1 /* $OpenBSD: packet.c,v 1.173 2011/05/06 21:14:05 djm Exp $ */
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * This file contains code implementing the packet protocol and communication
7 * with the other side. This same code is used both on client and server side.
8 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
14 *
15 *
16 * SSH2 packet format added by Markus Friedl.
17 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
18 *
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
21 * are met:
22 * 1. Redistributions of source code must retain the above copyright
23 * notice, this list of conditions and the following disclaimer.
24 * 2. Redistributions in binary form must reproduce the above copyright
25 * notice, this list of conditions and the following disclaimer in the
26 * documentation and/or other materials provided with the distribution.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38 */
39
40 #include "includes.h"
41
42 #include <sys/types.h>
43 #include "openbsd-compat/sys-queue.h"
44 #include <sys/param.h>
45 #include <sys/socket.h>
46 #ifdef HAVE_SYS_TIME_H
47 # include <sys/time.h>
48 #endif
49
50 #include <netinet/in.h>
51 #include <netinet/ip.h>
52 #include <arpa/inet.h>
53
54 #include <errno.h>
55 #include <stdarg.h>
56 #include <stdio.h>
57 #include <stdlib.h>
58 #include <string.h>
59 #include <unistd.h>
60 #include <signal.h>
61
62 #include "xmalloc.h"
63 #include "buffer.h"
64 #include "packet.h"
65 #include "crc32.h"
66 #include "compress.h"
67 #include "deattack.h"
68 #include "channels.h"
69 #include "compat.h"
70 #include "ssh1.h"
71 #include "ssh2.h"
72 #include "cipher.h"
73 #include "key.h"
74 #include "kex.h"
75 #include "mac.h"
76 #include "log.h"
77 #include "canohost.h"
78 #include "misc.h"
79 #include "ssh.h"
80 #include "roaming.h"
81
82 #ifdef PACKET_DEBUG
83 #define DBG(x) x
84 #else
85 #define DBG(x)
86 #endif
87
88 #define PACKET_MAX_SIZE (256 * 1024)
89
90 struct packet_state {
91 u_int32_t seqnr;
92 u_int32_t packets;
93 u_int64_t blocks;
94 u_int64_t bytes;
95 };
96
97 struct packet {
98 TAILQ_ENTRY(packet) next;
99 u_char type;
100 Buffer payload;
101 };
102
103 struct session_state {
104 /*
105 * This variable contains the file descriptors used for
106 * communicating with the other side. connection_in is used for
107 * reading; connection_out for writing. These can be the same
108 * descriptor, in which case it is assumed to be a socket.
109 */
110 int connection_in;
111 int connection_out;
112
113 /* Protocol flags for the remote side. */
114 u_int remote_protocol_flags;
115
116 /* Encryption context for receiving data. Only used for decryption. */
117 CipherContext receive_context;
118
119 /* Encryption context for sending data. Only used for encryption. */
120 CipherContext send_context;
121
122 /* Buffer for raw input data from the socket. */
123 Buffer input;
124
125 /* Buffer for raw output data going to the socket. */
126 Buffer output;
127
128 /* Buffer for the partial outgoing packet being constructed. */
129 Buffer outgoing_packet;
130
131 /* Buffer for the incoming packet currently being processed. */
132 Buffer incoming_packet;
133
134 /* Scratch buffer for packet compression/decompression. */
135 Buffer compression_buffer;
136 int compression_buffer_ready;
137
138 /*
139 * Flag indicating whether packet compression/decompression is
140 * enabled.
141 */
142 int packet_compression;
143
144 /* default maximum packet size */
145 u_int max_packet_size;
146
147 /* Flag indicating whether this module has been initialized. */
148 int initialized;
149
150 /* Set to true if the connection is interactive. */
151 int interactive_mode;
152
153 /* Set to true if we are the server side. */
154 int server_side;
155
156 /* Set to true if we are authenticated. */
157 int after_authentication;
158
159 int keep_alive_timeouts;
160
161 /* The maximum time that we will wait to send or receive a packet */
162 int packet_timeout_ms;
163
164 /* Session key information for Encryption and MAC */
165 Newkeys *newkeys[MODE_MAX];
166 struct packet_state p_read, p_send;
167
168 u_int64_t max_blocks_in, max_blocks_out;
169 u_int32_t rekey_limit;
170
171 /* Session key for protocol v1 */
172 u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
173 u_int ssh1_keylen;
174
175 /* roundup current message to extra_pad bytes */
176 u_char extra_pad;
177
178 /* XXX discard incoming data after MAC error */
179 u_int packet_discard;
180 Mac *packet_discard_mac;
181
182 /* Used in packet_read_poll2() */
183 u_int packlen;
184
185 /* Used in packet_send2 */
186 int rekeying;
187
188 /* Used in packet_set_interactive */
189 int set_interactive_called;
190
191 /* Used in packet_set_maxsize */
192 int set_maxsize_called;
193
194 TAILQ_HEAD(, packet) outgoing;
195 };
196
197 static struct session_state *active_state, *backup_state;
198
199 static struct session_state *
alloc_session_state(void)200 alloc_session_state(void)
201 {
202 struct session_state *s = xcalloc(1, sizeof(*s));
203
204 s->connection_in = -1;
205 s->connection_out = -1;
206 s->max_packet_size = 32768;
207 s->packet_timeout_ms = -1;
208 return s;
209 }
210
211 /*
212 * Sets the descriptors used for communication. Disables encryption until
213 * packet_set_encryption_key is called.
214 */
215 void
packet_set_connection(int fd_in,int fd_out)216 packet_set_connection(int fd_in, int fd_out)
217 {
218 Cipher *none = cipher_by_name("none");
219
220 if (none == NULL)
221 fatal("packet_set_connection: cannot load cipher 'none'");
222 if (active_state == NULL)
223 active_state = alloc_session_state();
224 active_state->connection_in = fd_in;
225 active_state->connection_out = fd_out;
226 cipher_init(&active_state->send_context, none, (const u_char *)"",
227 0, NULL, 0, CIPHER_ENCRYPT);
228 cipher_init(&active_state->receive_context, none, (const u_char *)"",
229 0, NULL, 0, CIPHER_DECRYPT);
230 active_state->newkeys[MODE_IN] = active_state->newkeys[MODE_OUT] = NULL;
231 if (!active_state->initialized) {
232 active_state->initialized = 1;
233 buffer_init(&active_state->input);
234 buffer_init(&active_state->output);
235 buffer_init(&active_state->outgoing_packet);
236 buffer_init(&active_state->incoming_packet);
237 TAILQ_INIT(&active_state->outgoing);
238 active_state->p_send.packets = active_state->p_read.packets = 0;
239 }
240 }
241
242 void
packet_set_timeout(int timeout,int count)243 packet_set_timeout(int timeout, int count)
244 {
245 if (timeout == 0 || count == 0) {
246 active_state->packet_timeout_ms = -1;
247 return;
248 }
249 if ((INT_MAX / 1000) / count < timeout)
250 active_state->packet_timeout_ms = INT_MAX;
251 else
252 active_state->packet_timeout_ms = timeout * count * 1000;
253 }
254
255 static void
packet_stop_discard(void)256 packet_stop_discard(void)
257 {
258 if (active_state->packet_discard_mac) {
259 char buf[1024];
260
261 memset(buf, 'a', sizeof(buf));
262 while (buffer_len(&active_state->incoming_packet) <
263 PACKET_MAX_SIZE)
264 buffer_append(&active_state->incoming_packet, buf,
265 sizeof(buf));
266 (void) mac_compute(active_state->packet_discard_mac,
267 active_state->p_read.seqnr,
268 buffer_ptr(&active_state->incoming_packet),
269 PACKET_MAX_SIZE);
270 }
271 logit("Finished discarding for %.200s", get_remote_ipaddr());
272 cleanup_exit(255);
273 }
274
275 static void
packet_start_discard(Enc * enc,Mac * mac,u_int packet_length,u_int discard)276 packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard)
277 {
278 if (enc == NULL || !cipher_is_cbc(enc->cipher))
279 packet_disconnect("Packet corrupt");
280 if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
281 active_state->packet_discard_mac = mac;
282 if (buffer_len(&active_state->input) >= discard)
283 packet_stop_discard();
284 active_state->packet_discard = discard -
285 buffer_len(&active_state->input);
286 }
287
288 /* Returns 1 if remote host is connected via socket, 0 if not. */
289
290 int
packet_connection_is_on_socket(void)291 packet_connection_is_on_socket(void)
292 {
293 struct sockaddr_storage from, to;
294 socklen_t fromlen, tolen;
295
296 /* filedescriptors in and out are the same, so it's a socket */
297 if (active_state->connection_in == active_state->connection_out)
298 return 1;
299 fromlen = sizeof(from);
300 memset(&from, 0, sizeof(from));
301 if (getpeername(active_state->connection_in, (struct sockaddr *)&from,
302 &fromlen) < 0)
303 return 0;
304 tolen = sizeof(to);
305 memset(&to, 0, sizeof(to));
306 if (getpeername(active_state->connection_out, (struct sockaddr *)&to,
307 &tolen) < 0)
308 return 0;
309 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
310 return 0;
311 if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
312 return 0;
313 return 1;
314 }
315
316 /*
317 * Exports an IV from the CipherContext required to export the key
318 * state back from the unprivileged child to the privileged parent
319 * process.
320 */
321
322 void
packet_get_keyiv(int mode,u_char * iv,u_int len)323 packet_get_keyiv(int mode, u_char *iv, u_int len)
324 {
325 CipherContext *cc;
326
327 if (mode == MODE_OUT)
328 cc = &active_state->send_context;
329 else
330 cc = &active_state->receive_context;
331
332 cipher_get_keyiv(cc, iv, len);
333 }
334
335 int
packet_get_keycontext(int mode,u_char * dat)336 packet_get_keycontext(int mode, u_char *dat)
337 {
338 CipherContext *cc;
339
340 if (mode == MODE_OUT)
341 cc = &active_state->send_context;
342 else
343 cc = &active_state->receive_context;
344
345 return (cipher_get_keycontext(cc, dat));
346 }
347
348 void
packet_set_keycontext(int mode,u_char * dat)349 packet_set_keycontext(int mode, u_char *dat)
350 {
351 CipherContext *cc;
352
353 if (mode == MODE_OUT)
354 cc = &active_state->send_context;
355 else
356 cc = &active_state->receive_context;
357
358 cipher_set_keycontext(cc, dat);
359 }
360
361 int
packet_get_keyiv_len(int mode)362 packet_get_keyiv_len(int mode)
363 {
364 CipherContext *cc;
365
366 if (mode == MODE_OUT)
367 cc = &active_state->send_context;
368 else
369 cc = &active_state->receive_context;
370
371 return (cipher_get_keyiv_len(cc));
372 }
373
374 void
packet_set_iv(int mode,u_char * dat)375 packet_set_iv(int mode, u_char *dat)
376 {
377 CipherContext *cc;
378
379 if (mode == MODE_OUT)
380 cc = &active_state->send_context;
381 else
382 cc = &active_state->receive_context;
383
384 cipher_set_keyiv(cc, dat);
385 }
386
387 int
packet_get_ssh1_cipher(void)388 packet_get_ssh1_cipher(void)
389 {
390 return (cipher_get_number(active_state->receive_context.cipher));
391 }
392
393 void
packet_get_state(int mode,u_int32_t * seqnr,u_int64_t * blocks,u_int32_t * packets,u_int64_t * bytes)394 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks,
395 u_int32_t *packets, u_int64_t *bytes)
396 {
397 struct packet_state *state;
398
399 state = (mode == MODE_IN) ?
400 &active_state->p_read : &active_state->p_send;
401 if (seqnr)
402 *seqnr = state->seqnr;
403 if (blocks)
404 *blocks = state->blocks;
405 if (packets)
406 *packets = state->packets;
407 if (bytes)
408 *bytes = state->bytes;
409 }
410
411 void
packet_set_state(int mode,u_int32_t seqnr,u_int64_t blocks,u_int32_t packets,u_int64_t bytes)412 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
413 u_int64_t bytes)
414 {
415 struct packet_state *state;
416
417 state = (mode == MODE_IN) ?
418 &active_state->p_read : &active_state->p_send;
419 state->seqnr = seqnr;
420 state->blocks = blocks;
421 state->packets = packets;
422 state->bytes = bytes;
423 }
424
425 static int
packet_connection_af(void)426 packet_connection_af(void)
427 {
428 struct sockaddr_storage to;
429 socklen_t tolen = sizeof(to);
430
431 memset(&to, 0, sizeof(to));
432 if (getsockname(active_state->connection_out, (struct sockaddr *)&to,
433 &tolen) < 0)
434 return 0;
435 if (to.ss_family == AF_INET)
436 return 1;
437 #ifdef IPV4_IN_IPV6
438 if (to.ss_family == AF_INET6 &&
439 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
440 return AF_INET;
441 #endif
442 return to.ss_family;
443 }
444
445 /* Sets the connection into non-blocking mode. */
446
447 void
packet_set_nonblocking(void)448 packet_set_nonblocking(void)
449 {
450 /* Set the socket into non-blocking mode. */
451 set_nonblock(active_state->connection_in);
452
453 if (active_state->connection_out != active_state->connection_in)
454 set_nonblock(active_state->connection_out);
455 }
456
457 /* Returns the socket used for reading. */
458
459 int
packet_get_connection_in(void)460 packet_get_connection_in(void)
461 {
462 return active_state->connection_in;
463 }
464
465 /* Returns the descriptor used for writing. */
466
467 int
packet_get_connection_out(void)468 packet_get_connection_out(void)
469 {
470 return active_state->connection_out;
471 }
472
473 /* Closes the connection and clears and frees internal data structures. */
474
475 void
packet_close(void)476 packet_close(void)
477 {
478 if (!active_state->initialized)
479 return;
480 active_state->initialized = 0;
481 if (active_state->connection_in == active_state->connection_out) {
482 shutdown(active_state->connection_out, SHUT_RDWR);
483 close(active_state->connection_out);
484 } else {
485 close(active_state->connection_in);
486 close(active_state->connection_out);
487 }
488 buffer_free(&active_state->input);
489 buffer_free(&active_state->output);
490 buffer_free(&active_state->outgoing_packet);
491 buffer_free(&active_state->incoming_packet);
492 if (active_state->compression_buffer_ready) {
493 buffer_free(&active_state->compression_buffer);
494 buffer_compress_uninit();
495 }
496 cipher_cleanup(&active_state->send_context);
497 cipher_cleanup(&active_state->receive_context);
498 }
499
500 /* Sets remote side protocol flags. */
501
502 void
packet_set_protocol_flags(u_int protocol_flags)503 packet_set_protocol_flags(u_int protocol_flags)
504 {
505 active_state->remote_protocol_flags = protocol_flags;
506 }
507
508 /* Returns the remote protocol flags set earlier by the above function. */
509
510 u_int
packet_get_protocol_flags(void)511 packet_get_protocol_flags(void)
512 {
513 return active_state->remote_protocol_flags;
514 }
515
516 /*
517 * Starts packet compression from the next packet on in both directions.
518 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
519 */
520
521 static void
packet_init_compression(void)522 packet_init_compression(void)
523 {
524 if (active_state->compression_buffer_ready == 1)
525 return;
526 active_state->compression_buffer_ready = 1;
527 buffer_init(&active_state->compression_buffer);
528 }
529
530 void
packet_start_compression(int level)531 packet_start_compression(int level)
532 {
533 if (active_state->packet_compression && !compat20)
534 fatal("Compression already enabled.");
535 active_state->packet_compression = 1;
536 packet_init_compression();
537 buffer_compress_init_send(level);
538 buffer_compress_init_recv();
539 }
540
541 /*
542 * Causes any further packets to be encrypted using the given key. The same
543 * key is used for both sending and reception. However, both directions are
544 * encrypted independently of each other.
