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 user_namespace *mnt_userns, struct inode *inode, 349 const struct posix_acl *acl, int want) 350 { 351 const struct posix_acl_entry *pa, *pe, *mask_obj; 352 int found = 0; 353 kuid_t uid; 354 kgid_t gid; 355 356 want &= MAY_READ | MAY_WRITE | MAY_EXEC; 357 358 FOREACH_ACL_ENTRY(pa, acl, pe) { 359 switch(pa->e_tag) { 360 case ACL_USER_OBJ: 361 /* (May have been checked already) */ 362 uid = i_uid_into_mnt(mnt_userns, inode); 363 if (uid_eq(uid, current_fsuid())) 364 goto check_perm; 365 break; 366 case ACL_USER: 367 uid = kuid_into_mnt(mnt_userns, pa->e_uid); 368 if (uid_eq(uid, current_fsuid())) 369 goto mask; 370 break; 371 case ACL_GROUP_OBJ: 372 gid = i_gid_into_mnt(mnt_userns, inode); 373 if (in_group_p(gid)) { 374 found = 1; 375 if ((pa->e_perm & want) == want) 376 goto mask; 377 } 378 break; 379 case ACL_GROUP: 380 gid = kgid_into_mnt(mnt_userns, pa->e_gid); 381 if (in_group_p(gid)) { 382 found = 1; 383 if ((pa->e_perm & want) == want) 384 goto mask; 385 } 386 break; 387 case ACL_MASK: 388 break; 389 case ACL_OTHER: 390 if (found) 391 return -EACCES; 392 else 393 goto check_perm; 394 default: 395 return -EIO; 396 } 397 } 398 return -EIO; 399 400 mask: 401 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) { 402 if (mask_obj->e_tag == ACL_MASK) { 403 if ((pa->e_perm & mask_obj->e_perm & want) == want) 404 return 0; 405 return -EACCES; 406 } 407 } 408 409 check_perm: 410 if ((pa->e_perm & want) == want) 411 return 0; 412 return -EACCES; 413 } 414 415 /* 416 * Modify acl when creating a new inode. The caller must ensure the acl is 417 * only referenced once. 418 * 419 * mode_p initially must contain the mode parameter to the open() / creat() 420 * system calls. All permissions that are not granted by the acl are removed. 421 * The permissions in the acl are changed to reflect the mode_p parameter. 422 */ 423 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p) 424 { 425 struct posix_acl_entry *pa, *pe; 426 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 427 umode_t mode = *mode_p; 428 int not_equiv = 0; 429 430 /* assert(atomic_read(acl->a_refcount) == 1); */ 431 432 FOREACH_ACL_ENTRY(pa, acl, pe) { 433 switch(pa->e_tag) { 434 case ACL_USER_OBJ: 435 pa->e_perm &= (mode >> 6) | ~S_IRWXO; 436 mode &= (pa->e_perm << 6) | ~S_IRWXU; 437 break; 438 439 case ACL_USER: 440 case ACL_GROUP: 441 not_equiv = 1; 442 break; 443 444 case ACL_GROUP_OBJ: 445 group_obj = pa; 446 break; 447 448 case ACL_OTHER: 449 pa->e_perm &= mode | ~S_IRWXO; 450 mode &= pa->e_perm | ~S_IRWXO; 451 break; 452 453 case ACL_MASK: 454 mask_obj = pa; 455 not_equiv = 1; 456 break; 457 458 default: 459 return -EIO; 460 } 461 } 462 463 if (mask_obj) { 464 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 465 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG; 466 } else { 467 if (!group_obj) 468 return -EIO; 469 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 470 mode &= (group_obj->e_perm << 3) | ~S_IRWXG; 471 } 472 473 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 474 return not_equiv; 475 } 476 477 /* 478 * Modify the ACL for the chmod syscall. 