Arch Linux

Description:
The /lib/udev/rules.d/90-backlight.rules which is provided by the package has an error in it which prevents the user from adjusting his keyboard brightness without root privileges even if he added his user to the video group.

Additional info:
Affects acpilight 1.1-2 without any additional configuration

Flawed config /lib/udev/rules.d/90-backlight.rules :

# Allow video group to control backlight and leds
SUBSYSTEM=="backlight", ACTION=="add", \
RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness", \
RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"
SUBSYSTEM=="leds", ACTION=="add", KERNEL=="*::kbd_backlight", \
RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness", \
RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"

Should be:

# Allow video group to control backlight and leds
SUBSYSTEM=="backlight", ACTION=="add", \
RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness", \
RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"
SUBSYSTEM=="leds", ACTION=="add", KERNEL=="*::kbd_backlight", \
RUN+="/bin/chgrp video /sys/class/leds/%k/brightness", \
RUN+="/bin/chmod g+w /sys/class/leds/%k/brightness"



Steps to reproduce:
-Install acpilight through pacman
-Add your user to the video group
-Reboot
-identify your keyboard backlight with xbacklight -l.
-Try to run the following command without sudo or root priviledges:
xbacklight -ctrl XXXXXXX 100
(where XXXX is the identifier for your keyboard backlight)