Annotation of src/usr.bin/ssh/packet.c, Revision 1.160
1.160 ! markus 1: /* $OpenBSD: packet.c,v 1.159 2009/01/26 09:58:15 markus Exp $ */
1.1 deraadt 2: /*
1.15 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
1.35 deraadt 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.
1.29 markus 8: *
1.35 deraadt 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".
1.29 markus 14: *
1.25 markus 15: *
16: * SSH2 packet format added by Markus Friedl.
1.69 markus 17: * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
1.25 markus 18: *
1.35 deraadt 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.
1.15 deraadt 38: */
1.1 deraadt 39:
1.142 deraadt 40: #include <sys/types.h>
1.105 markus 41: #include <sys/queue.h>
1.132 stevesk 42: #include <sys/socket.h>
1.138 stevesk 43: #include <sys/time.h>
1.139 stevesk 44: #include <sys/param.h>
1.121 stevesk 45:
46: #include <netinet/in_systm.h>
1.132 stevesk 47: #include <netinet/in.h>
1.121 stevesk 48: #include <netinet/ip.h>
1.134 stevesk 49:
1.135 stevesk 50: #include <errno.h>
1.134 stevesk 51: #include <stdarg.h>
1.141 stevesk 52: #include <stdio.h>
1.140 stevesk 53: #include <stdlib.h>
1.137 stevesk 54: #include <string.h>
1.136 stevesk 55: #include <unistd.h>
1.142 deraadt 56: #include <signal.h>
1.1 deraadt 57:
58: #include "xmalloc.h"
59: #include "buffer.h"
60: #include "packet.h"
61: #include "crc32.h"
62: #include "compress.h"
1.9 dugsong 63: #include "deattack.h"
1.64 markus 64: #include "channels.h"
1.25 markus 65: #include "compat.h"
1.45 markus 66: #include "ssh1.h"
1.25 markus 67: #include "ssh2.h"
1.37 markus 68: #include "cipher.h"
1.142 deraadt 69: #include "key.h"
1.25 markus 70: #include "kex.h"
1.50 markus 71: #include "mac.h"
1.46 markus 72: #include "log.h"
73: #include "canohost.h"
1.87 stevesk 74: #include "misc.h"
1.95 markus 75: #include "ssh.h"
1.25 markus 76:
77: #ifdef PACKET_DEBUG
78: #define DBG(x) x
79: #else
80: #define DBG(x)
81: #endif
82:
1.159 markus 83: #define PACKET_MAX_SIZE (256 * 1024)
84:
1.16 markus 85: /*
86: * This variable contains the file descriptors used for communicating with
87: * the other side. connection_in is used for reading; connection_out for
88: * writing. These can be the same descriptor, in which case it is assumed to
89: * be a socket.
90: */
1.1 deraadt 91: static int connection_in = -1;
92: static int connection_out = -1;
93:
94: /* Protocol flags for the remote side. */
1.40 markus 95: static u_int remote_protocol_flags = 0;
1.1 deraadt 96:
97: /* Encryption context for receiving data. This is only used for decryption. */
98: static CipherContext receive_context;
1.14 markus 99:
100: /* Encryption context for sending data. This is only used for encryption. */
1.1 deraadt 101: static CipherContext send_context;
102:
103: /* Buffer for raw input data from the socket. */
1.91 markus 104: Buffer input;
1.1 deraadt 105:
106: /* Buffer for raw output data going to the socket. */
1.91 markus 107: Buffer output;
1.1 deraadt 108:
109: /* Buffer for the partial outgoing packet being constructed. */
110: static Buffer outgoing_packet;
111:
112: /* Buffer for the incoming packet currently being processed. */
113: static Buffer incoming_packet;
114:
115: /* Scratch buffer for packet compression/decompression. */
116: static Buffer compression_buffer;
1.60 markus 117: static int compression_buffer_ready = 0;
1.1 deraadt 118:
119: /* Flag indicating whether packet compression/decompression is enabled. */
120: static int packet_compression = 0;
121:
1.12 markus 122: /* default maximum packet size */
1.108 markus 123: u_int max_packet_size = 32768;
1.12 markus 124:
1.1 deraadt 125: /* Flag indicating whether this module has been initialized. */
126: static int initialized = 0;
127:
128: /* Set to true if the connection is interactive. */
129: static int interactive_mode = 0;
130:
1.118 markus 131: /* Set to true if we are the server side. */
132: static int server_side = 0;
133:
134: /* Set to true if we are authenticated. */
135: static int after_authentication = 0;
136:
1.151 dtucker 137: int keep_alive_timeouts = 0;
138:
1.154 dtucker 139: /* Set to the maximum time that we will wait to send or receive a packet */
140: static int packet_timeout_ms = -1;
141:
1.25 markus 142: /* Session key information for Encryption and MAC */
1.57 markus 143: Newkeys *newkeys[MODE_MAX];
1.105 markus 144: static struct packet_state {
145: u_int32_t seqnr;
146: u_int32_t packets;
147: u_int64_t blocks;
1.157 markus 148: u_int64_t bytes;
1.105 markus 149: } p_read, p_send;
150:
151: static u_int64_t max_blocks_in, max_blocks_out;
152: static u_int32_t rekey_limit;
1.25 markus 153:
1.95 markus 154: /* Session key for protocol v1 */
155: static u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
156: static u_int ssh1_keylen;
157:
1.71 markus 158: /* roundup current message to extra_pad bytes */
159: static u_char extra_pad = 0;
160:
1.159 markus 161: /* XXX discard incoming data after MAC error */
162: static u_int packet_discard = 0;
163: static Mac *packet_discard_mac = NULL;
164:
1.105 markus 165: struct packet {
166: TAILQ_ENTRY(packet) next;
167: u_char type;
168: Buffer payload;
169: };
170: TAILQ_HEAD(, packet) outgoing;
171:
1.16 markus 172: /*
173: * Sets the descriptors used for communication. Disables encryption until
174: * packet_set_encryption_key is called.
175: */
1.2 provos 176: void
177: packet_set_connection(int fd_in, int fd_out)
1.1 deraadt 178: {
1.37 markus 179: Cipher *none = cipher_by_name("none");
1.97 deraadt 180:
1.37 markus 181: if (none == NULL)
182: fatal("packet_set_connection: cannot load cipher 'none'");
1.14 markus 183: connection_in = fd_in;
184: connection_out = fd_out;
1.113 deraadt 185: cipher_init(&send_context, none, (const u_char *)"",
186: 0, NULL, 0, CIPHER_ENCRYPT);
187: cipher_init(&receive_context, none, (const u_char *)"",
188: 0, NULL, 0, CIPHER_DECRYPT);
1.62 markus 189: newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
1.14 markus 190: if (!initialized) {
191: initialized = 1;
192: buffer_init(&input);
193: buffer_init(&output);
194: buffer_init(&outgoing_packet);
195: buffer_init(&incoming_packet);
1.105 markus 196: TAILQ_INIT(&outgoing);
1.157 markus 197: p_send.packets = p_read.packets = 0;
1.14 markus 198: }
1.1 deraadt 199: }
200:
1.154 dtucker 201: void
202: packet_set_timeout(int timeout, int count)
203: {
204: if (timeout == 0 || count == 0) {
205: packet_timeout_ms = -1;
206: return;
207: }
208: if ((INT_MAX / 1000) / count < timeout)
209: packet_timeout_ms = INT_MAX;
210: else
211: packet_timeout_ms = timeout * count * 1000;
212: }
213:
1.159 markus 214: static void
215: packet_stop_discard(void)
216: {
217: if (packet_discard_mac) {
218: char buf[1024];
219:
220: memset(buf, 'a', sizeof(buf));
221: while (buffer_len(&incoming_packet) < PACKET_MAX_SIZE)
222: buffer_append(&incoming_packet, buf, sizeof(buf));
223: (void) mac_compute(packet_discard_mac,
224: p_read.seqnr,
225: buffer_ptr(&incoming_packet),
226: PACKET_MAX_SIZE);
227: }
228: logit("Finished discarding for %.200s", get_remote_ipaddr());
229: cleanup_exit(255);
230: }
231:
232: static void
233: packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard)
234: {
1.160 ! markus 235: if (enc == NULL || !cipher_is_cbc(enc->cipher))
1.159 markus 236: packet_disconnect("Packet corrupt");
237: if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
238: packet_discard_mac = mac;
239: if (buffer_len(&input) >= discard)
240: packet_stop_discard();
241: packet_discard = discard - buffer_len(&input);
242: }
243:
1.19 markus 244: /* Returns 1 if remote host is connected via socket, 0 if not. */
245:
246: int
1.73 itojun 247: packet_connection_is_on_socket(void)
1.19 markus 248: {
249: struct sockaddr_storage from, to;
250: socklen_t fromlen, tolen;
251:
252: /* filedescriptors in and out are the same, so it's a socket */
253: if (connection_in == connection_out)
254: return 1;
255: fromlen = sizeof(from);
256: memset(&from, 0, sizeof(from));
1.20 markus 257: if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
1.19 markus 258: return 0;
259: tolen = sizeof(to);
260: memset(&to, 0, sizeof(to));
1.20 markus 261: if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
1.19 markus 262: return 0;
263: if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
264: return 0;
265: if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
266: return 0;
267: return 1;
268: }
269:
1.92 markus 270: /*
1.91 markus 271: * Exports an IV from the CipherContext required to export the key
272: * state back from the unprivileged child to the privileged parent
273: * process.
