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Libvirt provides a portable, long term stable C API for managing the
virtualization technologies provided by many operating systems. It
includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware
vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER
Hypervisor.
2abde0ac07
This bug resolves CVE-2012-3411, which is described in the following
bugzilla report:
https://bugzilla.redhat.com/show_bug.cgi?id=833033
The following report is specifically for libvirt on Fedora:
https://bugzilla.redhat.com/show_bug.cgi?id=874702
In short, a dnsmasq instance run with the intention of listening for
DHCP/DNS requests only on a libvirt virtual network (which is
constructed using a Linux host bridge) would also answer queries sent
from outside the virtualization host.
This patch takes advantage of a new dnsmasq option "--bind-dynamic",
which will cause the listening socket to be setup such that it will
only receive those requests that actually come in via the bridge
interface. In order for this behavior to actually occur, not only must
"--bind-interfaces" be replaced with "--bind-dynamic", but also all
"--listen-address" options must be replaced with a single
"--interface" option. Fully:
--bind-interfaces --except-interface lo --listen-address x.x.x.x ...
(with --listen-address possibly repeated) is replaced with:
--bind-dynamic --interface virbrX
Of course libvirt can't use this new option if the host's dnsmasq
doesn't have it, but we still want libvirt to function (because the
great majority of libvirt installations, which only have mode='nat'
networks using RFC1918 private address ranges (e.g. 192.168.122.0/24),
are immune to this vulnerability from anywhere beyond the local subnet
of the host), so we use the new dnsmasqCaps API to check if dnsmasq
supports the new option and, if not, we use the "old" option style
instead. In order to assure that this permissiveness doesn't lead to a
vulnerable system, we do check for non-private addresses in this case,
and refuse to start the network if both a) we are using the old-style
options, and b) the network has a publicly routable IP
address. Hopefully this will provide the proper balance of not being
disruptive to those not practically affected, and making sure that
those who *are* affected get their dnsmasq upgraded.
(--bind-dynamic was added to dnsmasq in upstream commit
54dd393f3938fc0c19088fbd319b95e37d81a2b0, which was included in
dnsmasq-2.63)
(cherry picked from commit
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| daemon | ||
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| examples | ||
| gnulib | ||
| include | ||
| m4 | ||
| po | ||
| python | ||
| src | ||
| tests | ||
| tools | ||
| .dir-locals.el | ||
| .gitignore | ||
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| .mailmap | ||
| AUTHORS | ||
| autobuild.sh | ||
| autogen.sh | ||
| bootstrap | ||
| bootstrap.conf | ||
| cfg.mk | ||
| ChangeLog-old | ||
| configure.ac | ||
| COPYING.LIB | ||
| HACKING | ||
| libvirt.pc.in | ||
| libvirt.spec.in | ||
| Makefile.am | ||
| Makefile.nonreentrant | ||
| mingw32-libvirt.spec.in | ||
| README | ||
| README-hacking | ||
| TODO | ||
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>