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:
15 # page_alloc.shuffle=1
16 # iommu=force (does it help against DMA attacks?)
17 # slub_debug=FZ (slow)
18 # init_on_alloc=1 (since v5.3)
19 # init_on_free=1 (since v5.3, otherwise slub_debug=P and page_poison=1)
21 # debugfs=no-mount (or off if possible)
22 # randomize_kstack_offset=1
24 # Mitigations of CPU vulnerabilities:
26 # mitigations=auto,nosmt (nosmt is slow)
30 # spec_store_bypass_disable=on
32 # l1d_flush=on (a part of the l1tf option)
44 # Hardware tag-based KASAN with arm64 Memory Tagging Extension (MTE):
46 # kasan.stacktrace=off
49 # N.B. Hardening sysctls:
50 # kernel.kptr_restrict=2 (or 1?)
51 # kernel.dmesg_restrict=1 (also see the kconfig option)
52 # kernel.perf_event_paranoid=3
53 # kernel.kexec_load_disabled=1
54 # kernel.yama.ptrace_scope=3
55 # user.max_user_namespaces=0
56 # what about bpf_jit_enable?
57 # kernel.unprivileged_bpf_disabled=1
58 # net.core.bpf_jit_harden=2
60 # vm.unprivileged_userfaultfd=0
61 # (at first, it disabled unprivileged userfaultfd,
62 # and since v5.11 it enables unprivileged userfaultfd for user-mode only)
64 # dev.tty.ldisc_autoload=0
65 # fs.protected_symlinks=1
66 # fs.protected_hardlinks=1
67 # fs.protected_fifos=2
68 # fs.protected_regular=2
70 # kernel.modules_disabled=1
73 # pylint: disable=missing-module-docstring,missing-class-docstring,missing-function-docstring
74 # pylint: disable=line-too-long,invalid-name,too-many-branches,too-many-statements
78 from argparse import ArgumentParser
79 from collections import OrderedDict
82 from .__about__ import __version__
84 TYPES_OF_CHECKS = ('kconfig', 'version')
87 def __init__(self, reason, decision, name, expected):
89 self.expected = expected
90 self.decision = decision
96 if self.expected == self.state:
98 elif self.state is None:
99 if self.expected == 'is not set':
100 self.result = 'OK: not found'
102 self.result = 'FAIL: not found'
104 self.result = 'FAIL: "' + self.state + '"'
106 def table_print(self, _mode, with_results):
107 print('{:<40}|{:^7}|{:^12}|{:^10}|{:^18}'.format(self.name, self.type, self.expected, self.decision, self.reason), end='')
109 print('| {}'.format(self.result), end='')
112 class KconfigCheck(OptCheck):
113 def __init__(self, *args, **kwargs):
114 super().__init__(*args, **kwargs)
115 self.name = 'CONFIG_' + self.name
121 def json_dump(self, with_results):
122 dump = [self.name, self.type, self.expected, self.decision, self.reason]
124 dump.append(self.result)
129 def __init__(self, ver_expected):
130 self.ver_expected = ver_expected
139 if self.ver[0] > self.ver_expected[0]:
140 self.result = 'OK: version >= ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
142 if self.ver[0] < self.ver_expected[0]:
143 self.result = 'FAIL: version < ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
145 if self.ver[1] >= self.ver_expected[1]:
146 self.result = 'OK: version >= ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
148 self.result = 'FAIL: version < ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
150 def table_print(self, _mode, with_results):
151 ver_req = 'kernel version >= ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
152 print('{:<91}'.format(ver_req), end='')
154 print('| {}'.format(self.result), end='')
158 def __init__(self, name, type):
160 if self.type == 'kconfig':
161 self.name = 'CONFIG_' + name
163 sys.exit('[!] ERROR: unsupported type "{}" for {}'.format(type, self.__class__.__name__))
168 if self.state is None:
169 self.result = 'FAIL: not present'
171 self.result = 'OK: is present'
173 def table_print(self, _mode, with_results):
174 print('{:<91}'.format(self.name + ' is present'), end='')
176 print('| {}'.format(self.result), end='')
179 class ComplexOptCheck:
180 def __init__(self, *opts):
183 sys.exit('[!] ERROR: empty {} check'.format(self.__class__.__name__))
184 if len(self.opts) == 1:
185 sys.exit('[!] ERROR: useless {} check'.format(self.__class__.__name__))
186 if not isinstance(opts[0], KconfigCheck):
187 sys.exit('[!] ERROR: invalid {} check: {}'.format(self.__class__.__name__, opts))
192 return self.opts[0].name
200 return self.opts[0].expected
204 return self.opts[0].decision
208 return self.opts[0].reason
210 def table_print(self, mode, with_results):
211 if mode == 'verbose':
212 print(' {:87}'.format('<<< ' + self.__class__.__name__ + ' >>>'), end='')
214 print('| {}'.format(self.result), end='')
217 o.table_print(mode, with_results)
220 o.table_print(mode, False)
222 print('| {}'.format(self.result), end='')
224 def json_dump(self, with_results):
225 dump = self.opts[0].json_dump(False)
227 dump.append(self.result)
231 class OR(ComplexOptCheck):
232 # self.opts[0] is the option that this OR-check is about.
