Re: [PATCH] rxrpc: Enable IPv6 checksums on transport socket

[Marc Dionne]

On Wed, Apr 27, 2022 at 6:30 PM David Howells <dhowells@xxxxxxxxxx> wrote:
>
> AF_RXRPC doesn't currently enable IPv6 UDP Tx checksums on the transport
> socket it opens and the checksums in the packets it generates end up 0.
>
> It probably should also enable IPv6 UDP Rx checksums and IPv4 UDP
> checksums.  The latter only seem to be applied if the socket family is
> AF_INET and don't seem to apply if it's AF_INET6.  IPv4 packets from an
> IPv6 socket seem to have checksums anyway.
>
> What seems to have happened is that the inet_inv_convert_csum() call didn't
> get converted to the appropriate udp_port_cfg parameters - and
> udp_sock_create() disables checksums unless explicitly told not too.
>
> Fix this by enabling the three udp_port_cfg checksum options.
>
> Fixes: 1a9b86c9fd95 ("rxrpc: use udp tunnel APIs instead of open code in rxrpc_open_socket")
> Reported-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Xin Long <lucien.xin@xxxxxxxxx>
> cc: Vadim Fedorenko <vfedorenko@xxxxxxxx>
> cc: David S. Miller <davem@xxxxxxxxxxxxx>
> cc: linux-afs@xxxxxxxxxxxxxxxxxxx
> ---
>
>  net/rxrpc/local_object.c |    3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
> index a4111408ffd0..6a1611b0e303 100644
> --- a/net/rxrpc/local_object.c
> +++ b/net/rxrpc/local_object.c
> @@ -117,6 +117,7 @@ static int rxrpc_open_socket(struct rxrpc_local *local, struct net *net)
>                local, srx->transport_type, srx->transport.family);
>
>         udp_conf.family = srx->transport.family;
> +       udp_conf.use_udp_checksums = true;
>         if (udp_conf.family == AF_INET) {
>                 udp_conf.local_ip = srx->transport.sin.sin_addr;
>                 udp_conf.local_udp_port = srx->transport.sin.sin_port;
> @@ -124,6 +125,8 @@ static int rxrpc_open_socket(struct rxrpc_local *local, struct net *net)
>         } else {
>                 udp_conf.local_ip6 = srx->transport.sin6.sin6_addr;
>                 udp_conf.local_udp_port = srx->transport.sin6.sin6_port;
> +               udp_conf.use_udp6_tx_checksums = true;
> +               udp_conf.use_udp6_rx_checksums = true;
>  #endif
>         }
>         ret = udp_sock_create(net, &udp_conf, &local->socket);

Works for me, and I think we want all 3 settings, as a socket created
by a userspace application other than kafs may be a V4 socket.

Reviewed-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>

Marc