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crypto: hash - introduce crypto_shash_tfm_digest()

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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: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers 2020-05-01 22:31:03 -07:00 committed by Herbert Xu
parent 13855fd8ce
commit 822a98b862
2 changed files with 35 additions and 0 deletions
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16
crypto/shash.c
View file

@ -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));

19
include/crypto/hash.h
View file

@ -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