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) or isinstance(opts[0], CmdlineCheck)), \
193 'invalid {} check: {}'.format(self.__class__.__name__, opts)
198 return self.opts[0].name
206 return self.opts[0].expected
210 return self.opts[0].decision
214 return self.opts[0].reason
216 def table_print(self, mode, with_results):
217 if mode == 'verbose':
218 print(' {:87}'.format('<<< ' + self.__class__.__name__ + ' >>>'), end='')
220 print('| {}'.format(self.result), end='')
223 o.table_print(mode, with_results)
226 o.table_print(mode, False)
228 print('| {}'.format(self.result), end='')
230 def json_dump(self, with_results):
231 dump = self.opts[0].json_dump(False)
233 dump.append(self.result)
237 class OR(ComplexOptCheck):
238 # self.opts[0] is the option that this OR-check is about.
240 # OR(<X_is_hardened>, <X_is_disabled>)
241 # OR(<X_is_hardened>, <old_X_is_hardened>)
243 for i, opt in enumerate(self.opts):
245 if opt.result.startswith('OK'):
246 self.result = opt.result
247 # Add more info for additional checks:
249 if opt.result == 'OK':
250 self.result = 'OK: {} "{}"'.format(opt.name, opt.expected)
251 elif opt.result == 'OK: not found':
252 self.result = 'OK: {} not found'.format(opt.name)
253 elif opt.result == 'OK: is present':
254 self.result = 'OK: {} is present'.format(opt.name)
256 # VersionCheck provides enough info
257 assert(opt.result.startswith('OK: version')), \
258 'unexpected OK description "{}"'.format(opt.result)
260 self.result = self.opts[0].result
263 class AND(ComplexOptCheck):
264 # self.opts[0] is the option that this AND-check is about.
266 # AND(<suboption>, <main_option>)
267 # Suboption is not checked if checking of the main_option is failed.
268 # AND(<X_is_disabled>, <old_X_is_disabled>)
270 for i, opt in reversed(list(enumerate(self.opts))):
273 self.result = opt.result
275 if not opt.result.startswith('OK'):
276 # This FAIL is caused by additional checks,
277 # and not by the main option that this AND-check is about.
278 # Describe the reason of the FAIL.
279 if opt.result.startswith('FAIL: \"') or opt.result == 'FAIL: not found':
280 self.result = 'FAIL: {} not "{}"'.format(opt.name, opt.expected)
281 elif opt.result == 'FAIL: not present':
282 self.result = 'FAIL: {} not present'.format(opt.name)
284 # VersionCheck provides enough info
285 self.result = opt.result
286 assert(opt.result.startswith('FAIL: version')), \
287 'unexpected FAIL description "{}"'.format(opt.result)
291 def detect_arch(fname, archs):
292 with open(fname, 'r') as f:
293 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
295 for line in f.readlines():
296 if arch_pattern.match(line):
297 option, _ = line[7:].split('=', 1)
302 return None, 'more than one supported architecture is detected'
304 return None, 'failed to detect architecture'
308 def detect_version(fname):
309 with open(fname, 'r') as f:
310 ver_pattern = re.compile("# Linux/.* Kernel Configuration")
311 for line in f.readlines():
312 if ver_pattern.match(line):
316 ver_numbers = ver_str.split('.')
317 if len(ver_numbers) < 3 or not ver_numbers[0].isdigit() or not ver_numbers[1].isdigit():
318 msg = 'failed to parse the version "' + ver_str + '"'
320 return (int(ver_numbers[0]), int(ver_numbers[1])), None
321 return None, 'no kernel version detected'
324 def add_kconfig_checks(l, arch):
325 # Calling the KconfigCheck class constructor:
326 # KconfigCheck(reason, decision, name, expected)
328 modules_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'MODULES', 'is not set')
329 devmem_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'DEVMEM', 'is not set') # refers to LOCKDOWN
330 bpf_syscall_not_set = KconfigCheck('cut_attack_surface', 'lockdown', 'BPF_SYSCALL', 'is not set') # refers to LOCKDOWN
331 efi_not_set = KconfigCheck('cut_attack_surface', 'my', 'EFI', 'is not set')
333 # 'self_protection', 'defconfig'
334 l += [KconfigCheck('self_protection', 'defconfig', 'BUG', 'y')]
335 l += [KconfigCheck('self_protection', 'defconfig', 'SLUB_DEBUG', 'y')]
336 l += [KconfigCheck('self_protection', 'defconfig', 'GCC_PLUGINS', 'y')]
337 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR', 'y'),
338 KconfigCheck('self_protection', 'defconfig', 'CC_STACKPROTECTOR', 'y'))]
339 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR_STRONG', 'y'),
340 KconfigCheck('self_protection', 'defconfig', 'CC_STACKPROTECTOR_STRONG', 'y'))]
341 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STRICT_KERNEL_RWX', 'y'),
342 KconfigCheck('self_protection', 'defconfig', 'DEBUG_RODATA', 'y'))] # before v4.11
343 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STRICT_MODULE_RWX', 'y'),
344 KconfigCheck('self_protection', 'defconfig', 'DEBUG_SET_MODULE_RONX', 'y'),
345 modules_not_set)] # DEBUG_SET_MODULE_RONX was before v4.11
346 l += [OR(KconfigCheck('self_protection', 'defconfig', 'REFCOUNT_FULL', 'y'),
347 VersionCheck((5, 5)))] # REFCOUNT_FULL is enabled by default since v5.5
348 l += [KconfigCheck('self_protection', 'defconfig', 'THREAD_INFO_IN_TASK', 'y')]
349 iommu_support_is_set = KconfigCheck('self_protection', 'defconfig', 'IOMMU_SUPPORT', 'y')
350 l += [iommu_support_is_set] # is needed for mitigating DMA attacks
351 if arch in ('X86_64', 'ARM64', 'X86_32'):
352 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_BASE', 'y')]
353 if arch in ('X86_64', 'ARM64'):
354 l += [KconfigCheck('self_protection', 'defconfig', 'VMAP_STACK', 'y')]
355 if arch in ('X86_64', 'X86_32'):
356 l += [KconfigCheck('self_protection', 'defconfig', 'MICROCODE', 'y')] # is needed for mitigating CPU bugs
357 l += [KconfigCheck('self_protection', 'defconfig', 'RETPOLINE', 'y')]
358 l += [KconfigCheck('self_protection', 'defconfig', 'X86_SMAP', 'y')]
359 l += [KconfigCheck('self_protection', 'defconfig', 'SYN_COOKIES', 'y')] # another reason?
360 l += [OR(KconfigCheck('self_protection', 'defconfig', 'X86_UMIP', 'y'),
361 KconfigCheck('self_protection', 'defconfig', 'X86_INTEL_UMIP', 'y'))]
362 if arch in ('ARM64', 'ARM'):
363 l += [KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR_PER_TASK', 'y')]
365 l += [KconfigCheck('self_protection', 'defconfig', 'PAGE_TABLE_ISOLATION', 'y')]
366 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_MEMORY', 'y')]
367 l += [AND(KconfigCheck('self_protection', 'defconfig', 'INTEL_IOMMU', 'y'),
368 iommu_support_is_set)]
369 l += [AND(KconfigCheck('self_protection', 'defconfig', 'AMD_IOMMU', 'y'),
370 iommu_support_is_set)]
372 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_PAN', 'y')]
373 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_EPAN', 'y')]
374 l += [KconfigCheck('self_protection', 'defconfig', 'UNMAP_KERNEL_AT_EL0', 'y')]
375 l += [OR(KconfigCheck('self_protection', 'defconfig', 'HARDEN_EL2_VECTORS', 'y'),
376 AND(KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_BASE', 'y'),
377 VersionCheck((5, 9))))] # HARDEN_EL2_VECTORS was included in RANDOMIZE_BASE in v5.9
378 l += [KconfigCheck('self_protection', 'defconfig', 'RODATA_FULL_DEFAULT_ENABLED', 'y')]
379 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_PTR_AUTH_KERNEL', 'y')]
380 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_BTI_KERNEL', 'y')]
381 l += [OR(KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_PREDICTOR', 'y'),
382 VersionCheck((5, 10)))] # HARDEN_BRANCH_PREDICTOR is enabled by default since v5.10
383 l += [KconfigCheck('self_protection', 'defconfig', 'MITIGATE_SPECTRE_BRANCH_HISTORY', 'y')]
384 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_MTE', 'y')]
385 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_MODULE_REGION_FULL', 'y')]