479 */ 480 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode) 481 { 482 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 483 struct posix_acl_entry *pa, *pe; 484 485 /* assert(atomic_read(acl->a_refcount) == 1); */ 486 487 FOREACH_ACL_ENTRY(pa, acl, pe) { 488 switch(pa->e_tag) { 489 case ACL_USER_OBJ: 490 pa->e_perm = (mode & S_IRWXU) >> 6; 491 break; 492 493 case ACL_USER: 494 case ACL_GROUP: 495 break; 496 497 case ACL_GROUP_OBJ: 498 group_obj = pa; 499 break; 500 501 case ACL_MASK: 502 mask_obj = pa; 503 break; 504 505 case ACL_OTHER: 506 pa->e_perm = (mode & S_IRWXO); 507 break; 508 509 default: 510 return -EIO; 511 } 512 } 513 514 if (mask_obj) { 515 mask_obj->e_perm = (mode & S_IRWXG) >> 3; 516 } else { 517 if (!group_obj) 518 return -EIO; 519 group_obj->e_perm = (mode & S_IRWXG) >> 3; 520 } 521 522 return 0; 523 } 524 525 int 526 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p) 527 { 528 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 529 int err = -ENOMEM; 530 if (clone) { 531 err = posix_acl_create_masq(clone, mode_p); 532 if (err < 0) { 533 posix_acl_release(clone); 534 clone = NULL; 535 } 536 } 537 posix_acl_release(*acl); 538 *acl = clone; 539 return err; 540 } 541 EXPORT_SYMBOL(__posix_acl_create); 542 543 int 544 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode) 545 { 546 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 547 int err = -ENOMEM; 548 if (clone) { 549 err = __posix_acl_chmod_masq(clone, mode); 550 if (err) { 551 posix_acl_release(clone); 552 clone = NULL; 553 } 554 } 555 posix_acl_release(*acl); 556 *acl = clone; 557 return err; 558 } 559 EXPORT_SYMBOL(__posix_acl_chmod); 560 561 /** 562 * posix_acl_chmod - chmod a posix acl 563 * 564 * @mnt_userns: user namespace of the mount @inode was found from 565 * @inode: inode to check permissions on 566 * @mode: the new mode of @inode 567 * 568 * If the inode has been found through an idmapped mount the user namespace of 569 * the vfsmount must be passed through @mnt_userns. This function will then 570 * take care to map the inode according to @mnt_userns before checking 571 * permissions. On non-idmapped mounts or if permission checking is to be 572 * performed on the raw inode simply passs init_user_ns. 573 */ 574 int 575 posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode, 576 umode_t mode) 577 { 578 struct posix_acl *acl; 579 int ret = 0; 580 581 if (!IS_POSIXACL(inode)) 582 return 0; 583 if (!inode->i_op->set_acl) 584 return -EOPNOTSUPP; 585 586 acl = get_acl(inode, ACL_TYPE_ACCESS); 587 if (IS_ERR_OR_NULL(acl)) { 588 if (acl == ERR_PTR(-EOPNOTSUPP)) 589 return 0; 590 return PTR_ERR(acl); 591 } 592 593 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode); 594 if (ret) 595 return ret; 596 ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS); 597 posix_acl_release(acl); 598 return ret; 599 } 600 EXPORT_SYMBOL(posix_acl_chmod); 601 602 int 603 posix_acl_create(struct inode *dir, umode_t *mode, 604 struct posix_acl **default_acl, struct posix_acl **acl) 605 { 606 struct posix_acl *p; 607 struct posix_acl *clone; 608 int ret; 609 610 *acl = NULL; 611 *default_acl = NULL; 612 613 if (S_ISLNK(*mode) || !IS_POSIXACL(dir)) 614 return 0; 615 616 p = get_acl(dir, ACL_TYPE_DEFAULT); 617 if (!p || p == ERR_PTR(-EOPNOTSUPP)) { 618 *mode &= ~current_umask(); 619 return 0; 620 } 621 if (IS_ERR(p)) 622 return PTR_ERR(p); 623 624 ret = -ENOMEM; 625 clone = posix_acl_clone(p, GFP_NOFS); 626 if (!clone) 627 goto err_release; 628 629 ret = posix_acl_create_masq(clone, mode); 630 if (ret < 0) 631 goto err_release_clone; 632 633 if (ret == 0) 