1 /*
2 * TLSv1 Record Protocol
3 * Copyright (c) 2006-2011, Jouni Malinen <j@w1.fi>
4 *
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
7 */
8
9 #include "includes.h"
10
11 #include "common.h"
12 #include "crypto/md5.h"
13 #include "crypto/sha1.h"
14 #include "crypto/sha256.h"
15 #include "tlsv1_common.h"
16 #include "tlsv1_record.h"
17
18
19 /**
20 * tlsv1_record_set_cipher_suite - TLS record layer: Set cipher suite
21 * @rl: Pointer to TLS record layer data
22 * @cipher_suite: New cipher suite
23 * Returns: 0 on success, -1 on failure
24 *
25 * This function is used to prepare TLS record layer for cipher suite change.
26 * tlsv1_record_change_write_cipher() and
27 * tlsv1_record_change_read_cipher() functions can then be used to change the
28 * currently used ciphers.
29 */
tlsv1_record_set_cipher_suite(struct tlsv1_record_layer * rl,u16 cipher_suite)30 int tlsv1_record_set_cipher_suite(struct tlsv1_record_layer *rl,
31 u16 cipher_suite)
32 {
33 const struct tls_cipher_suite *suite;
34 const struct tls_cipher_data *data;
35
36 wpa_printf(MSG_DEBUG, "TLSv1: Selected cipher suite: 0x%04x",
37 cipher_suite);
38 rl->cipher_suite = cipher_suite;
39
40 suite = tls_get_cipher_suite(cipher_suite);
41 if (suite == NULL)
42 return -1;
43
44 if (suite->hash == TLS_HASH_MD5) {
45 rl->hash_alg = CRYPTO_HASH_ALG_HMAC_MD5;
46 rl->hash_size = MD5_MAC_LEN;
47 } else if (suite->hash == TLS_HASH_SHA) {
48 rl->hash_alg = CRYPTO_HASH_ALG_HMAC_SHA1;
49 rl->hash_size = SHA1_MAC_LEN;
50 } else if (suite->hash == TLS_HASH_SHA256) {
51 rl->hash_alg = CRYPTO_HASH_ALG_HMAC_SHA256;
52 rl->hash_size = SHA256_MAC_LEN;
53 }
54
55 data = tls_get_cipher_data(suite->cipher);
56 if (data == NULL)
57 return -1;
58
59 rl->key_material_len = data->key_material;
60 rl->iv_size = data->block_size;
61 rl->cipher_alg = data->alg;
62
63 return 0;
64 }
65
66
67 /**
68 * tlsv1_record_change_write_cipher - TLS record layer: Change write cipher
69 * @rl: Pointer to TLS record layer data
70 * Returns: 0 on success (cipher changed), -1 on failure
71 *
72 * This function changes TLS record layer to use the new cipher suite
73 * configured with tlsv1_record_set_cipher_suite() for writing.
74 */
tlsv1_record_change_write_cipher(struct tlsv1_record_layer * rl)75 int tlsv1_record_change_write_cipher(struct tlsv1_record_layer *rl)
76 {
77 wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - New write cipher suite "
78 "0x%04x", rl->cipher_suite);
79 rl->write_cipher_suite = rl->cipher_suite;
80 os_memset(rl->write_seq_num, 0, TLS_SEQ_NUM_LEN);
81
82 if (rl->write_cbc) {
83 crypto_cipher_deinit(rl->write_cbc);
84 rl->write_cbc = NULL;
85 }
86 if (rl->cipher_alg != CRYPTO_CIPHER_NULL) {
87 rl->write_cbc = crypto_cipher_init(rl->cipher_alg,
88 rl->write_iv, rl->write_key,
89 rl->key_material_len);
90 if (rl->write_cbc == NULL) {
91 wpa_printf(MSG_DEBUG, "TLSv1: Failed to initialize "
92 "cipher");
93 return -1;
94 }
95 }
96
97 return 0;
98 }
99
100
101 /**
102 * tlsv1_record_change_read_cipher - TLS record layer: Change read cipher
103 * @rl: Pointer to TLS record layer data
104 * Returns: 0 on success (cipher changed), -1 on failure
105 *
106 * This function changes TLS record layer to use the new cipher suite
107 * configured with tlsv1_record_set_cipher_suite() for reading.
