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Re: [PATCH 0/3] Enable namespaced file capabilities

From "Serge E. Hallyn" <serge@hallyn.com>
Newsgroups linux.kernel
Subject Re: [PATCH 0/3] Enable namespaced file capabilities
Date 2017-06-23 20:40 +0200
Message-ID <tVBET-5G1-35@gated-at.bofh.it> (permalink)
References <tVfEl-nS-3@gated-at.bofh.it> <tVqT8-7uy-5@gated-at.bofh.it> <tVzjI-4mL-21@gated-at.bofh.it> <tVztn-4pX-7@gated-at.bofh.it> <tVBbP-5wk-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Quoting Stefan Berger (stefanb@linux.vnet.ibm.com):
> On 06/23/2017 12:16 PM, Casey Schaufler wrote:
> >On 6/23/2017 9:00 AM, Serge E. Hallyn wrote:
> >>Quoting Amir Goldstein (amir73il@gmail.com):
> >>>On Thu, Jun 22, 2017 at 9:59 PM, Stefan Berger
> >>><stefanb@linux.vnet.ibm.com> wrote:
> >>>>This series of patches primary goal is to enable file capabilities
> >>>>in user namespaces without affecting the file capabilities that are
> >>>>effective on the host. This is to prevent that any unprivileged user
> >>>>on the host maps his own uid to root in a private namespace, writes
> >>>>the xattr, and executes the file with privilege on the host.
> >>>>
> >>>>We achieve this goal by writing extended attributes with a different
> >>>>name when a user namespace is used. If for example the root user
> >>>>in a user namespace writes the security.capability xattr, the name
> >>>>of the xattr that is actually written is encoded as
> >>>>security.capability@uid=1000 for root mapped to uid 1000 on the host.
> >>>>When listing the xattrs on the host, the existing security.capability
> >>>>as well as the security.capability@uid=1000 will be shown. Inside the
> >>>>namespace only 'security.capability', with the value of
> >>>>security.capability@uid=1000, is visible.
> >>>>
> >>>Am I the only one who thinks that suffix is perhaps not the best grammar
> >>>to use for this namespace?
> >>You're the only one to have mentioned it so far.
> >>
> >>>xattrs are clearly namespaced by prefix, so it seems right to me to keep
> >>>it that way - define a new special xattr namespace "ns" and only if that
> >>>prefix exists, the @uid suffix will be parsed.
> >>>This could be either  ns.security.capability@uid=1000 or
> >>>ns@uid=1000.security.capability. The latter seems more correct to me,
> >>>because then we will be able to namespace any xattr without having to
> >>>protect from "unprivileged xattr injection", i.e.:
> >>>setfattr -n "user.whatever.foo@uid=0"
> >>I like it for simplifying the parser code.  One concern I have is that,
> >>since ns.* is currently not gated, one could write ns.* on an older
> >>kernel and then exploit it on a newer one.
> >security.ns.capability@uid=1000, then?
> 
> Imo, '.ns' is redundant and 'encoded' in the '@'.

So how about
	security.@uid=1000@@capability ?

Maybe it's not worth it.

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Thread

[PATCH 0/3] Enable namespaced file capabilities Stefan Berger <stefanb@linux.vnet.ibm.com> - 2017-06-22 21:10 +0200
  [PATCH 1/3] xattr: Enable security.capability in user namespaces Stefan Berger <stefanb@linux.vnet.ibm.com> - 2017-06-22 21:10 +0200
    [PATCH] xattr: fix kstrdup.cocci warnings kbuild test robot <lkp@intel.com> - 2017-06-24 23:10 +0200
    Re: [PATCH 1/3] xattr: Enable security.capability in user namespaces kbuild test robot <lkp@intel.com> - 2017-06-24 23:10 +0200
  Re: [PATCH 0/3] Enable namespaced file capabilities Casey Schaufler <casey@schaufler-ca.com> - 2017-06-22 22:00 +0200
    Re: [PATCH 0/3] Enable namespaced file capabilities Stefan Berger <stefanb@linux.vnet.ibm.com> - 2017-06-22 22:20 +0200
      Re: [PATCH 0/3] Enable namespaced file capabilities Casey Schaufler <casey@schaufler-ca.com> - 2017-06-22 22:40 +0200
        Re: [PATCH 0/3] Enable namespaced file capabilities Stefan Berger <stefanb@linux.vnet.ibm.com> - 2017-06-22 23:10 +0200
        Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-22 23:10 +0200
          Re: [PATCH 0/3] Enable namespaced file capabilities Casey Schaufler <casey@schaufler-ca.com> - 2017-06-23 00:50 +0200
            Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 01:10 +0200
  Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 01:40 +0200
    Re: [PATCH 0/3] Enable namespaced file capabilities James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-06-23 02:20 +0200
      Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 03:30 +0200
      Re: [PATCH 0/3] Enable namespaced file capabilities ebiederm@xmission.com (Eric W. Biederman) - 2017-06-23 19:50 +0200
        Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 20:40 +0200
  Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 01:40 +0200
  Re: [PATCH 0/3] Enable namespaced file capabilities James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-06-23 01:40 +0200
  Re: [PATCH 0/3] Enable namespaced file capabilities Amir Goldstein <amir73il@gmail.com> - 2017-06-23 09:10 +0200
    Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 18:10 +0200
      Re: [PATCH 0/3] Enable namespaced file capabilities Casey Schaufler <casey@schaufler-ca.com> - 2017-06-23 18:20 +0200
        Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 18:40 +0200
          Re: [PATCH 0/3] Enable namespaced file capabilities Casey Schaufler <casey@schaufler-ca.com> - 2017-06-23 19:00 +0200
            Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 19:10 +0200
              Re: [PATCH 0/3] Enable namespaced file capabilities ebiederm@xmission.com (Eric W. Biederman) - 2017-06-23 20:00 +0200
                Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 20:40 +0200
          Re: [PATCH 0/3] Enable namespaced file capabilities James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-06-23 19:10 +0200
            Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 19:30 +0200
            Re: [PATCH 0/3] Enable namespaced file capabilities Stefan Berger <stefanb@linux.vnet.ibm.com> - 2017-06-23 19:40 +0200
              Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 20:40 +0200
        Re: [PATCH 0/3] Enable namespaced file capabilities Stefan Berger <stefanb@linux.vnet.ibm.com> - 2017-06-23 20:10 +0200
          Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 20:40 +0200
            Re: [PATCH 0/3] Enable namespaced file capabilities Casey Schaufler <casey@schaufler-ca.com> - 2017-06-23 22:40 +0200
            Re: [PATCH 0/3] Enable namespaced file capabilities Stefan Berger <stefanb@linux.vnet.ibm.com> - 2017-06-24 01:10 +0200
              Re: [PATCH 0/3] Enable namespaced file capabilities Casey Schaufler <casey@schaufler-ca.com> - 2017-06-24 02:00 +0200
    Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-28 07:50 +0200
      Re: [PATCH 0/3] Enable namespaced file capabilities Amir Goldstein <amir73il@gmail.com> - 2017-06-28 09:20 +0200
        Re: [PATCH 0/3] Enable namespaced file capabilities Stefan Berger <stefanb@linux.vnet.ibm.com> - 2017-06-28 16:10 +0200
        Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-28 16:30 +0200
  Re: [PATCH 0/3] Enable namespaced file capabilities Vivek Goyal <vgoyal@redhat.com> - 2017-06-23 22:20 +0200
    Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 22:20 +0200
      Re: [PATCH 0/3] Enable namespaced file capabilities Vivek Goyal <vgoyal@redhat.com> - 2017-06-23 22:40 +0200
        Re: [PATCH 0/3] Enable namespaced file capabilities "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-23 23:00 +0200

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