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David Howellsb56e5a12013-08-30 16:07:30 +01001/* 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>
Yannik Sembritzki40b08cd2018-08-16 14:05:10 +010017#include <linux/verification.h>
David Howellsb56e5a12013-08-30 16:07:30 +010018#include <keys/asymmetric-type.h>
19#include <keys/system_keyring.h>
David Howells091f6e22015-07-20 21:16:28 +010020#include <crypto/pkcs7.h>
David Howellsb56e5a12013-08-30 16:07:30 +010021
David Howellsd3bfe842016-04-06 16:14:27 +010022static struct key *builtin_trusted_keys;
23#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
24static struct key *secondary_trusted_keys;
25#endif
David Howellsb56e5a12013-08-30 16:07:30 +010026
27extern __initconst const u8 system_certificate_list[];
Hendrik Brueckner62226982013-12-05 14:48:22 +010028extern __initconst const unsigned long system_certificate_list_size;
David Howellsb56e5a12013-08-30 16:07:30 +010029
David Howellsa511e1a2016-04-06 16:14:26 +010030/**
David Howellsd3bfe842016-04-06 16:14:27 +010031 * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA
David Howellsa511e1a2016-04-06 16:14:26 +010032 *
33 * Restrict the addition of keys into a keyring based on the key-to-be-added
David Howellsd3bfe842016-04-06 16:14:27 +010034 * being vouched for by a key in the built in system keyring.
David Howellsa511e1a2016-04-06 16:14:26 +010035 */
36int restrict_link_by_builtin_trusted(struct key *keyring,
37 const struct key_type *type,
David Howellsa511e1a2016-04-06 16:14:26 +010038 const union key_payload *payload)
39{
David Howellsd3bfe842016-04-06 16:14:27 +010040 return restrict_link_by_signature(builtin_trusted_keys, type, payload);
David Howellsa511e1a2016-04-06 16:14:26 +010041}
42
David Howellsd3bfe842016-04-06 16:14:27 +010043#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
44/**
45 * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring
46 * addition by both builtin and secondary keyrings
47 *
48 * Restrict the addition of keys into a keyring based on the key-to-be-added
49 * being vouched for by a key in either the built-in or the secondary system
50 * keyrings.
51 */
52int restrict_link_by_builtin_and_secondary_trusted(
53 struct key *keyring,
54 const struct key_type *type,
55 const union key_payload *payload)
56{
57 /* If we have a secondary trusted keyring, then that contains a link
58 * through to the builtin keyring and the search will follow that link.
59 */
60 if (type == &key_type_keyring &&
61 keyring == secondary_trusted_keys &&
62 payload == &builtin_trusted_keys->payload)
63 /* Allow the builtin keyring to be added to the secondary */
64 return 0;
65
66 return restrict_link_by_signature(secondary_trusted_keys, type, payload);
67}
68#endif
69
David Howellsb56e5a12013-08-30 16:07:30 +010070/*
David Howellsd3bfe842016-04-06 16:14:27 +010071 * Create the trusted keyrings
David Howellsb56e5a12013-08-30 16:07:30 +010072 */
73static __init int system_trusted_keyring_init(void)
74{
David Howellsd3bfe842016-04-06 16:14:27 +010075 pr_notice("Initialise system trusted keyrings\n");
David Howellsb56e5a12013-08-30 16:07:30 +010076
David Howellsd3bfe842016-04-06 16:14:27 +010077 builtin_trusted_keys =
78 keyring_alloc(".builtin_trusted_keys",
David Howellsb56e5a12013-08-30 16:07:30 +010079 KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
80 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
Mimi Zoharaf34cb02013-08-20 14:36:26 -040081 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
David Howells5ac7eac2016-04-06 16:14:24 +010082 KEY_ALLOC_NOT_IN_QUOTA,
David Howellsd3bfe842016-04-06 16:14:27 +010083 NULL, NULL);
84 if (IS_ERR(builtin_trusted_keys))
85 panic("Can't allocate builtin trusted keyring\n");
86
87#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
88 secondary_trusted_keys =
89 keyring_alloc(".secondary_trusted_keys",
90 KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
91 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
92 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH |
93 KEY_USR_WRITE),
94 KEY_ALLOC_NOT_IN_QUOTA,
95 restrict_link_by_builtin_and_secondary_trusted,
96 NULL);
97 if (IS_ERR(secondary_trusted_keys))
98 panic("Can't allocate secondary trusted keyring\n");
99
100 if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0)
101 panic("Can't link trusted keyrings\n");
102#endif
103
David Howellsb56e5a12013-08-30 16:07:30 +0100104 return 0;
105}
106
107/*
108 * Must be initialised before we try and load the keys into the keyring.
109 */
110device_initcall(system_trusted_keyring_init);
111
112/*
113 * Load the compiled-in list of X.509 certificates.
114 */
115static __init int load_system_certificate_list(void)
116{
117 key_ref_t key;
118 const u8 *p, *end;
119 size_t plen;
120
121 pr_notice("Loading compiled-in X.509 certificates\n");
122
David Howellsb56e5a12013-08-30 16:07:30 +0100123 p = system_certificate_list;
Hendrik Brueckner62226982013-12-05 14:48:22 +0100124 end = p + system_certificate_list_size;
David Howellsb56e5a12013-08-30 16:07:30 +0100125 while (p < end) {
126 /* Each cert begins with an ASN.1 SEQUENCE tag and must be more
127 * than 256 bytes in size.
