[CRYPTO] api: Added crypto_alloc_base

Up until now all crypto transforms have been of the same type, struct
crypto_tfm, regardless of whether they are ciphers, digests, or other
types.  As a result of that, we check the types at run-time before
each crypto operation.

This is rather cumbersome.  We could instead use different C types for
each crypto type to ensure that the correct types are used at compile
time.  That is, we would have crypto_cipher/crypto_digest instead of
just crypto_tfm.  The appropriate type would then be required for the
actual operations such as crypto_digest_digest.

Now that we have the type/mask fields when looking up algorithms, it
is easy to request for an algorithm of the precise type that the user
wants.  However, crypto_alloc_tfm currently does not expose these new
attributes.

This patch introduces the function crypto_alloc_base which will carry
these new parameters.  It will be renamed to crypto_alloc_tfm once
all existing users have been converted.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 3 insertions, 11 deletions

diff --git a/include/linux/crypto.h b/include/linux/crypto.h
index 530dc4b..6847ab0 100644
--- a/include/linux/crypto.h
+++ b/include/linux/crypto.h
@@ -194,8 +194,8 @@ static inline int crypto_alg_available(const char *name, u32 flags)
 
 /*
  * Transforms: user-instantiated objects which encapsulate algorithms
- * and core processing logic.  Managed via crypto_alloc_tfm() and
- * crypto_free_tfm(), as well as the various helpers below.
+ * and core processing logic.  Managed via crypto_alloc_*() and
+ * crypto_free_*(), as well as the various helpers below.
  */
 
 struct cipher_tfm {
@@ -278,16 +278,8 @@ struct crypto_attr_alg {
  * Transform user interface.
  */
  
-/*
- * crypto_alloc_tfm() will first attempt to locate an already loaded algorithm.
- * If that fails and the kernel supports dynamically loadable modules, it
- * will then attempt to load a module of the same name or alias.  A refcount
- * is grabbed on the algorithm which is then associated with the new transform.
- *
- * crypto_free_tfm() frees up the transform and any associated resources,
- * then drops the refcount on the associated algorithm.
- */
 struct crypto_tfm *crypto_alloc_tfm(const char *alg_name, u32 tfm_flags);
+struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask);
 void crypto_free_tfm(struct crypto_tfm *tfm);
 
 /*