234 # OR(<X_is_hardened>, <X_is_disabled>)
235 # OR(<X_is_hardened>, <old_X_is_hardened>)
238 sys.exit('[!] ERROR: invalid OR check')
239 for i, opt in enumerate(self.opts):
241 if opt.result.startswith('OK'):
242 if opt.result == 'OK' and i != 0:
243 # Simple OK is not enough for additional checks, add more info:
244 self.result = 'OK: {} "{}"'.format(opt.name, opt.expected)
246 self.result = opt.result
248 self.result = self.opts[0].result
251 class AND(ComplexOptCheck):
252 # self.opts[0] is the option that this AND-check is about.
254 # AND(<suboption>, <main_option>)
255 # Suboption is not checked if checking of the main_option is failed.
256 # AND(<X_is_disabled>, <old_X_is_disabled>)
258 for i, opt in reversed(list(enumerate(self.opts))):
261 self.result = opt.result
263 if not opt.result.startswith('OK'):
264 # This FAIL is caused by additional checks,
265 # and not by the main option that this AND-check is about.
266 # Describe the reason of the FAIL.
267 if opt.result.startswith('FAIL: \"') or opt.result == 'FAIL: not found':
268 self.result = 'FAIL: {} not "{}"'.format(opt.name, opt.expected)
269 elif opt.result == 'FAIL: not present':
270 self.result = 'FAIL: {} not present'.format(opt.name)
272 # This FAIL message is self-explaining.
273 self.result = opt.result
275 sys.exit('[!] ERROR: invalid AND check')
278 def detect_arch(fname, archs):
279 with open(fname, 'r') as f:
280 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
282 for line in f.readlines():
283 if arch_pattern.match(line):
284 option, _ = line[7:].split('=', 1)
289 return None, 'more than one supported architecture is detected'
291 return None, 'failed to detect architecture'
295 def detect_version(fname):
296 with open(fname, 'r') as f:
297 ver_pattern = re.compile("# Linux/.* Kernel Configuration")
298 for line in f.readlines():
299 if ver_pattern.match(line):
303 ver_numbers = ver_str.split('.')
304 if len(ver_numbers) < 3 or not ver_numbers[0].isdigit() or not ver_numbers[1].isdigit():
305 msg = 'failed to parse the version "' + ver_str + '"'
307 return (int(ver_numbers[0]), int(ver_numbers[1])), None
308 return None, 'no kernel version detected'
311 def add_kconfig_checks(l, arch):
312 # Calling the KconfigCheck class constructor:
313 # KconfigCheck(reason, decision, name, expected)
315 modules_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'MODULES', 'is not set')
316 devmem_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'DEVMEM', 'is not set') # refers to LOCKDOWN
317 bpf_syscall_not_set = KconfigCheck('cut_attack_surface', 'lockdown', 'BPF_SYSCALL', 'is not set') # refers to LOCKDOWN
318 efi_not_set = KconfigCheck('cut_attack_surface', 'my', 'EFI', 'is not set')
320 # 'self_protection', 'defconfig'
321 l += [KconfigCheck('self_protection', 'defconfig', 'BUG', 'y')]
322 l += [KconfigCheck('self_protection', 'defconfig', 'SLUB_DEBUG', 'y')]
323 l += [KconfigCheck('self_protection', 'defconfig', 'GCC_PLUGINS', 'y')]
324 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR_STRONG', 'y'),
325 KconfigCheck('self_protection', 'defconfig', 'CC_STACKPROTECTOR_STRONG', 'y'))]
326 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STRICT_KERNEL_RWX', 'y'),
327 KconfigCheck('self_protection', 'defconfig', 'DEBUG_RODATA', 'y'))] # before v4.11
328 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STRICT_MODULE_RWX', 'y'),
329 KconfigCheck('self_protection', 'defconfig', 'DEBUG_SET_MODULE_RONX', 'y'),
330 modules_not_set)] # DEBUG_SET_MODULE_RONX was before v4.11
331 l += [OR(KconfigCheck('self_protection', 'defconfig', 'REFCOUNT_FULL', 'y'),
332 VersionCheck((5, 5)))] # REFCOUNT_FULL is enabled by default since v5.5
333 l += [KconfigCheck('self_protection', 'defconfig', 'THREAD_INFO_IN_TASK', 'y')]
334 iommu_support_is_set = KconfigCheck('self_protection', 'defconfig', 'IOMMU_SUPPORT', 'y')
335 l += [iommu_support_is_set] # is needed for mitigating DMA attacks
336 if arch in ('X86_64', 'ARM64', 'X86_32'):
337 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_BASE', 'y')]
338 if arch in ('X86_64', 'ARM64'):
339 l += [KconfigCheck('self_protection', 'defconfig', 'VMAP_STACK', 'y')]
340 if arch in ('X86_64', 'X86_32'):
341 l += [KconfigCheck('self_protection', 'defconfig', 'MICROCODE', 'y')] # is needed for mitigating CPU bugs
342 l += [KconfigCheck('self_protection', 'defconfig', 'RETPOLINE', 'y')]
343 l += [KconfigCheck('self_protection', 'defconfig', 'X86_SMAP', 'y')]
344 l += [KconfigCheck('self_protection', 'defconfig', 'SYN_COOKIES', 'y')] # another reason?
