[Bug 1424795] Re: Old libselinux in Precise breaks things in Docker on SELinux-enabled host

[Ben Webb]

Same problem here (in my case the host is an x86_64 Fedora 22 box and
the Docker container is running Precise); note that *anything* that
tries to update SELinux context will fail due to the Docker-unaware
libselinux. This includes a simple "cp -a". Since "cp -a" appears to be
used somewhere deep inside dh_install, this breaks package building in a
Precise Docker container. Since that's what I use my Docker containers
for, this is something of a deal breaker for me!

Looks like the specific patch mentioned above is
libselinux-2.0.94_enabled.patch from
http://vault.centos.org/6.6/centosplus/Source/SPackages/libselinux-2.0.94-5.3.0.1.el6.centos.plus.src.rpm
and something like that patch should probably work its way into the
Precise package. (I tried to build a package with the patch to test this
for myself but dh_install failed, see above ;)

My temporary workaround in the meantime was to simply replace the
Precise libselinux1 package with that from Trusty. Frankly I'm surprised
that worked but it does appear to be binary compatible. i.e. my Precise
Dockerfile includes the line

RUN wget
http://mirrors.kernel.org/ubuntu/pool/main/libs/libselinux/libselinux1_2.2.2-1_amd64.deb
&& dpkg -i libselinux1_2.2.2-1_amd64.deb && rm -f
libselinux1_2.2.2-1_amd64.deb

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https://bugs.launchpad.net/bugs/1424795

Title:
  Old libselinux in Precise breaks things in Docker on SELinux-enabled
  host

Status in libselinux package in Ubuntu:
  Confirmed

Bug description:
  In a Docker container running on an SELinux capable kernel, the fact
  that /sys is mounted RO is supposed to signal to the container that
  SELinux is not supported on the inside, so it doesn't try to do things
  that won't work. The version of libselinux in Ubuntu 12.04 is too old
  to have the above check, breaking basic functionality like shadow-
  utils.

  RHEL 6 had the same problem; their fix was to update libselinux:
  https://bugzilla.redhat.com/show_bug.cgi?id=1112748

  Previously reported downstream: https://github.com/tianon/docker-brew-
  ubuntu-core/issues/29

  Release: Ubuntu 12.04.5 LTS

  Installed package version: 2.1.0-4.1ubuntu1

  Expected results:
  # useradd test
  <success>
  # id -Z
  id: --context (-Z) works only on an SELinux-enabled kernel

  Actual results:
  root at b55e77ab9ef4:/# useradd test
  useradd: failure while writing changes to /etc/passwd
  root at b55e77ab9ef4:/# vipw
  vipw: setfscreatecon () failed: Permission denied
  vipw: /etc/passwd is unchanged
  root at b55e77ab9ef4:/# id -Z
  system_u:system_r:svirt_lxc_net_t:s0:c14,c127

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