545 */
546
547 void
packet_set_encryption_key(const u_char * key,u_int keylen,int number)548 packet_set_encryption_key(const u_char *key, u_int keylen, int number)
549 {
550 Cipher *cipher = cipher_by_number(number);
551
552 if (cipher == NULL)
553 fatal("packet_set_encryption_key: unknown cipher number %d", number);
554 if (keylen < 20)
555 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
556 if (keylen > SSH_SESSION_KEY_LENGTH)
557 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
558 memcpy(active_state->ssh1_key, key, keylen);
559 active_state->ssh1_keylen = keylen;
560 cipher_init(&active_state->send_context, cipher, key, keylen, NULL,
561 0, CIPHER_ENCRYPT);
562 cipher_init(&active_state->receive_context, cipher, key, keylen, NULL,
563 0, CIPHER_DECRYPT);
564 }
565
566 u_int
packet_get_encryption_key(u_char * key)567 packet_get_encryption_key(u_char *key)
568 {
569 if (key == NULL)
570 return (active_state->ssh1_keylen);
571 memcpy(key, active_state->ssh1_key, active_state->ssh1_keylen);
572 return (active_state->ssh1_keylen);
573 }
574
575 /* Start constructing a packet to send. */
576 void
packet_start(u_char type)577 packet_start(u_char type)
578 {
579 u_char buf[9];
580 int len;
581
582 DBG(debug("packet_start[%d]", type));
583 len = compat20 ? 6 : 9;
584 memset(buf, 0, len - 1);
585 buf[len - 1] = type;
586 buffer_clear(&active_state->outgoing_packet);
587 buffer_append(&active_state->outgoing_packet, buf, len);
588 }
589
590 /* Append payload. */
591 void
packet_put_char(int value)592 packet_put_char(int value)
593 {
594 char ch = value;
595
596 buffer_append(&active_state->outgoing_packet, &ch, 1);
597 }
598
599 void
packet_put_int(u_int value)600 packet_put_int(u_int value)
601 {
602 buffer_put_int(&active_state->outgoing_packet, value);
603 }
604
605 void
packet_put_int64(u_int64_t value)606 packet_put_int64(u_int64_t value)
607 {
608 buffer_put_int64(&active_state->outgoing_packet, value);
609 }
610
611 void
packet_put_string(const void * buf,u_int len)612 packet_put_string(const void *buf, u_int len)
613 {
614 buffer_put_string(&active_state->outgoing_packet, buf, len);
615 }
616
617 void
packet_put_cstring(const char * str)618 packet_put_cstring(const char *str)
619 {
620 buffer_put_cstring(&active_state->outgoing_packet, str);
621 }
622
623 void
packet_put_raw(const void * buf,u_int len)624 packet_put_raw(const void *buf, u_int len)
625 {
626 buffer_append(&active_state->outgoing_packet, buf, len);
627 }
628
629 void
packet_put_bignum(BIGNUM * value)630 packet_put_bignum(BIGNUM * value)
631 {
632 buffer_put_bignum(&active_state->outgoing_packet, value);
633 }
634
635 void
packet_put_bignum2(BIGNUM * value)636 packet_put_bignum2(BIGNUM * value)
637 {
638 buffer_put_bignum2(&active_state->outgoing_packet, value);
639 }
640
641 #ifdef OPENSSL_HAS_ECC
642 void
packet_put_ecpoint(const EC_GROUP * curve,const EC_POINT * point)643 packet_put_ecpoint(const EC_GROUP *curve, const EC_POINT *point)
644 {
645 buffer_put_ecpoint(&active_state->outgoing_packet, curve, point);
646 }
647 #endif
648
649 /*
650 * Finalizes and sends the packet. If the encryption key has been set,
651 * encrypts the packet before sending.
652 */
653
654 static void
packet_send1(void)655 packet_send1(void)
656 {
657 u_char buf[8], *cp;
658 int i, padding, len;
659 u_int checksum;
660 u_int32_t rnd = 0;
661
662 /*
663 * If using packet compression, compress the payload of the outgoing
664 * packet.
665 */
666 if (active_state->packet_compression) {
667 buffer_clear(&active_state->compression_buffer);
668 /* Skip padding. */
669 buffer_consume(&active_state->outgoing_packet, 8);
670 /* padding */
671 buffer_append(&active_state->compression_buffer,
672 "\0\0\0\0\0\0\0\0", 8);
673 buffer_compress(&active_state->outgoing_packet,
674 &active_state->compression_buffer);
675 buffer_clear(&active_state->outgoing_packet);
676 buffer_append(&active_state->outgoing_packet,
677 buffer_ptr(&active_state->compression_buffer),
678 buffer_len(&active_state->compression_buffer));
679 }
680 /* Compute packet length without padding (add checksum, remove padding). */
681 len = buffer_len(&active_state->outgoing_packet) + 4 - 8;
682
683 /* Insert padding. Initialized to zero in packet_start1() */
684 padding = 8 - len % 8;
685 if (!active_state->send_context.plaintext) {
686 cp = buffer_ptr(&active_state->outgoing_packet);
687 for (i = 0; i < padding; i++) {
688 if (i % 4 == 0)
689 rnd = arc4random();
690 cp[7 - i] = rnd & 0xff;
691 rnd >>= 8;
692 }
693 }
694 buffer_consume(&active_state->outgoing_packet, 8 - padding);
695
696 /* Add check bytes. */
697 checksum = ssh_crc32(buffer_ptr(&active_state->outgoing_packet),
698 buffer_len(&active_state->outgoing_packet));
699 put_u32(buf, checksum);
700 buffer_append(&active_state->outgoing_packet, buf, 4);
701
702 #ifdef PACKET_DEBUG
703 fprintf(stderr, "packet_send plain: ");
704 buffer_dump(&active_state->outgoing_packet);
705 #endif
706
707 /* Append to output. */
708 put_u32(buf, len);
709 buffer_append(&active_state->output, buf, 4);
710 cp = buffer_append_space(&active_state->output,
711 buffer_len(&active_state->outgoing_packet));
712 cipher_crypt(&active_state->send_context, cp,
713 buffer_ptr(&active_state->outgoing_packet),
714 buffer_len(&active_state->outgoing_packet));
715
716 #ifdef PACKET_DEBUG
717 fprintf(stderr, "encrypted: ");
718 buffer_dump(&active_state->output);
719 #endif
720 active_state->p_send.packets++;
721 active_state->p_send.bytes += len +
722 buffer_len(&active_state->outgoing_packet);
723 buffer_clear(&active_state->outgoing_packet);
724
725 /*
726 * Note that the packet is now only buffered in output. It won't be
727 * actually sent until packet_write_wait or packet_write_poll is
728 * called.
729 */
730 }
731
732 void
set_newkeys(int mode)733 set_newkeys(int mode)
734 {
735 Enc *enc;
736 Mac *mac;
737 Comp *comp;
738 CipherContext *cc;
739 u_int64_t *max_blocks;
740 int crypt_type;
741
742 debug2("set_newkeys: mode %d", mode);
743
744 if (mode == MODE_OUT) {
745 cc = &active_state->send_context;
746 crypt_type = CIPHER_ENCRYPT;
747 active_state->p_send.packets = active_state->p_send.blocks = 0;
748 max_blocks = &active_state->max_blocks_out;
749 } else {
750 cc = &active_state->receive_context;
751 crypt_type = CIPHER_DECRYPT;
752 active_state->p_read.packets = active_state->p_read.blocks = 0;
753 max_blocks = &active_state->max_blocks_in;
754 }
755 if (active_state->newkeys[mode] != NULL) {
756 debug("set_newkeys: rekeying");
757 cipher_cleanup(cc);
758 enc = &active_state->newkeys[mode]->enc;
759 mac = &active_state->newkeys[mode]->mac;
760 comp = &active_state->newkeys[mode]->comp;
761 mac_clear(mac);
762 xfree(enc->name);
763 xfree(enc->iv);
764 xfree(enc->key);
765 xfree(mac->name);
766 xfree(mac->key);
767 xfree(comp->name);
768 xfree(active_state->newkeys[mode]);
769 }
770 active_state->newkeys[mode] = kex_get_newkeys(mode);
771 if (active_state->newkeys[mode] == NULL)
772 fatal("newkeys: no keys for mode %d", mode);
773 enc = &active_state->newkeys[mode]->enc;
774 mac = &active_state->newkeys[mode]->mac;
775 comp = &active_state->newkeys[mode]->comp;
776 if (mac_init(mac) == 0)
777 mac->enabled = 1;
778 DBG(debug("cipher_init_context: %d", mode));
779 cipher_init(cc, enc->cipher, enc->key, enc->key_len,
780 enc->iv, enc->block_size, crypt_type);
781 /* Deleting the keys does not gain extra security */
782 /* memset(enc->iv, 0, enc->block_size);
783 memset(enc->key, 0, enc->key_len);
784 memset(mac->key, 0, mac->key_len); */
785 if ((comp->type == COMP_ZLIB ||
786 (comp->type == COMP_DELAYED &&
787 active_state->after_authentication)) && comp->enabled == 0) {
788 packet_init_compression();
789 if (mode == MODE_OUT)
790 buffer_compress_init_send(6);
791 else
792 buffer_compress_init_recv();
793 comp->enabled = 1;
794 }
795 /*
796 * The 2^(blocksize*2) limit is too expensive for 3DES,
797 * blowfish, etc, so enforce a 1GB limit for small blocksizes.
798 */
799 if (enc->block_size >= 16)
800 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
801 else
802 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
803 if (active_state->rekey_limit)
804 *max_blocks = MIN(*max_blocks,
805 active_state->rekey_limit / enc->block_size);
806 }
807
808 /*
809 * Delayed compression for SSH2 is enabled after authentication:
810 * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
811 * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
812 */
813 static void
packet_enable_delayed_compress(void)814 packet_enable_delayed_compress(void)
815 {
816 Comp *comp = NULL;
817 int mode;
818
819 /*
820 * Remember that we are past the authentication step, so rekeying
821 * with COMP_DELAYED will turn on compression immediately.
822 */
823 active_state->after_authentication = 1;
824 for (mode = 0; mode < MODE_MAX; mode++) {
825 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
826 if (active_state->newkeys[mode] == NULL)
827 continue;
828 comp = &active_state->newkeys[mode]->comp;
829 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
830 packet_init_compression();
831 if (mode == MODE_OUT)
832 buffer_compress_init_send(6);
833 else
834 buffer_compress_init_recv();
835 comp->enabled = 1;
836 }
837 }
838 }
839
840 /*
841 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
842 */
843 static void
packet_send2_wrapped(void)844 packet_send2_wrapped(void)
845 {
846 u_char type, *cp, *macbuf = NULL;
847 u_char padlen, pad;
848 u_int packet_length = 0;
849 u_int i, len;
850 u_int32_t rnd = 0;
851 Enc *enc = NULL;
852 Mac *mac = NULL;
853 Comp *comp = NULL;
854 int block_size;
855
856 if (active_state->newkeys[MODE_OUT] != NULL) {
857 enc = &active_state->newkeys[MODE_OUT]->enc;
858 mac = &active_state->newkeys[MODE_OUT]->mac;
859 comp = &active_state->newkeys[MODE_OUT]->comp;
860 }
861 block_size = enc ? enc->block_size : 8;
862
863 cp = buffer_ptr(&active_state->outgoing_packet);
864 type = cp[5];
865
866 #ifdef PACKET_DEBUG
867 fprintf(stderr, "plain: ");
868 buffer_dump(&active_state->outgoing_packet);
869 #endif
870
871 if (comp && comp->enabled) {
872 len = buffer_len(&active_state->outgoing_packet);
873 /* skip header, compress only payload */
874 buffer_consume(&active_state->outgoing_packet, 5);
875 buffer_clear(&active_state->compression_buffer);
876 buffer_compress(&active_state->outgoing_packet,
877 &active_state->compression_buffer);
878 buffer_clear(&active_state->outgoing_packet);
879 buffer_append(&active_state->outgoing_packet, "\0\0\0\0\0", 5);
880 buffer_append(&active_state->outgoing_packet,
881 buffer_ptr(&active_state->compression_buffer),
882 buffer_len(&active_state->compression_buffer));
883 DBG(debug("compression: raw %d compressed %d", len,
884 buffer_len(&active_state->outgoing_packet)));
885 }
886
887 /* sizeof (packet_len + pad_len + payload) */
888 len = buffer_len(&active_state->outgoing_packet);
889
890 /*
891 * calc size of padding, alloc space, get random data,
892 * minimum padding is 4 bytes
893 */
894 padlen = block_size - (len % block_size);
895 if (padlen < 4)
896 padlen += block_size;
897 if (active_state->extra_pad) {
898 /* will wrap if extra_pad+padlen > 255 */
899 active_state->extra_pad =
900 roundup(active_state->extra_pad, block_size);
901 pad = active_state->extra_pad -
902 ((len + padlen) % active_state->extra_pad);
903 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
904 pad, len, padlen, active_state->extra_pad);
905 padlen += pad;
906 active_state->extra_pad = 0;
907 }
908 cp = buffer_append_space(&active_state->outgoing_packet, padlen);
909 if (enc && !active_state->send_context.plaintext) {
910 /* random padding */
911 for (i = 0; i < padlen; i++) {
912 if (i % 4 == 0)
913 rnd = arc4random();
914 cp[i] = rnd & 0xff;
915 rnd >>= 8;
916 }
917 } else {
918 /* clear padding */
919 memset(cp, 0, padlen);
920 }
921 /* packet_length includes payload, padding and padding length field */
922 packet_length = buffer_len(&active_state->outgoing_packet) - 4;
923 cp = buffer_ptr(&active_state->outgoing_packet);
924 put_u32(cp, packet_length);
925 cp[4] = padlen;
926 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
927
928 /* compute MAC over seqnr and packet(length fields, payload, padding) */
929 if (mac && mac->enabled) {
930 macbuf = mac_compute(mac, active_state->p_send.seqnr,
931 buffer_ptr(&active_state->outgoing_packet),
932 buffer_len(&active_state->outgoing_packet));
933 DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
934 }
935 /* encrypt packet and append to output buffer. */
936 cp = buffer_append_space(&active_state->output,
937 buffer_len(&active_state->outgoing_packet));
938 cipher_crypt(&active_state->send_context, cp,
939 buffer_ptr(&active_state->outgoing_packet),
940 buffer_len(&active_state->outgoing_packet));
941 /* append unencrypted MAC */
942 if (mac && mac->enabled)
943 buffer_append(&active_state->output, macbuf, mac->mac_len);
944 #ifdef PACKET_DEBUG
945 fprintf(stderr, "encrypted: ");
946 buffer_dump(&active_state->output);
947 #endif
948 /* increment sequence number for outgoing packets */
949 if (++active_state->p_send.seqnr == 0)
950 logit("outgoing seqnr wraps around");
951 if (++active_state->p_send.packets == 0)
952 if (!(datafellows & SSH_BUG_NOREKEY))
953 fatal("XXX too many packets with same key");
954 active_state->p_send.blocks += (packet_length + 4) / block_size;
955 active_state->p_send.bytes += packet_length + 4;
956 buffer_clear(&active_state->outgoing_packet);
957
958 if (type == SSH2_MSG_NEWKEYS)
959 set_newkeys(MODE_OUT);
960 else if (type == SSH2_MSG_USERAUTH_SUCCESS && active_state->server_side)
961 packet_enable_delayed_compress();
962 }
963
964 static void
packet_send2(void)965 packet_send2(void)
966 {
967 struct packet *p;
968 u_char type, *cp;
969
970 cp = buffer_ptr(&active_state->outgoing_packet);
971 type = cp[5];
972
973 /* during rekeying we can only send key exchange messages */
974 if (active_state->rekeying) {
975 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
976 (type <= SSH2_MSG_TRANSPORT_MAX))) {
977 debug("enqueue packet: %u", type);
978 p = xmalloc(sizeof(*p));
979 p->type = type;
980 memcpy(&p->payload, &active_state->outgoing_packet,
981 sizeof(Buffer));
982 buffer_init(&active_state->outgoing_packet);
983 TAILQ_INSERT_TAIL(&active_state->outgoing, p, next);
984 return;
985 }
986 }
987
988 /* rekeying starts with sending KEXINIT */
989 if (type == SSH2_MSG_KEXINIT)
990 active_state->rekeying = 1;
991
992 packet_send2_wrapped();
993
994 /* after a NEWKEYS message we can send the complete queue */
995 if (type == SSH2_MSG_NEWKEYS) {
996 active_state->rekeying = 0;
997 while ((p = TAILQ_FIRST(&active_state->outgoing))) {
998 type = p->type;
999 debug("dequeue packet: %u", type);
1000 buffer_free(&active_state->outgoing_packet);
1001 memcpy(&active_state->outgoing_packet, &p->payload,
1002 sizeof(Buffer));
1003 TAILQ_REMOVE(&active_state->outgoing, p, next);
1004 xfree(p);
1005 packet_send2_wrapped();
1006 }
1007 }
1008 }
1009
1010 void
packet_send(void)1011 packet_send(void)
1012 {
1013 if (compat20)
1014 packet_send2();
1015 else
1016 packet_send1();
1017 DBG(debug("packet_send done"));
1018 }
1019
1020 /*
1021 * Waits until a packet has been received, and returns its type. Note that
1022 * no other data is processed until this returns, so this function should not
1023 * be used during the interactive session.
