/*
   * Key-agreement Protocol Primitives (KPP)
   *
   * Copyright (c) 2016, Intel Corporation
   * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
   *
   * 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_KPP_
  #define _CRYPTO_KPP_
  #include <linux/crypto.h>
  
  /**
   * struct kpp_request
   *
   * @base:	Common attributes for async crypto requests
   * @src:	Source data
   * @dst:	Destination data
   * @src_len:	Size of the input buffer
   * @dst_len:	Size of the output buffer. It needs to be at least
   *		as big as the expected result depending	on the operation
   *		After operation it will be updated with the actual size of the
   *		result. In case of error where the dst sgl size was insufficient,
   *		it will be updated to the size required for the operation.
   * @__ctx:	Start of private context data
   */
  struct kpp_request {
  	struct crypto_async_request base;
  	struct scatterlist *src;
  	struct scatterlist *dst;
  	unsigned int src_len;
  	unsigned int dst_len;
  	void *__ctx[] CRYPTO_MINALIGN_ATTR;
  };
  
  /**
   * struct crypto_kpp - user-instantiated object which encapsulate
   * algorithms and core processing logic
   *
   * @base:	Common crypto API algorithm data structure
   */
  struct crypto_kpp {
  	struct crypto_tfm base;
  };
  
  /**
   * struct kpp_alg - generic key-agreement protocol primitives
   *
   * @set_secret:		Function invokes the protocol specific function to
   *			store the secret private key along with parameters.

   *			The implementation knows how to decode the buffer

   * @generate_public_key: Function generate the public key to be sent to the
   *			counterpart. In case of error, where output is not big
   *			enough req->dst_len will be updated to the size
   *			required
   * @compute_shared_secret: Function compute the shared secret as defined by
   *			the algorithm. The result is given back to the user.
   *			In case of error, where output is not big enough,
   *			req->dst_len will be updated to the size required
   * @max_size:		Function returns the size of the output buffer
   * @init:		Initialize the object. This is called only once at
   *			instantiation time. In case the cryptographic hardware
   *			needs to be initialized. Software fallback should be
   *			put in place here.
   * @exit:		Undo everything @init did.
   *
   * @reqsize:		Request context size required by algorithm
   *			implementation

   * @base:		Common crypto API algorithm data structure

   */
  struct kpp_alg {

  	int (*set_secret)(struct crypto_kpp *tfm, const void *buffer,

  			  unsigned int len);
  	int (*generate_public_key)(struct kpp_request *req);
  	int (*compute_shared_secret)(struct kpp_request *req);

  	unsigned int (*max_size)(struct crypto_kpp *tfm);

  
  	int (*init)(struct crypto_kpp *tfm);
  	void (*exit)(struct crypto_kpp *tfm);
  
  	unsigned int reqsize;
  	struct crypto_alg base;
  };
  
  /**

   * DOC: Generic Key-agreement Protocol Primitives API

   *
   * The KPP API is used with the algorithm type
   * CRYPTO_ALG_TYPE_KPP (listed as type "kpp" in /proc/crypto)
   */
  
  /**
   * crypto_alloc_kpp() - allocate KPP tfm handle
   * @alg_name: is the name of the kpp algorithm (e.g. "dh", "ecdh")
   * @type: specifies the type of the algorithm
   * @mask: specifies the mask for the algorithm
   *
   * Allocate a handle for kpp algorithm. The returned struct crypto_kpp

   * is required for any following API invocation

   *
   * Return: allocated handle in case of success; IS_ERR() is true in case of
   *	   an error, PTR_ERR() returns the error code.
   */
  struct crypto_kpp *crypto_alloc_kpp(const char *alg_name, u32 type, u32 mask);
  
  static inline struct crypto_tfm *crypto_kpp_tfm(struct crypto_kpp *tfm)
  {
  	return &tfm->base;
  }
  
  static inline struct kpp_alg *__crypto_kpp_alg(struct crypto_alg *alg)
  {
  	return container_of(alg, struct kpp_alg, base);
  }
  
  static inline struct crypto_kpp *__crypto_kpp_tfm(struct crypto_tfm *tfm)
  {
  	return container_of(tfm, struct crypto_kpp, base);
  }
  
  static inline struct kpp_alg *crypto_kpp_alg(struct crypto_kpp *tfm)
  {
  	return __crypto_kpp_alg(crypto_kpp_tfm(tfm)->__crt_alg);
  }
  
  static inline unsigned int crypto_kpp_reqsize(struct crypto_kpp *tfm)
  {
  	return crypto_kpp_alg(tfm)->reqsize;
  }
  
  static inline void kpp_request_set_tfm(struct kpp_request *req,
  				       struct crypto_kpp *tfm)
  {
  	req->base.tfm = crypto_kpp_tfm(tfm);
  }
  
  static inline struct crypto_kpp *crypto_kpp_reqtfm(struct kpp_request *req)
  {
  	return __crypto_kpp_tfm(req->base.tfm);
  }

  static inline u32 crypto_kpp_get_flags(struct crypto_kpp *tfm)
  {
  	return crypto_tfm_get_flags(crypto_kpp_tfm(tfm));
  }
  
  static inline void crypto_kpp_set_flags(struct crypto_kpp *tfm, u32 flags)
  {
  	crypto_tfm_set_flags(crypto_kpp_tfm(tfm), flags);
  }

  /**
   * crypto_free_kpp() - free KPP tfm handle
   *
   * @tfm: KPP tfm handle allocated with crypto_alloc_kpp()
   */
  static inline void crypto_free_kpp(struct crypto_kpp *tfm)
  {
  	crypto_destroy_tfm(tfm, crypto_kpp_tfm(tfm));
  }
  
