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

  /*
   * AEAD: Authenticated Encryption with Associated Data
   * 

   * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>

   */
  
  #ifndef _CRYPTO_AEAD_H
  #define _CRYPTO_AEAD_H
  
  #include <linux/crypto.h>
  #include <linux/kernel.h>

  #include <linux/slab.h>

  
  /**

   * DOC: Authenticated Encryption With Associated Data (AEAD) Cipher API
   *
   * The AEAD cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_AEAD
   * (listed as type "aead" in /proc/crypto)
   *
   * The most prominent examples for this type of encryption is GCM and CCM.
   * However, the kernel supports other types of AEAD ciphers which are defined
   * with the following cipher string:
   *
   *	authenc(keyed message digest, block cipher)
   *
   * For example: authenc(hmac(sha256), cbc(aes))
   *

   * The example code provided for the symmetric key cipher operation
   * applies here as well. Naturally all *skcipher* symbols must be exchanged

   * the *aead* pendants discussed in the following. In addition, for the AEAD

   * operation, the aead_request_set_ad function must be used to set the

   * pointer to the associated data memory location before performing the
   * encryption or decryption operation. In case of an encryption, the associated
   * data memory is filled during the encryption operation. For decryption, the
   * associated data memory must contain data that is used to verify the integrity
   * of the decrypted data. Another deviation from the asynchronous block cipher
   * operation is that the caller should explicitly check for -EBADMSG of the
   * crypto_aead_decrypt. That error indicates an authentication error, i.e.
   * a breach in the integrity of the message. In essence, that -EBADMSG error
   * code is the key bonus an AEAD cipher has over "standard" block chaining
   * modes.

   *
   * Memory Structure:
   *

   * The source scatterlist must contain the concatenation of
   * associated data || plaintext or ciphertext.

   *

   * The destination scatterlist has the same layout, except that the plaintext
   * (resp. ciphertext) will grow (resp. shrink) by the authentication tag size
   * during encryption (resp. decryption).

   *

   * In-place encryption/decryption is enabled by using the same scatterlist
   * pointer for both the source and destination.

   *

   * Even in the out-of-place case, space must be reserved in the destination for
   * the associated data, even though it won't be written to.  This makes the
   * in-place and out-of-place cases more consistent.  It is permissible for the
   * "destination" associated data to alias the "source" associated data.

   *

   * As with the other scatterlist crypto APIs, zero-length scatterlist elements
   * are not allowed in the used part of the scatterlist.  Thus, if there is no
   * associated data, the first element must point to the plaintext/ciphertext.
   *
   * To meet the needs of IPsec, a special quirk applies to rfc4106, rfc4309,
   * rfc4543, and rfc7539esp ciphers.  For these ciphers, the final 'ivsize' bytes
   * of the associated data buffer must contain a second copy of the IV.  This is
   * in addition to the copy passed to aead_request_set_crypt().  These two IV
   * copies must not differ; different implementations of the same algorithm may
   * behave differently in that case.  Note that the algorithm might not actually
   * treat the IV as associated data; nevertheless the length passed to
   * aead_request_set_ad() must include it.

   */

  struct crypto_aead;

  /**
   *	struct aead_request - AEAD request
   *	@base: Common attributes for async crypto requests
   *	@assoclen: Length in bytes of associated data for authentication
   *	@cryptlen: Length of data to be encrypted or decrypted
   *	@iv: Initialisation vector

   *	@src: Source data
   *	@dst: Destination data
   *	@__ctx: Start of private context data
   */
  struct aead_request {
  	struct crypto_async_request base;
  
  	unsigned int assoclen;
  	unsigned int cryptlen;
  
  	u8 *iv;

  	struct scatterlist *src;
  	struct scatterlist *dst;
  
  	void *__ctx[] CRYPTO_MINALIGN_ATTR;
  };
  
  /**

   * struct aead_alg - AEAD cipher definition
   * @maxauthsize: Set the maximum authentication tag size supported by the
   *		 transformation. A transformation may support smaller tag sizes.
   *		 As the authentication tag is a message digest to ensure the
   *		 integrity of the encrypted data, a consumer typically wants the
   *		 largest authentication tag possible as defined by this
   *		 variable.
   * @setauthsize: Set authentication size for the AEAD transformation. This
   *		 function is used to specify the consumer requested size of the
   * 		 authentication tag to be either generated by the transformation
   *		 during encryption or the size of the authentication tag to be
   *		 supplied during the decryption operation. This function is also
   *		 responsible for checking the authentication tag size for
   *		 validity.

   * @setkey: see struct skcipher_alg
   * @encrypt: see struct skcipher_alg
   * @decrypt: see struct skcipher_alg

   * @ivsize: see struct skcipher_alg
   * @chunksize: see struct skcipher_alg

   * @init: Initialize the cryptographic transformation object. This function
   *	  is used to initialize the cryptographic transformation object.
   *	  This function is called only once at the instantiation time, right
   *	  after the transformation context was allocated. In case the
   *	  cryptographic hardware has some special requirements which need to
   *	  be handled by software, this function shall check for the precise
   *	  requirement of the transformation and put any software fallbacks
   *	  in place.
   * @exit: Deinitialize the cryptographic transformation object. This is a
   *	  counterpart to @init, used to remove various changes set in
   *	  @init.

   * @base: Definition of a generic crypto cipher algorithm.

   *
   * All fields except @ivsize is mandatory and must be filled.
   */
  struct aead_alg {
  	int (*setkey)(struct crypto_aead *tfm, const u8 *key,
  	              unsigned int keylen);
  	int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize);
  	int (*encrypt)(struct aead_request *req);
  	int (*decrypt)(struct aead_request *req);

  	int (*init)(struct crypto_aead *tfm);
  	void (*exit)(struct crypto_aead *tfm);

  	unsigned int ivsize;
  	unsigned int maxauthsize;

  	unsigned int chunksize;

  
  	struct crypto_alg base;
  };

  struct crypto_aead {

  	unsigned int authsize;
  	unsigned int reqsize;
  
  	struct crypto_tfm base;
  };
  
  static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
  {
  	return container_of(tfm, struct crypto_aead, base);
  }
  
  /**
   * crypto_alloc_aead() - allocate AEAD cipher handle
   * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
   *	     AEAD cipher
   * @type: specifies the type of the cipher
   * @mask: specifies the mask for the cipher
   *
   * Allocate a cipher handle for an AEAD. The returned struct
   * crypto_aead is the cipher handle that is required for any subsequent
   * API invocation for that AEAD.
   *
   * Return: allocated cipher handle in case of success; IS_ERR() is true in case
   *	   of an error, PTR_ERR() returns the error code.
   */
  struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
  
  static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
  {
  	return &tfm->base;
  }
  
  /**
   * crypto_free_aead() - zeroize and free aead handle
   * @tfm: cipher handle to be freed
   */
  static inline void crypto_free_aead(struct crypto_aead *tfm)
  {
  	crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
  }

  static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
  {
  	return container_of(crypto_aead_tfm(tfm)->__crt_alg,
  			    struct aead_alg, base);
  }
  
  static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
  {

  	return alg->ivsize;

  }

  /**
   * crypto_aead_ivsize() - obtain IV size
   * @tfm: cipher handle
   *
   * The size of the IV for the aead referenced by the cipher handle is
   * returned. This IV size may be zero if the cipher does not need an IV.
   *
   * Return: IV size in bytes
   */
  static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
  {

  	return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));

  }
  
  /**
   * crypto_aead_authsize() - obtain maximum authentication data size
   * @tfm: cipher handle
   *
   * The maximum size of the authentication data for the AEAD cipher referenced
   * by the AEAD cipher handle is returned. The authentication data size may be
   * zero if the cipher implements a hard-coded maximum.
   *
   * The authentication data may also be known as "tag value".
   *
   * Return: authentication data size / tag size in bytes
   */
  static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
  {
  	return tfm->authsize;
  }

  static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg)
  {
  	return alg->maxauthsize;
  }
  
  static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead)
  {
  	return crypto_aead_alg_maxauthsize(crypto_aead_alg(aead));
  }

  /**
   * crypto_aead_blocksize() - obtain block size of cipher
   * @tfm: cipher handle
   *
   * The block size for the AEAD referenced with the cipher handle is returned.
   * The caller may use that information to allocate appropriate memory for the
   * data returned by the encryption or decryption operation
   *
   * Return: block size of cipher
   */
  static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
  {
  	return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
  }
  
  static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
  {
  	return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
  }
  
  static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
  {
  	return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
  }
  
  static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
  {
  	crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
  }
  
  static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
  {
  	crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
  }
  
  /**
   * crypto_aead_setkey() - set key for cipher
   * @tfm: cipher handle
   * @key: buffer holding the key
   * @keylen: length of the key in bytes
   *
   * The caller provided key is set for the AEAD referenced by the cipher
   * handle.
   *
   * Note, the key length determines the cipher type. Many block ciphers implement
   * different cipher modes depending on the key size, such as AES-128 vs AES-192
   * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
   * is performed.
   *
   * Return: 0 if the setting of the key was successful; < 0 if an error occurred
   */
  int crypto_aead_setkey(struct crypto_aead *tfm,
  		       const u8 *key, unsigned int keylen);
  
  /**
   * crypto_aead_setauthsize() - set authentication data size
   * @tfm: cipher handle
   * @authsize: size of the authentication data / tag in bytes
   *
   * Set the authentication data size / tag size. AEAD requires an authentication
   * tag (or MAC) in addition to the associated data.
   *
   * Return: 0 if the setting of the key was successful; < 0 if an error occurred
   */
  int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
  
  static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
  {
  	return __crypto_aead_cast(req->base.tfm);
  }
  
  /**
   * crypto_aead_encrypt() - encrypt plaintext
   * @req: reference to the aead_request handle that holds all information
   *	 needed to perform the cipher operation
   *
   * Encrypt plaintext data using the aead_request handle. That data structure
   * and how it is filled with data is discussed with the aead_request_*
   * functions.
   *
   * IMPORTANT NOTE The encryption operation creates the authentication data /
   *		  tag. That data is concatenated with the created ciphertext.
   *		  The ciphertext memory size is therefore the given number of
   *		  block cipher blocks + the size defined by the
   *		  crypto_aead_setauthsize invocation. The caller must ensure
   *		  that sufficient memory is available for the ciphertext and
   *		  the authentication tag.
   *
   * Return: 0 if the cipher operation was successful; < 0 if an error occurred
   */

  int crypto_aead_encrypt(struct aead_request *req);

  
  /**
   * crypto_aead_decrypt() - decrypt ciphertext

   * @req: reference to the aead_request handle that holds all information

   *	 needed to perform the cipher operation
   *
   * Decrypt ciphertext data using the aead_request handle. That data structure
   * and how it is filled with data is discussed with the aead_request_*
   * functions.
   *
   * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
   *		  authentication data / tag. That authentication data / tag
   *		  must have the size defined by the crypto_aead_setauthsize
   *		  invocation.
   *
   *
   * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
   *	   cipher operation performs the authentication of the data during the
   *	   decryption operation. Therefore, the function returns this error if
   *	   the authentication of the ciphertext was unsuccessful (i.e. the
   *	   integrity of the ciphertext or the associated data was violated);
   *	   < 0 if an error occurred.
   */

  int crypto_aead_decrypt(struct aead_request *req);

  
  /**
   * DOC: Asynchronous AEAD Request Handle
   *
   * The aead_request data structure contains all pointers to data required for
   * the AEAD cipher operation. This includes the cipher handle (which can be
   * used by multiple aead_request instances), pointer to plaintext and
   * ciphertext, asynchronous callback function, etc. It acts as a handle to the
   * aead_request_* API calls in a similar way as AEAD handle to the
   * crypto_aead_* API calls.
   */
  
  /**
   * crypto_aead_reqsize() - obtain size of the request data structure
   * @tfm: cipher handle
   *
   * Return: number of bytes
   */

  static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
  {
  	return tfm->reqsize;
  }

  
  /**
   * aead_request_set_tfm() - update cipher handle reference in request
   * @req: request handle to be modified
   * @tfm: cipher handle that shall be added to the request handle
   *
   * Allow the caller to replace the existing aead handle in the request
   * data structure with a different one.
   */
  static inline void aead_request_set_tfm(struct aead_request *req,
  					struct crypto_aead *tfm)
  {

  	req->base.tfm = crypto_aead_tfm(tfm);

