1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2020 Facebook
3#include <linux/bpf.h>
4#include <bpf/bpf_helpers.h>
5#include <bpf/bpf_core_read.h>
6
7struct task_struct {
8	int tgid;
9} __attribute__((preserve_access_index));
10
11struct {
12	__uint(type, BPF_MAP_TYPE_ARRAY);
13	__uint(max_entries, 1);
14	__type(key, int);
15	__type(value, int);
16} exp_tgid_map SEC(".maps");
17
18struct {
19	__uint(type, BPF_MAP_TYPE_ARRAY);
20	__uint(max_entries, 1);
21	__type(key, int);
22	__type(value, int);
23} results SEC(".maps");
24
25SEC("tp/raw_syscalls/sys_enter")
26int handle_sys_enter(void *ctx)
27{
28	struct task_struct *task = (void *)bpf_get_current_task();
29	int tgid = BPF_CORE_READ(task, tgid);
30	int zero = 0;
31	int real_tgid = bpf_get_current_pid_tgid() >> 32;
32	int *exp_tgid = bpf_map_lookup_elem(&exp_tgid_map, &zero);
33
34	/* only pass through sys_enters from test process */
35	if (!exp_tgid || *exp_tgid != real_tgid)
36		return 0;
37
38	bpf_map_update_elem(&results, &zero, &tgid, 0);
39
40	return 0;
41}
42
43char _license[] SEC("license") = "GPL";
44