netdev - [PATCH net-next v2] net: bridge: locally receive all multicast packets if IFF

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Message-ID:
 <TYCPR01MB84378490F19C7BE975037B1698B12@TYCPR01MB8437.jpnprd01.prod.outlook.com>
Date: Sat, 12 Apr 2025 21:16:13 +0800
From: Shengyu Qu <wiagn233@...look.com>
To: razor@...ckwall.org,
	idosch@...dia.com,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	horms@...nel.org,
	bridge@...ts.linux.dev,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Shengyu Qu <wiagn233@...look.com>,
	Felix Fietkau <nbd@....name>
Subject: [PATCH net-next v2] net: bridge: locally receive all multicast packets if IFF_ALLMULTI is set

If multicast snooping is enabled, multicast packets may not always end up
on the local bridge interface, if the host is not a member of the multicast
group. Similar to how IFF_PROMISC allows all packets to be received
locally, let IFF_ALLMULTI allow all multicast packets to be received.

Signed-off-by: Felix Fietkau <nbd@....name>
Signed-off-by: Shengyu Qu <wiagn233@...look.com>
---
Since Felix didn't send v2 for this patch, I decided to do it by myself.

Changes since v1:
 - Move to net-next
 - Changed code according to Nikolay's advice
---
 net/bridge/br_input.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 232133a0fd21..aefcc3614373 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -189,7 +189,8 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 		    br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
 			if ((mdst && mdst->host_joined) ||
-			    br_multicast_is_router(brmctx, skb)) {
+			    br_multicast_is_router(brmctx, skb) ||
+				(br->dev->flags & IFF_ALLMULTI)) {
 				local_rcv = true;
 				DEV_STATS_INC(br->dev, multicast);
 			}
-- 
2.43.0