Line data    Source code

       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             : 
      10             : struct 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             :  */
      49             : struct 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             :  */
      70             : enum 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 */
      77             : int hid_bpf_device_event(struct hid_bpf_ctx *ctx);
      78             : int 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 */
      85             : int hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags);
      86             : int 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);
      88             : struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id);
      89             : void 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 */
      96             : int __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 */
     102             : enum 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             : 
     109             : struct hid_report_enum;
     110             : 
     111             : struct 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             : 
     121             : extern struct hid_bpf_ops *hid_bpf_ops;
     122             : 
     123             : struct 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 */
     129             : struct 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 */
     143             : struct hid_bpf_link {
     144             :         struct bpf_link link;
     145             :         int hid_table_index;
     146             : };
     147             : 
     148             : #ifdef CONFIG_HID_BPF
     149             : u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data,
     150             :                                   u32 *size, int interrupt);
     151             : int hid_bpf_connect_device(struct hid_device *hdev);
     152             : void hid_bpf_disconnect_device(struct hid_device *hdev);
     153             : void hid_bpf_destroy_device(struct hid_device *hid);
     154             : void hid_bpf_device_init(struct hid_device *hid);
     155             : u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size);
     156             : #else /* CONFIG_HID_BPF */
     157             : static 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; }
     159             : static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; }
     160             : static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {}
     161             : static inline void hid_bpf_destroy_device(struct hid_device *hid) {}
     162             : static inline void hid_bpf_device_init(struct hid_device *hid) {}
     163             : static inline u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size)
     164             : {
     165           0 :         return kmemdup(rdesc, *size, GFP_KERNEL);
     166             : }
     167             : 
     168             : #endif /* CONFIG_HID_BPF */
     169             : 
     170             : #endif /* __HID_BPF_H */