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 753ff83a50)
Conflicts:
src/network/bridge_driver.c
* needed to change virReportError() to the older
networkReportError()
tests/networkxml2argvdata/nat-network-dns-txt-record.argv
* this test file has an example of an arg with embedded space,
which gets sorrounded by '' in newer releases. Other
items on the same line had been modified.
tests/networkxml2argvdata/routed-network.argv
* in the newer releases, this test file had an --addn-hosts
arg that didn't exist on this branch. Again, it was in the
surrounding context of the changes that had been made on
master.
This patch removed the "--filterwin2k" dnsmasq command line
parameter which was unnecessary for domain specification,
possibly blocked some usage, and was command line clutter.
Gene Czarcinski <gene@czarc.net>
(cherry picked from commit f20b7dbe63)
Conflicts:
tests/networkxml2argvdata/nat-network-dns-txt-record.argv
dnsmasq is forwarding a number of queries upstream that should not
be done. There still remains an MX query for a plain name with no
domain specified that will be forwarded is dnsmasq has --domain=xxx
--local=/xxx/ specified. This does not happen with no domain name
and --local=// ... not a libvirt problem.
BTW, thanks again to Claudio Bley!
(cherry picked from commit f3868259ca)
Conflicts:
AUTHORS
The path to the dnsmasq binary can be configured while in the test data
the path is hard-coded to /usr/bin/. This break the test suite if a the
binary is located in a different location, like /usr/local/sbin/.
Replace the hard coded path in the test data by a token, which is
dynamically replaced in networkxml2argvtest with the configured path
after the test data has been loaded.
(Another option would have been to modify configure.ac to generate the
test data during configure, but I do not know of an easy way do trick
configure into mass-generate those test files without listing every
single one, which I consider less flexible.)
- unit-test the unit-test:
#include <assert.h>
#define TEST(in,token,rep,out) { char *buf = strdup(in); assert(!replaceTokens(&buf, token, rep) && !strcmp(buf, out)); free(buf); }
TEST("", "AA", "B", "");
TEST("A", "AA", "B", "A");
TEST("AA", "AA", "B", "B");
TEST("AAA", "AA", "B", "BA");
TEST("AA", "AA", "BB", "BB");
TEST("AA", "AA", "BBB", "BBB");
TEST("<AA", "AA", "B", "<B");
TEST("<AA", "AA", "BB", "<BB");
TEST("<AA", "AA", "BBB", "<BBB");
TEST("AA>", "AA", "B", "B>");
TEST("AA>", "AA", "BB", "BB>");
TEST("AA>", "AA", "BBB", "BBB>");
TEST("<AA>", "AA", "B", "<B>");
TEST("<AA>", "AA", "BB", "<BB>");
TEST("<AA>", "AA", "BBB", "<BBB>");
TEST("<AA|AA>", "AA", "B", "<B|B>");
TEST("<AA|AA>", "AA", "BB", "<BB|BB>");
TEST("<AA|AA>", "AA", "BBB", "<BBB|BBB>");
TEST("<AAAA>", "AA", "B", "<BB>");
TEST("<AAAA>", "AA", "BB", "<BBBB>");
TEST("<AAAA>", "AA", "BBB", "<BBBBBB>");
TEST("AAAA>", "AA", "B", "BB>");
TEST("AAAA>", "AA", "BB", "BBBB>");
TEST("AAAA>", "AA", "BBB", "BBBBBB>");
TEST("<AAAA", "AA", "B", "<BB");
TEST("<AAAA", "AA", "BB", "<BBBB");
TEST("<AAAA", "AA", "BBB", "<BBBBBB");
alarm(1); /* no infinite loop */
TEST("A", "A", "A", "A");
TEST("AA", "A", "A", "AA");
alarm(0);
Signed-off-by: Philipp Hahn <hahn@univention.de>
Hi,
this is the fifth version of my SRV record for DNSMasq patch rebased
for the current codebase to the bridge driver and libvirt XML file to
include support for the SRV records in the DNS. The syntax is based on
DNSMasq man page and tests for both xml2xml and xml2argv were added as
well. There are some things written a better way in comparison with
version 4, mainly there's no hack in tests/networkxml2argvtest.c and
also the xPath context is changed to use a simpler query using the
virXPathInt() function relative to the current node.
Also, the patch is also fixing the networkxml2argv test to pass both
checks, i.e. both unit tests and also syntax check.
Please review,
Michal
Signed-off-by: Michal Novotny <minovotn@redhat.com>
