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 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
40 * Use is subject to license terms.
41 */
42
43 /* $OpenBSD: packet.c,v 1.148 2007/06/07 19:37:34 pvalchev Exp $ */
44
45 #include "includes.h"
46
47 #include "sys-queue.h"
48 #include "xmalloc.h"
49 #include "buffer.h"
50 #include "packet.h"
51 #include "bufaux.h"
52 #include "crc32.h"
53 #include "getput.h"
54 #include "compress.h"
55 #include "deattack.h"
56 #include "channels.h"
57 #include "compat.h"
58 #include "ssh1.h"
59 #include "ssh2.h"
60 #include "cipher.h"
61 #include "kex.h"
62 #include "mac.h"
63 #include "log.h"
64 #include "canohost.h"
65 #include "misc.h"
66 #include "ssh.h"
67 #include "engine.h"
68
69 /* PKCS#11 engine */
70 ENGINE *e;
71
72 #ifdef ALTPRIVSEP
73 static int packet_server = 0;
74 static int packet_monitor = 0;
75 #endif /* ALTPRIVSEP */
76
77 #ifdef PACKET_DEBUG
78 #define DBG(x) x
79 #else
80 #define DBG(x)
81 #endif
82
83 static void packet_send2(void);
84
85 /*
86 * This variable contains the file descriptors used for communicating with
87 * the other side. connection_in is used for reading; connection_out for
88 * writing. These can be the same descriptor, in which case it is assumed to
89 * be a socket.
90 */
91 static int connection_in = -1;
92 static int connection_out = -1;
93
94 /* Protocol flags for the remote side. */
95 static u_int remote_protocol_flags = 0;
96
97 /* Encryption context for receiving data. This is only used for decryption. */
98 static CipherContext receive_context;
99
100 /* Encryption context for sending data. This is only used for encryption. */
101 static CipherContext send_context;
102
103 /* Buffer for raw input data from the socket. */
104 Buffer input;
105
106 /* Buffer for raw output data going to the socket. */
107 Buffer output;
108
109 /* Buffer for the partial outgoing packet being constructed. */
110 static Buffer outgoing_packet;
111
112 /* Buffer for the incoming packet currently being processed. */
113 static Buffer incoming_packet;
114
115 /* Scratch buffer for packet compression/decompression. */
116 static Buffer compression_buffer;
117 static int compression_buffer_ready = 0;
118
119 /* Flag indicating whether packet compression/decompression is enabled. */
120 static int packet_compression = 0;
121
122 /* default maximum packet size */
123 int max_packet_size = 32768;
124
125 /* Flag indicating whether this module has been initialized. */
126 static int initialized = 0;
127
128 /* Set to true if the connection is interactive. */
129 static int interactive_mode = 0;
130
131 /* Session key information for Encryption and MAC */
132 Newkeys *newkeys[MODE_MAX];
133 static struct packet_state {
134 u_int32_t seqnr;
135 u_int32_t packets;
136 u_int64_t blocks;
137 } p_read, p_send;
138
139 static u_int64_t max_blocks_in, max_blocks_out;
140 static u_int32_t rekey_limit;
141
142 /* Session key for protocol v1 */
143 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
144 static u_int ssh1_keylen;
145
146 /* roundup current message to extra_pad bytes */
147 static u_char extra_pad = 0;
148
149 struct packet {
150 TAILQ_ENTRY(packet) next;
151 u_char type;
152 Buffer payload;
153 };
154 TAILQ_HEAD(, packet) outgoing;
155
156 /*
157 * Part of what -f option and ~& escape sequence do in the client is that they
158 * will force it to daemonize itself. Due to the fork safety rules inherent in
159 * any PKCS#11 environment, if the engine is used we must do a key re-exchange
160 * before forking a child to negotiate the new keys. Those keys will be used to
161 * inicialize the new crypto contexts. This involves finishing the engine in the
162 * parent and reinitializing it again in both processes after fork() returns.
163 * This approach also leaves protocol 1 out since it doesn't support rekeying.
164 */
165 int will_daemonize;
166
167 #ifdef PACKET_DEBUG
168 /* This function dumps data onto stderr. This is for debugging only. */
169 void
170 data_dump(void *data, u_int len)
171 {
172 Buffer buf;
173
174 buffer_init(&buf);
175 buffer_append(&buf, data, len);
176 buffer_dump(&buf);
177 buffer_free(&buf);
178 }
179 #endif
180
181 /*
182 * Sets the descriptors used for communication. Disables encryption until
183 * packet_set_encryption_key is called.
184 */
185 void
186 packet_set_connection(int fd_in, int fd_out)
187 {
188 Cipher *none = cipher_by_name("none");
189
190 if (none == NULL)
191 fatal("packet_set_connection: cannot load cipher 'none'");
192 connection_in = fd_in;
193 connection_out = fd_out;
194 cipher_init(&send_context, none, (unsigned char *) "", 0, NULL, 0, CIPHER_ENCRYPT);
195 cipher_init(&receive_context, none, (unsigned char *) "", 0, NULL, 0, CIPHER_DECRYPT);
196 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
197 if (!initialized) {
198 initialized = 1;
199 buffer_init(&input);
200 buffer_init(&output);
201 buffer_init(&outgoing_packet);
202 buffer_init(&incoming_packet);
203 TAILQ_INIT(&outgoing);
204 } else {
205 buffer_clear(&input);
206 buffer_clear(&output);
207 buffer_clear(&outgoing_packet);
208 buffer_clear(&incoming_packet);
209 }
210
211 /*
212 * Prime the cache for get_remote_ipaddr() while we have a
213 * socket on which to do a getpeername().
