Multicast netlink for non-root process

[Jean Tourrilhes]

	Hi,

	I'm developping an application that need to monitor every
network interface of the system. Network interfaces are
virtual/dynamic and go up and down all the time, so to keep track of
my interface list, I'm listening for RTM_NEWLINK events on the
RTnetLink socket (RTMGRP_LINK multicast group).

	Problem : this works only as ROOT.
	And my mother told me that having my application running as
root is bad for my health.

	The cause is here :
----------- net/netlink/af_netlink.c - l322 ------------------

static int netlink_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
{
[...]
	/* Only superuser is allowed to listen multicasts */
	if (nladdr->nl_groups && !capable(CAP_NET_ADMIN))
		return -EPERM;
--------------------------------------------------------------

	Why ?
	Why ?
	Why ?

	Have a good day...

	Jean