external USB hard drive mount permissions

[Federico Beffa <beffa@ieee.org>]

Hi,

I'm using Debian Stretch with Gnome. When I plug-in an external USB
hard drive (ext4) it gets automatically mounted at /media/beffa/label.
However, the drive is read-only for the user owning the Gnome shell
(beffa). I've tried adding default ACL entries to /media/beffa as
follows

# file: .
# owner: root
# group: root
user::rwx
user:beffa:rwx
group::r-x
mask::rwx
other::r-x
default:user::rwx
default:user:beffa:rwx
default:group::r-x
default:mask::rwx
default:other::r-x

but the device is still only writable by root.

How can I tell the system to make it writable for the user owning the
Gnome session or even everybody?

Thanks for your help!
Fede