Nov 29, 2025
Landlock: What Is It?
Landlock is a Linux API that lets applications explicitly declare which resources they are allowed to access. Its philosophy is similar to OpenBSD’s unveil() and (less so) pledge() : programs can make a contract with the kernel stating, “I only need these files or resources — deny me everything else if I’m compromised.”
It provides a simple, developer-friendly way to add defense-in-depth to applications. Compared to traditional Linux security mechanisms, Landlock is vastly easier to understand and integrate.
This post is meant to be an accessible introduction, and hopefully persuade you to give Landlock a try.
How Does It Work?
Landlock is a Linux Security Module (LSM) available since Linux 5.13. Unlike MAC frameworks such as SELinux or AppArmor, Landlock applies transient restrictions: policies are created at runtime, enforced on the current thread and its future descendants, and disappear when the process exits.
You don’t tag files with labels or extended attributes. Instead, applications create policies dynamically.
A Landlock policy consists of two pieces:
Handled accesses — the categories of operations you want to restrict (e.g., filesystem read/write). Access grants — an explicit allowlist of which objects are permitted for those operations.
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