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 if not reason or not decision or not name:
92 sys.exit('[!] ERROR: 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 sys.exit('[!] ERROR: empty {} check'.format(self.__class__.__name__))
190 if len(self.opts) == 1:
191 sys.exit('[!] ERROR: useless {} check'.format(self.__class__.__name__))
192 if not isinstance(opts[0], KconfigCheck) and not isinstance(opts[0], CmdlineCheck):
193 sys.exit('[!] ERROR: 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>)
244 sys.exit('[!] ERROR: invalid OR check')
245 for i, opt in enumerate(self.opts):
247 if opt.result.startswith('OK'):
248 self.result = opt.result
249 # Add more info for additional checks:
251 if opt.result == 'OK':
252 self.result = 'OK: {} "{}"'.format(opt.name, opt.expected)
253 elif opt.result == 'OK: not found':
254 self.result = 'OK: {} not found'.format(opt.name)
255 elif opt.result == 'OK: is present':
256 self.result = 'OK: {} is present'.format(opt.name)
257 # VersionCheck provides enough info
258 elif not opt.result.startswith('OK: version'):
259 sys.exit('[!] ERROR: unexpected OK description "{}"'.format(opt.result))
261 self.result = self.opts[0].result
264 class AND(ComplexOptCheck):
265 # self.opts[0] is the option that this AND-check is about.
267 # AND(<suboption>, <main_option>)
268 # Suboption is not checked if checking of the main_option is failed.
269 # AND(<X_is_disabled>, <old_X_is_disabled>)
271 for i, opt in reversed(list(enumerate(self.opts))):
274 self.result = opt.result
276 if not opt.result.startswith('OK'):
277 # This FAIL is caused by additional checks,
278 # and not by the main option that this AND-check is about.
279 # Describe the reason of the FAIL.
280 if opt.result.startswith('FAIL: \"') or opt.result == 'FAIL: not found':
281 self.result = 'FAIL: {} not "{}"'.format(opt.name, opt.expected)
282 elif opt.result == 'FAIL: not present':
283 self.result = 'FAIL: {} not present'.format(opt.name)
285 # VersionCheck provides enough info
286 self.result = opt.result
287 if not opt.result.startswith('FAIL: version'):
288 sys.exit('[!] ERROR: unexpected FAIL description "{}"'.format(opt.result))
290 sys.exit('[!] ERROR: invalid AND check')
293 def detect_arch(fname, archs):
294 with open(fname, 'r') as f:
295 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
297 for line in f.readlines():
298 if arch_pattern.match(line):
299 option, _ = line[7:].split('=', 1)
304 return None, 'more than one supported architecture is detected'
306 return None, 'failed to detect architecture'
310 def detect_version(fname):
311 with open(fname, 'r') as f:
312 ver_pattern = re.compile("# Linux/.* Kernel Configuration")
313 for line in f.readlines():
314 if ver_pattern.match(line):
318 ver_numbers = ver_str.split('.')
319 if len(ver_numbers) < 3 or not ver_numbers[0].isdigit() or not ver_numbers[1].isdigit():
320 msg = 'failed to parse the version "' + ver_str + '"'
322 return (int(ver_numbers[0]), int(ver_numbers[1])), None
323 return None, 'no kernel version detected'
326 def add_kconfig_checks(l, arch):
327 # Calling the KconfigCheck class constructor:
328 # KconfigCheck(reason, decision, name, expected)
330 modules_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'MODULES', 'is not set')
331 devmem_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'DEVMEM', 'is not set') # refers to LOCKDOWN
332 bpf_syscall_not_set = KconfigCheck('cut_attack_surface', 'lockdown', 'BPF_SYSCALL', 'is not set') # refers to LOCKDOWN
333 efi_not_set = KconfigCheck('cut_attack_surface', 'my', 'EFI', 'is not set')
335 # 'self_protection', 'defconfig'
336 l += [KconfigCheck('self_protection', 'defconfig', 'BUG', 'y')]
337 l += [KconfigCheck('self_protection', 'defconfig', 'SLUB_DEBUG', 'y')]
338 l += [KconfigCheck('self_protection', 'defconfig', 'GCC_PLUGINS', 'y')]
339 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR', 'y'),
340 KconfigCheck('self_protection', 'defconfig', 'CC_STACKPROTECTOR', 'y'))]
341 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR_STRONG', 'y'),
342 KconfigCheck('self_protection', 'defconfig', 'CC_STACKPROTECTOR_STRONG', 'y'))]
343 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STRICT_KERNEL_RWX', 'y'),
344 KconfigCheck('self_protection', 'defconfig', 'DEBUG_RODATA', 'y'))] # before v4.11
345 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STRICT_MODULE_RWX', 'y'),
346 KconfigCheck('self_protection', 'defconfig', 'DEBUG_SET_MODULE_RONX', 'y'),
347 modules_not_set)] # DEBUG_SET_MODULE_RONX was before v4.11
348 l += [OR(KconfigCheck('self_protection', 'defconfig', 'REFCOUNT_FULL', 'y'),
349 VersionCheck((5, 5)))] # REFCOUNT_FULL is enabled by default since v5.5
350 l += [KconfigCheck('self_protection', 'defconfig', 'THREAD_INFO_IN_TASK', 'y')]
351 iommu_support_is_set = KconfigCheck('self_protection', 'defconfig', 'IOMMU_SUPPORT', 'y')
352 l += [iommu_support_is_set] # is needed for mitigating DMA attacks
353 if arch in ('X86_64', 'ARM64', 'X86_32'):
354 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_BASE', 'y')]
355 if arch in ('X86_64', 'ARM64'):
356 l += [KconfigCheck('self_protection', 'defconfig', 'VMAP_STACK', 'y')]
357 if arch in ('X86_64', 'X86_32'):
358 l += [KconfigCheck('self_protection', 'defconfig', 'MICROCODE', 'y')] # is needed for mitigating CPU bugs
359 l += [KconfigCheck('self_protection', 'defconfig', 'RETPOLINE', 'y')]
360 l += [KconfigCheck('self_protection', 'defconfig', 'X86_SMAP', 'y')]
361 l += [KconfigCheck('self_protection', 'defconfig', 'SYN_COOKIES', 'y')] # another reason?
362 l += [OR(KconfigCheck('self_protection', 'defconfig', 'X86_UMIP', 'y'),
363 KconfigCheck('self_protection', 'defconfig', 'X86_INTEL_UMIP', 'y'))]
364 if arch in ('ARM64', 'ARM'):
365 l += [KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR_PER_TASK', 'y')]
367 l += [KconfigCheck('self_protection', 'defconfig', 'PAGE_TABLE_ISOLATION', 'y')]
368 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_MEMORY', 'y')]
369 l += [AND(KconfigCheck('self_protection', 'defconfig', 'INTEL_IOMMU', 'y'),
370 iommu_support_is_set)]
371 l += [AND(KconfigCheck('self_protection', 'defconfig', 'AMD_IOMMU', 'y'),
372 iommu_support_is_set)]
374 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_PAN', 'y')]
375 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_EPAN', 'y')]
376 l += [KconfigCheck('self_protection', 'defconfig', 'UNMAP_KERNEL_AT_EL0', 'y')]
377 l += [OR(KconfigCheck('self_protection', 'defconfig', 'HARDEN_EL2_VECTORS', 'y'),
378 AND(KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_BASE', 'y'),
379 VersionCheck((5, 9))))] # HARDEN_EL2_VECTORS was included in RANDOMIZE_BASE in v5.9
380 l += [KconfigCheck('self_protection', 'defconfig', 'RODATA_FULL_DEFAULT_ENABLED', 'y')]
381 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_PTR_AUTH_KERNEL', 'y')]
382 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_BTI_KERNEL', 'y')]
383 l += [OR(KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_PREDICTOR', 'y'),
384 VersionCheck((5, 10)))] # HARDEN_BRANCH_PREDICTOR is enabled by default since v5.10
385 l += [KconfigCheck('self_protection', 'defconfig', 'MITIGATE_SPECTRE_BRANCH_HISTORY', 'y')]
386 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_MTE', 'y')]
387 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_MODULE_REGION_FULL', 'y')]
389 l += [KconfigCheck('self_protection', 'defconfig', 'CPU_SW_DOMAIN_PAN', 'y')]
390 l += [KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_PREDICTOR', 'y')]
391 l += [KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_HISTORY', 'y')]
393 # 'self_protection', 'kspp'
394 l += [KconfigCheck('self_protection', 'kspp', 'SECURITY_DMESG_RESTRICT', 'y')]
395 l += [KconfigCheck('self_protection', 'kspp', 'BUG_ON_DATA_CORRUPTION', 'y')]
396 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_WX', 'y')]
397 l += [KconfigCheck('self_protection', 'kspp', 'SCHED_STACK_END_CHECK', 'y')]
398 l += [KconfigCheck('self_protection', 'kspp', 'SLAB_FREELIST_HARDENED', 'y')]
399 l += [KconfigCheck('self_protection', 'kspp', 'SLAB_FREELIST_RANDOM', 'y')]
400 l += [KconfigCheck('self_protection', 'kspp', 'SHUFFLE_PAGE_ALLOCATOR', 'y')]
401 l += [KconfigCheck('self_protection', 'kspp', 'FORTIFY_SOURCE', 'y')]
402 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_LIST', 'y')]
403 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_SG', 'y')]
404 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_CREDENTIALS', 'y')]
405 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_NOTIFIERS', 'y')]
406 l += [KconfigCheck('self_protection', 'kspp', 'INIT_ON_ALLOC_DEFAULT_ON', 'y')]
407 l += [KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_LATENT_ENTROPY', 'y')]
408 l += [KconfigCheck('self_protection', 'kspp', 'KFENCE', 'y')]
409 l += [KconfigCheck('self_protection', 'kspp', 'WERROR', 'y')]
410 l += [KconfigCheck('self_protection', 'kspp', 'IOMMU_DEFAULT_DMA_STRICT', 'y')]
411 l += [KconfigCheck('self_protection', 'kspp', 'ZERO_CALL_USED_REGS', 'y')]
412 randstruct_is_set = KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_RANDSTRUCT', 'y')
413 l += [randstruct_is_set]
414 hardened_usercopy_is_set = KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY', 'y')
415 l += [hardened_usercopy_is_set]
416 l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_FALLBACK', 'is not set'),
417 hardened_usercopy_is_set)]
418 l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_PAGESPAN', 'is not set'),
419 hardened_usercopy_is_set)]
420 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG', 'y'),
422 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_ALL', 'y'),
424 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_SHA512', 'y'),
426 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_FORCE', 'y'),
427 modules_not_set)] # refers to LOCKDOWN
428 l += [OR(KconfigCheck('self_protection', 'kspp', 'INIT_STACK_ALL_ZERO', 'y'),
429 KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_STRUCTLEAK_BYREF_ALL', 'y'))]
430 l += [OR(KconfigCheck('self_protection', 'kspp', 'INIT_ON_FREE_DEFAULT_ON', 'y'),
431 KconfigCheck('self_protection', 'kspp', 'PAGE_POISONING_ZERO', 'y'))]
432 # CONFIG_INIT_ON_FREE_DEFAULT_ON was added in v5.3.
433 # CONFIG_PAGE_POISONING_ZERO was removed in v5.11.
434 # Starting from v5.11 CONFIG_PAGE_POISONING unconditionally checks
435 # the 0xAA poison pattern on allocation.
436 # That brings higher performance penalty.
437 if arch in ('X86_64', 'ARM64', 'X86_32'):
438 stackleak_is_set = KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_STACKLEAK', 'y')
439 l += [stackleak_is_set]
440 l += [OR(KconfigCheck('self_protection', 'kspp', 'RANDOMIZE_KSTACK_OFFSET_DEFAULT', 'y'),
441 CmdlineCheck('self_protection', 'kspp', 'randomize_kstack_offset', '1'))]
442 if arch in ('X86_64', 'X86_32'):
443 l += [KconfigCheck('self_protection', 'kspp', 'SCHED_CORE', 'y')]
444 l += [KconfigCheck('self_protection', 'kspp', 'DEFAULT_MMAP_MIN_ADDR', '65536')]
445 if arch in ('ARM64', 'ARM'):
446 l += [KconfigCheck('self_protection', 'kspp', 'DEFAULT_MMAP_MIN_ADDR', '32768')]
447 l += [KconfigCheck('self_protection', 'kspp', 'SYN_COOKIES', 'y')] # another reason?
449 l += [KconfigCheck('self_protection', 'kspp', 'ARM64_SW_TTBR0_PAN', 'y')]
451 l += [KconfigCheck('self_protection', 'kspp', 'PAGE_TABLE_ISOLATION', 'y')]
452 l += [KconfigCheck('self_protection', 'kspp', 'HIGHMEM64G', 'y')]
453 l += [KconfigCheck('self_protection', 'kspp', 'X86_PAE', 'y')]
455 # 'self_protection', 'maintainer'
456 ubsan_bounds_is_set = KconfigCheck('self_protection', 'maintainer', 'UBSAN_BOUNDS', 'y') # only array index bounds checking
457 l += [ubsan_bounds_is_set] # recommended by Kees Cook in /issues/53
458 if arch in ('X86_64', 'ARM64', 'X86_32'): # ARCH_HAS_UBSAN_SANITIZE_ALL is not enabled for ARM
459 l += [AND(KconfigCheck('self_protection', 'maintainer', 'UBSAN_SANITIZE_ALL', 'y'),
460 ubsan_bounds_is_set)] # recommended by Kees Cook in /issues/53
461 l += [AND(KconfigCheck('self_protection', 'maintainer', 'UBSAN_TRAP', 'y'),
462 ubsan_bounds_is_set)] # recommended by Kees Cook in /issues/53
464 # 'self_protection', 'clipos'
465 l += [KconfigCheck('self_protection', 'clipos', 'DEBUG_VIRTUAL', 'y')]
466 l += [KconfigCheck('self_protection', 'clipos', 'STATIC_USERMODEHELPER', 'y')] # needs userspace support
467 l += [OR(KconfigCheck('self_protection', 'clipos', 'EFI_DISABLE_PCI_DMA', 'y'),
469 l += [OR(KconfigCheck('self_protection', 'clipos', 'SLAB_MERGE_DEFAULT', 'is not set'),
470 CmdlineCheck('self_protection', 'kspp', 'slab_nomerge'))] # option presence check
471 l += [KconfigCheck('self_protection', 'clipos', 'RANDOM_TRUST_BOOTLOADER', 'is not set')]
472 l += [KconfigCheck('self_protection', 'clipos', 'RANDOM_TRUST_CPU', 'is not set')]
473 l += [AND(KconfigCheck('self_protection', 'clipos', 'GCC_PLUGIN_RANDSTRUCT_PERFORMANCE', 'is not set'),
475 if arch in ('X86_64', 'ARM64', 'X86_32'):
476 l += [AND(KconfigCheck('self_protection', 'clipos', 'STACKLEAK_METRICS', 'is not set'),
478 l += [AND(KconfigCheck('self_protection', 'clipos', 'STACKLEAK_RUNTIME_DISABLE', 'is not set'),
480 if arch in ('X86_64', 'X86_32'):
481 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU_DEFAULT_ON', 'y'),
482 iommu_support_is_set)]
484 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU_SVM', 'y'),
485 iommu_support_is_set)]
487 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU', 'y'),
488 iommu_support_is_set)]
490 # 'self_protection', 'my'
491 l += [OR(KconfigCheck('self_protection', 'my', 'RESET_ATTACK_MITIGATION', 'y'),
492 efi_not_set)] # needs userspace support (systemd)
494 l += [KconfigCheck('self_protection', 'my', 'SLS', 'y')] # vs CVE-2021-26341 in Straight-Line-Speculation
495 l += [AND(KconfigCheck('self_protection', 'my', 'AMD_IOMMU_V2', 'y'),
496 iommu_support_is_set)]
498 l += [KconfigCheck('self_protection', 'my', 'SHADOW_CALL_STACK', 'y')] # depends on clang, maybe it's alternative to STACKPROTECTOR_STRONG
499 l += [KconfigCheck('self_protection', 'my', 'KASAN_HW_TAGS', 'y')]
500 cfi_clang_is_set = KconfigCheck('self_protection', 'my', 'CFI_CLANG', 'y')
501 l += [cfi_clang_is_set]
502 l += [AND(KconfigCheck('self_protection', 'my', 'CFI_PERMISSIVE', 'is not set'),
506 if arch in ('X86_64', 'ARM64', 'X86_32'):
507 l += [KconfigCheck('security_policy', 'defconfig', 'SECURITY', 'y')] # and choose your favourite LSM
509 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY', 'y')] # and choose your favourite LSM
510 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY_YAMA', 'y')]
511 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY_SELINUX_DISABLE', 'is not set')]
512 l += [KconfigCheck('security_policy', 'clipos', 'SECURITY_LOCKDOWN_LSM', 'y')]
513 l += [KconfigCheck('security_policy', 'clipos', 'SECURITY_LOCKDOWN_LSM_EARLY', 'y')]
514 l += [KconfigCheck('security_policy', 'clipos', 'LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY', 'y')]
515 l += [KconfigCheck('security_policy', 'my', 'SECURITY_WRITABLE_HOOKS', 'is not set')] # refers to SECURITY_SELINUX_DISABLE
516 l += [KconfigCheck('security_policy', 'my', 'SECURITY_SAFESETID', 'y')]
517 loadpin_is_set = KconfigCheck('security_policy', 'my', 'SECURITY_LOADPIN', 'y')
518 l += [loadpin_is_set] # needs userspace support
519 l += [AND(KconfigCheck('security_policy', 'my', 'SECURITY_LOADPIN_ENFORCE', 'y'),
522 # 'cut_attack_surface', 'defconfig'
523 l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'BPF_UNPRIV_DEFAULT_OFF', 'y'),
524 bpf_syscall_not_set)] # see unprivileged_bpf_disabled
525 l += [KconfigCheck('cut_attack_surface', 'defconfig', 'SECCOMP', 'y')]
526 l += [KconfigCheck('cut_attack_surface', 'defconfig', 'SECCOMP_FILTER', 'y')]
527 if arch in ('X86_64', 'ARM64', 'X86_32'):
528 l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'STRICT_DEVMEM', 'y'),
529 devmem_not_set)] # refers to LOCKDOWN
531 # 'cut_attack_surface', 'kspp'
532 l += [KconfigCheck('cut_attack_surface', 'kspp', 'ACPI_CUSTOM_METHOD', 'is not set')] # refers to LOCKDOWN
533 l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_BRK', 'is not set')]
534 l += [KconfigCheck('cut_attack_surface', 'kspp', 'DEVKMEM', 'is not set')] # refers to LOCKDOWN
535 l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_VDSO', 'is not set')]
536 l += [KconfigCheck('cut_attack_surface', 'kspp', 'BINFMT_MISC', 'is not set')]
537 l += [KconfigCheck('cut_attack_surface', 'kspp', 'INET_DIAG', 'is not set')]
538 l += [KconfigCheck('cut_attack_surface', 'kspp', 'KEXEC', 'is not set')] # refers to LOCKDOWN
539 l += [KconfigCheck('cut_attack_surface', 'kspp', 'PROC_KCORE', 'is not set')] # refers to LOCKDOWN
540 l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_PTYS', 'is not set')]
541 l += [KconfigCheck('cut_attack_surface', 'kspp', 'HIBERNATION', 'is not set')] # refers to LOCKDOWN
542 l += [KconfigCheck('cut_attack_surface', 'kspp', 'IA32_EMULATION', 'is not set')]
543 l += [KconfigCheck('cut_attack_surface', 'kspp', 'X86_X32', 'is not set')]
544 l += [KconfigCheck('cut_attack_surface', 'kspp', 'MODIFY_LDT_SYSCALL', 'is not set')]
545 l += [KconfigCheck('cut_attack_surface', 'kspp', 'OABI_COMPAT', 'is not set')]
546 l += [KconfigCheck('cut_attack_surface', 'kspp', 'X86_MSR', 'is not set')] # refers to LOCKDOWN
547 l += [modules_not_set]
548 l += [devmem_not_set]
549 l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'IO_STRICT_DEVMEM', 'y'),
550 devmem_not_set)] # refers to LOCKDOWN
552 l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'STRICT_DEVMEM', 'y'),
553 devmem_not_set)] # refers to LOCKDOWN
555 l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_VSYSCALL_NONE', 'y')] # 'vsyscall=none'
557 # 'cut_attack_surface', 'grsec'
558 l += [KconfigCheck('cut_attack_surface', 'grsec', 'ZSMALLOC_STAT', 'is not set')]
559 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PAGE_OWNER', 'is not set')]
560 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEBUG_KMEMLEAK', 'is not set')]
561 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BINFMT_AOUT', 'is not set')]
562 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KPROBE_EVENTS', 'is not set')]
563 l += [KconfigCheck('cut_attack_surface', 'grsec', 'UPROBE_EVENTS', 'is not set')]
564 l += [KconfigCheck('cut_attack_surface', 'grsec', 'GENERIC_TRACER', 'is not set')] # refers to LOCKDOWN
565 l += [KconfigCheck('cut_attack_surface', 'grsec', 'FUNCTION_TRACER', 'is not set')]
566 l += [KconfigCheck('cut_attack_surface', 'grsec', 'STACK_TRACER', 'is not set')]
567 l += [KconfigCheck('cut_attack_surface', 'grsec', 'HIST_TRIGGERS', 'is not set')]
568 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BLK_DEV_IO_TRACE', 'is not set')]
569 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROC_VMCORE', 'is not set')]
570 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROC_PAGE_MONITOR', 'is not set')]
571 l += [KconfigCheck('cut_attack_surface', 'grsec', 'USELIB', 'is not set')]
572 l += [KconfigCheck('cut_attack_surface', 'grsec', 'CHECKPOINT_RESTORE', 'is not set')]
573 l += [KconfigCheck('cut_attack_surface', 'grsec', 'USERFAULTFD', 'is not set')]
574 l += [KconfigCheck('cut_attack_surface', 'grsec', 'HWPOISON_INJECT', 'is not set')]
575 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MEM_SOFT_DIRTY', 'is not set')]
576 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEVPORT', 'is not set')] # refers to LOCKDOWN
577 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEBUG_FS', 'is not set')] # refers to LOCKDOWN
578 l += [KconfigCheck('cut_attack_surface', 'grsec', 'NOTIFIER_ERROR_INJECTION', 'is not set')]
579 l += [KconfigCheck('cut_attack_surface', 'grsec', 'FAIL_FUTEX', 'is not set')]
580 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PUNIT_ATOM_DEBUG', 'is not set')]
581 l += [KconfigCheck('cut_attack_surface', 'grsec', 'ACPI_CONFIGFS', 'is not set')]
582 l += [KconfigCheck('cut_attack_surface', 'grsec', 'EDAC_DEBUG', 'is not set')]
583 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DRM_I915_DEBUG', 'is not set')]
584 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BCACHE_CLOSURES_DEBUG', 'is not set')]
585 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DVB_C8SECTPFE', 'is not set')]
586 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MTD_SLRAM', 'is not set')]
587 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MTD_PHRAM', 'is not set')]
588 l += [KconfigCheck('cut_attack_surface', 'grsec', 'IO_URING', 'is not set')]
589 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KCMP', 'is not set')]
590 l += [KconfigCheck('cut_attack_surface', 'grsec', 'RSEQ', 'is not set')]
591 l += [KconfigCheck('cut_attack_surface', 'grsec', 'LATENCYTOP', 'is not set')]
592 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KCOV', 'is not set')]
593 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROVIDE_OHCI1394_DMA_INIT', 'is not set')]
594 l += [KconfigCheck('cut_attack_surface', 'grsec', 'SUNRPC_DEBUG', 'is not set')]
595 l += [AND(KconfigCheck('cut_attack_surface', 'grsec', 'PTDUMP_DEBUGFS', 'is not set'),
596 KconfigCheck('cut_attack_surface', 'grsec', 'X86_PTDUMP', 'is not set'))]
598 # 'cut_attack_surface', 'maintainer'
599 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'DRM_LEGACY', 'is not set')] # recommended by Daniel Vetter in /issues/38
600 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'FB', 'is not set')] # recommended by Daniel Vetter in /issues/38
601 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'VT', 'is not set')] # recommended by Daniel Vetter in /issues/38
602 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'BLK_DEV_FD', 'is not set')] # recommended by Denis Efremov in /pull/54
603 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'BLK_DEV_FD_RAWCMD', 'is not set')] # recommended by Denis Efremov in /pull/62
605 # 'cut_attack_surface', 'grapheneos'
606 l += [KconfigCheck('cut_attack_surface', 'grapheneos', 'AIO', 'is not set')]
608 # 'cut_attack_surface', 'clipos'
609 l += [KconfigCheck('cut_attack_surface', 'clipos', 'STAGING', 'is not set')]
610 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KSM', 'is not set')] # to prevent FLUSH+RELOAD attack
611 # l += [KconfigCheck('cut_attack_surface', 'clipos', 'IKCONFIG', 'is not set')] # no, IKCONFIG is needed for this check :)
612 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KALLSYMS', 'is not set')]
613 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_VSYSCALL_EMULATION', 'is not set')]
614 l += [KconfigCheck('cut_attack_surface', 'clipos', 'MAGIC_SYSRQ', 'is not set')]
615 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KEXEC_FILE', 'is not set')] # refers to LOCKDOWN (permissive)
616 l += [KconfigCheck('cut_attack_surface', 'clipos', 'USER_NS', 'is not set')] # user.max_user_namespaces=0
617 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_CPUID', 'is not set')]
618 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_IOPL_IOPERM', 'is not set')] # refers to LOCKDOWN
619 l += [KconfigCheck('cut_attack_surface', 'clipos', 'ACPI_TABLE_UPGRADE', 'is not set')] # refers to LOCKDOWN
620 l += [KconfigCheck('cut_attack_surface', 'clipos', 'EFI_CUSTOM_SSDT_OVERLAYS', 'is not set')]
621 l += [AND(KconfigCheck('cut_attack_surface', 'clipos', 'LDISC_AUTOLOAD', 'is not set'),
622 KconfigCheck('cut_attack_surface', 'clipos', 'LDISC_AUTOLOAD'))] # option presence check
623 if arch in ('X86_64', 'X86_32'):
624 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_INTEL_TSX_MODE_OFF', 'y')] # tsx=off
626 # 'cut_attack_surface', 'lockdown'
627 l += [bpf_syscall_not_set] # refers to LOCKDOWN
628 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'EFI_TEST', 'is not set')] # refers to LOCKDOWN
629 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'MMIOTRACE_TEST', 'is not set')] # refers to LOCKDOWN
630 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'KPROBES', 'is not set')] # refers to LOCKDOWN
632 # 'cut_attack_surface', 'my'
633 l += [OR(KconfigCheck('cut_attack_surface', 'my', 'TRIM_UNUSED_KSYMS', 'y'),
635 l += [KconfigCheck('cut_attack_surface', 'my', 'MMIOTRACE', 'is not set')] # refers to LOCKDOWN (permissive)
636 l += [KconfigCheck('cut_attack_surface', 'my', 'LIVEPATCH', 'is not set')]
637 l += [KconfigCheck('cut_attack_surface', 'my', 'IP_DCCP', 'is not set')]
638 l += [KconfigCheck('cut_attack_surface', 'my', 'IP_SCTP', 'is not set')]
639 l += [KconfigCheck('cut_attack_surface', 'my', 'FTRACE', 'is not set')] # refers to LOCKDOWN
640 l += [KconfigCheck('cut_attack_surface', 'my', 'VIDEO_VIVID', 'is not set')]
641 l += [KconfigCheck('cut_attack_surface', 'my', 'INPUT_EVBUG', 'is not set')] # Can be used as a keylogger
642 l += [KconfigCheck('cut_attack_surface', 'my', 'KGDB', 'is not set')]
645 if arch in ('X86_64', 'ARM64', 'X86_32'):
646 l += [KconfigCheck('harden_userspace', 'defconfig', 'INTEGRITY', 'y')]
648 l += [KconfigCheck('harden_userspace', 'my', 'INTEGRITY', 'y')]
649 if arch in ('ARM', 'X86_32'):
650 l += [KconfigCheck('harden_userspace', 'defconfig', 'VMSPLIT_3G', 'y')]
651 if arch in ('X86_64', 'ARM64'):
652 l += [KconfigCheck('harden_userspace', 'clipos', 'ARCH_MMAP_RND_BITS', '32')]
653 if arch in ('X86_32', 'ARM'):
654 l += [KconfigCheck('harden_userspace', 'my', 'ARCH_MMAP_RND_BITS', '16')]
656 # l += [KconfigCheck('feature_test', 'my', 'LKDTM', 'm')] # only for debugging!
659 def add_cmdline_checks(l, arch):
660 # Calling the CmdlineCheck class constructor:
661 # CmdlineCheck(reason, decision, name, expected)
663 if arch in ('X86_64', 'X86_32'):
664 l += [CmdlineCheck('self_protection', 'kspp', 'pti', 'on')]
668 def print_unknown_options(checklist, parsed_options):
672 if o1.type != 'complex':
673 known_options.append(o1.name)
676 if o2.type != 'complex':
677 if hasattr(o2, 'name'):
678 known_options.append(o2.name)
681 if o3.type == 'complex':
682 sys.exit('[!] ERROR: unexpected ComplexOptCheck inside {}'.format(o2.name))
683 if hasattr(o3, 'name'):
684 known_options.append(o3.name)
686 for option, value in parsed_options.items():
687 if option not in known_options:
688 print('[?] No check for option {} ({})'.format(option, value))
691 def print_checklist(mode, checklist, with_results):
695 output.append(o.json_dump(with_results))
696 print(json.dumps(output))
703 print('=' * sep_line_len)
704 print('{:^40}|{:^7}|{:^12}|{:^10}|{:^18}'.format('option name', 'type', 'desired val', 'decision', 'reason'), end='')
706 print('| {}'.format('check result'), end='')
708 print('=' * sep_line_len)
711 for opt in checklist:
713 if mode == 'show_ok':
714 if not opt.result.startswith('OK'):
716 if mode == 'show_fail':
717 if not opt.result.startswith('FAIL'):
719 opt.table_print(mode, with_results)
721 if mode == 'verbose':
722 print('-' * sep_line_len)
727 fail_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
729 ok_count = len(list(filter(lambda opt: opt.result.startswith('OK'), checklist)))
731 if mode == 'show_ok':
732 fail_suppressed = ' (suppressed in output)'
733 if mode == 'show_fail':
734 ok_suppressed = ' (suppressed in output)'
736 print('[+] Config check is finished: \'OK\' - {}{} / \'FAIL\' - {}{}'.format(ok_count, ok_suppressed, fail_count, fail_suppressed))
739 def populate_simple_opt_with_data(opt, data, data_type):
740 if opt.type == 'complex':
741 sys.exit('[!] ERROR: unexpected ComplexOptCheck {}: {}'.format(opt.name, vars(opt)))
742 if opt.type not in SIMPLE_OPTION_TYPES:
743 sys.exit('[!] ERROR: invalid opt type "{}" for {}'.format(opt.type, opt.name))
744 if data_type not in SIMPLE_OPTION_TYPES:
745 sys.exit('[!] ERROR: invalid data type "{}"'.format(data_type))
747 if data_type != opt.type:
750 if data_type in ('kconfig', 'cmdline'):
751 opt.state = data.get(opt.name, None)
752 elif data_type == 'version':
755 sys.exit('[!] ERROR: unexpected data type "{}"'.format(data_type))
758 def populate_opt_with_data(opt, data, data_type):
759 if opt.type == 'complex':
761 if o.type == 'complex':
762 # Recursion for nested ComplexOptCheck objects
763 populate_opt_with_data(o, data, data_type)
765 populate_simple_opt_with_data(o, data, data_type)
767 if opt.type not in ('kconfig', 'cmdline'):
768 sys.exit('[!] ERROR: bad type "{}" for a simple check {}'.format(opt.type, opt.name))
769 populate_simple_opt_with_data(opt, data, data_type)
772 def populate_with_data(checklist, data, data_type):
773 for opt in checklist:
774 populate_opt_with_data(opt, data, data_type)
777 def perform_checks(checklist):
778 for opt in checklist:
782 def parse_kconfig_file(parsed_options, fname):
783 with open(fname, 'r') as f:
784 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
785 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
787 for line in f.readlines():
792 if opt_is_on.match(line):
793 option, value = line.split('=', 1)
794 elif opt_is_off.match(line):
795 option, value = line[2:].split(' ', 1)
796 if value != 'is not set':
797 sys.exit('[!] ERROR: bad disabled kconfig option "{}"'.format(line))
799 if option in parsed_options:
800 sys.exit('[!] ERROR: kconfig option "{}" exists multiple times'.format(line))
803 parsed_options[option] = value
806 def parse_cmdline_file(parsed_options, fname):
807 with open(fname, 'r') as f:
813 sys.exit('[!] ERROR: more than one line in "{}"'.format(fname))
817 name, value = opt.split('=', 1)
820 value = '' # '' is not None
821 parsed_options[name] = value
827 # - reporting about unknown kernel options in the kconfig
828 # - verbose printing of ComplexOptCheck items
829 # * json mode for printing the results in JSON format
830 report_modes = ['verbose', 'json', 'show_ok', 'show_fail']
831 supported_archs = ['X86_64', 'X86_32', 'ARM64', 'ARM']
832 parser = ArgumentParser(prog='kconfig-hardened-check',
833 description='A tool for checking the security hardening options of the Linux kernel')
834 parser.add_argument('--version', action='version', version='%(prog)s ' + __version__)
835 parser.add_argument('-p', '--print', choices=supported_archs,
836 help='print security hardening preferences for the selected architecture')
837 parser.add_argument('-c', '--config',
838 help='check the kernel kconfig file against these preferences')
839 parser.add_argument('-l', '--cmdline',
840 help='check the kernel cmdline file against these preferences')
841 parser.add_argument('-m', '--mode', choices=report_modes,
842 help='choose the report mode')
843 args = parser.parse_args()
849 print('[+] Special report mode: {}'.format(mode))
851 config_checklist = []
855 print('[+] Kconfig file to check: {}'.format(args.config))
857 print('[+] Kernel cmdline file to check: {}'.format(args.cmdline))
859 arch, msg = detect_arch(args.config, supported_archs)
861 sys.exit('[!] ERROR: {}'.format(msg))
863 print('[+] Detected architecture: {}'.format(arch))
865 kernel_version, msg = detect_version(args.config)
866 if not kernel_version:
867 sys.exit('[!] ERROR: {}'.format(msg))
869 print('[+] Detected kernel version: {}.{}'.format(kernel_version[0], kernel_version[1]))
871 # add relevant kconfig checks to the checklist
872 add_kconfig_checks(config_checklist, arch)
874 # populate the checklist with the parsed kconfig data
875 parsed_kconfig_options = OrderedDict()
876 parse_kconfig_file(parsed_kconfig_options, args.config)
877 populate_with_data(config_checklist, parsed_kconfig_options, 'kconfig')
878 populate_with_data(config_checklist, kernel_version, 'version')
881 # add relevant cmdline checks to the checklist
882 add_cmdline_checks(config_checklist, arch)
884 # populate the checklist with the parsed kconfig data
885 parsed_cmdline_options = OrderedDict()
886 parse_cmdline_file(parsed_cmdline_options, args.cmdline)
887 populate_with_data(config_checklist, parsed_cmdline_options, 'cmdline')
889 # now everything is ready for performing the checks
890 perform_checks(config_checklist)
892 # finally print the results
893 if mode == 'verbose':
894 print_unknown_options(config_checklist, parsed_kconfig_options)
895 print_checklist(mode, config_checklist, True)
899 sys.exit('[!] ERROR: checking cmdline doesn\'t work without checking kconfig')
902 if mode in ('show_ok', 'show_fail'):
903 sys.exit('[!] ERROR: wrong mode "{}" for --print'.format(mode))
905 add_kconfig_checks(config_checklist, arch)
906 add_cmdline_checks(config_checklist, arch)
908 print('[+] Printing kernel security hardening preferences for {}...'.format(arch))
909 print_checklist(mode, config_checklist, False)
915 if __name__ == '__main__':