From 822a98b862d5b511826765d64ddf18192fc5b694 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 1 May 2020 22:31:03 -0700 Subject: [PATCH] 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: Eric Biggers Signed-off-by: Herbert Xu --- crypto/shash.c | 16 ++++++++++++++++ include/crypto/hash.h | 19 +++++++++++++++++++ 2 files changed, 35 insertions(+) diff --git a/crypto/shash.c b/crypto/shash.c index c075b26c2a1d..e6a4b5f39b8c 100644 --- a/crypto/shash.c +++ b/crypto/shash.c @@ -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)); diff --git a/include/crypto/hash.h b/include/crypto/hash.h index cee446c59497..4829d2367eda 100644 --- a/include/crypto/hash.h +++ b/include/crypto/hash.h @@ -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