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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 | |
c2a01185 EB |
70 | * signature check fails or the key is blacklisted, -ENOPKG if the signature |
71 | * uses unsupported crypto, or some other error if there is a matching | |
72 | * certificate but the signature check cannot be performed. | |
cfb664ff | 73 | */ |
aaf66c88 | 74 | int restrict_link_by_signature(struct key *dest_keyring, |
a511e1af | 75 | const struct key_type *type, |
aaf66c88 MM |
76 | const union key_payload *payload, |
77 | struct key *trust_keyring) | |
cfb664ff | 78 | { |
a511e1af | 79 | const struct public_key_signature *sig; |
cfb664ff | 80 | struct key *key; |
a511e1af | 81 | int ret; |
cfb664ff | 82 | |
a511e1af | 83 | pr_devel("==>%s()\n", __func__); |
cfb664ff DH |
84 | |
85 | if (!trust_keyring) | |
a511e1af DH |
86 | return -ENOKEY; |
87 | ||
88 | if (type != &key_type_asymmetric) | |
cfb664ff | 89 | return -EOPNOTSUPP; |
a511e1af DH |
90 | |
91 | sig = payload->data[asym_auth]; | |
c2a01185 EB |
92 | if (!sig) |
93 | return -ENOPKG; | |
a511e1af | 94 | if (!sig->auth_ids[0] && !sig->auth_ids[1]) |
acddc720 | 95 | return -ENOKEY; |
a511e1af | 96 | |
cfb664ff DH |
97 | if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid)) |
98 | return -EPERM; | |
cfb664ff | 99 | |
a511e1af | 100 | /* See if we have a key that signed this one. */ |
cfb664ff DH |
101 | key = find_asymmetric_key(trust_keyring, |
102 | sig->auth_ids[0], sig->auth_ids[1], | |
103 | false); | |
104 | if (IS_ERR(key)) | |
a511e1af | 105 | return -ENOKEY; |
cfb664ff | 106 | |
a511e1af DH |
107 | if (use_builtin_keys && !test_bit(KEY_FLAG_BUILTIN, &key->flags)) |
108 | ret = -ENOKEY; | |
109 | else | |
110 | ret = verify_signature(key, sig); | |
cfb664ff DH |
111 | key_put(key); |
112 | return ret; | |
113 | } | |
7e3c4d22 | 114 | |
8e323a02 MM |
115 | static bool match_either_id(const struct asymmetric_key_ids *pair, |
116 | const struct asymmetric_key_id *single) | |
117 | { | |
118 | return (asymmetric_key_id_same(pair->id[0], single) || | |
119 | asymmetric_key_id_same(pair->id[1], single)); | |
120 | } | |
121 | ||
122 | static int key_or_keyring_common(struct key *dest_keyring, | |
123 | const struct key_type *type, | |
124 | const union key_payload *payload, | |
125 | struct key *trusted, bool check_dest) | |
7e3c4d22 MM |
126 | { |
127 | const struct public_key_signature *sig; | |
8e323a02 | 128 | struct key *key = NULL; |
7e3c4d22 MM |
129 | int ret; |
130 | ||
131 | pr_devel("==>%s()\n", __func__); | |
132 | ||
133 | if (!dest_keyring) | |
134 | return -ENOKEY; | |
135 | else if (dest_keyring->type != &key_type_keyring) | |
136 | return -EOPNOTSUPP; | |
137 | ||
8e323a02 | 138 | if (!trusted && !check_dest) |
7e3c4d22 MM |
139 | return -ENOKEY; |
140 | ||
141 | if (type != &key_type_asymmetric) | |
142 | return -EOPNOTSUPP; | |
143 | ||
144 | sig = payload->data[asym_auth]; | |
c2a01185 EB |
145 | if (!sig) |
146 | return -ENOPKG; | |
7e3c4d22 MM |
147 | if (!sig->auth_ids[0] && !sig->auth_ids[1]) |
148 | return -ENOKEY; | |
149 | ||
8e323a02 MM |
150 | if (trusted) { |
151 | if (trusted->type == &key_type_keyring) { | |
152 | /* See if we have a key that signed this one. */ | |
153 | key = find_asymmetric_key(trusted, sig->auth_ids[0], | |
154 | sig->auth_ids[1], false); | |
155 | if (IS_ERR(key)) | |
156 | key = NULL; | |
157 | } else if (trusted->type == &key_type_asymmetric) { | |
158 | const struct asymmetric_key_ids *signer_ids; | |
7e3c4d22 | 159 | |
8e323a02 | 160 | signer_ids = asymmetric_key_ids(trusted); |
7e3c4d22 | 161 | |
8e323a02 MM |
162 | /* |
163 | * The auth_ids come from the candidate key (the | |
164 | * one that is being considered for addition to | |
165 | * dest_keyring) and identify the key that was | |
166 | * used to sign. | |
167 | * | |
168 | * The signer_ids are identifiers for the | |
169 | * signing key specified for dest_keyring. | |
170 | * | |
171 | * The first auth_id is the preferred id, and | |
172 | * the second is the fallback. If only one | |
173 | * auth_id is present, it may match against | |
174 | * either signer_id. If two auth_ids are | |
175 | * present, the first auth_id must match one | |
176 | * signer_id and the second auth_id must match | |
177 | * the second signer_id. | |
178 | */ | |
179 | if (!sig->auth_ids[0] || !sig->auth_ids[1]) { | |
180 | const struct asymmetric_key_id *auth_id; | |
7e3c4d22 | 181 | |
8e323a02 MM |
182 | auth_id = sig->auth_ids[0] ?: sig->auth_ids[1]; |
183 | if (match_either_id(signer_ids, auth_id)) | |
184 | key = __key_get(trusted); | |
185 | ||
186 | } else if (asymmetric_key_id_same(signer_ids->id[1], | |
187 | sig->auth_ids[1]) && | |
188 | match_either_id(signer_ids, | |
189 | sig->auth_ids[0])) { | |
190 | key = __key_get(trusted); | |
191 | } | |
192 | } else { | |
193 | return -EOPNOTSUPP; | |
194 | } | |
7e3c4d22 MM |
195 | } |
196 | ||
8e323a02 MM |
197 | if (check_dest && !key) { |
198 | /* See if the destination has a key that signed this one. */ | |
199 | key = find_asymmetric_key(dest_keyring, sig->auth_ids[0], | |
200 | sig->auth_ids[1], false); | |
201 | if (IS_ERR(key)) | |
202 | key = NULL; | |
203 | } | |
204 | ||
205 | if (!key) | |
206 | return -ENOKEY; | |
207 | ||
7e3c4d22 MM |
208 | ret = key_validate(key); |
209 | if (ret == 0) | |
210 | ret = verify_signature(key, sig); | |
211 | ||
212 | key_put(key); | |
213 | return ret; | |
214 | } | |
8e323a02 MM |
215 | |
216 | /** | |
217 | * restrict_link_by_key_or_keyring - Restrict additions to a ring of public | |
218 | * keys using the restrict_key information stored in the ring. | |
219 | * @dest_keyring: Keyring being linked to. | |
220 | * @type: The type of key being added. | |
221 | * @payload: The payload of the new key. | |
222 | * @trusted: A key or ring of keys that can be used to vouch for the new cert. | |
223 | * | |
224 | * Check the new certificate only against the key or keys passed in the data | |
225 | * parameter. If one of those is the signing key and validates the new | |
226 | * certificate, then mark the new certificate as being ok to link. | |
227 | * | |
228 | * Returns 0 if the new certificate was accepted, -ENOKEY if we | |
229 | * couldn't find a matching parent certificate in the trusted list, | |
c2a01185 EB |
230 | * -EKEYREJECTED if the signature check fails, -ENOPKG if the signature uses |
231 | * unsupported crypto, or some other error if there is a matching certificate | |
232 | * but the signature check cannot be performed. | |
8e323a02 MM |
233 | */ |
234 | int restrict_link_by_key_or_keyring(struct key *dest_keyring, | |
235 | const struct key_type *type, | |
236 | const union key_payload *payload, | |
237 | struct key *trusted) | |
238 | { | |
239 | return key_or_keyring_common(dest_keyring, type, payload, trusted, | |
240 | false); | |
241 | } | |
242 | ||
243 | /** | |
244 | * restrict_link_by_key_or_keyring_chain - Restrict additions to a ring of | |
245 | * public keys using the restrict_key information stored in the ring. | |
246 | * @dest_keyring: Keyring being linked to. | |
247 | * @type: The type of key being added. | |
248 | * @payload: The payload of the new key. | |
249 | * @trusted: A key or ring of keys that can be used to vouch for the new cert. | |
250 | * | |
251 | * Check the new certificate only against the key or keys passed in the data | |
252 | * parameter. If one of those is the signing key and validates the new | |
253 | * certificate, then mark the new certificate as being ok to link. | |
254 | * | |
255 | * Returns 0 if the new certificate was accepted, -ENOKEY if we | |
256 | * couldn't find a matching parent certificate in the trusted list, | |
c2a01185 EB |
257 | * -EKEYREJECTED if the signature check fails, -ENOPKG if the signature uses |
258 | * unsupported crypto, or some other error if there is a matching certificate | |
259 | * but the signature check cannot be performed. | |
8e323a02 MM |
260 | */ |
261 | int restrict_link_by_key_or_keyring_chain(struct key *dest_keyring, | |
262 | const struct key_type *type, | |
263 | const union key_payload *payload, | |
264 | struct key *trusted) | |
265 | { | |
266 | return key_or_keyring_common(dest_keyring, type, payload, trusted, | |
267 | true); | |
268 | } |