Description of problem:
SELinux is preventing gdbus from 'write' accesses on the fifo_file /run/systemd/inhibit/3.ref.

*****  Plugin catchall (100. confidence) suggests   **************************

If you believe that gdbus should be allowed write access on the 3.ref fifo_file by default.
Then you should report this as a bug.
You can generate a local policy module to allow this access.
Do
allow this access for now by executing:
# ausearch -c 'gdbus' --raw | audit2allow -M my-gdbus
# semodule -X 300 -i my-gdbus.pp

Additional Information:
Source Context                system_u:system_r:init_t:s0
Target Context                system_u:object_r:systemd_logind_inhibit_var_run_t
                              :s0
Target Objects                /run/systemd/inhibit/3.ref [ fifo_file ]
Source                        gdbus
Source Path                   gdbus
Port                          <Unknown>
Host                          (removed)
Source RPM Packages           
Target RPM Packages           
Policy RPM                    selinux-policy-3.14.1-32.fc28.noarch
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Enforcing
Host Name                     (removed)
Platform                      Linux (removed) 4.17.2-200.fc28.x86_64 #1 SMP Mon
                              Jun 18 20:09:31 UTC 2018 x86_64 x86_64
Alert Count                   1
First Seen                    2018-06-26 16:06:16 PDT
Last Seen                     2018-06-26 16:06:16 PDT
Local ID                      dfaade28-5d6d-4954-b8fb-26a9f2a1424f

Raw Audit Messages
type=AVC msg=audit(1530054376.797:157): avc:  denied  { write } for  pid=1038 comm="gdbus" path="/run/systemd/inhibit/3.ref" dev="tmpfs" ino=26013 scontext=system_u:system_r:init_t:s0 tcontext=system_u:object_r:systemd_logind_inhibit_var_run_t:s0 tclass=fifo_file permissive=0


Hash: gdbus,init_t,systemd_logind_inhibit_var_run_t,fifo_file,write

Version-Release number of selected component:
selinux-policy-3.14.1-32.fc28.noarch

Additional info:
component:      selinux-policy
reporter:       libreport-2.9.5
hashmarkername: setroubleshoot
kernel:         4.17.2-200.fc28.x86_64
type:           libreport

Potential duplicate: bug 1593819