GNOME allows users to create ad-hoc wireless connections through the
NetworkManager applet. Wireless connections should be disabled by
adding or setting disable-wifi-create to true in
/etc/dconf/db/local.d/00-security-settings. For example:
[org/gnome/nm-applet]
disable-wifi-create=true
Once the settings have been added, add a lock to
/etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification.
For example:
/org/gnome/nm-applet/disable-wifi-create
After the settings have been set, run dconf update.