Ttgjyuk

Since kernel version 4.4.0-20, it was enforced that unsigned kernel modules will not be allowed to run with Secure Boot enabled. Because you want to keep Secure Boot, then the next logical step is to sign those modules.

So let's try it.

1. 
   

   Create signing keys

   
   
   

   openssl req -new -x509 -newkey rsa:2048 -keyout MOK.priv -outform DER -out MOK.der -nodes -days 36500 -subj "/CN=Descriptive common name/"
   

   
   
   

   Option: for additional security, skip the -nodes switch, which will ask for a password. Then before moving on to the next step, make sure to export KBUILD_SIGN_PIN='yourpassword'

   
   


2. 
   

   Sign the module (vboxdrv for this example, but repeat for other modules in ls $(dirname $(modinfo -n vboxdrv))/vbox*.ko) for full functionality)

   
   
   

   sudo /usr/src/linux-headers-$(uname -r)/scripts/sign-file sha256 ./MOK.priv ./MOK.der $(modinfo -n vboxdrv)
   

   
   


3. 
   

   Confirm the module is signed

   
   
   

   tail $(modinfo -n vboxdrv) | grep "Module signature appended"
   

   
   


4. 
   

   Register the keys to Secure Boot

   
   
   

   sudo mokutil --import MOK.der
   

   
   
   

   which will ask for a password to use to confirm the import in the next step.

   
   



5. Reboot and follow instructions to Enroll MOK (Machine Owner Key). Here's a sample with pictures. The system will reboot one more time.



6. 
   

   Confirm the key is enrolled

   
   
   

   mokutil --test-key MOK.der
   

   
   

If VirtualBox still does not load, it may be because the module didn't load (sudo modprobe vboxdrv will fix that) or that the key is not signed. Simply repeat that step and everything should work fine.

Resources: Detailed website article for Fedora and Ubuntu implementation of module signing. @zwets for additional security. @shasha_trn for mentioning all the modules.

Additional resource: I created a bash script for my own use every time virtualbox-dkms upgrades and thus overwrites the signed modules. Check out my vboxsign originally on GitHub.

On my system I did the following to make it work:

Run mokutil:

sudo mokutil --disable-validation

Then mokutil asked me to set a password for the MOK Manager.
After rebooting the PC the BIOS showed a dialog to configure the MOK Manager.
I disabled SecureBoot from this dialog, it asked for several characters from the password (ie. enter character (5), etc).

After booting up the vboxdrv modules loaded correctly.

lsmod | grep vboxdrv
vboxdrv 454656 3 vboxnetadp,vboxnetflt,vboxpci

Curiously, mokutil still shows SecureBoot is enabled:

sudo mokutil --sb-state
SecureBoot enabled

You can disable the validation check by

sudo apt install mokutil
sudo mokutil --disable-validation

After that DKMS packages should install.

I got error about vboxdrv after upgrade too. But there was problem with old version (5.0.14) of Oracle VM VirtualBox Extension Pack. I downloaded and installed newer version (5.0.18) of this pack and problem disappeared.

Alright so after a bit of testing I'm pretty sure this is a secure boot issue.

As in if it's enabled then this is thrown:

WARNING: The vboxdrv kernel module is not loaded. Either there is no module
available for the current kernel (4.4.0-21-generic) or it failed to
load. Please recompile the kernel module and install it by sudo /sbin/rcvboxdrv setup

However if secure boot is disabled then virtualbox loads just fine with no errors.

I still have my bios set as UEFI.

I had the same issue today, I had Windows 10 and Ubuntu 15.10 on a dual boot with uefi enabled on Bios (I didn't disable it so I can run the pre-installed Windows).

After upgrading to Ubuntu 16.04 VirtualBox stopped loading my VMs with the same error message:

modprobe: ERROR: could not insert 'vboxdrv': Required key not available

I suspected UEFI issue because while upgrading the installer asked me if I want to disable it, to which I responded No (Because Yes may make my Windows unusable).

What I did is going to Bios and enable support for legacy BIOS boot WITHOUT disabling secure boot.

Virtualbox works fine now.

Update: As @zwets rightly pointed in the comment, enabling legacy modules causes secure boot to be disabled.