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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 1.93 2002/03/24 16:01:13 markus Exp $"); | |
41 | ||
42 | #include "xmalloc.h" | |
43 | #include "buffer.h" | |
44 | #include "packet.h" | |
45 | #include "bufaux.h" | |
46 | #include "crc32.h" | |
47 | #include "getput.h" | |
48 | ||
49 | #include "compress.h" | |
50 | #include "deattack.h" | |
51 | #include "channels.h" | |
52 | ||
53 | #include "compat.h" | |
54 | #include "ssh1.h" | |
55 | #include "ssh2.h" | |
56 | ||
57 | #include "cipher.h" | |
58 | #include "kex.h" | |
59 | #include "mac.h" | |
60 | #include "log.h" | |
61 | #include "canohost.h" | |
62 | #include "misc.h" | |
63 | ||
64 | #ifdef PACKET_DEBUG | |
65 | #define DBG(x) x | |
66 | #else | |
67 | #define DBG(x) | |
68 | #endif | |
69 | ||
70 | /* | |
71 | * This variable contains the file descriptors used for communicating with | |
72 | * the other side. connection_in is used for reading; connection_out for | |
73 | * writing. These can be the same descriptor, in which case it is assumed to | |
74 | * be a socket. | |
75 | */ | |
76 | static int connection_in = -1; | |
77 | static int connection_out = -1; | |
78 | ||
79 | /* Protocol flags for the remote side. */ | |
80 | static u_int remote_protocol_flags = 0; | |
81 | ||
82 | /* Encryption context for receiving data. This is only used for decryption. */ | |
83 | static CipherContext receive_context; | |
84 | ||
85 | /* Encryption context for sending data. This is only used for encryption. */ | |
86 | static CipherContext send_context; | |
87 | ||
88 | /* Buffer for raw input data from the socket. */ | |
89 | Buffer input; | |
90 | ||
91 | /* Buffer for raw output data going to the socket. */ | |
92 | Buffer output; | |
93 | ||
94 | /* Buffer for the partial outgoing packet being constructed. */ | |
95 | static Buffer outgoing_packet; | |
96 | ||
97 | /* Buffer for the incoming packet currently being processed. */ | |
98 | static Buffer incoming_packet; | |
99 | ||
100 | /* Scratch buffer for packet compression/decompression. */ | |
101 | static Buffer compression_buffer; | |
102 | static int compression_buffer_ready = 0; | |
103 | ||
104 | /* Flag indicating whether packet compression/decompression is enabled. */ | |
105 | static int packet_compression = 0; | |
106 | ||
107 | /* default maximum packet size */ | |
108 | int max_packet_size = 32768; | |
109 | ||
110 | /* Flag indicating whether this module has been initialized. */ | |
111 | static int initialized = 0; | |
112 | ||
113 | /* Set to true if the connection is interactive. */ | |
114 | static int interactive_mode = 0; | |
115 | ||
116 | /* Session key information for Encryption and MAC */ | |
117 | Newkeys *newkeys[MODE_MAX]; | |
118 | static u_int32_t read_seqnr = 0; | |
119 | static u_int32_t send_seqnr = 0; | |
120 | ||
121 | /* roundup current message to extra_pad bytes */ | |
122 | static u_char extra_pad = 0; | |
123 | ||
124 | /* | |
125 | * Sets the descriptors used for communication. Disables encryption until | |
126 | * packet_set_encryption_key is called. | |
127 | */ | |
128 | void | |
129 | packet_set_connection(int fd_in, int fd_out) | |
130 | { | |
131 | Cipher *none = cipher_by_name("none"); | |
132 | if (none == NULL) | |
133 | fatal("packet_set_connection: cannot load cipher 'none'"); | |
134 | connection_in = fd_in; | |
135 | connection_out = fd_out; | |
136 | cipher_init(&send_context, none, "", 0, NULL, 0, CIPHER_ENCRYPT); | |
137 | cipher_init(&receive_context, none, "", 0, NULL, 0, CIPHER_DECRYPT); | |
138 | newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; | |
139 | if (!initialized) { | |
140 | initialized = 1; | |
141 | buffer_init(&input); | |
142 | buffer_init(&output); | |
143 | buffer_init(&outgoing_packet); | |
144 | buffer_init(&incoming_packet); | |
145 | } | |
146 | /* Kludge: arrange the close function to be called from fatal(). */ | |
147 | fatal_add_cleanup((void (*) (void *)) packet_close, NULL); | |
148 | } | |
149 | ||
150 | /* Returns 1 if remote host is connected via socket, 0 if not. */ | |
151 | ||
152 | int | |
153 | packet_connection_is_on_socket(void) | |
154 | { | |
155 | struct sockaddr_storage from, to; | |
156 | socklen_t fromlen, tolen; | |
157 | ||
158 | /* filedescriptors in and out are the same, so it's a socket */ | |
159 | if (connection_in == connection_out) | |
160 | return 1; | |
161 | fromlen = sizeof(from); | |
162 | memset(&from, 0, sizeof(from)); | |
163 | if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) | |
164 | return 0; | |
165 | tolen = sizeof(to); | |
166 | memset(&to, 0, sizeof(to)); | |
167 | if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
168 | return 0; | |
169 | if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) | |
170 | return 0; | |
171 | if (from.ss_family != AF_INET && from.ss_family != AF_INET6) | |
172 | return 0; | |
173 | return 1; | |
174 | } | |
175 | ||
176 | /* | |
177 | * Exports an IV from the CipherContext required to export the key | |
178 | * state back from the unprivileged child to the privileged parent | |
179 | * process. | |
180 | */ | |
181 | ||
182 | void | |
183 | packet_get_keyiv(int mode, u_char *iv, u_int len) | |
184 | { | |
185 | CipherContext *cc; | |
186 | ||
187 | if (mode == MODE_OUT) | |
188 | cc = &send_context; | |
189 | else | |
190 | cc = &receive_context; | |
191 | ||
192 | cipher_get_keyiv(cc, iv, len); | |
193 | } | |
194 | ||
195 | int | |
196 | packet_get_keycontext(int mode, u_char *dat) | |
197 | { | |
198 | CipherContext *cc; | |
199 | ||
200 | if (mode == MODE_OUT) | |
201 | cc = &send_context; | |
202 | else | |
203 | cc = &receive_context; | |
204 | ||
205 | return (cipher_get_keycontext(cc, dat)); | |
206 | } | |
207 | ||
208 | void | |
209 | packet_set_keycontext(int mode, u_char *dat) | |
210 | { | |
211 | CipherContext *cc; | |
212 | ||
213 | if (mode == MODE_OUT) | |
214 | cc = &send_context; | |
215 | else | |
216 | cc = &receive_context; | |
217 | ||
218 | cipher_set_keycontext(cc, dat); | |
219 | } | |
220 | ||
221 | int | |
222 | packet_get_keyiv_len(int mode) | |
223 | { | |
224 | CipherContext *cc; | |
225 | ||
226 | if (mode == MODE_OUT) | |
227 | cc = &send_context; | |
228 | else | |
229 | cc = &receive_context; | |
230 | ||
231 | return (cipher_get_keyiv_len(cc)); | |
232 | } | |
233 | void | |
234 | packet_set_iv(int mode, u_char *dat) | |
235 | { | |
236 | CipherContext *cc; | |
237 | ||
238 | if (mode == MODE_OUT) | |
239 | cc = &send_context; | |
240 | else | |
241 | cc = &receive_context; | |
242 | ||
243 | cipher_set_keyiv(cc, dat); | |
244 | } | |
245 | int | |
246 | packet_get_ssh1_cipher() | |
247 | { | |
248 | return (cipher_get_number(receive_context.cipher)); | |
249 | } | |
250 | ||
251 | ||
252 | u_int32_t | |
253 | packet_get_seqnr(int mode) | |
254 | { | |
255 | return (mode == MODE_IN ? read_seqnr : send_seqnr); | |
256 | } | |
257 | ||
258 | void | |
259 | packet_set_seqnr(int mode, u_int32_t seqnr) | |
260 | { | |
261 | if (mode == MODE_IN) | |
262 | read_seqnr = seqnr; | |
263 | else if (mode == MODE_OUT) | |
264 | send_seqnr = seqnr; | |
265 | else | |
266 | fatal("%s: bad mode %d", __FUNCTION__, mode); | |
267 | } | |
268 | ||
269 | /* returns 1 if connection is via ipv4 */ | |
270 | ||
271 | int | |
272 | packet_connection_is_ipv4(void) | |
273 | { | |
274 | struct sockaddr_storage to; | |
275 | socklen_t tolen = sizeof(to); | |
276 | ||
277 | memset(&to, 0, sizeof(to)); | |
278 | if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
279 | return 0; | |
280 | if (to.ss_family == AF_INET) | |
281 | return 1; | |
282 | #ifdef IPV4_IN_IPV6 | |
283 | if (to.ss_family == AF_INET6 && | |
284 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) | |
285 | return 1; | |
286 | #endif | |
287 | return 0; | |
288 | } | |
289 | ||
290 | /* Sets the connection into non-blocking mode. */ | |
291 | ||
292 | void | |
293 | packet_set_nonblocking(void) | |
294 | { | |
295 | /* Set the socket into non-blocking mode. */ | |
296 | if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) | |
297 | error("fcntl O_NONBLOCK: %.100s", strerror(errno)); | |
298 | ||
299 | if (connection_out != connection_in) { | |
300 | if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0) | |
301 | error("fcntl O_NONBLOCK: %.100s", strerror(errno)); | |
302 | } | |
303 | } | |
304 | ||
305 | /* Returns the socket used for reading. */ | |
306 | ||
307 | int | |
308 | packet_get_connection_in(void) | |
309 | { | |
310 | return connection_in; | |
311 | } | |
312 | ||
313 | /* Returns the descriptor used for writing. */ | |
314 | ||
315 | int | |
316 | packet_get_connection_out(void) | |
317 | { | |
318 | return connection_out; | |
319 | } | |
320 | ||
321 | /* Closes the connection and clears and frees internal data structures. */ | |
322 | ||
323 | void | |
324 | packet_close(void) | |
325 | { | |
326 | if (!initialized) | |
327 | return; | |
328 | initialized = 0; | |
329 | if (connection_in == connection_out) { | |
330 | shutdown(connection_out, SHUT_RDWR); | |
331 | close(connection_out); | |
332 | } else { | |
333 | close(connection_in); | |
334 | close(connection_out); | |
335 | } | |
336 | buffer_free(&input); | |
337 | buffer_free(&output); | |
338 | buffer_free(&outgoing_packet); | |
339 | buffer_free(&incoming_packet); | |
340 | if (compression_buffer_ready) { | |
341 | buffer_free(&compression_buffer); | |
342 | buffer_compress_uninit(); | |
343 | } | |
344 | cipher_cleanup(&send_context); | |
345 | cipher_cleanup(&receive_context); | |
346 | } | |
347 | ||
348 | /* Sets remote side protocol flags. */ | |
349 | ||
350 | void | |
351 | packet_set_protocol_flags(u_int protocol_flags) | |
352 | { | |
353 | remote_protocol_flags = protocol_flags; | |
354 | } | |
355 | ||
356 | /* Returns the remote protocol flags set earlier by the above function. */ | |
357 | ||
358 | u_int | |
359 | packet_get_protocol_flags(void) | |
360 | { | |
361 | return remote_protocol_flags; | |
362 | } | |
363 | ||
364 | /* | |
365 | * Starts packet compression from the next packet on in both directions. | |
366 | * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. | |
367 | */ | |
368 | ||
369 | static void | |
370 | packet_init_compression(void) | |
371 | { | |
372 | if (compression_buffer_ready == 1) | |
373 | return; | |
374 | compression_buffer_ready = 1; | |
375 | buffer_init(&compression_buffer); | |
376 | } | |
377 | ||
378 | void | |
379 | packet_start_compression(int level) | |
380 | { | |
381 | if (packet_compression && !compat20) | |
382 | fatal("Compression already enabled."); | |
383 | packet_compression = 1; | |
384 | packet_init_compression(); | |
385 | buffer_compress_init_send(level); | |
386 | buffer_compress_init_recv(); | |
387 | } | |
388 | ||
389 | /* | |
390 | * Causes any further packets to be encrypted using the given key. The same | |
391 | * key is used for both sending and reception. However, both directions are | |
392 | * encrypted independently of each other. | |
393 | */ | |
394 | void | |
395 | packet_set_encryption_key(const u_char *key, u_int keylen, | |
396 | int number) | |
397 | { | |
398 | Cipher *cipher = cipher_by_number(number); | |
399 | if (cipher == NULL) | |
