees internal data structures. */ | |
353 | ||
354 | void | |
355 | packet_close(void) | |
356 | { | |
357 | if (!initialized) | |
358 | return; | |
359 | initialized = 0; | |
360 | if (connection_in == connection_out) { | |
361 | shutdown(connection_out, SHUT_RDWR); | |
362 | close(connection_out); | |
363 | } else { | |
364 | close(connection_in); | |
365 | close(connection_out); | |
366 | } | |
367 | buffer_free(&input); | |
368 | buffer_free(&output); | |
369 | buffer_free(&outgoing_packet); | |
370 | buffer_free(&incoming_packet); | |
371 | if (compression_buffer_ready) { | |
372 | buffer_free(&compression_buffer); | |
373 | buffer_compress_uninit(); | |
374 | } | |
375 | cipher_cleanup(&send_context); | |
376 | cipher_cleanup(&receive_context); | |
377 | } | |
378 | ||
379 | /* Sets remote side protocol flags. */ | |
380 | ||
381 | void | |
382 | packet_set_protocol_flags(u_int protocol_flags) | |
383 | { | |
384 | remote_protocol_flags = protocol_flags; | |
385 | } | |
386 | ||
387 | /* Returns the remote protocol flags set earlier by the above function. */ | |
388 | ||
389 | u_int | |
390 | packet_get_protocol_flags(void) | |
391 | { | |
392 | return remote_protocol_flags; | |
393 | } | |
394 | ||
395 | /* | |
396 | * Starts packet compression from the next packet on in both directions. | |
397 | * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. | |
398 | */ | |
399 | ||
400 | static void | |
401 | packet_init_compression(void) | |
402 | { | |
403 | if (compression_buffer_ready == 1) | |
404 | return; | |
405 | compression_buffer_ready = 1; | |
406 | buffer_init(&compression_buffer); | |
407 | } | |
408 | ||
409 | void | |
410 | packet_start_compression(int level) | |
411 | { | |
412 | if (packet_compression && !compat20) | |
413 | fatal("Compression already enabled."); | |
414 | packet_compression = 1; | |
415 | packet_init_compression(); | |
416 | buffer_compress_init_send(level); | |
417 | buffer_compress_init_recv(); | |
418 | } | |
419 | ||
420 | /* | |
421 | * Causes any further packets to be encrypted using the given key. The same | |
422 | * key is used for both sending and reception. However, both directions are | |
423 | * encrypted independently of each other. | |
424 | */ | |
425 | ||
426 | void | |
427 | packet_set_encryption_key(const u_char *key, u_int keylen, | |
428 | int number) | |
429 | { | |
430 | Cipher *cipher = cipher_by_number(number); | |
431 | ||
432 | if (cipher == NULL) | |
433 | fatal("packet_set_encryption_key: unknown cipher number %d", number); | |
434 | if (keylen < 20) | |
435 | fatal("packet_set_encryption_key: keylen too small: %d", keylen); | |
436 | if (keylen > SSH_SESSION_KEY_LENGTH) | |
437 | fatal("packet_set_encryption_key: keylen too big: %d", keylen); | |
438 | memcpy(ssh1_key, key, keylen); | |
439 | ssh1_keylen = keylen; | |
440 | cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); | |
441 | cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); | |
442 | } | |
443 | ||
444 | u_int | |
445 | packet_get_encryption_key(u_char *key) | |
446 | { | |
447 | if (key == NULL) | |
448 | return (ssh1_keylen); | |
449 | memcpy(key, ssh1_key, ssh1_keylen); | |
450 | return (ssh1_keylen); | |
451 | } | |
452 | ||
453 | /* Start constructing a packet to send. */ | |
454 | void | |
455 | packet_start(u_char type) | |
456 | { | |
457 | u_char buf[9]; | |
458 | int len; | |
459 | ||
460 | DBG(debug("packet_start[%d]", type)); | |
461 | len = compat20 ? 6 : 9; | |
462 | memset(buf, 0, len - 1); | |
463 | buf[len - 1] = type; | |
464 | buffer_clear(&outgoing_packet); | |
465 | buffer_append(&outgoing_packet, buf, len); | |
466 | } | |
467 | ||
468 | /* Append payload. */ | |
469 | void | |
470 | packet_put_char(int value) | |
471 | { | |
472 | char ch = value; | |
473 | ||
474 | buffer_append(&outgoing_packet, &ch, 1); | |
475 | } | |
476 | void | |
477 | packet_put_int(u_int value) | |
478 | { | |
479 | buffer_put_int(&outgoing_packet, value); | |
480 | } | |
481 | void | |
482 | packet_put_string(const void *buf, u_int len) | |
483 | { | |
484 | buffer_put_string(&outgoing_packet, buf, len); | |
485 | } | |
486 | void | |
487 | packet_put_cstring(const char *str) | |
488 | { | |
489 | buffer_put_cstring(&outgoing_packet, str); | |
490 | } | |
491 | void | |
492 | packet_put_raw(const void *buf, u_int len) | |
493 | { | |
494 | buffer_append(&outgoing_packet, buf, len); | |
495 | } | |
496 | void | |
497 | packet_put_bignum(BIGNUM * value) | |
498 | { | |
499 | buffer_put_bignum(&outgoing_packet, value); | |
500 | } | |
501 | void | |
502 | packet_put_bignum2(BIGNUM * value) | |
503 | { | |
504 | buffer_put_bignum2(&outgoing_packet, value); | |
505 | } | |
506 | ||
507 | /* | |
508 | * Finalizes and sends the packet. If the encryption key has been set, | |
509 | * encrypts the packet before sending. | |
510 | */ | |
511 | ||
512 | static void | |
513 | packet_send1(void) | |
514 | { | |
515 | u_char buf[8], *cp; | |
516 | int i, padding, len; | |
517 | u_int checksum; | |
518 | u_int32_t rnd = 0; | |
519 | ||
520 | /* | |
521 | * If using packet compression, compress the payload of the outgoing | |
522 | * packet. | |
523 | */ | |
524 | if (packet_compression) { | |
525 | buffer_clear(&compression_buffer); | |
526 | /* Skip padding. */ | |
527 | buffer_consume(&outgoing_packet, 8); | |
528 | /* padding */ | |
529 | buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); | |
530 | buffer_compress(&outgoing_packet, &compression_buffer); | |
531 | buffer_clear(&outgoing_packet); | |
532 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
533 | buffer_len(&compression_buffer)); | |
534 | } | |
535 | /* Compute packet length without padding (add checksum, remove padding). */ | |
536 | len = buffer_len(&outgoing_packet) + 4 - 8; | |
537 | ||
538 | /* Insert padding. Initialized to zero in packet_start1() */ | |
539 | padding = 8 - len % 8; | |
540 | if (!send_context.plaintext) { | |
541 | cp = buffer_ptr(&outgoing_packet); | |
542 | for (i = 0; i < padding; i++) { | |
543 | if (i % 4 == 0) | |
544 | rnd = arc4random(); | |
545 | cp[7 - i] = rnd & 0xff; | |
546 | rnd >>= 8; | |
547 | } | |
548 | } | |
549 | buffer_consume(&outgoing_packet, 8 - padding); | |
550 | ||
551 | /* Add check bytes. */ | |
552 | checksum = ssh_crc32(buffer_ptr(&outgoing_packet), | |
553 | buffer_len(&outgoing_packet)); | |
554 | PUT_32BIT(buf, checksum); | |
555 | buffer_append(&outgoing_packet, buf, 4); | |
556 | ||
557 | #ifdef PACKET_DEBUG | |
558 | fprintf(stderr, "packet_send plain: "); | |
559 | buffer_dump(&outgoing_packet); | |
560 | #endif | |
561 | ||
562 | /* Append to output. */ | |
563 | PUT_32BIT(buf, len); | |
564 | buffer_append(&output, buf, 4); | |
565 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); | |
566 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
567 | buffer_len(&outgoing_packet)); | |
568 | ||
569 | #ifdef PACKET_DEBUG | |
570 | fprintf(stderr, "encrypted: "); | |
571 | buffer_dump(&output); | |
572 | #endif | |
573 | ||
574 | buffer_clear(&outgoing_packet); | |
575 | ||
576 | /* | |
577 | * Note that the packet is now only buffered in output. It won't be | |
578 | * actually sent until packet_write_wait or packet_write_poll is | |
579 | * called. | |
580 | */ | |
581 | } | |
582 | ||
583 | void | |
584 | set_newkeys(int mode) | |
585 | { | |
586 | Enc *enc; | |
587 | Mac *mac; | |
588 | Comp *comp; | |
589 | CipherContext *cc; | |
590 | u_int64_t *max_blocks; | |
591 | int crypt_type; | |
592 | ||
593 | debug2("set_newkeys: mode %d", mode); | |
594 | ||
595 | if (mode == MODE_OUT) { | |
596 | cc = &send_context; | |
597 | crypt_type = CIPHER_ENCRYPT; | |
598 | p_send.packets = p_send.blocks = 0; | |
599 | max_blocks = &max_blocks_out; | |
600 | } else { | |
601 | cc = &receive_context; | |
602 | crypt_type = CIPHER_DECRYPT; | |
603 | p_read.packets = p_read.blocks = 0; | |
604 | max_blocks = &max_blocks_in; | |
605 | } | |
606 | if (newkeys[mode] != NULL) { | |
607 | debug("set_newkeys: rekeying"); | |
608 | cipher_cleanup(cc); | |
609 | enc = &newkeys[mode]->enc; | |
610 | mac = &newkeys[mode]->mac; | |
611 | comp = &newkeys[mode]->comp; | |
612 | memset(mac->key, 0, mac->key_len); | |
613 | xfree(enc->name); | |
614 | xfree(enc->iv); | |
615 | xfree(enc->key); | |
616 | xfree(mac->name); | |
617 | xfree(mac->key); | |
618 | xfree(comp->name); | |
619 | xfree(newkeys[mode]); | |
620 | } | |
621 | newkeys[mode] = kex_get_newkeys(mode); | |
622 | if (newkeys[mode] == NULL) | |
623 | fatal("newkeys: no keys for mode %d", mode); | |
624 | enc = &newkeys[mode]->enc; | |
625 | mac = &newkeys[mode]->mac; | |
626 | comp = &newkeys[mode]->comp; | |
627 | if (mac->md != NULL) | |
628 | mac->enabled = 1; | |
629 | DBG(debug("cipher_init_context: %d", mode)); | |
630 | cipher_init(cc, enc->cipher, enc->key, enc->key_len, | |
631 | enc->iv, enc->block_size, crypt_type); | |
632 | /* Deleting the keys does not gain extra security */ | |
633 | /* memset(enc->iv, 0, enc->block_size); | |
634 | memset(enc->key, 0, enc->key_len); */ | |
635 | if ((comp->type == COMP_ZLIB || | |
636 | (comp->type == COMP_DELAYED && after_authentication)) && | |
637 | comp->enabled == 0) { | |
638 | packet_init_compression(); | |
639 | if (mode == MODE_OUT) | |
640 | buffer_compress_init_send(6); | |
641 | else | |
642 | buffer_compress_init_recv(); | |
643 | comp->enabled = 1; | |
644 | } | |
645 | /* | |
646 | * The 2^(blocksize*2) limit is too expensive for 3DES, | |
647 | * blowfish, etc, so enforce a 1GB limit for small blocksizes. | |
648 | */ | |
649 | if (enc->block_size >= 16) | |
650 | *max_blocks = (u_int64_t)1 << (enc->block_size*2); | |
651 | else | |
652 | *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; | |
653 | if (rekey_limit) | |
654 | *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); | |
655 | } | |
656 | ||
657 | /* | |
658 | * Delayed compression for SSH2 is enabled after authentication: | |
659 | * This happans on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent, | |
660 | * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received. | |
661 | */ | |
662 | static void | |
663 | packet_enable_delayed_compress(void) | |
664 | { | |
665 | Comp *comp = NULL; | |
666 | int mode; | |
667 | ||
668 | /* | |
669 | * Remember that we are past the authentication step, so rekeying | |
670 | * with COMP_DELAYED will turn on compression immediately. | |
671 | */ | |
672 | after_authentication = 1; | |
673 | for (mode = 0; mode < MODE_MAX; mode++) { | |
674 | comp = &newkeys[mode]->comp; | |
675 | if (comp && !comp->enabled && comp->type == COMP_DELAYED) { | |
676 | packet_init_compression(); | |
677 | if (mode == MODE_OUT) | |
678 | buffer_compress_init_send(6); | |
679 | else | |
680 | buffer_compress_init_recv(); | |
681 | comp->enabled = 1; | |
682 | } | |
683 | } | |
684 | } | |
685 | ||
686 | /* | |
687 | * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) | |
688 | */ | |
689 | static void | |
690 | packet_send2_wrapped(void) | |
691 | { | |
692 | u_char type, *cp, *macbuf = NULL; | |
693 | u_char padlen, pad; | |
694 | u_int packet_length = 0; | |
695 | u_int i, len; | |
696 | u_int32_t rnd = 0; | |
697 | Enc *enc = NULL; | |
698 | Mac *mac = NULL; | |
699 | Comp *comp = NULL; | |
700 | int block_size; | |
701 | ||
702 | if (newkeys[MODE_OUT] != NULL) { | |
703 | enc = &newkeys[MODE_OUT]->enc; | |
704 | mac = &newkeys[MODE_OUT]->mac; | |
705 | comp = &newkeys[MODE_OUT]->comp; | |
706 | } | |
707 | block_size = enc ? enc->block_size : 8; | |
708 | ||
709 | cp = buffer_ptr(&outgoing_packet); | |
710 | type = cp[5]; | |
711 | ||
712 | #ifdef PACKET_DEBUG | |
713 | fprintf(stderr, "plain: "); | |
714 | buffer_dump(&outgoing_packet); | |
715 | #endif | |
716 | ||
717 | if (comp && comp->enabled) { | |
718 | len = buffer_len(&outgoing_packet); | |
719 | /* skip header, compress only payload */ | |
720 | buffer_consume(&outgoing_packet, 5); | |
721 | buffer_clear(&compression_buffer); | |
722 | buffer_compress(&outgoing_packet, &compression_buffer); | |
723 | buffer_clear(&outgoing_packet); | |
724 | buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); | |
725 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
726 | buffer_len(&compression_buffer)); | |
727 | DBG(debug("compression: raw %d compressed %d", len, | |
728 | buffer_len(&outgoing_packet))); | |
729 | } | |
730 | ||
731 | /* sizeof (packet_len + pad_len + payload) */ | |
732 | len = buffer_len(&outgoing_packet); | |
733 | ||
734 | /* | |
735 | * calc size of padding, alloc space, get random data, | |
736 | * minimum padding is 4 bytes | |
737 | */ | |
738 | padlen = block_size - (len % block_size); | |
739 | if (padlen < 4) | |
740 | padlen += block_size; | |
741 | if (extra_pad) { | |
742 | /* will wrap if extra_pad+padlen > 255 */ | |
743 | extra_pad = roundup(extra_pad, block_size); | |
744 | pad = extra_pad - ((len + padlen) % extra_pad); | |
745 | debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", | |
746 | pad, len, padlen, extra_pad); | |
747 | padlen += pad; | |
748 | extra_pad = 0; | |
749 | } | |
750 | cp = buffer_append_space(&outgoing_packet, padlen); | |
751 | if (enc && !send_context.plaintext) { | |
752 | /* random padding */ | |
753 | for (i = 0; i < padlen; i++) { | |
754 | if (i % 4 == 0) | |
755 | rnd = arc4random(); | |
756 | cp[i] = rnd & 0xff; | |
757 | rnd >>= 8; | |
758 | } | |
759 | } else { | |
760 | /* clear padding */ | |
761 | memset(cp, 0, padlen); | |
762 | } | |
763 | /* packet_length includes payload, padding and padding length field */ | |
764 | packet_length = buffer_len(&outgoing_packet) - 4; | |
765 | cp = buffer_ptr(&outgoing_packet); | |
766 | PUT_32BIT(cp, packet_length); | |
767 | cp[4] = padlen; | |
768 | DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); | |
769 | ||
770 | /* compute MAC over seqnr and packet(length fields, payload, padding) */ | |
771 | if (mac && mac->enabled) { | |
772 | macbuf = mac_compute(mac, p_send.seqnr, | |
773 | buffer_ptr(&outgoing_packet), | |
774 | buffer_len(&outgoing_packet)); | |
775 | DBG(debug("done calc MAC out #%d", p_send.seqnr)); | |
776 | } | |
777 | /* encrypt packet and append to output buffer. */ | |
778 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); | |
779 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
780 | buffer_len(&outgoing_packet)); | |
781 | /* append unencrypted MAC */ | |
782 | if (mac && mac->enabled) | |
783 | buffer_append(&output, (char *)macbuf, mac->mac_len); | |
784 | #ifdef PACKET_DEBUG | |
785 | fprintf(stderr, "encrypted: "); | |
786 | buffer_dump(&output); | |
787 | #endif | |
788 | /* increment sequence number for outgoing packets */ | |
789 | if (++p_send.seqnr == 0) | |
790 | logit("outgoing seqnr wraps around"); | |
791 | if (++p_send.packets == 0) | |
792 | if (!(datafellows & SSH_BUG_NOREKEY)) | |
793 | fatal("XXX too many packets with same key"); | |
794 | p_send.blocks += (packet_length + 4) / block_size; | |
795 | buffer_clear(&outgoing_packet); | |
796 | ||
797 | if (type == SSH2_MSG_NEWKEYS) | |
798 | set_newkeys(MODE_OUT); | |
799 | else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side) | |
800 | packet_enable_delayed_compress(); | |
801 | } | |
802 | ||
803 | static void | |
804 | packet_send2(void) | |
805 | { | |
806 | static int rekeying = 0; | |
807 | struct packet *p; | |
808 | u_char type, *cp; | |
809 | ||
810 | cp = buffer_ptr(&outgoing_packet); | |
811 | type = cp[5]; | |
812 | ||
