linux-kernel - [PATCH bpf-next v2 19/28] bpf/hid: add bpf_hid_raw

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Message-Id: <20220304172852.274126-20-benjamin.tissoires@redhat.com>
Date:   Fri,  4 Mar 2022 18:28:43 +0100
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Jiri Kosina <jikos@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, Shuah Khan <shuah@...nel.org>,
        Dave Marchevsky <davemarchevsky@...com>,
        Joe Stringer <joe@...ium.io>
Cc:     Tero Kristo <tero.kristo@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Subject: [PATCH bpf-next v2 19/28] bpf/hid: add bpf_hid_raw_request helper function

When we are in a user_event context, we can talk to the device to fetch
or set features/outputs/inputs reports.
Add a bpf helper to do so. This helper is thus only available to
user_events, because calling this function while in IRQ context (any
other BPF type) is forbidden.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>

---

changes in v2:
- split the series by bpf/libbpf/hid/selftests and samples
---
 include/linux/bpf-hid.h        |  2 ++
 include/uapi/linux/bpf.h       |  8 ++++++++
 kernel/bpf/hid.c               | 26 ++++++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  8 ++++++++
 4 files changed, 44 insertions(+)

diff --git a/include/linux/bpf-hid.h b/include/linux/bpf-hid.h
index 4cf2e99109fe..bd548f6a4a26 100644
--- a/include/linux/bpf-hid.h
+++ b/include/linux/bpf-hid.h
@@ -100,6 +100,8 @@ struct bpf_hid_hooks {
 			    u64 offset, u32 n, u8 *data, u64 data_size);
 	int (*hid_set_data)(struct hid_device *hdev, u8 *buf, size_t buf_size,
 			    u64 offset, u32 n, u8 *data, u64 data_size);
+	int (*hid_raw_request)(struct hid_device *hdev, u8 *buf, size_t size,
+			       u8 rtype, u8 reqtype);
 };
 
 #ifdef CONFIG_BPF
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b3063384d380..417cf1c31579 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5121,6 +5121,13 @@ union bpf_attr {
  *	Return
  *		The length of data copied into ctx->event.data. On error, a negative
  *		value is returned.
+ *
+ * int bpf_hid_raw_request(void *ctx, void *buf, u64 size, u8 rtype, u8 reqtype)
+ *	Description
+ *		communicate with the HID device
+ *	Return
+ *		0 on success.
+ *		negative value on error.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5317,6 +5324,7 @@ union bpf_attr {
 	FN(copy_from_user_task),	\
 	FN(hid_get_data),		\
 	FN(hid_set_data),		\
+	FN(hid_raw_request),		\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/hid.c b/kernel/bpf/hid.c
index de003dbd7d01..653d10c0f4e6 100644
--- a/kernel/bpf/hid.c
+++ b/kernel/bpf/hid.c
@@ -86,6 +86,28 @@ static const struct bpf_func_proto bpf_hid_set_data_proto = {
 	.arg5_type = ARG_CONST_SIZE_OR_ZERO,
 };
 
+BPF_CALL_5(bpf_hid_raw_request, void*, ctx, void*, buf, u64, size,
+	   u8, rtype, u8, reqtype)
+{
+	struct hid_bpf_ctx *bpf_ctx = ctx;
+
+	if (!hid_hooks.hid_raw_request)
+		return -EOPNOTSUPP;
+
+	return hid_hooks.hid_raw_request(bpf_ctx->hdev, buf, size, rtype, reqtype);
+}
+
+static const struct bpf_func_proto bpf_hid_raw_request_proto = {
+	.func      = bpf_hid_raw_request,
+	.gpl_only  = true, /* hid_raw_request is EXPORT_SYMBOL_GPL */
+	.ret_type  = RET_INTEGER,
+	.arg1_type = ARG_PTR_TO_CTX,
+	.arg2_type = ARG_PTR_TO_MEM,
+	.arg3_type = ARG_CONST_SIZE_OR_ZERO,
+	.arg4_type = ARG_ANYTHING,
+	.arg5_type = ARG_ANYTHING,
+};
+
 static const struct bpf_func_proto *
 hid_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
@@ -94,6 +116,10 @@ hid_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_hid_get_data_proto;
 	case BPF_FUNC_hid_set_data:
 		return &bpf_hid_set_data_proto;
+	case BPF_FUNC_hid_raw_request:
+		if (prog->expected_attach_type != BPF_HID_DEVICE_EVENT)
+			return &bpf_hid_raw_request_proto;
+		return NULL;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index b3063384d380..417cf1c31579 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5121,6 +5121,13 @@ union bpf_attr {
  *	Return
  *		The length of data copied into ctx->event.data. On error, a negative
  *		value is returned.
+ *
+ * int bpf_hid_raw_request(void *ctx, void *buf, u64 size, u8 rtype, u8 reqtype)
+ *	Description
+ *		communicate with the HID device
+ *	Return
+ *		0 on success.
+ *		negative value on error.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5317,6 +5324,7 @@ union bpf_attr {
 	FN(copy_from_user_task),	\
 	FN(hid_get_data),		\
 	FN(hid_set_data),		\
+	FN(hid_raw_request),		\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
-- 
2.35.1