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
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
36 static void cache_requested_key(struct key *key)
37 {
38 #ifdef CONFIG_KEYS_REQUEST_CACHE
39 struct task_struct *t = current;
40
41 /* Do not cache key if it is a kernel thread */
42 if (!(t->flags & PF_KTHREAD)) {
43 key_put(t->cached_requested_key);
44 t->cached_requested_key = key_get(key);
45 set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
46 }
47 #endif
48 }
49
50 /**
51 * complete_request_key - Complete the construction of a key.
52 * @authkey: The authorisation key.
53 * @error: The success or failute of the construction.
54 *
55 * Complete the attempt to construct a key. The key will be negated
56 * if an error is indicated. The authorisation key will be revoked
57 * unconditionally.
58 */
59 void complete_request_key(struct key *authkey, int error)
60 {
61 struct request_key_auth *rka = get_request_key_auth(authkey);
62 struct key *key = rka->target_key;
63
64 kenter("%d{%d},%d", authkey->serial, key->serial, error);
65
66 if (error < 0)
67 key_negate_and_link(key, key_negative_timeout, NULL, authkey);
68 else
69 key_revoke(authkey);
70 }
71 EXPORT_SYMBOL(complete_request_key);
72
73 /*
74 * Initialise a usermode helper that is going to have a specific session
75 * keyring.
76 *
77 * This is called in context of freshly forked kthread before kernel_execve(),
78 * so we can simply install the desired session_keyring at this point.
79 */
80 static int umh_keys_init(struct subprocess_info *info, struct cred *cred)
81 {
82 struct key *keyring = info->data;
83
84 return install_session_keyring_to_cred(cred, keyring);
85 }
86
87 /*
88 * Clean up a usermode helper with session keyring.
89 */
90 static void umh_keys_cleanup(struct subprocess_info *info)
91 {
92 struct key *keyring = info->data;
93 key_put(keyring);
94 }
95
96 /*
97 * Call a usermode helper with a specific session keyring.
98 */
99 static int call_usermodehelper_keys(const char *path, char **argv, char **envp,
100 struct key *session_keyring, int wait)
101 {
102 struct subprocess_info *info;
103
104 info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL,
105 umh_keys_init, umh_keys_cleanup,
106 session_keyring);
107 if (!info)
108 return -ENOMEM;
109
110 key_get(session_keyring);
111 return call_usermodehelper_exec(info, wait);
112 }
113
114 /*
115 * Request userspace finish the construction of a key
116 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
117 */
118 static int call_sbin_request_key(struct key *authkey, void *aux)
119 {
120 static char const request_key[] = "/sbin/request-key";
121 struct request_key_auth *rka = get_request_key_auth(authkey);
122 const struct cred *cred = current_cred();
123 key_serial_t prkey, sskey;
124 struct key *key = rka->target_key, *keyring, *session, *user_session;
125 char *argv[9], *envp[3], uid_str[12], gid_str[12];
126 char key_str[12], keyring_str[3][12];
127 char desc[20];
128 int ret, i;
129
130 kenter("{%d},{%d},%s", key->serial, authkey->serial, rka->op);
131
132 ret = look_up_user_keyrings(NULL, &user_session);
133 if (ret < 0)
134 goto error_us;
135
136 /* allocate a new session keyring */
137 sprintf(desc, "_req.%u", key->serial);
138
139 cred = get_current_cred();
140 keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
141 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
142 KEY_ALLOC_QUOTA_OVERRUN, NULL, NULL);
143 put_cred(cred);
144 if (IS_ERR(keyring)) {
145 ret = PTR_ERR(keyring);
146 goto error_alloc;
147 }
148
149 /* attach the auth key to the session keyring */
150 ret = key_link(keyring, authkey);
151 if (ret < 0)
152 goto error_link;
153
154 /* record the UID and GID */
155 sprintf(uid_str, "%d", from_kuid(&init_user_ns, cred->fsuid));
156 sprintf(gid_str, "%d", from_kgid(&init_user_ns, cred->fsgid));
157
158 /* we say which key is under construction */
159 sprintf(key_str, "%d", key->serial);
160
161 /* we specify the process's default keyrings */
162 sprintf(keyring_str[0], "%d",
163 cred->thread_keyring ? cred->thread_keyring->serial : 0);
164
165 prkey = 0;
166 if (cred->process_keyring)
167 prkey = cred->process_keyring->serial;
168 sprintf(keyring_str[1], "%d", prkey);
169
170 session = cred->session_keyring;
171 if (!session)
172 session = user_session;
173 sskey = session->serial;
174
175 sprintf(keyring_str[2], "%d", sskey);
