From: Stephen Hemminger <stephen@networkplumber•org>
To: Antonio Quartulli <antonio@meshcoding•com>
Cc: "David S. Miller" <davem@davemloft•net>,
"bridge@lists•linux-foundation.org"
<bridge@lists•linux-foundation.org>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>
Subject: Re: [RFC net] bridge: clean the nf_bridge status when forwarding the skb
Date: Mon, 14 Oct 2013 15:27:56 -0700 [thread overview]
Message-ID: <20131014152756.7b83dcc0@nehalam.linuxnetplumber.net> (raw)
In-Reply-To: <20131014222010.GB3873@neomailbox.net>
On Tue, 15 Oct 2013 00:20:10 +0200
Antonio Quartulli <antonio@meshcoding•com> wrote:
> On Fri, Sep 27, 2013 at 12:01:43AM +0200, Antonio Quartulli wrote:
> > On Thu, Sep 26, 2013 at 02:32:48PM -0700, Stephen Hemminger wrote:
> > > > > > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > > > > > index 4b81b14..65864bc 100644
> > > > > > --- a/net/bridge/br_forward.c
> > > > > > +++ b/net/bridge/br_forward.c
> > > > > > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> > > > > > } else {
> > > > > > skb_push(skb, ETH_HLEN);
> > > > > > br_drop_fake_rtable(skb);
> > > > > > +
> > > > > > + /* clean the NF bridge data */
> > > > > > + nf_bridge_put(skb->nf_bridge);
> > > > > > + skb->nf_bridge = NULL;
> > > > > > +
> > > > > > dev_queue_xmit(skb);
> > > > > > }
> > > > > >
> > > >
> > > > Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.
> > > >
> > > > >
> > > > > I think the header will also be garbage if bridge on bridge with netfilter is used.
> > > > > See nf_bridge_save_header.
> > > >
> > > > What header are you referring to? nf_bridge_save_header() saves the header in
> > > > skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
> > > > ->use reached 0).
> > > >
> > > >
> > >
> > > If bridge is stacked the original ether header will get overwritten by the second
> > > call to save_header.
> >
> > Sorry, but I am not getting what you mean (I am new to the code and it is late here..):
> > save_header() will store the Ethernet header in nf_bridge->data for
> > later recover (if needed).
> >
> > By freeing nf_bridge I also destroy this header copy.
> >
> > When the skb enters the second bridge, save_header() will save again the header
> > in nf_bridge->data. But I don't see how this can create a problem.
> >
> > The problem I had before this patch comes from the fact that
> > nf_bridge_copy_header() is invoked in the second bridge with the nf_bridge state
> > of the first. This was overwriting my the packet Ethernet header with what the
> > first invocation of save_header() stored in nf_bridge->data.
> >
> > But by unsetting nf_bridge I think I am preventing this from happening again.
> > no?
>
> Hello Stephen,
>
> do you have other comments about this patch? I know it is rather difficult that
> a generic user hits this issue, but I'd like to see it fixed because other
> people using batman-adv may incur in this problem.
>
> Cheers,
>
>
The patch content is fine, but it needs necessary ifdef's.
I would also prefer to have the clean done as a function that can be stubbed out
like the other bridge netfilter stuff.
next prev parent reply other threads:[~2013-10-14 22:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-26 20:19 [RFC net] bridge: clean the nf_bridge status when forwarding the skb Antonio Quartulli
2013-09-26 21:08 ` Stephen Hemminger
2013-09-26 21:10 ` Stephen Hemminger
2013-09-26 21:16 ` Antonio Quartulli
2013-09-26 21:32 ` Stephen Hemminger
2013-09-26 22:01 ` Antonio Quartulli
2013-10-14 22:20 ` Antonio Quartulli
2013-10-14 22:27 ` Stephen Hemminger [this message]
2013-10-14 22:35 ` Antonio Quartulli
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