kernel: power: qos: export qos routine
[linux-2.6.git] / kernel / cred.c
1 /* Task credentials management - see Documentation/security/credentials.txt
2  *
3  * Copyright (C) 2008 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 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/export.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/binfmts.h>
20 #include <linux/cn_proc.h>
21
22 #if 0
23 #define kdebug(FMT, ...) \
24         printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
25 #else
26 #define kdebug(FMT, ...) \
27         no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
28 #endif
29
30 static struct kmem_cache *cred_jar;
31
32 /*
33  * The common credentials for the initial task's thread group
34  */
35 #ifdef CONFIG_KEYS
36 static struct thread_group_cred init_tgcred = {
37         .usage  = ATOMIC_INIT(2),
38         .tgid   = 0,
39         .lock   = __SPIN_LOCK_UNLOCKED(init_cred.tgcred.lock),
40 };
41 #endif
42
43 /*
44  * The initial credentials for the initial task
45  */
46 struct cred init_cred = {
47         .usage                  = ATOMIC_INIT(4),
48 #ifdef CONFIG_DEBUG_CREDENTIALS
49         .subscribers            = ATOMIC_INIT(2),
50         .magic                  = CRED_MAGIC,
51 #endif
52         .securebits             = SECUREBITS_DEFAULT,
53         .cap_inheritable        = CAP_EMPTY_SET,
54         .cap_permitted          = CAP_FULL_SET,
55         .cap_effective          = CAP_FULL_SET,
56         .cap_bset               = CAP_FULL_SET,
57         .user                   = INIT_USER,
58         .user_ns                = &init_user_ns,
59         .group_info             = &init_groups,
60 #ifdef CONFIG_KEYS
61         .tgcred                 = &init_tgcred,
62 #endif
63 };
64
65 static inline void set_cred_subscribers(struct cred *cred, int n)
66 {
67 #ifdef CONFIG_DEBUG_CREDENTIALS
68         atomic_set(&cred->subscribers, n);
69 #endif
70 }
71
72 static inline int read_cred_subscribers(const struct cred *cred)
73 {
74 #ifdef CONFIG_DEBUG_CREDENTIALS
75         return atomic_read(&cred->subscribers);
76 #else
77         return 0;
78 #endif
79 }
80
81 static inline void alter_cred_subscribers(const struct cred *_cred, int n)
82 {
83 #ifdef CONFIG_DEBUG_CREDENTIALS
84         struct cred *cred = (struct cred *) _cred;
85
86         atomic_add(n, &cred->subscribers);
87 #endif
88 }
89
90 /*
91  * Dispose of the shared task group credentials
92  */
93 #ifdef CONFIG_KEYS
94 static void release_tgcred_rcu(struct rcu_head *rcu)
95 {
96         struct thread_group_cred *tgcred =
97                 container_of(rcu, struct thread_group_cred, rcu);
98
99         BUG_ON(atomic_read(&tgcred->usage) != 0);
100
101         key_put(tgcred->session_keyring);
102         key_put(tgcred->process_keyring);
103         kfree(tgcred);
104 }
105 #endif
106
107 /*
108  * Release a set of thread group credentials.
109  */
110 static void release_tgcred(struct cred *cred)
111 {
112 #ifdef CONFIG_KEYS
113         struct thread_group_cred *tgcred = cred->tgcred;
114
115         if (atomic_dec_and_test(&tgcred->usage))
116                 call_rcu(&tgcred->rcu, release_tgcred_rcu);
117 #endif
118 }
119
120 /*
121  * The RCU callback to actually dispose of a set of credentials
122  */
123 static void put_cred_rcu(struct rcu_head *rcu)
124 {
125         struct cred *cred = container_of(rcu, struct cred, rcu);
126
127         kdebug("put_cred_rcu(%p)", cred);
128
129 #ifdef CONFIG_DEBUG_CREDENTIALS
130         if (cred->magic != CRED_MAGIC_DEAD ||
131             atomic_read(&cred->usage) != 0 ||
132             read_cred_subscribers(cred) != 0)
133                 panic("CRED: put_cred_rcu() sees %p with"
134                       " mag %x, put %p, usage %d, subscr %d\n",
135                       cred, cred->magic, cred->put_addr,
136                       atomic_read(&cred->usage),
137                       read_cred_subscribers(cred));
138 #else
139         if (atomic_read(&cred->usage) != 0)
140                 panic("CRED: put_cred_rcu() sees %p with usage %d\n",
141                       cred, atomic_read(&cred->usage));
142 #endif
143
144         security_cred_free(cred);
145         key_put(cred->thread_keyring);
146         key_put(cred->request_key_auth);
147         release_tgcred(cred);
148         if (cred->group_info)
149                 put_group_info(cred->group_info);
150         free_uid(cred->user);
151         kmem_cache_free(cred_jar, cred);
152 }
153
154 /**
155  * __put_cred - Destroy a set of credentials
156  * @cred: The record to release
157  *
158  * Destroy a set of credentials on which no references remain.
159  */
160 void __put_cred(struct cred *cred)
161 {
162         kdebug("__put_cred(%p{%d,%d})", cred,
163                atomic_read(&cred->usage),
164                read_cred_subscribers(cred));
165
166         BUG_ON(atomic_read(&cred->usage) != 0);
167 #ifdef CONFIG_DEBUG_CREDENTIALS
168         BUG_ON(read_cred_subscribers(cred) != 0);
169         cred->magic = CRED_MAGIC_DEAD;
170         cred->put_addr = __builtin_return_address(0);
171 #endif
172         BUG_ON(cred == current->cred);
173         BUG_ON(cred == current->real_cred);
174
175         call_rcu(&cred->rcu, put_cred_rcu);
176 }
177 EXPORT_SYMBOL(__put_cred);
178
179 /*
180  * Clean up a task's credentials when it exits
181  */
182 void exit_creds(struct task_struct *tsk)
183 {
184         struct cred *cred;
185
186         kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
187                atomic_read(&tsk->cred->usage),
188                read_cred_subscribers(tsk->cred));
189
190         cred = (struct cred *) tsk->real_cred;
191         tsk->real_cred = NULL;
192         validate_creds(cred);
193         alter_cred_subscribers(cred, -1);
194         put_cred(cred);
195
196         cred = (struct cred *) tsk->cred;
197         tsk->cred = NULL;
198         validate_creds(cred);
199         alter_cred_subscribers(cred, -1);
200         put_cred(cred);
201
202         cred = (struct cred *) tsk->replacement_session_keyring;
203         if (cred) {
204                 tsk->replacement_session_keyring = NULL;
205                 validate_creds(cred);
206                 put_cred(cred);
207         }
208 }
209
210 /**
211  * get_task_cred - Get another task's objective credentials
212  * @task: The task to query
213  *
214  * Get the objective credentials of a task, pinning them so that they can't go
215  * away.  Accessing a task's credentials directly is not permitted.
216  *
217  * The caller must also make sure task doesn't get deleted, either by holding a
218  * ref on task or by holding tasklist_lock to prevent it from being unlinked.
219  */
220 const struct cred *get_task_cred(struct task_struct *task)
221 {
222         const struct cred *cred;
223
224         rcu_read_lock();
225
226         do {
227                 cred = __task_cred((task));
228                 BUG_ON(!cred);
229         } while (!atomic_inc_not_zero(&((struct cred *)cred)->usage));
230
231         rcu_read_unlock();
232         return cred;
233 }
234
235 /*
236  * Allocate blank credentials, such that the credentials can be filled in at a
237  * later date without risk of ENOMEM.
238  */
239 struct cred *cred_alloc_blank(void)
240 {
241         struct cred *new;
242
243         new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
244         if (!new)
245                 return NULL;
246
247 #ifdef CONFIG_KEYS
248         new->tgcred = kzalloc(sizeof(*new->tgcred), GFP_KERNEL);
249         if (!new->tgcred) {
250                 kmem_cache_free(cred_jar, new);
251                 return NULL;
252         }
253         atomic_set(&new->tgcred->usage, 1);
254 #endif
255
256         atomic_set(&new->usage, 1);
257 #ifdef CONFIG_DEBUG_CREDENTIALS
258         new->magic = CRED_MAGIC;
259 #endif
260
261         if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
262                 goto error;
263
264         return new;
265
266 error:
267         abort_creds(new);
268         return NULL;
269 }
270
271 /**
272  * prepare_creds - Prepare a new set of credentials for modification
273  *
274  * Prepare a new set of task credentials for modification.  A task's creds
275  * shouldn't generally be modified directly, therefore this function is used to
276  * prepare a new copy, which the caller then modifies and then commits by
277  * calling commit_creds().
278  *
279  * Preparation involves making a copy of the objective creds for modification.
280  *
281  * Returns a pointer to the new creds-to-be if successful, NULL otherwise.
282  *
283  * Call commit_creds() or abort_creds() to clean up.
284  */
285 struct cred *prepare_creds(void)
286 {
287         struct task_struct *task = current;
288         const struct cred *old;
289         struct cred *new;
290
291         validate_process_creds();
292
293         new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
294         if (!new)
295                 return NULL;
296
297         kdebug("prepare_creds() alloc %p", new);
298
299         old = task->cred;
300         memcpy(new, old, sizeof(struct cred));
301
302         atomic_set(&new->usage, 1);
303         set_cred_subscribers(new, 0);
304         get_group_info(new->group_info);
305         get_uid(new->user);
306
307 #ifdef CONFIG_KEYS
308         key_get(new->thread_keyring);
309         key_get(new->request_key_auth);
310         atomic_inc(&new->tgcred->usage);
311 #endif
312
313 #ifdef CONFIG_SECURITY
314         new->security = NULL;
315 #endif
316
317         if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
318                 goto error;
319         validate_creds(new);
320         return new;
321
322 error:
323         abort_creds(new);
324         return NULL;
325 }
326 EXPORT_SYMBOL(prepare_creds);
327
328 /*
329  * Prepare credentials for current to perform an execve()
330  * - The caller must hold ->cred_guard_mutex
331  */
332 struct cred *prepare_exec_creds(void)
333 {
334         struct thread_group_cred *tgcred = NULL;
335         struct cred *new;
336
337 #ifdef CONFIG_KEYS
338         tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
339         if (!tgcred)
340                 return NULL;
341 #endif
342
343         new = prepare_creds();
344         if (!new) {
345                 kfree(tgcred);
346                 return new;
347         }
348
349 #ifdef CONFIG_KEYS
350         /* newly exec'd tasks don't get a thread keyring */
351         key_put(new->thread_keyring);
352         new->thread_keyring = NULL;
353
354         /* create a new per-thread-group creds for all this set of threads to
355          * share */
356         memcpy(tgcred, new->tgcred, sizeof(struct thread_group_cred));
357
358         atomic_set(&tgcred->usage, 1);
359         spin_lock_init(&tgcred->lock);
360
361         /* inherit the session keyring; new process keyring */
362         key_get(tgcred->session_keyring);
363         tgcred->process_keyring = NULL;
364
365         release_tgcred(new);
366         new->tgcred = tgcred;
367 #endif
368
369         return new;
370 }
371
372 /*
373  * Copy credentials for the new process created by fork()
374  *
375  * We share if we can, but under some circumstances we have to generate a new
376  * set.
377  *
378  * The new process gets the current process's subjective credentials as its
379  * objective and subjective credentials
380  */
381 int copy_creds(struct task_struct *p, unsigned long clone_flags)
382 {
383 #ifdef CONFIG_KEYS
384         struct thread_group_cred *tgcred;
385 #endif
386         struct cred *new;
387         int ret;
388
389         p->replacement_session_keyring = NULL;
390
391         if (
392 #ifdef CONFIG_KEYS
393                 !p->cred->thread_keyring &&
394 #endif
395                 clone_flags & CLONE_THREAD
396             ) {
397                 p->real_cred = get_cred(p->cred);
398                 get_cred(p->cred);
399                 alter_cred_subscribers(p->cred, 2);
400                 kdebug("share_creds(%p{%d,%d})",
401                        p->cred, atomic_read(&p->cred->usage),
402                        read_cred_subscribers(p->cred));
403                 atomic_inc(&p->cred->user->processes);
404                 return 0;
405         }
406
407         new = prepare_creds();
408         if (!new)
409                 return -ENOMEM;
410
411         if (clone_flags & CLONE_NEWUSER) {
412                 ret = create_user_ns(new);
413                 if (ret < 0)
414                         goto error_put;
415         }
416
417         /* cache user_ns in cred.  Doesn't need a refcount because it will
418          * stay pinned by cred->user
419          */
420         new->user_ns = new->user->user_ns;
421
422 #ifdef CONFIG_KEYS
423         /* new threads get their own thread keyrings if their parent already
424          * had one */
425         if (new->thread_keyring) {
426                 key_put(new->thread_keyring);
427                 new->thread_keyring = NULL;
428                 if (clone_flags & CLONE_THREAD)
429                         install_thread_keyring_to_cred(new);
430         }
431
432         /* we share the process and session keyrings between all the threads in
433          * a process - this is slightly icky as we violate COW credentials a
434          * bit */
435         if (!(clone_flags & CLONE_THREAD)) {
436                 tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
437                 if (!tgcred) {
438                         ret = -ENOMEM;
439                         goto error_put;
440                 }
441                 atomic_set(&tgcred->usage, 1);
442                 spin_lock_init(&tgcred->lock);
443                 tgcred->process_keyring = NULL;
444                 tgcred->session_keyring = key_get(new->tgcred->session_keyring);
445
446                 release_tgcred(new);
447                 new->tgcred = tgcred;
448         }
449 #endif
450
451         atomic_inc(&new->user->processes);
452         p->cred = p->real_cred = get_cred(new);
453         alter_cred_subscribers(new, 2);
454         validate_creds(new);
455         return 0;
456
457 error_put:
458         put_cred(new);
459         return ret;
460 }
461
462 /**
463  * commit_creds - Install new credentials upon the current task
464  * @new: The credentials to be assigned
465  *
466  * Install a new set of credentials to the current task, using RCU to replace
467  * the old set.  Both the objective and the subjective credentials pointers are
468  * updated.  This function may not be called if the subjective credentials are
469  * in an overridden state.
470  *
471  * This function eats the caller's reference to the new credentials.
472  *
473  * Always returns 0 thus allowing this function to be tail-called at the end
474  * of, say, sys_setgid().
475  */
476 int commit_creds(struct cred *new)
477 {
478         struct task_struct *task = current;
479         const struct cred *old = task->real_cred;
480
481         kdebug("commit_creds(%p{%d,%d})", new,
482                atomic_read(&new->usage),
483                read_cred_subscribers(new));
484
485         BUG_ON(task->cred != old);
486 #ifdef CONFIG_DEBUG_CREDENTIALS
487         BUG_ON(read_cred_subscribers(old) < 2);
488         validate_creds(old);
489         validate_creds(new);
490 #endif
491         BUG_ON(atomic_read(&new->usage) < 1);
492
493         get_cred(new); /* we will require a ref for the subj creds too */
494
495         /* dumpability changes */
496         if (old->euid != new->euid ||
497             old->egid != new->egid ||
498             old->fsuid != new->fsuid ||
499             old->fsgid != new->fsgid ||
500             !cap_issubset(new->cap_permitted, old->cap_permitted)) {
501                 if (task->mm)
502                         set_dumpable(task->mm, suid_dumpable);
503                 task->pdeath_signal = 0;
504                 smp_wmb();
505         }
506
507         /* alter the thread keyring */
508         if (new->fsuid != old->fsuid)
509                 key_fsuid_changed(task);
510         if (new->fsgid != old->fsgid)
511                 key_fsgid_changed(task);
512
513         /* do it
514          * RLIMIT_NPROC limits on user->processes have already been checked
515          * in set_user().
516          */
517         alter_cred_subscribers(new, 2);
518         if (new->user != old->user)
519                 atomic_inc(&new->user->processes);
520         rcu_assign_pointer(task->real_cred, new);
521         rcu_assign_pointer(task->cred, new);
522         if (new->user != old->user)
523                 atomic_dec(&old->user->processes);
524         alter_cred_subscribers(old, -2);
525
526         /* send notifications */
527         if (new->uid   != old->uid  ||
528             new->euid  != old->euid ||
529             new->suid  != old->suid ||
530             new->fsuid != old->fsuid)
531                 proc_id_connector(task, PROC_EVENT_UID);
532
533         if (new->gid   != old->gid  ||
534             new->egid  != old->egid ||
535             new->sgid  != old->sgid ||
536             new->fsgid != old->fsgid)
537                 proc_id_connector(task, PROC_EVENT_GID);
538
539         /* release the old obj and subj refs both */
540         put_cred(old);
541         put_cred(old);
542         return 0;
543 }
544 EXPORT_SYMBOL(commit_creds);
545
546 /**
547  * abort_creds - Discard a set of credentials and unlock the current task
548  * @new: The credentials that were going to be applied
549  *
550  * Discard a set of credentials that were under construction and unlock the
551  * current task.
552  */
553 void abort_creds(struct cred *new)
554 {
555         kdebug("abort_creds(%p{%d,%d})", new,
556                atomic_read(&new->usage),
557                read_cred_subscribers(new));
558
559 #ifdef CONFIG_DEBUG_CREDENTIALS
560         BUG_ON(read_cred_subscribers(new) != 0);
561 #endif
562         BUG_ON(atomic_read(&new->usage) < 1);
563         put_cred(new);
564 }
565 EXPORT_SYMBOL(abort_creds);
566
567 /**
568  * override_creds - Override the current process's subjective credentials
569  * @new: The credentials to be assigned
570  *
571  * Install a set of temporary override subjective credentials on the current
572  * process, returning the old set for later reversion.
573  */
574 const struct cred *override_creds(const struct cred *new)
575 {
576         const struct cred *old = current->cred;
577
578         kdebug("override_creds(%p{%d,%d})", new,
579                atomic_read(&new->usage),
580                read_cred_subscribers(new));
581
582         validate_creds(old);
583         validate_creds(new);
584         get_cred(new);
585         alter_cred_subscribers(new, 1);
586         rcu_assign_pointer(current->cred, new);
587         alter_cred_subscribers(old, -1);
588
589         kdebug("override_creds() = %p{%d,%d}", old,
590                atomic_read(&old->usage),
591                read_cred_subscribers(old));
592         return old;
593 }
594 EXPORT_SYMBOL(override_creds);
595
596 /**
597  * revert_creds - Revert a temporary subjective credentials override
598  * @old: The credentials to be restored
599  *
600  * Revert a temporary set of override subjective credentials to an old set,
601  * discarding the override set.
602  */
603 void revert_creds(const struct cred *old)
604 {
605         const struct cred *override = current->cred;
606
607         kdebug("revert_creds(%p{%d,%d})", old,
608                atomic_read(&old->usage),
609                read_cred_subscribers(old));
610
611         validate_creds(old);
612         validate_creds(override);
613         alter_cred_subscribers(old, 1);
614         rcu_assign_pointer(current->cred, old);
615         alter_cred_subscribers(override, -1);
616         put_cred(override);
617 }
618 EXPORT_SYMBOL(revert_creds);
619
620 /*
621  * initialise the credentials stuff
622  */
623 void __init cred_init(void)
624 {
625         /* allocate a slab in which we can store credentials */
626         cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred),
627                                      0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
628 }
629
630 /**
631  * prepare_kernel_cred - Prepare a set of credentials for a kernel service
632  * @daemon: A userspace daemon to be used as a reference
633  *
634  * Prepare a set of credentials for a kernel service.  This can then be used to
635  * override a task's own credentials so that work can be done on behalf of that
636  * task that requires a different subjective context.
