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 
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 
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 
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 
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 
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 
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 
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 
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  */
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  */
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