1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* Request a key from userspace
  3 *
  4 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
  5 * Written by David Howells (dhowells@redhat.com)
  6 *
  7 * See Documentation/security/keys/request-key.rst
  8 */
  9
 10#include <linux/export.h>
 11#include <linux/sched.h>
 12#include <linux/kmod.h>
 13#include <linux/err.h>
 14#include <linux/keyctl.h>
 15#include <linux/slab.h>
 16#include <net/net_namespace.h>
 17#include "internal.h"
 18#include <keys/request_key_auth-type.h>
 19
 20#define key_negative_timeout	60	/* default timeout on a negative key's existence */
 21
 22static struct key *check_cached_key(struct keyring_search_context *ctx)
 23{
 24#ifdef CONFIG_KEYS_REQUEST_CACHE
 25	struct key *key = current->cached_requested_key;
 26
 27	if (key &&
 28	    ctx->match_data.cmp(key, &ctx->match_data) &&
 29	    !(key->flags & ((1 << KEY_FLAG_INVALIDATED) |
 30			    (1 << KEY_FLAG_REVOKED))))
 31		return key_get(key);
 32#endif
 33	return NULL;
 34}
 35
 36static void cache_requested_key(struct key *key)
 37{
 38#ifdef CONFIG_KEYS_REQUEST_CACHE
 39	struct task_struct *t = current;
 40
 41	key_put(t->cached_requested_key);
 42	t->cached_requested_key = key_get(key);
 43	set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
 44#endif
 45}
 46
 47/**
 48 * complete_request_key - Complete the construction of a key.
 49 * @authkey: The authorisation key.
 50 * @error: The success or failute of the construction.
 51 *
 52 * Complete the attempt to construct a key.  The key will be negated
 53 * if an error is indicated.  The authorisation key will be revoked
 54 * unconditionally.
 55 */
 56void complete_request_key(struct key *authkey, int error)
 57{
 58	struct request_key_auth *rka = get_request_key_auth(authkey);
 59	struct key *key = rka->target_key;
 60
 61	kenter("%d{%d},%d", authkey->serial, key->serial, error);
 62
 63	if (error < 0)
 64		key_negate_and_link(key, key_negative_timeout, NULL, authkey);
 65	else
 66		key_revoke(authkey);
 67}
 68EXPORT_SYMBOL(complete_request_key);
 69
 70/*
 71 * Initialise a usermode helper that is going to have a specific session
 72 * keyring.
 73 *
 74 * This is called in context of freshly forked kthread before kernel_execve(),
 75 * so we can simply install the desired session_keyring at this point.
 76 */
 77static int umh_keys_init(struct subprocess_info *info, struct cred *cred)
 78{
 79	struct key *keyring = info->data;
 80
 81	return install_session_keyring_to_cred(cred, keyring);
 82}
 83
 84/*
 85 * Clean up a usermode helper with session keyring.
 86 */
 87static void umh_keys_cleanup(struct subprocess_info *info)
 88{
 89	struct key *keyring = info->data;
 90	key_put(keyring);
 91}
 92
 93/*
 94 * Call a usermode helper with a specific session keyring.
 95 */
 96static int call_usermodehelper_keys(const char *path, char **argv, char **envp,
 97					struct key *session_keyring, int wait)
 98{
 99	struct subprocess_info *info;
100
101	info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL,
102					  umh_keys_init, umh_keys_cleanup,
103					  session_keyring);
104	if (!info)
105		return -ENOMEM;
106
107	key_get(session_keyring);
108	return call_usermodehelper_exec(info, wait);
109}
110
111/*
112 * Request userspace finish the construction of a key
113 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
114 */
115static int call_sbin_request_key(struct key *authkey, void *aux)
116{
117	static char const request_key[] = "/sbin/request-key";
118	struct request_key_auth *rka = get_request_key_auth(authkey);
119	const struct cred *cred = current_cred();
120	key_serial_t prkey, sskey;
121	struct key *key = rka->target_key, *keyring, *session, *user_session;
122	char *argv[9], *envp[3], uid_str[12], gid_str[12];
123	char key_str[12], keyring_str[3][12];
124	char desc[20];
125	int ret, i;
126
127	kenter("{%d},{%d},%s", key->serial, authkey->serial, rka->op);
128
129	ret = look_up_user_keyrings(NULL, &user_session);
130	if (ret < 0)
131		goto error_us;
132
133	/* allocate a new session keyring */
134	sprintf(desc, "_req.%u", key->serial);
135
136	cred = get_current_cred();
137	keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
138				KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
139				KEY_ALLOC_QUOTA_OVERRUN, NULL, NULL);
140	put_cred(cred);
141	if (IS_ERR(keyring)) {
142		ret = PTR_ERR(keyring);
143		goto error_alloc;
144	}
145
146	/* attach the auth key to the session keyring */
147	ret = key_link(keyring, authkey);
148	if (ret < 0)
149		goto error_link;
150
151	/* record the UID and GID */
152	sprintf(uid_str, "%d", from_kuid(&init_user_ns, cred->fsuid));
153	sprintf(gid_str, "%d", from_kgid(&init_user_ns, cred->fsgid));
154
155	/* we say which key is under construction */
156	sprintf(key_str, "%d", key->serial);
157
158	/* we specify the process's default keyrings */
159	sprintf(keyring_str[0], "%d",
160		cred->thread_keyring ? cred->thread_keyring->serial : 0);
161
162	prkey = 0;
163	if (cred->process_keyring)
164		prkey = cred->process_keyring->serial;
165	sprintf(keyring_str[1], "%d", prkey);
166
167	session = cred->session_keyring;
168	if (!session)
169		session = user_session;
170	sskey = session->serial;
171
172	sprintf(keyring_str[2], "%d", sskey);
173
174	/* set up a minimal environment */
175	i = 0;
176	envp[i++] = "HOME=/";
177	envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
178	envp[i] = NULL;
179
180	/* set up the argument list */
181	i = 0;
182	argv[i++] = (char *)request_key;
183	argv[i++] = (char *)rka->op;
184	argv[i++] = key_str;
185	argv[i++] = uid_str;
186	argv[i++] = gid_str;
187	argv[i++] = keyring_str[0];
188	argv[i++] = keyring_str[1];
189	argv[i++] = keyring_str[2];
190	argv[i] = NULL;
191
192	/* do it */
193	ret = call_usermodehelper_keys(request_key, argv, envp, keyring,
194				       UMH_WAIT_PROC);
195	kdebug("usermode -> 0x%x", ret);
196	if (ret >= 0) {
197		/* ret is the exit/wait code */
198		if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
199		    key_validate(key) < 0)
200			ret = -ENOKEY;
201		else
202			/* ignore any errors from userspace if the key was
203			 * instantiated */
204			ret = 0;
205	}
206
207error_link:
208	key_put(keyring);
209
210error_alloc:
211	key_put(user_session);
212error_us:
213	complete_request_key(authkey, ret);
214	kleave(" = %d", ret);
215	return ret;
216}
217
218/*
219 * Call out to userspace for key construction.
220 *
221 * Program failure is ignored in favour of key status.
222 */
223static int construct_key(struct key *key, const void *callout_info,
224			 size_t callout_len, void *aux,
225			 struct key *dest_keyring)
226{
227	request_key_actor_t actor;
228	struct key *authkey;
229	int ret;
230
231	kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
232
233	/* allocate an authorisation key */
234	authkey = request_key_auth_new(key, "create", callout_info, callout_len,
235				       dest_keyring);
236	if (IS_ERR(authkey))
237		return PTR_ERR(authkey);
238
239	/* Make the call */
240	actor = call_sbin_request_key;
241	if (key->type->request_key)
242		actor = key->type->request_key;
243
244	ret = actor(authkey, aux);
245
246	/* check that the actor called complete_request_key() prior to
247	 * returning an error */
248	WARN_ON(ret < 0 &&
249		!test_bit(KEY_FLAG_INVALIDATED, &authkey->flags));
250
251	key_put(authkey);
252	kleave(" = %d", ret);
253	return ret;
254}
255
256/*
257 * Get the appropriate destination keyring for the request.
258 *
259 * The keyring selected is returned with an extra reference upon it which the
260 * caller must release.
261 */
262static int construct_get_dest_keyring(struct key **_dest_keyring)
263{
264	struct request_key_auth *rka;
265	const struct cred *cred = current_cred();
266	struct key *dest_keyring = *_dest_keyring, *authkey;
267	int ret;
268
269	kenter("%p", dest_keyring);
270
271	/* find the appropriate keyring */
272	if (dest_keyring) {
273		/* the caller supplied one */
274		key_get(dest_keyring);
275	} else {
276		bool do_perm_check = true;
277
278		/* use a default keyring; falling through the cases until we
279		 * find one that we actually have */
280		switch (cred->jit_keyring) {
281		case KEY_REQKEY_DEFL_DEFAULT:
282		case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
283			if (cred->request_key_auth) {
284				authkey = cred->request_key_auth;
285				down_read(&authkey->sem);
286				rka = get_request_key_auth(authkey);
287				if (!test_bit(KEY_FLAG_REVOKED,
288					      &authkey->flags))
289					dest_keyring =
290						key_get(rka->dest_keyring);
291				up_read(&authkey->sem);
292				if (dest_keyring) {
293					do_perm_check = false;
294					break;
295				}
296			}
297
298			fallthrough;
299		case KEY_REQKEY_DEFL_THREAD_KEYRING:
300			dest_keyring = key_get(cred->thread_keyring);
301			if (dest_keyring)
302				break;
303
304			fallthrough;
305		case KEY_REQKEY_DEFL_PROCESS_KEYRING:
306			dest_keyring = key_get(cred->process_keyring);
307			if (dest_keyring)
308				break;
309
310			fallthrough;
311		case KEY_REQKEY_DEFL_SESSION_KEYRING:
312			dest_keyring = key_get(cred->session_keyring);
313
314			if (dest_keyring)
315				break;
316
317			fallthrough;
318		case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
319			ret = look_up_user_keyrings(NULL, &dest_keyring);
320			if (ret < 0)
321				return ret;
322			break;
323
324		case KEY_REQKEY_DEFL_USER_KEYRING:
325			ret = look_up_user_keyrings(&dest_keyring, NULL);
326			if (ret < 0)
327				return ret;
328			break;
329
330		case KEY_REQKEY_DEFL_GROUP_KEYRING:
331		default:
332			BUG();
333		}
334
335		/*
336		 * Require Write permission on the keyring.  This is essential
337		 * because the default keyring may be the session keyring, and
338		 * joining a keyring only requires Search permission.
339		 *
340		 * However, this check is skipped for the "requestor keyring" so
341		 * that /sbin/request-key can itself use request_key() to add
342		 * keys to the original requestor's destination keyring.
343		 */
344		if (dest_keyring && do_perm_check) {
345			ret = key_permission(make_key_ref(dest_keyring, 1),
346					     KEY_NEED_WRITE);
347			if (ret) {
348				key_put(dest_keyring);
349				return ret;
350			}
351		}
352	}
353
354	*_dest_keyring = dest_keyring;
355	kleave(" [dk %d]", key_serial(dest_keyring));
356	return 0;
357}
358
359/*
360 * Allocate a new key in under-construction state and attempt to link it in to
361 * the requested keyring.
362 *
363 * May return a key that's already under construction instead if there was a
364 * race between two thread calling request_key().
