1 // SPDX-License-Identifier: GPL-2.0
2 
3 /*
4  * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
5  *
6  * Author: Roberto Sassu <roberto.sassu@huawei.com>
7  */
8 
9 #include "vmlinux.h"
10 #include <errno.h>
11 #include <bpf/bpf_helpers.h>
12 #include <bpf/bpf_tracing.h>
13 
14 char _license[] SEC("license") = "GPL";
15 
16 __u32 monitored_pid;
17 __u32 key_serial;
18 __u32 key_id;
19 __u64 flags;
20 
21 extern struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;
22 extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
23 extern void bpf_key_put(struct bpf_key *key) __ksym;
24 
25 SEC("lsm.s/bpf")
26 int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size)
27 {
28 	struct bpf_key *bkey;
29 	__u32 pid;
30 
31 	pid = bpf_get_current_pid_tgid() >> 32;
32 	if (pid != monitored_pid)
33 		return 0;
34 
35 	if (key_serial)
36 		bkey = bpf_lookup_user_key(key_serial, flags);
37 	else
38 		bkey = bpf_lookup_system_key(key_id);
39 
40 	if (!bkey)
41 		return -ENOENT;
42 
43 	bpf_key_put(bkey);
44 
45 	return 0;
46 }
47