#!/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!
+This tool is for checking the security hardening options of the Linux kernel.
Author: Alexander Popov <alex.popov@linux.com>
# 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
+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
+
+
+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, 'r', encoding='utf-8') as f:
- arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]*=y")
+ with _open(fname, 'rt', encoding='utf-8') as f:
+ arch_pattern = re.compile("CONFIG_[a-zA-Z0-9_]+=y$")
arch = None
for line in f.readlines():
if arch_pattern.match(line):
if arch is None:
arch = option
else:
- return None, 'more than one supported architecture is detected'
+ return None, 'detected more than one microarchitecture'
if arch is None:
- return None, 'failed to detect architecture'
+ return None, 'failed to detect microarchitecture'
return arch, 'OK'
def detect_kernel_version(fname):
- with open(fname, 'r', encoding='utf-8') as f:
- ver_pattern = re.compile("# Linux/.* Kernel Configuration")
+ with _open(fname, 'rt', encoding='utf-8') as f:
+ ver_pattern = re.compile("# Linux/.+ Kernel Configuration$")
for line in f.readlines():
if ver_pattern.match(line):
line = line.strip()
def detect_compiler(fname):
gcc_version = None
clang_version = None
- with open(fname, 'r', 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]*")
+ with _open(fname, 'rt', encoding='utf-8') as f:
for line in f.readlines():
- if gcc_version_pattern.match(line):
+ if line.startswith('CONFIG_GCC_VERSION='):
gcc_version = line[19:-1]
- if clang_version_pattern.match(line):
+ if line.startswith('CONFIG_CLANG_VERSION='):
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'
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, 'r', 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")
+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_]+=.+$")
+ opt_is_off = re.compile("# CONFIG_[a-zA-Z0-9_]+ is not set$")
for line in f.readlines():
line = line.strip()
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}"')
+ 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}"')
+ assert(value == 'is not set'), \
+ f'unexpected value of disabled Kconfig option "{line}"'
+ elif line != '' and not line.startswith('#') and mode != 'json':
+ print(f'[!] WARNING: strange line in Kconfig file: "{line}"')
if option in parsed_options:
- sys.exit(f'[!] ERROR: kconfig option "{line}" exists multiple times')
+ sys.exit(f'[!] ERROR: Kconfig option "{line}" is found multiple times')
if option:
parsed_options[option] = value
-def parse_cmdline_file(parsed_options, fname):
+def parse_cmdline_file(mode, parsed_options, fname):
with open(fname, 'r', encoding='utf-8') as f:
line = f.readline()
opts = line.split()
else:
name = opt
value = '' # '' is not None
+ if name in parsed_options and mode != 'json':
+ print(f'[!] WARNING: cmdline option "{name}" is found multiple times')
value = normalize_cmdline_options(name, value)
parsed_options[name] = value
+def parse_sysctl_file(mode, parsed_options, fname):
+ with open(fname, 'r', encoding='utf-8') as f:
+ sysctl_pattern = re.compile("[a-zA-Z0-9\._-]+ =.*$")
+ for line in f.readlines():
+ line = line.strip()
+ if not sysctl_pattern.match(line):
+ sys.exit(f'[!] ERROR: unexpected line in sysctl file: {line}')
+ option, value = line.split('=', 1)
+ option = option.strip()
+ value = value.strip()
+ # sysctl options may be found multiple times, let's save the last value:
+ parsed_options[option] = value
+
+ # let's check the presence of some ancient sysctl option
+ # to ensure that we are parsing the output of `sudo sysctl -a > file`
+ if 'kernel.printk' not in parsed_options:
+ 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}`')
+
+
def main():
# Report modes:
# * verbose mode for
- # - reporting about unknown kernel options in the kconfig
+ # - 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']
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')
