nixos/security/misc: factor out protectKernelImage

Introduces the option security.protectKernelImage that is intended to control
various mitigations to protect the integrity of the running kernel
image (i.e., prevent replacing it without rebooting).

This makes sense as a dedicated module as it is otherwise somewhat difficult
to override for hardened profile users who want e.g., hibernation to work.

1 files changed, 6 insertions, 0 deletions

diff --git a/nixos/tests/hardened.nix b/nixos/tests/hardened.nix
index e10a6363164ac..683f56c45af4a 100644
--- a/nixos/tests/hardened.nix
+++ b/nixos/tests/hardened.nix
@@ -70,5 +70,11 @@ import ./make-test.nix ({ pkgs, ...} : {
         $machine->fail("su -l nobody -s /bin/sh -c 'nix ping-store'");
         $machine->succeed("su -l alice -c 'nix ping-store'") =~ "OK";
       };
+
+      # Test kernel image protection
+      subtest "kernelimage", sub {
+        $machine->fail("systemctl hibernate");
+        $machine->fail("systemctl kexec");
+      };
     '';
 })