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 
check_cached_key(struct keyring_search_context * ctx)22 static 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 
cache_requested_key(struct key * key)36 static 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  */
complete_request_key(struct key * authkey,int error)56 void 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 }
68 EXPORT_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  */
umh_keys_init(struct subprocess_info * info,struct cred * cred)77 static 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  */
umh_keys_cleanup(struct subprocess_info * info)87 static 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  */
call_usermodehelper_keys(const char * path,char ** argv,char ** envp,struct key * session_keyring,int wait)96 static 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  */
call_sbin_request_key(struct key * authkey,void * aux)115 static 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 
207 error_link:
208 	key_put(keyring);
209 
210 error_alloc:
211 	key_put(user_session);
212 error_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  */
construct_key(struct key * key,const void * callout_info,size_t callout_len,void * aux,struct key * dest_keyring)223 static 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  */
construct_get_dest_keyring(struct key ** _dest_keyring)262 static 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  */
construct_alloc_key(struct keyring_search_context * ctx,struct key * dest_keyring,unsigned long flags,struct key_user * user,struct key ** _key)366 static 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  */
433 key_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 
450 link_check_failed:
451 	mutex_unlock(&user->cons_lock);
452 	key_put(key);
453 	kleave(" = %d [linkcheck]", ret);
454 	return ret;
455 
456 link_prealloc_failed:
457 	__key_link_end(dest_keyring, &ctx->index_key, edit);
458 link_lock_failed:
459 	mutex_unlock(&user->cons_lock);
460 	key_put(key);
461 	kleave(" = %d [prelink]", ret);
462 	return ret;
463 
464 alloc_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  */
construct_key_and_link(struct keyring_search_context * ctx,const char * callout_info,size_t callout_len,void * aux,struct key * dest_keyring,unsigned long flags)473 static 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 
519 construction_failed:
520 	key_negate_and_link(key, key_negative_timeout, NULL, NULL);
521 	key_put(key);
522 error_put_dest_keyring:
523 	key_put(dest_keyring);
524 error:
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  */
request_key_and_link(struct key_type * type,const char * description,struct key_tag * domain_tag,const void * callout_info,size_t callout_len,void * aux,struct key * dest_keyring,unsigned long flags)558 struct 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 
641 error_free:
642 	if (type->match_free)
643 		type->match_free(&ctx.match_data);
644 error:
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  */
wait_for_key_construction(struct key * key,bool intr)660 int 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 }
673 EXPORT_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  */
request_key_tag(struct key_type * type,const char * description,struct key_tag * domain_tag,const char * callout_info)690 struct 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 }
713 EXPORT_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  */
request_key_with_auxdata(struct key_type * type,const char * description,struct key_tag * domain_tag,const void * callout_info,size_t callout_len,void * aux)730 struct 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 }
752 EXPORT_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  */
request_key_rcu(struct key_type * type,const char * description,struct key_tag * domain_tag)766 struct 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 }
805 EXPORT_SYMBOL(request_key_rcu);
806