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From:   Kees Cook <keescook@chromium.org>
Date:   Fri, 5 Oct 2018 09:35:27 -0700
Message-ID: <CAGXu5jKrOWnrmEfpzH3ay2uQBsP1nmpgceWLsGRsEzZ0n4dLvw@mail.gmail.com>
Subject: Re: [PATCH security-next v4 23/32] selinux: Remove boot parameter
To:     James Morris <jmorris@namei.org>
Cc:     John Johansen <john.johansen@canonical.com>,
        Jordan Glover <Golden_Miller83@protonmail.ch>,
        Stephen Smalley <sds@tycho.nsa.gov>,
        Paul Moore <paul@paul-moore.com>,
        Casey Schaufler <casey@schaufler-ca.com>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        "Schaufler, Casey" <casey.schaufler@intel.com>,
        linux-security-module <linux-security-module@vger.kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Thu, Oct 4, 2018 at 9:58 PM, James Morris <jmorris@namei.org> wrote:
> On Thu, 4 Oct 2018, Kees Cook wrote:
>
>> On Thu, Oct 4, 2018 at 10:49 AM, James Morris <jmorris@namei.org> wrote:
>> > On Wed, 3 Oct 2018, Kees Cook wrote:
>> >> Then someone boots the system with:
>> >>
>> >> selinux=1 security=selinux
>> >>
>> >> In what order does selinux get initialized relative to yama?
>> >> (apparmor, flagged as a "legacy major", would have been disabled by
>> >> the "security=" not matching it.)
>> >
>> > It doesn't, it needs to be specified in one place.
>> >
>> > Distros will need to update boot parameter handling for this kernel
>> > onwards.  Otherwise, we will need to carry this confusing mess forward
>> > forever.
>>
>> Are you saying that you want to overrule Paul and Stephen about
>> keeping "selinux=1 secuiryt=selinux" working?
>
> Not overrule, but convince.
>
> At least, deprecate selinux=1 and security=X, but not extend it any
> further.

Okay, this is the expectation from me as well. I think my series makes
it work as-is with the new stuff just fine.

>> > In my most recent suggestion, there is no '!' disablement, just
>> > enablement.  If an LSM is not listed in CONFIG_LSM="", it's not enabled.
>>
>> And a user would need to specify ALL lsms on the "lsm=" line?
>>
>
> Yes, the ones they want enabled.
>
>> What do you think of my latest proposal? It could happily work all
>> three ways: old boot params and security= work ("selinux=1
>> security=selinux" keeps working), individual LSM enable/disable works
>> ("lsm=+loadpin"), and full LSM ordering works
>> ("lsm=each,lsm,in,order,here"):
>>
>> https://lore.kernel.org/lkml/CAGXu5jJJit8bDNvgXaFkuvFPy7NWtJW2oRWFbG-6iWk0+A1qng@mail.gmail.com/
>>
>
> I think having something like +yama will still lead to confusion.
> Explicitly stating each enabled LSM in order is totally unambiguous.
>
> If people are moving away from the distro defaults, and there is no
> high-level interface to manage this, it seems to me there's a deeper
> issue with the distro.

Okay. I will adjust the series and send a v5.

-Kees

-- 
Kees Cook
Pixel Security