And take a look at those permissions on your machine and see what they show for you:

crw-rw-rw- 1 root root 1, 8 Jul 15 11:27 /dev/random

crw-rw-rw- 1 root root 1, 9 Jul 15 11:27 /dev/urandom

So, if the default permission is read/write by any user, what limitation should this new syscall add?