400 | fatal("packet_set_encryption_key: unknown cipher number %d", number); | |
401 | if (keylen < 20) | |
402 | fatal("packet_set_encryption_key: keylen too small: %d", keylen); | |
403 | cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); | |
404 | cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); | |
405 | } | |
406 | ||
407 | /* Start constructing a packet to send. */ | |
408 | void | |
409 | packet_start(u_char type) | |
410 | { | |
411 | u_char buf[9]; | |
412 | int len; | |
413 | ||
414 | DBG(debug("packet_start[%d]", type)); | |
415 | len = compat20 ? 6 : 9; | |
416 | memset(buf, 0, len - 1); | |
417 | buf[len - 1] = type; | |
418 | buffer_clear(&outgoing_packet); | |
419 | buffer_append(&outgoing_packet, buf, len); | |
420 | } | |
421 | ||
422 | /* Append payload. */ | |
423 | void | |
424 | packet_put_char(int value) | |
425 | { | |
426 | char ch = value; | |
427 | buffer_append(&outgoing_packet, &ch, 1); | |
428 | } | |
429 | void | |
430 | packet_put_int(u_int value) | |
431 | { | |
432 | buffer_put_int(&outgoing_packet, value); | |
433 | } | |
434 | void | |
435 | packet_put_string(const void *buf, u_int len) | |
436 | { | |
437 | buffer_put_string(&outgoing_packet, buf, len); | |
438 | } | |
439 | void | |
440 | packet_put_cstring(const char *str) | |
441 | { | |
442 | buffer_put_cstring(&outgoing_packet, str); | |
443 | } | |
444 | void | |
445 | packet_put_raw(const void *buf, u_int len) | |
446 | { | |
447 | buffer_append(&outgoing_packet, buf, len); | |
448 | } | |
449 | void | |
450 | packet_put_bignum(BIGNUM * value) | |
451 | { | |
452 | buffer_put_bignum(&outgoing_packet, value); | |
453 | } | |
454 | void | |
455 | packet_put_bignum2(BIGNUM * value) | |
456 | { | |
457 | buffer_put_bignum2(&outgoing_packet, value); | |
458 | } | |
459 | ||
460 | /* | |
461 | * Finalizes and sends the packet. If the encryption key has been set, | |
462 | * encrypts the packet before sending. | |
463 | */ | |
464 | ||
465 | static void | |
466 | packet_send1(void) | |
467 | { | |
468 | u_char buf[8], *cp; | |
469 | int i, padding, len; | |
470 | u_int checksum; | |
471 | u_int32_t rand = 0; | |
472 | ||
473 | /* | |
474 | * If using packet compression, compress the payload of the outgoing | |
475 | * packet. | |
476 | */ | |
477 | if (packet_compression) { | |
478 | buffer_clear(&compression_buffer); | |
479 | /* Skip padding. */ | |
480 | buffer_consume(&outgoing_packet, 8); | |
481 | /* padding */ | |
482 | buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); | |
483 | buffer_compress(&outgoing_packet, &compression_buffer); | |
484 | buffer_clear(&outgoing_packet); | |
485 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
486 | buffer_len(&compression_buffer)); | |
487 | } | |
488 | /* Compute packet length without padding (add checksum, remove padding). */ | |
489 | len = buffer_len(&outgoing_packet) + 4 - 8; | |
490 | ||
491 | /* Insert padding. Initialized to zero in packet_start1() */ | |
492 | padding = 8 - len % 8; | |
493 | if (!send_context.plaintext) { | |
494 | cp = buffer_ptr(&outgoing_packet); | |
495 | for (i = 0; i < padding; i++) { | |
496 | if (i % 4 == 0) | |
497 | rand = arc4random(); | |
498 | cp[7 - i] = rand & 0xff; | |
499 | rand >>= 8; | |
500 | } | |
501 | } | |
502 | buffer_consume(&outgoing_packet, 8 - padding); | |
503 | ||
504 | /* Add check bytes. */ | |
505 | checksum = ssh_crc32(buffer_ptr(&outgoing_packet), | |
506 | buffer_len(&outgoing_packet)); | |
507 | PUT_32BIT(buf, checksum); | |
508 | buffer_append(&outgoing_packet, buf, 4); | |
509 | ||
510 | #ifdef PACKET_DEBUG | |
511 | fprintf(stderr, "packet_send plain: "); | |
512 | buffer_dump(&outgoing_packet); | |
513 | #endif | |
514 | ||
515 | /* Append to output. */ | |
516 | PUT_32BIT(buf, len); | |
517 | buffer_append(&output, buf, 4); | |
518 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); | |
519 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
520 | buffer_len(&outgoing_packet)); | |
521 | ||
522 | #ifdef PACKET_DEBUG | |
523 | fprintf(stderr, "encrypted: "); | |
524 | buffer_dump(&output); | |
525 | #endif | |
526 | ||
527 | buffer_clear(&outgoing_packet); | |
528 | ||
529 | /* | |
530 | * Note that the packet is now only buffered in output. It won\'t be | |
531 | * actually sent until packet_write_wait or packet_write_poll is | |
532 | * called. | |
533 | */ | |
534 | } | |
535 | ||
536 | void | |
537 | set_newkeys(int mode) | |
538 | { | |
539 | Enc *enc; | |
540 | Mac *mac; | |
541 | Comp *comp; | |
542 | CipherContext *cc; | |
543 | int encrypt; | |
544 | ||
545 | debug("newkeys: mode %d", mode); | |
546 | ||
547 | if (mode == MODE_OUT) { | |
548 | cc = &send_context; | |
549 | encrypt = CIPHER_ENCRYPT; | |
550 | } else { | |
551 | cc = &receive_context; | |
552 | encrypt = CIPHER_DECRYPT; | |
553 | } | |
554 | if (newkeys[mode] != NULL) { | |
555 | debug("newkeys: rekeying"); | |
556 | cipher_cleanup(cc); | |
557 | enc = &newkeys[mode]->enc; | |
558 | mac = &newkeys[mode]->mac; | |
559 | comp = &newkeys[mode]->comp; | |
560 | memset(mac->key, 0, mac->key_len); | |
561 | xfree(enc->name); | |
562 | xfree(enc->iv); | |
563 | xfree(enc->key); | |
564 | xfree(mac->name); | |
565 | xfree(mac->key); | |
566 | xfree(comp->name); | |
567 | xfree(newkeys[mode]); | |
568 | } | |
569 | newkeys[mode] = kex_get_newkeys(mode); | |
570 | if (newkeys[mode] == NULL) | |
571 | fatal("newkeys: no keys for mode %d", mode); | |
572 | enc = &newkeys[mode]->enc; | |
573 | mac = &newkeys[mode]->mac; | |
574 | comp = &newkeys[mode]->comp; | |
575 | if (mac->md != NULL) | |
576 | mac->enabled = 1; | |
577 | DBG(debug("cipher_init_context: %d", mode)); | |
