-# Kconfig hardened check
+# kconfig-hardened-check
+
+
+[](https://codecov.io/gh/a13xp0p0v/kconfig-hardened-check)
## Motivation
- [KSPP recommended settings][1],
- [CLIP OS kernel configuration][2],
- - last public [grsecurity][3] patch (options which they disable).
+ - last public [grsecurity][3] patch (options which they disable),
+ - [SECURITY_LOCKDOWN_LSM][5] patchset,
+ - direct feedback from Linux kernel maintainers (Daniel Vetter in [issue #38][6]).
I also created [__Linux Kernel Defence Map__][4] that is a graphical representation of the
relationships between these hardening features and the corresponding vulnerability classes
- ARM64
- ARM
-## Script output examples
+## Installation
+
+You can install the package:
-### Usage
```
-usage: kconfig-hardened-check.py [-h] [-p {X86_64,X86_32,ARM64,ARM}]
- [-c CONFIG] [--debug] [--json]
+pip install git+https://github.com/a13xp0p0v/kconfig-hardened-check
+```
+
+or simply run `./bin/kconfig-hardened-check` from the cloned repository.
+
+## Usage
+```
+usage: kconfig-hardened-check [-h] [-p {X86_64,X86_32,ARM64,ARM}] [-c CONFIG]
+ [--debug] [--json] [--version]
Checks the hardening options in the Linux kernel config
print hardening preferences for selected architecture
-c CONFIG, --config CONFIG
check the config_file against these preferences
- --debug enable internal debug mode (not for production use)
+ --debug enable verbose debug mode
--json print results in JSON format
+ --version show program's version number and exit
```
-### Script output for `Ubuntu 18.04 (Bionic Beaver with HWE)` kernel config
+## Output for `Ubuntu 20.04 LTS (Focal Fossa)` kernel config
```
-$ ./kconfig-hardened-check.py -c config_files/distros/ubuntu-bionic-generic.config
-[+] Trying to detect architecture in "config_files/distros/ubuntu-bionic-generic.config"...
+$ ./bin/kconfig-hardened-check -c kconfig_hardened_check/config_files/distros/ubuntu-focal.config
+[+] Trying to detect architecture in "kconfig_hardened_check/config_files/distros/ubuntu-focal.config"...
[+] Detected architecture: X86_64
-[+] Trying to detect kernel version in "config_files/distros/ubuntu-bionic-generic.config"...
-[+] Found version line: "# Linux/x86 5.3.0-28-generic Kernel Configuration"
-[+] Detected kernel version: 5.3
-[+] Checking "config_files/distros/ubuntu-bionic-generic.config" against X86_64 hardening preferences...
+[+] Trying to detect kernel version in "kconfig_hardened_check/config_files/distros/ubuntu-focal.config"...
+[+] Found version line: "# Linux/x86 5.4.0-29-generic Kernel Configuration"
+[+] Detected kernel version: 5.4
+[+] Checking "kconfig_hardened_check/config_files/distros/ubuntu-focal.config" against X86_64 hardening preferences...
=========================================================================================================================
option name | desired val | decision | reason | check result
=========================================================================================================================
CONFIG_STRICT_MODULE_RWX | y |defconfig | self_protection | OK
CONFIG_GCC_PLUGINS | y |defconfig | self_protection | FAIL: not found
CONFIG_REFCOUNT_FULL | y |defconfig | self_protection | FAIL: "is not set"
+CONFIG_IOMMU_SUPPORT | y |defconfig | self_protection | OK
CONFIG_MICROCODE | y |defconfig | self_protection | OK
CONFIG_RETPOLINE | y |defconfig | self_protection | OK
CONFIG_X86_SMAP | y |defconfig | self_protection | OK
CONFIG_X86_UMIP | y |defconfig | self_protection | OK: CONFIG_X86_INTEL_UMIP "y"
-CONFIG_IOMMU_SUPPORT | y |defconfig | self_protection | OK
CONFIG_SYN_COOKIES | y |defconfig | self_protection | OK
CONFIG_PAGE_TABLE_ISOLATION | y |defconfig | self_protection | OK
CONFIG_RANDOMIZE_MEMORY | y |defconfig | self_protection | OK
CONFIG_STATIC_USERMODEHELPER | y | clipos | self_protection | FAIL: "is not set"
CONFIG_SLAB_MERGE_DEFAULT | is not set | clipos | self_protection | FAIL: "y"
CONFIG_GCC_PLUGIN_RANDSTRUCT_PERFORMANCE | is not set | clipos | self_protection | FAIL: CONFIG_GCC_PLUGIN_RANDSTRUCT is needed
+CONFIG_RANDOM_TRUST_BOOTLOADER | is not set | clipos | self_protection | FAIL: "y"
CONFIG_RANDOM_TRUST_CPU | is not set | clipos | self_protection | FAIL: "y"
CONFIG_INTEL_IOMMU_SVM | y | clipos | self_protection | OK
CONFIG_INTEL_IOMMU_DEFAULT_ON | y | clipos | self_protection | FAIL: "is not set"
CONFIG_AMD_IOMMU_V2 | y | my | self_protection | FAIL: "m"
CONFIG_SECURITY | y |defconfig | security_policy | OK
CONFIG_SECURITY_YAMA | y | kspp | security_policy | OK
+CONFIG_SECURITY_WRITABLE_HOOKS | is not set | my | security_policy | OK: not found
+CONFIG_SECURITY_LOCKDOWN_LSM | y | clipos | security_policy | OK
+CONFIG_SECURITY_LOCKDOWN_LSM_EARLY | y | clipos | security_policy | OK
+CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY| y | clipos | security_policy | FAIL: "is not set"
CONFIG_SECURITY_LOADPIN | y | my | security_policy | FAIL: "is not set"
-CONFIG_SECURITY_LOCKDOWN_LSM | y | my | security_policy | FAIL: not found
-CONFIG_SECURITY_LOCKDOWN_LSM_EARLY | y | my | security_policy | FAIL: not found
-CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY| y | my | security_policy | FAIL: not found
+CONFIG_SECURITY_LOADPIN_ENFORCE | y | my | security_policy | FAIL: CONFIG_SECURITY_LOADPIN is needed
CONFIG_SECURITY_SAFESETID | y | my | security_policy | OK
-CONFIG_SECURITY_WRITABLE_HOOKS | is not set | my | security_policy | OK: not found
CONFIG_SECCOMP | y |defconfig | cut_attack_surface | OK
CONFIG_SECCOMP_FILTER | y |defconfig | cut_attack_surface | OK
CONFIG_STRICT_DEVMEM | y |defconfig | cut_attack_surface | OK
CONFIG_MODULES | is not set | kspp | cut_attack_surface | FAIL: "y"
CONFIG_DEVMEM | is not set | kspp | cut_attack_surface | FAIL: "y"
CONFIG_IO_STRICT_DEVMEM | y | kspp | cut_attack_surface | FAIL: "is not set"
+CONFIG_LEGACY_VSYSCALL_NONE | y | kspp | cut_attack_surface | FAIL: "is not set"
CONFIG_ACPI_CUSTOM_METHOD | is not set | kspp | cut_attack_surface | OK
CONFIG_COMPAT_BRK | is not set | kspp | cut_attack_surface | OK
CONFIG_DEVKMEM | is not set | kspp | cut_attack_surface | OK
CONFIG_PROC_KCORE | is not set | kspp | cut_attack_surface | FAIL: "y"
CONFIG_LEGACY_PTYS | is not set | kspp | cut_attack_surface | FAIL: "y"
CONFIG_HIBERNATION | is not set | kspp | cut_attack_surface | FAIL: "y"
-CONFIG_LEGACY_VSYSCALL_NONE | y | kspp | cut_attack_surface | FAIL: "is not set"
CONFIG_IA32_EMULATION | is not set | kspp | cut_attack_surface | FAIL: "y"
CONFIG_X86_X32 | is not set | kspp | cut_attack_surface | FAIL: "y"
CONFIG_MODIFY_LDT_SYSCALL | is not set | kspp | cut_attack_surface | FAIL: "y"
+CONFIG_OABI_COMPAT | is not set | kspp | cut_attack_surface | OK: not found
CONFIG_X86_PTDUMP | is not set |grsecurity| cut_attack_surface | OK
CONFIG_ZSMALLOC_STAT | is not set |grsecurity| cut_attack_surface | OK
CONFIG_PAGE_OWNER | is not set |grsecurity| cut_attack_surface | OK
CONFIG_DEVPORT | is not set |grsecurity| cut_attack_surface | FAIL: "y"
CONFIG_DEBUG_FS | is not set |grsecurity| cut_attack_surface | FAIL: "y"
CONFIG_NOTIFIER_ERROR_INJECTION | is not set |grsecurity| cut_attack_surface | FAIL: "m"
+CONFIG_DRM_LEGACY | is not set |maintainer| cut_attack_surface | OK
+CONFIG_FB | is not set |maintainer| cut_attack_surface | FAIL: "y"
+CONFIG_VT | is not set |maintainer| cut_attack_surface | FAIL: "y"
CONFIG_ACPI_TABLE_UPGRADE | is not set | lockdown | cut_attack_surface | FAIL: "y"
-CONFIG_ACPI_APEI_EINJ | is not set | lockdown | cut_attack_surface | FAIL: "m"
-CONFIG_PROFILING | is not set | lockdown | cut_attack_surface | FAIL: "y"
+CONFIG_X86_IOPL_IOPERM | is not set | lockdown | cut_attack_surface | OK: not found
+CONFIG_EFI_TEST | is not set | lockdown | cut_attack_surface | FAIL: "m"
CONFIG_BPF_SYSCALL | is not set | lockdown | cut_attack_surface | FAIL: "y"
CONFIG_MMIOTRACE_TEST | is not set | lockdown | cut_attack_surface | OK
+CONFIG_X86_INTEL_TSX_MODE_OFF | y | clipos | cut_attack_surface | OK
+CONFIG_STAGING | is not set | clipos | cut_attack_surface | FAIL: "y"
CONFIG_KSM | is not set | clipos | cut_attack_surface | FAIL: "y"
CONFIG_KALLSYMS | is not set | clipos | cut_attack_surface | FAIL: "y"
CONFIG_X86_VSYSCALL_EMULATION | is not set | clipos | cut_attack_surface | FAIL: "y"
CONFIG_MAGIC_SYSRQ | is not set | clipos | cut_attack_surface | FAIL: "y"
CONFIG_KEXEC_FILE | is not set | clipos | cut_attack_surface | FAIL: "y"
CONFIG_USER_NS | is not set | clipos | cut_attack_surface | FAIL: "y"
+CONFIG_X86_MSR | is not set | clipos | cut_attack_surface | FAIL: "m"
+CONFIG_X86_CPUID | is not set | clipos | cut_attack_surface | FAIL: "m"
CONFIG_LDISC_AUTOLOAD | is not set | clipos | cut_attack_surface | FAIL: "y"
+CONFIG_AIO | is not set |grapheneos| cut_attack_surface | FAIL: "y"
CONFIG_MMIOTRACE | is not set | my | cut_attack_surface | FAIL: "y"
CONFIG_LIVEPATCH | is not set | my | cut_attack_surface | FAIL: "y"
CONFIG_IP_DCCP | is not set | my | cut_attack_surface | FAIL: "m"
CONFIG_FTRACE | is not set | my | cut_attack_surface | FAIL: "y"
CONFIG_BPF_JIT | is not set | my | cut_attack_surface | FAIL: "y"
CONFIG_VIDEO_VIVID | is not set | my | cut_attack_surface | FAIL: "m"
+CONFIG_INPUT_EVBUG | is not set | my | cut_attack_surface | FAIL: "m"
+CONFIG_INTEGRITY | y |defconfig |userspace_hardening | OK
CONFIG_ARCH_MMAP_RND_BITS | 32 | clipos |userspace_hardening | FAIL: "28"
-[+] config check is finished: 'OK' - 50 / 'FAIL' - 73
+[+] config check is finished: 'OK' - 57 / 'FAIL' - 79
```
## kconfig-hardened-check versioning
So the version of `kconfig-hardened-check` is associated with the corresponding version of the kernel.
-The version format is: __[major_number].[kernel_version]__
-
-The current version of `kconfig-hardened-check` is __0.5.3__, it's marked with the git tag.
+The version format is: __[major_number].[kernel_version].[kernel_patchlevel]__
## Questions and answers
__Q:__ How disabling `CONFIG_USER_NS` cuts the attack surface? It's needed for containers!
__A:__ Yes, the `CONFIG_USER_NS` option provides some isolation between the userspace programs,
-but the script recommends disabling it to cut the attack surface __of the kernel__.
+but the tool recommends disabling it to cut the attack surface __of the kernel__.
The rationale:
attacks for the whole system (kernel oops is not a rare situation). I think having `CONFIG_BUG` is enough here --
if we have a kernel oops in the process context, the offending/attacking process is killed.
+<br />
+
+__Q:__ What about performance impact of these kernel hardening options?
+
+__A:__ Ike Devolder [@BlackIkeEagle][7] made some performance tests and described the results in [this article][8].
+
[1]: http://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project/Recommended_Settings
[2]: https://docs.clip-os.org/clipos/kernel.html#configuration
[3]: https://grsecurity.net/
[4]: https://github.com/a13xp0p0v/linux-kernel-defence-map
+[5]: https://lwn.net/Articles/791863/
+[6]: https://github.com/a13xp0p0v/kconfig-hardened-check/issues/38
+[7]: https://github.com/BlackIkeEagle
+[8]: https://blog.herecura.eu/blog/2020-05-30-kconfig-hardening-tests/
projects / kconfig-hardened-check.git / blobdiff