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 <linux/verification.h> |
19 | #include <keys/asymmetric-type.h> |
20 | #include <keys/system_keyring.h> |
21 | #include <crypto/pkcs7.h> |
22 | |
23 | static struct key *builtin_trusted_keys; |
24 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
25 | static struct key *secondary_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 | |
34 | /** |
35 | * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA |
36 | * |
37 | * Restrict the addition of keys into a keyring based on the key-to-be-added |
38 | * being vouched for by a key in the built in system keyring. |
39 | */ |
40 | int restrict_link_by_builtin_trusted(struct key *dest_keyring, |
41 | const struct key_type *type, |
42 | const union key_payload *payload, |
43 | struct key *restriction_key) |
44 | { |
45 | return restrict_link_by_signature(dest_keyring, type, payload, |
46 | builtin_trusted_keys); |
47 | } |
48 | |
49 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
50 | /** |
51 | * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring |
52 | * addition by both builtin and secondary keyrings |
53 | * |
54 | * Restrict the addition of keys into a keyring based on the key-to-be-added |
55 | * being vouched for by a key in either the built-in or the secondary system |
56 | * keyrings. |
57 | */ |
58 | int restrict_link_by_builtin_and_secondary_trusted( |
59 | struct key *dest_keyring, |
60 | const struct key_type *type, |
61 | const union key_payload *payload, |
62 | struct key *restrict_key) |
63 | { |
64 | /* If we have a secondary trusted keyring, then that contains a link |
65 | * through to the builtin keyring and the search will follow that link. |
66 | */ |
67 | if (type == &key_type_keyring && |
68 | dest_keyring == secondary_trusted_keys && |
69 | payload == &builtin_trusted_keys->payload) |
70 | /* Allow the builtin keyring to be added to the secondary */ |
71 | return 0; |
72 | |
73 | return restrict_link_by_signature(dest_keyring, type, payload, |
74 | secondary_trusted_keys); |
75 | } |
76 | |
77 | /** |
78 | * Allocate a struct key_restriction for the "builtin and secondary trust" |
79 | * keyring. Only for use in system_trusted_keyring_init(). |
80 | */ |
81 | static __init struct key_restriction *get_builtin_and_secondary_restriction(void) |
82 | { |
83 | struct key_restriction *restriction; |
84 | |
85 | restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL); |
86 | |
87 | if (!restriction) |
88 | panic("Can't allocate secondary trusted keyring restriction\n" ); |
89 | |
90 | restriction->check = restrict_link_by_builtin_and_secondary_trusted; |
91 | |
92 | return restriction; |
93 | } |
94 | #endif |
95 | |
96 | /* |
97 | * Create the trusted keyrings |
98 | */ |
99 | static __init int system_trusted_keyring_init(void) |
100 | { |
101 | pr_notice("Initialise system trusted keyrings\n" ); |
102 | |
103 | builtin_trusted_keys = |
104 | keyring_alloc(".builtin_trusted_keys" , |
105 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), |
106 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
107 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), |
108 | KEY_ALLOC_NOT_IN_QUOTA, |
109 | NULL, NULL); |
110 | if (IS_ERR(builtin_trusted_keys)) |
111 | panic("Can't allocate builtin trusted keyring\n" ); |
112 | |
113 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
114 | secondary_trusted_keys = |
115 | keyring_alloc(".secondary_trusted_keys" , |
116 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), |
117 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
118 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | |
119 | KEY_USR_WRITE), |
120 | KEY_ALLOC_NOT_IN_QUOTA, |
121 | get_builtin_and_secondary_restriction(), |
122 | NULL); |
123 | if (IS_ERR(secondary_trusted_keys)) |
124 | panic("Can't allocate secondary trusted keyring\n" ); |
125 | |
126 | if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) |
127 | panic("Can't link trusted keyrings\n" ); |
128 | #endif |
129 | |
130 | return 0; |
131 | } |
132 | |
133 | /* |
134 | * Must be initialised before we try and load the keys into the keyring. |
135 | */ |
136 | device_initcall(system_trusted_keyring_init); |
137 | |
138 | /* |
139 | * Load the compiled-in list of X.509 certificates. |
140 | */ |
141 | static __init int load_system_certificate_list(void) |
142 | { |
143 | key_ref_t key; |
144 | const u8 *p, *end; |
145 | size_t plen; |
146 | |
147 | pr_notice("Loading compiled-in X.509 certificates\n" ); |
148 | |