+ parser.add_argument('-c', '--config',
+ help='check the security hardening options in the kernel Kconfig file (also supports *.gz files)')
+ parser.add_argument('-l', '--cmdline',
+ 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('-p', '--print', choices=supported_archs,
+ help='print the security hardening recommendations for the selected microarchitecture')
+ parser.add_argument('-g', '--generate', choices=supported_archs,
+ help='generate a Kconfig fragment with the security hardening options for the selected microarchitecture')
args = parser.parse_args()
mode = None
if args.print:
sys.exit('[!] ERROR: --config and --print can\'t be used together')
+ if args.generate:
+ sys.exit('[!] ERROR: --config and --generate 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}')
+ if args.sysctl:
+ print(f'[+] Sysctl output file to check: {args.sysctl}')
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}')
+ print(f'[+] Detected microarchitecture: {arch}')
kernel_version, msg = detect_kernel_version(args.config)
if kernel_version is None:
else:
print(f'[-] Can\'t detect the compiler: {msg}')
- # add relevant kconfig checks to the checklist
+ # 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
+ if args.sysctl:
+ # add relevant sysctl checks to the checklist
+ add_sysctl_checks(config_checklist, arch)
+
+ # populate the checklist with the parsed Kconfig data
parsed_kconfig_options = OrderedDict()
- parse_kconfig_file(parsed_kconfig_options, args.config)
+ parse_kconfig_file(mode, parsed_kconfig_options, args.config)
populate_with_data(config_checklist, parsed_kconfig_options, 'kconfig')
# populate the checklist with the kernel version data
if args.cmdline:
# populate the checklist with the parsed cmdline data
parsed_cmdline_options = OrderedDict()
- parse_cmdline_file(parsed_cmdline_options, args.cmdline)
+ 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()
+ parse_sysctl_file(mode, parsed_sysctl_options, args.sysctl)
+ populate_with_data(config_checklist, parsed_sysctl_options, 'sysctl')
+
+ # hackish refinement of the CONFIG_ARCH_MMAP_RND_BITS check
+ 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)
+
# now everything is ready, perform the checks
perform_checks(config_checklist)
all_parsed_options = parsed_kconfig_options # assignment does not copy
if args.cmdline:
all_parsed_options.update(parsed_cmdline_options)
+ if args.sysctl:
+ all_parsed_options.update(parsed_sysctl_options)
print_unknown_options(config_checklist, all_parsed_options)
# finally print the results
sys.exit(0)
elif args.cmdline:
- sys.exit('[!] ERROR: checking cmdline doesn\'t work without checking kconfig')
+ sys.exit('[!] ERROR: checking cmdline depends on checking Kconfig')
+ elif args.sysctl:
+ # TODO: sysctl check should also work separately
+ sys.exit('[!] ERROR: checking sysctl depends on checking Kconfig')
if args.print:
- if mode in ('show_ok', 'show_fail'):
+ assert(args.config is None and args.cmdline is None and args.sysctl is None), 'unexpected args'
+ if args.generate:
+ sys.exit('[!] ERROR: --print and --generate can\'t be used together')
+ if mode and mode not in ('verbose', 'json'):
sys.exit(f'[!] ERROR: wrong mode "{mode}" for --print')
arch = args.print
add_kconfig_checks(config_checklist, arch)
add_cmdline_checks(config_checklist, arch)
+ add_sysctl_checks(config_checklist, arch)
if mode != 'json':
- print(f'[+] Printing kernel security hardening preferences for {arch}...')
+ print(f'[+] Printing kernel security hardening options for {arch}...')
print_checklist(mode, config_checklist, False)
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'
+ if mode:
+ sys.exit(f'[!] ERROR: wrong mode "{mode}" for --generate')
+ arch = args.generate
+ 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 set':
+ print(f'# {opt.name} is not set')
+ else:
+ print(f'{opt.name}={opt.expected}')
+ sys.exit(0)
+
parser.print_help()
sys.exit(0)
projects / kconfig-hardened-check.git / blobdiff