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

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Message-ID: <20131210165152.GA6028@sergelap>
Date:	Tue, 10 Dec 2013 10:51:52 -0600
From:	Serge Hallyn <serge.hallyn@...ntu.com>
To:	Gao feng <gaofeng@...fujitsu.com>
Cc:	Richard Guy Briggs <rgb@...hat.com>,
	containers@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org, eparis@...hat.com,
	linux-audit@...hat.com, ebiederm@...ssion.com, sgrubb@...hat.com
Subject: Re: [RFC Part1 PATCH 00/20 v2] Add namespace support for audit

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.

-serge
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