Do not offload IGMP/MLD messages as it could lead to IGMP/MLD Reports
being unintentionally flooded to Hosts. Instead, let the bridge decide
where to send these IGMP/MLD messages.
Consider the case where the local host is sending out reports in response
to a remote querier like the following:
mcast-listener-process (IP_ADD_MEMBERSHIP)
\
br0
/ \
swp1 swp2
| |
QUERIER SOME-OTHER-HOST
In the above setup, br0 will want to br_forward() reports for
mcast-listener-process's group(s) via swp1 to QUERIER; but since the
source hwdom is 0, the report is eligible for tx offloading, and is
flooded by hardware to both swp1 and swp2, reaching SOME-OTHER-HOST as
well. (Example and illustration provided by Tobias.)
Fixes: 472111920f1c ("net: bridge: switchdev: allow the TX data plane
forwarding to be offloaded")
Signed-off-by: Joseph Huang <[email protected]>
---
v1:
https://lore.kernel.org/netdev/[email protected]/
v2:
https://lore.kernel.org/netdev/[email protected]/
Updated commit message.
v3: Return early if it's an IGMP/MLD packet.
---
net/bridge/br_switchdev.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
index 95d7355a0407..9a910cf0256e 100644
--- a/net/bridge/br_switchdev.c
+++ b/net/bridge/br_switchdev.c
@@ -17,6 +17,9 @@ static bool nbp_switchdev_can_offload_tx_fwd(const struct
net_bridge_port *p,
if (!static_branch_unlikely(&br_switchdev_tx_fwd_offload))
return false;
+ if (br_multicast_igmp_type(skb))
+ return false;
+
return (p->flags & BR_TX_FWD_OFFLOAD) &&
(p->hwdom != BR_INPUT_SKB_CB(skb)->src_hwdom);
}
--
2.50.1
