netfilter: nf_tables: report EOPNOTSUPP on unsupported flags/object type

EINVAL should be used for malformed netlink messages. New userspace
utility and old kernels might easily result in EINVAL when exercising
new set features, which is misleading.

Fixes: 8aeff920 ("netfilter: nf_tables: add stateful object reference to set elements")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -3963,7 +3963,7 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
 			      NFT_SET_INTERVAL | NFT_SET_TIMEOUT |
 			      NFT_SET_MAP | NFT_SET_EVAL |
 			      NFT_SET_OBJECT))
-			return -EINVAL;
+			return -EOPNOTSUPP;
 		/* Only one of these operations is supported */
 		if ((flags & (NFT_SET_MAP | NFT_SET_OBJECT)) ==
 			     (NFT_SET_MAP | NFT_SET_OBJECT))
@@ -4001,7 +4001,7 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
 		objtype = ntohl(nla_get_be32(nla[NFTA_SET_OBJ_TYPE]));
 		if (objtype == NFT_OBJECT_UNSPEC ||
 		    objtype > NFT_OBJECT_MAX)
-			return -EINVAL;
+			return -EOPNOTSUPP;
 	} else if (flags & NFT_SET_OBJECT)
 		return -EINVAL;
 	else