Commit 822a98b8 authored by Eric Biggers's avatar Eric Biggers Committed by Herbert Xu
Browse files

crypto: hash - introduce crypto_shash_tfm_digest() 



Currently the simplest use of the shash API is to use
crypto_shash_digest() to digest a whole buffer.  However, this still
requires allocating a hash descriptor (struct shash_desc).  Many users
don't really want to preallocate one and instead just use a one-off
descriptor on the stack like the following:

	{
		SHASH_DESC_ON_STACK(desc, tfm);
		int err;

		desc->tfm = tfm;

		err = crypto_shash_digest(desc, data, len, out);

		shash_desc_zero(desc);
	}

Wrap this in a new helper function crypto_shash_tfm_digest() that can be
used instead of the above.

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 13855fd8

crypto/shash.c

+16 −0
Original line number Diff line number Diff line
@@ -206,6 +206,22 @@ int crypto_shash_digest(struct shash_desc *desc, const u8 *data, 
}

EXPORT_SYMBOL_GPL(crypto_shash_digest);



int crypto_shash_tfm_digest(struct crypto_shash *tfm, const u8 *data,

			    unsigned int len, u8 *out)

{

	SHASH_DESC_ON_STACK(desc, tfm);

	int err;



	desc->tfm = tfm;



	err = crypto_shash_digest(desc, data, len, out);



	shash_desc_zero(desc);



	return err;

}

EXPORT_SYMBOL_GPL(crypto_shash_tfm_digest);



static int shash_default_export(struct shash_desc *desc, void *out)

{

	memcpy(out, shash_desc_ctx(desc), crypto_shash_descsize(desc->tfm));

include/crypto/hash.h

+19 −0
Original line number Diff line number Diff line
@@ -855,6 +855,25 @@ int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key, 
int crypto_shash_digest(struct shash_desc *desc, const u8 *data,

			unsigned int len, u8 *out);



/**

 * crypto_shash_tfm_digest() - calculate message digest for buffer

 * @tfm: hash transformation object

 * @data: see crypto_shash_update()

 * @len: see crypto_shash_update()

 * @out: see crypto_shash_final()

 *

 * This is a simplified version of crypto_shash_digest() for users who don't

 * want to allocate their own hash descriptor (shash_desc).  Instead,

 * crypto_shash_tfm_digest() takes a hash transformation object (crypto_shash)

 * directly, and it allocates a hash descriptor on the stack internally.

 * Note that this stack allocation may be fairly large.

 *

 * Context: Any context.

 * Return: 0 on success; < 0 if an error occurred.

 */

int crypto_shash_tfm_digest(struct crypto_shash *tfm, 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

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