I would like to introduce a planed improvement within the area of
applicability of rules / groups / profiles for specific platforms.
I would like to ask you to provide feedback, especially with
regards to content authoring experience.
Currently, you can use the "platform:" keyword to mark a part of SSG content as applicable for a given platform. This can be done in scope of profile, group and rule.
Notice that these three scopes are listed in the specific order, as they go in hierarchy from profile (highest level) to rule (lowest level).
Currently, platforms propagate through this hierarchy. So if you specify that some profile is applicable only to "machine" platform, all rules within this profile will be applicable only to the "machine" platform. The same is true for groups; all rules within a group will inherit a platform specified for the group.
These platforms are connected with implicit AND. Please note that currently you can specify only ONE platform per profile / group / rule.
But what if you want to make rule applicable to combination of platforms? For example there is a rule for ntpd OR chrony:
This is currently not possible.
Or what if you want to make rule applicable to conjunction of platforms, e.g. rule should be applied if Grub2 is installed and UEFI is used.
This is currently possible, but it involves creating groups and
abusing the fact that group applicability is connected with AND
with rule applicability (XCCDF specification).
We would like to change this and make applicability more
flexible. Changes are planed for profile, group and rule
The first change should allow to define multiple independent platforms. A new keyword "platforms" will be added. It will expect a list of platforms. All platforms in the list will be connected with "OR". For example, for the rule about ntpd and chrony, you could specify:
The change is backward compatible, it is still possible to specify single platform through
This change is already being implemented here:
We chose this approach because it is easy to implement. XCCDF specification already allows to specify multiple platforms per group/profile/rule and they are implicitly connected with OR.
The next step will be implementing of support for specification of multiple combined platforms (joining platforms with AND).
The specification would utilize the previous syntax but additionally it could include a special character, e.g. &.
To specify applicability only for cases when Grub2 and UEFI are present at the same time, it could be:
- grub2 & uefi
To specify platform for Zipl or Grub2 bootloader but only if UEFI is used, it could be:
- zipl & uefi
- grub2 & uefi
This change would start using CPE applicability language to define new platforms which would be created at build time.
What do you think about this initiative? Awaiting your feedback.