Re: [PATCH] net: remove CONFIG_NETDEVICES requirement for SO_BINDTODEVICE and SO_BINDTOIFINDEX

[Kuniyuki Iwashima <kuniyu@google.com>]

On Tue, 10 Nov 2026 15:45:24 -0500, Ethan Ferguson wrote:
> 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;

nit: keep the reverse xmas tree order.

Also, please specify the target tree in the Subject.

  [PATCH net-next v2] ....

See Documentation/process/maintainer-netdev.rst

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