ファイルを読み取る権限がある理由はどうすればわかりますか？ [閉鎖]

CentOS SSHアカウントで確認したばかりのものは次のとおりです。

$ stat /dev/kvm   
  File: `/dev/kvm'
  Size: 0               Blocks: 0          IO Block: 4096   character special file
Device: 5h/5d   Inode: 39768216    Links: 1     Device type: a,e8
Access: (0666/crw-rw-rw-)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2014-07-12 13:50:33.015216048 +0200
Modify: 2014-07-12 13:50:33.015216048 +0200
Change: 2014-07-12 13:50:33.015216048 +0200

$ id
uid=502(jacek) gid=502(jacek) groups=502(jacek)

$ strace -e open cat /dev/kvm
open("/etc/ld.so.cache", O_RDONLY)      = 3
open("/lib64/libc.so.6", O_RDONLY)      = 3
open("/usr/lib/locale/locale-archive", O_RDONLY) = 3
open("/dev/kvm", O_RDONLY)              = 3
cat: /dev/kvmopen("/usr/share/locale/locale.alias", O_RDONLY) = 4
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
: Invalid argument

$ getfacl /dev/kvm
getfacl: Removing leading '/' from absolute path names
# file: dev/kvm
# owner: root
# group: root
user::rw-
group::rw-
other::rw-

ここでなぜopen成功したのですか？ ACLに加えて、ユーザーがファイルを開くことができるかどうかを判断するために使用できるメカニズムはありますか？クエリにはどのコマンドを使用できますか？