On 10/31/2012 02:14 PM, Oliver Neukum wrote:
On Wednesday 31 October 2012 17:39:19 Alan Cox wrote:
On Wed, 31 Oct 2012 17:17:43 +0000
Matthew Garrett<mjg59@xxxxxxxxxxxxx> wrote:
On Wed, Oct 31, 2012 at 05:21:21PM +0000, Alan Cox wrote:
On Wed, 31 Oct 2012 17:10:48 +0000
Matthew Garrett<mjg59@xxxxxxxxxxxxx> wrote:
The kernel is signed. The kernel doesn't check the signature on the
suspend image.
Which doesn't matter. How are you going to create the tampered image in
the first place ?
By booting a signed kernel, not turning on swap and writing directly to
the swap partition.
Ok so the actual problem is that you are signing kernels that allow the
user to skip the S4 resume check ?
No. The problem is principal in nature.
swapoff /dev/sdb6 ; dd if=/tmp/malicious_image of=/dev/sdb6 ; sync ; reboot
That would do it on my system.
Maybe in theory you could solve this by the kernel invalidating images
it hasn't written itself and forbidding to change the resume partition from the
kernel command line, but that would break user space hibernation.
If the resuming kernel refuses to resume from images it didn't create
itself, why do you need to forbid changing the resume partition from the
kernel command line?
Chris
--
To unsubscribe from this list: send the line "unsubscribe linux-efi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
