Drop CAP_NET_RAW

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: drop-cap-net-raw
  annotations:
    policies.kyverno.io/title: Drop CAP_NET_RAW
    policies.kyverno.io/category: Best Practices
    policies.kyverno.io/minversion: 1.6.0
    policies.kyverno.io/severity: medium
    policies.kyverno.io/subject: Pod
    policies.kyverno.io/description: Capabilities permit privileged actions without giving full root access. The CAP_NET_RAW capability, enabled by default, allows processes in a container to forge packets and bind to any interface potentially leading to MitM attacks. This policy ensures that all containers explicitly drop the CAP_NET_RAW ability. Note that this policy also illustrates how to cover drop entries in any case although this may not strictly conform to the Pod Security Standards.
spec:
  validationFailureAction: Audit
  background: true
  rules:
    - name: require-drop-cap-net-raw
      match:
        any:
          - resources:
              kinds:
                - Pod
      preconditions:
        all:
          - key: "{{ request.operation || 'BACKGROUND' }}"
            operator: NotEquals
            value: DELETE
      validate:
        message: Containers must drop the `CAP_NET_RAW` capability.
        foreach:
          - list: request.object.spec.[ephemeralContainers, initContainers, containers][]
            deny:
              conditions:
                all:
                  - key: CAP_NET_RAW
                    operator: AnyNotIn
                    value: "{{ element.securityContext.capabilities.drop[].to_upper(@) || `[]` }}"
                  - key: NET_RAW
                    operator: AnyNotIn
                    value: "{{ element.securityContext.capabilities.drop[].to_upper(@) || `[]` }}"