128 */
129 if (end - p < 4)
130 goto dodgy_cert;
131 if (p[0] != 0x30 &&
132 p[1] != 0x82)
133 goto dodgy_cert;
134 plen = (p[2] << 8) | p[3];
135 plen += 4;
136 if (plen > end - p)
137 goto dodgy_cert;
138
David Howellsd3bfe842016-04-06 16:14:27 +0100139 key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1),
David Howellsb56e5a12013-08-30 16:07:30 +0100140 "asymmetric",
141 NULL,
142 p,
143 plen,
Mimi Zoharaf34cb02013-08-20 14:36:26 -0400144 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
145 KEY_USR_VIEW | KEY_USR_READ),
David Howells008643b2013-08-30 16:07:37 +0100146 KEY_ALLOC_NOT_IN_QUOTA |
David Howells5ac7eac2016-04-06 16:14:24 +0100147 KEY_ALLOC_BUILT_IN |
148 KEY_ALLOC_BYPASS_RESTRICTION);
David Howellsb56e5a12013-08-30 16:07:30 +0100149 if (IS_ERR(key)) {
150 pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
151 PTR_ERR(key));
152 } else {
David Howellsb56e5a12013-08-30 16:07:30 +0100153 pr_notice("Loaded X.509 cert '%s'\n",
154 key_ref_to_ptr(key)->description);
155 key_ref_put(key);
156 }
157 p += plen;
158 }
159
160 return 0;
161
162dodgy_cert:
163 pr_err("Problem parsing in-kernel X.509 certificate list\n");
164 return 0;
165}
166late_initcall(load_system_certificate_list);
David Howells091f6e22015-07-20 21:16:28 +0100167
168#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
169
170/**
David Howellse68503b2016-04-06 16:14:24 +0100171 * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
172 * @data: The data to be verified (NULL if expecting internal data).
David Howells091f6e22015-07-20 21:16:28 +0100173 * @len: Size of @data.
174 * @raw_pkcs7: The PKCS#7 message that is the signature.
175 * @pkcs7_len: The size of @raw_pkcs7.
David Howellsd3bfe842016-04-06 16:14:27 +0100176 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
177 * (void *)1UL for all trusted keys).
David Howells99db4432015-08-05 15:22:27 +0100178 * @usage: The use to which the key is being put.
David Howellse68503b2016-04-06 16:14:24 +0100179 * @view_content: Callback to gain access to content.
180 * @ctx: Context for callback.
David Howells091f6e22015-07-20 21:16:28 +0100181 */
David Howellse68503b2016-04-06 16:14:24 +0100182int verify_pkcs7_signature(const void *data, size_t len,
183 const void *raw_pkcs7, size_t pkcs7_len,
184 struct key *trusted_keys,
David Howellse68503b2016-04-06 16:14:24 +0100185 enum key_being_used_for usage,
186 int (*view_content)(void *ctx,
187 const void *data, size_t len,
188 size_t asn1hdrlen),
189 void *ctx)
David Howells091f6e22015-07-20 21:16:28 +0100190{
191 struct pkcs7_message *pkcs7;
David Howells091f6e22015-07-20 21:16:28 +0100192 int ret;
193
194 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
195 if (IS_ERR(pkcs7))
196 return PTR_ERR(pkcs7);
197
198 /* The data should be detached - so we need to supply it. */
David Howellse68503b2016-04-06 16:14:24 +0100199 if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
David Howells091f6e22015-07-20 21:16:28 +0100200 pr_err("PKCS#7 signature with non-detached data\n");
201 ret = -EBADMSG;
202 goto error;
203 }
204
David Howells99db4432015-08-05 15:22:27 +0100205 ret = pkcs7_verify(pkcs7, usage);
David Howells091f6e22015-07-20 21:16:28 +0100206 if (ret < 0)
207 goto error;
208
David Howellsd3bfe842016-04-06 16:14:27 +0100209 if (!trusted_keys) {
210 trusted_keys = builtin_trusted_keys;
Yannik Sembritzki40b08cd2018-08-16 14:05:10 +0100211 } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) {
David Howellsd3bfe842016-04-06 16:14:27 +0100212#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
213 trusted_keys = secondary_trusted_keys;
214#else
215 trusted_keys = builtin_trusted_keys;
216#endif
217 }
David Howellsbda850c2016-04-06 16:14:24 +0100218 ret = pkcs7_validate_trust(pkcs7, trusted_keys);
219 if (ret < 0) {
220 if (ret == -ENOKEY)
221 pr_err("PKCS#7 signature not signed with a trusted key\n");
David Howellse68503b2016-04-06 16:14:24 +0100222 goto error;
223 }
224
225 if (view_content) {
226 size_t asn1hdrlen;
227
228 ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);
229 if (ret < 0) {
230 if (ret == -ENODATA)
231 pr_devel("PKCS#7 message does not contain data\n");
232 goto error;
233 }
234
235 ret = view_content(ctx, data, len, asn1hdrlen);
David Howells091f6e22015-07-20 21:16:28 +0100236 }
237
238error:
239 pkcs7_free_message(pkcs7);
240 pr_devel("<==%s() = %d\n", __func__, ret);
241 return ret;
242}
David Howellse68503b2016-04-06 16:14:24 +0100243EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
David Howells091f6e22015-07-20 21:16:28 +0100244
245#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */