include/linux/bpf.h

   1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   2  *
   3  * This program is free software; you can redistribute it and/or
   4  * modify it under the terms of version 2 of the GNU General Public
   5  * License as published by the Free Software Foundation.
   6  */
   7 #ifndef _LINUX_BPF_H
   8 #define _LINUX_BPF_H 1
   9
  10 #include <uapi/linux/bpf.h>
  11 #include <linux/workqueue.h>
  12 #include <linux/file.h>
  13
  14 struct bpf_map;
  15
  16 /* map is generic key/value storage optionally accesible by eBPF programs */
  17 struct bpf_map_ops {
  18         /* funcs callable from userspace (via syscall) */
  19         struct bpf_map *(*map_alloc)(union bpf_attr *attr);
  20         void (*map_free)(struct bpf_map *);
  21         int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
  22
  23         /* funcs callable from userspace and from eBPF programs */
  24         void *(*map_lookup_elem)(struct bpf_map *map, void *key);
  25         int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
  26         int (*map_delete_elem)(struct bpf_map *map, void *key);
  27 };
  28
  29 struct bpf_map {
  30         atomic_t refcnt;
  31         enum bpf_map_type map_type;
  32         u32 key_size;
  33         u32 value_size;
  34         u32 max_entries;
  35         const struct bpf_map_ops *ops;
  36         struct work_struct work;
  37 };
  38
  39 struct bpf_map_type_list {
  40         struct list_head list_node;
  41         const struct bpf_map_ops *ops;
  42         enum bpf_map_type type;
  43 };
  44
  45 /* function argument constraints */
  46 enum bpf_arg_type {
  47         ARG_ANYTHING = 0,       /* any argument is ok */
  48
  49         /* the following constraints used to prototype
  50          * bpf_map_lookup/update/delete_elem() functions
  51          */
  52         ARG_CONST_MAP_PTR,      /* const argument used as pointer to bpf_map */
  53         ARG_PTR_TO_MAP_KEY,     /* pointer to stack used as map key */
  54         ARG_PTR_TO_MAP_VALUE,   /* pointer to stack used as map value */
  55
  56         /* the following constraints used to prototype bpf_memcmp() and other
  57          * functions that access data on eBPF program stack
  58          */
  59         ARG_PTR_TO_STACK,       /* any pointer to eBPF program stack */
  60         ARG_CONST_STACK_SIZE,   /* number of bytes accessed from stack */
  61 };
  62
  63 /* type of values returned from helper functions */
  64 enum bpf_return_type {
  65         RET_INTEGER,                    /* function returns integer */
  66         RET_VOID,                       /* function doesn't return anything */
  67         RET_PTR_TO_MAP_VALUE_OR_NULL,   /* returns a pointer to map elem value or NULL */
  68 };
  69
  70 /* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
  71  * to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
  72  * instructions after verifying
  73  */
  74 struct bpf_func_proto {
  75         u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
  76         bool gpl_only;
  77         enum bpf_return_type ret_type;
  78         enum bpf_arg_type arg1_type;
  79         enum bpf_arg_type arg2_type;
  80         enum bpf_arg_type arg3_type;
  81         enum bpf_arg_type arg4_type;
  82         enum bpf_arg_type arg5_type;
  83 };
  84
  85 /* bpf_context is intentionally undefined structure. Pointer to bpf_context is
  86  * the first argument to eBPF programs.
  87  * For socket filters: 'struct bpf_context *' == 'struct sk_buff *'
  88  */
  89 struct bpf_context;
  90
  91 enum bpf_access_type {
  92         BPF_READ = 1,
  93         BPF_WRITE = 2
  94 };
  95
  96 struct bpf_verifier_ops {
  97         /* return eBPF function prototype for verification */
  98         const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);
  99
 100         /* return true if 'size' wide access at offset 'off' within bpf_context
 101          * with 'type' (read or write) is allowed
 102          */
 103         bool (*is_valid_access)(int off, int size, enum bpf_access_type type);
 104 };
 105
 106 struct bpf_prog_type_list {
 107         struct list_head list_node;
 108         const struct bpf_verifier_ops *ops;
 109         enum bpf_prog_type type;
 110 };
 111
 112 struct bpf_prog;
 113
 114 struct bpf_prog_aux {
 115         atomic_t refcnt;
 116         u32 used_map_cnt;
 117         const struct bpf_verifier_ops *ops;
 118         struct bpf_map **used_maps;
 119         struct bpf_prog *prog;
 120         struct work_struct work;
 121 };
 122
 123 #ifdef CONFIG_BPF_SYSCALL
 124 void bpf_register_prog_type(struct bpf_prog_type_list *tl);
 125 void bpf_register_map_type(struct bpf_map_type_list *tl);
 126
 127 struct bpf_prog *bpf_prog_get(u32 ufd);
 128 void bpf_prog_put(struct bpf_prog *prog);
 129
 130 struct bpf_map *bpf_map_get(struct fd f);
 131 void bpf_map_put(struct bpf_map *map);
 132
 133 /* verify correctness of eBPF program */
 134 int bpf_check(struct bpf_prog *fp, union bpf_attr *attr);
 135 #else
 136 static inline void bpf_register_prog_type(struct bpf_prog_type_list *tl)
 137 {
 138 }
 139
 140 static inline struct bpf_prog *bpf_prog_get(u32 ufd)
 141 {
 142         return ERR_PTR(-EOPNOTSUPP);
 143 }
 144
 145 static inline void bpf_prog_put(struct bpf_prog *prog)
 146 {
 147 }
 148 #endif /* CONFIG_BPF_SYSCALL */
 149
 150 /* verifier prototypes for helper functions called from eBPF programs */
 151 extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
 152 extern const struct bpf_func_proto bpf_map_update_elem_proto;
 153 extern const struct bpf_func_proto bpf_map_delete_elem_proto;
 154
 155 #endif /* _LINUX_BPF_H */