813 | /* during rekeying we can only send key exchange messages */ | |
814 | if (rekeying) { | |
815 | if (!((type >= SSH2_MSG_TRANSPORT_MIN) && | |
816 | (type <= SSH2_MSG_TRANSPORT_MAX))) { | |
817 | debug("enqueue packet: %u", type); | |
818 | p = xmalloc(sizeof(*p)); | |
819 | p->type = type; | |
820 | memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); | |
821 | buffer_init(&outgoing_packet); | |
822 | TAILQ_INSERT_TAIL(&outgoing, p, next); | |
823 | return; | |
824 | } | |
825 | } | |
826 | ||
827 | /* rekeying starts with sending KEXINIT */ | |
828 | if (type == SSH2_MSG_KEXINIT) | |
829 | rekeying = 1; | |
830 | ||
831 | packet_send2_wrapped(); | |
832 | ||
833 | /* after a NEWKEYS message we can send the complete queue */ | |
834 | if (type == SSH2_MSG_NEWKEYS) { | |
835 | rekeying = 0; | |
836 | while ((p = TAILQ_FIRST(&outgoing))) { | |
837 | type = p->type; | |
838 | debug("dequeue packet: %u", type); | |
839 | buffer_free(&outgoing_packet); | |
840 | memcpy(&outgoing_packet, &p->payload, | |
841 | sizeof(Buffer)); | |
842 | TAILQ_REMOVE(&outgoing, p, next); | |
843 | xfree(p); | |
844 | packet_send2_wrapped(); | |
845 | } | |
846 | } | |
847 | } | |
848 | ||
849 | void | |
850 | packet_send(void) | |
851 | { | |
852 | if (compat20) | |
853 | packet_send2(); | |
854 | else | |
855 | packet_send1(); | |
856 | DBG(debug("packet_send done")); | |
857 | } | |
858 | ||
859 | /* | |
860 | * Waits until a packet has been received, and returns its type. Note that | |
861 | * no other data is processed until this returns, so this function should not | |
862 | * be used during the interactive session. | |
863 | */ | |
864 | ||
865 | int | |
866 | packet_read_seqnr(u_int32_t *seqnr_p) | |
867 | { | |
868 | int type, len; | |
869 | fd_set *setp; | |
870 | char buf[8192]; | |
871 | DBG(debug("packet_read()")); | |
872 | ||
873 | setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * | |
874 | sizeof(fd_mask)); | |
875 | ||
876 | /* Since we are blocking, ensure that all written packets have been sent. */ | |
877 | packet_write_wait(); | |
878 | ||
879 | /* Stay in the loop until we have received a complete packet. */ | |
880 | for (;;) { | |
881 | /* Try to read a packet from the buffer. */ | |
882 | type = packet_read_poll_seqnr(seqnr_p); | |
883 | if (!compat20 && ( | |
884 | type == SSH_SMSG_SUCCESS | |
885 | || type == SSH_SMSG_FAILURE | |
886 | || type == SSH_CMSG_EOF | |
887 | || type == SSH_CMSG_EXIT_CONFIRMATION)) | |
888 | packet_check_eom(); | |
889 | /* If we got a packet, return it. */ | |
890 | if (type != SSH_MSG_NONE) { | |
891 | xfree(setp); | |
892 | return type; | |
893 | } | |
894 | /* | |
895 | * Otherwise, wait for some data to arrive, add it to the | |
896 | * buffer, and try again. | |
897 | */ | |
898 | memset(setp, 0, howmany(connection_in + 1, NFDBITS) * | |
899 | sizeof(fd_mask)); | |
900 | FD_SET(connection_in, setp); | |
901 | ||
902 | /* Wait for some data to arrive. */ | |
903 | while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && | |
904 | (errno == EAGAIN || errno == EINTR)) | |
905 | ; | |
906 | ||
907 | /* Read data from the socket. */ | |
908 | len = read(connection_in, buf, sizeof(buf)); | |
909 | if (len == 0) { | |
910 | logit("Connection closed by %.200s", get_remote_ipaddr()); | |
911 | cleanup_exit(255); | |
912 | } | |
913 | if (len < 0) | |
914 | fatal("Read from socket failed: %.100s", strerror(errno)); | |
915 | /* Append it to the buffer. */ | |
916 | packet_process_incoming(buf, len); | |
917 | } | |
918 | /* NOTREACHED */ | |
919 | } | |
920 | ||
921 | int | |
922 | packet_read(void) | |
923 | { | |
924 | return packet_read_seqnr(NULL); | |
925 | } | |
926 | ||
927 | /* | |
928 | * Waits until a packet has been received, verifies that its type matches | |
929 | * that given, and gives a fatal error and exits if there is a mismatch. | |
930 | */ | |
931 | ||
932 | void | |
933 | packet_read_expect(int expected_type) | |
934 | { | |
935 | int type; | |
936 | ||
937 | type = packet_read(); | |
938 | if (type != expected_type) | |
939 | packet_disconnect("Protocol error: expected packet type %d, got %d", | |
940 | expected_type, type); | |
941 | } | |
942 | ||
943 | /* Checks if a full packet is available in the data received so far via | |
944 | * packet_process_incoming. If so, reads the packet; otherwise returns | |
945 | * SSH_MSG_NONE. This does not wait for data from the connection. | |
946 | * | |
947 | * SSH_MSG_DISCONNECT is handled specially here. Also, | |
948 | * SSH_MSG_IGNORE messages are skipped by this function and are never returned | |
949 | * to higher levels. | |
950 | */ | |
951 | ||
952 | static int | |
953 | packet_read_poll1(void) | |
954 | { | |
955 | u_int len, padded_len; | |
956 | u_char *cp, type; | |
957 | u_int checksum, stored_checksum; | |
958 | ||
959 | /* Check if input size is less than minimum packet size. */ | |
960 | if (buffer_len(&input) < 4 + 8) | |
961 | return SSH_MSG_NONE; | |
962 | /* Get length of incoming packet. */ | |
963 | cp = buffer_ptr(&input); | |
964 | len = GET_32BIT(cp); | |
965 | if (len < 1 + 2 + 2 || len > 256 * 1024) | |
966 | packet_disconnect("Bad packet length %u.", len); | |