  /**
   * kpp_request_alloc() - allocates kpp request
   *
   * @tfm:	KPP tfm handle allocated with crypto_alloc_kpp()
   * @gfp:	allocation flags
   *
   * Return: allocated handle in case of success or NULL in case of an error.
   */
  static inline struct kpp_request *kpp_request_alloc(struct crypto_kpp *tfm,
  						    gfp_t gfp)
  {
  	struct kpp_request *req;
  
  	req = kmalloc(sizeof(*req) + crypto_kpp_reqsize(tfm), gfp);
  	if (likely(req))
  		kpp_request_set_tfm(req, tfm);
  
  	return req;
  }
  
  /**
   * kpp_request_free() - zeroize and free kpp request
   *
   * @req:	request to free
   */
  static inline void kpp_request_free(struct kpp_request *req)
  {
  	kzfree(req);
  }
  
  /**
   * kpp_request_set_callback() - Sets an asynchronous callback.
   *
   * Callback will be called when an asynchronous operation on a given
   * request is finished.
   *
   * @req:	request that the callback will be set for
   * @flgs:	specify for instance if the operation may backlog
   * @cmpl:	callback which will be called
   * @data:	private data used by the caller
   */
  static inline void kpp_request_set_callback(struct kpp_request *req,
  					    u32 flgs,
  					    crypto_completion_t cmpl,
  					    void *data)
  {
  	req->base.complete = cmpl;
  	req->base.data = data;
  	req->base.flags = flgs;
  }
  
  /**
   * kpp_request_set_input() - Sets input buffer
   *
   * Sets parameters required by generate_public_key
   *
   * @req:	kpp request
   * @input:	ptr to input scatter list
   * @input_len:	size of the input scatter list
   */
  static inline void kpp_request_set_input(struct kpp_request *req,
  					 struct scatterlist *input,
  					 unsigned int input_len)
  {
  	req->src = input;
  	req->src_len = input_len;
  }
  
  /**
   * kpp_request_set_output() - Sets output buffer
   *
   * Sets parameters required by kpp operation
   *
   * @req:	kpp request
   * @output:	ptr to output scatter list
   * @output_len:	size of the output scatter list
   */
  static inline void kpp_request_set_output(struct kpp_request *req,
  					  struct scatterlist *output,
  					  unsigned int output_len)
  {
  	req->dst = output;
  	req->dst_len = output_len;
  }
  
  enum {
  	CRYPTO_KPP_SECRET_TYPE_UNKNOWN,

  	CRYPTO_KPP_SECRET_TYPE_DH,

  	CRYPTO_KPP_SECRET_TYPE_ECDH,

  };
  
  /**
   * struct kpp_secret - small header for packing secret buffer
   *
   * @type:	define type of secret. Each kpp type will define its own
   * @len:	specify the len of the secret, include the header, that
   *		follows the struct
   */
  struct kpp_secret {
  	unsigned short type;
  	unsigned short len;
  };
  
  /**
   * crypto_kpp_set_secret() - Invoke kpp operation
   *
   * Function invokes the specific kpp operation for a given alg.
   *
   * @tfm:	tfm handle

   * @buffer:	Buffer holding the packet representation of the private
   *		key. The structure of the packet key depends on the particular
   *		KPP implementation. Packing and unpacking helpers are provided
   *		for ECDH and DH (see the respective header files for those
   *		implementations).
   * @len:	Length of the packet private key buffer.

   *
   * Return: zero on success; error code in case of error
   */

  static inline int crypto_kpp_set_secret(struct crypto_kpp *tfm,
  					const void *buffer, unsigned int len)

  {
  	struct kpp_alg *alg = crypto_kpp_alg(tfm);
  
  	return alg->set_secret(tfm, buffer, len);
  }
  
  /**
   * crypto_kpp_generate_public_key() - Invoke kpp operation
   *
   * Function invokes the specific kpp operation for generating the public part

   * for a given kpp algorithm.
   *
   * To generate a private key, the caller should use a random number generator.
   * The output of the requested length serves as the private key.

   *
   * @req:	kpp key request
   *
   * Return: zero on success; error code in case of error
   */
  static inline int crypto_kpp_generate_public_key(struct kpp_request *req)
  {
  	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
  	struct kpp_alg *alg = crypto_kpp_alg(tfm);
  
  	return alg->generate_public_key(req);
  }
  
  /**
   * crypto_kpp_compute_shared_secret() - Invoke kpp operation
   *
   * Function invokes the specific kpp operation for computing the shared secret
   * for a given kpp algorithm.
   *
   * @req:	kpp key request
   *
   * Return: zero on success; error code in case of error
   */
  static inline int crypto_kpp_compute_shared_secret(struct kpp_request *req)
  {
  	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
  	struct kpp_alg *alg = crypto_kpp_alg(tfm);
  
  	return alg->compute_shared_secret(req);
  }
  
  /**
   * crypto_kpp_maxsize() - Get len for output buffer
   *

   * Function returns the output buffer size required for a given key.
   * Function assumes that the key is already set in the transformation. If this
   * function is called without a setkey or with a failed setkey, you will end up
   * in a NULL dereference.

   *
   * @tfm:	KPP tfm handle allocated with crypto_alloc_kpp()

   */

  static inline unsigned int crypto_kpp_maxsize(struct crypto_kpp *tfm)

  {
  	struct kpp_alg *alg = crypto_kpp_alg(tfm);
  
  	return alg->max_size(tfm);
  }
  
  #endif