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TOMOYO Linux Cross Reference
Linux/security/keys/key.c

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  1 /* Basic authentication token and access key management
  2  *
  3  * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
  4  * 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/poison.h>
 15 #include <linux/sched.h>
 16 #include <linux/slab.h>
 17 #include <linux/security.h>
 18 #include <linux/workqueue.h>
 19 #include <linux/random.h>
 20 #include <linux/err.h>
 21 #include "internal.h"
 22 
 23 struct kmem_cache *key_jar;
 24 struct rb_root          key_serial_tree; /* tree of keys indexed by serial */
 25 DEFINE_SPINLOCK(key_serial_lock);
 26 
 27 struct rb_root  key_user_tree; /* tree of quota records indexed by UID */
 28 DEFINE_SPINLOCK(key_user_lock);
 29 
 30 unsigned int key_quota_root_maxkeys = 1000000;  /* root's key count quota */
 31 unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
 32 unsigned int key_quota_maxkeys = 200;           /* general key count quota */
 33 unsigned int key_quota_maxbytes = 20000;        /* general key space quota */
 34 
 35 static LIST_HEAD(key_types_list);
 36 static DECLARE_RWSEM(key_types_sem);
 37 
 38 /* We serialise key instantiation and link */
 39 DEFINE_MUTEX(key_construction_mutex);
 40 
 41 #ifdef KEY_DEBUGGING
 42 void __key_check(const struct key *key)
 43 {
 44         printk("__key_check: key %p {%08x} should be {%08x}\n",
 45                key, key->magic, KEY_DEBUG_MAGIC);
 46         BUG();
 47 }
 48 #endif
 49 
 50 /*
 51  * Get the key quota record for a user, allocating a new record if one doesn't
 52  * already exist.
 53  */
 54 struct key_user *key_user_lookup(kuid_t uid)
 55 {
 56         struct key_user *candidate = NULL, *user;
 57         struct rb_node *parent = NULL;
 58         struct rb_node **p;
 59 
 60 try_again:
 61         p = &key_user_tree.rb_node;
 62         spin_lock(&key_user_lock);
 63 
 64         /* search the tree for a user record with a matching UID */
 65         while (*p) {
 66                 parent = *p;
 67                 user = rb_entry(parent, struct key_user, node);
 68 
 69                 if (uid_lt(uid, user->uid))
 70                         p = &(*p)->rb_left;
 71                 else if (uid_gt(uid, user->uid))
 72                         p = &(*p)->rb_right;
 73                 else
 74                         goto found;
 75         }
 76 
 77         /* if we get here, we failed to find a match in the tree */
 78         if (!candidate) {
 79                 /* allocate a candidate user record if we don't already have
 80                  * one */
 81                 spin_unlock(&key_user_lock);
 82 
 83                 user = NULL;
 84                 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
 85                 if (unlikely(!candidate))
 86                         goto out;
 87 
 88                 /* the allocation may have scheduled, so we need to repeat the
 89                  * search lest someone else added the record whilst we were
 90                  * asleep */
 91                 goto try_again;
 92         }
 93 
 94         /* if we get here, then the user record still hadn't appeared on the
 95          * second pass - so we use the candidate record */
 96         atomic_set(&candidate->usage, 1);
 97         atomic_set(&candidate->nkeys, 0);
 98         atomic_set(&candidate->nikeys, 0);
 99         candidate->uid = uid;
100         candidate->qnkeys = 0;
101         candidate->qnbytes = 0;
102         spin_lock_init(&candidate->lock);
103         mutex_init(&candidate->cons_lock);
104 
105         rb_link_node(&candidate->node, parent, p);
106         rb_insert_color(&candidate->node, &key_user_tree);
107         spin_unlock(&key_user_lock);
108         user = candidate;
109         goto out;
110 
111         /* okay - we found a user record for this UID */
112 found:
113         atomic_inc(&user->usage);
114         spin_unlock(&key_user_lock);
115         kfree(candidate);
116 out:
117         return user;
118 }
119 
120 /*
121  * Dispose of a user structure
122  */
123 void key_user_put(struct key_user *user)
124 {
125         if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
126                 rb_erase(&user->node, &key_user_tree);
127                 spin_unlock(&key_user_lock);
128 
129                 kfree(user);
130         }
131 }
132 
133 /*
134  * Allocate a serial number for a key.  These are assigned randomly to avoid
135  * security issues through covert channel problems.
