Annotation of src/usr.bin/ssh/packet.c, Revision 1.25
1.1 deraadt 1: /*
1.15 deraadt 2: *
3: * packet.c
4: *
5: * Author: Tatu Ylonen <ylo@cs.hut.fi>
6: *
7: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8: * All rights reserved
9: *
10: * Created: Sat Mar 18 02:40:40 1995 ylo
11: *
12: * This file contains code implementing the packet protocol and communication
13: * with the other side. This same code is used both on client and server side.
1.25 ! markus 14: *
! 15: * SSH2 packet format added by Markus Friedl.
! 16: *
1.15 deraadt 17: */
1.1 deraadt 18:
19: #include "includes.h"
1.25 ! markus 20: RCSID("$Id: packet.c,v 1.11 2000/03/31 09:40:42 markus Exp $");
1.1 deraadt 21:
22: #include "xmalloc.h"
23: #include "buffer.h"
24: #include "packet.h"
25: #include "bufaux.h"
26: #include "ssh.h"
27: #include "crc32.h"
28: #include "cipher.h"
29: #include "getput.h"
30:
31: #include "compress.h"
1.9 dugsong 32: #include "deattack.h"
1.23 markus 33: #include "channels.h"
1.1 deraadt 34:
1.25 ! markus 35: #include "compat.h"
! 36: #include "ssh2.h"
! 37:
! 38: #include <ssl/bn.h>
! 39: #include <ssl/dh.h>
! 40: #include <ssl/hmac.h>
! 41: #include "buffer.h"
! 42: #include "kex.h"
! 43: #include "hmac.h"
! 44:
! 45: #ifdef PACKET_DEBUG
! 46: #define DBG(x) x
! 47: #else
! 48: #define DBG(x)
! 49: #endif
! 50:
1.16 markus 51: /*
52: * This variable contains the file descriptors used for communicating with
53: * the other side. connection_in is used for reading; connection_out for
54: * writing. These can be the same descriptor, in which case it is assumed to
55: * be a socket.
56: */
1.1 deraadt 57: static int connection_in = -1;
58: static int connection_out = -1;
59:
1.16 markus 60: /*
61: * Cipher type. This value is only used to determine whether to pad the
62: * packets with zeroes or random data.
63: */
1.1 deraadt 64: static int cipher_type = SSH_CIPHER_NONE;
65:
66: /* Protocol flags for the remote side. */
67: static unsigned int remote_protocol_flags = 0;
68:
69: /* Encryption context for receiving data. This is only used for decryption. */
70: static CipherContext receive_context;
1.14 markus 71:
72: /* Encryption context for sending data. This is only used for encryption. */
1.1 deraadt 73: static CipherContext send_context;
74:
75: /* Buffer for raw input data from the socket. */
76: static Buffer input;
77:
78: /* Buffer for raw output data going to the socket. */
79: static Buffer output;
80:
81: /* Buffer for the partial outgoing packet being constructed. */
82: static Buffer outgoing_packet;
83:
84: /* Buffer for the incoming packet currently being processed. */
85: static Buffer incoming_packet;
86:
87: /* Scratch buffer for packet compression/decompression. */
88: static Buffer compression_buffer;
89:
90: /* Flag indicating whether packet compression/decompression is enabled. */
91: static int packet_compression = 0;
92:
1.12 markus 93: /* default maximum packet size */
94: int max_packet_size = 32768;
95:
1.1 deraadt 96: /* Flag indicating whether this module has been initialized. */
97: static int initialized = 0;
98:
99: /* Set to true if the connection is interactive. */
100: static int interactive_mode = 0;
101:
1.25 ! markus 102: /* True if SSH2 packet format is used */
! 103: int use_ssh2_packet_format = 0;
! 104:
! 105: /* Session key information for Encryption and MAC */
! 106: Kex *kex = NULL;
! 107:
! 108: void
! 109: packet_set_kex(Kex *k)
! 110: {
! 111: if( k->mac[MODE_IN ].key == NULL ||
! 112: k->enc[MODE_IN ].key == NULL ||
! 113: k->enc[MODE_IN ].iv == NULL ||
! 114: k->mac[MODE_OUT].key == NULL ||
! 115: k->enc[MODE_OUT].key == NULL ||
! 116: k->enc[MODE_OUT].iv == NULL)
! 117: fatal("bad KEX");
! 118: kex = k;
! 119: }
! 120: void
! 121: clear_enc_keys(Enc *enc, int len)
! 122: {
! 123: memset(enc->iv, 0, len);
! 124: memset(enc->key, 0, len);
! 125: xfree(enc->iv);
! 126: xfree(enc->key);
! 127: enc->iv = NULL;
! 128: enc->key = NULL;
! 129: }
! 130: void
! 131: packet_set_ssh2_format(void)
! 132: {
! 133: debug("use_ssh2_packet_format");
! 134: use_ssh2_packet_format = 1;
! 135: }
! 136:
1.16 markus 137: /*
138: * Sets the descriptors used for communication. Disables encryption until
139: * packet_set_encryption_key is called.
