include/linux/bpf_verifier.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_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
  19 struct bpf_reg_state {
  20         enum bpf_reg_type type;
  21         union {
  22                 /* valid when type == CONST_IMM | PTR_TO_STACK | UNKNOWN_VALUE */
  23                 s64 imm;
  24
  25                 /* valid when type == PTR_TO_PACKET* */
  26                 struct {
  27                         u16 off;
  28                         u16 range;
  29                 };
  30
  31                 /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |
  32                  *   PTR_TO_MAP_VALUE_OR_NULL
  33                  */
  34                 struct bpf_map *map_ptr;
  35         };
  36         u32 id;
  37         /* Used to determine if any memory access using this register will
  38          * result in a bad access. These two fields must be last.
  39          * See states_equal()
  40          */
  41         s64 min_value;
  42         u64 max_value;
  43         u32 min_align;
  44         u32 aux_off;
  45         u32 aux_off_align;
  46         bool value_from_signed;
  47 };
  48
  49 enum bpf_stack_slot_type {
  50         STACK_INVALID,    /* nothing was stored in this stack slot */
  51         STACK_SPILL,      /* register spilled into stack */
  52         STACK_MISC        /* BPF program wrote some data into this slot */
  53 };
  54
  55 #define BPF_REG_SIZE 8  /* size of eBPF register in bytes */
  56
  57 /* state of the program:
  58  * type of all registers and stack info
  59  */
  60 struct bpf_verifier_state {
  61         struct bpf_reg_state regs[MAX_BPF_REG];
  62         u8 stack_slot_type[MAX_BPF_STACK];
  63         struct bpf_reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE];
  64 };
  65
  66 /* linked list of verifier states used to prune search */
  67 struct bpf_verifier_state_list {
  68         struct bpf_verifier_state state;
  69         struct bpf_verifier_state_list *next;
  70 };
  71
  72 struct bpf_insn_aux_data {
  73         union {
  74                 enum bpf_reg_type ptr_type;     /* pointer type for load/store insns */
  75                 struct bpf_map *map_ptr;        /* pointer for call insn into lookup_elem */
  76         };
  77         int ctx_field_size; /* the ctx field size for load insn, maybe 0 */
  78         int converted_op_size; /* the valid value width after perceived conversion */
  79 };
  80
  81 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
  82
  83 struct bpf_verifier_env;
  84 struct bpf_ext_analyzer_ops {
  85         int (*insn_hook)(struct bpf_verifier_env *env,
  86                          int insn_idx, int prev_insn_idx);
  87 };
  88
  89 /* single container for all structs
  90  * one verifier_env per bpf_check() call
  91  */
  92 struct bpf_verifier_env {
  93         struct bpf_prog *prog;          /* eBPF program being verified */
  94         struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */
  95         int stack_size;                 /* number of states to be processed */
  96         bool strict_alignment;          /* perform strict pointer alignment checks */
  97         struct bpf_verifier_state cur_state; /* current verifier state */
  98         struct bpf_verifier_state_list **explored_states; /* search pruning optimization */
  99         const struct bpf_ext_analyzer_ops *analyzer_ops; /* external analyzer ops */
 100         void *analyzer_priv; /* pointer to external analyzer's private data */
 101         struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
 102         u32 used_map_cnt;               /* number of used maps */
 103         u32 id_gen;                     /* used to generate unique reg IDs */
 104         bool allow_ptr_leaks;
 105         bool seen_direct_write;
 106         bool varlen_map_value_access;
 107         struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
 108 };
 109
 110 int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
 111                  void *priv);
 112
 113 #endif /* _LINUX_BPF_VERIFIER_H */