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, 3 insertions, 2 deletions

diff --git a/crypto/cmac.c b/crypto/cmac.c
index 143a6544c873..df36be1efb81 100644
--- a/crypto/cmac.c
+++ b/crypto/cmac.c
@@ -225,9 +225,10 @@ static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb)
 	struct crypto_cipher_spawn *spawn;
 	struct crypto_alg *alg;
 	unsigned long alignmask;
+	u32 mask;
 	int err;
 
-	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
+	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
 	if (err)
 		return err;
 
@@ -237,7 +238,7 @@ static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb)
 	spawn = shash_instance_ctx(inst);
 
 	err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),
-				 crypto_attr_alg_name(tb[1]), 0, 0);
+				 crypto_attr_alg_name(tb[1]), 0, mask);
 	if (err)
 		goto err_free_inst;
 	alg = crypto_spawn_cipher_alg(spawn);