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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 * 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.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);