change applicability of rules configuring idle session timeouts

[vojtapolasek]

Description:

• create new OVAL definition checking if installed OS is RHEL
• create three new platforms checking if RHEL >= 8.7, if RHEL <=8.5 and RHEL == 9.0
• use these platforms to limit applicability of logind_session_timeout and sshd_set_idle_timeout

Rationale:

The Systemd feature which can configure session idle timeout is not present in all RHEL releases, therefore the rule does not apply in some cases. To be exact, the feature works only in 9.1 and up and 8.7 and up.
Also the SSH configuration used by sshd_set_idle_timeout has effect only in some cases. It works only up to 8.5.

Testing hints:

• build RHEL 8 and RHEL 9 content
• test the following (you can artifically modify RHEL version by editing the ID within /etc/os-release):
• logind_session_timeout should apply on 8.7 and higher with exception of 9.0
• sshd_set_idle_timeout should be applicable on 8.5 and lower.
• consequently, none of these rules would be applicable on 8.6.

[github-actions]

Start a new ephemeral environment with changes proposed in this pull request:

Fedora Environment

Oracle Linux 8 Environment

[Mab879]

While this covers the spirit of RHEL-08-010201 it not the letter of RHEL-08-010201, so I don't know if we want to add this stigid yet.

[vojtapolasek]

I agree. I removed also CIS references because I think the reason is the same. What do you think @marcusburghardt ?

[Mab879]

After a review of the CIS benchmarks, I would agree with pulling the CIS references.

[marcusburghardt]

I also agree to not include CIS reference here.

[vojtapolasek]

@Mab879 @marcusburghardt @yuumasato @matejak could you please review and eventually merge this? I would like to get it into the release, plus there will be one more small PR which depends on this one.