cf1d2db628949995f21bf517ff5ef35370e15075
[BearSSL] / inc / bearssl_ssl.h
1 /*
2 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25 #ifndef BR_BEARSSL_SSL_H__
26 #define BR_BEARSSL_SSL_H__
27
28 #include <stddef.h>
29 #include <stdint.h>
30
31 #include "bearssl_block.h"
32 #include "bearssl_hash.h"
33 #include "bearssl_hmac.h"
34 #include "bearssl_prf.h"
35 #include "bearssl_rand.h"
36 #include "bearssl_x509.h"
37
38 /** \file bearssl_ssl.h
39 *
40 * # SSL
41 *
42 * For an overview of the SSL/TLS API, see [the BearSSL Web
43 * site](https://www.bearssl.org/api1.html).
44 *
45 * The `BR_TLS_*` constants correspond to the standard cipher suites and
46 * their values in the [IANA
47 * registry](http://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-4).
48 *
49 * The `BR_ALERT_*` constants are for standard TLS alert messages. When
50 * a fatal alert message is sent of received, then the SSL engine context
51 * status is set to the sum of that alert value (an integer in the 0..255
52 * range) and a fixed offset (`BR_ERR_SEND_FATAL_ALERT` for a sent alert,
53 * `BR_ERR_RECV_FATAL_ALERT` for a received alert).
54 */
55
56 /** \brief Optimal input buffer size. */
57 #define BR_SSL_BUFSIZE_INPUT (16384 + 325)
58
59 /** \brief Optimal output buffer size. */
60 #define BR_SSL_BUFSIZE_OUTPUT (16384 + 85)
61
62 /** \brief Optimal buffer size for monodirectional engine
63 (shared input/output buffer). */
64 #define BR_SSL_BUFSIZE_MONO BR_SSL_BUFSIZE_INPUT
65
66 /** \brief Optimal buffer size for bidirectional engine
67 (single buffer split into two separate input/output buffers). */
68 #define BR_SSL_BUFSIZE_BIDI (BR_SSL_BUFSIZE_INPUT + BR_SSL_BUFSIZE_OUTPUT)
69
70 /*
71 * Constants for known SSL/TLS protocol versions (SSL 3.0, TLS 1.0, TLS 1.1
72 * and TLS 1.2). Note that though there is a constant for SSL 3.0, that
73 * protocol version is not actually supported.
74 */
75
76 /** \brief Protocol version: SSL 3.0 (unsupported). */
77 #define BR_SSL30 0x0300
78 /** \brief Protocol version: TLS 1.0. */
79 #define BR_TLS10 0x0301
80 /** \brief Protocol version: TLS 1.1. */
81 #define BR_TLS11 0x0302
82 /** \brief Protocol version: TLS 1.2. */
83 #define BR_TLS12 0x0303
84
85 /*
86 * Error constants. They are used to report the reason why a context has
87 * been marked as failed.
88 *
89 * Implementation note: SSL-level error codes should be in the 1..31
90 * range. The 32..63 range is for certificate decoding and validation
91 * errors. Received fatal alerts imply an error code in the 256..511 range.
92 */
93
94 /** \brief SSL status: no error so far (0). */
95 #define BR_ERR_OK 0
96
97 /** \brief SSL status: caller-provided parameter is incorrect. */
98 #define BR_ERR_BAD_PARAM 1
99
100 /** \brief SSL status: operation requested by the caller cannot be applied
101 with the current context state (e.g. reading data while outgoing data
102 is waiting to be sent). */
103 #define BR_ERR_BAD_STATE 2
104
105 /** \brief SSL status: incoming protocol or record version is unsupported. */
106 #define BR_ERR_UNSUPPORTED_VERSION 3
107
108 /** \brief SSL status: incoming record version does not match the expected
109 version. */
110 #define BR_ERR_BAD_VERSION 4
111
112 /** \brief SSL status: incoming record length is invalid. */
113 #define BR_ERR_BAD_LENGTH 5
114
115 /** \brief SSL status: incoming record is too large to be processed, or
116 buffer is too small for the handshake message to send. */
117 #define BR_ERR_TOO_LARGE 6
118
119 /** \brief SSL status: decryption found an invalid padding, or the record
120 MAC is not correct. */
121 #define BR_ERR_BAD_MAC 7
122
123 /** \brief SSL status: no initial entropy was provided, and none can be
124 obtained from the OS. */
125 #define BR_ERR_NO_RANDOM 8
126
127 /** \brief SSL status: incoming record type is unknown. */
128 #define BR_ERR_UNKNOWN_TYPE 9
129
130 /** \brief SSL status: incoming record or message has wrong type with
131 regards to the current engine state. */
132 #define BR_ERR_UNEXPECTED 10
133
134 /** \brief SSL status: ChangeCipherSpec message from the peer has invalid
135 contents. */
136 #define BR_ERR_BAD_CCS 12
137
138 /** \brief SSL status: alert message from the peer has invalid contents
139 (odd length). */
140 #define BR_ERR_BAD_ALERT 13
141
142 /** \brief SSL status: incoming handshake message decoding failed. */
143 #define BR_ERR_BAD_HANDSHAKE 14
144
145 /** \brief SSL status: ServerHello contains a session ID which is larger
146 than 32 bytes. */
147 #define BR_ERR_OVERSIZED_ID 15
148
149 /** \brief SSL status: server wants to use a cipher suite that we did
150 not claim to support. This is also reported if we tried to advertise
151 a cipher suite that we do not support. */
152 #define BR_ERR_BAD_CIPHER_SUITE 16
153
154 /** \brief SSL status: server wants to use a compression that we did not
155 claim to support. */
156 #define BR_ERR_BAD_COMPRESSION 17
157
158 /** \brief SSL status: server's max fragment length does not match
159 client's. */
160 #define BR_ERR_BAD_FRAGLEN 18
161
162 /** \brief SSL status: secure renegotiation failed. */
163 #define BR_ERR_BAD_SECRENEG 19
164
165 /** \brief SSL status: server sent an extension type that we did not
166 announce, or used the same extension type several times in a single
167 ServerHello. */
168 #define BR_ERR_EXTRA_EXTENSION 20
169
170 /** \brief SSL status: invalid Server Name Indication contents (when
171 used by the server, this extension shall be empty). */
172 #define BR_ERR_BAD_SNI 21
173
174 /** \brief SSL status: invalid ServerHelloDone from the server (length
175 is not 0). */
176 #define BR_ERR_BAD_HELLO_DONE 22
177
178 /** \brief SSL status: internal limit exceeded (e.g. server's public key
179 is too large). */
180 #define BR_ERR_LIMIT_EXCEEDED 23
181
182 /** \brief SSL status: Finished message from peer does not match the
183 expected value. */
184 #define BR_ERR_BAD_FINISHED 24
185
186 /** \brief SSL status: session resumption attempt with distinct version
187 or cipher suite. */
188 #define BR_ERR_RESUME_MISMATCH 25
189
190 /** \brief SSL status: unsupported or invalid algorithm (ECDHE curve,
191 signature algorithm, hash function). */
192 #define BR_ERR_INVALID_ALGORITHM 26
193
194 /** \brief SSL status: invalid signature (on ServerKeyExchange from
195 server, or in CertificateVerify from client). */
196 #define BR_ERR_BAD_SIGNATURE 27
197
198 /** \brief SSL status: peer's public key does not have the proper type
199 or is not allowed for requested operation. */
200 #define BR_ERR_WRONG_KEY_USAGE 28
201
202 /** \brief SSL status: client did not send a certificate upon request,
203 or the client certificate could not be validated. */
204 #define BR_ERR_NO_CLIENT_AUTH 29
205
206 /** \brief SSL status: I/O error or premature close on underlying
207 transport stream. This error code is set only by the simplified
208 I/O API ("br_sslio_*"). */
209 #define BR_ERR_IO 31
210
211 /** \brief SSL status: base value for a received fatal alert.
212
213 When a fatal alert is received from the peer, the alert value
214 is added to this constant. */
215 #define BR_ERR_RECV_FATAL_ALERT 256
216
217 /** \brief SSL status: base value for a sent fatal alert.
218
219 When a fatal alert is sent to the peer, the alert value is added
220 to this constant. */
221 #define BR_ERR_SEND_FATAL_ALERT 512
222
223 /* ===================================================================== */
224
225 /**
226 * \brief Decryption engine for SSL.
227 *
228 * When processing incoming records, the SSL engine will use a decryption
229 * engine that uses a specific context structure, and has a set of
230 * methods (a vtable) that follows this template.
231 *
232 * The decryption engine is responsible for applying decryption, verifying
233 * MAC, and keeping track of the record sequence number.
234 */
235 typedef struct br_sslrec_in_class_ br_sslrec_in_class;
236 struct br_sslrec_in_class_ {
237 /**
238 * \brief Context size (in bytes).
239 */
240 size_t context_size;
241
242 /**
243 * \brief Test validity of the incoming record length.
244 *
245 * This function returns 1 if the announced length for an
246 * incoming record is valid, 0 otherwise,
247 *
248 * \param ctx decryption engine context.
249 * \param record_len incoming record length.
250 * \return 1 of a valid length, 0 otherwise.
251 */
252 int (*check_length)(const br_sslrec_in_class *const *ctx,
253 size_t record_len);
254
255 /**
256 * \brief Decrypt the incoming record.
257 *
258 * This function may assume that the record length is valid
259 * (it has been previously tested with `check_length()`).
260 * Decryption is done in place; `*len` is updated with the
261 * cleartext length, and the address of the first plaintext
262 * byte is returned. If the record is correct but empty, then
263 * `*len` is set to 0 and a non-`NULL` pointer is returned.
264 *
265 * On decryption/MAC error, `NULL` is returned.
266 *
267 * \param ctx decryption engine context.
268 * \param record_type record type (23 for application data, etc).
269 * \param version record version.
270 * \param payload address of encrypted payload.
271 * \param len pointer to payload length (updated).
272 * \return pointer to plaintext, or `NULL` on error.
273 */
274 unsigned char *(*decrypt)(const br_sslrec_in_class **ctx,
275 int record_type, unsigned version,
276 void *payload, size_t *len);
277 };
278
279 /**
280 * \brief Encryption engine for SSL.
281 *
282 * When building outgoing records, the SSL engine will use an encryption
283 * engine that uses a specific context structure, and has a set of
284 * methods (a vtable) that follows this template.
285 *
286 * The encryption engine is responsible for applying encryption and MAC,
287 * and keeping track of the record sequence number.
288 */
289 typedef struct br_sslrec_out_class_ br_sslrec_out_class;
290 struct br_sslrec_out_class_ {
291 /**
292 * \brief Context size (in bytes).
293 */
294 size_t context_size;
295
296 /**
297 * \brief Compute maximum plaintext sizes and offsets.
298 *
299 * When this function is called, the `*start` and `*end`
300 * values contain offsets designating the free area in the
301 * outgoing buffer for plaintext data; that free area is
302 * preceded by a 5-byte space which will receive the record
303 * header.
304 *
305 * The `max_plaintext()` function is responsible for adjusting
306 * both `*start` and `*end` to make room for any record-specific
307 * header, MAC, padding, and possible split.
308 *
309 * \param ctx encryption engine context.
310 * \param start pointer to start of plaintext offset (updated).
311 * \param end pointer to start of plaintext offset (updated).
312 */
313 void (*max_plaintext)(const br_sslrec_out_class *const *ctx,
314 size_t *start, size_t *end);
315
316 /**
317 * \brief Perform record encryption.
318 *
319 * This function encrypts the record. The plaintext address and
320 * length are provided. Returned value is the start of the
321 * encrypted record (or sequence of records, if a split was
322 * performed), _including_ the 5-byte header, and `*len` is
323 * adjusted to the total size of the record(s), there again
324 * including the header(s).
325 *
326 * \param ctx decryption engine context.
327 * \param record_type record type (23 for application data, etc).
328 * \param version record version.
329 * \param plaintext address of plaintext.
330 * \param len pointer to plaintext length (updated).
331 * \return pointer to start of built record.
332 */
333 unsigned char *(*encrypt)(const br_sslrec_out_class **ctx,
334 int record_type, unsigned version,
335 void *plaintext, size_t *len);
336 };
337
338 /**
339 * \brief Context for a no-encryption engine.
340 *
341 * The no-encryption engine processes outgoing records during the initial
342 * handshake, before encryption is applied.
343 */
344 typedef struct {
345 /** \brief No-encryption engine vtable. */
346 const br_sslrec_out_class *vtable;
347 } br_sslrec_out_clear_context;
348
349 /** \brief Static, constant vtable for the no-encryption engine. */
350 extern const br_sslrec_out_class br_sslrec_out_clear_vtable;
351
352 /* ===================================================================== */
353
354 /**
355 * \brief Record decryption engine class, for CBC mode.
356 *
357 * This class type extends the decryption engine class with an
358 * initialisation method that receives the parameters needed
359 * for CBC processing: block cipher implementation, block cipher key,
360 * HMAC parameters (hash function, key, MAC length), and IV. If the
361 * IV is `NULL`, then a per-record IV will be used (TLS 1.1+).
362 */
363 typedef struct br_sslrec_in_cbc_class_ br_sslrec_in_cbc_class;
364 struct br_sslrec_in_cbc_class_ {
365 /**
366 * \brief Superclass, as first vtable field.
367 */
368 br_sslrec_in_class inner;
369
370 /**
371 * \brief Engine initialisation method.
372 *
373 * This method sets the vtable field in the context.
374 *
375 * \param ctx context to initialise.
376 * \param bc_impl block cipher implementation (CBC decryption).
377 * \param bc_key block cipher key.
378 * \param bc_key_len block cipher key length (in bytes).
379 * \param dig_impl hash function for HMAC.
380 * \param mac_key HMAC key.
381 * \param mac_key_len HMAC key length (in bytes).
382 * \param mac_out_len HMAC output length (in bytes).
383 * \param iv initial IV (or `NULL`).
384 */
385 void (*init)(const br_sslrec_in_cbc_class **ctx,
386 const br_block_cbcdec_class *bc_impl,
387 const void *bc_key, size_t bc_key_len,
388 const br_hash_class *dig_impl,
389 const void *mac_key, size_t mac_key_len, size_t mac_out_len,
390 const void *iv);
391 };
392
393 /**
394 * \brief Record encryption engine class, for CBC mode.
395 *
396 * This class type extends the encryption engine class with an
397 * initialisation method that receives the parameters needed
398 * for CBC processing: block cipher implementation, block cipher key,
399 * HMAC parameters (hash function, key, MAC length), and IV. If the
400 * IV is `NULL`, then a per-record IV will be used (TLS 1.1+).
401 */
402 typedef struct br_sslrec_out_cbc_class_ br_sslrec_out_cbc_class;
403 struct br_sslrec_out_cbc_class_ {
404 /**
405 * \brief Superclass, as first vtable field.
406 */
407 br_sslrec_out_class inner;
408
409 /**
410 * \brief Engine initialisation method.
411 *
412 * This method sets the vtable field in the context.
413 *
414 * \param ctx context to initialise.
415 * \param bc_impl block cipher implementation (CBC encryption).
416 * \param bc_key block cipher key.
417 * \param bc_key_len block cipher key length (in bytes).
418 * \param dig_impl hash function for HMAC.
419 * \param mac_key HMAC key.
420 * \param mac_key_len HMAC key length (in bytes).
421 * \param mac_out_len HMAC output length (in bytes).
422 * \param iv initial IV (or `NULL`).
423 */
424 void (*init)(const br_sslrec_out_cbc_class **ctx,
425 const br_block_cbcenc_class *bc_impl,
426 const void *bc_key, size_t bc_key_len,
427 const br_hash_class *dig_impl,
428 const void *mac_key, size_t mac_key_len, size_t mac_out_len,
429 const void *iv);
430 };
431
432 /**
433 * \brief Context structure for decrypting incoming records with
434 * CBC + HMAC.
435 *
436 * The first field points to the vtable. The other fields are opaque
437 * and shall not be accessed directly.
438 */
439 typedef struct {
440 /** \brief Pointer to vtable. */
441 const br_sslrec_in_cbc_class *vtable;
442 #ifndef BR_DOXYGEN_IGNORE
443 uint64_t seq;
444 union {
445 const br_block_cbcdec_class *vtable;
446 br_aes_gen_cbcdec_keys aes;
447 br_des_gen_cbcdec_keys des;
448 } bc;
449 br_hmac_key_context mac;
450 size_t mac_len;
451 unsigned char iv[16];
452 int explicit_IV;
453 #endif
454 } br_sslrec_in_cbc_context;
455
456 /**
457 * \brief Static, constant vtable for record decryption with CBC.
458 */
459 extern const br_sslrec_in_cbc_class br_sslrec_in_cbc_vtable;
460
461 /**
462 * \brief Context structure for encrypting outgoing records with
463 * CBC + HMAC.
464 *
465 * The first field points to the vtable. The other fields are opaque
466 * and shall not be accessed directly.
467 */
468 typedef struct {
469 /** \brief Pointer to vtable. */
470 const br_sslrec_out_cbc_class *vtable;
471 #ifndef BR_DOXYGEN_IGNORE
472 uint64_t seq;
473 union {
474 const br_block_cbcenc_class *vtable;
475 br_aes_gen_cbcenc_keys aes;
476 br_des_gen_cbcenc_keys des;
477 } bc;
478 br_hmac_key_context mac;
479 size_t mac_len;
480 unsigned char iv[16];
481 int explicit_IV;
482 #endif
483 } br_sslrec_out_cbc_context;
484
485 /**
486 * \brief Static, constant vtable for record encryption with CBC.
487 */
488 extern const br_sslrec_out_cbc_class br_sslrec_out_cbc_vtable;
489
490 /* ===================================================================== */
491
492 /**
493 * \brief Record decryption engine class, for GCM mode.
494 *
495 * This class type extends the decryption engine class with an
496 * initialisation method that receives the parameters needed
497 * for GCM processing: block cipher implementation, block cipher key,
498 * GHASH implementation, and 4-byte IV.
499 */
500 typedef struct br_sslrec_in_gcm_class_ br_sslrec_in_gcm_class;
501 struct br_sslrec_in_gcm_class_ {
502 /**
503 * \brief Superclass, as first vtable field.
504 */
505 br_sslrec_in_class inner;
506
507 /**
508 * \brief Engine initialisation method.
509 *
510 * This method sets the vtable field in the context.
511 *
512 * \param ctx context to initialise.
513 * \param bc_impl block cipher implementation (CTR).
514 * \param key block cipher key.
515 * \param key_len block cipher key length (in bytes).
516 * \param gh_impl GHASH implementation.
517 * \param iv static IV (4 bytes).
518 */
519 void (*init)(const br_sslrec_in_gcm_class **ctx,
520 const br_block_ctr_class *bc_impl,
521 const void *key, size_t key_len,
522 br_ghash gh_impl,
523 const void *iv);
524 };
525
526 /**
527 * \brief Record encryption engine class, for GCM mode.
528 *
529 * This class type extends the encryption engine class with an
530 * initialisation method that receives the parameters needed
531 * for GCM processing: block cipher implementation, block cipher key,
532 * GHASH implementation, and 4-byte IV.
533 */
534 typedef struct br_sslrec_out_gcm_class_ br_sslrec_out_gcm_class;
535 struct br_sslrec_out_gcm_class_ {
536 /**
537 * \brief Superclass, as first vtable field.
538 */
539 br_sslrec_out_class inner;
540
541 /**
542 * \brief Engine initialisation method.
543 *
544 * This method sets the vtable field in the context.
545 *
546 * \param ctx context to initialise.
547 * \param bc_impl block cipher implementation (CTR).
548 * \param key block cipher key.
549 * \param key_len block cipher key length (in bytes).
550 * \param gh_impl GHASH implementation.
551 * \param iv static IV (4 bytes).
552 */
553 void (*init)(const br_sslrec_out_gcm_class **ctx,
554 const br_block_ctr_class *bc_impl,
555 const void *key, size_t key_len,
556 br_ghash gh_impl,
557 const void *iv);
558 };
559
560 /**
561 * \brief Context structure for processing records with GCM.
562 *
563 * The same context structure is used for encrypting and decrypting.
564 *
565 * The first field points to the vtable. The other fields are opaque
566 * and shall not be accessed directly.
567 */
568 typedef struct {
569 /** \brief Pointer to vtable. */
570 union {
571 const void *gen;
572 const br_sslrec_in_gcm_class *in;
573 const br_sslrec_out_gcm_class *out;
574 } vtable;
575 #ifndef BR_DOXYGEN_IGNORE
576 uint64_t seq;
577 union {
578 const br_block_ctr_class *vtable;
579 br_aes_gen_ctr_keys aes;
580 } bc;
581 br_ghash gh;
582 unsigned char iv[4];
583 unsigned char h[16];
584 #endif
585 } br_sslrec_gcm_context;
586
587 /**
588 * \brief Static, constant vtable for record decryption with GCM.
589 */
590 extern const br_sslrec_in_gcm_class br_sslrec_in_gcm_vtable;
591
592 /**
593 * \brief Static, constant vtable for record encryption with GCM.
594 */
595 extern const br_sslrec_out_gcm_class br_sslrec_out_gcm_vtable;
596
597 /* ===================================================================== */
598
599 /**
600 * \brief Record decryption engine class, for ChaCha20+Poly1305.
601 *
602 * This class type extends the decryption engine class with an
603 * initialisation method that receives the parameters needed
604 * for ChaCha20+Poly1305 processing: ChaCha20 implementation,
605 * Poly1305 implementation, key, and 12-byte IV.
606 */
607 typedef struct br_sslrec_in_chapol_class_ br_sslrec_in_chapol_class;
608 struct br_sslrec_in_chapol_class_ {
609 /**
610 * \brief Superclass, as first vtable field.
611 */
612 br_sslrec_in_class inner;
613
614 /**
615 * \brief Engine initialisation method.
616 *
617 * This method sets the vtable field in the context.
618 *
619 * \param ctx context to initialise.
620 * \param ichacha ChaCha20 implementation.
621 * \param ipoly Poly1305 implementation.
622 * \param key secret key (32 bytes).
623 * \param iv static IV (12 bytes).
624 */
625 void (*init)(const br_sslrec_in_chapol_class **ctx,
626 br_chacha20_run ichacha,
627 br_poly1305_run ipoly,
628 const void *key, const void *iv);
629 };
630
631 /**
632 * \brief Record encryption engine class, for ChaCha20+Poly1305.
633 *
634 * This class type extends the encryption engine class with an
635 * initialisation method that receives the parameters needed
636 * for ChaCha20+Poly1305 processing: ChaCha20 implementation,
637 * Poly1305 implementation, key, and 12-byte IV.
638 */
639 typedef struct br_sslrec_out_chapol_class_ br_sslrec_out_chapol_class;
640 struct br_sslrec_out_chapol_class_ {
641 /**
642 * \brief Superclass, as first vtable field.
643 */
644 br_sslrec_out_class inner;
645
646 /**
647 * \brief Engine initialisation method.
648 *
649 * This method sets the vtable field in the context.
650 *
651 * \param ctx context to initialise.
652 * \param ichacha ChaCha20 implementation.
653 * \param ipoly Poly1305 implementation.
654 * \param key secret key (32 bytes).
655 * \param iv static IV (12 bytes).
656 */
657 void (*init)(const br_sslrec_out_chapol_class **ctx,
658 br_chacha20_run ichacha,
659 br_poly1305_run ipoly,
660 const void *key, const void *iv);
661 };
662
663 /**
664 * \brief Context structure for processing records with ChaCha20+Poly1305.
665 *
666 * The same context structure is used for encrypting and decrypting.
667 *
668 * The first field points to the vtable. The other fields are opaque
669 * and shall not be accessed directly.
670 */
671 typedef struct {
672 /** \brief Pointer to vtable. */
673 union {
674 const void *gen;
675 const br_sslrec_in_chapol_class *in;
676 const br_sslrec_out_chapol_class *out;
677 } vtable;
678 #ifndef BR_DOXYGEN_IGNORE
679 uint64_t seq;
680 unsigned char key[32];
681 unsigned char iv[12];
682 br_chacha20_run ichacha;
683 br_poly1305_run ipoly;
684 #endif
685 } br_sslrec_chapol_context;
686
687 /**
688 * \brief Static, constant vtable for record decryption with ChaCha20+Poly1305.
689 */
690 extern const br_sslrec_in_chapol_class br_sslrec_in_chapol_vtable;
691
692 /**
693 * \brief Static, constant vtable for record encryption with ChaCha20+Poly1305.
694 */
695 extern const br_sslrec_out_chapol_class br_sslrec_out_chapol_vtable;
696
697 /* ===================================================================== */
698
699 /**
700 * \brief Type for session parameters, to be saved for session resumption.
701 */
702 typedef struct {
703 /** \brief Session ID buffer. */
704 unsigned char session_id[32];
705 /** \brief Session ID length (in bytes, at most 32). */
706 unsigned char session_id_len;
707 /** \brief Protocol version. */
708 uint16_t version;
709 /** \brief Cipher suite. */
710 uint16_t cipher_suite;
711 /** \brief Master secret. */
712 unsigned char master_secret[48];
713 } br_ssl_session_parameters;
714
715 #ifndef BR_DOXYGEN_IGNORE
716 /*
717 * Maximum numnber of cipher suites supported by a client or server.
718 */
719 #define BR_MAX_CIPHER_SUITES 40
720 #endif
721
722 /**
723 * \brief Context structure for SSL engine.
724 *
725 * This strucuture is common to the client and server; both the client
726 * context (`br_ssl_client_context`) and the server context
727 * (`br_ssl_server_context`) include a `br_ssl_engine_context` as their
728 * first field.
729 *
730 * The engine context manages records, including alerts, closures, and
731 * transitions to new encryption/MAC algorithms. Processing of handshake
732 * records is delegated to externally provided code. This structure
733 * should not be used directly.
734 *
735 * Structure contents are opaque and shall not be accessed directly.
736 */
737 typedef struct {
738 #ifndef BR_DOXYGEN_IGNORE
739 /*
740 * The error code. When non-zero, then the state is "failed" and
741 * no I/O may occur until reset.
742 */
743 int err;
744
745 /*
746 * Configured I/O buffers. They are either disjoint, or identical.
747 */
748 unsigned char *ibuf, *obuf;
749 size_t ibuf_len, obuf_len;
750
751 /*
752 * Maximum fragment length applies to outgoing records; incoming
753 * records can be processed as long as they fit in the input
754 * buffer. It is guaranteed that incoming records at least as big
755 * as max_frag_len can be processed.
756 */
757 uint16_t max_frag_len;
758 unsigned char log_max_frag_len;
759 unsigned char peer_log_max_frag_len;
760
761 /*
762 * Buffering management registers.
763 */
764 size_t ixa, ixb, ixc;
765 size_t oxa, oxb, oxc;
766 unsigned char iomode;
767 unsigned char incrypt;
768
769 /*
770 * Shutdown flag: when set to non-zero, incoming record bytes
771 * will not be accepted anymore. This is used after a close_notify
772 * has been received: afterwards, the engine no longer claims that
773 * it could receive bytes from the transport medium.
774 */
775 unsigned char shutdown_recv;
776
777 /*
778 * 'record_type_in' is set to the incoming record type when the
779 * record header has been received.
780 * 'record_type_out' is used to make the next outgoing record
781 * header when it is ready to go.
782 */
783 unsigned char record_type_in, record_type_out;
784
785 /*
786 * When a record is received, its version is extracted:
787 * -- if 'version_in' is 0, then it is set to the received version;
788 * -- otherwise, if the received version is not identical to
789 * the 'version_in' contents, then a failure is reported.
790 *
791 * This implements the SSL requirement that all records shall
792 * use the negotiated protocol version, once decided (in the
793 * ServerHello). It is up to the handshake handler to adjust this
794 * field when necessary.
795 */
796 uint16_t version_in;
797
798 /*
799 * 'version_out' is used when the next outgoing record is ready
800 * to go.
801 */
802 uint16_t version_out;
803
804 /*
805 * Record handler contexts.
806 */
807 union {
808 const br_sslrec_in_class *vtable;
809 br_sslrec_in_cbc_context cbc;
810 br_sslrec_gcm_context gcm;
811 br_sslrec_chapol_context chapol;
812 } in;
813 union {
814 const br_sslrec_out_class *vtable;
815 br_sslrec_out_clear_context clear;
816 br_sslrec_out_cbc_context cbc;
817 br_sslrec_gcm_context gcm;
818 br_sslrec_chapol_context chapol;
819 } out;
820
821 /*
822 * The "application data" flag. It is set when application data
823 * can be exchanged, cleared otherwise.
824 */
825 unsigned char application_data;
826
827 /*
828 * Context RNG.
829 */
830 br_hmac_drbg_context rng;
831 int rng_init_done;
832 int rng_os_rand_done;
833
834 /*
835 * Supported minimum and maximum versions, and cipher suites.
836 */
837 uint16_t version_min;
838 uint16_t version_max;
839 uint16_t suites_buf[BR_MAX_CIPHER_SUITES];
840 unsigned char suites_num;
841
842 /*
843 * For clients, the server name to send as a SNI extension. For
844 * servers, the name received in the SNI extension (if any).
845 */
846 char server_name[256];
847
848 /*
849 * "Security parameters". These are filled by the handshake
850 * handler, and used when switching encryption state.
851 */
852 unsigned char client_random[32];
853 unsigned char server_random[32];
854 br_ssl_session_parameters session;
855
856 /*
857 * ECDHE elements: curve and point from the peer. The server also
858 * uses that buffer for the point to send to the client.
859 */
860 unsigned char ecdhe_curve;
861 unsigned char ecdhe_point[133];
862 unsigned char ecdhe_point_len;
863
864 /*
865 * Secure renegotiation (RFC 5746): 'reneg' can be:
866 * 0 first handshake (server support is not known)
867 * 1 server does not support secure renegotiation
868 * 2 server supports secure renegotiation
869 *
870 * The saved_finished buffer contains the client and the
871 * server "Finished" values from the last handshake, in
872 * that order (12 bytes each).
873 */
874 unsigned char reneg;
875 unsigned char saved_finished[24];
876
877 /*
878 * Behavioural flags.
879 */
880 uint32_t flags;
881
882 /*
883 * Context variables for the handshake processor. The 'pad' must
884 * be large enough to accommodate an RSA-encrypted pre-master
885 * secret, or an RSA signature; since we want to support up to
886 * RSA-4096, this means at least 512 bytes. (Other pad usages
887 * require its length to be at least 256.)
888 */
889 struct {
890 uint32_t *dp;
891 uint32_t *rp;
892 const unsigned char *ip;
893 } cpu;
894 uint32_t dp_stack[32];
895 uint32_t rp_stack[32];
896 unsigned char pad[512];
897 unsigned char *hbuf_in, *hbuf_out, *saved_hbuf_out;
898 size_t hlen_in, hlen_out;
899 void (*hsrun)(void *ctx);
900
901 /*
902 * The 'action' value communicates OOB information between the
903 * engine and the handshake processor.
904 *
905 * From the engine:
906 * 0 invocation triggered by I/O
907 * 1 invocation triggered by explicit close
908 * 2 invocation triggered by explicit renegotiation
909 */
910 unsigned char action;
911
912 /*
913 * State for alert messages. Value is either 0, or the value of
914 * the alert level byte (level is either 1 for warning, or 2 for
915 * fatal; we convert all other values to 'fatal').
916 */
917 unsigned char alert;
918
919 /*
920 * Closure flags. This flag is set when a close_notify has been
921 * received from the peer.
922 */
923 unsigned char close_received;
924
925 /*
926 * Multi-hasher for the handshake messages. The handshake handler
927 * is responsible for resetting it when appropriate.
928 */
929 br_multihash_context mhash;
930
931 /*
932 * Pointer to the X.509 engine. The engine is supposed to be
933 * already initialized. It is used to validate the peer's
934 * certificate.
935 */
936 const br_x509_class **x509ctx;
937
938 /*
939 * Certificate chain to send. This is used by both client and
940 * server, when they send their respective Certificate messages.
941 * If chain_len is 0, then chain may be NULL.
942 */
943 const br_x509_certificate *chain;
944 size_t chain_len;
945 const unsigned char *cert_cur;
946 size_t cert_len;
947
948 /*
949 * List of supported protocol names (ALPN extension). If unset,
950 * (number of names is 0), then:
951 * - the client sends no ALPN extension;
952 * - the server ignores any incoming ALPN extension.
953 *
954 * Otherwise:
955 * - the client sends an ALPN extension with all the names;
956 * - the server selects the first protocol in its list that
957 * the client also supports, or fails (fatal alert 120)
958 * if the client sends an ALPN extension and there is no
959 * match.
960 *
961 * The 'selected_protocol' field contains 1+n if the matching
962 * name has index n in the list (the value is 0 if no match was
963 * performed, e.g. the peer did not send an ALPN extension).
964 */
965 const char **protocol_names;
966 uint16_t protocol_names_num;
967 uint16_t selected_protocol;
968
969 /*
970 * Pointers to implementations; left to NULL for unsupported
971 * functions. For the raw hash functions, implementations are
972 * referenced from the multihasher (mhash field).
973 */
974 br_tls_prf_impl prf10;
975 br_tls_prf_impl prf_sha256;
976 br_tls_prf_impl prf_sha384;
977 const br_block_cbcenc_class *iaes_cbcenc;
978 const br_block_cbcdec_class *iaes_cbcdec;
979 const br_block_ctr_class *iaes_ctr;
980 const br_block_cbcenc_class *ides_cbcenc;
981 const br_block_cbcdec_class *ides_cbcdec;
982 br_ghash ighash;
983 br_chacha20_run ichacha;
984 br_poly1305_run ipoly;
985 const br_sslrec_in_cbc_class *icbc_in;
986 const br_sslrec_out_cbc_class *icbc_out;
987 const br_sslrec_in_gcm_class *igcm_in;
988 const br_sslrec_out_gcm_class *igcm_out;
989 const br_sslrec_in_chapol_class *ichapol_in;
990 const br_sslrec_out_chapol_class *ichapol_out;
991 const br_ec_impl *iec;
992 br_rsa_pkcs1_vrfy irsavrfy;
993 br_ecdsa_vrfy iecdsa;
994 #endif
995 } br_ssl_engine_context;
996
997 /**
998 * \brief Get currently defined engine behavioural flags.
999 *
1000 * \param cc SSL engine context.
1001 * \return the flags.
1002 */
1003 static inline uint32_t
1004 br_ssl_engine_get_flags(br_ssl_engine_context *cc)
1005 {
1006 return cc->flags;
1007 }
1008
1009 /**
1010 * \brief Set all engine behavioural flags.
1011 *
1012 * \param cc SSL engine context.
1013 * \param flags new value for all flags.
1014 */
1015 static inline void
1016 br_ssl_engine_set_all_flags(br_ssl_engine_context *cc, uint32_t flags)
1017 {
1018 cc->flags = flags;
1019 }
1020
1021 /**
1022 * \brief Set some engine behavioural flags.
1023 *
1024 * The flags set in the `flags` parameter are set in the context; other
1025 * flags are untouched.
1026 *
1027 * \param cc SSL engine context.
1028 * \param flags additional set flags.
1029 */
1030 static inline void
1031 br_ssl_engine_add_flags(br_ssl_engine_context *cc, uint32_t flags)
1032 {
1033 cc->flags |= flags;
1034 }
1035
1036 /**
1037 * \brief Clear some engine behavioural flags.
1038 *
1039 * The flags set in the `flags` parameter are cleared from the context; other
1040 * flags are untouched.
1041 *
1042 * \param cc SSL engine context.
1043 * \param flags flags to remove.
1044 */
1045 static inline void
1046 br_ssl_engine_remove_flags(br_ssl_engine_context *cc, uint32_t flags)
1047 {
1048 cc->flags &= ~flags;
1049 }
1050
1051 /**
1052 * \brief Behavioural flag: enforce server preferences.
1053 *
1054 * If this flag is set, then the server will enforce its own cipher suite
1055 * preference order; otherwise, it follows the client preferences.
1056 */
1057 #define BR_OPT_ENFORCE_SERVER_PREFERENCES ((uint32_t)1 << 0)
1058
1059 /**
1060 * \brief Behavioural flag: disable renegotiation.
1061 *
1062 * If this flag is set, then renegotiations are rejected unconditionally:
1063 * they won't be honoured if asked for programmatically, and requests from
1064 * the peer are rejected.
1065 */
1066 #define BR_OPT_NO_RENEGOTIATION ((uint32_t)1 << 1)
1067
1068 /**
1069 * \brief Behavioural flag: tolerate lack of client authentication.
1070 *
1071 * If this flag is set in a server and the server requests a client
1072 * certificate, but the authentication fails (the client does not send
1073 * a certificate, or the client's certificate chain cannot be validated),
1074 * then the connection keeps on. Without this flag, a failed client
1075 * authentication terminates the connection.
1076 *
1077 * Notes:
1078 *
1079 * - If the client's certificate can be validated and its public key is
1080 * supported, then a wrong signature value terminates the connection
1081 * regardless of that flag.
1082 *
1083 * - If using full-static ECDH, then a failure to validate the client's
1084 * certificate prevents the handshake from succeeding.
1085 */
1086 #define BR_OPT_TOLERATE_NO_CLIENT_AUTH ((uint32_t)1 << 2)
1087
1088 /**
1089 * \brief Behavioural flag: fail on application protocol mismatch.
1090 *
1091 * The ALPN extension ([RFC 7301](https://tools.ietf.org/html/rfc7301))
1092 * allows the client to send a list of application protocol names, and
1093 * the server to select one. A mismatch is one of the following occurrences:
1094 *
1095 * - On the client: the client sends a list of names, the server
1096 * responds with a protocol name which is _not_ part of the list of
1097 * names sent by the client.
1098 *
1099 * - On the server: the client sends a list of names, and the server
1100 * is also configured with a list of names, but there is no common
1101 * protocol name between the two lists.
1102 *
1103 * Normal behaviour in case of mismatch is to report no matching name
1104 * (`br_ssl_engine_get_selected_protocol()` returns `NULL`) and carry on.
1105 * If the flag is set, then a mismatch implies a protocol failure (if
1106 * the mismatch is detected by the server, it will send a fatal alert).
1107 *
1108 * Note: even with this flag, `br_ssl_engine_get_selected_protocol()`
1109 * may still return `NULL` if the client or the server does not send an
1110 * ALPN extension at all.
1111 */
1112 #define BR_OPT_FAIL_ON_ALPN_MISMATCH ((uint32_t)1 << 3)
1113
1114 /**
1115 * \brief Set the minimum and maximum supported protocol versions.
1116 *
1117 * The two provided versions MUST be supported by the implementation
1118 * (i.e. TLS 1.0, 1.1 and 1.2), and `version_max` MUST NOT be lower
1119 * than `version_min`.
1120 *
1121 * \param cc SSL engine context.
1122 * \param version_min minimum supported TLS version.
1123 * \param version_max maximum supported TLS version.
1124 */
1125 static inline void
1126 br_ssl_engine_set_versions(br_ssl_engine_context *cc,
1127 unsigned version_min, unsigned version_max)
1128 {
1129 cc->version_min = version_min;
1130 cc->version_max = version_max;
1131 }
1132
1133 /**
1134 * \brief Set the list of cipher suites advertised by this context.
1135 *
1136 * The provided array is copied into the context. It is the caller
1137 * responsibility to ensure that all provided suites will be supported
1138 * by the context. The engine context has enough room to receive _all_
1139 * suites supported by the implementation. The provided array MUST NOT
1140 * contain duplicates.
1141 *
1142 * If the engine is for a client, the "signaling" pseudo-cipher suite
1143 * `TLS_FALLBACK_SCSV` can be added at the end of the list, if the
1144 * calling application is performing a voluntary downgrade (voluntary
1145 * downgrades are not recommended, but if such a downgrade is done, then
1146 * adding the fallback pseudo-suite is a good idea).
1147 *
1148 * \param cc SSL engine context.
1149 * \param suites cipher suites.
1150 * \param suites_num number of cipher suites.
1151 */
1152 void br_ssl_engine_set_suites(br_ssl_engine_context *cc,
1153 const uint16_t *suites, size_t suites_num);
1154
1155 /**
1156 * \brief Set the X.509 engine.
1157 *
1158 * The caller shall ensure that the X.509 engine is properly initialised.
1159 *
1160 * \param cc SSL engine context.
1161 * \param x509ctx X.509 certificate validation context.
1162 */
1163 static inline void
1164 br_ssl_engine_set_x509(br_ssl_engine_context *cc, const br_x509_class **x509ctx)
1165 {
1166 cc->x509ctx = x509ctx;
1167 }
1168
1169 /**
1170 * \brief Set the supported protocol names.
1171 *
1172 * Protocol names are part of the ALPN extension ([RFC
1173 * 7301](https://tools.ietf.org/html/rfc7301)). Each protocol name is a
1174 * character string, containing no more than 255 characters (256 with the
1175 * terminating zero). When names are set, then:
1176 *
1177 * - The client will send an ALPN extension, containing the names. If
1178 * the server responds with an ALPN extension, the client will verify
1179 * that the response contains one of its name, and report that name
1180 * through `br_ssl_engine_get_selected_protocol()`.
1181 *
1182 * - The server will parse incoming ALPN extension (from clients), and
1183 * try to find a common protocol; if none is found, the connection
1184 * is aborted with a fatal alert. On match, a response ALPN extension
1185 * is sent, and name is reported through
1186 * `br_ssl_engine_get_selected_protocol()`.
1187 *
1188 * The provided array is linked in, and must remain valid while the
1189 * connection is live.
1190 *
1191 * Names MUST NOT be empty. Names MUST NOT be longer than 255 characters
1192 * (excluding the terminating 0).
1193 *
1194 * \param ctx SSL engine context.
1195 * \param names list of protocol names (zero-terminated).
1196 * \param num number of protocol names (MUST be 1 or more).
1197 */
1198 static inline void
1199 br_ssl_engine_set_protocol_names(br_ssl_engine_context *ctx,
1200 const char **names, size_t num)
1201 {
1202 ctx->protocol_names = names;
1203 ctx->protocol_names_num = num;
1204 }
1205
1206 /**
1207 * \brief Get the selected protocol.
1208 *
1209 * If this context was initialised with a non-empty list of protocol
1210 * names, and both client and server sent ALPN extensions during the
1211 * handshake, and a common name was found, then that name is returned.
1212 * Otherwise, `NULL` is returned.
1213 *
1214 * The returned pointer is one of the pointers provided to the context
1215 * with `br_ssl_engine_set_protocol_names()`.
1216 *
1217 * \return the selected protocol, or `NULL`.
1218 */
1219 static inline const char *
1220 br_ssl_engine_get_selected_protocol(br_ssl_engine_context *ctx)
1221 {
1222 unsigned k;
1223
1224 k = ctx->selected_protocol;
1225 return (k == 0 || k == 0xFFFF) ? NULL : ctx->protocol_names[k - 1];
1226 }
1227
1228 /**
1229 * \brief Set a hash function implementation (by ID).
1230 *
1231 * Hash functions set with this call will be used for SSL/TLS specific
1232 * usages, not X.509 certificate validation. Only "standard" hash functions
1233 * may be set (MD5, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512). If `impl`
1234 * is `NULL`, then the hash function support is removed, not added.
1235 *
1236 * \param ctx SSL engine context.
1237 * \param id hash function identifier.
1238 * \param impl hash function implementation (or `NULL`).
1239 */
1240 static inline void
1241 br_ssl_engine_set_hash(br_ssl_engine_context *ctx,
1242 int id, const br_hash_class *impl)
1243 {
1244 br_multihash_setimpl(&ctx->mhash, id, impl);
1245 }
1246
1247 /**
1248 * \brief Get a hash function implementation (by ID).
1249 *
1250 * This function retrieves a hash function implementation which was
1251 * set with `br_ssl_engine_set_hash()`.
1252 *
1253 * \param ctx SSL engine context.
1254 * \param id hash function identifier.
1255 * \return the hash function implementation (or `NULL`).
1256 */
1257 static inline const br_hash_class *
1258 br_ssl_engine_get_hash(br_ssl_engine_context *ctx, int id)
1259 {
1260 return br_multihash_getimpl(&ctx->mhash, id);
1261 }
1262
1263 /**
1264 * \brief Set the PRF implementation (for TLS 1.0 and 1.1).
1265 *
1266 * This function sets (or removes, if `impl` is `NULL`) the implemenation
1267 * for the PRF used in TLS 1.0 and 1.1.
1268 *
1269 * \param cc SSL engine context.
1270 * \param impl PRF implementation (or `NULL`).
1271 */
1272 static inline void
1273 br_ssl_engine_set_prf10(br_ssl_engine_context *cc, br_tls_prf_impl impl)
1274 {
1275 cc->prf10 = impl;
1276 }
1277
1278 /**
1279 * \brief Set the PRF implementation with SHA-256 (for TLS 1.2).
1280 *
1281 * This function sets (or removes, if `impl` is `NULL`) the implemenation
1282 * for the SHA-256 variant of the PRF used in TLS 1.2.
1283 *
1284 * \param cc SSL engine context.
1285 * \param impl PRF implementation (or `NULL`).
1286 */
1287 static inline void
1288 br_ssl_engine_set_prf_sha256(br_ssl_engine_context *cc, br_tls_prf_impl impl)
1289 {
1290 cc->prf_sha256 = impl;
1291 }
1292
1293 /**
1294 * \brief Set the PRF implementation with SHA-384 (for TLS 1.2).
1295 *
1296 * This function sets (or removes, if `impl` is `NULL`) the implemenation
1297 * for the SHA-384 variant of the PRF used in TLS 1.2.
1298 *
1299 * \param cc SSL engine context.
1300 * \param impl PRF implementation (or `NULL`).
1301 */
1302 static inline void
1303 br_ssl_engine_set_prf_sha384(br_ssl_engine_context *cc, br_tls_prf_impl impl)
1304 {
1305 cc->prf_sha384 = impl;
1306 }
1307
1308 /**
1309 * \brief Set the AES/CBC implementations.
1310 *
1311 * \param cc SSL engine context.
1312 * \param impl_enc AES/CBC encryption implementation (or `NULL`).
1313 * \param impl_dec AES/CBC decryption implementation (or `NULL`).
1314 */
1315 static inline void
1316 br_ssl_engine_set_aes_cbc(br_ssl_engine_context *cc,
1317 const br_block_cbcenc_class *impl_enc,
1318 const br_block_cbcdec_class *impl_dec)
1319 {
1320 cc->iaes_cbcenc = impl_enc;
1321 cc->iaes_cbcdec = impl_dec;
1322 }
1323
1324 /**
1325 * \brief Set the AES/CTR implementation.
1326 *
1327 * \param cc SSL engine context.
1328 * \param impl AES/CTR encryption/decryption implementation (or `NULL`).
1329 */
1330 static inline void
1331 br_ssl_engine_set_aes_ctr(br_ssl_engine_context *cc,
1332 const br_block_ctr_class *impl)
1333 {
1334 cc->iaes_ctr = impl;
1335 }
1336
1337 /**
1338 * \brief Set the DES/CBC implementations.
1339 *
1340 * \param cc SSL engine context.
1341 * \param impl_enc DES/CBC encryption implementation (or `NULL`).
1342 * \param impl_dec DES/CBC decryption implementation (or `NULL`).
1343 */
1344 static inline void
1345 br_ssl_engine_set_des_cbc(br_ssl_engine_context *cc,
1346 const br_block_cbcenc_class *impl_enc,
1347 const br_block_cbcdec_class *impl_dec)
1348 {
1349 cc->ides_cbcenc = impl_enc;
1350 cc->ides_cbcdec = impl_dec;
1351 }
1352
1353 /**
1354 * \brief Set the GHASH implementation (used in GCM mode).
1355 *
1356 * \param cc SSL engine context.
1357 * \param impl GHASH implementation (or `NULL`).
1358 */
1359 static inline void
1360 br_ssl_engine_set_ghash(br_ssl_engine_context *cc, br_ghash impl)
1361 {
1362 cc->ighash = impl;
1363 }
1364
1365 /**
1366 * \brief Set the ChaCha20 implementation.
1367 *
1368 * \param cc SSL engine context.
1369 * \param ichacha ChaCha20 implementation (or `NULL`).
1370 */
1371 static inline void
1372 br_ssl_engine_set_chacha20(br_ssl_engine_context *cc,
1373 br_chacha20_run ichacha)
1374 {
1375 cc->ichacha = ichacha;
1376 }
1377
1378 /**
1379 * \brief Set the Poly1305 implementation.
1380 *
1381 * \param cc SSL engine context.
1382 * \param ipoly Poly1305 implementation (or `NULL`).
1383 */
1384 static inline void
1385 br_ssl_engine_set_poly1305(br_ssl_engine_context *cc,
1386 br_poly1305_run ipoly)
1387 {
1388 cc->ipoly = ipoly;
1389 }
1390
1391 /**
1392 * \brief Set the record encryption and decryption engines for CBC + HMAC.
1393 *
1394 * \param cc SSL engine context.
1395 * \param impl_in record CBC decryption implementation (or `NULL`).
1396 * \param impl_out record CBC encryption implementation (or `NULL`).
1397 */
1398 static inline void
1399 br_ssl_engine_set_cbc(br_ssl_engine_context *cc,
1400 const br_sslrec_in_cbc_class *impl_in,
1401 const br_sslrec_out_cbc_class *impl_out)
1402 {
1403 cc->icbc_in = impl_in;
1404 cc->icbc_out = impl_out;
1405 }
1406
1407 /**
1408 * \brief Set the record encryption and decryption engines for GCM.
1409 *
1410 * \param cc SSL engine context.
1411 * \param impl_in record GCM decryption implementation (or `NULL`).
1412 * \param impl_out record GCM encryption implementation (or `NULL`).
1413 */
1414 static inline void
1415 br_ssl_engine_set_gcm(br_ssl_engine_context *cc,
1416 const br_sslrec_in_gcm_class *impl_in,
1417 const br_sslrec_out_gcm_class *impl_out)
1418 {
1419 cc->igcm_in = impl_in;
1420 cc->igcm_out = impl_out;
1421 }
1422
1423 /**
1424 * \brief Set the record encryption and decryption engines for
1425 * ChaCha20+Poly1305.
1426 *
1427 * \param cc SSL engine context.
1428 * \param impl_in record ChaCha20 decryption implementation (or `NULL`).
1429 * \param impl_out record ChaCha20 encryption implementation (or `NULL`).
1430 */
1431 static inline void
1432 br_ssl_engine_set_chapol(br_ssl_engine_context *cc,
1433 const br_sslrec_in_chapol_class *impl_in,
1434 const br_sslrec_out_chapol_class *impl_out)
1435 {
1436 cc->ichapol_in = impl_in;
1437 cc->ichapol_out = impl_out;
1438 }
1439
1440 /**
1441 * \brief Set the EC implementation.
1442 *
1443 * The elliptic curve implementation will be used for ECDH and ECDHE
1444 * cipher suites, and for ECDSA support.
1445 *
1446 * \param cc SSL engine context.
1447 * \param iec EC implementation (or `NULL`).
1448 */
1449 static inline void
1450 br_ssl_engine_set_ec(br_ssl_engine_context *cc, const br_ec_impl *iec)
1451 {
1452 cc->iec = iec;
1453 }
1454
1455 /**
1456 * \brief Set the RSA signature verification implementation.
1457 *
1458 * On the client, this is used to verify the server's signature on its
1459 * ServerKeyExchange message (for ECDHE_RSA cipher suites). On the server,
1460 * this is used to verify the client's CertificateVerify message (if a
1461 * client certificate is requested, and that certificate contains a RSA key).
1462 *
1463 * \param cc SSL engine context.
1464 * \param irsavrfy RSA signature verification implementation.
1465 */
1466 static inline void
1467 br_ssl_engine_set_rsavrfy(br_ssl_engine_context *cc, br_rsa_pkcs1_vrfy irsavrfy)
1468 {
1469 cc->irsavrfy = irsavrfy;
1470 }
1471
1472 /*
1473 * \brief Set the ECDSA implementation (signature verification).
1474 *
1475 * On the client, this is used to verify the server's signature on its
1476 * ServerKeyExchange message (for ECDHE_ECDSA cipher suites). On the server,
1477 * this is used to verify the client's CertificateVerify message (if a
1478 * client certificate is requested, that certificate contains an EC key,
1479 * and full-static ECDH is not used).
1480 *
1481 * The ECDSA implementation will use the EC core implementation configured
1482 * in the engine context.
1483 *
1484 * \param cc client context.
1485 * \param iecdsa ECDSA verification implementation.
1486 */
1487 static inline void
1488 br_ssl_engine_set_ecdsa(br_ssl_engine_context *cc, br_ecdsa_vrfy iecdsa)
1489 {
1490 cc->iecdsa = iecdsa;
1491 }
1492
1493 /**
1494 * \brief Set the I/O buffer for the SSL engine.
1495 *
1496 * Once this call has been made, `br_ssl_client_reset()` or
1497 * `br_ssl_server_reset()` MUST be called before using the context.
1498 *
1499 * The provided buffer will be used as long as the engine context is
1500 * used. The caller is responsible for keeping it available.
1501 *
1502 * If `bidi` is 0, then the engine will operate in half-duplex mode
1503 * (it won't be able to send data while there is unprocessed incoming
1504 * data in the buffer, and it won't be able to receive data while there
1505 * is unsent data in the buffer). The optimal buffer size in half-duplex
1506 * mode is `BR_SSL_BUFSIZE_MONO`; if the buffer is larger, then extra
1507 * bytes are ignored. If the buffer is smaller, then this limits the
1508 * capacity of the engine to support all allowed record sizes.
1509 *
1510 * If `bidi` is 1, then the engine will split the buffer into two
1511 * parts, for separate handling of outgoing and incoming data. This
1512 * enables full-duplex processing, but requires more RAM. The optimal
1513 * buffer size in full-duplex mode is `BR_SSL_BUFSIZE_BIDI`; if the
1514 * buffer is larger, then extra bytes are ignored. If the buffer is
1515 * smaller, then the split will favour the incoming part, so that
1516 * interoperability is maximised.
1517 *
1518 * \param cc SSL engine context
1519 * \param iobuf I/O buffer.
1520 * \param iobuf_len I/O buffer length (in bytes).
1521 * \param bidi non-zero for full-duplex mode.
1522 */
1523 void br_ssl_engine_set_buffer(br_ssl_engine_context *cc,
1524 void *iobuf, size_t iobuf_len, int bidi);
1525
1526 /**
1527 * \brief Set the I/O buffers for the SSL engine.
1528 *
1529 * Once this call has been made, `br_ssl_client_reset()` or
1530 * `br_ssl_server_reset()` MUST be called before using the context.
1531 *
1532 * This function is similar to `br_ssl_engine_set_buffer()`, except
1533 * that it enforces full-duplex mode, and the two I/O buffers are
1534 * provided as separate chunks.
1535 *
1536 * The macros `BR_SSL_BUFSIZE_INPUT` and `BR_SSL_BUFSIZE_OUTPUT`
1537 * evaluate to the optimal (maximum) sizes for the input and output
1538 * buffer, respectively.
1539 *
1540 * \param cc SSL engine context
1541 * \param ibuf input buffer.
1542 * \param ibuf_len input buffer length (in bytes).
1543 * \param obuf output buffer.
1544 * \param obuf_len output buffer length (in bytes).
1545 */
1546 void br_ssl_engine_set_buffers_bidi(br_ssl_engine_context *cc,
1547 void *ibuf, size_t ibuf_len, void *obuf, size_t obuf_len);
1548
1549 /**
1550 * \brief Inject some "initial entropy" in the context.
1551 *
1552 * This entropy will be added to what can be obtained from the
1553 * underlying operating system, if that OS is supported.
1554 *
1555 * This function may be called several times; all injected entropy chunks
1556 * are cumulatively mixed.
1557 *
1558 * If entropy gathering from the OS is supported and compiled in, then this
1559 * step is optional. Otherwise, it is mandatory to inject randomness, and
1560 * the caller MUST take care to push (as one or several successive calls)
1561 * enough entropy to achieve cryptographic resistance (at least 80 bits,
1562 * preferably 128 or more). The engine will report an error if no entropy
1563 * was provided and none can be obtained from the OS.
1564 *
1565 * Take care that this function cannot assess the cryptographic quality of
1566 * the provided bytes.
1567 *
1568 * In all generality, "entropy" must here be considered to mean "that
1569 * which the attacker cannot predict". If your OS/architecture does not
1570 * have a suitable source of randomness, then you can make do with the
1571 * combination of a large enough secret value (possibly a copy of an
1572 * asymmetric private key that you also store on the system) AND a
1573 * non-repeating value (e.g. current time, provided that the local clock
1574 * cannot be reset or altered by the attacker).
1575 *
1576 * \param cc SSL engine context.
1577 * \param data extra entropy to inject.
1578 * \param len length of the extra data (in bytes).
1579 */
1580 void br_ssl_engine_inject_entropy(br_ssl_engine_context *cc,
1581 const void *data, size_t len);
1582
1583 /**
1584 * \brief Get the "server name" in this engine.
1585 *
1586 * For clients, this is the name provided with `br_ssl_client_reset()`;
1587 * for servers, this is the name received from the client as part of the
1588 * ClientHello message. If there is no such name (e.g. the client did
1589 * not send an SNI extension) then the returned string is empty
1590 * (returned pointer points to a byte of value 0).
1591 *
1592 * The returned pointer refers to a buffer inside the context, which may
1593 * be overwritten as part of normal SSL activity (even within the same
1594 * connection, if a renegotiation occurs).
1595 *
1596 * \param cc SSL engine context.
1597 * \return the server name (possibly empty).
1598 */
1599 static inline const char *
1600 br_ssl_engine_get_server_name(const br_ssl_engine_context *cc)
1601 {
1602 return cc->server_name;
1603 }
1604
1605 /**
1606 * \brief Get the protocol version.
1607 *
1608 * This function returns the protocol version that is used by the
1609 * engine. That value is set after sending (for a server) or receiving
1610 * (for a client) the ServerHello message.
1611 *
1612 * \param cc SSL engine context.
1613 * \return the protocol version.
1614 */
1615 static inline unsigned
1616 br_ssl_engine_get_version(const br_ssl_engine_context *cc)
1617 {
1618 return cc->session.version;
1619 }
1620
1621 /**
1622 * \brief Get a copy of the session parameters.
1623 *
1624 * The session parameters are filled during the handshake, so this
1625 * function shall not be called before completion of the handshake.
1626 * The initial handshake is completed when the context first allows
1627 * application data to be injected.
1628 *
1629 * This function copies the current session parameters into the provided
1630 * structure. Beware that the session parameters include the master
1631 * secret, which is sensitive data, to handle with great care.
1632 *
1633 * \param cc SSL engine context.
1634 * \param pp destination structure for the session parameters.
1635 */
1636 static inline void
1637 br_ssl_engine_get_session_parameters(const br_ssl_engine_context *cc,
1638 br_ssl_session_parameters *pp)
1639 {
1640 memcpy(pp, &cc->session, sizeof *pp);
1641 }
1642
1643 /**
1644 * \brief Set the session parameters to the provided values.
1645 *
1646 * This function is meant to be used in the client, before doing a new
1647 * handshake; a session resumption will be attempted with these
1648 * parameters. In the server, this function has no effect.
1649 *
1650 * \param cc SSL engine context.
1651 * \param pp source structure for the session parameters.
1652 */
1653 static inline void
1654 br_ssl_engine_set_session_parameters(br_ssl_engine_context *cc,
1655 const br_ssl_session_parameters *pp)
1656 {
1657 memcpy(&cc->session, pp, sizeof *pp);
1658 }
1659
1660 /**
1661 * \brief Get identifier for the curve used for key exchange.
1662 *
1663 * If the cipher suite uses ECDHE, then this function returns the
1664 * identifier for the curve used for transient parameters. This is
1665 * defined during the course of the handshake, when the ServerKeyExchange
1666 * is sent (on the server) or received (on the client). If the
1667 * cipher suite does not use ECDHE (e.g. static ECDH, or RSA key
1668 * exchange), then this value is indeterminate.
1669 *
1670 * @param cc SSL engine context.
1671 * @return the ECDHE curve identifier.
1672 */
1673 static inline int
1674 br_ssl_engine_get_ecdhe_curve(br_ssl_engine_context *cc)
1675 {
1676 return cc->ecdhe_curve;
1677 }
1678
1679 /**
1680 * \brief Get the current engine state.
1681 *
1682 * An SSL engine (client or server) has, at any time, a state which is
1683 * the combination of zero, one or more of these flags:
1684 *
1685 * - `BR_SSL_CLOSED`
1686 *
1687 * Engine is finished, no more I/O (until next reset).
1688 *
1689 * - `BR_SSL_SENDREC`
1690 *
1691 * Engine has some bytes to send to the peer.
1692 *
1693 * - `BR_SSL_RECVREC`
1694 *
1695 * Engine expects some bytes from the peer.
1696 *
1697 * - `BR_SSL_SENDAPP`
1698 *
1699 * Engine may receive application data to send (or flush).
1700 *
1701 * - `BR_SSL_RECVAPP`
1702 *
1703 * Engine has obtained some application data from the peer,
1704 * that should be read by the caller.
1705 *
1706 * If no flag at all is set (state value is 0), then the engine is not
1707 * fully initialised yet.
1708 *
1709 * The `BR_SSL_CLOSED` flag is exclusive; when it is set, no other flag
1710 * is set. To distinguish between a normal closure and an error, use
1711 * `br_ssl_engine_last_error()`.
1712 *
1713 * Generally speaking, `BR_SSL_SENDREC` and `BR_SSL_SENDAPP` are mutually
1714 * exclusive: the input buffer, at any point, either accumulates
1715 * plaintext data, or contains an assembled record that is being sent.
1716 * Similarly, `BR_SSL_RECVREC` and `BR_SSL_RECVAPP` are mutually exclusive.
1717 * This may change in a future library version.
1718 *
1719 * \param cc SSL engine context.
1720 * \return the current engine state.
1721 */
1722 unsigned br_ssl_engine_current_state(const br_ssl_engine_context *cc);
1723
1724 /** \brief SSL engine state: closed or failed. */
1725 #define BR_SSL_CLOSED 0x0001
1726 /** \brief SSL engine state: record data is ready to be sent to the peer. */
1727 #define BR_SSL_SENDREC 0x0002
1728 /** \brief SSL engine state: engine may receive records from the peer. */
1729 #define BR_SSL_RECVREC 0x0004
1730 /** \brief SSL engine state: engine may accept application data to send. */
1731 #define BR_SSL_SENDAPP 0x0008
1732 /** \brief SSL engine state: engine has received application data. */
1733 #define BR_SSL_RECVAPP 0x0010
1734
1735 /**
1736 * \brief Get the engine error indicator.
1737 *
1738 * The error indicator is `BR_ERR_OK` (0) if no error was encountered
1739 * since the last call to `br_ssl_client_reset()` or
1740 * `br_ssl_server_reset()`. Other status values are "sticky": they
1741 * remain set, and prevent all I/O activity, until cleared. Only the
1742 * reset calls clear the error indicator.
1743 *
1744 * \param cc SSL engine context.
1745 * \return 0, or a non-zero error code.
1746 */
1747 static inline int
1748 br_ssl_engine_last_error(const br_ssl_engine_context *cc)
1749 {
1750 return cc->err;
1751 }
1752
1753 /*
1754 * There are four I/O operations, each identified by a symbolic name:
1755 *
1756 * sendapp inject application data in the engine
1757 * recvapp retrieving application data from the engine
1758 * sendrec sending records on the transport medium
1759 * recvrec receiving records from the transport medium
1760 *
1761 * Terminology works thus: in a layered model where the SSL engine sits
1762 * between the application and the network, "send" designates operations
1763 * where bytes flow from application to network, and "recv" for the
1764 * reverse operation. Application data (the plaintext that is to be
1765 * conveyed through SSL) is "app", while encrypted records are "rec".
1766 * Note that from the SSL engine point of view, "sendapp" and "recvrec"
1767 * designate bytes that enter the engine ("inject" operation), while
1768 * "recvapp" and "sendrec" designate bytes that exit the engine
1769 * ("extract" operation).
1770 *
1771 * For the operation 'xxx', two functions are defined:
1772 *
1773 * br_ssl_engine_xxx_buf
1774 * Returns a pointer and length to the buffer to use for that
1775 * operation. '*len' is set to the number of bytes that may be read
1776 * from the buffer (extract operation) or written to the buffer
1777 * (inject operation). If no byte may be exchanged for that operation
1778 * at that point, then '*len' is set to zero, and NULL is returned.
1779 * The engine state is unmodified by this call.
1780 *
1781 * br_ssl_engine_xxx_ack
1782 * Informs the engine that 'len' bytes have been read from the buffer
1783 * (extract operation) or written to the buffer (inject operation).
1784 * The 'len' value MUST NOT be zero. The 'len' value MUST NOT exceed
1785 * that which was obtained from a preceeding br_ssl_engine_xxx_buf()
1786 * call.
1787 */
1788
1789 /**
1790 * \brief Get buffer for application data to send.
1791 *
1792 * If the engine is ready to accept application data to send to the
1793 * peer, then this call returns a pointer to the buffer where such
1794 * data shall be written, and its length is written in `*len`.
1795 * Otherwise, `*len` is set to 0 and `NULL` is returned.
1796 *
1797 * \param cc SSL engine context.
1798 * \param len receives the application data output buffer length, or 0.
1799 * \return the application data output buffer, or `NULL`.
1800 */
1801 unsigned char *br_ssl_engine_sendapp_buf(
1802 const br_ssl_engine_context *cc, size_t *len);
1803
1804 /**
1805 * \brief Inform the engine of some new application data.
1806 *
1807 * After writing `len` bytes in the buffer returned by
1808 * `br_ssl_engine_sendapp_buf()`, the application shall call this
1809 * function to trigger any relevant processing. The `len` parameter
1810 * MUST NOT be 0, and MUST NOT exceed the value obtained in the
1811 * `br_ssl_engine_sendapp_buf()` call.
1812 *
1813 * \param cc SSL engine context.
1814 * \param len number of bytes pushed (not zero).
1815 */
1816 void br_ssl_engine_sendapp_ack(br_ssl_engine_context *cc, size_t len);
1817
1818 /**
1819 * \brief Get buffer for received application data.
1820 *
1821 * If the engine has received application data from the peer, hen this
1822 * call returns a pointer to the buffer from where such data shall be
1823 * read, and its length is written in `*len`. Otherwise, `*len` is set
1824 * to 0 and `NULL` is returned.
1825 *
1826 * \param cc SSL engine context.
1827 * \param len receives the application data input buffer length, or 0.
1828 * \return the application data input buffer, or `NULL`.
1829 */
1830 unsigned char *br_ssl_engine_recvapp_buf(
1831 const br_ssl_engine_context *cc, size_t *len);
1832
1833 /**
1834 * \brief Acknowledge some received application data.
1835 *
1836 * After reading `len` bytes from the buffer returned by
1837 * `br_ssl_engine_recvapp_buf()`, the application shall call this
1838 * function to trigger any relevant processing. The `len` parameter
1839 * MUST NOT be 0, and MUST NOT exceed the value obtained in the
1840 * `br_ssl_engine_recvapp_buf()` call.
1841 *
1842 * \param cc SSL engine context.
1843 * \param len number of bytes read (not zero).
1844 */
1845 void br_ssl_engine_recvapp_ack(br_ssl_engine_context *cc, size_t len);
1846
1847 /**
1848 * \brief Get buffer for record data to send.
1849 *
1850 * If the engine has prepared some records to send to the peer, then this
1851 * call returns a pointer to the buffer from where such data shall be
1852 * read, and its length is written in `*len`. Otherwise, `*len` is set
1853 * to 0 and `NULL` is returned.
1854 *
1855 * \param cc SSL engine context.
1856 * \param len receives the record data output buffer length, or 0.
1857 * \return the record data output buffer, or `NULL`.
1858 */
1859 unsigned char *br_ssl_engine_sendrec_buf(
1860 const br_ssl_engine_context *cc, size_t *len);
1861
1862 /**
1863 * \brief Acknowledge some sent record data.
1864 *
1865 * After reading `len` bytes from the buffer returned by
1866 * `br_ssl_engine_sendrec_buf()`, the application shall call this
1867 * function to trigger any relevant processing. The `len` parameter
1868 * MUST NOT be 0, and MUST NOT exceed the value obtained in the
1869 * `br_ssl_engine_sendrec_buf()` call.
1870 *
1871 * \param cc SSL engine context.
1872 * \param len number of bytes read (not zero).
1873 */
1874 void br_ssl_engine_sendrec_ack(br_ssl_engine_context *cc, size_t len);
1875
1876 /**
1877 * \brief Get buffer for incoming records.
1878 *
1879 * If the engine is ready to accept records from the peer, then this
1880 * call returns a pointer to the buffer where such data shall be
1881 * written, and its length is written in `*len`. Otherwise, `*len` is
1882 * set to 0 and `NULL` is returned.
1883 *
1884 * \param cc SSL engine context.
1885 * \param len receives the record data input buffer length, or 0.
1886 * \return the record data input buffer, or `NULL`.
1887 */
1888 unsigned char *br_ssl_engine_recvrec_buf(
1889 const br_ssl_engine_context *cc, size_t *len);
1890
1891 /**
1892 * \brief Inform the engine of some new record data.
1893 *
1894 * After writing `len` bytes in the buffer returned by
1895 * `br_ssl_engine_recvrec_buf()`, the application shall call this
1896 * function to trigger any relevant processing. The `len` parameter
1897 * MUST NOT be 0, and MUST NOT exceed the value obtained in the
1898 * `br_ssl_engine_recvrec_buf()` call.
1899 *
1900 * \param cc SSL engine context.
1901 * \param len number of bytes pushed (not zero).
1902 */
1903 void br_ssl_engine_recvrec_ack(br_ssl_engine_context *cc, size_t len);
1904
1905 /**
1906 * \brief Flush buffered application data.
1907 *
1908 * If some application data has been buffered in the engine, then wrap
1909 * it into a record and mark it for sending. If no application data has
1910 * been buffered but the engine would be ready to accept some, AND the
1911 * `force` parameter is non-zero, then an empty record is assembled and
1912 * marked for sending. In all other cases, this function does nothing.
1913 *
1914 * Empty records are technically legal, but not all existing SSL/TLS
1915 * implementations support them. Empty records can be useful as a
1916 * transparent "keep-alive" mechanism to maintain some low-level
1917 * network activity.
1918 *
1919 * \param cc SSL engine context.
1920 * \param force non-zero to force sending an empty record.
1921 */
1922 void br_ssl_engine_flush(br_ssl_engine_context *cc, int force);
1923
1924 /**
1925 * \brief Initiate a closure.
1926 *
1927 * If, at that point, the context is open and in ready state, then a
1928 * `close_notify` alert is assembled and marked for sending; this
1929 * triggers the closure protocol. Otherwise, no such alert is assembled.
1930 *
1931 * \param cc SSL engine context.
1932 */
1933 void br_ssl_engine_close(br_ssl_engine_context *cc);
1934
1935 /**
1936 * \brief Initiate a renegotiation.
1937 *
1938 * If the engine is failed or closed, or if the peer is known not to
1939 * support secure renegotiation (RFC 5746), or if renegotiations have
1940 * been disabled with the `BR_OPT_NO_RENEGOTIATION` flag, then this
1941 * function returns 0 and nothing else happens.
1942 *
1943 * Otherwise, this function returns 1, and a renegotiation attempt is
1944 * triggered (if a handshake is already ongoing at that point, then
1945 * no new handshake is triggered).
1946 *
1947 * \param cc SSL engine context.
1948 * \return 1 on success, 0 on error.
1949 */
1950 int br_ssl_engine_renegotiate(br_ssl_engine_context *cc);
1951
1952 /*
1953 * Pre-declaration for the SSL client context.
1954 */
1955 typedef struct br_ssl_client_context_ br_ssl_client_context;
1956
1957 /**
1958 * \brief Type for the client certificate, if requested by the server.
1959 */
1960 typedef struct {
1961 /**
1962 * \brief Authentication type.
1963 *
1964 * This is either `BR_AUTH_RSA` (RSA signature), `BR_AUTH_ECDSA`
1965 * (ECDSA signature), or `BR_AUTH_ECDH` (static ECDH key exchange).
1966 */
1967 int auth_type;
1968
1969 /**
1970 * \brief Hash function for computing the CertificateVerify.
1971 *
1972 * This is the symbolic identifier for the hash function that
1973 * will be used to produce the hash of handshake messages, to
1974 * be signed into the CertificateVerify. For full static ECDH
1975 * (client and server certificates are both EC in the same
1976 * curve, and static ECDH is used), this value is set to -1.
1977 *
1978 * Take care that with TLS 1.0 and 1.1, that value MUST match
1979 * the protocol requirements: value must be 0 (MD5+SHA-1) for
1980 * a RSA signature, or 2 (SHA-1) for an ECDSA signature. Only
1981 * TLS 1.2 allows for other hash functions.
1982 */
1983 int hash_id;
1984
1985 /**
1986 * \brief Certificate chain to send to the server.
1987 *
1988 * This is an array of `br_x509_certificate` objects, each
1989 * normally containing a DER-encoded certificate. The client
1990 * code does not try to decode these elements. If there is no
1991 * chain to send to the server, then this pointer shall be
1992 * set to `NULL`.
1993 */
1994 const br_x509_certificate *chain;
1995
1996 /**
1997 * \brief Certificate chain length (number of certificates).
1998 *
1999 * If there is no chain to send to the server, then this value
2000 * shall be set to 0.
2001 */
2002 size_t chain_len;
2003
2004 } br_ssl_client_certificate;
2005
2006 /*
2007 * Note: the constants below for signatures match the TLS constants.
2008 */
2009
2010 /** \brief Client authentication type: static ECDH. */
2011 #define BR_AUTH_ECDH 0
2012 /** \brief Client authentication type: RSA signature. */
2013 #define BR_AUTH_RSA 1
2014 /** \brief Client authentication type: ECDSA signature. */
2015 #define BR_AUTH_ECDSA 3
2016
2017 /**
2018 * \brief Class type for a certificate handler (client side).
2019 *
2020 * A certificate handler selects a client certificate chain to send to
2021 * the server, upon explicit request from that server. It receives
2022 * the list of trust anchor DN from the server, and supported types
2023 * of certificates and signatures, and returns the chain to use. It
2024 * is also invoked to perform the corresponding private key operation
2025 * (a signature, or an ECDH computation).
2026 *
2027 * The SSL client engine will first push the trust anchor DN with
2028 * `start_name_list()`, `start_name()`, `append_name()`, `end_name()`
2029 * and `end_name_list()`. Then it will call `choose()`, to select the
2030 * actual chain (and signature/hash algorithms). Finally, it will call
2031 * either `do_sign()` or `do_keyx()`, depending on the algorithm choices.
2032 */
2033 typedef struct br_ssl_client_certificate_class_ br_ssl_client_certificate_class;
2034 struct br_ssl_client_certificate_class_ {
2035 /**
2036 * \brief Context size (in bytes).
2037 */
2038 size_t context_size;
2039
2040 /**
2041 * \brief Begin reception of a list of trust anchor names. This
2042 * is called while parsing the incoming CertificateRequest.
2043 *
2044 * \param pctx certificate handler context.
2045 */
2046 void (*start_name_list)(const br_ssl_client_certificate_class **pctx);
2047
2048 /**
2049 * \brief Begin reception of a new trust anchor name.
2050 *
2051 * The total encoded name length is provided; it is less than
2052 * 65535 bytes.
2053 *
2054 * \param pctx certificate handler context.
2055 * \param len encoded name length (in bytes).
2056 */
2057 void (*start_name)(const br_ssl_client_certificate_class **pctx,
2058 size_t len);
2059
2060 /**
2061 * \brief Receive some more bytes for the current trust anchor name.
2062 *
2063 * The provided reference (`data`) points to a transient buffer
2064 * they may be reused as soon as this function returns. The chunk
2065 * length (`len`) is never zero.
2066 *
2067 * \param pctx certificate handler context.
2068 * \param data anchor name chunk.
2069 * \param len anchor name chunk length (in bytes).
2070 */
2071 void (*append_name)(const br_ssl_client_certificate_class **pctx,
2072 const unsigned char *data, size_t len);
2073
2074 /**
2075 * \brief End current trust anchor name.
2076 *
2077 * This function is called when all the encoded anchor name data
2078 * has been provided.
2079 *
2080 * \param pctx certificate handler context.
2081 */
2082 void (*end_name)(const br_ssl_client_certificate_class **pctx);
2083
2084 /**
2085 * \brief End list of trust anchor names.
2086 *
2087 * This function is called when all the anchor names in the
2088 * CertificateRequest message have been obtained.
2089 *
2090 * \param pctx certificate handler context.
2091 */
2092 void (*end_name_list)(const br_ssl_client_certificate_class **pctx);
2093
2094 /**
2095 * \brief Select client certificate and algorithms.
2096 *
2097 * This callback function shall fill the provided `choices`
2098 * structure with the selected algorithms and certificate chain.
2099 * The `hash_id`, `chain` and `chain_len` fields must be set. If
2100 * the client cannot or does not wish to send a certificate,
2101 * then it shall set `chain` to `NULL` and `chain_len` to 0.
2102 *
2103 * The `auth_types` parameter describes the authentication types,
2104 * signature algorithms and hash functions that are supported by
2105 * both the client context and the server, and compatible with
2106 * the current protocol version. This is a bit field with the
2107 * following contents:
2108 *
2109 * - If RSA signatures with hash function x are supported, then
2110 * bit x is set.
2111 *
2112 * - If ECDSA signatures with hash function x are supported,
2113 * then bit 8+x is set.
2114 *
2115 * - If static ECDH is supported, with a RSA-signed certificate,
2116 * then bit 16 is set.
2117 *
2118 * - If static ECDH is supported, with an ECDSA-signed certificate,
2119 * then bit 17 is set.
2120 *
2121 * Notes:
2122 *
2123 * - When using TLS 1.0 or 1.1, the hash function for RSA
2124 * signatures is always the special MD5+SHA-1 (id 0), and the
2125 * hash function for ECDSA signatures is always SHA-1 (id 2).
2126 *
2127 * - When using TLS 1.2, the list of hash functions is trimmed
2128 * down to include only hash functions that the client context
2129 * can support. The actual server list can be obtained with
2130 * `br_ssl_client_get_server_hashes()`; that list may be used
2131 * to select the certificate chain to send to the server.
2132 *
2133 * \param pctx certificate handler context.
2134 * \param cc SSL client context.
2135 * \param auth_types supported authentication types and algorithms.
2136 * \param choices destination structure for the policy choices.
2137 */
2138 void (*choose)(const br_ssl_client_certificate_class **pctx,
2139 const br_ssl_client_context *cc, uint32_t auth_types,
2140 br_ssl_client_certificate *choices);
2141
2142 /**
2143 * \brief Perform key exchange (client part).
2144 *
2145 * This callback is invoked in case of a full static ECDH key
2146 * exchange:
2147 *
2148 * - the cipher suite uses `ECDH_RSA` or `ECDH_ECDSA`;
2149 *
2150 * - the server requests a client certificate;
2151 *
2152 * - the client has, and sends, a client certificate that
2153 * uses an EC key in the same curve as the server's key,
2154 * and chooses static ECDH (the `hash_id` field in the choice
2155 * structure was set to -1).
2156 *
2157 * In that situation, this callback is invoked to compute the
2158 * client-side ECDH: the provided `data` (of length `*len` bytes)
2159 * is the server's public key point (as decoded from its
2160 * certificate), and the client shall multiply that point with
2161 * its own private key, and write back the X coordinate of the
2162 * resulting point in the same buffer, starting at offset 0.
2163 * The `*len` value shall be modified to designate the actual
2164 * length of the X coordinate.
2165 *
2166 * The callback must uphold the following:
2167 *
2168 * - If the input array does not have the proper length for
2169 * an encoded curve point, then an error (0) shall be reported.
2170 *
2171 * - If the input array has the proper length, then processing
2172 * MUST be constant-time, even if the data is not a valid
2173 * encoded point.
2174 *
2175 * - This callback MUST check that the input point is valid.
2176 *
2177 * Returned value is 1 on success, 0 on error.
2178 *
2179 * \param pctx certificate handler context.
2180 * \param data server public key point.
2181 * \param len public key point length / X coordinate length.
2182 * \return 1 on success, 0 on error.
2183 */
2184 uint32_t (*do_keyx)(const br_ssl_client_certificate_class **pctx,
2185 unsigned char *data, size_t *len);
2186
2187 /**
2188 * \brief Perform a signature (client authentication).
2189 *
2190 * This callback is invoked when a client certificate was sent,
2191 * and static ECDH is not used. It shall compute a signature,
2192 * using the client's private key, over the provided hash value
2193 * (which is the hash of all previous handshake messages).
2194 *
2195 * On input, the hash value to sign is in `data`, of size
2196 * `hv_len`; the involved hash function is identified by
2197 * `hash_id`. The signature shall be computed and written
2198 * back into `data`; the total size of that buffer is `len`
2199 * bytes.
2200 *
2201 * This callback shall verify that the signature length does not
2202 * exceed `len` bytes, and abstain from writing the signature if
2203 * it does not fit.
2204 *
2205 * For RSA signatures, the `hash_id` may be 0, in which case
2206 * this is the special header-less signature specified in TLS 1.0
2207 * and 1.1, with a 36-byte hash value. Otherwise, normal PKCS#1
2208 * v1.5 signatures shall be computed.
2209 *
2210 * For ECDSA signatures, the signature value shall use the ASN.1
2211 * based encoding.
2212 *
2213 * Returned value is the signature length (in bytes), or 0 on error.
2214 *
2215 * \param pctx certificate handler context.
2216 * \param hash_id hash function identifier.
2217 * \param hv_len hash value length (in bytes).
2218 * \param data input/output buffer (hash value, then signature).
2219 * \param len total buffer length (in bytes).
2220 * \return signature length (in bytes) on success, or 0 on error.
2221 */
2222 size_t (*do_sign)(const br_ssl_client_certificate_class **pctx,
2223 int hash_id, size_t hv_len, unsigned char *data, size_t len);
2224 };
2225
2226 /**
2227 * \brief A single-chain RSA client certificate handler.
2228 *
2229 * This handler uses a single certificate chain, with a RSA
2230 * signature. The list of trust anchor DN is ignored.
2231 *
2232 * Apart from the first field (vtable pointer), its contents are
2233 * opaque and shall not be accessed directly.
2234 */
2235 typedef struct {
2236 /** \brief Pointer to vtable. */
2237 const br_ssl_client_certificate_class *vtable;
2238 #ifndef BR_DOXYGEN_IGNORE
2239 const br_x509_certificate *chain;
2240 size_t chain_len;
2241 const br_rsa_private_key *sk;
2242 br_rsa_pkcs1_sign irsasign;
2243 #endif
2244 } br_ssl_client_certificate_rsa_context;
2245
2246 /**
2247 * \brief A single-chain EC client certificate handler.
2248 *
2249 * This handler uses a single certificate chain, with a RSA
2250 * signature. The list of trust anchor DN is ignored.
2251 *
2252 * This handler may support both static ECDH, and ECDSA signatures
2253 * (either usage may be selectively disabled).
2254 *
2255 * Apart from the first field (vtable pointer), its contents are
2256 * opaque and shall not be accessed directly.
2257 */
2258 typedef struct {
2259 /** \brief Pointer to vtable. */
2260 const br_ssl_client_certificate_class *vtable;
2261 #ifndef BR_DOXYGEN_IGNORE
2262 const br_x509_certificate *chain;
2263 size_t chain_len;
2264 const br_ec_private_key *sk;
2265 unsigned allowed_usages;
2266 unsigned issuer_key_type;
2267 const br_multihash_context *mhash;
2268 const br_ec_impl *iec;
2269 br_ecdsa_sign iecdsa;
2270 #endif
2271 } br_ssl_client_certificate_ec_context;
2272
2273 /**
2274 * \brief Context structure for a SSL client.
2275 *
2276 * The first field (called `eng`) is the SSL engine; all functions that
2277 * work on a `br_ssl_engine_context` structure shall take as parameter
2278 * a pointer to that field. The other structure fields are opaque and
2279 * must not be accessed directly.
2280 */
2281 struct br_ssl_client_context_ {
2282 /**
2283 * \brief The encapsulated engine context.
2284 */
2285 br_ssl_engine_context eng;
2286
2287 #ifndef BR_DOXYGEN_IGNORE
2288 /*
2289 * Minimum ClientHello length; padding with an extension (RFC
2290 * 7685) is added if necessary to match at least that length.
2291 * Such padding is nominally unnecessary, but it has been used
2292 * to work around some server implementation bugs.
2293 */
2294 uint16_t min_clienthello_len;
2295
2296 /*
2297 * Bit field for algoithms (hash + signature) supported by the
2298 * server when requesting a client certificate.
2299 */
2300 uint32_t hashes;
2301
2302 /*
2303 * Server's public key curve.
2304 */
2305 int server_curve;
2306
2307 /*
2308 * Context for certificate handler.
2309 */
2310 const br_ssl_client_certificate_class **client_auth_vtable;
2311
2312 /*
2313 * Client authentication type.
2314 */
2315 unsigned char auth_type;
2316
2317 /*
2318 * Hash function to use for the client signature. This is 0xFF
2319 * if static ECDH is used.
2320 */
2321 unsigned char hash_id;
2322
2323 /*
2324 * For the core certificate handlers, thus avoiding (in most
2325 * cases) the need for an externally provided policy context.
2326 */
2327 union {
2328 const br_ssl_client_certificate_class *vtable;
2329 br_ssl_client_certificate_rsa_context single_rsa;
2330 br_ssl_client_certificate_ec_context single_ec;
2331 } client_auth;
2332
2333 /*
2334 * Implementations.
2335 */
2336 br_rsa_public irsapub;
2337 #endif
2338 };
2339
2340 /**
2341 * \brief Get the hash functions and signature algorithms supported by
2342 * the server.
2343 *
2344 * This value is a bit field:
2345 *
2346 * - If RSA (PKCS#1 v1.5) is supported with hash function of ID `x`,
2347 * then bit `x` is set (hash function ID is 0 for the special MD5+SHA-1,
2348 * or 2 to 6 for the SHA family).
2349 *
2350 * - If ECDSA is suported with hash function of ID `x`, then bit `8+x`
2351 * is set.
2352 *
2353 * - Newer algorithms are symbolic 16-bit identifiers that do not
2354 * represent signature algorithm and hash function separately. If
2355 * the TLS-level identifier is `0x0800+x` for a `x` in the 0..15
2356 * range, then bit `16+x` is set.
2357 *
2358 * "New algorithms" are currently defined only in draft documents, so
2359 * this support is subject to possible change. Right now (early 2017),
2360 * this maps ed25519 (EdDSA on Curve25519) to bit 23, and ed448 (EdDSA
2361 * on Curve448) to bit 24. If the identifiers on the wire change in
2362 * future document, then the decoding mechanism in BearSSL will be
2363 * amended to keep mapping ed25519 and ed448 on bits 23 and 24,
2364 * respectively. Mapping of other new algorithms (e.g. RSA/PSS) is not
2365 * guaranteed yet.
2366 *
2367 * \param cc client context.
2368 * \return the server-supported hash functions and signature algorithms.
2369 */
2370 static inline uint32_t
2371 br_ssl_client_get_server_hashes(const br_ssl_client_context *cc)
2372 {
2373 return cc->hashes;
2374 }
2375
2376 /**
2377 * \brief Get the server key curve.
2378 *
2379 * This function returns the ID for the curve used by the server's public
2380 * key. This is set when the server's certificate chain is processed;
2381 * this value is 0 if the server's key is not an EC key.
2382 *
2383 * \return the server's public key curve ID, or 0.
2384 */
2385 static inline int
2386 br_ssl_client_get_server_curve(const br_ssl_client_context *cc)
2387 {
2388 return cc->server_curve;
2389 }
2390
2391 /*
2392 * Each br_ssl_client_init_xxx() function sets the list of supported
2393 * cipher suites and used implementations, as specified by the profile
2394 * name 'xxx'. Defined profile names are:
2395 *
2396 * full all supported versions and suites; constant-time implementations
2397 * TODO: add other profiles
2398 */
2399
2400 /**
2401 * \brief SSL client profile: full.
2402 *
2403 * This function initialises the provided SSL client context with
2404 * all supported algorithms and cipher suites. It also initialises
2405 * a companion X.509 validation engine with all supported algorithms,
2406 * and the provided trust anchors; the X.509 engine will be used by
2407 * the client context to validate the server's certificate.
2408 *
2409 * \param cc client context to initialise.
2410 * \param xc X.509 validation context to initialise.
2411 * \param trust_anchors trust anchors to use.
2412 * \param trust_anchors_num number of trust anchors.
2413 */
2414 void br_ssl_client_init_full(br_ssl_client_context *cc,
2415 br_x509_minimal_context *xc,
2416 const br_x509_trust_anchor *trust_anchors, size_t trust_anchors_num);
2417
2418 /**
2419 * \brief Clear the complete contents of a SSL client context.
2420 *
2421 * Everything is cleared, including the reference to the configured buffer,
2422 * implementations, cipher suites and state. This is a preparatory step
2423 * to assembling a custom profile.
2424 *
2425 * \param cc client context to clear.
2426 */
2427 void br_ssl_client_zero(br_ssl_client_context *cc);
2428
2429 /**
2430 * \brief Set an externally provided client certificate handler context.
2431 *
2432 * The handler's methods are invoked when the server requests a client
2433 * certificate.
2434 *
2435 * \param cc client context.
2436 * \param pctx certificate handler context (pointer to its vtable field).
2437 */
2438 static inline void
2439 br_ssl_client_set_client_certificate(br_ssl_client_context *cc,
2440 const br_ssl_client_certificate_class **pctx)
2441 {
2442 cc->client_auth_vtable = pctx;
2443 }
2444
2445 /**
2446 * \brief Set the RSA public-key operations implementation.
2447 *
2448 * This will be used to encrypt the pre-master secret with the server's
2449 * RSA public key (RSA-encryption cipher suites only).
2450 *
2451 * \param cc client context.
2452 * \param irsapub RSA public-key encryption implementation.
2453 */
2454 static inline void
2455 br_ssl_client_set_rsapub(br_ssl_client_context *cc, br_rsa_public irsapub)
2456 {
2457 cc->irsapub = irsapub;
2458 }
2459
2460 /**
2461 * \brief Set the minimum ClientHello length (RFC 7685 padding).
2462 *
2463 * If this value is set and the ClientHello would be shorter, then
2464 * the Pad ClientHello extension will be added with enough padding bytes
2465 * to reach the target size. Because of the extension header, the resulting
2466 * size will sometimes be slightly more than `len` bytes if the target
2467 * size cannot be exactly met.
2468 *
2469 * The target length relates to the _contents_ of the ClientHello, not
2470 * counting its 4-byte header. For instance, if `len` is set to 512,
2471 * then the padding will bring the ClientHello size to 516 bytes with its
2472 * header, and 521 bytes when counting the 5-byte record header.
2473 *
2474 * \param cc client context.
2475 * \param len minimum ClientHello length (in bytes).
2476 */
2477 static inline void
2478 br_ssl_client_set_min_clienthello_len(br_ssl_client_context *cc, uint16_t len)
2479 {
2480 cc->min_clienthello_len = len;
2481 }
2482
2483 /**
2484 * \brief Prepare or reset a client context for a new connection.
2485 *
2486 * The `server_name` parameter is used to fill the SNI extension; the
2487 * X.509 "minimal" engine will also match that name against the server
2488 * names included in the server's certificate. If the parameter is
2489 * `NULL` then no SNI extension will be sent, and the X.509 "minimal"
2490 * engine (if used for server certificate validation) will not check
2491 * presence of any specific name in the received certificate.
2492 *
2493 * Therefore, setting the `server_name` to `NULL` shall be reserved
2494 * to cases where alternate or additional methods are used to ascertain
2495 * that the right server public key is used (e.g. a "known key" model).
2496 *
2497 * If `resume_session` is non-zero and the context was previously used
2498 * then the session parameters may be reused (depending on whether the
2499 * server previously sent a non-empty session ID, and accepts the session
2500 * resumption). The session parameters for session resumption can also
2501 * be set explicitly with `br_ssl_engine_set_session_parameters()`.
2502 *
2503 * On failure, the context is marked as failed, and this function
2504 * returns 0. A possible failure condition is when no initial entropy
2505 * was injected, and none could be obtained from the OS (either OS
2506 * randomness gathering is not supported, or it failed).
2507 *
2508 * \param cc client context.
2509 * \param server_name target server name, or `NULL`.
2510 * \param resume_session non-zero to try session resumption.
2511 * \return 0 on failure, 1 on success.
2512 */
2513 int br_ssl_client_reset(br_ssl_client_context *cc,
2514 const char *server_name, int resume_session);
2515
2516 /**
2517 * \brief Forget any session in the context.
2518 *
2519 * This means that the next handshake that uses this context will
2520 * necessarily be a full handshake (this applies both to new connections
2521 * and to renegotiations).
2522 *
2523 * \param cc client context.
2524 */
2525 static inline void
2526 br_ssl_client_forget_session(br_ssl_client_context *cc)
2527 {
2528 cc->eng.session.session_id_len = 0;
2529 }
2530
2531 /**
2532 * \brief Set client certificate chain and key (single RSA case).
2533 *
2534 * This function sets a client certificate chain, that the client will
2535 * send to the server whenever a client certificate is requested. This
2536 * certificate uses an RSA public key; the corresponding private key is
2537 * invoked for authentication. Trust anchor names sent by the server are
2538 * ignored.
2539 *
2540 * The provided chain and private key are linked in the client context;
2541 * they must remain valid as long as they may be used, i.e. normally
2542 * for the duration of the connection, since they might be invoked
2543 * again upon renegotiations.
2544 *
2545 * \param cc SSL client context.
2546 * \param chain client certificate chain (SSL order: EE comes first).
2547 * \param chain_len client chain length (number of certificates).
2548 * \param sk client private key.
2549 * \param irsasign RSA signature implementation (PKCS#1 v1.5).
2550 */
2551 void br_ssl_client_set_single_rsa(br_ssl_client_context *cc,
2552 const br_x509_certificate *chain, size_t chain_len,
2553 const br_rsa_private_key *sk, br_rsa_pkcs1_sign irsasign);
2554
2555 /*
2556 * \brief Set the client certificate chain and key (single EC case).
2557 *
2558 * This function sets a client certificate chain, that the client will
2559 * send to the server whenever a client certificate is requested. This
2560 * certificate uses an EC public key; the corresponding private key is
2561 * invoked for authentication. Trust anchor names sent by the server are
2562 * ignored.
2563 *
2564 * The provided chain and private key are linked in the client context;
2565 * they must remain valid as long as they may be used, i.e. normally
2566 * for the duration of the connection, since they might be invoked
2567 * again upon renegotiations.
2568 *
2569 * The `allowed_usages` is a combination of usages, namely
2570 * `BR_KEYTYPE_KEYX` and/or `BR_KEYTYPE_SIGN`. The `BR_KEYTYPE_KEYX`
2571 * value allows full static ECDH, while the `BR_KEYTYPE_SIGN` value
2572 * allows ECDSA signatures. If ECDSA signatures are used, then an ECDSA
2573 * signature implementation must be provided; otherwise, the `iecdsa`
2574 * parameter may be 0.
2575 *
2576 * The `cert_issuer_key_type` value is either `BR_KEYTYPE_RSA` or
2577 * `BR_KEYTYPE_EC`; it is the type of the public key used the the CA
2578 * that issued (signed) the client certificate. That value is used with
2579 * full static ECDH: support of the certificate by the server depends
2580 * on how the certificate was signed. (Note: when using TLS 1.2, this
2581 * parameter is ignored; but its value matters for TLS 1.0 and 1.1.)
2582 *
2583 * \param cc server context.
2584 * \param chain server certificate chain to send.
2585 * \param chain_len chain length (number of certificates).
2586 * \param sk server private key (EC).
2587 * \param allowed_usages allowed private key usages.
2588 * \param cert_issuer_key_type issuing CA's key type.
2589 * \param iec EC core implementation.
2590 * \param iecdsa ECDSA signature implementation ("asn1" format).
2591 */
2592 void br_ssl_client_set_single_ec(br_ssl_client_context *cc,
2593 const br_x509_certificate *chain, size_t chain_len,
2594 const br_ec_private_key *sk, unsigned allowed_usages,
2595 unsigned cert_issuer_key_type,
2596 const br_ec_impl *iec, br_ecdsa_sign iecdsa);
2597
2598 /**
2599 * \brief Type for a "translated cipher suite", as an array of two
2600 * 16-bit integers.
2601 *
2602 * The first element is the cipher suite identifier (as used on the wire).
2603 * The second element is the concatenation of four 4-bit elements which
2604 * characterise the cipher suite contents. In most to least significant
2605 * order, these 4-bit elements are:
2606 *
2607 * - Bits 12 to 15: key exchange + server key type
2608 *
2609 * | val | symbolic constant | suite type | details |
2610 * | :-- | :----------------------- | :---------- | :----------------------------------------------- |
2611 * | 0 | `BR_SSLKEYX_RSA` | RSA | RSA key exchange, key is RSA (encryption) |
2612 * | 1 | `BR_SSLKEYX_ECDHE_RSA` | ECDHE_RSA | ECDHE key exchange, key is RSA (signature) |
2613 * | 2 | `BR_SSLKEYX_ECDHE_ECDSA` | ECDHE_ECDSA | ECDHE key exchange, key is EC (signature) |
2614 * | 3 | `BR_SSLKEYX_ECDH_RSA` | ECDH_RSA | Key is EC (key exchange), cert signed with RSA |
2615 * | 4 | `BR_SSLKEYX_ECDH_ECDSA` | ECDH_ECDSA | Key is EC (key exchange), cert signed with ECDSA |
2616 *
2617 * - Bits 8 to 11: symmetric encryption algorithm
2618 *
2619 * | val | symbolic constant | symmetric encryption | key strength (bits) |
2620 * | :-- | :--------------------- | :------------------- | :------------------ |
2621 * | 0 | `BR_SSLENC_3DES_CBC` | 3DES/CBC | 168 |
2622 * | 1 | `BR_SSLENC_AES128_CBC` | AES-128/CBC | 128 |
2623 * | 2 | `BR_SSLENC_AES256_CBC` | AES-256/CBC | 256 |
2624 * | 3 | `BR_SSLENC_AES128_GCM` | AES-128/GCM | 128 |
2625 * | 4 | `BR_SSLENC_AES256_GCM` | AES-256/GCM | 256 |
2626 * | 5 | `BR_SSLENC_CHACHA20` | ChaCha20/Poly1305 | 256 |
2627 *
2628 * - Bits 4 to 7: MAC algorithm
2629 *
2630 * | val | symbolic constant | MAC type | details |
2631 * | :-- | :----------------- | :----------- | :------------------------------------ |
2632 * | 0 | `BR_SSLMAC_AEAD` | AEAD | No dedicated MAC (encryption is AEAD) |
2633 * | 2 | `BR_SSLMAC_SHA1` | HMAC/SHA-1 | Value matches `br_sha1_ID` |
2634 * | 4 | `BR_SSLMAC_SHA256` | HMAC/SHA-256 | Value matches `br_sha256_ID` |
2635 * | 5 | `BR_SSLMAC_SHA384` | HMAC/SHA-384 | Value matches `br_sha384_ID` |
2636 *
2637 * - Bits 0 to 3: hash function for PRF when used with TLS-1.2
2638 *
2639 * | val | symbolic constant | hash function | details |
2640 * | :-- | :----------------- | :------------ | :----------------------------------- |
2641 * | 4 | `BR_SSLPRF_SHA256` | SHA-256 | Value matches `br_sha256_ID` |
2642 * | 5 | `BR_SSLPRF_SHA384` | SHA-384 | Value matches `br_sha384_ID` |
2643 *
2644 * For instance, cipher suite `TLS_RSA_WITH_AES_128_GCM_SHA256` has
2645 * standard identifier 0x009C, and is translated to 0x0304, for, in
2646 * that order: RSA key exchange (0), AES-128/GCM (3), AEAD integrity (0),
2647 * SHA-256 in the TLS PRF (4).
2648 */
2649 typedef uint16_t br_suite_translated[2];
2650
2651 #ifndef BR_DOXYGEN_IGNORE
2652 /*
2653 * Constants are already documented in the br_suite_translated type.
2654 */
2655
2656 #define BR_SSLKEYX_RSA 0
2657 #define BR_SSLKEYX_ECDHE_RSA 1
2658 #define BR_SSLKEYX_ECDHE_ECDSA 2
2659 #define BR_SSLKEYX_ECDH_RSA 3
2660 #define BR_SSLKEYX_ECDH_ECDSA 4
2661
2662 #define BR_SSLENC_3DES_CBC 0
2663 #define BR_SSLENC_AES128_CBC 1
2664 #define BR_SSLENC_AES256_CBC 2
2665 #define BR_SSLENC_AES128_GCM 3
2666 #define BR_SSLENC_AES256_GCM 4
2667 #define BR_SSLENC_CHACHA20 5
2668
2669 #define BR_SSLMAC_AEAD 0
2670 #define BR_SSLMAC_SHA1 br_sha1_ID
2671 #define BR_SSLMAC_SHA256 br_sha256_ID
2672 #define BR_SSLMAC_SHA384 br_sha384_ID
2673
2674 #define BR_SSLPRF_SHA256 br_sha256_ID
2675 #define BR_SSLPRF_SHA384 br_sha384_ID
2676
2677 #endif
2678
2679 /*
2680 * Pre-declaration for the SSL server context.
2681 */
2682 typedef struct br_ssl_server_context_ br_ssl_server_context;
2683
2684 /**
2685 * \brief Type for the server policy choices, taken after analysis of
2686 * the client message (ClientHello).
2687 */
2688 typedef struct {
2689 /**
2690 * \brief Cipher suite to use with that client.
2691 */
2692 uint16_t cipher_suite;
2693
2694 /**
2695 * \brief Hash function or algorithm for signing the ServerKeyExchange.
2696 *
2697 * This parameter is ignored for `TLS_RSA_*` and `TLS_ECDH_*`
2698 * cipher suites; it is used only for `TLS_ECDHE_*` suites, in
2699 * which the server _signs_ the ephemeral EC Diffie-Hellman
2700 * parameters sent to the client.
2701 *
2702 * This identifier must be one of the following values:
2703 *
2704 * - `0xFF00 + id`, where `id` is a hash function identifier
2705 * (0 for MD5+SHA-1, or 2 to 6 for one of the SHA functions);
2706 *
2707 * - a full 16-bit identifier, lower than `0xFF00`.
2708 *
2709 * If the first option is used, then the SSL engine will
2710 * compute the hash of the data that is to be signed, with the
2711 * designated hash function. The `do_sign()` method will be
2712 * invoked with that hash value provided in the the `data`
2713 * buffer.
2714 *
2715 * If the second option is used, then the SSL engine will NOT
2716 * compute a hash on the data; instead, it will provide the
2717 * to-be-signed data itself in `data`, i.e. the concatenation of
2718 * the client random, server random, and encoded ECDH
2719 * parameters. Furthermore, with TLS-1.2 and later, the 16-bit
2720 * identifier will be used "as is" in the protocol, in the
2721 * SignatureAndHashAlgorithm; for instance, `0x0401` stands for
2722 * RSA PKCS#1 v1.5 signature (the `01`) with SHA-256 as hash
2723 * function (the `04`).
2724 *
2725 * Take care that with TLS 1.0 and 1.1, the hash function is
2726 * constrainted by the protocol: RSA signature must use
2727 * MD5+SHA-1 (so use `0xFF00`), while ECDSA must use SHA-1
2728 * (`0xFF02`). Since TLS 1.0 and 1.1 don't include a
2729 * SignatureAndHashAlgorithm field in their ServerKeyExchange
2730 * messages, any value below `0xFF00` will be usable to send the
2731 * raw ServerKeyExchange data to the `do_sign()` callback, but
2732 * that callback must still follow the protocol requirements
2733 * when generating the signature.
2734 */
2735 unsigned algo_id;
2736
2737 /**
2738 * \brief Certificate chain to send to the client.
2739 *
2740 * This is an array of `br_x509_certificate` objects, each
2741 * normally containing a DER-encoded certificate. The server
2742 * code does not try to decode these elements.
2743 */
2744 const br_x509_certificate *chain;
2745
2746 /**
2747 * \brief Certificate chain length (number of certificates).
2748 */
2749 size_t chain_len;
2750
2751 } br_ssl_server_choices;
2752
2753 /**
2754 * \brief Class type for a policy handler (server side).
2755 *
2756 * A policy handler selects the policy parameters for a connection
2757 * (cipher suite and other algorithms, and certificate chain to send to
2758 * the client); it also performs the server-side computations involving
2759 * its permanent private key.
2760 *
2761 * The SSL server engine will invoke first `choose()`, once the
2762 * ClientHello message has been received, then either `do_keyx()`
2763 * `do_sign()`, depending on the cipher suite.
2764 */
2765 typedef struct br_ssl_server_policy_class_ br_ssl_server_policy_class;
2766 struct br_ssl_server_policy_class_ {
2767 /**
2768 * \brief Context size (in bytes).
2769 */
2770 size_t context_size;
2771
2772 /**
2773 * \brief Select algorithms and certificates for this connection.
2774 *
2775 * This callback function shall fill the provided `choices`
2776 * structure with the policy choices for this connection. This
2777 * entails selecting the cipher suite, hash function for signing
2778 * the ServerKeyExchange (applicable only to ECDHE cipher suites),
2779 * and certificate chain to send.
2780 *
2781 * The callback receives a pointer to the server context that
2782 * contains the relevant data. In particular, the functions
2783 * `br_ssl_server_get_client_suites()`,
2784 * `br_ssl_server_get_client_hashes()` and
2785 * `br_ssl_server_get_client_curves()` can be used to obtain
2786 * the cipher suites, hash functions and elliptic curves
2787 * supported by both the client and server, respectively. The
2788 * `br_ssl_engine_get_version()` and `br_ssl_engine_get_server_name()`
2789 * functions yield the protocol version and requested server name
2790 * (SNI), respectively.
2791 *
2792 * This function may modify its context structure (`pctx`) in
2793 * arbitrary ways to keep track of its own choices.
2794 *
2795 * This function shall return 1 if appropriate policy choices
2796 * could be made, or 0 if this connection cannot be pursued.
2797 *
2798 * \param pctx policy context.
2799 * \param cc SSL server context.
2800 * \param choices destination structure for the policy choices.
2801 * \return 1 on success, 0 on error.
2802 */
2803 int (*choose)(const br_ssl_server_policy_class **pctx,
2804 const br_ssl_server_context *cc,
2805 br_ssl_server_choices *choices);
2806
2807 /**
2808 * \brief Perform key exchange (server part).
