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Fix changing of the cipher state when dealing with early data
[thirdparty/openssl.git] / ssl / tls13_enc.c
1 /*
2 * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 #include <stdlib.h>
11 #include "ssl_locl.h"
12 #include <openssl/evp.h>
13 #include <openssl/kdf.h>
14
15 #define TLS13_MAX_LABEL_LEN 246
16
17 /* Always filled with zeros */
18 static const unsigned char default_zeros[EVP_MAX_MD_SIZE];
19
20 /*
21 * Given a |secret|; a |label| of length |labellen|; and a |hash| of the
22 * handshake messages, derive a new secret |outlen| bytes long and store it in
23 * the location pointed to be |out|. The |hash| value may be NULL. Returns 1 on
24 * success 0 on failure.
25 */
26 int tls13_hkdf_expand(SSL *s, const EVP_MD *md, const unsigned char *secret,
27 const unsigned char *label, size_t labellen,
28 const unsigned char *hash,
29 unsigned char *out, size_t outlen)
30 {
31 const unsigned char label_prefix[] = "TLS 1.3, ";
32 EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
33 int ret;
34 size_t hkdflabellen;
35 size_t hashlen;
36 /*
37 * 2 bytes for length of whole HkdfLabel + 1 byte for length of combined
38 * prefix and label + bytes for the label itself + bytes for the hash
39 */
40 unsigned char hkdflabel[sizeof(uint16_t) + sizeof(uint8_t) +
41 + sizeof(label_prefix) + TLS13_MAX_LABEL_LEN
42 + EVP_MAX_MD_SIZE];
43 WPACKET pkt;
44
45 if (pctx == NULL)
46 return 0;
47
48 hashlen = EVP_MD_size(md);
49
50 if (!WPACKET_init_static_len(&pkt, hkdflabel, sizeof(hkdflabel), 0)
51 || !WPACKET_put_bytes_u16(&pkt, outlen)
52 || !WPACKET_start_sub_packet_u8(&pkt)
53 || !WPACKET_memcpy(&pkt, label_prefix, sizeof(label_prefix) - 1)
54 || !WPACKET_memcpy(&pkt, label, labellen)
55 || !WPACKET_close(&pkt)
56 || !WPACKET_sub_memcpy_u8(&pkt, hash, (hash == NULL) ? 0 : hashlen)
57 || !WPACKET_get_total_written(&pkt, &hkdflabellen)
58 || !WPACKET_finish(&pkt)) {
59 EVP_PKEY_CTX_free(pctx);
60 WPACKET_cleanup(&pkt);
61 return 0;
62 }
63
64 ret = EVP_PKEY_derive_init(pctx) <= 0
65 || EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY)
66 <= 0
67 || EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
68 || EVP_PKEY_CTX_set1_hkdf_key(pctx, secret, hashlen) <= 0
69 || EVP_PKEY_CTX_add1_hkdf_info(pctx, hkdflabel, hkdflabellen) <= 0
70 || EVP_PKEY_derive(pctx, out, &outlen) <= 0;
71
72 EVP_PKEY_CTX_free(pctx);
73
74 return ret == 0;
75 }
76
77 /*
78 * Given a |secret| generate a |key| of length |keylen| bytes. Returns 1 on
79 * success 0 on failure.
80 */
81 int tls13_derive_key(SSL *s, const EVP_MD *md, const unsigned char *secret,
82 unsigned char *key, size_t keylen)
83 {
84 static const unsigned char keylabel[] = "key";
85
86 return tls13_hkdf_expand(s, md, secret, keylabel, sizeof(keylabel) - 1,
87 NULL, key, keylen);
88 }
89
90 /*
91 * Given a |secret| generate an |iv| of length |ivlen| bytes. Returns 1 on
92 * success 0 on failure.
93 */
94 int tls13_derive_iv(SSL *s, const EVP_MD *md, const unsigned char *secret,
95 unsigned char *iv, size_t ivlen)
96 {
97 static const unsigned char ivlabel[] = "iv";
98
99 return tls13_hkdf_expand(s, md, secret, ivlabel, sizeof(ivlabel) - 1,
100 NULL, iv, ivlen);
101 }
102
103 int tls13_derive_finishedkey(SSL *s, const EVP_MD *md,
104 const unsigned char *secret,
105 unsigned char *fin, size_t finlen)
106 {
107 static const unsigned char finishedlabel[] = "finished";
108
109 return tls13_hkdf_expand(s, md, secret, finishedlabel,
110 sizeof(finishedlabel) - 1, NULL, fin, finlen);
111 }
112
113 /*
114 * Given the previous secret |prevsecret| and a new input secret |insecret| of
115 * length |insecretlen|, generate a new secret and store it in the location
116 * pointed to by |outsecret|. Returns 1 on success 0 on failure.
