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posix_acl.c
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linux-6.19.14/fs/posix_acl.c
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#include <linux/namei.h> 26#include <linux/mnt_idmapping.h> 27#include <linux/iversion.h> 28#include <linux/security.h> 29#include <linux/fsnotify.h> 30#include <linux/filelock.h> 31 32#include "internal.h" 33 34static struct posix_acl **acl_by_type(struct inode *inode, int type) 35{ 36 switch (type) { 37 case ACL_TYPE_ACCESS: 38 return &inode->i_acl; 39 case ACL_TYPE_DEFAULT: 40 return &inode->i_default_acl; 41 default: 42 BUG(); 43 } 44} 45 46struct posix_acl *get_cached_acl(struct inode *inode, int type) 47{ 48 struct posix_acl **p = acl_by_type(inode, type); 49 struct posix_acl *acl; 50 51 for (;;) { 52 rcu_read_lock(); 53 acl = rcu_dereference(*p); 54 if (!acl || is_uncached_acl(acl) || 55 refcount_inc_not_zero(&acl->a_refcount)) 56 break; 57 rcu_read_unlock(); 58 cpu_relax(); 59 } 60 rcu_read_unlock(); 61 return acl; 62} 63EXPORT_SYMBOL(get_cached_acl); 64 65struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type) 66{ 67 struct posix_acl *acl = rcu_dereference(*acl_by_type(inode, type)); 68 69 if (acl == ACL_DONT_CACHE) { 70 struct posix_acl *ret; 71 72 ret = inode->i_op->get_inode_acl(inode, type, LOOKUP_RCU); 73 if (!IS_ERR(ret)) 74 acl = ret; 75 } 76 77 return acl; 78} 79EXPORT_SYMBOL(get_cached_acl_rcu); 80 81void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl) 82{ 83 struct posix_acl **p = acl_by_type(inode, type); 84 struct posix_acl *old; 85 86 old = xchg(p, posix_acl_dup(acl)); 87 if (!is_uncached_acl(old)) 88 posix_acl_release(old); 89} 90EXPORT_SYMBOL(set_cached_acl); 91 92static void __forget_cached_acl(struct posix_acl **p) 93{ 94 struct posix_acl *old; 95 96 old = xchg(p, ACL_NOT_CACHED); 97 if (!is_uncached_acl(old)) 98 posix_acl_release(old); 99} 100 101void forget_cached_acl(struct inode *inode, int type) 102{ 103 __forget_cached_acl(acl_by_type(inode, type)); 104} 105EXPORT_SYMBOL(forget_cached_acl); 106 107void forget_all_cached_acls(struct inode *inode) 108{ 109 __forget_cached_acl(&inode->i_acl); 110 __forget_cached_acl(&inode->i_default_acl); 111} 112EXPORT_SYMBOL(forget_all_cached_acls); 113 114static struct posix_acl *__get_acl(struct mnt_idmap *idmap, 115 struct dentry *dentry, struct inode *inode, 116 int type) 117{ 118 struct posix_acl *sentinel; 119 struct posix_acl **p; 120 struct posix_acl *acl; 121 122 /* 123 * The sentinel is used to detect when another operation like 124 * set_cached_acl() or forget_cached_acl() races with get_inode_acl(). 125 * It is guaranteed that is_uncached_acl(sentinel) is true. 126 */ 127 128 acl = get_cached_acl(inode, type); 129 if (!is_uncached_acl(acl)) 130 return acl; 131 132 if (!IS_POSIXACL(inode)) 133 return NULL; 134 135 sentinel = uncached_acl_sentinel(current); 136 p = acl_by_type(inode, type); 137 138 /* 139 * If the ACL isn't being read yet, set our sentinel. Otherwise, the 140 * current value of the ACL will not be ACL_NOT_CACHED and so our own 141 * sentinel will not be set; another task will update the cache. We 142 * could wait for that other task to complete its job, but it's easier 143 * to just call ->get_inode_acl to fetch the ACL ourself. (This is 144 * going to be an unlikely race.) 145 */ 146 cmpxchg(p, ACL_NOT_CACHED, sentinel); 147 148 /* 149 * Normally, the ACL returned by ->get{_inode}_acl will be cached. 150 * A filesystem can prevent that by calling 151 * forget_cached_acl(inode, type) in ->get{_inode}_acl. 152 * 153 * If the filesystem doesn't have a get{_inode}_ acl() function at all, 154 * we'll just create the negative cache entry. 155 */ 156 if (dentry && inode->i_op->get_acl) { 157 acl = inode->i_op->get_acl(idmap, dentry, type); 158 } else if (inode->i_op->get_inode_acl) { 159 acl = inode->i_op->get_inode_acl(inode, type, false); 160 } else { 161 set_cached_acl(inode, type, NULL); 162 return NULL; 163 } 164 if (IS_ERR(acl)) { 165 /* 166 * Remove our sentinel so that we don't block future attempts 167 * to cache the ACL. 168 */ 169 cmpxchg(p, sentinel, ACL_NOT_CACHED); 170 return acl; 171 } 172 173 /* 174 * Cache the result, but only if our sentinel is still in place. 