387 l += [KconfigCheck('self_protection', 'defconfig', 'CPU_SW_DOMAIN_PAN', 'y')]
388 l += [KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_PREDICTOR', 'y')]
389 l += [KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_HISTORY', 'y')]
391 # 'self_protection', 'kspp'
392 l += [KconfigCheck('self_protection', 'kspp', 'SECURITY_DMESG_RESTRICT', 'y')]
393 l += [KconfigCheck('self_protection', 'kspp', 'BUG_ON_DATA_CORRUPTION', 'y')]
394 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_WX', 'y')]
395 l += [KconfigCheck('self_protection', 'kspp', 'SCHED_STACK_END_CHECK', 'y')]
396 l += [KconfigCheck('self_protection', 'kspp', 'SLAB_FREELIST_HARDENED', 'y')]
397 l += [KconfigCheck('self_protection', 'kspp', 'SLAB_FREELIST_RANDOM', 'y')]
398 l += [KconfigCheck('self_protection', 'kspp', 'SHUFFLE_PAGE_ALLOCATOR', 'y')]
399 l += [KconfigCheck('self_protection', 'kspp', 'FORTIFY_SOURCE', 'y')]
400 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_LIST', 'y')]
401 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_SG', 'y')]
402 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_CREDENTIALS', 'y')]
403 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_NOTIFIERS', 'y')]
404 l += [KconfigCheck('self_protection', 'kspp', 'INIT_ON_ALLOC_DEFAULT_ON', 'y')]
405 l += [KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_LATENT_ENTROPY', 'y')]
406 l += [KconfigCheck('self_protection', 'kspp', 'KFENCE', 'y')]
407 l += [KconfigCheck('self_protection', 'kspp', 'WERROR', 'y')]
408 l += [KconfigCheck('self_protection', 'kspp', 'IOMMU_DEFAULT_DMA_STRICT', 'y')]
409 l += [KconfigCheck('self_protection', 'kspp', 'ZERO_CALL_USED_REGS', 'y')]
410 randstruct_is_set = KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_RANDSTRUCT', 'y')
411 l += [randstruct_is_set]
412 hardened_usercopy_is_set = KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY', 'y')
413 l += [hardened_usercopy_is_set]
414 l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_FALLBACK', 'is not set'),
415 hardened_usercopy_is_set)]
416 l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_PAGESPAN', 'is not set'),
417 hardened_usercopy_is_set)]
418 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG', 'y'),
420 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_ALL', 'y'),
422 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_SHA512', 'y'),
424 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_FORCE', 'y'),
425 modules_not_set)] # refers to LOCKDOWN
426 l += [OR(KconfigCheck('self_protection', 'kspp', 'INIT_STACK_ALL_ZERO', 'y'),
427 KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_STRUCTLEAK_BYREF_ALL', 'y'))]
428 l += [OR(KconfigCheck('self_protection', 'kspp', 'INIT_ON_FREE_DEFAULT_ON', 'y'),
429 KconfigCheck('self_protection', 'kspp', 'PAGE_POISONING_ZERO', 'y'))]
430 # CONFIG_INIT_ON_FREE_DEFAULT_ON was added in v5.3.
431 # CONFIG_PAGE_POISONING_ZERO was removed in v5.11.
432 # Starting from v5.11 CONFIG_PAGE_POISONING unconditionally checks
433 # the 0xAA poison pattern on allocation.
434 # That brings higher performance penalty.
435 if arch in ('X86_64', 'ARM64', 'X86_32'):
436 stackleak_is_set = KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_STACKLEAK', 'y')
437 l += [stackleak_is_set]
438 l += [OR(KconfigCheck('self_protection', 'kspp', 'RANDOMIZE_KSTACK_OFFSET_DEFAULT', 'y'),
439 CmdlineCheck('self_protection', 'kspp', 'randomize_kstack_offset', '1'))]
440 if arch in ('X86_64', 'X86_32'):
441 l += [KconfigCheck('self_protection', 'kspp', 'SCHED_CORE', 'y')]
442 l += [KconfigCheck('self_protection', 'kspp', 'DEFAULT_MMAP_MIN_ADDR', '65536')]
443 if arch in ('ARM64', 'ARM'):
444 l += [KconfigCheck('self_protection', 'kspp', 'DEFAULT_MMAP_MIN_ADDR', '32768')]
445 l += [KconfigCheck('self_protection', 'kspp', 'SYN_COOKIES', 'y')] # another reason?
