#!/usr/bin/python3
"""
This tool helps me to check Linux kernel options against
my security hardening preferences for X86_64, ARM64, X86_32, and ARM.
Let the computers do their job!
Author: Alexander Popov <alex.popov@linux.com>
This module performs input/output.
"""
# pylint: disable=missing-function-docstring,line-too-long,invalid-name,too-many-branches,too-many-statements
import gzip
import sys
from argparse import ArgumentParser
from collections import OrderedDict
import re
import json
from .__about__ import __version__
from .checks import add_kconfig_checks, add_cmdline_checks, normalize_cmdline_options
from .engine import populate_with_data, perform_checks
def _open(file: str, *args, **kwargs):
open_method = open
if file.endswith(".gz"):
open_method = gzip.open
return open_method(file, *args, **kwargs)
def detect_arch(fname, archs):
with _open(fname, 'rt', encoding='utf-8') as f:
arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
arch = None
for line in f.readlines():
if arch_pattern.match(line):
option, _ = line[7:].split('=', 1)
if option in archs:
if arch is None:
arch = option
else:
return None, 'more than one supported architecture is detected'
if arch is None:
return None, 'failed to detect architecture'
return arch, 'OK'
def detect_kernel_version(fname):
with _open(fname, 'rt', encoding='utf-8') as f:
ver_pattern = re.compile("# Linux/.* Kernel Configuration")
for line in f.readlines():
if ver_pattern.match(line):
line = line.strip()
parts = line.split()
ver_str = parts[2]
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
return None, 'no kernel version detected'
def detect_compiler(fname):
gcc_version = None
clang_version = None
with _open(fname, 'rt', encoding='utf-8') as f:
gcc_version_pattern = re.compile("CONFIG_GCC_VERSION=[0-9]*")
clang_version_pattern = re.compile("CONFIG_CLANG_VERSION=[0-9]*")
for line in f.readlines():
if gcc_version_pattern.match(line):
gcc_version = line[19:-1]
if clang_version_pattern.match(line):
clang_version = line[21:-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'
if gcc_version != '0' and clang_version == '0':
return '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):
if mode == 'json':
output = []
for opt in checklist:
output.append(opt.json_dump(with_results))
print(json.dumps(output))
return
# table header
sep_line_len = 91
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='')
if with_results:
print('| check result', end='')
print()
print('=' * sep_line_len)
# table contents
for opt in checklist:
if with_results:
if mode == 'show_ok':
if not opt.result.startswith('OK'):
continue
if mode == 'show_fail':
if not opt.result.startswith('FAIL'):
continue
opt.table_print(mode, with_results)
print()
if mode == 'verbose':
print('-' * sep_line_len)
print()
# 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)'
if mode == 'show_fail':
ok_suppressed = ' (suppressed in output)'
print(f'[+] Config check is finished: \'OK\' - {ok_count}{ok_suppressed} / \'FAIL\' - {fail_count}{fail_suppressed}')
def parse_kconfig_file(parsed_options, fname):
with _open(fname, 'rt', encoding='utf-8') as f:
opt_is_on = re.compile("CONFIG_[a-zA-Z0-9_]*=[a-zA-Z0-9_\"]*")
opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]* is not set")
for line in f.readlines():
line = line.strip()
option = None
value = None
if opt_is_on.match(line):
option, value = line.split('=', 1)
if value == 'is not set':
sys.exit(f'[!] ERROR: bad enabled kconfig option "{line}"')
elif opt_is_off.match(line):
option, value = line[2:].split(' ', 1)
if value != 'is not set':
sys.exit(f'[!] ERROR: bad disabled kconfig option "{line}"')
if option in parsed_options:
sys.exit(f'[!] ERROR: kconfig option "{line}" exists multiple times')
if option:
parsed_options[option] = value
def parse_cmdline_file(parsed_options, fname):
with open(fname, 'r', encoding='utf-8') as f:
line = f.readline()
opts = line.split()
line = f.readline()
if line:
sys.exit(f'[!] ERROR: more than one line in "{fname}"')
for opt in opts:
if '=' in opt:
name, value = opt.split('=', 1)
else:
name = opt
value = '' # '' is not None
value = normalize_cmdline_options(name, value)
parsed_options[name] = value
def main():
# Report modes:
# * verbose mode for
# - reporting about unknown kernel options in the kconfig
# - verbose printing of ComplexOptCheck items
# * json mode for printing the results in JSON format
report_modes = ['verbose', 'json', 'show_ok', 'show_fail']
supported_archs = ['X86_64', 'X86_32', 'ARM64', 'ARM']
parser = ArgumentParser(prog='kconfig-hardened-check',
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('-p', '--print', choices=supported_archs,
help='print security hardening preferences for the selected architecture')
parser.add_argument('-c', '--config',
help='check the kernel kconfig file against these preferences')
parser.add_argument('-l', '--cmdline',
help='check the kernel cmdline file against these preferences')
parser.add_argument('-m', '--mode', choices=report_modes,
help='choose the report mode')
args = parser.parse_args()
mode = None
if args.mode:
mode = args.mode
if mode != 'json':
print(f'[+] Special report mode: {mode}')
config_checklist = []
if args.config:
if args.print:
sys.exit('[!] ERROR: --config and --print can\'t be used together')
if mode != 'json':
print(f'[+] Kconfig file to check: {args.config}')
if args.cmdline:
print(f'[+] Kernel cmdline file to check: {args.cmdline}')
arch, msg = detect_arch(args.config, supported_archs)
if arch is None:
sys.exit(f'[!] ERROR: {msg}')
if mode != 'json':
print(f'[+] Detected architecture: {arch}')
kernel_version, msg = detect_kernel_version(args.config)
if kernel_version is None:
sys.exit(f'[!] ERROR: {msg}')
if mode != 'json':
print(f'[+] Detected kernel version: {kernel_version[0]}.{kernel_version[1]}')
compiler, msg = detect_compiler(args.config)
if mode != 'json':
if compiler:
print(f'[+] Detected compiler: {compiler}')
else:
print(f'[-] Can\'t detect the compiler: {msg}')
# add relevant kconfig checks to the checklist
add_kconfig_checks(config_checklist, arch)
if args.cmdline:
# add relevant cmdline checks to the checklist
add_cmdline_checks(config_checklist, arch)
# populate the checklist with the parsed kconfig data
parsed_kconfig_options = OrderedDict()
parse_kconfig_file(parsed_kconfig_options, args.config)
populate_with_data(config_checklist, parsed_kconfig_options, 'kconfig')
# populate the checklist with the kernel version data
populate_with_data(config_checklist, kernel_version, 'version')
if args.cmdline:
# populate the checklist with the parsed cmdline data
parsed_cmdline_options = OrderedDict()
parse_cmdline_file(parsed_cmdline_options, args.cmdline)
populate_with_data(config_checklist, parsed_cmdline_options, 'cmdline')
# 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
if args.cmdline:
all_parsed_options.update(parsed_cmdline_options)
print_unknown_options(config_checklist, all_parsed_options)
# finally print the results
print_checklist(mode, config_checklist, True)
sys.exit(0)
elif args.cmdline:
sys.exit('[!] ERROR: checking cmdline doesn\'t work without checking kconfig')
if args.print:
if mode in ('show_ok', 'show_fail'):
sys.exit(f'[!] ERROR: wrong mode "{mode}" for --print')
arch = args.print
add_kconfig_checks(config_checklist, arch)
add_cmdline_checks(config_checklist, arch)
if mode != 'json':
print(f'[+] Printing kernel security hardening preferences for {arch}...')
print_checklist(mode, config_checklist, False)
sys.exit(0)
parser.print_help()
sys.exit(0)