linux-kernel - [PATCH HID v3 4/9] HID: bpf: allow write access to quirks field in struct hid

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Message-Id: <20241001-hid-bpf-hid-generic-v3-4-2ef1019468df@kernel.org>
Date: Tue, 01 Oct 2024 16:30:08 +0200
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 v3 4/9] HID: bpf: allow write access to quirks field in
 struct hid_device

This allows to give more control from BPF during report descriptor fixup.
We already reset the quirks before calling ->probe(), so now we reset
it once before calling hid_bpf_rdesc_fixup().

Reviewed-by: Peter Hutterer <peter.hutterer@...-t.net>
Signed-off-by: Benjamin Tissoires <bentiss@...nel.org>

---

no changes in v3

new in v2
---
 drivers/hid/bpf/hid_bpf_struct_ops.c |  1 +
 drivers/hid/hid-core.c               | 11 +++++++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/bpf/hid_bpf_struct_ops.c b/drivers/hid/bpf/hid_bpf_struct_ops.c
index 702c22fae136..0e611a9d79d7 100644
--- a/drivers/hid/bpf/hid_bpf_struct_ops.c
+++ b/drivers/hid/bpf/hid_bpf_struct_ops.c
@@ -79,6 +79,7 @@ static int hid_bpf_ops_btf_struct_access(struct bpf_verifier_log *log,
 		WRITE_RANGE(hid_device, name, true),
 		WRITE_RANGE(hid_device, uniq, true),
 		WRITE_RANGE(hid_device, phys, true),
+		WRITE_RANGE(hid_device, quirks, false),
 	};
 #undef WRITE_RANGE
 	const struct btf_type *state = NULL;
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index b0a22e173502..8e879937e956 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2709,6 +2709,12 @@ static int __hid_device_probe(struct hid_device *hdev, struct hid_driver *hdrv)
 	int ret;
 
 	if (!hdev->bpf_rsize) {
+		unsigned int quirks;
+
+		/* reset the quirks that has been previously set */
+		quirks = hid_lookup_quirk(hdev);
+		hdev->quirks = quirks;
+
 		/* in case a bpf program gets detached, we need to free the old one */
 		hid_free_bpf_rdesc(hdev);
 
@@ -2718,6 +2724,9 @@ static int __hid_device_probe(struct hid_device *hdev, struct hid_driver *hdrv)
 		/* call_hid_bpf_rdesc_fixup will always return a valid pointer */
 		hdev->bpf_rdesc = call_hid_bpf_rdesc_fixup(hdev, hdev->dev_rdesc,
 							   &hdev->bpf_rsize);
+		if (quirks ^ hdev->quirks)
+			hid_info(hdev, "HID-BPF toggled quirks on the device: %04x",
+				 quirks ^ hdev->quirks);
 	}
 
 	if (!hid_check_device_match(hdev, hdrv, &id))
@@ -2727,8 +2736,6 @@ static int __hid_device_probe(struct hid_device *hdev, struct hid_driver *hdrv)
 	if (!hdev->devres_group_id)
 		return -ENOMEM;
 
-	/* reset the quirks that has been previously set */
-	hdev->quirks = hid_lookup_quirk(hdev);
 	hdev->driver = hdrv;
 
 	if (hdrv->probe) {

-- 
2.46.0