some security updates

hosts/thinkpad/kernel.nix

@@ -0,0 +1,24 @@
+{ config, pkgs, stdenv, ... }:
+
+{
+  boot.kernelPackages = pkgs.linuxPackages_hardened;
+  boot.kernelParams = [
+    # Disable slab merging to prevent heap exploitation
+    "slab_nomerge"
+    # Enable zeroing memory during allocation and free time
+    "init_on_alloc=1"
+    "init_on_free=1"
+    # Randomize page allocator freelists
+    "page_alloc.shuffle=1"
+    # Mitigations
+    "pti=on"
+
+    "vsyscall=none"
+    "debugfs=off"
+    "oops=panic"
+
+    # Enable lockdown LSM
+    "lockdown=confidentiality"
+  ];
+
+}