AppArmor vs. SELinux Comprehensive Comparison

In world of cybersecurity, there are two commonly used tools for enforcing mandatory access control (MAC) policies on Linux systems: AppArmor and SELinux. Both of these tools provide a layer of security by limiting actions that a particular process or application can take on a system. In this article, we will be taking a comprehensive look at both AppArmor and SELinux and compare their features and capabilities.

Overview of AppArmor and SELinux

AppArmor and SELinux are both Linux security modules (LSMs) that can be used to protect a system from various security threats. They are designed to restrict actions of applications, processes, and users on a system. Both tools use MAC policies to determine what actions are allowed and what actions are not.

AppArmor was developed by Novell, and it was initially released in 2005. It is an LSM that is designed to be easy to use and deploy. AppArmor uses a profile-based approach to security, where each application has its own security profile. These profiles specify what actions an application can take, such as accessing certain files or network ports.

On other hand, SELinux was developed by US National Security Agency (NSA) and was first released in 2000. SELinux is a more complex LSM that uses a mandatory access control (MAC) policy. This policy specifies what actions are allowed on a system and what actions are not. Unlike AppArmor, SELinux is not profile-based, and it requires a lot of configuration to set up.

Ease of Use

One of major differences between AppArmor and SELinux is ease of use. AppArmor is designed to be easy to use and deploy, while SELinux is more complex and requires a lot of configuration.

AppArmor uses a profile-based approach to security, where each application has its own security profile. These profiles are easy to create and modify, making it simple to apply security policies to new applications. Additionally, AppArmor is easy to use because it is integrated with many Linux distributions, including Ubuntu, Debian, and OpenSUSE. This integration makes it simple to deploy AppArmor and start using it right away.

In contrast, SELinux is more complex and difficult to use. It requires a lot of configuration to set up, and it does not use a profile-based approach to security. Instead, SELinux uses a mandatory access control (MAC) policy, which specifies what actions are allowed on a system and what actions are not. This policy can be difficult to understand and configure, making SELinux a more challenging LSM to use.

Performance

Another important factor to consider when comparing AppArmor and SELinux is their performance. Both tools have an impact on system performance, but extent of that impact varies.

AppArmor is known for having a lower impact on system performance compared to SELinux. This is because AppArmor uses a profile-based approach to security, which is less complex than mandatory access control (MAC) policy used by SELinux. Additionally, AppArmor profiles can be compiled into kernel, which can reduce overhead of enforcing security policies.

On other hand, SELinux is known for having a higher impact on system performance compared to AppArmor. This is because SELinux uses a mandatory access control (MAC) policy, which is more complex than profile-based approach used by AppArmor. Additionally, SELinux policies cannot be compiled into kernel, which can result in higher overhead when enforcing security policies.

Flexibility

Flexibility is another factor to consider when comparing AppArmor and SELinux. Both tools have different levels of flexibility in terms of what actions they can restrict and how those restrictions are applied.

AppArmor is more flexible in terms of what actions it can restrict. This is because AppArmor uses a profile-based approach to security, which allows for granular control over what actions an application can take. This means that it is easy to restrict specific actions, such as accessing a particular file or network port, without affecting other actions that are allowed.

On other hand, SELinux is less flexible in terms of what actions it can restrict. This is because SELinux uses a mandatory access control (MAC) policy, which restricts all actions that are not explicitly allowed. This means that it can be difficult to restrict specific actions without also restricting other actions that are allowed.

However, SELinux is more flexible in terms of how restrictions are applied. SELinux policies can be customized to apply different levels of security based on context in which an application is running. This means that SELinux can provide stronger security in situations where it is needed, such as in a high-security environment.

Community Support

Community support is an important factor to consider when choosing a security tool. Both AppArmor and SELinux have active communities of users and developers, but there are differences in level of support available.

AppArmor has a large and active community of users and developers. It is integrated with many Linux distributions, including Ubuntu, Debian, and OpenSUSE. This means that there are many resources available for learning about AppArmor and getting help with any issues that may arise.

SELinux also has a large and active community of users and developers, but it is less integrated with Linux distributions. This means that it can be more difficult to get started with SELinux and find resources for learning about it.

AppArmor vs. SELinux in Table Format

Feature	SELinux	AppArmor
Automated	No - audit2allow and system-config-selinux	Yes - Yast wizard
Powerful Policy Setup	Yes - Very complex	Yes
Default and Recommended integration	CetOS/RedHat/Debian	SUSE/OpenSUSE
Training and Vendor Support	Yes - Redhat	Yes - Novell
Recommended for	Advanced Users	New/Advanced Users
Feature	Pathname based system does not require labelling or relabelling filesystem	Attaches labels to all files, processes and objects

Examples of AppArmor and SELinux in Action

To better understand how AppArmor and SELinux work in practice, here are some examples of how they can be used to enforce security policies on a Linux system.

Example 1: Restricting Access to Files

Suppose you have an application that needs to access a specific file on your Linux system. You want to restrict access to this file so that only application can access it.

With AppArmor, you can create a profile for application that specifies which files it is allowed to access. This profile can be easily modified to restrict access to specific file in question.

With SELinux, you can create a policy that allows application to access specific file in question, while restricting access to other files.

Example 2: Restricting Access to Network Ports

Suppose you have a server running on your Linux system that listens on a specific network port. You want to restrict access to this port so that only certain applications can connect to it.

With AppArmor, you can create a profile for server that specifies which network ports it is allowed to listen on. This profile can be easily modified to restrict access to specific port in question.

With SELinux, you can create a policy that allows server to listen on specific port in question, while restricting access to other ports.

Conclusion

In conclusion, both AppArmor and SELinux are powerful tools for enforcing mandatory access control (MAC) policies on Linux systems. AppArmor is designed to be easy to use and deploy, while SELinux is more complex and requires a lot of configuration to set up. AppArmor has a lower impact on system performance compared to SELinux, but SELinux is more flexible in terms of how restrictions are applied. Both tools have active communities of users and developers, but AppArmor is more integrated with Linux distributions. Ultimately, choice between AppArmor and SELinux depends on specific security requirements and constraints of your system.