Hi all,

thank you for interest in improving our content, that's always great to see.

I would just like to clarify information postet by Gabe because as far as I know, Grub2 config files are not structured as described.

The /boot/grub2/grubenv is a environment block file, described here:

https://www.gnu.org/software/grub/manual/grub/grub.html#Environment-block

It is not a full Grub2 configuration file, it is a file with limited size to configure some environment variables. Howerver, it is parsed together with the main configuration file so it should be checked.

The main configuration file grub.cfg is placed either:

in /boot/grub2/grub.cfg in case it is BIOS system

- in /boot/efi/EFI/redhat/grub.cfg in case of UEFI system

as described here:

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/ch-working_with_the_grub_2_boot_loader#sec-Introduction_to_GRUB_2

Fedora has its own UEFI directory.

Additionally, the check checks also for contents of /etc/default/grub because Grub2 configuration can be generated by grub2-mkconfig from this file.

I think that extending the template with a parameter like technology = uefi|bios is an interesting idea. Currently, we do not check for the grub.cfg file in case of UEFI, at least not in this template.

Vojta








Dne 20. 07. 20 v 18:38 Gabe Alford napsal(a):


On Wed, Jul 15, 2020 at 2:28 AM Andy Coates <andy.coates@gmail.com> wrote:
Hi All,

First I'm jumping in the deep end with this - I've only just discovered the ComplianceAsCode/content repo and whilst loving the design and flexibility, as a newbie it is very daunting to ingest how all the rules are generated and interact, but it is very logical as I start to understand it more.

I'm currently looking at the linux rule grub2_audit_argument which uses shared/templates/template_OVAL_grub2_bootloader_argument to create the OVAL definitions.  The problem is the template hardcodes the grub path to /boot/grub2/grub.cfg, but with UEFI, just like the rule documentation warns, it will be /boot/efi/EFI/redhat/grub.cfg or /boot/efi/EFI/fedora/grub.cfg.  So the rule describes what should be checked and which files to audit for both BIOS and UEFI versions, but the actual criteria check only supports the BIOS/default path.

So I was curious what the approach would be for adding support to this.  I see other OVAL tests that use a shared OVAL check to test (extend) if the system is UEFI or not, and pass those that aren't - and will then have a counterpart rule just for UEFI, so both rules can exist and be checked.  As the grub2_audit_argument rule is using a template, the template isn't UEFI aware, and doesn't create two rules for both UEFI and non-UEFI that could use the shared extended OVAL check for UEFI.  There are conditionals in the template for RHEL or others, to determine what content should be checked, but I can't see how you could use a conditional for UEFI path or not.   If I create two rules that use the same template and pass in different arguments (e.g. UEFI or not), then the test names duplicate and the build complains.  These are just the things I've thought about uplifting from my limited experience.

What would be right way of adding in that path support for UEFI based systems?  I'm also surprised others wouldn't notice/report this, so perhaps I'm misunderstanding something.

The template should be checking /etc/default/grub and /boot/grub2/grubenv. 
/boot/grub2/grubenv should be a symbolic link to either the non-UEFI configuration file /boot/grub2/grub.cfg or the EFI configuration file /boot/efi/EFI/redhat/grub.cfg which should eliminate the need to check either non-UEFI or UEFI grub configuration files.
If this is not the case, a bug should be opened.
 

Thanks!
Andy.
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