176
177 /* set up a minimal environment */
178 i = 0;
179 envp[i++] = "HOME=/";
180 envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
181 envp[i] = NULL;
182
183 /* set up the argument list */
184 i = 0;
185 argv[i++] = (char *)request_key;
186 argv[i++] = (char *)rka->op;
187 argv[i++] = key_str;
188 argv[i++] = uid_str;
189 argv[i++] = gid_str;
190 argv[i++] = keyring_str[0];
191 argv[i++] = keyring_str[1];
192 argv[i++] = keyring_str[2];
193 argv[i] = NULL;
194
195 /* do it */
196 ret = call_usermodehelper_keys(request_key, argv, envp, keyring,
197 UMH_WAIT_PROC);
198 kdebug("usermode -> 0x%x", ret);
199 if (ret >= 0) {
200 /* ret is the exit/wait code */
201 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
202 key_validate(key) < 0)
203 ret = -ENOKEY;
204 else
205 /* ignore any errors from userspace if the key was
206 * instantiated */
207 ret = 0;
208 }
209
210 error_link:
211 key_put(keyring);
212
213 error_alloc:
214 key_put(user_session);
215 error_us:
216 complete_request_key(authkey, ret);
217 kleave(" = %d", ret);
218 return ret;
219 }
220
221 /*
222 * Call out to userspace for key construction.
223 *
224 * Program failure is ignored in favour of key status.
225 */
226 static int construct_key(struct key *key, const void *callout_info,
227 size_t callout_len, void *aux,
228 struct key *dest_keyring)
229 {
230 request_key_actor_t actor;
231 struct key *authkey;
232 int ret;
233
234 kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
235
236 /* allocate an authorisation key */
237 authkey = request_key_auth_new(key, "create", callout_info, callout_len,
238 dest_keyring);
239 if (IS_ERR(authkey))
240 return PTR_ERR(authkey);
241
242 /* Make the call */
243 actor = call_sbin_request_key;
244 if (key->type->request_key)
245 actor = key->type->request_key;
246
247 ret = actor(authkey, aux);
248
249 /* check that the actor called complete_request_key() prior to
250 * returning an error */
251 WARN_ON(ret < 0 &&
252 !test_bit(KEY_FLAG_INVALIDATED, &authkey->flags));
253
254 key_put(authkey);
255 kleave(" = %d", ret);
256 return ret;
257 }
258
259 /*
260 * Get the appropriate destination keyring for the request.
261 *
262 * The keyring selected is returned with an extra reference upon it which the
263 * caller must release.
264 */
265 static int construct_get_dest_keyring(struct key **_dest_keyring)
266 {
267 struct request_key_auth *rka;
268 const struct cred *cred = current_cred();
269 struct key *dest_keyring = *_dest_keyring, *authkey;
270 int ret;
271
272 kenter("%p", dest_keyring);
273
274 /* find the appropriate keyring */
275 if (dest_keyring) {
276 /* the caller supplied one */
277 key_get(dest_keyring);
278 } else {
279 bool do_perm_check = true;
280
281 /* use a default keyring; falling through the cases until we
282 * find one that we actually have */
283 switch (cred->jit_keyring) {
284 case KEY_REQKEY_DEFL_DEFAULT:
285 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
286 if (cred->request_key_auth) {
287 authkey = cred->request_key_auth;
288 down_read(&authkey->sem);
289 rka = get_request_key_auth(authkey);
290 if (!test_bit(KEY_FLAG_REVOKED,
291 &authkey->flags))
292 dest_keyring =
293 key_get(rka->dest_keyring);
294 up_read(&authkey->sem);
295 if (dest_keyring) {
296 do_perm_check = false;
297 break;
298 }
299 }
300
301 fallthrough;
302 case KEY_REQKEY_DEFL_THREAD_KEYRING:
303 dest_keyring = key_get(cred->thread_keyring);
304 if (dest_keyring)
305 break;
306
307 fallthrough;
308 case KEY_REQKEY_DEFL_PROCESS_KEYRING:
309 dest_keyring = key_get(cred->process_keyring);
310 if (dest_keyring)
311 break;
312
313 fallthrough;
314 case KEY_REQKEY_DEFL_SESSION_KEYRING:
315 dest_keyring = key_get(cred->session_keyring);
316
317 if (dest_keyring)
318 break;
319
320 fallthrough;
321 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
322 ret = look_up_user_keyrings(NULL, &dest_keyring);
323 if (ret < 0)
324 return ret;
325 break;
326
327 case KEY_REQKEY_DEFL_USER_KEYRING:
328 ret = look_up_user_keyrings(&dest_keyring, NULL);
329 if (ret < 0)
330 return ret;
331 break;
332
333 case KEY_REQKEY_DEFL_GROUP_KEYRING:
334 default:
335 BUG();
336 }
337
338 /*
339 * Require Write permission on the keyring. This is essential
340 * because the default keyring may be the session keyring, and
341 * joining a keyring only requires Search permission.
342 *
343 * However, this check is skipped for the "requestor keyring" so
344 * that /sbin/request-key can itself use request_key() to add
345 * keys to the original requestor's destination keyring.
346 */
347 if (dest_keyring && do_perm_check) {
348 ret = key_permission(make_key_ref(dest_keyring, 1),
349 KEY_NEED_WRITE);
350 if (ret) {
351 key_put(dest_keyring);
352 return ret;
353 }
354 }
355 }
356
357 *_dest_keyring = dest_keyring;
358 kleave(" [dk %d]", key_serial(dest_keyring));
359 return 0;
360 }
361
362 /*
363 * Allocate a new key in under-construction state and attempt to link it in to
364 * the requested keyring.
365 *
366 * May return a key that's already under construction instead if there was a
367 * race between two thread calling request_key().
368 */
369 static int construct_alloc_key(struct keyring_search_context *ctx,
370 struct key *dest_keyring,
371 unsigned long flags,
372 struct key_user *user,
373 struct key **_key)
374 {
375 struct assoc_array_edit *edit = NULL;
376 struct key *key;
377 key_perm_t perm;
378 key_ref_t key_ref;
379 int ret;
380
381 kenter("%s,%s,,,",
382 ctx->index_key.type->name, ctx->index_key.description);
383
384 *_key = NULL;
385 mutex_lock(&user->cons_lock);
386
387 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
388 perm |= KEY_USR_VIEW;
389 if (ctx->index_key.type->read)
390 perm |= KEY_POS_READ;
391 if (ctx->index_key.type == &key_type_keyring ||
392 ctx->index_key.type->update)
393 perm |= KEY_POS_WRITE;
394
395 key = key_alloc(ctx->index_key.type, ctx->index_key.description,
396 ctx->cred->fsuid, ctx->cred->fsgid, ctx->cred,
397 perm, flags, NULL);
398 if (IS_ERR(key))
399 goto alloc_failed;
400
401 set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
402
403 if (dest_keyring) {
404 ret = __key_link_lock(dest_keyring, &key->index_key);
405 if (ret < 0)
406 goto link_lock_failed;
407 }
408
409 /*
410 * Attach the key to the destination keyring under lock, but we do need
411 * to do another check just in case someone beat us to it whilst we
412 * waited for locks.
413 *
414 * The caller might specify a comparison function which looks for keys
415 * that do not exactly match but are still equivalent from the caller's
416 * perspective. The __key_link_begin() operation must be done only after
417 * an actual key is determined.
418 */
419 mutex_lock(&key_construction_mutex);
420
421 rcu_read_lock();
422 key_ref = search_process_keyrings_rcu(ctx);
423 rcu_read_unlock();
424 if (!IS_ERR(key_ref))
425 goto key_already_present;
426
427 if (dest_keyring) {
428 ret = __key_link_begin(dest_keyring, &key->index_key, &edit);
429 if (ret < 0)
430 goto link_alloc_failed;
431 __key_link(dest_keyring, key, &edit);
432 }
433
434 mutex_unlock(&key_construction_mutex);
435 if (dest_keyring)
436 __key_link_end(dest_keyring, &key->index_key, edit);
437 mutex_unlock(&user->cons_lock);
438 *_key = key;
439 kleave(" = 0 [%d]", key_serial(key));
440 return 0;
441
442 /* the key is now present - we tell the caller that we found it by
443 * returning -EINPROGRESS */
444 key_already_present:
445 key_put(key);
446 mutex_unlock(&key_construction_mutex);
447 key = key_ref_to_ptr(key_ref);
448 if (dest_keyring) {
449 ret = __key_link_begin(dest_keyring, &key->index_key, &edit);
450 if (ret < 0)
451 goto link_alloc_failed_unlocked;
452 ret = __key_link_check_live_key(dest_keyring, key);
453 if (ret == 0)
454 __key_link(dest_keyring, key, &edit);
455 __key_link_end(dest_keyring, &key->index_key, edit);
456 if (ret < 0)
457 goto link_check_failed;
458 }
459 mutex_unlock(&user->cons_lock);
460 *_key = key;
461 kleave(" = -EINPROGRESS [%d]", key_serial(key));
462 return -EINPROGRESS;
463
464 link_check_failed:
465 mutex_unlock(&user->cons_lock);
466 key_put(key);
467 kleave(" = %d [linkcheck]", ret);
468 return ret;
469
470 link_alloc_failed:
471 mutex_unlock(&key_construction_mutex);
472 link_alloc_failed_unlocked:
473 __key_link_end(dest_keyring, &key->index_key, edit);
474 link_lock_failed:
475 mutex_unlock(&user->cons_lock);
476 key_put(key);
477 kleave(" = %d [prelink]", ret);
478 return ret;
479
480 alloc_failed:
481 mutex_unlock(&user->cons_lock);
482 kleave(" = %ld", PTR_ERR(key));
483 return PTR_ERR(key);
484 }
485
486 /*
487 * Commence key construction.
488 */
489 static struct key *construct_key_and_link(struct keyring_search_context *ctx,
490 const char *callout_info,
491 size_t callout_len,
492 void *aux,
493 struct key *dest_keyring,
494 unsigned long flags)
495 {
496 struct key_user *user;
497 struct key *key;
498 int ret;
499
500 kenter("");
501
502 if (ctx->index_key.type == &key_type_keyring)
503 return ERR_PTR(-EPERM);
504
505 ret = construct_get_dest_keyring(&dest_keyring);
506 if (ret)
507 goto error;
508
509 user = key_user_lookup(current_fsuid());
510 if (!user) {
511 ret = -ENOMEM;
512 goto error_put_dest_keyring;
513 }
514
515 ret = construct_alloc_key(ctx, dest_keyring, flags, user, &key);
516 key_user_put(user);
517
518 if (ret == 0) {
519 ret = construct_key(key, callout_info, callout_len, aux,
520 dest_keyring);
521 if (ret < 0) {
522 kdebug("cons failed");
523 goto construction_failed;
524 }
525 } else if (ret == -EINPROGRESS) {
526 ret = 0;
527 } else {
528 goto error_put_dest_keyring;
529 }
530
531 key_put(dest_keyring);
532 kleave(" = key %d", key_serial(key));
533 return key;
534
535 construction_failed:
536 key_negate_and_link(key, key_negative_timeout, NULL, NULL);
537 key_put(key);
538 error_put_dest_keyring:
539 key_put(dest_keyring);
540 error:
541 kleave(" = %d", ret);
542 return ERR_PTR(ret);
543 }
544
545 /**
546 * request_key_and_link - Request a key and cache it in a keyring.
547 * @type: The type of key we want.
548 * @description: The searchable description of the key.
549 * @domain_tag: The domain in which the key operates.
550 * @callout_info: The data to pass to the instantiation upcall (or NULL).
551 * @callout_len: The length of callout_info.
552 * @aux: Auxiliary data for the upcall.
553 * @dest_keyring: Where to cache the key.
554 * @flags: Flags to key_alloc().
555 *
556 * A key matching the specified criteria (type, description, domain_tag) is
557 * searched for in the process's keyrings and returned with its usage count
558 * incremented if found. Otherwise, if callout_info is not NULL, a key will be
559 * allocated and some service (probably in userspace) will be asked to
560 * instantiate it.
561 *
562 * If successfully found or created, the key will be linked to the destination
563 * keyring if one is provided.
