[indicators] With phone locked, it's impossible to setup a mobile connection

[Alberto Mardegan]

On the phone, it's possible to connect and disconnect to Wifi networks even when the phone is locked. Unfortunately, the same is not possible for mobile data: in order to setup it or even just to disconnect from it, the user needs to unlock the phone and wait for System Settings to appear.

I propose adding a switch next to each SIM card in the network indicator, to make the experience quicker and more consistent with the Wifi scenario.

------ UX Comment ------

We may consider adding a toggle status for mobile data on the Inidicator panel in the future. However, as Matthew pointed out, we should not allow the setup of a wifi network / change the connection type / carrier, while the phone is locked.

[Matthew Paul Thomas (mpt)]

I doubt that it *should* be possible to set up a Wi-Fi connection with the phone locked. Connecting to an arbitrary network is riskier than merely turning Wi-Fi on/off. If you left your phone unwatched for even a few seconds, a mischievous person could connect you to a network that tracks/records your traffic in ways that the networks you trust do not. And you might not realize this for hours or days.

Letting people connect your phone to arbitrary Wi-Fi networks also increases the attack surface for someone trying to bypass the lock screen. Most obviously, a Wi-Fi network that requires Web sign-up/sign-in should eventually open a mini-browser for that purpose. <https://wiki.ubuntu.com/Networking#captive-portal> So now you'd have to ensure that no vulnerability in the Web view could ever get someone past the lock screen.