[PATCH RFC net-next 02/10] net: bridge: Always multicast_flood Reports

[Joseph Huang]

Modify the forwarding path so that IGMPv1/v2/MLDv1 Reports are always
flooded by br_multicast_flood(), regardless of the check done
by br_multicast_querier_exists().

This patch fixes the problems where shortly after a system boots up,
the first couple of Reports are not handled properly in that:

1) The Report from the Host is being flooded (via br_flood) to all
   bridge ports, and
2) If the mrouter port's multicast flooding is disabled, the Reports
   received from other hosts will not be forwarded to the Querier.

Fixes: b00589af3b04 ("bridge: disable snooping if there is no querier")

Signed-off-by: Joseph Huang <Joseph.Huang@xxxxxxxxxx>
---
 net/bridge/br_device.c    | 5 +++--
 net/bridge/br_input.c     | 5 +++--
 net/bridge/br_multicast.c | 5 +++++
 net/bridge/br_private.h   | 3 +++
 4 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index c366ccc8b3db..5c09b9dd61dc 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -93,8 +93,9 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 		}
 
 		mdst = br_mdb_entry_skb_get(brmctx, skb, vid);
-		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
-		    br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst))
+		if (((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
+		     br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) ||
+		    BR_INPUT_SKB_CB_FORCE_MC_FLOOD(skb))
 			br_multicast_flood(mdst, skb, brmctx, false, true);
 		else
 			br_flood(br, skb, BR_PKT_MULTICAST, false, true, vid);
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index f21097e73482..8e614ab20966 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -176,8 +176,9 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 	switch (pkt_type) {
 	case BR_PKT_MULTICAST:
 		mdst = br_mdb_entry_skb_get(brmctx, skb, vid);
-		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
-		    br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
+		if (((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
+		     br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) ||
+		    BR_INPUT_SKB_CB_FORCE_MC_FLOOD(skb)) {
 			if ((mdst && mdst->host_joined) ||
 			    br_multicast_is_router(brmctx, skb)) {
 				local_rcv = true;
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 42d900549227..8531f0e03f41 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -3844,6 +3844,7 @@ static int br_multicast_ipv4_rcv(struct net_bridge_mcast *brmctx,
 	case IGMP_HOST_MEMBERSHIP_REPORT:
 	case IGMPV2_HOST_MEMBERSHIP_REPORT:
 		BR_INPUT_SKB_CB(skb)->mrouters_only = 1;
+		BR_INPUT_SKB_CB(skb)->force_mc_flood = 1;
 		err = br_ip4_multicast_add_group(brmctx, pmctx, ih->group, vid,
 						 src, true);
 		break;
@@ -3855,6 +3856,7 @@ static int br_multicast_ipv4_rcv(struct net_bridge_mcast *brmctx,
 		br_ip4_multicast_query(brmctx, pmctx, skb, vid);
 		break;
 	case IGMP_HOST_LEAVE_MESSAGE:
+		BR_INPUT_SKB_CB(skb)->force_mc_flood = 1;
 		br_ip4_multicast_leave_group(brmctx, pmctx, ih->group, vid, src);
 		break;
 	}
@@ -3910,6 +3912,7 @@ static int br_multicast_ipv6_rcv(struct net_bridge_mcast *brmctx,
 	case ICMPV6_MGM_REPORT:
 		src = eth_hdr(skb)->h_source;
 		BR_INPUT_SKB_CB(skb)->mrouters_only = 1;
+		BR_INPUT_SKB_CB(skb)->force_mc_flood = 1;
 		err = br_ip6_multicast_add_group(brmctx, pmctx, &mld->mld_mca,
 						 vid, src, true);
 		break;
@@ -3922,6 +3925,7 @@ static int br_multicast_ipv6_rcv(struct net_bridge_mcast *brmctx,
 		break;
 	case ICMPV6_MGM_REDUCTION:
 		src = eth_hdr(skb)->h_source;
+		BR_INPUT_SKB_CB(skb)->force_mc_flood = 1;
 		br_ip6_multicast_leave_group(brmctx, pmctx, &mld->mld_mca, vid,
 					     src);
 		break;
@@ -3944,6 +3948,7 @@ int br_multicast_rcv(struct net_bridge_mcast **brmctx,
 	BR_INPUT_SKB_CB(skb)->igmp = 0;
 	BR_INPUT_SKB_CB(skb)->mrouters_only = 0;
 	BR_INPUT_SKB_CB(skb)->force_flood = 0;
+	BR_INPUT_SKB_CB(skb)->force_mc_flood = 0;
 
 	if (!br_opt_get((*brmctx)->br, BROPT_MULTICAST_ENABLED))
 		return 0;
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index c28e0cd0855c..d72a632a1ad2 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -587,6 +587,7 @@ struct br_input_skb_cb {
 	u8 igmp;
 	u8 mrouters_only:1;
 	u8 force_flood:1;
+	u8 force_mc_flood:1;
 #endif
 	u8 proxyarp_replied:1;
 	u8 src_port_isolated:1;
@@ -622,9 +623,11 @@ 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)
+# define BR_INPUT_SKB_CB_FORCE_MC_FLOOD(__skb)	(BR_INPUT_SKB_CB(__skb)->force_mc_flood)
 #else
 # define BR_INPUT_SKB_CB_MROUTERS_ONLY(__skb)	(0)
 # define BR_INPUT_SKB_CB_FORCE_FLOOD(__skb)	(0)
+# define BR_INPUT_SKB_CB_FORCE_MC_FLOOD(__skb)	(0)
 #endif
 
 #define br_printk(level, br, format, args...)	\
-- 
2.17.1