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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.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, int wait)
95{
96 struct subprocess_info *info;
97
98 info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL,
99 umh_keys_init, umh_keys_cleanup,
100 session_keyring);
101 if (!info)
102 return -ENOMEM;
103
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_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
137 KEY_ALLOC_QUOTA_OVERRUN, NULL);
138 put_cred(cred);
139 if (IS_ERR(keyring)) {
140 ret = PTR_ERR(keyring);
141 goto error_alloc;
142 }
143
144 /* attach the auth key to the session keyring */
145 ret = key_link(keyring, authkey);
146 if (ret < 0)
147 goto error_link;
148
149 /* record the UID and GID */
150 sprintf(uid_str, "%d", from_kuid(&init_user_ns, cred->fsuid));
151 sprintf(gid_str, "%d", from_kgid(&init_user_ns, cred->fsgid));
152
153 /* we say which key is under construction */
154 sprintf(key_str, "%d", key->serial);
155
156 /* we specify the process's default keyrings */
157 sprintf(keyring_str[0], "%d",
158 cred->thread_keyring ? cred->thread_keyring->serial : 0);
159
160 prkey = 0;
161 if (cred->process_keyring)
162 prkey = cred->process_keyring->serial;
163 sprintf(keyring_str[1], "%d", prkey);
164
165 rcu_read_lock();
166 session = rcu_dereference(cred->session_keyring);
167 if (!session)
168 session = cred->user->session_keyring;
169 sskey = session->serial;
170 rcu_read_unlock();
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++] = "/sbin/request-key";
183 argv[i++] = (char *) 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(argv[0], argv, envp, keyring,
194 UMH_WAIT_PROC);
195 kdebug("usermode -> 0x%x", ret);
196 if (ret >= 0) {
197 /* ret is the exit/wait code */
198 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
199 key_validate(key) < 0)
200 ret = -ENOKEY;
201 else
202 /* ignore any errors from userspace if the key was
203 * instantiated */
204 ret = 0;
205 }
206
207error_link:
208 key_put(keyring);
209
210error_alloc:
211 complete_request_key(cons, ret);
212 kleave(" = %d", ret);
213 return ret;
214}
215
216/*
217 * Call out to userspace for key construction.
218 *
219 * Program failure is ignored in favour of key status.
220 */
221static int construct_key(struct key *key, const void *callout_info,
222 size_t callout_len, void *aux,
223 struct key *dest_keyring)
224{
225 struct key_construction *cons;
226 request_key_actor_t actor;
227 struct key *authkey;
228 int ret;
229
230 kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
231
232 cons = kmalloc(sizeof(*cons), GFP_KERNEL);
233 if (!cons)
234 return -ENOMEM;
235
236 /* allocate an authorisation key */
237 authkey = request_key_auth_new(key, callout_info, callout_len,
238 dest_keyring);
239 if (IS_ERR(authkey)) {
240 kfree(cons);
241 ret = PTR_ERR(authkey);
242 authkey = NULL;
243 } else {
244 cons->authkey = key_get(authkey);
245 cons->key = key_get(key);
246
247 /* make the call */
248 actor = call_sbin_request_key;
249 if (key->type->request_key)
250 actor = key->type->request_key;
251
252 ret = actor(cons, "create", aux);
253
254 /* check that the actor called complete_request_key() prior to
255 * returning an error */
256 WARN_ON(ret < 0 &&
257 !test_bit(KEY_FLAG_REVOKED, &authkey->flags));
258 key_put(authkey);
259 }
260
261 kleave(" = %d", ret);
262 return ret;
263}
264
265/*
266 * Get the appropriate destination keyring for the request.
267 *
268 * The keyring selected is returned with an extra reference upon it which the
269 * caller must release.
270 */
271static void construct_get_dest_keyring(struct key **_dest_keyring)
272{
273 struct request_key_auth *rka;
274 const struct cred *cred = current_cred();
275 struct key *dest_keyring = *_dest_keyring, *authkey;
276
277 kenter("%p", dest_keyring);
278
279 /* find the appropriate keyring */
280 if (dest_keyring) {
281 /* the caller supplied one */
282 key_get(dest_keyring);
283 } else {
284 /* use a default keyring; falling through the cases until we
285 * find one that we actually have */
286 switch (cred->jit_keyring) {
287 case KEY_REQKEY_DEFL_DEFAULT:
288 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
289 if (cred->request_key_auth) {
290 authkey = cred->request_key_auth;
291 down_read(&authkey->sem);
292 rka = authkey->payload.data;
293 if (!test_bit(KEY_FLAG_REVOKED,
294 &authkey->flags))
295 dest_keyring =
296 key_get(rka->dest_keyring);
297 up_read(&authkey->sem);
298 if (dest_keyring)
299 break;
300 }
301
302 case KEY_REQKEY_DEFL_THREAD_KEYRING:
303 dest_keyring = key_get(cred->thread_keyring);
304 if (dest_keyring)
305 break;
306
307 case KEY_REQKEY_DEFL_PROCESS_KEYRING:
308 dest_keyring = key_get(cred->process_keyring);
309 if (dest_keyring)
310 break;
311
312 case KEY_REQKEY_DEFL_SESSION_KEYRING:
313 rcu_read_lock();
314 dest_keyring = key_get(
315 rcu_dereference(cred->session_keyring));
316 rcu_read_unlock();
317
318 if (dest_keyring)
319 break;
320
321 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
322 dest_keyring =
323 key_get(cred->user->session_keyring);
324 break;
325
326 case KEY_REQKEY_DEFL_USER_KEYRING:
327 dest_keyring = key_get(cred->user->uid_keyring);
328 break;
329
330 case KEY_REQKEY_DEFL_GROUP_KEYRING:
331 default:
332 BUG();
333 }
334 }
335
336 *_dest_keyring = dest_keyring;
337 kleave(" [dk %d]", key_serial(dest_keyring));
338 return;
339}
340
341/*
342 * Allocate a new key in under-construction state and attempt to link it in to
343 * the requested keyring.
344 *
345 * May return a key that's already under construction instead if there was a
346 * race between two thread calling request_key().
347 */
348static int construct_alloc_key(struct keyring_search_context *ctx,
349 struct key *dest_keyring,
350 unsigned long flags,
351 struct key_user *user,
352 struct key **_key)
353{
354 struct assoc_array_edit *edit;
355 struct key *key;
356 key_perm_t perm;
357 key_ref_t key_ref;
358 int ret;
359
360 kenter("%s,%s,,,",
361 ctx->index_key.type->name, ctx->index_key.description);
362
363 *_key = NULL;
364 mutex_lock(&user->cons_lock);
365
366 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
367 perm |= KEY_USR_VIEW;
368 if (ctx->index_key.type->read)
369 perm |= KEY_POS_READ;
370 if (ctx->index_key.type == &key_type_keyring ||
371 ctx->index_key.type->update)
372 perm |= KEY_POS_WRITE;
373
374 key = key_alloc(ctx->index_key.type, ctx->index_key.description,
375 ctx->cred->fsuid, ctx->cred->fsgid, ctx->cred,
376 perm, flags);
377 if (IS_ERR(key))
378 goto alloc_failed;
379
380 set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
381
382 if (dest_keyring) {
383 ret = __key_link_begin(dest_keyring, &ctx->index_key, &edit);
384 if (ret < 0)
385 goto link_prealloc_failed;
386 }
387
388 /* attach the key to the destination keyring under lock, but we do need
389 * to do another check just in case someone beat us to it whilst we
390 * waited for locks */
391 mutex_lock(&key_construction_mutex);
392
393 key_ref = search_process_keyrings(ctx);
394 if (!IS_ERR(key_ref))
395 goto key_already_present;
396
397 if (dest_keyring)
398 __key_link(key, &edit);
399
400 mutex_unlock(&key_construction_mutex);
401 if (dest_keyring)
402 __key_link_end(dest_keyring, &ctx->index_key, edit);
403 mutex_unlock(&user->cons_lock);
404 *_key = key;
405 kleave(" = 0 [%d]", key_serial(key));
406 return 0;
407
408 /* the key is now present - we tell the caller that we found it by
409 * returning -EINPROGRESS */
410key_already_present:
411 key_put(key);
412 mutex_unlock(&key_construction_mutex);
413 key = key_ref_to_ptr(key_ref);
414 if (dest_keyring) {
415 ret = __key_link_check_live_key(dest_keyring, key);
416 if (ret == 0)
417 __key_link(key, &edit);
418 __key_link_end(dest_keyring, &ctx->index_key, edit);
419 if (ret < 0)
420 goto link_check_failed;
421 }
422 mutex_unlock(&user->cons_lock);
423 *_key = key;
424 kleave(" = -EINPROGRESS [%d]", key_serial(key));
425 return -EINPROGRESS;
426
427link_check_failed:
428 mutex_unlock(&user->cons_lock);
429 key_put(key);
430 kleave(" = %d [linkcheck]", ret);
431 return ret;
432
433link_prealloc_failed:
434 mutex_unlock(&user->cons_lock);
435 kleave(" = %d [prelink]", ret);
436 return ret;
437
438alloc_failed:
439 mutex_unlock(&user->cons_lock);
440 kleave(" = %ld", PTR_ERR(key));
441 return PTR_ERR(key);
442}
443
444/*
445 * Commence key construction.
446 */
447static struct key *construct_key_and_link(struct keyring_search_context *ctx,
448 const char *callout_info,
449 size_t callout_len,
450 void *aux,
451 struct key *dest_keyring,
452 unsigned long flags)
453{
454 struct key_user *user;
455 struct key *key;
456 int ret;
457
458 kenter("");
459
460 user = key_user_lookup(current_fsuid());
461 if (!user)
462 return ERR_PTR(-ENOMEM);
463
464 construct_get_dest_keyring(&dest_keyring);
465
466 ret = construct_alloc_key(ctx, dest_keyring, flags, user, &key);
467 key_user_put(user);
468
469 if (ret == 0) {
470 ret = construct_key(key, callout_info, callout_len, aux,
471 dest_keyring);
472 if (ret < 0) {
473 kdebug("cons failed");
474 goto construction_failed;
475 }
476 } else if (ret == -EINPROGRESS) {
477 ret = 0;
478 } else {
479 goto couldnt_alloc_key;
480 }
481
482 key_put(dest_keyring);
483 kleave(" = key %d", key_serial(key));
484 return key;
485
486construction_failed:
487 key_negate_and_link(key, key_negative_timeout, NULL, NULL);
488 key_put(key);
489couldnt_alloc_key:
490 key_put(dest_keyring);
491 kleave(" = %d", ret);
492 return ERR_PTR(ret);
493}
494
495/**
496 * request_key_and_link - Request a key and cache it in a keyring.
497 * @type: The type of key we want.
498 * @description: The searchable description of the key.
499 * @callout_info: The data to pass to the instantiation upcall (or NULL).
500 * @callout_len: The length of callout_info.
501 * @aux: Auxiliary data for the upcall.
502 * @dest_keyring: Where to cache the key.
503 * @flags: Flags to key_alloc().
504 *
505 * A key matching the specified criteria is searched for in the process's
506 * keyrings and returned with its usage count incremented if found. Otherwise,
507 * if callout_info is not NULL, a key will be allocated and some service
508 * (probably in userspace) will be asked to instantiate it.
509 *
510 * If successfully found or created, the key will be linked to the destination
511 * keyring if one is provided.
512 *
513 * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
514 * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
515 * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
516 * if insufficient key quota was available to create a new key; or -ENOMEM if
517 * insufficient memory was available.
518 *
519 * If the returned key was created, then it may still be under construction,
520 * and wait_for_key_construction() should be used to wait for that to complete.
521 */
522struct key *request_key_and_link(struct key_type *type,
523 const char *description,
524 const void *callout_info,
525 size_t callout_len,
526 void *aux,
527 struct key *dest_keyring,
528 unsigned long flags)
529{
530 struct keyring_search_context ctx = {
531 .index_key.type = type,
532 .index_key.description = description,
533 .cred = current_cred(),
534 .match = type->match,
535 .match_data = description,
536 .flags = KEYRING_SEARCH_LOOKUP_DIRECT,
537 };
538 struct key *key;
539 key_ref_t key_ref;
540 int ret;
541
542 kenter("%s,%s,%p,%zu,%p,%p,%lx",
543 ctx.index_key.type->name, ctx.index_key.description,
544 callout_info, callout_len, aux, dest_keyring, flags);
545
546 /* search all the process keyrings for a key */
547 key_ref = search_process_keyrings(&ctx);
548
549 if (!IS_ERR(key_ref)) {
550 key = key_ref_to_ptr(key_ref);
551 if (dest_keyring) {
552 construct_get_dest_keyring(&dest_keyring);
553 ret = key_link(dest_keyring, key);
554 key_put(dest_keyring);
555 if (ret < 0) {
556 key_put(key);
557 key = ERR_PTR(ret);
558 goto error;
559 }
560 }
561 } else if (PTR_ERR(key_ref) != -EAGAIN) {
562 key = ERR_CAST(key_ref);
563 } else {
564 /* the search failed, but the keyrings were searchable, so we
565 * should consult userspace if we can */
566 key = ERR_PTR(-ENOKEY);
567 if (!callout_info)
568 goto error;
569
570 key = construct_key_and_link(&ctx, callout_info, callout_len,
571 aux, dest_keyring, flags);
572 }
573
574error:
575 kleave(" = %p", key);
576 return key;
577}
578
579/**
580 * wait_for_key_construction - Wait for construction of a key to complete
581 * @key: The key being waited for.
582 * @intr: Whether to wait interruptibly.
583 *
584 * Wait for a key to finish being constructed.
585 *
586 * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
587 * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
588 * revoked or expired.
589 */
590int wait_for_key_construction(struct key *key, bool intr)
591{
592 int ret;
593
594 ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
595 intr ? key_wait_bit_intr : key_wait_bit,
596 intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
597 if (ret < 0)
598 return ret;
599 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) {
600 smp_rmb();
601 return key->type_data.reject_error;
602 }
603 return key_validate(key);
604}
605EXPORT_SYMBOL(wait_for_key_construction);
606
607/**
608 * request_key - Request a key and wait for construction
609 * @type: Type of key.
610 * @description: The searchable description of the key.
611 * @callout_info: The data to pass to the instantiation upcall (or NULL).
612 *
613 * As for request_key_and_link() except that it does not add the returned key
614 * to a keyring if found, new keys are always allocated in the user's quota,
615 * the callout_info must be a NUL-terminated string and no auxiliary data can
616 * be passed.
617 *
618 * Furthermore, it then works as wait_for_key_construction() to wait for the
619 * completion of keys undergoing construction with a non-interruptible wait.
620 */
621struct key *request_key(struct key_type *type,
622 const char *description,
623 const char *callout_info)
624{
625 struct key *key;
626 size_t callout_len = 0;
627 int ret;
628
629 if (callout_info)
630 callout_len = strlen(callout_info);
631 key = request_key_and_link(type, description, callout_info, callout_len,
632 NULL, NULL, KEY_ALLOC_IN_QUOTA);
633 if (!IS_ERR(key)) {
634 ret = wait_for_key_construction(key, false);
635 if (ret < 0) {
636 key_put(key);
637 return ERR_PTR(ret);
638 }
639 }
640 return key;
641}
642EXPORT_SYMBOL(request_key);
643
644/**
645 * request_key_with_auxdata - Request a key with auxiliary data for the upcaller
646 * @type: The type of key we want.
647 * @description: The searchable description of the key.
648 * @callout_info: The data to pass to the instantiation upcall (or NULL).
649 * @callout_len: The length of callout_info.
650 * @aux: Auxiliary data for the upcall.
651 *
652 * As for request_key_and_link() except that it does not add the returned key
653 * to a keyring if found and new keys are always allocated in the user's quota.
654 *
655 * Furthermore, it then works as wait_for_key_construction() to wait for the
656 * completion of keys undergoing construction with a non-interruptible wait.
657 */
658struct key *request_key_with_auxdata(struct key_type *type,
659 const char *description,
660 const void *callout_info,
661 size_t callout_len,
662 void *aux)
663{
664 struct key *key;
665 int ret;
666
667 key = request_key_and_link(type, description, callout_info, callout_len,
668 aux, NULL, KEY_ALLOC_IN_QUOTA);
669 if (!IS_ERR(key)) {
670 ret = wait_for_key_construction(key, false);
671 if (ret < 0) {
672 key_put(key);
673 return ERR_PTR(ret);
674 }
675 }
676 return key;
677}
678EXPORT_SYMBOL(request_key_with_auxdata);
679
680/*
681 * request_key_async - Request a key (allow async construction)
682 * @type: Type of key.
683 * @description: The searchable description of the key.
684 * @callout_info: The data to pass to the instantiation upcall (or NULL).
685 * @callout_len: The length of callout_info.
686 *
687 * As for request_key_and_link() except that it does not add the returned key
688 * to a keyring if found, new keys are always allocated in the user's quota and
689 * no auxiliary data can be passed.
690 *
691 * The caller should call wait_for_key_construction() to wait for the
692 * completion of the returned key if it is still undergoing construction.
693 */
694struct key *request_key_async(struct key_type *type,
695 const char *description,
696 const void *callout_info,
697 size_t callout_len)
698{
699 return request_key_and_link(type, description, callout_info,
700 callout_len, NULL, NULL,
701 KEY_ALLOC_IN_QUOTA);
702}
703EXPORT_SYMBOL(request_key_async);
704
705/*
706 * request a key with auxiliary data for the upcaller (allow async construction)
707 * @type: Type of key.
708 * @description: The searchable description of the key.
709 * @callout_info: The data to pass to the instantiation upcall (or NULL).
710 * @callout_len: The length of callout_info.
711 * @aux: Auxiliary data for the upcall.
712 *
713 * As for request_key_and_link() except that it does not add the returned key
714 * to a keyring if found and new keys are always allocated in the user's quota.
715 *
716 * The caller should call wait_for_key_construction() to wait for the
717 * completion of the returned key if it is still undergoing construction.
718 */
719struct key *request_key_async_with_auxdata(struct key_type *type,
720 const char *description,
721 const void *callout_info,
722 size_t callout_len,
723 void *aux)
724{
725 return request_key_and_link(type, description, callout_info,
726 callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
727}
728EXPORT_SYMBOL(request_key_async_with_auxdata);