M-110_sysctls.yml

# Copyright 2023 Undistro Authors
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# https://kubernetes.io/docs/concepts/security/pod-security-standards/#baseline
# https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/pod-security-admission/policy/check_sysctls.go
# https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/pod-security-admission/policy/check_sysctls_test.go
id: M-110
slug: sysctls
severity: Medium
message: "Unsafe sysctls"
match:
  resources:
    - group: ""
      version: v1
      resource: pods
    - group: apps
      version: v1
      resource: deployments
    - group: apps
      version: v1
      resource: daemonsets
    - group: apps
      version: v1
      resource: statefulsets
    - group: apps
      version: v1
      resource: replicasets
    - group: batch
      version: v1
      resource: cronjobs
    - group: batch
      version: v1
      resource: jobs
params:
  allowedSysctls:
    - 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
variables:
  - name: sysctls
    expression: podSpec.?securityContext.?sysctls.orValue([])
validations:
  - expression: >
      variables.sysctls.size() == 0 || variables.sysctls.all(s,
        s.name == null ||
        s.name in params.allowedSysctls
      )
    message: "Pod using unsafe sysctls"