1 /* 2 * Author: Tatu Ylonen <ylo@cs.hut.fi> 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * This file contains code implementing the packet protocol and communication 6 * with the other side. This same code is used both on client and server side. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * 15 * SSH2 packet format added by Markus Friedl. 16 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 21 * 1. Redistributions of source code must retain the above copyright 22 * notice, this list of conditions and the following disclaimer. 23 * 2. Redistributions in binary form must reproduce the above copyright 24 * notice, this list of conditions and the following disclaimer in the 25 * documentation and/or other materials provided with the distribution. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include "includes.h" 40 RCSID("$OpenBSD: packet.c,v 1.115 2004/06/21 17:36:31 avsm Exp $"); 41 42 #include "openbsd-compat/sys-queue.h" 43 44 #include "xmalloc.h" 45 #include "buffer.h" 46 #include "packet.h" 47 #include "bufaux.h" 48 #include "crc32.h" 49 #include "getput.h" 50 51 #include "compress.h" 52 #include "deattack.h" 53 #include "channels.h" 54 55 #include "compat.h" 56 #include "ssh1.h" 57 #include "ssh2.h" 58 59 #include "cipher.h" 60 #include "kex.h" 61 #include "mac.h" 62 #include "log.h" 63 #include "canohost.h" 64 #include "misc.h" 65 #include "ssh.h" 66 67 #ifdef PACKET_DEBUG 68 #define DBG(x) x 69 #else 70 #define DBG(x) 71 #endif 72 73 /* 74 * This variable contains the file descriptors used for communicating with 75 * the other side. connection_in is used for reading; connection_out for 76 * writing. These can be the same descriptor, in which case it is assumed to 77 * be a socket. 78 */ 79 static int connection_in = -1; 80 static int connection_out = -1; 81 82 /* Protocol flags for the remote side. */ 83 static u_int remote_protocol_flags = 0; 84 85 /* Encryption context for receiving data. This is only used for decryption. */ 86 static CipherContext receive_context; 87 88 /* Encryption context for sending data. This is only used for encryption. */ 89 static CipherContext send_context; 90 91 /* Buffer for raw input data from the socket. */ 92 Buffer input; 93 94 /* Buffer for raw output data going to the socket. */ 95 Buffer output; 96 97 /* Buffer for the partial outgoing packet being constructed. */ 98 static Buffer outgoing_packet; 99 100 /* Buffer for the incoming packet currently being processed. */ 101 static Buffer incoming_packet; 102 103 /* Scratch buffer for packet compression/decompression. */ 104 static Buffer compression_buffer; 105 static int compression_buffer_ready = 0; 106 107 /* Flag indicating whether packet compression/decompression is enabled. */ 108 static int packet_compression = 0; 109 110 /* default maximum packet size */ 111 u_int max_packet_size = 32768; 112 113 /* Flag indicating whether this module has been initialized. */ 114 static int initialized = 0; 115 116 /* Set to true if the connection is interactive. */ 117 static int interactive_mode = 0; 118 119 /* Session key information for Encryption and MAC */ 120 Newkeys *newkeys[MODE_MAX]; 121 static struct packet_state { 122 u_int32_t seqnr; 123 u_int32_t packets; 124 u_int64_t blocks; 125 } p_read, p_send; 126 127 static u_int64_t max_blocks_in, max_blocks_out; 128 static u_int32_t rekey_limit; 129 130 /* Session key for protocol v1 */ 131 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; 132 static u_int ssh1_keylen; 133 134 /* roundup current message to extra_pad bytes */ 135 static u_char extra_pad = 0; 136 137 struct packet { 138 TAILQ_ENTRY(packet) next; 139 u_char type; 140 Buffer payload; 141 }; 142 TAILQ_HEAD(, packet) outgoing; 143 144 /* 145 * Sets the descriptors used for communication. Disables encryption until 146 * packet_set_encryption_key is called. 147 */ 148 void 149 packet_set_connection(int fd_in, int fd_out) 150 { 151 Cipher *none = cipher_by_name("none"); 152 153 if (none == NULL) 154 fatal("packet_set_connection: cannot load cipher 'none'"); 155 connection_in = fd_in; 156 connection_out = fd_out; 157 cipher_init(&send_context, none, (const u_char *)"", 158 0, NULL, 0, CIPHER_ENCRYPT); 159 cipher_init(&receive_context, none, (const u_char *)"", 160 0, NULL, 0, CIPHER_DECRYPT); 161 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; 162 if (!initialized) { 163 initialized = 1; 164 buffer_init(&input); 165 buffer_init(&output); 166 buffer_init(&outgoing_packet); 167 buffer_init(&incoming_packet); 168 TAILQ_INIT(&outgoing); 169 } 170 } 171 172 /* Returns 1 if remote host is connected via socket, 0 if not. */ 173 174 int 175 packet_connection_is_on_socket(void) 176 { 177 struct sockaddr_storage from, to; 178 socklen_t fromlen, tolen; 179 180 /* filedescriptors in and out are the same, so it's a socket */ 181 if (connection_in == connection_out) 182 return 1; 183 fromlen = sizeof(from); 184 memset(&from, 0, sizeof(from)); 185 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) 186 return 0; 187 tolen = sizeof(to); 188 memset(&to, 0, sizeof(to)); 189 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) 190 return 0; 191 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) 192 return 0; 193 if (from.ss_family != AF_INET && from.ss_family != AF_INET6) 194 return 0; 195 return 1; 196 } 197 198 /* 199 * Exports an IV from the CipherContext required to export the key 200 * state back from the unprivileged child to the privileged parent 201 * process. 