netfilter: nf_nat: handle NF_DROP from nfnetlink_parse_nat_setup()

nf_nat_setup_info() returns NF_* verdicts, so convert them to error
codes that is what ctnelink expects. This has passed overlook without
having any impact since this nf_nat_setup_info() has always returned
NF_ACCEPT so far. Since 870190a9ec90 ("netfilter: nat: convert nat bysrc
hash to rhashtable"), this is problem.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_nat_core.c

@@ -807,7 +807,7 @@ nfnetlink_parse_nat_setup(struct nf_conn *ct,
 	if (err < 0)
 		return err;
 
-	return nf_nat_setup_info(ct, &range, manip);
+	return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0;
 }
 #else
 static int