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 1.119 2005/07/28 17:36:22 markus 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 /* Set to true if we are the server side. */ 120 static int server_side = 0; 121 122 /* Set to true if we are authenticated. */ 123 static int after_authentication = 0; 124 125 /* Session key information for Encryption and MAC */ 126 Newkeys *newkeys[MODE_MAX]; 127 static struct packet_state { 128 u_int32_t seqnr; 129 u_int32_t packets; 130 u_int64_t blocks; 131 } p_read, p_send; 132 133 static u_int64_t max_blocks_in, max_blocks_out; 134 static u_int32_t rekey_limit; 135 136 /* Session key for protocol v1 */ 137 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; 138 static u_int ssh1_keylen; 139 140 /* roundup current message to extra_pad bytes */ 141 static u_char extra_pad = 0; 142 143 struct packet { 144 TAILQ_ENTRY(packet) next; 145 u_char type; 146 Buffer payload; 147 }; 148 TAILQ_HEAD(, packet) outgoing; 149 150 /* 151 * Sets the descriptors used for communication. Disables encryption until 152 * packet_set_encryption_key is called. 153 */ 154 void 155 packet_set_connection(int fd_in, int fd_out) 156 { 157 Cipher *none = cipher_by_name("none"); 158 159 if (none == NULL) 160 fatal("packet_set_connection: cannot load cipher 'none'"); 161 connection_in = fd_in; 162 connection_out = fd_out; 163 cipher_init(&send_context, none, (const u_char *)"", 164 0, NULL, 0, CIPHER_ENCRYPT); 165 cipher_init(&receive_context, none, (const u_char *)"", 166 0, NULL, 0, CIPHER_DECRYPT); 167 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; 168 if (!initialized) { 169 initialized = 1; 170 buffer_init(&input); 171 buffer_init(&output); 172 buffer_init(&outgoing_packet); 173 buffer_init(&incoming_packet); 174 TAILQ_INIT(&outgoing); 175 } 176 } 177 178 /* Returns 1 if remote host is connected via socket, 0 if not. */ 179 180 int 181 packet_connection_is_on_socket(void) 182 { 183 struct sockaddr_storage from, to; 184 socklen_t fromlen, tolen; 185 186 /* filedescriptors in and out are the same, so it's a socket */ 187 if (connection_in == connection_out) 188 return 1; 189 fromlen = sizeof(from); 190 memset(&from, 0, sizeof(from)); 191 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) 192 return 0; 193 tolen = sizeof(to); 194 memset(&to, 0, sizeof(to)); 195 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) 196 return 0; 197 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) 198 return 0; 199 if (from.ss_family != AF_INET && from.ss_family != AF_INET6) 200 return 0; 201 return 1; 202 } 203 204 /* 205 * Exports an IV from the CipherContext required to export the key 206 * state back from the unprivileged child to the privileged parent 207 * process. 208 */ 209 210 void 211 packet_get_keyiv(int mode, u_char *iv, u_int len) 212 { 213 CipherContext *cc; 214 215 if (mode == MODE_OUT) 216 cc = &send_context; 217 else 218 cc = &receive_context; 219 220 cipher_get_keyiv(cc, iv, len); 221 } 222 223 int 224 packet_get_keycontext(int mode, u_char *dat) 225 { 226 CipherContext *cc; 227 228 if (mode == MODE_OUT) 229 cc = &send_context; 230 else 231 cc = &receive_context; 232 233 return (cipher_get_keycontext(cc, dat)); 234 } 235 236 void 237 packet_set_keycontext(int mode, u_char *dat) 238 { 239 CipherContext *cc; 240 241 if (mode == MODE_OUT) 242 cc = &send_context; 243 else 244 cc = &receive_context; 245 246 cipher_set_keycontext(cc, dat); 247 } 248 249 int 250 packet_get_keyiv_len(int mode) 251 { 252 CipherContext *cc; 253 254 if (mode == MODE_OUT) 255 cc = &send_context; 256 else 257 cc = &receive_context; 258 259 return (cipher_get_keyiv_len(cc)); 260 } 261 void 262 packet_set_iv(int mode, u_char *dat) 263 { 264 CipherContext *cc; 265 266 if (mode == MODE_OUT) 267 cc = &send_context; 268 else 269 cc = &receive_context; 270 271 cipher_set_keyiv(cc, dat); 272 } 273 int 274 packet_get_ssh1_cipher(void) 275 { 276 return (cipher_get_number(receive_context.cipher)); 277 } 278 279 void 280 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets) 281 { 282 struct packet_state *state; 283 284 state = (mode == MODE_IN) ? &p_read : &p_send; 285 *seqnr = state->seqnr; 286 *blocks = state->blocks; 287 *packets = state->packets; 288 } 289 290 void 291 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets) 292 { 293 struct packet_state *state; 294 295 state = (mode == MODE_IN) ? &p_read : &p_send; 296 state->seqnr = seqnr; 297 state->blocks = blocks; 298 state->packets = packets; 299 } 300 301 /* returns 1 if connection is via ipv4 */ 302 303 int 304 packet_connection_is_ipv4(void) 305 { 306 struct sockaddr_storage to; 307 socklen_t tolen = sizeof(to); 308 309 memset(&to, 0, sizeof(to)); 310 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) 311 return 0; 312 if (to.ss_family == AF_INET) 313 return 1; 314 #ifdef IPV4_IN_IPV6 315 if (to.ss_family == AF_INET6 && 316 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) 317 return 1; 318 #endif 