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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
20static struct key *builtin_trusted_keys;
21#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
22static struct key *secondary_trusted_keys;
23#endif
24#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
25static struct key *machine_trusted_keys;
26#endif
27#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
28static struct key *platform_trusted_keys;
29#endif
30
31extern __initconst const u8 system_certificate_list[];
32extern __initconst const unsigned long system_certificate_list_size;
33extern __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 */
41int 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 */
59int 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 */
82static __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
100void __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 */
119int 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 */
139static __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 */
176device_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 */
192static __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}
209late_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 */
224int 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
292error:
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 */
309int 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}
332EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
333
334#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
335
336#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
337void __init set_platform_trusted_keys(struct key *keyring)
338{
339 platform_trusted_keys = keyring;
340}
341#endif