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From:   Kees Cook <keescook@chromium.org>
Date:   Thu, 13 Sep 2018 17:19:04 -0700
Message-ID: <CAGXu5jJ5__jdBM5X0vVyEU1TKnN4dpkXbj=10iak9RvD1DZk9g@mail.gmail.com>
Subject: Re: [PATCH 10/10] LSM: Blob sharing support for S.A.R.A and LandLock
To:     Casey Schaufler <casey@schaufler-ca.com>
Cc:     Paul Moore <paul@paul-moore.com>,
        linux-security-module <linux-security-module@vger.kernel.org>,
        James Morris <jmorris@namei.org>,
        LKML <linux-kernel@vger.kernel.org>,
        SE Linux <selinux@tycho.nsa.gov>,
        John Johansen <john.johansen@canonical.com>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Stephen Smalley <sds@tycho.nsa.gov>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        "Schaufler, Casey" <casey.schaufler@intel.com>
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On Thu, Sep 13, 2018 at 5:08 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
> On 9/13/2018 4:57 PM, Kees Cook wrote:
>> On Thu, Sep 13, 2018 at 4:51 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
>>> On 9/13/2018 4:06 PM, Kees Cook wrote:
>>>> - what order should any stacking happen? Makefile? security=?
>>> Makefile by default.
>> Okay, if ordering is by Makefile and everyone dislikes my
>> $lsm.enabled=0/1 thing, then these mean the same thing:
>>
>> security=selinux,tomoyo
>> security=tomoyo,selinux
>>
>> i.e. order of security= is _ignored_ in favor of the Makefile ordering.
>
> No, I think that the two lines above should have a different
> execution order. If we really need to specify multiple modules
> at boot time that is what makes the most sense.
>
> It's a matter of mechanics and probably another pass during the
> init process, but it's doable. If we determine it's necessary for
> this stage it is just work.

We already have the minor LSMs that cannot change order. They aren't
part of security= parsing either. To enable/disable LoadPin, you do
"loadpin.enabled=1/0" separate from "security=".

Should "blob-sharing" LSMs be like major LSMs or minor LSMs?

If someone is booting with "security=selinux,tomoyo" and then SARA
lands upstream, does that person have to explicitly add "sara" to
their boot args, since they're doing a non-default list of LSMs?

(I actually prefer the answer being "yes" here, FWIW, I just want to
nail down the expectations.)

-Kees

-- 
Kees Cook
Pixel Security