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1/* Task credentials management - see Documentation/credentials.txt
2 *
3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells ([email protected])
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11#include <linux/module.h>
12#include <linux/cred.h>
13#include <linux/slab.h>
14#include <linux/sched.h>
15#include <linux/key.h>
16#include <linux/keyctl.h>
17#include <linux/init_task.h>
18#include <linux/security.h>
19#include <linux/cn_proc.h>
20#include "cred-internals.h"
21
22#if 0
23#define kdebug(FMT, ...) \
24 printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
25#else
26static inline __attribute__((format(printf, 1, 2)))
27void no_printk(const char *fmt, ...)
28{
29}
30#define kdebug(FMT, ...) \
31 no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
32#endif
33
34static struct kmem_cache *cred_jar;
35
36/*
37 * The common credentials for the initial task's thread group
38 */
39#ifdef CONFIG_KEYS
40static struct thread_group_cred init_tgcred = {
41 .usage = ATOMIC_INIT(2),
42 .tgid = 0,
43 .lock = SPIN_LOCK_UNLOCKED,
44};
45#endif
46
47/*
48 * The initial credentials for the initial task
49 */
50struct cred init_cred = {
51 .usage = ATOMIC_INIT(4),
52#ifdef CONFIG_DEBUG_CREDENTIALS
53 .subscribers = ATOMIC_INIT(2),
54 .magic = CRED_MAGIC,
55#endif
56 .securebits = SECUREBITS_DEFAULT,
57 .cap_inheritable = CAP_INIT_INH_SET,
58 .cap_permitted = CAP_FULL_SET,
59 .cap_effective = CAP_INIT_EFF_SET,
60 .cap_bset = CAP_INIT_BSET,
61 .user = INIT_USER,
62 .group_info = &init_groups,
63#ifdef CONFIG_KEYS
64 .tgcred = &init_tgcred,
65#endif
66};
67
68static inline void set_cred_subscribers(struct cred *cred, int n)
69{
70#ifdef CONFIG_DEBUG_CREDENTIALS
71 atomic_set(&cred->subscribers, n);
72#endif
73}
74
75static inline int read_cred_subscribers(const struct cred *cred)
76{
77#ifdef CONFIG_DEBUG_CREDENTIALS
78 return atomic_read(&cred->subscribers);
79#else
80 return 0;
81#endif
82}
83
84static inline void alter_cred_subscribers(const struct cred *_cred, int n)
85{
86#ifdef CONFIG_DEBUG_CREDENTIALS
87 struct cred *cred = (struct cred *) _cred;
88
89 atomic_add(n, &cred->subscribers);
90#endif
91}
92
93/*
94 * Dispose of the shared task group credentials
95 */
96#ifdef CONFIG_KEYS
97static void release_tgcred_rcu(struct rcu_head *rcu)
98{
99 struct thread_group_cred *tgcred =
100 container_of(rcu, struct thread_group_cred, rcu);
101
102 BUG_ON(atomic_read(&tgcred->usage) != 0);
103
104 key_put(tgcred->session_keyring);
105 key_put(tgcred->process_keyring);
106 kfree(tgcred);
107}
108#endif
109
110/*
111 * Release a set of thread group credentials.
