Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH 16/18] LSM: Allow arbitrary LSM ordering
To:     Kees Cook <keescook@chromium.org>,
        Casey Schaufler <casey@schaufler-ca.com>
Cc:     James Morris <jmorris@namei.org>,
        John Johansen <john.johansen@canonical.com>,
        Paul Moore <paul@paul-moore.com>,
        Stephen Smalley <sds@tycho.nsa.gov>,
        "Schaufler, Casey" <casey.schaufler@intel.com>,
        LSM <linux-security-module@vger.kernel.org>,
        LKLM <linux-kernel@vger.kernel.org>
References: <20180916003059.1046-1-keescook@chromium.org>
 <20180916003059.1046-17-keescook@chromium.org>
 <84e1a5a8-8997-829f-cf09-1d29895a3f99@schaufler-ca.com>
 <CAGXu5jK5CzXUii97q_yk3KzBTw0SOmoc=-zcm+3jAqEHe76AgQ@mail.gmail.com>
From:   Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Message-ID: <e6e7521f-7810-a938-3f0e-daefb6579344@i-love.sakura.ne.jp>
Date:   Mon, 17 Sep 2018 09:46:58 +0900
User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.9.1
MIME-Version: 1.0
In-Reply-To: <CAGXu5jK5CzXUii97q_yk3KzBTw0SOmoc=-zcm+3jAqEHe76AgQ@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 2018/09/17 8:00, Kees Cook wrote:
> On Sun, Sep 16, 2018 at 11:49 AM, Casey Schaufler
> <casey@schaufler-ca.com> wrote:
>> One solution is to leave security= as is, not affecting "minor"
>> modules and only allowing specification of one major module, and adding
> 
> I would much prefer this, yes.
> 
> A question remains: how do we map the existing "security=" selection
> of a "major" LSM against what will be next "exclusive" plus tomoyo,
> and in the extreme case, nothing?
> 
> Perhaps as part of deprecating "security=", we could just declare that
> it is selecting between SELinux, AppArmor, Smack, and Tomoyo only?
> 
>> another boot option security.stack= that overrides a security= option
>> and that takes the list as you've implemented here.
> 
> or "lsm.stack=" that overrides "security=" entirely?


Yes, I think we can add new option.

For example, introducing lsm= and obsoleting security= (because total length for
kernel command line is limited while enumeration makes the parameter value longer).

  security= works like current behavior.

  lsm= requires explicit enumeration of all modules (except capability which has to
  be always enabled) which should be enabled at boot.

  security= is ignored if lsm= is specified.