(Cc'ing Peter A. and Peter J. for boot params discussion) On Wed, 11 Jan, at 03:27:23PM, David Howells wrote: > Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> wrote: > > > > + movb $0, BP_secure_boot(%rsi) > > > #ifdef CONFIG_EFI_STUB > > > /* > > > * The entry point for the PE/COFF executable is efi_pe_entry, so > > > > Is clearing ::secure_boot really necessary? Any code path that goes > > via efi_main() will set it correctly and all other code paths should > > get it cleared in sanitize_boot_params(), no? > > No. > > The boot_params->secure_boot parameter exists whether or not efi_main() is > traversed (ie. if EFI isn't enabled or CONFIG_EFI_STUB=n) and, if not cleared, > is of uncertain value. > > Further, sanitize_boot_params() has to be modified by this patch so as not to > clobber the secure_boot flag. Any new parameters that boot loaders do not know about should be cleared to zero by default in the boot loader because boot_params itself should be zero'd when allocated. There are two cases to consider: 1) boot_params is not zero'd 2) boot_params is zero'd 1) This is a broken boot loader implementation that violates the x86 boot specification and I would never expect ->secure_boot to have a valid value. It should not be special-cased in sanitize_boot_params(), it should be zero'd. 2) In this case ->secure_boot should be zero unless modified inside of efi_main(). Did you hit the scenario where ->secure_boot has a garbage value while developing these patches? I wouldn't expect to see it in practice. -- 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
