Re: [PATCH net 1/5] ovpn: properly deconfigure UDP-tunnel

[Michal Swiatkowski <michal.swiatkowski@linux.intel.com>]

On Fri, May 30, 2025 at 12:12:50PM +0200, Antonio Quartulli wrote:
> When deconfiguring a UDP-tunnel from a socket, we cannot
> call setup_udp_tunnel_sock() with an empty config, because
> this helper is expected to be invoked only during setup.
> 
> Get rid of the call to setup_udp_tunnel_sock() and just
> revert what it did during socket initialization..
> 
> Note that the global udp_encap_needed_key and the GRO state
> are left untouched: udp_destroy_socket() will eventually
> take care of them.
> 
> Cc: Sabrina Dubroca <sd@queasysnail.net>
> Cc: Oleksandr Natalenko <oleksandr@natalenko.name>
> Fixes: ab66abbc769b ("ovpn: implement basic RX path (UDP)")
> Reported-by: Paolo Abeni <pabeni@redhat.com>
> Closes: https://lore.kernel.org/netdev/1a47ce02-fd42-4761-8697-f3f315011cc6@redhat.com
> Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
> ---
>  drivers/net/ovpn/udp.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ovpn/udp.c b/drivers/net/ovpn/udp.c
> index aef8c0406ec9..89bb50f94ddb 100644
> --- a/drivers/net/ovpn/udp.c
> +++ b/drivers/net/ovpn/udp.c
> @@ -442,8 +442,16 @@ int ovpn_udp_socket_attach(struct ovpn_socket *ovpn_sock,
>   */
>  void ovpn_udp_socket_detach(struct ovpn_socket *ovpn_sock)
>  {
> -	struct udp_tunnel_sock_cfg cfg = { };
> +	struct sock *sk = ovpn_sock->sock->sk;
>  
> -	setup_udp_tunnel_sock(sock_net(ovpn_sock->sock->sk), ovpn_sock->sock,
> -			      &cfg);
> +	/* Re-enable multicast loopback */
> +	inet_set_bit(MC_LOOP, sk);
> +	/* Disable CHECKSUM_UNNECESSARY to CHECKSUM_COMPLETE conversion */
> +	inet_dec_convert_csum(sk);
> +
> +	udp_sk(sk)->encap_type = 0;
> +	udp_sk(sk)->encap_rcv = NULL;
> +	udp_sk(sk)->encap_destroy = NULL;
> +
> +	rcu_assign_sk_user_data(sk, NULL);
>  }
> -- 
> 2.49.0

LGTM, thanks
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>