--- approvers: - pweil- title: Pod Security Policies --- Objects of type `PodSecurityPolicy` govern the ability to make requests on a pod that affect the `SecurityContext` that will be applied to a pod and container. See [PodSecurityPolicy proposal](https://git.k8s.io/community/contributors/design-proposals/auth/pod-security-policy.md) for more information. * TOC {:toc} ## What is a Pod Security Policy? A _Pod Security Policy_ is a cluster-level resource that controls the actions that a pod can perform and what it has the ability to access. The `PodSecurityPolicy` objects define a set of conditions that a pod must run with in order to be accepted into the system. They allow an administrator to control the following: | Control Aspect | Field Name | | ------------------------------------------------------------- | --------------------------------- | | Running of privileged containers | `privileged` | | Default set of capabilities that will be added to a container | `defaultAddCapabilities` | | Capabilities that will be dropped from a container | `requiredDropCapabilities` | | Capabilities a container can request to be added | `allowedCapabilities` | | Controlling the usage of volume types | [`volumes`](#controlling-volumes) | | The use of host networking | [`hostNetwork`](#host-network) | | The use of host ports | `hostPorts` | | The use of host's PID namespace | `hostPID` | | The use of host's IPC namespace | `hostIPC` | | The SELinux context of the container | [`seLinux`](#selinux) | | The user ID | [`runAsUser`](#runasuser) | | Configuring allowable supplemental groups | [`supplementalGroups`](#supplementalgroups) | | Allocating an FSGroup that owns the pod's volumes | [`fsGroup`](#fsgroup) | | Requiring the use of a read only root file system | `readOnlyRootFilesystem` | _Pod Security Policies_ are comprised of settings and strategies that control the security features a pod has access to. These settings fall into three categories: - *Controlled by a Boolean*: Fields of this type default to the most restrictive value. - *Controlled by an allowable set*: Fields of this type are checked against the set to ensure their values are allowed. - *Controlled by a strategy*: Items that have a strategy to provide a mechanism to generate the value and a mechanism to ensure that a specified value falls into the set of allowable values. ## Strategies ### RunAsUser - *MustRunAs* - Requires a `range` to be configured. Uses the first value of the range as the default. Validates against the configured range. - *MustRunAsNonRoot* - Requires that the pod be submitted with a non-zero `runAsUser` or have the `USER` directive defined in the image. No default provided. - *RunAsAny* - No default provided. Allows any `runAsUser` to be specified. ### SELinux - *MustRunAs* - Requires `seLinuxOptions` to be configured if not using pre-allocated values. Uses `seLinuxOptions` as the default. Validates against `seLinuxOptions`. - *RunAsAny* - No default provided. Allows any `seLinuxOptions` to be specified. ### SupplementalGroups - *MustRunAs* - Requires at least one range to be specified. Uses the minimum value of the first range as the default. Validates against all ranges. - *RunAsAny* - No default provided. Allows any `supplementalGroups` to be specified. ### FSGroup - *MustRunAs* - Requires at least one range to be specified. Uses the minimum value of the first range as the default. Validates against the first ID in the first range. - *RunAsAny* - No default provided. Allows any `fsGroup` ID to be specified. ### Controlling Volumes The usage of specific volume types can be controlled by setting the volumes field of the PSP. The allowable values of this field correspond to the volume sources that are defined when creating a volume: 1. azureFile 1. azureDisk 1. flocker 1. flexVolume 1. hostPath 1. emptyDir 1. gcePersistentDisk 1. awsElasticBlockStore 1. gitRepo 1. secret 1. nfs 1. iscsi 1. glusterfs 1. persistentVolumeClaim 1. rbd 1. cinder 1. cephFS 1. downwardAPI 1. fc 1. configMap 1. vsphereVolume 1. quobyte 1. photonPersistentDisk 1. projected 1. portworxVolume 1. scaleIO 1. storageos 1. \* (allow all volumes) The recommended minimum set of allowed volumes for new PSPs are configMap, downwardAPI, emptyDir, persistentVolumeClaim, secret, and projected. ### Host Network - *HostPorts*, default `empty`. List of `HostPortRange`, defined by `min`(inclusive) and `max`(inclusive), which define the allowed host ports. ## Admission _Admission control_ with `PodSecurityPolicy` allows for control over the creation and modification of resources based on the capabilities allowed in the cluster. Admission uses the following approach to create the final security context for the pod: 1. Retrieve all PSPs available for use. 1. Generate field values for security context settings that were not specified on the request. 1. Validate the final settings against the available policies. If a matching policy is found, then the pod is accepted. If the request cannot be matched to a PSP, the pod is rejected. A pod must validate every field against the PSP. ## Creating a Pod Security Policy Here is an example Pod Security Policy. It has permissive settings for all fields {% include code.html language="yaml" file="psp.yaml" ghlink="/docs/concepts/policy/psp.yaml" %} Create the policy by downloading the example file and then running this command: ```shell $ kubectl create -f ./psp.yaml podsecuritypolicy "permissive" created ``` ## Getting a list of Pod Security Policies To get a list of existing policies, use `kubectl get`: ```shell $ kubectl get psp NAME PRIV CAPS SELINUX RUNASUSER FSGROUP SUPGROUP READONLYROOTFS VOLUMES permissive false [] RunAsAny RunAsAny RunAsAny RunAsAny false [*] privileged true [] RunAsAny RunAsAny RunAsAny RunAsAny false [*] restricted false [] RunAsAny MustRunAsNonRoot RunAsAny RunAsAny false [emptyDir secret downwardAPI configMap persistentVolumeClaim projected] ``` ## Editing a Pod Security Policy To modify policy interactively, use `kubectl edit`: ```shell $ kubectl edit psp permissive ``` This command will open a default text editor where you will be able to modify policy. ## Deleting a Pod Security Policy Once you don't need a policy anymore, simply delete it with `kubectl`: ```shell $ kubectl delete psp permissive podsecuritypolicy "permissive" deleted ``` ## Enabling Pod Security Policies In order to use Pod Security Policies in your cluster you must ensure the following 1. You have enabled the API type `extensions/v1beta1/podsecuritypolicy` (only for versions prior 1.6) 1. You have enabled the admission controller `PodSecurityPolicy` 1. You have defined your policies ## Working With RBAC In Kubernetes 1.5 and newer, you can use PodSecurityPolicy to control access to privileged containers based on user role and groups. Access to different PodSecurityPolicy objects can be controlled via authorization. Note that [Controller Manager](/docs/admin/kube-controller-manager/) must be run against [the secured API port](/docs/admin/accessing-the-api/), and must not have superuser permissions. Otherwise requests would bypass authentication and authorization modules, all PodSecurityPolicy objects would be allowed, and user will be able to create privileged containers. PodSecurityPolicy authorization uses the union of all policies available to the user creating the pod and [the service account specified on the pod](/docs/tasks/configure-pod-container/configure-service-account/). Access to given PSP policies for a user will be effective only when creating Pods directly. For pods created on behalf of a user, in most cases by Controller Manager, access should be given to the service account specified on the pod spec template. Examples of resources that create pods on behalf of a user are Deployments, ReplicaSets, etc. For more details, see the [PodSecurityPolicy RBAC example](https://git.k8s.io/examples/staging/podsecuritypolicy/rbac/README.md) of applying PodSecurityPolicy to control access to privileged containers based on role and groups when deploying Pods directly.