load_policy in chroot question

Russell Coker russell at coker.com.au
Mon Feb 21 14:33:10 UTC 2005

On Tuesday 22 February 2005 00:54, Alexandre Oliva <aoliva at redhat.com> wrote:
> On Feb 19, 2005, Russell Coker <russell at coker.com.au> wrote:
> > SE Linux controls all aspects of system security, including global
> > thing such as mounting file systems and directly writing to block
> > devices.  If the chroot had a local policy as you suggest then which
> > policy would control writing to the device node for the boot device?
> Err...  No differently from the way the Xen solution you recommended
> would?  Except, perhaps, for...

Xen is totally different to a chroot.  Xen has a virtual environment which has 
it's own access controls.  The URL below concerns methods of limiting 
interaction between Xen sessions (I don't know enough about Xen to comment on 

With a chroot you might have /dev/hda1 mounted as the root file system, but 
inside the chroot the /dev/hda1 device node will still exist and grant access 
to the file system that's outside the chroot.  I believe that Xen solves this 
problem but don't know the details.

> > http://sourceforge.net/mailarchive/forum.php?thread_id=6364737&forum_id=3
> >5600
> which would require presumably yet another layer of MAC configuration
> files.  Which means yet another level of setting up and overlapping
> settings, not really different from one possible implementation for
> chroot policies.

True, it could be considered to be slightly similar in concept to a well 
implemented chroot setup.  But note that a Xen guest can't change the 
resources managed by the Xen host, and a similar level of isolation is 
required for a secure chroot.

http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
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http://www.coker.com.au/postal/    Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page

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