1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
3 
4 #include "vmlinux.h"
5 #include <bpf/bpf_helpers.h>
6 #include <bpf/bpf_tracing.h>
7 
8 char _license[] SEC("license") = "GPL";
9 
10 struct {
11 	__uint(type, BPF_MAP_TYPE_CGRP_STORAGE);
12 	__uint(map_flags, BPF_F_NO_PREALLOC);
13 	__type(key, int);
14 	__type(value, long);
15 } map_a SEC(".maps");
16 
17 struct {
18 	__uint(type, BPF_MAP_TYPE_CGRP_STORAGE);
19 	__uint(map_flags, BPF_F_NO_PREALLOC);
20 	__type(key, int);
21 	__type(value, long);
22 } map_b SEC(".maps");
23 
24 #define MAGIC_VALUE 0xabcd1234
25 
26 pid_t target_pid = 0;
27 int mismatch_cnt = 0;
28 int enter_cnt = 0;
29 int exit_cnt = 0;
30 
31 SEC("tp_btf/sys_enter")
32 int BPF_PROG(on_enter, struct pt_regs *regs, long id)
33 {
34 	struct task_struct *task;
35 	long *ptr;
36 	int err;
37 
38 	task = bpf_get_current_task_btf();
39 	if (task->pid != target_pid)
40 		return 0;
41 
42 	/* populate value 0 */
43 	ptr = bpf_cgrp_storage_get(&map_a, task->cgroups->dfl_cgrp, 0,
44 				   BPF_LOCAL_STORAGE_GET_F_CREATE);
45 	if (!ptr)
46 		return 0;
47 
48 	/* delete value 0 */
49 	err = bpf_cgrp_storage_delete(&map_a, task->cgroups->dfl_cgrp);
50 	if (err)
51 		return 0;
52 
53 	/* value is not available */
54 	ptr = bpf_cgrp_storage_get(&map_a, task->cgroups->dfl_cgrp, 0, 0);
55 	if (ptr)
56 		return 0;
57 
58 	/* re-populate the value */
59 	ptr = bpf_cgrp_storage_get(&map_a, task->cgroups->dfl_cgrp, 0,
60 				   BPF_LOCAL_STORAGE_GET_F_CREATE);
61 	if (!ptr)
62 		return 0;
63 	__sync_fetch_and_add(&enter_cnt, 1);
64 	*ptr = MAGIC_VALUE + enter_cnt;
65 
66 	return 0;
67 }
68 
69 SEC("tp_btf/sys_exit")
70 int BPF_PROG(on_exit, struct pt_regs *regs, long id)
71 {
72 	struct task_struct *task;
73 	long *ptr;
74 
75 	task = bpf_get_current_task_btf();
76 	if (task->pid != target_pid)
77 		return 0;
78 
79 	ptr = bpf_cgrp_storage_get(&map_a, task->cgroups->dfl_cgrp, 0,
80 				   BPF_LOCAL_STORAGE_GET_F_CREATE);
81 	if (!ptr)
82 		return 0;
83 
84 	__sync_fetch_and_add(&exit_cnt, 1);
85 	if (*ptr != MAGIC_VALUE + exit_cnt)
86 		__sync_fetch_and_add(&mismatch_cnt, 1);
87 	return 0;
88 }
89