[PATCH 0/5 RFC] Add an interface to discover relationships between namespaces

From	Andrey Vagin <avagin@openvz.org>
Newsgroups	linux.kernel
Subject	[PATCH 0/5 RFC] Add an interface to discover relationships between namespaces
Date	2016-07-14 20:30 +0200
Message-ID	<rUTyx-4Je-5@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Each namespace has an owning user namespace and now there is not way
to discover these relationships.

Pid and user namepaces are hierarchical. There is no way to discover
parent-child relationships too.

Why we may want to know relationships between namespaces?

One use would be visualization, in order to understand the running system.
Another would be to answer the question: what capability does process X have to
perform operations on a resource governed by namespace Y?

One more use-case (which usually called abnormal) is checkpoint/restart.
In CRIU we age going to dump and restore nested namespaces.

There [1] was a discussion about which interface to choose to determing
relationships between namespaces.

Eric suggested to add two ioctl-s [2]:
> Grumble, Grumble.  I think this may actually a case for creating ioctls
> for these two cases.  Now that random nsfs file descriptors are bind
> mountable the original reason for using proc files is not as pressing.
>
> One ioctl for the user namespace that owns a file descriptor.
> One ioctl for the parent namespace of a namespace file descriptor.

Here is an implementaions of these ioctl-s.

[1] https://lkml.org/lkml/2016/7/6/158
[2] https://lkml.org/lkml/2016/7/9/101

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: "W. Trevor King" <wking@tremily.us>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Serge Hallyn <serge.hallyn@canonical.com>

--
2.5.5

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[PATCH 0/5 RFC] Add an interface to discover relationships between namespaces Andrey Vagin <avagin@openvz.org> - 2016-07-14 20:30 +0200
  [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace Andrey Vagin <avagin@openvz.org> - 2016-07-14 20:30 +0200
    Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace  for a namespace "W. Trevor King" <wking@tremily.us> - 2016-07-14 21:10 +0200
  Re: [PATCH 0/5 RFC] Add an interface to discover relationships  between namespaces Andrey Vagin <avagin@openvz.org> - 2016-07-15 00:10 +0200
    [PATCH 5/5] tools/testing: add a test to check nsfs ioctl-s Andrey Vagin <avagin@openvz.org> - 2016-07-15 04:20 +0200
    [PATCH 4/5] nsfs: add ioctl to get a parent namespace Andrey Vagin <avagin@openvz.org> - 2016-07-15 04:20 +0200
      Re: [PATCH 4/5] nsfs: add ioctl to get a parent namespace ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 07:30 +0200
    [PATCH 3/5] nsfs: add ioctl to get an owning user namespace for ns file descriptor Andrey Vagin <avagin@openvz.org> - 2016-07-15 04:20 +0200
    [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace Andrey Vagin <avagin@openvz.org> - 2016-07-15 04:20 +0200
      Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 07:20 +0200
        Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 16:50 +0200
          Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace  for a namespace "W. Trevor King" <wking@tremily.us> - 2016-07-24 19:10 +0200
      Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace  for a namespace "W. Trevor King" <wking@tremily.us> - 2016-07-24 19:00 +0200
    Re: [PATCH 1/5] namespaces: move user_ns into ns_common ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 07:20 +0200
    Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 07:30 +0200
  Re: [PATCH 0/5 RFC] Add an interface to discover relationships  between namespaces "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-07-21 16:50 +0200
    Re: [PATCH 0/5 RFC] Add an interface to discover relationships  between namespaces Andrey Vagin <avagin@openvz.org> - 2016-07-22 20:30 +0200
      Re: [PATCH 0/5 RFC] Add an interface to discover relationships  between namespaces "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-07-25 13:50 +0200
        Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-25 15:40 +0200
          Re: [PATCH 0/5 RFC] Add an interface to discover relationships  between namespaces "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-07-25 16:50 +0200
            Re: [PATCH 0/5 RFC] Add an interface to discover relationships  between namespaces "Serge E. Hallyn" <serge@hallyn.com> - 2016-07-25 17:00 +0200
              Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-25 17:40 +0200
            Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-25 17:20 +0200
  Re: [PATCH 0/5 RFC] Add an interface to discover relationships  between namespaces "W. Trevor King" <wking@tremily.us> - 2016-07-23 23:20 +0200
    Re: [PATCH 0/5 RFC] Add an interface to discover relationships  between namespaces James Bottomley <James.Bottomley@HansenPartnership.com> - 2016-07-23 23:40 +0200
      Re: [PATCH 0/5 RFC] Add an interface to discover relationships  between namespaces "W. Trevor King" <wking@tremily.us> - 2016-07-24 00:10 +0200
        Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 00:20 +0200
          Re: [PATCH 0/5 RFC] Add an interface to discover relationships  between namespaces "W. Trevor King" <wking@tremily.us> - 2016-07-24 00:40 +0200
            Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 07:10 +0200

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