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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* process_keys.c: management of a process's keyrings
2 *
3 * Copyright (C) 2004 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
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/sched.h>
15#include <linux/slab.h>
16#include <linux/keyctl.h>
17#include <linux/fs.h>
18#include <linux/err.h>
19#include <asm/uaccess.h>
20#include "internal.h"
21
22/* session keyring create vs join semaphore */
23static DECLARE_MUTEX(key_session_sem);
24
25/* the root user's tracking struct */
26struct key_user root_key_user = {
27 .usage = ATOMIC_INIT(3),
28 .consq = LIST_HEAD_INIT(root_key_user.consq),
29 .lock = SPIN_LOCK_UNLOCKED,
30 .nkeys = ATOMIC_INIT(2),
31 .nikeys = ATOMIC_INIT(2),
32 .uid = 0,
33};
34
35/* the root user's UID keyring */
36struct key root_user_keyring = {
37 .usage = ATOMIC_INIT(1),
38 .serial = 2,
39 .type = &key_type_keyring,
40 .user = &root_key_user,
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 .sem = __RWSEM_INITIALIZER(root_user_keyring.sem),
42 .perm = KEY_USR_ALL,
David Howells76d8aea2005-06-23 22:00:49 -070043 .flags = 1 << KEY_FLAG_INSTANTIATED,
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 .description = "_uid.0",
45#ifdef KEY_DEBUGGING
46 .magic = KEY_DEBUG_MAGIC,
47#endif
48};
49
50/* the root user's default session keyring */
51struct key root_session_keyring = {
52 .usage = ATOMIC_INIT(1),
53 .serial = 1,
54 .type = &key_type_keyring,
55 .user = &root_key_user,
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 .sem = __RWSEM_INITIALIZER(root_session_keyring.sem),
57 .perm = KEY_USR_ALL,
David Howells76d8aea2005-06-23 22:00:49 -070058 .flags = 1 << KEY_FLAG_INSTANTIATED,
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 .description = "_uid_ses.0",
60#ifdef KEY_DEBUGGING
61 .magic = KEY_DEBUG_MAGIC,
62#endif
63};
64
65/*****************************************************************************/
66/*
67 * allocate the keyrings to be associated with a UID
68 */
69int alloc_uid_keyring(struct user_struct *user)
70{
71 struct key *uid_keyring, *session_keyring;
72 char buf[20];
73 int ret;
74
75 /* concoct a default session keyring */
76 sprintf(buf, "_uid_ses.%u", user->uid);
77
78 session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, 0, NULL);
79 if (IS_ERR(session_keyring)) {
80 ret = PTR_ERR(session_keyring);
81 goto error;
82 }
83
84 /* and a UID specific keyring, pointed to by the default session
85 * keyring */
86 sprintf(buf, "_uid.%u", user->uid);
87
88 uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, 0,
89 session_keyring);
90 if (IS_ERR(uid_keyring)) {
91 key_put(session_keyring);
92 ret = PTR_ERR(uid_keyring);
93 goto error;
94 }
95
96 /* install the keyrings */
97 user->uid_keyring = uid_keyring;
98 user->session_keyring = session_keyring;
99 ret = 0;
100
101 error:
102 return ret;
103
104} /* end alloc_uid_keyring() */
105
106/*****************************************************************************/
107/*
108 * deal with the UID changing
109 */
110void switch_uid_keyring(struct user_struct *new_user)
111{
112#if 0 /* do nothing for now */
113 struct key *old;
114
115 /* switch to the new user's session keyring if we were running under
116 * root's default session keyring */
117 if (new_user->uid != 0 &&
118 current->session_keyring == &root_session_keyring
119 ) {
120 atomic_inc(&new_user->session_keyring->usage);
121
122 task_lock(current);
123 old = current->session_keyring;
124 current->session_keyring = new_user->session_keyring;
125 task_unlock(current);
126
127 key_put(old);
128 }
129#endif
130
131} /* end switch_uid_keyring() */
132
133/*****************************************************************************/
134/*
135 * install a fresh thread keyring, discarding the old one
136 */
137int install_thread_keyring(struct task_struct *tsk)
138{
139 struct key *keyring, *old;
140 char buf[20];
141 int ret;
142
143 sprintf(buf, "_tid.%u", tsk->pid);
144
145 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
146 if (IS_ERR(keyring)) {
147 ret = PTR_ERR(keyring);
148 goto error;
149 }
150
151 task_lock(tsk);
152 old = tsk->thread_keyring;
153 tsk->thread_keyring = keyring;
154 task_unlock(tsk);
155
156 ret = 0;
157
158 key_put(old);
159 error:
160 return ret;
161
162} /* end install_thread_keyring() */
163
164/*****************************************************************************/
165/*
166 * make sure a process keyring is installed
167 */
168static int install_process_keyring(struct task_struct *tsk)
169{
170 unsigned long flags;
171 struct key *keyring;
172 char buf[20];
173 int ret;
174
175 if (!tsk->signal->process_keyring) {
176 sprintf(buf, "_pid.%u", tsk->tgid);
177
178 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
179 if (IS_ERR(keyring)) {
180 ret = PTR_ERR(keyring);
181 goto error;
182 }
183
184 /* attach or swap keyrings */
185 spin_lock_irqsave(&tsk->sighand->siglock, flags);
186 if (!tsk->signal->process_keyring) {
187 tsk->signal->process_keyring = keyring;
188 keyring = NULL;
189 }
190 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
191
192 key_put(keyring);
193 }
194
195 ret = 0;
196 error:
197 return ret;
198
199} /* end install_process_keyring() */
200
201/*****************************************************************************/
202/*
203 * install a session keyring, discarding the old one
204 * - if a keyring is not supplied, an empty one is invented
205 */
206static int install_session_keyring(struct task_struct *tsk,
207 struct key *keyring)
208{
209 unsigned long flags;
210 struct key *old;
211 char buf[20];
212 int ret;
213
214 /* create an empty session keyring */
215 if (!keyring) {
216 sprintf(buf, "_ses.%u", tsk->tgid);
217
218 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
219 if (IS_ERR(keyring)) {
220 ret = PTR_ERR(keyring);
221 goto error;
222 }
223 }
224 else {
225 atomic_inc(&keyring->usage);
226 }
227
228 /* install the keyring */
229 spin_lock_irqsave(&tsk->sighand->siglock, flags);
230 old = tsk->signal->session_keyring;
231 tsk->signal->session_keyring = keyring;
232 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
233
234 ret = 0;
235
236 key_put(old);
237 error:
238 return ret;
239
240} /* end install_session_keyring() */
241
242/*****************************************************************************/
243/*
244 * copy the keys in a thread group for fork without CLONE_THREAD
245 */
246int copy_thread_group_keys(struct task_struct *tsk)
247{
248 unsigned long flags;
249
250 key_check(current->thread_group->session_keyring);
251 key_check(current->thread_group->process_keyring);
252
253 /* no process keyring yet */
254 tsk->signal->process_keyring = NULL;
255
256 /* same session keyring */
257 spin_lock_irqsave(&current->sighand->siglock, flags);
258 tsk->signal->session_keyring =
259 key_get(current->signal->session_keyring);
260 spin_unlock_irqrestore(&current->sighand->siglock, flags);
261
262 return 0;
263
264} /* end copy_thread_group_keys() */
265
266/*****************************************************************************/
267/*
268 * copy the keys for fork
269 */
270int copy_keys(unsigned long clone_flags, struct task_struct *tsk)
271{
272 key_check(tsk->thread_keyring);
273
274 /* no thread keyring yet */
275 tsk->thread_keyring = NULL;
276 return 0;
277
278} /* end copy_keys() */
279
280/*****************************************************************************/
281/*
282 * dispose of thread group keys upon thread group destruction
283 */
284void exit_thread_group_keys(struct signal_struct *tg)
285{
286 key_put(tg->session_keyring);
287 key_put(tg->process_keyring);
288
289} /* end exit_thread_group_keys() */
290
291/*****************************************************************************/
292/*
293 * dispose of keys upon thread exit
294 */
295void exit_keys(struct task_struct *tsk)
296{
297 key_put(tsk->thread_keyring);
298
299} /* end exit_keys() */
300
301/*****************************************************************************/
302/*
303 * deal with execve()
304 */
305int exec_keys(struct task_struct *tsk)
306{
307 unsigned long flags;
308 struct key *old;
309
310 /* newly exec'd tasks don't get a thread keyring */
311 task_lock(tsk);
312 old = tsk->thread_keyring;
313 tsk->thread_keyring = NULL;
314 task_unlock(tsk);
315
316 key_put(old);
317
318 /* discard the process keyring from a newly exec'd task */
319 spin_lock_irqsave(&tsk->sighand->siglock, flags);
320 old = tsk->signal->process_keyring;
321 tsk->signal->process_keyring = NULL;
322 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
323
324 key_put(old);
325
326 return 0;
327
328} /* end exec_keys() */
329
330/*****************************************************************************/
331/*
332 * deal with SUID programs
333 * - we might want to make this invent a new session keyring
334 */
335int suid_keys(struct task_struct *tsk)
336{
337 return 0;
338
339} /* end suid_keys() */
340
341/*****************************************************************************/
342/*
343 * the filesystem user ID changed
344 */
345void key_fsuid_changed(struct task_struct *tsk)
346{
347 /* update the ownership of the thread keyring */
348 if (tsk->thread_keyring) {
349 down_write(&tsk->thread_keyring->sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 tsk->thread_keyring->uid = tsk->fsuid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 up_write(&tsk->thread_keyring->sem);
352 }
353
354} /* end key_fsuid_changed() */
355
356/*****************************************************************************/
357/*
358 * the filesystem group ID changed
359 */
360void key_fsgid_changed(struct task_struct *tsk)
361{
362 /* update the ownership of the thread keyring */
363 if (tsk->thread_keyring) {
364 down_write(&tsk->thread_keyring->sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 tsk->thread_keyring->gid = tsk->fsgid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 up_write(&tsk->thread_keyring->sem);
367 }
368
369} /* end key_fsgid_changed() */
370
371/*****************************************************************************/
372/*
373 * search the process keyrings for the first matching key
374 * - we use the supplied match function to see if the description (or other
375 * feature of interest) matches
376 * - we return -EAGAIN if we didn't find any matching key
377 * - we return -ENOKEY if we found only negative matching keys
378 */
379struct key *search_process_keyrings_aux(struct key_type *type,
380 const void *description,
381 key_match_func_t match)
382{
383 struct task_struct *tsk = current;
384 unsigned long flags;
385 struct key *key, *ret, *err, *tmp;
386
387 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
388 * searchable, but we failed to find a key or we found a negative key;
389 * otherwise we want to return a sample error (probably -EACCES) if
390 * none of the keyrings were searchable
391 *
392 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
393 */
394 key = NULL;
395 ret = NULL;
396 err = ERR_PTR(-EAGAIN);
397
398 /* search the thread keyring first */
399 if (tsk->thread_keyring) {
400 key = keyring_search_aux(tsk->thread_keyring, type,
401 description, match);
402 if (!IS_ERR(key))
403 goto found;
404
405 switch (PTR_ERR(key)) {
406 case -EAGAIN: /* no key */
407 if (ret)
408 break;
409 case -ENOKEY: /* negative key */
410 ret = key;
411 break;
412 default:
413 err = key;
414 break;
415 }
416 }
417
418 /* search the process keyring second */
419 if (tsk->signal->process_keyring) {
420 key = keyring_search_aux(tsk->signal->process_keyring,
421 type, description, match);
422 if (!IS_ERR(key))
423 goto found;
424
425 switch (PTR_ERR(key)) {
426 case -EAGAIN: /* no key */
427 if (ret)
428 break;
429 case -ENOKEY: /* negative key */
430 ret = key;
431 break;
432 default:
433 err = key;
434 break;
435 }
436 }
437
438 /* search the session keyring last */
439 spin_lock_irqsave(&tsk->sighand->siglock, flags);
440
441 tmp = tsk->signal->session_keyring;
442 if (!tmp)
443 tmp = tsk->user->session_keyring;
444 atomic_inc(&tmp->usage);
445
446 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
447
448 key = keyring_search_aux(tmp, type, description, match);
449 key_put(tmp);
450 if (!IS_ERR(key))
451 goto found;
452
453 switch (PTR_ERR(key)) {
454 case -EAGAIN: /* no key */
455 if (ret)
456 break;
457 case -ENOKEY: /* negative key */
458 ret = key;
459 break;
460 default:
461 err = key;
462 break;
463 }
464
465 /* no key - decide on the error we're going to go for */
466 key = ret ? ret : err;
467
468 found:
469 return key;
470
471} /* end search_process_keyrings_aux() */
472
473/*****************************************************************************/
474/*
475 * search the process keyrings for the first matching key
476 * - we return -EAGAIN if we didn't find any matching key
477 * - we return -ENOKEY if we found only negative matching keys
478 */
479struct key *search_process_keyrings(struct key_type *type,
480 const char *description)
481{
482 return search_process_keyrings_aux(type, description, type->match);
483
