From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sabrina Dubroca Subject: Re: [PATCH net-next] Revert "net/ipv6: add sysctl option accept_ra_min_hop_limit" Date: Thu, 10 Sep 2015 11:40:37 +0200 Message-ID: <20150910094037.GB22575@bistromath.redhat.com> References: <20150902094301.GA6434@via.ecp.fr> <20150902.161110.223512323094619164.davem@davemloft.net> <20150909101054.GA6753@bistromath.redhat.com> <55F11AAD.3030209@miraclelinux.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: David Miller , Florian Westphal , netdev@vger.kernel.org, liuhangbin@gmail.com To: YOSHIFUJI Hideaki Return-path: Received: from mx1.redhat.com ([209.132.183.28]:60448 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753088AbbIJJkk (ORCPT ); Thu, 10 Sep 2015 05:40:40 -0400 Content-Disposition: inline In-Reply-To: <55F11AAD.3030209@miraclelinux.com> Sender: netdev-owner@vger.kernel.org List-ID: 2015-09-10, 14:52:45 +0900, YOSHIFUJI Hideaki wrote: > Sabrina Dubroca wrote: > > 2015-09-02, 16:11:10 -0700, David Miller wrote: > >> The only thing I would entertain is potentially an adjustment of the > >> default, working in concert with the TAHI folks to make sure their > >> tests still pass with any new default. > > > > Would you agree with a default of 64, as Florian suggested? > > 1 was chosen to restore our behavior before introduction of current > hoplimit check. I am not in favor of changing that value. But our old behavior had a security issue, which is why the >= current check was introduced. > Plus, 64 is too restrictive and 32 would be enough for global > internet, IMHO. I guess I could live with that, if 32 is indeed enough for everybody. > > Can we still modify the behavior of this sysctl? It's already been in > > Linus's tree for a while, but if we can, I would rather restrict the > > values we let the user write to accept_ra_min_hop_limit, as anything > > outside [0..255] does not really make sense. > > [1..256], maybe, but it is not harmful to set outside the range. > 0 is always ignored. If it is set to 256 or more, the option is > completely ignored. Not harmful, but maybe slightly misleading, and requires the "< 256" check when processing a RA. > > Allowing an RA to update the hop limit if > > > > current hop limit < RA.hop_limit < accept_ra_min_hop_limit > > > > might also be desirable, but I'm not so sure about this case. > > > > > > It might be... byt I don't think it is a good idea since it becomes > more complex. A bit more complex, yes. But I don't think this should hold us back if it results in better behavior. Thanks, -- Sabrina