637  *
638  * @daemon is used to provide a base for the security record, but can be NULL.
639  * If @daemon is supplied, then the security data will be derived from that;
640  * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
641  *
642  * The caller may change these controls afterwards if desired.
643  *
644  * Returns the new credentials or NULL if out of memory.
645  *
646  * Does not take, and does not return holding current->cred_replace_mutex.
647  */
648 struct cred *prepare_kernel_cred(struct task_struct *daemon)
649 {
650 #ifdef CONFIG_KEYS
651         struct thread_group_cred *tgcred;
652 #endif
653         const struct cred *old;
654         struct cred *new;
655
656         new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
657         if (!new)
658                 return NULL;
659
660 #ifdef CONFIG_KEYS
661         tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
662         if (!tgcred) {
663                 kmem_cache_free(cred_jar, new);
664                 return NULL;
665         }
666 #endif
667
668         kdebug("prepare_kernel_cred() alloc %p", new);
669
670         if (daemon)
671                 old = get_task_cred(daemon);
672         else
673                 old = get_cred(&init_cred);
674
675         validate_creds(old);
676
677         *new = *old;
678         atomic_set(&new->usage, 1);
679         set_cred_subscribers(new, 0);
680         get_uid(new->user);
681         get_group_info(new->group_info);
682
683 #ifdef CONFIG_KEYS
684         atomic_set(&tgcred->usage, 1);
685         spin_lock_init(&tgcred->lock);
686         tgcred->process_keyring = NULL;
687         tgcred->session_keyring = NULL;
688         new->tgcred = tgcred;
689         new->request_key_auth = NULL;
690         new->thread_keyring = NULL;
691         new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
692 #endif
693
694 #ifdef CONFIG_SECURITY
695         new->security = NULL;
696 #endif
697         if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
698                 goto error;
699
700         put_cred(old);
701         validate_creds(new);
702         return new;
703
704 error:
705         put_cred(new);
706         put_cred(old);
707         return NULL;
708 }
709 EXPORT_SYMBOL(prepare_kernel_cred);
710
711 /**
712  * set_security_override - Set the security ID in a set of credentials
713  * @new: The credentials to alter
714  * @secid: The LSM security ID to set
715  *
716  * Set the LSM security ID in a set of credentials so that the subjective
717  * security is overridden when an alternative set of credentials is used.
718  */
719 int set_security_override(struct cred *new, u32 secid)
720 {
721         return security_kernel_act_as(new, secid);
722 }
723 EXPORT_SYMBOL(set_security_override);
724
725 /**
726  * set_security_override_from_ctx - Set the security ID in a set of credentials
727  * @new: The credentials to alter
728  * @secctx: The LSM security context to generate the security ID from.
729  *
730  * Set the LSM security ID in a set of credentials so that the subjective
731  * security is overridden when an alternative set of credentials is used.  The
732  * security ID is specified in string form as a security context to be
733  * interpreted by the LSM.
734  */
735 int set_security_override_from_ctx(struct cred *new, const char *secctx)
736 {
737         u32 secid;
738         int ret;
739
740         ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
741         if (ret < 0)
742                 return ret;
743
744         return set_security_override(new, secid);
745 }
746 EXPORT_SYMBOL(set_security_override_from_ctx);
747
748 /**
749  * set_create_files_as - Set the LSM file create context in a set of credentials
750  * @new: The credentials to alter
751  * @inode: The inode to take the context from
752  *
753  * Change the LSM file creation context in a set of credentials to be the same
754  * as the object context of the specified inode, so that the new inodes have
755  * the same MAC context as that inode.
756  */
757 int set_create_files_as(struct cred *new, struct inode *inode)
758 {
759         new->fsuid = inode->i_uid;
760         new->fsgid = inode->i_gid;
761         return security_kernel_create_files_as(new, inode);
762 }
763 EXPORT_SYMBOL(set_create_files_as);
764
765 #ifdef CONFIG_DEBUG_CREDENTIALS
766
767 bool creds_are_invalid(const struct cred *cred)
768 {
769         if (cred->magic != CRED_MAGIC)
770                 return true;
771 #ifdef CONFIG_SECURITY_SELINUX
772         /*
773          * cred->security == NULL if security_cred_alloc_blank() or
774          * security_prepare_creds() returned an error.
775          */
776         if (selinux_is_enabled() && cred->security) {
777                 if ((unsigned long) cred->security < PAGE_SIZE)
778                         return true;
779                 if ((*(u32 *)cred->security & 0xffffff00) ==
780                     (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
781                         return true;
782         }
783 #endif
784         return false;
785 }
786 EXPORT_SYMBOL(creds_are_invalid);
787
788 /*
789  * dump invalid credentials
790  */
791 static void dump_invalid_creds(const struct cred *cred, const char *label,
792                                const struct task_struct *tsk)
793 {
794         printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
795                label, cred,
796                cred == &init_cred ? "[init]" : "",
797                cred == tsk->real_cred ? "[real]" : "",
798                cred == tsk->cred ? "[eff]" : "");
799         printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
800                cred->magic, cred->put_addr);
801         printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
802                atomic_read(&cred->usage),
803                read_cred_subscribers(cred));
804         printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
805                cred->uid, cred->euid, cred->suid, cred->fsuid);
806         printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
807                cred->gid, cred->egid, cred->sgid, cred->fsgid);
808 #ifdef CONFIG_SECURITY
809         printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
810         if ((unsigned long) cred->security >= PAGE_SIZE &&
811             (((unsigned long) cred->security & 0xffffff00) !=
812              (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
813                 printk(KERN_ERR "CRED: ->security {%x, %x}\n",
814                        ((u32*)cred->security)[0],
815                        ((u32*)cred->security)[1]);
816 #endif
817 }
818
819 /*
820  * report use of invalid credentials
821  */
822 void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
823 {
824         printk(KERN_ERR "CRED: Invalid credentials\n");
825         printk(KERN_ERR "CRED: At %s:%u\n", file, line);
826         dump_invalid_creds(cred, "Specified", current);
827         BUG();
828 }
829 EXPORT_SYMBOL(__invalid_creds);
830
831 /*
832  * check the credentials on a process
833  */
834 void __validate_process_creds(struct task_struct *tsk,
835                               const char *file, unsigned line)
836 {
837         if (tsk->cred == tsk->real_cred) {
838                 if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
839                              creds_are_invalid(tsk->cred)))
840                         goto invalid_creds;
841         } else {
842                 if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
843                              read_cred_subscribers(tsk->cred) < 1 ||
844                              creds_are_invalid(tsk->real_cred) ||
845                              creds_are_invalid(tsk->cred)))
846                         goto invalid_creds;
847         }
848         return;
849
850 invalid_creds:
851         printk(KERN_ERR "CRED: Invalid process credentials\n");
852         printk(KERN_ERR "CRED: At %s:%u\n", file, line);
853
854         dump_invalid_creds(tsk->real_cred, "Real", tsk);
855         if (tsk->cred != tsk->real_cred)
856                 dump_invalid_creds(tsk->cred, "Effective", tsk);
857         else
858                 printk(KERN_ERR "CRED: Effective creds == Real creds\n");
859         BUG();
860 }
861 EXPORT_SYMBOL(__validate_process_creds);
862
863 /*
864  * check creds for do_exit()
865  */
866 void validate_creds_for_do_exit(struct task_struct *tsk)
867 {
868         kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
869                tsk->real_cred, tsk->cred,
870                atomic_read(&tsk->cred->usage),
871                read_cred_subscribers(tsk->cred));
872
873         __validate_process_creds(tsk, __FILE__, __LINE__);
874 }
875
876 #endif /* CONFIG_DEBUG_CREDENTIALS */