Re: [RFC Part1 PATCH 00/20 v2] Add namespace support for audit

Gao feng
2013-12-24T09:32:22Z

On 12/21/2013 05:15 AM, Serge E. Hallyn wrote:
> Quoting Gao feng (gaofeng-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org):
>> On 12/11/2013 04:36 AM, Serge E. Hallyn wrote:
>>> Quoting Eric Paris (eparis-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org):
>>>> On Tue, 2013-12-10 at 10:51 -0600, Serge Hallyn wrote:
>>>>> Quoting Gao feng (gaofeng-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org):
>>>>>> On 12/10/2013 02:26 AM, Serge Hallyn wrote:
>>>>>>> Quoting Gao feng (gaofeng-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org):
>>>>>>>> On 12/07/2013 06:12 AM, Serge E. Hallyn wrote:
>>>>>>>>> Quoting Gao feng (gaofeng-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org):
>>>>>>>>>> Hi
>>>>>>>>>>
>>>>>>>>>> On 10/24/2013 03:31 PM, Gao feng wrote:
>>>>>>>>>>> Here is the v1 patchset: http://lwn.net/Articles/549546/
>>>>>>>>>>>
>>>>>>>>>>> The main target of this patchset is allowing user in audit
>>>>>>>>>>> namespace to generate the USER_MSG type of audit message,
>>>>>>>>>>> some userspace tools need to generate audit message, or
>>>>>>>>>>> these tools will broken.
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> I really need this feature, right now,some process such as
>>>>>>>>>> logind are broken in container becase we leak of this feature.
>>>>>>>>>
>>>>>>>>> Your set doesn't address loginuid though right? How exactly do you
>>>>>>>>> expect to do that? If user violates MAC policy and audit msg is
>>>>>>>>> sent to init user ns by mac subsys, you need the loginuid from
>>>>>>>>> init_audit_ns. where will that be stored if you allow updates
>>>>>>>>> of loginuid in auditns?
>>>>>>>>>
>>>>>>>> This patchset doesn't include the loginuid part.
>>>>>>>>
>>>>>>>> the loginuid is stored in task as before.
>>>>>>>> In my opinion, when task creates a new audit namespace, this task's
>>>>>>>> loginuid will be reset to zero, so the children tasks can set their
>>>>>>>> loginuid. Does this change break the MAC?
>>>>>>>
>>>>>>> I think so, yes. In an LSPP selinux environment, if the task
>>>>>>> manages to trigger an selinux deny rule which is audited, then
>>>>>>> the loginuid must make sense on the host. Now presumably it
>>>>>>> will get translated to the mapped host uid, and we can figure
>>>>>>> out the host uid owning it through /etc/subuid. But that adds
>>>>>>> /etc/subuid as a new part of the TCB without any warning <shrug>
>>>>>>> So in that sense, for LSPP, it breaks it.
>>>>>>>
>>>>>>
>>>>>> Looks like my opinion is incorrect.
>>>>>>
>>>>>> In the audit-next tree, Eric added a new audit feature to allow privileged
>>>>>> user to disable AUDIT_LOGINUID_IMMUTABLE. after AUDIT_LOGINUID_IMMUTABLE
>>>>>> is disabled, the privileged user can reset/set the loginuid of task. I
>>>>>> think this way is safe since only privileged user can do the change.
>>>>>>
>>>>>> So I will not change the loginuid part.
>>>>>>
>>>>>> Thanks for your information Serge :)
>>>>>
>>>>> Unfortunately this makes the patchset much less compelling :) The
>>>>> problem I was looking into is that a container running in a user
>>>>> namespace cannot (bc he has ns_capable(CAP_AUDIT_*) but not
>>>>> capable(CAP_AUDIT_*)) set loginuids at all.
>>>>>
>>>>> Which from an LSPP pov is correct; which is why I was hoping you were
>>>>> going to have the audit namespaces be hierarchical, with a task in a
>>>>> level 2 audit ns having two loginuids - one in his own auditns, and
>>>>> one in the initial one.
>>>>
>>>> Right now user namespace + audit is just total crud. We all know
>>>> this... (I'm not sure pid is must better, but I digress) All thoughts
>>>> around loginuid in the kernel right this very moment only make sense in
>>>> the initial user namespace and all permission checks are in the initial
>>>> user namespace as well.
>>>>
>>>> I think I'm a proponent of the hierarchical approach to audit
>>>> namespaces. An audit namespace would hold a reference to the
>>>> pid/user/whatever namespace it was created in/with. Each audit
>>>> namespace should have it's own set of filter rules, etc. Instead of
>>>> just storing 'loginuid' we store 'loginuid+user namespace'. When the
>>>
>>> So long as the kernel stores the kuid_t (which the only sane thing to
>>> do) that is a non-issue.
>>>
>>>> kernel creates a record it should translate the loginuid to the
>>>> namespace of the audit namespace and send the record.
>>>
>>> Yup, that should go without saying. Use kuid_t in kernel and translate
>>> at the kernel-user boundary.
>>>
>>
>> I can implement audit namespace as a hierarchy, give per auditns a level value
>> and a pointer which point to parent auditns.
>>
>> but for the loginuid part, I think we can implement it after we push the audit
>> ns into the upstream.
>>
>> Is this ok?
>
> Well as I"ve said the loginuid part is the only one that interests
> me. I'll be out most of the rest of the year, but I'll review any
> patchset you send for what seems to me to be correctness :)
>

Thanks for your help!
As soon as the frame of auditns being accepted, I think it's easily
to push the loginuid part. :)