578 | cipher_init(cc, enc->cipher, enc->key, enc->key_len, | |
579 | enc->iv, enc->block_size, encrypt); | |
580 | /* Deleting the keys does not gain extra security */ | |
581 | /* memset(enc->iv, 0, enc->block_size); | |
582 | memset(enc->key, 0, enc->key_len); */ | |
583 | if (comp->type != 0 && comp->enabled == 0) { | |
584 | packet_init_compression(); | |
585 | if (mode == MODE_OUT) | |
586 | buffer_compress_init_send(6); | |
587 | else | |
588 | buffer_compress_init_recv(); | |
589 | comp->enabled = 1; | |
590 | } | |
591 | } | |
592 | ||
593 | /* | |
594 | * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) | |
595 | */ | |
596 | static void | |
597 | packet_send2(void) | |
598 | { | |
599 | u_char type, *cp, *macbuf = NULL; | |
600 | u_char padlen, pad; | |
601 | u_int packet_length = 0; | |
602 | u_int i, len; | |
603 | u_int32_t rand = 0; | |
604 | Enc *enc = NULL; | |
605 | Mac *mac = NULL; | |
606 | Comp *comp = NULL; | |
607 | int block_size; | |
608 | ||
609 | if (newkeys[MODE_OUT] != NULL) { | |
610 | enc = &newkeys[MODE_OUT]->enc; | |
611 | mac = &newkeys[MODE_OUT]->mac; | |
612 | comp = &newkeys[MODE_OUT]->comp; | |
613 | } | |
614 | block_size = enc ? enc->block_size : 8; | |
615 | ||
616 | cp = buffer_ptr(&outgoing_packet); | |
617 | type = cp[5]; | |
618 | ||
619 | #ifdef PACKET_DEBUG | |
620 | fprintf(stderr, "plain: "); | |
621 | buffer_dump(&outgoing_packet); | |
622 | #endif | |
623 | ||
624 | if (comp && comp->enabled) { | |
625 | len = buffer_len(&outgoing_packet); | |
626 | /* skip header, compress only payload */ | |
627 | buffer_consume(&outgoing_packet, 5); | |
628 | buffer_clear(&compression_buffer); | |
629 | buffer_compress(&outgoing_packet, &compression_buffer); | |
630 | buffer_clear(&outgoing_packet); | |
631 | buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); | |
632 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
633 | buffer_len(&compression_buffer)); | |
634 | DBG(debug("compression: raw %d compressed %d", len, | |
635 | buffer_len(&outgoing_packet))); | |
636 | } | |
637 | ||
638 | /* sizeof (packet_len + pad_len + payload) */ | |
639 | len = buffer_len(&outgoing_packet); | |
640 | ||
641 | /* | |
642 | * calc size of padding, alloc space, get random data, | |
643 | * minimum padding is 4 bytes | |
644 | */ | |
645 | padlen = block_size - (len % block_size); | |
646 | if (padlen < 4) | |
647 | padlen += block_size; | |
648 | if (extra_pad) { | |
649 | /* will wrap if extra_pad+padlen > 255 */ | |
650 | extra_pad = roundup(extra_pad, block_size); | |
651 | pad = extra_pad - ((len + padlen) % extra_pad); | |
652 | debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", | |
653 | pad, len, padlen, extra_pad); | |
654 | padlen += pad; | |
655 | extra_pad = 0; | |
656 | } | |
657 | cp = buffer_append_space(&outgoing_packet, padlen); | |
658 | if (enc && !send_context.plaintext) { | |
659 | /* random padding */ | |
660 | for (i = 0; i < padlen; i++) { | |
661 | if (i % 4 == 0) | |
662 | rand = arc4random(); | |
663 | cp[i] = rand & 0xff; | |
664 | rand >>= 8; | |
665 | } | |
666 | } else { | |
667 | /* clear padding */ | |
668 | memset(cp, 0, padlen); | |
669 | } | |
670 | /* packet_length includes payload, padding and padding length field */ | |
671 | packet_length = buffer_len(&outgoing_packet) - 4; | |
672 | cp = buffer_ptr(&outgoing_packet); | |
673 | PUT_32BIT(cp, packet_length); | |
674 | cp[4] = padlen; | |
675 | DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); | |
676 | ||
677 | /* compute MAC over seqnr and packet(length fields, payload, padding) */ | |
678 | if (mac && mac->enabled) { | |
679 | macbuf = mac_compute(mac, send_seqnr, | |
680 | buffer_ptr(&outgoing_packet), | |
681 | buffer_len(&outgoing_packet)); | |
682 | DBG(debug("done calc MAC out #%d", send_seqnr)); | |
683 | } | |
684 | /* encrypt packet and append to output buffer. */ | |
685 | cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); | |
686 | cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
687 | buffer_len(&outgoing_packet)); | |
688 | /* append unencrypted MAC */ | |
689 | if (mac && mac->enabled) | |
690 | buffer_append(&output, (char *)macbuf, mac->mac_len); | |
691 | #ifdef PACKET_DEBUG | |
692 | fprintf(stderr, "encrypted: "); | |
693 | buffer_dump(&output); | |
694 | #endif | |
695 | /* increment sequence number for outgoing packets */ | |
696 | if (++send_seqnr == 0) | |
697 | log("outgoing seqnr wraps around"); | |
698 | buffer_clear(&outgoing_packet); | |
699 | ||
700 | if (type == SSH2_MSG_NEWKEYS) | |
701 | set_newkeys(MODE_OUT); | |
702 | } | |
703 | ||
704 | void | |
705 | packet_send(void) | |
706 | { | |
707 | if (compat20) | |
708 | packet_send2(); | |
709 | else | |
710 | packet_send1(); | |
711 | DBG(debug("packet_send done")); | |
712 | } | |
713 | ||
714 | /* | |
715 | * Waits until a packet has been received, and returns its type. Note that | |
716 | * no other data is processed until this returns, so this function should not | |
717 | * be used during the interactive session. | |
718 | */ | |
719 | ||
720 | int | |
721 | packet_read_seqnr(u_int32_t *seqnr_p) | |
722 | { | |
723 | int type, len; | |
724 | fd_set *setp; | |
725 | char buf[8192]; | |
726 | DBG(debug("packet_read()")); | |
727 | ||
728 | setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * | |
729 | sizeof(fd_mask)); | |
730 | ||
731 | /* Since we are blocking, ensure that all written packets have been sent. */ | |
732 | packet_write_wait(); | |
733 | ||
734 | /* Stay in the loop until we have received a complete packet. */ | |
735 | for (;;) { | |
736 | /* Try to read a packet from the buffer. */ | |
737 | type = packet_read_poll_seqnr(seqnr_p); | |
738 | if (!compat20 && ( | |
739 | type == SSH_SMSG_SUCCESS | |
740 | || type == SSH_SMSG_FAILURE | |
741 | || type == SSH_CMSG_EOF | |
742 | || type == SSH_CMSG_EXIT_CONFIRMATION)) | |
743 | packet_check_eom(); | |
744 | /* If we got a packet, return it. */ | |
745 | if (type != SSH_MSG_NONE) { | |
746 | xfree(setp); | |
747 | return type; | |
748 | } | |
749 | /* | |
750 | * Otherwise, wait for some data to arrive, add it to the | |
751 | * buffer, and try again. | |
752 | */ | |
753 | memset(setp, 0, howmany(connection_in + 1, NFDBITS) * | |
754 | sizeof(fd_mask)); | |
755 | FD_SET(connection_in, setp); | |
756 | ||
757 | /* Wait for some data to arrive. */ | |
758 | while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && | |
759 | (errno == EAGAIN || errno == EINTR)) | |
760 | ; | |
761 | ||
762 | /* Read data from the socket. */ | |
763 | len = read(connection_in, buf, sizeof(buf)); | |
764 | if (len == 0) { | |
765 | log("Connection closed by %.200s", get_remote_ipaddr()); | |
766 | fatal_cleanup(); | |
767 | } | |
768 | if (len < 0) | |
769 | fatal("Read from socket failed: %.100s", strerror(errno)); | |
770 | /* Append it to the buffer. */ | |
771 | packet_process_incoming(buf, len); | |
772 | } | |
773 | /* NOTREACHED */ | |
774 | } | |
775 | ||
776 | int | |
777 | packet_read(void) | |
778 | { | |
779 | return packet_read_seqnr(NULL); | |
780 | } | |
781 | ||
782 | /* | |
783 | * Waits until a packet has been received, verifies that its type matches | |
784 | * that given, and gives a fatal error and exits if there is a mismatch. | |
785 | */ | |
786 | ||
787 | void | |
788 | packet_read_expect(int expected_type) | |
789 | { | |
790 | int type; | |
791 | ||
792 | type = packet_read(); | |
793 | if (type != expected_type) | |
794 | packet_disconnect("Protocol error: expected packet type %d, got %d", | |
795 | expected_type, type); | |
796 | } | |
797 | ||
798 | /* Checks if a full packet is available in the data received so far via | |
799 | * packet_process_incoming. If so, reads the packet; otherwise returns | |
800 | * SSH_MSG_NONE. This does not wait for data from the connection. | |
801 | * | |
802 | * SSH_MSG_DISCONNECT is handled specially here. Also, | |
803 | * SSH_MSG_IGNORE messages are skipped by this function and are never returned | |
804 | * to higher levels. | |
805 | */ | |
806 | ||
807 | static int | |
808 | packet_read_poll1(void) | |
809 | { | |
810 | u_int len, padded_len; | |
811 | u_char *cp, type; | |
812 | u_int checksum, stored_checksum; | |
813 | ||
814 | /* Check if input size is less than minimum packet size. */ | |
815 | if (buffer_len(&input) < 4 + 8) | |
816 | return SSH_MSG_NONE; | |
817 | /* Get length of incoming packet. */ | |
818 | cp = buffer_ptr(&input); | |
819 | len = GET_32BIT(cp); | |
820 | if (len < 1 + 2 + 2 || len > 256 * 1024) | |
821 | packet_disconnect("Bad packet length %d.", len); | |
822 | padded_len = (len + 8) & ~7; | |
823 | ||
824 | /* Check if the packet has been entirely received. */ | |
825 | if (buffer_len(&input) < 4 + padded_len) | |
826 | return SSH_MSG_NONE; | |
827 | ||
828 | /* The entire packet is in buffer. */ | |
829 | ||
830 | /* Consume packet length. */ | |
831 | buffer_consume(&input, 4); | |
832 | ||
833 | /* | |
834 | * Cryptographic attack detector for ssh | |
835 | * (C)1998 CORE-SDI, Buenos Aires Argentina | |
836 | * Ariel Futoransky(futo@core-sdi.com) | |
837 | */ | |
838 | if (!receive_context.plaintext && | |
839 | detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) | |
840 | packet_disconnect("crc32 compensation attack: network attack detected"); | |
841 | ||
842 | /* Decrypt data to incoming_packet. */ | |
843 | buffer_clear(&incoming_packet); | |
844 | cp = buffer_append_space(&incoming_packet, padded_len); | |
845 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); | |
846 | ||
847 | buffer_consume(&input, padded_len); | |
848 | ||
849 | #ifdef PACKET_DEBUG | |
850 | fprintf(stderr, "read_poll plain: "); | |
851 | buffer_dump(&incoming_packet); | |
852 | #endif | |
853 | ||
854 | /* Compute packet checksum. */ | |
855 | checksum = ssh_crc32(buffer_ptr(&incoming_packet), | |
856 | buffer_len(&incoming_packet) - 4); | |
857 | ||
858 | /* Skip padding. */ | |
859 | buffer_consume(&incoming_packet, 8 - len % 8); | |
860 | ||
861 | /* Test check bytes. */ | |
862 | if (len != buffer_len(&incoming_packet)) | |
863 | packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", | |
864 | len, buffer_len(&incoming_packet)); | |
865 | ||
866 | cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; | |
867 | stored_checksum = GET_32BIT(cp); | |
868 | if (checksum != stored_checksum) | |
869 | packet_disconnect("Corrupted check bytes on input."); | |
870 | buffer_consume_end(&incoming_packet, 4); | |
871 | ||
872 | if (packet_compression) { | |
873 | buffer_clear(&compression_buffer); | |
874 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
875 | buffer_clear(&incoming_packet); | |
876 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
877 | buffer_len(&compression_buffer)); | |
878 | } | |
879 | type = buffer_get_char(&incoming_packet); | |
880 | return type; | |
881 | } | |
882 | ||
883 | static int | |
884 | packet_read_poll2(u_int32_t *seqnr_p) | |
885 | { | |
886 | static u_int packet_length = 0; | |
887 | u_int padlen, need; | |
888 | u_char *macbuf, *cp, type; | |
889 | int maclen, block_size; | |
890 | Enc *enc = NULL; | |
891 | Mac *mac = NULL; | |
892 | Comp *comp = NULL; | |
893 | ||
894 | if (newkeys[MODE_IN] != NULL) { | |