136  */
137 static inline void key_alloc_serial(struct key *key)
138 {
139         struct rb_node *parent, **p;
140         struct key *xkey;
141 
142         /* propose a random serial number and look for a hole for it in the
143          * serial number tree */
144         do {
145                 get_random_bytes(&key->serial, sizeof(key->serial));
146 
147                 key->serial >>= 1; /* negative numbers are not permitted */
148         } while (key->serial < 3);
149 
150         spin_lock(&key_serial_lock);
151 
152 attempt_insertion:
153         parent = NULL;
154         p = &key_serial_tree.rb_node;
155 
156         while (*p) {
157                 parent = *p;
158                 xkey = rb_entry(parent, struct key, serial_node);
159 
160                 if (key->serial < xkey->serial)
161                         p = &(*p)->rb_left;
162                 else if (key->serial > xkey->serial)
163                         p = &(*p)->rb_right;
164                 else
165                         goto serial_exists;
166         }
167 
168         /* we've found a suitable hole - arrange for this key to occupy it */
169         rb_link_node(&key->serial_node, parent, p);
170         rb_insert_color(&key->serial_node, &key_serial_tree);
171 
172         spin_unlock(&key_serial_lock);
173         return;
174 
175         /* we found a key with the proposed serial number - walk the tree from
176          * that point looking for the next unused serial number */
177 serial_exists:
178         for (;;) {
179                 key->serial++;
180                 if (key->serial < 3) {
181                         key->serial = 3;
182                         goto attempt_insertion;
183                 }
184 
185                 parent = rb_next(parent);
186                 if (!parent)
187                         goto attempt_insertion;
188 
189                 xkey = rb_entry(parent, struct key, serial_node);
190                 if (key->serial < xkey->serial)
191                         goto attempt_insertion;
192         }
193 }
194 
195 /**
196  * key_alloc - Allocate a key of the specified type.
197  * @type: The type of key to allocate.
198  * @desc: The key description to allow the key to be searched out.
199  * @uid: The owner of the new key.
200  * @gid: The group ID for the new key's group permissions.
201  * @cred: The credentials specifying UID namespace.
202  * @perm: The permissions mask of the new key.
203  * @flags: Flags specifying quota properties.
204  *
205  * Allocate a key of the specified type with the attributes given.  The key is
206  * returned in an uninstantiated state and the caller needs to instantiate the
207  * key before returning.
208  *
209  * The user's key count quota is updated to reflect the creation of the key and
210  * the user's key data quota has the default for the key type reserved.  The
211  * instantiation function should amend this as necessary.  If insufficient
212  * quota is available, -EDQUOT will be returned.
213  *
214  * The LSM security modules can prevent a key being created, in which case
215  * -EACCES will be returned.
216  *
217  * Returns a pointer to the new key if successful and an error code otherwise.
218  *
219  * Note that the caller needs to ensure the key type isn't uninstantiated.
220  * Internally this can be done by locking key_types_sem.  Externally, this can
221  * be done by either never unregistering the key type, or making sure
222  * key_alloc() calls don't race with module unloading.
223  */
224 struct key *key_alloc(struct key_type *type, const char *desc,
225                       kuid_t uid, kgid_t gid, const struct cred *cred,
226                       key_perm_t perm, unsigned long flags)
227 {
228         struct key_user *user = NULL;
229         struct key *key;
230         size_t desclen, quotalen;
231         int ret;
232 
233         key = ERR_PTR(-EINVAL);
234         if (!desc || !*desc)
235                 goto error;
236 
237         if (type->vet_description) {
238                 ret = type->vet_description(desc);
239                 if (ret < 0) {
240                         key = ERR_PTR(ret);
241                         goto error;
242                 }
243         }
244 
245         desclen = strlen(desc);
246         quotalen = desclen + 1 + type->def_datalen;
247 
248         /* get hold of the key tracking for this user */
249         user = key_user_lookup(uid);
250         if (!user)
251                 goto no_memory_1;
252 
253         /* check that the user's quota permits allocation of another key and
254          * its description */
255         if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
256                 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
257                         key_quota_root_maxkeys : key_quota_maxkeys;
258                 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
259                         key_quota_root_maxbytes : key_quota_maxbytes;
260 
261                 spin_lock(&user->lock);
262                 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
263                         if (user->qnkeys + 1 >= maxkeys ||
264                             user->qnbytes + quotalen >= maxbytes ||
265                             user->qnbytes + quotalen < user->qnbytes)
266                                 goto no_quota;
267                 }
268 
269                 user->qnkeys++;
270                 user->qnbytes += quotalen;
271                 spin_unlock(&user->lock);
272         }
273 
274         /* allocate and initialise the key and its description */
275         key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
276         if (!key)
277                 goto no_memory_2;
278 
279         key->index_key.desc_len = desclen;
280         key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
281         if (!key->index_key.description)
282                 goto no_memory_3;
283 
284         atomic_set(&key->usage, 1);
285         init_rwsem(&key->sem);
286         lockdep_set_class(&key->sem, &type->lock_class);
287         key->index_key.type = type;
288         key->user = user;
289         key->quotalen = quotalen;
290         key->datalen = type->def_datalen;
291         key->uid = uid;
292         key->gid = gid;
293         key->perm = perm;
294 
295         if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
296                 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
297         if (flags & KEY_ALLOC_TRUSTED)
298                 key->flags |= 1 << KEY_FLAG_TRUSTED;
299         if (flags & KEY_ALLOC_BUILT_IN)
300                 key->flags |= 1 << KEY_FLAG_BUILTIN;
301 
302 #ifdef KEY_DEBUGGING
303         key->magic = KEY_DEBUG_MAGIC;
304 #endif
305 
306         /* let the security module know about the key */
307         ret = security_key_alloc(key, cred, flags);
308         if (ret < 0)
309                 goto security_error;
310 
311         /* publish the key by giving it a serial number */
312         atomic_inc(&user->nkeys);
313         key_alloc_serial(key);
314 
315 error:
316         return key;
317 
318 security_error:
319         kfree(key->description);
320         kmem_cache_free(key_jar, key);
321         if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
322                 spin_lock(&user->lock);
323                 user->qnkeys--;
324                 user->qnbytes -= quotalen;
325                 spin_unlock(&user->lock);
326         }
327         key_user_put(user);
328         key = ERR_PTR(ret);
329         goto error;
330 
331 no_memory_3:
332         kmem_cache_free(key_jar, key);
333 no_memory_2:
334         if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
335                 spin_lock(&user->lock);
336                 user->qnkeys--;
337                 user->qnbytes -= quotalen;
338                 spin_unlock(&user->lock);
339         }
340         key_user_put(user);
341 no_memory_1:
342         key = ERR_PTR(-ENOMEM);
343         goto error;
344 
345 no_quota:
346         spin_unlock(&user->lock);
347         key_user_put(user);
348         key = ERR_PTR(-EDQUOT);
349         goto error;
350 }
351 EXPORT_SYMBOL(key_alloc);
352 
353 /**
354  * key_payload_reserve - Adjust data quota reservation for the key's payload
355  * @key: The key to make the reservation for.
356  * @datalen: The amount of data payload the caller now wants.
357  *
358  * Adjust the amount of the owning user's key data quota that a key reserves.
359  * If the amount is increased, then -EDQUOT may be returned if there isn't
360  * enough free quota available.
361  *
362  * If successful, 0 is returned.
363  */
364 int key_payload_reserve(struct key *key, size_t datalen)
365 {
366         int delta = (int)datalen - key->datalen;
367         int ret = 0;
368 
369         key_check(key);
370 
371         /* contemplate the quota adjustment */
372         if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
373                 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
374                         key_quota_root_maxbytes : key_quota_maxbytes;
375 
376                 spin_lock(&key->user->lock);
377 
378                 if (delta > 0 &&
379                     (key->user->qnbytes + delta >= maxbytes ||
380                      key->user->qnbytes + delta < key->user->qnbytes)) {
381                         ret = -EDQUOT;
382                 }
383                 else {
384                         key->user->qnbytes += delta;
385                         key->quotalen += delta;
386                 }
387                 spin_unlock(&key->user->lock);
388         }
389 
390         /* change the recorded data length if that didn't generate an error */
391         if (ret == 0)
392                 key->datalen = datalen;
393 
394         return ret;
395 }
396 EXPORT_SYMBOL(key_payload_reserve);
397 
398 /*
399  * Instantiate a key and link it into the target keyring atomically.  Must be
400  * called with the target keyring's semaphore writelocked.  The target key's
401  * semaphore need not be locked as instantiation is serialised by
402  * key_construction_mutex.
403  */
404 static int __key_instantiate_and_link(struct key *key,
405                                       struct key_preparsed_payload *prep,
406                                       struct key *keyring,
407                                       struct key *authkey,
408                                       struct assoc_array_edit **_edit)
409 {
410         int ret, awaken;
411 
412         key_check(key);
413         key_check(keyring);
414 
415         awaken = 0;
416         ret = -EBUSY;
417 
418         mutex_lock(&key_construction_mutex);
419 
420         /* can't instantiate twice */
421         if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
422                 /* instantiate the key */
423                 ret = key->type->instantiate(key, prep);
424 
425                 if (ret == 0) {
426                         /* mark the key as being instantiated */
427                         atomic_inc(&key->user->nikeys);
428                         set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
429 
430                         if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
431                                 awaken = 1;
432 
433                         /* and link it into the destination keyring */
434                         if (keyring) {
435                                 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
436                                         set_bit(KEY_FLAG_KEEP, &key->flags);
437 
438                                 __key_link(key, _edit);
439                         }
440 
441                         /* disable the authorisation key */
442                         if (authkey)
443                                 key_revoke(authkey);
444 
445                         if (prep->expiry != TIME_T_MAX) {
446                                 key->expiry = prep->expiry;
447                                 key_schedule_gc(prep->expiry + key_gc_delay);
448                         }
449                 }
450         }
451 
452         mutex_unlock(&key_construction_mutex);
453 
454         /* wake up anyone waiting for a key to be constructed */
455         if (awaken)
456                 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
457 
458         return ret;
459 }
460 
461 /**
462  * key_instantiate_and_link - Instantiate a key and link it into the keyring.
463  * @key: The key to instantiate.
464  * @data: The data to use to instantiate the keyring.
465  * @datalen: The length of @data.
466  * @keyring: Keyring to create a link in on success (or NULL).
467  * @authkey: The authorisation token permitting instantiation.
468  *
469  * Instantiate a key that's in the uninstantiated state using the provided data
470  * and, if successful, link it in to the destination keyring if one is
471  * supplied.
472  *
473  * If successful, 0 is returned, the authorisation token is revoked and anyone
474  * waiting for the key is woken up.  If the key was already instantiated,
475  * -EBUSY will be returned.
476  */
477 int key_instantiate_and_link(struct key *key,
478                              const void *data,
479                              size_t datalen,
480                              struct key *keyring,
481                              struct key *authkey)
482 {
483         struct key_preparsed_payload prep;
484         struct assoc_array_edit *edit;
485         int ret;
486 
487         memset(&prep, 0, sizeof(prep));
488         prep.data = data;
489         prep.datalen = datalen;
490         prep.quotalen = key->type->def_datalen;
491         prep.expiry = TIME_T_MAX;
492         if (key->type->preparse) {
493                 ret = key->type->preparse(&prep);
494                 if (ret < 0)
495                         goto error;
496         }
497 
498         if (keyring) {
499                 ret = __key_link_begin(keyring, &key->index_key, &edit);
500                 if (ret < 0)
501                         goto error;
502         }
503 
504         ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
505 
506         if (keyring)
507                 __key_link_end(keyring, &key->index_key, edit);
508 
509 error:
510         if (key->type->preparse)
511                 key->type->free_preparse(&prep);
512         return ret;
513 }
514 
515 EXPORT_SYMBOL(key_instantiate_and_link);
516 
517 /**
518  * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
519  * @key: The key to instantiate.
520  * @timeout: The timeout on the negative key.
521  * @error: The error to return when the key is hit.
522  * @keyring: Keyring to create a link in on success (or NULL).
523  * @authkey: The authorisation token permitting instantiation.
524  *
525  * Negatively instantiate a key that's in the uninstantiated state and, if
526  * successful, set its timeout and stored error and link it in to the
527  * destination keyring if one is supplied.  The key and any links to the key
528  * will be automatically garbage collected after the timeout expires.
529  *
530  * Negative keys are used to rate limit repeated request_key() calls by causing
531  * them to return the stored error code (typically ENOKEY) until the negative
532  * key expires.
533  *
534  * If successful, 0 is returned, the authorisation token is revoked and anyone
535  * waiting for the key is woken up.  If the key was already instantiated,
536  * -EBUSY will be returned.
537  */
538 int key_reject_and_link(struct key *key,
539                         unsigned timeout,
540                         unsigned error,
541                         struct key *keyring,
542                         struct key *authkey)
543 {
544         struct assoc_array_edit *edit;
545         struct timespec now;
546         int ret, awaken, link_ret = 0;
547 
548         key_check(key);
549         key_check(keyring);
550 
551         awaken = 0;
552         ret = -EBUSY;
553 
554         if (keyring)
555                 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
556 
557         mutex_lock(&key_construction_mutex);
558 
559         /* can't instantiate twice */
560         if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
561                 /* mark the key as being negatively instantiated */
562                 atomic_inc(&key->user->nikeys);
563                 key->reject_error = -error;
564                 smp_wmb();
565                 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
566                 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
567                 now = current_kernel_time();
568                 key->expiry = now.tv_sec + timeout;
569                 key_schedule_gc(key->expiry + key_gc_delay);
570 
571                 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
572                         awaken = 1;
573 
574                 ret = 0;
575 
576                 /* and link it into the destination keyring */
577                 if (keyring && link_ret == 0)
578                         __key_link(key, &edit);
579 
580                 /* disable the authorisation key */
581                 if (authkey)
582                         key_revoke(authkey);
583         }
584 
585         mutex_unlock(&key_construction_mutex);
586 
587         if (keyring && link_ret == 0)
588                 __key_link_end(keyring, &key->index_key, edit);
589 
590         /* wake up anyone waiting for a key to be constructed */
591         if (awaken)
592                 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
593 
594         return ret == 0 ? link_ret : ret;
595 }
596 EXPORT_SYMBOL(key_reject_and_link);
597 
598 /**
599  * key_put - Discard a reference to a key.
600  * @key: The key to discard a reference from.
601  *
602  * Discard a reference to a key, and when all the references are gone, we
603  * schedule the cleanup task to come and pull it out of the tree in process
604  * context at some later time.
605  */
606 void key_put(struct key *key)
607 {
608         if (key) {
609                 key_check(key);
610 
611                 if (atomic_dec_and_test(&key->usage))
612                         schedule_work(&key_gc_work);
613         }
614 }
615 EXPORT_SYMBOL(key_put);
616 
617 /*
618  * Find a key by its serial number.
619  */
620 struct key *key_lookup(key_serial_t id)
621 {
622         struct rb_node *n;
623         struct key *key;
624 
625         spin_lock(&key_serial_lock);
626 
627         /* search the tree for the specified key */
628         n = key_serial_tree.rb_node;
629         while (n) {
630                 key = rb_entry(n, struct key, serial_node);
631 
632                 if (id < key->serial)
633                         n = n->rb_left;
634                 else if (id > key->serial)
635                         n = n->rb_right;
636                 else
637                         goto found;
638         }
639 
640 not_found:
641         key = ERR_PTR(-ENOKEY);
642         goto error;
643 
644 found:
645         /* pretend it doesn't exist if it is awaiting deletion */
646         if (atomic_read(&key->usage) == 0)
647                 goto not_found;
648 
649         /* this races with key_put(), but that doesn't matter since key_put()
650          * doesn't actually change the key
651          */
652         __key_get(key);
653 
654 error:
655         spin_unlock(&key_serial_lock);
656         return key;
657 }
658 
659 /*
660  * Find and lock the specified key type against removal.
661  *
662  * We return with the sem read-locked if successful.  If the type wasn't
663  * available -ENOKEY is returned instead.
664  */
665 struct key_type *key_type_lookup(const char *type)
666 {
667         struct key_type *ktype;
668 
669         down_read(&key_types_sem);
670 
671         /* look up the key type to see if it's one of the registered kernel
672          * types */
673         list_for_each_entry(ktype, &key_types_list, link) {
674                 if (strcmp(ktype->name, type) == 0)
675                         goto found_kernel_type;
676         }
677 
678         up_read(&key_types_sem);
679         ktype = ERR_PTR(-ENOKEY);
680 
681 found_kernel_type:
682         return ktype;
683 }
684 
685 void key_set_timeout(struct key *key, unsigned timeout)
686 {
687         struct timespec now;
688         time_t expiry = 0;
689 
690         /* make the changes with the locks held to prevent races */
691         down_write(&key->sem);
692 
693         if (timeout > 0) {
694                 now = current_kernel_time();
695                 expiry = now.tv_sec + timeout;
696         }
697 
698         key->expiry = expiry;
699         key_schedule_gc(key->expiry + key_gc_delay);
700 
701         up_write(&key->sem);
702 }
703 EXPORT_SYMBOL_GPL(key_set_timeout);
704 
705 /*
706  * Unlock a key type locked by key_type_lookup().
707  */
708 void key_type_put(struct key_type *ktype)
709 {
710         up_read(&key_types_sem);
711 }
712 
713 /*
714  * Attempt to update an existing key.
715  *
716  * The key is given to us with an incremented refcount that we need to discard
717  * if we get an error.
