Configuring a Pod Security Policy
A pod security policy (PSP) is a cluster-level resource that controls sensitive security aspects of the pod specification. The PodSecurityPolicy object in Kubernetes defines a group of conditions that a pod must comply with to be accepted by the system, as well as the default values of related fields.
By default, the PSP access control component is enabled for clusters of v1.17.17 and a global default PSP named psp-global is created. You can modify the default policy (but not delete it). You can also create a PSP and bind it to the RBAC configuration.
- In addition to the global default PSP, the system configures independent PSPs for system components in namespace kube-system. Modifying the psp-global configuration does not affect pod creation in namespace kube-system.
- PodSecurityPolicy was deprecated in Kubernetes v1.21, and removed from Kubernetes in v1.25. You can use pod security admission as a substitute for PodSecurityPolicy. For details, see Configuring Pod Security Admission.
Modifying the Global Default PSP
Before modifying the global default PSP, ensure that a CCE cluster has been created and connected by using kubectl.
- Run the following command:
kubectl edit psp psp-global
- Modify the required parameters, as shown in Table 1.
Table 1 PSP configuration Item
Description
privileged
Starts the privileged container.
hostPID
hostIPC
Uses the host namespace.
hostNetwork
hostPorts
Uses the host network and port.
volumes
Specifies the type of the mounted volume that can be used.
allowedHostPaths
Specifies the host path to which a hostPath volume can be mounted. The pathPrefix field specifies the host path prefix group to which a hostPath volume can be mounted.
allowedFlexVolumes
Specifies the FlexVolume driver that can be used.
fsGroup
Configures the supplemental group ID used by the mounted volume in the pod.
readOnlyRootFilesystem
Pods can only be started using a read-only root file system.
runAsUser
runAsGroup
supplementalGroups
Specifies the user ID, primary group ID, and supplemental group ID for starting containers in a pod.
allowPrivilegeEscalation
defaultAllowPrivilegeEscalation
Specifies whether allowPrivilegeEscalation can be set to true in a pod. This configuration controls the use of Setuid and whether programs can use additional privileged system calls.
defaultAddCapabilities
requiredDropCapabilities
allowedCapabilities
Controls the Linux capabilities used in pods.
seLinux
Controls the configuration of seLinux used in pods.
allowedProcMountTypes
Controls the ProcMountTypes that can be used by pods.
annotations
Configures AppArmor or Seccomp used by containers in a pod.
forbiddenSysctls
allowedUnsafeSysctls
Controls the configuration of Sysctl used by containers in a pod.
Example of Enabling Unsafe Sysctls in Pod Security Policy
You can configure allowed-unsafe-sysctls for a node pool. For CCE clusters of v1.17.17 and later versions, add configurations in allowedUnsafeSysctls of the pod security policy to make the configuration take effect. For details, see Table 1.
In addition to modifying the global pod security policy, you can add new pod security policies. For example, enable the net.core.somaxconn unsafe sysctls. The following is an example of adding a pod security policy:
apiVersion: policy/v1beta1 kind: PodSecurityPolicy metadata: annotations: seccomp.security.alpha.kubernetes.io/allowedProfileNames: '*' name: sysctl-psp spec: allowedUnsafeSysctls: - net.core.somaxconn allowPrivilegeEscalation: true allowedCapabilities: - '*' fsGroup: rule: RunAsAny hostIPC: true hostNetwork: true hostPID: true hostPorts: - max: 65535 min: 0 privileged: true runAsGroup: rule: RunAsAny runAsUser: rule: RunAsAny seLinux: rule: RunAsAny supplementalGroups: rule: RunAsAny volumes: - '*' --- kind: ClusterRole apiVersion: rbac.authorization.k8s.io/v1 metadata: name: sysctl-psp rules: - apiGroups: - "*" resources: - podsecuritypolicies resourceNames: - sysctl-psp verbs: - use --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: sysctl-psp roleRef: kind: ClusterRole name: sysctl-psp apiGroup: rbac.authorization.k8s.io subjects: - kind: Group name: system:authenticated apiGroup: rbac.authorization.k8s.io
Restoring the Original PSP
If you have modified the default pod security policy and want to restore the original pod security policy, perform the following operations.
- Create a policy description file named policy.yaml. policy.yaml is an example file name. You can rename it as required.
vi policy.yaml
The content of the description file is as follows:
apiVersion: policy/v1beta1 kind: PodSecurityPolicy metadata: name: psp-global annotations: seccomp.security.alpha.kubernetes.io/allowedProfileNames: '*' spec: privileged: true allowPrivilegeEscalation: true allowedCapabilities: - '*' volumes: - '*' hostNetwork: true hostPorts: - min: 0 max: 65535 hostIPC: true hostPID: true runAsUser: rule: 'RunAsAny' seLinux: rule: 'RunAsAny' supplementalGroups: rule: 'RunAsAny' fsGroup: rule: 'RunAsAny' --- kind: ClusterRole apiVersion: rbac.authorization.k8s.io/v1 metadata: name: psp-global rules: - apiGroups: - "*" resources: - podsecuritypolicies resourceNames: - psp-global verbs: - use --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: psp-global roleRef: kind: ClusterRole name: psp-global apiGroup: rbac.authorization.k8s.io subjects: - kind: Group name: system:authenticated apiGroup: rbac.authorization.k8s.io
- Run the following command:
kubectl apply -f policy.yaml
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