[lxc-devel] Howto user namespaces?

[Eric W. Biederman]

Serge Hallyn <serge.hallyn at ubuntu.com> writes:

> Quoting Eric W. Biederman (ebiederm at xmission.com):
>> 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.
>
> After creating the /dev/ttyN we chown them to the root uid inside the
> container.  I've not had failures with this.

Yes that should work fine.

There aren't any chown calls in Richards strace logs, why that is I
don't know, but that seems to be cause of his troubles.

Eric