Re: [PATCH 4/9] KEYS: Allow unrestricted boot-time addition of keys to secondary keyring

David Howells
2016-11-17T09:56:07Z

Petko Manolov <petkan@mip-labs.com> wrote:

> On 16-11-16 18:11:13, David Howells wrote:
> > Allow keys to be added to the system secondary certificates keyring during
> > kernel initialisation in an unrestricted fashion. Such keys are implicitly
> > trusted and don't have their trust chains checked on link.
>
> Well, I for one do not explicitly trust these keys. I may even want to
> completely remove or replace them.

Fine be me. However, if you remove them all I would guess that you cannot
perform a secure boot.

Note that it's to be expected that the keys being loaded from the UEFI
database cannot have their signatures checked - which is why they would have
to be implicitly trusted. For the same reason, the kernel does not check the
signatures on the keys compiled into the kernel image.

> > This allows keys in the UEFI database to be added in secure boot mode for
> > the purposes of module signing.
>
> The key import should not be automatic, it should be optional.

You can argue this either way. There's a config option to allow you to turn
this on or off. Arguably, this should be split in two: one for the whitelist
(db, MokListRT) and one for the blacklist (dbx).

Further, possibly I should add an option that allows this to be restricted to
secure boot mode only.

> Same applies to the validation process.

Depends what you mean by "the validation process"? The use of secure boot at
all? The checking of signatures on keys? Module signing?

David