From: Andrew Lunn andrew@lunn.ch
[ Upstream commit fbb3abdf2223cd0dfc07de85fe5a43ba7f435bdf ]
It is possible to stack bridges on top of each other. Consider the following which makes use of an Ethernet switch:
br1 / \ / \ / \ br0.11 wlan0 | br0 / | \ p1 p2 p3
br0 is offloaded to the switch. Above br0 is a vlan interface, for vlan 11. This vlan interface is then a slave of br1. br1 also has a wireless interface as a slave. This setup trunks wireless lan traffic over the copper network inside a VLAN.
A frame received on p1 which is passed up to the bridge has the skb->offload_fwd_mark flag set to true, indicating that the switch has dealt with forwarding the frame out ports p2 and p3 as needed. This flag instructs the software bridge it does not need to pass the frame back down again. However, the flag is not getting reset when the frame is passed upwards. As a result br1 sees the flag, wrongly interprets it, and fails to forward the frame to wlan0.
When passing a frame upwards, clear the flag. This is the Rx equivalent of br_switchdev_frame_unmark() in br_dev_xmit().
Fixes: f1c2eddf4cb6 ("bridge: switchdev: Use an helper to clear forward mark") Signed-off-by: Andrew Lunn andrew@lunn.ch Reviewed-by: Ido Schimmel idosch@nvidia.com Tested-by: Ido Schimmel idosch@nvidia.com Acked-by: Nikolay Aleksandrov razor@blackwall.org Link: https://lore.kernel.org/r/20220518005840.771575-1-andrew@lunn.ch Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/bridge/br_input.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c index 2532c1a19645..14c2fdc268ea 100644 --- a/net/bridge/br_input.c +++ b/net/bridge/br_input.c @@ -47,6 +47,13 @@ static int br_pass_frame_up(struct sk_buff *skb) u64_stats_update_end(&brstats->syncp);
vg = br_vlan_group_rcu(br); + + /* Reset the offload_fwd_mark because there could be a stacked + * bridge above, and it should not think this bridge it doing + * that bridge's work forwarding out its ports. + */ + br_switchdev_frame_unmark(skb); + /* Bridge is just like any other port. Make sure the * packet is allowed except in promisc modue when someone * may be running packet capture.