319 return 0; 320 } 321 322 /* Sets the connection into non-blocking mode. */ 323 324 void 325 packet_set_nonblocking(void) 326 { 327 /* Set the socket into non-blocking mode. */ 328 set_nonblock(connection_in); 329 330 if (connection_out != connection_in) 331 set_nonblock(connection_out); 332 } 333 334 /* Returns the socket used for reading. */ 335 336 int 337 packet_get_connection_in(void) 338 { 339 return connection_in; 340 } 341 342 /* Returns the descriptor used for writing. */ 343 344 int 345 packet_get_connection_out(void) 346 { 347 return connection_out; 348 } 349 350 /* Closes the connection and clears and frees internal data structures. */ 351 352 void 353 packet_close(void) 354 { 355 if (!initialized) 356 return; 357 initialized = 0; 358 if (connection_in == connection_out) { 359 shutdown(connection_out, SHUT_RDWR); 360 close(connection_out); 361 } else { 362 close(connection_in); 363 close(connection_out); 364 } 365 buffer_free(&input); 366 buffer_free(&output); 367 buffer_free(&outgoing_packet); 368 buffer_free(&incoming_packet); 369 if (compression_buffer_ready) { 370 buffer_free(&compression_buffer); 371 buffer_compress_uninit(); 372 } 373 cipher_cleanup(&send_context); 374 cipher_cleanup(&receive_context); 375 } 376 377 /* Sets remote side protocol flags. */ 378 379 void 380 packet_set_protocol_flags(u_int protocol_flags) 381 { 382 remote_protocol_flags = protocol_flags; 383 } 384 385 /* Returns the remote protocol flags set earlier by the above function. */ 386 387 u_int 388 packet_get_protocol_flags(void) 389 { 390 return remote_protocol_flags; 391 } 392 393 /* 394 * Starts packet compression from the next packet on in both directions. 395 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. 396 */ 397 398 static void 399 packet_init_compression(void) 400 { 401 if (compression_buffer_ready == 1) 402 return; 403 compression_buffer_ready = 1; 404 buffer_init(&compression_buffer); 405 } 406 407 void 408 packet_start_compression(int level) 409 { 410 if (packet_compression && !compat20) 411 fatal("Compression already enabled."); 412 packet_compression = 1; 413 packet_init_compression(); 414 buffer_compress_init_send(level); 415 buffer_compress_init_recv(); 416 } 417 418 /* 419 * Causes any further packets to be encrypted using the given key. The same 420 * key is used for both sending and reception. However, both directions are 421 * encrypted independently of each other. 422 */ 423 424 void 425 packet_set_encryption_key(const u_char *key, u_int keylen, 426 int number) 427 { 428 Cipher *cipher = cipher_by_number(number); 429 430 if (cipher == NULL) 431 fatal("packet_set_encryption_key: unknown cipher number %d", number); 432 if (keylen < 20) 433 fatal("packet_set_encryption_key: keylen too small: %d", keylen); 434 if (keylen > SSH_SESSION_KEY_LENGTH) 435 fatal("packet_set_encryption_key: keylen too big: %d", keylen); 436 memcpy(ssh1_key, key, keylen); 437 ssh1_keylen = keylen; 438 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); 439 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); 440 } 441 442 u_int 443 packet_get_encryption_key(u_char *key) 444 { 445 if (key == NULL) 446 return (ssh1_keylen); 447 memcpy(key, ssh1_key, ssh1_keylen); 448 return (ssh1_keylen); 449 } 450 451 /* Start constructing a packet to send. */ 452 void 453 packet_start(u_char type) 454 { 455 u_char buf[9]; 456 int len; 457 458 DBG(debug("packet_start[%d]", type)); 459 len = compat20 ? 6 : 9; 460 memset(buf, 0, len - 1); 461 buf[len - 1] = type; 462 buffer_clear(&outgoing_packet); 463 buffer_append(&outgoing_packet, buf, len); 464 } 465 466 /* Append payload. */ 467 void 468 packet_put_char(int value) 469 { 470 char ch = value; 471 472 buffer_append(&outgoing_packet, &ch, 1); 473 } 474 void 475 packet_put_int(u_int value) 476 { 477 buffer_put_int(&outgoing_packet, value); 478 } 479 void 480 packet_put_string(const void *buf, u_int len) 481 { 482 buffer_put_string(&outgoing_packet, buf, len); 483 } 484 void 485 packet_put_cstring(const char *str) 486 { 487 buffer_put_cstring(&outgoing_packet, str); 488 } 489 void 490 packet_put_raw(const void *buf, u_int len) 491 { 492 buffer_append(&outgoing_packet, buf, len); 493 } 494 void 495 packet_put_bignum(BIGNUM * value) 496 { 497 buffer_put_bignum(&outgoing_packet, value); 498 } 499 void 500 packet_put_bignum2(BIGNUM * value) 501 { 502 buffer_put_bignum2(&outgoing_packet, value); 503 } 504 505 /* 506 * Finalizes and sends the packet. If the encryption key has been set, 507 * encrypts the packet before sending. 508 */ 509 510 static void 511 packet_send1(void) 512 { 513 u_char buf[8], *cp; 514 int i, padding, len; 515 u_int checksum; 516 u_int32_t rnd = 0; 517 518 /* 519 * If using packet compression, compress the payload of the outgoing 520 * packet. 