From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [RFC net] bridge: clean the nf_bridge status when forwarding the skb Date: Mon, 14 Oct 2013 15:27:56 -0700 Message-ID: <20131014152756.7b83dcc0@nehalam.linuxnetplumber.net> References: <1380226790-513-1-git-send-email-antonio@meshcoding.com> <20130926141021.3cde0f0f@nehalam.linuxnetplumber.net> <20130926211648.GB1228@open-mesh.com> <20130926143248.2799b4ea@nehalam.linuxnetplumber.net> <20130926220143.GC1228@open-mesh.com> <20131014222010.GB3873@neomailbox.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , "bridge@lists.linux-foundation.org" , "netdev@vger.kernel.org" To: Antonio Quartulli Return-path: Received: from mail-pb0-f42.google.com ([209.85.160.42]:50907 "EHLO mail-pb0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757333Ab3JNW17 (ORCPT ); Mon, 14 Oct 2013 18:27:59 -0400 Received: by mail-pb0-f42.google.com with SMTP id un15so7934141pbc.29 for ; Mon, 14 Oct 2013 15:27:59 -0700 (PDT) In-Reply-To: <20131014222010.GB3873@neomailbox.net> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 15 Oct 2013 00:20:10 +0200 Antonio Quartulli 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.