202 */ 203 204 void 205 packet_get_keyiv(int mode, u_char *iv, u_int len) 206 { 207 CipherContext *cc; 208 209 if (mode == MODE_OUT) 210 cc = &send_context; 211 else 212 cc = &receive_context; 213 214 cipher_get_keyiv(cc, iv, len); 215 } 216 217 int 218 packet_get_keycontext(int mode, u_char *dat) 219 { 220 CipherContext *cc; 221 222 if (mode == MODE_OUT) 223 cc = &send_context; 224 else 225 cc = &receive_context; 226 227 return (cipher_get_keycontext(cc, dat)); 228 } 229 230 void 231 packet_set_keycontext(int mode, u_char *dat) 232 { 233 CipherContext *cc; 234 235 if (mode == MODE_OUT) 236 cc = &send_context; 237 else 238 cc = &receive_context; 239 240 cipher_set_keycontext(cc, dat); 241 } 242 243 int 244 packet_get_keyiv_len(int mode) 245 { 246 CipherContext *cc; 247 248 if (mode == MODE_OUT) 249 cc = &send_context; 250 else 251 cc = &receive_context; 252 253 return (cipher_get_keyiv_len(cc)); 254 } 255 void 256 packet_set_iv(int mode, u_char *dat) 257 { 258 CipherContext *cc; 259 260 if (mode == MODE_OUT) 261 cc = &send_context; 262 else 263 cc = &receive_context; 264 265 cipher_set_keyiv(cc, dat); 266 } 267 int 268 packet_get_ssh1_cipher(void) 269 { 270 return (cipher_get_number(receive_context.cipher)); 271 } 272 273 void 274 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets) 275 { 276 struct packet_state *state; 277 278 state = (mode == MODE_IN) ? &p_read : &p_send; 279 *seqnr = state->seqnr; 280 *blocks = state->blocks; 281 *packets = state->packets; 282 } 283 284 void 285 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets) 286 { 287 struct packet_state *state; 288 289 state = (mode == MODE_IN) ? &p_read : &p_send; 290 state->seqnr = seqnr; 291 state->blocks = blocks; 292 state->packets = packets; 293 } 294 295 /* returns 1 if connection is via ipv4 */ 296 297 int 298 packet_connection_is_ipv4(void) 299 { 300 struct sockaddr_storage to; 301 socklen_t tolen = sizeof(to); 302 303 memset(&to, 0, sizeof(to)); 304 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) 305 return 0; 306 if (to.ss_family == AF_INET) 307 return 1; 308 #ifdef IPV4_IN_IPV6 309 if (to.ss_family == AF_INET6 && 310 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) 311 return 1; 312 #endif 313 return 0; 314 } 315 316 /* Sets the connection into non-blocking mode. */ 317 318 void 319 packet_set_nonblocking(void) 320 { 321 /* Set the socket into non-blocking mode. */ 322 set_nonblock(connection_in); 323 324 if (connection_out != connection_in) 325 set_nonblock(connection_out); 326 } 327 328 /* Returns the socket used for reading. */ 329 330 int 331 packet_get_connection_in(void) 332 { 333 return connection_in; 334 } 335 336 /* Returns the descriptor used for writing. */ 337 338 int 339 packet_get_connection_out(void) 340 { 341 return connection_out; 342 } 343 344 /* Closes the connection and clears and frees internal data structures. */ 345 346 void 347 packet_close(void) 348 { 349 if (!initialized) 350 return; 351 initialized = 0; 352 if (connection_in == connection_out) { 353 shutdown(connection_out, SHUT_RDWR); 354 close(connection_out); 355 } else { 356 close(connection_in); 357 close(connection_out); 358 } 359 buffer_free(&input); 360 buffer_free(&output); 361 buffer_free(&outgoing_packet); 362 buffer_free(&incoming_packet); 363 if (compression_buffer_ready) { 364 buffer_free(&compression_buffer); 365 buffer_compress_uninit(); 366 } 367 cipher_cleanup(&send_context); 368 cipher_cleanup(&receive_context); 369 } 370 371 /* Sets remote side protocol flags. */ 372 373 void 374 packet_set_protocol_flags(u_int protocol_flags) 375 { 376 remote_protocol_flags = protocol_flags; 377 } 378 379 /* Returns the remote protocol flags set earlier by the above function. */ 380 381 u_int 382 packet_get_protocol_flags(void) 383 { 384 return remote_protocol_flags; 385 } 386 387 /* 388 * Starts packet compression from the next packet on in both directions. 389 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. 390 */ 391 392 static void 393 packet_init_compression(void) 394 { 395 if (compression_buffer_ready == 1) 396 return; 397 compression_buffer_ready = 1; 398 buffer_init(&compression_buffer); 399 } 400 401 void 402 packet_start_compression(int level) 403 { 404 if (packet_compression && !compat20) 405 fatal("Compression already enabled."); 406 packet_compression = 1; 407 packet_init_compression(); 408 buffer_compress_init_send(level); 409 buffer_compress_init_recv(); 410 } 411 412 /* 413 * Causes any further packets to be encrypted using the given key. The same 414 * key is used for both sending and reception. However, both directions are 415 * encrypted independently of each other. 416 */ 417 418 void 419 packet_set_encryption_key(const u_char *key, u_int keylen, 420 int number) 421 { 422 Cipher *cipher = cipher_by_number(number); 423 424 if (cipher == NULL) 425 fatal("packet_set_encryption_key: unknown cipher number %d", number); 426 if (keylen < 20) 427 fatal("packet_set_encryption_key: keylen too small: %d", keylen); 428 if (keylen > SSH_SESSION_KEY_LENGTH) 429 fatal("packet_set_encryption_key: keylen too big: %d", keylen); 430 memcpy(ssh1_key, key, keylen); 431 ssh1_keylen = keylen; 432 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); 433 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); 434 } 435 436 u_int 437 packet_get_encryption_key(u_char *key) 438 { 439 if (key == NULL) 440 return (ssh1_keylen); 441 memcpy(key, ssh1_key, ssh1_keylen); 442 return (ssh1_keylen); 443 } 444 445 /* Start constructing a packet to send. */ 446 void 447 packet_start(u_char type) 448 { 449 u_char buf[9]; 450 int len; 451 452 DBG(debug("packet_start[%d]", type)); 453 len = compat20 ? 6 : 9; 454 memset(buf, 0, len - 1); 455 buf[len - 1] = type; 456 buffer_clear(&outgoing_packet); 457 buffer_append(&outgoing_packet, buf, len); 458 } 459 460 /* Append payload. */ 461 void 462 packet_put_char(int value) 463 { 464 char ch = value; 465 466 buffer_append(&outgoing_packet, &ch, 1); 467 } 468 void 469 packet_put_int(u_int value) 470 { 471 buffer_put_int(&outgoing_packet, value); 472 } 473 void 474 packet_put_string(const void *buf, u_int len) 475 { 476 buffer_put_string(&outgoing_packet, buf, len); 477 } 478 void 479 packet_put_cstring(const char *str) 480 { 481 buffer_put_cstring(&outgoing_packet, str); 482 } 483 void 484 packet_put_raw(const void *buf, u_int len) 485 { 486 buffer_append(&outgoing_packet, buf, len); 487 } 488 void 489 packet_put_bignum(BIGNUM * value) 490 { 491 buffer_put_bignum(&outgoing_packet, value); 492 } 493 void 494 packet_put_bignum2(BIGNUM * value) 495 { 496 buffer_put_bignum2(&outgoing_packet, value); 497 } 498 499 /* 500 * Finalizes and sends the packet. If the encryption key has been set, 501 * encrypts the packet before sending. 502 */ 503 504 static void 505 packet_send1(void) 506 { 507 u_char buf[8], *cp; 508 int i, padding, len; 509 u_int checksum; 510 u_int32_t rnd = 0; 511 512 /* 513 * If using packet compression, compress the payload of the outgoing 514 * packet. 515 */ 516 if (packet_compression) { 517 buffer_clear(&compression_buffer); 518 /* Skip padding. */ 519 buffer_consume(&outgoing_packet, 8); 520 /* padding */ 521 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); 522 buffer_compress(&outgoing_packet, &compression_buffer); 523 buffer_clear(&outgoing_packet); 524 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 525 buffer_len(&compression_buffer)); 526 } 527 /* Compute packet length without padding (add checksum, remove padding). */ 528 len = buffer_len(&outgoing_packet) + 4 - 8; 529 530 /* Insert padding. Initialized to zero in packet_start1() */ 531 padding = 8 - len % 8; 532 if (!send_context.plaintext) { 533 cp = buffer_ptr(&outgoing_packet); 534 for (i = 0; i < padding; i++) { 535 if (i % 4 == 0) 536 rnd = arc4random(); 537 cp[7 - i] = rnd & 0xff; 538 rnd >>= 8; 539 } 540 } 541 buffer_consume(&outgoing_packet, 8 - padding); 542 543 /* Add check bytes. */ 544 checksum = ssh_crc32(buffer_ptr(&outgoing_packet), 545 buffer_len(&outgoing_packet)); 546 PUT_32BIT(buf, checksum); 547 buffer_append(&outgoing_packet, buf, 4); 548 549 #ifdef PACKET_DEBUG 550 fprintf(stderr, "packet_send plain: "); 551 buffer_dump(&outgoing_packet); 552 #endif 553 554 /* Append to output. */ 555 PUT_32BIT(buf, len); 556 buffer_append(&output, buf, 4); 557 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 558 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 559 buffer_len(&outgoing_packet)); 560 561 #ifdef PACKET_DEBUG 562 fprintf(stderr, "encrypted: "); 563 buffer_dump(&output); 564 #endif 565 566 buffer_clear(&outgoing_packet); 567 568 /* 569 * Note that the packet is now only buffered in output. It won\'t be 570 * actually sent until packet_write_wait or packet_write_poll is 571 * called. 572 */ 573 } 574 575 void 576 set_newkeys(int mode) 577 { 578 Enc *enc; 579 Mac *mac; 580 Comp *comp; 581 CipherContext *cc; 582 u_int64_t *max_blocks; 583 int crypt_type; 584 585 debug2("set_newkeys: mode %d", mode); 586 587 if (mode == MODE_OUT) { 588 cc = &send_context; 589 crypt_type = CIPHER_ENCRYPT; 590 p_send.packets = p_send.blocks = 0; 591 max_blocks = &max_blocks_out; 592 } else { 593 cc = &receive_context; 594 crypt_type = CIPHER_DECRYPT; 595 p_read.packets = p_read.blocks = 0; 596 max_blocks = &max_blocks_in; 597 } 598 if (newkeys[mode] != NULL) { 599 debug("set_newkeys: rekeying"); 600 cipher_cleanup(cc); 601 enc = &newkeys[mode]->enc; 602 mac = &newkeys[mode]->mac; 603 comp = &newkeys[mode]->comp; 604 memset(mac->key, 0, mac->key_len); 605 xfree(enc->name); 606 xfree(enc->iv); 607 xfree(enc->key); 608 xfree(mac->name); 609 xfree(mac->key); 610 xfree(comp->name); 611 xfree(newkeys[mode]); 612 } 613 newkeys[mode] = kex_get_newkeys(mode); 614 if (newkeys[mode] == NULL) 615 fatal("newkeys: no keys for mode %d", mode); 616 enc = &newkeys[mode]->enc; 617 mac = &newkeys[mode]->mac; 618 comp = &newkeys[mode]->comp; 619 if (mac->md != NULL) 620 mac->enabled = 1; 621 DBG(debug("cipher_init_context: %d", mode)); 622 cipher_init(cc, enc->cipher, enc->key, enc->key_len, 623 enc->iv, enc->block_size, crypt_type); 624 /* Deleting the keys does not gain extra security */ 625 /* memset(enc->iv, 0, enc->block_size); 626 memset(enc->key, 0, enc->key_len); */ 627 if (comp->type != 0 && comp->enabled == 0) { 628 packet_init_compression(); 629 if (mode == MODE_OUT) 630 buffer_compress_init_send(6); 631 else 632 buffer_compress_init_recv(); 633 comp->enabled = 1; 634 } 635 /* 636 * The 2^(blocksize*2) limit is too expensive for 3DES, 637 * blowfish, etc, so enforce a 1GB limit for small blocksizes. 