Restrict Binding to Cluster-Admin

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: restrict-binding-clusteradmin
  annotations:
    policies.kyverno.io/title: Restrict Binding to Cluster-Admin
    policies.kyverno.io/category: Security
    policies.kyverno.io/severity: medium
    policies.kyverno.io/subject: RoleBinding, ClusterRoleBinding, RBAC
    kyverno.io/kyverno-version: 1.6.2
    policies.kyverno.io/minversion: 1.6.0
    kyverno.io/kubernetes-version: "1.23"
    policies.kyverno.io/description: The cluster-admin ClusterRole allows any action to be performed on any resource in the cluster and its granting should be heavily restricted. This policy prevents binding to the cluster-admin ClusterRole in RoleBinding or ClusterRoleBinding resources.
spec:
  validationFailureAction: Audit
  background: true
  rules:
    - name: clusteradmin-bindings
      match:
        any:
          - resources:
              kinds:
                - RoleBinding
                - ClusterRoleBinding
      validate:
        message: Binding to cluster-admin is not allowed.
        pattern:
          roleRef:
            name: "!cluster-admin"