[PATCH] crypto: shash - Allow cloning on algorithms with no init_tfm

[Herbert Xu]

On Fri, May 19, 2023 at 10:54:11AM +0200, Ard Biesheuvel wrote:
>
> Does this imply that the cmac-aes-ce and cmac-aes-neon implementations
> for arm64 need a similar treatment?

Good catch.  Since these don't have init functions we can deal
with them at a higher level:

---8<---
Some shash algorithms are so simple that they don't have an init_tfm
function.  These can be cloned trivially.  Check this before failing
in crypto_clone_shash.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

diff --git a/crypto/shash.c b/crypto/shash.c
index 717b42df3495..1fadb6b59bdc 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -597,7 +597,7 @@ struct crypto_shash *crypto_clone_shash(struct crypto_shash *hash)
 		return hash;
 	}
 
-	if (!alg->clone_tfm)
+	if (!alg->clone_tfm && (alg->init_tfm || alg->base.cra_init))
 		return ERR_PTR(-ENOSYS);
 
 	nhash = crypto_clone_tfm(&crypto_shash_type, tfm);
@@ -606,10 +606,12 @@ struct crypto_shash *crypto_clone_shash(struct crypto_shash *hash)
 
 	nhash->descsize = hash->descsize;
 
-	err = alg->clone_tfm(nhash, hash);
-	if (err) {
-		crypto_free_shash(nhash);
-		return ERR_PTR(err);
+	if (alg->clone_tfm) {
+		err = alg->clone_tfm(nhash, hash);
+		if (err) {
+			crypto_free_shash(nhash);
+			return ERR_PTR(err);
+		}
 	}
 
 	return nhash;
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt