/*
   * Hash: Hash algorithms under the crypto API
   * 
   * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License as published by the Free
   * Software Foundation; either version 2 of the License, or (at your option) 
   * any later version.
   *
   */
  
  #ifndef _CRYPTO_HASH_H
  #define _CRYPTO_HASH_H
  
  #include <linux/crypto.h>

  #include <linux/string.h>

  struct crypto_ahash;

  /**
   * DOC: Message Digest Algorithm Definitions
   *
   * These data structures define modular message digest algorithm
   * implementations, managed via crypto_register_ahash(),
   * crypto_register_shash(), crypto_unregister_ahash() and
   * crypto_unregister_shash().
   */
  
  /**
   * struct hash_alg_common - define properties of message digest
   * @digestsize: Size of the result of the transformation. A buffer of this size
   *	        must be available to the @final and @finup calls, so they can
   *	        store the resulting hash into it. For various predefined sizes,
   *	        search include/crypto/ using
   *	        git grep _DIGEST_SIZE include/crypto.
   * @statesize: Size of the block for partial state of the transformation. A
   *	       buffer of this size must be passed to the @export function as it
   *	       will save the partial state of the transformation into it. On the
   *	       other side, the @import function will load the state from a
   *	       buffer of this size as well.

   * @base: Start of data structure of cipher algorithm. The common data
   *	  structure of crypto_alg contains information common to all ciphers.
   *	  The hash_alg_common data structure now adds the hash-specific
   *	  information.

   */

  struct hash_alg_common {
  	unsigned int digestsize;
  	unsigned int statesize;
  
  	struct crypto_alg base;
  };
  
  struct ahash_request {
  	struct crypto_async_request base;
  
  	unsigned int nbytes;
  	struct scatterlist *src;
  	u8 *result;

  	/* This field may only be used by the ahash API code. */
  	void *priv;

  	void *__ctx[] CRYPTO_MINALIGN_ATTR;
  };

  #define AHASH_REQUEST_ON_STACK(name, ahash) \
  	char __##name##_desc[sizeof(struct ahash_request) + \
  		crypto_ahash_reqsize(ahash)] CRYPTO_MINALIGN_ATTR; \
  	struct ahash_request *name = (void *)__##name##_desc

  /**
   * struct ahash_alg - asynchronous message digest definition

   * @init: **[mandatory]** Initialize the transformation context. Intended only to initialize the

   *	  state of the HASH transformation at the beginning. This shall fill in

   *	  the internal structures used during the entire duration of the whole

   *	  transformation. No data processing happens at this point. Driver code
   *	  implementation must not use req->result.

   * @update: **[mandatory]** Push a chunk of data into the driver for transformation. This

   *	   function actually pushes blocks of data from upper layers into the
   *	   driver, which then passes those to the hardware as seen fit. This
   *	   function must not finalize the HASH transformation by calculating the
   *	   final message digest as this only adds more data into the
   *	   transformation. This function shall not modify the transformation
   *	   context, as this function may be called in parallel with the same
   *	   transformation object. Data processing can happen synchronously

   *	   [SHASH] or asynchronously [AHASH] at this point. Driver must not use
   *	   req->result.

   * @final: **[mandatory]** Retrieve result from the driver. This function finalizes the

   *	   transformation and retrieves the resulting hash from the driver and
   *	   pushes it back to upper layers. No data processing happens at this

   *	   point unless hardware requires it to finish the transformation
   *	   (then the data buffered by the device driver is processed).

