1 /*
2 * Generic SSL/TLS messaging layer functions
3 * (record layer + retransmission state machine)
4 *
5 * Copyright The Mbed TLS Contributors
6 * SPDX-License-Identifier: Apache-2.0
7 *
8 * Licensed under the Apache License, Version 2.0 (the "License"); you may
9 * not use this file except in compliance with the License.
10 * You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
16 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 */
20 /*
21 * http://www.ietf.org/rfc/rfc2246.txt
22 * http://www.ietf.org/rfc/rfc4346.txt
23 */
24
25 #include "common.h"
26
27 #if defined(MBEDTLS_SSL_TLS_C)
28
29 #include "mbedtls/platform.h"
30
31 #include "mbedtls/ssl.h"
32 #include "ssl_misc.h"
33 #include "mbedtls/debug.h"
34 #include "mbedtls/error.h"
35 #include "mbedtls/platform_util.h"
36 #include "mbedtls/version.h"
37 #include "constant_time_internal.h"
38 #include "mbedtls/constant_time.h"
39
40 #include <string.h>
41
42 #if defined(MBEDTLS_USE_PSA_CRYPTO)
43 #include "mbedtls/psa_util.h"
44 #include "psa/crypto.h"
45 #endif
46
47 #if defined(MBEDTLS_X509_CRT_PARSE_C)
48 #include "mbedtls/oid.h"
49 #endif
50
51 #if defined(MBEDTLS_USE_PSA_CRYPTO)
52 #define PSA_TO_MBEDTLS_ERR(status) PSA_TO_MBEDTLS_ERR_LIST(status, \
53 psa_to_ssl_errors, \
54 psa_generic_status_to_mbedtls)
55 #endif
56
57 static uint32_t ssl_get_hs_total_len(mbedtls_ssl_context const *ssl);
58
59 /*
60 * Start a timer.
61 * Passing millisecs = 0 cancels a running timer.
62 */
mbedtls_ssl_set_timer(mbedtls_ssl_context * ssl,uint32_t millisecs)63 void mbedtls_ssl_set_timer(mbedtls_ssl_context *ssl, uint32_t millisecs)
64 {
65 if (ssl->f_set_timer == NULL) {
66 return;
67 }
68
69 MBEDTLS_SSL_DEBUG_MSG(3, ("set_timer to %d ms", (int) millisecs));
70 ssl->f_set_timer(ssl->p_timer, millisecs / 4, millisecs);
71 }
72
73 /*
74 * Return -1 is timer is expired, 0 if it isn't.
75 */
mbedtls_ssl_check_timer(mbedtls_ssl_context * ssl)76 int mbedtls_ssl_check_timer(mbedtls_ssl_context *ssl)
77 {
78 if (ssl->f_get_timer == NULL) {
79 return 0;
80 }
81
82 if (ssl->f_get_timer(ssl->p_timer) == 2) {
83 MBEDTLS_SSL_DEBUG_MSG(3, ("timer expired"));
84 return -1;
85 }
86
87 return 0;
88 }
89
90 MBEDTLS_CHECK_RETURN_CRITICAL
91 static int ssl_parse_record_header(mbedtls_ssl_context const *ssl,
92 unsigned char *buf,
93 size_t len,
94 mbedtls_record *rec);
95
mbedtls_ssl_check_record(mbedtls_ssl_context const * ssl,unsigned char * buf,size_t buflen)96 int mbedtls_ssl_check_record(mbedtls_ssl_context const *ssl,
97 unsigned char *buf,
98 size_t buflen)
99 {
100 int ret = 0;
101 MBEDTLS_SSL_DEBUG_MSG(1, ("=> mbedtls_ssl_check_record"));
102 MBEDTLS_SSL_DEBUG_BUF(3, "record buffer", buf, buflen);
103
104 /* We don't support record checking in TLS because
105 * there doesn't seem to be a usecase for it.
106 */
107 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_STREAM) {
108 ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
109 goto exit;
110 }
111 #if defined(MBEDTLS_SSL_PROTO_DTLS)
112 else {
113 mbedtls_record rec;
114
115 ret = ssl_parse_record_header(ssl, buf, buflen, &rec);
116 if (ret != 0) {
117 MBEDTLS_SSL_DEBUG_RET(3, "ssl_parse_record_header", ret);
118 goto exit;
119 }
120
121 if (ssl->transform_in != NULL) {
122 ret = mbedtls_ssl_decrypt_buf(ssl, ssl->transform_in, &rec);
123 if (ret != 0) {
124 MBEDTLS_SSL_DEBUG_RET(3, "mbedtls_ssl_decrypt_buf", ret);
125 goto exit;
126 }
127 }
128 }
129 #endif /* MBEDTLS_SSL_PROTO_DTLS */
130
131 exit:
132 /* On success, we have decrypted the buffer in-place, so make
133 * sure we don't leak any plaintext data. */
134 mbedtls_platform_zeroize(buf, buflen);
135
136 /* For the purpose of this API, treat messages with unexpected CID
137 * as well as such from future epochs as unexpected. */
138 if (ret == MBEDTLS_ERR_SSL_UNEXPECTED_CID ||
139 ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE) {
140 ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD;
141 }
142
143 MBEDTLS_SSL_DEBUG_MSG(1, ("<= mbedtls_ssl_check_record"));
144 return ret;
145 }
146
147 #define SSL_DONT_FORCE_FLUSH 0
148 #define SSL_FORCE_FLUSH 1
149
150 #if defined(MBEDTLS_SSL_PROTO_DTLS)
151
152 /* Forward declarations for functions related to message buffering. */
153 static void ssl_buffering_free_slot(mbedtls_ssl_context *ssl,
154 uint8_t slot);
155 static void ssl_free_buffered_record(mbedtls_ssl_context *ssl);
156 MBEDTLS_CHECK_RETURN_CRITICAL
157 static int ssl_load_buffered_message(mbedtls_ssl_context *ssl);
158 MBEDTLS_CHECK_RETURN_CRITICAL
159 static int ssl_load_buffered_record(mbedtls_ssl_context *ssl);
160 MBEDTLS_CHECK_RETURN_CRITICAL
161 static int ssl_buffer_message(mbedtls_ssl_context *ssl);
162 MBEDTLS_CHECK_RETURN_CRITICAL
163 static int ssl_buffer_future_record(mbedtls_ssl_context *ssl,
164 mbedtls_record const *rec);
165 MBEDTLS_CHECK_RETURN_CRITICAL
166 static int ssl_next_record_is_in_datagram(mbedtls_ssl_context *ssl);
167
ssl_get_maximum_datagram_size(mbedtls_ssl_context const * ssl)168 static size_t ssl_get_maximum_datagram_size(mbedtls_ssl_context const *ssl)
169 {
170 size_t mtu = mbedtls_ssl_get_current_mtu(ssl);
171 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
172 size_t out_buf_len = ssl->out_buf_len;
173 #else
174 size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN;
175 #endif
176
177 if (mtu != 0 && mtu < out_buf_len) {
178 return mtu;
179 }
180
181 return out_buf_len;
182 }
183
184 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_get_remaining_space_in_datagram(mbedtls_ssl_context const * ssl)185 static int ssl_get_remaining_space_in_datagram(mbedtls_ssl_context const *ssl)
186 {
187 size_t const bytes_written = ssl->out_left;
188 size_t const mtu = ssl_get_maximum_datagram_size(ssl);
189
190 /* Double-check that the write-index hasn't gone
191 * past what we can transmit in a single datagram. */
192 if (bytes_written > mtu) {
193 /* Should never happen... */
194 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
195 }
196
197 return (int) (mtu - bytes_written);
198 }
199
200 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_get_remaining_payload_in_datagram(mbedtls_ssl_context const * ssl)201 static int ssl_get_remaining_payload_in_datagram(mbedtls_ssl_context const *ssl)
202 {
203 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
204 size_t remaining, expansion;
205 size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN;
206
207 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
208 const size_t mfl = mbedtls_ssl_get_output_max_frag_len(ssl);
209
210 if (max_len > mfl) {
211 max_len = mfl;
212 }
213
214 /* By the standard (RFC 6066 Sect. 4), the MFL extension
215 * only limits the maximum record payload size, so in theory
216 * we would be allowed to pack multiple records of payload size
217 * MFL into a single datagram. However, this would mean that there's
218 * no way to explicitly communicate MTU restrictions to the peer.
219 *
220 * The following reduction of max_len makes sure that we never
221 * write datagrams larger than MFL + Record Expansion Overhead.
222 */
223 if (max_len <= ssl->out_left) {
224 return 0;
225 }
226
227 max_len -= ssl->out_left;
228 #endif
229
230 ret = ssl_get_remaining_space_in_datagram(ssl);
231 if (ret < 0) {
232 return ret;
233 }
234 remaining = (size_t) ret;
235
236 ret = mbedtls_ssl_get_record_expansion(ssl);
237 if (ret < 0) {
238 return ret;
239 }
240 expansion = (size_t) ret;
241
242 if (remaining <= expansion) {
243 return 0;
244 }
245
246 remaining -= expansion;
247 if (remaining >= max_len) {
248 remaining = max_len;
249 }
250
251 return (int) remaining;
252 }
253
254 /*
255 * Double the retransmit timeout value, within the allowed range,
256 * returning -1 if the maximum value has already been reached.
257 */
258 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_double_retransmit_timeout(mbedtls_ssl_context * ssl)259 static int ssl_double_retransmit_timeout(mbedtls_ssl_context *ssl)
260 {
261 uint32_t new_timeout;
262
263 if (ssl->handshake->retransmit_timeout >= ssl->conf->hs_timeout_max) {
264 return -1;
265 }
266
267 /* Implement the final paragraph of RFC 6347 section 4.1.1.1
268 * in the following way: after the initial transmission and a first
269 * retransmission, back off to a temporary estimated MTU of 508 bytes.
270 * This value is guaranteed to be deliverable (if not guaranteed to be
271 * delivered) of any compliant IPv4 (and IPv6) network, and should work
272 * on most non-IP stacks too. */
273 if (ssl->handshake->retransmit_timeout != ssl->conf->hs_timeout_min) {
274 ssl->handshake->mtu = 508;
275 MBEDTLS_SSL_DEBUG_MSG(2, ("mtu autoreduction to %d bytes", ssl->handshake->mtu));
276 }
277
278 new_timeout = 2 * ssl->handshake->retransmit_timeout;
279
280 /* Avoid arithmetic overflow and range overflow */
281 if (new_timeout < ssl->handshake->retransmit_timeout ||
282 new_timeout > ssl->conf->hs_timeout_max) {
283 new_timeout = ssl->conf->hs_timeout_max;
284 }
285
286 ssl->handshake->retransmit_timeout = new_timeout;
287 MBEDTLS_SSL_DEBUG_MSG(3, ("update timeout value to %lu millisecs",
288 (unsigned long) ssl->handshake->retransmit_timeout));
289
290 return 0;
291 }
292
ssl_reset_retransmit_timeout(mbedtls_ssl_context * ssl)293 static void ssl_reset_retransmit_timeout(mbedtls_ssl_context *ssl)
294 {
295 ssl->handshake->retransmit_timeout = ssl->conf->hs_timeout_min;
296 MBEDTLS_SSL_DEBUG_MSG(3, ("update timeout value to %lu millisecs",
297 (unsigned long) ssl->handshake->retransmit_timeout));
298 }
299 #endif /* MBEDTLS_SSL_PROTO_DTLS */
300
301 /*
302 * Encryption/decryption functions
303 */
304
305 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) || defined(MBEDTLS_SSL_PROTO_TLS1_3)
306
ssl_compute_padding_length(size_t len,size_t granularity)307 static size_t ssl_compute_padding_length(size_t len,
308 size_t granularity)
309 {
310 return (granularity - (len + 1) % granularity) % granularity;
311 }
312
313 /* This functions transforms a (D)TLS plaintext fragment and a record content
314 * type into an instance of the (D)TLSInnerPlaintext structure. This is used
315 * in DTLS 1.2 + CID and within TLS 1.3 to allow flexible padding and to protect
316 * a record's content type.
317 *
318 * struct {
319 * opaque content[DTLSPlaintext.length];
320 * ContentType real_type;
321 * uint8 zeros[length_of_padding];
322 * } (D)TLSInnerPlaintext;
323 *
324 * Input:
325 * - `content`: The beginning of the buffer holding the
326 * plaintext to be wrapped.
327 * - `*content_size`: The length of the plaintext in Bytes.
328 * - `max_len`: The number of Bytes available starting from
329 * `content`. This must be `>= *content_size`.
330 * - `rec_type`: The desired record content type.
331 *
332 * Output:
333 * - `content`: The beginning of the resulting (D)TLSInnerPlaintext structure.
334 * - `*content_size`: The length of the resulting (D)TLSInnerPlaintext structure.
335 *
336 * Returns:
337 * - `0` on success.
338 * - A negative error code if `max_len` didn't offer enough space
339 * for the expansion.
340 */
341 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_build_inner_plaintext(unsigned char * content,size_t * content_size,size_t remaining,uint8_t rec_type,size_t pad)342 static int ssl_build_inner_plaintext(unsigned char *content,
343 size_t *content_size,
344 size_t remaining,
345 uint8_t rec_type,
346 size_t pad)
347 {
348 size_t len = *content_size;
349
350 /* Write real content type */
351 if (remaining == 0) {
352 return -1;
353 }
354 content[len] = rec_type;
355 len++;
356 remaining--;
357
358 if (remaining < pad) {
359 return -1;
360 }
361 memset(content + len, 0, pad);
362 len += pad;
363 remaining -= pad;
364
365 *content_size = len;
366 return 0;
367 }
368
369 /* This function parses a (D)TLSInnerPlaintext structure.
370 * See ssl_build_inner_plaintext() for details. */
371 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_parse_inner_plaintext(unsigned char const * content,size_t * content_size,uint8_t * rec_type)372 static int ssl_parse_inner_plaintext(unsigned char const *content,
373 size_t *content_size,
374 uint8_t *rec_type)
375 {
376 size_t remaining = *content_size;
377
378 /* Determine length of padding by skipping zeroes from the back. */
379 do {
380 if (remaining == 0) {
381 return -1;
382 }
383 remaining--;
384 } while (content[remaining] == 0);
385
386 *content_size = remaining;
387 *rec_type = content[remaining];
388
389 return 0;
390 }
391 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID || MBEDTLS_SSL_PROTO_TLS1_3 */
392
393 /* The size of the `add_data` structure depends on various
394 * factors, namely
395 *
396 * 1) CID functionality disabled
397 *
398 * additional_data =
399 * 8: seq_num +
400 * 1: type +
401 * 2: version +
402 * 2: length of inner plaintext +
403 *
404 * size = 13 bytes
405 *
406 * 2) CID functionality based on RFC 9146 enabled
407 *
408 * size = 8 + 1 + 1 + 1 + 2 + 2 + 6 + 2 + CID-length
409 * = 23 + CID-length
410 *
411 * 3) CID functionality based on legacy CID version
412 according to draft-ietf-tls-dtls-connection-id-05
413 * https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05
414 *
415 * size = 13 + 1 + CID-length
416 *
417 * More information about the CID usage:
418 *
419 * Per Section 5.3 of draft-ietf-tls-dtls-connection-id-05 the
420 * size of the additional data structure is calculated as:
421 *
422 * additional_data =
423 * 8: seq_num +
424 * 1: tls12_cid +
425 * 2: DTLSCipherText.version +
426 * n: cid +
427 * 1: cid_length +
428 * 2: length_of_DTLSInnerPlaintext
429 *
430 * Per RFC 9146 the size of the add_data structure is calculated as:
431 *
432 * additional_data =
433 * 8: seq_num_placeholder +
434 * 1: tls12_cid +
435 * 1: cid_length +
436 * 1: tls12_cid +
437 * 2: DTLSCiphertext.version +
438 * 2: epoch +
439 * 6: sequence_number +
440 * n: cid +
441 * 2: length_of_DTLSInnerPlaintext
442 *
443 */
ssl_extract_add_data_from_record(unsigned char * add_data,size_t * add_data_len,mbedtls_record * rec,mbedtls_ssl_protocol_version tls_version,size_t taglen)444 static void ssl_extract_add_data_from_record(unsigned char *add_data,
445 size_t *add_data_len,
446 mbedtls_record *rec,
447 mbedtls_ssl_protocol_version
448 tls_version,
449 size_t taglen)
450 {
451 /* Several types of ciphers have been defined for use with TLS and DTLS,
452 * and the MAC calculations for those ciphers differ slightly. Further
453 * variants were added when the CID functionality was added with RFC 9146.
454 * This implementations also considers the use of a legacy version of the
455 * CID specification published in draft-ietf-tls-dtls-connection-id-05,
456 * which is used in deployments.
457 *
458 * We will distinguish between the non-CID and the CID cases below.
459 *
460 * --- Non-CID cases ---
461 *
462 * Quoting RFC 5246 (TLS 1.2):
463 *
464 * additional_data = seq_num + TLSCompressed.type +
465 * TLSCompressed.version + TLSCompressed.length;
466 *
467 * For TLS 1.3, the record sequence number is dropped from the AAD
468 * and encoded within the nonce of the AEAD operation instead.
469 * Moreover, the additional data involves the length of the TLS
470 * ciphertext, not the TLS plaintext as in earlier versions.
471 * Quoting RFC 8446 (TLS 1.3):
472 *
473 * additional_data = TLSCiphertext.opaque_type ||
474 * TLSCiphertext.legacy_record_version ||
475 * TLSCiphertext.length
476 *
477 * We pass the tag length to this function in order to compute the
478 * ciphertext length from the inner plaintext length rec->data_len via
479 *
480 * TLSCiphertext.length = TLSInnerPlaintext.length + taglen.
481 *
482 * --- CID cases ---
483 *
484 * RFC 9146 uses a common pattern when constructing the data
485 * passed into a MAC / AEAD cipher.
486 *
487 * Data concatenation for MACs used with block ciphers with
488 * Encrypt-then-MAC Processing (with CID):
489 *
490 * data = seq_num_placeholder +
491 * tls12_cid +
492 * cid_length +
493 * tls12_cid +
494 * DTLSCiphertext.version +
495 * epoch +
496 * sequence_number +
497 * cid +
498 * DTLSCiphertext.length +
499 * IV +
500 * ENC(content + padding + padding_length)
501 *
502 * Data concatenation for MACs used with block ciphers (with CID):
503 *
504 * data = seq_num_placeholder +
505 * tls12_cid +
506 * cid_length +
507 * tls12_cid +
508 * DTLSCiphertext.version +
509 * epoch +
510 * sequence_number +
511 * cid +
512 * length_of_DTLSInnerPlaintext +
513 * DTLSInnerPlaintext.content +
514 * DTLSInnerPlaintext.real_type +
515 * DTLSInnerPlaintext.zeros
516 *
517 * AEAD ciphers use the following additional data calculation (with CIDs):
518 *
519 * additional_data = seq_num_placeholder +
520 * tls12_cid +
521 * cid_length +
522 * tls12_cid +
523 * DTLSCiphertext.version +
524 * epoch +
525 * sequence_number +
526 * cid +
527 * length_of_DTLSInnerPlaintext
528 *
529 * Section 5.3 of draft-ietf-tls-dtls-connection-id-05 (for legacy CID use)
530 * defines the additional data calculation as follows:
531 *
532 * additional_data = seq_num +
533 * tls12_cid +
534 * DTLSCipherText.version +
535 * cid +
536 * cid_length +
537 * length_of_DTLSInnerPlaintext
538 */
539
540 unsigned char *cur = add_data;
541 size_t ad_len_field = rec->data_len;
542
543 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \
544 MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0
545 const unsigned char seq_num_placeholder[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
546 #endif
547
548 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
549 if (tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
550 /* In TLS 1.3, the AAD contains the length of the TLSCiphertext,
551 * which differs from the length of the TLSInnerPlaintext
552 * by the length of the authentication tag. */
553 ad_len_field += taglen;
554 } else
555 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
556 {
557 ((void) tls_version);
558 ((void) taglen);
559
560 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \
561 MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0
562 if (rec->cid_len != 0) {
563 // seq_num_placeholder
564 memcpy(cur, seq_num_placeholder, sizeof(seq_num_placeholder));
565 cur += sizeof(seq_num_placeholder);
566
567 // tls12_cid type
568 *cur = rec->type;
569 cur++;
570
571 // cid_length
572 *cur = rec->cid_len;
573 cur++;
574 } else
575 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
576 {
577 // epoch + sequence number
578 memcpy(cur, rec->ctr, sizeof(rec->ctr));
579 cur += sizeof(rec->ctr);
580 }
581 }
582
583 // type
584 *cur = rec->type;
585 cur++;
586
587 // version
588 memcpy(cur, rec->ver, sizeof(rec->ver));
589 cur += sizeof(rec->ver);
590
591 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \
592 MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 1
593
594 if (rec->cid_len != 0) {
595 // CID
596 memcpy(cur, rec->cid, rec->cid_len);
597 cur += rec->cid_len;
598
599 // cid_length
600 *cur = rec->cid_len;
601 cur++;
602
603 // length of inner plaintext
604 MBEDTLS_PUT_UINT16_BE(ad_len_field, cur, 0);
605 cur += 2;
606 } else
607 #elif defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \
608 MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0
609
610 if (rec->cid_len != 0) {
611 // epoch + sequence number
612 memcpy(cur, rec->ctr, sizeof(rec->ctr));
613 cur += sizeof(rec->ctr);
614
615 // CID
616 memcpy(cur, rec->cid, rec->cid_len);
617 cur += rec->cid_len;
618
619 // length of inner plaintext
620 MBEDTLS_PUT_UINT16_BE(ad_len_field, cur, 0);
621 cur += 2;
622 } else
623 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
624 {
625 MBEDTLS_PUT_UINT16_BE(ad_len_field, cur, 0);
626 cur += 2;
627 }
628
629 *add_data_len = cur - add_data;
630 }
631
632 #if defined(MBEDTLS_GCM_C) || \
633 defined(MBEDTLS_CCM_C) || \
634 defined(MBEDTLS_CHACHAPOLY_C)
635 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_transform_aead_dynamic_iv_is_explicit(mbedtls_ssl_transform const * transform)636 static int ssl_transform_aead_dynamic_iv_is_explicit(
637 mbedtls_ssl_transform const *transform)
638 {
639 return transform->ivlen != transform->fixed_ivlen;
640 }
641
642 /* Compute IV := ( fixed_iv || 0 ) XOR ( 0 || dynamic_IV )
643 *
644 * Concretely, this occurs in two variants:
645 *
646 * a) Fixed and dynamic IV lengths add up to total IV length, giving
647 * IV = fixed_iv || dynamic_iv
648 *
649 * This variant is used in TLS 1.2 when used with GCM or CCM.
650 *
651 * b) Fixed IV lengths matches total IV length, giving
652 * IV = fixed_iv XOR ( 0 || dynamic_iv )
653 *
654 * This variant occurs in TLS 1.3 and for TLS 1.2 when using ChaChaPoly.
655 *
656 * See also the documentation of mbedtls_ssl_transform.
657 *
658 * This function has the precondition that
659 *
660 * dst_iv_len >= max( fixed_iv_len, dynamic_iv_len )
661 *
662 * which has to be ensured by the caller. If this precondition
663 * violated, the behavior of this function is undefined.
664 */
ssl_build_record_nonce(unsigned char * dst_iv,size_t dst_iv_len,unsigned char const * fixed_iv,size_t fixed_iv_len,unsigned char const * dynamic_iv,size_t dynamic_iv_len)665 static void ssl_build_record_nonce(unsigned char *dst_iv,
666 size_t dst_iv_len,
667 unsigned char const *fixed_iv,
668 size_t fixed_iv_len,
669 unsigned char const *dynamic_iv,
670 size_t dynamic_iv_len)
671 {
672 /* Start with Fixed IV || 0 */
673 memset(dst_iv, 0, dst_iv_len);
674 memcpy(dst_iv, fixed_iv, fixed_iv_len);
675
676 dst_iv += dst_iv_len - dynamic_iv_len;
677 mbedtls_xor(dst_iv, dst_iv, dynamic_iv, dynamic_iv_len);
678 }
679 #endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C || MBEDTLS_CHACHAPOLY_C */
680
mbedtls_ssl_encrypt_buf(mbedtls_ssl_context * ssl,mbedtls_ssl_transform * transform,mbedtls_record * rec,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng)681 int mbedtls_ssl_encrypt_buf(mbedtls_ssl_context *ssl,
682 mbedtls_ssl_transform *transform,
683 mbedtls_record *rec,
684 int (*f_rng)(void *, unsigned char *, size_t),
685 void *p_rng)
686 {
687 mbedtls_ssl_mode_t ssl_mode;
688 int auth_done = 0;
689 unsigned char *data;
690 /* For an explanation of the additional data length see
691 * the description of ssl_extract_add_data_from_record().
692 */
693 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
694 unsigned char add_data[23 + MBEDTLS_SSL_CID_OUT_LEN_MAX];
695 #else
696 unsigned char add_data[13];
697 #endif
698 size_t add_data_len;
699 size_t post_avail;
700
701 /* The SSL context is only used for debugging purposes! */
702 #if !defined(MBEDTLS_DEBUG_C)
703 ssl = NULL; /* make sure we don't use it except for debug */
704 ((void) ssl);
705 #endif
706
707 /* The PRNG is used for dynamic IV generation that's used
708 * for CBC transformations in TLS 1.2. */
709 #if !(defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) && \
710 defined(MBEDTLS_SSL_PROTO_TLS1_2))
711 ((void) f_rng);
712 ((void) p_rng);
713 #endif
714
715 MBEDTLS_SSL_DEBUG_MSG(2, ("=> encrypt buf"));
716
717 if (transform == NULL) {
718 MBEDTLS_SSL_DEBUG_MSG(1, ("no transform provided to encrypt_buf"));
719 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
720 }
721 if (rec == NULL
722 || rec->buf == NULL
723 || rec->buf_len < rec->data_offset
724 || rec->buf_len - rec->data_offset < rec->data_len
725 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
726 || rec->cid_len != 0
727 #endif
728 ) {
729 MBEDTLS_SSL_DEBUG_MSG(1, ("bad record structure provided to encrypt_buf"));
730 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
731 }
732
733 ssl_mode = mbedtls_ssl_get_mode_from_transform(transform);
734
735 data = rec->buf + rec->data_offset;
736 post_avail = rec->buf_len - (rec->data_len + rec->data_offset);
737 MBEDTLS_SSL_DEBUG_BUF(4, "before encrypt: output payload",
738 data, rec->data_len);
739
740 if (rec->data_len > MBEDTLS_SSL_OUT_CONTENT_LEN) {
741 MBEDTLS_SSL_DEBUG_MSG(1, ("Record content %" MBEDTLS_PRINTF_SIZET
742 " too large, maximum %" MBEDTLS_PRINTF_SIZET,
743 rec->data_len,
744 (size_t) MBEDTLS_SSL_OUT_CONTENT_LEN));
745 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
746 }
747
748 /* The following two code paths implement the (D)TLSInnerPlaintext
749 * structure present in TLS 1.3 and DTLS 1.2 + CID.
750 *
751 * See ssl_build_inner_plaintext() for more information.
752 *
753 * Note that this changes `rec->data_len`, and hence
754 * `post_avail` needs to be recalculated afterwards.
755 *
756 * Note also that the two code paths cannot occur simultaneously
757 * since they apply to different versions of the protocol. There
758 * is hence no risk of double-addition of the inner plaintext.