345 l += [OR(KconfigCheck('self_protection', 'defconfig', 'X86_UMIP', 'y'),
346 KconfigCheck('self_protection', 'defconfig', 'X86_INTEL_UMIP', 'y'))]
347 if arch in ('ARM64', 'ARM'):
348 l += [KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR_PER_TASK', 'y')]
350 l += [KconfigCheck('self_protection', 'defconfig', 'PAGE_TABLE_ISOLATION', 'y')]
351 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_MEMORY', 'y')]
352 l += [AND(KconfigCheck('self_protection', 'defconfig', 'INTEL_IOMMU', 'y'),
353 iommu_support_is_set)]
354 l += [AND(KconfigCheck('self_protection', 'defconfig', 'AMD_IOMMU', 'y'),
355 iommu_support_is_set)]
357 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_PAN', 'y')]
358 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_EPAN', 'y')]
359 l += [KconfigCheck('self_protection', 'defconfig', 'UNMAP_KERNEL_AT_EL0', 'y')]
360 l += [OR(KconfigCheck('self_protection', 'defconfig', 'HARDEN_EL2_VECTORS', 'y'),
361 AND(KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_BASE', 'y'),
362 VersionCheck((5, 9))))] # HARDEN_EL2_VECTORS was included in RANDOMIZE_BASE in v5.9
363 l += [KconfigCheck('self_protection', 'defconfig', 'RODATA_FULL_DEFAULT_ENABLED', 'y')]
364 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_PTR_AUTH_KERNEL', 'y')]
365 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_BTI_KERNEL', 'y')]
366 l += [OR(KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_PREDICTOR', 'y'),
367 VersionCheck((5, 10)))] # HARDEN_BRANCH_PREDICTOR is enabled by default since v5.10
368 l += [KconfigCheck('self_protection', 'defconfig', 'MITIGATE_SPECTRE_BRANCH_HISTORY', 'y')]
369 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_MTE', 'y')]
371 l += [KconfigCheck('self_protection', 'defconfig', 'CPU_SW_DOMAIN_PAN', 'y')]
372 l += [KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_PREDICTOR', 'y')]
373 l += [KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_HISTORY', 'y')]
375 # 'self_protection', 'kspp'
376 l += [KconfigCheck('self_protection', 'kspp', 'SECURITY_DMESG_RESTRICT', 'y')]
377 l += [KconfigCheck('self_protection', 'kspp', 'BUG_ON_DATA_CORRUPTION', 'y')]
378 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_WX', 'y')]
379 l += [KconfigCheck('self_protection', 'kspp', 'SCHED_STACK_END_CHECK', 'y')]
380 l += [KconfigCheck('self_protection', 'kspp', 'SLAB_FREELIST_HARDENED', 'y')]
381 l += [KconfigCheck('self_protection', 'kspp', 'SLAB_FREELIST_RANDOM', 'y')]
382 l += [KconfigCheck('self_protection', 'kspp', 'SHUFFLE_PAGE_ALLOCATOR', 'y')]
383 l += [KconfigCheck('self_protection', 'kspp', 'FORTIFY_SOURCE', 'y')]
384 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_LIST', 'y')]
385 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_SG', 'y')]
386 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_CREDENTIALS', 'y')]
387 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_NOTIFIERS', 'y')]
388 l += [KconfigCheck('self_protection', 'kspp', 'INIT_ON_ALLOC_DEFAULT_ON', 'y')]
389 l += [KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_LATENT_ENTROPY', 'y')]
390 l += [KconfigCheck('self_protection', 'kspp', 'KFENCE', 'y')]
391 l += [KconfigCheck('self_protection', 'kspp', 'WERROR', 'y')]
392 randstruct_is_set = KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_RANDSTRUCT', 'y')
393 l += [randstruct_is_set]
394 hardened_usercopy_is_set = KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY', 'y')
395 l += [hardened_usercopy_is_set]
396 l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_FALLBACK', 'is not set'),
397 hardened_usercopy_is_set)]
398 l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_PAGESPAN', 'is not set'),
399 hardened_usercopy_is_set)]
400 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG', 'y'),
402 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_ALL', 'y'),
404 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_SHA512', 'y'),
406 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_FORCE', 'y'),
407 modules_not_set)] # refers to LOCKDOWN
408 l += [OR(KconfigCheck('self_protection', 'kspp', 'INIT_STACK_ALL_ZERO', 'y'),
409 KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_STRUCTLEAK_BYREF_ALL', 'y'))]
410 l += [OR(KconfigCheck('self_protection', 'kspp', 'INIT_ON_FREE_DEFAULT_ON', 'y'),
411 KconfigCheck('self_protection', 'kspp', 'PAGE_POISONING_ZERO', 'y'))]
412 # CONFIG_INIT_ON_FREE_DEFAULT_ON was added in v5.3.