117 */
118 int tls13_generate_secret(SSL *s, const EVP_MD *md,
119 const unsigned char *prevsecret,
120 const unsigned char *insecret,
121 size_t insecretlen,
122 unsigned char *outsecret)
123 {
124 size_t mdlen, prevsecretlen;
125 int ret;
126 EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
127
128 if (pctx == NULL)
129 return 0;
130
131 mdlen = EVP_MD_size(md);
132
133 if (insecret == NULL) {
134 insecret = default_zeros;
135 insecretlen = mdlen;
136 }
137 if (prevsecret == NULL) {
138 prevsecret = default_zeros;
139 prevsecretlen = 0;
140 } else {
141 prevsecretlen = mdlen;
142 }
143
144 ret = EVP_PKEY_derive_init(pctx) <= 0
145 || EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY)
146 <= 0
147 || EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
148 || EVP_PKEY_CTX_set1_hkdf_key(pctx, insecret, insecretlen) <= 0
149 || EVP_PKEY_CTX_set1_hkdf_salt(pctx, prevsecret, prevsecretlen)
150 <= 0
151 || EVP_PKEY_derive(pctx, outsecret, &mdlen)
152 <= 0;
153
154 EVP_PKEY_CTX_free(pctx);
155 return ret == 0;
156 }
157
158 /*
159 * Given an input secret |insecret| of length |insecretlen| generate the
160 * handshake secret. This requires the early secret to already have been
161 * generated. Returns 1 on success 0 on failure.
162 */
163 int tls13_generate_handshake_secret(SSL *s, const unsigned char *insecret,
164 size_t insecretlen)
165 {
166 return tls13_generate_secret(s, ssl_handshake_md(s), s->early_secret,
167 insecret, insecretlen,
168 (unsigned char *)&s->handshake_secret);
169 }
170
171 /*
172 * Given the handshake secret |prev| of length |prevlen| generate the master
173 * secret and store its length in |*secret_size|. Returns 1 on success 0 on
174 * failure.
175 */
176 int tls13_generate_master_secret(SSL *s, unsigned char *out,
177 unsigned char *prev, size_t prevlen,
178 size_t *secret_size)
179 {
180 const EVP_MD *md = ssl_handshake_md(s);
181
182 *secret_size = EVP_MD_size(md);
183 return tls13_generate_secret(s, md, prev, NULL, 0, out);
184 }
185
186 /*
187 * Generates the mac for the Finished message. Returns the length of the MAC or
188 * 0 on error.
189 */
190 size_t tls13_final_finish_mac(SSL *s, const char *str, size_t slen,
191 unsigned char *out)
192 {
193 const EVP_MD *md = ssl_handshake_md(s);
194 unsigned char hash[EVP_MAX_MD_SIZE];
195 size_t hashlen, ret = 0;
196 EVP_PKEY *key = NULL;
197 EVP_MD_CTX *ctx = EVP_MD_CTX_new();
198
199 if (!ssl_handshake_hash(s, hash, sizeof(hash), &hashlen))
200 goto err;
201
202 if (str == s->method->ssl3_enc->server_finished_label)
203 key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
204 s->server_finished_secret, hashlen);
205 else
206 key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
207 s->client_finished_secret, hashlen);
208
209 if (key == NULL
210 || ctx == NULL
211 || EVP_DigestSignInit(ctx, NULL, md, NULL, key) <= 0
212 || EVP_DigestSignUpdate(ctx, hash, hashlen) <= 0
213 || EVP_DigestSignFinal(ctx, out, &hashlen) <= 0)
214 goto err;
215
216 ret = hashlen;
217 err:
218 EVP_PKEY_free(key);
219 EVP_MD_CTX_free(ctx);
220 return ret;
221 }
222
223 /*
224 * There isn't really a key block in TLSv1.3, but we still need this function
225 * for initialising the cipher and hash. Returns 1 on success or 0 on failure.