759 */
760 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
761 if (transform->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
762 size_t padding =
763 ssl_compute_padding_length(rec->data_len,
764 MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY);
765 if (ssl_build_inner_plaintext(data,
766 &rec->data_len,
767 post_avail,
768 rec->type,
769 padding) != 0) {
770 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
771 }
772
773 rec->type = MBEDTLS_SSL_MSG_APPLICATION_DATA;
774 }
775 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
776
777 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
778 /*
779 * Add CID information
780 */
781 rec->cid_len = transform->out_cid_len;
782 memcpy(rec->cid, transform->out_cid, transform->out_cid_len);
783 MBEDTLS_SSL_DEBUG_BUF(3, "CID", rec->cid, rec->cid_len);
784
785 if (rec->cid_len != 0) {
786 size_t padding =
787 ssl_compute_padding_length(rec->data_len,
788 MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY);
789 /*
790 * Wrap plaintext into DTLSInnerPlaintext structure.
791 * See ssl_build_inner_plaintext() for more information.
792 *
793 * Note that this changes `rec->data_len`, and hence
794 * `post_avail` needs to be recalculated afterwards.
795 */
796 if (ssl_build_inner_plaintext(data,
797 &rec->data_len,
798 post_avail,
799 rec->type,
800 padding) != 0) {
801 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
802 }
803
804 rec->type = MBEDTLS_SSL_MSG_CID;
805 }
806 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
807
808 post_avail = rec->buf_len - (rec->data_len + rec->data_offset);
809
810 /*
811 * Add MAC before if needed
812 */
813 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
814 if (ssl_mode == MBEDTLS_SSL_MODE_STREAM ||
815 ssl_mode == MBEDTLS_SSL_MODE_CBC) {
816 if (post_avail < transform->maclen) {
817 MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough"));
818 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
819 }
820 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
821 unsigned char mac[MBEDTLS_SSL_MAC_ADD];
822 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
823 #if defined(MBEDTLS_USE_PSA_CRYPTO)
824 psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
825 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
826 size_t sign_mac_length = 0;
827 #endif /* MBEDTLS_USE_PSA_CRYPTO */
828
829 ssl_extract_add_data_from_record(add_data, &add_data_len, rec,
830 transform->tls_version,
831 transform->taglen);
832
833 #if defined(MBEDTLS_USE_PSA_CRYPTO)
834 status = psa_mac_sign_setup(&operation, transform->psa_mac_enc,
835 transform->psa_mac_alg);
836 if (status != PSA_SUCCESS) {
837 goto hmac_failed_etm_disabled;
838 }
839
840 status = psa_mac_update(&operation, add_data, add_data_len);
841 if (status != PSA_SUCCESS) {
842 goto hmac_failed_etm_disabled;
843 }
844
845 status = psa_mac_update(&operation, data, rec->data_len);
846 if (status != PSA_SUCCESS) {
847 goto hmac_failed_etm_disabled;
848 }
849
850 status = psa_mac_sign_finish(&operation, mac, MBEDTLS_SSL_MAC_ADD,
851 &sign_mac_length);
852 if (status != PSA_SUCCESS) {
853 goto hmac_failed_etm_disabled;
854 }
855 #else
856 ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, add_data,
857 add_data_len);
858 if (ret != 0) {
859 goto hmac_failed_etm_disabled;
860 }
861 ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, data, rec->data_len);
862 if (ret != 0) {
863 goto hmac_failed_etm_disabled;
864 }
865 ret = mbedtls_md_hmac_finish(&transform->md_ctx_enc, mac);
866 if (ret != 0) {
867 goto hmac_failed_etm_disabled;
868 }
869 ret = mbedtls_md_hmac_reset(&transform->md_ctx_enc);
870 if (ret != 0) {
871 goto hmac_failed_etm_disabled;
872 }
873 #endif /* MBEDTLS_USE_PSA_CRYPTO */
874
875 memcpy(data + rec->data_len, mac, transform->maclen);
876 #endif
877
878 MBEDTLS_SSL_DEBUG_BUF(4, "computed mac", data + rec->data_len,
879 transform->maclen);
880
881 rec->data_len += transform->maclen;
882 post_avail -= transform->maclen;
883 auth_done++;
884
885 hmac_failed_etm_disabled:
886 mbedtls_platform_zeroize(mac, transform->maclen);
887 #if defined(MBEDTLS_USE_PSA_CRYPTO)
888 ret = PSA_TO_MBEDTLS_ERR(status);
889 status = psa_mac_abort(&operation);
890 if (ret == 0 && status != PSA_SUCCESS) {
891 ret = PSA_TO_MBEDTLS_ERR(status);
892 }
893 #endif /* MBEDTLS_USE_PSA_CRYPTO */
894 if (ret != 0) {
895 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_md_hmac_xxx", ret);
896 return ret;
897 }
898 }
899 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
900
901 /*
902 * Encrypt
903 */
904 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_STREAM)
905 if (ssl_mode == MBEDTLS_SSL_MODE_STREAM) {
906 MBEDTLS_SSL_DEBUG_MSG(3, ("before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", "
907 "including %d bytes of padding",
908 rec->data_len, 0));
909
910 /* The only supported stream cipher is "NULL",
911 * so there's nothing to do here.*/
912 } else
913 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_STREAM */
914
915 #if defined(MBEDTLS_GCM_C) || \
916 defined(MBEDTLS_CCM_C) || \
917 defined(MBEDTLS_CHACHAPOLY_C)
918 if (ssl_mode == MBEDTLS_SSL_MODE_AEAD) {
919 unsigned char iv[12];
920 unsigned char *dynamic_iv;
921 size_t dynamic_iv_len;
922 int dynamic_iv_is_explicit =
923 ssl_transform_aead_dynamic_iv_is_explicit(transform);
924 #if defined(MBEDTLS_USE_PSA_CRYPTO)
925 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
926 #endif /* MBEDTLS_USE_PSA_CRYPTO */
927 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
928
929 /* Check that there's space for the authentication tag. */
930 if (post_avail < transform->taglen) {
931 MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough"));
932 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
933 }
934
935 /*
936 * Build nonce for AEAD encryption.
937 *
938 * Note: In the case of CCM and GCM in TLS 1.2, the dynamic
939 * part of the IV is prepended to the ciphertext and
940 * can be chosen freely - in particular, it need not
941 * agree with the record sequence number.
942 * However, since ChaChaPoly as well as all AEAD modes
943 * in TLS 1.3 use the record sequence number as the
944 * dynamic part of the nonce, we uniformly use the
945 * record sequence number here in all cases.
946 */
947 dynamic_iv = rec->ctr;
948 dynamic_iv_len = sizeof(rec->ctr);
949
950 ssl_build_record_nonce(iv, sizeof(iv),
951 transform->iv_enc,
952 transform->fixed_ivlen,
953 dynamic_iv,
954 dynamic_iv_len);
955
956 /*
957 * Build additional data for AEAD encryption.
958 * This depends on the TLS version.
959 */
960 ssl_extract_add_data_from_record(add_data, &add_data_len, rec,
961 transform->tls_version,
962 transform->taglen);
963
964 MBEDTLS_SSL_DEBUG_BUF(4, "IV used (internal)",
965 iv, transform->ivlen);
966 MBEDTLS_SSL_DEBUG_BUF(4, "IV used (transmitted)",
967 dynamic_iv,
968 dynamic_iv_is_explicit ? dynamic_iv_len : 0);
969 MBEDTLS_SSL_DEBUG_BUF(4, "additional data used for AEAD",
970 add_data, add_data_len);
971 MBEDTLS_SSL_DEBUG_MSG(3, ("before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", "
972 "including 0 bytes of padding",
973 rec->data_len));
974
975 /*
976 * Encrypt and authenticate
977 */
978 #if defined(MBEDTLS_USE_PSA_CRYPTO)
979 status = psa_aead_encrypt(transform->psa_key_enc,
980 transform->psa_alg,
981 iv, transform->ivlen,
982 add_data, add_data_len,
983 data, rec->data_len,
984 data, rec->buf_len - (data - rec->buf),
985 &rec->data_len);
986
987 if (status != PSA_SUCCESS) {
988 ret = PSA_TO_MBEDTLS_ERR(status);
989 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_encrypt_buf", ret);
990 return ret;
991 }
992 #else
993 if ((ret = mbedtls_cipher_auth_encrypt_ext(&transform->cipher_ctx_enc,
994 iv, transform->ivlen,
995 add_data, add_data_len,
996 data, rec->data_len, /* src */
997 data, rec->buf_len - (data - rec->buf), /* dst */
998 &rec->data_len,
999 transform->taglen)) != 0) {
1000 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_auth_encrypt_ext", ret);
1001 return ret;
1002 }
1003 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1004
1005 MBEDTLS_SSL_DEBUG_BUF(4, "after encrypt: tag",
1006 data + rec->data_len - transform->taglen,
1007 transform->taglen);
1008 /* Account for authentication tag. */
1009 post_avail -= transform->taglen;
1010
1011 /*
1012 * Prefix record content with dynamic IV in case it is explicit.
1013 */
1014 if (dynamic_iv_is_explicit != 0) {
1015 if (rec->data_offset < dynamic_iv_len) {
1016 MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough"));
1017 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
1018 }
1019
1020 memcpy(data - dynamic_iv_len, dynamic_iv, dynamic_iv_len);
1021 rec->data_offset -= dynamic_iv_len;
1022 rec->data_len += dynamic_iv_len;
1023 }
1024
1025 auth_done++;
1026 } else
1027 #endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C || MBEDTLS_CHACHAPOLY_C */
1028 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC)
1029 if (ssl_mode == MBEDTLS_SSL_MODE_CBC ||
1030 ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) {
1031 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1032 size_t padlen, i;
1033 size_t olen;
1034 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1035 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
1036 size_t part_len;
1037 psa_cipher_operation_t cipher_op = PSA_CIPHER_OPERATION_INIT;
1038 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1039
1040 /* Currently we're always using minimal padding
1041 * (up to 255 bytes would be allowed). */
1042 padlen = transform->ivlen - (rec->data_len + 1) % transform->ivlen;
1043 if (padlen == transform->ivlen) {
1044 padlen = 0;
1045 }
1046
1047 /* Check there's enough space in the buffer for the padding. */
1048 if (post_avail < padlen + 1) {
1049 MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough"));
1050 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
1051 }
1052
1053 for (i = 0; i <= padlen; i++) {
1054 data[rec->data_len + i] = (unsigned char) padlen;
1055 }
1056
1057 rec->data_len += padlen + 1;
1058 post_avail -= padlen + 1;
1059
1060 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
1061 /*
1062 * Prepend per-record IV for block cipher in TLS v1.2 as per
1063 * Method 1 (6.2.3.2. in RFC4346 and RFC5246)
1064 */
1065 if (f_rng == NULL) {
1066 MBEDTLS_SSL_DEBUG_MSG(1, ("No PRNG provided to encrypt_record routine"));
1067 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1068 }
1069
1070 if (rec->data_offset < transform->ivlen) {
1071 MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough"));
1072 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
1073 }
1074
1075 /*
1076 * Generate IV
1077 */
1078 ret = f_rng(p_rng, transform->iv_enc, transform->ivlen);
1079 if (ret != 0) {
1080 return ret;
1081 }
1082
1083 memcpy(data - transform->ivlen, transform->iv_enc, transform->ivlen);
1084 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
1085
1086 MBEDTLS_SSL_DEBUG_MSG(3, ("before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", "
1087 "including %"
1088 MBEDTLS_PRINTF_SIZET
1089 " bytes of IV and %" MBEDTLS_PRINTF_SIZET " bytes of padding",
1090 rec->data_len, transform->ivlen,
1091 padlen + 1));
1092
1093 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1094 status = psa_cipher_encrypt_setup(&cipher_op,
1095 transform->psa_key_enc, transform->psa_alg);
1096
1097 if (status != PSA_SUCCESS) {
1098 ret = PSA_TO_MBEDTLS_ERR(status);
1099 MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_encrypt_setup", ret);
1100 return ret;
1101 }
1102
1103 status = psa_cipher_set_iv(&cipher_op, transform->iv_enc, transform->ivlen);
1104
1105 if (status != PSA_SUCCESS) {
1106 ret = PSA_TO_MBEDTLS_ERR(status);
1107 MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_set_iv", ret);
1108 return ret;
1109
1110 }
1111
1112 status = psa_cipher_update(&cipher_op,
1113 data, rec->data_len,
1114 data, rec->data_len, &olen);
1115
1116 if (status != PSA_SUCCESS) {
1117 ret = PSA_TO_MBEDTLS_ERR(status);
1118 MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_update", ret);
1119 return ret;
1120
1121 }
1122
1123 status = psa_cipher_finish(&cipher_op,
1124 data + olen, rec->data_len - olen,
1125 &part_len);
1126
1127 if (status != PSA_SUCCESS) {
1128 ret = PSA_TO_MBEDTLS_ERR(status);
1129 MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_finish", ret);
1130 return ret;
1131
1132 }
1133
1134 olen += part_len;
1135 #else
1136 if ((ret = mbedtls_cipher_crypt(&transform->cipher_ctx_enc,
1137 transform->iv_enc,
1138 transform->ivlen,
1139 data, rec->data_len,
1140 data, &olen)) != 0) {
1141 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_crypt", ret);
1142 return ret;
1143 }
1144 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1145
1146 if (rec->data_len != olen) {
1147 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
1148 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1149 }
1150
1151 data -= transform->ivlen;
1152 rec->data_offset -= transform->ivlen;
1153 rec->data_len += transform->ivlen;
1154
1155 #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
1156 if (auth_done == 0) {
1157 unsigned char mac[MBEDTLS_SSL_MAC_ADD];
1158 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1159 psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
1160 size_t sign_mac_length = 0;
1161 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1162
1163 /* MAC(MAC_write_key, add_data, IV, ENC(content + padding + padding_length))
1164 */
1165
1166 if (post_avail < transform->maclen) {
1167 MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough"));
1168 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
1169 }
1170
1171 ssl_extract_add_data_from_record(add_data, &add_data_len,
1172 rec, transform->tls_version,
1173 transform->taglen);
1174
1175 MBEDTLS_SSL_DEBUG_MSG(3, ("using encrypt then mac"));
1176 MBEDTLS_SSL_DEBUG_BUF(4, "MAC'd meta-data", add_data,
1177 add_data_len);
1178 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1179 status = psa_mac_sign_setup(&operation, transform->psa_mac_enc,
1180 transform->psa_mac_alg);
1181 if (status != PSA_SUCCESS) {
1182 goto hmac_failed_etm_enabled;
1183 }
1184
1185 status = psa_mac_update(&operation, add_data, add_data_len);
1186 if (status != PSA_SUCCESS) {
1187 goto hmac_failed_etm_enabled;
1188 }
1189
1190 status = psa_mac_update(&operation, data, rec->data_len);
1191 if (status != PSA_SUCCESS) {
1192 goto hmac_failed_etm_enabled;
1193 }
1194
1195 status = psa_mac_sign_finish(&operation, mac, MBEDTLS_SSL_MAC_ADD,
1196 &sign_mac_length);
1197 if (status != PSA_SUCCESS) {
1198 goto hmac_failed_etm_enabled;
1199 }
1200 #else
1201
1202 ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, add_data,
1203 add_data_len);
1204 if (ret != 0) {
1205 goto hmac_failed_etm_enabled;
1206 }
1207 ret = mbedtls_md_hmac_update(&transform->md_ctx_enc,
1208 data, rec->data_len);
1209 if (ret != 0) {
1210 goto hmac_failed_etm_enabled;
1211 }
1212 ret = mbedtls_md_hmac_finish(&transform->md_ctx_enc, mac);
1213 if (ret != 0) {
1214 goto hmac_failed_etm_enabled;
1215 }
1216 ret = mbedtls_md_hmac_reset(&transform->md_ctx_enc);
1217 if (ret != 0) {
1218 goto hmac_failed_etm_enabled;
1219 }
1220 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1221
1222 memcpy(data + rec->data_len, mac, transform->maclen);
1223
1224 rec->data_len += transform->maclen;
1225 post_avail -= transform->maclen;
1226 auth_done++;
1227
1228 hmac_failed_etm_enabled:
1229 mbedtls_platform_zeroize(mac, transform->maclen);
1230 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1231 ret = PSA_TO_MBEDTLS_ERR(status);
1232 status = psa_mac_abort(&operation);
1233 if (ret == 0 && status != PSA_SUCCESS) {
1234 ret = PSA_TO_MBEDTLS_ERR(status);
1235 }
1236 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1237 if (ret != 0) {
1238 MBEDTLS_SSL_DEBUG_RET(1, "HMAC calculation failed", ret);
1239 return ret;
1240 }
1241 }
1242 #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
1243 } else
1244 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC) */
1245 {
1246 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
1247 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1248 }
1249
1250 /* Make extra sure authentication was performed, exactly once */
1251 if (auth_done != 1) {
1252 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
1253 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1254 }
1255
1256 MBEDTLS_SSL_DEBUG_MSG(2, ("<= encrypt buf"));
1257
1258 return 0;
1259 }
1260
mbedtls_ssl_decrypt_buf(mbedtls_ssl_context const * ssl,mbedtls_ssl_transform * transform,mbedtls_record * rec)1261 int mbedtls_ssl_decrypt_buf(mbedtls_ssl_context const *ssl,
1262 mbedtls_ssl_transform *transform,
1263 mbedtls_record *rec)
1264 {
1265 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) || defined(MBEDTLS_CIPHER_MODE_AEAD)
1266 size_t olen;
1267 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC || MBEDTLS_CIPHER_MODE_AEAD */
1268 mbedtls_ssl_mode_t ssl_mode;
1269 int ret;
1270
1271 int auth_done = 0;
1272 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
1273 size_t padlen = 0, correct = 1;
1274 #endif
1275 unsigned char *data;
1276 /* For an explanation of the additional data length see
1277 * the description of ssl_extract_add_data_from_record().
1278 */
1279 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1280 unsigned char add_data[23 + MBEDTLS_SSL_CID_IN_LEN_MAX];
1281 #else
1282 unsigned char add_data[13];
1283 #endif
1284 size_t add_data_len;
1285
1286 #if !defined(MBEDTLS_DEBUG_C)
1287 ssl = NULL; /* make sure we don't use it except for debug */
1288 ((void) ssl);
1289 #endif
1290
1291 MBEDTLS_SSL_DEBUG_MSG(2, ("=> decrypt buf"));
1292 if (rec == NULL ||
1293 rec->buf == NULL ||
1294 rec->buf_len < rec->data_offset ||
1295 rec->buf_len - rec->data_offset < rec->data_len) {
1296 MBEDTLS_SSL_DEBUG_MSG(1, ("bad record structure provided to decrypt_buf"));
1297 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1298 }
1299
1300 data = rec->buf + rec->data_offset;
1301 ssl_mode = mbedtls_ssl_get_mode_from_transform(transform);
1302
1303 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1304 /*
1305 * Match record's CID with incoming CID.
1306 */
1307 if (rec->cid_len != transform->in_cid_len ||
1308 memcmp(rec->cid, transform->in_cid, rec->cid_len) != 0) {
1309 return MBEDTLS_ERR_SSL_UNEXPECTED_CID;
1310 }
1311 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
1312
1313 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_STREAM)
1314 if (ssl_mode == MBEDTLS_SSL_MODE_STREAM) {
1315 /* The only supported stream cipher is "NULL",
1316 * so there's nothing to do here.*/
1317 } else
1318 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_STREAM */
1319 #if defined(MBEDTLS_GCM_C) || \
1320 defined(MBEDTLS_CCM_C) || \
1321 defined(MBEDTLS_CHACHAPOLY_C)
1322 if (ssl_mode == MBEDTLS_SSL_MODE_AEAD) {
1323 unsigned char iv[12];
1324 unsigned char *dynamic_iv;
1325 size_t dynamic_iv_len;
1326 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1327 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
1328 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1329
1330 /*
1331 * Extract dynamic part of nonce for AEAD decryption.
1332 *
1333 * Note: In the case of CCM and GCM in TLS 1.2, the dynamic
1334 * part of the IV is prepended to the ciphertext and
1335 * can be chosen freely - in particular, it need not
1336 * agree with the record sequence number.
1337 */
1338 dynamic_iv_len = sizeof(rec->ctr);
1339 if (ssl_transform_aead_dynamic_iv_is_explicit(transform) == 1) {
1340 if (rec->data_len < dynamic_iv_len) {
1341 MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET
1342 " ) < explicit_iv_len (%" MBEDTLS_PRINTF_SIZET ") ",
1343 rec->data_len,
1344 dynamic_iv_len));
1345 return MBEDTLS_ERR_SSL_INVALID_MAC;
1346 }
1347 dynamic_iv = data;
1348
1349 data += dynamic_iv_len;
1350 rec->data_offset += dynamic_iv_len;
1351 rec->data_len -= dynamic_iv_len;
1352 } else {
1353 dynamic_iv = rec->ctr;
1354 }
1355
1356 /* Check that there's space for the authentication tag. */
1357 if (rec->data_len < transform->taglen) {
1358 MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET
1359 ") < taglen (%" MBEDTLS_PRINTF_SIZET ") ",
1360 rec->data_len,
1361 transform->taglen));
1362 return MBEDTLS_ERR_SSL_INVALID_MAC;
1363 }
1364 rec->data_len -= transform->taglen;
1365
1366 /*
1367 * Prepare nonce from dynamic and static parts.
1368 */
1369 ssl_build_record_nonce(iv, sizeof(iv),
1370 transform->iv_dec,
1371 transform->fixed_ivlen,
1372 dynamic_iv,
1373 dynamic_iv_len);
1374
1375 /*
1376 * Build additional data for AEAD encryption.
1377 * This depends on the TLS version.
1378 */
1379 ssl_extract_add_data_from_record(add_data, &add_data_len, rec,
1380 transform->tls_version,
1381 transform->taglen);
1382 MBEDTLS_SSL_DEBUG_BUF(4, "additional data used for AEAD",
1383 add_data, add_data_len);
1384
1385 /* Because of the check above, we know that there are
1386 * explicit_iv_len Bytes preceding data, and taglen
1387 * bytes following data + data_len. This justifies
1388 * the debug message and the invocation of
1389 * mbedtls_cipher_auth_decrypt_ext() below. */
1390
1391 MBEDTLS_SSL_DEBUG_BUF(4, "IV used", iv, transform->ivlen);
1392 MBEDTLS_SSL_DEBUG_BUF(4, "TAG used", data + rec->data_len,
1393 transform->taglen);
1394
1395 /*
1396 * Decrypt and authenticate
1397 */
1398 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1399 status = psa_aead_decrypt(transform->psa_key_dec,
1400 transform->psa_alg,
1401 iv, transform->ivlen,
1402 add_data, add_data_len,
1403 data, rec->data_len + transform->taglen,
1404 data, rec->buf_len - (data - rec->buf),
1405 &olen);
1406
1407 if (status != PSA_SUCCESS) {
1408 ret = PSA_TO_MBEDTLS_ERR(status);
1409 MBEDTLS_SSL_DEBUG_RET(1, "psa_aead_decrypt", ret);
1410 return ret;
1411 }
1412 #else
1413 if ((ret = mbedtls_cipher_auth_decrypt_ext(&transform->cipher_ctx_dec,
1414 iv, transform->ivlen,
1415 add_data, add_data_len,
1416 data, rec->data_len + transform->taglen, /* src */
1417 data, rec->buf_len - (data - rec->buf), &olen, /* dst */
1418 transform->taglen)) != 0) {
1419 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_auth_decrypt_ext", ret);
1420
1421 if (ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED) {
1422 return MBEDTLS_ERR_SSL_INVALID_MAC;
1423 }
1424
1425 return ret;
1426 }
1427 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1428
1429 auth_done++;
1430
1431 /* Double-check that AEAD decryption doesn't change content length. */
1432 if (olen != rec->data_len) {
1433 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
1434 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1435 }
1436 } else
1437 #endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C */
1438 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC)
1439 if (ssl_mode == MBEDTLS_SSL_MODE_CBC ||
1440 ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) {
1441 size_t minlen = 0;
1442 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1443 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
1444 size_t part_len;
1445 psa_cipher_operation_t cipher_op = PSA_CIPHER_OPERATION_INIT;
1446 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1447
1448 /*
1449 * Check immediate ciphertext sanity
1450 */
1451 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
1452 /* The ciphertext is prefixed with the CBC IV. */
1453 minlen += transform->ivlen;
1454 #endif
1455
1456 /* Size considerations:
1457 *
1458 * - The CBC cipher text must not be empty and hence
1459 * at least of size transform->ivlen.
1460 *
1461 * Together with the potential IV-prefix, this explains
1462 * the first of the two checks below.
1463 *
1464 * - The record must contain a MAC, either in plain or
1465 * encrypted, depending on whether Encrypt-then-MAC
1466 * is used or not.
1467 * - If it is, the message contains the IV-prefix,
1468 * the CBC ciphertext, and the MAC.
1469 * - If it is not, the padded plaintext, and hence
1470 * the CBC ciphertext, has at least length maclen + 1
1471 * because there is at least the padding length byte.
1472 *
1473 * As the CBC ciphertext is not empty, both cases give the
1474 * lower bound minlen + maclen + 1 on the record size, which
1475 * we test for in the second check below.
1476 */
1477 if (rec->data_len < minlen + transform->ivlen ||
1478 rec->data_len < minlen + transform->maclen + 1) {
1479 MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET
1480 ") < max( ivlen(%" MBEDTLS_PRINTF_SIZET
1481 "), maclen (%" MBEDTLS_PRINTF_SIZET ") "
1482 "+ 1 ) ( + expl IV )",
1483 rec->data_len,
1484 transform->ivlen,
1485 transform->maclen));
1486 return MBEDTLS_ERR_SSL_INVALID_MAC;
1487 }
1488
1489 /*
1490 * Authenticate before decrypt if enabled
1491 */
1492 #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
1493 if (ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) {
1494 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1495 psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
1496 #else
1497 unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
1498 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1499
1500 MBEDTLS_SSL_DEBUG_MSG(3, ("using encrypt then mac"));
1501
1502 /* Update data_len in tandem with add_data.
1503 *
1504 * The subtraction is safe because of the previous check
1505 * data_len >= minlen + maclen + 1.
1506 *
1507 * Afterwards, we know that data + data_len is followed by at
1508 * least maclen Bytes, which justifies the call to
1509 * mbedtls_ct_memcmp() below.
