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_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_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_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_map: &outer_htab_map); |
93 | } |
94 | |