MariaDB CONNECT engine to read external file

I would like to read an external file into MariaDB using the CONNECT engine. However, when trying to read from the file, I get an error message:

MariaDB [test]> create table test ( name varchar(100), team varchar(100) ) engine=CONNECT table_type=CSV file_name='/tmp/data.csv' header=1 sep_char=',' quoted=0;
Query OK, 0 rows affected (0.24 sec)

MariaDB [test]> select * from test;
ERROR 1296 (HY000): Got error 174 'Open() error 13 on /tmp/data.csv: Permission denied' from CONNECT

Checking the filesystem permissions gives me:

divingt@grisu ~ $ ls -l /tmp/data.csv
-rw-rw-rw- 1 divingt divingt 1658 Dec 31 13:59 /tmp/data.csv

So everybody should be able to read and write from the file.

Also in MYSQL the permissions allow for everything:

MariaDB [test]> SHOW GRANTS;
+------------------------------------------------------------------------------------------------+
| Grants for root@localhost                                                                      |
+------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED VIA unix_socket WITH GRANT OPTION |
| GRANT PROXY ON ''@'%' TO 'root'@'localhost' WITH GRANT OPTION                                  |
+------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)

I run a Linux Mint system.

Thanks a lot for any help.

Solution

It turns out that the reason was that apparmor prevented mysqld from reading from reading the file. Disabling it (or changing the permissions) solved the problem.