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Disable Mounting of squashfs

An XCCDF Rule

Description

To configure the system to prevent the squashfs kernel module from being loaded, add the following line to the file /etc/modprobe.d/squashfs.conf: 

install squashfs /bin/true
To configure the system to prevent the squashfs from being used, add the following line to file /etc/modprobe.d/squashfs.conf: 
blacklist squashfs
This effectively prevents usage of this uncommon filesystem. The squashfs filesystem type is a compressed read-only Linux filesystem embedded in small footprint systems (similar to cramfs). A squashfs image can be used without having to first decompress the image.

Rationale

Removing support for unneeded filesystem types reduces the local attack surface of the system.

ID
xccdf_org.ssgproject.content_rule_kernel_module_squashfs_disabled
Severity
Low
References
Updated



Remediation - Kubernetes Patch

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

Remediation - Ansible

- name: Ensure kernel module 'squashfs' is disabled
  lineinfile:
    create: true
    dest: /etc/modprobe.d/squashfs.conf
    regexp: install\s+squashfs
    line: install squashfs /bin/false

Remediation - Shell Script

# Remediation is applicable only in certain platforms
if [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; then

if LC_ALL=C grep -q -m 1 "^install squashfs" /etc/modprobe.d/squashfs.conf ; then
	
	sed -i 's#^install squashfs.*#install squashfs /bin/true#g' /etc/modprobe.d/squashfs.conf