214 */
215 (void) get_remote_ipaddr();
216
217 /* Kludge: arrange the close function to be called from fatal(). */
218 fatal_add_cleanup((void (*) (void *)) packet_close, NULL);
219 }
220
221 /* Returns 1 if remote host is connected via socket, 0 if not. */
222
223 int
224 packet_connection_is_on_socket(void)
225 {
226 struct sockaddr_storage from, to;
227 socklen_t fromlen, tolen;
228
229 /* filedescriptors in and out are the same, so it's a socket */
230 if (connection_in != -1 && connection_in == connection_out)
231 return 1;
232 fromlen = sizeof(from);
233 memset(&from, 0, sizeof(from));
234 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
235 return 0;
236 tolen = sizeof(to);
237 memset(&to, 0, sizeof(to));
238 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
239 return 0;
240 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
241 return 0;
242 if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
243 return 0;
244 return 1;
245 }
246
247 /* returns 1 if connection is via ipv4 */
248
249 int
250 packet_connection_is_ipv4(void)
251 {
252 struct sockaddr_storage to;
253 socklen_t tolen = sizeof(to);
254
255 memset(&to, 0, sizeof(to));
256 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
257 return 0;
258 if (to.ss_family == AF_INET)
259 return 1;
260 #ifdef IPV4_IN_IPV6
261 if (to.ss_family == AF_INET6 &&
262 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
263 return 1;
264 #endif
265 return 0;
266 }
267
268 /* Sets the connection into non-blocking mode. */
269
270 void
271 packet_set_nonblocking(void)
272 {
273 /* Set the socket into non-blocking mode. */
274 if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0)
275 error("fcntl O_NONBLOCK: %.100s", strerror(errno));
276
277 if (connection_out != connection_in) {
278 if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0)
279 error("fcntl O_NONBLOCK: %.100s", strerror(errno));
280 }
281 }
282
283 /* Returns the socket used for reading. */
284
285 int
286 packet_get_connection_in(void)
287 {
288 return connection_in;
289 }
290
291 /* Returns the descriptor used for writing. */
292
293 int
294 packet_get_connection_out(void)
295 {
296 return connection_out;
297 }
298
299 /* Closes the connection and clears and frees internal data structures. */
300
301 void
302 packet_close(void)
303 {
304 if (!initialized)
305 return;
306 initialized = 0;
307 if (connection_in == connection_out) {
308 shutdown(connection_out, SHUT_RDWR);
309 close(connection_out);
310 } else {
311 close(connection_in);
312 close(connection_out);
313 }
314 buffer_free(&input);
315 buffer_free(&output);
316 buffer_free(&outgoing_packet);
317 buffer_free(&incoming_packet);
318 if (compression_buffer_ready) {
319 buffer_free(&compression_buffer);
320 buffer_compress_uninit();
321 compression_buffer_ready = 0;
322 }
323 cipher_cleanup(&send_context);
324 cipher_cleanup(&receive_context);
325 }
326
327 /* Sets remote side protocol flags. */
328
329 void
330 packet_set_protocol_flags(u_int protocol_flags)
331 {
332 remote_protocol_flags = protocol_flags;
333 }
334
335 /* Returns the remote protocol flags set earlier by the above function. */
336
337 u_int
338 packet_get_protocol_flags(void)
339 {
340 return remote_protocol_flags;
341 }
342
343 /*
344 * Starts packet compression from the next packet on in both directions.
345 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
346 */
347
348 static void
349 packet_init_compression(void)
350 {
351 if (compression_buffer_ready == 1)
352 return;
353 compression_buffer_ready = 1;
354 buffer_init(&compression_buffer);
355 }
356
357 void
358 packet_start_compression(int level)
359 {
360 #ifdef ALTPRIVSEP
361 /* shouldn't happen! */
362 if (packet_monitor)
363 fatal("INTERNAL ERROR: The monitor cannot compress.");
364 #endif /* ALTPRIVSEP */
365
366 if (packet_compression && !compat20)
367 fatal("Compression already enabled.");
368 packet_compression = 1;
369 packet_init_compression();
370 buffer_compress_init_send(level);
371 buffer_compress_init_recv();
372 }
373
374 /*
375 * Causes any further packets to be encrypted using the given key. The same
376 * key is used for both sending and reception. However, both directions are
377 * encrypted independently of each other.
378 */
379
380 void
381 packet_set_encryption_key(const u_char *key, u_int keylen,
382 int number)
383 {
384 Cipher *cipher = cipher_by_number(number);
385
386 if (cipher == NULL)
387 fatal("packet_set_encryption_key: unknown cipher number %d", number);
388 if (keylen < 20)
389 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
390 if (keylen > SSH_SESSION_KEY_LENGTH)
391 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
392 memcpy(ssh1_key, key, keylen);
393 ssh1_keylen = keylen;
394 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT);
395 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT);
396 }
397
398 u_int
399 packet_get_encryption_key(u_char *key)
400 {
401 if (key == NULL)
402 return (ssh1_keylen);
403 memcpy(key, ssh1_key, ssh1_keylen);
404 return (ssh1_keylen);
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
428 buffer_append(&outgoing_packet, &ch, 1);
429 }
430
431 void
432 packet_put_int(u_int value)
433 {
434 buffer_put_int(&outgoing_packet, value);
435 }
436
437 void
438 packet_put_string(const void *buf, u_int len)
439 {
440 buffer_put_string(&outgoing_packet, buf, len);
441 }
442
443 void
444 packet_put_cstring(const char *str)
445 {
446 buffer_put_cstring(&outgoing_packet, str);
447 }
448
449 void
450 packet_put_utf8_cstring(const char *str)
451 {
452 if (datafellows & SSH_BUG_STRING_ENCODING)
453 buffer_put_cstring(&outgoing_packet, str);
454 else
455 buffer_put_utf8_cstring(&outgoing_packet, str);
456 }
457
458 void
459 packet_put_utf8_string(const char *str, uint_t len)
460 {
461 if (datafellows & SSH_BUG_STRING_ENCODING)
462 buffer_put_string(&outgoing_packet, str, len);
463 else
464 buffer_put_utf8_string(&outgoing_packet, str, len);
465 }
466
467 void
468 packet_put_raw(const void *buf, u_int len)
469 {
470 buffer_append(&outgoing_packet, buf, len);
471 }
472
473 void
474 packet_put_bignum(BIGNUM * value)
475 {
476 buffer_put_bignum(&outgoing_packet, value);
477 }
478
479 void
480 packet_put_bignum2(BIGNUM * value)
481 {
482 buffer_put_bignum2(&outgoing_packet, value);
483 }
484
485 /*
486 * Finalizes and sends the packet. If the encryption key has been set,
487 * encrypts the packet before sending.
488 */
489
490 static void
491 packet_send1(void)
492 {
493 u_char buf[8], *cp;
494 int i, padding, len;
495 u_int checksum;
496 u_int32_t rnd = 0;
497
498 /*
499 * If using packet compression, compress the payload of the outgoing
500 * packet.
501 */
502 if (packet_compression) {
503 buffer_clear(&compression_buffer);
504 /* Skip padding. */
505 buffer_consume(&outgoing_packet, 8);
506 /* padding */
507 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
508 buffer_compress(&outgoing_packet, &compression_buffer);
509 buffer_clear(&outgoing_packet);
510 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
511 buffer_len(&compression_buffer));
512 }
513 /* Compute packet length without padding (add checksum, remove padding). */
514 len = buffer_len(&outgoing_packet) + 4 - 8;
515
516 /* Insert padding. Initialized to zero in packet_start1() */
517 padding = 8 - len % 8;
518 if (!send_context.plaintext) {
519 cp = buffer_ptr(&outgoing_packet);
520 for (i = 0; i < padding; i++) {
521 if (i % 4 == 0)
522 rnd = arc4random();
523 cp[7 - i] = rnd & 0xff;
524 rnd >>= 8;
525 }
526 }
527 buffer_consume(&outgoing_packet, 8 - padding);
528
529 /* Add check bytes. */
530 checksum = ssh_crc32(buffer_ptr(&outgoing_packet),
531 buffer_len(&outgoing_packet));
532 PUT_32BIT(buf, checksum);
533 buffer_append(&outgoing_packet, buf, 4);
534
535 #ifdef PACKET_DEBUG
536 fprintf(stderr, "packet_send plain: ");
537 buffer_dump(&outgoing_packet);
538 #endif
539
540 /* Append to output. */
541 PUT_32BIT(buf, len);
542 buffer_append(&output, buf, 4);
543 cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
544 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
545 buffer_len(&outgoing_packet));
546
547 #ifdef PACKET_DEBUG
548 debug("encrypted output queue now contains (%d bytes):\n",
549 buffer_len(&output));
550 buffer_dump(&output);
551 #endif
552
553 buffer_clear(&outgoing_packet);
554
555 /*
556 * Note that the packet is now only buffered in output. It won\'t be
557 * actually sent until packet_write_wait or packet_write_poll is
558 * called.
