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_DONTCARE = 0,       /* unused argument in helper function */
  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         ARG_PTR_TO_CTX,         /* pointer to context */
  63         ARG_ANYTHING,           /* any (initialized) argument is ok */
  64 };
  65
  66 /* type of values returned from helper functions */
  67 enum bpf_return_type {
  68         RET_INTEGER,                    /* function returns integer */
  69         RET_VOID,                       /* function doesn't return anything */
  70         RET_PTR_TO_MAP_VALUE_OR_NULL,   /* returns a pointer to map elem value or NULL */
  71 };
  72
  73 /* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
  74  * to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
  75  * instructions after verifying
  76  */
  77 struct bpf_func_proto {
  78         u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
  79         bool gpl_only;
  80         enum bpf_return_type ret_type;
  81         enum bpf_arg_type arg1_type;
  82         enum bpf_arg_type arg2_type;
  83         enum bpf_arg_type arg3_type;
  84         enum bpf_arg_type arg4_type;
  85         enum bpf_arg_type arg5_type;
  86 };
  87
  88 /* bpf_context is intentionally undefined structure. Pointer to bpf_context is
  89  * the first argument to eBPF programs.
  90  * For socket filters: 'struct bpf_context *' == 'struct sk_buff *'
  91  */
  92 struct bpf_context;
  93
  94 enum bpf_access_type {
  95         BPF_READ = 1,
  96         BPF_WRITE = 2
  97 };
  98
  99 struct bpf_verifier_ops {
 100         /* return eBPF function prototype for verification */
 101         const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);
 102
 103         /* return true if 'size' wide access at offset 'off' within bpf_context
 104          * with 'type' (read or write) is allowed
 105          */
 106         bool (*is_valid_access)(int off, int size, enum bpf_access_type type);
 107
 108         u32 (*convert_ctx_access)(int dst_reg, int src_reg, int ctx_off,
 109                                   struct bpf_insn *insn);
 110 };
 111
 112 struct bpf_prog_type_list {
 113         struct list_head list_node;
 114         const struct bpf_verifier_ops *ops;
 115         enum bpf_prog_type type;
 116 };
 117
 118 struct bpf_prog;
 119
 120 struct bpf_prog_aux {
 121         atomic_t refcnt;
 122         u32 used_map_cnt;
 123         const struct bpf_verifier_ops *ops;
 124         struct bpf_map **used_maps;
 125         struct bpf_prog *prog;
 126         struct work_struct work;
 127 };
 128
 129 #ifdef CONFIG_BPF_SYSCALL
 130 void bpf_register_prog_type(struct bpf_prog_type_list *tl);
 131 void bpf_register_map_type(struct bpf_map_type_list *tl);
 132
 133 struct bpf_prog *bpf_prog_get(u32 ufd);
 134 void bpf_prog_put(struct bpf_prog *prog);
 135
 136 struct bpf_map *bpf_map_get(struct fd f);
 137 void bpf_map_put(struct bpf_map *map);
 138
 139 /* verify correctness of eBPF program */
 140 int bpf_check(struct bpf_prog **fp, union bpf_attr *attr);
 141 #else
 142 static inline void bpf_register_prog_type(struct bpf_prog_type_list *tl)
 143 {
 144 }
 145
 146 static inline struct bpf_prog *bpf_prog_get(u32 ufd)
 147 {
 148         return ERR_PTR(-EOPNOTSUPP);
 149 }
 150
 151 static inline void bpf_prog_put(struct bpf_prog *prog)
 152 {
 153 }
 154 #endif /* CONFIG_BPF_SYSCALL */
 155
 156 /* verifier prototypes for helper functions called from eBPF programs */
 157 extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
 158 extern const struct bpf_func_proto bpf_map_update_elem_proto;
 159 extern const struct bpf_func_proto bpf_map_delete_elem_proto;
 160
 161 extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
 162 extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
 163
 164 #endif /* _LINUX_BPF_H */