Use Pod Security Policy constraints

Policy Controller comes with a default library of constraint templates that can be used with the Pod Security Policy bundle to achieve many of the same protections as Kubernetes Pod Security Policy (PSP), with the added ability to test your policies before enforcing them and exclude coverage of specific resources.

This page contains instructions for manually applying a policy bundle. Alternatively, you can apply policy bundles directly.

Warning: After you choose a method to apply policy bundles (manual, gcloud CLI, or Google Cloud console), using a different method to install policy bundles can cause errors in your environment.

This page is for IT administrators and Operators who want to ensure that all resources running within the cloud platform meet organizational compliance requirements by providing and maintaining automation to audit or enforce. To learn more about common roles and example tasks that we reference in Google Cloud content, see Common GKE Enterprise user roles and tasks.

The bundle includes these constraints which provide parameters which map to the following Kubernetes Pod Security Policy (PSP) Field Names (Control IDs):

Constraint Name	Constraint Description	Control ID
psp-v2022-psp-allow-privilege-escalation	Restricting escalation to root privileges	allowPrivilegeEscalation
psp-v2022-psp-apparmor	The AppArmor profile used by containers	annotations
psp-v2022-psp-capabilities	Linux capabilities	allowedCapabilities, requiredDropCapabilities
psp-v2022-flexvolume-drivers	Allow specific FlexVolume drivers	allowedFlexVolumes
psp-v2022-psp-forbidden-sysctls	The sysctl profile used by containers	forbiddenSysctls
psp-v2022-psp-fsgroup	Allocating an FSGroup that owns the pod's volumes	fsGroup
psp-v2022-psp-host-filesystem	Usage of the host filesystem	allowedHostPaths
psp-v2022-psp-host-namespace	Usage of host namespaces	hostPID, hostIPC
psp-v2022-psp-host-network-ports	Usage of host networking and ports	hostNetwork, hostPorts
psp-v2022-psp-privileged-container	Running of privileged containers	privileged
psp-v2022-psp-proc-mount	The Allowed Proc Mount types for the container	allowedProcMountTypes
psp-v2022-psp-readonlyrootfilesystem	Requiring the use of a read-only root file system	readOnlyRootFilesystem
psp-v2022-psp-seccomp	The seccomp profile used by containers	annotations
psp-v2022-psp-selinux-v2	The SELinux context of the container	seLinux
psp-v2022-psp-pods-allowed-user-ranges	The user and group IDs of the container	runAsUser, runAsGroup, supplementalGroups, fsGroup
psp-v2022-psp-volume-types	Usage of volume types	volumes

Before you begin

1. Install and initialize the Google Cloud CLI, which provides the gcloud and kubectl commands used in these instructions. If you use Cloud Shell, Google Cloud CLI comes pre-installed.
2. Install Policy Controller on your cluster with the default library of constraint templates.

Audit Pod Security Policy policy bundle

Policy Controller lets you enforce policies for your Kubernetes cluster. To help test your workloads and their compliance with regard to the Google recommended best practices outlined in the preceding table, you can deploy these constraints in "audit" mode to reveal violations and more importantly give yourself a chance to fix them before enforcing on your Kubernetes cluster.

You can apply these policies with spec.enforcementAction set to dryrun using kubectl, kpt, or Config Sync.

kubectl

1. (Optional) Preview the policy constraints with kubectl:

   kubectl kustomize https://github.com/GoogleCloudPlatform/gke-policy-library.git/bundles/psp-v2022
   

2. Apply the policy constraints with kubectl:

   kubectl apply -k https://github.com/GoogleCloudPlatform/gke-policy-library.git/bundles/psp-v2022
   

   The output is the following:

   k8spspallowprivilegeescalationcontainer.constraints.gatekeeper.sh/psp-v2022-psp-allow-privilege-escalation created
   k8spspallowedusers.constraints.gatekeeper.sh/psp-v2022-psp-pods-allowed-user-ranges created
   k8spspapparmor.constraints.gatekeeper.sh/psp-v2022-psp-apparmor created
   k8spspcapabilities.constraints.gatekeeper.sh/psp-v2022-psp-capabilities created
   k8spspfsgroup.constraints.gatekeeper.sh/psp-v2022-psp-fsgroup created
   k8spspflexvolumes.constraints.gatekeeper.sh/psp-v2022-psp-flexvolume-drivers created
   k8spspforbiddensysctls.constraints.gatekeeper.sh/psp-v2022-psp-forbidden-sysctls created
   k8spsphostfilesystem.constraints.gatekeeper.sh/psp-v2022-psp-host-filesystem created
   k8spsphostnamespace.constraints.gatekeeper.sh/psp-v2022-psp-host-namespace created
   k8spsphostnetworkingports.constraints.gatekeeper.sh/psp-v2022-psp-host-network-ports created
   k8spspprivilegedcontainer.constraints.gatekeeper.sh/psp-v2022-psp-privileged-container created
   k8spspprocmount.constraints.gatekeeper.sh/psp-v2022-psp-proc-mount created
   k8spspreadonlyrootfilesystem.constraints.gatekeeper.sh/psp-v2022-psp-readonlyrootfilesystem created
   k8spspselinuxv2.constraints.gatekeeper.sh/psp-v2022-psp-selinux-v2 created
   k8spspseccomp.constraints.gatekeeper.sh/psp-v2022-psp-seccomp created
   k8spspvolumetypes.constraints.gatekeeper.sh/psp-v2022-psp-volume-types created
   

3. Verify that policy constraints have been installed and check if violations exist across the cluster:

   kubectl get -k https://github.com/GoogleCloudPlatform/gke-policy-library.git/bundles/psp-v2022
   

   The output is similar to the following:

   NAME                                                                                                         ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspallowprivilegeescalationcontainer.constraints.gatekeeper.sh/psp-v2022-psp-allow-privilege-escalation   dryrun               0
   
   NAME                                                                                  ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspallowedusers.constraints.gatekeeper.sh/psp-v2022-psp-pods-allowed-user-ranges   dryrun               0
   
   NAME                                                              ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspapparmor.constraints.gatekeeper.sh/psp-v2022-psp-apparmor                        0
   
   NAME                                                                      ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspcapabilities.constraints.gatekeeper.sh/psp-v2022-psp-capabilities   dryrun               0
   
   NAME                                                            ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspfsgroup.constraints.gatekeeper.sh/psp-v2022-psp-fsgroup                        0
   
   NAME                                                                           ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspflexvolumes.constraints.gatekeeper.sh/psp-v2022-psp-flexvolume-drivers                        0
   
   NAME                                                                               ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspforbiddensysctls.constraints.gatekeeper.sh/psp-v2022-psp-forbidden-sysctls                        0
   
   NAME                                                                           ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spsphostfilesystem.constraints.gatekeeper.sh/psp-v2022-psp-host-filesystem                        0
   
   NAME                                                                         ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spsphostnamespace.constraints.gatekeeper.sh/psp-v2022-psp-host-namespace   dryrun               0
   
   NAME                                                                                   ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spsphostnetworkingports.constraints.gatekeeper.sh/psp-v2022-psp-host-network-ports   dryrun               0
   
   NAME                                                                                     ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspprivilegedcontainer.constraints.gatekeeper.sh/psp-v2022-psp-privileged-container   dryrun               0
   
   NAME                                                                 ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspprocmount.constraints.gatekeeper.sh/psp-v2022-psp-proc-mount                        0
   
   NAME                                                                                          ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspreadonlyrootfilesystem.constraints.gatekeeper.sh/psp-v2022-psp-readonlyrootfilesystem                        0
   
   NAME                                                                 ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspselinuxv2.constraints.gatekeeper.sh/psp-v2022-psp-selinux-v2                        0
   
   NAME                                                            ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspseccomp.constraints.gatekeeper.sh/psp-v2022-psp-seccomp   dryrun               0
   
   NAME                                                                     ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspvolumetypes.constraints.gatekeeper.sh/psp-v2022-psp-volume-types                        0
   

4. (Optional) Adjust the PSP Field Name parameters in the constraint files as required for your cluster environment. For more details check the link for the specific PSP Field Name in the table above. For example in psp-host-network-ports:

   parameters:
     hostNetwork: true
     min: 80
     max: 9000
   

kpt

1. Install and setup kpt. kpt is used in these instructions to customize and deploy Kubernetes resources.

2. Download the Pod Security Policy (PSP) v2022 policy bundle from GitHub using kpt:

   kpt pkg get https://github.com/GoogleCloudPlatform/gke-policy-library.git/bundles/psp-v2022
   

3. Run the set-enforcement-action kpt function to set the policies' enforcement action to dryrun:

   kpt fn eval psp-v2022 -i gcr.io/kpt-fn/set-enforcement-action:v0.1 \
     -- enforcementAction=dryrun
   

4. Initialize the working directory with kpt, which creates a resource to track changes:

   cd psp-v2022
   kpt live init
   

5. (Optional) Adjust the PSP Field Name parameters in the constraint files as required for your cluster environment. For more details check the link for the specific PSP Field Name in the table above. For example in psp-host-network-ports:

   parameters:
     hostNetwork: true
     min: 80
     max: 9000
   

6. Apply the policy constraints with kpt:

   kpt live apply
   

7. Verify that policy constraints have been installed and check if violations exist across the cluster:

   kpt live status --output table --poll-until current
   

   A status of CURRENT confirms successful installation of the constraints.

Config Sync

1. Install and setup kpt. kpt is used in these instructions to customize and deploy Kubernetes resources.

Operators using Config Sync to deploy policies to their clusters can use the following instructions:

1. Change into the sync directory for Config Sync:

   cd SYNC_ROOT_DIR
   

   Note: Kpt v1.0.0-beta.17 and later automatically create a resourcegroup.yaml file during live init which shouldn't be checked into your Config Sync repo. If not already present, add resourcegroup.yaml to your repo's .gitignore file.

   To create or append .gitignore with resourcegroup.yaml:

   echo resourcegroup.yaml >> .gitignore
   

2. Create a dedicated policies directory:

   mkdir -p policies
   

3. Download the Pod Security Policy (PSP) v2022 policy bundle from GitHub using kpt:

   kpt pkg get https://github.com/GoogleCloudPlatform/gke-policy-library.git/bundles/psp-v2022 policies/psp-v2022
   

4. Run the set-enforcement-action kpt function to set the policies' enforcement action to dryrun:

   kpt fn eval policies/psp-v2022 -i gcr.io/kpt-fn/set-enforcement-action:v0.1 -- enforcementAction=dryrun
   

5. (Optional) Adjust the PSP Field Name parameters in the constraint files as required for your cluster environment. For more details check the link for the specific PSP Field Name in the table above. For example in psp-host-network-ports:

   parameters:
     hostNetwork: true
     min: 80
     max: 9000
   

6. (Optional) Preview the policy constraints to be created:

   kpt live init policies/psp-v2022
   kpt live apply --dry-run policies/psp-v2022
   

   The output is the following:

   Dry-run strategy: client
   inventory update started
   inventory update finished
   apply phase started
   k8spspallowprivilegeescalationcontainer.constraints.gatekeeper.sh/psp-v2022-psp-allow-privilege-escalation apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspallowedusers.constraints.gatekeeper.sh/psp-v2022-psp-pods-allowed-user-ranges apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspapparmor.constraints.gatekeeper.sh/psp-v2022-psp-apparmor apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspcapabilities.constraints.gatekeeper.sh/psp-v2022-psp-capabilities apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspfsgroup.constraints.gatekeeper.sh/psp-v2022-psp-fsgroup apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspflexvolumes.constraints.gatekeeper.sh/psp-v2022-psp-flexvolume-drivers apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspforbiddensysctls.constraints.gatekeeper.sh/psp-v2022-psp-forbidden-sysctls apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spsphostfilesystem.constraints.gatekeeper.sh/psp-v2022-psp-host-filesystem apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spsphostnamespace.constraints.gatekeeper.sh/psp-v2022-psp-host-namespace apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spsphostnetworkingports.constraints.gatekeeper.sh/psp-v2022-psp-host-network-ports apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspprivilegedcontainer.constraints.gatekeeper.sh/psp-v2022-psp-privileged-container apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspprocmount.constraints.gatekeeper.sh/psp-v2022-psp-proc-mount apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspreadonlyrootfilesystem.constraints.gatekeeper.sh/psp-v2022-psp-readonlyrootfilesystem apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspselinuxv2.constraints.gatekeeper.sh/psp-v2022-psp-selinux-v2 apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspseccomp.constraints.gatekeeper.sh/psp-v2022-psp-seccomp apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   k8spspvolumetypes.constraints.gatekeeper.sh/psp-v2022-psp-volume-types apply skipped: inventory policy prevented actuation (strategy: Apply, status: Empty, policy: MustMatch)
   apply phase finished
   inventory update started
   inventory update finished
   apply result: 16 attempted, 0 successful, 16 skipped, 0 failed
   

7. If your sync directory for Config Sync uses Kustomize, add policies/psp-v2022 to your root kustomization.yaml. Otherwise remove the policies/psp-v2022/kustomization.yaml file:

   rm SYNC_ROOT_DIR/policies/psp-v2022/kustomization.yaml
   

8. Push changes to the Config Sync repo:

   git add SYNC_ROOT_DIR/policies/psp-v2022
   git commit -m 'Adding Pod Security Policy audit enforcement'
   git push
   

9. Verify the status of the installation:

   watch gcloud beta container fleet config-management status --project PROJECT_ID
   

   A status of SYNCED confirms the installation of the policies.

View policy violations

Once the policy constraints are installed in audit mode, violations on the cluster can be viewed in the UI using the Policy Controller Dashboard.

You can also use kubectl to view violations on the cluster using the following command:

kubectl get constraint -l policycontroller.gke.io/bundleName=psp-v2022 -o json | jq -cC '.items[]| [.metadata.name,.status.totalViolations]'

If violations are present, a listing of the violation messages per constraint can be viewed with:

kubectl get constraint -l policycontroller.gke.io/bundleName=psp-v2022 -o json | jq -C '.items[]| select(.status.totalViolations>0)| [.metadata.name,.status.violations[]?]'

