On Wed, Jun 24, 2020 at 4:55 AM Iñaki Ucar <iucar@fedoraproject.org> wrote:

I need some help from a SELinux guru. TL;DR, I've developed a small
service. An app talks to this service, the service does some stuff
and, in the meanwhile, it reports the progress to the app user by
writing some messages into the stderr (/proc/<pid>/fd/2) of that app.

Search on YouTube for one of Thomas Cameron's presentations entitled "SELinux for Mere Mortals" -- I've found his presentations to be very informative and approachable.