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 
7 struct task_struct {
8 	int tgid;
9 } __attribute__((preserve_access_index));
10 
11 struct {
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 
18 struct {
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 
25 SEC("tp/raw_syscalls/sys_enter")
26 int 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 
43 char _license[] SEC("license") = "GPL";
44