l2tp: rework socket comparison in __l2tp_ip*_bind_lookup()

Split conditions, so that each test becomes clearer.

Also, for l2tp_ip, check if "laddr" is 0. This prevents a socket from
binding to the unspecified address when other sockets are already bound
using the same device (if any), connection ID and namespace.

Same thing for l2tp_ip6: add ipv6_addr_any(laddr) and
ipv6_addr_any(raddr) tests to ensure that an IPv6 unspecified address
passed as parameter is properly treated a wildcard.
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_ip.c

@@ -56,13 +56,23 @@ static struct sock *__l2tp_ip_bind_lookup(const struct net *net, __be32 laddr,
 		const struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
 		const struct inet_sock *inet = inet_sk(sk);
 
-		if ((l2tp->conn_id == tunnel_id) &&
-		    net_eq(sock_net(sk), net) &&
-		    !(inet->inet_rcv_saddr && inet->inet_rcv_saddr != laddr) &&
-		    (!inet->inet_daddr || !raddr || inet->inet_daddr == raddr) &&
-		    (!sk->sk_bound_dev_if || !dif ||
-		     sk->sk_bound_dev_if == dif))
-			goto found;
+		if (!net_eq(sock_net(sk), net))
+			continue;
+
+		if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
+			continue;
+
+		if (inet->inet_rcv_saddr && laddr &&
+		    inet->inet_rcv_saddr != laddr)
+			continue;
+
+		if (inet->inet_daddr && raddr && inet->inet_daddr != raddr)
+			continue;
+
+		if (l2tp->conn_id != tunnel_id)
+			continue;
+
+		goto found;
 	}
 
 	sk = NULL;

net/l2tp/l2tp_ip6.c

@@ -69,13 +69,24 @@ static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
 		const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
 		const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
 
-		if ((l2tp->conn_id == tunnel_id) &&
-		    net_eq(sock_net(sk), net) &&
-		    (!sk_laddr || ipv6_addr_any(sk_laddr) || ipv6_addr_equal(sk_laddr, laddr)) &&
-		    (!raddr || ipv6_addr_any(sk_raddr) || ipv6_addr_equal(sk_raddr, raddr)) &&
-		    (!sk->sk_bound_dev_if || !dif ||
-		     sk->sk_bound_dev_if == dif))
-			goto found;
+		if (!net_eq(sock_net(sk), net))
+			continue;
+
+		if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
+			continue;
+
+		if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
+		    !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
+			continue;
+
+		if (!ipv6_addr_any(sk_raddr) && raddr &&
+		    !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
+			continue;
+
+		if (l2tp->conn_id != tunnel_id)
+			continue;
+
+		goto found;
 	}
 
 	sk = NULL;