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1 | /* $OpenBSD: packet.c,v 1.160 2009/02/13 11:50:21 markus Exp $ */ | |
2 | /* | |
3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | * All rights reserved | |
6 | * This file contains code implementing the packet protocol and communication | |
7 | * with the other side. This same code is used both on client and server side. | |
8 | * | |
9 | * As far as I am concerned, the code I have written for this software | |
10 | * can be used freely for any purpose. Any derived versions of this | |
11 | * software must be clearly marked as such, and if the derived work is | |
12 | * incompatible with the protocol description in the RFC file, it must be | |
13 | * called by a name other than "ssh" or "Secure Shell". | |
14 | * | |
15 | * | |
16 | * SSH2 packet format added by Markus Friedl. | |
17 | * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. | |
18 | * | |
19 | * Redistribution and use in source and binary forms, with or without | |
20 | * modification, are permitted provided that the following conditions | |
21 | * are met: | |
22 | * 1. Redistributions of source code must retain the above copyright | |
23 | * notice, this list of conditions and the following disclaimer. | |
24 | * 2. Redistributions in binary form must reproduce the above copyright | |
25 | * notice, this list of conditions and the following disclaimer in the | |
26 | * documentation and/or other materials provided with the distribution. | |
27 | * | |
28 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
29 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
30 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
31 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
33 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
34 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
35 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
36 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
37 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
38 | */ | |
39 | ||
40 | #include "includes.h" | |
41 | ||
42 | #include <sys/types.h> | |
43 | #include "openbsd-compat/sys-queue.h" | |
44 | #include <sys/param.h> | |
45 | #include <sys/socket.h> | |
46 | #ifdef HAVE_SYS_TIME_H | |
47 | # include <sys/time.h> | |
48 | #endif | |
49 | ||
50 | #include <netinet/in.h> | |
51 | #include <netinet/ip.h> | |
52 | #include <arpa/inet.h> | |
53 | ||
54 | #include <errno.h> | |
55 | #include <stdarg.h> | |
56 | #include <stdio.h> | |
57 | #include <stdlib.h> | |
58 | #include <string.h> | |
59 | #include <unistd.h> | |
60 | #include <signal.h> | |
61 | ||
62 | #include "xmalloc.h" | |
63 | #include "buffer.h" | |
64 | #include "packet.h" | |
65 | #include "crc32.h" | |
66 | #include "compress.h" | |
67 | #include "deattack.h" | |
68 | #include "channels.h" | |
69 | #include "compat.h" | |
70 | #include "ssh1.h" | |
71 | #include "ssh2.h" | |
72 | #include "cipher.h" | |
73 | #include "key.h" | |
74 | #include "kex.h" | |
75 | #include "mac.h" | |
76 | #include "log.h" | |
77 | #include "canohost.h" | |
78 | #include "misc.h" | |
79 | #include "ssh.h" | |
80 | ||
81 | #ifdef PACKET_DEBUG | |
82 | #define DBG(x) x | |
83 | #else | |
84 | #define DBG(x) | |
85 | #endif | |
86 | ||
87 | #define PACKET_MAX_SIZE (256 * 1024) | |
88 | ||
89 | /* | |
90 | * This variable contains the file descriptors used for communicating with | |
91 | * the other side. connection_in is used for reading; connection_out for | |
92 | * writing. These can be the same descriptor, in which case it is assumed to | |
93 | * be a socket. | |
94 | */ | |
95 | static int connection_in = -1; | |
96 | static int connection_out = -1; | |
97 | ||
98 | /* Protocol flags for the remote side. */ | |
99 | static u_int remote_protocol_flags = 0; | |
100 | ||
101 | /* Encryption context for receiving data. This is only used for decryption. */ | |
102 | static CipherContext receive_context; | |
103 | ||
104 | /* Encryption context for sending data. This is only used for encryption. */ | |
105 | static CipherContext send_context; | |
106 | ||
107 | /* Buffer for raw input data from the socket. */ | |
108 | Buffer input; | |
109 | ||
110 | /* Buffer for raw output data going to the socket. */ | |
111 | Buffer output; | |
112 | ||
113 | /* Buffer for the partial outgoing packet being constructed. */ | |
114 | static Buffer outgoing_packet; | |
115 | ||
116 | /* Buffer for the incoming packet currently being processed. */ | |
117 | static Buffer incoming_packet; | |
118 | ||
119 | /* Scratch buffer for packet compression/decompression. */ | |
120 | static Buffer compression_buffer; | |
121 | static int compression_buffer_ready = 0; | |
122 | ||
123 | /* Flag indicating whether packet compression/decompression is enabled. */ | |
124 | static int packet_compression = 0; | |
125 | ||
126 | /* default maximum packet size */ | |
127 | u_int max_packet_size = 32768; | |
128 | ||
129 | /* Flag indicating whether this module has been initialized. */ | |
130 | static int initialized = 0; | |
131 | ||
132 | /* Set to true if the connection is interactive. */ | |
133 | static int interactive_mode = 0; | |
134 | ||
135 | /* Set to true if we are the server side. */ | |
136 | static int server_side = 0; | |
137 | ||
138 | /* Set to true if we are authenticated. */ | |
139 | static int after_authentication = 0; | |
140 | ||
141 | int keep_alive_timeouts = 0; | |
142 | ||
143 | /* Set to the maximum time that we will wait to send or receive a packet */ | |
144 | static int packet_timeout_ms = -1; | |
145 | ||
146 | /* Session key information for Encryption and MAC */ | |
147 | Newkeys *newkeys[MODE_MAX]; | |
148 | static struct packet_state { | |
149 | u_int32_t seqnr; | |
150 | u_int32_t packets; | |
151 | u_int64_t blocks; | |
152 | u_int64_t bytes; | |
153 | } p_read, p_send; | |
154 | ||
155 | static u_int64_t max_blocks_in, max_blocks_out; | |
156 | static u_int32_t rekey_limit; | |
157 | ||
158 | /* Session key for protocol v1 */ | |
159 | static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; | |
160 | static u_int ssh1_keylen; | |
161 | ||
162 | /* roundup current message to extra_pad bytes */ | |
163 | static u_char extra_pad = 0; | |
164 | ||
165 | /* XXX discard incoming data after MAC error */ | |
166 | static u_int packet_discard = 0; | |
167 | static Mac *packet_discard_mac = NULL; | |
168 | ||
169 | struct packet { | |
170 | TAILQ_ENTRY(packet) next; | |
171 | u_char type; | |
172 | Buffer payload; | |
173 | }; | |
174 | TAILQ_HEAD(, packet) outgoing; | |
175 | ||
176 | /* | |
177 | * Sets the descriptors used for communication. Disables encryption until | |
178 | * packet_set_encryption_key is called. | |
179 | */ | |
180 | void | |
181 | packet_set_connection(int fd_in, int fd_out) | |
182 | { | |
183 | Cipher *none = cipher_by_name("none"); | |
184 | ||
185 | if (none == NULL) | |
186 | fatal("packet_set_connection: cannot load cipher 'none'"); | |
187 | connection_in = fd_in; | |
188 | connection_out = fd_out; | |
189 | cipher_init(&send_context, none, (const u_char *)"", | |
190 | 0, NULL, 0, CIPHER_ENCRYPT); | |
191 | cipher_init(&receive_context, none, (const u_char *)"", | |
192 | 0, NULL, 0, CIPHER_DECRYPT); | |
193 | newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; | |
194 | if (!initialized) { | |
195 | initialized = 1; | |
196 | buffer_init(&input); | |
197 | buffer_init(&output); | |
198 | buffer_init(&outgoing_packet); | |
199 | buffer_init(&incoming_packet); | |
200 | TAILQ_INIT(&outgoing); | |
201 | p_send.packets = p_read.packets = 0; | |
202 | } | |
203 | } | |
204 | ||
205 | void | |
206 | packet_set_timeout(int timeout, int count) | |
207 | { | |
208 | if (timeout == 0 || count == 0) { | |
209 | packet_timeout_ms = -1; | |
210 | return; | |
211 | } | |
212 | if ((INT_MAX / 1000) / count < timeout) | |
213 | packet_timeout_ms = INT_MAX; | |
214 | else | |
215 | packet_timeout_ms = timeout * count * 1000; | |
216 | } | |
217 | ||
218 | static void | |
219 | packet_stop_discard(void) | |
220 | { | |
221 | if (packet_discard_mac) { | |
222 | char buf[1024]; | |
223 | ||
224 | memset(buf, 'a', sizeof(buf)); | |
225 | while (buffer_len(&incoming_packet) < PACKET_MAX_SIZE) | |
226 | buffer_append(&incoming_packet, buf, sizeof(buf)); | |
227 | (void) mac_compute(packet_discard_mac, | |
228 | p_read.seqnr, | |
229 | buffer_ptr(&incoming_packet), | |
230 | PACKET_MAX_SIZE); | |
231 | } | |
232 | logit("Finished discarding for %.200s", get_remote_ipaddr()); | |
233 | cleanup_exit(255); | |
234 | } | |
235 | ||
236 | static void | |
237 | packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard) | |
238 | { | |
239 | if (enc == NULL || !cipher_is_cbc(enc->cipher)) | |
240 | packet_disconnect("Packet corrupt"); | |
241 | if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled) | |
242 | packet_discard_mac = mac; | |
243 | if (buffer_len(&input) >= discard) | |
244 | packet_stop_discard(); | |
245 | packet_discard = discard - buffer_len(&input); | |
246 | } | |
247 | ||
248 | /* Returns 1 if remote host is connected via socket, 0 if not. */ | |
249 | ||
250 | int | |
251 | packet_connection_is_on_socket(void) | |
252 | { | |
253 | struct sockaddr_storage from, to; | |
254 | socklen_t fromlen, tolen; | |
255 | ||
256 | /* filedescriptors in and out are the same, so it's a socket */ | |
257 | if (connection_in == connection_out) | |
258 | return 1; | |
259 | fromlen = sizeof(from); | |
260 | memset(&from, 0, sizeof(from)); | |
261 | if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) | |
262 | return 0; | |
263 | tolen = sizeof(to); | |
264 | memset(&to, 0, sizeof(to)); | |
265 | if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
266 | return 0; | |
267 | if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) | |
268 | return 0; | |
269 | if (from.ss_family != AF_INET && from.ss_family != AF_INET6) | |
270 | return 0; | |
271 | return 1; | |
272 | } | |
273 | ||
274 | /* | |
275 | * Exports an IV from the CipherContext required to export the key | |
276 | * state back from the unprivileged child to the privileged parent | |
277 | * process. | |
278 | */ | |
279 | ||
280 | void | |
281 | packet_get_keyiv(int mode, u_char *iv, u_int len) | |
282 | { | |
283 | CipherContext *cc; | |
284 | ||
285 | if (mode == MODE_OUT) | |
286 | cc = &send_context; | |
287 | else | |
288 | cc = &receive_context; | |
289 | ||
290 | cipher_get_keyiv(cc, iv, len); | |
291 | } | |
292 | ||
293 | int | |
294 | packet_get_keycontext(int mode, u_char *dat) | |
295 | { | |
296 | CipherContext *cc; | |
297 | ||
298 | if (mode == MODE_OUT) | |
299 | cc = &send_context; | |
300 | else | |
301 | cc = &receive_context; | |
302 | ||
303 | return (cipher_get_keycontext(cc, dat)); | |
304 | } | |
305 | ||
306 | void | |
307 | packet_set_keycontext(int mode, u_char *dat) | |
308 | { | |
309 | CipherContext *cc; | |
310 | ||
311 | if (mode == MODE_OUT) | |
312 | cc = &send_context; | |
313 | else | |
314 | cc = &receive_context; | |
315 | ||
316 | cipher_set_keycontext(cc, dat); | |
317 | } | |
318 | ||
319 | int | |
320 | packet_get_keyiv_len(int mode) | |
321 | { | |
322 | CipherContext *cc; | |
323 | ||
324 | if (mode == MODE_OUT) | |
325 | cc = &send_context; | |
326 | else | |
327 | cc = &receive_context; | |
328 | ||
329 | return (cipher_get_keyiv_len(cc)); | |
330 | } | |
331 | ||
332 | void | |
333 | packet_set_iv(int mode, u_char *dat) | |
334 | { | |
335 | CipherContext *cc; | |
336 | ||
337 | if (mode == MODE_OUT) | |
338 | cc = &send_context; | |
339 | else | |
340 | cc = &receive_context; | |
341 | ||
342 | cipher_set_keyiv(cc, dat); | |
343 | } | |
344 | ||
345 | int | |
346 | packet_get_ssh1_cipher(void) | |
347 | { | |
348 | return (cipher_get_number(receive_context.cipher)); | |
349 | } | |
350 | ||
351 | void | |
352 | packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets, | |
353 | u_int64_t *bytes) | |
354 | { | |
355 | struct packet_state *state; | |
356 | ||
357 | state = (mode == MODE_IN) ? &p_read : &p_send; | |
358 | if (seqnr) | |
359 | *seqnr = state->seqnr; | |
360 | if (blocks) | |
361 | *blocks = state->blocks; | |
362 | if (packets) | |
363 | *packets = state->packets; | |
364 | if (bytes) | |
365 | *bytes = state->bytes; | |
366 | } | |
367 | ||
368 | void | |
369 | packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets, | |
370 | u_int64_t bytes) | |
371 | { | |
372 | struct packet_state *state; | |
373 | ||
374 | state = (mode == MODE_IN) ? &p_read : &p_send; | |
375 | state->seqnr = seqnr; | |
376 | state->blocks = blocks; | |
377 | state->packets = packets; | |
378 | state->bytes = bytes; | |
379 | } | |
380 | ||
381 | /* returns 1 if connection is via ipv4 */ | |
382 | ||
383 | int | |
384 | packet_connection_is_ipv4(void) | |
385 | { | |
386 | struct sockaddr_storage to; | |
387 | socklen_t tolen = sizeof(to); | |
388 | ||
389 | memset(&to, 0, sizeof(to)); | |
390 | if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
391 | return 0; | |
392 | if (to.ss_family == AF_INET) | |
393 | return 1; | |
394 | #ifdef IPV4_IN_IPV6 | |
395 | if (to.ss_family == AF_INET6 && | |
396 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) | |
397 | return 1; | |
398 | #endif | |
399 | return 0; | |
400 | } | |
401 | ||
402 | /* Sets the connection into non-blocking mode. */ | |
403 | ||
404 | void | |
405 | packet_set_nonblocking(void) | |
406 | { | |
407 | /* Set the socket into non-blocking mode. */ | |
408 | set_nonblock(connection_in); | |
409 | ||
410 | if (connection_out != connection_in) | |
411 | set_nonblock(connection_out); | |
412 | } | |
413 | ||
414 | /* Returns the socket used for reading. */ | |
415 | ||
416 | int | |
417 | packet_get_connection_in(void) | |
418 | { | |
419 | return connection_in; | |
420 | } | |
421 | ||
422 | /* Returns the descriptor used for writing. */ | |
423 | ||
424 | int | |
425 | packet_get_connection_out(void) | |
426 | { | |
427 | return connection_out; | |
428 | } | |
429 | ||
430 | /* Closes the connection and clears and frees internal data structures. */ | |
431 | ||
432 | void | |
433 | packet_close(void) | |
434 | { | |
435 | if (!initialized) | |
436 | return; | |
437 | initialized = 0; | |
438 | if (connection_in == connection_out) { | |
439 | shutdown(connection_out, SHUT_RDWR); | |
440 | close(connection_out); | |
441 | } else { | |
442 | close(connection_in); | |
443 | close(connection_out); | |
444 | } | |
445 | buffer_free(&input); | |
446 | buffer_free(&output); | |
447 | buffer_free(&outgoing_packet); | |
448 | buffer_free(&incoming_packet); | |
449 | if (compression_buffer_ready) { | |
450 | buffer_free(&compression_buffer); | |
451 | buffer_compress_uninit(); | |
452 | } | |
453 | cipher_cleanup(&send_context); | |
454 | cipher_cleanup(&receive_context); | |
455 | } | |
456 | ||
457 | /* Sets remote side protocol flags. */ | |
458 | ||
459 | void | |
460 | packet_set_protocol_flags(u_int protocol_flags) | |
461 | { | |
462 | remote_protocol_flags = protocol_flags; | |
463 | } | |
464 | ||
465 | /* Returns the remote protocol flags set earlier by the above function. */ | |
466 | ||
467 | u_int | |
468 | packet_get_protocol_flags(void) | |
469 | { | |
470 | return remote_protocol_flags; | |
471 | } | |
472 | ||
473 | /* | |
474 | * Starts packet compression from the next packet on in both directions. | |
475 | * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. | |
476 | */ | |
477 | ||
478 | static void | |
479 | packet_init_compression(void) | |
480 | { | |
481 | if (compression_buffer_ready == 1) | |
482 | return; | |
483 | compression_buffer_ready = 1; | |
484 | buffer_init(&compression_buffer); | |
485 | } | |
486 | ||
487 | void | |
488 | packet_start_compression(int level) | |
489 | { | |
490 | if (packet_compression && !compat20) | |
491 | fatal("Compression already enabled."); | |
492 | packet_compression = 1; | |
493 | packet_init_compression(); | |
494 | buffer_compress_init_send(level); | |
495 | buffer_compress_init_recv(); | |
496 | } | |
497 | ||
498 | /* | |
499 | * Causes any further packets to be encrypted using the given key. The same | |
500 | * key is used for both sending and reception. However, both directions are | |
501 | * encrypted independently of each other. | |
502 | */ | |
503 | ||
504 | void | |
505 | packet_set_encryption_key(const u_char *key, u_int keylen, | |
506 | int number) | |
507 | { | |
508 | Cipher *cipher = cipher_by_number(number); | |
509 | ||
510 | if (cipher == NULL) | |
511 | fatal("packet_set_encryption_key: unknown cipher number %d", number); | |
512 | if (keylen < 20) | |
513 | fatal("packet_set_encryption_key: keylen too small: %d", keylen); | |
514 | if (keylen > SSH_SESSION_KEY_LENGTH) | |
515 | fatal("packet_set_encryption_key: keylen too big: %d", keylen); | |
516 | memcpy(ssh1_key, key, keylen); | |
517 | ssh1_keylen = keylen; | |
518 | cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); | |
519 | cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); | |
520 | } | |
521 | ||
522 | u_int | |
523 | packet_get_encryption_key(u_char *key) | |
524 | { | |
525 | if (key == NULL) | |
526 | return (ssh1_keylen); | |
527 | memcpy(key, ssh1_key, ssh1_keylen); | |
528 | return (ssh1_keylen); | |
529 | } | |
530 | ||
531 | /* Start constructing a packet to send. */ | |
532 | void | |
533 | packet_start(u_char type) | |
534 | { | |
535 | u_char buf[9]; | |
536 | int len; | |
537 | ||
538 | DBG(debug("packet_start[%d]", type)); | |
539 | len = compat20 ? 6 : 9; | |
540 | memset(buf, 0, len - 1); | |
541 | buf[len - 1] = type; | |
542 | buffer_clear(&outgoing_packet); | |
543 | buffer_append(&outgoing_packet, buf, len); | |
544 | } | |
545 | ||
546 | /* Append payload. */ | |
547 | void | |
548 | packet_put_char(int value) | |
549 | { | |
550 | char ch = value; | |
551 | ||
552 | buffer_append(&outgoing_packet, &ch, 1); | |
553 | } | |
554 | ||
555 | void | |
556 | packet_put_int(u_int value) | |
557 | { | |
558 | buffer_put_int(&outgoing_packet, value); | |
559 | } | |
560 | ||
561 | void | |
562 | packet_put_string(const void *buf, u_int len) | |
563 | { | |
564 | buffer_put_string(&outgoing_packet, buf, len); | |
565 | } | |
566 | ||
567 | void | |
568 | packet_put_cstring(const char *str) | |
569 | { | |
570 | buffer_put_cstring(&outgoing_packet, str); | |
571 | } | |
572 | ||
573 | void | |
574 | packet_put_raw(const void *buf, u_int len) | |
575 | { | |
576 | buffer_append(&outgoing_packet, buf, len); | |
577 | } | |
578 | ||
579 | void | |
580 | packet_put_bignum(BIGNUM * value) | |
581 | { | |
582 | buffer_put_bignum(&outgoing_packet, value); | |
583 | } | |
584 | ||
585 | void | |
586 | packet_put_bignum2(BIGNUM * value) | |
587 | { | |
588 | buffer_put_bignum2(&outgoing_packet, value); | |
589 | } | |
590 | ||
591 | /* | |
592 | * Finalizes and sends the packet. If the encryption key has been set, | |
593 | * encrypts the packet before sending. | |
594 | */ | |
595 | ||
596 | static void | |
597 | packet_send1(void) | |
598 | { | |
599 | u_char buf[8], *cp; | |
600 | int i, padding, len; | |
601 | u_int checksum; | |
602 | u_int32_t rnd = 0; | |
603 | ||
604 | /* | |
605 | * If using packet compression, compress the payload of the outgoing | |
606 | * packet. | |
607 | */ | |
608 | if (packet_compression) { | |
609 | buffer_clear(&compression_buffer); | |
610 | /* Skip padding. */ | |
611 | buffer_consume(&outgoing_packet, 8); | |
612 | /* padding */ | |
613 | buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); | |
614 | buffer_compress(&outgoing_packet, &compression_buffer); | |
615 | buffer_clear(&outgoing_packet); | |
616 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
617 | buffer_len(&compression_buffer)); | |
618 | } | |
619 | /* Compute packet length without padding (add checksum, remove padding). */ | |
620 | len = buffer_len(&outgoing_packet) + 4 - 8; | |
621 | ||
622 | /* Insert padding. Initialized to zero in packet_start1() */ | |
623 | padding = 8 - len % 8; | |
624 | if (!send_context.plaintext) { | |
625 | cp = buffer_ptr(&outgoing_packet); | |
626 | for (i = 0; i < padding; i++) { | |
627 | if (i % 4 == 0) | |
628 | rnd = arc4random(); | |
629 | cp[7 - i] = rnd & 0xff; | |
630 | rnd >>= 8; | |
631 | } | |
632 | } | |
633 | buffer_consume(&outgoing_packet, 8 - padding); | |
634 | ||
635 | /* Add check bytes. */ | |
636 | checksum = ssh_crc32(buffer_ptr(&outgoing_packet), | |
637 | buffer_len(&outgoing_packet)); | |
638 | put_u32(buf, checksum); | |
639 | buffer_append(&outgoing_packet, buf, 4); | |
640 | ||
641 | #ifdef PACKET_DEBUG | |
642 | fprintf(stderr, "packet_send plain: "); | |
643 | buffer_dump(&outgoing_packet); | |
644 | #endif | |
645 | ||
646 | /* Append to output. */ | |
647 | put_u32(buf, len); | |
648 | buffer_append(&output, buf, 4); | |
649 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); | |
650 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
651 | buffer_len(&outgoing_packet)); | |
652 | ||
653 | #ifdef PACKET_DEBUG | |
654 | fprintf(stderr, "encrypted: "); | |
655 | buffer_dump(&output); | |
656 | #endif | |
657 | p_send.packets++; | |
658 | p_send.bytes += len + buffer_len(&outgoing_packet); | |
659 | buffer_clear(&outgoing_packet); | |
660 | ||
661 | /* | |
662 | * Note that the packet is now only buffered in output. It won't be | |
663 | * actually sent until packet_write_wait or packet_write_poll is | |
664 | * called. | |
665 | */ | |
666 | } | |
667 | ||
668 | void | |
669 | set_newkeys(int mode) | |
670 | { | |
671 | Enc *enc; | |
672 | Mac *mac; | |
673 | Comp *comp; | |
674 | CipherContext *cc; | |
675 | u_int64_t *max_blocks; | |
676 | int crypt_type; | |
677 | ||
678 | debug2("set_newkeys: mode %d", mode); | |
679 | ||
680 | if (mode == MODE_OUT) { | |
681 | cc = &send_context; | |
682 | crypt_type = CIPHER_ENCRYPT; | |
683 | p_send.packets = p_send.blocks = 0; | |
684 | max_blocks = &max_blocks_out; | |
685 | } else { | |
686 | cc = &receive_context; | |
687 | crypt_type = CIPHER_DECRYPT; | |
688 | p_read.packets = p_read.blocks = 0; | |
689 | max_blocks = &max_blocks_in; | |
690 | } | |
691 | if (newkeys[mode] != NULL) { | |
692 | debug("set_newkeys: rekeying"); | |
693 | cipher_cleanup(cc); | |
694 | enc = &newkeys[mode]->enc; | |
695 | mac = &newkeys[mode]->mac; | |
696 | comp = &newkeys[mode]->comp; | |
697 | mac_clear(mac); | |
698 | xfree(enc->name); | |
699 | xfree(enc->iv); | |
700 | xfree(enc->key); | |
701 | xfree(mac->name); | |
702 | xfree(mac->key); | |
703 | xfree(comp->name); | |
704 | xfree(newkeys[mode]); | |
705 | } | |
706 | newkeys[mode] = kex_get_newkeys(mode); | |
707 | if (newkeys[mode] == NULL) | |
708 | fatal("newkeys: no keys for mode %d", mode); | |
709 | enc = &newkeys[mode]->enc; | |
710 | mac = &newkeys[mode]->mac; | |
711 | comp = &newkeys[mode]->comp; | |
712 | if (mac_init(mac) == 0) | |
713 | mac->enabled = 1; | |
714 | DBG(debug("cipher_init_context: %d", mode)); | |
715 | cipher_init(cc, enc->cipher, enc->key, enc->key_len, | |
716 | enc->iv, enc->block_size, crypt_type); | |
717 | /* Deleting the keys does not gain extra security */ | |
718 | /* memset(enc->iv, 0, enc->block_size); | |
719 | memset(enc->key, 0, enc->key_len); | |
720 | memset(mac->key, 0, mac->key_len); */ | |
721 | if ((comp->type == COMP_ZLIB || | |
722 | (comp->type == COMP_DELAYED && after_authentication)) && | |
723 | comp->enabled == 0) { | |
724 | packet_init_compression(); | |
725 | if (mode == MODE_OUT) | |
726 | buffer_compress_init_send(6); | |
727 | else | |
728 | buffer_compress_init_recv(); | |
729 | comp->enabled = 1; | |
730 | } | |
731 | /* | |
732 | * The 2^(blocksize*2) limit is too expensive for 3DES, | |
733 | * blowfish, etc, so enforce a 1GB limit for small blocksizes. | |
734 | */ | |
735 | if (enc->block_size >= 16) | |
736 | *max_blocks = (u_int64_t)1 << (enc->block_size*2); | |
737 | else | |
738 | *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; | |
739 | if (rekey_limit) | |
740 | *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); | |
741 | } | |
742 | ||
743 | /* | |
744 | * Delayed compression for SSH2 is enabled after authentication: | |
745 | * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent, | |
746 | * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received. | |
747 | */ | |
748 | static void | |
749 | packet_enable_delayed_compress(void) | |
750 | { | |
751 | Comp *comp = NULL; | |
752 | int mode; | |
753 | ||
754 | /* | |
755 | * Remember that we are past the authentication step, so rekeying | |
756 | * with COMP_DELAYED will turn on compression immediately. | |
757 | */ | |
758 | after_authentication = 1; | |
759 | for (mode = 0; mode < MODE_MAX; mode++) { | |
760 | /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */ | |
761 | if (newkeys[mode] == NULL) | |
762 | continue; | |
763 | comp = &newkeys[mode]->comp; | |
764 | if (comp && !comp->enabled && comp->type == COMP_DELAYED) { | |
765 | packet_init_compression(); | |
766 | if (mode == MODE_OUT) | |
767 | buffer_compress_init_send(6); | |
768 | else | |
769 | buffer_compress_init_recv(); | |
770 | comp->enabled = 1; | |
771 | } | |
772 | } | |
773 | } | |
774 | ||
775 | /* | |
776 | * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) | |
777 | */ | |
778 | static void | |
779 | packet_send2_wrapped(void) | |
780 | { | |
781 | u_char type, *cp, *macbuf = NULL; | |
782 | u_char padlen, pad; | |
783 | u_int packet_length = 0; | |
784 | u_int i, len; | |
785 | u_int32_t rnd = 0; | |
786 | Enc *enc = NULL; | |
787 | Mac *mac = NULL; | |
788 | Comp *comp = NULL; | |
789 | int block_size; | |
790 | ||
791 | if (newkeys[MODE_OUT] != NULL) { | |
792 | enc = &newkeys[MODE_OUT]->enc; | |
793 | mac = &newkeys[MODE_OUT]->mac; | |
794 | comp = &newkeys[MODE_OUT]->comp; | |
795 | } | |
796 | block_size = enc ? enc->block_size : 8; | |
797 | ||
798 | cp = buffer_ptr(&outgoing_packet); | |
799 | type = cp[5]; | |
800 | ||
801 | #ifdef PACKET_DEBUG | |
802 | fprintf(stderr, "plain: "); | |
803 | buffer_dump(&outgoing_packet); | |
804 | #endif | |
805 | ||
806 | if (comp && comp->enabled) { | |
807 | len = buffer_len(&outgoing_packet); | |
808 | /* skip header, compress only payload */ | |
809 | buffer_consume(&outgoing_packet, 5); | |
810 | buffer_clear(&compression_buffer); | |
811 | buffer_compress(&outgoing_packet, &compression_buffer); | |
812 | buffer_clear(&outgoing_packet); | |
813 | buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); | |
814 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
815 | buffer_len(&compression_buffer)); | |
816 | DBG(debug("compression: raw %d compressed %d", len, | |
817 | buffer_len(&outgoing_packet))); | |
818 | } | |
819 | ||
820 | /* sizeof (packet_len + pad_len + payload) */ | |
821 | len = buffer_len(&outgoing_packet); | |
822 | ||
823 | /* | |
824 | * calc size of padding, alloc space, get random data, | |
825 | * minimum padding is 4 bytes | |
826 | */ | |
827 | padlen = block_size - (len % block_size); | |
828 | if (padlen < 4) | |
829 | padlen += block_size; | |
830 | if (extra_pad) { | |
831 | /* will wrap if extra_pad+padlen > 255 */ | |
832 | extra_pad = roundup(extra_pad, block_size); | |
833 | pad = extra_pad - ((len + padlen) % extra_pad); | |
834 | debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", | |
835 | pad, len, padlen, extra_pad); | |
836 | padlen += pad; | |
837 | extra_pad = 0; | |
838 | } | |
839 | cp = buffer_append_space(&outgoing_packet, padlen); | |
840 | if (enc && !send_context.plaintext) { | |
841 | /* random padding */ | |
842 | for (i = 0; i < padlen; i++) { | |
843 | if (i % 4 == 0) | |
844 | rnd = arc4random(); | |
845 | cp[i] = rnd & 0xff; | |
846 | rnd >>= 8; | |
847 | } | |
848 | } else { | |
849 | /* clear padding */ | |
850 | memset(cp, 0, padlen); | |
851 | } | |
852 | /* packet_length includes payload, padding and padding length field */ | |
853 | packet_length = buffer_len(&outgoing_packet) - 4; | |
854 | cp = buffer_ptr(&outgoing_packet); | |
855 | put_u32(cp, packet_length); | |
856 | cp[4] = padlen; | |
857 | DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); | |
858 | ||
859 | /* compute MAC over seqnr and packet(length fields, payload, padding) */ | |
860 | if (mac && mac->enabled) { | |
861 | macbuf = mac_compute(mac, p_send.seqnr, | |
862 | buffer_ptr(&outgoing_packet), | |
863 | buffer_len(&outgoing_packet)); | |
864 | DBG(debug("done calc MAC out #%d", p_send.seqnr)); | |
865 | } | |
866 | /* encrypt packet and append to output buffer. */ | |
867 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); | |
868 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
869 | buffer_len(&outgoing_packet)); | |
870 | /* append unencrypted MAC */ | |
871 | if (mac && mac->enabled) | |
872 | buffer_append(&output, macbuf, mac->mac_len); | |
873 | #ifdef PACKET_DEBUG | |
874 | fprintf(stderr, "encrypted: "); | |
875 | buffer_dump(&output); | |
876 | #endif | |
877 | /* increment sequence number for outgoing packets */ | |
878 | if (++p_send.seqnr == 0) | |
879 | logit("outgoing seqnr wraps around"); | |
880 | if (++p_send.packets == 0) | |
881 | if (!(datafellows & SSH_BUG_NOREKEY)) | |
882 | fatal("XXX too many packets with same key"); | |
883 | p_send.blocks += (packet_length + 4) / block_size; | |
884 | p_send.bytes += packet_length + 4; | |
885 | buffer_clear(&outgoing_packet); | |
886 | ||
887 | if (type == SSH2_MSG_NEWKEYS) | |
888 | set_newkeys(MODE_OUT); | |
889 | else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side) | |
890 | packet_enable_delayed_compress(); | |
891 | } | |
892 | ||
893 | static void | |
894 | packet_send2(void) | |
895 | { | |
896 | static int rekeying = 0; | |
897 | struct packet *p; | |
898 | u_char type, *cp; | |
899 | ||
900 | cp = buffer_ptr(&outgoing_packet); | |
901 | type = cp[5]; | |
902 | ||
903 | /* during rekeying we can only send key exchange messages */ | |
904 | if (rekeying) { | |
905 | if (!((type >= SSH2_MSG_TRANSPORT_MIN) && | |
906 | (type <= SSH2_MSG_TRANSPORT_MAX))) { | |
907 | debug("enqueue packet: %u", type); | |
908 | p = xmalloc(sizeof(*p)); | |
909 | p->type = type; | |
910 | memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); | |
911 | buffer_init(&outgoing_packet); | |
912 | TAILQ_INSERT_TAIL(&outgoing, p, next); | |
913 | return; | |
914 | } | |
915 | } | |
916 | ||
917 | /* rekeying starts with sending KEXINIT */ | |
918 | if (type == SSH2_MSG_KEXINIT) | |
919 | rekeying = 1; | |
920 | ||
921 | packet_send2_wrapped(); | |
922 | ||
923 | /* after a NEWKEYS message we can send the complete queue */ | |
924 | if (type == SSH2_MSG_NEWKEYS) { | |
925 | rekeying = 0; | |
926 | while ((p = TAILQ_FIRST(&outgoing))) { | |
927 | type = p->type; | |
928 | debug("dequeue packet: %u", type); | |
929 | buffer_free(&outgoing_packet); | |
930 | memcpy(&outgoing_packet, &p->payload, | |
931 | sizeof(Buffer)); | |
932 | TAILQ_REMOVE(&outgoing, p, next); | |
933 | xfree(p); | |
934 | packet_send2_wrapped(); | |
935 | } | |
936 | } | |
937 | } | |
938 | ||
939 | void | |
940 | packet_send(void) | |
941 | { | |
942 | if (compat20) | |
943 | packet_send2(); | |
944 | else | |
945 | packet_send1(); | |
946 | DBG(debug("packet_send done")); | |
947 | } | |
948 | ||
949 | /* | |
950 | * Waits until a packet has been received, and returns its type. Note that | |
951 | * no other data is processed until this returns, so this function should not | |
952 | * be used during the interactive session. | |
953 | */ | |
954 | ||
955 | int | |
956 | packet_read_seqnr(u_int32_t *seqnr_p) | |
957 | { | |
958 | int type, len, ret, ms_remain; | |
959 | fd_set *setp; | |
960 | char buf[8192]; | |
961 | struct timeval timeout, start, *timeoutp = NULL; | |
962 | ||
963 | DBG(debug("packet_read()")); | |
964 | ||
965 | setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS), | |
966 | sizeof(fd_mask)); | |
967 | ||
968 | /* Since we are blocking, ensure that all written packets have been sent. */ | |
969 | packet_write_wait(); | |
970 | ||
971 | /* Stay in the loop until we have received a complete packet. */ | |
972 | for (;;) { | |
973 | /* Try to read a packet from the buffer. */ | |
974 | type = packet_read_poll_seqnr(seqnr_p); | |
975 | if (!compat20 && ( | |
976 | type == SSH_SMSG_SUCCESS | |
977 | || type == SSH_SMSG_FAILURE | |
978 | || type == SSH_CMSG_EOF | |
979 | || type == SSH_CMSG_EXIT_CONFIRMATION)) | |
980 | packet_check_eom(); | |
981 | /* If we got a packet, return it. */ | |
982 | if (type != SSH_MSG_NONE) { | |
983 | xfree(setp); | |
984 | return type; | |
985 | } | |
986 | /* | |
987 | * Otherwise, wait for some data to arrive, add it to the | |
988 | * buffer, and try again. | |
989 | */ | |
990 | memset(setp, 0, howmany(connection_in + 1, NFDBITS) * | |
991 | sizeof(fd_mask)); | |
992 | FD_SET(connection_in, setp); | |
993 | ||
994 | if (packet_timeout_ms > 0) { | |
995 | ms_remain = packet_timeout_ms; | |
996 | timeoutp = &timeout; | |
997 | } | |
998 | /* Wait for some data to arrive. */ | |
999 | for (;;) { | |
1000 | if (packet_timeout_ms != -1) { | |
1001 | ms_to_timeval(&timeout, ms_remain); | |
1002 | gettimeofday(&start, NULL); | |
1003 | } | |
1004 | if ((ret = select(connection_in + 1, setp, NULL, | |
1005 | NULL, timeoutp)) >= 0) | |
1006 | break; | |
1007 | if (errno != EAGAIN && errno != EINTR && | |
1008 | errno != EWOULDBLOCK) | |
1009 | break; | |
1010 | if (packet_timeout_ms == -1) | |
1011 | continue; | |
1012 | ms_subtract_diff(&start, &ms_remain); | |
1013 | if (ms_remain <= 0) { | |
1014 | ret = 0; | |
1015 | break; | |
1016 | } | |
1017 | } | |
1018 | if (ret == 0) { | |
1019 | logit("Connection to %.200s timed out while " | |
1020 | "waiting to read", get_remote_ipaddr()); | |
1021 | cleanup_exit(255); | |
1022 | } | |
1023 | /* Read data from the socket. */ | |
1024 | len = read(connection_in, buf, sizeof(buf)); | |
1025 | if (len == 0) { | |
1026 | logit("Connection closed by %.200s", get_remote_ipaddr()); | |
1027 | cleanup_exit(255); | |
1028 | } | |
1029 | if (len < 0) | |
1030 | fatal("Read from socket failed: %.100s", strerror(errno)); | |
1031 | /* Append it to the buffer. */ | |
1032 | packet_process_incoming(buf, len); | |
1033 | } | |
1034 | /* NOTREACHED */ | |
1035 | } | |
1036 | ||
1037 | int | |
1038 | packet_read(void) | |
1039 | { | |
1040 | return packet_read_seqnr(NULL); | |
1041 | } | |
1042 | ||
1043 | /* | |
1044 | * Waits until a packet has been received, verifies that its type matches | |
1045 | * that given, and gives a fatal error and exits if there is a mismatch. | |
1046 | */ | |
1047 | ||
1048 | void | |
1049 | packet_read_expect(int expected_type) | |
1050 | { | |
1051 | int type; | |
1052 | ||
1053 | type = packet_read(); | |
1054 | if (type != expected_type) | |
1055 | packet_disconnect("Protocol error: expected packet type %d, got %d", | |
1056 | expected_type, type); | |
1057 | } | |
1058 | ||
1059 | /* Checks if a full packet is available in the data received so far via | |
1060 | * packet_process_incoming. If so, reads the packet; otherwise returns | |
1061 | * SSH_MSG_NONE. This does not wait for data from the connection. | |
1062 | * | |
1063 | * SSH_MSG_DISCONNECT is handled specially here. Also, | |
1064 | * SSH_MSG_IGNORE messages are skipped by this function and are never returned | |
1065 | * to higher levels. | |
1066 | */ | |
1067 | ||
1068 | static int | |
1069 | packet_read_poll1(void) | |
1070 | { | |
1071 | u_int len, padded_len; | |
1072 | u_char *cp, type; | |
1073 | u_int checksum, stored_checksum; | |
1074 | ||
1075 | /* Check if input size is less than minimum packet size. */ | |
1076 | if (buffer_len(&input) < 4 + 8) | |
1077 | return SSH_MSG_NONE; | |
1078 | /* Get length of incoming packet. */ | |
1079 | cp = buffer_ptr(&input); | |
1080 | len = get_u32(cp); | |
1081 | if (len < 1 + 2 + 2 || len > 256 * 1024) | |
1082 | packet_disconnect("Bad packet length %u.", len); | |
1083 | padded_len = (len + 8) & ~7; | |
1084 | ||
1085 | /* Check if the packet has been entirely received. */ | |
1086 | if (buffer_len(&input) < 4 + padded_len) | |
1087 | return SSH_MSG_NONE; | |
1088 | ||
1089 | /* The entire packet is in buffer. */ | |
1090 | ||
1091 | /* Consume packet length. */ | |
1092 | buffer_consume(&input, 4); | |
1093 | ||
1094 | /* | |
1095 | * Cryptographic attack detector for ssh | |
1096 | * (C)1998 CORE-SDI, Buenos Aires Argentina | |
1097 | * Ariel Futoransky(futo@core-sdi.com) | |
1098 | */ | |
1099 | if (!receive_context.plaintext) { | |
1100 | switch (detect_attack(buffer_ptr(&input), padded_len)) { | |
1101 | case DEATTACK_DETECTED: | |
1102 | packet_disconnect("crc32 compensation attack: " | |
1103 | "network attack detected"); | |
1104 | case DEATTACK_DOS_DETECTED: | |
1105 | packet_disconnect("deattack denial of " | |
1106 | "service detected"); | |
1107 | } | |
1108 | } | |
1109 | ||
1110 | /* Decrypt data to incoming_packet. */ | |
1111 | buffer_clear(&incoming_packet); | |
1112 | cp = buffer_append_space(&incoming_packet, padded_len); | |
1113 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); | |
1114 | ||
1115 | buffer_consume(&input, padded_len); | |
1116 | ||
1117 | #ifdef PACKET_DEBUG | |
1118 | fprintf(stderr, "read_poll plain: "); | |
1119 | buffer_dump(&incoming_packet); | |
1120 | #endif | |
1121 | ||
1122 | /* Compute packet checksum. */ | |
1123 | checksum = ssh_crc32(buffer_ptr(&incoming_packet), | |
1124 | buffer_len(&incoming_packet) - 4); | |
1125 | ||
1126 | /* Skip padding. */ | |
1127 | buffer_consume(&incoming_packet, 8 - len % 8); | |
1128 | ||
1129 | /* Test check bytes. */ | |
1130 | if (len != buffer_len(&incoming_packet)) | |
1131 | packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", | |
1132 | len, buffer_len(&incoming_packet)); | |
1133 | ||
1134 | cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; | |
1135 | stored_checksum = get_u32(cp); | |
1136 | if (checksum != stored_checksum) | |
1137 | packet_disconnect("Corrupted check bytes on input."); | |
1138 | buffer_consume_end(&incoming_packet, 4); | |
1139 | ||
1140 | if (packet_compression) { | |
1141 | buffer_clear(&compression_buffer); | |
1142 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
1143 | buffer_clear(&incoming_packet); | |
1144 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
1145 | buffer_len(&compression_buffer)); | |
1146 | } | |
1147 | p_read.packets++; | |
1148 | p_read.bytes += padded_len + 4; | |
1149 | type = buffer_get_char(&incoming_packet); | |
1150 | if (type < SSH_MSG_MIN || type > SSH_MSG_MAX) | |
1151 | packet_disconnect("Invalid ssh1 packet type: %d", type); | |
1152 | return type; | |
1153 | } | |
1154 | ||
1155 | static int | |
1156 | packet_read_poll2(u_int32_t *seqnr_p) | |
1157 | { | |
1158 | static u_int packet_length = 0; | |
1159 | u_int padlen, need; | |
1160 | u_char *macbuf, *cp, type; | |
1161 | u_int maclen, block_size; | |
1162 | Enc *enc = NULL; | |
1163 | Mac *mac = NULL; | |
1164 | Comp *comp = NULL; | |
1165 | ||
1166 | if (packet_discard) | |
1167 | return SSH_MSG_NONE; | |
1168 | ||
1169 | if (newkeys[MODE_IN] != NULL) { | |
1170 | enc = &newkeys[MODE_IN]->enc; | |
1171 | mac = &newkeys[MODE_IN]->mac; | |
1172 | comp = &newkeys[MODE_IN]->comp; | |
1173 | } | |
1174 | maclen = mac && mac->enabled ? mac->mac_len : 0; | |
1175 | block_size = enc ? enc->block_size : 8; | |
1176 | ||
1177 | if (packet_length == 0) { | |
1178 | /* | |
1179 | * check if input size is less than the cipher block size, | |
1180 | * decrypt first block and extract length of incoming packet | |
1181 | */ | |
1182 | if (buffer_len(&input) < block_size) | |
1183 | return SSH_MSG_NONE; | |
1184 | buffer_clear(&incoming_packet); | |
1185 | cp = buffer_append_space(&incoming_packet, block_size); | |
1186 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), | |
1187 | block_size); | |
1188 | cp = buffer_ptr(&incoming_packet); | |
1189 | packet_length = get_u32(cp); | |
1190 | if (packet_length < 1 + 4 || packet_length > PACKET_MAX_SIZE) { | |
1191 | #ifdef PACKET_DEBUG | |
1192 | buffer_dump(&incoming_packet); | |
1193 | #endif | |
1194 | logit("Bad packet length %u.", packet_length); | |
1195 | packet_start_discard(enc, mac, packet_length, | |
1196 | PACKET_MAX_SIZE); | |
1197 | return SSH_MSG_NONE; | |
1198 | } | |
1199 | DBG(debug("input: packet len %u", packet_length+4)); | |
1200 | buffer_consume(&input, block_size); | |
1201 | } | |
1202 | /* we have a partial packet of block_size bytes */ | |
1203 | need = 4 + packet_length - block_size; | |
1204 | DBG(debug("partial packet %d, need %d, maclen %d", block_size, | |
1205 | need, maclen)); | |
1206 | if (need % block_size != 0) { | |
1207 | logit("padding error: need %d block %d mod %d", | |
1208 | need, block_size, need % block_size); | |
1209 | packet_start_discard(enc, mac, packet_length, | |
1210 | PACKET_MAX_SIZE - block_size); | |
1211 | return SSH_MSG_NONE; | |
1212 | } | |
1213 | /* | |
1214 | * check if the entire packet has been received and | |
1215 | * decrypt into incoming_packet | |
1216 | */ | |
1217 | if (buffer_len(&input) < need + maclen) | |
1218 | return SSH_MSG_NONE; | |
1219 | #ifdef PACKET_DEBUG | |
1220 | fprintf(stderr, "read_poll enc/full: "); | |
1221 | buffer_dump(&input); | |
1222 | #endif | |
1223 | cp = buffer_append_space(&incoming_packet, need); | |
1224 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); | |
1225 | buffer_consume(&input, need); | |
1226 | /* | |
1227 | * compute MAC over seqnr and packet, | |
1228 | * increment sequence number for incoming packet | |
1229 | */ | |
1230 | if (mac && mac->enabled) { | |
1231 | macbuf = mac_compute(mac, p_read.seqnr, | |
1232 | buffer_ptr(&incoming_packet), | |
1233 | buffer_len(&incoming_packet)); | |
1234 | if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) { | |
1235 | logit("Corrupted MAC on input."); | |
1236 | if (need > PACKET_MAX_SIZE) | |
1237 | fatal("internal error need %d", need); | |
1238 | packet_start_discard(enc, mac, packet_length, | |
1239 | PACKET_MAX_SIZE - need); | |
1240 | return SSH_MSG_NONE; | |
1241 | } | |
1242 | ||
1243 | DBG(debug("MAC #%d ok", p_read.seqnr)); | |
1244 | buffer_consume(&input, mac->mac_len); | |
1245 | } | |
1246 | /* XXX now it's safe to use fatal/packet_disconnect */ | |
1247 | if (seqnr_p != NULL) | |
1248 | *seqnr_p = p_read.seqnr; | |
1249 | if (++p_read.seqnr == 0) | |
1250 | logit("incoming seqnr wraps around"); | |
1251 | if (++p_read.packets == 0) | |
1252 | if (!(datafellows & SSH_BUG_NOREKEY)) | |
1253 | fatal("XXX too many packets with same key"); | |
1254 | p_read.blocks += (packet_length + 4) / block_size; | |
1255 | p_read.bytes += packet_length + 4; | |
1256 | ||
1257 | /* get padlen */ | |
1258 | cp = buffer_ptr(&incoming_packet); | |
1259 | padlen = cp[4]; | |
1260 | DBG(debug("input: padlen %d", padlen)); | |
1261 | if (padlen < 4) | |
1262 | packet_disconnect("Corrupted padlen %d on input.", padlen); | |
1263 | ||
1264 | /* skip packet size + padlen, discard padding */ | |
1265 | buffer_consume(&incoming_packet, 4 + 1); | |
1266 | buffer_consume_end(&incoming_packet, padlen); | |
1267 | ||
1268 | DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); | |
1269 | if (comp && comp->enabled) { | |
1270 | buffer_clear(&compression_buffer); | |
1271 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
1272 | buffer_clear(&incoming_packet); | |
1273 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
1274 | buffer_len(&compression_buffer)); | |
1275 | DBG(debug("input: len after de-compress %d", | |
1276 | buffer_len(&incoming_packet))); | |
1277 | } | |
1278 | /* | |
1279 | * get packet type, implies consume. | |
1280 | * return length of payload (without type field) | |
1281 | */ | |
1282 | type = buffer_get_char(&incoming_packet); | |
1283 | if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN) | |
1284 | packet_disconnect("Invalid ssh2 packet type: %d", type); | |
1285 | if (type == SSH2_MSG_NEWKEYS) | |
1286 | set_newkeys(MODE_IN); | |
1287 | else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side) | |
1288 | packet_enable_delayed_compress(); | |
1289 | #ifdef PACKET_DEBUG | |
1290 | fprintf(stderr, "read/plain[%d]:\r\n", type); | |
