providers/implementations/kdfs/tls1_prf.c

   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
  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     ctx->provctx = provctx;
 109     return ctx;
 110 }
 111
 112 static void kdf_tls1_prf_free(void *vctx)
 113 {
 114     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 115
 116     if (ctx != NULL) {
 117         kdf_tls1_prf_reset(ctx);
 118         OPENSSL_free(ctx);
 119     }
 120 }
 121
 122 static void kdf_tls1_prf_reset(void *vctx)
 123 {
 124     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 125     void *provctx = ctx->provctx;
 126
 127     EVP_MAC_CTX_free(ctx->P_hash);
 128     EVP_MAC_CTX_free(ctx->P_sha1);
 129     OPENSSL_clear_free(ctx->sec, ctx->seclen);
 130     OPENSSL_cleanse(ctx->seed, ctx->seedlen);
 131     memset(ctx, 0, sizeof(*ctx));
 132     ctx->provctx = provctx;
 133 }
 134
 135 static void *kdf_tls1_prf_dup(void *vctx)
 136 {
 137     const TLS1_PRF *src = (const TLS1_PRF *)vctx;
 138     TLS1_PRF *dest;
 139
 140     dest = kdf_tls1_prf_new(src->provctx);
 141     if (dest != NULL) {
 142         if (src->P_hash != NULL
 143                     && (dest->P_hash = EVP_MAC_CTX_dup(src->P_hash)) == NULL)
 144             goto err;
 145         if (src->P_sha1 != NULL
 146                     && (dest->P_sha1 = EVP_MAC_CTX_dup(src->P_sha1)) == NULL)
 147             goto err;
 148         if (!ossl_prov_memdup(src->sec, src->seclen, &dest->sec, &dest->seclen))
 149             goto err;
 150         memcpy(dest->seed, src->seed, src->seedlen);
 151         dest->seedlen = src->seedlen;
 152     }
 153     return dest;
 154
 155  err:
 156     kdf_tls1_prf_free(dest);
 157     return NULL;
 158 }
 159
 160 static int kdf_tls1_prf_derive(void *vctx, unsigned char *key, size_t keylen,
 161                                const OSSL_PARAM params[])
 162 {
 163     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 164
 165     if (!ossl_prov_is_running() || !kdf_tls1_prf_set_ctx_params(ctx, params))
 166         return 0;
 167
 168     if (ctx->P_hash == NULL) {
 169         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 170         return 0;
 171     }
 172     if (ctx->sec == NULL) {
 173         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 174         return 0;
 175     }
 176     if (ctx->seedlen == 0) {
 177         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SEED);
 178         return 0;
 179     }
 180     if (keylen == 0) {
 181         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
 182         return 0;
 183     }
 184
 185     return tls1_prf_alg(ctx->P_hash, ctx->P_sha1,
 186                         ctx->sec, ctx->seclen,
 187                         ctx->seed, ctx->seedlen,
 188                         key, keylen);
 189 }
 190
 191 static int kdf_tls1_prf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 192 {
 193     const OSSL_PARAM *p;
 194     TLS1_PRF *ctx = vctx;
 195     OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
 196
 197     if (params == NULL)
 198         return 1;
 199
 200     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL) {
 201         if (OPENSSL_strcasecmp(p->data, SN_md5_sha1) == 0) {
 202             if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
 203                                                    OSSL_MAC_NAME_HMAC,
 204                                                    NULL, SN_md5, libctx)
 205                 || !ossl_prov_macctx_load_from_params(&ctx->P_sha1, params,
 206                                                       OSSL_MAC_NAME_HMAC,
 207                                                       NULL, SN_sha1, libctx))
 208                 return 0;
 209         } else {
 210             EVP_MAC_CTX_free(ctx->P_sha1);
 211             if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
 212                                                    OSSL_MAC_NAME_HMAC,
 213                                                    NULL, NULL, libctx))
 214                 return 0;
 215         }
 216     }
 217
 218     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL) {
 219         OPENSSL_clear_free(ctx->sec, ctx->seclen);
 220         ctx->sec = NULL;
 221         if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->sec, 0, &ctx->seclen))
 222             return 0;
 223     }
 224     /* The seed fields concatenate, so process them all */
 225     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED)) != NULL) {
 226         for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
 227                                                       OSSL_KDF_PARAM_SEED)) {
 228             const void *q = ctx->seed + ctx->seedlen;
 229             size_t sz = 0;
 230
 231             if (p->data_size != 0
 232                 && p->data != NULL
 233                 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
 234                                                 TLS1_PRF_MAXBUF - ctx->seedlen,
 235                                                 &sz))
 236                 return 0;
 237             ctx->seedlen += sz;
 238         }
 239     }
 240     return 1;
 241 }
 242
 243 static const OSSL_PARAM *kdf_tls1_prf_settable_ctx_params(
 244         ossl_unused void *ctx, ossl_unused void *provctx)
 245 {
 246     static const OSSL_PARAM known_settable_ctx_params[] = {
 247         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 248         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 249         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
 250         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
 251         OSSL_PARAM_END
 252     };
 253     return known_settable_ctx_params;
 254 }
 255
 256 static int kdf_tls1_prf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 257 {
 258     OSSL_PARAM *p;
 259
 260     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 261         return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 262     return -2;
 263 }
 264
 265 static const OSSL_PARAM *kdf_tls1_prf_gettable_ctx_params(
 266         ossl_unused void *ctx, ossl_unused void *provctx)
 267 {
 268     static const OSSL_PARAM known_gettable_ctx_params[] = {
 269         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 270         OSSL_PARAM_END
 271     };
 272     return known_gettable_ctx_params;
 273 }
 274
 275 const OSSL_DISPATCH ossl_kdf_tls1_prf_functions[] = {
 276     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_tls1_prf_new },
 277     { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_tls1_prf_dup },
 278     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_tls1_prf_free },
 279     { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_tls1_prf_reset },
 280     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_tls1_prf_derive },
 281     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 282       (void(*)(void))kdf_tls1_prf_settable_ctx_params },
 283     { OSSL_FUNC_KDF_SET_CTX_PARAMS,
 284       (void(*)(void))kdf_tls1_prf_set_ctx_params },
 285     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 286       (void(*)(void))kdf_tls1_prf_gettable_ctx_params },
 287     { OSSL_FUNC_KDF_GET_CTX_PARAMS,
 288       (void(*)(void))kdf_tls1_prf_get_ctx_params },
 289     { 0, NULL }
 290 };
 291
 292 /*
 293  * Refer to "The TLS Protocol Version 1.0" Section 5
 294  * (https://tools.ietf.org/html/rfc2246#section-5) and
 295  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
 296  * (https://tools.ietf.org/html/rfc5246#section-5).
 297  *
 298  * P_<hash> is an expansion function that uses a single hash function to expand
 299  * a secret and seed into an arbitrary quantity of output:
 300  *
 301  *   P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
 302  *                            HMAC_<hash>(secret, A(2) + seed) +
 303  *                            HMAC_<hash>(secret, A(3) + seed) + ...
 304  *
 305  * where + indicates concatenation.  P_<hash> can be iterated as many times as
 306  * is necessary to produce the required quantity of data.
 307  *
 308  * A(i) is defined as:
 309  *     A(0) = seed
 310  *     A(i) = HMAC_<hash>(secret, A(i-1))
 311  */
 312 static int tls1_prf_P_hash(EVP_MAC_CTX *ctx_init,
 313                            const unsigned char *sec, size_t sec_len,
 314                            const unsigned char *seed, size_t seed_len,
 315                            unsigned char *out, size_t olen)
 316 {
 317     size_t chunk;
 318     EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL;
 319     unsigned char Ai[EVP_MAX_MD_SIZE];
 320     size_t Ai_len;
 321     int ret = 0;
 322
 323     if (!EVP_MAC_init(ctx_init, sec, sec_len, NULL))
 324         goto err;
 325     chunk = EVP_MAC_CTX_get_mac_size(ctx_init);
 326     if (chunk == 0)
 327         goto err;
 328     /* A(0) = seed */
 329     ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
 330     if (ctx_Ai == NULL)
 331         goto err;
 332     if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
 333         goto err;
 334
 335     for (;;) {
 336         /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
 337         if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len, sizeof(Ai)))
 338             goto err;
 339         EVP_MAC_CTX_free(ctx_Ai);
 340         ctx_Ai = NULL;
 341
 342         /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
 343         ctx = EVP_MAC_CTX_dup(ctx_init);
 344         if (ctx == NULL)
 345             goto err;
 346         if (!EVP_MAC_update(ctx, Ai, Ai_len))
 347             goto err;
 348         /* save state for calculating next A(i) value */
 349         if (olen > chunk) {
 350             ctx_Ai = EVP_MAC_CTX_dup(ctx);
 351             if (ctx_Ai == NULL)
 352                 goto err;
 353         }
 354         if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
 355             goto err;
 356         if (olen <= chunk) {
 357             /* last chunk - use Ai as temp bounce buffer */
 358             if (!EVP_MAC_final(ctx, Ai, &Ai_len, sizeof(Ai)))
 359                 goto err;
 360             memcpy(out, Ai, olen);
 361             break;
 362         }
 363         if (!EVP_MAC_final(ctx, out, NULL, olen))
 364             goto err;
 365         EVP_MAC_CTX_free(ctx);
 366         ctx = NULL;
 367         out += chunk;
 368         olen -= chunk;
 369     }
 370     ret = 1;
 371  err:
 372     EVP_MAC_CTX_free(ctx);
 373     EVP_MAC_CTX_free(ctx_Ai);
 374     OPENSSL_cleanse(Ai, sizeof(Ai));
 375     return ret;
 376 }
 377
 378 /*
 379  * Refer to "The TLS Protocol Version 1.0" Section 5
 380  * (https://tools.ietf.org/html/rfc2246#section-5) and
 381  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
 382  * (https://tools.ietf.org/html/rfc5246#section-5).
 383  *
 384  * For TLS v1.0 and TLS v1.1:
 385  *
 386  *   PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
 387  *                              P_SHA-1(S2, label + seed)
 388  *
 389  * S1 is taken from the first half of the secret, S2 from the second half.
 390  *
 391  *   L_S = length in bytes of secret;
 392  *   L_S1 = L_S2 = ceil(L_S / 2);
 393  *
 394  * For TLS v1.2:
 395  *
 396  *   PRF(secret, label, seed) = P_<hash>(secret, label + seed)
 397  */
 398 static int tls1_prf_alg(EVP_MAC_CTX *mdctx, EVP_MAC_CTX *sha1ctx,
 399                         const unsigned char *sec, size_t slen,
 400                         const unsigned char *seed, size_t seed_len,
 401                         unsigned char *out, size_t olen)
 402 {
 403     if (sha1ctx != NULL) {
 404         /* TLS v1.0 and TLS v1.1 */
 405         size_t i;
 406         unsigned char *tmp;
 407         /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
 408         size_t L_S1 = (slen + 1) / 2;
 409         size_t L_S2 = L_S1;
 410
 411         if (!tls1_prf_P_hash(mdctx, sec, L_S1,
 412                              seed, seed_len, out, olen))
 413             return 0;
 414
 415         if ((tmp = OPENSSL_malloc(olen)) == NULL) {
 416             ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 417             return 0;
 418         }
 419
 420         if (!tls1_prf_P_hash(sha1ctx, sec + slen - L_S2, L_S2,
 421                              seed, seed_len, tmp, olen)) {
 422             OPENSSL_clear_free(tmp, olen);
 423             return 0;
 424         }
 425         for (i = 0; i < olen; i++)
 426             out[i] ^= tmp[i];
 427         OPENSSL_clear_free(tmp, olen);
 428         return 1;
 429     }
 430
 431     /* TLS v1.2 */
 432     if (!tls1_prf_P_hash(mdctx, sec, slen, seed, seed_len, out, olen))
 433         return 0;
 434
 435     return 1;
 436 }