Re: [PATCH 2/2] lib/digsig: Use SHA-1 library instead of crypto_shash

[Paul Menzel <pmenzel@molgen.mpg.de>]

Dear Eric,


Thank you for your patch.

Am 15.08.25 um 04:17 schrieb Eric Biggers:
> Now that a SHA-1 library API is available, use it instead of
> crypto_shash.  This is simpler and faster.
> 
> Signed-off-by: Eric Biggers <ebiggers@kernel.org>
> ---
>   lib/Kconfig  |  3 +--
>   lib/digsig.c | 46 ++++++----------------------------------------
>   2 files changed, 7 insertions(+), 42 deletions(-)
> 
> diff --git a/lib/Kconfig b/lib/Kconfig
> index c483951b624ff..e629449dd2a36 100644
> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -475,12 +475,11 @@ config MPILIB
>   	  which is used by IMA/EVM digital signature extension.
>   
>   config SIGNATURE
>   	tristate
>   	depends on KEYS
> -	select CRYPTO
> -	select CRYPTO_SHA1
> +	select CRYPTO_LIB_SHA1
>   	select MPILIB
>   	help
>   	  Digital signature verification. Currently only RSA is supported.
>   	  Implementation is done using GnuPG MPI library
>   
> diff --git a/lib/digsig.c b/lib/digsig.c
> index 04b5e55ed95f5..5ddcc52f76863 100644
> --- a/lib/digsig.c
> +++ b/lib/digsig.c
> @@ -16,19 +16,15 @@
>   
>   #include <linux/err.h>
>   #include <linux/module.h>
>   #include <linux/slab.h>
>   #include <linux/key.h>
> -#include <linux/crypto.h>
> -#include <crypto/hash.h>
>   #include <crypto/sha1.h>
>   #include <keys/user-type.h>
>   #include <linux/mpi.h>
>   #include <linux/digsig.h>
>   
> -static struct crypto_shash *shash;
> -
>   static const char *pkcs_1_v1_5_decode_emsa(const unsigned char *msg,
>   						unsigned long  msglen,
>   						unsigned long  modulus_bitlen,
>   						unsigned long *outlen)
>   {
> @@ -197,16 +193,16 @@ static int digsig_verify_rsa(struct key *key,
>    *
>    */
>   int digsig_verify(struct key *keyring, const char *sig, int siglen,
>   						const char *data, int datalen)
>   {
> -	int err = -ENOMEM;
>   	struct signature_hdr *sh = (struct signature_hdr *)sig;
> -	struct shash_desc *desc = NULL;
> +	struct sha1_ctx ctx;
>   	unsigned char hash[SHA1_DIGEST_SIZE];
>   	struct key *key;
>   	char name[20];
> +	int err;
>   
>   	if (siglen < sizeof(*sh) + 2)
>   		return -EINVAL;
>   
>   	if (sh->algo != PUBKEY_ALGO_RSA)
> @@ -229,51 +225,21 @@ int digsig_verify(struct key *keyring, const char *sig, int siglen,
>   	if (IS_ERR(key)) {
>   		pr_err("key not found, id: %s\n", name);
>   		return PTR_ERR(key);
>   	}
>   
> -	desc = kzalloc(sizeof(*desc) + crypto_shash_descsize(shash),
> -		       GFP_KERNEL);
> -	if (!desc)
> -		goto err;
> -
> -	desc->tfm = shash;
> -
> -	crypto_shash_init(desc);
> -	crypto_shash_update(desc, data, datalen);
> -	crypto_shash_update(desc, sig, sizeof(*sh));
> -	crypto_shash_final(desc, hash);
> -
> -	kfree(desc);
> +	sha1_init(&ctx);
> +	sha1_update(&ctx, data, datalen);
> +	sha1_update(&ctx, sig, sizeof(*sh));
> +	sha1_final(&ctx, hash);
>   
>   	/* pass signature mpis address */
>   	err = digsig_verify_rsa(key, sig + sizeof(*sh), siglen - sizeof(*sh),
>   			     hash, sizeof(hash));
>   
> -err:
>   	key_put(key);
>   
>   	return err ? -EINVAL : 0;
>   }
>   EXPORT_SYMBOL_GPL(digsig_verify);
>   
> -static int __init digsig_init(void)
> -{
> -	shash = crypto_alloc_shash("sha1", 0, 0);
> -	if (IS_ERR(shash)) {
> -		pr_err("shash allocation failed\n");
> -		return  PTR_ERR(shash);
> -	}
> -
> -	return 0;
> -
> -}
> -
> -static void __exit digsig_cleanup(void)
> -{
> -	crypto_free_shash(shash);
> -}
> -
> -module_init(digsig_init);
> -module_exit(digsig_cleanup);
> -
>   MODULE_LICENSE("GPL");

Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>


Kind regards,

Paul