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