[PATCH 15/29] docs: Convert 'firewall' page to rST
Peter Krempa
pkrempa at redhat.com
Mon Mar 28 12:10:30 UTC 2022
Signed-off-by: Peter Krempa <pkrempa at redhat.com>
---
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docs/meson.build | 2 +-
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-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE html>
-<html xmlns="http://www.w3.org/1999/xhtml">
- <body>
- <h1 >Firewall and network filtering in libvirt</h1>
- <p>There are three pieces of libvirt functionality which do network
- filtering of some type.
- <br /><br />
- At a high level they are:
- </p>
- <ul>
- <li>The virtual network driver
- <br /><br />
- This provides an isolated bridge device (ie no physical NICs
- attached). Guest TAP devices are attached to this bridge.
- Guests can talk to each other and the host, and optionally the
- wider world.
- <br /><br />
- </li>
- <li>The QEMU driver MAC filtering
- <br /><br />
- This provides a generic filtering of MAC addresses to prevent
- the guest spoofing its MAC address. This is mostly obsoleted by
- the next item, so won't be discussed further.
- <br /><br />
- </li>
- <li>The network filter driver
- <br /><br />
- This provides fully configurable, arbitrary network filtering
- of traffic on guest NICs. Generic rulesets are defined at the
- host level to control traffic in some manner. Rules sets are
- then associated with individual NICs of a guest. While not as
- expressive as directly using iptables/ebtables, this can still
- do nearly everything you would want to on a guest NIC filter.
- </li>
- </ul>
-
- <h3><a id="fw-virtual-network-driver">The virtual network driver</a>
- </h3>
- <p>The typical configuration for guests is to use bridging of the
- physical NIC on the host to connect the guest directly to the LAN.
- In RHEL6 there is also the possibility of using macvtap/sr-iov
- and VEPA connectivity. None of this stuff plays nicely with wireless
- NICs, since they will typically silently drop any traffic with a
- MAC address that doesn't match that of the physical NIC.
- </p>
- <p>Thus the virtual network driver in libvirt was invented. This takes
- the form of an isolated bridge device (ie one with no physical NICs
- attached). The TAP devices associated with the guest NICs are attached
- to the bridge device. This immediately allows guests on a single host
- to talk to each other and to the host OS (modulo host IPtables rules).
- </p>
- <p>libvirt then uses iptables to control what further connectivity is
- available. There are three configurations possible for a virtual
- network at time of writing:
- </p>
- <ul>
- <li>isolated: all off-node traffic is completely blocked</li>
- <li>nat: outbound traffic to the LAN is allowed, but MASQUERADED</li>
- <li>forward: outbound traffic to the LAN is allowed</li>
- </ul>
- <p>The latter 'forward' case requires the virtual network be on a
- separate sub-net from the main LAN, and that the LAN admin has
- configured routing for this subnet. In the future we intend to
- add support for IP subnetting and/or proxy-arp. This allows for
- the virtual network to use the same subnet as the main LAN and
- should avoid need for the LAN admin to configure special routing.
- </p>
- <p>Libvirt will optionally also provide DHCP services to the virtual
- network using DNSMASQ. In all cases, we need to allow DNS/DHCP
- queries to the host OS. Since we can't predict whether the host
- firewall setup is already allowing this, we insert 4 rules into
- the head of the INPUT chain
- </p>
- <pre>
-target prot opt in out source destination
-ACCEPT udp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:53
-ACCEPT tcp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:53
-ACCEPT udp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:67
-ACCEPT tcp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:67</pre>
- <p>Note we have restricted our rules to just the bridge associated
- with the virtual network, to avoid opening undesirable holes in
- the host firewall wrt the LAN/WAN.
- </p>
- <p>The next rules depend on the type of connectivity allowed, and go
- in the main FORWARD chain:
- </p>
- <ul>
- <li>type=isolated
- <br /><br />
-Allow traffic between guests. Deny inbound. Deny outbound.
- <pre>
-target prot opt in out source destination
-ACCEPT all -- virbr1 virbr1 0.0.0.0/0 0.0.0.0/0
-REJECT all -- * virbr1 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
-REJECT all -- virbr1 * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable</pre>
- </li>
- <li>type=nat
- <br /><br />
-Allow inbound related to an established connection. Allow
-outbound, but only from our expected subnet. Allow traffic
-between guests. Deny all other inbound. Deny all other outbound.
- <pre>
-target prot opt in out source destination
-ACCEPT all -- * virbr0 0.0.0.0/0 192.168.122.0/24 state RELATED,ESTABLISHED
-ACCEPT all -- virbr0 * 192.168.122.0/24 0.0.0.0/0
-ACCEPT all -- virbr0 virbr0 0.0.0.0/0 0.0.0.0/0
-REJECT all -- * virbr0 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
-REJECT all -- virbr0 * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable</pre>
- </li>
- <li>type=routed
- <br /><br />
-Allow inbound, but only to our expected subnet. Allow
-outbound, but only from our expected subnet. Allow traffic
-between guests. Deny all other inbound. Deny all other outbound.
- <pre>
-target prot opt in out source destination
-ACCEPT all -- * virbr2 0.0.0.0/0 192.168.124.0/24
-ACCEPT all -- virbr2 * 192.168.124.0/24 0.0.0.0/0
-ACCEPT all -- virbr2 virbr2 0.0.0.0/0 0.0.0.0/0
-REJECT all -- * virbr2 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
-REJECT all -- virbr2 * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable</pre>
- </li>
- <li>Finally, with type=nat, there is also an entry in the POSTROUTING
-chain to apply masquerading:
- <pre>
-target prot opt in out source destination
-MASQUERADE all -- * * 192.168.122.0/24 !192.168.122.0/24</pre>
- </li>
- </ul>
-
- <h3><a id="fw-firewalld-and-virtual-network-driver">firewalld and the virtual network driver</a>
- </h3>
- <p>
- If <a href="https://firewalld.org">firewalld</a> is active on
- the host, libvirt will attempt to place the bridge interface of
- a libvirt virtual network into the firewalld zone named
- "libvirt" (thus making all guest->host traffic on that network
- subject to the rules of the "libvirt" zone). This is done
- because, if firewalld is using its nftables backend (available
- since firewalld 0.6.0) the default firewalld zone (which would
- be used if libvirt didn't explicitly set the zone) prevents
- forwarding traffic from guests through the bridge, as well as
- preventing DHCP, DNS, and most other traffic from guests to
- host. The zone named "libvirt" is installed into the firewalld
- configuration by libvirt (not by firewalld), and allows
- forwarded traffic through the bridge as well as DHCP, DNS, TFTP,
- and SSH traffic to the host - depending on firewalld's backend
- this will be implemented via either iptables or nftables
- rules. libvirt's own rules outlined above will *always* be
- iptables rules regardless of which backend is in use by
- firewalld.
