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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) | |
b56e5a17 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> |
b56e5a17 DH |
15 | #include <keys/asymmetric-type.h> |
16 | #include <keys/system_keyring.h> | |
091f6e26 | 17 | #include <crypto/pkcs7.h> |
b56e5a17 | 18 | |
d3bfe841 DH |
19 | static struct key *builtin_trusted_keys; |
20 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
21 | static struct key *secondary_trusted_keys; | |
22 | #endif | |
219a3e86 KS |
23 | #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING |
24 | static struct key *platform_trusted_keys; | |
25 | #endif | |
b56e5a17 DH |
26 | |
27 | extern __initconst const u8 system_certificate_list[]; | |
62226983 | 28 | extern __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 | 36 | int 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 | */ | |
54 | int 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) | |
d3bfe841 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 && |
d3bfe841 DH |
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 | */ | |
77 | static __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 | } | |
d3bfe841 DH |
90 | #endif |
91 | ||
b56e5a17 | 92 | /* |
d3bfe841 | 93 | * Create the trusted keyrings |
b56e5a17 DH |
94 | */ |
95 | static __init int system_trusted_keyring_init(void) | |
96 | { | |
d3bfe841 | 97 | pr_notice("Initialise system trusted keyrings\n"); |
b56e5a17 | 98 | |
d3bfe841 DH |
99 | builtin_trusted_keys = |
100 | keyring_alloc(".builtin_trusted_keys", | |
b56e5a17 | 101 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), |
2e12256b | 102 | &internal_key_acl, KEY_ALLOC_NOT_IN_QUOTA, |
d3bfe841 DH |
103 | NULL, NULL); |
104 | if (IS_ERR(builtin_trusted_keys)) | |
105 | panic("Can't allocate builtin trusted keyring\n"); | |
106 | ||
107 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING | |
108 | secondary_trusted_keys = | |
109 | keyring_alloc(".secondary_trusted_keys", | |
110 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), | |
2e12256b | 111 | &internal_writable_keyring_acl, KEY_ALLOC_NOT_IN_QUOTA, |
2b6aa412 | 112 | get_builtin_and_secondary_restriction(), |
d3bfe841 DH |
113 | NULL); |
114 | if (IS_ERR(secondary_trusted_keys)) | |
115 | panic("Can't allocate secondary trusted keyring\n"); | |
116 | ||
117 | if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) | |
118 | panic("Can't link trusted keyrings\n"); | |
119 | #endif | |
120 | ||
b56e5a17 DH |
121 | return 0; |
122 | } | |
123 | ||
124 | /* | |
125 | * Must be initialised before we try and load the keys into the keyring. | |
126 | */ | |
127 | device_initcall(system_trusted_keyring_init); | |
128 | ||
129 | /* | |
130 | * Load the compiled-in list of X.509 certificates. | |
131 | */ | |
132 | static __init int load_system_certificate_list(void) | |
133 | { | |
134 | key_ref_t key; | |
135 | const u8 *p, *end; | |
136 | size_t plen; | |
137 | ||
138 | pr_notice("Loading compiled-in X.509 certificates\n"); | |
139 | ||
b56e5a17 | 140 | p = system_certificate_list; |
62226983 | 141 | end = p + system_certificate_list_size; |
b56e5a17 DH |
142 | while (p < end) { |
143 | /* Each cert begins with an ASN.1 SEQUENCE tag and must be more | |
144 | * than 256 bytes in size. | |
145 | */ | |
146 | if (end - p < 4) | |
147 | goto dodgy_cert; | |
148 | if (p[0] != 0x30 && | |
149 | p[1] != 0x82) | |
150 | goto dodgy_cert; | |
151 | plen = (p[2] << 8) | p[3]; | |
152 | plen += 4; | |
153 | if (plen > end - p) | |
154 | goto dodgy_cert; | |
155 | ||
d3bfe841 | 156 | key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1), |
b56e5a17 DH |
157 | "asymmetric", |
158 | NULL, | |
159 | p, | |
160 | plen, | |
2e12256b | 161 | &internal_key_acl, |
008643b8 | 162 | KEY_ALLOC_NOT_IN_QUOTA | |
5ac7eace DH |
163 | KEY_ALLOC_BUILT_IN | |
164 | KEY_ALLOC_BYPASS_RESTRICTION); | |
b56e5a17 DH |
165 | if (IS_ERR(key)) { |
166 | pr_err("Problem loading in-kernel X.509 certificate (%ld)\n", | |
167 | PTR_ERR(key)); | |
168 | } else { | |
169 | pr_notice("Loaded X.509 cert '%s'\n", | |
170 | key_ref_to_ptr(key)->description); | |
171 | key_ref_put(key); | |
172 | } | |
173 | p += plen; | |
174 | } | |
175 | ||
176 | return 0; | |
177 | ||
178 | dodgy_cert: | |
179 | pr_err("Problem parsing in-kernel X.509 certificate list\n"); | |
180 | return 0; | |
181 | } | |
182 | late_initcall(load_system_certificate_list); | |
091f6e26 DH |
183 | |
184 | #ifdef CONFIG_SYSTEM_DATA_VERIFICATION | |
185 | ||
186 | /** | |
e68503bd DH |
187 | * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. |
188 | * @data: The data to be verified (NULL if expecting internal data). | |
091f6e26 DH |
189 | * @len: Size of @data. |
190 | * @raw_pkcs7: The PKCS#7 message that is the signature. | |
191 | * @pkcs7_len: The size of @raw_pkcs7. | |
d3bfe841 DH |
192 | * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, |
193 | * (void *)1UL for all trusted keys). | |
99db4435 | 194 | * @usage: The use to which the key is being put. |
e68503bd DH |
195 | * @view_content: Callback to gain access to content. |
196 | * @ctx: Context for callback. | |
091f6e26 | 197 | */ |
e68503bd DH |
198 | int verify_pkcs7_signature(const void *data, size_t len, |
199 | const void *raw_pkcs7, size_t pkcs7_len, | |
200 | struct key *trusted_keys, | |
e68503bd DH |
201 | enum key_being_used_for usage, |
202 | int (*view_content)(void *ctx, | |
203 | const void *data, size_t len, | |
204 | size_t asn1hdrlen), | |
205 | void *ctx) | |
091f6e26 DH |
206 | { |
207 | struct pkcs7_message *pkcs7; | |
091f6e26 DH |
208 | int ret; |
209 | ||
210 | pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); | |
211 | if (IS_ERR(pkcs7)) | |
212 | return PTR_ERR(pkcs7); | |
213 | ||
214 | /* The data should be detached - so we need to supply it. */ | |
e68503bd | 215 | if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { |
091f6e26 DH |
216 | pr_err("PKCS#7 signature with non-detached data\n"); |
217 | ret = -EBADMSG; | |
218 | goto error; | |
219 | } | |
220 | ||
99db4435 | 221 | ret = pkcs7_verify(pkcs7, usage); |
091f6e26 DH |
222 | if (ret < 0) |
223 | goto error; | |
224 | ||
d3bfe841 DH |
225 | if (!trusted_keys) { |
226 | trusted_keys = builtin_trusted_keys; | |
817aef26 | 227 | } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { |
d3bfe841 DH |
228 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
229 | trusted_keys = secondary_trusted_keys; | |
230 | #else | |
231 | trusted_keys = builtin_trusted_keys; | |
232 | #endif | |
278311e4 KS |
233 | } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) { |
234 | #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING | |
235 | trusted_keys = platform_trusted_keys; | |
236 | #else | |
237 | trusted_keys = NULL; | |
238 | #endif | |
239 | if (!trusted_keys) { | |
240 | ret = -ENOKEY; | |
241 | pr_devel("PKCS#7 platform keyring is not available\n"); | |
242 | goto error; | |
243 | } | |
d3bfe841 | 244 | } |
bda850cd DH |
245 | ret = pkcs7_validate_trust(pkcs7, trusted_keys); |
246 | if (ret < 0) { | |
247 | if (ret == -ENOKEY) | |
278311e4 | 248 | pr_devel("PKCS#7 signature not signed with a trusted key\n"); |
e68503bd DH |
249 | goto error; |
250 | } | |
251 | ||
252 | if (view_content) { | |
253 | size_t asn1hdrlen; | |
254 | ||
255 | ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); | |
256 | if (ret < 0) { | |
257 | if (ret == -ENODATA) | |
258 | pr_devel("PKCS#7 message does not contain data\n"); | |
259 | goto error; | |
260 | } | |
261 | ||
262 | ret = view_content(ctx, data, len, asn1hdrlen); | |
091f6e26 DH |
263 | } |
264 | ||
265 | error: | |
266 | pkcs7_free_message(pkcs7); | |
267 | pr_devel("<==%s() = %d\n", __func__, ret); | |
268 | return ret; | |
269 | } | |
e68503bd | 270 | EXPORT_SYMBOL_GPL(verify_pkcs7_signature); |
091f6e26 DH |
271 | |
272 | #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ | |
219a3e86 KS |
273 | |
274 | #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING | |
275 | void __init set_platform_trusted_keys(struct key *keyring) | |
276 | { | |
277 | platform_trusted_keys = keyring; | |
278 | } | |
279 | #endif |