Root/kernel/cred.c

1/* Task credentials management - see Documentation/security/credentials.txt
2 *
3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11#include <linux/module.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/cn_proc.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#define kdebug(FMT, ...) \
26    no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
27#endif
28
29static struct kmem_cache *cred_jar;
30
31/*
32 * The common credentials for the initial task's thread group
33 */
34#ifdef CONFIG_KEYS
35static struct thread_group_cred init_tgcred = {
36    .usage = ATOMIC_INIT(2),
37    .tgid = 0,
38    .lock = __SPIN_LOCK_UNLOCKED(init_cred.tgcred.lock),
39};
40#endif
41
42/*
43 * The initial credentials for the initial task
44 */
45struct cred init_cred = {
46    .usage = ATOMIC_INIT(4),
47#ifdef CONFIG_DEBUG_CREDENTIALS
48    .subscribers = ATOMIC_INIT(2),
49    .magic = CRED_MAGIC,
50#endif
51    .securebits = SECUREBITS_DEFAULT,
52    .cap_inheritable = CAP_EMPTY_SET,
53    .cap_permitted = CAP_FULL_SET,
54    .cap_effective = CAP_FULL_SET,
55    .cap_bset = CAP_FULL_SET,
56    .user = INIT_USER,
57    .user_ns = &init_user_ns,
58    .group_info = &init_groups,
59#ifdef CONFIG_KEYS
60    .tgcred = &init_tgcred,
61#endif
62};
63
64static inline void set_cred_subscribers(struct cred *cred, int n)
65{
66#ifdef CONFIG_DEBUG_CREDENTIALS
67    atomic_set(&cred->subscribers, n);
68#endif
69}
70
71static inline int read_cred_subscribers(const struct cred *cred)
72{
73#ifdef CONFIG_DEBUG_CREDENTIALS
74    return atomic_read(&cred->subscribers);
75#else
76    return 0;
77#endif
78}
79
80static inline void alter_cred_subscribers(const struct cred *_cred, int n)
81{
82#ifdef CONFIG_DEBUG_CREDENTIALS
83    struct cred *cred = (struct cred *) _cred;
84
85    atomic_add(n, &cred->subscribers);
86#endif
87}
88
89/*
90 * Dispose of the shared task group credentials
91 */
92#ifdef CONFIG_KEYS
93static void release_tgcred_rcu(struct rcu_head *rcu)
94{
95    struct thread_group_cred *tgcred =
96        container_of(rcu, struct thread_group_cred, rcu);
97
98    BUG_ON(atomic_read(&tgcred->usage) != 0);
99
100    key_put(tgcred->session_keyring);
101    key_put(tgcred->process_keyring);
102    kfree(tgcred);
103}
104#endif
105
106/*
107 * Release a set of thread group credentials.
108 */
109static void release_tgcred(struct cred *cred)
110{
111#ifdef CONFIG_KEYS
112    struct thread_group_cred *tgcred = cred->tgcred;
113
114    if (atomic_dec_and_test(&tgcred->usage))
115        call_rcu(&tgcred->rcu, release_tgcred_rcu);
116#endif
117}
118
119/*
120 * The RCU callback to actually dispose of a set of credentials
121 */
122static void put_cred_rcu(struct rcu_head *rcu)
123{
124    struct cred *cred = container_of(rcu, struct cred, rcu);
125
126    kdebug("put_cred_rcu(%p)", cred);
127
128#ifdef CONFIG_DEBUG_CREDENTIALS
129    if (cred->magic != CRED_MAGIC_DEAD ||
130        atomic_read(&cred->usage) != 0 ||
131        read_cred_subscribers(cred) != 0)
132        panic("CRED: put_cred_rcu() sees %p with"
133              " mag %x, put %p, usage %d, subscr %d\n",
134              cred, cred->magic, cred->put_addr,
135              atomic_read(&cred->usage),
136              read_cred_subscribers(cred));
137#else
138    if (atomic_read(&cred->usage) != 0)
139        panic("CRED: put_cred_rcu() sees %p with usage %d\n",
140              cred, atomic_read(&cred->usage));
141#endif
142
143    security_cred_free(cred);
144    key_put(cred->thread_keyring);
145    key_put(cred->request_key_auth);
146    release_tgcred(cred);
147    if (cred->group_info)
148        put_group_info(cred->group_info);
149    free_uid(cred->user);
150    kmem_cache_free(cred_jar, cred);
151}
152
153/**
154 * __put_cred - Destroy a set of credentials
155 * @cred: The record to release
156 *
157 * Destroy a set of credentials on which no references remain.
158 */
159void __put_cred(struct cred *cred)
160{
161    kdebug("__put_cred(%p{%d,%d})", cred,
162           atomic_read(&cred->usage),
163           read_cred_subscribers(cred));
164
165    BUG_ON(atomic_read(&cred->usage) != 0);
166#ifdef CONFIG_DEBUG_CREDENTIALS
167    BUG_ON(read_cred_subscribers(cred) != 0);
168    cred->magic = CRED_MAGIC_DEAD;
169    cred->put_addr = __builtin_return_address(0);
170#endif
171    BUG_ON(cred == current->cred);
172    BUG_ON(cred == current->real_cred);
173
174    call_rcu(&cred->rcu, put_cred_rcu);
175}
176EXPORT_SYMBOL(__put_cred);
177
178/*
179 * Clean up a task's credentials when it exits
180 */
181void exit_creds(struct task_struct *tsk)
182{
183    struct cred *cred;
184
185    kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
186           atomic_read(&tsk->cred->usage),
187           read_cred_subscribers(tsk->cred));
188
189    cred = (struct cred *) tsk->real_cred;
190    tsk->real_cred = NULL;
191    validate_creds(cred);
192    alter_cred_subscribers(cred, -1);
193    put_cred(cred);
194
195    cred = (struct cred *) tsk->cred;
196    tsk->cred = NULL;
197    validate_creds(cred);
198    alter_cred_subscribers(cred, -1);
199    put_cred(cred);
200
201    cred = (struct cred *) tsk->replacement_session_keyring;
202    if (cred) {
203        tsk->replacement_session_keyring = NULL;
204        validate_creds(cred);
205        put_cred(cred);
206    }
207}
208
209/**
210 * get_task_cred - Get another task's objective credentials
211 * @task: The task to query
212 *
213 * Get the objective credentials of a task, pinning them so that they can't go
214 * away. Accessing a task's credentials directly is not permitted.
215 *
216 * The caller must also make sure task doesn't get deleted, either by holding a
217 * ref on task or by holding tasklist_lock to prevent it from being unlinked.
218 */
219const struct cred *get_task_cred(struct task_struct *task)
220{
221    const struct cred *cred;
222
223    rcu_read_lock();
224
225    do {
226        cred = __task_cred((task));
227        BUG_ON(!cred);
228    } while (!atomic_inc_not_zero(&((struct cred *)cred)->usage));
229
230    rcu_read_unlock();
231    return cred;
232}
233
234/*
235 * Allocate blank credentials, such that the credentials can be filled in at a
236 * later date without risk of ENOMEM.
237 */
238struct cred *cred_alloc_blank(void)
239{
240    struct cred *new;
241
242    new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
243    if (!new)
244        return NULL;
245
246#ifdef CONFIG_KEYS
247    new->tgcred = kzalloc(sizeof(*new->tgcred), GFP_KERNEL);
248    if (!new->tgcred) {
249        kmem_cache_free(cred_jar, new);
250        return NULL;
251    }
252    atomic_set(&new->tgcred->usage, 1);
253#endif
254
255    atomic_set(&new->usage, 1);
256#ifdef CONFIG_DEBUG_CREDENTIALS
257    new->magic = CRED_MAGIC;
258#endif
259
260    if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
261        goto error;
262
263    return new;
264
265error:
266    abort_creds(new);
267    return NULL;
268}
269
270/**
271 * prepare_creds - Prepare a new set of credentials for modification
272 *
273 * Prepare a new set of task credentials for modification. A task's creds
274 * shouldn't generally be modified directly, therefore this function is used to
275 * prepare a new copy, which the caller then modifies and then commits by
276 * calling commit_creds().
277 *
278 * Preparation involves making a copy of the objective creds for modification.
279 *
280 * Returns a pointer to the new creds-to-be if successful, NULL otherwise.
281 *
282 * Call commit_creds() or abort_creds() to clean up.
283 */
284struct cred *prepare_creds(void)
285{
286    struct task_struct *task = current;
287    const struct cred *old;
288    struct cred *new;
289
290    validate_process_creds();
291
292    new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
293    if (!new)
294        return NULL;
295
296    kdebug("prepare_creds() alloc %p", new);
297
298    old = task->cred;
299    memcpy(new, old, sizeof(struct cred));
300
301    atomic_set(&new->usage, 1);
302    set_cred_subscribers(new, 0);
303    get_group_info(new->group_info);
304    get_uid(new->user);
305
306#ifdef CONFIG_KEYS
307    key_get(new->thread_keyring);
308    key_get(new->request_key_auth);
309    atomic_inc(&new->tgcred->usage);
310#endif
311
312#ifdef CONFIG_SECURITY
313    new->security = NULL;
314#endif
315
316    if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
317        goto error;
318    validate_creds(new);
319    return new;
320
321error:
322    abort_creds(new);
323    return NULL;
324}
325EXPORT_SYMBOL(prepare_creds);
326
327/*
328 * Prepare credentials for current to perform an execve()
329 * - The caller must hold ->cred_guard_mutex
330 */
331struct cred *prepare_exec_creds(void)
332{
333    struct thread_group_cred *tgcred = NULL;
334    struct cred *new;
335
336#ifdef CONFIG_KEYS
337    tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
338    if (!tgcred)
339        return NULL;
340#endif
341
342    new = prepare_creds();
343    if (!new) {
344        kfree(tgcred);
345        return new;
346    }
347
348#ifdef CONFIG_KEYS
349    /* newly exec'd tasks don't get a thread keyring */
350    key_put(new->thread_keyring);
351    new->thread_keyring = NULL;
352
353    /* create a new per-thread-group creds for all this set of threads to
354     * share */
355    memcpy(tgcred, new->tgcred, sizeof(struct thread_group_cred));
356
357    atomic_set(&tgcred->usage, 1);
358    spin_lock_init(&tgcred->lock);
359
360    /* inherit the session keyring; new process keyring */
361    key_get(tgcred->session_keyring);
362    tgcred->process_keyring = NULL;
363
364    release_tgcred(new);
365    new->tgcred = tgcred;
366#endif
367
368    return new;
369}
370
371/*
372 * Copy credentials for the new process created by fork()
373 *
374 * We share if we can, but under some circumstances we have to generate a new
375 * set.
376 *
377 * The new process gets the current process's subjective credentials as its
378 * objective and subjective credentials
379 */
380int copy_creds(struct task_struct *p, unsigned long clone_flags)
381{
382#ifdef CONFIG_KEYS
383    struct thread_group_cred *tgcred;
384#endif
385    struct cred *new;
386    int ret;
387
388    if (
389#ifdef CONFIG_KEYS
390        !p->cred->thread_keyring &&
391#endif
392        clone_flags & CLONE_THREAD
393        ) {
394        p->real_cred = get_cred(p->cred);
395        get_cred(p->cred);
396        alter_cred_subscribers(p->cred, 2);
397        kdebug("share_creds(%p{%d,%d})",
398               p->cred, atomic_read(&p->cred->usage),
399               read_cred_subscribers(p->cred));
400        atomic_inc(&p->cred->user->processes);
401        return 0;
402    }
403
404    new = prepare_creds();
405    if (!new)
406        return -ENOMEM;
407
408    if (clone_flags & CLONE_NEWUSER) {
409        ret = create_user_ns(new);
410        if (ret < 0)
411            goto error_put;
412    }
413
414    /* cache user_ns in cred. Doesn't need a refcount because it will
415     * stay pinned by cred->user
416     */
417    new->user_ns = new->user->user_ns;
418
419#ifdef CONFIG_KEYS
420    /* new threads get their own thread keyrings if their parent already
421     * had one */
422    if (new->thread_keyring) {
423        key_put(new->thread_keyring);
424        new->thread_keyring = NULL;
425        if (clone_flags & CLONE_THREAD)
426            install_thread_keyring_to_cred(new);
427    }
428
429    /* we share the process and session keyrings between all the threads in
430     * a process - this is slightly icky as we violate COW credentials a
431     * bit */
432    if (!(clone_flags & CLONE_THREAD)) {
433        tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
434        if (!tgcred) {
435            ret = -ENOMEM;
436            goto error_put;
437        }
438        atomic_set(&tgcred->usage, 1);
439        spin_lock_init(&tgcred->lock);
440        tgcred->process_keyring = NULL;
441        tgcred->session_keyring = key_get(new->tgcred->session_keyring);
442
443        release_tgcred(new);
444        new->tgcred = tgcred;
445    }
446#endif
447
448    atomic_inc(&new->user->processes);
449    p->cred = p->real_cred = get_cred(new);
450    alter_cred_subscribers(new, 2);
451    validate_creds(new);
452    return 0;
453
454error_put:
455    put_cred(new);
456    return ret;
457}
458
459/**
460 * commit_creds - Install new credentials upon the current task
461 * @new: The credentials to be assigned
462 *
463 * Install a new set of credentials to the current task, using RCU to replace
464 * the old set. Both the objective and the subjective credentials pointers are
465 * updated. This function may not be called if the subjective credentials are
466 * in an overridden state.
