1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org> 4 * 5 * Fixes from William Schumacher incorporated on 15 March 2001. 6 * (Reported by Charles Bertsch, <CBertsch@microtest.com>). 7 */ 8 9 /* 10 * This file contains generic functions for manipulating 11 * POSIX 1003.1e draft standard 17 ACLs. 12 */ 13 14 #include <linux/kernel.h> 15 #include <linux/slab.h> 16 #include <linux/atomic.h> 17 #include <linux/fs.h> 18 #include <linux/sched.h> 19 #include <linux/cred.h> 20 #include <linux/posix_acl.h> 21 #include <linux/posix_acl_xattr.h> 22 #include <linux/xattr.h> 23 #include <linux/export.h> 24 #include <linux/user_namespace.h> 25 26 static struct posix_acl **acl_by_type(struct inode *inode, int type) 27 { 28 switch (type) { 29 case ACL_TYPE_ACCESS: 30 return &inode->i_acl; 31 case ACL_TYPE_DEFAULT: 32 return &inode->i_default_acl; 33 default: 34 BUG(); 35 } 36 } 37 38 struct posix_acl *get_cached_acl(struct inode *inode, int type) 39 { 40 struct posix_acl **p = acl_by_type(inode, type); 41 struct posix_acl *acl; 42 43 for (;;) { 44 rcu_read_lock(); 45 acl = rcu_dereference(*p); 46 if (!acl || is_uncached_acl(acl) || 47 refcount_inc_not_zero(&acl->a_refcount)) 48 break; 49 rcu_read_unlock(); 50 cpu_relax(); 51 } 52 rcu_read_unlock(); 53 return acl; 54 } 55 EXPORT_SYMBOL(get_cached_acl); 56 57 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type) 58 { 59 return rcu_dereference(*acl_by_type(inode, type)); 60 } 61 EXPORT_SYMBOL(get_cached_acl_rcu); 62 63 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl) 64 { 65 struct posix_acl **p = acl_by_type(inode, type); 66 struct posix_acl *old; 67 68 old = xchg(p, posix_acl_dup(acl)); 69 if (!is_uncached_acl(old)) 70 posix_acl_release(old); 71 } 72 EXPORT_SYMBOL(set_cached_acl); 73 74 static void __forget_cached_acl(struct posix_acl **p) 75 { 76 struct posix_acl *old; 77 78 old = xchg(p, ACL_NOT_CACHED); 79 if (!is_uncached_acl(old)) 80 posix_acl_release(old); 81 } 82 83 void forget_cached_acl(struct inode *inode, int type) 84 { 85 __forget_cached_acl(acl_by_type(inode, type)); 86 } 87 EXPORT_SYMBOL(forget_cached_acl); 88 89 void forget_all_cached_acls(struct inode *inode) 90 { 91 __forget_cached_acl(&inode->i_acl); 92 __forget_cached_acl(&inode->i_default_acl); 93 } 94 EXPORT_SYMBOL(forget_all_cached_acls); 95 96 struct posix_acl *get_acl(struct inode *inode, int type) 97 { 98 void *sentinel; 99 struct posix_acl **p; 100 struct posix_acl *acl; 101 102 /* 103 * The sentinel is used to detect when another operation like 104 * set_cached_acl() or forget_cached_acl() races with get_acl(). 105 * It is guaranteed that is_uncached_acl(sentinel) is true. 106 */ 107 108 acl = get_cached_acl(inode, type); 109 if (!is_uncached_acl(acl)) 110 return acl; 111 112 if (!IS_POSIXACL(inode)) 113 return NULL; 114 115 sentinel = uncached_acl_sentinel(current); 116 p = acl_by_type(inode, type); 117 118 /* 119 * If the ACL isn't being read yet, set our sentinel. Otherwise, the 120 * current value of the ACL will not be ACL_NOT_CACHED and so our own 121 * sentinel will not be set; another task will update the cache. We 122 * could wait for that other task to complete its job, but it's easier 123 * to just call ->get_acl to fetch the ACL ourself. (This is going to 124 * be an unlikely race.) 125 */ 126 if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED) 127 /* fall through */ ; 128 129 /* 130 * Normally, the ACL returned by ->get_acl will be cached. 131 * A filesystem can prevent that by calling 132 * forget_cached_acl(inode, type) in ->get_acl. 133 * 134 * If the filesystem doesn't have a get_acl() function at all, we'll 135 * just create the negative cache entry. 136 */ 137 if (!inode->i_op->get_acl) { 138 set_cached_acl(inode, type, NULL); 139 return NULL; 140 } 141 acl = inode->i_op->get_acl(inode, type); 142 143 if (IS_ERR(acl)) { 144 /* 145 * Remove our sentinel so that we don't block future attempts 146 * to cache the ACL. 147 */ 148 cmpxchg(p, sentinel, ACL_NOT_CACHED); 149 return acl; 150 } 151 152 /* 153 * Cache the result, but only if our sentinel is still in place. 154 */ 155 posix_acl_dup(acl); 156 if (unlikely(cmpxchg(p, sentinel, acl) != sentinel)) 157 posix_acl_release(acl); 158 return acl; 159 } 160 EXPORT_SYMBOL(get_acl); 161 162 /* 163 * Init a fresh posix_acl 164 */ 165 void 166 posix_acl_init(struct posix_acl *acl, int count) 167 { 168 refcount_set(&acl->a_refcount, 1); 169 acl->a_count = count; 170 } 171 EXPORT_SYMBOL(posix_acl_init); 172 173 /* 174 * Allocate a new ACL with the specified number of entries. 175 */ 176 struct posix_acl * 177 posix_acl_alloc(int count, gfp_t flags) 178 { 179 const size_t size = sizeof(struct posix_acl) + 180 count * sizeof(struct posix_acl_entry); 181 struct posix_acl *acl = kmalloc(size, flags); 182 if (acl) 183 posix_acl_init(acl, count); 184 return acl; 185 } 186 EXPORT_SYMBOL(posix_acl_alloc); 187 188 /* 189 * Clone an ACL. 190 */ 191 static struct posix_acl * 192 posix_acl_clone(const struct posix_acl *acl, gfp_t flags) 193 { 194 struct posix_acl *clone = NULL; 195 196 if (acl) { 197 int size = sizeof(struct posix_acl) + acl->a_count * 198 sizeof(struct posix_acl_entry); 199 clone = kmemdup(acl, size, flags); 200 if (clone) 201 refcount_set(&clone->a_refcount, 1); 202 } 203 return clone; 204 } 205 206 /* 207 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise. 208 */ 209 int 210 posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl) 211 { 212 const struct posix_acl_entry *pa, *pe; 213 int state = ACL_USER_OBJ; 214 int needs_mask = 0; 215 216 FOREACH_ACL_ENTRY(pa, acl, pe) { 217 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE)) 218 return -EINVAL; 219 switch (pa->e_tag) { 220 case ACL_USER_OBJ: 221 if (state == ACL_USER_OBJ) { 222 state = ACL_USER; 223 break; 224 } 225 return -EINVAL; 226 227 case ACL_USER: 228 if (state != ACL_USER) 229 return -EINVAL; 230 if (!kuid_has_mapping(user_ns, pa->e_uid)) 231 return -EINVAL; 232 needs_mask = 1; 233 break; 234 235 case ACL_GROUP_OBJ: 236 if (state == ACL_USER) { 237 state = ACL_GROUP; 238 break; 239 } 240 return -EINVAL; 241 242 case ACL_GROUP: 243 if (state != ACL_GROUP) 244 return -EINVAL; 245 if (!kgid_has_mapping(user_ns, pa->e_gid)) 246 return -EINVAL; 247 needs_mask = 1; 248 break; 249 250 case ACL_MASK: 251 if (state != ACL_GROUP) 252 return -EINVAL; 253 state = ACL_OTHER; 254 break; 255 256 case ACL_OTHER: 257 if (state == ACL_OTHER || 258 (state == ACL_GROUP && !needs_mask)) { 259 state = 0; 260 break; 261 } 262 return -EINVAL; 263 264 default: 265 return -EINVAL; 266 } 267 } 268 if (state == 0) 269 return 0; 270 return -EINVAL; 271 } 272 EXPORT_SYMBOL(posix_acl_valid); 273 274 /* 275 * Returns 0 if the acl can be exactly represented in the traditional 276 * file mode permission bits, or else 1. Returns -E... on error. 277 */ 278 int 279 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p) 280 { 281 const struct posix_acl_entry *pa, *pe; 282 umode_t mode = 0; 283 int not_equiv = 0; 284 285 /* 286 * A null ACL can always be presented as mode bits. 287 */ 288 if (!acl) 289 return 0; 290 291 FOREACH_ACL_ENTRY(pa, acl, pe) { 292 switch (pa->e_tag) { 293 case ACL_USER_OBJ: 294 mode |= (pa->e_perm & S_IRWXO) << 6; 295 break; 296 case ACL_GROUP_OBJ: 297 mode |= (pa->e_perm & S_IRWXO) << 3; 298 break; 299 case ACL_OTHER: 300 mode |= pa->e_perm & S_IRWXO; 301 break; 302 case ACL_MASK: 303 mode = (mode & ~S_IRWXG) | 304 ((pa->e_perm & S_IRWXO) << 3); 305 not_equiv = 1; 306 break; 307 case ACL_USER: 308 case ACL_GROUP: 309 not_equiv = 1; 310 break; 311 default: 312 return -EINVAL; 313 } 314 } 315 if (mode_p) 316 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 317 return not_equiv; 318 } 319 EXPORT_SYMBOL(posix_acl_equiv_mode); 320 321 /* 322 * Create an ACL representing the file mode permission bits of an inode. 323 */ 324 struct posix_acl * 325 posix_acl_from_mode(umode_t mode, gfp_t flags) 326 { 327 struct posix_acl *acl = posix_acl_alloc(3, flags); 328 if (!acl) 329 return ERR_PTR(-ENOMEM); 330 331 acl->a_entries[0].e_tag = ACL_USER_OBJ; 332 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6; 333 334 acl->a_entries[1].e_tag = ACL_GROUP_OBJ; 335 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3; 336 337 acl->a_entries[2].e_tag = ACL_OTHER; 338 acl->a_entries[2].e_perm = (mode & S_IRWXO); 339 return acl; 340 } 341 EXPORT_SYMBOL(posix_acl_from_mode); 342 343 /* 344 * Return 0 if current is granted want access to the inode 345 * by the acl. Returns -E... otherwise. 346 */ 347 int 348 posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want) 349 { 350 const struct posix_acl_entry *pa, *pe, *mask_obj; 351 int found = 0; 352 353 want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK; 354 355 FOREACH_ACL_ENTRY(pa, acl, pe) { 356 switch(pa->e_tag) { 357 case ACL_USER_OBJ: 358 /* (May have been checked already) */ 359 if (uid_eq(inode->i_uid, current_fsuid())) 360 goto check_perm; 361 break; 362 case ACL_USER: 363 if (uid_eq(pa->e_uid, current_fsuid())) 364 goto mask; 365 break; 366 case ACL_GROUP_OBJ: 367 if (in_group_p(inode->i_gid)) { 368 found = 1; 369 if ((pa->e_perm & want) == want) 370 goto mask; 371 } 372 break; 373 case ACL_GROUP: 374 if (in_group_p(pa->e_gid)) { 375 found = 1; 376 if ((pa->e_perm & want) == want) 377 goto mask; 378 } 379 break; 380 case ACL_MASK: 381 break; 382 case ACL_OTHER: 383 if (found) 384 return -EACCES; 385 else 386 goto check_perm; 387 default: 388 return -EIO; 389 } 390 } 391 return -EIO; 392 393 mask: 394 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) { 395 if (mask_obj->e_tag == ACL_MASK) { 396 if ((pa->e_perm & mask_obj->e_perm & want) == want) 397 return 0; 398 return -EACCES; 399 } 400 } 401 402 check_perm: 403 if ((pa->e_perm & want) == want) 404 return 0; 405 return -EACCES; 406 } 407 408 /* 409 * Modify acl when creating a new inode. The caller must ensure the acl is 410 * only referenced once. 411 * 412 * mode_p initially must contain the mode parameter to the open() / creat() 413 * system calls. All permissions that are not granted by the acl are removed. 414 * The permissions in the acl are changed to reflect the mode_p parameter. 415 */ 416 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p) 417 { 418 struct posix_acl_entry *pa, *pe; 419 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 420 umode_t mode = *mode_p; 421 int not_equiv = 0; 422 423 /* assert(atomic_read(acl->a_refcount) == 1); */ 424 425 FOREACH_ACL_ENTRY(pa, acl, pe) { 426 switch(pa->e_tag) { 427 case ACL_USER_OBJ: 428 pa->e_perm &= (mode >> 6) | ~S_IRWXO; 429 mode &= (pa->e_perm << 6) | ~S_IRWXU; 430 break; 431 432 case ACL_USER: 433 case ACL_GROUP: 434 not_equiv = 1; 435 break; 436 437 case ACL_GROUP_OBJ: 438 group_obj = pa; 439 break; 440 441 case ACL_OTHER: 442 pa->e_perm &= mode | ~S_IRWXO; 443 mode &= pa->e_perm | ~S_IRWXO; 444 break; 445 446 case ACL_MASK: 447 mask_obj = pa; 448 not_equiv = 1; 449 break; 450 451 default: 452 return -EIO; 453 } 454 } 455 456 if (mask_obj) { 457 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 458 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG; 459 } else { 460 if (!group_obj) 461 return -EIO; 462 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 463 mode &= (group_obj->e_perm << 3) | ~S_IRWXG; 464 } 465 466 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 467 return not_equiv; 468 } 469 470 /* 471 * Modify the ACL for the chmod syscall. 472 */ 473 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode) 474 { 475 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 476 struct posix_acl_entry *pa, *pe; 477 478 /* assert(atomic_read(acl->a_refcount) == 1); */ 479 480 FOREACH_ACL_ENTRY(pa, acl, pe) { 481 switch(pa->e_tag) { 482 case ACL_USER_OBJ: 483 pa->e_perm = (mode & S_IRWXU) >> 6; 484 break; 485 486 case ACL_USER: 487 case ACL_GROUP: 488 break; 489 490 case ACL_GROUP_OBJ: 491 group_obj = pa; 492 break; 493 494 case ACL_MASK: 495 mask_obj = pa; 496 break; 497 498 case ACL_OTHER: 499 pa->e_perm = (mode & S_IRWXO); 500 break; 501 502 default: 503 return -EIO; 504 } 505 } 506 507 if (mask_obj) { 508 mask_obj->e_perm = (mode & S_IRWXG) >> 3; 509 } else { 510 if (!group_obj) 511 return -EIO; 512 group_obj->e_perm = (mode & S_IRWXG) >> 3; 513 } 514 515 return 0; 516 } 517 518 int 519 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p) 520 { 521 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 522 int err = -ENOMEM; 523 if (clone) { 524 err = posix_acl_create_masq(clone, mode_p); 525 if (err < 0) { 526 posix_acl_release(clone); 527 clone = NULL; 528 } 529 } 530 posix_acl_release(*acl); 531 *acl = clone; 532 return err; 533 } 534 EXPORT_SYMBOL(__posix_acl_create); 535 536 int 537 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode) 538 { 539 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 540 int err = -ENOMEM; 541 if (clone) { 542 err = __posix_acl_chmod_masq(clone, mode); 543 if (err) { 544 posix_acl_release(clone); 545 clone = NULL; 546 } 547 } 548 posix_acl_release(*acl); 549 *acl = clone; 550 return err; 551 } 552 EXPORT_SYMBOL(__posix_acl_chmod); 553 554 int 555 posix_acl_chmod(struct inode *inode, umode_t mode) 556 { 557 struct posix_acl *acl; 558 int ret = 0; 559 560 if (!IS_POSIXACL(inode)) 561 return 0; 562 if (!inode->i_op->set_acl) 563 return -EOPNOTSUPP; 564 565 acl = get_acl(inode, ACL_TYPE_ACCESS); 566 if (IS_ERR_OR_NULL(acl)) { 567 if (acl == ERR_PTR(-EOPNOTSUPP)) 568 return 0; 569 return PTR_ERR(acl); 570 } 571 572 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode); 573 if (ret) 574 return ret; 575 ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS); 576 posix_acl_release(acl); 577 return ret; 578 } 579 EXPORT_SYMBOL(posix_acl_chmod); 580 581 int 582 posix_acl_create(struct inode *dir, umode_t *mode, 583 struct posix_acl **default_acl, struct posix_acl **acl) 584 { 585 struct posix_acl *p; 586 struct posix_acl *clone; 587 int ret; 588 589 *acl = NULL; 590 *default_acl = NULL; 591 592 if (S_ISLNK(*mode) || !IS_POSIXACL(dir)) 593 return 0; 594 595 p = get_acl(dir, ACL_TYPE_DEFAULT); 596 if (!p || p == ERR_PTR(-EOPNOTSUPP)) { 597 *mode &= ~current_umask(); 598 return 0; 599 } 600 if (IS_ERR(p)) 601 return PTR_ERR(p); 602 603 ret = -ENOMEM; 604 clone = posix_acl_clone(p, GFP_NOFS); 605 if (!clone) 606 goto err_release; 607 608 ret = posix_acl_create_masq(clone, mode); 609 if (ret < 0) 610 goto err_release_clone; 611 612 if (ret == 0) 613 posix_acl_release(clone); 614 else 615 *acl = clone; 616 617 if (!S_ISDIR(*mode)) 618 posix_acl_release(p); 619 else 620 *default_acl = p; 621 622 return 0; 623 624 err_release_clone: 625 posix_acl_release(clone); 626 err_release: 627 posix_acl_release(p); 628 return ret; 629 } 630 EXPORT_SYMBOL_GPL(posix_acl_create); 631 632 /** 633 * posix_acl_update_mode - update mode in set_acl 634 * 635 * Update the file mode when setting an ACL: compute the new file permission 636 * bits based on the ACL. In addition, if the ACL is equivalent to the new 637 * file mode, set *acl to NULL to indicate that no ACL should be set. 638 * 639 * As with chmod, clear the setgit bit if the caller is not in the owning group 640 * or capable of CAP_FSETID (see inode_change_ok). 641 * 642 * Called from set_acl inode operations. 643 */ 644 int posix_acl_update_mode(struct inode *inode, umode_t *mode_p, 645 struct posix_acl **acl) 646 { 647 umode_t mode = inode->i_mode; 648 int error; 649 650 error = posix_acl_equiv_mode(*acl, &mode); 651 if (error < 0) 652 return error; 653 if (error == 0) 654 *acl = NULL; 655 if (!in_group_p(inode->i_gid) && 656 !capable_wrt_inode_uidgid(inode, CAP_FSETID)) 657 mode &= ~S_ISGID; 658 *mode_p = mode; 659 return 0; 660 } 661 EXPORT_SYMBOL(posix_acl_update_mode); 662 663 /* 664 * Fix up the uids and gids in posix acl extended attributes in place. 665 */ 666 static void posix_acl_fix_xattr_userns( 667 struct user_namespace *to, struct user_namespace *from, 668 void *value, size_t size) 669 { 670 struct posix_acl_xattr_header *header = value; 671 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; 672 int count; 673 kuid_t uid; 674 kgid_t gid; 675 676 if (!value) 677 return; 678 if (size < sizeof(struct posix_acl_xattr_header)) 679 return; 680 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 681 return; 682 683 count = posix_acl_xattr_count(size); 684 if (count < 0) 685 return; 686 if (count == 0) 687 return; 688 689 for (end = entry + count; entry != end; entry++) { 690 switch(le16_to_cpu(entry->e_tag)) { 691 case ACL_USER: 692 uid = make_kuid(from, le32_to_cpu(entry->e_id)); 693 entry->e_id = cpu_to_le32(from_kuid(to, uid)); 694 break; 695 case ACL_GROUP: 696 gid = make_kgid(from, le32_to_cpu(entry->e_id)); 697 entry->e_id = cpu_to_le32(from_kgid(to, gid)); 698 break; 699 default: 700 break; 701 } 702 } 703 } 704 705 void posix_acl_fix_xattr_from_user(void *value, size_t size) 706 { 707 struct user_namespace *user_ns = current_user_ns(); 708 if (user_ns == &init_user_ns) 709 return; 710 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size); 711 } 712 713 void posix_acl_fix_xattr_to_user(void *value, size_t size) 714 { 715 struct user_namespace *user_ns = current_user_ns(); 716 if (user_ns == &init_user_ns) 717 return; 718 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size); 719 } 720 721 /* 722 * Convert from extended attribute to in-memory representation. 723 */ 724 struct posix_acl * 725 posix_acl_from_xattr(struct user_namespace *user_ns, 726 const void *value, size_t size) 727 { 728 const struct posix_acl_xattr_header *header = value; 729 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end; 730 int count; 731 struct posix_acl *acl; 732 struct posix_acl_entry *acl_e; 733 734 if (!value) 735 return NULL; 736 if (size < sizeof(struct posix_acl_xattr_header)) 737 return ERR_PTR(-EINVAL); 738 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 739 return ERR_PTR(-EOPNOTSUPP); 740 741 count = posix_acl_xattr_count(size); 742 if (count < 0) 743 return ERR_PTR(-EINVAL); 744 if (count == 0) 745 return NULL; 746 747 acl = posix_acl_alloc(count, GFP_NOFS); 748 if (!acl) 749 return ERR_PTR(-ENOMEM); 750 acl_e = acl->a_entries; 751 752 for (end = entry + count; entry != end; acl_e++, entry++) { 753 acl_e->e_tag = le16_to_cpu(entry->e_tag); 754 acl_e->e_perm = le16_to_cpu(entry->e_perm); 755 756 switch(acl_e->e_tag) { 757 case ACL_USER_OBJ: 758 case ACL_GROUP_OBJ: 759 case ACL_MASK: 760 case ACL_OTHER: 761 break; 762 763 case ACL_USER: 764 acl_e->e_uid = 765 make_kuid(user_ns, 766 le32_to_cpu(entry->e_id)); 767 if (!uid_valid(acl_e->e_uid)) 768 goto fail; 769 break; 770 case ACL_GROUP: 771 acl_e->e_gid = 772 make_kgid(user_ns, 773 le32_to_cpu(entry->e_id)); 774 if (!gid_valid(acl_e->e_gid)) 775 goto fail; 776 break; 777 778 default: 779 goto fail; 780 } 781 } 782 return acl; 783 784 fail: 785 posix_acl_release(acl); 786 return ERR_PTR(-EINVAL); 787 } 788 EXPORT_SYMBOL (posix_acl_from_xattr); 789 790 /* 791 * Convert from in-memory to extended attribute representation. 792 */ 793 int 794 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl, 795 void *buffer, size_t size) 796 { 797 struct posix_acl_xattr_header *ext_acl = buffer; 798 struct posix_acl_xattr_entry *ext_entry; 799 int real_size, n; 800 801 real_size = posix_acl_xattr_size(acl->a_count); 802 if (!buffer) 803 return real_size; 804 if (real_size > size) 805 return -ERANGE; 806 807 ext_entry = (void *)(ext_acl + 1); 808 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); 809 810 for (n=0; n < acl->a_count; n++, ext_entry++) { 811 const struct posix_acl_entry *acl_e = &acl->a_entries[n]; 812 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); 813 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); 814 switch(acl_e->e_tag) { 815 case ACL_USER: 816 ext_entry->e_id = 817 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid)); 818 break; 819 case ACL_GROUP: 820 ext_entry->e_id = 821 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid)); 822 break; 823 default: 824 