365 */
366static int construct_alloc_key(struct keyring_search_context *ctx,
367			       struct key *dest_keyring,
368			       unsigned long flags,
369			       struct key_user *user,
370			       struct key **_key)
371{
372	struct assoc_array_edit *edit = NULL;
373	struct key *key;
374	key_perm_t perm;
375	key_ref_t key_ref;
376	int ret;
377
378	kenter("%s,%s,,,",
379	       ctx->index_key.type->name, ctx->index_key.description);
380
381	*_key = NULL;
382	mutex_lock(&user->cons_lock);
383
384	perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
385	perm |= KEY_USR_VIEW;
386	if (ctx->index_key.type->read)
387		perm |= KEY_POS_READ;
388	if (ctx->index_key.type == &key_type_keyring ||
389	    ctx->index_key.type->update)
390		perm |= KEY_POS_WRITE;
391
392	key = key_alloc(ctx->index_key.type, ctx->index_key.description,
393			ctx->cred->fsuid, ctx->cred->fsgid, ctx->cred,
394			perm, flags, NULL);
395	if (IS_ERR(key))
396		goto alloc_failed;
397
398	set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
399
400	if (dest_keyring) {
401		ret = __key_link_lock(dest_keyring, &ctx->index_key);
402		if (ret < 0)
403			goto link_lock_failed;
404		ret = __key_link_begin(dest_keyring, &ctx->index_key, &edit);
405		if (ret < 0)
406			goto link_prealloc_failed;
407	}
408
409	/* attach the key to the destination keyring under lock, but we do need
410	 * to do another check just in case someone beat us to it whilst we
411	 * waited for locks */
412	mutex_lock(&key_construction_mutex);
413
414	rcu_read_lock();
415	key_ref = search_process_keyrings_rcu(ctx);
416	rcu_read_unlock();
417	if (!IS_ERR(key_ref))
418		goto key_already_present;
419
420	if (dest_keyring)
421		__key_link(dest_keyring, key, &edit);
422
423	mutex_unlock(&key_construction_mutex);
424	if (dest_keyring)
425		__key_link_end(dest_keyring, &ctx->index_key, edit);
426	mutex_unlock(&user->cons_lock);
427	*_key = key;
428	kleave(" = 0 [%d]", key_serial(key));
429	return 0;
430
431	/* the key is now present - we tell the caller that we found it by
432	 * returning -EINPROGRESS  */
433key_already_present:
434	key_put(key);
435	mutex_unlock(&key_construction_mutex);
436	key = key_ref_to_ptr(key_ref);
437	if (dest_keyring) {
438		ret = __key_link_check_live_key(dest_keyring, key);
439		if (ret == 0)
440			__key_link(dest_keyring, key, &edit);
441		__key_link_end(dest_keyring, &ctx->index_key, edit);
442		if (ret < 0)
443			goto link_check_failed;
444	}
445	mutex_unlock(&user->cons_lock);
446	*_key = key;
447	kleave(" = -EINPROGRESS [%d]", key_serial(key));
448	return -EINPROGRESS;
449
450link_check_failed:
451	mutex_unlock(&user->cons_lock);
452	key_put(key);
453	kleave(" = %d [linkcheck]", ret);
454	return ret;
455
456link_prealloc_failed:
457	__key_link_end(dest_keyring, &ctx->index_key, edit);
458link_lock_failed:
459	mutex_unlock(&user->cons_lock);
460	key_put(key);
461	kleave(" = %d [prelink]", ret);
462	return ret;
463
464alloc_failed:
465	mutex_unlock(&user->cons_lock);
466	kleave(" = %ld", PTR_ERR(key));
467	return PTR_ERR(key);
468}
469
470/*
471 * Commence key construction.
472 */
473static struct key *construct_key_and_link(struct keyring_search_context *ctx,
474					  const char *callout_info,
475					  size_t callout_len,
476					  void *aux,
477					  struct key *dest_keyring,
478					  unsigned long flags)
479{
480	struct key_user *user;
481	struct key *key;
482	int ret;
483
484	kenter("");
485
486	if (ctx->index_key.type == &key_type_keyring)
487		return ERR_PTR(-EPERM);
488
489	ret = construct_get_dest_keyring(&dest_keyring);
490	if (ret)
491		goto error;
492
493	user = key_user_lookup(current_fsuid());
494	if (!user) {
495		ret = -ENOMEM;
496		goto error_put_dest_keyring;
497	}
498
499	ret = construct_alloc_key(ctx, dest_keyring, flags, user, &key);
500	key_user_put(user);
501
502	if (ret == 0) {
503		ret = construct_key(key, callout_info, callout_len, aux,
504				    dest_keyring);
505		if (ret < 0) {
506			kdebug("cons failed");
507			goto construction_failed;
508		}
509	} else if (ret == -EINPROGRESS) {
510		ret = 0;
511	} else {
512		goto error_put_dest_keyring;
513	}
514
515	key_put(dest_keyring);
516	kleave(" = key %d", key_serial(key));
517	return key;
518
519construction_failed:
520	key_negate_and_link(key, key_negative_timeout, NULL, NULL);
521	key_put(key);
522error_put_dest_keyring:
523	key_put(dest_keyring);
524error:
525	kleave(" = %d", ret);
526	return ERR_PTR(ret);
527}
528
529/**
530 * request_key_and_link - Request a key and cache it in a keyring.
531 * @type: The type of key we want.
532 * @description: The searchable description of the key.
533 * @domain_tag: The domain in which the key operates.
534 * @callout_info: The data to pass to the instantiation upcall (or NULL).
535 * @callout_len: The length of callout_info.
536 * @aux: Auxiliary data for the upcall.
537 * @dest_keyring: Where to cache the key.
538 * @flags: Flags to key_alloc().
539 *
540 * A key matching the specified criteria (type, description, domain_tag) is
541 * searched for in the process's keyrings and returned with its usage count
542 * incremented if found.  Otherwise, if callout_info is not NULL, a key will be
543 * allocated and some service (probably in userspace) will be asked to
544 * instantiate it.
545 *
546 * If successfully found or created, the key will be linked to the destination
547 * keyring if one is provided.
548 *
549 * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
550 * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
551 * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
552 * if insufficient key quota was available to create a new key; or -ENOMEM if
553 * insufficient memory was available.
554 *
555 * If the returned key was created, then it may still be under construction,
556 * and wait_for_key_construction() should be used to wait for that to complete.
557 */
558struct key *request_key_and_link(struct key_type *type,
559				 const char *description,
560				 struct key_tag *domain_tag,
561				 const void *callout_info,
562				 size_t callout_len,
563				 void *aux,
564				 struct key *dest_keyring,
565				 unsigned long flags)
566{
567	struct keyring_search_context ctx = {
568		.index_key.type		= type,
569		.index_key.domain_tag	= domain_tag,
570		.index_key.description	= description,
571		.index_key.desc_len	= strlen(description),
572		.cred			= current_cred(),
573		.match_data.cmp		= key_default_cmp,
574		.match_data.raw_data	= description,
575		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
576		.flags			= (KEYRING_SEARCH_DO_STATE_CHECK |
577					   KEYRING_SEARCH_SKIP_EXPIRED |
578					   KEYRING_SEARCH_RECURSE),
579	};
580	struct key *key;
581	key_ref_t key_ref;
582	int ret;
583
584	kenter("%s,%s,%p,%zu,%p,%p,%lx",
585	       ctx.index_key.type->name, ctx.index_key.description,
586	       callout_info, callout_len, aux, dest_keyring, flags);
587
588	if (type->match_preparse) {
589		ret = type->match_preparse(&ctx.match_data);
590		if (ret < 0) {
591			key = ERR_PTR(ret);
592			goto error;
593		}
594	}
595
596	key = check_cached_key(&ctx);
597	if (key)
598		goto error_free;
599
600	/* search all the process keyrings for a key */
601	rcu_read_lock();
602	key_ref = search_process_keyrings_rcu(&ctx);
603	rcu_read_unlock();
604
605	if (!IS_ERR(key_ref)) {
606		if (dest_keyring) {
607			ret = key_task_permission(key_ref, current_cred(),
608						  KEY_NEED_LINK);
609			if (ret < 0) {
610				key_ref_put(key_ref);
611				key = ERR_PTR(ret);
612				goto error_free;
613			}
614		}
615
616		key = key_ref_to_ptr(key_ref);
617		if (dest_keyring) {
618			ret = key_link(dest_keyring, key);
619			if (ret < 0) {
620				key_put(key);
621				key = ERR_PTR(ret);
622				goto error_free;
623			}
624		}
625
626		/* Only cache the key on immediate success */
627		cache_requested_key(key);
628	} else if (PTR_ERR(key_ref) != -EAGAIN) {
629		key = ERR_CAST(key_ref);
630	} else  {
631		/* the search failed, but the keyrings were searchable, so we
632		 * should consult userspace if we can */
633		key = ERR_PTR(-ENOKEY);
634		if (!callout_info)
635			goto error_free;
636
637		key = construct_key_and_link(&ctx, callout_info, callout_len,
638					     aux, dest_keyring, flags);
639	}
640
641error_free:
642	if (type->match_free)
643		type->match_free(&ctx.match_data);
644error:
645	kleave(" = %p", key);
646	return key;
647}
648
649/**
650 * wait_for_key_construction - Wait for construction of a key to complete
651 * @key: The key being waited for.
652 * @intr: Whether to wait interruptibly.
653 *
654 * Wait for a key to finish being constructed.
655 *
656 * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
657 * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
658 * revoked or expired.
659 */
660int wait_for_key_construction(struct key *key, bool intr)
661{
662	int ret;
663
664	ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
665			  intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
666	if (ret)
667		return -ERESTARTSYS;
668	ret = key_read_state(key);
669	if (ret < 0)
670		return ret;
671	return key_validate(key);
672}
673EXPORT_SYMBOL(wait_for_key_construction);
674
675/**
676 * request_key_tag - Request a key and wait for construction
677 * @type: Type of key.
678 * @description: The searchable description of the key.
679 * @domain_tag: The domain in which the key operates.
680 * @callout_info: The data to pass to the instantiation upcall (or NULL).
681 *
682 * As for request_key_and_link() except that it does not add the returned key
683 * to a keyring if found, new keys are always allocated in the user's quota,
684 * the callout_info must be a NUL-terminated string and no auxiliary data can
685 * be passed.
686 *
687 * Furthermore, it then works as wait_for_key_construction() to wait for the
688 * completion of keys undergoing construction with a non-interruptible wait.
689 */
690struct key *request_key_tag(struct key_type *type,
691			    const char *description,
692			    struct key_tag *domain_tag,
693			    const char *callout_info)
694{
695	struct key *key;
696	size_t callout_len = 0;
697	int ret;
698
699	if (callout_info)
700		callout_len = strlen(callout_info);
701	key = request_key_and_link(type, description, domain_tag,
702				   callout_info, callout_len,
703				   NULL, NULL, KEY_ALLOC_IN_QUOTA);
704	if (!IS_ERR(key)) {
705		ret = wait_for_key_construction(key, false);
706		if (ret < 0) {
707			key_put(key);
708			return ERR_PTR(ret);
709		}
710	}
711	return key;
712}
713EXPORT_SYMBOL(request_key_tag);
714
715/**
716 * request_key_with_auxdata - Request a key with auxiliary data for the upcaller
717 * @type: The type of key we want.
718 * @description: The searchable description of the key.
719 * @domain_tag: The domain in which the key operates.
720 * @callout_info: The data to pass to the instantiation upcall (or NULL).
721 * @callout_len: The length of callout_info.
722 * @aux: Auxiliary data for the upcall.
723 *
724 * As for request_key_and_link() except that it does not add the returned key
725 * to a keyring if found and new keys are always allocated in the user's quota.
726 *
727 * Furthermore, it then works as wait_for_key_construction() to wait for the
728 * completion of keys undergoing construction with a non-interruptible wait.
729 */
730struct key *request_key_with_auxdata(struct key_type *type,
731				     const char *description,
732				     struct key_tag *domain_tag,
733				     const void *callout_info,
734				     size_t callout_len,
735				     void *aux)
736{
737	struct key *key;
738	int ret;
739
740	key = request_key_and_link(type, description, domain_tag,
741				   callout_info, callout_len,
742				   aux, NULL, KEY_ALLOC_IN_QUOTA);
743	if (!IS_ERR(key)) {
744		ret = wait_for_key_construction(key, false);
745		if (ret < 0) {
746			key_put(key);
747			return ERR_PTR(ret);
748		}
749	}
750	return key;
751}
752EXPORT_SYMBOL(request_key_with_auxdata);
753
754/**
755 * request_key_rcu - Request key from RCU-read-locked context
756 * @type: The type of key we want.
757 * @description: The name of the key we want.
758 * @domain_tag: The domain in which the key operates.
759 *
760 * Request a key from a context that we may not sleep in (such as RCU-mode
761 * pathwalk).  Keys under construction are ignored.
762 *
763 * Return a pointer to the found key if successful, -ENOKEY if we couldn't find
764 * a key or some other error if the key found was unsuitable or inaccessible.