140: */
1.2 provos 141: void
142: packet_set_connection(int fd_in, int fd_out)
1.1 deraadt 143: {
1.14 markus 144: connection_in = fd_in;
145: connection_out = fd_out;
146: cipher_type = SSH_CIPHER_NONE;
147: cipher_set_key(&send_context, SSH_CIPHER_NONE, (unsigned char *) "", 0, 1);
148: cipher_set_key(&receive_context, SSH_CIPHER_NONE, (unsigned char *) "", 0, 0);
149: if (!initialized) {
150: initialized = 1;
151: buffer_init(&input);
152: buffer_init(&output);
153: buffer_init(&outgoing_packet);
154: buffer_init(&incoming_packet);
155: }
156: /* Kludge: arrange the close function to be called from fatal(). */
157: fatal_add_cleanup((void (*) (void *)) packet_close, NULL);
1.1 deraadt 158: }
159:
1.19 markus 160: /* Returns 1 if remote host is connected via socket, 0 if not. */
161:
162: int
163: packet_connection_is_on_socket()
164: {
165: struct sockaddr_storage from, to;
166: socklen_t fromlen, tolen;
167:
168: /* filedescriptors in and out are the same, so it's a socket */
169: if (connection_in == connection_out)
170: return 1;
171: fromlen = sizeof(from);
172: memset(&from, 0, sizeof(from));
1.20 markus 173: if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
1.19 markus 174: return 0;
175: tolen = sizeof(to);
176: memset(&to, 0, sizeof(to));
1.20 markus 177: if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
1.19 markus 178: return 0;
179: if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
180: return 0;
181: if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
182: return 0;
183: return 1;
184: }
185:
186: /* returns 1 if connection is via ipv4 */
187:
188: int
189: packet_connection_is_ipv4()
190: {
191: struct sockaddr_storage to;
1.21 deraadt 192: socklen_t tolen = sizeof(to);
1.19 markus 193:
194: memset(&to, 0, sizeof(to));
195: if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
196: return 0;
197: if (to.ss_family != AF_INET)
198: return 0;
199: return 1;
200: }
201:
1.1 deraadt 202: /* Sets the connection into non-blocking mode. */
203:
1.2 provos 204: void
205: packet_set_nonblocking()
1.1 deraadt 206: {
1.14 markus 207: /* Set the socket into non-blocking mode. */
208: if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0)
209: error("fcntl O_NONBLOCK: %.100s", strerror(errno));
210:
211: if (connection_out != connection_in) {
212: if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0)
213: error("fcntl O_NONBLOCK: %.100s", strerror(errno));
214: }
1.1 deraadt 215: }
216:
217: /* Returns the socket used for reading. */
218:
1.2 provos 219: int
220: packet_get_connection_in()
1.1 deraadt 221: {
1.14 markus 222: return connection_in;
1.1 deraadt 223: }
224:
225: /* Returns the descriptor used for writing. */
226:
1.2 provos 227: int
228: packet_get_connection_out()
1.1 deraadt 229: {
1.14 markus 230: return connection_out;
1.1 deraadt 231: }
232:
233: /* Closes the connection and clears and frees internal data structures. */
234:
1.2 provos 235: void
236: packet_close()
1.1 deraadt 237: {
1.14 markus 238: if (!initialized)
239: return;
240: initialized = 0;
241: if (connection_in == connection_out) {
242: shutdown(connection_out, SHUT_RDWR);
243: close(connection_out);
244: } else {
245: close(connection_in);
246: close(connection_out);
247: }
248: buffer_free(&input);
249: buffer_free(&output);
250: buffer_free(&outgoing_packet);
251: buffer_free(&incoming_packet);
252: if (packet_compression) {
253: buffer_free(&compression_buffer);
254: buffer_compress_uninit();
255: }
1.1 deraadt 256: }
257:
258: /* Sets remote side protocol flags. */
259:
1.2 provos 260: void
261: packet_set_protocol_flags(unsigned int protocol_flags)
1.1 deraadt 262: {
1.14 markus 263: remote_protocol_flags = protocol_flags;
264: channel_set_options((protocol_flags & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) != 0);
1.1 deraadt 265: }
266:
267: /* Returns the remote protocol flags set earlier by the above function. */
268:
1.2 provos 269: unsigned int
270: packet_get_protocol_flags()
1.1 deraadt 271: {
1.14 markus 272: return remote_protocol_flags;
1.1 deraadt 273: }
274:
1.16 markus 275: /*
276: * Starts packet compression from the next packet on in both directions.
277: * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
278: */
1.1 deraadt 279:
1.25 ! markus 280: /*** XXXXX todo: kex means re-init */
1.2 provos 281: void
282: packet_start_compression(int level)
1.1 deraadt 283: {
1.14 markus 284: if (packet_compression)
285: fatal("Compression already enabled.");
286: packet_compression = 1;
287: buffer_init(&compression_buffer);
288: buffer_compress_init(level);
1.1 deraadt 289: }
290:
1.16 markus 291: /*
292: * Encrypts the given number of bytes, copying from src to dest. bytes is
293: * known to be a multiple of 8.
294: */
1.1 deraadt 295:
1.2 provos 296: void
1.14 markus 297: packet_encrypt(CipherContext * cc, void *dest, void *src,
1.25 ! markus 298: unsigned int bytes)
1.1 deraadt 299: {
1.14 markus 300: cipher_encrypt(cc, dest, src, bytes);
1.1 deraadt 301: }
302:
1.16 markus 303: /*
304: * Decrypts the given number of bytes, copying from src to dest. bytes is
305: * known to be a multiple of 8.
306: */
1.1 deraadt 307:
1.2 provos 308: void
1.14 markus 309: packet_decrypt(CipherContext * cc, void *dest, void *src,
1.25 ! markus 310: unsigned int bytes)
1.1 deraadt 311: {
1.14 markus 312: int i;
313:
314: if ((bytes % 8) != 0)
315: fatal("packet_decrypt: bad ciphertext length %d", bytes);
316:
1.16 markus 317: /*
318: * Cryptographic attack detector for ssh - Modifications for packet.c
319: * (C)1998 CORE-SDI, Buenos Aires Argentina Ariel Futoransky(futo@core-sdi.com)
320: */
1.14 markus 321:
1.25 ! markus 322: if (cc->type == SSH_CIPHER_NONE || compat20) {
1.14 markus 323: i = DEATTACK_OK;
1.25 ! markus 324: } else {
1.14 markus 325: i = detect_attack(src, bytes, NULL);
326: }
327: if (i == DEATTACK_DETECTED)
328: packet_disconnect("crc32 compensation attack: network attack detected");
329:
330: cipher_decrypt(cc, dest, src, bytes);
1.1 deraadt 331: }
332:
1.16 markus 333: /*
334: * Causes any further packets to be encrypted using the given key. The same
335: * key is used for both sending and reception. However, both directions are
336: * encrypted independently of each other.
337: */
1.1 deraadt 338:
1.2 provos 339: void
340: packet_set_encryption_key(const unsigned char *key, unsigned int keylen,
1.25 ! markus 341: int cipher)
1.1 deraadt 342: {
1.25 ! markus 343: if (keylen < 20)
! 344: fatal("keylen too small: %d", keylen);
! 345:
1.14 markus 346: /* All other ciphers use the same key in both directions for now. */
347: cipher_set_key(&receive_context, cipher, key, keylen, 0);
348: cipher_set_key(&send_context, cipher, key, keylen, 1);
1.1 deraadt 349: }
350:
351: /* Starts constructing a packet to send. */
352:
1.2 provos 353: void
1.25 ! markus 354: packet_start1(int type)
1.1 deraadt 355: {
1.14 markus 356: char buf[9];
1.1 deraadt 357:
1.14 markus 358: buffer_clear(&outgoing_packet);
359: memset(buf, 0, 8);
360: buf[8] = type;
361: buffer_append(&outgoing_packet, buf, 9);
1.1 deraadt 362: }
363:
1.25 ! markus 364: void
! 365: packet_start2(int type)
! 366: {
! 367: char buf[4+1+1];
! 368:
! 369: buffer_clear(&outgoing_packet);
! 370: memset(buf, 0, sizeof buf);
! 371: /* buf[0..3] = payload_len; */
! 372: /* buf[4] = pad_len; */
! 373: buf[5] = type & 0xff;
! 374: buffer_append(&outgoing_packet, buf, sizeof buf);
! 375: }
! 376:
! 377: void
! 378: packet_start(int type)
! 379: {
! 380: DBG(debug("packet_start[%d]",type));
! 381: if (use_ssh2_packet_format)
! 382: packet_start2(type);
! 383: else
! 384: packet_start1(type);
! 385: }
! 386:
1.1 deraadt 387: /* Appends a character to the packet data. */
388:
1.2 provos 389: void
390: packet_put_char(int value)
1.1 deraadt 391: {
1.14 markus 392: char ch = value;
393: buffer_append(&outgoing_packet, &ch, 1);
1.1 deraadt 394: }
395:
396: /* Appends an integer to the packet data. */
397:
1.2 provos 398: void
399: packet_put_int(unsigned int value)
1.1 deraadt 400: {
1.14 markus 401: buffer_put_int(&outgoing_packet, value);
1.1 deraadt 402: }
403:
404: /* Appends a string to packet data. */
405:
1.2 provos 406: void
407: packet_put_string(const char *buf, unsigned int len)
1.1 deraadt 408: {
1.14 markus 409: buffer_put_string(&outgoing_packet, buf, len);
1.1 deraadt 410: }
1.24 markus 411: void
412: packet_put_cstring(const char *str)
413: {
414: buffer_put_string(&outgoing_packet, str, strlen(str));
415: }
416:
417: void
418: packet_put_raw(const char *buf, unsigned int len)
419: {
420: buffer_append(&outgoing_packet, buf, len);
421: }
422:
1.1 deraadt 423:
424: /* Appends an arbitrary precision integer to packet data. */
425:
1.2 provos 426: void
1.14 markus 427: packet_put_bignum(BIGNUM * value)
1.1 deraadt 428: {
1.14 markus 429: buffer_put_bignum(&outgoing_packet, value);
1.1 deraadt 430: }
1.24 markus 431: void
432: packet_put_bignum2(BIGNUM * value)
433: {
434: buffer_put_bignum2(&outgoing_packet, value);
435: }
1.1 deraadt 436:
1.16 markus 437: /*
438: * Finalizes and sends the packet. If the encryption key has been set,
439: * encrypts the packet before sending.
440: */
1.14 markus 441:
1.2 provos 442: void
1.25 ! markus 443: packet_send1()
1.1 deraadt 444: {
1.14 markus 445: char buf[8], *cp;
446: int i, padding, len;
447: unsigned int checksum;
448: u_int32_t rand = 0;
449:
1.16 markus 450: /*
451: * If using packet compression, compress the payload of the outgoing
452: * packet.
453: */
1.14 markus 454: if (packet_compression) {
455: buffer_clear(&compression_buffer);
456: /* Skip padding. */
457: buffer_consume(&outgoing_packet, 8);
458: /* padding */
459: buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
460: buffer_compress(&outgoing_packet, &compression_buffer);
461: buffer_clear(&outgoing_packet);
462: buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
463: buffer_len(&compression_buffer));
464: }
465: /* Compute packet length without padding (add checksum, remove padding). */
466: len = buffer_len(&outgoing_packet) + 4 - 8;
467:
468: /* Insert padding. */
469: padding = 8 - len % 8;
470: if (cipher_type != SSH_CIPHER_NONE) {
471: cp = buffer_ptr(&outgoing_packet);
472: for (i = 0; i < padding; i++) {
473: if (i % 4 == 0)
474: rand = arc4random();
475: cp[7 - i] = rand & 0xff;
476: rand >>= 8;
477: }
478: }
479: buffer_consume(&outgoing_packet, 8 - padding);
480:
481: /* Add check bytes. */
482: checksum = crc32((unsigned char *) buffer_ptr(&outgoing_packet),
483: buffer_len(&outgoing_packet));
484: PUT_32BIT(buf, checksum);
485: buffer_append(&outgoing_packet, buf, 4);
1.1 deraadt 486:
487: #ifdef PACKET_DEBUG
1.14 markus 488: fprintf(stderr, "packet_send plain: ");
489: buffer_dump(&outgoing_packet);
1.1 deraadt 490: #endif
491:
1.14 markus 492: /* Append to output. */
493: PUT_32BIT(buf, len);
494: buffer_append(&output, buf, 4);
495: buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
496: packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
497: buffer_len(&outgoing_packet));
498:
1.1 deraadt 499: #ifdef PACKET_DEBUG
1.14 markus 500: fprintf(stderr, "encrypted: ");
501: buffer_dump(&output);
1.1 deraadt 502: #endif
503:
1.14 markus 504: buffer_clear(&outgoing_packet);
1.1 deraadt 505:
1.16 markus 506: /*
507: * Note that the packet is now only buffered in output. It won\'t be
508: * actually sent until packet_write_wait or packet_write_poll is
509: * called.