895 | enc = &newkeys[MODE_IN]->enc; | |
896 | mac = &newkeys[MODE_IN]->mac; | |
897 | comp = &newkeys[MODE_IN]->comp; | |
898 | } | |
899 | maclen = mac && mac->enabled ? mac->mac_len : 0; | |
900 | block_size = enc ? enc->block_size : 8; | |
901 | ||
902 | if (packet_length == 0) { | |
903 | /* | |
904 | * check if input size is less than the cipher block size, | |
905 | * decrypt first block and extract length of incoming packet | |
906 | */ | |
907 | if (buffer_len(&input) < block_size) | |
908 | return SSH_MSG_NONE; | |
909 | buffer_clear(&incoming_packet); | |
910 | cp = buffer_append_space(&incoming_packet, block_size); | |
911 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), | |
912 | block_size); | |
913 | cp = buffer_ptr(&incoming_packet); | |
914 | packet_length = GET_32BIT(cp); | |
915 | if (packet_length < 1 + 4 || packet_length > 256 * 1024) { | |
916 | buffer_dump(&incoming_packet); | |
917 | packet_disconnect("Bad packet length %d.", packet_length); | |
918 | } | |
919 | DBG(debug("input: packet len %d", packet_length+4)); | |
920 | buffer_consume(&input, block_size); | |
921 | } | |
922 | /* we have a partial packet of block_size bytes */ | |
923 | need = 4 + packet_length - block_size; | |
924 | DBG(debug("partial packet %d, need %d, maclen %d", block_size, | |
925 | need, maclen)); | |
926 | if (need % block_size != 0) | |
927 | fatal("padding error: need %d block %d mod %d", | |
928 | need, block_size, need % block_size); | |
929 | /* | |
930 | * check if the entire packet has been received and | |
931 | * decrypt into incoming_packet | |
932 | */ | |
933 | if (buffer_len(&input) < need + maclen) | |
934 | return SSH_MSG_NONE; | |
935 | #ifdef PACKET_DEBUG | |
936 | fprintf(stderr, "read_poll enc/full: "); | |
937 | buffer_dump(&input); | |
938 | #endif | |
939 | cp = buffer_append_space(&incoming_packet, need); | |
940 | cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); | |
941 | buffer_consume(&input, need); | |
942 | /* | |
943 | * compute MAC over seqnr and packet, | |
944 | * increment sequence number for incoming packet | |
945 | */ | |
946 | if (mac && mac->enabled) { | |
947 | macbuf = mac_compute(mac, read_seqnr, | |
948 | buffer_ptr(&incoming_packet), | |
949 | buffer_len(&incoming_packet)); | |
950 | if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) | |
951 | packet_disconnect("Corrupted MAC on input."); | |
952 | DBG(debug("MAC #%d ok", read_seqnr)); | |
953 | buffer_consume(&input, mac->mac_len); | |
954 | } | |
955 | if (seqnr_p != NULL) | |
956 | *seqnr_p = read_seqnr; | |
957 | if (++read_seqnr == 0) | |
958 | log("incoming seqnr wraps around"); | |
959 | ||
960 | /* get padlen */ | |
961 | cp = buffer_ptr(&incoming_packet); | |
962 | padlen = cp[4]; | |
963 | DBG(debug("input: padlen %d", padlen)); | |
964 | if (padlen < 4) | |
965 | packet_disconnect("Corrupted padlen %d on input.", padlen); | |
966 | ||
967 | /* skip packet size + padlen, discard padding */ | |
968 | buffer_consume(&incoming_packet, 4 + 1); | |
969 | buffer_consume_end(&incoming_packet, padlen); | |
970 | ||
971 | DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); | |
972 | if (comp && comp->enabled) { | |
973 | buffer_clear(&compression_buffer); | |
974 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
975 | buffer_clear(&incoming_packet); | |
976 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
977 | buffer_len(&compression_buffer)); | |
978 | DBG(debug("input: len after de-compress %d", buffer_len(&incoming_packet))); | |
979 | } | |
980 | /* | |
981 | * get packet type, implies consume. | |
982 | * return length of payload (without type field) | |
983 | */ | |
984 | type = buffer_get_char(&incoming_packet); | |
985 | if (type == SSH2_MSG_NEWKEYS) | |
986 | set_newkeys(MODE_IN); | |
987 | #ifdef PACKET_DEBUG | |
988 | fprintf(stderr, "read/plain[%d]:\r\n", type); | |
989 | buffer_dump(&incoming_packet); | |
990 | #endif | |
991 | /* reset for next packet */ | |
992 | packet_length = 0; | |
993 | return type; | |
994 | } | |
995 | ||
996 | int | |
997 | packet_read_poll_seqnr(u_int32_t *seqnr_p) | |
998 | { | |
999 | int reason, seqnr; | |
1000 | u_char type; | |
1001 | char *msg; | |
1002 | ||
1003 | for (;;) { | |
1004 | if (compat20) { | |
1005 | type = packet_read_poll2(seqnr_p); | |
1006 | if (type) | |
1007 | DBG(debug("received packet type %d", type)); | |
1008 | switch (type) { | |
1009 | case SSH2_MSG_IGNORE: | |
1010 | break; | |
1011 | case SSH2_MSG_DEBUG: | |
1012 | packet_get_char(); | |
1013 | msg = packet_get_string(NULL); | |
1014 | debug("Remote: %.900s", msg); | |
1015 | xfree(msg); | |
1016 | msg = packet_get_string(NULL); | |
1017 | xfree(msg); | |
1018 | break; | |
1019 | case SSH2_MSG_DISCONNECT: | |
1020 | reason = packet_get_int(); | |
1021 | msg = packet_get_string(NULL); | |
1022 | log("Received disconnect from %s: %d: %.400s", get_remote_ipaddr(), | |
1023 | reason, msg); | |
1024 | xfree(msg); | |
1025 | fatal_cleanup(); | |
1026 | break; | |
1027 | case SSH2_MSG_UNIMPLEMENTED: | |
1028 | seqnr = packet_get_int(); | |
1029 | debug("Received SSH2_MSG_UNIMPLEMENTED for %d", seqnr); | |
1030 | break; | |
1031 | default: | |
1032 | return type; | |
1033 | break; | |
1034 | } | |
1035 | } else { | |
1036 | type = packet_read_poll1(); | |
1037 | switch (type) { | |
1038 | case SSH_MSG_IGNORE: | |
1039 | break; | |
1040 | case SSH_MSG_DEBUG: | |
1041 | msg = packet_get_string(NULL); | |
1042 | debug("Remote: %.900s", msg); | |
1043 | xfree(msg); | |
1044 | break; | |
1045 | case SSH_MSG_DISCONNECT: | |
1046 | msg = packet_get_string(NULL); | |
