Linux Security Modules: AppArmor vs SELinux

When it comes to securing computer systems, there are many tools available to administrators. Two of the most popular are AppArmor and SELinux. Both tools are designed to provide an extra layer of security to the system by enforcing Mandatory Access Control (MAC) policies. However, there are some differences between these two tools that are important to understand. In this post, we’ll explore the differences between AppArmor and SELinux.  

What is AppArmor?

AppArmor is a Linux security module that provides mandatory access control for processes. It works by creating a profile for each process on the system. This profile specifies the system resources that the process is allowed to access, such as files, network ports, and system calls. The profile also specifies the actions that the process is allowed to perform on these resources. AppArmor profiles are stored in the file system, typically in the /etc/apparmor.d directory. Each profile is defined in a separate file that contains the rules for that profile. The AppArmor kernel module reads these files at boot time and enforces the access control policies specified in the profiles. For example, a profile might allow a web server process to read files in the /var/www directory, but not write to them.  

What is SELinux?

SELinux is also a Linux security module that provides mandatory access control for processes. Like AppArmor, SELinux works by creating a policy for each process on the system. But SELinux policies are more complex than AppArmor profiles. SELinux policies are based on a set of security contexts that are assigned to system resources, such as files, network ports, and processes. The security contexts in are used to define the relationships between different system resources. For example, a file might have a security context that specifies that it can only be accessed by processes with a specific security context. Processes are also assigned security contexts, which determine the actions that they can perform on system resources.  

AppArmor vs SELinux

While AppArmor and SELinux are both designed to provide mandatory access control for processes, there are some differences between the two tools.

  • Policy Complexity: SELinux policies are generally more complex than AppArmor profiles. This is because SELinux policies use security contexts to define relationships between different system resources. This complexity can make it more difficult to create and maintain SELinux policies.
  • Policy Flexibility: AppArmor profiles are generally more flexible than SELinux policies. This is because AppArmor profiles are created using simple text files, which are easier to read and understand. This simplicity makes it easier to create and maintain AppArmor profiles.
  • Community Support: SELinux is supported by a larger community than AppArmor. This means that there are more resources available for SELinux, such as documentation, tutorials, and forums. However, both tools have active communities and are well-supported.
  • Integration with Distributions: Some Linux distributions, such as Ubuntu, include AppArmor by default. Other distributions, such as Red Hat Enterprise Linux, include SELinux by default. This means that the choice between AppArmor and SELinux may be influenced by the Linux distribution being used.

When to Use AppArmor

AppArmor is a good choice for organizations that need a simple and flexible tool to deploy mandatory access control quickly. It is particularly well-suited for web servers, where it can be used to restrict access to sensitive files and directories. AppArmor profiles can be created and deployed quickly, without requiring extensive testing or customization.  

When to Use SELinux

SELinux is also a good choice for organizations with more complex IT infrastructures, such as large data centers or cloud environments. The complexity of SELinux policies allows for finer-grained control over system resources, which can be useful in these environments.  

Conclusion

Which is better for Linux security: AppArmor or SELinux? It’s a never-ending debate, with both sides having strong arguments. Ultimately, the choice between the two depends on your security needs and preferences.

Abdullah As-Sadeed

Abdullah As-Sadeed