UEFI Secure Boot Support


The feature is in an early stage of adoption and not all distributions could be supported.

This new functionality lets KernelCare work on systems with secure boot set up in their UEFI firmware. We are going to add a public certificate to the MOK (Machine Owner Keys) database that KernelCare will use to sign modules.

The latest KernelCare package contains a public certificate and will be available in the /usr/libexec/kcare/kernelcare_pub.der. For older versions, it could be downloaded from the https://patches.kernelcare.com/kernelcare_pub.der to that location.

For example:

curl -o /usr/libexec/kcare/kernelcare_pub.der https://patches.kernelcare.com/kernelcare_pub.der

  1. Use mokutil as root to add this new MOK to the UEFI firmware.
$ mokutil --import /usr/libexec/kcare/kernelcare_pub.der
 input password:
 input password again:

It doesn't have a MOK password, and mokutil will ask you to create one. The password is temporary and will be used on the next boot.

  1. Reboot your machine to enter the MOK manager EFI utility.

First, go down to the 'Enroll Mok':

Then the firmware gives you the option of viewing the new MOK or continuing. Let's continue.

It then asks you to confirm the enrollment.

Then enter the password you used when running the mokutil --import.

Finally, the firmware will ask you to reboot.

  1. Verify the key has been loaded by finding it in the output of the following command:
$ mokutil --list-enrolled | egrep -i 'SHA1|Issuer'

In some cases an enrolled key will not be shown but could be verified by following command:

$ dmesg | grep -i 'cloud linux' 
[   0.722149] EFI: Loaded cert 'Cloud Linux Software, Inc: Kernel Module Signing Key: 12ff0613c0f80cfba3b2f8eba71ebc27c5a76170' linked to '.system_keyring'

That's it. Now you should be able to apply patches as usual.

To get more information about signing kernel modules for secure boot, see https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/managing_monitoring_and_updating_the_kernel/signing-kernel-modules-for-secure-boot_managing-monitoring-and-updating-the-kernel.