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1/* Manage a process's keyrings
2 *
3 * Copyright (C) 2004-2005, 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/sched.h>
15#include <linux/keyctl.h>
16#include <linux/fs.h>
17#include <linux/err.h>
18#include <linux/mutex.h>
19#include <linux/security.h>
20#include <linux/user_namespace.h>
21#include <asm/uaccess.h>
22#include "internal.h"
23
24/* Session keyring create vs join semaphore */
25static DEFINE_MUTEX(key_session_mutex);
26
27/* User keyring creation semaphore */
28static DEFINE_MUTEX(key_user_keyring_mutex);
29
30/* The root user's tracking struct */
31struct key_user root_key_user = {
32 .usage = ATOMIC_INIT(3),
33 .cons_lock = __MUTEX_INITIALIZER(root_key_user.cons_lock),
34 .lock = __SPIN_LOCK_UNLOCKED(root_key_user.lock),
35 .nkeys = ATOMIC_INIT(2),
36 .nikeys = ATOMIC_INIT(2),
37 .uid = 0,
38 .user_ns = &init_user_ns,
39};
40
41/*
42 * Install the user and user session keyrings for the current process's UID.
43 */
44int install_user_keyrings(void)
45{
46 struct user_struct *user;
47 const struct cred *cred;
48 struct key *uid_keyring, *session_keyring;
49 char buf[20];
50 int ret;
51
52 cred = current_cred();
53 user = cred->user;
54
55 kenter("%p{%u}", user, user->uid);
56
57 if (user->uid_keyring) {
58 kleave(" = 0 [exist]");
59 return 0;
60 }
61
62 mutex_lock(&key_user_keyring_mutex);
63 ret = 0;
64
65 if (!user->uid_keyring) {
66 /* get the UID-specific keyring
67 * - there may be one in existence already as it may have been
68 * pinned by a session, but the user_struct pointing to it
69 * may have been destroyed by setuid */
70 sprintf(buf, "_uid.%u", user->uid);
71
72 uid_keyring = find_keyring_by_name(buf, true);
73 if (IS_ERR(uid_keyring)) {
74 uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1,
75 cred, KEY_ALLOC_IN_QUOTA,
76 NULL);
77 if (IS_ERR(uid_keyring)) {
78 ret = PTR_ERR(uid_keyring);
79 goto error;
80 }
81 }
82
83 /* get a default session keyring (which might also exist
84 * already) */
85 sprintf(buf, "_uid_ses.%u", user->uid);
86
87 session_keyring = find_keyring_by_name(buf, true);
88 if (IS_ERR(session_keyring)) {
89 session_keyring =
90 keyring_alloc(buf, user->uid, (gid_t) -1,
91 cred, KEY_ALLOC_IN_QUOTA, NULL);
92 if (IS_ERR(session_keyring)) {
93 ret = PTR_ERR(session_keyring);
94 goto error_release;
95 }
96
97 /* we install a link from the user session keyring to
98 * the user keyring */
99 ret = key_link(session_keyring, uid_keyring);
100 if (ret < 0)
101 goto error_release_both;
102 }
103
104 /* install the keyrings */
105 user->uid_keyring = uid_keyring;
106 user->session_keyring = session_keyring;
107 }
108
109 mutex_unlock(&key_user_keyring_mutex);
110 kleave(" = 0");
111 return 0;
112
113error_release_both:
114 key_put(session_keyring);
115error_release:
116 key_put(uid_keyring);
117error:
118 mutex_unlock(&key_user_keyring_mutex);
119 kleave(" = %d", ret);
120 return ret;
121}
122
123/*
124 * Install a fresh thread keyring directly to new credentials. This keyring is
125 * allowed to overrun the quota.
126 */
127int install_thread_keyring_to_cred(struct cred *new)
128{
129 struct key *keyring;
130
131 keyring = keyring_alloc("_tid", new->uid, new->gid, new,
132 KEY_ALLOC_QUOTA_OVERRUN, NULL);
133 if (IS_ERR(keyring))
134 return PTR_ERR(keyring);
135
136 new->thread_keyring = keyring;
137 return 0;
138}
139
140/*
141 * Install a fresh thread keyring, discarding the old one.
142 */
143static int install_thread_keyring(void)
144{
145 struct cred *new;
146 int ret;
147
148 new = prepare_creds();
149 if (!new)
150 return -ENOMEM;
151
152 BUG_ON(new->thread_keyring);
153
154 ret = install_thread_keyring_to_cred(new);
155 if (ret < 0) {
156 abort_creds(new);
157 return ret;
158 }
159
160 return commit_creds(new);
161}
162
163/*
164 * Install a process keyring directly to a credentials struct.
165 *
166 * Returns -EEXIST if there was already a process keyring, 0 if one installed,
167 * and other value on any other error
168 */
169int install_process_keyring_to_cred(struct cred *new)
170{
171 struct key *keyring;
172 int ret;
173
174 if (new->tgcred->process_keyring)
175 return -EEXIST;
176
177 keyring = keyring_alloc("_pid", new->uid, new->gid,
178 new, KEY_ALLOC_QUOTA_OVERRUN, NULL);
179 if (IS_ERR(keyring))
180 return PTR_ERR(keyring);
181
182 spin_lock_irq(&new->tgcred->lock);
183 if (!new->tgcred->process_keyring) {
184 new->tgcred->process_keyring = keyring;
185 keyring = NULL;
186 ret = 0;
187 } else {
188 ret = -EEXIST;
189 }
190 spin_unlock_irq(&new->tgcred->lock);
191 key_put(keyring);
192 return ret;
193}
194
195/*
196 * Make sure a process keyring is installed for the current process. The
197 * existing process keyring is not replaced.
198 *
199 * Returns 0 if there is a process keyring by the end of this function, some
200 * error otherwise.
201 */
202static int install_process_keyring(void)
203{
204 struct cred *new;
205 int ret;
206
207 new = prepare_creds();
208 if (!new)
209 return -ENOMEM;
210
211 ret = install_process_keyring_to_cred(new);
212 if (ret < 0) {
213 abort_creds(new);
214 return ret != -EEXIST ? ret : 0;
215 }
216
217 return commit_creds(new);
218}
219
220/*
221 * Install a session keyring directly to a credentials struct.
222 */
223int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
224{
225 unsigned long flags;
226 struct key *old;
227
228 might_sleep();
229
230 /* create an empty session keyring */
231 if (!keyring) {
232 flags = KEY_ALLOC_QUOTA_OVERRUN;
233 if (cred->tgcred->session_keyring)
234 flags = KEY_ALLOC_IN_QUOTA;
235
236 keyring = keyring_alloc("_ses", cred->uid, cred->gid,
237 cred, flags, NULL);
238 if (IS_ERR(keyring))
239 return PTR_ERR(keyring);
240 } else {
241 atomic_inc(&keyring->usage);
242 }
243
244 /* install the keyring */
245 spin_lock_irq(&cred->tgcred->lock);
246 old = cred->tgcred->session_keyring;
247 rcu_assign_pointer(cred->tgcred->session_keyring, keyring);
248 spin_unlock_irq(&cred->tgcred->lock);
249
250 /* we're using RCU on the pointer, but there's no point synchronising
251 * on it if it didn't previously point to anything */
252 if (old) {
253 synchronize_rcu();
254 key_put(old);
255 }
256
257 return 0;
258}
259
260/*
261 * Install a session keyring, discarding the old one. If a keyring is not
262 * supplied, an empty one is invented.
263 */
264static int install_session_keyring(struct key *keyring)
265{
266 struct cred *new;
267 int ret;
268
269 new = prepare_creds();
270 if (!new)
271 return -ENOMEM;
272
273 ret = install_session_keyring_to_cred(new, NULL);
274 if (ret < 0) {
275 abort_creds(new);
276 return ret;
277 }
278
279 return commit_creds(new);
280}
281
282/*
283 * Handle the fsuid changing.
284 */
285void key_fsuid_changed(struct task_struct *tsk)
286{
287 /* update the ownership of the thread keyring */
288 BUG_ON(!tsk->cred);
289 if (tsk->cred->thread_keyring) {
290 down_write(&tsk->cred->thread_keyring->sem);
291 tsk->cred->thread_keyring->uid = tsk->cred->fsuid;
292 up_write(&tsk->cred->thread_keyring->sem);
293 }
294}
295
296/*
297 * Handle the fsgid changing.
298 */
299void key_fsgid_changed(struct task_struct *tsk)
300{
301 /* update the ownership of the thread keyring */
302 BUG_ON(!tsk->cred);
303 if (tsk->cred->thread_keyring) {
304 down_write(&tsk->cred->thread_keyring->sem);
305 tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
306 up_write(&tsk->cred->thread_keyring->sem);
307 }
308}
309
310/*
311 * Search the process keyrings attached to the supplied cred for the first
312 * matching key.
313 *
314 * The search criteria are the type and the match function. The description is
315 * given to the match function as a parameter, but doesn't otherwise influence
316 * the search. Typically the match function will compare the description
317 * parameter to the key's description.
318 *
319 * This can only search keyrings that grant Search permission to the supplied
320 * credentials. Keyrings linked to searched keyrings will also be searched if
321 * they grant Search permission too. Keys can only be found if they grant
322 * Search permission to the credentials.
323 *
324 * Returns a pointer to the key with the key usage count incremented if
325 * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
326 * matched negative keys.
327 *
328 * In the case of a successful return, the possession attribute is set on the
329 * returned key reference.
330 */
331key_ref_t search_my_process_keyrings(struct key_type *type,
332 const void *description,
333 key_match_func_t match,
334 bool no_state_check,
335 const struct cred *cred)
336{
337 key_ref_t key_ref, ret, err;
338
339 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
340 * searchable, but we failed to find a key or we found a negative key;
341 * otherwise we want to return a sample error (probably -EACCES) if
342 * none of the keyrings were searchable
343 *
344 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
345 */
346 key_ref = NULL;
347 ret = NULL;
348 err = ERR_PTR(-EAGAIN);
349
350 /* search the thread keyring first */
351 if (cred->thread_keyring) {
352 key_ref = keyring_search_aux(
353 make_key_ref(cred->thread_keyring, 1),
354 cred, type, description, match, no_state_check);
355 if (!IS_ERR(key_ref))
356 goto found;
357
358 switch (PTR_ERR(key_ref)) {
359 case -EAGAIN: /* no key */
360 if (ret)
361 break;
362 case -ENOKEY: /* negative key */
363 ret = key_ref;
364 break;
365 default:
366 err = key_ref;
367 break;
368 }
369 }
370
371 /* search the process keyring second */
372 if (cred->tgcred->process_keyring) {
373 key_ref = keyring_search_aux(
374 make_key_ref(cred->tgcred->process_keyring, 1),
375 cred, type, description, match, no_state_check);
376 if (!IS_ERR(key_ref))
377 goto found;
378
379 switch (PTR_ERR(key_ref)) {
380 case -EAGAIN: /* no key */
381 if (ret)
382 break;
383 case -ENOKEY: /* negative key */
384 ret = key_ref;
385 break;
386 default:
387 err = key_ref;
388 break;
389 }
390 }
391
392 /* search the session keyring */
393 if (cred->tgcred->session_keyring) {
394 rcu_read_lock();
395 key_ref = keyring_search_aux(
396 make_key_ref(rcu_dereference(
397 cred->tgcred->session_keyring),
398 1),
399 cred, type, description, match, no_state_check);
400 rcu_read_unlock();
401
402 if (!IS_ERR(key_ref))
403 goto found;
404
405 switch (PTR_ERR(key_ref)) {
406 case -EAGAIN: /* no key */
407 if (ret)
408 break;
409 case -ENOKEY: /* negative key */
410 ret = key_ref;
411 break;
412 default:
413 err = key_ref;
414 break;
415 }
416 }
417 /* or search the user-session keyring */
418 else if (cred->user->session_keyring) {
419 key_ref = keyring_search_aux(
420 make_key_ref(cred->user->session_keyring, 1),
421 cred, type, description, match, no_state_check);
422 if (!IS_ERR(key_ref))
423 goto found;
424
425 switch (PTR_ERR(key_ref)) {
426 case -EAGAIN: /* no key */
427 if (ret)
428 break;
429 case -ENOKEY: /* negative key */
430 ret = key_ref;
431 break;
432 default:
433 err = key_ref;
434 break;
435 }
436 }
437
438 /* no key - decide on the error we're going to go for */
439 key_ref = ret ? ret : err;
440
441found:
442 return key_ref;
443}
444
445/*
446 * Search the process keyrings attached to the supplied cred for the first
447 * matching key in the manner of search_my_process_keyrings(), but also search
448 * the keys attached to the assumed authorisation key using its credentials if
449 * one is available.