1047 | log("Received disconnect from %s: %.400s", get_remote_ipaddr(), | |
1048 | msg); | |
1049 | fatal_cleanup(); | |
1050 | xfree(msg); | |
1051 | break; | |
1052 | default: | |
1053 | if (type) | |
1054 | DBG(debug("received packet type %d", type)); | |
1055 | return type; | |
1056 | break; | |
1057 | } | |
1058 | } | |
1059 | } | |
1060 | } | |
1061 | ||
1062 | int | |
1063 | packet_read_poll(void) | |
1064 | { | |
1065 | return packet_read_poll_seqnr(NULL); | |
1066 | } | |
1067 | ||
1068 | /* | |
1069 | * Buffers the given amount of input characters. This is intended to be used | |
1070 | * together with packet_read_poll. | |
1071 | */ | |
1072 | ||
1073 | void | |
1074 | packet_process_incoming(const char *buf, u_int len) | |
1075 | { | |
1076 | buffer_append(&input, buf, len); | |
1077 | } | |
1078 | ||
1079 | /* Returns a character from the packet. */ | |
1080 | ||
1081 | u_int | |
1082 | packet_get_char(void) | |
1083 | { | |
1084 | char ch; | |
1085 | buffer_get(&incoming_packet, &ch, 1); | |
1086 | return (u_char) ch; | |
1087 | } | |
1088 | ||
1089 | /* Returns an integer from the packet data. */ | |
1090 | ||
1091 | u_int | |
1092 | packet_get_int(void) | |
1093 | { | |
1094 | return buffer_get_int(&incoming_packet); | |
1095 | } | |
1096 | ||
1097 | /* | |
1098 | * Returns an arbitrary precision integer from the packet data. The integer | |
1099 | * must have been initialized before this call. | |
1100 | */ | |
1101 | ||
1102 | void | |
1103 | packet_get_bignum(BIGNUM * value) | |
1104 | { | |
1105 | buffer_get_bignum(&incoming_packet, value); | |
1106 | } | |
1107 | ||
1108 | void | |
1109 | packet_get_bignum2(BIGNUM * value) | |
1110 | { | |
1111 | buffer_get_bignum2(&incoming_packet, value); | |
1112 | } | |
1113 | ||
1114 | void * | |
1115 | packet_get_raw(int *length_ptr) | |
1116 | { | |
1117 | int bytes = buffer_len(&incoming_packet); | |
1118 | if (length_ptr != NULL) | |
1119 | *length_ptr = bytes; | |
1120 | return buffer_ptr(&incoming_packet); | |
1121 | } | |
1122 | ||
1123 | int | |
1124 | packet_remaining(void) | |
1125 | { | |
1126 | return buffer_len(&incoming_packet); | |
1127 | } | |
1128 | ||
1129 | /* | |
1130 | * Returns a string from the packet data. The string is allocated using | |
1131 | * xmalloc; it is the responsibility of the calling program to free it when | |
1132 | * no longer needed. The length_ptr argument may be NULL, or point to an | |
1133 | * integer into which the length of the string is stored. | |
1134 | */ | |
1135 | ||
1136 | void * | |
1137 | packet_get_string(u_int *length_ptr) | |
1138 | { | |
1139 | return buffer_get_string(&incoming_packet, length_ptr); | |
1140 | } | |
1141 | ||
1142 | /* | |
1143 | * Sends a diagnostic message from the server to the client. This message | |
1144 | * can be sent at any time (but not while constructing another message). The | |
1145 | * message is printed immediately, but only if the client is being executed | |
1146 | * in verbose mode. These messages are primarily intended to ease debugging | |
1147 | * authentication problems. The length of the formatted message must not | |
1148 | * exceed 1024 bytes. This will automatically call packet_write_wait. | |
1149 | */ | |
1150 | ||
1151 | void | |
1152 | packet_send_debug(const char *fmt,...) | |
1153 | { | |
1154 | char buf[1024]; | |
1155 | va_list args; | |
1156 | ||
1157 | if (compat20 && (datafellows & SSH_BUG_DEBUG)) | |
1158 | return; | |
1159 | ||
1160 | va_start(args, fmt); | |
1161 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1162 | va_end(args); | |
1163 | ||
1164 | if (compat20) { | |
1165 | packet_start(SSH2_MSG_DEBUG); | |
1166 | packet_put_char(0); /* bool: always display */ | |
1167 | packet_put_cstring(buf); | |
1168 | packet_put_cstring(""); | |
1169 | } else { | |
1170 | packet_start(SSH_MSG_DEBUG); | |
1171 | packet_put_cstring(buf); | |
1172 | } | |
1173 | packet_send(); | |
1174 | packet_write_wait(); | |
1175 | } | |
1176 | ||
1177 | /* | |
1178 | * Logs the error plus constructs and sends a disconnect packet, closes the | |
1179 | * connection, and exits. This function never returns. The error message | |
1180 | * should not contain a newline. The length of the formatted message must | |
1181 | * not exceed 1024 bytes. | |
1182 | */ | |
1183 | ||
1184 | void | |
1185 | packet_disconnect(const char *fmt,...) | |
1186 | { | |
1187 | char buf[1024]; | |
1188 | va_list args; | |
1189 | static int disconnecting = 0; | |
1190 | if (disconnecting) /* Guard against recursive invocations. */ | |
1191 | fatal("packet_disconnect called recursively."); | |
1192 | disconnecting = 1; | |
1193 | ||
1194 | /* | |
1195 | * Format the message. Note that the caller must make sure the | |
1196 | * message is of limited size. | |
1197 | */ | |
1198 | va_start(args, fmt); | |
1199 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1200 | va_end(args); | |
1201 | ||
1202 | /* Send the disconnect message to the other side, and wait for it to get sent. */ | |
1203 | if (compat20) { | |
1204 | packet_start(SSH2_MSG_DISCONNECT); | |
1205 | packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); | |
1206 | packet_put_cstring(buf); | |
1207 | packet_put_cstring(""); | |
1208 | } else { | |
1209 | packet_start(SSH_MSG_DISCONNECT); | |
1210 | packet_put_cstring(buf); | |
1211 | } | |
1212 | packet_send(); | |
1213 | packet_write_wait(); | |
1214 | ||
1215 | /* Stop listening for connections. */ | |
1216 | channel_close_all(); | |
1217 | ||
1218 | /* Close the connection. */ | |
1219 | packet_close(); | |
1220 | ||
1221 | /* Display the error locally and exit. */ | |
1222 | log("Disconnecting: %.100s", buf); | |