638 */ 639 if (enc->block_size >= 16) 640 *max_blocks = (u_int64_t)1 << (enc->block_size*2); 641 else 642 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; 643 if (rekey_limit) 644 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); 645 } 646 647 /* 648 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) 649 */ 650 static void 651 packet_send2_wrapped(void) 652 { 653 u_char type, *cp, *macbuf = NULL; 654 u_char padlen, pad; 655 u_int packet_length = 0; 656 u_int i, len; 657 u_int32_t rnd = 0; 658 Enc *enc = NULL; 659 Mac *mac = NULL; 660 Comp *comp = NULL; 661 int block_size; 662 663 if (newkeys[MODE_OUT] != NULL) { 664 enc = &newkeys[MODE_OUT]->enc; 665 mac = &newkeys[MODE_OUT]->mac; 666 comp = &newkeys[MODE_OUT]->comp; 667 } 668 block_size = enc ? enc->block_size : 8; 669 670 cp = buffer_ptr(&outgoing_packet); 671 type = cp[5]; 672 673 #ifdef PACKET_DEBUG 674 fprintf(stderr, "plain: "); 675 buffer_dump(&outgoing_packet); 676 #endif 677 678 if (comp && comp->enabled) { 679 len = buffer_len(&outgoing_packet); 680 /* skip header, compress only payload */ 681 buffer_consume(&outgoing_packet, 5); 682 buffer_clear(&compression_buffer); 683 buffer_compress(&outgoing_packet, &compression_buffer); 684 buffer_clear(&outgoing_packet); 685 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); 686 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 687 buffer_len(&compression_buffer)); 688 DBG(debug("compression: raw %d compressed %d", len, 689 buffer_len(&outgoing_packet))); 690 } 691 692 /* sizeof (packet_len + pad_len + payload) */ 693 len = buffer_len(&outgoing_packet); 694 695 /* 696 * calc size of padding, alloc space, get random data, 697 * minimum padding is 4 bytes 698 */ 699 padlen = block_size - (len % block_size); 700 if (padlen < 4) 701 padlen += block_size; 702 if (extra_pad) { 703 /* will wrap if extra_pad+padlen > 255 */ 704 extra_pad = roundup(extra_pad, block_size); 705 pad = extra_pad - ((len + padlen) % extra_pad); 706 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", 707 pad, len, padlen, extra_pad); 708 padlen += pad; 709 extra_pad = 0; 710 } 711 cp = buffer_append_space(&outgoing_packet, padlen); 712 if (enc && !send_context.plaintext) { 713 /* random padding */ 714 for (i = 0; i < padlen; i++) { 715 if (i % 4 == 0) 716 rnd = arc4random(); 717 cp[i] = rnd & 0xff; 718 rnd >>= 8; 719 } 720 } else { 721 /* clear padding */ 722 memset(cp, 0, padlen); 723 } 724 /* packet_length includes payload, padding and padding length field */ 725 packet_length = buffer_len(&outgoing_packet) - 4; 726 cp = buffer_ptr(&outgoing_packet); 727 PUT_32BIT(cp, packet_length); 728 cp[4] = padlen; 729 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); 730 731 /* compute MAC over seqnr and packet(length fields, payload, padding) */ 732 if (mac && mac->enabled) { 733 macbuf = mac_compute(mac, p_send.seqnr, 734 buffer_ptr(&outgoing_packet), 735 buffer_len(&outgoing_packet)); 736 DBG(debug("done calc MAC out #%d", p_send.seqnr)); 737 } 738 /* encrypt packet and append to output buffer. */ 739 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 740 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 741 buffer_len(&outgoing_packet)); 742 /* append unencrypted MAC */ 743 if (mac && mac->enabled) 744 buffer_append(&output, (char *)macbuf, mac->mac_len); 745 #ifdef PACKET_DEBUG 746 fprintf(stderr, "encrypted: "); 747 buffer_dump(&output); 748 #endif 749 /* increment sequence number for outgoing packets */ 750 if (++p_send.seqnr == 0) 751 logit("outgoing seqnr wraps around"); 752 if (++p_send.packets == 0) 753 if (!(datafellows & SSH_BUG_NOREKEY)) 754 fatal("XXX too many packets with same key"); 755 p_send.blocks += (packet_length + 4) / block_size; 756 buffer_clear(&outgoing_packet); 757 758 if (type == SSH2_MSG_NEWKEYS) 759 set_newkeys(MODE_OUT); 760 } 761 762 static void 763 packet_send2(void) 764 { 765 static int rekeying = 0; 766 struct packet *p; 767 u_char type, *cp; 768 769 cp = buffer_ptr(&outgoing_packet); 770 type = cp[5]; 771 772 /* during rekeying we can only send key exchange messages */ 773 if (rekeying) { 774 if (!((type >= SSH2_MSG_TRANSPORT_MIN) && 775 (type <= SSH2_MSG_TRANSPORT_MAX))) { 776 debug("enqueue packet: %u", type); 777 p = xmalloc(sizeof(*p)); 778 p->type = type; 779 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); 780 buffer_init(&outgoing_packet); 781 TAILQ_INSERT_TAIL(&outgoing, p, next); 782 return; 783 } 784 } 785 786 /* rekeying starts with sending KEXINIT */ 787 if (type == SSH2_MSG_KEXINIT) 788 rekeying = 1; 789 790 packet_send2_wrapped(); 791 792 /* after a NEWKEYS message we can send the complete queue */ 793 if (type == SSH2_MSG_NEWKEYS) { 794 rekeying = 0; 795 while ((p = TAILQ_FIRST(&outgoing))) { 796 type = p->type; 797 debug("dequeue packet: %u", type); 798 buffer_free(&outgoing_packet); 799 memcpy(&outgoing_packet, &p->payload, 800 sizeof(Buffer)); 801 TAILQ_REMOVE(&outgoing, p, next); 802 xfree(p); 803 packet_send2_wrapped(); 804 } 805 } 806 } 807 808 void 809 packet_send(void) 810 { 811 if (compat20) 812 packet_send2(); 813 else 814 packet_send1(); 815 DBG(debug("packet_send done")); 816 } 817 818 /* 819 * Waits until a packet has been received, and returns its type. Note that 820 * no other data is processed until this returns, so this function should not 821 * be used during the interactive session. 822 */ 823 824 int 825 packet_read_seqnr(u_int32_t *seqnr_p) 826 { 827 int type, len; 828 fd_set *setp; 829 char buf[8192]; 830 DBG(debug("packet_read()")); 831 832 setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * 833 sizeof(fd_mask)); 834 835 /* Since we are blocking, ensure that all written packets have been sent. */ 836 packet_write_wait(); 837 838 /* Stay in the loop until we have received a complete packet. */ 839 for (;;) { 840 /* Try to read a packet from the buffer. */ 841 type = packet_read_poll_seqnr(seqnr_p); 842 if (!compat20 && ( 843 type == SSH_SMSG_SUCCESS 844 || type == SSH_SMSG_FAILURE 845 || type == SSH_CMSG_EOF 846 || type == SSH_CMSG_EXIT_CONFIRMATION)) 847 packet_check_eom(); 848 /* If we got a packet, return it. */ 849 if (type != SSH_MSG_NONE) { 850 xfree(setp); 851 return type; 852 } 853 /* 854 * Otherwise, wait for some data to arrive, add it to the 855 * buffer, and try again. 856 */ 857 memset(setp, 0, howmany(connection_in + 1, NFDBITS) * 858 sizeof(fd_mask)); 859 FD_SET(connection_in, setp); 860 861 /* Wait for some data to arrive. */ 862 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && 863 (errno == EAGAIN || errno == EINTR)) 864 ; 865 866 /* Read data from the socket. */ 867 len = read(connection_in, buf, sizeof(buf)); 868 if (len == 0) { 869 logit("Connection closed by %.200s", get_remote_ipaddr()); 870 cleanup_exit(255); 871 } 872 if (len < 0) 873 fatal("Read from socket failed: %.100s", strerror(errno)); 874 /* Append it to the buffer. */ 875 packet_process_incoming(buf, len); 876 } 877 /* NOTREACHED */ 878 } 879 880 int 881 packet_read(void) 882 { 883 return packet_read_seqnr(NULL); 884 } 885 886 /* 887 * Waits until a packet has been received, verifies that its type matches 888 * that given, and gives a fatal error and exits if there is a mismatch. 889 */ 890 891 void 892 packet_read_expect(int expected_type) 893 { 894 int type; 895 896 type = packet_read(); 897 if (type != expected_type) 898 packet_disconnect("Protocol error: expected packet type %d, got %d", 899 expected_type, type); 900 } 901 902 /* Checks if a full packet is available in the data received so far via 903 * packet_process_incoming. If so, reads the packet; otherwise returns 904 * SSH_MSG_NONE. This does not wait for data from the connection. 905 * 906 * SSH_MSG_DISCONNECT is handled specially here. Also, 907 * SSH_MSG_IGNORE messages are skipped by this function and are never returned 908 * to higher levels. 909 */ 910 911 static int 912 packet_read_poll1(void) 913 { 914 u_int len, padded_len; 915 u_char *cp, type; 916 u_int checksum, stored_checksum; 917 918 /* Check if input size is less than minimum packet size. */ 919 if (buffer_len(&input) < 4 + 8) 920 return SSH_MSG_NONE; 921 /* Get length of incoming packet. */ 922 cp = buffer_ptr(&input); 923 len = GET_32BIT(cp); 924 if (len < 1 + 2 + 2 || len > 256 * 1024) 925 packet_disconnect("Bad packet length %u.", len); 926 padded_len = (len + 8) & ~7; 927 928 /* Check if the packet has been entirely received. */ 929 if (buffer_len(&input) < 4 + padded_len) 930 return SSH_MSG_NONE; 931 932 /* The entire packet is in buffer. */ 933 934 /* Consume packet length. */ 935 buffer_consume(&input, 4); 936 937 /* 938 * Cryptographic attack detector for ssh 939 * (C)1998 CORE-SDI, Buenos Aires Argentina 940 * Ariel Futoransky(futo@core-sdi.com) 941 */ 942 if (!receive_context.plaintext && 943 detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) 944 packet_disconnect("crc32 compensation attack: network attack detected"); 945 946 /* Decrypt data to incoming_packet. */ 947 buffer_clear(&incoming_packet); 948 cp = buffer_append_space(&incoming_packet, padded_len); 949 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); 950 951 buffer_consume(&input, padded_len); 952 953 #ifdef PACKET_DEBUG 954 fprintf(stderr, "read_poll plain: "); 955 buffer_dump(&incoming_packet); 956 #endif 957 958 /* Compute packet checksum. */ 959 checksum = ssh_crc32(buffer_ptr(&incoming_packet), 960 buffer_len(&incoming_packet) - 4); 961 962 /* Skip padding. */ 963 