521 */ 522 if (packet_compression) { 523 buffer_clear(&compression_buffer); 524 /* Skip padding. */ 525 buffer_consume(&outgoing_packet, 8); 526 /* padding */ 527 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); 528 buffer_compress(&outgoing_packet, &compression_buffer); 529 buffer_clear(&outgoing_packet); 530 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 531 buffer_len(&compression_buffer)); 532 } 533 /* Compute packet length without padding (add checksum, remove padding). */ 534 len = buffer_len(&outgoing_packet) + 4 - 8; 535 536 /* Insert padding. Initialized to zero in packet_start1() */ 537 padding = 8 - len % 8; 538 if (!send_context.plaintext) { 539 cp = buffer_ptr(&outgoing_packet); 540 for (i = 0; i < padding; i++) { 541 if (i % 4 == 0) 542 rnd = arc4random(); 543 cp[7 - i] = rnd & 0xff; 544 rnd >>= 8; 545 } 546 } 547 buffer_consume(&outgoing_packet, 8 - padding); 548 549 /* Add check bytes. */ 550 checksum = ssh_crc32(buffer_ptr(&outgoing_packet), 551 buffer_len(&outgoing_packet)); 552 PUT_32BIT(buf, checksum); 553 buffer_append(&outgoing_packet, buf, 4); 554 555 #ifdef PACKET_DEBUG 556 fprintf(stderr, "packet_send plain: "); 557 buffer_dump(&outgoing_packet); 558 #endif 559 560 /* Append to output. */ 561 PUT_32BIT(buf, len); 562 buffer_append(&output, buf, 4); 563 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 564 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 565 buffer_len(&outgoing_packet)); 566 567 #ifdef PACKET_DEBUG 568 fprintf(stderr, "encrypted: "); 569 buffer_dump(&output); 570 #endif 571 572 buffer_clear(&outgoing_packet); 573 574 /* 575 * Note that the packet is now only buffered in output. It won\'t be 576 * actually sent until packet_write_wait or packet_write_poll is 577 * called. 578 */ 579 } 580 581 void 582 set_newkeys(int mode) 583 { 584 Enc *enc; 585 Mac *mac; 586 Comp *comp; 587 CipherContext *cc; 588 u_int64_t *max_blocks; 589 int crypt_type; 590 591 debug2("set_newkeys: mode %d", mode); 592 593 if (mode == MODE_OUT) { 594 cc = &send_context; 595 crypt_type = CIPHER_ENCRYPT; 596 p_send.packets = p_send.blocks = 0; 597 max_blocks = &max_blocks_out; 598 } else { 599 cc = &receive_context; 600 crypt_type = CIPHER_DECRYPT; 601 p_read.packets = p_read.blocks = 0; 602 max_blocks = &max_blocks_in; 603 } 604 if (newkeys[mode] != NULL) { 605 debug("set_newkeys: rekeying"); 606 cipher_cleanup(cc); 607 enc = &newkeys[mode]->enc; 608 mac = &newkeys[mode]->mac; 609 comp = &newkeys[mode]->comp; 610 memset(mac->key, 0, mac->key_len); 611 xfree(enc->name); 612 xfree(enc->iv); 613 xfree(enc->key); 614 xfree(mac->name); 615 xfree(mac->key); 616 xfree(comp->name); 617 xfree(newkeys[mode]); 618 } 619 newkeys[mode] = kex_get_newkeys(mode); 620 if (newkeys[mode] == NULL) 621 fatal("newkeys: no keys for mode %d", mode); 622 enc = &newkeys[mode]->enc; 623 mac = &newkeys[mode]->mac; 624 comp = &newkeys[mode]->comp; 625 if (mac->md != NULL) 626 mac->enabled = 1; 627 DBG(debug("cipher_init_context: %d", mode)); 628 cipher_init(cc, enc->cipher, enc->key, enc->key_len, 629 enc->iv, enc->block_size, crypt_type); 630 /* Deleting the keys does not gain extra security */ 631 /* memset(enc->iv, 0, enc->block_size); 632 memset(enc->key, 0, enc->key_len); */ 633 if ((comp->type == COMP_ZLIB || 634 (comp->type == COMP_DELAYED && after_authentication)) && 635 comp->enabled == 0) { 636 packet_init_compression(); 637 if (mode == MODE_OUT) 638 buffer_compress_init_send(6); 639 else 640 buffer_compress_init_recv(); 641 comp->enabled = 1; 642 } 643 /* 644 * The 2^(blocksize*2) limit is too expensive for 3DES, 645 * blowfish, etc, so enforce a 1GB limit for small blocksizes. 646 */ 647 if (enc->block_size >= 16) 648 *max_blocks = (u_int64_t)1 << (enc->block_size*2); 649 else 650 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; 651 if (rekey_limit) 652 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); 653 } 654 655 /* 656 * Delayed compression for SSH2 is enabled after authentication: 657 * This happans on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent, 658 * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received. 659 */ 660 static void 661 packet_enable_delayed_compress(void) 662 { 663 Comp *comp = NULL; 664 int mode; 665 666 /* 667 * Remember that we are past the authentication step, so rekeying 668 * with COMP_DELAYED will turn on compression immediately. 669 */ 670 after_authentication = 1; 671 for (mode = 0; mode < MODE_MAX; mode++) { 672 comp = &newkeys[mode]->comp; 673 if (comp && !comp->enabled && comp->type == COMP_DELAYED) { 674 packet_init_compression(); 675 if (mode == MODE_OUT) 676 buffer_compress_init_send(6); 677 else 678 buffer_compress_init_recv(); 679 comp->enabled = 1; 680 } 681 } 682 } 683 684 /* 685 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) 686 */ 687 static void 688 packet_send2_wrapped(void) 689 { 690 u_char type, *cp, *macbuf = NULL; 691 u_char padlen, pad; 692 u_int packet_length = 0; 693 u_int i, len; 694 u_int32_t rnd = 0; 695 Enc *enc = NULL; 696 Mac *mac = NULL; 697 Comp *comp = NULL; 698 int block_size; 699 700 if (newkeys[MODE_OUT] != NULL) { 701 enc = &newkeys[MODE_OUT]->enc; 702 mac = &newkeys[MODE_OUT]->mac; 703 comp = &newkeys[MODE_OUT]->comp; 704 } 705 block_size = enc ? enc->block_size : 8; 706 707 cp = buffer_ptr(&outgoing_packet); 708 type = cp[5]; 709 710 #ifdef PACKET_DEBUG 711 fprintf(stderr, "plain: "); 712 buffer_dump(&outgoing_packet); 713 #endif 714 715 if (comp && comp->enabled) { 716 len = buffer_len(&outgoing_packet); 717 /* skip header, compress only payload */ 718 buffer_consume(&outgoing_packet, 5); 719 buffer_clear(&compression_buffer); 720 buffer_compress(&outgoing_packet, &compression_buffer); 721 buffer_clear(&outgoing_packet); 722 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); 723 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 724 buffer_len(&compression_buffer)); 725 DBG(debug("compression: raw %d compressed %d", len, 726 buffer_len(&outgoing_packet))); 727 } 728 729 /* sizeof (packet_len + pad_len + payload) */ 730 len = buffer_len(&outgoing_packet); 731 732 /* 733 * calc size of padding, alloc space, get random data, 734 * minimum padding is 4 bytes 735 */ 736 padlen = block_size - (len % block_size); 737 if (padlen < 4) 738 padlen += block_size; 739 if (extra_pad) { 740 /* will wrap if extra_pad+padlen > 255 */ 741 extra_pad = roundup(extra_pad, block_size); 742 pad = extra_pad - ((len + padlen) % extra_pad); 743 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", 744 pad, len, padlen, extra_pad); 745 padlen += pad; 746 extra_pad = 0; 747 } 748 cp = buffer_append_space(&outgoing_packet, padlen); 749 if (enc && !send_context.plaintext) { 750 /* random padding */ 751 for (i = 0; i < padlen; i++) { 752 if (i % 4 == 0) 753 rnd = arc4random(); 754 cp[i] = rnd & 0xff; 755 rnd >>= 8; 756 } 757 } else { 758 /* clear padding */ 759 memset(cp, 0, padlen); 760 } 761 /* packet_length includes payload, padding and padding length field */ 762 packet_length = buffer_len(&outgoing_packet) - 4; 763 cp = buffer_ptr(&outgoing_packet); 764 PUT_32BIT(cp, packet_length); 765 cp[4] = padlen; 766 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); 767 768 /* compute MAC over seqnr and packet(length fields, payload, padding) */ 769 if (mac && mac->enabled) { 770 macbuf = mac_compute(mac, p_send.seqnr, 771 buffer_ptr(&outgoing_packet), 772 buffer_len(&outgoing_packet)); 773 DBG(debug("done calc MAC out #%d", p_send.seqnr)); 774 } 775 /* encrypt packet and append to output buffer. */ 776 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 777 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 778 buffer_len(&outgoing_packet)); 779 /* append unencrypted MAC */ 780 if (mac && mac->enabled) 781 buffer_append(&output, (char *)macbuf, mac->mac_len); 782 #ifdef PACKET_DEBUG 783 fprintf(stderr, "encrypted: "); 784 buffer_dump(&output); 785 #endif 786 /* increment sequence number for outgoing packets */ 787 if (++p_send.seqnr == 0) 788 logit("outgoing seqnr wraps around"); 789 if (++p_send.packets == 0) 790 if (!(datafellows & SSH_BUG_NOREKEY)) 791 fatal("XXX too many packets with same key"); 792 p_send.blocks += (packet_length + 4) / block_size; 793 buffer_clear(&outgoing_packet); 794 795 if (type == SSH2_MSG_NEWKEYS) 796 set_newkeys(MODE_OUT); 797 else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side) 798 packet_enable_delayed_compress(); 799 } 800 801 static void 802 packet_send2(void) 803 { 804 static int rekeying = 0; 805 struct packet *p; 806 u_char type, *cp; 807 808 cp = buffer_ptr(&outgoing_packet); 809 type = cp[5]; 810 811 /* during rekeying we can only send key exchange messages */ 812 if (rekeying) { 813 if (!((type >= SSH2_MSG_TRANSPORT_MIN) && 814 (type <= SSH2_MSG_TRANSPORT_MAX))) { 815 debug("enqueue packet: %u", type); 816 p = xmalloc(sizeof(*p)); 817 p->type = type; 818 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); 819 buffer_init(&outgoing_packet); 820 TAILQ_INSERT_TAIL(&outgoing, p, next); 821 return; 822 } 823 } 824 825 /* rekeying starts with sending KEXINIT */ 826 if (type == SSH2_MSG_KEXINIT) 827 rekeying = 1; 828 829 packet_send2_wrapped(); 830 831 /* after a NEWKEYS message we can send the complete queue */ 832 if (type == SSH2_MSG_NEWKEYS) { 833 rekeying = 0; 834 while ((p = TAILQ_FIRST(&outgoing))) { 835 type = p->type; 836 debug("dequeue packet: %u", type); 837 buffer_free(&outgoing_packet); 838 memcpy(&outgoing_packet, &p->payload, 839 sizeof(Buffer)); 840 TAILQ_REMOVE(&outgoing, p, next); 841 xfree(p); 842 packet_send2_wrapped(); 843 } 844 } 845 } 846 847 void 848 packet_send(void) 849 { 850 if (compat20) 851 packet_send2(); 852 else 853 packet_send1(); 854 DBG(debug("packet_send done")); 855 } 856 857 /* 858 * Waits until a packet has been received, and returns its type. Note that 859 * no other data is processed until this returns, so this function should not 860 * be used during the interactive session. 