1/* SPDX-License-Identifier: GPL-2.0+ */ 2 3#ifndef __HID_BPF_H 4#define __HID_BPF_H 5 6#include <linux/bpf.h> 7#include <linux/spinlock.h> 8#include <uapi/linux/hid.h> 9 10struct hid_device; 11 12/* 13 * The following is the user facing HID BPF API. 14 * 15 * Extra care should be taken when editing this part, as 16 * it might break existing out of the tree bpf programs. 17 */ 18 19/** 20 * struct hid_bpf_ctx - User accessible data for all HID programs 21 * 22 * ``data`` is not directly accessible from the context. We need to issue 23 * a call to ``hid_bpf_get_data()`` in order to get a pointer to that field. 24 * 25 * All of these fields are currently read-only. 26 * 27 * @index: program index in the jump table. No special meaning (a smaller index 28 * doesn't mean the program will be executed before another program with 29 * a bigger index). 30 * @hid: the ``struct hid_device`` representing the device itself 31 * @report_type: used for ``hid_bpf_device_event()`` 32 * @allocated_size: Allocated size of data. 33 * 34 * This is how much memory is available and can be requested 35 * by the HID program. 36 * Note that for ``HID_BPF_RDESC_FIXUP``, that memory is set to 37 * ``4096`` (4 KB) 38 * @size: Valid data in the data field. 39 * 40 * Programs can get the available valid size in data by fetching this field. 41 * Programs can also change this value by returning a positive number in the 42 * program. 43 * To discard the event, return a negative error code. 44 * 45 * ``size`` must always be less or equal than ``allocated_size`` (it is enforced 46 * once all BPF programs have been run). 47 * @retval: Return value of the previous program. 48 */ 49struct hid_bpf_ctx { 50 __u32 index; 51 const struct hid_device *hid; 52 __u32 allocated_size; 53 enum hid_report_type report_type; 54 union { 55 __s32 retval; 56 __s32 size; 57 }; 58}; 59 60/** 61 * enum hid_bpf_attach_flags - flags used when attaching a HIF-BPF program 62 * 63 * @HID_BPF_FLAG_NONE: no specific flag is used, the kernel choses where to 64 * insert the program 65 * @HID_BPF_FLAG_INSERT_HEAD: insert the given program before any other program 66 * currently attached to the device. This doesn't 67 * guarantee that this program will always be first 68 * @HID_BPF_FLAG_MAX: sentinel value, not to be used by the callers 69 */ 70enum hid_bpf_attach_flags { 71 HID_BPF_FLAG_NONE = 0, 72 HID_BPF_FLAG_INSERT_HEAD = _BITUL(0), 73 HID_BPF_FLAG_MAX, 74}; 75 76/* Following functions are tracepoints that BPF programs can attach to */ 77int hid_bpf_device_event(struct hid_bpf_ctx *ctx); 78int hid_bpf_rdesc_fixup(struct hid_bpf_ctx *ctx); 79 80/* 81 * Below is HID internal 82 */ 83 84/* internal function to call eBPF programs, not to be used by anybody */ 85int __hid_bpf_tail_call(struct hid_bpf_ctx *ctx); 86 87#define HID_BPF_MAX_PROGS_PER_DEV 64 88#define HID_BPF_FLAG_MASK (((HID_BPF_FLAG_MAX - 1) << 1) - 1) 89 90/* types of HID programs to attach to */ 91enum hid_bpf_prog_type { 92 HID_BPF_PROG_TYPE_UNDEF = -1, 93 HID_BPF_PROG_TYPE_DEVICE_EVENT, /* an event is emitted from the device */ 94 HID_BPF_PROG_TYPE_RDESC_FIXUP, 95 HID_BPF_PROG_TYPE_MAX, 96}; 97 98struct hid_report_enum; 99 100struct hid_bpf_ops { 101 struct hid_report *(*hid_get_report)(struct hid_report_enum *report_enum, const u8 *data); 102 int (*hid_hw_raw_request)(struct hid_device *hdev, 103 unsigned char reportnum, __u8 *buf, 104 size_t len, enum hid_report_type rtype, 105 enum hid_class_request reqtype); 106 struct module *owner; 107 const struct bus_type *bus_type; 108}; 109 110extern struct hid_bpf_ops *hid_bpf_ops; 111 112struct hid_bpf_prog_list { 113 u16 prog_idx[HID_BPF_MAX_PROGS_PER_DEV]; 114 u8 prog_cnt; 115}; 116 117/* stored in each device */ 118struct hid_bpf { 119 u8 *device_data; /* allocated when a bpf program of type 120 * SEC(f.../hid_bpf_device_event) has been attached 121 * to this HID device 122 */ 123 u32 allocated_data; 124 125 struct hid_bpf_prog_list __rcu *progs[HID_BPF_PROG_TYPE_MAX]; /* attached BPF progs */ 126 bool destroyed; /* prevents the assignment of any progs */ 127 128 spinlock_t progs_lock; /* protects RCU update of progs */ 129}; 130 131/* specific HID-BPF link when a program is attached to a device */ 132struct hid_bpf_link { 133 struct bpf_link link; 134 int hid_table_index; 135}; 136 137#ifdef CONFIG_HID_BPF 138u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data, 139 u32 *size, int interrupt); 140int hid_bpf_connect_device(struct hid_device *hdev); 141void hid_bpf_disconnect_device(struct hid_device *hdev); 142void hid_bpf_destroy_device(struct hid_device *hid); 143void hid_bpf_device_init(struct hid_device *hid); 144u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size); 145#else /* CONFIG_HID_BPF */ 146static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, 147 u8 *data, u32 *size, int interrupt) { return data; } 148static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; } 149static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {} 150static inline void hid_bpf_destroy_device(struct hid_device *hid) {} 151static inline void hid_bpf_device_init(struct hid_device *hid) {} 152static inline u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size) 153{ 154 return kmemdup(rdesc, *size, GFP_KERNEL); 155} 156 157#endif /* CONFIG_HID_BPF */ 158 159#endif /* __HID_BPF_H */ 160