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b56e5a17 DH |
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> | |
091f6e26 | 19 | #include <crypto/pkcs7.h> |
b56e5a17 | 20 | |
a511e1af | 21 | static struct key *system_trusted_keyring; |
b56e5a17 DH |
22 | |
23 | extern __initconst const u8 system_certificate_list[]; | |
62226983 | 24 | extern __initconst const unsigned long system_certificate_list_size; |
b56e5a17 | 25 | |
a511e1af DH |
26 | /** |
27 | * restrict_link_by_builtin_trusted - Restrict keyring addition by system CA | |
28 | * | |
29 | * Restrict the addition of keys into a keyring based on the key-to-be-added | |
30 | * being vouched for by a key in the system keyring. | |
31 | */ | |
32 | int restrict_link_by_builtin_trusted(struct key *keyring, | |
33 | const struct key_type *type, | |
a511e1af DH |
34 | const union key_payload *payload) |
35 | { | |
36 | return restrict_link_by_signature(system_trusted_keyring, | |
37 | type, payload); | |
38 | } | |
39 | ||
b56e5a17 DH |
40 | /* |
41 | * Load the compiled-in keys | |
42 | */ | |
43 | static __init int system_trusted_keyring_init(void) | |
44 | { | |
45 | pr_notice("Initialise system trusted keyring\n"); | |
46 | ||
47 | system_trusted_keyring = | |
48 | keyring_alloc(".system_keyring", | |
49 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), | |
50 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | | |
af34cb0c | 51 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), |
5ac7eace | 52 | KEY_ALLOC_NOT_IN_QUOTA, |
a511e1af | 53 | restrict_link_by_builtin_trusted, NULL); |
b56e5a17 DH |
54 | if (IS_ERR(system_trusted_keyring)) |
55 | panic("Can't allocate system trusted keyring\n"); | |
b56e5a17 DH |
56 | return 0; |
57 | } | |
58 | ||
59 | /* | |
60 | * Must be initialised before we try and load the keys into the keyring. | |
61 | */ | |
62 | device_initcall(system_trusted_keyring_init); | |
63 | ||
64 | /* | |
65 | * Load the compiled-in list of X.509 certificates. | |
66 | */ | |
67 | static __init int load_system_certificate_list(void) | |
68 | { | |
69 | key_ref_t key; | |
70 | const u8 *p, *end; | |
71 | size_t plen; | |
72 | ||
73 | pr_notice("Loading compiled-in X.509 certificates\n"); | |
74 | ||
b56e5a17 | 75 | p = system_certificate_list; |
62226983 | 76 | end = p + system_certificate_list_size; |
b56e5a17 DH |
77 | while (p < end) { |
78 | /* Each cert begins with an ASN.1 SEQUENCE tag and must be more | |
79 | * than 256 bytes in size. | |
80 | */ | |
81 | if (end - p < 4) | |
82 | goto dodgy_cert; | |
83 | if (p[0] != 0x30 && | |
84 | p[1] != 0x82) | |
85 | goto dodgy_cert; | |
86 | plen = (p[2] << 8) | p[3]; | |
87 | plen += 4; | |
88 | if (plen > end - p) | |
89 | goto dodgy_cert; | |
90 | ||
91 | key = key_create_or_update(make_key_ref(system_trusted_keyring, 1), | |
92 | "asymmetric", | |
93 | NULL, | |
94 | p, | |
95 | plen, | |
af34cb0c MZ |
96 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
97 | KEY_USR_VIEW | KEY_USR_READ), | |
008643b8 | 98 | KEY_ALLOC_NOT_IN_QUOTA | |
5ac7eace DH |
99 | KEY_ALLOC_BUILT_IN | |
100 | KEY_ALLOC_BYPASS_RESTRICTION); | |
b56e5a17 DH |
101 | if (IS_ERR(key)) { |