634 posix_acl_release(clone); 635 else 636 *acl = clone; 637 638 if (!S_ISDIR(*mode)) 639 posix_acl_release(p); 640 else 641 *default_acl = p; 642 643 return 0; 644 645 err_release_clone: 646 posix_acl_release(clone); 647 err_release: 648 posix_acl_release(p); 649 return ret; 650 } 651 EXPORT_SYMBOL_GPL(posix_acl_create); 652 653 /** 654 * posix_acl_update_mode - update mode in set_acl 655 * @mnt_userns: user namespace of the mount @inode was found from 656 * @inode: target inode 657 * @mode_p: mode (pointer) for update 658 * @acl: acl pointer 659 * 660 * Update the file mode when setting an ACL: compute the new file permission 661 * bits based on the ACL. In addition, if the ACL is equivalent to the new 662 * file mode, set *@acl to NULL to indicate that no ACL should be set. 663 * 664 * As with chmod, clear the setgid bit if the caller is not in the owning group 665 * or capable of CAP_FSETID (see inode_change_ok). 666 * 667 * If the inode has been found through an idmapped mount the user namespace of 668 * the vfsmount must be passed through @mnt_userns. This function will then 669 * take care to map the inode according to @mnt_userns before checking 670 * permissions. On non-idmapped mounts or if permission checking is to be 671 * performed on the raw inode simply passs init_user_ns. 672 * 673 * Called from set_acl inode operations. 674 */ 675 int posix_acl_update_mode(struct user_namespace *mnt_userns, 676 struct inode *inode, umode_t *mode_p, 677 struct posix_acl **acl) 678 { 679 umode_t mode = inode->i_mode; 680 int error; 681 682 error = posix_acl_equiv_mode(*acl, &mode); 683 if (error < 0) 684 return error; 685 if (error == 0) 686 *acl = NULL; 687 if (!in_group_p(i_gid_into_mnt(mnt_userns, inode)) && 688 !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID)) 689 mode &= ~S_ISGID; 690 *mode_p = mode; 691 return 0; 692 } 693 EXPORT_SYMBOL(posix_acl_update_mode); 694 695 /* 696 * Fix up the uids and gids in posix acl extended attributes in place. 697 */ 698 static void posix_acl_fix_xattr_userns( 699 struct user_namespace *to, struct user_namespace *from, 700 struct user_namespace *mnt_userns, 701 void *value, size_t size, bool from_user) 702 { 703 struct posix_acl_xattr_header *header = value; 704 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; 705 int count; 706 kuid_t uid; 707 kgid_t gid; 708 709 if (!value) 710 return; 711 if (size < sizeof(struct posix_acl_xattr_header)) 712 return; 713 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 714 return; 715 716 count = posix_acl_xattr_count(size); 717 if (count < 0) 718 return; 719 if (count == 0) 720 return; 721 722 for (end = entry + count; entry != end; entry++) { 723 switch(le16_to_cpu(entry->e_tag)) { 724 case ACL_USER: 725 uid = make_kuid(from, le32_to_cpu(entry->e_id)); 726 if (from_user) 727 uid = kuid_from_mnt(mnt_userns, uid); 728 else 729 uid = kuid_into_mnt(mnt_userns, uid); 730 entry->e_id = cpu_to_le32(from_kuid(to, uid)); 731 break; 732 case ACL_GROUP: 733 gid = make_kgid(from, le32_to_cpu(entry->e_id)); 734 if (from_user) 735 gid = kgid_from_mnt(mnt_userns, gid); 736 else 737 gid = kgid_into_mnt(mnt_userns, gid); 738 entry->e_id = cpu_to_le32(from_kgid(to, gid)); 739 break; 740 default: 741 break; 742 } 743 } 744 } 745 746 void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns, 747 void *value, size_t size) 748 { 749 struct