I would like to control permissions to use sound card. There are devices "/dev/snd/*", the owner is "root", group is "audio", permissions "660". So, I would expect only users in "audio" group could use sound card, however it doesn't work. I have a user "u1" which is not in group "audio", however he has access! I've found out that the access is controlled with ACL, so
getfacl shows the following:
# file: timer # owner: root # group: audio # flags: --t user::rw- user:u1:rw- group::rw- mask::rw- other::---
The line "user:u1:rw-" magically appears again even if I remove it with
For me it looks like that there is a root-owned process which automatically adds permissions to any user ignoring "audio" group membership.
Why is the access granted? How to revoke access to sound card for a user?