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TOMOYO Linux Cross Reference
Linux/kernel/cred.c

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

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