510: */
1.1 deraadt 511: }
512:
1.16 markus 513: /*
1.25 ! markus 514: * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
! 515: */
! 516: void
! 517: packet_send2()
! 518: {
! 519: unsigned char *macbuf = NULL;
! 520: char *cp;
! 521: unsigned int packet_length = 0;
! 522: unsigned int i, padlen, len;
! 523: u_int32_t rand = 0;
! 524: static unsigned int seqnr = 0;
! 525: int type;
! 526: Enc *enc = NULL;
! 527: Mac *mac = NULL;
! 528: Comp *comp = NULL;
! 529: int block_size;
! 530:
! 531: if (kex != NULL) {
! 532: enc = &kex->enc[MODE_OUT];
! 533: mac = &kex->mac[MODE_OUT];
! 534: comp = &kex->comp[MODE_OUT];
! 535: }
! 536: block_size = enc ? enc->block_size : 8;
! 537:
! 538: cp = buffer_ptr(&outgoing_packet);
! 539: type = cp[5] & 0xff;
! 540:
! 541: #ifdef PACKET_DEBUG
! 542: fprintf(stderr, "plain: ");
! 543: buffer_dump(&outgoing_packet);
! 544: #endif
! 545:
! 546: if (comp && comp->enabled) {
! 547: len = buffer_len(&outgoing_packet);
! 548: /* skip header, compress only payload */
! 549: buffer_consume(&outgoing_packet, 5);
! 550: buffer_clear(&compression_buffer);
! 551: buffer_compress(&outgoing_packet, &compression_buffer);
! 552: buffer_clear(&outgoing_packet);
! 553: buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
! 554: buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
! 555: buffer_len(&compression_buffer));
! 556: DBG(debug("compression: raw %d compressed %d", len,
! 557: buffer_len(&outgoing_packet)));
! 558: }
! 559:
! 560: /* sizeof (packet_len + pad_len + payload) */
! 561: len = buffer_len(&outgoing_packet);
! 562:
! 563: /*
! 564: * calc size of padding, alloc space, get random data,
! 565: * minimum padding is 4 bytes
! 566: */
! 567: padlen = block_size - (len % block_size);
! 568: if (padlen < 4)
! 569: padlen += block_size;
! 570: buffer_append_space(&outgoing_packet, &cp, padlen);
! 571: if (enc && enc->type != SSH_CIPHER_NONE) {
! 572: for (i = 0; i < padlen; i++) {
! 573: if (i % 4 == 0)
! 574: rand = arc4random();
! 575: cp[i] = rand & 0xff;
! 576: rand <<= 8;
! 577: }
! 578: }
! 579: /* packet_length includes payload, padding and padding length field */
! 580: packet_length = buffer_len(&outgoing_packet) - 4;
! 581: cp = buffer_ptr(&outgoing_packet);
! 582: PUT_32BIT(cp, packet_length);
! 583: cp[4] = padlen & 0xff;
! 584: DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
! 585:
! 586: /* compute MAC over seqnr and packet(length fields, payload, padding) */
! 587: if (mac && mac->enabled) {
! 588: macbuf = hmac( mac->md, seqnr,
! 589: (unsigned char *) buffer_ptr(&outgoing_packet),
! 590: buffer_len(&outgoing_packet),
! 591: mac->key, mac->key_len
! 592: );
! 593: DBG(debug("done calc HMAC out #%d", seqnr));
! 594: }
! 595: /* encrypt packet and append to output buffer. */
! 596: buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
! 597: packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
! 598: buffer_len(&outgoing_packet));
! 599: /* append unencrypted MAC */
! 600: if (mac && mac->enabled)
! 601: buffer_append(&output, (char *)macbuf, mac->mac_len);
! 602: #ifdef PACKET_DEBUG
! 603: fprintf(stderr, "encrypted: ");
! 604: buffer_dump(&output);
! 605: #endif
! 606: /* increment sequence number for outgoing packets */
! 607: if (++seqnr == 0)
! 608: log("outgoing seqnr wraps around");
! 609: buffer_clear(&outgoing_packet);
! 610:
! 611: if (type == SSH2_MSG_NEWKEYS) {
! 612: if (kex==NULL || mac==NULL || enc==NULL || comp==NULL)
! 613: fatal("packet_send2: no KEX");
! 614: if (mac->md != NULL)
! 615: mac->enabled = 1;
! 616: debug("cipher_set_key_iv send_context");
! 617: cipher_set_key_iv(&send_context, enc->type,
! 618: enc->key, enc->key_len,
! 619: enc->iv, enc->iv_len);
! 620: clear_enc_keys(enc, kex->we_need);
! 621: if (comp->type != 0 && comp->enabled == 0) {
! 622: comp->enabled = 1;
! 623: if (! packet_compression)
! 624: packet_start_compression(6);
! 625: }
! 626: }
! 627: }
! 628:
! 629: void
! 630: packet_send()
! 631: {
! 632: if (use_ssh2_packet_format)
! 633: packet_send2();
! 634: else
! 635: packet_send1();
! 636: DBG(debug("packet_send done"));
! 637: }
! 638:
! 639: void
! 640: packet_send_and_wait()
! 641: {
! 642: packet_send();
! 643: packet_write_wait();
! 644: }
! 645:
! 646: /*
1.16 markus 647: * Waits until a packet has been received, and returns its type. Note that
648: * no other data is processed until this returns, so this function should not
649: * be used during the interactive session.
650: */
1.1 deraadt 651:
1.2 provos 652: int
653: packet_read(int *payload_len_ptr)
1.1 deraadt 654: {
1.14 markus 655: int type, len;
656: fd_set set;
657: char buf[8192];
1.25 ! markus 658: DBG(debug("packet_read()"));
1.14 markus 659:
660: /* Since we are blocking, ensure that all written packets have been sent. */
661: packet_write_wait();
662:
663: /* Stay in the loop until we have received a complete packet. */
664: for (;;) {
665: /* Try to read a packet from the buffer. */
666: type = packet_read_poll(payload_len_ptr);
667: if (type == SSH_SMSG_SUCCESS
668: || type == SSH_SMSG_FAILURE
669: || type == SSH_CMSG_EOF
670: || type == SSH_CMSG_EXIT_CONFIRMATION)
671: packet_integrity_check(*payload_len_ptr, 0, type);
672: /* If we got a packet, return it. */
673: if (type != SSH_MSG_NONE)
674: return type;
1.16 markus 675: /*
676: * Otherwise, wait for some data to arrive, add it to the
677: * buffer, and try again.
678: */
1.14 markus 679: FD_ZERO(&set);
680: FD_SET(connection_in, &set);
1.16 markus 681:
1.14 markus 682: /* Wait for some data to arrive. */
683: select(connection_in + 1, &set, NULL, NULL, NULL);
1.16 markus 684:
1.14 markus 685: /* Read data from the socket. */
686: len = read(connection_in, buf, sizeof(buf));
1.18 markus 687: if (len == 0) {
688: log("Connection closed by %.200s", get_remote_ipaddr());
689: fatal_cleanup();
690: }
1.14 markus 691: if (len < 0)
692: fatal("Read from socket failed: %.100s", strerror(errno));
693: /* Append it to the buffer. */
694: packet_process_incoming(buf, len);
695: }
696: /* NOTREACHED */
1.1 deraadt 697: }
698:
1.16 markus 699: /*
700: * Waits until a packet has been received, verifies that its type matches
701: * that given, and gives a fatal error and exits if there is a mismatch.
702: */
1.1 deraadt 703:
1.2 provos 704: void
705: packet_read_expect(int *payload_len_ptr, int expected_type)
1.1 deraadt 706: {
1.14 markus 707: int type;
1.1 deraadt 708:
1.14 markus 709: type = packet_read(payload_len_ptr);
710: if (type != expected_type)
711: packet_disconnect("Protocol error: expected packet type %d, got %d",
1.25 ! markus 712: expected_type, type);
1.1 deraadt 713: }
714:
715: /* Checks if a full packet is available in the data received so far via
1.14 markus 716: * packet_process_incoming. If so, reads the packet; otherwise returns
717: * SSH_MSG_NONE. This does not wait for data from the connection.
718: *
719: * SSH_MSG_DISCONNECT is handled specially here. Also,
720: * SSH_MSG_IGNORE messages are skipped by this function and are never returned
721: * to higher levels.
722: *
723: * The returned payload_len does include space consumed by:
724: * Packet length
725: * Padding
726: * Packet type
727: * Check bytes
728: */
1.1 deraadt 729:
1.2 provos 730: int
1.25 ! markus 731: packet_read_poll1(int *payload_len_ptr)
1.1 deraadt 732: {
1.14 markus 733: unsigned int len, padded_len;
734: unsigned char *ucp;
1.25 ! markus 735: char buf[8], *cp;
1.14 markus 736: unsigned int checksum, stored_checksum;
737:
738: /* Check if input size is less than minimum packet size. */
739: if (buffer_len(&input) < 4 + 8)
740: return SSH_MSG_NONE;
741: /* Get length of incoming packet. */
742: ucp = (unsigned char *) buffer_ptr(&input);
743: len = GET_32BIT(ucp);
744: if (len < 1 + 2 + 2 || len > 256 * 1024)
745: packet_disconnect("Bad packet length %d.", len);
746: padded_len = (len + 8) & ~7;
747:
748: /* Check if the packet has been entirely received. */
749: if (buffer_len(&input) < 4 + padded_len)
750: return SSH_MSG_NONE;
751:
752: /* The entire packet is in buffer. */
753:
754: /* Consume packet length. */
755: buffer_consume(&input, 4);
756:
757: /* Copy data to incoming_packet. */
758: buffer_clear(&incoming_packet);
759: buffer_append_space(&incoming_packet, &cp, padded_len);
760: packet_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len);
761: buffer_consume(&input, padded_len);
1.1 deraadt 762:
763: #ifdef PACKET_DEBUG
1.14 markus 764: fprintf(stderr, "read_poll plain: ");
765: buffer_dump(&incoming_packet);
1.1 deraadt 766: #endif
767:
1.14 markus 768: /* Compute packet checksum. */
769: checksum = crc32((unsigned char *) buffer_ptr(&incoming_packet),
1.25 ! markus 770: buffer_len(&incoming_packet) - 4);
1.14 markus 771:
772: /* Skip padding. */
773: buffer_consume(&incoming_packet, 8 - len % 8);
774:
775: /* Test check bytes. */
776:
777: if (len != buffer_len(&incoming_packet))
778: packet_disconnect("packet_read_poll: len %d != buffer_len %d.",
1.25 ! markus 779: len, buffer_len(&incoming_packet));
1.14 markus 780:
781: ucp = (unsigned char *) buffer_ptr(&incoming_packet) + len - 4;
782: stored_checksum = GET_32BIT(ucp);
783: if (checksum != stored_checksum)
784: packet_disconnect("Corrupted check bytes on input.");
785: buffer_consume_end(&incoming_packet, 4);
786:
787: /* If using packet compression, decompress the packet. */
788: if (packet_compression) {
789: buffer_clear(&compression_buffer);
790: buffer_uncompress(&incoming_packet, &compression_buffer);
791: buffer_clear(&incoming_packet);
792: buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1.25 ! markus 793: buffer_len(&compression_buffer));
1.14 markus 794: }
795: /* Get packet type. */
796: buffer_get(&incoming_packet, &buf[0], 1);
797:
798: /* Return length of payload (without type field). */
799: *payload_len_ptr = buffer_len(&incoming_packet);
800:
801: /* Return type. */
802: return (unsigned char) buf[0];
1.1 deraadt 803: }
1.14 markus 804:
1.25 ! markus 805: int
! 806: packet_read_poll2(int *payload_len_ptr)
! 807: {
! 808: unsigned int padlen, need;
! 809: unsigned char buf[8], *macbuf;
! 810: unsigned char *ucp;
! 811: char *cp;
! 812: static unsigned int packet_length = 0;
