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 1.112 2003/09/23 20:17:11 markus Exp $"); 41 42 #include <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, "", 0, NULL, 0, CIPHER_ENCRYPT); 158 cipher_init(&receive_context, none, "", 0, NULL, 0, CIPHER_DECRYPT); 159 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; 160 if (!initialized) { 161 initialized = 1; 162 buffer_init(&input); 163 buffer_init(&output); 164 buffer_init(&outgoing_packet); 165 buffer_init(&incoming_packet); 166 TAILQ_INIT(&outgoing); 167 } 168 } 169 170 /* Returns 1 if remote host is connected via socket, 0 if not. */ 171 172 int 173 packet_connection_is_on_socket(void) 174 { 175 struct sockaddr_storage from, to; 176 socklen_t fromlen, tolen; 177 178 /* filedescriptors in and out are the same, so it's a socket */ 179 if (connection_in == connection_out) 180 return 1; 181 fromlen = sizeof(from); 182 memset(&from, 0, sizeof(from)); 183 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) 184 return 0; 185 tolen = sizeof(to); 186 memset(&to, 0, sizeof(to)); 187 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) 188 return 0; 189 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) 190 return 0; 191 if (from.ss_family != AF_INET && from.ss_family != AF_INET6) 192 return 0; 193 return 1; 194 } 195 196 /* 197 * Exports an IV from the CipherContext required to export the key 198 * state back from the unprivileged child to the privileged parent 199 * process. 200 */ 201 202 void 203 packet_get_keyiv(int mode, u_char *iv, u_int len) 204 { 205 CipherContext *cc; 206 207 if (mode == MODE_OUT) 208 cc = &send_context; 209 else 210 cc = &receive_context; 211 212 cipher_get_keyiv(cc, iv, len); 213 } 214 215 int 216 packet_get_keycontext(int mode, u_char *dat) 217 { 218 CipherContext *cc; 219 220 if (mode == MODE_OUT) 221 cc = &send_context; 222 else 223 cc = &receive_context; 224 225 return (cipher_get_keycontext(cc, dat)); 226 } 227 228 void 229 packet_set_keycontext(int mode, u_char *dat) 230 { 231 CipherContext *cc; 232 233 if (mode == MODE_OUT) 234 cc = &send_context; 235 else 236 cc = &receive_context; 237 238 cipher_set_keycontext(cc, dat); 239 } 240 241 int 242 packet_get_keyiv_len(int mode) 243 { 244 CipherContext *cc; 245 246 if (mode == MODE_OUT) 247 cc = &send_context; 248 else 249 cc = &receive_context; 250 251 return (cipher_get_keyiv_len(cc)); 252 } 253 void 254 packet_set_iv(int mode, u_char *dat) 255 { 256 CipherContext *cc; 257 258 if (mode == MODE_OUT) 259 cc = &send_context; 260 else 261 cc = &receive_context; 262 263 cipher_set_keyiv(cc, dat); 264 } 265 int 266 packet_get_ssh1_cipher(void) 267 { 268 return (cipher_get_number(receive_context.cipher)); 269 } 270 271 void 272 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets) 273 { 274 struct packet_state *state; 275 276 state = (mode == MODE_IN) ? &p_read : &p_send; 277 *seqnr = state->seqnr; 278 *blocks = state->blocks; 279 *packets = state->packets; 280 } 281 282 void 283 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets) 284 { 285 struct packet_state *state; 286 287 state = (mode == MODE_IN) ? &p_read : &p_send; 288 state->seqnr = seqnr; 289 state->blocks = blocks; 290 state->packets = packets; 291 } 292 293 /* returns 1 if connection is via ipv4 */ 294 295 int 296 packet_connection_is_ipv4(void) 297 { 298 struct sockaddr_storage to; 299 socklen_t tolen = sizeof(to); 300 301 memset(&to, 0, sizeof(to)); 302 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) 303 return 0; 304 if (to.ss_family != AF_INET) 305 return 0; 306 return 1; 307 } 308 309 /* Sets the connection into non-blocking mode. */ 310 311 void 312 packet_set_nonblocking(void) 313 { 314 /* Set the socket into non-blocking mode. */ 315 if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) 316 error("fcntl O_NONBLOCK: %.100s", strerror(errno)); 317 318 if (connection_out != connection_in) { 319 if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0) 320 error("fcntl O_NONBLOCK: %.100s", strerror(errno)); 321 } 322 } 323 324 /* Returns the socket used for reading. */ 325 326 int 327 packet_get_connection_in(void) 328 { 329 return connection_in; 330 } 331 332 /* Returns the descriptor used for writing. */ 333 334 int 335 packet_get_connection_out(void) 336 { 337 return connection_out; 338 } 339 340 /* Closes the connection and clears and frees internal data structures. */ 341 342 void 343 packet_close(void) 344 { 345 if (!initialized) 346 return; 347 initialized = 0; 348 if (connection_in == connection_out) { 349 shutdown(connection_out, SHUT_RDWR); 350 close(connection_out); 351 } else { 352 close(connection_in); 353 close(connection_out); 354 } 355 buffer_free(&input); 356 buffer_free(&output); 357 buffer_free(&outgoing_packet); 358 buffer_free(&incoming_packet); 359 if (compression_buffer_ready) { 360 buffer_free(&compression_buffer); 361 buffer_compress_uninit(); 362 } 363 cipher_cleanup(&send_context); 364 cipher_cleanup(&receive_context); 365 } 366 367 /* Sets remote side protocol flags. */ 368 369 void 370 packet_set_protocol_flags(u_int protocol_flags) 371 { 372 remote_protocol_flags = protocol_flags; 373 } 374 375 /* Returns the remote protocol flags set earlier by the above function. */ 376 377 u_int 378 packet_get_protocol_flags(void) 379 { 380 return remote_protocol_flags; 381 } 382 383 /* 384 * Starts packet compression from the next packet on in both directions. 385 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. 386 */ 387 388 static void 389 packet_init_compression(void) 390 { 391 if (compression_buffer_ready == 1) 392 return; 393 compression_buffer_ready = 1; 394 buffer_init(&compression_buffer); 395 } 396 397 void 398 packet_start_compression(int level) 399 { 400 if (packet_compression && !compat20) 401 fatal("Compression already enabled."); 402 packet_compression = 1; 403 packet_init_compression(); 404 buffer_compress_init_send(level); 405 buffer_compress_init_recv(); 406 } 407 408 /* 409 * Causes any further packets to be encrypted using the given key. The same 410 * key is used for both sending and reception. However, both directions are 411 * encrypted independently of each other. 412 */ 413 414 void 415 packet_set_encryption_key(const u_char *key, u_int keylen, 416 int number) 417 { 418 Cipher *cipher = cipher_by_number(number); 419 420 if (cipher == NULL) 421 fatal("packet_set_encryption_key: unknown cipher number %d", number); 422 if (keylen < 20) 423 fatal("packet_set_encryption_key: keylen too small: %d", keylen); 424 if (keylen > SSH_SESSION_KEY_LENGTH) 425 fatal("packet_set_encryption_key: keylen too big: %d", keylen); 426 memcpy(ssh1_key, key, keylen); 427 ssh1_keylen = keylen; 428 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); 429 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); 430 } 431 432 u_int 433 packet_get_encryption_key(u_char *key) 434 { 435 if (key == NULL) 436 return (ssh1_keylen); 437 memcpy(key, ssh1_key, ssh1_keylen); 438 return (ssh1_keylen); 439 } 440 441 /* Start constructing a packet to send. */ 442 void 443 packet_start(u_char type) 444 { 445 u_char buf[9]; 446 int len; 447 448 DBG(debug("packet_start[%d]", type)); 449 len = compat20 ? 6 : 9; 450 memset(buf, 0, len - 1); 451 buf[len - 1] = type; 452 buffer_clear(&outgoing_packet); 453 buffer_append(&outgoing_packet, buf, len); 454 } 455 456 /* Append payload. */ 457 void 458 packet_put_char(int value) 459 { 460 char ch = value; 461 462 buffer_append(&outgoing_packet, &ch, 1); 463 } 464 void 465 packet_put_int(u_int value) 466 { 467 buffer_put_int(&outgoing_packet, value); 468 } 469 void 470 packet_put_string(const void *buf, u_int len) 471 { 472 buffer_put_string(&outgoing_packet, buf, len); 473 } 474 void 475 packet_put_cstring(const char *str) 476 { 477 buffer_put_cstring(&outgoing_packet, str); 478 } 479 void 480 packet_put_raw(const void *buf, u_int len) 481 { 482 buffer_append(&outgoing_packet, buf, len); 483 } 484 void 485 packet_put_bignum(BIGNUM * value) 486 { 487 buffer_put_bignum(&outgoing_packet, value); 488 } 489 void 490 packet_put_bignum2(BIGNUM * value) 491 { 492 buffer_put_bignum2(&outgoing_packet, value); 493 } 494 495 /* 496 * Finalizes and sends the packet. If the encryption key has been set, 497 * encrypts the packet before sending. 498 */ 499 500 static void 501 packet_send1(void) 502 { 503 u_char buf[8], *cp; 504 int i, padding, len; 505 u_int checksum; 506 u_int32_t rand = 0; 507 508 /* 509 * If using packet compression, compress the payload of the outgoing 510 * packet. 