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		= 0,
 38	.user_ns	= &init_user_ns,
 39};
 40
 41/*
 42 * Install the user and user session keyrings for the current process's UID.
 43 */
 44int install_user_keyrings(void)
 45{
 46	struct user_struct *user;
 47	const struct cred *cred;
 48	struct key *uid_keyring, *session_keyring;
 
 49	char buf[20];
 50	int ret;
 
 51
 
 52	cred = current_cred();
 53	user = cred->user;
 
 54
 55	kenter("%p{%u}", user, user->uid);
 56
 57	if (user->uid_keyring) {
 58		kleave(" = 0 [exist]");
 59		return 0;
 60	}
 61
 62	mutex_lock(&key_user_keyring_mutex);
 63	ret = 0;
 64
 65	if (!user->uid_keyring) {
 66		/* get the UID-specific keyring
 67		 * - there may be one in existence already as it may have been
 68		 *   pinned by a session, but the user_struct pointing to it
 69		 *   may have been destroyed by setuid */
 70		sprintf(buf, "_uid.%u", user->uid);
 71
 72		uid_keyring = find_keyring_by_name(buf, true);
 73		if (IS_ERR(uid_keyring)) {
 74			uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1,
 75						    cred, KEY_ALLOC_IN_QUOTA,
 76						    NULL);
 
 77			if (IS_ERR(uid_keyring)) {
 78				ret = PTR_ERR(uid_keyring);
 79				goto error;
 80			}
 81		}
 82
 83		/* get a default session keyring (which might also exist
 84		 * already) */
 85		sprintf(buf, "_uid_ses.%u", user->uid);
 86
 87		session_keyring = find_keyring_by_name(buf, true);
 88		if (IS_ERR(session_keyring)) {
 89			session_keyring =
 90				keyring_alloc(buf, user->uid, (gid_t) -1,
 91					      cred, KEY_ALLOC_IN_QUOTA, NULL);
 
 
 92			if (IS_ERR(session_keyring)) {
 93				ret = PTR_ERR(session_keyring);
 94				goto error_release;
 95			}
 96
 97			/* we install a link from the user session keyring to
 98			 * the user keyring */
 99			ret = key_link(session_keyring, uid_keyring);
100			if (ret < 0)
101				goto error_release_both;
102		}
103
104		/* install the keyrings */
105		user->uid_keyring = uid_keyring;
106		user->session_keyring = session_keyring;
107	}
108
109	mutex_unlock(&key_user_keyring_mutex);
110	kleave(" = 0");
111	return 0;
112
113error_release_both:
114	key_put(session_keyring);
115error_release:
116	key_put(uid_keyring);
117error:
118	mutex_unlock(&key_user_keyring_mutex);
119	kleave(" = %d", ret);
120	return ret;
121}
122
123/*
124 * Install a fresh thread keyring directly to new credentials.  This keyring is
125 * allowed to overrun the quota.
126 */
127int install_thread_keyring_to_cred(struct cred *new)
128{
129	struct key *keyring;
130
131	keyring = keyring_alloc("_tid", new->uid, new->gid, new,
132				KEY_ALLOC_QUOTA_OVERRUN, NULL);
 
 
133	if (IS_ERR(keyring))
134		return PTR_ERR(keyring);
135
136	new->thread_keyring = keyring;
137	return 0;
138}
139
140/*
141 * Install a fresh thread keyring, discarding the old one.
142 */
143static int install_thread_keyring(void)
144{
145	struct cred *new;
146	int ret;
147
148	new = prepare_creds();
149	if (!new)
150		return -ENOMEM;
151
152	BUG_ON(new->thread_keyring);
153
154	ret = install_thread_keyring_to_cred(new);
155	if (ret < 0) {
156		abort_creds(new);
157		return ret;
158	}
159
160	return commit_creds(new);
161}
162
163/*
164 * Install a process keyring directly to a credentials struct.
165 *
166 * Returns -EEXIST if there was already a process keyring, 0 if one installed,
167 * and other value on any other error
168 */
169int install_process_keyring_to_cred(struct cred *new)
170{
171	struct key *keyring;
172	int ret;
173
174	if (new->tgcred->process_keyring)
175		return -EEXIST;
176
177	keyring = keyring_alloc("_pid", new->uid, new->gid,
178				new, KEY_ALLOC_QUOTA_OVERRUN, NULL);
 
 
179	if (IS_ERR(keyring))
180		return PTR_ERR(keyring);
181
182	spin_lock_irq(&new->tgcred->lock);
183	if (!new->tgcred->process_keyring) {
184		new->tgcred->process_keyring = keyring;
185		keyring = NULL;
186		ret = 0;
187	} else {
188		ret = -EEXIST;
189	}
190	spin_unlock_irq(&new->tgcred->lock);
191	key_put(keyring);
192	return ret;
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->tgcred->session_keyring)
234			flags = KEY_ALLOC_IN_QUOTA;
235
236		keyring = keyring_alloc("_ses", cred->uid, cred->gid,
237					cred, flags, NULL);
 
238		if (IS_ERR(keyring))
239			return PTR_ERR(keyring);
240	} else {
241		atomic_inc(&keyring->usage);
242	}
243
244	/* install the keyring */
245	spin_lock_irq(&cred->tgcred->lock);
246	old = cred->tgcred->session_keyring;
247	rcu_assign_pointer(cred->tgcred->session_keyring, keyring);
248	spin_unlock_irq(&cred->tgcred->lock);
249
250	/* we're using RCU on the pointer, but there's no point synchronising
251	 * on it if it didn't previously point to anything */
252	if (old) {
253		synchronize_rcu();
254		key_put(old);
255	}
256
257	return 0;
258}
259
260/*
261 * Install a session keyring, discarding the old one.  If a keyring is not
262 * supplied, an empty one is invented.
263 */
264static int install_session_keyring(struct key *keyring)
265{
266	struct cred *new;
267	int ret;
268
269	new = prepare_creds();
270	if (!new)
271		return -ENOMEM;
272
273	ret = install_session_keyring_to_cred(new, NULL);
274	if (ret < 0) {
275		abort_creds(new);
276		return ret;
277	}
278
279	return commit_creds(new);
280}
281
282/*
283 * Handle the fsuid changing.
284 */
285void key_fsuid_changed(struct task_struct *tsk)
286{
287	/* update the ownership of the thread keyring */
288	BUG_ON(!tsk->cred);
289	if (tsk->cred->thread_keyring) {
290		down_write(&tsk->cred->thread_keyring->sem);
291		tsk->cred->thread_keyring->uid = tsk->cred->fsuid;
292		up_write(&tsk->cred->thread_keyring->sem);
293	}
294}
295
296/*
297 * Handle the fsgid changing.
298 */
299void key_fsgid_changed(struct task_struct *tsk)
300{
301	/* update the ownership of the thread keyring */
302	BUG_ON(!tsk->cred);
303	if (tsk->cred->thread_keyring) {
304		down_write(&tsk->cred->thread_keyring->sem);
305		tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
306		up_write(&tsk->cred->thread_keyring->sem);
307	}
308}
309
310/*
311 * Search the process keyrings attached to the supplied cred for the first
312 * matching key.
313 *
314 * The search criteria are the type and the match function.  The description is
315 * given to the match function as a parameter, but doesn't otherwise influence
316 * the search.  Typically the match function will compare the description
317 * parameter to the key's description.
318 *
319 * This can only search keyrings that grant Search permission to the supplied
320 * credentials.  Keyrings linked to searched keyrings will also be searched if
321 * they grant Search permission too.  Keys can only be found if they grant
322 * Search permission to the credentials.
323 *
324 * Returns a pointer to the key with the key usage count incremented if
325 * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
326 * matched negative keys.
327 *
328 * In the case of a successful return, the possession attribute is set on the
329 * returned key reference.
330 */
331key_ref_t search_my_process_keyrings(struct key_type *type,
332				     const void *description,
333				     key_match_func_t match,
334				     bool no_state_check,
335				     const struct cred *cred)
336{
337	key_ref_t key_ref, ret, err;
338
339	/* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
