On Tue, Nov 4, 2014 at 5:57 AM, Tejun Heo [off-list ref] wrote:

Hello, Aditya.

On Mon, Nov 03, 2014 at 03:12:28PM -0800, Aditya Kali wrote:

quoted

I think the sane-behavior flag is only temporary and will be removed
anyways, right? So I didn't bother asking user to supply it. But I can
make the change as you suggested. We just have to make sure that tasks
inside cgroupns cannot mount non-default hierarchies as it would be a
regression.

I'm not sure whether supporting mounting from inside a ns is even
necessary but, if it is, can't you just test against cgrp_dfl_root?
There's no reason to do anything differnetly for ns mounting.

I am not sure I fully understand what you mean. But we don't have a
way to test against cgrp_dfl_root while parsing mount-options. They
only way we know that user is trying to mount a default hierarchy is
via the sane_behavior flag. So I need to test against this flag it if
we want to restrict processes inside cgroupns to mounting the default
hierarchy only.
Or are you suggesting that its OK for nsown_capable(CAP_SYS_ADMIN)
processes to mount any cgroup hierarchy (irrespective of their
cgroupns)? I assumed that this will be a undesirable.

Thanks.

--
tejun

Thanks,
-- 
Aditya