[PATCH] lsm: drop LSM_ID_IMA

[Paul Moore]

On Wed, Oct 25, 2023 at 10:06 AM Roberto Sassu
<roberto.sassu at huaweicloud.com> wrote:
> On 10/25/2023 3:14 PM, Paul Moore wrote:
> > On Wed, Oct 25, 2023 at 6:36 AM Roberto Sassu
> > <roberto.sassu at huaweicloud.com> wrote:
> >> On 10/24/2023 11:18 PM, Paul Moore wrote:
> >>> On Mon, Oct 23, 2023 at 11:48 AM Casey Schaufler <casey at schaufler-ca.com> wrote:
> >>>> On 10/23/2023 8:20 AM, Roberto Sassu wrote:
> >>>>> On 10/20/2023 11:56 PM, Casey Schaufler wrote:
> >>>>>> On 10/19/2023 1:08 AM, Roberto Sassu wrote:
> >>>>>>> On Wed, 2023-10-18 at 17:50 -0400, Paul Moore wrote:
> >>>>>>>> When IMA becomes a proper LSM we will reintroduce an appropriate
> >>>>>>>> LSM ID, but drop it from the userspace API for now in an effort
> >>>>>>>> to put an end to debates around the naming of the LSM ID macro.
> >>>>>>>>
> >>>>>>>> Signed-off-by: Paul Moore <paul at paul-moore.com>
> >>>>>>> Reviewed-by: Roberto Sassu <roberto.sassu at huawei.com>
> >>>>>>>
> >>>>>>> This makes sense according to the new goal of making 'ima' and 'evm' as
> >>>>>>> standalone LSMs.
> >>>>>>>
> >>>>>>> Otherwise, if we took existing LSMs, we should have defined
> >>>>>>> LSM_ID_INTEGRITY, associated to DEFINE_LSM(integrity).
> >>>>>>>
> >>>>>>> If we proceed with the new direction, I will add the new LSM IDs as
> >>>>>>> soon as IMA and EVM become LSMs.
> >>>>>>
> >>>>>> This seems right to me. Thank You.
> >>>>>
> >>>>> Perfect! Is it fine to assign an LSM ID to 'ima' and 'evm' and keep
> >>>>> the 'integrity' LSM to reserve space in the security blob without LSM
> >>>>> ID (as long as it does not register any hook)?
> >>>>
> >>>> That will work, although it makes me wonder if all the data in the 'integrity' blob
> >>>> is used by both IMA and EVM. If these are going to be separate LSMs they should probably
> >>>> have their own security blobs. If there is data in common then an 'integrity' blob can
> >>>> still makes sense.
> >>>
> >>> Users interact with IMA and EVM, not the "integrity" layer, yes?  If
> >>> so, I'm not sure it makes sense to have an "integrity" LSM, we should
> >>> just leave it at "IMA" and "EVM".
> >>
> >> The problem is who reserves and manages the shared integrity metadata.
> >> For now, it is still the 'integrity' LSM. If not, it would be IMA or EVM
> >> on behalf of the other (depending on which ones are enabled). Probably
> >> the second would not be a good idea.
> >
> > I'm not certain that managing kernel metadata alone necessitates a LSM
> > ID token value.  Does "integrity" have any user visible "things" that
> > it would want to expose to userspace?
>
> No, it doesn't. I already moved the LSM hook registration to 'ima' and
> 'evm'. Also the old 'integrity' initialization is done by 'ima' and 'evm'.
>
> DEFINE_LSM(integrity) exists only to reserve space in the security blob
> and to provide the security blob offset to the get/set functions.
>
> Maybe I send the patch set, so that you get a better idea.

If it isn't a big ask, sure, but I still need to get through the last
patchset you posted.  I do apologize for the delay on that, things
seem to be very busy recently.

-- 
paul-moore.com