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/mutex.h> 8 #include <linux/srcu.h> 9 #include <uapi/linux/hid.h> 10 11 struct hid_device; 12 13 /* 14 * The following is the user facing HID BPF API. 15 * 16 * Extra care should be taken when editing this part, as 17 * it might break existing out of the tree bpf programs. 18 */ 19 20 /** 21 * struct hid_bpf_ctx - User accessible data for all HID programs 22 * 23 * ``data`` is not directly accessible from the context. We need to issue 24 * a call to hid_bpf_get_data() in order to get a pointer to that field. 25 * 26 * @hid: the &struct hid_device representing the device itself 27 * @allocated_size: Allocated size of data. 28 * 29 * This is how much memory is available and can be requested 30 * by the HID program. 31 * Note that for ``HID_BPF_RDESC_FIXUP``, that memory is set to 32 * ``4096`` (4 KB) 33 * @size: Valid data in the data field. 34 * 35 * Programs can get the available valid size in data by fetching this field. 36 * Programs can also change this value by returning a positive number in the 37 * program. 38 * To discard the event, return a negative error code. 39 * 40 * ``size`` must always be less or equal than ``allocated_size`` (it is enforced 41 * once all BPF programs have been run). 42 * @retval: Return value of the previous program. 43 * 44 * ``hid`` and ``allocated_size`` are read-only, ``size`` and ``retval`` are read-write. 45 */ 46 struct hid_bpf_ctx { 47 struct hid_device *hid; 48 __u32 allocated_size; 49 union { 50 __s32 retval; 51 __s32 size; 52 }; 53 }; 54 55 /* 56 * Below is HID internal 57 */ 58 59 #define HID_BPF_MAX_PROGS_PER_DEV 64 60 #define HID_BPF_FLAG_MASK (((HID_BPF_FLAG_MAX - 1) << 1) - 1) 61 62 63 struct hid_report_enum; 64 65 struct hid_ops { 66 struct hid_report *(*hid_get_report)(struct hid_report_enum *report_enum, const u8 *data); 67 int (*hid_hw_raw_request)(struct hid_device *hdev, 68 unsigned char reportnum, __u8 *buf, 69 size_t len, enum hid_report_type rtype, 70 enum hid_class_request reqtype, 71 __u64 source, bool from_bpf); 72 int (*hid_hw_output_report)(struct hid_device *hdev, __u8 *buf, size_t len, 73 __u64 source, bool from_bpf); 74 int (*hid_input_report)(struct hid_device *hid, enum hid_report_type type, 75 u8 *data, u32 size, int interrupt, u64 source); 76 struct module *owner; 77 const struct bus_type *bus_type; 78 }; 79 80 extern struct hid_ops *hid_ops; 81 82 /** 83 * struct hid_bpf_ops - A BPF struct_ops of callbacks allowing to attach HID-BPF 84 * programs to a HID device 85 * @hid_id: the HID uniq ID to attach to. This is writeable before ``load()``, and 86 * cannot be changed after 87 * @flags: flags used while attaching the struct_ops to the device. Currently only 88 * available value is %0 or ``BPF_F_BEFORE``. 89 * Writeable only before ``load()`` 90 */ 91 struct hid_bpf_ops { 92 /* hid_id needs to stay first so we can easily change it 93 * from userspace. 94 */ 95 int hid_id; 96 u32 flags; 97 98 /* private: do not show up in the docs */ 99 struct list_head list; 100 101 /* public: rest should show up in the docs */ 102 103 /** 104 * @hid_device_event: called whenever an event is coming in from the device 105 * 106 * It has the following arguments: 107 * 108 * ``ctx``: The HID-BPF context as &struct hid_bpf_ctx 109 * 110 * Return: %0 on success and keep processing; a positive 111 * value to change the incoming size buffer; a negative 112 * error code to interrupt the processing of this event 113 * 114 * Context: Interrupt context. 115 */ 116 int (*hid_device_event)(struct hid_bpf_ctx *ctx, enum hid_report_type report_type, 117 __u64 source); 118 119 /** 120 * @hid_rdesc_fixup: called when the probe function parses the report descriptor 121 * of the HID device 122 * 123 * It has the following arguments: 124 * 125 * ``ctx``: The HID-BPF context as &struct hid_bpf_ctx 126 * 127 * Return: %0 on success and keep processing; a positive 128 * value to change the incoming size buffer; a negative 129 * error code to interrupt the processing of this device 130 */ 131 int (*hid_rdesc_fixup)(struct hid_bpf_ctx *ctx); 132 133 /** 134 * @hid_hw_request: called whenever a hid_hw_raw_request() call is emitted 135 * on the HID device 136 * 137 * It has the following arguments: 138 * 139 * ``ctx``: The HID-BPF context as &struct hid_bpf_ctx 140 * ``reportnum``: the report number, as in hid_hw_raw_request() 141 * ``rtype``: the report type (``HID_INPUT_REPORT``, ``HID_FEATURE_REPORT``, 142 * ``HID_OUTPUT_REPORT``) 143 * ``reqtype``: the request 144 * ``source``: a u64 referring to a uniq but identifiable source. If %0, the 145 * kernel itself emitted that call. For hidraw, ``source`` is set 146 * to the associated ``struct file *``. 147 * 148 * Return: %0 to keep processing the request by hid-core; any other value 149 * stops hid-core from processing that event. A positive value should be 150 * returned with the number of bytes returned in the incoming buffer; a 151 * negative error code interrupts the processing of this call. 152 */ 153 int (*hid_hw_request)(struct hid_bpf_ctx *ctx, unsigned char reportnum, 154 enum hid_report_type rtype, enum hid_class_request reqtype, 155 __u64 source); 156 157 /** 158 * @hid_hw_output_report: called whenever a hid_hw_output_report() call is emitted 159 * on the HID device 160 * 161 * It has the following arguments: 162 * 163 * ``ctx``: The HID-BPF context as &struct hid_bpf_ctx 164 * ``source``: a u64 referring to a uniq but identifiable source. If %0, the 165 * kernel itself emitted that call. For hidraw, ``source`` is set 166 * to the associated ``struct file *``. 167 * 168 * Return: %0 to keep processing the request by hid-core; any other value 169 * stops hid-core from processing that event. A positive value should be 170 * returned with the number of bytes written to the device; a negative error 171 * code interrupts the processing of this call. 172 */ 173 int (*hid_hw_output_report)(struct hid_bpf_ctx *ctx, __u64 source); 174 175 176 /* private: do not show up in the docs */ 177 struct hid_device *hdev; 178 }; 179 180 /* stored in each device */ 181 struct hid_bpf { 182 u8 *device_data; /* allocated when a bpf program of type 183 * SEC(f.../hid_bpf_device_event) has been attached 184 * to this HID device 185 */ 186 u32 allocated_data; 187 bool destroyed; /* prevents the assignment of any progs */ 188 189 struct hid_bpf_ops *rdesc_ops; 190 struct list_head prog_list; 191 struct mutex prog_list_lock; /* protects prog_list update */ 192 struct srcu_struct srcu; /* protects prog_list read-only access */ 193 }; 194 195 #ifdef CONFIG_HID_BPF 196 u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data, 197 u32 *size, int interrupt, u64 source); 198 int dispatch_hid_bpf_raw_requests(struct hid_device *hdev, 199 unsigned char reportnum, __u8 *buf, 200 u32 size, enum hid_report_type rtype, 201 enum hid_class_request reqtype, 202 __u64 source, bool from_bpf); 203 int dispatch_hid_bpf_output_report(struct hid_device *hdev, __u8 *buf, u32 size, 204 __u64 source, bool from_bpf); 205 int hid_bpf_connect_device(struct hid_device *hdev); 206 void hid_bpf_disconnect_device(struct hid_device *hdev); 207 void hid_bpf_destroy_device(struct hid_device *hid); 208 int hid_bpf_device_init(struct hid_device *hid); 209 u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size); 210 #else /* CONFIG_HID_BPF */ 211 static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, 212 u8 *data, u32 *size, int interrupt, 213 u64 source) { return data; } 214 static inline int dispatch_hid_bpf_raw_requests(struct hid_device *hdev, 215 unsigned char reportnum, u8 *buf, 216 u32 size, enum hid_report_type rtype, 217 enum hid_class_request reqtype, 218 u64 source, bool from_bpf) { return 0; } 219 static inline int dispatch_hid_bpf_output_report(struct hid_device *hdev, __u8 *buf, u32 size, 220 __u64 source, bool from_bpf) { return 0; } 221 static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; } 222 static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {} 223 static inline void hid_bpf_destroy_device(struct hid_device *hid) {} 224 static inline int hid_bpf_device_init(struct hid_device *hid) { return 0; } 225 #define call_hid_bpf_rdesc_fixup(_hdev, _rdesc, _size) \ 226 ((u8 *)kmemdup(_rdesc, *(_size), GFP_KERNEL)) 227 228 #endif /* CONFIG_HID_BPF */ 229 230 #endif /* __HID_BPF_H */ 231