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crypto: doc - ABLKCIPHER API documentation 

The API function calls exported by the kernel crypto API for
asynchronous block ciphers to be used by consumers are documented.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stephan Mueller 2014-11-12 05:28:22 +01:00 committed by Herbert Xu
parent 0d7f488f03
commit f13ec330a7
1 changed files with 206 additions and 0 deletions
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206
include/linux/crypto.h
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@ -821,6 +821,50 @@ static inline u32 crypto_skcipher_mask(u32 mask)
return mask;
}
/**
* DOC: Asynchronous Block Cipher API
*
* Asynchronous block cipher API is used with the ciphers of type
* CRYPTO_ALG_TYPE_ABLKCIPHER (listed as type "ablkcipher" in /proc/crypto).
*
* Asynchronous cipher operations imply that the function invocation for a
* cipher request returns immediately before the completion of the operation.
* The cipher request is scheduled as a separate kernel thread and therefore
* load-balanced on the different CPUs via the process scheduler. To allow
* the kernel crypto API to inform the caller about the completion of a cipher
* request, the caller must provide a callback function. That function is
* invoked with the cipher handle when the request completes.
*
* To support the asynchronous operation, additional information than just the
* cipher handle must be supplied to the kernel crypto API. That additional
* information is given by filling in the ablkcipher_request data structure.
*
* For the asynchronous block cipher API, the state is maintained with the tfm
* cipher handle. A single tfm can be used across multiple calls and in
* parallel. For asynchronous block cipher calls, context data supplied and
* only used by the caller can be referenced the request data structure in
* addition to the IV used for the cipher request. The maintenance of such
* state information would be important for a crypto driver implementer to
* have, because when calling the callback function upon completion of the
* cipher operation, that callback function may need some information about
* which operation just finished if it invoked multiple in parallel. This
* state information is unused by the kernel crypto API.
*/
/**
* crypto_alloc_ablkcipher() - allocate asynchronous block cipher handle
* @alg_name: is the cra_name / name or cra_driver_name / driver name of the
* ablkcipher cipher
* @type: specifies the type of the cipher
* @mask: specifies the mask for the cipher
*
* Allocate a cipher handle for an ablkcipher. The returned struct
* crypto_ablkcipher is the cipher handle that is required for any subsequent
* API invocation for that ablkcipher.
*
* 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_ablkcipher *crypto_alloc_ablkcipher(const char *alg_name,
u32 type, u32 mask);
@ -830,11 +874,25 @@ static inline struct crypto_tfm *crypto_ablkcipher_tfm(
return &tfm->base;
}
/**
* crypto_free_ablkcipher() - zeroize and free cipher handle
* @tfm: cipher handle to be freed
*/
static inline void crypto_free_ablkcipher(struct crypto_ablkcipher *tfm)
{
crypto_free_tfm(crypto_ablkcipher_tfm(tfm));
}
/**
* crypto_has_ablkcipher() - Search for the availability of an ablkcipher.
* @alg_name: is the cra_name / name or cra_driver_name / driver name of the
* ablkcipher
* @type: specifies the type of the cipher
* @mask: specifies the mask for the cipher
*
* Return: true when the ablkcipher is known to the kernel crypto API; false
* otherwise
*/
static inline int crypto_has_ablkcipher(const char *alg_name, u32 type,
u32 mask)
{
@ -848,12 +906,31 @@ static inline struct ablkcipher_tfm *crypto_ablkcipher_crt(
return &crypto_ablkcipher_tfm(tfm)->crt_ablkcipher;
}
/**
* crypto_ablkcipher_ivsize() - obtain IV size
* @tfm: cipher handle
*
* The size of the IV for the ablkcipher 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_ablkcipher_ivsize(
struct crypto_ablkcipher *tfm)
{
return crypto_ablkcipher_crt(tfm)->ivsize;
}
/**
* crypto_ablkcipher_blocksize() - obtain block size of cipher
* @tfm: cipher handle
*
* The block size for the ablkcipher 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_ablkcipher_blocksize(
struct crypto_ablkcipher *tfm)
{
@ -883,6 +960,22 @@ static inline void crypto_ablkcipher_clear_flags(struct crypto_ablkcipher *tfm,
crypto_tfm_clear_flags(crypto_ablkcipher_tfm(tfm), flags);
}
/**
* crypto_ablkcipher_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 ablkcipher 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
*/
static inline int crypto_ablkcipher_setkey(struct crypto_ablkcipher *tfm,
const u8 *key, unsigned int keylen)
{
@ -891,12 +984,32 @@ static inline int crypto_ablkcipher_setkey(struct crypto_ablkcipher *tfm,
return crt->setkey(crt->base, key, keylen);
}
/**
* crypto_ablkcipher_reqtfm() - obtain cipher handle from request
* @req: ablkcipher_request out of which the cipher handle is to be obtained
*
* Return the crypto_ablkcipher handle when furnishing an ablkcipher_request
* data structure.
