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_UID_KEYRING |
80 KEY_ALLOC_IN_QUOTA,
81 NULL);
82 if (IS_ERR(uid_keyring)) {
83 ret = PTR_ERR(uid_keyring);
84 goto error;
85 }
86 }
87
88 /* get a default session keyring (which might also exist
89 * already) */
90 sprintf(buf, "_uid_ses.%u", uid);
91
92 session_keyring = find_keyring_by_name(buf, true);
93 if (IS_ERR(session_keyring)) {
94 session_keyring =
95 keyring_alloc(buf, user->uid, INVALID_GID,
96 cred, user_keyring_perm,
97 KEY_ALLOC_UID_KEYRING |
98 KEY_ALLOC_IN_QUOTA,
99 NULL);
100 if (IS_ERR(session_keyring)) {
101 ret = PTR_ERR(session_keyring);
102 goto error_release;
103 }
104
105 /* we install a link from the user session keyring to
106 * the user keyring */
107 ret = key_link(session_keyring, uid_keyring);
108 if (ret < 0)
109 goto error_release_both;
110 }
111
112 /* install the keyrings */
113 user->uid_keyring = uid_keyring;
114 user->session_keyring = session_keyring;
115 }
116
117 mutex_unlock(&key_user_keyring_mutex);
118 kleave(" = 0");
119 return 0;
120
121 error_release_both:
122 key_put(session_keyring);
123 error_release:
124 key_put(uid_keyring);
125 error:
126 mutex_unlock(&key_user_keyring_mutex);
127 kleave(" = %d", ret);
128 return ret;
129 }
130
131 /*
132 * Install a thread keyring to the given credentials struct if it didn't have
133 * one already. This is allowed to overrun the quota.
134 *
135 * Return: 0 if a thread keyring is now present; -errno on failure.
136 */
install_thread_keyring_to_cred(struct cred * new)137 int install_thread_keyring_to_cred(struct cred *new)
138 {
139 struct key *keyring;
140
141 if (new->thread_keyring)
142 return 0;
143
144 keyring = keyring_alloc("_tid", new->uid, new->gid, new,
145 KEY_POS_ALL | KEY_USR_VIEW,
146 KEY_ALLOC_QUOTA_OVERRUN, NULL);
147 if (IS_ERR(keyring))
148 return PTR_ERR(keyring);
149
150 new->thread_keyring = keyring;
151 return 0;
152 }
153
154 /*
155 * Install a thread keyring to the current task if it didn't have one already.
156 *
157 * Return: 0 if a thread keyring is now present; -errno on failure.
158 */
install_thread_keyring(void)159 static int install_thread_keyring(void)
160 {
161 struct cred *new;
162 int ret;
163
164 new = prepare_creds();
165 if (!new)
166 return -ENOMEM;
167
168 ret = install_thread_keyring_to_cred(new);
169 if (ret < 0) {
170 abort_creds(new);
171 return ret;
172 }
173
174 return commit_creds(new);
175 }
176
177 /*
178 * Install a process keyring to the given credentials struct if it didn't have
179 * one already. This is allowed to overrun the quota.
180 *
181 * Return: 0 if a process keyring is now present; -errno on failure.
182 */
install_process_keyring_to_cred(struct cred * new)183 int install_process_keyring_to_cred(struct cred *new)
184 {
185 struct key *keyring;
186
187 if (new->process_keyring)
188 return 0;
189
190 keyring = keyring_alloc("_pid", new->uid, new->gid, new,
191 KEY_POS_ALL | KEY_USR_VIEW,
192 KEY_ALLOC_QUOTA_OVERRUN, NULL);
193 if (IS_ERR(keyring))
194 return PTR_ERR(keyring);
195
196 new->process_keyring = keyring;
197 return 0;
198 }
199
200 /*
201 * Install a process keyring to the current task if it didn't have one already.
202 *
203 * Return: 0 if a process keyring is now present; -errno on failure.
204 */
install_process_keyring(void)205 static int install_process_keyring(void)
206 {
207 struct cred *new;
208 int ret;
209
210 new = prepare_creds();
211 if (!new)
212 return -ENOMEM;
213
214 ret = install_process_keyring_to_cred(new);
215 if (ret < 0) {
216 abort_creds(new);
217 return ret;
218 }
219
220 return commit_creds(new);
221 }
222
223 /*
224 * Install the given keyring as the session keyring of the given credentials
225 * struct, replacing the existing one if any. If the given keyring is NULL,
226 * then install a new anonymous session keyring.
227 *
228 * Return: 0 on success; -errno on failure.
229 */
install_session_keyring_to_cred(struct cred * cred,struct key * keyring)230 int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
231 {
232 unsigned long flags;
233 struct key *old;
234
235 might_sleep();
236
237 /* create an empty session keyring */
238 if (!keyring) {
239 flags = KEY_ALLOC_QUOTA_OVERRUN;
240 if (cred->session_keyring)
241 flags = KEY_ALLOC_IN_QUOTA;
242
243 keyring = keyring_alloc("_ses", cred->uid, cred->gid, cred,
244 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
245 flags, NULL);
246 if (IS_ERR(keyring))
247 return PTR_ERR(keyring);
248 } else {
249 __key_get(keyring);
250 }
251
252 /* install the keyring */
253 old = cred->session_keyring;
254 rcu_assign_pointer(cred->session_keyring, keyring);
255
256 if (old)
257 key_put(old);
258
259 return 0;
260 }
261
262 /*
263 * Install the given keyring as the session keyring of the current task,
264 * replacing the existing one if any. If the given keyring is NULL, then
265 * install a new anonymous session keyring.
266 *
267 * Return: 0 on success; -errno on failure.
268 */
install_session_keyring(struct key * keyring)269 static int install_session_keyring(struct key *keyring)
270 {
271 struct cred *new;
272 int ret;
273
274 new = prepare_creds();
275 if (!new)
276 return -ENOMEM;
277
278 ret = install_session_keyring_to_cred(new, keyring);
279 if (ret < 0) {
280 abort_creds(new);
281 return ret;
282 }
283
284 return commit_creds(new);
285 }
286
287 /*
288 * Handle the fsuid changing.
289 */
key_fsuid_changed(struct task_struct * tsk)290 void key_fsuid_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->uid = tsk->cred->fsuid;
297 up_write(&tsk->cred->thread_keyring->sem);
298 }
299 }
300
301 /*
302 * Handle the fsgid changing.
303 */
key_fsgid_changed(struct task_struct * tsk)304 void key_fsgid_changed(struct task_struct *tsk)
305 {
306 /* update the ownership of the thread keyring */
307 BUG_ON(!tsk->cred);
308 if (tsk->cred->thread_keyring) {
309 down_write(&tsk->cred->thread_keyring->sem);
310 tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
311 up_write(&tsk->cred->thread_keyring->sem);
312 }
313 }
314
315 /*
316 * Search the process keyrings attached to the supplied cred for the first
317 * matching key.
318 *
319 * The search criteria are the type and the match function. The description is
320 * given to the match function as a parameter, but doesn't otherwise influence
321 * the search. Typically the match function will compare the description
322 * parameter to the key's description.
323 *
324 * This can only search keyrings that grant Search permission to the supplied
325 * credentials. Keyrings linked to searched keyrings will also be searched if
326 * they grant Search permission too. Keys can only be found if they grant
327 * Search permission to the credentials.
328 *
329 * Returns a pointer to the key with the key usage count incremented if
330 * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
331 * matched negative keys.
332 *
333 * In the case of a successful return, the possession attribute is set on the
334 * returned key reference.
335 */
search_my_process_keyrings(struct keyring_search_context * ctx)336 key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx)
337 {
338 key_ref_t key_ref, ret, err;
339
340 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
341 * searchable, but we failed to find a key or we found a negative key;
342 * otherwise we want to return a sample error (probably -EACCES) if
343 * none of the keyrings were searchable
344 *
345 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
346 */
347 key_ref = NULL;
348 ret = NULL;
349 err = ERR_PTR(-EAGAIN);
350
351 /* search the thread keyring first */
352 if (ctx->cred->thread_keyring) {
353 key_ref = keyring_search_aux(
354 make_key_ref(ctx->cred->thread_keyring, 1), ctx);
355 if (!IS_ERR(key_ref))
356 goto found;
357
358 switch (PTR_ERR(key_ref)) {
359 case -EAGAIN: /* no key */
360 case -ENOKEY: /* negative key */
361 ret = key_ref;
362 break;
363 default:
364 err = key_ref;
365 break;
366 }
367 }
368
369 /* search the process keyring second */
370 if (ctx->cred->process_keyring) {
371 key_ref = keyring_search_aux(
372 make_key_ref(ctx->cred->process_keyring, 1), ctx);
373 if (!IS_ERR(key_ref))
374 goto found;
375
376 switch (PTR_ERR(key_ref)) {
377 case -EAGAIN: /* no key */
378 if (ret)
379 break;
380 case -ENOKEY: /* negative key */
381 ret = key_ref;
382 break;
383 default:
384 err = key_ref;
385 break;
386 }
387 }
388
389 /* search the session keyring */
390 if (ctx->cred->session_keyring) {
391 rcu_read_lock();
392 key_ref = keyring_search_aux(
393 make_key_ref(rcu_dereference(ctx->cred->session_keyring), 1),
394 ctx);
395 rcu_read_unlock();
396
397 if (!IS_ERR(key_ref))
398 goto found;
399
400 switch (PTR_ERR(key_ref)) {
401 case -EAGAIN: /* no key */
402 if (ret)
403 break;
404 case -ENOKEY: /* negative key */
405 ret = key_ref;
406 break;
407 default:
408 err = key_ref;
409 break;
410 }
411 }
412 /* or search the user-session keyring */
413 else if (ctx->cred->user->session_keyring) {
414 key_ref = keyring_search_aux(
415 make_key_ref(ctx->cred->user->session_keyring, 1),
416 ctx);
417 if (!IS_ERR(key_ref))
418 goto found;
419
420 switch (PTR_ERR(key_ref)) {
421 case -EAGAIN: /* no key */
422 if (ret)
423 break;
424 case -ENOKEY: /* negative key */
425 ret = key_ref;
426 break;
427 default:
428 err = key_ref;
429 break;
430 }
431 }
432
433 /* no key - decide on the error we're going to go for */
434 key_ref = ret ? ret : err;
435
436 found:
437 return key_ref;
438 }
439
440 /*
441 * Search the process keyrings attached to the supplied cred for the first
442 * matching key in the manner of search_my_process_keyrings(), but also search
443 * the keys attached to the assumed authorisation key using its credentials if
444 * one is available.
445 *
446 * Return same as search_my_process_keyrings().
447 */
search_process_keyrings(struct keyring_search_context * ctx)448 key_ref_t search_process_keyrings(struct keyring_search_context *ctx)
449 {
450 struct request_key_auth *rka;
451 key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
452
453 might_sleep();
454
455 key_ref = search_my_process_keyrings(ctx);
456 if (!IS_ERR(key_ref))
457 goto found;
458 err = key_ref;
459
460 /* if this process has an instantiation authorisation key, then we also
461 * search the keyrings of the process mentioned there
462 * - we don't permit access to request_key auth keys via this method
463 */
464 if (ctx->cred->request_key_auth &&
465 ctx->cred == current_cred() &&
466 ctx->index_key.type != &key_type_request_key_auth
467 ) {
468 const struct cred *cred = ctx->cred;
469
470 /* defend against the auth key being revoked */
471 down_read(&cred->request_key_auth->sem);
472
473 if (key_validate(ctx->cred->request_key_auth) == 0) {
474 rka = ctx->cred->request_key_auth->payload.data;
475
476 ctx->cred = rka->cred;
477 key_ref = search_process_keyrings(ctx);
478 ctx->cred = cred;
479
480 up_read(&cred->request_key_auth->sem);
481
482 if (!IS_ERR(key_ref))
483 goto found;
484
485 ret = key_ref;
486 } else {
487 up_read(&cred->request_key_auth->sem);
488 }
489 }
490
491 /* no key - decide on the error we're going to go for */
492 if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
493 key_ref = ERR_PTR(-ENOKEY);
494 else if (err == ERR_PTR(-EACCES))
495 key_ref = ret;
496 else
497 key_ref = err;
498
499 found:
500 return key_ref;
501 }
502
503 /*
504 * See if the key we're looking at is the target key.
505 */
lookup_user_key_possessed(const struct key * key,const struct key_match_data * match_data)506 bool lookup_user_key_possessed(const struct key *key,
507 const struct key_match_data *match_data)
508 {
509 return key == match_data->raw_data;
510 }
511
512 /*
513 * Look up a key ID given us by userspace with a given permissions mask to get
514 * the key it refers to.
515 *
516 * Flags can be passed to request that special keyrings be created if referred
517 * to directly, to permit partially constructed keys to be found and to skip
518 * validity and permission checks on the found key.
519 *
520 * Returns a pointer to the key with an incremented usage count if successful;
521 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
522 * to a key or the best found key was a negative key; -EKEYREVOKED or
523 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
524 * found key doesn't grant the requested permit or the LSM denied access to it;
525 * or -ENOMEM if a special keyring couldn't be created.
526 *
527 * In the case of a successful return, the possession attribute is set on the
528 * returned key reference.
529 */
lookup_user_key(key_serial_t id,unsigned long lflags,key_perm_t perm)530 key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
531 key_perm_t perm)
532 {
533 struct keyring_search_context ctx = {
534 .match_data.cmp = lookup_user_key_possessed,
535 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
536 .flags = KEYRING_SEARCH_NO_STATE_CHECK,
537 };
538 struct request_key_auth *rka;
539 struct key *key;
540 key_ref_t key_ref, skey_ref;
541 int ret;
542
543 try_again:
544 ctx.cred = get_current_cred();
545 key_ref = ERR_PTR(-ENOKEY);
546
547 switch (id) {
548 case KEY_SPEC_THREAD_KEYRING:
549 if (!ctx.cred->thread_keyring) {
550 if (!(lflags & KEY_LOOKUP_CREATE))
551 goto error;
552
553 ret = install_thread_keyring();
554 if (ret < 0) {
555 key_ref = ERR_PTR(ret);
556 goto error;
557 }
558 goto reget_creds;
559 }
560
561 key = ctx.cred->thread_keyring;
562 __key_get(key);
563 key_ref = make_key_ref(key, 1);
564 break;
565
566 case KEY_SPEC_PROCESS_KEYRING:
567 if (!ctx.cred->process_keyring) {
568 if (!(lflags & KEY_LOOKUP_CREATE))
569 goto error;
570
571 ret = install_process_keyring();
572 if (ret < 0) {
573 key_ref = ERR_PTR(ret);
574 goto error;
575 }
576 goto reget_creds;
577 }
578
579 key = ctx.cred->process_keyring;
580 __key_get(key);
581 key_ref = make_key_ref(key, 1);
582 break;
583
584 case KEY_SPEC_SESSION_KEYRING:
585 if (!ctx.cred->session_keyring) {
586 /* always install a session keyring upon access if one
587 * doesn't exist yet */
588 ret = install_user_keyrings();
589 if (ret < 0)
590 goto error;
591 if (lflags & KEY_LOOKUP_CREATE)
592 ret = join_session_keyring(NULL);
593 else
594 ret = install_session_keyring(
595 ctx.cred->user->session_keyring);
596
597 if (ret < 0)
598 goto error;
599 goto reget_creds;
600 } else if (ctx.cred->session_keyring ==
601 ctx.cred->user->session_keyring &&
602 lflags & KEY_LOOKUP_CREATE) {
603 ret = join_session_keyring(NULL);
604 if (ret < 0)
605 goto error;
606 goto reget_creds;
607 }
608
609 rcu_read_lock();
610 key = rcu_dereference(ctx.cred->session_keyring);
611 __key_get(key);
612 rcu_read_unlock();
613 key_ref = make_key_ref(key, 1);
614 break;
615
616 case KEY_SPEC_USER_KEYRING:
617 if (!ctx.cred->user->uid_keyring) {
618 ret = install_user_keyrings();
619 if (ret < 0)
620 goto error;
621 }
622
623 key = ctx.cred->user->uid_keyring;
624 __key_get(key);
625 key_ref = make_key_ref(key, 1);
626 break;
627
628 case KEY_SPEC_USER_SESSION_KEYRING:
629 if (!ctx.cred->user->session_keyring) {
630 ret = install_user_keyrings();
631 if (ret < 0)
632 goto error;
633 }
634
635 key = ctx.cred->user->session_keyring;
636 __key_get(key);
637 key_ref = make_key_ref(key, 1);
638 break;
639
640 case KEY_SPEC_GROUP_KEYRING:
641 /* group keyrings are not yet supported */
642 key_ref = ERR_PTR(-EINVAL);
643 goto error;
644
645 case KEY_SPEC_REQKEY_AUTH_KEY:
646 key = ctx.cred->request_key_auth;
647 if (!key)
648 goto error;
649
650 __key_get(key);
651 key_ref = make_key_ref(key, 1);
652 break;
653
654 case KEY_SPEC_REQUESTOR_KEYRING:
655 if (!ctx.cred->request_key_auth)
656 goto error;
657
658 down_read(&ctx.cred->request_key_auth->sem);
659 if (test_bit(KEY_FLAG_REVOKED,
660 &ctx.cred->request_key_auth->flags)) {
661 key_ref = ERR_PTR(-EKEYREVOKED);
662 key = NULL;
663 } else {
664 rka = ctx.cred->request_key_auth->payload.data;
665 key = rka->dest_keyring;
666 __key_get(key);
667 }
668 up_read(&ctx.cred->request_key_auth->sem);
669 if (!key)
670 goto error;
671 key_ref = make_key_ref(key, 1);
672 break;
673
674 default:
675 key_ref = ERR_PTR(-EINVAL);
676 if (id < 1)
677 goto error;
678
679 key = key_lookup(id);
680 if (IS_ERR(key)) {
681 key_ref = ERR_CAST(key);
682 goto error;
683 }
684
685 key_ref = make_key_ref(key, 0);
686
687 /* check to see if we possess the key */
688 ctx.index_key.type = key->type;
689 ctx.index_key.description = key->description;
690 ctx.index_key.desc_len = strlen(key->description);
691 ctx.match_data.raw_data = key;
692 kdebug("check possessed");
693 skey_ref = search_process_keyrings(&ctx);
694 kdebug("possessed=%p", skey_ref);
695
696 if (!IS_ERR(skey_ref)) {
697 key_put(key);
698 key_ref = skey_ref;
699 }
700
701 break;
702 }
703
704 /* unlink does not use the nominated key in any way, so can skip all
705 * the permission checks as it is only concerned with the keyring */
706 if (lflags & KEY_LOOKUP_FOR_UNLINK) {
707 ret = 0;
708 goto error;
709 }
710
711 if (!(lflags & KEY_LOOKUP_PARTIAL)) {
712 ret = wait_for_key_construction(key, true);
713 switch (ret) {
714 case -ERESTARTSYS:
715 goto invalid_key;
716 default:
717 if (perm)
718 goto invalid_key;
719 case 0:
720 break;
721 }
722 } else if (perm) {
723 ret = key_validate(key);
724 if (ret < 0)
725 goto invalid_key;
726 }
727
728 ret = -EIO;
729 if (!(lflags & KEY_LOOKUP_PARTIAL) &&
730 !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
731 goto invalid_key;
732
733 /* check the permissions */
734 ret = key_task_permission(key_ref, ctx.cred, perm);
735 if (ret < 0)
736 goto invalid_key;
737
738 key->last_used_at = current_kernel_time().tv_sec;
739
740 error:
741 put_cred(ctx.cred);
742 return key_ref;
743
744 invalid_key:
745 key_ref_put(key_ref);
746 key_ref = ERR_PTR(ret);
747 goto error;
748
749 /* if we attempted to install a keyring, then it may have caused new
750 * creds to be installed */
751 reget_creds:
752 put_cred(ctx.cred);
753 goto try_again;
754 }
755
756 /*
757 * Join the named keyring as the session keyring if possible else attempt to
758 * create a new one of that name and join that.
759 *
760 * If the name is NULL, an empty anonymous keyring will be installed as the
761 * session keyring.
762 *
763 * Named session keyrings are joined with a semaphore held to prevent the
764 * keyrings from going away whilst the attempt is made to going them and also
765 * to prevent a race in creating compatible session keyrings.
766 */
join_session_keyring(const char * name)767 long join_session_keyring(const char *name)
768 {
769 const struct cred *old;
770 struct cred *new;
771 struct key *keyring;
772 long ret, serial;
773
774 new = prepare_creds();
775 if (!new)
776 return -ENOMEM;
777 old = current_cred();
778
779 /* if no name is provided, install an anonymous keyring */
780 if (!name) {
781 ret = install_session_keyring_to_cred(new, NULL);
782 if (ret < 0)
783 goto error;
784
785 serial = new->session_keyring->serial;
786 ret = commit_creds(new);
787 if (ret == 0)
788 ret = serial;
789 goto okay;
790 }
791
792 /* allow the user to join or create a named keyring */
793 mutex_lock(&key_session_mutex);
794
795 /* look for an existing keyring of this name */
796 keyring = find_keyring_by_name(name, false);
797 if (PTR_ERR(keyring) == -ENOKEY) {
798 /* not found - try and create a new one */
799 keyring = keyring_alloc(
800 name, old->uid, old->gid, old,
801 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_LINK,
802 KEY_ALLOC_IN_QUOTA, NULL);
803 if (IS_ERR(keyring)) {
804 ret = PTR_ERR(keyring);
805 goto error2;
806 }
807 } else if (IS_ERR(keyring)) {
808 ret = PTR_ERR(keyring);
809 goto error2;
810 } else if (keyring == new->session_keyring) {
811 key_put(keyring);
812 ret = 0;
813 goto error2;
814 }
815
816 /* we've got a keyring - now to install it */
817 ret = install_session_keyring_to_cred(new, keyring);
818 if (ret < 0)
819 goto error2;
820
821 commit_creds(new);
822 mutex_unlock(&key_session_mutex);
823
824 ret = keyring->serial;
825 key_put(keyring);
826 okay:
827 return ret;
828
829 error2:
830 mutex_unlock(&key_session_mutex);
831 error:
832 abort_creds(new);
833 return ret;
834 }
835
836 /*
837 * Replace a process's session keyring on behalf of one of its children when
838 * the target process is about to resume userspace execution.
839 */
key_change_session_keyring(struct callback_head * twork)840 void key_change_session_keyring(struct callback_head *twork)
841 {
842 const struct cred *old = current_cred();
843 struct cred *new = container_of(twork, struct cred, rcu);
844
845 if (unlikely(current->flags & PF_EXITING)) {
846 put_cred(new);
847 return;
848 }
849
850 new-> uid = old-> uid;
851 new-> euid = old-> euid;
852 new-> suid = old-> suid;
853 new->fsuid = old->fsuid;
854 new-> gid = old-> gid;
855 new-> egid = old-> egid;
856 new-> sgid = old-> sgid;
857 new->fsgid = old->fsgid;
858 new->user = get_uid(old->user);
859 new->user_ns = get_user_ns(old->user_ns);
860 new->group_info = get_group_info(old->group_info);
861
862 new->securebits = old->securebits;
863 new->cap_inheritable = old->cap_inheritable;
864 new->cap_permitted = old->cap_permitted;
865 new->cap_effective = old->cap_effective;
866 new->cap_ambient = old->cap_ambient;
867 new->cap_bset = old->cap_bset;
868
869 new->jit_keyring = old->jit_keyring;
870 new->thread_keyring = key_get(old->thread_keyring);
871 new->process_keyring = key_get(old->process_keyring);
872
873 security_transfer_creds(new, old);
874
875 commit_creds(new);
876 }
877
878 /*
879 * Make sure that root's user and user-session keyrings exist.
880 */
init_root_keyring(void)881 static int __init init_root_keyring(void)
882 {
883 return install_user_keyrings();
884 }
885
886 late_initcall(init_root_keyring);
887