linux-kernel - [PATCH HID v2 10/11] HID: add quirk to prevent hid-input to be used

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Message-Id: <20240910-hid-bpf-hid-generic-v2-10-083dfc189e97@kernel.org>
Date: Tue, 10 Sep 2024 23:43:46 +0900
From: Benjamin Tissoires <bentiss@...nel.org>
To: Jiri Kosina <jikos@...nel.org>, 
 Peter Hutterer <peter.hutterer@...-t.net>, Vicki Pfau <vi@...rift.com>, 
 Shuah Khan <shuah@...nel.org>
Cc: linux-input@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, bpf@...r.kernel.org, 
 Benjamin Tissoires <bentiss@...nel.org>
Subject: [PATCH HID v2 10/11] HID: add quirk to prevent hid-input to be
 used

This is useful when you want to handle the device entirely from BPF
without exposing the automatic input nodes.

This is useful in case we want to have a third party program that directly
talks to the hidraw node and we don't want regular input events to be
emitted. This third party program can load a BPF program that instructs
hid-generic to rebind on the device with hidraw only and then open the
hidraw node itself.

When the application is closed, the BPF program is unloaded and the normal
driver takes back the control of the device.

Signed-off-by: Benjamin Tissoires <bentiss@...nel.org>

---

changes in v2:
- rely on hdev->quirks instead of a new struct
---
 drivers/hid/hid-core.c | 2 ++
 include/linux/hid.h    | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index bf63e2819baf..35cefd7167aa 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2217,6 +2217,8 @@ int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
 		connect_mask |= (HID_CONNECT_HIDDEV_FORCE | HID_CONNECT_HIDDEV);
 	if (hdev->quirks & HID_QUIRK_HIDINPUT_FORCE)
 		connect_mask |= HID_CONNECT_HIDINPUT_FORCE;
+	if (hdev->quirks & HID_QUIRK_IGNORE_HIDINPUT)
+		connect_mask &= ~HID_CONNECT_HIDINPUT;
 	if (hdev->bus != BUS_USB)
 		connect_mask &= ~HID_CONNECT_HIDDEV;
 	if (hid_hiddev(hdev))
diff --git a/include/linux/hid.h b/include/linux/hid.h
index b3a9586363c9..b6bad03649f6 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -360,6 +360,7 @@ struct hid_item {
  * | @HID_QUIRK_HAVE_SPECIAL_DRIVER:
  * | @HID_QUIRK_INCREMENT_USAGE_ON_DUPLICATE:
  * | @HID_QUIRK_IGNORE_SPECIAL_DRIVER
+ * | @HID_QUIRK_IGNORE_HIDINPUT
  * | @HID_QUIRK_FULLSPEED_INTERVAL:
  * | @HID_QUIRK_NO_INIT_REPORTS:
  * | @HID_QUIRK_NO_IGNORE:
@@ -386,6 +387,7 @@ struct hid_item {
 #define HID_QUIRK_INCREMENT_USAGE_ON_DUPLICATE	BIT(20)
 #define HID_QUIRK_NOINVERT			BIT(21)
 #define HID_QUIRK_IGNORE_SPECIAL_DRIVER		BIT(22)
+#define HID_QUIRK_IGNORE_HIDINPUT		BIT(23)
 #define HID_QUIRK_FULLSPEED_INTERVAL		BIT(28)
 #define HID_QUIRK_NO_INIT_REPORTS		BIT(29)
 #define HID_QUIRK_NO_IGNORE			BIT(30)

-- 
2.46.0