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
31 from argparse import ArgumentParser
32 from collections import OrderedDict
35 debug_mode = False # set it to True to print the unknown options from the config
37 supported_archs = [ 'X86_64', 'X86_32', 'ARM64', 'ARM' ]
43 def __init__(self, name, expected, decision, reason):
45 self.expected = expected
46 self.decision = decision
52 if self.expected == self.state:
54 elif self.state is None:
55 if self.expected == 'is not set':
56 self.result = 'OK: not found'
58 self.result = 'FAIL: not found'
60 self.result = 'FAIL: "' + self.state + '"'
62 if self.result.startswith('OK'):
63 return True, self.result
65 return False, self.result
68 return '{} = {}'.format(self.name, self.state)
71 class ComplexOptCheck:
72 def __init__(self, *opts):
78 return self.opts[0].name
82 return self.opts[0].expected
86 return self.opts[0].state
90 return self.opts[0].decision
94 return self.opts[0].reason
97 class OR(ComplexOptCheck):
98 # self.opts[0] is the option which this OR-check is about.
100 # OR(<X_is_hardened>, <X_is_disabled>)
101 # OR(<X_is_hardened>, <X_is_hardened_old>)
105 sys.exit('[!] ERROR: invalid OR check')
107 for i, opt in enumerate(self.opts):
108 ret, msg = opt.check()
111 self.result = opt.result
113 self.result = 'OK: CONFIG_{} "{}"'.format(opt.name, opt.expected)
114 return True, self.result
115 self.result = self.opts[0].result
116 return False, self.result
119 def detect_arch(fname):
120 with open(fname, 'r') as f:
121 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
124 print('[+] Trying to detect architecture in "{}"...'.format(fname))
125 for line in f.readlines():
126 if arch_pattern.match(line):
127 option, value = line[7:].split('=', 1)
128 if option in supported_archs:
132 return None, 'more than one supported architecture is detected'
134 return None, 'failed to detect architecture'
139 def construct_checklist(arch):
140 modules_not_set = OptCheck('MODULES', 'is not set', 'kspp', 'cut_attack_surface')
141 devmem_not_set = OptCheck('DEVMEM', 'is not set', 'kspp', 'cut_attack_surface') # refers to LOCK_DOWN_KERNEL
143 checklist.append(OptCheck('BUG', 'y', 'defconfig', 'self_protection'))
144 checklist.append(OR(OptCheck('STRICT_KERNEL_RWX', 'y', 'defconfig', 'self_protection'), \
145 OptCheck('DEBUG_RODATA', 'y', 'defconfig', 'self_protection'))) # before v4.11
146 checklist.append(OR(OptCheck('STACKPROTECTOR_STRONG', 'y', 'defconfig', 'self_protection'), \
147 OptCheck('CC_STACKPROTECTOR_STRONG', 'y', 'defconfig', 'self_protection')))
148 checklist.append(OptCheck('SLUB_DEBUG', 'y', 'defconfig', 'self_protection'))
149 checklist.append(OR(OptCheck('STRICT_MODULE_RWX', 'y', 'defconfig', 'self_protection'), \
150 OptCheck('DEBUG_SET_MODULE_RONX', 'y', 'defconfig', 'self_protection'), \
151 modules_not_set)) # DEBUG_SET_MODULE_RONX was before v4.11
152 if debug_mode or arch == 'X86_64':
153 checklist.append(OptCheck('PAGE_TABLE_ISOLATION', 'y', 'defconfig', 'self_protection'))
154 checklist.append(OptCheck('RANDOMIZE_MEMORY', 'y', 'defconfig', 'self_protection'))
155 if debug_mode or arch == 'X86_64' or arch == 'X86_32':
156 checklist.append(OptCheck('RANDOMIZE_BASE', 'y', 'defconfig', 'self_protection'))
157 checklist.append(OptCheck('RETPOLINE', 'y', 'defconfig', 'self_protection'))
158 checklist.append(OptCheck('X86_SMAP', 'y', 'defconfig', 'self_protection'))
159 checklist.append(OptCheck('X86_INTEL_UMIP', 'y', 'defconfig', 'self_protection'))
160 checklist.append(OptCheck('SYN_COOKIES', 'y', 'defconfig', 'self_protection')) # another reason?
161 if debug_mode or arch == 'ARM64':
162 checklist.append(OptCheck('UNMAP_KERNEL_AT_EL0', 'y', 'defconfig', 'self_protection'))
163 if debug_mode or arch == 'X86_64' or arch == 'ARM64':
164 checklist.append(OptCheck('VMAP_STACK', 'y', 'defconfig', 'self_protection'))
165 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
166 checklist.append(OptCheck('THREAD_INFO_IN_TASK', 'y', 'defconfig', 'self_protection'))
167 if debug_mode or arch == 'ARM':
168 checklist.append(OptCheck('VMSPLIT_3G', 'y', 'defconfig', 'self_protection'))
169 checklist.append(OptCheck('CPU_SW_DOMAIN_PAN', 'y', 'defconfig', 'self_protection'))
170 if debug_mode or arch == 'ARM64' or arch == 'ARM':
171 checklist.append(OptCheck('REFCOUNT_FULL', 'y', 'defconfig', 'self_protection'))
173 checklist.append(OptCheck('BUG_ON_DATA_CORRUPTION', 'y', 'kspp', 'self_protection'))
174 checklist.append(OptCheck('DEBUG_WX', 'y', 'kspp', 'self_protection'))
175 checklist.append(OptCheck('SCHED_STACK_END_CHECK', 'y', 'kspp', 'self_protection'))
176 checklist.append(OptCheck('PAGE_POISONING', 'y', 'kspp', 'self_protection'))
177 checklist.append(OptCheck('SLAB_FREELIST_HARDENED', 'y', 'kspp', 'self_protection'))
178 checklist.append(OptCheck('SLAB_FREELIST_RANDOM', 'y', 'kspp', 'self_protection'))
179 checklist.append(OptCheck('HARDENED_USERCOPY', 'y', 'kspp', 'self_protection'))
180 checklist.append(OptCheck('HARDENED_USERCOPY_FALLBACK', 'is not set', 'kspp', 'self_protection'))
181 checklist.append(OptCheck('FORTIFY_SOURCE', 'y', 'kspp', 'self_protection'))
182 checklist.append(OptCheck('GCC_PLUGINS', 'y', 'kspp', 'self_protection'))
183 checklist.append(OptCheck('GCC_PLUGIN_RANDSTRUCT', 'y', 'kspp', 'self_protection'))
184 checklist.append(OptCheck('GCC_PLUGIN_STRUCTLEAK', 'y', 'kspp', 'self_protection'))
185 checklist.append(OptCheck('GCC_PLUGIN_STRUCTLEAK_BYREF_ALL', 'y', 'kspp', 'self_protection'))
186 checklist.append(OptCheck('GCC_PLUGIN_LATENT_ENTROPY', 'y', 'kspp', 'self_protection'))
187 checklist.append(OptCheck('DEBUG_LIST', 'y', 'kspp', 'self_protection'))
188 checklist.append(OptCheck('DEBUG_SG', 'y', 'kspp', 'self_protection'))
189 checklist.append(OptCheck('DEBUG_CREDENTIALS', 'y', 'kspp', 'self_protection'))
190 checklist.append(OptCheck('DEBUG_NOTIFIERS', 'y', 'kspp', 'self_protection'))
191 checklist.append(OR(OptCheck('MODULE_SIG', 'y', 'kspp', 'self_protection'), \
193 checklist.append(OR(OptCheck('MODULE_SIG_ALL', 'y', 'kspp', 'self_protection'), \
195 checklist.append(OR(OptCheck('MODULE_SIG_SHA512', 'y', 'kspp', 'self_protection'), \
197 checklist.append(OR(OptCheck('MODULE_SIG_FORCE', 'y', 'kspp', 'self_protection'), \
198 modules_not_set)) # refers to LOCK_DOWN_KERNEL
199 if debug_mode or arch == 'X86_64' or arch == 'X86_32':
200 checklist.append(OptCheck('DEFAULT_MMAP_MIN_ADDR', '65536', 'kspp', 'self_protection'))
201 checklist.append(OptCheck('REFCOUNT_FULL', 'y', 'kspp', 'self_protection'))
202 if debug_mode or arch == 'X86_32':
203 checklist.append(OptCheck('HIGHMEM64G', 'y', 'kspp', 'self_protection'))
204 checklist.append(OptCheck('X86_PAE', 'y', 'kspp', 'self_protection'))
205 if debug_mode or arch == 'ARM64':
206 checklist.append(OptCheck('ARM64_SW_TTBR0_PAN', 'y', 'kspp', 'self_protection'))
207 checklist.append(OptCheck('RANDOMIZE_BASE', 'y', 'kspp', 'self_protection'))
208 if debug_mode or arch == 'ARM64' or arch == 'ARM':
209 checklist.append(OptCheck('SYN_COOKIES', 'y', 'kspp', 'self_protection')) # another reason?
210 checklist.append(OptCheck('DEFAULT_MMAP_MIN_ADDR', '32768', 'kspp', 'self_protection'))
212 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
213 checklist.append(OptCheck('GCC_PLUGIN_STACKLEAK', 'y', 'my', 'self_protection'))
214 checklist.append(OptCheck('LOCK_DOWN_KERNEL', 'y', 'my', 'self_protection')) # remember about LOCK_DOWN_MANDATORY
215 checklist.append(OptCheck('SLUB_DEBUG_ON', 'y', 'my', 'self_protection'))
216 checklist.append(OptCheck('SECURITY_DMESG_RESTRICT', 'y', 'my', 'self_protection'))
217 checklist.append(OptCheck('STATIC_USERMODEHELPER', 'y', 'my', 'self_protection')) # needs userspace support (systemd)
218 checklist.append(OptCheck('SECURITY_LOADPIN', 'y', 'my', 'self_protection')) # needs userspace support
219 checklist.append(OptCheck('RESET_ATTACK_MITIGATION', 'y', 'my', 'self_protection')) # needs userspace support (systemd)
220 checklist.append(OptCheck('PAGE_POISONING_NO_SANITY', 'is not set', 'my', 'self_protection'))
221 checklist.append(OptCheck('PAGE_POISONING_ZERO', 'is not set', 'my', 'self_protection'))
222 checklist.append(OptCheck('SLAB_MERGE_DEFAULT', 'is not set', 'my', 'self_protection')) # slab_nomerge
223 if debug_mode or arch == 'X86_32':
224 checklist.append(OptCheck('PAGE_TABLE_ISOLATION', 'y', 'my', 'self_protection'))
226 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
227 checklist.append(OptCheck('SECURITY', 'y', 'defconfig', 'security_policy'))
228 if debug_mode or arch == 'ARM':
229 checklist.append(OptCheck('SECURITY', 'y', 'kspp', 'security_policy'))
230 checklist.append(OptCheck('SECURITY_YAMA', 'y', 'kspp', 'security_policy'))
231 checklist.append(OptCheck('SECURITY_SELINUX_DISABLE', 'is not set', 'kspp', 'security_policy'))
233 checklist.append(OptCheck('SECCOMP', 'y', 'defconfig', 'cut_attack_surface'))
234 checklist.append(OptCheck('SECCOMP_FILTER', 'y', 'defconfig', 'cut_attack_surface'))
235 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
236 checklist.append(OR(OptCheck('STRICT_DEVMEM', 'y', 'defconfig', 'cut_attack_surface'), \
237 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
239 checklist.append(modules_not_set)
240 checklist.append(devmem_not_set)
241 checklist.append(OR(OptCheck('IO_STRICT_DEVMEM', 'y', 'kspp', 'cut_attack_surface'), \
242 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
243 if debug_mode or arch == 'ARM':
244 checklist.append(OR(OptCheck('STRICT_DEVMEM', 'y', 'kspp', 'cut_attack_surface'), \
245 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
246 checklist.append(OptCheck('ACPI_CUSTOM_METHOD', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
247 checklist.append(OptCheck('COMPAT_BRK', 'is not set', 'kspp', 'cut_attack_surface'))
248 checklist.append(OptCheck('DEVKMEM', 'is not set', 'kspp', 'cut_attack_surface'))
249 checklist.append(OptCheck('COMPAT_VDSO', 'is not set', 'kspp', 'cut_attack_surface'))
250 checklist.append(OptCheck('BINFMT_MISC', 'is not set', 'kspp', 'cut_attack_surface'))
251 checklist.append(OptCheck('INET_DIAG', 'is not set', 'kspp', 'cut_attack_surface'))
252 checklist.append(OptCheck('KEXEC', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
253 checklist.append(OptCheck('PROC_KCORE', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
254 checklist.append(OptCheck('LEGACY_PTYS', 'is not set', 'kspp', 'cut_attack_surface'))
255 checklist.append(OptCheck('HIBERNATION', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
256 if debug_mode or arch == 'X86_64':
257 checklist.append(OptCheck('LEGACY_VSYSCALL_NONE', 'y', 'kspp', 'cut_attack_surface')) # 'vsyscall=none'
258 checklist.append(OptCheck('IA32_EMULATION', 'is not set', 'kspp', 'cut_attack_surface'))
259 checklist.append(OptCheck('X86_X32', 'is not set', 'kspp', 'cut_attack_surface'))
260 checklist.append(OptCheck('MODIFY_LDT_SYSCALL', 'is not set', 'kspp', 'cut_attack_surface'))
261 if debug_mode or arch == 'ARM':
262 checklist.append(OptCheck('OABI_COMPAT', 'is not set', 'kspp', 'cut_attack_surface'))
264 checklist.append(OptCheck('X86_PTDUMP', 'is not set', 'grsecurity', 'cut_attack_surface'))
265 checklist.append(OptCheck('ZSMALLOC_STAT', 'is not set', 'grsecurity', 'cut_attack_surface'))
266 checklist.append(OptCheck('PAGE_OWNER', 'is not set', 'grsecurity', 'cut_attack_surface'))
267 checklist.append(OptCheck('DEBUG_KMEMLEAK', 'is not set', 'grsecurity', 'cut_attack_surface'))
268 checklist.append(OptCheck('BINFMT_AOUT', 'is not set', 'grsecurity', 'cut_attack_surface'))
269 checklist.append(OptCheck('KPROBES', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
270 checklist.append(OptCheck('UPROBES', 'is not set', 'grsecurity', 'cut_attack_surface'))
271 checklist.append(OptCheck('GENERIC_TRACER', 'is not set', 'grsecurity', 'cut_attack_surface'))
272 checklist.append(OptCheck('PROC_VMCORE', 'is not set', 'grsecurity', 'cut_attack_surface'))
273 checklist.append(OptCheck('PROC_PAGE_MONITOR', 'is not set', 'grsecurity', 'cut_attack_surface'))
274 checklist.append(OptCheck('USELIB', 'is not set', 'grsecurity', 'cut_attack_surface'))
275 checklist.append(OptCheck('CHECKPOINT_RESTORE', 'is not set', 'grsecurity', 'cut_attack_surface'))
276 checklist.append(OptCheck('USERFAULTFD', 'is not set', 'grsecurity', 'cut_attack_surface'))
277 checklist.append(OptCheck('HWPOISON_INJECT', 'is not set', 'grsecurity', 'cut_attack_surface'))
278 checklist.append(OptCheck('MEM_SOFT_DIRTY', 'is not set', 'grsecurity', 'cut_attack_surface'))
279 checklist.append(OptCheck('DEVPORT', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
280 checklist.append(OptCheck('DEBUG_FS', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
281 checklist.append(OptCheck('NOTIFIER_ERROR_INJECTION','is not set', 'grsecurity', 'cut_attack_surface'))
283 checklist.append(OptCheck('ACPI_TABLE_UPGRADE', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
284 checklist.append(OptCheck('ACPI_APEI_EINJ', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
285 checklist.append(OptCheck('PROFILING', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
286 checklist.append(OptCheck('BPF_SYSCALL', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
287 checklist.append(OptCheck('MMIOTRACE_TEST', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
289 checklist.append(OptCheck('MMIOTRACE', 'is not set', 'my', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL (permissive)
290 checklist.append(OptCheck('KEXEC_FILE', 'is not set', 'my', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL (permissive)
291 checklist.append(OptCheck('LIVEPATCH', 'is not set', 'my', 'cut_attack_surface'))
292 checklist.append(OptCheck('USER_NS', 'is not set', 'my', 'cut_attack_surface')) # user.max_user_namespaces=0
293 checklist.append(OptCheck('IP_DCCP', 'is not set', 'my', 'cut_attack_surface'))
294 checklist.append(OptCheck('IP_SCTP', 'is not set', 'my', 'cut_attack_surface'))
295 checklist.append(OptCheck('FTRACE', 'is not set', 'my', 'cut_attack_surface'))
296 checklist.append(OptCheck('BPF_JIT', 'is not set', 'my', 'cut_attack_surface'))
