Linux Kernel Runtime Guard (LKRG)
- 1 Introduction
- 2 Download
- 3 LKRG Overview
- 4 Installation
- 5 Configuration
- 6 Usage
- 7 Debugging
- 8 Additional Resources
- 9 References
LKRG is Freedom Software / Open Source. 
The focus of this wiki page is to provide simplified user documentation and easy installation of LKRG in Debian, Kicksecure, Qubes, Whonix, and perhaps Debian-based Linux distributions. This is a lightweight software fork [archive] and no changes will be made to the core of LKRG. Packaging is only provided for Debian. Links to the official LKRG homepage [archive] and other original resources can be found here.
This is only a very brief introduction, since LKRG technical details are not the focus of this page.
Linux Kernel Runtime Guard (LKRG) is a loadable kernel module that performs runtime integrity checking of the Linux kernel and detection of security vulnerability exploits against the kernel. As controversial as this concept is, LKRG attempts to post-detect and hopefully promptly respond to unauthorized modifications to the running Linux kernel (integrity checking) or to credentials (such as user IDs) of the running processes (exploit detection). For process credentials, LKRG attempts to detect the exploit and take action before the kernel would grant the process access (such as open a file) based on the unauthorized credentials. 
The Linux Kernel Runtime Guard protects system by comparing hashes which are calculated from the most important kernel region / sections / structures with the internal database hashes. Additionally, special efforts have been made to individually protect all extensions of the kernel (modules). To make the project fully functional, the module should be initially loaded on a clean system – e.g. directly after installation or after booting clean system. At this moment it is possible to create a trusted database of hashes. 
To learn more about LKRG, interested readers can:
- review the official LKRG homepage [archive]
- watch the LKRG Presentation Video [archive] or LKRG Presentation Slides [archive]
- read the LKRG Wiki [archive]
- consult other Upstream Resources
No benchmarks have yet been performed, but it appears the performance penalty is around
2.5% for fully enabled LKRG. 
LKRG Free vs LKRG Pro
Contacted upstream LKRG developers privately. To paraphrase: "We don’t oppose you packaging it. As long as LKRG exists, there will always be a free and libre version. There is no pro version yet. A hypothetical future pro version would not change that." In my words: "there won’t be a grsecurity alike situation where everything gets closed down".
We will likely use GPLv2 at least for LKRG free. We might or might not use a different license for LKRG Pro, if we ever make it.
Users who benefit from LKRG Free are encouraged to support its further development. However, at the time of writing they are not accepting donations: 
We used to accept donations for LKRG via Patreon, but we currently don't. Some of our former supporters are listed in the PATREON file in LKRG distribution tarballs.
Note: Users who require better security can Build the Linux Kernel Runtime Guard (LKRG) Debian Package from Source Code and verify software signatures before installation.
|Logo||Host Operating System||Installation Instructions||Note|
|Debian hosts||Follow the instructions below to install from the Whonix ™ repository. ||Do not install LKRG on a Debian host if intending to run VirtualBox (such as Whonix ™) virtual machines (VMs) due to this known bug [archive]. LKRG can be installed inside VirtualBox guest VMs.|
|Non-Qubes-Whonix ™||Follow the installation instructions below.||In Whonix ™, skip the following "Add Whonix ™ repository" step since it is already enabled by default.|
|Qubes OS [archive] Debian based VMs||Follow these LKRG Qubes instructions.||See footnote. |
|Qubes-Whonix ™||Follow these LKRG Qubes-Whonix ™ instructions.||See footnote. |
|Other Linux distributions||LKRG is available for most Linux distributions.||Follow the installation instructions for non-Debian distributions on the official LKRG homepage [archive].|
Add Whonix ™ repository.
The LKRG installation is complete. 
It is recommended to review optional hardening and other entries below, but this is not required.
Note: All the possible configuration changes in this section are optional.
CI- Code Integrity
ED- Exploit Detection
Table: LKRG Configuration Options
|Basics||All sysctl configuration options can be found here [archive].|
|Block Module Loading||Advanced users can block module functionality (|
See also: module loading.
|Current Configuration||To view the current configuration, run.
sudo sysctl -a | grep lkrg
|Hardening - CI Panic - Crash Kernel when Code Integrity Violation||It is possible to further improve the security provided by LKRG, but this can potentially lead to decreased system stability. Users that are willing to make this trade-off can opt-in to the following setting. LKRG developers have not enabled the following sysctl option by default since it can result in kernel panics and system crashes, or occasional false positives (integrity violations and/or exploits are detected when they don't really exist). See the LKRG homepage [archive]. This might be the reason why LKRG developers did not yet enable kernel panic on CI failure by default.
Kernel panic on code integrity
The following command enables kernel panic on CI failure non-persistently until reboot.
sudo sysctl -w lkrg.force_run=1
The following procedure enables this feature persistently after reboot.
(Qubes-Whonix ™: In TemplateVM)
The procedure of enabling CI panic is complete.
|Hardening - UMH Lock||Better do not use for now. Breaks Whonix Firewall. |
|Hide LKRG||Attempts to hide LKRG will not work because this feature is not yet functional; LKRG will still be detected.   |
Once LKRG has been installed, little effort is required since it will protect the kernel without the user's knowledge and/or interaction. However, it is sensible to check that LKRG is running correctly and to monitor system logs for any suspicious entries. Check this entry at a later date for any additional recommendations.