467 *
468 * This function eats the caller's reference to the new credentials.
469 *
470 * Always returns 0 thus allowing this function to be tail-called at the end
471 * of, say, sys_setgid().
472 */
473int commit_creds(struct cred *new)
474{
475    struct task_struct *task = current;
476    const struct cred *old = task->real_cred;
477
478    kdebug("commit_creds(%p{%d,%d})", new,
479           atomic_read(&new->usage),
480           read_cred_subscribers(new));
481
482    BUG_ON(task->cred != old);
483#ifdef CONFIG_DEBUG_CREDENTIALS
484    BUG_ON(read_cred_subscribers(old) < 2);
485    validate_creds(old);
486    validate_creds(new);
487#endif
488    BUG_ON(atomic_read(&new->usage) < 1);
489
490    get_cred(new); /* we will require a ref for the subj creds too */
491
492    /* dumpability changes */
493    if (old->euid != new->euid ||
494        old->egid != new->egid ||
495        old->fsuid != new->fsuid ||
496        old->fsgid != new->fsgid ||
497        !cap_issubset(new->cap_permitted, old->cap_permitted)) {
498        if (task->mm)
499            set_dumpable(task->mm, suid_dumpable);
500        task->pdeath_signal = 0;
501        smp_wmb();
502    }
503
504    /* alter the thread keyring */
505    if (new->fsuid != old->fsuid)
506        key_fsuid_changed(task);
507    if (new->fsgid != old->fsgid)
508        key_fsgid_changed(task);
509
510    /* do it
511     * - What if a process setreuid()'s and this brings the
512     * new uid over his NPROC rlimit? We can check this now
513     * cheaply with the new uid cache, so if it matters
514     * we should be checking for it. -DaveM
515     */
516    alter_cred_subscribers(new, 2);
517    if (new->user != old->user)
518        atomic_inc(&new->user->processes);
519    rcu_assign_pointer(task->real_cred, new);
520    rcu_assign_pointer(task->cred, new);
521    if (new->user != old->user)
522        atomic_dec(&old->user->processes);
523    alter_cred_subscribers(old, -2);
524
525    /* send notifications */
526    if (new->uid != old->uid ||
527        new->euid != old->euid ||
528        new->suid != old->suid ||
529        new->fsuid != old->fsuid)
530        proc_id_connector(task, PROC_EVENT_UID);
531
532    if (new->gid != old->gid ||
533        new->egid != old->egid ||
534        new->sgid != old->sgid ||
535        new->fsgid != old->fsgid)
536        proc_id_connector(task, PROC_EVENT_GID);
537
538    /* release the old obj and subj refs both */
539    put_cred(old);
540    put_cred(old);
541    return 0;
542}
543EXPORT_SYMBOL(commit_creds);
544
545/**
546 * abort_creds - Discard a set of credentials and unlock the current task
547 * @new: The credentials that were going to be applied
548 *
549 * Discard a set of credentials that were under construction and unlock the
550 * current task.
551 */
552void abort_creds(struct cred *new)
553{
554    kdebug("abort_creds(%p{%d,%d})", new,
555           atomic_read(&new->usage),
556           read_cred_subscribers(new));
557
558#ifdef CONFIG_DEBUG_CREDENTIALS
559    BUG_ON(read_cred_subscribers(new) != 0);
560#endif
561    BUG_ON(atomic_read(&new->usage) < 1);
562    put_cred(new);
563}
564EXPORT_SYMBOL(abort_creds);
565
566/**
567 * override_creds - Override the current process's subjective credentials
568 * @new: The credentials to be assigned
569 *
570 * Install a set of temporary override subjective credentials on the current
571 * process, returning the old set for later reversion.
572 */
573const struct cred *override_creds(const struct cred *new)
574{
575    const struct cred *old = current->cred;
576
577    kdebug("override_creds(%p{%d,%d})", new,
578           atomic_read(&new->usage),
579           read_cred_subscribers(new));
580
581    validate_creds(old);
582    validate_creds(new);
583    get_cred(new);
584    alter_cred_subscribers(new, 1);
585    rcu_assign_pointer(current->cred, new);
586    alter_cred_subscribers(old, -1);
587
588    kdebug("override_creds() = %p{%d,%d}", old,
589           atomic_read(&old->usage),
590           read_cred_subscribers(old));
591    return old;
592}
593EXPORT_SYMBOL(override_creds);
594
595/**
596 * revert_creds - Revert a temporary subjective credentials override
597 * @old: The credentials to be restored
598 *
599 * Revert a temporary set of override subjective credentials to an old set,
600 * discarding the override set.
601 */
602void revert_creds(const struct cred *old)
603{
604    const struct cred *override = current->cred;
605
606    kdebug("revert_creds(%p{%d,%d})", old,
607           atomic_read(&old->usage),
608           read_cred_subscribers(old));
609
610    validate_creds(old);
611    validate_creds(override);
612    alter_cred_subscribers(old, 1);
613    rcu_assign_pointer(current->cred, old);
614    alter_cred_subscribers(override, -1);
615    put_cred(override);
616}
617EXPORT_SYMBOL(revert_creds);
618
619/*
620 * initialise the credentials stuff
621 */
622void __init cred_init(void)
623{
624    /* allocate a slab in which we can store credentials */
625    cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred),
626                     0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
627}
628
629/**
630 * prepare_kernel_cred - Prepare a set of credentials for a kernel service
631 * @daemon: A userspace daemon to be used as a reference
632 *
633 * Prepare a set of credentials for a kernel service. This can then be used to
634 * override a task's own credentials so that work can be done on behalf of that
635 * task that requires a different subjective context.
636 *
637 * @daemon is used to provide a base for the security record, but can be NULL.
638 * If @daemon is supplied, then the security data will be derived from that;
639 * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
640 *
641 * The caller may change these controls afterwards if desired.
642 *
643 * Returns the new credentials or NULL if out of memory.
644 *
645 * Does not take, and does not return holding current->cred_replace_mutex.
646 */
647struct cred *prepare_kernel_cred(struct task_struct *daemon)
648{
649    const struct cred *old;
650    struct cred *new;
651
652    new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
653    if (!new)
654        return NULL;
655
656    kdebug("prepare_kernel_cred() alloc %p", new);
657
658    if (daemon)
659        old = get_task_cred(daemon);
660    else
661        old = get_cred(&init_cred);
662
663    validate_creds(old);
664
665    *new = *old;
666    atomic_set(&new->usage, 1);
667    set_cred_subscribers(new, 0);
668    get_uid(new->user);
669    get_group_info(new->group_info);
670
671#ifdef CONFIG_KEYS
672    atomic_inc(&init_tgcred.usage);
673    new->tgcred = &init_tgcred;
674    new->request_key_auth = NULL;
675    new->thread_keyring = NULL;
676    new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
677#endif
678
679#ifdef CONFIG_SECURITY
680    new->security = NULL;
681#endif
682    if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
683        goto error;
684
685    put_cred(old);
686    validate_creds(new);
687    return new;
688
689error:
690    put_cred(new);
691    put_cred(old);
692    return NULL;
693}
694EXPORT_SYMBOL(prepare_kernel_cred);
695
696/**
697 * set_security_override - Set the security ID in a set of credentials
698 * @new: The credentials to alter
699 * @secid: The LSM security ID to set
700 *
701 * Set the LSM security ID in a set of credentials so that the subjective
702 * security is overridden when an alternative set of credentials is used.
703 */
704int set_security_override(struct cred *new, u32 secid)
705{
706    return security_kernel_act_as(new, secid);
707}
708EXPORT_SYMBOL(set_security_override);
709
710/**
711 * set_security_override_from_ctx - Set the security ID in a set of credentials
712 * @new: The credentials to alter
713 * @secctx: The LSM security context to generate the security ID from.
714 *
715 * Set the LSM security ID in a set of credentials so that the subjective
716 * security is overridden when an alternative set of credentials is used. The
717 * security ID is specified in string form as a security context to be
718 * interpreted by the LSM.
