lkml.org 
[lkml]   [2012]   [Nov]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1/2] autofs4: allow autofs to work outside the initial PID namespace
From
Date
On Sat, 2012-11-24 at 14:35 -0800, Eric W. Biederman wrote:
> Miklos Szeredi <miklos@szeredi.hu> writes:
>
> > On Sat, Nov 24, 2012 at 1:07 PM, Eric W. Biederman
> > <ebiederm@xmission.com> wrote:
> >> Ian Kent <raven@themaw.net> writes:
> >>
> >>> On Sat, 2012-11-24 at 10:23 +0800, Ian Kent wrote:
> >>>> On Fri, 2012-11-23 at 15:30 +0100, Miklos Szeredi wrote:
> >
> >>>> AFAICS autofs mounts mounted with MS_PRIVATE in the initial namespace do
> >>>> propagate to the clone when it's created so I'm assuming subsequent
> >>>> mounts would also. If these mounts are busy in some way they can't be
> >>>> umounted in the clone unless "/" is marked private before attempting the
> >>>> umount.
>
> Subsequent mounts after the clone do not have a mechanism to propogate
> with MS_PRIVATE. As creating a new mount namespaces is essentially
> an instance of mount --bind. Those semantics are a little unintuitive
> I have to admit.
>
> >>> This may sound stupid but if there something like, say, MS_NOPROPAGATE
> >>> then the problem I see would pretty much just go away. No more need to
> >>> umount existing mounts and container instances would be isolated. But, I
> >>> guess, I'm not considering the possibility of cloned of processes as
> >>> well .... if that makes sense, ;)
> >>
> >> Something is very weird is going on. MS_PRIVATE should be the
> >> MS_NOPROPOGATE you are looking for. There is also MS_UNBINDABLE.
> >> which is a stronger form of MS_PRIVATE and probably worth play with.
> >>
> >
> > MS_UNBINDABLE says: skip this mount when copying a mount tree, such
> > as when the mount namespace is cloned.
> >
> > If you set MS_UNBINDABLE on autofs mounts then they will simply not
> > appear in a cloned namespace. Which sounds like a good idea, no?
>
> Good point. If the desire is for a mount to be managed by autofs
> setting MS_UNBINDABLE seems required.

Arrgh, I know that's something I should have looked into long ago.
The fact is that autofs mounts are directly related to a specific path
defined by automount maps that are associated with the daemon so bind
mounting them elsewhere makes no sense.

Is it necessary (or sensible) to use MS_PRIVATE with MS_UNBINDABLE?

>
> Eric
>




\
 
 \ /
  Last update: 2012-11-26 01:01    [W:0.067 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site