* Matthew Garrett: > On Thu, Feb 28, 2013 at 08:41:13PM +0100, Florian Weimer wrote: >> * Matthew Garrett: >> >> >> Would it be possible to have a signed bootloader that allows booting >> >> Win8 from within the secure environment, or it could exit the secure >> >> environment and run unsigned grub? >> > >> > What would stop the unsigned grub from installing a firmware hook that >> > lies about whether or not Secure Boot is enabled, and then booting >> > Windows? >> >> Windows would not have access to the product key because it is stored >> in a variable without EFI_VARIABLE_RUNTIME_ACCESS, so WGA and other >> checks will fail, and the user will notice. > > grub's running before ExitBootServices(), because otherwise it has no > way to actually read anything off disk. Or draw to the screen.
Sorry, if Linux can read from the disk after ExitBootServices(), so can a boot loader. Actually, we could boot Linux directly, with an initrd which contains a boot selector, and use kexec if the chosen kernel doesn't match the initial one. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
