crypto/openssh/packet.c

   1 /* $OpenBSD: packet.c,v 1.173 2011/05/06 21:14:05 djm Exp $ */
   2 /* $FreeBSD$ */
   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
  43 #include <sys/types.h>
  44 #include "openbsd-compat/sys-queue.h"
  45 #include <sys/param.h>
  46 #include <sys/socket.h>
  47 #ifdef HAVE_SYS_TIME_H
  48 # include <sys/time.h>
  49 #endif
  50
  51 #include <netinet/in.h>
  52 #include <netinet/ip.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <stdarg.h>
  57 #include <stdio.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <unistd.h>
  61 #include <signal.h>
  62
  63 #include "xmalloc.h"
  64 #include "buffer.h"
  65 #include "packet.h"
  66 #include "crc32.h"
  67 #include "compress.h"
  68 #include "deattack.h"
  69 #include "channels.h"
  70 #include "compat.h"
  71 #include "ssh1.h"
  72 #include "ssh2.h"
  73 #include "cipher.h"
  74 #include "key.h"
  75 #include "kex.h"
  76 #include "mac.h"
  77 #include "log.h"
  78 #include "canohost.h"
  79 #include "misc.h"
  80 #include "ssh.h"
  81 #include "roaming.h"
  82
  83 #ifdef PACKET_DEBUG
  84 #define DBG(x) x
  85 #else
  86 #define DBG(x)
  87 #endif
  88
  89 #define PACKET_MAX_SIZE (256 * 1024)
  90
  91 struct packet_state {
  92         u_int32_t seqnr;
  93         u_int32_t packets;
  94         u_int64_t blocks;
  95         u_int64_t bytes;
  96 };
  97
  98 struct packet {
  99         TAILQ_ENTRY(packet) next;
 100         u_char type;
 101         Buffer payload;
 102 };
 103
 104 struct session_state {
 105         /*
 106          * This variable contains the file descriptors used for
 107          * communicating with the other side.  connection_in is used for
 108          * reading; connection_out for writing.  These can be the same
 109          * descriptor, in which case it is assumed to be a socket.
 110          */
 111         int connection_in;
 112         int connection_out;
 113
 114         /* Protocol flags for the remote side. */
 115         u_int remote_protocol_flags;
 116
 117         /* Encryption context for receiving data.  Only used for decryption. */
 118         CipherContext receive_context;
 119
 120         /* Encryption context for sending data.  Only used for encryption. */
 121         CipherContext send_context;
 122
 123         /* Buffer for raw input data from the socket. */
 124         Buffer input;
 125
 126         /* Buffer for raw output data going to the socket. */
 127         Buffer output;
 128
 129         /* Buffer for the partial outgoing packet being constructed. */
 130         Buffer outgoing_packet;
 131
 132         /* Buffer for the incoming packet currently being processed. */
 133         Buffer incoming_packet;
 134
 135         /* Scratch buffer for packet compression/decompression. */
 136         Buffer compression_buffer;
 137         int compression_buffer_ready;
 138
 139         /*
 140          * Flag indicating whether packet compression/decompression is
 141          * enabled.
 142          */
 143         int packet_compression;
 144
 145         /* default maximum packet size */
 146         u_int max_packet_size;
 147
 148         /* Flag indicating whether this module has been initialized. */
 149         int initialized;
 150
 151         /* Set to true if the connection is interactive. */
 152         int interactive_mode;
 153
 154         /* Set to true if we are the server side. */
 155         int server_side;
 156
 157         /* Set to true if we are authenticated. */
 158         int after_authentication;
 159
 160         int keep_alive_timeouts;
 161
 162         /* The maximum time that we will wait to send or receive a packet */
 163         int packet_timeout_ms;
 164
 165         /* Session key information for Encryption and MAC */
 166         Newkeys *newkeys[MODE_MAX];
 167         struct packet_state p_read, p_send;
 168
 169         u_int64_t max_blocks_in, max_blocks_out;
 170         u_int32_t rekey_limit;
 171
 172         /* Session key for protocol v1 */
 173         u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
 174         u_int ssh1_keylen;
 175
 176         /* roundup current message to extra_pad bytes */
 177         u_char extra_pad;
 178
 179         /* XXX discard incoming data after MAC error */
 180         u_int packet_discard;
 181         Mac *packet_discard_mac;
 182
 183         /* Used in packet_read_poll2() */
 184         u_int packlen;
 185
 186         /* Used in packet_send2 */
 187         int rekeying;
 188
 189         /* Used in packet_set_interactive */
 190         int set_interactive_called;
 191
 192         /* Used in packet_set_maxsize */
 193         int set_maxsize_called;
 194
 195         TAILQ_HEAD(, packet) outgoing;
 196 };
 197
 198 static struct session_state *active_state, *backup_state;
 199 #ifdef  NONE_CIPHER_ENABLED
 200 static int rekey_requested = 0;
 201 #endif
 202
 203 static struct session_state *
 204 alloc_session_state(void)
 205 {
 206         struct session_state *s = xcalloc(1, sizeof(*s));
 207
 208         s->connection_in = -1;
 209         s->connection_out = -1;
 210         s->max_packet_size = 32768;
 211         s->packet_timeout_ms = -1;
 212         return s;
 213 }
 214
 215 /*
 216  * Sets the descriptors used for communication.  Disables encryption until
 217  * packet_set_encryption_key is called.
 218  */
 219 void
 220 packet_set_connection(int fd_in, int fd_out)
 221 {
 222         Cipher *none = cipher_by_name("none");
 223
 224         if (none == NULL)
 225                 fatal("packet_set_connection: cannot load cipher 'none'");
 226         if (active_state == NULL)
 227                 active_state = alloc_session_state();
 228         active_state->connection_in = fd_in;
 229         active_state->connection_out = fd_out;
 230         cipher_init(&active_state->send_context, none, (const u_char *)"",
 231             0, NULL, 0, CIPHER_ENCRYPT);
 232         cipher_init(&active_state->receive_context, none, (const u_char *)"",
 233             0, NULL, 0, CIPHER_DECRYPT);
 234         active_state->newkeys[MODE_IN] = active_state->newkeys[MODE_OUT] = NULL;
 235         if (!active_state->initialized) {
 236                 active_state->initialized = 1;
 237                 buffer_init(&active_state->input);
 238                 buffer_init(&active_state->output);
 239                 buffer_init(&active_state->outgoing_packet);
 240                 buffer_init(&active_state->incoming_packet);
 241                 TAILQ_INIT(&active_state->outgoing);
 242                 active_state->p_send.packets = active_state->p_read.packets = 0;
 243         }
 244 }
 245
 246 void
 247 packet_set_timeout(int timeout, int count)
 248 {
 249         if (timeout == 0 || count == 0) {
 250                 active_state->packet_timeout_ms = -1;
 251                 return;
 252         }
 253         if ((INT_MAX / 1000) / count < timeout)
 254                 active_state->packet_timeout_ms = INT_MAX;
 255         else
 256                 active_state->packet_timeout_ms = timeout * count * 1000;
 257 }
 258
 259 static void
 260 packet_stop_discard(void)
 261 {
 262         if (active_state->packet_discard_mac) {
 263                 char buf[1024];
 264
 265                 memset(buf, 'a', sizeof(buf));
 266                 while (buffer_len(&active_state->incoming_packet) <
 267                     PACKET_MAX_SIZE)
 268                         buffer_append(&active_state->incoming_packet, buf,
 269                             sizeof(buf));
 270                 (void) mac_compute(active_state->packet_discard_mac,
 271                     active_state->p_read.seqnr,
 272                     buffer_ptr(&active_state->incoming_packet),
 273                     PACKET_MAX_SIZE);
 274         }
 275         logit("Finished discarding for %.200s", get_remote_ipaddr());
 276         cleanup_exit(255);
 277 }
 278
 279 static void
 280 packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard)
 281 {
 282         if (enc == NULL || !cipher_is_cbc(enc->cipher))
 283                 packet_disconnect("Packet corrupt");
 284         if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
 285                 active_state->packet_discard_mac = mac;
 286         if (buffer_len(&active_state->input) >= discard)
 287                 packet_stop_discard();
 288         active_state->packet_discard = discard -
 289             buffer_len(&active_state->input);
 290 }
 291
 292 /* Returns 1 if remote host is connected via socket, 0 if not. */
 293
 294 int
 295 packet_connection_is_on_socket(void)
 296 {
 297         struct sockaddr_storage from, to;
 298         socklen_t fromlen, tolen;
 299
 300         /* filedescriptors in and out are the same, so it's a socket */
 301         if (active_state->connection_in == active_state->connection_out)
 302                 return 1;
 303         fromlen = sizeof(from);
 304         memset(&from, 0, sizeof(from));
 305         if (getpeername(active_state->connection_in, (struct sockaddr *)&from,
 306             &fromlen) < 0)
 307                 return 0;
 308         tolen = sizeof(to);
 309         memset(&to, 0, sizeof(to));
 310         if (getpeername(active_state->connection_out, (struct sockaddr *)&to,
 311             &tolen) < 0)
 312                 return 0;
 313         if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
 314                 return 0;
 315         if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
 316                 return 0;
 317         return 1;
 318 }
 319
 320 /*
 321  * Exports an IV from the CipherContext required to export the key
 322  * state back from the unprivileged child to the privileged parent
 323  * process.
 324  */
 325
 326 void
 327 packet_get_keyiv(int mode, u_char *iv, u_int len)
 328 {
 329         CipherContext *cc;
 330
 331         if (mode == MODE_OUT)
 332                 cc = &active_state->send_context;
 333         else
 334                 cc = &active_state->receive_context;
 335
 336         cipher_get_keyiv(cc, iv, len);
 337 }
 338
 339 int
 340 packet_get_keycontext(int mode, u_char *dat)
 341 {
 342         CipherContext *cc;
 343
 344         if (mode == MODE_OUT)
 345                 cc = &active_state->send_context;
 346         else
 347                 cc = &active_state->receive_context;
 348
 349         return (cipher_get_keycontext(cc, dat));
 350 }
 351
 352 void
 353 packet_set_keycontext(int mode, u_char *dat)
 354 {
 355         CipherContext *cc;
 356
 357         if (mode == MODE_OUT)
 358                 cc = &active_state->send_context;
 359         else
 360                 cc = &active_state->receive_context;
 361
 362         cipher_set_keycontext(cc, dat);
 363 }
 364
 365 int
 366 packet_get_keyiv_len(int mode)
 367 {
 368         CipherContext *cc;
 369
 370         if (mode == MODE_OUT)
 371                 cc = &active_state->send_context;
 372         else
 373                 cc = &active_state->receive_context;
 374
 375         return (cipher_get_keyiv_len(cc));
 376 }
 377
 378 void
 379 packet_set_iv(int mode, u_char *dat)
 380 {
 381         CipherContext *cc;
 382
 383         if (mode == MODE_OUT)
 384                 cc = &active_state->send_context;
 385         else
 386                 cc = &active_state->receive_context;
 387
 388         cipher_set_keyiv(cc, dat);
 389 }
 390
 391 int
 392 packet_get_ssh1_cipher(void)
 393 {
 394         return (cipher_get_number(active_state->receive_context.cipher));
 395 }
 396
 397 void
 398 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks,
 399     u_int32_t *packets, u_int64_t *bytes)
 400 {
 401         struct packet_state *state;
 402
 403         state = (mode == MODE_IN) ?
 404             &active_state->p_read : &active_state->p_send;
 405         if (seqnr)
 406                 *seqnr = state->seqnr;
 407         if (blocks)
 408                 *blocks = state->blocks;
 409         if (packets)
 410                 *packets = state->packets;
 411         if (bytes)
 412                 *bytes = state->bytes;
 413 }
 414
 415 void
 416 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
 417     u_int64_t bytes)
 418 {
 419         struct packet_state *state;
 420
 421         state = (mode == MODE_IN) ?
 422             &active_state->p_read : &active_state->p_send;
 423         state->seqnr = seqnr;
 424         state->blocks = blocks;
 425         state->packets = packets;
 426         state->bytes = bytes;
 427 }
 428
 429 static int
 430 packet_connection_af(void)
 431 {
 432         struct sockaddr_storage to;
 433         socklen_t tolen = sizeof(to);
 434
 435         memset(&to, 0, sizeof(to));
 436         if (getsockname(active_state->connection_out, (struct sockaddr *)&to,
 437             &tolen) < 0)
 438                 return 0;
 439         if (to.ss_family == AF_INET)
 440                 return 1;
 441 #ifdef IPV4_IN_IPV6
 442         if (to.ss_family == AF_INET6 &&
 443             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
 444                 return AF_INET;
 445 #endif
 446         return to.ss_family;
 447 }
 448
 449 /* Sets the connection into non-blocking mode. */
 450
 451 void
 452 packet_set_nonblocking(void)
 453 {
 454         /* Set the socket into non-blocking mode. */
 455         set_nonblock(active_state->connection_in);
 456
 457         if (active_state->connection_out != active_state->connection_in)
 458                 set_nonblock(active_state->connection_out);
 459 }
 460
 461 /* Returns the socket used for reading. */
 462
 463 int
 464 packet_get_connection_in(void)
 465 {
 466         return active_state->connection_in;
 467 }
 468
 469 /* Returns the descriptor used for writing. */
 470
 471 int
 472 packet_get_connection_out(void)
 473 {
 474         return active_state->connection_out;
 475 }
 476
 477 /* Closes the connection and clears and frees internal data structures. */
 478
 479 void
 480 packet_close(void)
 481 {
 482         if (!active_state->initialized)
 483                 return;
 484         active_state->initialized = 0;
 485         if (active_state->connection_in == active_state->connection_out) {
 486                 shutdown(active_state->connection_out, SHUT_RDWR);
 487                 close(active_state->connection_out);
 488         } else {
 489                 close(active_state->connection_in);
 490                 close(active_state->connection_out);
 491         }
 492         buffer_free(&active_state->input);
 493         buffer_free(&active_state->output);
 494         buffer_free(&active_state->outgoing_packet);
 495         buffer_free(&active_state->incoming_packet);
 496         if (active_state->compression_buffer_ready) {
 497                 buffer_free(&active_state->compression_buffer);
 498                 buffer_compress_uninit();
 499         }
 500         cipher_cleanup(&active_state->send_context);
 501         cipher_cleanup(&active_state->receive_context);
 502 }
 503
 504 /* Sets remote side protocol flags. */
 505
 506 void
 507 packet_set_protocol_flags(u_int protocol_flags)
 508 {
 509         active_state->remote_protocol_flags = protocol_flags;
 510 }
 511
 512 /* Returns the remote protocol flags set earlier by the above function. */
 513
 514 u_int
 515 packet_get_protocol_flags(void)
 516 {
 517         return active_state->remote_protocol_flags;
 518 }
 519
 520 /*
 521  * Starts packet compression from the next packet on in both directions.
 522  * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
 523  */
 524
 525 static void
 526 packet_init_compression(void)
 527 {
 528         if (active_state->compression_buffer_ready == 1)
 529                 return;
 530         active_state->compression_buffer_ready = 1;
 531         buffer_init(&active_state->compression_buffer);
 532 }
 533
 534 void
 535 packet_start_compression(int level)
 536 {
 537         if (active_state->packet_compression && !compat20)
 538                 fatal("Compression already enabled.");
 539         active_state->packet_compression = 1;
 540         packet_init_compression();
 541         buffer_compress_init_send(level);
 542         buffer_compress_init_recv();
 543 }
 544
 545 /*
 546  * Causes any further packets to be encrypted using the given key.  The same
 547  * key is used for both sending and reception.  However, both directions are
 548  * encrypted independently of each other.
 549  */
 550
 551 void
 552 packet_set_encryption_key(const u_char *key, u_int keylen, int number)
 553 {
 554         Cipher *cipher = cipher_by_number(number);
 555
 556         if (cipher == NULL)
 557                 fatal("packet_set_encryption_key: unknown cipher number %d", number);
 558         if (keylen < 20)
 559                 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
 560         if (keylen > SSH_SESSION_KEY_LENGTH)
 561                 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
 562         memcpy(active_state->ssh1_key, key, keylen);
 563         active_state->ssh1_keylen = keylen;
 564         cipher_init(&active_state->send_context, cipher, key, keylen, NULL,
 565             0, CIPHER_ENCRYPT);
 566         cipher_init(&active_state->receive_context, cipher, key, keylen, NULL,
 567             0, CIPHER_DECRYPT);
 568 }
 569
 570 u_int
 571 packet_get_encryption_key(u_char *key)
 572 {
 573         if (key == NULL)
 574                 return (active_state->ssh1_keylen);
 575         memcpy(key, active_state->ssh1_key, active_state->ssh1_keylen);
 576         return (active_state->ssh1_keylen);
 577 }
 578
 579 /* Start constructing a packet to send. */
 580 void
 581 packet_start(u_char type)
 582 {
 583         u_char buf[9];
 584         int len;
 585
 586         DBG(debug("packet_start[%d]", type));
 587         len = compat20 ? 6 : 9;
 588         memset(buf, 0, len - 1);
 589         buf[len - 1] = type;
 590         buffer_clear(&active_state->outgoing_packet);
 591         buffer_append(&active_state->outgoing_packet, buf, len);
 592 }
 593
 594 /* Append payload. */
 595 void
 596 packet_put_char(int value)
 597 {
 598         char ch = value;
 599
 600         buffer_append(&active_state->outgoing_packet, &ch, 1);
 601 }
 602
 603 void
 604 packet_put_int(u_int value)
 605 {
 606         buffer_put_int(&active_state->outgoing_packet, value);
 607 }
 608
 609 void
 610 packet_put_int64(u_int64_t value)
 611 {
 612         buffer_put_int64(&active_state->outgoing_packet, value);
 613 }
 614
 615 void
 616 packet_put_string(const void *buf, u_int len)
 617 {
 618         buffer_put_string(&active_state->outgoing_packet, buf, len);
 619 }
 620
 621 void
 622 packet_put_cstring(const char *str)
 623 {
 624         buffer_put_cstring(&active_state->outgoing_packet, str);
 625 }
 626
 627 void
 628 packet_put_raw(const void *buf, u_int len)
 629 {
 630         buffer_append(&active_state->outgoing_packet, buf, len);
 631 }
 632
 633 void
 634 packet_put_bignum(BIGNUM * value)
 635 {
 636         buffer_put_bignum(&active_state->outgoing_packet, value);
 637 }
 638
 639 void
 640 packet_put_bignum2(BIGNUM * value)
 641 {
 642         buffer_put_bignum2(&active_state->outgoing_packet, value);
 643 }
 644
 645 #ifdef OPENSSL_HAS_ECC
 646 void
 647 packet_put_ecpoint(const EC_GROUP *curve, const EC_POINT *point)
 648 {
 649         buffer_put_ecpoint(&active_state->outgoing_packet, curve, point);
 650 }
 651 #endif
 652
 653 /*
 654  * Finalizes and sends the packet.  If the encryption key has been set,
 655  * encrypts the packet before sending.
 656  */
 657
 658 static void
 659 packet_send1(void)
 660 {
 661         u_char buf[8], *cp;
 662         int i, padding, len;
 663         u_int checksum;
 664         u_int32_t rnd = 0;
 665
 666         /*
 667          * If using packet compression, compress the payload of the outgoing
 668          * packet.
 669          */
 670         if (active_state->packet_compression) {
 671                 buffer_clear(&active_state->compression_buffer);
 672                 /* Skip padding. */
 673                 buffer_consume(&active_state->outgoing_packet, 8);
 674                 /* padding */
 675                 buffer_append(&active_state->compression_buffer,
 676                     "\0\0\0\0\0\0\0\0", 8);
 677                 buffer_compress(&active_state->outgoing_packet,
 678                     &active_state->compression_buffer);
 679                 buffer_clear(&active_state->outgoing_packet);
 680                 buffer_append(&active_state->outgoing_packet,
 681                     buffer_ptr(&active_state->compression_buffer),
 682                     buffer_len(&active_state->compression_buffer));
 683         }
 684         /* Compute packet length without padding (add checksum, remove padding). */
 685         len = buffer_len(&active_state->outgoing_packet) + 4 - 8;
 686
 687         /* Insert padding. Initialized to zero in packet_start1() */
 688         padding = 8 - len % 8;
 689         if (!active_state->send_context.plaintext) {
 690                 cp = buffer_ptr(&active_state->outgoing_packet);
 691                 for (i = 0; i < padding; i++) {
 692                         if (i % 4 == 0)
 693                                 rnd = arc4random();
 694                         cp[7 - i] = rnd & 0xff;
 695                         rnd >>= 8;
 696                 }
 697         }
 698         buffer_consume(&active_state->outgoing_packet, 8 - padding);
 699
 700         /* Add check bytes. */
 701         checksum = ssh_crc32(buffer_ptr(&active_state->outgoing_packet),
 702             buffer_len(&active_state->outgoing_packet));
 703         put_u32(buf, checksum);
 704         buffer_append(&active_state->outgoing_packet, buf, 4);
 705
 706 #ifdef PACKET_DEBUG
 707         fprintf(stderr, "packet_send plain: ");
 708         buffer_dump(&active_state->outgoing_packet);
 709 #endif
 710
 711         /* Append to output. */
 712         put_u32(buf, len);
 713         buffer_append(&active_state->output, buf, 4);
 714         cp = buffer_append_space(&active_state->output,
 715             buffer_len(&active_state->outgoing_packet));
 716         cipher_crypt(&active_state->send_context, cp,
 717             buffer_ptr(&active_state->outgoing_packet),
 718             buffer_len(&active_state->outgoing_packet));
 719
 720 #ifdef PACKET_DEBUG
 721         fprintf(stderr, "encrypted: ");
 722         buffer_dump(&active_state->output);
 723 #endif
 724         active_state->p_send.packets++;
 725         active_state->p_send.bytes += len +
 726             buffer_len(&active_state->outgoing_packet);
 727         buffer_clear(&active_state->outgoing_packet);
 728
 729         /*
 730          * Note that the packet is now only buffered in output.  It won't be
 731          * actually sent until packet_write_wait or packet_write_poll is
 732          * called.
 733          */
 734 }
 735
 736 void
 737 set_newkeys(int mode)
 738 {
 739         Enc *enc;
 740         Mac *mac;
 741         Comp *comp;
 742         CipherContext *cc;
 743         u_int64_t *max_blocks;
 744         int crypt_type;
 745
 746         debug2("set_newkeys: mode %d", mode);
 747
 748         if (mode == MODE_OUT) {
 749                 cc = &active_state->send_context;
 750                 crypt_type = CIPHER_ENCRYPT;
 751                 active_state->p_send.packets = active_state->p_send.blocks = 0;
 752                 max_blocks = &active_state->max_blocks_out;
 753         } else {
 754                 cc = &active_state->receive_context;
 755                 crypt_type = CIPHER_DECRYPT;
 756                 active_state->p_read.packets = active_state->p_read.blocks = 0;
 757                 max_blocks = &active_state->max_blocks_in;
 758         }
 759         if (active_state->newkeys[mode] != NULL) {
 760                 debug("set_newkeys: rekeying");
 761                 cipher_cleanup(cc);
 762                 enc  = &active_state->newkeys[mode]->enc;
 763                 mac  = &active_state->newkeys[mode]->mac;
 764                 comp = &active_state->newkeys[mode]->comp;
 765                 mac_clear(mac);
 766                 xfree(enc->name);
 767                 xfree(enc->iv);
 768                 xfree(enc->key);
 769                 xfree(mac->name);
 770                 xfree(mac->key);
 771                 xfree(comp->name);
 772                 xfree(active_state->newkeys[mode]);
 773         }
 774         active_state->newkeys[mode] = kex_get_newkeys(mode);
 775         if (active_state->newkeys[mode] == NULL)
 776                 fatal("newkeys: no keys for mode %d", mode);
 777         enc  = &active_state->newkeys[mode]->enc;
 778         mac  = &active_state->newkeys[mode]->mac;
 779         comp = &active_state->newkeys[mode]->comp;
 780         if (mac_init(mac) == 0)
 781                 mac->enabled = 1;
 782         DBG(debug("cipher_init_context: %d", mode));
 783         cipher_init(cc, enc->cipher, enc->key, enc->key_len,
 784             enc->iv, enc->block_size, crypt_type);
 785         /* Deleting the keys does not gain extra security */
 786         /* memset(enc->iv,  0, enc->block_size);
 787            memset(enc->key, 0, enc->key_len);
 788            memset(mac->key, 0, mac->key_len); */
 789         if ((comp->type == COMP_ZLIB ||
 790             (comp->type == COMP_DELAYED &&
 791              active_state->after_authentication)) && comp->enabled == 0) {
 792                 packet_init_compression();
 793                 if (mode == MODE_OUT)
 794                         buffer_compress_init_send(6);
 795                 else
 796                         buffer_compress_init_recv();
 797                 comp->enabled = 1;
 798         }
 799         /*
 800          * The 2^(blocksize*2) limit is too expensive for 3DES,
 801          * blowfish, etc, so enforce a 1GB limit for small blocksizes.
 802          */
 803         if (enc->block_size >= 16)
 804                 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
 805         else
 806                 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
 807         if (active_state->rekey_limit)
 808                 *max_blocks = MIN(*max_blocks,
 809                     active_state->rekey_limit / enc->block_size);
 810 }
 811
 812 /*
 813  * Delayed compression for SSH2 is enabled after authentication:
 814  * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
 815  * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
 816  */
 817 static void
 818 packet_enable_delayed_compress(void)
 819 {
 820         Comp *comp = NULL;
 821         int mode;
 822
 823         /*
 824          * Remember that we are past the authentication step, so rekeying
 825          * with COMP_DELAYED will turn on compression immediately.
 826          */
 827         active_state->after_authentication = 1;
 828         for (mode = 0; mode < MODE_MAX; mode++) {
 829                 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
 830                 if (active_state->newkeys[mode] == NULL)
 831                         continue;
 832                 comp = &active_state->newkeys[mode]->comp;
 833                 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
 834                         packet_init_compression();
 835                         if (mode == MODE_OUT)
 836                                 buffer_compress_init_send(6);
 837                         else
 838                                 buffer_compress_init_recv();
 839                         comp->enabled = 1;
 840                 }
 841         }
 842 }
 843
 844 /*
 845  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
 846  */
 847 static void
 848 packet_send2_wrapped(void)
 849 {
 850         u_char type, *cp, *macbuf = NULL;
 851         u_char padlen, pad;
 852         u_int packet_length = 0;
 853         u_int i, len;
 854         u_int32_t rnd = 0;
 855         Enc *enc   = NULL;
 856         Mac *mac   = NULL;
 857         Comp *comp = NULL;
 858         int block_size;
 859
 860         if (active_state->newkeys[MODE_OUT] != NULL) {
 861                 enc  = &active_state->newkeys[MODE_OUT]->enc;
 862                 mac  = &active_state->newkeys[MODE_OUT]->mac;
 863                 comp = &active_state->newkeys[MODE_OUT]->comp;
 864         }
 865         block_size = enc ? enc->block_size : 8;
 866
 867         cp = buffer_ptr(&active_state->outgoing_packet);
 868         type = cp[5];
 869
 870 #ifdef PACKET_DEBUG
 871         fprintf(stderr, "plain:     ");
 872         buffer_dump(&active_state->outgoing_packet);
 873 #endif
 874
 875         if (comp && comp->enabled) {
 876                 len = buffer_len(&active_state->outgoing_packet);
 877                 /* skip header, compress only payload */
 878                 buffer_consume(&active_state->outgoing_packet, 5);
 879                 buffer_clear(&active_state->compression_buffer);
 880                 buffer_compress(&active_state->outgoing_packet,
 881                     &active_state->compression_buffer);
 882                 buffer_clear(&active_state->outgoing_packet);
 883                 buffer_append(&active_state->outgoing_packet, "\0\0\0\0\0", 5);
 884                 buffer_append(&active_state->outgoing_packet,
 885                     buffer_ptr(&active_state->compression_buffer),
 886                     buffer_len(&active_state->compression_buffer));
 887                 DBG(debug("compression: raw %d compressed %d", len,
 888                     buffer_len(&active_state->outgoing_packet)));
 889         }
 890
 891         /* sizeof (packet_len + pad_len + payload) */
 892         len = buffer_len(&active_state->outgoing_packet);
 893
 894         /*
 895          * calc size of padding, alloc space, get random data,
 896          * minimum padding is 4 bytes
 897          */
 898         padlen = block_size - (len % block_size);
 899         if (padlen < 4)
 900                 padlen += block_size;
 901         if (active_state->extra_pad) {
 902                 /* will wrap if extra_pad+padlen > 255 */
 903                 active_state->extra_pad =
 904                     roundup(active_state->extra_pad, block_size);
 905                 pad = active_state->extra_pad -
 906                     ((len + padlen) % active_state->extra_pad);
 907                 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
 908                     pad, len, padlen, active_state->extra_pad);
 909                 padlen += pad;
 910                 active_state->extra_pad = 0;
 911         }
 912         cp = buffer_append_space(&active_state->outgoing_packet, padlen);
 913         if (enc && !active_state->send_context.plaintext) {
 914                 /* random padding */
 915                 for (i = 0; i < padlen; i++) {
 916                         if (i % 4 == 0)
 917                                 rnd = arc4random();
 918                         cp[i] = rnd & 0xff;
 919                         rnd >>= 8;
 920                 }
 921         } else {
 922                 /* clear padding */
 923                 memset(cp, 0, padlen);
 924         }
 925         /* packet_length includes payload, padding and padding length field */
 926         packet_length = buffer_len(&active_state->outgoing_packet) - 4;
 927         cp = buffer_ptr(&active_state->outgoing_packet);
 928         put_u32(cp, packet_length);
 929         cp[4] = padlen;
 930         DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
 931
 932         /* compute MAC over seqnr and packet(length fields, payload, padding) */
 933         if (mac && mac->enabled) {
 934                 macbuf = mac_compute(mac, active_state->p_send.seqnr,
 935                     buffer_ptr(&active_state->outgoing_packet),
 936                     buffer_len(&active_state->outgoing_packet));
 937                 DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
 938         }
 939         /* encrypt packet and append to output buffer. */
 940         cp = buffer_append_space(&active_state->output,
 941             buffer_len(&active_state->outgoing_packet));
 942         cipher_crypt(&active_state->send_context, cp,
 943             buffer_ptr(&active_state->outgoing_packet),
 944             buffer_len(&active_state->outgoing_packet));
 945         /* append unencrypted MAC */
 946         if (mac && mac->enabled)
 947                 buffer_append(&active_state->output, macbuf, mac->mac_len);
 948 #ifdef PACKET_DEBUG
 949         fprintf(stderr, "encrypted: ");
 950         buffer_dump(&active_state->output);
 951 #endif
 952         /* increment sequence number for outgoing packets */
 953         if (++active_state->p_send.seqnr == 0)
 954                 logit("outgoing seqnr wraps around");
 955         if (++active_state->p_send.packets == 0)
 956                 if (!(datafellows & SSH_BUG_NOREKEY))
 957                         fatal("XXX too many packets with same key");
 958         active_state->p_send.blocks += (packet_length + 4) / block_size;
 959         active_state->p_send.bytes += packet_length + 4;
 960         buffer_clear(&active_state->outgoing_packet);
 961
 962         if (type == SSH2_MSG_NEWKEYS)
 963                 set_newkeys(MODE_OUT);
 964         else if (type == SSH2_MSG_USERAUTH_SUCCESS && active_state->server_side)
 965                 packet_enable_delayed_compress();
 966 }
 967
 968 static void
 969 packet_send2(void)
 970 {
 971         struct packet *p;
 972         u_char type, *cp;
 973
 974         cp = buffer_ptr(&active_state->outgoing_packet);
 975         type = cp[5];
 976
 977         /* during rekeying we can only send key exchange messages */
 978         if (active_state->rekeying) {
 979                 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
 980                     (type <= SSH2_MSG_TRANSPORT_MAX))) {
 981                         debug("enqueue packet: %u", type);
 982                         p = xmalloc(sizeof(*p));
 983                         p->type = type;
 984                         memcpy(&p->payload, &active_state->outgoing_packet,
 985                             sizeof(Buffer));
 986                         buffer_init(&active_state->outgoing_packet);
 987                         TAILQ_INSERT_TAIL(&active_state->outgoing, p, next);
 988                         return;
 989                 }
 990         }
 991
 992         /* rekeying starts with sending KEXINIT */
 993         if (type == SSH2_MSG_KEXINIT)
 994                 active_state->rekeying = 1;
 995
 996         packet_send2_wrapped();
 997
 998         /* after a NEWKEYS message we can send the complete queue */
 999         if (type == SSH2_MSG_NEWKEYS) {
1000                 active_state->rekeying = 0;
1001                 while ((p = TAILQ_FIRST(&active_state->outgoing))) {
1002                         type = p->type;
1003                         debug("dequeue packet: %u", type);
1004                         buffer_free(&active_state->outgoing_packet);
1005                         memcpy(&active_state->outgoing_packet, &p->payload,
1006                             sizeof(Buffer));
1007                         TAILQ_REMOVE(&active_state->outgoing, p, next);
1008                         xfree(p);
1009                         packet_send2_wrapped();
1010                 }
1011         }
1012 }
1013
1014 void
1015 packet_send(void)
1016 {
1017         if (compat20)
1018                 packet_send2();
1019         else
1020                 packet_send1();
1021         DBG(debug("packet_send done"));
1022 }
1023
1024 /*
1025  * Waits until a packet has been received, and returns its type.  Note that
1026  * no other data is processed until this returns, so this function should not
1027  * be used during the interactive session.
1028  */
1029
1030 int
1031 packet_read_seqnr(u_int32_t *seqnr_p)
1032 {
1033         int type, len, ret, ms_remain, cont;
1034         fd_set *setp;
1035         char buf[8192];
1036         struct timeval timeout, start, *timeoutp = NULL;
1037
1038         DBG(debug("packet_read()"));
1039
1040         setp = (fd_set *)xcalloc(howmany(active_state->connection_in + 1,
1041             NFDBITS), sizeof(fd_mask));
1042
1043         /* Since we are blocking, ensure that all written packets have been sent. */
1044         packet_write_wait();
1045
1046         /* Stay in the loop until we have received a complete packet. */
1047         for (;;) {
1048                 /* Try to read a packet from the buffer. */
1049                 type = packet_read_poll_seqnr(seqnr_p);
1050                 if (!compat20 && (
1051                     type == SSH_SMSG_SUCCESS
1052                     || type == SSH_SMSG_FAILURE
1053                     || type == SSH_CMSG_EOF
1054                     || type == SSH_CMSG_EXIT_CONFIRMATION))
1055                         packet_check_eom();
1056                 /* If we got a packet, return it. */
1057                 if (type != SSH_MSG_NONE) {
1058                         xfree(setp);
1059                         return type;
1060                 }
1061                 /*
1062                  * Otherwise, wait for some data to arrive, add it to the
1063                  * buffer, and try again.
1064                  */
1065                 memset(setp, 0, howmany(active_state->connection_in + 1,
1066                     NFDBITS) * sizeof(fd_mask));
1067                 FD_SET(active_state->connection_in, setp);
1068
1069                 if (active_state->packet_timeout_ms > 0) {
1070                         ms_remain = active_state->packet_timeout_ms;
1071                         timeoutp = &timeout;
1072                 }
1073                 /* Wait for some data to arrive. */
1074                 for (;;) {
1075                         if (active_state->packet_timeout_ms != -1) {
1076                                 ms_to_timeval(&timeout, ms_remain);
1077                                 gettimeofday(&start, NULL);
1078                         }
1079                         if ((ret = select(active_state->connection_in + 1, setp,
1080                             NULL, NULL, timeoutp)) >= 0)
1081                                 break;
1082                         if (errno != EAGAIN && errno != EINTR &&
1083                             errno != EWOULDBLOCK)
1084                                 break;
1085                         if (active_state->packet_timeout_ms == -1)
1086                                 continue;
1087                         ms_subtract_diff(&start, &ms_remain);
1088                         if (ms_remain <= 0) {
1089                                 ret = 0;
1090                                 break;
1091                         }
1092                 }
1093                 if (ret == 0) {
1094                         logit("Connection to %.200s timed out while "
1095                             "waiting to read", get_remote_ipaddr());
1096                         cleanup_exit(255);
1097                 }
1098                 /* Read data from the socket. */
1099                 do {
1100                         cont = 0;
1101                         len = roaming_read(active_state->connection_in, buf,
1102                             sizeof(buf), &cont);
1103                 } while (len == 0 && cont);
1104                 if (len == 0) {
1105                         logit("Connection closed by %.200s", get_remote_ipaddr());
1106                         cleanup_exit(255);
1107                 }
1108                 if (len < 0)
1109                         fatal("Read from socket failed: %.100s", strerror(errno));
1110                 /* Append it to the buffer. */
1111                 packet_process_incoming(buf, len);
1112         }
1113         /* NOTREACHED */
1114 }
1115
1116 int
1117 packet_read(void)
1118 {
1119         return packet_read_seqnr(NULL);
1120 }
1121
1122 /*
1123  * Waits until a packet has been received, verifies that its type matches
1124  * that given, and gives a fatal error and exits if there is a mismatch.
1125  */
1126
1127 void
1128 packet_read_expect(int expected_type)
1129 {
1130         int type;
1131
1132         type = packet_read();
1133         if (type != expected_type)
1134                 packet_disconnect("Protocol error: expected packet type %d, got %d",
1135                     expected_type, type);
1136 }
1137
1138 /* Checks if a full packet is available in the data received so far via
1139  * packet_process_incoming.  If so, reads the packet; otherwise returns
1140  * SSH_MSG_NONE.  This does not wait for data from the connection.
1141  *
1142  * SSH_MSG_DISCONNECT is handled specially here.  Also,
1143  * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1144  * to higher levels.
1145  */
1146
1147 static int
1148 packet_read_poll1(void)
1149 {
1150         u_int len, padded_len;
1151         u_char *cp, type;
1152         u_int checksum, stored_checksum;
1153
1154         /* Check if input size is less than minimum packet size. */
1155         if (buffer_len(&active_state->input) < 4 + 8)
1156                 return SSH_MSG_NONE;
1157         /* Get length of incoming packet. */
1158         cp = buffer_ptr(&active_state->input);
1159         len = get_u32(cp);
1160         if (len < 1 + 2 + 2 || len > 256 * 1024)
1161                 packet_disconnect("Bad packet length %u.", len);
1162         padded_len = (len + 8) & ~7;
1163
1164         /* Check if the packet has been entirely received. */
1165         if (buffer_len(&active_state->input) < 4 + padded_len)
1166                 return SSH_MSG_NONE;
1167
1168         /* The entire packet is in buffer. */
1169
1170         /* Consume packet length. */
1171         buffer_consume(&active_state->input, 4);
1172
1173         /*
1174          * Cryptographic attack detector for ssh
1175          * (C)1998 CORE-SDI, Buenos Aires Argentina
1176          * Ariel Futoransky(futo@core-sdi.com)
1177          */
1178         if (!active_state->receive_context.plaintext) {
1179                 switch (detect_attack(buffer_ptr(&active_state->input),
1180                     padded_len)) {
1181                 case DEATTACK_DETECTED:
1182                         packet_disconnect("crc32 compensation attack: "
1183                             "network attack detected");
1184                 case DEATTACK_DOS_DETECTED:
1185                         packet_disconnect("deattack denial of "
1186                             "service detected");
1187                 }
1188         }
1189
1190         /* Decrypt data to incoming_packet. */
1191         buffer_clear(&active_state->incoming_packet);
1192         cp = buffer_append_space(&active_state->incoming_packet, padded_len);
1193         cipher_crypt(&active_state->receive_context, cp,
1194             buffer_ptr(&active_state->input), padded_len);
1195
1196         buffer_consume(&active_state->input, padded_len);
1197
1198 #ifdef PACKET_DEBUG
1199         fprintf(stderr, "read_poll plain: ");
1200         buffer_dump(&active_state->incoming_packet);
1201 #endif
1202
1203         /* Compute packet checksum. */
1204         checksum = ssh_crc32(buffer_ptr(&active_state->incoming_packet),
1205             buffer_len(&active_state->incoming_packet) - 4);
1206
1207         /* Skip padding. */
1208         buffer_consume(&active_state->incoming_packet, 8 - len % 8);
1209
1210         /* Test check bytes. */
1211         if (len != buffer_len(&active_state->incoming_packet))
1212                 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1213                     len, buffer_len(&active_state->incoming_packet));
1214
1215         cp = (u_char *)buffer_ptr(&active_state->incoming_packet) + len - 4;
1216         stored_checksum = get_u32(cp);
1217         if (checksum != stored_checksum)
1218                 packet_disconnect("Corrupted check bytes on input.");
1219         buffer_consume_end(&active_state->incoming_packet, 4);
1220
1221         if (active_state->packet_compression) {
1222                 buffer_clear(&active_state->compression_buffer);
1223                 buffer_uncompress(&active_state->incoming_packet,
1224                     &active_state->compression_buffer);
1225                 buffer_clear(&active_state->incoming_packet);
1226                 buffer_append(&active_state->incoming_packet,
1227                     buffer_ptr(&active_state->compression_buffer),
1228                     buffer_len(&active_state->compression_buffer));
1229         }
1230         active_state->p_read.packets++;
1231         active_state->p_read.bytes += padded_len + 4;
1232         type = buffer_get_char(&active_state->incoming_packet);
1233         if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1234                 packet_disconnect("Invalid ssh1 packet type: %d", type);
1235         return type;
1236 }
1237
1238 static int
1239 packet_read_poll2(u_int32_t *seqnr_p)
1240 {
1241         u_int padlen, need;
1242         u_char *macbuf, *cp, type;
1243         u_int maclen, block_size;
1244         Enc *enc   = NULL;
1245         Mac *mac   = NULL;
1246         Comp *comp = NULL;
1247
1248         if (active_state->packet_discard)
1249                 return SSH_MSG_NONE;
1250
1251         if (active_state->newkeys[MODE_IN] != NULL) {
1252                 enc  = &active_state->newkeys[MODE_IN]->enc;
1253                 mac  = &active_state->newkeys[MODE_IN]->mac;
1254                 comp = &active_state->newkeys[MODE_IN]->comp;
1255         }
1256         maclen = mac && mac->enabled ? mac->mac_len : 0;
1257         block_size = enc ? enc->block_size : 8;
1258
1259         if (active_state->packlen == 0) {
1260                 /*
1261                  * check if input size is less than the cipher block size,
1262                  * decrypt first block and extract length of incoming packet
1263                  */
1264                 if (buffer_len(&active_state->input) < block_size)
1265                         return SSH_MSG_NONE;
1266                 buffer_clear(&active_state->incoming_packet);
1267                 cp = buffer_append_space(&active_state->incoming_packet,
1268                     block_size);
1269                 cipher_crypt(&active_state->receive_context, cp,
1270                     buffer_ptr(&active_state->input), block_size);
1271                 cp = buffer_ptr(&active_state->incoming_packet);
1272                 active_state->packlen = get_u32(cp);
1273                 if (active_state->packlen < 1 + 4 ||
1274                     active_state->packlen > PACKET_MAX_SIZE) {
1275 #ifdef PACKET_DEBUG
1276                         buffer_dump(&active_state->incoming_packet);
1277 #endif
1278                         logit("Bad packet length %u.", active_state->packlen);
1279                         packet_start_discard(enc, mac, active_state->packlen,
1280                             PACKET_MAX_SIZE);
1281                         return SSH_MSG_NONE;
1282                 }
1283                 DBG(debug("input: packet len %u", active_state->packlen+4));
1284                 buffer_consume(&active_state->input, block_size);
1285         }
1286         /* we have a partial packet of block_size bytes */
1287         need = 4 + active_state->packlen - block_size;
1288         DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1289             need, maclen));
1290         if (need % block_size != 0) {
1291                 logit("padding error: need %d block %d mod %d",
1292                     need, block_size, need % block_size);
1293                 packet_start_discard(enc, mac, active_state->packlen,
1294                     PACKET_MAX_SIZE - block_size);
1295                 return SSH_MSG_NONE;
1296         }
1297         /*
1298          * check if the entire packet has been received and
1299          * decrypt into incoming_packet
1300          */
1301         if (buffer_len(&active_state->input) < need + maclen)
1302                 return SSH_MSG_NONE;
1303 #ifdef PACKET_DEBUG
1304         fprintf(stderr, "read_poll enc/full: ");
1305         buffer_dump(&active_state->input);
1306 #endif
1307         cp = buffer_append_space(&active_state->incoming_packet, need);
1308         cipher_crypt(&active_state->receive_context, cp,
1309             buffer_ptr(&active_state->input), need);
1310         buffer_consume(&active_state->input, need);
1311         /*
1312          * compute MAC over seqnr and packet,
1313          * increment sequence number for incoming packet
1314          */
1315         if (mac && mac->enabled) {
1316                 macbuf = mac_compute(mac, active_state->p_read.seqnr,
1317                     buffer_ptr(&active_state->incoming_packet),
1318                     buffer_len(&active_state->incoming_packet));
1319                 if (timingsafe_bcmp(macbuf, buffer_ptr(&active_state->input),
1320                     mac->mac_len) != 0) {
1321                         logit("Corrupted MAC on input.");
1322                         if (need > PACKET_MAX_SIZE)
1323                                 fatal("internal error need %d", need);
1324                         packet_start_discard(enc, mac, active_state->packlen,
1325                             PACKET_MAX_SIZE - need);
1326                         return SSH_MSG_NONE;
1327                 }
1328
1329                 DBG(debug("MAC #%d ok", active_state->p_read.seqnr));
1330                 buffer_consume(&active_state->input, mac->mac_len);
1331         }
1332         /* XXX now it's safe to use fatal/packet_disconnect */
1333         if (seqnr_p != NULL)
1334                 *seqnr_p = active_state->p_read.seqnr;
1335         if (++active_state->p_read.seqnr == 0)
1336                 logit("incoming seqnr wraps around");
1337         if (++active_state->p_read.packets == 0)
1338                 if (!(datafellows & SSH_BUG_NOREKEY))
1339                         fatal("XXX too many packets with same key");
1340         active_state->p_read.blocks += (active_state->packlen + 4) / block_size;
1341         active_state->p_read.bytes += active_state->packlen + 4;
1342
1343         /* get padlen */
1344         cp = buffer_ptr(&active_state->incoming_packet);
1345         padlen = cp[4];
1346         DBG(debug("input: padlen %d", padlen));
1347         if (padlen < 4)
1348                 packet_disconnect("Corrupted padlen %d on input.", padlen);
1349
1350         /* skip packet size + padlen, discard padding */
1351         buffer_consume(&active_state->incoming_packet, 4 + 1);
1352         buffer_consume_end(&active_state->incoming_packet, padlen);
1353
1354         DBG(debug("input: len before de-compress %d",
1355             buffer_len(&active_state->incoming_packet)));
1356         if (comp && comp->enabled) {
1357                 buffer_clear(&active_state->compression_buffer);
1358                 buffer_uncompress(&active_state->incoming_packet,
1359                     &active_state->compression_buffer);
1360                 buffer_clear(&active_state->incoming_packet);
1361                 buffer_append(&active_state->incoming_packet,
1362                     buffer_ptr(&active_state->compression_buffer),
1363                     buffer_len(&active_state->compression_buffer));
1364                 DBG(debug("input: len after de-compress %d",
1365                     buffer_len(&active_state->incoming_packet)));
1366         }
1367         /*
1368          * get packet type, implies consume.
1369          * return length of payload (without type field)
1370          */
1371         type = buffer_get_char(&active_state->incoming_packet);
1372         if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1373                 packet_disconnect("Invalid ssh2 packet type: %d", type);
1374         if (type == SSH2_MSG_NEWKEYS)
1375                 set_newkeys(MODE_IN);
1376         else if (type == SSH2_MSG_USERAUTH_SUCCESS &&
1377             !active_state->server_side)
1378                 packet_enable_delayed_compress();
1379 #ifdef PACKET_DEBUG
1380         fprintf(stderr, "read/plain[%d]:\r\n", type);
1381         buffer_dump(&active_state->incoming_packet);
1382 #endif
1383         /* reset for next packet */
1384         active_state->packlen = 0;
1385         return type;
1386 }
1387
1388 int
1389 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1390 {
1391         u_int reason, seqnr;
1392         u_char type;
1393         char *msg;
1394
1395         for (;;) {
1396                 if (compat20) {
1397                         type = packet_read_poll2(seqnr_p);
1398                         if (type) {
1399                                 active_state->keep_alive_timeouts = 0;
1400                                 DBG(debug("received packet type %d", type));
1401                         }
1402                         switch (type) {
1403                         case SSH2_MSG_IGNORE:
1404                                 debug3("Received SSH2_MSG_IGNORE");
1405                                 break;
1406                         case SSH2_MSG_DEBUG:
1407                                 packet_get_char();
1408                                 msg = packet_get_string(NULL);
1409                                 debug("Remote: %.900s", msg);
1410                                 xfree(msg);
1411                                 msg = packet_get_string(NULL);
1412                                 xfree(msg);
1413                                 break;
1414                         case SSH2_MSG_DISCONNECT:
1415                                 reason = packet_get_int();
1416                                 msg = packet_get_string(NULL);
1417                                 logit("Received disconnect from %s: %u: %.400s",
1418                                     get_remote_ipaddr(), reason, msg);
1419                                 xfree(msg);
1420                                 cleanup_exit(255);
1421                                 break;
1422                         case SSH2_MSG_UNIMPLEMENTED:
1423                                 seqnr = packet_get_int();
1424                                 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1425                                     seqnr);
1426                                 break;
1427                         default:
1428                                 return type;
1429                         }
1430                 } else {
1431                         type = packet_read_poll1();
1432                         switch (type) {
1433                         case SSH_MSG_IGNORE:
1434                                 break;
1435                         case SSH_MSG_DEBUG:
1436                                 msg = packet_get_string(NULL);
1437                                 debug("Remote: %.900s", msg);
1438                                 xfree(msg);
1439                                 break;
1440                         case SSH_MSG_DISCONNECT:
1441                                 msg = packet_get_string(NULL);
1442                                 logit("Received disconnect from %s: %.400s",
1443                                     get_remote_ipaddr(), msg);
1444                                 cleanup_exit(255);
1445                                 break;
1446                         default:
1447                                 if (type)
1448                                         DBG(debug("received packet type %d", type));
1449                                 return type;
1450                         }
1451                 }
1452         }
1453 }
1454
1455 int
1456 packet_read_poll(void)
1457 {
1458         return packet_read_poll_seqnr(NULL);
1459 }
1460
1461 /*
1462  * Buffers the given amount of input characters.  This is intended to be used
1463  * together with packet_read_poll.
