// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   * Cryptographic API.
   *
   * Null algorithms, aka Much Ado About Nothing.
   *
   * These are needed for IPsec, and may be useful in general for
   * testing & debugging.

   *

   * The null cipher is compliant with RFC2410.
   *
   * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>

   */

  #include <crypto/null.h>

  #include <crypto/internal/hash.h>

  #include <crypto/internal/skcipher.h>

  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/mm.h>

  #include <linux/string.h>

  static DEFINE_MUTEX(crypto_default_null_skcipher_lock);

  static struct crypto_sync_skcipher *crypto_default_null_skcipher;

  static int crypto_default_null_skcipher_refcnt;

  static int null_compress(struct crypto_tfm *tfm, const u8 *src,
  			 unsigned int slen, u8 *dst, unsigned int *dlen)

  {
  	if (slen > *dlen)
  		return -EINVAL;
  	memcpy(dst, src, slen);
  	*dlen = slen;
  	return 0;
  }

  static int null_init(struct shash_desc *desc)
  {
  	return 0;
  }

  static int null_update(struct shash_desc *desc, const u8 *data,
  		       unsigned int len)
  {
  	return 0;
  }

  static int null_final(struct shash_desc *desc, u8 *out)
  {
  	return 0;
  }
  
  static int null_digest(struct shash_desc *desc, const u8 *data,
  		       unsigned int len, u8 *out)
  {
  	return 0;
  }
  
  static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
  			    unsigned int keylen)
  { return 0; }

  static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
  				unsigned int keylen)
  { return 0; }

  static int null_setkey(struct crypto_tfm *tfm, const u8 *key,

  		       unsigned int keylen)

  { return 0; }

  static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)

  {
  	memcpy(dst, src, NULL_BLOCK_SIZE);
  }

  static int null_skcipher_crypt(struct skcipher_request *req)

  {

  	struct skcipher_walk walk;

  	int err;

  	err = skcipher_walk_virt(&walk, req, false);

  
  	while (walk.nbytes) {
  		if (walk.src.virt.addr != walk.dst.virt.addr)
  			memcpy(walk.dst.virt.addr, walk.src.virt.addr,
  			       walk.nbytes);

  		err = skcipher_walk_done(&walk, 0);

  	}
  
  	return err;
  }

  static struct shash_alg digest_null = {
  	.digestsize		=	NULL_DIGEST_SIZE,
  	.setkey   		=	null_hash_setkey,
  	.init   		=	null_init,
  	.update 		=	null_update,
  	.finup 			=	null_digest,
  	.digest 		=	null_digest,
  	.final  		=	null_final,
  	.base			=	{
  		.cra_name		=	"digest_null",

  		.cra_driver_name	=	"digest_null-generic",

  		.cra_blocksize		=	NULL_BLOCK_SIZE,
  		.cra_module		=	THIS_MODULE,
  	}

  };

  static struct skcipher_alg skcipher_null = {
  	.base.cra_name		=	"ecb(cipher_null)",
  	.base.cra_driver_name	=	"ecb-cipher_null",
  	.base.cra_priority	=	100,
  	.base.cra_blocksize	=	NULL_BLOCK_SIZE,
  	.base.cra_ctxsize	=	0,
  	.base.cra_module	=	THIS_MODULE,
  	.min_keysize		=	NULL_KEY_SIZE,
  	.max_keysize		=	NULL_KEY_SIZE,
  	.ivsize			=	NULL_IV_SIZE,
  	.setkey			=	null_skcipher_setkey,
  	.encrypt		=	null_skcipher_crypt,
  	.decrypt		=	null_skcipher_crypt,
  };
  
  static struct crypto_alg null_algs[] = { {

  	.cra_name		=	"cipher_null",

  	.cra_driver_name	=	"cipher_null-generic",

  	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
  	.cra_blocksize		=	NULL_BLOCK_SIZE,
  	.cra_ctxsize		=	0,
  	.cra_module		=	THIS_MODULE,

  	.cra_u			=	{ .cipher = {
  	.cia_min_keysize	=	NULL_KEY_SIZE,
  	.cia_max_keysize	=	NULL_KEY_SIZE,
  	.cia_setkey		= 	null_setkey,

  	.cia_encrypt		=	null_crypt,
  	.cia_decrypt		=	null_crypt } }

  }, {

  	.cra_name		=	"compress_null",

  	.cra_driver_name	=	"compress_null-generic",

  	.cra_flags		=	CRYPTO_ALG_TYPE_COMPRESS,
  	.cra_blocksize		=	NULL_BLOCK_SIZE,
  	.cra_ctxsize		=	0,
  	.cra_module		=	THIS_MODULE,
  	.cra_u			=	{ .compress = {
  	.coa_compress		=	null_compress,
  	.coa_decompress		=	null_compress } }
  } };

  MODULE_ALIAS_CRYPTO("compress_null");
  MODULE_ALIAS_CRYPTO("digest_null");
  MODULE_ALIAS_CRYPTO("cipher_null");

  struct crypto_sync_skcipher *crypto_get_default_null_skcipher(void)

  {

  	struct crypto_sync_skcipher *tfm;

  
  	mutex_lock(&crypto_default_null_skcipher_lock);
  	tfm = crypto_default_null_skcipher;
  
  	if (!tfm) {

  		tfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0);

  		if (IS_ERR(tfm))
  			goto unlock;
  
  		crypto_default_null_skcipher = tfm;
  	}
  
  	crypto_default_null_skcipher_refcnt++;
  
  unlock:
  	mutex_unlock(&crypto_default_null_skcipher_lock);
  
  	return tfm;
  }
  EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher);
  
  void crypto_put_default_null_skcipher(void)
  {
  	mutex_lock(&crypto_default_null_skcipher_lock);
  	if (!--crypto_default_null_skcipher_refcnt) {

  		crypto_free_sync_skcipher(crypto_default_null_skcipher);

  		crypto_default_null_skcipher = NULL;
  	}
  	mutex_unlock(&crypto_default_null_skcipher_lock);
  }
  EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);

  static int __init crypto_null_mod_init(void)

  {
  	int ret = 0;

  	ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));

  	if (ret < 0)
  		goto out;

  	ret = crypto_register_shash(&digest_null);

  	if (ret < 0)

  		goto out_unregister_algs;

  	ret = crypto_register_skcipher(&skcipher_null);
  	if (ret < 0)
  		goto out_unregister_shash;

  	return 0;

  out_unregister_shash:
  	crypto_unregister_shash(&digest_null);

  out_unregister_algs:
  	crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));

  out:

  	return ret;
  }

  static void __exit crypto_null_mod_fini(void)

  {

  	crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));

  	crypto_unregister_shash(&digest_null);
  	crypto_unregister_skcipher(&skcipher_null);

  }

  subsys_initcall(crypto_null_mod_init);

  module_exit(crypto_null_mod_fini);

  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Null Cryptographic Algorithms");