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b56e5a17 DH |
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> | |
091f6e26 | 19 | #include <crypto/pkcs7.h> |
b56e5a17 | 20 | |
d3bfe841 DH |
21 | static struct key *builtin_trusted_keys; |
22 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
23 | static struct key *secondary_trusted_keys; | |
24 | #endif | |
177a18d1 JB |
25 | #ifdef CONFIG_SYSTEM_BLACKLIST_KEYRING |
26 | struct key *system_blacklist_keyring; | |
27 | #endif | |
b56e5a17 DH |
28 | |
29 | extern __initconst const u8 system_certificate_list[]; | |
62226983 | 30 | extern __initconst const unsigned long system_certificate_list_size; |
b56e5a17 | 31 | |
16eb7765 JB |
32 | /** |
33 | * get_system_keyring - Return a pointer to the system keyring | |
34 | * | |
35 | */ | |
36 | struct key *get_system_keyring(void) | |
37 | { | |
38 | struct key *system_keyring = NULL; | |
39 | ||
40 | system_keyring = builtin_trusted_keys; | |
41 | return system_keyring; | |
42 | } | |
43 | EXPORT_SYMBOL_GPL(get_system_keyring); | |
44 | ||
a511e1af | 45 | /** |
d3bfe841 | 46 | * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA |
a511e1af DH |
47 | * |
48 | * Restrict the addition of keys into a keyring based on the key-to-be-added | |
d3bfe841 | 49 | * being vouched for by a key in the built in system keyring. |
a511e1af DH |
50 | */ |
51 | int restrict_link_by_builtin_trusted(struct key *keyring, | |
52 | const struct key_type *type, | |
a511e1af DH |
53 | const union key_payload *payload) |
54 | { | |
d3bfe841 | 55 | return restrict_link_by_signature(builtin_trusted_keys, type, payload); |
a511e1af DH |
56 | } |
57 | ||
d3bfe841 DH |
58 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
59 | /** | |
60 | * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring | |
61 | * addition by both builtin and secondary keyrings | |
62 | * | |
63 | * Restrict the addition of keys into a keyring based on the key-to-be-added | |
64 | * being vouched for by a key in either the built-in or the secondary system | |
65 | * keyrings. | |
66 | */ | |
67 | int restrict_link_by_builtin_and_secondary_trusted( | |
68 | struct key *keyring, | |
69 | const struct key_type *type, | |
70 | const union key_payload *payload) | |
71 | { | |
72 | /* If we have a secondary trusted keyring, then that contains a link | |
73 | * through to the builtin keyring and the search will follow that link. | |
74 | */ | |
75 | if (type == &key_type_keyring && | |
76 | keyring == secondary_trusted_keys && | |
77 | payload == &builtin_trusted_keys->payload) | |
78 | /* Allow the builtin keyring to be added to the secondary */ | |
79 | return 0; | |
80 | ||
81 | return restrict_link_by_signature(secondary_trusted_keys, type, payload); | |
82 | } | |
83 | #endif | |
84 | ||
b56e5a17 | 85 | /* |
d3bfe841 | 86 | * Create the trusted keyrings |
b56e5a17 DH |
87 | */ |
88 | static __init int system_trusted_keyring_init(void) | |
89 | { | |
d3bfe841 | 90 | pr_notice("Initialise system trusted keyrings\n"); |
b56e5a17 | 91 | |
d3bfe841 DH |
92 | builtin_trusted_keys = |
93 | keyring_alloc(".builtin_trusted_keys", | |
b56e5a17 DH |
94 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), |
95 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
af34cb0c | 96 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), |
5ac7eace | 97 | KEY_ALLOC_NOT_IN_QUOTA, |
d3bfe841 DH |
