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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,
Paul E. McKenneye7b0a612010-02-22 17:04:56 -0800158 atomic_read(&keyring->usage) == 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 if (klist) {
160 for (loop = klist->nkeys - 1; loop >= 0; loop--)
161 key_put(klist->keys[loop]);
162 kfree(klist);
163 }
David Howellsa8b17ed2011-01-20 16:38:27 +0000164}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166/*
David Howells973c9f42011-01-20 16:38:33 +0000167 * Describe a keyring for /proc.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 */
169static void keyring_describe(const struct key *keyring, struct seq_file *m)
170{
171 struct keyring_list *klist;
172
wzt.wzt@gmail.comc8563472010-03-04 21:26:23 +0800173 if (keyring->description)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 seq_puts(m, keyring->description);
wzt.wzt@gmail.comc8563472010-03-04 21:26:23 +0800175 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 seq_puts(m, "[anon]");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177
David Howells78b72802011-03-11 17:57:23 +0000178 if (key_is_instantiated(keyring)) {
179 rcu_read_lock();
180 klist = rcu_dereference(keyring->payload.subscriptions);
181 if (klist)
182 seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
183 else
184 seq_puts(m, ": empty");
185 rcu_read_unlock();
186 }
David Howellsa8b17ed2011-01-20 16:38:27 +0000187}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189/*
David Howells973c9f42011-01-20 16:38:33 +0000190 * Read a list of key IDs from the keyring's contents in binary form
191 *
192 * The keyring's semaphore is read-locked by the caller.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 */
194static long keyring_read(const struct key *keyring,
195 char __user *buffer, size_t buflen)
196{
197 struct keyring_list *klist;
198 struct key *key;
199 size_t qty, tmp;
200 int loop, ret;
201
202 ret = 0;
David Howellsf0641cb2010-04-30 14:32:18 +0100203 klist = rcu_dereference_locked_keyring(keyring);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 if (klist) {
205 /* calculate how much data we could return */
206 qty = klist->nkeys * sizeof(key_serial_t);
207
208 if (buffer && buflen > 0) {
209 if (buflen > qty)
210 buflen = qty;
211
212 /* copy the IDs of the subscribed keys into the
213 * buffer */
214 ret = -EFAULT;
215
216 for (loop = 0; loop < klist->nkeys; loop++) {
217 key = klist->keys[loop];
218
219 tmp = sizeof(key_serial_t);
220 if (tmp > buflen)
221 tmp = buflen;
222
223 if (copy_to_user(buffer,
224 &key->serial,
225 tmp) != 0)
226 goto error;
227
228 buflen -= tmp;
229 if (buflen == 0)
230 break;
231 buffer += tmp;
232 }
233 }
234
235 ret = qty;
236 }
237
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700238error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 return ret;
David Howellsa8b17ed2011-01-20 16:38:27 +0000240}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242/*
David Howells973c9f42011-01-20 16:38:33 +0000243 * Allocate a keyring and link into the destination keyring.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 */
245struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
David Howellsd84f4f92008-11-14 10:39:23 +1100246 const struct cred *cred, unsigned long flags,
Michael LeMayd7200242006-06-22 14:47:17 -0700247 struct key *dest)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248{
249 struct key *keyring;
250 int ret;
251
252 keyring = key_alloc(&key_type_keyring, description,
David Howellsd84f4f92008-11-14 10:39:23 +1100253 uid, gid, cred,
David Howells29db9192005-10-30 15:02:44 -0800254 (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
David Howells7e047ef2006-06-26 00:24:50 -0700255 flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256
257 if (!IS_ERR(keyring)) {
David Howells3e301482005-06-23 22:00:56 -0700258 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 if (ret < 0) {
260 key_put(keyring);
261 keyring = ERR_PTR(ret);
262 }
263 }
264
265 return keyring;
David Howellsa8b17ed2011-01-20 16:38:27 +0000266}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267
David Howells973c9f42011-01-20 16:38:33 +0000268/**
269 * keyring_search_aux - Search a keyring tree for a key matching some criteria
270 * @keyring_ref: A pointer to the keyring with possession indicator.
271 * @cred: The credentials to use for permissions checks.
272 * @type: The type of key to search for.
273 * @description: Parameter for @match.
274 * @match: Function to rule on whether or not a key is the one required.
David Howells78b72802011-03-11 17:57:23 +0000275 * @no_state_check: Don't check if a matching key is bad
David Howells973c9f42011-01-20 16:38:33 +0000276 *
277 * Search the supplied keyring tree for a key that matches the criteria given.
278 * The root keyring and any linked keyrings must grant Search permission to the
279 * caller to be searchable and keys can only be found if they too grant Search
280 * to the caller. The possession flag on the root keyring pointer controls use
281 * of the possessor bits in permissions checking of the entire tree. In
282 * addition, the LSM gets to forbid keyring searches and key matches.
283 *
284 * The search is performed as a breadth-then-depth search up to the prescribed
285 * limit (KEYRING_SEARCH_MAX_DEPTH).
286 *
287 * Keys are matched to the type provided and are then filtered by the match
288 * function, which is given the description to use in any way it sees fit. The
289 * match function may use any attributes of a key that it wishes to to
290 * determine the match. Normally the match function from the key type would be
291 * used.
292 *
293 * RCU is used to prevent the keyring key lists from disappearing without the
294 * need to take lots of locks.
295 *
296 * Returns a pointer to the found key and increments the key usage count if
297 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
298 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
299 * specified keyring wasn't a keyring.
300 *
301 * In the case of a successful return, the possession attribute from
302 * @keyring_ref is propagated to the returned key reference.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 */
David Howells664cceb2005-09-28 17:03:15 +0100304key_ref_t keyring_search_aux(key_ref_t keyring_ref,
David Howellsd84f4f92008-11-14 10:39:23 +1100305 const struct cred *cred,
David Howells664cceb2005-09-28 17:03:15 +0100306 struct key_type *type,
307 const void *description,
David Howells78b72802011-03-11 17:57:23 +0000308 key_match_func_t match,
309 bool no_state_check)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310{
311 struct {
David Howells76d8aea2005-06-23 22:00:49 -0700312 struct keyring_list *keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 int kix;
314 } stack[KEYRING_SEARCH_MAX_DEPTH];
315
316 struct keyring_list *keylist;
317 struct timespec now;
Kevin Coffmandceba992008-04-29 01:01:22 -0700318 unsigned long possessed, kflags;
David Howells664cceb2005-09-28 17:03:15 +0100319 struct key *keyring, *key;
320 key_ref_t key_ref;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321 long err;
David Howells76d8aea2005-06-23 22:00:49 -0700322 int sp, kix;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323
David Howells664cceb2005-09-28 17:03:15 +0100324 keyring = key_ref_to_ptr(keyring_ref);
325 possessed = is_key_possessed(keyring_ref);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 key_check(keyring);
327
328 /* top keyring must have search permission to begin the search */
Chihau Chau512ea3b2010-03-08 20:11:34 -0300329 err = key_task_permission(keyring_ref, cred, KEY_SEARCH);
David Howells29db9192005-10-30 15:02:44 -0800330 if (err < 0) {
331 key_ref = ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 goto error;
David Howells29db9192005-10-30 15:02:44 -0800333 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334
David Howells664cceb2005-09-28 17:03:15 +0100335 key_ref = ERR_PTR(-ENOTDIR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 if (keyring->type != &key_type_keyring)
337 goto error;
338
David Howells664cceb2005-09-28 17:03:15 +0100339 rcu_read_lock();
340
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 now = current_kernel_time();
342 err = -EAGAIN;
343 sp = 0;
344
Kevin Coffmandceba992008-04-29 01:01:22 -0700345 /* firstly we should check to see if this top-level keyring is what we
346 * are looking for */
347 key_ref = ERR_PTR(-EAGAIN);
348 kflags = keyring->flags;
349 if (keyring->type == type && match(keyring, description)) {
350 key = keyring;
David Howells78b72802011-03-11 17:57:23 +0000351 if (no_state_check)
352 goto found;
Kevin Coffmandceba992008-04-29 01:01:22 -0700353
354 /* check it isn't negative and hasn't expired or been
355 * revoked */
356 if (kflags & (1 << KEY_FLAG_REVOKED))
357 goto error_2;
358 if (key->expiry && now.tv_sec >= key->expiry)
359 goto error_2;
David Howellsfdd1b942011-03-07 15:06:09 +0000360 key_ref = ERR_PTR(key->type_data.reject_error);
Kevin Coffmandceba992008-04-29 01:01:22 -0700361 if (kflags & (1 << KEY_FLAG_NEGATIVE))
362 goto error_2;
363 goto found;
364 }
365
366 /* otherwise, the top keyring must not be revoked, expired, or
367 * negatively instantiated if we are to search it */
368 key_ref = ERR_PTR(-EAGAIN);
369 if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) ||
370 (keyring->expiry && now.tv_sec >= keyring->expiry))
371 goto error_2;
372
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 /* start processing a new keyring */
David Howells664cceb2005-09-28 17:03:15 +0100374descend:
David Howells76d8aea2005-06-23 22:00:49 -0700375 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 goto not_this_keyring;
377
David Howells76d8aea2005-06-23 22:00:49 -0700378 keylist = rcu_dereference(keyring->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 if (!keylist)
380 goto not_this_keyring;
381
382 /* iterate through the keys in this keyring first */
383 for (kix = 0; kix < keylist->nkeys; kix++) {
384 key = keylist->keys[kix];
Kevin Coffmandceba992008-04-29 01:01:22 -0700385 kflags = key->flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386
387 /* ignore keys not of this type */
388 if (key->type != type)
389 continue;
390
391 /* skip revoked keys and expired keys */
David Howells78b72802011-03-11 17:57:23 +0000392 if (!no_state_check) {
393 if (kflags & (1 << KEY_FLAG_REVOKED))
394 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395
David Howells78b72802011-03-11 17:57:23 +0000396 if (key->expiry && now.tv_sec >= key->expiry)
397 continue;
398 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399
400 /* keys that don't match */
401 if (!match(key, description))
402 continue;
403
404 /* key must have search permissions */
David Howells29db9192005-10-30 15:02:44 -0800405 if (key_task_permission(make_key_ref(key, possessed),
David Howellsd84f4f92008-11-14 10:39:23 +1100406 cred, KEY_SEARCH) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 continue;
408
David Howells78b72802011-03-11 17:57:23 +0000409 if (no_state_check)
410 goto found;
411
Kevin Coffmandceba992008-04-29 01:01:22 -0700412 /* we set a different error code if we pass a negative key */
413 if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
David Howellsfdd1b942011-03-07 15:06:09 +0000414 err = key->type_data.reject_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 continue;
416 }
417
418 goto found;
419 }
420
421 /* search through the keyrings nested in this one */
422 kix = 0;
David Howells664cceb2005-09-28 17:03:15 +0100423ascend:
David Howells76d8aea2005-06-23 22:00:49 -0700424 for (; kix < keylist->nkeys; kix++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425 key = keylist->keys[kix];
426 if (key->type != &key_type_keyring)
David Howells76d8aea2005-06-23 22:00:49 -0700427 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428
429 /* recursively search nested keyrings
430 * - only search keyrings for which we have search permission
431 */
432 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
David Howells76d8aea2005-06-23 22:00:49 -0700433 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434
David Howells0f6ed7c2005-11-07 00:59:30 -0800435 if (key_task_permission(make_key_ref(key, possessed),
David Howellsd84f4f92008-11-14 10:39:23 +1100436 cred, KEY_SEARCH) < 0)
David Howells76d8aea2005-06-23 22:00:49 -0700437 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438
439 /* stack the current position */
David Howells76d8aea2005-06-23 22:00:49 -0700440 stack[sp].keylist = keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 stack[sp].kix = kix;
442 sp++;
443
444 /* begin again with the new keyring */
445 keyring = key;
446 goto descend;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 }
448
449 /* the keyring we're looking at was disqualified or didn't contain a
450 * matching key */
David Howells664cceb2005-09-28 17:03:15 +0100451not_this_keyring:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 if (sp > 0) {
453 /* resume the processing of a keyring higher up in the tree */
454 sp--;
David Howells76d8aea2005-06-23 22:00:49 -0700455 keylist = stack[sp].keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 kix = stack[sp].kix + 1;
457 goto ascend;
458 }
459
David Howells664cceb2005-09-28 17:03:15 +0100460 key_ref = ERR_PTR(err);
461 goto error_2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462
463 /* we found a viable match */
David Howells664cceb2005-09-28 17:03:15 +0100464found:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 atomic_inc(&key->usage);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 key_check(key);
David Howells664cceb2005-09-28 17:03:15 +0100467 key_ref = make_key_ref(key, possessed);
468error_2:
David Howells76d8aea2005-06-23 22:00:49 -0700469 rcu_read_unlock();
David Howells664cceb2005-09-28 17:03:15 +0100470error:
471 return key_ref;
David Howellsa8b17ed2011-01-20 16:38:27 +0000472}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473
David Howells973c9f42011-01-20 16:38:33 +0000474/**
475 * keyring_search - Search the supplied keyring tree for a matching key
476 * @keyring: The root of the keyring tree to be searched.
477 * @type: The type of keyring we want to find.
478 * @description: The name of the keyring we want to find.
479 *
480 * As keyring_search_aux() above, but using the current task's credentials and
481 * type's default matching function.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482 */
David Howells664cceb2005-09-28 17:03:15 +0100483key_ref_t keyring_search(key_ref_t keyring,
484 struct key_type *type,
485 const char *description)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486{
David Howells3e301482005-06-23 22:00:56 -0700487 if (!type->match)
488 return ERR_PTR(-ENOKEY);
489
David Howellsd84f4f92008-11-14 10:39:23 +1100490 return keyring_search_aux(keyring, current->cred,
David Howells78b72802011-03-11 17:57:23 +0000491 type, description, type->match, false);
David Howellsa8b17ed2011-01-20 16:38:27 +0000492}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493EXPORT_SYMBOL(keyring_search);
494
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495/*
David Howells973c9f42011-01-20 16:38:33 +0000496 * Search the given keyring only (no recursion).
497 *
498 * The caller must guarantee that the keyring is a keyring and that the
499 * permission is granted to search the keyring as no check is made here.
500 *
501 * RCU is used to make it unnecessary to lock the keyring key list here.
502 *
503 * Returns a pointer to the found key with usage count incremented if
504 * successful and returns -ENOKEY if not found. Revoked keys and keys not
505 * providing the requested permission are skipped over.
506 *
507 * If successful, the possession indicator is propagated from the keyring ref
508 * to the returned key reference.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 */
David Howells664cceb2005-09-28 17:03:15 +0100510key_ref_t __keyring_search_one(key_ref_t keyring_ref,
511 const struct key_type *ktype,
512 const char *description,
513 key_perm_t perm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514{
515 struct keyring_list *klist;
David Howells664cceb2005-09-28 17:03:15 +0100516 unsigned long possessed;
517 struct key *keyring, *key;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 int loop;
519
David Howells664cceb2005-09-28 17:03:15 +0100520 keyring = key_ref_to_ptr(keyring_ref);
521 possessed = is_key_possessed(keyring_ref);
522
David Howells76d8aea2005-06-23 22:00:49 -0700523 rcu_read_lock();
524
525 klist = rcu_dereference(keyring->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 if (klist) {
527 for (loop = 0; loop < klist->nkeys; loop++) {
528 key = klist->keys[loop];
529
530 if (key->type == ktype &&
David Howells3e301482005-06-23 22:00:56 -0700531 (!key->type->match ||
532 key->type->match(key, description)) &&
David Howells664cceb2005-09-28 17:03:15 +0100533 key_permission(make_key_ref(key, possessed),
David Howellsdb1d1d52005-12-01 00:51:18 -0800534 perm) == 0 &&
David Howells76d8aea2005-06-23 22:00:49 -0700535 !test_bit(KEY_FLAG_REVOKED, &key->flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 )
537 goto found;
538 }
539 }
540
David Howells664cceb2005-09-28 17:03:15 +0100541 rcu_read_unlock();
542 return ERR_PTR(-ENOKEY);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700544found:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 atomic_inc(&key->usage);
David Howells76d8aea2005-06-23 22:00:49 -0700546 rcu_read_unlock();
David Howells664cceb2005-09-28 17:03:15 +0100547 return make_key_ref(key, possessed);
David Howellsa8b17ed2011-01-20 16:38:27 +0000548}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550/*
David Howells973c9f42011-01-20 16:38:33 +0000551 * Find a keyring with the specified name.
552 *
553 * All named keyrings in the current user namespace are searched, provided they
554 * grant Search permission directly to the caller (unless this check is
555 * skipped). Keyrings whose usage points have reached zero or who have been
556 * revoked are skipped.
