Enhancing X11 Application Security with LXC

(dobrowolski.dev)

57 points by shirozuki8 hours ago

9 comments

mid-kid5 hours ago
For an article written late last year I hoped for a little more awareness of how massive a security hole granting full, unfiltered access to the X11 server is. Granted, any sandboxing is better than none, but firefox is one of the few apps that already sandboxes itself really well, and with a blog title like that it might be good to touch upon things like nested X servers such as Xephyr.
- BobbyTables29 minutes ago
 Yeah, sadly Firefox and Chrome want almost full privileges so that they can sandbox themselves.X itself always bothers me. Xeyes is cute until one considers the practical implications…
ElijahLynn40 minutes ago
Is X11 going to be like IE6. Still around in another 10 years after it was intended to be deprecated across all major distros (2025/2026).
- toenail1 minute ago
 Is wayland going to be aroud in another 10 years, or it it the new pulseaudio?
- shevy-java16 minutes ago
 I don't think it is "just around" - it is actively maintained still:<a href="https://github.com/X11Libre/xserver" rel="nofollow">https://github.com/X11Libre/xserver</a>In the end Red Hat failed to kill off X11. Let's see what happens next. The GTK devs already rejected patches for maintaining the toolkit further for the xorg platform, following their "GTK5 will no longer support x11" agenda. Would be kind of great to have a universal GUI toolkit that would work rather than have toolkits controlled de-facto by private companies who just willy-nilly throw out support for this or that platform at their own selfish discretion. Though, someone else now helps maintain gtk2, though most of the patches are in regards to fixing bugs, ensuring that it can be compiled and so forth. <a href="https://git.devuan.org/Daemonratte/gtk2-ng" rel="nofollow">https://git.devuan.org/Daemonratte/gtk2-ng</a>
waynecochran52 minutes ago
I wish I lived in a world were you didn't have to sign contracts, lock your doors, or have X11 security. It is so fun to run xmeltdown a new user's display.
sedatk37 minutes ago
Putting apps in a container sounds like a great idea until you need to access your files.
ChocolateGod3 hours ago
Correct me if I'm wrong, but passing through the X socket gives a giant sandbox escape as any application can control/see any other application, including a root terminal in a GUI app.
- Chu4eeno3 hours ago
 No, X11 supports pretty detailed per-application access control, similar to selinux (XACE).The author of the phoenix x server has blogged about it, iirc.
 - ChocolateGod2 hours ago
 > XACEWhich is configured by default on what distros?
 - lotharcable1 hour ago
 Nowhere (and everywhere).It is my understanding that XACE doesn't actually provide any security features itself. It just provides the "hooks" to implement security extensions. Like LSM feature in Linux kernel. You have to install a additional X11 extension to do something useful with it.So the most common X11 security extension is going to be xcsecurity which enables the SECURITY extension. It allows a course permission model were applications can be designated as "Trusted" or "Untrusted". That is going to show up in many Linux distributions.However all applications default to "trusted" because if they are untrusted they tend to cause lots of other annoying problems and crashes a lot of apps, apparently.In practice the only place it shows up is if you are using "ssh -X". That uses the security extension by default. Which is why there is also a "ssh -Y" that disables it for applications that it breaks.This sort of thing is why to fix X11 security you have to give up backwards compatibility and create a new X version.Oh, wait, that is what the X developers did with Wayland.
 - shevy-java11 minutes ago
 > that is what the X developers did with WaylandThis is rather incomplete. For instance, gtk devs already threw out tons of old code in GTK4. Wayland also has fewer features than xorg; and there are also fewer choices available. I noticed this with regards to WMs/DEs. I am not even going to issues wayland has with regards to certain video graphics - that's another not mentioned issue here.You are trying to pick individual cherries.> This sort of thing is why to fix X11 security you have to give up backwards compatibility and create a new X version.I don't think so: <a href="https://github.com/X11Libre/xserver" rel="nofollow">https://github.com/X11Libre/xserver</a>Let's have a look in a little while. I myself hope for better and more transparent information at all times. Probably others want better security overall. Would it not be somewhat interesting if wayland were to be abandoned eventually due to having too few useful features compared to xserver?
 - froh1 hour ago
 except Wayland dropped the baby with the bathtub?for example standardized window management, left as an exercise to the GUI lib and the compositor? and woop woop X11 GUI apps need to be rewritten to support window management on WSL (Wayland based) and the network reconnect on hybernate also broke.But at least Games are faster, aren't they...
LtWorf6 hours ago
Or one could just use firejail, which comes with a number of pre made profiles for common applications.
- nosioptar5 hours ago
 The sandbox command works well on systems using SELinux.<a href="https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/selinux_users_and_administrators_guide/chap-security-enhanced_linux-securing_programs_using_sandbox" rel="nofollow">https://docs.redhat.com/en/documentation/red_hat_enterprise_...</a>
sunshine-o5 hours ago
This is a great article.I have little experience with lxc but I guess waypipe could be an option too.
calvinmorrison5 hours ago
Xlibre (the only current actively developed implementation of a X11 server) has a new extension - XNamespace to address some challenges as well.<a href="https://github.com/X11Libre/xserver/blob/master/doc/Xnamespace.md" rel="nofollow">https://github.com/X11Libre/xserver/blob/master/doc/Xnamespa...</a>
- Chu4eeno5 hours ago
 Not the only one, there's also a new one (written in zig) I've forgot the name of.edit: phoenix was the name: <a href="https://github.com/external-mirrors/phoenix#phoenix" rel="nofollow">https://github.com/external-mirrors/phoenix#phoenix</a>
 - mappu4 hours ago
 There's also this new one: <a href="https://github.com/joske/yserver" rel="nofollow">https://github.com/joske/yserver</a>
 - asveikau3 hours ago
 Hard for me to take that one seriously.. For example they call out byte swapping for endianness as the type of cruft holding back X11. Such a trivial thing to be concerned enough to put in the readme... (I guess Phoenix is also putting this..) Seems like mostly authored by Claude too.
 - shevy-java7 minutes ago
 > Seems like mostly authored by Claude too.This is a problem in many projects now. xserver and mruby for instance also succumbed to claude. It seems claude is the ultimate virus. It leaks into almost every project now. So I am not sure it can be used as differentiating criterium here merely for being claude AI slop. I've noticed a lot of documentation is now totally useless though; claude slop is just unreadable to me. It's like a person who is not able to think, wrote the documentation. I did not have this issue back when real humans wrote documentation, even though high quality documentation was always rare anyway. But, for instance, Jeremy Evans in his projects tends to write high-quality documentation in general, and I can understand it fine, whereas if you look at matz spinel, I have no idea what the AI slop in the README is really trying to convey. Or on ffmpeg, a german dev used AI slop to try to create some proposal, and someone else pointed out that this is pointless and impossible to read and understand, yet the original guy did not understand why real people don't want to be AI slop spammed. It's very strange.
- lotharcable1 hour ago
 XWayland is actively developed.XFree86, which is the "standalone DDX" you see on X11 desktops, is being actively maintained.