root/include/linux/bpf.h

INCLUDED FROM

/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 */
#ifndef _LINUX_BPF_H
#define _LINUX_BPF_H 1

#include <uapi/linux/bpf.h>
#include <linux/workqueue.h>
#include <linux/file.h>

struct bpf_map;

/* map is generic key/value storage optionally accesible by eBPF programs */
struct bpf_map_ops {
        /* funcs callable from userspace (via syscall) */
        struct bpf_map *(*map_alloc)(union bpf_attr *attr);
        void (*map_free)(struct bpf_map *);
        int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);

        /* funcs callable from userspace and from eBPF programs */
        void *(*map_lookup_elem)(struct bpf_map *map, void *key);
        int (*map_update_elem)(struct bpf_map *map, void *key, void *value);
        int (*map_delete_elem)(struct bpf_map *map, void *key);
};

struct bpf_map {
        atomic_t refcnt;
        enum bpf_map_type map_type;
        u32 key_size;
        u32 value_size;
        u32 max_entries;
        struct bpf_map_ops *ops;
        struct work_struct work;
};

struct bpf_map_type_list {
        struct list_head list_node;
        struct bpf_map_ops *ops;
        enum bpf_map_type type;
};

void bpf_register_map_type(struct bpf_map_type_list *tl);
void bpf_map_put(struct bpf_map *map);
struct bpf_map *bpf_map_get(struct fd f);

/* function argument constraints */
enum bpf_arg_type {
        ARG_ANYTHING = 0,       /* any argument is ok */

        /* the following constraints used to prototype
         * bpf_map_lookup/update/delete_elem() functions
         */
        ARG_CONST_MAP_PTR,      /* const argument used as pointer to bpf_map */
        ARG_PTR_TO_MAP_KEY,     /* pointer to stack used as map key */
        ARG_PTR_TO_MAP_VALUE,   /* pointer to stack used as map value */

        /* the following constraints used to prototype bpf_memcmp() and other
         * functions that access data on eBPF program stack
         */
        ARG_PTR_TO_STACK,       /* any pointer to eBPF program stack */
        ARG_CONST_STACK_SIZE,   /* number of bytes accessed from stack */
};

/* type of values returned from helper functions */
enum bpf_return_type {
        RET_INTEGER,                    /* function returns integer */
        RET_VOID,                       /* function doesn't return anything */
        RET_PTR_TO_MAP_VALUE_OR_NULL,   /* returns a pointer to map elem value or NULL */
};

/* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
 * to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
 * instructions after verifying
 */
struct bpf_func_proto {
        u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
        bool gpl_only;
        enum bpf_return_type ret_type;
        enum bpf_arg_type arg1_type;
        enum bpf_arg_type arg2_type;
        enum bpf_arg_type arg3_type;
        enum bpf_arg_type arg4_type;
        enum bpf_arg_type arg5_type;
};

/* bpf_context is intentionally undefined structure. Pointer to bpf_context is
 * the first argument to eBPF programs.
 * For socket filters: 'struct bpf_context *' == 'struct sk_buff *'
 */
struct bpf_context;

enum bpf_access_type {
        BPF_READ = 1,
        BPF_WRITE = 2
};

struct bpf_verifier_ops {
        /* return eBPF function prototype for verification */
        const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);

        /* return true if 'size' wide access at offset 'off' within bpf_context
         * with 'type' (read or write) is allowed
         */
        bool (*is_valid_access)(int off, int size, enum bpf_access_type type);
};

struct bpf_prog_type_list {
        struct list_head list_node;
        struct bpf_verifier_ops *ops;
        enum bpf_prog_type type;
};

void bpf_register_prog_type(struct bpf_prog_type_list *tl);

struct bpf_prog;

struct bpf_prog_aux {
        atomic_t refcnt;
        bool is_gpl_compatible;
        enum bpf_prog_type prog_type;
        struct bpf_verifier_ops *ops;
        struct bpf_map **used_maps;
        u32 used_map_cnt;
        struct bpf_prog *prog;
        struct work_struct work;
};

void bpf_prog_put(struct bpf_prog *prog);
struct bpf_prog *bpf_prog_get(u32 ufd);
/* verify correctness of eBPF program */
int bpf_check(struct bpf_prog *fp, union bpf_attr *attr);

#endif /* _LINUX_BPF_H */