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)
72 def __init__(self, *opts):
76 # self.opts[0] is the option which this OR-check is about.
77 # Use case: OR(<X_is_hardened>, <X_is_disabled>)
81 return self.opts[0].name
85 return self.opts[0].expected
89 return self.opts[0].state
93 return self.opts[0].decision
97 return self.opts[0].reason
100 for i, opt in enumerate(self.opts):
101 result, msg = opt.check()
104 self.result = opt.result
106 self.result = 'CONFIG_{}: {} ("{}")'.format(opt.name, opt.result, opt.expected)
107 return True, self.result
108 self.result = self.opts[0].result
109 return False, self.result
112 def detect_arch(fname):
113 with open(fname, 'r') as f:
114 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
117 print('[+] Trying to detect architecture in "{}"...'.format(fname))
118 for line in f.readlines():
119 if arch_pattern.match(line):
120 option, value = line[7:].split('=', 1)
121 if option in supported_archs:
125 return None, 'more than one supported architecture is detected'
127 return None, 'failed to detect architecture'
132 def construct_checklist(arch):
133 modules_not_set = OptCheck('MODULES', 'is not set', 'kspp', 'cut_attack_surface')
134 devmem_not_set = OptCheck('DEVMEM', 'is not set', 'kspp', 'cut_attack_surface') # refers to LOCK_DOWN_KERNEL
136 checklist.append(OptCheck('BUG', 'y', 'defconfig', 'self_protection'))
137 checklist.append(OR(OptCheck('STRICT_KERNEL_RWX', 'y', 'defconfig', 'self_protection'), \
138 OptCheck('DEBUG_RODATA', 'y', 'defconfig', 'self_protection'))) # before v4.11
139 checklist.append(OR(OptCheck('STACKPROTECTOR_STRONG', 'y', 'defconfig', 'self_protection'), \
140 OptCheck('CC_STACKPROTECTOR_STRONG', 'y', 'defconfig', 'self_protection')))
141 checklist.append(OptCheck('SLUB_DEBUG', 'y', 'defconfig', 'self_protection'))
142 checklist.append(OR(OptCheck('STRICT_MODULE_RWX', 'y', 'defconfig', 'self_protection'), \
143 OptCheck('DEBUG_SET_MODULE_RONX', 'y', 'defconfig', 'self_protection'), \
144 modules_not_set)) # DEBUG_SET_MODULE_RONX was before v4.11
145 if debug_mode or arch == 'X86_64':
146 checklist.append(OptCheck('PAGE_TABLE_ISOLATION', 'y', 'defconfig', 'self_protection'))
147 checklist.append(OptCheck('RANDOMIZE_MEMORY', 'y', 'defconfig', 'self_protection'))
148 if debug_mode or arch == 'X86_64' or arch == 'X86_32':
149 checklist.append(OptCheck('RANDOMIZE_BASE', 'y', 'defconfig', 'self_protection'))
150 checklist.append(OptCheck('RETPOLINE', 'y', 'defconfig', 'self_protection'))
151 checklist.append(OptCheck('X86_SMAP', 'y', 'defconfig', 'self_protection'))
152 checklist.append(OptCheck('X86_INTEL_UMIP', 'y', 'defconfig', 'self_protection'))
153 checklist.append(OptCheck('SYN_COOKIES', 'y', 'defconfig', 'self_protection')) # another reason?
154 if debug_mode or arch == 'ARM64':
155 checklist.append(OptCheck('UNMAP_KERNEL_AT_EL0', 'y', 'defconfig', 'self_protection'))
156 if debug_mode or arch == 'X86_64' or arch == 'ARM64':
157 checklist.append(OptCheck('VMAP_STACK', 'y', 'defconfig', 'self_protection'))
158 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
159 checklist.append(OptCheck('THREAD_INFO_IN_TASK', 'y', 'defconfig', 'self_protection'))
160 if debug_mode or arch == 'ARM':
161 checklist.append(OptCheck('VMSPLIT_3G', 'y', 'defconfig', 'self_protection'))
162 checklist.append(OptCheck('CPU_SW_DOMAIN_PAN', 'y', 'defconfig', 'self_protection'))
163 if debug_mode or arch == 'ARM64' or arch == 'ARM':
164 checklist.append(OptCheck('REFCOUNT_FULL', 'y', 'defconfig', 'self_protection'))
166 checklist.append(OptCheck('BUG_ON_DATA_CORRUPTION', 'y', 'kspp', 'self_protection'))
167 checklist.append(OptCheck('DEBUG_WX', 'y', 'kspp', 'self_protection'))
168 checklist.append(OptCheck('SCHED_STACK_END_CHECK', 'y', 'kspp', 'self_protection'))
169 checklist.append(OptCheck('PAGE_POISONING', 'y', 'kspp', 'self_protection'))
170 checklist.append(OptCheck('SLAB_FREELIST_HARDENED', 'y', 'kspp', 'self_protection'))
171 checklist.append(OptCheck('SLAB_FREELIST_RANDOM', 'y', 'kspp', 'self_protection'))
172 checklist.append(OptCheck('HARDENED_USERCOPY', 'y', 'kspp', 'self_protection'))
173 checklist.append(OptCheck('HARDENED_USERCOPY_FALLBACK', 'is not set', 'kspp', 'self_protection'))
174 checklist.append(OptCheck('FORTIFY_SOURCE', 'y', 'kspp', 'self_protection'))
175 checklist.append(OptCheck('GCC_PLUGINS', 'y', 'kspp', 'self_protection'))
176 checklist.append(OptCheck('GCC_PLUGIN_RANDSTRUCT', 'y', 'kspp', 'self_protection'))
177 checklist.append(OptCheck('GCC_PLUGIN_STRUCTLEAK', 'y', 'kspp', 'self_protection'))
178 checklist.append(OptCheck('GCC_PLUGIN_STRUCTLEAK_BYREF_ALL', 'y', 'kspp', 'self_protection'))
179 checklist.append(OptCheck('GCC_PLUGIN_LATENT_ENTROPY', 'y', 'kspp', 'self_protection'))
180 checklist.append(OptCheck('DEBUG_LIST', 'y', 'kspp', 'self_protection'))
181 checklist.append(OptCheck('DEBUG_SG', 'y', 'kspp', 'self_protection'))
182 checklist.append(OptCheck('DEBUG_CREDENTIALS', 'y', 'kspp', 'self_protection'))
183 checklist.append(OptCheck('DEBUG_NOTIFIERS', 'y', 'kspp', 'self_protection'))
184 checklist.append(OR(OptCheck('MODULE_SIG', 'y', 'kspp', 'self_protection'), \
186 checklist.append(OR(OptCheck('MODULE_SIG_ALL', 'y', 'kspp', 'self_protection'), \
188 checklist.append(OR(OptCheck('MODULE_SIG_SHA512', 'y', 'kspp', 'self_protection'), \
190 checklist.append(OR(OptCheck('MODULE_SIG_FORCE', 'y', 'kspp', 'self_protection'), \
191 modules_not_set)) # refers to LOCK_DOWN_KERNEL
192 if debug_mode or arch == 'X86_64' or arch == 'X86_32':
193 checklist.append(OptCheck('DEFAULT_MMAP_MIN_ADDR', '65536', 'kspp', 'self_protection'))
194 checklist.append(OptCheck('REFCOUNT_FULL', 'y', 'kspp', 'self_protection'))
195 if debug_mode or arch == 'X86_32':
196 checklist.append(OptCheck('HIGHMEM64G', 'y', 'kspp', 'self_protection'))
197 checklist.append(OptCheck('X86_PAE', 'y', 'kspp', 'self_protection'))
198 if debug_mode or arch == 'ARM64':
199 checklist.append(OptCheck('ARM64_SW_TTBR0_PAN', 'y', 'kspp', 'self_protection'))
200 checklist.append(OptCheck('RANDOMIZE_BASE', 'y', 'kspp', 'self_protection'))
201 if debug_mode or arch == 'ARM64' or arch == 'ARM':
202 checklist.append(OptCheck('SYN_COOKIES', 'y', 'kspp', 'self_protection')) # another reason?
