kyverno/samples/DisallowBindMounts.md

Disallow use of bind mounts (hostPath volumes)

The volume of type hostPath allows pods to use host bind mounts (i.e. directories and volumes mounted to a host path) in containers. Using host resources can be used to access shared data or escalate priviliges. Also, this couples pods to a specific host and data persisted in the hostPath volume is coupled to the life of the node leading to potential pod scheduling failures. It is highly recommeded that applications are designed to be decoupled from the underlying infrstructure (in this case, nodes).

Policy YAML

disallow_bind_mounts.yaml

apiVersion: "kyverno.io/v1alpha1"
kind: "ClusterPolicy"
metadata: 
  name: "disallow-bind-mounts"
spec: 
  rules: 
  - name: "validate-hostPath"
    match: 
      resources: 
        kinds: 
        - "Pod"
    validate: 
      message: "Host path volumes are not allowed"
      pattern: 
        spec: 
          volumes: 
          - X(hostPath): null