Re: [atomic-devel] Kubeadm vs. SELinux

[Daniel J Walsh <dwalsh redhat com>]

On 11/23/2016 10:34 AM, Devan Goodwin wrote:
> On Wed, Nov 23, 2016 at 9:42 AM, Daniel J Walsh <dwalsh redhat com> wrote:
>>
>> On 11/22/2016 07:26 PM, Josh Berkus wrote:
>>> On 11/22/2016 03:27 PM, Clayton Coleman wrote:
>>>> Copying Devan as well since he's been working with kubeadm for a while.
>>>>
>>>>> On Nov 22, 2016, at 5:25 PM, Jason Brooks <jbrooks redhat com> wrote:
>>>>>
>>>>>> On Tue, Nov 22, 2016 at 2:38 PM, Daniel J Walsh <dwalsh redhat com> wrote:
>>>>>>
>>>>>>
>>>>>>> On 11/22/2016 05:15 PM, Josh Berkus wrote:
>>>>>>> Currently, it is not possible to run Kubeadm with SELinux enabled.
>>>>>>>
>>>>>>> This is bad; it means that Kubernetes' official installation
>>>>>>> instructions include `setenforce 0`.  But it's hard to argue the point
>>>>>>> when a kubeadm install -- soon to be the main install option for
>>>>>>> Kubernetes, and the only one which currently works on Atomic -- simply
>>>>>>> doesn't work with SELinux enabled.
>>>>>>>
>>>>>>> The current blocker is that kubeadm init will hang forever at this stage:
>>>>>>>
>>>>>>> <master/apiclient> created API client, waiting for the control plane to
>>>>>>> become ready
>>>>>>>
>>>>>>>
>>>>>>> The errors shown in the journal are here:
>>>>>>>
>>>>>>> https://gist.github.com/jberkus/4e926c76fbf772ffee4eb774cb0a4c60
>>>>>>>
>>>>>>> That's on Fedora 25 Atomic.  I've had the exact same experience on
>>>>>>> CentOS 7 and RHEL 7, although the error messages are not identical.
>>>>>>>
>>>>>>> Seems like this is on us to fix, if we want people to keep SELinux
>>>>>>> enforcing. I don;t know if we need to push patches to Kubeadm, or to
>>>>>>> SELinux, or both.
>>>>>>>
>>>>>> What AVC's are you seeing?  Where is the bugzilla for this?
>>>>>>
>>>>>> ausearch -m avc -ts recent
>>>>> https://paste.fedoraproject.org/488671/79856867/
>>>>>
>>>>> This is from a kubeadm that's packaged up in a copr:
>>>>> https://copr.fedorainfracloud.org/coprs/jasonbrooks/kube-release/
>>>>>
>>>>> The kubernetes project provides rpms for centos and ubuntu, and there
>>>>> are a few things about the way they pkg it that conflict w/ atomic.
>>>>> Some more info at
>>>>> https://jebpages.com/2016/11/01/installing-kubernetes-on-centos-atomic-host-with-kubeadm/.
>>>>>
>>> In addition to this, please note that setenforce 0 is not required on
>>> the workers nodes, just on the master.  The kubelet nodes work fine with
>>> just relabeling the /var/lib/kubelet directory.
>>>
>>> It would be really nice if we could somehow do that relabeling as part
>>> of the installation package, but I don't see how; it would need to be a
>>> patch/fork on kubeadm instead.
>>>
>>>
>> Relabeling of /var/lib/kublet should not be necessary either.  What
>> label is being applied?  What AVC's show up when it is
>> not applied?
>>
>> Just setting random labels has the potential for opening security
>> holes.   We need to get this directory labeled in such
>> a way that not all containers can read/write it.
>
> Is this relabeling only required on Atomic?
I don't see why.  The problem might be that the k8s is not passing the
:Z, :z flag to docker when mounting
volumes into a container

docker run -v /var/lib/kublet/.../foobar:/var/lib/foobar:Z ...

Causes docker daemon to relabel the content under
/var/lib/kublet.../foobar with the correct container label.
This container label would prevent other containers from using the content.