restrict-clusteradmin-rolebindings.yaml

# Copyright 2023 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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#
#      http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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apiVersion: constraints.gatekeeper.sh/v1beta1
kind: K8sRestrictRoleBindings
metadata:
  name: policy-essentials-v2022-restrict-clusteradmin-rolebindings
  labels:
    policycontroller.gke.io/bundleName: policy-essentials-v2022
  annotations:
    policycontroller.gke.io/constraintData: |
      "{
        bundleName: 'policy-essentials-v2022',
        bundleDisplayName: 'Policy Essentials v2022',
        bundleLink: 'https://github.com/GoogleCloudPlatform/acm-policy-controller-library/tree/master/bundles/policy-essentials-v2022',
        bundleVersion: '202301.0',
        bundleDescription: 'Use the Policy Essentials v2022 policy bundle with Anthos Policy Controller to apply Google recommended best practices to your cluster resources.',
        controlNumbers: '[]',
        severity: 'UNASSIGNED',
        description: 'Restricts the use of the `cluster-admin` role.',
        remediation: 'The use of the cluster-admin `ClusterRole` for Role-based access control (RBAC) is restricted. Use a different role. See “Using RBAC Authorization” for more information: https://kubernetes.io/docs/reference/access-authn-authz/rbac/#user-facing-roles',
        minimumTemplateLibraryVersion: '1.10.1'
      }"
spec:
  enforcementAction: dryrun
  parameters:
    restrictedRole:
      apiGroup: rbac.authorization.k8s.io
      kind: ClusterRole
      name: cluster-admin
    allowedSubjects:
    - apiGroup: rbac.authorization.k8s.io
      kind: Group
      name: system:masters
    # for GKE Hub feature authorizer
    - apiGroup: rbac.authorization.k8s.io
      kind: User
      name: ^service-[0-9]+@gcp-sa-gkehub.iam.gserviceaccount.com$
      regexMatch: true
    # for ACM to install in-cluster resources
    - apiGroup: rbac.authorization.k8s.io
      kind: User
      name: ^service-[0-9]+@gcp-sa-anthosconfigmanagement.iam.gserviceaccount.com$
      regexMatch: true
    # for Config Sync reconciler service account
    - kind: ServiceAccount
      name: reconciler-manager
    # For kube-storage-version-migrator, part of the GKE control plane
    - apiGroup: rbac.authorization.k8s.io
      kind: User
      name: system:storageversionmigrator
    # Kubernetes service account for Config Sync reconciler
    # https://cloud.google.com/anthos-config-management/docs/how-to/installing-config-sync#git-creds-secret
    - kind: ServiceAccount
      name: ^root-reconciler[a-z0-9-]*$
      regexMatch: true