112 */
113static void release_tgcred(struct cred *cred)
114{
115#ifdef CONFIG_KEYS
116 struct thread_group_cred *tgcred = cred->tgcred;
117
118 if (atomic_dec_and_test(&tgcred->usage))
119 call_rcu(&tgcred->rcu, release_tgcred_rcu);
120#endif
121}
122
123/*
124 * The RCU callback to actually dispose of a set of credentials
125 */
126static void put_cred_rcu(struct rcu_head *rcu)
127{
128 struct cred *cred = container_of(rcu, struct cred, rcu);
129
130 kdebug("put_cred_rcu(%p)", cred);
131
132#ifdef CONFIG_DEBUG_CREDENTIALS
133 if (cred->magic != CRED_MAGIC_DEAD ||
134 atomic_read(&cred->usage) != 0 ||
135 read_cred_subscribers(cred) != 0)
136 panic("CRED: put_cred_rcu() sees %p with"
137 " mag %x, put %p, usage %d, subscr %d\n",
138 cred, cred->magic, cred->put_addr,
139 atomic_read(&cred->usage),
140 read_cred_subscribers(cred));
141#else
142 if (atomic_read(&cred->usage) != 0)
143 panic("CRED: put_cred_rcu() sees %p with usage %d\n",
144 cred, atomic_read(&cred->usage));
145#endif
146
147 security_cred_free(cred);
148 key_put(cred->thread_keyring);
149 key_put(cred->request_key_auth);
150 release_tgcred(cred);
151 if (cred->group_info)
152 put_group_info(cred->group_info);
153 free_uid(cred->user);
154 kmem_cache_free(cred_jar, cred);
155}
156
157/**
158 * __put_cred - Destroy a set of credentials
159 * @cred: The record to release
160 *
161 * Destroy a set of credentials on which no references remain.
162 */
163void __put_cred(struct cred *cred)
164{
165 kdebug("__put_cred(%p{%d,%d})", cred,
166 atomic_read(&cred->usage),
167 read_cred_subscribers(cred));
168
169 BUG_ON(atomic_read(&cred->usage) != 0);
170#ifdef CONFIG_DEBUG_CREDENTIALS
171 BUG_ON(read_cred_subscribers(cred) != 0);
172 cred->magic = CRED_MAGIC_DEAD;
173 cred->put_addr = __builtin_return_address(0);
174#endif
175 BUG_ON(cred == current->cred);
176 BUG_ON(cred == current->real_cred);
177
178 call_rcu(&cred->rcu, put_cred_rcu);
179}
180EXPORT_SYMBOL(__put_cred);
181
182/*
183 * Clean up a task's credentials when it exits
184 */
185void exit_creds(struct task_struct *tsk)
186{
187 struct cred *cred;
188
189 kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
190 atomic_read(&tsk->cred->usage),
191 read_cred_subscribers(tsk->cred));
192
193 cred = (struct cred *) tsk->real_cred;
194 tsk->real_cred = NULL;
195 validate_creds(cred);
196 alter_cred_subscribers(cred, -1);
197 put_cred(cred);
198
199 cred = (struct cred *) tsk->cred;
200 tsk->cred = NULL;
201 validate_creds(cred);
202 alter_cred_subscribers(cred, -1);
203 put_cred(cred);
204
205 cred = (struct cred *) tsk->replacement_session_keyring;
206 if (cred) {
207 tsk->replacement_session_keyring = NULL;
208 validate_creds(cred);
209 put_cred(cred);
210 }
211}
212
213/*
214 * Allocate blank credentials, such that the credentials can be filled in at a
215 * later date without risk of ENOMEM.
216 */
217struct cred *cred_alloc_blank(void)
218{
219 struct cred *new;
220
221 new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
222 if (!new)
223 return NULL;
224
225#ifdef CONFIG_KEYS
226 new->tgcred = kzalloc(sizeof(*new->tgcred), GFP_KERNEL);
227 if (!new->tgcred) {
228 kmem_cache_free(cred_jar, new);
229 return NULL;
230 }
231 atomic_set(&new->tgcred->usage, 1);
232#endif
233
234 atomic_set(&new->usage, 1);
235
236 if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
237 goto error;
238
239#ifdef CONFIG_DEBUG_CREDENTIALS
240 new->magic = CRED_MAGIC;
241#endif
242 return new;
243
244error:
245 abort_creds(new);
246 return NULL;
247}
248
249/**
250 * prepare_creds - Prepare a new set of credentials for modification
251 *
252 * Prepare a new set of task credentials for modification. A task's creds
253 * shouldn't generally be modified directly, therefore this function is used to
254 * prepare a new copy, which the caller then modifies and then commits by
255 * calling commit_creds().
256 *
257 * Preparation involves making a copy of the objective creds for modification.
258 *
259 * Returns a pointer to the new creds-to-be if successful, NULL otherwise.
260 *
261 * Call commit_creds() or abort_creds() to clean up.
262 */
263struct cred *prepare_creds(void)
264{
265 struct task_struct *task = current;
266 const struct cred *old;
267 struct cred *new;
268
269 validate_process_creds();
270
271 new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
272 if (!new)
273 return NULL;
274
275 kdebug("prepare_creds() alloc %p", new);
276
277 old = task->cred;
278 memcpy(new, old, sizeof(struct cred));
279
280 atomic_set(&new->usage, 1);
281 set_cred_subscribers(new, 0);
282 get_group_info(new->group_info);
283 get_uid(new->user);
284
285#ifdef CONFIG_KEYS
286 key_get(new->thread_keyring);
287 key_get(new->request_key_auth);
288 atomic_inc(&new->tgcred->usage);
289#endif
290
291#ifdef CONFIG_SECURITY
292 new->security = NULL;
293#endif
294
295 if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
296 goto error;
297 validate_creds(new);
298 return new;
299
300error:
301 abort_creds(new);
302 return NULL;
303}
304EXPORT_SYMBOL(prepare_creds);
305
306/*
307 * Prepare credentials for current to perform an execve()
308 * - The caller must hold current->cred_guard_mutex
309 */
310struct cred *prepare_exec_creds(void)
311{
312 struct thread_group_cred *tgcred = NULL;
313 struct cred *new;
314
315#ifdef CONFIG_KEYS
316 tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
317 if (!tgcred)
318 return NULL;
319#endif
320
321 new = prepare_creds();
322 if (!new) {
323 kfree(tgcred);
324 return new;
325 }
326
327#ifdef CONFIG_KEYS
328 /* newly exec'd tasks don't get a thread keyring */
329 key_put(new->thread_keyring);
330 new->thread_keyring = NULL;
331
332 /* create a new per-thread-group creds for all this set of threads to
333 * share */
334 memcpy(tgcred, new->tgcred, sizeof(struct thread_group_cred));
335
336 atomic_set(&tgcred->usage, 1);
337 spin_lock_init(&tgcred->lock);
338
339 /* inherit the session keyring; new process keyring */
340 key_get(tgcred->session_keyring);
341 tgcred->process_keyring = NULL;
342
343 release_tgcred(new);
344 new->tgcred = tgcred;
345#endif
346
347 return new;
348}
349
350/*
351 * prepare new credentials for the usermode helper dispatcher
352 */
353struct cred *prepare_usermodehelper_creds(void)
354{
355#ifdef CONFIG_KEYS
356 struct thread_group_cred *tgcred = NULL;
357#endif
358 struct cred *new;
359
360#ifdef CONFIG_KEYS
361 tgcred = kzalloc(sizeof(*new->tgcred), GFP_ATOMIC);
362 if (!tgcred)
363 return NULL;
364#endif
365
366 new = kmem_cache_alloc(cred_jar, GFP_ATOMIC);
367 if (!new)
368 goto free_tgcred;
369
370 kdebug("prepare_usermodehelper_creds() alloc %p", new);
371
372 memcpy(new, &init_cred, sizeof(struct cred));
373
374 atomic_set(&new->usage, 1);
375 set_cred_subscribers(new, 0);
376 get_group_info(new->group_info);
377 get_uid(new->user);
378
379#ifdef CONFIG_KEYS
380 new->thread_keyring = NULL;
381 new->request_key_auth = NULL;
382 new->jit_keyring = KEY_REQKEY_DEFL_DEFAULT;
383
384 atomic_set(&tgcred->usage, 1);
385 spin_lock_init(&tgcred->lock);
386 new->tgcred = tgcred;
387#endif
388
389#ifdef CONFIG_SECURITY
390 new->security = NULL;
391#endif
392 if (security_prepare_creds(new, &init_cred, GFP_ATOMIC) < 0)
393 goto error;
394 validate_creds(new);
395
396 BUG_ON(atomic_read(&new->usage) != 1);
397 return new;
398
399error:
400 put_cred(new);
401 return NULL;
402
403free_tgcred:
404#ifdef CONFIG_KEYS
405 kfree(tgcred);
406#endif
407 return NULL;
408}
409
410/*
411 * Copy credentials for the new process created by fork()
412 *
413 * We share if we can, but under some circumstances we have to generate a new
414 * set.
415 *
416 * The new process gets the current process's subjective credentials as its
417 * objective and subjective credentials
418 */
419int copy_creds(struct task_struct *p, unsigned long clone_flags)
420{
421#ifdef CONFIG_KEYS
422 struct thread_group_cred *tgcred;
423#endif
424 struct cred *new;
425 int ret;
426
427 mutex_init(&p->cred_guard_mutex);
428
429 if (
430#ifdef CONFIG_KEYS
431 !p->cred->thread_keyring &&
432#endif
433 clone_flags & CLONE_THREAD
434 ) {
435 p->real_cred = get_cred(p->cred);
436 get_cred(p->cred);
437 alter_cred_subscribers(p->cred, 2);
438 kdebug("share_creds(%p{%d,%d})",
439 p->cred, atomic_read(&p->cred->usage),
440 read_cred_subscribers(p->cred));
441 atomic_inc(&p->cred->user->processes);
442 return 0;
443 }
444
445 new = prepare_creds();
446 if (!new)
447 return -ENOMEM;
448
449 if (clone_flags & CLONE_NEWUSER) {
450 ret = create_user_ns(new);
451 if (ret < 0)
452 goto error_put;
453 }
454
455#ifdef CONFIG_KEYS
456 /* new threads get their own thread keyrings if their parent already
457 * had one */
458 if (new->thread_keyring) {
459 key_put(new->thread_keyring);
460 new->thread_keyring = NULL;
461 if (clone_flags & CLONE_THREAD)
462 install_thread_keyring_to_cred(new);
463 }
464
465 /* we share the process and session keyrings between all the threads in
466 * a process - this is slightly icky as we violate COW credentials a
467 * bit */
468 if (!(clone_flags & CLONE_THREAD)) {
469 tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
470 if (!tgcred) {
471 ret = -ENOMEM;
472 goto error_put;
473 }
474 atomic_set(&tgcred->usage, 1);
475 spin_lock_init(&tgcred->lock);
476 tgcred->process_keyring = NULL;
477 tgcred->session_keyring = key_get(new->tgcred->session_keyring);
478
479 release_tgcred(new);
480 new->tgcred = tgcred;
481 }
482#endif
483
484 atomic_inc(&new->user->processes);
485 p->cred = p->real_cred = get_cred(new);
486 alter_cred_subscribers(new, 2);
487 validate_creds(new);
488 return 0;
489
490error_put:
491 put_cred(new);
492 return ret;
493}
494
495/**
496 * commit_creds - Install new credentials upon the current task
497 * @new: The credentials to be assigned
498 *
499 * Install a new set of credentials to the current task, using RCU to replace
500 * the old set. Both the objective and the subjective credentials pointers are
501 * updated. This function may not be called if the subjective credentials are
502 * in an overridden state.
503 *
504 * This function eats the caller's reference to the new credentials.
505 *
506 * Always returns 0 thus allowing this function to be tail-called at the end
507 * of, say, sys_setgid().
508 */
509int commit_creds(struct cred *new)
510{
511 struct task_struct *task = current;
512 const struct cred *old = task->real_cred;
513
514 kdebug("commit_creds(%p{%d,%d})", new,
515 atomic_read(&new->usage),
516 read_cred_subscribers(new));
517
518 BUG_ON(task->cred != old);
519#ifdef CONFIG_DEBUG_CREDENTIALS
520 BUG_ON(read_cred_subscribers(old) < 2);
521 validate_creds(old);
522 validate_creds(new);
523#endif
524 BUG_ON(atomic_read(&new->usage) < 1);
525
526 security_commit_creds(new, old);
527
528 get_cred(new); /* we will require a ref for the subj creds too */
529
530 /* dumpability changes */
531 if (old->euid != new->euid ||
532 old->egid != new->egid ||
533 old->fsuid != new->fsuid ||
534 old->fsgid != new->fsgid ||
535 !cap_issubset(new->cap_permitted, old->cap_permitted)) {
536 if (task->mm)
537 set_dumpable(task->mm, suid_dumpable);
538 task->pdeath_signal = 0;
539 smp_wmb();
540 }
541
542 /* alter the thread keyring */
543 if (new->fsuid != old->fsuid)
544 key_fsuid_changed(task);
545 if (new->fsgid != old->fsgid)
546 key_fsgid_changed(task);
547
548 /* do it
549 * - What if a process setreuid()'s and this brings the
550 * new uid over his NPROC rlimit? We can check this now
551 * cheaply with the new uid cache, so if it matters
552 * we should be checking for it. -DaveM
553 */
554 alter_cred_subscribers(new, 2);
555 if (new->user != old->user)
556 atomic_inc(&new->user->processes);
557 rcu_assign_pointer(task->real_cred, new);
558 rcu_assign_pointer(task->cred, new);
559 if (new->user != old->user)
560 atomic_dec(&old->user->processes);
561 alter_cred_subscribers(old, -2);
562
563 sched_switch_user(task);
564
565 /* send notifications */
566 if (new->uid != old->uid ||
567 new->euid != old->euid ||
568 new->suid != old->suid ||
569 new->fsuid != old->fsuid)
570 proc_id_connector(task, PROC_EVENT_UID);
571
572 if (new->gid != old->gid ||
573 new->egid != old->egid ||
574 new->sgid != old->sgid ||
575 new->fsgid != old->fsgid)
576 proc_id_connector(task, PROC_EVENT_GID);
577
578 /* release the old obj and subj refs both */
579 put_cred(old);
580 put_cred(old);
581 return 0;
582}
583EXPORT_SYMBOL(commit_creds);
584
585/**
586 * abort_creds - Discard a set of credentials and unlock the current task
587 * @new: The credentials that were going to be applied
588 *
589 * Discard a set of credentials that were under construction and unlock the
590 * current task.
591 */
592void abort_creds(struct cred *new)
593{
594 kdebug("abort_creds(%p{%d,%d})", new,
595 atomic_read(&new->usage),
596 read_cred_subscribers(new));
597
598#ifdef CONFIG_DEBUG_CREDENTIALS
599 BUG_ON(read_cred_subscribers(new) != 0);
600#endif
601 BUG_ON(atomic_read(&new->usage) < 1);
602 put_cred(new);
603}
604EXPORT_SYMBOL(abort_creds);
605
606/**
607 * override_creds - Override the current process's subjective credentials
608 * @new: The credentials to be assigned
609 *
610 * Install a set of temporary override subjective credentials on the current
611 * process, returning the old set for later reversion.
612 */
613const struct cred *override_creds(const struct cred *new)
614{
615 const struct cred *old = current->cred;
616
617 kdebug("override_creds(%p{%d,%d})", new,
618 atomic_read(&new->usage),
619 read_cred_subscribers(new));
620
621 validate_creds(old);
622 validate_creds(new);
623 get_cred(new);
624 alter_cred_subscribers(new, 1);
625 rcu_assign_pointer(current->cred, new);
626 alter_cred_subscribers(old, -1);
627
628 kdebug("override_creds() = %p{%d,%d}", old,
629 atomic_read(&old->usage),
630 read_cred_subscribers(old));
631 return old;
632}
633EXPORT_SYMBOL(override_creds);
634
635/**
636 * revert_creds - Revert a temporary subjective credentials override
637 * @old: The credentials to be restored
638 *
639 * Revert a temporary set of override subjective credentials to an old set,
640 * discarding the override set.
641 */
642void revert_creds(const struct cred *old)
643{
644 const struct cred *override = current->cred;
645
646 kdebug("revert_creds(%p{%d,%d})", old,
647 atomic_read(&old->usage),
648 read_cred_subscribers(old));
649
650 validate_creds(old);
651 validate_creds(override);
652 alter_cred_subscribers(old, 1);
653 rcu_assign_pointer(current->cred, old);
654 alter_cred_subscribers(override, -1);
655 put_cred(override);
656}
657EXPORT_SYMBOL(revert_creds);
658
659/*
660 * initialise the credentials stuff
661 */
662void __init cred_init(void)
663{
664 /* allocate a slab in which we can store credentials */
665 cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred),
666 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
667}
668
669/**
670 * prepare_kernel_cred - Prepare a set of credentials for a kernel service
671 * @daemon: A userspace daemon to be used as a reference
672 *
673 * Prepare a set of credentials for a kernel service. This can then be used to
674 * override a task's own credentials so that work can be done on behalf of that
675 * task that requires a different subjective context.
676 *
677 * @daemon is used to provide a base for the security record, but can be NULL.
678 * If @daemon is supplied, then the security data will be derived from that;
679 * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
680 *
681 * The caller may change these controls afterwards if desired.
682 *
683 * Returns the new credentials or NULL if out of memory.
684 *
685 * Does not take, and does not return holding current->cred_replace_mutex.
686 */
687struct cred *prepare_kernel_cred(struct task_struct *daemon)
688{
689 const struct cred *old;
690 struct cred *new;
691
692 new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
693 if (!new)
694 return NULL;
695
696 kdebug("prepare_kernel_cred() alloc %p", new);
697
698 if (daemon)
699 old = get_task_cred(daemon);
700 else
701 old = get_cred(&init_cred);
702
703 validate_creds(old);
704
705 *new = *old;
706 get_uid(new->user);
707 get_group_info(new->group_info);
708
709#ifdef CONFIG_KEYS
710 atomic_inc(&init_tgcred.usage);
711 new->tgcred = &init_tgcred;
712 new->request_key_auth = NULL;
713 new->thread_keyring = NULL;
714 new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
715#endif
716
717#ifdef CONFIG_SECURITY
718 new->security = NULL;
719#endif
720 if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
721 goto error;
722
723 atomic_set(&new->usage, 1);
724 set_cred_subscribers(new, 0);
725 put_cred(old);
726 validate_creds(new);
727 return new;
728
729error:
730 put_cred(new);
731 put_cred(old);
732 return NULL;
733}
734EXPORT_SYMBOL(prepare_kernel_cred);
735
736/**
737 * set_security_override - Set the security ID in a set of credentials
738 * @new: The credentials to alter
739 * @secid: The LSM security ID to set
740 *
741 * Set the LSM security ID in a set of credentials so that the subjective
742 * security is overridden when an alternative set of credentials is used.
743 */
744int set_security_override(struct cred *new, u32 secid)
745{
746 return security_kernel_act_as(new, secid);
747}
748EXPORT_SYMBOL(set_security_override);
749
750/**
751 * set_security_override_from_ctx - Set the security ID in a set of credentials
752 * @new: The credentials to alter
753 * @secctx: The LSM security context to generate the security ID from.
754 *
755 * Set the LSM security ID in a set of credentials so that the subjective
756 * security is overridden when an alternative set of credentials is used. The
757 * security ID is specified in string form as a security context to be
758 * interpreted by the LSM.
759 */
760int set_security_override_from_ctx(struct cred *new, const char *secctx)
761{
762 u32 secid;
763 int ret;
764
765 ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
766 if (ret < 0)
767 return ret;
768
769 return set_security_override(new, secid);
770}
771EXPORT_SYMBOL(set_security_override_from_ctx);
772
773/**
774 * set_create_files_as - Set the LSM file create context in a set of credentials
775 * @new: The credentials to alter
776 * @inode: The inode to take the context from
777 *
778 * Change the LSM file creation context in a set of credentials to be the same
779 * as the object context of the specified inode, so that the new inodes have
780 * the same MAC context as that inode.
781 */
782int set_create_files_as(struct cred *new, struct inode *inode)
783{
784 new->fsuid = inode->i_uid;
785 new->fsgid = inode->i_gid;
786 return security_kernel_create_files_as(new, inode);
787}
788EXPORT_SYMBOL(set_create_files_as);
789
790#ifdef CONFIG_DEBUG_CREDENTIALS
791
792bool creds_are_invalid(const struct cred *cred)
793{
794 if (cred->magic != CRED_MAGIC)
795 return true;
796#ifdef CONFIG_SECURITY_SELINUX
797 if (selinux_is_enabled()) {
798 if ((unsigned long) cred->security < PAGE_SIZE)
799 return true;
800 if ((*(u32 *)cred->security & 0xffffff00) ==
801 (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
802 return true;
803 }
804#endif
805 return false;
806}
807EXPORT_SYMBOL(creds_are_invalid);
808
809/*
810 * dump invalid credentials
811 */
812static void dump_invalid_creds(const struct cred *cred, const char *label,
813 const struct task_struct *tsk)
814{
815 printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
816 label, cred,
817 cred == &init_cred ? "[init]" : "",
818 cred == tsk->real_cred ? "[real]" : "",
819 cred == tsk->cred ? "[eff]" : "");
820 printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
821 cred->magic, cred->put_addr);
822 printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
823 atomic_read(&cred->usage),
824 read_cred_subscribers(cred));
825 printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
826 cred->uid, cred->euid, cred->suid, cred->fsuid);
827 printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
828 cred->gid, cred->egid, cred->sgid, cred->fsgid);
829#ifdef CONFIG_SECURITY
830 printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
831 if ((unsigned long) cred->security >= PAGE_SIZE &&
832 (((unsigned long) cred->security & 0xffffff00) !=
833 (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
834 printk(KERN_ERR "CRED: ->security {%x, %x}\n",
835 ((u32*)cred->security)[0],
836 ((u32*)cred->security)[1]);
837#endif
838}
839
840/*
841 * report use of invalid credentials
842 */
843void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
844{
845 printk(KERN_ERR "CRED: Invalid credentials\n");
846 printk(KERN_ERR "CRED: At %s:%u\n", file, line);
847 dump_invalid_creds(cred, "Specified", current);
848 BUG();
849}
850EXPORT_SYMBOL(__invalid_creds);
851
852/*
853 * check the credentials on a process
854 */
855void __validate_process_creds(struct task_struct *tsk,
856 const char *file, unsigned line)
857{
858 if (tsk->cred == tsk->real_cred) {
859 if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
860 creds_are_invalid(tsk->cred)))
861 goto invalid_creds;
862 } else {
863 if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
864 read_cred_subscribers(tsk->cred) < 1 ||
865 creds_are_invalid(tsk->real_cred) ||
866 creds_are_invalid(tsk->cred)))
867 goto invalid_creds;
868 }
869 return;
870
871invalid_creds:
872 printk(KERN_ERR "CRED: Invalid process credentials\n");
873 printk(KERN_ERR "CRED: At %s:%u\n", file, line);
874
875 dump_invalid_creds(tsk->real_cred, "Real", tsk);
876 if (tsk->cred != tsk->real_cred)
877 dump_invalid_creds(tsk->cred, "Effective", tsk);
878 else
879 printk(KERN_ERR "CRED: Effective creds == Real creds\n");
880 BUG();
881}
882EXPORT_SYMBOL(__validate_process_creds);
883
884/*
885 * check creds for do_exit()
886 */
887void validate_creds_for_do_exit(struct task_struct *tsk)
888{
889 kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
890 tsk->real_cred, tsk->cred,
891 atomic_read(&tsk->cred->usage),
892 read_cred_subscribers(tsk->cred));
893
894 __validate_process_creds(tsk, __FILE__, __LINE__);
895}
896
897#endif /* CONFIG_DEBUG_CREDENTIALS */