511 */ 512 if (packet_compression) { 513 buffer_clear(&compression_buffer); 514 /* Skip padding. */ 515 buffer_consume(&outgoing_packet, 8); 516 /* padding */ 517 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); 518 buffer_compress(&outgoing_packet, &compression_buffer); 519 buffer_clear(&outgoing_packet); 520 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 521 buffer_len(&compression_buffer)); 522 } 523 /* Compute packet length without padding (add checksum, remove padding). */ 524 len = buffer_len(&outgoing_packet) + 4 - 8; 525 526 /* Insert padding. Initialized to zero in packet_start1() */ 527 padding = 8 - len % 8; 528 if (!send_context.plaintext) { 529 cp = buffer_ptr(&outgoing_packet); 530 for (i = 0; i < padding; i++) { 531 if (i % 4 == 0) 532 rand = arc4random(); 533 cp[7 - i] = rand & 0xff; 534 rand >>= 8; 535 } 536 } 537 buffer_consume(&outgoing_packet, 8 - padding); 538 539 /* Add check bytes. */ 540 checksum = ssh_crc32(buffer_ptr(&outgoing_packet), 541 buffer_len(&outgoing_packet)); 542 PUT_32BIT(buf, checksum); 543 buffer_append(&outgoing_packet, buf, 4); 544 545 #ifdef PACKET_DEBUG 546 fprintf(stderr, "packet_send plain: "); 547 buffer_dump(&outgoing_packet); 548 #endif 549 550 /* Append to output. */ 551 PUT_32BIT(buf, len); 552 buffer_append(&output, buf, 4); 553 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 554 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 555 buffer_len(&outgoing_packet)); 556 557 #ifdef PACKET_DEBUG 558 fprintf(stderr, "encrypted: "); 559 buffer_dump(&output); 560 #endif 561 562 buffer_clear(&outgoing_packet); 563 564 /* 565 * Note that the packet is now only buffered in output. It won\'t be 566 * actually sent until packet_write_wait or packet_write_poll is 567 * called. 568 */ 569 } 570 571 void 572 set_newkeys(int mode) 573 { 574 Enc *enc; 575 Mac *mac; 576 Comp *comp; 577 CipherContext *cc; 578 u_int64_t *max_blocks; 579 int encrypt; 580 581 debug2("set_newkeys: mode %d", mode); 582 583 if (mode == MODE_OUT) { 584 cc = &send_context; 585 encrypt = CIPHER_ENCRYPT; 586 p_send.packets = p_send.blocks = 0; 587 max_blocks = &max_blocks_out; 588 } else { 589 cc = &receive_context; 590 encrypt = CIPHER_DECRYPT; 591 p_read.packets = p_read.blocks = 0; 592 max_blocks = &max_blocks_in; 593 } 594 if (newkeys[mode] != NULL) { 595 debug("set_newkeys: rekeying"); 596 cipher_cleanup(cc); 597 enc = &newkeys[mode]->enc; 598 mac = &newkeys[mode]->mac; 599 comp = &newkeys[mode]->comp; 600 memset(mac->key, 0, mac->key_len); 601 xfree(enc->name); 602 xfree(enc->iv); 603 xfree(enc->key); 604 xfree(mac->name); 605 xfree(mac->key); 606 xfree(comp->name); 607 xfree(newkeys[mode]); 608 } 609 newkeys[mode] = kex_get_newkeys(mode); 610 if (newkeys[mode] == NULL) 611 fatal("newkeys: no keys for mode %d", mode); 612 enc = &newkeys[mode]->enc; 613 mac = &newkeys[mode]->mac; 614 comp = &newkeys[mode]->comp; 615 if (mac->md != NULL) 616 mac->enabled = 1; 617 DBG(debug("cipher_init_context: %d", mode)); 618 cipher_init(cc, enc->cipher, enc->key, enc->key_len, 619 enc->iv, enc->block_size, encrypt); 620 /* Deleting the keys does not gain extra security */ 621 /* memset(enc->iv, 0, enc->block_size); 622 memset(enc->key, 0, enc->key_len); */ 623 if (comp->type != 0 && comp->enabled == 0) { 624 packet_init_compression(); 625 if (mode == MODE_OUT) 626 buffer_compress_init_send(6); 627 else 628 buffer_compress_init_recv(); 629 comp->enabled = 1; 630 } 631 /* 632 * The 2^(blocksize*2) limit is too expensive for 3DES, 633 * blowfish, etc, so enforce a 1GB limit for small blocksizes. 634 */ 635 if (enc->block_size >= 16) 636 *max_blocks = (u_int64_t)1 << (enc->block_size*2); 637 else 638 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; 639 if (rekey_limit) 640 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); 641 } 642 643 /* 644 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) 645 */ 646 static void 647 packet_send2_wrapped(void) 648 { 649 u_char type, *cp, *macbuf = NULL; 650 u_char padlen, pad; 651 u_int packet_length = 0; 652 u_int i, len; 653 u_int32_t rand = 0; 654 Enc *enc = NULL; 655 Mac *mac = NULL; 656 Comp *comp = NULL; 657 int block_size; 658 659 if (newkeys[MODE_OUT] != NULL) { 660 enc = &newkeys[MODE_OUT]->enc; 661 mac = &newkeys[MODE_OUT]->mac; 662 comp = &newkeys[MODE_OUT]->comp; 663 } 664 block_size = enc ? enc->block_size : 8; 665 666 cp = buffer_ptr(&outgoing_packet); 667 type = cp[5]; 668 669 #ifdef PACKET_DEBUG 670 fprintf(stderr, "plain: "); 671 buffer_dump(&outgoing_packet); 672 #endif 673 674 if (comp && comp->enabled) { 675 len = buffer_len(&outgoing_packet); 676 /* skip header, compress only payload */ 677 buffer_consume(&outgoing_packet, 5); 678 buffer_clear(&compression_buffer); 679 buffer_compress(&outgoing_packet, &compression_buffer); 680 buffer_clear(&outgoing_packet); 681 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); 682 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 683 buffer_len(&compression_buffer)); 684 DBG(debug("compression: raw %d compressed %d", len, 685 buffer_len(&outgoing_packet))); 686 } 687 688 /* sizeof (packet_len + pad_len + payload) */ 689 len = buffer_len(&outgoing_packet); 690 691 /* 692 * calc size of padding, alloc space, get random data, 693 * minimum padding is 4 bytes 