apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: restrict-image-registries
  annotations:
    policies.kyverno.io/title: Restrict image registries
    policies.kyverno.io/category: Supply chain
    policies.kyverno.io/severity: high
    # CIS 5.5.1: image provenance. This is a concrete admission control that
    # supports the broader provenance objective but is not the full CIS test.
    policies.kyverno.io/cis-control: "5.5.1 supplemental"
spec:
  validationFailureAction: Enforce
  background: false
  failurePolicy: Fail
  rules:
    - name: images-from-approved-registries
      match:
        any:
          - resources:
              kinds:
                - Pod
              namespaceSelector:
                matchLabels:
                  security-baseline/open: "true"
      validate:
        message: Images must come from ghcr.io, quay.io, or docker.io/library.
        foreach:
          - list: request.object.spec.containers[]
            anyPattern:
              - image: ghcr.io/*
              - image: quay.io/*
              - image: docker.io/library/*
          - list: request.object.spec.initContainers[]
            anyPattern:
              - image: ghcr.io/*
              - image: quay.io/*
              - image: docker.io/library/*