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 common credentials for the initial task's thread group 34 */ 35 #ifdef CONFIG_KEYS 36 static struct thread_group_cred init_tgcred = { 37 .usage = ATOMIC_INIT(2), 38 .tgid = 0, 39 .lock = __SPIN_LOCK_UNLOCKED(init_cred.tgcred.lock), 40 }; 41 #endif 42 43 /* 44 * The initial credentials for the initial task 45 */ 46 struct cred init_cred = { 47 .usage = ATOMIC_INIT(4), 48 #ifdef CONFIG_DEBUG_CREDENTIALS 49 .subscribers = ATOMIC_INIT(2), 50 .magic = CRED_MAGIC, 51 #endif 52 .securebits = SECUREBITS_DEFAULT, 53 .cap_inheritable = CAP_EMPTY_SET, 54 .cap_permitted = CAP_FULL_SET, 55 .cap_effective = CAP_FULL_SET, 56 .cap_bset = CAP_FULL_SET, 57 .user = INIT_USER, 58 .user_ns = &init_user_ns, 59 .group_info = &init_groups, 60 #ifdef CONFIG_KEYS 61 .tgcred = &init_tgcred, 62 #endif 63 }; 64 65 static inline void set_cred_subscribers(struct cred *cred, int n) 66 { 67 #ifdef CONFIG_DEBUG_CREDENTIALS 68 atomic_set(&cred->subscribers, n); 69 #endif 70 } 71 72 static inline int read_cred_subscribers(const struct cred *cred) 73 { 74 #ifdef CONFIG_DEBUG_CREDENTIALS 75 return atomic_read(&cred->subscribers); 76 #else 77 return 0; 78 #endif 79 } 80 81 static inline void alter_cred_subscribers(const struct cred *_cred, int n) 82 { 83 #ifdef CONFIG_DEBUG_CREDENTIALS 84 struct cred *cred = (struct cred *) _cred; 85 86 atomic_add(n, &cred->subscribers); 87 #endif 88 } 89 90 /* 91 * Dispose of the shared task group credentials 92 */ 93 #ifdef CONFIG_KEYS 94 static void release_tgcred_rcu(struct rcu_head *rcu) 95 { 96 struct thread_group_cred *tgcred = 97 container_of(rcu, struct thread_group_cred, rcu); 98 99 BUG_ON(atomic_read(&tgcred->usage) != 0); 100 101 key_put(tgcred->session_keyring); 102 key_put(tgcred->process_keyring); 103 kfree(tgcred); 104 } 105 #endif 106 107 /* 108 * Release a set of thread group credentials. 109 */ 110 static void release_tgcred(struct cred *cred) 111 { 112 #ifdef CONFIG_KEYS 113 struct thread_group_cred *tgcred = cred->tgcred; 114 115 if (atomic_dec_and_test(&tgcred->usage)) 116 call_rcu(&tgcred->rcu, release_tgcred_rcu); 117 #endif 118 } 119 120 /* 121 * The RCU callback to actually dispose of a set of credentials 122 */ 123 static void put_cred_rcu(struct rcu_head *rcu) 124 { 125 struct cred *cred = container_of(rcu, struct cred, rcu); 126 127 kdebug("put_cred_rcu(%p)", cred); 128 129 #ifdef CONFIG_DEBUG_CREDENTIALS 130 if (cred->magic != CRED_MAGIC_DEAD || 131 atomic_read(&cred->usage) != 0 || 132 read_cred_subscribers(cred) != 0) 133 panic("CRED: put_cred_rcu() sees %p with" 134 " mag %x, put %p, usage %d, subscr %d\n", 135 cred, cred->magic, cred->put_addr, 136 atomic_read(&cred->usage), 137 read_cred_subscribers(cred)); 138 #else 139 if (atomic_read(&cred->usage) != 0) 140 panic("CRED: put_cred_rcu() sees %p with usage %d\n", 141 cred, atomic_read(&cred->usage)); 142 #endif 143 144 security_cred_free(cred); 145 key_put(cred->thread_keyring); 146 key_put(cred->request_key_auth); 147 release_tgcred(cred); 148 if (cred->group_info) 149 put_group_info(cred->group_info); 150 free_uid(cred->user); 151 kmem_cache_free(cred_jar, cred); 152 } 153 154 /** 155 * __put_cred - Destroy a set of credentials 156 * @cred: The record to release 157 * 158 * Destroy a set of credentials on which no references remain. 