Re: Detecting if you are running in a container

["Serge E. Hallyn" <serge@hallyn.com>]

Quoting david@lang.hm (david@lang.hm):
> On Tue, 11 Oct 2011, Eric W. Biederman wrote:
> 
> >david@lang.hm writes:
> >
> >>On Tue, 11 Oct 2011, Eric W. Biederman wrote:
> >>
> >>>Theodore Tso <tytso@MIT.EDU> writes:
> >>>
> >>>>On Oct 11, 2011, at 2:42 AM, Eric W. Biederman wrote:
> >>>>
> >>>I admit for a lot of test cases that it makes sense not to use a full
> >>>set of userspace daemons.  At the same time there is not particularly
> >>>good reason to have a design that doesn't allow you to run a full
> >>>userspace.
> >>
> >>how do you share the display between all the different containers if they are
> >>trying to run the X server?
> >
> >Either X does not start because the hardware it needs is not present or
> >Xnest or similar gets started.
> >
> >>how do you avoid all the containers binding to the same port on the default IP
> >>address?
> >
> >Network namespaces.
> >
> >>how do you arbitrate dbus across the containers.
> >
> >Why should you?
> 
> because the containers are simulating different machines, and dbus
> doesn't work arcross different machines.

Exactly - Eric is saying dbus should not be (and is not) shared among
containers.

> >>when a new USB device gets plugged in, which container gets control of
> >>it?
> >
> >None of them.  Although today they may all get the uevent.  None of the
> >containers should have permission to call mknod to mess with it.
> 
> why would the software inside a container not have the rights to do
> a mknod inside the container?

Why shouldn't an unprivileged user be allowed to mknod on the host?

-serge