/*

 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")

 *

 * SPDX-License-Identifier: MPL-2.0

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, you can obtain one at https://mozilla.org/MPL/2.0/.

 *

 * See the COPYRIGHT file distributed with this work for additional

 * information regarding copyright ownership.

 */

#include <stdbool.h>

#include <stdint.h>

#include <openssl/core_names.h>

#include <openssl/crypto.h>

#include <openssl/err.h>

#include <openssl/evp.h>

#include <openssl/provider.h>

#include <openssl/rand.h>

#include <openssl/ssl.h>

#include <isc/buffer.h>

#include <isc/crypto.h>

#include <isc/hmac.h>

#include <isc/log.h>

#include <isc/magic.h>

#include <isc/md.h>

#include <isc/mem.h>

#include <isc/ossl_wrap.h>

#include <isc/region.h>

#include <isc/safe.h>

#include <isc/util.h>

struct isc_hmac_key {

  uint32_t magic;

  uint32_t len;

  isc_mem_t *mctx;

  const OSSL_PARAM *params;

  uint8_t secret[];

};

constexpr uint32_t hmac_key_magic = ISC_MAGIC('H', 'M', 'A', 'C');

static OSSL_PROVIDER *base = NULL, *fips = NULL;

static EVP_MAC *evp_hmac = NULL;

static OSSL_PARAM md_to_hmac_params[ISC_MD_MAX][2] = {

  [ISC_MD_UNKNOWN] = { OSSL_PARAM_END },

  [ISC_MD_MD5] = {

    OSSL_PARAM_utf8_string(OSSL_MAC_PARAM_DIGEST, UNCONST("MD5"), sizeof("MD5") - 1),

    OSSL_PARAM_END,

  },

  [ISC_MD_SHA1] = {

    OSSL_PARAM_utf8_string(OSSL_MAC_PARAM_DIGEST, UNCONST("SHA1"), sizeof("SHA1") - 1),

    OSSL_PARAM_END,

  },

  [ISC_MD_SHA224] = {

    OSSL_PARAM_utf8_string(OSSL_MAC_PARAM_DIGEST, UNCONST("SHA2-224"), sizeof("SHA2-224") - 1),

    OSSL_PARAM_END,

  },

  [ISC_MD_SHA256] = {

    OSSL_PARAM_utf8_string(OSSL_MAC_PARAM_DIGEST, UNCONST("SHA2-256"), sizeof("SHA2-256") - 1),

    OSSL_PARAM_END,

  },

  [ISC_MD_SHA384] = {

    OSSL_PARAM_utf8_string(OSSL_MAC_PARAM_DIGEST, UNCONST("SHA2-384"), sizeof("SHA2-384") - 1),

    OSSL_PARAM_END,

  },

  [ISC_MD_SHA512] = {

    OSSL_PARAM_utf8_string(OSSL_MAC_PARAM_DIGEST, UNCONST("SHA2-512"), sizeof("SHA2-512") - 1),

    OSSL_PARAM_END,

  },

};

#define md_register_algorithm(alg)                                             \

  {                                                                      \

    REQUIRE(isc__crypto_md[ISC_MD_##alg] == NULL);                 \

    isc__crypto_md[ISC_MD_##alg] = EVP_MD_fetch(NULL, #alg, NULL); \

    if (isc__crypto_md[ISC_MD_##alg] == NULL) {                    \

      ERR_clear_error();                                     \

    }                                                              \

  }

static isc_result_t

register_algorithms(void) {

  if (!isc_crypto_fips_mode()) {

    md_register_algorithm(MD5);

  }

  md_register_algorithm(SHA1);

  md_register_algorithm(SHA224);

  md_register_algorithm(SHA256);

  md_register_algorithm(SHA384);

  md_register_algorithm(SHA512);

  /* We _must_ have HMAC */

  evp_hmac = EVP_MAC_fetch(NULL, "HMAC", NULL);

  if (evp_hmac == NULL) {

    ERR_clear_error();

    FATAL_ERROR("OpenSSL failed to find an HMAC implementation. "

          "Please make sure the default provider has an "

          "EVP_MAC-HMAC implementation");

  }

  return ISC_R_SUCCESS;

}

static void

unregister_algorithms(void) {

  for (size_t i = 0; i < ISC_MD_MAX; i++) {

    if (isc__crypto_md[i] != NULL) {

      EVP_MD_free(isc__crypto_md[i]);

      isc__crypto_md[i] = NULL;

    }

  }

  INSIST(evp_hmac != NULL);

  EVP_MAC_free(evp_hmac);

  evp_hmac = NULL;

}

#undef md_register_algorithm

/*

 * HMAC

 */

/*

 * Do not call EVP_Q_mac or HMAC (since it calls EVP_Q_mac internally)

 *

 * Each invocation of the EVP_Q_mac function causes an explicit fetch.

 */

isc_result_t

isc_hmac(isc_md_type_t type, const void *key, const size_t keylen,

   const unsigned char *buf, const size_t len, unsigned char *digest,

   unsigned int *digestlen) {

  EVP_MAC_CTX *ctx;

  size_t maclen;

  REQUIRE(type < ISC_MD_MAX);

  if (isc__crypto_md[type] == NULL) {

    return ISC_R_NOTIMPLEMENTED;

  }

  ctx = EVP_MAC_CTX_new(evp_hmac);

  RUNTIME_CHECK(ctx != NULL);

  if (EVP_MAC_init(ctx, key, keylen, md_to_hmac_params[type]) != 1) {

    goto fail;

  }

  if (EVP_MAC_update(ctx, buf, len) != 1) {

    goto fail;

  }

  maclen = *digestlen;

  if (EVP_MAC_final(ctx, digest, &maclen, maclen) != 1) {

    goto fail;

  }

  *digestlen = maclen;

  EVP_MAC_CTX_free(ctx);

  return ISC_R_SUCCESS;

fail:

  ERR_clear_error();

  EVP_MAC_CTX_free(ctx);

  return ISC_R_CRYPTOFAILURE;

}

/*

 * You do not need to process the key to fit the block size.

 *

 * https://github.com/openssl/openssl/blob/925e4fba1098036e8f8d22652cff6f64c5c7d571/crypto/hmac/hmac.c#L61-L80

 */

isc_result_t

isc_hmac_key_create(isc_md_type_t type, const void *secret, const size_t len,

        isc_mem_t *mctx, isc_hmac_key_t **keyp) {

  isc_hmac_key_t *key;

  uint8_t digest[ISC_MAX_MD_SIZE];

  unsigned int digest_len = sizeof(digest);

  size_t key_len;

  REQUIRE(keyp != NULL && *keyp == NULL);

  REQUIRE(type < ISC_MD_MAX);

  if (isc__crypto_md[type] == NULL) {

    return ISC_R_NOTIMPLEMENTED;

  }

  if (len > (size_t)EVP_MD_block_size(isc__crypto_md[type])) {

    RETERR(isc_md(type, secret, len, digest, &digest_len));

    secret = digest;

    key_len = digest_len;

  } else {

    key_len = len;

  }

  key = isc_mem_get(mctx, STRUCT_FLEX_SIZE(key, secret, key_len));

  *key = (isc_hmac_key_t){

    .magic = hmac_key_magic,

    .len = key_len,

    .params = md_to_hmac_params[type],

  };

  memmove(key->secret, secret, key_len);

  isc_mem_attach(mctx, &key->mctx);

  *keyp = key;

  return ISC_R_SUCCESS;

}

void

isc_hmac_key_destroy(isc_hmac_key_t **keyp) {

  isc_hmac_key_t *key;

  REQUIRE(keyp != NULL && *keyp != NULL);

  REQUIRE((*keyp)->magic == hmac_key_magic);

  key = *keyp;

  *keyp = NULL;

  key->magic = 0x00;

  isc_safe_memwipe(key->secret, key->len);

  isc_mem_putanddetach(&key->mctx, key,

           STRUCT_FLEX_SIZE(key, secret, key->len));

}

isc_region_t

isc_hmac_key_expose(isc_hmac_key_t *key) {

  REQUIRE(key != NULL && key->magic == hmac_key_magic);

  return (isc_region_t){ .base = key->secret, .length = key->len };

}

bool

isc_hmac_key_equal(isc_hmac_key_t *a, isc_hmac_key_t *b) {

  REQUIRE(a != NULL && a->magic == hmac_key_magic);

  REQUIRE(b != NULL && b->magic == hmac_key_magic);

  if (a->params != b->params) {

    return false;

  }

  if (a->len != b->len) {

    return false;

  }

  return isc_safe_memequal(a->secret, b->secret, a->len);

}

isc_hmac_t *

isc_hmac_new(void) {

  EVP_MAC_CTX *ctx = EVP_MAC_CTX_new(evp_hmac);

  RUNTIME_CHECK(ctx != NULL);

  return ctx;

}

void

isc_hmac_free(isc_hmac_t *hmac) {

  EVP_MAC_CTX_free(hmac);

}

isc_result_t

isc_hmac_init(isc_hmac_t *hmac, isc_hmac_key_t *key) {

  REQUIRE(key != NULL && key->magic == hmac_key_magic);

  REQUIRE(hmac != NULL);

  if (EVP_MAC_init(hmac, key->secret, key->len, key->params) != 1) {

    ERR_clear_error();

    return ISC_R_CRYPTOFAILURE;

  }

  return ISC_R_SUCCESS;

}

isc_result_t

isc_hmac_update(isc_hmac_t *hmac, const unsigned char *buf, const size_t len) {

  REQUIRE(hmac != NULL);

  if (buf == NULL || len == 0) {

    return ISC_R_SUCCESS;

  }

  if (EVP_MAC_update(hmac, buf, len) != 1) {

    ERR_clear_error();

    return ISC_R_CRYPTOFAILURE;

  }

  return ISC_R_SUCCESS;

}

isc_result_t

isc_hmac_final(isc_hmac_t *hmac, isc_buffer_t *out) {

  size_t len;

  REQUIRE(hmac != NULL);

  len = isc_buffer_availablelength(out);

  if (len < EVP_MAC_CTX_get_mac_size(hmac)) {

    return ISC_R_NOSPACE;

  }

  if (EVP_MAC_final(hmac, isc_buffer_used(out), &len, len) != 1) {

    ERR_clear_error();

    return ISC_R_CRYPTOFAILURE;

  }

  isc_buffer_add(out, len);

  return ISC_R_SUCCESS;

}

bool

isc_crypto_fips_mode(void) {

  return EVP_default_properties_is_fips_enabled(NULL) != 0;

}

isc_result_t

isc_crypto_fips_enable(void) {

  if (isc_crypto_fips_mode()) {

    return ISC_R_SUCCESS;

  }

  INSIST(fips == NULL);

  fips = OSSL_PROVIDER_load(NULL, "fips");

  if (fips == NULL) {

    return isc_ossl_wrap_logged_toresult(

      ISC_LOGCATEGORY_GENERAL, ISC_LOGMODULE_CRYPTO,

      "OSSL_PROVIDER_load", ISC_R_CRYPTOFAILURE);

  }

  INSIST(base == NULL);

  base = OSSL_PROVIDER_load(NULL, "base");

  if (base == NULL) {

    OSSL_PROVIDER_unload(fips);

    return isc_ossl_wrap_logged_toresult(

      ISC_LOGCATEGORY_GENERAL, ISC_LOGMODULE_CRYPTO,

      "OSS_PROVIDER_load", ISC_R_CRYPTOFAILURE);

  }

  if (EVP_default_properties_enable_fips(NULL, 1) == 0) {

    return isc_ossl_wrap_logged_toresult(

      ISC_LOGCATEGORY_GENERAL, ISC_LOGMODULE_CRYPTO,

      "EVP_default_properties_enable_fips",

      ISC_R_CRYPTOFAILURE);

  }

  unregister_algorithms();

  register_algorithms();

  return ISC_R_SUCCESS;

}

/*

 * OPENSSL_cleanup() in OpenSSL 4 doesn't free the memory, which is not

 * compatible with BIND 9's memory leak detection code, that is why the memory

 * tracking has been disabled in this module, and this function is a no-op.

 * This can be cleaned up once OpenSSL 1.1.x support is removed.

 *

 * See https://github.com/openssl/openssl/pull/29721

 */

void

isc__crypto_setdestroycheck(bool check) {

  UNUSED(check);

}

void

isc__crypto_initialize(void) {

  /*

   * We call OPENSSL_cleanup() manually, in a correct order, thus disable

   * the automatic atexit() handler.

   */

  uint64_t opts = OPENSSL_INIT_LOAD_CONFIG | OPENSSL_INIT_NO_ATEXIT;

  RUNTIME_CHECK(OPENSSL_init_ssl(opts, NULL) == 1);

  register_algorithms();

#if defined(ENABLE_FIPS_MODE)

  if (isc_crypto_fips_enable() != ISC_R_SUCCESS) {

    ERR_clear_error();

    FATAL_ERROR("Failed to toggle FIPS mode but is "

          "required for this build");

  }

#endif

  /* Protect ourselves against unseeded PRNG */

  if (RAND_status() != 1) {

    isc_ossl_wrap_logged_toresult(

      ISC_LOGCATEGORY_GENERAL, ISC_LOGMODULE_CRYPTO,

      "RAND_status", ISC_R_CRYPTOFAILURE);

    FATAL_ERROR("OpenSSL pseudorandom number generator "

          "cannot be initialized (see the `PRNG not "

          "seeded' message in the OpenSSL FAQ)");

  }

}

void

isc__crypto_shutdown(void) {

  unregister_algorithms();

  if (base != NULL) {

    OSSL_PROVIDER_unload(base);

  }

  if (fips != NULL) {

    OSSL_PROVIDER_unload(fips);

  }

  OPENSSL_cleanup();

}