4 # This script helps me to check the Linux kernel Kconfig option list
5 # against my hardening preferences for x86_64. Let the computers do their job!
7 # Author: Alexander Popov <alex.popov@linux.com>
9 # Please don't cry if my Python code looks like C.
12 # N.B Hardening command line parameters:
17 # kernel.kptr_restrict=1
22 # spec_store_bypass_disable=on
26 # N.B. Hardening sysctl's:
27 # net.core.bpf_jit_harden
30 # TODO: add hardening preferences for ARM
33 from argparse import ArgumentParser
34 from collections import OrderedDict
37 debug_mode = False # set it to True to print the unknown options from the config
39 supported_archs = [ 'X86_64', 'X86_32', 'ARM64' ]
45 def __init__(self, name, expected, decision, reason):
47 self.expected = expected
48 self.decision = decision
54 if self.expected == self.state:
56 elif self.state is None:
57 if self.expected == 'is not set':
58 self.result = 'OK: not found'
60 self.result = 'FAIL: not found'
62 self.result = 'FAIL: "' + self.state + '"'
64 if self.result.startswith('OK'):
65 return True, self.result
67 return False, self.result
70 return '{} = {}'.format(self.name, self.state)
74 def __init__(self, *opts):
78 # self.opts[0] is the option which this OR-check is about.
79 # Use case: OR(<X_is_hardened>, <X_is_disabled>)
83 return self.opts[0].name
87 return self.opts[0].expected
91 return self.opts[0].state
95 return self.opts[0].decision
99 return self.opts[0].reason
102 for i, opt in enumerate(self.opts):
103 result, msg = opt.check()
106 self.result = opt.result
108 self.result = 'CONFIG_{}: {} ("{}")'.format(opt.name, opt.result, opt.expected)
109 return True, self.result
110 self.result = self.opts[0].result
111 return False, self.result
114 def detect_arch(fname):
115 with open(fname, 'r') as f:
116 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
119 print('[+] Trying to detect architecture in "{}"...'.format(fname))
120 for line in f.readlines():
121 if arch_pattern.match(line):
122 option, value = line[7:].split('=', 1)
123 if option in supported_archs:
127 return None, 'more than one supported architecture is detected'
129 return None, 'failed to detect architecture'
134 def construct_checklist(arch):
135 modules_not_set = OptCheck('MODULES', 'is not set', 'kspp', 'cut_attack_surface')
136 devmem_not_set = OptCheck('DEVMEM', 'is not set', 'kspp', 'cut_attack_surface') # refers to LOCK_DOWN_KERNEL
138 checklist.append(OptCheck('BUG', 'y', 'defconfig', 'self_protection'))
139 checklist.append(OR(OptCheck('STRICT_KERNEL_RWX', 'y', 'defconfig', 'self_protection'), \
140 OptCheck('DEBUG_RODATA', 'y', 'defconfig', 'self_protection'))) # before v4.11
141 checklist.append(OR(OptCheck('STACKPROTECTOR_STRONG', 'y', 'defconfig', 'self_protection'), \
142 OptCheck('CC_STACKPROTECTOR_STRONG', 'y', 'defconfig', 'self_protection')))
143 checklist.append(OptCheck('THREAD_INFO_IN_TASK', 'y', 'defconfig', 'self_protection'))
144 checklist.append(OptCheck('SLUB_DEBUG', 'y', 'defconfig', 'self_protection'))
145 checklist.append(OR(OptCheck('STRICT_MODULE_RWX', 'y', 'defconfig', 'self_protection'), \
146 OptCheck('DEBUG_SET_MODULE_RONX', 'y', 'defconfig', 'self_protection'), \
147 modules_not_set)) # DEBUG_SET_MODULE_RONX was before v4.11
149 checklist.append(OptCheck('PAGE_TABLE_ISOLATION', 'y', 'defconfig', 'self_protection'))
150 checklist.append(OptCheck('RANDOMIZE_MEMORY', 'y', 'defconfig', 'self_protection'))
151 if arch == 'X86_64' or arch == 'X86_32':
152 checklist.append(OptCheck('RANDOMIZE_BASE', 'y', 'defconfig', 'self_protection'))
153 checklist.append(OptCheck('RETPOLINE', 'y', 'defconfig', 'self_protection'))
154 checklist.append(OptCheck('X86_SMAP', 'y', 'defconfig', 'self_protection'))
155 checklist.append(OptCheck('X86_INTEL_UMIP', 'y', 'defconfig', 'self_protection'))
156 checklist.append(OptCheck('SYN_COOKIES', 'y', 'defconfig', 'self_protection')) # another reason?
158 checklist.append(OptCheck('UNMAP_KERNEL_AT_EL0', 'y', 'defconfig', 'self_protection'))
159 checklist.append(OptCheck('REFCOUNT_FULL', 'y', 'defconfig', 'self_protection'))
160 if debug_mode or arch == 'X86_64' or arch == 'ARM64':
161 checklist.append(OptCheck('VMAP_STACK', 'y', 'defconfig', 'self_protection'))
163 checklist.append(OptCheck('BUG_ON_DATA_CORRUPTION', 'y', 'kspp', 'self_protection'))
164 checklist.append(OptCheck('DEBUG_WX', 'y', 'kspp', 'self_protection'))
165 checklist.append(OptCheck('SCHED_STACK_END_CHECK', 'y', 'kspp', 'self_protection'))
166 checklist.append(OptCheck('PAGE_POISONING', 'y', 'kspp', 'self_protection'))
167 checklist.append(OptCheck('SLAB_FREELIST_HARDENED', 'y', 'kspp', 'self_protection'))
168 checklist.append(OptCheck('SLAB_FREELIST_RANDOM', 'y', 'kspp', 'self_protection'))
169 checklist.append(OptCheck('HARDENED_USERCOPY', 'y', 'kspp', 'self_protection'))
170 checklist.append(OptCheck('HARDENED_USERCOPY_FALLBACK', 'is not set', 'kspp', 'self_protection'))
171 checklist.append(OptCheck('FORTIFY_SOURCE', 'y', 'kspp', 'self_protection'))
172 checklist.append(OptCheck('GCC_PLUGINS', 'y', 'kspp', 'self_protection'))
173 checklist.append(OptCheck('GCC_PLUGIN_RANDSTRUCT', 'y', 'kspp', 'self_protection'))
174 checklist.append(OptCheck('GCC_PLUGIN_STRUCTLEAK', 'y', 'kspp', 'self_protection'))
175 checklist.append(OptCheck('GCC_PLUGIN_STRUCTLEAK_BYREF_ALL', 'y', 'kspp', 'self_protection'))
176 checklist.append(OptCheck('GCC_PLUGIN_LATENT_ENTROPY', 'y', 'kspp', 'self_protection'))
177 checklist.append(OptCheck('DEBUG_LIST', 'y', 'kspp', 'self_protection'))
178 checklist.append(OptCheck('DEBUG_SG', 'y', 'kspp', 'self_protection'))
179 checklist.append(OptCheck('DEBUG_CREDENTIALS', 'y', 'kspp', 'self_protection'))
180 checklist.append(OptCheck('DEBUG_NOTIFIERS', 'y', 'kspp', 'self_protection'))
181 checklist.append(OR(OptCheck('MODULE_SIG', 'y', 'kspp', 'self_protection'), \
183 checklist.append(OR(OptCheck('MODULE_SIG_ALL', 'y', 'kspp', 'self_protection'), \
185 checklist.append(OR(OptCheck('MODULE_SIG_SHA512', 'y', 'kspp', 'self_protection'), \
187 checklist.append(OptCheck('MODULE_SIG_FORCE', 'y', 'kspp', 'self_protection')) # refers to LOCK_DOWN_KERNEL
188 if arch == 'X86_64' or arch == 'X86_32':
189 checklist.append(OptCheck('DEFAULT_MMAP_MIN_ADDR', '65536', 'kspp', 'self_protection'))
190 checklist.append(OptCheck('REFCOUNT_FULL', 'y', 'kspp', 'self_protection'))
192 checklist.append(OptCheck('HIGHMEM64G', 'y', 'kspp', 'self_protection'))
193 checklist.append(OptCheck('X86_PAE', 'y', 'kspp', 'self_protection'))
195 checklist.append(OptCheck('DEFAULT_MMAP_MIN_ADDR', '32768', 'kspp', 'self_protection'))
196 checklist.append(OptCheck('ARM64_SW_TTBR0_PAN', 'y', 'kspp', 'self_protection'))
197 checklist.append(OptCheck('RANDOMIZE_BASE', 'y', 'kspp', 'self_protection'))
198 checklist.append(OptCheck('SYN_COOKIES', 'y', 'kspp', 'self_protection')) # another reason?
200 checklist.append(OptCheck('GCC_PLUGIN_STACKLEAK', 'y', 'my', 'self_protection'))
201 checklist.append(OptCheck('LOCK_DOWN_KERNEL', 'y', 'my', 'self_protection')) # remember about LOCK_DOWN_MANDATORY
202 checklist.append(OptCheck('SLUB_DEBUG_ON', 'y', 'my', 'self_protection'))
203 checklist.append(OptCheck('SECURITY_DMESG_RESTRICT', 'y', 'my', 'self_protection'))
204 checklist.append(OptCheck('STATIC_USERMODEHELPER', 'y', 'my', 'self_protection')) # breaks systemd?
205 checklist.append(OptCheck('SECURITY_LOADPIN', 'y', 'my', 'self_protection'))
206 checklist.append(OptCheck('PAGE_POISONING_NO_SANITY', 'is not set', 'my', 'self_protection'))
207 checklist.append(OptCheck('PAGE_POISONING_ZERO', 'is not set', 'my', 'self_protection'))
208 checklist.append(OptCheck('SLAB_MERGE_DEFAULT', 'is not set', 'my', 'self_protection')) # slab_nomerge
210 checklist.append(OptCheck('PAGE_TABLE_ISOLATION', 'y', 'my', 'self_protection'))
212 checklist.append(OptCheck('SECURITY', 'y', 'defconfig', 'security_policy'))
213 checklist.append(OptCheck('SECURITY_YAMA', 'y', 'kspp', 'security_policy'))
214 checklist.append(OptCheck('SECURITY_SELINUX_DISABLE', 'is not set', 'kspp', 'security_policy'))
216 checklist.append(OptCheck('SECCOMP', 'y', 'defconfig', 'cut_attack_surface'))
217 checklist.append(OptCheck('SECCOMP_FILTER', 'y', 'defconfig', 'cut_attack_surface'))
218 checklist.append(OR(OptCheck('STRICT_DEVMEM', 'y', 'defconfig', 'cut_attack_surface'), \
219 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
221 checklist.append(OR(OptCheck('IO_STRICT_DEVMEM', 'y', 'kspp', 'cut_attack_surface'), \
222 devmem_not_set)) # refers to LOCK_DOWN_KERNEL
223 checklist.append(OptCheck('ACPI_CUSTOM_METHOD', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
224 checklist.append(OptCheck('COMPAT_BRK', 'is not set', 'kspp', 'cut_attack_surface'))
225 checklist.append(OptCheck('DEVKMEM', 'is not set', 'kspp', 'cut_attack_surface'))
226 checklist.append(OptCheck('COMPAT_VDSO', 'is not set', 'kspp', 'cut_attack_surface'))
227 checklist.append(OptCheck('BINFMT_MISC', 'is not set', 'kspp', 'cut_attack_surface'))
228 checklist.append(OptCheck('INET_DIAG', 'is not set', 'kspp', 'cut_attack_surface'))
229 checklist.append(OptCheck('KEXEC', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
230 checklist.append(OptCheck('PROC_KCORE', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
231 checklist.append(OptCheck('LEGACY_PTYS', 'is not set', 'kspp', 'cut_attack_surface'))
232 checklist.append(OptCheck('HIBERNATION', 'is not set', 'kspp', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
234 checklist.append(OptCheck('LEGACY_VSYSCALL_NONE', 'y', 'kspp', 'cut_attack_surface')) # 'vsyscall=none'
235 checklist.append(OptCheck('IA32_EMULATION', 'is not set', 'kspp', 'cut_attack_surface'))
236 checklist.append(OptCheck('X86_X32', 'is not set', 'kspp', 'cut_attack_surface'))
237 checklist.append(OptCheck('MODIFY_LDT_SYSCALL', 'is not set', 'kspp', 'cut_attack_surface'))
239 checklist.append(OptCheck('X86_PTDUMP', 'is not set', 'grsecurity', 'cut_attack_surface'))
240 checklist.append(OptCheck('ZSMALLOC_STAT', 'is not set', 'grsecurity', 'cut_attack_surface'))
241 checklist.append(OptCheck('PAGE_OWNER', 'is not set', 'grsecurity', 'cut_attack_surface'))
242 checklist.append(OptCheck('DEBUG_KMEMLEAK', 'is not set', 'grsecurity', 'cut_attack_surface'))
243 checklist.append(OptCheck('BINFMT_AOUT', 'is not set', 'grsecurity', 'cut_attack_surface'))
244 checklist.append(OptCheck('KPROBES', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
245 checklist.append(OptCheck('UPROBES', 'is not set', 'grsecurity', 'cut_attack_surface'))
246 checklist.append(OptCheck('GENERIC_TRACER', 'is not set', 'grsecurity', 'cut_attack_surface'))
247 checklist.append(OptCheck('PROC_VMCORE', 'is not set', 'grsecurity', 'cut_attack_surface'))
248 checklist.append(OptCheck('PROC_PAGE_MONITOR', 'is not set', 'grsecurity', 'cut_attack_surface'))
249 checklist.append(OptCheck('USELIB', 'is not set', 'grsecurity', 'cut_attack_surface'))
250 checklist.append(OptCheck('CHECKPOINT_RESTORE', 'is not set', 'grsecurity', 'cut_attack_surface'))
251 checklist.append(OptCheck('USERFAULTFD', 'is not set', 'grsecurity', 'cut_attack_surface'))
252 checklist.append(OptCheck('HWPOISON_INJECT', 'is not set', 'grsecurity', 'cut_attack_surface'))
253 checklist.append(OptCheck('MEM_SOFT_DIRTY', 'is not set', 'grsecurity', 'cut_attack_surface'))
254 checklist.append(OptCheck('DEVPORT', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
255 checklist.append(OptCheck('DEBUG_FS', 'is not set', 'grsecurity', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
256 checklist.append(OptCheck('NOTIFIER_ERROR_INJECTION','is not set', 'grsecurity', 'cut_attack_surface'))
258 checklist.append(OptCheck('ACPI_TABLE_UPGRADE', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
259 checklist.append(OptCheck('ACPI_APEI_EINJ', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
260 checklist.append(OptCheck('PROFILING', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
261 checklist.append(OptCheck('BPF_SYSCALL', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
262 checklist.append(OptCheck('MMIOTRACE_TEST', 'is not set', 'lockdown', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL
264 checklist.append(OptCheck('MMIOTRACE', 'is not set', 'my', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL (permissive)
265 checklist.append(OptCheck('KEXEC_FILE', 'is not set', 'my', 'cut_attack_surface')) # refers to LOCK_DOWN_KERNEL (permissive)
266 checklist.append(OptCheck('LIVEPATCH', 'is not set', 'my', 'cut_attack_surface'))
267 checklist.append(OptCheck('USER_NS', 'is not set', 'my', 'cut_attack_surface')) # user.max_user_namespaces=0
268 checklist.append(OptCheck('IP_DCCP', 'is not set', 'my', 'cut_attack_surface'))
269 checklist.append(OptCheck('IP_SCTP', 'is not set', 'my', 'cut_attack_surface'))
270 checklist.append(OptCheck('FTRACE', 'is not set', 'my', 'cut_attack_surface'))
271 checklist.append(OptCheck('BPF_JIT', 'is not set', 'my', 'cut_attack_surface'))
273 checklist.append(OptCheck('MODIFY_LDT_SYSCALL', 'is not set', 'my', 'cut_attack_surface'))
275 if arch == 'X86_64' or arch == 'ARM64':
276 checklist.append(OptCheck('ARCH_MMAP_RND_BITS', '32', 'my', 'userspace_protection'))
278 checklist.append(OptCheck('ARCH_MMAP_RND_BITS', '16', 'my', 'userspace_protection'))
280 # checklist.append(OptCheck('LKDTM', 'm', 'my', 'feature_test'))
283 def print_checklist(arch):
284 print('[+] Printing kernel hardening preferences for {}...'.format(arch))
285 print(' {:<39}|{:^13}|{:^10}|{:^20}'.format(
286 'option name', 'desired val', 'decision', 'reason'))
287 print(' ' + '=' * 86)
288 for opt in checklist:
289 print(' CONFIG_{:<32}|{:^13}|{:^10}|{:^20}'.format(
290 opt.name, opt.expected, opt.decision, opt.reason))
294 def print_check_results():
295 print(' {:<39}|{:^13}|{:^10}|{:^20}||{:^28}'.format(
296 'option name', 'desired val', 'decision', 'reason', 'check result'))
297 print(' ' + '=' * 115)
298 for opt in checklist:
299 print(' CONFIG_{:<32}|{:^13}|{:^10}|{:^20}||{:^28}'.format(
300 opt.name, opt.expected, opt.decision, opt.reason, opt.result))
304 def get_option_state(options, name):
305 return options.get(name, None)
308 def perform_checks(parsed_options):
309 for opt in checklist:
310 if hasattr(opt, 'opts'):
312 o.state = get_option_state(parsed_options, o.name)
314 opt.state = get_option_state(parsed_options, opt.name)
318 def check_config_file(fname):
319 with open(fname, 'r') as f:
320 parsed_options = OrderedDict()
321 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
322 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
324 print('[+] Checking "{}" against hardening preferences...'.format(fname))
325 for line in f.readlines():
330 if opt_is_on.match(line):
331 option, value = line[7:].split('=', 1)
332 elif opt_is_off.match(line):
333 option, value = line[9:].split(' ', 1)
334 if value != 'is not set':
335 sys.exit('[!] ERROR: bad disabled config option "{}"'.format(line))
337 if option in parsed_options:
338 sys.exit('[!] ERROR: config option "{}" exists multiple times'.format(line))
340 if option is not None:
341 parsed_options[option] = value
343 perform_checks(parsed_options)
346 known_options = [opt.name for opt in checklist]
347 for option, value in parsed_options.items():
348 if option not in known_options:
349 print("DEBUG: dunno about option {} ({})".format(option, value))
351 print_check_results()
354 if __name__ == '__main__':
355 parser = ArgumentParser(description='Checks the hardening options in the Linux kernel config')
356 parser.add_argument('-p', '--print', choices=supported_archs,
357 help='print hardening preferences for selected architecture')
358 parser.add_argument('-c', '--config',
359 help='check the config_file against these preferences')
360 parser.add_argument('--debug', action='store_true',
361 help='enable internal debug mode')
362 args = parser.parse_args()
368 arch, msg = detect_arch(args.config)
370 sys.exit('[!] ERROR: {}'.format(msg))
372 print('[+] Detected architecture: {}'.format(arch))
374 construct_checklist(arch)
375 check_config_file(args.config)
376 error_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
378 print('[+] config check is PASSED')
381 sys.exit('[-] config check is NOT PASSED: {} errors'.format(error_count))
385 construct_checklist(arch)
386 print_checklist(arch)