linux/kernel/cred.c
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   1/* Task credentials management - see Documentation/security/credentials.txt
   2 *
   3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public Licence
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the Licence, or (at your option) any later version.
  10 */
  11#include <linux/export.h>
  12#include <linux/cred.h>
  13#include <linux/slab.h>
  14#include <linux/sched.h>
  15#include <linux/key.h>
  16#include <linux/keyctl.h>
  17#include <linux/init_task.h>
  18#include <linux/security.h>
  19#include <linux/binfmts.h>
  20#include <linux/cn_proc.h>
  21
  22#if 0
  23#define kdebug(FMT, ...) \
  24        printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
  25#else
  26#define kdebug(FMT, ...) \
  27        no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
  28#endif
  29
  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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