345e0e6794
Implies that SELinux can no longer be disabled at runtime (only at boot time, via selinux=0). See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=dd0859dccbe291cf8179a96390f5c0e45cb9af1d
100 lines
2.8 KiB
Nix
100 lines
2.8 KiB
Nix
# 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;
|
|
|
|
assert (versionAtLeast version "4.9");
|
|
|
|
''
|
|
# Report BUG() conditions and kill the offending process.
|
|
BUG y
|
|
|
|
${optionalString (stdenv.system == "x86_64-linux") ''
|
|
DEFAULT_MMAP_MIN_ADDR 65536 # Prevent allocation of first 64K of memory
|
|
|
|
# Reduce attack surface by disabling various emulations
|
|
IA32_EMULATION n
|
|
X86_X32 n
|
|
MODIFY_LDT_SYSCALL? n
|
|
|
|
VMAP_STACK y # Catch kernel stack overflows
|
|
|
|
# Randomize position of kernel and memory.
|
|
RANDOMIZE_BASE y
|
|
RANDOMIZE_MEMORY y
|
|
|
|
# Disable legacy virtual syscalls by default (modern glibc use vDSO instead).
|
|
#
|
|
# Note that the vanilla default is to *emulate* the legacy vsyscall mechanism,
|
|
# which is supposed to be safer than the native variant (wrt. ret2libc), so
|
|
# disabling it mainly helps reduce surface.
|
|
LEGACY_VSYSCALL_NONE y
|
|
''}
|
|
|
|
# Safer page access permissions (wrt. code injection). Default on >=4.11.
|
|
${optionalString (versionOlder version "4.11") ''
|
|
DEBUG_RODATA y
|
|
DEBUG_SET_MODULE_RONX y
|
|
''}
|
|
|
|
# Mark LSM hooks read-only after init. Conflicts with SECURITY_SELINUX_DISABLE
|
|
# (disabling SELinux at runtime); hence, SELinux can only be disabled at boot
|
|
# via the selinux=0 boot parameter.
|
|
${optionalString (versionAtLeast version "4.12") ''
|
|
SECURITY_SELINUX_DISABLE n
|
|
SECURITY_WRITABLE_HOOKS n
|
|
''}
|
|
|
|
DEBUG_WX y # boot-time warning on RWX mappings
|
|
|
|
# Stricter /dev/mem
|
|
STRICT_DEVMEM y
|
|
IO_STRICT_DEVMEM y
|
|
|
|
# Perform additional validation of commonly targeted structures.
|
|
DEBUG_CREDENTIALS y
|
|
DEBUG_NOTIFIERS y
|
|
DEBUG_LIST y
|
|
DEBUG_SG y
|
|
SCHED_STACK_END_CHECK y
|
|
BUG_ON_DATA_CORRUPTION y
|
|
|
|
# Perform usercopy bounds checking.
|
|
HARDENED_USERCOPY y
|
|
|
|
# Randomize allocator freelists.
|
|
SLAB_FREELIST_RANDOM y
|
|
|
|
# Wipe higher-level memory allocations on free() with page_poison=1
|
|
PAGE_POISONING y
|
|
PAGE_POISONING_NO_SANITY y
|
|
PAGE_POISONING_ZERO y
|
|
|
|
# Reboot devices immediately if kernel experiences an Oops.
|
|
PANIC_ON_OOPS y
|
|
PANIC_TIMEOUT -1
|
|
|
|
GCC_PLUGINS y # Enable gcc plugin options
|
|
|
|
${optionalString (versionAtLeast version "4.11") ''
|
|
GCC_PLUGIN_STRUCTLEAK y # A port of the PaX structleak plugin
|
|
''}
|
|
|
|
# Disable various dangerous settings
|
|
ACPI_CUSTOM_METHOD n # Allows writing directly to physical memory
|
|
PROC_KCORE n # Exposes kernel text image layout
|
|
INET_DIAG n # 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 n
|
|
CC_STACKPROTECTOR_STRONG y
|
|
''
|