crypto: skcipher - Add crypto_skcipher_has_setkey

commit a1383cd8 upstream.

This patch adds a way for skcipher users to determine whether a key
is required by a transform.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
[bwh: Backported to 3.2: add to ablkcipher API instead]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

crypto/ablkcipher.c

@@ -379,6 +379,7 @@ static int crypto_init_ablkcipher_ops(struct crypto_tfm *tfm, u32 type,
 	}
 	crt->base = __crypto_ablkcipher_cast(tfm);
 	crt->ivsize = alg->ivsize;
+	crt->has_setkey = alg->max_keysize;
 
 	return 0;
 }

include/linux/crypto.h

@@ -346,6 +346,7 @@ struct ablkcipher_tfm {
 
 	unsigned int ivsize;
 	unsigned int reqsize;
+	bool has_setkey;
 };
 
 struct aead_tfm {
@@ -656,6 +657,13 @@ static inline int crypto_ablkcipher_setkey(struct crypto_ablkcipher *tfm,
 	return crt->setkey(crt->base, key, keylen);
 }
 
+static inline bool crypto_ablkcipher_has_setkey(struct crypto_ablkcipher *tfm)
+{
+	struct ablkcipher_tfm *crt = crypto_ablkcipher_crt(tfm);
+
+	return crt->has_setkey;
+}
+
 static inline struct crypto_ablkcipher *crypto_ablkcipher_reqtfm(
 	struct ablkcipher_request *req)
 {