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</> ValidatingAdmissionPolicy · Apache-2.0

Mounts a hostPath Volume From the Node

pod-hostpath-volumes

severityCritical resourcePods productKubernetes bundles2

A hostPath volume mounts node filesystem paths into the pod, exposing kubelet credentials, container runtime sockets and other workload data, and a writable mount lets an attacker alter node files to take over the node.

Rejects unless

!has(object.spec.volumes) || object.spec.volumes.all(v, !has(v.hostPath))

HostPath volumes are disallowed. Each spec.volumes[*].hostPath must be undefined.

Remediation

Remove the hostPath volume and use an emptyDir, ConfigMap or PersistentVolumeClaim instead. Field: spec.volumes[*].hostPath.

Applies to

  • pods · v1 · CREATE, UPDATE

Manifest

apiVersion: admissionregistration.k8s.io/v1
kind: ValidatingAdmissionPolicy
metadata:
  name: pod-hostpath-volumes
  annotations:
    kubeapt.io/uuid: "5612ded8-9174-42bf-80de-52468a236655"
    security.kubeapt.io/displayName: "Mounts a hostPath Volume From the Node"
    security.kubeapt.io/description: "A hostPath volume mounts node filesystem paths into the pod, exposing kubelet credentials, container runtime sockets and other workload data, and a writable mount lets an attacker alter node files to take over the node."
    security.kubeapt.io/resource: "Pods"
    security.kubeapt.io/severity: "Critical"
    security.kubeapt.io/remediation: "Remove the hostPath volume and use an emptyDir, ConfigMap or PersistentVolumeClaim instead. Field: spec.volumes[*].hostPath."
    security.kubeapt.io/product: "Kubernetes"
spec:
  failurePolicy: Fail
  matchConstraints:
    resourceRules:
    - apiGroups:
      - ''
      apiVersions:
      - v1
      operations:
      - CREATE
      - UPDATE
      resources:
      - pods
  validations:
  - expression: |
      !has(object.spec.volumes) || object.spec.volumes.all(v, !has(v.hostPath))
    message: |
      HostPath volumes are disallowed. Each spec.volumes[*].hostPath must be undefined.

Save it as pod-hostpath-volumes.yaml — the commands below assume that name.

Validate with kubeapt

Check a workload against this one policy, before anything is installed on a cluster.

$ kubeapt validate -p ./pod-hostpath-volumes.yaml -r ./workload.yaml

Or without the file, from the published policy set — -r takes a directory too:

$ kubeapt policies download && kubeapt validate --policy-name pod-hostpath-volumes -r ./manifests

Or against every namespace in the cluster your kubeconfig points at:

$ kubeapt validate --policy-name pod-hostpath-volumes -A

Bundles

Source

View policy.yaml on GitHub →