297 if debug_mode or arch == 'X86_32':
298 checklist.append(OptCheck('MODIFY_LDT_SYSCALL', 'is not set', 'my', 'cut_attack_surface'))
300 if debug_mode or arch == 'X86_64' or arch == 'ARM64':
301 checklist.append(OptCheck('ARCH_MMAP_RND_BITS', '32', 'my', 'userspace_protection'))
302 if debug_mode or arch == 'X86_32' or arch == 'ARM':
303 checklist.append(OptCheck('ARCH_MMAP_RND_BITS', '16', 'my', 'userspace_protection'))
305 # checklist.append(OptCheck('LKDTM', 'm', 'my', 'feature_test'))
308 def print_checklist(arch):
309 print('[+] Printing kernel hardening preferences for {}...'.format(arch))
310 print(' {:<39}|{:^13}|{:^10}|{:^20}'.format(
311 'option name', 'desired val', 'decision', 'reason'))
312 print(' ' + '=' * 86)
313 for opt in checklist:
314 print(' CONFIG_{:<32}|{:^13}|{:^10}|{:^20}'.format(
315 opt.name, opt.expected, opt.decision, opt.reason))
319 def print_check_results():
320 print(' {:<39}|{:^13}|{:^10}|{:^20}||{:^28}'.format(
321 'option name', 'desired val', 'decision', 'reason', 'check result'))
322 print(' ' + '=' * 115)
323 for opt in checklist:
324 print(' CONFIG_{:<32}|{:^13}|{:^10}|{:^20}||{:^28}'.format(
325 opt.name, opt.expected, opt.decision, opt.reason, opt.result))
329 def get_option_state(options, name):
330 return options.get(name, None)
333 def perform_checks(parsed_options):
334 for opt in checklist:
335 if hasattr(opt, 'opts'):
337 o.state = get_option_state(parsed_options, o.name)
339 opt.state = get_option_state(parsed_options, opt.name)
343 def check_config_file(fname):
344 with open(fname, 'r') as f:
345 parsed_options = OrderedDict()
346 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
347 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
349 print('[+] Checking "{}" against hardening preferences...'.format(fname))
350 for line in f.readlines():
355 if opt_is_on.match(line):
356 option, value = line[7:].split('=', 1)
357 elif opt_is_off.match(line):
358 option, value = line[9:].split(' ', 1)
359 if value != 'is not set':
360 sys.exit('[!] ERROR: bad disabled config option "{}"'.format(line))
362 if option in parsed_options:
363 sys.exit('[!] ERROR: config option "{}" exists multiple times'.format(line))
365 if option is not None:
366 parsed_options[option] = value
368 perform_checks(parsed_options)
371 known_options = [opt.name for opt in checklist]
372 for option, value in parsed_options.items():
373 if option not in known_options:
374 print("DEBUG: dunno about option {} ({})".format(option, value))
376 print_check_results()
379 if __name__ == '__main__':
380 parser = ArgumentParser(description='Checks the hardening options in the Linux kernel config')
381 parser.add_argument('-p', '--print', choices=supported_archs,
382 help='print hardening preferences for selected architecture')
383 parser.add_argument('-c', '--config',
384 help='check the config_file against these preferences')
385 parser.add_argument('--debug', action='store_true',
386 help='enable internal debug mode')
387 args = parser.parse_args()
393 arch, msg = detect_arch(args.config)
395 sys.exit('[!] ERROR: {}'.format(msg))
397 print('[+] Detected architecture: {}'.format(arch))
399 construct_checklist(arch)
400 check_config_file(args.config)
401 error_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
405 print('[+] config check is PASSED')
408 sys.exit('[-] config check is NOT PASSED: {} errors'.format(error_count))
412 construct_checklist(arch)
413 print_checklist(arch)