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1 | // SPDX-License-Identifier: GPL-2.0-or-later | |
2 | /* System trusted keyring for trusted public keys | |
3 | * | |
4 | * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
6 | */ | |
7 | ||
8 | #include <linux/export.h> | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/sched.h> | |
11 | #include <linux/cred.h> | |
12 | #include <linux/err.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/uidgid.h> | |
15 | #include <linux/verification.h> | |
16 | #include <keys/asymmetric-type.h> | |
17 | #include <keys/system_keyring.h> | |
18 | #include <crypto/pkcs7.h> | |
19 | ||
20 | static struct key *builtin_trusted_keys; | |
21 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
22 | static struct key *secondary_trusted_keys; | |
23 | #endif | |
24 | #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING | |
25 | static struct key *machine_trusted_keys; | |
26 | #endif | |
27 | #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING | |
28 | static struct key *platform_trusted_keys; | |
29 | #endif | |
30 | ||
31 | extern __initconst const u8 system_certificate_list[]; | |
32 | extern __initconst const unsigned long system_certificate_list_size; | |
33 | extern __initconst const unsigned long module_cert_size; | |
34 | ||
35 | /** | |
36 | * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA | |
37 | * | |
38 | * Restrict the addition of keys into a keyring based on the key-to-be-added | |
39 | * being vouched for by a key in the built in system keyring. | |
40 | */ | |
41 | int restrict_link_by_builtin_trusted(struct key *dest_keyring, | |
42 | const struct key_type *type, | |
43 | const union key_payload *payload, | |
44 | struct key *restriction_key) | |
45 | { | |
46 | return restrict_link_by_signature(dest_keyring, type, payload, | |
47 | builtin_trusted_keys); | |
48 | } | |
49 | ||
50 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
51 | /** | |
52 | * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring | |
53 | * addition by both builtin and secondary keyrings | |
54 | * | |
55 | * Restrict the addition of keys into a keyring based on the key-to-be-added | |
56 | * being vouched for by a key in either the built-in or the secondary system | |
57 | * keyrings. | |
58 | */ | |
59 | int restrict_link_by_builtin_and_secondary_trusted( | |
60 | struct key *dest_keyring, | |
61 | const struct key_type *type, | |
62 | const union key_payload *payload, | |
63 | struct key *restrict_key) | |
64 | { | |
65 | /* If we have a secondary trusted keyring, then that contains a link | |
66 | * through to the builtin keyring and the search will follow that link. | |
67 | */ | |
68 | if (type == &key_type_keyring && | |
69 | dest_keyring == secondary_trusted_keys && | |
70 | payload == &builtin_trusted_keys->payload) | |
71 | /* Allow the builtin keyring to be added to the secondary */ | |
72 | return 0; | |
73 | ||
74 | return restrict_link_by_signature(dest_keyring, type, payload, | |
75 | secondary_trusted_keys); | |
76 | } | |
77 | ||
78 | /** | |
79 | * Allocate a struct key_restriction for the "builtin and secondary trust" | |
80 | * keyring. Only for use in system_trusted_keyring_init(). | |
81 | */ | |
82 | static __init struct key_restriction *get_builtin_and_secondary_restriction(void) | |
83 | { | |
84 | struct key_restriction *restriction; | |
85 | ||
86 | restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL); | |
87 | ||
88 | if (!restriction) | |
89 | panic("Can't allocate secondary trusted keyring restriction\n"); | |
90 | ||
91 | if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING)) | |
92 | restriction->check = restrict_link_by_builtin_secondary_and_machine; | |
93 | else | |
94 | restriction->check = restrict_link_by_builtin_and_secondary_trusted; | |
95 | ||
96 | return restriction; | |
97 | } | |
98 | #endif | |
99 | #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING | |
100 | void __init set_machine_trusted_keys(struct key *keyring) | |
101 | { | |
102 | machine_trusted_keys = keyring; | |
103 | ||
104 | if (key_link(secondary_trusted_keys, machine_trusted_keys) < 0) | |
105 | panic("Can't link (machine) trusted keyrings\n"); | |
106 | } | |
107 | ||
108 | /** | |
109 | * restrict_link_by_builtin_secondary_and_machine - Restrict keyring addition. | |
110 | * @dest_keyring: Keyring being linked to. | |
111 | * @type: The type of key being added. | |
112 | * @payload: The payload of the new key. | |
113 | * @restrict_key: A ring of keys that can be used to vouch for the new cert. | |
114 | * | |
115 | * Restrict the addition of keys into a keyring based on the key-to-be-added | |
116 | * being vouched for by a key in either the built-in, the secondary, or | |
117 | * the machine keyrings. | |
118 | */ | |
119 | int restrict_link_by_builtin_secondary_and_machine( | |
120 | struct key *dest_keyring, | |
121 | const struct key_type *type, | |
122 | const union key_payload *payload, | |
123 | struct key *restrict_key) | |
124 | { | |
125 | if (machine_trusted_keys && type == &key_type_keyring && | |
126 | dest_keyring == secondary_trusted_keys && | |
127 | payload == &machine_trusted_keys->payload) | |
128 | /* Allow the machine keyring to be added to the secondary */ | |
129 | return 0; | |
130 | ||
131 | return restrict_link_by_builtin_and_secondary_trusted(dest_keyring, type, | |
132 | payload, restrict_key); | |
133 | } | |
134 | #endif | |
135 | ||
136 | /* | |
137 | * Create the trusted keyrings | |
138 | */ | |
139 | static __init int system_trusted_keyring_init(void) | |
140 | { | |
141 | pr_notice("Initialise system trusted keyrings\n"); | |
142 | ||
143 | builtin_trusted_keys = | |
144 | keyring_alloc(".builtin_trusted_keys", | |
145 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), | |
146 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
147 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), | |
148 | KEY_ALLOC_NOT_IN_QUOTA, | |
149 | NULL, NULL); | |
150 | if (IS_ERR(builtin_trusted_keys)) | |
151 | panic("Can't allocate builtin trusted keyring\n"); | |
152 | ||
153 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
154 | secondary_trusted_keys = | |
155 | keyring_alloc(".secondary_trusted_keys", | |
156 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), | |
157 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
158 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | | |
159 | KEY_USR_WRITE), | |
160 | KEY_ALLOC_NOT_IN_QUOTA, | |
161 | get_builtin_and_secondary_restriction(), | |
162 | NULL); | |
163 | if (IS_ERR(secondary_trusted_keys)) | |
164 | panic("Can't allocate secondary trusted keyring\n"); | |
165 | ||
166 | if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) | |
167 | panic("Can't link trusted keyrings\n"); | |
168 | #endif | |
169 | ||
170 | return 0; | |
171 | } | |
172 | ||
173 | /* | |
174 | * Must be initialised before we try and load the keys into the keyring. | |
175 | */ | |
176 | device_initcall(system_trusted_keyring_init); | |
177 | ||
178 | __init int load_module_cert(struct key *keyring) | |
179 | { | |
180 | if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG)) | |
181 | return 0; | |
182 | ||
183 | pr_notice("Loading compiled-in module X.509 certificates\n"); | |
184 | ||
185 | return x509_load_certificate_list(system_certificate_list, | |
186 | module_cert_size, keyring); | |
187 | } | |
188 | ||
189 | /* | |
190 | * Load the compiled-in list of X.509 certificates. | |
191 | */ | |
192 | static __init int load_system_certificate_list(void) | |
193 | { | |
194 | const u8 *p; | |
195 | unsigned long size; | |
196 | ||
197 | pr_notice("Loading compiled-in X.509 certificates\n"); | |
198 | ||
199 | #ifdef CONFIG_MODULE_SIG | |
200 | p = system_certificate_list; | |
201 | size = system_certificate_list_size; | |
202 | #else | |
203 | p = system_certificate_list + module_cert_size; | |
204 | size = system_certificate_list_size - module_cert_size; | |
205 | #endif | |
206 | ||
207 | return x509_load_certificate_list(p, size, builtin_trusted_keys); | |
208 | } | |
209 | late_initcall(load_system_certificate_list); | |
210 | ||
211 | #ifdef CONFIG_SYSTEM_DATA_VERIFICATION | |
212 | ||
213 | /** | |
214 | * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data. | |
215 | * @data: The data to be verified (NULL if expecting internal data). | |
216 | * @len: Size of @data. | |
217 | * @pkcs7: The PKCS#7 message that is the signature. | |
218 | * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, | |
219 | * (void *)1UL for all trusted keys). | |
220 | * @usage: The use to which the key is being put. | |
221 | * @view_content: Callback to gain access to content. | |
222 | * @ctx: Context for callback. | |
223 | */ | |
224 | int verify_pkcs7_message_sig(const void *data, size_t len, | |
225 | struct pkcs7_message *pkcs7, | |
226 | struct key *trusted_keys, | |
227 | enum key_being_used_for usage, | |
228 | int (*view_content)(void *ctx, | |
229 | const void *data, size_t len, | |
230 | size_t asn1hdrlen), | |
231 | void *ctx) | |
232 | { | |
233 | int ret; | |
234 | ||
235 | /* The data should be detached - so we need to supply it. */ | |
236 | if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { | |
237 | pr_err("PKCS#7 signature with non-detached data\n"); | |
238 | ret = -EBADMSG; | |
239 | goto error; | |
240 | } | |
241 | ||
242 | ret = pkcs7_verify(pkcs7, usage); | |
243 | if (ret < 0) | |
244 | goto error; | |
245 | ||
246 | if (!trusted_keys) { | |
247 | trusted_keys = builtin_trusted_keys; | |
248 | } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { | |
249 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
250 | trusted_keys = secondary_trusted_keys; | |
251 | #else | |
252 | trusted_keys = builtin_trusted_keys; | |
253 | #endif | |
254 | } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) { | |
255 | #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING | |
256 | trusted_keys = platform_trusted_keys; | |
257 | #else | |
258 | trusted_keys = NULL; | |
259 | #endif | |
260 | if (!trusted_keys) { | |
261 | ret = -ENOKEY; | |
262 | pr_devel("PKCS#7 platform keyring is not available\n"); | |
263 | goto error; | |
264 | } | |
265 | ||
266 | ret = is_key_on_revocation_list(pkcs7); | |
267 | if (ret != -ENOKEY) { | |
268 | pr_devel("PKCS#7 platform key is on revocation list\n"); | |
269 | goto error; | |
270 | } | |
271 | } | |
272 | ret = pkcs7_validate_trust(pkcs7, trusted_keys); | |
273 | if (ret < 0) { | |
274 | if (ret == -ENOKEY) | |
275 | pr_devel("PKCS#7 signature not signed with a trusted key\n"); | |
276 | goto error; | |
277 | } | |
278 | ||
279 | if (view_content) { | |
280 | size_t asn1hdrlen; | |
281 | ||
282 | ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); | |
283 | if (ret < 0) { | |
284 | if (ret == -ENODATA) | |
285 | pr_devel("PKCS#7 message does not contain data\n"); | |
286 | goto error; | |
287 | } | |
288 | ||
289 | ret = view_content(ctx, data, len, asn1hdrlen); | |
290 | } | |
291 | ||
292 | error: | |
293 | pr_devel("<==%s() = %d\n", __func__, ret); | |
294 | return ret; | |
295 | } | |
296 | ||
297 | /** | |
298 | * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. | |
299 | * @data: The data to be verified (NULL if expecting internal data). | |
300 | * @len: Size of @data. | |
301 | * @raw_pkcs7: The PKCS#7 message that is the signature. | |
302 | * @pkcs7_len: The size of @raw_pkcs7. | |
303 | * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, | |
304 | * (void *)1UL for all trusted keys). | |
305 | * @usage: The use to which the key is being put. | |
306 | * @view_content: Callback to gain access to content. | |
307 | * @ctx: Context for callback. | |
308 | */ | |
309 | int verify_pkcs7_signature(const void *data, size_t len, | |
310 | const void *raw_pkcs7, size_t pkcs7_len, | |
311 | struct key *trusted_keys, | |
312 | enum key_being_used_for usage, | |
313 | int (*view_content)(void *ctx, | |
314 | const void *data, size_t len, | |
315 | size_t asn1hdrlen), | |
316 | void *ctx) | |
317 | { | |
318 | struct pkcs7_message *pkcs7; | |
319 | int ret; | |
320 | ||
321 | pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); | |
322 | if (IS_ERR(pkcs7)) | |
323 | return PTR_ERR(pkcs7); | |
324 | ||
325 | ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage, | |
326 | view_content, ctx); | |
327 | ||
328 | pkcs7_free_message(pkcs7); | |
329 | pr_devel("<==%s() = %d\n", __func__, ret); | |
330 | return ret; | |
331 | } | |
332 | EXPORT_SYMBOL_GPL(verify_pkcs7_signature); | |
333 | ||
334 | #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ | |
335 | ||
336 | #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING | |
337 | void __init set_platform_trusted_keys(struct key *keyring) | |
338 | { | |
339 | platform_trusted_keys = keyring; | |
340 | } | |
341 | #endif |