967 | padded_len = (len + 8) & ~7; | |
968 | ||
969 | /* Check if the packet has been entirely received. */ | |
970 | if (buffer_len(&input) < 4 + padded_len) | |
971 | return SSH_MSG_NONE; | |
972 | ||
973 | /* The entire packet is in buffer. */ | |
974 | ||
975 | /* Consume packet length. */ | |
976 | buffer_consume(&input, 4); | |
977 | ||
978 | /* | |
979 | * Cryptographic attack detector for ssh | |
980 | * (C)1998 CORE-SDI, Buenos Aires Argentina | |
981 | * Ariel Futoransky(futo@core-sdi.com) | |
982 | */ | |
983 | if (!receive_context.plaintext && | |
984 | detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) | |
985 | packet_disconnect("crc32 compensation attack: network attack detected"); | |
986 | ||
987 | /* Decrypt data to incoming_packet. */ | |
988 | buffer_clear(&incoming_packet); | |
989 | cp = buffer_append_space(&incoming_packet, padded_len); | |
990 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); | |
991 | ||
992 | buffer_consume(&input, padded_len); | |
993 | ||
994 | #ifdef PACKET_DEBUG | |
995 | fprintf(stderr, "read_poll plain: "); | |
996 | buffer_dump(&incoming_packet); | |
997 | #endif | |
998 | ||
999 | /* Compute packet checksum. */ | |
1000 | checksum = ssh_crc32(buffer_ptr(&incoming_packet), | |
1001 | buffer_len(&incoming_packet) - 4); | |
1002 | ||
1003 | /* Skip padding. */ | |
1004 | buffer_consume(&incoming_packet, 8 - len % 8); | |
1005 | ||
1006 | /* Test check bytes. */ | |
1007 | if (len != buffer_len(&incoming_packet)) | |
1008 | packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", | |
1009 | len, buffer_len(&incoming_packet)); | |
1010 | ||
1011 | cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; | |
1012 | stored_checksum = GET_32BIT(cp); | |
1013 | if (checksum != stored_checksum) | |
1014 | packet_disconnect("Corrupted check bytes on input."); | |
1015 | buffer_consume_end(&incoming_packet, 4); | |
1016 | ||
1017 | if (packet_compression) { | |
1018 | buffer_clear(&compression_buffer); | |
1019 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
1020 | buffer_clear(&incoming_packet); | |
1021 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
1022 | buffer_len(&compression_buffer)); | |
1023 | } | |
1024 | type = buffer_get_char(&incoming_packet); | |
1025 | if (type < SSH_MSG_MIN || type > SSH_MSG_MAX) | |
1026 | packet_disconnect("Invalid ssh1 packet type: %d", type); | |
1027 | return type; | |
1028 | } | |
1029 | ||
1030 | static int | |
1031 | packet_read_poll2(u_int32_t *seqnr_p) | |
1032 | { | |
1033 | static u_int packet_length = 0; | |
1034 | u_int padlen, need; | |
1035 | u_char *macbuf, *cp, type; | |
1036 | u_int maclen, block_size; | |
1037 | Enc *enc = NULL; | |
1038 | Mac *mac = NULL; | |
1039 | Comp *comp = NULL; | |
1040 | ||
1041 | if (newkeys[MODE_IN] != NULL) { | |
1042 | enc = &newkeys[MODE_IN]->enc; | |
1043 | mac = &newkeys[MODE_IN]->mac; | |
1044 | comp = &newkeys[MODE_IN]->comp; | |
1045 | } | |
1046 | maclen = mac && mac->enabled ? mac->mac_len : 0; | |
1047 | block_size = enc ? enc->block_size : 8; | |
1048 | ||
1049 | if (packet_length == 0) { | |
1050 | /* | |
1051 | * check if input size is less than the cipher block size, | |
1052 | * decrypt first block and extract length of incoming packet | |
1053 | */ | |
1054 | if (buffer_len(&input) < block_size) | |
1055 | return SSH_MSG_NONE; | |
1056 | buffer_clear(&incoming_packet); | |
1057 | cp = buffer_append_space(&incoming_packet, block_size); | |
1058 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), | |
1059 | block_size); | |
1060 | cp = buffer_ptr(&incoming_packet); | |
1061 | packet_length = GET_32BIT(cp); | |
1062 | if (packet_length < 1 + 4 || packet_length > 256 * 1024) { | |
1063 | #ifdef PACKET_DEBUG | |
1064 | buffer_dump(&incoming_packet); | |
1065 | #endif | |
1066 | packet_disconnect("Bad packet length %u.", packet_length); | |
1067 | } | |
1068 | DBG(debug("input: packet len %u", packet_length+4)); | |
1069 | buffer_consume(&input, block_size); | |
1070 | } | |
1071 | /* we have a partial packet of block_size bytes */ | |
1072 | need = 4 + packet_length - block_size; | |
1073 | DBG(debug("partial packet %d, need %d, maclen %d", block_size, | |
1074 | need, maclen)); | |
1075 | if (need % block_size != 0) | |
1076 | fatal("padding error: need %d block %d mod %d", | |
1077 | need, block_size, need % block_size); | |
1078 | /* | |
1079 | * check if the entire packet has been received and | |
1080 | * decrypt into incoming_packet | |
1081 | */ | |
1082 | if (buffer_len(&input) < need + maclen) | |
1083 | return SSH_MSG_NONE; | |
1084 | #ifdef PACKET_DEBUG | |
1085 | fprintf(stderr, "read_poll enc/full: "); | |
1086 | buffer_dump(&input); | |
1087 | #endif | |
1088 | cp = buffer_append_space(&incoming_packet, need); | |
1089 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); | |
1090 | buffer_consume(&input, need); | |
1091 | /* | |
1092 | * compute MAC over seqnr and packet, | |
1093 | * increment sequence number for incoming packet | |
1094 | */ | |
1095 | if (mac && mac->enabled) { | |
1096 | macbuf = mac_compute(mac, p_read.seqnr, | |
1097 | buffer_ptr(&incoming_packet), | |
1098 | buffer_len(&incoming_packet)); | |
1099 | if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) | |
1100 | packet_disconnect("Corrupted MAC on input."); | |
1101 | DBG(debug("MAC #%d ok", p_read.seqnr)); | |
1102 | buffer_consume(&input, mac->mac_len); | |
1103 | } | |
1104 | if (seqnr_p != NULL) | |
1105 | *seqnr_p = p_read.seqnr; | |
1106 | if (++p_read.seqnr == 0) | |
1107 | logit("incoming seqnr wraps around"); | |
1108 | if (++p_read.packets == 0) | |
1109 | if (!(datafellows & SSH_BUG_NOREKEY)) | |
1110 | fatal("XXX too many packets with same key"); | |
1111 | p_read.blocks += (packet_length + 4) / block_size; | |
1112 | ||
1113 | /* get padlen */ | |
1114 | cp = buffer_ptr(&incoming_packet); | |
1115 | padlen = cp[4]; | |
1116 | DBG(debug("input: padlen %d", padlen)); | |
1117 | if (padlen < 4) | |
1118 | packet_disconnect("Corrupted padlen %d on input.", padlen); | |
1119 | ||
1120 | /* skip packet size + padlen, discard padding */ | |
1121 | buffer_consume(&incoming_packet, 4 + 1); | |
1122 | buffer_consume_end(&incoming_packet, padlen); | |
1123 | ||
1124 | DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); | |
1125 | if (comp && comp->enabled) { | |
1126 | buffer_clear(&compression_buffer); | |
1127 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
1128 | buffer_clear(&incoming_packet); | |
1129 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
1130 | buffer_len(&compression_buffer)); | |
1131 | DBG(debug("input: len after de-compress %d", | |
1132 | buffer_len(&incoming_packet))); | |
1133 | } | |
1134 | /* | |
1135 | * get packet type, implies consume. | |
1136 | * return length of payload (without type field) | |
1137 | */ | |
1138 | type = buffer_get_char(&incoming_packet); | |
1139 | if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN) | |
1140 | packet_disconnect("Invalid ssh2 packet type: %d", type); | |
1141 | if (type == SSH2_MSG_NEWKEYS) | |
1142 | set_newkeys(MODE_IN); | |
1143 | else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side) | |
1144 | packet_enable_delayed_compress(); | |
1145 | #ifdef PACKET_DEBUG | |
1146 | fprintf(stderr, "read/plain[%d]:\r\n", type); | |
1147 | buffer_dump(&incoming_packet); | |
1148 | #endif | |
1149 | /* reset for next packet */ | |
1150 | packet_length = 0; | |
1151 | return type; | |
1152 | } | |
1153 | ||
1154 | int | |
1155 | packet_read_poll_seqnr(u_int32_t *seqnr_p) | |
1156 | { | |
1157 | u_int reason, seqnr; | |
1158 | u_char type; | |
1159 | char *msg; | |
1160 | ||
1161 | for (;;) { | |
1162 | if (compat20) { | |
1163 | type = packet_read_poll2(seqnr_p); | |
1164 | if (type) | |
1165 | DBG(debug("received packet type %d", type)); | |
1166 | switch (type) { | |
1167 | case SSH2_MSG_IGNORE: | |
1168 | break; | |
1169 | case SSH2_MSG_DEBUG: | |
1170 | packet_get_char(); | |
1171 | msg = packet_get_string(NULL); | |
1172 | debug("Remote: %.900s", msg); | |
1173 | xfree(msg); | |
1174 | msg = packet_get_string(NULL); | |
1175 | xfree(msg); | |
1176 | break; | |
1177 | case SSH2_MSG_DISCONNECT: | |
1178 | reason = packet_get_int(); | |
1179 | msg = packet_get_string(NULL); | |
1180 | logit("Received disconnect from %s: %u: %.400s", | |
1181 | get_remote_ipaddr(), reason, msg); | |
1182 | xfree(msg); | |
1183 | cleanup_exit(255); | |
1184 | break; | |
1185 | case SSH2_MSG_UNIMPLEMENTED: | |
1186 | seqnr = packet_get_int(); | |
1187 | debug("Received SSH2_MSG_UNIMPLEMENTED for %u", | |
1188 | seqnr); | |
1189 | break; | |
1190 | default: | |
1191 | return type; | |
1192 | break; | |
1193 | } | |
1194 | } else { | |
1195 | type = packet_read_poll1(); | |
1196 | switch (type) { | |
1197 | case SSH_MSG_IGNORE: | |
1198 | break; | |
1199 | case SSH_MSG_DEBUG: | |
1200 | msg = packet_get_string(NULL); | |
1201 | debug("Remote: %.900s", msg); | |
1202 | xfree(msg); | |
1203 | break; | |
1204 | case SSH_MSG_DISCONNECT: | |
1205 | msg = packet_get_string(NULL); | |
1206 | logit("Received disconnect from %s: %.400s", | |
1207 | get_remote_ipaddr(), msg); | |
1208 | cleanup_exit(255); | |
1209 | xfree(msg); | |
1210 | break; | |
1211 | default: | |
1212 | if (type) | |
1213 | DBG(debug("received packet type %d", type)); | |
1214 | return type; | |
1215 | break; | |
1216 | } | |
1217 | } | |
1218 | } | |
1219 | } | |
1220 | ||
1221 | int | |
1222 | packet_read_poll(void) | |
1223 | { | |
1224 | return packet_read_poll_seqnr(NULL); | |
1225 | } | |
1226 | ||
1227 | /* | |
1228 | * Buffers the given amount of input characters. This is intended to be used | |
1229 | * together with packet_read_poll. | |
1230 | */ | |
1231 | ||
1232 | void | |
1233 | packet_process_incoming(const char *buf, u_int len) | |
1234 | { | |
1235 | buffer_append(&input, buf, len); | |
1236 | } | |
1237 | ||
1238 | /* Returns a character from the packet. */ | |
1239 | ||
1240 | u_int | |
1241 | packet_get_char(void) | |
1242 | { | |
1243 | char ch; | |
1244 | ||
1245 | buffer_get(&incoming_packet, &ch, 1); | |
1246 | return (u_char) ch; | |
1247 | } | |
1248 | ||
1249 | /* Returns an integer from the packet data. */ | |
1250 | ||
1251 | u_int | |
1252 | packet_get_int(void) | |
1253 | { | |
