policy-gatekeeper-allowed-external-ips.yaml

apiVersion: policy.open-cluster-management.io/v1
kind: Policy
metadata:
  name: policy-gatekeeper-allowed-external-ips
  annotations:
    policy.open-cluster-management.io/standards: NIST SP 800-53
    policy.open-cluster-management.io/categories: CM Configuration Management
    policy.open-cluster-management.io/controls: CM-2 Baseline Configuration
spec:
  disabled: false
  policy-templates:
    - objectDefinition:
        apiVersion: policy.open-cluster-management.io/v1
        kind: ConfigurationPolicy
        metadata:
          name: policy-gatekeeper-k8sexternalips
        spec:
          remediationAction: enforce # will be overridden by remediationAction in parent policy
          severity: low
          object-templates:
            - complianceType: musthave
              objectDefinition:
                apiVersion: templates.gatekeeper.sh/v1beta1
                kind: ConstraintTemplate
                metadata:
                  name: k8sexternalips
                spec:
                  crd:
                    spec:
                      names:
                        kind: K8sExternalIPs
                      validation:
                        # Schema for the `parameters` field
                        openAPIV3Schema:
                          properties:
                            allowedIPs:
                              type: array
                              items:
                                type: string
                  targets:
                    - target: admission.k8s.gatekeeper.sh
                      rego: |
                        package k8sexternalips

                        violation[{"msg": msg}] {
                          input.review.kind.kind == "Service"
                          input.review.kind.group == ""
                          allowedIPs := {ip | ip := input.parameters.allowedIPs[_]}
                          externalIPs := {ip | ip := input.review.object.spec.externalIPs[_]}
                          forbiddenIPs := externalIPs - allowedIPs
                          count(forbiddenIPs) > 0
                          msg := sprintf("service has forbidden external IPs: %v", [forbiddenIPs])
                        }
            - complianceType: musthave
              objectDefinition:
                apiVersion: constraints.gatekeeper.sh/v1beta1
                kind: K8sExternalIPs
                metadata:
                  name: external-ips
                spec:
                  enforcementAction: dryrun
                  match:
                    kinds:
                      - apiGroups: [""]
                        kinds: ["Service"]
                  parameters:
                    allowedIPs:
                      - "203.0.113.0"
    - objectDefinition:
        apiVersion: policy.open-cluster-management.io/v1
        kind: ConfigurationPolicy
        metadata:
          name: policy-gatekeeper-external-ips-audit
        spec:
          remediationAction: inform # will be overridden by remediationAction in parent policy
          severity: low
          object-templates:
            - complianceType: musthave
              objectDefinition:
                apiVersion: constraints.gatekeeper.sh/v1beta1
                kind: K8sExternalIPs
                metadata:
                  name: external-ips
                status:
                  totalViolations: 0
    - objectDefinition:
        apiVersion: policy.open-cluster-management.io/v1
        kind: ConfigurationPolicy
        metadata:
          name: policy-gatekeeper-external-ips-admission
        spec:
          remediationAction: inform # will be overridden by remediationAction in parent policy
          severity: low
          object-templates:
            - complianceType: mustnothave
              objectDefinition:
                apiVersion: v1
                kind: Event
                metadata:
                  namespace: openshift-gatekeeper-system # set it to the actual namespace where gatekeeper is running if different
                  annotations:
                    constraint_action: deny
                    constraint_kind: K8sExternalIPs
                    constraint_name: external-ips
                    event_type: violation