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David Howells69664cf2008-04-29 01:01:31 -07001/* Keyring handling
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 *
David Howells69664cf2008-04-29 01:01:31 -07003 * Copyright (C) 2004-2005, 2008 Red Hat, Inc. All Rights Reserved.
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 * 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 License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/sched.h>
15#include <linux/slab.h>
David Howells29db9192005-10-30 15:02:44 -080016#include <linux/security.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/seq_file.h>
18#include <linux/err.h>
David Howellse9e349b2008-11-14 10:39:13 +110019#include <keys/keyring-type.h>
Chihau Chau512ea3b2010-03-08 20:11:34 -030020#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include "internal.h"
22
David Howellsf0641cb2010-04-30 14:32:18 +010023#define rcu_dereference_locked_keyring(keyring) \
24 (rcu_dereference_protected( \
25 (keyring)->payload.subscriptions, \
26 rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem)))
27
David Howellsceb73c12011-01-25 16:34:28 +000028#define KEY_LINK_FIXQUOTA 1UL
29
Linus Torvalds1da177e2005-04-16 15:20:36 -070030/*
David Howells973c9f42011-01-20 16:38:33 +000031 * When plumbing the depths of the key tree, this sets a hard limit
32 * set on how deep we're willing to go.
Linus Torvalds1da177e2005-04-16 15:20:36 -070033 */
34#define KEYRING_SEARCH_MAX_DEPTH 6
35
36/*
David Howells973c9f42011-01-20 16:38:33 +000037 * We keep all named keyrings in a hash to speed looking them up.
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 */
39#define KEYRING_NAME_HASH_SIZE (1 << 5)
40
41static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE];
42static DEFINE_RWLOCK(keyring_name_lock);
43
44static inline unsigned keyring_hash(const char *desc)
45{
46 unsigned bucket = 0;
47
48 for (; *desc; desc++)
Justin P. Mattockc5b60b52010-04-21 00:02:11 -070049 bucket += (unsigned char)*desc;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
51 return bucket & (KEYRING_NAME_HASH_SIZE - 1);
52}
53
54/*
David Howells973c9f42011-01-20 16:38:33 +000055 * The keyring key type definition. Keyrings are simply keys of this type and
56 * can be treated as ordinary keys in addition to having their own special
57 * operations.
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 */
59static int keyring_instantiate(struct key *keyring,
60 const void *data, size_t datalen);
Linus Torvalds1da177e2005-04-16 15:20:36 -070061static int keyring_match(const struct key *keyring, const void *criterion);
David Howells31204ed2006-06-26 00:24:51 -070062static void keyring_revoke(struct key *keyring);
Linus Torvalds1da177e2005-04-16 15:20:36 -070063static void keyring_destroy(struct key *keyring);
64static void keyring_describe(const struct key *keyring, struct seq_file *m);
65static long keyring_read(const struct key *keyring,
66 char __user *buffer, size_t buflen);
67
68struct key_type key_type_keyring = {
69 .name = "keyring",
70 .def_datalen = sizeof(struct keyring_list),
71 .instantiate = keyring_instantiate,
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 .match = keyring_match,
David Howells31204ed2006-06-26 00:24:51 -070073 .revoke = keyring_revoke,
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 .destroy = keyring_destroy,
75 .describe = keyring_describe,
76 .read = keyring_read,
77};
David Howells73182262007-04-26 15:46:23 -070078EXPORT_SYMBOL(key_type_keyring);
79
Linus Torvalds1da177e2005-04-16 15:20:36 -070080/*
David Howells973c9f42011-01-20 16:38:33 +000081 * Semaphore to serialise link/link calls to prevent two link calls in parallel
82 * introducing a cycle.
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 */
Adrian Bunk1ae8f402006-01-06 00:11:25 -080084static DECLARE_RWSEM(keyring_serialise_link_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
Linus Torvalds1da177e2005-04-16 15:20:36 -070086/*
David Howells973c9f42011-01-20 16:38:33 +000087 * Publish the name of a keyring so that it can be found by name (if it has
88 * one).
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 */
David Howells69664cf2008-04-29 01:01:31 -070090static void keyring_publish_name(struct key *keyring)
Linus Torvalds1da177e2005-04-16 15:20:36 -070091{
92 int bucket;
93
94 if (keyring->description) {
95 bucket = keyring_hash(keyring->description);
96
97 write_lock(&keyring_name_lock);
98
99 if (!keyring_name_hash[bucket].next)
100 INIT_LIST_HEAD(&keyring_name_hash[bucket]);
101
102 list_add_tail(&keyring->type_data.link,
103 &keyring_name_hash[bucket]);
104
105 write_unlock(&keyring_name_lock);
106 }
David Howellsa8b17ed2011-01-20 16:38:27 +0000107}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109/*
David Howells973c9f42011-01-20 16:38:33 +0000110 * Initialise a keyring.
111 *
112 * Returns 0 on success, -EINVAL if given any data.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 */
114static int keyring_instantiate(struct key *keyring,
115 const void *data, size_t datalen)
116{
117 int ret;
118
119 ret = -EINVAL;
120 if (datalen == 0) {
121 /* make the keyring available by name if it has one */
122 keyring_publish_name(keyring);
123 ret = 0;
124 }
125
126 return ret;
David Howellsa8b17ed2011-01-20 16:38:27 +0000127}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129/*
David Howells973c9f42011-01-20 16:38:33 +0000130 * Match keyrings on their name
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 */
132static int keyring_match(const struct key *keyring, const void *description)
133{
134 return keyring->description &&
135 strcmp(keyring->description, description) == 0;
David Howellsa8b17ed2011-01-20 16:38:27 +0000136}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138/*
David Howells973c9f42011-01-20 16:38:33 +0000139 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
140 * and dispose of its data.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 */
142static void keyring_destroy(struct key *keyring)
143{
144 struct keyring_list *klist;
145 int loop;
146
147 if (keyring->description) {
148 write_lock(&keyring_name_lock);
David Howells94efe722005-08-04 13:07:07 -0700149
150 if (keyring->type_data.link.next != NULL &&
151 !list_empty(&keyring->type_data.link))
152 list_del(&keyring->type_data.link);
153
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 write_unlock(&keyring_name_lock);
155 }
156
Paul E. McKenneye7b0a612010-02-22 17:04:56 -0800157 klist = rcu_dereference_check(keyring->payload.subscriptions,
158 rcu_read_lock_held() ||
159 atomic_read(&keyring->usage) == 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 if (klist) {
161 for (loop = klist->nkeys - 1; loop >= 0; loop--)
162 key_put(klist->keys[loop]);
163 kfree(klist);
164 }
David Howellsa8b17ed2011-01-20 16:38:27 +0000165}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167/*
David Howells973c9f42011-01-20 16:38:33 +0000168 * Describe a keyring for /proc.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 */
170static void keyring_describe(const struct key *keyring, struct seq_file *m)
171{
172 struct keyring_list *klist;
173
wzt.wzt@gmail.comc8563472010-03-04 21:26:23 +0800174 if (keyring->description)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 seq_puts(m, keyring->description);
wzt.wzt@gmail.comc8563472010-03-04 21:26:23 +0800176 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 seq_puts(m, "[anon]");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178
David Howells76d8aea2005-06-23 22:00:49 -0700179 rcu_read_lock();
180 klist = rcu_dereference(keyring->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 if (klist)
182 seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
183 else
184 seq_puts(m, ": empty");
David Howells76d8aea2005-06-23 22:00:49 -0700185 rcu_read_unlock();
David Howellsa8b17ed2011-01-20 16:38:27 +0000186}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188/*
David Howells973c9f42011-01-20 16:38:33 +0000189 * Read a list of key IDs from the keyring's contents in binary form
190 *
191 * The keyring's semaphore is read-locked by the caller.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 */
193static long keyring_read(const struct key *keyring,
194 char __user *buffer, size_t buflen)
195{
196 struct keyring_list *klist;
197 struct key *key;
198 size_t qty, tmp;
199 int loop, ret;
200
201 ret = 0;
David Howellsf0641cb2010-04-30 14:32:18 +0100202 klist = rcu_dereference_locked_keyring(keyring);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 if (klist) {
204 /* calculate how much data we could return */
205 qty = klist->nkeys * sizeof(key_serial_t);
206
207 if (buffer && buflen > 0) {
208 if (buflen > qty)
209 buflen = qty;
210
211 /* copy the IDs of the subscribed keys into the
212 * buffer */
213 ret = -EFAULT;
214
215 for (loop = 0; loop < klist->nkeys; loop++) {
216 key = klist->keys[loop];
217
218 tmp = sizeof(key_serial_t);
219 if (tmp > buflen)
220 tmp = buflen;
221
222 if (copy_to_user(buffer,
223 &key->serial,
224 tmp) != 0)
225 goto error;
226
227 buflen -= tmp;
228 if (buflen == 0)
229 break;
230 buffer += tmp;
231 }
232 }
233
234 ret = qty;
235 }
236
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700237error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 return ret;
David Howellsa8b17ed2011-01-20 16:38:27 +0000239}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241/*
David Howells973c9f42011-01-20 16:38:33 +0000242 * Allocate a keyring and link into the destination keyring.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 */
244struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
David Howellsd84f4f92008-11-14 10:39:23 +1100245 const struct cred *cred, unsigned long flags,
Michael LeMayd7200242006-06-22 14:47:17 -0700246 struct key *dest)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247{
248 struct key *keyring;
249 int ret;
250
251 keyring = key_alloc(&key_type_keyring, description,
David Howellsd84f4f92008-11-14 10:39:23 +1100252 uid, gid, cred,
David Howells29db9192005-10-30 15:02:44 -0800253 (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
David Howells7e047ef2006-06-26 00:24:50 -0700254 flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255
256 if (!IS_ERR(keyring)) {
David Howells3e301482005-06-23 22:00:56 -0700257 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 if (ret < 0) {
259 key_put(keyring);
260 keyring = ERR_PTR(ret);
261 }
262 }
263
264 return keyring;
David Howellsa8b17ed2011-01-20 16:38:27 +0000265}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266
David Howells973c9f42011-01-20 16:38:33 +0000267/**
268 * keyring_search_aux - Search a keyring tree for a key matching some criteria
269 * @keyring_ref: A pointer to the keyring with possession indicator.
270 * @cred: The credentials to use for permissions checks.
271 * @type: The type of key to search for.
272 * @description: Parameter for @match.
273 * @match: Function to rule on whether or not a key is the one required.
274 *
275 * Search the supplied keyring tree for a key that matches the criteria given.
276 * The root keyring and any linked keyrings must grant Search permission to the
277 * caller to be searchable and keys can only be found if they too grant Search
278 * to the caller. The possession flag on the root keyring pointer controls use
279 * of the possessor bits in permissions checking of the entire tree. In
280 * addition, the LSM gets to forbid keyring searches and key matches.
281 *
282 * The search is performed as a breadth-then-depth search up to the prescribed
283 * limit (KEYRING_SEARCH_MAX_DEPTH).
284 *
285 * Keys are matched to the type provided and are then filtered by the match
286 * function, which is given the description to use in any way it sees fit. The
287 * match function may use any attributes of a key that it wishes to to
288 * determine the match. Normally the match function from the key type would be
289 * used.
290 *
291 * RCU is used to prevent the keyring key lists from disappearing without the
292 * need to take lots of locks.
293 *
294 * Returns a pointer to the found key and increments the key usage count if
295 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
296 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
297 * specified keyring wasn't a keyring.