- </p>
- <p>
- NB: It is possible to manually set the firewalld zone for a
- network's interface with the "zone" attribute of the network's
- "bridge" element.
- </p>
- <p>
- NB: Prior to libvirt 5.1.0, the firewalld "libvirt" zone did not
- exist, and prior to firewalld 0.7.0 a feature crucial to making
- the "libvirt" zone operate properly (rich rule priority
- settings) was not implemented in firewalld. In cases where one
- or the other of the two packages is missing the necessary
- functionality, it's still possible to have functional guest
- networking by setting the firewalld backend to "iptables" (in
- firewalld prior to 0.6.0, this was the only backend available).
- </p>
-
- <h3><a id="fw-network-filter-driver">The network filter driver</a>
- </h3>
- <p>This driver provides a fully configurable network filtering capability
- that leverages ebtables, iptables and ip6tables. This was written by
- the libvirt guys at IBM and although its XML schema is defined by libvirt,
- the conceptual model is closely aligned with the DMTF CIM schema for
- network filtering:
- </p>
- <p><a href="https://www.dmtf.org/standards/cim/cim_schema_v2230/CIM_Network.pdf">https://www.dmtf.org/standards/cim/cim_schema_v2230/CIM_Network.pdf</a></p>
- <p>The filters are managed in libvirt as a top level, standalone object.
- This allows the filters to then be referenced by any libvirt object
- that requires their functionality, instead tying them only to use
- by guest NICs. In the current implementation, filters can be associated
- with individual guest NICs via the libvirt domain XML format. In the
- future we might allow filters to be associated with the virtual network
- objects. Further we're expecting to define a new 'virtual switch' object
- to remove the complexity of configuring bridge/sriov/vepa networking
- modes. This make also end up making use of network filters.
- </p>
- <p>There are a new set of virsh commands for managing network filters:</p>
- <ul>
- <li>virsh nwfilter-define
- <br /><br />
- define or update a network filter from an XML file
- <br /><br />
- </li>
- <li>virsh nwfilter-undefine
- <br /><br />
- undefine a network filter
- <br /><br />
- </li>
- <li>virsh nwfilter-dumpxml
- <br /><br />
- network filter information in XML
- <br /><br />
- </li>
- <li>virsh nwfilter-list
- <br /><br />
- list network filters
- <br /><br />
- </li>
- <li>virsh nwfilter-edit
- <br /><br />
- edit XML configuration for a network filter
- </li>
- </ul>
- <p>There are equivalently named C APIs for each of these commands.</p>
- <p>As with all objects libvirt manages, network filters are configured
-using an XML format. At a high level the format looks like this:
- </p>
-<pre>
-<filter name='no-spamming' chain='XXXX'>
- <uuid>d217f2d7-5a04-0e01-8b98-ec2743436b74</uuid>
-
- <rule ...>
- ....
- </rule>
-
- <filterref filter='XXXX'/>
-</filter></pre>
- <p>Every filter has a name and UUID which serve as unique identifiers.
- A filter can have zero-or-more <code><rule></code> elements which
- are used to actually define network controls. Filters can be arranged
- into a DAG, so zero-or-more <code><filterref/></code> elements are
- also allowed. Cycles in the graph are not allowed.
- </p>
- <p>The <code><rule></code> element is where all the interesting stuff
- happens. It has three attributes, an action, a traffic direction and an
- optional priority. E.g.:
- </p>
- <pre><rule action='drop' direction='out' priority='500'></pre>
- <p>Within the rule there are a wide variety of elements allowed, which
- do protocol specific matching. Supported protocols currently include
- <code>mac</code>, <code>arp</code>, <code>rarp</code>, <code>ip</code>,
- <code>ipv6</code>, <code>tcp/ip</code>, <code>icmp/ip</code>,
- <code>igmp/ip</code>, <code>udp/ip</code>, <code>udplite/ip</code>,
- <code>esp/ip</code>, <code>ah/ip</code>, <code>sctp/ip</code>,
- <code>tcp/ipv6</code>, <code>icmp/ipv6</code>, <code>igmp/ipv6</code>,
- <code>udp/ipv6</code>, <code>udplite/ipv6</code>, <code>esp/ipv6</code>,
- <code>ah/ipv6</code>, <code>sctp/ipv6</code>. Each protocol defines what
- is valid inside the <rule> element. The general pattern though is:
- </p>
- <pre>
-<protocol match='yes|no' attribute1='value1' attribute2='value2'/></pre>
- <p>So, eg a TCP protocol, matching ports 0-1023 would be expressed as:</p>
- <pre><tcp match='yes' srcportstart='0' srcportend='1023'/></pre>
- <p>Attributes can included references to variables defined by the
- object using the rule. So the guest XML format allows each NIC
- to have a MAC address and IP address defined. These are made
- available to filters via the variables <code><b>$IP</b></code> and
- <code><b>$MAC</b></code>.
- </p>
- <p>So to define a filter that prevents IP address spoofing we can
- simply match on source IP address <code>!= $IP</code> like this:
- </p>
- <pre>
-<filter name='no-ip-spoofing' chain='ipv4'>
- <rule action='drop' direction='out'>
- <ip match='no' srcipaddr='<b>$IP</b>' />
- </rule>
-</filter></pre>
- <p>I'm not going to go into details on all the other protocol
- matches you can do, because it'll take far too much space.
- You can read about the options
- <a href="formatnwfilter.html#nwfelemsRulesProto">here</a>.
- </p>
- <p>Out of the box in RHEL6/Fedora rawhide, libvirt ships with a
- set of default useful rules:
- </p>
- <pre>
-# virsh nwfilter-list
-UUID Name
-----------------------------------------------------------------
-15b1ab2b-b1ac-1be2-ed49-2042caba4abb allow-arp
-6c51a466-8d14-6d11-46b0-68b1a883d00f allow-dhcp
-7517ad6c-bd90-37c8-26c9-4eabcb69848d allow-dhcp-server
-7680776c-77aa-496f-90d6-13097664b925 allow-dhcpv6
-9cdaad60-7631-4172-8ccb-ef774be7485b allow-dhcpv6-server
-3d38b406-7cf0-8335-f5ff-4b9add35f288 allow-incoming-ipv4
-908543c1-902e-45f6-a6ca-1a0ad35e7599 allow-incoming-ipv6
-5ff06320-9228-2899-3db0-e32554933415 allow-ipv4
-ce8904cc-ad3a-4454-896c-53452882f817 allow-ipv6
-db0b1767-d62b-269b-ea96-0cc8b451144e clean-traffic
-6d6ddcc8-1242-4c43-ac63-63af80493132 clean-traffic-gateway
-4cf38077-c7d5-4e25-99bb-6c4c9efad294 no-arp-ip-spoofing
-0b11a636-ce58-497f-be90-17f63c92487a no-arp-mac-spoofing
-f88f1932-debf-4aa1-9fbe-f10d3aa4bc95 no-arp-spoofing
-772f112d-52e4-700c-0250-e178a3d91a7a no-ip-multicast
-7ee20370-8106-765d-f7ff-8a60d5aaf30b no-ip-spoofing
-f8a51c43-a08f-49b3-b9e2-393d54522dc0 no-ipv6-multicast
-a7f0afe9-a428-44b8-8566-c8ee2a669271 no-ipv6-spoofing
-d5d3c490-c2eb-68b1-24fc-3ee362fc8af3 no-mac-broadcast
-fb57c546-76dc-a372-513f-e8179011b48a no-mac-spoofing
-dba10ea7-446d-76de-346f-335bd99c1d05 no-other-l2-traffic
-f5c78134-9da4-0c60-a9f0-fb37bc21ac1f no-other-rarp-traffic
-7637e405-4ccf-42ac-5b41-14f8d03d8cf3 qemu-announce-self
-9aed52e7-f0f3-343e-fe5c-7dcb27b594e5 qemu-announce-self-rarp</pre>
- <p>Most of these are just building blocks. The interesting one here
- is 'clean-traffic'. This pulls together all the building blocks
- into one filter that you can then associate with a guest NIC.
- This stops the most common bad things a guest might try, IP
- spoofing, arp spoofing and MAC spoofing. To look at the rules for
- any of these just do:
- </p>
- <pre>virsh nwfilter-dumpxml FILTERNAME|UUID</pre>
- <p>They are all stored in <code>/etc/libvirt/nwfilter</code>, but don't
- edit the files there directly. Use <code>virsh nwfilter-define</code>
- to update them. This ensures the guests have their iptables/ebtables
- rules recreated.
- </p>
- <p>To associate the clean-traffic filter with a guest, edit the
- guest XML config and change the <code><interface></code> element
- to include a <code><filterref></code> and also specify the
- <code><ip address/></code> that the guest is allowed to
- use:
- </p>
- <pre>
-<interface type='bridge'>
- <mac address='52:54:00:56:44:32'/>
- <source bridge='br1'/>
- <ip address='10.33.8.131'/>
- <target dev='vnet0'/>
- <model type='virtio'/>
- <filterref filter='clean-traffic'/>
-</interface></pre>
- <p>If no <code><ip address></code> is included, the network filter
- driver will activate its 'learning mode'. This uses libpcap to snoop on
- network traffic the guest sends and attempts to identify the
- first IP address it uses. It then locks traffic to this address.
- Obviously this isn't entirely secure, but it does offer some
- protection against the guest being trojaned once up and running.
- In the future we intend to enhance the learning mode so that it
- looks for DHCPOFFERS from a trusted DHCP server and only allows
- the offered IP address to be used.
- </p>
- <p>Now, how is all this implemented...?</p>
- <p>The network filter driver uses a combination of ebtables, iptables and
- ip6tables, depending on which protocols are referenced in a filter. The
- out of the box 'clean-traffic' filter rules only require use of
- ebtables. If you want to do matching at tcp/udp/etc protocols (eg to add
- a new filter 'no-email-spamming' to block port 25), then iptables will
- also be used.
- </p>
- <p>The driver attempts to keep its rules separate from those that
- the host admin might already have configured. So the first thing
- it does with ebtables, is to add two hooks in POSTROUTING and
- PREROUTING chains, to redirect traffic to custom chains. These
- hooks match on the TAP device name of the guest NIC, so they
- should not interact badly with any administrator defined rules:
- </p>
- <pre>
-Bridge chain: PREROUTING, entries: 1, policy: ACCEPT
--i vnet0 -j libvirt-I-vnet0
-
-Bridge chain: POSTROUTING, entries: 1, policy: ACCEPT
--o vnet0 -j libvirt-O-vnet0</pre>
- <p>To keep things manageable and easy to follow, the driver will then
- create further sub-chains for each protocol then it needs to match
- against:
- </p>
- <pre>
-Bridge chain: libvirt-I-vnet0, entries: 5, policy: ACCEPT
--p IPv4 -j I-vnet0-ipv4
--p ARP -j I-vnet0-arp
--p 0x8035 -j I-vnet0-rarp
--p 0x835 -j ACCEPT
--j DROP
-
-Bridge chain: libvirt-O-vnet0, entries: 4, policy: ACCEPT
--p IPv4 -j O-vnet0-ipv4
--p ARP -j O-vnet0-arp
--p 0x8035 -j O-vnet0-rarp
--j DROP</pre>
- <p>Finally, here comes the actual implementation of the filters. This
- example shows the 'clean-traffic' filter implementation.
- I'm not going to explain what this is doing now. :-)
- </p>
- <pre>
-Bridge chain: I-vnet0-ipv4, entries: 2, policy: ACCEPT
--s ! 52:54:0:56:44:32 -j DROP
--p IPv4 --ip-src ! 10.33.8.131 -j DROP
-
-Bridge chain: O-vnet0-ipv4, entries: 1, policy: ACCEPT
--j ACCEPT
-
-Bridge chain: I-vnet0-arp, entries: 6, policy: ACCEPT
--s ! 52:54:0:56:44:32 -j DROP
--p ARP --arp-mac-src ! 52:54:0:56:44:32 -j DROP
--p ARP --arp-ip-src ! 10.33.8.131 -j DROP
--p ARP --arp-op Request -j ACCEPT
--p ARP --arp-op Reply -j ACCEPT
--j DROP
-
-Bridge chain: O-vnet0-arp, entries: 5, policy: ACCEPT
--p ARP --arp-op Reply --arp-mac-dst ! 52:54:0:56:44:32 -j DROP
--p ARP --arp-ip-dst ! 10.33.8.131 -j DROP
--p ARP --arp-op Request -j ACCEPT
--p ARP --arp-op Reply -j ACCEPT
--j DROP
-
-Bridge chain: I-vnet0-rarp, entries: 2, policy: ACCEPT
--p 0x8035 -s 52:54:0:56:44:32 -d Broadcast --arp-op Request_Reverse --arp-ip-src 0.0.0.0 --arp-ip-dst 0.0.0.0 --arp-mac-src 52:54:0:56:44:32 --arp-mac-dst 52:54:0:56:44:32 -j ACCEPT
--j DROP
-
-Bridge chain: O-vnet0-rarp, entries: 2, policy: ACCEPT
--p 0x8035 -d Broadcast --arp-op Request_Reverse --arp-ip-src 0.0.0.0 --arp-ip-dst 0.0.0.0 --arp-mac-src 52:54:0:56:44:32 --arp-mac-dst 52:54:0:56:44:32 -j ACCEPT
--j DROP</pre>
- <p>NB, we would have liked to include the prefix 'libvirt-' in all
- of our chain names, but unfortunately the kernel limits names
- to a very short maximum length. So only the first two custom
- chains can include that prefix. The others just include the
- TAP device name + protocol name.
- </p>
- <p>If I define a new filter 'no-spamming' and then add this to the
- 'clean-traffic' filter, I can illustrate how iptables usage works:
- </p>
- <pre>
-# cat > /root/spamming.xml <<EOF
-<filter name='no-spamming' chain='root'>
- <uuid>d217f2d7-5a04-0e01-8b98-ec2743436b74</uuid>
- <rule action='drop' direction='out' priority='500'>
- <tcp dstportstart='25' dstportend='25'/>
- </rule>
-</filter>
-EOF
-# virsh nwfilter-define /root/spamming.xml
-# virsh nwfilter-edit clean-traffic</pre>
-
- <p>...add <code><filterref filter='no-spamming'/></code></p>
- <p>All active guests immediately have their iptables/ebtables rules
- rebuilt.
- </p>
- <p>The network filter driver deals with iptables in a very similar
- way. First it separates out its rules from those the admin may
- have defined, by adding a couple of hooks into the INPUT/FORWARD
- chains:
- </p>
- <pre>
-Chain INPUT (policy ACCEPT 13M packets, 21G bytes)
-target prot opt in out source destination
-libvirt-host-in all -- * * 0.0.0.0/0 0.0.0.0/0
-
-Chain FORWARD (policy ACCEPT 5532K packets, 3010M bytes)
-target prot opt in out source destination
-libvirt-in all -- * * 0.0.0.0/0 0.0.0.0/0
-libvirt-out all -- * * 0.0.0.0/0 0.0.0.0/0
-libvirt-in-post all -- * * 0.0.0.0/0 0.0.0.0/0</pre>
- <p>These custom chains then do matching based on the TAP device
- name, so they won't open holes in the admin defined matches for
- the LAN/WAN (if any).
- </p>
- <pre>
-Chain libvirt-host-in (1 references)
- target prot opt in out source destination
- HI-vnet0 all -- * * 0.0.0.0/0 0.0.0.0/0 [goto] PHYSDEV match --physdev-in vnet0
-
-Chain libvirt-in (1 references)
- target prot opt in out source destination
- FI-vnet0 all -- * * 0.0.0.0/0 0.0.0.0/0 [goto] PHYSDEV match --physdev-in vnet0
-
-Chain libvirt-in-post (1 references)
- target prot opt in out source destination
- ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 PHYSDEV match --physdev-in vnet0
-
-Chain libvirt-out (1 references)
- target prot opt in out source destination
- FO-vnet0 all -- * * 0.0.0.0/0 0.0.0.0/0 [goto] PHYSDEV match --physdev-out vnet0</pre>
- <p>Finally, we can see the interesting bit which is the actual
- implementation of my filter to block port 25 access:
- </p>
- <pre>
-Chain FI-vnet0 (1 references)
- target prot opt in out source destination
- DROP tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:25
-
-Chain FO-vnet0 (1 references)
- target prot opt in out source destination
- DROP tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:25
-
-Chain HI-vnet0 (1 references)
- target prot opt in out source destination
- DROP tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:25</pre>
- <p>One thing in looking at this you may notice is that if there
- are many guests all using the same filters, we will be duplicating
- the iptables rules over and over for each guest. This is merely a
- limitation of the current rules engine implementation. At the libvirt
- object modelling level you can clearly see we've designed the model
- so filter rules are defined in one place, and indirectly referenced
- by guests. Thus it should be possible to change the implementation in
- the future so we can share the actual iptables/ebtables rules for
- each guest to create a more scalable system. The stuff in current libvirt
- is more or less the very first working implementation we've had of this,
- so there's not been much optimization work done yet.
- </p>
- <p>Also notice that at the XML level we don't expose the fact we
- are using iptables or ebtables at all. The rule definition is done in
- terms of network protocols. Thus if we ever find a need, we could
- plug in an alternative implementation that calls out to a different
- firewall implementation instead of ebtables/iptables (providing that
- implementation was suitably expressive of course)
- </p>
- <p>Finally, in terms of problems we have in deployment. The biggest
- problem is that if the admin does <code>service iptables restart</code>
- all our work gets blown away. We've experimented with using lokkit
- to record our custom rules in a persistent config file, but that
- caused different problem. Admins who were not using lokkit for
- their config found that all their own rules got blown away. So
- we threw away our lokkit code. Instead we document that if you
- run <code>service iptables restart</code>, you need to send SIGHUP to
- libvirt to make it recreate its rules.
- </p>
- <p>More in depth documentation on this is <a href="formatnwfilter.html">here</a>.</p>
- </body>
-</html>
diff --git a/docs/firewall.rst b/docs/firewall.rst
new file mode 100644
index 0000000000..adda0ef1f4
--- /dev/null
+++ b/docs/firewall.rst
@@ -0,0 +1,506 @@
+=========================================
+Firewall and network filtering in libvirt
+=========================================
+
+.. contents::
+
+There are three pieces of libvirt functionality which do network filtering of
+some type. At a high level they are:
+
+- The virtual network driver
+
+ This provides an isolated bridge device (ie no physical NICs attached).
+ Guest TAP devices are attached to this bridge. Guests can talk to each
+ other and the host, and optionally the wider world.
+
+- The QEMU driver MAC filtering
+
+ This provides a generic filtering of MAC addresses to prevent the guest
+ spoofing its MAC address. This is mostly obsoleted by the next item, so
+ won't be discussed further.
+
+- The network filter driver
+
+ This provides fully configurable, arbitrary network filtering of traffic on
+ guest NICs. Generic rulesets are defined at the host level to control
+ traffic in some manner. Rules sets are then associated with individual NICs
+ of a guest. While not as expressive as directly using iptables/ebtables,
+ this can still do nearly everything you would want to on a guest NIC
+ filter.
+
+The virtual network driver
+--------------------------
+
+The typical configuration for guests is to use bridging of the physical NIC on
+the host to connect the guest directly to the LAN. In RHEL6 there is also the
+possibility of using macvtap/sr-iov and VEPA connectivity. None of this stuff
+plays nicely with wireless NICs, since they will typically silently drop any
+traffic with a MAC address that doesn't match that of the physical NIC.
+
+Thus the virtual network driver in libvirt was invented. This takes the form of
+an isolated bridge device (ie one with no physical NICs attached). The TAP
+devices associated with the guest NICs are attached to the bridge device. This
+immediately allows guests on a single host to talk to each other and to the host
+OS (modulo host IPtables rules).
+
+libvirt then uses iptables to control what further connectivity is available.
+There are three configurations possible for a virtual network at time of
+writing:
+
+- isolated: all off-node traffic is completely blocked
+- nat: outbound traffic to the LAN is allowed, but MASQUERADED
+- forward: outbound traffic to the LAN is allowed
+
+The latter 'forward' case requires the virtual network be on a separate sub-net
+from the main LAN, and that the LAN admin has configured routing for this
+subnet. In the future we intend to add support for IP subnetting and/or
+proxy-arp. This allows for the virtual network to use the same subnet as the
+main LAN and should avoid need for the LAN admin to configure special routing.
+
+Libvirt will optionally also provide DHCP services to the virtual network using
+DNSMASQ. In all cases, we need to allow DNS/DHCP queries to the host OS. Since
+we can't predict whether the host firewall setup is already allowing this, we
+insert 4 rules into the head of the INPUT chain
+
+::
+
+ target prot opt in out source destination
+ ACCEPT udp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:53
+ ACCEPT tcp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:53
+ ACCEPT udp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:67
+ ACCEPT tcp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:67
+
+Note we have restricted our rules to just the bridge associated with the virtual
+network, to avoid opening undesirable holes in the host firewall wrt the
+LAN/WAN.
+
+The next rules depend on the type of connectivity allowed, and go in the main
+FORWARD chain:
+
+- | type=isolated
+ | Allow traffic between guests. Deny inbound. Deny outbound.
+
+ ::
+
+ target prot opt in out source destination
+ ACCEPT all -- virbr1 virbr1 0.0.0.0/0 0.0.0.0/0
+ REJECT all -- * virbr1 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
+ REJECT all -- virbr1 * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
+
+- | type=nat
+ | Allow inbound related to an established connection. Allow outbound, but
+ only from our expected subnet. Allow traffic between guests. Deny all other
+ inbound. Deny all other outbound.
+
+ ::
+
+ target prot opt in out source destination
+ ACCEPT all -- * virbr0 0.0.0.0/0 192.168.122.0/24 state RELATED,ESTABLISHED
+ ACCEPT all -- virbr0 * 192.168.122.0/24 0.0.0.0/0
+ ACCEPT all -- virbr0 virbr0 0.0.0.0/0 0.0.0.0/0
+ REJECT all -- * virbr0 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
+ REJECT all -- virbr0 * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
+
+- | type=routed
+ | Allow inbound, but only to our expected subnet. Allow outbound, but only
+ from our expected subnet. Allow traffic between guests. Deny all other
+ inbound. Deny all other outbound.
+
+ ::
+
+ target prot opt in out source destination
+ ACCEPT all -- * virbr2 0.0.0.0/0 192.168.124.0/24
+ ACCEPT all -- virbr2 * 192.168.124.0/24 0.0.0.0/0
+ ACCEPT all -- virbr2 virbr2 0.0.0.0/0 0.0.0.0/0
+ REJECT all -- * virbr2 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
+ REJECT all -- virbr2 * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
+
+- Finally, with type=nat, there is also an entry in the POSTROUTING chain to
+ apply masquerading:
+
+ ::
+
+ target prot opt in out source destination
+ MASQUERADE all -- * * 192.168.122.0/24 !192.168.122.0/24
+
+firewalld and the virtual network driver
+----------------------------------------
+
+If `firewalld <https://firewalld.org>`__ is active on the host, libvirt will
+attempt to place the bridge interface of a libvirt virtual network into the
+firewalld zone named "libvirt" (thus making all guest->host traffic on that
+network subject to the rules of the "libvirt" zone). This is done because, if
+firewalld is using its nftables backend (available since firewalld 0.6.0) the
+default firewalld zone (which would be used if libvirt didn't explicitly set the
+zone) prevents forwarding traffic from guests through the bridge, as well as
+preventing DHCP, DNS, and most other traffic from guests to host. The zone named
+"libvirt" is installed into the firewalld configuration by libvirt (not by
+firewalld), and allows forwarded traffic through the bridge as well as DHCP,
+DNS, TFTP, and SSH traffic to the host - depending on firewalld's backend this
+will be implemented via either iptables or nftables rules. libvirt's own rules
+outlined above will \*always\* be iptables rules regardless of which backend is
+in use by firewalld.
+
+NB: It is possible to manually set the firewalld zone for a network's interface
+with the "zone" attribute of the network's "bridge" element.
+
+NB: Prior to libvirt 5.1.0, the firewalld "libvirt" zone did not exist, and
+prior to firewalld 0.7.0 a feature crucial to making the "libvirt" zone operate
+properly (rich rule priority settings) was not implemented in firewalld. In
+cases where one or the other of the two packages is missing the necessary
+functionality, it's still possible to have functional guest networking by
+setting the firewalld backend to "iptables" (in firewalld prior to 0.6.0, this
+was the only backend available).
+
+The network filter driver
+-------------------------
+
+This driver provides a fully configurable network filtering capability that
+leverages ebtables, iptables and ip6tables. This was written by the libvirt guys
+at IBM and although its XML schema is defined by libvirt, the conceptual model
+is closely aligned with the DMTF CIM schema for network filtering:
+
+https://www.dmtf.org/standards/cim/cim_schema_v2230/CIM_Network.pdf
+
+The filters are managed in libvirt as a top level, standalone object. This
+allows the filters to then be referenced by any libvirt object that requires
+their functionality, instead tying them only to use by guest NICs. In the
+current implementation, filters can be associated with individual guest NICs via
+the libvirt domain XML format. In the future we might allow filters to be
+associated with the virtual network objects. Further we're expecting to define a
+new 'virtual switch' object to remove the complexity of configuring
+bridge/sriov/vepa networking modes. This make also end up making use of network
+filters.
+
+There are a new set of virsh commands for managing network filters:
+
+- ``virsh nwfilter-define``
+ define or update a network filter from an XML file
+- ``virsh nwfilter-undefine``
+ undefine a network filter
+- ``virsh nwfilter-dumpxml``
+ network filter information in XML
+- ``virsh nwfilter-list``
+ list network filters
+- ``virsh nwfilter-edit``
+ edit XML configuration for a network filter
+
+There are equivalently named C APIs for each of these commands.
+
+As with all objects libvirt manages, network filters are configured using an XML
+format. At a high level the format looks like this:
+
+::
+
+ <filter name='no-spamming' chain='XXXX'>
+ <uuid>d217f2d7-5a04-0e01-8b98-ec2743436b74</uuid>
+
+ <rule ...>
+ ....
+ </rule>
+
+ <filterref filter='XXXX'/>
+ </filter>
+
+Every filter has a name and UUID which serve as unique identifiers. A filter can
+have zero-or-more ``<rule>`` elements which are used to actually define network
+controls. Filters can be arranged into a DAG, so zero-or-more ``<filterref/>``
+elements are also allowed. Cycles in the graph are not allowed.
+
+The ``<rule>`` element is where all the interesting stuff happens. It has three
+attributes, an action, a traffic direction and an optional priority. E.g.:
+
+::
+
+ <rule action='drop' direction='out' priority='500'>
+
+Within the rule there are a wide variety of elements allowed, which do protocol
+specific matching. Supported protocols currently include ``mac``, ``arp``,
+``rarp``, ``ip``, ``ipv6``, ``tcp/ip``, ``icmp/ip``, ``igmp/ip``, ``udp/ip``,
+``udplite/ip``, ``esp/ip``, ``ah/ip``, ``sctp/ip``, ``tcp/ipv6``, ``icmp/ipv6``,
+``igmp/ipv6``, ``udp/ipv6``, ``udplite/ipv6``, ``esp/ipv6``, ``ah/ipv6``,
+``sctp/ipv6``. Each protocol defines what is valid inside the <rule> element.
+The general pattern though is:
+
+::
+
+ <protocol match='yes|no' attribute1='value1' attribute2='value2'/>
+
+So, eg a TCP protocol, matching ports 0-1023 would be expressed as:
+
+::
+
+ <tcp match='yes' srcportstart='0' srcportend='1023'/>
+
+Attributes can included references to variables defined by the object using the
+rule. So the guest XML format allows each NIC to have a MAC address and IP
+address defined. These are made available to filters via the variables ``$IP``
+and ``$MAC``.
+
+So to define a filter that prevents IP address spoofing we can simply match on
+source IP address ``!= $IP`` like this:
+
+::
+
+ <filter name='no-ip-spoofing' chain='ipv4'>
+ <rule action='drop' direction='out'>
+ <ip match='no' srcipaddr='$IP' />
+ </rule>
+ </filter>
+
+I'm not going to go into details on all the other protocol matches you can do,
+because it'll take far too much space. You can read about the options
+`here <formatnwfilter.html#nwfelemsRulesProto>`__.