765 */
766struct key *request_key_rcu(struct key_type *type,
767			    const char *description,
768			    struct key_tag *domain_tag)
769{
770	struct keyring_search_context ctx = {
771		.index_key.type		= type,
772		.index_key.domain_tag	= domain_tag,
773		.index_key.description	= description,
774		.index_key.desc_len	= strlen(description),
775		.cred			= current_cred(),
776		.match_data.cmp		= key_default_cmp,
777		.match_data.raw_data	= description,
778		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
779		.flags			= (KEYRING_SEARCH_DO_STATE_CHECK |
780					   KEYRING_SEARCH_SKIP_EXPIRED),
781	};
782	struct key *key;
783	key_ref_t key_ref;
784
785	kenter("%s,%s", type->name, description);
786
787	key = check_cached_key(&ctx);
788	if (key)
789		return key;
790
791	/* search all the process keyrings for a key */
792	key_ref = search_process_keyrings_rcu(&ctx);
793	if (IS_ERR(key_ref)) {
794		key = ERR_CAST(key_ref);
795		if (PTR_ERR(key_ref) == -EAGAIN)
796			key = ERR_PTR(-ENOKEY);
797	} else {
798		key = key_ref_to_ptr(key_ref);
799		cache_requested_key(key);
800	}
801
802	kleave(" = %p", key);
803	return key;
804}
805EXPORT_SYMBOL(request_key_rcu);

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* Request a key from userspace
  3 *
  4 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
  5 * Written by David Howells (dhowells@redhat.com)
  6 *
  7 * See Documentation/security/keys/request-key.rst
  8 */
  9
 10#include <linux/export.h>
 11#include <linux/sched.h>
 12#include <linux/kmod.h>
 13#include <linux/err.h>
 14#include <linux/keyctl.h>
 15#include <linux/slab.h>
 16#include <net/net_namespace.h>
 17#include "internal.h"
 18#include <keys/request_key_auth-type.h>
 19
 20#define key_negative_timeout	60	/* default timeout on a negative key's existence */
 21
 22static struct key *check_cached_key(struct keyring_search_context *ctx)
 23{
 24#ifdef CONFIG_KEYS_REQUEST_CACHE
 25	struct key *key = current->cached_requested_key;
 26
 27	if (key &&
 28	    ctx->match_data.cmp(key, &ctx->match_data) &&
 29	    !(key->flags & ((1 << KEY_FLAG_INVALIDATED) |
 30			    (1 << KEY_FLAG_REVOKED))))
 31		return key_get(key);
 32#endif
 33	return NULL;
 34}
 35
 36static void cache_requested_key(struct key *key)
 37{
 38#ifdef CONFIG_KEYS_REQUEST_CACHE
 39	struct task_struct *t = current;
 40
 41	key_put(t->cached_requested_key);
 42	t->cached_requested_key = key_get(key);
 43	set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
 44#endif
 45}
 46
 47/**
 48 * complete_request_key - Complete the construction of a key.
 49 * @authkey: The authorisation key.
 50 * @error: The success or failute of the construction.
 51 *
 52 * Complete the attempt to construct a key.  The key will be negated
 53 * if an error is indicated.  The authorisation key will be revoked
 54 * unconditionally.
 55 */
 56void complete_request_key(struct key *authkey, int error)
 57{
 58	struct request_key_auth *rka = get_request_key_auth(authkey);
 59	struct key *key = rka->target_key;
 60
 61	kenter("%d{%d},%d", authkey->serial, key->serial, error);
 62
 63	if (error < 0)
 64		key_negate_and_link(key, key_negative_timeout, NULL, authkey);
 65	else
 66		key_revoke(authkey);
 67}
 68EXPORT_SYMBOL(complete_request_key);
 69
 70/*
 71 * Initialise a usermode helper that is going to have a specific session
 72 * keyring.
 73 *
 74 * This is called in context of freshly forked kthread before kernel_execve(),
 75 * so we can simply install the desired session_keyring at this point.
 76 */
 77static int umh_keys_init(struct subprocess_info *info, struct cred *cred)
 78{
 79	struct key *keyring = info->data;
 80
 81	return install_session_keyring_to_cred(cred, keyring);
 82}
 83
 84/*
 85 * Clean up a usermode helper with session keyring.
 86 */
 87static void umh_keys_cleanup(struct subprocess_info *info)
 88{
 89	struct key *keyring = info->data;
 90	key_put(keyring);
 91}
 92
 93/*
 94 * Call a usermode helper with a specific session keyring.
 95 */
 96static int call_usermodehelper_keys(const char *path, char **argv, char **envp,
 97					struct key *session_keyring, int wait)
 98{
 99	struct subprocess_info *info;
100
101	info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL,
102					  umh_keys_init, umh_keys_cleanup,
103					  session_keyring);
104	if (!info)
105		return -ENOMEM;
106
107	key_get(session_keyring);
108	return call_usermodehelper_exec(info, wait);
109}
110
111/*
112 * Request userspace finish the construction of a key
113 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
114 */
115static int call_sbin_request_key(struct key *authkey, void *aux)
116{
117	static char const request_key[] = "/sbin/request-key";
118	struct request_key_auth *rka = get_request_key_auth(authkey);
119	const struct cred *cred = current_cred();
120	key_serial_t prkey, sskey;
121	struct key *key = rka->target_key, *keyring, *session, *user_session;
122	char *argv[9], *envp[3], uid_str[12], gid_str[12];
123	char key_str[12], keyring_str[3][12];
124	char desc[20];
125	int ret, i;
126
127	kenter("{%d},{%d},%s", key->serial, authkey->serial, rka->op);
128
129	ret = look_up_user_keyrings(NULL, &user_session);
130	if (ret < 0)
131		goto error_us;
132
133	/* allocate a new session keyring */
134	sprintf(desc, "_req.%u", key->serial);
135
136	cred = get_current_cred();
137	keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
138				KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
139				KEY_ALLOC_QUOTA_OVERRUN, NULL, NULL);
140	put_cred(cred);
141	if (IS_ERR(keyring)) {
142		ret = PTR_ERR(keyring);
143		goto error_alloc;
144	}
145
146	/* attach the auth key to the session keyring */
147	ret = key_link(keyring, authkey);
148	if (ret < 0)
149		goto error_link;
150
151	/* record the UID and GID */
152	sprintf(uid_str, "%d", from_kuid(&init_user_ns, cred->fsuid));
153	sprintf(gid_str, "%d", from_kgid(&init_user_ns, cred->fsgid));
154
155	/* we say which key is under construction */
156	sprintf(key_str, "%d", key->serial);
157
158	/* we specify the process's default keyrings */
159	sprintf(keyring_str[0], "%d",
160		cred->thread_keyring ? cred->thread_keyring->serial : 0);
161
162	prkey = 0;
163	if (cred->process_keyring)
164		prkey = cred->process_keyring->serial;
165	sprintf(keyring_str[1], "%d", prkey);
166
167	session = cred->session_keyring;
168	if (!session)
169		session = user_session;
170	sskey = session->serial;
171
172	sprintf(keyring_str[2], "%d", sskey);
173
174	/* set up a minimal environment */
175	i = 0;
176	envp[i++] = "HOME=/";
177	envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
178	envp[i] = NULL;
179
180	/* set up the argument list */
181	i = 0;
182	argv[i++] = (char *)request_key;
183	argv[i++] = (char *)rka->op;
184	argv[i++] = key_str;
185	argv[i++] = uid_str;
186	argv[i++] = gid_str;
187	argv[i++] = keyring_str[0];
188	argv[i++] = keyring_str[1];
189	argv[i++] = keyring_str[2];
190	argv[i] = NULL;
191
192	/* do it */
193	ret = call_usermodehelper_keys(request_key, argv, envp, keyring,
194				       UMH_WAIT_PROC);
195	kdebug("usermode -> 0x%x", ret);
196	if (ret >= 0) {
197		/* ret is the exit/wait code */
198		if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
199		    key_validate(key) < 0)
200			ret = -ENOKEY;
201		else
202			/* ignore any errors from userspace if the key was
203			 * instantiated */
204			ret = 0;
205	}
206
207error_link:
208	key_put(keyring);
209
210error_alloc:
211	key_put(user_session);
212error_us:
213	complete_request_key(authkey, ret);
214	kleave(" = %d", ret);
215	return ret;
216}
217
218/*
219 * Call out to userspace for key construction.
220 *
221 * Program failure is ignored in favour of key status.
222 */
223static int construct_key(struct key *key, const void *callout_info,
224			 size_t callout_len, void *aux,
225			 struct key *dest_keyring)
226{
227	request_key_actor_t actor;
228	struct key *authkey;
229	int ret;
230
231	kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
232
233	/* allocate an authorisation key */
234	authkey = request_key_auth_new(key, "create", callout_info, callout_len,
235				       dest_keyring);
236	if (IS_ERR(authkey))
237		return PTR_ERR(authkey);
238
239	/* Make the call */
240	actor = call_sbin_request_key;
241	if (key->type->request_key)
242		actor = key->type->request_key;
243
244	ret = actor(authkey, aux);
245
246	/* check that the actor called complete_request_key() prior to
247	 * returning an error */
248	WARN_ON(ret < 0 &&
249		!test_bit(KEY_FLAG_INVALIDATED, &authkey->flags));
250
251	key_put(authkey);
252	kleave(" = %d", ret);
253	return ret;
254}
255
256/*
257 * Get the appropriate destination keyring for the request.
258 *
259 * The keyring selected is returned with an extra reference upon it which the
260 * caller must release.
261 */
262static int construct_get_dest_keyring(struct key **_dest_keyring)
263{
264	struct request_key_auth *rka;
265	const struct cred *cred = current_cred();
266	struct key *dest_keyring = *_dest_keyring, *authkey;
267	int ret;
268
269	kenter("%p", dest_keyring);
270
271	/* find the appropriate keyring */
272	if (dest_keyring) {
273		/* the caller supplied one */
274		key_get(dest_keyring);
275	} else {
276		bool do_perm_check = true;
277
278		/* use a default keyring; falling through the cases until we
279		 * find one that we actually have */
280		switch (cred->jit_keyring) {
281		case KEY_REQKEY_DEFL_DEFAULT:
282		case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
283			if (cred->request_key_auth) {
284				authkey = cred->request_key_auth;
285				down_read(&authkey->sem);
286				rka = get_request_key_auth(authkey);
287				if (!test_bit(KEY_FLAG_REVOKED,
288					      &authkey->flags))
289					dest_keyring =
290						key_get(rka->dest_keyring);
291				up_read(&authkey->sem);
292				if (dest_keyring) {
293					do_perm_check = false;
294					break;
295				}
296			}
297
298			fallthrough;
299		case KEY_REQKEY_DEFL_THREAD_KEYRING:
300			dest_keyring = key_get(cred->thread_keyring);
301			if (dest_keyring)
302				break;
303
304			fallthrough;
305		case KEY_REQKEY_DEFL_PROCESS_KEYRING:
306			dest_keyring = key_get(cred->process_keyring);
307			if (dest_keyring)
308				break;
309
310			fallthrough;
311		case KEY_REQKEY_DEFL_SESSION_KEYRING:
312			dest_keyring = key_get(cred->session_keyring);
313
314			if (dest_keyring)
315				break;
316
317			fallthrough;
318		case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
319			ret = look_up_user_keyrings(NULL, &dest_keyring);
320			if (ret < 0)
321				return ret;
322			break;
323
324		case KEY_REQKEY_DEFL_USER_KEYRING:
325			ret = look_up_user_keyrings(&dest_keyring, NULL);
326			if (ret < 0)
327				return ret;
328			break;
329
330		case KEY_REQKEY_DEFL_GROUP_KEYRING:
331		default:
332			BUG();
333		}
334
335		/*
336		 * Require Write permission on the keyring.  This is essential
337		 * because the default keyring may be the session keyring, and
338		 * joining a keyring only requires Search permission.
339		 *
340		 * However, this check is skipped for the "requestor keyring" so
341		 * that /sbin/request-key can itself use request_key() to add
342		 * keys to the original requestor's destination keyring.
343		 */
344		if (dest_keyring && do_perm_check) {
345			ret = key_permission(make_key_ref(dest_keyring, 1),
346					     KEY_NEED_WRITE);
347			if (ret) {
348				key_put(dest_keyring);
349				return ret;
350			}
351		}
352	}
353
354	*_dest_keyring = dest_keyring;
355	kleave(" [dk %d]", key_serial(dest_keyring));
356	return 0;
357}
358
359/*
360 * Allocate a new key in under-construction state and attempt to link it in to
361 * the requested keyring.
362 *
363 * May return a key that's already under construction instead if there was a
364 * race between two thread calling request_key().
365 */
366static int construct_alloc_key(struct keyring_search_context *ctx,
367			       struct key *dest_keyring,
368			       unsigned long flags,
369			       struct key_user *user,
370			       struct key **_key)
371{
372	struct assoc_array_edit *edit = NULL;
373	struct key *key;
374	key_perm_t perm;
375	key_ref_t key_ref;
376	int ret;
377
378	kenter("%s,%s,,,",
379	       ctx->index_key.type->name, ctx->index_key.description);
380
381	*_key = NULL;
382	mutex_lock(&user->cons_lock);
383
384	perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
385	perm |= KEY_USR_VIEW;
386	if (ctx->index_key.type->read)
387		perm |= KEY_POS_READ;
388	if (ctx->index_key.type == &key_type_keyring ||
389	    ctx->index_key.type->update)
390		perm |= KEY_POS_WRITE;
391
392	key = key_alloc(ctx->index_key.type, ctx->index_key.description,
393			ctx->cred->fsuid, ctx->cred->fsgid, ctx->cred,
394			perm, flags, NULL);
395	if (IS_ERR(key))
396		goto alloc_failed;
397
398	set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
399
400	if (dest_keyring) {
401		ret = __key_link_lock(dest_keyring, &ctx->index_key);
402		if (ret < 0)
403			goto link_lock_failed;
404		ret = __key_link_begin(dest_keyring, &ctx->index_key, &edit);
405		if (ret < 0)
406			goto link_prealloc_failed;
407	}
408
409	/* attach the key to the destination keyring under lock, but we do need
410	 * to do another check just in case someone beat us to it whilst we
411	 * waited for locks */
412	mutex_lock(&key_construction_mutex);
413
414	rcu_read_lock();
415	key_ref = search_process_keyrings_rcu(ctx);
416	rcu_read_unlock();
417	if (!IS_ERR(key_ref))
418		goto key_already_present;
419
420	if (dest_keyring)
421		__key_link(dest_keyring, key, &edit);
422
423	mutex_unlock(&key_construction_mutex);
424	if (dest_keyring)
425		__key_link_end(dest_keyring, &ctx->index_key, edit);
426	mutex_unlock(&user->cons_lock);
427	*_key = key;
428	kleave(" = 0 [%d]", key_serial(key));
429	return 0;
430
431	/* the key is now present - we tell the caller that we found it by
432	 * returning -EINPROGRESS  */
433key_already_present:
434	key_put(key);
435	mutex_unlock(&key_construction_mutex);
436	key = key_ref_to_ptr(key_ref);
437	if (dest_keyring) {
438		ret = __key_link_check_live_key(dest_keyring, key);
439		if (ret == 0)
440			__key_link(dest_keyring, key, &edit);
441		__key_link_end(dest_keyring, &ctx->index_key, edit);
442		if (ret < 0)
443			goto link_check_failed;
444	}
445	mutex_unlock(&user->cons_lock);
446	*_key = key;
447	kleave(" = -EINPROGRESS [%d]", key_serial(key));
448	return -EINPROGRESS;
449
450link_check_failed:
451	mutex_unlock(&user->cons_lock);
452	key_put(key);
453	kleave(" = %d [linkcheck]", ret);
454	return ret;
455
456link_prealloc_failed:
457	__key_link_end(dest_keyring, &ctx->index_key, edit);
458link_lock_failed:
459	mutex_unlock(&user->cons_lock);
460	key_put(key);
461	kleave(" = %d [prelink]", ret);
462	return ret;
463
464alloc_failed:
465	mutex_unlock(&user->cons_lock);
466	kleave(" = %ld", PTR_ERR(key));
467	return PTR_ERR(key);
468}
469
470/*
471 * Commence key construction.
472 */
473static struct key *construct_key_and_link(struct keyring_search_context *ctx,
474					  const char *callout_info,
475					  size_t callout_len,
476					  void *aux,
477					  struct key *dest_keyring,
478					  unsigned long flags)
479{
480	struct key_user *user;
481	struct key *key;
482	int ret;
483
484	kenter("");
485
486	if (ctx->index_key.type == &key_type_keyring)
487		return ERR_PTR(-EPERM);
488
489	ret = construct_get_dest_keyring(&dest_keyring);
490	if (ret)
491		goto error;
492
493	user = key_user_lookup(current_fsuid());
494	if (!user) {
495		ret = -ENOMEM;
496		goto error_put_dest_keyring;
497	}
498
499	ret = construct_alloc_key(ctx, dest_keyring, flags, user, &key);
500	key_user_put(user);
501
502	if (ret == 0) {
503		ret = construct_key(key, callout_info, callout_len, aux,
504				    dest_keyring);
505		if (ret < 0) {
506			kdebug("cons failed");
507			goto construction_failed;
508		}
509	} else if (ret == -EINPROGRESS) {
510		ret = 0;
511	} else {
512		goto error_put_dest_keyring;
513	}
514
515	key_put(dest_keyring);
516	kleave(" = key %d", key_serial(key));
517	return key;
518
519construction_failed:
520	key_negate_and_link(key, key_negative_timeout, NULL, NULL);
521	key_put(key);
522error_put_dest_keyring:
523	key_put(dest_keyring);
524error:
525	kleave(" = %d", ret);
526	return ERR_PTR(ret);
527}
528
529/**
530 * request_key_and_link - Request a key and cache it in a keyring.
531 * @type: The type of key we want.
532 * @description: The searchable description of the key.
533 * @domain_tag: The domain in which the key operates.
534 * @callout_info: The data to pass to the instantiation upcall (or NULL).
535 * @callout_len: The length of callout_info.
536 * @aux: Auxiliary data for the upcall.
537 * @dest_keyring: Where to cache the key.
538 * @flags: Flags to key_alloc().
539 *
540 * A key matching the specified criteria (type, description, domain_tag) is
541 * searched for in the process's keyrings and returned with its usage count
542 * incremented if found.  Otherwise, if callout_info is not NULL, a key will be
543 * allocated and some service (probably in userspace) will be asked to
544 * instantiate it.
545 *
546 * If successfully found or created, the key will be linked to the destination
547 * keyring if one is provided.
548 *
549 * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
550 * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
551 * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
552 * if insufficient key quota was available to create a new key; or -ENOMEM if
553 * insufficient memory was available.
554 *
555 * If the returned key was created, then it may still be under construction,
556 * and wait_for_key_construction() should be used to wait for that to complete.
557 */
558struct key *request_key_and_link(struct key_type *type,
559				 const char *description,
560				 struct key_tag *domain_tag,
561				 const void *callout_info,
562				 size_t callout_len,
563				 void *aux,
564				 struct key *dest_keyring,
565				 unsigned long flags)
566{
567	struct keyring_search_context ctx = {
568		.index_key.type		= type,
569		.index_key.domain_tag	= domain_tag,
570		.index_key.description	= description,
571		.index_key.desc_len	= strlen(description),
572		.cred			= current_cred(),
573		.match_data.cmp		= key_default_cmp,
574		.match_data.raw_data	= description,
575		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
576		.flags			= (KEYRING_SEARCH_DO_STATE_CHECK |
577					   KEYRING_SEARCH_SKIP_EXPIRED |
578					   KEYRING_SEARCH_RECURSE),
579	};
580	struct key *key;
581	key_ref_t key_ref;
582	int ret;
583
584	kenter("%s,%s,%p,%zu,%p,%p,%lx",
585	       ctx.index_key.type->name, ctx.index_key.description,
586	       callout_info, callout_len, aux, dest_keyring, flags);
587
588	if (type->match_preparse) {
589		ret = type->match_preparse(&ctx.match_data);
590		if (ret < 0) {
591			key = ERR_PTR(ret);
592			goto error;
593		}
594	}
595
596	key = check_cached_key(&ctx);
597	if (key)
598		goto error_free;
599
600	/* search all the process keyrings for a key */
601	rcu_read_lock();
602	key_ref = search_process_keyrings_rcu(&ctx);
603	rcu_read_unlock();
604
605	if (!IS_ERR(key_ref)) {
606		if (dest_keyring) {
607			ret = key_task_permission(key_ref, current_cred(),
608						  KEY_NEED_LINK);
609			if (ret < 0) {
610				key_ref_put(key_ref);
611				key = ERR_PTR(ret);
612				goto error_free;
613			}
614		}
615
616		key = key_ref_to_ptr(key_ref);
617		if (dest_keyring) {
618			ret = key_link(dest_keyring, key);
619			if (ret < 0) {
620				key_put(key);
621				key = ERR_PTR(ret);
622				goto error_free;
623			}
624		}
625
626		/* Only cache the key on immediate success */
627		cache_requested_key(key);
628	} else if (PTR_ERR(key_ref) != -EAGAIN) {
629		key = ERR_CAST(key_ref);
630	} else  {
631		/* the search failed, but the keyrings were searchable, so we
632		 * should consult userspace if we can */
633		key = ERR_PTR(-ENOKEY);
634		if (!callout_info)
635			goto error_free;
636
637		key = construct_key_and_link(&ctx, callout_info, callout_len,
638					     aux, dest_keyring, flags);
639	}
640
641error_free:
642	if (type->match_free)
643		type->match_free(&ctx.match_data);
644error:
645	kleave(" = %p", key);
646	return key;
647}
648
649/**
650 * wait_for_key_construction - Wait for construction of a key to complete
651 * @key: The key being waited for.
