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From:   Kees Cook <keescook@chromium.org>
Date:   Tue, 2 Oct 2018 07:44:05 -0700
Message-ID: <CAGXu5jKNzG3rGUAV39D0w4txHRG3H2qU1Z1e_b+03OgycTaWqA@mail.gmail.com>
Subject: Re: [PATCH security-next v4 23/32] selinux: Remove boot parameter
To:     Stephen Smalley <sds@tycho.nsa.gov>
Cc:     Paul Moore <paul@paul-moore.com>, James Morris <jmorris@namei.org>,
        Casey Schaufler <casey@schaufler-ca.com>,
        John Johansen <john.johansen@canonical.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 Tue, Oct 2, 2018 at 6:42 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
> On 10/02/2018 08:12 AM, Paul Moore wrote:
>>
>> On Mon, Oct 1, 2018 at 9:04 PM Kees Cook <keescook@chromium.org> wrote:
>>>
>>> Since LSM enabling is now centralized with CONFIG_LSM_ENABLE and
>>> "lsm.enable=...", this removes the LSM-specific enabling logic from
>>> SELinux.
>>>
>>> Signed-off-by: Kees Cook <keescook@chromium.org>
>>> ---
>>>   .../admin-guide/kernel-parameters.txt         |  9 ------
>>>   security/selinux/Kconfig                      | 29 -------------------
>>>   security/selinux/hooks.c                      | 15 +---------
>>>   3 files changed, 1 insertion(+), 52 deletions(-)
>>>
>>> diff --git a/Documentation/admin-guide/kernel-parameters.txt
>>> b/Documentation/admin-guide/kernel-parameters.txt
>>> index cf963febebb0..0d10ab3d020e 100644
>>> --- a/Documentation/admin-guide/kernel-parameters.txt
>>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>>> @@ -4045,15 +4045,6 @@
>>>                          loaded. An invalid security module name will be
>>> treated
>>>                          as if no module has been chosen.
>>>
>>> -       selinux=        [SELINUX] Disable or enable SELinux at boot time.
>>> -                       Format: { "0" | "1" }
>>> -                       See security/selinux/Kconfig help text.
>>> -                       0 -- disable.
>>> -                       1 -- enable.
>>> -                       Default value is set via kernel config option.
>>> -                       If enabled at boot time, /selinux/disable can be
>>> used
>>> -                       later to disable prior to initial policy load.
>>
>>
>> No comments yet on the rest of the patchset, but the subject line of
>> this patch caught my eye and I wanted to comment quickly on this one
>> ...
>>
>> Not a fan unfortunately.
>>
>> Much like the SELinux bits under /proc/self/attr, this is a user
>> visible thing which has made its way into a lot of docs, scripts, and
>> minds; I believe removing it would be a big mistake.
>
>
> Yes, we can't suddenly break existing systems that had selinux=0 in their
> grub config.  We have to retain the support.

Is it okay to only support selinux=0 (instead of also selinux=1)?

-Kees

-- 
Kees Cook
Pixel Security