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#include "bpf_misc.h"
14
15extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
16extern void bpf_key_put(struct bpf_key *key) __ksym;
17extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr,
18 struct bpf_dynptr *sig_ptr,
19 struct bpf_key *trusted_keyring) __ksym;
20
21struct {
22 __uint(type, BPF_MAP_TYPE_RINGBUF);
23 __uint(max_entries, 4096);
24} ringbuf SEC(".maps");
25
26struct {
27 __uint(type, BPF_MAP_TYPE_ARRAY);
28 __uint(max_entries, 1);
29 __type(key, __u32);
30 __type(value, __u32);
31} array_map SEC(".maps");
32
33int err, pid;
34
35char _license[] SEC("license") = "GPL";
36
37SEC("?lsm.s/bpf")
38__failure __msg("cannot pass in dynptr at an offset=-8")
39int BPF_PROG(not_valid_dynptr, int cmd, union bpf_attr *attr, unsigned int size)
40{
41 unsigned long val;
42
43 return bpf_verify_pkcs7_signature((struct bpf_dynptr *)&val,
44 (struct bpf_dynptr *)&val, NULL);
45}
46
47SEC("?lsm.s/bpf")
48__failure __msg("arg#0 expected pointer to stack or dynptr_ptr")
49int BPF_PROG(not_ptr_to_stack, int cmd, union bpf_attr *attr, unsigned int size)
50{
51 unsigned long val = 0;
52
53 return bpf_verify_pkcs7_signature((struct bpf_dynptr *)val,
54 (struct bpf_dynptr *)val, NULL);
55}
56
57SEC("lsm.s/bpf")
58int BPF_PROG(dynptr_data_null, int cmd, union bpf_attr *attr, unsigned int size)
59{
60 struct bpf_key *trusted_keyring;
61 struct bpf_dynptr ptr;
62 __u32 *value;
63 int ret, zero = 0;
64
65 if (bpf_get_current_pid_tgid() >> 32 != pid)
66 return 0;
67
68 value = bpf_map_lookup_elem(&array_map, &zero);
69 if (!value)
70 return 0;
71
72 /* Pass invalid flags. */
73 ret = bpf_dynptr_from_mem(value, sizeof(*value), ((__u64)~0ULL), &ptr);
74 if (ret != -EINVAL)
75 return 0;
76
77 trusted_keyring = bpf_lookup_system_key(0);
78 if (!trusted_keyring)
79 return 0;
80
81 err = bpf_verify_pkcs7_signature(&ptr, &ptr, trusted_keyring);
82
83 bpf_key_put(trusted_keyring);
84
85 return 0;
86}
87

source code of linux/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c