1 /* $OpenBSD: packet.c,v 1.157 2008/07/10 18:08:11 markus Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This file contains code implementing the packet protocol and communication 7 * with the other side. This same code is used both on client and server side. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 * 15 * 16 * SSH2 packet format added by Markus Friedl. 17 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 18 * 19 * Redistribution and use in source and binary forms, with or without 20 * modification, are permitted provided that the following conditions 21 * are met: 22 * 1. Redistributions of source code must retain the above copyright 23 * notice, this list of conditions and the following disclaimer. 24 * 2. Redistributions in binary form must reproduce the above copyright 25 * notice, this list of conditions and the following disclaimer in the 26 * documentation and/or other materials provided with the distribution. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40 #include "includes.h" 41 42 #include <sys/types.h> 43 #include "openbsd-compat/sys-queue.h" 44 #include <sys/param.h> 45 #include <sys/socket.h> 46 #ifdef HAVE_SYS_TIME_H 47 # include <sys/time.h> 48 #endif 49 50 #include <netinet/in.h> 51 #include <netinet/ip.h> 52 #include <arpa/inet.h> 53 54 #include <errno.h> 55 #include <stdarg.h> 56 #include <stdio.h> 57 #include <stdlib.h> 58 #include <string.h> 59 #include <unistd.h> 60 #include <signal.h> 61 62 #include "xmalloc.h" 63 #include "buffer.h" 64 #include "packet.h" 65 #include "crc32.h" 66 #include "compress.h" 67 #include "deattack.h" 68 #include "channels.h" 69 #include "compat.h" 70 #include "ssh1.h" 71 #include "ssh2.h" 72 #include "cipher.h" 73 #include "key.h" 74 #include "kex.h" 75 #include "mac.h" 76 #include "log.h" 77 #include "canohost.h" 78 #include "misc.h" 79 #include "ssh.h" 80 81 #ifdef PACKET_DEBUG 82 #define DBG(x) x 83 #else 84 #define DBG(x) 85 #endif 86 87 /* 88 * This variable contains the file descriptors used for communicating with 89 * the other side. connection_in is used for reading; connection_out for 90 * writing. These can be the same descriptor, in which case it is assumed to 91 * be a socket. 92 */ 93 static int connection_in = -1; 94 static int connection_out = -1; 95 96 /* Protocol flags for the remote side. */ 97 static u_int remote_protocol_flags = 0; 98 99 /* Encryption context for receiving data. This is only used for decryption. */ 100 static CipherContext receive_context; 101 102 /* Encryption context for sending data. This is only used for encryption. */ 103 static CipherContext send_context; 104 105 /* Buffer for raw input data from the socket. */ 106 Buffer input; 107 108 /* Buffer for raw output data going to the socket. */ 109 Buffer output; 110 111 /* Buffer for the partial outgoing packet being constructed. */ 112 static Buffer outgoing_packet; 113 114 /* Buffer for the incoming packet currently being processed. */ 115 static Buffer incoming_packet; 116 117 /* Scratch buffer for packet compression/decompression. */ 118 static Buffer compression_buffer; 119 static int compression_buffer_ready = 0; 120 121 /* Flag indicating whether packet compression/decompression is enabled. */ 122 static int packet_compression = 0; 123 124 /* default maximum packet size */ 125 u_int max_packet_size = 32768; 126 127 /* Flag indicating whether this module has been initialized. */ 128 static int initialized = 0; 129 130 /* Set to true if the connection is interactive. */ 131 static int interactive_mode = 0; 132 133 /* Set to true if we are the server side. */ 134 static int server_side = 0; 135 136 /* Set to true if we are authenticated. */ 137 static int after_authentication = 0; 138 139 int keep_alive_timeouts = 0; 140 141 /* Set to the maximum time that we will wait to send or receive a packet */ 142 static int packet_timeout_ms = -1; 143 144 /* Session key information for Encryption and MAC */ 145 Newkeys *newkeys[MODE_MAX]; 146 static struct packet_state { 147 u_int32_t seqnr; 148 u_int32_t packets; 149 u_int64_t blocks; 150 u_int64_t bytes; 151 } p_read, p_send; 152 153 static u_int64_t max_blocks_in, max_blocks_out; 154 static u_int32_t rekey_limit; 155 156 /* Session key for protocol v1 */ 157 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; 158 static u_int ssh1_keylen; 159 160 /* roundup current message to extra_pad bytes */ 161 static u_char extra_pad = 0; 162 163 struct packet { 164 TAILQ_ENTRY(packet) next; 165 u_char type; 166 Buffer payload; 167 }; 168 TAILQ_HEAD(, packet) outgoing; 169 170 /* 171 * Sets the descriptors used for communication. Disables encryption until 172 * packet_set_encryption_key is called. 173 */ 174 void 175 packet_set_connection(int fd_in, int fd_out) 176 { 177 Cipher *none = cipher_by_name("none"); 178 179 if (none == NULL) 180 fatal("packet_set_connection: cannot load cipher 'none'"); 181 connection_in = fd_in; 182 connection_out = fd_out; 183 cipher_init(&send_context, none, (const u_char *)"", 184 0, NULL, 0, CIPHER_ENCRYPT); 185 cipher_init(&receive_context, none, (const u_char *)"", 186 0, NULL, 0, CIPHER_DECRYPT); 187 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; 188 if (!initialized) { 189 initialized = 1; 190 buffer_init(&input); 191 buffer_init(&output); 192 buffer_init(&outgoing_packet); 193 buffer_init(&incoming_packet); 194 TAILQ_INIT(&outgoing); 195 p_send.packets = p_read.packets = 0; 196 } 197 } 198 199 void 200 packet_set_timeout(int timeout, int count) 201 { 202 if (timeout == 0 || count == 0) { 203 packet_timeout_ms = -1; 204 return; 205 } 206 if ((INT_MAX / 1000) / count < timeout) 207 packet_timeout_ms = INT_MAX; 208 else 209 packet_timeout_ms = timeout * count * 1000; 210 } 211 212 /* Returns 