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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 = GLOBAL_ROOT_UID,
38};
39
40/*
41 * Install the user and user session keyrings for the current process's UID.
42 */
43int 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
117error_release_both:
118 key_put(session_keyring);
119error_release:
120 key_put(uid_keyring);
121error:
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 */
131int 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 */
148static 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 */
174int 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 */
198static 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 */
219int 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 __key_get(keyring);
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 */
255static 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 */
276void 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 */
290void 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 */
322key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx)
323{
324 key_ref_t key_ref, ret, err;
325
326 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
327 * searchable, but we failed to find a key or we found a negative key;
328 * otherwise we want to return a sample error (probably -EACCES) if
329 * none of the keyrings were searchable
330 *
331 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
332 */
333 key_ref = NULL;
334 ret = NULL;
335 err = ERR_PTR(-EAGAIN);
336
337 /* search the thread keyring first */
338 if (ctx->cred->thread_keyring) {
339 key_ref = keyring_search_aux(
340 make_key_ref(ctx->cred->thread_keyring, 1), ctx);
341 if (!IS_ERR(key_ref))
342 goto found;
343
344 switch (PTR_ERR(key_ref)) {
345 case -EAGAIN: /* no key */
346 case -ENOKEY: /* negative key */
347 ret = key_ref;
348 break;
349 default:
350 err = key_ref;
351 break;
352 }
353 }
354
355 /* search the process keyring second */
356 if (ctx->cred->process_keyring) {
357 key_ref = keyring_search_aux(
358 make_key_ref(ctx->cred->process_keyring, 1), ctx);
359 if (!IS_ERR(key_ref))
360 goto found;
361
362 switch (PTR_ERR(key_ref)) {
363 case -EAGAIN: /* no key */
364 if (ret)
365 break;
366 case -ENOKEY: /* negative key */
367 ret = key_ref;
368 break;
369 default:
370 err = key_ref;
371 break;
372 }
373 }
374
375 /* search the session keyring */
376 if (ctx->cred->session_keyring) {
377 rcu_read_lock();
378 key_ref = keyring_search_aux(
379 make_key_ref(rcu_dereference(ctx->cred->session_keyring), 1),
380 ctx);
381 rcu_read_unlock();
382
383 if (!IS_ERR(key_ref))
384 goto found;
385
386 switch (PTR_ERR(key_ref)) {
387 case -EAGAIN: /* no key */
388 if (ret)
389 break;
390 case -ENOKEY: /* negative key */
391 ret = key_ref;
392 break;
393 default:
394 err = key_ref;
395 break;
396 }
397 }
398 /* or search the user-session keyring */
399 else if (ctx->cred->user->session_keyring) {
400 key_ref = keyring_search_aux(
401 make_key_ref(ctx->cred->user->session_keyring, 1),
402 ctx);
403 if (!IS_ERR(key_ref))
404 goto found;
405
406 switch (PTR_ERR(key_ref)) {
407 case -EAGAIN: /* no key */
408 if (ret)
409 break;
410 case -ENOKEY: /* negative key */
411 ret = key_ref;
412 break;
413 default:
414 err = key_ref;
415 break;
416 }
417 }
418
419 /* no key - decide on the error we're going to go for */
420 key_ref = ret ? ret : err;
421
422found:
423 return key_ref;
424}
425
426/*
427 * Search the process keyrings attached to the supplied cred for the first
428 * matching key in the manner of search_my_process_keyrings(), but also search
429 * the keys attached to the assumed authorisation key using its credentials if
430 * one is available.
431 *
432 * Return same as search_my_process_keyrings().
433 */
434key_ref_t search_process_keyrings(struct keyring_search_context *ctx)
435{
436 struct request_key_auth *rka;
437 key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
438
439 might_sleep();
440
441 key_ref = search_my_process_keyrings(ctx);
442 if (!IS_ERR(key_ref))
443 goto found;
444 err = key_ref;
445
446 /* if this process has an instantiation authorisation key, then we also
447 * search the keyrings of the process mentioned there
448 * - we don't permit access to request_key auth keys via this method
449 */
450 if (ctx->cred->request_key_auth &&
451 ctx->cred == current_cred() &&
452 ctx->index_key.type != &key_type_request_key_auth
453 ) {
454 const struct cred *cred = ctx->cred;
455
456 /* defend against the auth key being revoked */
457 down_read(&cred->request_key_auth->sem);
458
459 if (key_validate(ctx->cred->request_key_auth) == 0) {
460 rka = ctx->cred->request_key_auth->payload.data[0];
461
462 ctx->cred = rka->cred;
463 key_ref = search_process_keyrings(ctx);
464 ctx->cred = cred;
465
466 up_read(&cred->request_key_auth->sem);
467
468 if (!IS_ERR(key_ref))
469 goto found;
470
471 ret = key_ref;
472 } else {
473 up_read(&cred->request_key_auth->sem);
474 }
475 }
476
477 /* no key - decide on the error we're going to go for */
478 if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
479 key_ref = ERR_PTR(-ENOKEY);
480 else if (err == ERR_PTR(-EACCES))
481 key_ref = ret;
482 else
483 key_ref = err;
484
485found:
486 return key_ref;
487}
488
489/*
490 * See if the key we're looking at is the target key.
491 */
492bool lookup_user_key_possessed(const struct key *key,
493 const struct key_match_data *match_data)
494{
495 return key == match_data->raw_data;
496}
497
498/*
499 * Look up a key ID given us by userspace with a given permissions mask to get
500 * the key it refers to.
501 *
502 * Flags can be passed to request that special keyrings be created if referred
503 * to directly, to permit partially constructed keys to be found and to skip
504 * validity and permission checks on the found key.
505 *
506 * Returns a pointer to the key with an incremented usage count if successful;
507 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
508 * to a key or the best found key was a negative key; -EKEYREVOKED or
509 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
510 * found key doesn't grant the requested permit or the LSM denied access to it;
511 * or -ENOMEM if a special keyring couldn't be created.
512 *
513 * In the case of a successful return, the possession attribute is set on the
514 * returned key reference.
515 */
516key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
517 key_perm_t perm)
518{
519 struct keyring_search_context ctx = {
520 .match_data.cmp = lookup_user_key_possessed,
521 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
522 .flags = KEYRING_SEARCH_NO_STATE_CHECK,
523 };
524 struct request_key_auth *rka;
525 struct key *key;
526 key_ref_t key_ref, skey_ref;
527 int ret;
528
529try_again:
530 ctx.cred = get_current_cred();
531 key_ref = ERR_PTR(-ENOKEY);
532
533 switch (id) {
534 case KEY_SPEC_THREAD_KEYRING:
535 if (!ctx.cred->thread_keyring) {
536 if (!(lflags & KEY_LOOKUP_CREATE))
537 goto error;
538
539 ret = install_thread_keyring();
540 if (ret < 0) {
541 key_ref = ERR_PTR(ret);
542 goto error;
543 }
544 goto reget_creds;
545 }
546
547 key = ctx.cred->thread_keyring;
548 __key_get(key);
549 key_ref = make_key_ref(key, 1);
550 break;
551
552 case KEY_SPEC_PROCESS_KEYRING:
553 if (!ctx.cred->process_keyring) {
554 if (!(lflags & KEY_LOOKUP_CREATE))
555 goto error;
556
557 ret = install_process_keyring();
