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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};
47
48enum bpf_stack_slot_type {
49 STACK_INVALID, /* nothing was stored in this stack slot */
50 STACK_SPILL, /* register spilled into stack */
51 STACK_MISC /* BPF program wrote some data into this slot */
52};
53
54#define BPF_REG_SIZE 8 /* size of eBPF register in bytes */
55
56/* state of the program:
57 * type of all registers and stack info
58 */
59struct bpf_verifier_state {
60 struct bpf_reg_state regs[MAX_BPF_REG];
61 u8 stack_slot_type[MAX_BPF_STACK];
62 struct bpf_reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE];
63};
64
65/* linked list of verifier states used to prune search */
66struct bpf_verifier_state_list {
67 struct bpf_verifier_state state;
68 struct bpf_verifier_state_list *next;
69};
70
71struct bpf_insn_aux_data {
72 union {
73 enum bpf_reg_type ptr_type; /* pointer type for load/store insns */
74 struct bpf_map *map_ptr; /* pointer for call insn into lookup_elem */
75 };
76};
77
78#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
79
80struct bpf_verifier_env;
81struct bpf_ext_analyzer_ops {
82 int (*insn_hook)(struct bpf_verifier_env *env,
83 int insn_idx, int prev_insn_idx);
84};
85
86/* single container for all structs
87 * one verifier_env per bpf_check() call
88 */
89struct bpf_verifier_env {
90 struct bpf_prog *prog; /* eBPF program being verified */
91 struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */
92 int stack_size; /* number of states to be processed */
93 bool strict_alignment; /* perform strict pointer alignment checks */
94 struct bpf_verifier_state cur_state; /* current verifier state */
95 struct bpf_verifier_state_list **explored_states; /* search pruning optimization */
96 const struct bpf_ext_analyzer_ops *analyzer_ops; /* external analyzer ops */
97 void *analyzer_priv; /* pointer to external analyzer's private data */
98 struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
99 u32 used_map_cnt; /* number of used maps */
100 u32 id_gen; /* used to generate unique reg IDs */
101 bool allow_ptr_leaks;
102 bool seen_direct_write;
103 bool varlen_map_value_access;
104 struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
105};
106
107int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
108 void *priv);
109
110#endif /* _LINUX_BPF_VERIFIER_H */