[Ubuntu] the permissions of lampp mysql and phpmyadmin

After I run this command in Ubuntu:

sudo chmod 777 -R /opt/lampp

Then I start the lampp

sudo /opt/lampp/lampp start

I got the warnning:

Starting XAMPP for Linux 1.7.3a...
XAMPP: Starting Apache with SSL (and PHP5)...
XAMPP: Starting MySQL...
Warning: World-writable config file '/opt/lampp/etc/my.cnf' is ignored
Warning: World-writable config file '/opt/lampp/etc/my.cnf' is ignored
XAMPP: Starting ProFTPD...
XAMPP for Linux started.

Then I visite the phpmyadmin in the browser with : http://127.0.0.1/phpmyadmin, I also got the error:

Wrong permissions on configuration file, should not be world writable!

The resolved:

sudo chmod 755 -R /opt/lampp

That is to say, We can set the 777 permissions to the /opt/lampp because the security reason then mysql can't start.