4 # This script helps me to check the Linux kernel Kconfig option list
5 # against my 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:
18 # kernel.kptr_restrict=1
21 # Mitigations of CPU vulnerabilities:
23 # mitigations=auto,nosmt
27 # spec_store_bypass_disable=on
31 # ? CONFIG_HARDEN_BRANCH_PREDICTOR
35 # N.B. Hardening sysctl's:
36 # net.core.bpf_jit_harden
40 from argparse import ArgumentParser
41 from collections import OrderedDict
44 debug_mode = False # set it to True to print the unknown options from the config
46 supported_archs = [ 'X86_64', 'X86_32', 'ARM64', 'ARM' ]
52 def __init__(self, name, expected, decision, reason):
54 self.expected = expected
55 self.decision = decision
61 if self.expected == self.state:
63 elif self.state is None:
64 if self.expected == 'is not set':
65 self.result = 'OK: not found'
67 self.result = 'FAIL: not found'
69 self.result = 'FAIL: "' + self.state + '"'
71 if self.result.startswith('OK'):
72 return True, self.result
74 return False, self.result
77 return '{} = {}'.format(self.name, self.state)
80 class ComplexOptCheck:
81 def __init__(self, *opts):
87 return self.opts[0].name
91 return self.opts[0].expected
95 return self.opts[0].state
99 return self.opts[0].decision
103 return self.opts[0].reason
106 class OR(ComplexOptCheck):
107 # self.opts[0] is the option which this OR-check is about.
109 # OR(<X_is_hardened>, <X_is_disabled>)
110 # OR(<X_is_hardened>, <X_is_hardened_old>)
114 sys.exit('[!] ERROR: invalid OR check')
116 for i, opt in enumerate(self.opts):
117 ret, msg = opt.check()
120 self.result = opt.result
122 self.result = 'OK: CONFIG_{} "{}"'.format(opt.name, opt.expected)
123 return True, self.result
124 self.result = self.opts[0].result
125 return False, self.result
128 class AND(ComplexOptCheck):
129 # self.opts[0] is the option which this AND-check is about.
130 # Use case: AND(<suboption>, <main_option>)
131 # Suboption is not checked if checking of the main_option is failed.
134 for i, opt in reversed(list(enumerate(self.opts))):
135 ret, msg = opt.check()
137 self.result = opt.result
138 return ret, self.result
140 self.result = 'FAIL: CONFIG_{} is needed'.format(opt.name)
141 return False, self.result
143 sys.exit('[!] ERROR: invalid AND check')
146 def detect_arch(fname):
147 with open(fname, 'r') as f:
148 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
151 print('[+] Trying to detect architecture in "{}"...'.format(fname))
152 for line in f.readlines():
153 if arch_pattern.match(line):
154 option, value = line[7:].split('=', 1)
155 if option in supported_archs:
159 return None, 'more than one supported architecture is detected'
161 return None, 'failed to detect architecture'
166 def construct_checklist(arch):
167 modules_not_set = OptCheck('MODULES', 'is not set', 'kspp', 'cut_attack_surface')
168 devmem_not_set = OptCheck('DEVMEM', 'is not set', 'kspp', 'cut_attack_surface') # refers to LOCK_DOWN_KERNEL
170 checklist.append(OptCheck('BUG', 'y', 'defconfig', 'self_protection'))
171 checklist.append(OR(OptCheck('STRICT_KERNEL_RWX', 'y', 'defconfig', 'self_protection'), \
172 OptCheck('DEBUG_RODATA', 'y', 'defconfig', 'self_protection'))) # before v4.11
173 checklist.append(OR(OptCheck('STACKPROTECTOR_STRONG', 'y', 'defconfig', 'self_protection'), \
174 OptCheck('CC_STACKPROTECTOR_STRONG', 'y', 'defconfig', 'self_protection')))
175 checklist.append(OptCheck('SLUB_DEBUG', 'y', 'defconfig', 'self_protection'))
176 checklist.append(OR(OptCheck('STRICT_MODULE_RWX', 'y', 'defconfig', 'self_protection'), \
177 OptCheck('DEBUG_SET_MODULE_RONX', 'y', 'defconfig', 'self_protection'), \
178 modules_not_set)) # DEBUG_SET_MODULE_RONX was before v4.11
179 if debug_mode or arch == 'X86_64':
180 checklist.append(OptCheck('PAGE_TABLE_ISOLATION', 'y', 'defconfig', 'self_protection'))
181 checklist.append(OptCheck('RANDOMIZE_MEMORY', 'y', 'defconfig', 'self_protection'))
182 if debug_mode or arch == 'X86_64' or arch == 'X86_32':
183 checklist.append(OptCheck('RANDOMIZE_BASE', 'y', 'defconfig', 'self_protection'))
184 checklist.append(OptCheck('RETPOLINE', 'y', 'defconfig', 'self_protection'))
185 checklist.append(OptCheck('X86_SMAP', 'y', 'defconfig', 'self_protection'))
186 checklist.append(OptCheck('X86_INTEL_UMIP', 'y', 'defconfig', 'self_protection'))
187 checklist.append(OptCheck('SYN_COOKIES', 'y', 'defconfig', 'self_protection')) # another reason?
188 if debug_mode or arch == 'ARM64':
189 checklist.append(OptCheck('UNMAP_KERNEL_AT_EL0', 'y', 'defconfig', 'self_protection'))
190 if debug_mode or arch == 'X86_64' or arch == 'ARM64':
191 checklist.append(OptCheck('VMAP_STACK', 'y', 'defconfig', 'self_protection'))
192 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
193 checklist.append(OptCheck('THREAD_INFO_IN_TASK', 'y', 'defconfig', 'self_protection'))
194 if debug_mode or arch == 'ARM':
195 checklist.append(OptCheck('VMSPLIT_3G', 'y', 'defconfig', 'self_protection'))
196 checklist.append(OptCheck('CPU_SW_DOMAIN_PAN', 'y', 'defconfig', 'self_protection'))
197 if debug_mode or arch == 'ARM64' or arch == 'ARM':
198 checklist.append(OptCheck('REFCOUNT_FULL', 'y', 'defconfig', 'self_protection'))
200 checklist.append(OptCheck('BUG_ON_DATA_CORRUPTION', 'y', 'kspp', 'self_protection'))
201 checklist.append(OptCheck('DEBUG_WX', 'y', 'kspp', 'self_protection'))
202 checklist.append(OptCheck('SCHED_STACK_END_CHECK', 'y', 'kspp', 'self_protection'))
203 checklist.append(OptCheck('SLAB_FREELIST_HARDENED', 'y', 'kspp', 'self_protection'))
204 checklist.append(OptCheck('SLAB_FREELIST_RANDOM', 'y', 'kspp', 'self_protection'))
205 checklist.append(OptCheck('FORTIFY_SOURCE', 'y', 'kspp', 'self_protection'))
206 checklist.append(OptCheck('GCC_PLUGINS', 'y', 'kspp', 'self_protection'))
207 checklist.append(OptCheck('GCC_PLUGIN_RANDSTRUCT', 'y', 'kspp', 'self_protection'))
208 checklist.append(OptCheck('GCC_PLUGIN_STRUCTLEAK', 'y', 'kspp', 'self_protection'))
209 checklist.append(OptCheck('GCC_PLUGIN_STRUCTLEAK_BYREF_ALL', 'y', 'kspp', 'self_protection'))
210 checklist.append(OptCheck('GCC_PLUGIN_LATENT_ENTROPY', 'y', 'kspp', 'self_protection'))
211 checklist.append(OptCheck('DEBUG_LIST', 'y', 'kspp', 'self_protection'))
212 checklist.append(OptCheck('DEBUG_SG', 'y', 'kspp', 'self_protection'))
213 checklist.append(OptCheck('DEBUG_CREDENTIALS', 'y', 'kspp', 'self_protection'))
214 checklist.append(OptCheck('DEBUG_NOTIFIERS', 'y', 'kspp', 'self_protection'))
215 page_poisoning_is_set = OptCheck('PAGE_POISONING', 'y', 'kspp', 'self_protection')
216 checklist.append(page_poisoning_is_set)
217 hardened_usercopy_is_set = OptCheck('HARDENED_USERCOPY', 'y', 'kspp', 'self_protection')
218 checklist.append(hardened_usercopy_is_set)
219 checklist.append(AND(OptCheck('HARDENED_USERCOPY_FALLBACK', 'is not set', 'kspp', 'self_protection'), \
220 hardened_usercopy_is_set))
221 checklist.append(OR(OptCheck('MODULE_SIG', 'y', 'kspp', 'self_protection'), \
223 checklist.append(OR(OptCheck('MODULE_SIG_ALL', 'y', 'kspp', 'self_protection'), \
225 checklist.append(OR(OptCheck('MODULE_SIG_SHA512', 'y', 'kspp', 'self_protection'), \
227 checklist.append(OR(OptCheck('MODULE_SIG_FORCE', 'y', 'kspp', 'self_protection'), \
228 modules_not_set)) # refers to LOCK_DOWN_KERNEL
229 if debug_mode or arch == 'X86_64' or arch == 'X86_32':
230 checklist.append(OptCheck('DEFAULT_MMAP_MIN_ADDR', '65536', 'kspp', 'self_protection'))
231 checklist.append(OptCheck('REFCOUNT_FULL', 'y', 'kspp', 'self_protection'))
232 if debug_mode or arch == 'X86_32':
233 checklist.append(OptCheck('HIGHMEM64G', 'y', 'kspp', 'self_protection'))
234 checklist.append(OptCheck('X86_PAE', 'y', 'kspp', 'self_protection'))
235 if debug_mode or arch == 'ARM64':
236 checklist.append(OptCheck('ARM64_SW_TTBR0_PAN', 'y', 'kspp', 'self_protection'))
237 checklist.append(OptCheck('RANDOMIZE_BASE', 'y', 'kspp', 'self_protection'))
238 if debug_mode or arch == 'ARM64' or arch == 'ARM':
239 checklist.append(OptCheck('SYN_COOKIES', 'y', 'kspp', 'self_protection')) # another reason?
240 checklist.append(OptCheck('DEFAULT_MMAP_MIN_ADDR', '32768', 'kspp', 'self_protection'))
242 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
243 checklist.append(OptCheck('GCC_PLUGIN_STACKLEAK', 'y', 'my', 'self_protection'))
244 checklist.append(OptCheck('LOCK_DOWN_KERNEL', 'y', 'my', 'self_protection')) # remember about LOCK_DOWN_MANDATORY
245 checklist.append(OptCheck('SLUB_DEBUG_ON', 'y', 'my', 'self_protection'))
246 checklist.append(OptCheck('SECURITY_DMESG_RESTRICT', 'y', 'my', 'self_protection'))
247 checklist.append(OptCheck('STATIC_USERMODEHELPER', 'y', 'my', 'self_protection')) # needs userspace support (systemd)
248 checklist.append(OptCheck('SECURITY_LOADPIN', 'y', 'my', 'self_protection')) # needs userspace support
249 checklist.append(OptCheck('RESET_ATTACK_MITIGATION', 'y', 'my', 'self_protection')) # needs userspace support (systemd)
250 checklist.append(OptCheck('SLAB_MERGE_DEFAULT', 'is not set', 'my', 'self_protection')) # slab_nomerge
251 checklist.append(AND(OptCheck('PAGE_POISONING_NO_SANITY', 'is not set', 'my', 'self_protection'), \
252 page_poisoning_is_set))
253 checklist.append(AND(OptCheck('PAGE_POISONING_ZERO', 'is not set', 'my', 'self_protection'), \
254 page_poisoning_is_set))
255 if debug_mode or arch == 'X86_32':
256 checklist.append(OptCheck('PAGE_TABLE_ISOLATION', 'y', 'my', 'self_protection'))
257 if debug_mode or arch == 'ARM':
258 checklist.append(OptCheck('STACKPROTECTOR_PER_TASK', 'y', 'my', 'self_protection'))
260 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
261 checklist.append(OptCheck('SECURITY', 'y', 'defconfig', 'security_policy'))
262 if debug_mode or arch == 'ARM':
263 checklist.append(OptCheck('SECURITY', 'y', 'kspp', 'security_policy'))
264 checklist.append(OptCheck('SECURITY_YAMA', 'y', 'kspp', 'security_policy'))
265 checklist.append(OptCheck('SECURITY_SELINUX_DISABLE', 'is not set', 'kspp', 'security_policy'))
267 checklist.append(OptCheck('SECCOMP', 'y', 'defconfig', 'cut_attack_surface'))
268 checklist.append(OptCheck('SECCOMP_FILTER', 'y', 'defconfig', 'cut_attack_surface'))
269 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
270 checklist.append(OR(OptCheck('STRICT_DEVMEM', 'y', 'defconfig', 'cut_attack_surface'), \
271 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
273 checklist.append(modules_not_set)
274 checklist.append(devmem_not_set)
275 checklist.append(OR(OptCheck('IO_STRICT_DEVMEM', 'y', 'kspp', 'cut_attack_surface'), \
276 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
277 if debug_mode or arch == 'ARM':
278 checklist.append(OR(OptCheck('STRICT_DEVMEM', 'y', 'kspp', 'cut_attack_surface'), \
279 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
280 checklist.append(OptCheck('ACPI_CUSTOM_METHOD', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
281 checklist.append(OptCheck('COMPAT_BRK', 'is not set', 'kspp', 'cut_attack_surface'))
282 checklist.append(OptCheck('DEVKMEM', 'is not set', 'kspp', 'cut_attack_surface'))
283 checklist.append(OptCheck('COMPAT_VDSO', 'is not set', 'kspp', 'cut_attack_surface'))
284 checklist.append(OptCheck('BINFMT_MISC', 'is not set', 'kspp', 'cut_attack_surface'))
285 checklist.append(OptCheck('INET_DIAG', 'is not set', 'kspp', 'cut_attack_surface'))
286 checklist.append(OptCheck('KEXEC', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
287 checklist.append(OptCheck('PROC_KCORE', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
288 checklist.append(OptCheck('LEGACY_PTYS', 'is not set', 'kspp', 'cut_attack_surface'))
289 checklist.append(OptCheck('HIBERNATION', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
290 if debug_mode or arch == 'X86_64':
291 checklist.append(OptCheck('LEGACY_VSYSCALL_NONE', 'y', 'kspp', 'cut_attack_surface')) # 'vsyscall=none'
292 checklist.append(OptCheck('IA32_EMULATION', 'is not set', 'kspp', 'cut_attack_surface'))
293 checklist.append(OptCheck('X86_X32', 'is not set', 'kspp', 'cut_attack_surface'))
294 checklist.append(OptCheck('MODIFY_LDT_SYSCALL', 'is not set', 'kspp', 'cut_attack_surface'))
295 if debug_mode or arch == 'ARM':
296 checklist.append(OptCheck('OABI_COMPAT', 'is not set', 'kspp', 'cut_attack_surface'))
298 checklist.append(OptCheck('X86_PTDUMP', 'is not set', 'grsecurity', 'cut_attack_surface'))
299 checklist.append(OptCheck('ZSMALLOC_STAT', 'is not set', 'grsecurity', 'cut_attack_surface'))
300 checklist.append(OptCheck('PAGE_OWNER', 'is not set', 'grsecurity', 'cut_attack_surface'))
301 checklist.append(OptCheck('DEBUG_KMEMLEAK', 'is not set', 'grsecurity', 'cut_attack_surface'))
302 checklist.append(OptCheck('BINFMT_AOUT', 'is not set', 'grsecurity', 'cut_attack_surface'))
303 checklist.append(OptCheck('KPROBES', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
304 checklist.append(OptCheck('UPROBES', 'is not set', 'grsecurity', 'cut_attack_surface'))
305 checklist.append(OptCheck('GENERIC_TRACER', 'is not set', 'grsecurity', 'cut_attack_surface'))
306 checklist.append(OptCheck('PROC_VMCORE', 'is not set', 'grsecurity', 'cut_attack_surface'))
307 checklist.append(OptCheck('PROC_PAGE_MONITOR', 'is not set', 'grsecurity', 'cut_attack_surface'))
308 checklist.append(OptCheck('USELIB', 'is not set', 'grsecurity', 'cut_attack_surface'))
309 checklist.append(OptCheck('CHECKPOINT_RESTORE', 'is not set', 'grsecurity', 'cut_attack_surface'))
310 checklist.append(OptCheck('USERFAULTFD', 'is not set', 'grsecurity', 'cut_attack_surface'))
311 checklist.append(OptCheck('HWPOISON_INJECT', 'is not set', 'grsecurity', 'cut_attack_surface'))
312 checklist.append(OptCheck('MEM_SOFT_DIRTY', 'is not set', 'grsecurity', 'cut_attack_surface'))
313 checklist.append(OptCheck('DEVPORT', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
314 checklist.append(OptCheck('DEBUG_FS', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
315 checklist.append(OptCheck('NOTIFIER_ERROR_INJECTION','is not set', 'grsecurity', 'cut_attack_surface'))
317 checklist.append(OptCheck('ACPI_TABLE_UPGRADE', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
318 checklist.append(OptCheck('ACPI_APEI_EINJ', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
319 checklist.append(OptCheck('PROFILING', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
320 checklist.append(OptCheck('BPF_SYSCALL', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
321 checklist.append(OptCheck('MMIOTRACE_TEST', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
323 checklist.append(OptCheck('MMIOTRACE', 'is not set', 'my', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL (permissive)
324 checklist.append(OptCheck('KEXEC_FILE', 'is not set', 'my', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL (permissive)
325 checklist.append(OptCheck('LIVEPATCH', 'is not set', 'my', 'cut_attack_surface'))
326 checklist.append(OptCheck('USER_NS', 'is not set', 'my', 'cut_attack_surface')) # user.max_user_namespaces=0
327 checklist.append(OptCheck('IP_DCCP', 'is not set', 'my', 'cut_attack_surface'))
328 checklist.append(OptCheck('IP_SCTP', 'is not set', 'my', 'cut_attack_surface'))
329 checklist.append(OptCheck('FTRACE', 'is not set', 'my', 'cut_attack_surface'))
330 checklist.append(OptCheck('BPF_JIT', 'is not set', 'my', 'cut_attack_surface'))
331 if debug_mode or arch == 'X86_32':
332 checklist.append(OptCheck('MODIFY_LDT_SYSCALL', 'is not set', 'my', 'cut_attack_surface'))
334 if debug_mode or arch == 'ARM64':
335 checklist.append(OptCheck('ARM64_PTR_AUTH', 'y', 'defconfig', 'userspace_protection'))
336 if debug_mode or arch == 'X86_64' or arch == 'ARM64':
337 checklist.append(OptCheck('ARCH_MMAP_RND_BITS', '32', 'my', 'userspace_protection'))
338 if debug_mode or arch == 'X86_32' or arch == 'ARM':
339 checklist.append(OptCheck('ARCH_MMAP_RND_BITS', '16', 'my', 'userspace_protection'))
341 # checklist.append(OptCheck('LKDTM', 'm', 'my', 'feature_test'))
344 def print_checklist(arch):
345 print('[+] Printing kernel hardening preferences for {}...'.format(arch))
346 print('{:^40}|{:^13}|{:^10}|{:^20}'.format(
347 'option name', 'desired val', 'decision', 'reason'))
349 for opt in checklist:
350 print('CONFIG_{:<33}|{:^13}|{:^10}|{:^20}'.format(
351 opt.name, opt.expected, opt.decision, opt.reason))
355 def print_check_results():
356 print('{:^40}|{:^13}|{:^10}|{:^20}||{:^28}'.format(
357 'option name', 'desired val', 'decision', 'reason', 'check result'))
359 for opt in checklist:
360 print('CONFIG_{:<33}|{:^13}|{:^10}|{:^20}||{:^28}'.format(
361 opt.name, opt.expected, opt.decision, opt.reason, opt.result))
365 def get_option_state(options, name):
366 return options.get(name, None)
369 def perform_checks(parsed_options):
370 for opt in checklist:
371 if hasattr(opt, 'opts'):
373 o.state = get_option_state(parsed_options, o.name)
375 opt.state = get_option_state(parsed_options, opt.name)
379 def check_config_file(fname):
380 with open(fname, 'r') as f:
381 parsed_options = OrderedDict()
382 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
383 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
385 print('[+] Checking "{}" against hardening preferences...'.format(fname))
386 for line in f.readlines():
391 if opt_is_on.match(line):
392 option, value = line[7:].split('=', 1)
393 elif opt_is_off.match(line):
394 option, value = line[9:].split(' ', 1)
395 if value != 'is not set':
396 sys.exit('[!] ERROR: bad disabled config option "{}"'.format(line))
398 if option in parsed_options:
399 sys.exit('[!] ERROR: config option "{}" exists multiple times'.format(line))
401 if option is not None:
402 parsed_options[option] = value
404 perform_checks(parsed_options)
407 known_options = [opt.name for opt in checklist]
408 for option, value in parsed_options.items():
409 if option not in known_options:
410 print("DEBUG: dunno about option {} ({})".format(option, value))
412 print_check_results()
415 if __name__ == '__main__':
416 parser = ArgumentParser(description='Checks the hardening options in the Linux kernel config')
417 parser.add_argument('-p', '--print', choices=supported_archs,
418 help='print hardening preferences for selected architecture')
419 parser.add_argument('-c', '--config',
420 help='check the config_file against these preferences')
421 parser.add_argument('--debug', action='store_true',
422 help='enable internal debug mode')
423 args = parser.parse_args()
429 arch, msg = detect_arch(args.config)
431 sys.exit('[!] ERROR: {}'.format(msg))
433 print('[+] Detected architecture: {}'.format(arch))
435 construct_checklist(arch)
436 check_config_file(args.config)
437 error_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
438 ok_count = len(list(filter(lambda opt: opt.result.startswith('OK'), checklist)))
441 print('[+] config check is finished: \'OK\' - {} / \'FAIL\' - {}'.format(ok_count, error_count))
446 construct_checklist(arch)
447 print_checklist(arch)