[Devel] call_usermodehelper in containers

[Jeff Layton]

On Mon, 18 Nov 2013 19:02:59 +0100
Oleg Nesterov <oleg at redhat.com> wrote:

> On 11/18, Oleg Nesterov wrote:
> >
> > On 11/15, Eric W. Biederman wrote:
> > >
> > > I don't understand that one.  Having a preforked thread with the proper
> > > environment that can act like kthreadd in terms of spawning user mode
> > > helpers works and is simple.
> >
> > Can't we ask ->child_reaper to create the non-daemonized kernel thread
> > with the "right" ->nsproxy, ->fs, etc?
> >
> > IOW. Please the the "patch" below. It is obviously incomplete and wrong,
> > and it can be more clear/clean. And probably we need another API. Just
> > to explain what I mean.
> 
> Or, perhaps UMH_IN_MY_NS should only work if ->child_reaper explicitly
> does, say, prctl(PR_SPAWN_UMH_IN_NS_HELPER) which forks the non-daemonized
> kernel kthread_worker thread, I dunno.
> 
> Oleg.
> 

Neat idea.

So is it always the case that tasks in a container have the same
namespace settings and capabilities as the child_reaper?

We'll still have the basic problem for nfsd that we'll need to keep
track of what the child_reaper is when nfsd is started, but I think
that's not too hard to solve.

-- 
Jeff Layton <jlayton at redhat.com>