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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 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
49enum 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 */
60struct 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 */
67struct bpf_verifier_state_list {
68 struct bpf_verifier_state state;
69 struct bpf_verifier_state_list *next;
70};
71
72struct 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
83struct bpf_verifier_env;
84struct 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 */
92struct 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
110int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
111 void *priv);
112
113#endif /* _LINUX_BPF_VERIFIER_H */