718  */
719 static inline key_ref_t __key_update(key_ref_t key_ref,
720                                      struct key_preparsed_payload *prep)
721 {
722         struct key *key = key_ref_to_ptr(key_ref);
723         int ret;
724 
725         /* need write permission on the key to update it */
726         ret = key_permission(key_ref, KEY_NEED_WRITE);
727         if (ret < 0)
728                 goto error;
729 
730         ret = -EEXIST;
731         if (!key->type->update)
732                 goto error;
733 
734         down_write(&key->sem);
735 
736         ret = key->type->update(key, prep);
737         if (ret == 0)
738                 /* updating a negative key instantiates it */
739                 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
740 
741         up_write(&key->sem);
742 
743         if (ret < 0)
744                 goto error;
745 out:
746         return key_ref;
747 
748 error:
749         key_put(key);
750         key_ref = ERR_PTR(ret);
751         goto out;
752 }
753 
754 /**
755  * key_create_or_update - Update or create and instantiate a key.
756  * @keyring_ref: A pointer to the destination keyring with possession flag.
757  * @type: The type of key.
758  * @description: The searchable description for the key.
759  * @payload: The data to use to instantiate or update the key.
760  * @plen: The length of @payload.
761  * @perm: The permissions mask for a new key.
762  * @flags: The quota flags for a new key.
763  *
764  * Search the destination keyring for a key of the same description and if one
765  * is found, update it, otherwise create and instantiate a new one and create a
766  * link to it from that keyring.
767  *
768  * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
769  * concocted.
770  *
771  * Returns a pointer to the new key if successful, -ENODEV if the key type
772  * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
773  * caller isn't permitted to modify the keyring or the LSM did not permit
774  * creation of the key.
775  *
776  * On success, the possession flag from the keyring ref will be tacked on to
777  * the key ref before it is returned.
778  */
779 key_ref_t key_create_or_update(key_ref_t keyring_ref,
780                                const char *type,
781                                const char *description,
782                                const void *payload,
783                                size_t plen,
784                                key_perm_t perm,
785                                unsigned long flags)
786 {
787         struct keyring_index_key index_key = {
788                 .description    = description,
789         };
790         struct key_preparsed_payload prep;
791         struct assoc_array_edit *edit;
792         const struct cred *cred = current_cred();
793         struct key *keyring, *key = NULL;
794         key_ref_t key_ref;
795         int ret;
796 
797         /* look up the key type to see if it's one of the registered kernel
798          * types */
799         index_key.type = key_type_lookup(type);
800         if (IS_ERR(index_key.type)) {
801                 key_ref = ERR_PTR(-ENODEV);
802                 goto error;
803         }
804 
805         key_ref = ERR_PTR(-EINVAL);
806         if (!index_key.type->instantiate ||
807             (!index_key.description && !index_key.type->preparse))
808                 goto error_put_type;
809 
810         keyring = key_ref_to_ptr(keyring_ref);
811 
812         key_check(keyring);
813 
814         key_ref = ERR_PTR(-ENOTDIR);
815         if (keyring->type != &key_type_keyring)
816                 goto error_put_type;
817 
818         memset(&prep, 0, sizeof(prep));
819         prep.data = payload;
820         prep.datalen = plen;
821         prep.quotalen = index_key.type->def_datalen;
822         prep.trusted = flags & KEY_ALLOC_TRUSTED;
823         prep.expiry = TIME_T_MAX;
824         if (index_key.type->preparse) {
825                 ret = index_key.type->preparse(&prep);
826                 if (ret < 0) {
827                         key_ref = ERR_PTR(ret);
828                         goto error_free_prep;
829                 }
830                 if (!index_key.description)
831                         index_key.description = prep.description;
832                 key_ref = ERR_PTR(-EINVAL);
833                 if (!index_key.description)
834                         goto error_free_prep;
835         }
836         index_key.desc_len = strlen(index_key.description);
837 
838         key_ref = ERR_PTR(-EPERM);
839         if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags))
840                 goto error_free_prep;
841         flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0;
842 
843         ret = __key_link_begin(keyring, &index_key, &edit);
844         if (ret < 0) {
845                 key_ref = ERR_PTR(ret);
846                 goto error_free_prep;
847         }
848 
849         /* if we're going to allocate a new key, we're going to have
850          * to modify the keyring */
851         ret = key_permission(keyring_ref, KEY_NEED_WRITE);
852         if (ret < 0) {
853                 key_ref = ERR_PTR(ret);
854                 goto error_link_end;
855         }
856 
857         /* if it's possible to update this type of key, search for an existing
858          * key of the same type and description in the destination keyring and
859          * update that instead if possible
860          */
861         if (index_key.type->update) {
