Date: Thu, 17 Aug 2006 11:16:51 +0400 From: Yar Tikhiy <yar@comp.chem.msu.su> To: Brooks Davis <brooks@one-eyed-alien.net> Cc: drl@MyBSD.org.my, freebsd-stable@freebsd.org, Stefan Bethke <stb@lassitu.de>, Andrew Thompson <thompsa@freebsd.org> Subject: Re: Default route (IPv4) demolished by destroying clone (gif/gre) interface Message-ID: <20060817071651.GB94460@comp.chem.msu.su> In-Reply-To: <20060816205913.GA69877@lor.one-eyed-alien.net> References: <20060815040736.2f85f090.drl@MyBSD.org.my> <9405D801-3435-419A-9541-E1A9B2CF26D2@lassitu.de> <20060816081130.GB81271@comp.chem.msu.su> <FED9705F-B445-4495-B90F-A656AAA966EE@lassitu.de> <20060816145419.GB62485@lor.one-eyed-alien.net> <20060816155844.GA85503@comp.chem.msu.su> <20060816171524.GA63928@lor.one-eyed-alien.net> <20060816204927.GA73369@heff.fud.org.nz> <20060816205913.GA69877@lor.one-eyed-alien.net>
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On Wed, Aug 16, 2006 at 03:59:13PM -0500, Brooks Davis wrote:
> On Thu, Aug 17, 2006 at 08:49:27AM +1200, Andrew Thompson wrote:
> > On Wed, Aug 16, 2006 at 12:15:25PM -0500, Brooks Davis wrote:
> > > On Wed, Aug 16, 2006 at 07:58:44PM +0400, Yar Tikhiy wrote:
> > > > On Wed, Aug 16, 2006 at 09:54:19AM -0500, Brooks Davis wrote:
> > > > > On Wed, Aug 16, 2006 at 10:23:13AM +0200, Stefan Bethke wrote:
> > > > > >
> > > > > > Ouch. Don't ppp(8), OpenVPN etc. destroy the tun interface they're
> > > > > > using when they exit? Flushing all routes then would be rather
> > > > > > harmful. I'm glad I haven't updated to a newer -stable yet then :-)
> > > > >
> > > > > In general, no since tun interfaces can not be destroyed.
> > > >
> > > > Did you mean "in particular"? :-)
> > > >
> > > > The problem can be triggered by destroying any interface that can
> > > > be destroyed. Just imagine getting rid of a defunct gif tunnel on
> > > > a remote router, or removing an unused vlan, and totally losing
> > > > connectivity to the router due to its default route having been
> > > > flushed. The scenario still can be quite unpleasant. I'd rather
> > > > change the default for $removable_route_flush to NO and let the
> > > > kernel choose which routes should be flushed upon the physical
> > > > ejection or software destruction of an interface. Note that this
> > > > doesn't include static_routes_${ifn}, which are handled separately
> > > > by pccard_ether_stop().
> > >
> > > Agreed. That code shouldn't be on by default. I've disabled in it HEAD
> > > and will MFC in a few days. As another poster said, I'm not even sure
> > > it should exist as an option.
> >
> > Thanks for fixing this up, it certainly was odd to be flushing routes in
> > userland. I have one more bug report from the ifnet/devd change to look
> > at where renamed interfaces give some sort of an error.
>
> It is a rather weird bit of code. It deletes all IPv4 routes on exit.
> I suspect it's a hack left over from before interface removal really
> worked. I may just delete the code in HEAD after the MFC. I think we
> could also remove the arp flush or move it into "netif stop" and narrow
> it with the -i option.
The -i option may not work in that case because the interface has
ceased to exist by the time devd(8) gets the notification and runs
/etc/pccard_ether. It could be better just to remove the arp flush
completely. The kernel should take care of the arp entries by itself.
Thanks!
--
Yar
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