Re: [PATCH] cifs: handle termination of cifs oplockd kernel thread

[Christoph Hellwig <hch@infradead.org>]

On Sat, Apr 30, 2005 at 10:14:07AM +0200, Miklos Szeredi wrote:
> > Except that we don't have the concept of a mount owner at the VFS level
> > right now, because everyone is adding stupid suid wrapper hacks instead
> > of trying to fix the problems for real.
> 
> Having a mount owner is not a problem.  Having a good policy for
> accepting mounts is rather more so, according to some:
> 
>    http://marc.theaimsgroup.com/?l=linux-kernel&m=107705608603071&w=2
> 
> Just a little taste of what that policy would involve:
> 
>   - global limit on user mounts

I don't think we need that one.

>   - possibly per user limit on mounts

Makes sense as an ulimit, that way the sysadmin can easily disable the
user mount feature aswell.

>   - acceptable mountpoints (unlimited writablity is probably a good minimum)

Yupp.

>   - acceptable mount options (nosuid, nodev are obviously not)

noexecis a bit too much, so the above look good.

>   - filesystems "safe" to mount by users

what filesystem do you think is unsafe?

 - virtual filesystems exporting kernel data are obviously safe as
   they enforce permissions no matter who mounted them.  (actually we'd
   need to check for some odd mount options)

 - block-based filesystems should be safe as long as the mounter has
   access to the underlying block device

 - network/userspace filesystems should be fine aswell