NixOS must implement nonexecutable data to protect its memory from unauthorized code execution.

Some adversaries launch attacks with the intent of executing code in nonexecutable regions of memory or in memory locations that are prohibited. Security safeguards employed to protect memory include, for example, data execution prevention and address space layout randomization. Data execution prevention safeguards can either be hardware-enforced or software-enforced with hardware providing the greater strength of mechanism.

Examples of attacks are buffer overflow attacks.

Satisfies: SRG-OS-000433-GPOS-00192, SRG-OS-000132-GPOS-00067

Verify NixOS prevents internal kernel addresses from being leaked with the following command:

$ sudo sysctl kernel.kptr_restrict

kernel.kptr_restrict = 1

If "kernel.kptr_restrict" does not have a value of "1" or is missing, this is a finding.

Configure NixOS to prevent internal kernel addresses from being leaked.

Add the following Nix code to the NixOS Configuration, usually located in /etc/nixos/configuration.nix or /etc/nixos/flake.nix:

boot.kernel.sysctl = { "kernel.kptr_restrict" = 1; };

Rebuild and switch to the new NixOS configuration: $ sudo nixos-rebuild switch