+
+Out of the box in RHEL6/Fedora rawhide, libvirt ships with a set of default
+useful rules:
+
+::
+
+ # virsh nwfilter-list
+ UUID Name
+ ----------------------------------------------------------------
+ 15b1ab2b-b1ac-1be2-ed49-2042caba4abb allow-arp
+ 6c51a466-8d14-6d11-46b0-68b1a883d00f allow-dhcp
+ 7517ad6c-bd90-37c8-26c9-4eabcb69848d allow-dhcp-server
+ 7680776c-77aa-496f-90d6-13097664b925 allow-dhcpv6
+ 9cdaad60-7631-4172-8ccb-ef774be7485b allow-dhcpv6-server
+ 3d38b406-7cf0-8335-f5ff-4b9add35f288 allow-incoming-ipv4
+ 908543c1-902e-45f6-a6ca-1a0ad35e7599 allow-incoming-ipv6
+ 5ff06320-9228-2899-3db0-e32554933415 allow-ipv4
+ ce8904cc-ad3a-4454-896c-53452882f817 allow-ipv6
+ db0b1767-d62b-269b-ea96-0cc8b451144e clean-traffic
+ 6d6ddcc8-1242-4c43-ac63-63af80493132 clean-traffic-gateway
+ 4cf38077-c7d5-4e25-99bb-6c4c9efad294 no-arp-ip-spoofing
+ 0b11a636-ce58-497f-be90-17f63c92487a no-arp-mac-spoofing
+ f88f1932-debf-4aa1-9fbe-f10d3aa4bc95 no-arp-spoofing
+ 772f112d-52e4-700c-0250-e178a3d91a7a no-ip-multicast
+ 7ee20370-8106-765d-f7ff-8a60d5aaf30b no-ip-spoofing
+ f8a51c43-a08f-49b3-b9e2-393d54522dc0 no-ipv6-multicast
+ a7f0afe9-a428-44b8-8566-c8ee2a669271 no-ipv6-spoofing
+ d5d3c490-c2eb-68b1-24fc-3ee362fc8af3 no-mac-broadcast
+ fb57c546-76dc-a372-513f-e8179011b48a no-mac-spoofing
+ dba10ea7-446d-76de-346f-335bd99c1d05 no-other-l2-traffic
+ f5c78134-9da4-0c60-a9f0-fb37bc21ac1f no-other-rarp-traffic
+ 7637e405-4ccf-42ac-5b41-14f8d03d8cf3 qemu-announce-self
+ 9aed52e7-f0f3-343e-fe5c-7dcb27b594e5 qemu-announce-self-rarp
+
+Most of these are just building blocks. The interesting one here is
+'clean-traffic'. This pulls together all the building blocks into one filter
+that you can then associate with a guest NIC. This stops the most common bad
+things a guest might try, IP spoofing, arp spoofing and MAC spoofing. To look at
+the rules for any of these just do:
+
+::
+
+ virsh nwfilter-dumpxml FILTERNAME|UUID
+
+They are all stored in ``/etc/libvirt/nwfilter``, but don't edit the files there
+directly. Use ``virsh nwfilter-define`` to update them. This ensures the guests
+have their iptables/ebtables rules recreated.
+
+To associate the clean-traffic filter with a guest, edit the guest XML config
+and change the ``<interface>`` element to include a ``<filterref>`` and also
+specify the ``<ip address/>`` that the guest is allowed to use:
+
+::
+
+ <interface type='bridge'>
+ <mac address='52:54:00:56:44:32'/>
+ <source bridge='br1'/>
+ <ip address='10.33.8.131'/>
+ <target dev='vnet0'/>
+ <model type='virtio'/>
+ <filterref filter='clean-traffic'/>
+ </interface>
+
+If no ``<ip address>`` is included, the network filter driver will activate its
+'learning mode'. This uses libpcap to snoop on network traffic the guest sends
+and attempts to identify the first IP address it uses. It then locks traffic to
+this address. Obviously this isn't entirely secure, but it does offer some
+protection against the guest being trojaned once up and running. In the future
+we intend to enhance the learning mode so that it looks for DHCPOFFERS from a
+trusted DHCP server and only allows the offered IP address to be used.
+
+Now, how is all this implemented...?
+
+The network filter driver uses a combination of ebtables, iptables and
+ip6tables, depending on which protocols are referenced in a filter. The out of
+the box 'clean-traffic' filter rules only require use of ebtables. If you want
+to do matching at tcp/udp/etc protocols (eg to add a new filter
+'no-email-spamming' to block port 25), then iptables will also be used.
+
+The driver attempts to keep its rules separate from those that the host admin
+might already have configured. So the first thing it does with ebtables, is to
+add two hooks in POSTROUTING and PREROUTING chains, to redirect traffic to
+custom chains. These hooks match on the TAP device name of the guest NIC, so
+they should not interact badly with any administrator defined rules:
+
+::
+
+ Bridge chain: PREROUTING, entries: 1, policy: ACCEPT
+ -i vnet0 -j libvirt-I-vnet0
+
+ Bridge chain: POSTROUTING, entries: 1, policy: ACCEPT
+ -o vnet0 -j libvirt-O-vnet0
+
+To keep things manageable and easy to follow, the driver will then create
+further sub-chains for each protocol then it needs to match against:
+
+::
+
+ Bridge chain: libvirt-I-vnet0, entries: 5, policy: ACCEPT
+ -p IPv4 -j I-vnet0-ipv4
+ -p ARP -j I-vnet0-arp
+ -p 0x8035 -j I-vnet0-rarp
+ -p 0x835 -j ACCEPT
+ -j DROP
+
+ Bridge chain: libvirt-O-vnet0, entries: 4, policy: ACCEPT
+ -p IPv4 -j O-vnet0-ipv4
+ -p ARP -j O-vnet0-arp
+ -p 0x8035 -j O-vnet0-rarp
+ -j DROP
+
+Finally, here comes the actual implementation of the filters. This example shows
+the 'clean-traffic' filter implementation. I'm not going to explain what this is
+doing now. :-)
+
+::
+
+ Bridge chain: I-vnet0-ipv4, entries: 2, policy: ACCEPT
+ -s ! 52:54:0:56:44:32 -j DROP
+ -p IPv4 --ip-src ! 10.33.8.131 -j DROP
+
+ Bridge chain: O-vnet0-ipv4, entries: 1, policy: ACCEPT
+ -j ACCEPT
+
+ Bridge chain: I-vnet0-arp, entries: 6, policy: ACCEPT
+ -s ! 52:54:0:56:44:32 -j DROP
+ -p ARP --arp-mac-src ! 52:54:0:56:44:32 -j DROP
+ -p ARP --arp-ip-src ! 10.33.8.131 -j DROP
+ -p ARP --arp-op Request -j ACCEPT
+ -p ARP --arp-op Reply -j ACCEPT
+ -j DROP
+
+ Bridge chain: O-vnet0-arp, entries: 5, policy: ACCEPT
+ -p ARP --arp-op Reply --arp-mac-dst ! 52:54:0:56:44:32 -j DROP
+ -p ARP --arp-ip-dst ! 10.33.8.131 -j DROP
+ -p ARP --arp-op Request -j ACCEPT
+ -p ARP --arp-op Reply -j ACCEPT
+ -j DROP
+
+ Bridge chain: I-vnet0-rarp, entries: 2, policy: ACCEPT
+ -p 0x8035 -s 52:54:0:56:44:32 -d Broadcast --arp-op Request_Reverse --arp-ip-src 0.0.0.0 --arp-ip-dst 0.0.0.0 --arp-mac-src 52:54:0:56:44:32 --arp-mac-dst 52:54:0:56:44:32 -j ACCEPT
+ -j DROP
+
+ Bridge chain: O-vnet0-rarp, entries: 2, policy: ACCEPT
+ -p 0x8035 -d Broadcast --arp-op Request_Reverse --arp-ip-src 0.0.0.0 --arp-ip-dst 0.0.0.0 --arp-mac-src 52:54:0:56:44:32 --arp-mac-dst 52:54:0:56:44:32 -j ACCEPT
+ -j DROP
+
+NB, we would have liked to include the prefix 'libvirt-' in all of our chain
+names, but unfortunately the kernel limits names to a very short maximum length.
+So only the first two custom chains can include that prefix. The others just
+include the TAP device name + protocol name.
+
+If I define a new filter 'no-spamming' and then add this to the 'clean-traffic'
+filter, I can illustrate how iptables usage works:
+
+::
+
+ # cat > /root/spamming.xml <<EOF
+ <filter name='no-spamming' chain='root'>
+ <uuid>d217f2d7-5a04-0e01-8b98-ec2743436b74</uuid>
+ <rule action='drop' direction='out' priority='500'>
+ <tcp dstportstart='25' dstportend='25'/>
+ </rule>
+ </filter>
+ EOF
+ # virsh nwfilter-define /root/spamming.xml
+ # virsh nwfilter-edit clean-traffic
+
+...add ``<filterref filter='no-spamming'/>``
+
+All active guests immediately have their iptables/ebtables rules rebuilt.
+
+The network filter driver deals with iptables in a very similar way. First it
+separates out its rules from those the admin may have defined, by adding a
+couple of hooks into the INPUT/FORWARD chains:
+
+::
+
+ Chain INPUT (policy ACCEPT 13M packets, 21G bytes)
+ target prot opt in out source destination
+ libvirt-host-in all -- * * 0.0.0.0/0 0.0.0.0/0
+
+ Chain FORWARD (policy ACCEPT 5532K packets, 3010M bytes)
+ target prot opt in out source destination
+ libvirt-in all -- * * 0.0.0.0/0 0.0.0.0/0
+ libvirt-out all -- * * 0.0.0.0/0 0.0.0.0/0
+ libvirt-in-post all -- * * 0.0.0.0/0 0.0.0.0/0
+
+These custom chains then do matching based on the TAP device name, so they won't
+open holes in the admin defined matches for the LAN/WAN (if any).
+
+::
+
+ Chain libvirt-host-in (1 references)
+ target prot opt in out source destination
+ HI-vnet0 all -- * * 0.0.0.0/0 0.0.0.0/0 [goto] PHYSDEV match --physdev-in vnet0
+
+ Chain libvirt-in (1 references)
+ target prot opt in out source destination
+ FI-vnet0 all -- * * 0.0.0.0/0 0.0.0.0/0 [goto] PHYSDEV match --physdev-in vnet0
+
+ Chain libvirt-in-post (1 references)
+ target prot opt in out source destination
+ ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 PHYSDEV match --physdev-in vnet0
+
+ Chain libvirt-out (1 references)
+ target prot opt in out source destination
+ FO-vnet0 all -- * * 0.0.0.0/0 0.0.0.0/0 [goto] PHYSDEV match --physdev-out vnet0
+
+Finally, we can see the interesting bit which is the actual implementation of my
+filter to block port 25 access:
+
+::
+
+ Chain FI-vnet0 (1 references)
+ target prot opt in out source destination
+ DROP tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:25
+
+ Chain FO-vnet0 (1 references)
+ target prot opt in out source destination
+ DROP tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:25
+
+ Chain HI-vnet0 (1 references)
+ target prot opt in out source destination
+ DROP tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:25
+
+One thing in looking at this you may notice is that if there are many guests all
+using the same filters, we will be duplicating the iptables rules over and over
+for each guest. This is merely a limitation of the current rules engine
+implementation. At the libvirt object modelling level you can clearly see we've
+designed the model so filter rules are defined in one place, and indirectly
+referenced by guests. Thus it should be possible to change the implementation in
+the future so we can share the actual iptables/ebtables rules for each guest to
+create a more scalable system. The stuff in current libvirt is more or less the
+very first working implementation we've had of this, so there's not been much
+optimization work done yet.
+
+Also notice that at the XML level we don't expose the fact we are using iptables
+or ebtables at all. The rule definition is done in terms of network protocols.
+Thus if we ever find a need, we could plug in an alternative implementation that
+calls out to a different firewall implementation instead of ebtables/iptables
+(providing that implementation was suitably expressive of course)
+
+Finally, in terms of problems we have in deployment. The biggest problem is that
+if the admin does ``service iptables restart`` all our work gets blown away.
+We've experimented with using lokkit to record our custom rules in a persistent
+config file, but that caused different problem. Admins who were not using lokkit
+for their config found that all their own rules got blown away. So we threw away
+our lokkit code. Instead we document that if you run
+``service iptables restart``, you need to send SIGHUP to libvirt to make it
+recreate its rules.
+
+More in depth documentation on this is `here <formatnwfilter.html>`__.
diff --git a/docs/meson.build b/docs/meson.build
index 6147f85d16..aa8bad89f0 100644
--- a/docs/meson.build
+++ b/docs/meson.build
@@ -22,7 +22,6 @@ docs_html_in_files = [
'csharp',
'dbus',
'docs',
- 'firewall',
'format',
'formatcaps',
'formatdomaincaps',
@@ -82,6 +81,7 @@ docs_rst_files = [
'drvvmware',
'drvxen',
'errors',
+ 'firewall',
'formatbackup',
'formatcheckpoint',
'formatdomain',
--
2.35.1
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