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 #if defined(MBEDTLS_PLATFORM_C)
30 #include "mbedtls/platform.h"
31 #else
32 #include <stdlib.h>
33 #define mbedtls_calloc calloc
34 #define mbedtls_free free
35 #endif
36
37 #include "mbedtls/ssl.h"
38 #include "ssl_misc.h"
39 #include "mbedtls/debug.h"
40 #include "mbedtls/error.h"
41 #include "mbedtls/platform_util.h"
42 #include "mbedtls/version.h"
43
44 #include "ssl_invasive.h"
45
46 #include <string.h>
47
48 #if defined(MBEDTLS_USE_PSA_CRYPTO)
49 #include "mbedtls/psa_util.h"
50 #include "psa/crypto.h"
51 #endif
52
53 #if defined(MBEDTLS_X509_CRT_PARSE_C)
54 #include "mbedtls/oid.h"
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 MBEDTLS_SSL_DEBUG_MSG( 3, ( "set_timer to %d ms", (int) millisecs ) );
69 ssl->f_set_timer( ssl->p_timer, millisecs / 4, millisecs );
70 }
71
72 /*
73 * Return -1 is timer is expired, 0 if it isn't.
74 */
mbedtls_ssl_check_timer(mbedtls_ssl_context * ssl)75 int mbedtls_ssl_check_timer( mbedtls_ssl_context *ssl )
76 {
77 if( ssl->f_get_timer == NULL )
78 return( 0 );
79
80 if( ssl->f_get_timer( ssl->p_timer ) == 2 )
81 {
82 MBEDTLS_SSL_DEBUG_MSG( 3, ( "timer expired" ) );
83 return( -1 );
84 }
85
86 return( 0 );
87 }
88
89 static int ssl_parse_record_header( mbedtls_ssl_context const *ssl,
90 unsigned char *buf,
91 size_t len,
92 mbedtls_record *rec );
93
mbedtls_ssl_check_record(mbedtls_ssl_context const * ssl,unsigned char * buf,size_t buflen)94 int mbedtls_ssl_check_record( mbedtls_ssl_context const *ssl,
95 unsigned char *buf,
96 size_t buflen )
97 {
98 int ret = 0;
99 MBEDTLS_SSL_DEBUG_MSG( 1, ( "=> mbedtls_ssl_check_record" ) );
100 MBEDTLS_SSL_DEBUG_BUF( 3, "record buffer", buf, buflen );
101
102 /* We don't support record checking in TLS because
103 * there doesn't seem to be a usecase for it.
104 */
105 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_STREAM )
106 {
107 ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
108 goto exit;
109 }
110 #if defined(MBEDTLS_SSL_PROTO_DTLS)
111 else
112 {
113 mbedtls_record rec;
114
115 ret = ssl_parse_record_header( ssl, buf, buflen, &rec );
116 if( ret != 0 )
117 {
118 MBEDTLS_SSL_DEBUG_RET( 3, "ssl_parse_record_header", ret );
119 goto exit;
120 }
121
122 if( ssl->transform_in != NULL )
123 {
124 ret = mbedtls_ssl_decrypt_buf( ssl, ssl->transform_in, &rec );
125 if( ret != 0 )
126 {
127 MBEDTLS_SSL_DEBUG_RET( 3, "mbedtls_ssl_decrypt_buf", ret );
128 goto exit;
129 }
130 }
131 }
132 #endif /* MBEDTLS_SSL_PROTO_DTLS */
133
134 exit:
135 /* On success, we have decrypted the buffer in-place, so make
136 * sure we don't leak any plaintext data. */
137 mbedtls_platform_zeroize( buf, buflen );
138
139 /* For the purpose of this API, treat messages with unexpected CID
140 * as well as such from future epochs as unexpected. */
141 if( ret == MBEDTLS_ERR_SSL_UNEXPECTED_CID ||
142 ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE )
143 {
144 ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD;
145 }
146
147 MBEDTLS_SSL_DEBUG_MSG( 1, ( "<= mbedtls_ssl_check_record" ) );
148 return( ret );
149 }
150
151 #define SSL_DONT_FORCE_FLUSH 0
152 #define SSL_FORCE_FLUSH 1
153
154 #if defined(MBEDTLS_SSL_PROTO_DTLS)
155
156 /* Forward declarations for functions related to message buffering. */
157 static void ssl_buffering_free_slot( mbedtls_ssl_context *ssl,
158 uint8_t slot );
159 static void ssl_free_buffered_record( mbedtls_ssl_context *ssl );
160 static int ssl_load_buffered_message( mbedtls_ssl_context *ssl );
161 static int ssl_load_buffered_record( mbedtls_ssl_context *ssl );
162 static int ssl_buffer_message( mbedtls_ssl_context *ssl );
163 static int ssl_buffer_future_record( mbedtls_ssl_context *ssl,
164 mbedtls_record const *rec );
165 static int ssl_next_record_is_in_datagram( mbedtls_ssl_context *ssl );
166
ssl_get_maximum_datagram_size(mbedtls_ssl_context const * ssl)167 static size_t ssl_get_maximum_datagram_size( mbedtls_ssl_context const *ssl )
168 {
169 size_t mtu = mbedtls_ssl_get_current_mtu( ssl );
170 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
171 size_t out_buf_len = ssl->out_buf_len;
172 #else
173 size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN;
174 #endif
175
176 if( mtu != 0 && mtu < out_buf_len )
177 return( mtu );
178
179 return( out_buf_len );
180 }
181
ssl_get_remaining_space_in_datagram(mbedtls_ssl_context const * ssl)182 static int ssl_get_remaining_space_in_datagram( mbedtls_ssl_context const *ssl )
183 {
184 size_t const bytes_written = ssl->out_left;
185 size_t const mtu = ssl_get_maximum_datagram_size( ssl );
186
187 /* Double-check that the write-index hasn't gone
188 * past what we can transmit in a single datagram. */
189 if( bytes_written > mtu )
190 {
191 /* Should never happen... */
192 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
193 }
194
195 return( (int) ( mtu - bytes_written ) );
196 }
197
ssl_get_remaining_payload_in_datagram(mbedtls_ssl_context const * ssl)198 static int ssl_get_remaining_payload_in_datagram( mbedtls_ssl_context const *ssl )
199 {
200 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
201 size_t remaining, expansion;
202 size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN;
203
204 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
205 const size_t mfl = mbedtls_ssl_get_output_max_frag_len( ssl );
206
207 if( max_len > mfl )
208 max_len = mfl;
209
210 /* By the standard (RFC 6066 Sect. 4), the MFL extension
211 * only limits the maximum record payload size, so in theory
212 * we would be allowed to pack multiple records of payload size
213 * MFL into a single datagram. However, this would mean that there's
214 * no way to explicitly communicate MTU restrictions to the peer.
215 *
216 * The following reduction of max_len makes sure that we never
217 * write datagrams larger than MFL + Record Expansion Overhead.
218 */
219 if( max_len <= ssl->out_left )
220 return( 0 );
221
222 max_len -= ssl->out_left;
223 #endif
224
225 ret = ssl_get_remaining_space_in_datagram( ssl );
226 if( ret < 0 )
227 return( ret );
228 remaining = (size_t) ret;
229
230 ret = mbedtls_ssl_get_record_expansion( ssl );
231 if( ret < 0 )
232 return( ret );
233 expansion = (size_t) ret;
234
235 if( remaining <= expansion )
236 return( 0 );
237
238 remaining -= expansion;
239 if( remaining >= max_len )
240 remaining = max_len;
241
242 return( (int) remaining );
243 }
244
245 /*
246 * Double the retransmit timeout value, within the allowed range,
247 * returning -1 if the maximum value has already been reached.
248 */
ssl_double_retransmit_timeout(mbedtls_ssl_context * ssl)249 static int ssl_double_retransmit_timeout( mbedtls_ssl_context *ssl )
250 {
251 uint32_t new_timeout;
252
253 if( ssl->handshake->retransmit_timeout >= ssl->conf->hs_timeout_max )
254 return( -1 );
255
256 /* Implement the final paragraph of RFC 6347 section 4.1.1.1
257 * in the following way: after the initial transmission and a first
258 * retransmission, back off to a temporary estimated MTU of 508 bytes.
259 * This value is guaranteed to be deliverable (if not guaranteed to be
260 * delivered) of any compliant IPv4 (and IPv6) network, and should work
261 * on most non-IP stacks too. */
262 if( ssl->handshake->retransmit_timeout != ssl->conf->hs_timeout_min )
263 {
264 ssl->handshake->mtu = 508;
265 MBEDTLS_SSL_DEBUG_MSG( 2, ( "mtu autoreduction to %d bytes", ssl->handshake->mtu ) );
266 }
267
268 new_timeout = 2 * ssl->handshake->retransmit_timeout;
269
270 /* Avoid arithmetic overflow and range overflow */
271 if( new_timeout < ssl->handshake->retransmit_timeout ||
272 new_timeout > ssl->conf->hs_timeout_max )
273 {
274 new_timeout = ssl->conf->hs_timeout_max;
275 }
276
277 ssl->handshake->retransmit_timeout = new_timeout;
278 MBEDTLS_SSL_DEBUG_MSG( 3, ( "update timeout value to %lu millisecs",
279 (unsigned long) ssl->handshake->retransmit_timeout ) );
280
281 return( 0 );
282 }
283
ssl_reset_retransmit_timeout(mbedtls_ssl_context * ssl)284 static void ssl_reset_retransmit_timeout( mbedtls_ssl_context *ssl )
285 {
286 ssl->handshake->retransmit_timeout = ssl->conf->hs_timeout_min;
287 MBEDTLS_SSL_DEBUG_MSG( 3, ( "update timeout value to %lu millisecs",
288 (unsigned long) ssl->handshake->retransmit_timeout ) );
289 }
290 #endif /* MBEDTLS_SSL_PROTO_DTLS */
291
292 /*
293 * Encryption/decryption functions
294 */
295
296 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) || \
297 defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
298
ssl_compute_padding_length(size_t len,size_t granularity)299 static size_t ssl_compute_padding_length( size_t len,
300 size_t granularity )
301 {
302 return( ( granularity - ( len + 1 ) % granularity ) % granularity );
303 }
304
305 /* This functions transforms a (D)TLS plaintext fragment and a record content
306 * type into an instance of the (D)TLSInnerPlaintext structure. This is used
307 * in DTLS 1.2 + CID and within TLS 1.3 to allow flexible padding and to protect
308 * a record's content type.
309 *
310 * struct {
311 * opaque content[DTLSPlaintext.length];
312 * ContentType real_type;
313 * uint8 zeros[length_of_padding];
314 * } (D)TLSInnerPlaintext;
315 *
316 * Input:
317 * - `content`: The beginning of the buffer holding the
318 * plaintext to be wrapped.
319 * - `*content_size`: The length of the plaintext in Bytes.
320 * - `max_len`: The number of Bytes available starting from
321 * `content`. This must be `>= *content_size`.
322 * - `rec_type`: The desired record content type.
323 *
324 * Output:
325 * - `content`: The beginning of the resulting (D)TLSInnerPlaintext structure.
326 * - `*content_size`: The length of the resulting (D)TLSInnerPlaintext structure.
327 *
328 * Returns:
329 * - `0` on success.
330 * - A negative error code if `max_len` didn't offer enough space
331 * for the expansion.
332 */
ssl_build_inner_plaintext(unsigned char * content,size_t * content_size,size_t remaining,uint8_t rec_type,size_t pad)333 static int ssl_build_inner_plaintext( unsigned char *content,
334 size_t *content_size,
335 size_t remaining,
336 uint8_t rec_type,
337 size_t pad )
338 {
339 size_t len = *content_size;
340
341 /* Write real content type */
342 if( remaining == 0 )
343 return( -1 );
344 content[ len ] = rec_type;
345 len++;
346 remaining--;
347
348 if( remaining < pad )
349 return( -1 );
350 memset( content + len, 0, pad );
351 len += pad;
352 remaining -= pad;
353
354 *content_size = len;
355 return( 0 );
356 }
357
358 /* This function parses a (D)TLSInnerPlaintext structure.
359 * See ssl_build_inner_plaintext() for details. */
ssl_parse_inner_plaintext(unsigned char const * content,size_t * content_size,uint8_t * rec_type)360 static int ssl_parse_inner_plaintext( unsigned char const *content,
361 size_t *content_size,
362 uint8_t *rec_type )
363 {
364 size_t remaining = *content_size;
365
366 /* Determine length of padding by skipping zeroes from the back. */
367 do
368 {
369 if( remaining == 0 )
370 return( -1 );
371 remaining--;
372 } while( content[ remaining ] == 0 );
373
374 *content_size = remaining;
375 *rec_type = content[ remaining ];
376
377 return( 0 );
378 }
379 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID ||
380 MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
381
382 /* `add_data` must have size 13 Bytes if the CID extension is disabled,
383 * and 13 + 1 + CID-length Bytes if the CID extension is enabled. */
ssl_extract_add_data_from_record(unsigned char * add_data,size_t * add_data_len,mbedtls_record * rec,unsigned minor_ver,size_t taglen)384 static void ssl_extract_add_data_from_record( unsigned char* add_data,
385 size_t *add_data_len,
386 mbedtls_record *rec,
387 unsigned minor_ver,
388 size_t taglen )
389 {
390 /* Quoting RFC 5246 (TLS 1.2):
391 *
392 * additional_data = seq_num + TLSCompressed.type +
393 * TLSCompressed.version + TLSCompressed.length;
394 *
395 * For the CID extension, this is extended as follows
396 * (quoting draft-ietf-tls-dtls-connection-id-05,
397 * https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05):
398 *
399 * additional_data = seq_num + DTLSPlaintext.type +
400 * DTLSPlaintext.version +
401 * cid +
402 * cid_length +
403 * length_of_DTLSInnerPlaintext;
404 *
405 * For TLS 1.3, the record sequence number is dropped from the AAD
406 * and encoded within the nonce of the AEAD operation instead.
407 * Moreover, the additional data involves the length of the TLS
408 * ciphertext, not the TLS plaintext as in earlier versions.
409 * Quoting RFC 8446 (TLS 1.3):
410 *
411 * additional_data = TLSCiphertext.opaque_type ||
412 * TLSCiphertext.legacy_record_version ||
413 * TLSCiphertext.length
414 *
415 * We pass the tag length to this function in order to compute the
416 * ciphertext length from the inner plaintext length rec->data_len via
417 *
418 * TLSCiphertext.length = TLSInnerPlaintext.length + taglen.
419 *
420 */
421
422 unsigned char *cur = add_data;
423 size_t ad_len_field = rec->data_len;
424
425 #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
426 if( minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
427 {
428 /* In TLS 1.3, the AAD contains the length of the TLSCiphertext,
429 * which differs from the length of the TLSInnerPlaintext
430 * by the length of the authentication tag. */
431 ad_len_field += taglen;
432 }
433 else
434 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
435 {
436 ((void) minor_ver);
437 ((void) taglen);
438 memcpy( cur, rec->ctr, sizeof( rec->ctr ) );
439 cur += sizeof( rec->ctr );
440 }
441
442 *cur = rec->type;
443 cur++;
444
445 memcpy( cur, rec->ver, sizeof( rec->ver ) );
446 cur += sizeof( rec->ver );
447
448 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
449 if( rec->cid_len != 0 )
450 {
451 memcpy( cur, rec->cid, rec->cid_len );
452 cur += rec->cid_len;
453
454 *cur = rec->cid_len;
455 cur++;
456
457 MBEDTLS_PUT_UINT16_BE( ad_len_field, cur, 0 );
458 cur += 2;
459 }
460 else
461 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
462 {
463 MBEDTLS_PUT_UINT16_BE( ad_len_field, cur, 0 );
464 cur += 2;
465 }
466
467 *add_data_len = cur - add_data;
468 }
469
470 #if defined(MBEDTLS_GCM_C) || \
471 defined(MBEDTLS_CCM_C) || \
472 defined(MBEDTLS_CHACHAPOLY_C)
ssl_transform_aead_dynamic_iv_is_explicit(mbedtls_ssl_transform const * transform)473 static int ssl_transform_aead_dynamic_iv_is_explicit(
474 mbedtls_ssl_transform const *transform )
475 {
476 return( transform->ivlen != transform->fixed_ivlen );
477 }
478
479 /* Compute IV := ( fixed_iv || 0 ) XOR ( 0 || dynamic_IV )
480 *
481 * Concretely, this occurs in two variants:
482 *
483 * a) Fixed and dynamic IV lengths add up to total IV length, giving
484 * IV = fixed_iv || dynamic_iv
485 *
486 * This variant is used in TLS 1.2 when used with GCM or CCM.
487 *
488 * b) Fixed IV lengths matches total IV length, giving
489 * IV = fixed_iv XOR ( 0 || dynamic_iv )
490 *
491 * This variant occurs in TLS 1.3 and for TLS 1.2 when using ChaChaPoly.
492 *
493 * See also the documentation of mbedtls_ssl_transform.
494 *
495 * This function has the precondition that
496 *
497 * dst_iv_len >= max( fixed_iv_len, dynamic_iv_len )
498 *
499 * which has to be ensured by the caller. If this precondition
500 * violated, the behavior of this function is undefined.
501 */
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)502 static void ssl_build_record_nonce( unsigned char *dst_iv,
503 size_t dst_iv_len,
504 unsigned char const *fixed_iv,
505 size_t fixed_iv_len,
506 unsigned char const *dynamic_iv,
507 size_t dynamic_iv_len )
508 {
509 size_t i;
510
511 /* Start with Fixed IV || 0 */
512 memset( dst_iv, 0, dst_iv_len );
513 memcpy( dst_iv, fixed_iv, fixed_iv_len );
514
515 dst_iv += dst_iv_len - dynamic_iv_len;
516 for( i = 0; i < dynamic_iv_len; i++ )
517 dst_iv[i] ^= dynamic_iv[i];
518 }
519 #endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C || MBEDTLS_CHACHAPOLY_C */
520
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)521 int mbedtls_ssl_encrypt_buf( mbedtls_ssl_context *ssl,
522 mbedtls_ssl_transform *transform,
523 mbedtls_record *rec,
524 int (*f_rng)(void *, unsigned char *, size_t),
525 void *p_rng )
526 {
527 mbedtls_cipher_mode_t mode;
528 int auth_done = 0;
529 unsigned char * data;
530 unsigned char add_data[13 + 1 + MBEDTLS_SSL_CID_OUT_LEN_MAX ];
531 size_t add_data_len;
532 size_t post_avail;
533
534 /* The SSL context is only used for debugging purposes! */
535 #if !defined(MBEDTLS_DEBUG_C)
536 ssl = NULL; /* make sure we don't use it except for debug */
537 ((void) ssl);
538 #endif
539
540 /* The PRNG is used for dynamic IV generation that's used
541 * for CBC transformations in TLS 1.2. */
542 #if !( defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) && \
543 defined(MBEDTLS_SSL_PROTO_TLS1_2) )
544 ((void) f_rng);
545 ((void) p_rng);
546 #endif
547
548 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> encrypt buf" ) );
549
550 if( transform == NULL )
551 {
552 MBEDTLS_SSL_DEBUG_MSG( 1, ( "no transform provided to encrypt_buf" ) );
553 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
554 }
555 if( rec == NULL
556 || rec->buf == NULL
557 || rec->buf_len < rec->data_offset
558 || rec->buf_len - rec->data_offset < rec->data_len
559 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
560 || rec->cid_len != 0
561 #endif
562 )
563 {
564 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad record structure provided to encrypt_buf" ) );
565 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
566 }
567
568 data = rec->buf + rec->data_offset;
569 post_avail = rec->buf_len - ( rec->data_len + rec->data_offset );
570 MBEDTLS_SSL_DEBUG_BUF( 4, "before encrypt: output payload",
571 data, rec->data_len );
572
573 mode = mbedtls_cipher_get_cipher_mode( &transform->cipher_ctx_enc );
574
575 if( rec->data_len > MBEDTLS_SSL_OUT_CONTENT_LEN )
576 {
577 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Record content %" MBEDTLS_PRINTF_SIZET
578 " too large, maximum %" MBEDTLS_PRINTF_SIZET,
579 rec->data_len,
580 (size_t) MBEDTLS_SSL_OUT_CONTENT_LEN ) );
581 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
582 }
583
584 /* The following two code paths implement the (D)TLSInnerPlaintext
585 * structure present in TLS 1.3 and DTLS 1.2 + CID.
586 *
587 * See ssl_build_inner_plaintext() for more information.
588 *
589 * Note that this changes `rec->data_len`, and hence
590 * `post_avail` needs to be recalculated afterwards.
591 *
592 * Note also that the two code paths cannot occur simultaneously
593 * since they apply to different versions of the protocol. There
594 * is hence no risk of double-addition of the inner plaintext.
595 */
596 #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
597 if( transform->minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
598 {
599 size_t padding =
600 ssl_compute_padding_length( rec->data_len,
601 MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY );
602 if( ssl_build_inner_plaintext( data,
603 &rec->data_len,
604 post_avail,
605 rec->type,
606 padding ) != 0 )
607 {
608 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
609 }
610
611 rec->type = MBEDTLS_SSL_MSG_APPLICATION_DATA;
612 }
613 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
614
615 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
616 /*
617 * Add CID information
618 */
619 rec->cid_len = transform->out_cid_len;
620 memcpy( rec->cid, transform->out_cid, transform->out_cid_len );
621 MBEDTLS_SSL_DEBUG_BUF( 3, "CID", rec->cid, rec->cid_len );
622
623 if( rec->cid_len != 0 )
624 {
625 size_t padding =
626 ssl_compute_padding_length( rec->data_len,
627 MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY );
628 /*
629 * Wrap plaintext into DTLSInnerPlaintext structure.
630 * See ssl_build_inner_plaintext() for more information.
631 *
632 * Note that this changes `rec->data_len`, and hence
633 * `post_avail` needs to be recalculated afterwards.
634 */
635 if( ssl_build_inner_plaintext( data,
636 &rec->data_len,
637 post_avail,
638 rec->type,
639 padding ) != 0 )
640 {
641 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
642 }
643
644 rec->type = MBEDTLS_SSL_MSG_CID;
645 }
646 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
647
648 post_avail = rec->buf_len - ( rec->data_len + rec->data_offset );
649
650 /*
651 * Add MAC before if needed
652 */
653 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
654 if( mode == MBEDTLS_MODE_STREAM ||
655 ( mode == MBEDTLS_MODE_CBC
656 #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
657 && transform->encrypt_then_mac == MBEDTLS_SSL_ETM_DISABLED
658 #endif
659 ) )
660 {
661 if( post_avail < transform->maclen )
662 {
663 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
664 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
665 }
666 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
667 unsigned char mac[MBEDTLS_SSL_MAC_ADD];
668
669 ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
670 transform->minor_ver,
671 transform->taglen );
672
673 mbedtls_md_hmac_update( &transform->md_ctx_enc, add_data,
674 add_data_len );
675 mbedtls_md_hmac_update( &transform->md_ctx_enc, data, rec->data_len );
676 mbedtls_md_hmac_finish( &transform->md_ctx_enc, mac );
677 mbedtls_md_hmac_reset( &transform->md_ctx_enc );
678
679 memcpy( data + rec->data_len, mac, transform->maclen );
680 #endif
681
682 MBEDTLS_SSL_DEBUG_BUF( 4, "computed mac", data + rec->data_len,
683 transform->maclen );
684
685 rec->data_len += transform->maclen;
686 post_avail -= transform->maclen;
687 auth_done++;
688 }
689 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
690
691 /*
692 * Encrypt
693 */
694 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_STREAM)
695 if( mode == MBEDTLS_MODE_STREAM )
696 {
697 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
698 size_t olen;
699 MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", "
700 "including %d bytes of padding",
701 rec->data_len, 0 ) );
702
703 if( ( ret = mbedtls_cipher_crypt( &transform->cipher_ctx_enc,
704 transform->iv_enc, transform->ivlen,
705 data, rec->data_len,
706 data, &olen ) ) != 0 )
707 {
708 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
709 return( ret );
710 }
711
712 if( rec->data_len != olen )
713 {
714 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
715 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
716 }
717 }
718 else
719 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_STREAM */
720
721 #if defined(MBEDTLS_GCM_C) || \
722 defined(MBEDTLS_CCM_C) || \
723 defined(MBEDTLS_CHACHAPOLY_C)
724 if( mode == MBEDTLS_MODE_GCM ||
725 mode == MBEDTLS_MODE_CCM ||
726 mode == MBEDTLS_MODE_CHACHAPOLY )
727 {
728 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
729 unsigned char iv[12];
730 unsigned char *dynamic_iv;
731 size_t dynamic_iv_len;
732 int dynamic_iv_is_explicit =
733 ssl_transform_aead_dynamic_iv_is_explicit( transform );
734
735 /* Check that there's space for the authentication tag. */
736 if( post_avail < transform->taglen )
737 {
738 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
739 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
740 }
741
742 /*
743 * Build nonce for AEAD encryption.
744 *
745 * Note: In the case of CCM and GCM in TLS 1.2, the dynamic
746 * part of the IV is prepended to the ciphertext and
747 * can be chosen freely - in particular, it need not
748 * agree with the record sequence number.
749 * However, since ChaChaPoly as well as all AEAD modes
750 * in TLS 1.3 use the record sequence number as the
751 * dynamic part of the nonce, we uniformly use the
752 * record sequence number here in all cases.
