+++ Matthew Garrett [01/08/19 13:42 -0700]:
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?
Hi Matthew,
If you're confident that a hard dependency is not the right approach,
then perhaps we could add a comment in the Kconfig (You could take a
look at the comment under MODULE_SIG_ALL in init/Kconfig for an
example)? If someone is configuring the kernel on their own then it'd
be nice to let them know, otherwise having a lockdown kernel without
module signatures would defeat the purpose of lockdown no? :-)
Thank you,
Jessica
