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

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