[PATCH] ubifs: use crypto_shash_tfm_digest() in ubifs_hmac_wkm()

[Eric Biggers]

From: Eric Biggers <ebiggers at google.com>

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 <ebiggers at google.com>
---
 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