108 */
tlsv1_record_change_read_cipher(struct tlsv1_record_layer * rl)109 int tlsv1_record_change_read_cipher(struct tlsv1_record_layer *rl)
110 {
111 wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - New read cipher suite "
112 "0x%04x", rl->cipher_suite);
113 rl->read_cipher_suite = rl->cipher_suite;
114 os_memset(rl->read_seq_num, 0, TLS_SEQ_NUM_LEN);
115
116 if (rl->read_cbc) {
117 crypto_cipher_deinit(rl->read_cbc);
118 rl->read_cbc = NULL;
119 }
120 if (rl->cipher_alg != CRYPTO_CIPHER_NULL) {
121 rl->read_cbc = crypto_cipher_init(rl->cipher_alg,
122 rl->read_iv, rl->read_key,
123 rl->key_material_len);
124 if (rl->read_cbc == NULL) {
125 wpa_printf(MSG_DEBUG, "TLSv1: Failed to initialize "
126 "cipher");
127 return -1;
128 }
129 }
130
131 return 0;
132 }
133
134
135 /**
136 * tlsv1_record_send - TLS record layer: Send a message
137 * @rl: Pointer to TLS record layer data
138 * @content_type: Content type (TLS_CONTENT_TYPE_*)
139 * @buf: Buffer for the generated TLS message (needs to have extra space for
140 * header, IV (TLS v1.1), and HMAC)
141 * @buf_size: Maximum buf size
142 * @payload: Payload to be sent
143 * @payload_len: Length of the payload
144 * @out_len: Buffer for returning the used buf length
145 * Returns: 0 on success, -1 on failure
146 *
147 * This function fills in the TLS record layer header, adds HMAC, and encrypts
148 * the data using the current write cipher.
149 */
tlsv1_record_send(struct tlsv1_record_layer * rl,u8 content_type,u8 * buf,size_t buf_size,const u8 * payload,size_t payload_len,size_t * out_len)150 int tlsv1_record_send(struct tlsv1_record_layer *rl, u8 content_type, u8 *buf,
151 size_t buf_size, const u8 *payload, size_t payload_len,
152 size_t *out_len)
153 {
154 u8 *pos, *ct_start, *length, *cpayload;
155 struct crypto_hash *hmac;
156 size_t clen;
157 int explicit_iv;
158
159 pos = buf;
160 if (pos + TLS_RECORD_HEADER_LEN > buf + buf_size)
161 return -1;
162
163 /* ContentType type */
164 ct_start = pos;
165 *pos++ = content_type;
166 /* ProtocolVersion version */
167 WPA_PUT_BE16(pos, rl->tls_version);
168 pos += 2;
169 /* uint16 length */
170 length = pos;
171 WPA_PUT_BE16(length, payload_len);
172 pos += 2;
173
174 cpayload = pos;
175 explicit_iv = rl->write_cipher_suite != TLS_NULL_WITH_NULL_NULL &&
176 rl->iv_size && rl->tls_version >= TLS_VERSION_1_1;
177 if (explicit_iv) {
178 /* opaque IV[Cipherspec.block_length] */
179 if (pos + rl->iv_size > buf + buf_size)
180 return -1;
181
182 /*
183 * Use random number R per the RFC 4346, 6.2.3.2 CBC Block
184 * Cipher option 2a.
185 */
186
187 if (os_get_random(pos, rl->iv_size))
188 return -1;
189 pos += rl->iv_size;
190 }
191
192 /*
193 * opaque fragment[TLSPlaintext.length]
194 * (opaque content[TLSCompressed.length] in GenericBlockCipher)
195 */
196 if (pos + payload_len > buf + buf_size)
197 return -1;
198 os_memmove(pos, payload, payload_len);
199 pos += payload_len;
200
201 if (rl->write_cipher_suite != TLS_NULL_WITH_NULL_NULL) {
202 /*
203 * MAC calculated over seq_num + TLSCompressed.type +
204 * TLSCompressed.version + TLSCompressed.length +
205 * TLSCompressed.fragment
206 */
207 hmac = crypto_hash_init(rl->hash_alg, rl->write_mac_secret,
208 rl->hash_size);
209 if (hmac == NULL) {
210 wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - Failed "
211 "to initialize HMAC");
212 return -1;
213 }
214 crypto_hash_update(hmac, rl->write_seq_num, TLS_SEQ_NUM_LEN);
215 /* type + version + length + fragment */
216 crypto_hash_update(hmac, ct_start, TLS_RECORD_HEADER_LEN);
217 crypto_hash_update(hmac, payload, payload_len);
218 clen = buf + buf_size - pos;
219 if (clen < rl->hash_size) {
220 wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - Not "
221 "enough room for MAC");
222 crypto_hash_finish(hmac, NULL, NULL);
223 return -1;
224 }
225
226 if (crypto_hash_finish(hmac, pos, &clen) < 0) {
227 wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - Failed "
228 "to calculate HMAC");
229 return -1;
230 }
231 wpa_hexdump(MSG_MSGDUMP, "TLSv1: Record Layer - Write HMAC",
232 pos, clen);
233 pos += clen;
234 if (rl->iv_size) {
235 size_t len = pos - cpayload;
236 size_t pad;
237 pad = (len + 1) % rl->iv_size;
238 if (pad)
239 pad = rl->iv_size - pad;
240 if (pos + pad + 1 > buf + buf_size) {
241 wpa_printf(MSG_DEBUG, "TLSv1: No room for "
242 "block cipher padding");
243 return -1;
244 }
245 os_memset(pos, pad, pad + 1);
246 pos += pad + 1;
247 }
248
249 if (crypto_cipher_encrypt(rl->write_cbc, cpayload,
250 cpayload, pos - cpayload) < 0)
251 return -1;
252 }
253
254 WPA_PUT_BE16(length, pos - length - 2);
255 inc_byte_array(rl->write_seq_num, TLS_SEQ_NUM_LEN);
256
257 *out_len = pos - buf;
258
259 return 0;
260 }
261
262
263 /**
264 * tlsv1_record_receive - TLS record layer: Process a received message
265 * @rl: Pointer to TLS record layer data
266 * @in_data: Received data
267 * @in_len: Length of the received data
268 * @out_data: Buffer for output data (must be at least as long as in_data)
269 * @out_len: Set to maximum out_data length by caller; used to return the
270 * length of the used data
271 * @alert: Buffer for returning an alert value on failure
272 * Returns: Number of bytes used from in_data on success, 0 if record was not
273 * complete (more data needed), or -1 on failure
274 *
275 * This function decrypts the received message, verifies HMAC and TLS record
276 * layer header.
277 */
tlsv1_record_receive(struct tlsv1_record_layer * rl,const u8 * in_data,size_t in_len,u8 * out_data,size_t * out_len,u8 * alert)278 int tlsv1_record_receive(struct tlsv1_record_layer *rl,
279 const u8 *in_data, size_t in_len,
280 u8 *out_data, size_t *out_len, u8 *alert)
281 {
282 size_t i, rlen, hlen;
283 u8 padlen;
284 struct crypto_hash *hmac;
285 u8 len[2], hash[100];
286 int force_mac_error = 0;
287 u8 ct;
288
289 if (in_len < TLS_RECORD_HEADER_LEN) {
290 wpa_printf(MSG_DEBUG, "TLSv1: Too short record (in_len=%lu) - "
291 "need more data",
292 (unsigned long) in_len);
293 wpa_hexdump(MSG_MSGDUMP, "TLSv1: Record Layer - Received",
294 in_data, in_len);
295 return 0;
296 }
297
298 ct = in_data[0];
299 rlen = WPA_GET_BE16(in_data + 3);
300 wpa_printf(MSG_DEBUG, "TLSv1: Received content type %d version %d.%d "
301 "length %d", ct, in_data[1], in_data[2], (int) rlen);
302
303 /*
304 * TLS v1.0 and v1.1 RFCs were not exactly clear on the use of the
305 * protocol version in record layer. As such, accept any {03,xx} value
306 * to remain compatible with existing implementations.