753 */
754 dynamic_iv = rec->ctr;
755 dynamic_iv_len = sizeof( rec->ctr );
756
757 ssl_build_record_nonce( iv, sizeof( iv ),
758 transform->iv_enc,
759 transform->fixed_ivlen,
760 dynamic_iv,
761 dynamic_iv_len );
762
763 /*
764 * Build additional data for AEAD encryption.
765 * This depends on the TLS version.
766 */
767 ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
768 transform->minor_ver,
769 transform->taglen );
770
771 MBEDTLS_SSL_DEBUG_BUF( 4, "IV used (internal)",
772 iv, transform->ivlen );
773 MBEDTLS_SSL_DEBUG_BUF( 4, "IV used (transmitted)",
774 dynamic_iv,
775 dynamic_iv_is_explicit ? dynamic_iv_len : 0 );
776 MBEDTLS_SSL_DEBUG_BUF( 4, "additional data used for AEAD",
777 add_data, add_data_len );
778 MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", "
779 "including 0 bytes of padding",
780 rec->data_len ) );
781
782 /*
783 * Encrypt and authenticate
784 */
785
786 if( ( ret = mbedtls_cipher_auth_encrypt_ext( &transform->cipher_ctx_enc,
787 iv, transform->ivlen,
788 add_data, add_data_len,
789 data, rec->data_len, /* src */
790 data, rec->buf_len - (data - rec->buf), /* dst */
791 &rec->data_len,
792 transform->taglen ) ) != 0 )
793 {
794 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_auth_encrypt_ext", ret );
795 return( ret );
796 }
797 MBEDTLS_SSL_DEBUG_BUF( 4, "after encrypt: tag",
798 data + rec->data_len - transform->taglen,
799 transform->taglen );
800 /* Account for authentication tag. */
801 post_avail -= transform->taglen;
802
803 /*
804 * Prefix record content with dynamic IV in case it is explicit.
805 */
806 if( dynamic_iv_is_explicit != 0 )
807 {
808 if( rec->data_offset < dynamic_iv_len )
809 {
810 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
811 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
812 }
813
814 memcpy( data - dynamic_iv_len, dynamic_iv, dynamic_iv_len );
815 rec->data_offset -= dynamic_iv_len;
816 rec->data_len += dynamic_iv_len;
817 }
818
819 auth_done++;
820 }
821 else
822 #endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C || MBEDTLS_CHACHAPOLY_C */
823 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC)
824 if( mode == MBEDTLS_MODE_CBC )
825 {
826 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
827 size_t padlen, i;
828 size_t olen;
829
830 /* Currently we're always using minimal padding
831 * (up to 255 bytes would be allowed). */
832 padlen = transform->ivlen - ( rec->data_len + 1 ) % transform->ivlen;
833 if( padlen == transform->ivlen )
834 padlen = 0;
835
836 /* Check there's enough space in the buffer for the padding. */
837 if( post_avail < padlen + 1 )
838 {
839 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
840 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
841 }
842
843 for( i = 0; i <= padlen; i++ )
844 data[rec->data_len + i] = (unsigned char) padlen;
845
846 rec->data_len += padlen + 1;
847 post_avail -= padlen + 1;
848
849 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
850 /*
851 * Prepend per-record IV for block cipher in TLS v1.2 as per
852 * Method 1 (6.2.3.2. in RFC4346 and RFC5246)
853 */
854 if( f_rng == NULL )
855 {
856 MBEDTLS_SSL_DEBUG_MSG( 1, ( "No PRNG provided to encrypt_record routine" ) );
857 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
858 }
859
860 if( rec->data_offset < transform->ivlen )
861 {
862 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
863 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
864 }
865
866 /*
867 * Generate IV
868 */
869 ret = f_rng( p_rng, transform->iv_enc, transform->ivlen );
870 if( ret != 0 )
871 return( ret );
872
873 memcpy( data - transform->ivlen, transform->iv_enc, transform->ivlen );
874 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
875
876 MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", "
877 "including %" MBEDTLS_PRINTF_SIZET
878 " bytes of IV and %" MBEDTLS_PRINTF_SIZET " bytes of padding",
879 rec->data_len, transform->ivlen,
880 padlen + 1 ) );
881
882 if( ( ret = mbedtls_cipher_crypt( &transform->cipher_ctx_enc,
883 transform->iv_enc,
884 transform->ivlen,
885 data, rec->data_len,
886 data, &olen ) ) != 0 )
887 {
888 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
889 return( ret );
890 }
891
892 if( rec->data_len != olen )
893 {
894 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
895 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
896 }
897
898 data -= transform->ivlen;
899 rec->data_offset -= transform->ivlen;
900 rec->data_len += transform->ivlen;
901
902 #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
903 if( auth_done == 0 )
904 {
905 unsigned char mac[MBEDTLS_SSL_MAC_ADD];
906
907 /*
908 * MAC(MAC_write_key, seq_num +
909 * TLSCipherText.type +
910 * TLSCipherText.version +
911 * length_of( (IV +) ENC(...) ) +
912 * IV +
913 * ENC(content + padding + padding_length));
914 */
915
916 if( post_avail < transform->maclen)
917 {
918 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
919 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
920 }
921
922 ssl_extract_add_data_from_record( add_data, &add_data_len,
923 rec, transform->minor_ver,
924 transform->taglen );
925
926 MBEDTLS_SSL_DEBUG_MSG( 3, ( "using encrypt then mac" ) );
927 MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", add_data,
928 add_data_len );
929
930 mbedtls_md_hmac_update( &transform->md_ctx_enc, add_data,
931 add_data_len );
932 mbedtls_md_hmac_update( &transform->md_ctx_enc,
933 data, rec->data_len );
934 mbedtls_md_hmac_finish( &transform->md_ctx_enc, mac );
935 mbedtls_md_hmac_reset( &transform->md_ctx_enc );
936
937 memcpy( data + rec->data_len, mac, transform->maclen );
938
939 rec->data_len += transform->maclen;
940 post_avail -= transform->maclen;
941 auth_done++;
942 }
943 #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
944 }
945 else
946 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC) */
947 {
948 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
949 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
950 }
951
952 /* Make extra sure authentication was performed, exactly once */
953 if( auth_done != 1 )
954 {
955 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
956 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
957 }
958
959 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= encrypt buf" ) );
960
961 return( 0 );
962 }
963
964 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC)
965 /*
966 * Turn a bit into a mask:
967 * - if bit == 1, return the all-bits 1 mask, aka (size_t) -1
968 * - if bit == 0, return the all-bits 0 mask, aka 0
969 *
970 * This function can be used to write constant-time code by replacing branches
971 * with bit operations using masks.
972 *
973 * This function is implemented without using comparison operators, as those
974 * might be translated to branches by some compilers on some platforms.
975 */
mbedtls_ssl_cf_mask_from_bit(size_t bit)976 static size_t mbedtls_ssl_cf_mask_from_bit( size_t bit )
977 {
978 /* MSVC has a warning about unary minus on unsigned integer types,
979 * but this is well-defined and precisely what we want to do here. */
980 #if defined(_MSC_VER)
981 #pragma warning( push )
982 #pragma warning( disable : 4146 )
983 #endif
984 return -bit;
985 #if defined(_MSC_VER)
986 #pragma warning( pop )
987 #endif
988 }
989
990 /*
991 * Constant-flow mask generation for "less than" comparison:
992 * - if x < y, return all bits 1, that is (size_t) -1
993 * - otherwise, return all bits 0, that is 0
994 *
995 * This function can be used to write constant-time code by replacing branches
996 * with bit operations using masks.
997 *
998 * This function is implemented without using comparison operators, as those
999 * might be translated to branches by some compilers on some platforms.
1000 */
mbedtls_ssl_cf_mask_lt(size_t x,size_t y)1001 static size_t mbedtls_ssl_cf_mask_lt( size_t x, size_t y )
1002 {
1003 /* This has the most significant bit set if and only if x < y */
1004 const size_t sub = x - y;
1005
1006 /* sub1 = (x < y) ? 1 : 0 */
1007 const size_t sub1 = sub >> ( sizeof( sub ) * 8 - 1 );
1008
1009 /* mask = (x < y) ? 0xff... : 0x00... */
1010 const size_t mask = mbedtls_ssl_cf_mask_from_bit( sub1 );
1011
1012 return( mask );
1013 }
1014
1015 /*
1016 * Constant-flow mask generation for "greater or equal" comparison:
1017 * - if x >= y, return all bits 1, that is (size_t) -1
1018 * - otherwise, return all bits 0, that is 0
1019 *
1020 * This function can be used to write constant-time code by replacing branches
1021 * with bit operations using masks.
1022 *
1023 * This function is implemented without using comparison operators, as those
1024 * might be translated to branches by some compilers on some platforms.
1025 */
mbedtls_ssl_cf_mask_ge(size_t x,size_t y)1026 static size_t mbedtls_ssl_cf_mask_ge( size_t x, size_t y )
1027 {
1028 return( ~mbedtls_ssl_cf_mask_lt( x, y ) );
1029 }
1030
1031 /*
1032 * Constant-flow boolean "equal" comparison:
1033 * return x == y
1034 *
1035 * This function can be used to write constant-time code by replacing branches
1036 * with bit operations - it can be used in conjunction with
1037 * mbedtls_ssl_cf_mask_from_bit().
1038 *
1039 * This function is implemented without using comparison operators, as those
1040 * might be translated to branches by some compilers on some platforms.
1041 */
mbedtls_ssl_cf_bool_eq(size_t x,size_t y)1042 static size_t mbedtls_ssl_cf_bool_eq( size_t x, size_t y )
1043 {
1044 /* diff = 0 if x == y, non-zero otherwise */
1045 const size_t diff = x ^ y;
1046
1047 /* MSVC has a warning about unary minus on unsigned integer types,
1048 * but this is well-defined and precisely what we want to do here. */
1049 #if defined(_MSC_VER)
1050 #pragma warning( push )
1051 #pragma warning( disable : 4146 )
1052 #endif
1053
1054 /* diff_msb's most significant bit is equal to x != y */
1055 const size_t diff_msb = ( diff | -diff );
1056
1057 #if defined(_MSC_VER)
1058 #pragma warning( pop )
1059 #endif
1060
1061 /* diff1 = (x != y) ? 1 : 0 */
1062 const size_t diff1 = diff_msb >> ( sizeof( diff_msb ) * 8 - 1 );
1063
1064 return( 1 ^ diff1 );
1065 }
1066
1067 /*
1068 * Constant-flow conditional memcpy:
1069 * - if c1 == c2, equivalent to memcpy(dst, src, len),
1070 * - otherwise, a no-op,
1071 * but with execution flow independent of the values of c1 and c2.
1072 *
1073 * This function is implemented without using comparison operators, as those
1074 * might be translated to branches by some compilers on some platforms.
1075 */
mbedtls_ssl_cf_memcpy_if_eq(unsigned char * dst,const unsigned char * src,size_t len,size_t c1,size_t c2)1076 static void mbedtls_ssl_cf_memcpy_if_eq( unsigned char *dst,
1077 const unsigned char *src,
1078 size_t len,
1079 size_t c1, size_t c2 )
1080 {
1081 /* mask = c1 == c2 ? 0xff : 0x00 */
1082 const size_t equal = mbedtls_ssl_cf_bool_eq( c1, c2 );
1083 const unsigned char mask = (unsigned char) mbedtls_ssl_cf_mask_from_bit( equal );
1084
1085 /* dst[i] = c1 == c2 ? src[i] : dst[i] */
1086 for( size_t i = 0; i < len; i++ )
1087 dst[i] = ( src[i] & mask ) | ( dst[i] & ~mask );
1088 }
1089
1090 /*
1091 * Compute HMAC of variable-length data with constant flow.
1092 *
1093 * Only works with MD-5, SHA-1, SHA-256 and SHA-384.
1094 * (Otherwise, computation of block_size needs to be adapted.)
1095 */
mbedtls_ssl_cf_hmac(mbedtls_md_context_t * ctx,const unsigned char * add_data,size_t add_data_len,const unsigned char * data,size_t data_len_secret,size_t min_data_len,size_t max_data_len,unsigned char * output)1096 MBEDTLS_STATIC_TESTABLE int mbedtls_ssl_cf_hmac(
1097 mbedtls_md_context_t *ctx,
1098 const unsigned char *add_data, size_t add_data_len,
1099 const unsigned char *data, size_t data_len_secret,
1100 size_t min_data_len, size_t max_data_len,
1101 unsigned char *output )
1102 {
1103 /*
1104 * This function breaks the HMAC abstraction and uses the md_clone()
1105 * extension to the MD API in order to get constant-flow behaviour.
1106 *
1107 * HMAC(msg) is defined as HASH(okey + HASH(ikey + msg)) where + means
1108 * concatenation, and okey/ikey are the XOR of the key with some fixed bit
1109 * patterns (see RFC 2104, sec. 2), which are stored in ctx->hmac_ctx.
1110 *
1111 * We'll first compute inner_hash = HASH(ikey + msg) by hashing up to
1112 * minlen, then cloning the context, and for each byte up to maxlen
1113 * finishing up the hash computation, keeping only the correct result.
1114 *
1115 * Then we only need to compute HASH(okey + inner_hash) and we're done.
1116 */
1117 const mbedtls_md_type_t md_alg = mbedtls_md_get_type( ctx->md_info );
1118 /* TLS 1.2 only supports SHA-384, SHA-256, SHA-1, MD-5,
1119 * all of which have the same block size except SHA-384. */
1120 const size_t block_size = md_alg == MBEDTLS_MD_SHA384 ? 128 : 64;
1121 const unsigned char * const ikey = ctx->hmac_ctx;
1122 const unsigned char * const okey = ikey + block_size;
1123 const size_t hash_size = mbedtls_md_get_size( ctx->md_info );
1124
1125 unsigned char aux_out[MBEDTLS_MD_MAX_SIZE];
1126 mbedtls_md_context_t aux;
1127 size_t offset;
1128 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1129
1130 mbedtls_md_init( &aux );
1131
1132 #define MD_CHK( func_call ) \
1133 do { \
1134 ret = (func_call); \
1135 if( ret != 0 ) \
1136 goto cleanup; \
1137 } while( 0 )
1138
1139 MD_CHK( mbedtls_md_setup( &aux, ctx->md_info, 0 ) );
1140
1141 /* After hmac_start() of hmac_reset(), ikey has already been hashed,
1142 * so we can start directly with the message */
1143 MD_CHK( mbedtls_md_update( ctx, add_data, add_data_len ) );
1144 MD_CHK( mbedtls_md_update( ctx, data, min_data_len ) );
1145
1146 /* For each possible length, compute the hash up to that point */
1147 for( offset = min_data_len; offset <= max_data_len; offset++ )
1148 {
1149 MD_CHK( mbedtls_md_clone( &aux, ctx ) );
1150 MD_CHK( mbedtls_md_finish( &aux, aux_out ) );
1151 /* Keep only the correct inner_hash in the output buffer */
1152 mbedtls_ssl_cf_memcpy_if_eq( output, aux_out, hash_size,
1153 offset, data_len_secret );
1154
1155 if( offset < max_data_len )
1156 MD_CHK( mbedtls_md_update( ctx, data + offset, 1 ) );
1157 }
1158
1159 /* The context needs to finish() before it starts() again */
1160 MD_CHK( mbedtls_md_finish( ctx, aux_out ) );
1161
1162 /* Now compute HASH(okey + inner_hash) */
1163 MD_CHK( mbedtls_md_starts( ctx ) );
1164 MD_CHK( mbedtls_md_update( ctx, okey, block_size ) );
1165 MD_CHK( mbedtls_md_update( ctx, output, hash_size ) );
1166 MD_CHK( mbedtls_md_finish( ctx, output ) );
1167
1168 /* Done, get ready for next time */
1169 MD_CHK( mbedtls_md_hmac_reset( ctx ) );
1170
1171 #undef MD_CHK
1172
1173 cleanup:
1174 mbedtls_md_free( &aux );
1175 return( ret );
1176 }
1177
1178 /*
1179 * Constant-flow memcpy from variable position in buffer.
1180 * - functionally equivalent to memcpy(dst, src + offset_secret, len)
1181 * - but with execution flow independent from the value of offset_secret.
1182 */
mbedtls_ssl_cf_memcpy_offset(unsigned char * dst,const unsigned char * src_base,size_t offset_secret,size_t offset_min,size_t offset_max,size_t len)1183 MBEDTLS_STATIC_TESTABLE void mbedtls_ssl_cf_memcpy_offset(
1184 unsigned char *dst,
1185 const unsigned char *src_base,
1186 size_t offset_secret,
1187 size_t offset_min, size_t offset_max,
1188 size_t len )
1189 {
1190 size_t offset;
1191
1192 for( offset = offset_min; offset <= offset_max; offset++ )
1193 {
1194 mbedtls_ssl_cf_memcpy_if_eq( dst, src_base + offset, len,
1195 offset, offset_secret );
1196 }
1197 }
1198 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC */
1199
mbedtls_ssl_decrypt_buf(mbedtls_ssl_context const * ssl,mbedtls_ssl_transform * transform,mbedtls_record * rec)1200 int mbedtls_ssl_decrypt_buf( mbedtls_ssl_context const *ssl,
1201 mbedtls_ssl_transform *transform,
1202 mbedtls_record *rec )
1203 {
1204 size_t olen;
1205 mbedtls_cipher_mode_t mode;
1206 int ret, auth_done = 0;
1207 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
1208 size_t padlen = 0, correct = 1;
1209 #endif
1210 unsigned char* data;
1211 unsigned char add_data[13 + 1 + MBEDTLS_SSL_CID_IN_LEN_MAX ];
1212 size_t add_data_len;
1213
1214 #if !defined(MBEDTLS_DEBUG_C)
1215 ssl = NULL; /* make sure we don't use it except for debug */
1216 ((void) ssl);
1217 #endif
1218
1219 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> decrypt buf" ) );
1220 if( rec == NULL ||
1221 rec->buf == NULL ||
1222 rec->buf_len < rec->data_offset ||
1223 rec->buf_len - rec->data_offset < rec->data_len )
1224 {
1225 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad record structure provided to decrypt_buf" ) );
1226 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
1227 }
1228
1229 data = rec->buf + rec->data_offset;
1230 mode = mbedtls_cipher_get_cipher_mode( &transform->cipher_ctx_dec );
1231
1232 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1233 /*
1234 * Match record's CID with incoming CID.
1235 */
1236 if( rec->cid_len != transform->in_cid_len ||
1237 memcmp( rec->cid, transform->in_cid, rec->cid_len ) != 0 )
1238 {
1239 return( MBEDTLS_ERR_SSL_UNEXPECTED_CID );
1240 }
1241 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
1242
1243 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_STREAM)
1244 if( mode == MBEDTLS_MODE_STREAM )
1245 {
1246 padlen = 0;
1247 if( ( ret = mbedtls_cipher_crypt( &transform->cipher_ctx_dec,
1248 transform->iv_dec,
1249 transform->ivlen,
1250 data, rec->data_len,
1251 data, &olen ) ) != 0 )
1252 {
1253 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
1254 return( ret );
1255 }
1256
1257 if( rec->data_len != olen )
1258 {
1259 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
1260 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
1261 }
1262 }
1263 else
1264 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_STREAM */
1265 #if defined(MBEDTLS_GCM_C) || \
1266 defined(MBEDTLS_CCM_C) || \
1267 defined(MBEDTLS_CHACHAPOLY_C)
1268 if( mode == MBEDTLS_MODE_GCM ||
1269 mode == MBEDTLS_MODE_CCM ||
1270 mode == MBEDTLS_MODE_CHACHAPOLY )
1271 {
1272 unsigned char iv[12];
1273 unsigned char *dynamic_iv;
1274 size_t dynamic_iv_len;
1275
1276 /*
1277 * Extract dynamic part of nonce for AEAD decryption.
1278 *
1279 * Note: In the case of CCM and GCM in TLS 1.2, the dynamic
1280 * part of the IV is prepended to the ciphertext and
1281 * can be chosen freely - in particular, it need not
1282 * agree with the record sequence number.
1283 */
1284 dynamic_iv_len = sizeof( rec->ctr );
1285 if( ssl_transform_aead_dynamic_iv_is_explicit( transform ) == 1 )
1286 {
1287 if( rec->data_len < dynamic_iv_len )
1288 {
1289 MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%" MBEDTLS_PRINTF_SIZET
1290 " ) < explicit_iv_len (%" MBEDTLS_PRINTF_SIZET ") ",
1291 rec->data_len,
1292 dynamic_iv_len ) );
1293 return( MBEDTLS_ERR_SSL_INVALID_MAC );
1294 }
1295 dynamic_iv = data;
1296
1297 data += dynamic_iv_len;
1298 rec->data_offset += dynamic_iv_len;
1299 rec->data_len -= dynamic_iv_len;
1300 }
1301 else
1302 {
1303 dynamic_iv = rec->ctr;
1304 }
1305
1306 /* Check that there's space for the authentication tag. */
1307 if( rec->data_len < transform->taglen )
1308 {
1309 MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%" MBEDTLS_PRINTF_SIZET
1310 ") < taglen (%" MBEDTLS_PRINTF_SIZET ") ",
1311 rec->data_len,
1312 transform->taglen ) );
1313 return( MBEDTLS_ERR_SSL_INVALID_MAC );
1314 }
1315 rec->data_len -= transform->taglen;
1316
1317 /*
1318 * Prepare nonce from dynamic and static parts.
1319 */
1320 ssl_build_record_nonce( iv, sizeof( iv ),
1321 transform->iv_dec,
1322 transform->fixed_ivlen,
1323 dynamic_iv,
1324 dynamic_iv_len );
1325
1326 /*
1327 * Build additional data for AEAD encryption.
1328 * This depends on the TLS version.
1329 */
1330 ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
1331 transform->minor_ver,
1332 transform->taglen );
1333 MBEDTLS_SSL_DEBUG_BUF( 4, "additional data used for AEAD",
1334 add_data, add_data_len );
1335
1336 /* Because of the check above, we know that there are
1337 * explicit_iv_len Bytes preceeding data, and taglen
1338 * bytes following data + data_len. This justifies
1339 * the debug message and the invocation of
1340 * mbedtls_cipher_auth_decrypt_ext() below. */
1341
1342 MBEDTLS_SSL_DEBUG_BUF( 4, "IV used", iv, transform->ivlen );
1343 MBEDTLS_SSL_DEBUG_BUF( 4, "TAG used", data + rec->data_len,
1344 transform->taglen );
1345
1346 /*
1347 * Decrypt and authenticate
1348 */
1349 if( ( ret = mbedtls_cipher_auth_decrypt_ext( &transform->cipher_ctx_dec,
1350 iv, transform->ivlen,
1351 add_data, add_data_len,
1352 data, rec->data_len + transform->taglen, /* src */
1353 data, rec->buf_len - (data - rec->buf), &olen, /* dst */
1354 transform->taglen ) ) != 0 )
1355 {
1356 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_auth_decrypt_ext", ret );
1357
1358 if( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED )
1359 return( MBEDTLS_ERR_SSL_INVALID_MAC );
1360
1361 return( ret );
1362 }
1363 auth_done++;
1364
1365 /* Double-check that AEAD decryption doesn't change content length. */
1366 if( olen != rec->data_len )
1367 {
1368 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
1369 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
1370 }
1371 }
1372 else
1373 #endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C */
1374 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC)
1375 if( mode == MBEDTLS_MODE_CBC )
1376 {
1377 size_t minlen = 0;
1378
1379 /*
1380 * Check immediate ciphertext sanity
1381 */
1382 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
1383 /* The ciphertext is prefixed with the CBC IV. */
1384 minlen += transform->ivlen;
1385 #endif
1386
1387 /* Size considerations:
1388 *
1389 * - The CBC cipher text must not be empty and hence
1390 * at least of size transform->ivlen.
1391 *
1392 * Together with the potential IV-prefix, this explains
1393 * the first of the two checks below.
1394 *
1395 * - The record must contain a MAC, either in plain or
1396 * encrypted, depending on whether Encrypt-then-MAC
1397 * is used or not.
1398 * - If it is, the message contains the IV-prefix,
1399 * the CBC ciphertext, and the MAC.
1400 * - If it is not, the padded plaintext, and hence
1401 * the CBC ciphertext, has at least length maclen + 1
1402 * because there is at least the padding length byte.
1403 *
1404 * As the CBC ciphertext is not empty, both cases give the
1405 * lower bound minlen + maclen + 1 on the record size, which
1406 * we test for in the second check below.
1407 */
1408 if( rec->data_len < minlen + transform->ivlen ||
1409 rec->data_len < minlen + transform->maclen + 1 )
1410 {
1411 MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%" MBEDTLS_PRINTF_SIZET
1412 ") < max( ivlen(%" MBEDTLS_PRINTF_SIZET
1413 "), maclen (%" MBEDTLS_PRINTF_SIZET ") "
1414 "+ 1 ) ( + expl IV )", rec->data_len,
1415 transform->ivlen,
1416 transform->maclen ) );
1417 return( MBEDTLS_ERR_SSL_INVALID_MAC );
1418 }
1419
1420 /*
1421 * Authenticate before decrypt if enabled
1422 */
1423 #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
1424 if( transform->encrypt_then_mac == MBEDTLS_SSL_ETM_ENABLED )
1425 {
1426 unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
1427
1428 MBEDTLS_SSL_DEBUG_MSG( 3, ( "using encrypt then mac" ) );
1429
1430 /* Update data_len in tandem with add_data.
1431 *
1432 * The subtraction is safe because of the previous check
1433 * data_len >= minlen + maclen + 1.
1434 *
1435 * Afterwards, we know that data + data_len is followed by at
1436 * least maclen Bytes, which justifies the call to
1437 * mbedtls_ssl_safer_memcmp() below.
1438 *
1439 * Further, we still know that data_len > minlen */
1440 rec->data_len -= transform->maclen;
1441 ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
1442 transform->minor_ver,
1443 transform->taglen );
1444
1445 /* Calculate expected MAC. */
1446 MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", add_data,
1447 add_data_len );
1448 mbedtls_md_hmac_update( &transform->md_ctx_dec, add_data,
1449 add_data_len );
1450 mbedtls_md_hmac_update( &transform->md_ctx_dec,
1451 data, rec->data_len );
1452 mbedtls_md_hmac_finish( &transform->md_ctx_dec, mac_expect );
1453 mbedtls_md_hmac_reset( &transform->md_ctx_dec );
1454
1455 MBEDTLS_SSL_DEBUG_BUF( 4, "message mac", data + rec->data_len,
1456 transform->maclen );
1457 MBEDTLS_SSL_DEBUG_BUF( 4, "expected mac", mac_expect,
1458 transform->maclen );
1459
1460 /* Compare expected MAC with MAC at the end of the record. */
1461 if( mbedtls_ssl_safer_memcmp( data + rec->data_len, mac_expect,
1462 transform->maclen ) != 0 )
1463 {
1464 MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
1465 return( MBEDTLS_ERR_SSL_INVALID_MAC );
1466 }
1467 auth_done++;
1468 }
1469 #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
1470
1471 /*
1472 * Check length sanity
1473 */
1474
1475 /* We know from above that data_len > minlen >= 0,
1476 * so the following check in particular implies that
1477 * data_len >= minlen + ivlen ( = minlen or 2 * minlen ). */
1478 if( rec->data_len % transform->ivlen != 0 )
1479 {
1480 MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%" MBEDTLS_PRINTF_SIZET
1481 ") %% ivlen (%" MBEDTLS_PRINTF_SIZET ") != 0",
1482 rec->data_len, transform->ivlen ) );
1483 return( MBEDTLS_ERR_SSL_INVALID_MAC );
1484 }
1485
1486 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
1487 /*
1488 * Initialize for prepended IV for block cipher in TLS v1.2
1489 */
1490 /* Safe because data_len >= minlen + ivlen = 2 * ivlen. */
1491 memcpy( transform->iv_dec, data, transform->ivlen );
1492
1493 data += transform->ivlen;
1494 rec->data_offset += transform->ivlen;
1495 rec->data_len -= transform->ivlen;
1496 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
1497
1498 /* We still have data_len % ivlen == 0 and data_len >= ivlen here. */
1499
1500 if( ( ret = mbedtls_cipher_crypt( &transform->cipher_ctx_dec,
1501 transform->iv_dec, transform->ivlen,
1502 data, rec->data_len, data, &olen ) ) != 0 )
1503 {
1504 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
1505 return( ret );
1506 }
1507
1508 /* Double-check that length hasn't changed during decryption. */
1509 if( rec->data_len != olen )
1510 {
1511 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
1512 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
1513 }
1514
1515 /* Safe since data_len >= minlen + maclen + 1, so after having
1516 * subtracted at most minlen and maclen up to this point,
1517 * data_len > 0 (because of data_len % ivlen == 0, it's actually
1518 * >= ivlen ). */
1519 padlen = data[rec->data_len - 1];
1520
1521 if( auth_done == 1 )
1522 {
1523 const size_t mask = mbedtls_ssl_cf_mask_ge(
1524 rec->data_len,
1525 padlen + 1 );
1526 correct &= mask;
1527 padlen &= mask;
1528 }
1529 else
1530 {
1531 #if defined(MBEDTLS_SSL_DEBUG_ALL)
1532 if( rec->data_len < transform->maclen + padlen + 1 )
1533 {
1534 MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%" MBEDTLS_PRINTF_SIZET
1535 ") < maclen (%" MBEDTLS_PRINTF_SIZET
1536 ") + padlen (%" MBEDTLS_PRINTF_SIZET ")",
1537 rec->data_len,
1538 transform->maclen,
1539 padlen + 1 ) );
1540 }
1541 #endif
1542
1543 const size_t mask = mbedtls_ssl_cf_mask_ge(
1544 rec->data_len,
1545 transform->maclen + padlen + 1 );
1546 correct &= mask;
1547 padlen &= mask;
1548 }
1549
1550 padlen++;
1551
1552 /* Regardless of the validity of the padding,
1553 * we have data_len >= padlen here. */
1554
1555 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
1556 /* The padding check involves a series of up to 256
1557 * consecutive memory reads at the end of the record
1558 * plaintext buffer. In order to hide the length and
1559 * validity of the padding, always perform exactly
1560 * `min(256,plaintext_len)` reads (but take into account
1561 * only the last `padlen` bytes for the padding check). */
1562 size_t pad_count = 0;
1563 volatile unsigned char* const check = data;
1564
1565 /* Index of first padding byte; it has been ensured above
1566 * that the subtraction is safe. */
1567 size_t const padding_idx = rec->data_len - padlen;
1568 size_t const num_checks = rec->data_len <= 256 ? rec->data_len : 256;
1569 size_t const start_idx = rec->data_len - num_checks;
1570 size_t idx;
1571
1572 for( idx = start_idx; idx < rec->data_len; idx++ )
1573 {
1574 /* pad_count += (idx >= padding_idx) &&
1575 * (check[idx] == padlen - 1);
1576 */
1577 const size_t mask = mbedtls_ssl_cf_mask_ge( idx, padding_idx );
1578 const size_t equal = mbedtls_ssl_cf_bool_eq( check[idx],
1579 padlen - 1 );
1580 pad_count += mask & equal;
1581 }
1582 correct &= mbedtls_ssl_cf_bool_eq( pad_count, padlen );
1583
1584 #if defined(MBEDTLS_SSL_DEBUG_ALL)
1585 if( padlen > 0 && correct == 0 )
1586 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad padding byte detected" ) );
1587 #endif
1588 padlen &= mbedtls_ssl_cf_mask_from_bit( correct );
1589
1590 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
1591
1592 /* If the padding was found to be invalid, padlen == 0
1593 * and the subtraction is safe. If the padding was found valid,
1594 * padlen hasn't been changed and the previous assertion
1595 * data_len >= padlen still holds. */
1596 rec->data_len -= padlen;
1597 }
1598 else
1599 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC */
1600 {
1601 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
1602 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
1603 }
1604
1605 #if defined(MBEDTLS_SSL_DEBUG_ALL)
1606 MBEDTLS_SSL_DEBUG_BUF( 4, "raw buffer after decryption",
1607 data, rec->data_len );
1608 #endif
1609
1610 /*
1611 * Authenticate if not done yet.
1612 * Compute the MAC regardless of the padding result (RFC4346, CBCTIME).
1613 */
1614 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
1615 if( auth_done == 0 )
1616 {
1617 unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
1618 unsigned char mac_peer[MBEDTLS_SSL_MAC_ADD];
1619
1620 /* If the initial value of padlen was such that
1621 * data_len < maclen + padlen + 1, then padlen
1622 * got reset to 1, and the initial check
1623 * data_len >= minlen + maclen + 1
1624 * guarantees that at this point we still
1625 * have at least data_len >= maclen.
1626 *
1627 * If the initial value of padlen was such that
1628 * data_len >= maclen + padlen + 1, then we have
1629 * subtracted either padlen + 1 (if the padding was correct)
1630 * or 0 (if the padding was incorrect) since then,
1631 * hence data_len >= maclen in any case.
1632 */
1633 rec->data_len -= transform->maclen;
1634 ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
1635 transform->minor_ver,
1636 transform->taglen );
1637
1638 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
1639 /*
1640 * The next two sizes are the minimum and maximum values of
1641 * data_len over all padlen values.
1642 *
1643 * They're independent of padlen, since we previously did
1644 * data_len -= padlen.
1645 *
1646 * Note that max_len + maclen is never more than the buffer
1647 * length, as we previously did in_msglen -= maclen too.
1648 */
1649 const size_t max_len = rec->data_len + padlen;
1650 const size_t min_len = ( max_len > 256 ) ? max_len - 256 : 0;
1651
1652 ret = mbedtls_ssl_cf_hmac( &transform->md_ctx_dec,
1653 add_data, add_data_len,
1654 data, rec->data_len, min_len, max_len,
1655 mac_expect );
1656 if( ret != 0 )
1657 {
1658 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_cf_hmac", ret );
1659 return( ret );
1660 }
1661
1662 mbedtls_ssl_cf_memcpy_offset( mac_peer, data,
1663 rec->data_len,
1664 min_len, max_len,
1665 transform->maclen );
1666 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
1667
1668 #if defined(MBEDTLS_SSL_DEBUG_ALL)
1669 MBEDTLS_SSL_DEBUG_BUF( 4, "expected mac", mac_expect, transform->maclen );
1670 MBEDTLS_SSL_DEBUG_BUF( 4, "message mac", mac_peer, transform->maclen );
1671 #endif
1672
1673 if( mbedtls_ssl_safer_memcmp( mac_peer, mac_expect,
1674 transform->maclen ) != 0 )
1675 {
1676 #if defined(MBEDTLS_SSL_DEBUG_ALL)
1677 MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
1678 #endif
1679 correct = 0;
1680 }
1681 auth_done++;
1682 }
1683
1684 /*
1685 * Finally check the correct flag
1686 */
1687 if( correct == 0 )
1688 return( MBEDTLS_ERR_SSL_INVALID_MAC );
1689 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
1690
1691 /* Make extra sure authentication was performed, exactly once */
1692 if( auth_done != 1 )
1693 {
1694 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
1695 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
1696 }
1697
1698 #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
1699 if( transform->minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
1700 {
1701 /* Remove inner padding and infer true content type. */
1702 ret = ssl_parse_inner_plaintext( data, &rec->data_len,
1703 &rec->type );
1704
1705 if( ret != 0 )
1706 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
1707 }
1708 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
1709
1710 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1711 if( rec->cid_len != 0 )
1712 {
1713 ret = ssl_parse_inner_plaintext( data, &rec->data_len,
1714 &rec->type );
1715 if( ret != 0 )
1716 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
1717 }
1718 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
1719
1720 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= decrypt buf" ) );
1721
1722 return( 0 );
1723 }
1724
1725 #undef MAC_NONE
1726 #undef MAC_PLAINTEXT
1727 #undef MAC_CIPHERTEXT
1728
1729 /*
1730 * Fill the input message buffer by appending data to it.
1731 * The amount of data already fetched is in ssl->in_left.
1732 *
1733 * If we return 0, is it guaranteed that (at least) nb_want bytes are
1734 * available (from this read and/or a previous one). Otherwise, an error code
1735 * is returned (possibly EOF or WANT_READ).
1736 *
1737 * With stream transport (TLS) on success ssl->in_left == nb_want, but
1738 * with datagram transport (DTLS) on success ssl->in_left >= nb_want,
1739 * since we always read a whole datagram at once.
1740 *
1741 * For DTLS, it is up to the caller to set ssl->next_record_offset when
1742 * they're done reading a record.
1743 */
mbedtls_ssl_fetch_input(mbedtls_ssl_context * ssl,size_t nb_want)1744 int mbedtls_ssl_fetch_input( mbedtls_ssl_context *ssl, size_t nb_want )
1745 {
1746 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1747 size_t len;
1748 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
1749 size_t in_buf_len = ssl->in_buf_len;
1750 #else
1751 size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN;
1752 #endif
1753
1754 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> fetch input" ) );
1755
1756 if( ssl->f_recv == NULL && ssl->f_recv_timeout == NULL )
1757 {
1758 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Bad usage of mbedtls_ssl_set_bio() "
1759 "or mbedtls_ssl_set_bio()" ) );
1760 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
1761 }
1762
1763 if( nb_want > in_buf_len - (size_t)( ssl->in_hdr - ssl->in_buf ) )
1764 {
1765 MBEDTLS_SSL_DEBUG_MSG( 1, ( "requesting more data than fits" ) );
1766 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
1767 }
1768
1769 #if defined(MBEDTLS_SSL_PROTO_DTLS)
1770 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
1771 {
1772 uint32_t timeout;
1773
1774 /*
1775 * The point is, we need to always read a full datagram at once, so we
1776 * sometimes read more then requested, and handle the additional data.
1777 * It could be the rest of the current record (while fetching the
1778 * header) and/or some other records in the same datagram.
1779 */
1780
1781 /*
1782 * Move to the next record in the already read datagram if applicable
1783 */
1784 if( ssl->next_record_offset != 0 )
1785 {
1786 if( ssl->in_left < ssl->next_record_offset )
1787 {
1788 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
1789 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
1790 }
1791
1792 ssl->in_left -= ssl->next_record_offset;
1793
1794 if( ssl->in_left != 0 )
1795 {
1796 MBEDTLS_SSL_DEBUG_MSG( 2, ( "next record in same datagram, offset: %"
1797 MBEDTLS_PRINTF_SIZET,
1798 ssl->next_record_offset ) );
1799 memmove( ssl->in_hdr,
1800 ssl->in_hdr + ssl->next_record_offset,
1801 ssl->in_left );
1802 }
1803
1804 ssl->next_record_offset = 0;
1805 }
1806
1807 MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %" MBEDTLS_PRINTF_SIZET
1808 ", nb_want: %" MBEDTLS_PRINTF_SIZET,
1809 ssl->in_left, nb_want ) );
1810
1811 /*
1812 * Done if we already have enough data.
1813 */
1814 if( nb_want <= ssl->in_left)
1815 {
1816 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= fetch input" ) );
1817 return( 0 );
1818 }
1819
1820 /*
1821 * A record can't be split across datagrams. If we need to read but
1822 * are not at the beginning of a new record, the caller did something
1823 * wrong.
1824 */
1825 if( ssl->in_left != 0 )
1826 {
1827 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
1828 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
1829 }
1830
1831 /*
1832 * Don't even try to read if time's out already.
1833 * This avoids by-passing the timer when repeatedly receiving messages
1834 * that will end up being dropped.
1835 */
1836 if( mbedtls_ssl_check_timer( ssl ) != 0 )
1837 {
1838 MBEDTLS_SSL_DEBUG_MSG( 2, ( "timer has expired" ) );
1839 ret = MBEDTLS_ERR_SSL_TIMEOUT;
1840 }
1841 else
1842 {
1843 len = in_buf_len - ( ssl->in_hdr - ssl->in_buf );
1844
1845 if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
1846 timeout = ssl->handshake->retransmit_timeout;
1847 else
1848 timeout = ssl->conf->read_timeout;
1849
1850 MBEDTLS_SSL_DEBUG_MSG( 3, ( "f_recv_timeout: %lu ms", (unsigned long) timeout ) );
1851
1852 if( ssl->f_recv_timeout != NULL )
1853 ret = ssl->f_recv_timeout( ssl->p_bio, ssl->in_hdr, len,
1854 timeout );
1855 else
1856 ret = ssl->f_recv( ssl->p_bio, ssl->in_hdr, len );
1857
1858 MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_recv(_timeout)", ret );
1859
1860 if( ret == 0 )
1861 return( MBEDTLS_ERR_SSL_CONN_EOF );
1862 }
1863
1864 if( ret == MBEDTLS_ERR_SSL_TIMEOUT )
1865 {
1866 MBEDTLS_SSL_DEBUG_MSG( 2, ( "timeout" ) );
1867 mbedtls_ssl_set_timer( ssl, 0 );
1868
1869 if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
1870 {
1871 if( ssl_double_retransmit_timeout( ssl ) != 0 )
1872 {
1873 MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake timeout" ) );
1874 return( MBEDTLS_ERR_SSL_TIMEOUT );
1875 }
1876
1877 if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
1878 {
1879 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend", ret );
1880 return( ret );
1881 }
1882
1883 return( MBEDTLS_ERR_SSL_WANT_READ );
1884 }
1885 #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
1886 else if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
1887 ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
1888 {
1889 if( ( ret = mbedtls_ssl_resend_hello_request( ssl ) ) != 0 )
1890 {
1891 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend_hello_request",
1892 ret );
1893 return( ret );
1894 }
1895
1896 return( MBEDTLS_ERR_SSL_WANT_READ );
1897 }
1898 #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
1899 }
1900
1901 if( ret < 0 )
1902 return( ret );
1903
1904 ssl->in_left = ret;
1905 }
1906 else
1907 #endif
1908 {
1909 MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %" MBEDTLS_PRINTF_SIZET
1910 ", nb_want: %" MBEDTLS_PRINTF_SIZET,
1911 ssl->in_left, nb_want ) );
1912
1913 while( ssl->in_left < nb_want )
1914 {
1915 len = nb_want - ssl->in_left;
1916
1917 if( mbedtls_ssl_check_timer( ssl ) != 0 )
1918 ret = MBEDTLS_ERR_SSL_TIMEOUT;
1919 else
1920 {
1921 if( ssl->f_recv_timeout != NULL )
1922 {
1923 ret = ssl->f_recv_timeout( ssl->p_bio,
1924 ssl->in_hdr + ssl->in_left, len,
1925 ssl->conf->read_timeout );
1926 }
1927 else
1928 {
1929 ret = ssl->f_recv( ssl->p_bio,
1930 ssl->in_hdr + ssl->in_left, len );
1931 }
1932 }
1933
1934 MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %" MBEDTLS_PRINTF_SIZET
1935 ", nb_want: %" MBEDTLS_PRINTF_SIZET,
1936 ssl->in_left, nb_want ) );
1937 MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_recv(_timeout)", ret );
1938
1939 if( ret == 0 )
1940 return( MBEDTLS_ERR_SSL_CONN_EOF );
1941
1942 if( ret < 0 )
1943 return( ret );
1944
1945 if ( (size_t)ret > len || ( INT_MAX > SIZE_MAX && ret > (int)SIZE_MAX ) )
1946 {
1947 MBEDTLS_SSL_DEBUG_MSG( 1,
1948 ( "f_recv returned %d bytes but only %" MBEDTLS_PRINTF_SIZET " were requested",
1949 ret, len ) );
1950 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
1951 }
1952
1953 ssl->in_left += ret;
1954 }
1955 }
1956
1957 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= fetch input" ) );
1958
1959 return( 0 );
1960 }
1961
1962 /*
1963 * Flush any data not yet written
1964 */
mbedtls_ssl_flush_output(mbedtls_ssl_context * ssl)1965 int mbedtls_ssl_flush_output( mbedtls_ssl_context *ssl )
1966 {
1967 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1968 unsigned char *buf;
1969
1970 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> flush output" ) );
1971
1972 if( ssl->f_send == NULL )
1973 {
1974 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Bad usage of mbedtls_ssl_set_bio() "
1975 "or mbedtls_ssl_set_bio()" ) );
1976 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
1977 }
1978
1979 /* Avoid incrementing counter if data is flushed */
1980 if( ssl->out_left == 0 )
1981 {
1982 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= flush output" ) );
1983 return( 0 );
1984 }
1985
1986 while( ssl->out_left > 0 )
1987 {
1988 MBEDTLS_SSL_DEBUG_MSG( 2, ( "message length: %" MBEDTLS_PRINTF_SIZET
1989 ", out_left: %" MBEDTLS_PRINTF_SIZET,
1990 mbedtls_ssl_out_hdr_len( ssl ) + ssl->out_msglen, ssl->out_left ) );
1991
1992 buf = ssl->out_hdr - ssl->out_left;
1993 ret = ssl->f_send( ssl->p_bio, buf, ssl->out_left );
1994
1995 MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_send", ret );
1996
1997 if( ret <= 0 )
1998 return( ret );
1999
2000 if( (size_t)ret > ssl->out_left || ( INT_MAX > SIZE_MAX && ret > (int)SIZE_MAX ) )
2001 {
2002 MBEDTLS_SSL_DEBUG_MSG( 1,
2003 ( "f_send returned %d bytes but only %" MBEDTLS_PRINTF_SIZET " bytes were sent",
2004 ret, ssl->out_left ) );
2005 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
2006 }
2007
2008 ssl->out_left -= ret;
2009 }
2010
2011 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2012 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
2013 {
2014 ssl->out_hdr = ssl->out_buf;
2015 }
2016 else
2017 #endif
2018 {
2019 ssl->out_hdr = ssl->out_buf + 8;
2020 }
2021 mbedtls_ssl_update_out_pointers( ssl, ssl->transform_out );
2022
2023 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= flush output" ) );
2024
2025 return( 0 );
2026 }
2027
2028 /*
2029 * Functions to handle the DTLS retransmission state machine
2030 */
2031 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2032 /*
2033 * Append current handshake message to current outgoing flight
2034 */
ssl_flight_append(mbedtls_ssl_context * ssl)2035 static int ssl_flight_append( mbedtls_ssl_context *ssl )
2036 {
2037 mbedtls_ssl_flight_item *msg;
2038 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_flight_append" ) );
2039 MBEDTLS_SSL_DEBUG_BUF( 4, "message appended to flight",
2040 ssl->out_msg, ssl->out_msglen );
2041
2042 /* Allocate space for current message */
2043 if( ( msg = mbedtls_calloc( 1, sizeof( mbedtls_ssl_flight_item ) ) ) == NULL )
2044 {
2045 MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc %" MBEDTLS_PRINTF_SIZET " bytes failed",
2046 sizeof( mbedtls_ssl_flight_item ) ) );
2047 return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
2048 }
2049
2050 if( ( msg->p = mbedtls_calloc( 1, ssl->out_msglen ) ) == NULL )
2051 {
2052 MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc %" MBEDTLS_PRINTF_SIZET " bytes failed",
2053 ssl->out_msglen ) );
2054 mbedtls_free( msg );
2055 return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
2056 }
2057
2058 /* Copy current handshake message with headers */
2059 memcpy( msg->p, ssl->out_msg, ssl->out_msglen );
2060 msg->len = ssl->out_msglen;
2061 msg->type = ssl->out_msgtype;
2062 msg->next = NULL;
2063
2064 /* Append to the current flight */
2065 if( ssl->handshake->flight == NULL )
2066 ssl->handshake->flight = msg;
2067 else
2068 {
2069 mbedtls_ssl_flight_item *cur = ssl->handshake->flight;
2070 while( cur->next != NULL )
2071 cur = cur->next;
2072 cur->next = msg;
2073 }
2074
2075 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_flight_append" ) );
2076 return( 0 );
2077 }
2078
2079 /*
2080 * Free the current flight of handshake messages
2081 */
mbedtls_ssl_flight_free(mbedtls_ssl_flight_item * flight)2082 void mbedtls_ssl_flight_free( mbedtls_ssl_flight_item *flight )
2083 {
2084 mbedtls_ssl_flight_item *cur = flight;
2085 mbedtls_ssl_flight_item *next;
2086
2087 while( cur != NULL )
2088 {
2089 next = cur->next;
2090
2091 mbedtls_free( cur->p );
2092 mbedtls_free( cur );
2093
2094 cur = next;
2095 }
2096 }
2097
2098 /*
2099 * Swap transform_out and out_ctr with the alternative ones
2100 */
ssl_swap_epochs(mbedtls_ssl_context * ssl)2101 static int ssl_swap_epochs( mbedtls_ssl_context *ssl )
2102 {
2103 mbedtls_ssl_transform *tmp_transform;
2104 unsigned char tmp_out_ctr[MBEDTLS_SSL_SEQUENCE_NUMBER_LEN];
2105
2106 if( ssl->transform_out == ssl->handshake->alt_transform_out )
2107 {
2108 MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip swap epochs" ) );
2109 return( 0 );
2110 }
2111
2112 MBEDTLS_SSL_DEBUG_MSG( 3, ( "swap epochs" ) );
2113
2114 /* Swap transforms */
2115 tmp_transform = ssl->transform_out;
2116 ssl->transform_out = ssl->handshake->alt_transform_out;
2117 ssl->handshake->alt_transform_out = tmp_transform;
2118
2119 /* Swap epoch + sequence_number */
2120 memcpy( tmp_out_ctr, ssl->cur_out_ctr, sizeof( tmp_out_ctr ) );
2121 memcpy( ssl->cur_out_ctr, ssl->handshake->alt_out_ctr,
2122 sizeof( ssl->cur_out_ctr ) );
2123 memcpy( ssl->handshake->alt_out_ctr, tmp_out_ctr,
2124 sizeof( ssl->handshake->alt_out_ctr ) );
2125
2126 /* Adjust to the newly activated transform */
2127 mbedtls_ssl_update_out_pointers( ssl, ssl->transform_out );
2128
2129 return( 0 );
2130 }
2131
2132 /*
2133 * Retransmit the current flight of messages.
2134 */
mbedtls_ssl_resend(mbedtls_ssl_context * ssl)2135 int mbedtls_ssl_resend( mbedtls_ssl_context *ssl )
2136 {
2137 int ret = 0;
2138
2139 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_resend" ) );
2140
2141 ret = mbedtls_ssl_flight_transmit( ssl );
2142
2143 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= mbedtls_ssl_resend" ) );
2144
2145 return( ret );
2146 }
2147
2148 /*
2149 * Transmit or retransmit the current flight of messages.
2150 *
2151 * Need to remember the current message in case flush_output returns
2152 * WANT_WRITE, causing us to exit this function and come back later.
2153 * This function must be called until state is no longer SENDING.
2154 */
mbedtls_ssl_flight_transmit(mbedtls_ssl_context * ssl)2155 int mbedtls_ssl_flight_transmit( mbedtls_ssl_context *ssl )
2156 {
2157 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2158 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_flight_transmit" ) );
2159
2160 if( ssl->handshake->retransmit_state != MBEDTLS_SSL_RETRANS_SENDING )
2161 {
2162 MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialise flight transmission" ) );
2163
2164 ssl->handshake->cur_msg = ssl->handshake->flight;
2165 ssl->handshake->cur_msg_p = ssl->handshake->flight->p + 12;
2166 ret = ssl_swap_epochs( ssl );
2167 if( ret != 0 )
2168 return( ret );
2169
2170 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_SENDING;
2171 }
2172
2173 while( ssl->handshake->cur_msg != NULL )
2174 {
2175 size_t max_frag_len;
2176 const mbedtls_ssl_flight_item * const cur = ssl->handshake->cur_msg;
2177
2178 int const is_finished =
2179 ( cur->type == MBEDTLS_SSL_MSG_HANDSHAKE &&
2180 cur->p[0] == MBEDTLS_SSL_HS_FINISHED );
2181
2182 uint8_t const force_flush = ssl->disable_datagram_packing == 1 ?
2183 SSL_FORCE_FLUSH : SSL_DONT_FORCE_FLUSH;
2184
2185 /* Swap epochs before sending Finished: we can't do it after
2186 * sending ChangeCipherSpec, in case write returns WANT_READ.
2187 * Must be done before copying, may change out_msg pointer */
2188 if( is_finished && ssl->handshake->cur_msg_p == ( cur->p + 12 ) )
2189 {
2190 MBEDTLS_SSL_DEBUG_MSG( 2, ( "swap epochs to send finished message" ) );
2191 ret = ssl_swap_epochs( ssl );
2192 if( ret != 0 )
2193 return( ret );
2194 }
2195
2196 ret = ssl_get_remaining_payload_in_datagram( ssl );
2197 if( ret < 0 )
2198 return( ret );
2199 max_frag_len = (size_t) ret;
2200
2201 /* CCS is copied as is, while HS messages may need fragmentation */
2202 if( cur->type == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
2203 {
2204 if( max_frag_len == 0 )
2205 {
2206 if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
2207 return( ret );
2208
2209 continue;
2210 }
2211
2212 memcpy( ssl->out_msg, cur->p, cur->len );
2213 ssl->out_msglen = cur->len;
2214 ssl->out_msgtype = cur->type;
2215
2216 /* Update position inside current message */
2217 ssl->handshake->cur_msg_p += cur->len;
2218 }
2219 else
2220 {
2221 const unsigned char * const p = ssl->handshake->cur_msg_p;
2222 const size_t hs_len = cur->len - 12;
2223 const size_t frag_off = p - ( cur->p + 12 );
2224 const size_t rem_len = hs_len - frag_off;
2225 size_t cur_hs_frag_len, max_hs_frag_len;
2226
2227 if( ( max_frag_len < 12 ) || ( max_frag_len == 12 && hs_len != 0 ) )
2228 {
2229 if( is_finished )
2230 {
2231 ret = ssl_swap_epochs( ssl );
2232 if( ret != 0 )
2233 return( ret );
2234 }
2235
2236 if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
2237 return( ret );
2238
2239 continue;
2240 }
2241 max_hs_frag_len = max_frag_len - 12;
2242
2243 cur_hs_frag_len = rem_len > max_hs_frag_len ?
2244 max_hs_frag_len : rem_len;
2245
2246 if( frag_off == 0 && cur_hs_frag_len != hs_len )
2247 {
2248 MBEDTLS_SSL_DEBUG_MSG( 2, ( "fragmenting handshake message (%u > %u)",
2249 (unsigned) cur_hs_frag_len,
2250 (unsigned) max_hs_frag_len ) );
2251 }
2252
2253 /* Messages are stored with handshake headers as if not fragmented,
2254 * copy beginning of headers then fill fragmentation fields.
2255 * Handshake headers: type(1) len(3) seq(2) f_off(3) f_len(3) */
2256 memcpy( ssl->out_msg, cur->p, 6 );
2257
2258 ssl->out_msg[6] = MBEDTLS_BYTE_2( frag_off );
2259 ssl->out_msg[7] = MBEDTLS_BYTE_1( frag_off );
2260 ssl->out_msg[8] = MBEDTLS_BYTE_0( frag_off );
2261
2262 ssl->out_msg[ 9] = MBEDTLS_BYTE_2( cur_hs_frag_len );
2263 ssl->out_msg[10] = MBEDTLS_BYTE_1( cur_hs_frag_len );
2264 ssl->out_msg[11] = MBEDTLS_BYTE_0( cur_hs_frag_len );
2265
2266 MBEDTLS_SSL_DEBUG_BUF( 3, "handshake header", ssl->out_msg, 12 );
2267
2268 /* Copy the handshake message content and set records fields */
2269 memcpy( ssl->out_msg + 12, p, cur_hs_frag_len );
2270 ssl->out_msglen = cur_hs_frag_len + 12;
2271 ssl->out_msgtype = cur->type;
2272
2273 /* Update position inside current message */
2274 ssl->handshake->cur_msg_p += cur_hs_frag_len;
2275 }
2276
2277 /* If done with the current message move to the next one if any */
2278 if( ssl->handshake->cur_msg_p >= cur->p + cur->len )
2279 {
2280 if( cur->next != NULL )
2281 {
2282 ssl->handshake->cur_msg = cur->next;
2283 ssl->handshake->cur_msg_p = cur->next->p + 12;
2284 }
2285 else
2286 {
2287 ssl->handshake->cur_msg = NULL;
2288 ssl->handshake->cur_msg_p = NULL;
2289 }
2290 }
2291
2292 /* Actually send the message out */
2293 if( ( ret = mbedtls_ssl_write_record( ssl, force_flush ) ) != 0 )
2294 {
2295 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
2296 return( ret );
2297 }
2298 }
2299
2300 if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
2301 return( ret );
2302
2303 /* Update state and set timer */
2304 if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
2305 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
2306 else
2307 {
2308 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
2309 mbedtls_ssl_set_timer( ssl, ssl->handshake->retransmit_timeout );
2310 }
2311
2312 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= mbedtls_ssl_flight_transmit" ) );
2313
2314 return( 0 );
2315 }
2316
2317 /*
2318 * To be called when the last message of an incoming flight is received.
2319 */
mbedtls_ssl_recv_flight_completed(mbedtls_ssl_context * ssl)2320 void mbedtls_ssl_recv_flight_completed( mbedtls_ssl_context *ssl )
2321 {
2322 /* We won't need to resend that one any more */
2323 mbedtls_ssl_flight_free( ssl->handshake->flight );
2324 ssl->handshake->flight = NULL;
2325 ssl->handshake->cur_msg = NULL;
2326
2327 /* The next incoming flight will start with this msg_seq */
2328 ssl->handshake->in_flight_start_seq = ssl->handshake->in_msg_seq;
2329
2330 /* We don't want to remember CCS's across flight boundaries. */
2331 ssl->handshake->buffering.seen_ccs = 0;
2332
2333 /* Clear future message buffering structure. */
2334 mbedtls_ssl_buffering_free( ssl );
2335
2336 /* Cancel timer */
2337 mbedtls_ssl_set_timer( ssl, 0 );
2338
2339 if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
2340 ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED )
2341 {
2342 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
2343 }
2344 else
2345 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_PREPARING;
2346 }
2347
2348 /*
2349 * To be called when the last message of an outgoing flight is send.
2350 */
mbedtls_ssl_send_flight_completed(mbedtls_ssl_context * ssl)2351 void mbedtls_ssl_send_flight_completed( mbedtls_ssl_context *ssl )
2352 {
2353 ssl_reset_retransmit_timeout( ssl );
2354 mbedtls_ssl_set_timer( ssl, ssl->handshake->retransmit_timeout );
2355
2356 if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
2357 ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED )
2358 {
2359 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
2360 }
2361 else
2362 ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
2363 }
2364 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2365
2366 /*
2367 * Handshake layer functions
2368 */
2369
2370 /*
2371 * Write (DTLS: or queue) current handshake (including CCS) message.
2372 *
2373 * - fill in handshake headers
2374 * - update handshake checksum
2375 * - DTLS: save message for resending
2376 * - then pass to the record layer
2377 *
2378 * DTLS: except for HelloRequest, messages are only queued, and will only be
2379 * actually sent when calling flight_transmit() or resend().
2380 *
2381 * Inputs:
2382 * - ssl->out_msglen: 4 + actual handshake message len
2383 * (4 is the size of handshake headers for TLS)
2384 * - ssl->out_msg[0]: the handshake type (ClientHello, ServerHello, etc)
2385 * - ssl->out_msg + 4: the handshake message body
2386 *
2387 * Outputs, ie state before passing to flight_append() or write_record():
2388 * - ssl->out_msglen: the length of the record contents
2389 * (including handshake headers but excluding record headers)
2390 * - ssl->out_msg: the record contents (handshake headers + content)
2391 */
mbedtls_ssl_write_handshake_msg_ext(mbedtls_ssl_context * ssl,int update_checksum)2392 int mbedtls_ssl_write_handshake_msg_ext( mbedtls_ssl_context *ssl,
2393 int update_checksum )
2394 {
2395 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2396 const size_t hs_len = ssl->out_msglen - 4;
2397 const unsigned char hs_type = ssl->out_msg[0];
2398
2399 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write handshake message" ) );
2400
2401 /*
2402 * Sanity checks
2403 */
2404 if( ssl->out_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE &&
2405 ssl->out_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
2406 {
2407 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
2408 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
2409 }
2410
2411 /* Whenever we send anything different from a
2412 * HelloRequest we should be in a handshake - double check. */
2413 if( ! ( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
2414 hs_type == MBEDTLS_SSL_HS_HELLO_REQUEST ) &&
2415 ssl->handshake == NULL )
2416 {
2417 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
2418 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
2419 }
2420
2421 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2422 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
2423 ssl->handshake != NULL &&
2424 ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
2425 {
2426 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
2427 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
2428 }
2429 #endif
2430
2431 /* Double-check that we did not exceed the bounds
2432 * of the outgoing record buffer.
2433 * This should never fail as the various message
2434 * writing functions must obey the bounds of the
2435 * outgoing record buffer, but better be safe.
2436 *
2437 * Note: We deliberately do not check for the MTU or MFL here.
2438 */
2439 if( ssl->out_msglen > MBEDTLS_SSL_OUT_CONTENT_LEN )
2440 {
2441 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Record too large: "
2442 "size %" MBEDTLS_PRINTF_SIZET
2443 ", maximum %" MBEDTLS_PRINTF_SIZET,
2444 ssl->out_msglen,
2445 (size_t) MBEDTLS_SSL_OUT_CONTENT_LEN ) );
2446 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
2447 }
2448
2449 /*
2450 * Fill handshake headers
2451 */
2452 if( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
2453 {
2454 ssl->out_msg[1] = MBEDTLS_BYTE_2( hs_len );
2455 ssl->out_msg[2] = MBEDTLS_BYTE_1( hs_len );
2456 ssl->out_msg[3] = MBEDTLS_BYTE_0( hs_len );
2457
2458 /*
2459 * DTLS has additional fields in the Handshake layer,
2460 * between the length field and the actual payload:
2461 * uint16 message_seq;
2462 * uint24 fragment_offset;
2463 * uint24 fragment_length;
2464 */
2465 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2466 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
2467 {
2468 /* Make room for the additional DTLS fields */
2469 if( MBEDTLS_SSL_OUT_CONTENT_LEN - ssl->out_msglen < 8 )
2470 {
2471 MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS handshake message too large: "
2472 "size %" MBEDTLS_PRINTF_SIZET ", maximum %" MBEDTLS_PRINTF_SIZET,
2473 hs_len,
2474 (size_t) ( MBEDTLS_SSL_OUT_CONTENT_LEN - 12 ) ) );
2475 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
2476 }
2477
2478 memmove( ssl->out_msg + 12, ssl->out_msg + 4, hs_len );
2479 ssl->out_msglen += 8;
2480
2481 /* Write message_seq and update it, except for HelloRequest */
2482 if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
2483 {
2484 MBEDTLS_PUT_UINT16_BE( ssl->handshake->out_msg_seq, ssl->out_msg, 4 );
2485 ++( ssl->handshake->out_msg_seq );
2486 }
2487 else
2488 {
2489 ssl->out_msg[4] = 0;
2490 ssl->out_msg[5] = 0;
2491 }
2492
2493 /* Handshake hashes are computed without fragmentation,
2494 * so set frag_offset = 0 and frag_len = hs_len for now */
2495 memset( ssl->out_msg + 6, 0x00, 3 );
2496 memcpy( ssl->out_msg + 9, ssl->out_msg + 1, 3 );
2497 }
2498 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2499
2500 /* Update running hashes of handshake messages seen */
2501 if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST && update_checksum != 0 )
2502 ssl->handshake->update_checksum( ssl, ssl->out_msg, ssl->out_msglen );
2503 }
2504
2505 /* Either send now, or just save to be sent (and resent) later */
2506 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2507 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
2508 ! ( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
2509 hs_type == MBEDTLS_SSL_HS_HELLO_REQUEST ) )
2510 {
2511 if( ( ret = ssl_flight_append( ssl ) ) != 0 )
2512 {
2513 MBEDTLS_SSL_DEBUG_RET( 1, "ssl_flight_append", ret );
2514 return( ret );
2515 }
2516 }
2517 else
2518 #endif
2519 {
2520 if( ( ret = mbedtls_ssl_write_record( ssl, SSL_FORCE_FLUSH ) ) != 0 )
2521 {
2522 MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_record", ret );
2523 return( ret );
2524 }
2525 }
2526
2527 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write handshake message" ) );
2528
2529 return( 0 );
2530 }
2531
2532 /*
2533 * Record layer functions
2534 */
2535
2536 /*
2537 * Write current record.
2538 *
2539 * Uses:
2540 * - ssl->out_msgtype: type of the message (AppData, Handshake, Alert, CCS)
2541 * - ssl->out_msglen: length of the record content (excl headers)
2542 * - ssl->out_msg: record content
2543 */
mbedtls_ssl_write_record(mbedtls_ssl_context * ssl,uint8_t force_flush)2544 int mbedtls_ssl_write_record( mbedtls_ssl_context *ssl, uint8_t force_flush )
2545 {
2546 int ret, done = 0;
2547 size_t len = ssl->out_msglen;
2548 uint8_t flush = force_flush;
2549
2550 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write record" ) );
2551
2552 if( !done )
2553 {
2554 unsigned i;
2555 size_t protected_record_size;
2556 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
2557 size_t out_buf_len = ssl->out_buf_len;
2558 #else
2559 size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN;
2560 #endif
2561 /* Skip writing the record content type to after the encryption,
2562 * as it may change when using the CID extension. */
2563 int minor_ver = ssl->minor_ver;
2564 #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
2565 /* TLS 1.3 still uses the TLS 1.2 version identifier
2566 * for backwards compatibility. */
2567 if( minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
2568 minor_ver = MBEDTLS_SSL_MINOR_VERSION_3;
2569 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
2570 mbedtls_ssl_write_version( ssl->major_ver, minor_ver,
2571 ssl->conf->transport, ssl->out_hdr + 1 );
2572
2573 memcpy( ssl->out_ctr, ssl->cur_out_ctr, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN );
2574 MBEDTLS_PUT_UINT16_BE( len, ssl->out_len, 0);
2575
2576 if( ssl->transform_out != NULL )
2577 {
2578 mbedtls_record rec;
2579
2580 rec.buf = ssl->out_iv;
2581 rec.buf_len = out_buf_len - ( ssl->out_iv - ssl->out_buf );
2582 rec.data_len = ssl->out_msglen;
2583 rec.data_offset = ssl->out_msg - rec.buf;
2584
2585 memcpy( &rec.ctr[0], ssl->out_ctr, sizeof( rec.ctr ) );
2586 mbedtls_ssl_write_version( ssl->major_ver, minor_ver,
2587 ssl->conf->transport, rec.ver );
2588 rec.type = ssl->out_msgtype;
2589
2590 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
2591 /* The CID is set by mbedtls_ssl_encrypt_buf(). */
2592 rec.cid_len = 0;
2593 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
2594
2595 if( ( ret = mbedtls_ssl_encrypt_buf( ssl, ssl->transform_out, &rec,
2596 ssl->conf->f_rng, ssl->conf->p_rng ) ) != 0 )
2597 {
2598 MBEDTLS_SSL_DEBUG_RET( 1, "ssl_encrypt_buf", ret );
2599 return( ret );
2600 }
2601
2602 if( rec.data_offset != 0 )
2603 {
2604 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
2605 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
2606 }
2607
2608 /* Update the record content type and CID. */
2609 ssl->out_msgtype = rec.type;
2610 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID )
2611 memcpy( ssl->out_cid, rec.cid, rec.cid_len );
2612 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
2613 ssl->out_msglen = len = rec.data_len;
2614 MBEDTLS_PUT_UINT16_BE( rec.data_len, ssl->out_len, 0 );
2615 }
2616
2617 protected_record_size = len + mbedtls_ssl_out_hdr_len( ssl );
2618
2619 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2620 /* In case of DTLS, double-check that we don't exceed
2621 * the remaining space in the datagram. */
2622 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
2623 {
2624 ret = ssl_get_remaining_space_in_datagram( ssl );
2625 if( ret < 0 )
2626 return( ret );
2627
2628 if( protected_record_size > (size_t) ret )
2629 {
2630 /* Should never happen */
2631 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
2632 }
2633 }
2634 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2635
2636 /* Now write the potentially updated record content type. */
2637 ssl->out_hdr[0] = (unsigned char) ssl->out_msgtype;
2638
2639 MBEDTLS_SSL_DEBUG_MSG( 3, ( "output record: msgtype = %u, "
2640 "version = [%u:%u], msglen = %" MBEDTLS_PRINTF_SIZET,
2641 ssl->out_hdr[0], ssl->out_hdr[1],
2642 ssl->out_hdr[2], len ) );
2643
2644 MBEDTLS_SSL_DEBUG_BUF( 4, "output record sent to network",
2645 ssl->out_hdr, protected_record_size );
2646
2647 ssl->out_left += protected_record_size;
2648 ssl->out_hdr += protected_record_size;
2649 mbedtls_ssl_update_out_pointers( ssl, ssl->transform_out );
2650
2651 for( i = 8; i > mbedtls_ssl_ep_len( ssl ); i-- )
2652 if( ++ssl->cur_out_ctr[i - 1] != 0 )
2653 break;
2654
2655 /* The loop goes to its end iff the counter is wrapping */
2656 if( i == mbedtls_ssl_ep_len( ssl ) )
2657 {
2658 MBEDTLS_SSL_DEBUG_MSG( 1, ( "outgoing message counter would wrap" ) );
2659 return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
2660 }
2661 }
2662
2663 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2664 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
2665 flush == SSL_DONT_FORCE_FLUSH )
2666 {
2667 size_t remaining;
2668 ret = ssl_get_remaining_payload_in_datagram( ssl );
2669 if( ret < 0 )
2670 {
2671 MBEDTLS_SSL_DEBUG_RET( 1, "ssl_get_remaining_payload_in_datagram",
2672 ret );
2673 return( ret );
2674 }
2675
2676 remaining = (size_t) ret;
2677 if( remaining == 0 )
2678 {
2679 flush = SSL_FORCE_FLUSH;
2680 }
2681 else
2682 {
2683 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Still %u bytes available in current datagram", (unsigned) remaining ) );
2684 }
2685 }
2686 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2687
2688 if( ( flush == SSL_FORCE_FLUSH ) &&
2689 ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
2690 {
2691 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flush_output", ret );
2692 return( ret );
2693 }
2694
2695 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write record" ) );
2696
2697 return( 0 );
2698 }
2699
2700 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2701
ssl_hs_is_proper_fragment(mbedtls_ssl_context * ssl)2702 static int ssl_hs_is_proper_fragment( mbedtls_ssl_context *ssl )
2703 {
2704 if( ssl->in_msglen < ssl->in_hslen ||
2705 memcmp( ssl->in_msg + 6, "\0\0\0", 3 ) != 0 ||
2706 memcmp( ssl->in_msg + 9, ssl->in_msg + 1, 3 ) != 0 )
2707 {
2708 return( 1 );
2709 }
2710 return( 0 );
2711 }
2712
ssl_get_hs_frag_len(mbedtls_ssl_context const * ssl)2713 static uint32_t ssl_get_hs_frag_len( mbedtls_ssl_context const *ssl )
2714 {
2715 return( ( ssl->in_msg[9] << 16 ) |
2716 ( ssl->in_msg[10] << 8 ) |
2717 ssl->in_msg[11] );
2718 }
2719
ssl_get_hs_frag_off(mbedtls_ssl_context const * ssl)2720 static uint32_t ssl_get_hs_frag_off( mbedtls_ssl_context const *ssl )
2721 {
2722 return( ( ssl->in_msg[6] << 16 ) |
2723 ( ssl->in_msg[7] << 8 ) |
2724 ssl->in_msg[8] );
2725 }
2726
ssl_check_hs_header(mbedtls_ssl_context const * ssl)2727 static int ssl_check_hs_header( mbedtls_ssl_context const *ssl )
2728 {
2729 uint32_t msg_len, frag_off, frag_len;
2730
2731 msg_len = ssl_get_hs_total_len( ssl );
2732 frag_off = ssl_get_hs_frag_off( ssl );
2733 frag_len = ssl_get_hs_frag_len( ssl );
2734
2735 if( frag_off > msg_len )
2736 return( -1 );
2737
2738 if( frag_len > msg_len - frag_off )
2739 return( -1 );
2740
2741 if( frag_len + 12 > ssl->in_msglen )
2742 return( -1 );
2743
2744 return( 0 );
2745 }
2746
2747 /*
2748 * Mark bits in bitmask (used for DTLS HS reassembly)
2749 */
ssl_bitmask_set(unsigned char * mask,size_t offset,size_t len)2750 static void ssl_bitmask_set( unsigned char *mask, size_t offset, size_t len )
2751 {
2752 unsigned int start_bits, end_bits;
2753
2754 start_bits = 8 - ( offset % 8 );
2755 if( start_bits != 8 )
2756 {
2757 size_t first_byte_idx = offset / 8;
2758
2759 /* Special case */
2760 if( len <= start_bits )
2761 {
2762 for( ; len != 0; len-- )
2763 mask[first_byte_idx] |= 1 << ( start_bits - len );
2764
2765 /* Avoid potential issues with offset or len becoming invalid */
2766 return;
2767 }
2768
2769 offset += start_bits; /* Now offset % 8 == 0 */
2770 len -= start_bits;
2771
2772 for( ; start_bits != 0; start_bits-- )
2773 mask[first_byte_idx] |= 1 << ( start_bits - 1 );
2774 }
2775
2776 end_bits = len % 8;
2777 if( end_bits != 0 )
2778 {
2779 size_t last_byte_idx = ( offset + len ) / 8;
2780
2781 len -= end_bits; /* Now len % 8 == 0 */
2782
2783 for( ; end_bits != 0; end_bits-- )
2784 mask[last_byte_idx] |= 1 << ( 8 - end_bits );
2785 }
2786
2787 memset( mask + offset / 8, 0xFF, len / 8 );
2788 }
2789
2790 /*
2791 * Check that bitmask is full
2792 */
ssl_bitmask_check(unsigned char * mask,size_t len)2793 static int ssl_bitmask_check( unsigned char *mask, size_t len )
2794 {
2795 size_t i;
2796
2797 for( i = 0; i < len / 8; i++ )
2798 if( mask[i] != 0xFF )
2799 return( -1 );
2800
2801 for( i = 0; i < len % 8; i++ )
2802 if( ( mask[len / 8] & ( 1 << ( 7 - i ) ) ) == 0 )
2803 return( -1 );
2804
2805 return( 0 );
2806 }
2807
2808 /* msg_len does not include the handshake header */
ssl_get_reassembly_buffer_size(size_t msg_len,unsigned add_bitmap)2809 static size_t ssl_get_reassembly_buffer_size( size_t msg_len,
2810 unsigned add_bitmap )
2811 {
2812 size_t alloc_len;
2813
2814 alloc_len = 12; /* Handshake header */
2815 alloc_len += msg_len; /* Content buffer */
2816
2817 if( add_bitmap )
2818 alloc_len += msg_len / 8 + ( msg_len % 8 != 0 ); /* Bitmap */
2819
2820 return( alloc_len );
2821 }
2822
2823 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2824
ssl_get_hs_total_len(mbedtls_ssl_context const * ssl)2825 static uint32_t ssl_get_hs_total_len( mbedtls_ssl_context const *ssl )
2826 {
2827 return( ( ssl->in_msg[1] << 16 ) |
2828 ( ssl->in_msg[2] << 8 ) |
2829 ssl->in_msg[3] );
2830 }
2831
mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context * ssl)2832 int mbedtls_ssl_prepare_handshake_record( mbedtls_ssl_context *ssl )
2833 {
2834 if( ssl->in_msglen < mbedtls_ssl_hs_hdr_len( ssl ) )
2835 {
2836 MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake message too short: %" MBEDTLS_PRINTF_SIZET,
2837 ssl->in_msglen ) );
2838 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
2839 }
2840
2841 ssl->in_hslen = mbedtls_ssl_hs_hdr_len( ssl ) + ssl_get_hs_total_len( ssl );
2842
2843 MBEDTLS_SSL_DEBUG_MSG( 3, ( "handshake message: msglen ="
2844 " %" MBEDTLS_PRINTF_SIZET ", type = %u, hslen = %" MBEDTLS_PRINTF_SIZET,
2845 ssl->in_msglen, ssl->in_msg[0], ssl->in_hslen ) );
2846
2847 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2848 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
2849 {
2850 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2851 unsigned int recv_msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
2852
2853 if( ssl_check_hs_header( ssl ) != 0 )
2854 {
2855 MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid handshake header" ) );
2856 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
2857 }
2858
2859 if( ssl->handshake != NULL &&
2860 ( ( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER &&
2861 recv_msg_seq != ssl->handshake->in_msg_seq ) ||
2862 ( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER &&
2863 ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO ) ) )
2864 {
2865 if( recv_msg_seq > ssl->handshake->in_msg_seq )
2866 {
2867 MBEDTLS_SSL_DEBUG_MSG( 2, ( "received future handshake message of sequence number %u (next %u)",
2868 recv_msg_seq,
2869 ssl->handshake->in_msg_seq ) );
2870 return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
2871 }
2872
2873 /* Retransmit only on last message from previous flight, to avoid
2874 * too many retransmissions.
2875 * Besides, No sane server ever retransmits HelloVerifyRequest */
2876 if( recv_msg_seq == ssl->handshake->in_flight_start_seq - 1 &&
2877 ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST )
2878 {
2879 MBEDTLS_SSL_DEBUG_MSG( 2, ( "received message from last flight, "
2880 "message_seq = %u, start_of_flight = %u",
2881 recv_msg_seq,
2882 ssl->handshake->in_flight_start_seq ) );
2883
2884 if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
2885 {
2886 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend", ret );
2887 return( ret );
2888 }
2889 }
2890 else
2891 {
2892 MBEDTLS_SSL_DEBUG_MSG( 2, ( "dropping out-of-sequence message: "
2893 "message_seq = %u, expected = %u",
2894 recv_msg_seq,
2895 ssl->handshake->in_msg_seq ) );
2896 }
2897
2898 return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
2899 }
2900 /* Wait until message completion to increment in_msg_seq */
2901
2902 /* Message reassembly is handled alongside buffering of future
2903 * messages; the commonality is that both handshake fragments and
2904 * future messages cannot be forwarded immediately to the
2905 * handshake logic layer. */
2906 if( ssl_hs_is_proper_fragment( ssl ) == 1 )
2907 {
2908 MBEDTLS_SSL_DEBUG_MSG( 2, ( "found fragmented DTLS handshake message" ) );
2909 return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
2910 }
2911 }
2912 else
2913 #endif /* MBEDTLS_SSL_PROTO_DTLS */
2914 /* With TLS we don't handle fragmentation (for now) */
2915 if( ssl->in_msglen < ssl->in_hslen )
2916 {
2917 MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS handshake fragmentation not supported" ) );
2918 return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
2919 }
2920
2921 return( 0 );
2922 }
2923
mbedtls_ssl_update_handshake_status(mbedtls_ssl_context * ssl)2924 void mbedtls_ssl_update_handshake_status( mbedtls_ssl_context *ssl )
2925 {
2926 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
2927
2928 if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER && hs != NULL )
2929 {
2930 ssl->handshake->update_checksum( ssl, ssl->in_msg, ssl->in_hslen );
2931 }
2932
2933 /* Handshake message is complete, increment counter */
2934 #if defined(MBEDTLS_SSL_PROTO_DTLS)
2935 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
2936 ssl->handshake != NULL )
2937 {
2938 unsigned offset;
2939 mbedtls_ssl_hs_buffer *hs_buf;
2940
2941 /* Increment handshake sequence number */
2942 hs->in_msg_seq++;
2943
2944 /*
2945 * Clear up handshake buffering and reassembly structure.
2946 */
2947
2948 /* Free first entry */
2949 ssl_buffering_free_slot( ssl, 0 );
2950
2951 /* Shift all other entries */
2952 for( offset = 0, hs_buf = &hs->buffering.hs[0];
2953 offset + 1 < MBEDTLS_SSL_MAX_BUFFERED_HS;
2954 offset++, hs_buf++ )
2955 {
2956 *hs_buf = *(hs_buf + 1);
2957 }
2958
2959 /* Create a fresh last entry */
2960 memset( hs_buf, 0, sizeof( mbedtls_ssl_hs_buffer ) );
2961 }
2962 #endif
2963 }
2964
2965 /*
2966 * DTLS anti-replay: RFC 6347 4.1.2.6
2967 *
2968 * in_window is a field of bits numbered from 0 (lsb) to 63 (msb).
2969 * Bit n is set iff record number in_window_top - n has been seen.
2970 *
2971 * Usually, in_window_top is the last record number seen and the lsb of
2972 * in_window is set. The only exception is the initial state (record number 0
2973 * not seen yet).
2974 */
2975 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
mbedtls_ssl_dtls_replay_reset(mbedtls_ssl_context * ssl)2976 void mbedtls_ssl_dtls_replay_reset( mbedtls_ssl_context *ssl )
2977 {
2978 ssl->in_window_top = 0;
2979 ssl->in_window = 0;
2980 }
2981
ssl_load_six_bytes(unsigned char * buf)2982 static inline uint64_t ssl_load_six_bytes( unsigned char *buf )
2983 {
2984 return( ( (uint64_t) buf[0] << 40 ) |
2985 ( (uint64_t) buf[1] << 32 ) |
2986 ( (uint64_t) buf[2] << 24 ) |
2987 ( (uint64_t) buf[3] << 16 ) |
2988 ( (uint64_t) buf[4] << 8 ) |
2989 ( (uint64_t) buf[5] ) );
2990 }
2991
mbedtls_ssl_dtls_record_replay_check(mbedtls_ssl_context * ssl,uint8_t * record_in_ctr)2992 static int mbedtls_ssl_dtls_record_replay_check( mbedtls_ssl_context *ssl, uint8_t *record_in_ctr )
2993 {
2994 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2995 unsigned char *original_in_ctr;
2996
2997 // save original in_ctr
2998 original_in_ctr = ssl->in_ctr;
2999
3000 // use counter from record
3001 ssl->in_ctr = record_in_ctr;
3002
3003 ret = mbedtls_ssl_dtls_replay_check( (mbedtls_ssl_context const *) ssl );
3004
3005 // restore the counter
3006 ssl->in_ctr = original_in_ctr;
3007
3008 return ret;
3009 }
3010
3011 /*
3012 * Return 0 if sequence number is acceptable, -1 otherwise
3013 */
mbedtls_ssl_dtls_replay_check(mbedtls_ssl_context const * ssl)3014 int mbedtls_ssl_dtls_replay_check( mbedtls_ssl_context const *ssl )
3015 {
3016 uint64_t rec_seqnum = ssl_load_six_bytes( ssl->in_ctr + 2 );
3017 uint64_t bit;
3018
3019 if( ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED )
3020 return( 0 );
3021
3022 if( rec_seqnum > ssl->in_window_top )
3023 return( 0 );
3024
3025 bit = ssl->in_window_top - rec_seqnum;
3026
3027 if( bit >= 64 )
3028 return( -1 );
3029
3030 if( ( ssl->in_window & ( (uint64_t) 1 << bit ) ) != 0 )
3031 return( -1 );
3032
3033 return( 0 );
3034 }
3035
3036 /*
3037 * Update replay window on new validated record
3038 */
mbedtls_ssl_dtls_replay_update(mbedtls_ssl_context * ssl)3039 void mbedtls_ssl_dtls_replay_update( mbedtls_ssl_context *ssl )
3040 {
3041 uint64_t rec_seqnum = ssl_load_six_bytes( ssl->in_ctr + 2 );
3042
3043 if( ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED )
3044 return;
3045
3046 if( rec_seqnum > ssl->in_window_top )
3047 {
3048 /* Update window_top and the contents of the window */
3049 uint64_t shift = rec_seqnum - ssl->in_window_top;
3050
3051 if( shift >= 64 )
3052 ssl->in_window = 1;
3053 else
3054 {
3055 ssl->in_window <<= shift;
3056 ssl->in_window |= 1;
3057 }
3058
3059 ssl->in_window_top = rec_seqnum;
3060 }
3061 else
3062 {
3063 /* Mark that number as seen in the current window */
3064 uint64_t bit = ssl->in_window_top - rec_seqnum;
3065
3066 if( bit < 64 ) /* Always true, but be extra sure */
3067 ssl->in_window |= (uint64_t) 1 << bit;
3068 }
3069 }
3070 #endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
3071
3072 #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
3073 /*
3074 * Without any SSL context, check if a datagram looks like a ClientHello with
3075 * a valid cookie, and if it doesn't, generate a HelloVerifyRequest message.
3076 * Both input and output include full DTLS headers.
3077 *
3078 * - if cookie is valid, return 0
3079 * - if ClientHello looks superficially valid but cookie is not,
3080 * fill obuf and set olen, then
3081 * return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED
3082 * - otherwise return a specific error code
3083 */
ssl_check_dtls_clihlo_cookie(mbedtls_ssl_cookie_write_t * f_cookie_write,mbedtls_ssl_cookie_check_t * f_cookie_check,void * p_cookie,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)3084 static int ssl_check_dtls_clihlo_cookie(
3085 mbedtls_ssl_cookie_write_t *f_cookie_write,
3086 mbedtls_ssl_cookie_check_t *f_cookie_check,
3087 void *p_cookie,
3088 const unsigned char *cli_id, size_t cli_id_len,
3089 const unsigned char *in, size_t in_len,
3090 unsigned char *obuf, size_t buf_len, size_t *olen )
3091 {
3092 size_t sid_len, cookie_len;
3093 unsigned char *p;
3094
3095 /*
3096 * Structure of ClientHello with record and handshake headers,
3097 * and expected values. We don't need to check a lot, more checks will be
3098 * done when actually parsing the ClientHello - skipping those checks
3099 * avoids code duplication and does not make cookie forging any easier.
3100 *
3101 * 0-0 ContentType type; copied, must be handshake
3102 * 1-2 ProtocolVersion version; copied
3103 * 3-4 uint16 epoch; copied, must be 0
3104 * 5-10 uint48 sequence_number; copied
3105 * 11-12 uint16 length; (ignored)
3106 *
3107 * 13-13 HandshakeType msg_type; (ignored)
3108 * 14-16 uint24 length; (ignored)
3109 * 17-18 uint16 message_seq; copied
3110 * 19-21 uint24 fragment_offset; copied, must be 0
3111 * 22-24 uint24 fragment_length; (ignored)
3112 *
3113 * 25-26 ProtocolVersion client_version; (ignored)
3114 * 27-58 Random random; (ignored)
3115 * 59-xx SessionID session_id; 1 byte len + sid_len content
3116 * 60+ opaque cookie<0..2^8-1>; 1 byte len + content
3117 * ...
3118 *
3119 * Minimum length is 61 bytes.
3120 */
3121 if( in_len < 61 ||
3122 in[0] != MBEDTLS_SSL_MSG_HANDSHAKE ||
3123 in[3] != 0 || in[4] != 0 ||
3124 in[19] != 0 || in[20] != 0 || in[21] != 0 )
3125 {
3126 return( MBEDTLS_ERR_SSL_DECODE_ERROR );
3127 }
3128
3129 sid_len = in[59];
3130 if( sid_len > in_len - 61 )
3131 return( MBEDTLS_ERR_SSL_DECODE_ERROR );
3132
3133 cookie_len = in[60 + sid_len];
3134 if( cookie_len > in_len - 60 )
3135 return( MBEDTLS_ERR_SSL_DECODE_ERROR );
3136
3137 if( f_cookie_check( p_cookie, in + sid_len + 61, cookie_len,
3138 cli_id, cli_id_len ) == 0 )
3139 {
3140 /* Valid cookie */
3141 return( 0 );
3142 }
3143
3144 /*
3145 * If we get here, we've got an invalid cookie, let's prepare HVR.
3146 *
3147 * 0-0 ContentType type; copied
3148 * 1-2 ProtocolVersion version; copied
3149 * 3-4 uint16 epoch; copied
3150 * 5-10 uint48 sequence_number; copied
3151 * 11-12 uint16 length; olen - 13
3152 *
3153 * 13-13 HandshakeType msg_type; hello_verify_request
3154 * 14-16 uint24 length; olen - 25
3155 * 17-18 uint16 message_seq; copied
3156 * 19-21 uint24 fragment_offset; copied
3157 * 22-24 uint24 fragment_length; olen - 25
3158 *
3159 * 25-26 ProtocolVersion server_version; 0xfe 0xff
3160 * 27-27 opaque cookie<0..2^8-1>; cookie_len = olen - 27, cookie
3161 *
3162 * Minimum length is 28.
3163 */
3164 if( buf_len < 28 )
3165 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
3166
3167 /* Copy most fields and adapt others */
3168 memcpy( obuf, in, 25 );
3169 obuf[13] = MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST;
3170 obuf[25] = 0xfe;
3171 obuf[26] = 0xff;
3172
3173 /* Generate and write actual cookie */
3174 p = obuf + 28;
3175 if( f_cookie_write( p_cookie,
3176 &p, obuf + buf_len, cli_id, cli_id_len ) != 0 )
3177 {
3178 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
3179 }
3180
3181 *olen = p - obuf;
3182
3183 /* Go back and fill length fields */
3184 obuf[27] = (unsigned char)( *olen - 28 );
3185
3186 obuf[14] = obuf[22] = MBEDTLS_BYTE_2( *olen - 25 );
3187 obuf[15] = obuf[23] = MBEDTLS_BYTE_1( *olen - 25 );
3188 obuf[16] = obuf[24] = MBEDTLS_BYTE_0( *olen - 25 );
3189
3190 MBEDTLS_PUT_UINT16_BE( *olen - 13, obuf, 11 );
3191
3192 return( MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED );
3193 }
3194
3195 /*
3196 * Handle possible client reconnect with the same UDP quadruplet
3197 * (RFC 6347 Section 4.2.8).
3198 *
3199 * Called by ssl_parse_record_header() in case we receive an epoch 0 record
3200 * that looks like a ClientHello.
3201 *
3202 * - if the input looks like a ClientHello without cookies,
3203 * send back HelloVerifyRequest, then return 0
3204 * - if the input looks like a ClientHello with a valid cookie,
3205 * reset the session of the current context, and
3206 * return MBEDTLS_ERR_SSL_CLIENT_RECONNECT
3207 * - if anything goes wrong, return a specific error code
3208 *
3209 * This function is called (through ssl_check_client_reconnect()) when an
3210 * unexpected record is found in ssl_get_next_record(), which will discard the
3211 * record if we return 0, and bubble up the return value otherwise (this
3212 * includes the case of MBEDTLS_ERR_SSL_CLIENT_RECONNECT and of unexpected
3213 * errors, and is the right thing to do in both cases).
3214 */
ssl_handle_possible_reconnect(mbedtls_ssl_context * ssl)3215 static int ssl_handle_possible_reconnect( mbedtls_ssl_context *ssl )
3216 {
3217 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
3218 size_t len;
3219
3220 if( ssl->conf->f_cookie_write == NULL ||
3221 ssl->conf->f_cookie_check == NULL )
3222 {
3223 /* If we can't use cookies to verify reachability of the peer,
3224 * drop the record. */
3225 MBEDTLS_SSL_DEBUG_MSG( 1, ( "no cookie callbacks, "
3226 "can't check reconnect validity" ) );
3227 return( 0 );
3228 }
3229
3230 ret = ssl_check_dtls_clihlo_cookie(
3231 ssl->conf->f_cookie_write,
3232 ssl->conf->f_cookie_check,
3233 ssl->conf->p_cookie,
3234 ssl->cli_id, ssl->cli_id_len,
3235 ssl->in_buf, ssl->in_left,
3236 ssl->out_buf, MBEDTLS_SSL_OUT_CONTENT_LEN, &len );
3237
3238 MBEDTLS_SSL_DEBUG_RET( 2, "ssl_check_dtls_clihlo_cookie", ret );
3239
3240 if( ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED )
3241 {
3242 int send_ret;
3243 MBEDTLS_SSL_DEBUG_MSG( 1, ( "sending HelloVerifyRequest" ) );
3244 MBEDTLS_SSL_DEBUG_BUF( 4, "output record sent to network",
3245 ssl->out_buf, len );
3246 /* Don't check write errors as we can't do anything here.
3247 * If the error is permanent we'll catch it later,
3248 * if it's not, then hopefully it'll work next time. */
3249 send_ret = ssl->f_send( ssl->p_bio, ssl->out_buf, len );
3250 MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_send", send_ret );
3251 (void) send_ret;
3252
3253 return( 0 );
3254 }
3255
3256 if( ret == 0 )
3257 {
3258 MBEDTLS_SSL_DEBUG_MSG( 1, ( "cookie is valid, resetting context" ) );
3259 if( ( ret = mbedtls_ssl_session_reset_int( ssl, 1 ) ) != 0 )
3260 {
3261 MBEDTLS_SSL_DEBUG_RET( 1, "reset", ret );
3262 return( ret );
3263 }
3264
3265 return( MBEDTLS_ERR_SSL_CLIENT_RECONNECT );
3266 }
3267
3268 return( ret );
3269 }
3270 #endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
3271
ssl_check_record_type(uint8_t record_type)3272 static int ssl_check_record_type( uint8_t record_type )
3273 {
3274 if( record_type != MBEDTLS_SSL_MSG_HANDSHAKE &&
3275 record_type != MBEDTLS_SSL_MSG_ALERT &&
3276 record_type != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC &&
3277 record_type != MBEDTLS_SSL_MSG_APPLICATION_DATA )
3278 {
3279 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3280 }
3281
3282 return( 0 );
3283 }
3284
3285 /*
3286 * ContentType type;
3287 * ProtocolVersion version;
3288 * uint16 epoch; // DTLS only
3289 * uint48 sequence_number; // DTLS only
3290 * uint16 length;
3291 *
3292 * Return 0 if header looks sane (and, for DTLS, the record is expected)
3293 * MBEDTLS_ERR_SSL_INVALID_RECORD if the header looks bad,
3294 * MBEDTLS_ERR_SSL_UNEXPECTED_RECORD (DTLS only) if sane but unexpected.
3295 *
3296 * With DTLS, mbedtls_ssl_read_record() will:
3297 * 1. proceed with the record if this function returns 0
3298 * 2. drop only the current record if this function returns UNEXPECTED_RECORD
3299 * 3. return CLIENT_RECONNECT if this function return that value
3300 * 4. drop the whole datagram if this function returns anything else.
3301 * Point 2 is needed when the peer is resending, and we have already received
3302 * the first record from a datagram but are still waiting for the others.
3303 */
ssl_parse_record_header(mbedtls_ssl_context const * ssl,unsigned char * buf,size_t len,mbedtls_record * rec)3304 static int ssl_parse_record_header( mbedtls_ssl_context const *ssl,
3305 unsigned char *buf,
3306 size_t len,
3307 mbedtls_record *rec )
3308 {
3309 int major_ver, minor_ver;
3310
3311 size_t const rec_hdr_type_offset = 0;
3312 size_t const rec_hdr_type_len = 1;
3313
3314 size_t const rec_hdr_version_offset = rec_hdr_type_offset +
3315 rec_hdr_type_len;
3316 size_t const rec_hdr_version_len = 2;
3317
3318 size_t const rec_hdr_ctr_len = 8;
3319 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3320 uint32_t rec_epoch;
3321 size_t const rec_hdr_ctr_offset = rec_hdr_version_offset +
3322 rec_hdr_version_len;
3323
3324 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
3325 size_t const rec_hdr_cid_offset = rec_hdr_ctr_offset +
3326 rec_hdr_ctr_len;
3327 size_t rec_hdr_cid_len = 0;
3328 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
3329 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3330
3331 size_t rec_hdr_len_offset; /* To be determined */
3332 size_t const rec_hdr_len_len = 2;
3333
3334 /*
3335 * Check minimum lengths for record header.
3336 */
3337
3338 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3339 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
3340 {
3341 rec_hdr_len_offset = rec_hdr_ctr_offset + rec_hdr_ctr_len;
3342 }
3343 else
3344 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3345 {
3346 rec_hdr_len_offset = rec_hdr_version_offset + rec_hdr_version_len;
3347 }
3348
3349 if( len < rec_hdr_len_offset + rec_hdr_len_len )
3350 {
3351 MBEDTLS_SSL_DEBUG_MSG( 1, ( "datagram of length %u too small to hold DTLS record header of length %u",
3352 (unsigned) len,
3353 (unsigned)( rec_hdr_len_len + rec_hdr_len_len ) ) );
3354 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3355 }
3356
3357 /*
3358 * Parse and validate record content type
3359 */
3360
3361 rec->type = buf[ rec_hdr_type_offset ];
3362
3363 /* Check record content type */
3364 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
3365 rec->cid_len = 0;
3366
3367 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
3368 ssl->conf->cid_len != 0 &&
3369 rec->type == MBEDTLS_SSL_MSG_CID )
3370 {
3371 /* Shift pointers to account for record header including CID
3372 * struct {
3373 * ContentType special_type = tls12_cid;
3374 * ProtocolVersion version;
3375 * uint16 epoch;
3376 * uint48 sequence_number;
3377 * opaque cid[cid_length]; // Additional field compared to
3378 * // default DTLS record format
3379 * uint16 length;
3380 * opaque enc_content[DTLSCiphertext.length];
3381 * } DTLSCiphertext;
3382 */
3383
3384 /* So far, we only support static CID lengths
3385 * fixed in the configuration. */
3386 rec_hdr_cid_len = ssl->conf->cid_len;
3387 rec_hdr_len_offset += rec_hdr_cid_len;
3388
3389 if( len < rec_hdr_len_offset + rec_hdr_len_len )
3390 {
3391 MBEDTLS_SSL_DEBUG_MSG( 1, ( "datagram of length %u too small to hold DTLS record header including CID, length %u",
3392 (unsigned) len,
3393 (unsigned)( rec_hdr_len_offset + rec_hdr_len_len ) ) );
3394 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3395 }
3396
3397 /* configured CID len is guaranteed at most 255, see
3398 * MBEDTLS_SSL_CID_OUT_LEN_MAX in check_config.h */
3399 rec->cid_len = (uint8_t) rec_hdr_cid_len;
3400 memcpy( rec->cid, buf + rec_hdr_cid_offset, rec_hdr_cid_len );
3401 }
3402 else
3403 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
3404 {
3405 if( ssl_check_record_type( rec->type ) )
3406 {
3407 MBEDTLS_SSL_DEBUG_MSG( 1, ( "unknown record type %u",
3408 (unsigned) rec->type ) );
3409 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3410 }
3411 }
3412
3413 /*
3414 * Parse and validate record version
3415 */
3416
3417 rec->ver[0] = buf[ rec_hdr_version_offset + 0 ];
3418 rec->ver[1] = buf[ rec_hdr_version_offset + 1 ];
3419 mbedtls_ssl_read_version( &major_ver, &minor_ver,
3420 ssl->conf->transport,
3421 &rec->ver[0] );
3422
3423 if( major_ver != ssl->major_ver )
3424 {
3425 MBEDTLS_SSL_DEBUG_MSG( 1, ( "major version mismatch" ) );
3426 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3427 }
3428
3429 if( minor_ver > ssl->conf->max_minor_ver )
3430 {
3431 MBEDTLS_SSL_DEBUG_MSG( 1, ( "minor version mismatch" ) );
3432 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3433 }
3434
3435 /*
3436 * Parse/Copy record sequence number.
3437 */
3438
3439 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3440 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
3441 {
3442 /* Copy explicit record sequence number from input buffer. */
3443 memcpy( &rec->ctr[0], buf + rec_hdr_ctr_offset,
3444 rec_hdr_ctr_len );
3445 }
3446 else
3447 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3448 {
3449 /* Copy implicit record sequence number from SSL context structure. */
3450 memcpy( &rec->ctr[0], ssl->in_ctr, rec_hdr_ctr_len );
3451 }
3452
3453 /*
3454 * Parse record length.
3455 */
3456
3457 rec->data_offset = rec_hdr_len_offset + rec_hdr_len_len;
3458 rec->data_len = ( (size_t) buf[ rec_hdr_len_offset + 0 ] << 8 ) |
3459 ( (size_t) buf[ rec_hdr_len_offset + 1 ] << 0 );
3460 MBEDTLS_SSL_DEBUG_BUF( 4, "input record header", buf, rec->data_offset );
3461
3462 MBEDTLS_SSL_DEBUG_MSG( 3, ( "input record: msgtype = %u, "
3463 "version = [%d:%d], msglen = %" MBEDTLS_PRINTF_SIZET,
3464 rec->type,
3465 major_ver, minor_ver, rec->data_len ) );
3466
3467 rec->buf = buf;
3468 rec->buf_len = rec->data_offset + rec->data_len;
3469
3470 if( rec->data_len == 0 )
3471 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3472
3473 /*
3474 * DTLS-related tests.
3475 * Check epoch before checking length constraint because
3476 * the latter varies with the epoch. E.g., if a ChangeCipherSpec
3477 * message gets duplicated before the corresponding Finished message,
3478 * the second ChangeCipherSpec should be discarded because it belongs
3479 * to an old epoch, but not because its length is shorter than
3480 * the minimum record length for packets using the new record transform.
3481 * Note that these two kinds of failures are handled differently,
3482 * as an unexpected record is silently skipped but an invalid
3483 * record leads to the entire datagram being dropped.
3484 */
3485 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3486 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
3487 {
3488 rec_epoch = ( rec->ctr[0] << 8 ) | rec->ctr[1];
3489
3490 /* Check that the datagram is large enough to contain a record
3491 * of the advertised length. */
3492 if( len < rec->data_offset + rec->data_len )
3493 {
3494 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Datagram of length %u too small to contain record of advertised length %u.",
3495 (unsigned) len,
3496 (unsigned)( rec->data_offset + rec->data_len ) ) );
3497 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3498 }
3499
3500 /* Records from other, non-matching epochs are silently discarded.
3501 * (The case of same-port Client reconnects must be considered in
3502 * the caller). */
3503 if( rec_epoch != ssl->in_epoch )
3504 {
3505 MBEDTLS_SSL_DEBUG_MSG( 1, ( "record from another epoch: "
3506 "expected %u, received %lu",
3507 ssl->in_epoch, (unsigned long) rec_epoch ) );
3508
3509 /* Records from the next epoch are considered for buffering
3510 * (concretely: early Finished messages). */
3511 if( rec_epoch == (unsigned) ssl->in_epoch + 1 )
3512 {
3513 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Consider record for buffering" ) );
3514 return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
3515 }
3516
3517 return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
3518 }
3519 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
3520 /* For records from the correct epoch, check whether their
3521 * sequence number has been seen before. */
3522 else if( mbedtls_ssl_dtls_record_replay_check( (mbedtls_ssl_context *) ssl,
3523 &rec->ctr[0] ) != 0 )
3524 {
3525 MBEDTLS_SSL_DEBUG_MSG( 1, ( "replayed record" ) );
3526 return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
3527 }
3528 #endif
3529 }
3530 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3531
3532 return( 0 );
3533 }
3534
3535
3536 #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
ssl_check_client_reconnect(mbedtls_ssl_context * ssl)3537 static int ssl_check_client_reconnect( mbedtls_ssl_context *ssl )
3538 {
3539 unsigned int rec_epoch = ( ssl->in_ctr[0] << 8 ) | ssl->in_ctr[1];
3540
3541 /*
3542 * Check for an epoch 0 ClientHello. We can't use in_msg here to
3543 * access the first byte of record content (handshake type), as we
3544 * have an active transform (possibly iv_len != 0), so use the
3545 * fact that the record header len is 13 instead.
3546 */
3547 if( rec_epoch == 0 &&
3548 ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
3549 ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER &&
3550 ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
3551 ssl->in_left > 13 &&
3552 ssl->in_buf[13] == MBEDTLS_SSL_HS_CLIENT_HELLO )
3553 {
3554 MBEDTLS_SSL_DEBUG_MSG( 1, ( "possible client reconnect "
3555 "from the same port" ) );
3556 return( ssl_handle_possible_reconnect( ssl ) );
3557 }
3558
3559 return( 0 );
3560 }
3561 #endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
3562
3563 /*
3564 * If applicable, decrypt record content
3565 */
ssl_prepare_record_content(mbedtls_ssl_context * ssl,mbedtls_record * rec)3566 static int ssl_prepare_record_content( mbedtls_ssl_context *ssl,
3567 mbedtls_record *rec )
3568 {
3569 int ret, done = 0;
3570
3571 MBEDTLS_SSL_DEBUG_BUF( 4, "input record from network",
3572 rec->buf, rec->buf_len );
3573
3574 if( !done && ssl->transform_in != NULL )
3575 {
3576 unsigned char const old_msg_type = rec->type;
3577
3578 if( ( ret = mbedtls_ssl_decrypt_buf( ssl, ssl->transform_in,
3579 rec ) ) != 0 )
3580 {
3581 MBEDTLS_SSL_DEBUG_RET( 1, "ssl_decrypt_buf", ret );
3582
3583 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
3584 if( ret == MBEDTLS_ERR_SSL_UNEXPECTED_CID &&
3585 ssl->conf->ignore_unexpected_cid
3586 == MBEDTLS_SSL_UNEXPECTED_CID_IGNORE )
3587 {
3588 MBEDTLS_SSL_DEBUG_MSG( 3, ( "ignoring unexpected CID" ) );
3589 ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
3590 }
3591 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
3592
3593 return( ret );
3594 }
3595
3596 if( old_msg_type != rec->type )
3597 {
3598 MBEDTLS_SSL_DEBUG_MSG( 4, ( "record type after decrypt (before %d): %d",
3599 old_msg_type, rec->type ) );
3600 }
3601
3602 MBEDTLS_SSL_DEBUG_BUF( 4, "input payload after decrypt",
3603 rec->buf + rec->data_offset, rec->data_len );
3604
3605 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
3606 /* We have already checked the record content type
3607 * in ssl_parse_record_header(), failing or silently
3608 * dropping the record in the case of an unknown type.
3609 *
3610 * Since with the use of CIDs, the record content type
3611 * might change during decryption, re-check the record
3612 * content type, but treat a failure as fatal this time. */
3613 if( ssl_check_record_type( rec->type ) )
3614 {
3615 MBEDTLS_SSL_DEBUG_MSG( 1, ( "unknown record type" ) );
3616 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3617 }
3618 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
3619
3620 if( rec->data_len == 0 )
3621 {
3622 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
3623 if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3
3624 && rec->type != MBEDTLS_SSL_MSG_APPLICATION_DATA )
3625 {
3626 /* TLS v1.2 explicitly disallows zero-length messages which are not application data */
3627 MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid zero-length message type: %d", ssl->in_msgtype ) );
3628 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3629 }
3630 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
3631
3632 ssl->nb_zero++;
3633
3634 /*
3635 * Three or more empty messages may be a DoS attack
3636 * (excessive CPU consumption).
3637 */
3638 if( ssl->nb_zero > 3 )
3639 {
3640 MBEDTLS_SSL_DEBUG_MSG( 1, ( "received four consecutive empty "
3641 "messages, possible DoS attack" ) );
3642 /* Treat the records as if they were not properly authenticated,
3643 * thereby failing the connection if we see more than allowed
3644 * by the configured bad MAC threshold. */
3645 return( MBEDTLS_ERR_SSL_INVALID_MAC );
3646 }
3647 }
3648 else
3649 ssl->nb_zero = 0;
3650
3651 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3652 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
3653 {
3654 ; /* in_ctr read from peer, not maintained internally */
3655 }
3656 else
3657 #endif
3658 {
3659 unsigned i;
3660 for( i = MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
3661 i > mbedtls_ssl_ep_len( ssl ); i-- )
3662 {
3663 if( ++ssl->in_ctr[i - 1] != 0 )
3664 break;
3665 }
3666
3667 /* The loop goes to its end iff the counter is wrapping */
3668 if( i == mbedtls_ssl_ep_len( ssl ) )
3669 {
3670 MBEDTLS_SSL_DEBUG_MSG( 1, ( "incoming message counter would wrap" ) );
3671 return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
3672 }
3673 }
3674
3675 }
3676
3677 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
3678 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
3679 {
3680 mbedtls_ssl_dtls_replay_update( ssl );
3681 }
3682 #endif
3683
3684 /* Check actual (decrypted) record content length against
3685 * configured maximum. */
3686 if( ssl->in_msglen > MBEDTLS_SSL_IN_CONTENT_LEN )
3687 {
3688 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
3689 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
3690 }
3691
3692 return( 0 );
3693 }
3694
3695 /*
3696 * Read a record.
3697 *
3698 * Silently ignore non-fatal alert (and for DTLS, invalid records as well,
3699 * RFC 6347 4.1.2.7) and continue reading until a valid record is found.
3700 *
3701 */
3702
3703 /* Helper functions for mbedtls_ssl_read_record(). */
3704 static int ssl_consume_current_message( mbedtls_ssl_context *ssl );
3705 static int ssl_get_next_record( mbedtls_ssl_context *ssl );
3706 static int ssl_record_is_in_progress( mbedtls_ssl_context *ssl );
3707
mbedtls_ssl_read_record(mbedtls_ssl_context * ssl,unsigned update_hs_digest)3708 int mbedtls_ssl_read_record( mbedtls_ssl_context *ssl,
3709 unsigned update_hs_digest )
3710 {
3711 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
3712
3713 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> read record" ) );
3714
3715 if( ssl->keep_current_message == 0 )
3716 {
3717 do {
3718
3719 ret = ssl_consume_current_message( ssl );
3720 if( ret != 0 )
3721 return( ret );
3722
3723 if( ssl_record_is_in_progress( ssl ) == 0 )
3724 {
3725 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3726 int have_buffered = 0;
3727
3728 /* We only check for buffered messages if the
3729 * current datagram is fully consumed. */
3730 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
3731 ssl_next_record_is_in_datagram( ssl ) == 0 )
3732 {
3733 if( ssl_load_buffered_message( ssl ) == 0 )
3734 have_buffered = 1;
3735 }
3736
3737 if( have_buffered == 0 )
3738 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3739 {
3740 ret = ssl_get_next_record( ssl );
3741 if( ret == MBEDTLS_ERR_SSL_CONTINUE_PROCESSING )
3742 continue;
3743
3744 if( ret != 0 )
3745 {
3746 MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_get_next_record" ), ret );
3747 return( ret );
3748 }
3749 }
3750 }
3751
3752 ret = mbedtls_ssl_handle_message_type( ssl );
3753
3754 #if defined(MBEDTLS_SSL_PROTO_DTLS)
3755 if( ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE )
3756 {
3757 /* Buffer future message */
3758 ret = ssl_buffer_message( ssl );
3759 if( ret != 0 )
3760 return( ret );
3761
3762 ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
3763 }
3764 #endif /* MBEDTLS_SSL_PROTO_DTLS */
3765
3766 } while( MBEDTLS_ERR_SSL_NON_FATAL == ret ||
3767 MBEDTLS_ERR_SSL_CONTINUE_PROCESSING == ret );
3768
3769 if( 0 != ret )
3770 {
3771 MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ssl_handle_message_type" ), ret );
3772 return( ret );
3773 }
3774
3775 if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
3776 update_hs_digest == 1 )
3777 {
3778 mbedtls_ssl_update_handshake_status( ssl );
3779 }
3780 }
3781 else
3782 {
3783 MBEDTLS_SSL_DEBUG_MSG( 2, ( "reuse previously read message" ) );
3784 ssl->keep_current_message = 0;
3785 }
3786
3787 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= read record" ) );
3788
3789 return( 0 );
3790 }
3791
3792 #if defined(MBEDTLS_SSL_PROTO_DTLS)
ssl_next_record_is_in_datagram(mbedtls_ssl_context * ssl)3793 static int ssl_next_record_is_in_datagram( mbedtls_ssl_context *ssl )
3794 {
3795 if( ssl->in_left > ssl->next_record_offset )
3796 return( 1 );
3797
3798 return( 0 );
3799 }
3800
ssl_load_buffered_message(mbedtls_ssl_context * ssl)3801 static int ssl_load_buffered_message( mbedtls_ssl_context *ssl )
3802 {
3803 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
3804 mbedtls_ssl_hs_buffer * hs_buf;
3805 int ret = 0;
3806
3807 if( hs == NULL )
3808 return( -1 );
3809
3810 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_load_buffered_messsage" ) );
3811
3812 if( ssl->state == MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC ||
3813 ssl->state == MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
3814 {
3815 /* Check if we have seen a ChangeCipherSpec before.
3816 * If yes, synthesize a CCS record. */
3817 if( !hs->buffering.seen_ccs )
3818 {
3819 MBEDTLS_SSL_DEBUG_MSG( 2, ( "CCS not seen in the current flight" ) );
3820 ret = -1;
3821 goto exit;
3822 }
3823
3824 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Injecting buffered CCS message" ) );
3825 ssl->in_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC;
3826 ssl->in_msglen = 1;
3827 ssl->in_msg[0] = 1;
3828
3829 /* As long as they are equal, the exact value doesn't matter. */
3830 ssl->in_left = 0;
3831 ssl->next_record_offset = 0;
3832
3833 hs->buffering.seen_ccs = 0;
3834 goto exit;
3835 }
3836
3837 #if defined(MBEDTLS_DEBUG_C)
3838 /* Debug only */
3839 {
3840 unsigned offset;
3841 for( offset = 1; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++ )
3842 {
3843 hs_buf = &hs->buffering.hs[offset];
3844 if( hs_buf->is_valid == 1 )
3845 {
3846 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Future message with sequence number %u %s buffered.",
3847 hs->in_msg_seq + offset,
3848 hs_buf->is_complete ? "fully" : "partially" ) );
3849 }
3850 }
3851 }
3852 #endif /* MBEDTLS_DEBUG_C */
3853
3854 /* Check if we have buffered and/or fully reassembled the
3855 * next handshake message. */
3856 hs_buf = &hs->buffering.hs[0];
3857 if( ( hs_buf->is_valid == 1 ) && ( hs_buf->is_complete == 1 ) )
3858 {
3859 /* Synthesize a record containing the buffered HS message. */
3860 size_t msg_len = ( hs_buf->data[1] << 16 ) |
3861 ( hs_buf->data[2] << 8 ) |
3862 hs_buf->data[3];
3863
3864 /* Double-check that we haven't accidentally buffered
3865 * a message that doesn't fit into the input buffer. */
3866 if( msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN )
3867 {
3868 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
3869 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
3870 }
3871
3872 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Next handshake message has been buffered - load" ) );
3873 MBEDTLS_SSL_DEBUG_BUF( 3, "Buffered handshake message (incl. header)",
3874 hs_buf->data, msg_len + 12 );
3875
3876 ssl->in_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
3877 ssl->in_hslen = msg_len + 12;
3878 ssl->in_msglen = msg_len + 12;
3879 memcpy( ssl->in_msg, hs_buf->data, ssl->in_hslen );
3880
3881 ret = 0;
3882 goto exit;
3883 }
3884 else
3885 {
3886 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Next handshake message %u not or only partially bufffered",
3887 hs->in_msg_seq ) );
3888 }
3889
3890 ret = -1;
3891
3892 exit:
3893
3894 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_load_buffered_message" ) );
3895 return( ret );
3896 }
3897
ssl_buffer_make_space(mbedtls_ssl_context * ssl,size_t desired)3898 static int ssl_buffer_make_space( mbedtls_ssl_context *ssl,
3899 size_t desired )
3900 {
3901 int offset;
3902 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
3903 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Attempt to free buffered messages to have %u bytes available",
3904 (unsigned) desired ) );
3905
3906 /* Get rid of future records epoch first, if such exist. */
3907 ssl_free_buffered_record( ssl );
3908
3909 /* Check if we have enough space available now. */
3910 if( desired <= ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
3911 hs->buffering.total_bytes_buffered ) )
3912 {
3913 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Enough space available after freeing future epoch record" ) );
3914 return( 0 );
3915 }
3916
3917 /* We don't have enough space to buffer the next expected handshake
3918 * message. Remove buffers used for future messages to gain space,
3919 * starting with the most distant one. */
3920 for( offset = MBEDTLS_SSL_MAX_BUFFERED_HS - 1;
3921 offset >= 0; offset-- )
3922 {
3923 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Free buffering slot %d to make space for reassembly of next handshake message",
3924 offset ) );
3925
3926 ssl_buffering_free_slot( ssl, (uint8_t) offset );
3927
3928 /* Check if we have enough space available now. */
3929 if( desired <= ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
3930 hs->buffering.total_bytes_buffered ) )
3931 {
3932 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Enough space available after freeing buffered HS messages" ) );
3933 return( 0 );
3934 }
3935 }
3936
3937 return( -1 );
3938 }
3939
ssl_buffer_message(mbedtls_ssl_context * ssl)3940 static int ssl_buffer_message( mbedtls_ssl_context *ssl )
3941 {
3942 int ret = 0;
3943 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
3944
3945 if( hs == NULL )
3946 return( 0 );
3947
3948 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_buffer_message" ) );
3949
3950 switch( ssl->in_msgtype )
3951 {
3952 case MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC:
3953 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Remember CCS message" ) );
3954
3955 hs->buffering.seen_ccs = 1;
3956 break;
3957
3958 case MBEDTLS_SSL_MSG_HANDSHAKE:
3959 {
3960 unsigned recv_msg_seq_offset;
3961 unsigned recv_msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
3962 mbedtls_ssl_hs_buffer *hs_buf;
3963 size_t msg_len = ssl->in_hslen - 12;
3964
3965 /* We should never receive an old handshake
3966 * message - double-check nonetheless. */
3967 if( recv_msg_seq < ssl->handshake->in_msg_seq )
3968 {
3969 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
3970 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
3971 }
3972
3973 recv_msg_seq_offset = recv_msg_seq - ssl->handshake->in_msg_seq;
3974 if( recv_msg_seq_offset >= MBEDTLS_SSL_MAX_BUFFERED_HS )
3975 {
3976 /* Silently ignore -- message too far in the future */
3977 MBEDTLS_SSL_DEBUG_MSG( 2,
3978 ( "Ignore future HS message with sequence number %u, "
3979 "buffering window %u - %u",
3980 recv_msg_seq, ssl->handshake->in_msg_seq,
3981 ssl->handshake->in_msg_seq + MBEDTLS_SSL_MAX_BUFFERED_HS - 1 ) );
3982
3983 goto exit;
3984 }
3985
3986 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering HS message with sequence number %u, offset %u ",
3987 recv_msg_seq, recv_msg_seq_offset ) );
3988
3989 hs_buf = &hs->buffering.hs[ recv_msg_seq_offset ];
3990
3991 /* Check if the buffering for this seq nr has already commenced. */
3992 if( !hs_buf->is_valid )
3993 {
3994 size_t reassembly_buf_sz;
3995
3996 hs_buf->is_fragmented =
3997 ( ssl_hs_is_proper_fragment( ssl ) == 1 );
3998
3999 /* We copy the message back into the input buffer
4000 * after reassembly, so check that it's not too large.
4001 * This is an implementation-specific limitation
4002 * and not one from the standard, hence it is not
4003 * checked in ssl_check_hs_header(). */
4004 if( msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN )
4005 {
4006 /* Ignore message */
4007 goto exit;
4008 }
4009
4010 /* Check if we have enough space to buffer the message. */
4011 if( hs->buffering.total_bytes_buffered >
4012 MBEDTLS_SSL_DTLS_MAX_BUFFERING )
4013 {
4014 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
4015 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
4016 }
4017
4018 reassembly_buf_sz = ssl_get_reassembly_buffer_size( msg_len,
4019 hs_buf->is_fragmented );
4020
4021 if( reassembly_buf_sz > ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
4022 hs->buffering.total_bytes_buffered ) )
4023 {
4024 if( recv_msg_seq_offset > 0 )
4025 {
4026 /* If we can't buffer a future message because
4027 * of space limitations -- ignore. */
4028 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering of future message of size %" MBEDTLS_PRINTF_SIZET
4029 " would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET
4030 " (already %" MBEDTLS_PRINTF_SIZET
4031 " bytes buffered) -- ignore\n",
4032 msg_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
4033 hs->buffering.total_bytes_buffered ) );
4034 goto exit;
4035 }
4036 else
4037 {
4038 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering of future message of size %" MBEDTLS_PRINTF_SIZET
4039 " would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET
4040 " (already %" MBEDTLS_PRINTF_SIZET
4041 " bytes buffered) -- attempt to make space by freeing buffered future messages\n",
4042 msg_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
4043 hs->buffering.total_bytes_buffered ) );
4044 }
4045
4046 if( ssl_buffer_make_space( ssl, reassembly_buf_sz ) != 0 )
4047 {
4048 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reassembly of next message of size %" MBEDTLS_PRINTF_SIZET
4049 " (%" MBEDTLS_PRINTF_SIZET " with bitmap) would exceed"
4050 " the compile-time limit %" MBEDTLS_PRINTF_SIZET
4051 " (already %" MBEDTLS_PRINTF_SIZET
4052 " bytes buffered) -- fail\n",
4053 msg_len,
4054 reassembly_buf_sz,
4055 (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
4056 hs->buffering.total_bytes_buffered ) );
4057 ret = MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
4058 goto exit;
4059 }
4060 }
4061
4062 MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialize reassembly, total length = %" MBEDTLS_PRINTF_SIZET,
4063 msg_len ) );
4064
4065 hs_buf->data = mbedtls_calloc( 1, reassembly_buf_sz );
4066 if( hs_buf->data == NULL )
4067 {
4068 ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
4069 goto exit;
4070 }
4071 hs_buf->data_len = reassembly_buf_sz;
4072
4073 /* Prepare final header: copy msg_type, length and message_seq,
4074 * then add standardised fragment_offset and fragment_length */
4075 memcpy( hs_buf->data, ssl->in_msg, 6 );
4076 memset( hs_buf->data + 6, 0, 3 );
4077 memcpy( hs_buf->data + 9, hs_buf->data + 1, 3 );
4078
4079 hs_buf->is_valid = 1;
4080
4081 hs->buffering.total_bytes_buffered += reassembly_buf_sz;
4082 }
4083 else
4084 {
4085 /* Make sure msg_type and length are consistent */
4086 if( memcmp( hs_buf->data, ssl->in_msg, 4 ) != 0 )
4087 {
4088 MBEDTLS_SSL_DEBUG_MSG( 1, ( "Fragment header mismatch - ignore" ) );
4089 /* Ignore */
4090 goto exit;
4091 }
4092 }
4093
4094 if( !hs_buf->is_complete )
4095 {
4096 size_t frag_len, frag_off;
4097 unsigned char * const msg = hs_buf->data + 12;
4098
4099 /*
4100 * Check and copy current fragment
4101 */
4102
4103 /* Validation of header fields already done in
4104 * mbedtls_ssl_prepare_handshake_record(). */
4105 frag_off = ssl_get_hs_frag_off( ssl );
4106 frag_len = ssl_get_hs_frag_len( ssl );
4107
4108 MBEDTLS_SSL_DEBUG_MSG( 2, ( "adding fragment, offset = %" MBEDTLS_PRINTF_SIZET
4109 ", length = %" MBEDTLS_PRINTF_SIZET,
4110 frag_off, frag_len ) );
4111 memcpy( msg + frag_off, ssl->in_msg + 12, frag_len );
4112
4113 if( hs_buf->is_fragmented )
4114 {
4115 unsigned char * const bitmask = msg + msg_len;
4116 ssl_bitmask_set( bitmask, frag_off, frag_len );
4117 hs_buf->is_complete = ( ssl_bitmask_check( bitmask,
4118 msg_len ) == 0 );
4119 }
4120 else
4121 {
4122 hs_buf->is_complete = 1;
4123 }
4124
4125 MBEDTLS_SSL_DEBUG_MSG( 2, ( "message %scomplete",
4126 hs_buf->is_complete ? "" : "not yet " ) );
4127 }
4128
4129 break;
4130 }
4131
4132 default:
4133 /* We don't buffer other types of messages. */
4134 break;
4135 }
4136
4137 exit:
4138
4139 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_buffer_message" ) );
4140 return( ret );
4141 }
4142 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4143
ssl_consume_current_message(mbedtls_ssl_context * ssl)4144 static int ssl_consume_current_message( mbedtls_ssl_context *ssl )
4145 {
4146 /*
4147 * Consume last content-layer message and potentially
4148 * update in_msglen which keeps track of the contents'
4149 * consumption state.
4150 *
4151 * (1) Handshake messages:
4152 * Remove last handshake message, move content
4153 * and adapt in_msglen.
4154 *
4155 * (2) Alert messages:
4156 * Consume whole record content, in_msglen = 0.
4157 *
4158 * (3) Change cipher spec:
4159 * Consume whole record content, in_msglen = 0.
4160 *
4161 * (4) Application data:
4162 * Don't do anything - the record layer provides
4163 * the application data as a stream transport
4164 * and consumes through mbedtls_ssl_read only.
4165 *
4166 */
4167
4168 /* Case (1): Handshake messages */
4169 if( ssl->in_hslen != 0 )
4170 {
4171 /* Hard assertion to be sure that no application data
4172 * is in flight, as corrupting ssl->in_msglen during
4173 * ssl->in_offt != NULL is fatal. */
4174 if( ssl->in_offt != NULL )
4175 {
4176 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
4177 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
4178 }
4179
4180 /*
4181 * Get next Handshake message in the current record
4182 */
4183
4184 /* Notes:
4185 * (1) in_hslen is not necessarily the size of the
4186 * current handshake content: If DTLS handshake
4187 * fragmentation is used, that's the fragment
4188 * size instead. Using the total handshake message
4189 * size here is faulty and should be changed at
4190 * some point.
4191 * (2) While it doesn't seem to cause problems, one
4192 * has to be very careful not to assume that in_hslen
4193 * is always <= in_msglen in a sensible communication.
4194 * Again, it's wrong for DTLS handshake fragmentation.
4195 * The following check is therefore mandatory, and
4196 * should not be treated as a silently corrected assertion.
4197 * Additionally, ssl->in_hslen might be arbitrarily out of
4198 * bounds after handling a DTLS message with an unexpected
4199 * sequence number, see mbedtls_ssl_prepare_handshake_record.
