net/tls: Fail tls_sw_splice_read() after a failed async decrypt

When an async decrypt fails, tls_decrypt_done() records the error in
ctx->async_wait.err and calls tls_err_abort(), which stores it in
sk_err. tls_sw_recvmsg() and tls_sw_read_sock() each read
async_wait.err once they hold the reader lock and fail the call: a
record that did not authenticate breaks the connection.

tls_sw_splice_read() has no such check, and sk_err does not stand in
for one. tls_rx_rec_wait() tests sk_err only inside the loop it
skips whenever a record is already parsed, and the first reader to
reach sock_error() clears it, while async_wait.err persists. A
splice therefore keeps delivering records on a connection that
recvmsg() and read_sock() refuse to read.

Read async_wait.err in tls_sw_splice_read() as the other two readers
do.

Fixes: f314bfee81 ("tls: rx: return the already-copied data on crypto error")
Reviewed-by: Jakub Kicinski <[email protected]>
Signed-off-by: Chuck Lever <[email protected]>
Reviewed-by: Sabrina Dubroca <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

net/tls/tls_sw.c

@@ -2014,6 +2014,11 @@ ssize_t tls_sw_splice_read(struct socket *sock,  loff_t *ppos,
 	if (err < 0)
 		return err;
 
+	/* If crypto failed the connection is broken */
+	err = ctx->async_wait.err;
+	if (err)
+		goto splice_read_end;
+
 	if (!skb_queue_empty(&ctx->rx_list)) {
 		skb = __skb_dequeue(&ctx->rx_list);
 	} else {