To check systemd journal log for kernel messages by LKRG, run.
sudo journalctl -b | grep lkrg
To keep watching systemd journal log for new LKRG messages, run.
sudo journalctl -b -f | grep lkrg
While performing the commands above, it may be useful to open another console tab and manually run a LKRG integrity check.
sudo sysctl -w lkrg.force_run=1
At this stage a graphical user interface (GUI) is not provided that can proactively inform users who fail to analyze the systemd journal log for relevant LKRG messages. A GUI or popup notification might be developed later on -- help is most welcome.
dpkg -l | grep linux-image
ii linux-image-4.19.0-6-amd64 4.19.67-2+deb10u2 amd64 Linux 4.19 for 64-bit PCs (signed) ii linux-image-amd64
dpkg -l | grep linux-head
ii linux-headers-4.19.0-6-amd64 4.19.67-2+deb10u2 amd64 Header files for Linux 4.19.0-6-amd64 ii linux-headers-4.19.0-6-common 4.19.67-2+deb10u2 all Common header files for Linux 4.19.0-6 ii linux-headers-amd64
sudo modinfo p_lkrg
filename: /lib/modules/4.19.0-6-amd64/updates/dkms/p_lkrg.ko license: GPL v2 description: pi3's Linux kernel Runtime Guard author: Adam 'pi3' Zabrocki (http://pi3.com.pl) depends: usbcore retpoline: Y name: p_lkrg vermagic: 4.19.0-6-amd64 SMP mod_unload modversions parm: p_init_log_level:Logging level init value [1 (alive) is default] (uint)
sudo dkms status
lkrg, 0.7, 4.19.0-6-amd64, x86_64: installed
- Linux Kernel Runtime Guard (LKRG) - Linux Kernel Runtime Integrity Checking and Exploit Detection [archive]
- LKRG Website [archive]
- LKRG Source Code git Repository [archive]
- LKRG Presentation Video [archive]
- LKRG Presentation Slides [archive]
- LKRG Threat Model [archive]
- LKRG Mailing List [archive]
- LKRG Wiki [archive]
Upstream Mailing List Discussions
- LKRG compilation hardening flags, checksec, hardening-check [archive]
- LKRG packagers / downstream wishlist [archive] (signed git commits, signed git tags, version numbers, logo)
- module loading / systemd bug report / suggestion [archive]
- LKRG kills VirtualBox host VMs [archive]
- announcement of this LKRG Debian package on upstream LKRG mailing list [archive]
- LKRG module parameters [archive]
- Compiling LKRG static into the Kernel / Loading LKRG kernel module as early as possible or after other modules? [archive]
- security-misc [archive]: Inspired by the Kernel Self Protection Project (KSPP [archive]). This package implements most if not all recommended Linux kernel settings (sysctl) and kernel parameters set by the KSPP.
- Hardened Malloc [archive]: A hardened memory allocator which can be used with many applications to increase security.
- grub-live [archive]: Boot your existing, installed Debian Host into Live Mode.
- Hardened VM Kernel [archive] (in development): A hardened kernel configuration optimized for virtual machines, see: development discussion [archive].
- System Hardening Checklist
- SecBrowser ™: A Security-hardened, Non-anonymous Browser
- https://www.openwall.com/lkrg/ [archive]
- https://openwall.info/wiki/p_lkrg/Main#What-is-LKRG [archive]
- https://openwall.info/wiki/p_lkrg/Main#Donation [archive]
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=944476 [archive]
- make Linux Kernel Runtime Guard (LKRG) easily available in Qubes [archive]
- Only Intel and amd64 are supported at present, see: https://www.openwall.com/lists/lkrg-users/2018/07/31/3 [archive]
- Note that LKRG versioning is based on upstream's git master branch intention to remain in the "prerelease" stage. Quote Adam Zabrocki https://www.openwall.com/lists/lkrg-users/2019/11/11/1 [archive] We're trying to keep master branch stable and let's say in "prerelease" stage :)
- https://www.openwall.com/lists/lkrg-users/2019/02/19/1 [archive]
Full lock down of the kernel's usermodehelper interface (
lkrg.umh_lock). This might break things if your distro uses UMH to invoke any programs. Two options are available:
0- do NOT lock down the UMH interface fully, but allow to execute only LKRG's whitelisted programs (default)
1- lock down the UMH interface fully
cmd_exec('test -d /proc/sys/lkrg && echo true').to_s.strip.include? 'true'
sudo sysctl -w lkrg.hide=1 lkrg.hide = 1 user@debian-buster-standalone:~$ ls -la /proc/sys/lkrg total 0 dr-xr-xr-x 1 root root 0 Nov 15 03:05 . dr-xr-xr-x 1 root root 0 Nov 15 03:04 .. -rw------- 1 root root 0 Nov 15 03:48 block_modules -rw------- 1 root root 0 Nov 15 03:48 ci_panic -rw------- 1 root root 0 Nov 15 04:18 clean_message -rw------- 1 root root 0 Nov 15 04:19 force_run -rw------- 1 root root 0 Nov 15 04:21 hide -rw------- 1 root root 0 Nov 15 03:48 log_level -rw------- 1 root root 0 Nov 15 03:48 random_events -rw------- 1 root root 0 Nov 15 04:02 smep_panic -rw------- 1 root root 0 Nov 15 03:48 timestamp -rw------- 1 root root 0 Nov 15 04:04 umh_lock user@debian-buster-standalone:~$ lsmod | grep lkrg usbcore 294912 1 p_lkrg user@debian-buster-standalone:~$ sudo sysctl -w lkrg.hide=0 lkrg.hide = 0 user@debian-buster-standalone:~$ lsmod | grep lkrg p_lkrg 217088 -2 usbcore 294912 1 p_lkrg
lkrg.hide) - if built with this optional feature included, LKRG can (un)hide itself from the module list (but it can be detected regardless):
1- hide LKRG (if it is not already hidden)
0- unhide LKRG (if it is not already unhidden)
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