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>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
[kamal: plus bwh http://article.gmane.org/gmane.linux.kernel.stable/169083]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

crypto/ablkcipher.c

@@ -375,6 +375,7 @@ 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;
 }
@@ -456,6 +457,7 @@ static int crypto_init_givcipher_ops(struct crypto_tfm *tfm, u32 type,
 	crt->givdecrypt = alg->givdecrypt ?: no_givdecrypt;
 	crt->base = __crypto_ablkcipher_cast(tfm);
 	crt->ivsize = alg->ivsize;
+	crt->has_setkey = alg->max_keysize;
 
 	return 0;
 }

crypto/blkcipher.c

@@ -471,6 +471,7 @@ static int crypto_init_blkcipher_ops_async(struct crypto_tfm *tfm)
 	}
 	crt->base = __crypto_ablkcipher_cast(tfm);
 	crt->ivsize = alg->ivsize;
+	crt->has_setkey = alg->max_keysize;
 
 	return 0;
 }

include/linux/crypto.h

@@ -594,6 +594,7 @@ struct ablkcipher_tfm {
 
 	unsigned int ivsize;
 	unsigned int reqsize;
+	bool has_setkey;
 };
 
 struct aead_tfm {
@@ -997,6 +998,13 @@ 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;
+}
+
 /**
  * crypto_ablkcipher_reqtfm() - obtain cipher handle from request
  * @req: ablkcipher_request out of which the cipher handle is to be obtained