[Solved] Lightdm security

wycero · 2020-07-29 01:22:09

I'm concerned about security these days, and I've heard that x11 is unsafe. Is it safe to use lightdm and lightdm-gtk-greeter while logging in a gnome session on wayland?

Last edited by wycero (2020-07-29 06:32:50)

Trilby · 2020-07-29 01:40:45

wycero wrote:

I've heard that x11 is unsafe.

From who? In what way?

wycero wrote:

Is it safe to use lightdm and lightdm-gtk-greeter while logging in a gnome session on wayland?

Safe from what? It's likely safer to use no DM at all and just start your session either from the tty or a systemd service.

wycero · 2020-07-29 04:34:18

Is it possible for a random program to connect to the X server when lightdm is running? If so, can it steal information from lightdm?

GaKu999 · 2020-07-29 04:53:01

wycero wrote:

Is it possible for a random program to connect to the X server when lightdm is running? If so, can it steal information from lightdm?

Probably it could happen, but this is linux...and what you describe it’s called malware...

If something does that kind of fishy stuff on your system it’s likely that you are the one to blame for running obscure closed source binaries that came from nowhere or curl somescript | sh...

Anyways, can it even be useful information? There are by far greater concerns in security, and if you are worried by X as root you may use xorg-xinit or sx...

It’s healthy to remember security but you are going to be unhappy if you become paranoid...

GaKu999 · 2020-07-29 04:57:59

*sigh* since this happened might as well give it good use...

If you feel that you need security you may follow this wiki page:
https://wiki.archlinux.org/index.php/Security

You the calmly evaluate your needs for security and follow whatever suits you best.

The xinit wiki page:
https://wiki.archlinux.org/index.php/Xinit

And for those scared by inetutils there’s the sx package.

That one does not have it’s own wiki page but it’s so simple that it’s man page is enough...

And remember, the most important advice of them all is to not overcomplicate things, a system shouldn’t be secured to the point it’s unusable...

Last edited by GaKu999 (2020-07-29 05:30:17)

seth · 2020-07-29 06:16:37

1) Every process with root permissions will be able to grab your input - lightdm, X11, wayland, the linux console only, …
2) If I manage to preload a custom library into your process (eg. changing it's environment to LD_PRELOAD it) I can do worse than reading your input - lightdm, X11, wayland, the linux console only, …
3) What you specifically want to know is:
a) which processes have access to the X11 server while lightdm is running
b) whether lightdm *mitigates* attack vectors by grabbing the keyboard (preventing other X11 clients from intercepting the input)

For a quick test, running

DISPLAY=:0 xdotool key "XF86LogGrabInfo"

from a different VT will dump the active and passive grabs to the Xorg log or throw an error because you can't access the server.

ondoho · 2020-07-29 11:56:32

wycero wrote:

Is it possible for a random program to connect to the X server when lightdm is running? If so, can it steal information from lightdm?

What machine is this random program running on, and how does it connect to your machine?

Arch Linux

#1 2020-07-29 01:22:09

[Solved] Lightdm security

#2 2020-07-29 01:40:45

Re: [Solved] Lightdm security

#3 2020-07-29 04:34:18

Re: [Solved] Lightdm security

#4 2020-07-29 04:53:01

Re: [Solved] Lightdm security

#5 2020-07-29 04:57:59

Re: [Solved] Lightdm security

#6 2020-07-29 06:16:37

Re: [Solved] Lightdm security

#7 2020-07-29 11:56:32

Re: [Solved] Lightdm security

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