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Disable the use of user namespaces

An XCCDF Rule

Description

To set the runtime status of the user.max_user_namespaces kernel parameter, run the following command: 

$ sudo sysctl -w user.max_user_namespaces=0
To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: 
user.max_user_namespaces = 0
When containers are deployed on the machine, the value should be set to large non-zero value.

warning alert: Warning

This configuration baseline was created to deploy the base operating system for general purpose workloads. When the operating system is configured for certain purposes, such as to host Linux Containers, it is expected that user.max_user_namespaces will be enabled.

Rationale

It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or system objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. User namespaces are used primarily for Linux containers. The value 0 disallows the use of user namespaces.

ID
xccdf_org.ssgproject.content_rule_sysctl_user_max_user_namespaces
Severity
Medium
References
Updated



Remediation - Kubernetes Patch

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition: