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Diffstat (limited to 'include/linux/hid_bpf.h')
| -rw-r--r-- | include/linux/hid_bpf.h | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/include/linux/hid_bpf.h b/include/linux/hid_bpf.h new file mode 100644 index 000000000000..a2e47dbcf82c --- /dev/null +++ b/include/linux/hid_bpf.h @@ -0,0 +1,236 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ + +#ifndef __HID_BPF_H +#define __HID_BPF_H + +#include <linux/bpf.h> +#include <linux/mutex.h> +#include <linux/srcu.h> +#include <uapi/linux/hid.h> + +struct hid_device; + +/* + * The following is the user facing HID BPF API. + * + * Extra care should be taken when editing this part, as + * it might break existing out of the tree bpf programs. + */ + +/** + * struct hid_bpf_ctx - User accessible data for all HID programs + * + * ``data`` is not directly accessible from the context. We need to issue + * a call to hid_bpf_get_data() in order to get a pointer to that field. + * + * @hid: the &struct hid_device representing the device itself + * @allocated_size: Allocated size of data. + * + * This is how much memory is available and can be requested + * by the HID program. + * Note that for ``HID_BPF_RDESC_FIXUP``, that memory is set to + * ``4096`` (4 KB) + * @size: Valid data in the data field. + * + * Programs can get the available valid size in data by fetching this field. + * Programs can also change this value by returning a positive number in the + * program. + * To discard the event, return a negative error code. + * + * ``size`` must always be less or equal than ``allocated_size`` (it is enforced + * once all BPF programs have been run). + * @retval: Return value of the previous program. + * + * ``hid`` and ``allocated_size`` are read-only, ``size`` and ``retval`` are read-write. + */ +struct hid_bpf_ctx { + struct hid_device *hid; + __u32 allocated_size; + union { + __s32 retval; + __s32 size; + }; +}; + +/* + * Below is HID internal + */ + +#define HID_BPF_MAX_PROGS_PER_DEV 64 +#define HID_BPF_FLAG_MASK (((HID_BPF_FLAG_MAX - 1) << 1) - 1) + + +struct hid_report_enum; + +struct hid_ops { + struct hid_report *(*hid_get_report)(struct hid_report_enum *report_enum, const u8 *data); + int (*hid_hw_raw_request)(struct hid_device *hdev, + unsigned char reportnum, __u8 *buf, + size_t len, enum hid_report_type rtype, + enum hid_class_request reqtype, + u64 source, bool from_bpf); + int (*hid_hw_output_report)(struct hid_device *hdev, __u8 *buf, size_t len, + u64 source, bool from_bpf); + int (*hid_input_report)(struct hid_device *hid, enum hid_report_type type, + u8 *data, u32 size, int interrupt, u64 source, bool from_bpf, + bool lock_already_taken); + struct module *owner; + const struct bus_type *bus_type; +}; + +extern const struct hid_ops *hid_ops; + +/** + * struct hid_bpf_ops - A BPF struct_ops of callbacks allowing to attach HID-BPF + * programs to a HID device + * @hid_id: the HID uniq ID to attach to. This is writeable before ``load()``, and + * cannot be changed after + * @flags: flags used while attaching the struct_ops to the device. Currently only + * available value is %0 or ``BPF_F_BEFORE``. + * Writeable only before ``load()`` + */ +struct hid_bpf_ops { + /* hid_id needs to stay first so we can easily change it + * from userspace. + */ + int hid_id; + u32 flags; + + /* private: do not show up in the docs */ + struct list_head list; + + /* public: rest should show up in the docs */ + + /** + * @hid_device_event: called whenever an event is coming in from the device + * + * It has the following arguments: + * + * ``ctx``: The HID-BPF context as &struct hid_bpf_ctx + * + * Return: %0 on success and keep processing; a positive + * value to change the incoming size buffer; a negative + * error code to interrupt the processing of this event + * + * Context: Interrupt context. + */ + int (*hid_device_event)(struct hid_bpf_ctx *ctx, enum hid_report_type report_type, + u64 source); + + /** + * @hid_rdesc_fixup: called when the probe function parses the report descriptor + * of the HID device + * + * It has the following arguments: + * + * ``ctx``: The HID-BPF context as &struct hid_bpf_ctx + * + * Return: %0 on success and keep processing; a positive + * value to change the incoming size buffer; a negative + * error code to interrupt the processing of this device + */ + int (*hid_rdesc_fixup)(struct hid_bpf_ctx *ctx); + + /** + * @hid_hw_request: called whenever a hid_hw_raw_request() call is emitted + * on the HID device + * + * It has the following arguments: + * + * ``ctx``: The HID-BPF context as &struct hid_bpf_ctx + * + * ``reportnum``: the report number, as in hid_hw_raw_request() + * + * ``rtype``: the report type (``HID_INPUT_REPORT``, ``HID_FEATURE_REPORT``, + * ``HID_OUTPUT_REPORT``) + * + * ``reqtype``: the request + * + * ``source``: a u64 referring to a uniq but identifiable source. If %0, the + * kernel itself emitted that call. For hidraw, ``source`` is set + * to the associated ``struct file *``. + * + * Return: %0 to keep processing the request by hid-core; any other value + * stops hid-core from processing that event. A positive value should be + * returned with the number of bytes returned in the incoming buffer; a + * negative error code interrupts the processing of this call. + */ + int (*hid_hw_request)(struct hid_bpf_ctx *ctx, unsigned char reportnum, + enum hid_report_type rtype, enum hid_class_request reqtype, + u64 source); + + /** + * @hid_hw_output_report: called whenever a hid_hw_output_report() call is emitted + * on the HID device + * + * It has the following arguments: + * + * ``ctx``: The HID-BPF context as &struct hid_bpf_ctx + * + * ``source``: a u64 referring to a uniq but identifiable source. If %0, the + * kernel itself emitted that call. For hidraw, ``source`` is set + * to the associated ``struct file *``. + * + * Return: %0 to keep processing the request by hid-core; any other value + * stops hid-core from processing that event. A positive value should be + * returned with the number of bytes written to the device; a negative error + * code interrupts the processing of this call. + */ + int (*hid_hw_output_report)(struct hid_bpf_ctx *ctx, u64 source); + + + /* private: do not show up in the docs */ + struct hid_device *hdev; +}; + +/* stored in each device */ +struct hid_bpf { + u8 *device_data; /* allocated when a bpf program of type + * SEC(f.../hid_bpf_device_event) has been attached + * to this HID device + */ + u32 allocated_data; + bool destroyed; /* prevents the assignment of any progs */ + + struct hid_bpf_ops *rdesc_ops; + struct list_head prog_list; + struct mutex prog_list_lock; /* protects prog_list update */ + struct srcu_struct srcu; /* protects prog_list read-only access */ +}; + +#ifdef CONFIG_HID_BPF +u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data, + u32 *size, int interrupt, u64 source, bool from_bpf); +int dispatch_hid_bpf_raw_requests(struct hid_device *hdev, + unsigned char reportnum, __u8 *buf, + u32 size, enum hid_report_type rtype, + enum hid_class_request reqtype, + u64 source, bool from_bpf); +int dispatch_hid_bpf_output_report(struct hid_device *hdev, __u8 *buf, u32 size, + u64 source, bool from_bpf); +int hid_bpf_connect_device(struct hid_device *hdev); +void hid_bpf_disconnect_device(struct hid_device *hdev); +void hid_bpf_destroy_device(struct hid_device *hid); +int hid_bpf_device_init(struct hid_device *hid); +const u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, const u8 *rdesc, unsigned int *size); +#else /* CONFIG_HID_BPF */ +static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, + u8 *data, u32 *size, int interrupt, + u64 source, bool from_bpf) { return data; } +static inline int dispatch_hid_bpf_raw_requests(struct hid_device *hdev, + unsigned char reportnum, u8 *buf, + u32 size, enum hid_report_type rtype, + enum hid_class_request reqtype, + u64 source, bool from_bpf) { return 0; } +static inline int dispatch_hid_bpf_output_report(struct hid_device *hdev, __u8 *buf, u32 size, + u64 source, bool from_bpf) { return 0; } +static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; } +static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {} +static inline void hid_bpf_destroy_device(struct hid_device *hid) {} +static inline int hid_bpf_device_init(struct hid_device *hid) { return 0; } +static inline const u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, const u8 *rdesc, + unsigned int *size) { return rdesc; } + +#endif /* CONFIG_HID_BPF */ + +#endif /* __HID_BPF_H */ |