(RHSA-2015:0623) Low: docker security, bug fix, and enhancement update

Docker is a service providing container management on Linux.

It was found that a malicious container image could overwrite arbitrary portions
of the host file system by including absolute symlinks, potentially leading to
privilege escalation. (CVE-2014-9356)

A flaw was found in the way the Docker service unpacked images or builds after a
“docker pull”. An attacker could use this flaw to provide a malicious image or
build that, when unpacked, would escalate their privileges on the system.
(CVE-2014-9357)

Red Hat would like to thank Docker Inc. for reporting these issues.

The docker-python subpackage provides the new Atomic tool. The goal of Atomic is
to provide a high level, coherent entry point for Red Hat Enterprise Linux
Atomic Host. Atomic makes it easier to interact with special kinds of
containers, such as super-privileged debugging tools. Comprehensive information
and documentation is available in the atomic manual pages.

The docker packages have been upgraded to upstream version 1.4.1, which provides
a number of bug fixes and enhancements over the previous version, most notably
an experimental overlayfs storage driver. (BZ#1174351)

Bug fixes:

• The JSON configuration files for containers and images were inconsistent. As a
  consequence, when these files were parsed by the “docker inspect” command, the
  output was unnecessarily complex. This update improves the key naming schema in
  the configuration files and the output from “docker inspect” is now uniform.
  (BZ#1092773)

• The /run directory had an incorrect SELinux label. As a consequence,
  containers could not access /run. This update corrects the SELinux label and
  containers now have access to /run. (BZ#1100009)

• The Docker service contained an incorrect path for the secrets directory. As a
  consequence, executing “docker run” failed to create containers. This update
  fixes the default path to the secrets directory and “docker run” now executes
  successfully. (BZ#1102568)

• It was not possible to specify a default repository in the configuration file
  in cases where all docker.io files are inaccessible. As a consequence, running
  docker commands failed because they could not contact the default repositories.
  Now, it is possible to specify a local Docker repository, and commands no longer
  fail because they are able to connect to a local private repository.
  (BZ#1106430)

• When executing the “docker attach” command on a container which was in the
  process of shutting down, the process did not fail, but became unresponsive.
  This bug has been fixed, and running “docker attach” on a container which is
  shutting down causes the attach process to fail with an informative error
  message that it is not possible to attach to a stopped container. (BZ#1113608)

• The “docker run” sub-command incorrectly returned non-zero exit codes, when
  they all should have been zero. As a consequence, it was not possible to
  differentiate between the exit codes of the docker command line and exit codes
  of contained processes, which in turn made automated control of “docker run”
  impossible. This update fixes the inconsistencies within the exit codes of
  “docker run”. Additionally, this update also fixes inconsistencies of other
  docker sub-commands and improves the language in the error and warning messages.
  (BZ#1162807)

• Adding a new registry with the “–registry-prepend” option did not follow the
  correct order to query and download an image. As a consequence, it did not query
  the prepended new registry first, but rather started with querying docker.io.
  The “–registry-prepend” option has been renamed to “–registry-add” and its
  behavior has been changed to query the registries added in the given order, with
  docker.io queried last. (BZ#1186153)

All docker users are advised to upgrade to these updated packages, which correct
these issues and add these enhancements.