340	 * searchable, but we failed to find a key or we found a negative key;
341	 * otherwise we want to return a sample error (probably -EACCES) if
342	 * none of the keyrings were searchable
343	 *
344	 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
345	 */
346	key_ref = NULL;
347	ret = NULL;
348	err = ERR_PTR(-EAGAIN);
349
350	/* search the thread keyring first */
351	if (cred->thread_keyring) {
352		key_ref = keyring_search_aux(
353			make_key_ref(cred->thread_keyring, 1),
354			cred, type, description, match, no_state_check);
355		if (!IS_ERR(key_ref))
356			goto found;
357
358		switch (PTR_ERR(key_ref)) {
359		case -EAGAIN: /* no key */
360			if (ret)
361				break;
362		case -ENOKEY: /* negative key */
363			ret = key_ref;
364			break;
365		default:
366			err = key_ref;
367			break;
368		}
369	}
370
371	/* search the process keyring second */
372	if (cred->tgcred->process_keyring) {
373		key_ref = keyring_search_aux(
374			make_key_ref(cred->tgcred->process_keyring, 1),
375			cred, type, description, match, no_state_check);
376		if (!IS_ERR(key_ref))
377			goto found;
378
379		switch (PTR_ERR(key_ref)) {
380		case -EAGAIN: /* no key */
381			if (ret)
382				break;
383		case -ENOKEY: /* negative key */
384			ret = key_ref;
385			break;
386		default:
387			err = key_ref;
388			break;
389		}
390	}
391
392	/* search the session keyring */
393	if (cred->tgcred->session_keyring) {
394		rcu_read_lock();
395		key_ref = keyring_search_aux(
396			make_key_ref(rcu_dereference(
397					     cred->tgcred->session_keyring),
398				     1),
399			cred, type, description, match, no_state_check);
400		rcu_read_unlock();
401
402		if (!IS_ERR(key_ref))
403			goto found;
404
405		switch (PTR_ERR(key_ref)) {
406		case -EAGAIN: /* no key */
407			if (ret)
408				break;
409		case -ENOKEY: /* negative key */
410			ret = key_ref;
411			break;
412		default:
413			err = key_ref;
414			break;
415		}
416	}
417	/* or search the user-session keyring */
418	else if (cred->user->session_keyring) {
419		key_ref = keyring_search_aux(
420			make_key_ref(cred->user->session_keyring, 1),
421			cred, type, description, match, no_state_check);
422		if (!IS_ERR(key_ref))
423			goto found;
424
425		switch (PTR_ERR(key_ref)) {
426		case -EAGAIN: /* no key */
427			if (ret)
428				break;
429		case -ENOKEY: /* negative key */
430			ret = key_ref;
431			break;
432		default:
433			err = key_ref;
434			break;
435		}
436	}
437
438	/* no key - decide on the error we're going to go for */
439	key_ref = ret ? ret : err;
440
441found:
442	return key_ref;
443}
444
445/*
446 * Search the process keyrings attached to the supplied cred for the first
447 * matching key in the manner of search_my_process_keyrings(), but also search
448 * the keys attached to the assumed authorisation key using its credentials if
449 * one is available.
450 *
451 * Return same as search_my_process_keyrings().
452 */
453key_ref_t search_process_keyrings(struct key_type *type,
454				  const void *description,
455				  key_match_func_t match,
456				  const struct cred *cred)
457{
458	struct request_key_auth *rka;
459	key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
460
461	might_sleep();
462
463	key_ref = search_my_process_keyrings(type, description, match,
464					     false, cred);
465	if (!IS_ERR(key_ref))
466		goto found;
467	err = key_ref;
468
469	/* if this process has an instantiation authorisation key, then we also
470	 * search the keyrings of the process mentioned there
471	 * - we don't permit access to request_key auth keys via this method
472	 */
473	if (cred->request_key_auth &&
474	    cred == current_cred() &&
475	    type != &key_type_request_key_auth
476	    ) {
 
 
477		/* defend against the auth key being revoked */
478		down_read(&cred->request_key_auth->sem);
479
480		if (key_validate(cred->request_key_auth) == 0) {
481			rka = cred->request_key_auth->payload.data;
482
483			key_ref = search_process_keyrings(type, description,
484							  match, rka->cred);
 
485
486			up_read(&cred->request_key_auth->sem);
487
488			if (!IS_ERR(key_ref))
489				goto found;
490
491			ret = key_ref;
492		} else {
493			up_read(&cred->request_key_auth->sem);
494		}
495	}
496
497	/* no key - decide on the error we're going to go for */
498	if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
499		key_ref = ERR_PTR(-ENOKEY);
500	else if (err == ERR_PTR(-EACCES))
501		key_ref = ret;
502	else
503		key_ref = err;
504
505found:
506	return key_ref;
507}
508
509/*
510 * See if the key we're looking at is the target key.
511 */
512int lookup_user_key_possessed(const struct key *key, const void *target)
 
513{
514	return key == target;
515}
516
517/*
518 * Look up a key ID given us by userspace with a given permissions mask to get
519 * the key it refers to.
520 *
521 * Flags can be passed to request that special keyrings be created if referred
522 * to directly, to permit partially constructed keys to be found and to skip
523 * validity and permission checks on the found key.
524 *
525 * Returns a pointer to the key with an incremented usage count if successful;
526 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
527 * to a key or the best found key was a negative key; -EKEYREVOKED or
528 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
529 * found key doesn't grant the requested permit or the LSM denied access to it;
530 * or -ENOMEM if a special keyring couldn't be created.
531 *
532 * In the case of a successful return, the possession attribute is set on the
533 * returned key reference.
534 */
535key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
536			  key_perm_t perm)
537{
 
 
 
 
 
538	struct request_key_auth *rka;
539	const struct cred *cred;
540	struct key *key;
541	key_ref_t key_ref, skey_ref;
542	int ret;
543
544try_again:
545	cred = get_current_cred();
546	key_ref = ERR_PTR(-ENOKEY);
547
548	switch (id) {
549	case KEY_SPEC_THREAD_KEYRING:
550		if (!cred->thread_keyring) {
551			if (!(lflags & KEY_LOOKUP_CREATE))
552				goto error;
553
554			ret = install_thread_keyring();
555			if (ret < 0) {
556				key_ref = ERR_PTR(ret);
557				goto error;
558			}
559			goto reget_creds;
560		}
561
562		key = cred->thread_keyring;
563		atomic_inc(&key->usage);
564		key_ref = make_key_ref(key, 1);
565		break;
566
567	case KEY_SPEC_PROCESS_KEYRING:
568		if (!cred->tgcred->process_keyring) {
569			if (!(lflags & KEY_LOOKUP_CREATE))
570				goto error;
571
572			ret = install_process_keyring();
573			if (ret < 0) {
574				key_ref = ERR_PTR(ret);
575				goto error;
576			}
577			goto reget_creds;
578		}
579
580		key = cred->tgcred->process_keyring;
581		atomic_inc(&key->usage);
582		key_ref = make_key_ref(key, 1);
583		break;
584
585	case KEY_SPEC_SESSION_KEYRING:
586		if (!cred->tgcred->session_keyring) {
587			/* always install a session keyring upon access if one
588			 * doesn't exist yet */
589			ret = install_user_keyrings();
590			if (ret < 0)
591				goto error;
592			ret = install_session_keyring(
593				cred->user->session_keyring);
 
 
 
594
595			if (ret < 0)
596				goto error;
597			goto reget_creds;
 
 
 
 
 
 
 
598		}
599
600		rcu_read_lock();
601		key = rcu_dereference(cred->tgcred->session_keyring);
602		atomic_inc(&key->usage);
603		rcu_read_unlock();
604		key_ref = make_key_ref(key, 1);
605		break;
606
607	case KEY_SPEC_USER_KEYRING:
608		if (!cred->user->uid_keyring) {
609			ret = install_user_keyrings();
610			if (ret < 0)
611				goto error;
612		}
613
614		key = cred->user->uid_keyring;
615		atomic_inc(&key->usage);
616		key_ref = make_key_ref(key, 1);
617		break;
618
619	case KEY_SPEC_USER_SESSION_KEYRING:
620		if (!cred->user->session_keyring) {
621			ret = install_user_keyrings();
622			if (ret < 0)
623				goto error;
624		}
625
626		key = cred->user->session_keyring;
627		atomic_inc(&key->usage);
628		key_ref = make_key_ref(key, 1);
629		break;
630
631	case KEY_SPEC_GROUP_KEYRING:
632		/* group keyrings are not yet supported */
633		key_ref = ERR_PTR(-EINVAL);
634		goto error;
635
636	case KEY_SPEC_REQKEY_AUTH_KEY:
637		key = cred->request_key_auth;
638		if (!key)
639			goto error;
640
641		atomic_inc(&key->usage);
642		key_ref = make_key_ref(key, 1);
643		break;
644
645	case KEY_SPEC_REQUESTOR_KEYRING:
646		if (!cred->request_key_auth)
647			goto error;
648
649		down_read(&cred->request_key_auth->sem);
650		if (cred->request_key_auth->flags & KEY_FLAG_REVOKED) {
 
651			key_ref = ERR_PTR(-EKEYREVOKED);
652			key = NULL;
653		} else {
654			rka = cred->request_key_auth->payload.data;
655			key = rka->dest_keyring;
656			atomic_inc(&key->usage);
657		}
658		up_read(&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		skey_ref = search_process_keyrings(key->type, key,
679						   lookup_user_key_possessed,
680						   cred);
 
 
 
 
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, cred, perm);
721	if (ret < 0)
722		goto invalid_key;
723
 
 
724error:
725	put_cred(cred);
726	return key_ref;
727
728invalid_key:
729	key_ref_put(key_ref);
730	key_ref = ERR_PTR(ret);
731	goto error;
732
733	/* if we attempted to install a keyring, then it may have caused new
734	 * creds to be installed */
735reget_creds:
736	put_cred(cred);
737	goto try_again;
738}
739
740/*
741 * Join the named keyring as the session keyring if possible else attempt to
742 * create a new one of that name and join that.
743 *
744 * If the name is NULL, an empty anonymous keyring will be installed as the
745 * session keyring.
746 *
747 * Named session keyrings are joined with a semaphore held to prevent the
748 * keyrings from going away whilst the attempt is made to going them and also
749 * to prevent a race in creating compatible session keyrings.
750 */
751long join_session_keyring(const char *name)
752{
753	const struct cred *old;
754	struct cred *new;
755	struct key *keyring;
756	long ret, serial;
757
758	/* only permit this if there's a single thread in the thread group -
759	 * this avoids us having to adjust the creds on all threads and risking
760	 * ENOMEM */
761	if (!current_is_single_threaded())
762		return -EMLINK;
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->tgcred->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(name, old->uid, old->gid, old,
790					KEY_ALLOC_IN_QUOTA, NULL);
 
 
791		if (IS_ERR(keyring)) {
792			ret = PTR_ERR(keyring);
793			goto error2;
794		}
795	} else if (IS_ERR(keyring)) {
796		ret = PTR_ERR(keyring);
797		goto error2;
 
 
 
 
798	}
799
800	/* we've got a keyring - now to install it */
801	ret = install_session_keyring_to_cred(new, keyring);
802	if (ret < 0)
803		goto error2;
804
805	commit_creds(new);
806	mutex_unlock(&key_session_mutex);
807
808	ret = keyring->serial;
809	key_put(keyring);
810okay:
811	return ret;
812
813error2:
814	mutex_unlock(&key_session_mutex);
815error:
816	abort_creds(new);
817	return ret;
818}
819
820/*
821 * Replace a process's session keyring on behalf of one of its children when
822 * the target  process is about to resume userspace execution.
823 */
824void key_replace_session_keyring(void)
825{
826	const struct cred *old;
827	struct cred *new;
828
829	if (!current->replacement_session_keyring)
830		return;
831
832	write_lock_irq(&tasklist_lock);
833	new = current->replacement_session_keyring;
834	current->replacement_session_keyring = NULL;
835	write_unlock_irq(&tasklist_lock);
836
837	if (!new)
 
838		return;
 
839
840	old = current_cred();
841	new->  uid	= old->  uid;
842	new-> euid	= old-> euid;
843	new-> suid	= old-> suid;
844	new->fsuid	= old->fsuid;
845	new->  gid	= old->  gid;
846	new-> egid	= old-> egid;
847	new-> sgid	= old-> sgid;
848	new->fsgid	= old->fsgid;
849	new->user	= get_uid(old->user);
850	new->user_ns	= new->user->user_ns;
851	new->group_info	= get_group_info(old->group_info);
852
853	new->securebits	= old->securebits;
854	new->cap_inheritable	= old->cap_inheritable;
855	new->cap_permitted	= old->cap_permitted;
856	new->cap_effective	= old->cap_effective;
 
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->tgcred->tgid	= old->tgcred->tgid;
862	new->tgcred->process_keyring = key_get(old->tgcred->process_keyring);
863
864	security_transfer_creds(new, old);
865
866	commit_creds(new);
867}