Message-ID: <52AE75D7.4020604@cn.fujitsu.com>
Date:	Mon, 16 Dec 2013 11:39:03 +0800
From:	Gao feng <gaofeng@...fujitsu.com>
To:	"Serge E. Hallyn" <serge@...lyn.com>,
	Eric Paris <eparis@...hat.com>
CC:	Richard Guy Briggs <rgb@...hat.com>,
	containers@...ts.linux-foundation.org,
	Serge Hallyn <serge.hallyn@...ntu.com>,
	linux-kernel@...r.kernel.org, linux-audit@...hat.com,
	ebiederm@...ssion.com
Subject: Re: [RFC Part1 PATCH 00/20 v2] Add namespace support for audit

On 12/11/2013 04:36 AM, Serge E. Hallyn wrote:
> Quoting Eric Paris (eparis@...hat.com):
>> On Tue, 2013-12-10 at 10:51 -0600, Serge Hallyn wrote:
>>> Quoting Gao feng (gaofeng@...fujitsu.com):
>>>> On 12/10/2013 02:26 AM, Serge Hallyn wrote:
>>>>> Quoting Gao feng (gaofeng@...fujitsu.com):
>>>>>> On 12/07/2013 06:12 AM, Serge E. Hallyn wrote:
>>>>>>> Quoting Gao feng (gaofeng@...fujitsu.com):
>>>>>>>> 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?
>> It's a pretty major rewrite, but at least it makes sense.  Things like
>> AVC's might show up in multiple audit logs, but in every log they would
>> make sense to the admin of that namespace...
>>
>> But what the hell do I know...
> 
> Exactly how it would all affect selinux.  I'm happy it seems we agree.

This idea looks good to me, I will Investigate this. :)

Thanks.
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