Puppet Class: cis_security_hardening::rules::overlayfs

Defined in:
manifests/rules/overlayfs.pp

Summary

Ensure overlayfs kernel module is not available

Overview

The overlay filesystem combines multiple different directories into a single directory. It is commonly used for containers and package management systems. The overlayfs filesystem type allows one, usually read-write, directory tree to be overlaid onto another, read-only directory tree.

Rationale: Removing support for unneeded filesystem types reduces the local attack surface of the system. If this filesystem type is not needed, disable it.

Examples:

class { 'cis_security_hardening::rules::overlayfs':
    enforce => true,
}

Parameters:

  • enforce (Boolean) (defaults to: false) —

    Enforce the rule



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# File 'manifests/rules/overlayfs.pp', line 21

class cis_security_hardening::rules::overlayfs (
  Boolean $enforce = false,
) {
  if $enforce {
    case $facts['os']['name'].downcase() {
      'rocky', 'almalinux', 'centos': {
        kmod::install { 'overlay':
          command => '/bin/false',
        }
        kmod::blacklist { 'overlay': }
      }
      'redhat': {
        if $facts['os']['release']['major'] > '7' {
          kmod::install { 'overlay':
            command => '/bin/false',
          }
          kmod::blacklist { 'overlay': }
        } else {
          kmod::install { 'overlay':
            command => '/bin/true',
          }
        }
      }
      'debian': {
        if $facts['os']['release']['major'] > '10' {
          kmod::install { 'overlay':
            command => '/bin/false',
          }
          kmod::blacklist { 'overlay': }
        } else {
          kmod::install { 'overlay':
            command => '/bin/true',
          }
        }
      }
      'ubuntu': {
        if $facts['os']['release']['major'] >= '20' {
          kmod::install { 'overlay':
            command => '/bin/false',
          }
          kmod::blacklist { 'overlay': }
        } else {
          kmod::install { 'overlay':
            command => '/bin/true',
          }
        }
      }
      default: {
        kmod::install { 'overlay':
          command => '/bin/true',
        }
      }
    }
  }
}