Is there a generic approach to automatically make some sysfs controls ch{own,mod} user-accessible?

Question

My current primary question motivator:

$ ls -l /sys/devices/platform/samsung
total 0
-rw-r--r-- 1 root root 4096 27. jaan  14:17 battery_life_extender
drwxr-xr-x 3 root root    0 19. jaan  18:40 leds
-r--r--r-- 1 root root 4096 26. jaan  23:37 modalias
-rw-r--r-- 1 root root 4096 27. jaan  12:57 performance_level
drwxr-xr-x 2 root root    0 24. jaan  00:35 power
drwxr-xr-x 4 root root    0 19. jaan  18:40 rfkill
lrwxrwxrwx 1 root root    0 27. jaan  13:03 subsystem -> ../../../bus/platform
-rw-r--r-- 1 root root 4096 27. jaan  13:03 uevent
-rw-r--r-- 1 root root 4096 26. jaan  23:37 usb_charge

I'd like to modify these without sudo. During a desktop session that. Privileged startup script is perfectly OK.

It's feeling like the solution is to have some sort of generic insmod parameters?

Bonsi Scott · Accepted Answer · 2013-01-27 13:22:16Z

up vote 1 down vote accepted

One solution would be a script, which changes permissions on that files using chmod and then setting you system so it would start the script on system bootup.

answered Jan 27 at 13:22

Bonsi Scott
8121211

	Indeed, simple startup script could do it. – lkraav Jan 27 at 14:34
	No sane kernel will honor S[UG]ID bits on scripts (for security reasons), in Perl there used to be a hack around this. – vonbrand Jan 27 at 22:49
	samsung-laptop.ko entries are solved with a simple `find /sys/devices/platform/samsung -type f -exec chown :wheel {} + -exec chmod g+w {} +` script in /etc/local.d. Unfortunately wifi rfkill state cannot be toggled like this, without elevated privileges, even though respective sysfs entries have been properly modded. I do have 95% of my laptop hotkeys working now as desired, so feels like a win nevertheless. – lkraav Jan 28 at 9:32
	As far as i know it is not the kernel who ignores the SUID-Bit, but rather its the shell. – Bonsi Scott Feb 8 at 17:37

vonbrand · Answer 2 · 2013-01-27 22:51:24Z

up vote 0 down vote

Can you use sysctl(8), perhaps through sudo(1)? Is it enough to preset them in sysctl.conf(7)?

answered Jan 27 at 22:51

vonbrand
5,5201628

man sysctl says "for /proc/sys" – lkraav Jan 28 at 9:29

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Is there a generic approach to automatically make some sysfs controls ch{own,mod} user-accessible?

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