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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 <keys/asymmetric-type.h>
18#include <keys/system_keyring.h>
19#include <crypto/pkcs7.h>
20
21struct key *system_trusted_keyring;
22EXPORT_SYMBOL_GPL(system_trusted_keyring);
23
24extern __initconst const u8 system_certificate_list[];
25extern __initconst const unsigned long system_certificate_list_size;
26
27/*
28 * Load the compiled-in keys
29 */
30static __init int system_trusted_keyring_init(void)
31{
32 pr_notice("Initialise system trusted keyring\n");
33
34 system_trusted_keyring =
35 keyring_alloc(".system_keyring",
36 KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
37 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
38 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
39 KEY_ALLOC_NOT_IN_QUOTA, NULL);
40 if (IS_ERR(system_trusted_keyring))
41 panic("Can't allocate system trusted keyring\n");
42
43 set_bit(KEY_FLAG_TRUSTED_ONLY, &system_trusted_keyring->flags);
44 return 0;
45}
46
47/*
48 * Must be initialised before we try and load the keys into the keyring.
49 */
50device_initcall(system_trusted_keyring_init);
51
52/*
53 * Load the compiled-in list of X.509 certificates.
54 */
55static __init int load_system_certificate_list(void)
56{
57 key_ref_t key;
58 const u8 *p, *end;
59 size_t plen;
60
61 pr_notice("Loading compiled-in X.509 certificates\n");
62
63 p = system_certificate_list;
64 end = p + system_certificate_list_size;
65 while (p < end) {
66 /* Each cert begins with an ASN.1 SEQUENCE tag and must be more
67 * than 256 bytes in size.
68 */
69 if (end - p < 4)
70 goto dodgy_cert;
71 if (p[0] != 0x30 &&
72 p[1] != 0x82)
73 goto dodgy_cert;
74 plen = (p[2] << 8) | p[3];
75 plen += 4;
76 if (plen > end - p)
77 goto dodgy_cert;
78
79 key = key_create_or_update(make_key_ref(system_trusted_keyring, 1),
80 "asymmetric",
81 NULL,
82 p,
83 plen,
84 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
85 KEY_USR_VIEW | KEY_USR_READ),
86 KEY_ALLOC_NOT_IN_QUOTA |
87 KEY_ALLOC_TRUSTED |
88 KEY_ALLOC_BUILT_IN);
89 if (IS_ERR(key)) {
90 pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
91 PTR_ERR(key));
92 } else {
93 pr_notice("Loaded X.509 cert '%s'\n",
94 key_ref_to_ptr(key)->description);
95 key_ref_put(key);
96 }
97 p += plen;
98 }
99
100 return 0;
101
102dodgy_cert:
103 pr_err("Problem parsing in-kernel X.509 certificate list\n");
104 return 0;
105}
106late_initcall(load_system_certificate_list);
107
108#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
109
110/**
111 * Verify a PKCS#7-based signature on system data.
112 * @data: The data to be verified.
113 * @len: Size of @data.
114 * @raw_pkcs7: The PKCS#7 message that is the signature.
115 * @pkcs7_len: The size of @raw_pkcs7.
116 * @usage: The use to which the key is being put.
117 */
118int system_verify_data(const void *data, unsigned long len,
119 const void *raw_pkcs7, size_t pkcs7_len,
120 enum key_being_used_for usage)
121{
122 struct pkcs7_message *pkcs7;
123 bool trusted;
124 int ret;
125
126 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
127 if (IS_ERR(pkcs7))
128 return PTR_ERR(pkcs7);
129
130 /* The data should be detached - so we need to supply it. */
131 if (pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
132 pr_err("PKCS#7 signature with non-detached data\n");
133 ret = -EBADMSG;
134 goto error;
135 }
136
137 ret = pkcs7_verify(pkcs7, usage);
138 if (ret < 0)
139 goto error;
140
141 ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);
142 if (ret < 0)
143 goto error;
144
145 if (!trusted) {
146 pr_err("PKCS#7 signature not signed with a trusted key\n");
147 ret = -ENOKEY;
148 }
149
150error:
151 pkcs7_free_message(pkcs7);
152 pr_devel("<==%s() = %d\n", __func__, ret);
153 return ret;
154}
155EXPORT_SYMBOL_GPL(system_verify_data);
156
157#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
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 */