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
23 # spec_store_bypass_disable=on
27 # N.B. Hardening sysctl's:
28 # net.core.bpf_jit_harden
32 from argparse import ArgumentParser
33 from collections import OrderedDict
36 debug_mode = False # set it to True to print the unknown options from the config
38 supported_archs = [ 'X86_64', 'X86_32', 'ARM64', 'ARM' ]
44 def __init__(self, name, expected, decision, reason):
46 self.expected = expected
47 self.decision = decision
53 if self.expected == self.state:
55 elif self.state is None:
56 if self.expected == 'is not set':
57 self.result = 'OK: not found'
59 self.result = 'FAIL: not found'
61 self.result = 'FAIL: "' + self.state + '"'
63 if self.result.startswith('OK'):
64 return True, self.result
66 return False, self.result
69 return '{} = {}'.format(self.name, self.state)
72 class ComplexOptCheck:
73 def __init__(self, *opts):
79 return self.opts[0].name
83 return self.opts[0].expected
87 return self.opts[0].state
91 return self.opts[0].decision
95 return self.opts[0].reason
98 class OR(ComplexOptCheck):
99 # self.opts[0] is the option which this OR-check is about.
101 # OR(<X_is_hardened>, <X_is_disabled>)
102 # OR(<X_is_hardened>, <X_is_hardened_old>)
106 sys.exit('[!] ERROR: invalid OR check')
108 for i, opt in enumerate(self.opts):
109 ret, msg = opt.check()
112 self.result = opt.result
114 self.result = 'OK: CONFIG_{} "{}"'.format(opt.name, opt.expected)
115 return True, self.result
116 self.result = self.opts[0].result
117 return False, self.result
120 class AND(ComplexOptCheck):
121 # self.opts[0] is the option which this AND-check is about.
122 # Use case: AND(<suboption>, <main_option>)
123 # Suboption is not checked if checking of the main_option is failed.
126 for i, opt in reversed(list(enumerate(self.opts))):
127 ret, msg = opt.check()
129 self.result = opt.result
130 return ret, self.result
132 self.result = 'FAIL: CONFIG_{} is needed'.format(opt.name)
133 return False, self.result
135 sys.exit('[!] ERROR: invalid AND check')
138 def detect_arch(fname):
139 with open(fname, 'r') as f:
140 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
143 print('[+] Trying to detect architecture in "{}"...'.format(fname))
144 for line in f.readlines():
145 if arch_pattern.match(line):
146 option, value = line[7:].split('=', 1)
147 if option in supported_archs:
151 return None, 'more than one supported architecture is detected'
153 return None, 'failed to detect architecture'
158 def construct_checklist(arch):
159 modules_not_set = OptCheck('MODULES', 'is not set', 'kspp', 'cut_attack_surface')
160 devmem_not_set = OptCheck('DEVMEM', 'is not set', 'kspp', 'cut_attack_surface') # refers to LOCK_DOWN_KERNEL
162 checklist.append(OptCheck('BUG', 'y', 'defconfig', 'self_protection'))
163 checklist.append(OR(OptCheck('STRICT_KERNEL_RWX', 'y', 'defconfig', 'self_protection'), \
164 OptCheck('DEBUG_RODATA', 'y', 'defconfig', 'self_protection'))) # before v4.11
165 checklist.append(OR(OptCheck('STACKPROTECTOR_STRONG', 'y', 'defconfig', 'self_protection'), \
166 OptCheck('CC_STACKPROTECTOR_STRONG', 'y', 'defconfig', 'self_protection')))
167 checklist.append(OptCheck('SLUB_DEBUG', 'y', 'defconfig', 'self_protection'))
168 checklist.append(OR(OptCheck('STRICT_MODULE_RWX', 'y', 'defconfig', 'self_protection'), \
169 OptCheck('DEBUG_SET_MODULE_RONX', 'y', 'defconfig', 'self_protection'), \
170 modules_not_set)) # DEBUG_SET_MODULE_RONX was before v4.11
171 if debug_mode or arch == 'X86_64':
172 checklist.append(OptCheck('PAGE_TABLE_ISOLATION', 'y', 'defconfig', 'self_protection'))
173 checklist.append(OptCheck('RANDOMIZE_MEMORY', 'y', 'defconfig', 'self_protection'))
174 if debug_mode or arch == 'X86_64' or arch == 'X86_32':
175 checklist.append(OptCheck('RANDOMIZE_BASE', 'y', 'defconfig', 'self_protection'))
176 checklist.append(OptCheck('RETPOLINE', 'y', 'defconfig', 'self_protection'))
177 checklist.append(OptCheck('X86_SMAP', 'y', 'defconfig', 'self_protection'))
178 checklist.append(OptCheck('X86_INTEL_UMIP', 'y', 'defconfig', 'self_protection'))
179 checklist.append(OptCheck('SYN_COOKIES', 'y', 'defconfig', 'self_protection')) # another reason?
