Re: AppArmor Security Goal

[John Johansen]

On Mon, Nov 12, 2007 at 03:50:59PM -0800, Crispin Cowan wrote:
> Dr. David Alan Gilbert wrote:
> > * Crispin Cowan (crispin@xxxxxxxxxxxxxxxx) wrote:
> >   
> >> I mostly don't see this as a serious limitation, because almost everyone
> >> has their own workstation, and thus has root on that workstation. There
> >> are 2 major exceptions:
> >>
> >>     * Schools, where the "workstations" are thin client X terminals and
> >>       everyone is logged into a giant shared machine. Sorry, AppArmor is
> >>       not a good choice for that environment, but it is a pretty scarce
> >>       environment.
> >>     * Enterprises, where workers get their own workstation, but they
> >>       don't get root. Well, the reason the worker doesn't get root is
> >>       the enterprise doesn't trust them with it, and so not letting them
> >>       edit security policy is probably a good idea.
> >>     
> > I don't actually see your distinction here between those two environments;
> > why does it matter if there is one non-priveliged user or many?
> >   
> Because it is easier to solve if there is only one non-privileged user:
> you just give them privilege (fun with chmod and sudo) to edit the
> system policies, and you're done (assuming you are happy allowing the
> non-privileged user to edit policy at all).
> 
> If there are lots of non-privileged users sharing a computer, then I
> submit that solutions are either insecure, intractable, or purely
> restrictive.
> 
yep, it needs to be purely restrictive

> >> Can you explain why you want a non-privileged user to be able to edit
> >> policy? I would like to better understand the problem here.
> >>     
> > I think it might depend on how strict the users starting point is;
> > you could say:
> >    1 This document editor can read and write any part of the users home
> >      directory other than the . files.
> >
> > or you could say:
> >    2 This document editor can read any files but only write to the
> >      'Documents directory'.
> >
> > If the adminisrator set something up with (2) as the starting point it
> > would seem reasonable for the user to be able to add the ability to edit
> > documents in extra directories for their style of organising documents
> > they work on; but they would be restricted in what they could add
> > so that they couldn't add the ability to write to their settings
> > files.
> >   
> Ok, I can see where that would be useful in theory. But solving it is
> VERY hard in practice, and AppArmor is not attempting to address this
> problem of user extensibility of mandatory access controls.
> 
Well at least its not on Crispin's list.  It is something I have been
interested in for a long time.  I can't say when or it will happen
as I need to find some, ever elusive, spare time to work on it.

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