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 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 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 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 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(sizeof(struct key_restriction), GFP_KERNEL);
144
145 if (!restriction)
146 panic("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(make_key_ref(secondary_trusted_keys, 1),
173 "asymmetric",
174 NULL, data, len, perm,
175 KEY_ALLOC_NOT_IN_QUOTA);
176 if (IS_ERR(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);
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(secondary_trusted_keys, machine_trusted_keys) < 0)
192 panic("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(".builtin_trusted_keys",
232 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(),
233 ((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(system_certificate_list,
273 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(p, size, 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, 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, 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, &len, &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(raw_pkcs7, pkcs7_len);
409 if (IS_ERR(pkcs7))
410 return PTR_ERR(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
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