Re: [PATCH] cgroups: devices: add Documentation/ file

[Serge E. Hallyn]

Quoting Randy Dunlap (randy.dunlap@xxxxxxxxxx):
> On Thu, 27 Mar 2008 10:12:27 -0500 Serge E. Hallyn wrote:
> 
> > Fill a Documentation/controllers/devices.txt file with a
> > modified text from the patch description.
> > 
> > Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
> > ---
> >  Documentation/controllers/devices.txt |   48 +++++++++++++++++++++++++++++++++
> >  1 files changed, 48 insertions(+), 0 deletions(-)
> >  create mode 100644 Documentation/controllers/devices.txt
> > 
> > diff --git a/Documentation/controllers/devices.txt b/Documentation/controllers/devices.txt
> > new file mode 100644
> > index 0000000..a157f53
> > --- /dev/null
> > +++ b/Documentation/controllers/devices.txt
> > @@ -0,0 +1,48 @@
> > +Device Whitelist Controller
> > +
> > +1. Description:
> > +
> 
> ...
> 
> > +The root device cgroup starts with rwm to 'all'.  A child devices
> 
>                                                              device's

That's actually not right, but 'child device cgroup' does sound better.

> 
> > +cgroup gets a copy of the parent.  Administrators can then remove
> > +devices from the whitelist or add new entries.  A child cgroup can
> > +never receive a device access which is denied its parent.  However
> > +when a device access is removed from a parent it will not also be
> > +removed from the child(ren).
> > +
> > +2. User Interface
> > +
> ...
> > +
> > +3. Security
> > +
> > +Any task can move itself between cgroups.  This of clearly won't
> 
> s/of//

Yup, oops.

New patch attached.  Thanks, Randy.

-serge

> > +suffice, but we can decide the best way to adequately restrict
> > +movement as people get some experience with this.  We may just want
> > +to require CAP_SYS_ADMIN, which at least is a separate bit from
> > +CAP_MKNOD.  We may want to just refuse moving to a cgroup which
> > +isn't a descendent of the current one.  Or we may want to use
> > +CAP_MAC_ADMIN, since we really are trying to lock down root.
> > +
> > +CAP_SYS_ADMIN is needed to modify the whitelist or move another
> > +task to a new cgroup.  (Again we'll probably want to change that).
> > +
> > +A cgroup may not be granted more permissions than the cgroup's
> > +parent has.  
> > -- 
> 
> ---
> ~Randy