557 *
558 * Returns a pointer to the keyring with the keyring's refcount having being
559 * incremented on success. -ENOKEY is returned if a key could not be found.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 */
David Howells69664cf2008-04-29 01:01:31 -0700561struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562{
563 struct key *keyring;
564 int bucket;
565
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 if (!name)
Toshiyuki Okajimacea7daa2010-04-30 14:32:13 +0100567 return ERR_PTR(-EINVAL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568
569 bucket = keyring_hash(name);
570
571 read_lock(&keyring_name_lock);
572
573 if (keyring_name_hash[bucket].next) {
574 /* search this hash bucket for a keyring with a matching name
575 * that's readable and that hasn't been revoked */
576 list_for_each_entry(keyring,
577 &keyring_name_hash[bucket],
578 type_data.link
579 ) {
Serge E. Hallyn2ea190d2009-02-26 18:27:55 -0600580 if (keyring->user->user_ns != current_user_ns())
581 continue;
582
David Howells76d8aea2005-06-23 22:00:49 -0700583 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 continue;
585
586 if (strcmp(keyring->description, name) != 0)
587 continue;
588
David Howells69664cf2008-04-29 01:01:31 -0700589 if (!skip_perm_check &&
590 key_permission(make_key_ref(keyring, 0),
David Howells0f6ed7c2005-11-07 00:59:30 -0800591 KEY_SEARCH) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 continue;
593
Toshiyuki Okajimacea7daa2010-04-30 14:32:13 +0100594 /* we've got a match but we might end up racing with
595 * key_cleanup() if the keyring is currently 'dead'
596 * (ie. it has a zero usage count) */
597 if (!atomic_inc_not_zero(&keyring->usage))
598 continue;
599 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 }
601 }
602
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 keyring = ERR_PTR(-ENOKEY);
Toshiyuki Okajimacea7daa2010-04-30 14:32:13 +0100604out:
605 read_unlock(&keyring_name_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 return keyring;
David Howellsa8b17ed2011-01-20 16:38:27 +0000607}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609/*
David Howells973c9f42011-01-20 16:38:33 +0000610 * See if a cycle will will be created by inserting acyclic tree B in acyclic
611 * tree A at the topmost level (ie: as a direct child of A).
612 *
613 * Since we are adding B to A at the top level, checking for cycles should just
614 * be a matter of seeing if node A is somewhere in tree B.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 */
616static int keyring_detect_cycle(struct key *A, struct key *B)
617{
618 struct {
David Howells76d8aea2005-06-23 22:00:49 -0700619 struct keyring_list *keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 int kix;
621 } stack[KEYRING_SEARCH_MAX_DEPTH];
622
623 struct keyring_list *keylist;
624 struct key *subtree, *key;
625 int sp, kix, ret;
626
David Howells76d8aea2005-06-23 22:00:49 -0700627 rcu_read_lock();
628
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 ret = -EDEADLK;
630 if (A == B)
David Howells76d8aea2005-06-23 22:00:49 -0700631 goto cycle_detected;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632
633 subtree = B;
634 sp = 0;
635
636 /* start processing a new keyring */
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700637descend:
David Howells76d8aea2005-06-23 22:00:49 -0700638 if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 goto not_this_keyring;
640
David Howells76d8aea2005-06-23 22:00:49 -0700641 keylist = rcu_dereference(subtree->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642 if (!keylist)
643 goto not_this_keyring;
644 kix = 0;
645
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700646ascend:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 /* iterate through the remaining keys in this keyring */
648 for (; kix < keylist->nkeys; kix++) {
649 key = keylist->keys[kix];
650
651 if (key == A)
652 goto cycle_detected;
653
654 /* recursively check nested keyrings */
655 if (key->type == &key_type_keyring) {
656 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
657 goto too_deep;
658
659 /* stack the current position */
David Howells76d8aea2005-06-23 22:00:49 -0700660 stack[sp].keylist = keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 stack[sp].kix = kix;
662 sp++;
663
664 /* begin again with the new keyring */
665 subtree = key;
666 goto descend;
667 }
668 }
669
670 /* the keyring we're looking at was disqualified or didn't contain a
671 * matching key */
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700672not_this_keyring:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 if (sp > 0) {
674 /* resume the checking of a keyring higher up in the tree */
675 sp--;
David Howells76d8aea2005-06-23 22:00:49 -0700676 keylist = stack[sp].keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 kix = stack[sp].kix + 1;
678 goto ascend;
679 }
680
681 ret = 0; /* no cycles detected */
682
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700683error:
David Howells76d8aea2005-06-23 22:00:49 -0700684 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 return ret;
686
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700687too_deep:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 ret = -ELOOP;
David Howells76d8aea2005-06-23 22:00:49 -0700689 goto error;
690
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700691cycle_detected:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 ret = -EDEADLK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 goto error;
David Howellsa8b17ed2011-01-20 16:38:27 +0000694}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695
David Howells76d8aea2005-06-23 22:00:49 -0700696/*
David Howells973c9f42011-01-20 16:38:33 +0000697 * Dispose of a keyring list after the RCU grace period, freeing the unlinked
David Howellscab8eb52006-01-08 01:02:45 -0800698 * key
699 */
700static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
701{
702 struct keyring_list *klist =
703 container_of(rcu, struct keyring_list, rcu);
704
Alexey Dobriyan4be929b2010-05-24 14:33:03 -0700705 if (klist->delkey != USHRT_MAX)
David Howellsf70e2e02010-04-30 14:32:39 +0100706 key_put(klist->keys[klist->delkey]);
David Howellscab8eb52006-01-08 01:02:45 -0800707 kfree(klist);
David Howellsf70e2e02010-04-30 14:32:39 +0100708}
David Howellscab8eb52006-01-08 01:02:45 -0800709
David Howellscab8eb52006-01-08 01:02:45 -0800710/*
