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Olivier Fourdan 0f1c39de04 xwayland: Prevent Xserver grabs with rootless
Because of the design of most Wayland compositors, where the compositor
is both a Wayland server and an X11 window manager, any X11 client
issuing a server grab (i.e. XGrabServer()) can possibly hang the whole
desktop when Xwayland is running rootless.

This can happen with e.g. ImageMagick's import command with mutter.

1. "import" is launched and issues an XServerGrab(),
2. Xwayland restricts access to that "import" X11 client alone,
3. mutter continues to process events until it needs to sync with
   Xwayland (there's variability in time before the hang occurs),
4. When mutter does an XSync() (explicitly or implicitly through some
   other Xlib call), it will stop waiting for Xwayland to reply,
5. Xwayland waits for the XServerGrab() to be released by import,
6. "import" waits for a user input to release the XServerGrab(),
7. mutter is stuck waiting on Xwayland and does not process input
   events...

To prevent this, re-route the GrabServer/UngrabServer requests and
pretend the grab works but actually does nothing at all for all clients
but the X11 window manager (which can still issue X11 server grabs, at
its own risks).

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Closes: https://bugzilla.redhat.com/1914021
(cherry picked from commit a77d95af61)
2022-09-14 09:56:31 +02:00
.gitlab-ci ci: remove redundant slash in libxcvt repository url 2022-09-14 09:56:31 +02:00
composite Drop Xorg DDX 2022-01-18 12:09:52 +01:00
damageext Remove autotools support 2021-10-27 13:15:40 +03:00
dbe Drop Xorg DDX 2022-01-18 12:09:52 +01:00
dix dix: Skip more code in SetRootClip for ROOT_CLIP_INPUT_ONLY 2022-09-14 09:56:31 +02:00
doc Remove autotools support 2021-10-27 13:15:40 +03:00
dri3 Drop Xorg DDX 2022-01-18 12:09:52 +01:00
fb Drop Xorg DDX 2022-01-18 12:09:52 +01:00
glamor Drop Xorg DDX 2022-01-18 12:09:52 +01:00
glx Drop Xorg DDX 2022-01-18 12:09:52 +01:00
hw xwayland: Prevent Xserver grabs with rootless 2022-09-14 09:56:31 +02:00
include Drop config directory 2022-01-18 12:09:52 +01:00
m4 Add ax_pthread.m4 to m4/ 2016-05-29 19:20:51 -07:00
man Remove autotools support 2021-10-27 13:15:40 +03:00
mi Drop Xorg DDX 2022-01-18 12:09:52 +01:00
miext Drop miext/shadow directory 2022-01-18 12:09:52 +01:00
os os: print registers in the libunwind version of xorg_backtrace() 2022-07-01 10:02:16 +02:00
present Drop Xorg DDX 2022-01-18 12:09:52 +01:00
randr randr: Add "RANDR Emulation" property 2022-05-25 09:43:17 +02:00
record record: Fix out of bounds access in SwapCreateRegister() 2021-12-14 15:00:00 +02:00
render render: Fix build with gcc 12 2022-01-28 10:32:04 +01:00
test Drop Xephyr / kdrive DDX 2022-01-18 12:09:52 +01:00
Xext Drop Xorg DDX 2022-01-18 12:09:52 +01:00
xfixes xfixes: Fix out of bounds access in *ProcXFixesCreatePointerBarrier() 2021-12-14 15:00:01 +02:00
Xi Convert more funcs to use InternalEvent. 2021-12-19 20:01:04 +00:00
xkb xkb: Avoid length-check failure on empty strings. 2022-09-14 09:56:31 +02:00
.appveyor.yml Drop Xephyr / kdrive DDX 2022-01-18 12:09:52 +01:00
.dir-locals.el .dir-locals.el: Add missing final newline 2019-10-01 17:05:28 +00:00
.gitignore .gitignore: Add new autotools file 'test-driver' 2014-04-21 13:41:42 -07:00
.gitlab-ci.yml Don't install Xvfb 2022-01-18 12:09:52 +01:00
COPYING modesetting: Merge modesetting's COPYING into the xserver's. 2014-09-15 12:46:02 -07:00
meson.build Bump version to 22.1.3 2022-07-12 15:48:31 +02:00
meson_options.txt meson: Build Xwayland unconditionally 2022-01-18 12:09:52 +01:00
README.md Fix spelling/wording issues 2020-07-05 13:07:33 -07:00
xserver.ent.in doc: relocate xserver.ent in the package root directory 2011-05-14 11:22:26 -07:00

X Server

The X server accepts requests from client applications to create windows, which are (normally rectangular) "virtual screens" that the client program can draw into.

Windows are then composed on the actual screen by the X server (or by a separate composite manager) as directed by the window manager, which usually communicates with the user via graphical controls such as buttons and draggable titlebars and borders.

For a comprehensive overview of X Server and X Window System, consult the following article: https://en.wikipedia.org/wiki/X_server

All questions regarding this software should be directed at the Xorg mailing list:

https://lists.freedesktop.org/mailman/listinfo/xorg

The primary development code repository can be found at:

https://gitlab.freedesktop.org/xorg/xserver

For patch submission instructions, see:

https://www.x.org/wiki/Development/Documentation/SubmittingPatches

As with other projects hosted on freedesktop.org, X.Org follows its Code of Conduct, based on the Contributor Covenant. Please conduct yourself in a respectful and civilized manner when using the above mailing lists, bug trackers, etc:

https://www.freedesktop.org/wiki/CodeOfConduct