Re: [PATCH net] net: bridge: Do not offload IGMP/MLD messages
From: Tobias Waldekranz <tobias@waldekranz.com>
Date: 2025-07-02 08:41:50
Also in:
bridge, lkml
On tis, jul 01, 2025 at 15:36, Joseph Huang [off-list ref] wrote:
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.
Hi Joseph,
Do I understand the situation correctly that this is the case where the
local host is sending out reports in response to a remote querier?
mcast-listener-process (IP_ADD_MEMBERSHIP)
\
br0
/ \
swp1 swp2
| |
QUERIER SOME-OTHER-HOST
So 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?
quoted hunk ↗ jump to hunk
Fixes: 472111920f1c ("net: bridge: switchdev: allow the TX data plane forwarding to be offloaded") Signed-off-by: Joseph Huang <redacted> --- net/bridge/br_switchdev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c index 95d7355a0407..757c34bf5931 100644 --- a/net/bridge/br_switchdev.c +++ b/net/bridge/br_switchdev.c@@ -18,7 +18,8 @@ static bool nbp_switchdev_can_offload_tx_fwd(const struct net_bridge_port *p, return false; return (p->flags & BR_TX_FWD_OFFLOAD) && - (p->hwdom != BR_INPUT_SKB_CB(skb)->src_hwdom); + (p->hwdom != BR_INPUT_SKB_CB(skb)->src_hwdom) && + !br_multicast_igmp_type(skb); } bool br_switchdev_frame_uses_tx_fwd_offload(struct sk_buff *skb)-- 2.49.0