How to grant a RuntimePermission to a shared object?

I have a shared object in a temporary directory, /tmp/libmylib.so, that I'm calling from Java. If I give a blanket security permission like the below, everything works fine:

grant {
  permission java.lang.RuntimePermission "loadLibrary.*";
}

But if I give a specific permission like the below, an exception will be thrown.

grant {
  permission java.lang.RuntimePermission "loadLibrary.mylib";
}

java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "loadLibrary./tmp/mylib.so")

I tried to give a read/write permission to /tmp/- but didn't work.

Any ideas?