checkmodule - Linux

Overview

checkmodule is a tool used to analyze Security-Enhanced Linux (SELinux) module source code or binary modules and check for potential security flaws or policy violations. It helps ensure that SELinux policies are secure, consistent, and maintainable.

Syntax

checkmodule [options] [module_file]

Options/Flags

• -m: Specify the module type to validate. Can be either "policy" (default) or "cil".
• -M: Specify the SELinux mode to use for validation. Can be "enforcing" (default), "permissive", or "disabled".
• -o: Specify the output file. By default, results are printed to the standard output.
• -v: Enable verbose output with additional information.
• -h: Display usage information.

Examples

Simple Validation:

checkmodule example_module.te

Validation with Specific SELinux Mode:

checkmodule -M permissive example_module.pp

Output to a File:

checkmodule -o validation_report.txt example_module.cil

Common Issues

• Module Syntax Errors: Make sure the module source code adheres to the SELinux policy language syntax.
• Duplicate or Conflicting Labels: Check for duplicate or overlapping labels that could lead to policy violations.
• Undefined Types or Attributes: Ensure that all types and attributes used in the module are properly defined.
• Insufficient Permissions: Check for missing or incorrect permissions that could allow unauthorized access or operations.

Integration

With semanage:

semanage import -m example_module
checkmodule example_module.cil

With audit2allow:

audit2allow -m example_module
checkmodule example_module.te

Related Commands

• semanage: Manage SELinux policies and configuration.
• audit2allow: Generate SELinux policies based on system audit events.