1 /* $OpenBSD: packet.c,v 1.155 2008/06/13 09:44:36 deraadt 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 <sys/types.h> 41 #include <sys/queue.h> 42 #include <sys/socket.h> 43 #include <sys/time.h> 44 #include <sys/param.h> 45 46 #include <netinet/in_systm.h> 47 #include <netinet/in.h> 48 #include <netinet/ip.h> 49 50 #include <errno.h> 51 #include <stdarg.h> 52 #include <stdio.h> 53 #include <stdlib.h> 54 #include <string.h> 55 #include <unistd.h> 56 #include <signal.h> 57 58 #include "xmalloc.h" 59 #include "buffer.h" 60 #include "packet.h" 61 #include "crc32.h" 62 #include "compress.h" 63 #include "deattack.h" 64 #include "channels.h" 65 #include "compat.h" 66 #include "ssh1.h" 67 #include "ssh2.h" 68 #include "cipher.h" 69 #include "key.h" 70 #include "kex.h" 71 #include "mac.h" 72 #include "log.h" 73 #include "canohost.h" 74 #include "misc.h" 75 #include "ssh.h" 76 77 #ifdef PACKET_DEBUG 78 #define DBG(x) x 79 #else 80 #define DBG(x) 81 #endif 82 83 /* 84 * This variable contains the file descriptors used for communicating with 85 * the other side. connection_in is used for reading; connection_out for 86 * writing. These can be the same descriptor, in which case it is assumed to 87 * be a socket. 88 */ 89 static int connection_in = -1; 90 static int connection_out = -1; 91 92 /* Protocol flags for the remote side. */ 93 static u_int remote_protocol_flags = 0; 94 95 /* Encryption context for receiving data. This is only used for decryption. */ 96 static CipherContext receive_context; 97 98 /* Encryption context for sending data. This is only used for encryption. */ 99 static CipherContext send_context; 100 101 /* Buffer for raw input data from the socket. */ 102 Buffer input; 103 104 /* Buffer for raw output data going to the socket. */ 105 Buffer output; 106 107 /* Buffer for the partial outgoing packet being constructed. */ 108 static Buffer outgoing_packet; 109 110 /* Buffer for the incoming packet currently being processed. */ 111 static Buffer incoming_packet; 112 113 /* Scratch buffer for packet compression/decompression. */ 114 static Buffer compression_buffer; 115 static int compression_buffer_ready = 0; 116 117 /* Flag indicating whether packet compression/decompression is enabled. */ 118 static int packet_compression = 0; 119 120 /* default maximum packet size */ 121 u_int max_packet_size = 32768; 122 123 /* Flag indicating whether this module has been initialized. */ 124 static int initialized = 0; 125 126 /* Set to true if the connection is interactive. */ 127 static int interactive_mode = 0; 128 129 /* Set to true if we are the server side. */ 130 static int server_side = 0; 131 132 /* Set to true if we are authenticated. */ 133 static int after_authentication = 0; 134 135 int keep_alive_timeouts = 0; 136 137 /* Set to the maximum time that we will wait to send or receive a packet */ 138 static int packet_timeout_ms = -1; 139 140 /* Session key information for Encryption and MAC */ 141 Newkeys *newkeys[MODE_MAX]; 142 static struct packet_state { 143 u_int32_t seqnr; 144 u_int32_t packets; 145 u_int64_t blocks; 146 } p_read, p_send; 147 148 static u_int64_t max_blocks_in, max_blocks_out; 149 static u_int32_t rekey_limit; 150 151 /* Session key for protocol v1 */ 152 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; 153 static u_int ssh1_keylen; 154 155 /* roundup current message to extra_pad bytes */ 156 static u_char extra_pad = 0; 157 158 struct packet { 159 TAILQ_ENTRY(packet) next; 160 u_char type; 161 Buffer payload; 162 }; 163 TAILQ_HEAD(, packet) outgoing; 164 165 /* 166 * Sets the descriptors used for communication. Disables encryption until 167 * packet_set_encryption_key is called. 168 */ 169 void 170 packet_set_connection(int fd_in, int fd_out) 171 { 172 Cipher *none = cipher_by_name("none"); 173 174 if (none == NULL) 175 fatal("packet_set_connection: cannot load cipher 'none'"); 176 connection_in = fd_in; 177 connection_out = fd_out; 178 cipher_init(&send_context, none, (const u_char *)"", 179 0, NULL, 0, CIPHER_ENCRYPT); 180 cipher_init(&receive_context, none, (const u_char *)"", 181 0, NULL, 0, CIPHER_DECRYPT); 182 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; 183 if (!initialized) { 184 initialized = 1; 185 buffer_init(&input); 186 buffer_init(&output); 187 buffer_init(&outgoing_packet); 188 buffer_init(&incoming_packet); 189 TAILQ_INIT(&outgoing); 190 } 191 } 192 193 void 194 packet_set_timeout(int timeout, int count) 195 { 196 if (timeout == 0 || count == 0) { 197 packet_timeout_ms = -1; 198 return; 199 } 200 if ((INT_MAX / 1000) / count < timeout) 201 packet_timeout_ms = INT_MAX; 202 else 203 packet_timeout_ms = timeout * count * 1000; 204 } 205 206 /* Returns 1 if remote host is connected via socket, 0 if not. */ 207 208 int 209 packet_connection_is_on_socket(void) 210 { 211 struct sockaddr_storage from, to; 212 socklen_t fromlen, tolen; 213 214 /* filedescriptors in and out are the same, so it's a socket */ 215 if (connection_in == connection_out) 216 return 1; 217 fromlen = sizeof(from); 218 memset(&from, 0, sizeof(from)); 219 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) 220 return 0; 221 tolen = sizeof(to); 222 memset(&to, 0, sizeof(to)); 223 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) 224 return 0; 225 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) 226 return 0; 227 if (from.ss_family != AF_INET && from.ss_family != AF_INET6) 228 return 0; 229 return 1; 230 } 231 232 /* 233 * Exports an IV from the CipherContext required to export the key 234 * state back from the unprivileged child to the privileged parent 235 * process. 