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/evm.h> 30 #include <linux/fsnotify.h> 31 32 #include "internal.h" 33 34 static 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 46 struct 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 } 63 EXPORT_SYMBOL(get_cached_acl); 64 65 struct 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 } 79 EXPORT_SYMBOL(get_cached_acl_rcu); 80 81 void 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 } 90 EXPORT_SYMBOL(set_cached_acl); 91 92 static 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 } 100 101 void forget_cached_acl(struct inode *inode, int type) 102 { 103 __forget_cached_acl(acl_by_type(inode, type)); 104 } 105 EXPORT_SYMBOL(forget_cached_acl); 106 107 void forget_all_cached_acls(struct inode *inode) 108 { 109 __forget_cached_acl(&inode->i_acl); 110 __forget_cached_acl(&inode->i_default_acl); 111 } 112 EXPORT_SYMBOL(forget_all_cached_acls); 113 114 static struct posix_acl *__get_acl(struct user_namespace *mnt_userns, 115 struct dentry *dentry, struct inode *inode, 116 int type) 117 { 118 void *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(mnt_userns, 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(cmpxchg(p, sentinel, acl) != sentinel)) 178 posix_acl_release(acl); 179 return acl; 180 } 181 182 struct posix_acl *get_inode_acl(struct inode *inode, int type) 183 { 184 return __get_acl(&init_user_ns, NULL, inode, type); 185 } 186 EXPORT_SYMBOL(get_inode_acl); 187 188 /* 189 * Init a fresh posix_acl 190 */ 191 void 192 posix_acl_init(struct posix_acl *acl, int count) 193 { 194 refcount_set(&acl->a_refcount, 1); 195 acl->a_count = count; 196 } 197 EXPORT_SYMBOL(posix_acl_init); 198 199 /* 200 * Allocate a new ACL with the specified number of entries. 201 */ 202 struct posix_acl * 203 posix_acl_alloc(int count, gfp_t flags) 204 { 205 const size_t size = sizeof(struct posix_acl) + 206 count * sizeof(struct posix_acl_entry); 207 struct posix_acl *acl = kmalloc(size, flags); 208 if (acl) 209 posix_acl_init(acl, count); 210 return acl; 211 } 212 EXPORT_SYMBOL(posix_acl_alloc); 213 214 /* 215 * Clone an ACL. 216 */ 217 struct posix_acl * 218 posix_acl_clone(const struct posix_acl *acl, gfp_t flags) 219 { 220 struct posix_acl *clone = NULL; 221 222 if (acl) { 223 int size = sizeof(struct posix_acl) + acl->a_count * 224 sizeof(struct posix_acl_entry); 225 clone = kmemdup(acl, size, flags); 226 if (clone) 227 refcount_set(&clone->a_refcount, 1); 228 } 229 return clone; 230 } 231 EXPORT_SYMBOL_GPL(posix_acl_clone); 232 233 /* 234 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise. 235 */ 236 int 237 posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl) 238 { 239 const struct posix_acl_entry *pa, *pe; 240 int state = ACL_USER_OBJ; 241 int needs_mask = 0; 242 243 FOREACH_ACL_ENTRY(pa, acl, pe) { 244 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE)) 245 return -EINVAL; 246 switch (pa->e_tag) { 247 case ACL_USER_OBJ: 248 if (state == ACL_USER_OBJ) { 249 state = ACL_USER; 250 break; 251 } 252 return -EINVAL; 253 254 case ACL_USER: 255 if (state != ACL_USER) 256 return -EINVAL; 257 if (!kuid_has_mapping(user_ns, pa->e_uid)) 258 return -EINVAL; 259 needs_mask = 1; 260 break; 261 262 case ACL_GROUP_OBJ: 263 if (state == ACL_USER) { 264 state = ACL_GROUP; 265 break; 266 } 267 return -EINVAL; 268 269 case ACL_GROUP: 270 if (state != ACL_GROUP) 271 return -EINVAL; 272 if (!kgid_has_mapping(user_ns, pa->e_gid)) 273 return -EINVAL; 274 needs_mask = 1; 275 break; 276 277 case ACL_MASK: 278 if (state != ACL_GROUP) 279 return -EINVAL; 280 state = ACL_OTHER; 281 break; 282 283 case ACL_OTHER: 284 if (state == ACL_OTHER || 285 (state == ACL_GROUP && !needs_mask)) { 286 state = 0; 287 break; 288 } 289 return -EINVAL; 290 291 default: 292 return -EINVAL; 293 } 294 } 295 if (state == 0) 296 return 0; 297 return -EINVAL; 298 } 299 EXPORT_SYMBOL(posix_acl_valid); 300 301 /* 302 * Returns 0 if the acl can be exactly represented in the traditional 303 * file mode permission bits, or else 1. Returns -E... on error. 304 */ 305 int 306 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p) 307 { 308 const struct posix_acl_entry *pa, *pe; 309 umode_t mode = 0; 310 int not_equiv = 0; 311 312 /* 313 * A null ACL can always be presented as mode bits. 314 */ 315 if (!acl) 316 return 0; 317 318 FOREACH_ACL_ENTRY(pa, acl, pe) { 319 switch (pa->e_tag) { 320 case ACL_USER_OBJ: 321 mode |= (pa->e_perm & S_IRWXO) << 6; 322 break; 323 case ACL_GROUP_OBJ: 324 mode |= (pa->e_perm & S_IRWXO) << 3; 325 break; 326 case ACL_OTHER: 327 mode |= pa->e_perm & S_IRWXO; 328 break; 329 case ACL_MASK: 330 mode = (mode & ~S_IRWXG) | 331 ((pa->e_perm & S_IRWXO) << 3); 332 not_equiv = 1; 333 break; 334 case ACL_USER: 335 case ACL_GROUP: 336 not_equiv = 1; 337 break; 338 default: 339 return -EINVAL; 340 } 341 } 342 if (mode_p) 343 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 344 return not_equiv; 345 } 346 EXPORT_SYMBOL(posix_acl_equiv_mode); 347 348 /* 349 * Create an ACL representing the file mode permission bits of an inode. 350 */ 351 struct posix_acl * 352 posix_acl_from_mode(umode_t mode, gfp_t flags) 353 { 354 struct posix_acl *acl = posix_acl_alloc(3, flags); 355 if (!acl) 356 return ERR_PTR(-ENOMEM); 357 358 acl->a_entries[0].e_tag = ACL_USER_OBJ; 359 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6; 360 361 acl->a_entries[1].e_tag = ACL_GROUP_OBJ; 362 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3; 363 364 acl->a_entries[2].e_tag = ACL_OTHER; 365 acl->a_entries[2].e_perm = (mode & S_IRWXO); 366 return acl; 367 } 368 EXPORT_SYMBOL(posix_acl_from_mode); 369 370 /* 371 * Return 0 if current is granted want access to the inode 372 * by the acl. Returns -E... otherwise. 373 */ 374 int 375 posix_acl_permission(struct user_namespace *mnt_userns, struct inode *inode, 376 const struct posix_acl *acl, int want) 377 { 378 const struct posix_acl_entry *pa, *pe, *mask_obj; 379 struct user_namespace *fs_userns = i_user_ns(inode); 380 int found = 0; 381 vfsuid_t vfsuid; 382 vfsgid_t vfsgid; 383 384 want &= MAY_READ | MAY_WRITE | MAY_EXEC; 385 386 FOREACH_ACL_ENTRY(pa, acl, pe) { 387 switch(pa->e_tag) { 388 case ACL_USER_OBJ: 389 /* (May have been checked already) */ 390 vfsuid = i_uid_into_vfsuid(mnt_userns, inode); 391 if (vfsuid_eq_kuid(vfsuid, current_fsuid())) 392 goto check_perm; 393 break; 394 case ACL_USER: 395 vfsuid = make_vfsuid(mnt_userns, fs_userns, 396 pa->e_uid); 397 if (vfsuid_eq_kuid(vfsuid, current_fsuid())) 398 goto mask; 399 break; 400 case ACL_GROUP_OBJ: 401 vfsgid = i_gid_into_vfsgid(mnt_userns, inode); 402 if (vfsgid_in_group_p(vfsgid)) { 403 found = 1; 404 if ((pa->e_perm & want) == want) 405 goto mask; 406 } 407 break; 408 case ACL_GROUP: 409 vfsgid = make_vfsgid(mnt_userns, fs_userns, 410 pa->e_gid); 411 if (vfsgid_in_group_p(vfsgid)) { 412 found = 1; 413 if ((pa->e_perm & want) == want) 414 goto mask; 415 } 416 break; 417 case ACL_MASK: 418 break; 419 case ACL_OTHER: 420 if (found) 421 return -EACCES; 422 else 423 goto check_perm; 424 default: 425 return -EIO; 426 } 427 } 428 return -EIO; 429 430 mask: 431 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) { 432 if (mask_obj->e_tag == ACL_MASK) { 433 if ((pa->e_perm & mask_obj->e_perm & want) == want) 434 return 0; 435 return -EACCES; 436 } 437 } 438 439 check_perm: 440 if ((pa->e_perm & want) == want) 441 return 0; 442 return -EACCES; 443 } 444 445 /* 446 * Modify acl when creating a new inode. The caller must ensure the acl is 447 * only referenced once. 448 * 449 * mode_p initially must contain the mode parameter to the open() / creat() 450 * system calls. All permissions that are not granted by the acl are removed. 451 * The permissions in the acl are changed to reflect the mode_p parameter. 452 */ 453 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p) 454 { 455 struct posix_acl_entry *pa, *pe; 456 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 457 umode_t mode = *mode_p; 458 int not_equiv = 0; 459 460 /* assert(atomic_read(acl->a_refcount) == 1); */ 461 462 FOREACH_ACL_ENTRY(pa, acl, pe) { 463 switch(pa->e_tag) { 464 case ACL_USER_OBJ: 465 pa->e_perm &= (mode >> 6) | ~S_IRWXO; 466 mode &= (pa->e_perm << 6) | ~S_IRWXU; 467 break; 468 469 case ACL_USER: 470 case ACL_GROUP: 471 not_equiv = 1; 472 break; 473 474 case ACL_GROUP_OBJ: 475 group_obj = pa; 476 break; 477 478 case ACL_OTHER: 479 pa->e_perm &= mode | ~S_IRWXO; 480 mode &= pa->e_perm | ~S_IRWXO; 481 break; 482 483 case ACL_MASK: 484 mask_obj = pa; 485 not_equiv = 1; 486 break; 487 488 default: 489 return -EIO; 490 } 491 } 492 493 if (mask_obj) { 494 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 495 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG; 496 } else { 497 if (!group_obj) 498 return -EIO; 499 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 500 mode &= (group_obj->e_perm << 3) | ~S_IRWXG; 501 } 502 503 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 504 return not_equiv; 505 } 506 507 /* 508 * Modify the ACL for the chmod syscall. 509 */ 510 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode) 511 { 512 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 513 struct posix_acl_entry *pa, *pe; 514 515 /* assert(atomic_read(acl->a_refcount) == 1); */ 516 517 FOREACH_ACL_ENTRY(pa, acl, pe) { 518 switch(pa->e_tag) { 519 case ACL_USER_OBJ: 520 pa->e_perm = (mode & S_IRWXU) >> 6; 521 break; 522 523 case ACL_USER: 524 case ACL_GROUP: 525 break; 526 527 case ACL_GROUP_OBJ: 528 group_obj = pa; 529 break; 530 531 case ACL_MASK: 532 mask_obj = pa; 533 break; 534 535 case ACL_OTHER: 536 pa->e_perm = (mode & S_IRWXO); 537 break; 538 539 default: 540 return -EIO; 541 } 542 } 543 544 if (mask_obj) { 545 mask_obj->e_perm = (mode & S_IRWXG) >> 3; 546 } else { 547 if (!group_obj) 548 return -EIO; 549 group_obj->e_perm = (mode & S_IRWXG) >> 3; 550 } 551 552 return 0; 553 } 554 555 int 556 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p) 557 { 558 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 559 int err = -ENOMEM; 560 if (clone) { 561 err = posix_acl_create_masq(clone, mode_p); 562 if (err < 0) { 563 posix_acl_release(clone); 564 clone = NULL; 565 } 566 } 567 posix_acl_release(*acl); 568 *acl = clone; 569 return err; 570 } 571 EXPORT_SYMBOL(__posix_acl_create); 572 573 int 574 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode) 575 { 576 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 577 int err = -ENOMEM; 578 if (clone) { 579 err = __posix_acl_chmod_masq(clone, mode); 580 if (err) { 581 posix_acl_release(clone); 582 clone = NULL; 583 } 584 } 585 posix_acl_release(*acl); 586 *acl = clone; 587 return err; 588 } 589 EXPORT_SYMBOL(__posix_acl_chmod); 590 591 /** 592 * posix_acl_chmod - chmod a posix acl 593 * 594 * @mnt_userns: user namespace of the mount @inode was found from 595 * @dentry: dentry to check permissions on 596 * @mode: the new mode of @inode 597 * 598 * If the dentry has been found through an idmapped mount the user namespace of 599 * the vfsmount must be passed through @mnt_userns. This function will then 600 * take care to map the inode according to @mnt_userns before checking 601 * permissions. On non-idmapped mounts or if permission checking is to be 602 * performed on the raw inode simply passs init_user_ns. 603 */ 604 int 605 posix_acl_chmod(struct user_namespace *mnt_userns, struct dentry *dentry, 606 umode_t mode) 607 { 608 struct inode *inode = d_inode(dentry); 609 struct posix_acl *acl; 610 int ret = 0; 611 612 if (!IS_POSIXACL(inode)) 613 return 0; 614 if (!inode->i_op->set_acl) 615 return -EOPNOTSUPP; 616 617 acl = get_inode_acl(inode, ACL_TYPE_ACCESS); 618 if (IS_ERR_OR_NULL(acl)) { 619 if (acl == ERR_PTR(-EOPNOTSUPP)) 620 return 0; 621 return PTR_ERR(acl); 622 } 623 624 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode); 625 if (ret) 626 return ret; 627 ret = inode->i_op->set_acl(mnt_userns, dentry, acl, ACL_TYPE_ACCESS); 628 posix_acl_release(acl); 629 return ret; 630 } 631 EXPORT_SYMBOL(posix_acl_chmod); 632 633 int 634 posix_acl_create(struct inode *dir, umode_t *mode, 635 struct posix_acl **default_acl, struct posix_acl **acl) 636 { 637 struct posix_acl *p; 638 struct posix_acl *clone; 639 int ret; 640 641 *acl = NULL; 642 *default_acl = NULL; 643 644 if (S_ISLNK(*mode) || !IS_POSIXACL(dir)) 645 return 0; 646 647 p = get_inode_acl(dir, ACL_TYPE_DEFAULT); 648 if (!p || p == ERR_PTR(-EOPNOTSUPP)) { 649 *mode &= ~current_umask(); 650 return 0; 651 } 652 if (IS_ERR(p)) 653 return PTR_ERR(p); 654 655 ret = -ENOMEM; 656 clone = posix_acl_clone(p, GFP_NOFS); 657 if (!clone) 658 goto err_release; 659 660 ret = posix_acl_create_masq(clone, mode); 661 if (ret < 0) 662 goto err_release_clone; 663 664 if (ret == 0) 665 posix_acl_release(clone); 666 else 667 *acl = clone; 668 669 if (!S_ISDIR(*mode)) 670 posix_acl_release(p); 671 else 672 *default_acl = p; 673 674 return 0; 675 676 err_release_clone: 677 posix_acl_release(clone); 678 err_release: 679 posix_acl_release(p); 680 return ret; 681 } 682 EXPORT_SYMBOL_GPL(posix_acl_create); 683 684 /** 685 * posix_acl_update_mode - update mode in set_acl 686 * @mnt_userns: user namespace of the mount @inode was found from 687 * @inode: target inode 688 * @mode_p: mode (pointer) for update 689 * @acl: acl pointer 690 * 691 * Update the file mode when setting an ACL: compute the new file permission 692 * bits based on the ACL. In addition, if the ACL is equivalent to the new 693 * file mode, set *@acl to NULL to indicate that no ACL should be set. 694 * 695 * As with chmod, clear the setgid bit if the caller is not in the owning group 696 * or capable of CAP_FSETID (see inode_change_ok). 697 * 698 * If the inode has been found through an idmapped mount the user namespace of 699 * the vfsmount must be passed through @mnt_userns. This function will then 700 * take care to map the inode according to @mnt_userns before checking 701 * permissions. On non-idmapped mounts or if permission checking is to be 702 * performed on the raw inode simply passs init_user_ns. 703 * 704 * Called from set_acl inode operations. 705 */ 706 int posix_acl_update_mode(struct user_namespace *mnt_userns, 707 struct inode *inode, umode_t *mode_p, 708 struct posix_acl **acl) 709 { 710 umode_t mode = inode->i_mode; 711 int error; 712 713 error = posix_acl_equiv_mode(*acl, &mode); 714 if (error < 0) 715 return error; 716 if (error == 0) 717 *acl = NULL; 718 if (!vfsgid_in_group_p(i_gid_into_vfsgid(mnt_userns, inode)) && 719 !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID)) 720 mode &= ~S_ISGID; 721 *mode_p = mode; 722 return 0; 723 } 724 EXPORT_SYMBOL(posix_acl_update_mode); 725 726 /* 727 * Fix up the uids and gids in posix acl extended attributes in place. 728 */ 729 static int posix_acl_fix_xattr_common(const void *value, size_t size) 730 { 731 const struct posix_acl_xattr_header *header = value; 732 int count; 733 734 if (!header) 735 return -EINVAL; 736 if (size < sizeof(struct posix_acl_xattr_header)) 737 return -EINVAL; 738 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 739 return -EOPNOTSUPP; 740 741 count = posix_acl_xattr_count(size); 742 if (count < 0) 743 return -EINVAL; 744 if (count == 0) 745 return 0; 746 747 return count; 748 } 749 750 void posix_acl_getxattr_idmapped_mnt(struct user_namespace *mnt_userns, 751 const struct inode *inode, 752 void *value, size_t size) 753 { 754 struct posix_acl_xattr_header *header = value; 755 