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, 16 insertions, 7 deletions

diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index 00a9cf98debe..da64c37482b4 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -116,7 +116,7 @@ struct crypto_tfm *crypto_spawn_tfm(struct crypto_spawn *spawn, u32 type,
 void *crypto_spawn_tfm2(struct crypto_spawn *spawn);
 
 struct crypto_attr_type *crypto_get_attr_type(struct rtattr **tb);
-int crypto_check_attr_type(struct rtattr **tb, u32 type);
+int crypto_check_attr_type(struct rtattr **tb, u32 type, u32 *mask_ret);
 const char *crypto_attr_alg_name(struct rtattr *rta);
 int crypto_attr_u32(struct rtattr *rta, u32 *num);
 int crypto_inst_setname(struct crypto_instance *inst, const char *name,
@@ -235,18 +235,27 @@ static inline struct crypto_async_request *crypto_get_backlog(
 	       container_of(queue->backlog, struct crypto_async_request, list);
 }
 
-static inline int crypto_requires_off(u32 type, u32 mask, u32 off)
+static inline u32 crypto_requires_off(struct crypto_attr_type *algt, u32 off)
 {
-	return (type ^ off) & mask & off;
+	return (algt->type ^ off) & algt->mask & off;
 }
 
 /*
- * Returns CRYPTO_ALG_ASYNC if type/mask requires the use of sync algorithms.
- * Otherwise returns zero.
+ * When an algorithm uses another algorithm (e.g., if it's an instance of a
+ * template), these are the flags that should always be set on the "outer"
+ * algorithm if any "inner" algorithm has them set.
  */
-static inline int crypto_requires_sync(u32 type, u32 mask)
+#define CRYPTO_ALG_INHERITED_FLAGS	CRYPTO_ALG_ASYNC
+
+/*
+ * Given the type and mask that specify the flags restrictions on a template
+ * instance being created, return the mask that should be passed to
+ * crypto_grab_*() (along with type=0) to honor any request the user made to
+ * have any of the CRYPTO_ALG_INHERITED_FLAGS clear.
+ */
+static inline u32 crypto_algt_inherited_mask(struct crypto_attr_type *algt)
 {
-	return crypto_requires_off(type, mask, CRYPTO_ALG_ASYNC);
+	return crypto_requires_off(algt, CRYPTO_ALG_INHERITED_FLAGS);
 }
 
 noinline unsigned long __crypto_memneq(const void *a, const void *b, size_t size);