Change Pod Security Policy policy bundle enforcement action

Once you've reviewed policy violations on your cluster, you can consider changing the enforcement mode so the Admission Controller will either warn on or even deny block non-compliant resource from getting applied to the cluster.

Warning: The deny enforcement action should be used with care as it can potentially block required changes resulting in interruption to critical workloads or the cluster. It is strongly recommended that only the warn or dryrun enforcement actions are used on clusters with production workloads, when testing new constraints, or performing migrations such as upgrading platforms. For more information about enforcement actions, see Auditing using constraints.

kubectl

1. Use kubectl to set the policies' enforcement action to warn:

   kubectl get constraint -l policycontroller.gke.io/bundleName=psp-v2022 -o name | xargs -I {} kubectl patch {} --type='json' -p='[{"op":"replace","path":"/spec/enforcementAction","value":"warn"}]'
   

2. Verify that policy constraints enforcement action have been updated:

   kubectl get constraint -l policycontroller.gke.io/bundleName=psp-v2022
   

kpt

1. Run the set-enforcement-action kpt function to set the policies' enforcement action to warn:

   kpt fn eval -i gcr.io/kpt-fn/set-enforcement-action:v0.1 -- enforcementAction=warn
   

2. Apply the policy constraints:

   kpt live apply
   

Config Sync

Operators using Config Sync to deploy policies to their clusters can use the following instructions:

1. Change into the sync directory for Config Sync:

   cd SYNC_ROOT_DIR
   

2. Run the set-enforcement-action kpt function to set the policies' enforcement action to warn:

   kpt fn eval policies/psp-v2022 -i gcr.io/kpt-fn/set-enforcement-action:v0.1 -- enforcementAction=warn
   

3. Push changes to the Config Sync repo:

   git add SYNC_ROOT_DIR/policies/psp-v2022
   git commit -m 'Adding Pod Security Policy policy bundle warn enforcement'
   git push
   

4. Verify the status of the installation:

   gcloud alpha anthos config sync repo list --project PROJECT_ID
   

   Your repo showing up in the SYNCED column confirms the installation of the policies.

Test policy enforcement

Create a non-compliant resource on the cluster using the following command:

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  namespace: default
  name: wp-non-compliant
  labels:
    app: wordpress
spec:
  containers:
    - image: wordpress
      name: wordpress
      ports:
      - containerPort: 80
        name: wordpress
EOF

The admission controller should produce a warning listing out the policy violations that this resource violates, as shown in the following example:

Warning: [psp-v2022-psp-pods-allowed-user-ranges] Container wordpress is attempting to run without a required securityContext/fsGroup. Allowed fsGroup: {"ranges": [{"max": 200, "min": 100}], "rule": "MustRunAs"}
Warning: [psp-v2022-psp-pods-allowed-user-ranges] Container wordpress is attempting to run without a required securityContext/runAsGroup. Allowed runAsGroup: {"ranges": [{"max": 200, "min": 100}], "rule": "MustRunAs"}
Warning: [psp-v2022-psp-pods-allowed-user-ranges] Container wordpress is attempting to run without a required securityContext/runAsUser
Warning: [psp-v2022-psp-pods-allowed-user-ranges] Container wordpress is attempting to run without a required securityContext/supplementalGroups. Allowed supplementalGroups: {"ranges": [{"max": 200, "min": 100}], "rule": "MustRunAs"}
Warning: [psp-v2022-psp-allow-privilege-escalation] Privilege escalation container is not allowed: wordpress
Warning: [psp-v2022-psp-seccomp] Seccomp profile 'not configured' is not allowed for container 'wordpress'. Found at: no explicit profile found. Allowed profiles: {"RuntimeDefault", "docker/default", "runtime/default"}
Warning: [psp-v2022-psp-capabilities] container <wordpress> is not dropping all required capabilities. Container must drop all of ["must_drop"] or "ALL"
Warning: [psp-v2022-psp-readonlyrootfilesystem] only read-only root filesystem container is allowed: wordpress
pod/wp-non-compliant created

Remove Pod Security Policy policy bundle

If needed, the Pod Security Policy policy bundle can be removed from the cluster.

kubectl

• Use kubectl to remove the policies:

  kubectl delete constraint -l policycontroller.gke.io/bundleName=psp-v2022
  

kpt

• Remove the policies:

  kpt live destroy
  

Config Sync

Operators using Config Sync to deploy policies to their clusters can use the following instructions:

1. Push changes to the Config Sync repo:

   git rm -r SYNC_ROOT_DIR/policies/psp-v2022
   git commit -m 'Removing PSP policies'
   git push
   

2. Verify the status:

   gcloud alpha anthos config sync repo list --project PROJECT_ID
   

   Your repo showing up in the SYNCED column confirms the removal of the policies.