This patch changes how parameters are passed to dnsmasq.  Instead of
being on the command line, the parameters are put into a file (one
parameter per line) and a commandline --conf-file= specifies the
location of the file.  The file is located in the same directory as
the leases file.

Putting the dnsmasq parameters into a configuration file
allows them to be examined and more easily understood than
examining the command lines displayed by "ps ax".  This is
especially true when a number of networks have been started.

When the use of dnsmasq was originally done, the required command line
was simple, but it has gotten more complicated over time and will
likely become even more complicated in the future.

Note: The test conf files have all been renamed .conf instead of
.argv, and tests/networkxml2xmlargvdata was moved to
tests/networkxml2xmlconfdata.

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)

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: NMichal Novotny <minovotn@redhat.com>

The network XML is updated in the following ways:

1) The <forward> element can now contain a list of forward interfaces:

     <forward .... >
       <interface dev='eth10'/>
       <interface dev='eth11'/>
       <interface dev='eth12'/>
       <interface dev='eth13'/>
     </forward>

   The first of these takes the place of the dev attribute that is
   normally in <forward> - when defining a network you can specify
   either one, and on output both will be present. If you specify
   both on input, they must match.

2) In addition to forward modes of 'nat' and 'route', these new modes
   are supported:

     private, passthrough, vepa - when this network is referenced by a
     domain's interface, it will have the same effect as if the
     interface had been defined as type='direct', e.g.:

        <interface type='direct'>
          <source mode='${mode}' dev='${dev}>
          ...
        </interface>

     where ${mode} is one of the three new modes, and ${dev} is an interface
     selected from the list given in <forward>.

     bridge - if a <forward> dev (or multiple devs) is defined, and
     forward mode is 'bridge' this is just like the modes 'private',
     'passthrough', and 'vepa' above. If there is no forward dev
     specified but a bridge name is given (e.g. "<bridge
     name='br0'/>"), then guest interfaces using this network will use
     libvirt's "host bridge" mode, equivalent to this:

       <interface type='bridge'>
          <source bridge='${bridge-name}'/>
          ...
       </interface>

3) A network can have multiple <portgroup> elements, which may be
   selected by the guest interface definition (by adding
   "portgroup='${name}'" in the <source> element along with the
   network name). Currently a portgroup can only contain a
   virtportprofile, but the intent is that other configuration items
   may be put there int the future (e.g. bandwidth config). When
   building a guest's interface, if the <interface> XML itself has no
   virtportprofile, and if the requested network has a portgroup with
   a name matching the name given in the <interface> (or if one of the
   network's portgroups is marked with the "default='yes'" attribute),
   the virtportprofile from that portgroup will be used by the
   interface.

4) A network can have a virtportprofile defined at the top level,
   which will be used by a guest interface when connecting in one of
   the 'direct' modes if the guest interface XML itself hasn't
   specified any virtportprofile, and if there are also no matching
   portgroups on the network.

This commit introduces the <dns> element and <txt> record for the
virtual DNS network. The DNS TXT record can be defined using following
syntax in the network XML file:

  <dns>
    <txt name="example" value="example value" />
  </dns>

Also, the Relax-NG scheme has been altered to allow the texts without
spaces only for the name element and some nitpicks about memory
free'ing have been fixed by Laine so therefore I'm adding Laine to the
SOB clause ;-)
Signed-off-by: NMichal Novotny <minovotn@redhat.com>
Signed-off-by: NLaine Stump <laine@laine.org>

This commit adds support for IPv6 parsing and formatting to the
virtual network XML parser, including moving around data definitions
to allow for multiple <ip> elements on a single network, but only
changes the consumers of this API to accommodate for the changes in
API/structure, not to add any actual IPv6 functionality. That will
come in a later patch - this patch attempts to maintain the same final
functionality in both drivers that use the network XML parser - vbox
and "bridge" (the Linux bridge-based driver used by the qemu
hypervisor driver).

* src/libvirt_private.syms: Add new private API functions.
* src/conf/network_conf.[ch]: Change C data structure and
  parsing/formatting.
* src/network/bridge_driver.c: Update to use new parser/formatter.
* src/vbox/vbox_tmpl.c: update to use new parser/formatter
* docs/schemas/network.rng: changes to the schema -
  * there can now be more than one <ip> element.
  * ip address is now an ip-addr (ipv4 or ipv6) rather than ipv4-addr
  * new optional "prefix" attribute that can be used in place of "netmask"
  * new optional "family" attribute - "ipv4" or "ipv6"
    (will default to ipv4)
  * define data types for the above
* tests/networkxml2xml(in|out)/nat-network.xml: add multiple <ip> elements
  (including IPv6) to a single network definition to verify they are being
  correctly parsed and formatted.