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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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <asm/uaccess.h>
21#include "internal.h"
22
23/*
24 * when plumbing the depths of the key tree, this sets a hard limit set on how
25 * deep we're willing to go
26 */
27#define KEYRING_SEARCH_MAX_DEPTH 6
28
29/*
30 * we keep all named keyrings in a hash to speed looking them up
31 */
32#define KEYRING_NAME_HASH_SIZE (1 << 5)
33
34static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE];
35static DEFINE_RWLOCK(keyring_name_lock);
36
37static inline unsigned keyring_hash(const char *desc)
38{
39 unsigned bucket = 0;
40
41 for (; *desc; desc++)
42 bucket += (unsigned char) *desc;
43
44 return bucket & (KEYRING_NAME_HASH_SIZE - 1);
45}
46
47/*
48 * the keyring type definition
49 */
50static int keyring_instantiate(struct key *keyring,
51 const void *data, size_t datalen);
Linus Torvalds1da177e2005-04-16 15:20:36 -070052static int keyring_match(const struct key *keyring, const void *criterion);
David Howells31204ed2006-06-26 00:24:51 -070053static void keyring_revoke(struct key *keyring);
Linus Torvalds1da177e2005-04-16 15:20:36 -070054static void keyring_destroy(struct key *keyring);
55static void keyring_describe(const struct key *keyring, struct seq_file *m);
56static long keyring_read(const struct key *keyring,
57 char __user *buffer, size_t buflen);
58
59struct key_type key_type_keyring = {
60 .name = "keyring",
61 .def_datalen = sizeof(struct keyring_list),
62 .instantiate = keyring_instantiate,
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 .match = keyring_match,
David Howells31204ed2006-06-26 00:24:51 -070064 .revoke = keyring_revoke,
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 .destroy = keyring_destroy,
66 .describe = keyring_describe,
67 .read = keyring_read,
68};
69
David Howells73182262007-04-26 15:46:23 -070070EXPORT_SYMBOL(key_type_keyring);
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072/*
73 * semaphore to serialise link/link calls to prevent two link calls in parallel
74 * introducing a cycle
75 */
Adrian Bunk1ae8f402006-01-06 00:11:25 -080076static DECLARE_RWSEM(keyring_serialise_link_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -070077
78/*****************************************************************************/
79/*
80 * publish the name of a keyring so that it can be found by name (if it has
81 * one)
82 */
David Howells69664cf2008-04-29 01:01:31 -070083static void keyring_publish_name(struct key *keyring)
Linus Torvalds1da177e2005-04-16 15:20:36 -070084{
85 int bucket;
86
87 if (keyring->description) {
88 bucket = keyring_hash(keyring->description);
89
90 write_lock(&keyring_name_lock);
91
92 if (!keyring_name_hash[bucket].next)
93 INIT_LIST_HEAD(&keyring_name_hash[bucket]);
94
95 list_add_tail(&keyring->type_data.link,
96 &keyring_name_hash[bucket]);
97
98 write_unlock(&keyring_name_lock);
99 }
100
101} /* end keyring_publish_name() */
102
103/*****************************************************************************/
104/*
105 * initialise a keyring
106 * - we object if we were given any data
107 */
108static int keyring_instantiate(struct key *keyring,
109 const void *data, size_t datalen)
110{
111 int ret;
112
113 ret = -EINVAL;
114 if (datalen == 0) {
115 /* make the keyring available by name if it has one */
116 keyring_publish_name(keyring);
117 ret = 0;
118 }
119
120 return ret;
121
122} /* end keyring_instantiate() */
123
124/*****************************************************************************/
125/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 * match keyrings on their name
127 */
128static int keyring_match(const struct key *keyring, const void *description)
129{
130 return keyring->description &&
131 strcmp(keyring->description, description) == 0;
132
133} /* end keyring_match() */
134
135/*****************************************************************************/
136/*
137 * dispose of the data dangling from the corpse of a keyring
138 */
139static void keyring_destroy(struct key *keyring)
140{
141 struct keyring_list *klist;
142 int loop;
143
144 if (keyring->description) {
145 write_lock(&keyring_name_lock);
David Howells94efe722005-08-04 13:07:07 -0700146
147 if (keyring->type_data.link.next != NULL &&
148 !list_empty(&keyring->type_data.link))
149 list_del(&keyring->type_data.link);
150
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 write_unlock(&keyring_name_lock);
152 }
153
David Howells76d8aea2005-06-23 22:00:49 -0700154 klist = rcu_dereference(keyring->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 if (klist) {
156 for (loop = klist->nkeys - 1; loop >= 0; loop--)
157 key_put(klist->keys[loop]);
158 kfree(klist);
159 }
160
161} /* end keyring_destroy() */
162
163/*****************************************************************************/
164/*
165 * describe the keyring
166 */
167static void keyring_describe(const struct key *keyring, struct seq_file *m)
168{
169 struct keyring_list *klist;
170
171 if (keyring->description) {
172 seq_puts(m, keyring->description);
173 }
174 else {
175 seq_puts(m, "[anon]");
176 }
177
David Howells76d8aea2005-06-23 22:00:49 -0700178 rcu_read_lock();
179 klist = rcu_dereference(keyring->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 if (klist)
181 seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
182 else
183 seq_puts(m, ": empty");
David Howells76d8aea2005-06-23 22:00:49 -0700184 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185
186} /* end keyring_describe() */
187
188/*****************************************************************************/
189/*
190 * read a list of key IDs from the keyring's contents
David Howells76d8aea2005-06-23 22:00:49 -0700191 * - the keyring's semaphore is read-locked
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 Howells76d8aea2005-06-23 22:00:49 -0700202 klist = rcu_dereference(keyring->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203
204 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
238 error:
239 return ret;
240
241} /* end keyring_read() */
242
243/*****************************************************************************/
244/*
245 * allocate a keyring and link into the destination keyring
246 */
247struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
David Howellsd84f4f92008-11-14 10:39:23 +1100248 const struct cred *cred, unsigned long flags,
Michael LeMayd7200242006-06-22 14:47:17 -0700249 struct key *dest)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250{
251 struct key *keyring;
252 int ret;
253
254 keyring = key_alloc(&key_type_keyring, description,
David Howellsd84f4f92008-11-14 10:39:23 +1100255 uid, gid, cred,
David Howells29db9192005-10-30 15:02:44 -0800256 (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
David Howells7e047ef2006-06-26 00:24:50 -0700257 flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
259 if (!IS_ERR(keyring)) {
David Howells3e301482005-06-23 22:00:56 -0700260 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 if (ret < 0) {
262 key_put(keyring);
263 keyring = ERR_PTR(ret);
264 }
265 }
266
267 return keyring;
268
269} /* end keyring_alloc() */
270
271/*****************************************************************************/
272/*
273 * search the supplied keyring tree for a key that matches the criterion
274 * - perform a breadth-then-depth search up to the prescribed limit
275 * - we only find keys on which we have search permission
276 * - we use the supplied match function to see if the description (or other
277 * feature of interest) matches
David Howells3e301482005-06-23 22:00:56 -0700278 * - we rely on RCU to prevent the keyring lists from disappearing on us
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 * - we return -EAGAIN if we didn't find any matching key
280 * - we return -ENOKEY if we only found negative matching keys
David Howells664cceb2005-09-28 17:03:15 +0100281 * - we propagate the possession attribute from the keyring ref to the key ref
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 */
David Howells664cceb2005-09-28 17:03:15 +0100283key_ref_t keyring_search_aux(key_ref_t keyring_ref,
David Howellsd84f4f92008-11-14 10:39:23 +1100284 const struct cred *cred,
David Howells664cceb2005-09-28 17:03:15 +0100285 struct key_type *type,
286 const void *description,
287 key_match_func_t match)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288{
289 struct {
