1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2023. Huawei Technologies Co., Ltd */
3 #include <linux/bpf.h>
4 #include <time.h>
5 #include <bpf/bpf_helpers.h>
6
7 #include "bpf_misc.h"
8
9 struct inner_map_type {
10 __uint(type, BPF_MAP_TYPE_ARRAY);
11 __uint(key_size, 4);
12 __uint(value_size, 4);
13 __uint(max_entries, 1);
14 } inner_map SEC(".maps");
15
16 struct {
17 __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
18 __type(key, int);
19 __type(value, int);
20 __uint(max_entries, 1);
21 __array(values, struct inner_map_type);
22 } outer_array_map SEC(".maps") = {
23 .values = {
24 [0] = &inner_map,
25 },
26 };
27
28 struct {
29 __uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
30 __type(key, int);
31 __type(value, int);
32 __uint(max_entries, 1);
33 __array(values, struct inner_map_type);
34 } outer_htab_map SEC(".maps") = {
35 .values = {
36 [0] = &inner_map,
37 },
38 };
39
40 char _license[] SEC("license") = "GPL";
41
42 int tgid = 0;
43
44 static int acc_map_in_map(void *outer_map)
45 {
46 int i, key, value = 0xdeadbeef;
47 void *inner_map;
48
49 if ((bpf_get_current_pid_tgid() >> 32) != tgid)
50 return 0;
51
52 /* Find nonexistent inner map */
53 key = 1;
54 inner_map = bpf_map_lookup_elem(outer_map, &key);
55 if (inner_map)
56 return 0;
57
58 /* Find the old inner map */
59 key = 0;
60 inner_map = bpf_map_lookup_elem(outer_map, &key);
61 if (!inner_map)
62 return 0;
63
64 /* Wait for the old inner map to be replaced */
65 for (i = 0; i < 2048; i++)
66 bpf_map_update_elem(inner_map, &key, &value, 0);
67
68 return 0;
69 }
70
71 SEC("?kprobe/" SYS_PREFIX "sys_getpgid")
72 int access_map_in_array(void *ctx)
73 {
74 return acc_map_in_map(&outer_array_map);
75 }
76
77 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
78 int sleepable_access_map_in_array(void *ctx)
79 {
80 return acc_map_in_map(&outer_array_map);
81 }
82
83 SEC("?kprobe/" SYS_PREFIX "sys_getpgid")
84 int access_map_in_htab(void *ctx)
85 {
86 return acc_map_in_map(&outer_htab_map);
87 }
88
89 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
90 int sleepable_access_map_in_htab(void *ctx)
91 {
92 return acc_map_in_map(&outer_htab_map);
93 }
94
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.