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_by_builtin_trusted - Restrict keyring addition by built-in CA |
37 | * @dest_keyring: Keyring being linked to. |
38 | * @type: The type of key being added. |
39 | * @payload: The payload of the new key. |
40 | * @restriction_key: A ring of keys that can be used to vouch for the new cert. |
41 | * |
42 | * Restrict the addition of keys into a keyring based on the key-to-be-added |
43 | * being vouched for by a key in the built in system keyring. |
44 | */ |
45 | int restrict_link_by_builtin_trusted(struct key *dest_keyring, |
46 | const struct key_type *type, |
47 | const union key_payload *payload, |
48 | struct key *restriction_key) |
49 | { |
50 | return restrict_link_by_signature(dest_keyring, type, payload, |
51 | trust_keyring: builtin_trusted_keys); |
52 | } |
53 | |
54 | /** |
55 | * restrict_link_by_digsig_builtin - Restrict digitalSignature key additions by the built-in keyring |
56 | * @dest_keyring: Keyring being linked to. |
57 | * @type: The type of key being added. |
58 | * @payload: The payload of the new key. |
59 | * @restriction_key: A ring of keys that can be used to vouch for the new cert. |
60 | * |
61 | * Restrict the addition of keys into a keyring based on the key-to-be-added |
62 | * being vouched for by a key in the built in system keyring. The new key |
63 | * must have the digitalSignature usage field set. |
64 | */ |
65 | int restrict_link_by_digsig_builtin(struct key *dest_keyring, |
66 | const struct key_type *type, |
67 | const union key_payload *payload, |
68 | struct key *restriction_key) |
69 | { |
70 | return restrict_link_by_digsig(dest_keyring, type, payload, |
71 | trust_keyring: builtin_trusted_keys); |
72 | } |
73 | |
74 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
75 | /** |
76 | * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring |
77 | * addition by both built-in and secondary keyrings. |
78 | * @dest_keyring: Keyring being linked to. |
79 | * @type: The type of key being added. |
80 | * @payload: The payload of the new key. |
81 | * @restrict_key: A ring of keys that can be used to vouch for the new cert. |
82 | * |
83 | * Restrict the addition of keys into a keyring based on the key-to-be-added |
84 | * being vouched for by a key in either the built-in or the secondary system |
85 | * keyrings. |
86 | */ |
87 | int restrict_link_by_builtin_and_secondary_trusted( |
88 | struct key *dest_keyring, |
89 | const struct key_type *type, |
90 | const union key_payload *payload, |
91 | struct key *restrict_key) |
92 | { |
93 | /* If we have a secondary trusted keyring, then that contains a link |
94 | * through to the builtin keyring and the search will follow that link. |
95 | */ |
96 | if (type == &key_type_keyring && |
97 | dest_keyring == secondary_trusted_keys && |
98 | payload == &builtin_trusted_keys->payload) |
99 | /* Allow the builtin keyring to be added to the secondary */ |
100 | return 0; |
101 | |
102 | return restrict_link_by_signature(dest_keyring, type, payload, |
103 | trust_keyring: secondary_trusted_keys); |
104 | } |
105 | |
106 | /** |
107 | * restrict_link_by_digsig_builtin_and_secondary - Restrict by digitalSignature. |
108 | * @dest_keyring: Keyring being linked to. |
109 | * @type: The type of key being added. |
110 | * @payload: The payload of the new key. |
111 | * @restrict_key: A ring of keys that can be used to vouch for the new cert. |
112 | * |
113 | * Restrict the addition of keys into a keyring based on the key-to-be-added |
114 | * being vouched for by a key in either the built-in or the secondary system |
115 | * keyrings. The new key must have the digitalSignature usage field set. |
116 | */ |
117 | int restrict_link_by_digsig_builtin_and_secondary(struct key *dest_keyring, |
118 | const struct key_type *type, |
119 | const union key_payload *payload, |
120 | struct key *restrict_key) |
121 | { |
122 | /* If we have a secondary trusted keyring, then that contains a link |
123 | * through to the builtin keyring and the search will follow that link. |
124 | */ |
125 | if (type == &key_type_keyring && |
126 | dest_keyring == secondary_trusted_keys && |
127 | payload == &builtin_trusted_keys->payload) |
128 | /* Allow the builtin keyring to be added to the secondary */ |
129 | return 0; |
130 | |
131 | return restrict_link_by_digsig(dest_keyring, type, payload, |
132 | trust_keyring: secondary_trusted_keys); |
133 | } |
134 | |
135 | /* |
136 | * Allocate a struct key_restriction for the "builtin and secondary trust" |
137 | * keyring. Only for use in system_trusted_keyring_init(). |
138 | */ |
139 | static __init struct key_restriction *get_builtin_and_secondary_restriction(void) |
140 | { |
141 | struct key_restriction *restriction; |
142 | |
143 | restriction = kzalloc(size: sizeof(struct key_restriction), GFP_KERNEL); |
144 | |
145 | if (!restriction) |
146 | panic(fmt: "Can't allocate secondary trusted keyring restriction\n" ); |
147 | |
148 | if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING)) |
149 | restriction->check = restrict_link_by_builtin_secondary_and_machine; |
150 | else |
151 | restriction->check = restrict_link_by_builtin_and_secondary_trusted; |
152 | |
153 | return restriction; |
154 | } |
155 | |
156 | /** |
157 | * add_to_secondary_keyring - Add to secondary keyring. |
158 | * @source: Source of key |
159 | * @data: The blob holding the key |
160 | * @len: The length of the data blob |
161 | * |
162 | * Add a key to the secondary keyring. The key must be vouched for by a key in the builtin, |
163 | * machine or secondary keyring itself. |
164 | */ |
165 | void __init add_to_secondary_keyring(const char *source, const void *data, size_t len) |
166 | { |
167 | key_ref_t key; |
168 | key_perm_t perm; |
169 | |
170 | perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW; |
171 | |
172 | key = key_create_or_update(keyring: make_key_ref(key: secondary_trusted_keys, possession: 1), |
173 | type: "asymmetric" , |
174 | NULL, payload: data, plen: len, perm, |
175 | KEY_ALLOC_NOT_IN_QUOTA); |
176 | if (IS_ERR(ptr: key)) { |
177 | pr_err("Problem loading X.509 certificate from %s to secondary keyring %ld\n" , |
178 | source, PTR_ERR(key)); |
179 | return; |
180 | } |
181 | |
182 | pr_notice("Loaded X.509 cert '%s'\n" , key_ref_to_ptr(key)->description); |
183 | key_ref_put(key_ref: key); |
184 | } |
185 | #endif |
186 | #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING |
187 | void __init set_machine_trusted_keys(struct key *keyring) |
188 | { |
189 | machine_trusted_keys = keyring; |
190 | |
191 | if (key_link(keyring: secondary_trusted_keys, key: machine_trusted_keys) < 0) |
192 | panic(fmt: "Can't link (machine) trusted keyrings\n" ); |
193 | } |
194 | |
195 | /** |
196 | * restrict_link_by_builtin_secondary_and_machine - Restrict keyring addition. |
197 | * @dest_keyring: Keyring being linked to. |
198 | * @type: The type of key being added. |
199 | * @payload: The payload of the new key. |
200 | * @restrict_key: A ring of keys that can be used to vouch for the new cert. |
201 | * |
202 | * Restrict the addition of keys into a keyring based on the key-to-be-added |
203 | * being vouched for by a key in either the built-in, the secondary, or |
204 | * the machine keyrings. |
205 | */ |
206 | int restrict_link_by_builtin_secondary_and_machine( |
207 | struct key *dest_keyring, |
208 | const struct key_type *type, |
209 | const union key_payload *payload, |
210 | struct key *restrict_key) |
211 | { |
212 | if (machine_trusted_keys && type == &key_type_keyring && |
213 | dest_keyring == secondary_trusted_keys && |
214 | payload == &machine_trusted_keys->payload) |
215 | /* Allow the machine keyring to be added to the secondary */ |
216 | return 0; |
217 | |
218 | return restrict_link_by_builtin_and_secondary_trusted(dest_keyring, type, |
219 | payload, restrict_key); |
220 | } |
221 | #endif |
222 | |
223 | /* |
224 | * Create the trusted keyrings |
225 | */ |
226 | static __init int system_trusted_keyring_init(void) |
227 | { |
228 | pr_notice("Initialise system trusted keyrings\n" ); |
229 | |
230 | builtin_trusted_keys = |
231 | keyring_alloc(description: ".builtin_trusted_keys" , |
232 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), |
233 | perm: ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
234 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), |
235 | KEY_ALLOC_NOT_IN_QUOTA, |
236 | NULL, NULL); |
237 | if (IS_ERR(builtin_trusted_keys)) |
238 | panic("Can't allocate builtin trusted keyring\n" ); |
239 | |
240 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
241 | secondary_trusted_keys = |
242 | keyring_alloc(".secondary_trusted_keys" , |
243 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), |
244 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
245 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | |
246 | KEY_USR_WRITE), |
247 | KEY_ALLOC_NOT_IN_QUOTA, |
248 | get_builtin_and_secondary_restriction(), |
249 | NULL); |
250 | if (IS_ERR(secondary_trusted_keys)) |
251 | panic("Can't allocate secondary trusted keyring\n" ); |
252 | |
253 | if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) |
254 | panic("Can't link trusted keyrings\n" ); |
255 | #endif |
256 | |
257 | return 0; |
258 | } |
259 | |
260 | /* |
261 | * Must be initialised before we try and load the keys into the keyring. |
262 | */ |
263 | device_initcall(system_trusted_keyring_init); |
264 | |
265 | __init int load_module_cert(struct key *keyring) |
266 | { |
267 | if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG)) |
268 | return 0; |
269 | |
270 | pr_notice("Loading compiled-in module X.509 certificates\n" ); |
271 | |
272 | return x509_load_certificate_list(cert_list: system_certificate_list, |
273 | list_size: module_cert_size, keyring); |
274 | } |
275 | |
276 | /* |
277 | * Load the compiled-in list of X.509 certificates. |
278 | */ |
279 | static __init int load_system_certificate_list(void) |
280 | { |
281 | const u8 *p; |
282 | unsigned long size; |
283 | |
284 | pr_notice("Loading compiled-in X.509 certificates\n" ); |
285 | |
286 | #ifdef CONFIG_MODULE_SIG |
287 | p = system_certificate_list; |
288 | size = system_certificate_list_size; |
289 | #else |
290 | p = system_certificate_list + module_cert_size; |
291 | size = system_certificate_list_size - module_cert_size; |
292 | #endif |
293 | |
294 | return x509_load_certificate_list(cert_list: p, list_size: size, keyring: builtin_trusted_keys); |
295 | } |
296 | late_initcall(load_system_certificate_list); |
297 | |
298 | #ifdef CONFIG_SYSTEM_DATA_VERIFICATION |
299 | |
300 | /** |
301 | * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data. |
302 | * @data: The data to be verified (NULL if expecting internal data). |
303 | * @len: Size of @data. |
304 | * @pkcs7: The PKCS#7 message that is the signature. |
305 | * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, |
306 | * (void *)1UL for all trusted keys). |
307 | * @usage: The use to which the key is being put. |
308 | * @view_content: Callback to gain access to content. |
309 | * @ctx: Context for callback. |
310 | */ |
311 | int verify_pkcs7_message_sig(const void *data, size_t len, |
312 | struct pkcs7_message *pkcs7, |
313 | struct key *trusted_keys, |
314 | enum key_being_used_for usage, |
315 | int (*view_content)(void *ctx, |
316 | const void *data, size_t len, |
317 | size_t asn1hdrlen), |
318 | void *ctx) |
319 | { |
320 | int ret; |
321 | |
322 | /* The data should be detached - so we need to supply it. */ |
323 | if (data && pkcs7_supply_detached_data(pkcs7, data, datalen: len) < 0) { |
324 | pr_err("PKCS#7 signature with non-detached data\n" ); |
325 | ret = -EBADMSG; |
326 | goto error; |
327 | } |
328 | |
329 | ret = pkcs7_verify(pkcs7, usage); |
330 | if (ret < 0) |
331 | goto error; |
332 | |
333 | ret = is_key_on_revocation_list(pkcs7); |
334 | if (ret != -ENOKEY) { |
335 | pr_devel("PKCS#7 key is on revocation list\n" ); |
336 | goto error; |
337 | } |
338 | |
339 | if (!trusted_keys) { |
340 | trusted_keys = builtin_trusted_keys; |
341 | } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { |
342 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
343 | trusted_keys = secondary_trusted_keys; |
344 | #else |
345 | trusted_keys = builtin_trusted_keys; |
346 | #endif |
347 | } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) { |
348 | #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING |
349 | trusted_keys = platform_trusted_keys; |
350 | #else |
351 | trusted_keys = NULL; |
352 | #endif |
353 | if (!trusted_keys) { |
354 | ret = -ENOKEY; |
355 | pr_devel("PKCS#7 platform keyring is not available\n" ); |
356 | goto error; |
357 | } |
358 | } |
359 | ret = pkcs7_validate_trust(pkcs7, trust_keyring: trusted_keys); |
360 | if (ret < 0) { |
361 | if (ret == -ENOKEY) |
362 | pr_devel("PKCS#7 signature not signed with a trusted key\n" ); |
363 | goto error; |
364 | } |
365 | |
366 | if (view_content) { |
367 | size_t asn1hdrlen; |
368 | |
369 | ret = pkcs7_get_content_data(pkcs7, data: &data, datalen: &len, headerlen: &asn1hdrlen); |
370 | if (ret < 0) { |
371 | if (ret == -ENODATA) |
372 | pr_devel("PKCS#7 message does not contain data\n" ); |
373 | goto error; |
374 | } |
375 | |
376 | ret = view_content(ctx, data, len, asn1hdrlen); |
377 | } |
378 | |
379 | error: |
380 | pr_devel("<==%s() = %d\n" , __func__, ret); |
381 | return ret; |
382 | } |
383 | |
384 | /** |
385 | * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. |
386 | * @data: The data to be verified (NULL if expecting internal data). |
387 | * @len: Size of @data. |
388 | * @raw_pkcs7: The PKCS#7 message that is the signature. |
389 | * @pkcs7_len: The size of @raw_pkcs7. |
390 | * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, |
391 | * (void *)1UL for all trusted keys). |
392 | * @usage: The use to which the key is being put. |
393 | * @view_content: Callback to gain access to content. |
394 | * @ctx: Context for callback. |
395 | */ |
396 | int verify_pkcs7_signature(const void *data, size_t len, |
397 | const void *raw_pkcs7, size_t pkcs7_len, |
398 | struct key *trusted_keys, |
399 | enum key_being_used_for usage, |
400 | int (*view_content)(void *ctx, |
401 | const void *data, size_t len, |
402 | size_t asn1hdrlen), |
403 | void *ctx) |
404 | { |
405 | struct pkcs7_message *pkcs7; |
406 | int ret; |
407 | |
408 | pkcs7 = pkcs7_parse_message(data: raw_pkcs7, datalen: pkcs7_len); |
409 | if (IS_ERR(ptr: pkcs7)) |
410 | return PTR_ERR(ptr: pkcs7); |
411 | |
412 | ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage, |
413 | view_content, ctx); |
414 | |
415 | pkcs7_free_message(pkcs7); |
416 | pr_devel("<==%s() = %d\n" , __func__, ret); |
417 | return ret; |
418 | } |
419 | EXPORT_SYMBOL_GPL(verify_pkcs7_signature); |
420 | |
421 | #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ |
422 | |
423 | #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING |
424 | void __init set_platform_trusted_keys(struct key *keyring) |
425 | { |
426 | platform_trusted_keys = keyring; |
427 | } |
428 | #endif |
429 | |