Re: [RFC 1/1] shiftfs: uid/gid shifting bind mount

[Eric W. Biederman]

Djalal Harouni <tixxdz@xxxxxxxxx> writes:

> On Mon, Feb 13, 2017 at 11:15 AM, Eric W. Biederman
> <ebiederm@xxxxxxxxxxxx> wrote:
>> James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> writes:

>>> So is this.  Basically anything that begins by mounting gets a super
>>> block and can use the s_user_ns to map from the filesystem view to the
>>> kernel view of ids.  Apart from greater sophistication in the
>>> parametrisation, it sounds like we have all the machinery you need.
>>>  I'm sure the containers people will consider reasonable patches to
>>> change this.
>>
>> Yes.
>>
>> And to be clear we have all of that merged now and mostly present and
>> hooked up in all filesystems without any shiftfs like changes needed.
>>
>> To use this with a filesystem a last pass needs to be had to verify that
>> the cases where something does not map are handled cleanly.
>
> Still this does not answer the question how to dynamically
> *attach/share* data or read-only volumes as defined by
> orchestration/container tools into several containers. Am I missing
> something or is the plan to have per superblock mount for each one ?

Agreed.  That is a related problem and the problem that shiftfs
is working to solve.

If you only need a single mapping the infrastructure is basically done
in the kernel today.  If you need multiple mappings we need something
more.

Eric