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 extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
15 extern void bpf_key_put(struct bpf_key *key) __ksym;
16 extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr,
17 struct bpf_dynptr *sig_ptr,
18 struct bpf_key *trusted_keyring) __ksym;
19
20 struct {
21 __uint(type, BPF_MAP_TYPE_RINGBUF);
22 } ringbuf SEC(".maps");
23
24 struct {
25 __uint(type, BPF_MAP_TYPE_ARRAY);
26 __uint(max_entries, 1);
27 __type(key, __u32);
28 __type(value, __u32);
29 } array_map SEC(".maps");
30
31 int err, pid;
32
33 char _license[] SEC("license") = "GPL";
34
35 SEC("?lsm.s/bpf")
BPF_PROG(dynptr_type_not_supp,int cmd,union bpf_attr * attr,unsigned int size)36 int BPF_PROG(dynptr_type_not_supp, int cmd, union bpf_attr *attr,
37 unsigned int size)
38 {
39 char write_data[64] = "hello there, world!!";
40 struct bpf_dynptr ptr;
41
42 bpf_ringbuf_reserve_dynptr(&ringbuf, sizeof(write_data), 0, &ptr);
43
44 return bpf_verify_pkcs7_signature(&ptr, &ptr, NULL);
45 }
46
47 SEC("?lsm.s/bpf")
BPF_PROG(not_valid_dynptr,int cmd,union bpf_attr * attr,unsigned int size)48 int BPF_PROG(not_valid_dynptr, int cmd, union bpf_attr *attr, unsigned int size)
49 {
50 unsigned long val;
51
52 return bpf_verify_pkcs7_signature((struct bpf_dynptr *)&val,
53 (struct bpf_dynptr *)&val, NULL);
54 }
55
56 SEC("?lsm.s/bpf")
BPF_PROG(not_ptr_to_stack,int cmd,union bpf_attr * attr,unsigned int size)57 int BPF_PROG(not_ptr_to_stack, int cmd, union bpf_attr *attr, unsigned int size)
58 {
59 unsigned long val;
60
61 return bpf_verify_pkcs7_signature((struct bpf_dynptr *)val,
62 (struct bpf_dynptr *)val, NULL);
63 }
64
65 SEC("lsm.s/bpf")
BPF_PROG(dynptr_data_null,int cmd,union bpf_attr * attr,unsigned int size)66 int BPF_PROG(dynptr_data_null, int cmd, union bpf_attr *attr, unsigned int size)
67 {
68 struct bpf_key *trusted_keyring;
69 struct bpf_dynptr ptr;
70 __u32 *value;
71 int ret, zero = 0;
72
73 if (bpf_get_current_pid_tgid() >> 32 != pid)
74 return 0;
75
76 value = bpf_map_lookup_elem(&array_map, &zero);
77 if (!value)
78 return 0;
79
80 /* Pass invalid flags. */
81 ret = bpf_dynptr_from_mem(value, sizeof(*value), ((__u64)~0ULL), &ptr);
82 if (ret != -EINVAL)
83 return 0;
84
85 trusted_keyring = bpf_lookup_system_key(0);
86 if (!trusted_keyring)
87 return 0;
88
89 err = bpf_verify_pkcs7_signature(&ptr, &ptr, trusted_keyring);
90
91 bpf_key_put(trusted_keyring);
92
93 return 0;
94 }
95