175 */ 176 posix_acl_dup(acl); 177 if (unlikely(!try_cmpxchg(p, &sentinel, acl))) 178 posix_acl_release(acl); 179 return acl; 180} 181 182struct posix_acl *get_inode_acl(struct inode *inode, int type) 183{ 184 return __get_acl(&nop_mnt_idmap, NULL, inode, type); 185} 186EXPORT_SYMBOL(get_inode_acl); 187 188/* 189 * Init a fresh posix_acl 190 */ 191void 192posix_acl_init(struct posix_acl *acl, int count) 193{ 194 refcount_set(&acl->a_refcount, 1); 195 acl->a_count = count; 196} 197EXPORT_SYMBOL(posix_acl_init); 198 199/* 200 * Allocate a new ACL with the specified number of entries. 201 */ 202struct posix_acl * 203posix_acl_alloc(unsigned int count, gfp_t flags) 204{ 205 struct posix_acl *acl; 206 207 acl = kmalloc(struct_size(acl, a_entries, count), flags); 208 if (acl) 209 posix_acl_init(acl, count); 210 return acl; 211} 212EXPORT_SYMBOL(posix_acl_alloc); 213 214/* 215 * Clone an ACL. 216 */ 217struct posix_acl * 218posix_acl_clone(const struct posix_acl *acl, gfp_t flags) 219{ 220 struct posix_acl *clone = NULL; 221 222 if (acl) { 223 clone = kmemdup(acl, struct_size(acl, a_entries, acl->a_count), 224 flags); 225 if (clone) 226 refcount_set(&clone->a_refcount, 1); 227 } 228 return clone; 229} 230EXPORT_SYMBOL_GPL(posix_acl_clone); 231 232/* 233 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise. 234 */ 235int 236posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl) 237{ 238 const struct posix_acl_entry *pa, *pe; 239 int state = ACL_USER_OBJ; 240 int needs_mask = 0; 241 242 FOREACH_ACL_ENTRY(pa, acl, pe) { 243 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE)) 244 return -EINVAL; 245 switch (pa->e_tag) { 246 case ACL_USER_OBJ: 247 if (state == ACL_USER_OBJ) { 248 state = ACL_USER; 249 break; 250 } 251 return -EINVAL; 252 253 case ACL_USER: 254 if (state != ACL_USER) 255 return -EINVAL; 256 if (!kuid_has_mapping(user_ns, pa->e_uid)) 257 return -EINVAL; 258 needs_mask = 1; 259 break; 260 261 case ACL_GROUP_OBJ: 262 if (state == ACL_USER) { 263 state = ACL_GROUP; 264 break; 265 } 266 return -EINVAL; 267 268 case ACL_GROUP: 269 if (state != ACL_GROUP) 270 return -EINVAL; 271 if (!kgid_has_mapping(user_ns, pa->e_gid)) 272 return -EINVAL; 273 needs_mask = 1; 274 break; 275 276 case ACL_MASK: 277 if (state != ACL_GROUP) 278 return -EINVAL; 279 state = ACL_OTHER; 280 break; 281 282 case ACL_OTHER: 283 if (state == ACL_OTHER || 284 (state == ACL_GROUP && !needs_mask)) { 285 state = 0; 286 break; 287 } 288 return -EINVAL; 289 290 default: 291 return -EINVAL; 292 } 293 } 294 if (state == 0) 295 return 0; 296 return -EINVAL; 297} 298EXPORT_SYMBOL(posix_acl_valid); 299 300/* 301 * Returns 0 if the acl can be exactly represented in the traditional 302 * file mode permission bits, or else 1. Returns -E... on error. 303 */ 304int 305posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p) 306{ 307 const struct posix_acl_entry *pa, *pe; 308 umode_t mode = 0; 309 int not_equiv = 0; 310 311 /* 312 * A null ACL can always be presented as mode bits. 313 */ 314 if (!acl) 315 return 0; 316 317 FOREACH_ACL_ENTRY(pa, acl, pe) { 318 switch (pa->e_tag) { 319 case ACL_USER_OBJ: 320 mode |= (pa->e_perm & S_IRWXO) << 6; 321 break; 322 case ACL_GROUP_OBJ: 323 mode |= (pa->e_perm & S_IRWXO) << 3; 324 break; 325 case ACL_OTHER: 326 mode |= pa->e_perm & S_IRWXO; 327 break; 328 case ACL_MASK: 329 mode = (mode & ~S_IRWXG) | 330 ((pa->e_perm & S_IRWXO) << 3); 331 not_equiv = 1; 332 break; 333 case ACL_USER: 334 case ACL_GROUP: 335 not_equiv = 1; 336 break; 337 default: 338 return -EINVAL; 339 } 340 } 341 if (mode_p) 342 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 343 return not_equiv; 344} 345EXPORT_SYMBOL(posix_acl_equiv_mode); 346 347/* 348 * Create an ACL representing the file mode permission bits of an inode. 349 */ 350struct posix_acl * 351posix_acl_from_mode(umode_t mode, gfp_t flags) 352{ 353 struct posix_acl *acl = posix_acl_alloc(3, flags); 354 if (!acl) 355 return ERR_PTR(-ENOMEM); 356 357 acl->a_entries[0].e_tag = ACL_USER_OBJ; 358 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6; 359 360 acl->a_entries[1].e_tag = ACL_GROUP_OBJ; 361 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3; 362 363 acl->a_entries[2].e_tag = ACL_OTHER; 364 acl->a_entries[2].e_perm = (mode & S_IRWXO); 365 return acl; 366} 367EXPORT_SYMBOL(posix_acl_from_mode); 368 369/* 370 * Return 0 if current is granted want access to the inode 371 * by the acl. Returns -E... otherwise. 372 */ 373int 374posix_acl_permission(struct mnt_idmap *idmap, struct inode *inode, 375 const struct posix_acl *acl, int want) 376{ 377 const struct posix_acl_entry *pa, *pe, *mask_obj; 378 struct user_namespace *fs_userns = i_user_ns(inode); 379 int found = 0; 380 vfsuid_t vfsuid; 381 vfsgid_t vfsgid; 382 383 want &= MAY_READ | MAY_WRITE | MAY_EXEC; 384 385 FOREACH_ACL_ENTRY(pa, acl, pe) { 386 switch(pa->e_tag) { 387 case ACL_USER_OBJ: 388 /* (May have been checked already) */ 389 vfsuid = i_uid_into_vfsuid(idmap, inode); 390 if (vfsuid_eq_kuid(vfsuid, current_fsuid())) 391 goto check_perm; 392 break; 393 case ACL_USER: 394 vfsuid = make_vfsuid(idmap, fs_userns, 395 pa->e_uid); 396 if (vfsuid_eq_kuid(vfsuid, current_fsuid())) 397 goto mask; 398 break; 399 case ACL_GROUP_OBJ: 400 vfsgid = i_gid_into_vfsgid(idmap, inode); 401 if (vfsgid_in_group_p(vfsgid)) { 402 found = 1; 403 if ((pa->e_perm & want) == want) 404 goto mask; 405 } 406 break; 407 case ACL_GROUP: 408 vfsgid = make_vfsgid(idmap, fs_userns, 409 pa->e_gid); 410 if (vfsgid_in_group_p(vfsgid)) { 411 found = 1; 412 if ((pa->e_perm & want) == want) 413 goto mask; 414 } 415 break; 416 case ACL_MASK: 417 break; 418 case ACL_OTHER: 419 if (found) 420 return -EACCES; 421 else 422 goto check_perm; 423 default: 424 return -EIO; 425 } 426 } 427 return -EIO; 428 429mask: 430 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) { 431 if (mask_obj->e_tag == ACL_MASK) { 432 if ((pa->e_perm & mask_obj->e_perm & want) == want) 433 return 0; 434 return -EACCES; 435 } 436 } 437 438check_perm: 439 if ((pa->e_perm & want) == want) 440 return 0; 441 return -EACCES; 442} 443 444/* 445 * Modify acl when creating a new inode. The caller must ensure the acl is 446 * only referenced once. 447 * 448 * mode_p initially must contain the mode parameter to the open() / creat() 449 * system calls. All permissions that are not granted by the acl are removed. 450 * The permissions in the acl are changed to reflect the mode_p parameter. 451 */ 452static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p) 453{ 454 struct posix_acl_entry *pa, *pe; 455 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 456 umode_t mode = *mode_p; 457 int not_equiv = 0; 458 459 /* assert(atomic_read(acl->a_refcount) == 1); */ 460 461 FOREACH_ACL_ENTRY(pa, acl, pe) { 462 switch(pa->e_tag) { 463 case ACL_USER_OBJ: 464 pa->e_perm &= (mode >> 6) | ~S_IRWXO; 465 mode &= (pa->e_perm << 6) | ~S_IRWXU; 466 break; 467 468 case ACL_USER: 469 case ACL_GROUP: 470 not_equiv = 1; 471 break; 472 473 case ACL_GROUP_OBJ: 474 group_obj = pa; 475 break; 476 477 case ACL_OTHER: 478 pa->e_perm &= mode | ~S_IRWXO; 479 mode &= pa->e_perm | ~S_IRWXO; 480 break; 481 482 case ACL_MASK: 483 mask_obj = pa; 484 not_equiv = 1; 485 break; 486 487 default: 488 return -EIO; 489 } 490 } 491 492 if (mask_obj) { 493 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 494 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG; 495 } else { 496 if (!group_obj) 497 return -EIO; 498 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 499 mode &= (group_obj->e_perm << 3) | ~S_IRWXG; 500 } 501 502 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 503 return not_equiv; 504} 505 506/* 507 * Modify the ACL for the chmod syscall. 508 */ 509static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode) 510{ 511 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 512 struct posix_acl_entry *pa, *pe; 513 514 /* assert(atomic_read(acl->a_refcount) == 1); */ 515 516 FOREACH_ACL_ENTRY(pa, acl, pe) { 517 switch(pa->e_tag) { 518 case ACL_USER_OBJ: 519 pa->e_perm = (mode & S_IRWXU) >> 6; 520 break; 521 522 case ACL_USER: 523 case ACL_GROUP: 524 break; 525 526 case ACL_GROUP_OBJ: 527 group_obj = pa; 528 break; 529 530 case ACL_MASK: 531 mask_obj = pa; 532 break; 533 534 case ACL_OTHER: 535 pa->e_perm = (mode & S_IRWXO); 536 break; 537 538 default: 539 return -EIO; 540 } 541 } 542 543 if (mask_obj) { 544 mask_obj->e_perm = (mode & S_IRWXG) >> 3; 545 } else { 546 if (!group_obj) 547 return -EIO; 548 group_obj->e_perm = (mode & S_IRWXG) >> 3; 549 } 550 551 return 0; 552} 553 554int 555__posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p) 556{ 557 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 558 int err = -ENOMEM; 559 if (clone) { 560 err = posix_acl_create_masq(clone, mode_p); 561 if (err < 0) { 562 posix_acl_release(clone); 563 clone = NULL; 564 } 565 } 566 posix_acl_release(*acl); 567 *acl = clone; 568 return err; 569} 570EXPORT_SYMBOL(__posix_acl_create); 571 572int 573__posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode) 574{ 575 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 576 int err = -ENOMEM; 577 if (clone) { 578 err = __posix_acl_chmod_masq(clone, mode); 579 if (err) { 580 posix_acl_release(clone); 581 clone = NULL; 582 } 583 } 584 posix_acl_release(*acl); 585 *acl = clone; 586 return err; 587} 588EXPORT_SYMBOL(__posix_acl_chmod); 589 590/** 591 * posix_acl_chmod - chmod a posix acl 592 * 593 * @idmap: idmap of the mount @inode was found from 594 * @dentry: dentry to check permissions on 595 * @mode: the new mode of @inode 596 * 597 * If the dentry has been found through an idmapped mount the idmap of 598 * the vfsmount must be passed through @idmap. This function will then 599 * take care to map the inode according to @idmap before checking 600 * permissions. On non-idmapped mounts or if permission checking is to be 601 * performed on the raw inode simply pass @nop_mnt_idmap. 602 */ 603int 604 posix_acl_chmod(struct mnt_idmap *idmap, struct dentry *dentry, 605 umode_t mode) 606{ 607 struct inode *inode = d_inode(dentry); 608 struct posix_acl *acl; 609 int ret = 0; 610 611 if (!IS_POSIXACL(inode)) 612 return 0; 613 if (!inode->i_op->set_acl) 614 return -EOPNOTSUPP; 615 616 acl = get_inode_acl(inode, ACL_TYPE_ACCESS); 617 if (IS_ERR_OR_NULL(acl)) { 618 if (acl == ERR_PTR(-EOPNOTSUPP)) 619 return 0; 620 return PTR_ERR(acl); 621 } 622 623 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode); 624 if (ret) 625 return ret; 626 ret = inode->i_op->set_acl(idmap, dentry, acl, ACL_TYPE_ACCESS); 627 posix_acl_release(acl); 628 return ret; 629} 630EXPORT_SYMBOL(posix_acl_chmod); 631 632int 633posix_acl_create(struct inode *dir, umode_t *mode, 634 struct posix_acl **default_acl, struct posix_acl **acl) 635{ 636 struct posix_acl *p; 637 struct posix_acl *clone; 638 int ret; 639 640 *acl = NULL; 641 *default_acl = NULL; 642 643 if (S_ISLNK(*mode) || !IS_POSIXACL(dir)) 644 return 0; 645 646 p = get_inode_acl(dir, ACL_TYPE_DEFAULT); 647 if (!p || p == ERR_PTR(-EOPNOTSUPP)) { 648 *mode &= ~current_umask(); 649 return 0; 650 } 651 if (IS_ERR(p)) 652 return PTR_ERR(p); 653 654 ret = -ENOMEM; 655 clone = posix_acl_clone(p, GFP_NOFS); 656 if (!clone) 657 goto err_release; 658 659 ret = posix_acl_create_masq(clone, mode); 660 if (ret < 0) 661 goto err_release_clone; 662 663 if (ret == 0) 664 posix_acl_release(clone); 665 else 666 *acl = clone; 667 668 if (!S_ISDIR(*mode)) 669 posix_acl_release(p); 670 else 671 *default_acl = p; 672 673 return 0; 674 675err_release_clone: 676 posix_acl_release(clone); 677err_release: 678 posix_acl_release(p); 679 return ret; 680} 681EXPORT_SYMBOL_GPL(posix_acl_create); 682 683/** 684 * posix_acl_update_mode - update mode in set_acl 685 * @idmap: idmap of the mount @inode was found from 686 * @inode: target inode 687 * @mode_p: mode (pointer) for update 688 * @acl: acl pointer 689 * 690 * Update the file mode when setting an ACL: compute the new file permission 691 * bits based on the ACL. In addition, if the ACL is equivalent to the new 692 * file mode, set *@acl to NULL to indicate that no ACL should be set. 693 * 694 * As with chmod, clear the setgid bit if the caller is not in the owning group 695 * or capable of CAP_FSETID (see inode_change_ok). 696 * 697 * If the inode has been found through an idmapped mount the idmap of 698 * the vfsmount must be passed through @idmap. This function will then 699 * take care to map the inode according to @idmap before checking 700 * permissions. On non-idmapped mounts or if permission checking is to be 701 * performed on the raw inode simply pass @nop_mnt_idmap. 702 * 703 * Called from set_acl inode operations. 