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@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: Vadim Fedorenko <vfedorenko@novek.ru>
cc: David S. Miller <davem@davemloft.net>
cc: linux-afs@lists.infradead.org
---

 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);

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Fri, 29 Apr 2022 21:05:16 +0100 you 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.
> 
> [...]

Here is the summary with links:
  - [net] rxrpc: Enable IPv6 checksums on transport socket
    https://git.kernel.org/netdev/net/c/39cb9faa5d46

You are awesome, thank you!
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