1 /* System trusted keyring for trusted public keys
2 *
3 * Copyright (C) 2012 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 #include <linux/export.h>
13 #include <linux/kernel.h>
14 #include <linux/sched.h>
15 #include <linux/cred.h>
16 #include <linux/err.h>
17 #include <keys/asymmetric-type.h>
18 #include <keys/system_keyring.h>
19 #include <crypto/pkcs7.h>
20
21 struct key *system_trusted_keyring;
22 EXPORT_SYMBOL_GPL(system_trusted_keyring);
23
24 extern __initconst const u8 system_certificate_list[];
25 extern __initconst const unsigned long system_certificate_list_size;
26
27 /*
28 * Load the compiled-in keys
29 */
system_trusted_keyring_init(void)30 static __init int system_trusted_keyring_init(void)
31 {
32 pr_notice("Initialise system trusted keyring\n");
33
34 system_trusted_keyring =
35 keyring_alloc(".system_keyring",
36 KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
37 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
38 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
39 KEY_ALLOC_NOT_IN_QUOTA, NULL);
40 if (IS_ERR(system_trusted_keyring))
41 panic("Can't allocate system trusted keyring\n");
42
43 set_bit(KEY_FLAG_TRUSTED_ONLY, &system_trusted_keyring->flags);
44 return 0;
45 }
46
47 /*
48 * Must be initialised before we try and load the keys into the keyring.
49 */
50 device_initcall(system_trusted_keyring_init);
51
52 /*
53 * Load the compiled-in list of X.509 certificates.
54 */
load_system_certificate_list(void)55 static __init int load_system_certificate_list(void)
56 {
57 key_ref_t key;
58 const u8 *p, *end;
59 size_t plen;
60
61 pr_notice("Loading compiled-in X.509 certificates\n");
62
63 p = system_certificate_list;
64 end = p + system_certificate_list_size;
65 while (p < end) {
66 /* Each cert begins with an ASN.1 SEQUENCE tag and must be more
67 * than 256 bytes in size.
68 */
69 if (end - p < 4)
70 goto dodgy_cert;
71 if (p[0] != 0x30 &&
72 p[1] != 0x82)
73 goto dodgy_cert;
74 plen = (p[2] << 8) | p[3];
75 plen += 4;
76 if (plen > end - p)
77 goto dodgy_cert;
78
79 key = key_create_or_update(make_key_ref(system_trusted_keyring, 1),
80 "asymmetric",
81 NULL,
82 p,
83 plen,
84 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
85 KEY_USR_VIEW | KEY_USR_READ),
86 KEY_ALLOC_NOT_IN_QUOTA |
87 KEY_ALLOC_TRUSTED);
88 if (IS_ERR(key)) {
89 pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
90 PTR_ERR(key));
91 } else {
92 set_bit(KEY_FLAG_BUILTIN, &key_ref_to_ptr(key)->flags);
93 pr_notice("Loaded X.509 cert '%s'\n",
94 key_ref_to_ptr(key)->description);
95 key_ref_put(key);
96 }
97 p += plen;
98 }
99
100 return 0;
101
102 dodgy_cert:
103 pr_err("Problem parsing in-kernel X.509 certificate list\n");
104 return 0;
105 }
106 late_initcall(load_system_certificate_list);
107
108 #ifdef CONFIG_SYSTEM_DATA_VERIFICATION
109
110 /**
111 * Verify a PKCS#7-based signature on system data.
112 * @data: The data to be verified.
113 * @len: Size of @data.
114 * @raw_pkcs7: The PKCS#7 message that is the signature.
115 * @pkcs7_len: The size of @raw_pkcs7.
116 * @usage: The use to which the key is being put.
117 */
system_verify_data(const void * data,unsigned long len,const void * raw_pkcs7,size_t pkcs7_len,enum key_being_used_for usage)118 int system_verify_data(const void *data, unsigned long len,
119 const void *raw_pkcs7, size_t pkcs7_len,
120 enum key_being_used_for usage)
121 {
122 struct pkcs7_message *pkcs7;
123 bool trusted;
124 int ret;
125
126 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
127 if (IS_ERR(pkcs7))
128 return PTR_ERR(pkcs7);
129
130 /* The data should be detached - so we need to supply it. */
131 if (pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
132 pr_err("PKCS#7 signature with non-detached data\n");
133 ret = -EBADMSG;
134 goto error;
135 }
136
137 ret = pkcs7_verify(pkcs7, usage);
138 if (ret < 0)
139 goto error;
140
141 ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);
142 if (ret < 0)
143 goto error;
144
145 if (!trusted) {
146 pr_err("PKCS#7 signature not signed with a trusted key\n");
147 ret = -ENOKEY;
148 }
149
150 error:
151 pkcs7_free_message(pkcs7);
152 pr_devel("<==%s() = %d\n", __func__, ret);
153 return ret;
154 }
155 EXPORT_SYMBOL_GPL(system_verify_data);
156
157 #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
158