4200 */
4201 if( ssl->in_hslen < ssl->in_msglen )
4202 {
4203 ssl->in_msglen -= ssl->in_hslen;
4204 memmove( ssl->in_msg, ssl->in_msg + ssl->in_hslen,
4205 ssl->in_msglen );
4206
4207 MBEDTLS_SSL_DEBUG_BUF( 4, "remaining content in record",
4208 ssl->in_msg, ssl->in_msglen );
4209 }
4210 else
4211 {
4212 ssl->in_msglen = 0;
4213 }
4214
4215 ssl->in_hslen = 0;
4216 }
4217 /* Case (4): Application data */
4218 else if( ssl->in_offt != NULL )
4219 {
4220 return( 0 );
4221 }
4222 /* Everything else (CCS & Alerts) */
4223 else
4224 {
4225 ssl->in_msglen = 0;
4226 }
4227
4228 return( 0 );
4229 }
4230
ssl_record_is_in_progress(mbedtls_ssl_context * ssl)4231 static int ssl_record_is_in_progress( mbedtls_ssl_context *ssl )
4232 {
4233 if( ssl->in_msglen > 0 )
4234 return( 1 );
4235
4236 return( 0 );
4237 }
4238
4239 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4240
ssl_free_buffered_record(mbedtls_ssl_context * ssl)4241 static void ssl_free_buffered_record( mbedtls_ssl_context *ssl )
4242 {
4243 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
4244 if( hs == NULL )
4245 return;
4246
4247 if( hs->buffering.future_record.data != NULL )
4248 {
4249 hs->buffering.total_bytes_buffered -=
4250 hs->buffering.future_record.len;
4251
4252 mbedtls_free( hs->buffering.future_record.data );
4253 hs->buffering.future_record.data = NULL;
4254 }
4255 }
4256
ssl_load_buffered_record(mbedtls_ssl_context * ssl)4257 static int ssl_load_buffered_record( mbedtls_ssl_context *ssl )
4258 {
4259 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
4260 unsigned char * rec;
4261 size_t rec_len;
4262 unsigned rec_epoch;
4263 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
4264 size_t in_buf_len = ssl->in_buf_len;
4265 #else
4266 size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN;
4267 #endif
4268 if( ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM )
4269 return( 0 );
4270
4271 if( hs == NULL )
4272 return( 0 );
4273
4274 rec = hs->buffering.future_record.data;
4275 rec_len = hs->buffering.future_record.len;
4276 rec_epoch = hs->buffering.future_record.epoch;
4277
4278 if( rec == NULL )
4279 return( 0 );
4280
4281 /* Only consider loading future records if the
4282 * input buffer is empty. */
4283 if( ssl_next_record_is_in_datagram( ssl ) == 1 )
4284 return( 0 );
4285
4286 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_load_buffered_record" ) );
4287
4288 if( rec_epoch != ssl->in_epoch )
4289 {
4290 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffered record not from current epoch." ) );
4291 goto exit;
4292 }
4293
4294 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Found buffered record from current epoch - load" ) );
4295
4296 /* Double-check that the record is not too large */
4297 if( rec_len > in_buf_len - (size_t)( ssl->in_hdr - ssl->in_buf ) )
4298 {
4299 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
4300 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
4301 }
4302
4303 memcpy( ssl->in_hdr, rec, rec_len );
4304 ssl->in_left = rec_len;
4305 ssl->next_record_offset = 0;
4306
4307 ssl_free_buffered_record( ssl );
4308
4309 exit:
4310 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_load_buffered_record" ) );
4311 return( 0 );
4312 }
4313
ssl_buffer_future_record(mbedtls_ssl_context * ssl,mbedtls_record const * rec)4314 static int ssl_buffer_future_record( mbedtls_ssl_context *ssl,
4315 mbedtls_record const *rec )
4316 {
4317 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
4318
4319 /* Don't buffer future records outside handshakes. */
4320 if( hs == NULL )
4321 return( 0 );
4322
4323 /* Only buffer handshake records (we are only interested
4324 * in Finished messages). */
4325 if( rec->type != MBEDTLS_SSL_MSG_HANDSHAKE )
4326 return( 0 );
4327
4328 /* Don't buffer more than one future epoch record. */
4329 if( hs->buffering.future_record.data != NULL )
4330 return( 0 );
4331
4332 /* Don't buffer record if there's not enough buffering space remaining. */
4333 if( rec->buf_len > ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
4334 hs->buffering.total_bytes_buffered ) )
4335 {
4336 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering of future epoch record of size %" MBEDTLS_PRINTF_SIZET
4337 " would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET
4338 " (already %" MBEDTLS_PRINTF_SIZET
4339 " bytes buffered) -- ignore\n",
4340 rec->buf_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
4341 hs->buffering.total_bytes_buffered ) );
4342 return( 0 );
4343 }
4344
4345 /* Buffer record */
4346 MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffer record from epoch %u",
4347 ssl->in_epoch + 1U ) );
4348 MBEDTLS_SSL_DEBUG_BUF( 3, "Buffered record", rec->buf, rec->buf_len );
4349
4350 /* ssl_parse_record_header() only considers records
4351 * of the next epoch as candidates for buffering. */
4352 hs->buffering.future_record.epoch = ssl->in_epoch + 1;
4353 hs->buffering.future_record.len = rec->buf_len;
4354
4355 hs->buffering.future_record.data =
4356 mbedtls_calloc( 1, hs->buffering.future_record.len );
4357 if( hs->buffering.future_record.data == NULL )
4358 {
4359 /* If we run out of RAM trying to buffer a
4360 * record from the next epoch, just ignore. */
4361 return( 0 );
4362 }
4363
4364 memcpy( hs->buffering.future_record.data, rec->buf, rec->buf_len );
4365
4366 hs->buffering.total_bytes_buffered += rec->buf_len;
4367 return( 0 );
4368 }
4369
4370 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4371
ssl_get_next_record(mbedtls_ssl_context * ssl)4372 static int ssl_get_next_record( mbedtls_ssl_context *ssl )
4373 {
4374 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
4375 mbedtls_record rec;
4376
4377 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4378 /* We might have buffered a future record; if so,
4379 * and if the epoch matches now, load it.
4380 * On success, this call will set ssl->in_left to
4381 * the length of the buffered record, so that
4382 * the calls to ssl_fetch_input() below will
4383 * essentially be no-ops. */
4384 ret = ssl_load_buffered_record( ssl );
4385 if( ret != 0 )
4386 return( ret );
4387 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4388
4389 /* Ensure that we have enough space available for the default form
4390 * of TLS / DTLS record headers (5 Bytes for TLS, 13 Bytes for DTLS,
4391 * with no space for CIDs counted in). */
4392 ret = mbedtls_ssl_fetch_input( ssl, mbedtls_ssl_in_hdr_len( ssl ) );
4393 if( ret != 0 )
4394 {
4395 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_fetch_input", ret );
4396 return( ret );
4397 }
4398
4399 ret = ssl_parse_record_header( ssl, ssl->in_hdr, ssl->in_left, &rec );
4400 if( ret != 0 )
4401 {
4402 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4403 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
4404 {
4405 if( ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE )
4406 {
4407 ret = ssl_buffer_future_record( ssl, &rec );
4408 if( ret != 0 )
4409 return( ret );
4410
4411 /* Fall through to handling of unexpected records */
4412 ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD;
4413 }
4414
4415 if( ret == MBEDTLS_ERR_SSL_UNEXPECTED_RECORD )
4416 {
4417 #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
4418 /* Reset in pointers to default state for TLS/DTLS records,
4419 * assuming no CID and no offset between record content and
4420 * record plaintext. */
4421 mbedtls_ssl_update_in_pointers( ssl );
4422
4423 /* Setup internal message pointers from record structure. */
4424 ssl->in_msgtype = rec.type;
4425 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
4426 ssl->in_len = ssl->in_cid + rec.cid_len;
4427 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
4428 ssl->in_iv = ssl->in_msg = ssl->in_len + 2;
4429 ssl->in_msglen = rec.data_len;
4430
4431 ret = ssl_check_client_reconnect( ssl );
4432 MBEDTLS_SSL_DEBUG_RET( 2, "ssl_check_client_reconnect", ret );
4433 if( ret != 0 )
4434 return( ret );
4435 #endif
4436
4437 /* Skip unexpected record (but not whole datagram) */
4438 ssl->next_record_offset = rec.buf_len;
4439
4440 MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding unexpected record "
4441 "(header)" ) );
4442 }
4443 else
4444 {
4445 /* Skip invalid record and the rest of the datagram */
4446 ssl->next_record_offset = 0;
4447 ssl->in_left = 0;
4448
4449 MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding invalid record "
4450 "(header)" ) );
4451 }
4452
4453 /* Get next record */
4454 return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
4455 }
4456 else
4457 #endif
4458 {
4459 return( ret );
4460 }
4461 }
4462
4463 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4464 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
4465 {
4466 /* Remember offset of next record within datagram. */
4467 ssl->next_record_offset = rec.buf_len;
4468 if( ssl->next_record_offset < ssl->in_left )
4469 {
4470 MBEDTLS_SSL_DEBUG_MSG( 3, ( "more than one record within datagram" ) );
4471 }
4472 }
4473 else
4474 #endif
4475 {
4476 /*
4477 * Fetch record contents from underlying transport.
4478 */
4479 ret = mbedtls_ssl_fetch_input( ssl, rec.buf_len );
4480 if( ret != 0 )
4481 {
4482 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_fetch_input", ret );
4483 return( ret );
4484 }
4485
4486 ssl->in_left = 0;
4487 }
4488
4489 /*
4490 * Decrypt record contents.
4491 */
4492
4493 if( ( ret = ssl_prepare_record_content( ssl, &rec ) ) != 0 )
4494 {
4495 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4496 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
4497 {
4498 /* Silently discard invalid records */
4499 if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
4500 {
4501 /* Except when waiting for Finished as a bad mac here
4502 * probably means something went wrong in the handshake
4503 * (eg wrong psk used, mitm downgrade attempt, etc.) */
4504 if( ssl->state == MBEDTLS_SSL_CLIENT_FINISHED ||
4505 ssl->state == MBEDTLS_SSL_SERVER_FINISHED )
4506 {
4507 #if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES)
4508 if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
4509 {
4510 mbedtls_ssl_send_alert_message( ssl,
4511 MBEDTLS_SSL_ALERT_LEVEL_FATAL,
4512 MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC );
4513 }
4514 #endif
4515 return( ret );
4516 }
4517
4518 if( ssl->conf->badmac_limit != 0 &&
4519 ++ssl->badmac_seen >= ssl->conf->badmac_limit )
4520 {
4521 MBEDTLS_SSL_DEBUG_MSG( 1, ( "too many records with bad MAC" ) );
4522 return( MBEDTLS_ERR_SSL_INVALID_MAC );
4523 }
4524
4525 /* As above, invalid records cause
4526 * dismissal of the whole datagram. */
4527
4528 ssl->next_record_offset = 0;
4529 ssl->in_left = 0;
4530
4531 MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding invalid record (mac)" ) );
4532 return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
4533 }
4534
4535 return( ret );
4536 }
4537 else
4538 #endif
4539 {
4540 /* Error out (and send alert) on invalid records */
4541 #if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES)
4542 if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
4543 {
4544 mbedtls_ssl_send_alert_message( ssl,
4545 MBEDTLS_SSL_ALERT_LEVEL_FATAL,
4546 MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC );
4547 }
4548 #endif
4549 return( ret );
4550 }
4551 }
4552
4553
4554 /* Reset in pointers to default state for TLS/DTLS records,
4555 * assuming no CID and no offset between record content and
4556 * record plaintext. */
4557 mbedtls_ssl_update_in_pointers( ssl );
4558 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
4559 ssl->in_len = ssl->in_cid + rec.cid_len;
4560 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
4561 ssl->in_iv = ssl->in_len + 2;
4562
4563 /* The record content type may change during decryption,
4564 * so re-read it. */
4565 ssl->in_msgtype = rec.type;
4566 /* Also update the input buffer, because unfortunately
4567 * the server-side ssl_parse_client_hello() reparses the
4568 * record header when receiving a ClientHello initiating
4569 * a renegotiation. */
4570 ssl->in_hdr[0] = rec.type;
4571 ssl->in_msg = rec.buf + rec.data_offset;
4572 ssl->in_msglen = rec.data_len;
4573 MBEDTLS_PUT_UINT16_BE( rec.data_len, ssl->in_len, 0 );
4574
4575 return( 0 );
4576 }
4577
mbedtls_ssl_handle_message_type(mbedtls_ssl_context * ssl)4578 int mbedtls_ssl_handle_message_type( mbedtls_ssl_context *ssl )
4579 {
4580 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
4581
4582 /*
4583 * Handle particular types of records
4584 */
4585 if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
4586 {
4587 if( ( ret = mbedtls_ssl_prepare_handshake_record( ssl ) ) != 0 )
4588 {
4589 return( ret );
4590 }
4591 }
4592
4593 if( ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
4594 {
4595 if( ssl->in_msglen != 1 )
4596 {
4597 MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid CCS message, len: %" MBEDTLS_PRINTF_SIZET,
4598 ssl->in_msglen ) );
4599 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
4600 }
4601
4602 if( ssl->in_msg[0] != 1 )
4603 {
4604 MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid CCS message, content: %02x",
4605 ssl->in_msg[0] ) );
4606 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
4607 }
4608
4609 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4610 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
4611 ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC &&
4612 ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
4613 {
4614 if( ssl->handshake == NULL )
4615 {
4616 MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping ChangeCipherSpec outside handshake" ) );
4617 return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
4618 }
4619
4620 MBEDTLS_SSL_DEBUG_MSG( 1, ( "received out-of-order ChangeCipherSpec - remember" ) );
4621 return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
4622 }
4623 #endif
4624 }
4625
4626 if( ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT )
4627 {
4628 if( ssl->in_msglen != 2 )
4629 {
4630 /* Note: Standard allows for more than one 2 byte alert
4631 to be packed in a single message, but Mbed TLS doesn't
4632 currently support this. */
4633 MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid alert message, len: %" MBEDTLS_PRINTF_SIZET,
4634 ssl->in_msglen ) );
4635 return( MBEDTLS_ERR_SSL_INVALID_RECORD );
4636 }
4637
4638 MBEDTLS_SSL_DEBUG_MSG( 2, ( "got an alert message, type: [%u:%u]",
4639 ssl->in_msg[0], ssl->in_msg[1] ) );
4640
4641 /*
4642 * Ignore non-fatal alerts, except close_notify and no_renegotiation
4643 */
4644 if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_FATAL )
4645 {
4646 MBEDTLS_SSL_DEBUG_MSG( 1, ( "is a fatal alert message (msg %d)",
4647 ssl->in_msg[1] ) );
4648 return( MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE );
4649 }
4650
4651 if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
4652 ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY )
4653 {
4654 MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a close notify message" ) );
4655 return( MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY );
4656 }
4657
4658 #if defined(MBEDTLS_SSL_RENEGOTIATION_ENABLED)
4659 if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
4660 ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION )
4661 {
4662 MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a no renegotiation alert" ) );
4663 /* Will be handled when trying to parse ServerHello */
4664 return( 0 );
4665 }
4666 #endif
4667 /* Silently ignore: fetch new message */
4668 return MBEDTLS_ERR_SSL_NON_FATAL;
4669 }
4670
4671 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4672 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
4673 {
4674 /* Drop unexpected ApplicationData records,
4675 * except at the beginning of renegotiations */
4676 if( ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA &&
4677 ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER
4678 #if defined(MBEDTLS_SSL_RENEGOTIATION)
4679 && ! ( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
4680 ssl->state == MBEDTLS_SSL_SERVER_HELLO )
4681 #endif
4682 )
4683 {
4684 MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ApplicationData" ) );
4685 return( MBEDTLS_ERR_SSL_NON_FATAL );
4686 }
4687
4688 if( ssl->handshake != NULL &&
4689 ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
4690 {
4691 mbedtls_ssl_handshake_wrapup_free_hs_transform( ssl );
4692 }
4693 }
4694 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4695
4696 return( 0 );
4697 }
4698
mbedtls_ssl_send_fatal_handshake_failure(mbedtls_ssl_context * ssl)4699 int mbedtls_ssl_send_fatal_handshake_failure( mbedtls_ssl_context *ssl )
4700 {
4701 return( mbedtls_ssl_send_alert_message( ssl,
4702 MBEDTLS_SSL_ALERT_LEVEL_FATAL,
4703 MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE ) );
4704 }
4705
mbedtls_ssl_send_alert_message(mbedtls_ssl_context * ssl,unsigned char level,unsigned char message)4706 int mbedtls_ssl_send_alert_message( mbedtls_ssl_context *ssl,
4707 unsigned char level,
4708 unsigned char message )
4709 {
4710 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
4711
4712 if( ssl == NULL || ssl->conf == NULL )
4713 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
4714
4715 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> send alert message" ) );
4716 MBEDTLS_SSL_DEBUG_MSG( 3, ( "send alert level=%u message=%u", level, message ));
4717
4718 ssl->out_msgtype = MBEDTLS_SSL_MSG_ALERT;
4719 ssl->out_msglen = 2;
4720 ssl->out_msg[0] = level;
4721 ssl->out_msg[1] = message;
4722
4723 if( ( ret = mbedtls_ssl_write_record( ssl, SSL_FORCE_FLUSH ) ) != 0 )
4724 {
4725 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
4726 return( ret );
4727 }
4728 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= send alert message" ) );
4729
4730 return( 0 );
4731 }
4732
mbedtls_ssl_write_change_cipher_spec(mbedtls_ssl_context * ssl)4733 int mbedtls_ssl_write_change_cipher_spec( mbedtls_ssl_context *ssl )
4734 {
4735 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
4736
4737 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write change cipher spec" ) );
4738
4739 ssl->out_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC;
4740 ssl->out_msglen = 1;
4741 ssl->out_msg[0] = 1;
4742
4743 ssl->state++;
4744
4745 if( ( ret = mbedtls_ssl_write_handshake_msg( ssl ) ) != 0 )
4746 {
4747 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_handshake_msg", ret );
4748 return( ret );
4749 }
4750
4751 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write change cipher spec" ) );
4752
4753 return( 0 );
4754 }
4755
mbedtls_ssl_parse_change_cipher_spec(mbedtls_ssl_context * ssl)4756 int mbedtls_ssl_parse_change_cipher_spec( mbedtls_ssl_context *ssl )
4757 {
4758 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
4759
4760 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse change cipher spec" ) );
4761
4762 if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
4763 {
4764 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
4765 return( ret );
4766 }
4767
4768 if( ssl->in_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
4769 {
4770 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad change cipher spec message" ) );
4771 mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
4772 MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
4773 return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
4774 }
4775
4776 /* CCS records are only accepted if they have length 1 and content '1',
4777 * so we don't need to check this here. */
4778
4779 /*
4780 * Switch to our negotiated transform and session parameters for inbound
4781 * data.
4782 */
4783 MBEDTLS_SSL_DEBUG_MSG( 3, ( "switching to new transform spec for inbound data" ) );
4784 ssl->transform_in = ssl->transform_negotiate;
4785 ssl->session_in = ssl->session_negotiate;
4786
4787 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4788 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
4789 {
4790 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
4791 mbedtls_ssl_dtls_replay_reset( ssl );
4792 #endif
4793
4794 /* Increment epoch */
4795 if( ++ssl->in_epoch == 0 )
4796 {
4797 MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS epoch would wrap" ) );
4798 /* This is highly unlikely to happen for legitimate reasons, so
4799 treat it as an attack and don't send an alert. */
4800 return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
4801 }
4802 }
4803 else
4804 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4805 memset( ssl->in_ctr, 0, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN );
4806
4807 mbedtls_ssl_update_in_pointers( ssl );
4808
4809 ssl->state++;
4810
4811 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse change cipher spec" ) );
4812
4813 return( 0 );
4814 }
4815
4816 /* Once ssl->out_hdr as the address of the beginning of the
4817 * next outgoing record is set, deduce the other pointers.
4818 *
4819 * Note: For TLS, we save the implicit record sequence number
4820 * (entering MAC computation) in the 8 bytes before ssl->out_hdr,
4821 * and the caller has to make sure there's space for this.
4822 */
4823
ssl_transform_get_explicit_iv_len(mbedtls_ssl_transform const * transform)4824 static size_t ssl_transform_get_explicit_iv_len(
4825 mbedtls_ssl_transform const *transform )
4826 {
4827 if( transform->minor_ver < MBEDTLS_SSL_MINOR_VERSION_3 )
4828 return( 0 );
4829
4830 return( transform->ivlen - transform->fixed_ivlen );
4831 }
4832
mbedtls_ssl_update_out_pointers(mbedtls_ssl_context * ssl,mbedtls_ssl_transform * transform)4833 void mbedtls_ssl_update_out_pointers( mbedtls_ssl_context *ssl,
4834 mbedtls_ssl_transform *transform )
4835 {
4836 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4837 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
4838 {
4839 ssl->out_ctr = ssl->out_hdr + 3;
4840 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
4841 ssl->out_cid = ssl->out_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
4842 ssl->out_len = ssl->out_cid;
4843 if( transform != NULL )
4844 ssl->out_len += transform->out_cid_len;
4845 #else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
4846 ssl->out_len = ssl->out_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
4847 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
4848 ssl->out_iv = ssl->out_len + 2;
4849 }
4850 else
4851 #endif
4852 {
4853 ssl->out_len = ssl->out_hdr + 3;
4854 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
4855 ssl->out_cid = ssl->out_len;
4856 #endif
4857 ssl->out_iv = ssl->out_hdr + 5;
4858 }
4859
4860 ssl->out_msg = ssl->out_iv;
4861 /* Adjust out_msg to make space for explicit IV, if used. */
4862 if( transform != NULL )
4863 ssl->out_msg += ssl_transform_get_explicit_iv_len( transform );
4864 }
4865
4866 /* Once ssl->in_hdr as the address of the beginning of the
4867 * next incoming record is set, deduce the other pointers.
4868 *
4869 * Note: For TLS, we save the implicit record sequence number
4870 * (entering MAC computation) in the 8 bytes before ssl->in_hdr,
4871 * and the caller has to make sure there's space for this.
4872 */
4873
mbedtls_ssl_update_in_pointers(mbedtls_ssl_context * ssl)4874 void mbedtls_ssl_update_in_pointers( mbedtls_ssl_context *ssl )
4875 {
4876 /* This function sets the pointers to match the case
4877 * of unprotected TLS/DTLS records, with both ssl->in_iv
4878 * and ssl->in_msg pointing to the beginning of the record
4879 * content.
4880 *
4881 * When decrypting a protected record, ssl->in_msg
4882 * will be shifted to point to the beginning of the
4883 * record plaintext.
4884 */
4885
4886 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4887 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
4888 {
4889 /* This sets the header pointers to match records
4890 * without CID. When we receive a record containing
4891 * a CID, the fields are shifted accordingly in
4892 * ssl_parse_record_header(). */
4893 ssl->in_ctr = ssl->in_hdr + 3;
4894 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
4895 ssl->in_cid = ssl->in_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
4896 ssl->in_len = ssl->in_cid; /* Default: no CID */
4897 #else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
4898 ssl->in_len = ssl->in_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
4899 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
4900 ssl->in_iv = ssl->in_len + 2;
4901 }
4902 else
4903 #endif
4904 {
4905 ssl->in_ctr = ssl->in_hdr - MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
4906 ssl->in_len = ssl->in_hdr + 3;
4907 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
4908 ssl->in_cid = ssl->in_len;
4909 #endif
4910 ssl->in_iv = ssl->in_hdr + 5;
4911 }
4912
4913 /* This will be adjusted at record decryption time. */
4914 ssl->in_msg = ssl->in_iv;
4915 }
4916
4917 /*
4918 * Setup an SSL context
4919 */
4920
mbedtls_ssl_reset_in_out_pointers(mbedtls_ssl_context * ssl)4921 void mbedtls_ssl_reset_in_out_pointers( mbedtls_ssl_context *ssl )
4922 {
4923 /* Set the incoming and outgoing record pointers. */
4924 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4925 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
4926 {
4927 ssl->out_hdr = ssl->out_buf;
4928 ssl->in_hdr = ssl->in_buf;
4929 }
4930 else
4931 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4932 {
4933 ssl->out_ctr = ssl->out_buf;
4934 ssl->out_hdr = ssl->out_buf + 8;
4935 ssl->in_hdr = ssl->in_buf + 8;
4936 }
4937
4938 /* Derive other internal pointers. */
4939 mbedtls_ssl_update_out_pointers( ssl, NULL /* no transform enabled */ );
4940 mbedtls_ssl_update_in_pointers ( ssl );
4941 }
4942
4943 /*
4944 * SSL get accessors
4945 */
mbedtls_ssl_get_bytes_avail(const mbedtls_ssl_context * ssl)4946 size_t mbedtls_ssl_get_bytes_avail( const mbedtls_ssl_context *ssl )
4947 {
4948 return( ssl->in_offt == NULL ? 0 : ssl->in_msglen );
4949 }
4950
mbedtls_ssl_check_pending(const mbedtls_ssl_context * ssl)4951 int mbedtls_ssl_check_pending( const mbedtls_ssl_context *ssl )
4952 {
4953 /*
4954 * Case A: We're currently holding back
4955 * a message for further processing.
4956 */
4957
4958 if( ssl->keep_current_message == 1 )
4959 {
4960 MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: record held back for processing" ) );
4961 return( 1 );
4962 }
4963
4964 /*
4965 * Case B: Further records are pending in the current datagram.