559 */
560 }
561
562 void
563 set_newkeys(int mode)
564 {
565 Enc *enc;
566 Mac *mac;
567 Comp *comp;
568 CipherContext *cc;
569 u_int64_t *max_blocks;
570 int crypt_type;
571
572 debug2("set_newkeys: mode %d", mode);
573
574 if (mode == MODE_OUT) {
575 cc = &send_context;
576 crypt_type = CIPHER_ENCRYPT;
577 p_send.packets = p_send.blocks = 0;
578 max_blocks = &max_blocks_out;
579 } else {
580 cc = &receive_context;
581 crypt_type = CIPHER_DECRYPT;
582 p_read.packets = p_read.blocks = 0;
583 max_blocks = &max_blocks_in;
584 }
585
586 debug("set_newkeys: setting new keys for '%s' mode",
587 mode == MODE_IN ? "in" : "out");
588
589 if (newkeys[mode] != NULL) {
590 cipher_cleanup(cc);
591 free_keys(newkeys[mode]);
592 }
593
594 newkeys[mode] = kex_get_newkeys(mode);
595 if (newkeys[mode] == NULL)
596 fatal("newkeys: no keys for mode %d", mode);
597 enc = &newkeys[mode]->enc;
598 mac = &newkeys[mode]->mac;
599 comp = &newkeys[mode]->comp;
600 if (mac_init(mac) == 0)
601 mac->enabled = 1;
602 #ifdef PACKET_DEBUG
603 debug("new encryption key:\n");
604 data_dump(enc->key, enc->key_len);
605 debug("new encryption IV:\n");
606 data_dump(enc->iv, enc->block_size);
607 debug("new MAC key:\n");
608 data_dump(mac->key, mac->key_len);
609 #endif
610 cipher_init(cc, enc->cipher, enc->key, enc->key_len,
611 enc->iv, enc->block_size, crypt_type);
612 /* Deleting the keys does not gain extra security */
613 /* memset(enc->iv, 0, enc->block_size);
614 memset(enc->key, 0, enc->key_len); */
615 if (comp->type != 0 && comp->enabled == 0) {
616 packet_init_compression();
617 if (mode == MODE_OUT)
618 buffer_compress_init_send(6);
619 else
620 buffer_compress_init_recv();
621 comp->enabled = 1;
622 }
623
624 /*
625 * In accordance to the RFCs listed below we enforce the key
626 * re-exchange for:
627 *
628 * - every 1GB of transmitted data if the selected cipher block size
629 * is less than 16 bytes (3DES, Blowfish)
630 * - every 2^(2*B) cipher blocks transmitted (B is block size in bytes)
631 * if the cipher block size is greater than or equal to 16 bytes (AES)
632 * - and we never send more than 2^32 SSH packets using the same keys.
633 * The recommendation of 2^31 packets is not enforced here but in
634 * packet_need_rekeying(). There is also a hard check in
635 * packet_send2_wrapped() that we don't send more than 2^32 packets.
636 *
637 * Note that if the SSH_BUG_NOREKEY compatibility flag is set then no
638 * automatic rekeying is performed nor do we enforce the 3rd rule.
639 * This means that we can be always forced by the opposite side to never
640 * initiate automatic key re-exchange. This might change in the future.
641 *
642 * The RekeyLimit option keyword may only enforce more frequent key
643 * renegotiation, never less. For more information on key renegotiation,
644 * see:
645 *
646 * - RFC 4253 (SSH Transport Layer Protocol), section "9. Key
647 * Re-Exchange"
648 * - RFC 4344 (SSH Transport Layer Encryption Modes), sections "3.
649 * Rekeying" and "6.1 Rekeying Considerations"
650 */
651 if (enc->block_size >= 16)
652 *max_blocks = (u_int64_t)1 << (enc->block_size * 2);
653 else
654 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
655
656 if (rekey_limit)
657 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
658 }
659
660 void
661 free_keys(Newkeys *keys)
662 {
663 Enc *enc;
664 Mac *mac;
665 Comp *comp;
666
667 enc = &keys->enc;
668 mac = &keys->mac;
669 comp = &keys->comp;
670 xfree(enc->name);
671 xfree(enc->iv);
672 xfree(enc->key);
673
674 memset(mac->key, 0, mac->key_len);
675 xfree(mac->key);
676 xfree(mac->name);
677 mac_clear(mac);
678
679 xfree(comp->name);
680 xfree(keys);
681 }
682
683 /*
684 * Process SSH2_MSG_NEWKEYS message. If we are using the engine we must have
685 * both SSH2_MSG_NEWKEYS processed before we can finish the engine, fork, and
686 * reinitialize the crypto contexts. We can't fork before processing the 2nd
687 * message otherwise we couldn't encrypt/decrypt that message at all - note that
688 * parent's PKCS#11 sessions are useless after the fork and we must process
689 * both SSH2_MSG_NEWKEYS messages using the old keys.
690 */
691 void
692 process_newkeys(int mode)
693 {
694 /* this function is for the client only */
695 if (packet_is_server() != 0)
696 return;
697
698 if (will_daemonize == FIRST_NEWKEYS_PROCESSED) {
699 debug3("both SSH2_MSG_NEWKEYS processed, will daemonize now");
700 cipher_cleanup(&send_context);
701 cipher_cleanup(&receive_context);
702 pkcs11_engine_finish(e);
703 if (daemon(1, 1) < 0) {
704 fatal("daemon() failed: %.200s",
705 strerror(errno));
706 }
707 e = pkcs11_engine_load(e != NULL ? 1 : 0);
708
709 set_newkeys(MODE_OUT);
710 set_newkeys(MODE_IN);
711 will_daemonize = SECOND_NEWKEYS_PROCESSED;
712 packet_send2();
713 } else {
714 if (will_daemonize == DAEMONIZING_REQUESTED)
715 will_daemonize = FIRST_NEWKEYS_PROCESSED;
716 else
717 set_newkeys(mode);
718 }
719 }
720
721 /*
722 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
723 */
724 static void
725 packet_send2_wrapped(void)
726 {
727 u_char type, *cp, *macbuf = NULL;
728 u_char padlen, pad;
729 u_int packet_length = 0;
730 u_int i, len;
731 u_int32_t rnd = 0;
732 Enc *enc = NULL;
733 Mac *mac = NULL;
734 Comp *comp = NULL;
735 int block_size;
736
737 if (newkeys[MODE_OUT] != NULL) {
738 enc = &newkeys[MODE_OUT]->enc;
739 mac = &newkeys[MODE_OUT]->mac;
740 comp = &newkeys[MODE_OUT]->comp;
741 }
742 block_size = enc ? enc->block_size : 8;
743
744 cp = buffer_ptr(&outgoing_packet);
745 type = cp[5];
746
747 #ifdef PACKET_DEBUG
748 debug("plain output packet to be processed (%d bytes):\n",
749 buffer_len(&outgoing_packet));
750 buffer_dump(&outgoing_packet);
751 #endif
752
753 if (comp && comp->enabled) {
754 len = buffer_len(&outgoing_packet);
755 /* skip header, compress only payload */
756 buffer_consume(&outgoing_packet, 5);
757 buffer_clear(&compression_buffer);
758 buffer_compress(&outgoing_packet, &compression_buffer);
759 buffer_clear(&outgoing_packet);
760 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
761 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
762 buffer_len(&compression_buffer));
763 DBG(debug("compression: raw %d compressed %d", len,
764 buffer_len(&outgoing_packet)));
765 }
766
767 /* sizeof (packet_len + pad_len + payload) */
768 len = buffer_len(&outgoing_packet);
769
770 /*
771 * calc size of padding, alloc space, get random data,
772 * minimum padding is 4 bytes
773 */
774 padlen = block_size - (len % block_size);
775 if (padlen < 4)
776 padlen += block_size;
777 if (extra_pad) {
778 /* will wrap if extra_pad+padlen > 255 */
779 extra_pad = roundup(extra_pad, block_size);
780 pad = extra_pad - ((len + padlen) % extra_pad);
781 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
782 pad, len, padlen, extra_pad);
783 padlen += pad;
784 extra_pad = 0;
785 }
786 cp = buffer_append_space(&outgoing_packet, padlen);
787 if (enc && !send_context.plaintext) {
788 /* random padding */
789 for (i = 0; i < padlen; i++) {
790 if (i % 4 == 0)
791 rnd = arc4random();
792 cp[i] = rnd & 0xff;
793 rnd >>= 8;
794 }
795 } else {
796 /* clear padding */
797 memset(cp, 0, padlen);
798 }
799 /* packet_length includes payload, padding and padding length field */
800 packet_length = buffer_len(&outgoing_packet) - 4;
801 cp = buffer_ptr(&outgoing_packet);
802 PUT_32BIT(cp, packet_length);
803 cp[4] = padlen;
804 DBG(debug("will send %d bytes (includes padlen %d)",
805 packet_length + 4, padlen));
806
807 /* compute MAC over seqnr and packet(length fields, payload, padding) */
808 if (mac && mac->enabled) {
809 macbuf = mac_compute(mac, p_send.seqnr,
810 buffer_ptr(&outgoing_packet),
811 buffer_len(&outgoing_packet));
812 DBG(debug("done calc MAC out #%d", p_send.seqnr));
813 }
814 /* encrypt packet and append to output buffer. */
815 cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
816 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
817 buffer_len(&outgoing_packet));
818 /* append unencrypted MAC */
819 if (mac && mac->enabled)
820 buffer_append(&output, (char *)macbuf, mac->mac_len);
821 #ifdef PACKET_DEBUG
822 debug("encrypted output queue now contains (%d bytes):\n",
823 buffer_len(&output));
824 buffer_dump(&output);
825 #endif
826 /* increment sequence number for outgoing packets */
827 if (++p_send.seqnr == 0)
828 log("outgoing seqnr wraps around");
829
830 /*
831 * RFC 4344: 3.1. First Rekeying Recommendation
832 *
833 * "Because of possible information leakage through the MAC tag after a
834 * key exchange, .... an SSH implementation SHOULD NOT send more than
835 * 2**32 packets before rekeying again."
836 *
837 * The code below is a hard check so that we are sure we don't go across
838 * the suggestion. However, since the largest cipher block size we have
839 * (AES) is 16 bytes we can't reach 2^32 SSH packets encrypted with the
840 * same key while performing periodic rekeying.
841 */
842 if (++p_send.packets == 0)
843 if (!(datafellows & SSH_BUG_NOREKEY))
844 fatal("too many packets encrypted with same key");
845 p_send.blocks += (packet_length + 4) / block_size;
846 buffer_clear(&outgoing_packet);
847
848 if (type == SSH2_MSG_NEWKEYS) {
849 /*
850 * set_newkeys(MODE_OUT) in the client. Note that in the
851 * unprivileged child, set_newkeys() for MODE_OUT are set after
852 * SSH2_MSG_NEWKEYS is read from the monitor and forwarded to
853 * the client side.
854 */
855 process_newkeys(MODE_OUT);
856 }
857 }
858
859 /*
860 * Packets we deal with here are plain until we encrypt them in
861 * packet_send2_wrapped().
862 *
863 * As already mentioned in a comment at process_newkeys() function we must not
864 * fork() until both SSH2_MSG_NEWKEYS packets were processed. Until this is done
865 * we must queue all packets so that they can be encrypted with the new keys and
866 * then sent to the other side. However, what can happen here is that we get
867 * SSH2_MSG_NEWKEYS after we sent it. In that situation we must call
868 * packet_send2() anyway to empty the queue, and set the rekey flag to the
869 * finished state. If we didn't do that we would just hang and enqueue data.
870 */
871 static void
872 packet_send2(void)
873 {
874 static int rekeying = 0;
875 struct packet *p;
876 u_char type, *cp;
877
878 if (will_daemonize != SECOND_NEWKEYS_PROCESSED) {
879 cp = buffer_ptr(&outgoing_packet);
880 type = cp[5];
881
882 /* during rekeying we can only send key exchange messages */
883 if (rekeying) {
884 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
885 (type <= SSH2_MSG_TRANSPORT_MAX))) {
886 debug("enqueue a plain packet because rekex in "
887 "progress [type %u]", type);
888 p = xmalloc(sizeof(*p));
889 p->type = type;
890 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
891 buffer_init(&outgoing_packet);
892 TAILQ_INSERT_TAIL(&outgoing, p, next);
893 return;
894 }
895 }
896
897 /* rekeying starts with sending KEXINIT */
898 if (type == SSH2_MSG_KEXINIT)
899 rekeying = 1;
900
901 packet_send2_wrapped();
902 }
903
904 /* after rekex is done we can process the queue of plain packets */
905 if (will_daemonize == SECOND_NEWKEYS_PROCESSED ||
906 (will_daemonize == NOT_DAEMONIZING && type == SSH2_MSG_NEWKEYS)) {
907 rekeying = 0;
908 will_daemonize = NOT_DAEMONIZING;
909 while ((p = TAILQ_FIRST(&outgoing)) != NULL) {
910 type = p->type;
911 debug("dequeuing a plain packet since rekex is over "
912 "[type %u]", type);
913 buffer_free(&outgoing_packet);
914 memcpy(&outgoing_packet, &p->payload, sizeof(Buffer));
915 TAILQ_REMOVE(&outgoing, p, next);
916 xfree(p);
917 packet_send2_wrapped();
918 }
919 }
920 }
921
922 void
923 packet_send(void)
924 {
925 if (compat20)
926 packet_send2();
927 else
928 packet_send1();
929 DBG(debug("packet_send done"));
930 }
931
932 /*
933 * Waits until a packet has been received, and returns its type. Note that
934 * no other data is processed until this returns, so this function should not
935 * be used during the interactive session.
936 *
937 * The function is also used in the monitor to read the authentication context
938 * in aps_read_auth_context() via packet_read_seqnr(), before the monitor enters
939 * aps_monitor_loop() and starts using the process_input() function.
940 */
941 int
942 packet_read_seqnr(u_int32_t *seqnr_p)
943 {
944 int type, len;
945 fd_set *setp;
946 char buf[8192];
947 DBG(debug("packet_read()"));
948
949 setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) *
950 sizeof(fd_mask));
951
952 /* Since we are blocking, ensure that all written packets have been sent. */
953 packet_write_wait();
954
955 /* Stay in the loop until we have received a complete packet. */
956 for (;;) {
957 /* Try to read a packet from the buffer. */
958 type = packet_read_poll_seqnr(seqnr_p);
959 if (!compat20 && (
960 type == SSH_SMSG_SUCCESS
961 || type == SSH_SMSG_FAILURE
962 || type == SSH_CMSG_EOF
963 || type == SSH_CMSG_EXIT_CONFIRMATION))
964 packet_check_eom();
965 /* If we got a packet, return it. */
966 if (type != SSH_MSG_NONE) {
967 xfree(setp);
968 return type;
969 }
970 /*
971 * Otherwise, wait for some data to arrive, add it to the
972 * buffer, and try again.
973 */
974 memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
975 sizeof(fd_mask));
976 FD_SET(connection_in, setp);
977
978 /* Wait for some data to arrive. */
979 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 &&
980 (errno == EAGAIN || errno == EINTR))
981 ;
982
983 /* Read data from the socket. */
984 len = read(connection_in, buf, sizeof(buf));
985 if (len == 0) {
986 if (packet_connection_is_on_socket())
987 log("Connection closed by %.200s",
988 get_remote_ipaddr());
989 else
990 debug("child closed the communication pipe "
991 "before user auth was finished");
992 fatal_cleanup();
993 }
994 if (len < 0) {
995 if (packet_connection_is_on_socket())
996 fatal("Read from socket failed: %.100s",
997 strerror(errno));
998 else
999 fatal("Read from communication pipe failed: "
1000 "%.100s", strerror(errno));
1001 }
1002 /* Append it to the buffer. */
1003 packet_process_incoming(buf, len);
1004 }
1005 /* NOTREACHED */
1006 }
1007
1008 int
1009 packet_read(void)
1010 {
1011 return packet_read_seqnr(NULL);
1012 }
1013
1014 /*
1015 * Waits until a packet has been received, verifies that its type matches
1016 * that given, and gives a fatal error and exits if there is a mismatch.
1017 */
1018
1019 void
1020 packet_read_expect(int expected_type)
1021 {
1022 int type;
1023
1024 type = packet_read();
1025 if (type != expected_type)
1026 packet_disconnect("Protocol error: expected packet type %d, got %d",
1027 expected_type, type);
1028 }
1029
1030 /* Checks if a full packet is available in the data received so far via
1031 * packet_process_incoming. If so, reads the packet; otherwise returns
1032 * SSH_MSG_NONE. This does not wait for data from the connection.
1033 *
1034 * SSH_MSG_DISCONNECT is handled specially here. Also,
1035 * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1036 * to higher levels.
1037 */
1038
1039 static int
1040 packet_read_poll1(void)
1041 {
1042 u_int len, padded_len;
1043 u_char *cp, type;
1044 u_int checksum, stored_checksum;
1045
1046 /* Check if input size is less than minimum packet size. */
1047 if (buffer_len(&input) < 4 + 8)
1048 return SSH_MSG_NONE;
1049 /* Get length of incoming packet. */
1050 cp = buffer_ptr(&input);
1051 len = GET_32BIT(cp);
1052 if (len < 1 + 2 + 2 || len > 256 * 1024)
1053 packet_disconnect("Bad packet length %d.", len);
1054 padded_len = (len + 8) & ~7;
1055
1056 /* Check if the packet has been entirely received. */
1057 if (buffer_len(&input) < 4 + padded_len)
1058 return SSH_MSG_NONE;
1059
1060 /* The entire packet is in buffer. */
1061
1062 /* Consume packet length. */
1063 buffer_consume(&input, 4);
1064
1065 /*
1066 * Cryptographic attack detector for ssh
1067 * (C)1998 CORE-SDI, Buenos Aires Argentina
1068 * Ariel Futoransky(futo@core-sdi.com)
1069 */
1070 if (!receive_context.plaintext) {
1071 switch (detect_attack(buffer_ptr(&input), padded_len, NULL)) {
1072 case DEATTACK_DETECTED:
1073 packet_disconnect("crc32 compensation attack: "
1074 "network attack detected");
1075 break;
1076 case DEATTACK_DOS_DETECTED:
1077 packet_disconnect("deattack denial of "
1078 "service detected");
1079 break;
1080 }
1081 }
1082
1083 /* Decrypt data to incoming_packet. */
1084 buffer_clear(&incoming_packet);
1085 cp = buffer_append_space(&incoming_packet, padded_len);
1086 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
1087
1088 buffer_consume(&input, padded_len);
1089
1090 #ifdef PACKET_DEBUG
1091 debug("read_poll plain/full:\n");
1092 buffer_dump(&incoming_packet);
1093 #endif
1094
1095 /* Compute packet checksum. */
1096 checksum = ssh_crc32(buffer_ptr(&incoming_packet),
1097 buffer_len(&incoming_packet) - 4);
1098
1099 /* Skip padding. */
1100 buffer_consume(&incoming_packet, 8 - len % 8);
1101
1102 /* Test check bytes. */
1103 if (len != buffer_len(&incoming_packet))
1104 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1105 len, buffer_len(&incoming_packet));
1106
1107 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
1108 stored_checksum = GET_32BIT(cp);
1109 if (checksum != stored_checksum)
1110 packet_disconnect("Corrupted check bytes on input.");
1111 buffer_consume_end(&incoming_packet, 4);
1112
1113 if (packet_compression) {
1114 buffer_clear(&compression_buffer);
1115 buffer_uncompress(&incoming_packet, &compression_buffer);
1116 buffer_clear(&incoming_packet);
1117 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1118 buffer_len(&compression_buffer));
1119 }
1120 type = buffer_get_char(&incoming_packet);
1121 return type;
1122 }
1123
1124 static int
1125 packet_read_poll2(u_int32_t *seqnr_p)
1126 {
1127 static u_int packet_length = 0;
1128 u_int padlen, need;
1129 u_char *macbuf, *cp, type;
1130 int maclen, block_size;
1131 Enc *enc = NULL;
1132 Mac *mac = NULL;
1133 Comp *comp = NULL;
1134
1135 if (newkeys[MODE_IN] != NULL) {
1136 enc = &newkeys[MODE_IN]->enc;
1137 mac = &newkeys[MODE_IN]->mac;
1138 comp = &newkeys[MODE_IN]->comp;
1139 }
1140 maclen = mac && mac->enabled ? mac->mac_len : 0;
1141 block_size = enc ? enc->block_size : 8;
1142
1143 if (packet_length == 0) {
1144 /*
1145 * check if input size is less than the cipher block size,
1146 * decrypt first block and extract length of incoming packet
1147 */
1148 if (buffer_len(&input) < block_size)
1149 return SSH_MSG_NONE;
1150 #ifdef PACKET_DEBUG
1151 debug("encrypted data we have in read queue (%d bytes):\n",
1152 buffer_len(&input));
1153 buffer_dump(&input);
1154 #endif
1155 buffer_clear(&incoming_packet);
1156 cp = buffer_append_space(&incoming_packet, block_size);
1157 cipher_crypt(&receive_context, cp, buffer_ptr(&input),
1158 block_size);
1159 cp = buffer_ptr(&incoming_packet);
1160 packet_length = GET_32BIT(cp);
1161 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
1162 packet_disconnect("Bad packet length.");
1163 }
1164 DBG(debug("input: packet len %u", packet_length + 4));
1165 buffer_consume(&input, block_size);
1166 }
1167 /* we have a partial packet of block_size bytes */
1168 need = 4 + packet_length - block_size;
1169 DBG(debug("partial packet %d, still need %d, maclen %d", block_size,
1170 need, maclen));
1171 if (need % block_size != 0)
1172 packet_disconnect("Bad packet length.");
1173 /*
1174 * check if the entire packet has been received and
1175 * decrypt into incoming_packet
1176 */
1177 if (buffer_len(&input) < need + maclen)
1178 return SSH_MSG_NONE;
1179 #ifdef PACKET_DEBUG
1180 debug("in read_poll, the encrypted input queue now contains "
1181 "(%d bytes):\n", buffer_len(&input));
1182 buffer_dump(&input);
1183 #endif
1184 cp = buffer_append_space(&incoming_packet, need);
1185 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
1186 buffer_consume(&input, need);
1187 /*
1188 * compute MAC over seqnr and packet,
1189 * increment sequence number for incoming packet
1190 */
1191 if (mac && mac->enabled) {
1192 macbuf = mac_compute(mac, p_read.seqnr,
1193 buffer_ptr(&incoming_packet),
1194 buffer_len(&incoming_packet));
1195 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
1196 packet_disconnect("Corrupted MAC on input.");
1197 DBG(debug("MAC #%d ok", p_read.seqnr));
1198 buffer_consume(&input, mac->mac_len);
1199 }
1200 if (seqnr_p != NULL)
1201 *seqnr_p = p_read.seqnr;
1202 if (++p_read.seqnr == 0)
1203 log("incoming seqnr wraps around");
1204
1205 /* see above for the comment on "First Rekeying Recommendation" */
1206 if (++p_read.packets == 0)
1207 if (!(datafellows & SSH_BUG_NOREKEY))
1208 fatal("too many packets with same key");
1209 p_read.blocks += (packet_length + 4) / block_size;
1210
1211 /* get padlen */
1212 cp = buffer_ptr(&incoming_packet);
1213 padlen = cp[4];
1214 DBG(debug("input: padlen %d", padlen));
1215 if (padlen < 4)
1216 packet_disconnect("Corrupted padlen %d on input.", padlen);
1217
1218 /* skip packet size + padlen, discard padding */
1219 buffer_consume(&incoming_packet, 4 + 1);
1220 buffer_consume_end(&incoming_packet, padlen);
1221
1222 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
1223 if (comp && comp->enabled) {
1224 buffer_clear(&compression_buffer);
1225 buffer_uncompress(&incoming_packet, &compression_buffer);
1226 buffer_clear(&incoming_packet);
1227 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1228 buffer_len(&compression_buffer));
1229 DBG(debug("input: len after de-compress %d",
1230 buffer_len(&incoming_packet)));
1231 }
1232 /*
1233 * get packet type, implies consume.
1234 * return length of payload (without type field)
1235 */
1236 type = buffer_get_char(&incoming_packet);
1237 if (type == SSH2_MSG_NEWKEYS) {
1238 /*
1239 * set_newkeys(MODE_IN) in the client because it doesn't have a
1240 * dispatch function for SSH2_MSG_NEWKEYS in contrast to the
1241 * server processes. Note that in the unprivileged child,
1242 * set_newkeys() for MODE_IN are set in dispatch function
1243 * altprivsep_rekey() after SSH2_MSG_NEWKEYS packet is received
1244 * from the client.
1245 */
1246 process_newkeys(MODE_IN);
1247 }
1248
1249 #ifdef PACKET_DEBUG
1250 debug("decrypted input packet [type %d]:\n", type);
1251 buffer_dump(&incoming_packet);
1252 #endif
1253 /* reset for next packet */
1254 packet_length = 0;
1255 return type;
1256 }
1257
1258 /*
1259 * This tries to read a packet from the buffer of received data. Note that it
1260 * doesn't read() anything from the network socket.
1261 */
1262 int
1263 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1264 {
1265 u_int reason, seqnr;
1266 u_char type;
1267 char *msg;
1268
1269 for (;;) {
1270 if (compat20) {
1271 type = packet_read_poll2(seqnr_p);
1272 DBG(debug("received packet type %d", type));
1273 switch (type) {
1274 case SSH2_MSG_IGNORE:
1275 break;
1276 case SSH2_MSG_DEBUG:
1277 packet_get_char();
1278 msg = packet_get_utf8_string(NULL);
1279 msg = g11n_filter_string(msg);
1280 debug("Remote: %.900s", msg);
1281 xfree(msg);
1282 msg = packet_get_string(NULL);
1283 xfree(msg);
1284 break;
1285 case SSH2_MSG_DISCONNECT:
1286 reason = packet_get_int();
1287 msg = packet_get_utf8_string(NULL);
1288 msg = g11n_filter_string(msg);
1289 log("Received disconnect from %s: %u: %.400s",
1290 get_remote_ipaddr(), reason, msg);
1291 xfree(msg);
1292 fatal_cleanup();
1293 break;
1294 case SSH2_MSG_UNIMPLEMENTED:
1295 seqnr = packet_get_int();
1296 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1297 seqnr);
1298 break;
1299 default:
1300 return type;
1301 break;
1302 }
1303 } else {
1304 type = packet_read_poll1();
1305 DBG(debug("received packet type %d", type));
1306 switch (type) {
1307 case SSH_MSG_IGNORE:
1308 break;
1309 case SSH_MSG_DEBUG:
1310 msg = packet_get_string(NULL);
1311 debug("Remote: %.900s", msg);
1312 xfree(msg);
1313 break;
1314 case SSH_MSG_DISCONNECT:
1315 msg = packet_get_string(NULL);
1316 log("Received disconnect from %s: %.400s",
1317 get_remote_ipaddr(), msg);
1318 fatal_cleanup();
1319 xfree(msg);
1320 break;
1321 default:
1322 return type;
1323 break;
1324 }
1325 }
1326 }
1327 }
1328
1329 int
1330 packet_read_poll(void)
1331 {
1332 return packet_read_poll_seqnr(NULL);
1333 }
1334
1335 /*
1336 * Buffers the given amount of input characters. This is intended to be used
1337 * together with packet_read_poll.
1338 */
1339
1340 void
1341 packet_process_incoming(const char *buf, u_int len)
1342 {
1343 buffer_append(&input, buf, len);
1344 }
1345
1346 /* Returns a character from the packet. */
1347
1348 u_int
1349 packet_get_char(void)
1350 {
1351 char ch;
1352
1353 buffer_get(&incoming_packet, &ch, 1);
1354 return (u_char) ch;
1355 }
1356
1357 /* Returns an integer from the packet data. */
1358
1359 u_int
1360 packet_get_int(void)
1361 {
1362 return buffer_get_int(&incoming_packet);
1363 }
1364
1365 /*
1366 * Returns an arbitrary precision integer from the packet data. The integer
1367 * must have been initialized before this call.
1368 */
1369
1370 void
1371 packet_get_bignum(BIGNUM * value)
1372 {
1373 buffer_get_bignum(&incoming_packet, value);
1374 }
1375
1376 void
1377 packet_get_bignum2(BIGNUM * value)
1378 {
1379 buffer_get_bignum2(&incoming_packet, value);
1380 }
1381
1382 void *
1383 packet_get_raw(u_int *length_ptr)
1384 {
1385 u_int bytes = buffer_len(&incoming_packet);
1386
1387 if (length_ptr != NULL)
1388 *length_ptr = bytes;
1389 return buffer_ptr(&incoming_packet);
1390 }
1391
1392 int
1393 packet_remaining(void)
1394 {
1395 return buffer_len(&incoming_packet);
1396 }
1397
1398 /*
1399 * Returns a string from the packet data. The string is allocated using
1400 * xmalloc; it is the responsibility of the calling program to free it when
1401 * no longer needed. The length_ptr argument may be NULL, or point to an
1402 * integer into which the length of the string is stored.
1403 */
1404
1405 void *
1406 packet_get_string(u_int *length_ptr)
1407 {
1408 return buffer_get_string(&incoming_packet, length_ptr);
1409 }
1410
1411 char *
1412 packet_get_utf8_string(uint_t *length_ptr)
1413 {
1414 if (datafellows & SSH_BUG_STRING_ENCODING)
1415 return (buffer_get_string(&incoming_packet, length_ptr));
1416 else
1417 return (buffer_get_utf8_string(&incoming_packet, length_ptr));
1418 }
1419
1420 /*
1421 * Sends a diagnostic message from the server to the client. This message
1422 * can be sent at any time (but not while constructing another message). The
1423 * message is printed immediately, but only if the client is being executed
1424 * in verbose mode. These messages are primarily intended to ease debugging
1425 * authentication problems. The length of the formatted message must not
1426 * exceed 1024 bytes. This will automatically call packet_write_wait.
1427 */
1428
1429 void
1430 packet_send_debug(const char *fmt,...)
1431 {
1432 char buf[1024];
1433 va_list args;
1434
1435 if (compat20 && (datafellows & SSH_BUG_DEBUG))
1436 return;
1437
1438 va_start(args, fmt);
1439 vsnprintf(buf, sizeof(buf), gettext(fmt), args);
1440 va_end(args);
1441
1442 #ifdef ALTPRIVSEP
1443 /* shouldn't happen */
1444 if (packet_monitor) {
1445 debug("packet_send_debug: %s", buf);
1446 return;
1447 }
1448 #endif /* ALTPRIVSEP */
1449
1450 if (compat20) {
1451 packet_start(SSH2_MSG_DEBUG);
1452 packet_put_char(0); /* bool: always display */
1453 packet_put_utf8_cstring(buf);
1454 packet_put_cstring("");
1455 } else {
1456 packet_start(SSH_MSG_DEBUG);
1457 packet_put_cstring(buf);
1458 }
1459 packet_send();
1460 packet_write_wait();
1461 }
1462
1463 /*
1464 * Logs the error plus constructs and sends a disconnect packet, closes the
1465 * connection, and exits. This function never returns. The error message
1466 * should not contain a newline. The length of the formatted message must
1467 * not exceed 1024 bytes.
1468 */
1469
1470 void
1471 packet_disconnect(const char *fmt,...)
1472 {
1473 char buf[1024];
1474 va_list args;
1475 static int disconnecting = 0;
1476
1477 if (disconnecting) /* Guard against recursive invocations. */
1478 fatal("packet_disconnect called recursively.");
1479 disconnecting = 1;
1480
1481 /*
1482 * Format the message. Note that the caller must make sure the
1483 * message is of limited size.
1484 */
1485 va_start(args, fmt);
1486 vsnprintf(buf, sizeof(buf), fmt, args);
1487 va_end(args);
1488
1489 #ifdef ALTPRIVSEP
1490 /*
1491 * If we packet_disconnect() in the monitor the fatal cleanups will take
1492 * care of the child. See main() in sshd.c. We don't send the packet
1493 * disconnect message here because: a) the child might not be looking
1494 * for it and b) because we don't really know if the child is compat20
1495 * or not as we lost that information when packet_set_monitor() was
1496 * called.
1497 */
1498 if (packet_monitor)
1499 goto close_stuff;
1500 #endif /* ALTPRIVSEP */
1501
1502 /* Send the disconnect message to the other side, and wait for it to get sent. */
1503 if (compat20) {
1504 packet_start(SSH2_MSG_DISCONNECT);
1505 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1506 packet_put_utf8_cstring(buf);
1507 packet_put_cstring("");
1508 } else {
1509 packet_start(SSH_MSG_DISCONNECT);
1510 packet_put_cstring(buf);
1511 }
1512 packet_send();
1513 packet_write_wait();
1514
1515 #ifdef ALTPRIVSEP
1516 close_stuff:
1517 #endif /* ALTPRIVSEP */
1518 /* Stop listening for connections. */
1519 channel_close_all();
1520
1521 /* Close the connection. */
1522 packet_close();
1523
1524 /* Display the error locally and exit. */
1525 log("Disconnecting: %.100s", buf);
1526 fatal_cleanup();
1527 }
1528
1529 /* Checks if there is any buffered output, and tries to write some of the output. */
1530
1531 void
1532 packet_write_poll(void)
1533 {
1534 int len = buffer_len(&output);
1535
1536 if (len > 0) {
1537 len = write(connection_out, buffer_ptr(&output), len);
1538 if (len <= 0) {
1539 if (errno == EAGAIN)
1540 return;
1541 else
1542 fatal("Write failed: %.100s", strerror(errno));
1543 }
1544 #ifdef PACKET_DEBUG
1545 debug("in packet_write_poll, %d bytes just sent to the "
1546 "remote side", len);
1547 #endif
1548 buffer_consume(&output, len);
1549 }
1550 }
1551
1552 /*
1553 * Calls packet_write_poll repeatedly until all pending output data has been
1554 * written.
1555 */
1556
1557 void
1558 packet_write_wait(void)
1559 {
1560 fd_set *setp;
1561
1562 setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) *
1563 sizeof(fd_mask));
1564 packet_write_poll();
1565 while (packet_have_data_to_write()) {
1566 memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1567 sizeof(fd_mask));
1568 FD_SET(connection_out, setp);
1569 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 &&
1570 (errno == EAGAIN || errno == EINTR))
1571 ;
1572 packet_write_poll();
1573 }
1574 xfree(setp);
1575 }
1576
1577 /* Returns true if there is buffered data to write to the connection. */
1578
1579 int
1580 packet_have_data_to_write(void)
1581 {
1582 return buffer_len(&output) != 0;
1583 }
1584
1585 /* Returns true if there is not too much data to write to the connection. */
1586
1587 int
1588 packet_not_very_much_data_to_write(void)
1589 {
1590 if (interactive_mode)
1591 return buffer_len(&output) < 16384;
1592 else
1593 return buffer_len(&output) < 128 * 1024;
1594 }
1595
1596 /* Informs that the current session is interactive. Sets IP flags for that. */
1597
1598 void
1599 packet_set_interactive(int interactive)
1600 {
1601 static int called = 0;
1602 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1603 int lowdelay = IPTOS_LOWDELAY;
1604 int throughput = IPTOS_THROUGHPUT;
1605 #endif
1606
1607 if (called)
1608 return;
1609 called = 1;
1610
1611 /* Record that we are in interactive mode. */
1612 interactive_mode = interactive;
1613
1614 /* Only set socket options if using a socket. */
1615 if (!packet_connection_is_on_socket())
1616 return;
1617 /*
1618 * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only
1619 */
1620 if (interactive) {
1621 /*
1622 * Set IP options for an interactive connection. Use
1623 * IPTOS_LOWDELAY and TCP_NODELAY.