! 813: static unsigned int seqnr = 0;
! 814: int type;
! 815: int maclen, block_size;
! 816: Enc *enc = NULL;
! 817: Mac *mac = NULL;
! 818: Comp *comp = NULL;
! 819:
! 820: if (kex != NULL) {
! 821: enc = &kex->enc[MODE_IN];
! 822: mac = &kex->mac[MODE_IN];
! 823: comp = &kex->comp[MODE_IN];
! 824: }
! 825: maclen = mac && mac->enabled ? mac->mac_len : 0;
! 826: block_size = enc ? enc->block_size : 8;
! 827:
! 828: if (packet_length == 0) {
! 829: /*
! 830: * check if input size is less than the cipher block size,
! 831: * decrypt first block and extract length of incoming packet
! 832: */
! 833: if (buffer_len(&input) < block_size)
! 834: return SSH_MSG_NONE;
! 835: buffer_clear(&incoming_packet);
! 836: buffer_append_space(&incoming_packet, &cp, block_size);
! 837: packet_decrypt(&receive_context, cp, buffer_ptr(&input),
! 838: block_size);
! 839: ucp = (unsigned char *) buffer_ptr(&incoming_packet);
! 840: packet_length = GET_32BIT(ucp);
! 841: if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
! 842: buffer_dump(&incoming_packet);
! 843: packet_disconnect("Bad packet length %d.", packet_length);
! 844: }
! 845: DBG(debug("input: packet len %d", packet_length+4));
! 846: buffer_consume(&input, block_size);
! 847: }
! 848: /* we have a partial packet of block_size bytes */
! 849: need = 4 + packet_length - block_size;
! 850: DBG(debug("partial packet %d, need %d, maclen %d", block_size,
! 851: need, maclen));
! 852: if (need % block_size != 0)
! 853: fatal("padding error: need %d block %d mod %d",
! 854: need, block_size, need % block_size);
! 855: /*
! 856: * check if the entire packet has been received and
! 857: * decrypt into incoming_packet
! 858: */
! 859: if (buffer_len(&input) < need + maclen)
! 860: return SSH_MSG_NONE;
! 861: #ifdef PACKET_DEBUG
! 862: fprintf(stderr, "read_poll enc/full: ");
! 863: buffer_dump(&input);
! 864: #endif
! 865: buffer_append_space(&incoming_packet, &cp, need);
! 866: packet_decrypt(&receive_context, cp, buffer_ptr(&input), need);
! 867: buffer_consume(&input, need);
! 868: /*
! 869: * compute MAC over seqnr and packet,
! 870: * increment sequence number for incoming packet
! 871: */
! 872: if (mac && mac->enabled) {
! 873: macbuf = hmac( mac->md, seqnr,
! 874: (unsigned char *) buffer_ptr(&incoming_packet),
! 875: buffer_len(&incoming_packet),
! 876: mac->key, mac->key_len
! 877: );
! 878: if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
! 879: packet_disconnect("Corrupted HMAC on input.");
! 880: DBG(debug("HMAC #%d ok", seqnr));
! 881: buffer_consume(&input, mac->mac_len);
! 882: }
! 883: if (++seqnr == 0)
! 884: log("incoming seqnr wraps around");
! 885:
! 886: /* get padlen */
! 887: cp = buffer_ptr(&incoming_packet) + 4;
! 888: padlen = *cp & 0xff;
! 889: DBG(debug("input: padlen %d", padlen));
! 890: if (padlen < 4)
! 891: packet_disconnect("Corrupted padlen %d on input.", padlen);
! 892:
! 893: /* skip packet size + padlen, discard padding */
! 894: buffer_consume(&incoming_packet, 4 + 1);
! 895: buffer_consume_end(&incoming_packet, padlen);
! 896:
! 897: DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
! 898: if (comp && comp->enabled) {
! 899: buffer_clear(&compression_buffer);
! 900: buffer_uncompress(&incoming_packet, &compression_buffer);
! 901: buffer_clear(&incoming_packet);
! 902: buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
! 903: buffer_len(&compression_buffer));
! 904: DBG(debug("input: len after de-compress %d", buffer_len(&incoming_packet)));
! 905: }
! 906: /*
! 907: * get packet type, implies consume.
! 908: * return length of payload (without type field)
! 909: */
! 910: buffer_get(&incoming_packet, (char *)&buf[0], 1);
! 911: *payload_len_ptr = buffer_len(&incoming_packet);
! 912:
! 913: /* reset for next packet */
! 914: packet_length = 0;
! 915:
! 916: /* extract packet type */
! 917: type = (unsigned char)buf[0];
! 918:
! 919: if (type == SSH2_MSG_NEWKEYS) {
! 920: if (kex==NULL || mac==NULL || enc==NULL || comp==NULL)
! 921: fatal("packet_read_poll2: no KEX");
! 922: if (mac->md != NULL)
! 923: mac->enabled = 1;
! 924: debug("cipher_set_key_iv receive_context");
! 925: cipher_set_key_iv(&receive_context, enc->type,
! 926: enc->key, enc->key_len,
! 927: enc->iv, enc->iv_len);
! 928: clear_enc_keys(enc, kex->we_need);
! 929: if (comp->type != 0 && comp->enabled == 0) {
! 930: comp->enabled = 1;
! 931: if (! packet_compression)
! 932: packet_start_compression(6);
! 933: }
! 934: }
! 935:
! 936: #ifdef PACKET_DEBUG
! 937: fprintf(stderr, "read/plain[%d]:\r\n",type);
! 938: buffer_dump(&incoming_packet);
! 939: #endif
! 940: return (unsigned char)type;
! 941: }
! 942:
! 943: int
! 944: packet_read_poll(int *payload_len_ptr)
! 945: {
! 946: char *msg;
! 947: for (;;) {
! 948: int type = use_ssh2_packet_format ?