1024 */
1025
1026 int
packet_read_seqnr(u_int32_t * seqnr_p)1027 packet_read_seqnr(u_int32_t *seqnr_p)
1028 {
1029 int type, len, ret, ms_remain, cont;
1030 fd_set *setp;
1031 char buf[8192];
1032 struct timeval timeout, start, *timeoutp = NULL;
1033
1034 DBG(debug("packet_read()"));
1035
1036 setp = (fd_set *)xcalloc(howmany(active_state->connection_in + 1,
1037 NFDBITS), sizeof(fd_mask));
1038
1039 /* Since we are blocking, ensure that all written packets have been sent. */
1040 packet_write_wait();
1041
1042 /* Stay in the loop until we have received a complete packet. */
1043 for (;;) {
1044 /* Try to read a packet from the buffer. */
1045 type = packet_read_poll_seqnr(seqnr_p);
1046 if (!compat20 && (
1047 type == SSH_SMSG_SUCCESS
1048 || type == SSH_SMSG_FAILURE
1049 || type == SSH_CMSG_EOF
1050 || type == SSH_CMSG_EXIT_CONFIRMATION))
1051 packet_check_eom();
1052 /* If we got a packet, return it. */
1053 if (type != SSH_MSG_NONE) {
1054 xfree(setp);
1055 return type;
1056 }
1057 /*
1058 * Otherwise, wait for some data to arrive, add it to the
1059 * buffer, and try again.
1060 */
1061 memset(setp, 0, howmany(active_state->connection_in + 1,
1062 NFDBITS) * sizeof(fd_mask));
1063 FD_SET(active_state->connection_in, setp);
1064
1065 if (active_state->packet_timeout_ms > 0) {
1066 ms_remain = active_state->packet_timeout_ms;
1067 timeoutp = &timeout;
1068 }
1069 /* Wait for some data to arrive. */
1070 for (;;) {
1071 if (active_state->packet_timeout_ms != -1) {
1072 ms_to_timeval(&timeout, ms_remain);
1073 gettimeofday(&start, NULL);
1074 }
1075 if ((ret = select(active_state->connection_in + 1, setp,
1076 NULL, NULL, timeoutp)) >= 0)
1077 break;
1078 if (errno != EAGAIN && errno != EINTR &&
1079 errno != EWOULDBLOCK)
1080 break;
1081 if (active_state->packet_timeout_ms == -1)
1082 continue;
1083 ms_subtract_diff(&start, &ms_remain);
1084 if (ms_remain <= 0) {
1085 ret = 0;
1086 break;
1087 }
1088 }
1089 if (ret == 0) {
1090 logit("Connection to %.200s timed out while "
1091 "waiting to read", get_remote_ipaddr());
1092 cleanup_exit(255);
1093 }
1094 /* Read data from the socket. */
1095 do {
1096 cont = 0;
1097 len = roaming_read(active_state->connection_in, buf,
1098 sizeof(buf), &cont);
1099 } while (len == 0 && cont);
1100 if (len == 0) {
1101 logit("Connection closed by %.200s", get_remote_ipaddr());
1102 cleanup_exit(255);
1103 }
1104 if (len < 0)
1105 fatal("Read from socket failed: %.100s", strerror(errno));
1106 /* Append it to the buffer. */
1107 packet_process_incoming(buf, len);
1108 }
1109 /* NOTREACHED */
1110 }
1111
1112 int
packet_read(void)1113 packet_read(void)
1114 {
1115 return packet_read_seqnr(NULL);
1116 }
1117
1118 /*
1119 * Waits until a packet has been received, verifies that its type matches
1120 * that given, and gives a fatal error and exits if there is a mismatch.
1121 */
1122
1123 void
packet_read_expect(int expected_type)1124 packet_read_expect(int expected_type)
1125 {
1126 int type;
1127
1128 type = packet_read();
1129 if (type != expected_type)
1130 packet_disconnect("Protocol error: expected packet type %d, got %d",
1131 expected_type, type);
1132 }
1133
1134 /* Checks if a full packet is available in the data received so far via
1135 * packet_process_incoming. If so, reads the packet; otherwise returns
1136 * SSH_MSG_NONE. This does not wait for data from the connection.
1137 *
1138 * SSH_MSG_DISCONNECT is handled specially here. Also,
1139 * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1140 * to higher levels.
1141 */
1142
1143 static int
packet_read_poll1(void)1144 packet_read_poll1(void)
1145 {
1146 u_int len, padded_len;
1147 u_char *cp, type;
1148 u_int checksum, stored_checksum;
1149
1150 /* Check if input size is less than minimum packet size. */
1151 if (buffer_len(&active_state->input) < 4 + 8)
1152 return SSH_MSG_NONE;
1153 /* Get length of incoming packet. */
1154 cp = buffer_ptr(&active_state->input);
1155 len = get_u32(cp);
1156 if (len < 1 + 2 + 2 || len > 256 * 1024)
1157 packet_disconnect("Bad packet length %u.", len);
1158 padded_len = (len + 8) & ~7;
1159
1160 /* Check if the packet has been entirely received. */
1161 if (buffer_len(&active_state->input) < 4 + padded_len)
1162 return SSH_MSG_NONE;
1163
1164 /* The entire packet is in buffer. */
1165
1166 /* Consume packet length. */
1167 buffer_consume(&active_state->input, 4);
1168
1169 /*
1170 * Cryptographic attack detector for ssh
1171 * (C)1998 CORE-SDI, Buenos Aires Argentina
1172 * Ariel Futoransky(futo@core-sdi.com)
1173 */
1174 if (!active_state->receive_context.plaintext) {
1175 switch (detect_attack(buffer_ptr(&active_state->input),
1176 padded_len)) {
1177 case DEATTACK_DETECTED:
1178 packet_disconnect("crc32 compensation attack: "
1179 "network attack detected");
1180 case DEATTACK_DOS_DETECTED:
1181 packet_disconnect("deattack denial of "
1182 "service detected");
1183 }
1184 }
1185
1186 /* Decrypt data to incoming_packet. */
1187 buffer_clear(&active_state->incoming_packet);
1188 cp = buffer_append_space(&active_state->incoming_packet, padded_len);
1189 cipher_crypt(&active_state->receive_context, cp,
1190 buffer_ptr(&active_state->input), padded_len);
1191
1192 buffer_consume(&active_state->input, padded_len);
1193
1194 #ifdef PACKET_DEBUG
1195 fprintf(stderr, "read_poll plain: ");
1196 buffer_dump(&active_state->incoming_packet);
1197 #endif
1198
1199 /* Compute packet checksum. */
1200 checksum = ssh_crc32(buffer_ptr(&active_state->incoming_packet),
1201 buffer_len(&active_state->incoming_packet) - 4);
1202
1203 /* Skip padding. */
1204 buffer_consume(&active_state->incoming_packet, 8 - len % 8);
1205
1206 /* Test check bytes. */
1207 if (len != buffer_len(&active_state->incoming_packet))
1208 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1209 len, buffer_len(&active_state->incoming_packet));
1210
1211 cp = (u_char *)buffer_ptr(&active_state->incoming_packet) + len - 4;
1212 stored_checksum = get_u32(cp);
1213 if (checksum != stored_checksum)
1214 packet_disconnect("Corrupted check bytes on input.");
1215 buffer_consume_end(&active_state->incoming_packet, 4);
1216
1217 if (active_state->packet_compression) {
1218 buffer_clear(&active_state->compression_buffer);
1219 buffer_uncompress(&active_state->incoming_packet,
1220 &active_state->compression_buffer);
1221 buffer_clear(&active_state->incoming_packet);
1222 buffer_append(&active_state->incoming_packet,
1223 buffer_ptr(&active_state->compression_buffer),
1224 buffer_len(&active_state->compression_buffer));
1225 }
1226 active_state->p_read.packets++;
1227 active_state->p_read.bytes += padded_len + 4;
1228 type = buffer_get_char(&active_state->incoming_packet);
1229 if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1230 packet_disconnect("Invalid ssh1 packet type: %d", type);
1231 return type;
1232 }
1233
1234 static int
packet_read_poll2(u_int32_t * seqnr_p)1235 packet_read_poll2(u_int32_t *seqnr_p)
1236 {
1237 u_int padlen, need;
1238 u_char *macbuf, *cp, type;
1239 u_int maclen, block_size;
1240 Enc *enc = NULL;
1241 Mac *mac = NULL;
1242 Comp *comp = NULL;
1243
1244 if (active_state->packet_discard)
1245 return SSH_MSG_NONE;
1246
1247 if (active_state->newkeys[MODE_IN] != NULL) {
1248 enc = &active_state->newkeys[MODE_IN]->enc;
1249 mac = &active_state->newkeys[MODE_IN]->mac;
1250 comp = &active_state->newkeys[MODE_IN]->comp;
1251 }
1252 maclen = mac && mac->enabled ? mac->mac_len : 0;
1253 block_size = enc ? enc->block_size : 8;
1254
1255 if (active_state->packlen == 0) {
1256 /*
1257 * check if input size is less than the cipher block size,
1258 * decrypt first block and extract length of incoming packet
1259 */
1260 if (buffer_len(&active_state->input) < block_size)
1261 return SSH_MSG_NONE;
1262 buffer_clear(&active_state->incoming_packet);
1263 cp = buffer_append_space(&active_state->incoming_packet,
1264 block_size);
1265 cipher_crypt(&active_state->receive_context, cp,
1266 buffer_ptr(&active_state->input), block_size);
1267 cp = buffer_ptr(&active_state->incoming_packet);
1268 active_state->packlen = get_u32(cp);
1269 if (active_state->packlen < 1 + 4 ||
1270 active_state->packlen > PACKET_MAX_SIZE) {
1271 #ifdef PACKET_DEBUG
1272 buffer_dump(&active_state->incoming_packet);
1273 #endif
1274 logit("Bad packet length %u.", active_state->packlen);
1275 packet_start_discard(enc, mac, active_state->packlen,
1276 PACKET_MAX_SIZE);
1277 return SSH_MSG_NONE;
1278 }
1279 DBG(debug("input: packet len %u", active_state->packlen+4));
1280 buffer_consume(&active_state->input, block_size);
1281 }
1282 /* we have a partial packet of block_size bytes */
1283 need = 4 + active_state->packlen - block_size;
1284 DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1285 need, maclen));
1286 if (need % block_size != 0) {
1287 logit("padding error: need %d block %d mod %d",
1288 need, block_size, need % block_size);
1289 packet_start_discard(enc, mac, active_state->packlen,
1290 PACKET_MAX_SIZE - block_size);
1291 return SSH_MSG_NONE;
1292 }
1293 /*
1294 * check if the entire packet has been received and
1295 * decrypt into incoming_packet
1296 */
1297 if (buffer_len(&active_state->input) < need + maclen)
1298 return SSH_MSG_NONE;
1299 #ifdef PACKET_DEBUG
1300 fprintf(stderr, "read_poll enc/full: ");
1301 buffer_dump(&active_state->input);
1302 #endif
1303 cp = buffer_append_space(&active_state->incoming_packet, need);
1304 cipher_crypt(&active_state->receive_context, cp,
1305 buffer_ptr(&active_state->input), need);
1306 buffer_consume(&active_state->input, need);
1307 /*
1308 * compute MAC over seqnr and packet,
1309 * increment sequence number for incoming packet
1310 */
1311 if (mac && mac->enabled) {
1312 macbuf = mac_compute(mac, active_state->p_read.seqnr,
1313 buffer_ptr(&active_state->incoming_packet),
1314 buffer_len(&active_state->incoming_packet));
1315 if (timingsafe_bcmp(macbuf, buffer_ptr(&active_state->input),
1316 mac->mac_len) != 0) {
1317 logit("Corrupted MAC on input.");
1318 if (need > PACKET_MAX_SIZE)
1319 fatal("internal error need %d", need);
1320 packet_start_discard(enc, mac, active_state->packlen,
1321 PACKET_MAX_SIZE - need);
1322 return SSH_MSG_NONE;
1323 }
1324
1325 DBG(debug("MAC #%d ok", active_state->p_read.seqnr));
1326 buffer_consume(&active_state->input, mac->mac_len);
1327 }
1328 /* XXX now it's safe to use fatal/packet_disconnect */
1329 if (seqnr_p != NULL)
1330 *seqnr_p = active_state->p_read.seqnr;
1331 if (++active_state->p_read.seqnr == 0)
1332 logit("incoming seqnr wraps around");
1333 if (++active_state->p_read.packets == 0)
1334 if (!(datafellows & SSH_BUG_NOREKEY))
1335 fatal("XXX too many packets with same key");
1336 active_state->p_read.blocks += (active_state->packlen + 4) / block_size;
1337 active_state->p_read.bytes += active_state->packlen + 4;
1338
1339 /* get padlen */
1340 cp = buffer_ptr(&active_state->incoming_packet);
1341 padlen = cp[4];
1342 DBG(debug("input: padlen %d", padlen));
1343 if (padlen < 4)
1344 packet_disconnect("Corrupted padlen %d on input.", padlen);
1345
1346 /* skip packet size + padlen, discard padding */
1347 buffer_consume(&active_state->incoming_packet, 4 + 1);
1348 buffer_consume_end(&active_state->incoming_packet, padlen);
1349
1350 DBG(debug("input: len before de-compress %d",
1351 buffer_len(&active_state->incoming_packet)));
1352 if (comp && comp->enabled) {
1353 buffer_clear(&active_state->compression_buffer);
1354 buffer_uncompress(&active_state->incoming_packet,
1355 &active_state->compression_buffer);
1356 buffer_clear(&active_state->incoming_packet);
1357 buffer_append(&active_state->incoming_packet,
1358 buffer_ptr(&active_state->compression_buffer),
1359 buffer_len(&active_state->compression_buffer));
1360 DBG(debug("input: len after de-compress %d",
1361 buffer_len(&active_state->incoming_packet)));
1362 }
1363 /*
1364 * get packet type, implies consume.
1365 * return length of payload (without type field)
1366 */
1367 type = buffer_get_char(&active_state->incoming_packet);
1368 if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1369 packet_disconnect("Invalid ssh2 packet type: %d", type);
1370 if (type == SSH2_MSG_NEWKEYS)
1371 set_newkeys(MODE_IN);
1372 else if (type == SSH2_MSG_USERAUTH_SUCCESS &&
1373 !active_state->server_side)
1374 packet_enable_delayed_compress();
1375 #ifdef PACKET_DEBUG
1376 fprintf(stderr, "read/plain[%d]:\r\n", type);
1377 buffer_dump(&active_state->incoming_packet);
1378 #endif
1379 /* reset for next packet */
1380 active_state->packlen = 0;
1381 return type;
1382 }
1383
1384 int
packet_read_poll_seqnr(u_int32_t * seqnr_p)1385 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1386 {
1387 u_int reason, seqnr;
1388 u_char type;
1389 char *msg;
1390
1391 for (;;) {
1392 if (compat20) {
1393 type = packet_read_poll2(seqnr_p);
1394 if (type) {
1395 active_state->keep_alive_timeouts = 0;
1396 DBG(debug("received packet type %d", type));
1397 }
1398 switch (type) {
1399 case SSH2_MSG_IGNORE:
1400 debug3("Received SSH2_MSG_IGNORE");
1401 break;
1402 case SSH2_MSG_DEBUG:
1403 packet_get_char();
1404 msg = packet_get_string(NULL);
1405 debug("Remote: %.900s", msg);
1406 xfree(msg);
1407 msg = packet_get_string(NULL);
1408 xfree(msg);
1409 break;
1410 case SSH2_MSG_DISCONNECT:
1411 reason = packet_get_int();
1412 msg = packet_get_string(NULL);
1413 logit("Received disconnect from %s: %u: %.400s",
1414 get_remote_ipaddr(), reason, msg);
1415 xfree(msg);
1416 cleanup_exit(255);
1417 break;
1418 case SSH2_MSG_UNIMPLEMENTED:
1419 seqnr = packet_get_int();
1420 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1421 seqnr);
1422 break;
1423 default:
1424 return type;
1425 }
1426 } else {
1427 type = packet_read_poll1();
1428 switch (type) {
1429 case SSH_MSG_IGNORE:
1430 break;
1431 case SSH_MSG_DEBUG:
1432 msg = packet_get_string(NULL);
1433 debug("Remote: %.900s", msg);
1434 xfree(msg);
1435 break;
1436 case SSH_MSG_DISCONNECT:
1437 msg = packet_get_string(NULL);
1438 logit("Received disconnect from %s: %.400s",
1439 get_remote_ipaddr(), msg);
1440 cleanup_exit(255);
1441 break;
1442 default:
1443 if (type)
1444 DBG(debug("received packet type %d", type));
1445 return type;
1446 }
1447 }
1448 }
1449 }
1450
1451 int
packet_read_poll(void)1452 packet_read_poll(void)
1453 {
1454 return packet_read_poll_seqnr(NULL);
1455 }
1456
1457 /*
1458 * Buffers the given amount of input characters. This is intended to be used
1459 * together with packet_read_poll.