98 | NULL, NULL); |
99 | if (IS_ERR(builtin_trusted_keys)) | |
100 | panic("Can't allocate builtin trusted keyring\n"); | |
101 | ||
102 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
103 | secondary_trusted_keys = | |
104 | keyring_alloc(".secondary_trusted_keys", | |
105 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), | |
106 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
107 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | | |
108 | KEY_USR_WRITE), | |
109 | KEY_ALLOC_NOT_IN_QUOTA, | |
110 | restrict_link_by_builtin_and_secondary_trusted, | |
111 | NULL); | |
112 | if (IS_ERR(secondary_trusted_keys)) | |
113 | panic("Can't allocate secondary trusted keyring\n"); | |
114 | ||
115 | if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) | |
116 | panic("Can't link trusted keyrings\n"); | |
117 | #endif | |
177a18d1 JB |
118 | #ifdef CONFIG_SYSTEM_BLACKLIST_KEYRING |
119 | system_blacklist_keyring = keyring_alloc(".system_blacklist_keyring", | |
120 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), | |
121 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
122 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), | |
123 | KEY_ALLOC_NOT_IN_QUOTA, | |
124 | NULL, NULL); | |
125 | if (IS_ERR(system_blacklist_keyring)) | |
126 | panic("Can't allocate system blacklist keyring\n"); | |
127 | #endif | |
d3bfe841 | 128 | |
b56e5a17 DH |
129 | return 0; |
130 | } | |
131 | ||
132 | /* | |
133 | * Must be initialised before we try and load the keys into the keyring. | |
134 | */ | |
135 | device_initcall(system_trusted_keyring_init); | |
136 | ||
137 | /* | |
138 | * Load the compiled-in list of X.509 certificates. | |
139 | */ | |
140 | static __init int load_system_certificate_list(void) | |
141 | { | |
142 | key_ref_t key; | |
143 | const u8 *p, *end; | |
144 | size_t plen; | |
145 | ||
146 | pr_notice("Loading compiled-in X.509 certificates\n"); | |
147 | ||
b56e5a17 | 148 | p = system_certificate_list; |
62226983 | 149 | end = p + system_certificate_list_size; |
b56e5a17 DH |
150 | while (p < end) { |
151 | /* Each cert begins with an ASN.1 SEQUENCE tag and must be more | |
152 | * than 256 bytes in size. | |
153 | */ | |
154 | if (end - p < 4) | |
155 | goto dodgy_cert; | |
156 | if (p[0] != 0x30 && | |
157 | p[1] != 0x82) | |
158 | goto dodgy_cert; | |
159 | plen = (p[2] << 8) | p[3]; | |
160 | plen += 4; | |
161 | if (plen > end - p) | |
162 | goto dodgy_cert; | |
163 | ||
d3bfe841 | 164 | key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1), |
b56e5a17 DH |
165 | "asymmetric", |
166 | NULL, | |
167 | p, | |
168 | plen, | |
af34cb0c MZ |
169 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
170 | KEY_USR_VIEW | KEY_USR_READ), | |
008643b8 | 171 | KEY_ALLOC_NOT_IN_QUOTA | |
5ac7eace DH |
172 | KEY_ALLOC_BUILT_IN | |
173 | KEY_ALLOC_BYPASS_RESTRICTION); | |
b56e5a17 DH |
174 | if (IS_ERR(key)) { |
175 | pr_err("Problem loading in-kernel X.509 certificate (%ld)\n", | |
176 | PTR_ERR(key)); | |
ca6088d8 | 177 | WARN_ON_ONCE(1); |
b56e5a17 DH |
178 | } else { |
179 | pr_notice("Loaded X.509 cert '%s'\n", | |
180 | key_ref_to_ptr(key)->description); | |
181 | key_ref_put(key); | |
182 | } | |
183 | p += plen; | |
184 | } | |
185 | ||
186 | return 0; | |
187 | ||
188 | dodgy_cert: | |
189 | pr_err("Problem parsing in-kernel X.509 certificate list\n"); | |
190 | return 0; | |
191 | } | |
192 | late_initcall(load_system_certificate_list); | |
091f6e26 DH |
193 | |
194 | #ifdef CONFIG_SYSTEM_DATA_VERIFICATION | |
195 | ||
196 | /** | |
e68503bd DH |
197 | * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. |
198 | * @data: The data to be verified (NULL if expecting internal data). | |
091f6e26 DH |
199 | * @len: Size of @data. |
200 | * @raw_pkcs7: The PKCS#7 message that is the signature. | |
201 | * @pkcs7_len: The size of @raw_pkcs7. | |
d3bfe841 DH |
202 | * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, |
203 | * (void *)1UL for all trusted keys). | |
99db4435 | 204 | * @usage: The use to which the key is being put. |
e68503bd DH |
205 | * @view_content: Callback to gain access to content. |
206 | * @ctx: Context for callback. | |
091f6e26 | 207 | */ |
e68503bd DH |
208 | int verify_pkcs7_signature(const void *data, size_t len, |
209 | const void *raw_pkcs7, size_t pkcs7_len, | |
210 | struct key *trusted_keys, | |
e68503bd DH |
211 | enum key_being_used_for usage, |
212 | int (*view_content)(void *ctx, | |
213 | const void *data, size_t len, | |
214 | size_t asn1hdrlen), | |
215 | void *ctx) | |
091f6e26 DH |
216 | { |
217 | struct pkcs7_message *pkcs7; | |
091f6e26 DH |
218 | int ret; |
219 | ||
220 | pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); | |
221 | if (IS_ERR(pkcs7)) | |
222 | return PTR_ERR(pkcs7); | |
223 | ||
224 | /* The data should be detached - so we need to supply it. */ | |
e68503bd | 225 | if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { |
091f6e26 DH |
226 | pr_err("PKCS#7 signature with non-detached data\n"); |
227 | ret = -EBADMSG; | |
228 | goto error; | |
229 | } | |
230 | ||
99db4435 | 231 | ret = pkcs7_verify(pkcs7, usage); |
091f6e26 DH |
232 | if (ret < 0) |
233 | goto error; | |
234 | ||
d3bfe841 DH |
235 | if (!trusted_keys) { |
236 | trusted_keys = builtin_trusted_keys; | |
237 | } else if (trusted_keys == (void *)1UL) { | |
238 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
239 | trusted_keys = secondary_trusted_keys; | |
240 | #else | |
241 | trusted_keys = builtin_trusted_keys; | |
242 | #endif | |
243 | } | |
177a18d1 JB |
244 | #ifdef CONFIG_SYSTEM_BLACKLIST_KEYRING |
245 | ret = pkcs7_validate_trust(pkcs7, system_blacklist_keyring); | |
246 | if (!ret) { | |
247 | /* module is signed with a cert in the blacklist. reject */ | |
248 | pr_err("Module key is in the blacklist\n"); | |
249 | ret = -EKEYREJECTED; | |
250 | goto error; | |
251 | } | |
252 | #endif | |
bda850cd DH |
253 | ret = pkcs7_validate_trust(pkcs7, trusted_keys); |
254 | if (ret < 0) { | |
255 | if (ret == -ENOKEY) | |
256 | pr_err("PKCS#7 signature not signed with a trusted key\n"); | |
e68503bd DH |
257 | goto error; |
258 | } | |
259 | ||
260 | if (view_content) { | |
261 | size_t asn1hdrlen; | |
262 | ||
263 | ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); | |
264 | if (ret < 0) { | |
265 | if (ret == -ENODATA) | |
266 | pr_devel("PKCS#7 message does not contain data\n"); | |
267 | goto error; | |
268 | } | |
269 | ||
270 | ret = view_content(ctx, data, len, asn1hdrlen); | |
091f6e26 DH |
271 | } |
272 | ||
273 | error: | |
274 | pkcs7_free_message(pkcs7); | |
275 | pr_devel("<==%s() = %d\n", __func__, ret); | |
276 | return ret; | |
277 | } | |
e68503bd | 278 | EXPORT_SYMBOL_GPL(verify_pkcs7_signature); |
091f6e26 DH |
279 | |
280 | #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ |