This patch implements support for learning a VM's IP address. It uses
the pcap library to listen on the VM's backend network interface (tap)
or the physical ethernet device (macvtap) and tries to capture packets
with source or destination MAC address of the VM and learn from DHCP
Offers, ARP traffic, or first-sent IPv4 packet what the IP address of
the VM's interface is. This then allows to instantiate the network
traffic filtering rules without the user having to provide the IP
parameter somewhere in the filter description or in the interface
description as a parameter. This only supports to detect the parameter
IP, which is for the assumed single IPv4 address of a VM. There is not
support for interfaces that may have multiple IP addresses (IP
aliasing) or IPv6 that may then require more than one valid IP address
to be detected. A VM can have multiple independent interfaces that each
uses a different IP address and in that case it will be attempted to
detect each one of the address independently.
So, when for example an interface description in the domain XML has
looked like this up to now:
<interface type='bridge'>
<source bridge='mybridge'/>
<model type='virtio'/>
<filterref filter='clean-traffic'>
<parameter name='IP' value='10.2.3.4'/>
</filterref>
</interface>
you may omit the IP parameter:
<interface type='bridge'>
<source bridge='mybridge'/>
<model type='virtio'/>
<filterref filter='clean-traffic'/>
</interface>
Internally I am walking the 'tree' of a VM's referenced network filters
and determine with the given variables which variables are missing. Now,
the above IP parameter may be missing and this causes a libvirt-internal
thread to be started that uses the pcap library's API to listen to the
backend interface (in case of macvtap to the physical interface) in an
attempt to determine the missing IP parameter. If the backend interface
disappears the thread terminates assuming the VM was brought down. In
case of a macvtap device a timeout is being used to wait for packets
from the given VM (filtering by VM's interface MAC address). If the VM's
macvtap device disappeared the thread also terminates. In all other
cases it tries to determine the IP address of the VM and will then apply
the rules late on the given interface, which would have happened
immediately if the IP parameter had been explicitly given. In case an
error happens while the firewall rules are applied, the VM's backend
interface is 'down'ed preventing it to communicate. Reasons for failure
for applying the network firewall rules may that an ebtables/iptables
command failes or OOM errors. Essentially the same failure reasons may
occur as when the firewall rules are applied immediately on VM start,
except that due to the late application of the filtering rules the VM
now is already running and cannot be hindered anymore from starting.
Bringing down the whole VM would probably be considered too drastic.
While a VM's IP address is attempted to be determined only limited
updates to network filters are allowed. In particular it is prevented
that filters are modified in such a way that they would introduce new
variables.
A caveat: The algorithm does not know which one is the appropriate IP
address of a VM. If the VM spoofs an IP address in its first ARP traffic
or IPv4 packets its filtering rules will be instantiated for this IP
address, thus 'locking' it to the found IP address. So, it's still
'safer' to explicitly provide the IP address of a VM's interface in the
filter description if it is known beforehand.
* configure.ac: detect libpcap
* libvirt.spec.in: require libpcap[-devel] if qemu is built
* src/internal.h: add the new ATTRIBUTE_PACKED define
* src/Makefile.am src/libvirt_private.syms: add the new modules and symbols
* src/nwfilter/nwfilter_learnipaddr.[ch]: new module being added
* src/nwfilter/nwfilter_driver.c src/conf/nwfilter_conf.[ch]
src/nwfilter/nwfilter_ebiptables_driver.[ch]
src/nwfilter/nwfilter_gentech_driver.[ch]: plu the new functionality in
* tests/nwfilterxml2xmltest: extend testing
* cfg.mk (sc_prohibit_test_minus_ao): Also check for [.
* docs/Makefile.am (%.html, html/index.html): Avoid non-portable
test usage.
* libvirt.spec.in (%post): Likewise.
* tools/virt-pki-validate.in (servercert.pem): Likewise.
* configure.ac (LOGNAME): Use test, not [, in files processed by
autoconf.
Detected by Matthias Bolte.
This patch adds IPv6 filtering support for the following protocols:
- tcp-ipv6
- udp-ipv6
- udplite-ipv6
- esp-ipv6
- ah-ipv6
- sctp-ipv6
- all-ipv6
- icmpv6
Many of the IPv4 data structure could be re-used for IPv6 support.
Since ip6tables also supports pretty much the same command line parameters
as iptables does, also much of the code could be re-used and now
command lines are invoked with the ip(6)tables tool parameter passed
through the functions as a parameter.
This patch adds support for L3/L4 filtering using iptables. This adds
support for 'tcp', 'udp', 'icmp', 'igmp', 'sctp' etc. filtering.
As mentioned in the introduction, a .c file provided by this patch
is #include'd into a .c file. This will need work, but should be alright
for review.
Signed-off-by: Stefan Berger <stefanb@us.ibm.com>
This patch implements the core driver and provides
- management functionality for managing the filter XMLs
- compiling the internal filter representation into ebtables rules
- applying ebtables rules on a network (tap,macvtap) interface
- tearing down ebtables rules that were applied on behalf of an
interface
- updating of filters while VMs are running and causing the firewalls to
be rebuilt
- other bits and pieces
Signed-off-by: Stefan Berger <stefanb@us.ibm.com>
* configure.ac libvirt.spec.in: update with new version
* docs/news.html.in: add list of changes in 0.7.7
* po/*po*: updated spanish and russian localisations, rebuilt
With the recent changes to the linking defaults in Fedora 13 (namely
enabling --no-add-needed behaviour by default), we have to pass the
dlopen()-providing libraries directly at the link of the module; use the
same AC_SEARCH_LIBS function as used before to look for it and add it to
the Makefile.
since we're using gettext-0.14.1, which uses that now-obsolete
automake symbol. Otherwise, make distcheck would fails like this:
make[2]: Entering directory `/t/libvirt-0.7.6/_build/po'
/bin/sh @MKINSTALLDIRS@ /t/libvirt-0.7.6/_inst/share
/bin/sh: @MKINSTALLDIRS@: No such file or directory
make[2]: *** [install-data-yes] Error 127
* configure.ac (MKINSTALLDIRS): Define.
For reference, we're currently hamstrung by our desire
to support RHEL5, which still uses gettext-0.14:
http://bugzilla.redhat.com/523713
Create the filesystem on the partition used by the pool
* configure.ac: check for mkfs availability
* libvirt.spec.in: add extra require on util-linux for mkfs
* src/storage/storage_backend_fs.c: run mkfs with the expected
fs type when creating a filesystem pool
This patch adds build support for libvirt checking for certain contents
of /usr/include/linux/if_link.h to see whether macvtap support is
compilable on that system. One can disable macvtap support in libvirt
via --without-macvtap passed to configure.
* configure.ac src/Makefile.am: new build support
* src/libvirt_macvtap.syms: list of exported symbols
* src/util/macvtap.c: empty module to not break compilation
Stefan Berger