[PATCH v3 nf] netfilter: nf_flow_table: do not use deleted CT's flow offload

[Taehee Yoo <ap420073@gmail.com>]

flow offload of CT can be deleted by the masquerade module. then,
flow offload should be deleted too. but GC and data-path of flow offload
do not check CT's status. hence they will be removed only by the timeout.

GC and data-path routine will check ct->status.
If IPS_DYING_BIT is set, GC will delete CT and data-path routine
do not use it.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
---

v2 -> v3 : use nf_ct_is_dying().
v1 -> v2 : use IPS_DYING_BIT instead of ct->ct_general.use refcnt.

 net/netfilter/nf_flow_table_core.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
index 7aabfd4b1e50..6477a5cbaaa5 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -232,6 +232,7 @@ flow_offload_lookup(struct nf_flowtable *flow_table,
 {
 	struct flow_offload_tuple_rhash *tuplehash;
 	struct flow_offload *flow;
+	struct flow_offload_entry *e;
 	int dir;
 
 	tuplehash = rhashtable_lookup(&flow_table->rhashtable, tuple,
@@ -244,6 +245,10 @@ flow_offload_lookup(struct nf_flowtable *flow_table,
 	if (flow->flags & (FLOW_OFFLOAD_DYING | FLOW_OFFLOAD_TEARDOWN))
 		return NULL;
 
+	e = container_of(flow, struct flow_offload_entry, flow);
+	if (unlikely(nf_ct_is_dying(e->ct)))
+		return NULL;
+
 	return tuplehash;
 }
 EXPORT_SYMBOL_GPL(flow_offload_lookup);
@@ -290,8 +295,10 @@ static inline bool nf_flow_has_expired(const struct flow_offload *flow)
 static void nf_flow_offload_gc_step(struct flow_offload *flow, void *data)
 {
 	struct nf_flowtable *flow_table = data;
+	struct flow_offload_entry *e;
 
-	if (nf_flow_has_expired(flow) ||
+	e = container_of(flow, struct flow_offload_entry, flow);
+	if (nf_flow_has_expired(flow) || nf_ct_is_dying(e->ct) ||
 	    (flow->flags & (FLOW_OFFLOAD_DYING | FLOW_OFFLOAD_TEARDOWN)))
 		flow_offload_del(flow_table, flow);
 }
-- 
2.17.1