David Howells76d8aea2005-06-23 22:00:49 -0700290 struct keyring_list *keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 int kix;
292 } stack[KEYRING_SEARCH_MAX_DEPTH];
293
294 struct keyring_list *keylist;
295 struct timespec now;
Kevin Coffmandceba992008-04-29 01:01:22 -0700296 unsigned long possessed, kflags;
David Howells664cceb2005-09-28 17:03:15 +0100297 struct key *keyring, *key;
298 key_ref_t key_ref;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 long err;
David Howells76d8aea2005-06-23 22:00:49 -0700300 int sp, kix;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301
David Howells664cceb2005-09-28 17:03:15 +0100302 keyring = key_ref_to_ptr(keyring_ref);
303 possessed = is_key_possessed(keyring_ref);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 key_check(keyring);
305
306 /* top keyring must have search permission to begin the search */
David Howellsd84f4f92008-11-14 10:39:23 +1100307 err = key_task_permission(keyring_ref, cred, KEY_SEARCH);
David Howells29db9192005-10-30 15:02:44 -0800308 if (err < 0) {
309 key_ref = ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 goto error;
David Howells29db9192005-10-30 15:02:44 -0800311 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312
David Howells664cceb2005-09-28 17:03:15 +0100313 key_ref = ERR_PTR(-ENOTDIR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 if (keyring->type != &key_type_keyring)
315 goto error;
316
David Howells664cceb2005-09-28 17:03:15 +0100317 rcu_read_lock();
318
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 now = current_kernel_time();
320 err = -EAGAIN;
321 sp = 0;
322
Kevin Coffmandceba992008-04-29 01:01:22 -0700323 /* firstly we should check to see if this top-level keyring is what we
324 * are looking for */
325 key_ref = ERR_PTR(-EAGAIN);
326 kflags = keyring->flags;
327 if (keyring->type == type && match(keyring, description)) {
328 key = keyring;
329
330 /* check it isn't negative and hasn't expired or been
331 * revoked */
332 if (kflags & (1 << KEY_FLAG_REVOKED))
333 goto error_2;
334 if (key->expiry && now.tv_sec >= key->expiry)
335 goto error_2;
336 key_ref = ERR_PTR(-ENOKEY);
337 if (kflags & (1 << KEY_FLAG_NEGATIVE))
338 goto error_2;
339 goto found;
340 }
341
342 /* otherwise, the top keyring must not be revoked, expired, or
343 * negatively instantiated if we are to search it */
344 key_ref = ERR_PTR(-EAGAIN);
345 if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) ||
346 (keyring->expiry && now.tv_sec >= keyring->expiry))
347 goto error_2;
348
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 /* start processing a new keyring */
David Howells664cceb2005-09-28 17:03:15 +0100350descend:
David Howells76d8aea2005-06-23 22:00:49 -0700351 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 goto not_this_keyring;
353
David Howells76d8aea2005-06-23 22:00:49 -0700354 keylist = rcu_dereference(keyring->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 if (!keylist)
356 goto not_this_keyring;
357
358 /* iterate through the keys in this keyring first */
359 for (kix = 0; kix < keylist->nkeys; kix++) {
360 key = keylist->keys[kix];
Kevin Coffmandceba992008-04-29 01:01:22 -0700361 kflags = key->flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362
363 /* ignore keys not of this type */
364 if (key->type != type)
365 continue;
366
367 /* skip revoked keys and expired keys */
Kevin Coffmandceba992008-04-29 01:01:22 -0700368 if (kflags & (1 << KEY_FLAG_REVOKED))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 continue;
370
371 if (key->expiry && now.tv_sec >= key->expiry)
372 continue;
373
374 /* keys that don't match */
375 if (!match(key, description))
376 continue;
377
378 /* key must have search permissions */
David Howells29db9192005-10-30 15:02:44 -0800379 if (key_task_permission(make_key_ref(key, possessed),
David Howellsd84f4f92008-11-14 10:39:23 +1100380 cred, KEY_SEARCH) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 continue;
382
Kevin Coffmandceba992008-04-29 01:01:22 -0700383 /* we set a different error code if we pass a negative key */
384 if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 err = -ENOKEY;
386 continue;
387 }
388
389 goto found;
390 }
391
392 /* search through the keyrings nested in this one */
393 kix = 0;
David Howells664cceb2005-09-28 17:03:15 +0100394ascend:
David Howells76d8aea2005-06-23 22:00:49 -0700395 for (; kix < keylist->nkeys; kix++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 key = keylist->keys[kix];
397 if (key->type != &key_type_keyring)
David Howells76d8aea2005-06-23 22:00:49 -0700398 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399
400 /* recursively search nested keyrings
401 * - only search keyrings for which we have search permission
402 */
403 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
David Howells76d8aea2005-06-23 22:00:49 -0700404 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405
David Howells0f6ed7c2005-11-07 00:59:30 -0800406 if (key_task_permission(make_key_ref(key, possessed),
David Howellsd84f4f92008-11-14 10:39:23 +1100407 cred, KEY_SEARCH) < 0)
David Howells76d8aea2005-06-23 22:00:49 -0700408 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409
410 /* stack the current position */
David Howells76d8aea2005-06-23 22:00:49 -0700411 stack[sp].keylist = keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 stack[sp].kix = kix;
413 sp++;
414
415 /* begin again with the new keyring */
416 keyring = key;
417 goto descend;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 }
419
420 /* the keyring we're looking at was disqualified or didn't contain a
421 * matching key */
David Howells664cceb2005-09-28 17:03:15 +0100422not_this_keyring:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 if (sp > 0) {
424 /* resume the processing of a keyring higher up in the tree */
425 sp--;
David Howells76d8aea2005-06-23 22:00:49 -0700426 keylist = stack[sp].keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 kix = stack[sp].kix + 1;
428 goto ascend;
429 }
430
David Howells664cceb2005-09-28 17:03:15 +0100431 key_ref = ERR_PTR(err);
432 goto error_2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433
434 /* we found a viable match */
David Howells664cceb2005-09-28 17:03:15 +0100435found:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 atomic_inc(&key->usage);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 key_check(key);
David Howells664cceb2005-09-28 17:03:15 +0100438 key_ref = make_key_ref(key, possessed);
439error_2:
David Howells76d8aea2005-06-23 22:00:49 -0700440 rcu_read_unlock();
David Howells664cceb2005-09-28 17:03:15 +0100441error:
442 return key_ref;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443
444} /* end keyring_search_aux() */
445
446/*****************************************************************************/
447/*
448 * search the supplied keyring tree for a key that matches the criterion
449 * - perform a breadth-then-depth search up to the prescribed limit
450 * - we only find keys on which we have search permission
451 * - we readlock the keyrings as we search down the tree
452 * - we return -EAGAIN if we didn't find any matching key
453 * - we return -ENOKEY if we only found negative matching keys
454 */
David Howells664cceb2005-09-28 17:03:15 +0100455key_ref_t keyring_search(key_ref_t keyring,
456 struct key_type *type,
457 const char *description)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458{
David Howells3e301482005-06-23 22:00:56 -0700459 if (!type->match)
460 return ERR_PTR(-ENOKEY);
461
David Howellsd84f4f92008-11-14 10:39:23 +1100462 return keyring_search_aux(keyring, current->cred,
David Howells3e301482005-06-23 22:00:56 -0700463 type, description, type->match);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464
465} /* end keyring_search() */
466
467EXPORT_SYMBOL(keyring_search);
468
469/*****************************************************************************/
470/*
471 * search the given keyring only (no recursion)
472 * - keyring must be locked by caller
David Howellsc3a9d652006-04-10 15:15:21 +0100473 * - caller must guarantee that the keyring is a keyring
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 */
David Howells664cceb2005-09-28 17:03:15 +0100475key_ref_t __keyring_search_one(key_ref_t keyring_ref,
476 const struct key_type *ktype,
477 const char *description,
478 key_perm_t perm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479{
480 struct keyring_list *klist;
David Howells664cceb2005-09-28 17:03:15 +0100481 unsigned long possessed;
482 struct key *keyring, *key;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 int loop;
484
David Howells664cceb2005-09-28 17:03:15 +0100485 keyring = key_ref_to_ptr(keyring_ref);
486 possessed = is_key_possessed(keyring_ref);
487
David Howells76d8aea2005-06-23 22:00:49 -0700488 rcu_read_lock();
489
490 klist = rcu_dereference(keyring->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 if (klist) {
492 for (loop = 0; loop < klist->nkeys; loop++) {
493 key = klist->keys[loop];
494
495 if (key->type == ktype &&
David Howells3e301482005-06-23 22:00:56 -0700496 (!key->type->match ||
497 key->type->match(key, description)) &&
David Howells664cceb2005-09-28 17:03:15 +0100498 key_permission(make_key_ref(key, possessed),
David Howellsdb1d1d52005-12-01 00:51:18 -0800499 perm) == 0 &&
David Howells76d8aea2005-06-23 22:00:49 -0700500 !test_bit(KEY_FLAG_REVOKED, &key->flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 )
502 goto found;
503 }
504 }
505
David Howells664cceb2005-09-28 17:03:15 +0100506 rcu_read_unlock();
507 return ERR_PTR(-ENOKEY);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508
509 found:
510 atomic_inc(&key->usage);
David Howells76d8aea2005-06-23 22:00:49 -0700511 rcu_read_unlock();
David Howells664cceb2005-09-28 17:03:15 +0100512 return make_key_ref(key, possessed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513
514} /* end __keyring_search_one() */
515
516/*****************************************************************************/
517/*
518 * find a keyring with the specified name
519 * - all named keyrings are searched
David Howells69664cf2008-04-29 01:01:31 -0700520 * - normally only finds keyrings with search permission for the current process
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 */
David Howells69664cf2008-04-29 01:01:31 -0700522struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523{
524 struct key *keyring;
525 int bucket;
526
527 keyring = ERR_PTR(-EINVAL);
528 if (!name)
529 goto error;
530
531 bucket = keyring_hash(name);
532
533 read_lock(&keyring_name_lock);
534
535 if (keyring_name_hash[bucket].next) {
536 /* search this hash bucket for a keyring with a matching name
537 * that's readable and that hasn't been revoked */
538 list_for_each_entry(keyring,
539 &keyring_name_hash[bucket],
540 type_data.link
541 ) {
David Howells76d8aea2005-06-23 22:00:49 -0700542 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543 continue;
544
545 if (strcmp(keyring->description, name) != 0)
546 continue;
547
David Howells69664cf2008-04-29 01:01:31 -0700548 if (!skip_perm_check &&
549 key_permission(make_key_ref(keyring, 0),
David Howells0f6ed7c2005-11-07 00:59:30 -0800550 KEY_SEARCH) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 continue;
552
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 /* we've got a match */
554 atomic_inc(&keyring->usage);
555 read_unlock(&keyring_name_lock);
556 goto error;
557 }
558 }
559
560 read_unlock(&keyring_name_lock);
561 keyring = ERR_PTR(-ENOKEY);
562
563 error:
564 return keyring;
565
566} /* end find_keyring_by_name() */
567
568/*****************************************************************************/
569/*
570 * see if a cycle will will be created by inserting acyclic tree B in acyclic
571 * tree A at the topmost level (ie: as a direct child of A)
572 * - since we are adding B to A at the top level, checking for cycles should
573 * just be a matter of seeing if node A is somewhere in tree B
574 */
575static int keyring_detect_cycle(struct key *A, struct key *B)
576{
577 struct {
David Howells76d8aea2005-06-23 22:00:49 -0700578 struct keyring_list *keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 int kix;
580 } stack[KEYRING_SEARCH_MAX_DEPTH];
581
582 struct keyring_list *keylist;
583 struct key *subtree, *key;
584 int sp, kix, ret;
585
David Howells76d8aea2005-06-23 22:00:49 -0700586 rcu_read_lock();
587
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588 ret = -EDEADLK;
589 if (A == B)
David Howells76d8aea2005-06-23 22:00:49 -0700590 goto cycle_detected;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591
592 subtree = B;
593 sp = 0;
594
595 /* start processing a new keyring */
596 descend:
David Howells76d8aea2005-06-23 22:00:49 -0700597 if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 goto not_this_keyring;