274: */
275:
276: void
277: packet_get_keyiv(int mode, u_char *iv, u_int len)
278: {
279: CipherContext *cc;
280:
281: if (mode == MODE_OUT)
282: cc = &send_context;
283: else
284: cc = &receive_context;
285:
286: cipher_get_keyiv(cc, iv, len);
287: }
288:
289: int
290: packet_get_keycontext(int mode, u_char *dat)
291: {
292: CipherContext *cc;
1.92 markus 293:
1.91 markus 294: if (mode == MODE_OUT)
295: cc = &send_context;
296: else
297: cc = &receive_context;
298:
299: return (cipher_get_keycontext(cc, dat));
300: }
301:
302: void
303: packet_set_keycontext(int mode, u_char *dat)
304: {
305: CipherContext *cc;
1.92 markus 306:
1.91 markus 307: if (mode == MODE_OUT)
308: cc = &send_context;
309: else
310: cc = &receive_context;
311:
312: cipher_set_keycontext(cc, dat);
313: }
314:
315: int
316: packet_get_keyiv_len(int mode)
317: {
318: CipherContext *cc;
319:
320: if (mode == MODE_OUT)
321: cc = &send_context;
322: else
323: cc = &receive_context;
324:
325: return (cipher_get_keyiv_len(cc));
326: }
1.125 deraadt 327:
1.91 markus 328: void
329: packet_set_iv(int mode, u_char *dat)
330: {
331: CipherContext *cc;
332:
333: if (mode == MODE_OUT)
334: cc = &send_context;
335: else
336: cc = &receive_context;
337:
338: cipher_set_keyiv(cc, dat);
339: }
1.125 deraadt 340:
1.91 markus 341: int
1.107 deraadt 342: packet_get_ssh1_cipher(void)
1.91 markus 343: {
344: return (cipher_get_number(receive_context.cipher));
345: }
346:
1.105 markus 347: void
1.157 markus 348: packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets,
349: u_int64_t *bytes)
1.105 markus 350: {
351: struct packet_state *state;
1.104 markus 352:
1.105 markus 353: state = (mode == MODE_IN) ? &p_read : &p_send;
1.157 markus 354: if (seqnr)
355: *seqnr = state->seqnr;
356: if (blocks)
357: *blocks = state->blocks;
358: if (packets)
359: *packets = state->packets;
360: if (bytes)
361: *bytes = state->bytes;
1.91 markus 362: }
363:
364: void
1.157 markus 365: packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
366: u_int64_t bytes)
1.91 markus 367: {
1.105 markus 368: struct packet_state *state;
369:
370: state = (mode == MODE_IN) ? &p_read : &p_send;
371: state->seqnr = seqnr;
372: state->blocks = blocks;
373: state->packets = packets;
1.157 markus 374: state->bytes = bytes;
1.91 markus 375: }
376:
1.19 markus 377: /* returns 1 if connection is via ipv4 */
378:
379: int
1.73 itojun 380: packet_connection_is_ipv4(void)
1.19 markus 381: {
382: struct sockaddr_storage to;
1.21 deraadt 383: socklen_t tolen = sizeof(to);
1.19 markus 384:
385: memset(&to, 0, sizeof(to));
386: if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
387: return 0;
388: if (to.ss_family != AF_INET)
389: return 0;
390: return 1;
391: }
392:
1.1 deraadt 393: /* Sets the connection into non-blocking mode. */
394:
1.2 provos 395: void
1.73 itojun 396: packet_set_nonblocking(void)
1.1 deraadt 397: {
1.14 markus 398: /* Set the socket into non-blocking mode. */
1.114 djm 399: set_nonblock(connection_in);
1.14 markus 400:
1.114 djm 401: if (connection_out != connection_in)
402: set_nonblock(connection_out);
1.1 deraadt 403: }
404:
405: /* Returns the socket used for reading. */
406:
1.2 provos 407: int
1.73 itojun 408: packet_get_connection_in(void)
1.1 deraadt 409: {
1.14 markus 410: return connection_in;
1.1 deraadt 411: }
412:
413: /* Returns the descriptor used for writing. */
414:
1.2 provos 415: int
1.73 itojun 416: packet_get_connection_out(void)
1.1 deraadt 417: {
1.14 markus 418: return connection_out;
1.1 deraadt 419: }
420:
421: /* Closes the connection and clears and frees internal data structures. */
422:
1.2 provos 423: void
1.73 itojun 424: packet_close(void)
1.1 deraadt 425: {
1.14 markus 426: if (!initialized)
427: return;
428: initialized = 0;
429: if (connection_in == connection_out) {
430: shutdown(connection_out, SHUT_RDWR);
431: close(connection_out);
432: } else {
433: close(connection_in);
434: close(connection_out);
435: }
436: buffer_free(&input);
437: buffer_free(&output);
438: buffer_free(&outgoing_packet);
439: buffer_free(&incoming_packet);
1.60 markus 440: if (compression_buffer_ready) {
1.14 markus 441: buffer_free(&compression_buffer);
442: buffer_compress_uninit();
443: }
1.88 markus 444: cipher_cleanup(&send_context);
445: cipher_cleanup(&receive_context);
1.1 deraadt 446: }
447:
448: /* Sets remote side protocol flags. */
449:
1.2 provos 450: void
1.40 markus 451: packet_set_protocol_flags(u_int protocol_flags)
1.1 deraadt 452: {
1.14 markus 453: remote_protocol_flags = protocol_flags;
1.1 deraadt 454: }
455:
456: /* Returns the remote protocol flags set earlier by the above function. */
457:
1.40 markus 458: u_int
1.73 itojun 459: packet_get_protocol_flags(void)
1.1 deraadt 460: {
1.14 markus 461: return remote_protocol_flags;
1.1 deraadt 462: }
463:
1.16 markus 464: /*
465: * Starts packet compression from the next packet on in both directions.
466: * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
467: */
1.1 deraadt 468:
1.68 itojun 469: static void
470: packet_init_compression(void)
1.60 markus 471: {
472: if (compression_buffer_ready == 1)
473: return;
474: compression_buffer_ready = 1;
475: buffer_init(&compression_buffer);
476: }
477:
1.2 provos 478: void
479: packet_start_compression(int level)
1.1 deraadt 480: {
1.62 markus 481: if (packet_compression && !compat20)
1.14 markus 482: fatal("Compression already enabled.");
483: packet_compression = 1;
1.60 markus 484: packet_init_compression();
485: buffer_compress_init_send(level);
486: buffer_compress_init_recv();
1.1 deraadt 487: }
488:
1.16 markus 489: /*
490: * Causes any further packets to be encrypted using the given key. The same
491: * key is used for both sending and reception. However, both directions are
492: * encrypted independently of each other.
493: */
1.95 markus 494:
1.2 provos 495: void
1.40 markus 496: packet_set_encryption_key(const u_char *key, u_int keylen,
1.37 markus 497: int number)
1.1 deraadt 498: {
1.37 markus 499: Cipher *cipher = cipher_by_number(number);
1.97 deraadt 500:
1.37 markus 501: if (cipher == NULL)
502: fatal("packet_set_encryption_key: unknown cipher number %d", number);
1.25 markus 503: if (keylen < 20)
1.37 markus 504: fatal("packet_set_encryption_key: keylen too small: %d", keylen);
1.95 markus 505: if (keylen > SSH_SESSION_KEY_LENGTH)
506: fatal("packet_set_encryption_key: keylen too big: %d", keylen);
507: memcpy(ssh1_key, key, keylen);
508: ssh1_keylen = keylen;
1.88 markus 509: cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT);
510: cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT);
1.95 markus 511: }
512:
513: u_int
514: packet_get_encryption_key(u_char *key)
515: {
516: if (key == NULL)
517: return (ssh1_keylen);
518: memcpy(key, ssh1_key, ssh1_keylen);
519: return (ssh1_keylen);
1.1 deraadt 520: }
521:
1.62 markus 522: /* Start constructing a packet to send. */
1.2 provos 523: void
1.62 markus 524: packet_start(u_char type)
1.1 deraadt 525: {
1.62 markus 526: u_char buf[9];
527: int len;
1.1 deraadt 528:
1.62 markus 529: DBG(debug("packet_start[%d]", type));
530: len = compat20 ? 6 : 9;
531: memset(buf, 0, len - 1);
532: buf[len - 1] = type;
1.14 markus 533: buffer_clear(&outgoing_packet);
1.62 markus 534: buffer_append(&outgoing_packet, buf, len);
1.25 markus 535: }
536:
1.62 markus 537: /* Append payload. */
1.2 provos 538: void
539: packet_put_char(int value)
1.1 deraadt 540: {
1.14 markus 541: char ch = value;
1.97 deraadt 542:
1.14 markus 543: buffer_append(&outgoing_packet, &ch, 1);
1.1 deraadt 544: }
1.125 deraadt 545:
1.2 provos 546: void
1.40 markus 547: packet_put_int(u_int value)
1.1 deraadt 548: {
1.14 markus 549: buffer_put_int(&outgoing_packet, value);
1.1 deraadt 550: }
1.125 deraadt 551:
1.2 provos 552: void
1.76 stevesk 553: packet_put_string(const void *buf, u_int len)
1.1 deraadt 554: {
1.14 markus 555: buffer_put_string(&outgoing_packet, buf, len);
1.1 deraadt 556: }
1.125 deraadt 557:
1.24 markus 558: void
559: packet_put_cstring(const char *str)
560: {
1.65 markus 561: buffer_put_cstring(&outgoing_packet, str);
1.24 markus 562: }
1.125 deraadt 563:
1.24 markus 564: void
1.76 stevesk 565: packet_put_raw(const void *buf, u_int len)
1.24 markus 566: {
567: buffer_append(&outgoing_packet, buf, len);
568: }
1.125 deraadt 569:
1.2 provos 570: void
1.14 markus 571: packet_put_bignum(BIGNUM * value)
1.1 deraadt 572: {
1.14 markus 573: buffer_put_bignum(&outgoing_packet, value);
1.1 deraadt 574: }
1.125 deraadt 575:
1.24 markus 576: void
577: packet_put_bignum2(BIGNUM * value)
578: {
579: buffer_put_bignum2(&outgoing_packet, value);
580: }
1.1 deraadt 581:
1.16 markus 582: /*
583: * Finalizes and sends the packet. If the encryption key has been set,
584: * encrypts the packet before sending.
585: */
1.14 markus 586:
1.68 itojun 587: static void
1.49 itojun 588: packet_send1(void)
1.1 deraadt 589: {
1.89 markus 590: u_char buf[8], *cp;
1.14 markus 591: int i, padding, len;
1.40 markus 592: u_int checksum;
1.115 avsm 593: u_int32_t rnd = 0;
1.14 markus 594:
1.16 markus 595: /*
596: * If using packet compression, compress the payload of the outgoing
597: * packet.
598: */
1.14 markus 599: if (packet_compression) {
600: buffer_clear(&compression_buffer);
601: /* Skip padding. */
602: buffer_consume(&outgoing_packet, 8);
603: /* padding */
604: buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
605: buffer_compress(&outgoing_packet, &compression_buffer);
606: buffer_clear(&outgoing_packet);
607: buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
1.75 deraadt 608: buffer_len(&compression_buffer));
1.14 markus 609: }
610: /* Compute packet length without padding (add checksum, remove padding). */
611: len = buffer_len(&outgoing_packet) + 4 - 8;
612:
1.32 markus 613: /* Insert padding. Initialized to zero in packet_start1() */
1.14 markus 614: padding = 8 - len % 8;
1.88 markus 615: if (!send_context.plaintext) {
1.14 markus 616: cp = buffer_ptr(&outgoing_packet);
617: for (i = 0; i < padding; i++) {
618: if (i % 4 == 0)
1.115 avsm 619: rnd = arc4random();
620: cp[7 - i] = rnd & 0xff;
621: rnd >>= 8;
1.14 markus 622: }
623: }
624: buffer_consume(&outgoing_packet, 8 - padding);
625:
626: /* Add check bytes. */
1.83 stevesk 627: checksum = ssh_crc32(buffer_ptr(&outgoing_packet),
1.34 deraadt 628: buffer_len(&outgoing_packet));
1.131 djm 629: put_u32(buf, checksum);
1.14 markus 630: buffer_append(&outgoing_packet, buf, 4);
1.1 deraadt 631:
632: #ifdef PACKET_DEBUG
1.14 markus 633: fprintf(stderr, "packet_send plain: ");
634: buffer_dump(&outgoing_packet);
1.1 deraadt 635: #endif
636:
1.14 markus 637: /* Append to output. */
1.131 djm 638: put_u32(buf, len);
1.14 markus 639: buffer_append(&output, buf, 4);
1.76 stevesk 640: cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
1.88 markus 641: cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
1.75 deraadt 642: buffer_len(&outgoing_packet));
1.14 markus 643:
1.1 deraadt 644: #ifdef PACKET_DEBUG
1.14 markus 645: fprintf(stderr, "encrypted: ");
646: buffer_dump(&output);
1.1 deraadt 647: #endif
1.157 markus 648: p_send.packets++;
649: p_send.bytes += len + buffer_len(&outgoing_packet);
1.14 markus 650: buffer_clear(&outgoing_packet);
1.1 deraadt 651:
1.16 markus 652: /*
1.120 djm 653: * Note that the packet is now only buffered in output. It won't be
1.16 markus 654: * actually sent until packet_write_wait or packet_write_poll is
655: * called.
656: */
1.1 deraadt 657: }
658:
1.91 markus 659: void
1.57 markus 660: set_newkeys(int mode)
661: {
662: Enc *enc;
663: Mac *mac;
664: Comp *comp;
665: CipherContext *cc;
1.105 markus 666: u_int64_t *max_blocks;
1.115 avsm 667: int crypt_type;
1.57 markus 668:
1.100 markus 669: debug2("set_newkeys: mode %d", mode);
1.57 markus 670:
1.88 markus 671: if (mode == MODE_OUT) {
672: cc = &send_context;
1.115 avsm 673: crypt_type = CIPHER_ENCRYPT;
1.105 markus 674: p_send.packets = p_send.blocks = 0;
675: max_blocks = &max_blocks_out;
1.88 markus 676: } else {
677: cc = &receive_context;
1.115 avsm 678: crypt_type = CIPHER_DECRYPT;
1.105 markus 679: p_read.packets = p_read.blocks = 0;
680: max_blocks = &max_blocks_in;
1.88 markus 681: }
1.57 markus 682: if (newkeys[mode] != NULL) {
1.100 markus 683: debug("set_newkeys: rekeying");
1.88 markus 684: cipher_cleanup(cc);
1.59 markus 685: enc = &newkeys[mode]->enc;
686: mac = &newkeys[mode]->mac;
687: comp = &newkeys[mode]->comp;
1.148 pvalchev 688: mac_clear(mac);
1.59 markus 689: xfree(enc->name);
690: xfree(enc->iv);
691: xfree(enc->key);
692: xfree(mac->name);
693: xfree(mac->key);
694: xfree(comp->name);
1.58 markus 695: xfree(newkeys[mode]);
1.57 markus 696: }
697: newkeys[mode] = kex_get_newkeys(mode);
698: if (newkeys[mode] == NULL)
699: fatal("newkeys: no keys for mode %d", mode);
700: enc = &newkeys[mode]->enc;
701: mac = &newkeys[mode]->mac;
702: comp = &newkeys[mode]->comp;
1.148 pvalchev 703: if (mac_init(mac) == 0)
1.57 markus 704: mac->enabled = 1;
705: DBG(debug("cipher_init_context: %d", mode));
1.88 markus 706: cipher_init(cc, enc->cipher, enc->key, enc->key_len,
1.115 avsm 707: enc->iv, enc->block_size, crypt_type);
1.91 markus 708: /* Deleting the keys does not gain extra security */
709: /* memset(enc->iv, 0, enc->block_size);
1.147 djm 710: memset(enc->key, 0, enc->key_len);
711: memset(mac->key, 0, mac->key_len); */
1.118 markus 712: if ((comp->type == COMP_ZLIB ||
713: (comp->type == COMP_DELAYED && after_authentication)) &&
714: comp->enabled == 0) {
1.60 markus 715: packet_init_compression();
716: if (mode == MODE_OUT)
717: buffer_compress_init_send(6);
718: else
719: buffer_compress_init_recv();
1.57 markus 720: comp->enabled = 1;
721: }
1.109 markus 722: /*
723: * The 2^(blocksize*2) limit is too expensive for 3DES,
724: * blowfish, etc, so enforce a 1GB limit for small blocksizes.
725: */
726: if (enc->block_size >= 16)
727: *max_blocks = (u_int64_t)1 << (enc->block_size*2);
728: else
729: *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
1.105 markus 730: if (rekey_limit)
731: *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
1.57 markus 732: }
733:
1.16 markus 734: /*
1.118 markus 735: * Delayed compression for SSH2 is enabled after authentication:
1.143 dtucker 736: * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
1.118 markus 737: * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
738: */
739: static void
740: packet_enable_delayed_compress(void)
741: {
742: Comp *comp = NULL;
743: int mode;
744:
745: /*
746: * Remember that we are past the authentication step, so rekeying
747: * with COMP_DELAYED will turn on compression immediately.
748: */
749: after_authentication = 1;
750: for (mode = 0; mode < MODE_MAX; mode++) {
1.145 markus 751: /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
752: if (newkeys[mode] == NULL)
753: continue;
1.118 markus 754: comp = &newkeys[mode]->comp;
755: if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
1.119 markus 756: packet_init_compression();
1.118 markus 757: if (mode == MODE_OUT)
758: buffer_compress_init_send(6);
759: else
760: buffer_compress_init_recv();
761: comp->enabled = 1;
762: }
763: }
764: }
765:
766: /*
1.25 markus 767: * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
768: */
1.68 itojun 769: static void
1.105 markus 770: packet_send2_wrapped(void)
1.25 markus 771: {
1.89 markus 772: u_char type, *cp, *macbuf = NULL;
1.71 markus 773: u_char padlen, pad;
1.40 markus 774: u_int packet_length = 0;
1.71 markus 775: u_int i, len;
1.115 avsm 776: u_int32_t rnd = 0;
1.25 markus 777: Enc *enc = NULL;
778: Mac *mac = NULL;
779: Comp *comp = NULL;
780: int block_size;
781:
1.57 markus 782: if (newkeys[MODE_OUT] != NULL) {
783: enc = &newkeys[MODE_OUT]->enc;
784: mac = &newkeys[MODE_OUT]->mac;
785: comp = &newkeys[MODE_OUT]->comp;
1.25 markus 786: }
1.88 markus 787: block_size = enc ? enc->block_size : 8;
1.25 markus 788:
1.89 markus 789: cp = buffer_ptr(&outgoing_packet);
790: type = cp[5];
1.25 markus 791:
792: #ifdef PACKET_DEBUG
793: fprintf(stderr, "plain: ");
794: buffer_dump(&outgoing_packet);
795: #endif
796:
797: if (comp && comp->enabled) {
798: len = buffer_len(&outgoing_packet);
799: /* skip header, compress only payload */
800: buffer_consume(&outgoing_packet, 5);
801: buffer_clear(&compression_buffer);
802: buffer_compress(&outgoing_packet, &compression_buffer);
803: buffer_clear(&outgoing_packet);
804: buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
805: buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
806: buffer_len(&compression_buffer));
807: DBG(debug("compression: raw %d compressed %d", len,
808: buffer_len(&outgoing_packet)));
809: }
810:
811: /* sizeof (packet_len + pad_len + payload) */
812: len = buffer_len(&outgoing_packet);
813:
814: /*
815: * calc size of padding, alloc space, get random data,
816: * minimum padding is 4 bytes
817: */
818: padlen = block_size - (len % block_size);
819: if (padlen < 4)
820: padlen += block_size;
1.71 markus 821: if (extra_pad) {
822: /* will wrap if extra_pad+padlen > 255 */
823: extra_pad = roundup(extra_pad, block_size);
824: pad = extra_pad - ((len + padlen) % extra_pad);
1.93 markus 825: debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
1.71 markus 826: pad, len, padlen, extra_pad);
827: padlen += pad;
828: extra_pad = 0;
829: }
1.76 stevesk 830: cp = buffer_append_space(&outgoing_packet, padlen);
1.88 markus 831: if (enc && !send_context.plaintext) {
1.32 markus 832: /* random padding */
1.25 markus 833: for (i = 0; i < padlen; i++) {
834: if (i % 4 == 0)
1.115 avsm 835: rnd = arc4random();
836: cp[i] = rnd & 0xff;
837: rnd >>= 8;
1.25 markus 838: }
1.32 markus 839: } else {
840: /* clear padding */
841: memset(cp, 0, padlen);
1.25 markus 842: }
843: /* packet_length includes payload, padding and padding length field */
844: packet_length = buffer_len(&outgoing_packet) - 4;
1.89 markus 845: cp = buffer_ptr(&outgoing_packet);
1.131 djm 846: put_u32(cp, packet_length);
1.89 markus 847: cp[4] = padlen;
1.25 markus 848: DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
849:
850: /* compute MAC over seqnr and packet(length fields, payload, padding) */
851: if (mac && mac->enabled) {
1.105 markus 852: macbuf = mac_compute(mac, p_send.seqnr,
1.83 stevesk 853: buffer_ptr(&outgoing_packet),
1.50 markus 854: buffer_len(&outgoing_packet));
1.105 markus 855: DBG(debug("done calc MAC out #%d", p_send.seqnr));
1.25 markus 856: }
857: /* encrypt packet and append to output buffer. */
1.76 stevesk 858: cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
1.88 markus 859: cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
1.25 markus 860: buffer_len(&outgoing_packet));
861: /* append unencrypted MAC */
862: if (mac && mac->enabled)
1.130 deraadt 863: buffer_append(&output, macbuf, mac->mac_len);
1.25 markus 864: #ifdef PACKET_DEBUG
865: fprintf(stderr, "encrypted: ");
866: buffer_dump(&output);
867: #endif
1.29 markus 868: /* increment sequence number for outgoing packets */
1.105 markus 869: if (++p_send.seqnr == 0)
1.106 itojun 870: logit("outgoing seqnr wraps around");
1.105 markus 871: if (++p_send.packets == 0)
872: if (!(datafellows & SSH_BUG_NOREKEY))
873: fatal("XXX too many packets with same key");
874: p_send.blocks += (packet_length + 4) / block_size;
1.157 markus 875: p_send.bytes += packet_length + 4;
1.25 markus 876: buffer_clear(&outgoing_packet);
877:
1.57 markus 878: if (type == SSH2_MSG_NEWKEYS)
879: set_newkeys(MODE_OUT);
1.118 markus 880: else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side)
881: packet_enable_delayed_compress();
1.25 markus 882: }
883:
1.105 markus 884: static void
885: packet_send2(void)
886: {
887: static int rekeying = 0;
888: struct packet *p;
889: u_char type, *cp;
890:
891: cp = buffer_ptr(&outgoing_packet);
892: type = cp[5];
893:
894: /* during rekeying we can only send key exchange messages */
895: if (rekeying) {
896: if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
897: (type <= SSH2_MSG_TRANSPORT_MAX))) {
898: debug("enqueue packet: %u", type);
899: p = xmalloc(sizeof(*p));
900: p->type = type;
901: memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
902: buffer_init(&outgoing_packet);
903: TAILQ_INSERT_TAIL(&outgoing, p, next);
904: return;
905: }
906: }
907:
908: /* rekeying starts with sending KEXINIT */
909: if (type == SSH2_MSG_KEXINIT)
910: rekeying = 1;
911:
912: packet_send2_wrapped();
913:
914: /* after a NEWKEYS message we can send the complete queue */
915: if (type == SSH2_MSG_NEWKEYS) {
916: rekeying = 0;
917: while ((p = TAILQ_FIRST(&outgoing))) {
918: type = p->type;
919: debug("dequeue packet: %u", type);
920: buffer_free(&outgoing_packet);
921: memcpy(&outgoing_packet, &p->payload,
922: sizeof(Buffer));
923: TAILQ_REMOVE(&outgoing, p, next);
924: xfree(p);
925: packet_send2_wrapped();
926: }
927: }
928: }
929:
1.25 markus 930: void
1.73 itojun 931: packet_send(void)
1.25 markus 932: {
1.62 markus 933: if (compat20)
1.25 markus 934: packet_send2();
935: else
936: packet_send1();
937: DBG(debug("packet_send done"));
938: }
939:
940: /*
1.16 markus 941: * Waits until a packet has been received, and returns its type. Note that
942: * no other data is processed until this returns, so this function should not
943: * be used during the interactive session.
944: */
1.1 deraadt 945:
1.2 provos 946: int
1.82 markus 947: packet_read_seqnr(u_int32_t *seqnr_p)
1.1 deraadt 948: {
1.154 dtucker 949: int type, len, ret, ms_remain;
1.56 millert 950: fd_set *setp;
1.14 markus 951: char buf[8192];
1.155 deraadt 952: struct timeval timeout, start, *timeoutp = NULL;
953:
1.25 markus 954: DBG(debug("packet_read()"));
1.14 markus 955:
1.127 djm 956: setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS),
1.56 millert 957: sizeof(fd_mask));
958:
1.14 markus 959: /* Since we are blocking, ensure that all written packets have been sent. */
960: packet_write_wait();
961:
962: /* Stay in the loop until we have received a complete packet. */
963: for (;;) {
964: /* Try to read a packet from the buffer. */
1.82 markus 965: type = packet_read_poll_seqnr(seqnr_p);
1.62 markus 966: if (!compat20 && (
1.32 markus 967: type == SSH_SMSG_SUCCESS
1.14 markus 968: || type == SSH_SMSG_FAILURE
969: || type == SSH_CMSG_EOF
1.32 markus 970: || type == SSH_CMSG_EXIT_CONFIRMATION))
1.79 markus 971: packet_check_eom();
1.14 markus 972: /* If we got a packet, return it. */
1.56 millert 973: if (type != SSH_MSG_NONE) {
974: xfree(setp);
1.14 markus 975: return type;
1.56 millert 976: }
1.16 markus 977: /*
978: * Otherwise, wait for some data to arrive, add it to the
979: * buffer, and try again.
980: */
1.56 millert 981: memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
982: sizeof(fd_mask));
983: FD_SET(connection_in, setp);
1.16 markus 984:
1.154 dtucker 985: if (packet_timeout_ms > 0) {
986: ms_remain = packet_timeout_ms;
987: timeoutp = &timeout;
988: }
1.14 markus 989: /* Wait for some data to arrive. */
1.154 dtucker 990: for (;;) {
991: if (packet_timeout_ms != -1) {
992: ms_to_timeval(&timeout, ms_remain);
993: gettimeofday(&start, NULL);
994: }
995: if ((ret = select(connection_in + 1, setp, NULL,
996: NULL, timeoutp)) >= 0)
997: break;
998: if (errno != EAGAIN && errno != EINTR)
999: break;
1000: if (packet_timeout_ms == -1)
1001: continue;
1002: ms_subtract_diff(&start, &ms_remain);
1003: if (ms_remain <= 0) {
1004: ret = 0;
1005: break;
1006: }
1007: }
1008: if (ret == 0) {
1009: logit("Connection to %.200s timed out while "
1010: "waiting to read", get_remote_ipaddr());
1011: cleanup_exit(255);
1012: }
1.14 markus 1013: /* Read data from the socket. */
1014: len = read(connection_in, buf, sizeof(buf));
1.18 markus 1015: if (len == 0) {
1.106 itojun 1016: logit("Connection closed by %.200s", get_remote_ipaddr());
1.112 markus 1017: cleanup_exit(255);
1.18 markus 1018: }
1.14 markus 1019: if (len < 0)
1020: fatal("Read from socket failed: %.100s", strerror(errno));
1021: /* Append it to the buffer. */
1022: packet_process_incoming(buf, len);
1023: }
1024: /* NOTREACHED */
1.1 deraadt 1025: }
1026:
1.77 djm 1027: int
1.82 markus 1028: packet_read(void)
1.77 djm 1029: {
1.82 markus 1030: return packet_read_seqnr(NULL);
1.77 djm 1031: }
1032:
1.16 markus 1033: /*
1034: * Waits until a packet has been received, verifies that its type matches
1035: * that given, and gives a fatal error and exits if there is a mismatch.
1036: */
1.1 deraadt 1037:
1.2 provos 1038: void
1.82 markus 1039: packet_read_expect(int expected_type)
1.1 deraadt 1040: {
1.14 markus 1041: int type;
1.1 deraadt 1042:
1.82 markus 1043: type = packet_read();
1.14 markus 1044: if (type != expected_type)
1045: packet_disconnect("Protocol error: expected packet type %d, got %d",
1.25 markus 1046: expected_type, type);
1.1 deraadt 1047: }
1048:
1049: /* Checks if a full packet is available in the data received so far via
1.14 markus 1050: * packet_process_incoming. If so, reads the packet; otherwise returns
1051: * SSH_MSG_NONE. This does not wait for data from the connection.
1052: *
1.150 dtucker 1053: * SSH_MSG_DISCONNECT is handled specially here. Also,
1054: * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1055: * to higher levels.
1.14 markus 1056: */
1.1 deraadt 1057:
1.68 itojun 1058: static int
1.82 markus 1059: packet_read_poll1(void)
1.1 deraadt 1060: {
1.40 markus 1061: u_int len, padded_len;
1.89 markus 1062: u_char *cp, type;
1.40 markus 1063: u_int checksum, stored_checksum;
1.14 markus 1064:
1065: /* Check if input size is less than minimum packet size. */
1066: if (buffer_len(&input) < 4 + 8)
1067: return SSH_MSG_NONE;
1068: /* Get length of incoming packet. */
1.89 markus 1069: cp = buffer_ptr(&input);
1.131 djm 1070: len = get_u32(cp);
1.14 markus 1071: if (len < 1 + 2 + 2 || len > 256 * 1024)
1.98 markus 1072: packet_disconnect("Bad packet length %u.", len);
1.14 markus 1073: padded_len = (len + 8) & ~7;
1074:
1075: /* Check if the packet has been entirely received. */
1076: if (buffer_len(&input) < 4 + padded_len)
1077: return SSH_MSG_NONE;
1078:
1079: /* The entire packet is in buffer. */
1080:
1081: /* Consume packet length. */
1082: buffer_consume(&input, 4);
1083:
1.62 markus 1084: /*
1085: * Cryptographic attack detector for ssh
1086: * (C)1998 CORE-SDI, Buenos Aires Argentina
1087: * Ariel Futoransky(futo@core-sdi.com)
1088: */
1.144 djm 1089: if (!receive_context.plaintext) {
1090: switch (detect_attack(buffer_ptr(&input), padded_len)) {
1091: case DEATTACK_DETECTED:
1092: packet_disconnect("crc32 compensation attack: "
1093: "network attack detected");
1094: case DEATTACK_DOS_DETECTED:
1095: packet_disconnect("deattack denial of "
1096: "service detected");
1097: }
1098: }
1.62 markus 1099:
1100: /* Decrypt data to incoming_packet. */
1.14 markus 1101: buffer_clear(&incoming_packet);
1.76 stevesk 1102: cp = buffer_append_space(&incoming_packet, padded_len);
1.88 markus 1103: cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
1.62 markus 1104:
1.14 markus 1105: buffer_consume(&input, padded_len);
1.1 deraadt 1106:
1107: #ifdef PACKET_DEBUG
1.14 markus 1108: fprintf(stderr, "read_poll plain: ");
1109: buffer_dump(&incoming_packet);
1.1 deraadt 1110: #endif
1111:
1.14 markus 1112: /* Compute packet checksum. */
1.83 stevesk 1113: checksum = ssh_crc32(buffer_ptr(&incoming_packet),
1.25 markus 1114: buffer_len(&incoming_packet) - 4);
1.14 markus 1115:
1116: /* Skip padding. */
1117: buffer_consume(&incoming_packet, 8 - len % 8);
1118:
1119: /* Test check bytes. */
1120: if (len != buffer_len(&incoming_packet))
1.77 djm 1121: packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1.25 markus 1122: len, buffer_len(&incoming_packet));
1.14 markus 1123:
1.89 markus 1124: cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
1.131 djm 1125: stored_checksum = get_u32(cp);
1.14 markus 1126: if (checksum != stored_checksum)
1127: packet_disconnect("Corrupted check bytes on input.");
1128: buffer_consume_end(&incoming_packet, 4);
1129:
1130: if (packet_compression) {
1131: buffer_clear(&compression_buffer);
1132: buffer_uncompress(&incoming_packet, &compression_buffer);
1133: buffer_clear(&incoming_packet);
1134: buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1.25 markus 1135: buffer_len(&compression_buffer));
1.14 markus 1136: }
1.157 markus 1137: p_read.packets++;
1138: p_read.bytes += padded_len + 4;
1.62 markus 1139: type = buffer_get_char(&incoming_packet);
1.116 markus 1140: if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1141: packet_disconnect("Invalid ssh1 packet type: %d", type);
1.62 markus 1142: return type;
1.1 deraadt 1143: }
1.14 markus 1144:
1.68 itojun 1145: static int
1.82 markus 1146: packet_read_poll2(u_int32_t *seqnr_p)
1.25 markus 1147: {
1.50 markus 1148: static u_int packet_length = 0;
1.40 markus 1149: u_int padlen, need;
1.89 markus 1150: u_char *macbuf, *cp, type;
1.117 djm 1151: u_int maclen, block_size;
1.25 markus 1152: Enc *enc = NULL;
1153: Mac *mac = NULL;
1154: Comp *comp = NULL;
1155:
1.159 markus 1156: if (packet_discard)
1157: return SSH_MSG_NONE;
1158:
1.57 markus 1159: if (newkeys[MODE_IN] != NULL) {
1160: enc = &newkeys[MODE_IN]->enc;
1161: mac = &newkeys[MODE_IN]->mac;
1162: comp = &newkeys[MODE_IN]->comp;
1.25 markus 1163: }
1164: maclen = mac && mac->enabled ? mac->mac_len : 0;
1.88 markus 1165: block_size = enc ? enc->block_size : 8;
1.25 markus 1166:
1167: if (packet_length == 0) {
1168: /*
1169: * check if input size is less than the cipher block size,
1170: * decrypt first block and extract length of incoming packet
1171: */
1172: if (buffer_len(&input) < block_size)
1173: return SSH_MSG_NONE;
1174: buffer_clear(&incoming_packet);
1.76 stevesk 1175: cp = buffer_append_space(&incoming_packet, block_size);
1.88 markus 1176: cipher_crypt(&receive_context, cp, buffer_ptr(&input),
1.25 markus 1177: block_size);
1.89 markus 1178: cp = buffer_ptr(&incoming_packet);
1.131 djm 1179: packet_length = get_u32(cp);
1.159 markus 1180: if (packet_length < 1 + 4 || packet_length > PACKET_MAX_SIZE) {
1.110 markus 1181: #ifdef PACKET_DEBUG
1.25 markus 1182: buffer_dump(&incoming_packet);
1.110 markus 1183: #endif
1.159 markus 1184: logit("Bad packet length %u.", packet_length);
1185: packet_start_discard(enc, mac, packet_length,
1186: PACKET_MAX_SIZE);
1187: return SSH_MSG_NONE;
1.25 markus 1188: }
1.98 markus 1189: DBG(debug("input: packet len %u", packet_length+4));
1.25 markus 1190: buffer_consume(&input, block_size);
1191: }
1192: /* we have a partial packet of block_size bytes */
1193: need = 4 + packet_length - block_size;
1194: DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1195: need, maclen));
1.158 markus 1196: if (need % block_size != 0) {
1197: logit("padding error: need %d block %d mod %d",
1.25 markus 1198: need, block_size, need % block_size);
1.159 markus 1199: packet_start_discard(enc, mac, packet_length,
1200: PACKET_MAX_SIZE - block_size);
1201: return SSH_MSG_NONE;
1.158 markus 1202: }
1.25 markus 1203: /*
1204: * check if the entire packet has been received and
1205: * decrypt into incoming_packet
1206: */
1207: if (buffer_len(&input) < need + maclen)
1208: return SSH_MSG_NONE;
1209: #ifdef PACKET_DEBUG
1210: fprintf(stderr, "read_poll enc/full: ");
1211: buffer_dump(&input);
1212: #endif
1.76 stevesk 1213: cp = buffer_append_space(&incoming_packet, need);
1.88 markus 1214: cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
1.25 markus 1215: buffer_consume(&input, need);
1216: /*
1217: * compute MAC over seqnr and packet,
1218: * increment sequence number for incoming packet
1219: */
1.29 markus 1220: if (mac && mac->enabled) {
1.105 markus 1221: macbuf = mac_compute(mac, p_read.seqnr,
1.83 stevesk 1222: buffer_ptr(&incoming_packet),
1.50 markus 1223: buffer_len(&incoming_packet));
1.159 markus 1224: if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) {
1225: logit("Corrupted MAC on input.");
1226: if (need > PACKET_MAX_SIZE)
1227: fatal("internal error need %d", need);
1228: packet_start_discard(enc, mac, packet_length,
1229: PACKET_MAX_SIZE - need);
1230: return SSH_MSG_NONE;
1231: }
1232:
1.105 markus 1233: DBG(debug("MAC #%d ok", p_read.seqnr));
1.25 markus 1234: buffer_consume(&input, mac->mac_len);
1235: }
1.159 markus 1236: /* XXX now it's safe to use fatal/packet_disconnect */
1.77 djm 1237: if (seqnr_p != NULL)
1.105 markus 1238: *seqnr_p = p_read.seqnr;
1239: if (++p_read.seqnr == 0)
1.106 itojun 1240: logit("incoming seqnr wraps around");
1.105 markus 1241: if (++p_read.packets == 0)
1242: if (!(datafellows & SSH_BUG_NOREKEY))
1243: fatal("XXX too many packets with same key");
1244: p_read.blocks += (packet_length + 4) / block_size;
1.157 markus 1245: p_read.bytes += packet_length + 4;
1.25 markus 1246:
1247: /* get padlen */
1.76 stevesk 1248: cp = buffer_ptr(&incoming_packet);
1.89 markus 1249: padlen = cp[4];
1.25 markus 1250: DBG(debug("input: padlen %d", padlen));
1251: if (padlen < 4)
1252: packet_disconnect("Corrupted padlen %d on input.", padlen);
1253:
1254: /* skip packet size + padlen, discard padding */
1255: buffer_consume(&incoming_packet, 4 + 1);
1256: buffer_consume_end(&incoming_packet, padlen);
1257:
1258: DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
1259: if (comp && comp->enabled) {
1260: buffer_clear(&compression_buffer);
1261: buffer_uncompress(&incoming_packet, &compression_buffer);
1262: buffer_clear(&incoming_packet);
1263: buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1264: buffer_len(&compression_buffer));
1.97 deraadt 1265: DBG(debug("input: len after de-compress %d",
1266: buffer_len(&incoming_packet)));
1.25 markus 1267: }
1268: /*
1269: * get packet type, implies consume.
