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b4d0d230 1// SPDX-License-Identifier: GPL-2.0-or-later
b56e5a17
DH
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)
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DH
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>
2b6aa412 13#include <linux/slab.h>
817aef26 14#include <linux/verification.h>
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DH
15#include <keys/asymmetric-type.h>
16#include <keys/system_keyring.h>
091f6e26 17#include <crypto/pkcs7.h>
b56e5a17 18
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DH
19static struct key *builtin_trusted_keys;
20#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
21static struct key *secondary_trusted_keys;
22#endif
219a3e86
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23#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
24static struct key *platform_trusted_keys;
25#endif
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26
27extern __initconst const u8 system_certificate_list[];
62226983 28extern __initconst const unsigned long system_certificate_list_size;
b56e5a17 29
a511e1af 30/**
d3bfe841 31 * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA
a511e1af
DH
32 *
33 * Restrict the addition of keys into a keyring based on the key-to-be-added
d3bfe841 34 * being vouched for by a key in the built in system keyring.
a511e1af 35 */
aaf66c88 36int restrict_link_by_builtin_trusted(struct key *dest_keyring,
a511e1af 37 const struct key_type *type,
aaf66c88
MM
38 const union key_payload *payload,
39 struct key *restriction_key)
a511e1af 40{
aaf66c88
MM
41 return restrict_link_by_signature(dest_keyring, type, payload,
42 builtin_trusted_keys);
a511e1af
DH
43}
44
d3bfe841
DH
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(
aaf66c88 55 struct key *dest_keyring,
d3bfe841 56 const struct key_type *type,
aaf66c88
MM
57 const union key_payload *payload,
58 struct key *restrict_key)
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DH
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 &&
aaf66c88 64 dest_keyring == secondary_trusted_keys &&
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65 payload == &builtin_trusted_keys->payload)
66 /* Allow the builtin keyring to be added to the secondary */
67 return 0;
68
aaf66c88
MM
69 return restrict_link_by_signature(dest_keyring, type, payload,
70 secondary_trusted_keys);
d3bfe841 71}
2b6aa412
MM
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}
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DH
90#endif
91
b56e5a17 92/*
d3bfe841 93 * Create the trusted keyrings
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DH
94 */
95static __init int system_trusted_keyring_init(void)
96{
d3bfe841 97 pr_notice("Initialise system trusted keyrings\n");
b56e5a17 98
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DH
99 builtin_trusted_keys =
100 keyring_alloc(".builtin_trusted_keys",
b56e5a17 101 KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
028db3e2
LT
102 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
103 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
104 KEY_ALLOC_NOT_IN_QUOTA,
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DH
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(),
028db3e2
LT
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,
2b6aa412 117 get_builtin_and_secondary_restriction(),
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DH
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
b56e5a17
DH
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
b56e5a17 145 p = system_certificate_list;
62226983 146 end = p + system_certificate_list_size;
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DH
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
d3bfe841 161 key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1),
b56e5a17
DH
162 "asymmetric",
163 NULL,
164 p,
165 plen,
028db3e2
LT
166 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
167 KEY_USR_VIEW | KEY_USR_READ),
008643b8 168 KEY_ALLOC_NOT_IN_QUOTA |
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169 KEY_ALLOC_BUILT_IN |
170 KEY_ALLOC_BYPASS_RESTRICTION);
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171 if (IS_ERR(key)) {
172 pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
173 PTR_ERR(key));
067eb599 174 WARN_ON_ONCE(1);
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DH
175 } else {
176 pr_notice("Loaded X.509 cert '%s'\n",
177 key_ref_to_ptr(key)->description);
178 key_ref_put(key);
179 }
180 p += plen;
181 }
182
183 return 0;
184
185dodgy_cert:
186 pr_err("Problem parsing in-kernel X.509 certificate list\n");
187 return 0;
188}
189late_initcall(load_system_certificate_list);
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DH
190
191#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
192
193/**
2a7bf671 194 * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data.
e68503bd 195 * @data: The data to be verified (NULL if expecting internal data).