1 if remote host is connected via socket, 0 if not. */ 213 214 int 215 packet_connection_is_on_socket(void) 216 { 217 struct sockaddr_storage from, to; 218 socklen_t fromlen, tolen; 219 220 /* filedescriptors in and out are the same, so it's a socket */ 221 if (connection_in == connection_out) 222 return 1; 223 fromlen = sizeof(from); 224 memset(&from, 0, sizeof(from)); 225 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) 226 return 0; 227 tolen = sizeof(to); 228 memset(&to, 0, sizeof(to)); 229 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) 230 return 0; 231 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) 232 return 0; 233 if (from.ss_family != AF_INET && from.ss_family != AF_INET6) 234 return 0; 235 return 1; 236 } 237 238 /* 239 * Exports an IV from the CipherContext required to export the key 240 * state back from the unprivileged child to the privileged parent 241 * process. 242 */ 243 244 void 245 packet_get_keyiv(int mode, u_char *iv, u_int len) 246 { 247 CipherContext *cc; 248 249 if (mode == MODE_OUT) 250 cc = &send_context; 251 else 252 cc = &receive_context; 253 254 cipher_get_keyiv(cc, iv, len); 255 } 256 257 int 258 packet_get_keycontext(int mode, u_char *dat) 259 { 260 CipherContext *cc; 261 262 if (mode == MODE_OUT) 263 cc = &send_context; 264 else 265 cc = &receive_context; 266 267 return (cipher_get_keycontext(cc, dat)); 268 } 269 270 void 271 packet_set_keycontext(int mode, u_char *dat) 272 { 273 CipherContext *cc; 274 275 if (mode == MODE_OUT) 276 cc = &send_context; 277 else 278 cc = &receive_context; 279 280 cipher_set_keycontext(cc, dat); 281 } 282 283 int 284 packet_get_keyiv_len(int mode) 285 { 286 CipherContext *cc; 287 288 if (mode == MODE_OUT) 289 cc = &send_context; 290 else 291 cc = &receive_context; 292 293 return (cipher_get_keyiv_len(cc)); 294 } 295 296 void 297 packet_set_iv(int mode, u_char *dat) 298 { 299 CipherContext *cc; 300 301 if (mode == MODE_OUT) 302 cc = &send_context; 303 else 304 cc = &receive_context; 305 306 cipher_set_keyiv(cc, dat); 307 } 308 309 int 310 packet_get_ssh1_cipher(void) 311 { 312 return (cipher_get_number(receive_context.cipher)); 313 } 314 315 void 316 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets, 317 u_int64_t *bytes) 318 { 319 struct packet_state *state; 320 321 state = (mode == MODE_IN) ? &p_read : &p_send; 322 if (seqnr) 323 *seqnr = state->seqnr; 324 if (blocks) 325 *blocks = state->blocks; 326 if (packets) 327 *packets = state->packets; 328 if (bytes) 329 *bytes = state->bytes; 330 } 331 332 void 333 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets, 334 u_int64_t bytes) 335 { 336 struct packet_state *state; 337 338 state = (mode == MODE_IN) ? &p_read : &p_send; 339 state->seqnr = seqnr; 340 state->blocks = blocks; 341 state->packets = packets; 342 state->bytes = bytes; 343 } 344 345 /* returns 1 if connection is via ipv4 */ 346 347 int 348 packet_connection_is_ipv4(void) 349 { 350 struct sockaddr_storage to; 351 socklen_t tolen = sizeof(to); 352 353 memset(&to, 0, sizeof(to)); 354 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) 355 return 0; 356 if (to.ss_family == AF_INET) 357 return 1; 358 #ifdef IPV4_IN_IPV6 359 if (to.ss_family == AF_INET6 && 360 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) 361 return 1; 362 #endif 363 return 0; 364 } 365 366 /* Sets the connection into non-blocking mode. */ 367 368 void 369 packet_set_nonblocking(void) 370 { 371 /* Set the socket into non-blocking mode. */ 372 set_nonblock(connection_in); 373 374 if (connection_out != connection_in) 375 set_nonblock(connection_out); 376 } 377 378 /* Returns the socket used for reading. */ 379 380 int 381 packet_get_connection_in(void) 382 { 383 return connection_in; 384 } 385 386 /* Returns the descriptor used for writing. */ 387 388 int 389 packet_get_connection_out(void) 390 { 391 return connection_out; 392 } 393 394 /* Closes the connection and clears and frees internal data structures. */ 395 396 void 397 packet_close(void) 398 { 399 if (!initialized) 400 return; 401 initialized = 0; 402 if (connection_in == connection_out) { 403 shutdown(connection_out, SHUT_RDWR); 404 close(connection_out); 405 } else { 406 close(connection_in); 407 close(connection_out); 408 } 409 buffer_free(&input); 410 buffer_free(&output); 411 buffer_free(&outgoing_packet); 412 buffer_free(&incoming_packet); 413 if (compression_buffer_ready) { 414 buffer_free(&compression_buffer); 415 buffer_compress_uninit(); 416 } 417 cipher_cleanup(&send_context); 418 cipher_cleanup(&receive_context); 419 } 420 421 /* Sets remote side protocol flags. */ 422 423 void 424 packet_set_protocol_flags(u_int protocol_flags) 425 { 426 remote_protocol_flags = protocol_flags; 427 } 428 429 /* Returns the remote protocol flags set earlier by the above function. */ 430 431 u_int 432 packet_get_protocol_flags(void) 433 { 434 return remote_protocol_flags; 435 } 436 437 /* 438 * Starts packet compression from the next packet on in both directions. 439 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. 440 */ 441 442 static void 443 packet_init_compression(void) 444 { 445 if (compression_buffer_ready == 1) 446 return; 447 compression_buffer_ready = 1; 448 buffer_init(&compression_buffer); 449 } 450 451 void 452 packet_start_compression(int level) 453 { 454 if (packet_compression && !compat20) 455 fatal("Compression already enabled."); 456 packet_compression = 1; 457 packet_init_compression(); 458 buffer_compress_init_send(level); 459 buffer_compress_init_recv(); 460 } 461 462 /* 463 * Causes any further packets to be encrypted using the given key. The same 464 * key is used for both sending and reception. However, both directions are 465 * encrypted independently of each other. 