Re: [PATCH v5 00/21] EVM

David Safford
2011-05-26T18:12:12Z

On Thu, 2011-05-26 at 09:34 -0700, Casey Schaufler wrote:
> On 5/25/2011 11:08 PM, Pavel Machek wrote:
> > ...
> > Fourthly, is it likely to find its way to the next cellphone I buy,
> > and will it prevent me from rooting it?
> > Pavel
>
> That will of course depend on the phone vendor. You are certainly
> going to be able to vote with your checkbook (digital wallet?) but
> odds are pretty good that should EVM prove effective it will be
> ubiquitous within the next five years on embedded devices.

um, not quite the right threat model...

Rooting is normally done through an exploit of the loader
or the kernel, neither of which EVM can prevent. The phones
which have blocked rooting in hardware have done so by adding
and enforcing digital signatures on the boot images, which is
entirely orthogonal to EVM.

Whether or not the phone is rooted, IMA-Appraisal, EVM, and
the Digital Signature Extensions help protect against remote
software attacks, and offline hardware attacks on individual
files, but not against rooting itself.

dave
(happy owner of a rooted Droid)