236 */ 237 238 void 239 packet_get_keyiv(int mode, u_char *iv, u_int len) 240 { 241 CipherContext *cc; 242 243 if (mode == MODE_OUT) 244 cc = &send_context; 245 else 246 cc = &receive_context; 247 248 cipher_get_keyiv(cc, iv, len); 249 } 250 251 int 252 packet_get_keycontext(int mode, u_char *dat) 253 { 254 CipherContext *cc; 255 256 if (mode == MODE_OUT) 257 cc = &send_context; 258 else 259 cc = &receive_context; 260 261 return (cipher_get_keycontext(cc, dat)); 262 } 263 264 void 265 packet_set_keycontext(int mode, u_char *dat) 266 { 267 CipherContext *cc; 268 269 if (mode == MODE_OUT) 270 cc = &send_context; 271 else 272 cc = &receive_context; 273 274 cipher_set_keycontext(cc, dat); 275 } 276 277 int 278 packet_get_keyiv_len(int mode) 279 { 280 CipherContext *cc; 281 282 if (mode == MODE_OUT) 283 cc = &send_context; 284 else 285 cc = &receive_context; 286 287 return (cipher_get_keyiv_len(cc)); 288 } 289 290 void 291 packet_set_iv(int mode, u_char *dat) 292 { 293 CipherContext *cc; 294 295 if (mode == MODE_OUT) 296 cc = &send_context; 297 else 298 cc = &receive_context; 299 300 cipher_set_keyiv(cc, dat); 301 } 302 303 int 304 packet_get_ssh1_cipher(void) 305 { 306 return (cipher_get_number(receive_context.cipher)); 307 } 308 309 void 310 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets) 311 { 312 struct packet_state *state; 313 314 state = (mode == MODE_IN) ? &p_read : &p_send; 315 *seqnr = state->seqnr; 316 *blocks = state->blocks; 317 *packets = state->packets; 318 } 319 320 void 321 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets) 322 { 323 struct packet_state *state; 324 325 state = (mode == MODE_IN) ? &p_read : &p_send; 326 state->seqnr = seqnr; 327 state->blocks = blocks; 328 state->packets = packets; 329 } 330 331 /* returns 1 if connection is via ipv4 */ 332 333 int 334 packet_connection_is_ipv4(void) 335 { 336 struct sockaddr_storage to; 337 socklen_t tolen = sizeof(to); 338 339 memset(&to, 0, sizeof(to)); 340 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) 341 return 0; 342 if (to.ss_family != AF_INET) 343 return 0; 344 return 1; 345 } 346 347 /* Sets the connection into non-blocking mode. */ 348 349 void 350 packet_set_nonblocking(void) 351 { 352 /* Set the socket into non-blocking mode. */ 353 set_nonblock(connection_in); 354 355 if (connection_out != connection_in) 356 set_nonblock(connection_out); 357 } 358 359 /* Returns the socket used for reading. */ 360 361 int 362 packet_get_connection_in(void) 363 { 364 return connection_in; 365 } 366 367 /* Returns the descriptor used for writing. */ 368 369 int 370 packet_get_connection_out(void) 371 { 372 return connection_out; 373 } 374 375 /* Closes the connection and clears and frees internal data structures. */ 376 377 void 378 packet_close(void) 379 { 380 if (!initialized) 381 return; 382 initialized = 0; 383 if (connection_in == connection_out) { 384 shutdown(connection_out, SHUT_RDWR); 385 close(connection_out); 386 } else { 387 close(connection_in); 388 close(connection_out); 389 } 390 buffer_free(&input); 391 buffer_free(&output); 392 buffer_free(&outgoing_packet); 393 buffer_free(&incoming_packet); 394 if (compression_buffer_ready) { 395 buffer_free(&compression_buffer); 396 buffer_compress_uninit(); 397 } 398 cipher_cleanup(&send_context); 399 cipher_cleanup(&receive_context); 400 } 401 402 /* Sets remote side protocol flags. */ 403 404 void 405 packet_set_protocol_flags(u_int protocol_flags) 406 { 407 remote_protocol_flags = protocol_flags; 408 } 409 410 /* Returns the remote protocol flags set earlier by the above function. */ 411 412 u_int 413 packet_get_protocol_flags(void) 414 { 415 return remote_protocol_flags; 416 } 417 418 /* 419 * Starts packet compression from the next packet on in both directions. 420 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. 421 */ 422 423 static void 424 packet_init_compression(void) 425 { 426 if (compression_buffer_ready == 1) 427 return; 428 compression_buffer_ready = 1; 429 buffer_init(&compression_buffer); 430 } 431 432 void 433 packet_start_compression(int level) 434 { 435 if (packet_compression && !compat20) 436 fatal("Compression already enabled."); 437 packet_compression = 1; 438 packet_init_compression(); 439 buffer_compress_init_send(level); 440 buffer_compress_init_recv(); 441 } 442 443 /* 444 * Causes any further packets to be encrypted using the given key. The same 445 * key is used for both sending and reception. However, both directions are 446 * encrypted independently of each other. 447 */ 448 449 void 450 packet_set_encryption_key(const u_char *key, u_int keylen, 451 int number) 452 { 453 Cipher *cipher = cipher_by_number(number); 454 455 if (cipher == NULL) 456 fatal("packet_set_encryption_key: unknown cipher number %d", number); 457 if (keylen < 20) 458 fatal("packet_set_encryption_key: keylen too small: %d", keylen); 459 if (keylen > SSH_SESSION_KEY_LENGTH) 460 fatal("packet_set_encryption_key: keylen too big: %d", keylen); 461 memcpy(ssh1_key, key, keylen); 462 ssh1_keylen = keylen; 463 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); 464 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); 465 } 466 467 u_int 468 packet_get_encryption_key(u_char *key) 469 { 470 if (key == NULL) 471 return (ssh1_keylen); 472 memcpy(key, ssh1_key, ssh1_keylen); 473 return (ssh1_keylen); 474 } 475 476 /* Start constructing a packet to send. */ 477 void 478 packet_start(u_char type) 479 { 480 u_char buf[9]; 481 int len; 482 483 DBG(debug("packet_start[%d]", type)); 484 len = compat20 ? 6 : 9; 485 memset(buf, 0, len - 1); 486 buf[len - 1] = type; 487 buffer_clear(&outgoing_packet); 488 buffer_append(&outgoing_packet, buf, len); 489 } 490 491 /* Append payload. */ 492 void 493 packet_put_char(int value) 494 { 495 char ch = value; 496 497 buffer_append(&outgoing_packet, &ch, 1); 498 } 499 500 void 501 packet_put_int(u_int value) 502 { 503 buffer_put_int(&outgoing_packet, value); 504 } 505 506 void 507 packet_put_string(const void *buf, u_int len) 508 { 509 buffer_put_string(&outgoing_packet, buf, len); 510 } 511 512 void 513 packet_put_cstring(const char *str) 514 { 515 buffer_put_cstring(&outgoing_packet, str); 516 } 517 518 void 519 packet_put_raw(const void *buf, u_int len) 520 { 521 buffer_append(&outgoing_packet, buf, len); 522 } 523 524 void 525 packet_put_bignum(BIGNUM * value) 526 { 527 buffer_put_bignum(&outgoing_packet, value); 528 } 529 530 void 531 packet_put_bignum2(BIGNUM * value) 532 { 533 buffer_put_bignum2(&outgoing_packet, value); 534 } 535 536 /* 537 * Finalizes and sends the packet. If the encryption key has been set, 538 * encrypts the packet before sending. 539 */ 540 541 static void 542 packet_send1(void) 543 { 544 u_char buf[8], *cp; 545 int i, padding, len; 546 u_int checksum; 547 u_int32_t rnd = 0; 548 549 /* 550 * If using packet compression, compress the payload of the outgoing 551 * packet. 552 */ 553 if (packet_compression) { 554 buffer_clear(&compression_buffer); 555 /* Skip padding. */ 556 buffer_consume(&outgoing_packet, 8); 557 /* padding */ 558 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); 559 buffer_compress(&outgoing_packet, &compression_buffer); 560 buffer_clear(&outgoing_packet); 561 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 562 buffer_len(&compression_buffer)); 563 } 564 /* Compute packet length without padding (add checksum, remove padding). */ 565 len = buffer_len(&outgoing_packet) + 4 - 8; 566 567 /* Insert padding. Initialized to zero in packet_start1() */ 568 padding = 8 - len % 8; 569 if (!send_context.plaintext) { 570 cp = buffer_ptr(&outgoing_packet); 571 for (i = 0; i < padding; i++) { 572 if (i % 4 == 0) 573 rnd = arc4random(); 574 cp[7 - i] = rnd & 0xff; 575 rnd >>= 8; 576 } 577 } 578 buffer_consume(&outgoing_packet, 8 - padding); 579 580 /* Add check bytes. */ 581 checksum = ssh_crc32(buffer_ptr(&outgoing_packet), 582 buffer_len(&outgoing_packet)); 583 put_u32(buf, checksum); 584 buffer_append(&outgoing_packet, buf, 4); 585 586 #ifdef PACKET_DEBUG 587 fprintf(stderr, "packet_send plain: "); 588 buffer_dump(&outgoing_packet); 589 #endif 590 591 /* Append to output. */ 592 put_u32(buf, len); 593 buffer_append(&output, buf, 4); 594 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 595 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 596 buffer_len(&outgoing_packet)); 597 598 #ifdef PACKET_DEBUG 599 fprintf(stderr, "encrypted: "); 600 buffer_dump(&output); 601 #endif 602 603 buffer_clear(&outgoing_packet); 604 605 /* 606 * Note that the packet is now only buffered in output. It won't be 607 * actually sent until packet_write_wait or packet_write_poll is 608 * called. 609 */ 610 } 611 612 void 613 set_newkeys(int mode) 614 { 615 Enc *enc; 616 Mac *mac; 617 Comp *comp; 618 CipherContext *cc; 619 u_int64_t *max_blocks; 620 int crypt_type; 621 622 debug2("set_newkeys: mode %d", mode); 623 624 if (mode == MODE_OUT) { 625 cc = &send_context; 626 crypt_type = CIPHER_ENCRYPT; 627 p_send.packets = p_send.blocks = 0; 628 max_blocks = &max_blocks_out; 629 } else { 630 cc = &receive_context; 631 crypt_type = CIPHER_DECRYPT; 632 p_read.packets = p_read.blocks = 0; 633 max_blocks = &max_blocks_in; 634 } 635 if (newkeys[mode] != NULL) { 636 debug("set_newkeys: rekeying"); 637 cipher_cleanup(cc); 638 enc = &newkeys[mode]->enc; 639 mac = &newkeys[mode]->mac; 640 comp = &newkeys[mode]->comp; 641 mac_clear(mac); 642 xfree(enc->name); 643 xfree(enc->iv); 644 xfree(enc->key); 645 xfree(mac->name); 646 xfree(mac->key); 647 xfree(comp->name); 648 xfree(newkeys[mode]); 649 } 650 newkeys[mode] = kex_get_newkeys(mode); 651 if (newkeys[mode] == NULL) 652 fatal("newkeys: no keys for mode %d", mode); 653 enc = &newkeys[mode]->enc; 654 mac = &newkeys[mode]->mac; 655 comp = &newkeys[mode]->comp; 656 if (mac_init(mac) == 0) 657 mac->enabled = 1; 658 DBG(debug("cipher_init_context: %d", mode)); 659 cipher_init(cc, enc->cipher, enc->key, enc->key_len, 660 enc->iv, enc->block_size, crypt_type); 661 /* Deleting the keys does not gain extra security */ 662 /* memset(enc->iv, 0, enc->block_size); 663 memset(enc->key, 0, enc->key_len); 664 memset(mac->key, 0, mac->key_len); */ 665 if ((comp->type == COMP_ZLIB || 666 (comp->type == COMP_DELAYED && after_authentication)) && 667 comp->enabled == 0) { 668 packet_init_compression(); 669 if (mode == MODE_OUT) 670 buffer_compress_init_send(6); 671 else 672 buffer_compress_init_recv(); 673 comp->enabled = 1; 674 } 675 /* 676 * The 2^(blocksize*2) limit is too expensive for 3DES, 677 * blowfish, etc, so enforce a 1GB limit for small blocksizes. 678 */ 679 if (enc->block_size >= 16) 680 *max_blocks = (u_int64_t)1 << (enc->block_size*2); 681 else 682 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; 683 if (rekey_limit) 684 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); 685 } 686 687 /* 688 * Delayed compression for SSH2 is enabled after authentication: 689 * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent, 690 * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received. 691 */ 692 static void 693 packet_enable_delayed_compress(void) 694 { 695 Comp *comp = NULL; 696 int mode; 697 698 /* 699 * Remember that we are past the authentication step, so rekeying 700 * with COMP_DELAYED will turn on compression immediately. 701 */ 702 after_authentication = 1; 703 for (mode = 0; mode < MODE_MAX; mode++) { 704 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */ 705 if (newkeys[mode] == NULL) 706 continue; 707 comp = &newkeys[mode]->comp; 708 if (comp && !comp->enabled && comp->type == COMP_DELAYED) { 709 packet_init_compression(); 710 if (mode == MODE_OUT) 711 buffer_compress_init_send(6); 712 else 713 buffer_compress_init_recv(); 714 comp->enabled = 1; 715 } 716 } 717 } 718 719 /* 720 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) 721 */ 722 static void 723 packet_send2_wrapped(void) 724 { 725 u_char type, *cp, *macbuf = NULL; 726 u_char padlen, pad; 727 u_int packet_length = 0; 728 u_int i, len; 729 u_int32_t rnd = 0; 730 Enc *enc = NULL; 731 Mac *mac = NULL; 732 Comp *comp = NULL; 733 int block_size; 734 735 if (newkeys[MODE_OUT] != NULL) { 736 enc = &newkeys[MODE_OUT]->enc; 737 mac = &newkeys[MODE_OUT]->mac; 738 comp = &newkeys[MODE_OUT]->comp; 739 } 740 block_size = enc ? enc->block_size : 8; 741 742 cp = buffer_ptr(&outgoing_packet); 743 type = cp[5]; 744 745 #ifdef PACKET_DEBUG 746 fprintf(stderr, "plain: "); 747 buffer_dump(&outgoing_packet); 748 #endif 749 750 if (comp && comp->enabled) { 751 len = buffer_len(&outgoing_packet); 752 /* skip header, compress only payload */ 753 buffer_consume(&outgoing_packet, 5); 754 buffer_clear(&compression_buffer); 755 buffer_compress(&outgoing_packet, &compression_buffer); 756 buffer_clear(&outgoing_packet); 757 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); 758 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 759 buffer_len(&compression_buffer)); 760 DBG(debug("compression: raw %d compressed %d", len, 761 buffer_len(&outgoing_packet))); 762 } 763 764 /* sizeof (packet_len + pad_len + payload) */ 765 len = buffer_len(&outgoing_packet); 766 767 /* 768 * calc size of padding, alloc space, get random data, 769 * minimum padding is 4 bytes 770 */ 771 padlen = block_size - (len % block_size); 772 if (padlen < 4) 773 padlen += block_size; 774 if (extra_pad) { 775 /* will wrap if extra_pad+padlen > 255 */ 776 extra_pad = roundup(extra_pad, block_size); 777 pad = extra_pad - ((len + padlen) % extra_pad); 778 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", 779 pad, len, padlen, extra_pad); 780 padlen += pad; 781 extra_pad = 0; 782 } 783 cp = buffer_append_space(&outgoing_packet, padlen); 784 if (enc && !send_context.plaintext) { 785 /* random padding */ 786 for (i = 0; i < padlen; i++) { 787 if (i % 4 == 0) 788 rnd = arc4random(); 789 cp[i] = rnd & 0xff; 790 rnd >>= 8; 791 } 792 } else { 793 /* clear padding */ 794 memset(cp, 0, padlen); 795 } 796 /* packet_length includes payload, padding and padding length field */ 797 packet_length = buffer_len(&outgoing_packet) - 4; 798 cp = buffer_ptr(&outgoing_packet); 799 put_u32(cp, packet_length); 800 cp[4] = padlen; 801 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); 802 803 /* compute MAC over seqnr and packet(length fields, payload, padding) */ 804 if (mac && mac->enabled) { 805 macbuf = mac_compute(mac, p_send.seqnr, 806 buffer_ptr(&outgoing_packet), 807 buffer_len(&outgoing_packet)); 808 DBG(debug("done calc MAC out #%d", p_send.seqnr)); 809 } 810 /* encrypt packet and append to output buffer. */ 811 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 812 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 813 buffer_len(&outgoing_packet)); 814 /* append unencrypted MAC */ 815 if (mac && mac->enabled) 816 buffer_append(&output, macbuf, mac->mac_len); 817 #ifdef PACKET_DEBUG 818 fprintf(stderr, "encrypted: "); 819 buffer_dump(&output); 820 #endif 821 /* increment sequence number for outgoing packets */ 822 if (++p_send.seqnr == 0) 823 logit("outgoing seqnr wraps around"); 824 if (++p_send.packets == 0) 825 if (!(datafellows & SSH_BUG_NOREKEY)) 826 fatal("XXX too many packets with same key"); 827 p_send.blocks += (packet_length + 4) / block_size; 828 buffer_clear(&outgoing_packet); 829 830 if (type == SSH2_MSG_NEWKEYS) 831 set_newkeys(MODE_OUT); 832 else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side) 833 packet_enable_delayed_compress(); 834 } 835 836 static void 837 packet_send2(void) 838 { 839 static int rekeying = 0; 840 struct packet *p; 841 u_char type, *cp; 842 843 cp = buffer_ptr(&outgoing_packet); 844 type = cp[5]; 845 846 /* during rekeying we can only send key exchange messages */ 847 if (rekeying) { 848 if (!((type >= SSH2_MSG_TRANSPORT_MIN) && 849 (type <= SSH2_MSG_TRANSPORT_MAX))) { 850 debug("enqueue packet: %u", type); 851 p = xmalloc(sizeof(*p)); 852 p->type = type; 853 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); 854 buffer_init(&outgoing_packet); 855 TAILQ_INSERT_TAIL(&outgoing, p, next); 856 return; 857 } 858 } 859 860 /* rekeying starts with sending KEXINIT */ 861 if (type == SSH2_MSG_KEXINIT) 862 rekeying = 1; 863 864 packet_send2_wrapped(); 865 866 /* after a NEWKEYS message we can send the complete queue */ 867 if (type == SSH2_MSG_NEWKEYS) { 868 rekeying = 0; 869 while ((p = TAILQ_FIRST(&outgoing))) { 870 type = p->type; 871 debug("dequeue packet: %u", type); 872 buffer_free(&outgoing_packet); 873 memcpy(&outgoing_packet, &p->payload, 874 sizeof(Buffer)); 875 TAILQ_REMOVE(&outgoing, p, next); 876 xfree(p); 877 packet_send2_wrapped(); 878 } 879 } 880 } 881 882 void 883 packet_send(void) 884 { 885 if (compat20) 886 packet_send2(); 887 else 888 packet_send1(); 889 DBG(debug("packet_send done")); 890 } 891 892 /* 893 * Waits until a packet has been received, and returns its type. Note that 894 * no other data is processed until this returns, so this function should not 895 * be used during the interactive session. 