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/* SPDX-License-Identifier: GPL-2.0+ */
#ifndef __HID_BPF_H
#define __HID_BPF_H
#include <linux/bpf.h>
#include <linux/spinlock.h>
#include <uapi/linux/hid.h>
struct hid_device;
/*
* The following is the user facing HID BPF API.
*
* Extra care should be taken when editing this part, as
* it might break existing out of the tree bpf programs.
*/
/**
* struct hid_bpf_ctx - User accessible data for all HID programs
*
* ``data`` is not directly accessible from the context. We need to issue
* a call to ``hid_bpf_get_data()`` in order to get a pointer to that field.
*
* All of these fields are currently read-only.
*
* @index: program index in the jump table. No special meaning (a smaller index
* doesn't mean the program will be executed before another program with
* a bigger index).
* @hid: the ``struct hid_device`` representing the device itself
* @report_type: used for ``hid_bpf_device_event()``
* @allocated_size: Allocated size of data.
*
* This is how much memory is available and can be requested
* by the HID program.
* Note that for ``HID_BPF_RDESC_FIXUP``, that memory is set to
* ``4096`` (4 KB)
* @size: Valid data in the data field.
*
* Programs can get the available valid size in data by fetching this field.
* Programs can also change this value by returning a positive number in the
* program.
* To discard the event, return a negative error code.
*
* ``size`` must always be less or equal than ``allocated_size`` (it is enforced
* once all BPF programs have been run).
* @retval: Return value of the previous program.
*/
struct hid_bpf_ctx {
__u32 index;
const struct hid_device *hid;
__u32 allocated_size;
enum hid_report_type report_type;
union {
__s32 retval;
__s32 size;
};
};
/**
* enum hid_bpf_attach_flags - flags used when attaching a HIF-BPF program
*
* @HID_BPF_FLAG_NONE: no specific flag is used, the kernel choses where to
* insert the program
* @HID_BPF_FLAG_INSERT_HEAD: insert the given program before any other program
* currently attached to the device. This doesn't
* guarantee that this program will always be first
* @HID_BPF_FLAG_MAX: sentinel value, not to be used by the callers
*/
enum hid_bpf_attach_flags {
HID_BPF_FLAG_NONE = 0,
HID_BPF_FLAG_INSERT_HEAD = _BITUL(0),
HID_BPF_FLAG_MAX,
};
/* 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);
/*
* Below is HID internal
*/
/* internal function to call eBPF programs, not to be used by anybody */
int __hid_bpf_tail_call(struct hid_bpf_ctx *ctx);
#define HID_BPF_MAX_PROGS_PER_DEV 64
#define HID_BPF_FLAG_MASK (((HID_BPF_FLAG_MAX - 1) << 1) - 1)
/* types of HID programs to attach to */
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_MAX,
};
struct hid_report_enum;
struct hid_bpf_ops {
struct hid_report *(*hid_get_report)(struct hid_report_enum *report_enum, const u8 *data);
int (*hid_hw_raw_request)(struct hid_device *hdev,
unsigned char reportnum, __u8 *buf,
size_t len, enum hid_report_type rtype,
enum hid_class_request reqtype);
struct module *owner;
const struct bus_type *bus_type;
};
extern struct hid_bpf_ops *hid_bpf_ops;
struct hid_bpf_prog_list {
u16 prog_idx[HID_BPF_MAX_PROGS_PER_DEV];
u8 prog_cnt;
};
/* stored in each device */
struct hid_bpf {
u8 *device_data; /* allocated when a bpf program of type
* SEC(f.../hid_bpf_device_event) has been attached
* to this HID device
*/
u32 allocated_data;
struct hid_bpf_prog_list __rcu *progs[HID_BPF_PROG_TYPE_MAX]; /* attached BPF progs */
bool destroyed; /* prevents the assignment of any progs */
spinlock_t progs_lock; /* protects RCU update of progs */
};
/* specific HID-BPF link when a program is attached to a device */
struct hid_bpf_link {
struct bpf_link link;
int hid_table_index;
};
#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);
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);
void hid_bpf_device_init(struct hid_device *hid);
u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size);
#else /* CONFIG_HID_BPF */
static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type,
u8 *data, u32 *size, int interrupt) { return data; }
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) {}
static inline void hid_bpf_device_init(struct hid_device *hid) {}
static inline u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size)
{
return kmemdup(rdesc, *size, GFP_KERNEL);
}
#endif /* CONFIG_HID_BPF */
#endif /* __HID_BPF_H */
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