4 # This tool helps me to check Linux kernel options against
5 # my security hardening preferences for X86_64, ARM64, X86_32, and ARM.
6 # Let the computers do their job!
8 # Author: Alexander Popov <alex.popov@linux.com>
10 # Please don't cry if my Python code looks like C.
13 # N.B Hardening command line parameters:
14 # page_alloc.shuffle=1
15 # iommu=force (does it help against DMA attacks?)
18 # slub_debug=FZ (slow)
19 # init_on_alloc=1 (since v5.3)
20 # init_on_free=1 (since v5.3, otherwise slub_debug=P and page_poison=1)
22 # debugfs=no-mount (or off if possible)
24 # Mitigations of CPU vulnerabilities:
26 # mitigations=auto,nosmt (nosmt is slow)
29 # spec_store_bypass_disable=on
31 # l1d_flush=on (a part of the l1tf option)
42 # sysrq_always_enabled
47 # Hardware tag-based KASAN with arm64 Memory Tagging Extension (MTE):
49 # kasan.stacktrace=off
52 # N.B. Hardening sysctls:
53 # kernel.kptr_restrict=2 (or 1?)
54 # kernel.dmesg_restrict=1 (also see the kconfig option)
55 # kernel.perf_event_paranoid=3
56 # kernel.kexec_load_disabled=1
57 # kernel.yama.ptrace_scope=3
58 # user.max_user_namespaces=0
59 # what about bpf_jit_enable?
60 # kernel.unprivileged_bpf_disabled=1
61 # net.core.bpf_jit_harden=2
62 # vm.unprivileged_userfaultfd=0
63 # (at first, it disabled unprivileged userfaultfd,
64 # and since v5.11 it enables unprivileged userfaultfd for user-mode only)
65 # dev.tty.ldisc_autoload=0
66 # fs.protected_symlinks=1
67 # fs.protected_hardlinks=1
68 # fs.protected_fifos=2
69 # fs.protected_regular=2
71 # kernel.modules_disabled=1
72 # kernel.randomize_va_space = 2
75 # pylint: disable=missing-module-docstring,missing-class-docstring,missing-function-docstring
76 # pylint: disable=line-too-long,invalid-name,too-many-branches,too-many-statements
80 from argparse import ArgumentParser
81 from collections import OrderedDict
84 from .__about__ import __version__
86 SIMPLE_OPTION_TYPES = ('kconfig', 'version', 'cmdline')
89 # Constructor without the 'expected' parameter is for option presence checks (any value is OK)
90 def __init__(self, reason, decision, name, expected=None):
91 assert(reason and decision and name), \
92 'invalid {} check for "{}"'.format(self.__class__.__name__, name)
94 self.expected = expected
95 self.decision = decision
105 # handle the option presence check
106 if self.expected is None:
107 if self.state is None:
108 self.result = 'FAIL: not present'
110 self.result = 'OK: is present'
113 # handle the option value check
114 if self.expected == self.state:
116 elif self.state is None:
117 if self.expected == 'is not set':
118 self.result = 'OK: not found'
120 self.result = 'FAIL: not found'
122 self.result = 'FAIL: "' + self.state + '"'
124 def table_print(self, _mode, with_results):
125 if self.expected is None:
128 expected = self.expected
129 print('{:<40}|{:^7}|{:^12}|{:^10}|{:^18}'.format(self.name, self.type, expected, self.decision, self.reason), end='')
131 print('| {}'.format(self.result), end='')
133 def json_dump(self, with_results):
134 dump = [self.name, self.type, self.expected, self.decision, self.reason]
136 dump.append(self.result)
140 class KconfigCheck(OptCheck):
141 def __init__(self, *args, **kwargs):
142 super().__init__(*args, **kwargs)
143 self.name = 'CONFIG_' + self.name
150 class CmdlineCheck(OptCheck):
157 def __init__(self, ver_expected):
158 self.ver_expected = ver_expected
167 if self.ver[0] > self.ver_expected[0]:
168 self.result = 'OK: version >= ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
170 if self.ver[0] < self.ver_expected[0]:
171 self.result = 'FAIL: version < ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
173 if self.ver[1] >= self.ver_expected[1]:
174 self.result = 'OK: version >= ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
176 self.result = 'FAIL: version < ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
178 def table_print(self, _mode, with_results):
179 ver_req = 'kernel version >= ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
180 print('{:<91}'.format(ver_req), end='')
182 print('| {}'.format(self.result), end='')
185 class ComplexOptCheck:
186 def __init__(self, *opts):
189 'empty {} check'.format(self.__class__.__name__)
190 assert(len(self.opts) != 1), \
191 'useless {} check: {}'.format(self.__class__.__name__, opts)
192 assert(isinstance(opts[0], (KconfigCheck, CmdlineCheck))), \
193 'invalid {} check: {}'.format(self.__class__.__name__, opts)
202 return self.opts[0].name
206 return self.opts[0].expected
208 def table_print(self, mode, with_results):
209 if mode == 'verbose':
210 print(' {:87}'.format('<<< ' + self.__class__.__name__ + ' >>>'), end='')
212 print('| {}'.format(self.result), end='')
215 o.table_print(mode, with_results)
218 o.table_print(mode, False)
220 print('| {}'.format(self.result), end='')
222 def json_dump(self, with_results):
223 dump = self.opts[0].json_dump(False)
225 dump.append(self.result)
229 class OR(ComplexOptCheck):
230 # self.opts[0] is the option that this OR-check is about.
