Bug 1764220

Description of problem: NetworkPolicies broken when dealing with hostNetwork

Following up on https://bugzilla.redhat.com/show_bug.cgi?id=1748034, as I'm still waiting for an answer

Version-Release number of selected component (if applicable): OCP 4.2
3.X affected as well.


How reproducible: Always


Steps to Reproduce:
1. Create an application Pod, with a Route
2. Apply a NetworkPolicy allowing traffic from ingress to application
3. Connect to the Route

Actual results: Traffic blocked


Expected results: Traffic allowed


Additional info:

According to the docs -- https://docs.openshift.com/container-platform/4.2/networking/configuring-networkpolicy.html#nw-networkpolicy-about_configuring-networkpolicy-plugin

I would need to create a NetworkPolicy matching some label on the openshift-ingress namespace

```
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-from-openshift-ingress
spec:
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          network.openshift.io/policy-group: ingress
  podSelector: {}
  policyTypes:
  - Ingress
```


Though this can not work.

Ingress Pods are using hostNetwork.

From OVS point of view, any Pod using hostNetwork would have its traffic considered to be part of netid0.

Hence, that NetworkPolicy actually blocks traffic from ingress to application Pods.