netfilter: nf_nat: place conntrack in source hash after SNAT is done

If SNAT isn't done, the wrong info maybe got by the other cts.

As the filter table is after DNAT table, the packets dropped in filter
table also bother bysource hash table.

Signed-off-by: Changli Gao <[e-mail]>
Signed-off-by: Patrick McHardy <[e-mail]>

net/ipv4/netfilter/nf_nat_core.c

···
 	   manips not an issue.  */
 	if (maniptype == IP_NAT_MANIP_SRC &&
 	    !(range->flags & IP_NAT_RANGE_PROTO_RANDOM)) {
-		if (find_appropriate_src(net, zone, orig_tuple, tuple, range)) {
+		/* try the original tuple first */
+		if (in_range(orig_tuple, range)) {
+			if (!nf_nat_used_tuple(orig_tuple, ct)) {
+				*tuple = *orig_tuple;
+				return;
+			}
+		} else if (find_appropriate_src(net, zone, orig_tuple, tuple,
+			   range)) {
 			pr_debug("get_unique_tuple: Found current src map\n");
 			if (!nf_nat_used_tuple(tuple, ct))
 				return;
···
 	struct net *net = nf_ct_net(ct);
 	struct nf_conntrack_tuple curr_tuple, new_tuple;
 	struct nf_conn_nat *nat;
-	int have_to_hash = !(ct->status & IPS_NAT_DONE_MASK);
 
 	/* nat helper or nfctnetlink also setup binding */
 	nat = nfct_nat(ct);
···
 			ct->status |= IPS_DST_NAT;
 	}
 
-	/* Place in source hash if this is the first time. */
-	if (have_to_hash) {
+	if (maniptype == IP_NAT_MANIP_SRC) {
 		unsigned int srchash;
 
 		srchash = hash_by_src(net, nf_ct_zone(ct),
···
 	if (nat == NULL || nat->ct == NULL)
 		return;
 
-	NF_CT_ASSERT(nat->ct->status & IPS_NAT_DONE_MASK);
+	NF_CT_ASSERT(nat->ct->status & IPS_SRC_NAT_DONE);
 
 	spin_lock_bh(&nf_nat_lock);
 	hlist_del_rcu(&nat->bysource);
···
 	struct nf_conn_nat *old_nat = old;
 	struct nf_conn *ct = old_nat->ct;
 
-	if (!ct || !(ct->status & IPS_NAT_DONE_MASK))
+	if (!ct || !(ct->status & IPS_SRC_NAT_DONE))
 		return;
 
 	spin_lock_bh(&nf_nat_lock);
-	new_nat->ct = ct;
 	hlist_replace_rcu(&old_nat->bysource, &new_nat->bysource);
 	spin_unlock_bh(&nf_nat_lock);
 }