Subject: Re: [PATCH] bridge: pass correct vlan id to multicast code

From: Vlad Yasevich <[email-masked]>
Date: Tue, 29 Oct 2013 08:45:45 -0400

On 10/28/2013 10:36 PM, Amos Kong wrote:
> On Mon, Oct 28, 2013 at 03:45:07PM -0400, Vlad Yasevich wrote:
>> Currently multicast code attempts to extrace the vlan id from
>> the skb even when vlan filtering is disabled.  This can lead
>> to mdb entries being created with the wrong vlan id.
>> Pass the already extracted vlan id to the multicast
>> filtering code to make the correct id is used in
>> creation as well as lookup.
>
> Hi Vlad,
>
> Can we just update br_vlan_get_tag() to set vid to 0 if dev->vlan is
> disabled? I guess it would effect br_handle_local_finish().

I have another patch that refactors the br_vlan_get_tag() and that would 
address this issue.  I am testing it now.

I am hoping to simplify the patch a bit though since I am not
crazy about the function signature that br_vlan_get_tag() gets.

-vlad

>
>> Signed-off-by: Vlad Yasevich <[email-masked]>
>> ---
>>   net/bridge/br_device.c    |  2 +-
>>   net/bridge/br_input.c     |  2 +-
>>   net/bridge/br_multicast.c | 44 +++++++++++++++++++-------------------------
>>   net/bridge/br_private.h   |  6 ++++--
>>   4 files changed, 25 insertions(+), 29 deletions(-)
>
> ...
>
>> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
>> index 8b0b610..686284f 100644
>> --- a/net/bridge/br_multicast.c
>> +++ b/net/bridge/br_multicast.c
>> @@ -947,7 +947,8 @@ void br_multicast_disable_port(struct net_bridge_port *port)
>>
>>   static int br_ip4_multicast_igmp3_report(struct net_bridge *br,
>>   					 struct net_bridge_port *port,
>> -					 struct sk_buff *skb)
>> +					 struct sk_buff *skb,
>> +					 u16 vid)
>>   {
>>   	struct igmpv3_report *ih;
>>   	struct igmpv3_grec *grec;
>> @@ -957,12 +958,10 @@ static int br_ip4_multicast_igmp3_report(struct net_bridge *br,
>>   	int type;
>>   	int err = 0;
>>   	__be32 group;
>> -	u16 vid = 0;
>>
>>   	if (!pskb_may_pull(skb, sizeof(*ih)))
>>   		return -EINVAL;
>>
>> -	br_vlan_get_tag(skb, &vid);
>
> After applied the patch, we always use vid in br_dev_xmit()->br_allowed_ingress(),
> is it possible that the vlan of bridge is re-enabled when other
> changed functions are called?
>
> We can just add a enabled checking before this kind of br_vlan_get_tag()?
>
> if (!br->vlan_enabled)
>      br_vlan_get_tag(skb2, &vid);
>
>
>>   	ih = igmpv3_report_hdr(skb);
>>   	num = ntohs(ih->ngrec);
>>   	len = sizeof(*ih);
>
> ...
>