1254 | return buffer_get_int(&incoming_packet); | |
1255 | } | |
1256 | ||
1257 | /* | |
1258 | * Returns an arbitrary precision integer from the packet data. The integer | |
1259 | * must have been initialized before this call. | |
1260 | */ | |
1261 | ||
1262 | void | |
1263 | packet_get_bignum(BIGNUM * value) | |
1264 | { | |
1265 | buffer_get_bignum(&incoming_packet, value); | |
1266 | } | |
1267 | ||
1268 | void | |
1269 | packet_get_bignum2(BIGNUM * value) | |
1270 | { | |
1271 | buffer_get_bignum2(&incoming_packet, value); | |
1272 | } | |
1273 | ||
1274 | void * | |
1275 | packet_get_raw(u_int *length_ptr) | |
1276 | { | |
1277 | u_int bytes = buffer_len(&incoming_packet); | |
1278 | ||
1279 | if (length_ptr != NULL) | |
1280 | *length_ptr = bytes; | |
1281 | return buffer_ptr(&incoming_packet); | |
1282 | } | |
1283 | ||
1284 | int | |
1285 | packet_remaining(void) | |
1286 | { | |
1287 | return buffer_len(&incoming_packet); | |
1288 | } | |
1289 | ||
1290 | /* | |
1291 | * Returns a string from the packet data. The string is allocated using | |
1292 | * xmalloc; it is the responsibility of the calling program to free it when | |
1293 | * no longer needed. The length_ptr argument may be NULL, or point to an | |
1294 | * integer into which the length of the string is stored. | |
1295 | */ | |
1296 | ||
1297 | void * | |
1298 | packet_get_string(u_int *length_ptr) | |
1299 | { | |
1300 | return buffer_get_string(&incoming_packet, length_ptr); | |
1301 | } | |
1302 | ||
1303 | /* | |
1304 | * Sends a diagnostic message from the server to the client. This message | |
1305 | * can be sent at any time (but not while constructing another message). The | |
1306 | * message is printed immediately, but only if the client is being executed | |
1307 | * in verbose mode. These messages are primarily intended to ease debugging | |
1308 | * authentication problems. The length of the formatted message must not | |
1309 | * exceed 1024 bytes. This will automatically call packet_write_wait. | |
1310 | */ | |
1311 | ||
1312 | void | |
1313 | packet_send_debug(const char *fmt,...) | |
1314 | { | |
1315 | char buf[1024]; | |
1316 | va_list args; | |
1317 | ||
1318 | if (compat20 && (datafellows & SSH_BUG_DEBUG)) | |
1319 | return; | |
1320 | ||
1321 | va_start(args, fmt); | |
1322 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1323 | va_end(args); | |
1324 | ||
1325 | if (compat20) { | |
1326 | packet_start(SSH2_MSG_DEBUG); | |
1327 | packet_put_char(0); /* bool: always display */ | |
1328 | packet_put_cstring(buf); | |
1329 | packet_put_cstring(""); | |
1330 | } else { | |
1331 | packet_start(SSH_MSG_DEBUG); | |
1332 | packet_put_cstring(buf); | |
1333 | } | |
1334 | packet_send(); | |
1335 | packet_write_wait(); | |
1336 | } | |
1337 | ||
1338 | /* | |
1339 | * Logs the error plus constructs and sends a disconnect packet, closes the | |
1340 | * connection, and exits. This function never returns. The error message | |
1341 | * should not contain a newline. The length of the formatted message must | |
1342 | * not exceed 1024 bytes. | |
1343 | */ | |
1344 | ||
1345 | void | |
1346 | packet_disconnect(const char *fmt,...) | |
1347 | { | |
1348 | char buf[1024]; | |
1349 | va_list args; | |
1350 | static int disconnecting = 0; | |
1351 | ||
1352 | if (disconnecting) /* Guard against recursive invocations. */ | |
1353 | fatal("packet_disconnect called recursively."); | |
1354 | disconnecting = 1; | |
1355 | ||
1356 | /* | |
1357 | * Format the message. Note that the caller must make sure the | |
1358 | * message is of limited size. | |
1359 | */ | |
1360 | va_start(args, fmt); | |
1361 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1362 | va_end(args); | |
1363 | ||
1364 | /* Display the error locally */ | |
1365 | logit("Disconnecting: %.100s", buf); | |
1366 | ||
1367 | /* Send the disconnect message to the other side, and wait for it to get sent. */ | |
1368 | if (compat20) { | |
1369 | packet_start(SSH2_MSG_DISCONNECT); | |
1370 | packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); | |
1371 | packet_put_cstring(buf); | |
1372 | packet_put_cstring(""); | |
1373 | } else { | |
1374 | packet_start(SSH_MSG_DISCONNECT); | |
1375 | packet_put_cstring(buf); | |
1376 | } | |
1377 | packet_send(); | |
1378 | packet_write_wait(); | |
1379 | ||
1380 | /* Stop listening for connections. */ | |
1381 | channel_close_all(); | |
1382 | ||
1383 | /* Close the connection. */ | |
1384 | packet_close(); | |
1385 | cleanup_exit(255); | |
1386 | } | |
1387 | ||
1388 | /* Checks if there is any buffered output, and tries to write some of the output. */ | |
1389 | ||
1390 | void | |
1391 | packet_write_poll(void) | |
1392 | { | |
1393 | int len = buffer_len(&output); | |
1394 | ||
1395 | if (len > 0) { | |
1396 | len = write(connection_out, buffer_ptr(&output), len); | |
1397 | if (len <= 0) { | |
1398 | if (errno == EAGAIN) | |
1399 | return; | |
1400 | else | |
1401 | fatal("Write failed: %.100s", strerror(errno)); | |
1402 | } | |
1403 | buffer_consume(&output, len); | |
1404 | } | |
1405 | } | |
1406 | ||
1407 | /* | |
1408 | * Calls packet_write_poll repeatedly until all pending output data has been | |
1409 | * written. | |
1410 | */ | |
1411 | ||
1412 | void | |
1413 | packet_write_wait(void) | |
1414 | { | |
1415 | fd_set *setp; | |
1416 | ||
1417 | setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * | |
1418 | sizeof(fd_mask)); | |
1419 | packet_write_poll(); | |
1420 | while (packet_have_data_to_write()) { | |
1421 | memset(setp, 0, howmany(connection_out + 1, NFDBITS) * | |
1422 | sizeof(fd_mask)); | |
1423 | FD_SET(connection_out, setp); | |
1424 | while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && | |
1425 | (errno == EAGAIN || errno == EINTR)) | |
1426 | ; | |
1427 | packet_write_poll(); | |
1428 | } | |
1429 | xfree(setp); | |
1430 | } | |
1431 | ||
1432 | /* Returns true if there is buffered data to write to the connection. */ | |
1433 | ||
1434 | int | |
1435 | packet_have_data_to_write(void) | |
1436 | { | |
1437 | return buffer_len(&output) != 0; | |
1438 | } | |
1439 | ||
1440 | /* Returns true if there is not too much data to write to the connection. */ | |
1441 | ||
1442 | int | |
1443 | packet_not_very_much_data_to_write(void) | |
1444 | { | |
1445 | if (interactive_mode) | |
1446 | return buffer_len(&output) < 16384; | |
1447 | else | |
1448 | return buffer_len(&output) < 128 * 1024; | |
1449 | } | |
1450 | ||
1451 | ||
1452 | static void | |
1453 | packet_set_tos(int interactive) | |
1454 | { | |
1455 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) | |
1456 | int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; | |
1457 | ||
1458 | if (!packet_connection_is_on_socket() || | |
1459 | !packet_connection_is_ipv4()) | |
1460 | return; | |
1461 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, | |
1462 | sizeof(tos)) < 0) | |
1463 | error("setsockopt IP_TOS %d: %.100s:", | |
1464 | tos, strerror(errno)); | |
1465 | #endif | |
1466 | } | |
1467 | ||
1468 | /* Informs that the current session is interactive. Sets IP flags for that. */ | |
1469 | ||
1470 | void | |
1471 | packet_set_interactive(int interactive) | |
1472 | { | |
1473 | static int called = 0; | |
1474 | ||
1475 | if (called) | |
1476 | return; | |
1477 | called = 1; | |
1478 | ||
1479 | /* Record that we are in interactive mode. */ | |
1480 | interactive_mode = interactive; | |
1481 | ||
1482 | /* Only set socket options if using a socket. */ | |
1483 | if (!packet_connection_is_on_socket()) | |
1484 | return; | |
1485 | if (interactive) | |
1486 | set_nodelay(connection_in); | |
1487 | packet_set_tos(interactive); | |
1488 | } | |
1489 | ||
1490 | /* Returns true if the current connection is interactive. */ | |
1491 | ||
1492 | int | |
1493 | packet_is_interactive(void) | |
1494 | { | |
1495 | return interactive_mode; | |
1496 | } | |
1497 | ||
1498 | int | |
1499 | packet_set_maxsize(u_int s) | |
1500 | { | |
1501 | static int called = 0; | |
1502 | ||
1503 | if (called) { | |
1504 | logit("packet_set_maxsize: called twice: old %d new %d", | |
1505 | max_packet_size, s); | |
1506 | return -1; | |
1507 | } | |
1508 | if (s < 4 * 1024 || s > 1024 * 1024) { | |
1509 | logit("packet_set_maxsize: bad size %d", s); | |
1510 | return -1; | |
1511 | } | |
1512 | called = 1; | |
1513 | debug("packet_set_maxsize: setting to %d", s); | |
1514 | max_packet_size = s; | |
1515 | return s; | |
1516 | } | |
1517 | ||
1518 | /* roundup current message to pad bytes */ | |
1519 | void | |
1520 | packet_add_padding(u_char pad) | |
1521 | { | |
1522 | extra_pad = pad; | |
1523 | } | |
1524 | ||
1525 | /* | |
1526 | * 9.2. Ignored Data Message | |
1527 | * | |
1528 | * byte SSH_MSG_IGNORE | |
1529 | * string data | |
1530 | * | |
1531 | * All implementations MUST understand (and ignore) this message at any | |
1532 | * time (after receiving the protocol version). No implementation is | |
1533 | * required to send them. This message can be used as an additional | |
1534 | * protection measure against advanced traffic analysis techniques. | |
1535 | */ | |
1536 | void | |
1537 | packet_send_ignore(int nbytes) | |
1538 | { | |
1539 | u_int32_t rnd = 0; | |
1540 | int i; | |
1541 | ||
1542 | packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); | |
1543 | packet_put_int(nbytes); | |
1544 | for (i = 0; i < nbytes; i++) { | |
1545 | if (i % 4 == 0) | |
1546 | rnd = arc4random(); | |
1547 | packet_put_char(rnd & 0xff); | |
1548 | rnd >>= 8; | |
1549 | } | |
1550 | } | |
1551 | ||
1552 | #define MAX_PACKETS (1U<<31) | |
1553 | int | |
1554 | packet_need_rekeying(void) | |
1555 | { | |
1556 | if (datafellows & SSH_BUG_NOREKEY) | |
1557 | return 0; | |
1558 | return | |
1559 | (p_send.packets > MAX_PACKETS) || | |
1560 | (p_read.packets > MAX_PACKETS) || | |
1561 | (max_blocks_out && (p_send.blocks > max_blocks_out)) || | |
1562 | (max_blocks_in && (p_read.blocks > max_blocks_in)); | |
1563 | } | |
1564 | ||
1565 | void | |
1566 | packet_set_rekey_limit(u_int32_t bytes) | |
1567 | { | |
1568 | rekey_limit = bytes; | |
1569 | } | |
1570 | ||
1571 | void | |
1572 | packet_set_server(void) | |
1573 | { | |
1574 | server_side = 1; | |
1575 | } | |
1576 | ||
1577 | void | |
1578 | packet_set_authenticated(void) | |
1579 | { | |
1580 | after_authentication = 1; | |
1581 | } |