@@ -17,6 +17,17 @@ static unsigned char rdesc[] = {
 	0xa1, 0x01,		/* COLLECTION (Application) */
 	0x09, 0x01,			/* Usage (Vendor Usage 0x01) */
 	0xa1, 0x00,			/* COLLECTION (Physical) */
+	0x85, 0x02,				/* REPORT_ID (2) */
+	0x19, 0x01,				/* USAGE_MINIMUM (1) */
+	0x29, 0x08,				/* USAGE_MAXIMUM (3) */
+	0x15, 0x00,				/* LOGICAL_MINIMUM (0) */
+	0x25, 0xff,				/* LOGICAL_MAXIMUM (255) */
+	0x95, 0x08,				/* REPORT_COUNT (8) */
+	0x75, 0x08,				/* REPORT_SIZE (8) */
+	0x81, 0x02,				/* INPUT (Data,Var,Abs) */
+	0xc0,				/* END_COLLECTION */
+	0x09, 0x01,			/* Usage (Vendor Usage 0x01) */
+	0xa1, 0x00,			/* COLLECTION (Physical) */
 	0x85, 0x01,				/* REPORT_ID (1) */
 	0x06, 0x00, 0xff,			/* Usage Page (Vendor Defined Page 1) */
 	0x19, 0x01,				/* USAGE_MINIMUM (1) */

@@ -635,6 +646,53 @@ static int test_attach_detach(int uhid_fd, int dev_id)
 	return ret;
 }
 
+/*
+ * Attach hid_change_report_id to the given uhid device,
+ * retrieve and open the matching hidraw node,
+ * inject one event in the uhid device,
+ * check that the program sees it and can change the data
+ */
+static int test_hid_change_report(int uhid_fd, int dev_id)
+{
+	struct test_params params;
+	int err, hidraw_fd = -1;
+	u8 buf[10] = {0};
+	int ret = -1;
+
+	err = prep_test(dev_id, "hid_change_report_id", &params);
+	if (!ASSERT_EQ(err, 0, "prep_test(hid_change_report_id)"))
+		goto cleanup;
+
+	hidraw_fd = params.hidraw_fd;
+
+	/* inject one event */
+	buf[0] = 1;
+	buf[1] = 42;
+	send_event(uhid_fd, buf, 6);
+
+	/* read the data from hidraw */
+	memset(buf, 0, sizeof(buf));
+	err = read(hidraw_fd, buf, sizeof(buf));
+	if (!ASSERT_EQ(err, 9, "read_hidraw"))
+		goto cleanup;
+
+	if (!ASSERT_EQ(buf[0], 2, "hid_change_report_id"))
+		goto cleanup;
+
+	if (!ASSERT_EQ(buf[1], 42, "hid_change_report_id"))
+		goto cleanup;
+
+	if (!ASSERT_EQ(buf[2], 0, "leftovers_from_previous_test"))
+		goto cleanup;
+
+	ret = 0;
+
+cleanup:
+	cleanup_test(&params);
+
+	return ret;
+}
+
 void serial_test_hid_bpf(void)
 {
 	int err, uhid_fd;

@@ -660,6 +718,8 @@ void serial_test_hid_bpf(void)
 	ASSERT_OK(err, "hid");
 	err = test_attach_detach(uhid_fd, dev_id);
 	ASSERT_OK(err, "hid_attach_detach");
+	err = test_hid_change_report(uhid_fd, dev_id);
+	ASSERT_OK(err, "hid_change_report");
 
 	destroy(uhid_fd);
 

@@ -32,7 +32,20 @@ int BPF_PROG(hid_first_event, struct hid_bpf_ctx *hid_ctx)
 
 	rw_data[2] = rw_data[1] + 5;
 
-	return 0;
+	return hid_ctx->size;
+}
+
+SEC("?fmod_ret/hid_bpf_device_event")
+int BPF_PROG(hid_change_report_id, struct hid_bpf_ctx *hid_ctx)
+{
+	__u8 *rw_data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 3 /* size */);
+
+	if (!rw_data)
+		return 0; /* EPERM check */
+
+	rw_data[0] = 2;
+
+	return 9;
 }
 
 SEC("syscall")