4966 */
4967
4968 #if defined(MBEDTLS_SSL_PROTO_DTLS)
4969 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
4970 ssl->in_left > ssl->next_record_offset )
4971 {
4972 MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: more records within current datagram" ) );
4973 return( 1 );
4974 }
4975 #endif /* MBEDTLS_SSL_PROTO_DTLS */
4976
4977 /*
4978 * Case C: A handshake message is being processed.
4979 */
4980
4981 if( ssl->in_hslen > 0 && ssl->in_hslen < ssl->in_msglen )
4982 {
4983 MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: more handshake messages within current record" ) );
4984 return( 1 );
4985 }
4986
4987 /*
4988 * Case D: An application data message is being processed
4989 */
4990 if( ssl->in_offt != NULL )
4991 {
4992 MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: application data record is being processed" ) );
4993 return( 1 );
4994 }
4995
4996 /*
4997 * In all other cases, the rest of the message can be dropped.
4998 * As in ssl_get_next_record, this needs to be adapted if
4999 * we implement support for multiple alerts in single records.
5000 */
5001
5002 MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: nothing pending" ) );
5003 return( 0 );
5004 }
5005
5006
mbedtls_ssl_get_record_expansion(const mbedtls_ssl_context * ssl)5007 int mbedtls_ssl_get_record_expansion( const mbedtls_ssl_context *ssl )
5008 {
5009 size_t transform_expansion = 0;
5010 const mbedtls_ssl_transform *transform = ssl->transform_out;
5011 unsigned block_size;
5012
5013 size_t out_hdr_len = mbedtls_ssl_out_hdr_len( ssl );
5014
5015 if( transform == NULL )
5016 return( (int) out_hdr_len );
5017
5018 switch( mbedtls_cipher_get_cipher_mode( &transform->cipher_ctx_enc ) )
5019 {
5020 case MBEDTLS_MODE_GCM:
5021 case MBEDTLS_MODE_CCM:
5022 case MBEDTLS_MODE_CHACHAPOLY:
5023 case MBEDTLS_MODE_STREAM:
5024 transform_expansion = transform->minlen;
5025 break;
5026
5027 case MBEDTLS_MODE_CBC:
5028
5029 block_size = mbedtls_cipher_get_block_size(
5030 &transform->cipher_ctx_enc );
5031
5032 /* Expansion due to the addition of the MAC. */
5033 transform_expansion += transform->maclen;
5034
5035 /* Expansion due to the addition of CBC padding;
5036 * Theoretically up to 256 bytes, but we never use
5037 * more than the block size of the underlying cipher. */
5038 transform_expansion += block_size;
5039
5040 /* For TLS 1.2 or higher, an explicit IV is added
5041 * after the record header. */
5042 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
5043 transform_expansion += block_size;
5044 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
5045
5046 break;
5047
5048 default:
5049 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
5050 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
5051 }
5052
5053 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
5054 if( transform->out_cid_len != 0 )
5055 transform_expansion += MBEDTLS_SSL_MAX_CID_EXPANSION;
5056 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
5057
5058 return( (int)( out_hdr_len + transform_expansion ) );
5059 }
5060
5061 #if defined(MBEDTLS_SSL_RENEGOTIATION)
5062 /*
5063 * Check record counters and renegotiate if they're above the limit.
5064 */
ssl_check_ctr_renegotiate(mbedtls_ssl_context * ssl)5065 static int ssl_check_ctr_renegotiate( mbedtls_ssl_context *ssl )
5066 {
5067 size_t ep_len = mbedtls_ssl_ep_len( ssl );
5068 int in_ctr_cmp;
5069 int out_ctr_cmp;
5070
5071 if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER ||
5072 ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING ||
5073 ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED )
5074 {
5075 return( 0 );
5076 }
5077
5078 in_ctr_cmp = memcmp( ssl->in_ctr + ep_len,
5079 &ssl->conf->renego_period[ep_len],
5080 MBEDTLS_SSL_SEQUENCE_NUMBER_LEN - ep_len );
5081 out_ctr_cmp = memcmp( &ssl->cur_out_ctr[ep_len],
5082 &ssl->conf->renego_period[ep_len],
5083 sizeof( ssl->cur_out_ctr ) - ep_len );
5084
5085 if( in_ctr_cmp <= 0 && out_ctr_cmp <= 0 )
5086 {
5087 return( 0 );
5088 }
5089
5090 MBEDTLS_SSL_DEBUG_MSG( 1, ( "record counter limit reached: renegotiate" ) );
5091 return( mbedtls_ssl_renegotiate( ssl ) );
5092 }
5093 #endif /* MBEDTLS_SSL_RENEGOTIATION */
5094
5095 /* This function is called from mbedtls_ssl_read() when a handshake message is
5096 * received after the initial handshake. In this context, handshake messages
5097 * may only be sent for the purpose of initiating renegotiations.
5098 *
5099 * This function is introduced as a separate helper since the handling
5100 * of post-handshake handshake messages changes significantly in TLS 1.3,
5101 * and having a helper function allows to distinguish between TLS <= 1.2 and
5102 * TLS 1.3 in the future without bloating the logic of mbedtls_ssl_read().
5103 */
ssl_handle_hs_message_post_handshake(mbedtls_ssl_context * ssl)5104 static int ssl_handle_hs_message_post_handshake( mbedtls_ssl_context *ssl )
5105 {
5106 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
5107
5108 /*
5109 * - For client-side, expect SERVER_HELLO_REQUEST.
5110 * - For server-side, expect CLIENT_HELLO.
5111 * - Fail (TLS) or silently drop record (DTLS) in other cases.
5112 */
5113
5114 #if defined(MBEDTLS_SSL_CLI_C)
5115 if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
5116 ( ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_REQUEST ||
5117 ssl->in_hslen != mbedtls_ssl_hs_hdr_len( ssl ) ) )
5118 {
5119 MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake received (not HelloRequest)" ) );
5120
5121 /* With DTLS, drop the packet (probably from last handshake) */
5122 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5123 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
5124 {
5125 return( 0 );
5126 }
5127 #endif
5128 return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
5129 }
5130 #endif /* MBEDTLS_SSL_CLI_C */
5131
5132 #if defined(MBEDTLS_SSL_SRV_C)
5133 if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
5134 ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO )
5135 {
5136 MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake received (not ClientHello)" ) );
5137
5138 /* With DTLS, drop the packet (probably from last handshake) */
5139 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5140 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
5141 {
5142 return( 0 );
5143 }
5144 #endif
5145 return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
5146 }
5147 #endif /* MBEDTLS_SSL_SRV_C */
5148
5149 #if defined(MBEDTLS_SSL_RENEGOTIATION)
5150 /* Determine whether renegotiation attempt should be accepted */
5151 if( ! ( ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED ||
5152 ( ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION &&
5153 ssl->conf->allow_legacy_renegotiation ==
5154 MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION ) ) )
5155 {
5156 /*
5157 * Accept renegotiation request
5158 */
5159
5160 /* DTLS clients need to know renego is server-initiated */
5161 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5162 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
5163 ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
5164 {
5165 ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_PENDING;
5166 }
5167 #endif
5168 ret = mbedtls_ssl_start_renegotiation( ssl );
5169 if( ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
5170 ret != 0 )
5171 {
5172 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_start_renegotiation",
5173 ret );
5174 return( ret );
5175 }
5176 }
5177 else
5178 #endif /* MBEDTLS_SSL_RENEGOTIATION */
5179 {
5180 /*
5181 * Refuse renegotiation
5182 */
5183
5184 MBEDTLS_SSL_DEBUG_MSG( 3, ( "refusing renegotiation, sending alert" ) );
5185
5186 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
5187 if( ( ret = mbedtls_ssl_send_alert_message( ssl,
5188 MBEDTLS_SSL_ALERT_LEVEL_WARNING,
5189 MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION ) ) != 0 )
5190 {
5191 return( ret );
5192 }
5193 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
5194 }
5195
5196 return( 0 );
5197 }
5198
5199 /*
5200 * Receive application data decrypted from the SSL layer
5201 */
mbedtls_ssl_read(mbedtls_ssl_context * ssl,unsigned char * buf,size_t len)5202 int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
5203 {
5204 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
5205 size_t n;
5206
5207 if( ssl == NULL || ssl->conf == NULL )
5208 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
5209
5210 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> read" ) );
5211
5212 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5213 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
5214 {
5215 if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
5216 return( ret );
5217
5218 if( ssl->handshake != NULL &&
5219 ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
5220 {
5221 if( ( ret = mbedtls_ssl_flight_transmit( ssl ) ) != 0 )
5222 return( ret );
5223 }
5224 }
5225 #endif
5226
5227 /*
5228 * Check if renegotiation is necessary and/or handshake is
5229 * in process. If yes, perform/continue, and fall through
5230 * if an unexpected packet is received while the client
5231 * is waiting for the ServerHello.
5232 *
5233 * (There is no equivalent to the last condition on
5234 * the server-side as it is not treated as within
5235 * a handshake while waiting for the ClientHello
5236 * after a renegotiation request.)
5237 */
5238
5239 #if defined(MBEDTLS_SSL_RENEGOTIATION)
5240 ret = ssl_check_ctr_renegotiate( ssl );
5241 if( ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
5242 ret != 0 )
5243 {
5244 MBEDTLS_SSL_DEBUG_RET( 1, "ssl_check_ctr_renegotiate", ret );
5245 return( ret );
5246 }
5247 #endif
5248
5249 if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
5250 {
5251 ret = mbedtls_ssl_handshake( ssl );
5252 if( ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
5253 ret != 0 )
5254 {
5255 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
5256 return( ret );
5257 }
5258 }
5259
5260 /* Loop as long as no application data record is available */
5261 while( ssl->in_offt == NULL )
5262 {
5263 /* Start timer if not already running */
5264 if( ssl->f_get_timer != NULL &&
5265 ssl->f_get_timer( ssl->p_timer ) == -1 )
5266 {
5267 mbedtls_ssl_set_timer( ssl, ssl->conf->read_timeout );
5268 }
5269
5270 if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
5271 {
5272 if( ret == MBEDTLS_ERR_SSL_CONN_EOF )
5273 return( 0 );
5274
5275 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
5276 return( ret );
5277 }
5278
5279 if( ssl->in_msglen == 0 &&
5280 ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA )
5281 {
5282 /*
5283 * OpenSSL sends empty messages to randomize the IV
5284 */
5285 if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
5286 {
5287 if( ret == MBEDTLS_ERR_SSL_CONN_EOF )
5288 return( 0 );
5289
5290 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
5291 return( ret );
5292 }
5293 }
5294
5295 if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
5296 {
5297 ret = ssl_handle_hs_message_post_handshake( ssl );
5298 if( ret != 0)
5299 {
5300 MBEDTLS_SSL_DEBUG_RET( 1, "ssl_handle_hs_message_post_handshake",
5301 ret );
5302 return( ret );
5303 }
5304
5305 /* At this point, we don't know whether the renegotiation triggered
5306 * by the post-handshake message has been completed or not. The cases
5307 * to consider are the following:
5308 * 1) The renegotiation is complete. In this case, no new record
5309 * has been read yet.
5310 * 2) The renegotiation is incomplete because the client received
5311 * an application data record while awaiting the ServerHello.
5312 * 3) The renegotiation is incomplete because the client received
5313 * a non-handshake, non-application data message while awaiting
5314 * the ServerHello.
5315 *
5316 * In each of these cases, looping will be the proper action:
5317 * - For 1), the next iteration will read a new record and check
5318 * if it's application data.
5319 * - For 2), the loop condition isn't satisfied as application data
5320 * is present, hence continue is the same as break
5321 * - For 3), the loop condition is satisfied and read_record
5322 * will re-deliver the message that was held back by the client
5323 * when expecting the ServerHello.
5324 */
5325
5326 continue;
5327 }
5328 #if defined(MBEDTLS_SSL_RENEGOTIATION)
5329 else if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
5330 {
5331 if( ssl->conf->renego_max_records >= 0 )
5332 {
5333 if( ++ssl->renego_records_seen > ssl->conf->renego_max_records )
5334 {
5335 MBEDTLS_SSL_DEBUG_MSG( 1, ( "renegotiation requested, "
5336 "but not honored by client" ) );
5337 return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
5338 }
5339 }
5340 }
5341 #endif /* MBEDTLS_SSL_RENEGOTIATION */
5342
5343 /* Fatal and closure alerts handled by mbedtls_ssl_read_record() */
5344 if( ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT )
5345 {
5346 MBEDTLS_SSL_DEBUG_MSG( 2, ( "ignoring non-fatal non-closure alert" ) );
5347 return( MBEDTLS_ERR_SSL_WANT_READ );
5348 }
5349
5350 if( ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
5351 {
5352 MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad application data message" ) );
5353 return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
5354 }
5355
5356 ssl->in_offt = ssl->in_msg;
5357
5358 /* We're going to return something now, cancel timer,
5359 * except if handshake (renegotiation) is in progress */
5360 if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
5361 mbedtls_ssl_set_timer( ssl, 0 );
5362
5363 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5364 /* If we requested renego but received AppData, resend HelloRequest.
5365 * Do it now, after setting in_offt, to avoid taking this branch
5366 * again if ssl_write_hello_request() returns WANT_WRITE */
5367 #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
5368 if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
5369 ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
5370 {
5371 if( ( ret = mbedtls_ssl_resend_hello_request( ssl ) ) != 0 )
5372 {
5373 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend_hello_request",
5374 ret );
5375 return( ret );
5376 }
5377 }
5378 #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
5379 #endif /* MBEDTLS_SSL_PROTO_DTLS */
5380 }
5381
5382 n = ( len < ssl->in_msglen )
5383 ? len : ssl->in_msglen;
5384
5385 memcpy( buf, ssl->in_offt, n );
5386 ssl->in_msglen -= n;
5387
5388 /* Zeroising the plaintext buffer to erase unused application data
5389 from the memory. */
5390 mbedtls_platform_zeroize( ssl->in_offt, n );
5391
5392 if( ssl->in_msglen == 0 )
5393 {
5394 /* all bytes consumed */
5395 ssl->in_offt = NULL;
5396 ssl->keep_current_message = 0;
5397 }
5398 else
5399 {
5400 /* more data available */
5401 ssl->in_offt += n;
5402 }
5403
5404 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= read" ) );
5405
5406 return( (int) n );
5407 }
5408
5409 /*
5410 * Send application data to be encrypted by the SSL layer, taking care of max
5411 * fragment length and buffer size.
5412 *
5413 * According to RFC 5246 Section 6.2.1:
5414 *
5415 * Zero-length fragments of Application data MAY be sent as they are
5416 * potentially useful as a traffic analysis countermeasure.
5417 *
5418 * Therefore, it is possible that the input message length is 0 and the
5419 * corresponding return code is 0 on success.
5420 */
ssl_write_real(mbedtls_ssl_context * ssl,const unsigned char * buf,size_t len)5421 static int ssl_write_real( mbedtls_ssl_context *ssl,
5422 const unsigned char *buf, size_t len )
5423 {
5424 int ret = mbedtls_ssl_get_max_out_record_payload( ssl );
5425 const size_t max_len = (size_t) ret;
5426
5427 if( ret < 0 )
5428 {
5429 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_get_max_out_record_payload", ret );
5430 return( ret );
5431 }
5432
5433 if( len > max_len )
5434 {
5435 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5436 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
5437 {
5438 MBEDTLS_SSL_DEBUG_MSG( 1, ( "fragment larger than the (negotiated) "
5439 "maximum fragment length: %" MBEDTLS_PRINTF_SIZET
5440 " > %" MBEDTLS_PRINTF_SIZET,
5441 len, max_len ) );
5442 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
5443 }
5444 else
5445 #endif
5446 len = max_len;
5447 }
5448
5449 if( ssl->out_left != 0 )
5450 {
5451 /*
5452 * The user has previously tried to send the data and
5453 * MBEDTLS_ERR_SSL_WANT_WRITE or the message was only partially
5454 * written. In this case, we expect the high-level write function
5455 * (e.g. mbedtls_ssl_write()) to be called with the same parameters
5456 */
5457 if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
5458 {
5459 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flush_output", ret );
5460 return( ret );
5461 }
5462 }
5463 else
5464 {
5465 /*
5466 * The user is trying to send a message the first time, so we need to
5467 * copy the data into the internal buffers and setup the data structure
5468 * to keep track of partial writes
5469 */
5470 ssl->out_msglen = len;
5471 ssl->out_msgtype = MBEDTLS_SSL_MSG_APPLICATION_DATA;
5472 memcpy( ssl->out_msg, buf, len );
5473
5474 if( ( ret = mbedtls_ssl_write_record( ssl, SSL_FORCE_FLUSH ) ) != 0 )
5475 {
5476 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
5477 return( ret );
5478 }
5479 }
5480
5481 return( (int) len );
5482 }
5483
5484 /*
5485 * Write application data (public-facing wrapper)
5486 */
mbedtls_ssl_write(mbedtls_ssl_context * ssl,const unsigned char * buf,size_t len)5487 int mbedtls_ssl_write( mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len )
5488 {
5489 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
5490
5491 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write" ) );
5492
5493 if( ssl == NULL || ssl->conf == NULL )
5494 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
5495
5496 #if defined(MBEDTLS_SSL_RENEGOTIATION)
5497 if( ( ret = ssl_check_ctr_renegotiate( ssl ) ) != 0 )
5498 {
5499 MBEDTLS_SSL_DEBUG_RET( 1, "ssl_check_ctr_renegotiate", ret );
5500 return( ret );
5501 }
5502 #endif
5503
5504 if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
5505 {
5506 if( ( ret = mbedtls_ssl_handshake( ssl ) ) != 0 )
5507 {
5508 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
5509 return( ret );
5510 }
5511 }
5512
5513 ret = ssl_write_real( ssl, buf, len );
5514
5515 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write" ) );
5516
5517 return( ret );
5518 }
5519
5520 /*
5521 * Notify the peer that the connection is being closed
5522 */
mbedtls_ssl_close_notify(mbedtls_ssl_context * ssl)5523 int mbedtls_ssl_close_notify( mbedtls_ssl_context *ssl )
5524 {
5525 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
5526
5527 if( ssl == NULL || ssl->conf == NULL )
5528 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
5529
5530 MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write close notify" ) );
5531
5532 if( ssl->out_left != 0 )
5533 return( mbedtls_ssl_flush_output( ssl ) );
5534
5535 if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
5536 {
5537 if( ( ret = mbedtls_ssl_send_alert_message( ssl,
5538 MBEDTLS_SSL_ALERT_LEVEL_WARNING,
5539 MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY ) ) != 0 )
5540 {
5541 MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_send_alert_message", ret );
5542 return( ret );
5543 }
5544 }
5545
5546 MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write close notify" ) );
5547
5548 return( 0 );
5549 }
5550
mbedtls_ssl_transform_free(mbedtls_ssl_transform * transform)5551 void mbedtls_ssl_transform_free( mbedtls_ssl_transform *transform )
5552 {
5553 if( transform == NULL )
5554 return;
5555
5556 mbedtls_cipher_free( &transform->cipher_ctx_enc );
5557 mbedtls_cipher_free( &transform->cipher_ctx_dec );
5558
5559 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
5560 mbedtls_md_free( &transform->md_ctx_enc );
5561 mbedtls_md_free( &transform->md_ctx_dec );
5562 #endif
5563
5564 mbedtls_platform_zeroize( transform, sizeof( mbedtls_ssl_transform ) );
5565 }
5566
mbedtls_ssl_set_inbound_transform(mbedtls_ssl_context * ssl,mbedtls_ssl_transform * transform)5567 void mbedtls_ssl_set_inbound_transform( mbedtls_ssl_context *ssl,
5568 mbedtls_ssl_transform *transform )
5569 {
5570 ssl->transform_in = transform;
5571 memset( ssl->in_ctr, 0, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN );
5572 }
5573
mbedtls_ssl_set_outbound_transform(mbedtls_ssl_context * ssl,mbedtls_ssl_transform * transform)5574 void mbedtls_ssl_set_outbound_transform( mbedtls_ssl_context *ssl,
5575 mbedtls_ssl_transform *transform )
5576 {
5577 ssl->transform_out = transform;
5578 memset( ssl->cur_out_ctr, 0, sizeof( ssl->cur_out_ctr ) );
5579 }
5580
5581 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5582
mbedtls_ssl_buffering_free(mbedtls_ssl_context * ssl)5583 void mbedtls_ssl_buffering_free( mbedtls_ssl_context *ssl )
5584 {
5585 unsigned offset;
5586 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
5587
5588 if( hs == NULL )
5589 return;
5590
5591 ssl_free_buffered_record( ssl );
5592
5593 for( offset = 0; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++ )
5594 ssl_buffering_free_slot( ssl, offset );
5595 }
5596
ssl_buffering_free_slot(mbedtls_ssl_context * ssl,uint8_t slot)5597 static void ssl_buffering_free_slot( mbedtls_ssl_context *ssl,
5598 uint8_t slot )
5599 {
5600 mbedtls_ssl_handshake_params * const hs = ssl->handshake;
5601 mbedtls_ssl_hs_buffer * const hs_buf = &hs->buffering.hs[slot];
5602
5603 if( slot >= MBEDTLS_SSL_MAX_BUFFERED_HS )
5604 return;
5605
5606 if( hs_buf->is_valid == 1 )
5607 {
5608 hs->buffering.total_bytes_buffered -= hs_buf->data_len;
5609 mbedtls_platform_zeroize( hs_buf->data, hs_buf->data_len );
5610 mbedtls_free( hs_buf->data );
5611 memset( hs_buf, 0, sizeof( mbedtls_ssl_hs_buffer ) );
5612 }
5613 }
5614
5615 #endif /* MBEDTLS_SSL_PROTO_DTLS */
5616
5617 /*
5618 * Convert version numbers to/from wire format
5619 * and, for DTLS, to/from TLS equivalent.
5620 *
5621 * For TLS this is the identity.
5622 * For DTLS, use 1's complement (v -> 255 - v, and then map as follows:
5623 * 1.x <-> 3.x+1 for x != 0 (DTLS 1.2 based on TLS 1.2)
5624 */
mbedtls_ssl_write_version(int major,int minor,int transport,unsigned char ver[2])5625 void mbedtls_ssl_write_version( int major, int minor, int transport,
5626 unsigned char ver[2] )
5627 {
5628 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5629 if( transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
5630 {
5631 if( minor == MBEDTLS_SSL_MINOR_VERSION_2 )
5632 --minor; /* DTLS 1.0 stored as TLS 1.1 internally */
5633
5634 ver[0] = (unsigned char)( 255 - ( major - 2 ) );
5635 ver[1] = (unsigned char)( 255 - ( minor - 1 ) );
5636 }
5637 else
5638 #else
5639 ((void) transport);
5640 #endif
5641 {
5642 ver[0] = (unsigned char) major;
5643 ver[1] = (unsigned char) minor;
5644 }
5645 }
5646
mbedtls_ssl_read_version(int * major,int * minor,int transport,const unsigned char ver[2])5647 void mbedtls_ssl_read_version( int *major, int *minor, int transport,
5648 const unsigned char ver[2] )
5649 {
5650 #if defined(MBEDTLS_SSL_PROTO_DTLS)
5651 if( transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
5652 {
5653 *major = 255 - ver[0] + 2;
5654 *minor = 255 - ver[1] + 1;
5655
5656 if( *minor == MBEDTLS_SSL_MINOR_VERSION_1 )
5657 ++*minor; /* DTLS 1.0 stored as TLS 1.1 internally */
5658 }
5659 else
5660 #else
5661 ((void) transport);
5662 #endif
5663 {
5664 *major = ver[0];
5665 *minor = ver[1];
5666 }
5667 }
5668
5669 /*
5670 * Send pending fatal alert.
5671 * 0, No alert message.
5672 * !0, if mbedtls_ssl_send_alert_message() returned in error, the error code it
5673 * returned, ssl->alert_reason otherwise.
5674 */
mbedtls_ssl_handle_pending_alert(mbedtls_ssl_context * ssl)5675 int mbedtls_ssl_handle_pending_alert( mbedtls_ssl_context *ssl )
5676 {
5677 int ret;
5678
5679 /* No pending alert, return success*/
5680 if( ssl->send_alert == 0 )
5681 return( 0 );
5682
5683 ret = mbedtls_ssl_send_alert_message( ssl,
5684 MBEDTLS_SSL_ALERT_LEVEL_FATAL,
5685 ssl->alert_type );
5686
5687 /* If mbedtls_ssl_send_alert_message() returned with MBEDTLS_ERR_SSL_WANT_WRITE,
5688 * do not clear the alert to be able to send it later.
5689 */
5690 if( ret != MBEDTLS_ERR_SSL_WANT_WRITE )
5691 {
5692 ssl->send_alert = 0;
5693 }
5694
5695 if( ret != 0 )
5696 return( ret );
5697
5698 return( ssl->alert_reason );
5699 }
5700
5701 /*
5702 * Set pending fatal alert flag.
5703 */
mbedtls_ssl_pend_fatal_alert(mbedtls_ssl_context * ssl,unsigned char alert_type,int alert_reason)5704 void mbedtls_ssl_pend_fatal_alert( mbedtls_ssl_context *ssl,
5705 unsigned char alert_type,
5706 int alert_reason )
5707 {
5708 ssl->send_alert = 1;
5709 ssl->alert_type = alert_type;
5710 ssl->alert_reason = alert_reason;
5711 }
5712
5713 #endif /* MBEDTLS_SSL_TLS_C */
5714