[Focal] Confined applications cannot auto-activate media-hub-service.
So, certain policy groups in apparmor-easyprof-ubuntu have the rule that reads:
dbus (receive, send)
bus=session
path=/com/lomiri/MediaHub/Service{,/**}
peer=(label="{unconfined,/usr/bin/media-hub-server}"),
And since D-Bus starts checking for AssumedAppArmorLabel
in [1], it will not match and client will be denied. Thus, the D-Bus .service file need to have
AssumedAppArmorLabel=/usr/bin/media-hub-server
in it.
[1] https://gitlab.freedesktop.org/dbus/dbus/-/commit/dc25979eb
Edited by Ratchanan Srirattanamet