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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/* Following functions are kfunc that we export to BPF programs */
81/* available everywhere in HID-BPF */
82__u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx, unsigned int offset, const size_t __sz);
83
84/* only available in syscall */
85int hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags);
86int hid_bpf_hw_request(struct hid_bpf_ctx *ctx, __u8 *buf, size_t buf__sz,
87 enum hid_report_type rtype, enum hid_class_request reqtype);
88struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id);
89void hid_bpf_release_context(struct hid_bpf_ctx *ctx);
90
91/*
92 * Below is HID internal
93 */
94
95/* internal function to call eBPF programs, not to be used by anybody */
96int __hid_bpf_tail_call(struct hid_bpf_ctx *ctx);
97
98#define HID_BPF_MAX_PROGS_PER_DEV 64
99#define HID_BPF_FLAG_MASK (((HID_BPF_FLAG_MAX - 1) << 1) - 1)
100
101/* types of HID programs to attach to */
102enum hid_bpf_prog_type {
103 HID_BPF_PROG_TYPE_UNDEF = -1,
104 HID_BPF_PROG_TYPE_DEVICE_EVENT, /* an event is emitted from the device */
105 HID_BPF_PROG_TYPE_RDESC_FIXUP,
106 HID_BPF_PROG_TYPE_MAX,
107};
108
109struct hid_report_enum;
110
111struct hid_bpf_ops {
112 struct hid_report *(*hid_get_report)(struct hid_report_enum *report_enum, const u8 *data);
113 int (*hid_hw_raw_request)(struct hid_device *hdev,
114 unsigned char reportnum, __u8 *buf,
115 size_t len, enum hid_report_type rtype,
116 enum hid_class_request reqtype);
117 struct module *owner;
118 struct bus_type *bus_type;
119};
120
121extern struct hid_bpf_ops *hid_bpf_ops;
122
123struct hid_bpf_prog_list {
124 u16 prog_idx[HID_BPF_MAX_PROGS_PER_DEV];
125 u8 prog_cnt;
126};
127
128/* stored in each device */
129struct hid_bpf {
130 u8 *device_data; /* allocated when a bpf program of type
131 * SEC(f.../hid_bpf_device_event) has been attached
132 * to this HID device
133 */
134 u32 allocated_data;
135
136 struct hid_bpf_prog_list __rcu *progs[HID_BPF_PROG_TYPE_MAX]; /* attached BPF progs */
137 bool destroyed; /* prevents the assignment of any progs */
138
139 spinlock_t progs_lock; /* protects RCU update of progs */
140};
141
142/* specific HID-BPF link when a program is attached to a device */
143struct hid_bpf_link {
144 struct bpf_link link;
145 int hid_table_index;
146};
147
148#ifdef CONFIG_HID_BPF
149u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data,
150 u32 *size, int interrupt);
151int hid_bpf_connect_device(struct hid_device *hdev);
152void hid_bpf_disconnect_device(struct hid_device *hdev);
153void hid_bpf_destroy_device(struct hid_device *hid);
154void hid_bpf_device_init(struct hid_device *hid);
155u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size);
156#else /* CONFIG_HID_BPF */
157static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type,
158 u8 *data, u32 *size, int interrupt) { return data; }
159static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; }
160static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {}
161static inline void hid_bpf_destroy_device(struct hid_device *hid) {}
162static inline void hid_bpf_device_init(struct hid_device *hid) {}
163static inline u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size)
164{
165 return kmemdup(rdesc, *size, GFP_KERNEL);
166}
167
168#endif /* CONFIG_HID_BPF */
169
170#endif /* __HID_BPF_H */