Android 5.0 SEAndroid下如何获得对一个内核节点的访问权限

/dev/tegra.* u:object_r:video_device:s0
/dev/tf_driver u:object_r:tee_device:s0
/dev/tty u:object_r:owntty_device:s0
/dev/tty[0-9]* u:object_r:tty_device:s0
# We add here
/dev/wf_bt              u:object_r:wf_bt_device:s0

# Device types
type device, dev_type, fs_type;
type alarm_device, dev_type, mlstrustedobject;
type adb_device, dev_type;
type ashmem_device, dev_type, mlstrustedobject;
type audio_device, dev_type;
type binder_device, dev_type, mlstrustedobject;
type block_device, dev_type;
# We add here
type wf_bt_device, dev_type;

# Read/Write to /proc/net/xt_qtaguid/ctrl and and /dev/xt_qtaguid.
allow system_server qtaguid_proc:file rw_file_perms;
allow system_server qtaguid_device:chr_file rw_file_perms;

# chr_file表示字符设备文件，如果是普通文件用file，目录请用dir
# rw_file_perms代表读写权限
allow system_server wf_bt_device:chr_file rw_file_perms;