Adds a Capability Outside the Baseline Set

apiVersion: admissionregistration.k8s.io/v1
kind: ValidatingAdmissionPolicy
metadata:
  name: container-capabilities-add
  annotations:
    kubeapt.io/uuid: "57487b22-099b-46ad-b669-844e1e392a65"
    security.kubeapt.io/displayName: "Adds a Capability Outside the Baseline Set"
    security.kubeapt.io/description: "Linux capabilities beyond the baseline set, such as SYS_ADMIN, SYS_MODULE, SYS_PTRACE or NET_RAW, hand a container kernel level privileges it can use to mount filesystems, load modules and break out onto the node."
    security.kubeapt.io/resource: "Containers"
    security.kubeapt.io/severity: "Moderate"
    security.kubeapt.io/remediation: "Drop the non-baseline entries from the added capability list and keep only baseline names such as CHOWN, KILL, SETGID, SETUID and NET_BIND_SERVICE. Field: spec.containers[*].securityContext.capabilities.add."
    security.kubeapt.io/product: "Kubernetes"
spec:
  failurePolicy: Fail
  matchConstraints:
    resourceRules:
    - apiGroups:
      - ''
      apiVersions:
      - v1
      operations:
      - CREATE
      - UPDATE
      resources:
      - pods
  variables:
  - name: allowedCaps
    expression: |
      ["AUDIT_WRITE","CHOWN","DAC_OVERRIDE","FOWNER","FSETID","KILL","MKNOD","NET_BIND_SERVICE","SETFCAP","SETGID","SETPCAP","SETUID","SYS_CHROOT"]
  validations:
  - expression: |
      (has(object.spec.os) &&
       has(object.spec.os.name) &&
       object.spec.os.name.lowerAscii() == "windows") ||
      object.spec.containers.all(c,
        !has(c.securityContext) ||
        !has(c.securityContext.capabilities) ||
        !has(c.securityContext.capabilities.add) ||
        c.securityContext.capabilities.add.all(cap,
          variables.allowedCaps.exists(a, a == cap)
        )
      )
    message: |
      Only the baseline capabilities may be added: AUDIT_WRITE, CHOWN, DAC_OVERRIDE, FOWNER, FSETID, KILL, MKNOD, NET_BIND_SERVICE, SETFCAP, SETGID, SETPCAP, SETUID, SYS_CHROOT.