kyverno/samples/more/policy_validate_sysctl_configs.yaml

apiVersion: kyverno.io/v1alpha1
kind: ClusterPolicy
metadata:
  name: validate-allow-portrange-with-sysctl
  annotations:
    policies.kyverno.io/category: Security Context
    policies.kyverno.io/description: The Sysctl interface allows to modify kernel parameters at 
      runtime and in the pod can be specified under 'securityContext.sysctls'. If kernel parameters  
      in the pod are to be modified, should be handled cautiously, and policy with rules restricting 
      these options will be helpful. We can control minimum and maximum port that a network connection 
      can use as its source(local) port by checking 'net.ipv4.ip_local_port_range'.
spec:
  rules:
  - name: allow-portrange-with-sysctl
    match:
      resources:
        kinds:
        - Pod
    validate:
      message: "Allowed port range is from 1024 to 65535"
      pattern:
        spec:
          securityContext:
            sysctls: 
            - name: net.ipv4.ip_local_port_range
              value: "1024 65535"