Messages in this thread | | | Date | Thu, 26 Sep 2013 08:24:41 +0200 (CEST) | From | Jiri Kosina <> | Subject | Re: [RFC V4 PATCH 00/15] Signature verification of hibernate snapshot |
| |
On Wed, 25 Sep 2013, James Bottomley wrote:
> > I don't get this. Why is it important that current kernel can't > > recreate the signature? > > The thread model is an attack on the saved information (i.e. the suspend > image) between it being saved by the old kernel and used by the new one. > The important point isn't that the new kernel doesn't have access to > K_{N-1} it's that no-one does: the key is destroyed as soon as the old > kernel terminates however the verification public part P_{N-1} survives.
James,
could you please describe the exact scenario you think that the symmetric keys aproach doesn't protect against, while the assymetric key aproach does?
The crucial points, which I believe make the symmetric key aproach work (and I feel quite embarassed by the fact that I haven't realized this initially when coming up with the assymetric keys aproach) are:
- the kernel that is performing the actual resumption is trusted in the secure boot model, i.e. you trust it to perform proper verification
- potentially malicious userspace (which is what we are protecting against -- malicious root creating fake hibernation image and issuing reboot) doesn't have access to the symmetric key
-- Jiri Kosina SUSE Labs
| |