LXR linux/include/linux/bpf

   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_VERIFIER_H
   8#define _LINUX_BPF_VERIFIER_H 1
   9
  10#include <linux/bpf.h> /* for enum bpf_reg_type */
  11#include <linux/filter.h> /* for MAX_BPF_STACK */
  12
  13 /* Just some arbitrary values so we can safely do math without overflowing and
  14  * are obviously wrong for any sort of memory access.
  15  */
  16#define BPF_REGISTER_MAX_RANGE (1024 * 1024 * 1024)
  17#define BPF_REGISTER_MIN_RANGE -1
  18
  19struct bpf_reg_state {
  20        enum bpf_reg_type type;
  21        /*
  22         * Used to determine if any memory access using this register will
  23         * result in a bad access.
  24         */
  25        s64 min_value;
  26        u64 max_value;
  27        union {
  28                /* valid when type == CONST_IMM | PTR_TO_STACK | UNKNOWN_VALUE */
  29                s64 imm;
  30
  31                /* valid when type == PTR_TO_PACKET* */
  32                struct {
  33                        u32 id;
  34                        u16 off;
  35                        u16 range;
  36                };
  37
  38                /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |
  39                 *   PTR_TO_MAP_VALUE_OR_NULL
  40                 */
  41                struct bpf_map *map_ptr;
  42        };
  43};
  44
  45enum bpf_stack_slot_type {
  46        STACK_INVALID,    /* nothing was stored in this stack slot */
  47        STACK_SPILL,      /* register spilled into stack */
  48        STACK_MISC        /* BPF program wrote some data into this slot */
  49};
  50
  51#define BPF_REG_SIZE 8  /* size of eBPF register in bytes */
  52
  53/* state of the program:
  54 * type of all registers and stack info
  55 */
  56struct bpf_verifier_state {
  57        struct bpf_reg_state regs[MAX_BPF_REG];
  58        u8 stack_slot_type[MAX_BPF_STACK];
  59        struct bpf_reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE];
  60};
  61
  62/* linked list of verifier states used to prune search */
  63struct bpf_verifier_state_list {
  64        struct bpf_verifier_state state;
  65        struct bpf_verifier_state_list *next;
  66};
  67
  68struct bpf_insn_aux_data {
  69        enum bpf_reg_type ptr_type;     /* pointer type for load/store insns */
  70};
  71
  72#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
  73
  74struct bpf_verifier_env;
  75struct bpf_ext_analyzer_ops {
  76        int (*insn_hook)(struct bpf_verifier_env *env,
  77                         int insn_idx, int prev_insn_idx);
  78};
  79
  80/* single container for all structs
  81 * one verifier_env per bpf_check() call
  82 */
  83struct bpf_verifier_env {
  84        struct bpf_prog *prog;          /* eBPF program being verified */
  85        struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */
  86        int stack_size;                 /* number of states to be processed */
  87        struct bpf_verifier_state cur_state; /* current verifier state */
  88        struct bpf_verifier_state_list **explored_states; /* search pruning optimization */
  89        const struct bpf_ext_analyzer_ops *analyzer_ops; /* external analyzer ops */
  90        void *analyzer_priv; /* pointer to external analyzer's private data */
  91        struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
  92        u32 used_map_cnt;               /* number of used maps */
  93        u32 id_gen;                     /* used to generate unique reg IDs */
  94        bool allow_ptr_leaks;
  95        bool seen_direct_write;
  96        bool varlen_map_value_access;
  97        struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
  98};
  99
 100int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
 101                 void *priv);
 102
 103#endif /* _LINUX_BPF_VERIFIER_H */
 104