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cfb664ff DH |
1 | /* Instantiate a public key crypto key from an X.509 Certificate |
2 | * | |
a511e1af | 3 | * Copyright (C) 2012, 2016 Red Hat, Inc. All Rights Reserved. |
cfb664ff DH |
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 | ||
a511e1af | 12 | #define pr_fmt(fmt) "ASYM: "fmt |
cfb664ff DH |
13 | #include <linux/module.h> |
14 | #include <linux/kernel.h> | |
cfb664ff | 15 | #include <linux/err.h> |
cfb664ff DH |
16 | #include <crypto/public_key.h> |
17 | #include "asymmetric_keys.h" | |
cfb664ff DH |
18 | |
19 | static bool use_builtin_keys; | |
20 | static struct asymmetric_key_id *ca_keyid; | |
21 | ||
22 | #ifndef MODULE | |
23 | static struct { | |
24 | struct asymmetric_key_id id; | |
25 | unsigned char data[10]; | |
26 | } cakey; | |
27 | ||
28 | static int __init ca_keys_setup(char *str) | |
29 | { | |
30 | if (!str) /* default system keyring */ | |
31 | return 1; | |
32 | ||
33 | if (strncmp(str, "id:", 3) == 0) { | |
34 | struct asymmetric_key_id *p = &cakey.id; | |
35 | size_t hexlen = (strlen(str) - 3) / 2; | |
36 | int ret; | |
37 | ||
38 | if (hexlen == 0 || hexlen > sizeof(cakey.data)) { | |
39 | pr_err("Missing or invalid ca_keys id\n"); | |
40 | return 1; | |
41 | } | |
42 | ||
43 | ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen); | |
44 | if (ret < 0) | |
45 | pr_err("Unparsable ca_keys id hex string\n"); | |
46 | else | |
47 | ca_keyid = p; /* owner key 'id:xxxxxx' */ | |
48 | } else if (strcmp(str, "builtin") == 0) { | |
49 | use_builtin_keys = true; | |
50 | } | |
51 | ||
52 | return 1; | |
53 | } | |
54 | __setup("ca_keys=", ca_keys_setup); | |
55 | #endif | |
56 | ||
a511e1af DH |
57 | /** |
58 | * restrict_link_by_signature - Restrict additions to a ring of public keys | |
aaf66c88 | 59 | * @dest_keyring: Keyring being linked to. |
a511e1af DH |
60 | * @type: The type of key being added. |
61 | * @payload: The payload of the new key. | |
aaf66c88 | 62 | * @trust_keyring: A ring of keys that can be used to vouch for the new cert. |
a511e1af | 63 | * |
cfb664ff DH |
64 | * Check the new certificate against the ones in the trust keyring. If one of |
65 | * those is the signing key and validates the new certificate, then mark the | |
66 | * new certificate as being trusted. | |
67 | * | |
a511e1af DH |
68 | * Returns 0 if the new certificate was accepted, -ENOKEY if we couldn't find a |
69 | * matching parent certificate in the trusted list, -EKEYREJECTED if the | |
70 | * signature check fails or the key is blacklisted and some other error if | |
71 | * there is a matching certificate but the signature check cannot be performed. | |
cfb664ff | 72 | */ |
aaf66c88 | 73 | int restrict_link_by_signature(struct key *dest_keyring, |
a511e1af | 74 | const struct key_type *type, |
aaf66c88 MM |
75 | const union key_payload *payload, |
76 | struct key *trust_keyring) | |
cfb664ff | 77 | { |
a511e1af | 78 | const struct public_key_signature *sig; |
cfb664ff | 79 | struct key *key; |
a511e1af | 80 | int ret; |
cfb664ff | 81 | |
a511e1af | 82 | pr_devel("==>%s()\n", __func__); |
cfb664ff DH |
83 | |
84 | if (!trust_keyring) | |
a511e1af DH |
85 | return -ENOKEY; |
86 | ||
87 | if (type != &key_type_asymmetric) | |
cfb664ff | 88 | return -EOPNOTSUPP; |
a511e1af DH |
89 | |
90 | sig = payload->data[asym_auth]; | |
91 | if (!sig->auth_ids[0] && !sig->auth_ids[1]) | |
acddc720 | 92 | return -ENOKEY; |
a511e1af | 93 | |
cfb664ff DH |
94 | if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid)) |
95 | return -EPERM; | |
cfb664ff | 96 | |
a511e1af | 97 | /* See if we have a key that signed this one. */ |
cfb664ff DH |
98 | key = find_asymmetric_key(trust_keyring, |
99 | sig->auth_ids[0], sig->auth_ids[1], | |
100 | false); | |
101 | if (IS_ERR(key)) | |
a511e1af | 102 | return -ENOKEY; |
cfb664ff | 103 | |
a511e1af DH |
104 | if (use_builtin_keys && !test_bit(KEY_FLAG_BUILTIN, &key->flags)) |
105 | ret = -ENOKEY; | |
106 | else | |
107 | ret = verify_signature(key, sig); | |
cfb664ff DH |
108 | key_put(key); |
109 | return ret; | |
110 | } | |
7e3c4d22 | 111 | |
8e323a02 MM |
112 | static bool match_either_id(const struct asymmetric_key_ids *pair, |
113 | const struct asymmetric_key_id *single) | |
114 | { | |
115 | return (asymmetric_key_id_same(pair->id[0], single) || | |
116 | asymmetric_key_id_same(pair->id[1], single)); | |
117 | } | |
118 | ||
119 | static int key_or_keyring_common(struct key *dest_keyring, | |
120 | const struct key_type *type, | |
121 | const union key_payload *payload, | |
122 | struct key *trusted, bool check_dest) | |
7e3c4d22 MM |
123 | { |
124 | const struct public_key_signature *sig; | |
8e323a02 | 125 | struct key *key = NULL; |
7e3c4d22 MM |
126 | int ret; |
127 | ||
128 | pr_devel("==>%s()\n", __func__); | |
129 | ||
130 | if (!dest_keyring) | |
131 | return -ENOKEY; | |
132 | else if (dest_keyring->type != &key_type_keyring) | |
133 | return -EOPNOTSUPP; | |
134 | ||
8e323a02 | 135 | if (!trusted && !check_dest) |
7e3c4d22 MM |
136 | return -ENOKEY; |
137 | ||
138 | if (type != &key_type_asymmetric) | |
139 | return -EOPNOTSUPP; | |
140 | ||
141 | sig = payload->data[asym_auth]; | |
142 | if (!sig->auth_ids[0] && !sig->auth_ids[1]) | |
143 | return -ENOKEY; | |
144 | ||
8e323a02 MM |
145 | if (trusted) { |
146 | if (trusted->type == &key_type_keyring) { | |
147 | /* See if we have a key that signed this one. */ | |
148 | key = find_asymmetric_key(trusted, sig->auth_ids[0], | |
149 | sig->auth_ids[1], false); | |
150 | if (IS_ERR(key)) | |
151 | key = NULL; | |
152 | } else if (trusted->type == &key_type_asymmetric) { | |
153 | const struct asymmetric_key_ids *signer_ids; | |
7e3c4d22 | 154 | |
8e323a02 | 155 | signer_ids = asymmetric_key_ids(trusted); |
7e3c4d22 | 156 | |
8e323a02 MM |
157 | /* |
158 | * The auth_ids come from the candidate key (the | |
159 | * one that is being considered for addition to | |
160 | * dest_keyring) and identify the key that was | |
161 | * used to sign. | |
162 | * | |
163 | * The signer_ids are identifiers for the | |
164 | * signing key specified for dest_keyring. | |
165 | * | |
166 | * The first auth_id is the preferred id, and | |
167 | * the second is the fallback. If only one | |
168 | * auth_id is present, it may match against | |
169 | * either signer_id. If two auth_ids are | |
170 | * present, the first auth_id must match one | |
171 | * signer_id and the second auth_id must match | |
172 | * the second signer_id. | |
173 | */ | |
174 | if (!sig->auth_ids[0] || !sig->auth_ids[1]) { | |
175 | const struct asymmetric_key_id *auth_id; | |
7e3c4d22 | 176 | |
8e323a02 MM |
177 | auth_id = sig->auth_ids[0] ?: sig->auth_ids[1]; |
178 | if (match_either_id(signer_ids, auth_id)) | |
179 | key = __key_get(trusted); | |
180 | ||
181 | } else if (asymmetric_key_id_same(signer_ids->id[1], | |
182 | sig->auth_ids[1]) && | |
183 | match_either_id(signer_ids, | |
184 | sig->auth_ids[0])) { | |
185 | key = __key_get(trusted); | |
186 | } | |
187 | } else { | |
188 | return -EOPNOTSUPP; | |
189 | } | |
7e3c4d22 MM |
190 | } |
191 | ||
8e323a02 MM |
192 | if (check_dest && !key) { |
193 | /* See if the destination has a key that signed this one. */ | |
194 | key = find_asymmetric_key(dest_keyring, sig->auth_ids[0], | |
195 | sig->auth_ids[1], false); | |
196 | if (IS_ERR(key)) | |
197 | key = NULL; | |
198 | } | |
199 | ||
200 | if (!key) | |
201 | return -ENOKEY; | |
202 | ||
7e3c4d22 MM |
203 | ret = key_validate(key); |
204 | if (ret == 0) | |
205 | ret = verify_signature(key, sig); | |
206 | ||
207 | key_put(key); | |
208 | return ret; | |
209 | } | |
8e323a02 MM |
210 | |
211 | /** | |
212 | * restrict_link_by_key_or_keyring - Restrict additions to a ring of public | |
213 | * keys using the restrict_key information stored in the ring. | |
214 | * @dest_keyring: Keyring being linked to. | |
215 | * @type: The type of key being added. | |
216 | * @payload: The payload of the new key. | |
217 | * @trusted: A key or ring of keys that can be used to vouch for the new cert. | |
218 | * | |
219 | * Check the new certificate only against the key or keys passed in the data | |
220 | * parameter. If one of those is the signing key and validates the new | |
221 | * certificate, then mark the new certificate as being ok to link. | |
222 | * | |
223 | * Returns 0 if the new certificate was accepted, -ENOKEY if we | |
224 | * couldn't find a matching parent certificate in the trusted list, | |
225 | * -EKEYREJECTED if the signature check fails, and some other error if | |
226 | * there is a matching certificate but the signature check cannot be | |
227 | * performed. | |
228 | */ | |
229 | int restrict_link_by_key_or_keyring(struct key *dest_keyring, | |
230 | const struct key_type *type, | |
231 | const union key_payload *payload, | |
232 | struct key *trusted) | |
233 | { | |
234 | return key_or_keyring_common(dest_keyring, type, payload, trusted, | |
235 | false); | |
236 | } | |
237 | ||
238 | /** | |
239 | * restrict_link_by_key_or_keyring_chain - Restrict additions to a ring of | |
240 | * public keys using the restrict_key information stored in the ring. | |
241 | * @dest_keyring: Keyring being linked to. | |
242 | * @type: The type of key being added. | |
243 | * @payload: The payload of the new key. | |
244 | * @trusted: A key or ring of keys that can be used to vouch for the new cert. | |
245 | * | |
246 | * Check the new certificate only against the key or keys passed in the data | |
247 | * parameter. If one of those is the signing key and validates the new | |
248 | * certificate, then mark the new certificate as being ok to link. | |
249 | * | |
250 | * Returns 0 if the new certificate was accepted, -ENOKEY if we | |
251 | * couldn't find a matching parent certificate in the trusted list, | |
252 | * -EKEYREJECTED if the signature check fails, and some other error if | |
253 | * there is a matching certificate but the signature check cannot be | |
254 | * performed. | |
255 | */ | |
256 | int restrict_link_by_key_or_keyring_chain(struct key *dest_keyring, | |
257 | const struct key_type *type, | |
258 | const union key_payload *payload, | |
259 | struct key *trusted) | |
260 | { | |
261 | return key_or_keyring_common(dest_keyring, type, payload, trusted, | |
262 | true); | |
263 | } |