896 */ 897 898 int 899 packet_read_seqnr(u_int32_t *seqnr_p) 900 { 901 int type, len, ret, ms_remain; 902 fd_set *setp; 903 char buf[8192]; 904 struct timeval timeout, start, *timeoutp = NULL; 905 906 DBG(debug("packet_read()")); 907 908 setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS), 909 sizeof(fd_mask)); 910 911 /* Since we are blocking, ensure that all written packets have been sent. */ 912 packet_write_wait(); 913 914 /* Stay in the loop until we have received a complete packet. */ 915 for (;;) { 916 /* Try to read a packet from the buffer. */ 917 type = packet_read_poll_seqnr(seqnr_p); 918 if (!compat20 && ( 919 type == SSH_SMSG_SUCCESS 920 || type == SSH_SMSG_FAILURE 921 || type == SSH_CMSG_EOF 922 || type == SSH_CMSG_EXIT_CONFIRMATION)) 923 packet_check_eom(); 924 /* If we got a packet, return it. */ 925 if (type != SSH_MSG_NONE) { 926 xfree(setp); 927 return type; 928 } 929 /* 930 * Otherwise, wait for some data to arrive, add it to the 931 * buffer, and try again. 932 */ 933 memset(setp, 0, howmany(connection_in + 1, NFDBITS) * 934 sizeof(fd_mask)); 935 FD_SET(connection_in, setp); 936 937 if (packet_timeout_ms > 0) { 938 ms_remain = packet_timeout_ms; 939 timeoutp = &timeout; 940 } 941 /* Wait for some data to arrive. */ 942 for (;;) { 943 if (packet_timeout_ms != -1) { 944 ms_to_timeval(&timeout, ms_remain); 945 gettimeofday(&start, NULL); 946 } 947 if ((ret = select(connection_in + 1, setp, NULL, 948 NULL, timeoutp)) >= 0) 949 break; 950 if (errno != EAGAIN && errno != EINTR) 951 break; 952 if (packet_timeout_ms == -1) 953 continue; 954 ms_subtract_diff(&start, &ms_remain); 955 if (ms_remain <= 0) { 956 ret = 0; 957 break; 958 } 959 } 960 if (ret == 0) { 961 logit("Connection to %.200s timed out while " 962 "waiting to read", get_remote_ipaddr()); 963 cleanup_exit(255); 964 } 965 /* Read data from the socket. */ 966 len = read(connection_in, buf, sizeof(buf)); 967 if (len == 0) { 968 logit("Connection closed by %.200s", get_remote_ipaddr()); 969 cleanup_exit(255); 970 } 971 if (len < 0) 972 fatal("Read from socket failed: %.100s", strerror(errno)); 973 /* Append it to the buffer. */ 974 packet_process_incoming(buf, len); 975 } 976 /* NOTREACHED */ 977 } 978 979 int 980 packet_read(void) 981 { 982 return packet_read_seqnr(NULL); 983 } 984 985 /* 986 * Waits until a packet has been received, verifies that its type matches 987 * that given, and gives a fatal error and exits if there is a mismatch. 988 */ 989 990 void 991 packet_read_expect(int expected_type) 992 { 993 int type; 994 995 type = packet_read(); 996 if (type != expected_type) 997 packet_disconnect("Protocol error: expected packet type %d, got %d", 998 expected_type, type); 999 } 1000 1001 /* Checks if a full packet is available in the data received so far via 1002 * packet_process_incoming. If so, reads the packet; otherwise returns 1003 * SSH_MSG_NONE. This does not wait for data from the connection. 1004 * 1005 * SSH_MSG_DISCONNECT is handled specially here. Also, 1006 * SSH_MSG_IGNORE messages are skipped by this function and are never returned 1007 * to higher levels. 1008 */ 1009 1010 static int 1011 packet_read_poll1(void) 1012 { 1013 u_int len, padded_len; 1014 u_char *cp, type; 1015 u_int checksum, stored_checksum; 1016 1017 /* Check if input size is less than minimum packet size. */ 1018 if (buffer_len(&input) < 4 + 8) 1019 return SSH_MSG_NONE; 1020 /* Get length of incoming packet. */ 1021 cp = buffer_ptr(&input); 1022 len = get_u32(cp); 1023 if (len < 1 + 2 + 2 || len > 256 * 1024) 1024 packet_disconnect("Bad packet length %u.", len); 1025 padded_len = (len + 8) & ~7; 1026 1027 /* Check if the packet has been entirely received. */ 1028 if (buffer_len(&input) < 4 + padded_len) 1029 return SSH_MSG_NONE; 1030 1031 /* The entire packet is in buffer. */ 1032 1033 /* Consume packet length. */ 1034 buffer_consume(&input, 4); 1035 1036 /* 1037 * Cryptographic attack detector for ssh 1038 * (C)1998 CORE-SDI, Buenos Aires Argentina 1039 * Ariel Futoransky(futo@core-sdi.com) 1040 */ 1041 if (!receive_context.plaintext) { 1042 switch (detect_attack(buffer_ptr(&input), padded_len)) { 1043 case DEATTACK_DETECTED: 1044 packet_disconnect("crc32 compensation attack: " 1045 "network attack detected"); 1046 case DEATTACK_DOS_DETECTED: 1047 packet_disconnect("deattack denial of " 1048 "service detected"); 1049 } 1050 } 1051 1052 /* Decrypt data to incoming_packet. */ 1053 buffer_clear(&incoming_packet); 1054 cp = buffer_append_space(&incoming_packet, padded_len); 1055 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); 1056 1057 buffer_consume(&input, padded_len); 1058 1059 #ifdef PACKET_DEBUG 1060 fprintf(stderr, "read_poll plain: "); 1061 buffer_dump(&incoming_packet); 1062 #endif 1063 1064 /* Compute packet checksum. */ 1065 checksum = ssh_crc32(buffer_ptr(&incoming_packet), 1066 buffer_len(&incoming_packet) - 4); 1067 1068 /* Skip padding. */ 1069 buffer_consume(&incoming_packet, 8 - len % 8); 1070 1071 /* Test check bytes. */ 1072 if (len != buffer_len(&incoming_packet)) 1073 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", 1074 len, buffer_len(&incoming_packet)); 1075 1076 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; 1077 stored_checksum = get_u32(cp); 1078 if (checksum != stored_checksum) 1079 packet_disconnect("Corrupted check bytes on input."); 1080 buffer_consume_end(&incoming_packet, 4); 1081 1082 if (packet_compression) { 1083 buffer_clear(&compression_buffer); 1084 buffer_uncompress(&incoming_packet, &compression_buffer); 1085 buffer_clear(&incoming_packet); 1086 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1087 buffer_len(&compression_buffer)); 1088 } 1089 type = buffer_get_char(&incoming_packet); 1090 if (type < SSH_MSG_MIN || type > SSH_MSG_MAX) 1091 packet_disconnect("Invalid ssh1 packet type: %d", type); 1092 return type; 1093 } 1094 1095 static int 1096 packet_read_poll2(u_int32_t *seqnr_p) 1097 { 1098 static u_int packet_length = 0; 1099 u_int padlen, need; 1100 u_char *macbuf, *cp, type; 1101 u_int maclen, block_size; 1102 Enc *enc = NULL; 1103 Mac *mac = NULL; 1104 Comp *comp = NULL; 1105 1106 if (newkeys[MODE_IN] != NULL) { 1107 enc = &newkeys[MODE_IN]->enc; 1108 mac = &newkeys[MODE_IN]->mac; 1109 comp = &newkeys[MODE_IN]->comp; 1110 } 1111 maclen = mac && mac->enabled ? mac->mac_len : 0; 1112 block_size = enc ? enc->block_size : 8; 1113 1114 if (packet_length == 0) { 1115 /* 1116 * check if input size is less than the cipher block size, 1117 * decrypt first block and extract length of incoming packet 1118 */ 1119 if (buffer_len(&input) < block_size) 1120 return SSH_MSG_NONE; 1121 buffer_clear(&incoming_packet); 1122 cp = buffer_append_space(&incoming_packet, block_size); 1123 cipher_crypt(&receive_context, cp, buffer_ptr(&input), 1124 block_size); 1125 cp = buffer_ptr(&incoming_packet); 1126 packet_length = get_u32(cp); 1127 if (packet_length < 1 + 4 || packet_length > 256 * 1024) { 1128 #ifdef PACKET_DEBUG 1129 buffer_dump(&incoming_packet); 1130 #endif 1131 packet_disconnect("Bad packet length %u.", packet_length); 1132 } 1133 DBG(debug("input: packet len %u", packet_length+4)); 1134 buffer_consume(&input, block_size); 1135 } 1136 /* we have a partial packet of block_size bytes */ 1137 need = 4 + packet_length - block_size; 1138 DBG(debug("partial packet %d, need %d, maclen %d", block_size, 1139 need, maclen)); 1140 if (need % block_size != 0) 1141 fatal("padding error: need %d block %d mod %d", 1142 need, block_size, need % block_size); 1143 /* 1144 * check if the entire packet has been received and 1145 * decrypt into incoming_packet 1146 */ 1147 if (buffer_len(&input) < need + maclen) 1148 return SSH_MSG_NONE; 1149 #ifdef PACKET_DEBUG 1150 fprintf(stderr, "read_poll enc/full: "); 1151 buffer_dump(&input); 1152 #endif 1153 cp = buffer_append_space(&incoming_packet, need); 1154 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); 1155 buffer_consume(&input, need); 1156 /* 1157 * compute MAC over seqnr and packet, 1158 * increment sequence number for incoming packet 1159 */ 1160 if (mac && mac->enabled) { 1161 macbuf = mac_compute(mac, p_read.seqnr, 1162 buffer_ptr(&incoming_packet), 1163 buffer_len(&incoming_packet)); 1164 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) 1165 packet_disconnect("Corrupted MAC on input."); 1166 DBG(debug("MAC #%d ok", p_read.seqnr)); 1167 buffer_consume(&input, mac->mac_len); 1168 } 1169 if (seqnr_p != NULL) 1170 *seqnr_p = p_read.seqnr; 1171 if (++p_read.seqnr == 0) 1172 logit("incoming seqnr wraps around"); 1173 if (++p_read.packets == 0) 1174 if (!(datafellows & SSH_BUG_NOREKEY)) 1175 fatal("XXX too many packets with same key"); 1176 p_read.blocks += (packet_length + 4) / block_size; 1177 1178 /* get padlen */ 1179 cp = buffer_ptr(&incoming_packet); 1180 padlen = cp[4]; 1181 DBG(debug("input: padlen %d", padlen)); 1182 if (padlen < 4) 1183 packet_disconnect("Corrupted padlen %d on input.", padlen); 1184 1185 /* skip packet size + padlen, discard padding */ 1186 buffer_consume(&incoming_packet, 4 + 1); 1187 buffer_consume_end(&incoming_packet, padlen); 1188 1189 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); 1190 if (comp && comp->enabled) { 1191 buffer_clear(&compression_buffer); 1192 buffer_uncompress(&incoming_packet, &compression_buffer); 1193 buffer_clear(&incoming_packet); 1194 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1195 buffer_len(&compression_buffer)); 1196 DBG(debug("input: len after de-compress %d", 1197 buffer_len(&incoming_packet))); 1198 } 1199 /* 1200 * get packet type, implies consume. 1201 * return length of payload (without type field) 1202 */ 1203 type = buffer_get_char(&incoming_packet); 1204 if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN) 1205 packet_disconnect("Invalid ssh2 packet type: %d", type); 1206 if (type == SSH2_MSG_NEWKEYS) 1207 set_newkeys(MODE_IN); 1208 else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side) 1209 packet_enable_delayed_compress(); 1210 #ifdef PACKET_DEBUG 1211 fprintf(stderr, "read/plain[%d]:\r\n", type); 1212 buffer_dump(&incoming_packet); 1213 #endif 1214 /* reset for next packet */ 1215 packet_length = 0; 1216 return type; 1217 } 1218 1219 int 1220 packet_read_poll_seqnr(u_int32_t *seqnr_p) 1221 { 1222 u_int reason, seqnr; 1223 u_char type; 1224 char *msg; 1225 1226 for (;;) { 1227 if (compat20) { 1228 type = packet_read_poll2(seqnr_p); 1229 if (type) { 1230 keep_alive_timeouts = 0; 1231 DBG(debug("received packet type %d", type)); 1232 } 1233 switch (type) { 1234 case