bridge: Check if vlan filtering is enabled only once.

The bridge code checks if vlan filtering is enabled on both ingress and egress. When the state flip happens, it is possible for the bridge to currently be forwarding packets and forwarding behavior becomes non-deterministic. Bridge may drop packets on some interfaces, but not others. This patch solves this by caching the filtered state of the packet into skb_cb on ingress. The skb_cb is guaranteed to not be over-written between the time packet entres bridge forwarding path and the time it leaves it. On egress, we can then check the cached state to see if we need to apply filtering information. Signed-off-by: Vladislav Yasevich <[email protected]> Signed-off-by: David S. Miller <[email protected]>
cbmeeks · Sep 13, 2014 · 20adfa1 · 20adfa1
1 parent 9a72c2d
commit 20adfa1
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Showing 2 changed files with 13 additions and 4 deletions.
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
@@ -309,6 +309,9 @@ struct br_input_skb_cb {
 	int igmp;
 	int mrouters_only;
 #endif
+#ifdef CONFIG_BRIDGE_VLAN_FILTERING
+	bool vlan_filtered;
+#endif
 };
 
 #define BR_INPUT_SKB_CB(__skb)	((struct br_input_skb_cb *)(__skb)->cb)

diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
@@ -125,7 +125,8 @@ struct sk_buff *br_handle_vlan(struct net_bridge *br,
 {
 	u16 vid;
 
-	if (!br->vlan_enabled)
+	/* If this packet was not filtered at input, let it pass */
+	if (!BR_INPUT_SKB_CB(skb)->vlan_filtered)
 		goto out;
 
 	/* Vlan filter table must be configured at this point.  The
@@ -164,15 +165,18 @@ bool br_allowed_ingress(struct net_bridge *br, struct net_port_vlans *v,
 	/* If VLAN filtering is disabled on the bridge, all packets are
 	 * permitted.
 	 */
-	if (!br->vlan_enabled)
+	if (!br->vlan_enabled) {
+		BR_INPUT_SKB_CB(skb)->vlan_filtered = false;
 		return true;
+	}
 
 	/* If there are no vlan in the permitted list, all packets are
 	 * rejected.
 	 */
 	if (!v)
 		goto drop;
 
+	BR_INPUT_SKB_CB(skb)->vlan_filtered = true;
 	proto = br->vlan_proto;
 
 	/* If vlan tx offload is disabled on bridge device and frame was
@@ -251,7 +255,8 @@ bool br_allowed_egress(struct net_bridge *br,
 {
 	u16 vid;
 
-	if (!br->vlan_enabled)
+	/* If this packet was not filtered at input, let it pass */
+	if (!BR_INPUT_SKB_CB(skb)->vlan_filtered)
 		return true;
 
 	if (!v)
@@ -270,7 +275,8 @@ bool br_should_learn(struct net_bridge_port *p, struct sk_buff *skb, u16 *vid)
 	struct net_bridge *br = p->br;
 	struct net_port_vlans *v;
 
-	if (!br->vlan_enabled)
+	/* If filtering was disabled at input, let it pass. */
+	if (!BR_INPUT_SKB_CB(skb)->vlan_filtered)
 		return true;
 
 	v = rcu_dereference(p->vlan_info);