466 */ 467 468 void 469 packet_set_encryption_key(const u_char *key, u_int keylen, 470 int number) 471 { 472 Cipher *cipher = cipher_by_number(number); 473 474 if (cipher == NULL) 475 fatal("packet_set_encryption_key: unknown cipher number %d", number); 476 if (keylen < 20) 477 fatal("packet_set_encryption_key: keylen too small: %d", keylen); 478 if (keylen > SSH_SESSION_KEY_LENGTH) 479 fatal("packet_set_encryption_key: keylen too big: %d", keylen); 480 memcpy(ssh1_key, key, keylen); 481 ssh1_keylen = keylen; 482 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); 483 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); 484 } 485 486 u_int 487 packet_get_encryption_key(u_char *key) 488 { 489 if (key == NULL) 490 return (ssh1_keylen); 491 memcpy(key, ssh1_key, ssh1_keylen); 492 return (ssh1_keylen); 493 } 494 495 /* Start constructing a packet to send. */ 496 void 497 packet_start(u_char type) 498 { 499 u_char buf[9]; 500 int len; 501 502 DBG(debug("packet_start[%d]", type)); 503 len = compat20 ? 6 : 9; 504 memset(buf, 0, len - 1); 505 buf[len - 1] = type; 506 buffer_clear(&outgoing_packet); 507 buffer_append(&outgoing_packet, buf, len); 508 } 509 510 /* Append payload. */ 511 void 512 packet_put_char(int value) 513 { 514 char ch = value; 515 516 buffer_append(&outgoing_packet, &ch, 1); 517 } 518 519 void 520 packet_put_int(u_int value) 521 { 522 buffer_put_int(&outgoing_packet, value); 523 } 524 525 void 526 packet_put_string(const void *buf, u_int len) 527 { 528 buffer_put_string(&outgoing_packet, buf, len); 529 } 530 531 void 532 packet_put_cstring(const char *str) 533 { 534 buffer_put_cstring(&outgoing_packet, str); 535 } 536 537 void 538 packet_put_raw(const void *buf, u_int len) 539 { 540 buffer_append(&outgoing_packet, buf, len); 541 } 542 543 void 544 packet_put_bignum(BIGNUM * value) 545 { 546 buffer_put_bignum(&outgoing_packet, value); 547 } 548 549 void 550 packet_put_bignum2(BIGNUM * value) 551 { 552 buffer_put_bignum2(&outgoing_packet, value); 553 } 554 555 /* 556 * Finalizes and sends the packet. If the encryption key has been set, 557 * encrypts the packet before sending. 558 */ 559 560 static void 561 packet_send1(void) 562 { 563 u_char buf[8], *cp; 564 int i, padding, len; 565 u_int checksum; 566 u_int32_t rnd = 0; 567 568 /* 569 * If using packet compression, compress the payload of the outgoing 570 * packet. 571 */ 572 if (packet_compression) { 573 buffer_clear(&compression_buffer); 574 /* Skip padding. */ 575 buffer_consume(&outgoing_packet, 8); 576 /* padding */ 577 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); 578 buffer_compress(&outgoing_packet, &compression_buffer); 579 buffer_clear(&outgoing_packet); 580 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 581 buffer_len(&compression_buffer)); 582 } 583 /* Compute packet length without padding (add checksum, remove padding). */ 584 len = buffer_len(&outgoing_packet) + 4 - 8; 585 586 /* Insert padding. Initialized to zero in packet_start1() */ 587 padding = 8 - len % 8; 588 if (!send_context.plaintext) { 589 cp = buffer_ptr(&outgoing_packet); 590 for (i = 0; i < padding; i++) { 591 if (i % 4 == 0) 592 rnd = arc4random(); 593 cp[7 - i] = rnd & 0xff; 594 rnd >>= 8; 595 } 596 } 597 buffer_consume(&outgoing_packet, 8 - padding); 598 599 /* Add check bytes. */ 600 checksum = ssh_crc32(buffer_ptr(&outgoing_packet), 601 buffer_len(&outgoing_packet)); 602 put_u32(buf, checksum); 603 buffer_append(&outgoing_packet, buf, 4); 604 605 #ifdef PACKET_DEBUG 606 fprintf(stderr, "packet_send plain: "); 607 buffer_dump(&outgoing_packet); 608 #endif 609 610 /* Append to output. */ 611 put_u32(buf, len); 612 buffer_append(&output, buf, 4); 613 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 614 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 615 buffer_len(&outgoing_packet)); 616 617 #ifdef PACKET_DEBUG 618 fprintf(stderr, "encrypted: "); 619 buffer_dump(&output); 620 #endif 621 p_send.packets++; 622 p_send.bytes += len + buffer_len(&outgoing_packet); 623 buffer_clear(&outgoing_packet); 624 625 /* 626 * Note that the packet is now only buffered in output. It won't be 627 * actually sent until packet_write_wait or packet_write_poll is 628 * called. 629 */ 630 } 631 632 void 633 set_newkeys(int mode) 634 { 635 Enc *enc; 636 Mac *mac; 637 Comp *comp; 638 CipherContext *cc; 639 u_int64_t *max_blocks; 640 int crypt_type; 641 642 debug2("set_newkeys: mode %d", mode); 643 644 if (mode == MODE_OUT) { 645 cc = &send_context; 646 crypt_type = CIPHER_ENCRYPT; 647 p_send.packets = p_send.blocks = 0; 648 max_blocks = &max_blocks_out; 649 } else { 650 cc = &receive_context; 651 crypt_type = CIPHER_DECRYPT; 652 p_read.packets = p_read.blocks = 0; 653 max_blocks = &max_blocks_in; 654 } 655 if (newkeys[mode] != NULL) { 656 debug("set_newkeys: rekeying"); 657 cipher_cleanup(cc); 658 enc = &newkeys[mode]->enc; 659 mac = &newkeys[mode]->mac; 660 comp = &newkeys[mode]->comp; 661 mac_clear(mac); 662 xfree(enc->name); 663 xfree(enc->iv); 664 xfree(enc->key); 665 xfree(mac->name); 666 xfree(mac->key); 667 xfree(comp->name); 668 xfree(newkeys[mode]); 669 } 670 newkeys[mode] = kex_get_newkeys(mode); 671 if (newkeys[mode] == NULL) 672 fatal("newkeys: no keys for mode %d", mode); 673 enc = &newkeys[mode]->enc; 674 mac = &newkeys[mode]->mac; 675 comp = &newkeys[mode]->comp; 676 if (mac_init(mac) == 0) 677 mac->enabled = 1; 678 DBG(debug("cipher_init_context: %d", mode)); 679 cipher_init(cc, enc->cipher, enc->key, enc->key_len, 680 enc->iv, enc->block_size, crypt_type); 681 /* Deleting the keys does not gain extra security */ 682 /* memset(enc->iv, 0, enc->block_size); 683 memset(enc->key, 0, enc->key_len); 684 memset(mac->key, 0, mac->key_len); */ 685 if ((comp->type == COMP_ZLIB || 686 (comp->type == COMP_DELAYED && after_authentication)) && 687 comp->enabled == 0) { 688 packet_init_compression(); 689 if (mode == MODE_OUT) 690 buffer_compress_init_send(6); 691 else 692 buffer_compress_init_recv(); 693 comp->enabled = 1; 694 } 695 /* 696 * The 2^(blocksize*2) limit is too expensive for 3DES, 697 * blowfish, etc, so enforce a 1GB limit for small blocksizes. 698 */ 699 if (enc->block_size >= 16) 700 *max_blocks = (u_int64_t)1 << (enc->block_size*2); 701 else 702 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; 703 if (rekey_limit) 704 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); 705 } 706 707 /* 708 * Delayed compression for SSH2 is enabled after authentication: 709 * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent, 710 * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received. 711 */ 712 static void 713 packet_enable_delayed_compress(void) 714 { 715 Comp *comp = NULL; 716 int mode; 717 718 /* 719 * Remember that we are past the authentication step, so rekeying 720 * with COMP_DELAYED will turn on compression immediately. 721 */ 722 after_authentication = 1; 723 for (mode = 0; mode < MODE_MAX; mode++) { 724 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */ 725 if (newkeys[mode] == NULL) 726 continue; 727 comp = &newkeys[mode]->comp; 728 if (comp && !comp->enabled && comp->type == COMP_DELAYED) { 729 packet_init_compression(); 730 if (mode == MODE_OUT) 731 buffer_compress_init_send(6); 732 else 733 buffer_compress_init_recv(); 734 comp->enabled = 1; 735 } 736 } 737 } 738 739 /* 740 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) 741 */ 742 static void 743 packet_send2_wrapped(void) 744 { 745 u_char type, *cp, *macbuf = NULL; 746 u_char padlen, pad; 747 u_int packet_length = 0; 748 u_int i, len; 749 u_int32_t rnd = 0; 750 Enc *enc = NULL; 751 Mac *mac = NULL; 752 Comp *comp = NULL; 753 int block_size; 754 755 if (newkeys[MODE_OUT] != NULL) { 756 enc = &newkeys[MODE_OUT]->enc; 757 mac = &newkeys[MODE_OUT]->mac; 758 comp = &newkeys[MODE_OUT]->comp; 759 } 760 block_size = enc ? enc->block_size : 8; 761 762 cp = buffer_ptr(&outgoing_packet); 763 type = cp[5]; 764 765 #ifdef PACKET_DEBUG 766 fprintf(stderr, "plain: "); 767 buffer_dump(&outgoing_packet); 768 #endif 769 770 if (comp && comp->enabled) { 771 len = buffer_len(&outgoing_packet); 772 /* skip header, compress only payload */ 773 buffer_consume(&outgoing_packet, 5); 774 buffer_clear(&compression_buffer); 775 buffer_compress(&outgoing_packet, &compression_buffer); 776 buffer_clear(&outgoing_packet); 777 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); 778 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 779 buffer_len(&compression_buffer)); 780 DBG(debug("compression: raw %d compressed %d", len, 781 buffer_len(&outgoing_packet))); 782 } 783 784 /* sizeof (packet_len + pad_len + payload) */ 785 len = buffer_len(&outgoing_packet); 786 787 /* 788 * calc size of padding, alloc space, get random data, 789 * minimum padding is 4 bytes 790 */ 791 padlen = block_size - (len % block_size); 792 if (padlen < 4) 793 padlen += block_size; 794 if (extra_pad) { 795 /* will wrap if extra_pad+padlen > 255 */ 796 extra_pad = roundup(extra_pad, block_size); 797 pad = extra_pad - ((len + padlen) % extra_pad); 798 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", 799 pad, len, padlen, extra_pad); 800 padlen += pad; 801 extra_pad = 0; 802 } 803 cp = buffer_append_space(&outgoing_packet, padlen); 804 if (enc && !send_context.plaintext) { 805 /* random padding */ 806 for (i = 0; i < padlen; i++) { 807 if (i % 4 == 0) 808 rnd = arc4random(); 809 cp[i] = rnd & 0xff; 810 rnd >>= 8; 811 } 812 } else { 813 /* clear padding */ 814 memset(cp, 0, padlen); 815 } 816 /* packet_length includes payload, padding and padding length field */ 817 packet_length = buffer_len(&outgoing_packet) - 4; 818 cp = buffer_ptr(&outgoing_packet); 819 put_u32(cp, packet_length); 820 cp[4] = padlen; 821 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); 822 823 /* compute MAC over seqnr and packet(length fields, payload, padding) */ 824 if (mac && mac->enabled) { 825 macbuf = mac_compute(mac, p_send.seqnr, 826 buffer_ptr(&outgoing_packet), 827 buffer_len(&outgoing_packet)); 828 DBG(debug("done calc MAC out #%d", p_send.seqnr)); 829 } 830 /* encrypt packet and append to output buffer. */ 831 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 832 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 833 buffer_len(&outgoing_packet)); 834 /* append unencrypted MAC */ 835 if (mac && mac->enabled) 836 buffer_append(&output, macbuf, mac->mac_len); 837 #ifdef PACKET_DEBUG 838 fprintf(stderr, "encrypted: "); 839 buffer_dump(&output); 840 #endif 841 /* increment sequence number for outgoing packets */ 842 if (++p_send.seqnr == 0) 843 logit("outgoing seqnr wraps around"); 844 if (++p_send.packets == 0) 845 if (!(datafellows & SSH_BUG_NOREKEY)) 846 fatal("XXX too many packets with same key"); 847 p_send.blocks += (packet_length + 4) / block_size; 848 p_send.bytes += packet_length + 4; 849 buffer_clear(&outgoing_packet); 850 851 if (type == SSH2_MSG_NEWKEYS) 852 set_newkeys(MODE_OUT); 853 else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side) 854 packet_enable_delayed_compress(); 855 } 856 857 static void 858 packet_send2(void) 859 { 860 static int rekeying = 0; 861 struct packet *p; 862 u_char type, *cp; 863 864 cp = buffer_ptr(&outgoing_packet); 865 type = cp[5]; 866 867 /* during rekeying we can only send key exchange messages */ 868 if (rekeying) { 869 if (!((type >= SSH2_MSG_TRANSPORT_MIN) && 870 (type <= SSH2_MSG_TRANSPORT_MAX))) { 871 debug("enqueue packet: %u", type); 872 p = xmalloc(sizeof(*p)); 873 p->type = type; 874 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); 875 buffer_init(&outgoing_packet); 876 TAILQ_INSERT_TAIL(&outgoing, p, next); 877 return; 878 } 879 } 880 881 /* rekeying starts with sending KEXINIT */ 882 if (type == SSH2_MSG_KEXINIT) 883 rekeying = 1; 884 885 packet_send2_wrapped(); 886 887 /* after a NEWKEYS message we can send the complete queue */ 888 if (type == SSH2_MSG_NEWKEYS) { 889 rekeying = 0; 890 while ((p = TAILQ_FIRST(&outgoing))) { 891 type = p->type; 892 debug("dequeue packet: %u", type); 893 buffer_free(&outgoing_packet); 894 memcpy(&outgoing_packet, &p->payload, 895 sizeof(Buffer)); 896 TAILQ_REMOVE(&outgoing, p, next); 897 xfree(p); 898 packet_send2_wrapped(); 899 } 900 } 901 } 902 903 void 904 packet_send(void) 905 { 906 if (compat20) 907 packet_send2(); 908 else 909 packet_send1(); 910 DBG(debug("packet_send done")); 911 } 912 913 /* 914 * Waits until a packet has been received, and returns its type. Note that 915 * no other data is processed until this returns, so this function should not 916 * be used during the interactive session. 917 */ 918 919 int 920 packet_read_seqnr(u_int32_t *seqnr_p) 921 { 922 int type, len, ret, ms_remain; 923 fd_set *setp; 924 char buf[8192]; 925 struct timeval timeout, start, *timeoutp = NULL; 926 927 DBG(debug("packet_read()")); 928 929 setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS), 930 sizeof(fd_mask)); 931 932 /* Since we are blocking, ensure that all written packets have been sent. */ 933 packet_write_wait(); 934 935 /* Stay in the loop until we have received a complete packet. */ 936 for (;;) { 937 /* Try to read a packet from the buffer. */ 938 type = packet_read_poll_seqnr(seqnr_p); 939 if (!compat20 && ( 940 type == SSH_SMSG_SUCCESS 941 || type == SSH_SMSG_FAILURE 942 || type == SSH_CMSG_EOF 943 || type == SSH_CMSG_EXIT_CONFIRMATION)) 944 packet_check_eom(); 945 /* If we got a packet, return it. */ 946 if (type != SSH_MSG_NONE) { 947 xfree(setp); 948 return type; 949 } 950 /* 951 * Otherwise, wait for some data to arrive, add it to the 952 * buffer, and try again. 953 */ 954 memset(setp, 0, howmany(connection_in + 1, NFDBITS) * 955 sizeof(fd_mask)); 956 FD_SET(connection_in, setp); 957 958 if (packet_timeout_ms > 0) { 959 ms_remain = packet_timeout_ms; 960 timeoutp = &timeout; 961 } 962 /* Wait for some data to arrive. */ 963 for (;;) { 964 if (packet_timeout_ms != -1) { 965 ms_to_timeval(&timeout, ms_remain); 966 gettimeofday(&start, NULL); 967 } 968 if ((ret = select(connection_in + 1, setp, NULL, 969 NULL, timeoutp)) >= 0) 970 break; 971 if (errno != EAGAIN && errno != EINTR && 972 errno != EWOULDBLOCK) 973 break; 974 if (packet_timeout_ms == -1) 975 continue; 976 ms_subtract_diff(&start, &ms_remain); 977 if (ms_remain <= 0) { 978 ret = 0; 979 break; 980 } 981 } 982 if (ret == 0) { 983 logit("Connection to %.200s timed out while " 984 "waiting to read", get_remote_ipaddr()); 985 cleanup_exit(255); 986 } 987 /* Read data from the socket. */ 988 len = read(connection_in, buf, sizeof(buf)); 989 if (len == 0) { 990 logit("Connection closed by %.200s", get_remote_ipaddr()); 991 cleanup_exit(255); 992 } 993 if (len < 0) 994 fatal("Read from socket failed: %.100s", strerror(errno)); 995 /* Append it to the buffer. */ 996 packet_process_incoming(buf, len); 997 } 998 /* NOTREACHED */ 999 } 1000 1001 int 1002 packet_read(void) 1003 { 1004 return packet_read_seqnr(NULL); 1005 } 1006 1007 /* 1008 * Waits until a packet has been received, verifies that its type matches 1009 * that given, and gives a fatal error and exits if there is a mismatch. 1010 */ 1011 1012 void 1013 packet_read_expect(int expected_type) 1014 { 1015 int type; 1016 1017 type = packet_read(); 1018 if (type != expected_type) 1019 packet_disconnect("Protocol error: expected packet type %d, got %d", 1020 expected_type, type); 1021 } 1022 1023 /* Checks if a full packet is available in the data received so far via 1024 * packet_process_incoming. If so, reads the packet; otherwise returns 1025 * SSH_MSG_NONE. This does not wait for data from the connection. 1026 * 1027 * SSH_MSG_DISCONNECT is handled specially here. Also, 1028 * SSH_MSG_IGNORE messages are skipped by this function and are never returned 1029 * to higher levels. 1030 */ 1031 1032 static int 1033 packet_read_poll1(void) 1034 { 1035 u_int len, padded_len; 1036 u_char *cp, type; 1037 u_int checksum, stored_checksum; 1038 1039 /* Check if input size is less than minimum packet size. */ 1040 if (buffer_len(&input) < 4 + 8) 1041 return SSH_MSG_NONE; 1042 /* Get length of incoming packet. */ 1043 cp = buffer_ptr(&input); 1044 len = get_u32(cp); 1045 if (len < 1 + 2 + 2 || len > 256 * 1024) 1046 packet_disconnect("Bad packet length %u.", len); 1047 padded_len = (len + 8) & ~7; 1048 1049 /* Check if the packet has been entirely received. */ 1050 if (buffer_len(&input) < 4 + padded_len) 1051 return SSH_MSG_NONE; 1052 1053 /* The entire packet is in buffer. */ 1054 1055 /* Consume packet length. */ 1056 buffer_consume(&input, 4); 1057 1058 /* 1059 * Cryptographic attack detector for ssh 1060 * (C)1998 CORE-SDI, Buenos Aires Argentina 1061 * Ariel Futoransky(futo@core-sdi.com) 1062 */ 1063 if (!receive_context.plaintext) { 1064 switch (detect_attack(buffer_ptr(&input), padded_len)) { 1065 case DEATTACK_DETECTED: 1066 packet_disconnect("crc32 compensation attack: " 1067 "network attack detected"); 1068 case DEATTACK_DOS_DETECTED: 1069 packet_disconnect("deattack denial of " 1070 "service detected"); 1071 } 1072 } 1073 1074 /* Decrypt data to incoming_packet. */ 1075 buffer_clear(&incoming_packet); 1076 cp = buffer_append_space(&incoming_packet, padded_len); 1077 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); 1078 1079 buffer_consume(&input, padded_len); 1080 1081 #ifdef PACKET_DEBUG 1082 fprintf(stderr, "read_poll plain: "); 1083 buffer_dump(&incoming_packet); 1084 #endif 1085 1086 /* Compute packet checksum. */ 1087 checksum = ssh_crc32(buffer_ptr(&incoming_packet), 1088 buffer_len(&incoming_packet) - 4); 1089 1090 /* Skip padding. */ 1091 buffer_consume(&incoming_packet, 8 - len % 8); 1092 1093 /* Test check bytes. */ 1094 if (len != buffer_len(&incoming_packet)) 1095 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", 1096 len, buffer_len(&incoming_packet)); 1097 1098 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; 1099 stored_checksum = get_u32(cp); 1100 if (checksum != stored_checksum) 1101 packet_disconnect("Corrupted check bytes on input."); 1102 buffer_consume_end(&incoming_packet, 4); 1103 1104 if (packet_compression) { 1105 buffer_clear(&compression_buffer); 1106 buffer_uncompress(&incoming_packet, &compression_buffer); 1107 buffer_clear(&incoming_packet); 1108 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1109 buffer_len(&compression_buffer)); 1110 } 1111 p_read.packets++; 1112 p_read.bytes += padded_len + 4; 1113 type = buffer_get_char(&incoming_packet); 1114 if (type < SSH_MSG_MIN || type > SSH_MSG_MAX) 1115 packet_disconnect("Invalid ssh1 packet type: %d", type); 1116 return type; 1117 } 1118 1119 static int 1120 packet_read_poll2(u_int32_t *seqnr_p) 1121 { 1122 static u_int packet_length = 0; 1123 u_int padlen, need; 1124 u_char *macbuf, *cp, type; 1125 u_int maclen, block_size; 1126 Enc *enc = NULL; 1127 Mac *mac = NULL; 1128 Comp *comp = NULL; 1129 1130 if (newkeys[MODE_IN] != NULL) { 1131 enc = &newkeys[MODE_IN]->enc; 1132 mac = &newkeys[MODE_IN]->mac; 1133 comp = &newkeys[MODE_IN]->comp; 1134 } 1135 maclen = mac && mac->enabled ? mac->mac_len : 0; 1136 block_size = enc ? enc->block_size : 8; 1137 1138 if (packet_length == 0) { 1139 /* 1140 * check if input size is less than the cipher block size, 1141 * decrypt first block and extract length of incoming packet 1142 */ 1143 if (buffer_len(&input) < block_size) 1144 return SSH_MSG_NONE; 1145 buffer_clear(&incoming_packet); 1146 cp = buffer_append_space(&incoming_packet, block_size); 1147 cipher_crypt(&receive_context, cp, buffer_ptr(&input), 1148 block_size); 1149 cp = buffer_ptr(&incoming_packet); 1150 packet_length = get_u32(cp); 1151 if (packet_length < 1 + 4 || packet_length > 256 * 1024) { 1152 #ifdef PACKET_DEBUG 1153 buffer_dump(&incoming_packet); 1154 #endif 1155 packet_disconnect("Bad packet length %u.", packet_length); 1156 } 1157 DBG(debug("input: packet len %u", packet_length+4)); 1158 buffer_consume(&input, block_size); 1159 } 1160 /* we have a partial packet of block_size bytes */ 1161 need = 4 + packet_length - block_size; 1162 DBG(debug("partial packet %d, need %d, maclen %d", block_size, 1163 need, maclen)); 1164 if (need % block_size != 0) 1165 fatal("padding error: need %d block %d mod %d", 1166 need, block_size, need % block_size); 1167 /* 1168 * check if the entire packet has been received and 1169 * decrypt into incoming_packet 1170 */ 1171 if (buffer_len(&input) < need + maclen) 1172 return SSH_MSG_NONE; 1173 #ifdef PACKET_DEBUG 1174 fprintf(stderr, "read_poll enc/full: "); 1175 buffer_dump(&input); 1176 #endif 1177 cp = buffer_append_space(&incoming_packet, need); 1178 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); 1179 buffer_consume(&input, need); 1180 /* 1181 * compute MAC over seqnr and packet, 1182 * increment sequence number for incoming packet 1183 */ 1184 if (mac && mac->enabled) { 1185 macbuf = mac_compute(mac, p_read.seqnr, 1186 buffer_ptr(&incoming_packet), 1187 buffer_len(&incoming_packet)); 1188 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) 1189 packet_disconnect("Corrupted MAC on input."); 1190 DBG(debug("MAC #%d ok", p_read.seqnr)); 1191 buffer_consume(&input, mac->mac_len); 1192 } 1193 if (seqnr_p != NULL) 1194 *seqnr_p = p_read.seqnr; 1195 if (++p_read.seqnr == 0) 1196 logit("incoming seqnr wraps around"); 1197 if (++p_read.packets == 0) 1198 if (!(datafellows & SSH_BUG_NOREKEY)) 1199 fatal("XXX too many packets with same key"); 1200 p_read.blocks += (packet_length + 4) / block_size; 1201 p_read.bytes += packet_length + 4; 1202 1203 /* get padlen */ 1204 cp = buffer_ptr(&incoming_packet); 1205 padlen = cp[4]; 1206 DBG(debug("input: padlen %d", padlen)); 1207 if (padlen < 4) 1208 packet_disconnect("Corrupted padlen %d on input.", padlen); 1209 1210 /* skip packet size + padlen, discard padding */ 1211 buffer_consume(&incoming_packet, 4 + 1); 1212 buffer_consume_end(&incoming_packet, padlen); 1213 1214 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); 1215 if (comp && comp->enabled) { 1216 buffer_clear(&compression_buffer); 1217 buffer_uncompress(&incoming_packet, &compression_buffer); 1218 buffer_clear(&incoming_packet); 1219 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1220 buffer_len(&compression_buffer)); 1221 DBG(debug("input: len after de-compress %d", 1222 buffer_len(&incoming_packet))); 1223 } 1224 /* 1225 * get packet type, implies consume. 1226 * return length of payload (without type field) 1227 */ 1228 type = buffer_get_char(&incoming_packet); 1229 if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN) 1230 packet_disconnect("Invalid ssh2 packet type: %d", type); 1231 if (type == SSH2_MSG_NEWKEYS) 1232 set_newkeys(MODE_IN); 1233 else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side) 1234 packet_enable_delayed_compress(); 1235 #ifdef PACKET_DEBUG 1236 fprintf(stderr, "read/plain[%d]:\r\n", type); 1237 buffer_dump(&incoming_packet); 1238 #endif 1239 /* reset for next packet */ 1240 packet_length = 0; 1241 return type; 1242 } 1243 1244 int 1245 packet_read_poll_seqnr(u_int32_t *seqnr_p) 1246 { 1247 u_int reason, seqnr; 1248 u_char type; 1249 char *msg; 1250 1251 for (;;) { 1252 if (compat20) { 1253 type = packet_read_poll2(seqnr_p); 1254 if (type) { 1255 keep_alive_timeouts = 0; 1256 DBG(debug("received packet type %d", type)); 1257 } 1258 switch (type) { 1259 case SSH2_MSG_IGNORE: 1260 debug3("Received SSH2_MSG_IGNORE"); 1261 break; 1262 case SSH2_MSG_DEBUG: 1263 packet_get_char(); 1264 msg = packet_get_string(NULL); 1265 debug("Remote: %.900s", msg); 1266 xfree(msg); 1267 msg = packet_get_string(NULL); 1268 xfree(msg); 1269 break; 1270 case SSH2_MSG_DISCONNECT: 1271 reason = packet_get_int(); 1272 msg = packet_get_string(NULL); 1273 logit("Received disconnect from %s: %u: %.400s", 1274 get_remote_ipaddr(), reason, msg); 1275 xfree(msg); 1276 cleanup_exit(255); 1277 break; 1278 case SSH2_MSG_UNIMPLEMENTED: 1279 seqnr = packet_get_int(); 1280 debug("Received SSH2_MSG_UNIMPLEMENTED for %u", 1281 seqnr); 1282 break; 1283 default: 1284 return type; 1285 } 1286 } else { 1287 type = packet_read_poll1(); 1288 switch (type) { 1289 case SSH_MSG_IGNORE: 1290 break; 1291 case SSH_MSG_DEBUG: 1292 msg = packet_get_string(NULL); 1293 debug("Remote: %.900s", msg); 1294 xfree(msg); 1295 break; 1296 case SSH_MSG_DISCONNECT: 1297 msg = packet_get_string(NULL); 1298 logit("Received disconnect from %s: %.400s", 1299 get_remote_ipaddr(), msg); 1300 cleanup_exit(255); 1301 break; 1302 default: 1303 if (type) 1304 DBG(debug("received packet type %d", type)); 1305 return type; 1306 } 1307 } 1308 } 1309 } 1310 1311 int 1312 packet_read_poll(void) 1313 { 1314 return packet_read_poll_seqnr(NULL); 1315 } 1316 1317 /* 1318 * Buffers the given amount of input characters. This is intended to be used 1319 * together with packet_read_poll. 1320 */ 1321 1322 void 1323 packet_process_incoming(const char *buf, u_int len) 1324 { 1325 buffer_append(&input, buf, len); 1326 } 1327 1328 /* Returns a character from the packet. */ 1329 1330 u_int 1331 packet_get_char(void) 1332 { 1333 char ch; 1334 1335 buffer_get(&incoming_packet, &ch, 1); 1336 return (u_char) ch; 1337 } 1338 1339 /* Returns an integer from the packet data. */ 1340 1341 u_int 1342 packet_get_int(void) 1343 { 1344 return buffer_get_int(&incoming_packet); 1345 } 1346 1347 /* 1348 * Returns an arbitrary precision integer from the packet data. The integer 1349 * must have been initialized before this call. 1350 */ 1351 1352 void 1353 packet_get_bignum(BIGNUM * value) 1354 { 1355 buffer_get_bignum(&incoming_packet, value); 1356 } 1357 1358 void 1359 packet_get_bignum2(BIGNUM * value) 1360 { 1361 buffer_get_bignum2(&incoming_packet, value); 1362 } 1363 1364 void * 1365 packet_get_raw(u_int *length_ptr) 1366 { 1367 u_int bytes = buffer_len(&incoming_packet); 1368 1369 if (length_ptr != NULL) 1370 *length_ptr = bytes; 1371 return buffer_ptr(&incoming_packet); 1372 } 1373 1374 int 1375 packet_remaining(void) 1376 { 1377 return buffer_len(&incoming_packet); 1378 } 1379 1380 /* 1381 * Returns a string from the packet data. The string is allocated using 1382 * xmalloc; it is the responsibility of the calling program to free it when 1383 * no longer needed. The length_ptr argument may be NULL, or point to an 1384 * integer into which the length of the string is stored. 1385 */ 1386 1387 void * 1388 packet_get_string(u_int *length_ptr) 1389 { 1390 return buffer_get_string(&incoming_packet, length_ptr); 1391 } 1392 1393 void * 1394 packet_get_string_ptr(u_int *length_ptr) 1395 { 1396 return buffer_get_string_ptr(&incoming_packet, length_ptr); 1397 } 1398 1399 /* 1400 * Sends a diagnostic message from the server to the client. This message 1401 * can be sent at any time (but not while constructing another message). The 1402 * message is printed immediately, but only if the client is being executed 1403 * in verbose mode. These messages are primarily intended to ease debugging 1404 * authentication problems. The length of the formatted message must not 1405 * exceed 1024 bytes. This will automatically call packet_write_wait. 1406 */ 1407 1408 void 1409 packet_send_debug(const char *fmt,...) 1410 { 1411 char buf[1024]; 1412 va_list args; 1413 1414 if (compat20 && (datafellows & SSH_BUG_DEBUG)) 1415 return; 1416 1417 va_start(args, fmt); 1418 vsnprintf(buf, sizeof(buf), fmt, args); 1419 va_end(args); 1420 1421 if (compat20) { 1422 packet_start(SSH2_MSG_DEBUG); 1423 packet_put_char(0); /* bool: always display */ 1424 packet_put_cstring(buf); 1425 packet_put_cstring(""); 1426 } else { 1427 packet_start(SSH_MSG_DEBUG); 1428 packet_put_cstring(buf); 1429 } 1430 packet_send(); 1431 packet_write_wait(); 1432 } 1433 1434 /* 1435 * Logs the error plus constructs and sends a disconnect packet, closes the 1436 * connection, and exits. This function never returns. The error message 1437 * should not contain a newline. The length of the formatted message must 1438 * not exceed 1024 bytes. 1439 */ 1440 1441 void 1442 packet_disconnect(const char *fmt,...) 1443 { 1444 char buf[1024]; 1445 va_list args; 1446 static int disconnecting = 0; 1447 1448 if (disconnecting) /* Guard against recursive invocations. */ 1449 fatal("packet_disconnect called recursively."); 1450 disconnecting = 1; 1451 1452 /* 1453 * Format the message. Note that the caller must make sure the 1454 * message is of limited size. 1455 */ 1456 va_start(args, fmt); 1457 vsnprintf(buf, sizeof(buf), fmt, args); 1458 va_end(args); 1459 1460 /* Display the error locally */ 1461 logit("Disconnecting: %.100s", buf); 1462 1463 /* Send the disconnect message to the other side, and wait for it to get sent. */ 1464 if (compat20) { 1465 packet_start(SSH2_MSG_DISCONNECT); 1466 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); 1467 packet_put_cstring(buf); 1468 packet_put_cstring(""); 1469 } else { 1470 packet_start(SSH_MSG_DISCONNECT); 1471 packet_put_cstring(buf); 1472 } 1473 packet_send(); 1474 packet_write_wait(); 1475 1476 /* Stop listening for connections. */ 1477 channel_close_all(); 1478 1479 /* Close the connection. */ 1480 packet_close(); 1481 cleanup_exit(255); 1482 } 1483 1484 /* Checks if there is any buffered output, and tries to write some of the output. */ 1485 1486 void 1487 packet_write_poll(void) 1488 { 1489 int len = buffer_len(&output); 1490 1491 if (len > 0) { 1492 len = write(connection_out, buffer_ptr(&output), len); 1493 if (len == -1) { 1494 if (errno == EINTR || errno == EAGAIN || 1495 errno == EWOULDBLOCK) 1496 return; 1497 fatal("Write failed: %.100s", strerror(errno)); 1498 } 1499 if (len == 0) 1500 fatal("Write connection closed"); 1501 buffer_consume(&output, len); 1502 } 1503 } 1504 1505 1506 /* 1507 * Calls packet_write_poll repeatedly until all pending output data has been 1508 * written. 1509 */ 1510 1511 void 1512 packet_write_wait(void) 1513 { 1514 fd_set *setp; 1515 int ret, ms_remain; 1516 struct timeval start, timeout, *timeoutp = NULL; 1517 1518 setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS), 1519 sizeof(fd_mask)); 1520 packet_write_poll(); 1521 while (packet_have_data_to_write()) { 1522 memset(setp, 0, howmany(connection_out + 1, NFDBITS) * 1523 sizeof(fd_mask)); 1524 FD_SET(connection_out, setp); 1525 1526 if (packet_timeout_ms > 0) { 1527 ms_remain = packet_timeout_ms; 1528 timeoutp = &timeout; 1529 } 1530 for (;;) { 1531 if (packet_timeout_ms != -1) { 1532 ms_to_timeval(&timeout, ms_remain); 1533 gettimeofday(&start, NULL); 1534 } 1535 if ((ret = select(connection_out + 1, NULL, setp, 1536 NULL, timeoutp)) >= 0) 1537 break; 1538 if (errno != EAGAIN && errno != EINTR && 1539 errno != EWOULDBLOCK) 1540 break; 1541 if (packet_timeout_ms == -1) 1542 continue; 1543 ms_subtract_diff(&start, &ms_remain); 1544 if (ms_remain <= 0) { 1545 ret = 0; 1546 break; 1547 } 1548 } 1549 if (ret == 0) { 1550 logit("Connection to %.200s timed out while " 1551 "waiting to write", get_remote_ipaddr()); 1552 cleanup_exit(255); 1553 } 1554 packet_write_poll(); 1555 } 1556 xfree(setp); 1557 } 1558 1559 /* Returns true if there is buffered data to write to the connection. */ 1560 1561 int 1562 packet_have_data_to_write(void) 1563 { 1564 return buffer_len(&output) != 0; 1565 } 1566 1567 /* Returns true if there is not too much data to write to the connection. */ 1568 1569 int 1570 packet_not_very_much_data_to_write(void) 1571 { 1572 if (interactive_mode) 1573 return buffer_len(&output) < 16384; 1574 else 1575 return buffer_len(&output) < 128 * 1024; 1576 } 1577 1578 1579 static void 1580 packet_set_tos(int interactive) 1581 { 1582 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) 1583 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; 1584 1585 if (!packet_connection_is_on_socket() || 1586 !packet_connection_is_ipv4()) 1587 return; 1588 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, 1589 sizeof(tos)) < 0) 1590 error("setsockopt IP_TOS %d: %.100s:", 1591 tos, strerror(errno)); 1592 #endif 1593 } 1594 1595 /* Informs that the current session is interactive. Sets IP flags for that. */ 1596 1597 void 1598 packet_set_interactive(int interactive) 1599 { 1600 static int called = 0; 1601 1602 if (called) 1603 return; 1604 called = 1; 1605 1606 /* Record that we are in interactive mode. */ 1607 interactive_mode = interactive; 1608 1609 /* Only set socket options if using a socket. */ 1610 if (!packet_connection_is_on_socket()) 1611 return; 1612 set_nodelay(connection_in); 1613 packet_set_tos(interactive); 1614 } 1615 1616 /* Returns true if the current connection is interactive. */ 1617 1618 int 1619 packet_is_interactive(void) 1620 { 1621 return interactive_mode; 1622 } 1623 1624 int 1625 packet_set_maxsize(u_int s) 1626 { 1627 static int called = 0; 1628 1629 if (called) { 1630 logit("packet_set_maxsize: called twice: old %d new %d", 1631 max_packet_size, s); 1632 return -1; 1633 } 1634 if (s < 4 * 1024 || s > 1024 * 1024) { 1635 logit("packet_set_maxsize: bad size %d", s); 1636 return -1; 1637 } 1638 called = 1; 1639 debug("packet_set_maxsize: setting to %d", s); 1640 max_packet_size = s; 1641 return s; 1642 } 1643 1644 /* roundup current message to pad bytes */ 1645 void 1646 packet_add_padding(u_char pad) 1647 { 1648 extra_pad = pad; 1649 } 1650 1651 /* 1652 * 9.2. Ignored Data Message 1653 * 1654 * byte SSH_MSG_IGNORE 1655 * string data 1656 * 1657 * All implementations MUST understand (and ignore) this message at any 1658 * time (after receiving the protocol version). No implementation is 1659 * required to send them. This message can be used as an additional 1660 * protection measure against advanced traffic analysis techniques. 1661 */ 1662 void 1663 packet_send_ignore(int nbytes) 1664 { 1665 u_int32_t rnd = 0; 1666 int i; 1667 1668 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); 1669 packet_put_int(nbytes); 1670 for (i = 0; i < nbytes; i++) { 1671 if (i % 4 == 0) 1672 rnd = arc4random(); 1673 packet_put_char((u_char)rnd & 0xff); 1674 rnd >>= 8; 1675 } 1676 } 1677 1678 #define MAX_PACKETS (1U<<31) 1679 int 1680 packet_need_rekeying(void) 1681 { 1682 if (datafellows & SSH_BUG_NOREKEY) 1683 return 0; 1684 return 1685 (p_send.packets > MAX_PACKETS) || 1686 (p_read.packets > MAX_PACKETS) || 1687 (max_blocks_out && (p_send.blocks > max_blocks_out)) || 1688 (max_blocks_in && (p_read.blocks > max_blocks_in)); 1689 } 1690 1691 void 1692 packet_set_rekey_limit(u_int32_t bytes) 1693 { 1694 rekey_limit = bytes; 1695 } 1696 1697 void 1698 packet_set_server(void) 1699 { 1700 server_side = 1; 1701 } 1702 1703 void 1704 packet_set_authenticated(void) 1705 { 1706 after_authentication = 1; 1707 } 1708