crypto: algapi - use common mechanism for inheriting flags

The flag CRYPTO_ALG_ASYNC is "inherited" in the sense that when a
template is instantiated, the template will have CRYPTO_ALG_ASYNC set if
any of the algorithms it uses has CRYPTO_ALG_ASYNC set.

We'd like to add a second flag (CRYPTO_ALG_ALLOCATES_MEMORY) that gets
"inherited" in the same way.  This is difficult because the handling of
CRYPTO_ALG_ASYNC is hardcoded everywhere.  Address this by:

  - Add CRYPTO_ALG_INHERITED_FLAGS, which contains the set of flags that
    have these inheritance semantics.

  - Add crypto_algt_inherited_mask(), for use by template ->create()
    methods.  It returns any of these flags that the user asked to be
    unset and thus must be passed in the 'mask' to crypto_grab_*().

  - Also modify crypto_check_attr_type() to handle computing the 'mask'
    so that most templates can just use this.

  - Make crypto_grab_*() propagate these flags to the template instance
    being created so that templates don't have to do this themselves.

Make crypto/simd.c propagate these flags too, since it "wraps" another
algorithm, similar to a template.

Based on a patch by Mikulas Patocka <mpatocka@redhat.com>
(https://lore.kernel.org/r/alpine.LRH.2.02.2006301414580.30526@file01.intranet.prod.int.rdu2.redhat.com).

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 5 insertions, 10 deletions

diff --git a/crypto/skcipher.c b/crypto/skcipher.c
index 7221def7b9a7..3b93a74ad124 100644
--- a/crypto/skcipher.c
+++ b/crypto/skcipher.c
@@ -934,22 +934,17 @@ static void skcipher_free_instance_simple(struct skcipher_instance *inst)
 struct skcipher_instance *skcipher_alloc_instance_simple(
 	struct crypto_template *tmpl, struct rtattr **tb)
 {
-	struct crypto_attr_type *algt;
 	u32 mask;
 	struct skcipher_instance *inst;
 	struct crypto_cipher_spawn *spawn;
 	struct crypto_alg *cipher_alg;
 	int err;
 
-	algt = crypto_get_attr_type(tb);
-	if (IS_ERR(algt))
-		return ERR_CAST(algt);
-
-	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
-		return ERR_PTR(-EINVAL);
-
-	mask = crypto_requires_off(algt->type, algt->mask,
-				   CRYPTO_ALG_NEED_FALLBACK);
+	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
+	if (err)
+		return ERR_PTR(err);
+	mask |= crypto_requires_off(crypto_get_attr_type(tb),
+				    CRYPTO_ALG_NEED_FALLBACK);
 
 	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 	if (!inst)