The SO_BINDTODEVICE and SO_BINDTOIFINDEX sockopts return -ENOPROTOOPT
if CONFIG_NETDEVICES is disabled, even if the lo interface exists. I
believe it would be prudent to allow for valid bindings even if
CONFIG_NETDEVICES were disabled, as an error here would be inconsistent.

Signed-off-by: Ethan Ferguson <ethanf108@gmail.com>

---
 net/core/sock.c | 56 +++++++++++++------------------------------------
 1 file changed, 15 insertions(+), 41 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index e8551df8330f..d2da59700ecf 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -634,18 +634,14 @@ EXPORT_SYMBOL(sk_dst_check);
 
 static int sock_bindtoindex_locked(struct sock *sk, int ifindex)
 {
-	int ret = -ENOPROTOOPT;
-#ifdef CONFIG_NETDEVICES
 	struct net *net = sock_net(sk);
 
 	/* Sorry... */
-	ret = -EPERM;
 	if (sk->sk_bound_dev_if && !ns_capable(net->user_ns, CAP_NET_RAW))
-		goto out;
+		return -EPERM;
 
-	ret = -EINVAL;
 	if (ifindex < 0)
-		goto out;
+		return -EINVAL;
 
 	/* Paired with all READ_ONCE() done locklessly. */
 	WRITE_ONCE(sk->sk_bound_dev_if, ifindex);
@@ -654,12 +650,7 @@ static int sock_bindtoindex_locked(struct sock *sk, int ifindex)
 		sk->sk_prot->rehash(sk);
 	sk_dst_reset(sk);
 
-	ret = 0;
-
-out:
-#endif
-
-	return ret;
+	return 0;
 }
 
 int sock_bindtoindex(struct sock *sk, int ifindex, bool lock_sk)
@@ -678,15 +669,12 @@ EXPORT_SYMBOL(sock_bindtoindex);
 
 static int sock_setbindtodevice(struct sock *sk, sockptr_t optval, int optlen)
 {
-	int ret = -ENOPROTOOPT;
-#ifdef CONFIG_NETDEVICES
+	int ret, index;
 	struct net *net = sock_net(sk);
 	char devname[IFNAMSIZ];
-	int index;
 
-	ret = -EINVAL;
 	if (optlen < 0)
-		goto out;
+		return -EINVAL;
 
 	/* Bind this socket to a particular device like "eth0",
 	 * as specified in the passed interface name. If the
@@ -697,9 +685,8 @@ static int sock_setbindtodevice(struct sock *sk, sockptr_t optval, int optlen)
 		optlen = IFNAMSIZ - 1;
 	memset(devname, 0, sizeof(devname));
 
-	ret = -EFAULT;
 	if (copy_from_sockptr(devname, optval, optlen))
-		goto out;
+		return -EFAULT;
 
 	index = 0;
 	if (devname[0] != '\0') {
@@ -710,16 +697,13 @@ static int sock_setbindtodevice(struct sock *sk, sockptr_t optval, int optlen)
 		if (dev)
 			index = dev->ifindex;
 		rcu_read_unlock();
-		ret = -ENODEV;
 		if (!dev)
-			goto out;
+			return -ENODEV;
 	}
 
 	sockopt_lock_sock(sk);
 	ret = sock_bindtoindex_locked(sk, index);
 	sockopt_release_sock(sk);
-out:
-#endif
 
 	return ret;
 }
@@ -727,42 +711,32 @@ static int sock_setbindtodevice(struct sock *sk, sockptr_t optval, int optlen)
 static int sock_getbindtodevice(struct sock *sk, sockptr_t optval,
 				sockptr_t optlen, int len)
 {
-	int ret = -ENOPROTOOPT;
-#ifdef CONFIG_NETDEVICES
-	int bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
+	int ret, bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
 	struct net *net = sock_net(sk);
 	char devname[IFNAMSIZ];
 
 	if (bound_dev_if == 0) {
 		len = 0;
-		goto zero;
+		goto copy_len;
 	}
 
-	ret = -EINVAL;
 	if (len < IFNAMSIZ)
-		goto out;
+		return -EINVAL;
 
 	ret = netdev_get_name(net, devname, bound_dev_if);
 	if (ret)
-		goto out;
+		return ret;
 
 	len = strlen(devname) + 1;
 
-	ret = -EFAULT;
 	if (copy_to_sockptr(optval, devname, len))
-		goto out;
+		return -EFAULT;
 
-zero:
-	ret = -EFAULT;
+copy_len:
 	if (copy_to_sockptr(optlen, &len, sizeof(int)))
-		goto out;
-
-	ret = 0;
-
-out:
-#endif
+		return -EFAULT;
 
-	return ret;
+	return 0;
 }
 
 bool sk_mc_loop(const struct sock *sk)
-- 
2.56.0