1 /* process_keys.c: management of a process's keyrings
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
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>
18 #include <linux/err.h>
19 #include <asm/uaccess.h>
22 /* session keyring create vs join semaphore */
23 static DECLARE_MUTEX(key_session_sem);
25 /* the root user's tracking struct */
26 struct 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),
35 /* the root user's UID keyring */
36 struct key root_user_keyring = {
37 .usage = ATOMIC_INIT(1),
39 .type = &key_type_keyring,
40 .user = &root_key_user,
41 .sem = __RWSEM_INITIALIZER(root_user_keyring.sem),
43 .flags = 1 << KEY_FLAG_INSTANTIATED,
44 .description = "_uid.0",
46 .magic = KEY_DEBUG_MAGIC,
50 /* the root user's default session keyring */
51 struct key root_session_keyring = {
52 .usage = ATOMIC_INIT(1),
54 .type = &key_type_keyring,
55 .user = &root_key_user,
56 .sem = __RWSEM_INITIALIZER(root_session_keyring.sem),
58 .flags = 1 << KEY_FLAG_INSTANTIATED,
59 .description = "_uid_ses.0",
61 .magic = KEY_DEBUG_MAGIC,
65 /*****************************************************************************/
67 * allocate the keyrings to be associated with a UID
69 int alloc_uid_keyring(struct user_struct *user)
71 struct key *uid_keyring, *session_keyring;
75 /* concoct a default session keyring */
76 sprintf(buf, "_uid_ses.%u", user->uid);
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);
84 /* and a UID specific keyring, pointed to by the default session
86 sprintf(buf, "_uid.%u", user->uid);
88 uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, 0,
90 if (IS_ERR(uid_keyring)) {
91 key_put(session_keyring);
92 ret = PTR_ERR(uid_keyring);
96 /* install the keyrings */
97 user->uid_keyring = uid_keyring;
98 user->session_keyring = session_keyring;
104 } /* end alloc_uid_keyring() */
106 /*****************************************************************************/
108 * deal with the UID changing
110 void switch_uid_keyring(struct user_struct *new_user)
112 #if 0 /* do nothing for now */
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
120 atomic_inc(&new_user->session_keyring->usage);
123 old = current->session_keyring;
124 current->session_keyring = new_user->session_keyring;
125 task_unlock(current);
131 } /* end switch_uid_keyring() */
133 /*****************************************************************************/
135 * install a fresh thread keyring, discarding the old one
137 int install_thread_keyring(struct task_struct *tsk)
139 struct key *keyring, *old;
143 sprintf(buf, "_tid.%u", tsk->pid);
145 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
146 if (IS_ERR(keyring)) {
147 ret = PTR_ERR(keyring);
152 old = tsk->thread_keyring;
153 tsk->thread_keyring = keyring;
162 } /* end install_thread_keyring() */
164 /*****************************************************************************/
166 * make sure a process keyring is installed
168 static int install_process_keyring(struct task_struct *tsk)
175 if (!tsk->signal->process_keyring) {
176 sprintf(buf, "_pid.%u", tsk->tgid);
178 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
179 if (IS_ERR(keyring)) {
180 ret = PTR_ERR(keyring);
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;
190 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
199 } /* end install_process_keyring() */
201 /*****************************************************************************/
203 * install a session keyring, discarding the old one
204 * - if a keyring is not supplied, an empty one is invented
206 static int install_session_keyring(struct task_struct *tsk,
214 /* create an empty session keyring */
216 sprintf(buf, "_ses.%u", tsk->tgid);
218 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
219 if (IS_ERR(keyring)) {
220 ret = PTR_ERR(keyring);
225 atomic_inc(&keyring->usage);
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);
240 } /* end install_session_keyring() */
242 /*****************************************************************************/
244 * copy the keys in a thread group for fork without CLONE_THREAD
246 int copy_thread_group_keys(struct task_struct *tsk)
250 key_check(current->thread_group->session_keyring);
251 key_check(current->thread_group->process_keyring);
253 /* no process keyring yet */
254 tsk->signal->process_keyring = NULL;
256 /* same session keyring */
257 spin_lock_irqsave(¤t->sighand->siglock, flags);
258 tsk->signal->session_keyring =
259 key_get(current->signal->session_keyring);
260 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
264 } /* end copy_thread_group_keys() */
266 /*****************************************************************************/
268 * copy the keys for fork
270 int copy_keys(unsigned long clone_flags, struct task_struct *tsk)
272 key_check(tsk->thread_keyring);
274 /* no thread keyring yet */
275 tsk->thread_keyring = NULL;
278 } /* end copy_keys() */
280 /*****************************************************************************/
282 * dispose of thread group keys upon thread group destruction
284 void exit_thread_group_keys(struct signal_struct *tg)
286 key_put(tg->session_keyring);
287 key_put(tg->process_keyring);
289 } /* end exit_thread_group_keys() */
291 /*****************************************************************************/
293 * dispose of keys upon thread exit
295 void exit_keys(struct task_struct *tsk)
297 key_put(tsk->thread_keyring);
299 } /* end exit_keys() */
301 /*****************************************************************************/
305 int exec_keys(struct task_struct *tsk)
310 /* newly exec'd tasks don't get a thread keyring */
312 old = tsk->thread_keyring;
313 tsk->thread_keyring = NULL;
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);
328 } /* end exec_keys() */
330 /*****************************************************************************/
332 * deal with SUID programs
333 * - we might want to make this invent a new session keyring
335 int suid_keys(struct task_struct *tsk)
339 } /* end suid_keys() */
341 /*****************************************************************************/
343 * the filesystem user ID changed
345 void key_fsuid_changed(struct task_struct *tsk)
347 /* update the ownership of the thread keyring */
348 if (tsk->thread_keyring) {
349 down_write(&tsk->thread_keyring->sem);
350 tsk->thread_keyring->uid = tsk->fsuid;
351 up_write(&tsk->thread_keyring->sem);
354 } /* end key_fsuid_changed() */
356 /*****************************************************************************/
358 * the filesystem group ID changed
360 void key_fsgid_changed(struct task_struct *tsk)
362 /* update the ownership of the thread keyring */
363 if (tsk->thread_keyring) {
364 down_write(&tsk->thread_keyring->sem);
365 tsk->thread_keyring->gid = tsk->fsgid;
366 up_write(&tsk->thread_keyring->sem);
369 } /* end key_fsgid_changed() */
371 /*****************************************************************************/
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
379 struct key *search_process_keyrings_aux(struct key_type *type,
380 const void *description,
381 key_match_func_t match)
383 struct task_struct *tsk = current;
385 struct key *key, *ret, *err, *tmp;
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
392 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
396 err = ERR_PTR(-EAGAIN);
398 /* search the thread keyring first */
399 if (tsk->thread_keyring) {
400 key = keyring_search_aux(tsk->thread_keyring, type,
405 switch (PTR_ERR(key)) {
406 case -EAGAIN: /* no key */
409 case -ENOKEY: /* negative key */
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);
425 switch (PTR_ERR(key)) {
426 case -EAGAIN: /* no key */
429 case -ENOKEY: /* negative key */
438 /* search the session keyring last */
439 spin_lock_irqsave(&tsk->sighand->siglock, flags);
441 tmp = tsk->signal->session_keyring;
443 tmp = tsk->user->session_keyring;
444 atomic_inc(&tmp->usage);
446 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
448 key = keyring_search_aux(tmp, type, description, match);
453 switch (PTR_ERR(key)) {
454 case -EAGAIN: /* no key */
457 case -ENOKEY: /* negative key */
465 /* no key - decide on the error we're going to go for */
466 key = ret ? ret : err;
471 } /* end search_process_keyrings_aux() */
473 /*****************************************************************************/
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
479 struct key *search_process_keyrings(struct key_type *type,
480 const char *description)
482 return search_process_keyrings_aux(type, description, type->match);
484 } /* end search_process_keyrings() */
486 /*****************************************************************************/
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
492 struct key *lookup_user_key(key_serial_t id, int create, int partial,
495 struct task_struct *tsk = current;
500 key = ERR_PTR(-ENOKEY);
503 case KEY_SPEC_THREAD_KEYRING:
504 if (!tsk->thread_keyring) {
508 ret = install_thread_keyring(tsk);
515 key = tsk->thread_keyring;
516 atomic_inc(&key->usage);
519 case KEY_SPEC_PROCESS_KEYRING:
520 if (!tsk->signal->process_keyring) {
524 ret = install_process_keyring(tsk);
531 key = tsk->signal->process_keyring;
532 atomic_inc(&key->usage);
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);
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);
551 case KEY_SPEC_USER_KEYRING:
552 key = tsk->user->uid_keyring;
553 atomic_inc(&key->usage);
556 case KEY_SPEC_USER_SESSION_KEYRING:
557 key = tsk->user->session_keyring;
558 atomic_inc(&key->usage);
561 case KEY_SPEC_GROUP_KEYRING:
562 /* group keyrings are not yet supported */
563 key = ERR_PTR(-EINVAL);
567 key = ERR_PTR(-EINVAL);
571 key = key_lookup(id);
577 /* check the status and permissions */
579 ret = key_validate(key);
585 if (!partial && !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
589 if (!key_permission(key, perm))
600 } /* end lookup_user_key() */
602 /*****************************************************************************/
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
609 long join_session_keyring(const char *name)
611 struct task_struct *tsk = current;
616 /* if no name is provided, install an anonymous keyring */
618 ret = install_session_keyring(tsk, NULL);
622 spin_lock_irqsave(&tsk->sighand->siglock, flags);
623 ret = tsk->signal->session_keyring->serial;
624 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
628 /* allow the user to join or create a named keyring */
629 down(&key_session_sem);
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);
641 else if (IS_ERR(keyring)) {
642 ret = PTR_ERR(keyring);
646 /* we've got a keyring - now to install it */
647 ret = install_session_keyring(tsk, keyring);
651 ret = keyring->serial;
655 up(&key_session_sem);
659 } /* end join_session_keyring() */