484} /* end search_process_keyrings() */
485
486/*****************************************************************************/
487/*
488 * lookup a key given a key ID from userspace with a given permissions mask
489 * - don't create special keyrings unless so requested
490 * - partially constructed keys aren't found unless requested
491 */
492struct key *lookup_user_key(key_serial_t id, int create, int partial,
493 key_perm_t perm)
494{
495 struct task_struct *tsk = current;
496 unsigned long flags;
497 struct key *key;
498 int ret;
499
500 key = ERR_PTR(-ENOKEY);
501
502 switch (id) {
503 case KEY_SPEC_THREAD_KEYRING:
504 if (!tsk->thread_keyring) {
505 if (!create)
506 goto error;
507
508 ret = install_thread_keyring(tsk);
509 if (ret < 0) {
510 key = ERR_PTR(ret);
511 goto error;
512 }
513 }
514
515 key = tsk->thread_keyring;
516 atomic_inc(&key->usage);
517 break;
518
519 case KEY_SPEC_PROCESS_KEYRING:
520 if (!tsk->signal->process_keyring) {
521 if (!create)
522 goto error;
523
524 ret = install_process_keyring(tsk);
525 if (ret < 0) {
526 key = ERR_PTR(ret);
527 goto error;
528 }
529 }
530
531 key = tsk->signal->process_keyring;
532 atomic_inc(&key->usage);
533 break;
534
535 case KEY_SPEC_SESSION_KEYRING:
536 if (!tsk->signal->session_keyring) {
537 /* always install a session keyring upon access if one
538 * doesn't exist yet */
539 ret = install_session_keyring(
540 tsk, tsk->user->session_keyring);
541 if (ret < 0)
542 goto error;
543 }
544
545 spin_lock_irqsave(&tsk->sighand->siglock, flags);
546 key = tsk->signal->session_keyring;
547 atomic_inc(&key->usage);
548 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
549 break;
550
551 case KEY_SPEC_USER_KEYRING:
552 key = tsk->user->uid_keyring;
553 atomic_inc(&key->usage);
554 break;
555
556 case KEY_SPEC_USER_SESSION_KEYRING:
557 key = tsk->user->session_keyring;
558 atomic_inc(&key->usage);
559 break;
560
561 case KEY_SPEC_GROUP_KEYRING:
562 /* group keyrings are not yet supported */
563 key = ERR_PTR(-EINVAL);
564 goto error;
565
566 default:
567 key = ERR_PTR(-EINVAL);
568 if (id < 1)
569 goto error;
570
571 key = key_lookup(id);
572 if (IS_ERR(key))
573 goto error;
574 break;
575 }
576
577 /* check the status and permissions */
578 if (perm) {
579 ret = key_validate(key);
580 if (ret < 0)
581 goto invalid_key;
582 }
583
584 ret = -EIO;
David Howells76d8aea2005-06-23 22:00:49 -0700585 if (!partial && !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 goto invalid_key;
587
588 ret = -EACCES;
589 if (!key_permission(key, perm))
590 goto invalid_key;
591
592 error:
593 return key;
594
595 invalid_key:
596 key_put(key);
597 key = ERR_PTR(ret);
598 goto error;
599
600} /* end lookup_user_key() */
601
602/*****************************************************************************/
603/*
604 * join the named keyring as the session keyring if possible, or attempt to
605 * create a new one of that name if not
606 * - if the name is NULL, an empty anonymous keyring is installed instead
607 * - named session keyring joining is done with a semaphore held
608 */
609long join_session_keyring(const char *name)
610{
611 struct task_struct *tsk = current;
612 unsigned long flags;
613 struct key *keyring;
614 long ret;
615
616 /* if no name is provided, install an anonymous keyring */
617 if (!name) {
618 ret = install_session_keyring(tsk, NULL);
619 if (ret < 0)
620 goto error;
621
622 spin_lock_irqsave(&tsk->sighand->siglock, flags);
623 ret = tsk->signal->session_keyring->serial;
624 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
625 goto error;
626 }
627
628 /* allow the user to join or create a named keyring */
629 down(&key_session_sem);
630
631 /* look for an existing keyring of this name */
632 keyring = find_keyring_by_name(name, 0);
633 if (PTR_ERR(keyring) == -ENOKEY) {
634 /* not found - try and create a new one */
635 keyring = keyring_alloc(name, tsk->uid, tsk->gid, 0, NULL);
636 if (IS_ERR(keyring)) {
637 ret = PTR_ERR(keyring);
638 goto error;
639 }
640 }
641 else if (IS_ERR(keyring)) {
642 ret = PTR_ERR(keyring);
643 goto error2;
644 }
645
646 /* we've got a keyring - now to install it */
647 ret = install_session_keyring(tsk, keyring);
648 if (ret < 0)
649 goto error2;
650
651 ret = keyring->serial;
652 key_put(keyring);
653
654 error2:
655 up(&key_session_sem);
656 error:
657 return ret;
658
659} /* end join_session_keyring() */