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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 <linux/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,
80 NULL, NULL);
81 if (IS_ERR(uid_keyring)) {
82 ret = PTR_ERR(uid_keyring);
83 goto error;
84 }
85 }
86
87 /* get a default session keyring (which might also exist
88 * already) */
89 sprintf(buf, "_uid_ses.%u", uid);
90
91 session_keyring = find_keyring_by_name(buf, true);
92 if (IS_ERR(session_keyring)) {
93 session_keyring =
94 keyring_alloc(buf, user->uid, INVALID_GID,
95 cred, user_keyring_perm,
96 KEY_ALLOC_IN_QUOTA,
97 NULL, NULL);
98 if (IS_ERR(session_keyring)) {
99 ret = PTR_ERR(session_keyring);
100 goto error_release;
101 }
102
103 /* we install a link from the user session keyring to
104 * the user keyring */
105 ret = key_link(session_keyring, uid_keyring);
106 if (ret < 0)
107 goto error_release_both;
108 }
109
110 /* install the keyrings */
111 user->uid_keyring = uid_keyring;
112 user->session_keyring = session_keyring;
113 }
114
115 mutex_unlock(&key_user_keyring_mutex);
116 kleave(" = 0");
117 return 0;
118
119error_release_both:
120 key_put(session_keyring);
121error_release:
122 key_put(uid_keyring);
123error:
124 mutex_unlock(&key_user_keyring_mutex);
125 kleave(" = %d", ret);
126 return ret;
127}
128
129/*
130 * Install a fresh thread keyring directly to new credentials. This keyring is
131 * allowed to overrun the quota.
132 */
133int install_thread_keyring_to_cred(struct cred *new)
134{
135 struct key *keyring;
136
137 keyring = keyring_alloc("_tid", new->uid, new->gid, new,
138 KEY_POS_ALL | KEY_USR_VIEW,
139 KEY_ALLOC_QUOTA_OVERRUN,
140 NULL, NULL);
141 if (IS_ERR(keyring))
142 return PTR_ERR(keyring);
143
144 new->thread_keyring = keyring;
145 return 0;
146}
147
148/*
149 * Install a fresh thread keyring, discarding the old one.
150 */
151static int install_thread_keyring(void)
152{
153 struct cred *new;
154 int ret;
155
156 new = prepare_creds();
157 if (!new)
158 return -ENOMEM;
159
160 BUG_ON(new->thread_keyring);
161
162 ret = install_thread_keyring_to_cred(new);
163 if (ret < 0) {
164 abort_creds(new);
165 return ret;
166 }
167
168 return commit_creds(new);
169}
170
171/*
172 * Install a process keyring directly to a credentials struct.
173 *
174 * Returns -EEXIST if there was already a process keyring, 0 if one installed,
175 * and other value on any other error
176 */
177int install_process_keyring_to_cred(struct cred *new)
178{
179 struct key *keyring;
180
181 if (new->process_keyring)
182 return -EEXIST;
183
184 keyring = keyring_alloc("_pid", new->uid, new->gid, new,
185 KEY_POS_ALL | KEY_USR_VIEW,
186 KEY_ALLOC_QUOTA_OVERRUN,
187 NULL, NULL);
188 if (IS_ERR(keyring))
189 return PTR_ERR(keyring);
190
191 new->process_keyring = keyring;
192 return 0;
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->session_keyring)
234 flags = KEY_ALLOC_IN_QUOTA;
235
236 keyring = keyring_alloc("_ses", cred->uid, cred->gid, cred,
237 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
238 flags, NULL, NULL);
239 if (IS_ERR(keyring))
240 return PTR_ERR(keyring);
241 } else {
242 __key_get(keyring);
243 }
244
245 /* install the keyring */
246 old = cred->session_keyring;
247 rcu_assign_pointer(cred->session_keyring, keyring);
248
249 if (old)
250 key_put(old);
251
252 return 0;
253}
254
255/*
256 * Install a session keyring, discarding the old one. If a keyring is not
257 * supplied, an empty one is invented.