564 *
565 * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
566 * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
567 * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
568 * if insufficient key quota was available to create a new key; or -ENOMEM if
569 * insufficient memory was available.
570 *
571 * If the returned key was created, then it may still be under construction,
572 * and wait_for_key_construction() should be used to wait for that to complete.
573 */
574 struct key *request_key_and_link(struct key_type *type,
575 const char *description,
576 struct key_tag *domain_tag,
577 const void *callout_info,
578 size_t callout_len,
579 void *aux,
580 struct key *dest_keyring,
581 unsigned long flags)
582 {
583 struct keyring_search_context ctx = {
584 .index_key.type = type,
585 .index_key.domain_tag = domain_tag,
586 .index_key.description = description,
587 .index_key.desc_len = strlen(description),
588 .cred = current_cred(),
589 .match_data.cmp = key_default_cmp,
590 .match_data.raw_data = description,
591 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
592 .flags = (KEYRING_SEARCH_DO_STATE_CHECK |
593 KEYRING_SEARCH_SKIP_EXPIRED |
594 KEYRING_SEARCH_RECURSE),
595 };
596 struct key *key;
597 key_ref_t key_ref;
598 int ret;
599
600 kenter("%s,%s,%p,%zu,%p,%p,%lx",
601 ctx.index_key.type->name, ctx.index_key.description,
602 callout_info, callout_len, aux, dest_keyring, flags);
603
604 if (type->match_preparse) {
605 ret = type->match_preparse(&ctx.match_data);
606 if (ret < 0) {
607 key = ERR_PTR(ret);
608 goto error;
609 }
610 }
611
612 key = check_cached_key(&ctx);
613 if (key)
614 goto error_free;
615
616 /* search all the process keyrings for a key */
617 rcu_read_lock();
618 key_ref = search_process_keyrings_rcu(&ctx);
619 rcu_read_unlock();
620
621 if (!IS_ERR(key_ref)) {
622 if (dest_keyring) {
623 ret = key_task_permission(key_ref, current_cred(),
624 KEY_NEED_LINK);
625 if (ret < 0) {
626 key_ref_put(key_ref);
627 key = ERR_PTR(ret);
628 goto error_free;
629 }
630 }
631
632 key = key_ref_to_ptr(key_ref);
633 if (dest_keyring) {
634 ret = key_link(dest_keyring, key);
635 if (ret < 0) {
636 key_put(key);
637 key = ERR_PTR(ret);
638 goto error_free;
639 }
640 }
641
642 /* Only cache the key on immediate success */
643 cache_requested_key(key);
644 } else if (PTR_ERR(key_ref) != -EAGAIN) {
645 key = ERR_CAST(key_ref);
646 } else {
647 /* the search failed, but the keyrings were searchable, so we
648 * should consult userspace if we can */
649 key = ERR_PTR(-ENOKEY);
650 if (!callout_info)
651 goto error_free;
652
653 key = construct_key_and_link(&ctx, callout_info, callout_len,
654 aux, dest_keyring, flags);
655 }
656
657 error_free:
658 if (type->match_free)
659 type->match_free(&ctx.match_data);
660 error:
661 kleave(" = %p", key);
662 return key;
663 }
664
665 /**
666 * wait_for_key_construction - Wait for construction of a key to complete
667 * @key: The key being waited for.
668 * @intr: Whether to wait interruptibly.
669 *
670 * Wait for a key to finish being constructed.
671 *
672 * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
673 * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
674 * revoked or expired.
675 */
676 int wait_for_key_construction(struct key *key, bool intr)
677 {
678 int ret;
679
680 ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
681 intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
682 if (ret)
683 return -ERESTARTSYS;
684 ret = key_read_state(key);
685 if (ret < 0)
686 return ret;
687 return key_validate(key);
688 }
689 EXPORT_SYMBOL(wait_for_key_construction);
690
691 /**
692 * request_key_tag - Request a key and wait for construction
693 * @type: Type of key.
694 * @description: The searchable description of the key.
695 * @domain_tag: The domain in which the key operates.
696 * @callout_info: The data to pass to the instantiation upcall (or NULL).
697 *
698 * As for request_key_and_link() except that it does not add the returned key
699 * to a keyring if found, new keys are always allocated in the user's quota,
700 * the callout_info must be a NUL-terminated string and no auxiliary data can
701 * be passed.
