wrong permissions for /etc/ceph/client.radosgw.gateway

Detailed bug description:
Here is current ceph config directory:
root@node-5:~# ls -l /etc/ceph/
total 32
-rw------- 1 root root 127 Jul 28 08:56 ceph.client.admin.keyring
-rw------- 1 cinder cinder 193 Jul 28 09:09 ceph.client.backups.keyring
-rw------- 1 root root 113 Jul 28 08:56 ceph.client.bootstrap-osd.keyring
-rw------- 1 glance glance 167 Jul 28 09:09 ceph.client.images.keyring
-rw------- 1 cinder cinder 191 Jul 28 09:09 ceph.client.volumes.keyring
-rw-r--r-- 1 root root 1186 Jul 28 09:05 ceph.conf
-rw------- 1 root root 120 Jul 28 09:05 client.radosgw.gateway
-rw------- 1 root root 92 May 21 01:41 rbdmap

"client.radosgw.gateway" is owned by root. so "systemctl restart <email address hidden>" fails with these errors:
root@node-5:~# fgrep 'Permission denied' /var/log/*
/var/log/daemon.log:<30>Jul 28 09:05:34 node-5 radosgw[15475]: 2016-07-28 09:05:34.178617 7f5a5d808a00 -1 auth: unable to find a keyring on /etc/ceph/client.radosgw.gateway: (13) Permission denied
/var/log/daemon.log:<30>Jul 28 09:05:34 node-5 radosgw[15582]: 2016-07-28 09:05:34.641089 7f693b096a00 -1 auth: unable to find a keyring on /etc/ceph/client.radosgw.gateway: (13) Permission denied
/var/log/daemon.log:<30>Jul 28 09:05:34 node-5 radosgw[15608]: 2016-07-28 09:05:34.991811 7ff7f5bf6a00 -1 auth: unable to find a keyring on /etc/ceph/client.radosgw.gateway: (13) Permission denied
/var/log/daemon.log:<30>Jul 28 09:05:35 node-5 radosgw[15702]: 2016-07-28 09:05:35.256925 7f002b8eaa00 -1 auth: unable to find a keyring on /etc/ceph/client.radosgw.gateway: (13) Permission denied
/var/log/daemon.log:<30>Jul 28 09:05:35 node-5 radosgw[15732]: 2016-07-28 09:05:35.639048 7f8959727a00 -1 auth: unable to find a keyring on /etc/ceph/client.radosgw.gateway: (13) Permission denied
/var/log/debug:<15>Jul 28 09:05:34 node-5 radosgw: 2016-07-28 09:05:34.178617 7f5a5d808a00 -1 auth: unable to find a keyring on /etc/ceph/client.radosgw.gateway: (13) Permission denied
/var/log/debug:<15>Jul 28 09:05:34 node-5 radosgw: 2016-07-28 09:05:34.178628 7f5a5d808a00 0 librados: client.radosgw.gateway initialization error (13) Permission denied
/var/log/debug:<15>Jul 28 09:05:34 node-5 radosgw: 2016-07-28 09:05:34.641089 7f693b096a00 -1 auth: unable to find a keyring on /etc/ceph/client.radosgw.gateway: (13) Permission denied
/var/log/debug:<15>Jul 28 09:05:34 node-5 radosgw: 2016-07-28 09:05:34.641111 7f693b096a00 0 librados: client.radosgw.gateway initialization error (13) Permission denied
/var/log/debug:<15>Jul 28 09:05:34 node-5 radosgw: 2016-07-28 09:05:34.991811 7ff7f5bf6a00 -1 auth: unable to find a keyring on /etc/ceph/client.radosgw.gateway: (13) Permission denied
/var/log/debug:<15>Jul 28 09:05:34 node-5 radosgw: 2016-07-28 09:05:34.991823 7ff7f5bf6a00 0 librados: client.radosgw.gateway initialization error (13) Permission denied
/var/log/debug:<15>Jul 28 09:05:35 node-5 radosgw: 2016-07-28 09:05:35.256925 7f002b8eaa00 -1 auth: unable to find a keyring on /etc/ceph/client.radosgw.gateway: (13) Permission denied
/var/log/debug:<15>Jul 28 09:05:35 node-5 radosgw: 2016-07-28 09:05:35.257781 7f002b8eaa00 0 librados: client.radosgw.gateway initialization error (13) Permission denied
/var/log/debug:<15>Jul 28 09:05:35 node-5 radosgw: 2016-07-28 09:05:35.639048 7f8959727a00 -1 auth: unable to find a keyring on /etc/ceph/client.radosgw.gateway: (13) Permission denied
/var/log/debug:<15>Jul 28 09:05:35 node-5 radosgw: 2016-07-28 09:05:35.639057 7f8959727a00 0 librados: client.radosgw.gateway initialization error (13) Permission denied

The proper owner and group are "ceph".

Operation system: Ubuntu 16.04
Package versions:
root@node-5:~# dpkg -l | grep ceph
ii ceph 10.2.0-0ubuntu0.16.04.2 amd64 distributed storage and file system
ii ceph-common 10.2.0-0ubuntu0.16.04.2 amd64 common utilities to mount and interact with a ceph storage cluster
ii libcephfs1 10.2.0-0ubuntu0.16.04.2 amd64 Ceph distributed file system client library
ii python-cephfs 10.2.0-0ubuntu0.16.04.2 amd64 Python libraries for the Ceph libcephfs library
root@node-5:~# dpkg -l | grep rados
ii librados2 10.2.0-0ubuntu0.16.04.2 amd64 RADOS distributed object store client library
ii libradosstriper1 10.2.0-0ubuntu0.16.04.2 amd64 RADOS striping interface
ii python-rados 10.2.0-0ubuntu0.16.04.2 amd64 Python libraries for the Ceph librados library
ii radosgw 10.2.0-0ubuntu0.16.04.2 amd64 REST gateway for RADOS distributed object store