SSH2_MSG_IGNORE: 1235 debug3("Received SSH2_MSG_IGNORE"); 1236 break; 1237 case SSH2_MSG_DEBUG: 1238 packet_get_char(); 1239 msg = packet_get_string(NULL); 1240 debug("Remote: %.900s", msg); 1241 xfree(msg); 1242 msg = packet_get_string(NULL); 1243 xfree(msg); 1244 break; 1245 case SSH2_MSG_DISCONNECT: 1246 reason = packet_get_int(); 1247 msg = packet_get_string(NULL); 1248 logit("Received disconnect from %s: %u: %.400s", 1249 get_remote_ipaddr(), reason, msg); 1250 xfree(msg); 1251 cleanup_exit(255); 1252 break; 1253 case SSH2_MSG_UNIMPLEMENTED: 1254 seqnr = packet_get_int(); 1255 debug("Received SSH2_MSG_UNIMPLEMENTED for %u", 1256 seqnr); 1257 break; 1258 default: 1259 return type; 1260 } 1261 } else { 1262 type = packet_read_poll1(); 1263 switch (type) { 1264 case SSH_MSG_IGNORE: 1265 break; 1266 case SSH_MSG_DEBUG: 1267 msg = packet_get_string(NULL); 1268 debug("Remote: %.900s", msg); 1269 xfree(msg); 1270 break; 1271 case SSH_MSG_DISCONNECT: 1272 msg = packet_get_string(NULL); 1273 logit("Received disconnect from %s: %.400s", 1274 get_remote_ipaddr(), msg); 1275 cleanup_exit(255); 1276 break; 1277 default: 1278 if (type) 1279 DBG(debug("received packet type %d", type)); 1280 return type; 1281 } 1282 } 1283 } 1284 } 1285 1286 int 1287 packet_read_poll(void) 1288 { 1289 return packet_read_poll_seqnr(NULL); 1290 } 1291 1292 /* 1293 * Buffers the given amount of input characters. This is intended to be used 1294 * together with packet_read_poll. 1295 */ 1296 1297 void 1298 packet_process_incoming(const char *buf, u_int len) 1299 { 1300 buffer_append(&input, buf, len); 1301 } 1302 1303 /* Returns a character from the packet. */ 1304 1305 u_int 1306 packet_get_char(void) 1307 { 1308 char ch; 1309 1310 buffer_get(&incoming_packet, &ch, 1); 1311 return (u_char) ch; 1312 } 1313 1314 /* Returns an integer from the packet data. */ 1315 1316 u_int 1317 packet_get_int(void) 1318 { 1319 return buffer_get_int(&incoming_packet); 1320 } 1321 1322 /* 1323 * Returns an arbitrary precision integer from the packet data. The integer 1324 * must have been initialized before this call. 1325 */ 1326 1327 void 1328 packet_get_bignum(BIGNUM * value) 1329 { 1330 buffer_get_bignum(&incoming_packet, value); 1331 } 1332 1333 void 1334 packet_get_bignum2(BIGNUM * value) 1335 { 1336 buffer_get_bignum2(&incoming_packet, value); 1337 } 1338 1339 void * 1340 packet_get_raw(u_int *length_ptr) 1341 { 1342 u_int bytes = buffer_len(&incoming_packet); 1343 1344 if (length_ptr != NULL) 1345 *length_ptr = bytes; 1346 return buffer_ptr(&incoming_packet); 1347 } 1348 1349 int 1350 packet_remaining(void) 1351 { 1352 return buffer_len(&incoming_packet); 1353 } 1354 1355 /* 1356 * Returns a string from the packet data. The string is allocated using 1357 * xmalloc; it is the responsibility of the calling program to free it when 1358 * no longer needed. The length_ptr argument may be NULL, or point to an 1359 * integer into which the length of the string is stored. 1360 */ 1361 1362 void * 1363 packet_get_string(u_int *length_ptr) 1364 { 1365 return buffer_get_string(&incoming_packet, length_ptr); 1366 } 1367 1368 void * 1369 packet_get_string_ptr(u_int *length_ptr) 1370 { 1371 return buffer_get_string_ptr(&incoming_packet, length_ptr); 1372 } 1373 1374 /* 1375 * Sends a diagnostic message from the server to the client. This message 1376 * can be sent at any time (but not while constructing another message). The 1377 * message is printed immediately, but only if the client is being executed 1378 * in verbose mode. These messages are primarily intended to ease debugging 1379 * authentication problems. The length of the formatted message must not 1380 * exceed 1024 bytes. This will automatically call packet_write_wait. 1381 */ 1382 1383 void 1384 packet_send_debug(const char *fmt,...) 1385 { 1386 char buf[1024]; 1387 va_list args; 1388 1389 if (compat20 && (datafellows & SSH_BUG_DEBUG)) 1390 return; 1391 1392 va_start(args, fmt); 1393 vsnprintf(buf, sizeof(buf), fmt, args); 1394 va_end(args); 1395 1396 if (compat20) { 1397 packet_start(SSH2_MSG_DEBUG); 1398 packet_put_char(0); /* bool: always display */ 1399 packet_put_cstring(buf); 1400 packet_put_cstring(""); 1401 } else { 1402 packet_start(SSH_MSG_DEBUG); 1403 packet_put_cstring(buf); 1404 } 1405 packet_send(); 1406 packet_write_wait(); 1407 } 1408 1409 /* 1410 * Logs the error plus constructs and sends a disconnect packet, closes the 1411 * connection, and exits. This function never returns. The error message 1412 * should not contain a newline. The length of the formatted message must 1413 * not exceed 1024 bytes. 1414 */ 1415 1416 void 1417 packet_disconnect(const char *fmt,...) 1418 { 1419 char buf[1024]; 1420 va_list args; 1421 static int disconnecting = 0; 1422 1423 if (disconnecting) /* Guard against recursive invocations. */ 1424 fatal("packet_disconnect called recursively."); 1425 disconnecting = 1; 1426 1427 /* 1428 * Format the message. Note that the caller must make sure the 1429 * message is of limited size. 1430 */ 1431 va_start(args, fmt); 1432 vsnprintf(buf, sizeof(buf), fmt, args); 1433 va_end(args); 1434 1435 /* Display the error locally */ 1436 logit("Disconnecting: %.100s", buf); 1437 1438 /* Send the disconnect message to the other side, and wait for it to get sent. */ 1439 if (compat20) { 1440 packet_start(SSH2_MSG_DISCONNECT); 1441 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); 1442 packet_put_cstring(buf); 1443 packet_put_cstring(""); 1444 } else { 1445 packet_start(SSH_MSG_DISCONNECT); 1446 packet_put_cstring(buf); 1447 } 1448 packet_send(); 1449 packet_write_wait(); 1450 1451 /* Stop listening for connections. */ 1452 channel_close_all(); 1453 1454 /* Close the connection. */ 1455 packet_close(); 1456 cleanup_exit(255); 1457 } 1458 1459 /* Checks if there is any buffered output, and tries to write some of the output. */ 1460 1461 void 1462 packet_write_poll(void) 1463 { 1464 int len = buffer_len(&output); 1465 1466 if (len > 0) { 1467 len = write(connection_out, buffer_ptr(&output), len); 1468 if (len <= 0) { 1469 if (errno == EAGAIN) 1470 return; 1471 else 1472 fatal("Write failed: %.100s", strerror(errno)); 1473 } 1474 buffer_consume(&output, len); 1475 } 1476 } 1477 1478 /* 1479 * Calls packet_write_poll repeatedly until all pending output data has been 1480 * written. 