091f6e26 196 * @len: Size of @data.
2a7bf671 197 * @pkcs7: The PKCS#7 message that is the signature.
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DH
198 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
199 * (void *)1UL for all trusted keys).
99db4435 200 * @usage: The use to which the key is being put.
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201 * @view_content: Callback to gain access to content.
202 * @ctx: Context for callback.
091f6e26 203 */
2a7bf671
TJB
204int verify_pkcs7_message_sig(const void *data, size_t len,
205 struct pkcs7_message *pkcs7,
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)
091f6e26 212{
091f6e26
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213 int ret;
214
091f6e26 215 /* The data should be detached - so we need to supply it. */
e68503bd 216 if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
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217 pr_err("PKCS#7 signature with non-detached data\n");
218 ret = -EBADMSG;
219 goto error;
220 }
221
99db4435 222 ret = pkcs7_verify(pkcs7, usage);
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223 if (ret < 0)
224 goto error;
225
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DH
226 if (!trusted_keys) {
227 trusted_keys = builtin_trusted_keys;
817aef26 228 } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) {
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DH
229#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
230 trusted_keys = secondary_trusted_keys;
231#else
232 trusted_keys = builtin_trusted_keys;
233#endif
278311e4
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234 } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) {
235#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
236 trusted_keys = platform_trusted_keys;
237#else
238 trusted_keys = NULL;
239#endif
240 if (!trusted_keys) {
241 ret = -ENOKEY;
242 pr_devel("PKCS#7 platform keyring is not available\n");
243 goto error;
244 }
d3bfe841 245 }
bda850cd
DH
246 ret = pkcs7_validate_trust(pkcs7, trusted_keys);
247 if (ret < 0) {
248 if (ret == -ENOKEY)
278311e4 249 pr_devel("PKCS#7 signature not signed with a trusted key\n");
e68503bd
DH
250 goto error;
251 }
252
253 if (view_content) {
254 size_t asn1hdrlen;
255
256 ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);
257 if (ret < 0) {
258 if (ret == -ENODATA)
259 pr_devel("PKCS#7 message does not contain data\n");
260 goto error;
261 }
262
263 ret = view_content(ctx, data, len, asn1hdrlen);
091f6e26
DH
264 }
265
266error:
2a7bf671
TJB
267 pr_devel("<==%s() = %d\n", __func__, ret);
268 return ret;
269}
270
271/**
272 * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
273 * @data: The data to be verified (NULL if expecting internal data).
274 * @len: Size of @data.
275 * @raw_pkcs7: The PKCS#7 message that is the signature.
276 * @pkcs7_len: The size of @raw_pkcs7.
277 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
278 * (void *)1UL for all trusted keys).
279 * @usage: The use to which the key is being put.
280 * @view_content: Callback to gain access to content.
281 * @ctx: Context for callback.
282 */
283int verify_pkcs7_signature(const void *data, size_t len,
284 const void *raw_pkcs7, size_t pkcs7_len,
285 struct key *trusted_keys,
286 enum key_being_used_for usage,
287 int (*view_content)(void *ctx,
288 const void *data, size_t len,
289 size_t asn1hdrlen),
290 void *ctx)
291{
292 struct pkcs7_message *pkcs7;
293 int ret;
294
295 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
296 if (IS_ERR(pkcs7))
297 return PTR_ERR(pkcs7);
298
299 ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage,
300 view_content, ctx);
301
091f6e26
DH
302 pkcs7_free_message(pkcs7);
303 pr_devel("<==%s() = %d\n", __func__, ret);
304 return ret;
305}
e68503bd 306EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
091f6e26
DH
307
308#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
219a3e86
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309
310#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
311void __init set_platform_trusted_keys(struct key *keyring)
312{
313 platform_trusted_keys = keyring;
314}
315#endif