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From: Benjamin Tissoires <bentiss@kernel.org>
Date: Wed, 08 May 2024 12:26:40 +0200
Subject: [PATCH RFC HID 5/7] WIP: add HID-BPF hooks for hid_hw_raw_requests
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Message-Id: <20240508-hid_bpf_async_fun-v1-5-558375a25657@kernel.org>
References: <20240508-hid_bpf_async_fun-v1-0-558375a25657@kernel.org>
In-Reply-To: <20240508-hid_bpf_async_fun-v1-0-558375a25657@kernel.org>
To: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, 
 bpf@vger.kernel.org, Benjamin Tissoires <bentiss@kernel.org>

---
 drivers/hid/bpf/hid_bpf_dispatch.c  | 51 +++++++++++++++++++++++++++++++++++++
 drivers/hid/bpf/hid_bpf_jmp_table.c |  1 +
 drivers/hid/hid-core.c              |  8 +++++-
 include/linux/hid_bpf.h             | 14 ++++++++++
 4 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/bpf/hid_bpf_dispatch.c b/drivers/hid/bpf/hid_bpf_dispatch.c
index 55c9e74c2465..7aeab3f9f2c7 100644
--- a/drivers/hid/bpf/hid_bpf_dispatch.c
+++ b/drivers/hid/bpf/hid_bpf_dispatch.c
@@ -45,6 +45,11 @@ __weak noinline int hid_bpf_device_event(struct hid_bpf_ctx *ctx)
 	return 0;
 }
 
+__weak noinline int hid_bpf_raw_request(struct hid_bpf_ctx *ctx)
+{
+	return 0;
+}
+
 u8 *
 dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type, u8 *data,
 			      u32 *size, int interrupt, u64 source)
@@ -71,6 +76,9 @@ dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type
 	memset(ctx_kern.data, 0, hdev->bpf.allocated_data);
 	memcpy(ctx_kern.data, data, *size);
 
+	if (*size)
+		ctx_kern.ctx.reportnum = data[0];
+
 	ret = hid_bpf_prog_run(hdev, HID_BPF_PROG_TYPE_DEVICE_EVENT, &ctx_kern, false);
 	if (ret < 0)
 		return ERR_PTR(ret);
@@ -86,6 +94,49 @@ dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type
 }
 EXPORT_SYMBOL_GPL(dispatch_hid_bpf_device_event);
 
+u8 *
+dispatch_hid_bpf_raw_requests(struct hid_device *hdev,
+			      unsigned char reportnum, u8 *buf,
+			      u32 *size, enum hid_report_type rtype,
+			      enum hid_class_request reqtype,
+			      u64 source)
+{
+	struct hid_bpf_ctx_kern ctx_kern = {
+		.ctx = {
+			.hid = hdev,
+			.report_type = rtype,
+			.reqtype = reqtype,
+			.allocated_size = *size,
+			.size = *size,
+			.source = source,
+			.reportnum = reportnum,
+		},
+		.data = buf,
+	};
+	int ret;
+
+	if (rtype >= HID_REPORT_TYPES)
+		return ERR_PTR(-EINVAL);
+
+	/* no program has been attached yet */
+	// if (!hdev->bpf.device_data)
+	// 	return buf;
+
+	ret = hid_bpf_prog_run(hdev, HID_BPF_PROG_TYPE_RAW_REQUEST, &ctx_kern, true);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	if (ret) {
+		if (ret > ctx_kern.ctx.allocated_size)
+			return ERR_PTR(-EINVAL);
+
+		*size = ret;
+	}
+
+	return ctx_kern.data;
+}
+EXPORT_SYMBOL_GPL(dispatch_hid_bpf_raw_requests);
+
 /**
  * hid_bpf_rdesc_fixup - Called when the probe function parses the report
  * descriptor of the HID device
diff --git a/drivers/hid/bpf/hid_bpf_jmp_table.c b/drivers/hid/bpf/hid_bpf_jmp_table.c
index 4cceff354962..e183dc2835c7 100644
--- a/drivers/hid/bpf/hid_bpf_jmp_table.c
+++ b/drivers/hid/bpf/hid_bpf_jmp_table.c
@@ -64,6 +64,7 @@ static int hid_bpf_max_programs(enum hid_bpf_prog_type type)
 {
 	switch (type) {
 	case HID_BPF_PROG_TYPE_DEVICE_EVENT:
+	case HID_BPF_PROG_TYPE_RAW_REQUEST:
 		return HID_BPF_MAX_PROGS_PER_DEV;
 	case HID_BPF_PROG_TYPE_RDESC_FIXUP:
 		return 1;
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index b8414ce62e7b..7d468f6dbefe 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2407,6 +2407,7 @@ int __hid_hw_raw_request(struct hid_device *hdev,
 			 __u64 source)
 {
 	unsigned int max_buffer_size = HID_MAX_BUFFER_SIZE;
+	u32 size = (u32)len; /* max_buffer_size is 16 KB */
 
 	if (hdev->ll_driver->max_buffer_size)
 		max_buffer_size = hdev->ll_driver->max_buffer_size;
@@ -2414,7 +2415,12 @@ int __hid_hw_raw_request(struct hid_device *hdev,
 	if (len < 1 || len > max_buffer_size || !buf)
 		return -EINVAL;
 
-	return hdev->ll_driver->raw_request(hdev, reportnum, buf, len,
+	buf = dispatch_hid_bpf_raw_requests(hdev, reportnum, buf, &size, rtype,
+			      reqtype, source);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	return hdev->ll_driver->raw_request(hdev, reportnum, buf, size,
 					    rtype, reqtype);
 }
 
diff --git a/include/linux/hid_bpf.h b/include/linux/hid_bpf.h
index 6bcaf19f1cc2..1cd36bfdd608 100644
--- a/include/linux/hid_bpf.h
+++ b/include/linux/hid_bpf.h
@@ -52,10 +52,12 @@ struct hid_bpf_ctx {
 	__u64 source;
 	const struct hid_device *hid;
 	enum hid_report_type report_type;
+	enum hid_class_request reqtype; /* for HID_BPF_PROG_TYPE_RAW_REQUEST */
 	union {
 		__s32 retval;
 		__s32 size;
 	};
+	__u8 reportnum;
 };
 
 /**
@@ -77,6 +79,7 @@ enum hid_bpf_attach_flags {
 /* Following functions are tracepoints that BPF programs can attach to */
 int hid_bpf_device_event(struct hid_bpf_ctx *ctx);
 int hid_bpf_rdesc_fixup(struct hid_bpf_ctx *ctx);
+int hid_bpf_raw_request(struct hid_bpf_ctx *ctx);
 
 /*
  * Below is HID internal
@@ -90,6 +93,7 @@ enum hid_bpf_prog_type {
 	HID_BPF_PROG_TYPE_UNDEF = -1,
 	HID_BPF_PROG_TYPE_DEVICE_EVENT,			/* an event is emitted from the device */
 	HID_BPF_PROG_TYPE_RDESC_FIXUP,
+	HID_BPF_PROG_TYPE_RAW_REQUEST,
 	HID_BPF_PROG_TYPE_MAX,
 };
 
@@ -140,6 +144,11 @@ struct hid_bpf_link {
 #ifdef CONFIG_HID_BPF
 u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data,
 				  u32 *size, int interrupt, u64 source);
+u8 *dispatch_hid_bpf_raw_requests(struct hid_device *hdev,
+				  unsigned char reportnum, __u8 *buf,
+				  u32 *size, enum hid_report_type rtype,
+				  enum hid_class_request reqtype,
+				  __u64 source);
 int hid_bpf_connect_device(struct hid_device *hdev);
 void hid_bpf_disconnect_device(struct hid_device *hdev);
 void hid_bpf_destroy_device(struct hid_device *hid);
@@ -149,6 +158,11 @@ u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *s
 static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type,
 						u8 *data, u32 *size, int interrupt,
 						u64 source) { return data; }
+static inline u8 *dispatch_hid_bpf_raw_requests(struct hid_device *hdev,
+						unsigned char reportnum, u8 *buf,
+						u32 *size, enum hid_report_type rtype,
+						enum hid_class_request reqtype,
+						u64 source) { return buf; }
 static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; }
 static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {}
 static inline void hid_bpf_destroy_device(struct hid_device *hid) {}

-- 
2.44.0