> On Okt. 14, 2014, 7:02 vorm., Martin Klapetek wrote:
> > Could we possibly get "Suspend" button instead? Suspend stores the session 
> > state into memory and then restores it without any issues (and we lock 
> > screen on wakeup anyway); many times I have found my laptop with locked 
> > screen and I had to unlock, click the suspend button in the panel only to 
> > get it locked again and suspended.
> 
> Martin Gräßlin wrote:
>     I expected this question to come :-) - I'm not sure whether it's a valid 
> use case, at least for laptops. Closing the lid should send it to suspend, 
> the suspend button should still work (if not, we should fix it). So there are 
> already quite some decent ways to get the system to suspend when locked. 
> Especially with lid closing it does what it's supposed to do.
>     
>     In fact the functionality should even be available through the Change 
> Session functionality as that drops you to the login manager where you can 
> suspend. Sure not as comfortable as directly exposing it. But we don't need 
> to expose every option which might make sense ;-)
> 
> Kai Uwe Broulik wrote:
>     Although closing the lid apparently reliably suspends the device, even 
> when locked, my gut makes me not trust it. :/
> 
> Martin Gräßlin wrote:
>     > Although closing the lid apparently reliably suspends the device, even 
> when locked, my gut makes me not trust it. :/
>     
>     At least my notebook(s) have a visible LED indicating it is in sleep mode.
> 
> Martin Klapetek wrote:
>     There are still usecases however where either the user does not want/need 
> to close the lid and/or sets his laptop to not suspend on the lid close 
> (personally I have that disabled when on charger). Plus there is the whole 
> non-laptop world. It's not about exposing every option that makes sense, it's 
> about replacing one senseless with one that makes more sense ;)
> 
> Martin Gräßlin wrote:
>     > It's not about exposing every option that makes sense, it's about 
> replacing one senseless with one that makes more sense ;)
>     
>     I don't see it that way. The option got added in a strange way shortly 
> before the 5.0 release with the maintainers of the screenlocker not having a 
> chance to review it (let's say it simple: if I would have reviewed the code, 
> it would not have gone in, in the first place). So I'm comparing to the last 
> state where it was working which is 4.11 and there the screen locker did not 
> expose such an option and I want to go back to that working state. Let's look 
> from there whether it's a valid option to expose the suspend option and not 
> from the broken state.
>     
>     To me it's not a valid use case to expose suspend in the lock screen. To 
> a certain degree it circumvents security. Suspend/Hibernate is allowed on a 
> per-user logged in base. That's implemented by checking whether 
> suspend/hibernate is supported at runtime. By exposing it in the screenlocker 
> it circumvents the check. A not logged in user (or a user who is not allowed 
> to supsend in his session) is able to suspend (multi user system just needs 
> to switch to a logged session which allows suspend). Thus I think from a 
> security perspective the option may not be there in the first place.
> 
> Martin Klapetek wrote:
>     Oh come on, that's hardly any security circumvention. By that logic we 
> should not show battery state, current user's date/time, user name and user 
> picture in the lock screen either because it's exposing things which other 
> users might have restricted access to.
>     
>     Plus you said in the very first comment that it's possible to go around 
> this to the login screen and from there anyone can suspend...
> 
> Martin Gräßlin wrote:
>     > Plus you said in the very first comment that it's possible to go around 
> this to the login screen and from there anyone can suspend...
>     
>     yes and no. In a multi-user system you can of course configure the system 
> in a way to not allow suspend/hibernate from login manager.
>     
>     It all boils down to: why do we go all the hassle to check whether this 
> options should be enabled from a security point of view, when we allow it for 
> not logged-in users. If we go for allow for not logged in users, we can 
> remove quite a decent amount of code...
> 
> Kai Uwe Broulik wrote:
>     Having a suspend button is a security issue but closing the lid, which 
> causes it to suspend, is not?
> 
> Martin Gräßlin wrote:
>     > Having a suspend button is a security issue but closing the lid, which 
> causes it to suspend, is not?
>     
>     no, as that is controlled by logind. If the system is configured to not 
> allow it, logind won't suspend the system if the lid closes.

So, the button should also honor that policy?


- Kai Uwe


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/120577/#review68345
-----------------------------------------------------------


On Okt. 14, 2014, 5:41 vorm., Martin Gräßlin wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/120577/
> -----------------------------------------------------------
> 
> (Updated Okt. 14, 2014, 5:41 vorm.)
> 
> 
> Review request for Plasma and Aleix Pol Gonzalez.
> 
> 
> Repository: plasma-workspace
> 
> 
> Description
> -------
> 
> Logging out from the locked screen is impossible. Logging out means
> interaction with the session due to the session manager. The session
> manager asks all applications to quit and applications are allowed to
> ask for example saving changes. The session manager stopps the
> logout in this case and asks the window manager to focus this window
> and the session manager will only continue the logout once the
> application resolved the situation. At any time in this process the
> user is still able to abort the logout!
> 
> Switching to the application which needs interaction is impossible,
> though as the screen is still locked. The result is a seemingly
> frozen system as the logout cannot continue and there is no indication
> what is going on.
> 
> Of course the lock screen cannot unlock the session for the logout as
> that would circumvent the security. If the lock screen would unlock
> one would just have to click the button and abort the logout really
> fast to have the system unlocked. So this is clearly not an option.
> 
> The result is: we cannot implement this functionality in a working
> and secure manner, so it's better to remove it.
> 
> 
> Diffs
> -----
> 
>   lookandfeel/contents/lockscreen/LockScreen.qml 
> 7d730cf1ebd8241dfe1c00a2bef86ec4a3f0212d 
> 
> Diff: https://git.reviewboard.kde.org/r/120577/diff/
> 
> 
> Testing
> -------
> 
> run kscreenlocker_greeter --testing and locked the screen - button is gone.
> 
> 
> Thanks,
> 
> Martin Gräßlin
> 
>

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