crypto: skcipher - Add crypto_skcipher_has_setkey

This patch adds a way for skcipher users to determine whether a key
is required by a transform.

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

crypto/skcipher.c

@@ -118,6 +118,7 @@ static int crypto_init_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
 	skcipher->decrypt = skcipher_decrypt_blkcipher;
 
 	skcipher->ivsize = crypto_blkcipher_ivsize(blkcipher);
+	skcipher->has_setkey = calg->cra_blkcipher.max_keysize;
 
 	return 0;
 }
@@ -210,6 +211,7 @@ static int crypto_init_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
 	skcipher->ivsize = crypto_ablkcipher_ivsize(ablkcipher);
 	skcipher->reqsize = crypto_ablkcipher_reqsize(ablkcipher) +
 			    sizeof(struct ablkcipher_request);
+	skcipher->has_setkey = calg->cra_ablkcipher.max_keysize;
 
 	return 0;
 }

include/crypto/skcipher.h

@@ -61,6 +61,8 @@ struct crypto_skcipher {
 	unsigned int ivsize;
 	unsigned int reqsize;
 
+	bool has_setkey;
+
 	struct crypto_tfm base;
 };
 
@@ -305,6 +307,11 @@ static inline int crypto_skcipher_setkey(struct crypto_skcipher *tfm,
 	return tfm->setkey(tfm, key, keylen);
 }
 
+static inline bool crypto_skcipher_has_setkey(struct crypto_skcipher *tfm)
+{
+	return tfm->has_setkey;
+}
+
 /**
  * crypto_skcipher_reqtfm() - obtain cipher handle from request
  * @req: skcipher_request out of which the cipher handle is to be obtained