558 if (ret < 0) {
559 key_ref = ERR_PTR(ret);
560 goto error;
561 }
562 goto reget_creds;
563 }
564
565 key = ctx.cred->process_keyring;
566 __key_get(key);
567 key_ref = make_key_ref(key, 1);
568 break;
569
570 case KEY_SPEC_SESSION_KEYRING:
571 if (!ctx.cred->session_keyring) {
572 /* always install a session keyring upon access if one
573 * doesn't exist yet */
574 ret = install_user_keyrings();
575 if (ret < 0)
576 goto error;
577 if (lflags & KEY_LOOKUP_CREATE)
578 ret = join_session_keyring(NULL);
579 else
580 ret = install_session_keyring(
581 ctx.cred->user->session_keyring);
582
583 if (ret < 0)
584 goto error;
585 goto reget_creds;
586 } else if (ctx.cred->session_keyring ==
587 ctx.cred->user->session_keyring &&
588 lflags & KEY_LOOKUP_CREATE) {
589 ret = join_session_keyring(NULL);
590 if (ret < 0)
591 goto error;
592 goto reget_creds;
593 }
594
595 rcu_read_lock();
596 key = rcu_dereference(ctx.cred->session_keyring);
597 __key_get(key);
598 rcu_read_unlock();
599 key_ref = make_key_ref(key, 1);
600 break;
601
602 case KEY_SPEC_USER_KEYRING:
603 if (!ctx.cred->user->uid_keyring) {
604 ret = install_user_keyrings();
605 if (ret < 0)
606 goto error;
607 }
608
609 key = ctx.cred->user->uid_keyring;
610 __key_get(key);
611 key_ref = make_key_ref(key, 1);
612 break;
613
614 case KEY_SPEC_USER_SESSION_KEYRING:
615 if (!ctx.cred->user->session_keyring) {
616 ret = install_user_keyrings();
617 if (ret < 0)
618 goto error;
619 }
620
621 key = ctx.cred->user->session_keyring;
622 __key_get(key);
623 key_ref = make_key_ref(key, 1);
624 break;
625
626 case KEY_SPEC_GROUP_KEYRING:
627 /* group keyrings are not yet supported */
628 key_ref = ERR_PTR(-EINVAL);
629 goto error;
630
631 case KEY_SPEC_REQKEY_AUTH_KEY:
632 key = ctx.cred->request_key_auth;
633 if (!key)
634 goto error;
635
636 __key_get(key);
637 key_ref = make_key_ref(key, 1);
638 break;
639
640 case KEY_SPEC_REQUESTOR_KEYRING:
641 if (!ctx.cred->request_key_auth)
642 goto error;
643
644 down_read(&ctx.cred->request_key_auth->sem);
645 if (test_bit(KEY_FLAG_REVOKED,
646 &ctx.cred->request_key_auth->flags)) {
647 key_ref = ERR_PTR(-EKEYREVOKED);
648 key = NULL;
649 } else {
650 rka = ctx.cred->request_key_auth->payload.data[0];
651 key = rka->dest_keyring;
652 __key_get(key);
653 }
654 up_read(&ctx.cred->request_key_auth->sem);
655 if (!key)
656 goto error;
657 key_ref = make_key_ref(key, 1);
658 break;
659
660 default:
661 key_ref = ERR_PTR(-EINVAL);
662 if (id < 1)
663 goto error;
664
665 key = key_lookup(id);
666 if (IS_ERR(key)) {
667 key_ref = ERR_CAST(key);
668 goto error;
669 }
670
671 key_ref = make_key_ref(key, 0);
672
673 /* check to see if we possess the key */
674 ctx.index_key.type = key->type;
675 ctx.index_key.description = key->description;
676 ctx.index_key.desc_len = strlen(key->description);
677 ctx.match_data.raw_data = key;
678 kdebug("check possessed");
679 skey_ref = search_process_keyrings(&ctx);
680 kdebug("possessed=%p", skey_ref);
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, ctx.cred, perm);
721 if (ret < 0)
722 goto invalid_key;
723
724 key->last_used_at = current_kernel_time().tv_sec;
725
726error:
727 put_cred(ctx.cred);
728 return key_ref;
729
730invalid_key:
731 key_ref_put(key_ref);
732 key_ref = ERR_PTR(ret);
733 goto error;
734
735 /* if we attempted to install a keyring, then it may have caused new
736 * creds to be installed */
737reget_creds:
738 put_cred(ctx.cred);
739 goto try_again;
740}
741
742/*
743 * Join the named keyring as the session keyring if possible else attempt to
744 * create a new one of that name and join that.
745 *
746 * If the name is NULL, an empty anonymous keyring will be installed as the
747 * session keyring.
748 *
749 * Named session keyrings are joined with a semaphore held to prevent the
750 * keyrings from going away whilst the attempt is made to going them and also
751 * to prevent a race in creating compatible session keyrings.
752 */
753long join_session_keyring(const char *name)
754{
755 const struct cred *old;
756 struct cred *new;
757 struct key *keyring;
758 long ret, serial;
759
760 new = prepare_creds();
761 if (!new)
762 return -ENOMEM;
763 old = current_cred();
764
765 /* if no name is provided, install an anonymous keyring */
766 if (!name) {
767 ret = install_session_keyring_to_cred(new, NULL);
768 if (ret < 0)
769 goto error;
770
771 serial = new->session_keyring->serial;
772 ret = commit_creds(new);
773 if (ret == 0)
774 ret = serial;
775 goto okay;
776 }
777
778 /* allow the user to join or create a named keyring */
779 mutex_lock(&key_session_mutex);
780
781 /* look for an existing keyring of this name */
782 keyring = find_keyring_by_name(name, false);
783 if (PTR_ERR(keyring) == -ENOKEY) {
784 /* not found - try and create a new one */
785 keyring = keyring_alloc(
786 name, old->uid, old->gid, old,
787 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_LINK,
788 KEY_ALLOC_IN_QUOTA, NULL);
789 if (IS_ERR(keyring)) {
790 ret = PTR_ERR(keyring);
791 goto error2;
792 }
793 } else if (IS_ERR(keyring)) {
794 ret = PTR_ERR(keyring);
795 goto error2;
796 } else if (keyring == new->session_keyring) {
797 key_put(keyring);
798 ret = 0;
799 goto error2;
800 }
801
802 /* we've got a keyring - now to install it */
803 ret = install_session_keyring_to_cred(new, keyring);
804 if (ret < 0)
805 goto error2;
806
807 commit_creds(new);
808 mutex_unlock(&key_session_mutex);
809
810 ret = keyring->serial;
811 key_put(keyring);
812okay:
813 return ret;
814
815error2:
816 mutex_unlock(&key_session_mutex);
817error:
818 abort_creds(new);
819 return ret;
820}
821
822/*
823 * Replace a process's session keyring on behalf of one of its children when
824 * the target process is about to resume userspace execution.
825 */
826void key_change_session_keyring(struct callback_head *twork)
827{
828 const struct cred *old = current_cred();
829 struct cred *new = container_of(twork, struct cred, rcu);
830
831 if (unlikely(current->flags & PF_EXITING)) {
832 put_cred(new);
833 return;
834 }
835
836 new-> uid = old-> uid;
837 new-> euid = old-> euid;
838 new-> suid = old-> suid;
839 new->fsuid = old->fsuid;
840 new-> gid = old-> gid;
841 new-> egid = old-> egid;
842 new-> sgid = old-> sgid;
843 new->fsgid = old->fsgid;
844 new->user = get_uid(old->user);
845 new->user_ns = get_user_ns(old->user_ns);
846 new->group_info = get_group_info(old->group_info);
847
848 new->securebits = old->securebits;
849 new->cap_inheritable = old->cap_inheritable;
850 new->cap_permitted = old->cap_permitted;
851 new->cap_effective = old->cap_effective;
852 new->cap_ambient = old->cap_ambient;
853 new->cap_bset = old->cap_bset;
854
855 new->jit_keyring = old->jit_keyring;
856 new->thread_keyring = key_get(old->thread_keyring);
857 new->process_keyring = key_get(old->process_keyring);
858
859 security_transfer_creds(new, old);
860
861 commit_creds(new);
862}
863
864/*
865 * Make sure that root's user and user-session keyrings exist.
866 */
867static int __init init_root_keyring(void)
868{
869 return install_user_keyrings();
870}
871
872late_initcall(init_root_keyring);
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 = GLOBAL_ROOT_UID,
38};
39
40/*
41 * Install the user and user session keyrings for the current process's UID.
42 */
43int 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
117error_release_both:
118 key_put(session_keyring);
119error_release:
120 key_put(uid_keyring);
121error:
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 */
131int 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 */
148static 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 */
174int 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 */
198static 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 */
219int 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 __key_get(keyring);
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 */
255static 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 */
276void 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 */
290void 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 */
322key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx)
323{
324 key_ref_t key_ref, ret, err;
325
326 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
327 * searchable, but we failed to find a key or we found a negative key;
328 * otherwise we want to return a sample error (probably -EACCES) if
329 * none of the keyrings were searchable
330 *
331 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
332 */
333 key_ref = NULL;
334 ret = NULL;
335 err = ERR_PTR(-EAGAIN);
336
337 /* search the thread keyring first */
338 if (ctx->cred->thread_keyring) {
339 key_ref = keyring_search_aux(
340 make_key_ref(ctx->cred->thread_keyring, 1), ctx);
341 if (!IS_ERR(key_ref))
342 goto found;
343
344 switch (PTR_ERR(key_ref)) {
345 case -EAGAIN: /* no key */
346 case -ENOKEY: /* negative key */
347 ret = key_ref;
348 break;
349 default:
350 err = key_ref;
351 break;
352 }
353 }
354
355 /* search the process keyring second */
356 if (ctx->cred->process_keyring) {
357 key_ref = keyring_search_aux(
358 make_key_ref(ctx->cred->process_keyring, 1), ctx);
359 if (!IS_ERR(key_ref))
360 goto found;
361
362 switch (PTR_ERR(key_ref)) {
363 case -EAGAIN: /* no key */
364 if (ret)
365 break;
366 case -ENOKEY: /* negative key */
367 ret = key_ref;
368 break;
369 default:
370 err = key_ref;
371 break;
372 }
373 }
374
375 /* search the session keyring */
376 if (ctx->cred->session_keyring) {
377 rcu_read_lock();
378 key_ref = keyring_search_aux(
379 make_key_ref(rcu_dereference(ctx->cred->session_keyring), 1),
380 ctx);
381 rcu_read_unlock();
382
383 if (!IS_ERR(key_ref))
384 goto found;
385
386 switch (PTR_ERR(key_ref)) {
387 case -EAGAIN: /* no key */
388 if (ret)
389 break;
390 case -ENOKEY: /* negative key */
391 ret = key_ref;
392 break;
393 default:
394 err = key_ref;
395 break;
396 }
397 }
398 /* or search the user-session keyring */
399 else if (ctx->cred->user->session_keyring) {
400 key_ref = keyring_search_aux(
401 make_key_ref(ctx->cred->user->session_keyring, 1),
402 ctx);
403 if (!IS_ERR(key_ref))
404 goto found;
405
406 switch (PTR_ERR(key_ref)) {
407 case -EAGAIN: /* no key */
408 if (ret)
409 break;
410 case -ENOKEY: /* negative key */
411 ret = key_ref;
412 break;
413 default:
414 err = key_ref;
415 break;
416 }
417 }
418
419 /* no key - decide on the error we're going to go for */
420 key_ref = ret ? ret : err;
421
422found:
423 return key_ref;
424}
425
426/*
427 * Search the process keyrings attached to the supplied cred for the first
428 * matching key in the manner of search_my_process_keyrings(), but also search
429 * the keys attached to the assumed authorisation key using its credentials if
430 * one is available.
431 *
432 * Return same as search_my_process_keyrings().
433 */
434key_ref_t search_process_keyrings(struct keyring_search_context *ctx)
435{
436 struct request_key_auth *rka;
437 key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
438
439 might_sleep();
440
441 key_ref = search_my_process_keyrings(ctx);
442 if (!IS_ERR(key_ref))
443 goto found;
444 err = key_ref;
445
446 /* if this process has an instantiation authorisation key, then we also
447 * search the keyrings of the process mentioned there
448 * - we don't permit access to request_key auth keys via this method
449 */
450 if (ctx->cred->request_key_auth &&
451 ctx->cred == current_cred() &&
452 ctx->index_key.type != &key_type_request_key_auth
453 ) {
454 const struct cred *cred = ctx->cred;
455
456 /* defend against the auth key being revoked */
457 down_read(&cred->request_key_auth->sem);
458
459 if (key_validate(ctx->cred->request_key_auth) == 0) {
460 rka = ctx->cred->request_key_auth->payload.data;
461
462 ctx->cred = rka->cred;
463 key_ref = search_process_keyrings(ctx);
464 ctx->cred = cred;
465
466 up_read(&cred->request_key_auth->sem);
467
468 if (!IS_ERR(key_ref))
469 goto found;
470
471 ret = key_ref;
472 } else {
473 up_read(&cred->request_key_auth->sem);
474 }
475 }
476
477 /* no key - decide on the error we're going to go for */
478 if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
479 key_ref = ERR_PTR(-ENOKEY);
480 else if (err == ERR_PTR(-EACCES))
481 key_ref = ret;
482 else
483 key_ref = err;
484
485found:
486 return key_ref;
487}
488
489/*
490 * See if the key we're looking at is the target key.
491 */
492int lookup_user_key_possessed(const struct key *key, const void *target)
493{
494 return key == target;
495}
496
497/*
498 * Look up a key ID given us by userspace with a given permissions mask to get
499 * the key it refers to.
500 *
501 * Flags can be passed to request that special keyrings be created if referred
502 * to directly, to permit partially constructed keys to be found and to skip
503 * validity and permission checks on the found key.
504 *
505 * Returns a pointer to the key with an incremented usage count if successful;
506 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
507 * to a key or the best found key was a negative key; -EKEYREVOKED or
508 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
509 * found key doesn't grant the requested permit or the LSM denied access to it;
510 * or -ENOMEM if a special keyring couldn't be created.
511 *
512 * In the case of a successful return, the possession attribute is set on the
513 * returned key reference.
514 */
515key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
516 key_perm_t perm)
517{
518 struct keyring_search_context ctx = {
519 .match = lookup_user_key_possessed,
520 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
521 KEYRING_SEARCH_LOOKUP_DIRECT),
522 };
523 struct request_key_auth *rka;
524 struct key *key;
525 key_ref_t key_ref, skey_ref;
526 int ret;
527
528try_again:
529 ctx.cred = get_current_cred();
530 key_ref = ERR_PTR(-ENOKEY);
531
532 switch (id) {
533 case KEY_SPEC_THREAD_KEYRING:
534 if (!ctx.cred->thread_keyring) {
535 if (!(lflags & KEY_LOOKUP_CREATE))
536 goto error;
537
538 ret = install_thread_keyring();
539 if (ret < 0) {
540 key_ref = ERR_PTR(ret);
541 goto error;
542 }
543 goto reget_creds;
544 }
545
546 key = ctx.cred->thread_keyring;
547 __key_get(key);
548 key_ref = make_key_ref(key, 1);
549 break;
550
551 case KEY_SPEC_PROCESS_KEYRING:
552 if (!ctx.cred->process_keyring) {
553 if (!(lflags & KEY_LOOKUP_CREATE))
554 goto error;
555
556 ret = install_process_keyring();
557 if (ret < 0) {
558 key_ref = ERR_PTR(ret);
559 goto error;
560 }
561 goto reget_creds;
562 }
563
564 key = ctx.cred->process_keyring;
565 __key_get(key);
566 key_ref = make_key_ref(key, 1);
567 break;
568
569 case KEY_SPEC_SESSION_KEYRING:
570 if (!ctx.cred->session_keyring) {
571 /* always install a session keyring upon access if one
572 * doesn't exist yet */
573 ret = install_user_keyrings();
574 if (ret < 0)
575 goto error;
576 if (lflags & KEY_LOOKUP_CREATE)
577 ret = join_session_keyring(NULL);
578 else
579 ret = install_session_keyring(
580 ctx.cred->user->session_keyring);
581
582 if (ret < 0)
583 goto error;
584 goto reget_creds;
585 } else if (ctx.cred->session_keyring ==
586 ctx.cred->user->session_keyring &&
587 lflags & KEY_LOOKUP_CREATE) {
588 ret = join_session_keyring(NULL);
589 if (ret < 0)
590 goto error;
591 goto reget_creds;
592 }
593
594 rcu_read_lock();
595 key = rcu_dereference(ctx.cred->session_keyring);
596 __key_get(key);
597 rcu_read_unlock();
598 key_ref = make_key_ref(key, 1);
599 break;
600
601 case KEY_SPEC_USER_KEYRING:
602 if (!ctx.cred->user->uid_keyring) {
603 ret = install_user_keyrings();
604 if (ret < 0)
605 goto error;
606 }
607
608 key = ctx.cred->user->uid_keyring;
609 __key_get(key);
610 key_ref = make_key_ref(key, 1);
611 break;
612
613 case KEY_SPEC_USER_SESSION_KEYRING:
614 if (!ctx.cred->user->session_keyring) {
615 ret = install_user_keyrings();
616 if (ret < 0)
617 goto error;
618 }
619
620 key = ctx.cred->user->session_keyring;
621 __key_get(key);
622 key_ref = make_key_ref(key, 1);
623 break;
624
625 case KEY_SPEC_GROUP_KEYRING:
626 /* group keyrings are not yet supported */
627 key_ref = ERR_PTR(-EINVAL);
628 goto error;
629
630 case KEY_SPEC_REQKEY_AUTH_KEY:
631 key = ctx.cred->request_key_auth;
632 if (!key)
633 goto error;
634
635 __key_get(key);
636 key_ref = make_key_ref(key, 1);
637 break;
638
639 case KEY_SPEC_REQUESTOR_KEYRING:
640 if (!ctx.cred->request_key_auth)
641 goto error;
642
643 down_read(&ctx.cred->request_key_auth->sem);
644 if (test_bit(KEY_FLAG_REVOKED,
645 &ctx.cred->request_key_auth->flags)) {
646 key_ref = ERR_PTR(-EKEYREVOKED);
647 key = NULL;
648 } else {
649 rka = ctx.cred->request_key_auth->payload.data;
650 key = rka->dest_keyring;
651 __key_get(key);
652 }
653 up_read(&ctx.cred->request_key_auth->sem);
654 if (!key)
655 goto error;
656 key_ref = make_key_ref(key, 1);
657 break;
658
659 default:
660 key_ref = ERR_PTR(-EINVAL);
661 if (id < 1)
662 goto error;
663
664 key = key_lookup(id);
665 if (IS_ERR(key)) {
666 key_ref = ERR_CAST(key);
667 goto error;
668 }
669
670 key_ref = make_key_ref(key, 0);
671
672 /* check to see if we possess the key */
673 ctx.index_key.type = key->type;
674 ctx.index_key.description = key->description;
675 ctx.index_key.desc_len = strlen(key->description);
676 ctx.match_data = key;
677 kdebug("check possessed");
678 skey_ref = search_process_keyrings(&ctx);
679 kdebug("possessed=%p", skey_ref);
680
681 if (!IS_ERR(skey_ref)) {
682 key_put(key);
683 key_ref = skey_ref;
684 }
685
686 break;
687 }
688
689 /* unlink does not use the nominated key in any way, so can skip all
690 * the permission checks as it is only concerned with the keyring */
691 if (lflags & KEY_LOOKUP_FOR_UNLINK) {
692 ret = 0;
693 goto error;
694 }
695
696 if (!(lflags & KEY_LOOKUP_PARTIAL)) {
697 ret = wait_for_key_construction(key, true);
698 switch (ret) {
699 case -ERESTARTSYS:
700 goto invalid_key;
701 default:
702 if (perm)
703 goto invalid_key;
704 case 0:
705 break;
706 }
707 } else if (perm) {
708 ret = key_validate(key);
709 if (ret < 0)
710 goto invalid_key;
711 }
712
713 ret = -EIO;
714 if (!(lflags & KEY_LOOKUP_PARTIAL) &&
715 !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
716 goto invalid_key;
717
718 /* check the permissions */
719 ret = key_task_permission(key_ref, ctx.cred, perm);
720 if (ret < 0)
721 goto invalid_key;
722
723 key->last_used_at = current_kernel_time().tv_sec;
724
725error:
726 put_cred(ctx.cred);
727 return key_ref;
728
729invalid_key:
730 key_ref_put(key_ref);
731 key_ref = ERR_PTR(ret);
732 goto error;
733
734 /* if we attempted to install a keyring, then it may have caused new
735 * creds to be installed */
736reget_creds:
737 put_cred(ctx.cred);
738 goto try_again;
739}
740
741/*
742 * Join the named keyring as the session keyring if possible else attempt to
743 * create a new one of that name and join that.
744 *
745 * If the name is NULL, an empty anonymous keyring will be installed as the
746 * session keyring.
747 *
748 * Named session keyrings are joined with a semaphore held to prevent the
749 * keyrings from going away whilst the attempt is made to going them and also
750 * to prevent a race in creating compatible session keyrings.
751 */
752long join_session_keyring(const char *name)
753{
754 const struct cred *old;
755 struct cred *new;
756 struct key *keyring;
757 long ret, serial;
758
759 new = prepare_creds();
760 if (!new)
761 return -ENOMEM;
762 old = current_cred();
763
764 /* if no name is provided, install an anonymous keyring */
765 if (!name) {
766 ret = install_session_keyring_to_cred(new, NULL);
767 if (ret < 0)
768 goto error;
769
770 serial = new->session_keyring->serial;
771 ret = commit_creds(new);
772 if (ret == 0)
773 ret = serial;
774 goto okay;
775 }
776
777 /* allow the user to join or create a named keyring */
778 mutex_lock(&key_session_mutex);
779
780 /* look for an existing keyring of this name */
781 keyring = find_keyring_by_name(name, false);
782 if (PTR_ERR(keyring) == -ENOKEY) {
783 /* not found - try and create a new one */
784 keyring = keyring_alloc(
785 name, old->uid, old->gid, old,
786 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_LINK,
787 KEY_ALLOC_IN_QUOTA, NULL);
788 if (IS_ERR(keyring)) {
789 ret = PTR_ERR(keyring);
790 goto error2;
791 }
792 } else if (IS_ERR(keyring)) {
793 ret = PTR_ERR(keyring);
794 goto error2;
795 } else if (keyring == new->session_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);
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_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_bset = old->cap_bset;
851
852 new->jit_keyring = old->jit_keyring;
853 new->thread_keyring = key_get(old->thread_keyring);
854 new->process_keyring = key_get(old->process_keyring);
855
856 security_transfer_creds(new, old);
857
858 commit_creds(new);
859}
860
861/*
862 * Make sure that root's user and user-session keyrings exist.
863 */
864static int __init init_root_keyring(void)
865{
866 return install_user_keyrings();
867}
868
869late_initcall(init_root_keyring);