704 */ 705int posix_acl_update_mode(struct mnt_idmap *idmap, 706 struct inode *inode, umode_t *mode_p, 707 struct posix_acl **acl) 708{ 709 umode_t mode = inode->i_mode; 710 int error; 711 712 error = posix_acl_equiv_mode(*acl, &mode); 713 if (error < 0) 714 return error; 715 if (error == 0) 716 *acl = NULL; 717 if (!in_group_or_capable(idmap, inode, 718 i_gid_into_vfsgid(idmap, inode))) 719 mode &= ~S_ISGID; 720 *mode_p = mode; 721 return 0; 722} 723EXPORT_SYMBOL(posix_acl_update_mode); 724 725/* 726 * Fix up the uids and gids in posix acl extended attributes in place. 727 */ 728static int posix_acl_fix_xattr_common(const void *value, size_t size) 729{ 730 const struct posix_acl_xattr_header *header = value; 731 int count; 732 733 if (!header) 734 return -EINVAL; 735 if (size < sizeof(struct posix_acl_xattr_header)) 736 return -EINVAL; 737 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 738 return -EOPNOTSUPP; 739 740 count = posix_acl_xattr_count(size); 741 if (count < 0) 742 return -EINVAL; 743 if (count == 0) 744 return 0; 745 746 return count; 747} 748 749/** 750 * posix_acl_from_xattr - convert POSIX ACLs from backing store to VFS format 751 * @userns: the filesystem's idmapping 752 * @value: the uapi representation of POSIX ACLs 753 * @size: the size of @void 754 * 755 * Filesystems that store POSIX ACLs in the unaltered uapi format should use 756 * posix_acl_from_xattr() when reading them from the backing store and 757 * converting them into the struct posix_acl VFS format. The helper is 758 * specifically intended to be called from the acl inode operation. 759 * 760 * The posix_acl_from_xattr() function will map the raw {g,u}id values stored 761 * in ACL_{GROUP,USER} entries into idmapping in @userns. 762 * 763 * Note that posix_acl_from_xattr() does not take idmapped mounts into account. 764 * If it did it calling it from the get acl inode operation would return POSIX 765 * ACLs mapped according to an idmapped mount which would mean that the value 766 * couldn't be cached for the filesystem. Idmapped mounts are taken into 767 * account on the fly during permission checking or right at the VFS - 768 * userspace boundary before reporting them to the user. 769 * 770 * Return: Allocated struct posix_acl on success, NULL for a valid header but 771 * without actual POSIX ACL entries, or ERR_PTR() encoded error code. 772 */ 773struct posix_acl *posix_acl_from_xattr(struct user_namespace *userns, 774 const void *value, size_t size) 775{ 776 const struct posix_acl_xattr_header *header = value; 777 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end; 778 int count; 779 struct posix_acl *acl; 780 struct posix_acl_entry *acl_e; 781 782 count = posix_acl_fix_xattr_common(value, size); 783 if (count < 0) 784 return ERR_PTR(count); 785 if (count == 0) 786 return NULL; 787 788 acl = posix_acl_alloc(count, GFP_NOFS); 789 if (!acl) 790 return ERR_PTR(-ENOMEM); 791 acl_e = acl->a_entries; 792 793 for (end = entry + count; entry != end; acl_e++, entry++) { 794 acl_e->e_tag = le16_to_cpu(entry->e_tag); 795 acl_e->e_perm = le16_to_cpu(entry->e_perm); 796 797 switch(acl_e->e_tag) { 798 case ACL_USER_OBJ: 799 case ACL_GROUP_OBJ: 800 case ACL_MASK: 801 case ACL_OTHER: 802 break; 803 804 case ACL_USER: 805 acl_e->e_uid = make_kuid(userns, 806 le32_to_cpu(entry->e_id)); 807 if (!uid_valid(acl_e->e_uid)) 808 goto fail; 809 break; 810 case ACL_GROUP: 811 acl_e->e_gid = make_kgid(userns, 812 le32_to_cpu(entry->e_id)); 813 if (!gid_valid(acl_e->e_gid)) 814 goto fail; 815 break; 816 817 default: 818 goto fail; 819 } 820 } 821 return acl; 822 823fail: 824 posix_acl_release(acl); 825 return ERR_PTR(-EINVAL); 826} 827EXPORT_SYMBOL (posix_acl_from_xattr); 828 829/* 830 * Convert from in-memory to extended attribute representation. 831 */ 832int 833posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl, 834 void *buffer, size_t size) 835{ 836 struct posix_acl_xattr_header *ext_acl = buffer; 837 struct posix_acl_xattr_entry *ext_entry; 838 int real_size, n; 839 840 real_size = posix_acl_xattr_size(acl->a_count); 841 if (!buffer) 842 return real_size; 843 if (real_size > size) 844 return -ERANGE; 845 846 ext_entry = (void *)(ext_acl + 1); 847 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); 848 849 for (n=0; n < acl->a_count; n++, ext_entry++) { 850 const struct posix_acl_entry *acl_e = &acl->a_entries[n]; 851 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); 852 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); 853 switch(acl_e->e_tag) { 854 case ACL_USER: 855 ext_entry->e_id = 856 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid)); 857 break; 858 case ACL_GROUP: 859 ext_entry->e_id = 860 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid)); 861 break; 862 default: 863 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); 864 break; 865 } 866 } 867 return real_size; 868} 869EXPORT_SYMBOL (posix_acl_to_xattr); 870 871/** 872 * vfs_posix_acl_to_xattr - convert from kernel to userspace representation 873 * @idmap: idmap of the mount 874 * @inode: inode the posix acls are set on 875 * @acl: the posix acls as represented by the vfs 876 * @buffer: the buffer into which to convert @acl 877 * @size: size of @buffer 878 * 879 * This converts @acl from the VFS representation in the filesystem idmapping 880 * to the uapi form reportable to userspace. And mount and caller idmappings 881 * are handled appropriately. 882 * 883 * Return: On success, the size of the stored uapi posix acls, on error a 884 * negative errno. 885 */ 886static ssize_t vfs_posix_acl_to_xattr(struct mnt_idmap *idmap, 887 struct inode *inode, 888 const struct posix_acl *acl, void *buffer, 889 size_t size) 890 891{ 892 struct posix_acl_xattr_header *ext_acl = buffer; 893 struct posix_acl_xattr_entry *ext_entry; 894 struct user_namespace *fs_userns, *caller_userns; 895 ssize_t real_size, n; 896 vfsuid_t vfsuid; 897 vfsgid_t vfsgid; 898 899 real_size = posix_acl_xattr_size(acl->a_count); 900 if (!buffer) 901 return real_size; 902 if (real_size > size) 903 return -ERANGE; 904 905 ext_entry = (void *)(ext_acl + 1); 906 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); 907 908 fs_userns = i_user_ns(inode); 909 caller_userns = current_user_ns(); 910 for (n=0; n < acl->a_count; n++, ext_entry++) { 911 const struct posix_acl_entry *acl_e = &acl->a_entries[n]; 912 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); 913 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); 914 switch(acl_e->e_tag) { 915 case ACL_USER: 916 vfsuid = make_vfsuid(idmap, fs_userns, acl_e->e_uid); 917 ext_entry->e_id = cpu_to_le32(from_kuid( 918 caller_userns, vfsuid_into_kuid(vfsuid))); 919 break; 920 case ACL_GROUP: 921 vfsgid = make_vfsgid(idmap, fs_userns, acl_e->e_gid); 922 ext_entry->e_id = cpu_to_le32(from_kgid( 923 caller_userns, vfsgid_into_kgid(vfsgid))); 924 break; 925 default: 926 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); 927 break; 928 } 929 } 930 return real_size; 931} 932 933int 934set_posix_acl(struct mnt_idmap *idmap, struct dentry *dentry, 935 int type, struct posix_acl *acl) 936{ 937 struct inode *inode = d_inode(dentry); 938 939 if (!IS_POSIXACL(inode)) 940 return -EOPNOTSUPP; 941 if (!inode->i_op->set_acl) 942 return -EOPNOTSUPP; 943 944 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) 945 return acl ? -EACCES : 0; 946 if (!inode_owner_or_capable(idmap, inode)) 947 return -EPERM; 948 949 if (acl) { 950 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl); 951 if (ret) 952 return ret; 953 } 954 return inode->i_op->set_acl(idmap, dentry, acl, type); 955} 956EXPORT_SYMBOL(set_posix_acl); 957 958int posix_acl_listxattr(struct inode *inode, char **buffer, 959 ssize_t *remaining_size) 960{ 961 int err; 962 963 if (!IS_POSIXACL(inode)) 964 return 0; 965 966 if (inode->i_acl) { 967 err = xattr_list_one(buffer, remaining_size, 968 XATTR_NAME_POSIX_ACL_ACCESS); 969 if (err) 970 return err; 971 } 972 973 if (inode->i_default_acl) { 974 err = xattr_list_one(buffer, remaining_size, 975 XATTR_NAME_POSIX_ACL_DEFAULT); 976 if (err) 977 return err; 978 } 979 980 return 0; 981} 982 983static bool 984posix_acl_xattr_list(struct dentry *dentry) 985{ 986 return IS_POSIXACL(d_backing_inode(dentry)); 987} 988 989/* 990 * nop_posix_acl_access - legacy xattr handler for access POSIX ACLs 991 * 992 * This is the legacy POSIX ACL access xattr handler. It is used by some 993 * filesystems to implement their ->listxattr() inode operation. New code 994 * should never use them. 995 */ 996const struct xattr_handler nop_posix_acl_access = { 997 .name = XATTR_NAME_POSIX_ACL_ACCESS, 998 .list = posix_acl_xattr_list, 999}; 1000EXPORT_SYMBOL_GPL(nop_posix_acl_access); 1001 1002/* 1003 * nop_posix_acl_default - legacy xattr handler for default POSIX ACLs 1004 * 1005 * This is the legacy POSIX ACL default xattr handler. It is used by some 1006 * filesystems to implement their ->listxattr() inode operation. New code 1007 * should never use them. 1008 */ 1009const struct xattr_handler nop_posix_acl_default = { 1010 .name = XATTR_NAME_POSIX_ACL_DEFAULT, 1011 .list = posix_acl_xattr_list, 1012}; 1013EXPORT_SYMBOL_GPL(nop_posix_acl_default); 1014 1015int simple_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, 1016 struct posix_acl *acl, int type) 1017{ 1018 int error; 1019 struct inode *inode = d_inode(dentry); 1020 1021 if (type == ACL_TYPE_ACCESS) { 1022 error = posix_acl_update_mode(idmap, inode, 1023 &inode->i_mode, &acl); 1024 if (error) 1025 return error; 1026 } 1027 1028 inode_set_ctime_current(inode); 1029 if (IS_I_VERSION(inode)) 1030 inode_inc_iversion(inode); 1031 set_cached_acl(inode, type, acl); 1032 return 0; 1033} 1034 1035int simple_acl_create(struct inode *dir, struct inode *inode) 1036{ 1037 struct posix_acl *default_acl, *acl; 1038 int error; 1039 1040 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); 1041 if (error) 1042 return error; 1043 1044 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl); 1045 set_cached_acl(inode, ACL_TYPE_ACCESS, acl); 1046 1047 if (default_acl) 1048 posix_acl_release(default_acl); 1049 if (acl) 1050 posix_acl_release(acl); 1051 return 0; 1052} 1053 1054static int vfs_set_acl_idmapped_mnt(struct mnt_idmap *idmap, 1055 struct user_namespace *fs_userns, 1056 struct posix_acl *acl) 1057{ 1058 for (int n = 0; n < acl->a_count; n++) { 1059 struct posix_acl_entry *acl_e = &acl->a_entries[n]; 1060 1061 switch (acl_e->e_tag) { 1062 case ACL_USER: 1063 acl_e->e_uid = from_vfsuid(idmap, fs_userns, 1064 VFSUIDT_INIT(acl_e->e_uid)); 1065 break; 1066 case ACL_GROUP: 1067 acl_e->e_gid = from_vfsgid(idmap, fs_userns, 1068 VFSGIDT_INIT(acl_e->e_gid)); 1069 break; 1070 } 1071 } 1072 1073 return 0; 1074} 1075 1076/** 1077 * vfs_set_acl - set posix acls 1078 * @idmap: idmap of the mount 1079 * @dentry: the dentry based on which to set the posix acls 1080 * @acl_name: the name of the posix acl 1081 * @kacl: the posix acls in the appropriate VFS format 1082 * 1083 * This function sets @kacl. The caller must all posix_acl_release() on @kacl 1084 * afterwards. 1085 * 1086 * Return: On success 0, on error negative errno. 1087 */ 1088int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, 1089 const char *acl_name, struct posix_acl *kacl) 1090{ 1091 int acl_type; 1092 int error; 1093 struct inode *inode = d_inode(dentry); 1094 struct delegated_inode delegated_inode = { }; 1095 1096 acl_type = posix_acl_type(acl_name); 1097 if (acl_type < 0) 1098 return -EINVAL; 1099 1100 if (kacl) { 1101 /* 1102 * If we're on an idmapped mount translate from mount specific 1103 * vfs{g,u}id_t into global filesystem k{g,u}id_t. 1104 * Afterwards we can cache the POSIX ACLs filesystem wide and - 1105 * if this is a filesystem with a backing store - ultimately 1106 * translate them to backing store values. 1107 */ 1108 error = vfs_set_acl_idmapped_mnt(idmap, i_user_ns(inode), kacl); 1109 if (error) 1110 return error; 1111 } 1112 1113retry_deleg: 1114 inode_lock(inode); 1115 1116 /* 1117 * We only care about restrictions the inode struct itself places upon 1118 * us otherwise POSIX ACLs aren't subject to any VFS restrictions. 1119 */ 1120 error = may_write_xattr(idmap, inode); 1121 if (error) 1122 goto out_inode_unlock; 1123 1124 error = security_inode_set_acl(idmap, dentry, acl_name, kacl); 1125 if (error) 1126 goto out_inode_unlock; 1127 1128 error = try_break_deleg(inode, &delegated_inode); 1129 if (error) 1130 goto out_inode_unlock; 1131 1132 if (likely(!is_bad_inode(inode))) 1133 error = set_posix_acl(idmap, dentry, acl_type, kacl); 1134 else 1135 error = -EIO; 1136 if (!error) { 1137 fsnotify_xattr(dentry); 1138 security_inode_post_set_acl(dentry, acl_name, kacl); 1139 } 1140 1141out_inode_unlock: 1142 inode_unlock(inode); 1143 1144 if (is_delegated(&delegated_inode)) { 1145 error = break_deleg_wait(&delegated_inode); 1146 if (!error) 1147 goto retry_deleg; 1148 } 1149 1150 return error; 1151} 1152EXPORT_SYMBOL_GPL(vfs_set_acl); 1153 1154/** 1155 * vfs_get_acl - get posix acls 1156 * @idmap: idmap of the mount 1157 * @dentry: the dentry based on which to retrieve the posix acls 1158 * @acl_name: the name of the posix acl 1159 * 1160 * This function retrieves @kacl from the filesystem. The caller must all 1161 * posix_acl_release() on @kacl. 1162 * 1163 * Return: On success POSIX ACLs in VFS format, on error negative errno. 