1 /* $NetBSD: packet.c,v 1.2 2009/06/07 22:38:47 christos Exp $ */ 2 /* $OpenBSD: packet.c,v 1.160 2009/02/13 11:50:21 markus Exp $ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * This file contains code implementing the packet protocol and communication 8 * with the other side. This same code is used both on client and server side. 9 * 10 * As far as I am concerned, the code I have written for this software 11 * can be used freely for any purpose. Any derived versions of this 12 * software must be clearly marked as such, and if the derived work is 13 * incompatible with the protocol description in the RFC file, it must be 14 * called by a name other than "ssh" or "Secure Shell". 15 * 16 * 17 * SSH2 packet format added by Markus Friedl. 18 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 19 * 20 * Redistribution and use in source and binary forms, with or without 21 * modification, are permitted provided that the following conditions 22 * are met: 23 * 1. Redistributions of source code must retain the above copyright 24 * notice, this list of conditions and the following disclaimer. 25 * 2. Redistributions in binary form must reproduce the above copyright 26 * notice, this list of conditions and the following disclaimer in the 27 * documentation and/or other materials provided with the distribution. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 30 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 31 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 32 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 33 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 34 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 38 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 */ 40 41 #include "includes.h" 42 __RCSID("$NetBSD: packet.c,v 1.2 2009/06/07 22:38:47 christos Exp $"); 43 #include <sys/types.h> 44 #include <sys/queue.h> 45 #include <sys/socket.h> 46 #include <sys/time.h> 47 #include <sys/param.h> 48 49 #include <netinet/in_systm.h> 50 #include <netinet/in.h> 51 #include <netinet/ip.h> 52 53 #include <errno.h> 54 #include <stdarg.h> 55 #include <stdio.h> 56 #include <stdlib.h> 57 #include <string.h> 58 #include <unistd.h> 59 #include <signal.h> 60 61 #include "xmalloc.h" 62 #include "buffer.h" 63 #include "packet.h" 64 #include "crc32.h" 65 #include "compress.h" 66 #include "deattack.h" 67 #include "channels.h" 68 #include "compat.h" 69 #include "ssh1.h" 70 #include "ssh2.h" 71 #include "cipher.h" 72 #include "key.h" 73 #include "kex.h" 74 #include "mac.h" 75 #include "log.h" 76 #include "canohost.h" 77 #include "misc.h" 78 #include "ssh.h" 79 80 #ifdef PACKET_DEBUG 81 #define DBG(x) x 82 #else 83 #define DBG(x) 84 #endif 85 86 #define PACKET_MAX_SIZE (256 * 1024) 87 88 /* 89 * This variable contains the file descriptors used for communicating with 90 * the other side. connection_in is used for reading; connection_out for 91 * writing. These can be the same descriptor, in which case it is assumed to 92 * be a socket. 93 */ 94 static int connection_in = -1; 95 static int connection_out = -1; 96 97 /* Protocol flags for the remote side. */ 98 static u_int remote_protocol_flags = 0; 99 100 /* Encryption context for receiving data. This is only used for decryption. */ 101 static CipherContext receive_context; 102 103 /* Encryption context for sending data. This is only used for encryption. */ 104 static CipherContext send_context; 105 106 /* Buffer for raw input data from the socket. */ 107 Buffer input; 108 109 /* Buffer for raw output data going to the socket. */ 110 Buffer output; 111 112 /* Buffer for the partial outgoing packet being constructed. */ 113 static Buffer outgoing_packet; 114 115 /* Buffer for the incoming packet currently being processed. */ 116 static Buffer incoming_packet; 117 118 /* Scratch buffer for packet compression/decompression. */ 119 static Buffer compression_buffer; 120 static int compression_buffer_ready = 0; 121 122 /* Flag indicating whether packet compression/decompression is enabled. */ 123 static int packet_compression = 0; 124 125 /* default maximum packet size */ 126 u_int max_packet_size = 32768; 127 128 /* Flag indicating whether this module has been initialized. */ 129 static int initialized = 0; 130 131 /* Set to true if the connection is interactive. */ 132 static int interactive_mode = 0; 133 134 /* Set to true if we are the server side. */ 135 static int server_side = 0; 136 137 /* Set to true if we are authenticated. */ 138 static int after_authentication = 0; 139 140 int keep_alive_timeouts = 0; 141 142 /* Set to the maximum time that we will wait to send or receive a packet */ 143 static int packet_timeout_ms = -1; 144 145 /* Session key information for Encryption and MAC */ 146 Newkeys *newkeys[MODE_MAX]; 147 static struct packet_state { 148 u_int32_t seqnr; 149 u_int32_t packets; 150 u_int64_t blocks; 151 u_int64_t bytes; 152 } p_read, p_send; 153 154 static u_int64_t max_blocks_in, max_blocks_out; 155 static u_int32_t rekey_limit; 156 157 /* Session key for protocol v1 */ 158 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; 159 static u_int ssh1_keylen; 160 161 /* roundup current message to extra_pad bytes */ 162 static u_char extra_pad = 0; 163 164 /* XXX discard incoming data after MAC error */ 165 static u_int packet_discard = 0; 166 static Mac *packet_discard_mac = NULL; 167 168 struct packet { 169 TAILQ_ENTRY(packet) next; 170 u_char type; 171 Buffer payload; 172 }; 173 TAILQ_HEAD(, packet) outgoing; 174 175 /* 176 * Sets the descriptors used for communication. Disables encryption until 177 * packet_set_encryption_key is called. 178 */ 179 void 180 packet_set_connection(int fd_in, int fd_out) 181 { 182 Cipher *none = cipher_by_name("none"); 183 184 if (none == NULL) 185 fatal("packet_set_connection: cannot load cipher 'none'"); 186 connection_in = fd_in; 187 connection_out = fd_out; 188 cipher_init(&send_context, none, (const u_char *)"", 189 0, NULL, 0, CIPHER_ENCRYPT); 190 cipher_init(&receive_context, none, (const u_char *)"", 191 0, NULL, 0, CIPHER_DECRYPT); 192 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; 193 if (!initialized) { 194 initialized = 1; 195 buffer_init(&input); 196 buffer_init(&output); 197 buffer_init(&outgoing_packet); 198 buffer_init(&incoming_packet); 199 TAILQ_INIT(&outgoing); 200 p_send.packets = p_read.packets = 0; 201 } 202 } 203 204 void 205 packet_set_timeout(int timeout, int count) 206 { 207 if (timeout == 0 || count == 0) { 208 packet_timeout_ms = -1; 209 return; 210 } 211 if ((INT_MAX / 1000) / count < timeout) 212 packet_timeout_ms = INT_MAX; 213 else 214 packet_timeout_ms = timeout * count * 1000; 215 } 216 217 static void 218 packet_stop_discard(void) 219 { 220 if (packet_discard_mac) { 221 char buf[1024]; 222 223 memset(buf, 'a', sizeof(buf)); 224 while (buffer_len(&incoming_packet) < PACKET_MAX_SIZE) 225 buffer_append(&incoming_packet, buf, sizeof(buf)); 226 (void) mac_compute(packet_discard_mac, 227 p_read.seqnr, 228 buffer_ptr(&incoming_packet), 229 PACKET_MAX_SIZE); 230 } 231 logit("Finished discarding for %.200s", get_remote_ipaddr()); 232 cleanup_exit(255); 233 } 234 235 static void 236 packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard) 237 { 238 if (enc == NULL || !cipher_is_cbc(enc->cipher)) 239 packet_disconnect("Packet corrupt"); 240 if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled) 241 packet_discard_mac = mac; 242 if (buffer_len(&input) >= discard) 243 packet_stop_discard(); 244 packet_discard = discard - buffer_len(&input); 245 } 246 247 /* Returns 1 if remote host is connected via socket, 0 if not. */ 248 249 int 250 packet_connection_is_on_socket(void) 251 { 252 struct sockaddr_storage from, to; 253 socklen_t fromlen, tolen; 254 255 /* filedescriptors in and out are the same, so it's a socket */ 256 if (connection_in == connection_out) 257 return 1; 258 fromlen = sizeof(from); 259 memset(&from, 0, sizeof(from)); 260 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) 261 return 0; 262 tolen = sizeof(to); 263 memset(&to, 0, sizeof(to)); 264 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) 265 return 0; 266 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) 267 return 0; 268 if (from.ss_family != AF_INET && from.ss_family != AF_INET6) 269 return 0; 270 return 1; 271 } 272 273 /* 274 * Exports an IV from the CipherContext required to export the key 275 * state back from the unprivileged child to the privileged parent 276 * process. 277 */ 278 279 void 280 packet_get_keyiv(int mode, u_char *iv, u_int len) 281 { 282 CipherContext *cc; 283 284 if (mode == MODE_OUT) 285 cc = &send_context; 286 else 287 cc = &receive_context; 288 289 cipher_get_keyiv(cc, iv, len); 290 } 291 292 int 293 packet_get_keycontext(int mode, u_char *dat) 294 { 295 CipherContext *cc; 296 297 if (mode == MODE_OUT) 298 cc = &send_context; 299 else 300 cc = &receive_context; 301 302 return (cipher_get_keycontext(cc, dat)); 303 } 304 305 void 306 packet_set_keycontext(int mode, u_char *dat) 307 { 308 CipherContext *cc; 309 310 if (mode == MODE_OUT) 311 cc = &send_context; 312 else 313 cc = &receive_context; 314 315 cipher_set_keycontext(cc, dat); 316 } 317 318 int 319 packet_get_keyiv_len(int mode) 320 { 321 CipherContext *cc; 322 323 if (mode == MODE_OUT) 324 cc = &send_context; 325 else 326 cc = &receive_context; 327 328 return (cipher_get_keyiv_len(cc)); 329 } 330 331 void 332 packet_set_iv(int mode, u_char *dat) 333 { 334 CipherContext *cc; 335 336 if (mode == MODE_OUT) 337 cc = &send_context; 338 else 339 cc = &receive_context; 340 341 cipher_set_keyiv(cc, dat); 342 } 343 344 int 345 packet_get_ssh1_cipher(void) 346 { 347 return (cipher_get_number(receive_context.cipher)); 348 } 349 350 void 351 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets, 352 u_int64_t *bytes) 353 { 354 struct packet_state *state; 355 356 state = (mode == MODE_IN) ? &p_read : &p_send; 357 if (seqnr) 358 *seqnr = state->seqnr; 359 if (blocks) 360 *blocks = state->blocks; 361 if (packets) 362 *packets = state->packets; 363 if (bytes) 364 *bytes = state->bytes; 365 } 366 367 void 368 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets, 369 u_int64_t bytes) 370 { 371 struct packet_state *state; 372 373 state = (mode == MODE_IN) ? &p_read : &p_send; 374 state->seqnr = seqnr; 375 state->blocks = blocks; 376 state->packets = packets; 377 state->bytes = bytes; 378 } 379 380 /* returns 1 if connection is via ipv4 */ 381 382 int 383 packet_connection_is_ipv4(void) 384 { 385 struct sockaddr_storage to; 386 socklen_t tolen = sizeof(to); 387 388 memset(&to, 0, sizeof(to)); 389 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) 390 return 0; 391 if (to.ss_family != AF_INET) 392 return 0; 393 return 1; 394 } 395 396 /* Sets the connection into non-blocking mode. */ 397 398 void 399 packet_set_nonblocking(void) 400 { 401 /* Set the socket into non-blocking mode. */ 402 set_nonblock(connection_in); 403 404 if (connection_out != connection_in) 405 set_nonblock(connection_out); 406 } 407 408 /* Returns the socket used for reading. */ 409 410 int 411 packet_get_connection_in(void) 412 { 413 return connection_in; 414 } 415 416 /* Returns the descriptor used for writing. */ 417 418 int 419 packet_get_connection_out(void) 420 { 421 return connection_out; 422 } 423 424 /* Closes the connection and clears and frees internal data structures. */ 425 426 void 427 packet_close(void) 428 { 429 if (!initialized) 430 return; 431 initialized = 0; 432 if (connection_in == connection_out) { 433 shutdown(connection_out, SHUT_RDWR); 434 close(connection_out); 435 } else { 436 close(connection_in); 437 close(connection_out); 438 } 439 buffer_free(&input); 440 buffer_free(&output); 441 buffer_free(&outgoing_packet); 442 buffer_free(&incoming_packet); 443 if (compression_buffer_ready) { 444 buffer_free(&compression_buffer); 445 buffer_compress_uninit(); 446 } 447 cipher_cleanup(&send_context); 448 cipher_cleanup(&receive_context); 449 } 450 451 /* Sets remote side protocol flags. */ 452 453 void 454 packet_set_protocol_flags(u_int protocol_flags) 455 { 456 remote_protocol_flags = protocol_flags; 457 } 458 459 /* Returns the remote protocol flags set earlier by the above function. */ 460 461 u_int 462 packet_get_protocol_flags(void) 463 { 464 return remote_protocol_flags; 465 } 466 467 /* 468 * Starts packet compression from the next packet on in both directions. 469 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. 470 */ 471 472 static void 473 packet_init_compression(void) 474 { 475 if (compression_buffer_ready == 1) 476 return; 477 compression_buffer_ready = 1; 478 buffer_init(&compression_buffer); 479 } 480 481 void 482 packet_start_compression(int level) 483 { 484 if (packet_compression && !compat20) 485 fatal("Compression already enabled."); 486 packet_compression = 1; 487 packet_init_compression(); 488 buffer_compress_init_send(level); 489 buffer_compress_init_recv(); 490 } 491 492 /* 493 * Causes any further packets to be encrypted using the given key. The same 494 * key is used for both sending and reception. However, both directions are 495 * encrypted independently of each other. 496 */ 497 498 void 499 packet_set_encryption_key(const u_char *key, u_int keylen, 500 int number) 501 { 502 Cipher *cipher = cipher_by_number(number); 503 504 if (cipher == NULL) 505 fatal("packet_set_encryption_key: unknown cipher number %d", number); 506 if (keylen < 20) 507 fatal("packet_set_encryption_key: keylen too small: %d", keylen); 508 if (keylen > SSH_SESSION_KEY_LENGTH) 509 fatal("packet_set_encryption_key: keylen too big: %d", keylen); 510 memcpy(ssh1_key, key, keylen); 511 ssh1_keylen = keylen; 512 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); 513 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); 514 } 515 516 u_int 517 packet_get_encryption_key(u_char *key) 518 { 519 if (key == NULL) 520 return (ssh1_keylen); 521 memcpy(key, ssh1_key, ssh1_keylen); 522 return (ssh1_keylen); 523 } 524 525 /* Start constructing a packet to send. */ 526 void 527 packet_start(u_char type) 528 { 529 u_char buf[9]; 530 int len; 531 532 DBG(debug("packet_start[%d]", type)); 533 len = compat20 ? 6 : 9; 534 memset(buf, 0, len - 1); 535 buf[len - 1] = type; 536 buffer_clear(&outgoing_packet); 537 buffer_append(&outgoing_packet, buf, len); 538 } 539 540 /* Append payload. */ 541 void 542 packet_put_char(int value) 543 { 544 char ch = value; 545 546 buffer_append(&outgoing_packet, &ch, 1); 547 } 548 549 void 550 packet_put_int(u_int value) 551 { 552 buffer_put_int(&outgoing_packet, value); 553 } 554 555 void 556 packet_put_string(const void *buf, u_int len) 557 { 558 buffer_put_string(&outgoing_packet, buf, len); 559 } 560 561 void 562 packet_put_cstring(const char *str) 563 { 564 buffer_put_cstring(&outgoing_packet, str); 565 } 566 567 void 568 packet_put_raw(const void *buf, u_int len) 569 { 570 buffer_append(&outgoing_packet, buf, len); 571 } 572 573 void 574 packet_put_bignum(BIGNUM * value) 575 { 576 buffer_put_bignum(&outgoing_packet, value); 577 } 578 579 void 580 packet_put_bignum2(BIGNUM * value) 581 { 582 buffer_put_bignum2(&outgoing_packet, value); 583 } 584 585 /* 586 * Finalizes and sends the packet. If the encryption key has been set, 587 * encrypts the packet before sending. 588 */ 589 590 static void 591 packet_send1(void) 592 { 593 u_char buf[8], *cp; 594 int i, padding, len; 595 u_int checksum; 596 u_int32_t rnd = 0; 597 598 /* 599 * If using packet compression, compress the payload of the outgoing 600 * packet. 601 */ 602 if (packet_compression) { 603 buffer_clear(&compression_buffer); 604 /* Skip padding. */ 605 buffer_consume(&outgoing_packet, 8); 606 /* padding */ 607 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); 608 buffer_compress(&outgoing_packet, &compression_buffer); 609 buffer_clear(&outgoing_packet); 610 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 611 buffer_len(&compression_buffer)); 612 } 613 /* Compute packet length without padding (add checksum, remove padding). */ 614 len = buffer_len(&outgoing_packet) + 4 - 8; 615 616 /* Insert padding. Initialized to zero in packet_start1() */ 617 padding = 8 - len % 8; 618 if (!send_context.plaintext) { 619 cp = buffer_ptr(&outgoing_packet); 620 for (i = 0; i < padding; i++) { 621 if (i % 4 == 0) 622 rnd = arc4random(); 623 cp[7 - i] = rnd & 0xff; 624 rnd >>= 8; 625 } 626 } 627 buffer_consume(&outgoing_packet, 8 - padding); 628 629 /* Add check bytes. */ 630 checksum = ssh_crc32(buffer_ptr(&outgoing_packet), 631 buffer_len(&outgoing_packet)); 632 put_u32(buf, checksum); 633 buffer_append(&outgoing_packet, buf, 4); 634 635 #ifdef PACKET_DEBUG 636 fprintf(stderr, "packet_send plain: "); 637 buffer_dump(&outgoing_packet); 638 #endif 639 640 /* Append to output. */ 641 put_u32(buf, len); 642 buffer_append(&output, buf, 4); 643 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 644 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 645 buffer_len(&outgoing_packet)); 646 647 #ifdef PACKET_DEBUG 648 fprintf(stderr, "encrypted: "); 649 buffer_dump(&output); 650 #endif 651 p_send.packets++; 652 p_send.bytes += len + buffer_len(&outgoing_packet); 653 buffer_clear(&outgoing_packet); 654 655 /* 656 * Note that the packet is now only buffered in output. It won't be 657 * actually sent until packet_write_wait or packet_write_poll is 658 * called. 659 */ 660 } 661 662 void 663 set_newkeys(int mode) 664 { 665 Enc *enc; 666 Mac *mac; 667 Comp *comp; 668 CipherContext *cc; 669 u_int64_t *max_blocks; 670 int crypt_type; 671 672 debug2("set_newkeys: mode %d", mode); 673 674 if (mode == MODE_OUT) { 675 cc = &send_context; 676 crypt_type = CIPHER_ENCRYPT; 677 p_send.packets = p_send.blocks = 0; 678 max_blocks = &max_blocks_out; 679 } else { 680 cc = &receive_context; 681 crypt_type = CIPHER_DECRYPT; 682 p_read.packets = p_read.blocks = 0; 683 max_blocks = &max_blocks_in; 684 } 685 if (newkeys[mode] != NULL) { 686 debug("set_newkeys: rekeying"); 687 cipher_cleanup(cc); 688 enc = &newkeys[mode]->enc; 689 mac = &newkeys[mode]->mac; 690 comp = &newkeys[mode]->comp; 691 mac_clear(mac); 692 xfree(enc->name); 693 xfree(enc->iv); 694 xfree(enc->key); 695 xfree(mac->name); 696 xfree(mac->key); 697 xfree(comp->name); 698 xfree(newkeys[mode]); 699 } 700 newkeys[mode] = kex_get_newkeys(mode); 701 if (newkeys[mode] == NULL) 702 fatal("newkeys: no keys for mode %d", mode); 703 enc = &newkeys[mode]->enc; 704 mac = &newkeys[mode]->mac; 705 comp = &newkeys[mode]->comp; 706 if (mac_init(mac) == 0) 707 mac->enabled = 1; 708 DBG(debug("cipher_init_context: %d", mode)); 709 cipher_init(cc, enc->cipher, enc->key, enc->key_len, 710 enc->iv, enc->block_size, crypt_type); 711 /* Deleting the keys does not gain extra security */ 712 /* memset(enc->iv, 0, enc->block_size); 713 memset(enc->key, 0, enc->key_len); 714 memset(mac->key, 0, mac->key_len); */ 715 if ((comp->type == COMP_ZLIB || 716 (comp->type == COMP_DELAYED && after_authentication)) && 717 comp->enabled == 0) { 718 packet_init_compression(); 719 if (mode == MODE_OUT) 720 buffer_compress_init_send(6); 721 else 722 buffer_compress_init_recv(); 723 comp->enabled = 1; 724 } 725 /* 726 * The 2^(blocksize*2) limit is too expensive for 3DES, 727 * blowfish, etc, so enforce a 1GB limit for small blocksizes. 728 */ 729 if (enc->block_size >= 16) 730 *max_blocks = (u_int64_t)1 << (enc->block_size*2); 731 else 732 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; 733 if (rekey_limit) 734 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); 735 } 736 737 /* 738 * Delayed compression for SSH2 is enabled after authentication: 739 * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent, 740 * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received. 741 */ 742 static void 743 packet_enable_delayed_compress(void) 744 { 745 Comp *comp = NULL; 746 int mode; 747 748 /* 749 * Remember that we are past the authentication step, so rekeying 750 * with COMP_DELAYED will turn on compression immediately. 751 */ 752 after_authentication = 1; 753 for (mode = 0; mode < MODE_MAX; mode++) { 754 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */ 755 if (newkeys[mode] == NULL) 756 continue; 757 comp = &newkeys[mode]->comp; 758 if (comp && !comp->enabled && comp->type == COMP_DELAYED) { 759 packet_init_compression(); 760 if (mode == MODE_OUT) 761 buffer_compress_init_send(6); 762 else 763 buffer_compress_init_recv(); 764 comp->enabled = 1; 765 } 766 } 767 } 768 769 /* 770 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) 771 */ 772 static int 773 packet_send2_wrapped(void) 774 { 775 u_char type, *cp, *macbuf = NULL; 776 u_char padlen, pad; 777 u_int packet_length = 0; 778 u_int i, len; 779 u_int32_t rnd = 0; 780 Enc *enc = NULL; 781 Mac *mac = NULL; 782 Comp *comp = NULL; 783 int block_size; 784 785 if (newkeys[MODE_OUT] != NULL) { 786 enc = &newkeys[MODE_OUT]->enc; 787 mac = &newkeys[MODE_OUT]->mac; 788 comp = &newkeys[MODE_OUT]->comp; 789 } 790 block_size = enc ? enc->block_size : 8; 791 792 cp = buffer_ptr(&outgoing_packet); 793 type = cp[5]; 794 795 #ifdef PACKET_DEBUG 796 fprintf(stderr, "plain: "); 797 buffer_dump(&outgoing_packet); 798 #endif 799 800 if (comp && comp->enabled) { 801 len = buffer_len(&outgoing_packet); 802 /* skip header, compress only payload */ 803 buffer_consume(&outgoing_packet, 5); 804 buffer_clear(&compression_buffer); 805 buffer_compress(&outgoing_packet, &compression_buffer); 806 buffer_clear(&outgoing_packet); 807 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); 808 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 809 buffer_len(&compression_buffer)); 810 DBG(debug("compression: raw %d compressed %d", len, 811 buffer_len(&outgoing_packet))); 812 } 813 814 /* sizeof (packet_len + pad_len + payload) */ 815 len = buffer_len(&outgoing_packet); 816 817 /* 818 * calc size of padding, alloc space, get random data, 819 * minimum padding is 4 bytes 820 */ 821 padlen = block_size - (len % block_size); 822 if (padlen < 4) 823 padlen += block_size; 824 if (extra_pad) { 825 /* will wrap if extra_pad+padlen > 255 */ 826 extra_pad = roundup(extra_pad, block_size); 827 pad = extra_pad - ((len + padlen) % extra_pad); 828 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", 829 pad, len, padlen, extra_pad); 830 padlen += pad; 831 extra_pad = 0; 832 } 833 cp = buffer_append_space(&outgoing_packet, padlen); 834 if (enc && !send_context.plaintext) { 835 /* random padding */ 836 for (i = 0; i < padlen; i++) { 837 if (i % 4 == 0) 838 rnd = arc4random(); 839 cp[i] = rnd & 0xff; 840 rnd >>= 8; 841 } 842 } else { 843 /* clear padding */ 844 memset(cp, 0, padlen); 845 } 846 /* packet_length includes payload, padding and padding length field */ 847 packet_length = buffer_len(&outgoing_packet) - 4; 848 cp = buffer_ptr(&outgoing_packet); 849 put_u32(cp, packet_length); 850 cp[4] = padlen; 851 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); 852 853 /* compute MAC over seqnr and packet(length fields, payload, padding) */ 854 if (mac && mac->enabled) { 855 macbuf = mac_compute(mac, p_send.seqnr, 856 buffer_ptr(&outgoing_packet), 857 buffer_len(&outgoing_packet)); 858 DBG(debug("done calc MAC out #%d", p_send.seqnr)); 859 } 860 /* encrypt packet and append to output buffer. */ 861 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 862 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 863 buffer_len(&outgoing_packet)); 864 /* append unencrypted MAC */ 865 if (mac && mac->enabled) 866 buffer_append(&output, macbuf, mac->mac_len); 867 #ifdef PACKET_DEBUG 868 fprintf(stderr, "encrypted: "); 869 buffer_dump(&output); 870 #endif 871 /* increment sequence number for outgoing packets */ 872 if (++p_send.seqnr == 0) 873 logit("outgoing seqnr wraps around"); 874 if (++p_send.packets == 0) 875 if (!(datafellows & SSH_BUG_NOREKEY)) 876 fatal("XXX too many packets with same key"); 877 p_send.blocks += (packet_length + 4) / block_size; 878 p_send.bytes += packet_length + 4; 879 buffer_clear(&outgoing_packet); 880 881 if (type == SSH2_MSG_NEWKEYS) 882 set_newkeys(MODE_OUT); 883 else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side) 884 packet_enable_delayed_compress(); 885 return(packet_length); 886 } 887 888 static int 889 packet_send2(void) 890 { 891 static int packet_length = 0; 892 static int rekeying = 0; 893 struct packet *p; 894 u_char type, *cp; 895 896 cp = buffer_ptr(&outgoing_packet); 897 type = cp[5]; 898 899 /* during rekeying we can only send key exchange messages */ 900 if (rekeying) { 901 if (!((type >= SSH2_MSG_TRANSPORT_MIN) && 902 (type <= SSH2_MSG_TRANSPORT_MAX))) { 903 debug("enqueue packet: %u", type); 904 p = xmalloc(sizeof(*p)); 905 p->type = type; 906 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); 907 buffer_init(&outgoing_packet); 908 TAILQ_INSERT_TAIL(&outgoing, p, next); 909 return(sizeof(Buffer)); 910 } 911 } 912 913 /* rekeying starts with sending KEXINIT */ 914 if (type == SSH2_MSG_KEXINIT) 915 rekeying = 1; 916 917 packet_length = packet_send2_wrapped(); 918 919 /* after a NEWKEYS message we can send the complete queue */ 920 if (type == SSH2_MSG_NEWKEYS) { 921 rekeying = 0; 922 while ((p = TAILQ_FIRST(&outgoing))) { 923 type = p->type; 924 debug("dequeue packet: %u", type); 925 buffer_free(&outgoing_packet); 926 memcpy(&outgoing_packet, &p->payload, 927 sizeof(Buffer)); 928 TAILQ_REMOVE(&outgoing, p, next); 929 xfree(p); 930 packet_length += packet_send2_wrapped(); 931 } 932 } 933 return(packet_length); 934 } 935 936 int 937 packet_send(void) 938 { 939 int packet_len = 0; 940 if (compat20) 941 packet_len = packet_send2(); 942 else 943 packet_send1(); 944 DBG(debug("packet_send done")); 945 return packet_len; 946 } 947 948 /* 949 * Waits until a packet has been received, and returns its type. Note that 950 * no other data is processed until this returns, so this function should not 951 * be used during the interactive session. 952 */ 953 954 int 955 packet_read_seqnr(u_int32_t *seqnr_p) 956 { 957 int type, len, ret, ms_remain; 958 fd_set *setp; 959 char buf[8192]; 960 struct timeval timeout, start, *timeoutp = NULL; 961 962 DBG(debug("packet_read()")); 963 964 setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS), 965 sizeof(fd_mask)); 966 967 /* Since we are blocking, ensure that all written packets have been sent. */ 968 packet_write_wait(); 969 970 /* Stay in the loop until we have received a complete packet. */ 971 for (;;) { 972 /* Try to read a packet from the buffer. */ 973 type = packet_read_poll_seqnr(seqnr_p); 974 if (!compat20 && ( 975 type == SSH_SMSG_SUCCESS 976 || type == SSH_SMSG_FAILURE 977 || type == SSH_CMSG_EOF 978 || type == SSH_CMSG_EXIT_CONFIRMATION)) 979 packet_check_eom(); 980 /* If we got a packet, return it. */ 981 if (type != SSH_MSG_NONE) { 982 xfree(setp); 983 return type; 984 } 985 /* 986 * Otherwise, wait for some data to arrive, add it to the 987 * buffer, and try again. 988 */ 989 memset(setp, 0, howmany(connection_in + 1, NFDBITS) * 990 sizeof(fd_mask)); 991 FD_SET(connection_in, setp); 992 993 if (packet_timeout_ms > 0) { 994 ms_remain = packet_timeout_ms; 995 timeoutp = &timeout; 996 } 997 /* Wait for some data to arrive. */ 998 for (;;) { 999 if (packet_timeout_ms != -1) { 1000 ms_to_timeval(&timeout, ms_remain); 1001 gettimeofday(&start, NULL); 1002 } 1003 if ((ret = select(connection_in + 1, setp, NULL, 1004 NULL, timeoutp)) >= 0) 1005 break; 1006 if (errno != EAGAIN && errno != EINTR) 1007 break; 1008 if (packet_timeout_ms == -1) 1009 continue; 1010 ms_subtract_diff(&start, &ms_remain); 1011 if (ms_remain <= 0) { 1012 ret = 0; 1013 break; 1014 } 1015 } 1016 if (ret == 0) { 1017 logit("Connection to %.200s timed out while " 1018 "waiting to read", get_remote_ipaddr()); 1019 cleanup_exit(255); 1020 } 1021 /* Read data from the socket. */ 1022 len = read(connection_in, buf, sizeof(buf)); 1023 if (len == 0) { 1024 logit("Connection closed by %.200s", get_remote_ipaddr()); 1025 cleanup_exit(255); 1026 } 1027 if (len < 0) 1028 fatal("Read from socket failed: %.100s", strerror(errno)); 1029 /* Append it to the buffer. */ 1030 packet_process_incoming(buf, len); 1031 } 1032 /* NOTREACHED */ 1033 } 1034 1035 int 1036 packet_read(void) 1037 { 1038 return packet_read_seqnr(NULL); 1039 } 1040 1041 /* 1042 * Waits until a packet has been received, verifies that its type matches 1043 * that given, and gives a fatal error and exits if there is a mismatch. 1044 */ 1045 1046 void 1047 packet_read_expect(int expected_type) 1048 { 1049 int type; 1050 1051 type = packet_read(); 1052 if (type != expected_type) 1053 packet_disconnect("Protocol error: expected packet type %d, got %d", 1054 expected_type, type); 1055 } 1056 1057 /* Checks if a full packet is available in the data received so far via 1058 * packet_process_incoming. If so, reads the packet; otherwise returns 1059 * SSH_MSG_NONE. This does not wait for data from the connection. 1060 * 1061 * SSH_MSG_DISCONNECT is handled specially here. Also, 1062 * SSH_MSG_IGNORE messages are skipped by this function and are never returned 1063 * to higher levels. 1064 */ 1065 1066 static int 1067 packet_read_poll1(void) 1068 { 1069 u_int len, padded_len; 1070 u_char *cp, type; 1071 u_int checksum, stored_checksum; 1072 1073 /* Check if input size is less than minimum packet size. */ 1074 if (buffer_len(&input) < 4 + 8) 1075 return SSH_MSG_NONE; 1076 /* Get length of incoming packet. */ 1077 cp = buffer_ptr(&input); 1078 len = get_u32(cp); 1079 if (len < 1 + 2 + 2 || len > 256 * 1024) 1080 packet_disconnect("Bad packet length %u.", len); 1081 padded_len = (len + 8) & ~7; 1082 1083 /* Check if the packet has been entirely received. */ 1084 if (buffer_len(&input) < 4 + padded_len) 1085 return SSH_MSG_NONE; 1086 1087 /* The entire packet is in buffer. */ 1088 1089 /* Consume packet length. */ 1090 buffer_consume(&input, 4); 1091 1092 /* 1093 * Cryptographic attack detector for ssh 1094 * (C)1998 CORE-SDI, Buenos Aires Argentina 1095 * Ariel Futoransky(futo@core-sdi.com) 1096 */ 1097 if (!receive_context.plaintext) { 1098 switch (detect_attack(buffer_ptr(&input), padded_len)) { 1099 case DEATTACK_DETECTED: 1100 packet_disconnect("crc32 compensation attack: " 1101 "network attack detected"); 1102 case DEATTACK_DOS_DETECTED: 1103 packet_disconnect("deattack denial of " 1104 "service detected"); 1105 } 1106 } 1107 1108 /* Decrypt data to incoming_packet. */ 1109 buffer_clear(&incoming_packet); 1110 cp = buffer_append_space(&incoming_packet, padded_len); 1111 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); 1112 1113 buffer_consume(&input, padded_len); 1114 1115 #ifdef PACKET_DEBUG 1116 fprintf(stderr, "read_poll plain: "); 1117 buffer_dump(&incoming_packet); 1118 #endif 1119 1120 /* Compute packet checksum. */ 1121 checksum = ssh_crc32(buffer_ptr(&incoming_packet), 1122 buffer_len(&incoming_packet) - 4); 1123 1124 /* Skip padding. */ 1125 buffer_consume(&incoming_packet, 8 - len % 8); 1126 1127 /* Test check bytes. */ 1128 if (len != buffer_len(&incoming_packet)) 1129 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", 1130 len, buffer_len(&incoming_packet)); 1131 1132 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; 1133 stored_checksum = get_u32(cp); 1134 if (checksum != stored_checksum) 1135 packet_disconnect("Corrupted check bytes on input."); 1136 buffer_consume_end(&incoming_packet, 4); 1137 1138 if (packet_compression) { 1139 buffer_clear(&compression_buffer); 1140 buffer_uncompress(&incoming_packet, &compression_buffer); 1141 buffer_clear(&incoming_packet); 1142 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1143 buffer_len(&compression_buffer)); 1144 } 1145 p_read.packets++; 1146 p_read.bytes += padded_len + 4; 1147 type = buffer_get_char(&incoming_packet); 1148 if (type < SSH_MSG_MIN || type > SSH_MSG_MAX) 1149 packet_disconnect("Invalid ssh1 packet type: %d", type); 1150 return type; 1151 } 1152 1153 static int 1154 packet_read_poll2(u_int32_t *seqnr_p) 1155 { 1156 static u_int packet_length = 0; 1157 u_int padlen, need; 1158 u_char *macbuf, *cp, type; 1159 u_int maclen, block_size; 1160 Enc *enc = NULL; 1161 Mac *mac = NULL; 1162 Comp *comp = NULL; 1163 1164 if (packet_discard) 1165 return SSH_MSG_NONE; 1166 1167 if (newkeys[MODE_IN] != NULL) { 1168 enc = &newkeys[MODE_IN]->enc; 1169 mac = &newkeys[MODE_IN]->mac; 1170 comp = &newkeys[MODE_IN]->comp; 1171 } 1172 maclen = mac && mac->enabled ? mac->mac_len : 0; 1173 block_size = enc ? enc->block_size : 8; 1174 1175 if (packet_length == 0) { 1176 /* 1177 * check if input size is less than the cipher block size, 1178 * decrypt first block and extract length of incoming packet 1179 */ 1180 if (buffer_len(&input) < block_size) 1181 return SSH_MSG_NONE; 1182 buffer_clear(&incoming_packet); 1183 cp = buffer_append_space(&incoming_packet, block_size); 1184 cipher_crypt(&receive_context, cp, buffer_ptr(&input), 1185 block_size); 1186 cp = buffer_ptr(&incoming_packet); 1187 packet_length = get_u32(cp); 1188 if (packet_length < 1 + 4 || packet_length > PACKET_MAX_SIZE) { 1189 #ifdef PACKET_DEBUG 1190 buffer_dump(&incoming_packet); 1191 #endif 1192 logit("Bad packet length %u.", packet_length); 1193 packet_start_discard(enc, mac, packet_length, 1194 PACKET_MAX_SIZE); 1195 return SSH_MSG_NONE; 1196 } 1197 DBG(debug("input: packet len %u", packet_length+4)); 1198 buffer_consume(&input, block_size); 1199 } 1200 /* we have a partial packet of block_size bytes */ 1201 need = 4 + packet_length - block_size; 1202 DBG(debug("partial packet %d, need %d, maclen %d", block_size, 1203 need, maclen)); 1204 if (need % block_size != 0) { 1205 logit("padding error: need %d block %d mod %d", 1206 need, block_size, need % block_size); 1207 packet_start_discard(enc, mac, packet_length, 1208 PACKET_MAX_SIZE - block_size); 1209 return SSH_MSG_NONE; 1210 } 1211 /* 1212 * check if the entire packet has been received and 1213 * decrypt into incoming_packet 1214 */ 1215 if (buffer_len(&input) < need + maclen) 1216 return SSH_MSG_NONE; 1217 #ifdef PACKET_DEBUG 1218 fprintf(stderr, "read_poll enc/full: "); 1219 buffer_dump(&input); 1220 #endif 1221 cp = buffer_append_space(&incoming_packet, need); 1222 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); 1223 buffer_consume(&input, need); 1224 /* 1225 * compute MAC over seqnr and packet, 1226 * increment sequence number for incoming packet 1227 */ 1228 if (mac && mac->enabled) { 1229 macbuf = mac_compute(mac, p_read.seqnr, 1230 buffer_ptr(&incoming_packet), 1231 buffer_len(&incoming_packet)); 1232 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) { 1233 logit("Corrupted MAC on input."); 1234 if (need > PACKET_MAX_SIZE) 1235 fatal("internal error need %d", need); 1236 packet_start_discard(enc, mac, packet_length, 1237 PACKET_MAX_SIZE - need); 1238 return SSH_MSG_NONE; 1239 } 1240 1241 DBG(debug("MAC #%d ok", p_read.seqnr)); 1242 buffer_consume(&input, mac->mac_len); 1243 } 1244 /* XXX now it's safe to use fatal/packet_disconnect */ 1245 if (seqnr_p != NULL) 1246 *seqnr_p = p_read.seqnr; 1247 if (++p_read.seqnr == 0) 1248 logit("incoming seqnr wraps around"); 1249 if (++p_read.packets == 0) 1250 if (!(datafellows & SSH_BUG_NOREKEY)) 1251 fatal("XXX too many packets with same key"); 1252 p_read.blocks += (packet_length + 4) / block_size; 1253 p_read.bytes += packet_length + 4; 1254 1255 /* get padlen */ 1256 cp = buffer_ptr(&incoming_packet); 1257 padlen = cp[4]; 1258 DBG(debug("input: padlen %d", padlen)); 1259 if (padlen < 4) 1260 packet_disconnect("Corrupted padlen %d on input.", padlen); 1261 1262 /* skip packet size + padlen, discard padding */ 1263 buffer_consume(&incoming_packet, 4 + 1); 1264 buffer_consume_end(&incoming_packet, padlen); 1265 1266 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); 1267 if (comp && comp->enabled) { 1268 buffer_clear(&compression_buffer); 1269 buffer_uncompress(&incoming_packet, &compression_buffer); 1270 buffer_clear(&incoming_packet); 1271 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1272 buffer_len(&compression_buffer)); 1273 DBG(debug("input: len after de-compress %d", 1274 buffer_len(&incoming_packet))); 1275 } 1276 /* 1277 * get packet type, implies consume. 1278 * return length of payload (without type field) 1279 */ 1280 type = buffer_get_char(&incoming_packet); 1281 if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN) 1282 packet_disconnect("Invalid ssh2 packet type: %d", type); 1283 if (type == SSH2_MSG_NEWKEYS) 1284 set_newkeys(MODE_IN); 1285 else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side) 1286 packet_enable_delayed_compress(); 1287 #ifdef PACKET_DEBUG 1288 fprintf(stderr, "read/plain[%d]:\r\n", type); 1289 buffer_dump(&incoming_packet); 1290 #endif 1291 /* reset for next packet */ 1292 packet_length = 0; 1293 return type; 1294 } 1295 1296 int 1297 packet_read_poll_seqnr(u_int32_t *seqnr_p) 1298 { 1299 u_int reason, seqnr; 1300 u_char type; 1301 char *msg; 1302 1303 for (;;) { 1304 if (compat20) { 1305 type = packet_read_poll2(seqnr_p); 1306 if (type) { 1307 keep_alive_timeouts = 0; 1308 DBG(debug("received packet type %d", type)); 1309 } 1310 switch (type) { 1311 case SSH2_MSG_IGNORE: 1312 debug3("Received SSH2_MSG_IGNORE"); 1313 break; 1314 case SSH2_MSG_DEBUG: 1315 packet_get_char(); 1316 msg = packet_get_string(NULL); 1317 debug("Remote: %.900s", msg); 1318 xfree(msg); 1319 msg = packet_get_string(NULL); 1320 xfree(msg); 1321 break; 1322 case SSH2_MSG_DISCONNECT: 1323 reason = packet_get_int(); 1324 msg = packet_get_string(NULL); 1325 logit("Received disconnect from %s: %u: %.400s", 1326 get_remote_ipaddr(), reason, msg); 1327 xfree(msg); 1328 cleanup_exit(255); 1329 break; 1330 case SSH2_MSG_UNIMPLEMENTED: 1331 seqnr = packet_get_int(); 1332 debug("Received SSH2_MSG_UNIMPLEMENTED for %u", 1333 seqnr); 1334 break; 1335 default: 1336 return type; 1337 } 1338 } else { 1339 type = packet_read_poll1(); 1340 switch (type) { 1341 case SSH_MSG_IGNORE: 1342 break; 1343 case SSH_MSG_DEBUG: 1344 msg = packet_get_string(NULL); 1345 debug("Remote: %.900s", msg); 1346 xfree(msg); 1347 break; 1348 case SSH_MSG_DISCONNECT: 1349 msg = packet_get_string(NULL); 1350 logit("Received disconnect from %s: %.400s", 1351 get_remote_ipaddr(), msg); 1352 cleanup_exit(255); 1353 break; 1354 default: 1355 if (type) 1356 DBG(debug("received packet type %d", type)); 1357 return type; 1358 } 1359 } 1360 } 1361 } 1362 1363 int 1364 packet_read_poll(void) 1365 { 1366 return packet_read_poll_seqnr(NULL); 1367 } 1368 1369 /* 1370 * Buffers the given amount of input characters. This is intended to be used 1371 * together with packet_read_poll. 1372 */ 1373 1374 void 1375 packet_process_incoming(const char *buf, u_int len) 1376 { 1377 if (packet_discard) { 1378 keep_alive_timeouts = 0; /* ?? */ 1379 if (len >= packet_discard) 1380 packet_stop_discard(); 1381 packet_discard -= len; 1382 return; 1383 } 1384 buffer_append(&input, buf, len); 1385 } 1386 1387 /* Returns a character from the packet. */ 1388 1389 u_int 1390 packet_get_char(void) 1391 { 1392 char ch; 1393 1394 buffer_get(&incoming_packet, &ch, 1); 1395 return (u_char) ch; 1396 } 1397 1398 /* Returns an integer from the packet data. */ 1399 1400 u_int 1401 packet_get_int(void) 1402 { 1403 return buffer_get_int(&incoming_packet); 1404 } 1405 1406 /* 1407 * Returns an arbitrary precision integer from the packet data. The integer 1408 * must have been initialized before this call. 1409 */ 1410 1411 void 1412 packet_get_bignum(BIGNUM * value) 1413 { 1414 buffer_get_bignum(&incoming_packet, value); 1415 } 1416 1417 void 1418 packet_get_bignum2(BIGNUM * value) 1419 { 1420 buffer_get_bignum2(&incoming_packet, value); 1421 } 1422 1423 void * 1424 packet_get_raw(u_int *length_ptr) 1425 { 1426 u_int bytes = buffer_len(&incoming_packet); 1427 1428 if (length_ptr != NULL) 1429 *length_ptr = bytes; 1430 return buffer_ptr(&incoming_packet); 1431 } 1432 1433 int 1434 packet_remaining(void) 1435 { 1436 return buffer_len(&incoming_packet); 1437 } 1438 1439 /* 1440 * Returns a string from the packet data. The string is allocated using 1441 * xmalloc; it is the responsibility of the calling program to free it when 1442 * no longer needed. The length_ptr argument may be NULL, or point to an 1443 * integer into which the length of the string is stored. 1444 */ 1445 1446 void * 1447 packet_get_string(u_int *length_ptr) 1448 { 1449 return buffer_get_string(&incoming_packet, length_ptr); 1450 } 1451 1452 void * 1453 packet_get_string_ptr(u_int *length_ptr) 1454 { 1455 return buffer_get_string_ptr(&incoming_packet, length_ptr); 1456 } 1457 1458 /* 1459 * Sends a diagnostic message from the server to the client. This message 1460 * can be sent at any time (but not while constructing another message). The 1461 * message is printed immediately, but only if the client is being executed 1462 * in verbose mode. These messages are primarily intended to ease debugging 1463 * authentication problems. The length of the formatted message must not 1464 * exceed 1024 bytes. This will automatically call packet_write_wait. 1465 */ 1466 1467 void 1468 packet_send_debug(const char *fmt,...) 1469 { 1470 char buf[1024]; 1471 va_list args; 1472 1473 if (compat20 && (datafellows & SSH_BUG_DEBUG)) 1474 return; 1475 1476 va_start(args, fmt); 1477 vsnprintf(buf, sizeof(buf), fmt, args); 1478 va_end(args); 1479 1480 if (compat20) { 1481 packet_start(SSH2_MSG_DEBUG); 1482 packet_put_char(0); /* bool: always display */ 1483 packet_put_cstring(buf); 1484 packet_put_cstring(""); 1485 } else { 1486 packet_start(SSH_MSG_DEBUG); 1487 packet_put_cstring(buf); 1488 } 1489 packet_send(); 1490 packet_write_wait(); 1491 } 1492 1493 /* 1494 * Logs the error plus constructs and sends a disconnect packet, closes the 1495 * connection, and exits. This function never returns. The error message 1496 * should not contain a newline. The length of the formatted message must 1497 * not exceed 1024 bytes. 1498 */ 1499 1500 void 1501 packet_disconnect(const char *fmt,...) 1502 { 1503 char buf[1024]; 1504 va_list args; 1505 static int disconnecting = 0; 1506 1507 if (disconnecting) /* Guard against recursive invocations. */ 1508 fatal("packet_disconnect called recursively."); 1509 disconnecting = 1; 1510 1511 /* 1512 * Format the message. Note that the caller must make sure the 1513 * message is of limited size. 1514 */ 1515 va_start(args, fmt); 1516 vsnprintf(buf, sizeof(buf), fmt, args); 1517 va_end(args); 1518 1519 /* Display the error locally */ 1520 logit("Disconnecting: %.100s", buf); 1521 1522 /* Send the disconnect message to the other side, and wait for it to get sent. */ 1523 if (compat20) { 1524 packet_start(SSH2_MSG_DISCONNECT); 1525 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); 1526 packet_put_cstring(buf); 1527 packet_put_cstring(""); 1528 } else { 1529 packet_start(SSH_MSG_DISCONNECT); 1530 packet_put_cstring(buf); 1531 } 1532 packet_send(); 1533 packet_write_wait(); 1534 1535 /* Stop listening for connections. */ 1536 channel_close_all(); 1537 1538 /* Close the connection. */ 1539 packet_close(); 1540 cleanup_exit(255); 1541 } 1542 1543 /* Checks if there is any buffered output, and tries to write some of the output. */ 1544 1545 int 1546 packet_write_poll(void) 1547 { 1548 int len = buffer_len(&output); 1549 1550 if (len > 0) { 1551 len = write(connection_out, buffer_ptr(&output), len); 1552 if (len == -1) { 1553 if (errno == EINTR || errno == EAGAIN) 1554 return 0; 1555 fatal("Write failed: %.100s", strerror(errno)); 1556 } 1557 if (len == 0) 1558 fatal("Write connection closed"); 1559 buffer_consume(&output, len); 1560 } 1561 return(len); 1562 } 1563 1564 /* 1565 * Calls packet_write_poll repeatedly until all pending output data has been 1566 * written. 1567 */ 1568 1569 int 1570 packet_write_wait(void) 1571 { 1572 fd_set *setp; 1573 int ret, ms_remain; 1574 struct timeval start, timeout, *timeoutp = NULL; 1575 u_int bytes_sent = 0; 1576 1577 setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS), 1578 sizeof(fd_mask)); 1579 bytes_sent += packet_write_poll(); 1580 while (packet_have_data_to_write()) { 1581 memset(setp, 0, howmany(connection_out + 1, NFDBITS) * 1582 sizeof(fd_mask)); 1583 FD_SET(connection_out, setp); 1584 1585 if (packet_timeout_ms > 0) { 1586 ms_remain = packet_timeout_ms; 1587 timeoutp = &timeout; 1588 } 1589 for (;;) { 1590 if (packet_timeout_ms != -1) { 1591 ms_to_timeval(&timeout, ms_remain); 1592 gettimeofday(&start, NULL); 1593 } 1594 if ((ret = select(connection_out + 1, NULL, setp, 1595 NULL, timeoutp)) >= 0) 1596 break; 1597 if (errno != EAGAIN && errno != EINTR) 1598 break; 1599 if (packet_timeout_ms == -1) 1600 continue; 1601 ms_subtract_diff(&start, &ms_remain); 1602 if (ms_remain <= 0) { 1603 ret = 0; 1604 break; 1605 } 1606 } 1607 if (ret == 0) { 1608 logit("Connection to %.200s timed out while " 1609 "waiting to write", get_remote_ipaddr()); 1610 cleanup_exit(255); 1611 } 1612 bytes_sent += packet_write_poll(); 1613 } 1614 xfree(setp); 1615 return (bytes_sent); 1616 } 1617 1618 /* Returns true if there is buffered data to write to the connection. */ 1619 1620 int 1621 packet_have_data_to_write(void) 1622 { 1623 return buffer_len(&output) != 0; 1624 } 1625 1626 /* Returns true if there is not too much data to write to the connection. */ 1627 1628 int 1629 packet_not_very_much_data_to_write(void) 1630 { 1631 if (interactive_mode) 1632 return buffer_len(&output) < 16384; 1633 else 1634 return buffer_len(&output) < 128 * 1024; 1635 } 1636 1637 static void 1638 packet_set_tos(int interactive) 1639 { 1640 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; 1641 1642 if (!packet_connection_is_on_socket() || 1643 !packet_connection_is_ipv4()) 1644 return; 1645 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, 1646 sizeof(tos)) < 0) 1647 error("setsockopt IP_TOS %d: %.100s:", 1648 tos, strerror(errno)); 1649 } 1650 1651 /* Informs that the current session is interactive. Sets IP flags for that. */ 1652 1653 void 1654 packet_set_interactive(int interactive) 1655 { 1656 static int called = 0; 1657 1658 if (called) 1659 return; 1660 called = 1; 1661 1662 /* Record that we are in interactive mode. */ 1663 interactive_mode = interactive; 1664 1665 /* Only set socket options if using a socket. */ 1666 if (!packet_connection_is_on_socket()) 1667 return; 1668 set_nodelay(connection_in); 1669 packet_set_tos(interactive); 1670 } 1671 1672 /* Returns true if the current connection is interactive. */ 1673 1674 int 1675 packet_is_interactive(void) 1676 { 1677 return interactive_mode; 1678 } 1679 1680 int 1681 packet_set_maxsize(u_int s) 1682 { 1683 static int called = 0; 1684 1685 if (called) { 1686 logit("packet_set_maxsize: called twice: old %d new %d", 1687 max_packet_size, s); 1688 return -1; 1689 } 1690 if (s < 4 * 1024 || s > 1024 * 1024) { 1691 logit("packet_set_maxsize: bad size %d", s); 1692 return -1; 1693 } 1694 called = 1; 1695 debug("packet_set_maxsize: setting to %d", s); 1696 max_packet_size = s; 1697 return s; 1698 } 1699 1700 /* roundup current message to pad bytes */ 1701 void 1702 packet_add_padding(u_char pad) 1703 { 1704 extra_pad = pad; 1705 } 1706 1707 /* 1708 * 9.2. Ignored Data Message 1709 * 1710 * byte SSH_MSG_IGNORE 1711 * string data 1712 * 1713 * All implementations MUST understand (and ignore) this message at any 1714 * time (after receiving the protocol version). No implementation is 1715 * required to send them. This message can be used as an additional 1716 * protection measure against advanced traffic analysis techniques. 1717 */ 1718 void 1719 packet_send_ignore(int nbytes) 1720 { 1721 u_int32_t rnd = 0; 1722 int i; 1723 1724 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); 1725 packet_put_int(nbytes); 1726 for (i = 0; i < nbytes; i++) { 1727 if (i % 4 == 0) 1728 rnd = arc4random(); 1729 packet_put_char((u_char)rnd & 0xff); 1730 rnd >>= 8; 1731 } 1732 } 1733 1734 int rekey_requested = 0; 1735 void 1736 packet_request_rekeying(void) 1737 { 1738 rekey_requested = 1; 1739 } 1740 1741 #define MAX_PACKETS (1U<<31) 1742 int 1743 packet_need_rekeying(void) 1744 { 1745 if (datafellows & SSH_BUG_NOREKEY) 1746 return 0; 1747 if (rekey_requested == 1) 1748 { 1749 rekey_requested = 0; 1750 return 1; 1751 } 1752 return 1753 (p_send.packets > MAX_PACKETS) || 1754 (p_read.packets > MAX_PACKETS) || 1755 (max_blocks_out && (p_send.blocks > max_blocks_out)) || 1756 (max_blocks_in && (p_read.blocks > max_blocks_in)); 1757 } 1758 1759 void 1760 packet_set_rekey_limit(u_int32_t bytes) 1761 { 1762 rekey_limit = bytes; 1763 } 1764 1765 void 1766 packet_set_server(void) 1767 { 1768 server_side = 1; 1769 } 1770 1771 void 1772 packet_set_authenticated(void) 1773 { 1774 after_authentication = 1; 1775 } 1776 1777 int 1778 packet_authentication_state(void) 1779 { 1780 return(after_authentication); 1781 } 1782