From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: Linux kernel patch: elide fib_validate_source() completely when possible - bad side effect? Date: Thu, 23 Jan 2014 15:20:58 +0100 Message-ID: <20140123142058.GK7269@order.stressinduktion.org> References: <52DCF1440200005D000477FD@gwia2.atlnz.lc> <20140123020224.GG7269@order.stressinduktion.org> <20140122.185305.1125981867482223830.davem@davemloft.net> <20140123030329.GI7269@order.stressinduktion.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: David Miller , gregory.hoggarth@alliedtelesis.co.nz, netdev@vger.kernel.org To: Julian Anastasov Return-path: Received: from order.stressinduktion.org ([87.106.68.36]:60479 "EHLO order.stressinduktion.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932095AbaAWOU7 (ORCPT ); Thu, 23 Jan 2014 09:20:59 -0500 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Hi Julian, On Thu, Jan 23, 2014 at 11:47:33AM +0200, Julian Anastasov wrote: > On Thu, 23 Jan 2014, Hannes Frederic Sowa wrote: > > > E.g. we register all local registered broadcast addresses in a structure > > like inet_addr_lst so we only need to check if the packet would leave > > this host with a broadcast hardware address. If the packet is forwarded > > the router must do the same check as only it knows the local broadcast > > addresses. I hope this is correct. ;) > > Now when we can override the local table with ip > rules or to prepend route in local table, we can not be > sure that the broadcast routes are returned in all cases, > users can add unicast routes for such addresses. > > I don't remember for useful case where one may need to > override broadcast routes but adding such exceptions looks > risky. The check I envisioned would only actually block the ifa_broadcast of only the incoming interface as source address. So we wouldn't depend on the view of the routing tables at all. But I have no strong opinion on that. Greetings, Hannes