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

  /*
   * CBC: Cipher Block Chaining mode
   *

   * Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au>

   */

  #include <crypto/algapi.h>

  #include <crypto/cbc.h>

  #include <crypto/internal/skcipher.h>

  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/kernel.h>

  #include <linux/log2.h>

  #include <linux/module.h>

  static inline void crypto_cbc_encrypt_one(struct crypto_skcipher *tfm,
  					  const u8 *src, u8 *dst)
  {

  	crypto_cipher_encrypt_one(skcipher_cipher_simple(tfm), dst, src);

  }
  
  static int crypto_cbc_encrypt(struct skcipher_request *req)

  {

  	return crypto_cbc_encrypt_walk(req, crypto_cbc_encrypt_one);
  }

  static inline void crypto_cbc_decrypt_one(struct crypto_skcipher *tfm,
  					  const u8 *src, u8 *dst)
  {

  	crypto_cipher_decrypt_one(skcipher_cipher_simple(tfm), dst, src);

  }
  
  static int crypto_cbc_decrypt(struct skcipher_request *req)
  {
  	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  	struct skcipher_walk walk;

  	int err;

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

  	while (walk.nbytes) {
  		err = crypto_cbc_decrypt_blocks(&walk, tfm,
  						crypto_cbc_decrypt_one);
  		err = skcipher_walk_done(&walk, err);

  	}
  
  	return err;
  }

  static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
  {
  	struct skcipher_instance *inst;

  	struct crypto_alg *alg;

  	int err;

  	inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
  	if (IS_ERR(inst))
  		return PTR_ERR(inst);

  	err = -EINVAL;
  	if (!is_power_of_2(alg->cra_blocksize))

  		goto out_free_inst;

  	inst->alg.encrypt = crypto_cbc_encrypt;
  	inst->alg.decrypt = crypto_cbc_decrypt;

  	err = skcipher_register_instance(tmpl, inst);
  	if (err)

  		goto out_free_inst;
  	goto out_put_alg;

  out_free_inst:
  	inst->free(inst);
  out_put_alg:

  	crypto_mod_put(alg);

  	return err;

  }
  
  static struct crypto_template crypto_cbc_tmpl = {
  	.name = "cbc",

  	.create = crypto_cbc_create,

  	.module = THIS_MODULE,
  };
  
  static int __init crypto_cbc_module_init(void)
  {
  	return crypto_register_template(&crypto_cbc_tmpl);
  }
  
  static void __exit crypto_cbc_module_exit(void)
  {
  	crypto_unregister_template(&crypto_cbc_tmpl);
  }

  subsys_initcall(crypto_cbc_module_init);

  module_exit(crypto_cbc_module_exit);
  
  MODULE_LICENSE("GPL");

  MODULE_DESCRIPTION("CBC block cipher mode of operation");

  MODULE_ALIAS_CRYPTO("cbc");