David Howells973c9f42011-01-20 16:38:33 +0000711 * Preallocate memory so that a key can be linked into to a keyring.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712 */
David Howellsf70e2e02010-04-30 14:32:39 +0100713int __key_link_begin(struct key *keyring, const struct key_type *type,
David Howellsceb73c12011-01-25 16:34:28 +0000714 const char *description, unsigned long *_prealloc)
David Howellsf70e2e02010-04-30 14:32:39 +0100715 __acquires(&keyring->sem)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716{
717 struct keyring_list *klist, *nklist;
David Howellsceb73c12011-01-25 16:34:28 +0000718 unsigned long prealloc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 unsigned max;
720 size_t size;
David Howellscab8eb52006-01-08 01:02:45 -0800721 int loop, ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722
David Howellsf70e2e02010-04-30 14:32:39 +0100723 kenter("%d,%s,%s,", key_serial(keyring), type->name, description);
724
725 if (keyring->type != &key_type_keyring)
726 return -ENOTDIR;
727
728 down_write(&keyring->sem);
729
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 ret = -EKEYREVOKED;
David Howells76d8aea2005-06-23 22:00:49 -0700731 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
David Howellsf70e2e02010-04-30 14:32:39 +0100732 goto error_krsem;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733
David Howellsf70e2e02010-04-30 14:32:39 +0100734 /* serialise link/link calls to prevent parallel calls causing a cycle
735 * when linking two keyring in opposite orders */
736 if (type == &key_type_keyring)
David Howells553d6032010-04-30 14:32:28 +0100737 down_write(&keyring_serialise_link_sem);
738
David Howellsf70e2e02010-04-30 14:32:39 +0100739 klist = rcu_dereference_locked_keyring(keyring);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740
David Howellscab8eb52006-01-08 01:02:45 -0800741 /* see if there's a matching key we can displace */
David Howellscab8eb52006-01-08 01:02:45 -0800742 if (klist && klist->nkeys > 0) {
David Howellscab8eb52006-01-08 01:02:45 -0800743 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
744 if (klist->keys[loop]->type == type &&
745 strcmp(klist->keys[loop]->description,
David Howellsf70e2e02010-04-30 14:32:39 +0100746 description) == 0
David Howellscab8eb52006-01-08 01:02:45 -0800747 ) {
David Howellsf70e2e02010-04-30 14:32:39 +0100748 /* found a match - we'll replace this one with
749 * the new key */
David Howellscab8eb52006-01-08 01:02:45 -0800750 size = sizeof(struct key *) * klist->maxkeys;
751 size += sizeof(*klist);
752 BUG_ON(size > PAGE_SIZE);
753
754 ret = -ENOMEM;
Eric Sesterhenn48ad5042006-12-06 20:33:47 -0800755 nklist = kmemdup(klist, size, GFP_KERNEL);
David Howellscab8eb52006-01-08 01:02:45 -0800756 if (!nklist)
David Howellsf70e2e02010-04-30 14:32:39 +0100757 goto error_sem;
David Howellscab8eb52006-01-08 01:02:45 -0800758
David Howellsf70e2e02010-04-30 14:32:39 +0100759 /* note replacement slot */
760 klist->delkey = nklist->delkey = loop;
David Howellsceb73c12011-01-25 16:34:28 +0000761 prealloc = (unsigned long)nklist;
David Howellscab8eb52006-01-08 01:02:45 -0800762 goto done;
763 }
764 }
765 }
766
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 /* check that we aren't going to overrun the user's quota */
768 ret = key_payload_reserve(keyring,
769 keyring->datalen + KEYQUOTA_LINK_BYTES);
770 if (ret < 0)
David Howellsf70e2e02010-04-30 14:32:39 +0100771 goto error_sem;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700772
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 if (klist && klist->nkeys < klist->maxkeys) {
David Howellsf70e2e02010-04-30 14:32:39 +0100774 /* there's sufficient slack space to append directly */
775 nklist = NULL;
David Howellsceb73c12011-01-25 16:34:28 +0000776 prealloc = KEY_LINK_FIXQUOTA;
Chihau Chau512ea3b2010-03-08 20:11:34 -0300777 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 /* grow the key list */
779 max = 4;
780 if (klist)
781 max += klist->maxkeys;
782
783 ret = -ENFILE;
Alexey Dobriyan4be929b2010-05-24 14:33:03 -0700784 if (max > USHRT_MAX - 1)
David Howellsf70e2e02010-04-30 14:32:39 +0100785 goto error_quota;
David Howellsa4014d82005-07-07 17:57:03 -0700786 size = sizeof(*klist) + sizeof(struct key *) * max;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787 if (size > PAGE_SIZE)
David Howellsf70e2e02010-04-30 14:32:39 +0100788 goto error_quota;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789
790 ret = -ENOMEM;
791 nklist = kmalloc(size, GFP_KERNEL);
792 if (!nklist)
David Howellsf70e2e02010-04-30 14:32:39 +0100793 goto error_quota;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794
David Howellsf70e2e02010-04-30 14:32:39 +0100795 nklist->maxkeys = max;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 if (klist) {
David Howellsf70e2e02010-04-30 14:32:39 +0100797 memcpy(nklist->keys, klist->keys,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 sizeof(struct key *) * klist->nkeys);
David Howellsf70e2e02010-04-30 14:32:39 +0100799 nklist->delkey = klist->nkeys;
800 nklist->nkeys = klist->nkeys + 1;
Alexey Dobriyan4be929b2010-05-24 14:33:03 -0700801 klist->delkey = USHRT_MAX;
David Howellsf70e2e02010-04-30 14:32:39 +0100802 } else {
803 nklist->nkeys = 1;
804 nklist->delkey = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805 }
806
807 /* add the key into the new space */
David Howellsf70e2e02010-04-30 14:32:39 +0100808 nklist->keys[nklist->delkey] = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809 }
810
David Howellsceb73c12011-01-25 16:34:28 +0000811 prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
David Howellscab8eb52006-01-08 01:02:45 -0800812done:
David Howellsceb73c12011-01-25 16:34:28 +0000813 *_prealloc = prealloc;
David Howellsf70e2e02010-04-30 14:32:39 +0100814 kleave(" = 0");
815 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816
David Howellsf70e2e02010-04-30 14:32:39 +0100817error_quota:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 /* undo the quota changes */
819 key_payload_reserve(keyring,
820 keyring->datalen - KEYQUOTA_LINK_BYTES);
David Howellsf70e2e02010-04-30 14:32:39 +0100821error_sem:
822 if (type == &key_type_keyring)
823 up_write(&keyring_serialise_link_sem);
824error_krsem:
825 up_write(&keyring->sem);
826 kleave(" = %d", ret);
827 return ret;
828}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829
David Howellsf70e2e02010-04-30 14:32:39 +0100830/*
David Howells973c9f42011-01-20 16:38:33 +0000831 * Check already instantiated keys aren't going to be a problem.
832 *
833 * The caller must have called __key_link_begin(). Don't need to call this for
834 * keys that were created since __key_link_begin() was called.
David Howellsf70e2e02010-04-30 14:32:39 +0100835 */
836int __key_link_check_live_key(struct key *keyring, struct key *key)
837{
838 if (key->type == &key_type_keyring)
839 /* check that we aren't going to create a cycle by linking one
840 * keyring to another */
841 return keyring_detect_cycle(keyring, key);
842 return 0;
843}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844
David Howellsf70e2e02010-04-30 14:32:39 +0100845/*
David Howells973c9f42011-01-20 16:38:33 +0000846 * Link a key into to a keyring.
847 *
848 * Must be called with __key_link_begin() having being called. Discards any
849 * already extant link to matching key if there is one, so that each keyring
850 * holds at most one link to any given key of a particular type+description
851 * combination.
David Howellsf70e2e02010-04-30 14:32:39 +0100852 */
853void __key_link(struct key *keyring, struct key *key,
David Howellsceb73c12011-01-25 16:34:28 +0000854 unsigned long *_prealloc)
David Howellsf70e2e02010-04-30 14:32:39 +0100855{
856 struct keyring_list *klist, *nklist;
857
David Howellsceb73c12011-01-25 16:34:28 +0000858 nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA);
859 *_prealloc = 0;
David Howellsf70e2e02010-04-30 14:32:39 +0100860
861 kenter("%d,%d,%p", keyring->serial, key->serial, nklist);
862
863 klist = rcu_dereference_protected(keyring->payload.subscriptions,
864 rwsem_is_locked(&keyring->sem));
865
866 atomic_inc(&key->usage);
867
868 /* there's a matching key we can displace or an empty slot in a newly
869 * allocated list we can fill */
870 if (nklist) {
871 kdebug("replace %hu/%hu/%hu",
872 nklist->delkey, nklist->nkeys, nklist->maxkeys);
873
874 nklist->keys[nklist->delkey] = key;
875
876 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
877
878 /* dispose of the old keyring list and, if there was one, the
879 * displaced key */
880 if (klist) {
881 kdebug("dispose %hu/%hu/%hu",
882 klist->delkey, klist->nkeys, klist->maxkeys);
883 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
884 }
885 } else {
886 /* there's sufficient slack space to append directly */
887 klist->keys[klist->nkeys] = key;
888 smp_wmb();
889 klist->nkeys++;
890 }
891}
892
893/*
David Howells973c9f42011-01-20 16:38:33 +0000894 * Finish linking a key into to a keyring.
895 *
896 * Must be called with __key_link_begin() having being called.
David Howellsf70e2e02010-04-30 14:32:39 +0100897 */
898void __key_link_end(struct key *keyring, struct key_type *type,
David Howellsceb73c12011-01-25 16:34:28 +0000899 unsigned long prealloc)
David Howellsf70e2e02010-04-30 14:32:39 +0100900 __releases(&keyring->sem)
901{
902 BUG_ON(type == NULL);
903 BUG_ON(type->name == NULL);
David Howellsceb73c12011-01-25 16:34:28 +0000904 kenter("%d,%s,%lx", keyring->serial, type->name, prealloc);
David Howellsf70e2e02010-04-30 14:32:39 +0100905
906 if (type == &key_type_keyring)
907 up_write(&keyring_serialise_link_sem);
908
909 if (prealloc) {
David Howellsceb73c12011-01-25 16:34:28 +0000910 if (prealloc & KEY_LINK_FIXQUOTA)
911 key_payload_reserve(keyring,
912 keyring->datalen -
913 KEYQUOTA_LINK_BYTES);
914 kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA));
David Howellsf70e2e02010-04-30 14:32:39 +0100915 }
916 up_write(&keyring->sem);
917}
918
David Howells973c9f42011-01-20 16:38:33 +0000919/**
920 * key_link - Link a key to a keyring
921 * @keyring: The keyring to make the link in.
922 * @key: The key to link to.
923 *
924 * Make a link in a keyring to a key, such that the keyring holds a reference
925 * on that key and the key can potentially be found by searching that keyring.
926 *
927 * This function will write-lock the keyring's semaphore and will consume some
928 * of the user's key data quota to hold the link.
929 *
930 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
931 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
932 * full, -EDQUOT if there is insufficient key data quota remaining to add
933 * another link or -ENOMEM if there's insufficient memory.
934 *
935 * It is assumed that the caller has checked that it is permitted for a link to
936 * be made (the keyring should have Write permission and the key Link
937 * permission).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938 */
939int key_link(struct key *keyring, struct key *key)
940{
David Howellsceb73c12011-01-25 16:34:28 +0000941 unsigned long prealloc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 int ret;
943
944 key_check(keyring);
945 key_check(key);
946
David Howellsf70e2e02010-04-30 14:32:39 +0100947 ret = __key_link_begin(keyring, key->type, key->description, &prealloc);
948 if (ret == 0) {
949 ret = __key_link_check_live_key(keyring, key);
950 if (ret == 0)
951 __key_link(keyring, key, &prealloc);
952 __key_link_end(keyring, key->type, prealloc);
953 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954
955 return ret;
David Howellsf70e2e02010-04-30 14:32:39 +0100956}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700957EXPORT_SYMBOL(key_link);
958
David Howells973c9f42011-01-20 16:38:33 +0000959/**
960 * key_unlink - Unlink the first link to a key from a keyring.
961 * @keyring: The keyring to remove the link from.
962 * @key: The key the link is to.
963 *
964 * Remove a link from a keyring to a key.
965 *
966 * This function will write-lock the keyring's semaphore.
967 *
968 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
969 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
970 * memory.
971 *
972 * It is assumed that the caller has checked that it is permitted for a link to
973 * be removed (the keyring should have Write permission; no permissions are
974 * required on the key).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 */
976int key_unlink(struct key *keyring, struct key *key)
977{
David Howells76d8aea2005-06-23 22:00:49 -0700978 struct keyring_list *klist, *nklist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979 int loop, ret;
980
981 key_check(keyring);
982 key_check(key);
983
984 ret = -ENOTDIR;
985 if (keyring->type != &key_type_keyring)
986 goto error;
987
988 down_write(&keyring->sem);
989
David Howellsf0641cb2010-04-30 14:32:18 +0100990 klist = rcu_dereference_locked_keyring(keyring);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 if (klist) {
992 /* search the keyring for the key */
993 for (loop = 0; loop < klist->nkeys; loop++)
994 if (klist->keys[loop] == key)
995 goto key_is_present;
996 }
997
998 up_write(&keyring->sem);
999 ret = -ENOENT;
1000 goto error;
1001
David Howells76d8aea2005-06-23 22:00:49 -07001002key_is_present:
1003 /* we need to copy the key list for RCU purposes */
David Howellsa4014d82005-07-07 17:57:03 -07001004 nklist = kmalloc(sizeof(*klist) +
1005 sizeof(struct key *) * klist->maxkeys,
David Howells76d8aea2005-06-23 22:00:49 -07001006 GFP_KERNEL);
1007 if (!nklist)
1008 goto nomem;
1009 nklist->maxkeys = klist->maxkeys;
1010 nklist->nkeys = klist->nkeys - 1;
1011
1012 if (loop > 0)
1013 memcpy(&nklist->keys[0],
1014 &klist->keys[0],
David Howellsa4014d82005-07-07 17:57:03 -07001015 loop * sizeof(struct key *));
David Howells76d8aea2005-06-23 22:00:49 -07001016
1017 if (loop < nklist->nkeys)
1018 memcpy(&nklist->keys[loop],
1019 &klist->keys[loop + 1],
David Howellsa4014d82005-07-07 17:57:03 -07001020 (nklist->nkeys - loop) * sizeof(struct key *));
David Howells76d8aea2005-06-23 22:00:49 -07001021
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 /* adjust the user's quota */
1023 key_payload_reserve(keyring,
1024 keyring->datalen - KEYQUOTA_LINK_BYTES);
1025
David Howells76d8aea2005-06-23 22:00:49 -07001026 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027
1028 up_write(&keyring->sem);
David Howells76d8aea2005-06-23 22:00:49 -07001029
1030 /* schedule for later cleanup */
1031 klist->delkey = loop;
1032 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
1033
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034 ret = 0;
1035
David Howells76d8aea2005-06-23 22:00:49 -07001036error:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037 return ret;
David Howells76d8aea2005-06-23 22:00:49 -07001038nomem:
1039 ret = -ENOMEM;
1040 up_write(&keyring->sem);
1041 goto error;
David Howellsa8b17ed2011-01-20 16:38:27 +00001042}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043EXPORT_SYMBOL(key_unlink);
1044
Linus Torvalds1da177e2005-04-16 15:20:36 -07001045/*
David Howells973c9f42011-01-20 16:38:33 +00001046 * Dispose of a keyring list after the RCU grace period, releasing the keys it
1047 * links to.
David Howells76d8aea2005-06-23 22:00:49 -07001048 */
1049static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
1050{
1051 struct keyring_list *klist;
1052 int loop;
1053
1054 klist = container_of(rcu, struct keyring_list, rcu);
1055
1056 for (loop = klist->nkeys - 1; loop >= 0; loop--)
1057 key_put(klist->keys[loop]);
1058
1059 kfree(klist);
David Howellsa8b17ed2011-01-20 16:38:27 +00001060}
David Howells76d8aea2005-06-23 22:00:49 -07001061
David Howells973c9f42011-01-20 16:38:33 +00001062/**
1063 * keyring_clear - Clear a keyring
1064 * @keyring: The keyring to clear.
1065 *
1066 * Clear the contents of the specified keyring.
