subscription-manager currently does not have a way to get credentials
(username, password, activation keys, organization ID) in a secure way:
the existing command line parameters can be easily spotted when running
a process listing while 'subscription-manager register' runs.
There is a D-Bus service, which is used by e.g. cockpit and Anaconda to
interface with RHSM (at least for registration and common queries).
Try to perform the registration using D-Bus, in a way very similar to
the work done in convert2rhel [1] (with my help):
- try to do a simple signal test to check whether the system bus works;
inspired by the login in the dconf module
- pass most of the options as registration options; for the few that are
not part of the registration, execute 'subscription-manager' manually
- add quirks for differently working (or not) registration options for
the D-Bus Register*() methods depending on the version of RHEL
- 'subscription-manager register' is used only in case the signal test
is not working; silent fallback in case of D-Bus errors during the
registration is not done on purpose to avoid silent fallback to a less
secure registration
[1] https://github.com/oamg/convert2rhel/pull/540/
