1 /* Asymmetric public-key cryptography key type
3 * See Documentation/crypto/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,
60 BUG_ON(!id_0 && !id_1);
70 /* Construct an identifier "id:<keyid>". */
71 p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
73 return ERR_PTR(-ENOMEM);
83 p = bin2hex(p, lookup, len);
86 pr_debug("Look up: \"%s\"\n", req);
88 ref = keyring_search(make_key_ref(keyring, 1),
89 &key_type_asymmetric, req);
91 pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref));
95 switch (PTR_ERR(ref)) {
96 /* Hide some search errors */
100 return ERR_PTR(-ENOKEY);
102 return ERR_CAST(ref);
106 key = key_ref_to_ptr(ref);
108 const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
111 pr_debug("First ID matches, but second is missing\n");
114 if (!asymmetric_key_id_same(id_1, kids->id[1])) {
115 pr_debug("First ID matches, but second does not\n");
120 pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key));
125 return ERR_PTR(-EKEYREJECTED);
127 EXPORT_SYMBOL_GPL(find_asymmetric_key);
130 * asymmetric_key_generate_id: Construct an asymmetric key ID
131 * @val_1: First binary blob
132 * @len_1: Length of first binary blob
133 * @val_2: Second binary blob
134 * @len_2: Length of second binary blob
136 * Construct an asymmetric key ID from a pair of binary blobs.
138 struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
143 struct asymmetric_key_id *kid;
145 kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
148 return ERR_PTR(-ENOMEM);
149 kid->len = len_1 + len_2;
150 memcpy(kid->data, val_1, len_1);
151 memcpy(kid->data + len_1, val_2, len_2);
154 EXPORT_SYMBOL_GPL(asymmetric_key_generate_id);
157 * asymmetric_key_id_same - Return true if two asymmetric keys IDs are the same.
158 * @kid_1, @kid_2: The key IDs to compare
160 bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
161 const struct asymmetric_key_id *kid2)
165 if (kid1->len != kid2->len)
167 return memcmp(kid1->data, kid2->data, kid1->len) == 0;
169 EXPORT_SYMBOL_GPL(asymmetric_key_id_same);
172 * asymmetric_key_id_partial - Return true if two asymmetric keys IDs
174 * @kid_1, @kid_2: The key IDs to compare
176 bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
177 const struct asymmetric_key_id *kid2)
181 if (kid1->len < kid2->len)
183 return memcmp(kid1->data + (kid1->len - kid2->len),
184 kid2->data, kid2->len) == 0;
186 EXPORT_SYMBOL_GPL(asymmetric_key_id_partial);
189 * asymmetric_match_key_ids - Search asymmetric key IDs
190 * @kids: The list of key IDs to check
191 * @match_id: The key ID we're looking for
192 * @match: The match function to use
194 static bool asymmetric_match_key_ids(
195 const struct asymmetric_key_ids *kids,
196 const struct asymmetric_key_id *match_id,
197 bool (*match)(const struct asymmetric_key_id *kid1,
198 const struct asymmetric_key_id *kid2))
202 if (!kids || !match_id)
204 for (i = 0; i < ARRAY_SIZE(kids->id); i++)
205 if (match(kids->id[i], match_id))
210 /* helper function can be called directly with pre-allocated memory */
211 inline int __asymmetric_key_hex_to_key_id(const char *id,
212 struct asymmetric_key_id *match_id,
215 match_id->len = hexlen;
216 return hex2bin(match_id->data, id, hexlen);
220 * asymmetric_key_hex_to_key_id - Convert a hex string into a key ID.
221 * @id: The ID as a hex string.
223 struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
225 struct asymmetric_key_id *match_id;
230 return ERR_PTR(-EINVAL);
231 asciihexlen = strlen(id);
233 return ERR_PTR(-EINVAL);
235 match_id = kmalloc(sizeof(struct asymmetric_key_id) + asciihexlen / 2,
238 return ERR_PTR(-ENOMEM);
239 ret = __asymmetric_key_hex_to_key_id(id, match_id, asciihexlen / 2);
242 return ERR_PTR(-EINVAL);
248 * Match asymmetric keys by an exact match on an ID.
250 static bool asymmetric_key_cmp(const struct key *key,
251 const struct key_match_data *match_data)
253 const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
254 const struct asymmetric_key_id *match_id = match_data->preparsed;
256 return asymmetric_match_key_ids(kids, match_id,
257 asymmetric_key_id_same);
261 * Match asymmetric keys by a partial match on an IDs.
263 static bool asymmetric_key_cmp_partial(const struct key *key,
264 const struct key_match_data *match_data)
266 const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
267 const struct asymmetric_key_id *match_id = match_data->preparsed;
269 return asymmetric_match_key_ids(kids, match_id,
270 asymmetric_key_id_partial);
274 * Preparse the match criterion. If we don't set lookup_type and cmp,
275 * the default will be an exact match on the key description.
277 * There are some specifiers for matching key IDs rather than by the key
280 * "id:<id>" - find a key by partial match on any available ID
281 * "ex:<id>" - find a key by exact match on any available ID
283 * These have to be searched by iteration rather than by direct lookup because
284 * the key is hashed according to its description.
286 static int asymmetric_key_match_preparse(struct key_match_data *match_data)
288 struct asymmetric_key_id *match_id;
289 const char *spec = match_data->raw_data;
291 bool (*cmp)(const struct key *, const struct key_match_data *) =
296 if (spec[0] == 'i' &&
300 cmp = asymmetric_key_cmp_partial;
301 } else if (spec[0] == 'e' &&
309 match_id = asymmetric_key_hex_to_key_id(id);
310 if (IS_ERR(match_id))
311 return PTR_ERR(match_id);
313 match_data->preparsed = match_id;
314 match_data->cmp = cmp;
315 match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
323 * Free the preparsed the match criterion.
325 static void asymmetric_key_match_free(struct key_match_data *match_data)
327 kfree(match_data->preparsed);
331 * Describe the asymmetric key
333 static void asymmetric_key_describe(const struct key *key, struct seq_file *m)
335 const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
336 const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
337 const struct asymmetric_key_id *kid;
338 const unsigned char *p;
341 seq_puts(m, key->description);
345 subtype->describe(key, m);
347 if (kids && kids->id[1]) {
356 seq_printf(m, "%*phN", n, p);
360 /* put something here to indicate the key's capabilities */
366 * Preparse a asymmetric payload to get format the contents appropriately for the
367 * internal payload to cut down on the number of scans of the data performed.
369 * We also generate a proposed description from the contents of the key that
370 * can be used to name the key if the user doesn't want to provide one.
372 static int asymmetric_key_preparse(struct key_preparsed_payload *prep)
374 struct asymmetric_key_parser *parser;
377 pr_devel("==>%s()\n", __func__);
379 if (prep->datalen == 0)
382 down_read(&asymmetric_key_parsers_sem);
385 list_for_each_entry(parser, &asymmetric_key_parsers, link) {
386 pr_debug("Trying parser '%s'\n", parser->name);
388 ret = parser->parse(prep);
389 if (ret != -EBADMSG) {
390 pr_debug("Parser recognised the format (ret %d)\n",
396 up_read(&asymmetric_key_parsers_sem);
397 pr_devel("<==%s() = %d\n", __func__, ret);
402 * Clean up the key ID list
404 static void asymmetric_key_free_kids(struct asymmetric_key_ids *kids)
409 for (i = 0; i < ARRAY_SIZE(kids->id); i++)
416 * Clean up the preparse data
418 static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
420 struct asymmetric_key_subtype *subtype = prep->payload.data[asym_subtype];
421 struct asymmetric_key_ids *kids = prep->payload.data[asym_key_ids];
423 pr_devel("==>%s()\n", __func__);
426 subtype->destroy(prep->payload.data[asym_crypto],
427 prep->payload.data[asym_auth]);
428 module_put(subtype->owner);
430 asymmetric_key_free_kids(kids);
431 kfree(prep->description);
435 * dispose of the data dangling from the corpse of a asymmetric key
437 static void asymmetric_key_destroy(struct key *key)
439 struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
440 struct asymmetric_key_ids *kids = key->payload.data[asym_key_ids];
441 void *data = key->payload.data[asym_crypto];
442 void *auth = key->payload.data[asym_auth];
444 key->payload.data[asym_crypto] = NULL;
445 key->payload.data[asym_subtype] = NULL;
446 key->payload.data[asym_key_ids] = NULL;
447 key->payload.data[asym_auth] = NULL;
450 subtype->destroy(data, auth);
451 module_put(subtype->owner);
454 asymmetric_key_free_kids(kids);
457 static struct key_restriction *asymmetric_restriction_alloc(
458 key_restrict_link_func_t check,
461 struct key_restriction *keyres =
462 kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
465 return ERR_PTR(-ENOMEM);
467 keyres->check = check;
469 keyres->keytype = &key_type_asymmetric;
475 * look up keyring restrict functions for asymmetric keys
477 static struct key_restriction *asymmetric_lookup_restriction(
478 const char *restriction)
480 char *restrict_method;
483 struct key_restriction *ret = ERR_PTR(-EINVAL);
485 if (strcmp("builtin_trusted", restriction) == 0)
486 return asymmetric_restriction_alloc(
487 restrict_link_by_builtin_trusted, NULL);
489 if (strcmp("builtin_and_secondary_trusted", restriction) == 0)
490 return asymmetric_restriction_alloc(
491 restrict_link_by_builtin_and_secondary_trusted, NULL);
493 parse_buf = kstrndup(restriction, PAGE_SIZE, GFP_KERNEL);
495 return ERR_PTR(-ENOMEM);
498 restrict_method = strsep(&next, ":");
500 if ((strcmp(restrict_method, "key_or_keyring") == 0) && next) {
504 key_restrict_link_func_t link_fn =
505 restrict_link_by_key_or_keyring;
506 bool allow_null_key = false;
508 key_text = strsep(&next, ":");
511 if (strcmp(next, "chain") != 0)
514 link_fn = restrict_link_by_key_or_keyring_chain;
515 allow_null_key = true;
518 if (kstrtos32(key_text, 0, &serial) < 0)
521 if ((serial == 0) && allow_null_key) {
524 key = key_lookup(serial);
531 ret = asymmetric_restriction_alloc(link_fn, key);
541 struct key_type key_type_asymmetric = {
542 .name = "asymmetric",
543 .preparse = asymmetric_key_preparse,
544 .free_preparse = asymmetric_key_free_preparse,
545 .instantiate = generic_key_instantiate,
546 .match_preparse = asymmetric_key_match_preparse,
547 .match_free = asymmetric_key_match_free,
548 .destroy = asymmetric_key_destroy,
549 .describe = asymmetric_key_describe,
550 .lookup_restriction = asymmetric_lookup_restriction,
552 EXPORT_SYMBOL_GPL(key_type_asymmetric);
555 * register_asymmetric_key_parser - Register a asymmetric key blob parser
556 * @parser: The parser to register
558 int register_asymmetric_key_parser(struct asymmetric_key_parser *parser)
560 struct asymmetric_key_parser *cursor;
563 down_write(&asymmetric_key_parsers_sem);
565 list_for_each_entry(cursor, &asymmetric_key_parsers, link) {
566 if (strcmp(cursor->name, parser->name) == 0) {
567 pr_err("Asymmetric key parser '%s' already registered\n",
574 list_add_tail(&parser->link, &asymmetric_key_parsers);
576 pr_notice("Asymmetric key parser '%s' registered\n", parser->name);
580 up_write(&asymmetric_key_parsers_sem);
583 EXPORT_SYMBOL_GPL(register_asymmetric_key_parser);
586 * unregister_asymmetric_key_parser - Unregister a asymmetric key blob parser
587 * @parser: The parser to unregister
589 void unregister_asymmetric_key_parser(struct asymmetric_key_parser *parser)
591 down_write(&asymmetric_key_parsers_sem);
592 list_del(&parser->link);
593 up_write(&asymmetric_key_parsers_sem);
595 pr_notice("Asymmetric key parser '%s' unregistered\n", parser->name);
597 EXPORT_SYMBOL_GPL(unregister_asymmetric_key_parser);
602 static int __init asymmetric_key_init(void)
604 return register_key_type(&key_type_asymmetric);
607 static void __exit asymmetric_key_cleanup(void)
609 unregister_key_type(&key_type_asymmetric);
612 module_init(asymmetric_key_init);
613 module_exit(asymmetric_key_cleanup);