450 *
451 * Return same as search_my_process_keyrings().
452 */
453key_ref_t search_process_keyrings(struct key_type *type,
454 const void *description,
455 key_match_func_t match,
456 const struct cred *cred)
457{
458 struct request_key_auth *rka;
459 key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
460
461 might_sleep();
462
463 key_ref = search_my_process_keyrings(type, description, match,
464 false, cred);
465 if (!IS_ERR(key_ref))
466 goto found;
467 err = key_ref;
468
469 /* if this process has an instantiation authorisation key, then we also
470 * search the keyrings of the process mentioned there
471 * - we don't permit access to request_key auth keys via this method
472 */
473 if (cred->request_key_auth &&
474 cred == current_cred() &&
475 type != &key_type_request_key_auth
476 ) {
477 /* defend against the auth key being revoked */
478 down_read(&cred->request_key_auth->sem);
479
480 if (key_validate(cred->request_key_auth) == 0) {
481 rka = cred->request_key_auth->payload.data;
482
483 key_ref = search_process_keyrings(type, description,
484 match, rka->cred);
485
486 up_read(&cred->request_key_auth->sem);
487
488 if (!IS_ERR(key_ref))
489 goto found;
490
491 ret = key_ref;
492 } else {
493 up_read(&cred->request_key_auth->sem);
494 }
495 }
496
497 /* no key - decide on the error we're going to go for */
498 if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
499 key_ref = ERR_PTR(-ENOKEY);
500 else if (err == ERR_PTR(-EACCES))
501 key_ref = ret;
502 else
503 key_ref = err;
504
505found:
506 return key_ref;
507}
508
509/*
510 * See if the key we're looking at is the target key.
511 */
512int lookup_user_key_possessed(const struct key *key, const void *target)
513{
514 return key == target;
515}
516
517/*
518 * Look up a key ID given us by userspace with a given permissions mask to get
519 * the key it refers to.
520 *
521 * Flags can be passed to request that special keyrings be created if referred
522 * to directly, to permit partially constructed keys to be found and to skip
523 * validity and permission checks on the found key.
524 *
525 * Returns a pointer to the key with an incremented usage count if successful;
526 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
527 * to a key or the best found key was a negative key; -EKEYREVOKED or
528 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
529 * found key doesn't grant the requested permit or the LSM denied access to it;
530 * or -ENOMEM if a special keyring couldn't be created.
531 *
532 * In the case of a successful return, the possession attribute is set on the
533 * returned key reference.
534 */
535key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
536 key_perm_t perm)
537{
538 struct request_key_auth *rka;
539 const struct cred *cred;
540 struct key *key;
541 key_ref_t key_ref, skey_ref;
542 int ret;
543
544try_again:
545 cred = get_current_cred();
546 key_ref = ERR_PTR(-ENOKEY);
547
548 switch (id) {
549 case KEY_SPEC_THREAD_KEYRING:
550 if (!cred->thread_keyring) {
551 if (!(lflags & KEY_LOOKUP_CREATE))
552 goto error;
553
554 ret = install_thread_keyring();
555 if (ret < 0) {
556 key_ref = ERR_PTR(ret);
557 goto error;
558 }
559 goto reget_creds;
560 }
561
562 key = cred->thread_keyring;
563 atomic_inc(&key->usage);
564 key_ref = make_key_ref(key, 1);
565 break;
566
567 case KEY_SPEC_PROCESS_KEYRING:
568 if (!cred->tgcred->process_keyring) {
569 if (!(lflags & KEY_LOOKUP_CREATE))
570 goto error;
571
572 ret = install_process_keyring();
573 if (ret < 0) {
574 key_ref = ERR_PTR(ret);
575 goto error;
576 }
577 goto reget_creds;
578 }
579
580 key = cred->tgcred->process_keyring;
581 atomic_inc(&key->usage);
582 key_ref = make_key_ref(key, 1);
583 break;
584
585 case KEY_SPEC_SESSION_KEYRING:
586 if (!cred->tgcred->session_keyring) {
587 /* always install a session keyring upon access if one
588 * doesn't exist yet */
589 ret = install_user_keyrings();
590 if (ret < 0)
591 goto error;
592 ret = install_session_keyring(
593 cred->user->session_keyring);
594
595 if (ret < 0)
596 goto error;
597 goto reget_creds;
598 }
599
600 rcu_read_lock();
601 key = rcu_dereference(cred->tgcred->session_keyring);
602 atomic_inc(&key->usage);
603 rcu_read_unlock();
604 key_ref = make_key_ref(key, 1);
605 break;
606
607 case KEY_SPEC_USER_KEYRING:
608 if (!cred->user->uid_keyring) {
609 ret = install_user_keyrings();
610 if (ret < 0)
611 goto error;
612 }
613
614 key = cred->user->uid_keyring;
615 atomic_inc(&key->usage);
616 key_ref = make_key_ref(key, 1);
617 break;
618
619 case KEY_SPEC_USER_SESSION_KEYRING:
620 if (!cred->user->session_keyring) {
621 ret = install_user_keyrings();
622 if (ret < 0)
623 goto error;
624 }
625
626 key = cred->user->session_keyring;
627 atomic_inc(&key->usage);
628 key_ref = make_key_ref(key, 1);
629 break;
630
631 case KEY_SPEC_GROUP_KEYRING:
632 /* group keyrings are not yet supported */
633 key_ref = ERR_PTR(-EINVAL);
634 goto error;
635
636 case KEY_SPEC_REQKEY_AUTH_KEY:
637 key = cred->request_key_auth;
638 if (!key)
639 goto error;
640
641 atomic_inc(&key->usage);
642 key_ref = make_key_ref(key, 1);
643 break;
644
645 case KEY_SPEC_REQUESTOR_KEYRING:
646 if (!cred->request_key_auth)
647 goto error;
648
649 down_read(&cred->request_key_auth->sem);
650 if (cred->request_key_auth->flags & KEY_FLAG_REVOKED) {
651 key_ref = ERR_PTR(-EKEYREVOKED);
652 key = NULL;
653 } else {
654 rka = cred->request_key_auth->payload.data;
655 key = rka->dest_keyring;
656 atomic_inc(&key->usage);
657 }
658 up_read(&cred->request_key_auth->sem);
659 if (!key)
660 goto error;
661 key_ref = make_key_ref(key, 1);
662 break;
663
664 default:
665 key_ref = ERR_PTR(-EINVAL);
666 if (id < 1)
667 goto error;
668
669 key = key_lookup(id);
670 if (IS_ERR(key)) {
671 key_ref = ERR_CAST(key);
672 goto error;
673 }
674
675 key_ref = make_key_ref(key, 0);
676
677 /* check to see if we possess the key */
678 skey_ref = search_process_keyrings(key->type, key,
679 lookup_user_key_possessed,
680 cred);
681
682 if (!IS_ERR(skey_ref)) {
683 key_put(key);
684 key_ref = skey_ref;
685 }
686
687 break;
688 }
689
690 /* unlink does not use the nominated key in any way, so can skip all
691 * the permission checks as it is only concerned with the keyring */
692 if (lflags & KEY_LOOKUP_FOR_UNLINK) {
693 ret = 0;
694 goto error;
695 }
696
697 if (!(lflags & KEY_LOOKUP_PARTIAL)) {
698 ret = wait_for_key_construction(key, true);
699 switch (ret) {
700 case -ERESTARTSYS:
701 goto invalid_key;
702 default:
703 if (perm)
704 goto invalid_key;
705 case 0:
706 break;
707 }
708 } else if (perm) {
709 ret = key_validate(key);
710 if (ret < 0)
711 goto invalid_key;
712 }
713
714 ret = -EIO;
715 if (!(lflags & KEY_LOOKUP_PARTIAL) &&
716 !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
717 goto invalid_key;
718
719 /* check the permissions */
720 ret = key_task_permission(key_ref, cred, perm);
721 if (ret < 0)
722 goto invalid_key;
723
724error:
725 put_cred(cred);
726 return key_ref;
727
728invalid_key:
729 key_ref_put(key_ref);
730 key_ref = ERR_PTR(ret);
731 goto error;
732
733 /* if we attempted to install a keyring, then it may have caused new
734 * creds to be installed */
735reget_creds:
736 put_cred(cred);
737 goto try_again;
738}
739
740/*
741 * Join the named keyring as the session keyring if possible else attempt to
742 * create a new one of that name and join that.
743 *
744 * If the name is NULL, an empty anonymous keyring will be installed as the
745 * session keyring.
746 *
747 * Named session keyrings are joined with a semaphore held to prevent the
748 * keyrings from going away whilst the attempt is made to going them and also
749 * to prevent a race in creating compatible session keyrings.
750 */
751long join_session_keyring(const char *name)
752{
753 const struct cred *old;
754 struct cred *new;
755 struct key *keyring;
756 long ret, serial;
757
758 /* only permit this if there's a single thread in the thread group -
759 * this avoids us having to adjust the creds on all threads and risking
760 * ENOMEM */
761 if (!current_is_single_threaded())
762 return -EMLINK;
763
764 new = prepare_creds();
765 if (!new)
766 return -ENOMEM;
767 old = current_cred();
768
769 /* if no name is provided, install an anonymous keyring */
770 if (!name) {
771 ret = install_session_keyring_to_cred(new, NULL);
772 if (ret < 0)
773 goto error;
774
775 serial = new->tgcred->session_keyring->serial;
776 ret = commit_creds(new);
777 if (ret == 0)
778 ret = serial;
779 goto okay;
780 }
781
782 /* allow the user to join or create a named keyring */
783 mutex_lock(&key_session_mutex);
784
785 /* look for an existing keyring of this name */
786 keyring = find_keyring_by_name(name, false);
787 if (PTR_ERR(keyring) == -ENOKEY) {
788 /* not found - try and create a new one */
789 keyring = keyring_alloc(name, old->uid, old->gid, old,
790 KEY_ALLOC_IN_QUOTA, NULL);
791 if (IS_ERR(keyring)) {
792 ret = PTR_ERR(keyring);
793 goto error2;
794 }
795 } else if (IS_ERR(keyring)) {
796 ret = PTR_ERR(keyring);
797 goto error2;
798 }
799
800 /* we've got a keyring - now to install it */
801 ret = install_session_keyring_to_cred(new, keyring);
802 if (ret < 0)
803 goto error2;
804
805 commit_creds(new);
806 mutex_unlock(&key_session_mutex);
807
808 ret = keyring->serial;
809 key_put(keyring);
810okay:
811 return ret;
812
813error2:
814 mutex_unlock(&key_session_mutex);
815error:
816 abort_creds(new);
817 return ret;
818}
819
820/*
821 * Replace a process's session keyring on behalf of one of its children when
822 * the target process is about to resume userspace execution.
823 */
824void key_replace_session_keyring(void)
825{
826 const struct cred *old;
827 struct cred *new;
828
829 if (!current->replacement_session_keyring)
830 return;
831
832 write_lock_irq(&tasklist_lock);
833 new = current->replacement_session_keyring;
834 current->replacement_session_keyring = NULL;
835 write_unlock_irq(&tasklist_lock);
836
837 if (!new)
838 return;
839
840 old = current_cred();
841 new-> uid = old-> uid;
842 new-> euid = old-> euid;
843 new-> suid = old-> suid;
844 new->fsuid = old->fsuid;
845 new-> gid = old-> gid;
846 new-> egid = old-> egid;
847 new-> sgid = old-> sgid;
848 new->fsgid = old->fsgid;
849 new->user = get_uid(old->user);
850 new->user_ns = new->user->user_ns;
851 new->group_info = get_group_info(old->group_info);
852
853 new->securebits = old->securebits;
854 new->cap_inheritable = old->cap_inheritable;
855 new->cap_permitted = old->cap_permitted;
856 new->cap_effective = old->cap_effective;
857 new->cap_bset = old->cap_bset;
858
859 new->jit_keyring = old->jit_keyring;
860 new->thread_keyring = key_get(old->thread_keyring);
861 new->tgcred->tgid = old->tgcred->tgid;
862 new->tgcred->process_keyring = key_get(old->tgcred->process_keyring);
863
864 security_transfer_creds(new, old);
865
866 commit_creds(new);
867}
1/* Manage a process's keyrings
2 *
3 * Copyright (C) 2004-2005, 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/sched.h>
15#include <linux/keyctl.h>
16#include <linux/fs.h>
17#include <linux/err.h>
18#include <linux/mutex.h>
19#include <linux/security.h>
20#include <linux/user_namespace.h>
21#include <asm/uaccess.h>
22#include "internal.h"
23
24/* Session keyring create vs join semaphore */
25static DEFINE_MUTEX(key_session_mutex);
26
27/* User keyring creation semaphore */
28static DEFINE_MUTEX(key_user_keyring_mutex);
29
30/* The root user's tracking struct */
31struct key_user root_key_user = {
32 .usage = ATOMIC_INIT(3),
33 .cons_lock = __MUTEX_INITIALIZER(root_key_user.cons_lock),
34 .lock = __SPIN_LOCK_UNLOCKED(root_key_user.lock),
35 .nkeys = ATOMIC_INIT(2),
36 .nikeys = ATOMIC_INIT(2),
37 .uid = 0,
38 .user_ns = &init_user_ns,
39};
40
41/*
42 * Install the user and user session keyrings for the current process's UID.
43 */
44int install_user_keyrings(void)
45{
46 struct user_struct *user;
47 const struct cred *cred;
48 struct key *uid_keyring, *session_keyring;
49 char buf[20];
50 int ret;
51
52 cred = current_cred();
53 user = cred->user;
54
55 kenter("%p{%u}", user, user->uid);
56
57 if (user->uid_keyring) {
58 kleave(" = 0 [exist]");
59 return 0;
60 }
61
62 mutex_lock(&key_user_keyring_mutex);
63 ret = 0;
64
65 if (!user->uid_keyring) {
66 /* get the UID-specific keyring
67 * - there may be one in existence already as it may have been
68 * pinned by a session, but the user_struct pointing to it
69 * may have been destroyed by setuid */
70 sprintf(buf, "_uid.%u", user->uid);
71
72 uid_keyring = find_keyring_by_name(buf, true);
73 if (IS_ERR(uid_keyring)) {
74 uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1,
75 cred, KEY_ALLOC_IN_QUOTA,
76 NULL);
77 if (IS_ERR(uid_keyring)) {
78 ret = PTR_ERR(uid_keyring);
79 goto error;
80 }
81 }
82
83 /* get a default session keyring (which might also exist
84 * already) */
85 sprintf(buf, "_uid_ses.%u", user->uid);
86
87 session_keyring = find_keyring_by_name(buf, true);
88 if (IS_ERR(session_keyring)) {
89 session_keyring =
90 keyring_alloc(buf, user->uid, (gid_t) -1,
91 cred, KEY_ALLOC_IN_QUOTA, NULL);
92 if (IS_ERR(session_keyring)) {
93 ret = PTR_ERR(session_keyring);
94 goto error_release;
95 }
96
97 /* we install a link from the user session keyring to
98 * the user keyring */
99 ret = key_link(session_keyring, uid_keyring);
100 if (ret < 0)
101 goto error_release_both;
102 }
103
104 /* install the keyrings */
105 user->uid_keyring = uid_keyring;
106 user->session_keyring = session_keyring;
107 }
108
109 mutex_unlock(&key_user_keyring_mutex);
110 kleave(" = 0");
111 return 0;
112
113error_release_both:
114 key_put(session_keyring);
115error_release:
116 key_put(uid_keyring);
117error:
118 mutex_unlock(&key_user_keyring_mutex);
119 kleave(" = %d", ret);
120 return ret;
121}
122
123/*
124 * Install a fresh thread keyring directly to new credentials. This keyring is
125 * allowed to overrun the quota.
126 */
127int install_thread_keyring_to_cred(struct cred *new)
128{
129 struct key *keyring;
130
131 keyring = keyring_alloc("_tid", new->uid, new->gid, new,
132 KEY_ALLOC_QUOTA_OVERRUN, NULL);
133 if (IS_ERR(keyring))
134 return PTR_ERR(keyring);
135
136 new->thread_keyring = keyring;
137 return 0;
138}
139
140/*
141 * Install a fresh thread keyring, discarding the old one.
142 */
143static int install_thread_keyring(void)
144{
145 struct cred *new;
146 int ret;
147
148 new = prepare_creds();
149 if (!new)
150 return -ENOMEM;
151
152 BUG_ON(new->thread_keyring);
153
154 ret = install_thread_keyring_to_cred(new);
155 if (ret < 0) {
156 abort_creds(new);
157 return ret;
158 }
159
160 return commit_creds(new);
161}
162
163/*
164 * Install a process keyring directly to a credentials struct.
165 *
166 * Returns -EEXIST if there was already a process keyring, 0 if one installed,
167 * and other value on any other error
168 */
169int install_process_keyring_to_cred(struct cred *new)
170{
171 struct key *keyring;
172 int ret;
173
174 if (new->tgcred->process_keyring)
175 return -EEXIST;
176
177 keyring = keyring_alloc("_pid", new->uid, new->gid,
178 new, KEY_ALLOC_QUOTA_OVERRUN, NULL);
179 if (IS_ERR(keyring))
180 return PTR_ERR(keyring);
181
182 spin_lock_irq(&new->tgcred->lock);
183 if (!new->tgcred->process_keyring) {
184 new->tgcred->process_keyring = keyring;
185 keyring = NULL;
186 ret = 0;
187 } else {
188 ret = -EEXIST;
189 }
190 spin_unlock_irq(&new->tgcred->lock);
191 key_put(keyring);
192 return ret;
193}
194
195/*
196 * Make sure a process keyring is installed for the current process. The
197 * existing process keyring is not replaced.
198 *
199 * Returns 0 if there is a process keyring by the end of this function, some
200 * error otherwise.
201 */
202static int install_process_keyring(void)
203{
204 struct cred *new;
205 int ret;
206
207 new = prepare_creds();
208 if (!new)
209 return -ENOMEM;
210
211 ret = install_process_keyring_to_cred(new);
212 if (ret < 0) {
213 abort_creds(new);
214 return ret != -EEXIST ? ret : 0;
215 }
216
217 return commit_creds(new);
218}
219
220/*
221 * Install a session keyring directly to a credentials struct.