user_namespace *user_ns = current_user_ns(); 750 if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns)) 751 return; 752 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, mnt_userns, value, 753 size, true); 754 } 755 756 void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns, 757 void *value, size_t size) 758 { 759 struct user_namespace *user_ns = current_user_ns(); 760 if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns)) 761 return; 762 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, mnt_userns, value, 763 size, false); 764 } 765 766 /* 767 * Convert from extended attribute to in-memory representation. 768 */ 769 struct posix_acl * 770 posix_acl_from_xattr(struct user_namespace *user_ns, 771 const void *value, size_t size) 772 { 773 const struct posix_acl_xattr_header *header = value; 774 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end; 775 int count; 776 struct posix_acl *acl; 777 struct posix_acl_entry *acl_e; 778 779 if (!value) 780 return NULL; 781 if (size < sizeof(struct posix_acl_xattr_header)) 782 return ERR_PTR(-EINVAL); 783 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 784 return ERR_PTR(-EOPNOTSUPP); 785 786 count = posix_acl_xattr_count(size); 787 if (count < 0) 788 return ERR_PTR(-EINVAL); 789 if (count == 0) 790 return NULL; 791 792 acl = posix_acl_alloc(count, GFP_NOFS); 793 if (!acl) 794 return ERR_PTR(-ENOMEM); 795 acl_e = acl->a_entries; 796 797 for (end = entry + count; entry != end; acl_e++, entry++) { 798 acl_e->e_tag = le16_to_cpu(entry->e_tag); 799 acl_e->e_perm = le16_to_cpu(entry->e_perm); 800 801 switch(acl_e->e_tag) { 802 case ACL_USER_OBJ: 803 case ACL_GROUP_OBJ: 804 case ACL_MASK: 805 case ACL_OTHER: 806 break; 807 808 case ACL_USER: 809 acl_e->e_uid = 810 make_kuid(user_ns, 811 le32_to_cpu(entry->e_id)); 812 if (!uid_valid(acl_e->e_uid)) 813 goto fail; 814 break; 815 case ACL_GROUP: 816 acl_e->e_gid = 817 make_kgid(user_ns, 818 le32_to_cpu(entry->e_id)); 819 if (!gid_valid(acl_e->e_gid)) 820 goto fail; 821 break; 822 823 default: 824 goto fail; 825 } 826 } 827 return acl; 828 829 fail: 830 posix_acl_release(acl); 831 return ERR_PTR(-EINVAL); 832 } 833 EXPORT_SYMBOL (posix_acl_from_xattr); 834 835 /* 836 * Convert from in-memory to extended attribute representation. 837 */ 838 int 839 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl, 840 void *buffer, size_t size) 841 { 842 struct posix_acl_xattr_header *ext_acl = buffer; 843 struct posix_acl_xattr_entry *ext_entry; 844 int real_size, n; 845 846 real_size = posix_acl_xattr_size(acl->a_count); 847 if (!buffer) 848 return real_size; 849 if (real_size > size) 850 return -ERANGE; 851 852 ext_entry = (void *)(ext_acl + 1); 853 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); 854 855 for (n=0; n < acl->a_count; n++, ext_entry++) { 856 const struct posix_acl_entry *acl_e = &acl->a_entries[n]; 857 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); 858 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); 859 switch(acl_e->e_tag) { 860 case ACL_USER: 861 ext_entry->e_id = 862 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid)); 863 break; 864 case ACL_GROUP: 865 ext_entry->e_id = 866 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid)); 867 break; 868 default: 869 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); 870 break; 871 } 872 } 873 return real_size; 874 } 875 EXPORT_SYMBOL (posix_acl_to_xattr); 876 877 static int 878 posix_acl_xattr_get(const struct xattr_handler *handler, 879 struct dentry *unused, struct inode *inode, 880 const char *name, void *value, size_t size) 881 { 882 struct posix_acl *acl; 883 int error; 884 885 if (!IS_POSIXACL(inode)) 886 return -EOPNOTSUPP; 887 if (S_ISLNK(inode->i_mode)) 888 return -EOPNOTSUPP; 889 890 acl = get_acl(inode, handler->flags); 891 if (IS_ERR(acl)) 892 return PTR_ERR(acl); 893 if (acl == NULL) 894 return -ENODATA; 895 896 error = posix_acl_to_xattr(&init_user_ns, acl, value, size); 897 posix_acl_release(acl); 898 899 return error; 900 } 901 902 int 903 set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode, 904 int type, struct posix_acl *acl) 905 { 906 if (!IS_POSIXACL(inode)) 907 return -EOPNOTSUPP; 908 if (!inode->i_op->set_acl) 909 return -EOPNOTSUPP; 910 911 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) 912 return acl ? -EACCES : 0; 913 if (!inode_owner_or_capable(mnt_userns, inode)) 914 return -EPERM; 915 916 if (acl) { 917 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl); 918 if (ret) 919 return ret; 920 } 921 return inode->i_op->set_acl(mnt_userns, inode, acl, type); 922 } 923 EXPORT_SYMBOL(set_posix_acl); 924 925 static int 926 posix_acl_xattr_set(const struct xattr_handler *handler, 927 struct user_namespace *mnt_userns, 928 struct dentry *unused, struct inode *inode, 929 const char *name, const void *value, size_t size, 930 int flags) 931 { 932 struct posix_acl *acl = NULL; 933 int ret; 934 935 if (value) { 936 acl = posix_acl_from_xattr(&init_user_ns, value, size); 937 if (IS_ERR(acl)) 938 return PTR_ERR(acl); 939 } 940 ret = set_posix_acl(mnt_userns, inode, handler->flags, acl); 941 posix_acl_release(acl); 942 return ret; 943 } 944 945 static bool 946 posix_acl_xattr_list(struct dentry *dentry) 947 { 948 return IS_POSIXACL(d_backing_inode(dentry)); 949 } 950 951 const struct xattr_handler posix_acl_access_xattr_handler = { 952 .name = XATTR_NAME_POSIX_ACL_ACCESS, 953 .flags = ACL_TYPE_ACCESS, 954 .list = posix_acl_xattr_list, 955 .get = posix_acl_xattr_get, 956 .set = posix_acl_xattr_set, 957 }; 958 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler); 959 960 const struct xattr_handler posix_acl_default_xattr_handler = { 961 .name = XATTR_NAME_POSIX_ACL_DEFAULT, 962 .flags = ACL_TYPE_DEFAULT, 963 .list = posix_acl_xattr_list, 964 .get = posix_acl_xattr_get, 965 .set = posix_acl_xattr_set, 966 }; 967 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler); 968 969 int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode, 970 struct posix_acl *acl, int type) 971 { 972 int error; 973 974 if (type == ACL_TYPE_ACCESS) { 975 error = posix_acl_update_mode(mnt_userns, inode, 976 &inode->i_mode, &acl); 977 if (error) 978 return error; 979 } 980 981 inode->i_ctime = current_time(inode); 982 set_cached_acl(inode, type, acl); 983 return 0; 984 } 985 986 int simple_acl_create(struct inode *dir, struct inode *inode) 987 { 988 struct posix_acl *default_acl, *acl; 989 int error; 990 991 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); 992 if (error) 993 return error; 994 995 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl); 996 set_cached_acl(inode, ACL_TYPE_ACCESS, acl); 997 998 if (default_acl) 999 posix_acl_release(default_acl); 1000 if (acl) 1001 posix_acl_release(acl); 1002 return 0; 1003 } 1004