md-multipath: Use seq_putc() in multipath_status()
[sfrench/cifs-2.6.git] / certs / system_keyring.c
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
22 static struct key *builtin_trusted_keys;
23 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
24 static struct key *secondary_trusted_keys;
25 #endif
26
27 extern __initconst const u8 system_certificate_list[];
28 extern __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  */
36 int 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  */
54 int 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  */
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 }
90 #endif
91
92 /*
93  * Create the trusted keyrings
94  */
95 static __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  */
132 device_initcall(system_trusted_keyring_init);
133
134 /*
135  * Load the compiled-in list of X.509 certificates.
136  */
137 static __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
184 dodgy_cert:
185         pr_err("Problem parsing in-kernel X.509 certificate list\n");
186         return 0;
187 }
188 late_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  */
204 int 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
260 error:
261         pkcs7_free_message(pkcs7);
262         pr_devel("<==%s() = %d\n", __func__, ret);
263         return ret;
264 }
265 EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
266
267 #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */