net: ensure unbound stream socket to be chosen when not in a VRF

The commit a04a480d43 ("net: Require exact match for TCP socket
lookups if dif is l3mdev") only ensures that the correct socket is
selected for packets in a VRF. However, there is no guarantee that
the unbound socket will be selected for packets when not in a VRF.
By checking for a device match in compute_score() also for the case
when there is no bound device and attaching a score to this, the
unbound socket is selected. And if a failure is returned when there
is no device match, this ensures that bound sockets are never selected,
even if there is no unbound socket.

Signed-off-by: Mike Manning <mmanning@vyatta.att-mail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Tested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/inet6_hashtables.c

@@ -99,6 +99,7 @@ static inline int compute_score(struct sock *sk, struct net *net,
 				const int dif, const int sdif, bool exact_dif)
 {
 	int score = -1;
+	bool dev_match;
 
 	if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
 	    sk->sk_family == PF_INET6) {
@@ -109,15 +110,12 @@ static inline int compute_score(struct sock *sk, struct net *net,
 				return -1;
 			score++;
 		}
-		if (sk->sk_bound_dev_if || exact_dif) {
-			bool dev_match = (sk->sk_bound_dev_if == dif ||
-					  sk->sk_bound_dev_if == sdif);
+		dev_match = inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if,
+						 dif, sdif);
+		if (!dev_match)
+			return -1;
+		score++;
 
-			if (!dev_match)
-				return -1;
-			if (sk->sk_bound_dev_if)
-				score++;
-		}
 		if (sk->sk_incoming_cpu == raw_smp_processor_id())
 			score++;
 	}