Public bug reported:
Binary package hint: udev
This wasn't a problem before 2.6.28, because force feedback for HID
devices was missing in ubuntu kernel. But now that will become a
problem.
d...@dmig-desktop:~$ ll /dev/input/
...
crw-rw---- 1 root root 13, 64 2002-01-22 04:57 event0
crw-rw---- 1 root root 13, 65 2002-01-22 04:57 event1
crw-rw---- 1 root root 13, 66 2002-01-22 04:57 event2
crw-rw---- 1 root root 13, 67 2002-01-22 04:57 event3
crw-rw---- 1 root root 13, 68 2002-01-22 04:57 event4
crw-rw---- 1 root root 13, 69 2002-01-22 04:57 event5
...
As you may see, all devices are owned by root. This will prevent anyone else
from using FF.
E.g. device event5 is a gamepad supporting force feedback, then id's node must
have group set to 'plugdev' (or some other).
Here is a message from linux-input maillist about this situation:
> I've read the documentation about force feedback in
> Documentation/input/ff.txt. But I'm rather unsure how to use it actually. So
> far I understood this you have to use /dev/input/eventX to access your ff-
> device. But normally only root has read and write access to this device files,
> while a joystick is used normally using /dev/input/jsX which can be used by a
> non-root user.
>
> So my actual question is: How can I use force feedback of a joystick without
> setting global read/write permissions to /dev/input/eventX?
The distribution should configure joystick eventX devices to either have
global read/write access, or read/write access for one group (which the
user is in), or have it chown the device to logged-in user, depending on
distribution conventions.
One can identify joystick devices from other eventX devices with udev
variable ENV{ID_CLASS}="joystick", or with existence of "/dev/input/by-
path/*-event-joystick", which is a symlink to the eventX device.
On Mandriva Linux, permissions are granted to logged-in user with
pam_console / ConsoleKit, with /dev/input/by-path/*-event-joystick.
** Affects: udev (Ubuntu)
Importance: Undecided
Status: New
--
wrong /dev/eventX permissions for force feedback devices
https://bugs.launchpad.net/bugs/344673
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