1 /* Testing module to load key from trusted PKCS#7 message
2  *
3  * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells (dhowells@redhat.com)
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public Licence
8  * as published by the Free Software Foundation; either version
9  * 2 of the Licence, or (at your option) any later version.
10  */
11 
12 #define pr_fmt(fmt) "PKCS7key: "fmt
13 #include <linux/key.h>
14 #include <linux/err.h>
15 #include <linux/module.h>
16 #include <linux/verification.h>
17 #include <linux/key-type.h>
18 #include <keys/user-type.h>
19 
20 MODULE_LICENSE("GPL");
21 MODULE_DESCRIPTION("PKCS#7 testing key type");
22 MODULE_AUTHOR("Red Hat, Inc.");
23 
24 static unsigned pkcs7_usage;
25 module_param_named(usage, pkcs7_usage, uint, S_IWUSR | S_IRUGO);
26 MODULE_PARM_DESC(pkcs7_usage,
27 		 "Usage to specify when verifying the PKCS#7 message");
28 
29 /*
30  * Retrieve the PKCS#7 message content.
31  */
32 static int pkcs7_view_content(void *ctx, const void *data, size_t len,
33 			      size_t asn1hdrlen)
34 {
35 	struct key_preparsed_payload *prep = ctx;
36 	const void *saved_prep_data;
37 	size_t saved_prep_datalen;
38 	int ret;
39 
40 	saved_prep_data = prep->data;
41 	saved_prep_datalen = prep->datalen;
42 	prep->data = data;
43 	prep->datalen = len;
44 
45 	ret = user_preparse(prep);
46 
47 	prep->data = saved_prep_data;
48 	prep->datalen = saved_prep_datalen;
49 	return ret;
50 }
51 
52 /*
53  * Preparse a PKCS#7 wrapped and validated data blob.
54  */
55 static int pkcs7_preparse(struct key_preparsed_payload *prep)
56 {
57 	enum key_being_used_for usage = pkcs7_usage;
58 
59 	if (usage >= NR__KEY_BEING_USED_FOR) {
60 		pr_err("Invalid usage type %d\n", usage);
61 		return -EINVAL;
62 	}
63 
64 	return verify_pkcs7_signature(NULL, 0,
65 				      prep->data, prep->datalen,
66 				      (void *)1UL, usage,
67 				      pkcs7_view_content, prep);
68 }
69 
70 /*
71  * user defined keys take an arbitrary string as the description and an
72  * arbitrary blob of data as the payload
73  */
74 static struct key_type key_type_pkcs7 = {
75 	.name			= "pkcs7_test",
76 	.preparse		= pkcs7_preparse,
77 	.free_preparse		= user_free_preparse,
78 	.instantiate		= generic_key_instantiate,
79 	.revoke			= user_revoke,
80 	.destroy		= user_destroy,
81 	.describe		= user_describe,
82 	.read			= user_read,
83 };
84 
85 /*
86  * Module stuff
87  */
88 static int __init pkcs7_key_init(void)
89 {
90 	return register_key_type(&key_type_pkcs7);
91 }
92 
93 static void __exit pkcs7_key_cleanup(void)
94 {
95 	unregister_key_type(&key_type_pkcs7);
96 }
97 
98 module_init(pkcs7_key_init);
99 module_exit(pkcs7_key_cleanup);
100