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/sched/user.h>
16 #include <linux/keyctl.h>
17 #include <linux/fs.h>
18 #include <linux/err.h>
19 #include <linux/mutex.h>
20 #include <linux/security.h>
21 #include <linux/user_namespace.h>
22 #include <linux/uaccess.h>
23 #include <keys/request_key_auth-type.h>
24 #include "internal.h"
25
26 /* Session keyring create vs join semaphore */
27 static DEFINE_MUTEX(key_session_mutex);
28
29 /* User keyring creation semaphore */
30 static DEFINE_MUTEX(key_user_keyring_mutex);
31
32 /* The root user's tracking struct */
33 struct key_user root_key_user = {
34 .usage = REFCOUNT_INIT(3),
35 .cons_lock = __MUTEX_INITIALIZER(root_key_user.cons_lock),
36 .lock = __SPIN_LOCK_UNLOCKED(root_key_user.lock),
37 .nkeys = ATOMIC_INIT(2),
38 .nikeys = ATOMIC_INIT(2),
39 .uid = GLOBAL_ROOT_UID,
40 };
41
42 /*
43 * Install the user and user session keyrings for the current process's UID.
44 */
install_user_keyrings(void)45 int install_user_keyrings(void)
46 {
47 struct user_struct *user;
48 const struct cred *cred;
49 struct key *uid_keyring, *session_keyring;
50 key_perm_t user_keyring_perm;
51 char buf[20];
52 int ret;
53 uid_t uid;
54
55 user_keyring_perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL;
56 cred = current_cred();
57 user = cred->user;
58 uid = from_kuid(cred->user_ns, user->uid);
59
60 kenter("%p{%u}", user, uid);
61
62 if (user->uid_keyring && user->session_keyring) {
63 kleave(" = 0 [exist]");
64 return 0;
65 }
66
67 mutex_lock(&key_user_keyring_mutex);
68 ret = 0;
69
70 if (!user->uid_keyring) {
71 /* get the UID-specific keyring
72 * - there may be one in existence already as it may have been
73 * pinned by a session, but the user_struct pointing to it
74 * may have been destroyed by setuid */
75 sprintf(buf, "_uid.%u", uid);
76
77 uid_keyring = find_keyring_by_name(buf, true);
78 if (IS_ERR(uid_keyring)) {
79 uid_keyring = keyring_alloc(buf, user->uid, INVALID_GID,
80 cred, user_keyring_perm,
81 KEY_ALLOC_UID_KEYRING |
82 KEY_ALLOC_IN_QUOTA,
83 NULL, NULL);
84 if (IS_ERR(uid_keyring)) {
85 ret = PTR_ERR(uid_keyring);
86 goto error;
87 }
88 }
89
90 /* get a default session keyring (which might also exist
91 * already) */
92 sprintf(buf, "_uid_ses.%u", uid);
93
94 session_keyring = find_keyring_by_name(buf, true);
95 if (IS_ERR(session_keyring)) {
96 session_keyring =
97 keyring_alloc(buf, user->uid, INVALID_GID,
98 cred, user_keyring_perm,
99 KEY_ALLOC_UID_KEYRING |
100 KEY_ALLOC_IN_QUOTA,
101 NULL, NULL);
102 if (IS_ERR(session_keyring)) {
103 ret = PTR_ERR(session_keyring);
104 goto error_release;
105 }
106
107 /* we install a link from the user session keyring to
108 * the user keyring */
109 ret = key_link(session_keyring, uid_keyring);
110 if (ret < 0)
111 goto error_release_both;
112 }
113
114 /* install the keyrings */
115 user->uid_keyring = uid_keyring;
116 user->session_keyring = session_keyring;
117 }
118
119 mutex_unlock(&key_user_keyring_mutex);
120 kleave(" = 0");
121 return 0;
122
123 error_release_both:
124 key_put(session_keyring);
125 error_release:
126 key_put(uid_keyring);
127 error:
128 mutex_unlock(&key_user_keyring_mutex);
129 kleave(" = %d", ret);
130 return ret;
131 }
132
133 /*
134 * Install a thread keyring to the given credentials struct if it didn't have
135 * one already. This is allowed to overrun the quota.
136 *
137 * Return: 0 if a thread keyring is now present; -errno on failure.
