-#!/usr/bin/python3
+#!/usr/bin/env python3
"""
This tool is for checking the security hardening options of the Linux kernel.
This module performs input/output.
"""
-# pylint: disable=missing-function-docstring,line-too-long,invalid-name,too-many-branches,too-many-statements
+# pylint: disable=missing-function-docstring,line-too-long,too-many-branches,too-many-statements
import gzip
import sys
from argparse import ArgumentParser
-from collections import OrderedDict
+from typing import List, Tuple, Dict, TextIO
import re
import json
-from .__about__ import __version__
from .checks import add_kconfig_checks, add_cmdline_checks, normalize_cmdline_options, add_sysctl_checks
-from .engine import populate_with_data, perform_checks, override_expected_value
+from .engine import StrOrNone, TupleOrNone, ChecklistObjType
+from .engine import print_unknown_options, populate_with_data, perform_checks, override_expected_value
-def _open(file: str, *args, **kwargs):
- open_method = open
- if file.endswith(".gz"):
- open_method = gzip.open
+# kernel-hardening-checker version
+__version__ = '0.6.6'
- return open_method(file, *args, **kwargs)
+def _open(file: str) -> TextIO:
+ if file.endswith('.gz'):
+ return gzip.open(file, 'rt', encoding='utf-8')
+ return open(file, 'rt', encoding='utf-8')
-def detect_arch(fname, archs):
- with _open(fname, 'rt', encoding='utf-8') as f:
- arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]+=y$")
+
+def detect_arch(fname: str, archs: List[str]) -> Tuple[StrOrNone, str]:
+ with _open(fname) as f:
+ arch_pattern = re.compile(r"CONFIG_[a-zA-Z0-9_]+=y$")
arch = None
for line in f.readlines():
if arch_pattern.match(line):
return arch, 'OK'
-def detect_kernel_version(fname):
- with _open(fname, 'rt', encoding='utf-8') as f:
- ver_pattern = re.compile("# Linux/.+ Kernel Configuration$")
+def detect_kernel_version(fname: str) -> Tuple[TupleOrNone, str]:
+ with _open(fname) as f:
+ ver_pattern = re.compile(r"^# Linux/.+ Kernel Configuration$|^Linux version .+")
for line in f.readlines():
if ver_pattern.match(line):
line = line.strip()
parts = line.split()
- ver_str = parts[2]
+ ver_str = parts[2].split('-', 1)[0]
ver_numbers = ver_str.split('.')
- if len(ver_numbers) < 3 or not ver_numbers[0].isdigit() or not ver_numbers[1].isdigit():
- msg = f'failed to parse the version "{ver_str}"'
- return None, msg
- return (int(ver_numbers[0]), int(ver_numbers[1])), None
+ if len(ver_numbers) >= 3:
+ if all(map(lambda x: x.isdecimal(), ver_numbers)):
+ return tuple(map(int, ver_numbers)), 'OK'
+ msg = f'failed to parse the version "{parts[2]}"'
+ return None, msg
return None, 'no kernel version detected'
-def detect_compiler(fname):
+def detect_compiler(fname: str) -> Tuple[StrOrNone, str]:
gcc_version = None
clang_version = None
- with _open(fname, 'rt', encoding='utf-8') as f:
+ with _open(fname) as f:
for line in f.readlines():
if line.startswith('CONFIG_GCC_VERSION='):
gcc_version = line[19:-1]
if gcc_version is None or clang_version is None:
return None, 'no CONFIG_GCC_VERSION or CONFIG_CLANG_VERSION'
if gcc_version == '0' and clang_version != '0':
- return 'CLANG ' + clang_version, 'OK'
+ return f'CLANG {clang_version}', 'OK'
if gcc_version != '0' and clang_version == '0':
- return 'GCC ' + gcc_version, 'OK'
+ return f'GCC {gcc_version}', 'OK'
sys.exit(f'[!] ERROR: invalid GCC_VERSION and CLANG_VERSION: {gcc_version} {clang_version}')
-def print_unknown_options(checklist, parsed_options):