413 # CONFIG_PAGE_POISONING_ZERO was removed in v5.11.
414 # Starting from v5.11 CONFIG_PAGE_POISONING unconditionally checks
415 # the 0xAA poison pattern on allocation.
416 # That brings higher performance penalty.
417 if arch in ('X86_64', 'ARM64', 'X86_32'):
418 stackleak_is_set = KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_STACKLEAK', 'y')
419 l += [stackleak_is_set]
420 l += [KconfigCheck('self_protection', 'kspp', 'RANDOMIZE_KSTACK_OFFSET_DEFAULT', 'y')]
421 if arch in ('X86_64', 'X86_32'):
422 l += [KconfigCheck('self_protection', 'kspp', 'DEFAULT_MMAP_MIN_ADDR', '65536')]
423 if arch in ('ARM64', 'ARM'):
424 l += [KconfigCheck('self_protection', 'kspp', 'DEFAULT_MMAP_MIN_ADDR', '32768')]
425 l += [KconfigCheck('self_protection', 'kspp', 'SYN_COOKIES', 'y')] # another reason?
427 l += [KconfigCheck('self_protection', 'kspp', 'ARM64_SW_TTBR0_PAN', 'y')]
429 l += [KconfigCheck('self_protection', 'kspp', 'PAGE_TABLE_ISOLATION', 'y')]
430 l += [KconfigCheck('self_protection', 'kspp', 'HIGHMEM64G', 'y')]
431 l += [KconfigCheck('self_protection', 'kspp', 'X86_PAE', 'y')]
433 # 'self_protection', 'maintainer'
434 ubsan_bounds_is_set = KconfigCheck('self_protection', 'maintainer', 'UBSAN_BOUNDS', 'y') # only array index bounds checking
435 l += [ubsan_bounds_is_set] # recommended by Kees Cook in /issues/53
436 if arch in ('X86_64', 'ARM64', 'X86_32'): # ARCH_HAS_UBSAN_SANITIZE_ALL is not enabled for ARM
437 l += [AND(KconfigCheck('self_protection', 'maintainer', 'UBSAN_SANITIZE_ALL', 'y'),
438 ubsan_bounds_is_set)] # recommended by Kees Cook in /issues/53
439 l += [AND(KconfigCheck('self_protection', 'maintainer', 'UBSAN_TRAP', 'y'),
440 ubsan_bounds_is_set)] # recommended by Kees Cook in /issues/53
442 # 'self_protection', 'clipos'
443 l += [KconfigCheck('self_protection', 'clipos', 'DEBUG_VIRTUAL', 'y')]
444 l += [KconfigCheck('self_protection', 'clipos', 'STATIC_USERMODEHELPER', 'y')] # needs userspace support
445 l += [OR(KconfigCheck('self_protection', 'clipos', 'EFI_DISABLE_PCI_DMA', 'y'),
447 l += [KconfigCheck('self_protection', 'clipos', 'SLAB_MERGE_DEFAULT', 'is not set')] # slab_nomerge
448 l += [KconfigCheck('self_protection', 'clipos', 'RANDOM_TRUST_BOOTLOADER', 'is not set')]
449 l += [KconfigCheck('self_protection', 'clipos', 'RANDOM_TRUST_CPU', 'is not set')]
450 l += [AND(KconfigCheck('self_protection', 'clipos', 'GCC_PLUGIN_RANDSTRUCT_PERFORMANCE', 'is not set'),
452 if arch in ('X86_64', 'ARM64', 'X86_32'):
453 l += [AND(KconfigCheck('self_protection', 'clipos', 'STACKLEAK_METRICS', 'is not set'),
455 l += [AND(KconfigCheck('self_protection', 'clipos', 'STACKLEAK_RUNTIME_DISABLE', 'is not set'),
457 if arch in ('X86_64', 'X86_32'):
458 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU_DEFAULT_ON', 'y'),
459 iommu_support_is_set)]
461 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU_SVM', 'y'),
462 iommu_support_is_set)]
464 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU', 'y'),
465 iommu_support_is_set)]
467 # 'self_protection', 'my'
468 l += [OR(KconfigCheck('self_protection', 'my', 'RESET_ATTACK_MITIGATION', 'y'),
469 efi_not_set)] # needs userspace support (systemd)
471 l += [KconfigCheck('self_protection', 'my', 'SLS', 'y')] # vs CVE-2021-26341 in Straight-Line-Speculation
472 l += [AND(KconfigCheck('self_protection', 'my', 'AMD_IOMMU_V2', 'y'),
473 iommu_support_is_set)]
475 l += [KconfigCheck('self_protection', 'my', 'SHADOW_CALL_STACK', 'y')] # depends on clang, maybe it's alternative to STACKPROTECTOR_STRONG
476 l += [KconfigCheck('self_protection', 'my', 'KASAN_HW_TAGS', 'y')]
477 cfi_clang_is_set = KconfigCheck('self_protection', 'my', 'CFI_CLANG', 'y')
478 l += [cfi_clang_is_set]
479 l += [AND(KconfigCheck('self_protection', 'my', 'CFI_PERMISSIVE', 'is not set'),
483 if arch in ('X86_64', 'ARM64', 'X86_32'):
484 l += [KconfigCheck('security_policy', 'defconfig', 'SECURITY', 'y')] # and choose your favourite LSM
486 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY', 'y')] # and choose your favourite LSM
487 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY_YAMA', 'y')]
488 l += [OR(KconfigCheck('security_policy', 'my', 'SECURITY_WRITABLE_HOOKS', 'is not set'),
489 KconfigCheck('security_policy', 'kspp', 'SECURITY_SELINUX_DISABLE', 'is not set'))]
490 l += [KconfigCheck('security_policy', 'clipos', 'SECURITY_LOCKDOWN_LSM', 'y')]
491 l += [KconfigCheck('security_policy', 'clipos', 'SECURITY_LOCKDOWN_LSM_EARLY', 'y')]
492 l += [KconfigCheck('security_policy', 'clipos', 'LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY', 'y')]
493 l += [KconfigCheck('security_policy', 'my', 'SECURITY_SAFESETID', 'y')]
494 loadpin_is_set = KconfigCheck('security_policy', 'my', 'SECURITY_LOADPIN', 'y')
495 l += [loadpin_is_set] # needs userspace support
496 l += [AND(KconfigCheck('security_policy', 'my', 'SECURITY_LOADPIN_ENFORCE', 'y'),
499 # 'cut_attack_surface', 'defconfig'
500 l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'BPF_UNPRIV_DEFAULT_OFF', 'y'),
501 bpf_syscall_not_set)] # see unprivileged_bpf_disabled
502 l += [KconfigCheck('cut_attack_surface', 'defconfig', 'SECCOMP', 'y')]
503 l += [KconfigCheck('cut_attack_surface', 'defconfig', 'SECCOMP_FILTER', 'y')]
504 if arch in ('X86_64', 'ARM64', 'X86_32'):
505 l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'STRICT_DEVMEM', 'y'),
506 devmem_not_set)] # refers to LOCKDOWN
508 # 'cut_attack_surface', 'kspp'
509 l += [KconfigCheck('cut_attack_surface', 'kspp', 'ACPI_CUSTOM_METHOD', 'is not set')] # refers to LOCKDOWN
510 l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_BRK', 'is not set')]
511 l += [KconfigCheck('cut_attack_surface', 'kspp', 'DEVKMEM', 'is not set')] # refers to LOCKDOWN
512 l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_VDSO', 'is not set')]
513 l += [KconfigCheck('cut_attack_surface', 'kspp', 'BINFMT_MISC', 'is not set')]
514 l += [KconfigCheck('cut_attack_surface', 'kspp', 'INET_DIAG', 'is not set')]
515 l += [KconfigCheck('cut_attack_surface', 'kspp', 'KEXEC', 'is not set')] # refers to LOCKDOWN
516 l += [KconfigCheck('cut_attack_surface', 'kspp', 'PROC_KCORE', 'is not set')] # refers to LOCKDOWN
517 l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_PTYS', 'is not set')]
518 l += [KconfigCheck('cut_attack_surface', 'kspp', 'HIBERNATION', 'is not set')] # refers to LOCKDOWN
519 l += [KconfigCheck('cut_attack_surface', 'kspp', 'IA32_EMULATION', 'is not set')]
520 l += [KconfigCheck('cut_attack_surface', 'kspp', 'X86_X32', 'is not set')]
521 l += [KconfigCheck('cut_attack_surface', 'kspp', 'MODIFY_LDT_SYSCALL', 'is not set')]
522 l += [KconfigCheck('cut_attack_surface', 'kspp', 'OABI_COMPAT', 'is not set')]
523 l += [modules_not_set]
524 l += [devmem_not_set]
525 l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'IO_STRICT_DEVMEM', 'y'),
526 devmem_not_set)] # refers to LOCKDOWN
528 l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'STRICT_DEVMEM', 'y'),
529 devmem_not_set)] # refers to LOCKDOWN
531 l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_VSYSCALL_NONE', 'y')] # 'vsyscall=none'
533 # 'cut_attack_surface', 'grsec'
534 l += [KconfigCheck('cut_attack_surface', 'grsec', 'ZSMALLOC_STAT', 'is not set')]
535 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PAGE_OWNER', 'is not set')]
536 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEBUG_KMEMLEAK', 'is not set')]
537 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BINFMT_AOUT', 'is not set')]
538 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KPROBE_EVENTS', 'is not set')]
539 l += [KconfigCheck('cut_attack_surface', 'grsec', 'UPROBE_EVENTS', 'is not set')]
540 l += [KconfigCheck('cut_attack_surface', 'grsec', 'GENERIC_TRACER', 'is not set')] # refers to LOCKDOWN
541 l += [KconfigCheck('cut_attack_surface', 'grsec', 'FUNCTION_TRACER', 'is not set')]
542 l += [KconfigCheck('cut_attack_surface', 'grsec', 'STACK_TRACER', 'is not set')]
543 l += [KconfigCheck('cut_attack_surface', 'grsec', 'HIST_TRIGGERS', 'is not set')]
544 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BLK_DEV_IO_TRACE', 'is not set')]
545 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROC_VMCORE', 'is not set')]
546 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROC_PAGE_MONITOR', 'is not set')]
547 l += [KconfigCheck('cut_attack_surface', 'grsec', 'USELIB', 'is not set')]
548 l += [KconfigCheck('cut_attack_surface', 'grsec', 'CHECKPOINT_RESTORE', 'is not set')]
549 l += [KconfigCheck('cut_attack_surface', 'grsec', 'USERFAULTFD', 'is not set')]
550 l += [KconfigCheck('cut_attack_surface', 'grsec', 'HWPOISON_INJECT', 'is not set')]
551 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MEM_SOFT_DIRTY', 'is not set')]
552 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEVPORT', 'is not set')] # refers to LOCKDOWN
553 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEBUG_FS', 'is not set')] # refers to LOCKDOWN
554 l += [KconfigCheck('cut_attack_surface', 'grsec', 'NOTIFIER_ERROR_INJECTION', 'is not set')]
555 l += [KconfigCheck('cut_attack_surface', 'grsec', 'FAIL_FUTEX', 'is not set')]
556 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PUNIT_ATOM_DEBUG', 'is not set')]
557 l += [KconfigCheck('cut_attack_surface', 'grsec', 'ACPI_CONFIGFS', 'is not set')]
558 l += [KconfigCheck('cut_attack_surface', 'grsec', 'EDAC_DEBUG', 'is not set')]
559 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DRM_I915_DEBUG', 'is not set')]
560 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BCACHE_CLOSURES_DEBUG', 'is not set')]
561 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DVB_C8SECTPFE', 'is not set')]
562 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MTD_SLRAM', 'is not set')]
563 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MTD_PHRAM', 'is not set')]
564 l += [KconfigCheck('cut_attack_surface', 'grsec', 'IO_URING', 'is not set')]
565 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KCMP', 'is not set')]
566 l += [KconfigCheck('cut_attack_surface', 'grsec', 'RSEQ', 'is not set')]
567 l += [KconfigCheck('cut_attack_surface', 'grsec', 'LATENCYTOP', 'is not set')]
568 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KCOV', 'is not set')]
569 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROVIDE_OHCI1394_DMA_INIT', 'is not set')]
570 l += [KconfigCheck('cut_attack_surface', 'grsec', 'SUNRPC_DEBUG', 'is not set')]
571 l += [AND(KconfigCheck('cut_attack_surface', 'grsec', 'PTDUMP_DEBUGFS', 'is not set'),
572 KconfigCheck('cut_attack_surface', 'grsec', 'X86_PTDUMP', 'is not set'))]
574 # 'cut_attack_surface', 'maintainer'
575 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'DRM_LEGACY', 'is not set')] # recommended by Daniel Vetter in /issues/38
576 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'FB', 'is not set')] # recommended by Daniel Vetter in /issues/38
577 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'VT', 'is not set')] # recommended by Daniel Vetter in /issues/38
578 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'BLK_DEV_FD', 'is not set')] # recommended by Denis Efremov in /pull/54
580 # 'cut_attack_surface', 'grapheneos'
581 l += [KconfigCheck('cut_attack_surface', 'grapheneos', 'AIO', 'is not set')]
583 # 'cut_attack_surface', 'clipos'
584 l += [KconfigCheck('cut_attack_surface', 'clipos', 'STAGING', 'is not set')]
585 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KSM', 'is not set')] # to prevent FLUSH+RELOAD attack
586 # l += [KconfigCheck('cut_attack_surface', 'clipos', 'IKCONFIG', 'is not set')] # no, IKCONFIG is needed for this check :)
587 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KALLSYMS', 'is not set')]
588 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_VSYSCALL_EMULATION', 'is not set')]
589 l += [KconfigCheck('cut_attack_surface', 'clipos', 'MAGIC_SYSRQ', 'is not set')]
590 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KEXEC_FILE', 'is not set')] # refers to LOCKDOWN (permissive)
591 l += [KconfigCheck('cut_attack_surface', 'clipos', 'USER_NS', 'is not set')] # user.max_user_namespaces=0
592 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_MSR', 'is not set')] # refers to LOCKDOWN
593 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_CPUID', 'is not set')]
594 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_IOPL_IOPERM', 'is not set')] # refers to LOCKDOWN
595 l += [KconfigCheck('cut_attack_surface', 'clipos', 'ACPI_TABLE_UPGRADE', 'is not set')] # refers to LOCKDOWN
596 l += [KconfigCheck('cut_attack_surface', 'clipos', 'EFI_CUSTOM_SSDT_OVERLAYS', 'is not set')]
597 l += [AND(KconfigCheck('cut_attack_surface', 'clipos', 'LDISC_AUTOLOAD', 'is not set'),
598 PresenceCheck('LDISC_AUTOLOAD', 'kconfig'))]
599 if arch in ('X86_64', 'X86_32'):
600 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_INTEL_TSX_MODE_OFF', 'y')] # tsx=off
602 # 'cut_attack_surface', 'lockdown'
603 l += [bpf_syscall_not_set] # refers to LOCKDOWN
604 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'EFI_TEST', 'is not set')] # refers to LOCKDOWN
605 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'MMIOTRACE_TEST', 'is not set')] # refers to LOCKDOWN
606 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'KPROBES', 'is not set')] # refers to LOCKDOWN
608 # 'cut_attack_surface', 'my'
609 l += [OR(KconfigCheck('cut_attack_surface', 'my', 'TRIM_UNUSED_KSYMS', 'y'),
611 l += [KconfigCheck('cut_attack_surface', 'my', 'MMIOTRACE', 'is not set')] # refers to LOCKDOWN (permissive)
612 l += [KconfigCheck('cut_attack_surface', 'my', 'LIVEPATCH', 'is not set')]
613 l += [KconfigCheck('cut_attack_surface', 'my', 'IP_DCCP', 'is not set')]
614 l += [KconfigCheck('cut_attack_surface', 'my', 'IP_SCTP', 'is not set')]
615 l += [KconfigCheck('cut_attack_surface', 'my', 'FTRACE', 'is not set')] # refers to LOCKDOWN
616 l += [KconfigCheck('cut_attack_surface', 'my', 'VIDEO_VIVID', 'is not set')]
617 l += [KconfigCheck('cut_attack_surface', 'my', 'INPUT_EVBUG', 'is not set')] # Can be used as a keylogger
620 if arch in ('X86_64', 'ARM64', 'X86_32'):
621 l += [KconfigCheck('harden_userspace', 'defconfig', 'INTEGRITY', 'y')]
623 l += [KconfigCheck('harden_userspace', 'my', 'INTEGRITY', 'y')]
625 l += [KconfigCheck('harden_userspace', 'defconfig', 'ARM64_MTE', 'y')]
626 if arch in ('ARM', 'X86_32'):
627 l += [KconfigCheck('harden_userspace', 'defconfig', 'VMSPLIT_3G', 'y')]
628 if arch in ('X86_64', 'ARM64'):
629 l += [KconfigCheck('harden_userspace', 'clipos', 'ARCH_MMAP_RND_BITS', '32')]
630 if arch in ('X86_32', 'ARM'):
631 l += [KconfigCheck('harden_userspace', 'my', 'ARCH_MMAP_RND_BITS', '16')]
633 # l += [KconfigCheck('feature_test', 'my', 'LKDTM', 'm')] # only for debugging!
636 def print_unknown_options(checklist, parsed_options):
640 if o1.type != 'complex':
641 known_options.append(o1.name)
644 if o2.type != 'complex':
645 if hasattr(o2, 'name'):
646 known_options.append(o2.name)
649 if o3.type == 'complex':
650 sys.exit('[!] ERROR: unexpected ComplexOptCheck inside {}'.format(o2.name))
651 if hasattr(o3, 'name'):
652 known_options.append(o3.name)
654 for option, value in parsed_options.items():
655 if option not in known_options:
656 print('[?] No check for option {} ({})'.format(option, value))
659 def print_checklist(mode, checklist, with_results):
663 output.append(o.json_dump(with_results))
664 print(json.dumps(output))
671 print('=' * sep_line_len)
672 print('{:^40}|{:^7}|{:^12}|{:^10}|{:^18}'.format('option name', 'type', 'desired val', 'decision', 'reason'), end='')
674 print('| {}'.format('check result'), end='')
676 print('=' * sep_line_len)
679 for opt in checklist:
681 if mode == 'show_ok':
682 if not opt.result.startswith('OK'):
684 if mode == 'show_fail':
685 if not opt.result.startswith('FAIL'):
687 opt.table_print(mode, with_results)
689 if mode == 'verbose':
690 print('-' * sep_line_len)
695 fail_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
697 ok_count = len(list(filter(lambda opt: opt.result.startswith('OK'), checklist)))
699 if mode == 'show_ok':
700 fail_suppressed = ' (suppressed in output)'
701 if mode == 'show_fail':
702 ok_suppressed = ' (suppressed in output)'
704 print('[+] Config check is finished: \'OK\' - {}{} / \'FAIL\' - {}{}'.format(ok_count, ok_suppressed, fail_count, fail_suppressed))
707 def populate_simple_opt_with_data(opt, data, data_type):
708 if opt.type == 'complex':
709 sys.exit('[!] ERROR: unexpected ComplexOptCheck {}: {}'.format(opt.name, vars(opt)))
710 if data_type not in TYPES_OF_CHECKS:
711 sys.exit('[!] ERROR: invalid data type "{}"'.format(data_type))
713 if data_type != opt.type:
716 if data_type == 'kconfig':
717 opt.state = data.get(opt.name, None)
718 elif data_type == 'version':
722 def populate_opt_with_data(opt, data, data_type):
723 if opt.type == 'complex':
725 if o.type == 'complex':
726 # Recursion for nested ComplexOptCheck objects
727 populate_opt_with_data(o, data, data_type)
729 populate_simple_opt_with_data(o, data, data_type)
731 if opt.type != 'kconfig':
732 sys.exit('[!] ERROR: bad type "{}" for a simple check {}'.format(opt.type, opt.name))
733 populate_simple_opt_with_data(opt, data, data_type)
736 def populate_with_data(checklist, data, data_type):
737 for opt in checklist:
738 populate_opt_with_data(opt, data, data_type)
741 def perform_checks(checklist):
742 for opt in checklist:
746 def parse_kconfig_file(parsed_options, fname):
747 with open(fname, 'r') as f:
748 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
749 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
751 for line in f.readlines():
756 if opt_is_on.match(line):
757 option, value = line.split('=', 1)
758 elif opt_is_off.match(line):
759 option, value = line[2:].split(' ', 1)
760 if value != 'is not set':
761 sys.exit('[!] ERROR: bad disabled kconfig option "{}"'.format(line))
763 if option in parsed_options:
764 sys.exit('[!] ERROR: kconfig option "{}" exists multiple times'.format(line))
767 parsed_options[option] = value
773 # - reporting about unknown kernel options in the kconfig
774 # - verbose printing of ComplexOptCheck items
775 # * json mode for printing the results in JSON format
776 report_modes = ['verbose', 'json', 'show_ok', 'show_fail']
777 supported_archs = ['X86_64', 'X86_32', 'ARM64', 'ARM']
778 parser = ArgumentParser(prog='kconfig-hardened-check',
779 description='A tool for checking the security hardening options of the Linux kernel')
780 parser.add_argument('--version', action='version', version='%(prog)s ' + __version__)
781 parser.add_argument('-p', '--print', choices=supported_archs,
782 help='print security hardening preferences for the selected architecture')
783 parser.add_argument('-c', '--config',
784 help='check the kernel kconfig file against these preferences')
785 parser.add_argument('-m', '--mode', choices=report_modes,
786 help='choose the report mode')
787 args = parser.parse_args()
793 print('[+] Special report mode: {}'.format(mode))
795 config_checklist = []
799 print('[+] Kconfig file to check: {}'.format(args.config))
801 arch, msg = detect_arch(args.config, supported_archs)
803 sys.exit('[!] ERROR: {}'.format(msg))
805 print('[+] Detected architecture: {}'.format(arch))
807 kernel_version, msg = detect_version(args.config)
808 if not kernel_version:
809 sys.exit('[!] ERROR: {}'.format(msg))
811 print('[+] Detected kernel version: {}.{}'.format(kernel_version[0], kernel_version[1]))
813 # add relevant kconfig checks to the checklist
814 add_kconfig_checks(config_checklist, arch)
816 # populate the checklist with the parsed kconfig data
817 parsed_kconfig_options = OrderedDict()
818 parse_kconfig_file(parsed_kconfig_options, args.config)
819 populate_with_data(config_checklist, parsed_kconfig_options, 'kconfig')
820 populate_with_data(config_checklist, kernel_version, 'version')
822 # now everything is ready for performing the checks
823 perform_checks(config_checklist)
825 # finally print the results
826 if mode == 'verbose':
827 print_unknown_options(config_checklist, parsed_kconfig_options)
828 print_checklist(mode, config_checklist, True)
833 if mode in ('show_ok', 'show_fail'):
834 sys.exit('[!] ERROR: wrong mode "{}" for --print'.format(mode))
836 add_kconfig_checks(config_checklist, arch)
838 print('[+] Printing kernel security hardening preferences for {}...'.format(arch))
839 print_checklist(mode, config_checklist, False)
845 if __name__ == '__main__':