Each ComplianceCheckResult represents a result of one compliance rule check. If the rule can be remediated automatically, a ComplianceRemediation object with the same name, owned by the ComplianceCheckResult is created. Unless requested, the remediations are not applied automatically, which gives an OpenShift Container Platform administrator the opportunity to review what the remediation does and only apply a remediation once it has been verified.

Reviewing a remediation

Review both the ComplianceRemediation object and the ComplianceCheckResult object that owns the remediation. The ComplianceCheckResult object contains human-readable descriptions of what the check does and the hardening trying to prevent, as well as other metadata like the severity and the associated security controls. The ComplianceRemediation object represents a way to fix the problem described in the ComplianceCheckResult.

Below is an example of a check and a remediation called sysctl-net-ipv4-conf-all-accept-redirects. This example is redacted to only show spec and status and omits metadata:

spec:
  apply: false
  current:
  object:
    apiVersion: machineconfiguration.openshift.io/v1
    kind: MachineConfig
    spec:
      config:
        ignition:
          version: 2.2.0
        storage:
          files:
            - contents:
              source: data:,net.ipv4.conf.all.accept_redirects%3D0
              filesystem: root
              mode: 420
              path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_all_accept_redirects.conf
  outdated: {}
status:
  applicationState: NotApplied

The remediation payload is stored in the spec.current attribute. The payload can be any Kubernetes object, but because this remediation was produced by a node scan, the remediation payload in the above example is a MachineConfig object. For Platform scans, the remediation payload is often a different kind of an object (for example, a ConfigMap or Secret object), but typically applying that remediation is up to the administrator, because otherwise the Compliance Operator would have required a very broad set of permissions in order to manipulate any generic Kubernetes object. An example of remediating a Platform check is provided later in the text.

To see exactly what the remediation does when applied, the MachineConfig object contents use the Ignition objects for the configuration. Refer to the Ignition specification for further information about the format. In our example, the spec.config.storage.files[0].path attribute specifies the file that is being create by this remediation (/etc/sysctl.d/75-sysctl_net_ipv4_conf_all_accept_redirects.conf) and the spec.config.storage.files[0].contents.source attribute specifies the contents of that file.

The contents of the files are URL-encoded.

Use the following Python script to view the contents:

$ echo "net.ipv4.conf.all.accept_redirects" | python3 -c "import sys, urllib.parse; print(urllib.parse.unquote(''.join(sys.stdin.readlines())))"
Example output
net.ipv4.conf.all.accept_redirects=0

Applying a remediation

The boolean attribute spec.apply controls whether the remediation should be applied by the Compliance Operator. You can apply the remediation by setting the attribute to true:

$ oc patch complianceremediations/<scan_name>-sysctl-net-ipv4-conf-all-accept-redirects --patch '{"spec":{"apply":true}}' --type=merge

After the Compliance Operator processes the applied remediation, the status.ApplicationState attribute would change to Applied or to Error if incorrect. When a machine config remediation is applied, that remediation along with all other applied remediations are rendered into a MachineConfig object named 75-$scan-name-$suite-name. That MachineConfig object is subsequently rendered by the Machine Config Operator and finally applied to all the nodes in a machine config pool by an instance of the machine control daemon running on each node.

Note that when the Machine Config Operator applies a new MachineConfig object to nodes in a pool, all the nodes belonging to the pool are rebooted. This might be inconvenient when applying multiple remediations, each of which re-renders the composite 75-$scan-name-$suite-name MachineConfig object. To prevent applying the remediation immediately, you can pause the machine config pool by setting the .spec.paused attribute of a MachineConfigPool object to true.

The Compliance Operator can apply remediations automatically. Set autoApplyRemediations: true in the ScanSetting top-level object.

Applying remediations automatically should only be done with careful consideration.

Remediating a platform check manually

Checks for Platform scans typically have to be remediated manually by the administrator for two reasons:

  • It is not always possible to automatically determine the value that must be set. One of the checks requires that a list of allowed registries is provided, but the scanner has no way of knowing which registries the organization wants to allow.

  • Different checks modify different API objects, requiring automated remediation to possess root or superuser access to modify objects in the cluster, which is not advised.

Procedure
  1. The example below uses the ocp4-ocp-allowed-registries-for-import rule, which would fail on a default OpenShift Container Platform installation. Inspect the rule oc get rule.compliance/ocp4-ocp-allowed-registries-for-import -oyaml, the rule is to limit the registries the users are allowed to import images from by setting the allowedRegistriesForImport attribute, The warning attribute of the rule also shows the API object checked, so it can be modified and remediate the issue:

    $ oc edit image.config.openshift.io/cluster
    Example output
    apiVersion: config.openshift.io/v1
    kind: Image
    metadata:
      annotations:
        release.openshift.io/create-only: "true"
      creationTimestamp: "2020-09-10T10:12:54Z"
      generation: 2
      name: cluster
      resourceVersion: "363096"
      selfLink: /apis/config.openshift.io/v1/images/cluster
      uid: 2dcb614e-2f8a-4a23-ba9a-8e33cd0ff77e
    spec:
      allowedRegistriesForImport:
      - domainName: registry.redhat.io
    status:
      externalRegistryHostnames:
      - default-route-openshift-image-registry.apps.user-cluster-09-10-12-07.devcluster.openshift.com
      internalRegistryHostname: image-registry.openshift-image-registry.svc:5000
  2. Re-run the scan:

    $ oc annotate compliancescans/<scan_name> compliance.openshift.io/rescan=

Updating remediations

When a new version of compliance content is used, it might deliver a new and different version of a remediation than the previous version. The Compliance Operator will keep the old version of the remediation applied. The OpenShift Container Platform administrator is also notified of the new version to review and apply. A ComplianceRemediation object that had been applied earlier, but was updated changes its status to Outdated. The outdated objects are labeled so that they can be searched for easily.

The previously applied remediation contents would then be stored in the spec.outdated attribute of a ComplianceRemediation object and the new updated contents would be stored in the spec.current attribute. After updating the content to a newer version, the administrator then needs to review the remediation. As long as the spec.outdated attribute exists, it would be used to render the resulting MachineConfig object. After the spec.outdated attribute is removed, the Compliance Operator re-renders the resulting MachineConfig object, which causes the Operator to push the configuration to the nodes.

Procedure
  1. Search for any outdated remediations:

    $ oc get complianceremediations -lcomplianceoperator.openshift.io/outdated-remediation=
    Example output
    NAME                              STATE
    workers-scan-no-empty-passwords   Outdated

    The currently applied remediation is stored in the Outdated attribute and the new, unapplied remediation is stored in the Current attribute. If you are satisfied with the new version, remove the Outdated field. If you want to keep the updated content, remove the Current and Outdated attributes.

  2. Apply the newer version of the remediation:

    $ oc patch complianceremediations workers-scan-no-empty-passwords --type json -p '[{"op":"remove", "path":/spec/outdated}]'
  3. The remediation state will switch from Outdated to Applied:

    $ oc get complianceremediations workers-scan-no-empty-passwords
    Example output
    NAME                              STATE
    workers-scan-no-empty-passwords   Applied
  4. The nodes will apply the newer remediation version and reboot.

Unapplying a remediation

It might be required to unapply a remediation that was previously applied.

Procedure
  1. Toggle the flag to false:

    $ oc patch complianceremediations/<scan_name>-sysctl-net-ipv4-conf-all-accept-redirects
  2. The remediation status will change to NotApplied and the composite MachineConfig object would be re-rendered to not include the remediation.

    All affected nodes with the remediation will be rebooted.

Inconsistent remediations

The ScanSetting lists the node roles that the compliance scans generated from the ScanSetting or ScanSettingBinding would scan. Each node role usually maps to a machine config pool.

It is expected that all machines in a machine config pool are identical and all scan results from the nodes in a Pool should be identical.

If some of the results are different from others, the Compliance Operator flags a ComplianceCheckResult object where some of the nodes will report as INCONSISTENT. All ComplianceCheckResult objects are also labeled with compliance.openshift.io/inconsistent-check.

Because the number of machines in a pool might be quite large, the Compliance Operator attempts to find the most common state and list the nodes that differ from the common state. The most common state is stored in the compliance.openshift.io/most-common-status annotation and the annotation compliance.openshift.io/inconsistent-source contains pairs of hostname:status of check statuses that differ from the most common status. If no common state can be found, all the hostname:status pairs are listed in the compliance.openshift.io/inconsistent-source annotation.

If possible, a remediation is still created so that the cluster can converge to a compliant status. However, this might not always be possible and correcting the difference between nodes must be done manually. The ComplianceScan must be re-run to get a consistent result by annotating the scan with the compliance.openshift.io/rescan= option:

$ oc annotate compliancescans/<scan_name> compliance.openshift.io/rescan=