   * @finup: **[optional]** Combination of @update and @final. This function is effectively a

   *	   combination of @update and @final calls issued in sequence. As some
   *	   hardware cannot do @update and @final separately, this callback was
   *	   added to allow such hardware to be used at least by IPsec. Data
   *	   processing can happen synchronously [SHASH] or asynchronously [AHASH]
   *	   at this point.
   * @digest: Combination of @init and @update and @final. This function
   *	    effectively behaves as the entire chain of operations, @init,
   *	    @update and @final issued in sequence. Just like @finup, this was
   *	    added for hardware which cannot do even the @finup, but can only do
   *	    the whole transformation in one run. Data processing can happen
   *	    synchronously [SHASH] or asynchronously [AHASH] at this point.
   * @setkey: Set optional key used by the hashing algorithm. Intended to push
   *	    optional key used by the hashing algorithm from upper layers into
   *	    the driver. This function can store the key in the transformation
   *	    context or can outright program it into the hardware. In the former
   *	    case, one must be careful to program the key into the hardware at
   *	    appropriate time and one must be careful that .setkey() can be
   *	    called multiple times during the existence of the transformation
   *	    object. Not  all hashing algorithms do implement this function as it
   *	    is only needed for keyed message digests. SHAx/MDx/CRCx do NOT
   *	    implement this function. HMAC(MDx)/HMAC(SHAx)/CMAC(AES) do implement
   *	    this function. This function must be called before any other of the
   *	    @init, @update, @final, @finup, @digest is called. No data
   *	    processing happens at this point.
   * @export: Export partial state of the transformation. This function dumps the
   *	    entire state of the ongoing transformation into a provided block of
   *	    data so it can be @import 'ed back later on. This is useful in case
   *	    you want to save partial result of the transformation after
   *	    processing certain amount of data and reload this partial result
   *	    multiple times later on for multiple re-use. No data processing

   *	    happens at this point. Driver must not use req->result.

   * @import: Import partial state of the transformation. This function loads the
   *	    entire state of the ongoing transformation from a provided block of
   *	    data so the transformation can continue from this point onward. No

   *	    data processing happens at this point. Driver must not use
   *	    req->result.

   * @halg: see struct hash_alg_common

   */

  struct ahash_alg {
  	int (*init)(struct ahash_request *req);
  	int (*update)(struct ahash_request *req);
  	int (*final)(struct ahash_request *req);
  	int (*finup)(struct ahash_request *req);
  	int (*digest)(struct ahash_request *req);
  	int (*export)(struct ahash_request *req, void *out);
  	int (*import)(struct ahash_request *req, const void *in);
  	int (*setkey)(struct crypto_ahash *tfm, const u8 *key,
  		      unsigned int keylen);
  
  	struct hash_alg_common halg;
  };

  struct shash_desc {
  	struct crypto_shash *tfm;
  	u32 flags;
  
  	void *__ctx[] CRYPTO_MINALIGN_ATTR;
  };

  #define SHASH_DESC_ON_STACK(shash, ctx)				  \
  	char __##shash##_desc[sizeof(struct shash_desc) +	  \
  		crypto_shash_descsize(ctx)] CRYPTO_MINALIGN_ATTR; \
  	struct shash_desc *shash = (struct shash_desc *)__##shash##_desc

  /**
   * struct shash_alg - synchronous message digest definition
   * @init: see struct ahash_alg
   * @update: see struct ahash_alg
   * @final: see struct ahash_alg
   * @finup: see struct ahash_alg
   * @digest: see struct ahash_alg
   * @export: see struct ahash_alg
   * @import: see struct ahash_alg
   * @setkey: see struct ahash_alg
   * @digestsize: see struct ahash_alg
   * @statesize: see struct ahash_alg

   * @descsize: Size of the operational state for the message digest. This state

   * 	      size is the memory size that needs to be allocated for
   *	      shash_desc.__ctx
   * @base: internally used
   */

  struct shash_alg {
  	int (*init)(struct shash_desc *desc);
  	int (*update)(struct shash_desc *desc, const u8 *data,
  		      unsigned int len);
  	int (*final)(struct shash_desc *desc, u8 *out);
  	int (*finup)(struct shash_desc *desc, const u8 *data,
  		     unsigned int len, u8 *out);
  	int (*digest)(struct shash_desc *desc, const u8 *data,
  		      unsigned int len, u8 *out);

  	int (*export)(struct shash_desc *desc, void *out);
  	int (*import)(struct shash_desc *desc, const void *in);

  	int (*setkey)(struct crypto_shash *tfm, const u8 *key,
  		      unsigned int keylen);
  
  	unsigned int descsize;

  
  	/* These fields must match hash_alg_common. */

  	unsigned int digestsize
  		__attribute__ ((aligned(__alignof__(struct hash_alg_common))));

  	unsigned int statesize;

  
  	struct crypto_alg base;
  };

  struct crypto_ahash {

  	int (*init)(struct ahash_request *req);
  	int (*update)(struct ahash_request *req);
  	int (*final)(struct ahash_request *req);
  	int (*finup)(struct ahash_request *req);
  	int (*digest)(struct ahash_request *req);
  	int (*export)(struct ahash_request *req, void *out);
  	int (*import)(struct ahash_request *req, const void *in);
  	int (*setkey)(struct crypto_ahash *tfm, const u8 *key,
  		      unsigned int keylen);

  	unsigned int reqsize;

  	struct crypto_tfm base;
  };

  struct crypto_shash {

  	unsigned int descsize;

  	struct crypto_tfm base;
  };

  /**
   * DOC: Asynchronous Message Digest API
   *
   * The asynchronous message digest API is used with the ciphers of type
   * CRYPTO_ALG_TYPE_AHASH (listed as type "ahash" in /proc/crypto)
   *
   * The asynchronous cipher operation discussion provided for the
   * CRYPTO_ALG_TYPE_ABLKCIPHER API applies here as well.
   */

  static inline struct crypto_ahash *__crypto_ahash_cast(struct crypto_tfm *tfm)
  {

  	return container_of(tfm, struct crypto_ahash, base);

  }

  /**
   * crypto_alloc_ahash() - allocate ahash cipher handle
   * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
   *	      ahash cipher
   * @type: specifies the type of the cipher
   * @mask: specifies the mask for the cipher
   *
   * Allocate a cipher handle for an ahash. The returned struct
   * crypto_ahash is the cipher handle that is required for any subsequent
   * API invocation for that ahash.
   *
   * 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_ahash *crypto_alloc_ahash(const char *alg_name, u32 type,
  					u32 mask);

  
  static inline struct crypto_tfm *crypto_ahash_tfm(struct crypto_ahash *tfm)
  {
  	return &tfm->base;
  }

  /**
   * crypto_free_ahash() - zeroize and free the ahash handle
   * @tfm: cipher handle to be freed
   */

  static inline void crypto_free_ahash(struct crypto_ahash *tfm)
  {

  	crypto_destroy_tfm(tfm, crypto_ahash_tfm(tfm));

  }

  /**
   * crypto_has_ahash() - Search for the availability of an ahash.
   * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
   *	      ahash
   * @type: specifies the type of the ahash
   * @mask: specifies the mask for the ahash
   *
   * Return: true when the ahash is known to the kernel crypto API; false
   *	   otherwise
   */
  int crypto_has_ahash(const char *alg_name, u32 type, u32 mask);

  static inline const char *crypto_ahash_alg_name(struct crypto_ahash *tfm)
  {
  	return crypto_tfm_alg_name(crypto_ahash_tfm(tfm));
  }
  
  static inline const char *crypto_ahash_driver_name(struct crypto_ahash *tfm)
  {
  	return crypto_tfm_alg_driver_name(crypto_ahash_tfm(tfm));
  }

  static inline unsigned int crypto_ahash_alignmask(
  	struct crypto_ahash *tfm)
  {
  	return crypto_tfm_alg_alignmask(crypto_ahash_tfm(tfm));
  }

  /**
   * crypto_ahash_blocksize() - obtain block size for cipher
   * @tfm: cipher handle
   *
   * The block size for the message digest cipher referenced with the cipher
   * handle is returned.
   *
   * Return: block size of cipher
   */
  static inline unsigned int crypto_ahash_blocksize(struct crypto_ahash *tfm)
  {
  	return crypto_tfm_alg_blocksize(crypto_ahash_tfm(tfm));
  }

  static inline struct hash_alg_common *__crypto_hash_alg_common(
  	struct crypto_alg *alg)
  {
  	return container_of(alg, struct hash_alg_common, base);
  }
  
  static inline struct hash_alg_common *crypto_hash_alg_common(
  	struct crypto_ahash *tfm)

