Re: [PATCH V37 04/29] Enforce module signatures if the kernel is locked down

[Matthew Garrett]

On Thu, Aug 1, 2019 at 7:22 AM Jessica Yu <jeyu@xxxxxxxxxx> wrote:
> Apologies if this was addressed in another patch in your series (I've
> only skimmed the first few), but what should happen if the kernel is
> locked down, but CONFIG_MODULE_SIG=n? Or shouldn't CONFIG_SECURITY_LOCKDOWN_LSM
> depend on CONFIG_MODULE_SIG? Otherwise I think we'll end up calling
> the empty !CONFIG_MODULE_SIG module_sig_check() stub even though
> lockdown is enabled.

Hm. Someone could certainly configure their kernel in that way. I'm
not sure that tying CONFIG_SECURITY_LOCKDOWN_LSM to CONFIG_MODULE_SIG
is the right solution, since the new LSM approach means that any other
LSM could also impose the same policy. Perhaps we should just document
this?