buffer_consume(&incoming_packet, 8 - len % 8); 964 965 /* Test check bytes. */ 966 if (len != buffer_len(&incoming_packet)) 967 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", 968 len, buffer_len(&incoming_packet)); 969 970 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; 971 stored_checksum = GET_32BIT(cp); 972 if (checksum != stored_checksum) 973 packet_disconnect("Corrupted check bytes on input."); 974 buffer_consume_end(&incoming_packet, 4); 975 976 if (packet_compression) { 977 buffer_clear(&compression_buffer); 978 buffer_uncompress(&incoming_packet, &compression_buffer); 979 buffer_clear(&incoming_packet); 980 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 981 buffer_len(&compression_buffer)); 982 } 983 type = buffer_get_char(&incoming_packet); 984 return type; 985 } 986 987 static int 988 packet_read_poll2(u_int32_t *seqnr_p) 989 { 990 static u_int packet_length = 0; 991 u_int padlen, need; 992 u_char *macbuf, *cp, type; 993 int maclen, block_size; 994 Enc *enc = NULL; 995 Mac *mac = NULL; 996 Comp *comp = NULL; 997 998 if (newkeys[MODE_IN] != NULL) { 999 enc = &newkeys[MODE_IN]->enc; 1000 mac = &newkeys[MODE_IN]->mac; 1001 comp = &newkeys[MODE_IN]->comp; 1002 } 1003 maclen = mac && mac->enabled ? mac->mac_len : 0; 1004 block_size = enc ? enc->block_size : 8; 1005 1006 if (packet_length == 0) { 1007 /* 1008 * check if input size is less than the cipher block size, 1009 * decrypt first block and extract length of incoming packet 1010 */ 1011 if (buffer_len(&input) < block_size) 1012 return SSH_MSG_NONE; 1013 buffer_clear(&incoming_packet); 1014 cp = buffer_append_space(&incoming_packet, block_size); 1015 cipher_crypt(&receive_context, cp, buffer_ptr(&input), 1016 block_size); 1017 cp = buffer_ptr(&incoming_packet); 1018 packet_length = GET_32BIT(cp); 1019 if (packet_length < 1 + 4 || packet_length > 256 * 1024) { 1020 #ifdef PACKET_DEBUG 1021 buffer_dump(&incoming_packet); 1022 #endif 1023 packet_disconnect("Bad packet length %u.", packet_length); 1024 } 1025 DBG(debug("input: packet len %u", packet_length+4)); 1026 buffer_consume(&input, block_size); 1027 } 1028 /* we have a partial packet of block_size bytes */ 1029 need = 4 + packet_length - block_size; 1030 DBG(debug("partial packet %d, need %d, maclen %d", block_size, 1031 need, maclen)); 1032 if (need % block_size != 0) 1033 fatal("padding error: need %d block %d mod %d", 1034 need, block_size, need % block_size); 1035 /* 1036 * check if the entire packet has been received and 1037 * decrypt into incoming_packet 1038 */ 1039 if (buffer_len(&input) < need + maclen) 1040 return SSH_MSG_NONE; 1041 #ifdef PACKET_DEBUG 1042 fprintf(stderr, "read_poll enc/full: "); 1043 buffer_dump(&input); 1044 #endif 1045 cp = buffer_append_space(&incoming_packet, need); 1046 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); 1047 buffer_consume(&input, need); 1048 /* 1049 * compute MAC over seqnr and packet, 1050 * increment sequence number for incoming packet 1051 */ 1052 if (mac && mac->enabled) { 1053 macbuf = mac_compute(mac, p_read.seqnr, 1054 buffer_ptr(&incoming_packet), 1055 buffer_len(&incoming_packet)); 1056 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) 1057 packet_disconnect("Corrupted MAC on input."); 1058 DBG(debug("MAC #%d ok", p_read.seqnr)); 1059 buffer_consume(&input, mac->mac_len); 1060 } 1061 if (seqnr_p != NULL) 1062 *seqnr_p = p_read.seqnr; 1063 if (++p_read.seqnr == 0) 1064 logit("incoming seqnr wraps around"); 1065 if (++p_read.packets == 0) 1066 if (!(datafellows & SSH_BUG_NOREKEY)) 1067 fatal("XXX too many packets with same key"); 1068 p_read.blocks += (packet_length + 4) / block_size; 1069 1070 /* get padlen */ 1071 cp = buffer_ptr(&incoming_packet); 1072 padlen = cp[4]; 1073 DBG(debug("input: padlen %d", padlen)); 1074 if (padlen < 4) 1075 packet_disconnect("Corrupted padlen %d on input.", padlen); 1076 1077 /* skip packet size + padlen, discard padding */ 1078 buffer_consume(&incoming_packet, 4 + 1); 1079 buffer_consume_end(&incoming_packet, padlen); 1080 1081 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); 1082 if (comp && comp->enabled) { 1083 buffer_clear(&compression_buffer); 1084 buffer_uncompress(&incoming_packet, &compression_buffer); 1085 buffer_clear(&incoming_packet); 1086 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1087 buffer_len(&compression_buffer)); 1088 DBG(debug("input: len after de-compress %d", 1089 buffer_len(&incoming_packet))); 1090 } 1091 /* 1092 * get packet type, implies consume. 1093 * return length of payload (without type field) 1094 */ 1095 type = buffer_get_char(&incoming_packet); 1096 if (type == SSH2_MSG_NEWKEYS) 1097 set_newkeys(MODE_IN); 1098 #ifdef PACKET_DEBUG 1099 fprintf(stderr, "read/plain[%d]:\r\n", type); 1100 buffer_dump(&incoming_packet); 1101 #endif 1102 /* reset for next packet */ 1103 packet_length = 0; 1104 return type; 1105 } 1106 1107 int 1108 packet_read_poll_seqnr(u_int32_t *seqnr_p) 1109 { 1110 u_int reason, seqnr; 1111 u_char type; 1112 char *msg; 1113 1114 for (;;) { 1115 if (compat20) { 1116 type = packet_read_poll2(seqnr_p); 1117 if (type) 1118 DBG(debug("received packet type %d", type)); 1119 switch (type) { 1120 case SSH2_MSG_IGNORE: 1121 break; 1122 case SSH2_MSG_DEBUG: 1123 packet_get_char(); 1124 msg = packet_get_string(NULL); 1125 debug("Remote: %.900s", msg); 1126 xfree(msg); 1127 msg = packet_get_string(NULL); 1128 xfree(msg); 1129 break; 1130 case SSH2_MSG_DISCONNECT: 1131 reason = packet_get_int(); 1132 msg = packet_get_string(NULL); 1133 logit("Received disconnect from %s: %u: %.400s", 1134 get_remote_ipaddr(), reason, msg); 1135 xfree(msg); 1136 cleanup_exit(255); 1137 break; 1138 case SSH2_MSG_UNIMPLEMENTED: 1139 seqnr = packet_get_int(); 1140 debug("Received SSH2_MSG_UNIMPLEMENTED for %u", 1141 seqnr); 1142 break; 1143 default: 1144 return type; 1145 break; 1146 } 1147 } else { 1148 type = packet_read_poll1(); 1149 switch (type) { 1150 case SSH_MSG_IGNORE: 1151 break; 1152 case SSH_MSG_DEBUG: 1153 msg = packet_get_string(NULL); 1154 debug("Remote: %.900s", msg); 1155 xfree(msg); 1156 break; 1157 case SSH_MSG_DISCONNECT: 1158 msg = packet_get_string(NULL); 1159 logit("Received disconnect from %s: %.400s", 1160 get_remote_ipaddr(), msg); 1161 cleanup_exit(255); 1162 xfree(msg); 1163 break; 1164 default: 1165 if (type) 1166 DBG(debug("received packet type %d", type)); 1167 return type; 1168 break; 1169 } 1170 } 1171 } 1172 } 1173 1174 int 1175 packet_read_poll(void) 1176 { 1177 return packet_read_poll_seqnr(NULL); 1178 } 1179 1180 /* 1181 * Buffers the given amount of input characters. This is intended to be used 1182 * together with packet_read_poll. 1183 */ 1184 1185 void 1186 packet_process_incoming(const char *buf, u_int len) 1187 { 1188 buffer_append(&input, buf, len); 1189 } 1190 1191 /* Returns a character from the packet. */ 1192 1193 u_int 1194 packet_get_char(void) 1195 { 1196 char ch; 1197 1198 buffer_get(&incoming_packet, &ch, 1); 1199 return (u_char) ch; 1200 } 1201 1202 /* Returns an integer from the packet data. */ 1203 1204 u_int 1205 packet_get_int(void) 1206 { 1207 return buffer_get_int(&incoming_packet); 1208 } 1209 1210 /* 1211 * Returns an arbitrary precision integer from the packet data. The integer 1212 * must have been initialized before this call. 1213 */ 1214 1215 void 1216 packet_get_bignum(BIGNUM * value) 1217 { 1218 buffer_get_bignum(&incoming_packet, value); 1219 } 1220 1221 void 1222 packet_get_bignum2(BIGNUM * value) 1223 { 1224 buffer_get_bignum2(&incoming_packet, value); 1225 } 1226 1227 void * 1228 packet_get_raw(int *length_ptr) 1229 { 1230 int bytes = buffer_len(&incoming_packet); 1231 1232 if (length_ptr != NULL) 1233 *length_ptr = bytes; 1234 return buffer_ptr(&incoming_packet); 1235 } 1236 1237 int 1238 packet_remaining(void) 1239 { 1240 return buffer_len(&incoming_packet); 1241 } 1242 1243 /* 1244 * Returns a string from the packet data. The string is allocated using 1245 * xmalloc; it is the responsibility of the calling program to free it when 1246 * no longer needed. The length_ptr argument may be NULL, or point to an 1247 * integer into which the length of the string is stored. 1248 */ 1249 1250 void * 1251 packet_get_string(u_int *length_ptr) 1252 { 1253 return buffer_get_string(&incoming_packet, length_ptr); 1254 } 1255 1256 /* 1257 * Sends a diagnostic message from the server to the client. This message 1258 * can be sent at any time (but not while constructing another message). The 1259 * message is printed immediately, but only if the client is being executed 1260 * in verbose mode. These messages are primarily intended to ease debugging 1261 * authentication problems. The length of the formatted message must not 1262 * exceed 1024 bytes. This will automatically call packet_write_wait. 1263 */ 1264 1265 void 1266 packet_send_debug(const char *fmt,...) 1267 { 1268 char buf[1024]; 1269 va_list args; 1270 1271 if (compat20 && (datafellows & SSH_BUG_DEBUG)) 1272 return; 1273 1274 va_start(args, fmt); 1275 vsnprintf(buf, sizeof(buf), fmt, args); 1276 va_end(args); 1277 1278 if (compat20) { 1279 packet_start(SSH2_MSG_DEBUG); 1280 packet_put_char(0); /* bool: always display */ 1281 packet_put_cstring(buf); 1282 packet_put_cstring(""); 1283 } else { 1284 packet_start(SSH_MSG_DEBUG); 1285 packet_put_cstring(buf); 1286 } 1287 packet_send(); 1288 packet_write_wait(); 1289 } 1290 1291 /* 1292 * Logs the error plus constructs and sends a disconnect packet, closes the 1293 * connection, and exits. This function never returns. The error message 1294 * should not contain a newline. The length of the formatted message must 1295 * not exceed 1024 bytes. 1296 */ 1297 1298 void 1299 packet_disconnect(const char *fmt,...) 1300 { 1301 char buf[1024]; 1302 va_list args; 1303 static int disconnecting = 0; 1304 1305 if (disconnecting) /* Guard against recursive invocations. */ 1306 fatal("packet_disconnect called recursively."); 1307 disconnecting = 1; 1308 1309 /* 1310 * Format the message. Note that the caller must make sure the 1311 * message is of limited size. 1312 */ 1313 va_start(args, fmt); 1314 vsnprintf(buf, sizeof(buf), fmt, args); 1315 va_end(args); 1316 1317 /* Display the error locally */ 1318 logit("Disconnecting: %.100s", buf); 1319 1320 /* Send the disconnect message to the other side, and wait for it to get sent. */ 1321 if (compat20) { 1322 packet_start(SSH2_MSG_DISCONNECT); 1323 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); 1324 packet_put_cstring(buf); 1325 packet_put_cstring(""); 1326 } else { 1327 packet_start(SSH_MSG_DISCONNECT); 1328 packet_put_cstring(buf); 1329 } 1330 packet_send(); 1331 packet_write_wait(); 1332 1333 /* Stop listening for connections. */ 1334 channel_close_all(); 1335 1336 /* Close the connection. */ 1337 packet_close(); 1338 cleanup_exit(255); 1339 } 1340 1341 /* Checks if there is any buffered output, and tries to write some of the output. */ 1342 1343 void 1344 packet_write_poll(void) 1345 { 1346 int len = buffer_len(&output); 1347 1348 if (len > 0) { 1349 len = write(connection_out, buffer_ptr(&output), len); 1350 if (len <= 0) { 1351 if (errno == EAGAIN) 1352 return; 1353 else 1354 fatal("Write failed: %.100s", strerror(errno)); 1355 } 1356 buffer_consume(&output, len); 1357 } 1358 } 1359 1360 /* 1361 * Calls packet_write_poll repeatedly until all pending output data has been 1362 * written. 1363 */ 1364 1365 void 1366 packet_write_wait(void) 1367 { 1368 fd_set *setp; 1369 1370 setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * 1371 sizeof(fd_mask)); 1372 packet_write_poll(); 1373 while (packet_have_data_to_write()) { 1374 memset(setp, 0, howmany(connection_out + 1, NFDBITS) * 1375 sizeof(fd_mask)); 1376 FD_SET(connection_out, setp); 1377 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && 1378 (errno == EAGAIN || errno == EINTR)) 1379 ; 1380 packet_write_poll(); 1381 } 1382 xfree(setp); 1383 } 1384 1385 /* Returns true if there is buffered data to write to the connection. */ 1386 1387 int 1388 packet_have_data_to_write(void) 1389 { 1390 return buffer_len(&output) != 0; 1391 } 1392 1393 /* Returns true if there is not too much data to write to the connection. */ 1394 1395 int 1396 packet_not_very_much_data_to_write(void) 1397 { 1398 if (interactive_mode) 1399 return buffer_len(&output) < 16384; 1400 else 1401 return buffer_len(&output) < 128 * 1024; 1402 } 1403 1404 1405 static void 1406 packet_set_tos(int interactive) 1407 { 1408 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) 1409 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; 1410 1411 if (!packet_connection_is_on_socket() || 1412 !packet_connection_is_ipv4()) 1413 return; 1414 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, 1415 sizeof(tos)) < 0) 1416 error("setsockopt IP_TOS %d: %.100s:", 1417 tos, strerror(errno)); 1418 #endif 1419 } 1420 1421 /* Informs that the current session is interactive. Sets IP flags for that. */ 1422 1423 void 1424 packet_set_interactive(int interactive) 1425 { 1426 static int called = 0; 1427 1428 if (called) 1429 return; 1430 called = 1; 1431 1432 /* Record that we are in interactive mode. */ 1433 interactive_mode = interactive; 1434 1435 /* Only set socket options if using a socket. */ 1436 if (!packet_connection_is_on_socket()) 1437 return; 1438 if (interactive) 1439 set_nodelay(connection_in); 1440 packet_set_tos(interactive); 1441 } 1442 1443 /* Returns true if the current connection is interactive. */ 1444 1445 int 1446 packet_is_interactive(void) 1447 { 1448 return interactive_mode; 1449 } 1450 1451 int 1452 packet_set_maxsize(u_int s) 1453 { 1454 static int called = 0; 1455 1456 if (called) { 1457 logit("packet_set_maxsize: called twice: old %d new %d", 1458 max_packet_size, s); 1459 return -1; 1460 } 1461 if (s < 4 * 1024 || s > 1024 * 1024) { 1462 logit("packet_set_maxsize: bad size %d", s); 1463 return -1; 1464 } 1465 called = 1; 1466 debug("packet_set_maxsize: setting to %d", s); 1467 max_packet_size = s; 1468 return s; 1469 } 1470 1471 /* roundup current message to pad bytes */ 1472 void 1473 packet_add_padding(u_char pad) 1474 { 1475 extra_pad = pad; 1476 } 1477 1478 /* 1479 * 9.2. Ignored Data Message 1480 * 1481 * byte SSH_MSG_IGNORE 1482 * string data 1483 * 1484 * All implementations MUST understand (and ignore) this message at any 1485 * time (after receiving the protocol version). No implementation is 1486 * required to send them. This message can be used as an additional 1487 * protection measure against advanced traffic analysis techniques. 1488 */ 1489 void 1490 packet_send_ignore(int nbytes) 1491 { 1492 u_int32_t rnd = 0; 1493 int i; 1494 1495 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); 1496 packet_put_int(nbytes); 1497 for (i = 0; i < nbytes; i++) { 1498 if (i % 4 == 0) 1499 rnd = arc4random(); 1500 packet_put_char(rnd & 0xff); 1501 rnd >>= 8; 1502 } 1503 } 1504 1505 #define MAX_PACKETS (1U<<31) 1506 int 1507 packet_need_rekeying(void) 1508 { 1509 if (datafellows & SSH_BUG_NOREKEY) 1510 return 0; 1511 return 1512 (p_send.packets > MAX_PACKETS) || 1513 (p_read.packets > MAX_PACKETS) || 1514 (max_blocks_out && (p_send.blocks > max_blocks_out)) || 1515 (max_blocks_in && (p_read.blocks > max_blocks_in)); 1516 } 1517 1518 void 1519 packet_set_rekey_limit(u_int32_t bytes) 1520 { 1521 rekey_limit = bytes; 1522 } 1523