From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: Re: [PATCH nf-next 0/8] netfilter: untangle bridge and bridge netfilter Date: Mon, 9 Mar 2015 14:59:10 +0100 Message-ID: <20150309135910.GC1528@breakpoint.cc> References: <1425513160-496-1-git-send-email-fw@strlen.de> <20150309130253.GA6677@salvia> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Florian Westphal , netfilter-devel@vger.kernel.org, netdev@vger.kernel.org To: Pablo Neira Ayuso Return-path: Content-Disposition: inline In-Reply-To: <20150309130253.GA6677@salvia> Sender: netdev-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org Pablo Neira Ayuso wrote: > > nf_bridge is kmalloced blob with some extra information, including > > the bridge in and outports (mainly for iptables' physdev match). > > It also has various state bits so we know what manipulations > > have been performed by bridge netfilter on the skb (e.g. > > ppp header stripping). > > > > nf_bridge also provides scratch space where br_netfilter saves > > (and later restores) various things, e.g. ipv4 address for > > dnat detection, mac address to fix up ip fragmented skbs, etc. > > > > But in almost all cases we can avoid using ->data completely. > > I think one of the goals of this patchset is to prepare the removal of > that nf_bridge pointer from sk_buff which sounds as a good idea to me. > > Did you consider to implement this scratchpad area using a per-cpu > area? I mean, something similar to what we used to have in > ip_conntrack for events: I see that I misread part of what you wrote. We cannot use percpu data for nf_bridge_info; at least its not trivial to do (I tried). Main issues are: - nfqueue (we have to save/restore info) - local delivery (skb is enqueued in backlog) - skb is dropped (we need to reset scratch data) - DNAT mac hack (skb can be queued in qdisc). We _can_ use percpu data for passing the original mac header to the ip_fragment output function. But, as mentioned, there is a patch in netdev patchwork that adds extra output parameter for use with OVS so it seems cleaner to (re-) use common api in both OVS and br netfilter. > BTW, 6/8 I think needs some ifdef to make sure NF_CONNTRACK is in > placed. Right, thanks for catching this. > 7/8 needs NF_BRDIGE_MAX_MAC_HEADER_LENGTH which seems to have > a small typo in it, well these are dependent of 4/8 anyway. Sorry -- I'm dense -- what typo? :-)