159 */ 160 void __put_cred(struct cred *cred) 161 { 162 kdebug("__put_cred(%p{%d,%d})", cred, 163 atomic_read(&cred->usage), 164 read_cred_subscribers(cred)); 165 166 BUG_ON(atomic_read(&cred->usage) != 0); 167 #ifdef CONFIG_DEBUG_CREDENTIALS 168 BUG_ON(read_cred_subscribers(cred) != 0); 169 cred->magic = CRED_MAGIC_DEAD; 170 cred->put_addr = __builtin_return_address(0); 171 #endif 172 BUG_ON(cred == current->cred); 173 BUG_ON(cred == current->real_cred); 174 175 call_rcu(&cred->rcu, put_cred_rcu); 176 } 177 EXPORT_SYMBOL(__put_cred); 178 179 /* 180 * Clean up a task's credentials when it exits 181 */ 182 void exit_creds(struct task_struct *tsk) 183 { 184 struct cred *cred; 185 186 kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred, 187 atomic_read(&tsk->cred->usage), 188 read_cred_subscribers(tsk->cred)); 189 190 cred = (struct cred *) tsk->real_cred; 191 tsk->real_cred = NULL; 192 validate_creds(cred); 193 alter_cred_subscribers(cred, -1); 194 put_cred(cred); 195 196 cred = (struct cred *) tsk->cred; 197 tsk->cred = NULL; 198 validate_creds(cred); 199 alter_cred_subscribers(cred, -1); 200 put_cred(cred); 201 202 cred = (struct cred *) tsk->replacement_session_keyring; 203 if (cred) { 204 tsk->replacement_session_keyring = NULL; 205 validate_creds(cred); 206 put_cred(cred); 207 } 208 } 209 210 /** 211 * get_task_cred - Get another task's objective credentials 212 * @task: The task to query 213 * 214 * Get the objective credentials of a task, pinning them so that they can't go 215 * away. Accessing a task's credentials directly is not permitted. 216 * 217 * The caller must also make sure task doesn't get deleted, either by holding a 218 * ref on task or by holding tasklist_lock to prevent it from being unlinked. 219 */ 220 const struct cred *get_task_cred(struct task_struct *task) 221 { 222 const struct cred *cred; 223 224 rcu_read_lock(); 225 226 do { 227 cred = __task_cred((task)); 228 BUG_ON(!cred); 229 } while (!atomic_inc_not_zero(&((struct cred *)cred)->usage)); 230 231 rcu_read_unlock(); 232 return cred; 233 } 234 235 /* 236 * Allocate blank credentials, such that the credentials can be filled in at a 237 * later date without risk of ENOMEM. 238 */ 239 struct cred *cred_alloc_blank(void) 240 { 241 struct cred *new; 242 243 new = kmem_cache_zalloc(cred_jar, GFP_KERNEL); 244 if (!new) 245 return NULL; 246 247 #ifdef CONFIG_KEYS 248 new->tgcred = kzalloc(sizeof(*new->tgcred), GFP_KERNEL); 249 if (!new->tgcred) { 250 kmem_cache_free(cred_jar, new); 251 return NULL; 252 } 253 atomic_set(&new->tgcred->usage, 1); 254 #endif 255 256 atomic_set(&new->usage, 1); 257 #ifdef CONFIG_DEBUG_CREDENTIALS 258 new->magic = CRED_MAGIC; 259 #endif 260 261 if (security_cred_alloc_blank(new, GFP_KERNEL) < 0) 262 goto error; 263 264 return new; 265 266 error: 267 abort_creds(new); 268 return NULL; 269 } 270 271 /** 272 * prepare_creds - Prepare a new set of credentials for modification 273 * 274 * Prepare a new set of task credentials for modification. A task's creds 275 * shouldn't generally be modified directly, therefore this function is used to 276 * prepare a new copy, which the caller then modifies and then commits by 277 * calling commit_creds(). 278 * 279 * Preparation involves making a copy of the objective creds for modification. 280 * 281 * Returns a pointer to the new creds-to-be if successful, NULL otherwise. 