2809 *
2810 * This callback is invoked to perform the server-side cryptographic
2811 * operation for a key exchange that is not ECDHE. This callback
2812 * uses the private key.
2813 *
2814 * **For RSA key exchange**, the provided `data` (of length `*len`
2815 * bytes) shall be decrypted with the server's private key, and
2816 * the 48-byte premaster secret copied back to the first 48 bytes
2817 * of `data`.
2818 *
2819 * - The caller makes sure that `*len` is at least 59 bytes.
2820 *
2821 * - This callback MUST check that the provided length matches
2822 * that of the key modulus; it shall report an error otherwise.
2823 *
2824 * - If the length matches that of the RSA key modulus, then
2825 * processing MUST be constant-time, even if decryption fails,
2826 * or the padding is incorrect, or the plaintext message length
2827 * is not exactly 48 bytes.
2828 *
2829 * - This callback needs not check the two first bytes of the
2830 * obtained pre-master secret (the caller will do that).
2831 *
2832 * - If an error is reported (0), then what the callback put
2833 * in the first 48 bytes of `data` is unimportant (the caller
2834 * will use random bytes instead).
2835 *
2836 * **For ECDH key exchange**, the provided `data` (of length `*len`
2837 * bytes) is the elliptic curve point from the client. The
2838 * callback shall multiply it with its private key, and store
2839 * the resulting X coordinate in `data`, starting at offset 0,
2840 * and set `*len` to the length of the X coordinate.
2841 *
2842 * - If the input array does not have the proper length for
2843 * an encoded curve point, then an error (0) shall be reported.
2844 *
2845 * - If the input array has the proper length, then processing
2846 * MUST be constant-time, even if the data is not a valid
2847 * encoded point.
2848 *
2849 * - This callback MUST check that the input point is valid.
2850 *
2851 * Returned value is 1 on success, 0 on error.
2852 *
2853 * \param pctx policy context.
2854 * \param data key exchange data from the client.
2855 * \param len key exchange data length (in bytes).
2856 * \return 1 on success, 0 on error.
2857 */
2858 uint32_t (*do_keyx)(const br_ssl_server_policy_class **pctx,
2859 unsigned char *data, size_t *len);
2860
2861 /**
2862 * \brief Perform a signature (for a ServerKeyExchange message).
2863 *
2864 * This callback function is invoked for ECDHE cipher suites. On
2865 * input, the hash value or message to sign is in `data`, of
2866 * size `hv_len`; the involved hash function or algorithm is
2867 * identified by `algo_id`. The signature shall be computed and
2868 * written back into `data`; the total size of that buffer is
2869 * `len` bytes.
2870 *
2871 * This callback shall verify that the signature length does not
2872 * exceed `len` bytes, and abstain from writing the signature if
2873 * it does not fit.
2874 *
2875 * The `algo_id` value matches that which was written in the
2876 * `choices` structures by the `choose()` callback. This will be
2877 * one of the following:
2878 *
2879 * - `0xFF00 + id` for a hash function identifier `id`. In
2880 * that case, the `data` buffer contains a hash value
2881 * already computed over the data that is to be signed,
2882 * of length `hv_len`. The `id` may be 0 to designate the
2883 * special MD5+SHA-1 concatenation (old-style RSA signing).
2884 *
2885 * - Another value, lower than `0xFF00`. The `data` buffer
2886 * then contains the raw, non-hashed data to be signed
2887 * (concatenation of the client and server randoms and
2888 * ECDH parameters). The callback is responsible to apply
2889 * any relevant hashing as part of the signing process.
2890 *
2891 * Returned value is the signature length (in bytes), or 0 on error.
2892 *
2893 * \param pctx policy context.
2894 * \param algo_id hash function / algorithm identifier.
2895 * \param data input/output buffer (message/hash, then signature).
2896 * \param hv_len hash value or message length (in bytes).
2897 * \param len total buffer length (in bytes).
2898 * \return signature length (in bytes) on success, or 0 on error.
2899 */
2900 size_t (*do_sign)(const br_ssl_server_policy_class **pctx,
2901 unsigned algo_id,
2902 unsigned char *data, size_t hv_len, size_t len);
2903 };
2904
2905 /**
2906 * \brief A single-chain RSA policy handler.
2907 *
2908 * This policy context uses a single certificate chain, and a RSA
2909 * private key. The context can be restricted to only signatures or
2910 * only key exchange.
2911 *
2912 * Apart from the first field (vtable pointer), its contents are
2913 * opaque and shall not be accessed directly.
2914 */
2915 typedef struct {
2916 /** \brief Pointer to vtable. */
2917 const br_ssl_server_policy_class *vtable;
2918 #ifndef BR_DOXYGEN_IGNORE
2919 const br_x509_certificate *chain;
2920 size_t chain_len;
2921 const br_rsa_private_key *sk;
2922 unsigned allowed_usages;
2923 br_rsa_private irsacore;
2924 br_rsa_pkcs1_sign irsasign;
2925 #endif
2926 } br_ssl_server_policy_rsa_context;
2927
2928 /**
2929 * \brief A single-chain EC policy handler.
2930 *
2931 * This policy context uses a single certificate chain, and an EC
2932 * private key. The context can be restricted to only signatures or
2933 * only key exchange.
2934 *
2935 * Due to how TLS is defined, this context must be made aware whether
2936 * the server certificate was itself signed with RSA or ECDSA. The code
2937 * does not try to decode the certificate to obtain that information.
2938 *
2939 * Apart from the first field (vtable pointer), its contents are
2940 * opaque and shall not be accessed directly.
2941 */
2942 typedef struct {
2943 /** \brief Pointer to vtable. */
2944 const br_ssl_server_policy_class *vtable;
2945 #ifndef BR_DOXYGEN_IGNORE
2946 const br_x509_certificate *chain;
2947 size_t chain_len;
2948 const br_ec_private_key *sk;
2949 unsigned allowed_usages;
2950 unsigned cert_issuer_key_type;
2951 const br_multihash_context *mhash;
2952 const br_ec_impl *iec;
2953 br_ecdsa_sign iecdsa;
2954 #endif
2955 } br_ssl_server_policy_ec_context;
2956
2957 /**
2958 * \brief Class type for a session parameter cache.
2959 *
2960 * Session parameters are saved in the cache with `save()`, and
2961 * retrieved with `load()`. The cache implementation can apply any
2962 * storage and eviction strategy that it sees fit. The SSL server
2963 * context that performs the request is provided, so that its
2964 * functionalities may be used by the implementation (e.g. hash
2965 * functions or random number generation).
2966 */
2967 typedef struct br_ssl_session_cache_class_ br_ssl_session_cache_class;
2968 struct br_ssl_session_cache_class_ {
2969 /**
2970 * \brief Context size (in bytes).
2971 */
2972 size_t context_size;
2973
2974 /**
2975 * \brief Record a session.
2976 *
2977 * This callback should record the provided session parameters.
2978 * The `params` structure is transient, so its contents shall
2979 * be copied into the cache. The session ID has been randomly
2980 * generated and always has length exactly 32 bytes.
2981 *
2982 * \param ctx session cache context.
2983 * \param server_ctx SSL server context.
2984 * \param params session parameters to save.
2985 */
2986 void (*save)(const br_ssl_session_cache_class **ctx,
2987 br_ssl_server_context *server_ctx,
2988 const br_ssl_session_parameters *params);
2989
2990 /**
2991 * \brief Lookup a session in the cache.
2992 *
2993 * The session ID to lookup is in `params` and always has length
2994 * exactly 32 bytes. If the session parameters are found in the
2995 * cache, then the parameters shall be copied into the `params`
2996 * structure. Returned value is 1 on successful lookup, 0
2997 * otherwise.
2998 *
2999 * \param ctx session cache context.
3000 * \param server_ctx SSL server context.
3001 * \param params destination for session parameters.
3002 * \return 1 if found, 0 otherwise.
3003 */
3004 int (*load)(const br_ssl_session_cache_class **ctx,
3005 br_ssl_server_context *server_ctx,
3006 br_ssl_session_parameters *params);
3007 };
3008
3009 /**
3010 * \brief Context for a basic cache system.
3011 *
3012 * The system stores session parameters in a buffer provided at
3013 * initialisation time. Each entry uses exactly 100 bytes, and
3014 * buffer sizes up to 4294967295 bytes are supported.
3015 *
3016 * Entries are evicted with a LRU (Least Recently Used) policy. A
3017 * search tree is maintained to keep lookups fast even with large
3018 * caches.
3019 *
3020 * Apart from the first field (vtable pointer), the structure
3021 * contents are opaque and shall not be accessed directly.
3022 */
3023 typedef struct {
3024 /** \brief Pointer to vtable. */
3025 const br_ssl_session_cache_class *vtable;
3026 #ifndef BR_DOXYGEN_IGNORE
3027 unsigned char *store;
3028 size_t store_len, store_ptr;
3029 unsigned char index_key[32];
3030 const br_hash_class *hash;
3031 int init_done;
3032 uint32_t head, tail, root;
3033 #endif
3034 } br_ssl_session_cache_lru;
3035
3036 /**
3037 * \brief Initialise a LRU session cache with the provided storage space.
3038 *
3039 * The provided storage space must remain valid as long as the cache
3040 * is used. Arbitrary lengths are supported, up to 4294967295 bytes;
3041 * each entry uses up exactly 100 bytes.
3042 *
3043 * \param cc session cache context.
3044 * \param store storage space for cached entries.
3045 * \param store_len storage space length (in bytes).
3046 */
3047 void br_ssl_session_cache_lru_init(br_ssl_session_cache_lru *cc,
3048 unsigned char *store, size_t store_len);
3049
3050 /**
3051 * \brief Context structure for a SSL server.
3052 *
3053 * The first field (called `eng`) is the SSL engine; all functions that
3054 * work on a `br_ssl_engine_context` structure shall take as parameter
3055 * a pointer to that field. The other structure fields are opaque and
3056 * must not be accessed directly.
3057 */
3058 struct br_ssl_server_context_ {
3059 /**
3060 * \brief The encapsulated engine context.
3061 */
3062 br_ssl_engine_context eng;
3063
3064 #ifndef BR_DOXYGEN_IGNORE
3065 /*
3066 * Maximum version from the client.
3067 */
3068 uint16_t client_max_version;
3069
3070 /*
3071 * Session cache.
3072 */
3073 const br_ssl_session_cache_class **cache_vtable;
3074
3075 /*
3076 * Translated cipher suites supported by the client. The list
3077 * is trimmed to include only the cipher suites that the
3078 * server also supports; they are in the same order as in the
3079 * client message.
3080 */
3081 br_suite_translated client_suites[BR_MAX_CIPHER_SUITES];
3082 unsigned char client_suites_num;
3083
3084 /*
3085 * Hash functions supported by the client, with ECDSA and RSA
3086 * (bit mask). For hash function with id 'x', set bit index is
3087 * x for RSA, x+8 for ECDSA. For newer algorithms, with ID
3088 * 0x08**, bit 16+k is set for algorithm 0x0800+k.
3089 */
3090 uint32_t hashes;
3091
3092 /*
3093 * Curves supported by the client (bit mask, for named curves).
3094 */
3095 uint32_t curves;
3096
3097 /*
3098 * Context for chain handler.
3099 */
3100 const br_ssl_server_policy_class **policy_vtable;
3101 uint16_t sign_hash_id;
3102
3103 /*
3104 * For the core handlers, thus avoiding (in most cases) the
3105 * need for an externally provided policy context.
3106 */
3107 union {
3108 const br_ssl_server_policy_class *vtable;
3109 br_ssl_server_policy_rsa_context single_rsa;
3110 br_ssl_server_policy_ec_context single_ec;
3111 } chain_handler;
3112
3113 /*
3114 * Buffer for the ECDHE private key.
3115 */
3116 unsigned char ecdhe_key[70];
3117 size_t ecdhe_key_len;
3118
3119 /*
3120 * Trust anchor names for client authentication. "ta_names" and
3121 * "tas" cannot be both non-NULL.
3122 */
3123 const br_x500_name *ta_names;
3124 const br_x509_trust_anchor *tas;
3125 size_t num_tas;
3126 size_t cur_dn_index;
3127 const unsigned char *cur_dn;
3128 size_t cur_dn_len;
3129
3130 /*
3131 * Buffer for the hash value computed over all handshake messages
3132 * prior to CertificateVerify, and identifier for the hash function.
3133 */
3134 unsigned char hash_CV[64];
3135 size_t hash_CV_len;
3136 int hash_CV_id;
3137
3138 /*
3139 * Server-specific implementations.
3140 * (none for now)
3141 */
3142 #endif
3143 };
3144
3145 /*
3146 * Each br_ssl_server_init_xxx() function sets the list of supported
3147 * cipher suites and used implementations, as specified by the profile
3148 * name 'xxx'. Defined profile names are:
3149 *
3150 * full_rsa all supported algorithm, server key type is RSA
3151 * full_ec all supported algorithm, server key type is EC
3152 * TODO: add other profiles
3153 *
3154 * Naming scheme for "minimal" profiles: min123
3155 *
3156 * -- character 1: key exchange
3157 * r = RSA
3158 * e = ECDHE_RSA
3159 * f = ECDHE_ECDSA
3160 * u = ECDH_RSA
3161 * v = ECDH_ECDSA
3162 * -- character 2: version / PRF
3163 * 0 = TLS 1.0 / 1.1 with MD5+SHA-1
3164 * 2 = TLS 1.2 with SHA-256
3165 * 3 = TLS 1.2 with SHA-384
3166 * -- character 3: encryption
3167 * a = AES/CBC
3168 * g = AES/GCM
3169 * d = 3DES/CBC
3170 */
3171
3172 /**
3173 * \brief SSL server profile: full_rsa.
3174 *
3175 * This function initialises the provided SSL server context with
3176 * all supported algorithms and cipher suites that rely on a RSA
3177 * key pair.
3178 *
3179 * \param cc server context to initialise.
3180 * \param chain server certificate chain.
3181 * \param chain_len certificate chain length (number of certificate).
3182 * \param sk RSA private key.
3183 */
3184 void br_ssl_server_init_full_rsa(br_ssl_server_context *cc,
3185 const br_x509_certificate *chain, size_t chain_len,
3186 const br_rsa_private_key *sk);
3187
3188 /**
3189 * \brief SSL server profile: full_ec.
3190 *
3191 * This function initialises the provided SSL server context with
3192 * all supported algorithms and cipher suites that rely on an EC
3193 * key pair.
3194 *
3195 * The key type of the CA that issued the server's certificate must
3196 * be provided, since it matters for ECDH cipher suites (ECDH_RSA
3197 * suites require a RSA-powered CA). The key type is either
3198 * `BR_KEYTYPE_RSA` or `BR_KEYTYPE_EC`.
3199 *
3200 * \param cc server context to initialise.
3201 * \param chain server certificate chain.
3202 * \param chain_len chain length (number of certificates).
3203 * \param cert_issuer_key_type certificate issuer's key type.
3204 * \param sk EC private key.
3205 */
3206 void br_ssl_server_init_full_ec(br_ssl_server_context *cc,
3207 const br_x509_certificate *chain, size_t chain_len,
3208 unsigned cert_issuer_key_type, const br_ec_private_key *sk);
3209
3210 /**
3211 * \brief SSL server profile: minr2g.
3212 *
3213 * This profile uses only TLS_RSA_WITH_AES_128_GCM_SHA256. Server key is
3214 * RSA, and RSA key exchange is used (not forward secure, but uses little
3215 * CPU in the client).
3216 *
3217 * \param cc server context to initialise.
3218 * \param chain server certificate chain.
3219 * \param chain_len certificate chain length (number of certificate).
3220 * \param sk RSA private key.
3221 */
3222 void br_ssl_server_init_minr2g(br_ssl_server_context *cc,
3223 const br_x509_certificate *chain, size_t chain_len,
3224 const br_rsa_private_key *sk);
3225
3226 /**
3227 * \brief SSL server profile: mine2g.
3228 *
3229 * This profile uses only TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256. Server key
3230 * is RSA, and ECDHE key exchange is used. This suite provides forward
3231 * security, with a higher CPU expense on the client, and a somewhat
3232 * larger code footprint (compared to "minr2g").
3233 *
3234 * \param cc server context to initialise.
3235 * \param chain server certificate chain.
3236 * \param chain_len certificate chain length (number of certificate).
3237 * \param sk RSA private key.
3238 */
3239 void br_ssl_server_init_mine2g(br_ssl_server_context *cc,
3240 const br_x509_certificate *chain, size_t chain_len,
3241 const br_rsa_private_key *sk);
3242
3243 /**
3244 * \brief SSL server profile: minf2g.
3245 *
3246 * This profile uses only TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256.
3247 * Server key is EC, and ECDHE key exchange is used. This suite provides
3248 * forward security, with a higher CPU expense on the client and server
3249 * (by a factor of about 3 to 4), and a somewhat larger code footprint
3250 * (compared to "minu2g" and "minv2g").
3251 *
3252 * \param cc server context to initialise.
3253 * \param chain server certificate chain.
3254 * \param chain_len certificate chain length (number of certificate).
3255 * \param sk EC private key.
3256 */
3257 void br_ssl_server_init_minf2g(br_ssl_server_context *cc,
3258 const br_x509_certificate *chain, size_t chain_len,
3259 const br_ec_private_key *sk);
3260
3261 /**
3262 * \brief SSL server profile: minu2g.
3263 *
3264 * This profile uses only TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256.
3265 * Server key is EC, and ECDH key exchange is used; the issuing CA used
3266 * a RSA key.
3267 *
3268 * The "minu2g" and "minv2g" profiles do not provide forward secrecy,
3269 * but are the lightest on the server (for CPU usage), and are rather
3270 * inexpensive on the client as well.
3271 *
3272 * \param cc server context to initialise.
3273 * \param chain server certificate chain.
3274 * \param chain_len certificate chain length (number of certificate).
3275 * \param sk EC private key.
3276 */
3277 void br_ssl_server_init_minu2g(br_ssl_server_context *cc,
3278 const br_x509_certificate *chain, size_t chain_len,
3279 const br_ec_private_key *sk);
3280
3281 /**
3282 * \brief SSL server profile: minv2g.
3283 *
3284 * This profile uses only TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256.
3285 * Server key is EC, and ECDH key exchange is used; the issuing CA used
3286 * an EC key.
3287 *
3288 * The "minu2g" and "minv2g" profiles do not provide forward secrecy,
3289 * but are the lightest on the server (for CPU usage), and are rather
3290 * inexpensive on the client as well.
3291 *
3292 * \param cc server context to initialise.
3293 * \param chain server certificate chain.
3294 * \param chain_len certificate chain length (number of certificate).
3295 * \param sk EC private key.
3296 */
3297 void br_ssl_server_init_minv2g(br_ssl_server_context *cc,
3298 const br_x509_certificate *chain, size_t chain_len,
3299 const br_ec_private_key *sk);
3300
3301 /**
3302 * \brief SSL server profile: mine2c.
3303 *
3304 * This profile uses only TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256.
3305 * Server key is RSA, and ECDHE key exchange is used. This suite
3306 * provides forward security.
3307 *
3308 * \param cc server context to initialise.
3309 * \param chain server certificate chain.
3310 * \param chain_len certificate chain length (number of certificate).
3311 * \param sk RSA private key.
3312 */
3313 void br_ssl_server_init_mine2c(br_ssl_server_context *cc,
3314 const br_x509_certificate *chain, size_t chain_len,
3315 const br_rsa_private_key *sk);
3316
3317 /**
3318 * \brief SSL server profile: minf2c.
3319 *
3320 * This profile uses only TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256.
3321 * Server key is EC, and ECDHE key exchange is used. This suite provides
3322 * forward security.
3323 *
3324 * \param cc server context to initialise.
3325 * \param chain server certificate chain.
3326 * \param chain_len certificate chain length (number of certificate).
3327 * \param sk EC private key.
3328 */
3329 void br_ssl_server_init_minf2c(br_ssl_server_context *cc,
3330 const br_x509_certificate *chain, size_t chain_len,
3331 const br_ec_private_key *sk);
3332
3333 /**
3334 * \brief Get the supported client suites.
3335 *
3336 * This function shall be called only after the ClientHello has been
3337 * processed, typically from the policy engine. The returned array
3338 * contains the cipher suites that are supported by both the client
3339 * and the server; these suites are in client preference order, unless
3340 * the `BR_OPT_ENFORCE_SERVER_PREFERENCES` flag was set, in which case
3341 * they are in server preference order.
3342 *
3343 * The suites are _translated_, which means that each suite is given
3344 * as two 16-bit integers: the standard suite identifier, and its
3345 * translated version, broken down into its individual components,
3346 * as explained with the `br_suite_translated` type.
3347 *
3348 * The returned array is allocated in the context and will be rewritten
3349 * by each handshake.
3350 *
3351 * \param cc server context.
3352 * \param num receives the array size (number of suites).
3353 * \return the translated common cipher suites, in preference order.
3354 */
3355 static inline const br_suite_translated *
3356 br_ssl_server_get_client_suites(const br_ssl_server_context *cc, size_t *num)
3357 {
3358 *num = cc->client_suites_num;
3359 return cc->client_suites;
3360 }
3361
3362 /**
3363 * \brief Get the hash functions and signature algorithms supported by
3364 * the client.
3365 *
3366 * This value is a bit field:
3367 *
3368 * - If RSA (PKCS#1 v1.5) is supported with hash function of ID `x`,
3369 * then bit `x` is set (hash function ID is 0 for the special MD5+SHA-1,
3370 * or 2 to 6 for the SHA family).
3371 *
3372 * - If ECDSA is suported with hash function of ID `x`, then bit `8+x`
3373 * is set.
3374 *
3375 * - Newer algorithms are symbolic 16-bit identifiers that do not
3376 * represent signature algorithm and hash function separately. If
3377 * the TLS-level identifier is `0x0800+x` for a `x` in the 0..15
3378 * range, then bit `16+x` is set.
3379 *
3380 * "New algorithms" are currently defined only in draft documents, so
3381 * this support is subject to possible change. Right now (early 2017),
3382 * this maps ed25519 (EdDSA on Curve25519) to bit 23, and ed448 (EdDSA
3383 * on Curve448) to bit 24. If the identifiers on the wire change in
3384 * future document, then the decoding mechanism in BearSSL will be
3385 * amended to keep mapping ed25519 and ed448 on bits 23 and 24,
3386 * respectively. Mapping of other new algorithms (e.g. RSA/PSS) is not
3387 * guaranteed yet.
3388 *
3389 * \param cc server context.
3390 * \return the client-supported hash functions and signature algorithms.
3391 */
3392 static inline uint32_t
3393 br_ssl_server_get_client_hashes(const br_ssl_server_context *cc)
3394 {
3395 return cc->hashes;
3396 }
3397
3398 /**
3399 * \brief Get the elliptic curves supported by the client.
3400 *
3401 * This is a bit field (bit x is set if curve of ID x is supported).
3402 *
3403 * \param cc server context.
3404 * \return the client-supported elliptic curves.
3405 */
3406 static inline uint32_t
3407 br_ssl_server_get_client_curves(const br_ssl_server_context *cc)
3408 {
3409 return cc->curves;
3410 }
3411
3412 /**
3413 * \brief Clear the complete contents of a SSL server context.
3414 *
3415 * Everything is cleared, including the reference to the configured buffer,
3416 * implementations, cipher suites and state. This is a preparatory step
3417 * to assembling a custom profile.
3418 *
3419 * \param cc server context to clear.
3420 */
3421 void br_ssl_server_zero(br_ssl_server_context *cc);
3422
3423 /**
3424 * \brief Set an externally provided policy context.
3425 *
3426 * The policy context's methods are invoked to decide the cipher suite
3427 * and certificate chain, and to perform operations involving the server's
3428 * private key.
3429 *
3430 * \param cc server context.
3431 * \param pctx policy context (pointer to its vtable field).
3432 */
3433 static inline void
3434 br_ssl_server_set_policy(br_ssl_server_context *cc,
3435 const br_ssl_server_policy_class **pctx)
3436 {
3437 cc->policy_vtable = pctx;
3438 }
3439
3440 /**
3441 * \brief Set the server certificate chain and key (single RSA case).
3442 *
3443 * This function uses a policy context included in the server context.
3444 * It configures use of a single server certificate chain with a RSA
3445 * private key. The `allowed_usages` is a combination of usages, namely
3446 * `BR_KEYTYPE_KEYX` and/or `BR_KEYTYPE_SIGN`; this enables or disables
3447 * the corresponding cipher suites (i.e. `TLS_RSA_*` use the RSA key for
3448 * key exchange, while `TLS_ECDHE_RSA_*` use the RSA key for signatures).
3449 *
3450 * \param cc server context.
3451 * \param chain server certificate chain to send to the client.
3452 * \param chain_len chain length (number of certificates).
3453 * \param sk server private key (RSA).
3454 * \param allowed_usages allowed private key usages.
3455 * \param irsacore RSA core implementation.
3456 * \param irsasign RSA signature implementation (PKCS#1 v1.5).
3457 */
3458 void br_ssl_server_set_single_rsa(br_ssl_server_context *cc,
3459 const br_x509_certificate *chain, size_t chain_len,
3460 const br_rsa_private_key *sk, unsigned allowed_usages,
3461 br_rsa_private irsacore, br_rsa_pkcs1_sign irsasign);
3462
3463 /**
3464 * \brief Set the server certificate chain and key (single EC case).
3465 *
3466 * This function uses a policy context included in the server context.
3467 * It configures use of a single server certificate chain with an EC
3468 * private key. The `allowed_usages` is a combination of usages, namely
3469 * `BR_KEYTYPE_KEYX` and/or `BR_KEYTYPE_SIGN`; this enables or disables
3470 * the corresponding cipher suites (i.e. `TLS_ECDH_*` use the EC key for
3471 * key exchange, while `TLS_ECDHE_ECDSA_*` use the EC key for signatures).
3472 *
3473 * In order to support `TLS_ECDH_*` cipher suites (non-ephemeral ECDH),
3474 * the algorithm type of the key used by the issuing CA to sign the
3475 * server's certificate must be provided, as `cert_issuer_key_type`
3476 * parameter (this value is either `BR_KEYTYPE_RSA` or `BR_KEYTYPE_EC`).
3477 *
3478 * \param cc server context.
3479 * \param chain server certificate chain to send.
3480 * \param chain_len chain length (number of certificates).
3481 * \param sk server private key (EC).
3482 * \param allowed_usages allowed private key usages.
3483 * \param cert_issuer_key_type issuing CA's key type.
3484 * \param iec EC core implementation.
3485 * \param iecdsa ECDSA signature implementation ("asn1" format).
3486 */
3487 void br_ssl_server_set_single_ec(br_ssl_server_context *cc,
3488 const br_x509_certificate *chain, size_t chain_len,
3489 const br_ec_private_key *sk, unsigned allowed_usages,
3490 unsigned cert_issuer_key_type,
3491 const br_ec_impl *iec, br_ecdsa_sign iecdsa);
3492
3493 /**
3494 * \brief Activate client certificate authentication.
3495 *
3496 * The trust anchor encoded X.500 names (DN) to send to the client are
3497 * provided. A client certificate will be requested and validated through
3498 * the X.509 validator configured in the SSL engine. If `num` is 0, then
3499 * client certificate authentication is disabled.
3500 *
3501 * If the client does not send a certificate, or on validation failure,
3502 * the handshake aborts. Unauthenticated clients can be tolerated by
3503 * setting the `BR_OPT_TOLERATE_NO_CLIENT_AUTH` flag.
3504 *
3505 * The provided array is linked in, not copied, so that pointer must
3506 * remain valid as long as anchor names may be used.
3507 *
3508 * \param cc server context.
3509 * \param ta_names encoded trust anchor names.
3510 * \param num number of encoded trust anchor names.
3511 */
3512 static inline void
3513 br_ssl_server_set_trust_anchor_names(br_ssl_server_context *cc,
3514 const br_x500_name *ta_names, size_t num)
3515 {
3516 cc->ta_names = ta_names;
3517 cc->tas = NULL;
3518 cc->num_tas = num;
3519 }
3520
3521 /**
3522 * \brief Activate client certificate authentication.
3523 *
3524 * This is a variant for `br_ssl_server_set_trust_anchor_names()`: the
3525 * trust anchor names are provided not as an array of stand-alone names
3526 * (`br_x500_name` structures), but as an array of trust anchors
3527 * (`br_x509_trust_anchor` structures). The server engine itself will
3528 * only use the `dn` field of each trust anchor. This is meant to allow
3529 * defining a single array of trust anchors, to be used here and in the
3530 * X.509 validation engine itself.
3531 *
3532 * The provided array is linked in, not copied, so that pointer must
3533 * remain valid as long as anchor names may be used.
3534 *
3535 * \param cc server context.
3536 * \param tas trust anchors (only names are used).
3537 * \param num number of trust anchors.
3538 */
3539 static inline void
3540 br_ssl_server_set_trust_anchor_names_alt(br_ssl_server_context *cc,
3541 const br_x509_trust_anchor *tas, size_t num)
3542 {
3543 cc->ta_names = NULL;
3544 cc->tas = tas;
3545 cc->num_tas = num;
3546 }
3547
3548 /**
3549 * \brief Configure the cache for session parameters.
3550 *
3551 * The cache context is provided as a pointer to its first field (vtable
3552 * pointer).
3553 *
3554 * \param cc server context.
3555 * \param vtable session cache context.
3556 */
3557 static inline void
3558 br_ssl_server_set_cache(br_ssl_server_context *cc,
3559 const br_ssl_session_cache_class **vtable)
3560 {
3561 cc->cache_vtable = vtable;
3562 }
3563
3564 /**
3565 * \brief Prepare or reset a server context for handling an incoming client.
3566 *
3567 * \param cc server context.
3568 * \return 1 on success, 0 on error.
3569 */
3570 int br_ssl_server_reset(br_ssl_server_context *cc);
3571
3572 /* ===================================================================== */
3573
3574 /*
3575 * Context for the simplified I/O context. The transport medium is accessed
3576 * through the low_read() and low_write() callback functions, each with
3577 * its own opaque context pointer.
3578 *
3579 * low_read() read some bytes, at most 'len' bytes, into data[]. The
3580 * returned value is the number of read bytes, or -1 on error.
3581 * The 'len' parameter is guaranteed never to exceed 20000,
3582 * so the length always fits in an 'int' on all platforms.
3583 *
3584 * low_write() write up to 'len' bytes, to be read from data[]. The
3585 * returned value is the number of written bytes, or -1 on
3586 * error. The 'len' parameter is guaranteed never to exceed
3587 * 20000, so the length always fits in an 'int' on all
3588 * parameters.
3589 *
3590 * A socket closure (if the transport medium is a socket) should be reported
3591 * as an error (-1). The callbacks shall endeavour to block until at least
3592 * one byte can be read or written; a callback returning 0 at times is
3593 * acceptable, but this normally leads to the callback being immediately
3594 * called again, so the callback should at least always try to block for
3595 * some time if no I/O can take place.
3596 *
3597 * The SSL engine naturally applies some buffering, so the callbacks need
3598 * not apply buffers of their own.
3599 */
3600 /**
3601 * \brief Context structure for the simplified SSL I/O wrapper.
3602 *
3603 * This structure is initialised with `br_sslio_init()`. Its contents
3604 * are opaque and shall not be accessed directly.
3605 */
3606 typedef struct {
3607 #ifndef BR_DOXYGEN_IGNORE
3608 br_ssl_engine_context *engine;
3609 int (*low_read)(void *read_context,
3610 unsigned char *data, size_t len);
3611 void *read_context;
3612 int (*low_write)(void *write_context,
3613 const unsigned char *data, size_t len);
3614 void *write_context;
3615 #endif
3616 } br_sslio_context;
3617
3618 /**
3619 * \brief Initialise a simplified I/O wrapper context.
3620 *
3621 * The simplified I/O wrapper offers a simpler read/write API for a SSL
3622 * engine (client or server), using the provided callback functions for
3623 * reading data from, or writing data to, the transport medium.
3624 *
3625 * The callback functions have the following semantics:
3626 *
3627 * - Each callback receives an opaque context value (of type `void *`)
3628 * that the callback may use arbitrarily (or possibly ignore).
3629 *
3630 * - `low_read()` reads at least one byte, at most `len` bytes, from
3631 * the transport medium. Read bytes shall be written in `data`.
3632 *
3633 * - `low_write()` writes at least one byte, at most `len` bytes, unto
3634 * the transport medium. The bytes to write are read from `data`.
3635 *
3636 * - The `len` parameter is never zero, and is always lower than 20000.
3637 *
3638 * - The number of processed bytes (read or written) is returned. Since
3639 * that number is less than 20000, it always fits on an `int`.
3640 *
3641 * - On error, the callbacks return -1. Reaching end-of-stream is an
3642 * error. Errors are permanent: the SSL connection is terminated.
3643 *
3644 * - Callbacks SHOULD NOT return 0. This is tolerated, as long as
3645 * callbacks endeavour to block for some non-negligible amount of
3646 * time until at least one byte can be sent or received (if a
3647 * callback returns 0, then the wrapper invokes it again
3648 * immediately).
3649 *
3650 * - Callbacks MAY return as soon as at least one byte is processed;
3651 * they MAY also insist on reading or writing _all_ requested bytes.
3652 * Since SSL is a self-terminated protocol (each record has a length
3653 * header), this does not change semantics.
3654 *
3655 * - Callbacks need not apply any buffering (for performance) since SSL
3656 * itself uses buffers.
3657 *
3658 * \param ctx wrapper context to initialise.
3659 * \param engine SSL engine to wrap.
3660 * \param low_read callback for reading data from the transport.
3661 * \param read_context context pointer for `low_read()`.
3662 * \param low_write callback for writing data on the transport.
3663 * \param write_context context pointer for `low_write()`.
3664 */
3665 void br_sslio_init(br_sslio_context *ctx,
3666 br_ssl_engine_context *engine,
3667 int (*low_read)(void *read_context,
3668 unsigned char *data, size_t len),
3669 void *read_context,
3670 int (*low_write)(void *write_context,
3671 const unsigned char *data, size_t len),
3672 void *write_context);
3673
3674 /**
3675 * \brief Read some application data from a SSL connection.
3676 *
3677 * If `len` is zero, then this function returns 0 immediately. In
3678 * all other cases, it never returns 0.
3679 *
3680 * This call returns only when at least one byte has been obtained.
3681 * Returned value is the number of bytes read, or -1 on error. The
3682 * number of bytes always fits on an 'int' (data from a single SSL/TLS
3683 * record is returned).
3684 *
3685 * On error or SSL closure, this function returns -1. The caller should
3686 * inspect the error status on the SSL engine to distinguish between
3687 * normal closure and error.
3688 *
3689 * \param cc SSL wrapper context.
3690 * \param dst destination buffer for application data.
3691 * \param len maximum number of bytes to obtain.
3692 * \return number of bytes obtained, or -1 on error.
3693 */
3694 int br_sslio_read(br_sslio_context *cc, void *dst, size_t len);
3695
3696 /**
3697 * \brief Read application data from a SSL connection.
3698 *
3699 * This calls returns only when _all_ requested `len` bytes are read,
3700 * or an error is reached. Returned value is 0 on success, -1 on error.
3701 * A normal (verified) SSL closure before that many bytes are obtained
3702 * is reported as an error by this function.
3703 *
3704 * \param cc SSL wrapper context.
3705 * \param dst destination buffer for application data.
3706 * \param len number of bytes to obtain.
3707 * \return 0 on success, or -1 on error.
3708 */
3709 int br_sslio_read_all(br_sslio_context *cc, void *dst, size_t len);
3710
3711 /**
3712 * \brief Write some application data unto a SSL connection.
3713 *
3714 * If `len` is zero, then this function returns 0 immediately. In
3715 * all other cases, it never returns 0.
3716 *
3717 * This call returns only when at least one byte has been written.
3718<