netdev - Re: [PATCH net] bridge: clean the nf_bridge status when forwarding the skb

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Date:	Fri, 18 Oct 2013 17:41:23 +0200
From:	Antonio Quartulli <antonio@...hcoding.com>
To:	Vlad Yasevich <vyasevic@...hat.com>
Cc:	Pablo Neira Ayuso <pablo@...filter.org>,
	Antonio Quartulli <antonio@...n-mesh.com>,
	"David S. Miller" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Stephen Hemminger <stephen@...workplumber.org>
Subject: Re: [PATCH net] bridge: clean the nf_bridge status when forwarding
 the skb

On Fri, Oct 18, 2013 at 11:33:06AM -0400, Vlad Yasevich wrote:
> On 10/18/2013 10:46 AM, Antonio Quartulli wrote:
> > On Fri, Oct 18, 2013 at 10:32:09AM -0400, Vlad Yasevich wrote:
> >> On 10/18/2013 07:35 AM, Antonio Quartulli wrote:
> >>> On Fri, Oct 18, 2013 at 01:10:41PM +0200, Pablo Neira Ayuso wrote:
> >>>> On Thu, Oct 17, 2013 at 01:37:35PM +0200, Antonio Quartulli wrote:
> >>>>> On Thu, Oct 17, 2013 at 04:28:57AM -0700, Pablo Neira Ayuso wrote:
> >
> > [...]
> >
> >>>
> >>> The problem I was having was due to an skb entering br0 first and br1 later.
> >>> When reaching br1 skb->nf_bridge was != NULL because of the previous processing
> >>> in br0.
> >>>
> >>
> >> Doesn't br_nf_pre_routing already take care of this for you?  It will
> >> drop the ref on the current nf_bridge and allocate a new one.  Is that
> >> not sufficient?
> >
> > In my case that line is not reached because
> >
> >   700         if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
> >
> > is always true: the packet getting analysed is a batman-adv encapsulated packet,
> > which does not match any of the three above.
> >
> > Cheers,
> >
> 
> Looking at other encapsulators (PPP, iptunnel, VXLAN), they do
> nf_reset() on input.  Would that be appropriate for batman as well?

I thought that too.

But at this point, wouldn't it be better to do a reset here and remove the other
resets from any other encapsulation module?

Maybe this operation is supposed to not happen if no encapsulation is involved?
I thought that polishing the nf state when exiting the nf related path was a
clean and easy solution.

Moreover we avoid that any newly implemented tunneling module hit this problem again.


Cheers,

-- 
Antonio Quartulli

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