pkcs7_key_type.c

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2/* Testing module to load key from trusted PKCS#7 message
 3 *
 4 * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
 5 * Written by David Howells (dhowells@redhat.com)
 6 */
 7
 8#define pr_fmt(fmt) "PKCS7key: "fmt
 9#include <linux/key.h>
10#include <linux/err.h>
11#include <linux/module.h>
12#include <linux/verification.h>
13#include <linux/key-type.h>
14#include <keys/user-type.h>
15
16MODULE_LICENSE("GPL");
17MODULE_DESCRIPTION("PKCS#7 testing key type");
18MODULE_AUTHOR("Red Hat, Inc.");
19
20static unsigned pkcs7_usage;
21module_param_named(usage, pkcs7_usage, uint, S_IWUSR | S_IRUGO);
22MODULE_PARM_DESC(pkcs7_usage,
23		 "Usage to specify when verifying the PKCS#7 message");
24
25/*
26 * Retrieve the PKCS#7 message content.
27 */
28static int pkcs7_view_content(void *ctx, const void *data, size_t len,
29			      size_t asn1hdrlen)
30{
31	struct key_preparsed_payload *prep = ctx;
32	const void *saved_prep_data;
33	size_t saved_prep_datalen;
34	int ret;
35
36	saved_prep_data = prep->data;
37	saved_prep_datalen = prep->datalen;
38	prep->data = data;
39	prep->datalen = len;
40
41	ret = user_preparse(prep);
42
43	prep->data = saved_prep_data;
44	prep->datalen = saved_prep_datalen;
45	return ret;
46}
47
48/*
49 * Preparse a PKCS#7 wrapped and validated data blob.
50 */
51static int pkcs7_preparse(struct key_preparsed_payload *prep)
52{
53	enum key_being_used_for usage = pkcs7_usage;
54
55	if (usage >= NR__KEY_BEING_USED_FOR) {
56		pr_err("Invalid usage type %d\n", usage);
57		return -EINVAL;
58	}
59
60	return verify_pkcs7_signature(NULL, 0,
61				      prep->data, prep->datalen,
62				      VERIFY_USE_SECONDARY_KEYRING, usage,
63				      pkcs7_view_content, prep);
64}
65
66/*
67 * user defined keys take an arbitrary string as the description and an
68 * arbitrary blob of data as the payload
69 */
70static struct key_type key_type_pkcs7 = {
71	.name			= "pkcs7_test",
72	.preparse		= pkcs7_preparse,
73	.free_preparse		= user_free_preparse,
74	.instantiate		= generic_key_instantiate,
75	.revoke			= user_revoke,
76	.destroy		= user_destroy,
77	.describe		= user_describe,
78	.read			= user_read,
79};
80
81/*
82 * Module stuff
83 */
84static int __init pkcs7_key_init(void)
85{
86	return register_key_type(&key_type_pkcs7);
87}
88
89static void __exit pkcs7_key_cleanup(void)
90{
91	unregister_key_type(&key_type_pkcs7);
92}
93
94module_init(pkcs7_key_init);
95module_exit(pkcs7_key_cleanup);