1 /*
2 * Copyright 2016-2022 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (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 /*
11 * Refer to "The TLS Protocol Version 1.0" Section 5
12 * (https://tools.ietf.org/html/rfc2246#section-5) and
13 * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
14 * (https://tools.ietf.org/html/rfc5246#section-5).
15 *
16 * For TLS v1.0 and TLS v1.1 the TLS PRF algorithm is given by:
17 *
18 * PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
19 * P_SHA-1(S2, label + seed)
20 *
21 * where P_MD5 and P_SHA-1 are defined by P_<hash>, below, and S1 and S2 are
22 * two halves of the secret (with the possibility of one shared byte, in the
23 * case where the length of the original secret is odd). S1 is taken from the
24 * first half of the secret, S2 from the second half.
25 *
26 * For TLS v1.2 the TLS PRF algorithm is given by:
27 *
28 * PRF(secret, label, seed) = P_<hash>(secret, label + seed)
29 *
30 * where hash is SHA-256 for all cipher suites defined in RFC 5246 as well as
31 * those published prior to TLS v1.2 while the TLS v1.2 protocol is in effect,
32 * unless defined otherwise by the cipher suite.
33 *
34 * P_<hash> is an expansion function that uses a single hash function to expand
35 * a secret and seed into an arbitrary quantity of output:
36 *
37 * P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
38 * HMAC_<hash>(secret, A(2) + seed) +
39 * HMAC_<hash>(secret, A(3) + seed) + ...
40 *
41 * where + indicates concatenation. P_<hash> can be iterated as many times as
42 * is necessary to produce the required quantity of data.
43 *
44 * A(i) is defined as:
45 * A(0) = seed
46 * A(i) = HMAC_<hash>(secret, A(i-1))
47 */
48 #include <stdio.h>
49 #include <stdarg.h>
50 #include <string.h>
51 #include <openssl/evp.h>
52 #include <openssl/kdf.h>
53 #include <openssl/core_names.h>
54 #include <openssl/params.h>
55 #include <openssl/proverr.h>
56 #include "internal/cryptlib.h"
57 #include "internal/numbers.h"
58 #include "crypto/evp.h"
59 #include "prov/provider_ctx.h"
60 #include "prov/providercommon.h"
61 #include "prov/implementations.h"
62 #include "prov/provider_util.h"
63 #include "internal/e_os.h"
64
65 static OSSL_FUNC_kdf_newctx_fn kdf_tls1_prf_new;
66 static OSSL_FUNC_kdf_dupctx_fn kdf_tls1_prf_dup;
67 static OSSL_FUNC_kdf_freectx_fn kdf_tls1_prf_free;
68 static OSSL_FUNC_kdf_reset_fn kdf_tls1_prf_reset;
69 static OSSL_FUNC_kdf_derive_fn kdf_tls1_prf_derive;
70 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_tls1_prf_settable_ctx_params;
71 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_tls1_prf_set_ctx_params;
72 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_tls1_prf_gettable_ctx_params;
73 static OSSL_FUNC_kdf_get_ctx_params_fn kdf_tls1_prf_get_ctx_params;
74
75 static int tls1_prf_alg(EVP_MAC_CTX *mdctx, EVP_MAC_CTX *sha1ctx,
76 const unsigned char *sec, size_t slen,
77 const unsigned char *seed, size_t seed_len,
78 unsigned char *out, size_t olen);
79
80 #define TLS1_PRF_MAXBUF 1024
81
82 /* TLS KDF kdf context structure */
83 typedef struct {
84 void *provctx;
85
86 /* MAC context for the main digest */
87 EVP_MAC_CTX *P_hash;
88 /* MAC context for SHA1 for the MD5/SHA-1 combined PRF */
89 EVP_MAC_CTX *P_sha1;
90
91 /* Secret value to use for PRF */
92 unsigned char *sec;
93 size_t seclen;
94 /* Buffer of concatenated seed data */
95 unsigned char seed[TLS1_PRF_MAXBUF];
96 size_t seedlen;
97 } TLS1_PRF;
98
