crypto: af_alg - properly label AF_ALG socket

Th AF_ALG socket was missing a security label (e.g. SELinux)
which means that socket was in "unlabeled" state.

This was recently demonstrated in the cryptsetup package
(cryptsetup v1.6.5 and later.)
See https://bugzilla.redhat.com/show_bug.cgi?id=1115120

This patch clones the sock's label from the parent sock
and resolves the issue (similar to AF_BLUETOOTH protocol family).

Cc: stable@vger.kernel.org
Signed-off-by: Milan Broz <gmazyland@gmail.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/af_alg.c

@@ -21,6 +21,7 @@
 #include <linux/module.h>
 #include <linux/net.h>
 #include <linux/rwsem.h>
+#include <linux/security.h>
 
 struct alg_type_list {
 	const struct af_alg_type *type;
@@ -243,6 +244,7 @@ int af_alg_accept(struct sock *sk, struct socket *newsock)
 
 	sock_init_data(newsock, sk2);
 	sock_graft(sk2, newsock);
+	security_sk_clone(sk, sk2);
 
 	err = type->accept(ask->private, sk2);
 	if (err) {