232 # OR(<X_is_hardened>, <X_is_disabled>)
233 # OR(<X_is_hardened>, <old_X_is_hardened>)
235 for i, opt in enumerate(self.opts):
237 if opt.result.startswith('OK'):
238 self.result = opt.result
239 # Add more info for additional checks:
241 if opt.result == 'OK':
242 self.result = 'OK: {} "{}"'.format(opt.name, opt.expected)
243 elif opt.result == 'OK: not found':
244 self.result = 'OK: {} not found'.format(opt.name)
245 elif opt.result == 'OK: is present':
246 self.result = 'OK: {} is present'.format(opt.name)
248 # VersionCheck provides enough info
249 assert(opt.result.startswith('OK: version')), \
250 'unexpected OK description "{}"'.format(opt.result)
252 self.result = self.opts[0].result
255 class AND(ComplexOptCheck):
256 # self.opts[0] is the option that this AND-check is about.
258 # AND(<suboption>, <main_option>)
259 # Suboption is not checked if checking of the main_option is failed.
260 # AND(<X_is_disabled>, <old_X_is_disabled>)
262 for i, opt in reversed(list(enumerate(self.opts))):
265 self.result = opt.result
267 if not opt.result.startswith('OK'):
268 # This FAIL is caused by additional checks,
269 # and not by the main option that this AND-check is about.
270 # Describe the reason of the FAIL.
271 if opt.result.startswith('FAIL: \"') or opt.result == 'FAIL: not found':
272 self.result = 'FAIL: {} not "{}"'.format(opt.name, opt.expected)
273 elif opt.result == 'FAIL: not present':
274 self.result = 'FAIL: {} not present'.format(opt.name)
276 # VersionCheck provides enough info
277 self.result = opt.result
278 assert(opt.result.startswith('FAIL: version')), \
279 'unexpected FAIL description "{}"'.format(opt.result)
283 def detect_arch(fname, archs):
284 with open(fname, 'r') as f:
285 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
287 for line in f.readlines():
288 if arch_pattern.match(line):
289 option, _ = line[7:].split('=', 1)
294 return None, 'more than one supported architecture is detected'
296 return None, 'failed to detect architecture'
300 def detect_version(fname):
301 with open(fname, 'r') as f:
302 ver_pattern = re.compile("# Linux/.* Kernel Configuration")
303 for line in f.readlines():
304 if ver_pattern.match(line):
308 ver_numbers = ver_str.split('.')
309 if len(ver_numbers) < 3 or not ver_numbers[0].isdigit() or not ver_numbers[1].isdigit():
310 msg = 'failed to parse the version "' + ver_str + '"'
312 return (int(ver_numbers[0]), int(ver_numbers[1])), None
313 return None, 'no kernel version detected'
316 def add_kconfig_checks(l, arch):
317 # Calling the KconfigCheck class constructor:
318 # KconfigCheck(reason, decision, name, expected)
320 modules_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'MODULES', 'is not set')
321 devmem_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'DEVMEM', 'is not set') # refers to LOCKDOWN
322 bpf_syscall_not_set = KconfigCheck('cut_attack_surface', 'lockdown', 'BPF_SYSCALL', 'is not set') # refers to LOCKDOWN
323 efi_not_set = KconfigCheck('cut_attack_surface', 'my', 'EFI', 'is not set')
325 # 'self_protection', 'defconfig'
326 l += [KconfigCheck('self_protection', 'defconfig', 'BUG', 'y')]
327 l += [KconfigCheck('self_protection', 'defconfig', 'SLUB_DEBUG', 'y')]
328 l += [KconfigCheck('self_protection', 'defconfig', 'GCC_PLUGINS', 'y')]
329 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR', 'y'),
330 KconfigCheck('self_protection', 'defconfig', 'CC_STACKPROTECTOR', 'y'))]
331 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR_STRONG', 'y'),
332 KconfigCheck('self_protection', 'defconfig', 'CC_STACKPROTECTOR_STRONG', 'y'))]
333 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STRICT_KERNEL_RWX', 'y'),
334 KconfigCheck('self_protection', 'defconfig', 'DEBUG_RODATA', 'y'))] # before v4.11
335 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STRICT_MODULE_RWX', 'y'),
336 KconfigCheck('self_protection', 'defconfig', 'DEBUG_SET_MODULE_RONX', 'y'),
337 modules_not_set)] # DEBUG_SET_MODULE_RONX was before v4.11
338 l += [OR(KconfigCheck('self_protection', 'defconfig', 'REFCOUNT_FULL', 'y'),
339 VersionCheck((5, 5)))] # REFCOUNT_FULL is enabled by default since v5.5
340 l += [KconfigCheck('self_protection', 'defconfig', 'THREAD_INFO_IN_TASK', 'y')]
341 iommu_support_is_set = KconfigCheck('self_protection', 'defconfig', 'IOMMU_SUPPORT', 'y')
342 l += [iommu_support_is_set] # is needed for mitigating DMA attacks
343 if arch in ('X86_64', 'ARM64', 'X86_32'):
344 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_BASE', 'y')]
345 if arch in ('X86_64', 'ARM64'):
346 l += [KconfigCheck('self_protection', 'defconfig', 'VMAP_STACK', 'y')]
347 if arch in ('X86_64', 'X86_32'):
348 l += [KconfigCheck('self_protection', 'defconfig', 'MICROCODE', 'y')] # is needed for mitigating CPU bugs
349 l += [KconfigCheck('self_protection', 'defconfig', 'RETPOLINE', 'y')]
350 l += [KconfigCheck('self_protection', 'defconfig', 'X86_SMAP', 'y')]
351 l += [KconfigCheck('self_protection', 'defconfig', 'SYN_COOKIES', 'y')] # another reason?
352 l += [OR(KconfigCheck('self_protection', 'defconfig', 'X86_UMIP', 'y'),
353 KconfigCheck('self_protection', 'defconfig', 'X86_INTEL_UMIP', 'y'))]
354 if arch in ('ARM64', 'ARM'):
355 l += [KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR_PER_TASK', 'y')]
357 l += [KconfigCheck('self_protection', 'defconfig', 'PAGE_TABLE_ISOLATION', 'y')]
358 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_MEMORY', 'y')]
359 l += [AND(KconfigCheck('self_protection', 'defconfig', 'INTEL_IOMMU', 'y'),
360 iommu_support_is_set)]
361 l += [AND(KconfigCheck('self_protection', 'defconfig', 'AMD_IOMMU', 'y'),
362 iommu_support_is_set)]
364 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_PAN', 'y')]
365 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_EPAN', 'y')]
366 l += [KconfigCheck('self_protection', 'defconfig', 'UNMAP_KERNEL_AT_EL0', 'y')]
367 l += [OR(KconfigCheck('self_protection', 'defconfig', 'HARDEN_EL2_VECTORS', 'y'),
368 AND(KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_BASE', 'y'),
369 VersionCheck((5, 9))))] # HARDEN_EL2_VECTORS was included in RANDOMIZE_BASE in v5.9
370 l += [KconfigCheck('self_protection', 'defconfig', 'RODATA_FULL_DEFAULT_ENABLED', 'y')]
371 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_PTR_AUTH_KERNEL', 'y')]
372 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_BTI_KERNEL', 'y')]
373 l += [OR(KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_PREDICTOR', 'y'),
374 VersionCheck((5, 10)))] # HARDEN_BRANCH_PREDICTOR is enabled by default since v5.10
375 l += [KconfigCheck('self_protection', 'defconfig', 'MITIGATE_SPECTRE_BRANCH_HISTORY', 'y')]
376 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_MTE', 'y')]
377 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_MODULE_REGION_FULL', 'y')]
379 l += [KconfigCheck('self_protection', 'defconfig', 'CPU_SW_DOMAIN_PAN', 'y')]
380 l += [KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_PREDICTOR', 'y')]
381 l += [KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_HISTORY', 'y')]
383 # 'self_protection', 'kspp'
384 l += [KconfigCheck('self_protection', 'kspp', 'SECURITY_DMESG_RESTRICT', 'y')]
385 l += [KconfigCheck('self_protection', 'kspp', 'BUG_ON_DATA_CORRUPTION', 'y')]
386 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_WX', 'y')]
387 l += [KconfigCheck('self_protection', 'kspp', 'SCHED_STACK_END_CHECK', 'y')]
388 l += [KconfigCheck('self_protection', 'kspp', 'SLAB_FREELIST_HARDENED', 'y')]
389 l += [KconfigCheck('self_protection', 'kspp', 'SLAB_FREELIST_RANDOM', 'y')]
390 l += [KconfigCheck('self_protection', 'kspp', 'SHUFFLE_PAGE_ALLOCATOR', 'y')]
391 l += [KconfigCheck('self_protection', 'kspp', 'FORTIFY_SOURCE', 'y')]
392 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_LIST', 'y')]
393 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_SG', 'y')]
394 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_CREDENTIALS', 'y')]
395 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_NOTIFIERS', 'y')]
396 l += [KconfigCheck('self_protection', 'kspp', 'INIT_ON_ALLOC_DEFAULT_ON', 'y')]
397 l += [KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_LATENT_ENTROPY', 'y')]
398 l += [KconfigCheck('self_protection', 'kspp', 'KFENCE', 'y')]
399 l += [KconfigCheck('self_protection', 'kspp', 'WERROR', 'y')]
400 l += [KconfigCheck('self_protection', 'kspp', 'IOMMU_DEFAULT_DMA_STRICT', 'y')]
401 l += [KconfigCheck('self_protection', 'kspp', 'ZERO_CALL_USED_REGS', 'y')]
402 randstruct_is_set = KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_RANDSTRUCT', 'y')
403 l += [randstruct_is_set]
404 hardened_usercopy_is_set = KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY', 'y')
405 l += [hardened_usercopy_is_set]
406 l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_FALLBACK', 'is not set'),
407 hardened_usercopy_is_set)]
408 l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_PAGESPAN', 'is not set'),
409 hardened_usercopy_is_set)]
410 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG', 'y'),
412 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_ALL', 'y'),
414 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_SHA512', 'y'),
416 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_FORCE', 'y'),
417 modules_not_set)] # refers to LOCKDOWN
418 l += [OR(KconfigCheck('self_protection', 'kspp', 'INIT_STACK_ALL_ZERO', 'y'),
419 KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_STRUCTLEAK_BYREF_ALL', 'y'))]
420 l += [OR(KconfigCheck('self_protection', 'kspp', 'INIT_ON_FREE_DEFAULT_ON', 'y'),
421 KconfigCheck('self_protection', 'kspp', 'PAGE_POISONING_ZERO', 'y'))]
422 # CONFIG_INIT_ON_FREE_DEFAULT_ON was added in v5.3.
