kyverno/samples/best_practices/disallow_sysctls.yaml

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: disallow-sysctls
  annotations:
    policies.kyverno.io/category: Security
    policies.kyverno.io/description: The Sysctl interface allows modifications to kernel parameters 
      at runtime. In a Kubernetes pod these parameters can be specified under `securityContext.sysctls`. 
      Kernel parameter modifications can be used for exploits and should be restricted.
spec:
  rules:
  - name: validate-sysctls
    match:
      resources:
        kinds:
        - Pod
    validate:
      message: "Changes to kernel paramaters are not allowed"
      pattern:
        spec:
          =(securityContext):
            X(sysctls): null