[net 1/1] tipc: accept PACKET_MULTICAST packets

[net 1/1] tipc: accept PACKET_MULTICAST packets

[Jon Maloy]

On L2 bearers, the TIPC broadcast function is sending out packets using
the corresponding L2 broadcast address. At reception, we filter such
packets under the assumption that they will also be delivered as
broadcast packets.

This assumption doesn't always hold true. Under high load, we have seen
that a switch may convert the destination address and deliver the packet
as a PACKET_MULTICAST, something leading to inadvertently dropped
packets and a stale and reset broadcast link.

We fix this by extending the reception filtering to accept packets of
type PACKET_MULTICAST.

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
---
 net/tipc/bearer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index d174ee3..767e053 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -596,7 +596,7 @@ static int tipc_l2_rcv_msg(struct sk_buff *skb, struct net_device *dev,
 	rcu_read_lock();
 	b = rcu_dereference_rtnl(dev->tipc_ptr);
 	if (likely(b && test_bit(0, &b->up) &&
-		   (skb->pkt_type <= PACKET_BROADCAST))) {
+		   (skb->pkt_type <= PACKET_MULTICAST))) {
 		skb->next = NULL;
 		tipc_rcv(dev_net(dev), skb, b);
 		rcu_read_unlock();
-- 
2.1.4

Re: [net 1/1] tipc: accept PACKET_MULTICAST packets

[David Miller]

From: Jon Maloy <jon.maloy@ericsson.com>
Date: Mon, 14 Aug 2017 17:55:56 +0200

> On L2 bearers, the TIPC broadcast function is sending out packets using
> the corresponding L2 broadcast address. At reception, we filter such
> packets under the assumption that they will also be delivered as
> broadcast packets.
> 
> This assumption doesn't always hold true. Under high load, we have seen
> that a switch may convert the destination address and deliver the packet
> as a PACKET_MULTICAST, something leading to inadvertently dropped
> packets and a stale and reset broadcast link.
> 
> We fix this by extending the reception filtering to accept packets of
> type PACKET_MULTICAST.
> 
> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>

Applied, thanks Jon.