documentation_complete: true


title: 'Configure the kubelet Certificate Authority for the API Server'

{{% set default_jqfilter = '[.data."config.yaml" | fromjson | select(.apiServerArguments["kubelet-certificate-authority"]) | .apiServerArguments["kubelet-certificate-authority"][] | select(test("{{.var_apiserver_kubelet_certificate_authority}}"))]' %}}
{{% set default_api_path = '/api/v1/namespaces/openshift-kube-apiserver/configmaps/config' %}}
{{% set hypershift_path = '/api/v1/namespaces/{{.hypershift_namespace_prefix}}-{{.hypershift_cluster}}/configmaps/kas-config' %}}
{{% set hypershift_jqfilter = '[.data."config.json" | fromjson | select(.apiServerArguments["kubelet-certificate-authority"]) | .apiServerArguments["kubelet-certificate-authority"][] | select(test("/etc/kubernetes/certs/kubelet-ca/ca.crt"))]' %}}
{{% set custom_api_path = '{{if ne .hypershift_cluster "None"}}' ~ hypershift_path ~ '{{else}}' ~  default_api_path ~ '{{end}}' %}}
{{% set custom_jqfilter = '{{if ne .hypershift_cluster "None"}}' ~ hypershift_jqfilter ~ '{{else}}' ~  default_jqfilter ~ '{{end}}' %}}
{{% set dump_path = default_api_path ~ ',' ~ default_jqfilter ~ ',' ~ custom_jqfilter %}}

description: |-
    To ensure OpenShift verifies kubelet certificates before establishing
    connections, follow the OpenShift documentation and setup the TLS connection
    between the API Server and kubelets.

    Edit the <tt>openshift-kube-apiserver</tt> configmap
    and set the below parameter if it is not already configured:
    <pre>
    "apiServerArguments":{
      ...
      "kubelet-certificate-authority":"/etc/kubernetes/static-pod-resources/configmaps/kubelet-serving-ca/ca-bundle.crt",
      ...
    </pre>

rationale: |-
    Connections from the API Server to the kubelet are used for fetching logs
    for pods, attaching (through kubectl) to running pods, and using the kubelet
    port-forwarding functionality. These connections terminate at the kubelet
    HTTPS endpoint. By default, the API Server does not verify the kubelet serving
    certificate, which makes the connection subject to man-in-the-middle attacks,
    and unsafe to run over untrusted and/or public networks.

identifiers:
  cce@ocp4: CCE-84196-5


severity: high

references:
    cis@ocp4: 1.2.6
    nerc-cip: CIP-003-8 R4.2,CIP-003-8 R6,CIP-004-6 R3,CIP-007-3 R5.1,CIP-007-3 R6.1
    nist: CM-6,CM-6(1),SC-8,SC-8(1)
    pcidss: Req-2.2,Req-2.2.3,Req-2.3
    srg: SRG-APP-000516-CTR-001325

platform: not ocp4-on-hypershift-hosted

ocil_clause: '<tt>kubelet-certificate-authority</tt> is not set as appropriate for <tt>apiServerArguments</tt>'

ocil: |-
    Run the following command:
    <pre>$ oc get configmap config -n openshift-kube-apiserver -ojson | jq -r '.data["config.yaml"]' | jq -r '.apiServerArguments."kubelet-certificate-authority"'</pre>
    The output should return a configured certificate.

warnings:
    - general: |-
        {{{ openshift_filtered_cluster_setting({custom_api_path: dump_path}) | indent(8) }}}

template:
  name: yamlfile_value
  vars:
    ocp_data: "true"
    filepath: {{{ openshift_filtered_path(default_api_path, default_jqfilter) }}}
    yamlpath: "[:]"
    check_existence: "at_least_one_exists"
    entity_check: "all"
    values:
      - value: "(.*?)"
        operation: "pattern match"
