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