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Chapter 10. Deploying the same SELinux configuration on multiple systems

You can deploy your verified SELinux configuration on multiple systems by using one of the following methods:

  • Using RHEL System Roles and Ansible
  • Using semanage export and import commands in your scripts

10.1. Introduction to the selinux System Role

RHEL System Roles is a collection of Ansible roles and modules that provide a consistent configuration interface to remotely manage multiple RHEL systems. You can perform the following actions by using the selinux System Role:

  • Cleaning local policy modifications related to SELinux booleans, file contexts, ports, and logins.
  • Setting SELinux policy booleans, file contexts, ports, and logins.
  • Restoring file contexts on specified files or directories.
  • Managing SELinux modules.

The following table provides an overview of input variables available in the selinux System Role.

Table 10.1. selinux System Role variables

Role variableDescriptionCLI alternative

selinux_policy

Chooses a policy protecting targeted processes or Multi Level Security protection.

SELINUXTYPE in /etc/selinux/config

selinux_state

Switches SELinux modes.

setenforce and SELINUX in /etc/selinux/config.

selinux_booleans

Enables and disables SELinux booleans.

setsebool

selinux_fcontexts

Adds or removes a SELinux file context mapping.

semanage fcontext

selinux_restore_dirs

Restores SELinux labels in the file-system tree.

restorecon -R

selinux_ports

Sets SELinux labels on ports.

semanage port

selinux_logins

Sets users to SELinux user mapping.

semanage login

selinux_modules

Installs, enables, disables, or removes SELinux modules.

semodule

The /usr/share/doc/rhel-system-roles/selinux/example-selinux-playbook.yml example playbook installed by the rhel-system-roles package demonstrates how to set the targeted policy in enforcing mode. The playbook also applies several local policy modifications and restores file contexts in the /tmp/test_dir/ directory.

For a detailed reference on selinux role variables, install the rhel-system-roles package, and see the README.md or README.html files in the /usr/share/doc/rhel-system-roles/selinux/ directory.

Additional resources

10.2. Using the selinux System Role to apply SELinux settings on multiple systems

With the selinux System Role, you can prepare and apply an Ansible playbook with your verified SELinux settings.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.

Procedure

  1. Prepare your playbook. You can either start from scratch or modify the example playbook installed as a part of the rhel-system-roles package: 

    # cp /usr/share/doc/rhel-system-roles/selinux/example-selinux-playbook.yml <my-selinux-playbook.yml>
# vi <my-selinux-playbook.yml>

  2. Change the content of the playbook to fit your scenario. For example, the following part ensures that the system installs and enables the selinux-local-1.pp SELinux module: 

    selinux_modules:
- { path: "selinux-local-1.pp", priority: "400" }
  3. Save the changes, and exit the text editor.

  4. Validate the playbook syntax: 

    # ansible-playbook <my-selinux-playbook.yml> --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  5. Run your playbook: 

    # ansible-playbook <my-selinux-playbook.yml>

Additional resources

  • For more information, install the rhel-system-roles package, and see the /usr/share/doc/rhel-system-roles/selinux/ and /usr/share/ansible/roles/rhel-system-roles.selinux/ directories.
  • SELinux hardening with Ansible Knowledgebase article

10.3. Managing ports by using the selinux RHEL System Role

You can automate managing port access in SELinux consistently across multiple systems by using the selinux RHEL System Role. This might be useful, for example, when configuring an Apache HTTP server to listen on a different port. You can do this by creating a playbook with the selinux role that assigns the http_port_t SELinux type to a specific port number. After you run the playbook on the managed nodes, specific services defined in the SELinux policy can access this port.

You can automate managing port access in SELinux either by using the seport module, which is quicker than using the entire role, or by using the selinux role, which is more useful when you also make other changes in SELinux configuration. The methods are equivalent, in fact the selinux role uses the seport module when configuring ports. Each of the methods has the same effect as entering the command semanage port -a -t http_port_t -p tcp <port_number> on the managed node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.
  • Optional: To verify port status by using the semanage command, the policycoreutils-python-utils package must be installed.

Procedure

  • To configure just the port number without making other changes, use the seport module: 

    - name: Allow Apache to listen on tcp port <port_number>
  community.general.seport:
    ports: <port_number>
    proto: tcp
    setype: http_port_t
    state: present

    Replace <port_number> with the port number to which you want to assign the http_port_t type.

  • For more complex configuration of the managed nodes that involves other customizations of SELinux, use the selinux role. Create a playbook file, for example, ~/selinux-custom-ports.yml, and add the following content: 

    ---
- name: Modify SELinux port mapping example
  hosts: all
  vars:
    # Map tcp port <port_number> to the 'http_port_t' SELinux port type
    selinux_ports:
      - ports: <port_number>
        proto: tcp
        setype: http_port_t
        state: present

  tasks:
  - name: Include selinux role
    include_role:
      name: rhel-system-roles.selinux

    Replace <port_number> with the port number to which you want to assign the http_port_t type.

Verification

  • Verify that the port is assigned to the http_port_t type: 

    # semanage port --list | grep http_port_t
http_port_t                	tcp  	<port_number>, 80, 81, 443, 488, 8008, 8009, 8443, 9000

10.4. Transferring SELinux settings to another system with semanage

Use the following steps for transferring your custom and verified SELinux settings between RHEL 8-based systems.

Prerequisites

  • The policycoreutils-python-utils package is installed on your system.

Procedure

  1. Export your verified SELinux settings: 

    # semanage export -f ./my-selinux-settings.mod

  2. Copy the file with the settings to the new system: 

    # scp ./my-selinux-settings.mod new-system-hostname:

  3. Log in on the new system: 

    $ ssh root@new-system-hostname

  4. Import the settings on the new system: 

    new-system-hostname# semanage import -f ./my-selinux-settings.mod

Additional resources

  • semanage-export(8) and semanage-import(8) man pages