1481 */ 1482 1483 void 1484 packet_write_wait(void) 1485 { 1486 fd_set *setp; 1487 int ret, ms_remain; 1488 struct timeval start, timeout, *timeoutp = NULL; 1489 1490 setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS), 1491 sizeof(fd_mask)); 1492 packet_write_poll(); 1493 while (packet_have_data_to_write()) { 1494 memset(setp, 0, howmany(connection_out + 1, NFDBITS) * 1495 sizeof(fd_mask)); 1496 FD_SET(connection_out, setp); 1497 1498 if (packet_timeout_ms > 0) { 1499 ms_remain = packet_timeout_ms; 1500 timeoutp = &timeout; 1501 } 1502 for (;;) { 1503 if (packet_timeout_ms != -1) { 1504 ms_to_timeval(&timeout, ms_remain); 1505 gettimeofday(&start, NULL); 1506 } 1507 if ((ret = select(connection_out + 1, NULL, setp, 1508 NULL, timeoutp)) >= 0) 1509 break; 1510 if (errno != EAGAIN && errno != EINTR) 1511 break; 1512 if (packet_timeout_ms == -1) 1513 continue; 1514 ms_subtract_diff(&start, &ms_remain); 1515 if (ms_remain <= 0) { 1516 ret = 0; 1517 break; 1518 } 1519 } 1520 if (ret == 0) { 1521 logit("Connection to %.200s timed out while " 1522 "waiting to write", get_remote_ipaddr()); 1523 cleanup_exit(255); 1524 } 1525 packet_write_poll(); 1526 } 1527 xfree(setp); 1528 } 1529 1530 /* Returns true if there is buffered data to write to the connection. */ 1531 1532 int 1533 packet_have_data_to_write(void) 1534 { 1535 return buffer_len(&output) != 0; 1536 } 1537 1538 /* Returns true if there is not too much data to write to the connection. */ 1539 1540 int 1541 packet_not_very_much_data_to_write(void) 1542 { 1543 if (interactive_mode) 1544 return buffer_len(&output) < 16384; 1545 else 1546 return buffer_len(&output) < 128 * 1024; 1547 } 1548 1549 static void 1550 packet_set_tos(int interactive) 1551 { 1552 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; 1553 1554 if (!packet_connection_is_on_socket() || 1555 !packet_connection_is_ipv4()) 1556 return; 1557 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, 1558 sizeof(tos)) < 0) 1559 error("setsockopt IP_TOS %d: %.100s:", 1560 tos, strerror(errno)); 1561 } 1562 1563 /* Informs that the current session is interactive. Sets IP flags for that. */ 1564 1565 void 1566 packet_set_interactive(int interactive) 1567 { 1568 static int called = 0; 1569 1570 if (called) 1571 return; 1572 called = 1; 1573 1574 /* Record that we are in interactive mode. */ 1575 interactive_mode = interactive; 1576 1577 /* Only set socket options if using a socket. */ 1578 if (!packet_connection_is_on_socket()) 1579 return; 1580 set_nodelay(connection_in); 1581 packet_set_tos(interactive); 1582 } 1583 1584 /* Returns true if the current connection is interactive. */ 1585 1586 int 1587 packet_is_interactive(void) 1588 { 1589 return interactive_mode; 1590 } 1591 1592 int 1593 packet_set_maxsize(u_int s) 1594 { 1595 static int called = 0; 1596 1597 if (called) { 1598 logit("packet_set_maxsize: called twice: old %d new %d", 1599 max_packet_size, s); 1600 return -1; 1601 } 1602 if (s < 4 * 1024 || s > 1024 * 1024) { 1603 logit("packet_set_maxsize: bad size %d", s); 1604 return -1; 1605 } 1606 called = 1; 1607 debug("packet_set_maxsize: setting to %d", s); 1608 max_packet_size = s; 1609 return s; 1610 } 1611 1612 /* roundup current message to pad bytes */ 1613 void 1614 packet_add_padding(u_char pad) 1615 { 1616 extra_pad = pad; 1617 } 1618 1619 /* 1620 * 9.2. Ignored Data Message 1621 * 1622 * byte SSH_MSG_IGNORE 1623 * string data 1624 * 1625 * All implementations MUST understand (and ignore) this message at any 1626 * time (after receiving the protocol version). No implementation is 1627 * required to send them. This message can be used as an additional 1628 * protection measure against advanced traffic analysis techniques. 1629 */ 1630 void 1631 packet_send_ignore(int nbytes) 1632 { 1633 u_int32_t rnd = 0; 1634 int i; 1635 1636 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); 1637 packet_put_int(nbytes); 1638 for (i = 0; i < nbytes; i++) { 1639 if (i % 4 == 0) 1640 rnd = arc4random(); 1641 packet_put_char((u_char)rnd & 0xff); 1642 rnd >>= 8; 1643 } 1644 } 1645 1646 #define MAX_PACKETS (1U<<31) 1647 int 1648 packet_need_rekeying(void) 1649 { 1650 if (datafellows & SSH_BUG_NOREKEY) 1651 return 0; 1652 return 1653 (p_send.packets > MAX_PACKETS) || 1654 (p_read.packets > MAX_PACKETS) || 1655 (max_blocks_out && (p_send.blocks > max_blocks_out)) || 1656 (max_blocks_in && (p_read.blocks > max_blocks_in)); 1657 } 1658 1659 void 1660 packet_set_rekey_limit(u_int32_t bytes) 1661 { 1662 rekey_limit = bytes; 1663 } 1664 1665 void 1666 packet_set_server(void) 1667 { 1668 server_side = 1; 1669 } 1670 1671 void 1672 packet_set_authenticated(void) 1673 { 1674 after_authentication = 1; 1675 } 1676