From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Masters Subject: Re: [PATCH for 2.6.33] conntrack: restrict runtime hashsize modifications Date: Thu, 04 Feb 2010 15:18:54 -0500 Message-ID: <1265314734.2861.521.camel@tonnant> References: <20100203203929.GA6168@x200> <4B6AF36A.3050402@trash.net> <4B6AF58A.202@trash.net> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Alexey Dobriyan , davem@davemloft.net, eric.dumazet@gmail.com, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org To: Patrick McHardy Return-path: Received: from dallas.jonmasters.org ([72.29.103.172]:49012 "EHLO dallas.jonmasters.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751633Ab0BDUTR (ORCPT ); Thu, 4 Feb 2010 15:19:17 -0500 In-Reply-To: <4B6AF58A.202@trash.net> Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Thu, 2010-02-04 at 17:27 +0100, Patrick McHardy wrote: > Patrick McHardy wrote: > > Alexey Dobriyan wrote: > >> Jon Masters correctly points out that conntrack hash sizes > >> (nf_conntrack_htable_size) are global (not per-netns) and > >> modifiable at runtime via /sys/module/nf_conntrack/hashsize . > >> > >> Steps to reproduce: > >> clone(CLONE_NEWNET) > >> [grow /sys/module/nf_conntrack/hashsize] > >> exit() > >> > >> At netns exit we are going to scan random memory for conntracks to be killed. > >> > >> Apparently there is a code which deals with hashtable resize for > >> init_net (and it was there befode netns conntrack code), so prohibit > >> hashsize modification if there is more than one netns exists. > >> > >> To change hashtable sizes, you need to reload module. > >> > >> Expectation hashtable size was simply glued to a variable with no code > >> to rehash expectations, so it was a bug to allow writing to it. > >> Make "expect_hashsize" readonly. > >> > >> This is temporarily until we figure out what to do. > > > > How about alternatively moving nf_conntrack_hsize into the > > per-namespace struct? It doesn't look more complicated or > > intrusive and would allow to still change the init_net > > hashsize. Also seems less hackish :) > > Just to avoid duplicate work, I'm currently trying that. Bah. I already worked a set of patches to do that as I mentioned, but you've probably done it by now - can clean up and post if not :) Jon.