1270: * return length of payload (without type field)
1271: */
1.62 markus 1272: type = buffer_get_char(&incoming_packet);
1.116 markus 1273: if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1274: packet_disconnect("Invalid ssh2 packet type: %d", type);
1.57 markus 1275: if (type == SSH2_MSG_NEWKEYS)
1276: set_newkeys(MODE_IN);
1.118 markus 1277: else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side)
1278: packet_enable_delayed_compress();
1.25 markus 1279: #ifdef PACKET_DEBUG
1.55 deraadt 1280: fprintf(stderr, "read/plain[%d]:\r\n", type);
1.25 markus 1281: buffer_dump(&incoming_packet);
1282: #endif
1.62 markus 1283: /* reset for next packet */
1284: packet_length = 0;
1285: return type;
1.25 markus 1286: }
1287:
1288: int
1.82 markus 1289: packet_read_poll_seqnr(u_int32_t *seqnr_p)
1.25 markus 1290: {
1.96 deraadt 1291: u_int reason, seqnr;
1.62 markus 1292: u_char type;
1.25 markus 1293: char *msg;
1.62 markus 1294:
1.25 markus 1295: for (;;) {
1.62 markus 1296: if (compat20) {
1.82 markus 1297: type = packet_read_poll2(seqnr_p);
1.153 djm 1298: if (type) {
1299: keep_alive_timeouts = 0;
1.25 markus 1300: DBG(debug("received packet type %d", type));
1.153 djm 1301: }
1.74 deraadt 1302: switch (type) {
1.150 dtucker 1303: case SSH2_MSG_IGNORE:
1.151 dtucker 1304: debug3("Received SSH2_MSG_IGNORE");
1.150 dtucker 1305: break;
1.25 markus 1306: case SSH2_MSG_DEBUG:
1307: packet_get_char();
1308: msg = packet_get_string(NULL);
1309: debug("Remote: %.900s", msg);
1310: xfree(msg);
1311: msg = packet_get_string(NULL);
1312: xfree(msg);
1313: break;
1314: case SSH2_MSG_DISCONNECT:
1315: reason = packet_get_int();
1316: msg = packet_get_string(NULL);
1.106 itojun 1317: logit("Received disconnect from %s: %u: %.400s",
1.96 deraadt 1318: get_remote_ipaddr(), reason, msg);
1.25 markus 1319: xfree(msg);
1.112 markus 1320: cleanup_exit(255);
1.84 markus 1321: break;
1322: case SSH2_MSG_UNIMPLEMENTED:
1323: seqnr = packet_get_int();
1.96 deraadt 1324: debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1325: seqnr);
1.150 dtucker 1326: break;
1.25 markus 1327: default:
1328: return type;
1.48 stevesk 1329: }
1.25 markus 1330: } else {
1.82 markus 1331: type = packet_read_poll1();
1.74 deraadt 1332: switch (type) {
1.25 markus 1333: case SSH_MSG_IGNORE:
1334: break;
1335: case SSH_MSG_DEBUG:
1336: msg = packet_get_string(NULL);
1337: debug("Remote: %.900s", msg);
1338: xfree(msg);
1339: break;
1340: case SSH_MSG_DISCONNECT:
1341: msg = packet_get_string(NULL);
1.106 itojun 1342: logit("Received disconnect from %s: %.400s",
1.96 deraadt 1343: get_remote_ipaddr(), msg);
1.112 markus 1344: cleanup_exit(255);
1.25 markus 1345: break;
1346: default:
1.62 markus 1347: if (type)
1.25 markus 1348: DBG(debug("received packet type %d", type));
1349: return type;
1.48 stevesk 1350: }
1.25 markus 1351: }
1352: }
1.77 djm 1353: }
1354:
1355: int
1.82 markus 1356: packet_read_poll(void)
1.77 djm 1357: {
1.82 markus 1358: return packet_read_poll_seqnr(NULL);
1.25 markus 1359: }
1360:
1.16 markus 1361: /*
1362: * Buffers the given amount of input characters. This is intended to be used
1363: * together with packet_read_poll.
1364: */
1.1 deraadt 1365:
1.2 provos 1366: void
1.40 markus 1367: packet_process_incoming(const char *buf, u_int len)
1.1 deraadt 1368: {
1.159 markus 1369: if (packet_discard) {
1370: keep_alive_timeouts = 0; /* ?? */
1371: if (len >= packet_discard)
1372: packet_stop_discard();
1373: packet_discard -= len;
1374: return;
1375: }
1.14 markus 1376: buffer_append(&input, buf, len);
1.1 deraadt 1377: }
1378:
1379: /* Returns a character from the packet. */
1380:
1.40 markus 1381: u_int
1.73 itojun 1382: packet_get_char(void)
1.1 deraadt 1383: {
1.14 markus 1384: char ch;
1.97 deraadt 1385:
1.14 markus 1386: buffer_get(&incoming_packet, &ch, 1);
1.40 markus 1387: return (u_char) ch;
1.1 deraadt 1388: }
1389:
1390: /* Returns an integer from the packet data. */
1391:
1.40 markus 1392: u_int
1.73 itojun 1393: packet_get_int(void)
1.1 deraadt 1394: {
1.14 markus 1395: return buffer_get_int(&incoming_packet);
1.1 deraadt 1396: }
1397:
1.16 markus 1398: /*
1399: * Returns an arbitrary precision integer from the packet data. The integer
1400: * must have been initialized before this call.
1401: */
1.1 deraadt 1402:
1.2 provos 1403: void
1.80 markus 1404: packet_get_bignum(BIGNUM * value)
1.1 deraadt 1405: {
1.81 markus 1406: buffer_get_bignum(&incoming_packet, value);
1.24 markus 1407: }
1408:
1409: void
1.80 markus 1410: packet_get_bignum2(BIGNUM * value)
1.24 markus 1411: {
1.81 markus 1412: buffer_get_bignum2(&incoming_packet, value);
1.24 markus 1413: }
1414:
1.76 stevesk 1415: void *
1.117 djm 1416: packet_get_raw(u_int *length_ptr)
1.24 markus 1417: {
1.117 djm 1418: u_int bytes = buffer_len(&incoming_packet);
1.97 deraadt 1419:
1.24 markus 1420: if (length_ptr != NULL)
1421: *length_ptr = bytes;
1422: return buffer_ptr(&incoming_packet);
1.28 markus 1423: }
1424:
1425: int
1426: packet_remaining(void)
1427: {
1428: return buffer_len(&incoming_packet);
1.1 deraadt 1429: }
1430:
1.16 markus 1431: /*
1432: * Returns a string from the packet data. The string is allocated using
1433: * xmalloc; it is the responsibility of the calling program to free it when
1434: * no longer needed. The length_ptr argument may be NULL, or point to an
1435: * integer into which the length of the string is stored.
1436: */
1.1 deraadt 1437:
1.76 stevesk 1438: void *
1.40 markus 1439: packet_get_string(u_int *length_ptr)
1.1 deraadt 1440: {
1.14 markus 1441: return buffer_get_string(&incoming_packet, length_ptr);
1.152 markus 1442: }
1443:
1444: void *
1445: packet_get_string_ptr(u_int *length_ptr)
1446: {
1447: return buffer_get_string_ptr(&incoming_packet, length_ptr);
1.1 deraadt 1448: }
1449:
1.16 markus 1450: /*
1451: * Sends a diagnostic message from the server to the client. This message
1452: * can be sent at any time (but not while constructing another message). The
1453: * message is printed immediately, but only if the client is being executed
1454: * in verbose mode. These messages are primarily intended to ease debugging
1455: * authentication problems. The length of the formatted message must not
1456: * exceed 1024 bytes. This will automatically call packet_write_wait.
1457: */
1.1 deraadt 1458:
1.2 provos 1459: void
1.14 markus 1460: packet_send_debug(const char *fmt,...)
1.1 deraadt 1461: {
1.14 markus 1462: char buf[1024];
1463: va_list args;
1.39 markus 1464:
1465: if (compat20 && (datafellows & SSH_BUG_DEBUG))
1466: return;
1.14 markus 1467:
1468: va_start(args, fmt);
1469: vsnprintf(buf, sizeof(buf), fmt, args);
1470: va_end(args);
1471:
1.30 markus 1472: if (compat20) {
1473: packet_start(SSH2_MSG_DEBUG);
1474: packet_put_char(0); /* bool: always display */
1475: packet_put_cstring(buf);
1476: packet_put_cstring("");
1477: } else {
1478: packet_start(SSH_MSG_DEBUG);
1479: packet_put_cstring(buf);
1480: }
1.14 markus 1481: packet_send();
1482: packet_write_wait();
1.1 deraadt 1483: }
1484:
1.16 markus 1485: /*
1486: * Logs the error plus constructs and sends a disconnect packet, closes the
1487: * connection, and exits. This function never returns. The error message
1488: * should not contain a newline. The length of the formatted message must
1489: * not exceed 1024 bytes.
1490: */
1.1 deraadt 1491:
1.2 provos 1492: void
1.14 markus 1493: packet_disconnect(const char *fmt,...)
1.1 deraadt 1494: {
1.14 markus 1495: char buf[1024];
1496: va_list args;
1497: static int disconnecting = 0;
1.97 deraadt 1498:
1.14 markus 1499: if (disconnecting) /* Guard against recursive invocations. */
1500: fatal("packet_disconnect called recursively.");
1501: disconnecting = 1;
1502:
1.16 markus 1503: /*
1504: * Format the message. Note that the caller must make sure the
1505: * message is of limited size.