1464  */
1465
1466 void
1467 packet_process_incoming(const char *buf, u_int len)
1468 {
1469         if (active_state->packet_discard) {
1470                 active_state->keep_alive_timeouts = 0; /* ?? */
1471                 if (len >= active_state->packet_discard)
1472                         packet_stop_discard();
1473                 active_state->packet_discard -= len;
1474                 return;
1475         }
1476         buffer_append(&active_state->input, buf, len);
1477 }
1478
1479 /* Returns a character from the packet. */
1480
1481 u_int
1482 packet_get_char(void)
1483 {
1484         char ch;
1485
1486         buffer_get(&active_state->incoming_packet, &ch, 1);
1487         return (u_char) ch;
1488 }
1489
1490 /* Returns an integer from the packet data. */
1491
1492 u_int
1493 packet_get_int(void)
1494 {
1495         return buffer_get_int(&active_state->incoming_packet);
1496 }
1497
1498 /* Returns an 64 bit integer from the packet data. */
1499
1500 u_int64_t
1501 packet_get_int64(void)
1502 {
1503         return buffer_get_int64(&active_state->incoming_packet);
1504 }
1505
1506 /*
1507  * Returns an arbitrary precision integer from the packet data.  The integer
1508  * must have been initialized before this call.
1509  */
1510
1511 void
1512 packet_get_bignum(BIGNUM * value)
1513 {
1514         buffer_get_bignum(&active_state->incoming_packet, value);
1515 }
1516
1517 void
1518 packet_get_bignum2(BIGNUM * value)
1519 {
1520         buffer_get_bignum2(&active_state->incoming_packet, value);
1521 }
1522
1523 #ifdef OPENSSL_HAS_ECC
1524 void
1525 packet_get_ecpoint(const EC_GROUP *curve, EC_POINT *point)
1526 {
1527         buffer_get_ecpoint(&active_state->incoming_packet, curve, point);
1528 }
1529 #endif
1530
1531 void *
1532 packet_get_raw(u_int *length_ptr)
1533 {
1534         u_int bytes = buffer_len(&active_state->incoming_packet);
1535
1536         if (length_ptr != NULL)
1537                 *length_ptr = bytes;
1538         return buffer_ptr(&active_state->incoming_packet);
1539 }
1540
1541 int
1542 packet_remaining(void)
1543 {
1544         return buffer_len(&active_state->incoming_packet);
1545 }
1546
1547 /*
1548  * Returns a string from the packet data.  The string is allocated using
1549  * xmalloc; it is the responsibility of the calling program to free it when
1550  * no longer needed.  The length_ptr argument may be NULL, or point to an
1551  * integer into which the length of the string is stored.
1552  */
1553
1554 void *
1555 packet_get_string(u_int *length_ptr)
1556 {
1557         return buffer_get_string(&active_state->incoming_packet, length_ptr);
1558 }
1559
1560 void *
1561 packet_get_string_ptr(u_int *length_ptr)
1562 {
1563         return buffer_get_string_ptr(&active_state->incoming_packet, length_ptr);
1564 }
1565
1566 /* Ensures the returned string has no embedded \0 characters in it. */
1567 char *
1568 packet_get_cstring(u_int *length_ptr)
1569 {
1570         return buffer_get_cstring(&active_state->incoming_packet, length_ptr);
1571 }
1572
1573 /*
1574  * Sends a diagnostic message from the server to the client.  This message
1575  * can be sent at any time (but not while constructing another message). The
1576  * message is printed immediately, but only if the client is being executed
1577  * in verbose mode.  These messages are primarily intended to ease debugging
1578  * authentication problems.   The length of the formatted message must not
1579  * exceed 1024 bytes.  This will automatically call packet_write_wait.
1580  */
1581
1582 void
1583 packet_send_debug(const char *fmt,...)
1584 {
1585         char buf[1024];
1586         va_list args;
1587
1588         if (compat20 && (datafellows & SSH_BUG_DEBUG))
1589                 return;
1590
1591         va_start(args, fmt);
1592         vsnprintf(buf, sizeof(buf), fmt, args);
1593         va_end(args);
1594
1595         if (compat20) {
1596                 packet_start(SSH2_MSG_DEBUG);
1597                 packet_put_char(0);     /* bool: always display */
1598                 packet_put_cstring(buf);
1599                 packet_put_cstring("");
1600         } else {
1601                 packet_start(SSH_MSG_DEBUG);
1602                 packet_put_cstring(buf);
1603         }
1604         packet_send();
1605         packet_write_wait();
1606 }
1607
1608 /*
1609  * Logs the error plus constructs and sends a disconnect packet, closes the
1610  * connection, and exits.  This function never returns. The error message
1611  * should not contain a newline.  The length of the formatted message must
1612  * not exceed 1024 bytes.
1613  */
1614
1615 void
1616 packet_disconnect(const char *fmt,...)
1617 {
1618         char buf[1024];
1619         va_list args;
1620         static int disconnecting = 0;
1621
1622         if (disconnecting)      /* Guard against recursive invocations. */
1623                 fatal("packet_disconnect called recursively.");
1624         disconnecting = 1;
1625
1626         /*
1627          * Format the message.  Note that the caller must make sure the
1628          * message is of limited size.
1629          */
1630         va_start(args, fmt);
1631         vsnprintf(buf, sizeof(buf), fmt, args);
1632         va_end(args);
1633
1634         /* Display the error locally */
1635         logit("Disconnecting: %.100s", buf);
1636
1637         /* Send the disconnect message to the other side, and wait for it to get sent. */
1638         if (compat20) {
1639                 packet_start(SSH2_MSG_DISCONNECT);
1640                 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1641                 packet_put_cstring(buf);
1642                 packet_put_cstring("");
1643         } else {
1644                 packet_start(SSH_MSG_DISCONNECT);
1645                 packet_put_cstring(buf);
1646         }
1647         packet_send();
1648         packet_write_wait();
1649
1650         /* Stop listening for connections. */
1651         channel_close_all();
1652
1653         /* Close the connection. */
1654         packet_close();
1655         cleanup_exit(255);
1656 }
1657
1658 /* Checks if there is any buffered output, and tries to write some of the output. */
1659
1660 void
1661 packet_write_poll(void)
1662 {
1663         int len = buffer_len(&active_state->output);
1664         int cont;
1665
1666         if (len > 0) {
1667                 cont = 0;
1668                 len = roaming_write(active_state->connection_out,
1669                     buffer_ptr(&active_state->output), len, &cont);
1670                 if (len == -1) {
1671                         if (errno == EINTR || errno == EAGAIN ||
1672                             errno == EWOULDBLOCK)
1673                                 return;
1674                         fatal("Write failed: %.100s", strerror(errno));
1675                 }
1676                 if (len == 0 && !cont)
1677                         fatal("Write connection closed");
1678                 buffer_consume(&active_state->output, len);
1679         }
1680 }
1681
1682 /*
1683  * Calls packet_write_poll repeatedly until all pending output data has been
1684  * written.
1685  */
1686
1687 void
1688 packet_write_wait(void)
1689 {
1690         fd_set *setp;
1691         int ret, ms_remain;
1692         struct timeval start, timeout, *timeoutp = NULL;
1693
1694         setp = (fd_set *)xcalloc(howmany(active_state->connection_out + 1,
1695             NFDBITS), sizeof(fd_mask));
1696         packet_write_poll();
1697         while (packet_have_data_to_write()) {
1698                 memset(setp, 0, howmany(active_state->connection_out + 1,
1699                     NFDBITS) * sizeof(fd_mask));
1700                 FD_SET(active_state->connection_out, setp);
1701
1702                 if (active_state->packet_timeout_ms > 0) {
1703                         ms_remain = active_state->packet_timeout_ms;
1704                         timeoutp = &timeout;
1705                 }
1706                 for (;;) {
1707                         if (active_state->packet_timeout_ms != -1) {
1708                                 ms_to_timeval(&timeout, ms_remain);
1709                                 gettimeofday(&start, NULL);
1710                         }
1711                         if ((ret = select(active_state->connection_out + 1,
1712                             NULL, setp, NULL, timeoutp)) >= 0)
1713                                 break;
1714                         if (errno != EAGAIN && errno != EINTR &&
1715                             errno != EWOULDBLOCK)
1716                                 break;
1717                         if (active_state->packet_timeout_ms == -1)
1718                                 continue;
1719                         ms_subtract_diff(&start, &ms_remain);
1720                         if (ms_remain <= 0) {
1721                                 ret = 0;
1722                                 break;
1723                         }
1724                 }
1725                 if (ret == 0) {
1726                         logit("Connection to %.200s timed out while "
1727                             "waiting to write", get_remote_ipaddr());
1728                         cleanup_exit(255);
1729                 }
1730                 packet_write_poll();
1731         }
1732         xfree(setp);
1733 }
1734
1735 /* Returns true if there is buffered data to write to the connection. */
1736
1737 int
1738 packet_have_data_to_write(void)
1739 {
1740         return buffer_len(&active_state->output) != 0;
1741 }
1742
1743 /* Returns true if there is not too much data to write to the connection. */
1744
1745 int
1746 packet_not_very_much_data_to_write(void)
1747 {
1748         if (active_state->interactive_mode)
1749                 return buffer_len(&active_state->output) < 16384;
1750         else
1751                 return buffer_len(&active_state->output) < 128 * 1024;
1752 }
1753
1754 static void
1755 packet_set_tos(int tos)
1756 {
1757 #ifndef IP_TOS_IS_BROKEN
1758         if (!packet_connection_is_on_socket())
1759                 return;
1760         switch (packet_connection_af()) {
1761 # ifdef IP_TOS
1762         case AF_INET:
1763                 debug3("%s: set IP_TOS 0x%02x", __func__, tos);
1764                 if (setsockopt(active_state->connection_in,
1765                     IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) < 0)
1766                         error("setsockopt IP_TOS %d: %.100s:",
1767                             tos, strerror(errno));
1768                 break;
1769 # endif /* IP_TOS */
1770 # ifdef IPV6_TCLASS
1771         case AF_INET6:
1772                 debug3("%s: set IPV6_TCLASS 0x%02x", __func__, tos);
1773                 if (setsockopt(active_state->connection_in,
1774                     IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos)) < 0)
1775                         error("setsockopt IPV6_TCLASS %d: %.100s:",
1776                             tos, strerror(errno));
1777                 break;
1778 # endif /* IPV6_TCLASS */
1779         }
1780 #endif /* IP_TOS_IS_BROKEN */
1781 }
1782
1783 /* Informs that the current session is interactive.  Sets IP flags for that. */
1784
1785 void
1786 packet_set_interactive(int interactive, int qos_interactive, int qos_bulk)
1787 {
1788         if (active_state->set_interactive_called)
1789                 return;
1790         active_state->set_interactive_called = 1;
1791
1792         /* Record that we are in interactive mode. */
1793         active_state->interactive_mode = interactive;
1794
1795         /* Only set socket options if using a socket.  */
1796         if (!packet_connection_is_on_socket())
1797                 return;
1798         set_nodelay(active_state->connection_in);
1799         packet_set_tos(interactive ? qos_interactive : qos_bulk);
1800 }
1801
1802 /* Returns true if the current connection is interactive. */
1803
1804 int
1805 packet_is_interactive(void)
1806 {
1807         return active_state->interactive_mode;
1808 }
1809
1810 int
1811 packet_set_maxsize(u_int s)
1812 {
1813         if (active_state->set_maxsize_called) {
1814                 logit("packet_set_maxsize: called twice: old %d new %d",
1815                     active_state->max_packet_size, s);
1816                 return -1;
1817         }
1818         if (s < 4 * 1024 || s > 1024 * 1024) {
1819                 logit("packet_set_maxsize: bad size %d", s);
1820                 return -1;
1821         }
1822         active_state->set_maxsize_called = 1;
1823         debug("packet_set_maxsize: setting to %d", s);
1824         active_state->max_packet_size = s;
1825         return s;
1826 }
1827
1828 int
1829 packet_inc_alive_timeouts(void)
1830 {
1831         return ++active_state->keep_alive_timeouts;
1832 }
1833
1834 void
1835 packet_set_alive_timeouts(int ka)
1836 {
1837         active_state->keep_alive_timeouts = ka;
1838 }
1839
1840 u_int
1841 packet_get_maxsize(void)
1842 {
1843         return active_state->max_packet_size;
1844 }
1845
1846 /* roundup current message to pad bytes */
1847 void
1848 packet_add_padding(u_char pad)
1849 {
1850         active_state->extra_pad = pad;
1851 }
1852
1853 /*
1854  * 9.2.  Ignored Data Message
1855  *
1856  *   byte      SSH_MSG_IGNORE
1857  *   string    data
1858  *
1859  * All implementations MUST understand (and ignore) this message at any
1860  * time (after receiving the protocol version). No implementation is
1861  * required to send them. This message can be used as an additional
1862  * protection measure against advanced traffic analysis techniques.
1863  */
1864 void
1865 packet_send_ignore(int nbytes)
1866 {
1867         u_int32_t rnd = 0;
1868         int i;
1869
1870         packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1871         packet_put_int(nbytes);
1872         for (i = 0; i < nbytes; i++) {
1873                 if (i % 4 == 0)
1874                         rnd = arc4random();
1875                 packet_put_char((u_char)rnd & 0xff);
1876                 rnd >>= 8;
1877         }
1878 }
1879
1880 #ifdef  NONE_CIPHER_ENABLED
1881 void
1882 packet_request_rekeying(void)
1883 {
1884         rekey_requested = 1;
1885 }
1886 #endif
1887
1888 #define MAX_PACKETS     (1U<<31)
1889 int
1890 packet_need_rekeying(void)
1891 {
1892         if (datafellows & SSH_BUG_NOREKEY)
1893                 return 0;
1894 #ifdef  NONE_CIPHER_ENABLED
1895         if (rekey_requested == 1) {
1896                 rekey_requested = 0;
1897                 return 1;
1898         }
1899 #endif
1900         return
1901             (active_state->p_send.packets > MAX_PACKETS) ||
1902             (active_state->p_read.packets > MAX_PACKETS) ||
1903             (active_state->max_blocks_out &&
1904                 (active_state->p_send.blocks > active_state->max_blocks_out)) ||
1905             (active_state->max_blocks_in &&
1906                 (active_state->p_read.blocks > active_state->max_blocks_in));
1907 }
1908
1909 void
1910 packet_set_rekey_limit(u_int32_t bytes)
1911 {
1912         active_state->rekey_limit = bytes;
1913 }
1914
1915 void
1916 packet_set_server(void)
1917 {
1918         active_state->server_side = 1;
1919 }
1920
1921 void
1922 packet_set_authenticated(void)
1923 {
1924         active_state->after_authentication = 1;
1925 }
1926
1927 void *
1928 packet_get_input(void)
1929 {
1930         return (void *)&active_state->input;
1931 }
1932
1933 void *
1934 packet_get_output(void)
1935 {
1936         return (void *)&active_state->output;
1937 }
1938
1939 void *
1940 packet_get_newkeys(int mode)
1941 {
1942         return (void *)active_state->newkeys[mode];
1943 }
1944
1945 /*
1946  * Save the state for the real connection, and use a separate state when
1947  * resuming a suspended connection.
1948  */
1949 void
1950 packet_backup_state(void)
1951 {
1952         struct session_state *tmp;
1953
1954         close(active_state->connection_in);
1955         active_state->connection_in = -1;
1956         close(active_state->connection_out);
1957         active_state->connection_out = -1;
1958         if (backup_state)
1959                 tmp = backup_state;
1960         else
1961                 tmp = alloc_session_state();
1962         backup_state = active_state;
1963         active_state = tmp;
1964 }
1965
1966 /*
1967  * Swap in the old state when resuming a connecion.
1968  */
1969 void
1970 packet_restore_state(void)
1971 {
1972         struct session_state *tmp;
1973         void *buf;
1974         u_int len;
1975
1976         tmp = backup_state;
1977         backup_state = active_state;
1978         active_state = tmp;
1979         active_state->connection_in = backup_state->connection_in;
1980         backup_state->connection_in = -1;
1981         active_state->connection_out = backup_state->connection_out;
1982         backup_state->connection_out = -1;
1983         len = buffer_len(&backup_state->input);
1984         if (len > 0) {
1985                 buf = buffer_ptr(&backup_state->input);
1986                 buffer_append(&active_state->input, buf, len);
1987                 buffer_clear(&backup_state->input);
1988                 add_recv_bytes(len);
1989         }
1990 }
1991
1992 #ifdef  NONE_CIPHER_ENABLED
1993 int
1994 packet_get_authentication_state(void)
1995 {
1996         return (active_state->after_authentication);
1997 }
1998 #endif