1067 *
1068 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 */
1070int keyring_clear(struct key *keyring)
1071{
1072 struct keyring_list *klist;
David Howells76d8aea2005-06-23 22:00:49 -07001073 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001074
1075 ret = -ENOTDIR;
1076 if (keyring->type == &key_type_keyring) {
1077 /* detach the pointer block with the locks held */
1078 down_write(&keyring->sem);
1079
David Howellsf0641cb2010-04-30 14:32:18 +01001080 klist = rcu_dereference_locked_keyring(keyring);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001081 if (klist) {
1082 /* adjust the quota */
1083 key_payload_reserve(keyring,
1084 sizeof(struct keyring_list));
1085
David Howells76d8aea2005-06-23 22:00:49 -07001086 rcu_assign_pointer(keyring->payload.subscriptions,
1087 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088 }
1089
1090 up_write(&keyring->sem);
1091
1092 /* free the keys after the locks have been dropped */
David Howells76d8aea2005-06-23 22:00:49 -07001093 if (klist)
1094 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095
1096 ret = 0;
1097 }
1098
1099 return ret;
David Howellsa8b17ed2011-01-20 16:38:27 +00001100}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101EXPORT_SYMBOL(keyring_clear);
David Howells31204ed2006-06-26 00:24:51 -07001102
David Howells31204ed2006-06-26 00:24:51 -07001103/*
David Howells973c9f42011-01-20 16:38:33 +00001104 * Dispose of the links from a revoked keyring.
1105 *
1106 * This is called with the key sem write-locked.
David Howells31204ed2006-06-26 00:24:51 -07001107 */
1108static void keyring_revoke(struct key *keyring)
1109{
David Howellsf0641cb2010-04-30 14:32:18 +01001110 struct keyring_list *klist;
1111
1112 klist = rcu_dereference_locked_keyring(keyring);
David Howells31204ed2006-06-26 00:24:51 -07001113
1114 /* adjust the quota */
1115 key_payload_reserve(keyring, 0);
1116
1117 if (klist) {
1118 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1119 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1120 }
David Howellsa8b17ed2011-01-20 16:38:27 +00001121}
David Howells5d135442009-09-02 09:14:00 +01001122
1123/*
David Howells973c9f42011-01-20 16:38:33 +00001124 * Determine whether a key is dead.
David Howells5d135442009-09-02 09:14:00 +01001125 */
1126static bool key_is_dead(struct key *key, time_t limit)
1127{
1128 return test_bit(KEY_FLAG_DEAD, &key->flags) ||
1129 (key->expiry > 0 && key->expiry <= limit);
1130}
1131
1132/*
David Howells973c9f42011-01-20 16:38:33 +00001133 * Collect garbage from the contents of a keyring, replacing the old list with
1134 * a new one with the pointers all shuffled down.
1135 *
1136 * Dead keys are classed as oned that are flagged as being dead or are revoked,
1137 * expired or negative keys that were revoked or expired before the specified
1138 * limit.
David Howells5d135442009-09-02 09:14:00 +01001139 */
1140void keyring_gc(struct key *keyring, time_t limit)
1141{
1142 struct keyring_list *klist, *new;
1143 struct key *key;
1144 int loop, keep, max;
1145
David Howellsc08ef802009-09-14 17:26:13 +01001146 kenter("{%x,%s}", key_serial(keyring), keyring->description);
David Howells5d135442009-09-02 09:14:00 +01001147
1148 down_write(&keyring->sem);
1149
David Howellsf0641cb2010-04-30 14:32:18 +01001150 klist = rcu_dereference_locked_keyring(keyring);
David Howells5d135442009-09-02 09:14:00 +01001151 if (!klist)
David Howellsc08ef802009-09-14 17:26:13 +01001152 goto no_klist;
David Howells5d135442009-09-02 09:14:00 +01001153
1154 /* work out how many subscriptions we're keeping */
1155 keep = 0;
1156 for (loop = klist->nkeys - 1; loop >= 0; loop--)
David Howellsc08ef802009-09-14 17:26:13 +01001157 if (!key_is_dead(klist->keys[loop], limit))
David Howells5d135442009-09-02 09:14:00 +01001158 keep++;
1159
1160 if (keep == klist->nkeys)
1161 goto just_return;
1162
1163 /* allocate a new keyring payload */
1164 max = roundup(keep, 4);
1165 new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *),
1166 GFP_KERNEL);
1167 if (!new)
David Howellsc08ef802009-09-14 17:26:13 +01001168 goto nomem;
David Howells5d135442009-09-02 09:14:00 +01001169 new->maxkeys = max;
1170 new->nkeys = 0;
1171 new->delkey = 0;
1172
1173 /* install the live keys
1174 * - must take care as expired keys may be updated back to life
1175 */
1176 keep = 0;
1177 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
1178 key = klist->keys[loop];
1179 if (!key_is_dead(key, limit)) {
1180 if (keep >= max)
1181 goto discard_new;
1182 new->keys[keep++] = key_get(key);
1183 }
1184 }
1185 new->nkeys = keep;
1186
1187 /* adjust the quota */
1188 key_payload_reserve(keyring,
1189 sizeof(struct keyring_list) +
1190 KEYQUOTA_LINK_BYTES * keep);
1191
1192 if (keep == 0) {
1193 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1194 kfree(new);
1195 } else {
1196 rcu_assign_pointer(keyring->payload.subscriptions, new);
1197 }
1198
1199 up_write(&keyring->sem);
1200
1201 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1202 kleave(" [yes]");
1203 return;
1204
1205discard_new:
1206 new->nkeys = keep;
1207 keyring_clear_rcu_disposal(&new->rcu);
David Howellsc08ef802009-09-14 17:26:13 +01001208 up_write(&keyring->sem);
1209 kleave(" [discard]");
1210 return;
1211
David Howells5d135442009-09-02 09:14:00 +01001212just_return:
1213 up_write(&keyring->sem);
David Howellsc08ef802009-09-14 17:26:13 +01001214 kleave(" [no dead]");
1215 return;
1216
1217no_klist:
1218 up_write(&keyring->sem);
1219 kleave(" [no_klist]");
1220 return;
1221
1222nomem:
1223 up_write(&keyring->sem);
1224 kleave(" [oom]");
David Howells5d135442009-09-02 09:14:00 +01001225}