adhd: Restrict client from creating sidetone streams

Restrict client from creating sidetone streams. Sidetone streams should
only be created by sending a D-Bus message to the server. Now it's
causing the rclient_message fuzz to fail because the client only creates
a single input/output stream, where for sidetone, it expects to have a
pair of input and output stream.

BUG=b:346963849
BUG=b:328145742
TEST=run fuzzer test case
TEST=tast run ${DUT} audio.CrasSidetone

Change-Id: I70fee530907ea2d0e54e1adee8c1ad946393c315
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/5632936
Commit-Queue: Norman Bintang <[email protected]>
Tested-by: [email protected] <[email protected]>
Tested-by: Norman Bintang <[email protected]>
Reviewed-by: Li-Yu Yu <[email protected]>

Author: Norman Bintang

cras/src/server/cras_rclient_util.c

@@ -177,6 +177,11 @@ int rclient_handle_client_stream_connect(struct cras_rclient* client,
   if (client->client_type != CRAS_CLIENT_TYPE_UNKNOWN) {
     stream_config.client_type = client->client_type;
   }
+  if ((stream_config.flags & SIDETONE_STREAM) == SIDETONE_STREAM) {
+    syslog(LOG_ERR, "Creating a sidetone stream from a client is not allowed");
+    rc = -EINVAL;
+    goto cleanup_config;
+  }
   rc = stream_list_add(cras_iodev_list_get_stream_list(), &stream_config,
                        &stream);
   if (rc) {