652 * @intr: Whether to wait interruptibly.
653 *
654 * Wait for a key to finish being constructed.
655 *
656 * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
657 * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
658 * revoked or expired.
659 */
660int wait_for_key_construction(struct key *key, bool intr)
661{
662	int ret;
663
664	ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
665			  intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
666	if (ret)
667		return -ERESTARTSYS;
668	ret = key_read_state(key);
669	if (ret < 0)
670		return ret;
671	return key_validate(key);
672}
673EXPORT_SYMBOL(wait_for_key_construction);
674
675/**
676 * request_key_tag - Request a key and wait for construction
677 * @type: Type of key.
678 * @description: The searchable description of the key.
679 * @domain_tag: The domain in which the key operates.
680 * @callout_info: The data to pass to the instantiation upcall (or NULL).
681 *
682 * As for request_key_and_link() except that it does not add the returned key
683 * to a keyring if found, new keys are always allocated in the user's quota,
684 * the callout_info must be a NUL-terminated string and no auxiliary data can
685 * be passed.
686 *
687 * Furthermore, it then works as wait_for_key_construction() to wait for the
688 * completion of keys undergoing construction with a non-interruptible wait.
689 */
690struct key *request_key_tag(struct key_type *type,
691			    const char *description,
692			    struct key_tag *domain_tag,
693			    const char *callout_info)
694{
695	struct key *key;
696	size_t callout_len = 0;
697	int ret;
698
699	if (callout_info)
700		callout_len = strlen(callout_info);
701	key = request_key_and_link(type, description, domain_tag,
702				   callout_info, callout_len,
703				   NULL, NULL, KEY_ALLOC_IN_QUOTA);
704	if (!IS_ERR(key)) {
705		ret = wait_for_key_construction(key, false);
706		if (ret < 0) {
707			key_put(key);
708			return ERR_PTR(ret);
709		}
710	}
711	return key;
712}
713EXPORT_SYMBOL(request_key_tag);
714
715/**
716 * request_key_with_auxdata - Request a key with auxiliary data for the upcaller
717 * @type: The type of key we want.
718 * @description: The searchable description of the key.
719 * @domain_tag: The domain in which the key operates.
720 * @callout_info: The data to pass to the instantiation upcall (or NULL).
721 * @callout_len: The length of callout_info.
722 * @aux: Auxiliary data for the upcall.
723 *
724 * As for request_key_and_link() except that it does not add the returned key
725 * to a keyring if found and new keys are always allocated in the user's quota.
726 *
727 * Furthermore, it then works as wait_for_key_construction() to wait for the
728 * completion of keys undergoing construction with a non-interruptible wait.
729 */
730struct key *request_key_with_auxdata(struct key_type *type,
731				     const char *description,
732				     struct key_tag *domain_tag,
733				     const void *callout_info,
734				     size_t callout_len,
735				     void *aux)
736{
737	struct key *key;
738	int ret;
739
740	key = request_key_and_link(type, description, domain_tag,
741				   callout_info, callout_len,
742				   aux, NULL, KEY_ALLOC_IN_QUOTA);
743	if (!IS_ERR(key)) {
744		ret = wait_for_key_construction(key, false);
745		if (ret < 0) {
746			key_put(key);
747			return ERR_PTR(ret);
748		}
749	}
750	return key;
751}
752EXPORT_SYMBOL(request_key_with_auxdata);
753
754/**
755 * request_key_rcu - Request key from RCU-read-locked context
756 * @type: The type of key we want.
757 * @description: The name of the key we want.
758 * @domain_tag: The domain in which the key operates.
759 *
760 * Request a key from a context that we may not sleep in (such as RCU-mode
761 * pathwalk).  Keys under construction are ignored.
762 *
763 * Return a pointer to the found key if successful, -ENOKEY if we couldn't find
764 * a key or some other error if the key found was unsuitable or inaccessible.
765 */
766struct key *request_key_rcu(struct key_type *type,
767			    const char *description,
768			    struct key_tag *domain_tag)
769{
770	struct keyring_search_context ctx = {
771		.index_key.type		= type,
772		.index_key.domain_tag	= domain_tag,
773		.index_key.description	= description,
774		.index_key.desc_len	= strlen(description),
775		.cred			= current_cred(),
776		.match_data.cmp		= key_default_cmp,
777		.match_data.raw_data	= description,
778		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
779		.flags			= (KEYRING_SEARCH_DO_STATE_CHECK |
780					   KEYRING_SEARCH_SKIP_EXPIRED),
781	};
782	struct key *key;
783	key_ref_t key_ref;
784
785	kenter("%s,%s", type->name, description);
786
787	key = check_cached_key(&ctx);
788	if (key)
789		return key;
790
791	/* search all the process keyrings for a key */
792	key_ref = search_process_keyrings_rcu(&ctx);
793	if (IS_ERR(key_ref)) {
794		key = ERR_CAST(key_ref);
795		if (PTR_ERR(key_ref) == -EAGAIN)
796			key = ERR_PTR(-ENOKEY);
797	} else {
798		key = key_ref_to_ptr(key_ref);
799		cache_requested_key(key);
800	}
801
802	kleave(" = %p", key);
803	return key;
804}
805EXPORT_SYMBOL(request_key_rcu);