linux/hardened: move files into directory

2020-05-08 15:49:35 +01:00
parent abe4bef033
commit d6fe0a4e2d
9 changed files with 14 additions and 12 deletions
@@ -0,0 +1,85 @@
+# Based on recommendations from:
+# http://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project#Recommended_settings
+# https://wiki.gentoo.org/wiki/Hardened/Hardened_Kernel_Project
+#
+# Dangerous features that can be permanently (for the boot session) disabled at
+# boot via sysctl or kernel cmdline are left enabled here, for improved
+# flexibility.
+#
+# See also <nixos/modules/profiles/hardened.nix>
+
+{ stdenv, version }:
+
+with stdenv.lib;
+with stdenv.lib.kernel;
+with (stdenv.lib.kernel.whenHelpers version);
+
+assert (versionAtLeast version "4.9");
+
+{
+  # Report BUG() conditions and kill the offending process.
+  BUG = yes;
+
+  # Safer page access permissions (wrt. code injection).  Default on >=4.11.
+  DEBUG_RODATA          = whenOlder "4.11" yes;
+  DEBUG_SET_MODULE_RONX = whenOlder "4.11" yes;
+
+  # Mark LSM hooks read-only after init.  SECURITY_WRITABLE_HOOKS n
+  # conflicts with SECURITY_SELINUX_DISABLE y; disabling the latter
+  # implicitly marks LSM hooks read-only after init.
+  #
+  # SELinux can only be disabled at boot via selinux=0
+  #
+  # We set SECURITY_WRITABLE_HOOKS n primarily for documentation purposes; the
+  # config builder fails to detect that it has indeed been unset.
+  SECURITY_SELINUX_DISABLE = whenAtLeast "4.12" no;
+  SECURITY_WRITABLE_HOOKS  = whenAtLeast "4.12" (option no);
+
+  STRICT_KERNEL_RWX = whenAtLeast "4.11" yes;
+
+  # Perform additional validation of commonly targeted structures.
+  DEBUG_CREDENTIALS     = yes;
+  DEBUG_NOTIFIERS       = yes;
+  DEBUG_PI_LIST         = yes; # doesn't BUG()
+  DEBUG_SG              = yes;
+  SCHED_STACK_END_CHECK = yes;
+
+  REFCOUNT_FULL = whenAtLeast "4.13" yes;
+
+  # Randomize page allocator when page_alloc.shuffle=1
+  SHUFFLE_PAGE_ALLOCATOR = whenAtLeast "5.2" yes;
+
+  # Allow enabling slub/slab free poisoning with slub_debug=P
+  SLUB_DEBUG = yes;
+
+  # Wipe higher-level memory allocations on free() with page_poison=1
+  PAGE_POISONING           = yes;
+  PAGE_POISONING_NO_SANITY = yes;
+  PAGE_POISONING_ZERO      = yes;
+
+  # Enable the SafeSetId LSM
+  SECURITY_SAFESETID = whenAtLeast "5.1" yes;
+
+  # Reboot devices immediately if kernel experiences an Oops.
+  PANIC_TIMEOUT = freeform "-1";
+
+  GCC_PLUGINS = yes; # Enable gcc plugin options
+  # Gather additional entropy at boot time for systems that may = no;ot have appropriate entropy sources.
+  GCC_PLUGIN_LATENT_ENTROPY = yes;
+
+  GCC_PLUGIN_STRUCTLEAK = whenAtLeast "4.11" yes; # A port of the PaX structleak plugin
+  GCC_PLUGIN_STRUCTLEAK_BYREF_ALL = whenAtLeast "4.14" yes; # Also cover structs passed by address
+  GCC_PLUGIN_STACKLEAK = whenAtLeast "4.20" yes; # A port of the PaX stackleak plugin
+  GCC_PLUGIN_RANDSTRUCT = whenAtLeast "4.13" yes; # A port of the PaX randstruct plugin
+  GCC_PLUGIN_RANDSTRUCT_PERFORMANCE = whenAtLeast "4.13" yes;
+
+  # Disable various dangerous settings
+  ACPI_CUSTOM_METHOD = no; # Allows writing directly to physical memory
+  PROC_KCORE         = no; # Exposes kernel text image layout
+  INET_DIAG          = no; # Has been used for heap based attacks in the past
+
+  # Use -fstack-protector-strong (gcc 4.9+) for best stack canary coverage.
+  CC_STACKPROTECTOR_REGULAR = whenOlder "4.18" no;
+  CC_STACKPROTECTOR_STRONG  = whenOlder "4.18" yes;
+
+}