149 | p = system_certificate_list; |
150 | end = p + system_certificate_list_size; |
151 | while (p < end) { |
152 | /* Each cert begins with an ASN.1 SEQUENCE tag and must be more |
153 | * than 256 bytes in size. |
154 | */ |
155 | if (end - p < 4) |
156 | goto dodgy_cert; |
157 | if (p[0] != 0x30 && |
158 | p[1] != 0x82) |
159 | goto dodgy_cert; |
160 | plen = (p[2] << 8) | p[3]; |
161 | plen += 4; |
162 | if (plen > end - p) |
163 | goto dodgy_cert; |
164 | |
165 | key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1), |
166 | "asymmetric" , |
167 | NULL, |
168 | p, |
169 | plen, |
170 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
171 | KEY_USR_VIEW | KEY_USR_READ), |
172 | KEY_ALLOC_NOT_IN_QUOTA | |
173 | KEY_ALLOC_BUILT_IN | |
174 | KEY_ALLOC_BYPASS_RESTRICTION); |
175 | if (IS_ERR(key)) { |
176 | pr_err("Problem loading in-kernel X.509 certificate (%ld)\n" , |
177 | PTR_ERR(key)); |
178 | } else { |
179 | pr_notice("Loaded X.509 cert '%s'\n" , |
180 | key_ref_to_ptr(key)->description); |
181 | key_ref_put(key); |
182 | } |
183 | p += plen; |
184 | } |
185 | |
186 | return 0; |
187 | |
188 | dodgy_cert: |
189 | pr_err("Problem parsing in-kernel X.509 certificate list\n" ); |
190 | return 0; |
191 | } |
192 | late_initcall(load_system_certificate_list); |
193 | |
194 | #ifdef CONFIG_SYSTEM_DATA_VERIFICATION |
195 | |
196 | /** |
197 | * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. |
198 | * @data: The data to be verified (NULL if expecting internal data). |
199 | * @len: Size of @data. |
200 | * @raw_pkcs7: The PKCS#7 message that is the signature. |
201 | * @pkcs7_len: The size of @raw_pkcs7. |
202 | * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, |
203 | * (void *)1UL for all trusted keys). |
204 | * @usage: The use to which the key is being put. |
205 | * @view_content: Callback to gain access to content. |
206 | * @ctx: Context for callback. |
207 | */ |
208 | int verify_pkcs7_signature(const void *data, size_t len, |
209 | const void *raw_pkcs7, size_t pkcs7_len, |
210 | struct key *trusted_keys, |
211 | enum key_being_used_for usage, |
212 | int (*view_content)(void *ctx, |
213 | const void *data, size_t len, |
214 | size_t asn1hdrlen), |
215 | void *ctx) |
216 | { |
217 | struct pkcs7_message *pkcs7; |
218 | int ret; |
219 | |
220 | pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); |
221 | if (IS_ERR(pkcs7)) |
222 | return PTR_ERR(pkcs7); |
223 | |
224 | /* The data should be detached - so we need to supply it. */ |
225 | if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { |
226 | pr_err("PKCS#7 signature with non-detached data\n" ); |
227 | ret = -EBADMSG; |
228 | goto error; |
229 | } |
230 | |
231 | ret = pkcs7_verify(pkcs7, usage); |
232 | if (ret < 0) |
233 | goto error; |
234 | |
235 | if (!trusted_keys) { |
236 | trusted_keys = builtin_trusted_keys; |
237 | } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { |
238 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
239 | trusted_keys = secondary_trusted_keys; |
240 | #else |
241 | trusted_keys = builtin_trusted_keys; |
242 | #endif |
243 | } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) { |
244 | #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING |
245 | trusted_keys = platform_trusted_keys; |
246 | #else |
247 | trusted_keys = NULL; |
248 | #endif |
249 | if (!trusted_keys) { |
250 | ret = -ENOKEY; |
251 | pr_devel("PKCS#7 platform keyring is not available\n" ); |
252 | goto error; |
253 | } |
254 | } |
255 | ret = pkcs7_validate_trust(pkcs7, trusted_keys); |
256 | if (ret < 0) { |
257 | if (ret == -ENOKEY) |
258 | pr_devel("PKCS#7 signature not signed with a trusted key\n" ); |
259 | goto error; |
260 | } |
261 | |
262 | if (view_content) { |
263 | size_t asn1hdrlen; |
264 | |
265 | ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); |
266 | if (ret < 0) { |
267 | if (ret == -ENODATA) |
268 | pr_devel("PKCS#7 message does not contain data\n" ); |
269 | goto error; |
270 | } |
271 | |
272 | ret = view_content(ctx, data, len, asn1hdrlen); |
273 | } |
274 | |
275 | error: |
276 | pkcs7_free_message(pkcs7); |
277 | pr_devel("<==%s() = %d\n" , __func__, ret); |
278 | return ret; |
279 | } |
280 | EXPORT_SYMBOL_GPL(verify_pkcs7_signature); |
281 | |
282 | #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ |
283 | |
284 | #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING |
285 | void __init set_platform_trusted_keys(struct key *keyring) |
286 | { |
287 | platform_trusted_keys = keyring; |
288 | } |
289 | #endif |
290 | |