258 */
259static int install_session_keyring(struct key *keyring)
260{
261 struct cred *new;
262 int ret;
263
264 new = prepare_creds();
265 if (!new)
266 return -ENOMEM;
267
268 ret = install_session_keyring_to_cred(new, keyring);
269 if (ret < 0) {
270 abort_creds(new);
271 return ret;
272 }
273
274 return commit_creds(new);
275}
276
277/*
278 * Handle the fsuid changing.
279 */
280void key_fsuid_changed(struct task_struct *tsk)
281{
282 /* update the ownership of the thread keyring */
283 BUG_ON(!tsk->cred);
284 if (tsk->cred->thread_keyring) {
285 down_write(&tsk->cred->thread_keyring->sem);
286 tsk->cred->thread_keyring->uid = tsk->cred->fsuid;
287 up_write(&tsk->cred->thread_keyring->sem);
288 }
289}
290
291/*
292 * Handle the fsgid changing.
293 */
294void key_fsgid_changed(struct task_struct *tsk)
295{
296 /* update the ownership of the thread keyring */
297 BUG_ON(!tsk->cred);
298 if (tsk->cred->thread_keyring) {
299 down_write(&tsk->cred->thread_keyring->sem);
300 tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
301 up_write(&tsk->cred->thread_keyring->sem);
302 }
303}
304
305/*
306 * Search the process keyrings attached to the supplied cred for the first
307 * matching key.
308 *
309 * The search criteria are the type and the match function. The description is
310 * given to the match function as a parameter, but doesn't otherwise influence
311 * the search. Typically the match function will compare the description
312 * parameter to the key's description.
313 *
314 * This can only search keyrings that grant Search permission to the supplied
315 * credentials. Keyrings linked to searched keyrings will also be searched if
316 * they grant Search permission too. Keys can only be found if they grant
317 * Search permission to the credentials.
318 *
319 * Returns a pointer to the key with the key usage count incremented if
320 * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
321 * matched negative keys.
322 *
323 * In the case of a successful return, the possession attribute is set on the
324 * returned key reference.
325 */
326key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx)
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 (ctx->cred->thread_keyring) {
343 key_ref = keyring_search_aux(
344 make_key_ref(ctx->cred->thread_keyring, 1), ctx);
345 if (!IS_ERR(key_ref))
346 goto found;
347
348 switch (PTR_ERR(key_ref)) {
349 case -EAGAIN: /* no key */
350 case -ENOKEY: /* negative key */
351 ret = key_ref;
352 break;
353 default:
354 err = key_ref;
355 break;
356 }
357 }
358
359 /* search the process keyring second */
360 if (ctx->cred->process_keyring) {
361 key_ref = keyring_search_aux(
362 make_key_ref(ctx->cred->process_keyring, 1), ctx);
363 if (!IS_ERR(key_ref))
364 goto found;
365
366 switch (PTR_ERR(key_ref)) {
367 case -EAGAIN: /* no key */
368 if (ret)
369 break;
370 case -ENOKEY: /* negative key */
371 ret = key_ref;
372 break;
373 default:
374 err = key_ref;
375 break;
376 }
377 }
378
379 /* search the session keyring */
380 if (ctx->cred->session_keyring) {
381 rcu_read_lock();
382 key_ref = keyring_search_aux(
383 make_key_ref(rcu_dereference(ctx->cred->session_keyring), 1),
384 ctx);
385 rcu_read_unlock();
386
387 if (!IS_ERR(key_ref))
388 goto found;
389
390 switch (PTR_ERR(key_ref)) {
391 case -EAGAIN: /* no key */
392 if (ret)
393 break;
394 case -ENOKEY: /* negative key */
395 ret = key_ref;
396 break;
397 default:
398 err = key_ref;
399 break;
400 }
401 }
402 /* or search the user-session keyring */
403 else if (ctx->cred->user->session_keyring) {
404 key_ref = keyring_search_aux(
405 make_key_ref(ctx->cred->user->session_keyring, 1),
406 ctx);
407 if (!IS_ERR(key_ref))
408 goto found;
409
410 switch (PTR_ERR(key_ref)) {
411 case -EAGAIN: /* no key */
412 if (ret)
413 break;
414 case -ENOKEY: /* negative key */
415 ret = key_ref;
416 break;
417 default:
418 err = key_ref;
419 break;
420 }
421 }
422
423 /* no key - decide on the error we're going to go for */
424 key_ref = ret ? ret : err;
425
426found:
427 return key_ref;
428}
429
430/*
431 * Search the process keyrings attached to the supplied cred for the first
432 * matching key in the manner of search_my_process_keyrings(), but also search
433 * the keys attached to the assumed authorisation key using its credentials if
434 * one is available.