kdf_tls1_prf_new(void * provctx)99 static void *kdf_tls1_prf_new(void *provctx)
100 {
101 TLS1_PRF *ctx;
102
103 if (!ossl_prov_is_running())
104 return NULL;
105
106 if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL) {
107 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
108 return NULL;
109 }
110 ctx->provctx = provctx;
111 return ctx;
112 }
113
kdf_tls1_prf_free(void * vctx)114 static void kdf_tls1_prf_free(void *vctx)
115 {
116 TLS1_PRF *ctx = (TLS1_PRF *)vctx;
117
118 if (ctx != NULL) {
119 kdf_tls1_prf_reset(ctx);
120 OPENSSL_free(ctx);
121 }
122 }
123
kdf_tls1_prf_reset(void * vctx)124 static void kdf_tls1_prf_reset(void *vctx)
125 {
126 TLS1_PRF *ctx = (TLS1_PRF *)vctx;
127 void *provctx = ctx->provctx;
128
129 EVP_MAC_CTX_free(ctx->P_hash);
130 EVP_MAC_CTX_free(ctx->P_sha1);
131 OPENSSL_clear_free(ctx->sec, ctx->seclen);
132 OPENSSL_cleanse(ctx->seed, ctx->seedlen);
133 memset(ctx, 0, sizeof(*ctx));
134 ctx->provctx = provctx;
135 }
136
kdf_tls1_prf_dup(void * vctx)137 static void *kdf_tls1_prf_dup(void *vctx)
138 {
139 const TLS1_PRF *src = (const TLS1_PRF *)vctx;
140 TLS1_PRF *dest;
141
142 dest = kdf_tls1_prf_new(src->provctx);
143 if (dest != NULL) {
144 if (src->P_hash != NULL
145 && (dest->P_hash = EVP_MAC_CTX_dup(src->P_hash)) == NULL)
146 goto err;
147 if (src->P_sha1 != NULL
148 && (dest->P_sha1 = EVP_MAC_CTX_dup(src->P_sha1)) == NULL)
149 goto err;
150 if (!ossl_prov_memdup(src->sec, src->seclen, &dest->sec, &dest->seclen))
151 goto err;
152 memcpy(dest->seed, src->seed, src->seedlen);
153 dest->seedlen = src->seedlen;
154 }
155 return dest;
156
157 err:
158 kdf_tls1_prf_free(dest);
159 return NULL;
160 }
161
kdf_tls1_prf_derive(void * vctx,unsigned char * key,size_t keylen,const OSSL_PARAM params[])162 static int kdf_tls1_prf_derive(void *vctx, unsigned char *key, size_t keylen,
163 const OSSL_PARAM params[])
164 {
165 TLS1_PRF *ctx = (TLS1_PRF *)vctx;
166
167 if (!ossl_prov_is_running() || !kdf_tls1_prf_set_ctx_params(ctx, params))
168 return 0;
169
170 if (ctx->P_hash == NULL) {
171 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
172 return 0;
173 }
174 if (ctx->sec == NULL) {
175 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
176 return 0;
177 }
178 if (ctx->seedlen == 0) {
179 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SEED);
180 return 0;
181 }
182 if (keylen == 0) {
183 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
184 return 0;
185 }
186
187 return tls1_prf_alg(ctx->P_hash, ctx->P_sha1,
188 ctx->sec, ctx->seclen,
189 ctx->seed, ctx->seedlen,
190 key, keylen);
191 }
192
kdf_tls1_prf_set_ctx_params(void * vctx,const OSSL_PARAM params[])193 static int kdf_tls1_prf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
194 {
195 const OSSL_PARAM *p;
196 TLS1_PRF *ctx = vctx;
197 OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
198
199 if (params == NULL)
200 return 1;
201
202 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL) {
203 if (OPENSSL_strcasecmp(p->data, SN_md5_sha1) == 0) {
204 if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
205 OSSL_MAC_NAME_HMAC,
206 NULL, SN_md5, libctx)
207 || !ossl_prov_macctx_load_from_params(&ctx->P_sha1, params,
208 OSSL_MAC_NAME_HMAC,
209 NULL, SN_sha1, libctx))
210 return 0;
211 } else {
212 EVP_MAC_CTX_free(ctx->P_sha1);
213 if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
214 OSSL_MAC_NAME_HMAC,
215 NULL, NULL, libctx))
216 return 0;
217 }
218 }
219
220 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL) {
