openssh/packet.c

   1 /* $OpenBSD: packet.c,v 1.166 2009/06/27 09:29:06 andreas Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains code implementing the packet protocol and communication
   7  * with the other side.  This same code is used both on client and server side.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  *
  16  * SSH2 packet format added by Markus Friedl.
  17  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  18  *
  19  * Redistribution and use in source and binary forms, with or without
  20  * modification, are permitted provided that the following conditions
  21  * are met:
  22  * 1. Redistributions of source code must retain the above copyright
  23  *    notice, this list of conditions and the following disclaimer.
  24  * 2. Redistributions in binary form must reproduce the above copyright
  25  *    notice, this list of conditions and the following disclaimer in the
  26  *    documentation and/or other materials provided with the distribution.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  29  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  30  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  31  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  32  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  33  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  34  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  35  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  36  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  37  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  38  */
  39
  40 #include "includes.h"
  41
  42 #include <sys/types.h>
  43 #include "openbsd-compat/sys-queue.h"
  44 #include <sys/param.h>
  45 #include <sys/socket.h>
  46 #ifdef HAVE_SYS_TIME_H
  47 # include <sys/time.h>
  48 #endif
  49
  50 #include <netinet/in.h>
  51 #include <netinet/ip.h>
  52 #include <arpa/inet.h>
  53
  54 #include <errno.h>
  55 #include <stdarg.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59 #include <unistd.h>
  60 #include <signal.h>
  61
  62 #include "xmalloc.h"
  63 #include "buffer.h"
  64 #include "packet.h"
  65 #include "crc32.h"
  66 #include "compress.h"
  67 #include "deattack.h"
  68 #include "channels.h"
  69 #include "compat.h"
  70 #include "ssh1.h"
  71 #include "ssh2.h"
  72 #include "cipher.h"
  73 #include "key.h"
  74 #include "kex.h"
  75 #include "mac.h"
  76 #include "log.h"
  77 #include "canohost.h"
  78 #include "misc.h"
  79 #include "ssh.h"
  80 #include "roaming.h"
  81
  82 #ifdef PACKET_DEBUG
  83 #define DBG(x) x
  84 #else
  85 #define DBG(x)
  86 #endif
  87
  88 #define PACKET_MAX_SIZE (256 * 1024)
  89
  90 struct packet_state {
  91         u_int32_t seqnr;
  92         u_int32_t packets;
  93         u_int64_t blocks;
  94         u_int64_t bytes;
  95 };
  96
  97 struct packet {
  98         TAILQ_ENTRY(packet) next;
  99         u_char type;
 100         Buffer payload;
 101 };
 102
 103 struct session_state {
 104         /*
 105          * This variable contains the file descriptors used for
 106          * communicating with the other side.  connection_in is used for
 107          * reading; connection_out for writing.  These can be the same
 108          * descriptor, in which case it is assumed to be a socket.
 109          */
 110         int connection_in;
 111         int connection_out;
 112
 113         /* Protocol flags for the remote side. */
 114         u_int remote_protocol_flags;
 115
 116         /* Encryption context for receiving data.  Only used for decryption. */
 117         CipherContext receive_context;
 118
 119         /* Encryption context for sending data.  Only used for encryption. */
 120         CipherContext send_context;
 121
 122         /* Buffer for raw input data from the socket. */
 123         Buffer input;
 124
 125         /* Buffer for raw output data going to the socket. */
 126         Buffer output;
 127
 128         /* Buffer for the partial outgoing packet being constructed. */
 129         Buffer outgoing_packet;
 130
 131         /* Buffer for the incoming packet currently being processed. */
 132         Buffer incoming_packet;
 133
 134         /* Scratch buffer for packet compression/decompression. */
 135         Buffer compression_buffer;
 136         int compression_buffer_ready;
 137
 138         /*
 139          * Flag indicating whether packet compression/decompression is
 140          * enabled.
 141          */
 142         int packet_compression;
 143
 144         /* default maximum packet size */
 145         u_int max_packet_size;
 146
 147         /* Flag indicating whether this module has been initialized. */
 148         int initialized;
 149
 150         /* Set to true if the connection is interactive. */
 151         int interactive_mode;
 152
 153         /* Set to true if we are the server side. */
 154         int server_side;
 155
 156         /* Set to true if we are authenticated. */
 157         int after_authentication;
 158
 159         int keep_alive_timeouts;
 160
 161         /* The maximum time that we will wait to send or receive a packet */
 162         int packet_timeout_ms;
 163
 164         /* Session key information for Encryption and MAC */
 165         Newkeys *newkeys[MODE_MAX];
 166         struct packet_state p_read, p_send;
 167
 168         u_int64_t max_blocks_in, max_blocks_out;
 169         u_int32_t rekey_limit;
 170
 171         /* Session key for protocol v1 */
 172         u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
 173         u_int ssh1_keylen;
 174
 175         /* roundup current message to extra_pad bytes */
 176         u_char extra_pad;
 177
 178         /* XXX discard incoming data after MAC error */
 179         u_int packet_discard;
 180         Mac *packet_discard_mac;
 181
 182         /* Used in packet_read_poll2() */
 183         u_int packlen;
 184
 185         /* Used in packet_send2 */
 186         int rekeying;
 187
 188         /* Used in packet_set_interactive */
 189         int set_interactive_called;
 190
 191         /* Used in packet_set_maxsize */
 192         int set_maxsize_called;
 193
 194         TAILQ_HEAD(, packet) outgoing;
 195 };
 196
 197 static struct session_state *active_state, *backup_state;
 198
 199 static struct session_state *
 200 alloc_session_state(void)
 201 {
 202     struct session_state *s = xcalloc(1, sizeof(*s));
 203
 204     s->connection_in = -1;
 205     s->connection_out = -1;
 206     s->max_packet_size = 32768;
 207     s->packet_timeout_ms = -1;
 208     return s;
 209 }
 210
 211 /*
 212  * Sets the descriptors used for communication.  Disables encryption until
 213  * packet_set_encryption_key is called.
 214  */
 215 void
 216 packet_set_connection(int fd_in, int fd_out)
 217 {
 218         Cipher *none = cipher_by_name("none");
 219
 220         if (none == NULL)
 221                 fatal("packet_set_connection: cannot load cipher 'none'");
 222         if (active_state == NULL)
 223                 active_state = alloc_session_state();
 224         active_state->connection_in = fd_in;
 225         active_state->connection_out = fd_out;
 226         cipher_init(&active_state->send_context, none, (const u_char *)"",
 227             0, NULL, 0, CIPHER_ENCRYPT);
 228         cipher_init(&active_state->receive_context, none, (const u_char *)"",
 229             0, NULL, 0, CIPHER_DECRYPT);
 230         active_state->newkeys[MODE_IN] = active_state->newkeys[MODE_OUT] = NULL;
 231         if (!active_state->initialized) {
 232                 active_state->initialized = 1;
 233                 buffer_init(&active_state->input);
 234                 buffer_init(&active_state->output);
 235                 buffer_init(&active_state->outgoing_packet);
 236                 buffer_init(&active_state->incoming_packet);
 237                 TAILQ_INIT(&active_state->outgoing);
 238                 active_state->p_send.packets = active_state->p_read.packets = 0;
 239         }
 240 }
 241
 242 void
 243 packet_set_timeout(int timeout, int count)
 244 {
 245         if (timeout == 0 || count == 0) {
 246                 active_state->packet_timeout_ms = -1;
 247                 return;
 248         }
 249         if ((INT_MAX / 1000) / count < timeout)
 250                 active_state->packet_timeout_ms = INT_MAX;
 251         else
 252                 active_state->packet_timeout_ms = timeout * count * 1000;
 253 }
 254
 255 static void
 256 packet_stop_discard(void)
 257 {
 258         if (active_state->packet_discard_mac) {
 259                 char buf[1024];
 260
 261                 memset(buf, 'a', sizeof(buf));
 262                 while (buffer_len(&active_state->incoming_packet) <
 263                     PACKET_MAX_SIZE)
 264                         buffer_append(&active_state->incoming_packet, buf,
 265                             sizeof(buf));
 266                 (void) mac_compute(active_state->packet_discard_mac,
 267                     active_state->p_read.seqnr,
 268                     buffer_ptr(&active_state->incoming_packet),
 269                     PACKET_MAX_SIZE);
 270         }
 271         logit("Finished discarding for %.200s", get_remote_ipaddr());
 272         cleanup_exit(255);
 273 }
 274
 275 static void
 276 packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard)
 277 {
 278         if (enc == NULL || !cipher_is_cbc(enc->cipher))
 279                 packet_disconnect("Packet corrupt");
 280         if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
 281                 active_state->packet_discard_mac = mac;
 282         if (buffer_len(&active_state->input) >= discard)
 283                 packet_stop_discard();
 284         active_state->packet_discard = discard -
 285             buffer_len(&active_state->input);
 286 }
 287
 288 /* Returns 1 if remote host is connected via socket, 0 if not. */
 289
 290 int
 291 packet_connection_is_on_socket(void)
 292 {
 293         struct sockaddr_storage from, to;
 294         socklen_t fromlen, tolen;
 295
 296         /* filedescriptors in and out are the same, so it's a socket */
 297         if (active_state->connection_in == active_state->connection_out)
 298                 return 1;
 299         fromlen = sizeof(from);
 300         memset(&from, 0, sizeof(from));
 301         if (getpeername(active_state->connection_in, (struct sockaddr *)&from,
 302             &fromlen) < 0)
 303                 return 0;
 304         tolen = sizeof(to);
 305         memset(&to, 0, sizeof(to));
 306         if (getpeername(active_state->connection_out, (struct sockaddr *)&to,
 307             &tolen) < 0)
 308                 return 0;
 309         if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
 310                 return 0;
 311         if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
 312                 return 0;
 313         return 1;
 314 }
 315
 316 /*
 317  * Exports an IV from the CipherContext required to export the key
 318  * state back from the unprivileged child to the privileged parent
 319  * process.
 320  */
 321
 322 void
 323 packet_get_keyiv(int mode, u_char *iv, u_int len)
 324 {
 325         CipherContext *cc;
 326
 327         if (mode == MODE_OUT)
 328                 cc = &active_state->send_context;
 329         else
 330                 cc = &active_state->receive_context;
 331
 332         cipher_get_keyiv(cc, iv, len);
 333 }
 334
 335 int
 336 packet_get_keycontext(int mode, u_char *dat)
 337 {
 338         CipherContext *cc;
 339
 340         if (mode == MODE_OUT)
 341                 cc = &active_state->send_context;
 342         else
 343                 cc = &active_state->receive_context;
 344
 345         return (cipher_get_keycontext(cc, dat));
 346 }
 347
 348 void
 349 packet_set_keycontext(int mode, u_char *dat)
 350 {
 351         CipherContext *cc;
 352
 353         if (mode == MODE_OUT)
 354                 cc = &active_state->send_context;
 355         else
 356                 cc = &active_state->receive_context;
 357
 358         cipher_set_keycontext(cc, dat);
 359 }
 360
 361 int
 362 packet_get_keyiv_len(int mode)
 363 {
 364         CipherContext *cc;
 365
 366         if (mode == MODE_OUT)
 367                 cc = &active_state->send_context;
 368         else
 369                 cc = &active_state->receive_context;
 370
 371         return (cipher_get_keyiv_len(cc));
 372 }
 373
 374 void
 375 packet_set_iv(int mode, u_char *dat)
 376 {
 377         CipherContext *cc;
 378
 379         if (mode == MODE_OUT)
 380                 cc = &active_state->send_context;
 381         else
 382                 cc = &active_state->receive_context;
 383
 384         cipher_set_keyiv(cc, dat);
 385 }
 386
 387 int
 388 packet_get_ssh1_cipher(void)
 389 {
 390         return (cipher_get_number(active_state->receive_context.cipher));
 391 }
 392
 393 void
 394 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets,
 395     u_int64_t *bytes)
 396 {
 397         struct packet_state *state;
 398
 399         state = (mode == MODE_IN) ?
 400             &active_state->p_read : &active_state->p_send;
 401         if (seqnr)
 402                 *seqnr = state->seqnr;
 403         if (blocks)
 404                 *blocks = state->blocks;
 405         if (packets)
 406                 *packets = state->packets;
 407         if (bytes)
 408                 *bytes = state->bytes;
 409 }
 410
 411 void
 412 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
 413     u_int64_t bytes)
 414 {
 415         struct packet_state *state;
 416
 417         state = (mode == MODE_IN) ?
 418             &active_state->p_read : &active_state->p_send;
 419         state->seqnr = seqnr;
 420         state->blocks = blocks;
 421         state->packets = packets;
 422         state->bytes = bytes;
 423 }
 424
 425 /* returns 1 if connection is via ipv4 */
 426
 427 int
 428 packet_connection_is_ipv4(void)
 429 {
 430         struct sockaddr_storage to;
 431         socklen_t tolen = sizeof(to);
 432
 433         memset(&to, 0, sizeof(to));
 434         if (getsockname(active_state->connection_out, (struct sockaddr *)&to,
 435             &tolen) < 0)
 436                 return 0;
 437         if (to.ss_family == AF_INET)
 438                 return 1;
 439 #ifdef IPV4_IN_IPV6
 440         if (to.ss_family == AF_INET6 &&
 441             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
 442                 return 1;
 443 #endif
 444         return 0;
 445 }
 446
 447 /* Sets the connection into non-blocking mode. */
 448
 449 void
 450 packet_set_nonblocking(void)
 451 {
 452         /* Set the socket into non-blocking mode. */
 453         set_nonblock(active_state->connection_in);
 454
 455         if (active_state->connection_out != active_state->connection_in)
 456                 set_nonblock(active_state->connection_out);
 457 }
 458
 459 /* Returns the socket used for reading. */
 460
 461 int
 462 packet_get_connection_in(void)
 463 {
 464         return active_state->connection_in;
 465 }
 466
 467 /* Returns the descriptor used for writing. */
 468
 469 int
 470 packet_get_connection_out(void)
 471 {
 472         return active_state->connection_out;
 473 }
 474
 475 /* Closes the connection and clears and frees internal data structures. */
 476
 477 void
 478 packet_close(void)
 479 {
 480         if (!active_state->initialized)
 481                 return;
 482         active_state->initialized = 0;
 483         if (active_state->connection_in == active_state->connection_out) {
 484                 shutdown(active_state->connection_out, SHUT_RDWR);
 485                 close(active_state->connection_out);
 486         } else {
 487                 close(active_state->connection_in);
 488                 close(active_state->connection_out);
 489         }
 490         buffer_free(&active_state->input);
 491         buffer_free(&active_state->output);
 492         buffer_free(&active_state->outgoing_packet);
 493         buffer_free(&active_state->incoming_packet);
 494         if (active_state->compression_buffer_ready) {
 495                 buffer_free(&active_state->compression_buffer);
 496                 buffer_compress_uninit();
 497         }
 498         cipher_cleanup(&active_state->send_context);
 499         cipher_cleanup(&active_state->receive_context);
 500 }
 501
 502 /* Sets remote side protocol flags. */
 503
 504 void
 505 packet_set_protocol_flags(u_int protocol_flags)
 506 {
 507         active_state->remote_protocol_flags = protocol_flags;
 508 }
 509
 510 /* Returns the remote protocol flags set earlier by the above function. */
 511
 512 u_int
 513 packet_get_protocol_flags(void)
 514 {
 515         return active_state->remote_protocol_flags;
 516 }
 517
 518 /*
 519  * Starts packet compression from the next packet on in both directions.
 520  * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
 521  */
 522
 523 static void
 524 packet_init_compression(void)
 525 {
 526         if (active_state->compression_buffer_ready == 1)
 527                 return;
 528         active_state->compression_buffer_ready = 1;
 529         buffer_init(&active_state->compression_buffer);
 530 }
 531
 532 void
 533 packet_start_compression(int level)
 534 {
 535         if (active_state->packet_compression && !compat20)
 536                 fatal("Compression already enabled.");
 537         active_state->packet_compression = 1;
 538         packet_init_compression();
 539         buffer_compress_init_send(level);
 540         buffer_compress_init_recv();
 541 }
 542
 543 /*
 544  * Causes any further packets to be encrypted using the given key.  The same
 545  * key is used for both sending and reception.  However, both directions are
 546  * encrypted independently of each other.
 547  */
 548
 549 void
 550 packet_set_encryption_key(const u_char *key, u_int keylen,
 551     int number)
 552 {
 553         Cipher *cipher = cipher_by_number(number);
 554
 555         if (cipher == NULL)
 556                 fatal("packet_set_encryption_key: unknown cipher number %d", number);
 557         if (keylen < 20)
 558                 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
 559         if (keylen > SSH_SESSION_KEY_LENGTH)
 560                 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
 561         memcpy(active_state->ssh1_key, key, keylen);
 562         active_state->ssh1_keylen = keylen;
 563         cipher_init(&active_state->send_context, cipher, key, keylen, NULL,
 564             0, CIPHER_ENCRYPT);
 565         cipher_init(&active_state->receive_context, cipher, key, keylen, NULL,
 566             0, CIPHER_DECRYPT);
 567 }
 568
 569 u_int
 570 packet_get_encryption_key(u_char *key)
 571 {
 572         if (key == NULL)
 573                 return (active_state->ssh1_keylen);
 574         memcpy(key, active_state->ssh1_key, active_state->ssh1_keylen);
 575         return (active_state->ssh1_keylen);
 576 }
 577
 578 /* Start constructing a packet to send. */
 579 void
 580 packet_start(u_char type)
 581 {
 582         u_char buf[9];
 583         int len;
 584
 585         DBG(debug("packet_start[%d]", type));
 586         len = compat20 ? 6 : 9;
 587         memset(buf, 0, len - 1);
 588         buf[len - 1] = type;
 589         buffer_clear(&active_state->outgoing_packet);
 590         buffer_append(&active_state->outgoing_packet, buf, len);
 591 }
 592
 593 /* Append payload. */
 594 void
 595 packet_put_char(int value)
 596 {
 597         char ch = value;
 598
 599         buffer_append(&active_state->outgoing_packet, &ch, 1);
 600 }
 601
 602 void
 603 packet_put_int(u_int value)
 604 {
 605         buffer_put_int(&active_state->outgoing_packet, value);
 606 }
 607
 608 void
 609 packet_put_int64(u_int64_t value)
 610 {
 611         buffer_put_int64(&active_state->outgoing_packet, value);
 612 }
 613
 614 void
 615 packet_put_string(const void *buf, u_int len)
 616 {
 617         buffer_put_string(&active_state->outgoing_packet, buf, len);
 618 }
 619
 620 void
 621 packet_put_cstring(const char *str)
 622 {
 623         buffer_put_cstring(&active_state->outgoing_packet, str);
 624 }
 625
 626 void
 627 packet_put_raw(const void *buf, u_int len)
 628 {
 629         buffer_append(&active_state->outgoing_packet, buf, len);
 630 }
 631
 632 void
 633 packet_put_bignum(BIGNUM * value)
 634 {
 635         buffer_put_bignum(&active_state->outgoing_packet, value);
 636 }
 637
 638 void
 639 packet_put_bignum2(BIGNUM * value)
 640 {
 641         buffer_put_bignum2(&active_state->outgoing_packet, value);
 642 }
 643
 644 /*
 645  * Finalizes and sends the packet.  If the encryption key has been set,
 646  * encrypts the packet before sending.
 647  */
 648
 649 static void
 650 packet_send1(void)
 651 {
 652         u_char buf[8], *cp;
 653         int i, padding, len;
 654         u_int checksum;
 655         u_int32_t rnd = 0;
 656
 657         /*
 658          * If using packet compression, compress the payload of the outgoing
 659          * packet.
 660          */
 661         if (active_state->packet_compression) {
 662                 buffer_clear(&active_state->compression_buffer);
 663                 /* Skip padding. */
 664                 buffer_consume(&active_state->outgoing_packet, 8);
 665                 /* padding */
 666                 buffer_append(&active_state->compression_buffer,
 667                     "\0\0\0\0\0\0\0\0", 8);
 668                 buffer_compress(&active_state->outgoing_packet,
 669                     &active_state->compression_buffer);
 670                 buffer_clear(&active_state->outgoing_packet);
 671                 buffer_append(&active_state->outgoing_packet,
 672                     buffer_ptr(&active_state->compression_buffer),
 673                     buffer_len(&active_state->compression_buffer));
 674         }
 675         /* Compute packet length without padding (add checksum, remove padding). */
 676         len = buffer_len(&active_state->outgoing_packet) + 4 - 8;
 677
 678         /* Insert padding. Initialized to zero in packet_start1() */
 679         padding = 8 - len % 8;
 680         if (!active_state->send_context.plaintext) {
 681                 cp = buffer_ptr(&active_state->outgoing_packet);
 682                 for (i = 0; i < padding; i++) {
 683                         if (i % 4 == 0)
 684                                 rnd = arc4random();
 685                         cp[7 - i] = rnd & 0xff;
 686                         rnd >>= 8;
 687                 }
 688         }
 689         buffer_consume(&active_state->outgoing_packet, 8 - padding);
 690
 691         /* Add check bytes. */
 692         checksum = ssh_crc32(buffer_ptr(&active_state->outgoing_packet),
 693             buffer_len(&active_state->outgoing_packet));
 694         put_u32(buf, checksum);
 695         buffer_append(&active_state->outgoing_packet, buf, 4);
 696
 697 #ifdef PACKET_DEBUG
 698         fprintf(stderr, "packet_send plain: ");
 699         buffer_dump(&active_state->outgoing_packet);
 700 #endif
 701
 702         /* Append to output. */
 703         put_u32(buf, len);
 704         buffer_append(&active_state->output, buf, 4);
 705         cp = buffer_append_space(&active_state->output,
 706             buffer_len(&active_state->outgoing_packet));
 707         cipher_crypt(&active_state->send_context, cp,
 708             buffer_ptr(&active_state->outgoing_packet),
 709             buffer_len(&active_state->outgoing_packet));
 710
 711 #ifdef PACKET_DEBUG
 712         fprintf(stderr, "encrypted: ");
 713         buffer_dump(&active_state->output);
 714 #endif
 715         active_state->p_send.packets++;
 716         active_state->p_send.bytes += len +
 717             buffer_len(&active_state->outgoing_packet);
 718         buffer_clear(&active_state->outgoing_packet);
 719
 720         /*
 721          * Note that the packet is now only buffered in output.  It won't be
 722          * actually sent until packet_write_wait or packet_write_poll is
 723          * called.
 724          */
 725 }
 726
 727 void
 728 set_newkeys(int mode)
 729 {
 730         Enc *enc;
 731         Mac *mac;
 732         Comp *comp;
 733         CipherContext *cc;
 734         u_int64_t *max_blocks;
 735         int crypt_type;
 736
 737         debug2("set_newkeys: mode %d", mode);
 738
 739         if (mode == MODE_OUT) {
 740                 cc = &active_state->send_context;
 741                 crypt_type = CIPHER_ENCRYPT;
 742                 active_state->p_send.packets = active_state->p_send.blocks = 0;
 743                 max_blocks = &active_state->max_blocks_out;
 744         } else {
 745                 cc = &active_state->receive_context;
 746                 crypt_type = CIPHER_DECRYPT;
 747                 active_state->p_read.packets = active_state->p_read.blocks = 0;
 748                 max_blocks = &active_state->max_blocks_in;
 749         }
 750         if (active_state->newkeys[mode] != NULL) {
 751                 debug("set_newkeys: rekeying");
 752                 cipher_cleanup(cc);
 753                 enc  = &active_state->newkeys[mode]->enc;
 754                 mac  = &active_state->newkeys[mode]->mac;
 755                 comp = &active_state->newkeys[mode]->comp;
 756                 mac_clear(mac);
 757                 xfree(enc->name);
 758                 xfree(enc->iv);
 759                 xfree(enc->key);
 760                 xfree(mac->name);
 761                 xfree(mac->key);
 762                 xfree(comp->name);
 763                 xfree(active_state->newkeys[mode]);
 764         }
 765         active_state->newkeys[mode] = kex_get_newkeys(mode);
 766         if (active_state->newkeys[mode] == NULL)
 767                 fatal("newkeys: no keys for mode %d", mode);
 768         enc  = &active_state->newkeys[mode]->enc;
 769         mac  = &active_state->newkeys[mode]->mac;
 770         comp = &active_state->newkeys[mode]->comp;
 771         if (mac_init(mac) == 0)
 772                 mac->enabled = 1;
 773         DBG(debug("cipher_init_context: %d", mode));
 774         cipher_init(cc, enc->cipher, enc->key, enc->key_len,
 775             enc->iv, enc->block_size, crypt_type);
 776         /* Deleting the keys does not gain extra security */
 777         /* memset(enc->iv,  0, enc->block_size);
 778            memset(enc->key, 0, enc->key_len);
 779            memset(mac->key, 0, mac->key_len); */
 780         if ((comp->type == COMP_ZLIB ||
 781             (comp->type == COMP_DELAYED &&
 782              active_state->after_authentication)) && comp->enabled == 0) {
 783                 packet_init_compression();
 784                 if (mode == MODE_OUT)
 785                         buffer_compress_init_send(6);
 786                 else
 787                         buffer_compress_init_recv();
 788                 comp->enabled = 1;
 789         }
 790         /*
 791          * The 2^(blocksize*2) limit is too expensive for 3DES,
 792          * blowfish, etc, so enforce a 1GB limit for small blocksizes.
 793          */
 794         if (enc->block_size >= 16)
 795                 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
 796         else
 797                 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
 798         if (active_state->rekey_limit)
 799                 *max_blocks = MIN(*max_blocks,
 800                     active_state->rekey_limit / enc->block_size);
 801 }
 802
 803 /*
 804  * Delayed compression for SSH2 is enabled after authentication:
 805  * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
 806  * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
 807  */
 808 static void
 809 packet_enable_delayed_compress(void)
 810 {
 811         Comp *comp = NULL;
 812         int mode;
 813
 814         /*
 815          * Remember that we are past the authentication step, so rekeying
 816          * with COMP_DELAYED will turn on compression immediately.
 817          */
 818         active_state->after_authentication = 1;
 819         for (mode = 0; mode < MODE_MAX; mode++) {
 820                 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
 821                 if (active_state->newkeys[mode] == NULL)
 822                         continue;
 823                 comp = &active_state->newkeys[mode]->comp;
 824                 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
 825                         packet_init_compression();
 826                         if (mode == MODE_OUT)
 827                                 buffer_compress_init_send(6);
 828                         else
 829                                 buffer_compress_init_recv();
 830                         comp->enabled = 1;
 831                 }
 832         }
 833 }
 834
 835 /*
 836  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
 837  */
 838 static int
 839 packet_send2_wrapped(void)
 840 {
 841         u_char type, *cp, *macbuf = NULL;
 842         u_char padlen, pad;
 843         u_int packet_length = 0;
 844         u_int i, len;
 845         u_int32_t rnd = 0;
 846         Enc *enc   = NULL;
 847         Mac *mac   = NULL;
 848         Comp *comp = NULL;
 849         int block_size;
 850
 851         if (active_state->newkeys[MODE_OUT] != NULL) {
 852                 enc  = &active_state->newkeys[MODE_OUT]->enc;
 853                 mac  = &active_state->newkeys[MODE_OUT]->mac;
 854                 comp = &active_state->newkeys[MODE_OUT]->comp;
 855         }
 856         block_size = enc ? enc->block_size : 8;
 857
 858         cp = buffer_ptr(&active_state->outgoing_packet);
 859         type = cp[5];
 860
 861 #ifdef PACKET_DEBUG
 862         fprintf(stderr, "plain:     ");
 863         buffer_dump(&active_state->outgoing_packet);
 864 #endif
 865
 866         if (comp && comp->enabled) {
 867                 len = buffer_len(&active_state->outgoing_packet);
 868                 /* skip header, compress only payload */
 869                 buffer_consume(&active_state->outgoing_packet, 5);
 870                 buffer_clear(&active_state->compression_buffer);
 871                 buffer_compress(&active_state->outgoing_packet,
 872                     &active_state->compression_buffer);
 873                 buffer_clear(&active_state->outgoing_packet);
 874                 buffer_append(&active_state->outgoing_packet, "\0\0\0\0\0", 5);
 875                 buffer_append(&active_state->outgoing_packet,
 876                     buffer_ptr(&active_state->compression_buffer),
 877                     buffer_len(&active_state->compression_buffer));
 878                 DBG(debug("compression: raw %d compressed %d", len,
 879                     buffer_len(&active_state->outgoing_packet)));
 880         }
 881
 882         /* sizeof (packet_len + pad_len + payload) */
 883         len = buffer_len(&active_state->outgoing_packet);
 884
 885         /*
 886          * calc size of padding, alloc space, get random data,
 887          * minimum padding is 4 bytes
 888          */
 889         padlen = block_size - (len % block_size);
 890         if (padlen < 4)
 891                 padlen += block_size;
 892         if (active_state->extra_pad) {
 893                 /* will wrap if extra_pad+padlen > 255 */
 894                 active_state->extra_pad =
 895                     roundup(active_state->extra_pad, block_size);
 896                 pad = active_state->extra_pad -
 897                     ((len + padlen) % active_state->extra_pad);
 898                 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
 899                     pad, len, padlen, active_state->extra_pad);
 900                 padlen += pad;
 901                 active_state->extra_pad = 0;
 902         }
 903         cp = buffer_append_space(&active_state->outgoing_packet, padlen);
 904         if (enc && !active_state->send_context.plaintext) {
 905                 /* random padding */
 906                 for (i = 0; i < padlen; i++) {
 907                         if (i % 4 == 0)
 908                                 rnd = arc4random();
 909                         cp[i] = rnd & 0xff;
 910                         rnd >>= 8;
 911                 }
 912         } else {
 913                 /* clear padding */
 914                 memset(cp, 0, padlen);
 915         }
 916         /* packet_length includes payload, padding and padding length field */
 917         packet_length = buffer_len(&active_state->outgoing_packet) - 4;
 918         cp = buffer_ptr(&active_state->outgoing_packet);
 919         put_u32(cp, packet_length);
 920         cp[4] = padlen;
 921         DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
 922
 923         /* compute MAC over seqnr and packet(length fields, payload, padding) */
 924         if (mac && mac->enabled) {
 925                 macbuf = mac_compute(mac, active_state->p_send.seqnr,
 926                     buffer_ptr(&active_state->outgoing_packet),
 927                     buffer_len(&active_state->outgoing_packet));
 928                 DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
 929         }
 930         /* encrypt packet and append to output buffer. */
 931         cp = buffer_append_space(&active_state->output,
 932             buffer_len(&active_state->outgoing_packet));
 933         cipher_crypt(&active_state->send_context, cp,
 934             buffer_ptr(&active_state->outgoing_packet),
 935             buffer_len(&active_state->outgoing_packet));
 936         /* append unencrypted MAC */
 937         if (mac && mac->enabled)
 938                 buffer_append(&active_state->output, macbuf, mac->mac_len);
 939 #ifdef PACKET_DEBUG
 940         fprintf(stderr, "encrypted: ");
 941         buffer_dump(&active_state->output);
 942 #endif
 943         /* increment sequence number for outgoing packets */
 944         if (++active_state->p_send.seqnr == 0)
 945                 logit("outgoing seqnr wraps around");
 946         if (++active_state->p_send.packets == 0)
 947                 if (!(datafellows & SSH_BUG_NOREKEY))
 948                         fatal("XXX too many packets with same key");
 949         active_state->p_send.blocks += (packet_length + 4) / block_size;
 950         active_state->p_send.bytes += packet_length + 4;
 951         buffer_clear(&active_state->outgoing_packet);
 952
 953         if (type == SSH2_MSG_NEWKEYS)
 954                 set_newkeys(MODE_OUT);
 955         else if (type == SSH2_MSG_USERAUTH_SUCCESS && active_state->server_side)
 956                 packet_enable_delayed_compress();
 957         return(packet_length);
 958 }
 959
 960 static int
 961 packet_send2(void)
 962 {
 963         static int packet_length = 0;
 964         struct packet *p;
 965         u_char type, *cp;
 966
 967         cp = buffer_ptr(&active_state->outgoing_packet);
 968         type = cp[5];
 969
 970         /* during rekeying we can only send key exchange messages */
 971         if (active_state->rekeying) {
 972                 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
 973                     (type <= SSH2_MSG_TRANSPORT_MAX))) {
 974                         debug("enqueue packet: %u", type);
 975                         p = xmalloc(sizeof(*p));
 976                         p->type = type;
 977                         memcpy(&p->payload, &active_state->outgoing_packet,
 978                             sizeof(Buffer));
 979                         buffer_init(&active_state->outgoing_packet);
 980                         TAILQ_INSERT_TAIL(&active_state->outgoing, p, next);
 981                         return(sizeof(Buffer));
 982                 }
 983         }
 984
 985         /* rekeying starts with sending KEXINIT */
 986         if (type == SSH2_MSG_KEXINIT)
 987                 active_state->rekeying = 1;
 988
 989         packet_length = packet_send2_wrapped();
 990
 991         /* after a NEWKEYS message we can send the complete queue */
 992         if (type == SSH2_MSG_NEWKEYS) {
 993                 active_state->rekeying = 0;
 994                 while ((p = TAILQ_FIRST(&active_state->outgoing))) {
 995                         type = p->type;
 996                         debug("dequeue packet: %u", type);
 997                         buffer_free(&active_state->outgoing_packet);
 998                         memcpy(&active_state->outgoing_packet, &p->payload,
 999                             sizeof(Buffer));
1000                         TAILQ_REMOVE(&active_state->outgoing, p, next);
1001                         xfree(p);
1002                         packet_length += packet_send2_wrapped();
1003                 }
1004         }
1005         return(packet_length);
1006 }
1007
1008 int
1009 packet_send(void)
1010 {
1011   int packet_len = 0;
1012         if (compat20)
1013                 packet_len = packet_send2();
1014         else
1015                 packet_send1();
1016         DBG(debug("packet_send done"));
1017         return(packet_len);
1018 }
1019
1020 /*
1021  * Waits until a packet has been received, and returns its type.  Note that
1022  * no other data is processed until this returns, so this function should not
1023  * be used during the interactive session.
1024  */
1025
1026 int
1027 packet_read_seqnr(u_int32_t *seqnr_p)
1028 {
1029         int type, len, ret, ms_remain, cont;
1030         fd_set *setp;
1031         char buf[8192];
1032         struct timeval timeout, start, *timeoutp = NULL;
1033
1034         DBG(debug("packet_read()"));
1035
1036         setp = (fd_set *)xcalloc(howmany(active_state->connection_in + 1,
1037             NFDBITS), sizeof(fd_mask));
1038
1039         /* Since we are blocking, ensure that all written packets have been sent. */
1040         packet_write_wait();
1041
1042         /* Stay in the loop until we have received a complete packet. */
1043         for (;;) {
1044                 /* Try to read a packet from the buffer. */
1045                 type = packet_read_poll_seqnr(seqnr_p);
1046                 if (!compat20 && (
1047                     type == SSH_SMSG_SUCCESS
1048                     || type == SSH_SMSG_FAILURE
1049                     || type == SSH_CMSG_EOF
1050                     || type == SSH_CMSG_EXIT_CONFIRMATION))
1051                         packet_check_eom();
1052                 /* If we got a packet, return it. */
1053                 if (type != SSH_MSG_NONE) {
1054                         xfree(setp);
1055                         return type;
1056                 }
1057                 /*
1058                  * Otherwise, wait for some data to arrive, add it to the
1059                  * buffer, and try again.
1060                  */
1061                 memset(setp, 0, howmany(active_state->connection_in + 1,
1062                     NFDBITS) * sizeof(fd_mask));
1063                 FD_SET(active_state->connection_in, setp);
1064
1065                 if (active_state->packet_timeout_ms > 0) {
1066                         ms_remain = active_state->packet_timeout_ms;
1067                         timeoutp = &timeout;
1068                 }
1069                 /* Wait for some data to arrive. */
1070                 for (;;) {
1071                         if (active_state->packet_timeout_ms != -1) {
1072                                 ms_to_timeval(&timeout, ms_remain);
1073                                 gettimeofday(&start, NULL);
1074                         }
1075                         if ((ret = select(active_state->connection_in + 1, setp,
1076                             NULL, NULL, timeoutp)) >= 0)
1077                                 break;
1078                         if (errno != EAGAIN && errno != EINTR &&
1079                             errno != EWOULDBLOCK)
1080                                 break;
1081                         if (active_state->packet_timeout_ms == -1)
1082                                 continue;
1083                         ms_subtract_diff(&start, &ms_remain);
1084                         if (ms_remain <= 0) {
1085                                 ret = 0;
1086                                 break;
1087                         }
1088                 }
1089                 if (ret == 0) {
1090                         logit("Connection to %.200s timed out while "
1091                             "waiting to read", get_remote_ipaddr());
1092                         cleanup_exit(255);
1093                 }
1094                 /* Read data from the socket. */
1095                 do {
1096                         cont = 0;
1097                         len = roaming_read(active_state->connection_in, buf,
1098                             sizeof(buf), &cont);
1099                 } while (len == 0 && cont);
1100                 if (len == 0) {
1101                         logit("Connection closed by %.200s", get_remote_ipaddr());
1102                         cleanup_exit(255);
1103                 }
1104                 if (len < 0)
1105                         fatal("Read from socket failed: %.100s", strerror(errno));
1106                 /* Append it to the buffer. */
1107                 packet_process_incoming(buf, len);
1108         }
1109         /* NOTREACHED */
1110 }
1111
1112 int
1113 packet_read(void)
1114 {
1115         return packet_read_seqnr(NULL);
1116 }
1117
1118 /*
1119  * Waits until a packet has been received, verifies that its type matches
1120  * that given, and gives a fatal error and exits if there is a mismatch.
1121  */
1122
1123 void
1124 packet_read_expect(int expected_type)
1125 {
1126         int type;
1127
1128         type = packet_read();
1129         if (type != expected_type)
1130                 packet_disconnect("Protocol error: expected packet type %d, got %d",
1131                     expected_type, type);
1132 }
1133
1134 /* Checks if a full packet is available in the data received so far via
1135  * packet_process_incoming.  If so, reads the packet; otherwise returns
1136  * SSH_MSG_NONE.  This does not wait for data from the connection.
1137  *
1138  * SSH_MSG_DISCONNECT is handled specially here.  Also,
1139  * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1140  * to higher levels.
1141  */
1142
1143 static int
1144 packet_read_poll1(void)
1145 {
1146         u_int len, padded_len;
1147         u_char *cp, type;
1148         u_int checksum, stored_checksum;
1149
1150         /* Check if input size is less than minimum packet size. */
1151         if (buffer_len(&active_state->input) < 4 + 8)
1152                 return SSH_MSG_NONE;
1153         /* Get length of incoming packet. */
1154         cp = buffer_ptr(&active_state->input);
1155         len = get_u32(cp);
1156         if (len < 1 + 2 + 2 || len > 256 * 1024)
1157                 packet_disconnect("Bad packet length %u.", len);
1158         padded_len = (len + 8) & ~7;
1159
1160         /* Check if the packet has been entirely received. */
1161         if (buffer_len(&active_state->input) < 4 + padded_len)
1162                 return SSH_MSG_NONE;
1163
1164         /* The entire packet is in buffer. */
1165
1166         /* Consume packet length. */
1167         buffer_consume(&active_state->input, 4);
1168
1169         /*
1170          * Cryptographic attack detector for ssh
1171          * (C)1998 CORE-SDI, Buenos Aires Argentina
1172          * Ariel Futoransky(futo@core-sdi.com)
1173          */
1174         if (!active_state->receive_context.plaintext) {
1175                 switch (detect_attack(buffer_ptr(&active_state->input),
1176                     padded_len)) {
1177                 case DEATTACK_DETECTED:
1178                         packet_disconnect("crc32 compensation attack: "
1179                             "network attack detected");
1180                 case DEATTACK_DOS_DETECTED:
1181                         packet_disconnect("deattack denial of "
1182                             "service detected");
1183                 }
1184         }
1185
1186         /* Decrypt data to incoming_packet. */
1187         buffer_clear(&active_state->incoming_packet);
1188         cp = buffer_append_space(&active_state->incoming_packet, padded_len);
1189         cipher_crypt(&active_state->receive_context, cp,
1190             buffer_ptr(&active_state->input), padded_len);
1191
1192         buffer_consume(&active_state->input, padded_len);
1193
1194 #ifdef PACKET_DEBUG
1195         fprintf(stderr, "read_poll plain: ");
1196         buffer_dump(&active_state->incoming_packet);
1197 #endif
1198
1199         /* Compute packet checksum. */
1200         checksum = ssh_crc32(buffer_ptr(&active_state->incoming_packet),
1201             buffer_len(&active_state->incoming_packet) - 4);
1202
1203         /* Skip padding. */
1204         buffer_consume(&active_state->incoming_packet, 8 - len % 8);
1205
1206         /* Test check bytes. */
1207         if (len != buffer_len(&active_state->incoming_packet))
1208                 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1209                     len, buffer_len(&active_state->incoming_packet));
1210
1211         cp = (u_char *)buffer_ptr(&active_state->incoming_packet) + len - 4;
1212         stored_checksum = get_u32(cp);
1213         if (checksum != stored_checksum)
1214                 packet_disconnect("Corrupted check bytes on input.");
1215         buffer_consume_end(&active_state->incoming_packet, 4);
1216
1217         if (active_state->packet_compression) {
1218                 buffer_clear(&active_state->compression_buffer);
1219                 buffer_uncompress(&active_state->incoming_packet,
1220                     &active_state->compression_buffer);
1221                 buffer_clear(&active_state->incoming_packet);
1222                 buffer_append(&active_state->incoming_packet,
1223                     buffer_ptr(&active_state->compression_buffer),
1224                     buffer_len(&active_state->compression_buffer));
1225         }
1226         active_state->p_read.packets++;
1227         active_state->p_read.bytes += padded_len + 4;
1228         type = buffer_get_char(&active_state->incoming_packet);
1229         if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1230                 packet_disconnect("Invalid ssh1 packet type: %d", type);
1231         return type;
1232 }
1233
1234 static int
1235 packet_read_poll2(u_int32_t *seqnr_p)
1236 {
1237         u_int padlen, need;
1238         u_char *macbuf, *cp, type;
1239         u_int maclen, block_size;
1240         Enc *enc   = NULL;
1241         Mac *mac   = NULL;
1242         Comp *comp = NULL;
1243
1244         if (active_state->packet_discard)
1245                 return SSH_MSG_NONE;
1246
1247         if (active_state->newkeys[MODE_IN] != NULL) {
1248                 enc  = &active_state->newkeys[MODE_IN]->enc;
1249                 mac  = &active_state->newkeys[MODE_IN]->mac;
1250                 comp = &active_state->newkeys[MODE_IN]->comp;
1251         }
1252         maclen = mac && mac->enabled ? mac->mac_len : 0;
1253         block_size = enc ? enc->block_size : 8;
1254
1255         if (active_state->packlen == 0) {
1256                 /*
1257                  * check if input size is less than the cipher block size,
1258                  * decrypt first block and extract length of incoming packet
1259                  */
1260                 if (buffer_len(&active_state->input) < block_size)
1261                         return SSH_MSG_NONE;
1262                 buffer_clear(&active_state->incoming_packet);
1263                 cp = buffer_append_space(&active_state->incoming_packet,
1264                     block_size);
1265                 cipher_crypt(&active_state->receive_context, cp,
1266                     buffer_ptr(&active_state->input), block_size);
1267                 cp = buffer_ptr(&active_state->incoming_packet);
1268                 active_state->packlen = get_u32(cp);
1269                 if (active_state->packlen < 1 + 4 ||
1270                     active_state->packlen > PACKET_MAX_SIZE) {
1271 #ifdef PACKET_DEBUG
1272                         buffer_dump(&active_state->incoming_packet);
1273 #endif
1274                         logit("Bad packet length %u.", active_state->packlen);
1275                         packet_start_discard(enc, mac, active_state->packlen,
1276                             PACKET_MAX_SIZE);
1277                         return SSH_MSG_NONE;
1278                 }
1279                 DBG(debug("input: packet len %u", active_state->packlen+4));
1280                 buffer_consume(&active_state->input, block_size);
1281         }
1282         /* we have a partial packet of block_size bytes */
1283         need = 4 + active_state->packlen - block_size;
1284         DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1285             need, maclen));
1286         if (need % block_size != 0) {
1287                 logit("padding error: need %d block %d mod %d",
1288                     need, block_size, need % block_size);
1289                 packet_start_discard(enc, mac, active_state->packlen,
1290                     PACKET_MAX_SIZE - block_size);
1291                 return SSH_MSG_NONE;
1292         }
1293         /*
1294          * check if the entire packet has been received and
1295          * decrypt into incoming_packet
1296          */
1297         if (buffer_len(&active_state->input) < need + maclen)
1298                 return SSH_MSG_NONE;
1299 #ifdef PACKET_DEBUG
1300         fprintf(stderr, "read_poll enc/full: ");
1301         buffer_dump(&active_state->input);
1302 #endif
1303         cp = buffer_append_space(&active_state->incoming_packet, need);
1304         cipher_crypt(&active_state->receive_context, cp,
1305             buffer_ptr(&active_state->input), need);
1306         buffer_consume(&active_state->input, need);
1307         /*
1308          * compute MAC over seqnr and packet,
1309          * increment sequence number for incoming packet
1310          */
1311         if (mac && mac->enabled) {
1312                 macbuf = mac_compute(mac, active_state->p_read.seqnr,
1313                     buffer_ptr(&active_state->incoming_packet),
1314                     buffer_len(&active_state->incoming_packet));
1315                 if (memcmp(macbuf, buffer_ptr(&active_state->input),
1316                     mac->mac_len) != 0) {
1317                         logit("Corrupted MAC on input.");
1318                         if (need > PACKET_MAX_SIZE)
1319                                 fatal("internal error need %d", need);
1320                         packet_start_discard(enc, mac, active_state->packlen,
1321                             PACKET_MAX_SIZE - need);
1322                         return SSH_MSG_NONE;
1323                 }
1324
1325                 DBG(debug("MAC #%d ok", active_state->p_read.seqnr));
1326                 buffer_consume(&active_state->input, mac->mac_len);
1327         }
1328         /* XXX now it's safe to use fatal/packet_disconnect */
1329         if (seqnr_p != NULL)
1330                 *seqnr_p = active_state->p_read.seqnr;
1331         if (++active_state->p_read.seqnr == 0)
1332                 logit("incoming seqnr wraps around");
1333         if (++active_state->p_read.packets == 0)
1334                 if (!(datafellows & SSH_BUG_NOREKEY))
1335                         fatal("XXX too many packets with same key");
1336         active_state->p_read.blocks += (active_state->packlen + 4) / block_size;
1337         active_state->p_read.bytes += active_state->packlen + 4;
1338
1339         /* get padlen */
1340         cp = buffer_ptr(&active_state->incoming_packet);
1341         padlen = cp[4];
1342         DBG(debug("input: padlen %d", padlen));
1343         if (padlen < 4)
1344                 packet_disconnect("Corrupted padlen %d on input.", padlen);
1345
1346         /* skip packet size + padlen, discard padding */
1347         buffer_consume(&active_state->incoming_packet, 4 + 1);
1348         buffer_consume_end(&active_state->incoming_packet, padlen);
1349
1350         DBG(debug("input: len before de-compress %d",
1351             buffer_len(&active_state->incoming_packet)));
1352         if (comp && comp->enabled) {
1353                 buffer_clear(&active_state->compression_buffer);
1354                 buffer_uncompress(&active_state->incoming_packet,
1355                     &active_state->compression_buffer);
1356                 buffer_clear(&active_state->incoming_packet);
1357                 buffer_append(&active_state->incoming_packet,
1358                     buffer_ptr(&active_state->compression_buffer),
1359                     buffer_len(&active_state->compression_buffer));
1360                 DBG(debug("input: len after de-compress %d",
1361                     buffer_len(&active_state->incoming_packet)));
1362         }
1363         /*
1364          * get packet type, implies consume.
1365          * return length of payload (without type field)
1366          */
1367         type = buffer_get_char(&active_state->incoming_packet);
1368         if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1369                 packet_disconnect("Invalid ssh2 packet type: %d", type);
1370         if (type == SSH2_MSG_NEWKEYS)
1371                 set_newkeys(MODE_IN);
1372         else if (type == SSH2_MSG_USERAUTH_SUCCESS &&
1373             !active_state->server_side)
1374                 packet_enable_delayed_compress();
1375 #ifdef PACKET_DEBUG
1376         fprintf(stderr, "read/plain[%d]:\r\n", type);
1377         buffer_dump(&active_state->incoming_packet);
1378 #endif
1379         /* reset for next packet */
1380         active_state->packlen = 0;
1381         return type;
1382 }
1383
1384 int
1385 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1386 {
1387         u_int reason, seqnr;
1388         u_char type;
1389         char *msg;
1390
1391         for (;;) {
1392                 if (compat20) {
1393                         type = packet_read_poll2(seqnr_p);
1394                         if (type) {
1395                                 active_state->keep_alive_timeouts = 0;
1396                                 DBG(debug("received packet type %d", type));
1397                         }
1398                         switch (type) {
1399                         case SSH2_MSG_IGNORE:
1400                                 debug3("Received SSH2_MSG_IGNORE");
1401                                 break;
1402                         case SSH2_MSG_DEBUG:
1403                                 packet_get_char();
1404                                 msg = packet_get_string(NULL);
1405                                 debug("Remote: %.900s", msg);
1406                                 xfree(msg);
1407                                 msg = packet_get_string(NULL);
1408                                 xfree(msg);
1409                                 break;
1410                         case SSH2_MSG_DISCONNECT:
1411                                 reason = packet_get_int();
1412                                 msg = packet_get_string(NULL);
1413                                 logit("Received disconnect from %s: %u: %.400s",
1414                                     get_remote_ipaddr(), reason, msg);
1415                                 xfree(msg);
1416                                 cleanup_exit(255);
1417                                 break;
1418                         case SSH2_MSG_UNIMPLEMENTED:
1419                                 seqnr = packet_get_int();
1420                                 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1421                                     seqnr);
1422                                 break;
1423                         default:
1424                                 return type;
1425                         }
1426                 } else {
1427                         type = packet_read_poll1();
1428                         switch (type) {
1429                         case SSH_MSG_IGNORE:
1430                                 break;
1431                         case SSH_MSG_DEBUG:
1432                                 msg = packet_get_string(NULL);
1433                                 debug("Remote: %.900s", msg);
1434                                 xfree(msg);
1435                                 break;
1436                         case SSH_MSG_DISCONNECT:
1437                                 msg = packet_get_string(NULL);
1438                                 logit("Received disconnect from %s: %.400s",
1439                                     get_remote_ipaddr(), msg);
1440                                 cleanup_exit(255);
1441                                 break;
1442                         default:
1443                                 if (type)
1444                                         DBG(debug("received packet type %d", type));
1445                                 return type;
1446                         }
1447                 }
1448         }
1449 }
1450
1451 int
1452 packet_read_poll(void)
1453 {
1454         return packet_read_poll_seqnr(NULL);
1455 }
1456
1457 /*
1458  * Buffers the given amount of input characters.  This is intended to be used
1459  * together with packet_read_poll.
1460  */
1461
1462 void
1463 packet_process_incoming(const char *buf, u_int len)
1464 {
1465         if (active_state->packet_discard) {
1466                 active_state->keep_alive_timeouts = 0; /* ?? */
1467                 if (len >= active_state->packet_discard)
1468                         packet_stop_discard();
1469                 active_state->packet_discard -= len;
1470                 return;
1471         }
1472         buffer_append(&active_state->input, buf, len);
1473 }
1474
1475 /* Returns a character from the packet. */
1476
1477 u_int
1478 packet_get_char(void)
1479 {
1480         char ch;
1481
1482         buffer_get(&active_state->incoming_packet, &ch, 1);
1483         return (u_char) ch;
1484 }
1485
1486 /* Returns an integer from the packet data. */
1487
1488 u_int
1489 packet_get_int(void)
1490 {
1491         return buffer_get_int(&active_state->incoming_packet);
1492 }
1493
1494 /* Returns an 64 bit integer from the packet data. */
1495
1496 u_int64_t
1497 packet_get_int64(void)
1498 {
1499         return buffer_get_int64(&active_state->incoming_packet);
1500 }
1501
1502 /*
1503  * Returns an arbitrary precision integer from the packet data.  The integer
1504  * must have been initialized before this call.
1505  */
1506
1507 void
1508 packet_get_bignum(BIGNUM * value)
1509 {
1510         buffer_get_bignum(&active_state->incoming_packet, value);
1511 }
1512
1513 void
1514 packet_get_bignum2(BIGNUM * value)
1515 {
1516         buffer_get_bignum2(&active_state->incoming_packet, value);
1517 }
1518
1519 void *
1520 packet_get_raw(u_int *length_ptr)
1521 {
1522         u_int bytes = buffer_len(&active_state->incoming_packet);
1523
1524         if (length_ptr != NULL)
1525                 *length_ptr = bytes;
1526         return buffer_ptr(&active_state->incoming_packet);
1527 }
1528
1529 int
1530 packet_remaining(void)
1531 {
1532         return buffer_len(&active_state->incoming_packet);
1533 }
1534
1535 /*
1536  * Returns a string from the packet data.  The string is allocated using
1537  * xmalloc; it is the responsibility of the calling program to free it when
1538  * no longer needed.  The length_ptr argument may be NULL, or point to an
1539  * integer into which the length of the string is stored.
1540  */
1541
1542 void *
1543 packet_get_string(u_int *length_ptr)
1544 {
1545         return buffer_get_string(&active_state->incoming_packet, length_ptr);
1546 }
1547
1548 void *
1549 packet_get_string_ptr(u_int *length_ptr)
1550 {
1551         return buffer_get_string_ptr(&active_state->incoming_packet, length_ptr);
1552 }
1553
1554 /*
1555  * Sends a diagnostic message from the server to the client.  This message
1556  * can be sent at any time (but not while constructing another message). The
1557  * message is printed immediately, but only if the client is being executed
1558  * in verbose mode.  These messages are primarily intended to ease debugging
1559  * authentication problems.   The length of the formatted message must not
1560  * exceed 1024 bytes.  This will automatically call packet_write_wait.
1561  */
1562
1563 void
1564 packet_send_debug(const char *fmt,...)
1565 {
1566         char buf[1024];
1567         va_list args;
1568
1569         if (compat20 && (datafellows & SSH_BUG_DEBUG))
1570                 return;
1571
1572         va_start(args, fmt);
1573         vsnprintf(buf, sizeof(buf), fmt, args);
1574         va_end(args);
1575
1576         if (compat20) {
1577                 packet_start(SSH2_MSG_DEBUG);
1578                 packet_put_char(0);     /* bool: always display */
1579                 packet_put_cstring(buf);
1580                 packet_put_cstring("");
1581         } else {
1582                 packet_start(SSH_MSG_DEBUG);
1583                 packet_put_cstring(buf);
1584         }
1585         packet_send();
1586         packet_write_wait();
1587 }
1588
1589 /*
1590  * Logs the error plus constructs and sends a disconnect packet, closes the
1591  * connection, and exits.  This function never returns. The error message
1592  * should not contain a newline.  The length of the formatted message must
1593  * not exceed 1024 bytes.
1594  */
1595
1596 void
1597 packet_disconnect(const char *fmt,...)
1598 {
1599         char buf[1024];
1600         va_list args;
1601         static int disconnecting = 0;
1602
1603         if (disconnecting)      /* Guard against recursive invocations. */
1604                 fatal("packet_disconnect called recursively.");
1605         disconnecting = 1;
1606
1607         /*
1608          * Format the message.  Note that the caller must make sure the
1609          * message is of limited size.
1610          */
1611         va_start(args, fmt);
1612         vsnprintf(buf, sizeof(buf), fmt, args);
1613         va_end(args);
1614
1615         /* Display the error locally */
1616         logit("Disconnecting: %.100s", buf);
1617
1618         /* Send the disconnect message to the other side, and wait for it to get sent. */
1619         if (compat20) {
1620                 packet_start(SSH2_MSG_DISCONNECT);
1621                 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1622                 packet_put_cstring(buf);
1623                 packet_put_cstring("");
1624         } else {
1625                 packet_start(SSH_MSG_DISCONNECT);
1626                 packet_put_cstring(buf);
1627         }
1628         packet_send();
1629         packet_write_wait();
1630
1631         /* Stop listening for connections. */
1632         channel_close_all();
1633
1634         /* Close the connection. */
1635         packet_close();
1636         cleanup_exit(255);
1637 }
1638
1639 /* Checks if there is any buffered output, and tries to write some of the output. */
1640
1641 int
1642 packet_write_poll(void)
1643 {
1644         int len = 0;
1645         int cont;
1646
1647         len = buffer_len(&active_state->output);
1648
1649         if (len > 0) {
1650                 cont = 0;
1651                 len = roaming_write(active_state->connection_out,
1652                     buffer_ptr(&active_state->output), len, &cont);
1653                 if (len == -1) {
1654                         if (errno == EINTR || errno == EAGAIN ||
1655                             errno == EWOULDBLOCK)
1656                                 return (0);
1657                         fatal("Write failed: %.100s", strerror(errno));
1658                 }
1659                 if (len == 0 && !cont)
1660                         fatal("Write connection closed");
1661                 buffer_consume(&active_state->output, len);
1662         }
1663         return(len);
1664 }
1665
1666 /*
1667  * Calls packet_write_poll repeatedly until all pending output data has been
1668  * written.