1624 */
1625 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1626 if (packet_connection_is_ipv4()) {
1627 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS,
1628 &lowdelay, sizeof(lowdelay)) < 0)
1629 error("setsockopt IPTOS_LOWDELAY: %.100s",
1630 strerror(errno));
1631 }
1632 #endif
1633 set_nodelay(connection_in);
1634 }
1635 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1636 else if (packet_connection_is_ipv4()) {
1637 /*
1638 * Set IP options for a non-interactive connection. Use
1639 * IPTOS_THROUGHPUT.
1640 */
1641 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &throughput,
1642 sizeof(throughput)) < 0)
1643 error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno));
1644 }
1645 #endif
1646 }
1647
1648 /* Returns true if the current connection is interactive. */
1649
1650 int
1651 packet_is_interactive(void)
1652 {
1653 return interactive_mode;
1654 }
1655
1656 int
1657 packet_set_maxsize(int s)
1658 {
1659 static int called = 0;
1660
1661 if (called) {
1662 log("packet_set_maxsize: called twice: old %d new %d",
1663 max_packet_size, s);
1664 return -1;
1665 }
1666 if (s < 4 * 1024 || s > 1024 * 1024) {
1667 log("packet_set_maxsize: bad size %d", s);
1668 return -1;
1669 }
1670 called = 1;
1671 debug("packet_set_maxsize: setting to %d", s);
1672 max_packet_size = s;
1673 return s;
1674 }
1675
1676 /* roundup current message to pad bytes */
1677 void
1678 packet_add_padding(u_char pad)
1679 {
1680 extra_pad = pad;
1681 }
1682
1683 /*
1684 * 9.2. Ignored Data Message
1685 *
1686 * byte SSH_MSG_IGNORE
1687 * string data
1688 *
1689 * All implementations MUST understand (and ignore) this message at any
1690 * time (after receiving the protocol version). No implementation is
1691 * required to send them. This message can be used as an additional
1692 * protection measure against advanced traffic analysis techniques.
1693 */
1694 void
1695 packet_send_ignore(int nbytes)
1696 {
1697 u_int32_t rnd = 0;
1698 int i;
1699
1700 #ifdef ALTPRIVSEP
1701 /* shouldn't happen -- see packet_set_monitor() */
1702 if (packet_monitor)
1703 return;
1704 #endif /* ALTPRIVSEP */
1705
1706 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1707 packet_put_int(nbytes);
1708 for (i = 0; i < nbytes; i++) {
1709 if (i % 4 == 0)
1710 rnd = arc4random();
1711 packet_put_char((u_char)rnd & 0xff);
1712 rnd >>= 8;
1713 }
1714 }
1715
1716 #define MAX_PACKETS (1U<<31)
1717 int
1718 packet_need_rekeying(void)
1719 {
1720 if (datafellows & SSH_BUG_NOREKEY)
1721 return 0;
1722 return
1723 (p_send.packets > MAX_PACKETS) ||
1724 (p_read.packets > MAX_PACKETS) ||
1725 (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
1726 (max_blocks_in && (p_read.blocks > max_blocks_in));
1727 }
1728
1729 void
1730 packet_set_rekey_limit(u_int32_t bytes)
1731 {
1732 rekey_limit = bytes;
1733 }
1734
1735 #ifdef ALTPRIVSEP
1736 void
1737 packet_set_server(void)
1738 {
1739 packet_server = 1;
1740 }
1741
1742 int
1743 packet_is_server(void)
1744 {
1745 return (packet_server);
1746 }
1747
1748 void
1749 packet_set_monitor(int pipe)
1750 {
1751 int dup_fd;
1752
1753 packet_server = 1;
1754 packet_monitor = 1;
1755
1756 /*
1757 * Awful hack follows.
1758 *
1759 * For SSHv1 the monitor does not process any SSHv1 packets, only
1760 * ALTPRIVSEP packets. We take advantage of that here to keep changes
1761 * to packet.c to a minimum by using the SSHv2 binary packet protocol,
1762 * with cipher "none," mac "none" and compression alg "none," as the
1763 * basis for the monitor protocol. And so to force packet.c to treat
1764 * packets as SSHv2 we force compat20 == 1 here.
1765 *
1766 * For completeness and to help future developers catch this we also
1767 * force compat20 == 1 in the monitor loop, in serverloop.c.
1768 */
1769 compat20 = 1;
1770
1771 /*
1772 * NOTE: Assumptions below!
1773 *
1774 * - lots of packet.c code assumes that (connection_in ==
1775 * connection_out) -> connection is socket
1776 *
1777 * - packet_close() does not shutdown() the connection fildes
1778 * if connection_in != connection_out
1779 *
1780 * - other code assumes the connection is a socket if
1781 * connection_in == connection_out
1782 */
1783
1784 if ((dup_fd = dup(pipe)) < 0)
1785 fatal("Monitor failed to start: %s", strerror(errno));
1786
1787 /*
1788 * make sure that the monitor's child's socket is not shutdown(3SOCKET)
1789 * when we packet_close(). Setting connection_out to -1 will take care
1790 * of that.
1791 */
1792 if (packet_connection_is_on_socket())
1793 connection_out = -1;
1794
1795 /*
1796 * Now clean up the state related to the server socket. As a side
1797 * effect, we also clean up existing cipher contexts that were
1798 * initialized with 'none' cipher in packet_set_connection(). That
1799 * function was called in the child server process shortly after the
1800 * master SSH process forked. However, all of that is reinialized again
1801 * by another packet_set_connection() call right below.
1802 */
1803 packet_close();
1804
1805 /*
1806 * Now make the monitor pipe look like the ssh connection which means
1807 * that connection_in and connection_out will be set to the
1808 * communication pipe descriptors.
1809 */
1810 packet_set_connection(pipe, dup_fd);
1811 }
1812
1813 /*
1814 * We temporarily need to set connection_in and connection_out descriptors so
1815 * that we can make use of existing code that gets the IP address and hostname
1816 * of the peer to write a login/logout record. It's not nice but we would have
1817 * to change more code when implementing the PKCS#11 engine support.
1818 */
1819 void
1820 packet_set_fds(int fd, int restore)
1821 {
1822 static int stored_fd;
1823
1824 if (stored_fd == 0 && restore == 0) {
1825 debug3("packet_set_fds: saving %d, installing %d",
1826 connection_in, fd);
1827 stored_fd = connection_in;
1828 /* we don't have a socket in inetd mode */
1829 if (fd != -1)
1830 connection_in = connection_out = fd;
1831 return;
1832 }
1833
1834 if (restore == 1) {
1835 debug3("restoring %d to connection_in/out", stored_fd);
1836 connection_in = connection_out = stored_fd;
1837 }
1838 }
1839
1840 int
1841 packet_is_monitor(void)
1842 {
1843 return (packet_monitor);
1844 }
1845 #endif /* ALTPRIVSEP */