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