On Wed, Aug 28, 2013 at 3:58 PM, Lenny Szubowicz <lszubowi@xxxxxxxxxx> wrote: > > > ----- Original Message ----- >> From: "Matthew Garrett" <matthew.garrett@xxxxxxxxxx> >> To: "Lenny Szubowicz" <lszubowi@xxxxxxxxxx> >> Cc: linux-kernel@xxxxxxxxxxxxxxx, linux-efi@xxxxxxxxxxxxxxx, jwboyer@xxxxxxxxxx, keescook@xxxxxxxxxxxx >> Sent: Wednesday, August 28, 2013 6:41:55 PM >> Subject: Re: [PATCH 0/10] Add additional security checks when module loading is restricted >> >> On Wed, 2013-08-28 at 18:37 -0400, Lenny Szubowicz wrote: >> >> > Did you purposely exclude similar checks for hibernate that were covered >> > by earlier versions of your patch set? >> >> Yes, I think it's worth tying it in with the encrypted hibernation >> support. The local attack is significantly harder in the hibernation >> case - in the face of unknown hardware it basically involves a >> pre-generated memory image corresponding to your system or the ability >> to force a reboot into an untrusted environment. I think it's probably >> more workable to just add a configuration option for forcing encrypted >> hibernation when secure boot is in use. >> >> -- >> Matthew Garrett <matthew.garrett@xxxxxxxxxx> > > I'm root. So I can write anything I want to the swap file that looks > like a valid hibernate image but is code of my choosing. I can read > anything I need from /dev/mem or /dev/kmem to help me do that. > I can then immediately initiate a reboot. Strictly speaking, RAM contents are not available via /dev/*mem, even to root. However, you can request a suspend image be written, but to not enter hibernation. Then modify the image, and request a resume from it. -Kees -- Kees Cook Chrome OS Security -- 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