1164 */ 1165struct posix_acl *vfs_get_acl(struct mnt_idmap *idmap, 1166 struct dentry *dentry, const char *acl_name) 1167{ 1168 struct inode *inode = d_inode(dentry); 1169 struct posix_acl *acl; 1170 int acl_type, error; 1171 1172 acl_type = posix_acl_type(acl_name); 1173 if (acl_type < 0) 1174 return ERR_PTR(-EINVAL); 1175 1176 /* 1177 * The VFS has no restrictions on reading POSIX ACLs so calling 1178 * something like xattr_permission() isn't needed. Only LSMs get a say. 1179 */ 1180 error = security_inode_get_acl(idmap, dentry, acl_name); 1181 if (error) 1182 return ERR_PTR(error); 1183 1184 if (!IS_POSIXACL(inode)) 1185 return ERR_PTR(-EOPNOTSUPP); 1186 if (S_ISLNK(inode->i_mode)) 1187 return ERR_PTR(-EOPNOTSUPP); 1188 1189 acl = __get_acl(idmap, dentry, inode, acl_type); 1190 if (IS_ERR(acl)) 1191 return acl; 1192 if (!acl) 1193 return ERR_PTR(-ENODATA); 1194 1195 return acl; 1196} 1197EXPORT_SYMBOL_GPL(vfs_get_acl); 1198 1199/** 1200 * vfs_remove_acl - remove posix acls 1201 * @idmap: idmap of the mount 1202 * @dentry: the dentry based on which to retrieve the posix acls 1203 * @acl_name: the name of the posix acl 1204 * 1205 * This function removes posix acls. 1206 * 1207 * Return: On success 0, on error negative errno. 1208 */ 1209int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry, 1210 const char *acl_name) 1211{ 1212 int acl_type; 1213 int error; 1214 struct inode *inode = d_inode(dentry); 1215 struct delegated_inode delegated_inode = { }; 1216 1217 acl_type = posix_acl_type(acl_name); 1218 if (acl_type < 0) 1219 return -EINVAL; 1220 1221retry_deleg: 1222 inode_lock(inode); 1223 1224 /* 1225 * We only care about restrictions the inode struct itself places upon 1226 * us otherwise POSIX ACLs aren't subject to any VFS restrictions. 1227 */ 1228 error = may_write_xattr(idmap, inode); 1229 if (error) 1230 goto out_inode_unlock; 1231 1232 error = security_inode_remove_acl(idmap, dentry, acl_name); 1233 if (error) 1234 goto out_inode_unlock; 1235 1236 error = try_break_deleg(inode, &delegated_inode); 1237 if (error) 1238 goto out_inode_unlock; 1239 1240 if (likely(!is_bad_inode(inode))) 1241 error = set_posix_acl(idmap, dentry, acl_type, NULL); 1242 else 1243 error = -EIO; 1244 if (!error) { 1245 fsnotify_xattr(dentry); 1246 security_inode_post_remove_acl(idmap, dentry, acl_name); 1247 } 1248 1249out_inode_unlock: 1250 inode_unlock(inode); 1251 1252 if (is_delegated(&delegated_inode)) { 1253 error = break_deleg_wait(&delegated_inode); 1254 if (!error) 1255 goto retry_deleg; 1256 } 1257 1258 return error; 1259} 1260EXPORT_SYMBOL_GPL(vfs_remove_acl); 1261 1262int do_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, 1263 const char *acl_name, const void *kvalue, size_t size) 1264{ 1265 int error; 1266 struct posix_acl *acl = NULL; 1267 1268 if (size) { 1269 /* 1270 * Note that posix_acl_from_xattr() uses GFP_NOFS when it 1271 * probably doesn't need to here. 1272 */ 1273 acl = posix_acl_from_xattr(current_user_ns(), kvalue, size); 1274 if (IS_ERR(acl)) 1275 return PTR_ERR(acl); 1276 } 1277 1278 error = vfs_set_acl(idmap, dentry, acl_name, acl); 1279 posix_acl_release(acl); 1280 return error; 1281} 1282 1283ssize_t do_get_acl(struct mnt_idmap *idmap, struct dentry *dentry, 1284 const char *acl_name, void *kvalue, size_t size) 1285{ 1286 ssize_t error; 1287 struct posix_acl *acl; 1288 1289 acl = vfs_get_acl(idmap, dentry, acl_name); 1290 if (IS_ERR(acl)) 1291 return PTR_ERR(acl); 1292 1293 error = vfs_posix_acl_to_xattr(idmap, d_inode(dentry), 1294 acl, kvalue, size); 1295 posix_acl_release(acl); 1296 return error; 1297}
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