861 */ 862 863 int 864 packet_read_seqnr(u_int32_t *seqnr_p) 865 { 866 int type, len; 867 fd_set *setp; 868 char buf[8192]; 869 DBG(debug("packet_read()")); 870 871 setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * 872 sizeof(fd_mask)); 873 874 /* Since we are blocking, ensure that all written packets have been sent. */ 875 packet_write_wait(); 876 877 /* Stay in the loop until we have received a complete packet. */ 878 for (;;) { 879 /* Try to read a packet from the buffer. */ 880 type = packet_read_poll_seqnr(seqnr_p); 881 if (!compat20 && ( 882 type == SSH_SMSG_SUCCESS 883 || type == SSH_SMSG_FAILURE 884 || type == SSH_CMSG_EOF 885 || type == SSH_CMSG_EXIT_CONFIRMATION)) 886 packet_check_eom(); 887 /* If we got a packet, return it. */ 888 if (type != SSH_MSG_NONE) { 889 xfree(setp); 890 return type; 891 } 892 /* 893 * Otherwise, wait for some data to arrive, add it to the 894 * buffer, and try again. 895 */ 896 memset(setp, 0, howmany(connection_in + 1, NFDBITS) * 897 sizeof(fd_mask)); 898 FD_SET(connection_in, setp); 899 900 /* Wait for some data to arrive. */ 901 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && 902 (errno == EAGAIN || errno == EINTR)) 903 ; 904 905 /* Read data from the socket. */ 906 len = read(connection_in, buf, sizeof(buf)); 907 if (len == 0) { 908 logit("Connection closed by %.200s", get_remote_ipaddr()); 909 cleanup_exit(255); 910 } 911 if (len < 0) 912 fatal("Read from socket failed: %.100s", strerror(errno)); 913 /* Append it to the buffer. */ 914 packet_process_incoming(buf, len); 915 } 916 /* NOTREACHED */ 917 } 918 919 int 920 packet_read(void) 921 { 922 return packet_read_seqnr(NULL); 923 } 924 925 /* 926 * Waits until a packet has been received, verifies that its type matches 927 * that given, and gives a fatal error and exits if there is a mismatch. 928 */ 929 930 void 931 packet_read_expect(int expected_type) 932 { 933 int type; 934 935 type = packet_read(); 936 if (type != expected_type) 937 packet_disconnect("Protocol error: expected packet type %d, got %d", 938 expected_type, type); 939 } 940 941 /* Checks if a full packet is available in the data received so far via 942 * packet_process_incoming. If so, reads the packet; otherwise returns 943 * SSH_MSG_NONE. This does not wait for data from the connection. 944 * 945 * SSH_MSG_DISCONNECT is handled specially here. Also, 946 * SSH_MSG_IGNORE messages are skipped by this function and are never returned 947 * to higher levels. 948 */ 949 950 static int 951 packet_read_poll1(void) 952 { 953 u_int len, padded_len; 954 u_char *cp, type; 955 u_int checksum, stored_checksum; 956 957 /* Check if input size is less than minimum packet size. */ 958 if (buffer_len(&input) < 4 + 8) 959 return SSH_MSG_NONE; 960 /* Get length of incoming packet. */ 961 cp = buffer_ptr(&input); 962 len = GET_32BIT(cp); 963 if (len < 1 + 2 + 2 || len > 256 * 1024) 964 packet_disconnect("Bad packet length %u.", len); 965 padded_len = (len + 8) & ~7; 966 967 /* Check if the packet has been entirely received. */ 968 if (buffer_len(&input) < 4 + padded_len) 969 return SSH_MSG_NONE; 970 971 /* The entire packet is in buffer. */ 972 973 /* Consume packet length. */ 974 buffer_consume(&input, 4); 975 976 /* 977 * Cryptographic attack detector for ssh 978 * (C)1998 CORE-SDI, Buenos Aires Argentina 979 * Ariel Futoransky(futo@core-sdi.com) 980 */ 981 if (!receive_context.plaintext && 982 detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) 983 packet_disconnect("crc32 compensation attack: network attack detected"); 984 985 /* Decrypt data to incoming_packet. */ 986 buffer_clear(&incoming_packet); 987 cp = buffer_append_space(&incoming_packet, padded_len); 988 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); 989 990 buffer_consume(&input, padded_len); 991 992 #ifdef PACKET_DEBUG 993 fprintf(stderr, "read_poll plain: "); 994 buffer_dump(&incoming_packet); 995 #endif 996 997 /* Compute packet checksum. */ 998 checksum = ssh_crc32(buffer_ptr(&incoming_packet), 999 buffer_len(&incoming_packet) - 4); 1000 1001 /* Skip padding. */ 1002 buffer_consume(&incoming_packet, 8 - len % 8); 1003 1004 /* Test check bytes. */ 1005 if (len != buffer_len(&incoming_packet)) 1006 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", 1007 len, buffer_len(&incoming_packet)); 1008 1009 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; 1010 stored_checksum = GET_32BIT(cp); 1011 if (checksum != stored_checksum) 1012 packet_disconnect("Corrupted check bytes on input."); 1013 buffer_consume_end(&incoming_packet, 4); 1014 1015 if (packet_compression) { 1016 buffer_clear(&compression_buffer); 1017 buffer_uncompress(&incoming_packet, &compression_buffer); 1018 buffer_clear(&incoming_packet); 1019 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1020 buffer_len(&compression_buffer)); 1021 } 1022 type = buffer_get_char(&incoming_packet); 1023 if (type < SSH_MSG_MIN || type > SSH_MSG_MAX) 1024 packet_disconnect("Invalid ssh1 packet type: %d", type); 1025 return type; 1026 } 1027 1028 static int 1029 packet_read_poll2(u_int32_t *seqnr_p) 1030 { 1031 static u_int packet_length = 0; 1032 u_int padlen, need; 1033 u_char *macbuf, *cp, type; 1034 u_int maclen, block_size; 1035 Enc *enc = NULL; 1036 Mac *mac = NULL; 1037 Comp *comp = NULL; 1038 1039 if (newkeys[MODE_IN] != NULL) { 1040 enc = &newkeys[MODE_IN]->enc; 1041 mac = &newkeys[MODE_IN]->mac; 1042 comp = &newkeys[MODE_IN]->comp; 1043 } 1044 maclen = mac && mac->enabled ? mac->mac_len : 0; 1045 block_size = enc ? enc->block_size : 8; 1046 1047 if (packet_length == 0) { 1048 /* 1049 * check if input size is less than the cipher block size, 1050 * decrypt first block and extract length of incoming packet 1051 */ 1052 if (buffer_len(&input) < block_size) 1053 return SSH_MSG_NONE; 1054 buffer_clear(&incoming_packet); 1055 cp = buffer_append_space(&incoming_packet, block_size); 1056 cipher_crypt(&receive_context, cp, buffer_ptr(&input), 1057 block_size); 1058 cp = buffer_ptr(&incoming_packet); 1059 packet_length = GET_32BIT(cp); 1060 if (packet_length < 1 + 4 || packet_length > 256 * 1024) { 1061 #ifdef PACKET_DEBUG 1062 buffer_dump(&incoming_packet); 1063 #endif 1064 packet_disconnect("Bad packet length %u.", packet_length); 1065 } 1066 DBG(debug("input: packet len %u", packet_length+4)); 1067 buffer_consume(&input, block_size); 1068 } 1069 /* we have a partial packet of block_size bytes */ 1070 need = 4 + packet_length - block_size; 1071 DBG(debug("partial packet %d, need %d, maclen %d", block_size, 1072 need, maclen)); 1073 if (need % block_size != 0) 1074 fatal("padding error: need %d block %d mod %d", 1075 need, block_size, need % block_size); 1076 /* 1077 * check if the entire packet has been received and 1078 * decrypt into incoming_packet 1079 */ 1080 if (buffer_len(&input) < need + maclen) 1081 return SSH_MSG_NONE; 1082 #ifdef PACKET_DEBUG 1083 fprintf(stderr, "read_poll enc/full: "); 1084 buffer_dump(&input); 1085 #endif 1086 cp = buffer_append_space(&incoming_packet, need); 1087 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); 1088 buffer_consume(&input, need); 1089 /* 1090 * compute MAC over seqnr and packet, 1091 * increment sequence number for incoming packet 1092 */ 1093 if (mac && mac->enabled) { 1094 macbuf = mac_compute(mac, p_read.seqnr, 1095 buffer_ptr(&incoming_packet), 1096 buffer_len(&incoming_packet)); 1097 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) 1098 packet_disconnect("Corrupted MAC on input."); 1099 DBG(debug("MAC #%d ok", p_read.seqnr)); 1100 buffer_consume(&input, mac->mac_len); 1101 } 1102 if (seqnr_p != NULL) 1103 *seqnr_p = p_read.seqnr; 1104 if (++p_read.seqnr == 0) 1105 logit("incoming seqnr wraps around"); 1106 if (++p_read.packets == 0) 1107 if (!(datafellows & SSH_BUG_NOREKEY)) 1108 fatal("XXX too many packets with same key"); 1109 p_read.blocks += (packet_length + 4) / block_size; 1110 1111 /* get padlen */ 1112 cp = buffer_ptr(&incoming_packet); 1113 padlen = cp[4]; 1114 DBG(debug("input: padlen %d", padlen)); 1115 if (padlen < 4) 1116 packet_disconnect("Corrupted padlen %d on input.", padlen); 1117 1118 /* skip packet size + padlen, discard padding */ 1119 buffer_consume(&incoming_packet, 4 + 1); 1120 buffer_consume_end(&incoming_packet, padlen); 1121 1122 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); 1123 if (comp && comp->enabled) { 1124 buffer_clear(&compression_buffer); 1125 buffer_uncompress(&incoming_packet, &compression_buffer); 1126 buffer_clear(&incoming_packet); 1127 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1128 buffer_len(&compression_buffer)); 1129 DBG(debug("input: len after de-compress %d", 1130 buffer_len(&incoming_packet))); 1131 } 1132 /* 1133 * get packet type, implies consume. 1134 * return length of payload (without type field) 1135 */ 1136 type = buffer_get_char(&incoming_packet); 1137 if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN) 1138 packet_disconnect("Invalid ssh2 packet type: %d", type); 1139 if (type == SSH2_MSG_NEWKEYS) 1140 set_newkeys(MODE_IN); 1141 else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side) 1142 packet_enable_delayed_compress(); 1143 #ifdef PACKET_DEBUG 1144 fprintf(stderr, "read/plain[%d]:\r\n", type); 1145 buffer_dump(&incoming_packet); 1146 #endif 1147 /* reset for next packet */ 1148 packet_length = 0; 1149 return type; 1150 } 1151 1152 int 1153 packet_read_poll_seqnr(u_int32_t *seqnr_p) 1154 { 1155 u_int reason, seqnr; 1156 u_char type; 1157 char *msg; 1158 1159 for (;;) { 1160 if (compat20) { 1161 type = packet_read_poll2(seqnr_p); 1162 if (type) 1163 DBG(debug("received packet type %d", type)); 1164 switch (type) { 1165 case SSH2_MSG_IGNORE: 1166 break; 1167 case SSH2_MSG_DEBUG: 1168 packet_get_char(); 1169 msg = packet_get_string(NULL); 1170 debug("Remote: %.900s", msg); 1171 xfree(msg); 1172 msg = packet_get_string(NULL); 1173 xfree(msg); 1174 break; 1175 case SSH2_MSG_DISCONNECT: 1176 reason = packet_get_int(); 1177 msg = packet_get_string(NULL); 1178 logit("Received disconnect from %s: %u: %.400s", 1179 get_remote_ipaddr(), reason, msg); 1180 xfree(msg); 1181 cleanup_exit(255); 1182 break; 1183 case SSH2_MSG_UNIMPLEMENTED: 1184 seqnr = packet_get_int(); 1185 debug("Received SSH2_MSG_UNIMPLEMENTED for %u", 1186 seqnr); 1187 break; 1188 default: 1189 return type; 1190 break; 1191 } 1192 } else { 1193 type = packet_read_poll1(); 1194 switch (type) { 1195 case SSH_MSG_IGNORE: 1196 break; 1197 case SSH_MSG_DEBUG: 1198 msg = packet_get_string(NULL); 1199 debug("Remote: %.900s", msg); 1200 xfree(msg); 1201 break; 1202 case SSH_MSG_DISCONNECT: 1203 msg = packet_get_string(NULL); 1204 logit("Received disconnect from %s: %.400s", 1205 get_remote_ipaddr(), msg); 1206 cleanup_exit(255); 1207 xfree(msg); 1208 break; 1209 default: 1210 if (type) 1211 DBG(debug("received packet type %d", type)); 1212 return type; 1213 break; 1214 } 1215 } 1216 } 1217 } 1218 1219 int 1220 packet_read_poll(void) 1221 { 1222 return packet_read_poll_seqnr(NULL); 1223 } 1224 1225 /* 1226 * Buffers the given amount of input characters. This is intended to be used 1227 * together with packet_read_poll. 1228 */ 1229 1230 void 1231 packet_process_incoming(const char *buf, u_int len) 1232 { 1233 buffer_append(&input, buf, len); 1234 } 1235 1236 /* Returns a character from the packet. */ 1237 1238 u_int 1239 packet_get_char(void) 1240 { 1241 char ch; 1242 1243 buffer_get(&incoming_packet, &ch, 1); 1244 return (u_char) ch; 1245 } 1246 1247 /* Returns an integer from the packet data. */ 1248 1249 u_int 1250 packet_get_int(void) 1251 { 1252 return buffer_get_int(&incoming_packet); 1253 } 1254 1255 /* 1256 * Returns an arbitrary precision integer from the packet data. The integer 1257 * must have been initialized before this call. 1258 */ 1259 1260 void 1261 packet_get_bignum(BIGNUM * value) 1262 { 1263 buffer_get_bignum(&incoming_packet, value); 1264 } 1265 1266 void 1267 packet_get_bignum2(BIGNUM * value) 1268 { 1269 buffer_get_bignum2(&incoming_packet, value); 1270 } 1271 1272 void * 1273 packet_get_raw(u_int *length_ptr) 1274 { 1275 u_int bytes = buffer_len(&incoming_packet); 1276 1277 if (length_ptr != NULL) 1278 *length_ptr = bytes; 1279 return buffer_ptr(&incoming_packet); 1280 } 1281 1282 int 1283 packet_remaining(void) 1284 { 1285 return buffer_len(&incoming_packet); 1286 } 1287 1288 /* 1289 * Returns a string from the packet data. The string is allocated using 1290 * xmalloc; it is the responsibility of the calling program to free it when 1291 * no longer needed. The length_ptr argument may be NULL, or point to an 1292 * integer into which the length of the string is stored. 1293 */ 1294 1295 void * 1296 packet_get_string(u_int *length_ptr) 1297 { 1298 return buffer_get_string(&incoming_packet, length_ptr); 1299 } 1300 1301 /* 1302 * Sends a diagnostic message from the server to the client. This message 1303 * can be sent at any time (but not while constructing another message). The 1304 * message is printed immediately, but only if the client is being executed 1305 * in verbose mode. These messages are primarily intended to ease debugging 1306 * authentication problems. The length of the formatted message must not 1307 * exceed 1024 bytes. This will automatically call packet_write_wait. 1308 */ 1309 1310 void 1311 packet_send_debug(const char *fmt,...) 1312 { 1313 char buf[1024]; 1314 va_list args; 1315 1316 if (compat20 && (datafellows & SSH_BUG_DEBUG)) 1317 return; 1318 1319 va_start(args, fmt); 1320 vsnprintf(buf, sizeof(buf), fmt, args); 1321 va_end(args); 1322 1323 if (compat20) { 1324 packet_start(SSH2_MSG_DEBUG); 1325 packet_put_char(0); /* bool: always display */ 1326 packet_put_cstring(buf); 1327 packet_put_cstring(""); 1328 } else { 1329 packet_start(SSH_MSG_DEBUG); 1330 packet_put_cstring(buf); 1331 } 1332 packet_send(); 1333 packet_write_wait(); 1334 } 1335 1336 /* 1337 * Logs the error plus constructs and sends a disconnect packet, closes the 1338 * connection, and exits. This function never returns. The error message 1339 * should not contain a newline. The length of the formatted message must 1340 * not exceed 1024 bytes. 1341 */ 1342 1343 void 1344 packet_disconnect(const char *fmt,...) 1345 { 1346 char buf[1024]; 1347 va_list args; 1348 static int disconnecting = 0; 1349 1350 if (disconnecting) /* Guard against recursive invocations. */ 1351 fatal("packet_disconnect called recursively."); 1352 disconnecting = 1; 1353 1354 /* 1355 * Format the message. Note that the caller must make sure the 1356 * message is of limited size. 1357 */ 1358 va_start(args, fmt); 1359 vsnprintf(buf, sizeof(buf), fmt, args); 1360 va_end(args); 1361 1362 /* Display the error locally */ 1363 logit("Disconnecting: %.100s", buf); 1364 1365 /* Send the disconnect message to the other side, and wait for it to get sent. */ 1366 if (compat20) { 1367 packet_start(SSH2_MSG_DISCONNECT); 1368 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); 1369 packet_put_cstring(buf); 1370 packet_put_cstring(""); 1371 } else { 1372 packet_start(SSH_MSG_DISCONNECT); 1373 packet_put_cstring(buf); 1374 } 1375 packet_send(); 1376 packet_write_wait(); 1377 1378 /* Stop listening for connections. */ 1379 channel_close_all(); 1380 1381 /* Close the connection. */ 1382 packet_close(); 1383 cleanup_exit(255); 1384 } 1385 1386 /* Checks if there is any buffered output, and tries to write some of the output. */ 1387 1388 void 1389 packet_write_poll(void) 1390 { 1391 int len = buffer_len(&output); 1392 1393 if (len > 0) { 1394 len = write(connection_out, buffer_ptr(&output), len); 1395 if (len <= 0) { 1396 if (errno == EAGAIN) 1397 return; 1398 else 1399 fatal("Write failed: %.100s", strerror(errno)); 1400 } 1401 buffer_consume(&output, len); 1402 } 1403 } 1404 1405 /* 1406 * Calls packet_write_poll repeatedly until all pending output data has been 1407 * written. 1408 */ 1409 1410 void 1411 packet_write_wait(void) 1412 { 1413 fd_set *setp; 1414 1415 setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * 1416 sizeof(fd_mask)); 1417 packet_write_poll(); 1418 while (packet_have_data_to_write()) { 1419 memset(setp, 0, howmany(connection_out + 1, NFDBITS) * 1420 sizeof(fd_mask)); 1421 FD_SET(connection_out, setp); 1422 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && 1423 (errno == EAGAIN || errno == EINTR)) 1424 ; 1425 packet_write_poll(); 1426 } 1427 xfree(setp); 1428 } 1429 1430 /* Returns true if there is buffered data to write to the connection. */ 1431 1432 int 1433 packet_have_data_to_write(void) 1434 { 1435 return buffer_len(&output) != 0; 1436 } 1437 1438 /* Returns true if there is not too much data to write to the connection. */ 1439 1440 int 1441 packet_not_very_much_data_to_write(void) 1442 { 1443 if (interactive_mode) 1444 return buffer_len(&output) < 16384; 1445 else 1446 return buffer_len(&output) < 128 * 1024; 1447 } 1448 1449 1450 static void 1451 packet_set_tos(int interactive) 1452 { 1453 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) 1454 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; 1455 1456 if (!packet_connection_is_on_socket() || 1457 !packet_connection_is_ipv4()) 1458 return; 1459 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, 1460 sizeof(tos)) < 0) 1461 error("setsockopt IP_TOS %d: %.100s:", 1462 tos, strerror(errno)); 1463 #endif 1464 } 1465 1466 /* Informs that the current session is interactive. Sets IP flags for that. */ 1467 1468 void 1469 packet_set_interactive(int interactive) 1470 { 1471 static int called = 0; 1472 1473 if (called) 1474 return; 1475 called = 1; 1476 1477 /* Record that we are in interactive mode. */ 1478 interactive_mode = interactive; 1479 1480 /* Only set socket options if using a socket. */ 1481 if (!packet_connection_is_on_socket()) 1482 return; 1483 if (interactive) 1484 set_nodelay(connection_in); 1485 packet_set_tos(interactive); 1486 } 1487 1488 /* Returns true if the current connection is interactive. */ 1489 1490 int 1491 packet_is_interactive(void) 1492 { 1493 return interactive_mode; 1494 } 1495 1496 int 1497 packet_set_maxsize(u_int s) 1498 { 1499 static int called = 0; 1500 1501 if (called) { 1502 logit("packet_set_maxsize: called twice: old %d new %d", 1503 max_packet_size, s); 1504 return -1; 1505 } 1506 if (s < 4 * 1024 || s > 1024 * 1024) { 1507 logit("packet_set_maxsize: bad size %d", s); 1508 return -1; 1509 } 1510 called = 1; 1511 debug("packet_set_maxsize: setting to %d", s); 1512 max_packet_size = s; 1513 return s; 1514 } 1515 1516 /* roundup current message to pad bytes */ 1517 void 1518 packet_add_padding(u_char pad) 1519 { 1520 extra_pad = pad; 1521 } 1522 1523 /* 1524 * 9.2. Ignored Data Message 1525 * 1526 * byte SSH_MSG_IGNORE 1527 * string data 1528 * 1529 * All implementations MUST understand (and ignore) this message at any 1530 * time (after receiving the protocol version). No implementation is 1531 * required to send them. This message can be used as an additional 1532 * protection measure against advanced traffic analysis techniques. 1533 */ 1534 void 1535 packet_send_ignore(int nbytes) 1536 { 1537 u_int32_t rnd = 0; 1538 int i; 1539 1540 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); 1541 packet_put_int(nbytes); 1542 for (i = 0; i < nbytes; i++) { 1543 if (i % 4 == 0) 1544 rnd = arc4random(); 1545 packet_put_char(rnd & 0xff); 1546 rnd >>= 8; 1547 } 1548 } 1549 1550 #define MAX_PACKETS (1U<<31) 1551 int 1552 packet_need_rekeying(void) 1553 { 1554 if (datafellows & SSH_BUG_NOREKEY) 1555 return 0; 1556 return 1557 (p_send.packets > MAX_PACKETS) || 1558 (p_read.packets > MAX_PACKETS) || 1559 (max_blocks_out && (p_send.blocks > max_blocks_out)) || 1560 (max_blocks_in && (p_read.blocks > max_blocks_in)); 1561 } 1562 1563 void 1564 packet_set_rekey_limit(u_int32_t bytes) 1565 { 1566 rekey_limit = bytes; 1567 } 1568 1569 void 1570 packet_set_server(void) 1571 { 1572 server_side = 1; 1573 } 1574 1575 void 1576 packet_set_authenticated(void) 1577 { 1578 after_authentication = 1; 1579 } 1580