1510 *
1511 * Further, we still know that data_len > minlen */
1512 rec->data_len -= transform->maclen;
1513 ssl_extract_add_data_from_record(add_data, &add_data_len, rec,
1514 transform->tls_version,
1515 transform->taglen);
1516
1517 /* Calculate expected MAC. */
1518 MBEDTLS_SSL_DEBUG_BUF(4, "MAC'd meta-data", add_data,
1519 add_data_len);
1520 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1521 status = psa_mac_verify_setup(&operation, transform->psa_mac_dec,
1522 transform->psa_mac_alg);
1523 if (status != PSA_SUCCESS) {
1524 goto hmac_failed_etm_enabled;
1525 }
1526
1527 status = psa_mac_update(&operation, add_data, add_data_len);
1528 if (status != PSA_SUCCESS) {
1529 goto hmac_failed_etm_enabled;
1530 }
1531
1532 status = psa_mac_update(&operation, data, rec->data_len);
1533 if (status != PSA_SUCCESS) {
1534 goto hmac_failed_etm_enabled;
1535 }
1536
1537 /* Compare expected MAC with MAC at the end of the record. */
1538 status = psa_mac_verify_finish(&operation, data + rec->data_len,
1539 transform->maclen);
1540 if (status != PSA_SUCCESS) {
1541 goto hmac_failed_etm_enabled;
1542 }
1543 #else
1544 ret = mbedtls_md_hmac_update(&transform->md_ctx_dec, add_data,
1545 add_data_len);
1546 if (ret != 0) {
1547 goto hmac_failed_etm_enabled;
1548 }
1549 ret = mbedtls_md_hmac_update(&transform->md_ctx_dec,
1550 data, rec->data_len);
1551 if (ret != 0) {
1552 goto hmac_failed_etm_enabled;
1553 }
1554 ret = mbedtls_md_hmac_finish(&transform->md_ctx_dec, mac_expect);
1555 if (ret != 0) {
1556 goto hmac_failed_etm_enabled;
1557 }
1558 ret = mbedtls_md_hmac_reset(&transform->md_ctx_dec);
1559 if (ret != 0) {
1560 goto hmac_failed_etm_enabled;
1561 }
1562
1563 MBEDTLS_SSL_DEBUG_BUF(4, "message mac", data + rec->data_len,
1564 transform->maclen);
1565 MBEDTLS_SSL_DEBUG_BUF(4, "expected mac", mac_expect,
1566 transform->maclen);
1567
1568 /* Compare expected MAC with MAC at the end of the record. */
1569 if (mbedtls_ct_memcmp(data + rec->data_len, mac_expect,
1570 transform->maclen) != 0) {
1571 MBEDTLS_SSL_DEBUG_MSG(1, ("message mac does not match"));
1572 ret = MBEDTLS_ERR_SSL_INVALID_MAC;
1573 goto hmac_failed_etm_enabled;
1574 }
1575 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1576 auth_done++;
1577
1578 hmac_failed_etm_enabled:
1579 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1580 ret = PSA_TO_MBEDTLS_ERR(status);
1581 status = psa_mac_abort(&operation);
1582 if (ret == 0 && status != PSA_SUCCESS) {
1583 ret = PSA_TO_MBEDTLS_ERR(status);
1584 }
1585 #else
1586 mbedtls_platform_zeroize(mac_expect, transform->maclen);
1587 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1588 if (ret != 0) {
1589 if (ret != MBEDTLS_ERR_SSL_INVALID_MAC) {
1590 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_hmac_xxx", ret);
1591 }
1592 return ret;
1593 }
1594 }
1595 #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
1596
1597 /*
1598 * Check length sanity
1599 */
1600
1601 /* We know from above that data_len > minlen >= 0,
1602 * so the following check in particular implies that
1603 * data_len >= minlen + ivlen ( = minlen or 2 * minlen ). */
1604 if (rec->data_len % transform->ivlen != 0) {
1605 MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET
1606 ") %% ivlen (%" MBEDTLS_PRINTF_SIZET ") != 0",
1607 rec->data_len, transform->ivlen));
1608 return MBEDTLS_ERR_SSL_INVALID_MAC;
1609 }
1610
1611 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
1612 /*
1613 * Initialize for prepended IV for block cipher in TLS v1.2
1614 */
1615 /* Safe because data_len >= minlen + ivlen = 2 * ivlen. */
1616 memcpy(transform->iv_dec, data, transform->ivlen);
1617
1618 data += transform->ivlen;
1619 rec->data_offset += transform->ivlen;
1620 rec->data_len -= transform->ivlen;
1621 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
1622
1623 /* We still have data_len % ivlen == 0 and data_len >= ivlen here. */
1624
1625 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1626 status = psa_cipher_decrypt_setup(&cipher_op,
1627 transform->psa_key_dec, transform->psa_alg);
1628
1629 if (status != PSA_SUCCESS) {
1630 ret = PSA_TO_MBEDTLS_ERR(status);
1631 MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_decrypt_setup", ret);
1632 return ret;
1633 }
1634
1635 status = psa_cipher_set_iv(&cipher_op, transform->iv_dec, transform->ivlen);
1636
1637 if (status != PSA_SUCCESS) {
1638 ret = PSA_TO_MBEDTLS_ERR(status);
1639 MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_set_iv", ret);
1640 return ret;
1641 }
1642
1643 status = psa_cipher_update(&cipher_op,
1644 data, rec->data_len,
1645 data, rec->data_len, &olen);
1646
1647 if (status != PSA_SUCCESS) {
1648 ret = PSA_TO_MBEDTLS_ERR(status);
1649 MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_update", ret);
1650 return ret;
1651 }
1652
1653 status = psa_cipher_finish(&cipher_op,
1654 data + olen, rec->data_len - olen,
1655 &part_len);
1656
1657 if (status != PSA_SUCCESS) {
1658 ret = PSA_TO_MBEDTLS_ERR(status);
1659 MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_finish", ret);
1660 return ret;
1661 }
1662
1663 olen += part_len;
1664 #else
1665
1666 if ((ret = mbedtls_cipher_crypt(&transform->cipher_ctx_dec,
1667 transform->iv_dec, transform->ivlen,
1668 data, rec->data_len, data, &olen)) != 0) {
1669 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_crypt", ret);
1670 return ret;
1671 }
1672 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1673
1674 /* Double-check that length hasn't changed during decryption. */
1675 if (rec->data_len != olen) {
1676 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
1677 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1678 }
1679
1680 /* Safe since data_len >= minlen + maclen + 1, so after having
1681 * subtracted at most minlen and maclen up to this point,
1682 * data_len > 0 (because of data_len % ivlen == 0, it's actually
1683 * >= ivlen ). */
1684 padlen = data[rec->data_len - 1];
1685
1686 if (auth_done == 1) {
1687 const size_t mask = mbedtls_ct_size_mask_ge(
1688 rec->data_len,
1689 padlen + 1);
1690 correct &= mask;
1691 padlen &= mask;
1692 } else {
1693 #if defined(MBEDTLS_SSL_DEBUG_ALL)
1694 if (rec->data_len < transform->maclen + padlen + 1) {
1695 MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET
1696 ") < maclen (%" MBEDTLS_PRINTF_SIZET
1697 ") + padlen (%" MBEDTLS_PRINTF_SIZET ")",
1698 rec->data_len,
1699 transform->maclen,
1700 padlen + 1));
1701 }
1702 #endif
1703
1704 const size_t mask = mbedtls_ct_size_mask_ge(
1705 rec->data_len,
1706 transform->maclen + padlen + 1);
1707 correct &= mask;
1708 padlen &= mask;
1709 }
1710
1711 padlen++;
1712
1713 /* Regardless of the validity of the padding,
1714 * we have data_len >= padlen here. */
1715
1716 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
1717 /* The padding check involves a series of up to 256
1718 * consecutive memory reads at the end of the record
1719 * plaintext buffer. In order to hide the length and
1720 * validity of the padding, always perform exactly
1721 * `min(256,plaintext_len)` reads (but take into account
1722 * only the last `padlen` bytes for the padding check). */
1723 size_t pad_count = 0;
1724 volatile unsigned char * const check = data;
1725
1726 /* Index of first padding byte; it has been ensured above
1727 * that the subtraction is safe. */
1728 size_t const padding_idx = rec->data_len - padlen;
1729 size_t const num_checks = rec->data_len <= 256 ? rec->data_len : 256;
1730 size_t const start_idx = rec->data_len - num_checks;
1731 size_t idx;
1732
1733 for (idx = start_idx; idx < rec->data_len; idx++) {
1734 /* pad_count += (idx >= padding_idx) &&
1735 * (check[idx] == padlen - 1);
1736 */
1737 const size_t mask = mbedtls_ct_size_mask_ge(idx, padding_idx);
1738 const size_t equal = mbedtls_ct_size_bool_eq(check[idx],
1739 padlen - 1);
1740 pad_count += mask & equal;
1741 }
1742 correct &= mbedtls_ct_size_bool_eq(pad_count, padlen);
1743
1744 #if defined(MBEDTLS_SSL_DEBUG_ALL)
1745 if (padlen > 0 && correct == 0) {
1746 MBEDTLS_SSL_DEBUG_MSG(1, ("bad padding byte detected"));
1747 }
1748 #endif
1749 padlen &= mbedtls_ct_size_mask(correct);
1750
1751 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
1752
1753 /* If the padding was found to be invalid, padlen == 0
1754 * and the subtraction is safe. If the padding was found valid,
1755 * padlen hasn't been changed and the previous assertion
1756 * data_len >= padlen still holds. */
1757 rec->data_len -= padlen;
1758 } else
1759 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC */
1760 {
1761 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
1762 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1763 }
1764
1765 #if defined(MBEDTLS_SSL_DEBUG_ALL)
1766 MBEDTLS_SSL_DEBUG_BUF(4, "raw buffer after decryption",
1767 data, rec->data_len);
1768 #endif
1769
1770 /*
1771 * Authenticate if not done yet.
1772 * Compute the MAC regardless of the padding result (RFC4346, CBCTIME).
1773 */
1774 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
1775 if (auth_done == 0) {
1776 unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD] = { 0 };
1777 unsigned char mac_peer[MBEDTLS_SSL_MAC_ADD] = { 0 };
1778
1779 /* If the initial value of padlen was such that
1780 * data_len < maclen + padlen + 1, then padlen
1781 * got reset to 1, and the initial check
1782 * data_len >= minlen + maclen + 1
1783 * guarantees that at this point we still
1784 * have at least data_len >= maclen.
1785 *
1786 * If the initial value of padlen was such that
1787 * data_len >= maclen + padlen + 1, then we have
1788 * subtracted either padlen + 1 (if the padding was correct)
1789 * or 0 (if the padding was incorrect) since then,
1790 * hence data_len >= maclen in any case.
1791 */
1792 rec->data_len -= transform->maclen;
1793 ssl_extract_add_data_from_record(add_data, &add_data_len, rec,
1794 transform->tls_version,
1795 transform->taglen);
1796
1797 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
1798 /*
1799 * The next two sizes are the minimum and maximum values of
1800 * data_len over all padlen values.
1801 *
1802 * They're independent of padlen, since we previously did
1803 * data_len -= padlen.
1804 *
1805 * Note that max_len + maclen is never more than the buffer
1806 * length, as we previously did in_msglen -= maclen too.
1807 */
1808 const size_t max_len = rec->data_len + padlen;
1809 const size_t min_len = (max_len > 256) ? max_len - 256 : 0;
1810
1811 #if defined(MBEDTLS_USE_PSA_CRYPTO)
1812 ret = mbedtls_ct_hmac(transform->psa_mac_dec,
1813 transform->psa_mac_alg,
1814 add_data, add_data_len,
1815 data, rec->data_len, min_len, max_len,
1816 mac_expect);
1817 #else
1818 ret = mbedtls_ct_hmac(&transform->md_ctx_dec,
1819 add_data, add_data_len,
1820 data, rec->data_len, min_len, max_len,
1821 mac_expect);
1822 #endif /* MBEDTLS_USE_PSA_CRYPTO */
1823 if (ret != 0) {
1824 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ct_hmac", ret);
1825 goto hmac_failed_etm_disabled;
1826 }
1827
1828 mbedtls_ct_memcpy_offset(mac_peer, data,
1829 rec->data_len,
1830 min_len, max_len,
1831 transform->maclen);
1832 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
1833
1834 #if defined(MBEDTLS_SSL_DEBUG_ALL)
1835 MBEDTLS_SSL_DEBUG_BUF(4, "expected mac", mac_expect, transform->maclen);
1836 MBEDTLS_SSL_DEBUG_BUF(4, "message mac", mac_peer, transform->maclen);
1837 #endif
1838
1839 if (mbedtls_ct_memcmp(mac_peer, mac_expect,
1840 transform->maclen) != 0) {
1841 #if defined(MBEDTLS_SSL_DEBUG_ALL)
1842 MBEDTLS_SSL_DEBUG_MSG(1, ("message mac does not match"));
1843 #endif
1844 correct = 0;
1845 }
1846 auth_done++;
1847
1848 hmac_failed_etm_disabled:
1849 mbedtls_platform_zeroize(mac_peer, transform->maclen);
1850 mbedtls_platform_zeroize(mac_expect, transform->maclen);
1851 if (ret != 0) {
1852 return ret;
1853 }
1854 }
1855
1856 /*
1857 * Finally check the correct flag
1858 */
1859 if (correct == 0) {
1860 return MBEDTLS_ERR_SSL_INVALID_MAC;
1861 }
1862 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
1863
1864 /* Make extra sure authentication was performed, exactly once */
1865 if (auth_done != 1) {
1866 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
1867 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1868 }
1869
1870 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
1871 if (transform->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
1872 /* Remove inner padding and infer true content type. */
1873 ret = ssl_parse_inner_plaintext(data, &rec->data_len,
1874 &rec->type);
1875
1876 if (ret != 0) {
1877 return MBEDTLS_ERR_SSL_INVALID_RECORD;
1878 }
1879 }
1880 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
1881
1882 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1883 if (rec->cid_len != 0) {
1884 ret = ssl_parse_inner_plaintext(data, &rec->data_len,
1885 &rec->type);
1886 if (ret != 0) {
1887 return MBEDTLS_ERR_SSL_INVALID_RECORD;
1888 }
1889 }
1890 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
1891
1892 MBEDTLS_SSL_DEBUG_MSG(2, ("<= decrypt buf"));
1893
1894 return 0;
1895 }
1896
1897 #undef MAC_NONE
1898 #undef MAC_PLAINTEXT
1899 #undef MAC_CIPHERTEXT
1900
1901 /*
1902 * Fill the input message buffer by appending data to it.
1903 * The amount of data already fetched is in ssl->in_left.
1904 *
1905 * If we return 0, is it guaranteed that (at least) nb_want bytes are
1906 * available (from this read and/or a previous one). Otherwise, an error code
1907 * is returned (possibly EOF or WANT_READ).
1908 *
1909 * With stream transport (TLS) on success ssl->in_left == nb_want, but
1910 * with datagram transport (DTLS) on success ssl->in_left >= nb_want,
1911 * since we always read a whole datagram at once.
1912 *
1913 * For DTLS, it is up to the caller to set ssl->next_record_offset when
1914 * they're done reading a record.
1915 */
mbedtls_ssl_fetch_input(mbedtls_ssl_context * ssl,size_t nb_want)1916 int mbedtls_ssl_fetch_input(mbedtls_ssl_context *ssl, size_t nb_want)
1917 {
1918 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1919 size_t len;
1920 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
1921 size_t in_buf_len = ssl->in_buf_len;
1922 #else
1923 size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN;
1924 #endif
1925
1926 MBEDTLS_SSL_DEBUG_MSG(2, ("=> fetch input"));
1927
1928 if (ssl->f_recv == NULL && ssl->f_recv_timeout == NULL) {
1929 MBEDTLS_SSL_DEBUG_MSG(1, ("Bad usage of mbedtls_ssl_set_bio() "));
1930 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
1931 }
1932
1933 if (nb_want > in_buf_len - (size_t) (ssl->in_hdr - ssl->in_buf)) {
1934 MBEDTLS_SSL_DEBUG_MSG(1, ("requesting more data than fits"));
1935 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
1936 }
1937
1938 #if defined(MBEDTLS_SSL_PROTO_DTLS)
1939 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
1940 uint32_t timeout;
1941
1942 /*
1943 * The point is, we need to always read a full datagram at once, so we
1944 * sometimes read more then requested, and handle the additional data.
1945 * It could be the rest of the current record (while fetching the
1946 * header) and/or some other records in the same datagram.
1947 */
1948
1949 /*
1950 * Move to the next record in the already read datagram if applicable
1951 */
1952 if (ssl->next_record_offset != 0) {
1953 if (ssl->in_left < ssl->next_record_offset) {
1954 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
1955 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1956 }
1957
1958 ssl->in_left -= ssl->next_record_offset;
1959
1960 if (ssl->in_left != 0) {
1961 MBEDTLS_SSL_DEBUG_MSG(2, ("next record in same datagram, offset: %"
1962 MBEDTLS_PRINTF_SIZET,
1963 ssl->next_record_offset));
1964 memmove(ssl->in_hdr,
1965 ssl->in_hdr + ssl->next_record_offset,
1966 ssl->in_left);
1967 }
1968
1969 ssl->next_record_offset = 0;
1970 }
1971
1972 MBEDTLS_SSL_DEBUG_MSG(2, ("in_left: %" MBEDTLS_PRINTF_SIZET
1973 ", nb_want: %" MBEDTLS_PRINTF_SIZET,
1974 ssl->in_left, nb_want));
1975
1976 /*
1977 * Done if we already have enough data.
1978 */
1979 if (nb_want <= ssl->in_left) {
1980 MBEDTLS_SSL_DEBUG_MSG(2, ("<= fetch input"));
1981 return 0;
1982 }
1983
1984 /*
1985 * A record can't be split across datagrams. If we need to read but
1986 * are not at the beginning of a new record, the caller did something
1987 * wrong.
1988 */
1989 if (ssl->in_left != 0) {
1990 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
1991 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
1992 }
1993
1994 /*
1995 * Don't even try to read if time's out already.
1996 * This avoids by-passing the timer when repeatedly receiving messages
1997 * that will end up being dropped.
1998 */
1999 if (mbedtls_ssl_check_timer(ssl) != 0) {
2000 MBEDTLS_SSL_DEBUG_MSG(2, ("timer has expired"));
2001 ret = MBEDTLS_ERR_SSL_TIMEOUT;
2002 } else {
2003 len = in_buf_len - (ssl->in_hdr - ssl->in_buf);
2004
2005 if (mbedtls_ssl_is_handshake_over(ssl) == 0) {
2006 timeout = ssl->handshake->retransmit_timeout;
2007 } else {
2008 timeout = ssl->conf->read_timeout;
2009 }
2010
2011 MBEDTLS_SSL_DEBUG_MSG(3, ("f_recv_timeout: %lu ms", (unsigned long) timeout));
2012
2013 if (ssl->f_recv_timeout != NULL) {
2014 ret = ssl->f_recv_timeout(ssl->p_bio, ssl->in_hdr, len,
2015 timeout);
2016 } else {
2017 ret = ssl->f_recv(ssl->p_bio, ssl->in_hdr, len);
2018 }
2019
2020 MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_recv(_timeout)", ret);
2021
2022 if (ret == 0) {
2023 return MBEDTLS_ERR_SSL_CONN_EOF;
2024 }
2025 }
2026
2027 if (ret == MBEDTLS_ERR_SSL_TIMEOUT) {
2028 MBEDTLS_SSL_DEBUG_MSG(2, ("timeout"));
2029 mbedtls_ssl_set_timer(ssl, 0);
2030
2031 if (ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER) {
2032 if (ssl_double_retransmit_timeout(ssl) != 0) {
2033 MBEDTLS_SSL_DEBUG_MSG(1, ("handshake timeout"));
2034 return MBEDTLS_ERR_SSL_TIMEOUT;
2035 }
2036
2037 if ((ret = mbedtls_ssl_resend(ssl)) != 0) {
2038 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend", ret);
2039 return ret;
2040 }
2041
2042 return MBEDTLS_ERR_SSL_WANT_READ;
2043 }
2044 #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
2045 else if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
2046 ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING) {
2047 if ((ret = mbedtls_ssl_resend_hello_request(ssl)) != 0) {
2048 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend_hello_request",
2049 ret);
2050 return ret;
2051 }
2052
2053 return MBEDTLS_ERR_SSL_WANT_READ;
2054 }
2055 #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
2056 }
2057
2058 if (ret < 0) {
2059 return ret;
2060 }
2061
2062 ssl->in_left = ret;
2063 } else
2064 #endif
2065 {
2066 MBEDTLS_SSL_DEBUG_MSG(2, ("in_left: %" MBEDTLS_PRINTF_SIZET
2067 ", nb_want: %" MBEDTLS_PRINTF_SIZET,
2068 ssl->in_left, nb_want));
2069
2070 while (ssl->in_left < nb_want) {
2071 len = nb_want - ssl->in_left;
2072
2073 if (mbedtls_ssl_check_timer(ssl) != 0) {
2074 ret = MBEDTLS_ERR_SSL_TIMEOUT;
2075 } else {
2076 if (ssl->f_recv_timeout != NULL) {
2077 ret = ssl->f_recv_timeout(ssl->p_bio,
2078 ssl->in_hdr + ssl->in_left, len,
2079 ssl->conf->read_timeout);
2080 } else {
2081 ret = ssl->f_recv(ssl->p_bio,
2082 ssl->in_hdr + ssl->in_left, len);
2083 }
2084 }
2085
2086 MBEDTLS_SSL_DEBUG_MSG(2, ("in_left: %" MBEDTLS_PRINTF_SIZET
2087 ", nb_want: %" MBEDTLS_PRINTF_SIZET,
2088 ssl->in_left, nb_want));
2089 MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_recv(_timeout)", ret);
2090
2091 if (ret == 0) {
2092 return MBEDTLS_ERR_SSL_CONN_EOF;
2093 }
2094
2095 if (ret < 0) {
2096 return ret;
2097 }
2098
2099 if ((size_t) ret > len) {
2100 MBEDTLS_SSL_DEBUG_MSG(1,
2101 ("f_recv returned %d bytes but only %" MBEDTLS_PRINTF_SIZET
2102 " were requested",
2103 ret, len));
2104 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
2105 }
2106
2107 ssl->in_left += ret;
2108 }
2109 }
2110
2111 MBEDTLS_SSL_DEBUG_MSG(2, ("<= fetch input"));
2112
2113 return 0;
2114 }
2115
2116 /*
2117 * Flush any data not yet written
2118 */
mbedtls_ssl_flush_output(mbedtls_ssl_context * ssl)2119 int mbedtls_ssl_flush_output(mbedtls_ssl_context *ssl)
2120 {
2121 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2122 unsigned char *buf;
2123
2124 MBEDTLS_SSL_DEBUG_MSG(2, ("=> flush output"));
2125
2126 if (ssl->f_send == NULL) {
2127 MBEDTLS_SSL_DEBUG_MSG(1, ("Bad usage of mbedtls_ssl_set_bio() "));
2128 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
2129 }
2130
2131 /* Avoid incrementing counter if data is flushed */
2132 if (ssl->out_left == 0) {
2133 MBEDTLS_SSL_DEBUG_MSG(2, ("<= flush output"));
2134 return 0;
2135 }
2136
2137 while (ssl->out_left > 0) {
2138 MBEDTLS_SSL_DEBUG_MSG(2, ("message length: %" MBEDTLS_PRINTF_SIZET
2139 ", out_left: %" MBEDTLS_PRINTF_SIZET,
2140 mbedtls_ssl_out_hdr_len(ssl) + ssl->out_msglen, ssl->out_left));
2141
2142 buf = ssl->out_hdr - ssl->out_left;
2143 ret = ssl->f_send(ssl->p_bio, buf, ssl->out_left);
2144
2145 MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_send", ret);
2146
2147 if (ret <= 0) {
2148 return ret;
2149 }
2150
2151 if ((size_t) ret > ssl->out_left) {
2152 MBEDTLS_SSL_DEBUG_MSG(1,
2153 ("f_send returned %d bytes but only %" MBEDTLS_PRINTF_SIZET
2154 " bytes were sent",
2155 ret, ssl->out_left));
2156 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
2157 }
2158
2159 ssl->out_left -= ret;
2160 }
2161
2162 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2163 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
2164 ssl->out_hdr = ssl->out_buf;
2165 } else
2166 #endif
2167 {
2168 ssl->out_hdr = ssl->out_buf + 8;
2169 }
2170 mbedtls_ssl_update_out_pointers(ssl, ssl->transform_out);
2171
2172 MBEDTLS_SSL_DEBUG_MSG(2, ("<= flush output"));
2173
2174 return 0;
2175 }
2176
2177 /*
2178 * Functions to handle the DTLS retransmission state machine
2179 */
2180 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2181 /*
2182 * Append current handshake message to current outgoing flight
2183 */
2184 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_flight_append(mbedtls_ssl_context * ssl)2185 static int ssl_flight_append(mbedtls_ssl_context *ssl)
2186 {
2187 mbedtls_ssl_flight_item *msg;
2188 MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_flight_append"));
2189 MBEDTLS_SSL_DEBUG_BUF(4, "message appended to flight",
2190 ssl->out_msg, ssl->out_msglen);
2191
2192 /* Allocate space for current message */
2193 if ((msg = mbedtls_calloc(1, sizeof(mbedtls_ssl_flight_item))) == NULL) {
2194 MBEDTLS_SSL_DEBUG_MSG(1, ("alloc %" MBEDTLS_PRINTF_SIZET " bytes failed",
2195 sizeof(mbedtls_ssl_flight_item)));
2196 return MBEDTLS_ERR_SSL_ALLOC_FAILED;
2197 }
2198
2199 if ((msg->p = mbedtls_calloc(1, ssl->out_msglen)) == NULL) {
2200 MBEDTLS_SSL_DEBUG_MSG(1, ("alloc %" MBEDTLS_PRINTF_SIZET " bytes failed",
2201 ssl->out_msglen));
2202 mbedtls_free(msg);
2203 return MBEDTLS_ERR_SSL_ALLOC_FAILED;
2204 }
2205
2206 /* Copy current handshake message with headers */
2207 memcpy(msg->p, ssl->out_msg, ssl->out_msglen);
2208 msg->len = ssl->out_msglen;
2209 msg->type = ssl->out_msgtype;
2210 msg->next = NULL;
2211
2212 /* Append to the current flight */
2213 if (ssl->handshake->flight == NULL) {
2214 ssl->handshake->flight = msg;
2215 } else {
2216 mbedtls_ssl_flight_item *cur = ssl->handshake->flight;
2217 while (cur->next != NULL) {
2218 cur = cur->next;
2219 }
2220 cur->next = msg;
2221 }
2222
2223 MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_flight_append"));
2224 return 0;
2225 }
2226
2227 /*
2228 * Free the current flight of handshake messages
2229 */
mbedtls_ssl_flight_free(mbedtls_ssl_flight_item * flight)2230 void mbedtls_ssl_flight_free(mbedtls_ssl_flight_item *flight)
2231 {
2232 mbedtls_ssl_flight_item *cur = flight;
2233 mbedtls_ssl_flight_item *next;
2234
2235 while (cur != NULL) {
2236 next = cur->next;
2237
2238 mbedtls_free(cur->p);
2239 mbedtls_free(cur);
2240
2241 cur = next;
2242 }
2243 }
2244
2245 /*
2246 * Swap transform_out and out_ctr with the alternative ones
2247 */
2248 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_swap_epochs(mbedtls_ssl_context * ssl)2249 static int ssl_swap_epochs(mbedtls_ssl_context *ssl)
2250 {
2251 mbedtls_ssl_transform *tmp_transform;
2252 unsigned char tmp_out_ctr[MBEDTLS_SSL_SEQUENCE_NUMBER_LEN];
2253
2254 if (ssl->transform_out == ssl->handshake->alt_transform_out) {
2255 MBEDTLS_SSL_DEBUG_MSG(3, ("skip swap epochs"));
2256 return 0;
2257 }
2258
2259 MBEDTLS_SSL_DEBUG_MSG(3, ("swap epochs"));
2260
2261 /* Swap transforms */
2262 tmp_transform = ssl->transform_out;
2263 ssl->transform_out = ssl->handshake->alt_transform_out;
2264 ssl->handshake->alt_transform_out = tmp_transform;
2265
2266 /* Swap epoch + sequence_number */
2267 memcpy(tmp_out_ctr, ssl->cur_out_ctr, sizeof(tmp_out_ctr));
2268 memcpy(ssl->cur_out_ctr, ssl->handshake->alt_out_ctr,
2269 sizeof(ssl->cur_out_ctr));
2270 memcpy(ssl->handshake->alt_out_ctr, tmp_out_ctr,
2271 sizeof(ssl->handshake->alt_out_ctr));
2272
2273 /* Adjust to the newly activated transform */
2274 mbedtls_ssl_update_out_pointers(ssl, ssl->transform_out);
2275
2276 return 0;
2277 }
2278
2279 /*
2280 * Retransmit the current flight of messages.
2281 */
mbedtls_ssl_resend(mbedtls_ssl_context * ssl)2282 int mbedtls_ssl_resend(mbedtls_ssl_context *ssl)
2283 {
2284 int ret = 0;
2285
2286 MBEDTLS_SSL_DEBUG_MSG(2, ("=> mbedtls_ssl_resend"));
2287
2288 ret = mbedtls_ssl_flight_transmit(ssl);
2289
2290 MBEDTLS_SSL_DEBUG_MSG(2, ("<= mbedtls_ssl_resend"));
2291
2292 return ret;
2293 }
2294
2295 /*
2296 * Transmit or retransmit the current flight of messages.
2297 *
2298 * Need to remember the current message in case flush_output returns
2299 * WANT_WRITE, causing us to exit this function and come back later.
2300 * This function must be called until state is no longer SENDING.
2301 */
mbedtls_ssl_flight_transmit(mbedtls_ssl_context * ssl)2302 int mbedtls_ssl_flight_transmit(mbedtls_ssl_context *ssl)
2303 {
2304 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2305 MBEDTLS_SSL_DEBUG_MSG(2, ("=> mbedtls_ssl_flight_transmit"));
2306
2307 if (ssl->handshake->retransmit_state != MBEDTLS_SSL_RETRANS_SENDING) {
2308 MBEDTLS_SSL_DEBUG_MSG(2, ("initialise flight transmission"));
2309
2310 ssl->handshake->cur_msg = ssl->handshake->flight;
2311 ssl->handshake->cur_msg_p = ssl->handshake->flight->p + 12;
2312 ret = ssl_swap_epochs(ssl);
2313 if (ret != 0) {
2314 return ret;
2315 }
2316
2317 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_SENDING;
2318 }
2319
2320 while (ssl->handshake->cur_msg != NULL) {
2321 size_t max_frag_len;
2322 const mbedtls_ssl_flight_item * const cur = ssl->handshake->cur_msg;
2323
2324 int const is_finished =
2325 (cur->type == MBEDTLS_SSL_MSG_HANDSHAKE &&
2326 cur->p[0] == MBEDTLS_SSL_HS_FINISHED);
2327
2328 int const force_flush = ssl->disable_datagram_packing == 1 ?
2329 SSL_FORCE_FLUSH : SSL_DONT_FORCE_FLUSH;
2330
2331 /* Swap epochs before sending Finished: we can't do it after
2332 * sending ChangeCipherSpec, in case write returns WANT_READ.
2333 * Must be done before copying, may change out_msg pointer */
2334 if (is_finished && ssl->handshake->cur_msg_p == (cur->p + 12)) {
2335 MBEDTLS_SSL_DEBUG_MSG(2, ("swap epochs to send finished message"));
2336 ret = ssl_swap_epochs(ssl);
2337 if (ret != 0) {
2338 return ret;
2339 }
2340 }
2341
2342 ret = ssl_get_remaining_payload_in_datagram(ssl);
2343 if (ret < 0) {
2344 return ret;
2345 }
2346 max_frag_len = (size_t) ret;
2347
2348 /* CCS is copied as is, while HS messages may need fragmentation */
2349 if (cur->type == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) {
2350 if (max_frag_len == 0) {
2351 if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) {
2352 return ret;
2353 }
2354
2355 continue;
2356 }
2357
2358 memcpy(ssl->out_msg, cur->p, cur->len);
2359 ssl->out_msglen = cur->len;
2360 ssl->out_msgtype = cur->type;
2361
2362 /* Update position inside current message */
2363 ssl->handshake->cur_msg_p += cur->len;
2364 } else {
2365 const unsigned char * const p = ssl->handshake->cur_msg_p;
2366 const size_t hs_len = cur->len - 12;
2367 const size_t frag_off = p - (cur->p + 12);
2368 const size_t rem_len = hs_len - frag_off;
2369 size_t cur_hs_frag_len, max_hs_frag_len;
2370
2371 if ((max_frag_len < 12) || (max_frag_len == 12 && hs_len != 0)) {
2372 if (is_finished) {
2373 ret = ssl_swap_epochs(ssl);
2374 if (ret != 0) {
2375 return ret;
2376 }
2377 }
2378
2379 if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) {
2380 return ret;
2381 }
2382
2383 continue;
2384 }
2385 max_hs_frag_len = max_frag_len - 12;
2386
2387 cur_hs_frag_len = rem_len > max_hs_frag_len ?
2388 max_hs_frag_len : rem_len;
2389
2390 if (frag_off == 0 && cur_hs_frag_len != hs_len) {
2391 MBEDTLS_SSL_DEBUG_MSG(2, ("fragmenting handshake message (%u > %u)",
2392 (unsigned) cur_hs_frag_len,
2393 (unsigned) max_hs_frag_len));
2394 }
2395
2396 /* Messages are stored with handshake headers as if not fragmented,
2397 * copy beginning of headers then fill fragmentation fields.
2398 * Handshake headers: type(1) len(3) seq(2) f_off(3) f_len(3) */
2399 memcpy(ssl->out_msg, cur->p, 6);
2400
2401 ssl->out_msg[6] = MBEDTLS_BYTE_2(frag_off);
2402 ssl->out_msg[7] = MBEDTLS_BYTE_1(frag_off);
2403 ssl->out_msg[8] = MBEDTLS_BYTE_0(frag_off);
2404
2405 ssl->out_msg[9] = MBEDTLS_BYTE_2(cur_hs_frag_len);
2406 ssl->out_msg[10] = MBEDTLS_BYTE_1(cur_hs_frag_len);
2407 ssl->out_msg[11] = MBEDTLS_BYTE_0(cur_hs_frag_len);
2408
2409 MBEDTLS_SSL_DEBUG_BUF(3, "handshake header", ssl->out_msg, 12);
2410
2411 /* Copy the handshake message content and set records fields */
2412 memcpy(ssl->out_msg + 12, p, cur_hs_frag_len);
2413 ssl->out_msglen = cur_hs_frag_len + 12;
2414 ssl->out_msgtype = cur->type;
2415
2416 /* Update position inside current message */
2417 ssl->handshake->cur_msg_p += cur_hs_frag_len;
2418 }
2419
2420 /* If done with the current message move to the next one if any */
2421 if (ssl->handshake->cur_msg_p >= cur->p + cur->len) {
2422 if (cur->next != NULL) {
2423 ssl->handshake->cur_msg = cur->next;
2424 ssl->handshake->cur_msg_p = cur->next->p + 12;
2425 } else {
2426 ssl->handshake->cur_msg = NULL;
2427 ssl->handshake->cur_msg_p = NULL;
2428 }
2429 }
2430
2431 /* Actually send the message out */
2432 if ((ret = mbedtls_ssl_write_record(ssl, force_flush)) != 0) {
2433 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_record", ret);
2434 return ret;
2435 }
2436 }
2437
2438 if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) {
2439 return ret;
2440 }
2441
2442 /* Update state and set timer */
2443 if (mbedtls_ssl_is_handshake_over(ssl) == 1) {
2444 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
2445 } else {
2446 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
2447 mbedtls_ssl_set_timer(ssl, ssl->handshake->retransmit_timeout);
2448 }
2449
2450 MBEDTLS_SSL_DEBUG_MSG(2, ("<= mbedtls_ssl_flight_transmit"));
2451
2452 return 0;
2453 }
2454
2455 /*
2456 * To be called when the last message of an incoming flight is received.
2457 */
mbedtls_ssl_recv_flight_completed(mbedtls_ssl_context * ssl)2458 void mbedtls_ssl_recv_flight_completed(mbedtls_ssl_context *ssl)
2459 {
2460 /* We won't need to resend that one any more */
2461 mbedtls_ssl_flight_free(ssl->handshake->flight);
2462 ssl->handshake->flight = NULL;
2463 ssl->handshake->cur_msg = NULL;
2464
2465 /* The next incoming flight will start with this msg_seq */
2466 ssl->handshake->in_flight_start_seq = ssl->handshake->in_msg_seq;
2467
2468 /* We don't want to remember CCS's across flight boundaries. */
2469 ssl->handshake->buffering.seen_ccs = 0;
2470
2471 /* Clear future message buffering structure. */
2472 mbedtls_ssl_buffering_free(ssl);
2473
2474 /* Cancel timer */
2475 mbedtls_ssl_set_timer(ssl, 0);
2476
2477 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
2478 ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED) {
2479 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
2480 } else {
2481 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_PREPARING;
2482 }
2483 }
2484
2485 /*
2486 * To be called when the last message of an outgoing flight is send.
2487 */
mbedtls_ssl_send_flight_completed(mbedtls_ssl_context * ssl)2488 void mbedtls_ssl_send_flight_completed(mbedtls_ssl_context *ssl)
2489 {
2490 ssl_reset_retransmit_timeout(ssl);
2491 mbedtls_ssl_set_timer(ssl, ssl->handshake->retransmit_timeout);
2492
2493 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
2494 ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED) {
2495 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
2496 } else {
2497 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
2498 }
2499 }
2500 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2501
2502 /*
2503 * Handshake layer functions
2504 */
mbedtls_ssl_start_handshake_msg(mbedtls_ssl_context * ssl,unsigned hs_type,unsigned char ** buf,size_t * buf_len)2505 int mbedtls_ssl_start_handshake_msg(mbedtls_ssl_context *ssl, unsigned hs_type,
2506 unsigned char **buf, size_t *buf_len)
2507 {
2508 /*
2509 * Reserve 4 bytes for handshake header. ( Section 4,RFC 8446 )
2510 * ...
2511 * HandshakeType msg_type;
2512 * uint24 length;
2513 * ...
2514 */
2515 *buf = ssl->out_msg + 4;
2516 *buf_len = MBEDTLS_SSL_OUT_CONTENT_LEN - 4;
2517
2518 ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
2519 ssl->out_msg[0] = hs_type;
2520
2521 return 0;
2522 }
2523
2524 /*
2525 * Write (DTLS: or queue) current handshake (including CCS) message.
2526 *
2527 * - fill in handshake headers
2528 * - update handshake checksum
2529 * - DTLS: save message for resending
2530 * - then pass to the record layer
2531 *
2532 * DTLS: except for HelloRequest, messages are only queued, and will only be
2533 * actually sent when calling flight_transmit() or resend().
2534 *
2535 * Inputs:
2536 * - ssl->out_msglen: 4 + actual handshake message len
2537 * (4 is the size of handshake headers for TLS)
2538 * - ssl->out_msg[0]: the handshake type (ClientHello, ServerHello, etc)
2539 * - ssl->out_msg + 4: the handshake message body
2540 *
2541 * Outputs, ie state before passing to flight_append() or write_record():
2542 * - ssl->out_msglen: the length of the record contents
2543 * (including handshake headers but excluding record headers)
2544 * - ssl->out_msg: the record contents (handshake headers + content)
2545 */
mbedtls_ssl_write_handshake_msg_ext(mbedtls_ssl_context * ssl,int update_checksum,int force_flush)2546 int mbedtls_ssl_write_handshake_msg_ext(mbedtls_ssl_context *ssl,
2547 int update_checksum,
2548 int force_flush)
2549 {
2550 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2551 const size_t hs_len = ssl->out_msglen - 4;
2552 const unsigned char hs_type = ssl->out_msg[0];
2553
2554 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write handshake message"));
2555
2556 /*
2557 * Sanity checks
2558 */
2559 if (ssl->out_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE &&
2560 ssl->out_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) {
2561 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
2562 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
2563 }
2564
2565 /* Whenever we send anything different from a
2566 * HelloRequest we should be in a handshake - double check. */
2567 if (!(ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
2568 hs_type == MBEDTLS_SSL_HS_HELLO_REQUEST) &&
2569 ssl->handshake == NULL) {
2570 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
2571 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
2572 }
2573
2574 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2575 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
2576 ssl->handshake != NULL &&
2577 ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING) {
2578 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
2579 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
2580 }
2581 #endif
2582
2583 /* Double-check that we did not exceed the bounds
2584 * of the outgoing record buffer.
2585 * This should never fail as the various message
2586 * writing functions must obey the bounds of the
2587 * outgoing record buffer, but better be safe.
2588 *
2589 * Note: We deliberately do not check for the MTU or MFL here.
2590 */
2591 if (ssl->out_msglen > MBEDTLS_SSL_OUT_CONTENT_LEN) {
2592 MBEDTLS_SSL_DEBUG_MSG(1, ("Record too large: "
2593 "size %" MBEDTLS_PRINTF_SIZET
2594 ", maximum %" MBEDTLS_PRINTF_SIZET,
2595 ssl->out_msglen,
2596 (size_t) MBEDTLS_SSL_OUT_CONTENT_LEN));
2597 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
2598 }
2599
2600 /*
2601 * Fill handshake headers
2602 */
2603 if (ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE) {
2604 ssl->out_msg[1] = MBEDTLS_BYTE_2(hs_len);
2605 ssl->out_msg[2] = MBEDTLS_BYTE_1(hs_len);
2606 ssl->out_msg[3] = MBEDTLS_BYTE_0(hs_len);
2607
2608 /*
2609 * DTLS has additional fields in the Handshake layer,
2610 * between the length field and the actual payload:
2611 * uint16 message_seq;
2612 * uint24 fragment_offset;
2613 * uint24 fragment_length;
2614 */
2615 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2616 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
2617 /* Make room for the additional DTLS fields */
2618 if (MBEDTLS_SSL_OUT_CONTENT_LEN - ssl->out_msglen < 8) {
2619 MBEDTLS_SSL_DEBUG_MSG(1, ("DTLS handshake message too large: "
2620 "size %" MBEDTLS_PRINTF_SIZET ", maximum %"
2621 MBEDTLS_PRINTF_SIZET,
2622 hs_len,
2623 (size_t) (MBEDTLS_SSL_OUT_CONTENT_LEN - 12)));
2624 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
2625 }
2626
2627 memmove(ssl->out_msg + 12, ssl->out_msg + 4, hs_len);
2628 ssl->out_msglen += 8;
2629
2630 /* Write message_seq and update it, except for HelloRequest */
2631 if (hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST) {
2632 MBEDTLS_PUT_UINT16_BE(ssl->handshake->out_msg_seq, ssl->out_msg, 4);
2633 ++(ssl->handshake->out_msg_seq);
2634 } else {
2635 ssl->out_msg[4] = 0;
2636 ssl->out_msg[5] = 0;
2637 }
2638
2639 /* Handshake hashes are computed without fragmentation,
2640 * so set frag_offset = 0 and frag_len = hs_len for now */
2641 memset(ssl->out_msg + 6, 0x00, 3);
2642 memcpy(ssl->out_msg + 9, ssl->out_msg + 1, 3);
2643 }
2644 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2645
2646 /* Update running hashes of handshake messages seen */
2647 if (hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST && update_checksum != 0) {
2648 ret = ssl->handshake->update_checksum(ssl, ssl->out_msg,
2649 ssl->out_msglen);
2650 if (ret != 0) {
2651 MBEDTLS_SSL_DEBUG_RET(1, "update_checksum", ret);
2652 return ret;
2653 }
2654 }
2655 }
2656
2657 /* Either send now, or just save to be sent (and resent) later */
2658 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2659 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
2660 !(ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
2661 hs_type == MBEDTLS_SSL_HS_HELLO_REQUEST)) {
2662 if ((ret = ssl_flight_append(ssl)) != 0) {
2663 MBEDTLS_SSL_DEBUG_RET(1, "ssl_flight_append", ret);
2664 return ret;
2665 }
2666 } else
2667 #endif
2668 {
2669 if ((ret = mbedtls_ssl_write_record(ssl, force_flush)) != 0) {
2670 MBEDTLS_SSL_DEBUG_RET(1, "ssl_write_record", ret);
2671 return ret;
2672 }
2673 }
2674
2675 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write handshake message"));
2676
2677 return 0;
2678 }
2679
mbedtls_ssl_finish_handshake_msg(mbedtls_ssl_context * ssl,size_t buf_len,size_t msg_len)2680 int mbedtls_ssl_finish_handshake_msg(mbedtls_ssl_context *ssl,
2681 size_t buf_len, size_t msg_len)
2682 {
2683 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2684 size_t msg_with_header_len;
2685 ((void) buf_len);
2686
2687 /* Add reserved 4 bytes for handshake header */
2688 msg_with_header_len = msg_len + 4;
2689 ssl->out_msglen = msg_with_header_len;
2690 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_write_handshake_msg_ext(ssl, 0, 0));
2691
2692 cleanup:
2693 return ret;
2694 }
2695
2696 /*
2697 * Record layer functions
2698 */
2699
2700 /*
2701 * Write current record.
2702 *
2703 * Uses:
2704 * - ssl->out_msgtype: type of the message (AppData, Handshake, Alert, CCS)
2705 * - ssl->out_msglen: length of the record content (excl headers)
2706 * - ssl->out_msg: record content
2707 */
mbedtls_ssl_write_record(mbedtls_ssl_context * ssl,int force_flush)2708 int mbedtls_ssl_write_record(mbedtls_ssl_context *ssl, int force_flush)
2709 {
2710 int ret, done = 0;
2711 size_t len = ssl->out_msglen;
2712 int flush = force_flush;
2713
2714 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write record"));
2715
2716 if (!done) {
2717 unsigned i;
2718 size_t protected_record_size;
2719 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
2720 size_t out_buf_len = ssl->out_buf_len;
2721 #else
2722 size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN;
2723 #endif
2724 /* Skip writing the record content type to after the encryption,
2725 * as it may change when using the CID extension. */
2726 mbedtls_ssl_protocol_version tls_ver = ssl->tls_version;
2727 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
2728 /* TLS 1.3 still uses the TLS 1.2 version identifier
2729 * for backwards compatibility. */
2730 if (tls_ver == MBEDTLS_SSL_VERSION_TLS1_3) {
2731 tls_ver = MBEDTLS_SSL_VERSION_TLS1_2;
2732 }
2733 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
2734 mbedtls_ssl_write_version(ssl->out_hdr + 1, ssl->conf->transport,
2735 tls_ver);
2736
2737 memcpy(ssl->out_ctr, ssl->cur_out_ctr, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN);
2738 MBEDTLS_PUT_UINT16_BE(len, ssl->out_len, 0);
2739
2740 if (ssl->transform_out != NULL) {
2741 mbedtls_record rec;
2742
2743 rec.buf = ssl->out_iv;
2744 rec.buf_len = out_buf_len - (ssl->out_iv - ssl->out_buf);
2745 rec.data_len = ssl->out_msglen;
2746 rec.data_offset = ssl->out_msg - rec.buf;
2747
2748 memcpy(&rec.ctr[0], ssl->out_ctr, sizeof(rec.ctr));
2749 mbedtls_ssl_write_version(rec.ver, ssl->conf->transport, tls_ver);
2750 rec.type = ssl->out_msgtype;
2751
2752 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
2753 /* The CID is set by mbedtls_ssl_encrypt_buf(). */
2754 rec.cid_len = 0;
2755 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
2756
2757 if ((ret = mbedtls_ssl_encrypt_buf(ssl, ssl->transform_out, &rec,
2758 ssl->conf->f_rng, ssl->conf->p_rng)) != 0) {
2759 MBEDTLS_SSL_DEBUG_RET(1, "ssl_encrypt_buf", ret);
2760 return ret;
2761 }
2762
2763 if (rec.data_offset != 0) {
2764 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
2765 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
2766 }
2767
2768 /* Update the record content type and CID. */
2769 ssl->out_msgtype = rec.type;
2770 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
2771 memcpy(ssl->out_cid, rec.cid, rec.cid_len);
2772 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
2773 ssl->out_msglen = len = rec.data_len;
2774 MBEDTLS_PUT_UINT16_BE(rec.data_len, ssl->out_len, 0);
2775 }
2776
2777 protected_record_size = len + mbedtls_ssl_out_hdr_len(ssl);
2778
2779 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2780 /* In case of DTLS, double-check that we don't exceed
2781 * the remaining space in the datagram. */
2782 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
2783 ret = ssl_get_remaining_space_in_datagram(ssl);
2784 if (ret < 0) {
2785 return ret;
2786 }
2787
2788 if (protected_record_size > (size_t) ret) {
2789 /* Should never happen */
2790 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
2791 }
2792 }
2793 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2794
2795 /* Now write the potentially updated record content type. */
2796 ssl->out_hdr[0] = (unsigned char) ssl->out_msgtype;
2797
2798 MBEDTLS_SSL_DEBUG_MSG(3, ("output record: msgtype = %u, "
2799 "version = [%u:%u], msglen = %" MBEDTLS_PRINTF_SIZET,
2800 ssl->out_hdr[0], ssl->out_hdr[1],
2801 ssl->out_hdr[2], len));
2802
2803 MBEDTLS_SSL_DEBUG_BUF(4, "output record sent to network",
2804 ssl->out_hdr, protected_record_size);
2805
2806 ssl->out_left += protected_record_size;
2807 ssl->out_hdr += protected_record_size;
2808 mbedtls_ssl_update_out_pointers(ssl, ssl->transform_out);
2809
2810 for (i = 8; i > mbedtls_ssl_ep_len(ssl); i--) {
2811 if (++ssl->cur_out_ctr[i - 1] != 0) {
2812 break;
2813 }
2814 }
2815
2816 /* The loop goes to its end if the counter is wrapping */
2817 if (i == mbedtls_ssl_ep_len(ssl)) {
2818 MBEDTLS_SSL_DEBUG_MSG(1, ("outgoing message counter would wrap"));
2819 return MBEDTLS_ERR_SSL_COUNTER_WRAPPING;
2820 }
2821 }
2822
2823 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2824 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
2825 flush == SSL_DONT_FORCE_FLUSH) {
2826 size_t remaining;
2827 ret = ssl_get_remaining_payload_in_datagram(ssl);
2828 if (ret < 0) {
2829 MBEDTLS_SSL_DEBUG_RET(1, "ssl_get_remaining_payload_in_datagram",
2830 ret);
2831 return ret;
2832 }
2833
2834 remaining = (size_t) ret;
2835 if (remaining == 0) {
2836 flush = SSL_FORCE_FLUSH;
2837 } else {
2838 MBEDTLS_SSL_DEBUG_MSG(2,
2839 ("Still %u bytes available in current datagram",
2840 (unsigned) remaining));
2841 }
2842 }
2843 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2844
2845 if ((flush == SSL_FORCE_FLUSH) &&
2846 (ret = mbedtls_ssl_flush_output(ssl)) != 0) {
2847 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_flush_output", ret);
2848 return ret;
2849 }
2850
2851 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write record"));
2852
2853 return 0;
2854 }
2855
2856 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2857
2858 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_hs_is_proper_fragment(mbedtls_ssl_context * ssl)2859 static int ssl_hs_is_proper_fragment(mbedtls_ssl_context *ssl)
2860 {
2861 if (ssl->in_msglen < ssl->in_hslen ||
2862 memcmp(ssl->in_msg + 6, "\0\0\0", 3) != 0 ||
2863 memcmp(ssl->in_msg + 9, ssl->in_msg + 1, 3) != 0) {
2864 return 1;
2865 }
2866 return 0;
2867 }
2868
ssl_get_hs_frag_len(mbedtls_ssl_context const * ssl)2869 static uint32_t ssl_get_hs_frag_len(mbedtls_ssl_context const *ssl)
2870 {
2871 return (ssl->in_msg[9] << 16) |
2872 (ssl->in_msg[10] << 8) |
2873 ssl->in_msg[11];
2874 }
2875
ssl_get_hs_frag_off(mbedtls_ssl_context const * ssl)2876 static uint32_t ssl_get_hs_frag_off(mbedtls_ssl_context const *ssl)
2877 {
2878 return (ssl->in_msg[6] << 16) |
2879 (ssl->in_msg[7] << 8) |
2880 ssl->in_msg[8];
2881 }
2882
2883 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_check_hs_header(mbedtls_ssl_context const * ssl)2884 static int ssl_check_hs_header(mbedtls_ssl_context const *ssl)
2885 {
2886 uint32_t msg_len, frag_off, frag_len;
2887
2888 msg_len = ssl_get_hs_total_len(ssl);
2889 frag_off = ssl_get_hs_frag_off(ssl);
2890 frag_len = ssl_get_hs_frag_len(ssl);
2891
2892 if (frag_off > msg_len) {
2893 return -1;
2894 }
2895
2896 if (frag_len > msg_len - frag_off) {
2897 return -1;
2898 }
2899
2900 if (frag_len + 12 > ssl->in_msglen) {
2901 return -1;
2902 }
2903
2904 return 0;
2905 }
2906
2907 /*
2908 * Mark bits in bitmask (used for DTLS HS reassembly)
2909 */
ssl_bitmask_set(unsigned char * mask,size_t offset,size_t len)2910 static void ssl_bitmask_set(unsigned char *mask, size_t offset, size_t len)
2911 {
2912 unsigned int start_bits, end_bits;
2913
2914 start_bits = 8 - (offset % 8);
2915 if (start_bits != 8) {
2916 size_t first_byte_idx = offset / 8;
2917
2918 /* Special case */
2919 if (len <= start_bits) {
2920 for (; len != 0; len--) {
2921 mask[first_byte_idx] |= 1 << (start_bits - len);
2922 }
2923
2924 /* Avoid potential issues with offset or len becoming invalid */
2925 return;
2926 }
2927
2928 offset += start_bits; /* Now offset % 8 == 0 */
2929 len -= start_bits;
2930
2931 for (; start_bits != 0; start_bits--) {
2932 mask[first_byte_idx] |= 1 << (start_bits - 1);
2933 }
2934 }
2935
2936 end_bits = len % 8;
2937 if (end_bits != 0) {
2938 size_t last_byte_idx = (offset + len) / 8;
2939
2940 len -= end_bits; /* Now len % 8 == 0 */
2941
2942 for (; end_bits != 0; end_bits--) {
2943 mask[last_byte_idx] |= 1 << (8 - end_bits);
2944 }
2945 }
2946
2947 memset(mask + offset / 8, 0xFF, len / 8);
2948 }
2949
2950 /*
2951 * Check that bitmask is full
2952 */
2953 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_bitmask_check(unsigned char * mask,size_t len)2954 static int ssl_bitmask_check(unsigned char *mask, size_t len)
2955 {
2956 size_t i;
2957
2958 for (i = 0; i < len / 8; i++) {
2959 if (mask[i] != 0xFF) {
2960 return -1;
2961 }
2962 }
2963
2964 for (i = 0; i < len % 8; i++) {
2965 if ((mask[len / 8] & (1 << (7 - i))) == 0) {
2966 return -1;
2967 }
2968 }
2969
2970 return 0;
2971 }
2972
2973 /* msg_len does not include the handshake header */
ssl_get_reassembly_buffer_size(size_t msg_len,unsigned add_bitmap)2974 static size_t ssl_get_reassembly_buffer_size(size_t msg_len,
2975 unsigned add_bitmap)
2976 {
2977 size_t alloc_len;
2978
2979 alloc_len = 12; /* Handshake header */
2980 alloc_len += msg_len; /* Content buffer */
2981
2982 if (add_bitmap) {
2983 alloc_len += msg_len / 8 + (msg_len % 8 != 0); /* Bitmap */
2984
2985 }
2986 return alloc_len;
2987 }
2988
2989 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2990
ssl_get_hs_total_len(mbedtls_ssl_context const * ssl)2991 static uint32_t ssl_get_hs_total_len(mbedtls_ssl_context const *ssl)
2992 {
2993 return (ssl->in_msg[1] << 16) |
2994 (ssl->in_msg[2] << 8) |
2995 ssl->in_msg[3];
2996 }
2997
mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context * ssl)2998 int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl)
2999 {
3000 if (ssl->in_msglen < mbedtls_ssl_hs_hdr_len(ssl)) {
3001 MBEDTLS_SSL_DEBUG_MSG(1, ("handshake message too short: %" MBEDTLS_PRINTF_SIZET,
3002 ssl->in_msglen));
3003 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3004 }
3005
3006 ssl->in_hslen = mbedtls_ssl_hs_hdr_len(ssl) + ssl_get_hs_total_len(ssl);
3007
3008 MBEDTLS_SSL_DEBUG_MSG(3, ("handshake message: msglen ="
3009 " %" MBEDTLS_PRINTF_SIZET ", type = %u, hslen = %"
3010 MBEDTLS_PRINTF_SIZET,
3011 ssl->in_msglen, ssl->in_msg[0], ssl->in_hslen));
3012
3013 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3014 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
3015 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
3016 unsigned int recv_msg_seq = (ssl->in_msg[4] << 8) | ssl->in_msg[5];
3017
3018 if (ssl_check_hs_header(ssl) != 0) {
3019 MBEDTLS_SSL_DEBUG_MSG(1, ("invalid handshake header"));
3020 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3021 }
3022
3023 if (ssl->handshake != NULL &&
3024 ((mbedtls_ssl_is_handshake_over(ssl) == 0 &&
3025 recv_msg_seq != ssl->handshake->in_msg_seq) ||
3026 (mbedtls_ssl_is_handshake_over(ssl) == 1 &&
3027 ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO))) {
3028 if (recv_msg_seq > ssl->handshake->in_msg_seq) {
3029 MBEDTLS_SSL_DEBUG_MSG(2,
3030 (
3031 "received future handshake message of sequence number %u (next %u)",
3032 recv_msg_seq,
3033 ssl->handshake->in_msg_seq));
3034 return MBEDTLS_ERR_SSL_EARLY_MESSAGE;
3035 }
3036
3037 /* Retransmit only on last message from previous flight, to avoid
3038 * too many retransmissions.
3039 * Besides, No sane server ever retransmits HelloVerifyRequest */
3040 if (recv_msg_seq == ssl->handshake->in_flight_start_seq - 1 &&
3041 ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST) {
3042 MBEDTLS_SSL_DEBUG_MSG(2, ("received message from last flight, "
3043 "message_seq = %u, start_of_flight = %u",
3044 recv_msg_seq,
3045 ssl->handshake->in_flight_start_seq));
3046
3047 if ((ret = mbedtls_ssl_resend(ssl)) != 0) {
3048 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend", ret);
3049 return ret;
3050 }
3051 } else {
3052 MBEDTLS_SSL_DEBUG_MSG(2, ("dropping out-of-sequence message: "
3053 "message_seq = %u, expected = %u",
3054 recv_msg_seq,
3055 ssl->handshake->in_msg_seq));
3056 }
3057
3058 return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
3059 }
3060 /* Wait until message completion to increment in_msg_seq */
3061
3062 /* Message reassembly is handled alongside buffering of future
3063 * messages; the commonality is that both handshake fragments and
3064 * future messages cannot be forwarded immediately to the
3065 * handshake logic layer. */
3066 if (ssl_hs_is_proper_fragment(ssl) == 1) {
3067 MBEDTLS_SSL_DEBUG_MSG(2, ("found fragmented DTLS handshake message"));
3068 return MBEDTLS_ERR_SSL_EARLY_MESSAGE;
3069 }
3070 } else
3071 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3072 /* With TLS we don't handle fragmentation (for now) */
3073 if (ssl->in_msglen < ssl->in_hslen) {
3074 MBEDTLS_SSL_DEBUG_MSG(1, ("TLS handshake fragmentation not supported"));
3075 return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
3076 }
3077
3078 return 0;
3079 }
3080
mbedtls_ssl_update_handshake_status(mbedtls_ssl_context * ssl)3081 int mbedtls_ssl_update_handshake_status(mbedtls_ssl_context *ssl)
3082 {
3083 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
3084 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
3085
3086 if (mbedtls_ssl_is_handshake_over(ssl) == 0 && hs != NULL) {
3087 ret = ssl->handshake->update_checksum(ssl, ssl->in_msg, ssl->in_hslen);
3088 if (ret != 0) {
3089 MBEDTLS_SSL_DEBUG_RET(1, "update_checksum", ret);
3090 return ret;
3091 }
3092 }
3093
3094 /* Handshake message is complete, increment counter */
3095 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3096 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
3097 ssl->handshake != NULL) {
3098 unsigned offset;
3099 mbedtls_ssl_hs_buffer *hs_buf;
3100
3101 /* Increment handshake sequence number */
3102 hs->in_msg_seq++;
3103
3104 /*
3105 * Clear up handshake buffering and reassembly structure.
3106 */
3107
3108 /* Free first entry */
3109 ssl_buffering_free_slot(ssl, 0);
3110
3111 /* Shift all other entries */
3112 for (offset = 0, hs_buf = &hs->buffering.hs[0];
3113 offset + 1 < MBEDTLS_SSL_MAX_BUFFERED_HS;
3114 offset++, hs_buf++) {
3115 *hs_buf = *(hs_buf + 1);
3116 }
3117
3118 /* Create a fresh last entry */
3119 memset(hs_buf, 0, sizeof(mbedtls_ssl_hs_buffer));
3120 }
3121 #endif
3122 return 0;
3123 }
3124
3125 /*
3126 * DTLS anti-replay: RFC 6347 4.1.2.6
3127 *
3128 * in_window is a field of bits numbered from 0 (lsb) to 63 (msb).
3129 * Bit n is set iff record number in_window_top - n has been seen.
3130 *
3131 * Usually, in_window_top is the last record number seen and the lsb of
3132 * in_window is set. The only exception is the initial state (record number 0
3133 * not seen yet).
3134 */
3135 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
mbedtls_ssl_dtls_replay_reset(mbedtls_ssl_context * ssl)3136 void mbedtls_ssl_dtls_replay_reset(mbedtls_ssl_context *ssl)
3137 {
3138 ssl->in_window_top = 0;
3139 ssl->in_window = 0;
3140 }
3141
ssl_load_six_bytes(unsigned char * buf)3142 static inline uint64_t ssl_load_six_bytes(unsigned char *buf)
3143 {
3144 return ((uint64_t) buf[0] << 40) |
3145 ((uint64_t) buf[1] << 32) |
3146 ((uint64_t) buf[2] << 24) |
3147 ((uint64_t) buf[3] << 16) |
3148 ((uint64_t) buf[4] << 8) |
3149 ((uint64_t) buf[5]);
3150 }
3151
3152 MBEDTLS_CHECK_RETURN_CRITICAL
mbedtls_ssl_dtls_record_replay_check(mbedtls_ssl_context * ssl,uint8_t * record_in_ctr)3153 static int mbedtls_ssl_dtls_record_replay_check(mbedtls_ssl_context *ssl, uint8_t *record_in_ctr)
3154 {
3155 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
3156 unsigned char *original_in_ctr;
3157
3158 // save original in_ctr
3159 original_in_ctr = ssl->in_ctr;
3160
3161 // use counter from record
3162 ssl->in_ctr = record_in_ctr;
3163
3164 ret = mbedtls_ssl_dtls_replay_check((mbedtls_ssl_context const *) ssl);
3165
3166 // restore the counter
3167 ssl->in_ctr = original_in_ctr;
3168
3169 return ret;
3170 }
3171
3172 /*
3173 * Return 0 if sequence number is acceptable, -1 otherwise
3174 */
mbedtls_ssl_dtls_replay_check(mbedtls_ssl_context const * ssl)3175 int mbedtls_ssl_dtls_replay_check(mbedtls_ssl_context const *ssl)
3176 {
3177 uint64_t rec_seqnum = ssl_load_six_bytes(ssl->in_ctr + 2);
3178 uint64_t bit;
3179
3180 if (ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED) {
3181 return 0;
3182 }
3183
3184 if (rec_seqnum > ssl->in_window_top) {
3185 return 0;
3186 }
3187
3188 bit = ssl->in_window_top - rec_seqnum;
3189
3190 if (bit >= 64) {
3191 return -1;
3192 }
3193
3194 if ((ssl->in_window & ((uint64_t) 1 << bit)) != 0) {
3195 return -1;
3196 }
3197
3198 return 0;
3199 }
3200
3201 /*
3202 * Update replay window on new validated record
3203 */
mbedtls_ssl_dtls_replay_update(mbedtls_ssl_context * ssl)3204 void mbedtls_ssl_dtls_replay_update(mbedtls_ssl_context *ssl)
3205 {
3206 uint64_t rec_seqnum = ssl_load_six_bytes(ssl->in_ctr + 2);
3207
3208 if (ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED) {
3209 return;
3210 }
3211
3212 if (rec_seqnum > ssl->in_window_top) {
3213 /* Update window_top and the contents of the window */
3214 uint64_t shift = rec_seqnum - ssl->in_window_top;
3215
3216 if (shift >= 64) {
3217 ssl->in_window = 1;
3218 } else {
3219 ssl->in_window <<= shift;
3220 ssl->in_window |= 1;
3221 }
3222
3223 ssl->in_window_top = rec_seqnum;
3224 } else {
3225 /* Mark that number as seen in the current window */
3226 uint64_t bit = ssl->in_window_top - rec_seqnum;
3227
3228 if (bit < 64) { /* Always true, but be extra sure */
3229 ssl->in_window |= (uint64_t) 1 << bit;
3230 }
3231 }
3232 }
3233 #endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
3234
3235 #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
3236 /*
3237 * Check if a datagram looks like a ClientHello with a valid cookie,
3238 * and if it doesn't, generate a HelloVerifyRequest message.
3239 * Both input and output include full DTLS headers.
3240 *
3241 * - if cookie is valid, return 0
3242 * - if ClientHello looks superficially valid but cookie is not,
3243 * fill obuf and set olen, then
3244 * return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED
3245 * - otherwise return a specific error code
3246 */
3247 MBEDTLS_CHECK_RETURN_CRITICAL
3248 MBEDTLS_STATIC_TESTABLE
mbedtls_ssl_check_dtls_clihlo_cookie(mbedtls_ssl_context * ssl,const unsigned char * cli_id,size_t cli_id_len,const unsigned char * in,size_t in_len,unsigned char * obuf,size_t buf_len,size_t * olen)3249 int mbedtls_ssl_check_dtls_clihlo_cookie(
3250 mbedtls_ssl_context *ssl,
3251 const unsigned char *cli_id, size_t cli_id_len,
3252 const unsigned char *in, size_t in_len,
3253 unsigned char *obuf, size_t buf_len, size_t *olen)
3254 {
3255 size_t sid_len, cookie_len, epoch, fragment_offset;
3256 unsigned char *p;
3257
3258 /*
3259 * Structure of ClientHello with record and handshake headers,
3260 * and expected values. We don't need to check a lot, more checks will be
3261 * done when actually parsing the ClientHello - skipping those checks
3262 * avoids code duplication and does not make cookie forging any easier.
3263 *
3264 * 0-0 ContentType type; copied, must be handshake
3265 * 1-2 ProtocolVersion version; copied
3266 * 3-4 uint16 epoch; copied, must be 0
3267 * 5-10 uint48 sequence_number; copied
3268 * 11-12 uint16 length; (ignored)
3269 *
3270 * 13-13 HandshakeType msg_type; (ignored)
3271 * 14-16 uint24 length; (ignored)
3272 * 17-18 uint16 message_seq; copied
3273 * 19-21 uint24 fragment_offset; copied, must be 0
3274 * 22-24 uint24 fragment_length; (ignored)
3275 *
3276 * 25-26 ProtocolVersion client_version; (ignored)
3277 * 27-58 Random random; (ignored)
3278 * 59-xx SessionID session_id; 1 byte len + sid_len content
3279 * 60+ opaque cookie<0..2^8-1>; 1 byte len + content
3280 * ...
3281 *
3282 * Minimum length is 61 bytes.
3283 */
3284 MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: in_len=%u",
3285 (unsigned) in_len));
3286 MBEDTLS_SSL_DEBUG_BUF(4, "cli_id", cli_id, cli_id_len);
3287 if (in_len < 61) {
3288 MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: record too short"));
3289 return MBEDTLS_ERR_SSL_DECODE_ERROR;
3290 }
3291
3292 epoch = MBEDTLS_GET_UINT16_BE(in, 3);
3293 fragment_offset = MBEDTLS_GET_UINT24_BE(in, 19);
3294
3295 if (in[0] != MBEDTLS_SSL_MSG_HANDSHAKE || epoch != 0 ||
3296 fragment_offset != 0) {
3297 MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: not a good ClientHello"));
3298 MBEDTLS_SSL_DEBUG_MSG(4, (" type=%u epoch=%u fragment_offset=%u",
3299 in[0], (unsigned) epoch,
3300 (unsigned) fragment_offset));
3301 return MBEDTLS_ERR_SSL_DECODE_ERROR;
3302 }
3303
3304 sid_len = in[59];
3305 if (59 + 1 + sid_len + 1 > in_len) {
3306 MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: sid_len=%u > %u",
3307 (unsigned) sid_len,
3308 (unsigned) in_len - 61));
3309 return MBEDTLS_ERR_SSL_DECODE_ERROR;
3310 }
3311 MBEDTLS_SSL_DEBUG_BUF(4, "sid received from network",
3312 in + 60, sid_len);
3313
3314 cookie_len = in[60 + sid_len];
3315 if (59 + 1 + sid_len + 1 + cookie_len > in_len) {
3316 MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: cookie_len=%u > %u",
3317 (unsigned) cookie_len,
3318 (unsigned) (in_len - sid_len - 61)));
3319 return MBEDTLS_ERR_SSL_DECODE_ERROR;
3320 }
3321
3322 MBEDTLS_SSL_DEBUG_BUF(4, "cookie received from network",
3323 in + sid_len + 61, cookie_len);
3324 if (ssl->conf->f_cookie_check(ssl->conf->p_cookie,
3325 in + sid_len + 61, cookie_len,
3326 cli_id, cli_id_len) == 0) {
3327 MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: valid"));
3328 return 0;
3329 }
3330
3331 /*
3332 * If we get here, we've got an invalid cookie, let's prepare HVR.
3333 *
3334 * 0-0 ContentType type; copied
3335 * 1-2 ProtocolVersion version; copied
3336 * 3-4 uint16 epoch; copied
3337 * 5-10 uint48 sequence_number; copied
3338 * 11-12 uint16 length; olen - 13
3339 *
3340 * 13-13 HandshakeType msg_type; hello_verify_request
3341 * 14-16 uint24 length; olen - 25
3342 * 17-18 uint16 message_seq; copied
3343 * 19-21 uint24 fragment_offset; copied
3344 * 22-24 uint24 fragment_length; olen - 25
3345 *
3346 * 25-26 ProtocolVersion server_version; 0xfe 0xff
3347 * 27-27 opaque cookie<0..2^8-1>; cookie_len = olen - 27, cookie
3348 *
3349 * Minimum length is 28.
3350 */
3351 if (buf_len < 28) {
3352 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
3353 }
3354
3355 /* Copy most fields and adapt others */
3356 memcpy(obuf, in, 25);
3357 obuf[13] = MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST;
3358 obuf[25] = 0xfe;
3359 obuf[26] = 0xff;
3360
3361 /* Generate and write actual cookie */
3362 p = obuf + 28;
3363 if (ssl->conf->f_cookie_write(ssl->conf->p_cookie,
3364 &p, obuf + buf_len,
3365 cli_id, cli_id_len) != 0) {
3366 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
3367 }
3368
3369 *olen = p - obuf;
3370
3371 /* Go back and fill length fields */
3372 obuf[27] = (unsigned char) (*olen - 28);
3373
3374 obuf[14] = obuf[22] = MBEDTLS_BYTE_2(*olen - 25);
3375 obuf[15] = obuf[23] = MBEDTLS_BYTE_1(*olen - 25);
3376 obuf[16] = obuf[24] = MBEDTLS_BYTE_0(*olen - 25);
3377
3378 MBEDTLS_PUT_UINT16_BE(*olen - 13, obuf, 11);
3379
3380 return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED;
3381 }
3382
3383 /*
3384 * Handle possible client reconnect with the same UDP quadruplet
3385 * (RFC 6347 Section 4.2.8).
3386 *
3387 * Called by ssl_parse_record_header() in case we receive an epoch 0 record
3388 * that looks like a ClientHello.
3389 *
3390 * - if the input looks like a ClientHello without cookies,
3391 * send back HelloVerifyRequest, then return 0
3392 * - if the input looks like a ClientHello with a valid cookie,
3393 * reset the session of the current context, and
3394 * return MBEDTLS_ERR_SSL_CLIENT_RECONNECT
3395 * - if anything goes wrong, return a specific error code
3396 *
3397 * This function is called (through ssl_check_client_reconnect()) when an
3398 * unexpected record is found in ssl_get_next_record(), which will discard the
3399 * record if we return 0, and bubble up the return value otherwise (this
3400 * includes the case of MBEDTLS_ERR_SSL_CLIENT_RECONNECT and of unexpected
3401 * errors, and is the right thing to do in both cases).
3402 */
3403 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_handle_possible_reconnect(mbedtls_ssl_context * ssl)3404 static int ssl_handle_possible_reconnect(mbedtls_ssl_context *ssl)
3405 {
3406 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
3407 size_t len;
3408
3409 if (ssl->conf->f_cookie_write == NULL ||
3410 ssl->conf->f_cookie_check == NULL) {
3411 /* If we can't use cookies to verify reachability of the peer,
3412 * drop the record. */
3413 MBEDTLS_SSL_DEBUG_MSG(1, ("no cookie callbacks, "
3414 "can't check reconnect validity"));
3415 return 0;
3416 }
3417
3418 ret = mbedtls_ssl_check_dtls_clihlo_cookie(
3419 ssl,
3420 ssl->cli_id, ssl->cli_id_len,
3421 ssl->in_buf, ssl->in_left,
3422 ssl->out_buf, MBEDTLS_SSL_OUT_CONTENT_LEN, &len);
3423
3424 MBEDTLS_SSL_DEBUG_RET(2, "mbedtls_ssl_check_dtls_clihlo_cookie", ret);
3425
3426 if (ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED) {
3427 int send_ret;
3428 MBEDTLS_SSL_DEBUG_MSG(1, ("sending HelloVerifyRequest"));
3429 MBEDTLS_SSL_DEBUG_BUF(4, "output record sent to network",
3430 ssl->out_buf, len);
3431 /* Don't check write errors as we can't do anything here.
3432 * If the error is permanent we'll catch it later,
3433 * if it's not, then hopefully it'll work next time. */
3434 send_ret = ssl->f_send(ssl->p_bio, ssl->out_buf, len);
3435 MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_send", send_ret);
3436 (void) send_ret;
3437
3438 return 0;
3439 }
3440
3441 if (ret == 0) {
3442 MBEDTLS_SSL_DEBUG_MSG(1, ("cookie is valid, resetting context"));
3443 if ((ret = mbedtls_ssl_session_reset_int(ssl, 1)) != 0) {
3444 MBEDTLS_SSL_DEBUG_RET(1, "reset", ret);
3445 return ret;
3446 }
3447
3448 return MBEDTLS_ERR_SSL_CLIENT_RECONNECT;
3449 }
3450
3451 return ret;
3452 }
3453 #endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
3454
3455 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_check_record_type(uint8_t record_type)3456 static int ssl_check_record_type(uint8_t record_type)
3457 {
3458 if (record_type != MBEDTLS_SSL_MSG_HANDSHAKE &&
3459 record_type != MBEDTLS_SSL_MSG_ALERT &&
3460 record_type != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC &&
3461 record_type != MBEDTLS_SSL_MSG_APPLICATION_DATA) {
3462 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3463 }
3464
3465 return 0;
3466 }
3467
3468 /*
3469 * ContentType type;
3470 * ProtocolVersion version;
3471 * uint16 epoch; // DTLS only
3472 * uint48 sequence_number; // DTLS only
3473 * uint16 length;
3474 *
3475 * Return 0 if header looks sane (and, for DTLS, the record is expected)
3476 * MBEDTLS_ERR_SSL_INVALID_RECORD if the header looks bad,
3477 * MBEDTLS_ERR_SSL_UNEXPECTED_RECORD (DTLS only) if sane but unexpected.
3478 *
3479 * With DTLS, mbedtls_ssl_read_record() will:
3480 * 1. proceed with the record if this function returns 0
3481 * 2. drop only the current record if this function returns UNEXPECTED_RECORD
3482 * 3. return CLIENT_RECONNECT if this function return that value
3483 * 4. drop the whole datagram if this function returns anything else.
3484 * Point 2 is needed when the peer is resending, and we have already received
3485 * the first record from a datagram but are still waiting for the others.
3486 */
3487 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_parse_record_header(mbedtls_ssl_context const * ssl,unsigned char * buf,size_t len,mbedtls_record * rec)3488 static int ssl_parse_record_header(mbedtls_ssl_context const *ssl,
3489 unsigned char *buf,
3490 size_t len,
3491 mbedtls_record *rec)
3492 {
3493 mbedtls_ssl_protocol_version tls_version;
3494
3495 size_t const rec_hdr_type_offset = 0;
3496 size_t const rec_hdr_type_len = 1;
3497
3498 size_t const rec_hdr_version_offset = rec_hdr_type_offset +
3499 rec_hdr_type_len;
3500 size_t const rec_hdr_version_len = 2;
3501
3502 size_t const rec_hdr_ctr_len = 8;
3503 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3504 uint32_t rec_epoch;
3505 size_t const rec_hdr_ctr_offset = rec_hdr_version_offset +
3506 rec_hdr_version_len;
3507
3508 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
3509 size_t const rec_hdr_cid_offset = rec_hdr_ctr_offset +
3510 rec_hdr_ctr_len;
3511 size_t rec_hdr_cid_len = 0;
3512 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
3513 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3514
3515 size_t rec_hdr_len_offset; /* To be determined */
3516 size_t const rec_hdr_len_len = 2;
3517
3518 /*
3519 * Check minimum lengths for record header.
3520 */
3521
3522 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3523 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
3524 rec_hdr_len_offset = rec_hdr_ctr_offset + rec_hdr_ctr_len;
3525 } else
3526 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3527 {
3528 rec_hdr_len_offset = rec_hdr_version_offset + rec_hdr_version_len;
3529 }
3530
3531 if (len < rec_hdr_len_offset + rec_hdr_len_len) {
3532 MBEDTLS_SSL_DEBUG_MSG(1,
3533 (
3534 "datagram of length %u too small to hold DTLS record header of length %u",
3535 (unsigned) len,
3536 (unsigned) (rec_hdr_len_len + rec_hdr_len_len)));
3537 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3538 }
3539
3540 /*
3541 * Parse and validate record content type
3542 */
3543
3544 rec->type = buf[rec_hdr_type_offset];
3545
3546 /* Check record content type */
3547 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
3548 rec->cid_len = 0;
3549
3550 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
3551 ssl->conf->cid_len != 0 &&
3552 rec->type == MBEDTLS_SSL_MSG_CID) {
3553 /* Shift pointers to account for record header including CID
3554 * struct {
3555 * ContentType outer_type = tls12_cid;
3556 * ProtocolVersion version;
3557 * uint16 epoch;
3558 * uint48 sequence_number;
3559 * opaque cid[cid_length]; // Additional field compared to
3560 * // default DTLS record format
3561 * uint16 length;
3562 * opaque enc_content[DTLSCiphertext.length];
3563 * } DTLSCiphertext;
3564 */
3565
3566 /* So far, we only support static CID lengths
3567 * fixed in the configuration. */
3568 rec_hdr_cid_len = ssl->conf->cid_len;
3569 rec_hdr_len_offset += rec_hdr_cid_len;
3570
3571 if (len < rec_hdr_len_offset + rec_hdr_len_len) {
3572 MBEDTLS_SSL_DEBUG_MSG(1,
3573 (
3574 "datagram of length %u too small to hold DTLS record header including CID, length %u",
3575 (unsigned) len,
3576 (unsigned) (rec_hdr_len_offset + rec_hdr_len_len)));
3577 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3578 }
3579
3580 /* configured CID len is guaranteed at most 255, see
3581 * MBEDTLS_SSL_CID_OUT_LEN_MAX in check_config.h */
3582 rec->cid_len = (uint8_t) rec_hdr_cid_len;
3583 memcpy(rec->cid, buf + rec_hdr_cid_offset, rec_hdr_cid_len);
3584 } else
3585 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
3586 {
3587 if (ssl_check_record_type(rec->type)) {
3588 MBEDTLS_SSL_DEBUG_MSG(1, ("unknown record type %u",
3589 (unsigned) rec->type));
3590 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3591 }
3592 }
3593
3594 /*
3595 * Parse and validate record version
3596 */
3597 rec->ver[0] = buf[rec_hdr_version_offset + 0];
3598 rec->ver[1] = buf[rec_hdr_version_offset + 1];
3599 tls_version = mbedtls_ssl_read_version(buf + rec_hdr_version_offset,
3600 ssl->conf->transport);
3601
3602 if (tls_version > ssl->conf->max_tls_version) {
3603 MBEDTLS_SSL_DEBUG_MSG(1, ("TLS version mismatch: got %u, expected max %u",
3604 (unsigned) tls_version,
3605 (unsigned) ssl->conf->max_tls_version));
3606
3607 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3608 }
3609 /*
3610 * Parse/Copy record sequence number.
3611 */
3612
3613 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3614 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
3615 /* Copy explicit record sequence number from input buffer. */
3616 memcpy(&rec->ctr[0], buf + rec_hdr_ctr_offset,
3617 rec_hdr_ctr_len);
3618 } else
3619 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3620 {
3621 /* Copy implicit record sequence number from SSL context structure. */
3622 memcpy(&rec->ctr[0], ssl->in_ctr, rec_hdr_ctr_len);
3623 }
3624
3625 /*
3626 * Parse record length.
3627 */
3628
3629 rec->data_offset = rec_hdr_len_offset + rec_hdr_len_len;
3630 rec->data_len = ((size_t) buf[rec_hdr_len_offset + 0] << 8) |
3631 ((size_t) buf[rec_hdr_len_offset + 1] << 0);
3632 MBEDTLS_SSL_DEBUG_BUF(4, "input record header", buf, rec->data_offset);
3633
3634 MBEDTLS_SSL_DEBUG_MSG(3, ("input record: msgtype = %u, "
3635 "version = [0x%x], msglen = %" MBEDTLS_PRINTF_SIZET,
3636 rec->type, (unsigned) tls_version, rec->data_len));
3637
3638 rec->buf = buf;
3639 rec->buf_len = rec->data_offset + rec->data_len;
3640
3641 if (rec->data_len == 0) {
3642 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3643 }
3644
3645 /*
3646 * DTLS-related tests.
3647 * Check epoch before checking length constraint because
3648 * the latter varies with the epoch. E.g., if a ChangeCipherSpec
3649 * message gets duplicated before the corresponding Finished message,
3650 * the second ChangeCipherSpec should be discarded because it belongs
3651 * to an old epoch, but not because its length is shorter than
3652 * the minimum record length for packets using the new record transform.
3653 * Note that these two kinds of failures are handled differently,
3654 * as an unexpected record is silently skipped but an invalid
3655 * record leads to the entire datagram being dropped.
3656 */
3657 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3658 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
3659 rec_epoch = (rec->ctr[0] << 8) | rec->ctr[1];
3660
3661 /* Check that the datagram is large enough to contain a record
3662 * of the advertised length. */
3663 if (len < rec->data_offset + rec->data_len) {
3664 MBEDTLS_SSL_DEBUG_MSG(1,
3665 (
3666 "Datagram of length %u too small to contain record of advertised length %u.",
3667 (unsigned) len,
3668 (unsigned) (rec->data_offset + rec->data_len)));
3669 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3670 }
3671
3672 /* Records from other, non-matching epochs are silently discarded.
