Using KVM and VirtualBox on the same machine.

Summary:

VirtualBox doesn’t run while KVM modules are loaded. Here I will show you how you can get around this, without rebooting or uninstalling either one, as well as how to automate it so that you can just launch the applications with their respective modules loaded.

Intro:

As everyone who has an interest in IT knows, virtualization is pretty darn useful. Not only is it the foundation of cloud computing, but it allows you to quickly spin up different VMs for development and testing,or have a sandboxed environment for malware analysis, or a pre-configured box for pentesting that can be discarded after the engagement.

It also fantastic for studying IT, as you can have a virtual lab environment, as you no longer have to purchase a lot of expensive hardware. Building your own lab is great practice, and thera are a bunch of labs that people have created for you to download to practice different techniques.

For hacking you can download labs from VulnHub,and DVWA,Metasploitable 2 & 3,OWASP Juice Shop, and GOAD are great as well.

Scenario:

So I wanted to do the aforementioned GOAD, a lab consisting of five VMs. Orange-Cyberdefense has made a python script for the setup, which can install it on different hypervisors, which is very cool. While a proxmox server is on the wishlist, I have to install locally on my laptop, so I am limited to using VirtualBox. I normally use KVM/QEMU, but when given such a cool lab for free, who am I to complain?

Problem:

After installing and trying to run a vm in VirtualBox I was greeted with the error message:

Failed to open a session for the virtual machine ...
VirtualBox can't operate in VMX root mode. Please disable the KVM
kernel extension, recompile your kernel and reboot
(VERR_VMX_IN_VMX_ROOT_MODE).

Not cool. But as it turns out, there’s no need to recompile, or to reboot for that matter.

As it turns out, VirtualBox doesn’t play well with KVM and won’t run if the KVM modules are loaded. KVM, on the other hand, has no problem running with the VirtualBox modules loaded.

Solution:

In Linux we can remove or insert kernel modules using modprobeor rmmod/insmod, and when installing VirtualBox you even get a script, vboxreload, to load the modules (at least on Arch).

first we can check the kvm modules using lmod | grep kvm, which shows two modules loaded: kvm and kvm_intel (since I have an Intel CPU).

if we unload the modules using either sudo modprobe --remove kvm_intel kvm or sudo rmmod kvm_intel kvm, and then load the VirtualBox modules with sudo vboxreload. If you don’t have the shellscript then you can use modprobe to load vboxdrv, vboxnetadp & vboxnetflt.

Now you’ll find that VirtualBox will run. If you then want to use KVM you’ll have to load the modules again. You can do this with either modprobe or insmod, but note that while modprobe will look in /usr/lib/modules, with insmod you have to specify the file yourself.

The module will be located in a directory named after the current version of your kernel, so to avoid having to update the script every time you update the kernel I recommend you use `uname -r` (note the backticks) in the pathname:

/sbin/insmod /lib/modules/`uname -r`/kernel/arch/x86/kvm/kvm.ko.zst

Automation:

Having to do this manually every time seem a bit tedious though, so we can automate it. If you launch the applications from the terminal then you could do one script for each application, which insert/remove modules and launch the app, and make aliases for them and you’re good to go.

I, however, prefer to use wofi, so I have to do a couple of extra steps. Since I’m not launching from a terminal I need to add my scripts to the sudoers file, but since I want to launch the applications from my user and I don’t want to give a general NOPASSWORD for loading kernel modules I split the scipts into a loading and a launching script.

vboxLoad.sh:

#!/bin/bash
/sbin/rmmod kvm_intel kvm
/usr/bin/vboxreload

vboxLaunch.sh:

#!/bin/bash
sudo /home/tuxpad/scripts/vbLoad.sh
/usr/bin/virtualbox

kvmLoad.sh:

modprobe --remove vboxnetadp vboxnetflt vboxdrv
modprobe kvm_intel kvm

kvmLaunch.sh:

sudo /home/tuxpad/scripts/kvmLoad.sh
/usr/bin/virt-manager

Then I added the scripts to the sudoers file: tuxpad ALL=(root) NOPASSWD: /home/tuxpad/scripts/vbLoad.sh,/home/tuxpad/scripts/kvmLoad.sh

And finally I edited /usr/share/applications/virtualbox.desktop (and virt-manager.desktop) so that wofi uses the the scripts to launch the applications.

Now I can Launch both VirtualBox and Virt-manager from wofi and they’ll have the appropriate modules loaded when I do so.