203 checklist.append(OptCheck('DEFAULT_MMAP_MIN_ADDR', '32768', 'kspp', 'self_protection'))
205 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
206 checklist.append(OptCheck('GCC_PLUGIN_STACKLEAK', 'y', 'my', 'self_protection'))
207 checklist.append(OptCheck('LOCK_DOWN_KERNEL', 'y', 'my', 'self_protection')) # remember about LOCK_DOWN_MANDATORY
208 checklist.append(OptCheck('SLUB_DEBUG_ON', 'y', 'my', 'self_protection'))
209 checklist.append(OptCheck('SECURITY_DMESG_RESTRICT', 'y', 'my', 'self_protection'))
210 checklist.append(OptCheck('STATIC_USERMODEHELPER', 'y', 'my', 'self_protection')) # breaks systemd?
211 checklist.append(OptCheck('SECURITY_LOADPIN', 'y', 'my', 'self_protection'))
212 checklist.append(OptCheck('PAGE_POISONING_NO_SANITY', 'is not set', 'my', 'self_protection'))
213 checklist.append(OptCheck('PAGE_POISONING_ZERO', 'is not set', 'my', 'self_protection'))
214 checklist.append(OptCheck('SLAB_MERGE_DEFAULT', 'is not set', 'my', 'self_protection')) # slab_nomerge
215 if debug_mode or arch == 'X86_32':
216 checklist.append(OptCheck('PAGE_TABLE_ISOLATION', 'y', 'my', 'self_protection'))
218 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
219 checklist.append(OptCheck('SECURITY', 'y', 'defconfig', 'security_policy'))
220 if debug_mode or arch == 'ARM':
221 checklist.append(OptCheck('SECURITY', 'y', 'kspp', 'security_policy'))
222 checklist.append(OptCheck('SECURITY_YAMA', 'y', 'kspp', 'security_policy'))
223 checklist.append(OptCheck('SECURITY_SELINUX_DISABLE', 'is not set', 'kspp', 'security_policy'))
225 checklist.append(OptCheck('SECCOMP', 'y', 'defconfig', 'cut_attack_surface'))
226 checklist.append(OptCheck('SECCOMP_FILTER', 'y', 'defconfig', 'cut_attack_surface'))
227 if debug_mode or arch == 'X86_64' or arch == 'ARM64' or arch == 'X86_32':
228 checklist.append(OR(OptCheck('STRICT_DEVMEM', 'y', 'defconfig', 'cut_attack_surface'), \
229 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
231 checklist.append(OR(OptCheck('IO_STRICT_DEVMEM', 'y', 'kspp', 'cut_attack_surface'), \
232 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
233 if debug_mode or arch == 'ARM':
234 checklist.append(OR(OptCheck('STRICT_DEVMEM', 'y', 'kspp', 'cut_attack_surface'), \
235 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
236 checklist.append(OptCheck('ACPI_CUSTOM_METHOD', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
237 checklist.append(OptCheck('COMPAT_BRK', 'is not set', 'kspp', 'cut_attack_surface'))
238 checklist.append(OptCheck('DEVKMEM', 'is not set', 'kspp', 'cut_attack_surface'))
239 checklist.append(OptCheck('COMPAT_VDSO', 'is not set', 'kspp', 'cut_attack_surface'))
240 checklist.append(OptCheck('BINFMT_MISC', 'is not set', 'kspp', 'cut_attack_surface'))
241 checklist.append(OptCheck('INET_DIAG', 'is not set', 'kspp', 'cut_attack_surface'))
242 checklist.append(OptCheck('KEXEC', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
243 checklist.append(OptCheck('PROC_KCORE', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
244 checklist.append(OptCheck('LEGACY_PTYS', 'is not set', 'kspp', 'cut_attack_surface'))
245 checklist.append(OptCheck('HIBERNATION', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
246 if debug_mode or arch == 'X86_64':
247 checklist.append(OptCheck('LEGACY_VSYSCALL_NONE', 'y', 'kspp', 'cut_attack_surface')) # 'vsyscall=none'
248 checklist.append(OptCheck('IA32_EMULATION', 'is not set', 'kspp', 'cut_attack_surface'))
