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>

1 files changed, 3 insertions, 4 deletions

diff --git a/crypto/mcryptd.c b/crypto/mcryptd.c
index ace346b976b3..fe5129d6ff4e 100644
--- a/crypto/mcryptd.c
+++ b/crypto/mcryptd.c
@@ -516,10 +516,9 @@ static int mcryptd_create_hash(struct crypto_template *tmpl, struct rtattr **tb,
         if (err)
                 goto out_free_inst;
 
-        type = CRYPTO_ALG_ASYNC;
-        if (alg->cra_flags & CRYPTO_ALG_INTERNAL)
-                type |= CRYPTO_ALG_INTERNAL;
-        inst->alg.halg.base.cra_flags = type;
+        inst->alg.halg.base.cra_flags = CRYPTO_ALG_ASYNC |
+                (alg->cra_flags & (CRYPTO_ALG_INTERNAL |
+                                   CRYPTO_ALG_OPTIONAL_KEY));
 
         inst->alg.halg.digestsize = halg->digestsize;
         inst->alg.halg.statesize = halg->statesize;