282 * 283 * Call commit_creds() or abort_creds() to clean up. 284 */ 285 struct cred *prepare_creds(void) 286 { 287 struct task_struct *task = current; 288 const struct cred *old; 289 struct cred *new; 290 291 validate_process_creds(); 292 293 new = kmem_cache_alloc(cred_jar, GFP_KERNEL); 294 if (!new) 295 return NULL; 296 297 kdebug("prepare_creds() alloc %p", new); 298 299 old = task->cred; 300 memcpy(new, old, sizeof(struct cred)); 301 302 atomic_set(&new->usage, 1); 303 set_cred_subscribers(new, 0); 304 get_group_info(new->group_info); 305 get_uid(new->user); 306 307 #ifdef CONFIG_KEYS 308 key_get(new->thread_keyring); 309 key_get(new->request_key_auth); 310 atomic_inc(&new->tgcred->usage); 311 #endif 312 313 #ifdef CONFIG_SECURITY 314 new->security = NULL; 315 #endif 316 317 if (security_prepare_creds(new, old, GFP_KERNEL) < 0) 318 goto error; 319 validate_creds(new); 320 return new; 321 322 error: 323 abort_creds(new); 324 return NULL; 325 } 326 EXPORT_SYMBOL(prepare_creds); 327 328 /* 329 * Prepare credentials for current to perform an execve() 330 * - The caller must hold ->cred_guard_mutex 331 */ 332 struct cred *prepare_exec_creds(void) 333 { 334 struct thread_group_cred *tgcred = NULL; 335 struct cred *new; 336 337 #ifdef CONFIG_KEYS 338 tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL); 339 if (!tgcred) 340 return NULL; 341 #endif 342 343 new = prepare_creds(); 344 if (!new) { 345 kfree(tgcred); 346 return new; 347 } 348 349 #ifdef CONFIG_KEYS 350 /* newly exec'd tasks don't get a thread keyring */ 351 key_put(new->thread_keyring); 352 new->thread_keyring = NULL; 353 354 /* create a new per-thread-group creds for all this set of threads to 355 * share */ 356 memcpy(tgcred, new->tgcred, sizeof(struct thread_group_cred)); 357 358 atomic_set(&tgcred->usage, 1); 359 spin_lock_init(&tgcred->lock); 360 361 /* inherit the session keyring; new process keyring */ 362 key_get(tgcred->session_keyring); 363 tgcred->process_keyring = NULL; 364 365 release_tgcred(new); 366 new->tgcred = tgcred; 367 #endif 368 369 return new; 370 } 371 372 /* 373 * Copy credentials for the new process created by fork() 374 * 375 * We share if we can, but under some circumstances we have to generate a new 376 * set. 377 * 378 * The new process gets the current process's subjective credentials as its 379 * objective and subjective credentials 380 */ 381 int copy_creds(struct task_struct *p, unsigned long clone_flags) 382 { 383 #ifdef CONFIG_KEYS 384 struct thread_group_cred *tgcred; 385 #endif 386 struct cred *new; 387 int ret; 388 389 if ( 390 #ifdef CONFIG_KEYS 391 !p->cred->thread_keyring && 392 #endif 393 clone_flags & CLONE_THREAD 394 ) { 395 p->real_cred = get_cred(p->cred); 396 get_cred(p->cred); 397 alter_cred_subscribers(p->cred, 2); 398 kdebug("share_creds(%p{%d,%d})", 399 p->cred, atomic_read(&p->cred->usage), 400 read_cred_subscribers(p->cred)); 401 atomic_inc(&p->cred->user->processes); 402 return 0; 403 } 404 405 new = prepare_creds(); 406 if (!new) 407 return -ENOMEM; 408 409 if (clone_flags & CLONE_NEWUSER) { 410 ret = create_user_ns(new); 411 if (ret < 0) 412 goto error_put; 413 } 414 415 /* cache user_ns in cred. Doesn't need a refcount because it will 416 * stay pinned by cred->user 417 */ 418 new->user_ns = new->user->user_ns; 419 420 #ifdef CONFIG_KEYS 421 /* new threads get their own thread keyrings if their parent already 422 * had one */ 423 if (new->thread_keyring) { 424 key_put(new->thread_keyring); 425 new->thread_keyring = NULL; 426 if (clone_flags & CLONE_THREAD) 427 install_thread_keyring_to_cred(new); 428 } 429 430 /* we share the process and session keyrings between all the threads in 431 * a process - this is slightly icky as we violate COW credentials a 432 * bit */ 433 if (!(clone_flags & CLONE_THREAD)) { 434 tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL); 435 if (!tgcred) { 436 ret = -ENOMEM; 437 goto error_put; 438 } 439 atomic_set(&tgcred->usage, 1); 440 spin_lock_init(&tgcred->lock); 441 tgcred->process_keyring = NULL; 442 tgcred->session_keyring = key_get(new->tgcred->session_keyring); 443 444 release_tgcred(new); 445 new->tgcred = tgcred; 446 } 447 #endif 448 449 atomic_inc(&new->user->processes); 450 p->cred = p->real_cred = get_cred(new); 451 alter_cred_subscribers(new, 2); 452 validate_creds(new); 453 return 0; 454 455 error_put: 456 put_cred(new); 457 return ret; 458 } 459 460 /** 461 * commit_creds - Install new credentials upon the current task 462 * @new: The credentials to be assigned 463 * 464 * Install a new set of credentials to the current task, using RCU to replace 465 * the old set. Both the objective and the subjective credentials pointers are 466 * updated. This function may not be called if the subjective credentials are 467 * in an overridden state. 468 * 469 * This function eats the caller's reference to the new credentials. 470 * 471 * Always returns 0 thus allowing this function to be tail-called at the end 472 * of, say, sys_setgid(). 473 */ 474 int commit_creds(struct cred *new) 475 { 476 struct task_struct *task = current; 477 const struct cred *old = task->real_cred; 478 479 kdebug("commit_creds(%p{%d,%d})", new, 480 atomic_read(&new->usage), 481 read_cred_subscribers(new)); 482 483 BUG_ON(task->cred != old); 484 #ifdef CONFIG_DEBUG_CREDENTIALS 485 BUG_ON(read_cred_subscribers(old) < 2); 486 validate_creds(old); 487 validate_creds(new); 488 #endif 489 BUG_ON(atomic_read(&new->usage) < 1); 490 491 get_cred(new); /* we will require a ref for the subj creds too */ 492 493 /* dumpability changes */ 494 if (old->euid != new->euid || 495 old->egid != new->egid || 496 old->fsuid != new->fsuid || 497 old->fsgid != new->fsgid || 498 !cap_issubset(new->cap_permitted, old->cap_permitted)) { 499 if (task->mm) 500 set_dumpable(task->mm, suid_dumpable); 501 task->pdeath_signal = 0; 502 smp_wmb(); 503 } 504 505 /* alter the thread keyring */ 506 if (new->fsuid != old->fsuid) 507 key_fsuid_changed(task); 508 if (new->fsgid != old->fsgid) 509 key_fsgid_changed(task); 510 511 /* do it 512 * RLIMIT_NPROC limits on user->processes have already been checked 513 * in set_user(). 514 */ 515 alter_cred_subscribers(new, 2); 516 if (new->user != old->user) 517 atomic_inc(&new->user->processes); 518 rcu_assign_pointer(task->real_cred, new); 519 rcu_assign_pointer(task->cred, new); 520 if (new->user != old->user) 521 atomic_dec(&old->user->processes); 522 alter_cred_subscribers(old, -2); 523 524 /* send notifications */ 525 if (new->uid != old->uid || 526 new->euid != old->euid || 527 new->suid != old->suid || 528 new->fsuid != old->fsuid) 529 proc_id_connector(task, PROC_EVENT_UID); 530 531 if (new->gid != old->gid || 532 new->egid != old->egid || 533 new->sgid != old->sgid || 534 new->fsgid != old->fsgid) 535 proc_id_connector(task, PROC_EVENT_GID); 536 537 /* release the old obj and subj refs both */ 538 put_cred(old); 539 put_cred(old); 540 return 0; 541 } 542 EXPORT_SYMBOL(commit_creds); 543 544 /** 545 * abort_creds - Discard a set of credentials and unlock the current task 546 * @new: The credentials that were going to be applied 547 * 548 * Discard a set of credentials that were under construction and unlock the 549 * current task. 550 */ 551 void abort_creds(struct cred *new) 552 { 553 kdebug("abort_creds(%p{%d,%d})", new, 554 atomic_read(&new->usage), 555 read_cred_subscribers(new)); 556 557 #ifdef CONFIG_DEBUG_CREDENTIALS 558 BUG_ON(read_cred_subscribers(new) != 0); 559 #endif 560 BUG_ON(atomic_read(&new->usage) < 1); 561 put_cred(new); 562 } 563 EXPORT_SYMBOL(abort_creds); 564 565 /** 566 * override_creds - Override the current process's subjective credentials 567 * @new: The credentials to be assigned 568 * 569 * Install a set of temporary override subjective credentials on the current 570 * process, returning the old set for later reversion. 571 */ 572 const struct cred *override_creds(const struct cred *new) 573 { 574 const struct cred *old = current->cred; 575 576 kdebug("override_creds(%p{%d,%d})", new, 577 atomic_read(&new->usage), 578 read_cred_subscribers(new)); 579 580 validate_creds(old); 581 validate_creds(new); 582 get_cred(new); 583 alter_cred_subscribers(new, 1); 584 rcu_assign_pointer(current->cred, new); 585 alter_cred_subscribers(old, -1); 586 587 kdebug("override_creds() = %p{%d,%d}", old, 588 atomic_read(&old->usage), 589 read_cred_subscribers(old)); 590 return old; 591 } 592 EXPORT_SYMBOL(override_creds); 593 594 /** 595 * revert_creds - Revert a temporary subjective credentials override 596 * @old: The credentials to be restored 597 * 598 * Revert a temporary set of override subjective credentials to an old set, 599 * discarding the override set. 600 */ 601 void revert_creds(const struct cred *old) 602 { 603 const struct cred *override = current->cred; 604 605 kdebug("revert_creds(%p{%d,%d})", old, 606 atomic_read(&old->usage), 607 read_cred_subscribers(old)); 608 609 validate_creds(old); 610 validate_creds(override); 611 alter_cred_subscribers(old, 1); 612 rcu_assign_pointer(current->cred, old); 613 alter_cred_subscribers(override, -1); 614 put_cred(override); 615 } 616 EXPORT_SYMBOL(revert_creds); 617 618 /* 619 * initialise the credentials stuff 620 */ 621 void __init cred_init(void) 622 { 623 /* allocate a slab in which we can store credentials */ 624 cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 625 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 626 } 627 628 /** 629 * prepare_kernel_cred - Prepare a set of credentials for a kernel service 630 * @daemon: A userspace daemon to be used as a reference 631 * 632 * Prepare a set of credentials for a kernel service. This can then be used to 633 * override a task's own credentials so that work can be done on behalf of that 634 * task that requires a different subjective context. 635 * 636 * @daemon is used to provide a base for the security record, but can be NULL. 637 * If @daemon is supplied, then the security data will be derived from that; 638 * otherwise they'll be set to 0 and no groups, full capabilities and no keys. 639 * 640 * The caller may change these controls afterwards if desired. 641 * 642 * Returns the new credentials or NULL if out of memory. 643 * 644 * Does not take, and does not return holding current->cred_replace_mutex. 