[lxc-devel] Howto user namespaces?

[Eric W. Biederman]

richard -rw- weinberger <richard.weinberger at gmail.com> writes:

> On Thu, Apr 11, 2013 at 7:03 AM, Eric W. Biederman
> <ebiederm at xmission.com> wrote:
>> richard -rw- weinberger <richard.weinberger at gmail.com> writes:
>>> {st_mode=S_IFCHR|0644, st_rdev=makedev(5, 1), ...}) = 0
>>> [pid  3100] chmod("/dev/pts/5", 020644) = -1 EPERM (Operation not permitted)
>>
>> I am puzzled why we don't see something to create /dev/pts/5 in this trace.
>
> I have also no idea.
> Please see both attached strace logs (linux v3.9-rc6, lxc 0.9.0).
> One with lxc.autodev = 0, the other with = 1.

I have read through and I can see why you are failing.
With autodev you are failing with mknod /dev/null.
Without autodev you are creating pts (I assume to represent /dev/ttyN)
before creating the user namespace and then there is a permission
problem with chmod.

Both of which seem like correct behavior from the kernels standpoint.

> My lxc config:
> ----
> lxc.network.type = empty
> lxc.rootfs = /var/lib/lxc/test2/rootfs
> lxc.utsname = test2
> lxc.autodev = 0
> lxc.tty = 4

Let me suggest setting lxc.tty = 0. So you don't get tty creation
and see how far that goes.

> lxc.pts = 1024
> lxc.mount = /var/lib/lxc/test2/fstab
> lxc.id_map = u 0 100000 10000
> lxc.id_map = g 0 100000 10000
> ----

Eric