226 */
227 int tls13_setup_key_block(SSL *s)
228 {
229 const EVP_CIPHER *c;
230 const EVP_MD *hash;
231 int mac_type = NID_undef;
232
233 s->session->cipher = s->s3->tmp.new_cipher;
234 if (!ssl_cipher_get_evp
235 (s->session, &c, &hash, &mac_type, NULL, NULL, 0)) {
236 SSLerr(SSL_F_TLS13_SETUP_KEY_BLOCK, SSL_R_CIPHER_OR_HASH_UNAVAILABLE);
237 return 0;
238 }
239
240 s->s3->tmp.new_sym_enc = c;
241 s->s3->tmp.new_hash = hash;
242
243 return 1;
244 }
245
246 static int derive_secret_key_and_iv(SSL *s, int send, const EVP_MD *md,
247 const EVP_CIPHER *ciph,
248 const unsigned char *insecret,
249 const unsigned char *hash,
250 const unsigned char *label,
251 size_t labellen, unsigned char *secret,
252 unsigned char *iv, EVP_CIPHER_CTX *ciph_ctx)
253 {
254 unsigned char key[EVP_MAX_KEY_LENGTH];
255 size_t ivlen, keylen, taglen;
256 size_t hashlen = EVP_MD_size(md);
257
258 if (!tls13_hkdf_expand(s, md, insecret, label, labellen, hash, secret,
259 hashlen)) {
260 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_INTERNAL_ERROR);
261 goto err;
262 }
263
264 /* TODO(size_t): convert me */
265 keylen = EVP_CIPHER_key_length(ciph);
266 if (EVP_CIPHER_mode(ciph) == EVP_CIPH_CCM_MODE) {
267 ivlen = EVP_CCM_TLS_IV_LEN;
268 if (s->s3->tmp.new_cipher->algorithm_enc
269 & (SSL_AES128CCM8 | SSL_AES256CCM8))
270 taglen = EVP_CCM8_TLS_TAG_LEN;
271 else
272 taglen = EVP_CCM_TLS_TAG_LEN;
273 } else {
274 ivlen = EVP_CIPHER_iv_length(ciph);
275 taglen = 0;
276 }
277
278 if (!tls13_derive_key(s, md, secret, key, keylen)
279 || !tls13_derive_iv(s, md, secret, iv, ivlen)) {
280 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_INTERNAL_ERROR);
281 goto err;
282 }
283
284 if (EVP_CipherInit_ex(ciph_ctx, ciph, NULL, NULL, NULL, send) <= 0
285 || !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
286 || (taglen != 0 && !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_TAG,
287 taglen, NULL))
288 || EVP_CipherInit_ex(ciph_ctx, NULL, NULL, key, NULL, -1) <= 0) {
289 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_EVP_LIB);
290 goto err;
291 }
292
293 #ifdef OPENSSL_SSL_TRACE_CRYPTO
294 if (s->msg_callback) {
295 int wh = send ? TLS1_RT_CRYPTO_WRITE : 0;
296
297 if (ciph->key_len)
298 s->msg_callback(2, s->version, wh | TLS1_RT_CRYPTO_KEY,
299 key, ciph->key_len, s, s->msg_callback_arg);
300
301 wh |= TLS1_RT_CRYPTO_IV;
302 s->msg_callback(2, s->version, wh, iv, ivlen, s,
303 s->msg_callback_arg);
304 }
305 #endif
306
307 return 1;
308 err:
309 OPENSSL_cleanse(key, sizeof(key));
310 return 0;
311 }
312
313 int tls13_change_cipher_state(SSL *s, int which)
314 {
315 static const unsigned char client_early_traffic[] =
316 "client early traffic secret";
317 static const unsigned char client_handshake_traffic[] =
318 "client handshake traffic secret";
319 static const unsigned char client_application_traffic[] =
320 "client application traffic secret";
321 static const unsigned char server_handshake_traffic[] =
322 "server handshake traffic secret";
323 static const unsigned char server_application_traffic[] =
324 "server application traffic secret";
325 static const unsigned char resumption_master_secret[] =
326 "resumption master secret";
327 unsigned char *iv;
328 unsigned char secret[EVP_MAX_MD_SIZE];
329 unsigned char hashval[EVP_MAX_MD_SIZE];
330 unsigned char *hash = hashval;
331 unsigned char *insecret;
332 unsigned char *finsecret = NULL;
333 const char *log_label = NULL;
334 EVP_CIPHER_CTX *ciph_ctx;
335 size_t finsecretlen = 0;
336 const unsigned char *label;
337 size_t labellen, hashlen = 0;
338 int ret = 0;
339 const EVP_MD *md;