702 *
703 * Furthermore, it then works as wait_for_key_construction() to wait for the
704 * completion of keys undergoing construction with a non-interruptible wait.
705 */
706 struct key *request_key_tag(struct key_type *type,
707 const char *description,
708 struct key_tag *domain_tag,
709 const char *callout_info)
710 {
711 struct key *key;
712 size_t callout_len = 0;
713 int ret;
714
715 if (callout_info)
716 callout_len = strlen(callout_info);
717 key = request_key_and_link(type, description, domain_tag,
718 callout_info, callout_len,
719 NULL, NULL, KEY_ALLOC_IN_QUOTA);
720 if (!IS_ERR(key)) {
721 ret = wait_for_key_construction(key, false);
722 if (ret < 0) {
723 key_put(key);
724 return ERR_PTR(ret);
725 }
726 }
727 return key;
728 }
729 EXPORT_SYMBOL(request_key_tag);
730
731 /**
732 * request_key_with_auxdata - Request a key with auxiliary data for the upcaller
733 * @type: The type of key we want.
734 * @description: The searchable description of the key.
735 * @domain_tag: The domain in which the key operates.
736 * @callout_info: The data to pass to the instantiation upcall (or NULL).
737 * @callout_len: The length of callout_info.
738 * @aux: Auxiliary data for the upcall.
739 *
740 * As for request_key_and_link() except that it does not add the returned key
741 * to a keyring if found and new keys are always allocated in the user's quota.
742 *
743 * Furthermore, it then works as wait_for_key_construction() to wait for the
744 * completion of keys undergoing construction with a non-interruptible wait.
745 */
746 struct key *request_key_with_auxdata(struct key_type *type,
747 const char *description,
748 struct key_tag *domain_tag,
749 const void *callout_info,
750 size_t callout_len,
751 void *aux)
752 {
753 struct key *key;
754 int ret;
755
756 key = request_key_and_link(type, description, domain_tag,
757 callout_info, callout_len,
758 aux, NULL, KEY_ALLOC_IN_QUOTA);
759 if (!IS_ERR(key)) {
760 ret = wait_for_key_construction(key, false);
761 if (ret < 0) {
762 key_put(key);
763 return ERR_PTR(ret);
764 }
765 }
766 return key;
767 }
768 EXPORT_SYMBOL(request_key_with_auxdata);
769
770 /**
771 * request_key_rcu - Request key from RCU-read-locked context
772 * @type: The type of key we want.
773 * @description: The name of the key we want.
774 * @domain_tag: The domain in which the key operates.
775 *
776 * Request a key from a context that we may not sleep in (such as RCU-mode
777 * pathwalk). Keys under construction are ignored.
778 *
779 * Return a pointer to the found key if successful, -ENOKEY if we couldn't find
780 * a key or some other error if the key found was unsuitable or inaccessible.
781 */
782 struct key *request_key_rcu(struct key_type *type,
783 const char *description,
784 struct key_tag *domain_tag)
785 {
786 struct keyring_search_context ctx = {
787 .index_key.type = type,
788 .index_key.domain_tag = domain_tag,
789 .index_key.description = description,
790 .index_key.desc_len = strlen(description),
791 .cred = current_cred(),
792 .match_data.cmp = key_default_cmp,
793 .match_data.raw_data = description,
794 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
795 .flags = (KEYRING_SEARCH_DO_STATE_CHECK |
796 KEYRING_SEARCH_SKIP_EXPIRED),
797 };
798 struct key *key;
799 key_ref_t key_ref;
800
801 kenter("%s,%s", type->name, description);
802
803 key = check_cached_key(&ctx);
804 if (key)
805 return key;
806
807 /* search all the process keyrings for a key */
808 key_ref = search_process_keyrings_rcu(&ctx);
809 if (IS_ERR(key_ref)) {
810 key = ERR_CAST(key_ref);
811 if (PTR_ERR(key_ref) == -EAGAIN)
812 key = ERR_PTR(-ENOKEY);
813 } else {
814 key = key_ref_to_ptr(key_ref);
815 cache_requested_key(key);
816 }
817
818 kleave(" = %p", key);
819 return key;
820 }
821 EXPORT_SYMBOL(request_key_rcu);
822
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