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)
20 # debugfs=no-mount (or off if possible)
22 # Mitigations of CPU vulnerabilities:
24 # mitigations=auto,nosmt (nosmt is slow)
27 # spec_store_bypass_disable=on
29 # l1d_flush=on (a part of the l1tf option)
39 # sysrq_always_enabled
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
59 # vm.unprivileged_userfaultfd=0
60 # (at first, it disabled unprivileged userfaultfd,
61 # and since v5.11 it enables unprivileged userfaultfd for user-mode only)
62 # dev.tty.ldisc_autoload=0
63 # fs.protected_symlinks=1
64 # fs.protected_hardlinks=1
65 # fs.protected_fifos=2
66 # fs.protected_regular=2
68 # kernel.modules_disabled=1
69 # kernel.randomize_va_space = 2
72 # pylint: disable=missing-module-docstring,missing-class-docstring,missing-function-docstring
73 # pylint: disable=line-too-long,invalid-name,too-many-branches,too-many-statements
77 from argparse import ArgumentParser
78 from collections import OrderedDict
81 from .__about__ import __version__
83 SIMPLE_OPTION_TYPES = ('kconfig', 'version', 'cmdline')
86 # Constructor without the 'expected' parameter is for option presence checks (any value is OK)
87 def __init__(self, reason, decision, name, expected=None):
88 assert(reason and decision and name), \
89 'invalid {} check for "{}"'.format(self.__class__.__name__, name)
91 self.expected = expected
92 self.decision = decision
102 # handle the option presence check
103 if self.expected is None:
104 if self.state is None:
105 self.result = 'FAIL: not present'
107 self.result = 'OK: is present'
110 # handle the option value check
111 if self.expected == self.state:
113 elif self.state is None:
114 if self.expected == 'is not set':
115 self.result = 'OK: not found'
117 self.result = 'FAIL: not found'
119 self.result = 'FAIL: "' + self.state + '"'
121 def table_print(self, _mode, with_results):
122 if self.expected is None:
125 expected = self.expected
126 print('{:<40}|{:^7}|{:^12}|{:^10}|{:^18}'.format(self.name, self.type, expected, self.decision, self.reason), end='')
128 print('| {}'.format(self.result), end='')
130 def json_dump(self, with_results):
131 dump = [self.name, self.type, self.expected, self.decision, self.reason]
133 dump.append(self.result)
137 class KconfigCheck(OptCheck):
138 def __init__(self, *args, **kwargs):
139 super().__init__(*args, **kwargs)
140 self.name = 'CONFIG_' + self.name
147 class CmdlineCheck(OptCheck):
154 def __init__(self, ver_expected):
155 self.ver_expected = ver_expected
164 if self.ver[0] > self.ver_expected[0]:
165 self.result = 'OK: version >= ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
167 if self.ver[0] < self.ver_expected[0]:
168 self.result = 'FAIL: version < ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
170 if self.ver[1] >= self.ver_expected[1]:
171 self.result = 'OK: version >= ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
173 self.result = 'FAIL: version < ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
175 def table_print(self, _mode, with_results):
176 ver_req = 'kernel version >= ' + str(self.ver_expected[0]) + '.' + str(self.ver_expected[1])
177 print('{:<91}'.format(ver_req), end='')
179 print('| {}'.format(self.result), end='')
182 class ComplexOptCheck:
183 def __init__(self, *opts):
186 'empty {} check'.format(self.__class__.__name__)
187 assert(len(self.opts) != 1), \
188 'useless {} check: {}'.format(self.__class__.__name__, opts)
189 assert(isinstance(opts[0], (KconfigCheck, CmdlineCheck))), \
190 'invalid {} check: {}'.format(self.__class__.__name__, opts)
199 return self.opts[0].name
203 return self.opts[0].expected
205 def table_print(self, mode, with_results):
206 if mode == 'verbose':
207 print(' {:87}'.format('<<< ' + self.__class__.__name__ + ' >>>'), end='')
209 print('| {}'.format(self.result), end='')
212 o.table_print(mode, with_results)
215 o.table_print(mode, False)
217 print('| {}'.format(self.result), end='')
219 def json_dump(self, with_results):
220 dump = self.opts[0].json_dump(False)
222 dump.append(self.result)
226 class OR(ComplexOptCheck):
227 # self.opts[0] is the option that this OR-check is about.
229 # OR(<X_is_hardened>, <X_is_disabled>)
230 # OR(<X_is_hardened>, <old_X_is_hardened>)
232 for i, opt in enumerate(self.opts):
234 if opt.result.startswith('OK'):
235 self.result = opt.result
236 # Add more info for additional checks:
238 if opt.result == 'OK':
239 self.result = 'OK: {} "{}"'.format(opt.name, opt.expected)
240 elif opt.result == 'OK: not found':
241 self.result = 'OK: {} not found'.format(opt.name)
242 elif opt.result == 'OK: is present':
243 self.result = 'OK: {} is present'.format(opt.name)
245 # VersionCheck provides enough info
246 assert(opt.result.startswith('OK: version')), \
247 'unexpected OK description "{}"'.format(opt.result)
249 self.result = self.opts[0].result
252 class AND(ComplexOptCheck):
253 # self.opts[0] is the option that this AND-check is about.
255 # AND(<suboption>, <main_option>)
256 # Suboption is not checked if checking of the main_option is failed.
257 # AND(<X_is_disabled>, <old_X_is_disabled>)
259 for i, opt in reversed(list(enumerate(self.opts))):
262 self.result = opt.result
264 if not opt.result.startswith('OK'):
265 # This FAIL is caused by additional checks,
266 # and not by the main option that this AND-check is about.
267 # Describe the reason of the FAIL.
268 if opt.result.startswith('FAIL: \"') or opt.result == 'FAIL: not found':
269 self.result = 'FAIL: {} not "{}"'.format(opt.name, opt.expected)
270 elif opt.result == 'FAIL: not present':
271 self.result = 'FAIL: {} not present'.format(opt.name)
273 # VersionCheck provides enough info
274 self.result = opt.result
275 assert(opt.result.startswith('FAIL: version')), \
276 'unexpected FAIL description "{}"'.format(opt.result)
280 def detect_arch(fname, archs):
281 with open(fname, 'r') as f:
282 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
284 for line in f.readlines():
285 if arch_pattern.match(line):
286 option, _ = line[7:].split('=', 1)
291 return None, 'more than one supported architecture is detected'
293 return None, 'failed to detect architecture'
297 def detect_version(fname):
298 with open(fname, 'r') as f:
299 ver_pattern = re.compile("# Linux/.* Kernel Configuration")
300 for line in f.readlines():
301 if ver_pattern.match(line):
305 ver_numbers = ver_str.split('.')
306 if len(ver_numbers) < 3 or not ver_numbers[0].isdigit() or not ver_numbers[1].isdigit():
307 msg = 'failed to parse the version "' + ver_str + '"'
309 return (int(ver_numbers[0]), int(ver_numbers[1])), None
310 return None, 'no kernel version detected'
313 def add_kconfig_checks(l, arch):
314 # Calling the KconfigCheck class constructor:
315 # KconfigCheck(reason, decision, name, expected)
317 modules_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'MODULES', 'is not set')
318 devmem_not_set = KconfigCheck('cut_attack_surface', 'kspp', 'DEVMEM', 'is not set') # refers to LOCKDOWN
319 bpf_syscall_not_set = KconfigCheck('cut_attack_surface', 'lockdown', 'BPF_SYSCALL', 'is not set') # refers to LOCKDOWN
320 efi_not_set = KconfigCheck('cut_attack_surface', 'my', 'EFI', 'is not set')
322 # 'self_protection', 'defconfig'
323 l += [KconfigCheck('self_protection', 'defconfig', 'BUG', 'y')]
324 l += [KconfigCheck('self_protection', 'defconfig', 'SLUB_DEBUG', 'y')]
325 l += [KconfigCheck('self_protection', 'defconfig', 'GCC_PLUGINS', 'y')]
326 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR', 'y'),
327 KconfigCheck('self_protection', 'defconfig', 'CC_STACKPROTECTOR', 'y'))]
328 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR_STRONG', 'y'),
329 KconfigCheck('self_protection', 'defconfig', 'CC_STACKPROTECTOR_STRONG', 'y'))]
330 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STRICT_KERNEL_RWX', 'y'),
331 KconfigCheck('self_protection', 'defconfig', 'DEBUG_RODATA', 'y'))] # before v4.11
332 l += [OR(KconfigCheck('self_protection', 'defconfig', 'STRICT_MODULE_RWX', 'y'),
333 KconfigCheck('self_protection', 'defconfig', 'DEBUG_SET_MODULE_RONX', 'y'),
334 modules_not_set)] # DEBUG_SET_MODULE_RONX was before v4.11
335 l += [OR(KconfigCheck('self_protection', 'defconfig', 'REFCOUNT_FULL', 'y'),
336 VersionCheck((5, 5)))] # REFCOUNT_FULL is enabled by default since v5.5
337 l += [KconfigCheck('self_protection', 'defconfig', 'THREAD_INFO_IN_TASK', 'y')]
338 iommu_support_is_set = KconfigCheck('self_protection', 'defconfig', 'IOMMU_SUPPORT', 'y')
339 l += [iommu_support_is_set] # is needed for mitigating DMA attacks
340 if arch in ('X86_64', 'ARM64', 'X86_32'):
341 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_BASE', 'y')]
342 if arch in ('X86_64', 'ARM64'):
343 l += [KconfigCheck('self_protection', 'defconfig', 'VMAP_STACK', 'y')]
344 if arch in ('X86_64', 'X86_32'):
345 l += [KconfigCheck('self_protection', 'defconfig', 'MICROCODE', 'y')] # is needed for mitigating CPU bugs
346 l += [KconfigCheck('self_protection', 'defconfig', 'RETPOLINE', 'y')]
347 l += [KconfigCheck('self_protection', 'defconfig', 'X86_SMAP', 'y')]
348 l += [KconfigCheck('self_protection', 'defconfig', 'SYN_COOKIES', 'y')] # another reason?