423 # CONFIG_PAGE_POISONING_ZERO was removed in v5.11.
424 # Starting from v5.11 CONFIG_PAGE_POISONING unconditionally checks
425 # the 0xAA poison pattern on allocation.
426 # That brings higher performance penalty.
427 if arch in ('X86_64', 'ARM64', 'X86_32'):
428 stackleak_is_set = KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_STACKLEAK', 'y')
429 l += [stackleak_is_set]
430 l += [OR(KconfigCheck('self_protection', 'kspp', 'RANDOMIZE_KSTACK_OFFSET_DEFAULT', 'y'),
431 CmdlineCheck('self_protection', 'kspp', 'randomize_kstack_offset', '1'))]
432 if arch in ('X86_64', 'X86_32'):
433 l += [KconfigCheck('self_protection', 'kspp', 'SCHED_CORE', 'y')]
434 l += [KconfigCheck('self_protection', 'kspp', 'DEFAULT_MMAP_MIN_ADDR', '65536')]
435 if arch in ('ARM64', 'ARM'):
436 l += [KconfigCheck('self_protection', 'kspp', 'DEFAULT_MMAP_MIN_ADDR', '32768')]
437 l += [KconfigCheck('self_protection', 'kspp', 'SYN_COOKIES', 'y')] # another reason?
439 l += [KconfigCheck('self_protection', 'kspp', 'ARM64_SW_TTBR0_PAN', 'y')]
441 l += [KconfigCheck('self_protection', 'kspp', 'PAGE_TABLE_ISOLATION', 'y')]
442 l += [KconfigCheck('self_protection', 'kspp', 'HIGHMEM64G', 'y')]
443 l += [KconfigCheck('self_protection', 'kspp', 'X86_PAE', 'y')]
445 # 'self_protection', 'maintainer'
446 ubsan_bounds_is_set = KconfigCheck('self_protection', 'maintainer', 'UBSAN_BOUNDS', 'y') # only array index bounds checking
447 l += [ubsan_bounds_is_set] # recommended by Kees Cook in /issues/53
448 if arch in ('X86_64', 'ARM64', 'X86_32'): # ARCH_HAS_UBSAN_SANITIZE_ALL is not enabled for ARM
449 l += [AND(KconfigCheck('self_protection', 'maintainer', 'UBSAN_SANITIZE_ALL', 'y'),
450 ubsan_bounds_is_set)] # recommended by Kees Cook in /issues/53
451 l += [AND(KconfigCheck('self_protection', 'maintainer', 'UBSAN_TRAP', 'y'),
452 ubsan_bounds_is_set)] # recommended by Kees Cook in /issues/53
454 # 'self_protection', 'clipos'
455 l += [KconfigCheck('self_protection', 'clipos', 'DEBUG_VIRTUAL', 'y')]
456 l += [KconfigCheck('self_protection', 'clipos', 'STATIC_USERMODEHELPER', 'y')] # needs userspace support
457 l += [OR(KconfigCheck('self_protection', 'clipos', 'EFI_DISABLE_PCI_DMA', 'y'),
459 l += [OR(KconfigCheck('self_protection', 'clipos', 'SLAB_MERGE_DEFAULT', 'is not set'),
460 CmdlineCheck('self_protection', 'kspp', 'slab_nomerge'))] # option presence check
461 l += [KconfigCheck('self_protection', 'clipos', 'RANDOM_TRUST_BOOTLOADER', 'is not set')]
462 l += [KconfigCheck('self_protection', 'clipos', 'RANDOM_TRUST_CPU', 'is not set')]
463 l += [AND(KconfigCheck('self_protection', 'clipos', 'GCC_PLUGIN_RANDSTRUCT_PERFORMANCE', 'is not set'),
465 if arch in ('X86_64', 'ARM64', 'X86_32'):
466 l += [AND(KconfigCheck('self_protection', 'clipos', 'STACKLEAK_METRICS', 'is not set'),
468 l += [AND(KconfigCheck('self_protection', 'clipos', 'STACKLEAK_RUNTIME_DISABLE', 'is not set'),
470 if arch in ('X86_64', 'X86_32'):
471 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU_DEFAULT_ON', 'y'),
472 iommu_support_is_set)]
474 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU_SVM', 'y'),
475 iommu_support_is_set)]
477 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU', 'y'),
478 iommu_support_is_set)]
480 # 'self_protection', 'my'
481 l += [OR(KconfigCheck('self_protection', 'my', 'RESET_ATTACK_MITIGATION', 'y'),
482 efi_not_set)] # needs userspace support (systemd)
484 l += [KconfigCheck('self_protection', 'my', 'SLS', 'y')] # vs CVE-2021-26341 in Straight-Line-Speculation
485 l += [AND(KconfigCheck('self_protection', 'my', 'AMD_IOMMU_V2', 'y'),
486 iommu_support_is_set)]
488 l += [KconfigCheck('self_protection', 'my', 'SHADOW_CALL_STACK', 'y')] # depends on clang, maybe it's alternative to STACKPROTECTOR_STRONG
489 l += [KconfigCheck('self_protection', 'my', 'KASAN_HW_TAGS', 'y')]
490 cfi_clang_is_set = KconfigCheck('self_protection', 'my', 'CFI_CLANG', 'y')
491 l += [cfi_clang_is_set]
492 l += [AND(KconfigCheck('self_protection', 'my', 'CFI_PERMISSIVE', 'is not set'),
496 if arch in ('X86_64', 'ARM64', 'X86_32'):
497 l += [KconfigCheck('security_policy', 'defconfig', 'SECURITY', 'y')] # and choose your favourite LSM
499 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY', 'y')] # and choose your favourite LSM
500 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY_YAMA', 'y')]
501 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY_SELINUX_DISABLE', 'is not set')]
502 l += [KconfigCheck('security_policy', 'clipos', 'SECURITY_LOCKDOWN_LSM', 'y')]
503 l += [KconfigCheck('security_policy', 'clipos', 'SECURITY_LOCKDOWN_LSM_EARLY', 'y')]
504 l += [KconfigCheck('security_policy', 'clipos', 'LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY', 'y')]
505 l += [KconfigCheck('security_policy', 'my', 'SECURITY_WRITABLE_HOOKS', 'is not set')] # refers to SECURITY_SELINUX_DISABLE
506 l += [KconfigCheck('security_policy', 'my', 'SECURITY_SAFESETID', 'y')]
507 loadpin_is_set = KconfigCheck('security_policy', 'my', 'SECURITY_LOADPIN', 'y')
508 l += [loadpin_is_set] # needs userspace support
509 l += [AND(KconfigCheck('security_policy', 'my', 'SECURITY_LOADPIN_ENFORCE', 'y'),
512 # 'cut_attack_surface', 'defconfig'
513 l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'BPF_UNPRIV_DEFAULT_OFF', 'y'),
514 bpf_syscall_not_set)] # see unprivileged_bpf_disabled
515 l += [KconfigCheck('cut_attack_surface', 'defconfig', 'SECCOMP', 'y')]
516 l += [KconfigCheck('cut_attack_surface', 'defconfig', 'SECCOMP_FILTER', 'y')]
517 if arch in ('X86_64', 'ARM64', 'X86_32'):
518 l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'STRICT_DEVMEM', 'y'),
519 devmem_not_set)] # refers to LOCKDOWN
521 # 'cut_attack_surface', 'kspp'
522 l += [KconfigCheck('cut_attack_surface', 'kspp', 'ACPI_CUSTOM_METHOD', 'is not set')] # refers to LOCKDOWN
523 l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_BRK', 'is not set')]
524 l += [KconfigCheck('cut_attack_surface', 'kspp', 'DEVKMEM', 'is not set')] # refers to LOCKDOWN
525 l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_VDSO', 'is not set')]
526 l += [KconfigCheck('cut_attack_surface', 'kspp', 'BINFMT_MISC', 'is not set')]
527 l += [KconfigCheck('cut_attack_surface', 'kspp', 'INET_DIAG', 'is not set')]
528 l += [KconfigCheck('cut_attack_surface', 'kspp', 'KEXEC', 'is not set')] # refers to LOCKDOWN
529 l += [KconfigCheck('cut_attack_surface', 'kspp', 'PROC_KCORE', 'is not set')] # refers to LOCKDOWN
530 l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_PTYS', 'is not set')]
531 l += [KconfigCheck('cut_attack_surface', 'kspp', 'HIBERNATION', 'is not set')] # refers to LOCKDOWN
532 l += [KconfigCheck('cut_attack_surface', 'kspp', 'IA32_EMULATION', 'is not set')]
533 l += [KconfigCheck('cut_attack_surface', 'kspp', 'X86_X32', 'is not set')]
534 l += [KconfigCheck('cut_attack_surface', 'kspp', 'MODIFY_LDT_SYSCALL', 'is not set')]
535 l += [KconfigCheck('cut_attack_surface', 'kspp', 'OABI_COMPAT', 'is not set')]
536 l += [KconfigCheck('cut_attack_surface', 'kspp', 'X86_MSR', 'is not set')] # refers to LOCKDOWN
537 l += [modules_not_set]
538 l += [devmem_not_set]
539 l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'IO_STRICT_DEVMEM', 'y'),
540 devmem_not_set)] # refers to LOCKDOWN
542 l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'STRICT_DEVMEM', 'y'),
543 devmem_not_set)] # refers to LOCKDOWN
545 l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_VSYSCALL_NONE', 'y')] # 'vsyscall=none'
547 # 'cut_attack_surface', 'grsec'
548 l += [KconfigCheck('cut_attack_surface', 'grsec', 'ZSMALLOC_STAT', 'is not set')]
549 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PAGE_OWNER', 'is not set')]
550 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEBUG_KMEMLEAK', 'is not set')]
551 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BINFMT_AOUT', 'is not set')]
552 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KPROBE_EVENTS', 'is not set')]
553 l += [KconfigCheck('cut_attack_surface', 'grsec', 'UPROBE_EVENTS', 'is not set')]
554 l += [KconfigCheck('cut_attack_surface', 'grsec', 'GENERIC_TRACER', 'is not set')] # refers to LOCKDOWN
555 l += [KconfigCheck('cut_attack_surface', 'grsec', 'FUNCTION_TRACER', 'is not set')]
556 l += [KconfigCheck('cut_attack_surface', 'grsec', 'STACK_TRACER', 'is not set')]
557 l += [KconfigCheck('cut_attack_surface', 'grsec', 'HIST_TRIGGERS', 'is not set')]
558 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BLK_DEV_IO_TRACE', 'is not set')]
559 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROC_VMCORE', 'is not set')]
560 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROC_PAGE_MONITOR', 'is not set')]
561 l += [KconfigCheck('cut_attack_surface', 'grsec', 'USELIB', 'is not set')]
562 l += [KconfigCheck('cut_attack_surface', 'grsec', 'CHECKPOINT_RESTORE', 'is not set')]