298 *
299 * In the case of a successful return, the possession attribute from
300 * @keyring_ref is propagated to the returned key reference.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 */
David Howells664cceb2005-09-28 17:03:15 +0100302key_ref_t keyring_search_aux(key_ref_t keyring_ref,
David Howellsd84f4f92008-11-14 10:39:23 +1100303 const struct cred *cred,
David Howells664cceb2005-09-28 17:03:15 +0100304 struct key_type *type,
305 const void *description,
306 key_match_func_t match)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307{
308 struct {
David Howells76d8aea2005-06-23 22:00:49 -0700309 struct keyring_list *keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 int kix;
311 } stack[KEYRING_SEARCH_MAX_DEPTH];
312
313 struct keyring_list *keylist;
314 struct timespec now;
Kevin Coffmandceba992008-04-29 01:01:22 -0700315 unsigned long possessed, kflags;
David Howells664cceb2005-09-28 17:03:15 +0100316 struct key *keyring, *key;
317 key_ref_t key_ref;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 long err;
David Howells76d8aea2005-06-23 22:00:49 -0700319 int sp, kix;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320
David Howells664cceb2005-09-28 17:03:15 +0100321 keyring = key_ref_to_ptr(keyring_ref);
322 possessed = is_key_possessed(keyring_ref);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 key_check(keyring);
324
325 /* top keyring must have search permission to begin the search */
Chihau Chau512ea3b2010-03-08 20:11:34 -0300326 err = key_task_permission(keyring_ref, cred, KEY_SEARCH);
David Howells29db9192005-10-30 15:02:44 -0800327 if (err < 0) {
328 key_ref = ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 goto error;
David Howells29db9192005-10-30 15:02:44 -0800330 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331
David Howells664cceb2005-09-28 17:03:15 +0100332 key_ref = ERR_PTR(-ENOTDIR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 if (keyring->type != &key_type_keyring)
334 goto error;
335
David Howells664cceb2005-09-28 17:03:15 +0100336 rcu_read_lock();
337
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 now = current_kernel_time();
339 err = -EAGAIN;
340 sp = 0;
341
Kevin Coffmandceba992008-04-29 01:01:22 -0700342 /* firstly we should check to see if this top-level keyring is what we
343 * are looking for */
344 key_ref = ERR_PTR(-EAGAIN);
345 kflags = keyring->flags;
346 if (keyring->type == type && match(keyring, description)) {
347 key = keyring;
348
349 /* check it isn't negative and hasn't expired or been
350 * revoked */
351 if (kflags & (1 << KEY_FLAG_REVOKED))
352 goto error_2;
353 if (key->expiry && now.tv_sec >= key->expiry)
354 goto error_2;
David Howellsfdd1b942011-03-07 15:06:09 +0000355 key_ref = ERR_PTR(key->type_data.reject_error);
Kevin Coffmandceba992008-04-29 01:01:22 -0700356 if (kflags & (1 << KEY_FLAG_NEGATIVE))
357 goto error_2;
358 goto found;
359 }
360
361 /* otherwise, the top keyring must not be revoked, expired, or
362 * negatively instantiated if we are to search it */
363 key_ref = ERR_PTR(-EAGAIN);
364 if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) ||
365 (keyring->expiry && now.tv_sec >= keyring->expiry))
366 goto error_2;
367
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 /* start processing a new keyring */
David Howells664cceb2005-09-28 17:03:15 +0100369descend:
David Howells76d8aea2005-06-23 22:00:49 -0700370 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 goto not_this_keyring;
372
David Howells76d8aea2005-06-23 22:00:49 -0700373 keylist = rcu_dereference(keyring->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 if (!keylist)
375 goto not_this_keyring;
376
377 /* iterate through the keys in this keyring first */
378 for (kix = 0; kix < keylist->nkeys; kix++) {
379 key = keylist->keys[kix];
Kevin Coffmandceba992008-04-29 01:01:22 -0700380 kflags = key->flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381
382 /* ignore keys not of this type */
383 if (key->type != type)
384 continue;
385
386 /* skip revoked keys and expired keys */
Kevin Coffmandceba992008-04-29 01:01:22 -0700387 if (kflags & (1 << KEY_FLAG_REVOKED))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 continue;
389
390 if (key->expiry && now.tv_sec >= key->expiry)
391 continue;
392
393 /* keys that don't match */
394 if (!match(key, description))
395 continue;
396
397 /* key must have search permissions */
David Howells29db9192005-10-30 15:02:44 -0800398 if (key_task_permission(make_key_ref(key, possessed),
David Howellsd84f4f92008-11-14 10:39:23 +1100399 cred, KEY_SEARCH) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 continue;
401
Kevin Coffmandceba992008-04-29 01:01:22 -0700402 /* we set a different error code if we pass a negative key */
403 if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
David Howellsfdd1b942011-03-07 15:06:09 +0000404 err = key->type_data.reject_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 continue;
406 }
407
408 goto found;
409 }
410
411 /* search through the keyrings nested in this one */
412 kix = 0;
David Howells664cceb2005-09-28 17:03:15 +0100413ascend:
David Howells76d8aea2005-06-23 22:00:49 -0700414 for (; kix < keylist->nkeys; kix++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 key = keylist->keys[kix];
416 if (key->type != &key_type_keyring)
David Howells76d8aea2005-06-23 22:00:49 -0700417 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418
419 /* recursively search nested keyrings
420 * - only search keyrings for which we have search permission
421 */
422 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
David Howells76d8aea2005-06-23 22:00:49 -0700423 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424
David Howells0f6ed7c2005-11-07 00:59:30 -0800425 if (key_task_permission(make_key_ref(key, possessed),
David Howellsd84f4f92008-11-14 10:39:23 +1100426 cred, KEY_SEARCH) < 0)
David Howells76d8aea2005-06-23 22:00:49 -0700427 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428
429 /* stack the current position */
David Howells76d8aea2005-06-23 22:00:49 -0700430 stack[sp].keylist = keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 stack[sp].kix = kix;
432 sp++;
433
434 /* begin again with the new keyring */
435 keyring = key;
436 goto descend;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 }
438
439 /* the keyring we're looking at was disqualified or didn't contain a
440 * matching key */
David Howells664cceb2005-09-28 17:03:15 +0100441not_this_keyring:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 if (sp > 0) {
443 /* resume the processing of a keyring higher up in the tree */
444 sp--;
David Howells76d8aea2005-06-23 22:00:49 -0700445 keylist = stack[sp].keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446 kix = stack[sp].kix + 1;
447 goto ascend;
448 }
449
David Howells664cceb2005-09-28 17:03:15 +0100450 key_ref = ERR_PTR(err);
451 goto error_2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452
453 /* we found a viable match */
David Howells664cceb2005-09-28 17:03:15 +0100454found:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 atomic_inc(&key->usage);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 key_check(key);
David Howells664cceb2005-09-28 17:03:15 +0100457 key_ref = make_key_ref(key, possessed);
458error_2:
David Howells76d8aea2005-06-23 22:00:49 -0700459 rcu_read_unlock();
David Howells664cceb2005-09-28 17:03:15 +0100460error:
461 return key_ref;
David Howellsa8b17ed2011-01-20 16:38:27 +0000462}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463
David Howells973c9f42011-01-20 16:38:33 +0000464/**
465 * keyring_search - Search the supplied keyring tree for a matching key
466 * @keyring: The root of the keyring tree to be searched.
467 * @type: The type of keyring we want to find.
468 * @description: The name of the keyring we want to find.
469 *
470 * As keyring_search_aux() above, but using the current task's credentials and
471 * type's default matching function.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 */
David Howells664cceb2005-09-28 17:03:15 +0100473key_ref_t keyring_search(key_ref_t keyring,
474 struct key_type *type,
475 const char *description)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476{
David Howells3e301482005-06-23 22:00:56 -0700477 if (!type->match)
478 return ERR_PTR(-ENOKEY);
479
David Howellsd84f4f92008-11-14 10:39:23 +1100480 return keyring_search_aux(keyring, current->cred,
David Howells3e301482005-06-23 22:00:56 -0700481 type, description, type->match);
David Howellsa8b17ed2011-01-20 16:38:27 +0000482}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483EXPORT_SYMBOL(keyring_search);
484
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485/*
David Howells973c9f42011-01-20 16:38:33 +0000486 * Search the given keyring only (no recursion).
487 *
488 * The caller must guarantee that the keyring is a keyring and that the
489 * permission is granted to search the keyring as no check is made here.
490 *
491 * RCU is used to make it unnecessary to lock the keyring key list here.
492 *
493 * Returns a pointer to the found key with usage count incremented if
494 * successful and returns -ENOKEY if not found. Revoked keys and keys not
495 * providing the requested permission are skipped over.
496 *
497 * If successful, the possession indicator is propagated from the keyring ref
498 * to the returned key reference.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 */
David Howells664cceb2005-09-28 17:03:15 +0100500key_ref_t __keyring_search_one(key_ref_t keyring_ref,
501 const struct key_type *ktype,
502 const char *description,
503 key_perm_t perm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504{
505 struct keyring_list *klist;
David Howells664cceb2005-09-28 17:03:15 +0100506 unsigned long possessed;
507 struct key *keyring, *key;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 int loop;
509
David Howells664cceb2005-09-28 17:03:15 +0100510 keyring = key_ref_to_ptr(keyring_ref);
511 possessed = is_key_possessed(keyring_ref);
512
David Howells76d8aea2005-06-23 22:00:49 -0700513 rcu_read_lock();
514
515 klist = rcu_dereference(keyring->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 if (klist) {
517 for (loop = 0; loop < klist->nkeys; loop++) {
518 key = klist->keys[loop];
519
520 if (key->type == ktype &&
David Howells3e301482005-06-23 22:00:56 -0700521 (!key->type->match ||
522 key->type->match(key, description)) &&
David Howells664cceb2005-09-28 17:03:15 +0100523 key_permission(make_key_ref(key, possessed),
David Howellsdb1d1d52005-12-01 00:51:18 -0800524 perm) == 0 &&
David Howells76d8aea2005-06-23 22:00:49 -0700525 !test_bit(KEY_FLAG_REVOKED, &key->flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 )
527 goto found;
528 }
529 }
530
David Howells664cceb2005-09-28 17:03:15 +0100531 rcu_read_unlock();
532 return ERR_PTR(-ENOKEY);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700534found:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 atomic_inc(&key->usage);
David Howells76d8aea2005-06-23 22:00:49 -0700536 rcu_read_unlock();
David Howells664cceb2005-09-28 17:03:15 +0100537 return make_key_ref(key, possessed);
David Howellsa8b17ed2011-01-20 16:38:27 +0000538}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540/*
David Howells973c9f42011-01-20 16:38:33 +0000541 * Find a keyring with the specified name.
542 *
543 * All named keyrings in the current user namespace are searched, provided they
544 * grant Search permission directly to the caller (unless this check is
545 * skipped). Keyrings whose usage points have reached zero or who have been
546 * revoked are skipped.
547 *
548 * Returns a pointer to the keyring with the keyring's refcount having being
549 * incremented on success. -ENOKEY is returned if a key could not be found.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550 */
David Howells69664cf2008-04-29 01:01:31 -0700551struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552{
553 struct key *keyring;
554 int bucket;
555
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 if (!name)
Toshiyuki Okajimacea7daa2010-04-30 14:32:13 +0100557 return ERR_PTR(-EINVAL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558
559 bucket = keyring_hash(name);
560
561 read_lock(&keyring_name_lock);
562
563 if (keyring_name_hash[bucket].next) {
564 /* search this hash bucket for a keyring with a matching name
565 * that's readable and that hasn't been revoked */
566 list_for_each_entry(keyring,
567 &keyring_name_hash[bucket],
568 type_data.link
569 ) {
Serge E. Hallyn2ea190d2009-02-26 18:27:55 -0600570 if (keyring->user->user_ns != current_user_ns())
571 continue;
572
David Howells76d8aea2005-06-23 22:00:49 -0700573 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 continue;
575
576 if (strcmp(keyring->description, name) != 0)
577 continue;
578
David Howells69664cf2008-04-29 01:01:31 -0700579 if (!skip_perm_check &&
580 key_permission(make_key_ref(keyring, 0),
David Howells0f6ed7c2005-11-07 00:59:30 -0800581 KEY_SEARCH) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 continue;
583
Toshiyuki Okajimacea7daa2010-04-30 14:32:13 +0100584 /* we've got a match but we might end up racing with
585 * key_cleanup() if the keyring is currently 'dead'
586 * (ie. it has a zero usage count) */
587 if (!atomic_inc_not_zero(&keyring->usage))
588 continue;
589 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590 }
591 }
592
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 keyring = ERR_PTR(-ENOKEY);
Toshiyuki Okajimacea7daa2010-04-30 14:32:13 +0100594out:
595 read_unlock(&keyring_name_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596 return keyring;
David Howellsa8b17ed2011-01-20 16:38:27 +0000597}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599/*
David Howells973c9f42011-01-20 16:38:33 +0000600 * See if a cycle will will be created by inserting acyclic tree B in acyclic
601 * tree A at the topmost level (ie: as a direct child of A).
602 *
603 * Since we are adding B to A at the top level, checking for cycles should just
604 * be a matter of seeing if node A is somewhere in tree B.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605 */
606static int keyring_detect_cycle(struct key *A, struct key *B)
607{
608 struct {
David Howells76d8aea2005-06-23 22:00:49 -0700609 struct keyring_list *keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610 int kix;
611 } stack[KEYRING_SEARCH_MAX_DEPTH];
612
613 struct keyring_list *keylist;
614 struct key *subtree, *key;
615 int sp, kix, ret;
616
David Howells76d8aea2005-06-23 22:00:49 -0700617 rcu_read_lock();
618
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619 ret = -EDEADLK;
620 if (A == B)
David Howells76d8aea2005-06-23 22:00:49 -0700621 goto cycle_detected;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622
623 subtree = B;
624 sp = 0;
625
626 /* start processing a new keyring */
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700627descend:
David Howells76d8aea2005-06-23 22:00:49 -0700628 if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 goto not_this_keyring;
630
David Howells76d8aea2005-06-23 22:00:49 -0700631 keylist = rcu_dereference(subtree->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 if (!keylist)
633 goto not_this_keyring;
634 kix = 0;
635
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700636ascend:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 /* iterate through the remaining keys in this keyring */
638 for (; kix < keylist->nkeys; kix++) {
639 key = keylist->keys[kix];
640
641 if (key == A)
642 goto cycle_detected;
643
644 /* recursively check nested keyrings */
645 if (key->type == &key_type_keyring) {
646 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
647 goto too_deep;
648
649 /* stack the current position */
David Howells76d8aea2005-06-23 22:00:49 -0700650 stack[sp].keylist = keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 stack[sp].kix = kix;
652 sp++;
653
654 /* begin again with the new keyring */
655 subtree = key;
656 goto descend;
657 }
658 }
659
660 /* the keyring we're looking at was disqualified or didn't contain a
661 * matching key */
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700662not_this_keyring:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663 if (sp > 0) {
664 /* resume the checking of a keyring higher up in the tree */
665 sp--;
David Howells76d8aea2005-06-23 22:00:49 -0700666 keylist = stack[sp].keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 kix = stack[sp].kix + 1;
668 goto ascend;
669 }
670
671 ret = 0; /* no cycles detected */
672
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700673error:
David Howells76d8aea2005-06-23 22:00:49 -0700674 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 return ret;
676
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700677too_deep:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 ret = -ELOOP;
David Howells76d8aea2005-06-23 22:00:49 -0700679 goto error;
680
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700681cycle_detected:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682 ret = -EDEADLK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 goto error;
David Howellsa8b17ed2011-01-20 16:38:27 +0000684}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685
David Howells76d8aea2005-06-23 22:00:49 -0700686/*
David Howells973c9f42011-01-20 16:38:33 +0000687 * Dispose of a keyring list after the RCU grace period, freeing the unlinked
David Howellscab8eb52006-01-08 01:02:45 -0800688 * key
689 */
690static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
691{
692 struct keyring_list *klist =
693 container_of(rcu, struct keyring_list, rcu);
694
Alexey Dobriyan4be929b2010-05-24 14:33:03 -0700695 if (klist->delkey != USHRT_MAX)
David Howellsf70e2e02010-04-30 14:32:39 +0100696 key_put(klist->keys[klist->delkey]);
David Howellscab8eb52006-01-08 01:02:45 -0800697 kfree(klist);
David Howellsf70e2e02010-04-30 14:32:39 +0100698}
David Howellscab8eb52006-01-08 01:02:45 -0800699
David Howellscab8eb52006-01-08 01:02:45 -0800700/*
David Howells973c9f42011-01-20 16:38:33 +0000701 * Preallocate memory so that a key can be linked into to a keyring.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 */
David Howellsf70e2e02010-04-30 14:32:39 +0100703int __key_link_begin(struct key *keyring, const struct key_type *type,
David Howellsceb73c12011-01-25 16:34:28 +0000704 const char *description, unsigned long *_prealloc)
David Howellsf70e2e02010-04-30 14:32:39 +0100705 __acquires(&keyring->sem)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706{
707 struct keyring_list *klist, *nklist;
David Howellsceb73c12011-01-25 16:34:28 +0000708 unsigned long prealloc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709 unsigned max;
710 size_t size;
David Howellscab8eb52006-01-08 01:02:45 -0800711 int loop, ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712
David Howellsf70e2e02010-04-30 14:32:39 +0100713 kenter("%d,%s,%s,", key_serial(keyring), type->name, description);
714
715 if (keyring->type != &key_type_keyring)
716 return -ENOTDIR;
717
718 down_write(&keyring->sem);
719
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 ret = -EKEYREVOKED;
David Howells76d8aea2005-06-23 22:00:49 -0700721 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
David Howellsf70e2e02010-04-30 14:32:39 +0100722 goto error_krsem;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723
David Howellsf70e2e02010-04-30 14:32:39 +0100724 /* serialise link/link calls to prevent parallel calls causing a cycle
725 * when linking two keyring in opposite orders */
726 if (type == &key_type_keyring)
David Howells553d6032010-04-30 14:32:28 +0100727 down_write(&keyring_serialise_link_sem);
728
David Howellsf70e2e02010-04-30 14:32:39 +0100729 klist = rcu_dereference_locked_keyring(keyring);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730
David Howellscab8eb52006-01-08 01:02:45 -0800731 /* see if there's a matching key we can displace */
David Howellscab8eb52006-01-08 01:02:45 -0800732 if (klist && klist->nkeys > 0) {
David Howellscab8eb52006-01-08 01:02:45 -0800733 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
734 if (klist->keys[loop]->type == type &&
735 strcmp(klist->keys[loop]->description,
David Howellsf70e2e02010-04-30 14:32:39 +0100736 description) == 0
David Howellscab8eb52006-01-08 01:02:45 -0800737 ) {
David Howellsf70e2e02010-04-30 14:32:39 +0100738 /* found a match - we'll replace this one with
739 * the new key */
David Howellscab8eb52006-01-08 01:02:45 -0800740 size = sizeof(struct key *) * klist->maxkeys;
741 size += sizeof(*klist);
742 BUG_ON(size > PAGE_SIZE);
743
744 ret = -ENOMEM;
Eric Sesterhenn48ad5042006-12-06 20:33:47 -0800745 nklist = kmemdup(klist, size, GFP_KERNEL);
David Howellscab8eb52006-01-08 01:02:45 -0800746 if (!nklist)
David Howellsf70e2e02010-04-30 14:32:39 +0100747 goto error_sem;
David Howellscab8eb52006-01-08 01:02:45 -0800748
David Howellsf70e2e02010-04-30 14:32:39 +0100749 /* note replacement slot */
750 klist->delkey = nklist->delkey = loop;
David Howellsceb73c12011-01-25 16:34:28 +0000751 prealloc = (unsigned long)nklist;
David Howellscab8eb52006-01-08 01:02:45 -0800752 goto done;
753 }
754 }
755 }
756
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 /* check that we aren't going to overrun the user's quota */
758 ret = key_payload_reserve(keyring,
759 keyring->datalen + KEYQUOTA_LINK_BYTES);
760 if (ret < 0)
David Howellsf70e2e02010-04-30 14:32:39 +0100761 goto error_sem;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 if (klist && klist->nkeys < klist->maxkeys) {
David Howellsf70e2e02010-04-30 14:32:39 +0100764 /* there's sufficient slack space to append directly */
765 nklist = NULL;
David Howellsceb73c12011-01-25 16:34:28 +0000766 prealloc = KEY_LINK_FIXQUOTA;
Chihau Chau512ea3b2010-03-08 20:11:34 -0300767 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 /* grow the key list */
769 max = 4;
770 if (klist)
771 max += klist->maxkeys;
772
773 ret = -ENFILE;
Alexey Dobriyan4be929b2010-05-24 14:33:03 -0700774 if (max > USHRT_MAX - 1)
David Howellsf70e2e02010-04-30 14:32:39 +0100775 goto error_quota;
David Howellsa4014d82005-07-07 17:57:03 -0700776 size = sizeof(*klist) + sizeof(struct key *) * max;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 if (size > PAGE_SIZE)
David Howellsf70e2e02010-04-30 14:32:39 +0100778 goto error_quota;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779
780 ret = -ENOMEM;
781 nklist = kmalloc(size, GFP_KERNEL);
782 if (!nklist)
David Howellsf70e2e02010-04-30 14:32:39 +0100783 goto error_quota;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784
David Howellsf70e2e02010-04-30 14:32:39 +0100785 nklist->maxkeys = max;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 if (klist) {
David Howellsf70e2e02010-04-30 14:32:39 +0100787 memcpy(nklist->keys, klist->keys,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 sizeof(struct key *) * klist->nkeys);
David Howellsf70e2e02010-04-30 14:32:39 +0100789 nklist->delkey = klist->nkeys;
790 nklist->nkeys = klist->nkeys + 1;
Alexey Dobriyan4be929b2010-05-24 14:33:03 -0700791 klist->delkey = USHRT_MAX;
David Howellsf70e2e02010-04-30 14:32:39 +0100792 } else {
793 nklist->nkeys = 1;
794 nklist->delkey = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795 }
796
797 /* add the key into the new space */
David Howellsf70e2e02010-04-30 14:32:39 +0100798 nklist->keys[nklist->delkey] = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 }
800
David Howellsceb73c12011-01-25 16:34:28 +0000801 prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
David Howellscab8eb52006-01-08 01:02:45 -0800802done:
David Howellsceb73c12011-01-25 16:34:28 +0000803 *_prealloc = prealloc;
David Howellsf70e2e02010-04-30 14:32:39 +0100804 kleave(" = 0");
805 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806
David Howellsf70e2e02010-04-30 14:32:39 +0100807error_quota:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 /* undo the quota changes */
809 key_payload_reserve(keyring,
810 keyring->datalen - KEYQUOTA_LINK_BYTES);
David Howellsf70e2e02010-04-30 14:32:39 +0100811error_sem:
812 if (type == &key_type_keyring)
813 up_write(&keyring_serialise_link_sem);
814error_krsem:
815 up_write(&keyring->sem);
816 kleave(" = %d", ret);
817 return ret;
818}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819
David Howellsf70e2e02010-04-30 14:32:39 +0100820/*
David Howells973c9f42011-01-20 16:38:33 +0000821 * Check already instantiated keys aren't going to be a problem.
822 *
823 * The caller must have called __key_link_begin(). Don't need to call this for
824 * keys that were created since __key_link_begin() was called.
David Howellsf70e2e02010-04-30 14:32:39 +0100825 */
826int __key_link_check_live_key(struct key *keyring, struct key *key)
827{
828 if (key->type == &key_type_keyring)
829 /* check that we aren't going to create a cycle by linking one
830 * keyring to another */
831 return keyring_detect_cycle(keyring, key);
832 return 0;
833}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700834
David Howellsf70e2e02010-04-30 14:32:39 +0100835/*
David Howells973c9f42011-01-20 16:38:33 +0000836 * Link a key into to a keyring.
837 *
838 * Must be called with __key_link_begin() having being called. Discards any
839 * already extant link to matching key if there is one, so that each keyring
840 * holds at most one link to any given key of a particular type+description
841 * combination.
David Howellsf70e2e02010-04-30 14:32:39 +0100842 */
843void __key_link(struct key *keyring, struct key *key,
David Howellsceb73c12011-01-25 16:34:28 +0000844 unsigned long *_prealloc)
David Howellsf70e2e02010-04-30 14:32:39 +0100845{
846 struct keyring_list *klist, *nklist;
847
David Howellsceb73c12011-01-25 16:34:28 +0000848 nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA);
849 *_prealloc = 0;
David Howellsf70e2e02010-04-30 14:32:39 +0100850
851 kenter("%d,%d,%p", keyring->serial, key->serial, nklist);
852
853 klist = rcu_dereference_protected(keyring->payload.subscriptions,
854 rwsem_is_locked(&keyring->sem));
855
856 atomic_inc(&key->usage);
857
858 /* there's a matching key we can displace or an empty slot in a newly
859 * allocated list we can fill */
860 if (nklist) {
861 kdebug("replace %hu/%hu/%hu",
862 nklist->delkey, nklist->nkeys, nklist->maxkeys);
863
864 nklist->keys[nklist->delkey] = key;
865
866 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
867
868 /* dispose of the old keyring list and, if there was one, the
869 * displaced key */
870 if (klist) {
871 kdebug("dispose %hu/%hu/%hu",
872 klist->delkey, klist->nkeys, klist->maxkeys);
873 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
874 }
875 } else {
876 /* there's sufficient slack space to append directly */
877 klist->keys[klist->nkeys] = key;
878 smp_wmb();
879 klist->nkeys++;
880 }
881}
882
883/*
David Howells973c9f42011-01-20 16:38:33 +0000884 * Finish linking a key into to a keyring.
885 *
886 * Must be called with __key_link_begin() having being called.
David Howellsf70e2e02010-04-30 14:32:39 +0100887 */
888void __key_link_end(struct key *keyring, struct key_type *type,
David Howellsceb73c12011-01-25 16:34:28 +0000889 unsigned long prealloc)
David Howellsf70e2e02010-04-30 14:32:39 +0100890 __releases(&keyring->sem)
891{
892 BUG_ON(type == NULL);
893 BUG_ON(type->name == NULL);
David Howellsceb73c12011-01-25 16:34:28 +0000894 kenter("%d,%s,%lx", keyring->serial, type->name, prealloc);
David Howellsf70e2e02010-04-30 14:32:39 +0100895
896 if (type == &key_type_keyring)
897 up_write(&keyring_serialise_link_sem);
898
899 if (prealloc) {
David Howellsceb73c12011-01-25 16:34:28 +0000900 if (prealloc & KEY_LINK_FIXQUOTA)
901 key_payload_reserve(keyring,
902 keyring->datalen -
903 KEYQUOTA_LINK_BYTES);
904 kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA));
David Howellsf70e2e02010-04-30 14:32:39 +0100905 }
906 up_write(&keyring->sem);
907}
908
David Howells973c9f42011-01-20 16:38:33 +0000909/**
910 * key_link - Link a key to a keyring
911 * @keyring: The keyring to make the link in.
912 * @key: The key to link to.
913 *
914 * Make a link in a keyring to a key, such that the keyring holds a reference
915 * on that key and the key can potentially be found by searching that keyring.
916 *
917 * This function will write-lock the keyring's semaphore and will consume some
918 * of the user's key data quota to hold the link.
919 *
920 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
921 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
922 * full, -EDQUOT if there is insufficient key data quota remaining to add
923 * another link or -ENOMEM if there's insufficient memory.
924 *
925 * It is assumed that the caller has checked that it is permitted for a link to
926 * be made (the keyring should have Write permission and the key Link
927 * permission).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928 */
929int key_link(struct key *keyring, struct key *key)
930{
David Howellsceb73c12011-01-25 16:34:28 +0000931 unsigned long prealloc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932 int ret;
933
934 key_check(keyring);
935 key_check(key);
936
David Howellsf70e2e02010-04-30 14:32:39 +0100937 ret = __key_link_begin(keyring, key->type, key->description, &prealloc);
938 if (ret == 0) {
939 ret = __key_link_check_live_key(keyring, key);
940 if (ret == 0)
941 __key_link(keyring, key, &prealloc);
942 __key_link_end(keyring, key->type, prealloc);
943 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944
945 return ret;
David Howellsf70e2e02010-04-30 14:32:39 +0100946}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947EXPORT_SYMBOL(key_link);
948
David Howells973c9f42011-01-20 16:38:33 +0000949/**
950 * key_unlink - Unlink the first link to a key from a keyring.
951 * @keyring: The keyring to remove the link from.
952 * @key: The key the link is to.
953 *
954 * Remove a link from a keyring to a key.
955 *
956 * This function will write-lock the keyring's semaphore.
957 *
958 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
959 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
960 * memory.
961 *
962 * It is assumed that the caller has checked that it is permitted for a link to
963 * be removed (the keyring should have Write permission; no permissions are
964 * required on the key).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965 */
966int key_unlink(struct key *keyring, struct key *key)
967{
David Howells76d8aea2005-06-23 22:00:49 -0700968 struct keyring_list *klist, *nklist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 int loop, ret;
970
971 key_check(keyring);
972 key_check(key);
973
974 ret = -ENOTDIR;
975 if (keyring->type != &key_type_keyring)
976 goto error;
977
978 down_write(&keyring->sem);
979
David Howellsf0641cb2010-04-30 14:32:18 +0100980 klist = rcu_dereference_locked_keyring(keyring);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981 if (klist) {
982 /* search the keyring for the key */
983 for (loop = 0; loop < klist->nkeys; loop++)
984 if (klist->keys[loop] == key)
985 goto key_is_present;
986 }
987
988 up_write(&keyring->sem);
989 ret = -ENOENT;
990 goto error;
991
David Howells76d8aea2005-06-23 22:00:49 -0700992key_is_present:
993 /* we need to copy the key list for RCU purposes */
David Howellsa4014d82005-07-07 17:57:03 -0700994 nklist = kmalloc(sizeof(*klist) +
995 sizeof(struct key *) * klist->maxkeys,
David Howells76d8aea2005-06-23 22:00:49 -0700996 GFP_KERNEL);
997 if (!nklist)
998 goto nomem;
999 nklist->maxkeys = klist->maxkeys;
1000 nklist->nkeys = klist->nkeys - 1;
1001
1002 if (loop > 0)
1003 memcpy(&nklist->keys[0],
1004 &klist->keys[0],
David Howellsa4014d82005-07-07 17:57:03 -07001005 loop * sizeof(struct key *));
David Howells76d8aea2005-06-23 22:00:49 -07001006
1007 if (loop < nklist->nkeys)
1008 memcpy(&nklist->keys[loop],
1009 &klist->keys[loop + 1],
David Howellsa4014d82005-07-07 17:57:03 -07001010 (nklist->nkeys - loop) * sizeof(struct key *));
David Howells76d8aea2005-06-23 22:00:49 -07001011
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012 /* adjust the user's quota */
1013 key_payload_reserve(keyring,
1014 keyring->datalen - KEYQUOTA_LINK_BYTES);
1015
David Howells76d8aea2005-06-23 22:00:49 -07001016 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017
1018 up_write(&keyring->sem);
David Howells76d8aea2005-06-23 22:00:49 -07001019
1020 /* schedule for later cleanup */
1021 klist->delkey = loop;
1022 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
1023
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024 ret = 0;
1025
David Howells76d8aea2005-06-23 22:00:49 -07001026error:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027 return ret;
David Howells76d8aea2005-06-23 22:00:49 -07001028nomem:
1029 ret = -ENOMEM;
1030 up_write(&keyring->sem);
1031 goto error;
David Howellsa8b17ed2011-01-20 16:38:27 +00001032}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001033EXPORT_SYMBOL(key_unlink);
1034
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035/*
David Howells973c9f42011-01-20 16:38:33 +00001036 * Dispose of a keyring list after the RCU grace period, releasing the keys it
1037 * links to.
David Howells76d8aea2005-06-23 22:00:49 -07001038 */
1039static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
1040{
1041 struct keyring_list *klist;
1042 int loop;
1043
1044 klist = container_of(rcu, struct keyring_list, rcu);
1045
1046 for (loop = klist->nkeys - 1; loop >= 0; loop--)
1047 key_put(klist->keys[loop]);
1048
1049 kfree(klist);
David Howellsa8b17ed2011-01-20 16:38:27 +00001050}
David Howells76d8aea2005-06-23 22:00:49 -07001051
David Howells973c9f42011-01-20 16:38:33 +00001052/**
1053 * keyring_clear - Clear a keyring
1054 * @keyring: The keyring to clear.
1055 *
1056 * Clear the contents of the specified keyring.
1057 *
1058 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059 */
1060int keyring_clear(struct key *keyring)
1061{
1062 struct keyring_list *klist;
David Howells76d8aea2005-06-23 22:00:49 -07001063 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064
1065 ret = -ENOTDIR;
1066 if (keyring->type == &key_type_keyring) {
1067 /* detach the pointer block with the locks held */
1068 down_write(&keyring->sem);
1069
David Howellsf0641cb2010-04-30 14:32:18 +01001070 klist = rcu_dereference_locked_keyring(keyring);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071 if (klist) {
1072 /* adjust the quota */
1073 key_payload_reserve(keyring,
1074 sizeof(struct keyring_list));
1075
David Howells76d8aea2005-06-23 22:00:49 -07001076 rcu_assign_pointer(keyring->payload.subscriptions,
1077 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 }
1079
1080 up_write(&keyring->sem);
1081
1082 /* free the keys after the locks have been dropped */
David Howells76d8aea2005-06-23 22:00:49 -07001083 if (klist)
1084 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085
1086 ret = 0;
1087 }
1088
1089 return ret;
David Howellsa8b17ed2011-01-20 16:38:27 +00001090}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091EXPORT_SYMBOL(keyring_clear);
David Howells31204ed2006-06-26 00:24:51 -07001092
David Howells31204ed2006-06-26 00:24:51 -07001093/*
David Howells973c9f42011-01-20 16:38:33 +00001094 * Dispose of the links from a revoked keyring.
1095 *
1096 * This is called with the key sem write-locked.
David Howells31204ed2006-06-26 00:24:51 -07001097 */
1098static void keyring_revoke(struct key *keyring)
1099{
David Howellsf0641cb2010-04-30 14:32:18 +01001100 struct keyring_list *klist;
1101
1102 klist = rcu_dereference_locked_keyring(keyring);
David Howells31204ed2006-06-26 00:24:51 -07001103
1104 /* adjust the quota */
1105 key_payload_reserve(keyring, 0);
1106
1107 if (klist) {
1108 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1109 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1110 }
David Howellsa8b17ed2011-01-20 16:38:27 +00001111}
David Howells5d135442009-09-02 09:14:00 +01001112
1113/*
David Howells973c9f42011-01-20 16:38:33 +00001114 * Determine whether a key is dead.
David Howells5d135442009-09-02 09:14:00 +01001115 */
1116static bool key_is_dead(struct key *key, time_t limit)
1117{
1118 return test_bit(KEY_FLAG_DEAD, &key->flags) ||
1119 (key->expiry > 0 && key->expiry <= limit);
1120}
1121
1122/*
David Howells973c9f42011-01-20 16:38:33 +00001123 * Collect garbage from the contents of a keyring, replacing the old list with
1124 * a new one with the pointers all shuffled down.
1125 *
1126 * Dead keys are classed as oned that are flagged as being dead or are revoked,
1127 * expired or negative keys that were revoked or expired before the specified
1128 * limit.
David Howells5d135442009-09-02 09:14:00 +01001129 */
1130void keyring_gc(struct key *keyring, time_t limit)
1131{
1132 struct keyring_list *klist, *new;
1133 struct key *key;
1134 int loop, keep, max;
1135
David Howellsc08ef802009-09-14 17:26:13 +01001136 kenter("{%x,%s}", key_serial(keyring), keyring->description);
David Howells5d135442009-09-02 09:14:00 +01001137
1138 down_write(&keyring->sem);
1139
David Howellsf0641cb2010-04-30 14:32:18 +01001140 klist = rcu_dereference_locked_keyring(keyring);
David Howells5d135442009-09-02 09:14:00 +01001141 if (!klist)
David Howellsc08ef802009-09-14 17:26:13 +01001142 goto no_klist;
David Howells5d135442009-09-02 09:14:00 +01001143
1144 /* work out how many subscriptions we're keeping */
1145 keep = 0;
1146 for (loop = klist->nkeys - 1; loop >= 0; loop--)
David Howellsc08ef802009-09-14 17:26:13 +01001147 if (!key_is_dead(klist->keys[loop], limit))
David Howells5d135442009-09-02 09:14:00 +01001148 keep++;
1149
1150 if (keep == klist->nkeys)
1151 goto just_return;
1152
1153 /* allocate a new keyring payload */
1154 max = roundup(keep, 4);
1155 new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *),
1156 GFP_KERNEL);
1157 if (!new)
David Howellsc08ef802009-09-14 17:26:13 +01001158 goto nomem;
David Howells5d135442009-09-02 09:14:00 +01001159 new->maxkeys = max;
1160 new->nkeys = 0;
1161 new->delkey = 0;
1162
1163 /* install the live keys
1164 * - must take care as expired keys may be updated back to life
1165 */
1166 keep = 0;
1167 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
1168 key = klist->keys[loop];
1169 if (!key_is_dead(key, limit)) {
1170 if (keep >= max)
1171 goto discard_new;
1172 new->keys[keep++] = key_get(key);
1173 }
1174 }
1175 new->nkeys = keep;
1176
1177 /* adjust the quota */
1178 key_payload_reserve(keyring,
1179 sizeof(struct keyring_list) +
1180 KEYQUOTA_LINK_BYTES * keep);
1181
1182 if (keep == 0) {
1183 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1184 kfree(new);
1185 } else {
1186 rcu_assign_pointer(keyring->payload.subscriptions, new);
1187 }
1188
1189 up_write(&keyring->sem);
1190
1191 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1192 kleave(" [yes]");
1193 return;
1194
1195discard_new:
1196 new->nkeys = keep;
1197 keyring_clear_rcu_disposal(&new->rcu);
David Howellsc08ef802009-09-14 17:26:13 +01001198 up_write(&keyring->sem);
1199 kleave(" [discard]");
1200 return;
1201
David Howells5d135442009-09-02 09:14:00 +01001202just_return:
1203 up_write(&keyring->sem);
David Howellsc08ef802009-09-14 17:26:13 +01001204 kleave(" [no dead]");
1205 return;
1206
1207no_klist:
1208 up_write(&keyring->sem);
1209 kleave(" [no_klist]");
1210 return;
1211
1212nomem:
1213 up_write(&keyring->sem);
1214 kleave(" [oom]");
David Howells5d135442009-09-02 09:14:00 +01001215}