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 int target_hid = 0;
31 bool is_cgroup1 = 0;
32
33 struct cgroup *bpf_task_get_cgroup1(struct task_struct *task, int hierarchy_id) __ksym;
34 void bpf_cgroup_release(struct cgroup *cgrp) __ksym;
35
36 static void __on_enter(struct pt_regs *regs, long id, struct cgroup *cgrp)
37 {
38 long *ptr;
39 int err;
40
41 /* populate value 0 */
42 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
43 BPF_LOCAL_STORAGE_GET_F_CREATE);
44 if (!ptr)
45 return;
46
47 /* delete value 0 */
48 err = bpf_cgrp_storage_delete(&map_a, cgrp);
49 if (err)
50 return;
51
52 /* value is not available */
53 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, 0);
54 if (ptr)
55 return;
56
57 /* re-populate the value */
58 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
59 BPF_LOCAL_STORAGE_GET_F_CREATE);
60 if (!ptr)
61 return;
62 __sync_fetch_and_add(&enter_cnt, 1);
63 *ptr = MAGIC_VALUE + enter_cnt;
64 }
65
66 SEC("tp_btf/sys_enter")
67 int BPF_PROG(on_enter, struct pt_regs *regs, long id)
68 {
69 struct task_struct *task;
70 struct cgroup *cgrp;
71
72 task = bpf_get_current_task_btf();
73 if (task->pid != target_pid)
74 return 0;
75
76 if (is_cgroup1) {
77 cgrp = bpf_task_get_cgroup1(task, target_hid);
78 if (!cgrp)
79 return 0;
80
81 __on_enter(regs, id, cgrp);
82 bpf_cgroup_release(cgrp);
83 return 0;
84 }
85
86 __on_enter(regs, id, task->cgroups->dfl_cgrp);
87 return 0;
88 }
89
90 static void __on_exit(struct pt_regs *regs, long id, struct cgroup *cgrp)
91 {
92 long *ptr;
93
94 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
95 BPF_LOCAL_STORAGE_GET_F_CREATE);
96 if (!ptr)
97 return;
98
99 __sync_fetch_and_add(&exit_cnt, 1);
100 if (*ptr != MAGIC_VALUE + exit_cnt)
101 __sync_fetch_and_add(&mismatch_cnt, 1);
102 }
103
104 SEC("tp_btf/sys_exit")
105 int BPF_PROG(on_exit, struct pt_regs *regs, long id)
106 {
107 struct task_struct *task;
108 struct cgroup *cgrp;
109
110 task = bpf_get_current_task_btf();
111 if (task->pid != target_pid)
112 return 0;
113
114 if (is_cgroup1) {
115 cgrp = bpf_task_get_cgroup1(task, target_hid);
116 if (!cgrp)
117 return 0;
118
119 __on_exit(regs, id, cgrp);
120 bpf_cgroup_release(cgrp);
121 return 0;
122 }
123
124 __on_exit(regs, id, task->cgroups->dfl_cgrp);
125 return 0;
126 }
127
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