3 # This tool helps me to check Linux kernel options against
4 # my security hardening preferences for X86_64, ARM64, X86_32, and ARM.
5 # 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.
11 # pylint: disable=missing-module-docstring,missing-class-docstring,missing-function-docstring
12 # pylint: disable=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
24 def detect_arch(fname, archs):
25 with open(fname, 'r', encoding='utf-8') as f:
26 arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
28 for line in f.readlines():
29 if arch_pattern.match(line):
30 option, _ = line[7:].split('=', 1)
35 return None, 'more than one supported architecture is detected'
37 return None, 'failed to detect architecture'
41 def detect_kernel_version(fname):
42 with open(fname, 'r', encoding='utf-8') as f:
43 ver_pattern = re.compile("# Linux/.* Kernel Configuration")
44 for line in f.readlines():
45 if ver_pattern.match(line):
49 ver_numbers = ver_str.split('.')
50 if len(ver_numbers) < 3 or not ver_numbers[0].isdigit() or not ver_numbers[1].isdigit():
51 msg = 'failed to parse the version "' + ver_str + '"'
53 return (int(ver_numbers[0]), int(ver_numbers[1])), None
54 return None, 'no kernel version detected'
57 def detect_compiler(fname):
60 with open(fname, 'r', encoding='utf-8') as f:
61 gcc_version_pattern = re.compile("CONFIG_GCC_VERSION=[0-9]*")
62 clang_version_pattern = re.compile("CONFIG_CLANG_VERSION=[0-9]*")
63 for line in f.readlines():
64 if gcc_version_pattern.match(line):
65 gcc_version = line[19:-1]
66 if clang_version_pattern.match(line):
67 clang_version = line[21:-1]
68 if not gcc_version or not clang_version:
69 return None, 'no CONFIG_GCC_VERSION or CONFIG_CLANG_VERSION'
70 if gcc_version == '0' and clang_version != '0':
71 return 'CLANG ' + clang_version, 'OK'
72 if gcc_version != '0' and clang_version == '0':
73 return 'GCC ' + gcc_version, 'OK'
74 sys.exit(f'[!] ERROR: invalid GCC_VERSION and CLANG_VERSION: {gcc_version} {clang_version}')
77 def print_unknown_options(checklist, parsed_options):
81 if o1.type != 'complex':
82 known_options.append(o1.name)
85 if o2.type != 'complex':
86 if hasattr(o2, 'name'):
87 known_options.append(o2.name)
90 assert(o3.type != 'complex'), \
91 f'unexpected ComplexOptCheck inside {o2.name}'
92 if hasattr(o3, 'name'):
93 known_options.append(o3.name)
95 for option, value in parsed_options.items():
96 if option not in known_options:
97 print(f'[?] No check for option {option} ({value})')
100 def print_checklist(mode, checklist, with_results):
104 output.append(o.json_dump(with_results))
105 print(json.dumps(output))
112 print('=' * sep_line_len)
113 print(f"{'option name':^40}|{'type':^7}|{'desired val':^12}|{'decision':^10}|{'reason':^18}", end='')
115 print('| check result', end='')
117 print('=' * sep_line_len)
120 for opt in checklist:
122 if mode == 'show_ok':
123 if not opt.result.startswith('OK'):
125 if mode == 'show_fail':
126 if not opt.result.startswith('FAIL'):
128 opt.table_print(mode, with_results)
130 if mode == 'verbose':
131 print('-' * sep_line_len)
136 fail_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
138 ok_count = len(list(filter(lambda opt: opt.result.startswith('OK'), checklist)))
140 if mode == 'show_ok':
141 fail_suppressed = ' (suppressed in output)'
142 if mode == 'show_fail':
143 ok_suppressed = ' (suppressed in output)'
145 print(f'[+] Config check is finished: \'OK\' - {ok_count}{ok_suppressed} / \'FAIL\' - {fail_count}{fail_suppressed}')
148 def parse_kconfig_file(parsed_options, fname):
149 with open(fname, 'r', encoding='utf-8') as f:
150 opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
151 opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
153 for line in f.readlines():
158 if opt_is_on.match(line):
159 option, value = line.split('=', 1)
160 if value == 'is not set':
161 sys.exit(f'[!] ERROR: bad enabled kconfig option "{line}"')
162 elif opt_is_off.match(line):
163 option, value = line[2:].split(' ', 1)
164 if value != 'is not set':
165 sys.exit(f'[!] ERROR: bad disabled kconfig option "{line}"')
167 if option in parsed_options:
168 sys.exit(f'[!] ERROR: kconfig option "{line}" exists multiple times')
171 parsed_options[option] = value
174 def parse_cmdline_file(parsed_options, fname):
175 with open(fname, 'r', encoding='utf-8') as f:
181 sys.exit(f'[!] ERROR: more than one line in "{fname}"')
185 name, value = opt.split('=', 1)
188 value = '' # '' is not None
189 value = normalize_cmdline_options(name, value)
190 parsed_options[name] = value
196 # - reporting about unknown kernel options in the kconfig
197 # - verbose printing of ComplexOptCheck items
198 # * json mode for printing the results in JSON format
199 report_modes = ['verbose', 'json', 'show_ok', 'show_fail']
200 supported_archs = ['X86_64', 'X86_32', 'ARM64', 'ARM']
201 parser = ArgumentParser(prog='kconfig-hardened-check',
202 description='A tool for checking the security hardening options of the Linux kernel')
203 parser.add_argument('--version', action='version', version='%(prog)s ' + __version__)
204 parser.add_argument('-p', '--print', choices=supported_archs,
205 help='print security hardening preferences for the selected architecture')
206 parser.add_argument('-c', '--config',
207 help='check the kernel kconfig file against these preferences')
208 parser.add_argument('-l', '--cmdline',
209 help='check the kernel cmdline file against these preferences')
210 parser.add_argument('-m', '--mode', choices=report_modes,
211 help='choose the report mode')
212 args = parser.parse_args()
218 print(f'[+] Special report mode: {mode}')
220 config_checklist = []
224 sys.exit('[!] ERROR: --config and --print can\'t be used together')
227 print(f'[+] Kconfig file to check: {args.config}')
229 print(f'[+] Kernel cmdline file to check: {args.cmdline}')
231 arch, msg = detect_arch(args.config, supported_archs)
233 sys.exit(f'[!] ERROR: {msg}')
235 print(f'[+] Detected architecture: {arch}')
237 kernel_version, msg = detect_kernel_version(args.config)
238 if not kernel_version:
239 sys.exit(f'[!] ERROR: {msg}')
241 print(f'[+] Detected kernel version: {kernel_version[0]}.{kernel_version[1]}')
243 compiler, msg = detect_compiler(args.config)
246 print(f'[+] Detected compiler: {compiler}')
248 print(f'[-] Can\'t detect the compiler: {msg}')
250 # add relevant kconfig checks to the checklist
251 add_kconfig_checks(config_checklist, arch)
254 # add relevant cmdline checks to the checklist
255 add_cmdline_checks(config_checklist, arch)
257 # populate the checklist with the parsed kconfig data
258 parsed_kconfig_options = OrderedDict()
259 parse_kconfig_file(parsed_kconfig_options, args.config)
260 populate_with_data(config_checklist, parsed_kconfig_options, 'kconfig')
261 populate_with_data(config_checklist, kernel_version, 'version')
264 # populate the checklist with the parsed kconfig data
265 parsed_cmdline_options = OrderedDict()
266 parse_cmdline_file(parsed_cmdline_options, args.cmdline)
267 populate_with_data(config_checklist, parsed_cmdline_options, 'cmdline')
269 # now everything is ready, perform the checks
270 perform_checks(config_checklist)
272 if mode == 'verbose':
273 # print the parsed options without the checks (for debugging)
274 all_parsed_options = parsed_kconfig_options # assignment does not copy
276 all_parsed_options.update(parsed_cmdline_options)
277 print_unknown_options(config_checklist, all_parsed_options)
279 # finally print the results
280 print_checklist(mode, config_checklist, True)
284 sys.exit('[!] ERROR: checking cmdline doesn\'t work without checking kconfig')
287 if mode in ('show_ok', 'show_fail'):
288 sys.exit(f'[!] ERROR: wrong mode "{mode}" for --print')
290 add_kconfig_checks(config_checklist, arch)
291 add_cmdline_checks(config_checklist, arch)
293 print(f'[+] Printing kernel security hardening preferences for {arch}...')
294 print_checklist(mode, config_checklist, False)