providers/common/kdfs/tls1_prf.c

   1 /*
   2  * Copyright 2016-2019 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 "internal/cryptlib.h"
  56 #include "internal/numbers.h"
  57 #include "internal/evp_int.h"
  58 #include "internal/provider_ctx.h"
  59 #include "internal/providercommonerr.h"
  60 #include "internal/provider_algs.h"
  61 #include "internal/provider_util.h"
  62 #include "e_os.h"
  63
  64 static OSSL_OP_kdf_newctx_fn kdf_tls1_prf_new;
  65 static OSSL_OP_kdf_freectx_fn kdf_tls1_prf_free;
  66 static OSSL_OP_kdf_reset_fn kdf_tls1_prf_reset;
  67 static OSSL_OP_kdf_derive_fn kdf_tls1_prf_derive;
  68 static OSSL_OP_kdf_settable_ctx_params_fn kdf_tls1_prf_settable_ctx_params;
  69 static OSSL_OP_kdf_set_ctx_params_fn kdf_tls1_prf_set_ctx_params;
  70
  71 static int tls1_prf_alg(EVP_MAC_CTX *mdctx, EVP_MAC_CTX *sha1ctx,
  72                         const unsigned char *sec, size_t slen,
  73                         const unsigned char *seed, size_t seed_len,
  74                         unsigned char *out, size_t olen);
  75
  76 #define TLS1_PRF_MAXBUF 1024
  77
  78 /* TLS KDF kdf context structure */
  79 typedef struct {
  80     void *provctx;
  81
  82     /* MAC context for the main digest */
  83     EVP_MAC_CTX *P_hash;
  84     /* MAC context for SHA1 for the MD5/SHA-1 combined PRF */
  85     EVP_MAC_CTX *P_sha1;
  86
  87     /* Secret value to use for PRF */
  88     unsigned char *sec;
  89     size_t seclen;
  90     /* Buffer of concatenated seed data */
  91     unsigned char seed[TLS1_PRF_MAXBUF];
  92     size_t seedlen;
  93 } TLS1_PRF;
  94
  95 static void *kdf_tls1_prf_new(void *provctx)
  96 {
  97     TLS1_PRF *ctx;
  98
  99     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
 100         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 101     ctx->provctx = provctx;
 102     return ctx;
 103 }
 104
 105 static void kdf_tls1_prf_free(void *vctx)
 106 {
 107     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 108
 109     kdf_tls1_prf_reset(ctx);
 110     OPENSSL_free(ctx);
 111 }
 112
 113 static void kdf_tls1_prf_reset(void *vctx)
 114 {
 115     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 116
 117     EVP_MAC_CTX_free(ctx->P_hash);
 118     EVP_MAC_CTX_free(ctx->P_sha1);
 119     OPENSSL_clear_free(ctx->sec, ctx->seclen);
 120     OPENSSL_cleanse(ctx->seed, ctx->seedlen);
 121     memset(ctx, 0, sizeof(*ctx));
 122 }
 123
 124 static int kdf_tls1_prf_derive(void *vctx, unsigned char *key,
 125                                size_t keylen)
 126 {
 127     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 128
 129     if (ctx->P_hash == NULL) {
 130         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 131         return 0;
 132     }
 133     if (ctx->sec == NULL) {
 134         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 135         return 0;
 136     }
 137     if (ctx->seedlen == 0) {
 138         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SEED);
 139         return 0;
 140     }
 141
 142     return tls1_prf_alg(ctx->P_hash, ctx->P_sha1,
 143                         ctx->sec, ctx->seclen,
 144                         ctx->seed, ctx->seedlen,
 145                         key, keylen);
 146 }
 147
 148 static EVP_MAC_CTX *kdf_tls1_prf_mkmacctx(OPENSSL_CTX *libctx,
 149                                           const char *mdname,
 150                                           const OSSL_PARAM params[])
 151 {
 152     const OSSL_PARAM *p;
 153     OSSL_PARAM mac_params[5], *mp = mac_params;
 154     const char *properties = NULL;
 155     /* TODO(3.0) rethink "flags", also see hmac.c in providers */
 156     int mac_flags = EVP_MD_CTX_FLAG_NON_FIPS_ALLOW;
 157     EVP_MAC_CTX *macctx = NULL;
 158
 159     *mp++ = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_DIGEST,
 160                                              (char *)mdname, 0);
 161 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODE)
 162     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_ENGINE)) != NULL)
 163         *mp++ = *p;
 164 #endif
 165     if ((p = OSSL_PARAM_locate_const(params,
 166                                      OSSL_KDF_PARAM_PROPERTIES)) != NULL) {
 167         properties = p->data;
 168         *mp++ = *p;
 169     }
 170     *mp++ = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_FLAGS, &mac_flags);
 171     *mp = OSSL_PARAM_construct_end();
 172
 173     /* Implicit fetch */
 174     {
 175         EVP_MAC *mac = EVP_MAC_fetch(libctx, OSSL_MAC_NAME_HMAC, properties);
 176
 177         macctx = EVP_MAC_CTX_new(mac);
 178         /* The context holds on to the MAC */
 179         EVP_MAC_free(mac);
 180         if (macctx == NULL)
 181             goto err;
 182     }
 183
 184     if (EVP_MAC_CTX_set_params(macctx, mac_params))
 185         goto done;
 186  err:
 187     EVP_MAC_CTX_free(macctx);
 188     macctx = NULL;
 189  done:
 190     return macctx;
 191 }
 192
 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     OPENSSL_CTX *libctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
 198
 199     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL) {
 200         EVP_MAC_CTX_free(ctx->P_hash);
 201         EVP_MAC_CTX_free(ctx->P_sha1);
 202         if (strcasecmp(p->data, SN_md5_sha1) == 0) {
 203             ctx->P_hash = kdf_tls1_prf_mkmacctx(libctx, SN_md5, params);
 204             ctx->P_sha1 = kdf_tls1_prf_mkmacctx(libctx, SN_sha1, params);
 205         } else {
 206             ctx->P_hash = kdf_tls1_prf_mkmacctx(libctx, p->data, params);
 207         }
 208     }
 209
 210     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL) {
 211         OPENSSL_clear_free(ctx->sec, ctx->seclen);
 212         ctx->sec = NULL;
 213         if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->sec, 0, &ctx->seclen))
 214             return 0;
 215     }
 216     /* The seed fields concatenate, so process them all */
 217     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED)) != NULL) {
 218         OPENSSL_cleanse(ctx->seed, ctx->seedlen);
 219         ctx->seedlen = 0;
 220
 221         for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
 222                                                       OSSL_KDF_PARAM_SEED)) {
 223             const void *q = ctx->seed + ctx->seedlen;
 224             size_t sz = 0;
 225
 226             if (p->data_size != 0
 227                 && p->data != NULL
 228                 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
 229                                                 TLS1_PRF_MAXBUF - ctx->seedlen,
 230                                                 &sz))
 231                 return 0;
 232             ctx->seedlen += sz;
 233         }
 234     }
 235     return 1;
 236 }
 237
 238 static const OSSL_PARAM *kdf_tls1_prf_settable_ctx_params(void)
 239 {
 240     static const OSSL_PARAM known_settable_ctx_params[] = {
 241         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 242         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 243         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
 244         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
 245         OSSL_PARAM_END
 246     };
 247     return known_settable_ctx_params;
 248 }
 249
 250 static int kdf_tls1_prf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 251 {
 252     OSSL_PARAM *p;
 253
 254     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 255         return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 256     return -2;
 257 }
 258
 259 static const OSSL_PARAM *kdf_tls1_prf_gettable_ctx_params(void)
 260 {
 261     static const OSSL_PARAM known_gettable_ctx_params[] = {
 262         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 263         OSSL_PARAM_END
 264     };
 265     return known_gettable_ctx_params;
 266 }
 267
 268 const OSSL_DISPATCH kdf_tls1_prf_functions[] = {
 269     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_tls1_prf_new },
 270     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_tls1_prf_free },
 271     { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_tls1_prf_reset },
 272     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_tls1_prf_derive },
 273     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 274       (void(*)(void))kdf_tls1_prf_settable_ctx_params },
 275     { OSSL_FUNC_KDF_SET_CTX_PARAMS,
 276       (void(*)(void))kdf_tls1_prf_set_ctx_params },
 277     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 278       (void(*)(void))kdf_tls1_prf_gettable_ctx_params },
 279     { OSSL_FUNC_KDF_GET_CTX_PARAMS,
 280       (void(*)(void))kdf_tls1_prf_get_ctx_params },
 281     { 0, NULL }
 282 };
 283
 284 /*
 285  * Refer to "The TLS Protocol Version 1.0" Section 5
 286  * (https://tools.ietf.org/html/rfc2246#section-5) and
 287  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
 288  * (https://tools.ietf.org/html/rfc5246#section-5).
 289  *
 290  * P_<hash> is an expansion function that uses a single hash function to expand
 291  * a secret and seed into an arbitrary quantity of output:
 292  *
 293  *   P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
 294  *                            HMAC_<hash>(secret, A(2) + seed) +
 295  *                            HMAC_<hash>(secret, A(3) + seed) + ...
 296  *
 297  * where + indicates concatenation.  P_<hash> can be iterated as many times as
 298  * is necessary to produce the required quantity of data.
 299  *
 300  * A(i) is defined as:
 301  *     A(0) = seed
 302  *     A(i) = HMAC_<hash>(secret, A(i-1))
 303  */
 304 static int tls1_prf_P_hash(EVP_MAC_CTX *ctx_init,
 305                            const unsigned char *sec, size_t sec_len,
 306                            const unsigned char *seed, size_t seed_len,
 307                            unsigned char *out, size_t olen)
 308 {
 309     size_t chunk;
 310     EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL;
 311     unsigned char Ai[EVP_MAX_MD_SIZE];
 312     size_t Ai_len;
 313     int ret = 0;
 314     OSSL_PARAM params[2], *p = params;
 315
 316     *p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
 317                                              (void *)sec, sec_len);
 318     *p = OSSL_PARAM_construct_end();
 319     if (!EVP_MAC_CTX_set_params(ctx_init, params))
 320         goto err;
 321     if (!EVP_MAC_init(ctx_init))
 322         goto err;
 323     chunk = EVP_MAC_size(ctx_init);
 324     if (chunk == 0)
 325         goto err;
 326     /* A(0) = seed */
 327     ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
 328     if (ctx_Ai == NULL)
 329         goto err;
 330     if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
 331         goto err;
 332
 333     for (;;) {
 334         /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
 335         if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len, sizeof(Ai)))
 336             goto err;
 337         EVP_MAC_CTX_free(ctx_Ai);
 338         ctx_Ai = NULL;
 339
 340         /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
 341         ctx = EVP_MAC_CTX_dup(ctx_init);
 342         if (ctx == NULL)
 343             goto err;
 344         if (!EVP_MAC_update(ctx, Ai, Ai_len))
 345             goto err;
 346         /* save state for calculating next A(i) value */
 347         if (olen > chunk) {
 348             ctx_Ai = EVP_MAC_CTX_dup(ctx);
 349             if (ctx_Ai == NULL)
 350                 goto err;
 351         }
 352         if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
 353             goto err;
 354         if (olen <= chunk) {
 355             /* last chunk - use Ai as temp bounce buffer */
 356             if (!EVP_MAC_final(ctx, Ai, &Ai_len, sizeof(Ai)))
 357                 goto err;
 358             memcpy(out, Ai, olen);
 359             break;
 360         }
 361         if (!EVP_MAC_final(ctx, out, NULL, olen))
 362             goto err;
 363         EVP_MAC_CTX_free(ctx);
 364         ctx = NULL;
 365         out += chunk;
 366         olen -= chunk;
 367     }
 368     ret = 1;
 369  err:
 370     EVP_MAC_CTX_free(ctx);
 371     EVP_MAC_CTX_free(ctx_Ai);
 372     OPENSSL_cleanse(Ai, sizeof(Ai));
 373     return ret;
 374 }
 375
 376 /*
 377  * Refer to "The TLS Protocol Version 1.0" Section 5
 378  * (https://tools.ietf.org/html/rfc2246#section-5) and
 379  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
 380  * (https://tools.ietf.org/html/rfc5246#section-5).
 381  *
 382  * For TLS v1.0 and TLS v1.1:
 383  *
 384  *   PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
 385  *                              P_SHA-1(S2, label + seed)
 386  *
 387  * S1 is taken from the first half of the secret, S2 from the second half.
 388  *
 389  *   L_S = length in bytes of secret;
 390  *   L_S1 = L_S2 = ceil(L_S / 2);
 391  *
 392  * For TLS v1.2:
 393  *
 394  *   PRF(secret, label, seed) = P_<hash>(secret, label + seed)
 395  */
 396 static int tls1_prf_alg(EVP_MAC_CTX *mdctx, EVP_MAC_CTX *sha1ctx,
 397                         const unsigned char *sec, size_t slen,
 398                         const unsigned char *seed, size_t seed_len,
 399                         unsigned char *out, size_t olen)
 400 {
 401     if (sha1ctx != NULL) {
 402         /* TLS v1.0 and TLS v1.1 */
 403         size_t i;
 404         unsigned char *tmp;
 405         /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
 406         size_t L_S1 = (slen + 1) / 2;
 407         size_t L_S2 = L_S1;
 408
 409         if (!tls1_prf_P_hash(mdctx, sec, L_S1,
 410                              seed, seed_len, out, olen))
 411             return 0;
 412
 413         if ((tmp = OPENSSL_malloc(olen)) == NULL) {
 414             ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 415             return 0;
 416         }
 417
 418         if (!tls1_prf_P_hash(sha1ctx, sec + slen - L_S2, L_S2,
 419                              seed, seed_len, tmp, olen)) {
 420             OPENSSL_clear_free(tmp, olen);
 421             return 0;
 422         }
 423         for (i = 0; i < olen; i++)
 424             out[i] ^= tmp[i];
 425         OPENSSL_clear_free(tmp, olen);
 426         return 1;
 427     }
 428
 429     /* TLS v1.2 */
 430     if (!tls1_prf_P_hash(mdctx, sec, slen, seed, seed_len, out, olen))
 431         return 0;
 432
 433     return 1;
 434 }