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From:   Kees Cook <keescook@chromium.org>
Date:   Tue, 14 Aug 2018 22:19:22 -0700
Message-ID: <CAGXu5jJ6Ngv8A=3TV5z5+x5kCkkXwjYtDfSQjUQgscP4hv_xYg@mail.gmail.com>
Subject: Re: [PATCH v1 00/22] LSM: Full security module stacking
To:     Casey Schaufler <casey@schaufler-ca.com>
Cc:     Jordan Glover <Golden_Miller83@protonmail.ch>,
        Sargun Dhillon <sargun@sargun.me>,
        LSM <linux-security-module@vger.kernel.org>,
        LKLM <linux-kernel@vger.kernel.org>,
        Paul Moore <paul@paul-moore.com>,
        Stephen Smalley <sds@tycho.nsa.gov>,
        SE Linux <selinux@tycho.nsa.gov>,
        "SMACK-discuss@lists.01.org" <SMACK-discuss@lists.01.org>,
        John Johansen <john.johansen@canonical.com>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        James Morris <jmorris@namei.org>,
        "Schaufler, Casey" <casey.schaufler@intel.com>,
        Salvatore Mesoraca <s.mesoraca16@gmail.com>,
        =?UTF-8?B?TWlja2HDq2wgU2FsYcO8bg==?= <mic@digikod.net>
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On Tue, Aug 14, 2018 at 4:50 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
> On 8/14/2018 4:22 PM, Jordan Glover wrote:
>> On August 14, 2018 8:28 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
>>
>>>
>>>>> The blob management part (through "LSM: Sharing of security blobs")
>>>>> is ready for prime-time. These changes move the management of
>>>>> security blobs out of the security modules and into the security
>>>>> module infrastructure. With this change the proposed S.A.R.A,
>>>>> LandLock and PTAGS security modules could co-exist with any of
>>>>> the existing "major" security modules. The changes reduce some
>>>>> code duplication.
>>>>> Beyond the blob management there's a bit of clean-up.
>>>>> Mounting filesystems had to be changed so that options
>>>>> a security module doesn't recognize won't be considered
>>>>> a fatal error. The mount infrastructure is somewhat
>>>>> more complex than one might assume.
>>>> Casey,
>>>> Do you think you can break out 1 into its own patch? It seems like
>>>> that'd be valuable to everyone.
>>> Yes, I think that is a good idea. Landlock, S.A.R.A. and a couple
>>> other security modules could be added upstream if this part of the
>>> work was available. It would not provide everything needed to stack
>>> all the existing modules. I believe there is concern that if this
>>> much went upstream the work on finishing what's required to make
>>> everything work might be abandoned.
>>>
>> On the other hand there is concern that those security modules might
>> be abandoned if they have to wait until everything is finished :)
>
> There is some truth to that. If we can get commitment from the developers
> of those security module to push for getting upstream, a statement of
> intent to support additional modules (e.g. Landlock, S.A.R.A.) from a
> significant distribution (e.g. Fedora, Ubuntu, SuSE) and ACKs from the
> maintainers of the existing modules we should be able to breeze right in.
>
> Yeah, I think that's about all it would take.

I would strongly recommend Landlock and SARA for every distro. They're
opt-in, and provide much-needed missing userspace defenses (and attack
surface reduction).

-Kees

-- 
Kees Cook
Pixel Security