563 l += [KconfigCheck('cut_attack_surface', 'grsec', 'USERFAULTFD', 'is not set')]
564 l += [KconfigCheck('cut_attack_surface', 'grsec', 'HWPOISON_INJECT', 'is not set')]
565 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MEM_SOFT_DIRTY', 'is not set')]
566 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEVPORT', 'is not set')] # refers to LOCKDOWN
567 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEBUG_FS', 'is not set')] # refers to LOCKDOWN
568 l += [KconfigCheck('cut_attack_surface', 'grsec', 'NOTIFIER_ERROR_INJECTION', 'is not set')]
569 l += [KconfigCheck('cut_attack_surface', 'grsec', 'FAIL_FUTEX', 'is not set')]
570 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PUNIT_ATOM_DEBUG', 'is not set')]
571 l += [KconfigCheck('cut_attack_surface', 'grsec', 'ACPI_CONFIGFS', 'is not set')]
572 l += [KconfigCheck('cut_attack_surface', 'grsec', 'EDAC_DEBUG', 'is not set')]
573 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DRM_I915_DEBUG', 'is not set')]
574 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BCACHE_CLOSURES_DEBUG', 'is not set')]
575 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DVB_C8SECTPFE', 'is not set')]
576 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MTD_SLRAM', 'is not set')]
577 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MTD_PHRAM', 'is not set')]
578 l += [KconfigCheck('cut_attack_surface', 'grsec', 'IO_URING', 'is not set')]
579 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KCMP', 'is not set')]
580 l += [KconfigCheck('cut_attack_surface', 'grsec', 'RSEQ', 'is not set')]
581 l += [KconfigCheck('cut_attack_surface', 'grsec', 'LATENCYTOP', 'is not set')]
582 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KCOV', 'is not set')]
583 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROVIDE_OHCI1394_DMA_INIT', 'is not set')]
584 l += [KconfigCheck('cut_attack_surface', 'grsec', 'SUNRPC_DEBUG', 'is not set')]
585 l += [AND(KconfigCheck('cut_attack_surface', 'grsec', 'PTDUMP_DEBUGFS', 'is not set'),
586 KconfigCheck('cut_attack_surface', 'grsec', 'X86_PTDUMP', 'is not set'))]
588 # 'cut_attack_surface', 'maintainer'
589 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'DRM_LEGACY', 'is not set')] # recommended by Daniel Vetter in /issues/38
590 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'FB', 'is not set')] # recommended by Daniel Vetter in /issues/38
591 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'VT', 'is not set')] # recommended by Daniel Vetter in /issues/38
592 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'BLK_DEV_FD', 'is not set')] # recommended by Denis Efremov in /pull/54
593 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'BLK_DEV_FD_RAWCMD', 'is not set')] # recommended by Denis Efremov in /pull/62
595 # 'cut_attack_surface', 'grapheneos'
596 l += [KconfigCheck('cut_attack_surface', 'grapheneos', 'AIO', 'is not set')]
598 # 'cut_attack_surface', 'clipos'
599 l += [KconfigCheck('cut_attack_surface', 'clipos', 'STAGING', 'is not set')]
600 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KSM', 'is not set')] # to prevent FLUSH+RELOAD attack
601 # l += [KconfigCheck('cut_attack_surface', 'clipos', 'IKCONFIG', 'is not set')] # no, IKCONFIG is needed for this check :)
602 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KALLSYMS', 'is not set')]
603 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_VSYSCALL_EMULATION', 'is not set')]
604 l += [KconfigCheck('cut_attack_surface', 'clipos', 'MAGIC_SYSRQ', 'is not set')]
605 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KEXEC_FILE', 'is not set')] # refers to LOCKDOWN (permissive)
606 l += [KconfigCheck('cut_attack_surface', 'clipos', 'USER_NS', 'is not set')] # user.max_user_namespaces=0
607 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_CPUID', 'is not set')]
608 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_IOPL_IOPERM', 'is not set')] # refers to LOCKDOWN
609 l += [KconfigCheck('cut_attack_surface', 'clipos', 'ACPI_TABLE_UPGRADE', 'is not set')] # refers to LOCKDOWN
610 l += [KconfigCheck('cut_attack_surface', 'clipos', 'EFI_CUSTOM_SSDT_OVERLAYS', 'is not set')]
611 l += [AND(KconfigCheck('cut_attack_surface', 'clipos', 'LDISC_AUTOLOAD', 'is not set'),
612 KconfigCheck('cut_attack_surface', 'clipos', 'LDISC_AUTOLOAD'))] # option presence check
613 if arch in ('X86_64', 'X86_32'):
614 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_INTEL_TSX_MODE_OFF', 'y')] # tsx=off
