Linux Ethernet Bridging - Jul 2014 - [Bridge] [PATCH net] bridge: Don't include NDA_VLAN for FDB entries with vid 0

An FDB entry with vlan_id 0 doesn't mean it is used in vlan 0, but used when
vlan_filtering is disabled.

There is inconsistency around NDA_VLAN whose payload is 0 - even if we add
an entry by RTM_NEWNEIGH without any NDA_VLAN, and even though adding an
entry with NDA_VLAN 0 is prohibited, we get an entry with NDA_VLAN 0 by
RTM_GETNEIGH.

Dumping an FDB entry with vlan_id 0 shouldn't include NDA_VLAN.

Signed-off-by: Toshiaki Makita <makita.toshiaki at lab.ntt.co.jp>
---
 net/bridge/br_fdb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index b524c36..02359e8 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -631,7 +631,7 @@ static int fdb_fill_info(struct sk_buff *skb, const struct
net_bridge *br,
 	if (nla_put(skb, NDA_CACHEINFO, sizeof(ci), &ci))
 		goto nla_put_failure;
 
-	if (nla_put(skb, NDA_VLAN, sizeof(u16), &fdb->vlan_id))
+	if (fdb->vlan_id && nla_put(skb, NDA_VLAN, sizeof(u16),
&fdb->vlan_id))
 		goto nla_put_failure;
 
 	return nlmsg_end(skb, nlh);
-- 
1.8.1.2

From: Toshiaki Makita <makita.toshiaki at lab.ntt.co.jp>
Date: Wed, 30 Jul 2014 13:31:51 +0900
> An FDB entry with vlan_id 0 doesn't mean it is used in vlan 0, but used
when
> vlan_filtering is disabled.
> 
> There is inconsistency around NDA_VLAN whose payload is 0 - even if we add
> an entry by RTM_NEWNEIGH without any NDA_VLAN, and even though adding an
> entry with NDA_VLAN 0 is prohibited, we get an entry with NDA_VLAN 0 by
> RTM_GETNEIGH.
> 
> Dumping an FDB entry with vlan_id 0 shouldn't include NDA_VLAN.
> 
> Signed-off-by: Toshiaki Makita <makita.toshiaki at lab.ntt.co.jp>
This is clearly the right thing to do, since upon FDB addition we reject
NDA_VLAN attributes with value zero.

Applied, thanks.