645 */ 646 struct cred *prepare_kernel_cred(struct task_struct *daemon) 647 { 648 #ifdef CONFIG_KEYS 649 struct thread_group_cred *tgcred; 650 #endif 651 const struct cred *old; 652 struct cred *new; 653 654 new = kmem_cache_alloc(cred_jar, GFP_KERNEL); 655 if (!new) 656 return NULL; 657 658 #ifdef CONFIG_KEYS 659 tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL); 660 if (!tgcred) { 661 kmem_cache_free(cred_jar, new); 662 return NULL; 663 } 664 #endif 665 666 kdebug("prepare_kernel_cred() alloc %p", new); 667 668 if (daemon) 669 old = get_task_cred(daemon); 670 else 671 old = get_cred(&init_cred); 672 673 validate_creds(old); 674 675 *new = *old; 676 atomic_set(&new->usage, 1); 677 set_cred_subscribers(new, 0); 678 get_uid(new->user); 679 get_group_info(new->group_info); 680 681 #ifdef CONFIG_KEYS 682 atomic_set(&tgcred->usage, 1); 683 spin_lock_init(&tgcred->lock); 684 tgcred->process_keyring = NULL; 685 tgcred->session_keyring = NULL; 686 new->tgcred = tgcred; 687 new->request_key_auth = NULL; 688 new->thread_keyring = NULL; 689 new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING; 690 #endif 691 692 #ifdef CONFIG_SECURITY 693 new->security = NULL; 694 #endif 695 if (security_prepare_creds(new, old, GFP_KERNEL) < 0) 696 goto error; 697 698 put_cred(old); 699 validate_creds(new); 700 return new; 701 702 error: 703 put_cred(new); 704 put_cred(old); 705 return NULL; 706 } 707 EXPORT_SYMBOL(prepare_kernel_cred); 708 709 /** 710 * set_security_override - Set the security ID in a set of credentials 711 * @new: The credentials to alter 712 * @secid: The LSM security ID to set 713 * 714 * Set the LSM security ID in a set of credentials so that the subjective 715 * security is overridden when an alternative set of credentials is used. 716 */ 717 int set_security_override(struct cred *new, u32 secid) 718 { 719 return security_kernel_act_as(new, secid); 720 } 721 EXPORT_SYMBOL(set_security_override); 722 723 /** 724 * set_security_override_from_ctx - Set the security ID in a set of credentials 725 * @new: The credentials to alter 726 * @secctx: The LSM security context to generate the security ID from. 727 * 728 * Set the LSM security ID in a set of credentials so that the subjective 729 * security is overridden when an alternative set of credentials is used. The 730 * security ID is specified in string form as a security context to be 731 * interpreted by the LSM. 732 */ 733 int set_security_override_from_ctx(struct cred *new, const char *secctx) 734 { 735 u32 secid; 736 int ret; 737 738 ret = security_secctx_to_secid(secctx, strlen(secctx), &secid); 739 if (ret < 0) 740 return ret; 741 742 return set_security_override(new, secid); 743 } 744 EXPORT_SYMBOL(set_security_override_from_ctx); 745 746 /** 747 * set_create_files_as - Set the LSM file create context in a set of credentials 748 * @new: The credentials to alter 749 * @inode: The inode to take the context from 750 * 751 * Change the LSM file creation context in a set of credentials to be the same 752 * as the object context of the specified inode, so that the new inodes have 753 * the same MAC context as that inode. 754 */ 755 int set_create_files_as(struct cred *new, struct inode *inode) 756 { 757 new->fsuid = inode->i_uid; 758 new->fsgid = inode->i_gid; 759 return security_kernel_create_files_as(new, inode); 760 } 761 EXPORT_SYMBOL(set_create_files_as); 762 763 #ifdef CONFIG_DEBUG_CREDENTIALS 764 765 bool creds_are_invalid(const struct cred *cred) 766 { 767 if (cred->magic != CRED_MAGIC) 768 return true; 769 #ifdef CONFIG_SECURITY_SELINUX 770 /* 771 * cred->security == NULL if security_cred_alloc_blank() or 772 * security_prepare_creds() returned an error. 773 */ 774 if (selinux_is_enabled() && cred->security) { 775 if ((unsigned long) cred->security < PAGE_SIZE) 776 return true; 777 if ((*(u32 *)cred->security & 0xffffff00) == 778 (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)) 779 return true; 780 } 781 #endif 782 return false; 783 } 784 EXPORT_SYMBOL(creds_are_invalid); 785 786 /* 787 * dump invalid credentials 788 */ 789 static void dump_invalid_creds(const struct cred *cred, const char *label, 790 const struct task_struct *tsk) 791 { 792 printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n", 793 label, cred, 794 cred == &init_cred ? "[init]" : "", 795 cred == tsk->real_cred ? "[real]" : "", 796 cred == tsk->cred ? "[eff]" : ""); 797 printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n", 798 cred->magic, cred->put_addr); 799 printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n", 800 atomic_read(&cred->usage), 801 read_cred_subscribers(cred)); 802 printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n", 803 cred->uid, cred->euid, cred->suid, cred->fsuid); 804 printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n", 805 cred->gid, cred->egid, cred->sgid, cred->fsgid); 806 #ifdef CONFIG_SECURITY 807 printk(KERN_ERR "CRED: ->security is %p\n", cred->security); 808 if ((unsigned long) cred->security >= PAGE_SIZE && 809 (((unsigned long) cred->security & 0xffffff00) != 810 (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))) 811 printk(KERN_ERR "CRED: ->security {%x, %x}\n", 812 ((u32*)cred->security)[0], 813 ((u32*)cred->security)[1]); 814 #endif 815 } 816 817 /* 818 * report use of invalid credentials 819 */ 820 void __invalid_creds(const struct cred *cred, const char *file, unsigned line) 821 { 822 printk(KERN_ERR "CRED: Invalid credentials\n"); 823 printk(KERN_ERR "CRED: At %s:%u\n", file, line); 824 dump_invalid_creds(cred, "Specified", current); 825 BUG(); 826 } 827 EXPORT_SYMBOL(__invalid_creds); 828 829 /* 830 * check the credentials on a process 831 */ 832 void __validate_process_creds(struct task_struct *tsk, 833 const char *file, unsigned line) 834 { 835 if (tsk->cred == tsk->real_cred) { 836 if (unlikely(read_cred_subscribers(tsk->cred) < 2 || 837 creds_are_invalid(tsk->cred))) 838 goto invalid_creds; 839 } else { 840 if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 || 841 read_cred_subscribers(tsk->cred) < 1 || 842 creds_are_invalid(tsk->real_cred) || 843 creds_are_invalid(tsk->cred))) 844 goto invalid_creds; 845 } 846 return; 847 848 invalid_creds: 849 printk(KERN_ERR "CRED: Invalid process credentials\n"); 850 printk(KERN_ERR "CRED: At %s:%u\n", file, line); 851 852 dump_invalid_creds(tsk->real_cred, "Real", tsk); 853 if (tsk->cred != tsk->real_cred) 854 dump_invalid_creds(tsk->cred, "Effective", tsk); 855 else 856 printk(KERN_ERR "CRED: Effective creds == Real creds\n"); 857 BUG(); 858 } 859 EXPORT_SYMBOL(__validate_process_creds); 860 861 /* 862 * check creds for do_exit() 863 */ 864 void validate_creds_for_do_exit(struct task_struct *tsk) 865 { 866 kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})", 867 tsk->real_cred, tsk->cred, 868 atomic_read(&tsk->cred->usage), 869 read_cred_subscribers(tsk->cred)); 870 871 __validate_process_creds(tsk, __FILE__, __LINE__); 872 } 873 874 #endif /* CONFIG_DEBUG_CREDENTIALS */ 875