Hi,
Dnia piątek, 2 sierpnia 2024 12:14:40 CEST David Pineau pisze:
> Hello Neutron Team,
>
> I'm part of a company that is currently migrating from homemade
> software to manage the infrastructure for a virtualization-based
> product towards an openstack based infrastructure.
>
> As such, this platform includes both private and public cloud usages,
> which brings me to our current network problem.
>
> Essentially, as administrators of the system, we want to expose a
> pre-configured network, which provides access to some non-openstack
> managed resources, via some routing mechanisms.
> The various VMs on this network must not be able to see each-other,
> as this network may be exposed to multiple customers/projects.
>
> Note that in this context, we're using the OVN driver for our network stack.
>
> We were initially looking at external networks for this, but understood
> through our attempts and experimentations that:
> - External networks are shared to all projects by default
> - Default sharing of external networks can be disabled by removing the
> automatically injected rbac for '*', allowing us to expose the network to
> only the projects we specify
> - VMs on this network can communicate with each other
> - Applying FlowControl does not solve this for VMs on the same
> Hypervisor (as they're directly communicating, and traffic does not
> seem to go through the host)
> - Only security groups can prevent such communication, but since it's
> associated to a Port, we cannot enforce it
> - All flow control for the various networks connected to a VM are
> currently
> setup on a single bridge interface on the hypervisor
>
> First question is simple:
> Did we miss anything ? Or is our understanding of the mechanisms on point ?
>
> In the second case, this leads me to the proposal mentioned in the subject:
> Offer a Network/SecurityGroup binding mechanism that would
> automatically/implicitly include its rules to the port's rules.
>
> The idea is that this would allow an administrator (and project
> administrator?)
> to enforce specific rules via security groups attached to the network
> itself,
> effectively providing a category of network aimed at providing connectivity
> to a specific external service.
> Additionally, this creates a behavior where unless the administrator allows
> it,
> no two VMs on this network may be able to communicate together, as a
> default.
The way how security groups currently works is that You can specify what kind of traffic is allowed. You can't specify explicilty what is forbidden so even if you would have such additional security group attached to the network and through that effectively to all ports in that network, user would be able to add his own security group to the port and allow traffic which Your "network SG" did not allow.
>
> What do you think about this feature ?
> Is there any major risk/flaw that I might be missing ?
> Would you, as a community, welcome such an effort ?
I'm not saying I am against such idea but I think this will require very detailed spec with consideration of various corner cases and may be really complicated to do with how currently Neutron has implemented SG in general.
I think You should propose RFE: https://docs.openstack.org/neutron/latest/contributor/policies/blueprints.html#neutron-request-for-feature-enhancements and it will be then discussed in one of the neutron drivers team meetings. That should be first step for You.
>
> Kind regards,
>
> --
> David Pineau
> Engineer @Shadow
> IRC nick: joa
>
--
Slawek Kaplonski
Principal Software Engineer
Red Hat