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From:   Kees Cook <keescook@chromium.org>
Date:   Thu, 4 Oct 2018 17:05:09 -0700
Message-ID: <CAGXu5j+3HqqBa_ogQqGJYubeZr9uCrbKzEoKO3Or=71e4c_=Gw@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 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?

>> CONFIG_LSM="yama,apparmor,!selinux"
>>
>> to mean "put selinux here in the order, but don't enable it". Then the
>> problem becomes what happens to an LSM that has been built in but not
>> listed in CONFIG_LSM?
>
> 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?

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/

-Kees

-- 
Kees Cook
Pixel Security