3673 * (The case of same-port Client reconnects must be considered in
3674 * the caller). */
3675 if (rec_epoch != ssl->in_epoch) {
3676 MBEDTLS_SSL_DEBUG_MSG(1, ("record from another epoch: "
3677 "expected %u, received %lu",
3678 ssl->in_epoch, (unsigned long) rec_epoch));
3679
3680 /* Records from the next epoch are considered for buffering
3681 * (concretely: early Finished messages). */
3682 if (rec_epoch == (unsigned) ssl->in_epoch + 1) {
3683 MBEDTLS_SSL_DEBUG_MSG(2, ("Consider record for buffering"));
3684 return MBEDTLS_ERR_SSL_EARLY_MESSAGE;
3685 }
3686
3687 return MBEDTLS_ERR_SSL_UNEXPECTED_RECORD;
3688 }
3689 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
3690 /* For records from the correct epoch, check whether their
3691 * sequence number has been seen before. */
3692 else if (mbedtls_ssl_dtls_record_replay_check((mbedtls_ssl_context *) ssl,
3693 &rec->ctr[0]) != 0) {
3694 MBEDTLS_SSL_DEBUG_MSG(1, ("replayed record"));
3695 return MBEDTLS_ERR_SSL_UNEXPECTED_RECORD;
3696 }
3697 #endif
3698 }
3699 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3700
3701 return 0;
3702 }
3703
3704
3705 #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
3706 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_check_client_reconnect(mbedtls_ssl_context * ssl)3707 static int ssl_check_client_reconnect(mbedtls_ssl_context *ssl)
3708 {
3709 unsigned int rec_epoch = (ssl->in_ctr[0] << 8) | ssl->in_ctr[1];
3710
3711 /*
3712 * Check for an epoch 0 ClientHello. We can't use in_msg here to
3713 * access the first byte of record content (handshake type), as we
3714 * have an active transform (possibly iv_len != 0), so use the
3715 * fact that the record header len is 13 instead.
3716 */
3717 if (rec_epoch == 0 &&
3718 ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
3719 mbedtls_ssl_is_handshake_over(ssl) == 1 &&
3720 ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
3721 ssl->in_left > 13 &&
3722 ssl->in_buf[13] == MBEDTLS_SSL_HS_CLIENT_HELLO) {
3723 MBEDTLS_SSL_DEBUG_MSG(1, ("possible client reconnect "
3724 "from the same port"));
3725 return ssl_handle_possible_reconnect(ssl);
3726 }
3727
3728 return 0;
3729 }
3730 #endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
3731
3732 /*
3733 * If applicable, decrypt record content
3734 */
3735 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_prepare_record_content(mbedtls_ssl_context * ssl,mbedtls_record * rec)3736 static int ssl_prepare_record_content(mbedtls_ssl_context *ssl,
3737 mbedtls_record *rec)
3738 {
3739 int ret, done = 0;
3740
3741 MBEDTLS_SSL_DEBUG_BUF(4, "input record from network",
3742 rec->buf, rec->buf_len);
3743
3744 /*
3745 * In TLS 1.3, always treat ChangeCipherSpec records
3746 * as unencrypted. The only thing we do with them is
3747 * check the length and content and ignore them.
3748 */
3749 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
3750 if (ssl->transform_in != NULL &&
3751 ssl->transform_in->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
3752 if (rec->type == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) {
3753 done = 1;
3754 }
3755 }
3756 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
3757
3758 if (!done && ssl->transform_in != NULL) {
3759 unsigned char const old_msg_type = rec->type;
3760
3761 if ((ret = mbedtls_ssl_decrypt_buf(ssl, ssl->transform_in,
3762 rec)) != 0) {
3763 MBEDTLS_SSL_DEBUG_RET(1, "ssl_decrypt_buf", ret);
3764
3765 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
3766 if (ret == MBEDTLS_ERR_SSL_UNEXPECTED_CID &&
3767 ssl->conf->ignore_unexpected_cid
3768 == MBEDTLS_SSL_UNEXPECTED_CID_IGNORE) {
3769 MBEDTLS_SSL_DEBUG_MSG(3, ("ignoring unexpected CID"));
3770 ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
3771 }
3772 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
3773
3774 return ret;
3775 }
3776
3777 if (old_msg_type != rec->type) {
3778 MBEDTLS_SSL_DEBUG_MSG(4, ("record type after decrypt (before %d): %d",
3779 old_msg_type, rec->type));
3780 }
3781
3782 MBEDTLS_SSL_DEBUG_BUF(4, "input payload after decrypt",
3783 rec->buf + rec->data_offset, rec->data_len);
3784
3785 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
3786 /* We have already checked the record content type
3787 * in ssl_parse_record_header(), failing or silently
3788 * dropping the record in the case of an unknown type.
3789 *
3790 * Since with the use of CIDs, the record content type
3791 * might change during decryption, re-check the record
3792 * content type, but treat a failure as fatal this time. */
3793 if (ssl_check_record_type(rec->type)) {
3794 MBEDTLS_SSL_DEBUG_MSG(1, ("unknown record type"));
3795 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3796 }
3797 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
3798
3799 if (rec->data_len == 0) {
3800 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
3801 if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_2
3802 && rec->type != MBEDTLS_SSL_MSG_APPLICATION_DATA) {
3803 /* TLS v1.2 explicitly disallows zero-length messages which are not application data */
3804 MBEDTLS_SSL_DEBUG_MSG(1, ("invalid zero-length message type: %d", ssl->in_msgtype));
3805 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3806 }
3807 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
3808
3809 ssl->nb_zero++;
3810
3811 /*
3812 * Three or more empty messages may be a DoS attack
3813 * (excessive CPU consumption).
3814 */
3815 if (ssl->nb_zero > 3) {
3816 MBEDTLS_SSL_DEBUG_MSG(1, ("received four consecutive empty "
3817 "messages, possible DoS attack"));
3818 /* Treat the records as if they were not properly authenticated,
3819 * thereby failing the connection if we see more than allowed
3820 * by the configured bad MAC threshold. */
3821 return MBEDTLS_ERR_SSL_INVALID_MAC;
3822 }
3823 } else {
3824 ssl->nb_zero = 0;
3825 }
3826
3827 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3828 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
3829 ; /* in_ctr read from peer, not maintained internally */
3830 } else
3831 #endif
3832 {
3833 unsigned i;
3834 for (i = MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
3835 i > mbedtls_ssl_ep_len(ssl); i--) {
3836 if (++ssl->in_ctr[i - 1] != 0) {
3837 break;
3838 }
3839 }
3840
3841 /* The loop goes to its end iff the counter is wrapping */
3842 if (i == mbedtls_ssl_ep_len(ssl)) {
3843 MBEDTLS_SSL_DEBUG_MSG(1, ("incoming message counter would wrap"));
3844 return MBEDTLS_ERR_SSL_COUNTER_WRAPPING;
3845 }
3846 }
3847
3848 }
3849
3850 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
3851 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
3852 mbedtls_ssl_dtls_replay_update(ssl);
3853 }
3854 #endif
3855
3856 /* Check actual (decrypted) record content length against
3857 * configured maximum. */
3858 if (rec->data_len > MBEDTLS_SSL_IN_CONTENT_LEN) {
3859 MBEDTLS_SSL_DEBUG_MSG(1, ("bad message length"));
3860 return MBEDTLS_ERR_SSL_INVALID_RECORD;
3861 }
3862
3863 return 0;
3864 }
3865
3866 /*
3867 * Read a record.
3868 *
3869 * Silently ignore non-fatal alert (and for DTLS, invalid records as well,
3870 * RFC 6347 4.1.2.7) and continue reading until a valid record is found.
3871 *
3872 */
3873
3874 /* Helper functions for mbedtls_ssl_read_record(). */
3875 MBEDTLS_CHECK_RETURN_CRITICAL
3876 static int ssl_consume_current_message(mbedtls_ssl_context *ssl);
3877 MBEDTLS_CHECK_RETURN_CRITICAL
3878 static int ssl_get_next_record(mbedtls_ssl_context *ssl);
3879 MBEDTLS_CHECK_RETURN_CRITICAL
3880 static int ssl_record_is_in_progress(mbedtls_ssl_context *ssl);
3881
mbedtls_ssl_read_record(mbedtls_ssl_context * ssl,unsigned update_hs_digest)3882 int mbedtls_ssl_read_record(mbedtls_ssl_context *ssl,
3883 unsigned update_hs_digest)
3884 {
3885 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
3886
3887 MBEDTLS_SSL_DEBUG_MSG(2, ("=> read record"));
3888
3889 if (ssl->keep_current_message == 0) {
3890 do {
3891
3892 ret = ssl_consume_current_message(ssl);
3893 if (ret != 0) {
3894 return ret;
3895 }
3896
3897 if (ssl_record_is_in_progress(ssl) == 0) {
3898 int dtls_have_buffered = 0;
3899 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3900
3901 /* We only check for buffered messages if the
3902 * current datagram is fully consumed. */
3903 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
3904 ssl_next_record_is_in_datagram(ssl) == 0) {
3905 if (ssl_load_buffered_message(ssl) == 0) {
3906 dtls_have_buffered = 1;
3907 }
3908 }
3909
3910 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3911 if (dtls_have_buffered == 0) {
3912 ret = ssl_get_next_record(ssl);
3913 if (ret == MBEDTLS_ERR_SSL_CONTINUE_PROCESSING) {
3914 continue;
3915 }
3916
3917 if (ret != 0) {
3918 MBEDTLS_SSL_DEBUG_RET(1, ("ssl_get_next_record"), ret);
3919 return ret;
3920 }
3921 }
3922 }
3923
3924 ret = mbedtls_ssl_handle_message_type(ssl);
3925
3926 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3927 if (ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE) {
3928 /* Buffer future message */
3929 ret = ssl_buffer_message(ssl);
3930 if (ret != 0) {
3931 return ret;
3932 }
3933
3934 ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
3935 }
3936 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3937
3938 } while (MBEDTLS_ERR_SSL_NON_FATAL == ret ||
3939 MBEDTLS_ERR_SSL_CONTINUE_PROCESSING == ret);
3940
3941 if (0 != ret) {
3942 MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_handle_message_type"), ret);
3943 return ret;
3944 }
3945
3946 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
3947 update_hs_digest == 1) {
3948 ret = mbedtls_ssl_update_handshake_status(ssl);
3949 if (0 != ret) {
3950 MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_update_handshake_status"), ret);
3951 return ret;
3952 }
3953 }
3954 } else {
3955 MBEDTLS_SSL_DEBUG_MSG(2, ("reuse previously read message"));
3956 ssl->keep_current_message = 0;
3957 }
3958
3959 MBEDTLS_SSL_DEBUG_MSG(2, ("<= read record"));
3960
3961 return 0;
3962 }
3963
3964 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3965 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_next_record_is_in_datagram(mbedtls_ssl_context * ssl)3966 static int ssl_next_record_is_in_datagram(mbedtls_ssl_context *ssl)
3967 {
3968 if (ssl->in_left > ssl->next_record_offset) {
3969 return 1;
3970 }
3971
3972 return 0;
3973 }
3974
3975 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_load_buffered_message(mbedtls_ssl_context * ssl)3976 static int ssl_load_buffered_message(mbedtls_ssl_context *ssl)
3977 {
3978 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
3979 mbedtls_ssl_hs_buffer *hs_buf;
3980 int ret = 0;
3981
3982 if (hs == NULL) {
3983 return -1;
3984 }
3985
3986 MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_load_buffered_message"));
3987
3988 if (ssl->state == MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC ||
3989 ssl->state == MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC) {
3990 /* Check if we have seen a ChangeCipherSpec before.
3991 * If yes, synthesize a CCS record. */
3992 if (!hs->buffering.seen_ccs) {
3993 MBEDTLS_SSL_DEBUG_MSG(2, ("CCS not seen in the current flight"));
3994 ret = -1;
3995 goto exit;
3996 }
3997
3998 MBEDTLS_SSL_DEBUG_MSG(2, ("Injecting buffered CCS message"));
3999 ssl->in_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC;
4000 ssl->in_msglen = 1;
4001 ssl->in_msg[0] = 1;
4002
4003 /* As long as they are equal, the exact value doesn't matter. */
4004 ssl->in_left = 0;
4005 ssl->next_record_offset = 0;
4006
4007 hs->buffering.seen_ccs = 0;
4008 goto exit;
4009 }
4010
4011 #if defined(MBEDTLS_DEBUG_C)
4012 /* Debug only */
4013 {
4014 unsigned offset;
4015 for (offset = 1; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++) {
4016 hs_buf = &hs->buffering.hs[offset];
4017 if (hs_buf->is_valid == 1) {
4018 MBEDTLS_SSL_DEBUG_MSG(2, ("Future message with sequence number %u %s buffered.",
4019 hs->in_msg_seq + offset,
4020 hs_buf->is_complete ? "fully" : "partially"));
4021 }
4022 }
4023 }
4024 #endif /* MBEDTLS_DEBUG_C */
4025
4026 /* Check if we have buffered and/or fully reassembled the
4027 * next handshake message. */
4028 hs_buf = &hs->buffering.hs[0];
4029 if ((hs_buf->is_valid == 1) && (hs_buf->is_complete == 1)) {
4030 /* Synthesize a record containing the buffered HS message. */
4031 size_t msg_len = (hs_buf->data[1] << 16) |
4032 (hs_buf->data[2] << 8) |
4033 hs_buf->data[3];
4034
4035 /* Double-check that we haven't accidentally buffered
4036 * a message that doesn't fit into the input buffer. */
4037 if (msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN) {
4038 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
4039 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
4040 }
4041
4042 MBEDTLS_SSL_DEBUG_MSG(2, ("Next handshake message has been buffered - load"));
4043 MBEDTLS_SSL_DEBUG_BUF(3, "Buffered handshake message (incl. header)",
4044 hs_buf->data, msg_len + 12);
4045
4046 ssl->in_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
4047 ssl->in_hslen = msg_len + 12;
4048 ssl->in_msglen = msg_len + 12;
4049 memcpy(ssl->in_msg, hs_buf->data, ssl->in_hslen);
4050
4051 ret = 0;
4052 goto exit;
4053 } else {
4054 MBEDTLS_SSL_DEBUG_MSG(2, ("Next handshake message %u not or only partially bufffered",
4055 hs->in_msg_seq));
4056 }
4057
4058 ret = -1;
4059
4060 exit:
4061
4062 MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_load_buffered_message"));
4063 return ret;
4064 }
4065
4066 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_buffer_make_space(mbedtls_ssl_context * ssl,size_t desired)4067 static int ssl_buffer_make_space(mbedtls_ssl_context *ssl,
4068 size_t desired)
4069 {
4070 int offset;
4071 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
4072 MBEDTLS_SSL_DEBUG_MSG(2, ("Attempt to free buffered messages to have %u bytes available",
4073 (unsigned) desired));
4074
4075 /* Get rid of future records epoch first, if such exist. */
4076 ssl_free_buffered_record(ssl);
4077
4078 /* Check if we have enough space available now. */
4079 if (desired <= (MBEDTLS_SSL_DTLS_MAX_BUFFERING -
4080 hs->buffering.total_bytes_buffered)) {
4081 MBEDTLS_SSL_DEBUG_MSG(2, ("Enough space available after freeing future epoch record"));
4082 return 0;
4083 }
4084
4085 /* We don't have enough space to buffer the next expected handshake
4086 * message. Remove buffers used for future messages to gain space,
4087 * starting with the most distant one. */
4088 for (offset = MBEDTLS_SSL_MAX_BUFFERED_HS - 1;
4089 offset >= 0; offset--) {
4090 MBEDTLS_SSL_DEBUG_MSG(2,
4091 (
4092 "Free buffering slot %d to make space for reassembly of next handshake message",
4093 offset));
4094
4095 ssl_buffering_free_slot(ssl, (uint8_t) offset);
4096
4097 /* Check if we have enough space available now. */
4098 if (desired <= (MBEDTLS_SSL_DTLS_MAX_BUFFERING -
4099 hs->buffering.total_bytes_buffered)) {
4100 MBEDTLS_SSL_DEBUG_MSG(2, ("Enough space available after freeing buffered HS messages"));
4101 return 0;
4102 }
4103 }
4104
4105 return -1;
4106 }
4107
4108 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_buffer_message(mbedtls_ssl_context * ssl)4109 static int ssl_buffer_message(mbedtls_ssl_context *ssl)
4110 {
4111 int ret = 0;
4112 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
4113
4114 if (hs == NULL) {
4115 return 0;
4116 }
4117
4118 MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_buffer_message"));
4119
4120 switch (ssl->in_msgtype) {
4121 case MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC:
4122 MBEDTLS_SSL_DEBUG_MSG(2, ("Remember CCS message"));
4123
4124 hs->buffering.seen_ccs = 1;
4125 break;
4126
4127 case MBEDTLS_SSL_MSG_HANDSHAKE:
4128 {
4129 unsigned recv_msg_seq_offset;
4130 unsigned recv_msg_seq = (ssl->in_msg[4] << 8) | ssl->in_msg[5];
4131 mbedtls_ssl_hs_buffer *hs_buf;
4132 size_t msg_len = ssl->in_hslen - 12;
4133
4134 /* We should never receive an old handshake
4135 * message - double-check nonetheless. */
4136 if (recv_msg_seq < ssl->handshake->in_msg_seq) {
4137 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
4138 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
4139 }
4140
4141 recv_msg_seq_offset = recv_msg_seq - ssl->handshake->in_msg_seq;
4142 if (recv_msg_seq_offset >= MBEDTLS_SSL_MAX_BUFFERED_HS) {
4143 /* Silently ignore -- message too far in the future */
4144 MBEDTLS_SSL_DEBUG_MSG(2,
4145 ("Ignore future HS message with sequence number %u, "
4146 "buffering window %u - %u",
4147 recv_msg_seq, ssl->handshake->in_msg_seq,
4148 ssl->handshake->in_msg_seq + MBEDTLS_SSL_MAX_BUFFERED_HS -
4149 1));
4150
4151 goto exit;
4152 }
4153
4154 MBEDTLS_SSL_DEBUG_MSG(2, ("Buffering HS message with sequence number %u, offset %u ",
4155 recv_msg_seq, recv_msg_seq_offset));
4156
4157 hs_buf = &hs->buffering.hs[recv_msg_seq_offset];
4158
4159 /* Check if the buffering for this seq nr has already commenced. */
4160 if (!hs_buf->is_valid) {
4161 size_t reassembly_buf_sz;
4162
4163 hs_buf->is_fragmented =
4164 (ssl_hs_is_proper_fragment(ssl) == 1);
4165
4166 /* We copy the message back into the input buffer
4167 * after reassembly, so check that it's not too large.
4168 * This is an implementation-specific limitation
4169 * and not one from the standard, hence it is not
4170 * checked in ssl_check_hs_header(). */
4171 if (msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN) {
4172 /* Ignore message */
4173 goto exit;
4174 }
4175
4176 /* Check if we have enough space to buffer the message. */
4177 if (hs->buffering.total_bytes_buffered >
4178 MBEDTLS_SSL_DTLS_MAX_BUFFERING) {
4179 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
4180 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
4181 }
4182
4183 reassembly_buf_sz = ssl_get_reassembly_buffer_size(msg_len,
4184 hs_buf->is_fragmented);
4185
4186 if (reassembly_buf_sz > (MBEDTLS_SSL_DTLS_MAX_BUFFERING -
4187 hs->buffering.total_bytes_buffered)) {
4188 if (recv_msg_seq_offset > 0) {
4189 /* If we can't buffer a future message because
4190 * of space limitations -- ignore. */
4191 MBEDTLS_SSL_DEBUG_MSG(2,
4192 ("Buffering of future message of size %"
4193 MBEDTLS_PRINTF_SIZET
4194 " would exceed the compile-time limit %"
4195 MBEDTLS_PRINTF_SIZET
4196 " (already %" MBEDTLS_PRINTF_SIZET
4197 " bytes buffered) -- ignore\n",
4198 msg_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
4199 hs->buffering.total_bytes_buffered));
4200 goto exit;
4201 } else {
4202 MBEDTLS_SSL_DEBUG_MSG(2,
4203 ("Buffering of future message of size %"
4204 MBEDTLS_PRINTF_SIZET
4205 " would exceed the compile-time limit %"
4206 MBEDTLS_PRINTF_SIZET
4207 " (already %" MBEDTLS_PRINTF_SIZET
4208 " bytes buffered) -- attempt to make space by freeing buffered future messages\n",
4209 msg_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
4210 hs->buffering.total_bytes_buffered));
4211 }
4212
4213 if (ssl_buffer_make_space(ssl, reassembly_buf_sz) != 0) {
4214 MBEDTLS_SSL_DEBUG_MSG(2,
4215 ("Reassembly of next message of size %"
4216 MBEDTLS_PRINTF_SIZET
4217 " (%" MBEDTLS_PRINTF_SIZET
4218 " with bitmap) would exceed"
4219 " the compile-time limit %"
4220 MBEDTLS_PRINTF_SIZET
4221 " (already %" MBEDTLS_PRINTF_SIZET
4222 " bytes buffered) -- fail\n",
4223 msg_len,
4224 reassembly_buf_sz,
4225 (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
4226 hs->buffering.total_bytes_buffered));
4227 ret = MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
4228 goto exit;
4229 }
4230 }
4231
4232 MBEDTLS_SSL_DEBUG_MSG(2,
4233 ("initialize reassembly, total length = %"
4234 MBEDTLS_PRINTF_SIZET,
4235 msg_len));
4236
4237 hs_buf->data = mbedtls_calloc(1, reassembly_buf_sz);
4238 if (hs_buf->data == NULL) {
4239 ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
4240 goto exit;
4241 }
4242 hs_buf->data_len = reassembly_buf_sz;
4243
4244 /* Prepare final header: copy msg_type, length and message_seq,
4245 * then add standardised fragment_offset and fragment_length */
4246 memcpy(hs_buf->data, ssl->in_msg, 6);
4247 memset(hs_buf->data + 6, 0, 3);
4248 memcpy(hs_buf->data + 9, hs_buf->data + 1, 3);
4249
4250 hs_buf->is_valid = 1;
4251
4252 hs->buffering.total_bytes_buffered += reassembly_buf_sz;
4253 } else {
4254 /* Make sure msg_type and length are consistent */
4255 if (memcmp(hs_buf->data, ssl->in_msg, 4) != 0) {
4256 MBEDTLS_SSL_DEBUG_MSG(1, ("Fragment header mismatch - ignore"));
4257 /* Ignore */
4258 goto exit;
4259 }
4260 }
4261
4262 if (!hs_buf->is_complete) {
4263 size_t frag_len, frag_off;
4264 unsigned char * const msg = hs_buf->data + 12;
4265
4266 /*
4267 * Check and copy current fragment
4268 */
4269
4270 /* Validation of header fields already done in
4271 * mbedtls_ssl_prepare_handshake_record(). */
4272 frag_off = ssl_get_hs_frag_off(ssl);
4273 frag_len = ssl_get_hs_frag_len(ssl);
4274
4275 MBEDTLS_SSL_DEBUG_MSG(2, ("adding fragment, offset = %" MBEDTLS_PRINTF_SIZET
4276 ", length = %" MBEDTLS_PRINTF_SIZET,
4277 frag_off, frag_len));
4278 memcpy(msg + frag_off, ssl->in_msg + 12, frag_len);
4279
4280 if (hs_buf->is_fragmented) {
4281 unsigned char * const bitmask = msg + msg_len;
4282 ssl_bitmask_set(bitmask, frag_off, frag_len);
4283 hs_buf->is_complete = (ssl_bitmask_check(bitmask,
4284 msg_len) == 0);
4285 } else {
4286 hs_buf->is_complete = 1;
4287 }
4288
4289 MBEDTLS_SSL_DEBUG_MSG(2, ("message %scomplete",
4290 hs_buf->is_complete ? "" : "not yet "));
4291 }
4292
4293 break;
4294 }
4295
4296 default:
4297 /* We don't buffer other types of messages. */
4298 break;
4299 }
4300
4301 exit:
4302
4303 MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_buffer_message"));
4304 return ret;
4305 }
4306 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4307
4308 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_consume_current_message(mbedtls_ssl_context * ssl)4309 static int ssl_consume_current_message(mbedtls_ssl_context *ssl)
4310 {
4311 /*
4312 * Consume last content-layer message and potentially
4313 * update in_msglen which keeps track of the contents'
4314 * consumption state.
4315 *
4316 * (1) Handshake messages:
4317 * Remove last handshake message, move content
4318 * and adapt in_msglen.
4319 *
4320 * (2) Alert messages:
4321 * Consume whole record content, in_msglen = 0.
4322 *
4323 * (3) Change cipher spec:
4324 * Consume whole record content, in_msglen = 0.
4325 *
4326 * (4) Application data:
4327 * Don't do anything - the record layer provides
4328 * the application data as a stream transport
4329 * and consumes through mbedtls_ssl_read only.
4330 *
4331 */
4332
4333 /* Case (1): Handshake messages */
4334 if (ssl->in_hslen != 0) {
4335 /* Hard assertion to be sure that no application data
4336 * is in flight, as corrupting ssl->in_msglen during
4337 * ssl->in_offt != NULL is fatal. */
4338 if (ssl->in_offt != NULL) {
4339 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
4340 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
4341 }
4342
4343 /*
4344 * Get next Handshake message in the current record
4345 */
4346
4347 /* Notes:
4348 * (1) in_hslen is not necessarily the size of the
4349 * current handshake content: If DTLS handshake
4350 * fragmentation is used, that's the fragment
4351 * size instead. Using the total handshake message
4352 * size here is faulty and should be changed at
4353 * some point.
4354 * (2) While it doesn't seem to cause problems, one
4355 * has to be very careful not to assume that in_hslen
4356 * is always <= in_msglen in a sensible communication.
4357 * Again, it's wrong for DTLS handshake fragmentation.
4358 * The following check is therefore mandatory, and
4359 * should not be treated as a silently corrected assertion.
4360 * Additionally, ssl->in_hslen might be arbitrarily out of
4361 * bounds after handling a DTLS message with an unexpected
4362 * sequence number, see mbedtls_ssl_prepare_handshake_record.
4363 */
4364 if (ssl->in_hslen < ssl->in_msglen) {
4365 ssl->in_msglen -= ssl->in_hslen;
4366 memmove(ssl->in_msg, ssl->in_msg + ssl->in_hslen,
4367 ssl->in_msglen);
4368
4369 MBEDTLS_SSL_DEBUG_BUF(4, "remaining content in record",
4370 ssl->in_msg, ssl->in_msglen);
4371 } else {
4372 ssl->in_msglen = 0;
4373 }
4374
4375 ssl->in_hslen = 0;
4376 }
4377 /* Case (4): Application data */
4378 else if (ssl->in_offt != NULL) {
4379 return 0;
4380 }
4381 /* Everything else (CCS & Alerts) */
4382 else {
4383 ssl->in_msglen = 0;
4384 }
4385
4386 return 0;
4387 }
4388
4389 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_record_is_in_progress(mbedtls_ssl_context * ssl)4390 static int ssl_record_is_in_progress(mbedtls_ssl_context *ssl)
4391 {
4392 if (ssl->in_msglen > 0) {
4393 return 1;
4394 }
4395
4396 return 0;
4397 }
4398
4399 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4400
ssl_free_buffered_record(mbedtls_ssl_context * ssl)4401 static void ssl_free_buffered_record(mbedtls_ssl_context *ssl)
4402 {
4403 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
4404 if (hs == NULL) {
4405 return;
4406 }
4407
4408 if (hs->buffering.future_record.data != NULL) {
4409 hs->buffering.total_bytes_buffered -=
4410 hs->buffering.future_record.len;
4411
4412 mbedtls_free(hs->buffering.future_record.data);
4413 hs->buffering.future_record.data = NULL;
4414 }
4415 }
4416
4417 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_load_buffered_record(mbedtls_ssl_context * ssl)4418 static int ssl_load_buffered_record(mbedtls_ssl_context *ssl)
4419 {
4420 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
4421 unsigned char *rec;
4422 size_t rec_len;
4423 unsigned rec_epoch;
4424 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
4425 size_t in_buf_len = ssl->in_buf_len;
4426 #else
4427 size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN;
4428 #endif
4429 if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
4430 return 0;
4431 }
4432
4433 if (hs == NULL) {
4434 return 0;
4435 }
4436
4437 rec = hs->buffering.future_record.data;
4438 rec_len = hs->buffering.future_record.len;
4439 rec_epoch = hs->buffering.future_record.epoch;
4440
4441 if (rec == NULL) {
4442 return 0;
4443 }
4444
4445 /* Only consider loading future records if the
4446 * input buffer is empty. */
4447 if (ssl_next_record_is_in_datagram(ssl) == 1) {
4448 return 0;
4449 }
4450
4451 MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_load_buffered_record"));
4452
4453 if (rec_epoch != ssl->in_epoch) {
4454 MBEDTLS_SSL_DEBUG_MSG(2, ("Buffered record not from current epoch."));
4455 goto exit;
4456 }
4457
4458 MBEDTLS_SSL_DEBUG_MSG(2, ("Found buffered record from current epoch - load"));
4459
4460 /* Double-check that the record is not too large */
4461 if (rec_len > in_buf_len - (size_t) (ssl->in_hdr - ssl->in_buf)) {
4462 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
4463 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
4464 }
4465
4466 memcpy(ssl->in_hdr, rec, rec_len);
4467 ssl->in_left = rec_len;
4468 ssl->next_record_offset = 0;
4469
4470 ssl_free_buffered_record(ssl);
4471
4472 exit:
4473 MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_load_buffered_record"));
4474 return 0;
4475 }
4476
4477 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_buffer_future_record(mbedtls_ssl_context * ssl,mbedtls_record const * rec)4478 static int ssl_buffer_future_record(mbedtls_ssl_context *ssl,
4479 mbedtls_record const *rec)
4480 {
4481 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
4482
4483 /* Don't buffer future records outside handshakes. */
4484 if (hs == NULL) {
4485 return 0;
4486 }
4487
4488 /* Only buffer handshake records (we are only interested
4489 * in Finished messages). */
4490 if (rec->type != MBEDTLS_SSL_MSG_HANDSHAKE) {
4491 return 0;
4492 }
4493
4494 /* Don't buffer more than one future epoch record. */
4495 if (hs->buffering.future_record.data != NULL) {
4496 return 0;
4497 }
4498
4499 /* Don't buffer record if there's not enough buffering space remaining. */
4500 if (rec->buf_len > (MBEDTLS_SSL_DTLS_MAX_BUFFERING -
4501 hs->buffering.total_bytes_buffered)) {
4502 MBEDTLS_SSL_DEBUG_MSG(2, ("Buffering of future epoch record of size %" MBEDTLS_PRINTF_SIZET
4503 " would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET
4504 " (already %" MBEDTLS_PRINTF_SIZET
4505 " bytes buffered) -- ignore\n",
4506 rec->buf_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
4507 hs->buffering.total_bytes_buffered));
4508 return 0;
4509 }
4510
4511 /* Buffer record */
4512 MBEDTLS_SSL_DEBUG_MSG(2, ("Buffer record from epoch %u",
4513 ssl->in_epoch + 1U));
4514 MBEDTLS_SSL_DEBUG_BUF(3, "Buffered record", rec->buf, rec->buf_len);
4515
4516 /* ssl_parse_record_header() only considers records
4517 * of the next epoch as candidates for buffering. */
4518 hs->buffering.future_record.epoch = ssl->in_epoch + 1;
4519 hs->buffering.future_record.len = rec->buf_len;
4520
4521 hs->buffering.future_record.data =
4522 mbedtls_calloc(1, hs->buffering.future_record.len);
4523 if (hs->buffering.future_record.data == NULL) {
4524 /* If we run out of RAM trying to buffer a
4525 * record from the next epoch, just ignore. */
4526 return 0;
4527 }
4528
4529 memcpy(hs->buffering.future_record.data, rec->buf, rec->buf_len);
4530
4531 hs->buffering.total_bytes_buffered += rec->buf_len;
4532 return 0;
4533 }
4534
4535 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4536
4537 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_get_next_record(mbedtls_ssl_context * ssl)4538 static int ssl_get_next_record(mbedtls_ssl_context *ssl)
4539 {
4540 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
4541 mbedtls_record rec;
4542
4543 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4544 /* We might have buffered a future record; if so,
4545 * and if the epoch matches now, load it.
4546 * On success, this call will set ssl->in_left to
4547 * the length of the buffered record, so that
4548 * the calls to ssl_fetch_input() below will
4549 * essentially be no-ops. */
4550 ret = ssl_load_buffered_record(ssl);
4551 if (ret != 0) {
4552 return ret;
4553 }
4554 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4555
4556 /* Ensure that we have enough space available for the default form
4557 * of TLS / DTLS record headers (5 Bytes for TLS, 13 Bytes for DTLS,
4558 * with no space for CIDs counted in). */
4559 ret = mbedtls_ssl_fetch_input(ssl, mbedtls_ssl_in_hdr_len(ssl));
4560 if (ret != 0) {
4561 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_fetch_input", ret);
4562 return ret;
4563 }
4564
4565 ret = ssl_parse_record_header(ssl, ssl->in_hdr, ssl->in_left, &rec);
4566 if (ret != 0) {
4567 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4568 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
4569 if (ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE) {
4570 ret = ssl_buffer_future_record(ssl, &rec);
4571 if (ret != 0) {
4572 return ret;
4573 }
4574
4575 /* Fall through to handling of unexpected records */
4576 ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD;
4577 }
4578
4579 if (ret == MBEDTLS_ERR_SSL_UNEXPECTED_RECORD) {
4580 #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
4581 /* Reset in pointers to default state for TLS/DTLS records,
4582 * assuming no CID and no offset between record content and
4583 * record plaintext. */
4584 mbedtls_ssl_update_in_pointers(ssl);
4585
4586 /* Setup internal message pointers from record structure. */
4587 ssl->in_msgtype = rec.type;
4588 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
4589 ssl->in_len = ssl->in_cid + rec.cid_len;
4590 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
4591 ssl->in_iv = ssl->in_msg = ssl->in_len + 2;
4592 ssl->in_msglen = rec.data_len;
4593
4594 ret = ssl_check_client_reconnect(ssl);
4595 MBEDTLS_SSL_DEBUG_RET(2, "ssl_check_client_reconnect", ret);
4596 if (ret != 0) {
4597 return ret;
4598 }
4599 #endif
4600
4601 /* Skip unexpected record (but not whole datagram) */
4602 ssl->next_record_offset = rec.buf_len;
4603
4604 MBEDTLS_SSL_DEBUG_MSG(1, ("discarding unexpected record "
4605 "(header)"));
4606 } else {
4607 /* Skip invalid record and the rest of the datagram */
4608 ssl->next_record_offset = 0;
4609 ssl->in_left = 0;
4610
4611 MBEDTLS_SSL_DEBUG_MSG(1, ("discarding invalid record "
4612 "(header)"));
4613 }
4614
4615 /* Get next record */
4616 return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
4617 } else
4618 #endif
4619 {
4620 return ret;
4621 }
4622 }
4623
4624 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4625 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
4626 /* Remember offset of next record within datagram. */
4627 ssl->next_record_offset = rec.buf_len;
4628 if (ssl->next_record_offset < ssl->in_left) {
4629 MBEDTLS_SSL_DEBUG_MSG(3, ("more than one record within datagram"));
4630 }
4631 } else
4632 #endif
4633 {
4634 /*
4635 * Fetch record contents from underlying transport.
4636 */
4637 ret = mbedtls_ssl_fetch_input(ssl, rec.buf_len);
4638 if (ret != 0) {
4639 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_fetch_input", ret);
4640 return ret;
4641 }
4642
4643 ssl->in_left = 0;
4644 }
4645
4646 /*
4647 * Decrypt record contents.
4648 */
4649
4650 if ((ret = ssl_prepare_record_content(ssl, &rec)) != 0) {
4651 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4652 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
4653 /* Silently discard invalid records */
4654 if (ret == MBEDTLS_ERR_SSL_INVALID_MAC) {
4655 /* Except when waiting for Finished as a bad mac here
4656 * probably means something went wrong in the handshake
4657 * (eg wrong psk used, mitm downgrade attempt, etc.) */
4658 if (ssl->state == MBEDTLS_SSL_CLIENT_FINISHED ||
4659 ssl->state == MBEDTLS_SSL_SERVER_FINISHED) {
4660 #if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES)
4661 if (ret == MBEDTLS_ERR_SSL_INVALID_MAC) {
4662 mbedtls_ssl_send_alert_message(ssl,
4663 MBEDTLS_SSL_ALERT_LEVEL_FATAL,
4664 MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC);
4665 }
4666 #endif
4667 return ret;
4668 }
4669
4670 if (ssl->conf->badmac_limit != 0 &&
4671 ++ssl->badmac_seen >= ssl->conf->badmac_limit) {
4672 MBEDTLS_SSL_DEBUG_MSG(1, ("too many records with bad MAC"));
4673 return MBEDTLS_ERR_SSL_INVALID_MAC;
4674 }
4675
4676 /* As above, invalid records cause
4677 * dismissal of the whole datagram. */
4678
4679 ssl->next_record_offset = 0;
4680 ssl->in_left = 0;
4681
4682 MBEDTLS_SSL_DEBUG_MSG(1, ("discarding invalid record (mac)"));
4683 return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
4684 }
4685
4686 return ret;
4687 } else
4688 #endif
4689 {
4690 /* Error out (and send alert) on invalid records */
4691 #if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES)
4692 if (ret == MBEDTLS_ERR_SSL_INVALID_MAC) {
4693 mbedtls_ssl_send_alert_message(ssl,
4694 MBEDTLS_SSL_ALERT_LEVEL_FATAL,
4695 MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC);
4696 }
4697 #endif
4698 return ret;
4699 }
4700 }
4701
4702
4703 /* Reset in pointers to default state for TLS/DTLS records,
4704 * assuming no CID and no offset between record content and
4705 * record plaintext. */
4706 mbedtls_ssl_update_in_pointers(ssl);
4707 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
4708 ssl->in_len = ssl->in_cid + rec.cid_len;
4709 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
4710 ssl->in_iv = ssl->in_len + 2;
4711
4712 /* The record content type may change during decryption,
4713 * so re-read it. */
4714 ssl->in_msgtype = rec.type;
4715 /* Also update the input buffer, because unfortunately
4716 * the server-side ssl_parse_client_hello() reparses the
4717 * record header when receiving a ClientHello initiating
4718 * a renegotiation. */
4719 ssl->in_hdr[0] = rec.type;
4720 ssl->in_msg = rec.buf + rec.data_offset;
4721 ssl->in_msglen = rec.data_len;
4722 MBEDTLS_PUT_UINT16_BE(rec.data_len, ssl->in_len, 0);
4723
4724 return 0;
4725 }
4726
mbedtls_ssl_handle_message_type(mbedtls_ssl_context * ssl)4727 int mbedtls_ssl_handle_message_type(mbedtls_ssl_context *ssl)
4728 {
4729 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
4730
4731 /*
4732 * Handle particular types of records
4733 */
4734 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE) {
4735 if ((ret = mbedtls_ssl_prepare_handshake_record(ssl)) != 0) {
4736 return ret;
4737 }
4738 }
4739
4740 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) {
4741 if (ssl->in_msglen != 1) {
4742 MBEDTLS_SSL_DEBUG_MSG(1, ("invalid CCS message, len: %" MBEDTLS_PRINTF_SIZET,
4743 ssl->in_msglen));
4744 return MBEDTLS_ERR_SSL_INVALID_RECORD;
4745 }
4746
4747 if (ssl->in_msg[0] != 1) {
4748 MBEDTLS_SSL_DEBUG_MSG(1, ("invalid CCS message, content: %02x",
4749 ssl->in_msg[0]));
4750 return MBEDTLS_ERR_SSL_INVALID_RECORD;
4751 }
4752
4753 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4754 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
4755 ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC &&
4756 ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC) {
4757 if (ssl->handshake == NULL) {
4758 MBEDTLS_SSL_DEBUG_MSG(1, ("dropping ChangeCipherSpec outside handshake"));
4759 return MBEDTLS_ERR_SSL_UNEXPECTED_RECORD;
4760 }
4761
4762 MBEDTLS_SSL_DEBUG_MSG(1, ("received out-of-order ChangeCipherSpec - remember"));
4763 return MBEDTLS_ERR_SSL_EARLY_MESSAGE;
4764 }
4765 #endif
4766
4767 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
4768 if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
4769 #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
4770 MBEDTLS_SSL_DEBUG_MSG(1,
4771 ("Ignore ChangeCipherSpec in TLS 1.3 compatibility mode"));
4772 return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
4773 #else
4774 MBEDTLS_SSL_DEBUG_MSG(1,
4775 ("ChangeCipherSpec invalid in TLS 1.3 without compatibility mode"));
4776 return MBEDTLS_ERR_SSL_INVALID_RECORD;
4777 #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
4778 }
4779 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
4780 }
4781
4782 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT) {
4783 if (ssl->in_msglen != 2) {
4784 /* Note: Standard allows for more than one 2 byte alert
4785 to be packed in a single message, but Mbed TLS doesn't
4786 currently support this. */
4787 MBEDTLS_SSL_DEBUG_MSG(1, ("invalid alert message, len: %" MBEDTLS_PRINTF_SIZET,
4788 ssl->in_msglen));
4789 return MBEDTLS_ERR_SSL_INVALID_RECORD;
4790 }
4791
4792 MBEDTLS_SSL_DEBUG_MSG(2, ("got an alert message, type: [%u:%u]",
4793 ssl->in_msg[0], ssl->in_msg[1]));
4794
4795 /*
4796 * Ignore non-fatal alerts, except close_notify and no_renegotiation
4797 */
4798 if (ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_FATAL) {
4799 MBEDTLS_SSL_DEBUG_MSG(1, ("is a fatal alert message (msg %d)",
4800 ssl->in_msg[1]));
4801 return MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE;
4802 }
4803
4804 if (ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
4805 ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY) {
4806 MBEDTLS_SSL_DEBUG_MSG(2, ("is a close notify message"));
4807 return MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY;
4808 }
4809
4810 #if defined(MBEDTLS_SSL_RENEGOTIATION_ENABLED)
4811 if (ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
4812 ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION) {
4813 MBEDTLS_SSL_DEBUG_MSG(2, ("is a no renegotiation alert"));
4814 /* Will be handled when trying to parse ServerHello */
4815 return 0;
4816 }
4817 #endif
4818 /* Silently ignore: fetch new message */
4819 return MBEDTLS_ERR_SSL_NON_FATAL;
4820 }
4821
4822 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4823 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
4824 /* Drop unexpected ApplicationData records,
4825 * except at the beginning of renegotiations */
4826 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA &&
4827 mbedtls_ssl_is_handshake_over(ssl) == 0
4828 #if defined(MBEDTLS_SSL_RENEGOTIATION)
4829 && !(ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
4830 ssl->state == MBEDTLS_SSL_SERVER_HELLO)
4831 #endif
4832 ) {
4833 MBEDTLS_SSL_DEBUG_MSG(1, ("dropping unexpected ApplicationData"));
4834 return MBEDTLS_ERR_SSL_NON_FATAL;
4835 }
4836
4837 if (ssl->handshake != NULL &&
4838 mbedtls_ssl_is_handshake_over(ssl) == 1) {
4839 mbedtls_ssl_handshake_wrapup_free_hs_transform(ssl);
4840 }
4841 }
4842 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4843
4844 return 0;
4845 }
4846
mbedtls_ssl_send_fatal_handshake_failure(mbedtls_ssl_context * ssl)4847 int mbedtls_ssl_send_fatal_handshake_failure(mbedtls_ssl_context *ssl)
4848 {
4849 return mbedtls_ssl_send_alert_message(ssl,
4850 MBEDTLS_SSL_ALERT_LEVEL_FATAL,
4851 MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE);
4852 }
4853
mbedtls_ssl_send_alert_message(mbedtls_ssl_context * ssl,unsigned char level,unsigned char message)4854 int mbedtls_ssl_send_alert_message(mbedtls_ssl_context *ssl,
4855 unsigned char level,
4856 unsigned char message)
4857 {
4858 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
4859
4860 if (ssl == NULL || ssl->conf == NULL) {
4861 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
4862 }
4863
4864 if (ssl->out_left != 0) {
4865 return mbedtls_ssl_flush_output(ssl);
4866 }
4867
4868 MBEDTLS_SSL_DEBUG_MSG(2, ("=> send alert message"));
4869 MBEDTLS_SSL_DEBUG_MSG(3, ("send alert level=%u message=%u", level, message));
4870
4871 ssl->out_msgtype = MBEDTLS_SSL_MSG_ALERT;
4872 ssl->out_msglen = 2;
4873 ssl->out_msg[0] = level;
4874 ssl->out_msg[1] = message;
4875
4876 if ((ret = mbedtls_ssl_write_record(ssl, SSL_FORCE_FLUSH)) != 0) {
4877 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_record", ret);
4878 return ret;
4879 }
4880 MBEDTLS_SSL_DEBUG_MSG(2, ("<= send alert message"));
4881
4882 return 0;
4883 }
4884
mbedtls_ssl_write_change_cipher_spec(mbedtls_ssl_context * ssl)4885 int mbedtls_ssl_write_change_cipher_spec(mbedtls_ssl_context *ssl)
4886 {
4887 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
4888
4889 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write change cipher spec"));
4890
4891 ssl->out_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC;
4892 ssl->out_msglen = 1;
4893 ssl->out_msg[0] = 1;
4894
4895 ssl->state++;
4896
4897 if ((ret = mbedtls_ssl_write_handshake_msg(ssl)) != 0) {
4898 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_handshake_msg", ret);
4899 return ret;
4900 }
4901
4902 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write change cipher spec"));
4903
4904 return 0;
4905 }
4906
mbedtls_ssl_parse_change_cipher_spec(mbedtls_ssl_context * ssl)4907 int mbedtls_ssl_parse_change_cipher_spec(mbedtls_ssl_context *ssl)
4908 {
4909 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
4910
4911 MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse change cipher spec"));
4912
4913 if ((ret = mbedtls_ssl_read_record(ssl, 1)) != 0) {
4914 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret);
4915 return ret;
4916 }
4917
4918 if (ssl->in_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) {
4919 MBEDTLS_SSL_DEBUG_MSG(1, ("bad change cipher spec message"));
4920 mbedtls_ssl_send_alert_message(ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
4921 MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE);
4922 return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
4923 }
4924
4925 /* CCS records are only accepted if they have length 1 and content '1',
4926 * so we don't need to check this here. */
4927
4928 /*
4929 * Switch to our negotiated transform and session parameters for inbound
4930 * data.
4931 */
4932 MBEDTLS_SSL_DEBUG_MSG(3, ("switching to new transform spec for inbound data"));
4933 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
4934 ssl->transform_in = ssl->transform_negotiate;
4935 #endif
4936 ssl->session_in = ssl->session_negotiate;
4937
4938 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4939 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
4940 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
4941 mbedtls_ssl_dtls_replay_reset(ssl);
4942 #endif
4943
4944 /* Increment epoch */
4945 if (++ssl->in_epoch == 0) {
4946 MBEDTLS_SSL_DEBUG_MSG(1, ("DTLS epoch would wrap"));
4947 /* This is highly unlikely to happen for legitimate reasons, so
4948 treat it as an attack and don't send an alert. */
4949 return MBEDTLS_ERR_SSL_COUNTER_WRAPPING;
4950 }
4951 } else
4952 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4953 memset(ssl->in_ctr, 0, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN);
4954
4955 mbedtls_ssl_update_in_pointers(ssl);
4956
4957 ssl->state++;
4958
4959 MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse change cipher spec"));
4960
4961 return 0;
4962 }
4963
4964 /* Once ssl->out_hdr as the address of the beginning of the
4965 * next outgoing record is set, deduce the other pointers.
4966 *
4967 * Note: For TLS, we save the implicit record sequence number
4968 * (entering MAC computation) in the 8 bytes before ssl->out_hdr,
4969 * and the caller has to make sure there's space for this.
4970 */
4971
ssl_transform_get_explicit_iv_len(mbedtls_ssl_transform const * transform)4972 static size_t ssl_transform_get_explicit_iv_len(
4973 mbedtls_ssl_transform const *transform)
4974 {
4975 return transform->ivlen - transform->fixed_ivlen;
4976 }
4977
mbedtls_ssl_update_out_pointers(mbedtls_ssl_context * ssl,mbedtls_ssl_transform * transform)4978 void mbedtls_ssl_update_out_pointers(mbedtls_ssl_context *ssl,
4979 mbedtls_ssl_transform *transform)
4980 {
4981 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4982 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
4983 ssl->out_ctr = ssl->out_hdr + 3;
4984 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
4985 ssl->out_cid = ssl->out_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
4986 ssl->out_len = ssl->out_cid;
4987 if (transform != NULL) {
4988 ssl->out_len += transform->out_cid_len;
4989 }
4990 #else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
4991 ssl->out_len = ssl->out_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
4992 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
4993 ssl->out_iv = ssl->out_len + 2;
4994 } else
4995 #endif
4996 {
4997 ssl->out_len = ssl->out_hdr + 3;
4998 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
4999 ssl->out_cid = ssl->out_len;
5000 #endif
5001 ssl->out_iv = ssl->out_hdr + 5;
5002 }
5003
5004 ssl->out_msg = ssl->out_iv;
5005 /* Adjust out_msg to make space for explicit IV, if used. */
5006 if (transform != NULL) {
5007 ssl->out_msg += ssl_transform_get_explicit_iv_len(transform);
5008 }
5009 }
5010
5011 /* Once ssl->in_hdr as the address of the beginning of the
5012 * next incoming record is set, deduce the other pointers.
5013 *
5014 * Note: For TLS, we save the implicit record sequence number
5015 * (entering MAC computation) in the 8 bytes before ssl->in_hdr,
5016 * and the caller has to make sure there's space for this.
5017 */
5018
mbedtls_ssl_update_in_pointers(mbedtls_ssl_context * ssl)5019 void mbedtls_ssl_update_in_pointers(mbedtls_ssl_context *ssl)
5020 {
5021 /* This function sets the pointers to match the case
5022 * of unprotected TLS/DTLS records, with both ssl->in_iv
5023 * and ssl->in_msg pointing to the beginning of the record
5024 * content.
5025 *
5026 * When decrypting a protected record, ssl->in_msg
5027 * will be shifted to point to the beginning of the
5028 * record plaintext.
5029 */
5030
5031 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5032 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
5033 /* This sets the header pointers to match records
5034 * without CID. When we receive a record containing
5035 * a CID, the fields are shifted accordingly in
5036 * ssl_parse_record_header(). */
5037 ssl->in_ctr = ssl->in_hdr + 3;
5038 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
5039 ssl->in_cid = ssl->in_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
5040 ssl->in_len = ssl->in_cid; /* Default: no CID */
5041 #else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
5042 ssl->in_len = ssl->in_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
5043 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
5044 ssl->in_iv = ssl->in_len + 2;
5045 } else
5046 #endif
5047 {
5048 ssl->in_ctr = ssl->in_hdr - MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
5049 ssl->in_len = ssl->in_hdr + 3;
5050 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
5051 ssl->in_cid = ssl->in_len;
5052 #endif
5053 ssl->in_iv = ssl->in_hdr + 5;
5054 }
5055
5056 /* This will be adjusted at record decryption time. */
5057 ssl->in_msg = ssl->in_iv;
5058 }
5059
5060 /*
5061 * Setup an SSL context
5062 */
5063
mbedtls_ssl_reset_in_out_pointers(mbedtls_ssl_context * ssl)5064 void mbedtls_ssl_reset_in_out_pointers(mbedtls_ssl_context *ssl)
5065 {
5066 /* Set the incoming and outgoing record pointers. */
5067 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5068 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
5069 ssl->out_hdr = ssl->out_buf;
5070 ssl->in_hdr = ssl->in_buf;
5071 } else
5072 #endif /* MBEDTLS_SSL_PROTO_DTLS */
5073 {
5074 ssl->out_ctr = ssl->out_buf;
5075 ssl->out_hdr = ssl->out_buf + 8;
5076 ssl->in_hdr = ssl->in_buf + 8;
5077 }
5078
5079 /* Derive other internal pointers. */
5080 mbedtls_ssl_update_out_pointers(ssl, NULL /* no transform enabled */);
5081 mbedtls_ssl_update_in_pointers(ssl);
5082 }
5083
5084 /*
5085 * SSL get accessors
5086 */
mbedtls_ssl_get_bytes_avail(const mbedtls_ssl_context * ssl)5087 size_t mbedtls_ssl_get_bytes_avail(const mbedtls_ssl_context *ssl)
5088 {
5089 return ssl->in_offt == NULL ? 0 : ssl->in_msglen;
5090 }
5091
mbedtls_ssl_check_pending(const mbedtls_ssl_context * ssl)5092 int mbedtls_ssl_check_pending(const mbedtls_ssl_context *ssl)
5093 {
5094 /*
5095 * Case A: We're currently holding back
5096 * a message for further processing.
5097 */
5098
5099 if (ssl->keep_current_message == 1) {
5100 MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: record held back for processing"));
5101 return 1;
5102 }
5103
5104 /*
5105 * Case B: Further records are pending in the current datagram.
5106 */
5107
5108 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5109 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
5110 ssl->in_left > ssl->next_record_offset) {
5111 MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: more records within current datagram"));
5112 return 1;
5113 }
5114 #endif /* MBEDTLS_SSL_PROTO_DTLS */
5115
5116 /*
5117 * Case C: A handshake message is being processed.
5118 */
5119
5120 if (ssl->in_hslen > 0 && ssl->in_hslen < ssl->in_msglen) {
5121 MBEDTLS_SSL_DEBUG_MSG(3,
5122 ("ssl_check_pending: more handshake messages within current record"));
5123 return 1;
5124 }
5125
5126 /*
5127 * Case D: An application data message is being processed
5128 */
5129 if (ssl->in_offt != NULL) {
5130 MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: application data record is being processed"));
5131 return 1;
5132 }
5133
5134 /*
5135 * In all other cases, the rest of the message can be dropped.
5136 * As in ssl_get_next_record, this needs to be adapted if
5137 * we implement support for multiple alerts in single records.
5138 */
5139
5140 MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: nothing pending"));
5141 return 0;
5142 }
5143
5144
mbedtls_ssl_get_record_expansion(const mbedtls_ssl_context * ssl)5145 int mbedtls_ssl_get_record_expansion(const mbedtls_ssl_context *ssl)
5146 {
5147 size_t transform_expansion = 0;
5148 const mbedtls_ssl_transform *transform = ssl->transform_out;
5149 unsigned block_size;
5150 #if defined(MBEDTLS_USE_PSA_CRYPTO)
5151 psa_key_attributes_t attr = PSA_KEY_ATTRIBUTES_INIT;
5152 psa_key_type_t key_type;
5153 #endif /* MBEDTLS_USE_PSA_CRYPTO */
5154
5155 size_t out_hdr_len = mbedtls_ssl_out_hdr_len(ssl);
5156
5157 if (transform == NULL) {
5158 return (int) out_hdr_len;
5159 }
5160
5161
5162 #if defined(MBEDTLS_USE_PSA_CRYPTO)
5163 if (transform->psa_alg == PSA_ALG_GCM ||
5164 transform->psa_alg == PSA_ALG_CCM ||
5165 transform->psa_alg == PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, 8) ||
5166 transform->psa_alg == PSA_ALG_CHACHA20_POLY1305 ||
5167 transform->psa_alg == MBEDTLS_SSL_NULL_CIPHER) {
5168 transform_expansion = transform->minlen;
5169 } else if (transform->psa_alg == PSA_ALG_CBC_NO_PADDING) {
5170 (void) psa_get_key_attributes(transform->psa_key_enc, &attr);
5171 key_type = psa_get_key_type(&attr);
5172
5173 block_size = PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type);
5174
5175 /* Expansion due to the addition of the MAC. */
5176 transform_expansion += transform->maclen;
5177
5178 /* Expansion due to the addition of CBC padding;
5179 * Theoretically up to 256 bytes, but we never use
5180 * more than the block size of the underlying cipher. */
5181 transform_expansion += block_size;
5182
5183 /* For TLS 1.2 or higher, an explicit IV is added
5184 * after the record header. */
5185 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
5186 transform_expansion += block_size;
5187 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
5188 } else {
5189 MBEDTLS_SSL_DEBUG_MSG(1,
5190 ("Unsupported psa_alg spotted in mbedtls_ssl_get_record_expansion()"));
5191 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
5192 }
5193 #else
5194 switch (mbedtls_cipher_get_cipher_mode(&transform->cipher_ctx_enc)) {
5195 case MBEDTLS_MODE_GCM:
5196 case MBEDTLS_MODE_CCM:
5197 case MBEDTLS_MODE_CHACHAPOLY:
5198 case MBEDTLS_MODE_STREAM:
5199 transform_expansion = transform->minlen;
5200 break;
5201
5202 case MBEDTLS_MODE_CBC:
5203
5204 block_size = mbedtls_cipher_get_block_size(
5205 &transform->cipher_ctx_enc);
5206
5207 /* Expansion due to the addition of the MAC. */
5208 transform_expansion += transform->maclen;
5209
5210 /* Expansion due to the addition of CBC padding;
5211 * Theoretically up to 256 bytes, but we never use
5212 * more than the block size of the underlying cipher. */
5213 transform_expansion += block_size;
5214
5215 /* For TLS 1.2 or higher, an explicit IV is added
5216 * after the record header. */
5217 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
5218 transform_expansion += block_size;
5219 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
5220
5221 break;
5222
5223 default:
5224 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
5225 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
5226 }
5227 #endif /* MBEDTLS_USE_PSA_CRYPTO */
5228
5229 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
5230 if (transform->out_cid_len != 0) {
5231 transform_expansion += MBEDTLS_SSL_MAX_CID_EXPANSION;
5232 }
5233 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
5234
5235 return (int) (out_hdr_len + transform_expansion);
5236 }
5237
5238 #if defined(MBEDTLS_SSL_RENEGOTIATION)
5239 /*
5240 * Check record counters and renegotiate if they're above the limit.
5241 */
5242 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_check_ctr_renegotiate(mbedtls_ssl_context * ssl)5243 static int ssl_check_ctr_renegotiate(mbedtls_ssl_context *ssl)
5244 {
5245 size_t ep_len = mbedtls_ssl_ep_len(ssl);
5246 int in_ctr_cmp;
5247 int out_ctr_cmp;
5248
5249 if (mbedtls_ssl_is_handshake_over(ssl) == 0 ||
5250 ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING ||
5251 ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED) {
5252 return 0;
5253 }
5254
5255 in_ctr_cmp = memcmp(ssl->in_ctr + ep_len,
5256 &ssl->conf->renego_period[ep_len],
5257 MBEDTLS_SSL_SEQUENCE_NUMBER_LEN - ep_len);
5258 out_ctr_cmp = memcmp(&ssl->cur_out_ctr[ep_len],
5259 &ssl->conf->renego_period[ep_len],
5260 sizeof(ssl->cur_out_ctr) - ep_len);
5261
5262 if (in_ctr_cmp <= 0 && out_ctr_cmp <= 0) {
5263 return 0;
5264 }
5265
5266 MBEDTLS_SSL_DEBUG_MSG(1, ("record counter limit reached: renegotiate"));
5267 return mbedtls_ssl_renegotiate(ssl);
5268 }
5269 #endif /* MBEDTLS_SSL_RENEGOTIATION */
5270
5271 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
5272
5273 #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
5274 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_tls13_check_new_session_ticket(mbedtls_ssl_context * ssl)5275 static int ssl_tls13_check_new_session_ticket(mbedtls_ssl_context *ssl)
5276 {
5277
5278 if ((ssl->in_hslen == mbedtls_ssl_hs_hdr_len(ssl)) ||
5279 (ssl->in_msg[0] != MBEDTLS_SSL_HS_NEW_SESSION_TICKET)) {
5280 return 0;
5281 }
5282
5283 ssl->keep_current_message = 1;
5284
5285 MBEDTLS_SSL_DEBUG_MSG(3, ("NewSessionTicket received"));
5286 mbedtls_ssl_handshake_set_state(ssl,
5287 MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET);
5288
5289 return MBEDTLS_ERR_SSL_WANT_READ;
5290 }
5291 #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
5292
5293 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_tls13_handle_hs_message_post_handshake(mbedtls_ssl_context * ssl)5294 static int ssl_tls13_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl)
5295 {
5296
5297 MBEDTLS_SSL_DEBUG_MSG(3, ("received post-handshake message"));
5298
5299 #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
5300 if (ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT) {
5301 int ret = ssl_tls13_check_new_session_ticket(ssl);
5302 if (ret != 0) {
5303 return ret;
5304 }
5305 }
5306 #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
5307
5308 /* Fail in all other cases. */
5309 return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
5310 }
5311 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
5312
5313 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
5314 /* This function is called from mbedtls_ssl_read() when a handshake message is
5315 * received after the initial handshake. In this context, handshake messages
5316 * may only be sent for the purpose of initiating renegotiations.
5317 *
5318 * This function is introduced as a separate helper since the handling
5319 * of post-handshake handshake messages changes significantly in TLS 1.3,
5320 * and having a helper function allows to distinguish between TLS <= 1.2 and
5321 * TLS 1.3 in the future without bloating the logic of mbedtls_ssl_read().
5322 */
5323 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_tls12_handle_hs_message_post_handshake(mbedtls_ssl_context * ssl)5324 static int ssl_tls12_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl)
5325 {
5326 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
5327
5328 /*
5329 * - For client-side, expect SERVER_HELLO_REQUEST.
5330 * - For server-side, expect CLIENT_HELLO.
5331 * - Fail (TLS) or silently drop record (DTLS) in other cases.
5332 */
5333
5334 #if defined(MBEDTLS_SSL_CLI_C)
5335 if (ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
5336 (ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_REQUEST ||
5337 ssl->in_hslen != mbedtls_ssl_hs_hdr_len(ssl))) {
5338 MBEDTLS_SSL_DEBUG_MSG(1, ("handshake received (not HelloRequest)"));
5339
5340 /* With DTLS, drop the packet (probably from last handshake) */
5341 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5342 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
5343 return 0;
5344 }
5345 #endif
5346 return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
5347 }
5348 #endif /* MBEDTLS_SSL_CLI_C */
5349
5350 #if defined(MBEDTLS_SSL_SRV_C)
5351 if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
5352 ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO) {
5353 MBEDTLS_SSL_DEBUG_MSG(1, ("handshake received (not ClientHello)"));
5354
5355 /* With DTLS, drop the packet (probably from last handshake) */
5356 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5357 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
5358 return 0;
5359 }
5360 #endif
5361 return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
5362 }
5363 #endif /* MBEDTLS_SSL_SRV_C */
5364
5365 #if defined(MBEDTLS_SSL_RENEGOTIATION)
5366 /* Determine whether renegotiation attempt should be accepted */
5367 if (!(ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED ||
5368 (ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION &&
5369 ssl->conf->allow_legacy_renegotiation ==
5370 MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION))) {
5371 /*
5372 * Accept renegotiation request
5373 */
5374
5375 /* DTLS clients need to know renego is server-initiated */
5376 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5377 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
5378 ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT) {
5379 ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_PENDING;
5380 }
5381 #endif
5382 ret = mbedtls_ssl_start_renegotiation(ssl);
5383 if (ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
5384 ret != 0) {
5385 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_start_renegotiation",
5386 ret);
5387 return ret;
5388 }
5389 } else
5390 #endif /* MBEDTLS_SSL_RENEGOTIATION */
5391 {
5392 /*
5393 * Refuse renegotiation
5394 */
5395
5396 MBEDTLS_SSL_DEBUG_MSG(3, ("refusing renegotiation, sending alert"));
5397
5398 if ((ret = mbedtls_ssl_send_alert_message(ssl,
5399 MBEDTLS_SSL_ALERT_LEVEL_WARNING,
5400 MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION)) != 0) {
5401 return ret;
5402 }
5403 }
5404
5405 return 0;
5406 }
5407 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
5408
5409 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_handle_hs_message_post_handshake(mbedtls_ssl_context * ssl)5410 static int ssl_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl)
5411 {
5412 /* Check protocol version and dispatch accordingly. */
5413 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
5414 if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
5415 return ssl_tls13_handle_hs_message_post_handshake(ssl);
5416 }
5417 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
5418
5419 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
5420 if (ssl->tls_version <= MBEDTLS_SSL_VERSION_TLS1_2) {
5421 return ssl_tls12_handle_hs_message_post_handshake(ssl);
5422 }
5423 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
5424
5425 /* Should never happen */
5426 return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
5427 }
5428
5429 /*
5430 * Receive application data decrypted from the SSL layer
5431 */
mbedtls_ssl_read(mbedtls_ssl_context * ssl,unsigned char * buf,size_t len)5432 int mbedtls_ssl_read(mbedtls_ssl_context *ssl, unsigned char *buf, size_t len)
5433 {
5434 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
5435 size_t n;
5436
5437 if (ssl == NULL || ssl->conf == NULL) {
5438 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
5439 }
5440
5441 MBEDTLS_SSL_DEBUG_MSG(2, ("=> read"));
5442
5443 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5444 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
5445 if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) {
5446 return ret;
5447 }
5448
5449 if (ssl->handshake != NULL &&
5450 ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING) {
5451 if ((ret = mbedtls_ssl_flight_transmit(ssl)) != 0) {
5452 return ret;
5453 }
5454 }
5455 }
5456 #endif
5457
5458 /*
5459 * Check if renegotiation is necessary and/or handshake is
5460 * in process. If yes, perform/continue, and fall through
5461 * if an unexpected packet is received while the client
5462 * is waiting for the ServerHello.
5463 *
5464 * (There is no equivalent to the last condition on
5465 * the server-side as it is not treated as within
5466 * a handshake while waiting for the ClientHello
5467 * after a renegotiation request.)
5468 */
5469
5470 #if defined(MBEDTLS_SSL_RENEGOTIATION)
5471 ret = ssl_check_ctr_renegotiate(ssl);
5472 if (ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
5473 ret != 0) {
5474 MBEDTLS_SSL_DEBUG_RET(1, "ssl_check_ctr_renegotiate", ret);
5475 return ret;
5476 }
5477 #endif
5478
5479 if (ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER) {
5480 ret = mbedtls_ssl_handshake(ssl);
5481 if (ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
5482 ret != 0) {
5483 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake", ret);
5484 return ret;
5485 }
5486 }
5487
5488 /* Loop as long as no application data record is available */
5489 while (ssl->in_offt == NULL) {
5490 /* Start timer if not already running */
5491 if (ssl->f_get_timer != NULL &&
5492 ssl->f_get_timer(ssl->p_timer) == -1) {
5493 mbedtls_ssl_set_timer(ssl, ssl->conf->read_timeout);
5494 }
5495
5496 if ((ret = mbedtls_ssl_read_record(ssl, 1)) != 0) {
5497 if (ret == MBEDTLS_ERR_SSL_CONN_EOF) {
5498 return 0;
5499 }
5500
5501 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret);
5502 return ret;
5503 }
5504
5505 if (ssl->in_msglen == 0 &&
5506 ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA) {
5507 /*
5508 * OpenSSL sends empty messages to randomize the IV
5509 */
5510 if ((ret = mbedtls_ssl_read_record(ssl, 1)) != 0) {
5511 if (ret == MBEDTLS_ERR_SSL_CONN_EOF) {
5512 return 0;
5513 }
5514
5515 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret);
5516 return ret;
5517 }
5518 }
5519
5520 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE) {
5521 ret = ssl_handle_hs_message_post_handshake(ssl);
5522 if (ret != 0) {
5523 MBEDTLS_SSL_DEBUG_RET(1, "ssl_handle_hs_message_post_handshake",
5524 ret);
5525 return ret;
5526 }
5527
5528 /* At this point, we don't know whether the renegotiation triggered
5529 * by the post-handshake message has been completed or not. The cases
5530 * to consider are the following:
5531 * 1) The renegotiation is complete. In this case, no new record
5532 * has been read yet.
5533 * 2) The renegotiation is incomplete because the client received
5534 * an application data record while awaiting the ServerHello.
5535 * 3) The renegotiation is incomplete because the client received
5536 * a non-handshake, non-application data message while awaiting
5537 * the ServerHello.
5538 *
5539 * In each of these cases, looping will be the proper action:
5540 * - For 1), the next iteration will read a new record and check
5541 * if it's application data.
5542 * - For 2), the loop condition isn't satisfied as application data
5543 * is present, hence continue is the same as break
5544 * - For 3), the loop condition is satisfied and read_record
5545 * will re-deliver the message that was held back by the client
5546 * when expecting the ServerHello.
5547 */
5548
5549 continue;
5550 }
5551 #if defined(MBEDTLS_SSL_RENEGOTIATION)
5552 else if (ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING) {
5553 if (ssl->conf->renego_max_records >= 0) {
5554 if (++ssl->renego_records_seen > ssl->conf->renego_max_records) {
5555 MBEDTLS_SSL_DEBUG_MSG(1, ("renegotiation requested, "
5556 "but not honored by client"));
5557 return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
5558 }
5559 }
5560 }
5561 #endif /* MBEDTLS_SSL_RENEGOTIATION */
5562
5563 /* Fatal and closure alerts handled by mbedtls_ssl_read_record() */
5564 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT) {
5565 MBEDTLS_SSL_DEBUG_MSG(2, ("ignoring non-fatal non-closure alert"));
5566 return MBEDTLS_ERR_SSL_WANT_READ;
5567 }
5568
5569 if (ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA) {
5570 MBEDTLS_SSL_DEBUG_MSG(1, ("bad application data message"));
5571 return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
5572 }
5573
5574 ssl->in_offt = ssl->in_msg;
5575
5576 /* We're going to return something now, cancel timer,
5577 * except if handshake (renegotiation) is in progress */
5578 if (mbedtls_ssl_is_handshake_over(ssl) == 1) {
5579 mbedtls_ssl_set_timer(ssl, 0);
5580 }
5581
5582 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5583 /* If we requested renego but received AppData, resend HelloRequest.
5584 * Do it now, after setting in_offt, to avoid taking this branch
5585 * again if ssl_write_hello_request() returns WANT_WRITE */
5586 #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
5587 if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
5588 ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING) {
5589 if ((ret = mbedtls_ssl_resend_hello_request(ssl)) != 0) {
5590 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend_hello_request",
5591 ret);
5592 return ret;
5593 }
5594 }
5595 #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
5596 #endif /* MBEDTLS_SSL_PROTO_DTLS */
5597 }
5598
5599 n = (len < ssl->in_msglen)
5600 ? len : ssl->in_msglen;
5601
5602 if (len != 0) {
5603 memcpy(buf, ssl->in_offt, n);
5604 ssl->in_msglen -= n;
5605 }
5606
5607 /* Zeroising the plaintext buffer to erase unused application data
5608 from the memory. */
5609 mbedtls_platform_zeroize(ssl->in_offt, n);
5610
5611 if (ssl->in_msglen == 0) {
5612 /* all bytes consumed */
5613 ssl->in_offt = NULL;
5614 ssl->keep_current_message = 0;
5615 } else {
5616 /* more data available */
5617 ssl->in_offt += n;
5618 }
5619
5620 MBEDTLS_SSL_DEBUG_MSG(2, ("<= read"));
5621
5622 return (int) n;
5623 }
5624
5625 /*
5626 * Send application data to be encrypted by the SSL layer, taking care of max
5627 * fragment length and buffer size.
5628 *
5629 * According to RFC 5246 Section 6.2.1:
5630 *
5631 * Zero-length fragments of Application data MAY be sent as they are
5632 * potentially useful as a traffic analysis countermeasure.
5633 *
5634 * Therefore, it is possible that the input message length is 0 and the
5635 * corresponding return code is 0 on success.
5636 */
5637 MBEDTLS_CHECK_RETURN_CRITICAL
ssl_write_real(mbedtls_ssl_context * ssl,const unsigned char * buf,size_t len)5638 static int ssl_write_real(mbedtls_ssl_context *ssl,
5639 const unsigned char *buf, size_t len)
5640 {
5641 int ret = mbedtls_ssl_get_max_out_record_payload(ssl);
5642 const size_t max_len = (size_t) ret;
5643
5644 if (ret < 0) {
5645 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_get_max_out_record_payload", ret);
5646 return ret;
5647 }
5648
5649 if (len > max_len) {
5650 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5651 if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
5652 MBEDTLS_SSL_DEBUG_MSG(1, ("fragment larger than the (negotiated) "
5653 "maximum fragment length: %" MBEDTLS_PRINTF_SIZET
5654 " > %" MBEDTLS_PRINTF_SIZET,
5655 len, max_len));
5656 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
5657 } else
5658 #endif
5659 len = max_len;
5660 }
5661
5662 if (ssl->out_left != 0) {
5663 /*
5664 * The user has previously tried to send the data and
5665 * MBEDTLS_ERR_SSL_WANT_WRITE or the message was only partially
5666 * written. In this case, we expect the high-level write function
5667 * (e.g. mbedtls_ssl_write()) to be called with the same parameters
5668 */
5669 if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) {
5670 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_flush_output", ret);
5671 return ret;
5672 }
5673 } else {
5674 /*
5675 * The user is trying to send a message the first time, so we need to
5676 * copy the data into the internal buffers and setup the data structure
5677 * to keep track of partial writes
5678 */
5679 ssl->out_msglen = len;
5680 ssl->out_msgtype = MBEDTLS_SSL_MSG_APPLICATION_DATA;
5681 if (len > 0) {
5682 memcpy(ssl->out_msg, buf, len);
5683 }
5684
5685 if ((ret = mbedtls_ssl_write_record(ssl, SSL_FORCE_FLUSH)) != 0) {
5686 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_record", ret);
5687 return ret;
5688 }
5689 }
5690
5691 return (int) len;
5692 }
5693
5694 /*
5695 * Write application data (public-facing wrapper)
5696 */
mbedtls_ssl_write(mbedtls_ssl_context * ssl,const unsigned char * buf,size_t len)5697 int mbedtls_ssl_write(mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len)
5698 {
5699 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
5700
5701 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write"));
5702
5703 if (ssl == NULL || ssl->conf == NULL) {
5704 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
5705 }
5706
5707 #if defined(MBEDTLS_SSL_RENEGOTIATION)
5708 if ((ret = ssl_check_ctr_renegotiate(ssl)) != 0) {
5709 MBEDTLS_SSL_DEBUG_RET(1, "ssl_check_ctr_renegotiate", ret);
5710 return ret;
5711 }
5712 #endif
5713
5714 if (ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER) {
5715 if ((ret = mbedtls_ssl_handshake(ssl)) != 0) {
5716 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake", ret);
5717 return ret;
5718 }
5719 }
5720
5721 ret = ssl_write_real(ssl, buf, len);
5722
5723 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write"));
5724
5725 return ret;
5726 }
5727
5728 /*
5729 * Notify the peer that the connection is being closed
5730 */
mbedtls_ssl_close_notify(mbedtls_ssl_context * ssl)5731 int mbedtls_ssl_close_notify(mbedtls_ssl_context *ssl)
5732 {
5733 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
5734
5735 if (ssl == NULL || ssl->conf == NULL) {
5736 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
5737 }
5738
5739 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write close notify"));
5740
5741 if (mbedtls_ssl_is_handshake_over(ssl) == 1) {
5742 if ((ret = mbedtls_ssl_send_alert_message(ssl,
5743 MBEDTLS_SSL_ALERT_LEVEL_WARNING,
5744 MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY)) != 0) {
5745 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_send_alert_message", ret);
5746 return ret;
5747 }
5748 }
5749
5750 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write close notify"));
5751
5752 return 0;
5753 }
5754
mbedtls_ssl_transform_free(mbedtls_ssl_transform * transform)5755 void mbedtls_ssl_transform_free(mbedtls_ssl_transform *transform)
5756 {
5757 if (transform == NULL) {
5758 return;
5759 }
5760
5761 #if defined(MBEDTLS_USE_PSA_CRYPTO)
5762 psa_destroy_key(transform->psa_key_enc);
5763 psa_destroy_key(transform->psa_key_dec);
5764 #else
5765 mbedtls_cipher_free(&transform->cipher_ctx_enc);
5766 mbedtls_cipher_free(&transform->cipher_ctx_dec);
5767 #endif /* MBEDTLS_USE_PSA_CRYPTO */
5768
5769 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
5770 #if defined(MBEDTLS_USE_PSA_CRYPTO)
5771 psa_destroy_key(transform->psa_mac_enc);
5772 psa_destroy_key(transform->psa_mac_dec);
5773 #else
5774 mbedtls_md_free(&transform->md_ctx_enc);
5775 mbedtls_md_free(&transform->md_ctx_dec);
5776 #endif /* MBEDTLS_USE_PSA_CRYPTO */
5777 #endif
5778
5779 mbedtls_platform_zeroize(transform, sizeof(mbedtls_ssl_transform));
5780 }
5781
mbedtls_ssl_set_inbound_transform(mbedtls_ssl_context * ssl,mbedtls_ssl_transform * transform)5782 void mbedtls_ssl_set_inbound_transform(mbedtls_ssl_context *ssl,
5783 mbedtls_ssl_transform *transform)
5784 {
5785 ssl->transform_in = transform;
5786 memset(ssl->in_ctr, 0, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN);
5787 }
5788
mbedtls_ssl_set_outbound_transform(mbedtls_ssl_context * ssl,mbedtls_ssl_transform * transform)5789 void mbedtls_ssl_set_outbound_transform(mbedtls_ssl_context *ssl,
5790 mbedtls_ssl_transform *transform)
5791 {
5792 ssl->transform_out = transform;
5793 memset(ssl->cur_out_ctr, 0, sizeof(ssl->cur_out_ctr));
5794 }
5795
5796 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5797
mbedtls_ssl_buffering_free(mbedtls_ssl_context * ssl)5798 void mbedtls_ssl_buffering_free(mbedtls_ssl_context *ssl)
5799 {
5800 unsigned offset;
5801 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
5802
5803 if (hs == NULL) {
5804 return;
5805 }
5806
5807 ssl_free_buffered_record(ssl);
5808
5809 for (offset = 0; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++) {
5810 ssl_buffering_free_slot(ssl, offset);
5811 }
5812 }
5813
ssl_buffering_free_slot(mbedtls_ssl_context * ssl,uint8_t slot)5814 static void ssl_buffering_free_slot(mbedtls_ssl_context *ssl,
5815 uint8_t slot)
5816 {
5817 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
5818 mbedtls_ssl_hs_buffer * const hs_buf = &hs->buffering.hs[slot];
5819
5820 if (slot >= MBEDTLS_SSL_MAX_BUFFERED_HS) {
5821 return;
5822 }
5823
5824 if (hs_buf->is_valid == 1) {
5825 hs->buffering.total_bytes_buffered -= hs_buf->data_len;
5826 mbedtls_platform_zeroize(hs_buf->data, hs_buf->data_len);
5827 mbedtls_free(hs_buf->data);
5828 memset(hs_buf, 0, sizeof(mbedtls_ssl_hs_buffer));
5829 }
5830 }
5831
5832 #endif /* MBEDTLS_SSL_PROTO_DTLS */
5833
5834 /*
5835 * Convert version numbers to/from wire format
5836 * and, for DTLS, to/from TLS equivalent.
5837 *
5838 * For TLS this is the identity.
5839 * For DTLS, map as follows, then use 1's complement (v -> ~v):
5840 * 1.x <-> 3.x+1 for x != 0 (DTLS 1.2 based on TLS 1.2)
5841 * DTLS 1.0 is stored as TLS 1.1 internally
5842 */
mbedtls_ssl_write_version(unsigned char version[2],int transport,mbedtls_ssl_protocol_version tls_version)5843 void mbedtls_ssl_write_version(unsigned char version[2], int transport,
5844 mbedtls_ssl_protocol_version tls_version)
5845 {
5846 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5847 if (transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
5848 tls_version =
5849 ~(tls_version - (tls_version == 0x0302 ? 0x0202 : 0x0201));
5850 }
5851 #else
5852 ((void) transport);
5853 #endif
5854 MBEDTLS_PUT_UINT16_BE(tls_version, version, 0);
5855 }
5856
mbedtls_ssl_read_version(const unsigned char version[2],int transport)5857 uint16_t mbedtls_ssl_read_version(const unsigned char version[2],
5858 int transport)
5859 {
5860 uint16_t tls_version = MBEDTLS_GET_UINT16_BE(version, 0);
5861 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5862 if (transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
5863 tls_version =
5864 ~(tls_version - (tls_version == 0xfeff ? 0x0202 : 0x0201));
5865 }
5866 #else
5867 ((void) transport);
5868 #endif
5869 return tls_version;
5870 }
5871
5872 /*
5873 * Send pending fatal alert.
5874 * 0, No alert message.
5875 * !0, if mbedtls_ssl_send_alert_message() returned in error, the error code it
5876 * returned, ssl->alert_reason otherwise.
5877 */
mbedtls_ssl_handle_pending_alert(mbedtls_ssl_context * ssl)5878 int mbedtls_ssl_handle_pending_alert(mbedtls_ssl_context *ssl)
5879 {
5880 int ret;
5881
5882 /* No pending alert, return success*/
5883 if (ssl->send_alert == 0) {
5884 return 0;
5885 }
5886
5887 ret = mbedtls_ssl_send_alert_message(ssl,
5888 MBEDTLS_SSL_ALERT_LEVEL_FATAL,
5889 ssl->alert_type);
5890
5891 /* If mbedtls_ssl_send_alert_message() returned with MBEDTLS_ERR_SSL_WANT_WRITE,
5892 * do not clear the alert to be able to send it later.
5893 */
5894 if (ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
5895 ssl->send_alert = 0;
5896 }
5897
5898 if (ret != 0) {
5899 return ret;
5900 }
5901
5902 return ssl->alert_reason;
5903 }
5904
5905 /*
5906 * Set pending fatal alert flag.
5907 */
mbedtls_ssl_pend_fatal_alert(mbedtls_ssl_context * ssl,unsigned char alert_type,int alert_reason)5908 void mbedtls_ssl_pend_fatal_alert(mbedtls_ssl_context *ssl,
5909 unsigned char alert_type,
5910 int alert_reason)
5911 {
5912 ssl->send_alert = 1;
5913 ssl->alert_type = alert_type;
5914 ssl->alert_reason = alert_reason;
5915 }
5916
5917 #endif /* MBEDTLS_SSL_TLS_C */
5918
