Unix & Dbus mediation support

[roddhjav]

Sum up

• unix mediation is (finally) be enforced outside of Ubuntu. It requires apparmor 5.0, abi 5.0 and kernel 6.17+.
• Using unix mediation as a base, dbus mediation is also coming.

State

• Add/Enforce thousands of dbus rules to various profiles
• In preparation of this, they have been major changes in dbus rules in the past months.
• Considerable security improvement (you can do everything with dbus)
• Very strict mediation already in place, to the point we may have to provide a default mode that is less strict.

Problem

• Some bugs: https://gitlab.com/apparmor/apparmor/-/issues/565
• Some non Ubuntu specific rule may be missing, but overall integration is already very good.
• Missing rules can break profiles. Therefore, extra care must be taken. See 7345968, 5c673ef