862                 key_ref = find_key_to_update(keyring_ref, &index_key);
863                 if (key_ref)
864                         goto found_matching_key;
865         }
866 
867         /* if the client doesn't provide, decide on the permissions we want */
868         if (perm == KEY_PERM_UNDEF) {
869                 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
870                 perm |= KEY_USR_VIEW;
871 
872                 if (index_key.type->read)
873                         perm |= KEY_POS_READ;
874 
875                 if (index_key.type == &key_type_keyring ||
876                     index_key.type->update)
877                         perm |= KEY_POS_WRITE;
878         }
879 
880         /* allocate a new key */
881         key = key_alloc(index_key.type, index_key.description,
882                         cred->fsuid, cred->fsgid, cred, perm, flags);
883         if (IS_ERR(key)) {
884                 key_ref = ERR_CAST(key);
885                 goto error_link_end;
886         }
887 
888         /* instantiate it and link it into the target keyring */
889         ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
890         if (ret < 0) {
891                 key_put(key);
892                 key_ref = ERR_PTR(ret);
893                 goto error_link_end;
894         }
895 
896         key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
897 
898 error_link_end:
899         __key_link_end(keyring, &index_key, edit);
900 error_free_prep:
901         if (index_key.type->preparse)
902                 index_key.type->free_preparse(&prep);
903 error_put_type:
904         key_type_put(index_key.type);
905 error:
906         return key_ref;
907 
908  found_matching_key:
909         /* we found a matching key, so we're going to try to update it
910          * - we can drop the locks first as we have the key pinned
911          */
912         __key_link_end(keyring, &index_key, edit);
913 
914         key_ref = __key_update(key_ref, &prep);
915         goto error_free_prep;
916 }
917 EXPORT_SYMBOL(key_create_or_update);
918 
919 /**
920  * key_update - Update a key's contents.
921  * @key_ref: The pointer (plus possession flag) to the key.
922  * @payload: The data to be used to update the key.
923  * @plen: The length of @payload.
924  *
925  * Attempt to update the contents of a key with the given payload data.  The
926  * caller must be granted Write permission on the key.  Negative keys can be
927  * instantiated by this method.
928  *
929  * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
930  * type does not support updating.  The key type may return other errors.
931  */
932 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
933 {
934         struct key_preparsed_payload prep;
935         struct key *key = key_ref_to_ptr(key_ref);
936         int ret;
937 
938         key_check(key);
939 
940         /* the key must be writable */
941         ret = key_permission(key_ref, KEY_NEED_WRITE);
942         if (ret < 0)
943                 goto error;
944 
945         /* attempt to update it if supported */
946         ret = -EOPNOTSUPP;
947         if (!key->type->update)
948                 goto error;
949 
950         memset(&prep, 0, sizeof(prep));
951         prep.data = payload;
952         prep.datalen = plen;
953         prep.quotalen = key->type->def_datalen;
954         prep.expiry = TIME_T_MAX;
955         if (key->type->preparse) {
956                 ret = key->type->preparse(&prep);
957                 if (ret < 0)
958                         goto error;
959         }
960 
961         down_write(&key->sem);
962 
963         ret = key->type->update(key, &prep);
964         if (ret == 0)
965                 /* updating a negative key instantiates it */
966                 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
967 
968         up_write(&key->sem);
969 
970 error:
971         if (key->type->preparse)
972                 key->type->free_preparse(&prep);
973         return ret;
974 }
975 EXPORT_SYMBOL(key_update);
976 
977 /**
978  * key_revoke - Revoke a key.
979  * @key: The key to be revoked.
980  *
981  * Mark a key as being revoked and ask the type to free up its resources.  The
982  * revocation timeout is set and the key and all its links will be
983  * automatically garbage collected after key_gc_delay amount of time if they
984  * are not manually dealt with first.
985  */
986 void key_revoke(struct key *key)
987 {
988         struct timespec now;
989         time_t time;
990 
991         key_check(key);
992 
993         /* make sure no one's trying to change or use the key when we mark it
994          * - we tell lockdep that we might nest because we might be revoking an
995          *   authorisation key whilst holding the sem on a key we've just
996          *   instantiated
997          */
998         down_write_nested(&key->sem, 1);
999         if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
1000             key->type->revoke)
1001                 key->type->revoke(key);
1002 
1003         /* set the death time to no more than the expiry time */
1004         now = current_kernel_time();
1005         time = now.tv_sec;
1006         if (key->revoked_at == 0 || key->revoked_at > time) {
1007                 key->revoked_at = time;
1008                 key_schedule_gc(key->revoked_at + key_gc_delay);
1009         }
1010 
1011         up_write(&key->sem);
1012 }
1013 EXPORT_SYMBOL(key_revoke);
1014 
1015 /**
1016  * key_invalidate - Invalidate a key.
1017  * @key: The key to be invalidated.
1018  *
1019  * Mark a key as being invalidated and have it cleaned up immediately.  The key
1020  * is ignored by all searches and other operations from this point.
1021  */
1022 void key_invalidate(struct key *key)
1023 {
1024         kenter("%d", key_serial(key));
1025 
1026         key_check(key);
1027 
1028         if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1029                 down_write_nested(&key->sem, 1);
1030                 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1031                         key_schedule_gc_links();
1032                 up_write(&key->sem);
1033         }
1034 }
1035 EXPORT_SYMBOL(key_invalidate);
1036 
1037 /**
1038  * generic_key_instantiate - Simple instantiation of a key from preparsed data
1039  * @key: The key to be instantiated
1040  * @prep: The preparsed data to load.
1041  *
1042  * Instantiate a key from preparsed data.  We assume we can just copy the data
1043  * in directly and clear the old pointers.
1044  *
1045  * This can be pointed to directly by the key type instantiate op pointer.
1046  */
1047 int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1048 {
1049         int ret;
1050 
1051         pr_devel("==>%s()\n", __func__);
1052 
1053         ret = key_payload_reserve(key, prep->quotalen);
1054         if (ret == 0) {
1055                 rcu_assign_keypointer(key, prep->payload.data[0]);
1056                 key->payload.data[1] = prep->payload.data[1];
1057                 key->payload.data[2] = prep->payload.data[2];
1058                 key->payload.data[3] = prep->payload.data[3];
1059                 prep->payload.data[0] = NULL;
1060                 prep->payload.data[1] = NULL;
1061                 prep->payload.data[2] = NULL;
1062                 prep->payload.data[3] = NULL;
1063         }
1064         pr_devel("<==%s() = %d\n", __func__, ret);
1065         return ret;
1066 }
1067 EXPORT_SYMBOL(generic_key_instantiate);
1068 
1069 /**
1070  * register_key_type - Register a type of key.
1071  * @ktype: The new key type.
1072  *
1073  * Register a new key type.
1074  *
1075  * Returns 0 on success or -EEXIST if a type of this name already exists.
1076  */
1077 int register_key_type(struct key_type *ktype)
1078 {
1079         struct key_type *p;
1080         int ret;
1081 
1082         memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1083 
1084         ret = -EEXIST;
1085         down_write(&key_types_sem);
1086 
1087         /* disallow key types with the same name */
1088         list_for_each_entry(p, &key_types_list, link) {
1089                 if (strcmp(p->name, ktype->name) == 0)
1090                         goto out;
1091         }
1092 
1093         /* store the type */
1094         list_add(&ktype->link, &key_types_list);
1095 
1096         pr_notice("Key type %s registered\n", ktype->name);
1097         ret = 0;
1098 
1099 out:
1100         up_write(&key_types_sem);
1101         return ret;
1102 }
1103 EXPORT_SYMBOL(register_key_type);
1104 
1105 /**
1106  * unregister_key_type - Unregister a type of key.
1107  * @ktype: The key type.
1108  *
1109  * Unregister a key type and mark all the extant keys of this type as dead.
1110  * Those keys of this type are then destroyed to get rid of their payloads and
1111  * they and their links will be garbage collected as soon as possible.
1112  */
1113 void unregister_key_type(struct key_type *ktype)
1114 {
1115         down_write(&key_types_sem);
1116         list_del_init(&ktype->link);
1117         downgrade_write(&key_types_sem);
1118         key_gc_keytype(ktype);
1119         pr_notice("Key type %s unregistered\n", ktype->name);
1120         up_read(&key_types_sem);
1121 }
1122 EXPORT_SYMBOL(unregister_key_type);
1123 
1124 /*
1125  * Initialise the key management state.
1126  */
1127 void __init key_init(void)
1128 {
1129         /* allocate a slab in which we can store keys */
1130         key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1131                         0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1132 
1133         /* add the special key types */
1134         list_add_tail(&key_type_keyring.link, &key_types_list);
1135         list_add_tail(&key_type_dead.link, &key_types_list);
1136         list_add_tail(&key_type_user.link, &key_types_list);
1137         list_add_tail(&key_type_logon.link, &key_types_list);
1138 
1139         /* record the root user tracking */
1140         rb_link_node(&root_key_user.node,
1141                      NULL,
1142                      &key_user_tree.rb_node);
1143 
1144         rb_insert_color(&root_key_user.node,
1145                         &key_user_tree);
1146 }
1147 

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