providers/implementations/kdfs/kbkdf.c

   1 /*
   2  * Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
   3  * Copyright 2019 Red Hat, Inc.
   4  *
   5  * Licensed under the Apache License 2.0 (the "License").  You may not use
   6  * this file except in compliance with the License.  You can obtain a copy
   7  * in the file LICENSE in the source distribution or at
   8  * https://www.openssl.org/source/license.html
   9  */
  10
  11 /*
  12  * This implements https://csrc.nist.gov/publications/detail/sp/800-108/final
  13  * section 5.1 ("counter mode") and section 5.2 ("feedback mode") in both HMAC
  14  * and CMAC.  That document does not name the KDFs it defines; the name is
  15  * derived from
  16  * https://csrc.nist.gov/Projects/Cryptographic-Algorithm-Validation-Program/Key-Derivation
  17  *
  18  * Note that section 5.3 ("double-pipeline mode") is not implemented, though
  19  * it would be possible to do so in the future.
  20  *
  21  * These versions all assume the counter is used.  It would be relatively
  22  * straightforward to expose a configuration handle should the need arise.
  23  *
  24  * Variable names attempt to match those of SP800-108.
  25  */
  26
  27 #include <stdarg.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30
  31 #include <openssl/core_names.h>
  32 #include <openssl/evp.h>
  33 #include <openssl/hmac.h>
  34 #include <openssl/kdf.h>
  35 #include <openssl/params.h>
  36
  37 #include "internal/cryptlib.h"
  38 #include "crypto/evp.h"
  39 #include "internal/numbers.h"
  40 #include "prov/implementations.h"
  41 #include "prov/provider_ctx.h"
  42 #include "prov/provider_util.h"
  43 #include "prov/providercommonerr.h"
  44
  45 #include "e_os.h"
  46
  47 #define MIN(a, b) ((a) < (b)) ? (a) : (b)
  48
  49 typedef enum {
  50     COUNTER = 0,
  51     FEEDBACK
  52 } kbkdf_mode;
  53
  54 /* Our context structure. */
  55 typedef struct {
  56     void *provctx;
  57     kbkdf_mode mode;
  58     EVP_MAC_CTX *ctx_init;
  59
  60     /* Names are lowercased versions of those found in SP800-108. */
  61     unsigned char *ki;
  62     size_t ki_len;
  63     unsigned char *label;
  64     size_t label_len;
  65     unsigned char *context;
  66     size_t context_len;
  67     unsigned char *iv;
  68     size_t iv_len;
  69 } KBKDF;
  70
  71 /* Definitions needed for typechecking. */
  72 static OSSL_FUNC_kdf_newctx_fn kbkdf_new;
  73 static OSSL_FUNC_kdf_freectx_fn kbkdf_free;
  74 static OSSL_FUNC_kdf_reset_fn kbkdf_reset;
  75 static OSSL_FUNC_kdf_derive_fn kbkdf_derive;
  76 static OSSL_FUNC_kdf_settable_ctx_params_fn kbkdf_settable_ctx_params;
  77 static OSSL_FUNC_kdf_set_ctx_params_fn kbkdf_set_ctx_params;
  78
  79 /* Not all platforms have htobe32(). */
  80 static uint32_t be32(uint32_t host)
  81 {
  82     uint32_t big = 0;
  83     const union {
  84         long one;
  85         char little;
  86     } is_endian = { 1 };
  87
  88     if (!is_endian.little)
  89         return host;
  90
  91     big |= (host & 0xff000000) >> 24;
  92     big |= (host & 0x00ff0000) >> 8;
  93     big |= (host & 0x0000ff00) << 8;
  94     big |= (host & 0x000000ff) << 24;
  95     return big;
  96 }
  97
  98 static void *kbkdf_new(void *provctx)
  99 {
 100     KBKDF *ctx;
 101
 102     ctx = OPENSSL_zalloc(sizeof(*ctx));
 103     if (ctx == NULL) {
 104         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 105         return NULL;
 106     }
 107
 108     ctx->provctx = provctx;
 109     return ctx;
 110 }
 111
 112 static void kbkdf_free(void *vctx)
 113 {
 114     KBKDF *ctx = (KBKDF *)vctx;
 115
 116     if (ctx != NULL) {
 117         kbkdf_reset(ctx);
 118         OPENSSL_free(ctx);
 119     }
 120 }
 121
 122 static void kbkdf_reset(void *vctx)
 123 {
 124     KBKDF *ctx = (KBKDF *)vctx;
 125
 126     EVP_MAC_free_ctx(ctx->ctx_init);
 127     OPENSSL_clear_free(ctx->context, ctx->context_len);
 128     OPENSSL_clear_free(ctx->label, ctx->label_len);
 129     OPENSSL_clear_free(ctx->ki, ctx->ki_len);
 130     OPENSSL_clear_free(ctx->iv, ctx->iv_len);
 131     memset(ctx, 0, sizeof(*ctx));
 132 }
 133
 134 /* SP800-108 section 5.1 or section 5.2 depending on mode. */
 135 static int derive(EVP_MAC_CTX *ctx_init, kbkdf_mode mode, unsigned char *iv,
 136                   size_t iv_len, unsigned char *label, size_t label_len,
 137                   unsigned char *context, size_t context_len,
 138                   unsigned char *k_i, size_t h, uint32_t l, unsigned char *ko,
 139                   size_t ko_len)
 140 {
 141     int ret = 0;
 142     EVP_MAC_CTX *ctx = NULL;
 143     size_t written = 0, to_write, k_i_len = iv_len;
 144     const unsigned char zero = 0;
 145     uint32_t counter, i;
 146
 147     /* Setup K(0) for feedback mode. */
 148     if (iv_len > 0)
 149         memcpy(k_i, iv, iv_len);
 150
 151     for (counter = 1; written < ko_len; counter++) {
 152         i = be32(counter);
 153
 154         ctx = EVP_MAC_dup_ctx(ctx_init);
 155         if (ctx == NULL)
 156             goto done;
 157
 158         /* Perform feedback, if appropriate. */
 159         if (mode == FEEDBACK && !EVP_MAC_update(ctx, k_i, k_i_len))
 160             goto done;
 161
 162         if (!EVP_MAC_update(ctx, (unsigned char *)&i, 4)
 163             || !EVP_MAC_update(ctx, label, label_len)
 164             || !EVP_MAC_update(ctx, &zero, 1)
 165             || !EVP_MAC_update(ctx, context, context_len)
 166             || !EVP_MAC_update(ctx, (unsigned char *)&l, 4)
 167             || !EVP_MAC_final(ctx, k_i, NULL, h))
 168             goto done;
 169
 170         to_write = ko_len - written;
 171         memcpy(ko + written, k_i, MIN(to_write, h));
 172         written += h;
 173
 174         k_i_len = h;
 175         EVP_MAC_free_ctx(ctx);
 176         ctx = NULL;
 177     }
 178
 179     ret = 1;
 180 done:
 181     EVP_MAC_free_ctx(ctx);
 182     return ret;
 183 }
 184
 185 static int kbkdf_derive(void *vctx, unsigned char *key, size_t keylen)
 186 {
 187     KBKDF *ctx = (KBKDF *)vctx;
 188     int ret = 0;
 189     unsigned char *k_i = NULL;
 190     uint32_t l = be32(keylen * 8);
 191     size_t h = 0;
 192
 193     /* label, context, and iv are permitted to be empty.  Check everything
 194      * else. */
 195     if (ctx->ctx_init == NULL) {
 196         if (ctx->ki_len == 0 || ctx->ki == NULL) {
 197             ERR_raise(ERR_LIB_PROV, PROV_R_NO_KEY_SET);
 198             return 0;
 199         }
 200         /* Could either be missing MAC or missing message digest or missing
 201          * cipher - arbitrarily, I pick this one. */
 202         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MAC);
 203         return 0;
 204     }
 205
 206     h = EVP_MAC_size(ctx->ctx_init);
 207     if (h == 0)
 208         goto done;
 209     if (ctx->iv_len != 0 && ctx->iv_len != h) {
 210         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_SEED_LENGTH);
 211         goto done;
 212     }
 213
 214     k_i = OPENSSL_zalloc(h);
 215     if (k_i == NULL)
 216         goto done;
 217
 218     ret = derive(ctx->ctx_init, ctx->mode, ctx->iv, ctx->iv_len, ctx->label,
 219                  ctx->label_len, ctx->context, ctx->context_len, k_i, h, l,
 220                  key, keylen);
 221 done:
 222     if (ret != 1)
 223         OPENSSL_cleanse(key, keylen);
 224     OPENSSL_clear_free(k_i, h);
 225     return ret;
 226 }
 227
 228 static int kbkdf_set_buffer(unsigned char **out, size_t *out_len,
 229                             const OSSL_PARAM *p)
 230 {
 231     if (p->data == NULL || p->data_size == 0)
 232         return 1;
 233
 234     OPENSSL_clear_free(*out, *out_len);
 235     *out = NULL;
 236     return OSSL_PARAM_get_octet_string(p, (void **)out, 0, out_len);
 237 }
 238
 239 static int kbkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 240 {
 241     KBKDF *ctx = (KBKDF *)vctx;
 242     OPENSSL_CTX *libctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
 243     const OSSL_PARAM *p;
 244     OSSL_PARAM mparams[2];
 245
 246     if (!ossl_prov_macctx_load_from_params(&ctx->ctx_init, params, NULL,
 247                                            NULL, NULL, libctx))
 248         return 0;
 249     else if (ctx->ctx_init != NULL
 250              && !EVP_MAC_is_a(EVP_MAC_get_ctx_mac(ctx->ctx_init),
 251                               OSSL_MAC_NAME_HMAC)
 252              && !EVP_MAC_is_a(EVP_MAC_get_ctx_mac(ctx->ctx_init),
 253                               OSSL_MAC_NAME_CMAC)) {
 254         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MAC);
 255         return 0;
 256     }
 257
 258     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE);
 259     if (p != NULL && strncasecmp("counter", p->data, p->data_size) == 0) {
 260         ctx->mode = COUNTER;
 261     } else if (p != NULL
 262                && strncasecmp("feedback", p->data, p->data_size) == 0) {
 263         ctx->mode = FEEDBACK;
 264     } else if (p != NULL) {
 265         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
 266         return 0;
 267     }
 268
 269     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY);
 270     if (p != NULL && !kbkdf_set_buffer(&ctx->ki, &ctx->ki_len, p))
 271         return 0;
 272
 273     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT);
 274     if (p != NULL && !kbkdf_set_buffer(&ctx->label, &ctx->label_len, p))
 275         return 0;
 276
 277     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO);
 278     if (p != NULL && !kbkdf_set_buffer(&ctx->context, &ctx->context_len, p))
 279         return 0;
 280
 281     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED);
 282     if (p != NULL && !kbkdf_set_buffer(&ctx->iv, &ctx->iv_len, p))
 283         return 0;
 284
 285     /* Set up digest context, if we can. */
 286     if (ctx->ctx_init != NULL && ctx->ki_len != 0) {
 287         mparams[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
 288                                                        ctx->ki, ctx->ki_len);
 289         mparams[1] = OSSL_PARAM_construct_end();
 290
 291         if (!EVP_MAC_set_ctx_params(ctx->ctx_init, mparams)
 292             || !EVP_MAC_init(ctx->ctx_init))
 293             return 0;
 294     }
 295
 296     return 1;
 297 }
 298
 299 static const OSSL_PARAM *kbkdf_settable_ctx_params(void)
 300 {
 301     static const OSSL_PARAM known_settable_ctx_params[] = {
 302         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
 303         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
 304         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 305         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
 306         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 307         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0),
 308         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),
 309         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
 310
 311         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 312         OSSL_PARAM_END,
 313     };
 314     return known_settable_ctx_params;
 315 }
 316
 317 static int kbkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 318 {
 319     OSSL_PARAM *p;
 320
 321     p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE);
 322     if (p == NULL)
 323         return -2;
 324
 325     /* KBKDF can produce results as large as you like. */
 326     return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 327 }
 328
 329 static const OSSL_PARAM *kbkdf_gettable_ctx_params(void)
 330 {
 331     static const OSSL_PARAM known_gettable_ctx_params[] =
 332         { OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL), OSSL_PARAM_END };
 333     return known_gettable_ctx_params;
 334 }
 335
 336 const OSSL_DISPATCH kdf_kbkdf_functions[] = {
 337     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kbkdf_new },
 338     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kbkdf_free },
 339     { OSSL_FUNC_KDF_RESET, (void(*)(void))kbkdf_reset },
 340     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kbkdf_derive },
 341     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 342       (void(*)(void))kbkdf_settable_ctx_params },
 343     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kbkdf_set_ctx_params },
 344     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 345       (void(*)(void))kbkdf_gettable_ctx_params },
 346     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kbkdf_get_ctx_params },
 347     { 0, NULL },
 348 };