providers/implementations/kdfs/tls1_prf.c

   1 /*
   2  * Copyright 2016-2023 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
  49 /*
  50  * Low level APIs (such as DH) are deprecated for public use, but still ok for
  51  * internal use.
  52  */
  53 #include "internal/deprecated.h"
  54
  55 #include <stdio.h>
  56 #include <stdarg.h>
  57 #include <string.h>
  58 #include <openssl/evp.h>
  59 #include <openssl/kdf.h>
  60 #include <openssl/core_names.h>
  61 #include <openssl/params.h>
  62 #include <openssl/proverr.h>
  63 #include "internal/cryptlib.h"
  64 #include "internal/numbers.h"
  65 #include "crypto/evp.h"
  66 #include "prov/provider_ctx.h"
  67 #include "prov/providercommon.h"
  68 #include "prov/implementations.h"
  69 #include "prov/provider_util.h"
  70 #include "prov/securitycheck.h"
  71 #include "internal/e_os.h"
  72
  73 static OSSL_FUNC_kdf_newctx_fn kdf_tls1_prf_new;
  74 static OSSL_FUNC_kdf_dupctx_fn kdf_tls1_prf_dup;
  75 static OSSL_FUNC_kdf_freectx_fn kdf_tls1_prf_free;
  76 static OSSL_FUNC_kdf_reset_fn kdf_tls1_prf_reset;
  77 static OSSL_FUNC_kdf_derive_fn kdf_tls1_prf_derive;
  78 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_tls1_prf_settable_ctx_params;
  79 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_tls1_prf_set_ctx_params;
  80 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_tls1_prf_gettable_ctx_params;
  81 static OSSL_FUNC_kdf_get_ctx_params_fn kdf_tls1_prf_get_ctx_params;
  82
  83 static int tls1_prf_alg(EVP_MAC_CTX *mdctx, EVP_MAC_CTX *sha1ctx,
  84                         const unsigned char *sec, size_t slen,
  85                         const unsigned char *seed, size_t seed_len,
  86                         unsigned char *out, size_t olen);
  87
  88 #define TLS1_PRF_MAXBUF 1024
  89 #define TLS_MD_MASTER_SECRET_CONST        "\x6d\x61\x73\x74\x65\x72\x20\x73\x65\x63\x72\x65\x74"
  90 #define TLS_MD_MASTER_SECRET_CONST_SIZE   13
  91
  92 /* TLS KDF kdf context structure */
  93 typedef struct {
  94     void *provctx;
  95
  96     /* MAC context for the main digest */
  97     EVP_MAC_CTX *P_hash;
  98     /* MAC context for SHA1 for the MD5/SHA-1 combined PRF */
  99     EVP_MAC_CTX *P_sha1;
 100
 101     /* Secret value to use for PRF */
 102     unsigned char *sec;
 103     size_t seclen;
 104     /* Buffer of concatenated seed data */
 105     unsigned char seed[TLS1_PRF_MAXBUF];
 106     size_t seedlen;
 107 } TLS1_PRF;
 108
 109 static void *kdf_tls1_prf_new(void *provctx)
 110 {
 111     TLS1_PRF *ctx;
 112
 113     if (!ossl_prov_is_running())
 114         return NULL;
 115
 116     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) != NULL)
 117         ctx->provctx = provctx;
 118     return ctx;
 119 }
 120
 121 static void kdf_tls1_prf_free(void *vctx)
 122 {
 123     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 124
 125     if (ctx != NULL) {
 126         kdf_tls1_prf_reset(ctx);
 127         OPENSSL_free(ctx);
 128     }
 129 }
 130
 131 static void kdf_tls1_prf_reset(void *vctx)
 132 {
 133     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 134     void *provctx = ctx->provctx;
 135
 136     EVP_MAC_CTX_free(ctx->P_hash);
 137     EVP_MAC_CTX_free(ctx->P_sha1);
 138     OPENSSL_clear_free(ctx->sec, ctx->seclen);
 139     OPENSSL_cleanse(ctx->seed, ctx->seedlen);
 140     memset(ctx, 0, sizeof(*ctx));
 141     ctx->provctx = provctx;
 142 }
 143
 144 static void *kdf_tls1_prf_dup(void *vctx)
 145 {
 146     const TLS1_PRF *src = (const TLS1_PRF *)vctx;
 147     TLS1_PRF *dest;
 148
 149     dest = kdf_tls1_prf_new(src->provctx);
 150     if (dest != NULL) {
 151         if (src->P_hash != NULL
 152                     && (dest->P_hash = EVP_MAC_CTX_dup(src->P_hash)) == NULL)
 153             goto err;
 154         if (src->P_sha1 != NULL
 155                     && (dest->P_sha1 = EVP_MAC_CTX_dup(src->P_sha1)) == NULL)
 156             goto err;
 157         if (!ossl_prov_memdup(src->sec, src->seclen, &dest->sec, &dest->seclen))
 158             goto err;
 159         memcpy(dest->seed, src->seed, src->seedlen);
 160         dest->seedlen = src->seedlen;
 161     }
 162     return dest;
 163
 164  err:
 165     kdf_tls1_prf_free(dest);
 166     return NULL;
 167 }
 168
 169 static int kdf_tls1_prf_derive(void *vctx, unsigned char *key, size_t keylen,
 170                                const OSSL_PARAM params[])
 171 {
 172     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 173     OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
 174
 175     if (!ossl_prov_is_running() || !kdf_tls1_prf_set_ctx_params(ctx, params))
 176         return 0;
 177
 178     if (ctx->P_hash == NULL) {
 179         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 180         return 0;
 181     }
 182     if (ctx->sec == NULL) {
 183         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 184         return 0;
 185     }
 186     if (ctx->seedlen == 0) {
 187         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SEED);
 188         return 0;
 189     }
 190     if (keylen == 0) {
 191         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
 192         return 0;
 193     }
 194
 195     /*
 196      * The seed buffer is prepended with a label.
 197      * If EMS mode is enforced then the label "master secret" is not allowed,
 198      * We do the check this way since the PRF is used for other purposes, as well
 199      * as "extended master secret".
 200      */
 201     if (ossl_tls1_prf_ems_check_enabled(libctx)) {
 202         if (ctx->seedlen >= TLS_MD_MASTER_SECRET_CONST_SIZE
 203                 && memcmp(ctx->seed, TLS_MD_MASTER_SECRET_CONST,
 204                           TLS_MD_MASTER_SECRET_CONST_SIZE) == 0) {
 205             ERR_raise(ERR_LIB_PROV, PROV_R_EMS_NOT_ENABLED);
 206             return 0;
 207         }
 208     }
 209
 210     return tls1_prf_alg(ctx->P_hash, ctx->P_sha1,
 211                         ctx->sec, ctx->seclen,
 212                         ctx->seed, ctx->seedlen,
 213                         key, keylen);
 214 }
 215
 216 static int kdf_tls1_prf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 217 {
 218     const OSSL_PARAM *p;
 219     TLS1_PRF *ctx = vctx;
 220     OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
 221
 222     if (params == NULL)
 223         return 1;
 224
 225     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL) {
 226         if (OPENSSL_strcasecmp(p->data, SN_md5_sha1) == 0) {
 227             if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
 228                                                    OSSL_MAC_NAME_HMAC,
 229                                                    NULL, SN_md5, libctx)
 230                 || !ossl_prov_macctx_load_from_params(&ctx->P_sha1, params,
 231                                                       OSSL_MAC_NAME_HMAC,
 232                                                       NULL, SN_sha1, libctx))
 233                 return 0;
 234         } else {
 235             EVP_MAC_CTX_free(ctx->P_sha1);
 236             if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
 237                                                    OSSL_MAC_NAME_HMAC,
 238                                                    NULL, NULL, libctx))
 239                 return 0;
 240         }
 241     }
 242
 243     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL) {
 244         OPENSSL_clear_free(ctx->sec, ctx->seclen);
 245         ctx->sec = NULL;
 246         if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->sec, 0, &ctx->seclen))