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); 825 break; 826 } 827 } 828 return real_size; 829 } 830 EXPORT_SYMBOL (posix_acl_to_xattr); 831 832 static int 833 posix_acl_xattr_get(const struct xattr_handler *handler, 834 struct dentry *unused, struct inode *inode, 835 const char *name, void *value, size_t size) 836 { 837 struct posix_acl *acl; 838 int error; 839 840 if (!IS_POSIXACL(inode)) 841 return -EOPNOTSUPP; 842 if (S_ISLNK(inode->i_mode)) 843 return -EOPNOTSUPP; 844 845 acl = get_acl(inode, handler->flags); 846 if (IS_ERR(acl)) 847 return PTR_ERR(acl); 848 if (acl == NULL) 849 return -ENODATA; 850 851 error = posix_acl_to_xattr(&init_user_ns, acl, value, size); 852 posix_acl_release(acl); 853 854 return error; 855 } 856 857 int 858 set_posix_acl(struct inode *inode, int type, struct posix_acl *acl) 859 { 860 if (!IS_POSIXACL(inode)) 861 return -EOPNOTSUPP; 862 if (!inode->i_op->set_acl) 863 return -EOPNOTSUPP; 864 865 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) 866 return acl ? -EACCES : 0; 867 if (!inode_owner_or_capable(inode)) 868 return -EPERM; 869 870 if (acl) { 871 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl); 872 if (ret) 873 return ret; 874 } 875 return inode->i_op->set_acl(inode, acl, type); 876 } 877 EXPORT_SYMBOL(set_posix_acl); 878 879 static int 880 posix_acl_xattr_set(const struct xattr_handler *handler, 881 struct dentry *unused, struct inode *inode, 882 const char *name, const void *value, 883 size_t size, int flags) 884 { 885 struct posix_acl *acl = NULL; 886 int ret; 887 888 if (value) { 889 acl = posix_acl_from_xattr(&init_user_ns, value, size); 890 if (IS_ERR(acl)) 891 return PTR_ERR(acl); 892 } 893 ret = set_posix_acl(inode, handler->flags, acl); 894 posix_acl_release(acl); 895 return ret; 896 } 897 898 static bool 899 posix_acl_xattr_list(struct dentry *dentry) 900 { 901 return IS_POSIXACL(d_backing_inode(dentry)); 902 } 903 904 const struct xattr_handler posix_acl_access_xattr_handler = { 905 .name = XATTR_NAME_POSIX_ACL_ACCESS, 906 .flags = ACL_TYPE_ACCESS, 907 .list = posix_acl_xattr_list, 908 .get = posix_acl_xattr_get, 909 .set = posix_acl_xattr_set, 910 }; 911 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler); 912 913 const struct xattr_handler posix_acl_default_xattr_handler = { 914 .name = XATTR_NAME_POSIX_ACL_DEFAULT, 915 .flags = ACL_TYPE_DEFAULT, 916 .list = posix_acl_xattr_list, 917 .get = posix_acl_xattr_get, 918 .set = posix_acl_xattr_set, 919 }; 920 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler); 921 922 int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type) 923 { 924 int error; 925 926 if (type == ACL_TYPE_ACCESS) { 927 error = posix_acl_update_mode(inode, 928 &inode->i_mode, &acl); 929 if (error) 930 return error; 931 } 932 933 inode->i_ctime = current_time(inode); 934 set_cached_acl(inode, type, acl); 935 return 0; 936 } 937 938 int simple_acl_create(struct inode *dir, struct inode *inode) 939 { 940 struct posix_acl *default_acl, *acl; 941 int error; 942 943 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); 944 if (error) 945 return error; 946 947 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl); 948 set_cached_acl(inode, ACL_TYPE_ACCESS, acl); 949 950 if (default_acl) 951 posix_acl_release(default_acl); 952 if (acl) 953 posix_acl_release(acl); 954 return 0; 955 } 956