719 */
720int set_security_override_from_ctx(struct cred *new, const char *secctx)
721{
722    u32 secid;
723    int ret;
724
725    ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
726    if (ret < 0)
727        return ret;
728
729    return set_security_override(new, secid);
730}
731EXPORT_SYMBOL(set_security_override_from_ctx);
732
733/**
734 * set_create_files_as - Set the LSM file create context in a set of credentials
735 * @new: The credentials to alter
736 * @inode: The inode to take the context from
737 *
738 * Change the LSM file creation context in a set of credentials to be the same
739 * as the object context of the specified inode, so that the new inodes have
740 * the same MAC context as that inode.
741 */
742int set_create_files_as(struct cred *new, struct inode *inode)
743{
744    new->fsuid = inode->i_uid;
745    new->fsgid = inode->i_gid;
746    return security_kernel_create_files_as(new, inode);
747}
748EXPORT_SYMBOL(set_create_files_as);
749
750#ifdef CONFIG_DEBUG_CREDENTIALS
751
752bool creds_are_invalid(const struct cred *cred)
753{
754    if (cred->magic != CRED_MAGIC)
755        return true;
756#ifdef CONFIG_SECURITY_SELINUX
757    /*
758     * cred->security == NULL if security_cred_alloc_blank() or
759     * security_prepare_creds() returned an error.
760     */
761    if (selinux_is_enabled() && cred->security) {
762        if ((unsigned long) cred->security < PAGE_SIZE)
763            return true;
764        if ((*(u32 *)cred->security & 0xffffff00) ==
765            (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
766            return true;
767    }
768#endif
769    return false;
770}
771EXPORT_SYMBOL(creds_are_invalid);
772
773/*
774 * dump invalid credentials
775 */
776static void dump_invalid_creds(const struct cred *cred, const char *label,
777                   const struct task_struct *tsk)
778{
779    printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
780           label, cred,
781           cred == &init_cred ? "[init]" : "",
782           cred == tsk->real_cred ? "[real]" : "",
783           cred == tsk->cred ? "[eff]" : "");
784    printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
785           cred->magic, cred->put_addr);
786    printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
787           atomic_read(&cred->usage),
788           read_cred_subscribers(cred));
789    printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
790           cred->uid, cred->euid, cred->suid, cred->fsuid);
791    printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
792           cred->gid, cred->egid, cred->sgid, cred->fsgid);
793#ifdef CONFIG_SECURITY
794    printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
795    if ((unsigned long) cred->security >= PAGE_SIZE &&
796        (((unsigned long) cred->security & 0xffffff00) !=
797         (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
798        printk(KERN_ERR "CRED: ->security {%x, %x}\n",
799               ((u32*)cred->security)[0],
800               ((u32*)cred->security)[1]);
801#endif
802}
803
804/*
805 * report use of invalid credentials
806 */
807void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
808{
809    printk(KERN_ERR "CRED: Invalid credentials\n");
810    printk(KERN_ERR "CRED: At %s:%u\n", file, line);
811    dump_invalid_creds(cred, "Specified", current);
812    BUG();
813}
814EXPORT_SYMBOL(__invalid_creds);
815
816/*
817 * check the credentials on a process
818 */
819void __validate_process_creds(struct task_struct *tsk,
820                  const char *file, unsigned line)
821{
822    if (tsk->cred == tsk->real_cred) {
823        if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
824                 creds_are_invalid(tsk->cred)))
825            goto invalid_creds;
826    } else {
827        if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
828                 read_cred_subscribers(tsk->cred) < 1 ||
829                 creds_are_invalid(tsk->real_cred) ||
830                 creds_are_invalid(tsk->cred)))
831            goto invalid_creds;
832    }
833    return;
834
835invalid_creds:
836    printk(KERN_ERR "CRED: Invalid process credentials\n");
837    printk(KERN_ERR "CRED: At %s:%u\n", file, line);
838
839    dump_invalid_creds(tsk->real_cred, "Real", tsk);
840    if (tsk->cred != tsk->real_cred)
841        dump_invalid_creds(tsk->cred, "Effective", tsk);
842    else
843        printk(KERN_ERR "CRED: Effective creds == Real creds\n");
844    BUG();
845}
846EXPORT_SYMBOL(__validate_process_creds);
847
848/*
849 * check creds for do_exit()
850 */
851void validate_creds_for_do_exit(struct task_struct *tsk)
852{
853    kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
854           tsk->real_cred, tsk->cred,
855           atomic_read(&tsk->cred->usage),
856           read_cred_subscribers(tsk->cred));
857
858    __validate_process_creds(tsk, __FILE__, __LINE__);
859}
860
861#endif /* CONFIG_DEBUG_CREDENTIALS */
862

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