340 const EVP_CIPHER *cipher;
341
342 if (which & SSL3_CC_READ) {
343 if (s->enc_read_ctx != NULL) {
344 EVP_CIPHER_CTX_reset(s->enc_read_ctx);
345 } else {
346 s->enc_read_ctx = EVP_CIPHER_CTX_new();
347 if (s->enc_read_ctx == NULL) {
348 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
349 goto err;
350 }
351 }
352 ciph_ctx = s->enc_read_ctx;
353 iv = s->read_iv;
354
355 RECORD_LAYER_reset_read_sequence(&s->rlayer);
356 } else {
357 if (s->enc_write_ctx != NULL) {
358 EVP_CIPHER_CTX_reset(s->enc_write_ctx);
359 } else {
360 s->enc_write_ctx = EVP_CIPHER_CTX_new();
361 if (s->enc_write_ctx == NULL) {
362 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
363 goto err;
364 }
365 }
366 ciph_ctx = s->enc_write_ctx;
367 iv = s->write_iv;
368
369 RECORD_LAYER_reset_write_sequence(&s->rlayer);
370 }
371
372 if (((which & SSL3_CC_CLIENT) && (which & SSL3_CC_WRITE))
373 || ((which & SSL3_CC_SERVER) && (which & SSL3_CC_READ))) {
374 if (which & SSL3_CC_EARLY) {
375 EVP_MD_CTX *mdctx = NULL;
376 long handlen;
377 void *hdata;
378 unsigned int hashlenui;
379 const SSL_CIPHER *sslcipher = SSL_SESSION_get0_cipher(s->session);
380
381 insecret = s->early_secret;
382 label = client_early_traffic;
383 labellen = sizeof(client_early_traffic) - 1;
384 log_label = CLIENT_EARLY_LABEL;
385
386 handlen = BIO_get_mem_data(s->s3->handshake_buffer, &hdata);
387 if (handlen <= 0) {
388 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE,
389 SSL_R_BAD_HANDSHAKE_LENGTH);
390 goto err;
391 }
392 if (sslcipher == NULL) {
393 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
394 goto err;
395 }
396
397 /*
398 * We need to calculate the handshake digest using the digest from
399 * the session. We haven't yet selected our ciphersuite so we can't
400 * use ssl_handshake_md().
401 */
402 mdctx = EVP_MD_CTX_new();
403 if (mdctx == NULL) {
404 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
405 goto err;
406 }
407 cipher = EVP_get_cipherbynid(SSL_CIPHER_get_cipher_nid(sslcipher));
408 md = ssl_md(sslcipher->algorithm2);
409 if (md == NULL || !EVP_DigestInit_ex(mdctx, md, NULL)
410 || !EVP_DigestUpdate(mdctx, hdata, handlen)
411 || !EVP_DigestFinal_ex(mdctx, hashval, &hashlenui)) {
412 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
413 EVP_MD_CTX_free(mdctx);
414 goto err;
415 }
416 hashlen = hashlenui;
417 EVP_MD_CTX_free(mdctx);
418 } else if (which & SSL3_CC_HANDSHAKE) {
419 insecret = s->handshake_secret;
420 finsecret = s->client_finished_secret;
421 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
422 label = client_handshake_traffic;
423 labellen = sizeof(client_handshake_traffic) - 1;
424 log_label = CLIENT_HANDSHAKE_LABEL;
425 /*
426 * The hanshake hash used for the server read handshake traffic
427 * secret is the same as the hash for the server write handshake
428 * traffic secret. However, if we processed early data then we delay
429 * changing the server read cipher state until later, and the
430 * handshake hashes have moved on. Therefore we use the value saved
431 * earlier when we did the server write change cipher state.
432 */
433 if (s->server)
434 hash = s->handshake_traffic_hash;
435 } else {
436 insecret = s->master_secret;
437 label = client_application_traffic;
438 labellen = sizeof(client_application_traffic) - 1;
439 log_label = CLIENT_APPLICATION_LABEL;
440 /*
441 * For this we only use the handshake hashes up until the server
442 * Finished hash. We do not include the client's Finished, which is
443 * what ssl_handshake_hash() would give us. Instead we use the
444 * previously saved value.