447 l += [KconfigCheck('self_protection', 'kspp', 'ARM64_SW_TTBR0_PAN', 'y')]
449 l += [KconfigCheck('self_protection', 'kspp', 'PAGE_TABLE_ISOLATION', 'y')]
450 l += [KconfigCheck('self_protection', 'kspp', 'HIGHMEM64G', 'y')]
451 l += [KconfigCheck('self_protection', 'kspp', 'X86_PAE', 'y')]
453 # 'self_protection', 'maintainer'
454 ubsan_bounds_is_set = KconfigCheck('self_protection', 'maintainer', 'UBSAN_BOUNDS', 'y') # only array index bounds checking
455 l += [ubsan_bounds_is_set] # recommended by Kees Cook in /issues/53
456 if arch in ('X86_64', 'ARM64', 'X86_32'): # ARCH_HAS_UBSAN_SANITIZE_ALL is not enabled for ARM
457 l += [AND(KconfigCheck('self_protection', 'maintainer', 'UBSAN_SANITIZE_ALL', 'y'),
458 ubsan_bounds_is_set)] # recommended by Kees Cook in /issues/53
459 l += [AND(KconfigCheck('self_protection', 'maintainer', 'UBSAN_TRAP', 'y'),
460 ubsan_bounds_is_set)] # recommended by Kees Cook in /issues/53
462 # 'self_protection', 'clipos'
463 l += [KconfigCheck('self_protection', 'clipos', 'DEBUG_VIRTUAL', 'y')]
464 l += [KconfigCheck('self_protection', 'clipos', 'STATIC_USERMODEHELPER', 'y')] # needs userspace support
465 l += [OR(KconfigCheck('self_protection', 'clipos', 'EFI_DISABLE_PCI_DMA', 'y'),
467 l += [OR(KconfigCheck('self_protection', 'clipos', 'SLAB_MERGE_DEFAULT', 'is not set'),
468 CmdlineCheck('self_protection', 'kspp', 'slab_nomerge'))] # option presence check
469 l += [KconfigCheck('self_protection', 'clipos', 'RANDOM_TRUST_BOOTLOADER', 'is not set')]
470 l += [KconfigCheck('self_protection', 'clipos', 'RANDOM_TRUST_CPU', 'is not set')]
471 l += [AND(KconfigCheck('self_protection', 'clipos', 'GCC_PLUGIN_RANDSTRUCT_PERFORMANCE', 'is not set'),
473 if arch in ('X86_64', 'ARM64', 'X86_32'):
474 l += [AND(KconfigCheck('self_protection', 'clipos', 'STACKLEAK_METRICS', 'is not set'),
476 l += [AND(KconfigCheck('self_protection', 'clipos', 'STACKLEAK_RUNTIME_DISABLE', 'is not set'),
478 if arch in ('X86_64', 'X86_32'):
479 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU_DEFAULT_ON', 'y'),
480 iommu_support_is_set)]
482 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU_SVM', 'y'),
483 iommu_support_is_set)]
485 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU', 'y'),
486 iommu_support_is_set)]
488 # 'self_protection', 'my'
489 l += [OR(KconfigCheck('self_protection', 'my', 'RESET_ATTACK_MITIGATION', 'y'),
490 efi_not_set)] # needs userspace support (systemd)
492 l += [KconfigCheck('self_protection', 'my', 'SLS', 'y')] # vs CVE-2021-26341 in Straight-Line-Speculation
493 l += [AND(KconfigCheck('self_protection', 'my', 'AMD_IOMMU_V2', 'y'),
494 iommu_support_is_set)]
496 l += [KconfigCheck('self_protection', 'my', 'SHADOW_CALL_STACK', 'y')] # depends on clang, maybe it's alternative to STACKPROTECTOR_STRONG
497 l += [KconfigCheck('self_protection', 'my', 'KASAN_HW_TAGS', 'y')]
498 cfi_clang_is_set = KconfigCheck('self_protection', 'my', 'CFI_CLANG', 'y')
499 l += [cfi_clang_is_set]
500 l += [AND(KconfigCheck('self_protection', 'my', 'CFI_PERMISSIVE', 'is not set'),
504 if arch in ('X86_64', 'ARM64', 'X86_32'):
505 l += [KconfigCheck('security_policy', 'defconfig', 'SECURITY', 'y')] # and choose your favourite LSM
507 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY', 'y')] # and choose your favourite LSM
508 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY_YAMA', 'y')]
509 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY_SELINUX_DISABLE', 'is not set')]
510 l += [KconfigCheck('security_policy', 'clipos', 'SECURITY_LOCKDOWN_LSM', 'y')]
511 l += [KconfigCheck('security_policy', 'clipos', 'SECURITY_LOCKDOWN_LSM_EARLY', 'y')]
512 l += [KconfigCheck('security_policy', 'clipos', 'LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY', 'y')]
513 l += [KconfigCheck('security_policy', 'my', 'SECURITY_WRITABLE_HOOKS', 'is not set')] # refers to SECURITY_SELINUX_DISABLE
514 l += [KconfigCheck('security_policy', 'my', 'SECURITY_SAFESETID', 'y')]
515 loadpin_is_set = KconfigCheck('security_policy', 'my', 'SECURITY_LOADPIN', 'y')
516 l += [loadpin_is_set] # needs userspace support
517 l += [AND(KconfigCheck('security_policy', 'my', 'SECURITY_LOADPIN_ENFORCE', 'y'),
520 # 'cut_attack_surface', 'defconfig'
521 l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'BPF_UNPRIV_DEFAULT_OFF', 'y'),
522 bpf_syscall_not_set)] # see unprivileged_bpf_disabled
523 l += [KconfigCheck('cut_attack_surface', 'defconfig', 'SECCOMP', 'y')]
524 l += [KconfigCheck('cut_attack_surface', 'defconfig', 'SECCOMP_FILTER', 'y')]
525 if arch in ('X86_64', 'ARM64', 'X86_32'):
526 l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'STRICT_DEVMEM', 'y'),
527 devmem_not_set)] # refers to LOCKDOWN
529 # 'cut_attack_surface', 'kspp'
530 l += [KconfigCheck('cut_attack_surface', 'kspp', 'ACPI_CUSTOM_METHOD', 'is not set')] # refers to LOCKDOWN
531 l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_BRK', 'is not set')]
532 l += [KconfigCheck('cut_attack_surface', 'kspp', 'DEVKMEM', 'is not set')] # refers to LOCKDOWN
533 l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_VDSO', 'is not set')]
534 l += [KconfigCheck('cut_attack_surface', 'kspp', 'BINFMT_MISC', 'is not set')]
535 l += [KconfigCheck('cut_attack_surface', 'kspp', 'INET_DIAG', 'is not set')]
536 l += [KconfigCheck('cut_attack_surface', 'kspp', 'KEXEC', 'is not set')] # refers to LOCKDOWN
537 l += [KconfigCheck('cut_attack_surface', 'kspp', 'PROC_KCORE', 'is not set')] # refers to LOCKDOWN
538 l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_PTYS', 'is not set')]
539 l += [KconfigCheck('cut_attack_surface', 'kspp', 'HIBERNATION', 'is not set')] # refers to LOCKDOWN
540 l += [KconfigCheck('cut_attack_surface', 'kspp', 'IA32_EMULATION', 'is not set')]
541 l += [KconfigCheck('cut_attack_surface', 'kspp', 'X86_X32', 'is not set')]
542 l += [KconfigCheck('cut_attack_surface', 'kspp', 'MODIFY_LDT_SYSCALL', 'is not set')]
543 l += [KconfigCheck('cut_attack_surface', 'kspp', 'OABI_COMPAT', 'is not set')]
544 l += [KconfigCheck('cut_attack_surface', 'kspp', 'X86_MSR', 'is not set')] # refers to LOCKDOWN
545 l += [modules_not_set]
546 l += [devmem_not_set]
547 l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'IO_STRICT_DEVMEM', 'y'),
548 devmem_not_set)] # refers to LOCKDOWN
550 l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'STRICT_DEVMEM', 'y'),
551 devmem_not_set)] # refers to LOCKDOWN
553 l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_VSYSCALL_NONE', 'y')] # 'vsyscall=none'
555 # 'cut_attack_surface', 'grsec'
556 l += [KconfigCheck('cut_attack_surface', 'grsec', 'ZSMALLOC_STAT', 'is not set')]
557 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PAGE_OWNER', 'is not set')]
558 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEBUG_KMEMLEAK', 'is not set')]
559 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BINFMT_AOUT', 'is not set')]
560 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KPROBE_EVENTS', 'is not set')]
561 l += [KconfigCheck('cut_attack_surface', 'grsec', 'UPROBE_EVENTS', 'is not set')]
562 l += [KconfigCheck('cut_attack_surface', 'grsec', 'GENERIC_TRACER', 'is not set')] # refers to LOCKDOWN
563 l += [KconfigCheck('cut_attack_surface', 'grsec', 'FUNCTION_TRACER', 'is not set')]
564 l += [KconfigCheck('cut_attack_surface', 'grsec', 'STACK_TRACER', 'is not set')]
565 l += [KconfigCheck('cut_attack_surface', 'grsec', 'HIST_TRIGGERS', 'is not set')]
566 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BLK_DEV_IO_TRACE', 'is not set')]
567 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROC_VMCORE', 'is not set')]
568 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROC_PAGE_MONITOR', 'is not set')]
569 l += [KconfigCheck('cut_attack_surface', 'grsec', 'USELIB', 'is not set')]
570 l += [KconfigCheck('cut_attack_surface', 'grsec', 'CHECKPOINT_RESTORE', 'is not set')]
571 l += [KconfigCheck('cut_attack_surface', 'grsec', 'USERFAULTFD', 'is not set')]
572 l += [KconfigCheck('cut_attack_surface', 'grsec', 'HWPOISON_INJECT', 'is not set')]
573 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MEM_SOFT_DIRTY', 'is not set')]
574 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEVPORT', 'is not set')] # refers to LOCKDOWN
575 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEBUG_FS', 'is not set')] # refers to LOCKDOWN
576 l += [KconfigCheck('cut_attack_surface', 'grsec', 'NOTIFIER_ERROR_INJECTION', 'is not set')]
577 l += [KconfigCheck('cut_attack_surface', 'grsec', 'FAIL_FUTEX', 'is not set')]
578 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PUNIT_ATOM_DEBUG', 'is not set')]
579 l += [KconfigCheck('cut_attack_surface', 'grsec', 'ACPI_CONFIGFS', 'is not set')]
580 l += [KconfigCheck('cut_attack_surface', 'grsec', 'EDAC_DEBUG', 'is not set')]
581 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DRM_I915_DEBUG', 'is not set')]
582 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BCACHE_CLOSURES_DEBUG', 'is not set')]
583 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DVB_C8SECTPFE', 'is not set')]
584 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MTD_SLRAM', 'is not set')]
585 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MTD_PHRAM', 'is not set')]
586 l += [KconfigCheck('cut_attack_surface', 'grsec', 'IO_URING', 'is not set')]
587 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KCMP', 'is not set')]
588 l += [KconfigCheck('cut_attack_surface', 'grsec', 'RSEQ', 'is not set')]
589 l += [KconfigCheck('cut_attack_surface', 'grsec', 'LATENCYTOP', 'is not set')]
590 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KCOV', 'is not set')]
591 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROVIDE_OHCI1394_DMA_INIT', 'is not set')]
592 l += [KconfigCheck('cut_attack_surface', 'grsec', 'SUNRPC_DEBUG', 'is not set')]
593 l += [AND(KconfigCheck('cut_attack_surface', 'grsec', 'PTDUMP_DEBUGFS', 'is not set'),
594 KconfigCheck('cut_attack_surface', 'grsec', 'X86_PTDUMP', 'is not set'))]
596 # 'cut_attack_surface', 'maintainer'
597 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'DRM_LEGACY', 'is not set')] # recommended by Daniel Vetter in /issues/38
598 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'FB', 'is not set')] # recommended by Daniel Vetter in /issues/38
599 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'VT', 'is not set')] # recommended by Daniel Vetter in /issues/38
600 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'BLK_DEV_FD', 'is not set')] # recommended by Denis Efremov in /pull/54
601 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'BLK_DEV_FD_RAWCMD', 'is not set')] # recommended by Denis Efremov in /pull/62
603 # 'cut_attack_surface', 'grapheneos'
604 l += [KconfigCheck('cut_attack_surface', 'grapheneos', 'AIO', 'is not set')]
606 # 'cut_attack_surface', 'clipos'
607 l += [KconfigCheck('cut_attack_surface', 'clipos', 'STAGING', 'is not set')]
608 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KSM', 'is not set')] # to prevent FLUSH+RELOAD attack
609 # l += [KconfigCheck('cut_attack_surface', 'clipos', 'IKCONFIG', 'is not set')] # no, IKCONFIG is needed for this check :)
610 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KALLSYMS', 'is not set')]
611 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_VSYSCALL_EMULATION', 'is not set')]
612 l += [KconfigCheck('cut_attack_surface', 'clipos', 'MAGIC_SYSRQ', 'is not set')]
613 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KEXEC_FILE', 'is not set')] # refers to LOCKDOWN (permissive)
614 l += [KconfigCheck('cut_attack_surface', 'clipos', 'USER_NS', 'is not set')] # user.max_user_namespaces=0
615 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_CPUID', 'is not set')]
616 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_IOPL_IOPERM', 'is not set')] # refers to LOCKDOWN
617 l += [KconfigCheck('cut_attack_surface', 'clipos', 'ACPI_TABLE_UPGRADE', 'is not set')] # refers to LOCKDOWN
618 l += [KconfigCheck('cut_attack_surface', 'clipos', 'EFI_CUSTOM_SSDT_OVERLAYS', 'is not set')]
619 l += [AND(KconfigCheck('cut_attack_surface', 'clipos', 'LDISC_AUTOLOAD', 'is not set'),
620 KconfigCheck('cut_attack_surface', 'clipos', 'LDISC_AUTOLOAD'))] # option presence check
621 if arch in ('X86_64', 'X86_32'):
622 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_INTEL_TSX_MODE_OFF', 'y')] # tsx=off
624 # 'cut_attack_surface', 'lockdown'
625 l += [bpf_syscall_not_set] # refers to LOCKDOWN
626 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'EFI_TEST', 'is not set')] # refers to LOCKDOWN
627 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'MMIOTRACE_TEST', 'is not set')] # refers to LOCKDOWN
628 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'KPROBES', 'is not set')] # refers to LOCKDOWN
630 # 'cut_attack_surface', 'my'
631 l += [OR(KconfigCheck('cut_attack_surface', 'my', 'TRIM_UNUSED_KSYMS', 'y'),
633 l += [KconfigCheck('cut_attack_surface', 'my', 'MMIOTRACE', 'is not set')] # refers to LOCKDOWN (permissive)
634 l += [KconfigCheck('cut_attack_surface', 'my', 'LIVEPATCH', 'is not set')]
635 l += [KconfigCheck('cut_attack_surface', 'my', 'IP_DCCP', 'is not set')]
636 l += [KconfigCheck('cut_attack_surface', 'my', 'IP_SCTP', 'is not set')]
637 l += [KconfigCheck('cut_attack_surface', 'my', 'FTRACE', 'is not set')] # refers to LOCKDOWN
638 l += [KconfigCheck('cut_attack_surface', 'my', 'VIDEO_VIVID', 'is not set')]
639 l += [KconfigCheck('cut_attack_surface', 'my', 'INPUT_EVBUG', 'is not set')] # Can be used as a keylogger
640 l += [KconfigCheck('cut_attack_surface', 'my', 'KGDB', 'is not set')]
643 if arch in ('X86_64', 'ARM64', 'X86_32'):
644 l += [KconfigCheck('harden_userspace', 'defconfig', 'INTEGRITY', 'y')]
646 l += [KconfigCheck('harden_userspace', 'my', 'INTEGRITY', 'y')]
647 if arch in ('ARM', 'X86_32'):
648 l += [KconfigCheck('harden_userspace', 'defconfig', 'VMSPLIT_3G', 'y')]
649 if arch in ('X86_64', 'ARM64'):
650 l += [KconfigCheck('harden_userspace', 'clipos', 'ARCH_MMAP_RND_BITS', '32')]
651 if arch in ('X86_32', 'ARM'):
652 l += [KconfigCheck('harden_userspace', 'my', 'ARCH_MMAP_RND_BITS', '16')]
654 # l += [KconfigCheck('feature_test', 'my', 'LKDTM', 'm')] # only for debugging!
657 def add_cmdline_checks(l, arch):
658 # Calling the CmdlineCheck class constructor:
659 # CmdlineCheck(reason, decision, name, expected)
661 if arch in ('X86_64', 'X86_32'):
662 l += [CmdlineCheck('self_protection', 'kspp', 'pti', 'on')]
666 def print_unknown_options(checklist, parsed_options):
670 if o1.type != 'complex':
671 known_options.append(o1.name)
674 if o2.type != 'complex':
675 if hasattr(o2, 'name'):
676 known_options.append(o2.name)
679 assert(o3.type != 'complex'), \
680 'unexpected ComplexOptCheck inside {}'.format(o2.name)
681 if hasattr(o3, 'name'):
682 known_options.append(o3.name)
684 for option, value in parsed_options.items():
685 if option not in known_options:
686 print('[?] No check for option {} ({})'.format(option, value))
689 def print_checklist(mode, checklist, with_results):
693 output.append(o.json_dump(with_results))
694 print(json.dumps(output))
701 print('=' * sep_line_len)
702 print('{:^40}|{:^7}|{:^12}|{:^10}|{:^18}'.format('option name', 'type', 'desired val', 'decision', 'reason'), end='')
704 print('| {}'.format('check result'), end='')
706 print('=' * sep_line_len)
709 for opt in checklist:
711 if mode == 'show_ok':
712 if not opt.result.startswith('OK'):
714 if mode == 'show_fail':
715 if not opt.result.startswith('FAIL'):
717 opt.table_print(mode, with_results)
719 if mode == 'verbose':
720 print('-' * sep_line_len)
725 fail_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
727 ok_count = len(list(filter(lambda opt: opt.result.startswith('OK'), checklist)))
729 if mode == 'show_ok':
730 fail_suppressed = ' (suppressed in output)'
731 if mode == 'show_fail':
732 ok_suppressed = ' (suppressed in output)'
734 print('[+] Config check is finished: \'OK\' - {}{} / \'FAIL\' - {}{}'.format(ok_count, ok_suppressed, fail_count, fail_suppressed))
737 def populate_simple_opt_with_data(opt, data, data_type):
738 assert(opt.type != 'complex'), \
739 'unexpected ComplexOptCheck "{}"'.format(opt.name)
740 assert(opt.type in SIMPLE_OPTION_TYPES), \
741 'invalid opt type "{}"'.format(opt.type)
742 assert(data_type in SIMPLE_OPTION_TYPES), \
743 'invalid data type "{}"'.format(data_type)
745 if data_type != opt.type:
748 if data_type in ('kconfig', 'cmdline'):
749 opt.state = data.get(opt.name, None)
751 assert(data_type == 'version'), \
752 'unexpected data type "{}"'.format(data_type)
756 def populate_opt_with_data(opt, data, data_type):
757 if opt.type == 'complex':
759 if o.type == 'complex':
760 # Recursion for nested ComplexOptCheck objects
761 populate_opt_with_data(o, data, data_type)
763 populate_simple_opt_with_data(o, data, data_type)
765 assert(opt.type in ('kconfig', 'cmdline')), \
766 'bad type "{}" for a simple check'.format(opt.type)
767 populate_simple_opt_with_data(opt, data, data_type)
770 def populate_with_data(checklist, data, data_type):
771 for opt in checklist:
772 populate_opt_with_data(opt, data, data_type)
775 def perform_checks(checklist):
776 for opt in checklist:
780 def parse_kconfig_file(parsed_options, fname):
781 with open(fname, 'r') as f:
782 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
783 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
785 for line in f.readlines():
790 if opt_is_on.match(line):
791 option, value = line.split('=', 1)
792 elif opt_is_off.match(line):
793 option, value = line[2:].split(' ', 1)
794 if value != 'is not set':
795 sys.exit('[!] ERROR: bad disabled kconfig option "{}"'.format(line))
797 if option in parsed_options:
798 sys.exit('[!] ERROR: kconfig option "{}" exists multiple times'.format(line))
801 parsed_options[option] = value
804 def parse_cmdline_file(parsed_options, fname):
805 with open(fname, 'r') as f:
811 sys.exit('[!] ERROR: more than one line in "{}"'.format(fname))
815 name, value = opt.split('=', 1)
818 value = '' # '' is not None
819 parsed_options[name] = value
825 # - reporting about unknown kernel options in the kconfig
826 # - verbose printing of ComplexOptCheck items
827 # * json mode for printing the results in JSON format
828 report_modes = ['verbose', 'json', 'show_ok', 'show_fail']
829 supported_archs = ['X86_64', 'X86_32', 'ARM64', 'ARM']
830 parser = ArgumentParser(prog='kconfig-hardened-check',
831 description='A tool for checking the security hardening options of the Linux kernel')
832 parser.add_argument('--version', action='version', version='%(prog)s ' + __version__)
833 parser.add_argument('-p', '--print', choices=supported_archs,
834 help='print security hardening preferences for the selected architecture')
835 parser.add_argument('-c', '--config',
836 help='check the kernel kconfig file against these preferences')
837 parser.add_argument('-l', '--cmdline',
838 help='check the kernel cmdline file against these preferences')
839 parser.add_argument('-m', '--mode', choices=report_modes,
840 help='choose the report mode')
841 args = parser.parse_args()
847 print('[+] Special report mode: {}'.format(mode))
849 config_checklist = []
853 sys.exit('[!] ERROR: --config and --print can\'t be used together')
856 print('[+] Kconfig file to check: {}'.format(args.config))
858 print('[+] Kernel cmdline file to check: {}'.format(args.cmdline))
860 arch, msg = detect_arch(args.config, supported_archs)
862 sys.exit('[!] ERROR: {}'.format(msg))
864 print('[+] Detected architecture: {}'.format(arch))
866 kernel_version, msg = detect_version(args.config)
867 if not kernel_version:
868 sys.exit('[!] ERROR: {}'.format(msg))
870 print('[+] Detected kernel version: {}.{}'.format(kernel_version[0], kernel_version[1]))
872 # add relevant kconfig checks to the checklist
873 add_kconfig_checks(config_checklist, arch)
875 # populate the checklist with the parsed kconfig data
876 parsed_kconfig_options = OrderedDict()
877 parse_kconfig_file(parsed_kconfig_options, args.config)
878 populate_with_data(config_checklist, parsed_kconfig_options, 'kconfig')
879 populate_with_data(config_checklist, kernel_version, 'version')
882 # add relevant cmdline checks to the checklist
883 add_cmdline_checks(config_checklist, arch)
885 # populate the checklist with the parsed kconfig data
886 parsed_cmdline_options = OrderedDict()
887 parse_cmdline_file(parsed_cmdline_options, args.cmdline)
888 populate_with_data(config_checklist, parsed_cmdline_options, 'cmdline')
890 # now everything is ready for performing the checks
891 perform_checks(config_checklist)
893 # finally print the results
894 if mode == 'verbose':
895 print_unknown_options(config_checklist, parsed_kconfig_options)
896 print_checklist(mode, config_checklist, True)
900 sys.exit('[!] ERROR: checking cmdline doesn\'t work without checking kconfig')
903 if mode in ('show_ok', 'show_fail'):
904 sys.exit('[!] ERROR: wrong mode "{}" for --print'.format(mode))
906 add_kconfig_checks(config_checklist, arch)
907 add_cmdline_checks(config_checklist, arch)
909 print('[+] Printing kernel security hardening preferences for {}...'.format(arch))
910 print_checklist(mode, config_checklist, False)
916 if __name__ == '__main__':