1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Instantiate a public key crypto key from an X.509 Certificate
4 * Copyright (C) 2012, 2016 Red Hat, Inc. All Rights Reserved.
8 #define pr_fmt(fmt) "ASYM: "fmt
9 #include <linux/module.h>
10 #include <linux/kernel.h>
11 #include <linux/err.h>
12 #include <crypto/public_key.h>
13 #include "asymmetric_keys.h"
15 static bool use_builtin_keys;
16 static struct asymmetric_key_id *ca_keyid;
20 struct asymmetric_key_id id;
21 unsigned char data[10];
24 static int __init ca_keys_setup(char *str)
26 if (!str) /* default system keyring */
29 if (strncmp(str, "id:", 3) == 0) {
30 struct asymmetric_key_id *p = &cakey.id;
31 size_t hexlen = (strlen(str) - 3) / 2;
34 if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
35 pr_err("Missing or invalid ca_keys id\n");
39 ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
41 pr_err("Unparsable ca_keys id hex string\n");
43 ca_keyid = p; /* owner key 'id:xxxxxx' */
44 } else if (strcmp(str, "builtin") == 0) {
45 use_builtin_keys = true;
50 __setup("ca_keys=", ca_keys_setup);
54 * restrict_link_by_signature - Restrict additions to a ring of public keys
55 * @dest_keyring: Keyring being linked to.
56 * @type: The type of key being added.
57 * @payload: The payload of the new key.
58 * @trust_keyring: A ring of keys that can be used to vouch for the new cert.
60 * Check the new certificate against the ones in the trust keyring. If one of
61 * those is the signing key and validates the new certificate, then mark the
62 * new certificate as being trusted.
64 * Returns 0 if the new certificate was accepted, -ENOKEY if we couldn't find a
65 * matching parent certificate in the trusted list, -EKEYREJECTED if the
66 * signature check fails or the key is blacklisted, -ENOPKG if the signature
67 * uses unsupported crypto, or some other error if there is a matching
68 * certificate but the signature check cannot be performed.
70 int restrict_link_by_signature(struct key *dest_keyring,
71 const struct key_type *type,
72 const union key_payload *payload,
73 struct key *trust_keyring)
75 const struct public_key_signature *sig;
79 pr_devel("==>%s()\n", __func__);
84 if (type != &key_type_asymmetric)
87 sig = payload->data[asym_auth];
90 if (!sig->auth_ids[0] && !sig->auth_ids[1] && !sig->auth_ids[2])
93 if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid))
96 /* See if we have a key that signed this one. */
97 key = find_asymmetric_key(trust_keyring,
98 sig->auth_ids[0], sig->auth_ids[1],
99 sig->auth_ids[2], false);
103 if (use_builtin_keys && !test_bit(KEY_FLAG_BUILTIN, &key->flags))
106 ret = verify_signature(key, sig);
112 * restrict_link_by_ca - Restrict additions to a ring of CA keys
113 * @dest_keyring: Keyring being linked to.
114 * @type: The type of key being added.
115 * @payload: The payload of the new key.
116 * @trust_keyring: Unused.
118 * Check if the new certificate is a CA. If it is a CA, then mark the new
119 * certificate as being ok to link.
121 * Returns 0 if the new certificate was accepted, -ENOKEY if the
122 * certificate is not a CA. -ENOPKG if the signature uses unsupported
123 * crypto, or some other error if there is a matching certificate but
124 * the signature check cannot be performed.
126 int restrict_link_by_ca(struct key *dest_keyring,
127 const struct key_type *type,
128 const union key_payload *payload,
129 struct key *trust_keyring)
131 const struct public_key *pkey;
133 if (type != &key_type_asymmetric)
136 pkey = payload->data[asym_crypto];
139 if (!test_bit(KEY_EFLAG_CA, &pkey->key_eflags))
141 if (!test_bit(KEY_EFLAG_KEYCERTSIGN, &pkey->key_eflags))
143 if (!IS_ENABLED(CONFIG_INTEGRITY_CA_MACHINE_KEYRING_MAX))
145 if (test_bit(KEY_EFLAG_DIGITALSIG, &pkey->key_eflags))
151 static bool match_either_id(const struct asymmetric_key_id **pair,
152 const struct asymmetric_key_id *single)
154 return (asymmetric_key_id_same(pair[0], single) ||
155 asymmetric_key_id_same(pair[1], single));
158 static int key_or_keyring_common(struct key *dest_keyring,
159 const struct key_type *type,
160 const union key_payload *payload,
161 struct key *trusted, bool check_dest)
163 const struct public_key_signature *sig;
164 struct key *key = NULL;
167 pr_devel("==>%s()\n", __func__);
171 else if (dest_keyring->type != &key_type_keyring)
174 if (!trusted && !check_dest)
177 if (type != &key_type_asymmetric)
180 sig = payload->data[asym_auth];
183 if (!sig->auth_ids[0] && !sig->auth_ids[1] && !sig->auth_ids[2])
187 if (trusted->type == &key_type_keyring) {
188 /* See if we have a key that signed this one. */
189 key = find_asymmetric_key(trusted, sig->auth_ids[0],
191 sig->auth_ids[2], false);
194 } else if (trusted->type == &key_type_asymmetric) {
195 const struct asymmetric_key_id **signer_ids;
197 signer_ids = (const struct asymmetric_key_id **)
198 asymmetric_key_ids(trusted)->id;
201 * The auth_ids come from the candidate key (the
202 * one that is being considered for addition to
203 * dest_keyring) and identify the key that was
206 * The signer_ids are identifiers for the
207 * signing key specified for dest_keyring.
209 * The first auth_id is the preferred id, 2nd and
210 * 3rd are the fallbacks. If exactly one of
211 * auth_ids[0] and auth_ids[1] is present, it may
212 * match either signer_ids[0] or signed_ids[1].
213 * If both are present the first one may match
214 * either signed_id but the second one must match
215 * the second signer_id. If neither of them is
216 * available, auth_ids[2] is matched against
217 * signer_ids[2] as a fallback.
219 if (!sig->auth_ids[0] && !sig->auth_ids[1]) {
220 if (asymmetric_key_id_same(signer_ids[2],
222 key = __key_get(trusted);
224 } else if (!sig->auth_ids[0] || !sig->auth_ids[1]) {
225 const struct asymmetric_key_id *auth_id;
227 auth_id = sig->auth_ids[0] ?: sig->auth_ids[1];
228 if (match_either_id(signer_ids, auth_id))
229 key = __key_get(trusted);
231 } else if (asymmetric_key_id_same(signer_ids[1],
233 match_either_id(signer_ids,
235 key = __key_get(trusted);
242 if (check_dest && !key) {
243 /* See if the destination has a key that signed this one. */
244 key = find_asymmetric_key(dest_keyring, sig->auth_ids[0],
245 sig->auth_ids[1], sig->auth_ids[2],
254 ret = key_validate(key);
256 ret = verify_signature(key, sig);
263 * restrict_link_by_key_or_keyring - Restrict additions to a ring of public
264 * keys using the restrict_key information stored in the ring.
265 * @dest_keyring: Keyring being linked to.
266 * @type: The type of key being added.
267 * @payload: The payload of the new key.
268 * @trusted: A key or ring of keys that can be used to vouch for the new cert.
270 * Check the new certificate only against the key or keys passed in the data
271 * parameter. If one of those is the signing key and validates the new
272 * certificate, then mark the new certificate as being ok to link.
274 * Returns 0 if the new certificate was accepted, -ENOKEY if we
275 * couldn't find a matching parent certificate in the trusted list,
276 * -EKEYREJECTED if the signature check fails, -ENOPKG if the signature uses
277 * unsupported crypto, or some other error if there is a matching certificate
278 * but the signature check cannot be performed.
280 int restrict_link_by_key_or_keyring(struct key *dest_keyring,
281 const struct key_type *type,
282 const union key_payload *payload,
285 return key_or_keyring_common(dest_keyring, type, payload, trusted,
290 * restrict_link_by_key_or_keyring_chain - Restrict additions to a ring of
291 * public keys using the restrict_key information stored in the ring.
292 * @dest_keyring: Keyring being linked to.
293 * @type: The type of key being added.
294 * @payload: The payload of the new key.
295 * @trusted: A key or ring of keys that can be used to vouch for the new cert.
297 * Check the new certificate against the key or keys passed in the data
298 * parameter and against the keys already linked to the destination keyring. If
299 * one of those is the signing key and validates the new certificate, then mark
300 * the new certificate as being ok to link.
302 * Returns 0 if the new certificate was accepted, -ENOKEY if we
303 * couldn't find a matching parent certificate in the trusted list,
304 * -EKEYREJECTED if the signature check fails, -ENOPKG if the signature uses
305 * unsupported crypto, or some other error if there is a matching certificate
306 * but the signature check cannot be performed.
308 int restrict_link_by_key_or_keyring_chain(struct key *dest_keyring,
309 const struct key_type *type,
310 const union key_payload *payload,
313 return key_or_keyring_common(dest_keyring, type, payload, trusted,