  {

  	return __crypto_hash_alg_common(crypto_ahash_tfm(tfm)->__crt_alg);

  }

  /**
   * crypto_ahash_digestsize() - obtain message digest size
   * @tfm: cipher handle
   *
   * The size for the message digest created by the message digest cipher
   * referenced with the cipher handle is returned.
   *
   *
   * Return: message digest size of cipher
   */

  static inline unsigned int crypto_ahash_digestsize(struct crypto_ahash *tfm)
  {

  	return crypto_hash_alg_common(tfm)->digestsize;

  }

  /**
   * crypto_ahash_statesize() - obtain size of the ahash state
   * @tfm: cipher handle
   *
   * Return the size of the ahash state. With the crypto_ahash_export()
   * function, the caller can export the state into a buffer whose size is
   * defined with this function.
   *
   * Return: size of the ahash state
   */

  static inline unsigned int crypto_ahash_statesize(struct crypto_ahash *tfm)
  {
  	return crypto_hash_alg_common(tfm)->statesize;

  }
  
  static inline u32 crypto_ahash_get_flags(struct crypto_ahash *tfm)
  {
  	return crypto_tfm_get_flags(crypto_ahash_tfm(tfm));
  }
  
  static inline void crypto_ahash_set_flags(struct crypto_ahash *tfm, u32 flags)
  {
  	crypto_tfm_set_flags(crypto_ahash_tfm(tfm), flags);
  }
  
  static inline void crypto_ahash_clear_flags(struct crypto_ahash *tfm, u32 flags)
  {
  	crypto_tfm_clear_flags(crypto_ahash_tfm(tfm), flags);
  }

  /**
   * crypto_ahash_reqtfm() - obtain cipher handle from request
   * @req: asynchronous request handle that contains the reference to the ahash
   *	 cipher handle
   *
   * Return the ahash cipher handle that is registered with the asynchronous
   * request handle ahash_request.
   *
   * Return: ahash cipher handle
   */

  static inline struct crypto_ahash *crypto_ahash_reqtfm(
  	struct ahash_request *req)
  {
  	return __crypto_ahash_cast(req->base.tfm);
  }

  /**
   * crypto_ahash_reqsize() - obtain size of the request data structure
   * @tfm: cipher handle
   *

   * Return: size of the request data

   */

  static inline unsigned int crypto_ahash_reqsize(struct crypto_ahash *tfm)
  {

  	return tfm->reqsize;

  }

  static inline void *ahash_request_ctx(struct ahash_request *req)
  {
  	return req->__ctx;
  }

  /**
   * crypto_ahash_setkey - set key for cipher handle
   * @tfm: cipher handle
   * @key: buffer holding the key
   * @keylen: length of the key in bytes
   *
   * The caller provided key is set for the ahash cipher. The cipher
   * handle must point to a keyed hash in order for this function to succeed.
   *
   * Return: 0 if the setting of the key was successful; < 0 if an error occurred
   */

  int crypto_ahash_setkey(struct crypto_ahash *tfm, const u8 *key,
  			unsigned int keylen);

  
  /**
   * crypto_ahash_finup() - update and finalize message digest
   * @req: reference to the ahash_request handle that holds all information
   *	 needed to perform the cipher operation
   *
   * This function is a "short-hand" for the function calls of

   * crypto_ahash_update and crypto_ahash_final. The parameters have the same

   * meaning as discussed for those separate functions.
   *

   * Return: see crypto_ahash_final()

   */

  int crypto_ahash_finup(struct ahash_request *req);

  
  /**
   * crypto_ahash_final() - calculate message digest
   * @req: reference to the ahash_request handle that holds all information
   *	 needed to perform the cipher operation
   *
   * Finalize the message digest operation and create the message digest
   * based on all data added to the cipher handle. The message digest is placed
   * into the output buffer registered with the ahash_request handle.
   *

   * Return:
   * 0		if the message digest was successfully calculated;
   * -EINPROGRESS	if data is feeded into hardware (DMA) or queued for later;
   * -EBUSY	if queue is full and request should be resubmitted later;
   * other < 0	if an error occurred

   */

  int crypto_ahash_final(struct ahash_request *req);

  
  /**
   * crypto_ahash_digest() - calculate message digest for a buffer
   * @req: reference to the ahash_request handle that holds all information
   *	 needed to perform the cipher operation
   *
   * This function is a "short-hand" for the function calls of crypto_ahash_init,
   * crypto_ahash_update and crypto_ahash_final. The parameters have the same
   * meaning as discussed for those separate three functions.
   *

   * Return: see crypto_ahash_final()

   */

  int crypto_ahash_digest(struct ahash_request *req);

  /**
   * crypto_ahash_export() - extract current message digest state
   * @req: reference to the ahash_request handle whose state is exported
   * @out: output buffer of sufficient size that can hold the hash state
   *
   * This function exports the hash state of the ahash_request handle into the
   * caller-allocated output buffer out which must have sufficient size (e.g. by

   * calling crypto_ahash_statesize()).

   *
   * Return: 0 if the export was successful; < 0 if an error occurred
   */

  static inline int crypto_ahash_export(struct ahash_request *req, void *out)

  {

  	return crypto_ahash_reqtfm(req)->export(req, out);

  }

  /**
   * crypto_ahash_import() - import message digest state
   * @req: reference to ahash_request handle the state is imported into
   * @in: buffer holding the state
   *
   * This function imports the hash state into the ahash_request handle from the
   * input buffer. That buffer should have been generated with the
   * crypto_ahash_export function.
   *
   * Return: 0 if the import was successful; < 0 if an error occurred
   */

  static inline int crypto_ahash_import(struct ahash_request *req, const void *in)
  {

  	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
  
  	if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
  		return -ENOKEY;
  
  	return tfm->import(req, in);

  }

  /**
   * crypto_ahash_init() - (re)initialize message digest handle
   * @req: ahash_request handle that already is initialized with all necessary
   *	 data using the ahash_request_* API functions
   *
   * The call (re-)initializes the message digest referenced by the ahash_request
   * handle. Any potentially existing state created by previous operations is
   * discarded.
   *

   * Return: see crypto_ahash_final()

   */

  static inline int crypto_ahash_init(struct ahash_request *req)
  {

  	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
  
  	if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
  		return -ENOKEY;
  
  	return tfm->init(req);

  }

  /**
   * crypto_ahash_update() - add data to message digest for processing
   * @req: ahash_request handle that was previously initialized with the
   *	 crypto_ahash_init call.
   *
   * Updates the message digest state of the &ahash_request handle. The input data
   * is pointed to by the scatter/gather list registered in the &ahash_request
   * handle
   *

   * Return: see crypto_ahash_final()

   */

  static inline int crypto_ahash_update(struct ahash_request *req)
  {

  	return crypto_ahash_reqtfm(req)->update(req);

  }

  /**
   * DOC: Asynchronous Hash Request Handle
   *
   * The &ahash_request data structure contains all pointers to data
   * required for the asynchronous cipher operation. This includes the cipher
   * handle (which can be used by multiple &ahash_request instances), pointer
   * to plaintext and the message digest output buffer, asynchronous callback
   * function, etc. It acts as a handle to the ahash_request_* API calls in a
   * similar way as ahash handle to the crypto_ahash_* API calls.
   */
  
  /**
   * ahash_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 ahash handle in the request
   * data structure with a different one.
   */

  static inline void ahash_request_set_tfm(struct ahash_request *req,
  					 struct crypto_ahash *tfm)
  {
  	req->base.tfm = crypto_ahash_tfm(tfm);
  }

  /**
   * ahash_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 ahash
   * message digest API calls. During
   * the allocation, the provided ahash 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 ahash_request *ahash_request_alloc(
  	struct crypto_ahash *tfm, gfp_t gfp)
  {
  	struct ahash_request *req;
  
  	req = kmalloc(sizeof(struct ahash_request) +
  		      crypto_ahash_reqsize(tfm), gfp);
  
  	if (likely(req))
  		ahash_request_set_tfm(req, tfm);
  
  	return req;
  }

  /**
   * ahash_request_free() - zeroize and free the request data structure
   * @req: request data structure cipher handle to be freed
   */

  static inline void ahash_request_free(struct ahash_request *req)
  {

  	kzfree(req);

  }

  static inline void ahash_request_zero(struct ahash_request *req)
  {
  	memzero_explicit(req, sizeof(*req) +
  			      crypto_ahash_reqsize(crypto_ahash_reqtfm(req)));
  }

  static inline struct ahash_request *ahash_request_cast(
  	struct crypto_async_request *req)
  {
  	return container_of(req, struct ahash_request, base);
  }

  /**
   * ahash_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.
   *
   * This function allows setting the callback function that is triggered once
   * the cipher operation completes.
   *
   * The callback function is registered with the &ahash_request handle and

   * must comply with the following template::

   *
   *	void callback_function(struct crypto_async_request *req, int error)
   */

  static inline void ahash_request_set_callback(struct ahash_request *req,
  					      u32 flags,

  					      crypto_completion_t compl,

  					      void *data)
  {

  	req->base.complete = compl;

  	req->base.data = data;
  	req->base.flags = flags;
  }

  /**
   * ahash_request_set_crypt() - set data buffers
   * @req: ahash_request handle to be updated
   * @src: source scatter/gather list
   * @result: buffer that is filled with the message digest -- the caller must
   *	    ensure that the buffer has sufficient space by, for example, calling
   *	    crypto_ahash_digestsize()
   * @nbytes: number of bytes to process from the source scatter/gather list
   *
   * By using this call, the caller references the source scatter/gather list.
   * The source scatter/gather list points to the data the message digest is to
   * be calculated for.
   */

  static inline void ahash_request_set_crypt(struct ahash_request *req,
  					   struct scatterlist *src, u8 *result,
  					   unsigned int nbytes)
  {
  	req->src = src;
  	req->nbytes = nbytes;
  	req->result = result;
  }

  /**
   * DOC: Synchronous Message Digest API
   *
   * The synchronous message digest API is used with the ciphers of type
   * CRYPTO_ALG_TYPE_SHASH (listed as type "shash" in /proc/crypto)
   *
   * The message digest API is able to maintain state information for the
   * caller.
   *
   * The synchronous message digest API can store user-related context in in its
   * shash_desc request data structure.
   */
  
  /**
   * crypto_alloc_shash() - allocate message digest handle
   * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
   *	      message digest cipher
   * @type: specifies the type of the cipher
   * @mask: specifies the mask for the cipher
   *
   * Allocate a cipher handle for a message digest. The returned &struct
   * crypto_shash is the cipher handle that is required for any subsequent
   * API invocation for that message digest.
   *
   * 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_shash *crypto_alloc_shash(const char *alg_name, u32 type,
  					u32 mask);
  
  static inline struct crypto_tfm *crypto_shash_tfm(struct crypto_shash *tfm)
  {
  	return &tfm->base;
  }

  /**
   * crypto_free_shash() - zeroize and free the message digest handle
   * @tfm: cipher handle to be freed
   */

  static inline void crypto_free_shash(struct crypto_shash *tfm)
  {

  	crypto_destroy_tfm(tfm, crypto_shash_tfm(tfm));