694 */ 695 padlen = block_size - (len % block_size); 696 if (padlen < 4) 697 padlen += block_size; 698 if (extra_pad) { 699 /* will wrap if extra_pad+padlen > 255 */ 700 extra_pad = roundup(extra_pad, block_size); 701 pad = extra_pad - ((len + padlen) % extra_pad); 702 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", 703 pad, len, padlen, extra_pad); 704 padlen += pad; 705 extra_pad = 0; 706 } 707 cp = buffer_append_space(&outgoing_packet, padlen); 708 if (enc && !send_context.plaintext) { 709 /* random padding */ 710 for (i = 0; i < padlen; i++) { 711 if (i % 4 == 0) 712 rand = arc4random(); 713 cp[i] = rand & 0xff; 714 rand >>= 8; 715 } 716 } else { 717 /* clear padding */ 718 memset(cp, 0, padlen); 719 } 720 /* packet_length includes payload, padding and padding length field */ 721 packet_length = buffer_len(&outgoing_packet) - 4; 722 cp = buffer_ptr(&outgoing_packet); 723 PUT_32BIT(cp, packet_length); 724 cp[4] = padlen; 725 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); 726 727 /* compute MAC over seqnr and packet(length fields, payload, padding) */ 728 if (mac && mac->enabled) { 729 macbuf = mac_compute(mac, p_send.seqnr, 730 buffer_ptr(&outgoing_packet), 731 buffer_len(&outgoing_packet)); 732 DBG(debug("done calc MAC out #%d", p_send.seqnr)); 733 } 734 /* encrypt packet and append to output buffer. */ 735 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 736 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 737 buffer_len(&outgoing_packet)); 738 /* append unencrypted MAC */ 739 if (mac && mac->enabled) 740 buffer_append(&output, (char *)macbuf, mac->mac_len); 741 #ifdef PACKET_DEBUG 742 fprintf(stderr, "encrypted: "); 743 buffer_dump(&output); 744 #endif 745 /* increment sequence number for outgoing packets */ 746 if (++p_send.seqnr == 0) 747 logit("outgoing seqnr wraps around"); 748 if (++p_send.packets == 0) 749 if (!(datafellows & SSH_BUG_NOREKEY)) 750 fatal("XXX too many packets with same key"); 751 p_send.blocks += (packet_length + 4) / block_size; 752 buffer_clear(&outgoing_packet); 753 754 if (type == SSH2_MSG_NEWKEYS) 755 set_newkeys(MODE_OUT); 756 } 757 758 static void 759 packet_send2(void) 760 { 761 static int rekeying = 0; 762 struct packet *p; 763 u_char type, *cp; 764 765 cp = buffer_ptr(&outgoing_packet); 766 type = cp[5]; 767 768 /* during rekeying we can only send key exchange messages */ 769 if (rekeying) { 770 if (!((type >= SSH2_MSG_TRANSPORT_MIN) && 771 (type <= SSH2_MSG_TRANSPORT_MAX))) { 772 debug("enqueue packet: %u", type); 773 p = xmalloc(sizeof(*p)); 774 p->type = type; 775 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); 776 buffer_init(&outgoing_packet); 777 TAILQ_INSERT_TAIL(&outgoing, p, next); 778 return; 779 } 780 } 781 782 /* rekeying starts with sending KEXINIT */ 783 if (type == SSH2_MSG_KEXINIT) 784 rekeying = 1; 785 786 packet_send2_wrapped(); 787 788 /* after a NEWKEYS message we can send the complete queue */ 789 if (type == SSH2_MSG_NEWKEYS) { 790 rekeying = 0; 791 while ((p = TAILQ_FIRST(&outgoing))) { 792 type = p->type; 793 debug("dequeue packet: %u", type); 794 buffer_free(&outgoing_packet); 795 memcpy(&outgoing_packet, &p->payload, 796 sizeof(Buffer)); 797 TAILQ_REMOVE(&outgoing, p, next); 798 xfree(p); 799 packet_send2_wrapped(); 800 } 801 } 802 } 803 804 void 805 packet_send(void) 806 { 807 if (compat20) 808 packet_send2(); 809 else 810 packet_send1(); 811 DBG(debug("packet_send done")); 812 } 813 814 /* 815 * Waits until a packet has been received, and returns its type. Note that 816 * no other data is processed until this returns, so this function should not 817 * be used during the interactive session. 818 */ 819 820 int 821 packet_read_seqnr(u_int32_t *seqnr_p) 822 { 823 int type, len; 824 fd_set *setp; 825 char buf[8192]; 826 DBG(debug("packet_read()")); 827 828 setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * 829 sizeof(fd_mask)); 830 831 /* Since we are blocking, ensure that all written packets have been sent. */ 832 packet_write_wait(); 833 834 /* Stay in the loop until we have received a complete packet. */ 835 for (;;) { 836 /* Try to read a packet from the buffer. */ 837 type = packet_read_poll_seqnr(seqnr_p); 838 if (!compat20 && ( 839 type == SSH_SMSG_SUCCESS 840 || type == SSH_SMSG_FAILURE 841 || type == SSH_CMSG_EOF 842 || type == SSH_CMSG_EXIT_CONFIRMATION)) 843 packet_check_eom(); 844 /* If we got a packet, return it. */ 845 if (type != SSH_MSG_NONE) { 846 xfree(setp); 847 return type; 848 } 849 /* 850 * Otherwise, wait for some data to arrive, add it to the 851 * buffer, and try again. 852 */ 853 memset(setp, 0, howmany(connection_in + 1, NFDBITS) * 854 sizeof(fd_mask)); 855 FD_SET(connection_in, setp); 856 857 /* Wait for some data to arrive. */ 858 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && 859 (errno == EAGAIN || errno == EINTR)) 860 ; 861 862 /* Read data from the socket. */ 863 len = read(connection_in, buf, sizeof(buf)); 864 if (len == 0) { 865 logit("Connection closed by %.200s", get_remote_ipaddr()); 866 cleanup_exit(255); 867 } 868 if (len < 0) 869 fatal("Read from socket failed: %.100s", strerror(errno)); 870 /* Append it to the buffer. */ 871 packet_process_incoming(buf, len); 872 } 873 /* NOTREACHED */ 874 } 875 876 int 877 packet_read(void) 878 { 879 return packet_read_seqnr(NULL); 880 } 881 882 /* 883 * Waits until a packet has been received, verifies that its type matches 884 * that given, and gives a fatal error and exits if there is a mismatch. 885 */ 886 887 void 888 packet_read_expect(int expected_type) 889 { 890 int type; 891 892 type = packet_read(); 893 if (type != expected_type) 894 packet_disconnect("Protocol error: expected packet type %d, got %d", 895 expected_type, type); 896 } 897 898 /* Checks if a full packet is available in the data received so far via 899 * packet_process_incoming. If so, reads the packet; otherwise returns 900 * SSH_MSG_NONE. This does not wait for data from the connection. 901 * 902 * SSH_MSG_DISCONNECT is handled specially here. Also, 903 * SSH_MSG_IGNORE messages are skipped by this function and are never returned 904 * to higher levels. 905 */ 906 907 static int 908 packet_read_poll1(void) 909 { 910 u_int len, padded_len; 911 u_char *cp, type; 912 u_int checksum, stored_checksum; 913 914 /* Check if input size is less than minimum packet size. */ 915 if (buffer_len(&input) < 4 + 8) 916 return SSH_MSG_NONE; 917 /* Get length of incoming packet. */ 918 cp = buffer_ptr(&input); 919 len = GET_32BIT(cp); 920 if (len < 1 + 2 + 2 || len > 256 * 1024) 921 packet_disconnect("Bad packet length %u.", len); 922 padded_len = (len + 8) & ~7; 923 924 /* Check if the packet has been entirely received. */ 925 if (buffer_len(&input) < 4 + padded_len) 926 return SSH_MSG_NONE; 927 928 /* The entire packet is in buffer. */ 929 930 /* Consume packet length. */ 931 buffer_consume(&input, 4); 932 933 /* 934 * Cryptographic attack detector for ssh 935 * (C)1998 CORE-SDI, Buenos Aires Argentina 936 * Ariel Futoransky(futo@core-sdi.com) 937 */ 938 if (!receive_context.plaintext && 939 detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) 940 packet_disconnect("crc32 compensation attack: network attack detected"); 941 942 /* Decrypt data to incoming_packet. */ 943 buffer_clear(&incoming_packet); 944 cp = buffer_append_space(&incoming_packet, padded_len); 945 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); 946 947 buffer_consume(&input, padded_len); 948 949 #ifdef PACKET_DEBUG 950 fprintf(stderr, "read_poll plain: "); 951 buffer_dump(&incoming_packet); 952 #endif 953 954 /* Compute packet checksum. */ 955 checksum = ssh_crc32(buffer_ptr(&incoming_packet), 956 buffer_len(&incoming_packet) - 4); 957 958 /* Skip padding. */ 959 buffer_consume(&incoming_packet, 8 - len % 8); 960 961 /* Test check bytes. */ 962 if (len != buffer_len(&incoming_packet)) 963 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", 964 len, buffer_len(&incoming_packet)); 965 966 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; 967 stored_checksum = GET_32BIT(cp); 968 if (checksum != stored_checksum) 969 packet_disconnect("Corrupted check bytes on input."); 970 buffer_consume_end(&incoming_packet, 4); 971 972 if (packet_compression) { 973 buffer_clear(&compression_buffer); 974 buffer_uncompress(&incoming_packet, &compression_buffer); 975 buffer_clear(&incoming_packet); 976 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 977 buffer_len(&compression_buffer)); 978 } 979 type = buffer_get_char(&incoming_packet); 980 return type; 981 } 982 983 static int 984 packet_read_poll2(u_int32_t *seqnr_p) 985 { 986 static u_int packet_length = 0; 987 u_int padlen, need; 988 u_char *macbuf, *cp, type; 989 int maclen, block_size; 990 Enc *enc = NULL; 991 Mac *mac = NULL; 992 Comp *comp = NULL; 993 994 if (newkeys[MODE_IN] != NULL) { 995 enc = &newkeys[MODE_IN]->enc; 996 mac = &newkeys[MODE_IN]->mac; 997 comp = &newkeys[MODE_IN]->comp; 998 } 999 maclen = mac && mac->enabled ? mac->mac_len : 0; 1000 block_size = enc ? enc->block_size : 8; 1001 1002 if (packet_length == 0) { 1003 /* 1004 * check if input size is less than the cipher block size, 1005 * decrypt first block and extract length of incoming packet 1006 */ 1007 if (buffer_len(&input) < block_size) 1008 return SSH_MSG_NONE; 1009 buffer_clear(&incoming_packet); 1010 cp = buffer_append_space(&incoming_packet, block_size); 1011 cipher_crypt(&receive_context, cp, buffer_ptr(&input), 1012 block_size); 1013 cp = buffer_ptr(&incoming_packet); 1014 packet_length = GET_32BIT(cp); 1015 if (packet_length < 1 + 4 || packet_length > 256 * 1024) { 1016 #ifdef PACKET_DEBUG 1017 buffer_dump(&incoming_packet); 1018 #endif 1019 packet_disconnect("Bad packet length %u.", packet_length); 1020 } 1021 DBG(debug("input: packet len %u", packet_length+4)); 1022 buffer_consume(&input, block_size); 1023 } 1024 /* we have a partial packet of block_size bytes */ 1025 need = 4 + packet_length - block_size; 1026 DBG(debug("partial packet %d, need %d, maclen %d", block_size, 1027 need, maclen)); 1028 if (need % block_size != 0) 1029 fatal("padding error: need %d block %d mod %d", 1030 need, block_size, need % block_size); 1031 /* 1032 * check if the entire packet has been received and 1033 * decrypt into incoming_packet 1034 */ 1035 if (buffer_len(&input) < need + maclen) 1036 return SSH_MSG_NONE; 1037 #ifdef PACKET_DEBUG 1038 fprintf(stderr, "read_poll enc/full: "); 1039 buffer_dump(&input); 1040 #endif 1041 cp = buffer_append_space(&incoming_packet, need); 1042 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); 1043 buffer_consume(&input, need); 1044 /* 1045 * compute MAC over seqnr and packet, 1046 * increment sequence number for incoming packet 1047 */ 1048 if (mac && mac->enabled) { 1049 macbuf = mac_compute(mac, p_read.seqnr, 1050 buffer_ptr(&incoming_packet), 1051 buffer_len(&incoming_packet)); 1052 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) 1053 packet_disconnect("Corrupted MAC on input."); 1054 DBG(debug("MAC #%d ok", p_read.seqnr)); 1055 buffer_consume(&input, mac->mac_len); 1056 } 1057 if (seqnr_p != NULL) 1058 *seqnr_p = p_read.seqnr; 1059 if (++p_read.seqnr == 0) 1060 logit("incoming seqnr wraps around"); 1061 if (++p_read.packets == 0) 1062 if (!(datafellows & SSH_BUG_NOREKEY)) 1063 fatal("XXX too many packets with same key"); 1064 p_read.blocks += (packet_length + 4) / block_size; 1065 1066 /* get padlen */ 1067 cp = buffer_ptr(&incoming_packet); 1068 padlen = cp[4]; 1069 DBG(debug("input: padlen %d", padlen)); 1070 if (padlen < 4) 1071 packet_disconnect("Corrupted padlen %d on input.", padlen); 1072 1073 /* skip packet size + padlen, discard padding */ 1074 buffer_consume(&incoming_packet, 4 + 1); 1075 buffer_consume_end(&incoming_packet, padlen); 1076 1077 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); 1078 if (comp && comp->enabled) { 1079 buffer_clear(&compression_buffer); 1080 buffer_uncompress(&incoming_packet, &compression_buffer); 1081 buffer_clear(&incoming_packet); 1082 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1083 buffer_len(&compression_buffer)); 1084 DBG(debug("input: len after de-compress %d", 1085 buffer_len(&incoming_packet))); 1086 } 1087 /* 1088 * get packet type, implies consume. 1089 * return length of payload (without type field) 1090 */ 1091 type = buffer_get_char(&incoming_packet); 1092 if (type == SSH2_MSG_NEWKEYS) 1093 set_newkeys(MODE_IN); 1094 #ifdef PACKET_DEBUG 1095 fprintf(stderr, "read/plain[%d]:\r\n", type); 1096 buffer_dump(&incoming_packet); 1097 #endif 1098 /* reset for next packet */ 1099 packet_length = 0; 1100 return type; 1101 } 1102 1103 int 1104 packet_read_poll_seqnr(u_int32_t *seqnr_p) 1105 { 1106 u_int reason, seqnr; 1107 u_char type; 1108 char *msg; 1109 1110 for (;;) { 1111 if (compat20) { 1112 type = packet_read_poll2(seqnr_p); 1113 if (type) 1114 DBG(debug("received packet type %d", type)); 1115 switch (type) { 1116 case SSH2_MSG_IGNORE: 1117 break; 1118 case SSH2_MSG_DEBUG: 1119 packet_get_char(); 1120 msg = packet_get_string(NULL); 1121 debug("Remote: %.900s", msg); 1122 xfree(msg); 1123 msg = packet_get_string(NULL); 1124 xfree(msg); 1125 break; 1126 case SSH2_MSG_DISCONNECT: 1127 reason = packet_get_int(); 1128 msg = packet_get_string(NULL); 1129 logit("Received disconnect from %s: %u: %.400s", 1130 get_remote_ipaddr(), reason, msg); 1131 xfree(msg); 1132 cleanup_exit(255); 1133 break; 1134 case SSH2_MSG_UNIMPLEMENTED: 1135 seqnr = packet_get_int(); 1136 debug("Received SSH2_MSG_UNIMPLEMENTED for %u", 1137 seqnr); 1138 break; 1139 default: 1140 return type; 1141 break; 1142 } 1143 } else { 1144 type = packet_read_poll1(); 1145 switch (type) { 1146 case SSH_MSG_IGNORE: 1147 break; 1148 case SSH_MSG_DEBUG: 1149 msg = packet_get_string(NULL); 1150 debug("Remote: %.900s", msg); 1151 xfree(msg); 1152 break; 1153 case SSH_MSG_DISCONNECT: 1154 msg = packet_get_string(NULL); 1155 logit("Received disconnect from %s: %.400s", 1156 get_remote_ipaddr(), msg); 1157 cleanup_exit(255); 1158 xfree(msg); 1159 break; 1160 default: 1161 if (type) 1162 DBG(debug("received packet type %d", type)); 1163 return type; 1164 break; 1165 } 1166 } 1167 } 1168 } 1169 1170 int 1171 packet_read_poll(void) 1172 { 1173 return packet_read_poll_seqnr(NULL); 1174 } 1175 1176 /* 1177 * Buffers the given amount of input characters. This is intended to be used 1178 * together with packet_read_poll. 1179 */ 1180 1181 void 1182 packet_process_incoming(const char *buf, u_int len) 1183 { 1184 buffer_append(&input, buf, len); 1185 } 1186 1187 /* Returns a character from the packet. */ 1188 1189 u_int 1190 packet_get_char(void) 1191 { 1192 char ch; 1193 1194 buffer_get(&incoming_packet, &ch, 1); 1195 return (u_char) ch; 1196 } 1197 1198 /* Returns an integer from the packet data. */ 1199 1200 u_int 1201 packet_get_int(void) 1202 { 1203 return buffer_get_int(&incoming_packet); 1204 } 1205 1206 /* 1207 * Returns an arbitrary precision integer from the packet data. The integer 1208 * must have been initialized before this call. 1209 */ 1210 1211 void 1212 packet_get_bignum(BIGNUM * value) 1213 { 1214 buffer_get_bignum(&incoming_packet, value); 1215 } 1216 1217 void 1218 packet_get_bignum2(BIGNUM * value) 1219 { 1220 buffer_get_bignum2(&incoming_packet, value); 1221 } 1222 1223 void * 1224 packet_get_raw(int *length_ptr) 1225 { 1226 int bytes = buffer_len(&incoming_packet); 1227 1228 if (length_ptr != NULL) 1229 *length_ptr = bytes; 1230 return buffer_ptr(&incoming_packet); 1231 } 1232 1233 int 1234 packet_remaining(void) 1235 { 1236 return buffer_len(&incoming_packet); 1237 } 1238 1239 /* 1240 * Returns a string from the packet data. The string is allocated using 1241 * xmalloc; it is the responsibility of the calling program to free it when 1242 * no longer needed. The length_ptr argument may be NULL, or point to an 1243 * integer into which the length of the string is stored. 1244 */ 1245 1246 void * 1247 packet_get_string(u_int *length_ptr) 1248 { 1249 return buffer_get_string(&incoming_packet, length_ptr); 1250 } 1251 1252 /* 1253 * Sends a diagnostic message from the server to the client. This message 1254 * can be sent at any time (but not while constructing another message). The 1255 * message is printed immediately, but only if the client is being executed 1256 * in verbose mode. These messages are primarily intended to ease debugging 1257 * authentication problems. The length of the formatted message must not 1258 * exceed 1024 bytes. This will automatically call packet_write_wait. 1259 */ 1260 1261 void 1262 packet_send_debug(const char *fmt,...) 1263 { 1264 char buf[1024]; 1265 va_list args; 1266 1267 if (compat20 && (datafellows & SSH_BUG_DEBUG)) 1268 return; 1269 1270 va_start(args, fmt); 1271 vsnprintf(buf, sizeof(buf), fmt, args); 1272 va_end(args); 1273 1274 if (compat20) { 1275 packet_start(SSH2_MSG_DEBUG); 1276 packet_put_char(0); /* bool: always display */ 1277 packet_put_cstring(buf); 1278 packet_put_cstring(""); 1279 } else { 1280 packet_start(SSH_MSG_DEBUG); 1281 packet_put_cstring(buf); 1282 } 1283 packet_send(); 1284 packet_write_wait(); 1285 } 1286 1287 /* 1288 * Logs the error plus constructs and sends a disconnect packet, closes the 1289 * connection, and exits. This function never returns. The error message 1290 * should not contain a newline. The length of the formatted message must 1291 * not exceed 1024 bytes. 1292 */ 1293 1294 void 1295 packet_disconnect(const char *fmt,...) 1296 { 1297 char buf[1024]; 1298 va_list args; 1299 static int disconnecting = 0; 1300 1301 if (disconnecting) /* Guard against recursive invocations. */ 1302 fatal("packet_disconnect called recursively."); 1303 disconnecting = 1; 1304 1305 /* 1306 * Format the message. Note that the caller must make sure the 1307 * message is of limited size. 1308 */ 1309 va_start(args, fmt); 1310 vsnprintf(buf, sizeof(buf), fmt, args); 1311 va_end(args); 1312 1313 /* Display the error locally */ 1314 logit("Disconnecting: %.100s", buf); 1315 1316 /* Send the disconnect message to the other side, and wait for it to get sent. */ 1317 if (compat20) { 1318 packet_start(SSH2_MSG_DISCONNECT); 1319 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); 1320 packet_put_cstring(buf); 1321 packet_put_cstring(""); 1322 } else { 1323 packet_start(SSH_MSG_DISCONNECT); 1324 packet_put_cstring(buf); 1325 } 1326 packet_send(); 1327 packet_write_wait(); 