Merge branch 'for-6.13/bpf' into for-linus

- improvement of the way hid-bpf coexists with specific drivers (others than
  hid-generic) that are already bound to devices (Benjamin Tissoires)

1 files changed, 65 insertions, 19 deletions

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 910cf0728d0d..81d6c734c8bc 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -713,7 +713,14 @@ static void hid_close_report(struct hid_device *device)
 		INIT_LIST_HEAD(&report_enum->report_list);
 	}
 
-	kfree(device->rdesc);
+	/*
+	 * If the HID driver had a rdesc_fixup() callback, dev->rdesc
+	 * will be allocated by hid-core and needs to be freed.
+	 * Otherwise, it is either equal to dev_rdesc or bpf_rdesc, in
+	 * which cases it'll be freed later on device removal or destroy.
+	 */
+	if (device->rdesc != device->dev_rdesc && device->rdesc != device->bpf_rdesc)
+		kfree(device->rdesc);
 	device->rdesc = NULL;
 	device->rsize = 0;
 
@@ -726,6 +733,14 @@ static void hid_close_report(struct hid_device *device)
 	device->status &= ~HID_STAT_PARSED;
 }
 
+static inline void hid_free_bpf_rdesc(struct hid_device *hdev)
+{
+	/* bpf_rdesc is either equal to dev_rdesc or allocated by call_hid_bpf_rdesc_fixup() */
+	if (hdev->bpf_rdesc != hdev->dev_rdesc)
+		kfree(hdev->bpf_rdesc);
+	hdev->bpf_rdesc = NULL;
+}
+
 /*
  * Free a device structure, all reports, and all fields.
  */
@@ -735,6 +750,7 @@ void hiddev_free(struct kref *ref)
 	struct hid_device *hid = container_of(ref, struct hid_device, ref);
 
 	hid_close_report(hid);
+	hid_free_bpf_rdesc(hid);
 	kfree(hid->dev_rdesc);
 	kfree(hid);
 }
@@ -1227,7 +1243,6 @@ int hid_open_report(struct hid_device *device)
 	struct hid_item item;
 	unsigned int size;
 	const __u8 *start;
-	__u8 *buf;
 	const __u8 *end;
 	const __u8 *next;
 	int ret;
@@ -1243,25 +1258,34 @@ int hid_open_report(struct hid_device *device)
 	if (WARN_ON(device->status & HID_STAT_PARSED))
 		return -EBUSY;
 
-	start = device->dev_rdesc;
+	start = device->bpf_rdesc;
 	if (WARN_ON(!start))
 		return -ENODEV;
-	size = device->dev_rsize;
+	size = device->bpf_rsize;
 
-	/* call_hid_bpf_rdesc_fixup() ensures we work on a copy of rdesc */
-	buf = call_hid_bpf_rdesc_fixup(device, start, &size);
-	if (buf == NULL)
-		return -ENOMEM;
+	if (device->driver->report_fixup) {
+		/*
+		 * device->driver->report_fixup() needs to work
+		 * on a copy of our report descriptor so it can
+		 * change it.
+		 */
+		__u8 *buf = kmemdup(start, size, GFP_KERNEL);
+
+		if (buf == NULL)
+			return -ENOMEM;
 
-	if (device->driver->report_fixup)
 		start = device->driver->report_fixup(device, buf, &size);
-	else
-		start = buf;
 
-	start = kmemdup(start, size, GFP_KERNEL);
-	kfree(buf);
-	if (start == NULL)
-		return -ENOMEM;
+		/*
+		 * The second kmemdup is required in case report_fixup() returns
+		 * a static read-only memory, but we have no idea if that memory
+		 * needs to be cleaned up or not at the end.
+		 */
+		start = kmemdup(start, size, GFP_KERNEL);
+		kfree(buf);
+		if (start == NULL)
+			return -ENOMEM;
+	}
 
 	device->rdesc = start;
 	device->rsize = size;
@@ -2656,9 +2680,10 @@ static bool hid_check_device_match(struct hid_device *hdev,
 	/*
 	 * hid-generic implements .match(), so we must be dealing with a
 	 * different HID driver here, and can simply check if
-	 * hid_ignore_special_drivers is set or not.
+	 * hid_ignore_special_drivers or HID_QUIRK_IGNORE_SPECIAL_DRIVER
+	 * are set or not.
 	 */
-	return !hid_ignore_special_drivers;
+	return !hid_ignore_special_drivers && !(hdev->quirks & HID_QUIRK_IGNORE_SPECIAL_DRIVER);
 }
 
 static int __hid_device_probe(struct hid_device *hdev, struct hid_driver *hdrv)
@@ -2666,6 +2691,27 @@ static int __hid_device_probe(struct hid_device *hdev, struct hid_driver *hdrv)
 	const struct hid_device_id *id;
 	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);
+
+		/* keep this around so we know we called it once */
+		hdev->bpf_rsize = hdev->dev_rsize;
+
+		/* 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))
 		return -ENODEV;
 
@@ -2673,8 +2719,6 @@ 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) {
@@ -2922,9 +2966,11 @@ static void hid_remove_device(struct hid_device *hdev)
 		hid_debug_unregister(hdev);
 		hdev->status &= ~HID_STAT_ADDED;
 	}
+	hid_free_bpf_rdesc(hdev);
 	kfree(hdev->dev_rdesc);
 	hdev->dev_rdesc = NULL;
 	hdev->dev_rsize = 0;
+	hdev->bpf_rsize = 0;
 }
 
 /**