1 /* $OpenBSD: packet.c,v 1.166 2009/06/27 09:29:06 andreas Exp $ */
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * This file contains code implementing the packet protocol and communication
7 * with the other side. This same code is used both on client and server side.
8 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
14 *
15 *
16 * SSH2 packet format added by Markus Friedl.
17 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
18 *
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
21 * are met:
22 * 1. Redistributions of source code must retain the above copyright
23 * notice, this list of conditions and the following disclaimer.
24 * 2. Redistributions in binary form must reproduce the above copyright
25 * notice, this list of conditions and the following disclaimer in the
26 * documentation and/or other materials provided with the distribution.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38 */
39
40 #include <sys/param.h>
41 #include <sys/queue.h>
42 #include <sys/socket.h>
43 #include <sys/time.h>
44
45 #include <netinet/in_systm.h>
46 #include <netinet/in.h>
47 #include <netinet/ip.h>
48
49 #include <errno.h>
50 #include <stdarg.h>
51 #include <stdio.h>
52 #include <stdlib.h>
53 #include <string.h>
54 #include <unistd.h>
55 #include <signal.h>
56
57 #include "xmalloc.h"
58 #include "buffer.h"
59 #include "packet.h"
60 #include "crc32.h"
61 #include "compress.h"
62 #include "deattack.h"
63 #include "channels.h"
64 #include "compat.h"
65 #include "ssh1.h"
66 #include "ssh2.h"
67 #include "cipher.h"
68 #include "key.h"
69 #include "kex.h"
70 #include "mac.h"
71 #include "log.h"
72 #include "canohost.h"
73 #include "misc.h"
74 #include "ssh.h"
75 #include "roaming.h"
76
77 __RCSID("$MirOS: src/usr.bin/ssh/packet.c,v 1.17 2010/09/21 21:24:37 tg Exp $");
78
79 const char NULs[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
80
81 #ifdef PACKET_DEBUG
82 #define DBG(x) x
83 #else
84 #define DBG(x)
85 #endif
86
87 #define PACKET_MAX_SIZE (256 * 1024)
88
89 struct packet_state {
90 u_int32_t seqnr;
91 u_int32_t packets;
92 u_int64_t blocks;
93 u_int64_t bytes;
94 };
95
96 struct packet {
97 TAILQ_ENTRY(packet) next;
98 u_char type;
99 Buffer payload;
100 };
101
102 struct session_state {
103 /*
104 * This variable contains the file descriptors used for
105 * communicating with the other side. connection_in is used for
106 * reading; connection_out for writing. These can be the same
107 * descriptor, in which case it is assumed to be a socket.
108 */
109 int connection_in;
110 int connection_out;
111
112 /* Protocol flags for the remote side. */
113 u_int remote_protocol_flags;
114
115 /* Encryption context for receiving data. Only used for decryption. */
116 CipherContext receive_context;
117
118 /* Encryption context for sending data. Only used for encryption. */
119 CipherContext send_context;
120
121 /* Buffer for raw input data from the socket. */
122 Buffer input;
123
124 /* Buffer for raw output data going to the socket. */
125 Buffer output;
126
127 /* Buffer for the partial outgoing packet being constructed. */
128 Buffer outgoing_packet;
129
130 /* Buffer for the incoming packet currently being processed. */
131 Buffer incoming_packet;
132
133 /* Scratch buffer for packet compression/decompression. */
134 Buffer compression_buffer;
135 int compression_buffer_ready;
136
137 /*
138 * Flag indicating whether packet compression/decompression is
139 * enabled.
140 */
141 int packet_compression;
142
143 /* default maximum packet size */
144 u_int max_packet_size;
145
146 /* Flag indicating whether this module has been initialized. */
147 int initialized;
148
149 /* Set to true if the connection is interactive. */
150 int interactive_mode;
151
152 /* Set to true if we are the server side. */
153 int server_side;
154
155 /* Set to true if we are authenticated. */
156 int after_authentication;
157
158 int keep_alive_timeouts;
159
160 /* The maximum time that we will wait to send or receive a packet */
161 int packet_timeout_ms;
162
163 /* Session key information for Encryption and MAC */
164 Newkeys *newkeys[MODE_MAX];
165 struct packet_state p_read, p_send;
166
167 u_int64_t max_blocks_in, max_blocks_out;
168 u_int32_t rekey_limit;
169
170 /* Session key for protocol v1 */
171 u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
172 u_int ssh1_keylen;
173
174 /* roundup current message to extra_pad bytes */
175 u_char extra_pad;
176
177 /* XXX discard incoming data after MAC error */
178 u_int packet_discard;
179 Mac *packet_discard_mac;
180
181 /* Used in packet_read_poll2() */
182 u_int packlen;
183
184 /* Used in packet_send2 */
185 int rekeying;
186
187 /* Used in packet_set_interactive */
188 int set_interactive_called;
189
190 /* Used in packet_set_maxsize */
191 int set_maxsize_called;
192
193 TAILQ_HEAD(, packet) outgoing;
194 };
195
196 static struct session_state *active_state, *backup_state;
197
198 static struct session_state *
alloc_session_state(void)199 alloc_session_state(void)
200 {
201 struct session_state *s = xcalloc(1, sizeof(*s));
202
203 s->connection_in = -1;
204 s->connection_out = -1;
205 s->max_packet_size = 32768;
206 s->packet_timeout_ms = -1;
207 return s;
208 }
209
210 static __dead void packet_stop_discard(void);
211
212 /* MirOS extension */
213 static void packet_consume_ignoremsg(void);
214
215 /*
216 * Sets the descriptors used for communication. Disables encryption until
217 * packet_set_encryption_key is called.
218 */
219 void
packet_set_connection(int fd_in,int fd_out)220 packet_set_connection(int fd_in, int fd_out)
221 {
222 Cipher *none = cipher_by_name("none");
223
224 if (none == NULL)
225 fatal("packet_set_connection: cannot load cipher 'none'");
226 if (active_state == NULL)
227 active_state = alloc_session_state();
228 active_state->connection_in = fd_in;
229 active_state->connection_out = fd_out;
230 cipher_init(&active_state->send_context, none, (const u_char *)&fd_in,
231 sizeof(fd_in), NULL, 0, CIPHER_ENCRYPT);
232 cipher_init(&active_state->receive_context, none, (const u_char *)&fd_out,
233 sizeof(fd_out), NULL, 0, CIPHER_DECRYPT);
234 active_state->newkeys[MODE_IN] = active_state->newkeys[MODE_OUT] = NULL;
235 if (!active_state->initialized) {
236 active_state->initialized = 1;
237 buffer_init(&active_state->input);
238 buffer_init(&active_state->output);
239 buffer_init(&active_state->outgoing_packet);
240 buffer_init(&active_state->incoming_packet);
241 TAILQ_INIT(&active_state->outgoing);
242 active_state->p_send.packets = active_state->p_read.packets = 0;
243 }
244 }
245
246 void
packet_set_timeout(int timeout,int count)247 packet_set_timeout(int timeout, int count)
248 {
249 if (timeout == 0 || count == 0) {
250 active_state->packet_timeout_ms = -1;
251 return;
252 }
253 if ((INT_MAX / 1000) / count < timeout)
254 active_state->packet_timeout_ms = INT_MAX;
255 else
256 active_state->packet_timeout_ms = timeout * count * 1000;
257 }
258
259 static void
packet_stop_discard(void)260 packet_stop_discard(void)
261 {
262 if (active_state->packet_discard_mac) {
263 char buf[1024];
264
265 memset(buf, 'a', sizeof(buf));
266 while (buffer_len(&active_state->incoming_packet) <
267 PACKET_MAX_SIZE)
268 buffer_append(&active_state->incoming_packet, buf,
269 sizeof(buf));
270 (void) mac_compute(active_state->packet_discard_mac,
271 active_state->p_read.seqnr,
272 buffer_ptr(&active_state->incoming_packet),
273 PACKET_MAX_SIZE);
274 }
275 logit("Finished discarding for %.200s", get_remote_ipaddr());
276 cleanup_exit(255);
277 }
278
279 static void
packet_start_discard(Enc * enc,Mac * mac,u_int packet_length,u_int discard)280 packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard)
281 {
282 if (enc == NULL || !cipher_is_cbc(enc->cipher))
283 packet_disconnect("Packet corrupt");
284 if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
285 active_state->packet_discard_mac = mac;
286 if (buffer_len(&active_state->input) >= discard)
287 packet_stop_discard();
288 active_state->packet_discard = discard -
289 buffer_len(&active_state->input);
290 }
291
292 /* Returns 1 if remote host is connected via socket, 0 if not. */
293
294 int
packet_connection_is_on_socket(void)295 packet_connection_is_on_socket(void)
296 {
297 struct sockaddr_storage from, to;
298 socklen_t fromlen, tolen;
299
300 /* filedescriptors in and out are the same, so it's a socket */
301 if (active_state->connection_in == active_state->connection_out)
302 return 1;
303 fromlen = sizeof(from);
304 memset(&from, 0, sizeof(from));
305 if (getpeername(active_state->connection_in, (struct sockaddr *)&from,
306 &fromlen) < 0)
307 return 0;
308 tolen = sizeof(to);
309 memset(&to, 0, sizeof(to));
310 if (getpeername(active_state->connection_out, (struct sockaddr *)&to,
311 &tolen) < 0)
312 return 0;
313 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
314 return 0;
315 if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
316 return 0;
317 return 1;
318 }
319
320 /*
321 * Exports an IV from the CipherContext required to export the key
322 * state back from the unprivileged child to the privileged parent
323 * process.
324 */
325
326 void
packet_get_keyiv(int mode,u_char * iv,u_int len)327 packet_get_keyiv(int mode, u_char *iv, u_int len)
328 {
329 CipherContext *cc;
330
331 if (mode == MODE_OUT)
332 cc = &active_state->send_context;
333 else
334 cc = &active_state->receive_context;
335
336 cipher_get_keyiv(cc, iv, len);
337 }
338
339 int
packet_get_keycontext(int mode,u_char * dat)340 packet_get_keycontext(int mode, u_char *dat)
341 {
342 CipherContext *cc;
343
344 if (mode == MODE_OUT)
345 cc = &active_state->send_context;
346 else
347 cc = &active_state->receive_context;
348
349 return (cipher_get_keycontext(cc, dat));
350 }
351
352 void
packet_set_keycontext(int mode,u_char * dat)353 packet_set_keycontext(int mode, u_char *dat)
354 {
355 CipherContext *cc;
356
357 if (mode == MODE_OUT)
358 cc = &active_state->send_context;
359 else
360 cc = &active_state->receive_context;
361
362 cipher_set_keycontext(cc, dat);
363 }
364
365 int
packet_get_keyiv_len(int mode)366 packet_get_keyiv_len(int mode)
367 {
368 CipherContext *cc;
369
370 if (mode == MODE_OUT)
371 cc = &active_state->send_context;
372 else
373 cc = &active_state->receive_context;
374
375 return (cipher_get_keyiv_len(cc));
376 }
377
378 void
packet_set_iv(int mode,u_char * dat)379 packet_set_iv(int mode, u_char *dat)
380 {
381 CipherContext *cc;
382
383 if (mode == MODE_OUT)
384 cc = &active_state->send_context;
385 else
386 cc = &active_state->receive_context;
387
388 cipher_set_keyiv(cc, dat);
389 }
390
391 int
packet_get_ssh1_cipher(void)392 packet_get_ssh1_cipher(void)
393 {
394 return (cipher_get_number(active_state->receive_context.cipher));
395 }
396
397 void
packet_get_state(int mode,u_int32_t * seqnr,u_int64_t * blocks,u_int32_t * packets,u_int64_t * bytes)398 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets,
399 u_int64_t *bytes)
400 {
401 struct packet_state *state;
402
403 state = (mode == MODE_IN) ?
404 &active_state->p_read : &active_state->p_send;
405 if (seqnr)
406 *seqnr = state->seqnr;
407 if (blocks)
408 *blocks = state->blocks;
409 if (packets)
410 *packets = state->packets;
411 if (bytes)
412 *bytes = state->bytes;
413 }
414
415 void
packet_set_state(int mode,u_int32_t seqnr,u_int64_t blocks,u_int32_t packets,u_int64_t bytes)416 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
417 u_int64_t bytes)
418 {
419 struct packet_state *state;
420
421 state = (mode == MODE_IN) ?
422 &active_state->p_read : &active_state->p_send;
423 state->seqnr = seqnr;
424 state->blocks = blocks;
425 state->packets = packets;
426 state->bytes = bytes;
427 }
428
429 /* returns 1 if connection is via ipv4 */
430
431 int
packet_connection_is_ipv4(void)432 packet_connection_is_ipv4(void)
433 {
434 struct sockaddr_storage to;
435 socklen_t tolen = sizeof(to);
436
437 memset(&to, 0, sizeof(to));
438 if (getsockname(active_state->connection_out, (struct sockaddr *)&to,
439 &tolen) < 0)
440 return 0;
441 if (to.ss_family != AF_INET)
442 return 0;
443 return 1;
444 }
445
446 /* Sets the connection into non-blocking mode. */
447
448 void
packet_set_nonblocking(void)449 packet_set_nonblocking(void)
450 {
451 /* Set the socket into non-blocking mode. */
452 set_nonblock(active_state->connection_in);
453
454 if (active_state->connection_out != active_state->connection_in)
455 set_nonblock(active_state->connection_out);
456 }
457
458 /* Returns the socket used for reading. */
459
460 int
packet_get_connection_in(void)461 packet_get_connection_in(void)
462 {
463 return active_state->connection_in;
464 }
465
466 /* Returns the descriptor used for writing. */
467
468 int
packet_get_connection_out(void)469 packet_get_connection_out(void)
470 {
471 return active_state->connection_out;
472 }
473
474 /* Closes the connection and clears and frees internal data structures. */
475
476 void
packet_close(void)477 packet_close(void)
478 {
479 if (!active_state->initialized)
480 return;
481 active_state->initialized = 0;
482 if (active_state->connection_in == active_state->connection_out) {
483 shutdown(active_state->connection_out, SHUT_RDWR);
484 close(active_state->connection_out);
485 } else {
486 close(active_state->connection_in);
487 close(active_state->connection_out);
488 }
489 buffer_free(&active_state->input);
490 buffer_free(&active_state->output);
491 buffer_free(&active_state->outgoing_packet);
492 buffer_free(&active_state->incoming_packet);
493 if (active_state->compression_buffer_ready) {
494 buffer_free(&active_state->compression_buffer);
495 buffer_compress_uninit();
496 }
497 cipher_cleanup(&active_state->send_context);
498 cipher_cleanup(&active_state->receive_context);
499 }
500
501 /* Sets remote side protocol flags. */
502
503 void
packet_set_protocol_flags(u_int protocol_flags)504 packet_set_protocol_flags(u_int protocol_flags)
505 {
506 active_state->remote_protocol_flags = protocol_flags;
507 }
508
509 /* Returns the remote protocol flags set earlier by the above function. */
510
511 u_int
packet_get_protocol_flags(void)512 packet_get_protocol_flags(void)
513 {
514 return active_state->remote_protocol_flags;
515 }
516
517 /*
518 * Starts packet compression from the next packet on in both directions.
519 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
520 */
521
522 static void
packet_init_compression(void)523 packet_init_compression(void)
524 {
525 if (active_state->compression_buffer_ready == 1)
526 return;
527 active_state->compression_buffer_ready = 1;
528 buffer_init(&active_state->compression_buffer);
529 }
530
531 void
packet_start_compression(int level)532 packet_start_compression(int level)
533 {
534 if (active_state->packet_compression && !compat20)
535 fatal("Compression already enabled.");
536 active_state->packet_compression = 1;
537 packet_init_compression();
538 buffer_compress_init_send(level);
539 buffer_compress_init_recv();
540 }
541
542 /*
543 * Causes any further packets to be encrypted using the given key. The same
544 * key is used for both sending and reception. However, both directions are
545 * encrypted independently of each other.
546 */
547
548 void
packet_set_encryption_key(const u_char * key,u_int keylen,int number)549 packet_set_encryption_key(const u_char *key, u_int keylen,
550 int number)
551 {
552 Cipher *cipher = cipher_by_number(number);
553
554 if (cipher == NULL)
555 fatal("packet_set_encryption_key: unknown cipher number %d", number);
556 if (keylen < 20)
557 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
558 if (keylen > SSH_SESSION_KEY_LENGTH)
559 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
560 memcpy(active_state->ssh1_key, key, keylen);
561 active_state->ssh1_keylen = keylen;
562 cipher_init(&active_state->send_context, cipher, key, keylen, NULL,
563 0, CIPHER_ENCRYPT);
564 cipher_init(&active_state->receive_context, cipher, key, keylen, NULL,
565 0, CIPHER_DECRYPT);
566 }
567
568 u_int
packet_get_encryption_key(u_char * key)569 packet_get_encryption_key(u_char *key)
570 {
571 if (key == NULL)
572 return (active_state->ssh1_keylen);
573 memcpy(key, active_state->ssh1_key, active_state->ssh1_keylen);
574 return (active_state->ssh1_keylen);
575 }
576
577 /* Start constructing a packet to send. */
578 void
packet_start(u_char type)579 packet_start(u_char type)
580 {
581 u_char buf[9];
582 int len;
583
584 DBG(debug("packet_start[%d]", type));
585 len = compat20 ? 6 : 9;
586 memset(buf, 0, len - 1);
587 buf[len - 1] = type;
588 buffer_clear(&active_state->outgoing_packet);
589 buffer_append(&active_state->outgoing_packet, buf, len);
590 }
591
592 /* Append payload. */
593 void
packet_put_char(int value)594 packet_put_char(int value)
595 {
596 char ch = value;
597
598 buffer_append(&active_state->outgoing_packet, &ch, 1);
599 }
600
601 void
packet_put_int(u_int value)602 packet_put_int(u_int value)
603 {
604 buffer_put_int(&active_state->outgoing_packet, value);
605 }
606
607 void
packet_put_int64(u_int64_t value)608 packet_put_int64(u_int64_t value)
609 {
610 buffer_put_int64(&active_state->outgoing_packet, value);
611 }
612
613 void
packet_put_string(const void * buf,u_int len)614 packet_put_string(const void *buf, u_int len)
615 {
616 buffer_put_string(&active_state->outgoing_packet, buf, len);
617 }
618
619 void
packet_put_cstring(const char * str)620 packet_put_cstring(const char *str)
621 {
622 buffer_put_cstring(&active_state->outgoing_packet, str);
623 }
624
625 void
packet_put_raw(const void * buf,u_int len)626 packet_put_raw(const void *buf, u_int len)
627 {
628 buffer_append(&active_state->outgoing_packet, buf, len);
629 }
630
631 void
packet_put_bignum(BIGNUM * value)632 packet_put_bignum(BIGNUM * value)
633 {
634 buffer_put_bignum(&active_state->outgoing_packet, value);
635 }
636
637 void
packet_put_bignum2(BIGNUM * value)638 packet_put_bignum2(BIGNUM * value)
639 {
640 buffer_put_bignum2(&active_state->outgoing_packet, value);
641 }
642
643 /*
644 * Finalizes and sends the packet. If the encryption key has been set,
645 * encrypts the packet before sending.
646 */
647
648 static void
packet_send1(void)649 packet_send1(void)
650 {
651 u_char buf[8], *cp;
652 int i, padding, len;
653 u_int checksum;
654 u_int32_t rnd = 0;
655
656 /*
657 * If using packet compression, compress the payload of the outgoing
658 * packet.
659 */
660 if (active_state->packet_compression) {
661 buffer_clear(&active_state->compression_buffer);
662 /* Skip padding. */
663 buffer_consume(&active_state->outgoing_packet, 8);
664 /* padding */
665 buffer_append(&active_state->compression_buffer,
666 NULs, 8);
667 buffer_compress(&active_state->outgoing_packet,
668 &active_state->compression_buffer);
669 buffer_clear(&active_state->outgoing_packet);
670 buffer_append(&active_state->outgoing_packet,
671 buffer_ptr(&active_state->compression_buffer),
672 buffer_len(&active_state->compression_buffer));
673 }
674 /* Compute packet length without padding (add checksum, remove padding). */
675 len = buffer_len(&active_state->outgoing_packet) + 4 - 8;
676
677 /* Insert padding. Initialized to zero in packet_start1() */
678 padding = 8 - len % 8;
679 if (!active_state->send_context.plaintext) {
680 cp = buffer_ptr(&active_state->outgoing_packet);
681 for (i = 0; i < padding; i++) {
682 if (i % 4 == 0)
683 rnd = arc4random();
684 cp[7 - i] = rnd & 0xff;
685 rnd >>= 8;
686 }
687 }
688 buffer_consume(&active_state->outgoing_packet, 8 - padding);
689
690 /* Add check bytes. */
691 checksum = ssh_crc32(buffer_ptr(&active_state->outgoing_packet),
692 buffer_len(&active_state->outgoing_packet));
693 put_u32(buf, checksum);
694 buffer_append(&active_state->outgoing_packet, buf, 4);
695
696 #ifdef PACKET_DEBUG
697 fprintf(stderr, "packet_send plain: ");
698 buffer_dump(&active_state->outgoing_packet);
699 #endif
700
701 /* Append to output. */
702 put_u32(buf, len);
703 buffer_append(&active_state->output, buf, 4);
704 cp = buffer_append_space(&active_state->output,
705 buffer_len(&active_state->outgoing_packet));
706 cipher_crypt(&active_state->send_context, cp,
707 buffer_ptr(&active_state->outgoing_packet),
708 buffer_len(&active_state->outgoing_packet));
709
710 #ifdef PACKET_DEBUG
711 fprintf(stderr, "encrypted: ");
712 buffer_dump(&active_state->output);
713 #endif
714 active_state->p_send.packets++;
715 active_state->p_send.bytes += len +
716 buffer_len(&active_state->outgoing_packet);
717 buffer_clear(&active_state->outgoing_packet);
718
719 /*
720 * Note that the packet is now only buffered in output. It won't be
721 * actually sent until packet_write_wait or packet_write_poll is
722 * called.
723 */
724 }
725
726 void
set_newkeys(int mode)727 set_newkeys(int mode)
728 {
729 Enc *enc;
730 Mac *mac;
731 Comp *comp;
732 CipherContext *cc;
733 u_int64_t *max_blocks;
734 int crypt_type;
735
736 debug2("set_newkeys: mode %d", mode);
737
738 if (mode == MODE_OUT) {
739 cc = &active_state->send_context;
740 crypt_type = CIPHER_ENCRYPT;
741 active_state->p_send.packets = active_state->p_send.blocks = 0;
742 max_blocks = &active_state->max_blocks_out;
743 } else {
744 cc = &active_state->receive_context;
745 crypt_type = CIPHER_DECRYPT;
746 active_state->p_read.packets = active_state->p_read.blocks = 0;
747 max_blocks = &active_state->max_blocks_in;
748 }
749 if (active_state->newkeys[mode] != NULL) {
750 debug("set_newkeys: rekeying");
751 cipher_cleanup(cc);
752 enc = &active_state->newkeys[mode]->enc;
753 mac = &active_state->newkeys[mode]->mac;
754 comp = &active_state->newkeys[mode]->comp;
755 mac_clear(mac);
756 xfree(enc->name);
757 xfree(enc->iv);
758 xfree(enc->key);
759 xfree(mac->name);
760 xfree(mac->key);
761 xfree(comp->name);
762 xfree(active_state->newkeys[mode]);
763 }
764 active_state->newkeys[mode] = kex_get_newkeys(mode);
765 if (active_state->newkeys[mode] == NULL)
766 fatal("newkeys: no keys for mode %d", mode);
767 enc = &active_state->newkeys[mode]->enc;
768 mac = &active_state->newkeys[mode]->mac;
769 comp = &active_state->newkeys[mode]->comp;
770 if (mac_init(mac) == 0)
771 mac->enabled = 1;
772 DBG(debug("cipher_init_context: %d", mode));
773 cipher_init(cc, enc->cipher, enc->key, enc->key_len,
774 enc->iv, enc->block_size, crypt_type);
775 /* Deleting the keys does not gain extra security */
776 /* memset(enc->iv, 0, enc->block_size);
777 memset(enc->key, 0, enc->key_len);
778 memset(mac->key, 0, mac->key_len); */
779 if ((comp->type == COMP_ZLIB ||
780 (comp->type == COMP_DELAYED &&
781 active_state->after_authentication)) && comp->enabled == 0) {
782 packet_init_compression();
783 if (mode == MODE_OUT)
784 buffer_compress_init_send(6);
785 else
786 buffer_compress_init_recv();
787 comp->enabled = 1;
788 }
789 /*
790 * The 2^(blocksize*2) limit is too expensive for 3DES,
791 * blowfish, etc, so enforce a 1GB limit for small blocksizes.
792 */
793 if (enc->block_size >= 16)
794 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
795 else
796 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
797 if (active_state->rekey_limit)
798 *max_blocks = MIN(*max_blocks,
799 active_state->rekey_limit / enc->block_size);
800 }
801
802 /*
803 * Delayed compression for SSH2 is enabled after authentication:
804 * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
805 * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
806 */
807 static void
packet_enable_delayed_compress(void)808 packet_enable_delayed_compress(void)
809 {
810 Comp *comp = NULL;
811 int mode;
812
813 /*
814 * Remember that we are past the authentication step, so rekeying
815 * with COMP_DELAYED will turn on compression immediately.
816 */
817 active_state->after_authentication = 1;
818 for (mode = 0; mode < MODE_MAX; mode++) {
819 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
820 if (active_state->newkeys[mode] == NULL)
821 continue;
822 comp = &active_state->newkeys[mode]->comp;
823 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
824 packet_init_compression();
825 if (mode == MODE_OUT)
826 buffer_compress_init_send(6);
827 else
828 buffer_compress_init_recv();
829 comp->enabled = 1;
830 }
831 }
832 }
833
834 /*
835 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
836 */
837 static void
packet_send2_wrapped(void)838 packet_send2_wrapped(void)
839 {
840 u_char type, *cp, *macbuf = NULL;
841 u_char padlen, pad;
842 u_int packet_length = 0;
843 u_int len;
844 Enc *enc = NULL;
845 Mac *mac = NULL;
846 Comp *comp = NULL;
847 int block_size;
848
849 if (active_state->newkeys[MODE_OUT] != NULL) {
850 enc = &active_state->newkeys[MODE_OUT]->enc;
851 mac = &active_state->newkeys[MODE_OUT]->mac;
852 comp = &active_state->newkeys[MODE_OUT]->comp;
853 }
854 block_size = enc ? enc->block_size : 8;
855
856 cp = buffer_ptr(&active_state->outgoing_packet);
857 type = cp[5];
858
859 #ifdef PACKET_DEBUG
860 fprintf(stderr, "plain: ");
861 buffer_dump(&active_state->outgoing_packet);
862 #endif
863
864 if (comp && comp->enabled) {
865 len = buffer_len(&active_state->outgoing_packet);
866 /* skip header, compress only payload */
867 buffer_consume(&active_state->outgoing_packet, 5);
868 buffer_clear(&active_state->compression_buffer);
869 buffer_compress(&active_state->outgoing_packet,
870 &active_state->compression_buffer);
871 buffer_clear(&active_state->outgoing_packet);
872 buffer_append(&active_state->outgoing_packet, NULs, 5);
873 buffer_append(&active_state->outgoing_packet,
874 buffer_ptr(&active_state->compression_buffer),
875 buffer_len(&active_state->compression_buffer));
876 DBG(debug("compression: raw %d compressed %d", len,
877 buffer_len(&active_state->outgoing_packet)));
878 }
879
880 /* sizeof (packet_len + pad_len + payload) */
881 len = buffer_len(&active_state->outgoing_packet);
882
883 /*
884 * calc size of padding, alloc space, get random data,
885 * minimum padding is 4 bytes
886 */
887 padlen = block_size - (len % block_size);
888 if (padlen < 4)
889 padlen += block_size;
890 if (active_state->extra_pad) {
891 /* will wrap if extra_pad+padlen > 255 */
892 active_state->extra_pad =
893 roundup(active_state->extra_pad, block_size);
894 pad = active_state->extra_pad -
895 ((len + padlen) % active_state->extra_pad);
896 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
897 pad, len, padlen, active_state->extra_pad);
898 padlen += pad;
899 active_state->extra_pad = 0;
900 }
901 cp = buffer_append_space(&active_state->outgoing_packet, padlen);
902 if (enc && !active_state->send_context.plaintext) {
903 /* random padding */
904 arc4random_buf(cp, padlen);
905 } else {
906 /* clear padding */
907 memset(cp, 0, padlen);
908 }
909 /* packet_length includes payload, padding and padding length field */
910 packet_length = buffer_len(&active_state->outgoing_packet) - 4;
911 cp = buffer_ptr(&active_state->outgoing_packet);
912 put_u32(cp, packet_length);
913 cp[4] = padlen;
914 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
915
916 /* compute MAC over seqnr and packet(length fields, payload, padding) */
917 if (mac && mac->enabled) {
918 macbuf = mac_compute(mac, active_state->p_send.seqnr,
919 buffer_ptr(&active_state->outgoing_packet),
920 buffer_len(&active_state->outgoing_packet));
921 DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
922 }
923 /* encrypt packet and append to output buffer. */
924 cp = buffer_append_space(&active_state->output,
925 buffer_len(&active_state->outgoing_packet));
926 cipher_crypt(&active_state->send_context, cp,
927 buffer_ptr(&active_state->outgoing_packet),
928 buffer_len(&active_state->outgoing_packet));
929 /* append unencrypted MAC */
930 if (mac && mac->enabled)
931 buffer_append(&active_state->output, macbuf, mac->mac_len);
932 #ifdef PACKET_DEBUG
933 fprintf(stderr, "encrypted: ");
934 buffer_dump(&active_state->output);
935 #endif
936 /* increment sequence number for outgoing packets */
937 if (++active_state->p_send.seqnr == 0)
938 logit("outgoing seqnr wraps around");
939 if (++active_state->p_send.packets == 0)
940 if (!(datafellows & SSH_BUG_NOREKEY))
941 fatal("XXX too many packets with same key");
942 active_state->p_send.blocks += (packet_length + 4) / block_size;
943 active_state->p_send.bytes += packet_length + 4;
944 buffer_clear(&active_state->outgoing_packet);
945
946 if (type == SSH2_MSG_NEWKEYS)
947 set_newkeys(MODE_OUT);
948 else if (type == SSH2_MSG_USERAUTH_SUCCESS && active_state->server_side)
949 packet_enable_delayed_compress();
950 }
951
952 static void
packet_send2(void)953 packet_send2(void)
954 {
955 struct packet *p;
956 u_char type, *cp;
957
958 cp = buffer_ptr(&active_state->outgoing_packet);
959 type = cp[5];
960
961 /* during rekeying we can only send key exchange messages */
962 if (active_state->rekeying) {
963 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
964 (type <= SSH2_MSG_TRANSPORT_MAX))) {
965 debug("enqueue packet: %u", type);
966 p = xmalloc(sizeof(*p));
967 p->type = type;
968 memcpy(&p->payload, &active_state->outgoing_packet,
969 sizeof(Buffer));
970 buffer_init(&active_state->outgoing_packet);
971 TAILQ_INSERT_TAIL(&active_state->outgoing, p, next);
972 return;
973 }
974 }
975
976 /* rekeying starts with sending KEXINIT */
977 if (type == SSH2_MSG_KEXINIT)
978 active_state->rekeying = 1;
979
980 packet_send2_wrapped();
981
982 /* after a NEWKEYS message we can send the complete queue */
983 if (type == SSH2_MSG_NEWKEYS) {
984 active_state->rekeying = 0;
985 while ((p = TAILQ_FIRST(&active_state->outgoing))) {
986 type = p->type;
987 debug("dequeue packet: %u", type);
988 buffer_free(&active_state->outgoing_packet);
989 memcpy(&active_state->outgoing_packet, &p->payload,
990 sizeof(Buffer));
991 TAILQ_REMOVE(&active_state->outgoing, p, next);
992 xfree(p);
993 packet_send2_wrapped();
994 }
995 }
996 }
997
998 void
packet_send(void)999 packet_send(void)
1000 {
1001 if (compat20)
1002 packet_send2();
1003 else
1004 packet_send1();
1005 DBG(debug("packet_send done"));
1006 }
1007
1008 /*
1009 * Waits until a packet has been received, and returns its type. Note that
1010 * no other data is processed until this returns, so this function should not
1011 * be used during the interactive session.
1012 */
1013
1014 int
packet_read_seqnr(u_int32_t * seqnr_p)1015 packet_read_seqnr(u_int32_t *seqnr_p)
1016 {
1017 int type, len, ret, ms_remain, cont;
1018 fd_set *setp;
1019 char buf[8192];
1020 struct timeval timeout, start, *timeoutp = NULL;
1021
1022 DBG(debug("packet_read()"));
1023
1024 setp = (fd_set *)xcalloc(howmany(active_state->connection_in + 1,
1025 NFDBITS), sizeof(fd_mask));
1026
1027 /* Since we are blocking, ensure that all written packets have been sent. */
1028 packet_write_wait();
1029
1030 /* Stay in the loop until we have received a complete packet. */
1031 for (;;) {
1032 /* Try to read a packet from the buffer. */
1033 type = packet_read_poll_seqnr(seqnr_p);
1034 if (!compat20 && (
1035 type == SSH_SMSG_SUCCESS
1036 || type == SSH_SMSG_FAILURE
1037 || type == SSH_CMSG_EOF
1038 || type == SSH_CMSG_EXIT_CONFIRMATION))
1039 packet_check_eom();
1040 /* If we got a packet, return it. */
1041 if (type != SSH_MSG_NONE) {
1042 xfree(setp);
1043 return type;
1044 }
1045 /*
1046 * Otherwise, wait for some data to arrive, add it to the
1047 * buffer, and try again.
1048 */
1049 memset(setp, 0, howmany(active_state->connection_in + 1,
1050 NFDBITS) * sizeof(fd_mask));
1051 FD_SET(active_state->connection_in, setp);
1052
1053 if (active_state->packet_timeout_ms > 0) {
1054 ms_remain = active_state->packet_timeout_ms;
1055 timeoutp = &timeout;
1056 }
1057 /* Wait for some data to arrive. */
1058 for (;;) {
1059 if (active_state->packet_timeout_ms != -1) {
1060 ms_to_timeval(&timeout, ms_remain);
1061 gettimeofday(&start, NULL);
1062 }
1063 if ((ret = select(active_state->connection_in + 1, setp,
1064 NULL, NULL, timeoutp)) >= 0)
1065 break;
1066 if (errno != EAGAIN && errno != EINTR)
1067 break;
1068 if (active_state->packet_timeout_ms == -1)
1069 continue;
1070 ms_subtract_diff(&start, &ms_remain);
1071 if (ms_remain <= 0) {
1072 ret = 0;
1073 break;
1074 }
1075 }
1076 if (ret == 0) {
1077 logit("Connection to %.200s timed out while "
1078 "waiting to read", get_remote_ipaddr());
1079 cleanup_exit(255);
1080 }
1081 /* Read data from the socket. */
1082 do {
1083 cont = 0;
1084 len = roaming_read(active_state->connection_in, buf,
1085 sizeof(buf), &cont);
1086 } while (len == 0 && cont);
1087 if (len == 0) {
1088 logit("Connection closed by %.200s", get_remote_ipaddr());
1089 cleanup_exit(255);
1090 }
1091 if (len < 0)
1092 fatal("Read from socket failed: %.100s", strerror(errno));
1093 /* Append it to the buffer. */
1094 packet_process_incoming(buf, len);
1095 }
1096 /* NOTREACHED */
1097 }
1098
1099 int
packet_read(void)1100 packet_read(void)
1101 {
1102 return packet_read_seqnr(NULL);
1103 }
1104
1105 /*
1106 * Waits until a packet has been received, verifies that its type matches
1107 * that given, and gives a fatal error and exits if there is a mismatch.
1108 */
1109
1110 void
packet_read_expect(int expected_type)1111 packet_read_expect(int expected_type)
1112 {
1113 int type;
1114
1115 type = packet_read();
1116 if (type != expected_type)
1117 packet_disconnect("Protocol error: expected packet type %d, got %d",
1118 expected_type, type);
1119 }
1120
1121 /* Checks if a full packet is available in the data received so far via
1122 * packet_process_incoming. If so, reads the packet; otherwise returns
1123 * SSH_MSG_NONE. This does not wait for data from the connection.
1124 *
1125 * SSH_MSG_DISCONNECT is handled specially here. Also,
1126 * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1127 * to higher levels.
1128 */
1129
1130 static int
packet_read_poll1(void)1131 packet_read_poll1(void)
1132 {
1133 u_int len, padded_len;
1134 u_char *cp, type;
1135 u_int checksum, stored_checksum;
1136
1137 /* Check if input size is less than minimum packet size. */
1138 if (buffer_len(&active_state->input) < 4 + 8)
1139 return SSH_MSG_NONE;
1140 /* Get length of incoming packet. */
1141 cp = buffer_ptr(&active_state->input);
1142 len = get_u32(cp);
1143 if (len < 1 + 2 + 2 || len > 256 * 1024)
1144 packet_disconnect("Bad packet length %u.", len);
1145 padded_len = (len + 8) & ~7;
1146
1147 /* Check if the packet has been entirely received. */
1148 if (buffer_len(&active_state->input) < 4 + padded_len)
1149 return SSH_MSG_NONE;
1150
1151 /* The entire packet is in buffer. */
1152
1153 /* Consume packet length. */
1154 buffer_consume(&active_state->input, 4);
1155
1156 /*
1157 * Cryptographic attack detector for ssh
1158 * (C)1998 CORE-SDI, Buenos Aires Argentina
1159 * Ariel Futoransky(futo@core-sdi.com)
1160 */
1161 if (!active_state->receive_context.plaintext) {
1162 switch (detect_attack(buffer_ptr(&active_state->input),
1163 padded_len)) {
1164 case DEATTACK_DETECTED:
1165 packet_disconnect("crc32 compensation attack: "
1166 "network attack detected");
1167 case DEATTACK_DOS_DETECTED:
1168 packet_disconnect("deattack denial of "
1169 "service detected");
1170 }
1171 }
1172
1173 /* Decrypt data to incoming_packet. */
1174 buffer_clear(&active_state->incoming_packet);
1175 cp = buffer_append_space(&active_state->incoming_packet, padded_len);
1176 cipher_crypt(&active_state->receive_context, cp,
1177 buffer_ptr(&active_state->input), padded_len);
1178
1179 buffer_consume(&active_state->input, padded_len);
1180
1181 #ifdef PACKET_DEBUG
1182 fprintf(stderr, "read_poll plain: ");
1183 buffer_dump(&active_state->incoming_packet);
1184 #endif
1185
1186 /* Compute packet checksum. */
1187 checksum = ssh_crc32(buffer_ptr(&active_state->incoming_packet),
1188 buffer_len(&active_state->incoming_packet) - 4);
1189
1190 /* Skip padding. */
1191 buffer_consume(&active_state->incoming_packet, 8 - len % 8);
1192
1193 /* Test check bytes. */
1194 if (len != buffer_len(&active_state->incoming_packet))
1195 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1196 len, buffer_len(&active_state->incoming_packet));
1197
1198 cp = (u_char *)buffer_ptr(&active_state->incoming_packet) + len - 4;
1199 stored_checksum = get_u32(cp);
1200 if (checksum != stored_checksum)
1201 packet_disconnect("Corrupted check bytes on input.");
1202 buffer_consume_end(&active_state->incoming_packet, 4);
1203
1204 if (active_state->packet_compression) {
1205 buffer_clear(&active_state->compression_buffer);
1206 buffer_uncompress(&active_state->incoming_packet,
1207 &active_state->compression_buffer);
1208 buffer_clear(&active_state->incoming_packet);
1209 buffer_append(&active_state->incoming_packet,
1210 buffer_ptr(&active_state->compression_buffer),
1211 buffer_len(&active_state->compression_buffer));
1212 }
1213 active_state->p_read.packets++;
1214 active_state->p_read.bytes += padded_len + 4;
1215 type = buffer_get_char(&active_state->incoming_packet);
1216 if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1217 packet_disconnect("Invalid ssh1 packet type: %d", type);
1218 return type;
1219 }
1220
1221 static int
packet_read_poll2(u_int32_t * seqnr_p)1222 packet_read_poll2(u_int32_t *seqnr_p)
1223 {
1224 u_int padlen, need;
1225 u_char *macbuf, *cp, type;
1226 u_int maclen, block_size;
1227 Enc *enc = NULL;
1228 Mac *mac = NULL;
1229 Comp *comp = NULL;
1230
1231 if (active_state->packet_discard)
1232 return SSH_MSG_NONE;
1233
1234 if (active_state->newkeys[MODE_IN] != NULL) {
1235 enc = &active_state->newkeys[MODE_IN]->enc;
1236 mac = &active_state->newkeys[MODE_IN]->mac;
1237 comp = &active_state->newkeys[MODE_IN]->comp;
1238 }
1239 maclen = mac && mac->enabled ? mac->mac_len : 0;
1240 block_size = enc ? enc->block_size : 8;
1241
1242 if (active_state->packlen == 0) {
1243 /*
1244 * check if input size is less than the cipher block size,
1245 * decrypt first block and extract length of incoming packet
1246 */
1247 if (buffer_len(&active_state->input) < block_size)
1248 return SSH_MSG_NONE;
1249 buffer_clear(&active_state->incoming_packet);
1250 cp = buffer_append_space(&active_state->incoming_packet,
1251 block_size);
1252 cipher_crypt(&active_state->receive_context, cp,
1253 buffer_ptr(&active_state->input), block_size);
1254 cp = buffer_ptr(&active_state->incoming_packet);
1255 active_state->packlen = get_u32(cp);
1256 if (active_state->packlen < 1 + 4 ||
1257 active_state->packlen > PACKET_MAX_SIZE) {
1258 #ifdef PACKET_DEBUG
1259 buffer_dump(&active_state->incoming_packet);
1260 #endif
1261 logit("Bad packet length %u.", active_state->packlen);
1262 packet_start_discard(enc, mac, active_state->packlen,
1263 PACKET_MAX_SIZE);
1264 return SSH_MSG_NONE;
1265 }
1266 DBG(debug("input: packet len %u", active_state->packlen+4));
1267 buffer_consume(&active_state->input, block_size);
1268 }
1269 /* we have a partial packet of block_size bytes */
1270 need = 4 + active_state->packlen - block_size;
1271 DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1272 need, maclen));
1273 if (need % block_size != 0) {
1274 logit("padding error: need %d block %d mod %d",
1275 need, block_size, need % block_size);
1276 packet_start_discard(enc, mac, active_state->packlen,
1277 PACKET_MAX_SIZE - block_size);
1278 return SSH_MSG_NONE;
1279 }
1280 /*
1281 * check if the entire packet has been received and
1282 * decrypt into incoming_packet
1283 */
1284 if (buffer_len(&active_state->input) < need + maclen)
1285 return SSH_MSG_NONE;
1286 #ifdef PACKET_DEBUG
1287 fprintf(stderr, "read_poll enc/full: ");
1288 buffer_dump(&active_state->input);
1289 #endif
1290 cp = buffer_append_space(&active_state->incoming_packet, need);
1291 cipher_crypt(&active_state->receive_context, cp,
1292 buffer_ptr(&active_state->input), need);
1293 buffer_consume(&active_state->input, need);
1294 /*
1295 * compute MAC over seqnr and packet,
1296 * increment sequence number for incoming packet
1297 */
1298 if (mac && mac->enabled) {
1299 macbuf = mac_compute(mac, active_state->p_read.seqnr,
1300 buffer_ptr(&active_state->incoming_packet),
1301 buffer_len(&active_state->incoming_packet));
1302 if (memcmp(macbuf, buffer_ptr(&active_state->input),
1303 mac->mac_len) != 0) {
1304 logit("Corrupted MAC on input.");
1305 if (need > PACKET_MAX_SIZE)
1306 fatal("internal error need %d", need);
1307 packet_start_discard(enc, mac, active_state->packlen,
1308 PACKET_MAX_SIZE - need);
1309 return SSH_MSG_NONE;
1310 }
1311
1312 DBG(debug("MAC #%d ok", active_state->p_read.seqnr));
1313 buffer_consume(&active_state->input, mac->mac_len);
1314 }
1315 /* XXX now it's safe to use fatal/packet_disconnect */
1316 if (seqnr_p != NULL)
1317 *seqnr_p = active_state->p_read.seqnr;
1318 if (++active_state->p_read.seqnr == 0)
1319 logit("incoming seqnr wraps around");
1320 if (++active_state->p_read.packets == 0)
1321 if (!(datafellows & SSH_BUG_NOREKEY))
1322 fatal("XXX too many packets with same key");
1323 active_state->p_read.blocks += (active_state->packlen + 4) / block_size;
1324 active_state->p_read.bytes += active_state->packlen + 4;
1325
1326 /* get padlen */
1327 cp = buffer_ptr(&active_state->incoming_packet);
1328 padlen = cp[4];
1329 DBG(debug("input: padlen %d", padlen));
1330 if (padlen < 4)
1331 packet_disconnect("Corrupted padlen %d on input.", padlen);
1332
1333 /* skip packet size + padlen, discard padding */
1334 buffer_consume(&active_state->incoming_packet, 4 + 1);
1335 buffer_consume_end(&active_state->incoming_packet, padlen);
1336
1337 DBG(debug("input: len before de-compress %d",
1338 buffer_len(&active_state->incoming_packet)));
1339 if (comp && comp->enabled) {
1340 buffer_clear(&active_state->compression_buffer);
1341 buffer_uncompress(&active_state->incoming_packet,
1342 &active_state->compression_buffer);
1343 buffer_clear(&active_state->incoming_packet);
1344 buffer_append(&active_state->incoming_packet,
1345 buffer_ptr(&active_state->compression_buffer),
1346 buffer_len(&active_state->compression_buffer));
1347 DBG(debug("input: len after de-compress %d",
1348 buffer_len(&active_state->incoming_packet)));
1349 }
1350 /*
1351 * get packet type, implies consume.
1352 * return length of payload (without type field)
1353 */
1354 type = buffer_get_char(&active_state->incoming_packet);
1355 if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1356 packet_disconnect("Invalid ssh2 packet type: %d", type);
1357 if (type == SSH2_MSG_NEWKEYS)
1358 set_newkeys(MODE_IN);
1359 else if (type == SSH2_MSG_USERAUTH_SUCCESS &&
1360 !active_state->server_side)
1361 packet_enable_delayed_compress();
1362 #ifdef PACKET_DEBUG
1363 fprintf(stderr, "read/plain[%d]:\r\n", type);
1364 buffer_dump(&active_state->incoming_packet);
1365 #endif
1366 /* reset for next packet */
1367 active_state->packlen = 0;
1368 return type;
1369 }
1370
1371 int
packet_read_poll_seqnr(u_int32_t * seqnr_p)1372 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1373 {
1374 u_int reason, seqnr;
1375 u_char type;
1376 char *msg;
1377
1378 for (;;) {
1379 if (compat20) {
1380 type = packet_read_poll2(seqnr_p);
1381 if (type) {
1382 active_state->keep_alive_timeouts = 0;
1383 DBG(debug("received packet type %d", type));
1384 }
1385 switch (type) {
1386 case SSH2_MSG_IGNORE:
1387 packet_consume_ignoremsg();
1388 debug3("Received SSH2_MSG_IGNORE");
1389 break;
1390 case SSH2_MSG_DEBUG:
1391 packet_get_char();
1392 msg = packet_get_string(NULL);
1393 debug("Remote: %.900s", msg);
1394 xfree(msg);
1395 msg = packet_get_string(NULL);
1396 xfree(msg);
1397 break;
1398 case SSH2_MSG_DISCONNECT:
1399 reason = packet_get_int();
1400 msg = packet_get_string(NULL);
1401 logit("Received disconnect from %s: %u: %.400s",
1402 get_remote_ipaddr(), reason, msg);
1403 xfree(msg);
1404 cleanup_exit(255);
1405 break;
1406 case SSH2_MSG_UNIMPLEMENTED:
1407 seqnr = packet_get_int();
1408 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1409 seqnr);
1410 break;
1411 default:
1412 return type;
1413 }
1414 } else {
1415 type = packet_read_poll1();
1416 switch (type) {
1417 case SSH_MSG_IGNORE:
1418 packet_consume_ignoremsg();
1419 break;
1420 case SSH_MSG_DEBUG:
1421 msg = packet_get_string(NULL);
1422 debug("Remote: %.900s", msg);
1423 xfree(msg);
1424 break;
1425 case SSH_MSG_DISCONNECT:
1426 msg = packet_get_string(NULL);
1427 logit("Received disconnect from %s: %.400s",
1428 get_remote_ipaddr(), msg);
1429 cleanup_exit(255);
1430 break;
1431 default:
1432 if (type) {
1433 DBG(debug("received packet type %d", type));
1434 }
1435 return type;
1436 }
1437 }
1438 }
1439 }
1440
1441 int
packet_read_poll(void)1442 packet_read_poll(void)
1443 {
1444 return packet_read_poll_seqnr(NULL);
1445 }
1446
1447 /*
1448 * Buffers the given amount of input characters. This is intended to be used
1449 * together with packet_read_poll.
