Comment 0 for bug 1604873

update-secureboot-policy tries to check whether MOK's override has disabled SecureBoot state. However, since the real variable in nvram is not accessible after boot, it needs to use a proxy for this information. There are two that it tries to use:
 - We've specified how shim can mirror the MokSBState variable to MokSBStateRT at boot time, to expose this information to the OS (but this is not implemented in current shim).
 - The recent kernels which honor MokSBState also include support for exposing this value as /proc/sys/kernel/moksbstate_disabled.

Neither of these is guaranteed to be present on any given system. However, if present, the kernel variable should be *unconditionally* preferred over the efi "shadow" variable - because the kernel variable is immutable, whereas MokSBStateRT is just another nvram variable that things can overwrite (though they shouldn't).

We have heard at least one report internally of a system where something other than our shim is setting the value of MokSBStateRT and confusing update-secureboot-policy, so this will be a priority to also fix in SRU.