ovpn: properly deconfigure UDP-tunnel

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>

diff --git a/drivers/net/ovpn/udp.c b/drivers/net/ovpn/udp.c
index aef8c0406ec918534b206c6ce6052b44e99d8316..f4d3bd070f1104fb199f7acc2f9770cfbc91037e 100644 (file)
--- 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);
+
+       WRITE_ONCE(udp_sk(sk)->encap_type, 0);
+       WRITE_ONCE(udp_sk(sk)->encap_rcv, NULL);
+       WRITE_ONCE(udp_sk(sk)->encap_destroy, NULL);
+
+       rcu_assign_sk_user_data(sk, NULL);
 }