102 | pr_err("Problem loading in-kernel X.509 certificate (%ld)\n", | |
103 | PTR_ERR(key)); | |
104 | } else { | |
105 | pr_notice("Loaded X.509 cert '%s'\n", | |
106 | key_ref_to_ptr(key)->description); | |
107 | key_ref_put(key); | |
108 | } | |
109 | p += plen; | |
110 | } | |
111 | ||
112 | return 0; | |
113 | ||
114 | dodgy_cert: | |
115 | pr_err("Problem parsing in-kernel X.509 certificate list\n"); | |
116 | return 0; | |
117 | } | |
118 | late_initcall(load_system_certificate_list); | |
091f6e26 DH |
119 | |
120 | #ifdef CONFIG_SYSTEM_DATA_VERIFICATION | |
121 | ||
122 | /** | |
e68503bd DH |
123 | * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. |
124 | * @data: The data to be verified (NULL if expecting internal data). | |
091f6e26 DH |
125 | * @len: Size of @data. |
126 | * @raw_pkcs7: The PKCS#7 message that is the signature. | |
127 | * @pkcs7_len: The size of @raw_pkcs7. | |
e68503bd | 128 | * @trusted_keys: Trusted keys to use (NULL for system_trusted_keyring). |
99db4435 | 129 | * @usage: The use to which the key is being put. |
e68503bd DH |
130 | * @view_content: Callback to gain access to content. |
131 | * @ctx: Context for callback. | |
091f6e26 | 132 | */ |
e68503bd DH |
133 | int verify_pkcs7_signature(const void *data, size_t len, |
134 | const void *raw_pkcs7, size_t pkcs7_len, | |
135 | struct key *trusted_keys, | |
e68503bd DH |
136 | enum key_being_used_for usage, |
137 | int (*view_content)(void *ctx, | |
138 | const void *data, size_t len, | |
139 | size_t asn1hdrlen), | |
140 | void *ctx) | |
091f6e26 DH |
141 | { |
142 | struct pkcs7_message *pkcs7; | |
091f6e26 DH |
143 | int ret; |
144 | ||
145 | pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); | |
146 | if (IS_ERR(pkcs7)) | |
147 | return PTR_ERR(pkcs7); | |
148 | ||
149 | /* The data should be detached - so we need to supply it. */ | |
e68503bd | 150 | if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { |
091f6e26 DH |
151 | pr_err("PKCS#7 signature with non-detached data\n"); |
152 | ret = -EBADMSG; | |
153 | goto error; | |
154 | } | |
155 | ||
99db4435 | 156 | ret = pkcs7_verify(pkcs7, usage); |
091f6e26 DH |
157 | if (ret < 0) |
158 | goto error; | |
159 | ||
e68503bd DH |
160 | if (!trusted_keys) |
161 | trusted_keys = system_trusted_keyring; | |
bda850cd DH |
162 | ret = pkcs7_validate_trust(pkcs7, trusted_keys); |
163 | if (ret < 0) { | |
164 | if (ret == -ENOKEY) | |
165 | pr_err("PKCS#7 signature not signed with a trusted key\n"); | |
e68503bd DH |
166 | goto error; |
167 | } | |
168 | ||
169 | if (view_content) { | |
170 | size_t asn1hdrlen; | |
171 | ||
172 | ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); | |
173 | if (ret < 0) { | |
174 | if (ret == -ENODATA) | |
175 | pr_devel("PKCS#7 message does not contain data\n"); | |
176 | goto error; | |
177 | } | |
178 | ||
179 | ret = view_content(ctx, data, len, asn1hdrlen); | |
091f6e26 DH |
180 | } |
181 | ||
182 | error: | |
183 | pkcs7_free_message(pkcs7); | |
184 | pr_devel("<==%s() = %d\n", __func__, ret); | |
185 | return ret; | |
186 | } | |
e68503bd | 187 | EXPORT_SYMBOL_GPL(verify_pkcs7_signature); |
091f6e26 DH |
188 | |
189 | #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ |