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