307 */
308 if (in_data[1] != 0x03) {
309 wpa_printf(MSG_DEBUG, "TLSv1: Unexpected protocol version "
310 "%u.%u", in_data[1], in_data[2]);
311 *alert = TLS_ALERT_PROTOCOL_VERSION;
312 return -1;
313 }
314
315 /* TLSCiphertext must not be more than 2^14+2048 bytes */
316 if (TLS_RECORD_HEADER_LEN + rlen > 18432) {
317 wpa_printf(MSG_DEBUG, "TLSv1: Record overflow (len=%lu)",
318 (unsigned long) (TLS_RECORD_HEADER_LEN + rlen));
319 *alert = TLS_ALERT_RECORD_OVERFLOW;
320 return -1;
321 }
322
323 in_data += TLS_RECORD_HEADER_LEN;
324 in_len -= TLS_RECORD_HEADER_LEN;
325
326 if (rlen > in_len) {
327 wpa_printf(MSG_DEBUG, "TLSv1: Not all record data included "
328 "(rlen=%lu > in_len=%lu)",
329 (unsigned long) rlen, (unsigned long) in_len);
330 return 0;
331 }
332
333 wpa_hexdump(MSG_MSGDUMP, "TLSv1: Record Layer - Received",
334 in_data, rlen);
335
336 if (ct != TLS_CONTENT_TYPE_HANDSHAKE &&
337 ct != TLS_CONTENT_TYPE_CHANGE_CIPHER_SPEC &&
338 ct != TLS_CONTENT_TYPE_ALERT &&
339 ct != TLS_CONTENT_TYPE_APPLICATION_DATA) {
340 wpa_printf(MSG_DEBUG, "TLSv1: Ignore record with unknown "
341 "content type 0x%x", ct);
342 *alert = TLS_ALERT_UNEXPECTED_MESSAGE;
343 return -1;
344 }
345
346 in_len = rlen;
347
348 if (*out_len < in_len) {
349 wpa_printf(MSG_DEBUG, "TLSv1: Not enough output buffer for "
350 "processing received record");
351 *alert = TLS_ALERT_INTERNAL_ERROR;
352 return -1;
353 }
354
355 if (rl->read_cipher_suite != TLS_NULL_WITH_NULL_NULL) {
356 size_t plen;
357 if (crypto_cipher_decrypt(rl->read_cbc, in_data,
358 out_data, in_len) < 0) {
359 *alert = TLS_ALERT_DECRYPTION_FAILED;
360 return -1;
361 }
362 plen = in_len;
363 wpa_hexdump_key(MSG_MSGDUMP, "TLSv1: Record Layer - Decrypted "
364 "data", out_data, plen);
365
366 if (rl->iv_size) {
367 /*
368 * TLS v1.0 defines different alert values for various
369 * failures. That may information to aid in attacks, so
370 * use the same bad_record_mac alert regardless of the
371 * issues.
372 *
373 * In addition, instead of returning immediately on
374 * error, run through the MAC check to make timing
375 * attacks more difficult.
376 */
377
378 if (rl->tls_version >= TLS_VERSION_1_1) {
379 /* Remove opaque IV[Cipherspec.block_length] */
380 if (plen < rl->iv_size) {
381 wpa_printf(MSG_DEBUG, "TLSv1.1: Not "
382 "enough room for IV");
383 force_mac_error = 1;
384 goto check_mac;
385 }
386 os_memmove(out_data, out_data + rl->iv_size,
387 plen - rl->iv_size);
388 plen -= rl->iv_size;
389 }
390
391 /* Verify and remove padding */
392 if (plen == 0) {
393 wpa_printf(MSG_DEBUG, "TLSv1: Too short record"
394 " (no pad)");
395 force_mac_error = 1;
396 goto check_mac;
397 }
398 padlen = out_data[plen - 1];
399 if (padlen >= plen) {
400 wpa_printf(MSG_DEBUG, "TLSv1: Incorrect pad "
401 "length (%u, plen=%lu) in "
402 "received record",
403 padlen, (unsigned long) plen);
404 force_mac_error = 1;
405 goto check_mac;
406 }
407 for (i = plen - padlen - 1; i < plen - 1; i++) {
408 if (out_data[i] != padlen) {
409 wpa_hexdump(MSG_DEBUG,
410 "TLSv1: Invalid pad in "
411 "received record",
412 out_data + plen - padlen -
413 1, padlen + 1);
414 force_mac_error = 1;
415 goto check_mac;
416 }
417 }
418
419 plen -= padlen + 1;
420
421 wpa_hexdump_key(MSG_MSGDUMP, "TLSv1: Record Layer - "
422 "Decrypted data with IV and padding "
423 "removed", out_data, plen);
424 }
425
426 check_mac:
427 if (plen < rl->hash_size) {
428 wpa_printf(MSG_DEBUG, "TLSv1: Too short record; no "
429 "hash value");
430 *alert = TLS_ALERT_BAD_RECORD_MAC;
431 return -1;
432 }
433
434 plen -= rl->hash_size;
435
436 hmac = crypto_hash_init(rl->hash_alg, rl->read_mac_secret,
437 rl->hash_size);
438 if (hmac == NULL) {
439 wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - Failed "
440 "to initialize HMAC");
441 *alert = TLS_ALERT_INTERNAL_ERROR;
442 return -1;
443 }
444
445 crypto_hash_update(hmac, rl->read_seq_num, TLS_SEQ_NUM_LEN);
446 /* type + version + length + fragment */
447 crypto_hash_update(hmac, in_data - TLS_RECORD_HEADER_LEN, 3);
448 WPA_PUT_BE16(len, plen);
449 crypto_hash_update(hmac, len, 2);
450 crypto_hash_update(hmac, out_data, plen);
451 hlen = sizeof(hash);
452 if (crypto_hash_finish(hmac, hash, &hlen) < 0) {
453 wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - Failed "
454 "to calculate HMAC");
455 *alert = TLS_ALERT_INTERNAL_ERROR;
456 return -1;
457 }
458 if (hlen != rl->hash_size ||
459 os_memcmp_const(hash, out_data + plen, hlen) != 0 ||
460 force_mac_error) {
461 wpa_printf(MSG_DEBUG, "TLSv1: Invalid HMAC value in "
462 "received message (force_mac_error=%d)",
463 force_mac_error);
464 *alert = TLS_ALERT_BAD_RECORD_MAC;
465 return -1;
466 }
467
468 *out_len = plen;
469 } else {
470 os_memcpy(out_data, in_data, in_len);
471 *out_len = in_len;
472 }
473
474 /* TLSCompressed must not be more than 2^14+1024 bytes */
475 if (TLS_RECORD_HEADER_LEN + *out_len > 17408) {
476 wpa_printf(MSG_DEBUG, "TLSv1: Record overflow (len=%lu)",
477 (unsigned long) (TLS_RECORD_HEADER_LEN + *out_len));
478 *alert = TLS_ALERT_RECORD_OVERFLOW;
479 return -1;
480 }
481
482 inc_byte_array(rl->read_seq_num, TLS_SEQ_NUM_LEN);
483
484 return TLS_RECORD_HEADER_LEN + rlen;
485 }
486