221 OPENSSL_clear_free(ctx->sec, ctx->seclen);
222 ctx->sec = NULL;
223 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->sec, 0, &ctx->seclen))
224 return 0;
225 }
226 /* The seed fields concatenate, so process them all */
227 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED)) != NULL) {
228 for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
229 OSSL_KDF_PARAM_SEED)) {
230 const void *q = ctx->seed + ctx->seedlen;
231 size_t sz = 0;
232
233 if (p->data_size != 0
234 && p->data != NULL
235 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
236 TLS1_PRF_MAXBUF - ctx->seedlen,
237 &sz))
238 return 0;
239 ctx->seedlen += sz;
240 }
241 }
242 return 1;
243 }
244
kdf_tls1_prf_settable_ctx_params(ossl_unused void * ctx,ossl_unused void * provctx)245 static const OSSL_PARAM *kdf_tls1_prf_settable_ctx_params(
246 ossl_unused void *ctx, ossl_unused void *provctx)
247 {
248 static const OSSL_PARAM known_settable_ctx_params[] = {
249 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
250 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
251 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
252 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
253 OSSL_PARAM_END
254 };
255 return known_settable_ctx_params;
256 }
257
kdf_tls1_prf_get_ctx_params(void * vctx,OSSL_PARAM params[])258 static int kdf_tls1_prf_get_ctx_params(void *vctx, OSSL_PARAM params[])
259 {
260 OSSL_PARAM *p;
261
262 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
263 return OSSL_PARAM_set_size_t(p, SIZE_MAX);
264 return -2;
265 }
266
kdf_tls1_prf_gettable_ctx_params(ossl_unused void * ctx,ossl_unused void * provctx)267 static const OSSL_PARAM *kdf_tls1_prf_gettable_ctx_params(
268 ossl_unused void *ctx, ossl_unused void *provctx)
269 {
270 static const OSSL_PARAM known_gettable_ctx_params[] = {
271 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
272 OSSL_PARAM_END
273 };
274 return known_gettable_ctx_params;
275 }
276
277 const OSSL_DISPATCH ossl_kdf_tls1_prf_functions[] = {
278 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_tls1_prf_new },
279 { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_tls1_prf_dup },
280 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_tls1_prf_free },
281 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_tls1_prf_reset },
282 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_tls1_prf_derive },
283 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
284 (void(*)(void))kdf_tls1_prf_settable_ctx_params },
285 { OSSL_FUNC_KDF_SET_CTX_PARAMS,
286 (void(*)(void))kdf_tls1_prf_set_ctx_params },
287 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
288 (void(*)(void))kdf_tls1_prf_gettable_ctx_params },
289 { OSSL_FUNC_KDF_GET_CTX_PARAMS,
290 (void(*)(void))kdf_tls1_prf_get_ctx_params },
291 { 0, NULL }
292 };
293
294 /*
295 * Refer to "The TLS Protocol Version 1.0" Section 5
296 * (https://tools.ietf.org/html/rfc2246#section-5) and
297 * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
298 * (https://tools.ietf.org/html/rfc5246#section-5).
299 *
300 * P_<hash> is an expansion function that uses a single hash function to expand
301 * a secret and seed into an arbitrary quantity of output:
302 *
303 * P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
304 * HMAC_<hash>(secret, A(2) + seed) +
305 * HMAC_<hash>(secret, A(3) + seed) + ...
306 *
307 * where + indicates concatenation. P_<hash> can be iterated as many times as
308 * is necessary to produce the required quantity of data.
