Re: [RFC PATCH 2/2] kexec, KEYS: Make use of platform keyring for signature verify

[Mimi Zohar]

On Sun, 2019-01-13 at 09:39 +0800, Dave Young wrote:
> Hi,
> 
> On 01/11/19 at 11:13am, Mimi Zohar wrote:
> > On Fri, 2019-01-11 at 21:43 +0800, Dave Young wrote:
> > [snip]
> > 
> > > Personally I would like to see platform key separated from integrity.
> > > But for the kexec_file part I think it is good at least it works with
> > > this fix.
> > > 
> > > Acked-by: Dave Young <dyoung@xxxxxxxxxx>
> > 
> > The original "platform" keyring patches that Nayna posted multiple
> > times were in the certs directory, but nobody commented/responded. ÂSo
> > she reworked the patches, moving them to the integrity directory and
> > posted them (cc'ing the kexec mailing list). ÂIt's a bit late to be
> > asking to move it, isn't it?
> 
> Hmm, apologize for being late,  I did not get chance to have a look the
> old series.  Since we have the needs now, it should be still fine
> 
> Maybe Kairui can check Nayna's old series, see if he can do something
> again?

Whether the platform keyring is defined in certs/ or in integrity/ the
keyring id needs to be accessible to the other, without making the
keyring id global. ÂMoving where the platform keyring is defined is
not the problem.

Commit a210fd32a46b ("kexec: add call to LSM hook in original
kexec_load syscall") introduced a new LSM hook. ÂAssuming
CONFIG_KEXEC_VERIFY_SIG is enabled, with commit b5ca117365d9 ("ima:
prevent kexec_load syscall based on runtime secureboot flag") we can
now block the kexec_load syscall. ÂWithout being able to block the
kexec_load syscall, verifying the kexec image signature via the
kexec_file_load syscall is kind of pointless.

Unless you're planning on writing an LSM to prevent the kexec_load
syscall, I assume you'll want to enable integrity anyway.

Mimi