[PATCH v7 0/6] Safe LSM (un)loading, and immutable hooks

Sargun Dhillon sargun at sargun.me
Mon Apr 30 18:25:37 UTC 2018

On Mon, Apr 30, 2018 at 9:46 AM, Casey Schaufler <casey at schaufler-ca.com> wrote:
> On 4/30/2018 9:11 AM, Sargun Dhillon wrote:
>> On Sun, Apr 29, 2018 at 2:23 PM, Casey Schaufler <casey at schaufler-ca.com> wrote:
>>> On 4/29/2018 4:49 AM, Tetsuo Handa wrote:
>>>> Casey Schaufler wrote:
>>>>> I think that we're on the verge of having a major merge collision.
>>>> I think that the reason of major merge collision is that your patchset is
>>>> too big to review.
>>> My patch set is large because it has to address all of the
>>> aspects of multiple modules running on the system before some
>>> important members of the community will look at it seriously.
>>>>   > That's a lot of overhead. The smaller the patches, the more work
>>>>   > required to make the patch set. You're right that the current patches
>>>>   > are too big. Moving forward I will be providing smaller, easier to
>>>>   > deal with patches. The sheer overhead of rebaseing a large patch set
>>>>   > has slowed down the development considerably. Minions. What I need are
>>>>   > minions.
>>>> You are holding the global lock for patchset which you did not get response.
>>>> If you agree with breaking into smaller patches, we will be able to solve
>>>> the major merge collision.
>>> I will be presenting the set of smaller patches once I finish merging
>>> them into 4.18. It's a bigger jobs than usual because of the change from
>>> lists to hlists, the significant changes to AppArmor and the early stages
>>> of SELinux namespacing. I hope to have it done mid week, but the changes
>>> need to get tested, and there are lots of configurations involved.
>>> I am perfectly amenable to the patches going in in logical stages.
>>> In fact, that is what I would recommend.
>> I guess I'm just a little bit frustrated, because, in my mind, some of
>> my patches provide immediate value, and are ready to be reviewed, and
>> or respun. Testuo did a good job reviewing 1-5, and I think that if
>> those are his only issues, then we're good to go.
>> I've:
>> 1) Do safe hook loading for sane security modules (those that don't
>> try to overload major hooks), without compromising the security of
>> other hooks
>> 2) Suggested a whitelist of major hooks to prevent insane modules from
>> being loaded
>> If Casey's patches land, we can just not do (2), and we're good to go.
> I understand your frustration. As much as I would like to
> avoid having the stacking work take any longer than it already
> has (I *do* have a boatload of other stuff I want to get done)
> I suggest that if you can get consensus that the lkm-based
> security module work should be accepted that you go forward and
> get it in. I know that I have at least one major round of review
> before the stacking can really be seriously considered. I knew
> the job was dangerous when I took it.
Curious, consensus from whom? I thought you owned this part of the tree.
>>>>> ...
>> One dumb use case I have is the ability to limit interactions with
>> PTYs for containerized applications. Another aspect of this is being
>> able to write policies in C, and actually being able to control the
>> nitty gritty of what's going on, versus actively fighting with the
>> LSM(s).
> You don't need lkm-based modules to do that, but I can see
> why you might want to do it that way. It's also something that
> I would expect LandLock to be a solution for, but again you'd
> need to be running LandLock when you identified the issue.
I've been a long-time proponent of programmable LSMs (before it was
cool): https://lkml.org/lkml/2016/8/4/58

Do you know where Landlock is in terms of getting merged?
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