← Policy catalog
</> ValidatingAdmissionPolicy · Apache-2.0

Uses an Unmasked /proc Mount

initcontainer-procmount

severityHigh resourceInitContainers productKubernetes bundles2

An unmasked /proc strips the default masks and read-only paths the runtime applies, exposing kernel memory and tunables such as /proc/kcore and /proc/sys to the init container and easing container escape.

Rejects unless

!has(object.spec.initContainers) || object.spec.initContainers.all(ic,
  !has(ic.securityContext) ||
  !has(ic.securityContext.procMount) ||
  ic.securityContext.procMount == "Default"
)

spec.initContainers[*].securityContext.procMount must be undefined or "Default".

Remediation

Remove securityContext.procMount from every init container or set it back to Default instead of Unmasked. Field: spec.initContainers[*].securityContext.procMount.

Applies to

  • pods · v1 · CREATE, UPDATE

Manifest

apiVersion: admissionregistration.k8s.io/v1
kind: ValidatingAdmissionPolicy
metadata:
  name: initcontainer-procmount
  annotations:
    kubeapt.io/uuid: "5de6bf0d-2a03-45c3-91ce-197bced1ee21"
    security.kubeapt.io/displayName: "Uses an Unmasked /proc Mount"
    security.kubeapt.io/description: "An unmasked /proc strips the default masks and read-only paths the runtime applies, exposing kernel memory and tunables such as /proc/kcore and /proc/sys to the init container and easing container escape."
    security.kubeapt.io/resource: "InitContainers"
    security.kubeapt.io/severity: "High"
    security.kubeapt.io/remediation: "Remove securityContext.procMount from every init container or set it back to Default instead of Unmasked. Field: spec.initContainers[*].securityContext.procMount."
    security.kubeapt.io/product: "Kubernetes"
spec:
  failurePolicy: Fail
  matchConstraints:
    resourceRules:
    - apiGroups:
      - ''
      apiVersions:
      - v1
      operations:
      - CREATE
      - UPDATE
      resources:
      - pods
  validations:
  - expression: |
      !has(object.spec.initContainers) || object.spec.initContainers.all(ic,
        !has(ic.securityContext) ||
        !has(ic.securityContext.procMount) ||
        ic.securityContext.procMount == "Default"
      )
    message: |
      spec.initContainers[*].securityContext.procMount must be undefined or "Default".

Save it as initcontainer-procmount.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 ./initcontainer-procmount.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 initcontainer-procmount -r ./manifests

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

$ kubeapt validate --policy-name initcontainer-procmount -A

Bundles

Source

View policy.yaml on GitHub →