! 949: packet_read_poll2(payload_len_ptr):
! 950: packet_read_poll1(payload_len_ptr);
! 951:
! 952: if(compat20) {
! 953: int reason;
! 954: if (type != 0)
! 955: DBG(debug("received packet type %d", type));
! 956: switch(type) {
! 957: case SSH2_MSG_IGNORE:
! 958: break;
! 959: case SSH2_MSG_DEBUG:
! 960: packet_get_char();
! 961: msg = packet_get_string(NULL);
! 962: debug("Remote: %.900s", msg);
! 963: xfree(msg);
! 964: msg = packet_get_string(NULL);
! 965: xfree(msg);
! 966: break;
! 967: case SSH2_MSG_DISCONNECT:
! 968: reason = packet_get_int();
! 969: msg = packet_get_string(NULL);
! 970: log("Received disconnect: %d: %.900s", reason, msg);
! 971: xfree(msg);
! 972: fatal_cleanup();
! 973: break;
! 974: default:
! 975: return type;
! 976: break;
! 977: }
! 978: } else {
! 979: switch(type) {
! 980: case SSH_MSG_IGNORE:
! 981: break;
! 982: case SSH_MSG_DEBUG:
! 983: msg = packet_get_string(NULL);
! 984: debug("Remote: %.900s", msg);
! 985: xfree(msg);
! 986: break;
! 987: case SSH_MSG_DISCONNECT:
! 988: msg = packet_get_string(NULL);
! 989: log("Received disconnect: %.900s", msg);
! 990: fatal_cleanup();
! 991: xfree(msg);
! 992: break;
! 993: default:
! 994: if (type != 0)
! 995: DBG(debug("received packet type %d", type));
! 996: return type;
! 997: break;
! 998: }
! 999: }
! 1000: }
! 1001: }
! 1002:
1.16 markus 1003: /*
1004: * Buffers the given amount of input characters. This is intended to be used
1005: * together with packet_read_poll.
1006: */
1.1 deraadt 1007:
1.2 provos 1008: void
1009: packet_process_incoming(const char *buf, unsigned int len)
1.1 deraadt 1010: {
1.14 markus 1011: buffer_append(&input, buf, len);
1.1 deraadt 1012: }
1013:
1014: /* Returns a character from the packet. */
1015:
1.2 provos 1016: unsigned int
1017: packet_get_char()
1.1 deraadt 1018: {
1.14 markus 1019: char ch;
1020: buffer_get(&incoming_packet, &ch, 1);
1021: return (unsigned char) ch;
1.1 deraadt 1022: }
1023:
1024: /* Returns an integer from the packet data. */
1025:
1.2 provos 1026: unsigned int
1027: packet_get_int()
1.1 deraadt 1028: {
1.14 markus 1029: return buffer_get_int(&incoming_packet);
1.1 deraadt 1030: }
1031:
1.16 markus 1032: /*
1033: * Returns an arbitrary precision integer from the packet data. The integer
1034: * must have been initialized before this call.
1035: */
1.1 deraadt 1036:
1.2 provos 1037: void
1.14 markus 1038: packet_get_bignum(BIGNUM * value, int *length_ptr)
1.1 deraadt 1039: {
1.14 markus 1040: *length_ptr = buffer_get_bignum(&incoming_packet, value);
1.24 markus 1041: }
1042:
1043: void
1044: packet_get_bignum2(BIGNUM * value, int *length_ptr)
1045: {
1046: *length_ptr = buffer_get_bignum2(&incoming_packet, value);
1047: }
1048:
1049: char *
1050: packet_get_raw(int *length_ptr)
1051: {
1052: int bytes = buffer_len(&incoming_packet);
1053: if (length_ptr != NULL)
1054: *length_ptr = bytes;
1055: return buffer_ptr(&incoming_packet);
1.1 deraadt 1056: }
1057:
1.16 markus 1058: /*
1059: * Returns a string from the packet data. The string is allocated using
1060: * xmalloc; it is the responsibility of the calling program to free it when
1061: * no longer needed. The length_ptr argument may be NULL, or point to an
1062: * integer into which the length of the string is stored.
1063: */
1.1 deraadt 1064:
1.16 markus 1065: char *
1.14 markus 1066: packet_get_string(unsigned int *length_ptr)
1.1 deraadt 1067: {
1.14 markus 1068: return buffer_get_string(&incoming_packet, length_ptr);
1.1 deraadt 1069: }
1070:
1.16 markus 1071: /*
1072: * Sends a diagnostic message from the server to the client. This message
1073: * can be sent at any time (but not while constructing another message). The
1074: * message is printed immediately, but only if the client is being executed
1075: * in verbose mode. These messages are primarily intended to ease debugging
1076: * authentication problems. The length of the formatted message must not
1077: * exceed 1024 bytes. This will automatically call packet_write_wait.
1078: */
1.1 deraadt 1079:
1.2 provos 1080: void
1.14 markus 1081: packet_send_debug(const char *fmt,...)
1.1 deraadt 1082: {
1.14 markus 1083: char buf[1024];
1084: va_list args;
1085:
1086: va_start(args, fmt);
1087: vsnprintf(buf, sizeof(buf), fmt, args);
1088: va_end(args);
1089:
1090: packet_start(SSH_MSG_DEBUG);
1091: packet_put_string(buf, strlen(buf));
1092: packet_send();
1093: packet_write_wait();
1.1 deraadt 1094: }
1095:
1.16 markus 1096: /*
1097: * Logs the error plus constructs and sends a disconnect packet, closes the
1098: * connection, and exits. This function never returns. The error message
1099: * should not contain a newline. The length of the formatted message must
1100: * not exceed 1024 bytes.
1101: */
1.1 deraadt 1102:
1.2 provos 1103: void
1.14 markus 1104: packet_disconnect(const char *fmt,...)
1.1 deraadt 1105: {
1.14 markus 1106: char buf[1024];
1107: va_list args;
1108: static int disconnecting = 0;
1109: if (disconnecting) /* Guard against recursive invocations. */
1110: fatal("packet_disconnect called recursively.");
1111: disconnecting = 1;
1112:
1.16 markus 1113: /*
1114: * Format the message. Note that the caller must make sure the
1115: * message is of limited size.