1450 */
1451
1452 void
packet_process_incoming(const char * buf,u_int len)1453 packet_process_incoming(const char *buf, u_int len)
1454 {
1455 if (active_state->packet_discard) {
1456 active_state->keep_alive_timeouts = 0; /* ?? */
1457 if (len >= active_state->packet_discard)
1458 packet_stop_discard();
1459 active_state->packet_discard -= len;
1460 return;
1461 }
1462 buffer_append(&active_state->input, buf, len);
1463 }
1464
1465 /* Returns a character from the packet. */
1466
1467 u_int
packet_get_char(void)1468 packet_get_char(void)
1469 {
1470 char ch;
1471
1472 buffer_get(&active_state->incoming_packet, &ch, 1);
1473 return (u_char) ch;
1474 }
1475
1476 /* Returns an integer from the packet data. */
1477
1478 u_int
packet_get_int(void)1479 packet_get_int(void)
1480 {
1481 return buffer_get_int(&active_state->incoming_packet);
1482 }
1483
1484 /* Returns an 64 bit integer from the packet data. */
1485
1486 u_int64_t
packet_get_int64(void)1487 packet_get_int64(void)
1488 {
1489 return buffer_get_int64(&active_state->incoming_packet);
1490 }
1491
1492 /*
1493 * Returns an arbitrary precision integer from the packet data. The integer
1494 * must have been initialized before this call.
1495 */
1496
1497 void
packet_get_bignum(BIGNUM * value)1498 packet_get_bignum(BIGNUM * value)
1499 {
1500 buffer_get_bignum(&active_state->incoming_packet, value);
1501 }
1502
1503 void
packet_get_bignum2(BIGNUM * value)1504 packet_get_bignum2(BIGNUM * value)
1505 {
1506 buffer_get_bignum2(&active_state->incoming_packet, value);
1507 }
1508
1509 void *
packet_get_raw(u_int * length_ptr)1510 packet_get_raw(u_int *length_ptr)
1511 {
1512 u_int bytes = buffer_len(&active_state->incoming_packet);
1513
1514 if (length_ptr != NULL)
1515 *length_ptr = bytes;
1516 return buffer_ptr(&active_state->incoming_packet);
1517 }
1518
1519 int
packet_remaining(void)1520 packet_remaining(void)
1521 {
1522 return buffer_len(&active_state->incoming_packet);
1523 }
1524
1525 /*
1526 * Returns a string from the packet data. The string is allocated using
1527 * xmalloc; it is the responsibility of the calling program to free it when
1528 * no longer needed. The length_ptr argument may be NULL, or point to an
1529 * integer into which the length of the string is stored.
1530 */
1531
1532 void *
packet_get_string(u_int * length_ptr)1533 packet_get_string(u_int *length_ptr)
1534 {
1535 return buffer_get_string(&active_state->incoming_packet, length_ptr);
1536 }
1537
1538 void *
packet_get_string_ptr(u_int * length_ptr)1539 packet_get_string_ptr(u_int *length_ptr)
1540 {
1541 return buffer_get_string_ptr(&active_state->incoming_packet, length_ptr);
1542 }
1543
1544 /*
1545 * Sends a diagnostic message from the server to the client. This message
1546 * can be sent at any time (but not while constructing another message). The
1547 * message is printed immediately, but only if the client is being executed
1548 * in verbose mode. These messages are primarily intended to ease debugging
1549 * authentication problems. The length of the formatted message must not
1550 * exceed 1024 bytes. This will automatically call packet_write_wait.
1551 */
1552
1553 void
packet_send_debug(const char * fmt,...)1554 packet_send_debug(const char *fmt,...)
1555 {
1556 char buf[1024];
1557 va_list args;
1558
1559 if (compat20 && (datafellows & SSH_BUG_DEBUG))
1560 return;
1561
1562 va_start(args, fmt);
1563 vsnprintf(buf, sizeof(buf), fmt, args);
1564 va_end(args);
1565
1566 if (compat20) {
1567 packet_start(SSH2_MSG_DEBUG);
1568 packet_put_char(0); /* bool: always display */
1569 packet_put_cstring(buf);
1570 packet_put_cstring("");
1571 } else {
1572 packet_start(SSH_MSG_DEBUG);
1573 packet_put_cstring(buf);
1574 }
1575 packet_send();
1576 packet_write_wait();
1577 }
1578
1579 /*
1580 * Logs the error plus constructs and sends a disconnect packet, closes the
1581 * connection, and exits. This function never returns. The error message
1582 * should not contain a newline. The length of the formatted message must
1583 * not exceed 1024 bytes.
1584 */
1585
1586 void
packet_disconnect(const char * fmt,...)1587 packet_disconnect(const char *fmt,...)
1588 {
1589 char buf[1024];
1590 va_list args;
1591 static int disconnecting = 0;
1592
1593 if (disconnecting) /* Guard against recursive invocations. */
1594 fatal("packet_disconnect called recursively.");
1595 disconnecting = 1;
1596
1597 /*
1598 * Format the message. Note that the caller must make sure the
1599 * message is of limited size.
1600 */
1601 va_start(args, fmt);
1602 vsnprintf(buf, sizeof(buf), fmt, args);
1603 va_end(args);
1604
1605 /* Display the error locally */
1606 logit("Disconnecting: %.100s", buf);
1607
1608 /* Send the disconnect message to the other side, and wait for it to get sent. */
1609 if (compat20) {
1610 packet_start(SSH2_MSG_DISCONNECT);
1611 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1612 packet_put_cstring(buf);
1613 packet_put_cstring("");
1614 } else {
1615 packet_start(SSH_MSG_DISCONNECT);
1616 packet_put_cstring(buf);
1617 }
1618 packet_send();
1619 packet_write_wait();
1620
1621 /* Stop listening for connections. */
1622 channel_close_all();
1623
1624 /* Close the connection. */
1625 packet_close();
1626 cleanup_exit(255);
1627 }
1628
1629 /* Checks if there is any buffered output, and tries to write some of the output. */
1630
1631 void
packet_write_poll(void)1632 packet_write_poll(void)
1633 {
1634 int len = buffer_len(&active_state->output);
1635 int cont;
1636
1637 if (len > 0) {
1638 cont = 0;
1639 len = roaming_write(active_state->connection_out,
1640 buffer_ptr(&active_state->output), len, &cont);
1641 if (len == -1) {
1642 if (errno == EINTR || errno == EAGAIN)
1643 return;
1644 fatal("Write failed: %.100s", strerror(errno));
1645 }
1646 if (len == 0 && !cont)
1647 fatal("Write connection closed");
1648 buffer_consume(&active_state->output, len);
1649 }
1650 }
1651
1652 /*
1653 * Calls packet_write_poll repeatedly until all pending output data has been
1654 * written.
1655 */
1656
1657 void
packet_write_wait(void)1658 packet_write_wait(void)
1659 {
1660 fd_set *setp;
1661 int ret, ms_remain;
1662 struct timeval start, timeout, *timeoutp = NULL;
1663
1664 setp = (fd_set *)xcalloc(howmany(active_state->connection_out + 1,
1665 NFDBITS), sizeof(fd_mask));
1666 packet_write_poll();
1667 while (packet_have_data_to_write()) {
1668 memset(setp, 0, howmany(active_state->connection_out + 1,
1669 NFDBITS) * sizeof(fd_mask));
1670 FD_SET(active_state->connection_out, setp);
1671
1672 if (active_state->packet_timeout_ms > 0) {
1673 ms_remain = active_state->packet_timeout_ms;
1674 timeoutp = &timeout;
1675 }
1676 for (;;) {
1677 if (active_state->packet_timeout_ms != -1) {
1678 ms_to_timeval(&timeout, ms_remain);
1679 gettimeofday(&start, NULL);
1680 }
1681 if ((ret = select(active_state->connection_out + 1,
1682 NULL, setp, NULL, timeoutp)) >= 0)
1683 break;
1684 if (errno != EAGAIN && errno != EINTR)
1685 break;
1686 if (active_state->packet_timeout_ms == -1)
1687 continue;
1688 ms_subtract_diff(&start, &ms_remain);
1689 if (ms_remain <= 0) {
1690 ret = 0;
1691 break;
1692 }
1693 }
1694 if (ret == 0) {
1695 logit("Connection to %.200s timed out while "
1696 "waiting to write", get_remote_ipaddr());
1697 cleanup_exit(255);
1698 }
1699 packet_write_poll();
1700 }
1701 xfree(setp);
1702 }
1703
1704 /* Returns true if there is buffered data to write to the connection. */
1705
1706 int
packet_have_data_to_write(void)1707 packet_have_data_to_write(void)
1708 {
1709 return buffer_len(&active_state->output) != 0;
1710 }
1711
1712 /* Returns true if there is not too much data to write to the connection. */
1713
1714 int
packet_not_very_much_data_to_write(void)1715 packet_not_very_much_data_to_write(void)
1716 {
1717 if (active_state->interactive_mode)
1718 return buffer_len(&active_state->output) < 16384;
1719 else
1720 return buffer_len(&active_state->output) < 128 * 1024;
1721 }
1722
1723 static void
packet_set_tos(int interactive)1724 packet_set_tos(int interactive)
1725 {
1726 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1727
1728 if (!packet_connection_is_on_socket() ||
1729 !packet_connection_is_ipv4())
1730 return;
1731 if (setsockopt(active_state->connection_in, IPPROTO_IP, IP_TOS, &tos,
1732 sizeof(tos)) < 0)
1733 error("setsockopt IP_TOS %d: %.100s:",
1734 tos, strerror(errno));
1735 }
1736
1737 /* Informs that the current session is interactive. Sets IP flags for that. */
1738
1739 void
packet_set_interactive(int interactive)1740 packet_set_interactive(int interactive)
1741 {
1742 if (active_state->set_interactive_called)
1743 return;
1744 active_state->set_interactive_called = 1;
1745
1746 /* Record that we are in interactive mode. */
1747 active_state->interactive_mode = interactive;
1748
1749 /* Only set socket options if using a socket. */
1750 if (!packet_connection_is_on_socket())
1751 return;
1752 set_nodelay(active_state->connection_in);
1753 packet_set_tos(interactive);
1754 }
1755
1756 /* Returns true if the current connection is interactive. */
1757
1758 int
packet_is_interactive(void)1759 packet_is_interactive(void)
1760 {
1761 return active_state->interactive_mode;
1762 }
1763
1764 int
packet_set_maxsize(u_int s)1765 packet_set_maxsize(u_int s)
1766 {
1767 if (active_state->set_maxsize_called) {
1768 logit("packet_set_maxsize: called twice: old %d new %d",
1769 active_state->max_packet_size, s);
1770 return -1;
1771 }
1772 if (s < 4 * 1024 || s > 1024 * 1024) {
1773 logit("packet_set_maxsize: bad size %d", s);
1774 return -1;
1775 }
1776 active_state->set_maxsize_called = 1;
1777 debug("packet_set_maxsize: setting to %d", s);
1778 active_state->max_packet_size = s;
1779 return s;
1780 }
1781
1782 int
packet_inc_alive_timeouts(void)1783 packet_inc_alive_timeouts(void)
1784 {
1785 return ++active_state->keep_alive_timeouts;
1786 }
1787
1788 void
packet_set_alive_timeouts(int ka)1789 packet_set_alive_timeouts(int ka)
1790 {
1791 active_state->keep_alive_timeouts = ka;
1792 }
1793
1794 u_int
packet_get_maxsize(void)1795 packet_get_maxsize(void)
1796 {
1797 return active_state->max_packet_size;
1798 }
1799
1800 /* roundup current message to pad bytes */
1801 void
packet_add_padding(u_char pad)1802 packet_add_padding(u_char pad)
1803 {
1804 active_state->extra_pad = pad;
1805 }
1806
1807 /*
1808 * 9.2. Ignored Data Message
1809 *
1810 * byte SSH_MSG_IGNORE
1811 * string data
1812 *
1813 * All implementations MUST understand (and ignore) this message at any
1814 * time (after receiving the protocol version). No implementation is
1815 * required to send them. This message can be used as an additional
1816 * protection measure against advanced traffic analysis techniques.
1817 */
1818 void
packet_send_ignore(int nbytes)1819 packet_send_ignore(int nbytes)
1820 {
1821 u_int32_t rnd = 0;
1822 int i;
1823
1824 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1825 packet_put_int(nbytes);
1826 for (i = 0; i < nbytes; i++) {
1827 if (i % 4 == 0)
1828 rnd = arc4random();
1829 packet_put_char((u_char)rnd & 0xff);
1830 rnd >>= 8;
1831 }
1832 }
1833
1834 #define MAX_PACKETS (1U<<31)
1835 int
packet_need_rekeying(void)1836 packet_need_rekeying(void)
1837 {
1838 if (datafellows & SSH_BUG_NOREKEY)
1839 return 0;
1840 return
1841 (active_state->p_send.packets > MAX_PACKETS) ||
1842 (active_state->p_read.packets > MAX_PACKETS) ||
1843 (active_state->max_blocks_out &&
1844 (active_state->p_send.blocks > active_state->max_blocks_out)) ||
1845 (active_state->max_blocks_in &&
1846 (active_state->p_read.blocks > active_state->max_blocks_in));
1847 }
1848
1849 void
packet_set_rekey_limit(u_int32_t bytes)1850 packet_set_rekey_limit(u_int32_t bytes)
1851 {
1852 active_state->rekey_limit = bytes;
1853 }
1854
1855 void
packet_set_server(void)1856 packet_set_server(void)
1857 {
1858 active_state->server_side = 1;
1859 }
1860
1861 void
packet_set_authenticated(void)1862 packet_set_authenticated(void)
1863 {
1864 active_state->after_authentication = 1;
1865 }
1866
1867 void *
packet_get_input(void)1868 packet_get_input(void)
1869 {
1870 return (void *)&active_state->input;
1871 }
1872
1873 void *
packet_get_output(void)1874 packet_get_output(void)
1875 {
1876 return (void *)&active_state->output;
1877 }
1878
1879 void *
packet_get_newkeys(int mode)1880 packet_get_newkeys(int mode)
1881 {
1882 return (void *)active_state->newkeys[mode];
1883 }
1884
1885 /*
1886 * Save the state for the real connection, and use a separate state when
1887 * resuming a suspended connection.
1888 */
1889 void
packet_backup_state(void)1890 packet_backup_state(void)
1891 {
1892 struct session_state *tmp;
1893
1894 close(active_state->connection_in);
1895 active_state->connection_in = -1;
1896 close(active_state->connection_out);
1897 active_state->connection_out = -1;
1898 if (backup_state)
1899 tmp = backup_state;
1900 else
1901 tmp = alloc_session_state();
1902 backup_state = active_state;
1903 active_state = tmp;
1904 }
1905
1906 /*
1907 * Swap in the old state when resuming a connecion.
1908 */
1909 void
packet_restore_state(void)1910 packet_restore_state(void)
1911 {
1912 struct session_state *tmp;
1913 void *buf;
1914 u_int len;
1915
1916 tmp = backup_state;
1917 backup_state = active_state;
1918 active_state = tmp;
1919 active_state->connection_in = backup_state->connection_in;
1920 backup_state->connection_in = -1;
1921 active_state->connection_out = backup_state->connection_out;
1922 backup_state->connection_out = -1;
1923 len = buffer_len(&backup_state->input);
1924 if (len > 0) {
1925 buf = buffer_ptr(&backup_state->input);
1926 buffer_append(&active_state->input, buf, len);
1927 buffer_clear(&backup_state->input);
1928 add_recv_bytes(len);
1929 }
1930 }
1931
1932 static void
packet_consume_ignoremsg(void)1933 packet_consume_ignoremsg(void)
1934 {
1935 u_int n;
1936 u_int8_t *b;
1937
1938 if ((b = packet_get_raw(&n)) == NULL)
1939 return;
1940
1941 arc4random_pushb_fast(b, n);
1942 }
1943