1328 1329 /* Stop listening for connections. */ 1330 channel_close_all(); 1331 1332 /* Close the connection. */ 1333 packet_close(); 1334 cleanup_exit(255); 1335 } 1336 1337 /* Checks if there is any buffered output, and tries to write some of the output. */ 1338 1339 void 1340 packet_write_poll(void) 1341 { 1342 int len = buffer_len(&output); 1343 1344 if (len > 0) { 1345 len = write(connection_out, buffer_ptr(&output), len); 1346 if (len <= 0) { 1347 if (errno == EAGAIN) 1348 return; 1349 else 1350 fatal("Write failed: %.100s", strerror(errno)); 1351 } 1352 buffer_consume(&output, len); 1353 } 1354 } 1355 1356 /* 1357 * Calls packet_write_poll repeatedly until all pending output data has been 1358 * written. 1359 */ 1360 1361 void 1362 packet_write_wait(void) 1363 { 1364 fd_set *setp; 1365 1366 setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * 1367 sizeof(fd_mask)); 1368 packet_write_poll(); 1369 while (packet_have_data_to_write()) { 1370 memset(setp, 0, howmany(connection_out + 1, NFDBITS) * 1371 sizeof(fd_mask)); 1372 FD_SET(connection_out, setp); 1373 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && 1374 (errno == EAGAIN || errno == EINTR)) 1375 ; 1376 packet_write_poll(); 1377 } 1378 xfree(setp); 1379 } 1380 1381 /* Returns true if there is buffered data to write to the connection. */ 1382 1383 int 1384 packet_have_data_to_write(void) 1385 { 1386 return buffer_len(&output) != 0; 1387 } 1388 1389 /* Returns true if there is not too much data to write to the connection. */ 1390 1391 int 1392 packet_not_very_much_data_to_write(void) 1393 { 1394 if (interactive_mode) 1395 return buffer_len(&output) < 16384; 1396 else 1397 return buffer_len(&output) < 128 * 1024; 1398 } 1399 1400 static void 1401 packet_set_tos(int interactive) 1402 { 1403 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; 1404 1405 if (!packet_connection_is_on_socket() || 1406 !packet_connection_is_ipv4()) 1407 return; 1408 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, 1409 sizeof(tos)) < 0) 1410 error("setsockopt IP_TOS %d: %.100s:", 1411 tos, strerror(errno)); 1412 } 1413 1414 /* Informs that the current session is interactive. Sets IP flags for that. */ 1415 1416 void 1417 packet_set_interactive(int interactive) 1418 { 1419 static int called = 0; 1420 1421 if (called) 1422 return; 1423 called = 1; 1424 1425 /* Record that we are in interactive mode. */ 1426 interactive_mode = interactive; 1427 1428 /* Only set socket options if using a socket. */ 1429 if (!packet_connection_is_on_socket()) 1430 return; 1431 if (interactive) 1432 set_nodelay(connection_in); 1433 packet_set_tos(interactive); 1434 } 1435 1436 /* Returns true if the current connection is interactive. */ 1437 1438 int 1439 packet_is_interactive(void) 1440 { 1441 return interactive_mode; 1442 } 1443 1444 u_int 1445 packet_set_maxsize(u_int s) 1446 { 1447 static int called = 0; 1448 1449 if (called) { 1450 logit("packet_set_maxsize: called twice: old %d new %d", 1451 max_packet_size, s); 1452 return -1; 1453 } 1454 if (s < 4 * 1024 || s > 1024 * 1024) { 1455 logit("packet_set_maxsize: bad size %d", s); 1456 return -1; 1457 } 1458 called = 1; 1459 debug("packet_set_maxsize: setting to %d", s); 1460 max_packet_size = s; 1461 return s; 1462 } 1463 1464 /* roundup current message to pad bytes */ 1465 void 1466 packet_add_padding(u_char pad) 1467 { 1468 extra_pad = pad; 1469 } 1470 1471 /* 1472 * 9.2. Ignored Data Message 1473 * 1474 * byte SSH_MSG_IGNORE 1475 * string data 1476 * 1477 * All implementations MUST understand (and ignore) this message at any 1478 * time (after receiving the protocol version). No implementation is 1479 * required to send them. This message can be used as an additional 1480 * protection measure against advanced traffic analysis techniques. 1481 */ 1482 void 1483 packet_send_ignore(int nbytes) 1484 { 1485 u_int32_t rand = 0; 1486 int i; 1487 1488 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); 1489 packet_put_int(nbytes); 1490 for (i = 0; i < nbytes; i++) { 1491 if (i % 4 == 0) 1492 rand = arc4random(); 1493 packet_put_char(rand & 0xff); 1494 rand >>= 8; 1495 } 1496 } 1497 1498 #define MAX_PACKETS (1<<31) 1499 int 1500 packet_need_rekeying(void) 1501 { 1502 if (datafellows & SSH_BUG_NOREKEY) 1503 return 0; 1504 return 1505 (p_send.packets > MAX_PACKETS) || 1506 (p_read.packets > MAX_PACKETS) || 1507 (max_blocks_out && (p_send.blocks > max_blocks_out)) || 1508 (max_blocks_in && (p_read.blocks > max_blocks_in)); 1509 } 1510 1511 void 1512 packet_set_rekey_limit(u_int32_t bytes) 1513 { 1514 rekey_limit = bytes; 1515 } 1516