On Mon, Jun 15, 2015 at 09:37:05AM -0400, Josh Boyer wrote: > The bits that actually read Secure Boot state out of the UEFI > variables, and apply protections to the machine to avoid compromise > under the SB threat model. Things like disabling the old kexec... I don't have any real interest in using Secure Boot, but I *am* interested in using CONFIG_KEXEC_VERIFY_SIG[1]. So perhaps we need to have something similar to what we have with signed modules in terms of CONFIG_MODULE_SIG_FORCE and module/sig_enforce, but for KEXEC_VERIFY_SIG. This would mean creating a separate flag independent of the one Linus suggested for Secure Boot, but since we have one for signed modules, we do have precedent for this sort of thing. - Ted [1] Yes, it doesn't buy all that much, since if the system is rooted the adversary can just replace the kernel in /boot and force a normal, slower reboot, but the same could be said for signed modules --- the adversary could just replace all of /boot/vmlinux-<kver> and /lib/modules/<kver>. But both measures make it a tad more bit difficult, especially for the adversary to do this replacement without being noticed (for example linode will send me e-mail if the system reboots normally, but not with a kexec-mediated reboot), and for cloud systems where we don't have secure boot anyway, it's about the best we can do.
