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