*
* Return: crypto_ablkcipher handle
*/
static inline struct crypto_ablkcipher *crypto_ablkcipher_reqtfm(
struct ablkcipher_request *req)
{
return __crypto_ablkcipher_cast(req->base.tfm);
}
/**
* crypto_ablkcipher_encrypt() - encrypt plaintext
* @req: reference to the ablkcipher_request handle that holds all information
* needed to perform the cipher operation
*
* Encrypt plaintext data using the ablkcipher_request handle. That data
* structure and how it is filled with data is discussed with the
* ablkcipher_request_* functions.
*
* Return: 0 if the cipher operation was successful; < 0 if an error occurred
*/
static inline int crypto_ablkcipher_encrypt(struct ablkcipher_request *req)
{
struct ablkcipher_tfm *crt =
@ -904,6 +1017,17 @@ static inline int crypto_ablkcipher_encrypt(struct ablkcipher_request *req)
return crt->encrypt(req);
}
/**
* crypto_ablkcipher_decrypt() - decrypt ciphertext
* @req: reference to the ablkcipher_request handle that holds all information
* needed to perform the cipher operation
*
* Decrypt ciphertext data using the ablkcipher_request handle. That data
* structure and how it is filled with data is discussed with the
* ablkcipher_request_* functions.
*
* Return: 0 if the cipher operation was successful; < 0 if an error occurred
*/
static inline int crypto_ablkcipher_decrypt(struct ablkcipher_request *req)
{
struct ablkcipher_tfm *crt =
@ -911,12 +1035,37 @@ static inline int crypto_ablkcipher_decrypt(struct ablkcipher_request *req)
return crt->decrypt(req);
}
/**
* DOC: Asynchronous Cipher Request Handle
*
* The ablkcipher_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 ablkcipher_request instances), pointer
* to plaintext and ciphertext, asynchronous callback function, etc. It acts
* as a handle to the ablkcipher_request_* API calls in a similar way as
* ablkcipher handle to the crypto_ablkcipher_* API calls.
*/
/**
* crypto_ablkcipher_reqsize() - obtain size of the request data structure
* @tfm: cipher handle
*
* Return: number of bytes
*/
static inline unsigned int crypto_ablkcipher_reqsize(
struct crypto_ablkcipher *tfm)
{
return crypto_ablkcipher_crt(tfm)->reqsize;
}
/**
* ablkcipher_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 ablkcipher handle in the request
* data structure with a different one.
*/
static inline void ablkcipher_request_set_tfm(
struct ablkcipher_request *req, struct crypto_ablkcipher *tfm)
{
@ -929,6 +1078,18 @@ static inline struct ablkcipher_request *ablkcipher_request_cast(
return container_of(req, struct ablkcipher_request, base);
}
/**
* ablkcipher_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 ablkcipher
* encrypt and decrypt API calls. During the allocation, the provided ablkcipher
* handle is registered in the request data structure.
*
* Return: allocated request handle in case of success; IS_ERR() is true in case
* of an error, PTR_ERR() returns the error code.
*/
static inline struct ablkcipher_request *ablkcipher_request_alloc(
struct crypto_ablkcipher *tfm, gfp_t gfp)
{
@ -943,11 +1104,40 @@ static inline struct ablkcipher_request *ablkcipher_request_alloc(
return req;
}
/**
* ablkcipher_request_free() - zeroize and free request data structure
* @req: request data structure cipher handle to be freed
*/
static inline void ablkcipher_request_free(struct ablkcipher_request *req)
{
kzfree(req);
}
/**
* ablkcipher_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 ablkcipher_request handle and
* must comply with the following template:
*
* void callback_function(struct crypto_async_request *req, int error)
*/
static inline void ablkcipher_request_set_callback(
struct ablkcipher_request *req,
u32 flags, crypto_completion_t compl, void *data)
@ -957,6 +1147,22 @@ static inline void ablkcipher_request_set_callback(
req->base.flags = flags;
}
/**
* ablkcipher_request_set_crypt() - set data buffers
* @req: request handle
* @src: source scatter / gather list
* @dst: destination scatter / gather list
* @nbytes: number of bytes to process from @src
* @iv: IV for the cipher operation which must comply with the IV size defined
* by crypto_ablkcipher_ivsize
*
* This function allows setting of the source data and destination data
* scatter / gather lists.
*
* 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.
*/
static inline void ablkcipher_request_set_crypt(
struct ablkcipher_request *req,
struct scatterlist *src, struct scatterlist *dst,