349 l += [OR(KconfigCheck('self_protection', 'defconfig', 'X86_UMIP', 'y'),
350 KconfigCheck('self_protection', 'defconfig', 'X86_INTEL_UMIP', 'y'))]
351 if arch in ('ARM64', 'ARM'):
352 l += [KconfigCheck('self_protection', 'defconfig', 'STACKPROTECTOR_PER_TASK', 'y')]
354 l += [KconfigCheck('self_protection', 'defconfig', 'PAGE_TABLE_ISOLATION', 'y')]
355 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_MEMORY', 'y')]
356 l += [AND(KconfigCheck('self_protection', 'defconfig', 'INTEL_IOMMU', 'y'),
357 iommu_support_is_set)]
358 l += [AND(KconfigCheck('self_protection', 'defconfig', 'AMD_IOMMU', 'y'),
359 iommu_support_is_set)]
361 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_PAN', 'y')]
362 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_EPAN', 'y')]
363 l += [KconfigCheck('self_protection', 'defconfig', 'UNMAP_KERNEL_AT_EL0', 'y')]
364 l += [OR(KconfigCheck('self_protection', 'defconfig', 'HARDEN_EL2_VECTORS', 'y'),
365 AND(KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_BASE', 'y'),
366 VersionCheck((5, 9))))] # HARDEN_EL2_VECTORS was included in RANDOMIZE_BASE in v5.9
367 l += [KconfigCheck('self_protection', 'defconfig', 'RODATA_FULL_DEFAULT_ENABLED', 'y')]
368 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_PTR_AUTH_KERNEL', 'y')]
369 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_BTI_KERNEL', 'y')]
370 l += [OR(KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_PREDICTOR', 'y'),
371 VersionCheck((5, 10)))] # HARDEN_BRANCH_PREDICTOR is enabled by default since v5.10
372 l += [KconfigCheck('self_protection', 'defconfig', 'MITIGATE_SPECTRE_BRANCH_HISTORY', 'y')]
373 l += [KconfigCheck('self_protection', 'defconfig', 'ARM64_MTE', 'y')]
374 l += [KconfigCheck('self_protection', 'defconfig', 'RANDOMIZE_MODULE_REGION_FULL', 'y')]
376 l += [KconfigCheck('self_protection', 'defconfig', 'CPU_SW_DOMAIN_PAN', 'y')]
377 l += [KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_PREDICTOR', 'y')]
378 l += [KconfigCheck('self_protection', 'defconfig', 'HARDEN_BRANCH_HISTORY', 'y')]
380 # 'self_protection', 'kspp'
381 l += [KconfigCheck('self_protection', 'kspp', 'SECURITY_DMESG_RESTRICT', 'y')]
382 l += [KconfigCheck('self_protection', 'kspp', 'BUG_ON_DATA_CORRUPTION', 'y')]
383 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_WX', 'y')]
384 l += [KconfigCheck('self_protection', 'kspp', 'SCHED_STACK_END_CHECK', 'y')]
385 l += [KconfigCheck('self_protection', 'kspp', 'SLAB_FREELIST_HARDENED', 'y')]
386 l += [KconfigCheck('self_protection', 'kspp', 'SLAB_FREELIST_RANDOM', 'y')]
387 l += [KconfigCheck('self_protection', 'kspp', 'SHUFFLE_PAGE_ALLOCATOR', 'y')]
388 l += [KconfigCheck('self_protection', 'kspp', 'FORTIFY_SOURCE', 'y')]
389 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_LIST', 'y')]
390 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_SG', 'y')]
391 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_CREDENTIALS', 'y')]
392 l += [KconfigCheck('self_protection', 'kspp', 'DEBUG_NOTIFIERS', 'y')]
393 l += [KconfigCheck('self_protection', 'kspp', 'INIT_ON_ALLOC_DEFAULT_ON', 'y')]
394 l += [KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_LATENT_ENTROPY', 'y')]
395 l += [KconfigCheck('self_protection', 'kspp', 'KFENCE', 'y')]
396 l += [KconfigCheck('self_protection', 'kspp', 'WERROR', 'y')]
397 l += [KconfigCheck('self_protection', 'kspp', 'IOMMU_DEFAULT_DMA_STRICT', 'y')]
398 l += [KconfigCheck('self_protection', 'kspp', 'ZERO_CALL_USED_REGS', 'y')]
399 randstruct_is_set = KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_RANDSTRUCT', 'y')
400 l += [randstruct_is_set]
401 hardened_usercopy_is_set = KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY', 'y')
402 l += [hardened_usercopy_is_set]
403 l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_FALLBACK', 'is not set'),
404 hardened_usercopy_is_set)]
405 l += [AND(KconfigCheck('self_protection', 'kspp', 'HARDENED_USERCOPY_PAGESPAN', 'is not set'),
406 hardened_usercopy_is_set)]
407 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG', 'y'),
409 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_ALL', 'y'),
411 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_SHA512', 'y'),
413 l += [OR(KconfigCheck('self_protection', 'kspp', 'MODULE_SIG_FORCE', 'y'),
414 modules_not_set)] # refers to LOCKDOWN
415 l += [OR(KconfigCheck('self_protection', 'kspp', 'INIT_STACK_ALL_ZERO', 'y'),
416 KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_STRUCTLEAK_BYREF_ALL', 'y'))]
417 l += [OR(KconfigCheck('self_protection', 'kspp', 'INIT_ON_FREE_DEFAULT_ON', 'y'),
418 KconfigCheck('self_protection', 'kspp', 'PAGE_POISONING_ZERO', 'y'))]
419 # CONFIG_INIT_ON_FREE_DEFAULT_ON was added in v5.3.
420 # CONFIG_PAGE_POISONING_ZERO was removed in v5.11.
421 # Starting from v5.11 CONFIG_PAGE_POISONING unconditionally checks
422 # the 0xAA poison pattern on allocation.
423 # That brings higher performance penalty.
424 if arch in ('X86_64', 'ARM64', 'X86_32'):
425 stackleak_is_set = KconfigCheck('self_protection', 'kspp', 'GCC_PLUGIN_STACKLEAK', 'y')
426 l += [stackleak_is_set]
427 l += [KconfigCheck('self_protection', 'kspp', 'RANDOMIZE_KSTACK_OFFSET_DEFAULT', 'y')]
428 if arch in ('X86_64', 'X86_32'):
429 l += [KconfigCheck('self_protection', 'kspp', 'SCHED_CORE', 'y')]
430 l += [KconfigCheck('self_protection', 'kspp', 'DEFAULT_MMAP_MIN_ADDR', '65536')]
431 if arch in ('ARM64', 'ARM'):
432 l += [KconfigCheck('self_protection', 'kspp', 'DEFAULT_MMAP_MIN_ADDR', '32768')]
433 l += [KconfigCheck('self_protection', 'kspp', 'SYN_COOKIES', 'y')] # another reason?
435 l += [KconfigCheck('self_protection', 'kspp', 'ARM64_SW_TTBR0_PAN', 'y')]
437 l += [KconfigCheck('self_protection', 'kspp', 'PAGE_TABLE_ISOLATION', 'y')]
438 l += [KconfigCheck('self_protection', 'kspp', 'HIGHMEM64G', 'y')]
439 l += [KconfigCheck('self_protection', 'kspp', 'X86_PAE', 'y')]
441 # 'self_protection', 'maintainer'
442 ubsan_bounds_is_set = KconfigCheck('self_protection', 'maintainer', 'UBSAN_BOUNDS', 'y') # only array index bounds checking
443 l += [ubsan_bounds_is_set] # recommended by Kees Cook in /issues/53
444 if arch in ('X86_64', 'ARM64', 'X86_32'): # ARCH_HAS_UBSAN_SANITIZE_ALL is not enabled for ARM
445 l += [AND(KconfigCheck('self_protection', 'maintainer', 'UBSAN_SANITIZE_ALL', 'y'),
446 ubsan_bounds_is_set)] # recommended by Kees Cook in /issues/53
447 l += [AND(KconfigCheck('self_protection', 'maintainer', 'UBSAN_TRAP', 'y'),
448 ubsan_bounds_is_set)] # recommended by Kees Cook in /issues/53
450 # 'self_protection', 'clipos'
451 l += [KconfigCheck('self_protection', 'clipos', 'DEBUG_VIRTUAL', 'y')]
452 l += [KconfigCheck('self_protection', 'clipos', 'STATIC_USERMODEHELPER', 'y')] # needs userspace support
453 l += [OR(KconfigCheck('self_protection', 'clipos', 'EFI_DISABLE_PCI_DMA', 'y'),
455 l += [KconfigCheck('self_protection', 'clipos', 'SLAB_MERGE_DEFAULT', 'is not set')]
456 l += [KconfigCheck('self_protection', 'clipos', 'RANDOM_TRUST_BOOTLOADER', 'is not set')]
457 l += [KconfigCheck('self_protection', 'clipos', 'RANDOM_TRUST_CPU', 'is not set')]
458 l += [AND(KconfigCheck('self_protection', 'clipos', 'GCC_PLUGIN_RANDSTRUCT_PERFORMANCE', 'is not set'),
460 if arch in ('X86_64', 'ARM64', 'X86_32'):
461 l += [AND(KconfigCheck('self_protection', 'clipos', 'STACKLEAK_METRICS', 'is not set'),
463 l += [AND(KconfigCheck('self_protection', 'clipos', 'STACKLEAK_RUNTIME_DISABLE', 'is not set'),
465 if arch in ('X86_64', 'X86_32'):
466 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU_DEFAULT_ON', 'y'),
467 iommu_support_is_set)]
469 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU_SVM', 'y'),
470 iommu_support_is_set)]
472 l += [AND(KconfigCheck('self_protection', 'clipos', 'INTEL_IOMMU', 'y'),
473 iommu_support_is_set)]
475 # 'self_protection', 'my'
476 l += [OR(KconfigCheck('self_protection', 'my', 'RESET_ATTACK_MITIGATION', 'y'),
477 efi_not_set)] # needs userspace support (systemd)
479 l += [KconfigCheck('self_protection', 'my', 'SLS', 'y')] # vs CVE-2021-26341 in Straight-Line-Speculation
480 l += [AND(KconfigCheck('self_protection', 'my', 'AMD_IOMMU_V2', 'y'),
481 iommu_support_is_set)]
483 l += [KconfigCheck('self_protection', 'my', 'SHADOW_CALL_STACK', 'y')] # depends on clang, maybe it's alternative to STACKPROTECTOR_STRONG
484 l += [KconfigCheck('self_protection', 'my', 'KASAN_HW_TAGS', 'y')]
485 cfi_clang_is_set = KconfigCheck('self_protection', 'my', 'CFI_CLANG', 'y')
486 l += [cfi_clang_is_set]
487 l += [AND(KconfigCheck('self_protection', 'my', 'CFI_PERMISSIVE', 'is not set'),
491 if arch in ('X86_64', 'ARM64', 'X86_32'):
492 l += [KconfigCheck('security_policy', 'defconfig', 'SECURITY', 'y')] # and choose your favourite LSM
494 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY', 'y')] # and choose your favourite LSM
495 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY_YAMA', 'y')]
496 l += [KconfigCheck('security_policy', 'kspp', 'SECURITY_SELINUX_DISABLE', 'is not set')]
497 l += [KconfigCheck('security_policy', 'clipos', 'SECURITY_LOCKDOWN_LSM', 'y')]
498 l += [KconfigCheck('security_policy', 'clipos', 'SECURITY_LOCKDOWN_LSM_EARLY', 'y')]
499 l += [KconfigCheck('security_policy', 'clipos', 'LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY', 'y')]
500 l += [KconfigCheck('security_policy', 'my', 'SECURITY_WRITABLE_HOOKS', 'is not set')] # refers to SECURITY_SELINUX_DISABLE
501 l += [KconfigCheck('security_policy', 'my', 'SECURITY_SAFESETID', 'y')]
502 loadpin_is_set = KconfigCheck('security_policy', 'my', 'SECURITY_LOADPIN', 'y')
503 l += [loadpin_is_set] # needs userspace support
504 l += [AND(KconfigCheck('security_policy', 'my', 'SECURITY_LOADPIN_ENFORCE', 'y'),
507 # 'cut_attack_surface', 'defconfig'
508 l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'BPF_UNPRIV_DEFAULT_OFF', 'y'),
509 bpf_syscall_not_set)] # see unprivileged_bpf_disabled
510 l += [KconfigCheck('cut_attack_surface', 'defconfig', 'SECCOMP', 'y')]
511 l += [KconfigCheck('cut_attack_surface', 'defconfig', 'SECCOMP_FILTER', 'y')]
512 if arch in ('X86_64', 'ARM64', 'X86_32'):
513 l += [OR(KconfigCheck('cut_attack_surface', 'defconfig', 'STRICT_DEVMEM', 'y'),
514 devmem_not_set)] # refers to LOCKDOWN
516 # 'cut_attack_surface', 'kspp'
517 l += [KconfigCheck('cut_attack_surface', 'kspp', 'ACPI_CUSTOM_METHOD', 'is not set')] # refers to LOCKDOWN
518 l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_BRK', 'is not set')]
519 l += [KconfigCheck('cut_attack_surface', 'kspp', 'DEVKMEM', 'is not set')] # refers to LOCKDOWN
520 l += [KconfigCheck('cut_attack_surface', 'kspp', 'COMPAT_VDSO', 'is not set')]
521 l += [KconfigCheck('cut_attack_surface', 'kspp', 'BINFMT_MISC', 'is not set')]
522 l += [KconfigCheck('cut_attack_surface', 'kspp', 'INET_DIAG', 'is not set')]
523 l += [KconfigCheck('cut_attack_surface', 'kspp', 'KEXEC', 'is not set')] # refers to LOCKDOWN
524 l += [KconfigCheck('cut_attack_surface', 'kspp', 'PROC_KCORE', 'is not set')] # refers to LOCKDOWN
525 l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_PTYS', 'is not set')]
526 l += [KconfigCheck('cut_attack_surface', 'kspp', 'HIBERNATION', 'is not set')] # refers to LOCKDOWN
527 l += [KconfigCheck('cut_attack_surface', 'kspp', 'IA32_EMULATION', 'is not set')]
528 l += [KconfigCheck('cut_attack_surface', 'kspp', 'X86_X32', 'is not set')]
529 l += [KconfigCheck('cut_attack_surface', 'kspp', 'MODIFY_LDT_SYSCALL', 'is not set')]
530 l += [KconfigCheck('cut_attack_surface', 'kspp', 'OABI_COMPAT', 'is not set')]
531 l += [KconfigCheck('cut_attack_surface', 'kspp', 'X86_MSR', 'is not set')] # refers to LOCKDOWN
532 l += [modules_not_set]
533 l += [devmem_not_set]
534 l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'IO_STRICT_DEVMEM', 'y'),
535 devmem_not_set)] # refers to LOCKDOWN
537 l += [OR(KconfigCheck('cut_attack_surface', 'kspp', 'STRICT_DEVMEM', 'y'),
538 devmem_not_set)] # refers to LOCKDOWN
540 l += [KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_VSYSCALL_NONE', 'y')] # 'vsyscall=none'
542 # 'cut_attack_surface', 'grsec'
543 l += [KconfigCheck('cut_attack_surface', 'grsec', 'ZSMALLOC_STAT', 'is not set')]
544 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PAGE_OWNER', 'is not set')]
545 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEBUG_KMEMLEAK', 'is not set')]
546 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BINFMT_AOUT', 'is not set')]
547 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KPROBE_EVENTS', 'is not set')]
548 l += [KconfigCheck('cut_attack_surface', 'grsec', 'UPROBE_EVENTS', 'is not set')]
549 l += [KconfigCheck('cut_attack_surface', 'grsec', 'GENERIC_TRACER', 'is not set')] # refers to LOCKDOWN
550 l += [KconfigCheck('cut_attack_surface', 'grsec', 'FUNCTION_TRACER', 'is not set')]
551 l += [KconfigCheck('cut_attack_surface', 'grsec', 'STACK_TRACER', 'is not set')]
552 l += [KconfigCheck('cut_attack_surface', 'grsec', 'HIST_TRIGGERS', 'is not set')]
553 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BLK_DEV_IO_TRACE', 'is not set')]
554 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROC_VMCORE', 'is not set')]
555 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROC_PAGE_MONITOR', 'is not set')]
556 l += [KconfigCheck('cut_attack_surface', 'grsec', 'USELIB', 'is not set')]
557 l += [KconfigCheck('cut_attack_surface', 'grsec', 'CHECKPOINT_RESTORE', 'is not set')]
558 l += [KconfigCheck('cut_attack_surface', 'grsec', 'USERFAULTFD', 'is not set')]
559 l += [KconfigCheck('cut_attack_surface', 'grsec', 'HWPOISON_INJECT', 'is not set')]
560 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MEM_SOFT_DIRTY', 'is not set')]
561 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEVPORT', 'is not set')] # refers to LOCKDOWN
562 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DEBUG_FS', 'is not set')] # refers to LOCKDOWN
563 l += [KconfigCheck('cut_attack_surface', 'grsec', 'NOTIFIER_ERROR_INJECTION', 'is not set')]
564 l += [KconfigCheck('cut_attack_surface', 'grsec', 'FAIL_FUTEX', 'is not set')]
565 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PUNIT_ATOM_DEBUG', 'is not set')]
566 l += [KconfigCheck('cut_attack_surface', 'grsec', 'ACPI_CONFIGFS', 'is not set')]
567 l += [KconfigCheck('cut_attack_surface', 'grsec', 'EDAC_DEBUG', 'is not set')]
568 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DRM_I915_DEBUG', 'is not set')]
569 l += [KconfigCheck('cut_attack_surface', 'grsec', 'BCACHE_CLOSURES_DEBUG', 'is not set')]
570 l += [KconfigCheck('cut_attack_surface', 'grsec', 'DVB_C8SECTPFE', 'is not set')]
571 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MTD_SLRAM', 'is not set')]
572 l += [KconfigCheck('cut_attack_surface', 'grsec', 'MTD_PHRAM', 'is not set')]
573 l += [KconfigCheck('cut_attack_surface', 'grsec', 'IO_URING', 'is not set')]
574 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KCMP', 'is not set')]
575 l += [KconfigCheck('cut_attack_surface', 'grsec', 'RSEQ', 'is not set')]
576 l += [KconfigCheck('cut_attack_surface', 'grsec', 'LATENCYTOP', 'is not set')]
577 l += [KconfigCheck('cut_attack_surface', 'grsec', 'KCOV', 'is not set')]
578 l += [KconfigCheck('cut_attack_surface', 'grsec', 'PROVIDE_OHCI1394_DMA_INIT', 'is not set')]
579 l += [KconfigCheck('cut_attack_surface', 'grsec', 'SUNRPC_DEBUG', 'is not set')]
580 l += [AND(KconfigCheck('cut_attack_surface', 'grsec', 'PTDUMP_DEBUGFS', 'is not set'),
581 KconfigCheck('cut_attack_surface', 'grsec', 'X86_PTDUMP', 'is not set'))]
583 # 'cut_attack_surface', 'maintainer'
584 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'DRM_LEGACY', 'is not set')] # recommended by Daniel Vetter in /issues/38
585 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'FB', 'is not set')] # recommended by Daniel Vetter in /issues/38
586 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'VT', 'is not set')] # recommended by Daniel Vetter in /issues/38
587 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'BLK_DEV_FD', 'is not set')] # recommended by Denis Efremov in /pull/54
588 l += [KconfigCheck('cut_attack_surface', 'maintainer', 'BLK_DEV_FD_RAWCMD', 'is not set')] # recommended by Denis Efremov in /pull/62
590 # 'cut_attack_surface', 'grapheneos'
591 l += [KconfigCheck('cut_attack_surface', 'grapheneos', 'AIO', 'is not set')]
593 # 'cut_attack_surface', 'clipos'
594 l += [KconfigCheck('cut_attack_surface', 'clipos', 'STAGING', 'is not set')]
595 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KSM', 'is not set')] # to prevent FLUSH+RELOAD attack
596 # l += [KconfigCheck('cut_attack_surface', 'clipos', 'IKCONFIG', 'is not set')] # no, IKCONFIG is needed for this check :)
597 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KALLSYMS', 'is not set')]
598 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_VSYSCALL_EMULATION', 'is not set')]
599 l += [KconfigCheck('cut_attack_surface', 'clipos', 'MAGIC_SYSRQ', 'is not set')]
600 l += [KconfigCheck('cut_attack_surface', 'clipos', 'KEXEC_FILE', 'is not set')] # refers to LOCKDOWN (permissive)
601 l += [KconfigCheck('cut_attack_surface', 'clipos', 'USER_NS', 'is not set')] # user.max_user_namespaces=0
602 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_CPUID', 'is not set')]
603 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_IOPL_IOPERM', 'is not set')] # refers to LOCKDOWN
604 l += [KconfigCheck('cut_attack_surface', 'clipos', 'ACPI_TABLE_UPGRADE', 'is not set')] # refers to LOCKDOWN
605 l += [KconfigCheck('cut_attack_surface', 'clipos', 'EFI_CUSTOM_SSDT_OVERLAYS', 'is not set')]
606 l += [AND(KconfigCheck('cut_attack_surface', 'clipos', 'LDISC_AUTOLOAD', 'is not set'),
607 KconfigCheck('cut_attack_surface', 'clipos', 'LDISC_AUTOLOAD'))] # option presence check
608 if arch in ('X86_64', 'X86_32'):
609 l += [KconfigCheck('cut_attack_surface', 'clipos', 'X86_INTEL_TSX_MODE_OFF', 'y')] # tsx=off
611 # 'cut_attack_surface', 'lockdown'
612 l += [bpf_syscall_not_set] # refers to LOCKDOWN
613 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'EFI_TEST', 'is not set')] # refers to LOCKDOWN
614 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'MMIOTRACE_TEST', 'is not set')] # refers to LOCKDOWN
615 l += [KconfigCheck('cut_attack_surface', 'lockdown', 'KPROBES', 'is not set')] # refers to LOCKDOWN
617 # 'cut_attack_surface', 'my'
618 l += [OR(KconfigCheck('cut_attack_surface', 'my', 'TRIM_UNUSED_KSYMS', 'y'),
620 l += [KconfigCheck('cut_attack_surface', 'my', 'MMIOTRACE', 'is not set')] # refers to LOCKDOWN (permissive)
621 l += [KconfigCheck('cut_attack_surface', 'my', 'LIVEPATCH', 'is not set')]
622 l += [KconfigCheck('cut_attack_surface', 'my', 'IP_DCCP', 'is not set')]
623 l += [KconfigCheck('cut_attack_surface', 'my', 'IP_SCTP', 'is not set')]
624 l += [KconfigCheck('cut_attack_surface', 'my', 'FTRACE', 'is not set')] # refers to LOCKDOWN
625 l += [KconfigCheck('cut_attack_surface', 'my', 'VIDEO_VIVID', 'is not set')]
626 l += [KconfigCheck('cut_attack_surface', 'my', 'INPUT_EVBUG', 'is not set')] # Can be used as a keylogger
627 l += [KconfigCheck('cut_attack_surface', 'my', 'KGDB', 'is not set')]
630 if arch in ('X86_64', 'ARM64', 'X86_32'):
631 l += [KconfigCheck('harden_userspace', 'defconfig', 'INTEGRITY', 'y')]
633 l += [KconfigCheck('harden_userspace', 'my', 'INTEGRITY', 'y')]
634 if arch in ('ARM', 'X86_32'):
635 l += [KconfigCheck('harden_userspace', 'defconfig', 'VMSPLIT_3G', 'y')]
636 if arch in ('X86_64', 'ARM64'):
637 l += [KconfigCheck('harden_userspace', 'clipos', 'ARCH_MMAP_RND_BITS', '32')]
638 if arch in ('X86_32', 'ARM'):
639 l += [KconfigCheck('harden_userspace', 'my', 'ARCH_MMAP_RND_BITS', '16')]
641 # l += [KconfigCheck('feature_test', 'my', 'LKDTM', 'm')] # only for debugging!
