netfilter: nf_tables: disallow anonymous set with timeout flag

Anonymous sets are never used with timeout from userspace, reject this.
Exception to this rule is NFT_SET_EVAL to ensure legacy meters still work.

Cc: stable@vger.kernel.org
Fixes: 761da293 ("netfilter: nf_tables: add set timeout API support")
Reported-by: lonial con <kongln9170@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -5001,6 +5001,9 @@ static int nf_tables_newset(struct sk_buff *skb, const struct nfnl_info *info,
 		if ((flags & (NFT_SET_EVAL | NFT_SET_OBJECT)) ==
 			     (NFT_SET_EVAL | NFT_SET_OBJECT))
 			return -EOPNOTSUPP;
+		if ((flags & (NFT_SET_ANONYMOUS | NFT_SET_TIMEOUT | NFT_SET_EVAL)) ==
+			     (NFT_SET_ANONYMOUS | NFT_SET_TIMEOUT))
+			return -EOPNOTSUPP;
 	}
 
 	desc.dtype = 0;