[PATCH net 2/3] rxrpc: Fix re-decryption of RESPONSE packets

[David Howells <dhowells@redhat.com>]

If a RESPONSE packet gets a temporary failure during processing, it may end
up in a partially decrypted state - and then get requeued for a retry.

Fix this by just discarding the packet; we will send another CHALLENGE
packet and thereby elicit a further response.  Similarly, discard an
incoming CHALLENGE packet if we get an error whilst generating a RESPONSE;
the server will send another CHALLENGE.

Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Closes: https://sashiko.dev/#/patchset/20260422161438.2593376-4-dhowells@redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: Eric Dumazet <edumazet@google.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org
cc: stable@kernel.org
---
 include/trace/events/rxrpc.h |  1 -
 net/rxrpc/conn_event.c       | 14 ++------------
 2 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index 13b9d017f8e1..573f2df3a2c9 100644
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -285,7 +285,6 @@
 	EM(rxrpc_conn_put_unidle,		"PUT unidle  ") \
 	EM(rxrpc_conn_put_work,			"PUT work    ") \
 	EM(rxrpc_conn_queue_challenge,		"QUE chall   ") \
-	EM(rxrpc_conn_queue_retry_work,		"QUE retry-wk") \
 	EM(rxrpc_conn_queue_rx_work,		"QUE rx-work ") \
 	EM(rxrpc_conn_see_new_service_conn,	"SEE new-svc ") \
 	EM(rxrpc_conn_see_reap_service,		"SEE reap-svc") \
diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c
index aee977291d90..a2130d25aaa9 100644
--- a/net/rxrpc/conn_event.c
+++ b/net/rxrpc/conn_event.c
@@ -389,7 +389,6 @@ void rxrpc_process_delayed_final_acks(struct rxrpc_connection *conn, bool force)
 static void rxrpc_do_process_connection(struct rxrpc_connection *conn)
 {
 	struct sk_buff *skb;
-	int ret;
 
 	if (test_and_clear_bit(RXRPC_CONN_EV_CHALLENGE, &conn->events))
 		rxrpc_secure_connection(conn);
@@ -398,17 +397,8 @@ static void rxrpc_do_process_connection(struct rxrpc_connection *conn)
 	 * connection that each one has when we've finished with it */
 	while ((skb = skb_dequeue(&conn->rx_queue))) {
 		rxrpc_see_skb(skb, rxrpc_skb_see_conn_work);
-		ret = rxrpc_process_event(conn, skb);
-		switch (ret) {
-		case -ENOMEM:
-		case -EAGAIN:
-			skb_queue_head(&conn->rx_queue, skb);
-			rxrpc_queue_conn(conn, rxrpc_conn_queue_retry_work);
-			break;
-		default:
-			rxrpc_free_skb(skb, rxrpc_skb_put_conn_work);
-			break;
-		}
+		rxrpc_process_event(conn, skb);
+		rxrpc_free_skb(skb, rxrpc_skb_put_conn_work);
 	}
 }