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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 <linux/slab.h> | |
18 | #include <linux/verification.h> | |
19 | #include <keys/asymmetric-type.h> | |
20 | #include <keys/system_keyring.h> | |
21 | #include <crypto/pkcs7.h> | |
22 | #include "internal.h" | |
23 | ||
24 | static struct key *builtin_trusted_keys; | |
25 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
26 | static struct key *secondary_trusted_keys; | |
27 | #endif | |
28 | ||
29 | extern __initconst const u8 system_certificate_list[]; | |
30 | extern __initconst const unsigned long system_certificate_list_size; | |
31 | ||
32 | /** | |
33 | * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA | |
34 | * | |
35 | * Restrict the addition of keys into a keyring based on the key-to-be-added | |
36 | * being vouched for by a key in the built in system keyring. | |
37 | */ | |
38 | int restrict_link_by_builtin_trusted(struct key *dest_keyring, | |
39 | const struct key_type *type, | |
40 | const union key_payload *payload, | |
41 | struct key *restriction_key) | |
42 | { | |
43 | return restrict_link_by_signature(dest_keyring, type, payload, | |
44 | builtin_trusted_keys); | |
45 | } | |
46 | ||
47 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
48 | /** | |
49 | * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring | |
50 | * addition by both builtin and secondary keyrings | |
51 | * | |
52 | * Restrict the addition of keys into a keyring based on the key-to-be-added | |
53 | * being vouched for by a key in either the built-in or the secondary system | |
54 | * keyrings. | |
55 | */ | |
56 | int restrict_link_by_builtin_and_secondary_trusted( | |
57 | struct key *dest_keyring, | |
58 | const struct key_type *type, | |
59 | const union key_payload *payload, | |
60 | struct key *restrict_key) | |
61 | { | |
62 | /* If we have a secondary trusted keyring, then that contains a link | |
63 | * through to the builtin keyring and the search will follow that link. | |
64 | */ | |
65 | if (type == &key_type_keyring && | |
66 | dest_keyring == secondary_trusted_keys && | |
67 | payload == &builtin_trusted_keys->payload) | |
68 | /* Allow the builtin keyring to be added to the secondary */ | |
69 | return 0; | |
70 | ||
71 | return restrict_link_by_signature(dest_keyring, type, payload, | |
72 | secondary_trusted_keys); | |
73 | } | |
74 | ||
75 | /** | |
76 | * Allocate a struct key_restriction for the "builtin and secondary trust" | |
77 | * keyring. Only for use in system_trusted_keyring_init(). | |
78 | */ | |
79 | static __init struct key_restriction *get_builtin_and_secondary_restriction(void) | |
80 | { | |
81 | struct key_restriction *restriction; | |
82 | ||
83 | restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL); | |
84 | ||
85 | if (!restriction) | |
86 | panic("Can't allocate secondary trusted keyring restriction\n"); | |
87 | ||
88 | restriction->check = restrict_link_by_builtin_and_secondary_trusted; | |
89 | ||
90 | return restriction; | |
91 | } | |
92 | #endif | |
93 | ||
94 | /* | |
95 | * Create the trusted keyrings | |
96 | */ | |
97 | static __init int system_trusted_keyring_init(void) | |
98 | { | |
99 | pr_notice("Initialise system trusted keyrings\n"); | |
100 | ||
101 | builtin_trusted_keys = | |
102 | keyring_alloc(".builtin_trusted_keys", | |
103 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), | |
104 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
105 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), | |
106 | KEY_ALLOC_NOT_IN_QUOTA, | |
107 | NULL, NULL); | |
108 | if (IS_ERR(builtin_trusted_keys)) | |
109 | panic("Can't allocate builtin trusted keyring\n"); | |
110 | ||
111 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
112 | secondary_trusted_keys = | |
113 | keyring_alloc(".secondary_trusted_keys", | |
114 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), | |
115 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
116 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | | |
117 | KEY_USR_WRITE), | |
118 | KEY_ALLOC_NOT_IN_QUOTA, | |
119 | get_builtin_and_secondary_restriction(), | |
120 | NULL); | |
121 | if (IS_ERR(secondary_trusted_keys)) | |
122 | panic("Can't allocate secondary trusted keyring\n"); | |
123 | ||
124 | if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) | |
125 | panic("Can't link trusted keyrings\n"); | |
126 | #endif | |
127 | ||
128 | return 0; | |
129 | } | |
130 | ||
131 | /* | |
132 | * Must be initialised before we try and load the keys into the keyring. | |
133 | */ | |
134 | device_initcall(system_trusted_keyring_init); | |
135 | ||
136 | /* | |
137 | * Load the compiled-in list of X.509 certificates. | |
138 | */ | |
139 | static __init int load_system_certificate_list(void) | |
140 | { | |
141 | key_ref_t key; | |
142 | const u8 *p, *end; | |
143 | size_t plen; | |
144 | ||
145 | pr_notice("Loading compiled-in X.509 certificates\n"); | |
146 | ||
147 | p = system_certificate_list; | |
148 | end = p + system_certificate_list_size; | |
149 | while (p < end) { | |
150 | /* Each cert begins with an ASN.1 SEQUENCE tag and must be more | |
151 | * than 256 bytes in size. | |
152 | */ | |
153 | if (end - p < 4) | |
154 | goto dodgy_cert; | |
155 | if (p[0] != 0x30 && | |
156 | p[1] != 0x82) | |
157 | goto dodgy_cert; | |
158 | plen = (p[2] << 8) | p[3]; | |
159 | plen += 4; | |
160 | if (plen > end - p) | |
161 | goto dodgy_cert; | |
162 | ||
163 | key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1), | |
164 | "asymmetric", | |
165 | NULL, | |
166 | p, | |
167 | plen, | |
168 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
169 | KEY_USR_VIEW | KEY_USR_READ), | |
170 | KEY_ALLOC_NOT_IN_QUOTA | | |
171 | KEY_ALLOC_BUILT_IN | | |
172 | KEY_ALLOC_BYPASS_RESTRICTION); | |
173 | if (IS_ERR(key)) { | |
174 | pr_err("Problem loading in-kernel X.509 certificate (%ld)\n", | |
175 | PTR_ERR(key)); | |
176 | WARN_ON_ONCE(1); | |
177 | } else { | |
178 | pr_notice("Loaded X.509 cert '%s'\n", | |
179 | key_ref_to_ptr(key)->description); | |
180 | key_ref_put(key); | |
181 | } | |
182 | p += plen; | |
183 | } | |
184 | ||
185 | return 0; | |
186 | ||
187 | dodgy_cert: | |
188 | pr_err("Problem parsing in-kernel X.509 certificate list\n"); | |
189 | return 0; | |
190 | } | |
191 | late_initcall(load_system_certificate_list); | |
192 | ||
193 | #ifdef CONFIG_SYSTEM_DATA_VERIFICATION | |
194 | ||
195 | /** | |
196 | * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. | |
197 | * @data: The data to be verified (NULL if expecting internal data). | |
198 | * @len: Size of @data. | |
199 | * @raw_pkcs7: The PKCS#7 message that is the signature. | |
200 | * @pkcs7_len: The size of @raw_pkcs7. | |
201 | * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, | |
202 | * (void *)1UL for all trusted keys). | |
203 | * @usage: The use to which the key is being put. | |
204 | * @view_content: Callback to gain access to content. | |
205 | * @ctx: Context for callback. | |
206 | */ | |
207 | int verify_pkcs7_signature(const void *data, size_t len, | |
208 | const void *raw_pkcs7, size_t pkcs7_len, | |
209 | struct key *trusted_keys, | |
210 | enum key_being_used_for usage, | |
211 | int (*view_content)(void *ctx, | |
212 | const void *data, size_t len, | |
213 | size_t asn1hdrlen), | |
214 | void *ctx) | |
215 | { | |
216 | struct pkcs7_message *pkcs7; | |
217 | int ret; | |
218 | ||
219 | pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); | |
220 | if (IS_ERR(pkcs7)) | |
221 | return PTR_ERR(pkcs7); | |
222 | ||
223 | /* The data should be detached - so we need to supply it. */ | |
224 | if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { | |
225 | pr_err("PKCS#7 signature with non-detached data\n"); | |
226 | ret = -EBADMSG; | |
227 | goto error; | |
228 | } | |
229 | ||
230 | ret = pkcs7_verify(pkcs7, usage); | |
231 | if (ret < 0) | |
232 | goto error; | |
233 | ||
234 | if (!trusted_keys) { | |
235 | trusted_keys = builtin_trusted_keys; | |
236 | } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { | |
237 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
238 | trusted_keys = secondary_trusted_keys; | |
239 | #else | |
240 | trusted_keys = builtin_trusted_keys; | |
241 | #endif | |
242 | } | |
243 | ret = pkcs7_validate_trust(pkcs7, trusted_keys); | |
244 | if (ret < 0) { | |
245 | if (ret == -ENOKEY) | |
246 | pr_err("PKCS#7 signature not signed with a trusted key\n"); | |
247 | goto error; | |
248 | } | |
249 | ||
250 | if (view_content) { | |
251 | size_t asn1hdrlen; | |
252 | ||
253 | ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); | |
254 | if (ret < 0) { | |
255 | if (ret == -ENODATA) | |
256 | pr_devel("PKCS#7 message does not contain data\n"); | |
257 | goto error; | |
258 | } | |
259 | ||
260 | ret = view_content(ctx, data, len, asn1hdrlen); | |
261 | } | |
262 | ||
263 | error: | |
264 | pkcs7_free_message(pkcs7); | |
265 | pr_devel("<==%s() = %d\n", __func__, ret); | |
266 | return ret; | |
267 | } | |
268 | EXPORT_SYMBOL_GPL(verify_pkcs7_signature); | |
269 | ||
270 | #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ | |
271 | ||
272 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
273 | /** | |
274 | * add_trusted_secondary_key - Add to secondary keyring with no validation | |
275 | * @source: Source of key | |
276 | * @data: The blob holding the key | |
277 | * @len: The length of the data blob | |
278 | * | |
279 | * Add a key to the secondary keyring without checking its trust chain. This | |
280 | * is available only during kernel initialisation. | |
281 | */ | |
282 | void __init add_trusted_secondary_key(const char *source, | |
283 | const void *data, size_t len) | |
284 | { | |
285 | key_ref_t key; | |
286 | ||
287 | key = key_create_or_update(make_key_ref(secondary_trusted_keys, 1), | |
288 | "asymmetric", | |
289 | NULL, data, len, | |
290 | (KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
291 | KEY_USR_VIEW, | |
292 | KEY_ALLOC_NOT_IN_QUOTA | | |
293 | KEY_ALLOC_BYPASS_RESTRICTION); | |
294 | ||
295 | if (IS_ERR(key)) | |
296 | pr_err("Problem loading %s X.509 certificate (%ld)\n", | |
297 | source, PTR_ERR(key)); | |
298 | else | |
299 | pr_notice("Loaded %s cert '%s' linked to secondary sys keyring\n", | |
300 | source, key_ref_to_ptr(key)->description); | |
301 | } | |
302 | #endif /* CONFIG_SECONDARY_TRUSTED_KEYRING */ |