1460 */
1461
1462 void
packet_process_incoming(const char * buf,u_int len)1463 packet_process_incoming(const char *buf, u_int len)
1464 {
1465 if (active_state->packet_discard) {
1466 active_state->keep_alive_timeouts = 0; /* ?? */
1467 if (len >= active_state->packet_discard)
1468 packet_stop_discard();
1469 active_state->packet_discard -= len;
1470 return;
1471 }
1472 buffer_append(&active_state->input, buf, len);
1473 }
1474
1475 /* Returns a character from the packet. */
1476
1477 u_int
packet_get_char(void)1478 packet_get_char(void)
1479 {
1480 char ch;
1481
1482 buffer_get(&active_state->incoming_packet, &ch, 1);
1483 return (u_char) ch;
1484 }
1485
1486 /* Returns an integer from the packet data. */
1487
1488 u_int
packet_get_int(void)1489 packet_get_int(void)
1490 {
1491 return buffer_get_int(&active_state->incoming_packet);
1492 }
1493
1494 /* Returns an 64 bit integer from the packet data. */
1495
1496 u_int64_t
packet_get_int64(void)1497 packet_get_int64(void)
1498 {
1499 return buffer_get_int64(&active_state->incoming_packet);
1500 }
1501
1502 /*
1503 * Returns an arbitrary precision integer from the packet data. The integer
1504 * must have been initialized before this call.
1505 */
1506
1507 void
packet_get_bignum(BIGNUM * value)1508 packet_get_bignum(BIGNUM * value)
1509 {
1510 buffer_get_bignum(&active_state->incoming_packet, value);
1511 }
1512
1513 void
packet_get_bignum2(BIGNUM * value)1514 packet_get_bignum2(BIGNUM * value)
1515 {
1516 buffer_get_bignum2(&active_state->incoming_packet, value);
1517 }
1518
1519 #ifdef OPENSSL_HAS_ECC
1520 void
packet_get_ecpoint(const EC_GROUP * curve,EC_POINT * point)1521 packet_get_ecpoint(const EC_GROUP *curve, EC_POINT *point)
1522 {
1523 buffer_get_ecpoint(&active_state->incoming_packet, curve, point);
1524 }
1525 #endif
1526
1527 void *
packet_get_raw(u_int * length_ptr)1528 packet_get_raw(u_int *length_ptr)
1529 {
1530 u_int bytes = buffer_len(&active_state->incoming_packet);
1531
1532 if (length_ptr != NULL)
1533 *length_ptr = bytes;
1534 return buffer_ptr(&active_state->incoming_packet);
1535 }
1536
1537 int
packet_remaining(void)1538 packet_remaining(void)
1539 {
1540 return buffer_len(&active_state->incoming_packet);
1541 }
1542
1543 /*
1544 * Returns a string from the packet data. The string is allocated using
1545 * xmalloc; it is the responsibility of the calling program to free it when
1546 * no longer needed. The length_ptr argument may be NULL, or point to an
1547 * integer into which the length of the string is stored.
1548 */
1549
1550 void *
packet_get_string(u_int * length_ptr)1551 packet_get_string(u_int *length_ptr)
1552 {
1553 return buffer_get_string(&active_state->incoming_packet, length_ptr);
1554 }
1555
1556 void *
packet_get_string_ptr(u_int * length_ptr)1557 packet_get_string_ptr(u_int *length_ptr)
1558 {
1559 return buffer_get_string_ptr(&active_state->incoming_packet, length_ptr);
1560 }
1561
1562 /* Ensures the returned string has no embedded \0 characters in it. */
1563 char *
packet_get_cstring(u_int * length_ptr)1564 packet_get_cstring(u_int *length_ptr)
1565 {
1566 return buffer_get_cstring(&active_state->incoming_packet, length_ptr);
1567 }
1568
1569 /*
1570 * Sends a diagnostic message from the server to the client. This message
1571 * can be sent at any time (but not while constructing another message). The
1572 * message is printed immediately, but only if the client is being executed
1573 * in verbose mode. These messages are primarily intended to ease debugging
1574 * authentication problems. The length of the formatted message must not
1575 * exceed 1024 bytes. This will automatically call packet_write_wait.
1576 */
1577
1578 void
packet_send_debug(const char * fmt,...)1579 packet_send_debug(const char *fmt,...)
1580 {
1581 char buf[1024];
1582 va_list args;
1583
1584 if (compat20 && (datafellows & SSH_BUG_DEBUG))
1585 return;
1586
1587 va_start(args, fmt);
1588 vsnprintf(buf, sizeof(buf), fmt, args);
1589 va_end(args);
1590
1591 if (compat20) {
1592 packet_start(SSH2_MSG_DEBUG);
1593 packet_put_char(0); /* bool: always display */
1594 packet_put_cstring(buf);
1595 packet_put_cstring("");
1596 } else {
1597 packet_start(SSH_MSG_DEBUG);
1598 packet_put_cstring(buf);
1599 }
1600 packet_send();
1601 packet_write_wait();
1602 }
1603
1604 /*
1605 * Logs the error plus constructs and sends a disconnect packet, closes the
1606 * connection, and exits. This function never returns. The error message
1607 * should not contain a newline. The length of the formatted message must
1608 * not exceed 1024 bytes.
1609 */
1610
1611 void
packet_disconnect(const char * fmt,...)1612 packet_disconnect(const char *fmt,...)
1613 {
1614 char buf[1024];
1615 va_list args;
1616 static int disconnecting = 0;
1617
1618 if (disconnecting) /* Guard against recursive invocations. */
1619 fatal("packet_disconnect called recursively.");
1620 disconnecting = 1;
1621
1622 /*
1623 * Format the message. Note that the caller must make sure the
1624 * message is of limited size.
1625 */
1626 va_start(args, fmt);
1627 vsnprintf(buf, sizeof(buf), fmt, args);
1628 va_end(args);
1629
1630 /* Display the error locally */
1631 logit("Disconnecting: %.100s", buf);
1632
1633 /* Send the disconnect message to the other side, and wait for it to get sent. */
1634 if (compat20) {
1635 packet_start(SSH2_MSG_DISCONNECT);
1636 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1637 packet_put_cstring(buf);
1638 packet_put_cstring("");
1639 } else {
1640 packet_start(SSH_MSG_DISCONNECT);
1641 packet_put_cstring(buf);
1642 }
1643 packet_send();
1644 packet_write_wait();
1645
1646 /* Stop listening for connections. */
1647 channel_close_all();
1648
1649 /* Close the connection. */
1650 packet_close();
1651 cleanup_exit(255);
1652 }
1653
1654 /* Checks if there is any buffered output, and tries to write some of the output. */
1655
1656 void
packet_write_poll(void)1657 packet_write_poll(void)
1658 {
1659 int len = buffer_len(&active_state->output);
1660 int cont;
1661
1662 if (len > 0) {
1663 cont = 0;
1664 len = roaming_write(active_state->connection_out,
1665 buffer_ptr(&active_state->output), len, &cont);
1666 if (len == -1) {
1667 if (errno == EINTR || errno == EAGAIN ||
1668 errno == EWOULDBLOCK)
1669 return;
1670 fatal("Write failed: %.100s", strerror(errno));
1671 }
1672 if (len == 0 && !cont)
1673 fatal("Write connection closed");
1674 buffer_consume(&active_state->output, len);
1675 }
1676 }
1677
1678 /*
1679 * Calls packet_write_poll repeatedly until all pending output data has been
1680 * written.
1681 */
1682
1683 void
packet_write_wait(void)1684 packet_write_wait(void)
1685 {
1686 fd_set *setp;
1687 int ret, ms_remain;
1688 struct timeval start, timeout, *timeoutp = NULL;
1689
1690 setp = (fd_set *)xcalloc(howmany(active_state->connection_out + 1,
1691 NFDBITS), sizeof(fd_mask));
1692 packet_write_poll();
1693 while (packet_have_data_to_write()) {
1694 memset(setp, 0, howmany(active_state->connection_out + 1,
1695 NFDBITS) * sizeof(fd_mask));
1696 FD_SET(active_state->connection_out, setp);
1697
1698 if (active_state->packet_timeout_ms > 0) {
1699 ms_remain = active_state->packet_timeout_ms;
1700 timeoutp = &timeout;
1701 }
1702 for (;;) {
1703 if (active_state->packet_timeout_ms != -1) {
1704 ms_to_timeval(&timeout, ms_remain);
1705 gettimeofday(&start, NULL);
1706 }
1707 if ((ret = select(active_state->connection_out + 1,
1708 NULL, setp, NULL, timeoutp)) >= 0)
1709 break;
1710 if (errno != EAGAIN && errno != EINTR &&
1711 errno != EWOULDBLOCK)
1712 break;
1713 if (active_state->packet_timeout_ms == -1)
1714 continue;
1715 ms_subtract_diff(&start, &ms_remain);
1716 if (ms_remain <= 0) {
1717 ret = 0;
1718 break;
1719 }
1720 }
1721 if (ret == 0) {
1722 logit("Connection to %.200s timed out while "
1723 "waiting to write", get_remote_ipaddr());
1724 cleanup_exit(255);
1725 }
1726 packet_write_poll();
1727 }
1728 xfree(setp);
1729 }
1730
1731 /* Returns true if there is buffered data to write to the connection. */
1732
1733 int
packet_have_data_to_write(void)1734 packet_have_data_to_write(void)
1735 {
1736 return buffer_len(&active_state->output) != 0;
1737 }
1738
1739 /* Returns true if there is not too much data to write to the connection. */
1740
1741 int
packet_not_very_much_data_to_write(void)1742 packet_not_very_much_data_to_write(void)
1743 {
1744 if (active_state->interactive_mode)
1745 return buffer_len(&active_state->output) < 16384;
1746 else
1747 return buffer_len(&active_state->output) < 128 * 1024;
1748 }
1749
1750 static void
packet_set_tos(int tos)1751 packet_set_tos(int tos)
1752 {
1753 #ifndef IP_TOS_IS_BROKEN
1754 if (!packet_connection_is_on_socket())
1755 return;
1756 switch (packet_connection_af()) {
1757 # ifdef IP_TOS
1758 case AF_INET:
1759 debug3("%s: set IP_TOS 0x%02x", __func__, tos);
1760 if (setsockopt(active_state->connection_in,
1761 IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) < 0)
1762 error("setsockopt IP_TOS %d: %.100s:",
1763 tos, strerror(errno));
1764 break;
1765 # endif /* IP_TOS */
1766 # ifdef IPV6_TCLASS
1767 case AF_INET6:
1768 debug3("%s: set IPV6_TCLASS 0x%02x", __func__, tos);
1769 if (setsockopt(active_state->connection_in,
1770 IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos)) < 0)
1771 error("setsockopt IPV6_TCLASS %d: %.100s:",
1772 tos, strerror(errno));
1773 break;
1774 # endif /* IPV6_TCLASS */
1775 }
1776 #endif /* IP_TOS_IS_BROKEN */
1777 }
1778
1779 /* Informs that the current session is interactive. Sets IP flags for that. */
1780
1781 void
packet_set_interactive(int interactive,int qos_interactive,int qos_bulk)1782 packet_set_interactive(int interactive, int qos_interactive, int qos_bulk)
1783 {
1784 if (active_state->set_interactive_called)
1785 return;
1786 active_state->set_interactive_called = 1;
1787
1788 /* Record that we are in interactive mode. */
1789 active_state->interactive_mode = interactive;
1790
1791 /* Only set socket options if using a socket. */
1792 if (!packet_connection_is_on_socket())
1793 return;
1794 set_nodelay(active_state->connection_in);
1795 packet_set_tos(interactive ? qos_interactive : qos_bulk);
1796 }
1797
1798 /* Returns true if the current connection is interactive. */
1799
1800 int
packet_is_interactive(void)1801 packet_is_interactive(void)
1802 {
1803 return active_state->interactive_mode;
1804 }
1805
1806 int
packet_set_maxsize(u_int s)1807 packet_set_maxsize(u_int s)
1808 {
1809 if (active_state->set_maxsize_called) {
1810 logit("packet_set_maxsize: called twice: old %d new %d",
1811 active_state->max_packet_size, s);
1812 return -1;
1813 }
1814 if (s < 4 * 1024 || s > 1024 * 1024) {
1815 logit("packet_set_maxsize: bad size %d", s);
1816 return -1;
1817 }
1818 active_state->set_maxsize_called = 1;
1819 debug("packet_set_maxsize: setting to %d", s);
1820 active_state->max_packet_size = s;
1821 return s;
1822 }
1823
1824 int
packet_inc_alive_timeouts(void)1825 packet_inc_alive_timeouts(void)
1826 {
1827 return ++active_state->keep_alive_timeouts;
1828 }
1829
1830 void
packet_set_alive_timeouts(int ka)1831 packet_set_alive_timeouts(int ka)
1832 {
1833 active_state->keep_alive_timeouts = ka;
1834 }
1835
1836 u_int
packet_get_maxsize(void)1837 packet_get_maxsize(void)
1838 {
1839 return active_state->max_packet_size;
1840 }
1841
1842 /* roundup current message to pad bytes */
1843 void
packet_add_padding(u_char pad)1844 packet_add_padding(u_char pad)
1845 {
1846 active_state->extra_pad = pad;
1847 }
1848
1849 /*
1850 * 9.2. Ignored Data Message
1851 *
1852 * byte SSH_MSG_IGNORE
1853 * string data
1854 *
1855 * All implementations MUST understand (and ignore) this message at any
1856 * time (after receiving the protocol version). No implementation is
1857 * required to send them. This message can be used as an additional
1858 * protection measure against advanced traffic analysis techniques.
1859 */
1860 void
packet_send_ignore(int nbytes)1861 packet_send_ignore(int nbytes)
1862 {
1863 u_int32_t rnd = 0;
1864 int i;
1865
1866 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1867 packet_put_int(nbytes);
1868 for (i = 0; i < nbytes; i++) {
1869 if (i % 4 == 0)
1870 rnd = arc4random();
1871 packet_put_char((u_char)rnd & 0xff);
1872 rnd >>= 8;
1873 }
1874 }
1875
1876 #define MAX_PACKETS (1U<<31)
1877 int
packet_need_rekeying(void)1878 packet_need_rekeying(void)
1879 {
1880 if (datafellows & SSH_BUG_NOREKEY)
1881 return 0;
1882 return
1883 (active_state->p_send.packets > MAX_PACKETS) ||
1884 (active_state->p_read.packets > MAX_PACKETS) ||
1885 (active_state->max_blocks_out &&
1886 (active_state->p_send.blocks > active_state->max_blocks_out)) ||
1887 (active_state->max_blocks_in &&
1888 (active_state->p_read.blocks > active_state->max_blocks_in));
1889 }
1890
1891 void
packet_set_rekey_limit(u_int32_t bytes)1892 packet_set_rekey_limit(u_int32_t bytes)
1893 {
1894 active_state->rekey_limit = bytes;
1895 }
1896
1897 void
packet_set_server(void)1898 packet_set_server(void)
1899 {
1900 active_state->server_side = 1;
1901 }
1902
1903 void
packet_set_authenticated(void)1904 packet_set_authenticated(void)
1905 {
1906 active_state->after_authentication = 1;
1907 }
1908
1909 void *
packet_get_input(void)1910 packet_get_input(void)
1911 {
1912 return (void *)&active_state->input;
1913 }
1914
1915 void *
packet_get_output(void)1916 packet_get_output(void)
1917 {
1918 return (void *)&active_state->output;
1919 }
1920
1921 void *
packet_get_newkeys(int mode)1922 packet_get_newkeys(int mode)
1923 {
1924 return (void *)active_state->newkeys[mode];
1925 }
1926
1927 /*
1928 * Save the state for the real connection, and use a separate state when
1929 * resuming a suspended connection.
1930 */
1931 void
packet_backup_state(void)1932 packet_backup_state(void)
1933 {
1934 struct session_state *tmp;
1935
1936 close(active_state->connection_in);
1937 active_state->connection_in = -1;
1938 close(active_state->connection_out);
1939 active_state->connection_out = -1;
1940 if (backup_state)
1941 tmp = backup_state;
1942 else
1943 tmp = alloc_session_state();
1944 backup_state = active_state;
1945 active_state = tmp;
1946 }
1947
1948 /*
1949 * Swap in the old state when resuming a connecion.
1950 */
1951 void
packet_restore_state(void)1952 packet_restore_state(void)
1953 {
1954 struct session_state *tmp;
1955 void *buf;
1956 u_int len;
1957
1958 tmp = backup_state;
1959 backup_state = active_state;
1960 active_state = tmp;
1961 active_state->connection_in = backup_state->connection_in;
1962 backup_state->connection_in = -1;
1963 active_state->connection_out = backup_state->connection_out;
1964 backup_state->connection_out = -1;
1965 len = buffer_len(&backup_state->input);
1966 if (len > 0) {
1967 buf = buffer_ptr(&backup_state->input);
1968 buffer_append(&active_state->input, buf, len);
1969 buffer_clear(&backup_state->input);
1970 add_recv_bytes(len);
1971 }
1972 }
1973