Re: [PATCH 3/4] network: firewalld: add policies for routed networks
On Thu, May 12, 2022 at 07:42:43PM +0100, Daniel P. Berrangé wrote:
On Wed, May 11, 2022 at 11:41:54AM -0400, Eric Garver wrote:
> Signed-off-by: Eric Garver <eric(a)garver.life>
> ---
> src/network/libvirt-routed-in.policy | 11 +++++++++++
> src/network/libvirt-routed-out.policy | 12 ++++++++++++
> src/network/meson.build | 10 ++++++++++
> 3 files changed, 33 insertions(+)
> create mode 100644 src/network/libvirt-routed-in.policy
> create mode 100644 src/network/libvirt-routed-out.policy
>
> diff --git a/src/network/libvirt-routed-in.policy
b/src/network/libvirt-routed-in.policy
> new file mode 100644
> index 000000000000..baf8822d747c
> --- /dev/null
> +++ b/src/network/libvirt-routed-in.policy
> @@ -0,0 +1,11 @@
> +<?xml version="1.0" encoding="utf-8"?>
> +<policy target="ACCEPT">
> + <short>libvirt-routed-out</short>
> +
> + <description>
> + This policy is used to allow routed traffic to the virtual machines.
> + </description>
> +
> + <ingress-zone name="ANY" />
> + <egress-zone name="libvirt-routed" />
> +</policy>
Same as the NAT version of the policy so makes sense.
> diff --git a/src/network/libvirt-routed-out.policy
b/src/network/libvirt-routed-out.policy
> new file mode 100644
> index 000000000000..efa0030569d6
> --- /dev/null
> +++ b/src/network/libvirt-routed-out.policy
> @@ -0,0 +1,12 @@
> +<?xml version="1.0" encoding="utf-8"?>
> +<policy target="ACCEPT">
> + <short>libvirt-routed-out</short>
> +
> + <description>
> + This policy is used to allow routed virtual machine traffic to the rest of
> + the network.
> + </description>
> +
> + <ingress-zone name="libvirt-routed" />
> + <egress-zone name="ANY" />
> +</policy>
This is much more permissive than what I expected. Doesn't
this allow the VMs to have unrestricted access to anything
on the host ?
No. ANY means any zone. i.e. FORWARD.
There is another symbolic zone, HOST, that is used for INPUT.
At a libvirt POV, the NAT and routed zones should be
identical, with the only difference being whether
masquerading is applied.
I think the additional difference is that routed allows connections
originating from outside (world -> libvirt) to the VMs. There is no "in"
policy for NAT for the same reason - they should always be denied.
In both NAT and routed, connections originating from VMs allow the
return path implicitly via conntrack state.
In terms of VM -> host, we still only want to allow the
small set of services, dns, dhcp, ssh AFAIK.
Right, that's covered by the libvirt-to-host policy and is common
between the NAT and routed networks.
With regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|