309 *
310 * A(i) is defined as:
311 * A(0) = seed
312 * A(i) = HMAC_<hash>(secret, A(i-1))
313 */
tls1_prf_P_hash(EVP_MAC_CTX * ctx_init,const unsigned char * sec,size_t sec_len,const unsigned char * seed,size_t seed_len,unsigned char * out,size_t olen)314 static int tls1_prf_P_hash(EVP_MAC_CTX *ctx_init,
315 const unsigned char *sec, size_t sec_len,
316 const unsigned char *seed, size_t seed_len,
317 unsigned char *out, size_t olen)
318 {
319 size_t chunk;
320 EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL;
321 unsigned char Ai[EVP_MAX_MD_SIZE];
322 size_t Ai_len;
323 int ret = 0;
324
325 if (!EVP_MAC_init(ctx_init, sec, sec_len, NULL))
326 goto err;
327 chunk = EVP_MAC_CTX_get_mac_size(ctx_init);
328 if (chunk == 0)
329 goto err;
330 /* A(0) = seed */
331 ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
332 if (ctx_Ai == NULL)
333 goto err;
334 if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
335 goto err;
336
337 for (;;) {
338 /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
339 if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len, sizeof(Ai)))
340 goto err;
341 EVP_MAC_CTX_free(ctx_Ai);
342 ctx_Ai = NULL;
343
344 /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
345 ctx = EVP_MAC_CTX_dup(ctx_init);
346 if (ctx == NULL)
347 goto err;
348 if (!EVP_MAC_update(ctx, Ai, Ai_len))
349 goto err;
350 /* save state for calculating next A(i) value */
351 if (olen > chunk) {
352 ctx_Ai = EVP_MAC_CTX_dup(ctx);
353 if (ctx_Ai == NULL)
354 goto err;
355 }
356 if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
357 goto err;
358 if (olen <= chunk) {
359 /* last chunk - use Ai as temp bounce buffer */
360 if (!EVP_MAC_final(ctx, Ai, &Ai_len, sizeof(Ai)))
361 goto err;
362 memcpy(out, Ai, olen);
363 break;
364 }
365 if (!EVP_MAC_final(ctx, out, NULL, olen))
366 goto err;
367 EVP_MAC_CTX_free(ctx);
368 ctx = NULL;
369 out += chunk;
370 olen -= chunk;
371 }
372 ret = 1;
373 err:
374 EVP_MAC_CTX_free(ctx);
375 EVP_MAC_CTX_free(ctx_Ai);
376 OPENSSL_cleanse(Ai, sizeof(Ai));
377 return ret;
378 }
379
380 /*
381 * Refer to "The TLS Protocol Version 1.0" Section 5
382 * (https://tools.ietf.org/html/rfc2246#section-5) and
383 * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
384 * (https://tools.ietf.org/html/rfc5246#section-5).
385 *
386 * For TLS v1.0 and TLS v1.1:
387 *
388 * PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
389 * P_SHA-1(S2, label + seed)
390 *
391 * S1 is taken from the first half of the secret, S2 from the second half.
392 *
393 * L_S = length in bytes of secret;
394 * L_S1 = L_S2 = ceil(L_S / 2);
395 *
396 * For TLS v1.2:
397 *
398 * PRF(secret, label, seed) = P_<hash>(secret, label + seed)
399 */
tls1_prf_alg(EVP_MAC_CTX * mdctx,EVP_MAC_CTX * sha1ctx,const unsigned char * sec,size_t slen,const unsigned char * seed,size_t seed_len,unsigned char * out,size_t olen)400 static int tls1_prf_alg(EVP_MAC_CTX *mdctx, EVP_MAC_CTX *sha1ctx,
401 const unsigned char *sec, size_t slen,
402 const unsigned char *seed, size_t seed_len,
403 unsigned char *out, size_t olen)
404 {
405 if (sha1ctx != NULL) {
406 /* TLS v1.0 and TLS v1.1 */
407 size_t i;
408 unsigned char *tmp;
409 /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
410 size_t L_S1 = (slen + 1) / 2;
411 size_t L_S2 = L_S1;
412
413 if (!tls1_prf_P_hash(mdctx, sec, L_S1,
414 seed, seed_len, out, olen))
415 return 0;
416
417 if ((tmp = OPENSSL_malloc(olen)) == NULL) {
418 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
419 return 0;
420 }
421
422 if (!tls1_prf_P_hash(sha1ctx, sec + slen - L_S2, L_S2,
423 seed, seed_len, tmp, olen)) {
424 OPENSSL_clear_free(tmp, olen);
425 return 0;
426 }
427 for (i = 0; i < olen; i++)
428 out[i] ^= tmp[i];
429 OPENSSL_clear_free(tmp, olen);
430 return 1;
431 }
432
433 /* TLS v1.2 */
434 if (!tls1_prf_P_hash(mdctx, sec, slen, seed, seed_len, out, olen))
435 return 0;
436
437 return 1;
438 }
439