138 */
install_thread_keyring_to_cred(struct cred * new)139 int install_thread_keyring_to_cred(struct cred *new)
140 {
141 struct key *keyring;
142
143 if (new->thread_keyring)
144 return 0;
145
146 keyring = keyring_alloc("_tid", new->uid, new->gid, new,
147 KEY_POS_ALL | KEY_USR_VIEW,
148 KEY_ALLOC_QUOTA_OVERRUN,
149 NULL, NULL);
150 if (IS_ERR(keyring))
151 return PTR_ERR(keyring);
152
153 new->thread_keyring = keyring;
154 return 0;
155 }
156
157 /*
158 * Install a thread keyring to the current task if it didn't have one already.
159 *
160 * Return: 0 if a thread keyring is now present; -errno on failure.
161 */
install_thread_keyring(void)162 static int install_thread_keyring(void)
163 {
164 struct cred *new;
165 int ret;
166
167 new = prepare_creds();
168 if (!new)
169 return -ENOMEM;
170
171 ret = install_thread_keyring_to_cred(new);
172 if (ret < 0) {
173 abort_creds(new);
174 return ret;
175 }
176
177 return commit_creds(new);
178 }
179
180 /*
181 * Install a process keyring to the given credentials struct if it didn't have
182 * one already. This is allowed to overrun the quota.
183 *
184 * Return: 0 if a process keyring is now present; -errno on failure.
185 */
install_process_keyring_to_cred(struct cred * new)186 int install_process_keyring_to_cred(struct cred *new)
187 {
188 struct key *keyring;
189
190 if (new->process_keyring)
191 return 0;
192
193 keyring = keyring_alloc("_pid", new->uid, new->gid, new,
194 KEY_POS_ALL | KEY_USR_VIEW,
195 KEY_ALLOC_QUOTA_OVERRUN,
196 NULL, NULL);
197 if (IS_ERR(keyring))
198 return PTR_ERR(keyring);
199
200 new->process_keyring = keyring;
201 return 0;
202 }
203
204 /*
205 * Install a process keyring to the current task if it didn't have one already.
206 *
207 * Return: 0 if a process keyring is now present; -errno on failure.
208 */
install_process_keyring(void)209 static int install_process_keyring(void)
210 {
211 struct cred *new;
212 int ret;
213
214 new = prepare_creds();
215 if (!new)
216 return -ENOMEM;
217
218 ret = install_process_keyring_to_cred(new);
219 if (ret < 0) {
220 abort_creds(new);
221 return ret;
222 }
223
224 return commit_creds(new);
225 }
226
227 /*
228 * Install the given keyring as the session keyring of the given credentials
229 * struct, replacing the existing one if any. If the given keyring is NULL,
230 * then install a new anonymous session keyring.
231 *
232 * Return: 0 on success; -errno on failure.
233 */
install_session_keyring_to_cred(struct cred * cred,struct key * keyring)234 int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
235 {
236 unsigned long flags;
237 struct key *old;
238
239 might_sleep();
240
241 /* create an empty session keyring */
242 if (!keyring) {
243 flags = KEY_ALLOC_QUOTA_OVERRUN;
244 if (cred->session_keyring)
245 flags = KEY_ALLOC_IN_QUOTA;
246
247 keyring = keyring_alloc("_ses", cred->uid, cred->gid, cred,
248 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
249 flags, NULL, NULL);
250 if (IS_ERR(keyring))
251 return PTR_ERR(keyring);
252 } else {
253 __key_get(keyring);
254 }
255
256 /* install the keyring */
257 old = cred->session_keyring;
258 rcu_assign_pointer(cred->session_keyring, keyring);
259
260 if (old)
261 key_put(old);
262
263 return 0;
264 }
265
266 /*
267 * Install the given keyring as the session keyring of the current task,
268 * replacing the existing one if any. If the given keyring is NULL, then
269 * install a new anonymous session keyring.
270 *
271 * Return: 0 on success; -errno on failure.
272 */
install_session_keyring(struct key * keyring)273 static int install_session_keyring(struct key *keyring)
274 {
275 struct cred *new;
276 int ret;
277
278 new = prepare_creds();
279 if (!new)
280 return -ENOMEM;
281
282 ret = install_session_keyring_to_cred(new, keyring);
283 if (ret < 0) {
284 abort_creds(new);
285 return ret;
286 }
287
288 return commit_creds(new);
289 }
290
291 /*
292 * Handle the fsuid changing.
293 */
key_fsuid_changed(struct task_struct * tsk)294 void key_fsuid_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->uid = tsk->cred->fsuid;
301 up_write(&tsk->cred->thread_keyring->sem);
302 }
303 }
304
305 /*
306 * Handle the fsgid changing.
307 */
key_fsgid_changed(struct task_struct * tsk)308 void key_fsgid_changed(struct task_struct *tsk)
309 {
310 /* update the ownership of the thread keyring */
311 BUG_ON(!tsk->cred);
312 if (tsk->cred->thread_keyring) {
313 down_write(&tsk->cred->thread_keyring->sem);
314 tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
315 up_write(&tsk->cred->thread_keyring->sem);
316 }
317 }
318
319 /*
320 * Search the process keyrings attached to the supplied cred for the first
321 * matching key.
322 *
323 * The search criteria are the type and the match function. The description is
324 * given to the match function as a parameter, but doesn't otherwise influence
325 * the search. Typically the match function will compare the description
326 * parameter to the key's description.
327 *
328 * This can only search keyrings that grant Search permission to the supplied
329 * credentials. Keyrings linked to searched keyrings will also be searched if
330 * they grant Search permission too. Keys can only be found if they grant
331 * Search permission to the credentials.
332 *
333 * Returns a pointer to the key with the key usage count incremented if
334 * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
335 * matched negative keys.
336 *
337 * In the case of a successful return, the possession attribute is set on the
338 * returned key reference.
339 */
search_my_process_keyrings(struct keyring_search_context * ctx)340 key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx)
341 {
342 key_ref_t key_ref, ret, err;
343
344 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
345 * searchable, but we failed to find a key or we found a negative key;
346 * otherwise we want to return a sample error (probably -EACCES) if
347 * none of the keyrings were searchable
348 *
349 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
350 */
351 key_ref = NULL;
352 ret = NULL;
353 err = ERR_PTR(-EAGAIN);
354
355 /* search the thread keyring first */
356 if (ctx->cred->thread_keyring) {
357 key_ref = keyring_search_aux(
358 make_key_ref(ctx->cred->thread_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 case -ENOKEY: /* negative key */
365 ret = key_ref;
366 break;
367 default:
368 err = key_ref;
369 break;
370 }
371 }
372
373 /* search the process keyring second */
374 if (ctx->cred->process_keyring) {
375 key_ref = keyring_search_aux(
376 make_key_ref(ctx->cred->process_keyring, 1), ctx);
377 if (!IS_ERR(key_ref))
378 goto found;
379
380 switch (PTR_ERR(key_ref)) {
381 case -EAGAIN: /* no key */
382 if (ret)
383 break;
384 case -ENOKEY: /* negative key */
385 ret = key_ref;
386 break;
387 default:
388 err = key_ref;
389 break;
390 }
391 }
392
393 /* search the session keyring */
394 if (ctx->cred->session_keyring) {
395 rcu_read_lock();
396 key_ref = keyring_search_aux(
397 make_key_ref(rcu_dereference(ctx->cred->session_keyring), 1),
398 ctx);
399 rcu_read_unlock();
400
401 if (!IS_ERR(key_ref))
402 goto found;
403
404 switch (PTR_ERR(key_ref)) {
405 case -EAGAIN: /* no key */
406 if (ret)
407 break;
408 case -ENOKEY: /* negative key */
409 ret = key_ref;
410 break;
411 default:
412 err = key_ref;
413 break;
414 }
415 }
416 /* or search the user-session keyring */
417 else if (ctx->cred->user->session_keyring) {
418 key_ref = keyring_search_aux(
419 make_key_ref(ctx->cred->user->session_keyring, 1),
420 ctx);
421 if (!IS_ERR(key_ref))
422 goto found;
423
424 switch (PTR_ERR(key_ref)) {
425 case -EAGAIN: /* no key */
426 if (ret)
427 break;
428 case -ENOKEY: /* negative key */
429 ret = key_ref;
430 break;
431 default:
432 err = key_ref;
433 break;
434 }
435 }
436
437 /* no key - decide on the error we're going to go for */
438 key_ref = ret ? ret : err;
439
440 found:
441 return key_ref;
442 }
443
444 /*
445 * Search the process keyrings attached to the supplied cred for the first
446 * matching key in the manner of search_my_process_keyrings(), but also search
447 * the keys attached to the assumed authorisation key using its credentials if
448 * one is available.
449 *
450 * Return same as search_my_process_keyrings().
451 */
search_process_keyrings(struct keyring_search_context * ctx)452 key_ref_t search_process_keyrings(struct keyring_search_context *ctx)
453 {
454 struct request_key_auth *rka;
455 key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
456
457 might_sleep();
458
459 key_ref = search_my_process_keyrings(ctx);
460 if (!IS_ERR(key_ref))
461 goto found;
462 err = key_ref;
463
464 /* if this process has an instantiation authorisation key, then we also
465 * search the keyrings of the process mentioned there
466 * - we don't permit access to request_key auth keys via this method
467 */
468 if (ctx->cred->request_key_auth &&
469 ctx->cred == current_cred() &&
470 ctx->index_key.type != &key_type_request_key_auth
471 ) {
472 const struct cred *cred = ctx->cred;
473
474 /* defend against the auth key being revoked */
475 down_read(&cred->request_key_auth->sem);
476
477 if (key_validate(ctx->cred->request_key_auth) == 0) {
478 rka = ctx->cred->request_key_auth->payload.data[0];
479
480 ctx->cred = rka->cred;
481 key_ref = search_process_keyrings(ctx);
482 ctx->cred = cred;
483
484 up_read(&cred->request_key_auth->sem);
485
486 if (!IS_ERR(key_ref))
487 goto found;
488
489 ret = key_ref;
490 } else {
491 up_read(&cred->request_key_auth->sem);
492 }
493 }
494
495 /* no key - decide on the error we're going to go for */
496 if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
497 key_ref = ERR_PTR(-ENOKEY);
498 else if (err == ERR_PTR(-EACCES))
499 key_ref = ret;
500 else
501 key_ref = err;
502
503 found:
504 return key_ref;
505 }
506
507 /*
508 * See if the key we're looking at is the target key.
509 */
lookup_user_key_possessed(const struct key * key,const struct key_match_data * match_data)510 bool lookup_user_key_possessed(const struct key *key,
511 const struct key_match_data *match_data)
512 {
513 return key == match_data->raw_data;
514 }
515
516 /*
517 * Look up a key ID given us by userspace with a given permissions mask to get
518 * the key it refers to.
519 *
520 * Flags can be passed to request that special keyrings be created if referred
521 * to directly, to permit partially constructed keys to be found and to skip
522 * validity and permission checks on the found key.
523 *
524 * Returns a pointer to the key with an incremented usage count if successful;
525 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
526 * to a key or the best found key was a negative key; -EKEYREVOKED or
527 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
528 * found key doesn't grant the requested permit or the LSM denied access to it;
529 * or -ENOMEM if a special keyring couldn't be created.
530 *
531 * In the case of a successful return, the possession attribute is set on the
532 * returned key reference.
533 */
lookup_user_key(key_serial_t id,unsigned long lflags,key_perm_t perm)534 key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
535 key_perm_t perm)
536 {
537 struct keyring_search_context ctx = {
538 .match_data.cmp = lookup_user_key_possessed,
539 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
540 .flags = KEYRING_SEARCH_NO_STATE_CHECK,
541 };
542 struct request_key_auth *rka;
543 struct key *key;
544 key_ref_t key_ref, skey_ref;
545 int ret;
546
547 try_again:
548 ctx.cred = get_current_cred();
549 key_ref = ERR_PTR(-ENOKEY);
550
551 switch (id) {
552 case KEY_SPEC_THREAD_KEYRING:
553 if (!ctx.cred->thread_keyring) {
554 if (!(lflags & KEY_LOOKUP_CREATE))
555 goto error;
556
557 ret = install_thread_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->thread_keyring;
566 __key_get(key);
567 key_ref = make_key_ref(key, 1);
568 break;
569
570 case KEY_SPEC_PROCESS_KEYRING:
571 if (!ctx.cred->process_keyring) {
572 if (!(lflags & KEY_LOOKUP_CREATE))
573 goto error;
574
575 ret = install_process_keyring();
576 if (ret < 0) {
577 key_ref = ERR_PTR(ret);
578 goto error;
579 }
580 goto reget_creds;
581 }
582
583 key = ctx.cred->process_keyring;
584 __key_get(key);
585 key_ref = make_key_ref(key, 1);
586 break;
587
588 case KEY_SPEC_SESSION_KEYRING:
589 if (!ctx.cred->session_keyring) {
590 /* always install a session keyring upon access if one
591 * doesn't exist yet */
592 ret = install_user_keyrings();
593 if (ret < 0)
594 goto error;
595 if (lflags & KEY_LOOKUP_CREATE)
596 ret = join_session_keyring(NULL);
597 else
598 ret = install_session_keyring(
599 ctx.cred->user->session_keyring);
600
601 if (ret < 0)
602 goto error;
603 goto reget_creds;
604 } else if (ctx.cred->session_keyring ==
605 ctx.cred->user->session_keyring &&
606 lflags & KEY_LOOKUP_CREATE) {
607 ret = join_session_keyring(NULL);
608 if (ret < 0)
609 goto error;
610 goto reget_creds;
611 }
612
613 rcu_read_lock();
614 key = rcu_dereference(ctx.cred->session_keyring);
615 __key_get(key);
616 rcu_read_unlock();
617 key_ref = make_key_ref(key, 1);
618 break;
619
620 case KEY_SPEC_USER_KEYRING:
621 if (!ctx.cred->user->uid_keyring) {
622 ret = install_user_keyrings();
623 if (ret < 0)
624 goto error;
625 }
626
627 key = ctx.cred->user->uid_keyring;
628 __key_get(key);
629 key_ref = make_key_ref(key, 1);
630 break;
631
632 case KEY_SPEC_USER_SESSION_KEYRING:
633 if (!ctx.cred->user->session_keyring) {
634 ret = install_user_keyrings();
635 if (ret < 0)
636 goto error;
637 }
638
639 key = ctx.cred->user->session_keyring;
640 __key_get(key);
641 key_ref = make_key_ref(key, 1);
642 break;
643
644 case KEY_SPEC_GROUP_KEYRING:
645 /* group keyrings are not yet supported */
646 key_ref = ERR_PTR(-EINVAL);
647 goto error;
648
649 case KEY_SPEC_REQKEY_AUTH_KEY:
650 key = ctx.cred->request_key_auth;
651 if (!key)
652 goto error;
653
654 __key_get(key);
655 key_ref = make_key_ref(key, 1);
656 break;
657
658 case KEY_SPEC_REQUESTOR_KEYRING:
659 if (!ctx.cred->request_key_auth)
660 goto error;
661
662 down_read(&ctx.cred->request_key_auth->sem);
663 if (test_bit(KEY_FLAG_REVOKED,
664 &ctx.cred->request_key_auth->flags)) {
665 key_ref = ERR_PTR(-EKEYREVOKED);
666 key = NULL;
667 } else {
668 rka = ctx.cred->request_key_auth->payload.data[0];
669 key = rka->dest_keyring;
670 __key_get(key);
671 }
672 up_read(&ctx.cred->request_key_auth->sem);
673 if (!key)
674 goto error;
675 key_ref = make_key_ref(key, 1);
676 break;
677
678 default:
679 key_ref = ERR_PTR(-EINVAL);
680 if (id < 1)
681 goto error;
682
683 key = key_lookup(id);
684 if (IS_ERR(key)) {
685 key_ref = ERR_CAST(key);
686 goto error;
687 }
688
689 key_ref = make_key_ref(key, 0);
690
691 /* check to see if we possess the key */
692 ctx.index_key.type = key->type;
693 ctx.index_key.description = key->description;
694 ctx.index_key.desc_len = strlen(key->description);
695 ctx.match_data.raw_data = key;
696 kdebug("check possessed");
697 skey_ref = search_process_keyrings(&ctx);
698 kdebug("possessed=%p", skey_ref);
699
700 if (!IS_ERR(skey_ref)) {
701 key_put(key);
702 key_ref = skey_ref;
703 }
704
705 break;
706 }
707
708 /* unlink does not use the nominated key in any way, so can skip all
709 * the permission checks as it is only concerned with the keyring */
710 if (lflags & KEY_LOOKUP_FOR_UNLINK) {
711 ret = 0;
712 goto error;
713 }
714
715 if (!(lflags & KEY_LOOKUP_PARTIAL)) {
716 ret = wait_for_key_construction(key, true);
717 switch (ret) {
718 case -ERESTARTSYS:
719 goto invalid_key;
720 default:
721 if (perm)
722 goto invalid_key;
723 case 0:
724 break;
725 }
726 } else if (perm) {
727 ret = key_validate(key);
728 if (ret < 0)
729 goto invalid_key;
730 }
731
732 ret = -EIO;
733 if (!(lflags & KEY_LOOKUP_PARTIAL) &&
734 key_read_state(key) == KEY_IS_UNINSTANTIATED)
735 goto invalid_key;
736
737 /* check the permissions */
738 ret = key_task_permission(key_ref, ctx.cred, perm);
739 if (ret < 0)
740 goto invalid_key;
741
742 key->last_used_at = current_kernel_time().tv_sec;
743
744 error:
745 put_cred(ctx.cred);
746 return key_ref;
747
748 invalid_key:
749 key_ref_put(key_ref);
750 key_ref = ERR_PTR(ret);
751 goto error;
752
753 /* if we attempted to install a keyring, then it may have caused new
754 * creds to be installed */
755 reget_creds:
756 put_cred(ctx.cred);
757 goto try_again;
758 }
759
760 /*
761 * Join the named keyring as the session keyring if possible else attempt to
762 * create a new one of that name and join that.
763 *
764 * If the name is NULL, an empty anonymous keyring will be installed as the
765 * session keyring.
766 *
767 * Named session keyrings are joined with a semaphore held to prevent the
768 * keyrings from going away whilst the attempt is made to going them and also
769 * to prevent a race in creating compatible session keyrings.
770 */
join_session_keyring(const char * name)771 long join_session_keyring(const char *name)
772 {
773 const struct cred *old;
774 struct cred *new;
775 struct key *keyring;
776 long ret, serial;
777
778 new = prepare_creds();
779 if (!new)
780 return -ENOMEM;
781 old = current_cred();
782
783 /* if no name is provided, install an anonymous keyring */
784 if (!name) {
785 ret = install_session_keyring_to_cred(new, NULL);
786 if (ret < 0)
787 goto error;
788
789 serial = new->session_keyring->serial;
790 ret = commit_creds(new);
791 if (ret == 0)
792 ret = serial;
793 goto okay;
794 }
795
796 /* allow the user to join or create a named keyring */
797 mutex_lock(&key_session_mutex);
798
799 /* look for an existing keyring of this name */
800 keyring = find_keyring_by_name(name, false);
801 if (PTR_ERR(keyring) == -ENOKEY) {
802 /* not found - try and create a new one */
803 keyring = keyring_alloc(
804 name, old->uid, old->gid, old,
805 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_LINK,
806 KEY_ALLOC_IN_QUOTA, NULL, NULL);
807 if (IS_ERR(keyring)) {
808 ret = PTR_ERR(keyring);
809 goto error2;
810 }
811 } else if (IS_ERR(keyring)) {
812 ret = PTR_ERR(keyring);
813 goto error2;
814 } else if (keyring == new->session_keyring) {
815 ret = 0;
816 goto error3;
817 }
818
819 /* we've got a keyring - now to install it */
820 ret = install_session_keyring_to_cred(new, keyring);
821 if (ret < 0)
822 goto error3;
823
824 commit_creds(new);
825 mutex_unlock(&key_session_mutex);
826
827 ret = keyring->serial;
828 key_put(keyring);
829 okay:
830 return ret;
831
832 error3:
833 key_put(keyring);
834 error2:
835 mutex_unlock(&key_session_mutex);
836 error:
837 abort_creds(new);
838 return ret;
839 }
840
841 /*
842 * Replace a process's session keyring on behalf of one of its children when
843 * the target process is about to resume userspace execution.
844 */
key_change_session_keyring(struct callback_head * twork)845 void key_change_session_keyring(struct callback_head *twork)
846 {
847 const struct cred *old = current_cred();
848 struct cred *new = container_of(twork, struct cred, rcu);
849
850 if (unlikely(current->flags & PF_EXITING)) {
851 put_cred(new);
852 return;
853 }
854
855 new-> uid = old-> uid;
856 new-> euid = old-> euid;
857 new-> suid = old-> suid;
858 new->fsuid = old->fsuid;
859 new-> gid = old-> gid;
860 new-> egid = old-> egid;
861 new-> sgid = old-> sgid;
862 new->fsgid = old->fsgid;
863 new->user = get_uid(old->user);
864 new->user_ns = get_user_ns(old->user_ns);
865 new->group_info = get_group_info(old->group_info);
866
867 new->securebits = old->securebits;
868 new->cap_inheritable = old->cap_inheritable;
869 new->cap_permitted = old->cap_permitted;
870 new->cap_effective = old->cap_effective;
871 new->cap_ambient = old->cap_ambient;
872 new->cap_bset = old->cap_bset;
873
874 new->jit_keyring = old->jit_keyring;
875 new->thread_keyring = key_get(old->thread_keyring);
876 new->process_keyring = key_get(old->process_keyring);
877
878 security_transfer_creds(new, old);
879
880 commit_creds(new);
881 }
882
883 /*
884 * Make sure that root's user and user-session keyrings exist.
885 */
init_root_keyring(void)886 static int __init init_root_keyring(void)
887 {
888 return install_user_keyrings();
889 }
890
891 late_initcall(init_root_keyring);
892