1669  */
1670
1671 int
1672 packet_write_wait(void)
1673 {
1674         fd_set *setp;
1675         int ret, ms_remain;
1676         struct timeval start, timeout, *timeoutp = NULL;
1677         u_int bytes_sent = 0;
1678
1679         setp = (fd_set *)xcalloc(howmany(active_state->connection_out + 1,
1680             NFDBITS), sizeof(fd_mask));
1681         bytes_sent += packet_write_poll();
1682         while (packet_have_data_to_write()) {
1683                 memset(setp, 0, howmany(active_state->connection_out + 1,
1684                     NFDBITS) * sizeof(fd_mask));
1685                 FD_SET(active_state->connection_out, setp);
1686
1687                 if (active_state->packet_timeout_ms > 0) {
1688                         ms_remain = active_state->packet_timeout_ms;
1689                         timeoutp = &timeout;
1690                 }
1691                 for (;;) {
1692                         if (active_state->packet_timeout_ms != -1) {
1693                                 ms_to_timeval(&timeout, ms_remain);
1694                                 gettimeofday(&start, NULL);
1695                         }
1696                         if ((ret = select(active_state->connection_out + 1,
1697                             NULL, setp, NULL, timeoutp)) >= 0)
1698                                 break;
1699                         if (errno != EAGAIN && errno != EINTR &&
1700                             errno != EWOULDBLOCK)
1701                                 break;
1702                         if (active_state->packet_timeout_ms == -1)
1703                                 continue;
1704                         ms_subtract_diff(&start, &ms_remain);
1705                         if (ms_remain <= 0) {
1706                                 ret = 0;
1707                                 break;
1708                         }
1709                 }
1710                 if (ret == 0) {
1711                         logit("Connection to %.200s timed out while "
1712                             "waiting to write", get_remote_ipaddr());
1713                         cleanup_exit(255);
1714                 }
1715                 bytes_sent += packet_write_poll();
1716         }
1717         xfree(setp);
1718         return (bytes_sent);
1719 }
1720
1721 /* Returns true if there is buffered data to write to the connection. */
1722
1723 int
1724 packet_have_data_to_write(void)
1725 {
1726         return buffer_len(&active_state->output) != 0;
1727 }
1728
1729 /* Returns true if there is not too much data to write to the connection. */
1730
1731 int
1732 packet_not_very_much_data_to_write(void)
1733 {
1734         if (active_state->interactive_mode)
1735                 return buffer_len(&active_state->output) < 16384;
1736         else
1737                 return buffer_len(&active_state->output) < 128 * 1024;
1738 }
1739
1740 static void
1741 packet_set_tos(int interactive)
1742 {
1743 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1744         int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1745
1746         if (!packet_connection_is_on_socket() ||
1747             !packet_connection_is_ipv4())
1748                 return;
1749         if (setsockopt(active_state->connection_in, IPPROTO_IP, IP_TOS, &tos,
1750             sizeof(tos)) < 0)
1751                 error("setsockopt IP_TOS %d: %.100s:",
1752                     tos, strerror(errno));
1753 #endif
1754 }
1755
1756 /* Informs that the current session is interactive.  Sets IP flags for that. */
1757
1758 void
1759 packet_set_interactive(int interactive)
1760 {
1761         if (active_state->set_interactive_called)
1762                 return;
1763         active_state->set_interactive_called = 1;
1764
1765         /* Record that we are in interactive mode. */
1766         active_state->interactive_mode = interactive;
1767
1768         /* Only set socket options if using a socket.  */
1769         if (!packet_connection_is_on_socket())
1770                 return;
1771         set_nodelay(active_state->connection_in);
1772         packet_set_tos(interactive);
1773 }
1774
1775 /* Returns true if the current connection is interactive. */
1776
1777 int
1778 packet_is_interactive(void)
1779 {
1780         return active_state->interactive_mode;
1781 }
1782
1783 int
1784 packet_set_maxsize(u_int s)
1785 {
1786         if (active_state->set_maxsize_called) {
1787                 logit("packet_set_maxsize: called twice: old %d new %d",
1788                     active_state->max_packet_size, s);
1789                 return -1;
1790         }
1791         if (s < 4 * 1024 || s > 1024 * 1024) {
1792                 logit("packet_set_maxsize: bad size %d", s);
1793                 return -1;
1794         }
1795         active_state->set_maxsize_called = 1;
1796         debug("packet_set_maxsize: setting to %d", s);
1797         active_state->max_packet_size = s;
1798         return s;
1799 }
1800
1801 int
1802 packet_inc_alive_timeouts(void)
1803 {
1804         return ++active_state->keep_alive_timeouts;
1805 }
1806
1807 void
1808 packet_set_alive_timeouts(int ka)
1809 {
1810         active_state->keep_alive_timeouts = ka;
1811 }
1812
1813 u_int
1814 packet_get_maxsize(void)
1815 {
1816         return active_state->max_packet_size;
1817 }
1818
1819 /* roundup current message to pad bytes */
1820 void
1821 packet_add_padding(u_char pad)
1822 {
1823         active_state->extra_pad = pad;
1824 }
1825
1826 /*
1827  * 9.2.  Ignored Data Message
1828  *
1829  *   byte      SSH_MSG_IGNORE
1830  *   string    data
1831  *
1832  * All implementations MUST understand (and ignore) this message at any
1833  * time (after receiving the protocol version). No implementation is
1834  * required to send them. This message can be used as an additional
1835  * protection measure against advanced traffic analysis techniques.
1836  */
1837 void
1838 packet_send_ignore(int nbytes)
1839 {
1840         u_int32_t rnd = 0;
1841         int i;
1842
1843         packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1844         packet_put_int(nbytes);
1845         for (i = 0; i < nbytes; i++) {
1846                 if (i % 4 == 0)
1847                         rnd = arc4random();
1848                 packet_put_char((u_char)rnd & 0xff);
1849                 rnd >>= 8;
1850         }
1851 }
1852
1853 int rekey_requested = 0;
1854 void
1855 packet_request_rekeying(void)
1856 {
1857         rekey_requested = 1;
1858 }
1859
1860 #define MAX_PACKETS     (1U<<31)
1861 int
1862 packet_need_rekeying(void)
1863 {
1864         if (datafellows & SSH_BUG_NOREKEY)
1865                 return 0;
1866         if (rekey_requested == 1)
1867         {
1868                 rekey_requested = 0;
1869                 return 1;
1870         }
1871         return
1872             (active_state->p_send.packets > MAX_PACKETS) ||
1873             (active_state->p_read.packets > MAX_PACKETS) ||
1874             (active_state->max_blocks_out &&
1875                 (active_state->p_send.blocks > active_state->max_blocks_out)) ||
1876             (active_state->max_blocks_in &&
1877                 (active_state->p_read.blocks > active_state->max_blocks_in));
1878 }
1879
1880 void
1881 packet_set_rekey_limit(u_int32_t bytes)
1882 {
1883         active_state->rekey_limit = bytes;
1884 }
1885
1886 void
1887 packet_set_server(void)
1888 {
1889         active_state->server_side = 1;
1890 }
1891
1892 void
1893 packet_set_authenticated(void)
1894 {
1895         active_state->after_authentication = 1;
1896 }
1897
1898 void *
1899 packet_get_input(void)
1900 {
1901         return (void *)&active_state->input;
1902 }
1903
1904 void *
1905 packet_get_output(void)
1906 {
1907         return (void *)&active_state->output;
1908 }
1909
1910 void *
1911 packet_get_newkeys(int mode)
1912 {
1913         return (void *)active_state->newkeys[mode];
1914 }
1915
1916 /*
1917  * Save the state for the real connection, and use a separate state when
1918  * resuming a suspended connection.
1919  */
1920 void
1921 packet_backup_state(void)
1922 {
1923         struct session_state *tmp;
1924
1925         close(active_state->connection_in);
1926         active_state->connection_in = -1;
1927         close(active_state->connection_out);
1928         active_state->connection_out = -1;
1929         if (backup_state)
1930                 tmp = backup_state;
1931         else
1932                 tmp = alloc_session_state();
1933         backup_state = active_state;
1934         active_state = tmp;
1935 }
1936
1937 /*
1938  * Swap in the old state when resuming a connecion.
1939  */
1940 void
1941 packet_restore_state(void)
1942 {
1943         struct session_state *tmp;
1944         void *buf;
1945         u_int len;
1946
1947         tmp = backup_state;
1948         backup_state = active_state;
1949         active_state = tmp;
1950         active_state->connection_in = backup_state->connection_in;
1951         backup_state->connection_in = -1;
1952         active_state->connection_out = backup_state->connection_out;
1953         backup_state->connection_out = -1;
1954         len = buffer_len(&backup_state->input);
1955         if (len > 0) {
1956                 buf = buffer_ptr(&backup_state->input);
1957                 buffer_append(&active_state->input, buf, len);
1958                 buffer_clear(&backup_state->input);
1959                 add_recv_bytes(len);
1960         }
1961 }
1962
1963 int
1964 packet_authentication_state(void)
1965 {
1966         return(active_state->after_authentication);
1967 }