599
David Howells76d8aea2005-06-23 22:00:49 -0700600 keylist = rcu_dereference(subtree->payload.subscriptions);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 if (!keylist)
602 goto not_this_keyring;
603 kix = 0;
604
605 ascend:
606 /* iterate through the remaining keys in this keyring */
607 for (; kix < keylist->nkeys; kix++) {
608 key = keylist->keys[kix];
609
610 if (key == A)
611 goto cycle_detected;
612
613 /* recursively check nested keyrings */
614 if (key->type == &key_type_keyring) {
615 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
616 goto too_deep;
617
618 /* stack the current position */
David Howells76d8aea2005-06-23 22:00:49 -0700619 stack[sp].keylist = keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 stack[sp].kix = kix;
621 sp++;
622
623 /* begin again with the new keyring */
624 subtree = key;
625 goto descend;
626 }
627 }
628
629 /* the keyring we're looking at was disqualified or didn't contain a
630 * matching key */
631 not_this_keyring:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 if (sp > 0) {
633 /* resume the checking of a keyring higher up in the tree */
634 sp--;
David Howells76d8aea2005-06-23 22:00:49 -0700635 keylist = stack[sp].keylist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 kix = stack[sp].kix + 1;
637 goto ascend;
638 }
639
640 ret = 0; /* no cycles detected */
641
642 error:
David Howells76d8aea2005-06-23 22:00:49 -0700643 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 return ret;
645
646 too_deep:
647 ret = -ELOOP;
David Howells76d8aea2005-06-23 22:00:49 -0700648 goto error;
649
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 cycle_detected:
651 ret = -EDEADLK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 goto error;
653
654} /* end keyring_detect_cycle() */
655
656/*****************************************************************************/
657/*
David Howells76d8aea2005-06-23 22:00:49 -0700658 * dispose of a keyring list after the RCU grace period
659 */
660static void keyring_link_rcu_disposal(struct rcu_head *rcu)
661{
662 struct keyring_list *klist =
663 container_of(rcu, struct keyring_list, rcu);
664
665 kfree(klist);
666
667} /* end keyring_link_rcu_disposal() */
668
669/*****************************************************************************/
670/*
David Howellscab8eb52006-01-08 01:02:45 -0800671 * dispose of a keyring list after the RCU grace period, freeing the unlinked
672 * key
673 */
674static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
675{
676 struct keyring_list *klist =
677 container_of(rcu, struct keyring_list, rcu);
678
679 key_put(klist->keys[klist->delkey]);
680 kfree(klist);
681
682} /* end keyring_unlink_rcu_disposal() */
683
684/*****************************************************************************/
685/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 * link a key into to a keyring
David Howells76d8aea2005-06-23 22:00:49 -0700687 * - must be called with the keyring's semaphore write-locked
David Howellscab8eb52006-01-08 01:02:45 -0800688 * - discard already extant link to matching key if there is one
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689 */
690int __key_link(struct key *keyring, struct key *key)
691{
692 struct keyring_list *klist, *nklist;
693 unsigned max;
694 size_t size;
David Howellscab8eb52006-01-08 01:02:45 -0800695 int loop, ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696
697 ret = -EKEYREVOKED;
David Howells76d8aea2005-06-23 22:00:49 -0700698 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 goto error;
700
701 ret = -ENOTDIR;
702 if (keyring->type != &key_type_keyring)
703 goto error;
704
705 /* serialise link/link calls to prevent parallel calls causing a
706 * cycle when applied to two keyring in opposite orders */
707 down_write(&keyring_serialise_link_sem);
708
709 /* check that we aren't going to create a cycle adding one keyring to
710 * another */
711 if (key->type == &key_type_keyring) {
712 ret = keyring_detect_cycle(keyring, key);
713 if (ret < 0)
714 goto error2;
715 }
716
David Howellscab8eb52006-01-08 01:02:45 -0800717 /* see if there's a matching key we can displace */
718 klist = keyring->payload.subscriptions;
719
720 if (klist && klist->nkeys > 0) {
721 struct key_type *type = key->type;
722
723 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
724 if (klist->keys[loop]->type == type &&
725 strcmp(klist->keys[loop]->description,
726 key->description) == 0
727 ) {
728 /* found a match - replace with new key */
729 size = sizeof(struct key *) * klist->maxkeys;
730 size += sizeof(*klist);
731 BUG_ON(size > PAGE_SIZE);
732
733 ret = -ENOMEM;
Eric Sesterhenn48ad5042006-12-06 20:33:47 -0800734 nklist = kmemdup(klist, size, GFP_KERNEL);
David Howellscab8eb52006-01-08 01:02:45 -0800735 if (!nklist)
736 goto error2;
737
David Howellscab8eb52006-01-08 01:02:45 -0800738 /* replace matched key */
739 atomic_inc(&key->usage);
740 nklist->keys[loop] = key;
741
742 rcu_assign_pointer(
743 keyring->payload.subscriptions,
744 nklist);
745
746 /* dispose of the old keyring list and the
747 * displaced key */
748 klist->delkey = loop;
749 call_rcu(&klist->rcu,
750 keyring_unlink_rcu_disposal);
751
752 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)
761 goto error2;
762
763 klist = keyring->payload.subscriptions;
764
765 if (klist && klist->nkeys < klist->maxkeys) {
766 /* there's sufficient slack space to add directly */
767 atomic_inc(&key->usage);
768
David Howells76d8aea2005-06-23 22:00:49 -0700769 klist->keys[klist->nkeys] = key;
770 smp_wmb();
771 klist->nkeys++;
772 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 }
774 else {
775 /* grow the key list */
776 max = 4;
777 if (klist)
778 max += klist->maxkeys;
779
780 ret = -ENFILE;
David Howells76d8aea2005-06-23 22:00:49 -0700781 if (max > 65535)
782 goto error3;
David Howellsa4014d82005-07-07 17:57:03 -0700783 size = sizeof(*klist) + sizeof(struct key *) * max;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 if (size > PAGE_SIZE)
785 goto error3;
786
787 ret = -ENOMEM;
788 nklist = kmalloc(size, GFP_KERNEL);
789 if (!nklist)
790 goto error3;
791 nklist->maxkeys = max;
792 nklist->nkeys = 0;
793
794 if (klist) {
795 nklist->nkeys = klist->nkeys;
796 memcpy(nklist->keys,
797 klist->keys,
798 sizeof(struct key *) * klist->nkeys);
799 }
800
801 /* add the key into the new space */
802 atomic_inc(&key->usage);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700803 nklist->keys[nklist->nkeys++] = key;
David Howells76d8aea2005-06-23 22:00:49 -0700804
805 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806
807 /* dispose of the old keyring list */
David Howells76d8aea2005-06-23 22:00:49 -0700808 if (klist)
809 call_rcu(&klist->rcu, keyring_link_rcu_disposal);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810 }
811
David Howellscab8eb52006-01-08 01:02:45 -0800812done:
813 ret = 0;
814error2:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815 up_write(&keyring_serialise_link_sem);
David Howellscab8eb52006-01-08 01:02:45 -0800816error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817 return ret;
818
David Howellscab8eb52006-01-08 01:02:45 -0800819error3:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820 /* undo the quota changes */
821 key_payload_reserve(keyring,
822 keyring->datalen - KEYQUOTA_LINK_BYTES);
823 goto error2;
824
825} /* end __key_link() */
826
827/*****************************************************************************/
828/*
829 * link a key to a keyring
830 */
831int key_link(struct key *keyring, struct key *key)
832{
833 int ret;
834
835 key_check(keyring);
836 key_check(key);
837
838 down_write(&keyring->sem);
839 ret = __key_link(keyring, key);
840 up_write(&keyring->sem);
841
842 return ret;
843
844} /* end key_link() */
845
846EXPORT_SYMBOL(key_link);
847
848/*****************************************************************************/
849/*
850 * unlink the first link to a key from a keyring
851 */
852int key_unlink(struct key *keyring, struct key *key)
853{
David Howells76d8aea2005-06-23 22:00:49 -0700854 struct keyring_list *klist, *nklist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 int loop, ret;
856
857 key_check(keyring);
858 key_check(key);
859
860 ret = -ENOTDIR;
861 if (keyring->type != &key_type_keyring)
862 goto error;
863
864 down_write(&keyring->sem);
865
866 klist = keyring->payload.subscriptions;
867 if (klist) {
868 /* search the keyring for the key */
869 for (loop = 0; loop < klist->nkeys; loop++)
870 if (klist->keys[loop] == key)
871 goto key_is_present;
872 }
873
874 up_write(&keyring->sem);
875 ret = -ENOENT;
876 goto error;
877
David Howells76d8aea2005-06-23 22:00:49 -0700878key_is_present:
879 /* we need to copy the key list for RCU purposes */
David Howellsa4014d82005-07-07 17:57:03 -0700880 nklist = kmalloc(sizeof(*klist) +
881 sizeof(struct key *) * klist->maxkeys,
David Howells76d8aea2005-06-23 22:00:49 -0700882 GFP_KERNEL);
883 if (!nklist)
884 goto nomem;
885 nklist->maxkeys = klist->maxkeys;
886 nklist->nkeys = klist->nkeys - 1;
887
888 if (loop > 0)
889 memcpy(&nklist->keys[0],
890 &klist->keys[0],
David Howellsa4014d82005-07-07 17:57:03 -0700891 loop * sizeof(struct key *));
David Howells76d8aea2005-06-23 22:00:49 -0700892
893 if (loop < nklist->nkeys)
894 memcpy(&nklist->keys[loop],
895 &klist->keys[loop + 1],
David Howellsa4014d82005-07-07 17:57:03 -0700896 (nklist->nkeys - loop) * sizeof(struct key *));
David Howells76d8aea2005-06-23 22:00:49 -0700897
Linus Torvalds1da177e2005-04-16 15:20:36 -0700898 /* adjust the user's quota */
899 key_payload_reserve(keyring,
900 keyring->datalen - KEYQUOTA_LINK_BYTES);
901
David Howells76d8aea2005-06-23 22:00:49 -0700902 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903
904 up_write(&keyring->sem);
David Howells76d8aea2005-06-23 22:00:49 -0700905
906 /* schedule for later cleanup */
907 klist->delkey = loop;
908 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
909
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 ret = 0;
911
David Howells76d8aea2005-06-23 22:00:49 -0700912error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913 return ret;
David Howells76d8aea2005-06-23 22:00:49 -0700914nomem:
915 ret = -ENOMEM;
916 up_write(&keyring->sem);
917 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700918
919} /* end key_unlink() */
920
921EXPORT_SYMBOL(key_unlink);
922
923/*****************************************************************************/
924/*
David Howells76d8aea2005-06-23 22:00:49 -0700925 * dispose of a keyring list after the RCU grace period, releasing the keys it
926 * links to
927 */
928static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
929{
930 struct keyring_list *klist;
931 int loop;
932
933 klist = container_of(rcu, struct keyring_list, rcu);
934
935 for (loop = klist->nkeys - 1; loop >= 0; loop--)
936 key_put(klist->keys[loop]);
937
938 kfree(klist);
939
940} /* end keyring_clear_rcu_disposal() */
941
942/*****************************************************************************/
943/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 * clear the specified process keyring
945 * - implements keyctl(KEYCTL_CLEAR)
946 */
947int keyring_clear(struct key *keyring)
948{
949 struct keyring_list *klist;
David Howells76d8aea2005-06-23 22:00:49 -0700950 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951
952 ret = -ENOTDIR;
953 if (keyring->type == &key_type_keyring) {
954 /* detach the pointer block with the locks held */
955 down_write(&keyring->sem);
956
957 klist = keyring->payload.subscriptions;
958 if (klist) {
959 /* adjust the quota */
960 key_payload_reserve(keyring,
961 sizeof(struct keyring_list));
962
David Howells76d8aea2005-06-23 22:00:49 -0700963 rcu_assign_pointer(keyring->payload.subscriptions,
964 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965 }
966
967 up_write(&keyring->sem);
968
969 /* free the keys after the locks have been dropped */
David Howells76d8aea2005-06-23 22:00:49 -0700970 if (klist)
971 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972
973 ret = 0;
974 }
975
976 return ret;
977
978} /* end keyring_clear() */
979
980EXPORT_SYMBOL(keyring_clear);
David Howells31204ed2006-06-26 00:24:51 -0700981
982/*****************************************************************************/
983/*
984 * dispose of the links from a revoked keyring
985 * - called with the key sem write-locked
986 */
987static void keyring_revoke(struct key *keyring)
988{
989 struct keyring_list *klist = keyring->payload.subscriptions;
990
991 /* adjust the quota */
992 key_payload_reserve(keyring, 0);
993
994 if (klist) {
995 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
996 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
997 }
998
999} /* end keyring_revoke() */