screenlocker extension for XLibre

[mahiro21h]

Describe the idea

as you are all aware, screenlockers on x11 have many issues. you can bypass them if you can crash them, windows created with CWOverrideRedirect can appear above their windows etc. this extension would introduce new requests the screenlocker can make to the server to, for example, disable tty switching and create windows for the screenlocker that will always be on top of others. i've been working on it for a while and you can find the reference client here. not perfect or in a state to be merged upstream but it's a good starting point.

It should be done because

problems such as CWOverrideRedirect windows appearing above screenlocker windows are rooted within the xserver itself. the screenlocker can get around this by constantly calling XRaiseWindow(), but it's not possible to get around other issues without potential issues (see this and this too).

What are the alternatives?

none that i am aware of.

Additional context

No response

Extra fields

• I have checked the existing New Ideas, RFCs Of The Core Team, Ideas Soon To Be Addressed and Someday Ideas
• I have read the Contributing Guidelines
• I'd like to work on this idea

[cepelinas9000]

Maybe screen-locker can be solved by having extension which changes screen root window (tried quick hack but didn't work as expected) ? It would have additional benefit as automatically any unrelated grabs will be ignored. As it along lines: you cannot bypass screen saver security if there are no windows at first place :)

[smj-cc]

i can't even begin to imagine what you could do to get around this but i think drawing into the root window is out of the question.

Slightly OT perhaps, but I like the vlock approach: Open a new virtual terminal, switch to it, and lock them all. Ugly, perhaps, but quite effective.

[mahiro21h]

do you have the link to a maintained fork of vlock? it sounds like one of the best approaches, but what would happen if the user is on the tty running the xserver and they leave their device? vlock can't do anything in that case, can it?

[smj-cc]

do you have the link to a maintained fork of vlock?

The current gentoo stable vlock package is built from https://github.com/WorMzy/vlock/archive/3542ef58a2b838cc8294fe82c341fb671c38611b.tar.gz, so unfortunately no. I am not aware of a "maintained" fork.

It's working flawlessly here, and in the absence of alternative, if that should change, then I will maintain it locally if I must.

what would happen if the user is on the tty running the xserver and they leave their device?

What it does here: It times out, then switches to the first unused virtual terminal, disables changing virtual terminals, and waits for the enter key. Upon the enter key, announces who is logged in, and prompts for that user's password. Upon success, it switches back to the previous virtual terminal (usually X here). Upon failure, it prompts for the root password. Upon failure it restarts from the beginning prompting for enter.

[mahiro21h]

very nice i didn't expect that. sadly we have a different version on arch and artix that doesn't have the necessary options to do this.

[smj-cc]

For reference, the ebuild that used that commit of vlock calls itself app-misc/vlock-2.2.3-r2.

Edit 1: And I have a tar file of that commit.

Edit 2: I have just forked https://github.com/mattweidner/vlock, and verified it is a bit image copy of my local tar file.

Edit 3: I note the existence of https://github.com/TragicWarrior/vlock which calls itself 2.2.4, and adds modules "train" and "matrix" as "screensavers". Still evaluating. Changes appear substantial. (he had 5 years to work on it)