- known_options = []
-
- for o1 in checklist:
- if o1.type != 'complex':
- known_options.append(o1.name)
- continue
- for o2 in o1.opts:
- if o2.type != 'complex':
- if hasattr(o2, 'name'):
- known_options.append(o2.name)
- continue
- for o3 in o2.opts:
- assert(o3.type != 'complex'), \
- f'unexpected ComplexOptCheck inside {o2.name}'
- if hasattr(o3, 'name'):
- known_options.append(o3.name)
-
- for option, value in parsed_options.items():
- if option not in known_options:
- print(f'[?] No check for option {option} ({value})')
-
-
-def print_checklist(mode, checklist, with_results):
+def print_checklist(mode: StrOrNone, checklist: List[ChecklistObjType], with_results: bool) -> None:
if mode == 'json':
output = []
for opt in checklist:
if with_results:
sep_line_len += 30
print('=' * sep_line_len)
- print(f'{"option name":^40}|{"type":^7}|{"desired val":^12}|{"decision":^10}|{"reason":^18}', end='')
+ print(f'{"option_name":^40}|{"type":^7}|{"desired_val":^12}|{"decision":^10}|{"reason":^18}', end='')
if with_results:
- print('| check result', end='')
+ print('| check_result', end='')
print()
print('=' * sep_line_len)
# table contents
+ ok_count = 0
+ fail_count = 0
for opt in checklist:
if with_results:
- if mode == 'show_ok':
- if not opt.result.startswith('OK'):
+ assert(opt.result), f'unexpected empty result of {opt.name} check'
+ if opt.result.startswith('OK'):
+ ok_count += 1
+ if mode == 'show_fail':
continue
- if mode == 'show_fail':
- if not opt.result.startswith('FAIL'):
+ elif opt.result.startswith('FAIL'):
+ fail_count += 1
+ if mode == 'show_ok':
continue
+ else:
+ assert(False), f'unexpected result "{opt.result}" of {opt.name} check'
opt.table_print(mode, with_results)
print()
if mode == 'verbose':
# final score
if with_results:
- fail_count = len(list(filter(lambda opt: opt.result.startswith('FAIL'), checklist)))
fail_suppressed = ''
- ok_count = len(list(filter(lambda opt: opt.result.startswith('OK'), checklist)))
ok_suppressed = ''
if mode == 'show_ok':
fail_suppressed = ' (suppressed in output)'
print(f'[+] Config check is finished: \'OK\' - {ok_count}{ok_suppressed} / \'FAIL\' - {fail_count}{fail_suppressed}')
-def parse_kconfig_file(mode, parsed_options, fname):
- with _open(fname, 'rt', encoding='utf-8') as f:
- opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]+=.+$")
- opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]+ is not set$")
+def parse_kconfig_file(_mode: StrOrNone, parsed_options: Dict[str, str], fname: str) -> None:
+ with _open(fname) as f:
+ opt_is_on = re.compile(r"CONFIG_[a-zA-Z0-9_]+=.+$")
+ opt_is_off = re.compile(r"# CONFIG_[a-zA-Z0-9_]+ is not set$")
for line in f.readlines():
line = line.strip()
sys.exit(f'[!] ERROR: Kconfig option "{line}" is found multiple times')
if option:
+ assert(value), f'unexpected empty value for {option}'
parsed_options[option] = value
-def parse_cmdline_file(mode, parsed_options, fname):
+def parse_cmdline_file(mode: StrOrNone, parsed_options: Dict[str, str], fname: str) -> None:
with open(fname, 'r', encoding='utf-8') as f:
line = f.readline()
opts = line.split()
if name in parsed_options and mode != 'json':
print(f'[!] WARNING: cmdline option "{name}" is found multiple times')
value = normalize_cmdline_options(name, value)
+ assert(value is not None), f'unexpected None value for {name}'
parsed_options[name] = value
-def parse_sysctl_file(mode, parsed_options, fname):
+def parse_sysctl_file(mode: StrOrNone, parsed_options: Dict[str, str], fname: str) -> None:
with open(fname, 'r', encoding='utf-8') as f:
- sysctl_pattern = re.compile("[a-zA-Z0-9/\._-]+ =.*$")
+ sysctl_pattern = re.compile(r"[a-zA-Z0-9/\._-]+ =.*$")
for line in f.readlines():
line = line.strip()
if not sysctl_pattern.match(line):
sys.exit(f'[!] ERROR: {fname} doesn\'t look like a sysctl output file, please try `sudo sysctl -a > {fname}`')
# let's check the presence of a sysctl option available for root
- if 'net.core.bpf_jit_harden' not in parsed_options and mode != 'json':
- print(f'[!] WARNING: sysctl option "net.core.bpf_jit_harden" available for root is not found in {fname}, please try `sudo sysctl -a > {fname}`')
+ if 'kernel.cad_pid' not in parsed_options and mode != 'json':
+ print(f'[!] WARNING: sysctl option "kernel.cad_pid" available for root is not found in {fname}, please try `sudo sysctl -a > {fname}`')
-def main():
+def main() -> None:
# Report modes:
# * verbose mode for
# - reporting about unknown kernel options in the Kconfig
supported_archs = ['X86_64', 'X86_32', 'ARM64', 'ARM']
parser = ArgumentParser(prog='kernel-hardening-checker',
description='A tool for checking the security hardening options of the Linux kernel')
- parser.add_argument('--version', action='version', version='%(prog)s ' + __version__)
+ parser.add_argument('--version', action='version', version=f'%(prog)s {__version__}')
parser.add_argument('-m', '--mode', choices=report_modes,
help='choose the report mode')
parser.add_argument('-c', '--config',
help='check the security hardening options in the kernel cmdline file (contents of /proc/cmdline)')
parser.add_argument('-s', '--sysctl',
help='check the security hardening options in the sysctl output file (`sudo sysctl -a > file`)')
+ parser.add_argument('-v', '--kernel-version',
+ help='extract the version from the kernel version file (contents of /proc/version)')
parser.add_argument('-p', '--print', choices=supported_archs,
help='print the security hardening recommendations for the selected microarchitecture')
parser.add_argument('-g', '--generate', choices=supported_archs,
if mode != 'json':
print(f'[+] Special report mode: {mode}')
- config_checklist = []
+ config_checklist = [] # type: List[ChecklistObjType]
if args.config:
if args.print:
if mode != 'json':
print(f'[+] Detected microarchitecture: {arch}')
- kernel_version, msg = detect_kernel_version(args.config)
+ if args.kernel_version:
+ kernel_version, msg = detect_kernel_version(args.kernel_version)
+ else:
+ kernel_version, msg = detect_kernel_version(args.config)
if kernel_version is None:
+ if args.kernel_version is None:
+ print('[!] Hint: provide the kernel version file through --kernel-version option')
sys.exit(f'[!] ERROR: {msg}')
if mode != 'json':
- print(f'[+] Detected kernel version: {kernel_version[0]}.{kernel_version[1]}')
+ print(f'[+] Detected kernel version: {kernel_version}')
compiler, msg = detect_compiler(args.config)
if mode != 'json':
add_sysctl_checks(config_checklist, arch)
# populate the checklist with the parsed Kconfig data
- parsed_kconfig_options = OrderedDict()
+ parsed_kconfig_options = {} # type: Dict[str, str]
parse_kconfig_file(mode, parsed_kconfig_options, args.config)
populate_with_data(config_checklist, parsed_kconfig_options, 'kconfig')
if args.cmdline:
# populate the checklist with the parsed cmdline data
- parsed_cmdline_options = OrderedDict()
+ parsed_cmdline_options = {} # type: Dict[str, str]
parse_cmdline_file(mode, parsed_cmdline_options, args.cmdline)
populate_with_data(config_checklist, parsed_cmdline_options, 'cmdline')
if args.sysctl:
# populate the checklist with the parsed sysctl data
- parsed_sysctl_options = OrderedDict()
+ parsed_sysctl_options = {} # type: Dict[str, str]
parse_sysctl_file(mode, parsed_sysctl_options, args.sysctl)
populate_with_data(config_checklist, parsed_sysctl_options, 'sysctl')
mmap_rnd_bits_max = parsed_kconfig_options.get('CONFIG_ARCH_MMAP_RND_BITS_MAX', None)
if mmap_rnd_bits_max:
override_expected_value(config_checklist, 'CONFIG_ARCH_MMAP_RND_BITS', mmap_rnd_bits_max)
+ else:
+ # remove the CONFIG_ARCH_MMAP_RND_BITS check to avoid false results
+ if mode != 'json':
+ print('[-] Can\'t check CONFIG_ARCH_MMAP_RND_BITS without CONFIG_ARCH_MMAP_RND_BITS_MAX')
+ config_checklist[:] = [o for o in config_checklist if o.name != 'CONFIG_ARCH_MMAP_RND_BITS']
# now everything is ready, perform the checks
perform_checks(config_checklist)
if mode == 'verbose':
# print the parsed options without the checks (for debugging)
- all_parsed_options = parsed_kconfig_options # assignment does not copy
+ print_unknown_options(config_checklist, parsed_kconfig_options, 'kconfig')
if args.cmdline:
- all_parsed_options.update(parsed_cmdline_options)
+ print_unknown_options(config_checklist, parsed_cmdline_options, 'cmdline')
if args.sysctl:
- all_parsed_options.update(parsed_sysctl_options)
- print_unknown_options(config_checklist, all_parsed_options)
+ print_unknown_options(config_checklist, parsed_sysctl_options, 'sysctl')
# finally print the results
print_checklist(mode, config_checklist, True)
add_sysctl_checks(config_checklist, None)
# populate the checklist with the parsed sysctl data
- parsed_sysctl_options = OrderedDict()
+ parsed_sysctl_options = {}
parse_sysctl_file(mode, parsed_sysctl_options, args.sysctl)
populate_with_data(config_checklist, parsed_sysctl_options, 'sysctl')
if mode == 'verbose':
# print the parsed options without the checks (for debugging)
- print_unknown_options(config_checklist, parsed_sysctl_options)
+ print_unknown_options(config_checklist, parsed_sysctl_options, 'sysctl')
# finally print the results
print_checklist(mode, config_checklist, True)
if mode and mode not in ('verbose', 'json'):
sys.exit(f'[!] ERROR: wrong mode "{mode}" for --print')
arch = args.print
+ assert(arch), 'unexpected empty arch from ArgumentParser'
add_kconfig_checks(config_checklist, arch)
add_cmdline_checks(config_checklist, arch)
add_sysctl_checks(config_checklist, arch)
sys.exit(0)
if args.generate:
- assert(args.config is None and args.cmdline is None and args.sysctl is None and args.print is None), 'unexpected args'
+ assert(args.config is None and
+ args.cmdline is None and
+ args.sysctl is None and
+ args.print is None), \
+ 'unexpected args'
if mode:
sys.exit(f'[!] ERROR: wrong mode "{mode}" for --generate')
arch = args.generate
+ assert(arch), 'unexpected empty arch from ArgumentParser'
add_kconfig_checks(config_checklist, arch)
print(f'CONFIG_{arch}=y') # the Kconfig fragment should describe the microarchitecture
for opt in config_checklist:
if opt.name == 'CONFIG_ARCH_MMAP_RND_BITS':
continue # don't add CONFIG_ARCH_MMAP_RND_BITS because its value needs refinement
+ if opt.expected == 'is not off':
+ continue # don't add Kconfig options without explicitly recommended values
if opt.expected == 'is not set':
print(f'# {opt.name} is not set')
else: