providers/implementations/kdfs/kbkdf.c

   1 /*
   2  * Copyright 2019-2020 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 "internal/endian.h"
  41 #include "prov/implementations.h"
  42 #include "prov/provider_ctx.h"
  43 #include "prov/provider_util.h"
  44 #include "prov/providercommon.h"
  45 #include "prov/providercommonerr.h"
  46
  47 #include "e_os.h"
  48
  49 #define MIN(a, b) ((a) < (b)) ? (a) : (b)
  50
  51 typedef enum {
  52     COUNTER = 0,
  53     FEEDBACK
  54 } kbkdf_mode;
  55
  56 /* Our context structure. */
  57 typedef struct {
  58     void *provctx;
  59     kbkdf_mode mode;
  60     EVP_MAC_CTX *ctx_init;
  61
  62     /* Names are lowercased versions of those found in SP800-108. */
  63     unsigned char *ki;
  64     size_t ki_len;
  65     unsigned char *label;
  66     size_t label_len;
  67     unsigned char *context;
  68     size_t context_len;
  69     unsigned char *iv;
  70     size_t iv_len;
  71 } KBKDF;
  72
  73 /* Definitions needed for typechecking. */
  74 static OSSL_FUNC_kdf_newctx_fn kbkdf_new;
  75 static OSSL_FUNC_kdf_freectx_fn kbkdf_free;
  76 static OSSL_FUNC_kdf_reset_fn kbkdf_reset;
  77 static OSSL_FUNC_kdf_derive_fn kbkdf_derive;
  78 static OSSL_FUNC_kdf_settable_ctx_params_fn kbkdf_settable_ctx_params;
  79 static OSSL_FUNC_kdf_set_ctx_params_fn kbkdf_set_ctx_params;
  80 static OSSL_FUNC_kdf_gettable_ctx_params_fn kbkdf_gettable_ctx_params;
  81 static OSSL_FUNC_kdf_get_ctx_params_fn kbkdf_get_ctx_params;
  82
  83 /* Not all platforms have htobe32(). */
  84 static uint32_t be32(uint32_t host)
  85 {
  86     uint32_t big = 0;
  87     DECLARE_IS_ENDIAN;
  88
  89     if (!IS_LITTLE_ENDIAN)
  90         return host;
  91
  92     big |= (host & 0xff000000) >> 24;
  93     big |= (host & 0x00ff0000) >> 8;
  94     big |= (host & 0x0000ff00) << 8;
  95     big |= (host & 0x000000ff) << 24;
  96     return big;
  97 }
  98
  99 static void *kbkdf_new(void *provctx)
 100 {
 101     KBKDF *ctx;
 102
 103     if (!ossl_prov_is_running())
 104         return NULL;
 105
 106     ctx = OPENSSL_zalloc(sizeof(*ctx));
 107     if (ctx == NULL) {
 108         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 109         return NULL;
 110     }
 111
 112     ctx->provctx = provctx;
 113     return ctx;
 114 }
 115
 116 static void kbkdf_free(void *vctx)
 117 {
 118     KBKDF *ctx = (KBKDF *)vctx;
 119
 120     if (ctx != NULL) {
 121         kbkdf_reset(ctx);
 122         OPENSSL_free(ctx);
 123     }
 124 }
 125
 126 static void kbkdf_reset(void *vctx)
 127 {
 128     KBKDF *ctx = (KBKDF *)vctx;
 129     void *provctx = ctx->provctx;
 130
 131     EVP_MAC_CTX_free(ctx->ctx_init);
 132     OPENSSL_clear_free(ctx->context, ctx->context_len);
 133     OPENSSL_clear_free(ctx->label, ctx->label_len);
 134     OPENSSL_clear_free(ctx->ki, ctx->ki_len);
 135     OPENSSL_clear_free(ctx->iv, ctx->iv_len);
 136     memset(ctx, 0, sizeof(*ctx));
 137     ctx->provctx = provctx;
 138 }
 139
 140 /* SP800-108 section 5.1 or section 5.2 depending on mode. */
 141 static int derive(EVP_MAC_CTX *ctx_init, kbkdf_mode mode, unsigned char *iv,
 142                   size_t iv_len, unsigned char *label, size_t label_len,
 143                   unsigned char *context, size_t context_len,
 144                   unsigned char *k_i, size_t h, uint32_t l, unsigned char *ko,
 145                   size_t ko_len)
 146 {
 147     int ret = 0;
 148     EVP_MAC_CTX *ctx = NULL;
 149     size_t written = 0, to_write, k_i_len = iv_len;
 150     const unsigned char zero = 0;
 151     uint32_t counter, i;
 152
 153     /* Setup K(0) for feedback mode. */
 154     if (iv_len > 0)
 155         memcpy(k_i, iv, iv_len);
 156
 157     for (counter = 1; written < ko_len; counter++) {
 158         i = be32(counter);
 159
 160         ctx = EVP_MAC_CTX_dup(ctx_init);
 161         if (ctx == NULL)
 162             goto done;
 163
 164         /* Perform feedback, if appropriate. */
 165         if (mode == FEEDBACK && !EVP_MAC_update(ctx, k_i, k_i_len))
 166             goto done;
 167
 168         if (!EVP_MAC_update(ctx, (unsigned char *)&i, 4)
 169             || !EVP_MAC_update(ctx, label, label_len)
 170             || !EVP_MAC_update(ctx, &zero, 1)
 171             || !EVP_MAC_update(ctx, context, context_len)
 172             || !EVP_MAC_update(ctx, (unsigned char *)&l, 4)
 173             || !EVP_MAC_final(ctx, k_i, NULL, h))
 174             goto done;
 175
 176         to_write = ko_len - written;
 177         memcpy(ko + written, k_i, MIN(to_write, h));
 178         written += h;
 179
 180         k_i_len = h;
 181         EVP_MAC_CTX_free(ctx);
 182         ctx = NULL;
 183     }
 184
 185     ret = 1;
 186 done:
 187     EVP_MAC_CTX_free(ctx);
 188     return ret;
 189 }
 190
 191 static int kbkdf_derive(void *vctx, unsigned char *key, size_t keylen)
 192 {
 193     KBKDF *ctx = (KBKDF *)vctx;
 194     int ret = 0;
 195     unsigned char *k_i = NULL;
 196     uint32_t l = be32(keylen * 8);
 197     size_t h = 0;
 198
 199     if (!ossl_prov_is_running())
 200         return 0;
 201
 202     /* label, context, and iv are permitted to be empty.  Check everything
 203      * else. */
 204     if (ctx->ctx_init == NULL) {
 205         if (ctx->ki_len == 0 || ctx->ki == NULL) {
 206             ERR_raise(ERR_LIB_PROV, PROV_R_NO_KEY_SET);
 207             return 0;
 208         }
 209         /* Could either be missing MAC or missing message digest or missing
 210          * cipher - arbitrarily, I pick this one. */
 211         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MAC);
 212         return 0;
 213     }
 214
 215     /* Fail if the output length is zero */
 216     if (keylen == 0) {
 217         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
 218         return 0;
 219     }
 220
 221     h = EVP_MAC_size(ctx->ctx_init);
 222     if (h == 0)
 223         goto done;
 224     if (ctx->iv_len != 0 && ctx->iv_len != h) {
 225         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_SEED_LENGTH);
 226         goto done;
 227     }
 228
 229     k_i = OPENSSL_zalloc(h);
 230     if (k_i == NULL)
 231         goto done;
 232
 233     ret = derive(ctx->ctx_init, ctx->mode, ctx->iv, ctx->iv_len, ctx->label,
 234                  ctx->label_len, ctx->context, ctx->context_len, k_i, h, l,
 235                  key, keylen);
 236 done:
 237     if (ret != 1)
 238         OPENSSL_cleanse(key, keylen);
 239     OPENSSL_clear_free(k_i, h);
 240     return ret;
 241 }
 242
 243 static int kbkdf_set_buffer(unsigned char **out, size_t *out_len,
 244                             const OSSL_PARAM *p)
 245 {
 246     if (p->data == NULL || p->data_size == 0)
 247         return 1;
 248
 249     OPENSSL_clear_free(*out, *out_len);
 250     *out = NULL;
 251     return OSSL_PARAM_get_octet_string(p, (void **)out, 0, out_len);
 252 }
 253
 254 static int kbkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 255 {
 256     KBKDF *ctx = (KBKDF *)vctx;
 257     OSSL_LIB_CTX *libctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
 258     const OSSL_PARAM *p;
 259     OSSL_PARAM mparams[2];
 260
 261     if (!ossl_prov_macctx_load_from_params(&ctx->ctx_init, params, NULL,
 262                                            NULL, NULL, libctx))
 263         return 0;
 264     else if (ctx->ctx_init != NULL
 265              && !EVP_MAC_is_a(EVP_MAC_CTX_mac(ctx->ctx_init),
 266                               OSSL_MAC_NAME_HMAC)
 267              && !EVP_MAC_is_a(EVP_MAC_CTX_mac(ctx->ctx_init),
 268                               OSSL_MAC_NAME_CMAC)) {
 269         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MAC);
 270         return 0;
 271     }
 272
 273     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE);
 274     if (p != NULL && strncasecmp("counter", p->data, p->data_size) == 0) {
 275         ctx->mode = COUNTER;
 276     } else if (p != NULL
 277                && strncasecmp("feedback", p->data, p->data_size) == 0) {
 278         ctx->mode = FEEDBACK;
 279     } else if (p != NULL) {
 280         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
 281         return 0;
 282     }
 283
 284     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY);
 285     if (p != NULL && !kbkdf_set_buffer(&ctx->ki, &ctx->ki_len, p))
 286         return 0;
 287
 288     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT);
 289     if (p != NULL && !kbkdf_set_buffer(&ctx->label, &ctx->label_len, p))
 290         return 0;
 291
 292     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO);
 293     if (p != NULL && !kbkdf_set_buffer(&ctx->context, &ctx->context_len, p))
 294         return 0;
 295
 296     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED);
 297     if (p != NULL && !kbkdf_set_buffer(&ctx->iv, &ctx->iv_len, p))
 298         return 0;
 299
 300     /* Set up digest context, if we can. */
 301     if (ctx->ctx_init != NULL && ctx->ki_len != 0) {
 302         mparams[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
 303                                                        ctx->ki, ctx->ki_len);
 304         mparams[1] = OSSL_PARAM_construct_end();
 305
 306         if (!EVP_MAC_CTX_set_params(ctx->ctx_init, mparams)
 307             || !EVP_MAC_init(ctx->ctx_init))
 308             return 0;
 309     }
 310
 311     return 1;
 312 }
 313
 314 static const OSSL_PARAM *kbkdf_settable_ctx_params(ossl_unused void *provctx)
 315 {
 316     static const OSSL_PARAM known_settable_ctx_params[] = {
 317         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
 318         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
 319         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 320         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
 321         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 322         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0),
 323         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),
 324         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
 325
 326         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 327         OSSL_PARAM_END,
 328     };
 329     return known_settable_ctx_params;
 330 }
 331
 332 static int kbkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 333 {
 334     OSSL_PARAM *p;
 335
 336     p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE);
 337     if (p == NULL)
 338         return -2;
 339
 340     /* KBKDF can produce results as large as you like. */
 341     return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 342 }
 343
 344 static const OSSL_PARAM *kbkdf_gettable_ctx_params(ossl_unused void *provctx)
 345 {
 346     static const OSSL_PARAM known_gettable_ctx_params[] =
 347         { OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL), OSSL_PARAM_END };
 348     return known_gettable_ctx_params;
 349 }
 350
 351 const OSSL_DISPATCH ossl_kdf_kbkdf_functions[] = {
 352     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kbkdf_new },
 353     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kbkdf_free },
 354     { OSSL_FUNC_KDF_RESET, (void(*)(void))kbkdf_reset },
 355     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kbkdf_derive },
 356     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 357       (void(*)(void))kbkdf_settable_ctx_params },
 358     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kbkdf_set_ctx_params },
 359     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 360       (void(*)(void))kbkdf_gettable_ctx_params },
 361     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kbkdf_get_ctx_params },
 362     { 0, NULL },
 363 };