1 /* Asymmetric public-key cryptography key type
3 * See Documentation/security/asymmetric-keys.txt
5 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
6 * Written by David Howells (dhowells@redhat.com)
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public Licence
10 * as published by the Free Software Foundation; either version
11 * 2 of the Licence, or (at your option) any later version.
13 #include <keys/asymmetric-subtype.h>
14 #include <keys/asymmetric-parser.h>
15 #include <crypto/public_key.h>
16 #include <linux/seq_file.h>
17 #include <linux/module.h>
18 #include <linux/slab.h>
19 #include <linux/ctype.h>
20 #include <keys/system_keyring.h>
21 #include "asymmetric_keys.h"
23 MODULE_LICENSE("GPL");
25 const char *const key_being_used_for[NR__KEY_BEING_USED_FOR] = {
26 [VERIFYING_MODULE_SIGNATURE] = "mod sig",
27 [VERIFYING_FIRMWARE_SIGNATURE] = "firmware sig",
28 [VERIFYING_KEXEC_PE_SIGNATURE] = "kexec PE sig",
29 [VERIFYING_KEY_SIGNATURE] = "key sig",
30 [VERIFYING_KEY_SELF_SIGNATURE] = "key self sig",
31 [VERIFYING_UNSPECIFIED_SIGNATURE] = "unspec sig",
33 EXPORT_SYMBOL_GPL(key_being_used_for);
35 static LIST_HEAD(asymmetric_key_parsers);
36 static DECLARE_RWSEM(asymmetric_key_parsers_sem);
39 * find_asymmetric_key - Find a key by ID.
40 * @keyring: The keys to search.
41 * @id_0: The first ID to look for or NULL.
42 * @id_1: The second ID to look for or NULL.
43 * @partial: Use partial match if true, exact if false.
45 * Find a key in the given keyring by identifier. The preferred identifier is
46 * the id_0 and the fallback identifier is the id_1. If both are given, the
47 * lookup is by the former, but the latter must also match.
49 struct key *find_asymmetric_key(struct key *keyring,
50 const struct asymmetric_key_id *id_0,
51 const struct asymmetric_key_id *id_1,
68 /* Construct an identifier "id:<keyid>". */
69 p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
71 return ERR_PTR(-ENOMEM);
81 p = bin2hex(p, lookup, len);
84 pr_debug("Look up: \"%s\"\n", req);
86 ref = keyring_search(make_key_ref(keyring, 1),
87 &key_type_asymmetric, req);
89 pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref));
93 switch (PTR_ERR(ref)) {
94 /* Hide some search errors */
98 return ERR_PTR(-ENOKEY);
100 return ERR_CAST(ref);
104 key = key_ref_to_ptr(ref);
106 const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
109 pr_debug("First ID matches, but second is missing\n");
112 if (!asymmetric_key_id_same(id_1, kids->id[1])) {
113 pr_debug("First ID matches, but second does not\n");
118 pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key));
123 return ERR_PTR(-EKEYREJECTED);
125 EXPORT_SYMBOL_GPL(find_asymmetric_key);
128 * asymmetric_key_generate_id: Construct an asymmetric key ID
129 * @val_1: First binary blob
130 * @len_1: Length of first binary blob
131 * @val_2: Second binary blob
132 * @len_2: Length of second binary blob
134 * Construct an asymmetric key ID from a pair of binary blobs.
136 struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
141 struct asymmetric_key_id *kid;
143 kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
146 return ERR_PTR(-ENOMEM);
147 kid->len = len_1 + len_2;
148 memcpy(kid->data, val_1, len_1);
149 memcpy(kid->data + len_1, val_2, len_2);
152 EXPORT_SYMBOL_GPL(asymmetric_key_generate_id);
155 * asymmetric_key_id_same - Return true if two asymmetric keys IDs are the same.
156 * @kid_1, @kid_2: The key IDs to compare
158 bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
159 const struct asymmetric_key_id *kid2)
163 if (kid1->len != kid2->len)
165 return memcmp(kid1->data, kid2->data, kid1->len) == 0;
167 EXPORT_SYMBOL_GPL(asymmetric_key_id_same);
170 * asymmetric_key_id_partial - Return true if two asymmetric keys IDs
172 * @kid_1, @kid_2: The key IDs to compare
174 bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
175 const struct asymmetric_key_id *kid2)
179 if (kid1->len < kid2->len)
181 return memcmp(kid1->data + (kid1->len - kid2->len),
182 kid2->data, kid2->len) == 0;
184 EXPORT_SYMBOL_GPL(asymmetric_key_id_partial);
187 * asymmetric_match_key_ids - Search asymmetric key IDs
188 * @kids: The list of key IDs to check
189 * @match_id: The key ID we're looking for
190 * @match: The match function to use
192 static bool asymmetric_match_key_ids(
193 const struct asymmetric_key_ids *kids,
194 const struct asymmetric_key_id *match_id,
195 bool (*match)(const struct asymmetric_key_id *kid1,
196 const struct asymmetric_key_id *kid2))
200 if (!kids || !match_id)
202 for (i = 0; i < ARRAY_SIZE(kids->id); i++)
203 if (match(kids->id[i], match_id))
208 /* helper function can be called directly with pre-allocated memory */
209 inline int __asymmetric_key_hex_to_key_id(const char *id,
210 struct asymmetric_key_id *match_id,
213 match_id->len = hexlen;
214 return hex2bin(match_id->data, id, hexlen);
218 * asymmetric_key_hex_to_key_id - Convert a hex string into a key ID.
219 * @id: The ID as a hex string.
221 struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
223 struct asymmetric_key_id *match_id;
228 return ERR_PTR(-EINVAL);
229 asciihexlen = strlen(id);
231 return ERR_PTR(-EINVAL);
233 match_id = kmalloc(sizeof(struct asymmetric_key_id) + asciihexlen / 2,
236 return ERR_PTR(-ENOMEM);
237 ret = __asymmetric_key_hex_to_key_id(id, match_id, asciihexlen / 2);
240 return ERR_PTR(-EINVAL);
246 * Match asymmetric keys by an exact match on an ID.
248 static bool asymmetric_key_cmp(const struct key *key,
249 const struct key_match_data *match_data)
251 const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
252 const struct asymmetric_key_id *match_id = match_data->preparsed;
254 return asymmetric_match_key_ids(kids, match_id,
255 asymmetric_key_id_same);
259 * Match asymmetric keys by a partial match on an IDs.
261 static bool asymmetric_key_cmp_partial(const struct key *key,
262 const struct key_match_data *match_data)
264 const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
265 const struct asymmetric_key_id *match_id = match_data->preparsed;
267 return asymmetric_match_key_ids(kids, match_id,
268 asymmetric_key_id_partial);
272 * Preparse the match criterion. If we don't set lookup_type and cmp,
273 * the default will be an exact match on the key description.
275 * There are some specifiers for matching key IDs rather than by the key
278 * "id:<id>" - find a key by partial match on any available ID
279 * "ex:<id>" - find a key by exact match on any available ID
281 * These have to be searched by iteration rather than by direct lookup because
282 * the key is hashed according to its description.
284 static int asymmetric_key_match_preparse(struct key_match_data *match_data)
286 struct asymmetric_key_id *match_id;
287 const char *spec = match_data->raw_data;
289 bool (*cmp)(const struct key *, const struct key_match_data *) =
294 if (spec[0] == 'i' &&
298 cmp = asymmetric_key_cmp_partial;
299 } else if (spec[0] == 'e' &&
307 match_id = asymmetric_key_hex_to_key_id(id);
308 if (IS_ERR(match_id))
309 return PTR_ERR(match_id);
311 match_data->preparsed = match_id;
312 match_data->cmp = cmp;
313 match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
321 * Free the preparsed the match criterion.
323 static void asymmetric_key_match_free(struct key_match_data *match_data)
325 kfree(match_data->preparsed);
329 * Describe the asymmetric key
331 static void asymmetric_key_describe(const struct key *key, struct seq_file *m)
333 const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
334 const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
335 const struct asymmetric_key_id *kid;
336 const unsigned char *p;
339 seq_puts(m, key->description);
343 subtype->describe(key, m);
345 if (kids && kids->id[1]) {
354 seq_printf(m, "%*phN", n, p);
358 /* put something here to indicate the key's capabilities */
364 * Preparse a asymmetric payload to get format the contents appropriately for the
365 * internal payload to cut down on the number of scans of the data performed.
367 * We also generate a proposed description from the contents of the key that
368 * can be used to name the key if the user doesn't want to provide one.
370 static int asymmetric_key_preparse(struct key_preparsed_payload *prep)
372 struct asymmetric_key_parser *parser;
375 pr_devel("==>%s()\n", __func__);
377 if (prep->datalen == 0)
380 down_read(&asymmetric_key_parsers_sem);
383 list_for_each_entry(parser, &asymmetric_key_parsers, link) {
384 pr_debug("Trying parser '%s'\n", parser->name);
386 ret = parser->parse(prep);
387 if (ret != -EBADMSG) {
388 pr_debug("Parser recognised the format (ret %d)\n",
394 up_read(&asymmetric_key_parsers_sem);
395 pr_devel("<==%s() = %d\n", __func__, ret);
400 * Clean up the key ID list
402 static void asymmetric_key_free_kids(struct asymmetric_key_ids *kids)
407 for (i = 0; i < ARRAY_SIZE(kids->id); i++)
414 * Clean up the preparse data
416 static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
418 struct asymmetric_key_subtype *subtype = prep->payload.data[asym_subtype];
419 struct asymmetric_key_ids *kids = prep->payload.data[asym_key_ids];
421 pr_devel("==>%s()\n", __func__);
424 subtype->destroy(prep->payload.data[asym_crypto],
425 prep->payload.data[asym_auth]);
426 module_put(subtype->owner);
428 asymmetric_key_free_kids(kids);
429 kfree(prep->description);
433 * dispose of the data dangling from the corpse of a asymmetric key
435 static void asymmetric_key_destroy(struct key *key)
437 struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
438 struct asymmetric_key_ids *kids = key->payload.data[asym_key_ids];
439 void *data = key->payload.data[asym_crypto];
440 void *auth = key->payload.data[asym_auth];
442 key->payload.data[asym_crypto] = NULL;
443 key->payload.data[asym_subtype] = NULL;
444 key->payload.data[asym_key_ids] = NULL;
445 key->payload.data[asym_auth] = NULL;
448 subtype->destroy(data, auth);
449 module_put(subtype->owner);
452 asymmetric_key_free_kids(kids);
455 static struct key_restriction *asymmetric_restriction_alloc(
456 key_restrict_link_func_t check,
459 struct key_restriction *keyres =
460 kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
463 return ERR_PTR(-ENOMEM);
465 keyres->check = check;
467 keyres->keytype = &key_type_asymmetric;
473 * look up keyring restrict functions for asymmetric keys
475 static struct key_restriction *asymmetric_lookup_restriction(
476 const char *restriction)
478 char *restrict_method;
481 struct key_restriction *ret = ERR_PTR(-EINVAL);
483 if (strcmp("builtin_trusted", restriction) == 0)
484 return asymmetric_restriction_alloc(
485 restrict_link_by_builtin_trusted, NULL);
487 if (strcmp("builtin_and_secondary_trusted", restriction) == 0)
488 return asymmetric_restriction_alloc(
489 restrict_link_by_builtin_and_secondary_trusted, NULL);
491 parse_buf = kstrndup(restriction, PAGE_SIZE, GFP_KERNEL);
493 return ERR_PTR(-ENOMEM);
496 restrict_method = strsep(&next, ":");
498 if ((strcmp(restrict_method, "key_or_keyring") == 0) && next) {
502 key_restrict_link_func_t link_fn =
503 restrict_link_by_key_or_keyring;
504 bool allow_null_key = false;
506 key_text = strsep(&next, ":");
509 if (strcmp(next, "chain") != 0)
512 link_fn = restrict_link_by_key_or_keyring_chain;
513 allow_null_key = true;
516 if (kstrtos32(key_text, 0, &serial) < 0)
519 if ((serial == 0) && allow_null_key) {
522 key = key_lookup(serial);
529 ret = asymmetric_restriction_alloc(link_fn, key);
539 struct key_type key_type_asymmetric = {
540 .name = "asymmetric",
541 .preparse = asymmetric_key_preparse,
542 .free_preparse = asymmetric_key_free_preparse,
543 .instantiate = generic_key_instantiate,
544 .match_preparse = asymmetric_key_match_preparse,
545 .match_free = asymmetric_key_match_free,
546 .destroy = asymmetric_key_destroy,
547 .describe = asymmetric_key_describe,
548 .lookup_restriction = asymmetric_lookup_restriction,
550 EXPORT_SYMBOL_GPL(key_type_asymmetric);
553 * register_asymmetric_key_parser - Register a asymmetric key blob parser
554 * @parser: The parser to register
556 int register_asymmetric_key_parser(struct asymmetric_key_parser *parser)
558 struct asymmetric_key_parser *cursor;
561 down_write(&asymmetric_key_parsers_sem);
563 list_for_each_entry(cursor, &asymmetric_key_parsers, link) {
564 if (strcmp(cursor->name, parser->name) == 0) {
565 pr_err("Asymmetric key parser '%s' already registered\n",
572 list_add_tail(&parser->link, &asymmetric_key_parsers);
574 pr_notice("Asymmetric key parser '%s' registered\n", parser->name);
578 up_write(&asymmetric_key_parsers_sem);
581 EXPORT_SYMBOL_GPL(register_asymmetric_key_parser);
584 * unregister_asymmetric_key_parser - Unregister a asymmetric key blob parser
585 * @parser: The parser to unregister
587 void unregister_asymmetric_key_parser(struct asymmetric_key_parser *parser)
589 down_write(&asymmetric_key_parsers_sem);
590 list_del(&parser->link);
591 up_write(&asymmetric_key_parsers_sem);
593 pr_notice("Asymmetric key parser '%s' unregistered\n", parser->name);
595 EXPORT_SYMBOL_GPL(unregister_asymmetric_key_parser);
600 static int __init asymmetric_key_init(void)
602 return register_key_type(&key_type_asymmetric);
605 static void __exit asymmetric_key_cleanup(void)
607 unregister_key_type(&key_type_asymmetric);
610 module_init(asymmetric_key_init);
611 module_exit(asymmetric_key_cleanup);