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