Commit a496d2f0 authored by Shengyu Qu's avatar Shengyu Qu Committed by Jakub Kicinski
Browse files

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.

OpenWrt uses a user space daemon for DHCPv6/RA/NDP handling, and in relay
mode it sets the ALLMULTI flag in order to receive all relevant queries on
the network.

This works for normal network interfaces and non-snooping bridges, but not
snooping bridges (unless multicast routing is enabled).

Reported-by: default avatarFelix Fietkau <nbd@nbd.name>
Closes: https://github.com/openwrt/openwrt/issues/15857#issuecomment-2662851243


Signed-off-by: default avatarShengyu Qu <wiagn233@outlook.com>
Reviewed-by: default avatarIdo Schimmel <idosch@nvidia.com>
Acked-by: default avatarNikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/OSZPR01MB8434308370ACAFA90A22980798B32@OSZPR01MB8434.jpnprd01.prod.outlook.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 1310f44d

net/bridge/br_input.c

+2 −1
Original line number Diff line number Diff line
@@ -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);

			}