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 "crypto/evp.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 int kdf_tls1_prf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 149 {
 150     const OSSL_PARAM *p;
 151     TLS1_PRF *ctx = vctx;
 152     OPENSSL_CTX *libctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
 153
 154     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL) {
 155         if (strcasecmp(p->data, SN_md5_sha1) == 0) {
 156             if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
 157                                                    OSSL_MAC_NAME_HMAC,
 158                                                    NULL, SN_md5, libctx)
 159                 || !ossl_prov_macctx_load_from_params(&ctx->P_sha1, params,
 160                                                       OSSL_MAC_NAME_HMAC,
 161                                                       NULL, SN_sha1, libctx))
 162                 return 0;
 163         } else {
 164             EVP_MAC_CTX_free(ctx->P_sha1);
 165             if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
 166                                                    OSSL_MAC_NAME_HMAC,
 167                                                    NULL, NULL, libctx))
 168                 return 0;
 169         }
 170     }
 171
 172     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL) {
 173         OPENSSL_clear_free(ctx->sec, ctx->seclen);
 174         ctx->sec = NULL;
 175         if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->sec, 0, &ctx->seclen))
 176             return 0;
 177     }
 178     /* The seed fields concatenate, so process them all */
 179     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED)) != NULL) {
 180         OPENSSL_cleanse(ctx->seed, ctx->seedlen);
 181         ctx->seedlen = 0;
 182
 183         for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
 184                                                       OSSL_KDF_PARAM_SEED)) {
 185             const void *q = ctx->seed + ctx->seedlen;
 186             size_t sz = 0;
 187
 188             if (p->data_size != 0
 189                 && p->data != NULL
 190                 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
 191                                                 TLS1_PRF_MAXBUF - ctx->seedlen,
 192                                                 &sz))
 193                 return 0;
 194             ctx->seedlen += sz;
 195         }
 196     }
 197     return 1;
 198 }
 199
 200 static const OSSL_PARAM *kdf_tls1_prf_settable_ctx_params(void)
 201 {
 202     static const OSSL_PARAM known_settable_ctx_params[] = {
 203         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 204         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 205         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
 206         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
 207         OSSL_PARAM_END
 208     };
 209     return known_settable_ctx_params;
 210 }
 211
 212 static int kdf_tls1_prf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 213 {
 214     OSSL_PARAM *p;
 215
 216     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 217         return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 218     return -2;
 219 }
 220
 221 static const OSSL_PARAM *kdf_tls1_prf_gettable_ctx_params(void)
 222 {
 223     static const OSSL_PARAM known_gettable_ctx_params[] = {
 224         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 225         OSSL_PARAM_END
 226     };
 227     return known_gettable_ctx_params;
 228 }
 229
 230 const OSSL_DISPATCH kdf_tls1_prf_functions[] = {
 231     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_tls1_prf_new },
 232     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_tls1_prf_free },
 233     { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_tls1_prf_reset },
 234     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_tls1_prf_derive },
 235     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 236       (void(*)(void))kdf_tls1_prf_settable_ctx_params },
 237     { OSSL_FUNC_KDF_SET_CTX_PARAMS,
 238       (void(*)(void))kdf_tls1_prf_set_ctx_params },
 239     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 240       (void(*)(void))kdf_tls1_prf_gettable_ctx_params },
 241     { OSSL_FUNC_KDF_GET_CTX_PARAMS,
 242       (void(*)(void))kdf_tls1_prf_get_ctx_params },
 243     { 0, NULL }
 244 };
 245
 246 /*
 247  * Refer to "The TLS Protocol Version 1.0" Section 5
 248  * (https://tools.ietf.org/html/rfc2246#section-5) and
 249  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
 250  * (https://tools.ietf.org/html/rfc5246#section-5).
 251  *
 252  * P_<hash> is an expansion function that uses a single hash function to expand
 253  * a secret and seed into an arbitrary quantity of output:
 254  *
 255  *   P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
 256  *                            HMAC_<hash>(secret, A(2) + seed) +
 257  *                            HMAC_<hash>(secret, A(3) + seed) + ...
 258  *
 259  * where + indicates concatenation.  P_<hash> can be iterated as many times as
 260  * is necessary to produce the required quantity of data.
 261  *
 262  * A(i) is defined as:
 263  *     A(0) = seed
 264  *     A(i) = HMAC_<hash>(secret, A(i-1))
 265  */
 266 static int tls1_prf_P_hash(EVP_MAC_CTX *ctx_init,
 267                            const unsigned char *sec, size_t sec_len,
 268                            const unsigned char *seed, size_t seed_len,
 269                            unsigned char *out, size_t olen)
 270 {
 271     size_t chunk;
 272     EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL;
 273     unsigned char Ai[EVP_MAX_MD_SIZE];
 274     size_t Ai_len;
 275     int ret = 0;
 276     OSSL_PARAM params[2], *p = params;
 277
 278     *p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
 279                                              (void *)sec, sec_len);
 280     *p = OSSL_PARAM_construct_end();
 281     if (!EVP_MAC_CTX_set_params(ctx_init, params))
 282         goto err;
 283     if (!EVP_MAC_init(ctx_init))
 284         goto err;
 285     chunk = EVP_MAC_size(ctx_init);
 286     if (chunk == 0)
 287         goto err;
 288     /* A(0) = seed */
 289     ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
 290     if (ctx_Ai == NULL)
 291         goto err;
 292     if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
 293         goto err;
 294
 295     for (;;) {
 296         /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
 297         if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len, sizeof(Ai)))
 298             goto err;
 299         EVP_MAC_CTX_free(ctx_Ai);
 300         ctx_Ai = NULL;
 301
 302         /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
 303         ctx = EVP_MAC_CTX_dup(ctx_init);
 304         if (ctx == NULL)
 305             goto err;
 306         if (!EVP_MAC_update(ctx, Ai, Ai_len))
 307             goto err;
 308         /* save state for calculating next A(i) value */
 309         if (olen > chunk) {
 310             ctx_Ai = EVP_MAC_CTX_dup(ctx);
 311             if (ctx_Ai == NULL)
 312                 goto err;
 313         }
 314         if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
 315             goto err;
 316         if (olen <= chunk) {
 317             /* last chunk - use Ai as temp bounce buffer */
 318             if (!EVP_MAC_final(ctx, Ai, &Ai_len, sizeof(Ai)))
 319                 goto err;
 320             memcpy(out, Ai, olen);
 321             break;
 322         }
 323         if (!EVP_MAC_final(ctx, out, NULL, olen))
 324             goto err;
 325         EVP_MAC_CTX_free(ctx);
 326         ctx = NULL;
 327         out += chunk;
 328         olen -= chunk;
 329     }
 330     ret = 1;
 331  err:
 332     EVP_MAC_CTX_free(ctx);
 333     EVP_MAC_CTX_free(ctx_Ai);
 334     OPENSSL_cleanse(Ai, sizeof(Ai));
 335     return ret;
 336 }
 337
 338 /*
 339  * Refer to "The TLS Protocol Version 1.0" Section 5
 340  * (https://tools.ietf.org/html/rfc2246#section-5) and
 341  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
 342  * (https://tools.ietf.org/html/rfc5246#section-5).
 343  *
 344  * For TLS v1.0 and TLS v1.1:
 345  *
 346  *   PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
 347  *                              P_SHA-1(S2, label + seed)
 348  *
 349  * S1 is taken from the first half of the secret, S2 from the second half.
 350  *
 351  *   L_S = length in bytes of secret;
 352  *   L_S1 = L_S2 = ceil(L_S / 2);
 353  *
 354  * For TLS v1.2:
 355  *
 356  *   PRF(secret, label, seed) = P_<hash>(secret, label + seed)
 357  */
 358 static int tls1_prf_alg(EVP_MAC_CTX *mdctx, EVP_MAC_CTX *sha1ctx,
 359                         const unsigned char *sec, size_t slen,
 360                         const unsigned char *seed, size_t seed_len,
 361                         unsigned char *out, size_t olen)
 362 {
 363     if (sha1ctx != NULL) {
 364         /* TLS v1.0 and TLS v1.1 */
 365         size_t i;
 366         unsigned char *tmp;
 367         /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
 368         size_t L_S1 = (slen + 1) / 2;
 369         size_t L_S2 = L_S1;
 370
 371         if (!tls1_prf_P_hash(mdctx, sec, L_S1,
 372                              seed, seed_len, out, olen))
 373             return 0;
 374
 375         if ((tmp = OPENSSL_malloc(olen)) == NULL) {
 376             ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 377             return 0;
 378         }
 379
 380         if (!tls1_prf_P_hash(sha1ctx, sec + slen - L_S2, L_S2,
 381                              seed, seed_len, tmp, olen)) {
 382             OPENSSL_clear_free(tmp, olen);
 383             return 0;
 384         }
 385         for (i = 0; i < olen; i++)
 386             out[i] ^= tmp[i];
 387         OPENSSL_clear_free(tmp, olen);
 388         return 1;
 389     }
 390
 391     /* TLS v1.2 */
 392     if (!tls1_prf_P_hash(mdctx, sec, slen, seed, seed_len, out, olen))
 393         return 0;
 394
 395     return 1;
 396 }