Configuring CentOS VirtualBox Guest Additions for Secure Boot

When using Secure Boot on your CentOS system, you may encounter issues when trying to install or run VirtualBox. One common error is the 'Modprobe: ERROR: could not insert 'vboxdrv': Key was rejected by service' message, which indicates that the kernel modules are not signed and cannot be loaded. This issue can be resolved by signing the kernel modules and configuring your system to use them.

To sign kernel modules and enable Secure Boot, you will need to follow a few steps. First, make sure you have installed the akmods package, which is required for secure boot support in Fedora 36 and later versions. You can install this package using the command 'dnf install akmods'.

Next, you will need to add your user to the vboxusers group, which is required for USB passthrough and other features. You can do this by running the command 'usermod -a -G vboxusers '.

Once you have added your user to the vboxusers group, you can sign the kernel modules using the following command:

```

sudo /usr/share/doc/akmods/cureboot

```

This will guide you through the process of signing and installing the kernel modules. Make sure to follow the instructions carefully, as this is a critical step in enabling Secure Boot.

After signing the kernel modules, you can restart your system and try running VirtualBox again. You should no longer encounter any issues with loading the kernel modules.

It's also important to note that when using Secure Boot, it's essential to be careful about who has access to the vboxusers group. Once a user is added to this group, they may have ways to gain root access and run code with elevated privileges. Therefore, only add trusted users to this group.

In addition to signing kernel modules, there are a few other tips and tricks you can use when configuring CentOS VirtualBox Guest Additions for Secure Boot:

* Use the virtualbox-guest-additions package provided by Fedora instead of the official VirtualBox package.

* Install kernel-devel-$(uname -r) package before installing VirtualBox.

* If you're having trouble building the kernel modules, try installing kernel-debug-devel and then rebuilding the modules.

* If you're using a kernel-debug build, make sure to install kernel-debug-devel and not kernel-devel.

By following these steps and tips, you should be able to configure your CentOS system for Secure Boot and use VirtualBox without any issues.

Centos virtualbox guest additions