CRED: Fix memory leak in error handling
[linux-2.6.git] / kernel / cred.c
1 /* Task credentials management - see Documentation/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/module.h>
12 #include <linux/cred.h>
13 #include <linux/sched.h>
14 #include <linux/key.h>
15 #include <linux/keyctl.h>
16 #include <linux/init_task.h>
17 #include <linux/security.h>
18 #include <linux/cn_proc.h>
19 #include "cred-internals.h"
20
21 #if 0
22 #define kdebug(FMT, ...) \
23         printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
24 #else
25 static inline __attribute__((format(printf, 1, 2)))
26 void no_printk(const char *fmt, ...)
27 {
28 }
29 #define kdebug(FMT, ...) \
30         no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
31 #endif
32
33 static struct kmem_cache *cred_jar;
34
35 /*
36  * The common credentials for the initial task's thread group
37  */
38 #ifdef CONFIG_KEYS
39 static struct thread_group_cred init_tgcred = {
40         .usage  = ATOMIC_INIT(2),
41         .tgid   = 0,
42         .lock   = SPIN_LOCK_UNLOCKED,
43 };
44 #endif
45
46 /*
47  * The initial credentials for the initial task
48  */
49 struct cred init_cred = {
50         .usage                  = ATOMIC_INIT(4),
51 #ifdef CONFIG_DEBUG_CREDENTIALS
52         .subscribers            = ATOMIC_INIT(2),
53         .magic                  = CRED_MAGIC,
54 #endif
55         .securebits             = SECUREBITS_DEFAULT,
56         .cap_inheritable        = CAP_INIT_INH_SET,
57         .cap_permitted          = CAP_FULL_SET,
58         .cap_effective          = CAP_INIT_EFF_SET,
59         .cap_bset               = CAP_INIT_BSET,
60         .user                   = INIT_USER,
61         .group_info             = &init_groups,
62 #ifdef CONFIG_KEYS
63         .tgcred                 = &init_tgcred,
64 #endif
65 };
66
67 static inline void set_cred_subscribers(struct cred *cred, int n)
68 {
69 #ifdef CONFIG_DEBUG_CREDENTIALS
70         atomic_set(&cred->subscribers, n);
71 #endif
72 }
73
74 static inline int read_cred_subscribers(const struct cred *cred)
75 {
76 #ifdef CONFIG_DEBUG_CREDENTIALS
77         return atomic_read(&cred->subscribers);
78 #else
79         return 0;
80 #endif
81 }
82
83 static inline void alter_cred_subscribers(const struct cred *_cred, int n)
84 {
85 #ifdef CONFIG_DEBUG_CREDENTIALS
86         struct cred *cred = (struct cred *) _cred;
87
88         atomic_add(n, &cred->subscribers);
89 #endif
90 }
91
92 /*
93  * Dispose of the shared task group credentials
94  */
95 #ifdef CONFIG_KEYS
96 static void release_tgcred_rcu(struct rcu_head *rcu)
97 {
98         struct thread_group_cred *tgcred =
99                 container_of(rcu, struct thread_group_cred, rcu);
100
101         BUG_ON(atomic_read(&tgcred->usage) != 0);
102
103         key_put(tgcred->session_keyring);
104         key_put(tgcred->process_keyring);
105         kfree(tgcred);
106 }
107 #endif
108
109 /*
110  * Release a set of thread group credentials.
111  */
112 static void release_tgcred(struct cred *cred)
113 {
114 #ifdef CONFIG_KEYS
115         struct thread_group_cred *tgcred = cred->tgcred;
116
117         if (atomic_dec_and_test(&tgcred->usage))
118                 call_rcu(&tgcred->rcu, release_tgcred_rcu);
119 #endif
120 }
121
122 /*
123  * The RCU callback to actually dispose of a set of credentials
124  */
125 static void put_cred_rcu(struct rcu_head *rcu)
126 {
127         struct cred *cred = container_of(rcu, struct cred, rcu);
128
129         kdebug("put_cred_rcu(%p)", cred);
130
131 #ifdef CONFIG_DEBUG_CREDENTIALS
132         if (cred->magic != CRED_MAGIC_DEAD ||
133             atomic_read(&cred->usage) != 0 ||
134             read_cred_subscribers(cred) != 0)
135                 panic("CRED: put_cred_rcu() sees %p with"
136                       " mag %x, put %p, usage %d, subscr %d\n",
137                       cred, cred->magic, cred->put_addr,
138                       atomic_read(&cred->usage),
139                       read_cred_subscribers(cred));
140 #else
141         if (atomic_read(&cred->usage) != 0)
142                 panic("CRED: put_cred_rcu() sees %p with usage %d\n",
143                       cred, atomic_read(&cred->usage));
144 #endif
145
146         security_cred_free(cred);
147         key_put(cred->thread_keyring);
148         key_put(cred->request_key_auth);
149         release_tgcred(cred);
150         if (cred->group_info)
151                 put_group_info(cred->group_info);
152         free_uid(cred->user);
153         kmem_cache_free(cred_jar, cred);
154 }
155
156 /**
157  * __put_cred - Destroy a set of credentials
158  * @cred: The record to release
159  *
160  * Destroy a set of credentials on which no references remain.
161  */
162 void __put_cred(struct cred *cred)
163 {
164         kdebug("__put_cred(%p{%d,%d})", cred,
165                atomic_read(&cred->usage),
166                read_cred_subscribers(cred));
167
168         BUG_ON(atomic_read(&cred->usage) != 0);
169 #ifdef CONFIG_DEBUG_CREDENTIALS
170         BUG_ON(read_cred_subscribers(cred) != 0);
171         cred->magic = CRED_MAGIC_DEAD;
172         cred->put_addr = __builtin_return_address(0);
173 #endif
174         BUG_ON(cred == current->cred);
175         BUG_ON(cred == current->real_cred);
176
177         call_rcu(&cred->rcu, put_cred_rcu);
178 }
179 EXPORT_SYMBOL(__put_cred);
180
181 /*
182  * Clean up a task's credentials when it exits
183  */
184 void exit_creds(struct task_struct *tsk)
185 {
186         struct cred *cred;
187
188         kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
189                atomic_read(&tsk->cred->usage),
190                read_cred_subscribers(tsk->cred));
191
192         cred = (struct cred *) tsk->real_cred;
193         tsk->real_cred = NULL;
194         validate_creds(cred);
195         alter_cred_subscribers(cred, -1);
196         put_cred(cred);
197
198         cred = (struct cred *) tsk->cred;
199         tsk->cred = NULL;
200         validate_creds(cred);
201         alter_cred_subscribers(cred, -1);
202         put_cred(cred);
203
204         cred = (struct cred *) tsk->replacement_session_keyring;
205         if (cred) {
206                 tsk->replacement_session_keyring = NULL;
207                 validate_creds(cred);
208                 put_cred(cred);
209         }
210 }
211
212 /*
213  * Allocate blank credentials, such that the credentials can be filled in at a
214  * later date without risk of ENOMEM.
215  */
216 struct cred *cred_alloc_blank(void)
217 {
218         struct cred *new;
219
220         new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
221         if (!new)
222                 return NULL;
223
224 #ifdef CONFIG_KEYS
225         new->tgcred = kzalloc(sizeof(*new->tgcred), GFP_KERNEL);
226         if (!new->tgcred) {
227                 kmem_cache_free(cred_jar, new);
228                 return NULL;
229         }
230         atomic_set(&new->tgcred->usage, 1);
231 #endif
232
233         atomic_set(&new->usage, 1);
234
235         if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
236                 goto error;
237
238 #ifdef CONFIG_DEBUG_CREDENTIALS
239         new->magic = CRED_MAGIC;
240 #endif
241         return new;
242
243 error:
244         abort_creds(new);
245         return NULL;
246 }
247
248 /**
249  * prepare_creds - Prepare a new set of credentials for modification
250  *
251  * Prepare a new set of task credentials for modification.  A task's creds
252  * shouldn't generally be modified directly, therefore this function is used to
253  * prepare a new copy, which the caller then modifies and then commits by
254  * calling commit_creds().
255  *
256  * Preparation involves making a copy of the objective creds for modification.
257  *
258  * Returns a pointer to the new creds-to-be if successful, NULL otherwise.
259  *
260  * Call commit_creds() or abort_creds() to clean up.
261  */
262 struct cred *prepare_creds(void)
263 {
264         struct task_struct *task = current;
265         const struct cred *old;
266         struct cred *new;
267
268         validate_process_creds();
269
270         new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
271         if (!new)
272                 return NULL;
273
274         kdebug("prepare_creds() alloc %p", new);
275
276         old = task->cred;
277         memcpy(new, old, sizeof(struct cred));
278
279         atomic_set(&new->usage, 1);
280         set_cred_subscribers(new, 0);
281         get_group_info(new->group_info);
282         get_uid(new->user);
283
284 #ifdef CONFIG_KEYS
285         key_get(new->thread_keyring);
286         key_get(new->request_key_auth);
287         atomic_inc(&new->tgcred->usage);
288 #endif
289
290 #ifdef CONFIG_SECURITY
291         new->security = NULL;
292 #endif
293
294         if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
295                 goto error;
296         validate_creds(new);
297         return new;
298
299 error:
300         abort_creds(new);
301         return NULL;
302 }
303 EXPORT_SYMBOL(prepare_creds);
304
305 /*
306  * Prepare credentials for current to perform an execve()
307  * - The caller must hold current->cred_guard_mutex
308  */
309 struct cred *prepare_exec_creds(void)
310 {
311         struct thread_group_cred *tgcred = NULL;
312         struct cred *new;
313
314 #ifdef CONFIG_KEYS
315         tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
316         if (!tgcred)
317                 return NULL;
318 #endif
319
320         new = prepare_creds();
321         if (!new) {
322                 kfree(tgcred);
323                 return new;
324         }
325
326 #ifdef CONFIG_KEYS
327         /* newly exec'd tasks don't get a thread keyring */
328         key_put(new->thread_keyring);
329         new->thread_keyring = NULL;
330
331         /* create a new per-thread-group creds for all this set of threads to
332          * share */
333         memcpy(tgcred, new->tgcred, sizeof(struct thread_group_cred));
334
335         atomic_set(&tgcred->usage, 1);
336         spin_lock_init(&tgcred->lock);
337
338         /* inherit the session keyring; new process keyring */
339         key_get(tgcred->session_keyring);
340         tgcred->process_keyring = NULL;
341
342         release_tgcred(new);
343         new->tgcred = tgcred;
344 #endif
345
346         return new;
347 }
348
349 /*
350  * prepare new credentials for the usermode helper dispatcher
351  */
352 struct cred *prepare_usermodehelper_creds(void)
353 {
354 #ifdef CONFIG_KEYS
355         struct thread_group_cred *tgcred = NULL;
356 #endif
357         struct cred *new;
358
359 #ifdef CONFIG_KEYS
360         tgcred = kzalloc(sizeof(*new->tgcred), GFP_ATOMIC);
361         if (!tgcred)
362                 return NULL;
363 #endif
364
365         new = kmem_cache_alloc(cred_jar, GFP_ATOMIC);
366         if (!new)
367                 goto free_tgcred;
368
369         kdebug("prepare_usermodehelper_creds() alloc %p", new);
370
371         memcpy(new, &init_cred, sizeof(struct cred));
372
373         atomic_set(&new->usage, 1);
374         set_cred_subscribers(new, 0);
375         get_group_info(new->group_info);
376         get_uid(new->user);
377
378 #ifdef CONFIG_KEYS
379         new->thread_keyring = NULL;
380         new->request_key_auth = NULL;
381         new->jit_keyring = KEY_REQKEY_DEFL_DEFAULT;
382
383         atomic_set(&tgcred->usage, 1);
384         spin_lock_init(&tgcred->lock);
385         new->tgcred = tgcred;
386 #endif
387
388 #ifdef CONFIG_SECURITY
389         new->security = NULL;
390 #endif
391         if (security_prepare_creds(new, &init_cred, GFP_ATOMIC) < 0)
392                 goto error;
393         validate_creds(new);
394
395         BUG_ON(atomic_read(&new->usage) != 1);
396         return new;
397
398 error:
399         put_cred(new);
400 free_tgcred:
401 #ifdef CONFIG_KEYS
402         kfree(tgcred);
403 #endif
404         return NULL;
405 }
406
407 /*
408  * Copy credentials for the new process created by fork()
409  *
410  * We share if we can, but under some circumstances we have to generate a new
411  * set.
412  *
413  * The new process gets the current process's subjective credentials as its
414  * objective and subjective credentials
415  */
416 int copy_creds(struct task_struct *p, unsigned long clone_flags)
417 {
418 #ifdef CONFIG_KEYS
419         struct thread_group_cred *tgcred;
420 #endif
421         struct cred *new;
422         int ret;
423
424         mutex_init(&p->cred_guard_mutex);
425
426         if (
427 #ifdef CONFIG_KEYS
428                 !p->cred->thread_keyring &&
429 #endif
430                 clone_flags & CLONE_THREAD
431             ) {
432                 p->real_cred = get_cred(p->cred);
433                 get_cred(p->cred);
434                 alter_cred_subscribers(p->cred, 2);
435                 kdebug("share_creds(%p{%d,%d})",
436                        p->cred, atomic_read(&p->cred->usage),
437                        read_cred_subscribers(p->cred));
438                 atomic_inc(&p->cred->user->processes);
439                 return 0;
440         }
441
442         new = prepare_creds();
443         if (!new)
444                 return -ENOMEM;
445
446         if (clone_flags & CLONE_NEWUSER) {
447                 ret = create_user_ns(new);
448                 if (ret < 0)
449                         goto error_put;
450         }
451
452 #ifdef CONFIG_KEYS
453         /* new threads get their own thread keyrings if their parent already
454          * had one */
455         if (new->thread_keyring) {
456                 key_put(new->thread_keyring);
457                 new->thread_keyring = NULL;
458                 if (clone_flags & CLONE_THREAD)
459                         install_thread_keyring_to_cred(new);
460         }
461
462         /* we share the process and session keyrings between all the threads in
463          * a process - this is slightly icky as we violate COW credentials a
464          * bit */
465         if (!(clone_flags & CLONE_THREAD)) {
466                 tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
467                 if (!tgcred) {
468                         ret = -ENOMEM;
469                         goto error_put;
470                 }
471                 atomic_set(&tgcred->usage, 1);
472                 spin_lock_init(&tgcred->lock);
473                 tgcred->process_keyring = NULL;
474                 tgcred->session_keyring = key_get(new->tgcred->session_keyring);
475
476                 release_tgcred(new);
477                 new->tgcred = tgcred;
478         }
479 #endif
480
481         atomic_inc(&new->user->processes);
482         p->cred = p->real_cred = get_cred(new);
483         alter_cred_subscribers(new, 2);
484         validate_creds(new);
485         return 0;
486
487 error_put:
488         put_cred(new);
489         return ret;
490 }
491
492 /**
493  * commit_creds - Install new credentials upon the current task
494  * @new: The credentials to be assigned
495  *
496  * Install a new set of credentials to the current task, using RCU to replace
497  * the old set.  Both the objective and the subjective credentials pointers are
498  * updated.  This function may not be called if the subjective credentials are
499  * in an overridden state.
500  *
501  * This function eats the caller's reference to the new credentials.
502  *
503  * Always returns 0 thus allowing this function to be tail-called at the end
504  * of, say, sys_setgid().
505  */
506 int commit_creds(struct cred *new)
507 {
508         struct task_struct *task = current;
509         const struct cred *old = task->real_cred;
510
511         kdebug("commit_creds(%p{%d,%d})", new,
512                atomic_read(&new->usage),
513                read_cred_subscribers(new));
514
515         BUG_ON(task->cred != old);
516 #ifdef CONFIG_DEBUG_CREDENTIALS
517         BUG_ON(read_cred_subscribers(old) < 2);
518         validate_creds(old);
519         validate_creds(new);
520 #endif
521         BUG_ON(atomic_read(&new->usage) < 1);
522
523         security_commit_creds(new, old);
524
525         get_cred(new); /* we will require a ref for the subj creds too */
526
527         /* dumpability changes */
528         if (old->euid != new->euid ||
529             old->egid != new->egid ||
530             old->fsuid != new->fsuid ||
531             old->fsgid != new->fsgid ||
532             !cap_issubset(new->cap_permitted, old->cap_permitted)) {
533                 if (task->mm)
534                         set_dumpable(task->mm, suid_dumpable);
535                 task->pdeath_signal = 0;
536                 smp_wmb();
537         }
538
539         /* alter the thread keyring */
540         if (new->fsuid != old->fsuid)
541                 key_fsuid_changed(task);
542         if (new->fsgid != old->fsgid)
543                 key_fsgid_changed(task);
544
545         /* do it
546          * - What if a process setreuid()'s and this brings the
547          *   new uid over his NPROC rlimit?  We can check this now
548          *   cheaply with the new uid cache, so if it matters
549          *   we should be checking for it.  -DaveM
550          */
551         alter_cred_subscribers(new, 2);
552         if (new->user != old->user)
553                 atomic_inc(&new->user->processes);
554         rcu_assign_pointer(task->real_cred, new);
555         rcu_assign_pointer(task->cred, new);
556         if (new->user != old->user)
557                 atomic_dec(&old->user->processes);
558         alter_cred_subscribers(old, -2);
559
560         sched_switch_user(task);
561
562         /* send notifications */
563         if (new->uid   != old->uid  ||
564             new->euid  != old->euid ||
565             new->suid  != old->suid ||
566             new->fsuid != old->fsuid)
567                 proc_id_connector(task, PROC_EVENT_UID);
568
569         if (new->gid   != old->gid  ||
570             new->egid  != old->egid ||
571             new->sgid  != old->sgid ||
572             new->fsgid != old->fsgid)
573                 proc_id_connector(task, PROC_EVENT_GID);
574
575         /* release the old obj and subj refs both */
576         put_cred(old);
577         put_cred(old);
578         return 0;
579 }
580 EXPORT_SYMBOL(commit_creds);
581
582 /**
583  * abort_creds - Discard a set of credentials and unlock the current task
584  * @new: The credentials that were going to be applied
585  *
586  * Discard a set of credentials that were under construction and unlock the
587  * current task.
588  */
589 void abort_creds(struct cred *new)
590 {
591         kdebug("abort_creds(%p{%d,%d})", new,
592                atomic_read(&new->usage),
593                read_cred_subscribers(new));
594
595 #ifdef CONFIG_DEBUG_CREDENTIALS
596         BUG_ON(read_cred_subscribers(new) != 0);
597 #endif
598         BUG_ON(atomic_read(&new->usage) < 1);
599         put_cred(new);
600 }
601 EXPORT_SYMBOL(abort_creds);
602
603 /**
604  * override_creds - Override the current process's subjective credentials
605  * @new: The credentials to be assigned
606  *
607  * Install a set of temporary override subjective credentials on the current
608  * process, returning the old set for later reversion.
609  */
610 const struct cred *override_creds(const struct cred *new)
611 {
612         const struct cred *old = current->cred;
613
614         kdebug("override_creds(%p{%d,%d})", new,
615                atomic_read(&new->usage),
616                read_cred_subscribers(new));
617
618         validate_creds(old);
619         validate_creds(new);
620         get_cred(new);
621         alter_cred_subscribers(new, 1);
622         rcu_assign_pointer(current->cred, new);
623         alter_cred_subscribers(old, -1);
624
625         kdebug("override_creds() = %p{%d,%d}", old,
626                atomic_read(&old->usage),
627                read_cred_subscribers(old));
628         return old;
629 }
630 EXPORT_SYMBOL(override_creds);
631
632 /**
633  * revert_creds - Revert a temporary subjective credentials override
634  * @old: The credentials to be restored
635  *
636  * Revert a temporary set of override subjective credentials to an old set,
637  * discarding the override set.
638  */
639 void revert_creds(const struct cred *old)
640 {
641         const struct cred *override = current->cred;
642
643         kdebug("revert_creds(%p{%d,%d})", old,
644                atomic_read(&old->usage),
645                read_cred_subscribers(old));
646
647         validate_creds(old);
648         validate_creds(override);
649         alter_cred_subscribers(old, 1);
650         rcu_assign_pointer(current->cred, old);
651         alter_cred_subscribers(override, -1);
652         put_cred(override);
653 }
654 EXPORT_SYMBOL(revert_creds);
655
656 /*
657  * initialise the credentials stuff
658  */
659 void __init cred_init(void)
660 {
661         /* allocate a slab in which we can store credentials */
662         cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred),
663                                      0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
664 }
665
666 /**
667  * prepare_kernel_cred - Prepare a set of credentials for a kernel service
668  * @daemon: A userspace daemon to be used as a reference
669  *
670  * Prepare a set of credentials for a kernel service.  This can then be used to
671  * override a task's own credentials so that work can be done on behalf of that
672  * task that requires a different subjective context.
673  *
674  * @daemon is used to provide a base for the security record, but can be NULL.
675  * If @daemon is supplied, then the security data will be derived from that;
676  * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
677  *
678  * The caller may change these controls afterwards if desired.
679  *
680  * Returns the new credentials or NULL if out of memory.
681  *
682  * Does not take, and does not return holding current->cred_replace_mutex.
683  */
684 struct cred *prepare_kernel_cred(struct task_struct *daemon)
685 {
686         const struct cred *old;
687         struct cred *new;
688
689         new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
690         if (!new)
691                 return NULL;
692
693         kdebug("prepare_kernel_cred() alloc %p", new);
694
695         if (daemon)
696                 old = get_task_cred(daemon);
697         else
698                 old = get_cred(&init_cred);
699
700         validate_creds(old);
701
702         *new = *old;
703         get_uid(new->user);
704         get_group_info(new->group_info);
705
706 #ifdef CONFIG_KEYS
707         atomic_inc(&init_tgcred.usage);
708         new->tgcred = &init_tgcred;
709         new->request_key_auth = NULL;
710         new->thread_keyring = NULL;
711         new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
712 #endif
713
714 #ifdef CONFIG_SECURITY
715         new->security = NULL;
716 #endif
717         if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
718                 goto error;
719
720         atomic_set(&new->usage, 1);
721         set_cred_subscribers(new, 0);
722         put_cred(old);
723         validate_creds(new);
724         return new;
725
726 error:
727         put_cred(new);
728         put_cred(old);
729         return NULL;
730 }
731 EXPORT_SYMBOL(prepare_kernel_cred);
732
733 /**
734  * set_security_override - Set the security ID in a set of credentials
735  * @new: The credentials to alter
736  * @secid: The LSM security ID to set
737  *
738  * Set the LSM security ID in a set of credentials so that the subjective
739  * security is overridden when an alternative set of credentials is used.
740  */
741 int set_security_override(struct cred *new, u32 secid)
742 {
743         return security_kernel_act_as(new, secid);
744 }
745 EXPORT_SYMBOL(set_security_override);
746
747 /**
748  * set_security_override_from_ctx - Set the security ID in a set of credentials
749  * @new: The credentials to alter
750  * @secctx: The LSM security context to generate the security ID from.
751  *
752  * Set the LSM security ID in a set of credentials so that the subjective
753  * security is overridden when an alternative set of credentials is used.  The
754  * security ID is specified in string form as a security context to be
755  * interpreted by the LSM.
756  */
757 int set_security_override_from_ctx(struct cred *new, const char *secctx)
758 {
759         u32 secid;
760         int ret;
761
762         ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
763         if (ret < 0)
764                 return ret;
765
766         return set_security_override(new, secid);
767 }
768 EXPORT_SYMBOL(set_security_override_from_ctx);
769
770 /**
771  * set_create_files_as - Set the LSM file create context in a set of credentials
772  * @new: The credentials to alter
773  * @inode: The inode to take the context from
774  *
775  * Change the LSM file creation context in a set of credentials to be the same
776  * as the object context of the specified inode, so that the new inodes have
777  * the same MAC context as that inode.
778  */
779 int set_create_files_as(struct cred *new, struct inode *inode)
780 {
781         new->fsuid = inode->i_uid;
782         new->fsgid = inode->i_gid;
783         return security_kernel_create_files_as(new, inode);
784 }
785 EXPORT_SYMBOL(set_create_files_as);
786
787 #ifdef CONFIG_DEBUG_CREDENTIALS
788
789 bool creds_are_invalid(const struct cred *cred)
790 {
791         if (cred->magic != CRED_MAGIC)
792                 return true;
793         if (atomic_read(&cred->usage) < atomic_read(&cred->subscribers))
794                 return true;
795 #ifdef CONFIG_SECURITY_SELINUX
796         if (selinux_is_enabled()) {
797                 if ((unsigned long) cred->security < PAGE_SIZE)
798                         return true;
799                 if ((*(u32 *)cred->security & 0xffffff00) ==
800                     (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
801                         return true;
802         }
803 #endif
804         return false;
805 }
806 EXPORT_SYMBOL(creds_are_invalid);
807
808 /*
809  * dump invalid credentials
810  */
811 static void dump_invalid_creds(const struct cred *cred, const char *label,
812                                const struct task_struct *tsk)
813 {
814         printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
815                label, cred,
816                cred == &init_cred ? "[init]" : "",
817                cred == tsk->real_cred ? "[real]" : "",
818                cred == tsk->cred ? "[eff]" : "");
819         printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
820                cred->magic, cred->put_addr);
821         printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
822                atomic_read(&cred->usage),
823                read_cred_subscribers(cred));
824         printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
825                cred->uid, cred->euid, cred->suid, cred->fsuid);
826         printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
827                cred->gid, cred->egid, cred->sgid, cred->fsgid);
828 #ifdef CONFIG_SECURITY
829         printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
830         if ((unsigned long) cred->security >= PAGE_SIZE &&
831             (((unsigned long) cred->security & 0xffffff00) !=
832              (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
833                 printk(KERN_ERR "CRED: ->security {%x, %x}\n",
834                        ((u32*)cred->security)[0],
835                        ((u32*)cred->security)[1]);
836 #endif
837 }
838
839 /*
840  * report use of invalid credentials
841  */
842 void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
843 {
844         printk(KERN_ERR "CRED: Invalid credentials\n");
845         printk(KERN_ERR "CRED: At %s:%u\n", file, line);
846         dump_invalid_creds(cred, "Specified", current);
847         BUG();
848 }
849 EXPORT_SYMBOL(__invalid_creds);
850
851 /*
852  * check the credentials on a process
853  */
854 void __validate_process_creds(struct task_struct *tsk,
855                               const char *file, unsigned line)
856 {
857         if (tsk->cred == tsk->real_cred) {
858                 if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
859                              creds_are_invalid(tsk->cred)))
860                         goto invalid_creds;
861         } else {
862                 if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
863                              read_cred_subscribers(tsk->cred) < 1 ||
864                              creds_are_invalid(tsk->real_cred) ||
865                              creds_are_invalid(tsk->cred)))
866                         goto invalid_creds;
867         }
868         return;
869
870 invalid_creds:
871         printk(KERN_ERR "CRED: Invalid process credentials\n");
872         printk(KERN_ERR "CRED: At %s:%u\n", file, line);
873
874         dump_invalid_creds(tsk->real_cred, "Real", tsk);
875         if (tsk->cred != tsk->real_cred)
876                 dump_invalid_creds(tsk->cred, "Effective", tsk);
877         else
878                 printk(KERN_ERR "CRED: Effective creds == Real creds\n");
879         BUG();
880 }
881 EXPORT_SYMBOL(__validate_process_creds);
882
883 /*
884  * check creds for do_exit()
885  */
886 void validate_creds_for_do_exit(struct task_struct *tsk)
887 {
888         kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
889                tsk->real_cred, tsk->cred,
890                atomic_read(&tsk->cred->usage),
891                read_cred_subscribers(tsk->cred));
892
893         __validate_process_creds(tsk, __FILE__, __LINE__);
894 }
895
896 #endif /* CONFIG_DEBUG_CREDENTIALS */