249 checklist.append(OptCheck('X86_X32', 'is not set', 'kspp', 'cut_attack_surface'))
250 checklist.append(OptCheck('MODIFY_LDT_SYSCALL', 'is not set', 'kspp', 'cut_attack_surface'))
251 if debug_mode or arch == 'ARM':
252 checklist.append(OptCheck('OABI_COMPAT', 'is not set', 'kspp', 'cut_attack_surface'))
254 checklist.append(OptCheck('X86_PTDUMP', 'is not set', 'grsecurity', 'cut_attack_surface'))
255 checklist.append(OptCheck('ZSMALLOC_STAT', 'is not set', 'grsecurity', 'cut_attack_surface'))
256 checklist.append(OptCheck('PAGE_OWNER', 'is not set', 'grsecurity', 'cut_attack_surface'))
257 checklist.append(OptCheck('DEBUG_KMEMLEAK', 'is not set', 'grsecurity', 'cut_attack_surface'))
258 checklist.append(OptCheck('BINFMT_AOUT', 'is not set', 'grsecurity', 'cut_attack_surface'))
259 checklist.append(OptCheck('KPROBES', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
260 checklist.append(OptCheck('UPROBES', 'is not set', 'grsecurity', 'cut_attack_surface'))
261 checklist.append(OptCheck('GENERIC_TRACER', 'is not set', 'grsecurity', 'cut_attack_surface'))
262 checklist.append(OptCheck('PROC_VMCORE', 'is not set', 'grsecurity', 'cut_attack_surface'))
263 checklist.append(OptCheck('PROC_PAGE_MONITOR', 'is not set', 'grsecurity', 'cut_attack_surface'))
264 checklist.append(OptCheck('USELIB', 'is not set', 'grsecurity', 'cut_attack_surface'))
265 checklist.append(OptCheck('CHECKPOINT_RESTORE', 'is not set', 'grsecurity', 'cut_attack_surface'))
266 checklist.append(OptCheck('USERFAULTFD', 'is not set', 'grsecurity', 'cut_attack_surface'))
267 checklist.append(OptCheck('HWPOISON_INJECT', 'is not set', 'grsecurity', 'cut_attack_surface'))
268 checklist.append(OptCheck('MEM_SOFT_DIRTY', 'is not set', 'grsecurity', 'cut_attack_surface'))
269 checklist.append(OptCheck('DEVPORT', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
270 checklist.append(OptCheck('DEBUG_FS', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
271 checklist.append(OptCheck('NOTIFIER_ERROR_INJECTION','is not set', 'grsecurity', 'cut_attack_surface'))
273 checklist.append(OptCheck('ACPI_TABLE_UPGRADE', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
274 checklist.append(OptCheck('ACPI_APEI_EINJ', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
275 checklist.append(OptCheck('PROFILING', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
276 checklist.append(OptCheck('BPF_SYSCALL', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
277 checklist.append(OptCheck('MMIOTRACE_TEST', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
279 checklist.append(OptCheck('MMIOTRACE', 'is not set', 'my', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL (permissive)
280 checklist.append(OptCheck('KEXEC_FILE', 'is not set', 'my', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL (permissive)
281 checklist.append(OptCheck('LIVEPATCH', 'is not set', 'my', 'cut_attack_surface'))
282 checklist.append(OptCheck('USER_NS', 'is not set', 'my', 'cut_attack_surface')) # user.max_user_namespaces=0
283 checklist.append(OptCheck('IP_DCCP', 'is not set', 'my', 'cut_attack_surface'))
284 checklist.append(OptCheck('IP_SCTP', 'is not set', 'my', 'cut_attack_surface'))
285 checklist.append(OptCheck('FTRACE', 'is not set', 'my', 'cut_attack_surface'))
286 checklist.append(OptCheck('BPF_JIT', 'is not set', 'my', 'cut_attack_surface'))
287 if debug_mode or arch == 'X86_32':
288 checklist.append(OptCheck('MODIFY_LDT_SYSCALL', 'is not set', 'my', 'cut_attack_surface'))
290 if debug_mode or arch == 'X86_64' or arch == 'ARM64':
291 checklist.append(OptCheck('ARCH_MMAP_RND_BITS', '32', 'my', 'userspace_protection'))
292 if debug_mode or arch == 'X86_32' or arch == 'ARM':
293 checklist.append(OptCheck('ARCH_MMAP_RND_BITS', '16', 'my', 'userspace_protection'))
295 # checklist.append(OptCheck('LKDTM', 'm', 'my', 'feature_test'))
298 def print_checklist(arch):
299 print('[+] Printing kernel hardening preferences for {}...'.format(arch))
300 print(' {:<39}|{:^13}|{:^10}|{:^20}'.format(
301 'option name', 'desired val', 'decision', 'reason'))
302 print(' ' + '=' * 86)
303 for opt in checklist:
304 print(' CONFIG_{:<32}|{:^13}|{:^10}|{:^20}'.format(
305 opt.name, opt.expected, opt.decision, opt.reason))
309 def print_check_results():
310 print(' {:<39}|{:^13}|{:^10}|{:^20}||{:^28}'.format(
311 'option name', 'desired val', 'decision', 'reason', 'check result'))
312 print(' ' + '=' * 115)
313 for opt in checklist:
314 print(' CONFIG_{:<32}|{:^13}|{:^10}|{:^20}||{:^28}'.format(
315 opt.name, opt.expected, opt.decision, opt.reason, opt.result))
319 def get_option_state(options, name):
320 return options.get(name, None)
323 def perform_checks(parsed_options):
324 for opt in checklist:
325 if hasattr(opt, 'opts'):
327 o.state = get_option_state(parsed_options, o.name)
329 opt.state = get_option_state(parsed_options, opt.name)
333 def check_config_file(fname):
334 with open(fname, 'r') as f:
335 parsed_options = OrderedDict()
336 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
337 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
339 print('[+] Checking "{}" against hardening preferences...'.format(fname))
340 for line in f.readlines():
345 if opt_is_on.match(line):
346 option, value = line[7:].split('=', 1)
347 elif opt_is_off.match(line):
348 option, value = line[9:].split(' ', 1)
349 if value != 'is not set':
350 sys.exit('[!] ERROR: bad disabled config option "{}"'.format(line))
352 if option in parsed_options:
353 sys.exit('[!] ERROR: config option "{}" exists multiple times'.format(line))
355 if option is not None:
356 parsed_options[option] = value
358 perform_checks(parsed_options)
361 known_options = [opt.name for opt in checklist]
362 for option, value in parsed_options.items():
363 if option not in known_options:
364 print("DEBUG: dunno about option {} ({})".format(option, value))
366 print_check_results()
369 if __name__ == '__main__':
370 parser = ArgumentParser(description='Checks the hardening options in the Linux kernel config')
371 parser.add_argument('-p', '--print', choices=supported_archs,
372 help='print hardening preferences for selected architecture')
373 parser.add_argument('-c', '--config',
374 help='check the config_file against these preferences')
375 parser.add_argument('--debug', action='store_true',
376 help='enable internal debug mode')
377 args = parser.parse_args()
383 arch, msg = detect_arch(args.config)
385 sys.exit('[!] ERROR: {}'.format(msg))
387 print('[+] Detected architecture: {}'.format(arch))
389 construct_checklist(arch)
390 check_config_file(args.config)
391 error_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
395 print('[+] config check is PASSED')
398 sys.exit('[-] config check is NOT PASSED: {} errors'.format(error_count))
402 construct_checklist(arch)
403 print_checklist(arch)