2023-10-29 05:04:11

by Eric Biggers

[permalink] [raw]
Subject: [PATCH] ubifs: use crypto_shash_tfm_digest() in ubifs_hmac_wkm()

From: Eric Biggers <[email protected]>

Simplify ubifs_hmac_wkm() by using crypto_shash_tfm_digest() instead of
an alloc+init+update+final sequence. This should also improve
performance.

Signed-off-by: Eric Biggers <[email protected]>
---
fs/ubifs/auth.c | 19 ++-----------------
1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/fs/ubifs/auth.c b/fs/ubifs/auth.c
index e564d5ff8781..4add4a4f0720 100644
--- a/fs/ubifs/auth.c
+++ b/fs/ubifs/auth.c
@@ -501,42 +501,27 @@ int __ubifs_shash_copy_state(const struct ubifs_info *c, struct shash_desc *src,
*
* This function creates a HMAC of a well known message. This is used
* to check if the provided key is suitable to authenticate a UBIFS
* image. This is only a convenience to the user to provide a better
* error message when the wrong key is provided.
*
* This function returns 0 for success or a negative error code otherwise.
*/
int ubifs_hmac_wkm(struct ubifs_info *c, u8 *hmac)
{
- SHASH_DESC_ON_STACK(shash, c->hmac_tfm);
- int err;
const char well_known_message[] = "UBIFS";

if (!ubifs_authenticated(c))
return 0;

- shash->tfm = c->hmac_tfm;
-
- err = crypto_shash_init(shash);
- if (err)
- return err;
-
- err = crypto_shash_update(shash, well_known_message,
- sizeof(well_known_message) - 1);
- if (err < 0)
- return err;
-
- err = crypto_shash_final(shash, hmac);
- if (err)
- return err;
- return 0;
+ return crypto_shash_tfm_digest(c->hmac_tfm, well_known_message,
+ sizeof(well_known_message) - 1, hmac);
}

/*
* ubifs_hmac_zero - test if a HMAC is zero
* @c: UBIFS file-system description object
* @hmac: the HMAC to test
*
* This function tests if a HMAC is zero and returns true if it is
* and false otherwise.
*/

base-commit: 2af9b20dbb39f6ebf9b9b6c090271594627d818e
--
2.42.0


2023-10-31 04:12:24

by Zhihao Cheng

[permalink] [raw]
Subject: Re: [PATCH] ubifs: use crypto_shash_tfm_digest() in ubifs_hmac_wkm()

?? 2023/10/29 13:03, Eric Biggers ะด??:
> From: Eric Biggers <[email protected]>
>
> Simplify ubifs_hmac_wkm() by using crypto_shash_tfm_digest() instead of
> an alloc+init+update+final sequence. This should also improve
> performance.
>
> Signed-off-by: Eric Biggers <[email protected]>
> ---
> fs/ubifs/auth.c | 19 ++-----------------
> 1 file changed, 2 insertions(+), 17 deletions(-)

Tested-by: Zhihao Cheng <[email protected]>

Time cost of ubifs_hmac_wkm(unit: us):

Before: 381~1634

After:278~1539

>
> diff --git a/fs/ubifs/auth.c b/fs/ubifs/auth.c
> index e564d5ff8781..4add4a4f0720 100644
> --- a/fs/ubifs/auth.c
> +++ b/fs/ubifs/auth.c
> @@ -501,42 +501,27 @@ int __ubifs_shash_copy_state(const struct ubifs_info *c, struct shash_desc *src,
> *
> * This function creates a HMAC of a well known message. This is used
> * to check if the provided key is suitable to authenticate a UBIFS
> * image. This is only a convenience to the user to provide a better
> * error message when the wrong key is provided.
> *
> * This function returns 0 for success or a negative error code otherwise.
> */
> int ubifs_hmac_wkm(struct ubifs_info *c, u8 *hmac)
> {
> - SHASH_DESC_ON_STACK(shash, c->hmac_tfm);
> - int err;
> const char well_known_message[] = "UBIFS";
>
> if (!ubifs_authenticated(c))
> return 0;
>
> - shash->tfm = c->hmac_tfm;
> -
> - err = crypto_shash_init(shash);
> - if (err)
> - return err;
> -
> - err = crypto_shash_update(shash, well_known_message,
> - sizeof(well_known_message) - 1);
> - if (err < 0)
> - return err;
> -
> - err = crypto_shash_final(shash, hmac);
> - if (err)
> - return err;
> - return 0;
> + return crypto_shash_tfm_digest(c->hmac_tfm, well_known_message,
> + sizeof(well_known_message) - 1, hmac);
> }
>
> /*
> * ubifs_hmac_zero - test if a HMAC is zero
> * @c: UBIFS file-system description object
> * @hmac: the HMAC to test
> *
> * This function tests if a HMAC is zero and returns true if it is
> * and false otherwise.
> */
>
> base-commit: 2af9b20dbb39f6ebf9b9b6c090271594627d818e