rtnetlink: do not use RTM_GETLINK directly

Userspace sends RTM_GETLINK type, but the kernel substracts
RTM_BASE from this, i.e. 'type' doesn't contain RTM_GETLINK
anymore but instead RTM_GETLINK - RTM_BASE.

This caused the calcit callback to not be invoked when it
should have been (and vice versa).

While at it, also fix a off-by one when checking family index. vs
handler array size.

Fixes: e1fa6d21 ("rtnetlink: call rtnl_calcit directly")
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -4167,7 +4167,7 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (kind != 2 && !netlink_net_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
-	if (family > ARRAY_SIZE(rtnl_msg_handlers))
+	if (family >= ARRAY_SIZE(rtnl_msg_handlers))
 		family = PF_UNSPEC;
 
 	rcu_read_lock();
@@ -4196,7 +4196,7 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 		refcount_inc(&rtnl_msg_handlers_ref[family]);
 
-		if (type == RTM_GETLINK)
+		if (type == RTM_GETLINK - RTM_BASE)
 			min_dump_alloc = rtnl_calcit(skb, nlh);
 
 		rcu_read_unlock();