222 */
223int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
224{
225 unsigned long flags;
226 struct key *old;
227
228 might_sleep();
229
230 /* create an empty session keyring */
231 if (!keyring) {
232 flags = KEY_ALLOC_QUOTA_OVERRUN;
233 if (cred->tgcred->session_keyring)
234 flags = KEY_ALLOC_IN_QUOTA;
235
236 keyring = keyring_alloc("_ses", cred->uid, cred->gid,
237 cred, flags, NULL);
238 if (IS_ERR(keyring))
239 return PTR_ERR(keyring);
240 } else {
241 atomic_inc(&keyring->usage);
242 }
243
244 /* install the keyring */
245 spin_lock_irq(&cred->tgcred->lock);
246 old = cred->tgcred->session_keyring;
247 rcu_assign_pointer(cred->tgcred->session_keyring, keyring);
248 spin_unlock_irq(&cred->tgcred->lock);
249
250 /* we're using RCU on the pointer, but there's no point synchronising
251 * on it if it didn't previously point to anything */
252 if (old) {
253 synchronize_rcu();
254 key_put(old);
255 }
256
257 return 0;
258}
259
260/*
261 * Install a session keyring, discarding the old one. If a keyring is not
262 * supplied, an empty one is invented.
263 */
264static int install_session_keyring(struct key *keyring)
265{
266 struct cred *new;
267 int ret;
268
269 new = prepare_creds();
270 if (!new)
271 return -ENOMEM;
272
273 ret = install_session_keyring_to_cred(new, keyring);
274 if (ret < 0) {
275 abort_creds(new);
276 return ret;
277 }
278
279 return commit_creds(new);
280}
281
282/*
283 * Handle the fsuid changing.
284 */
285void key_fsuid_changed(struct task_struct *tsk)
286{
287 /* update the ownership of the thread keyring */
288 BUG_ON(!tsk->cred);
289 if (tsk->cred->thread_keyring) {
290 down_write(&tsk->cred->thread_keyring->sem);
291 tsk->cred->thread_keyring->uid = tsk->cred->fsuid;
292 up_write(&tsk->cred->thread_keyring->sem);
293 }
294}
295
296/*
297 * Handle the fsgid changing.
298 */
299void key_fsgid_changed(struct task_struct *tsk)
300{
301 /* update the ownership of the thread keyring */
302 BUG_ON(!tsk->cred);
303 if (tsk->cred->thread_keyring) {
304 down_write(&tsk->cred->thread_keyring->sem);
305 tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
306 up_write(&tsk->cred->thread_keyring->sem);
307 }
308}
309
310/*
311 * Search the process keyrings attached to the supplied cred for the first
312 * matching key.
313 *
314 * The search criteria are the type and the match function. The description is
315 * given to the match function as a parameter, but doesn't otherwise influence
316 * the search. Typically the match function will compare the description
317 * parameter to the key's description.
318 *
319 * This can only search keyrings that grant Search permission to the supplied
320 * credentials. Keyrings linked to searched keyrings will also be searched if
321 * they grant Search permission too. Keys can only be found if they grant
322 * Search permission to the credentials.
323 *
324 * Returns a pointer to the key with the key usage count incremented if
325 * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
326 * matched negative keys.
327 *
328 * In the case of a successful return, the possession attribute is set on the
329 * returned key reference.
330 */
331key_ref_t search_my_process_keyrings(struct key_type *type,
332 const void *description,
333 key_match_func_t match,
334 bool no_state_check,
335 const struct cred *cred)
336{
337 key_ref_t key_ref, ret, err;
338
339 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
340 * searchable, but we failed to find a key or we found a negative key;
341 * otherwise we want to return a sample error (probably -EACCES) if
342 * none of the keyrings were searchable
343 *
344 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
345 */
346 key_ref = NULL;
347 ret = NULL;
348 err = ERR_PTR(-EAGAIN);
349
350 /* search the thread keyring first */
351 if (cred->thread_keyring) {
352 key_ref = keyring_search_aux(
353 make_key_ref(cred->thread_keyring, 1),
354 cred, type, description, match, no_state_check);
355 if (!IS_ERR(key_ref))
356 goto found;
357
358 switch (PTR_ERR(key_ref)) {
359 case -EAGAIN: /* no key */
360 if (ret)
361 break;
362 case -ENOKEY: /* negative key */
363 ret = key_ref;
364 break;
365 default:
366 err = key_ref;
367 break;
368 }
369 }
370
371 /* search the process keyring second */
372 if (cred->tgcred->process_keyring) {
373 key_ref = keyring_search_aux(
374 make_key_ref(cred->tgcred->process_keyring, 1),
375 cred, type, description, match, no_state_check);
376 if (!IS_ERR(key_ref))
377 goto found;
378
379 switch (PTR_ERR(key_ref)) {
380 case -EAGAIN: /* no key */
381 if (ret)
382 break;
383 case -ENOKEY: /* negative key */
384 ret = key_ref;
385 break;
386 default:
387 err = key_ref;
388 break;
389 }
390 }
391
392 /* search the session keyring */
393 if (cred->tgcred->session_keyring) {
394 rcu_read_lock();
395 key_ref = keyring_search_aux(
396 make_key_ref(rcu_dereference(
397 cred->tgcred->session_keyring),
398 1),
399 cred, type, description, match, no_state_check);
400 rcu_read_unlock();
401
402 if (!IS_ERR(key_ref))
403 goto found;
404
405 switch (PTR_ERR(key_ref)) {
406 case -EAGAIN: /* no key */
407 if (ret)
408 break;
409 case -ENOKEY: /* negative key */
410 ret = key_ref;
411 break;
412 default:
413 err = key_ref;
414 break;
415 }
416 }
417 /* or search the user-session keyring */
418 else if (cred->user->session_keyring) {
419 key_ref = keyring_search_aux(
420 make_key_ref(cred->user->session_keyring, 1),
421 cred, type, description, match, no_state_check);
422 if (!IS_ERR(key_ref))
423 goto found;
424
425 switch (PTR_ERR(key_ref)) {
426 case -EAGAIN: /* no key */
427 if (ret)
428 break;
429 case -ENOKEY: /* negative key */
430 ret = key_ref;
431 break;
432 default:
433 err = key_ref;
434 break;
435 }
436 }
437
438 /* no key - decide on the error we're going to go for */
439 key_ref = ret ? ret : err;
440
441found:
442 return key_ref;
443}
444
445/*
446 * Search the process keyrings attached to the supplied cred for the first
447 * matching key in the manner of search_my_process_keyrings(), but also search
448 * the keys attached to the assumed authorisation key using its credentials if
449 * one is available.
450 *
451 * Return same as search_my_process_keyrings().
452 */
453key_ref_t search_process_keyrings(struct key_type *type,
454 const void *description,
455 key_match_func_t match,
456 const struct cred *cred)
457{
458 struct request_key_auth *rka;
459 key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
460
461 might_sleep();
462
463 key_ref = search_my_process_keyrings(type, description, match,
464 false, cred);
465 if (!IS_ERR(key_ref))
466 goto found;
467 err = key_ref;
468
469 /* if this process has an instantiation authorisation key, then we also
470 * search the keyrings of the process mentioned there
471 * - we don't permit access to request_key auth keys via this method
472 */
473 if (cred->request_key_auth &&
474 cred == current_cred() &&
475 type != &key_type_request_key_auth
476 ) {
477 /* defend against the auth key being revoked */
478 down_read(&cred->request_key_auth->sem);
479
480 if (key_validate(cred->request_key_auth) == 0) {
481 rka = cred->request_key_auth->payload.data;
482
483 key_ref = search_process_keyrings(type, description,
484 match, rka->cred);
485
486 up_read(&cred->request_key_auth->sem);
487
488 if (!IS_ERR(key_ref))
489 goto found;
490
491 ret = key_ref;
492 } else {
493 up_read(&cred->request_key_auth->sem);
494 }
495 }
496
497 /* no key - decide on the error we're going to go for */
498 if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
499 key_ref = ERR_PTR(-ENOKEY);
500 else if (err == ERR_PTR(-EACCES))
501 key_ref = ret;
502 else
503 key_ref = err;
504
505found:
506 return key_ref;
507}
508
509/*
510 * See if the key we're looking at is the target key.
511 */
512int lookup_user_key_possessed(const struct key *key, const void *target)
513{
514 return key == target;
515}
516
517/*
518 * Look up a key ID given us by userspace with a given permissions mask to get
519 * the key it refers to.
520 *
521 * Flags can be passed to request that special keyrings be created if referred
522 * to directly, to permit partially constructed keys to be found and to skip
523 * validity and permission checks on the found key.
524 *
525 * Returns a pointer to the key with an incremented usage count if successful;
526 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
527 * to a key or the best found key was a negative key; -EKEYREVOKED or
528 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
529 * found key doesn't grant the requested permit or the LSM denied access to it;
530 * or -ENOMEM if a special keyring couldn't be created.
531 *
532 * In the case of a successful return, the possession attribute is set on the
533 * returned key reference.
534 */
535key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
536 key_perm_t perm)
537{
538 struct request_key_auth *rka;
539 const struct cred *cred;
540 struct key *key;
541 key_ref_t key_ref, skey_ref;
542 int ret;
543
544try_again:
545 cred = get_current_cred();
546 key_ref = ERR_PTR(-ENOKEY);
547
548 switch (id) {
549 case KEY_SPEC_THREAD_KEYRING:
550 if (!cred->thread_keyring) {
551 if (!(lflags & KEY_LOOKUP_CREATE))
552 goto error;
553
554 ret = install_thread_keyring();
555 if (ret < 0) {
556 key_ref = ERR_PTR(ret);
557 goto error;
558 }
559 goto reget_creds;
560 }
561
562 key = cred->thread_keyring;
563 atomic_inc(&key->usage);
564 key_ref = make_key_ref(key, 1);
565 break;
566
567 case KEY_SPEC_PROCESS_KEYRING:
568 if (!cred->tgcred->process_keyring) {
569 if (!(lflags & KEY_LOOKUP_CREATE))
570 goto error;
571
572 ret = install_process_keyring();
573 if (ret < 0) {
574 key_ref = ERR_PTR(ret);
575 goto error;
576 }
577 goto reget_creds;
578 }
579
580 key = cred->tgcred->process_keyring;
581 atomic_inc(&key->usage);
582 key_ref = make_key_ref(key, 1);
583 break;
584
585 case KEY_SPEC_SESSION_KEYRING:
586 if (!cred->tgcred->session_keyring) {
587 /* always install a session keyring upon access if one
588 * doesn't exist yet */
589 ret = install_user_keyrings();
590 if (ret < 0)
591 goto error;
592 if (lflags & KEY_LOOKUP_CREATE)
593 ret = join_session_keyring(NULL);
594 else
595 ret = install_session_keyring(
596 cred->user->session_keyring);
597
598 if (ret < 0)
599 goto error;
600 goto reget_creds;
601 } else if (cred->tgcred->session_keyring ==
602 cred->user->session_keyring &&
603 lflags & KEY_LOOKUP_CREATE) {
604 ret = join_session_keyring(NULL);
605 if (ret < 0)
606 goto error;
607 goto reget_creds;
608 }
609
610 rcu_read_lock();
611 key = rcu_dereference(cred->tgcred->session_keyring);
612 atomic_inc(&key->usage);
613 rcu_read_unlock();
614 key_ref = make_key_ref(key, 1);
615 break;
616
617 case KEY_SPEC_USER_KEYRING:
618 if (!cred->user->uid_keyring) {
619 ret = install_user_keyrings();
620 if (ret < 0)
621 goto error;
622 }
623
624 key = cred->user->uid_keyring;
625 atomic_inc(&key->usage);
626 key_ref = make_key_ref(key, 1);
627 break;
628
629 case KEY_SPEC_USER_SESSION_KEYRING:
630 if (!cred->user->session_keyring) {
631 ret = install_user_keyrings();
632 if (ret < 0)
633 goto error;
634 }
635
636 key = cred->user->session_keyring;
637 atomic_inc(&key->usage);
638 key_ref = make_key_ref(key, 1);
639 break;
640
641 case KEY_SPEC_GROUP_KEYRING:
642 /* group keyrings are not yet supported */
643 key_ref = ERR_PTR(-EINVAL);
644 goto error;
645
646 case KEY_SPEC_REQKEY_AUTH_KEY:
647 key = cred->request_key_auth;
648 if (!key)
649 goto error;
650
651 atomic_inc(&key->usage);
652 key_ref = make_key_ref(key, 1);
653 break;
654
655 case KEY_SPEC_REQUESTOR_KEYRING:
656 if (!cred->request_key_auth)
657 goto error;
658
659 down_read(&cred->request_key_auth->sem);
660 if (test_bit(KEY_FLAG_REVOKED,
661 &cred->request_key_auth->flags)) {
662 key_ref = ERR_PTR(-EKEYREVOKED);
663 key = NULL;
664 } else {
665 rka = cred->request_key_auth->payload.data;
666 key = rka->dest_keyring;
667 atomic_inc(&key->usage);
668 }
669 up_read(&cred->request_key_auth->sem);
670 if (!key)
671 goto error;
672 key_ref = make_key_ref(key, 1);
673 break;
674
675 default:
676 key_ref = ERR_PTR(-EINVAL);
677 if (id < 1)
678 goto error;
679
680 key = key_lookup(id);
681 if (IS_ERR(key)) {
682 key_ref = ERR_CAST(key);
683 goto error;
684 }
685
686 key_ref = make_key_ref(key, 0);
687
688 /* check to see if we possess the key */
689 skey_ref = search_process_keyrings(key->type, key,
690 lookup_user_key_possessed,
691 cred);
692
693 if (!IS_ERR(skey_ref)) {
694 key_put(key);
695 key_ref = skey_ref;
696 }
697
698 break;
699 }
700
701 /* unlink does not use the nominated key in any way, so can skip all
702 * the permission checks as it is only concerned with the keyring */
703 if (lflags & KEY_LOOKUP_FOR_UNLINK) {
704 ret = 0;
705 goto error;
706 }
707
708 if (!(lflags & KEY_LOOKUP_PARTIAL)) {
709 ret = wait_for_key_construction(key, true);
710 switch (ret) {
711 case -ERESTARTSYS:
712 goto invalid_key;
713 default:
714 if (perm)
715 goto invalid_key;
716 case 0:
717 break;
718 }
719 } else if (perm) {
720 ret = key_validate(key);
721 if (ret < 0)
722 goto invalid_key;
723 }
724
725 ret = -EIO;
726 if (!(lflags & KEY_LOOKUP_PARTIAL) &&
727 !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
728 goto invalid_key;
729
730 /* check the permissions */
731 ret = key_task_permission(key_ref, cred, perm);
732 if (ret < 0)
733 goto invalid_key;
734
735 key->last_used_at = current_kernel_time().tv_sec;
736
737error:
738 put_cred(cred);
739 return key_ref;
740
741invalid_key:
742 key_ref_put(key_ref);
743 key_ref = ERR_PTR(ret);
744 goto error;
745
746 /* if we attempted to install a keyring, then it may have caused new
747 * creds to be installed */
748reget_creds:
749 put_cred(cred);
750 goto try_again;
751}
752
753/*
754 * Join the named keyring as the session keyring if possible else attempt to
755 * create a new one of that name and join that.
756 *
757 * If the name is NULL, an empty anonymous keyring will be installed as the
758 * session keyring.
759 *
760 * Named session keyrings are joined with a semaphore held to prevent the
761 * keyrings from going away whilst the attempt is made to going them and also
762 * to prevent a race in creating compatible session keyrings.
763 */
764long join_session_keyring(const char *name)
765{
766 const struct cred *old;
767 struct cred *new;
768 struct key *keyring;
769 long ret, serial;
770
771 /* only permit this if there's a single thread in the thread group -
772 * this avoids us having to adjust the creds on all threads and risking
773 * ENOMEM */
774 if (!current_is_single_threaded())
775 return -EMLINK;
776
777 new = prepare_creds();
778 if (!new)
779 return -ENOMEM;
780 old = current_cred();
781
782 /* if no name is provided, install an anonymous keyring */
783 if (!name) {
784 ret = install_session_keyring_to_cred(new, NULL);
785 if (ret < 0)
786 goto error;
787
788 serial = new->tgcred->session_keyring->serial;
789 ret = commit_creds(new);
790 if (ret == 0)
791 ret = serial;
792 goto okay;
793 }
794
795 /* allow the user to join or create a named keyring */
796 mutex_lock(&key_session_mutex);
797
798 /* look for an existing keyring of this name */
799 keyring = find_keyring_by_name(name, false);
800 if (PTR_ERR(keyring) == -ENOKEY) {
801 /* not found - try and create a new one */
802 keyring = keyring_alloc(name, old->uid, old->gid, old,
803 KEY_ALLOC_IN_QUOTA, NULL);
804 if (IS_ERR(keyring)) {
805 ret = PTR_ERR(keyring);
806 goto error2;
807 }
808 } else if (IS_ERR(keyring)) {
809 ret = PTR_ERR(keyring);
810 goto error2;
811 }
812
813 /* we've got a keyring - now to install it */
814 ret = install_session_keyring_to_cred(new, keyring);
815 if (ret < 0)
816 goto error2;
817
818 commit_creds(new);
819 mutex_unlock(&key_session_mutex);
820
821 ret = keyring->serial;
822 key_put(keyring);
823okay:
824 return ret;
825
826error2:
827 mutex_unlock(&key_session_mutex);
828error:
829 abort_creds(new);
830 return ret;
831}
832
833/*
834 * Replace a process's session keyring on behalf of one of its children when
835 * the target process is about to resume userspace execution.
836 */
837void key_change_session_keyring(struct task_work *twork)
838{
839 const struct cred *old = current_cred();
840 struct cred *new = twork->data;
841
842 kfree(twork);
843 if (unlikely(current->flags & PF_EXITING)) {
844 put_cred(new);
845 return;
846 }
847
848 new-> uid = old-> uid;
849 new-> euid = old-> euid;
850 new-> suid = old-> suid;
851 new->fsuid = old->fsuid;
852 new-> gid = old-> gid;
853 new-> egid = old-> egid;
854 new-> sgid = old-> sgid;
855 new->fsgid = old->fsgid;
856 new->user = get_uid(old->user);
857 new->user_ns = get_user_ns(new->user_ns);
858 new->group_info = get_group_info(old->group_info);
859
860 new->securebits = old->securebits;
861 new->cap_inheritable = old->cap_inheritable;
862 new->cap_permitted = old->cap_permitted;
863 new->cap_effective = old->cap_effective;
864 new->cap_bset = old->cap_bset;
865
866 new->jit_keyring = old->jit_keyring;
867 new->thread_keyring = key_get(old->thread_keyring);
868 new->tgcred->tgid = old->tgcred->tgid;
869 new->tgcred->process_keyring = key_get(old->tgcred->process_keyring);
870
871 security_transfer_creds(new, old);
872
873 commit_creds(new);
874}