1291 | buffer_dump(&incoming_packet); | |
1292 | #endif | |
1293 | /* reset for next packet */ | |
1294 | packet_length = 0; | |
1295 | return type; | |
1296 | } | |
1297 | ||
1298 | int | |
1299 | packet_read_poll_seqnr(u_int32_t *seqnr_p) | |
1300 | { | |
1301 | u_int reason, seqnr; | |
1302 | u_char type; | |
1303 | char *msg; | |
1304 | ||
1305 | for (;;) { | |
1306 | if (compat20) { | |
1307 | type = packet_read_poll2(seqnr_p); | |
1308 | if (type) { | |
1309 | keep_alive_timeouts = 0; | |
1310 | DBG(debug("received packet type %d", type)); | |
1311 | } | |
1312 | switch (type) { | |
1313 | case SSH2_MSG_IGNORE: | |
1314 | debug3("Received SSH2_MSG_IGNORE"); | |
1315 | break; | |
1316 | case SSH2_MSG_DEBUG: | |
1317 | packet_get_char(); | |
1318 | msg = packet_get_string(NULL); | |
1319 | debug("Remote: %.900s", msg); | |
1320 | xfree(msg); | |
1321 | msg = packet_get_string(NULL); | |
1322 | xfree(msg); | |
1323 | break; | |
1324 | case SSH2_MSG_DISCONNECT: | |
1325 | reason = packet_get_int(); | |
1326 | msg = packet_get_string(NULL); | |
1327 | logit("Received disconnect from %s: %u: %.400s", | |
1328 | get_remote_ipaddr(), reason, msg); | |
1329 | xfree(msg); | |
1330 | cleanup_exit(255); | |
1331 | break; | |
1332 | case SSH2_MSG_UNIMPLEMENTED: | |
1333 | seqnr = packet_get_int(); | |
1334 | debug("Received SSH2_MSG_UNIMPLEMENTED for %u", | |
1335 | seqnr); | |
1336 | break; | |
1337 | default: | |
1338 | return type; | |
1339 | } | |
1340 | } else { | |
1341 | type = packet_read_poll1(); | |
1342 | switch (type) { | |
1343 | case SSH_MSG_IGNORE: | |
1344 | break; | |
1345 | case SSH_MSG_DEBUG: | |
1346 | msg = packet_get_string(NULL); | |
1347 | debug("Remote: %.900s", msg); | |
1348 | xfree(msg); | |
1349 | break; | |
1350 | case SSH_MSG_DISCONNECT: | |
1351 | msg = packet_get_string(NULL); | |
1352 | logit("Received disconnect from %s: %.400s", | |
1353 | get_remote_ipaddr(), msg); | |
1354 | cleanup_exit(255); | |
1355 | break; | |
1356 | default: | |
1357 | if (type) | |
1358 | DBG(debug("received packet type %d", type)); | |
1359 | return type; | |
1360 | } | |
1361 | } | |
1362 | } | |
1363 | } | |
1364 | ||
1365 | int | |
1366 | packet_read_poll(void) | |
1367 | { | |
1368 | return packet_read_poll_seqnr(NULL); | |
1369 | } | |
1370 | ||
1371 | /* | |
1372 | * Buffers the given amount of input characters. This is intended to be used | |
1373 | * together with packet_read_poll. | |
1374 | */ | |
1375 | ||
1376 | void | |
1377 | packet_process_incoming(const char *buf, u_int len) | |
1378 | { | |
1379 | if (packet_discard) { | |
1380 | keep_alive_timeouts = 0; /* ?? */ | |
1381 | if (len >= packet_discard) | |
1382 | packet_stop_discard(); | |
1383 | packet_discard -= len; | |
1384 | return; | |
1385 | } | |
1386 | buffer_append(&input, buf, len); | |
1387 | } | |
1388 | ||
1389 | /* Returns a character from the packet. */ | |
1390 | ||
1391 | u_int | |
1392 | packet_get_char(void) | |
1393 | { | |
1394 | char ch; | |
1395 | ||
1396 | buffer_get(&incoming_packet, &ch, 1); | |
1397 | return (u_char) ch; | |
1398 | } | |
1399 | ||
1400 | /* Returns an integer from the packet data. */ | |
1401 | ||
1402 | u_int | |
1403 | packet_get_int(void) | |
1404 | { | |
1405 | return buffer_get_int(&incoming_packet); | |
1406 | } | |
1407 | ||
1408 | /* | |
1409 | * Returns an arbitrary precision integer from the packet data. The integer | |
1410 | * must have been initialized before this call. | |
1411 | */ | |
1412 | ||
1413 | void | |
1414 | packet_get_bignum(BIGNUM * value) | |
1415 | { | |
1416 | buffer_get_bignum(&incoming_packet, value); | |
1417 | } | |
1418 | ||
1419 | void | |
1420 | packet_get_bignum2(BIGNUM * value) | |
1421 | { | |
1422 | buffer_get_bignum2(&incoming_packet, value); | |
1423 | } | |
1424 | ||
1425 | void * | |
1426 | packet_get_raw(u_int *length_ptr) | |
1427 | { | |
1428 | u_int bytes = buffer_len(&incoming_packet); | |
1429 | ||
1430 | if (length_ptr != NULL) | |
1431 | *length_ptr = bytes; | |
1432 | return buffer_ptr(&incoming_packet); | |
1433 | } | |
1434 | ||
1435 | int | |
1436 | packet_remaining(void) | |
1437 | { | |
1438 | return buffer_len(&incoming_packet); | |
1439 | } | |
1440 | ||
1441 | /* | |
1442 | * Returns a string from the packet data. The string is allocated using | |
1443 | * xmalloc; it is the responsibility of the calling program to free it when | |
1444 | * no longer needed. The length_ptr argument may be NULL, or point to an | |
1445 | * integer into which the length of the string is stored. | |
1446 | */ | |
1447 | ||
1448 | void * | |
1449 | packet_get_string(u_int *length_ptr) | |
1450 | { | |
1451 | return buffer_get_string(&incoming_packet, length_ptr); | |
1452 | } | |
1453 | ||
1454 | void * | |
1455 | packet_get_string_ptr(u_int *length_ptr) | |
1456 | { | |
1457 | return buffer_get_string_ptr(&incoming_packet, length_ptr); | |
1458 | } | |
1459 | ||
1460 | /* | |
1461 | * Sends a diagnostic message from the server to the client. This message | |
1462 | * can be sent at any time (but not while constructing another message). The | |
1463 | * message is printed immediately, but only if the client is being executed | |
1464 | * in verbose mode. These messages are primarily intended to ease debugging | |
1465 | * authentication problems. The length of the formatted message must not | |
1466 | * exceed 1024 bytes. This will automatically call packet_write_wait. | |
1467 | */ | |
1468 | ||
1469 | void | |
1470 | packet_send_debug(const char *fmt,...) | |
1471 | { | |
1472 | char buf[1024]; | |
1473 | va_list args; | |
1474 | ||
1475 | if (compat20 && (datafellows & SSH_BUG_DEBUG)) | |
1476 | return; | |
1477 | ||
1478 | va_start(args, fmt); | |
1479 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1480 | va_end(args); | |
1481 | ||
1482 | if (compat20) { | |
1483 | packet_start(SSH2_MSG_DEBUG); | |
1484 | packet_put_char(0); /* bool: always display */ | |
1485 | packet_put_cstring(buf); | |
1486 | packet_put_cstring(""); | |
1487 | } else { | |
1488 | packet_start(SSH_MSG_DEBUG); | |
1489 | packet_put_cstring(buf); | |
1490 | } | |
1491 | packet_send(); | |
1492 | packet_write_wait(); | |
1493 | } | |
1494 | ||
1495 | /* | |
1496 | * Logs the error plus constructs and sends a disconnect packet, closes the | |
1497 | * connection, and exits. This function never returns. The error message | |
1498 | * should not contain a newline. The length of the formatted message must | |
1499 | * not exceed 1024 bytes. | |
1500 | */ | |
1501 | ||
1502 | void | |
1503 | packet_disconnect(const char *fmt,...) | |
1504 | { | |
1505 | char buf[1024]; | |
1506 | va_list args; | |
1507 | static int disconnecting = 0; | |
1508 | ||
1509 | if (disconnecting) /* Guard against recursive invocations. */ | |
1510 | fatal("packet_disconnect called recursively."); | |
1511 | disconnecting = 1; | |
1512 | ||
1513 | /* | |
1514 | * Format the message. Note that the caller must make sure the | |
1515 | * message is of limited size. | |
1516 | */ | |
1517 | va_start(args, fmt); | |
1518 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1519 | va_end(args); | |
1520 | ||
1521 | /* Display the error locally */ | |
1522 | logit("Disconnecting: %.100s", buf); | |
1523 | ||
1524 | /* Send the disconnect message to the other side, and wait for it to get sent. */ | |
1525 | if (compat20) { | |
1526 | packet_start(SSH2_MSG_DISCONNECT); | |
1527 | packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); | |
1528 | packet_put_cstring(buf); | |
1529 | packet_put_cstring(""); | |
1530 | } else { | |
1531 | packet_start(SSH_MSG_DISCONNECT); | |
1532 | packet_put_cstring(buf); | |
1533 | } | |
1534 | packet_send(); | |
1535 | packet_write_wait(); | |
1536 | ||
1537 | /* Stop listening for connections. */ | |
1538 | channel_close_all(); | |
1539 | ||
1540 | /* Close the connection. */ | |
1541 | packet_close(); | |
1542 | cleanup_exit(255); | |
1543 | } | |
1544 | ||
1545 | /* Checks if there is any buffered output, and tries to write some of the output. */ | |
1546 | ||
1547 | void | |
1548 | packet_write_poll(void) | |
1549 | { | |
1550 | int len = buffer_len(&output); | |
1551 | ||
1552 | if (len > 0) { | |
1553 | len = write(connection_out, buffer_ptr(&output), len); | |
1554 | if (len == -1) { | |
1555 | if (errno == EINTR || errno == EAGAIN || | |
1556 | errno == EWOULDBLOCK) | |
1557 | return; | |
1558 | fatal("Write failed: %.100s", strerror(errno)); | |
1559 | } | |
1560 | if (len == 0) | |
1561 | fatal("Write connection closed"); | |
1562 | buffer_consume(&output, len); | |
1563 | } | |
1564 | } | |
1565 | ||
1566 | ||
1567 | /* | |
1568 | * Calls packet_write_poll repeatedly until all pending output data has been | |
1569 | * written. | |
1570 | */ | |
1571 | ||
1572 | void | |
1573 | packet_write_wait(void) | |
1574 | { | |
1575 | fd_set *setp; | |
1576 | int ret, ms_remain; | |
1577 | struct timeval start, timeout, *timeoutp = NULL; | |
1578 | ||
1579 | setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS), | |
1580 | sizeof(fd_mask)); | |
1581 | packet_write_poll(); | |
1582 | while (packet_have_data_to_write()) { | |
1583 | memset(setp, 0, howmany(connection_out + 1, NFDBITS) * | |
1584 | sizeof(fd_mask)); | |
1585 | FD_SET(connection_out, setp); | |
1586 | ||
1587 | if (packet_timeout_ms > 0) { | |
1588 | ms_remain = packet_timeout_ms; | |
1589 | timeoutp = &timeout; | |
1590 | } | |
1591 | for (;;) { | |
1592 | if (packet_timeout_ms != -1) { | |
1593 | ms_to_timeval(&timeout, ms_remain); | |
1594 | gettimeofday(&start, NULL); | |
1595 | } | |
1596 | if ((ret = select(connection_out + 1, NULL, setp, | |
1597 | NULL, timeoutp)) >= 0) | |
1598 | break; | |
1599 | if (errno != EAGAIN && errno != EINTR && | |
1600 | errno != EWOULDBLOCK) | |
1601 | break; | |
1602 | if (packet_timeout_ms == -1) | |
1603 | continue; | |
1604 | ms_subtract_diff(&start, &ms_remain); | |
1605 | if (ms_remain <= 0) { | |
1606 | ret = 0; | |
1607 | break; | |
1608 | } | |
1609 | } | |
1610 | if (ret == 0) { | |
1611 | logit("Connection to %.200s timed out while " | |
1612 | "waiting to write", get_remote_ipaddr()); | |
1613 | cleanup_exit(255); | |
1614 | } | |
1615 | packet_write_poll(); | |
1616 | } | |
1617 | xfree(setp); | |
1618 | } | |
1619 | ||
1620 | /* Returns true if there is buffered data to write to the connection. */ | |
1621 | ||
1622 | int | |
1623 | packet_have_data_to_write(void) | |
1624 | { | |
1625 | return buffer_len(&output) != 0; | |
1626 | } | |
1627 | ||
1628 | /* Returns true if there is not too much data to write to the connection. */ | |
1629 | ||
1630 | int | |
1631 | packet_not_very_much_data_to_write(void) | |
1632 | { | |
1633 | if (interactive_mode) | |
1634 | return buffer_len(&output) < 16384; | |
1635 | else | |
1636 | return buffer_len(&output) < 128 * 1024; | |
1637 | } | |
1638 | ||
1639 | ||
1640 | static void | |
1641 | packet_set_tos(int interactive) | |
1642 | { | |
1643 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) | |
1644 | int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; | |
1645 | ||
1646 | if (!packet_connection_is_on_socket() || | |
1647 | !packet_connection_is_ipv4()) | |
1648 | return; | |
1649 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, | |
1650 | sizeof(tos)) < 0) | |
1651 | error("setsockopt IP_TOS %d: %.100s:", | |
1652 | tos, strerror(errno)); | |
1653 | #endif | |
1654 | } | |
1655 | ||
1656 | /* Informs that the current session is interactive. Sets IP flags for that. */ | |
1657 | ||
1658 | void | |
1659 | packet_set_interactive(int interactive) | |
1660 | { | |
1661 | static int called = 0; | |
1662 | ||
1663 | if (called) | |
1664 | return; | |
1665 | called = 1; | |
1666 | ||
1667 | /* Record that we are in interactive mode. */ | |
1668 | interactive_mode = interactive; | |
1669 | ||
1670 | /* Only set socket options if using a socket. */ | |
1671 | if (!packet_connection_is_on_socket()) | |
1672 | return; | |
1673 | set_nodelay(connection_in); | |
1674 | packet_set_tos(interactive); | |
1675 | } | |
1676 | ||
1677 | /* Returns true if the current connection is interactive. */ | |
1678 | ||
1679 | int | |
1680 | packet_is_interactive(void) | |
1681 | { | |
1682 | return interactive_mode; | |
1683 | } | |
1684 | ||
1685 | int | |
1686 | packet_set_maxsize(u_int s) | |
1687 | { | |
1688 | static int called = 0; | |
1689 | ||
1690 | if (called) { | |
1691 | logit("packet_set_maxsize: called twice: old %d new %d", | |
1692 | max_packet_size, s); | |
1693 | return -1; | |
1694 | } | |
1695 | if (s < 4 * 1024 || s > 1024 * 1024) { | |
1696 | logit("packet_set_maxsize: bad size %d", s); | |
1697 | return -1; | |
1698 | } | |
1699 | called = 1; | |
1700 | debug("packet_set_maxsize: setting to %d", s); | |
1701 | max_packet_size = s; | |
1702 | return s; | |
1703 | } | |
1704 | ||
1705 | /* roundup current message to pad bytes */ | |
1706 | void | |
1707 | packet_add_padding(u_char pad) | |
1708 | { | |
1709 | extra_pad = pad; | |
1710 | } | |
1711 | ||
1712 | /* | |
1713 | * 9.2. Ignored Data Message | |
1714 | * | |
1715 | * byte SSH_MSG_IGNORE | |
1716 | * string data | |
1717 | * | |
1718 | * All implementations MUST understand (and ignore) this message at any | |
1719 | * time (after receiving the protocol version). No implementation is | |
1720 | * required to send them. This message can be used as an additional | |
1721 | * protection measure against advanced traffic analysis techniques. | |
1722 | */ | |
1723 | void | |
1724 | packet_send_ignore(int nbytes) | |
1725 | { | |
1726 | u_int32_t rnd = 0; | |
1727 | int i; | |
1728 | ||
1729 | packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); | |
1730 | packet_put_int(nbytes); | |
1731 | for (i = 0; i < nbytes; i++) { | |
1732 | if (i % 4 == 0) | |
1733 | rnd = arc4random(); | |
1734 | packet_put_char((u_char)rnd & 0xff); | |
1735 | rnd >>= 8; | |
1736 | } | |
1737 | } | |
1738 | ||
1739 | #define MAX_PACKETS (1U<<31) | |
1740 | int | |
1741 | packet_need_rekeying(void) | |
1742 | { | |
1743 | if (datafellows & SSH_BUG_NOREKEY) | |
1744 | return 0; | |
1745 | return | |
1746 | (p_send.packets > MAX_PACKETS) || | |
1747 | (p_read.packets > MAX_PACKETS) || | |
1748 | (max_blocks_out && (p_send.blocks > max_blocks_out)) || | |
1749 | (max_blocks_in && (p_read.blocks > max_blocks_in)); | |
1750 | } | |
1751 | ||
1752 | void | |
1753 | packet_set_rekey_limit(u_int32_t bytes) | |
1754 | { | |
1755 | rekey_limit = bytes; | |
1756 | } | |
1757 | ||
1758 | void | |
1759 | packet_set_server(void) | |
1760 | { | |
1761 | server_side = 1; | |
1762 | } | |
1763 | ||
1764 | void | |
1765 | packet_set_authenticated(void) | |
1766 | { | |
1767 | after_authentication = 1; | |
1768 | } |