  }
  
  /**
   * aead_request_alloc() - allocate request data structure
   * @tfm: cipher handle to be registered with the request
   * @gfp: memory allocation flag that is handed to kmalloc by the API call.
   *
   * Allocate the request data structure that must be used with the AEAD
   * encrypt and decrypt API calls. During the allocation, the provided aead
   * handle is registered in the request data structure.
   *

   * Return: allocated request handle in case of success, or NULL if out of memory

   */
  static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
  						      gfp_t gfp)
  {
  	struct aead_request *req;
  
  	req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
  
  	if (likely(req))
  		aead_request_set_tfm(req, tfm);
  
  	return req;
  }
  
  /**
   * aead_request_free() - zeroize and free request data structure
   * @req: request data structure cipher handle to be freed
   */
  static inline void aead_request_free(struct aead_request *req)
  {

  	kfree_sensitive(req);

  }
  
  /**
   * aead_request_set_callback() - set asynchronous callback function
   * @req: request handle
   * @flags: specify zero or an ORing of the flags
   *	   CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
   *	   increase the wait queue beyond the initial maximum size;
   *	   CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
   * @compl: callback function pointer to be registered with the request handle
   * @data: The data pointer refers to memory that is not used by the kernel
   *	  crypto API, but provided to the callback function for it to use. Here,
   *	  the caller can provide a reference to memory the callback function can
   *	  operate on. As the callback function is invoked asynchronously to the
   *	  related functionality, it may need to access data structures of the
   *	  related functionality which can be referenced using this pointer. The
   *	  callback function can access the memory via the "data" field in the
   *	  crypto_async_request data structure provided to the callback function.
   *
   * Setting the callback function that is triggered once the cipher operation
   * completes
   *
   * The callback function is registered with the aead_request handle and

   * must comply with the following template::

   *
   *	void callback_function(struct crypto_async_request *req, int error)
   */
  static inline void aead_request_set_callback(struct aead_request *req,
  					     u32 flags,
  					     crypto_completion_t compl,
  					     void *data)
  {
  	req->base.complete = compl;
  	req->base.data = data;
  	req->base.flags = flags;
  }
  
  /**
   * aead_request_set_crypt - set data buffers
   * @req: request handle
   * @src: source scatter / gather list
   * @dst: destination scatter / gather list
   * @cryptlen: number of bytes to process from @src
   * @iv: IV for the cipher operation which must comply with the IV size defined
   *      by crypto_aead_ivsize()
   *

   * Setting the source data and destination data scatter / gather lists which
   * hold the associated data concatenated with the plaintext or ciphertext. See
   * below for the authentication tag.

   *
   * For encryption, the source is treated as the plaintext and the
   * destination is the ciphertext. For a decryption operation, the use is
   * reversed - the source is the ciphertext and the destination is the plaintext.
   *

   * The memory structure for cipher operation has the following structure:
   *
   * - AEAD encryption input:  assoc data || plaintext
   * - AEAD encryption output: assoc data || cipherntext || auth tag
   * - AEAD decryption input:  assoc data || ciphertext || auth tag
   * - AEAD decryption output: assoc data || plaintext
   *
   * Albeit the kernel requires the presence of the AAD buffer, however,
   * the kernel does not fill the AAD buffer in the output case. If the
   * caller wants to have that data buffer filled, the caller must either
   * use an in-place cipher operation (i.e. same memory location for
   * input/output memory location).

   */
  static inline void aead_request_set_crypt(struct aead_request *req,
  					  struct scatterlist *src,
  					  struct scatterlist *dst,
  					  unsigned int cryptlen, u8 *iv)
  {
  	req->src = src;
  	req->dst = dst;
  	req->cryptlen = cryptlen;
  	req->iv = iv;
  }
  
  /**

   * aead_request_set_ad - set associated data information
   * @req: request handle
   * @assoclen: number of bytes in associated data

   *
   * Setting the AD information.  This function sets the length of

   * the associated data.

   */
  static inline void aead_request_set_ad(struct aead_request *req,

  				       unsigned int assoclen)

  {
  	req->assoclen = assoclen;

  }

  #endif	/* _CRYPTO_AEAD_H */