Restrict sysctls

 1apiVersion: kyverno.io/v1
 2kind: ClusterPolicy
 3metadata:
 4  name: restrict-sysctls
 5  annotations:
 6    policies.kyverno.io/title: Restrict sysctls
 7    policies.kyverno.io/category: Pod Security Standards (Baseline)
 8    policies.kyverno.io/severity: medium
 9    policies.kyverno.io/subject: Pod
10    kyverno.io/kyverno-version: 1.6.0
11    kyverno.io/kubernetes-version: "1.22-1.23"
12    policies.kyverno.io/description: >-
13      Sysctls can disable security mechanisms or affect all containers on a
14      host, and should be disallowed except for an allowed "safe" subset. A
15      sysctl is considered safe if it is namespaced in the container or the
16      Pod, and it is isolated from other Pods or processes on the same Node.
17      This policy ensures that only those "safe" subsets can be specified in
18      a Pod.      
19spec:
20  validationFailureAction: audit
21  background: true
22  rules:
23    - name: check-sysctls
24      match:
25        any:
26        - resources:
27            kinds:
28              - Pod
29      validate:
30        message: >-
31          Setting additional sysctls above the allowed type is disallowed.
32          The field spec.securityContext.sysctls must be unset or not use any other names
33          than kernel.shm_rmid_forced, net.ipv4.ip_local_port_range,
34          net.ipv4.ip_unprivileged_port_start, net.ipv4.tcp_syncookies and
35          net.ipv4.ping_group_range.          
36        pattern:
37          spec:
38            =(securityContext):
39              =(sysctls):
40                - =(name): "kernel.shm_rmid_forced | net.ipv4.ip_local_port_range | net.ipv4.ip_unprivileged_port_start | net.ipv4.tcp_syncookies | net.ipv4.ping_group_range"
41