path: root/include/crypto/hash.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Hash: Hash algorithms under the crypto API
 * 
 * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
 */

#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;
};

/**
 * 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.
 * @init_tfm: 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_tfm: Deinitialize the cryptographic transformation object.
 *	      This is a counterpart to @init_tfm, used to remove
 *	      various changes set in @init_tfm.
 * @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);
	int (*init_tfm)(struct crypto_ahash *tfm);
	void (*exit_tfm)(struct crypto_ahash *tfm);

	struct hash_alg_common halg;
};

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

#define HASH_MAX_DIGESTSIZE	 64

/*
 * Worst case is hmac(sha3-224-generic).  Its context is a nested 'shash_desc'
 * containing a 'struct sha3_state'.
 */
#define HASH_MAX_DESCSIZE	(sizeof(struct shash_desc) + 360)

#define HASH_MAX_STATESIZE	512

#define SHASH_DESC_ON_STACK(shash, ctx)				  \
	char __##shash##_desc[sizeof(struct shash_desc) +	  \
		HASH_MAX_DESCSIZE] 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
 * @init_tfm: 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_tfm: Deinitialize the cryptographic transformation object.
 *	      This is a counterpart to @init_tfm, used to remove
 *	      various changes set in @init_tfm.
 * @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