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
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