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
  30 static struct kmem_cache *cred_jar;
  31
  32 /*
  33  * The initial credentials for the initial task
  34  */
  35 struct 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
  59 static 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
  66 static 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
  75 static 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  */
  87 static 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  */
 126 void __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 }
 143 EXPORT_SYMBOL(__put_cred);
 144
 145 /*
 146  * Clean up a task's credentials when it exits
 147  */
 148 void 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  */
 179 const 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  */
 198 struct 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
 216 error:
 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  */
 235 struct 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
 274 error:
 275         abort_creds(new);
 276         return NULL;
 277 }
 278 EXPORT_SYMBOL(prepare_creds);
 279
 280 /*
 281  * Prepare credentials for current to perform an execve()
 282  * - The caller must hold ->cred_guard_mutex
 283  */
 284 struct 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  */
 314 int 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
 370 error_put:
 371         put_cred(new);
 372         return ret;
 373 }
 374
 375 /**
 376  * commit_creds - Install new credentials upon the current task
 377  * @new: The credentials to be assigned
 378  *
 379  * Install a new set of credentials to the current task, using RCU to replace
 380  * the old set.  Both the objective and the subjective credentials pointers are
 381  * updated.  This function may not be called if the subjective credentials are
 382  * in an overridden state.
 383  *
 384  * This function eats the caller's reference to the new credentials.
 385  *
 386  * Always returns 0 thus allowing this function to be tail-called at the end
 387  * of, say, sys_setgid().
 388  */
 389 int commit_creds(struct cred *new)
 390 {
 391         struct task_struct *task = current;
 392         const struct cred *old = task->real_cred;
 393
 394         kdebug("commit_creds(%p{%d,%d})", new,
 395                atomic_read(&new->usage),
 396                read_cred_subscribers(new));
 397
 398         BUG_ON(task->cred != old);
 399 #ifdef CONFIG_DEBUG_CREDENTIALS
 400         BUG_ON(read_cred_subscribers(old) < 2);
 401         validate_creds(old);
 402         validate_creds(new);
 403 #endif
 404         BUG_ON(atomic_read(&new->usage) < 1);
 405
 406         get_cred(new); /* we will require a ref for the subj creds too */
 407
 408         /* dumpability changes */
 409         if (!uid_eq(old->euid, new->euid) ||
 410             !gid_eq(old->egid, new->egid) ||
 411             !uid_eq(old->fsuid, new->fsuid) ||
 412             !gid_eq(old->fsgid, new->fsgid) ||
 413             !cap_issubset(new->cap_permitted, old->cap_permitted)) {
 414                 if (task->mm)
 415                         set_dumpable(task->mm, suid_dumpable);
 416                 task->pdeath_signal = 0;
 417                 smp_wmb();
 418         }
 419
 420         /* alter the thread keyring */
 421         if (!uid_eq(new->fsuid, old->fsuid))
 422                 key_fsuid_changed(task);
 423         if (!gid_eq(new->fsgid, old->fsgid))
 424                 key_fsgid_changed(task);
 425
 426         /* do it
 427          * RLIMIT_NPROC limits on user->processes have already been checked
 428          * in set_user().
 429          */
 430         alter_cred_subscribers(new, 2);
 431         if (new->user != old->user)
 432                 atomic_inc(&new->user->processes);
 433         rcu_assign_pointer(task->real_cred, new);
 434         rcu_assign_pointer(task->cred, new);
 435         if (new->user != old->user)
 436                 atomic_dec(&old->user->processes);
 437         alter_cred_subscribers(old, -2);
 438
 439         /* send notifications */
 440         if (!uid_eq(new->uid,   old->uid)  ||
 441             !uid_eq(new->euid,  old->euid) ||
 442             !uid_eq(new->suid,  old->suid) ||
 443             !uid_eq(new->fsuid, old->fsuid))
 444                 proc_id_connector(task, PROC_EVENT_UID);
 445
 446         if (!gid_eq(new->gid,   old->gid)  ||
 447             !gid_eq(new->egid,  old->egid) ||
 448             !gid_eq(new->sgid,  old->sgid) ||
 449             !gid_eq(new->fsgid, old->fsgid))
 450                 proc_id_connector(task, PROC_EVENT_GID);
 451
 452         /* release the old obj and subj refs both */
 453         put_cred(old);
 454         put_cred(old);
 455         return 0;
 456 }
 457 EXPORT_SYMBOL(commit_creds);
 458
 459 /**
 460  * abort_creds - Discard a set of credentials and unlock the current task
 461  * @new: The credentials that were going to be applied
 462  *
 463  * Discard a set of credentials that were under construction and unlock the
 464  * current task.
