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Re: Updated Secure Boot docs in the wiki



On Sun, 2019-03-31 at 12:05 +0100, Luca Boccassi wrote:
> On Sun, 2019-03-31 at 07:18 +0100, Steve McIntyre wrote:
> > Hey folks,
> > 
> > I've extended and updated Lucas' initial SB page:
> > 
> >   
> > https://wiki.debian.org/SecureBoot
> > 
> > 
> > to cover a lot more user-facing stuff. Please review...
> 
> Hi,
> 
> That looks great, thanks!
> 
> Just one minor note:
> 
> "This will block out-of-tree modules and DKMS-managed drivers like
> binary !NVidia graphics drivers. Again, you will need to disable SB
> or
> use and enrol your own key to make things work."
> 
> AFAIK enrolling own key for kernel modules does not work in Debian as
> of now, as the kernel does not import keys from DB/MOK into the
> keyring
> at boot, so only keys embedded at the kernel's build time are used to
> validate modules.
> 
> There's a patch to enabled that feature shipped in Ubuntu/RHEL, and
> IIRC something was proposed upstream but as of now nothing is merged:
> 
> https://lkml.org/lkml/2016/11/16/527
> 
> https://lkml.org/lkml/2018/2/28/1089
> 
> 
> (I think Ubuntu/RHEL carry patches from the former set to enable this
> feature)

I have successfully tested porting the patches from the former set, and
opened a MR for review on Salsa:

https://salsa.debian.org/kernel-team/linux/merge_requests/139

With this, the key added to MOK can be used to verify kernel modules,
so I am able to use bbswitch/nvidia on my optimus laptop with secure
boot enabled.

I tried the latter patchset, which got merged upstream as this series:
https://lkml.org/lkml/2018/12/8/218
But it requires IMA, which we disable as it doesn't quite work with the
lockdown set, and it's only for kexec at the moment, not for modules.

-- 
Kind regards,
Luca Boccassi

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