1506: */
1.14 markus 1507: va_start(args, fmt);
1508: vsnprintf(buf, sizeof(buf), fmt, args);
1509: va_end(args);
1510:
1.99 markus 1511: /* Display the error locally */
1.106 itojun 1512: logit("Disconnecting: %.100s", buf);
1.99 markus 1513:
1.14 markus 1514: /* Send the disconnect message to the other side, and wait for it to get sent. */
1.25 markus 1515: if (compat20) {
1516: packet_start(SSH2_MSG_DISCONNECT);
1517: packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1518: packet_put_cstring(buf);
1519: packet_put_cstring("");
1520: } else {
1521: packet_start(SSH_MSG_DISCONNECT);
1.65 markus 1522: packet_put_cstring(buf);
1.25 markus 1523: }
1.14 markus 1524: packet_send();
1525: packet_write_wait();
1526:
1527: /* Stop listening for connections. */
1.67 markus 1528: channel_close_all();
1.14 markus 1529:
1530: /* Close the connection. */
1531: packet_close();
1.112 markus 1532: cleanup_exit(255);
1.1 deraadt 1533: }
1534:
1.16 markus 1535: /* Checks if there is any buffered output, and tries to write some of the output. */
1.1 deraadt 1536:
1.2 provos 1537: void
1.73 itojun 1538: packet_write_poll(void)
1.1 deraadt 1539: {
1.14 markus 1540: int len = buffer_len(&output);
1.97 deraadt 1541:
1.14 markus 1542: if (len > 0) {
1543: len = write(connection_out, buffer_ptr(&output), len);
1.156 djm 1544: if (len == -1) {
1545: if (errno == EINTR || errno == EAGAIN)
1.14 markus 1546: return;
1.156 djm 1547: fatal("Write failed: %.100s", strerror(errno));
1.14 markus 1548: }
1.156 djm 1549: if (len == 0)
1550: fatal("Write connection closed");
1.14 markus 1551: buffer_consume(&output, len);
1552: }
1.1 deraadt 1553: }
1554:
1.16 markus 1555: /*
1556: * Calls packet_write_poll repeatedly until all pending output data has been
1557: * written.
1558: */
1.1 deraadt 1559:
1.2 provos 1560: void
1.73 itojun 1561: packet_write_wait(void)
1.1 deraadt 1562: {
1.56 millert 1563: fd_set *setp;
1.154 dtucker 1564: int ret, ms_remain;
1565: struct timeval start, timeout, *timeoutp = NULL;
1.56 millert 1566:
1.127 djm 1567: setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS),
1.56 millert 1568: sizeof(fd_mask));
1.14 markus 1569: packet_write_poll();
1570: while (packet_have_data_to_write()) {
1.56 millert 1571: memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1572: sizeof(fd_mask));
1573: FD_SET(connection_out, setp);
1.154 dtucker 1574:
1575: if (packet_timeout_ms > 0) {
1576: ms_remain = packet_timeout_ms;
1577: timeoutp = &timeout;
1578: }
1579: for (;;) {
1580: if (packet_timeout_ms != -1) {
1581: ms_to_timeval(&timeout, ms_remain);
1582: gettimeofday(&start, NULL);
1583: }
1584: if ((ret = select(connection_out + 1, NULL, setp,
1585: NULL, timeoutp)) >= 0)
1586: break;
1587: if (errno != EAGAIN && errno != EINTR)
1588: break;
1589: if (packet_timeout_ms == -1)
1590: continue;
1591: ms_subtract_diff(&start, &ms_remain);
1592: if (ms_remain <= 0) {
1593: ret = 0;
1594: break;
1595: }
1596: }
1597: if (ret == 0) {
1598: logit("Connection to %.200s timed out while "
1599: "waiting to write", get_remote_ipaddr());
1600: cleanup_exit(255);
1601: }
1.14 markus 1602: packet_write_poll();
1603: }
1.56 millert 1604: xfree(setp);
1.1 deraadt 1605: }
1606:
1607: /* Returns true if there is buffered data to write to the connection. */
1608:
1.2 provos 1609: int
1.73 itojun 1610: packet_have_data_to_write(void)
1.1 deraadt 1611: {
1.14 markus 1612: return buffer_len(&output) != 0;
1.1 deraadt 1613: }
1614:
1615: /* Returns true if there is not too much data to write to the connection. */
1616:
1.2 provos 1617: int
1.73 itojun 1618: packet_not_very_much_data_to_write(void)
1.1 deraadt 1619: {
1.14 markus 1620: if (interactive_mode)
1621: return buffer_len(&output) < 16384;
1622: else
1623: return buffer_len(&output) < 128 * 1024;
1.1 deraadt 1624: }
1625:
1.102 markus 1626: static void
1.101 markus 1627: packet_set_tos(int interactive)
1628: {
1629: int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1630:
1631: if (!packet_connection_is_on_socket() ||
1632: !packet_connection_is_ipv4())
1633: return;
1634: if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos,
1635: sizeof(tos)) < 0)
1636: error("setsockopt IP_TOS %d: %.100s:",
1637: tos, strerror(errno));
1638: }
1639:
1.1 deraadt 1640: /* Informs that the current session is interactive. Sets IP flags for that. */
1641:
1.2 provos 1642: void
1.43 markus 1643: packet_set_interactive(int interactive)
1.1 deraadt 1644: {
1.43 markus 1645: static int called = 0;
1.44 markus 1646:
1.43 markus 1647: if (called)
1648: return;
1649: called = 1;
1.1 deraadt 1650:
1.14 markus 1651: /* Record that we are in interactive mode. */
1652: interactive_mode = interactive;
1.1 deraadt 1653:
1.19 markus 1654: /* Only set socket options if using a socket. */
1655: if (!packet_connection_is_on_socket())
1.14 markus 1656: return;
1.122 dtucker 1657: set_nodelay(connection_in);
1.101 markus 1658: packet_set_tos(interactive);
1.1 deraadt 1659: }
1660:
1661: /* Returns true if the current connection is interactive. */
1662:
1.2 provos 1663: int
1.73 itojun 1664: packet_is_interactive(void)
1.1 deraadt 1665: {
1.14 markus 1666: return interactive_mode;
1.12 markus 1667: }
1668:
1.113 deraadt 1669: int
1.108 markus 1670: packet_set_maxsize(u_int s)
1.12 markus 1671: {
1.14 markus 1672: static int called = 0;
1.97 deraadt 1673:
1.14 markus 1674: if (called) {
1.106 itojun 1675: logit("packet_set_maxsize: called twice: old %d new %d",
1.25 markus 1676: max_packet_size, s);
1.14 markus 1677: return -1;
1678: }
1679: if (s < 4 * 1024 || s > 1024 * 1024) {
1.106 itojun 1680: logit("packet_set_maxsize: bad size %d", s);
1.14 markus 1681: return -1;
1682: }
1.70 markus 1683: called = 1;
1.66 markus 1684: debug("packet_set_maxsize: setting to %d", s);
1.14 markus 1685: max_packet_size = s;
1686: return s;
1.53 markus 1687: }
1688:
1.71 markus 1689: /* roundup current message to pad bytes */
1690: void
1691: packet_add_padding(u_char pad)
1692: {
1693: extra_pad = pad;
1694: }
1695:
1.53 markus 1696: /*
1697: * 9.2. Ignored Data Message
1.61 markus 1698: *
1.53 markus 1699: * byte SSH_MSG_IGNORE
1700: * string data
1.61 markus 1701: *
1.53 markus 1702: * All implementations MUST understand (and ignore) this message at any
1703: * time (after receiving the protocol version). No implementation is
1704: * required to send them. This message can be used as an additional
1705: * protection measure against advanced traffic analysis techniques.
1706: */
1.54 markus 1707: void
1708: packet_send_ignore(int nbytes)
1709: {
1.115 avsm 1710: u_int32_t rnd = 0;
1.54 markus 1711: int i;
1712:
1713: packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1.53 markus 1714: packet_put_int(nbytes);
1.75 deraadt 1715: for (i = 0; i < nbytes; i++) {
1.53 markus 1716: if (i % 4 == 0)
1.115 avsm 1717: rnd = arc4random();
1.129 deraadt 1718: packet_put_char((u_char)rnd & 0xff);
1.115 avsm 1719: rnd >>= 8;
1.53 markus 1720: }
1.105 markus 1721: }
1722:
1.113 deraadt 1723: #define MAX_PACKETS (1U<<31)
1.105 markus 1724: int
1725: packet_need_rekeying(void)
1726: {
1727: if (datafellows & SSH_BUG_NOREKEY)
1728: return 0;
1729: return
1730: (p_send.packets > MAX_PACKETS) ||
1731: (p_read.packets > MAX_PACKETS) ||
1732: (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
1733: (max_blocks_in && (p_read.blocks > max_blocks_in));
1734: }
1735:
1736: void
1737: packet_set_rekey_limit(u_int32_t bytes)
1738: {
1739: rekey_limit = bytes;
1.118 markus 1740: }
1741:
1742: void
1743: packet_set_server(void)
1744: {
1745: server_side = 1;
1746: }
1747:
1748: void
1749: packet_set_authenticated(void)
1750: {
1751: after_authentication = 1;
1.1 deraadt 1752: }
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