netdev - [PATCH 5/6] bridge: Flood Queries even when mcast

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Date:   Tue, 4 May 2021 14:22:58 -0400
From:   Joseph Huang <Joseph.Huang@...min.com>
To:     Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        <bridge@...ts.linux-foundation.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     Joseph Huang <Joseph.Huang@...min.com>
Subject: [PATCH 5/6] bridge: Flood Queries even when mcast_flood is disabled

Modify the forwarding path so that received Queries are always flooded
even when mcast_flood is disabled on a bridge port.

In current implementation, when mcast_flood is disabled on a bridge
port, Queries received from other Querier will not be forwarded out of
that bridge port. This unfortunately broke multicast snooping.

Signed-off-by: Joseph Huang <Joseph.Huang@...min.com>
---
 net/bridge/br_forward.c   | 3 ++-
 net/bridge/br_multicast.c | 3 +++
 net/bridge/br_private.h   | 3 +++
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index 6e9b049ae521..2fb9b4a78881 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -203,7 +203,8 @@ void br_flood(struct net_bridge *br, struct sk_buff *skb,
 				continue;
 			break;
 		case BR_PKT_MULTICAST:
-			if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
+			if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev &&
+			    !BR_INPUT_SKB_CB_FORCE_FLOOD(skb))
 				continue;
 			break;
 		case BR_PKT_BROADCAST:
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 719ded3204a0..b7d9c491abe0 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -3238,6 +3238,7 @@ static int br_multicast_ipv4_rcv(struct net_bridge *br,
 		err = br_ip4_multicast_igmp3_report(br, port, skb, vid);
 		break;
 	case IGMP_HOST_MEMBERSHIP_QUERY:
+		BR_INPUT_SKB_CB(skb)->force_flood = 1;
 		br_ip4_multicast_query(br, port, skb, vid);
 		break;
 	case IGMP_HOST_LEAVE_MESSAGE:
@@ -3300,6 +3301,7 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br,
 		err = br_ip6_multicast_mld2_report(br, port, skb, vid);
 		break;
 	case ICMPV6_MGM_QUERY:
+		BR_INPUT_SKB_CB(skb)->force_flood = 1;
 		err = br_ip6_multicast_query(br, port, skb, vid);
 		break;
 	case ICMPV6_MGM_REDUCTION:
@@ -3322,6 +3324,7 @@ int br_multicast_rcv(struct net_bridge *br, struct net_bridge_port *port,
 
 	BR_INPUT_SKB_CB(skb)->igmp = 0;
 	BR_INPUT_SKB_CB(skb)->mrouters_only = 0;
+	BR_INPUT_SKB_CB(skb)->force_flood = 0;
 
 	if (!br_opt_get(br, BROPT_MULTICAST_ENABLED))
 		return 0;
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 9aa51508ba83..59af599d48eb 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -491,6 +491,7 @@ struct br_input_skb_cb {
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 	u8 igmp;
 	u8 mrouters_only:1;
+	u8 force_flood:1;
 #endif
 	u8 proxyarp_replied:1;
 	u8 src_port_isolated:1;
@@ -510,8 +511,10 @@ struct br_input_skb_cb {
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 # define BR_INPUT_SKB_CB_MROUTERS_ONLY(__skb)	(BR_INPUT_SKB_CB(__skb)->mrouters_only)
+# define BR_INPUT_SKB_CB_FORCE_FLOOD(__skb)		(BR_INPUT_SKB_CB(__skb)->force_flood)
 #else
 # define BR_INPUT_SKB_CB_MROUTERS_ONLY(__skb)	(0)
+# define BR_INPUT_SKB_CB_FORCE_FLOOD(__skb)		(0)
 #endif
 
 #define br_printk(level, br, format, args...)	\
-- 
2.17.1