616 # 'cut_attack_surface', 'lockdown'
617 l += [bpf_syscall_not_set] # refers to LOCKDOWN
618 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'EFI_TEST', 'is not set')] # refers to LOCKDOWN
619 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'MMIOTRACE_TEST', 'is not set')] # refers to LOCKDOWN
620 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'KPROBES', 'is not set')] # refers to LOCKDOWN
622 # 'cut_attack_surface', 'my'
623 l += [OR(KconfigCheck('cut_attack_surface', 'my', 'TRIM_UNUSED_KSYMS', 'y'),
625 l += [KconfigCheck('cut_attack_surface', 'my', 'MMIOTRACE', 'is not set')] # refers to LOCKDOWN (permissive)
626 l += [KconfigCheck('cut_attack_surface', 'my', 'LIVEPATCH', 'is not set')]
627 l += [KconfigCheck('cut_attack_surface', 'my', 'IP_DCCP', 'is not set')]
628 l += [KconfigCheck('cut_attack_surface', 'my', 'IP_SCTP', 'is not set')]
629 l += [KconfigCheck('cut_attack_surface', 'my', 'FTRACE', 'is not set')] # refers to LOCKDOWN
630 l += [KconfigCheck('cut_attack_surface', 'my', 'VIDEO_VIVID', 'is not set')]
631 l += [KconfigCheck('cut_attack_surface', 'my', 'INPUT_EVBUG', 'is not set')] # Can be used as a keylogger
632 l += [KconfigCheck('cut_attack_surface', 'my', 'KGDB', 'is not set')]
635 if arch in ('X86_64', 'ARM64', 'X86_32'):
636 l += [KconfigCheck('harden_userspace', 'defconfig', 'INTEGRITY', 'y')]
638 l += [KconfigCheck('harden_userspace', 'my', 'INTEGRITY', 'y')]
639 if arch in ('ARM', 'X86_32'):
640 l += [KconfigCheck('harden_userspace', 'defconfig', 'VMSPLIT_3G', 'y')]
641 if arch in ('X86_64', 'ARM64'):
642 l += [KconfigCheck('harden_userspace', 'clipos', 'ARCH_MMAP_RND_BITS', '32')]
643 if arch in ('X86_32', 'ARM'):
644 l += [KconfigCheck('harden_userspace', 'my', 'ARCH_MMAP_RND_BITS', '16')]
646 # l += [KconfigCheck('feature_test', 'my', 'LKDTM', 'm')] # only for debugging!
649 def add_cmdline_checks(l, arch):
650 # Calling the CmdlineCheck class constructor:
651 # CmdlineCheck(reason, decision, name, expected)
653 if arch in ('X86_64', 'X86_32'):
654 l += [CmdlineCheck('self_protection', 'kspp', 'pti', 'on')]
658 def print_unknown_options(checklist, parsed_options):
662 if o1.type != 'complex':
663 known_options.append(o1.name)
666 if o2.type != 'complex':
667 if hasattr(o2, 'name'):
668 known_options.append(o2.name)
671 assert(o3.type != 'complex'), \
672 'unexpected ComplexOptCheck inside {}'.format(o2.name)
673 if hasattr(o3, 'name'):
674 known_options.append(o3.name)
676 for option, value in parsed_options.items():
677 if option not in known_options:
678 print('[?] No check for option {} ({})'.format(option, value))
681 def print_checklist(mode, checklist, with_results):
685 output.append(o.json_dump(with_results))
686 print(json.dumps(output))
693 print('=' * sep_line_len)
694 print('{:^40}|{:^7}|{:^12}|{:^10}|{:^18}'.format('option name', 'type', 'desired val', 'decision', 'reason'), end='')
696 print('| {}'.format('check result'), end='')
698 print('=' * sep_line_len)
701 for opt in checklist:
703 if mode == 'show_ok':
704 if not opt.result.startswith('OK'):
706 if mode == 'show_fail':
707 if not opt.result.startswith('FAIL'):
709 opt.table_print(mode, with_results)
711 if mode == 'verbose':
712 print('-' * sep_line_len)
717 fail_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
719 ok_count = len(list(filter(lambda opt: opt.result.startswith('OK'), checklist)))
721 if mode == 'show_ok':
722 fail_suppressed = ' (suppressed in output)'
723 if mode == 'show_fail':
724 ok_suppressed = ' (suppressed in output)'
726 print('[+] Config check is finished: \'OK\' - {}{} / \'FAIL\' - {}{}'.format(ok_count, ok_suppressed, fail_count, fail_suppressed))
729 def populate_simple_opt_with_data(opt, data, data_type):
730 assert(opt.type != 'complex'), \
731 'unexpected ComplexOptCheck "{}"'.format(opt.name)
732 assert(opt.type in SIMPLE_OPTION_TYPES), \
733 'invalid opt type "{}"'.format(opt.type)
734 assert(data_type in SIMPLE_OPTION_TYPES), \
735 'invalid data type "{}"'.format(data_type)
737 if data_type != opt.type:
740 if data_type in ('kconfig', 'cmdline'):
741 opt.state = data.get(opt.name, None)
743 assert(data_type == 'version'), \
744 'unexpected data type "{}"'.format(data_type)
748 def populate_opt_with_data(opt, data, data_type):
749 if opt.type == 'complex':
751 if o.type == 'complex':
752 # Recursion for nested ComplexOptCheck objects
753 populate_opt_with_data(o, data, data_type)
755 populate_simple_opt_with_data(o, data, data_type)
757 assert(opt.type in ('kconfig', 'cmdline')), \
758 'bad type "{}" for a simple check'.format(opt.type)
759 populate_simple_opt_with_data(opt, data, data_type)
762 def populate_with_data(checklist, data, data_type):
763 for opt in checklist:
764 populate_opt_with_data(opt, data, data_type)
767 def perform_checks(checklist):
768 for opt in checklist:
772 def parse_kconfig_file(parsed_options, fname):
773 with open(fname, 'r') as f:
774 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
775 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
777 for line in f.readlines():
782 if opt_is_on.match(line):
783 option, value = line.split('=', 1)
784 elif opt_is_off.match(line):
785 option, value = line[2:].split(' ', 1)
786 if value != 'is not set':
787 sys.exit('[!] ERROR: bad disabled kconfig option "{}"'.format(line))
789 if option in parsed_options:
790 sys.exit('[!] ERROR: kconfig option "{}" exists multiple times'.format(line))
793 parsed_options[option] = value
796 def parse_cmdline_file(parsed_options, fname):
797 with open(fname, 'r') as f:
803 sys.exit('[!] ERROR: more than one line in "{}"'.format(fname))
807 name, value = opt.split('=', 1)
810 value = '' # '' is not None
811 parsed_options[name] = value
817 # - reporting about unknown kernel options in the kconfig
818 # - verbose printing of ComplexOptCheck items
819 # * json mode for printing the results in JSON format
820 report_modes = ['verbose', 'json', 'show_ok', 'show_fail']
821 supported_archs = ['X86_64', 'X86_32', 'ARM64', 'ARM']
822 parser = ArgumentParser(prog='kconfig-hardened-check',
823 description='A tool for checking the security hardening options of the Linux kernel')
824 parser.add_argument('--version', action='version', version='%(prog)s ' + __version__)
825 parser.add_argument('-p', '--print', choices=supported_archs,
826 help='print security hardening preferences for the selected architecture')
827 parser.add_argument('-c', '--config',
828 help='check the kernel kconfig file against these preferences')
829 parser.add_argument('-l', '--cmdline',
830 help='check the kernel cmdline file against these preferences')
831 parser.add_argument('-m', '--mode', choices=report_modes,
832 help='choose the report mode')
833 args = parser.parse_args()
839 print('[+] Special report mode: {}'.format(mode))
841 config_checklist = []
845 sys.exit('[!] ERROR: --config and --print can\'t be used together')
848 print('[+] Kconfig file to check: {}'.format(args.config))
850 print('[+] Kernel cmdline file to check: {}'.format(args.cmdline))
852 arch, msg = detect_arch(args.config, supported_archs)
854 sys.exit('[!] ERROR: {}'.format(msg))
856 print('[+] Detected architecture: {}'.format(arch))
858 kernel_version, msg = detect_version(args.config)
859 if not kernel_version:
860 sys.exit('[!] ERROR: {}'.format(msg))
862 print('[+] Detected kernel version: {}.{}'.format(kernel_version[0], kernel_version[1]))
864 # add relevant kconfig checks to the checklist
865 add_kconfig_checks(config_checklist, arch)
867 # populate the checklist with the parsed kconfig data
868 parsed_kconfig_options = OrderedDict()
869 parse_kconfig_file(parsed_kconfig_options, args.config)
870 populate_with_data(config_checklist, parsed_kconfig_options, 'kconfig')
871 populate_with_data(config_checklist, kernel_version, 'version')
874 # add relevant cmdline checks to the checklist
875 add_cmdline_checks(config_checklist, arch)
877 # populate the checklist with the parsed kconfig data
878 parsed_cmdline_options = OrderedDict()
879 parse_cmdline_file(parsed_cmdline_options, args.cmdline)
880 populate_with_data(config_checklist, parsed_cmdline_options, 'cmdline')
882 # now everything is ready for performing the checks
883 perform_checks(config_checklist)
885 # finally print the results
886 if mode == 'verbose':
887 print_unknown_options(config_checklist, parsed_kconfig_options)
888 print_checklist(mode, config_checklist, True)
892 sys.exit('[!] ERROR: checking cmdline doesn\'t work without checking kconfig')
895 if mode in ('show_ok', 'show_fail'):
896 sys.exit('[!] ERROR: wrong mode "{}" for --print'.format(mode))
898 add_kconfig_checks(config_checklist, arch)
899 add_cmdline_checks(config_checklist, arch)
901 print('[+] Printing kernel security hardening preferences for {}...'.format(arch))
902 print_checklist(mode, config_checklist, False)
908 if __name__ == '__main__':