[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20231016073251.0f47d42b@kernel.org>
Date: Mon, 16 Oct 2023 07:32:51 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Daniel Gröber <dxld@...kboxed.org>, "David S. Miller"
<davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Paolo Abeni
<pabeni@...hat.com>, netdev@...r.kernel.org, Richard Weinberger
<richard@....at>, Serge Hallyn <serge.hallyn@...onical.com>, "Eric W.
Biederman" <ebiederm@...ssion.com>
Subject: Re: [BUG] rtnl_newlink: Rogue MOVE event delivered on netns change
On Sat, 14 Oct 2023 10:58:20 +0200 Greg Kroah-Hartman wrote:
> On Fri, Oct 13, 2023 at 03:43:02PM -0700, Jakub Kicinski wrote:
> > On Fri, 13 Oct 2023 15:36:05 -0700 Jakub Kicinski wrote:
> > > kobject_uevent(&dev->dev.kobj, KOBJ_REMOVE);
> > > dev_net_set(dev, net);
> > > kobject_uevent(&dev->dev.kobj, KOBJ_ADD);
> >
> > Greg, we seem to have a problem in networking with combined
> > netns move and name change.
> >
> > We have this code in __dev_change_net_namespace():
> >
> > kobject_uevent(&dev->dev.kobj, KOBJ_REMOVE);
> > dev_net_set(dev, net);
> > kobject_uevent(&dev->dev.kobj, KOBJ_ADD);
> >
> > err = device_rename(&dev->dev, dev->name);
> >
> > Is there any way we can only get the REMOVE (old name) and ADD
> > (new name) events, without the move? I.e. silence the rename?
> >
> > Daniel is reporting that with current code target netns sees an
> > add of an interface with the old (duplicated) name. And then a rename.
>
> But that's how this has always been, right? What problems is this
> causing?
Original report is up-thread:
https://lore.kernel.org/all/20231010121003.x3yi6fihecewjy4e@House.clients.dxld.at/
With a link to a GH issue for lxc:
https://github.com/lxc/incus/issues/146
> > Without a silent move best we can do is probably:
> >
> > kobject_uevent(&dev->dev.kobj, KOBJ_REMOVE);
> > dev_net_set(dev, net);
> > err = device_rename(&dev->dev, dev->name);
> > kobject_uevent(&dev->dev.kobj, KOBJ_ADD);
> >
> > which will give us:
> >
> > MOVE new-name
> > ADD new-name
> >
> > in target netns, which, hm.
>
> That wouldn't make much sense.
>
> What is the real problem here? What changed to cause a problem?
IIUC what happens is:
- systemd controls "real" eth0
- we move a "to be renamed" eth0 from a container into main ns
- we rename "to be renamed" eth0 to something else
- seeing the rename of eth0 system thinks it's the "real" one
that is being renamed, ergo there's no eth0 any more,
so it shuts down its "unit" for eth0
I don't think anything changed. Sounds more like someone finally tried
to use this in anger.
Powered by blists - more mailing lists