1116: */
1.14 markus 1117: va_start(args, fmt);
1118: vsnprintf(buf, sizeof(buf), fmt, args);
1119: va_end(args);
1120:
1121: /* Send the disconnect message to the other side, and wait for it to get sent. */
1.25 ! markus 1122: if (compat20) {
! 1123: packet_start(SSH2_MSG_DISCONNECT);
! 1124: packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
! 1125: packet_put_cstring(buf);
! 1126: packet_put_cstring("");
! 1127: } else {
! 1128: packet_start(SSH_MSG_DISCONNECT);
! 1129: packet_put_string(buf, strlen(buf));
! 1130: }
1.14 markus 1131: packet_send();
1132: packet_write_wait();
1133:
1134: /* Stop listening for connections. */
1135: channel_stop_listening();
1136:
1137: /* Close the connection. */
1138: packet_close();
1.1 deraadt 1139:
1.14 markus 1140: /* Display the error locally and exit. */
1.17 markus 1141: log("Disconnecting: %.100s", buf);
1142: fatal_cleanup();
1.1 deraadt 1143: }
1144:
1.16 markus 1145: /* Checks if there is any buffered output, and tries to write some of the output. */
1.1 deraadt 1146:
1.2 provos 1147: void
1148: packet_write_poll()
1.1 deraadt 1149: {
1.14 markus 1150: int len = buffer_len(&output);
1151: if (len > 0) {
1152: len = write(connection_out, buffer_ptr(&output), len);
1153: if (len <= 0) {
1154: if (errno == EAGAIN)
1155: return;
1156: else
1157: fatal("Write failed: %.100s", strerror(errno));
1158: }
1159: buffer_consume(&output, len);
1160: }
1.1 deraadt 1161: }
1162:
1.16 markus 1163: /*
1164: * Calls packet_write_poll repeatedly until all pending output data has been
1165: * written.
1166: */
1.1 deraadt 1167:
1.2 provos 1168: void
1169: packet_write_wait()
1.1 deraadt 1170: {
1.14 markus 1171: packet_write_poll();
1172: while (packet_have_data_to_write()) {
1173: fd_set set;
1174: FD_ZERO(&set);
1175: FD_SET(connection_out, &set);
1176: select(connection_out + 1, NULL, &set, NULL, NULL);
1177: packet_write_poll();
1178: }
1.1 deraadt 1179: }
1180:
1181: /* Returns true if there is buffered data to write to the connection. */
1182:
1.2 provos 1183: int
1184: packet_have_data_to_write()
1.1 deraadt 1185: {
1.14 markus 1186: return buffer_len(&output) != 0;
1.1 deraadt 1187: }
1188:
1189: /* Returns true if there is not too much data to write to the connection. */
1190:
1.2 provos 1191: int
1192: packet_not_very_much_data_to_write()
1.1 deraadt 1193: {
1.14 markus 1194: if (interactive_mode)
1195: return buffer_len(&output) < 16384;
1196: else
1197: return buffer_len(&output) < 128 * 1024;
1.1 deraadt 1198: }
1199:
1200: /* Informs that the current session is interactive. Sets IP flags for that. */
1201:
1.2 provos 1202: void
1203: packet_set_interactive(int interactive, int keepalives)
1.1 deraadt 1204: {
1.14 markus 1205: int on = 1;
1.1 deraadt 1206:
1.14 markus 1207: /* Record that we are in interactive mode. */
1208: interactive_mode = interactive;
1.1 deraadt 1209:
1.19 markus 1210: /* Only set socket options if using a socket. */
1211: if (!packet_connection_is_on_socket())
1.14 markus 1212: return;
1213: if (keepalives) {
1214: /* Set keepalives if requested. */
1215: if (setsockopt(connection_in, SOL_SOCKET, SO_KEEPALIVE, (void *) &on,
1.19 markus 1216: sizeof(on)) < 0)
1.14 markus 1217: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1218: }
1.19 markus 1219: /*
1220: * IPTOS_LOWDELAY, TCP_NODELAY and IPTOS_THROUGHPUT are IPv4 only
1221: */
1222: if (!packet_connection_is_ipv4())
1223: return;
1.14 markus 1224: if (interactive) {
1.16 markus 1225: /*
1226: * Set IP options for an interactive connection. Use
1227: * IPTOS_LOWDELAY and TCP_NODELAY.
1228: */
1.14 markus 1229: int lowdelay = IPTOS_LOWDELAY;
1230: if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &lowdelay,
1.19 markus 1231: sizeof(lowdelay)) < 0)
1.14 markus 1232: error("setsockopt IPTOS_LOWDELAY: %.100s", strerror(errno));
1233: if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on,
1.19 markus 1234: sizeof(on)) < 0)
1.14 markus 1235: error("setsockopt TCP_NODELAY: %.100s", strerror(errno));
1236: } else {
1.16 markus 1237: /*
1238: * Set IP options for a non-interactive connection. Use
1239: * IPTOS_THROUGHPUT.
1240: */
1.14 markus 1241: int throughput = IPTOS_THROUGHPUT;
1242: if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput,
1.19 markus 1243: sizeof(throughput)) < 0)
1.14 markus 1244: error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno));
1245: }
1.1 deraadt 1246: }
1247:
1248: /* Returns true if the current connection is interactive. */
1249:
1.2 provos 1250: int
1251: packet_is_interactive()
1.1 deraadt 1252: {
1.14 markus 1253: return interactive_mode;
1.12 markus 1254: }
1255:
1256: int
1257: packet_set_maxsize(int s)
1258: {
1.14 markus 1259: static int called = 0;
1260: if (called) {
1.25 ! markus 1261: log("packet_set_maxsize: called twice: old %d new %d",
! 1262: max_packet_size, s);
1.14 markus 1263: return -1;
1264: }
1265: if (s < 4 * 1024 || s > 1024 * 1024) {
1266: log("packet_set_maxsize: bad size %d", s);
1267: return -1;
1268: }
1269: log("packet_set_maxsize: setting to %d", s);
1270: max_packet_size = s;
1271: return s;
1.1 deraadt 1272: }