435 *
436 * Return same as search_my_process_keyrings().
437 */
438key_ref_t search_process_keyrings(struct keyring_search_context *ctx)
439{
440 struct request_key_auth *rka;
441 key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
442
443 might_sleep();
444
445 key_ref = search_my_process_keyrings(ctx);
446 if (!IS_ERR(key_ref))
447 goto found;
448 err = key_ref;
449
450 /* if this process has an instantiation authorisation key, then we also
451 * search the keyrings of the process mentioned there
452 * - we don't permit access to request_key auth keys via this method
453 */
454 if (ctx->cred->request_key_auth &&
455 ctx->cred == current_cred() &&
456 ctx->index_key.type != &key_type_request_key_auth
457 ) {
458 const struct cred *cred = ctx->cred;
459
460 /* defend against the auth key being revoked */
461 down_read(&cred->request_key_auth->sem);
462
463 if (key_validate(ctx->cred->request_key_auth) == 0) {
464 rka = ctx->cred->request_key_auth->payload.data[0];
465
466 ctx->cred = rka->cred;
467 key_ref = search_process_keyrings(ctx);
468 ctx->cred = cred;
469
470 up_read(&cred->request_key_auth->sem);
471
472 if (!IS_ERR(key_ref))
473 goto found;
474
475 ret = key_ref;
476 } else {
477 up_read(&cred->request_key_auth->sem);
478 }
479 }
480
481 /* no key - decide on the error we're going to go for */
482 if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
483 key_ref = ERR_PTR(-ENOKEY);
484 else if (err == ERR_PTR(-EACCES))
485 key_ref = ret;
486 else
487 key_ref = err;
488
489found:
490 return key_ref;
491}
492
493/*
494 * See if the key we're looking at is the target key.
495 */
496bool lookup_user_key_possessed(const struct key *key,
497 const struct key_match_data *match_data)
498{
499 return key == match_data->raw_data;
500}
501
502/*
503 * Look up a key ID given us by userspace with a given permissions mask to get
504 * the key it refers to.
505 *
506 * Flags can be passed to request that special keyrings be created if referred
507 * to directly, to permit partially constructed keys to be found and to skip
508 * validity and permission checks on the found key.
509 *
510 * Returns a pointer to the key with an incremented usage count if successful;
511 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
512 * to a key or the best found key was a negative key; -EKEYREVOKED or
513 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
514 * found key doesn't grant the requested permit or the LSM denied access to it;
515 * or -ENOMEM if a special keyring couldn't be created.
516 *
517 * In the case of a successful return, the possession attribute is set on the
518 * returned key reference.
519 */
520key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
521 key_perm_t perm)
522{
523 struct keyring_search_context ctx = {
524 .match_data.cmp = lookup_user_key_possessed,
525 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
526 .flags = KEYRING_SEARCH_NO_STATE_CHECK,
527 };
528 struct request_key_auth *rka;
529 struct key *key;
530 key_ref_t key_ref, skey_ref;
531 int ret;
532
533try_again:
534 ctx.cred = get_current_cred();
535 key_ref = ERR_PTR(-ENOKEY);
536
537 switch (id) {
538 case KEY_SPEC_THREAD_KEYRING:
539 if (!ctx.cred->thread_keyring) {
540 if (!(lflags & KEY_LOOKUP_CREATE))
541 goto error;
542
543 ret = install_thread_keyring();
544 if (ret < 0) {
545 key_ref = ERR_PTR(ret);
546 goto error;
547 }
548 goto reget_creds;
549 }
550
551 key = ctx.cred->thread_keyring;
552 __key_get(key);
553 key_ref = make_key_ref(key, 1);
554 break;
555
556 case KEY_SPEC_PROCESS_KEYRING:
557 if (!ctx.cred->process_keyring) {
558 if (!(lflags & KEY_LOOKUP_CREATE))
559 goto error;
560
561 ret = install_process_keyring();
562 if (ret < 0) {
563 key_ref = ERR_PTR(ret);
564 goto error;
565 }
566 goto reget_creds;
567 }
568
569 key = ctx.cred->process_keyring;
570 __key_get(key);
571 key_ref = make_key_ref(key, 1);
572 break;
573
574 case KEY_SPEC_SESSION_KEYRING:
575 if (!ctx.cred->session_keyring) {
576 /* always install a session keyring upon access if one
577 * doesn't exist yet */
578 ret = install_user_keyrings();
579 if (ret < 0)
580 goto error;
581 if (lflags & KEY_LOOKUP_CREATE)
582 ret = join_session_keyring(NULL);
583 else
584 ret = install_session_keyring(
585 ctx.cred->user->session_keyring);
586
587 if (ret < 0)
588 goto error;
589 goto reget_creds;
590 } else if (ctx.cred->session_keyring ==
591 ctx.cred->user->session_keyring &&
592 lflags & KEY_LOOKUP_CREATE) {
593 ret = join_session_keyring(NULL);
594 if (ret < 0)
595 goto error;
596 goto reget_creds;
597 }
598
599 rcu_read_lock();
600 key = rcu_dereference(ctx.cred->session_keyring);
601 __key_get(key);
602 rcu_read_unlock();
603 key_ref = make_key_ref(key, 1);
604 break;
605
606 case KEY_SPEC_USER_KEYRING:
607 if (!ctx.cred->user->uid_keyring) {
608 ret = install_user_keyrings();
609 if (ret < 0)
610 goto error;
611 }
612
613 key = ctx.cred->user->uid_keyring;
614 __key_get(key);
615 key_ref = make_key_ref(key, 1);
616 break;
617
618 case KEY_SPEC_USER_SESSION_KEYRING:
619 if (!ctx.cred->user->session_keyring) {
620 ret = install_user_keyrings();
621 if (ret < 0)
622 goto error;
623 }
624
625 key = ctx.cred->user->session_keyring;
626 __key_get(key);
627 key_ref = make_key_ref(key, 1);
628 break;
629
630 case KEY_SPEC_GROUP_KEYRING:
631 /* group keyrings are not yet supported */
632 key_ref = ERR_PTR(-EINVAL);
633 goto error;
634
635 case KEY_SPEC_REQKEY_AUTH_KEY:
636 key = ctx.cred->request_key_auth;
637 if (!key)
638 goto error;
639
640 __key_get(key);
641 key_ref = make_key_ref(key, 1);
642 break;
643
644 case KEY_SPEC_REQUESTOR_KEYRING:
645 if (!ctx.cred->request_key_auth)
646 goto error;
647
648 down_read(&ctx.cred->request_key_auth->sem);
649 if (test_bit(KEY_FLAG_REVOKED,
650 &ctx.cred->request_key_auth->flags)) {
651 key_ref = ERR_PTR(-EKEYREVOKED);
652 key = NULL;
653 } else {
654 rka = ctx.cred->request_key_auth->payload.data[0];
655 key = rka->dest_keyring;
656 __key_get(key);
657 }
658 up_read(&ctx.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 ctx.index_key.type = key->type;
679 ctx.index_key.description = key->description;
680 ctx.index_key.desc_len = strlen(key->description);
681 ctx.match_data.raw_data = key;
682 kdebug("check possessed");
683 skey_ref = search_process_keyrings(&ctx);
684 kdebug("possessed=%p", skey_ref);
685
686 if (!IS_ERR(skey_ref)) {
687 key_put(key);
688 key_ref = skey_ref;
689 }
690
691 break;
692 }
693
694 /* unlink does not use the nominated key in any way, so can skip all
695 * the permission checks as it is only concerned with the keyring */
696 if (lflags & KEY_LOOKUP_FOR_UNLINK) {
697 ret = 0;
698 goto error;
699 }
700
701 if (!(lflags & KEY_LOOKUP_PARTIAL)) {
702 ret = wait_for_key_construction(key, true);
703 switch (ret) {
704 case -ERESTARTSYS:
705 goto invalid_key;
706 default:
707 if (perm)
708 goto invalid_key;
709 case 0:
710 break;
711 }
712 } else if (perm) {
713 ret = key_validate(key);
714 if (ret < 0)
715 goto invalid_key;
716 }
717
718 ret = -EIO;
719 if (!(lflags & KEY_LOOKUP_PARTIAL) &&
720 !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
721 goto invalid_key;
722
723 /* check the permissions */
724 ret = key_task_permission(key_ref, ctx.cred, perm);
725 if (ret < 0)
726 goto invalid_key;
727
728 key->last_used_at = current_kernel_time().tv_sec;
729
730error:
731 put_cred(ctx.cred);
732 return key_ref;
733
734invalid_key:
735 key_ref_put(key_ref);
736 key_ref = ERR_PTR(ret);
737 goto error;
738
739 /* if we attempted to install a keyring, then it may have caused new
740 * creds to be installed */
741reget_creds:
742 put_cred(ctx.cred);
743 goto try_again;
744}
745
746/*
747 * Join the named keyring as the session keyring if possible else attempt to
748 * create a new one of that name and join that.
749 *
750 * If the name is NULL, an empty anonymous keyring will be installed as the
751 * session keyring.
752 *
753 * Named session keyrings are joined with a semaphore held to prevent the
754 * keyrings from going away whilst the attempt is made to going them and also
755 * to prevent a race in creating compatible session keyrings.
756 */
757long join_session_keyring(const char *name)
758{
759 const struct cred *old;
760 struct cred *new;
761 struct key *keyring;
762 long ret, serial;
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->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(
790 name, old->uid, old->gid, old,
791 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_LINK,
792 KEY_ALLOC_IN_QUOTA, NULL, NULL);
793 if (IS_ERR(keyring)) {
794 ret = PTR_ERR(keyring);
795 goto error2;
796 }
797 } else if (IS_ERR(keyring)) {
798 ret = PTR_ERR(keyring);
799 goto error2;
800 } else if (keyring == new->session_keyring) {
801 key_put(keyring);
802 ret = 0;
803 goto error2;
804 }
805
806 /* we've got a keyring - now to install it */
807 ret = install_session_keyring_to_cred(new, keyring);
808 if (ret < 0)
809 goto error2;
810
811 commit_creds(new);
812 mutex_unlock(&key_session_mutex);
813
814 ret = keyring->serial;
815 key_put(keyring);
816okay:
817 return ret;
818
819error2:
820 mutex_unlock(&key_session_mutex);
821error:
822 abort_creds(new);
823 return ret;
824}
825
826/*
827 * Replace a process's session keyring on behalf of one of its children when
828 * the target process is about to resume userspace execution.
829 */
830void key_change_session_keyring(struct callback_head *twork)
831{
832 const struct cred *old = current_cred();
833 struct cred *new = container_of(twork, struct cred, rcu);
834
835 if (unlikely(current->flags & PF_EXITING)) {
836 put_cred(new);
837 return;
838 }
839
840 new-> uid = old-> uid;
841 new-> euid = old-> euid;
842 new-> suid = old-> suid;
843 new->fsuid = old->fsuid;
844 new-> gid = old-> gid;
845 new-> egid = old-> egid;
846 new-> sgid = old-> sgid;
847 new->fsgid = old->fsgid;
848 new->user = get_uid(old->user);
849 new->user_ns = get_user_ns(old->user_ns);
850 new->group_info = get_group_info(old->group_info);
851
852 new->securebits = old->securebits;
853 new->cap_inheritable = old->cap_inheritable;
854 new->cap_permitted = old->cap_permitted;
855 new->cap_effective = old->cap_effective;
856 new->cap_ambient = old->cap_ambient;
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->process_keyring = key_get(old->process_keyring);
862
863 security_transfer_creds(new, old);
864
865 commit_creds(new);
866}
867
868/*
869 * Make sure that root's user and user-session keyrings exist.
870 */
871static int __init init_root_keyring(void)
872{
873 return install_user_keyrings();
874}
875
876late_initcall(init_root_keyring);