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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 <keys/asymmetric-type.h>
19#include <keys/system_keyring.h>
20#include <crypto/pkcs7.h>
21
22static struct key *builtin_trusted_keys;
23#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
24static struct key *secondary_trusted_keys;
25#endif
26
27extern __initconst const u8 system_certificate_list[];
28extern __initconst const unsigned long system_certificate_list_size;
29
30/**
31 * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA
32 *
33 * Restrict the addition of keys into a keyring based on the key-to-be-added
34 * being vouched for by a key in the built in system keyring.
35 */
36int restrict_link_by_builtin_trusted(struct key *dest_keyring,
37 const struct key_type *type,
38 const union key_payload *payload,
39 struct key *restriction_key)
40{
41 return restrict_link_by_signature(dest_keyring, type, payload,
42 builtin_trusted_keys);
43}
44
45#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
46/**
47 * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring
48 * addition by both builtin and secondary keyrings
49 *
50 * Restrict the addition of keys into a keyring based on the key-to-be-added
51 * being vouched for by a key in either the built-in or the secondary system
52 * keyrings.
53 */
54int restrict_link_by_builtin_and_secondary_trusted(
55 struct key *dest_keyring,
56 const struct key_type *type,
57 const union key_payload *payload,
58 struct key *restrict_key)
59{
60 /* If we have a secondary trusted keyring, then that contains a link
61 * through to the builtin keyring and the search will follow that link.
62 */
63 if (type == &key_type_keyring &&
64 dest_keyring == secondary_trusted_keys &&
65 payload == &builtin_trusted_keys->payload)
66 /* Allow the builtin keyring to be added to the secondary */
67 return 0;
68
69 return restrict_link_by_signature(dest_keyring, type, payload,
70 secondary_trusted_keys);
71}
72
73/**
74 * Allocate a struct key_restriction for the "builtin and secondary trust"
75 * keyring. Only for use in system_trusted_keyring_init().
76 */
77static __init struct key_restriction *get_builtin_and_secondary_restriction(void)
78{
79 struct key_restriction *restriction;
80
81 restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
82
83 if (!restriction)
84 panic("Can't allocate secondary trusted keyring restriction\n");
85
86 restriction->check = restrict_link_by_builtin_and_secondary_trusted;
87
88 return restriction;
89}
90#endif
91
92/*
93 * Create the trusted keyrings
94 */
95static __init int system_trusted_keyring_init(void)
96{
97 pr_notice("Initialise system trusted keyrings\n");
98
99 builtin_trusted_keys =
100 keyring_alloc(".builtin_trusted_keys",
101 KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
102 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
103 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
104 KEY_ALLOC_NOT_IN_QUOTA,
105 NULL, NULL);
106 if (IS_ERR(builtin_trusted_keys))
107 panic("Can't allocate builtin trusted keyring\n");
108
109#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
110 secondary_trusted_keys =
111 keyring_alloc(".secondary_trusted_keys",
112 KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
113 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
114 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH |
115 KEY_USR_WRITE),
116 KEY_ALLOC_NOT_IN_QUOTA,
117 get_builtin_and_secondary_restriction(),
118 NULL);
119 if (IS_ERR(secondary_trusted_keys))
120 panic("Can't allocate secondary trusted keyring\n");
121
122 if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0)
123 panic("Can't link trusted keyrings\n");
124#endif
125
126 return 0;
127}
128
129/*
130 * Must be initialised before we try and load the keys into the keyring.
131 */
132device_initcall(system_trusted_keyring_init);
133
134/*
135 * Load the compiled-in list of X.509 certificates.
136 */
137static __init int load_system_certificate_list(void)
138{
139 key_ref_t key;
140 const u8 *p, *end;
141 size_t plen;
142
143 pr_notice("Loading compiled-in X.509 certificates\n");
144
145 p = system_certificate_list;
146 end = p + system_certificate_list_size;
147 while (p < end) {
148 /* Each cert begins with an ASN.1 SEQUENCE tag and must be more
149 * than 256 bytes in size.
150 */
151 if (end - p < 4)
152 goto dodgy_cert;
153 if (p[0] != 0x30 &&
154 p[1] != 0x82)
155 goto dodgy_cert;
156 plen = (p[2] << 8) | p[3];
157 plen += 4;
158 if (plen > end - p)
159 goto dodgy_cert;
160
161 key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1),
162 "asymmetric",
163 NULL,
164 p,
165 plen,
166 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
167 KEY_USR_VIEW | KEY_USR_READ),
168 KEY_ALLOC_NOT_IN_QUOTA |
169 KEY_ALLOC_BUILT_IN |
170 KEY_ALLOC_BYPASS_RESTRICTION);
171 if (IS_ERR(key)) {
172 pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
173 PTR_ERR(key));
174 } else {
175 pr_notice("Loaded X.509 cert '%s'\n",
176 key_ref_to_ptr(key)->description);
177 key_ref_put(key);
178 }
179 p += plen;
180 }
181
182 return 0;
183
184dodgy_cert:
185 pr_err("Problem parsing in-kernel X.509 certificate list\n");
186 return 0;
187}
188late_initcall(load_system_certificate_list);
189
190#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
191
192/**
193 * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
194 * @data: The data to be verified (NULL if expecting internal data).
195 * @len: Size of @data.
196 * @raw_pkcs7: The PKCS#7 message that is the signature.
197 * @pkcs7_len: The size of @raw_pkcs7.
198 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
199 * (void *)1UL for all trusted keys).
200 * @usage: The use to which the key is being put.
201 * @view_content: Callback to gain access to content.
202 * @ctx: Context for callback.
203 */
204int verify_pkcs7_signature(const void *data, size_t len,
205 const void *raw_pkcs7, size_t pkcs7_len,
206 struct key *trusted_keys,
207 enum key_being_used_for usage,
208 int (*view_content)(void *ctx,
209 const void *data, size_t len,
210 size_t asn1hdrlen),
211 void *ctx)
212{
213 struct pkcs7_message *pkcs7;
214 int ret;
215
216 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
217 if (IS_ERR(pkcs7))
218 return PTR_ERR(pkcs7);
219
220 /* The data should be detached - so we need to supply it. */
221 if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
222 pr_err("PKCS#7 signature with non-detached data\n");
223 ret = -EBADMSG;
224 goto error;
225 }
226
227 ret = pkcs7_verify(pkcs7, usage);
228 if (ret < 0)
229 goto error;
230
231 if (!trusted_keys) {
232 trusted_keys = builtin_trusted_keys;
233 } else if (trusted_keys == (void *)1UL) {
234#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
235 trusted_keys = secondary_trusted_keys;
236#else
237 trusted_keys = builtin_trusted_keys;
238#endif
239 }
240 ret = pkcs7_validate_trust(pkcs7, trusted_keys);
241 if (ret < 0) {
242 if (ret == -ENOKEY)
243 pr_err("PKCS#7 signature not signed with a trusted key\n");
244 goto error;
245 }
246
247 if (view_content) {
248 size_t asn1hdrlen;
249
250 ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);
251 if (ret < 0) {
252 if (ret == -ENODATA)
253 pr_devel("PKCS#7 message does not contain data\n");
254 goto error;
255 }
256
257 ret = view_content(ctx, data, len, asn1hdrlen);
258 }
259
260error:
261 pkcs7_free_message(pkcs7);
262 pr_devel("<==%s() = %d\n", __func__, ret);
263 return ret;
264}
265EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
266
267#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
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