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 "e_os.h"
  62
  63 static OSSL_OP_kdf_newctx_fn kdf_tls1_prf_new;
  64 static OSSL_OP_kdf_freectx_fn kdf_tls1_prf_free;
  65 static OSSL_OP_kdf_reset_fn kdf_tls1_prf_reset;
  66 static OSSL_OP_kdf_derive_fn kdf_tls1_prf_derive;
  67 static OSSL_OP_kdf_settable_ctx_params_fn kdf_tls1_prf_settable_ctx_params;
  68 static OSSL_OP_kdf_set_ctx_params_fn kdf_tls1_prf_set_ctx_params;
  69
  70 static int tls1_prf_alg(const EVP_MD *md, const EVP_MD *sha1,
  71                         const unsigned char *sec, size_t slen,
  72                         const unsigned char *seed, size_t seed_len,
  73                         unsigned char *out, size_t olen);
  74
  75 #define TLS1_PRF_MAXBUF 1024
  76
  77 /* TLS KDF kdf context structure */
  78 typedef struct {
  79     void *provctx;
  80     /* Digest to use for PRF */
  81     EVP_MD *md;
  82     /* Second digest for the MD5/SHA-1 combined PRF */
  83     EVP_MD *sha1;
  84     /* Secret value to use for PRF */
  85     unsigned char *sec;
  86     size_t seclen;
  87     /* Buffer of concatenated seed data */
  88     unsigned char seed[TLS1_PRF_MAXBUF];
  89     size_t seedlen;
  90 } TLS1_PRF;
  91
  92 static void *kdf_tls1_prf_new(void *provctx)
  93 {
  94     TLS1_PRF *ctx;
  95
  96     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
  97         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
  98     ctx->provctx = provctx;
  99     return ctx;
 100 }
 101
 102 static void kdf_tls1_prf_free(void *vctx)
 103 {
 104     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 105
 106     kdf_tls1_prf_reset(ctx);
 107     EVP_MD_meth_free(ctx->sha1);
 108     EVP_MD_meth_free(ctx->md);
 109     OPENSSL_free(ctx);
 110 }
 111
 112 static void kdf_tls1_prf_reset(void *vctx)
 113 {
 114     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 115
 116     OPENSSL_clear_free(ctx->sec, ctx->seclen);
 117     OPENSSL_cleanse(ctx->seed, ctx->seedlen);
 118     memset(ctx, 0, sizeof(*ctx));
 119 }
 120
 121 static int kdf_tls1_prf_derive(void *vctx, unsigned char *key,
 122                                size_t keylen)
 123 {
 124     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
 125
 126     if (ctx->md == NULL) {
 127         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 128         return 0;
 129     }
 130     if (ctx->sec == NULL) {
 131         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 132         return 0;
 133     }
 134     if (ctx->seedlen == 0) {
 135         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SEED);
 136         return 0;
 137     }
 138     return tls1_prf_alg(ctx->md, ctx->sha1, ctx->sec, ctx->seclen,
 139                         ctx->seed, ctx->seedlen,
 140                         key, keylen);
 141 }
 142
 143 static int kdf_tls1_prf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 144 {
 145     const OSSL_PARAM *p;
 146     TLS1_PRF *ctx = vctx;
 147     EVP_MD *md, *sha = NULL;
 148     const char *properties = NULL, *name;
 149
 150     /* Grab search properties, this should be before the digest lookup */
 151     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_PROPERTIES))
 152         != NULL) {
 153         if (p->data_type != OSSL_PARAM_UTF8_STRING)
 154             return 0;
 155         properties = p->data;
 156     }
 157     /* Handle aliasing of digest parameter names */
 158     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL) {
 159         if (p->data_type != OSSL_PARAM_UTF8_STRING)
 160             return 0;
 161         name = p->data;
 162         if (strcasecmp(name, SN_md5_sha1) == 0) {
 163             sha = EVP_MD_fetch(PROV_LIBRARY_CONTEXT_OF(ctx->provctx), SN_sha1,
 164                                properties);
 165             if (sha == NULL) {
 166                 ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_LOAD_SHA1);
 167                 return 0;
 168             }
 169             name = SN_md5;
 170         }
 171         md = EVP_MD_fetch(PROV_LIBRARY_CONTEXT_OF(ctx->provctx), name,
 172                           properties);
 173         if (md == NULL) {
 174             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_DIGEST);
 175             EVP_MD_meth_free(sha);
 176             return 0;
 177         }
 178         EVP_MD_meth_free(ctx->sha1);
 179         EVP_MD_meth_free(ctx->md);
 180         ctx->md = md;
 181         ctx->sha1 = sha;
 182     }
 183
 184     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL) {
 185         OPENSSL_clear_free(ctx->sec, ctx->seclen);
 186         ctx->sec = NULL;
 187         if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->sec, 0, &ctx->seclen))
 188             return 0;
 189     }
 190     /* The seed fields concatenate, so process them all */
 191     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED)) != NULL) {
 192         OPENSSL_cleanse(ctx->seed, ctx->seedlen);
 193         ctx->seedlen = 0;
 194
 195         for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
 196                                                       OSSL_KDF_PARAM_SEED)) {
 197             const void *q = ctx->seed + ctx->seedlen;
 198             size_t sz = 0;
 199
 200             if (p->data_size != 0
 201                 && p->data != NULL
 202                 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
 203                                                 TLS1_PRF_MAXBUF - ctx->seedlen,
 204                                                 &sz))
 205                 return 0;
 206             ctx->seedlen += sz;
 207         }
 208     }
 209     return 1;
 210 }
 211
 212 static const OSSL_PARAM *kdf_tls1_prf_settable_ctx_params(void)
 213 {
 214     static const OSSL_PARAM known_settable_ctx_params[] = {
 215         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 216         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 217         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
 218         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
 219         OSSL_PARAM_END
 220     };
 221     return known_settable_ctx_params;
 222 }
 223
 224 static int kdf_tls1_prf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 225 {
 226     OSSL_PARAM *p;
 227
 228     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 229         return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 230     return -2;
 231 }
 232
 233 static const OSSL_PARAM *kdf_tls1_prf_gettable_ctx_params(void)
 234 {
 235     static const OSSL_PARAM known_gettable_ctx_params[] = {
 236         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 237         OSSL_PARAM_END
 238     };
 239     return known_gettable_ctx_params;
 240 }
 241
 242 const OSSL_DISPATCH kdf_tls1_prf_functions[] = {
 243     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_tls1_prf_new },
 244     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_tls1_prf_free },
 245     { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_tls1_prf_reset },
 246     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_tls1_prf_derive },
 247     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 248       (void(*)(void))kdf_tls1_prf_settable_ctx_params },
 249     { OSSL_FUNC_KDF_SET_CTX_PARAMS,
 250       (void(*)(void))kdf_tls1_prf_set_ctx_params },
 251     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 252       (void(*)(void))kdf_tls1_prf_gettable_ctx_params },
 253     { OSSL_FUNC_KDF_GET_CTX_PARAMS,
 254       (void(*)(void))kdf_tls1_prf_get_ctx_params },
 255     { 0, NULL }
 256 };
 257
 258 /*
 259  * Refer to "The TLS Protocol Version 1.0" Section 5
 260  * (https://tools.ietf.org/html/rfc2246#section-5) and
 261  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
 262  * (https://tools.ietf.org/html/rfc5246#section-5).
 263  *
 264  * P_<hash> is an expansion function that uses a single hash function to expand
 265  * a secret and seed into an arbitrary quantity of output:
 266  *
 267  *   P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
 268  *                            HMAC_<hash>(secret, A(2) + seed) +
 269  *                            HMAC_<hash>(secret, A(3) + seed) + ...
 270  *
 271  * where + indicates concatenation.  P_<hash> can be iterated as many times as
 272  * is necessary to produce the required quantity of data.
 273  *
 274  * A(i) is defined as:
 275  *     A(0) = seed
 276  *     A(i) = HMAC_<hash>(secret, A(i-1))
 277  */
 278 static int tls1_prf_P_hash(const EVP_MD *md,
 279                            const unsigned char *sec, size_t sec_len,
 280                            const unsigned char *seed, size_t seed_len,
 281                            unsigned char *out, size_t olen)
 282 {
 283     size_t chunk;
 284     EVP_MAC *mac = NULL;
 285     EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL, *ctx_init = NULL;
 286     unsigned char Ai[EVP_MAX_MD_SIZE];
 287     size_t Ai_len;
 288     int ret = 0;
 289     OSSL_PARAM params[4];
 290     int mac_flags;
 291     const char *mdname = EVP_MD_name(md);
 292
 293     mac = EVP_MAC_fetch(NULL, OSSL_MAC_NAME_HMAC, NULL); /* Implicit fetch */
 294     ctx_init = EVP_MAC_CTX_new(mac);
 295     if (ctx_init == NULL)
 296         goto err;
 297
 298     /* TODO(3.0) rethink "flags", also see hmac.c in providers */
 299     mac_flags = EVP_MD_CTX_FLAG_NON_FIPS_ALLOW;
 300     params[0] = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_FLAGS, &mac_flags);
 301     params[1] = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_DIGEST,
 302                                                  (char *)mdname, 0);
 303     params[2] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
 304                                                   (void *)sec, sec_len);
 305     params[3] = OSSL_PARAM_construct_end();
 306     if (!EVP_MAC_CTX_set_params(ctx_init, params))
 307         goto err;
 308     if (!EVP_MAC_init(ctx_init))
 309         goto err;
 310     chunk = EVP_MAC_size(ctx_init);
 311     if (chunk == 0)
 312         goto err;
 313     /* A(0) = seed */
 314     ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
 315     if (ctx_Ai == NULL)
 316         goto err;
 317     if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
 318         goto err;
 319
 320     for (;;) {
 321         /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
 322         if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len, sizeof(Ai)))
 323             goto err;
 324         EVP_MAC_CTX_free(ctx_Ai);
 325         ctx_Ai = NULL;
 326
 327         /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
 328         ctx = EVP_MAC_CTX_dup(ctx_init);
 329         if (ctx == NULL)
 330             goto err;
 331         if (!EVP_MAC_update(ctx, Ai, Ai_len))
 332             goto err;
 333         /* save state for calculating next A(i) value */
 334         if (olen > chunk) {
 335             ctx_Ai = EVP_MAC_CTX_dup(ctx);
 336             if (ctx_Ai == NULL)
 337                 goto err;
 338         }
 339         if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
 340             goto err;
 341         if (olen <= chunk) {
 342             /* last chunk - use Ai as temp bounce buffer */
 343             if (!EVP_MAC_final(ctx, Ai, &Ai_len, sizeof(Ai)))
 344                 goto err;
 345             memcpy(out, Ai, olen);
 346             break;
 347         }
 348         if (!EVP_MAC_final(ctx, out, NULL, olen))
 349             goto err;
 350         EVP_MAC_CTX_free(ctx);
 351         ctx = NULL;
 352         out += chunk;
 353         olen -= chunk;
 354     }
 355     ret = 1;
 356  err:
 357     EVP_MAC_CTX_free(ctx);
 358     EVP_MAC_CTX_free(ctx_Ai);
 359     EVP_MAC_CTX_free(ctx_init);
 360     EVP_MAC_free(mac);
 361     OPENSSL_cleanse(Ai, sizeof(Ai));
 362     return ret;
 363 }
 364
 365 /*
 366  * Refer to "The TLS Protocol Version 1.0" Section 5
 367  * (https://tools.ietf.org/html/rfc2246#section-5) and
 368  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
 369  * (https://tools.ietf.org/html/rfc5246#section-5).
 370  *
 371  * For TLS v1.0 and TLS v1.1:
 372  *
 373  *   PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
 374  *                              P_SHA-1(S2, label + seed)
 375  *
 376  * S1 is taken from the first half of the secret, S2 from the second half.
 377  *
 378  *   L_S = length in bytes of secret;
 379  *   L_S1 = L_S2 = ceil(L_S / 2);
 380  *
 381  * For TLS v1.2:
 382  *
 383  *   PRF(secret, label, seed) = P_<hash>(secret, label + seed)
 384  */
 385 static int tls1_prf_alg(const EVP_MD *md, const EVP_MD *sha1,
 386                         const unsigned char *sec, size_t slen,
 387                         const unsigned char *seed, size_t seed_len,
 388                         unsigned char *out, size_t olen)
 389 {
 390     if (sha1 != NULL) {
 391         /* TLS v1.0 and TLS v1.1 */
 392         size_t i;
 393         unsigned char *tmp;
 394         /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
 395         size_t L_S1 = (slen + 1) / 2;
 396         size_t L_S2 = L_S1;
 397
 398         if (!tls1_prf_P_hash(md, sec, L_S1,
 399                              seed, seed_len, out, olen))
 400             return 0;
 401
 402         if ((tmp = OPENSSL_malloc(olen)) == NULL) {
 403             ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 404             return 0;
 405         }
 406         if (!tls1_prf_P_hash(sha1, sec + slen - L_S2, L_S2,
 407                              seed, seed_len, tmp, olen)) {
 408             OPENSSL_clear_free(tmp, olen);
 409             return 0;
 410         }
 411         for (i = 0; i < olen; i++)
 412             out[i] ^= tmp[i];
 413         OPENSSL_clear_free(tmp, olen);
 414         return 1;
 415     }
 416
 417     /* TLS v1.2 */
 418     if (!tls1_prf_P_hash(md, sec, slen, seed, seed_len, out, olen))
 419         return 0;
 420
 421     return 1;
 422 }