[PATCH bpf-next v2 19/28] bpf/hid: add bpf_hid_raw_request helper function

Benjamin Tissoires
2022-03-04T17:35:04Z

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@redhat.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