1223 | fatal_cleanup(); | |
1224 | } | |
1225 | ||
1226 | /* Checks if there is any buffered output, and tries to write some of the output. */ | |
1227 | ||
1228 | void | |
1229 | packet_write_poll(void) | |
1230 | { | |
1231 | int len = buffer_len(&output); | |
1232 | if (len > 0) { | |
1233 | len = write(connection_out, buffer_ptr(&output), len); | |
1234 | if (len <= 0) { | |
1235 | if (errno == EAGAIN) | |
1236 | return; | |
1237 | else | |
1238 | fatal("Write failed: %.100s", strerror(errno)); | |
1239 | } | |
1240 | buffer_consume(&output, len); | |
1241 | } | |
1242 | } | |
1243 | ||
1244 | /* | |
1245 | * Calls packet_write_poll repeatedly until all pending output data has been | |
1246 | * written. | |
1247 | */ | |
1248 | ||
1249 | void | |
1250 | packet_write_wait(void) | |
1251 | { | |
1252 | fd_set *setp; | |
1253 | ||
1254 | setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * | |
1255 | sizeof(fd_mask)); | |
1256 | packet_write_poll(); | |
1257 | while (packet_have_data_to_write()) { | |
1258 | memset(setp, 0, howmany(connection_out + 1, NFDBITS) * | |
1259 | sizeof(fd_mask)); | |
1260 | FD_SET(connection_out, setp); | |
1261 | while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && | |
1262 | (errno == EAGAIN || errno == EINTR)) | |
1263 | ; | |
1264 | packet_write_poll(); | |
1265 | } | |
1266 | xfree(setp); | |
1267 | } | |
1268 | ||
1269 | /* Returns true if there is buffered data to write to the connection. */ | |
1270 | ||
1271 | int | |
1272 | packet_have_data_to_write(void) | |
1273 | { | |
1274 | return buffer_len(&output) != 0; | |
1275 | } | |
1276 | ||
1277 | /* Returns true if there is not too much data to write to the connection. */ | |
1278 | ||
1279 | int | |
1280 | packet_not_very_much_data_to_write(void) | |
1281 | { | |
1282 | if (interactive_mode) | |
1283 | return buffer_len(&output) < 16384; | |
1284 | else | |
1285 | return buffer_len(&output) < 128 * 1024; | |
1286 | } | |
1287 | ||
1288 | /* Informs that the current session is interactive. Sets IP flags for that. */ | |
1289 | ||
1290 | void | |
1291 | packet_set_interactive(int interactive) | |
1292 | { | |
1293 | static int called = 0; | |
1294 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) | |
1295 | int lowdelay = IPTOS_LOWDELAY; | |
1296 | int throughput = IPTOS_THROUGHPUT; | |
1297 | #endif | |
1298 | ||
1299 | if (called) | |
1300 | return; | |
1301 | called = 1; | |
1302 | ||
1303 | /* Record that we are in interactive mode. */ | |
1304 | interactive_mode = interactive; | |
1305 | ||
1306 | /* Only set socket options if using a socket. */ | |
1307 | if (!packet_connection_is_on_socket()) | |
1308 | return; | |
1309 | /* | |
1310 | * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only | |
1311 | */ | |
1312 | if (interactive) { | |
1313 | /* | |
1314 | * Set IP options for an interactive connection. Use | |
1315 | * IPTOS_LOWDELAY and TCP_NODELAY. | |
1316 | */ | |
1317 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) | |
1318 | if (packet_connection_is_ipv4()) { | |
1319 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, | |
1320 | &lowdelay, sizeof(lowdelay)) < 0) | |
1321 | error("setsockopt IPTOS_LOWDELAY: %.100s", | |
1322 | strerror(errno)); | |
1323 | } | |
1324 | #endif | |
1325 | set_nodelay(connection_in); | |
1326 | } else if (packet_connection_is_ipv4()) { | |
1327 | /* | |
1328 | * Set IP options for a non-interactive connection. Use | |
1329 | * IPTOS_THROUGHPUT. | |
1330 | */ | |
1331 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) | |
1332 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &throughput, | |
1333 | sizeof(throughput)) < 0) | |
1334 | error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); | |
1335 | #endif | |
1336 | } | |
1337 | } | |
1338 | ||
1339 | /* Returns true if the current connection is interactive. */ | |
1340 | ||
1341 | int | |
1342 | packet_is_interactive(void) | |
1343 | { | |
1344 | return interactive_mode; | |
1345 | } | |
1346 | ||
1347 | int | |
1348 | packet_set_maxsize(int s) | |
1349 | { | |
1350 | static int called = 0; | |
1351 | if (called) { | |
1352 | log("packet_set_maxsize: called twice: old %d new %d", | |
1353 | max_packet_size, s); | |
1354 | return -1; | |
1355 | } | |
1356 | if (s < 4 * 1024 || s > 1024 * 1024) { | |
1357 | log("packet_set_maxsize: bad size %d", s); | |
1358 | return -1; | |
1359 | } | |
1360 | called = 1; | |
1361 | debug("packet_set_maxsize: setting to %d", s); | |
1362 | max_packet_size = s; | |
1363 | return s; | |
1364 | } | |
1365 | ||
1366 | /* roundup current message to pad bytes */ | |
1367 | void | |
1368 | packet_add_padding(u_char pad) | |
1369 | { | |
1370 | extra_pad = pad; | |
1371 | } | |
1372 | ||
1373 | /* | |
1374 | * 9.2. Ignored Data Message | |
1375 | * | |
1376 | * byte SSH_MSG_IGNORE | |
1377 | * string data | |
1378 | * | |
1379 | * All implementations MUST understand (and ignore) this message at any | |
1380 | * time (after receiving the protocol version). No implementation is | |
1381 | * required to send them. This message can be used as an additional | |
1382 | * protection measure against advanced traffic analysis techniques. | |
1383 | */ | |
1384 | void | |
1385 | packet_send_ignore(int nbytes) | |
1386 | { | |
1387 | u_int32_t rand = 0; | |
1388 | int i; | |
1389 | ||
1390 | packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); | |
1391 | packet_put_int(nbytes); | |
1392 | for (i = 0; i < nbytes; i++) { | |
1393 | if (i % 4 == 0) | |
1394 | rand = arc4random(); | |
1395 | packet_put_char(rand & 0xff); | |
1396 | rand >>= 8; | |
1397 | } | |
1398 | } |