445 */
446 hash = s->server_finished_hash;
447 }
448 } else {
449 /* Early data never applies to client-read/server-write */
450 if (which & SSL3_CC_HANDSHAKE) {
451 insecret = s->handshake_secret;
452 finsecret = s->server_finished_secret;
453 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
454 label = server_handshake_traffic;
455 labellen = sizeof(server_handshake_traffic) - 1;
456 log_label = SERVER_HANDSHAKE_LABEL;
457 } else {
458 insecret = s->master_secret;
459 label = server_application_traffic;
460 labellen = sizeof(server_application_traffic) - 1;
461 log_label = SERVER_APPLICATION_LABEL;
462 }
463 }
464
465 if (!(which & SSL3_CC_EARLY)) {
466 md = ssl_handshake_md(s);
467 cipher = s->s3->tmp.new_sym_enc;
468 if (!ssl3_digest_cached_records(s, 1)
469 || !ssl_handshake_hash(s, hashval, sizeof(hashval), &hashlen)) {
470 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
471 goto err;
472 }
473 }
474
475 /*
476 * Save the hash of handshakes up to now for use when we calculate the
477 * client application traffic secret
478 */
479 if (label == server_application_traffic)
480 memcpy(s->server_finished_hash, hashval, hashlen);
481
482 if (s->server && label == server_handshake_traffic)
483 memcpy(s->handshake_traffic_hash, hashval, hashlen);
484
485 if (label == client_application_traffic) {
486 /*
487 * We also create the resumption master secret, but this time use the
488 * hash for the whole handshake including the Client Finished
489 */
490 if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret,
491 resumption_master_secret,
492 sizeof(resumption_master_secret) - 1,
493 hashval, s->session->master_key, hashlen)) {
494 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
495 goto err;
496 }
497 s->session->master_key_length = hashlen;
498 }
499
500 if (!derive_secret_key_and_iv(s, which & SSL3_CC_WRITE, md, cipher,
501 insecret, hash, label, labellen, secret, iv,
502 ciph_ctx)) {
503 goto err;
504 }
505
506 if (label == server_application_traffic)
507 memcpy(s->server_app_traffic_secret, secret, hashlen);
508 else if (label == client_application_traffic)
509 memcpy(s->client_app_traffic_secret, secret, hashlen);
510
511 if (!ssl_log_secret(s, log_label, secret, hashlen)) {
512 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
513 goto err;
514 }
515
516 if (finsecret != NULL
517 && !tls13_derive_finishedkey(s, ssl_handshake_md(s), secret,
518 finsecret, finsecretlen)) {
519 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
520 goto err;
521 }
522
523 ret = 1;
524 err:
525 OPENSSL_cleanse(secret, sizeof(secret));
526 return ret;
527 }
528
529 int tls13_update_key(SSL *s, int send)
530 {
531 static const unsigned char application_traffic[] =
532 "application traffic secret";
533 const EVP_MD *md = ssl_handshake_md(s);
534 size_t hashlen = EVP_MD_size(md);
535 unsigned char *insecret, *iv;
536 unsigned char secret[EVP_MAX_MD_SIZE];
537 EVP_CIPHER_CTX *ciph_ctx;
538 int ret = 0;
539
540 if (s->server == send)
541 insecret = s->server_app_traffic_secret;
542 else
543 insecret = s->client_app_traffic_secret;
544
545 if (send) {
546 iv = s->write_iv;
547 ciph_ctx = s->enc_write_ctx;
548 RECORD_LAYER_reset_write_sequence(&s->rlayer);
549 } else {
550 iv = s->read_iv;
551 ciph_ctx = s->enc_read_ctx;
552 RECORD_LAYER_reset_read_sequence(&s->rlayer);
553 }
554
555 if (!derive_secret_key_and_iv(s, send, ssl_handshake_md(s),
556 s->s3->tmp.new_sym_enc, insecret, NULL,
557 application_traffic,
558 sizeof(application_traffic) - 1, secret, iv,
559 ciph_ctx))
560 goto err;
561
562 memcpy(insecret, secret, hashlen);
563
564 ret = 1;
565 err:
566 OPENSSL_cleanse(secret, sizeof(secret));
567 return ret;
568 }
569
570 int tls13_alert_code(int code)
571 {
572 if (code == SSL_AD_MISSING_EXTENSION || code == SSL_AD_END_OF_EARLY_DATA)
573 return code;
574
575 return tls1_alert_code(code);
576 }