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@who-t.net>
Link: https://patch.msgid.link/20241001-hid-bpf-hid-generic-v3-4-2ef1019468df@kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

diff --git a/drivers/hid/bpf/hid_bpf_struct_ops.c b/drivers/hid/bpf/hid_bpf_struct_ops.c
index 702c22f..0e611a9 100644 (file)
--- 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 b0a22e1..8e87993 100644 (file)
--- 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) {