1f5c27da4SBenjamin Tissoires /* SPDX-License-Identifier: GPL-2.0+ */
2f5c27da4SBenjamin Tissoires
3f5c27da4SBenjamin Tissoires #ifndef __HID_BPF_H
4f5c27da4SBenjamin Tissoires #define __HID_BPF_H
5f5c27da4SBenjamin Tissoires
6*4b9a3f49SBenjamin Tissoires #include <linux/bpf.h>
7f5c27da4SBenjamin Tissoires #include <linux/spinlock.h>
8f5c27da4SBenjamin Tissoires #include <uapi/linux/hid.h>
9f5c27da4SBenjamin Tissoires
10f5c27da4SBenjamin Tissoires struct hid_device;
11f5c27da4SBenjamin Tissoires
12f5c27da4SBenjamin Tissoires /*
13f5c27da4SBenjamin Tissoires * The following is the user facing HID BPF API.
14f5c27da4SBenjamin Tissoires *
15f5c27da4SBenjamin Tissoires * Extra care should be taken when editing this part, as
16f5c27da4SBenjamin Tissoires * it might break existing out of the tree bpf programs.
17f5c27da4SBenjamin Tissoires */
18f5c27da4SBenjamin Tissoires
19f5c27da4SBenjamin Tissoires /**
20f5c27da4SBenjamin Tissoires * struct hid_bpf_ctx - User accessible data for all HID programs
21f5c27da4SBenjamin Tissoires *
22f5c27da4SBenjamin Tissoires * ``data`` is not directly accessible from the context. We need to issue
23f5c27da4SBenjamin Tissoires * a call to ``hid_bpf_get_data()`` in order to get a pointer to that field.
24f5c27da4SBenjamin Tissoires *
25f5c27da4SBenjamin Tissoires * All of these fields are currently read-only.
26f5c27da4SBenjamin Tissoires *
27f5c27da4SBenjamin Tissoires * @index: program index in the jump table. No special meaning (a smaller index
28f5c27da4SBenjamin Tissoires * doesn't mean the program will be executed before another program with
29f5c27da4SBenjamin Tissoires * a bigger index).
30f5c27da4SBenjamin Tissoires * @hid: the ``struct hid_device`` representing the device itself
31f5c27da4SBenjamin Tissoires * @report_type: used for ``hid_bpf_device_event()``
32658ee5a6SBenjamin Tissoires * @allocated_size: Allocated size of data.
33658ee5a6SBenjamin Tissoires *
34658ee5a6SBenjamin Tissoires * This is how much memory is available and can be requested
35658ee5a6SBenjamin Tissoires * by the HID program.
36658ee5a6SBenjamin Tissoires * Note that for ``HID_BPF_RDESC_FIXUP``, that memory is set to
37658ee5a6SBenjamin Tissoires * ``4096`` (4 KB)
38f5c27da4SBenjamin Tissoires * @size: Valid data in the data field.
39f5c27da4SBenjamin Tissoires *
40f5c27da4SBenjamin Tissoires * Programs can get the available valid size in data by fetching this field.
41658ee5a6SBenjamin Tissoires * Programs can also change this value by returning a positive number in the
42658ee5a6SBenjamin Tissoires * program.
43658ee5a6SBenjamin Tissoires * To discard the event, return a negative error code.
44658ee5a6SBenjamin Tissoires *
45658ee5a6SBenjamin Tissoires * ``size`` must always be less or equal than ``allocated_size`` (it is enforced
46658ee5a6SBenjamin Tissoires * once all BPF programs have been run).
47658ee5a6SBenjamin Tissoires * @retval: Return value of the previous program.
48f5c27da4SBenjamin Tissoires */
49f5c27da4SBenjamin Tissoires struct hid_bpf_ctx {
50f5c27da4SBenjamin Tissoires __u32 index;
51f5c27da4SBenjamin Tissoires const struct hid_device *hid;
52658ee5a6SBenjamin Tissoires __u32 allocated_size;
53f5c27da4SBenjamin Tissoires enum hid_report_type report_type;
54658ee5a6SBenjamin Tissoires union {
55658ee5a6SBenjamin Tissoires __s32 retval;
56f5c27da4SBenjamin Tissoires __s32 size;
57f5c27da4SBenjamin Tissoires };
58658ee5a6SBenjamin Tissoires };
59f5c27da4SBenjamin Tissoires
60f5c27da4SBenjamin Tissoires /**
61f5c27da4SBenjamin Tissoires * enum hid_bpf_attach_flags - flags used when attaching a HIF-BPF program
62f5c27da4SBenjamin Tissoires *
63f5c27da4SBenjamin Tissoires * @HID_BPF_FLAG_NONE: no specific flag is used, the kernel choses where to
64f5c27da4SBenjamin Tissoires * insert the program
65f5c27da4SBenjamin Tissoires * @HID_BPF_FLAG_INSERT_HEAD: insert the given program before any other program
66f5c27da4SBenjamin Tissoires * currently attached to the device. This doesn't
67f5c27da4SBenjamin Tissoires * guarantee that this program will always be first
68f5c27da4SBenjamin Tissoires * @HID_BPF_FLAG_MAX: sentinel value, not to be used by the callers
69f5c27da4SBenjamin Tissoires */
70f5c27da4SBenjamin Tissoires enum hid_bpf_attach_flags {
71f5c27da4SBenjamin Tissoires HID_BPF_FLAG_NONE = 0,
72f5c27da4SBenjamin Tissoires HID_BPF_FLAG_INSERT_HEAD = _BITUL(0),
73f5c27da4SBenjamin Tissoires HID_BPF_FLAG_MAX,
74f5c27da4SBenjamin Tissoires };
75f5c27da4SBenjamin Tissoires
76f5c27da4SBenjamin Tissoires /* Following functions are tracepoints that BPF programs can attach to */
77f5c27da4SBenjamin Tissoires int hid_bpf_device_event(struct hid_bpf_ctx *ctx);
78ad190df1SBenjamin Tissoires int hid_bpf_rdesc_fixup(struct hid_bpf_ctx *ctx);
79f5c27da4SBenjamin Tissoires
80f5c27da4SBenjamin Tissoires /* Following functions are kfunc that we export to BPF programs */
8191a7f802SBenjamin Tissoires /* available everywhere in HID-BPF */
82f5c27da4SBenjamin Tissoires __u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx, unsigned int offset, const size_t __sz);
83f5c27da4SBenjamin Tissoires
84f5c27da4SBenjamin Tissoires /* only available in syscall */
85f5c27da4SBenjamin Tissoires int hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags);
8691a7f802SBenjamin Tissoires int hid_bpf_hw_request(struct hid_bpf_ctx *ctx, __u8 *buf, size_t buf__sz,
8791a7f802SBenjamin Tissoires enum hid_report_type rtype, enum hid_class_request reqtype);
8891a7f802SBenjamin Tissoires struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id);
8991a7f802SBenjamin Tissoires void hid_bpf_release_context(struct hid_bpf_ctx *ctx);
90f5c27da4SBenjamin Tissoires
91f5c27da4SBenjamin Tissoires /*
92f5c27da4SBenjamin Tissoires * Below is HID internal
93f5c27da4SBenjamin Tissoires */
94f5c27da4SBenjamin Tissoires
95f5c27da4SBenjamin Tissoires /* internal function to call eBPF programs, not to be used by anybody */
96f5c27da4SBenjamin Tissoires int __hid_bpf_tail_call(struct hid_bpf_ctx *ctx);
97f5c27da4SBenjamin Tissoires
98f5c27da4SBenjamin Tissoires #define HID_BPF_MAX_PROGS_PER_DEV 64
99f5c27da4SBenjamin Tissoires #define HID_BPF_FLAG_MASK (((HID_BPF_FLAG_MAX - 1) << 1) - 1)
100f5c27da4SBenjamin Tissoires
101f5c27da4SBenjamin Tissoires /* types of HID programs to attach to */
102f5c27da4SBenjamin Tissoires enum hid_bpf_prog_type {
103f5c27da4SBenjamin Tissoires HID_BPF_PROG_TYPE_UNDEF = -1,
104f5c27da4SBenjamin Tissoires HID_BPF_PROG_TYPE_DEVICE_EVENT, /* an event is emitted from the device */
105ad190df1SBenjamin Tissoires HID_BPF_PROG_TYPE_RDESC_FIXUP,
106f5c27da4SBenjamin Tissoires HID_BPF_PROG_TYPE_MAX,
107f5c27da4SBenjamin Tissoires };
108f5c27da4SBenjamin Tissoires
10991a7f802SBenjamin Tissoires struct hid_report_enum;
11091a7f802SBenjamin Tissoires
111f5c27da4SBenjamin Tissoires struct hid_bpf_ops {
11291a7f802SBenjamin Tissoires struct hid_report *(*hid_get_report)(struct hid_report_enum *report_enum, const u8 *data);
11391a7f802SBenjamin Tissoires int (*hid_hw_raw_request)(struct hid_device *hdev,
11491a7f802SBenjamin Tissoires unsigned char reportnum, __u8 *buf,
11591a7f802SBenjamin Tissoires size_t len, enum hid_report_type rtype,
11691a7f802SBenjamin Tissoires enum hid_class_request reqtype);
117f5c27da4SBenjamin Tissoires struct module *owner;
118f5c27da4SBenjamin Tissoires struct bus_type *bus_type;
119f5c27da4SBenjamin Tissoires };
120f5c27da4SBenjamin Tissoires
121f5c27da4SBenjamin Tissoires extern struct hid_bpf_ops *hid_bpf_ops;
122f5c27da4SBenjamin Tissoires
123f5c27da4SBenjamin Tissoires struct hid_bpf_prog_list {
124f5c27da4SBenjamin Tissoires u16 prog_idx[HID_BPF_MAX_PROGS_PER_DEV];
125f5c27da4SBenjamin Tissoires u8 prog_cnt;
126f5c27da4SBenjamin Tissoires };
127f5c27da4SBenjamin Tissoires
128f5c27da4SBenjamin Tissoires /* stored in each device */
129f5c27da4SBenjamin Tissoires struct hid_bpf {
130658ee5a6SBenjamin Tissoires u8 *device_data; /* allocated when a bpf program of type
131658ee5a6SBenjamin Tissoires * SEC(f.../hid_bpf_device_event) has been attached
132658ee5a6SBenjamin Tissoires * to this HID device
133658ee5a6SBenjamin Tissoires */
134658ee5a6SBenjamin Tissoires u32 allocated_data;
135658ee5a6SBenjamin Tissoires
136f5c27da4SBenjamin Tissoires struct hid_bpf_prog_list __rcu *progs[HID_BPF_PROG_TYPE_MAX]; /* attached BPF progs */
137f5c27da4SBenjamin Tissoires bool destroyed; /* prevents the assignment of any progs */
138f5c27da4SBenjamin Tissoires
139f5c27da4SBenjamin Tissoires spinlock_t progs_lock; /* protects RCU update of progs */
140f5c27da4SBenjamin Tissoires };
141f5c27da4SBenjamin Tissoires
142*4b9a3f49SBenjamin Tissoires /* specific HID-BPF link when a program is attached to a device */
143*4b9a3f49SBenjamin Tissoires struct hid_bpf_link {
144*4b9a3f49SBenjamin Tissoires struct bpf_link link;
145*4b9a3f49SBenjamin Tissoires int hid_table_index;
146*4b9a3f49SBenjamin Tissoires };
147*4b9a3f49SBenjamin Tissoires
148f5c27da4SBenjamin Tissoires #ifdef CONFIG_HID_BPF
149658ee5a6SBenjamin Tissoires u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data,
150658ee5a6SBenjamin Tissoires u32 *size, int interrupt);
151658ee5a6SBenjamin Tissoires int hid_bpf_connect_device(struct hid_device *hdev);
152658ee5a6SBenjamin Tissoires void hid_bpf_disconnect_device(struct hid_device *hdev);
153f5c27da4SBenjamin Tissoires void hid_bpf_destroy_device(struct hid_device *hid);
154f5c27da4SBenjamin Tissoires void hid_bpf_device_init(struct hid_device *hid);
155ad190df1SBenjamin Tissoires u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size);
156f5c27da4SBenjamin Tissoires #else /* CONFIG_HID_BPF */
dispatch_hid_bpf_device_event(struct hid_device * hid,enum hid_report_type type,u8 * data,u32 * size,int interrupt)157658ee5a6SBenjamin Tissoires static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type,
158576e619bSBenjamin Tissoires u8 *data, u32 *size, int interrupt) { return data; }
hid_bpf_connect_device(struct hid_device * hdev)159658ee5a6SBenjamin Tissoires static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; }
hid_bpf_disconnect_device(struct hid_device * hdev)160658ee5a6SBenjamin Tissoires static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {}
hid_bpf_destroy_device(struct hid_device * hid)161f5c27da4SBenjamin Tissoires static inline void hid_bpf_destroy_device(struct hid_device *hid) {}
hid_bpf_device_init(struct hid_device * hid)162f5c27da4SBenjamin Tissoires static inline void hid_bpf_device_init(struct hid_device *hid) {}
call_hid_bpf_rdesc_fixup(struct hid_device * hdev,u8 * rdesc,unsigned int * size)163ad190df1SBenjamin Tissoires static inline u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size)
164ad190df1SBenjamin Tissoires {
165ad190df1SBenjamin Tissoires return kmemdup(rdesc, *size, GFP_KERNEL);
166ad190df1SBenjamin Tissoires }
167ad190df1SBenjamin Tissoires
168f5c27da4SBenjamin Tissoires #endif /* CONFIG_HID_BPF */
169f5c27da4SBenjamin Tissoires
170f5c27da4SBenjamin Tissoires #endif /* __HID_BPF_H */
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