  }

  static inline const char *crypto_shash_alg_name(struct crypto_shash *tfm)
  {
  	return crypto_tfm_alg_name(crypto_shash_tfm(tfm));
  }
  
  static inline const char *crypto_shash_driver_name(struct crypto_shash *tfm)
  {
  	return crypto_tfm_alg_driver_name(crypto_shash_tfm(tfm));
  }

  static inline unsigned int crypto_shash_alignmask(
  	struct crypto_shash *tfm)
  {
  	return crypto_tfm_alg_alignmask(crypto_shash_tfm(tfm));
  }

  /**
   * crypto_shash_blocksize() - obtain block size for cipher
   * @tfm: cipher handle
   *
   * The block size for the message digest cipher referenced with the cipher
   * handle is returned.
   *
   * Return: block size of cipher
   */

  static inline unsigned int crypto_shash_blocksize(struct crypto_shash *tfm)
  {
  	return crypto_tfm_alg_blocksize(crypto_shash_tfm(tfm));
  }

  static inline struct shash_alg *__crypto_shash_alg(struct crypto_alg *alg)
  {
  	return container_of(alg, struct shash_alg, base);
  }
  
  static inline struct shash_alg *crypto_shash_alg(struct crypto_shash *tfm)
  {
  	return __crypto_shash_alg(crypto_shash_tfm(tfm)->__crt_alg);
  }

  /**
   * crypto_shash_digestsize() - obtain message digest size
   * @tfm: cipher handle
   *
   * The size for the message digest created by the message digest cipher
   * referenced with the cipher handle is returned.
   *
   * Return: digest size of cipher
   */

  static inline unsigned int crypto_shash_digestsize(struct crypto_shash *tfm)
  {
  	return crypto_shash_alg(tfm)->digestsize;
  }

  static inline unsigned int crypto_shash_statesize(struct crypto_shash *tfm)
  {
  	return crypto_shash_alg(tfm)->statesize;
  }

  static inline u32 crypto_shash_get_flags(struct crypto_shash *tfm)
  {
  	return crypto_tfm_get_flags(crypto_shash_tfm(tfm));
  }
  
  static inline void crypto_shash_set_flags(struct crypto_shash *tfm, u32 flags)
  {
  	crypto_tfm_set_flags(crypto_shash_tfm(tfm), flags);
  }
  
  static inline void crypto_shash_clear_flags(struct crypto_shash *tfm, u32 flags)
  {
  	crypto_tfm_clear_flags(crypto_shash_tfm(tfm), flags);
  }

  /**
   * crypto_shash_descsize() - obtain the operational state size
   * @tfm: cipher handle
   *
   * The size of the operational state the cipher needs during operation is
   * returned for the hash referenced with the cipher handle. This size is
   * required to calculate the memory requirements to allow the caller allocating
   * sufficient memory for operational state.
   *
   * The operational state is defined with struct shash_desc where the size of
   * that data structure is to be calculated as
   * sizeof(struct shash_desc) + crypto_shash_descsize(alg)
   *
   * Return: size of the operational state
   */

  static inline unsigned int crypto_shash_descsize(struct crypto_shash *tfm)
  {

  	return tfm->descsize;

  }
  
  static inline void *shash_desc_ctx(struct shash_desc *desc)
  {
  	return desc->__ctx;
  }

  /**
   * crypto_shash_setkey() - set key for message digest
   * @tfm: cipher handle
   * @key: buffer holding the key
   * @keylen: length of the key in bytes
   *
   * The caller provided key is set for the keyed message digest cipher. The
   * cipher handle must point to a keyed message digest cipher in order for this
   * function to succeed.
   *
   * Return: 0 if the setting of the key was successful; < 0 if an error occurred
   */

  int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key,
  			unsigned int keylen);

  
  /**
   * crypto_shash_digest() - calculate message digest for buffer
   * @desc: see crypto_shash_final()
   * @data: see crypto_shash_update()
   * @len: see crypto_shash_update()
   * @out: see crypto_shash_final()
   *
   * This function is a "short-hand" for the function calls of crypto_shash_init,
   * crypto_shash_update and crypto_shash_final. The parameters have the same
   * meaning as discussed for those separate three functions.
   *
   * Return: 0 if the message digest creation was successful; < 0 if an error
   *	   occurred
   */

  int crypto_shash_digest(struct shash_desc *desc, const u8 *data,
  			unsigned int len, u8 *out);

  /**
   * crypto_shash_export() - extract operational state for message digest
   * @desc: reference to the operational state handle whose state is exported
   * @out: output buffer of sufficient size that can hold the hash state
   *
   * This function exports the hash state of the operational state handle into the
   * caller-allocated output buffer out which must have sufficient size (e.g. by
   * calling crypto_shash_descsize).
   *
   * Return: 0 if the export creation was successful; < 0 if an error occurred
   */

  static inline int crypto_shash_export(struct shash_desc *desc, void *out)

  {

  	return crypto_shash_alg(desc->tfm)->export(desc, out);

  }

  /**
   * crypto_shash_import() - import operational state
   * @desc: reference to the operational state handle the state imported into
   * @in: buffer holding the state
   *
   * This function imports the hash state into the operational state handle from
   * the input buffer. That buffer should have been generated with the
   * crypto_ahash_export function.
   *
   * Return: 0 if the import was successful; < 0 if an error occurred
   */

  static inline int crypto_shash_import(struct shash_desc *desc, const void *in)
  {

  	struct crypto_shash *tfm = desc->tfm;
  
  	if (crypto_shash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
  		return -ENOKEY;
  
  	return crypto_shash_alg(tfm)->import(desc, in);

  }

  /**
   * crypto_shash_init() - (re)initialize message digest
   * @desc: operational state handle that is already filled
   *
   * The call (re-)initializes the message digest referenced by the
   * operational state handle. Any potentially existing state created by
   * previous operations is discarded.
   *
   * Return: 0 if the message digest initialization was successful; < 0 if an
   *	   error occurred
   */

  static inline int crypto_shash_init(struct shash_desc *desc)
  {

  	struct crypto_shash *tfm = desc->tfm;
  
  	if (crypto_shash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
  		return -ENOKEY;
  
  	return crypto_shash_alg(tfm)->init(desc);

  }

  /**
   * crypto_shash_update() - add data to message digest for processing
   * @desc: operational state handle that is already initialized
   * @data: input data to be added to the message digest
   * @len: length of the input data
   *
   * Updates the message digest state of the operational state handle.
   *
   * Return: 0 if the message digest update was successful; < 0 if an error
   *	   occurred
   */

  int crypto_shash_update(struct shash_desc *desc, const u8 *data,
  			unsigned int len);

  
  /**
   * crypto_shash_final() - calculate message digest
   * @desc: operational state handle that is already filled with data
   * @out: output buffer filled with the message digest
   *
   * Finalize the message digest operation and create the message digest
   * based on all data added to the cipher handle. The message digest is placed
   * into the output buffer. The caller must ensure that the output buffer is
   * large enough by using crypto_shash_digestsize.
   *
   * Return: 0 if the message digest creation was successful; < 0 if an error
   *	   occurred
   */

  int crypto_shash_final(struct shash_desc *desc, u8 *out);

  
  /**
   * crypto_shash_finup() - calculate message digest of buffer
   * @desc: see crypto_shash_final()
   * @data: see crypto_shash_update()
   * @len: see crypto_shash_update()
   * @out: see crypto_shash_final()
   *
   * This function is a "short-hand" for the function calls of
   * crypto_shash_update and crypto_shash_final. The parameters have the same
   * meaning as discussed for those separate functions.
   *
   * Return: 0 if the message digest creation was successful; < 0 if an error
   *	   occurred
   */

  int crypto_shash_finup(struct shash_desc *desc, const u8 *data,
  		       unsigned int len, u8 *out);

  static inline void shash_desc_zero(struct shash_desc *desc)
  {
  	memzero_explicit(desc,
  			 sizeof(*desc) + crypto_shash_descsize(desc->tfm));
  }

  #endif	/* _CRYPTO_HASH_H */