SELinux Cookbook

The SELinux (Security Enhanced Linux) cookbook provides recipes for manipulating SELinux policy enforcement state.

SELinux can have one of three settings:

Enforcing

• Watches all system access checks, stops all 'Denied access'
• Default mode on RHEL systems

Permissive

• Allows access but reports violations

Disabled

• Disables SELinux from the system but is only read at boot time. If you set this flag, you must reboot.

Disable SELinux only if you plan to not use it. Use Permissive mode if you just need to debug your system.

Requirements

• Chef 13 or higher

Platform:

• RHEL 6/7

Attributes

• node['selinux']['state'] - The SELinux policy enforcement state. The state to set by default, to match the default SELinux state on RHEL. Can be "enforcing", "permissive", "disabled"
• node['selinux']['booleans'] - A hash of SELinux boolean names and the values they should be set to. Values can be off, false, or 0 to disable; or on, true, or 1 to enable.

Resources Overview

selinux_state

The selinux_state resource is used to manage the SELinux state on the system. It does this by using the setenforce command and rendering

the /etc/selinux/config file from a template.

selinux_module

This provider is intended to be part of the SELinux analysis workflow using tools like audit2allow.

Actions

• :create: install the module;
• :remove: remove the module;

Options

• source: SELinux .te file, to be parsed, compiled and deployed as module. If simple basename informed, the provider will first look into files/default/selinux directory;
• base_dir: Base directory to create and manage SELinux files, by default is /etc/selinux/local;
• force: Boolean. Indicates if provider should re-install the same version of SELinux module already installed, in case the source .te file changes;

Attributes

LWRP interface, recipe attributes are not applicable here.

selinux_state

The selinux_state resource is used to manage the SELinux state on the system. It does this by using the setenforce command and rendering the /etc/selinux/config file from a template.

Actions

• :nothing: default action, does nothing
• :enforcing: Sets SELinux to enforcing.
• :disabled: Sets SELinux to disabled.
• :permissive: Sets SELinux to permissive.

Properties

• temporary - true, false, default false. Allows the temporary change between permissive and enabled states which don't require a reboot.
• selinuxtype - targeted, mls, default targeted. Determines the policy that will be configured in the /etc/selinux/config file. The default value is targeted which enables selinux in a mode where only selected processes are protected. mls is multilevel security which enables selinux in a mode where all processes are protected.

Examples

Managing SELinux State (selinux_state)

Simply set SELinux to enforcing or permissive:

selinux_state "SELinux Enforcing" do
  action :enforcing
end

selinux_state "SELinux Permissive" do
  action :permissive
end

The action here is based on the value of the node['selinux']['state'] attribute, which we convert to lower-case and make a symbol to pass to the action.

selinux_state "SELinux #{node['selinux']['state'].capitalize}" do
  action node['selinux']['state'].downcase.to_sym
end

The action here is based on the value of the node['selinux']['status'] attribute, which we convert to lower-case and make a symbol to pass to the action.

selinux_state "SELinux #{node['selinux']['status'].capitalize}" do
  action node['selinux']['status'].downcase.to_sym
end

Managing SELinux Modules (selinux_module)

Consider the following steps to obtain a .te file, the rule description format employed on SELinux

1. Add selinux to your metadata.rb, as for instance: depends 'selinux', '>= 0.10.0';
2. Run your SELinux workflow, and add .te files on your cookbook files, preferably under files/default/selinux directory;
3. Write recipes using selinux_module provider;

SELinux audit2allow Workflow

This provider was written with the intention of matching the workflow of audit2allow (provided by package policycoreutils), which basically will be:

1. Test application and inspect /var/log/audit/audit.log log-file with a command like this basic example: grep AVC /var/log/audit/audit.log |audit2allow -M my_application;
2. Save my_application.te SELinux module source, copy into your cookbook under files/default/selinux/my_application.te;
3. Make use of selinux provider on a recipe, after adding it as a dependency;

For example, add the following on the recipe level:

selinux_module 'MyApplication SELinux Module' do
  source 'my_application.te'
  action :create
end

Module name is defined on my_application.te file contents, please note this input, is used during :remove action. For instance:

selinux_module 'my_application' do
  action :remove
end

selinux_install

The selinux_install resource is used to encapsulate the set of selinux packages to install in order to manage selinux. It also ensures the directory /etc/selinux is created.

Recipes

All recipes will deprecate in the near future as they are just using the selinux_state resource.

default

The default recipe will use the attribute node['selinux']['status'] in the selinux_state resource's action. By default, this will be :enforcing.

enforcing

This recipe will use :enforcing as the selinux_state action.

permissive

This recipe will use :permissive as the selinux_state action.

disabled

This recipe will use :disabled as the selinux_state action.

Usage

By default, this cookbook will have SELinux enforcing by default, as the default recipe uses the node['selinux']['status'] attribute, which is "enforcing." This is in line with the policy of enforcing by default on RHEL family distributions.

You can simply set the attribute in a role applied to the node:

name "base"
description "Base role applied to all nodes."
default_attributes(
  "selinux" => {
    "status" => "permissive"
  }
)

Or, you can apply the recipe to the run list (e.g., in a role):

name "base"
description "Base role applied to all nodes."
run_list(
  "recipe[selinux::permissive]",
)

License & Authors

• Author: Sean OMeara ([email protected])
• Author: Joshua Timberman ([email protected])
• Author: Jennifer Davis ([email protected])

Copyright: 2008-2018, Chef Software, Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.