 247             return 0;
 248     }
 249     /* The seed fields concatenate, so process them all */
 250     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED)) != NULL) {
 251         for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
 252                                                       OSSL_KDF_PARAM_SEED)) {
 253             const void *q = ctx->seed + ctx->seedlen;
 254             size_t sz = 0;
 255
 256             if (p->data_size != 0
 257                 && p->data != NULL
 258                 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
 259                                                 TLS1_PRF_MAXBUF - ctx->seedlen,
 260                                                 &sz))
 261                 return 0;
 262             ctx->seedlen += sz;
 263         }
 264     }
 265     return 1;
 266 }
 267
 268 static const OSSL_PARAM *kdf_tls1_prf_settable_ctx_params(
 269         ossl_unused void *ctx, ossl_unused void *provctx)
 270 {
 271     static const OSSL_PARAM known_settable_ctx_params[] = {
 272         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 273         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 274         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
 275         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
 276         OSSL_PARAM_END
 277     };
 278     return known_settable_ctx_params;
 279 }
 280
 281 static int kdf_tls1_prf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 282 {
 283     OSSL_PARAM *p;
 284
 285     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 286         return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 287     return -2;
 288 }
 289
 290 static const OSSL_PARAM *kdf_tls1_prf_gettable_ctx_params(
 291         ossl_unused void *ctx, ossl_unused void *provctx)
 292 {
 293     static const OSSL_PARAM known_gettable_ctx_params[] = {
 294         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 295         OSSL_PARAM_END
 296     };
 297     return known_gettable_ctx_params;
 298 }
 299
 300 const OSSL_DISPATCH ossl_kdf_tls1_prf_functions[] = {
 301     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_tls1_prf_new },
 302     { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_tls1_prf_dup },
 303     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_tls1_prf_free },
 304     { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_tls1_prf_reset },
 305     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_tls1_prf_derive },
 306     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 307       (void(*)(void))kdf_tls1_prf_settable_ctx_params },
 308     { OSSL_FUNC_KDF_SET_CTX_PARAMS,
 309       (void(*)(void))kdf_tls1_prf_set_ctx_params },
 310     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 311       (void(*)(void))kdf_tls1_prf_gettable_ctx_params },
 312     { OSSL_FUNC_KDF_GET_CTX_PARAMS,
 313       (void(*)(void))kdf_tls1_prf_get_ctx_params },
 314     OSSL_DISPATCH_END
 315 };
 316
 317 /*
 318  * Refer to "The TLS Protocol Version 1.0" Section 5
 319  * (https://tools.ietf.org/html/rfc2246#section-5) and
 320  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
 321  * (https://tools.ietf.org/html/rfc5246#section-5).
 322  *
 323  * P_<hash> is an expansion function that uses a single hash function to expand
 324  * a secret and seed into an arbitrary quantity of output:
 325  *
 326  *   P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
 327  *                            HMAC_<hash>(secret, A(2) + seed) +
 328  *                            HMAC_<hash>(secret, A(3) + seed) + ...
 329  *
 330  * where + indicates concatenation.  P_<hash> can be iterated as many times as
 331  * is necessary to produce the required quantity of data.
 332  *
 333  * A(i) is defined as:
 334  *     A(0) = seed
 335  *     A(i) = HMAC_<hash>(secret, A(i-1))
 336  */
 337 static int tls1_prf_P_hash(EVP_MAC_CTX *ctx_init,
 338                            const unsigned char *sec, size_t sec_len,
 339                            const unsigned char *seed, size_t seed_len,
 340                            unsigned char *out, size_t olen)
 341 {
 342     size_t chunk;
 343     EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL;
 344     unsigned char Ai[EVP_MAX_MD_SIZE];
 345     size_t Ai_len;
 346     int ret = 0;
 347
 348     if (!EVP_MAC_init(ctx_init, sec, sec_len, NULL))
 349         goto err;
 350     chunk = EVP_MAC_CTX_get_mac_size(ctx_init);
 351     if (chunk == 0)
 352         goto err;
 353     /* A(0) = seed */
 354     ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
 355     if (ctx_Ai == NULL)
 356         goto err;
 357     if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
 358         goto err;
 359
 360     for (;;) {
 361         /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
 362         if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len, sizeof(Ai)))
 363             goto err;
 364         EVP_MAC_CTX_free(ctx_Ai);
 365         ctx_Ai = NULL;
 366
 367         /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
 368         ctx = EVP_MAC_CTX_dup(ctx_init);
 369         if (ctx == NULL)
 370             goto err;
 371         if (!EVP_MAC_update(ctx, Ai, Ai_len))
 372             goto err;
 373         /* save state for calculating next A(i) value */
 374         if (olen > chunk) {
 375             ctx_Ai = EVP_MAC_CTX_dup(ctx);
 376             if (ctx_Ai == NULL)
 377                 goto err;
 378         }
 379         if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
 380             goto err;
 381         if (olen <= chunk) {
 382             /* last chunk - use Ai as temp bounce buffer */
 383             if (!EVP_MAC_final(ctx, Ai, &Ai_len, sizeof(Ai)))
 384                 goto err;
 385             memcpy(out, Ai, olen);
 386             break;
 387         }
 388         if (!EVP_MAC_final(ctx, out, NULL, olen))
 389             goto err;
 390         EVP_MAC_CTX_free(ctx);
 391         ctx = NULL;
 392         out += chunk;
 393         olen -= chunk;
 394     }
 395     ret = 1;
 396  err:
 397     EVP_MAC_CTX_free(ctx);
 398     EVP_MAC_CTX_free(ctx_Ai);
 399     OPENSSL_cleanse(Ai, sizeof(Ai));
 400     return ret;
 401 }
 402
 403 /*
 404  * Refer to "The TLS Protocol Version 1.0" Section 5
 405  * (https://tools.ietf.org/html/rfc2246#section-5) and
 406  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
 407  * (https://tools.ietf.org/html/rfc5246#section-5).
 408  *
 409  * For TLS v1.0 and TLS v1.1:
 410  *
 411  *   PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
 412  *                              P_SHA-1(S2, label + seed)
 413  *
 414  * S1 is taken from the first half of the secret, S2 from the second half.
 415  *
 416  *   L_S = length in bytes of secret;
 417  *   L_S1 = L_S2 = ceil(L_S / 2);
 418  *
 419  * For TLS v1.2:
 420  *
 421  *   PRF(secret, label, seed) = P_<hash>(secret, label + seed)
 422  */
 423 static int tls1_prf_alg(EVP_MAC_CTX *mdctx, EVP_MAC_CTX *sha1ctx,
 424                         const unsigned char *sec, size_t slen,
 425                         const unsigned char *seed, size_t seed_len,
 426                         unsigned char *out, size_t olen)
 427 {
 428     if (sha1ctx != NULL) {
 429         /* TLS v1.0 and TLS v1.1 */
 430         size_t i;
 431         unsigned char *tmp;
 432         /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
 433         size_t L_S1 = (slen + 1) / 2;
 434         size_t L_S2 = L_S1;
 435
 436         if (!tls1_prf_P_hash(mdctx, sec, L_S1,
 437                              seed, seed_len, out, olen))
 438             return 0;
 439
 440         if ((tmp = OPENSSL_malloc(olen)) == NULL)
 441             return 0;
 442
 443         if (!tls1_prf_P_hash(sha1ctx, sec + slen - L_S2, L_S2,
 444                              seed, seed_len, tmp, olen)) {
 445             OPENSSL_clear_free(tmp, olen);
 446             return 0;
 447         }
 448         for (i = 0; i < olen; i++)
 449             out[i] ^= tmp[i];
 450         OPENSSL_clear_free(tmp, olen);
 451         return 1;
 452     }
 453
 454     /* TLS v1.2 */
 455     if (!tls1_prf_P_hash(mdctx, sec, slen, seed, seed_len, out, olen))
 456         return 0;
 457
 458     return 1;
 459 }