644 def add_cmdline_checks(l, arch):
645 # Calling the CmdlineCheck class constructor:
646 # CmdlineCheck(reason, decision, name, expected)
647 # Don't add CmdlineChecks in add_kconfig_checks() to avoid wrong results
648 # when the tool doesn't check the cmdline.
650 l += [OR(CmdlineCheck('self_protection', 'kspp', 'init_on_alloc', '1'),
651 AND(KconfigCheck('self_protection', 'kspp', 'INIT_ON_ALLOC_DEFAULT_ON', 'y'),
652 CmdlineCheck('self_protection', 'kspp', 'init_on_alloc', 'is not set')))]
653 l += [OR(CmdlineCheck('self_protection', 'kspp', 'init_on_free', '1'),
654 AND(KconfigCheck('self_protection', 'kspp', 'INIT_ON_FREE_DEFAULT_ON', 'y'),
655 CmdlineCheck('self_protection', 'kspp', 'init_on_free', 'is not set')),
656 AND(CmdlineCheck('self_protection', 'kspp', 'page_poison', '1'),
657 KconfigCheck('self_protection', 'kspp', 'PAGE_POISONING_ZERO', 'y'),
658 CmdlineCheck('self_protection', 'kspp', 'slub_debug', 'P')))]
659 l += [OR(CmdlineCheck('self_protection', 'kspp', 'slab_nomerge'),
660 AND(KconfigCheck('self_protection', 'clipos', 'SLAB_MERGE_DEFAULT', 'is not set'),
661 CmdlineCheck('self_protection', 'kspp', 'slab_merge', 'is not set')))] # option presence check
662 if arch in ('X86_64', 'ARM64', 'X86_32'):
663 l += [OR(CmdlineCheck('self_protection', 'kspp', 'randomize_kstack_offset', '1'),
664 AND(KconfigCheck('self_protection', 'kspp', 'RANDOMIZE_KSTACK_OFFSET_DEFAULT', 'y'),
665 CmdlineCheck('self_protection', 'kspp', 'randomize_kstack_offset', 'is not set')))]
666 if arch in ('X86_64', 'X86_32'):
667 l += [CmdlineCheck('self_protection', 'kspp', 'pti', 'on')]
670 l += [OR(CmdlineCheck('cut_attack_surface', 'kspp', 'vsyscall', 'none'),
671 AND(KconfigCheck('cut_attack_surface', 'kspp', 'LEGACY_VSYSCALL_NONE', 'y'),
672 CmdlineCheck('cut_attack_surface', 'kspp', 'vsyscall', 'is not set')))]
677 def print_unknown_options(checklist, parsed_options):
681 if o1.type != 'complex':
682 known_options.append(o1.name)
685 if o2.type != 'complex':
686 if hasattr(o2, 'name'):
687 known_options.append(o2.name)
690 assert(o3.type != 'complex'), \
691 'unexpected ComplexOptCheck inside {}'.format(o2.name)
692 if hasattr(o3, 'name'):
693 known_options.append(o3.name)
695 for option, value in parsed_options.items():
696 if option not in known_options:
697 print('[?] No check for option {} ({})'.format(option, value))
700 def print_checklist(mode, checklist, with_results):
704 output.append(o.json_dump(with_results))
705 print(json.dumps(output))
712 print('=' * sep_line_len)
713 print('{:^40}|{:^7}|{:^12}|{:^10}|{:^18}'.format('option name', 'type', 'desired val', 'decision', 'reason'), end='')
715 print('| {}'.format('check result'), end='')
717 print('=' * sep_line_len)
720 for opt in checklist:
722 if mode == 'show_ok':
723 if not opt.result.startswith('OK'):
725 if mode == 'show_fail':
726 if not opt.result.startswith('FAIL'):
728 opt.table_print(mode, with_results)
730 if mode == 'verbose':
731 print('-' * sep_line_len)
736 fail_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
738 ok_count = len(list(filter(lambda opt: opt.result.startswith('OK'), checklist)))
740 if mode == 'show_ok':
741 fail_suppressed = ' (suppressed in output)'
742 if mode == 'show_fail':
743 ok_suppressed = ' (suppressed in output)'
745 print('[+] Config check is finished: \'OK\' - {}{} / \'FAIL\' - {}{}'.format(ok_count, ok_suppressed, fail_count, fail_suppressed))
748 def populate_simple_opt_with_data(opt, data, data_type):
749 assert(opt.type != 'complex'), \
750 'unexpected ComplexOptCheck "{}"'.format(opt.name)
751 assert(opt.type in SIMPLE_OPTION_TYPES), \
752 'invalid opt type "{}"'.format(opt.type)
753 assert(data_type in SIMPLE_OPTION_TYPES), \
754 'invalid data type "{}"'.format(data_type)
756 if data_type != opt.type:
759 if data_type in ('kconfig', 'cmdline'):
760 opt.state = data.get(opt.name, None)
762 assert(data_type == 'version'), \
763 'unexpected data type "{}"'.format(data_type)
767 def populate_opt_with_data(opt, data, data_type):
768 if opt.type == 'complex':
770 if o.type == 'complex':
771 # Recursion for nested ComplexOptCheck objects
772 populate_opt_with_data(o, data, data_type)
774 populate_simple_opt_with_data(o, data, data_type)
776 assert(opt.type in ('kconfig', 'cmdline')), \
777 'bad type "{}" for a simple check'.format(opt.type)
778 populate_simple_opt_with_data(opt, data, data_type)
781 def populate_with_data(checklist, data, data_type):
782 for opt in checklist:
783 populate_opt_with_data(opt, data, data_type)
786 def perform_checks(checklist):
787 for opt in checklist:
791 def parse_kconfig_file(parsed_options, fname):
792 with open(fname, 'r') as f:
793 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
794 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
796 for line in f.readlines():
801 if opt_is_on.match(line):
802 option, value = line.split('=', 1)
803 if value == 'is not set':
804 sys.exit('[!] ERROR: bad enabled kconfig option "{}"'.format(line))
805 elif opt_is_off.match(line):
806 option, value = line[2:].split(' ', 1)
807 if value != 'is not set':
808 sys.exit('[!] ERROR: bad disabled kconfig option "{}"'.format(line))
810 if option in parsed_options:
811 sys.exit('[!] ERROR: kconfig option "{}" exists multiple times'.format(line))
814 parsed_options[option] = value
817 def parse_cmdline_file(parsed_options, fname):
818 with open(fname, 'r') as f:
824 sys.exit('[!] ERROR: more than one line in "{}"'.format(fname))
828 name, value = opt.split('=', 1)
831 value = '' # '' is not None
832 parsed_options[name] = value
838 # - reporting about unknown kernel options in the kconfig
839 # - verbose printing of ComplexOptCheck items
840 # * json mode for printing the results in JSON format
841 report_modes = ['verbose', 'json', 'show_ok', 'show_fail']
842 supported_archs = ['X86_64', 'X86_32', 'ARM64', 'ARM']
843 parser = ArgumentParser(prog='kconfig-hardened-check',
844 description='A tool for checking the security hardening options of the Linux kernel')
845 parser.add_argument('--version', action='version', version='%(prog)s ' + __version__)
846 parser.add_argument('-p', '--print', choices=supported_archs,
847 help='print security hardening preferences for the selected architecture')
848 parser.add_argument('-c', '--config',
849 help='check the kernel kconfig file against these preferences')
850 parser.add_argument('-l', '--cmdline',
851 help='check the kernel cmdline file against these preferences')
852 parser.add_argument('-m', '--mode', choices=report_modes,
853 help='choose the report mode')
854 args = parser.parse_args()
860 print('[+] Special report mode: {}'.format(mode))
862 config_checklist = []
866 sys.exit('[!] ERROR: --config and --print can\'t be used together')
869 print('[+] Kconfig file to check: {}'.format(args.config))
871 print('[+] Kernel cmdline file to check: {}'.format(args.cmdline))
873 arch, msg = detect_arch(args.config, supported_archs)
875 sys.exit('[!] ERROR: {}'.format(msg))
877 print('[+] Detected architecture: {}'.format(arch))
879 kernel_version, msg = detect_version(args.config)
880 if not kernel_version:
881 sys.exit('[!] ERROR: {}'.format(msg))
883 print('[+] Detected kernel version: {}.{}'.format(kernel_version[0], kernel_version[1]))
885 # add relevant kconfig checks to the checklist
886 add_kconfig_checks(config_checklist, arch)
889 # add relevant cmdline checks to the checklist
890 add_cmdline_checks(config_checklist, arch)
892 # populate the checklist with the parsed kconfig data
893 parsed_kconfig_options = OrderedDict()
894 parse_kconfig_file(parsed_kconfig_options, args.config)
895 populate_with_data(config_checklist, parsed_kconfig_options, 'kconfig')
896 populate_with_data(config_checklist, kernel_version, 'version')
899 # populate the checklist with the parsed kconfig data
900 parsed_cmdline_options = OrderedDict()
901 parse_cmdline_file(parsed_cmdline_options, args.cmdline)
902 populate_with_data(config_checklist, parsed_cmdline_options, 'cmdline')
904 # now everything is ready for performing the checks
905 perform_checks(config_checklist)
907 # finally print the results
908 if mode == 'verbose':
909 print_unknown_options(config_checklist, parsed_kconfig_options)
910 print_checklist(mode, config_checklist, True)
914 sys.exit('[!] ERROR: checking cmdline doesn\'t work without checking kconfig')
917 if mode in ('show_ok', 'show_fail'):
918 sys.exit('[!] ERROR: wrong mode "{}" for --print'.format(mode))
920 add_kconfig_checks(config_checklist, arch)
921 add_cmdline_checks(config_checklist, arch)
923 print('[+] Printing kernel security hardening preferences for {}...'.format(arch))
924 print_checklist(mode, config_checklist, False)