text: /*
   * Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
   * Copyright 2019 Red Hat, Inc.
   *
   * Licensed under the Apache License 2.0 (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  /*
   * This implements https://csrc.nist.gov/publications/detail/sp/800-108/final
   * section 5.1 ("counter mode") and section 5.2 ("feedback mode") in both HMAC
   * and CMAC.  That document does not name the KDFs it defines; the name is
   * derived from
   * https://csrc.nist.gov/Projects/Cryptographic-Algorithm-Validation-Program/Key-Derivation
   *
   * Note that section 5.3 ("double-pipeline mode") is not implemented, though
   * it would be possible to do so in the future.
   *
   * These versions all assume the counter is used.  It would be relatively
   * straightforward to expose a configuration handle should the need arise.
   *
   * Variable names attempt to match those of SP800-108.
   */
  
  #include <stdarg.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include <openssl/core_names.h>
  #include <openssl/evp.h>
  #include <openssl/hmac.h>
  #include <openssl/kdf.h>
  #include <openssl/params.h>
  #include <openssl/proverr.h>
  
  #include "internal/cryptlib.h"
  #include "crypto/evp.h"
  #include "internal/numbers.h"
  #include "internal/endian.h"
  #include "prov/implementations.h"
  #include "prov/provider_ctx.h"
  #include "prov/provider_util.h"
  #include "prov/providercommon.h"
  
  #include "e_os.h"
  
  #define MIN(a, b) ((a) < (b)) ? (a) : (b)
  
  typedef enum {
      COUNTER = 0,
      FEEDBACK
  } kbkdf_mode;
  
  /* Our context structure. */
  typedef struct {
      void *provctx;
      kbkdf_mode mode;
      EVP_MAC_CTX *ctx_init;
  
      /* Names are lowercased versions of those found in SP800-108. */
      int r;
      unsigned char *ki;
      size_t ki_len;
      unsigned char *label;
      size_t label_len;
      unsigned char *context;
      size_t context_len;
      unsigned char *iv;
      size_t iv_len;
      int use_l;
      int use_separator;
  } KBKDF;
  
  /* Definitions needed for typechecking. */
  static OSSL_FUNC_kdf_newctx_fn kbkdf_new;
  static OSSL_FUNC_kdf_freectx_fn kbkdf_free;
  static OSSL_FUNC_kdf_reset_fn kbkdf_reset;
  static OSSL_FUNC_kdf_derive_fn kbkdf_derive;
  static OSSL_FUNC_kdf_settable_ctx_params_fn kbkdf_settable_ctx_params;
  static OSSL_FUNC_kdf_set_ctx_params_fn kbkdf_set_ctx_params;
  static OSSL_FUNC_kdf_gettable_ctx_params_fn kbkdf_gettable_ctx_params;
  static OSSL_FUNC_kdf_get_ctx_params_fn kbkdf_get_ctx_params;
  
  /* Not all platforms have htobe32(). */
  static uint32_t be32(uint32_t host)
  {
      uint32_t big = 0;
      DECLARE_IS_ENDIAN;
  
      if (!IS_LITTLE_ENDIAN)
          return host;
  
      big |= (host & 0xff000000) >> 24;
      big |= (host & 0x00ff0000) >> 8;
      big |= (host & 0x0000ff00) << 8;
      big |= (host & 0x000000ff) << 24;
      return big;
  }
  
  static void init(KBKDF *ctx)
  {
      ctx->r = 32;
      ctx->use_l = 1;
      ctx->use_separator = 1;
  }
  
  static void *kbkdf_new(void *provctx)
  {
      KBKDF *ctx;
  
      if (!ossl_prov_is_running())
          return NULL;
  
      ctx = OPENSSL_zalloc(sizeof(*ctx));
      if (ctx == NULL) {
          ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
          return NULL;
      }
  
      ctx->provctx = provctx;
      init(ctx);
      return ctx;
  }
  
  static void kbkdf_free(void *vctx)
  {
      KBKDF *ctx = (KBKDF *)vctx;
  
      if (ctx != NULL) {
          kbkdf_reset(ctx);
          OPENSSL_free(ctx);
      }
  }
  
  static void kbkdf_reset(void *vctx)
  {
      KBKDF *ctx = (KBKDF *)vctx;
      void *provctx = ctx->provctx;
  
      EVP_MAC_CTX_free(ctx->ctx_init);
      OPENSSL_clear_free(ctx->context, ctx->context_len);
      OPENSSL_clear_free(ctx->label, ctx->label_len);
      OPENSSL_clear_free(ctx->ki, ctx->ki_len);
      OPENSSL_clear_free(ctx->iv, ctx->iv_len);
      memset(ctx, 0, sizeof(*ctx));
      ctx->provctx = provctx;
      init(ctx);
  }
  
  /* SP800-108 section 5.1 or section 5.2 depending on mode. */
  static int derive(EVP_MAC_CTX *ctx_init, kbkdf_mode mode, unsigned char *iv,
                    size_t iv_len, unsigned char *label, size_t label_len,
                    unsigned char *context, size_t context_len,
                    unsigned char *k_i, size_t h, uint32_t l, int has_separator,
                    unsigned char *ko, size_t ko_len, int r)
  {
      int ret = 0;
      EVP_MAC_CTX *ctx = NULL;
      size_t written = 0, to_write, k_i_len = iv_len;
      const unsigned char zero = 0;
      uint32_t counter, i;
      /*
       * From SP800-108:
       * The fixed input data is a concatenation of a Label,
       * a separation indicator 0x00, the Context, and L.
       * One or more of these fixed input data fields may be omitted.
       *
       * has_separator == 0 means that the separator is omitted.
       * Passing a value of l == 0 means that L is omitted.
       * The Context and L are omitted automatically if a NULL buffer is passed.
       */
      int has_l = (l != 0);
  
      /* Setup K(0) for feedback mode. */
      if (iv_len > 0)
          memcpy(k_i, iv, iv_len);
  
      for (counter = 1; written < ko_len; counter++) {
          i = be32(counter);
  
          ctx = EVP_MAC_CTX_dup(ctx_init);
          if (ctx == NULL)
              goto done;
  
          /* Perform feedback, if appropriate. */
          if (mode == FEEDBACK && !EVP_MAC_update(ctx, k_i, k_i_len))
              goto done;
  
          if (!EVP_MAC_update(ctx, 4 - (r / 8) + (unsigned char *)&i, r / 8)
              || !EVP_MAC_update(ctx, label, label_len)
              || (has_separator && !EVP_MAC_update(ctx, &zero, 1))
              || !EVP_MAC_update(ctx, context, context_len)
              || (has_l && !EVP_MAC_update(ctx, (unsigned char *)&l, 4))
              || !EVP_MAC_final(ctx, k_i, NULL, h))
              goto done;
  
          to_write = ko_len - written;
          memcpy(ko + written, k_i, MIN(to_write, h));
          written += h;
  
          k_i_len = h;
          EVP_MAC_CTX_free(ctx);
          ctx = NULL;
      }
  
      ret = 1;
  done:
      EVP_MAC_CTX_free(ctx);
      return ret;
  }
  
  static int kbkdf_derive(void *vctx, unsigned char *key, size_t keylen,
                          const OSSL_PARAM params[])
  {
      KBKDF *ctx = (KBKDF *)vctx;
      int ret = 0;
      unsigned char *k_i = NULL;
      uint32_t l = 0;
      size_t h = 0;
      uint64_t counter_max;
  
      if (!ossl_prov_is_running() || !kbkdf_set_ctx_params(ctx, params))
          return 0;
  
      /* label, context, and iv are permitted to be empty.  Check everything
       * else. */
      if (ctx->ctx_init == NULL) {
          if (ctx->ki_len == 0 || ctx->ki == NULL) {
              ERR_raise(ERR_LIB_PROV, PROV_R_NO_KEY_SET);
              return 0;
          }
          /* Could either be missing MAC or missing message digest or missing
           * cipher - arbitrarily, I pick this one. */
          ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MAC);
          return 0;
      }
  
      /* Fail if the output length is zero */
      if (keylen == 0) {
          ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
          return 0;
      }
  
      h = EVP_MAC_CTX_get_mac_size(ctx->ctx_init);
      if (h == 0)
          goto done;
      if (ctx->iv_len != 0 && ctx->iv_len != h) {
          ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_SEED_LENGTH);
          goto done;
      }
  
      if (ctx->mode == COUNTER) {
          /* Fail if keylen is too large for r */
          counter_max = (uint64_t)1 << (uint64_t)ctx->r;
          if ((uint64_t)(keylen / h) >= counter_max) {
              ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
              goto done;
          }
      }
  
      if (ctx->use_l != 0)
          l = be32(keylen * 8);
  
      k_i = OPENSSL_zalloc(h);
      if (k_i == NULL)
          goto done;
  
      ret = derive(ctx->ctx_init, ctx->mode, ctx->iv, ctx->iv_len, ctx->label,
                   ctx->label_len, ctx->context, ctx->context_len, k_i, h, l,
                   ctx->use_separator, key, keylen, ctx->r);
  done:
      if (ret != 1)
          OPENSSL_cleanse(key, keylen);
      OPENSSL_clear_free(k_i, h);
      return ret;
  }
  
  static int kbkdf_set_buffer(unsigned char **out, size_t *out_len,
                              const OSSL_PARAM *p)
  {
      if (p->data == NULL || p->data_size == 0)
          return 1;
  
      OPENSSL_clear_free(*out, *out_len);
      *out = NULL;
      return OSSL_PARAM_get_octet_string(p, (void **)out, 0, out_len);
  }
  
  static int kbkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
  {
      KBKDF *ctx = (KBKDF *)vctx;
      OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
      const OSSL_PARAM *p;
  
      if (params == NULL)
          return 1;
  
      if (!ossl_prov_macctx_load_from_params(&ctx->ctx_init, params, NULL,
                                             NULL, NULL, libctx))
          return 0;
      else if (ctx->ctx_init != NULL
               && !EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init),
                                OSSL_MAC_NAME_HMAC)
               && !EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init),
                                OSSL_MAC_NAME_CMAC)) {
          ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MAC);
          return 0;
      }
  
      p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE);
      if (p != NULL && strncasecmp("counter", p->data, p->data_size) == 0) {
          ctx->mode = COUNTER;
      } else if (p != NULL
                 && strncasecmp("feedback", p->data, p->data_size) == 0) {
          ctx->mode = FEEDBACK;
      } else if (p != NULL) {
          ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
          return 0;
      }
  
      p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY);
      if (p != NULL && !kbkdf_set_buffer(&ctx->ki, &ctx->ki_len, p))
          return 0;
  
      p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT);
      if (p != NULL && !kbkdf_set_buffer(&ctx->label, &ctx->label_len, p))
          return 0;
  
      p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO);
      if (p != NULL && !kbkdf_set_buffer(&ctx->context, &ctx->context_len, p))
          return 0;
  
      p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED);
      if (p != NULL && !kbkdf_set_buffer(&ctx->iv, &ctx->iv_len, p))
          return 0;
  
      p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_L);
      if (p != NULL && !OSSL_PARAM_get_int(p, &ctx->use_l))
          return 0;
  
      p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_R);
      if (p != NULL) {
          int new_r = 0;
  
          if (!OSSL_PARAM_get_int(p, &new_r))
              return 0;
          if (new_r != 8 && new_r != 16 && new_r != 24 && new_r != 32)
              return 0;
          ctx->r = new_r;
      }
  
      p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR);
      if (p != NULL && !OSSL_PARAM_get_int(p, &ctx->use_separator))
          return 0;
  
      /* Set up digest context, if we can. */
      if (ctx->ctx_init != NULL && ctx->ki_len != 0
              && !EVP_MAC_init(ctx->ctx_init, ctx->ki, ctx->ki_len, NULL))
              return 0;
      return 1;
  }
  
  static const OSSL_PARAM *kbkdf_settable_ctx_params(ossl_unused void *ctx,
                                                     ossl_unused void *provctx)
  {
      static const OSSL_PARAM known_settable_ctx_params[] = {
          OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
          OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
          OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
          OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
          OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
          OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0),
          OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),
          OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
          OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
          OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_L, NULL),
          OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR, NULL),
          OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_R, NULL),
          OSSL_PARAM_END,
      };
      return known_settable_ctx_params;
  }
  
  static int kbkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
  {
      OSSL_PARAM *p;
  
      p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE);
      if (p == NULL)
          return -2;
  
      /* KBKDF can produce results as large as you like. */
      return OSSL_PARAM_set_size_t(p, SIZE_MAX);
  }
  
  static const OSSL_PARAM *kbkdf_gettable_ctx_params(ossl_unused void *ctx,
                                                     ossl_unused void *provctx)
  {
      static const OSSL_PARAM known_gettable_ctx_params[] =
          { OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL), OSSL_PARAM_END };
      return known_gettable_ctx_params;
  }
  
  const OSSL_DISPATCH ossl_kdf_kbkdf_functions[] = {
      { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kbkdf_new },
      { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kbkdf_free },
      { OSSL_FUNC_KDF_RESET, (void(*)(void))kbkdf_reset },
      { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kbkdf_derive },
      { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
        (void(*)(void))kbkdf_settable_ctx_params },
      { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kbkdf_set_ctx_params },
      { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
        (void(*)(void))kbkdf_gettable_ctx_params },
      { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kbkdf_get_ctx_params },
      { 0, NULL },
  };
  