 465  */
 466 void abort_creds(struct cred *new)
 467 {
 468         kdebug("abort_creds(%p{%d,%d})", new,
 469                atomic_read(&new->usage),
 470                read_cred_subscribers(new));
 471
 472 #ifdef CONFIG_DEBUG_CREDENTIALS
 473         BUG_ON(read_cred_subscribers(new) != 0);
 474 #endif
 475         BUG_ON(atomic_read(&new->usage) < 1);
 476         put_cred(new);
 477 }
 478 EXPORT_SYMBOL(abort_creds);
 479
 480 /**
 481  * override_creds - Override the current process's subjective credentials
 482  * @new: The credentials to be assigned
 483  *
 484  * Install a set of temporary override subjective credentials on the current
 485  * process, returning the old set for later reversion.
 486  */
 487 const struct cred *override_creds(const struct cred *new)
 488 {
 489         const struct cred *old = current->cred;
 490
 491         kdebug("override_creds(%p{%d,%d})", new,
 492                atomic_read(&new->usage),
 493                read_cred_subscribers(new));
 494
 495         validate_creds(old);
 496         validate_creds(new);
 497         get_cred(new);
 498         alter_cred_subscribers(new, 1);
 499         rcu_assign_pointer(current->cred, new);
 500         alter_cred_subscribers(old, -1);
 501
 502         kdebug("override_creds() = %p{%d,%d}", old,
 503                atomic_read(&old->usage),
 504                read_cred_subscribers(old));
 505         return old;
 506 }
 507 EXPORT_SYMBOL(override_creds);
 508
 509 /**
 510  * revert_creds - Revert a temporary subjective credentials override
 511  * @old: The credentials to be restored
 512  *
 513  * Revert a temporary set of override subjective credentials to an old set,
 514  * discarding the override set.
 515  */
 516 void revert_creds(const struct cred *old)
 517 {
 518         const struct cred *override = current->cred;
 519
 520         kdebug("revert_creds(%p{%d,%d})", old,
 521                atomic_read(&old->usage),
 522                read_cred_subscribers(old));
 523
 524         validate_creds(old);
 525         validate_creds(override);
 526         alter_cred_subscribers(old, 1);
 527         rcu_assign_pointer(current->cred, old);
 528         alter_cred_subscribers(override, -1);
 529         put_cred(override);
 530 }
 531 EXPORT_SYMBOL(revert_creds);
 532
 533 /*
 534  * initialise the credentials stuff
 535  */
 536 void __init cred_init(void)
 537 {
 538         /* allocate a slab in which we can store credentials */
 539         cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred),
 540                                      0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
 541 }
 542
 543 /**
 544  * prepare_kernel_cred - Prepare a set of credentials for a kernel service
 545  * @daemon: A userspace daemon to be used as a reference
 546  *
 547  * Prepare a set of credentials for a kernel service.  This can then be used to
 548  * override a task's own credentials so that work can be done on behalf of that
 549  * task that requires a different subjective context.
 550  *
 551  * @daemon is used to provide a base for the security record, but can be NULL.
 552  * If @daemon is supplied, then the security data will be derived from that;
 553  * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
 554  *
 555  * The caller may change these controls afterwards if desired.
 556  *
 557  * Returns the new credentials or NULL if out of memory.
 558  *
 559  * Does not take, and does not return holding current->cred_replace_mutex.
 560  */
 561 struct cred *prepare_kernel_cred(struct task_struct *daemon)
 562 {
 563         const struct cred *old;
 564         struct cred *new;
 565
 566         new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
 567         if (!new)
 568                 return NULL;
 569
 570         kdebug("prepare_kernel_cred() alloc %p", new);
 571
 572         if (daemon)
 573                 old = get_task_cred(daemon);
 574         else
 575                 old = get_cred(&init_cred);
 576
 577         validate_creds(old);
 578
 579         *new = *old;
 580         atomic_set(&new->usage, 1);
 581         set_cred_subscribers(new, 0);
 582         get_uid(new->user);
 583         get_user_ns(new->user_ns);
 584         get_group_info(new->group_info);
 585
 586 #ifdef CONFIG_KEYS
 587         new->session_keyring = NULL;
 588         new->process_keyring = NULL;
 589         new->thread_keyring = NULL;
 590         new->request_key_auth = NULL;
 591         new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
 592 #endif
 593
 594 #ifdef CONFIG_SECURITY
 595         new->security = NULL;
 596 #endif
 597         if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
 598                 goto error;
 599
 600         put_cred(old);
 601         validate_creds(new);
 602         return new;
 603
 604 error:
 605         put_cred(new);
 606         put_cred(old);
 607         return NULL;
 608 }
 609 EXPORT_SYMBOL(prepare_kernel_cred);
 610
 611 /**
 612  * set_security_override - Set the security ID in a set of credentials
 613  * @new: The credentials to alter
 614  * @secid: The LSM security ID to set
 615  *
 616  * Set the LSM security ID in a set of credentials so that the subjective
 617  * security is overridden when an alternative set of credentials is used.
 618  */
 619 int set_security_override(struct cred *new, u32 secid)
 620 {
 621         return security_kernel_act_as(new, secid);
 622 }
 623 EXPORT_SYMBOL(set_security_override);
 624
 625 /**
 626  * set_security_override_from_ctx - Set the security ID in a set of credentials
 627  * @new: The credentials to alter
 628  * @secctx: The LSM security context to generate the security ID from.
 629  *
 630  * Set the LSM security ID in a set of credentials so that the subjective
 631  * security is overridden when an alternative set of credentials is used.  The
 632  * security ID is specified in string form as a security context to be
 633  * interpreted by the LSM.
 634  */
 635 int set_security_override_from_ctx(struct cred *new, const char *secctx)
 636 {
 637         u32 secid;
 638         int ret;
 639
 640         ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
 641         if (ret < 0)
 642                 return ret;
 643
 644         return set_security_override(new, secid);
 645 }
 646 EXPORT_SYMBOL(set_security_override_from_ctx);
 647
 648 /**
 649  * set_create_files_as - Set the LSM file create context in a set of credentials
 650  * @new: The credentials to alter
 651  * @inode: The inode to take the context from
 652  *
 653  * Change the LSM file creation context in a set of credentials to be the same
 654  * as the object context of the specified inode, so that the new inodes have
 655  * the same MAC context as that inode.
 656  */
 657 int set_create_files_as(struct cred *new, struct inode *inode)
 658 {
 659         new->fsuid = inode->i_uid;
 660         new->fsgid = inode->i_gid;
 661         return security_kernel_create_files_as(new, inode);
 662 }
 663 EXPORT_SYMBOL(set_create_files_as);
 664
 665 #ifdef CONFIG_DEBUG_CREDENTIALS
 666
 667 bool creds_are_invalid(const struct cred *cred)
 668 {
 669         if (cred->magic != CRED_MAGIC)
 670                 return true;
 671 #ifdef CONFIG_SECURITY_SELINUX
 672         /*
 673          * cred->security == NULL if security_cred_alloc_blank() or
 674          * security_prepare_creds() returned an error.
 675          */
 676         if (selinux_is_enabled() && cred->security) {
 677                 if ((unsigned long) cred->security < PAGE_SIZE)
 678                         return true;
 679                 if ((*(u32 *)cred->security & 0xffffff00) ==
 680                     (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
 681                         return true;
 682         }
 683 #endif
 684         return false;
 685 }
 686 EXPORT_SYMBOL(creds_are_invalid);
 687
 688 /*
 689  * dump invalid credentials
 690  */
 691 static void dump_invalid_creds(const struct cred *cred, const char *label,
 692                                const struct task_struct *tsk)
 693 {
 694         printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
 695                label, cred,
 696                cred == &init_cred ? "[init]" : "",
 697                cred == tsk->real_cred ? "[real]" : "",
 698                cred == tsk->cred ? "[eff]" : "");
 699         printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
 700                cred->magic, cred->put_addr);
 701         printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
 702                atomic_read(&cred->usage),
 703                read_cred_subscribers(cred));
 704         printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
 705                 from_kuid_munged(&init_user_ns, cred->uid),
 706                 from_kuid_munged(&init_user_ns, cred->euid),
 707                 from_kuid_munged(&init_user_ns, cred->suid),
 708                 from_kuid_munged(&init_user_ns, cred->fsuid));
 709         printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
 710                 from_kgid_munged(&init_user_ns, cred->gid),
 711                 from_kgid_munged(&init_user_ns, cred->egid),
 712                 from_kgid_munged(&init_user_ns, cred->sgid),
 713                 from_kgid_munged(&init_user_ns, cred->fsgid));
 714 #ifdef CONFIG_SECURITY
 715         printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
 716         if ((unsigned long) cred->security >= PAGE_SIZE &&
 717             (((unsigned long) cred->security & 0xffffff00) !=
 718              (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
 719                 printk(KERN_ERR "CRED: ->security {%x, %x}\n",
 720                        ((u32*)cred->security)[0],
 721                        ((u32*)cred->security)[1]);
 722 #endif
 723 }
 724
 725 /*
 726  * report use of invalid credentials
 727  */
 728 void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
 729 {
 730         printk(KERN_ERR "CRED: Invalid credentials\n");
 731         printk(KERN_ERR "CRED: At %s:%u\n", file, line);
 732         dump_invalid_creds(cred, "Specified", current);
 733         BUG();
 734 }
 735 EXPORT_SYMBOL(__invalid_creds);
 736
 737 /*
 738  * check the credentials on a process
 739  */
 740 void __validate_process_creds(struct task_struct *tsk,
 741                               const char *file, unsigned line)
 742 {
 743         if (tsk->cred == tsk->real_cred) {
 744                 if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
 745                              creds_are_invalid(tsk->cred)))
 746                         goto invalid_creds;
 747         } else {
 748                 if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
 749                              read_cred_subscribers(tsk->cred) < 1 ||
 750                              creds_are_invalid(tsk->real_cred) ||
 751                              creds_are_invalid(tsk->cred)))
 752                         goto invalid_creds;
 753         }
 754         return;
 755
 756 invalid_creds:
 757         printk(KERN_ERR "CRED: Invalid process credentials\n");
 758         printk(KERN_ERR "CRED: At %s:%u\n", file, line);
 759
 760         dump_invalid_creds(tsk->real_cred, "Real", tsk);
 761         if (tsk->cred != tsk->real_cred)
 762                 dump_invalid_creds(tsk->cred, "Effective", tsk);
 763         else
 764                 printk(KERN_ERR "CRED: Effective creds == Real creds\n");
 765         BUG();
 766 }
 767 EXPORT_SYMBOL(__validate_process_creds);
 768
 769 /*
 770  * check creds for do_exit()
 771  */
 772 void validate_creds_for_do_exit(struct task_struct *tsk)
 773 {
 774         kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
 775                tsk->real_cred, tsk->cred,
 776                atomic_read(&tsk->cred->usage),
 777                read_cred_subscribers(tsk->cred));
 778
 779         __validate_process_creds(tsk, __FILE__, __LINE__);
 780 }
 781
 782 #endif /* CONFIG_DEBUG_CREDENTIALS */