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Chapter 24. Configuring SELinux by using the RHEL system role

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You can configure and manage SELinux permissions on other systems by using the selinux RHEL system role.

24.1. Introduction to the selinux RHEL 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 RHEL 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 /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.

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.selinux/README.md file
  • /usr/share/doc/rhel-system-roles/selinux/ directory

24.2. Using the selinux RHEL system role to apply SELinux settings on multiple systems

With the selinux RHEL system role, you can prepare and apply an Ansible playbook with your verified SELinux settings.

Prerequisites

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

  • /usr/share/ansible/roles/rhel-system-roles.selinux/README.md file
  • /usr/share/doc/rhel-system-roles/selinux/ directory
  • SELinux hardening with Ansible Knowledgebase article

24.3. 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 RHEL system 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 RHEL system role, which is more useful when you also make other changes in SELinux configuration. The methods are equivalent, in fact the selinux RHEL system 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.
  • 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 RHEL system role. Create a playbook file, for example, ~/playbook.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
          ansible.builtin.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

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.selinux/README.md file
  • /usr/share/doc/rhel-system-roles/selinux/ directory
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