180 if debug_mode or arch == 'ARM64':
181 checklist.append(OptCheck('UNMAP_KERNEL_AT_EL0', 'y', 'defconfig', 'self_protection'))
182 if debug_mode or arch == 'X86_64' or arch == 'ARM64':
183 checklist.append(OptCheck('VMAP_STACK', 'y', 'defconfig', 'self_protection'))
184 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
185 checklist.append(OptCheck('THREAD_INFO_IN_TASK', 'y', 'defconfig', 'self_protection'))
186 if debug_mode or arch == 'ARM':
187 checklist.append(OptCheck('VMSPLIT_3G', 'y', 'defconfig', 'self_protection'))
188 checklist.append(OptCheck('CPU_SW_DOMAIN_PAN', 'y', 'defconfig', 'self_protection'))
189 if debug_mode or arch == 'ARM64' or arch == 'ARM':
190 checklist.append(OptCheck('REFCOUNT_FULL', 'y', 'defconfig', 'self_protection'))
192 checklist.append(OptCheck('BUG_ON_DATA_CORRUPTION', 'y', 'kspp', 'self_protection'))
193 checklist.append(OptCheck('DEBUG_WX', 'y', 'kspp', 'self_protection'))
194 checklist.append(OptCheck('SCHED_STACK_END_CHECK', 'y', 'kspp', 'self_protection'))
195 checklist.append(OptCheck('SLAB_FREELIST_HARDENED', 'y', 'kspp', 'self_protection'))
196 checklist.append(OptCheck('SLAB_FREELIST_RANDOM', 'y', 'kspp', 'self_protection'))
197 checklist.append(OptCheck('FORTIFY_SOURCE', 'y', 'kspp', 'self_protection'))
198 checklist.append(OptCheck('GCC_PLUGINS', 'y', 'kspp', 'self_protection'))
199 checklist.append(OptCheck('GCC_PLUGIN_RANDSTRUCT', 'y', 'kspp', 'self_protection'))
200 checklist.append(OptCheck('GCC_PLUGIN_STRUCTLEAK', 'y', 'kspp', 'self_protection'))
201 checklist.append(OptCheck('GCC_PLUGIN_STRUCTLEAK_BYREF_ALL', 'y', 'kspp', 'self_protection'))
202 checklist.append(OptCheck('GCC_PLUGIN_LATENT_ENTROPY', 'y', 'kspp', 'self_protection'))
203 checklist.append(OptCheck('DEBUG_LIST', 'y', 'kspp', 'self_protection'))
204 checklist.append(OptCheck('DEBUG_SG', 'y', 'kspp', 'self_protection'))
205 checklist.append(OptCheck('DEBUG_CREDENTIALS', 'y', 'kspp', 'self_protection'))
206 checklist.append(OptCheck('DEBUG_NOTIFIERS', 'y', 'kspp', 'self_protection'))
207 page_poisoning_is_set = OptCheck('PAGE_POISONING', 'y', 'kspp', 'self_protection')
208 checklist.append(page_poisoning_is_set)
209 hardened_usercopy_is_set = OptCheck('HARDENED_USERCOPY', 'y', 'kspp', 'self_protection')
210 checklist.append(hardened_usercopy_is_set)
211 checklist.append(AND(OptCheck('HARDENED_USERCOPY_FALLBACK', 'is not set', 'kspp', 'self_protection'), \
212 hardened_usercopy_is_set))
213 checklist.append(OR(OptCheck('MODULE_SIG', 'y', 'kspp', 'self_protection'), \
215 checklist.append(OR(OptCheck('MODULE_SIG_ALL', 'y', 'kspp', 'self_protection'), \
217 checklist.append(OR(OptCheck('MODULE_SIG_SHA512', 'y', 'kspp', 'self_protection'), \
219 checklist.append(OR(OptCheck('MODULE_SIG_FORCE', 'y', 'kspp', 'self_protection'), \
220 modules_not_set)) # refers to LOCK_DOWN_KERNEL
221 if debug_mode or arch == 'X86_64' or arch == 'X86_32':
222 checklist.append(OptCheck('DEFAULT_MMAP_MIN_ADDR', '65536', 'kspp', 'self_protection'))
223 checklist.append(OptCheck('REFCOUNT_FULL', 'y', 'kspp', 'self_protection'))
224 if debug_mode or arch == 'X86_32':
225 checklist.append(OptCheck('HIGHMEM64G', 'y', 'kspp', 'self_protection'))
226 checklist.append(OptCheck('X86_PAE', 'y', 'kspp', 'self_protection'))
227 if debug_mode or arch == 'ARM64':
228 checklist.append(OptCheck('ARM64_SW_TTBR0_PAN', 'y', 'kspp', 'self_protection'))
229 checklist.append(OptCheck('RANDOMIZE_BASE', 'y', 'kspp', 'self_protection'))
230 if debug_mode or arch == 'ARM64' or arch == 'ARM':
231 checklist.append(OptCheck('SYN_COOKIES', 'y', 'kspp', 'self_protection')) # another reason?
232 checklist.append(OptCheck('DEFAULT_MMAP_MIN_ADDR', '32768', 'kspp', 'self_protection'))
234 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
235 checklist.append(OptCheck('GCC_PLUGIN_STACKLEAK', 'y', 'my', 'self_protection'))
236 checklist.append(OptCheck('LOCK_DOWN_KERNEL', 'y', 'my', 'self_protection')) # remember about LOCK_DOWN_MANDATORY
237 checklist.append(OptCheck('SLUB_DEBUG_ON', 'y', 'my', 'self_protection'))
238 checklist.append(OptCheck('SECURITY_DMESG_RESTRICT', 'y', 'my', 'self_protection'))
239 checklist.append(OptCheck('STATIC_USERMODEHELPER', 'y', 'my', 'self_protection')) # needs userspace support (systemd)
240 checklist.append(OptCheck('SECURITY_LOADPIN', 'y', 'my', 'self_protection')) # needs userspace support
241 checklist.append(OptCheck('RESET_ATTACK_MITIGATION', 'y', 'my', 'self_protection')) # needs userspace support (systemd)
242 checklist.append(OptCheck('SLAB_MERGE_DEFAULT', 'is not set', 'my', 'self_protection')) # slab_nomerge
243 checklist.append(AND(OptCheck('PAGE_POISONING_NO_SANITY', 'is not set', 'my', 'self_protection'), \
244 page_poisoning_is_set))
245 checklist.append(AND(OptCheck('PAGE_POISONING_ZERO', 'is not set', 'my', 'self_protection'), \
246 page_poisoning_is_set))
247 if debug_mode or arch == 'X86_32':
248 checklist.append(OptCheck('PAGE_TABLE_ISOLATION', 'y', 'my', 'self_protection'))
249 if debug_mode or arch == 'ARM':
250 checklist.append(OptCheck('STACKPROTECTOR_PER_TASK', 'y', 'my', 'self_protection'))
252 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
253 checklist.append(OptCheck('SECURITY', 'y', 'defconfig', 'security_policy'))
254 if debug_mode or arch == 'ARM':
255 checklist.append(OptCheck('SECURITY', 'y', 'kspp', 'security_policy'))
256 checklist.append(OptCheck('SECURITY_YAMA', 'y', 'kspp', 'security_policy'))
257 checklist.append(OptCheck('SECURITY_SELINUX_DISABLE', 'is not set', 'kspp', 'security_policy'))
259 checklist.append(OptCheck('SECCOMP', 'y', 'defconfig', 'cut_attack_surface'))
260 checklist.append(OptCheck('SECCOMP_FILTER', 'y', 'defconfig', 'cut_attack_surface'))
261 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
262 checklist.append(OR(OptCheck('STRICT_DEVMEM', 'y', 'defconfig', 'cut_attack_surface'), \
263 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
265 checklist.append(modules_not_set)
266 checklist.append(devmem_not_set)
267 checklist.append(OR(OptCheck('IO_STRICT_DEVMEM', 'y', 'kspp', 'cut_attack_surface'), \
268 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
269 if debug_mode or arch == 'ARM':
270 checklist.append(OR(OptCheck('STRICT_DEVMEM', 'y', 'kspp', 'cut_attack_surface'), \
271 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
272 checklist.append(OptCheck('ACPI_CUSTOM_METHOD', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
273 checklist.append(OptCheck('COMPAT_BRK', 'is not set', 'kspp', 'cut_attack_surface'))
274 checklist.append(OptCheck('DEVKMEM', 'is not set', 'kspp', 'cut_attack_surface'))
275 checklist.append(OptCheck('COMPAT_VDSO', 'is not set', 'kspp', 'cut_attack_surface'))
276 checklist.append(OptCheck('BINFMT_MISC', 'is not set', 'kspp', 'cut_attack_surface'))
277 checklist.append(OptCheck('INET_DIAG', 'is not set', 'kspp', 'cut_attack_surface'))
278 checklist.append(OptCheck('KEXEC', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
279 checklist.append(OptCheck('PROC_KCORE', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
280 checklist.append(OptCheck('LEGACY_PTYS', 'is not set', 'kspp', 'cut_attack_surface'))
281 checklist.append(OptCheck('HIBERNATION', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
282 if debug_mode or arch == 'X86_64':
283 checklist.append(OptCheck('LEGACY_VSYSCALL_NONE', 'y', 'kspp', 'cut_attack_surface')) # 'vsyscall=none'
284 checklist.append(OptCheck('IA32_EMULATION', 'is not set', 'kspp', 'cut_attack_surface'))
285 checklist.append(OptCheck('X86_X32', 'is not set', 'kspp', 'cut_attack_surface'))
286 checklist.append(OptCheck('MODIFY_LDT_SYSCALL', 'is not set', 'kspp', 'cut_attack_surface'))
287 if debug_mode or arch == 'ARM':
288 checklist.append(OptCheck('OABI_COMPAT', 'is not set', 'kspp', 'cut_attack_surface'))
290 checklist.append(OptCheck('X86_PTDUMP', 'is not set', 'grsecurity', 'cut_attack_surface'))
291 checklist.append(OptCheck('ZSMALLOC_STAT', 'is not set', 'grsecurity', 'cut_attack_surface'))
292 checklist.append(OptCheck('PAGE_OWNER', 'is not set', 'grsecurity', 'cut_attack_surface'))
293 checklist.append(OptCheck('DEBUG_KMEMLEAK', 'is not set', 'grsecurity', 'cut_attack_surface'))
294 checklist.append(OptCheck('BINFMT_AOUT', 'is not set', 'grsecurity', 'cut_attack_surface'))
295 checklist.append(OptCheck('KPROBES', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
296 checklist.append(OptCheck('UPROBES', 'is not set', 'grsecurity', 'cut_attack_surface'))
297 checklist.append(OptCheck('GENERIC_TRACER', 'is not set', 'grsecurity', 'cut_attack_surface'))
298 checklist.append(OptCheck('PROC_VMCORE', 'is not set', 'grsecurity', 'cut_attack_surface'))
299 checklist.append(OptCheck('PROC_PAGE_MONITOR', 'is not set', 'grsecurity', 'cut_attack_surface'))
300 checklist.append(OptCheck('USELIB', 'is not set', 'grsecurity', 'cut_attack_surface'))
301 checklist.append(OptCheck('CHECKPOINT_RESTORE', 'is not set', 'grsecurity', 'cut_attack_surface'))
302 checklist.append(OptCheck('USERFAULTFD', 'is not set', 'grsecurity', 'cut_attack_surface'))
303 checklist.append(OptCheck('HWPOISON_INJECT', 'is not set', 'grsecurity', 'cut_attack_surface'))
304 checklist.append(OptCheck('MEM_SOFT_DIRTY', 'is not set', 'grsecurity', 'cut_attack_surface'))
305 checklist.append(OptCheck('DEVPORT', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
306 checklist.append(OptCheck('DEBUG_FS', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
307 checklist.append(OptCheck('NOTIFIER_ERROR_INJECTION','is not set', 'grsecurity', 'cut_attack_surface'))
309 checklist.append(OptCheck('ACPI_TABLE_UPGRADE', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
310 checklist.append(OptCheck('ACPI_APEI_EINJ', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
311 checklist.append(OptCheck('PROFILING', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
312 checklist.append(OptCheck('BPF_SYSCALL', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
313 checklist.append(OptCheck('MMIOTRACE_TEST', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
315 checklist.append(OptCheck('MMIOTRACE', 'is not set', 'my', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL (permissive)
316 checklist.append(OptCheck('KEXEC_FILE', 'is not set', 'my', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL (permissive)
317 checklist.append(OptCheck('LIVEPATCH', 'is not set', 'my', 'cut_attack_surface'))
318 checklist.append(OptCheck('USER_NS', 'is not set', 'my', 'cut_attack_surface')) # user.max_user_namespaces=0
319 checklist.append(OptCheck('IP_DCCP', 'is not set', 'my', 'cut_attack_surface'))
320 checklist.append(OptCheck('IP_SCTP', 'is not set', 'my', 'cut_attack_surface'))
321 checklist.append(OptCheck('FTRACE', 'is not set', 'my', 'cut_attack_surface'))
322 checklist.append(OptCheck('BPF_JIT', 'is not set', 'my', 'cut_attack_surface'))
323 if debug_mode or arch == 'X86_32':
324 checklist.append(OptCheck('MODIFY_LDT_SYSCALL', 'is not set', 'my', 'cut_attack_surface'))
326 if debug_mode or arch == 'ARM64':
327 checklist.append(OptCheck('ARM64_PTR_AUTH', 'y', 'defconfig', 'userspace_protection'))
328 if debug_mode or arch == 'X86_64' or arch == 'ARM64':
329 checklist.append(OptCheck('ARCH_MMAP_RND_BITS', '32', 'my', 'userspace_protection'))
330 if debug_mode or arch == 'X86_32' or arch == 'ARM':
331 checklist.append(OptCheck('ARCH_MMAP_RND_BITS', '16', 'my', 'userspace_protection'))
333 # checklist.append(OptCheck('LKDTM', 'm', 'my', 'feature_test'))
336 def print_checklist(arch):
337 print('[+] Printing kernel hardening preferences for {}...'.format(arch))
338 print(' {:<39}|{:^13}|{:^10}|{:^20}'.format(
339 'option name', 'desired val', 'decision', 'reason'))
340 print(' ' + '=' * 86)
341 for opt in checklist:
342 print(' CONFIG_{:<32}|{:^13}|{:^10}|{:^20}'.format(
343 opt.name, opt.expected, opt.decision, opt.reason))
347 def print_check_results():
348 print(' {:<39}|{:^13}|{:^10}|{:^20}||{:^28}'.format(
349 'option name', 'desired val', 'decision', 'reason', 'check result'))
350 print(' ' + '=' * 115)
351 for opt in checklist:
352 print(' CONFIG_{:<32}|{:^13}|{:^10}|{:^20}||{:^28}'.format(
353 opt.name, opt.expected, opt.decision, opt.reason, opt.result))
357 def get_option_state(options, name):
358 return options.get(name, None)
361 def perform_checks(parsed_options):
362 for opt in checklist:
363 if hasattr(opt, 'opts'):
365 o.state = get_option_state(parsed_options, o.name)
367 opt.state = get_option_state(parsed_options, opt.name)
371 def check_config_file(fname):
372 with open(fname, 'r') as f:
373 parsed_options = OrderedDict()
374 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
375 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
377 print('[+] Checking "{}" against hardening preferences...'.format(fname))
378 for line in f.readlines():
383 if opt_is_on.match(line):
384 option, value = line[7:].split('=', 1)
385 elif opt_is_off.match(line):
386 option, value = line[9:].split(' ', 1)
387 if value != 'is not set':
388 sys.exit('[!] ERROR: bad disabled config option "{}"'.format(line))
390 if option in parsed_options:
391 sys.exit('[!] ERROR: config option "{}" exists multiple times'.format(line))
393 if option is not None:
394 parsed_options[option] = value
396 perform_checks(parsed_options)
399 known_options = [opt.name for opt in checklist]
400 for option, value in parsed_options.items():
401 if option not in known_options:
402 print("DEBUG: dunno about option {} ({})".format(option, value))
404 print_check_results()
407 if __name__ == '__main__':
408 parser = ArgumentParser(description='Checks the hardening options in the Linux kernel config')
409 parser.add_argument('-p', '--print', choices=supported_archs,
410 help='print hardening preferences for selected architecture')
411 parser.add_argument('-c', '--config',
412 help='check the config_file against these preferences')
413 parser.add_argument('--debug', action='store_true',
414 help='enable internal debug mode')
415 args = parser.parse_args()
421 arch, msg = detect_arch(args.config)
423 sys.exit('[!] ERROR: {}'.format(msg))
425 print('[+] Detected architecture: {}'.format(arch))
427 construct_checklist(arch)
428 check_config_file(args.config)
429 error_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
430 ok_count = len(list(filter(lambda opt: opt.result.startswith('OK'), checklist)))
433 print('[+] config check is finished: \'OK\' - {} / \'FAIL\' - {}'.format(ok_count, error_count))
438 construct_checklist(arch)
439 print_checklist(arch)