4 This tool is for checking the security hardening options of the Linux kernel.
6 Author: Alexander Popov <alex.popov@linux.com>
8 This module performs input/output.
11 # pylint: disable=missing-function-docstring,line-too-long,invalid-name,too-many-branches,too-many-statements
15 from argparse import ArgumentParser
16 from collections import OrderedDict
19 from .__about__ import __version__
20 from .checks import add_kconfig_checks, add_cmdline_checks, normalize_cmdline_options
21 from .engine import populate_with_data, perform_checks, override_expected_value
24 def _open(file: str, *args, **kwargs):
26 if file.endswith(".gz"):
27 open_method = gzip.open
29 return open_method(file, *args, **kwargs)
32 def detect_arch(fname, archs):
33 with _open(fname, 'rt', encoding='utf-8') as f:
34 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
36 for line in f.readlines():
37 if arch_pattern.match(line):
38 option, _ = line[7:].split('=', 1)
43 return None, 'more than one supported microarchitecture is detected'
45 return None, 'failed to detect microarchitecture'
49 def detect_kernel_version(fname):
50 with _open(fname, 'rt', encoding='utf-8') as f:
51 ver_pattern = re.compile("# Linux/.* Kernel Configuration")
52 for line in f.readlines():
53 if ver_pattern.match(line):
57 ver_numbers = ver_str.split('.')
58 if len(ver_numbers) < 3 or not ver_numbers[0].isdigit() or not ver_numbers[1].isdigit():
59 msg = f'failed to parse the version "{ver_str}"'
61 return (int(ver_numbers[0]), int(ver_numbers[1])), None
62 return None, 'no kernel version detected'
65 def detect_compiler(fname):
68 with _open(fname, 'rt', encoding='utf-8') as f:
69 gcc_version_pattern = re.compile("CONFIG_GCC_VERSION=[0-9]*")
70 clang_version_pattern = re.compile("CONFIG_CLANG_VERSION=[0-9]*")
71 for line in f.readlines():
72 if gcc_version_pattern.match(line):
73 gcc_version = line[19:-1]
74 if clang_version_pattern.match(line):
75 clang_version = line[21:-1]
76 if gcc_version is None or clang_version is None:
77 return None, 'no CONFIG_GCC_VERSION or CONFIG_CLANG_VERSION'
78 if gcc_version == '0' and clang_version != '0':
79 return 'CLANG ' + clang_version, 'OK'
80 if gcc_version != '0' and clang_version == '0':
81 return 'GCC ' + gcc_version, 'OK'
82 sys.exit(f'[!] ERROR: invalid GCC_VERSION and CLANG_VERSION: {gcc_version} {clang_version}')
85 def print_unknown_options(checklist, parsed_options):
89 if o1.type != 'complex':
90 known_options.append(o1.name)
93 if o2.type != 'complex':
94 if hasattr(o2, 'name'):
95 known_options.append(o2.name)
98 assert(o3.type != 'complex'), \
99 f'unexpected ComplexOptCheck inside {o2.name}'
100 if hasattr(o3, 'name'):
101 known_options.append(o3.name)
103 for option, value in parsed_options.items():
104 if option not in known_options:
105 print(f'[?] No check for option {option} ({value})')
108 def print_checklist(mode, checklist, with_results):
111 for opt in checklist:
112 output.append(opt.json_dump(with_results))
113 print(json.dumps(output))
120 print('=' * sep_line_len)
121 print(f'{"option name":^40}|{"type":^7}|{"desired val":^12}|{"decision":^10}|{"reason":^18}', end='')
123 print('| check result', end='')
125 print('=' * sep_line_len)
128 for opt in checklist:
130 if mode == 'show_ok':
131 if not opt.result.startswith('OK'):
133 if mode == 'show_fail':
134 if not opt.result.startswith('FAIL'):
136 opt.table_print(mode, with_results)
138 if mode == 'verbose':
139 print('-' * sep_line_len)
144 fail_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
146 ok_count = len(list(filter(lambda opt: opt.result.startswith('OK'), checklist)))
148 if mode == 'show_ok':
149 fail_suppressed = ' (suppressed in output)'
150 if mode == 'show_fail':
151 ok_suppressed = ' (suppressed in output)'
152 print(f'[+] Config check is finished: \'OK\' - {ok_count}{ok_suppressed} / \'FAIL\' - {fail_count}{fail_suppressed}')
155 def parse_kconfig_file(parsed_options, fname):
156 with _open(fname, 'rt', encoding='utf-8') as f:
157 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
158 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
160 for line in f.readlines():
165 if opt_is_on.match(line):
166 option, value = line.split('=', 1)
167 if value == 'is not set':
168 sys.exit(f'[!] ERROR: bad enabled Kconfig option "{line}"')
169 elif opt_is_off.match(line):
170 option, value = line[2:].split(' ', 1)
171 if value != 'is not set':
172 sys.exit(f'[!] ERROR: bad disabled Kconfig option "{line}"')
174 if option in parsed_options:
175 sys.exit(f'[!] ERROR: Kconfig option "{line}" exists multiple times')
178 parsed_options[option] = value
181 def parse_cmdline_file(parsed_options, fname):
182 with open(fname, 'r', encoding='utf-8') as f:
188 sys.exit(f'[!] ERROR: more than one line in "{fname}"')
192 name, value = opt.split('=', 1)
195 value = '' # '' is not None
196 value = normalize_cmdline_options(name, value)
197 parsed_options[name] = value
203 # - reporting about unknown kernel options in the Kconfig
204 # - verbose printing of ComplexOptCheck items
205 # * json mode for printing the results in JSON format
206 report_modes = ['verbose', 'json', 'show_ok', 'show_fail']
207 supported_archs = ['X86_64', 'X86_32', 'ARM64', 'ARM']
208 parser = ArgumentParser(prog='kconfig-hardened-check',
209 description='A tool for checking the security hardening options of the Linux kernel')
210 parser.add_argument('--version', action='version', version='%(prog)s ' + __version__)
211 parser.add_argument('-m', '--mode', choices=report_modes,
212 help='choose the report mode')
213 parser.add_argument('-c', '--config',
214 help='check the security hardening options in the kernel Kconfig file (also supports *.gz files)')
215 parser.add_argument('-l', '--cmdline',
216 help='check the security hardening options in the kernel cmdline file (contents of /proc/cmdline)')
217 parser.add_argument('-p', '--print', choices=supported_archs,
218 help='print the security hardening recommendations for the selected microarchitecture')
219 parser.add_argument('-g', '--generate', choices=supported_archs,
220 help='generate a Kconfig fragment with the security hardening options for the selected microarchitecture')
221 args = parser.parse_args()
227 print(f'[+] Special report mode: {mode}')
229 config_checklist = []
233 sys.exit('[!] ERROR: --config and --print can\'t be used together')
236 sys.exit('[!] ERROR: --config and --generate can\'t be used together')
239 print(f'[+] Kconfig file to check: {args.config}')
241 print(f'[+] Kernel cmdline file to check: {args.cmdline}')
243 arch, msg = detect_arch(args.config, supported_archs)
245 sys.exit(f'[!] ERROR: {msg}')
247 print(f'[+] Detected microarchitecture: {arch}')
249 kernel_version, msg = detect_kernel_version(args.config)
250 if kernel_version is None:
251 sys.exit(f'[!] ERROR: {msg}')
253 print(f'[+] Detected kernel version: {kernel_version[0]}.{kernel_version[1]}')
255 compiler, msg = detect_compiler(args.config)
258 print(f'[+] Detected compiler: {compiler}')
260 print(f'[-] Can\'t detect the compiler: {msg}')
262 # add relevant Kconfig checks to the checklist
263 add_kconfig_checks(config_checklist, arch)
266 # add relevant cmdline checks to the checklist
267 add_cmdline_checks(config_checklist, arch)
269 # populate the checklist with the parsed Kconfig data
270 parsed_kconfig_options = OrderedDict()
271 parse_kconfig_file(parsed_kconfig_options, args.config)
272 populate_with_data(config_checklist, parsed_kconfig_options, 'kconfig')
274 # populate the checklist with the kernel version data
275 populate_with_data(config_checklist, kernel_version, 'version')
278 # populate the checklist with the parsed cmdline data
279 parsed_cmdline_options = OrderedDict()
280 parse_cmdline_file(parsed_cmdline_options, args.cmdline)
281 populate_with_data(config_checklist, parsed_cmdline_options, 'cmdline')
283 # hackish refinement of the CONFIG_ARCH_MMAP_RND_BITS check
284 mmap_rnd_bits_max = parsed_kconfig_options.get('CONFIG_ARCH_MMAP_RND_BITS_MAX', None)
285 if mmap_rnd_bits_max:
286 override_expected_value(config_checklist, 'CONFIG_ARCH_MMAP_RND_BITS', mmap_rnd_bits_max)
288 # now everything is ready, perform the checks
289 perform_checks(config_checklist)
291 if mode == 'verbose':
292 # print the parsed options without the checks (for debugging)
293 all_parsed_options = parsed_kconfig_options # assignment does not copy
295 all_parsed_options.update(parsed_cmdline_options)
296 print_unknown_options(config_checklist, all_parsed_options)
298 # finally print the results
299 print_checklist(mode, config_checklist, True)
303 sys.exit('[!] ERROR: checking cmdline doesn\'t work without checking Kconfig')
306 assert(args.config is None and args.cmdline is None), 'unexpected args'
307 if mode and mode not in ('verbose', 'json'):
308 sys.exit(f'[!] ERROR: wrong mode "{mode}" for --print')
310 add_kconfig_checks(config_checklist, arch)
311 add_cmdline_checks(config_checklist, arch)
313 print(f'[+] Printing kernel security hardening options for {arch}...')
314 print_checklist(mode, config_checklist, False)
318 assert(args.config is None and args.cmdline is None), 'unexpected args'
320 sys.exit(f'[!] ERROR: wrong mode "{mode}" for --generate')
322 add_kconfig_checks(config_checklist, arch)
323 print(f'CONFIG_{arch}=y') # the Kconfig fragment should describe the microarchitecture
324 for opt in config_checklist:
325 if opt.name == 'CONFIG_ARCH_MMAP_RND_BITS':
326 continue # don't add CONFIG_ARCH_MMAP_RND_BITS because its value needs refinement
327 if opt.expected == 'is not set':
328 print(f'# {opt.name} is not set')
330 print(f'{opt.name}={opt.expected}')