libvirt security update

CentOS Errata and Security Advisory CESA-2015:0008

The libvirt library is a C API for managing and interacting with the
virtualization capabilities of Linux and other operating systems.
In addition, libvirt provides tools for remote management of
virtualized systems.

It was found that when the VIR_DOMAIN_XML_MIGRATABLE flag was used, the
QEMU driver implementation of the virDomainGetXMLDesc() function could
bypass the restrictions of the VIR_DOMAIN_XML_SECURE flag. A remote
attacker able to establish a read-only connection to libvirtd could use
this flaw to leak certain limited information from the domain XML data.
(CVE-2014-7823)

This issue was discovered by Eric Blake of Red Hat.

This update also fixes the following bugs:

• In Red Hat Enterprise Linux 6, libvirt relies on the QEMU emulator to
  supply the error message when an active commit is attempted. However, with
  Red Hat Enterprise Linux 7, QEMU added support for an active commit, but an
  additional interaction from libvirt to fully enable active commits is still
  missing. As a consequence, attempts to perform an active commit caused
  libvirt to become unresponsive. With this update, libvirt has been fixed to
  detect an active commit by itself, and now properly declares the feature as
  unsupported. As a result, libvirt no longer hangs when an active commit is
  attempted and instead produces an error message.

Note that the missing libvirt interaction will be added in Red Hat
Enterprise Linux 7.1, adding full support for active commits. (BZ#1150379)

• Prior to this update, the libvirt API did not properly check whether a
  Discretionary Access Control (DAC) security label is non-NULL before trying
  to parse user/group ownership from it. In addition, the DAC security label
  of a transient domain that had just finished migrating to another host is
  in some cases NULL. As a consequence, when the virDomainGetBlockInfo API
  was called on such a domain, the libvirtd daemon sometimes terminated
  unexpectedly. With this update, libvirt properly checks DAC labels before
  trying to parse them, and libvirtd thus no longer crashes in the described
  scenario. (BZ#1171124)

• If a block copy operation was attempted while another block copy was
  already in progress to an explicit raw destination, libvirt previously
  stopped regarding the destination as raw. As a consequence, if the
  qemu.conf file was edited to allow file format probing, triggering the bug
  could allow a malicious guest to bypass sVirt protection by making libvirt
  regard the file as non-raw. With this update, libvirt has been fixed to
  consistently remember when a block copy destination is raw, and guests can
  no longer circumvent sVirt protection when the host is configured to allow
  format probing. (BZ#1149078)

All libvirt users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues. After installing the
updated packages, libvirtd will be restarted automatically.

Merged security bulletin from advisories:
https://lists.centos.org/pipermail/centos-announce/2015-January/083021.html

Affected packages:
libvirt
libvirt-client
libvirt-daemon
libvirt-daemon-config-network
libvirt-daemon-config-nwfilter
libvirt-daemon-driver-interface
libvirt-daemon-driver-lxc
libvirt-daemon-driver-network
libvirt-daemon-driver-nodedev
libvirt-daemon-driver-nwfilter
libvirt-daemon-driver-qemu
libvirt-daemon-driver-secret
libvirt-daemon-driver-storage
libvirt-daemon-kvm
libvirt-daemon-lxc
libvirt-devel
libvirt-docs
libvirt-lock-sanlock
libvirt-login-shell
libvirt-python

Upstream details at:
https://access.redhat.com/errata/RHSA-2015:0008