crypto: hash - annotate algorithms taking optional key

We need to consistently enforce that keyed hashes cannot be used without
setting the key.  To do this we need a reliable way to determine whether
a given hash algorithm is keyed or not.  AF_ALG currently does this by
checking for the presence of a ->setkey() method.  However, this is
actually slightly broken because the CRC-32 algorithms implement
->setkey() but can also be used without a key.  (The CRC-32 "key" is not
actually a cryptographic key but rather represents the initial state.
If not overridden, then a default initial state is used.)

Prepare to fix this by introducing a flag CRYPTO_ALG_OPTIONAL_KEY which
indicates that the algorithm has a ->setkey() method, but it is not
required to be called.  Then set it on all the CRC-32 algorithms.

The same also applies to the Adler-32 implementation in Lustre.

Also, the cryptd and mcryptd templates have to pass through the flag
from their underlying algorithm.

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

drivers/crypto/stm32/stm32_crc32.c

@@ -208,6 +208,7 @@ static struct shash_alg algs[] = {
 			.cra_name               = "crc32",
 			.cra_driver_name        = DRIVER_NAME,
 			.cra_priority           = 200,
+			.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,
 			.cra_blocksize          = CHKSUM_BLOCK_SIZE,
 			.cra_alignmask          = 3,
 			.cra_ctxsize            = sizeof(struct stm32_crc_ctx),
@@ -229,6 +230,7 @@ static struct shash_alg algs[] = {
 			.cra_name               = "crc32c",
 			.cra_driver_name        = DRIVER_NAME,
 			.cra_priority           = 200,
+			.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,
 			.cra_blocksize          = CHKSUM_BLOCK_SIZE,
 			.cra_alignmask          = 3,
 			.cra_ctxsize            = sizeof(struct stm32_crc_ctx),