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; 756 struct user_namespace *fs_userns = i_user_ns(inode); 757 int count; 758 vfsuid_t vfsuid; 759 vfsgid_t vfsgid; 760 kuid_t uid; 761 kgid_t gid; 762 763 if (no_idmapping(mnt_userns, i_user_ns(inode))) 764 return; 765 766 count = posix_acl_fix_xattr_common(value, size); 767 if (count <= 0) 768 return; 769 770 for (end = entry + count; entry != end; entry++) { 771 switch (le16_to_cpu(entry->e_tag)) { 772 case ACL_USER: 773 uid = make_kuid(&init_user_ns, le32_to_cpu(entry->e_id)); 774 vfsuid = make_vfsuid(mnt_userns, fs_userns, uid); 775 entry->e_id = cpu_to_le32(from_kuid(&init_user_ns, 776 vfsuid_into_kuid(vfsuid))); 777 break; 778 case ACL_GROUP: 779 gid = make_kgid(&init_user_ns, le32_to_cpu(entry->e_id)); 780 vfsgid = make_vfsgid(mnt_userns, fs_userns, gid); 781 entry->e_id = cpu_to_le32(from_kgid(&init_user_ns, 782 vfsgid_into_kgid(vfsgid))); 783 break; 784 default: 785 break; 786 } 787 } 788 } 789 790 static void posix_acl_fix_xattr_userns( 791 struct user_namespace *to, struct user_namespace *from, 792 void *value, size_t size) 793 { 794 struct posix_acl_xattr_header *header = value; 795 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; 796 int count; 797 kuid_t uid; 798 kgid_t gid; 799 800 count = posix_acl_fix_xattr_common(value, size); 801 if (count <= 0) 802 return; 803 804 for (end = entry + count; entry != end; entry++) { 805 switch(le16_to_cpu(entry->e_tag)) { 806 case ACL_USER: 807 uid = make_kuid(from, le32_to_cpu(entry->e_id)); 808 entry->e_id = cpu_to_le32(from_kuid(to, uid)); 809 break; 810 case ACL_GROUP: 811 gid = make_kgid(from, le32_to_cpu(entry->e_id)); 812 entry->e_id = cpu_to_le32(from_kgid(to, gid)); 813 break; 814 default: 815 break; 816 } 817 } 818 } 819 820 void posix_acl_fix_xattr_from_user(void *value, size_t size) 821 { 822 struct user_namespace *user_ns = current_user_ns(); 823 if (user_ns == &init_user_ns) 824 return; 825 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size); 826 } 827 828 void posix_acl_fix_xattr_to_user(void *value, size_t size) 829 { 830 struct user_namespace *user_ns = current_user_ns(); 831 if (user_ns == &init_user_ns) 832 return; 833 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size); 834 } 835 836 /** 837 * make_posix_acl - convert POSIX ACLs from uapi to VFS format using the 838 * provided callbacks to map ACL_{GROUP,USER} entries into the 839 * appropriate format 840 * @mnt_userns: the mount's idmapping 841 * @fs_userns: the filesystem's idmapping 842 * @value: the uapi representation of POSIX ACLs 843 * @size: the size of @void 844 * @uid_cb: callback to use for mapping the uid stored in ACL_USER entries 845 * @gid_cb: callback to use for mapping the gid stored in ACL_GROUP entries 846 * 847 * The make_posix_acl() helper is an abstraction to translate from uapi format 848 * into the VFS format allowing the caller to specific callbacks to map 849 * ACL_{GROUP,USER} entries into the expected format. This is used in 850 * posix_acl_from_xattr() and vfs_set_acl_prepare() and avoids pointless code 851 * duplication. 852 * 853 * Return: Allocated struct posix_acl on success, NULL for a valid header but 854 * without actual POSIX ACL entries, or ERR_PTR() encoded error code. 855 */ 856 static struct posix_acl *make_posix_acl(struct user_namespace *mnt_userns, 857 struct user_namespace *fs_userns, const void *value, size_t size, 858 kuid_t (*uid_cb)(struct user_namespace *, struct user_namespace *, 859 const struct posix_acl_xattr_entry *), 860 kgid_t (*gid_cb)(struct user_namespace *, struct user_namespace *, 861 const struct posix_acl_xattr_entry *)) 862 { 863 const struct posix_acl_xattr_header *header = value; 864 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end; 865 int count; 866 struct posix_acl *acl; 867 struct posix_acl_entry *acl_e; 868 869 count = posix_acl_fix_xattr_common(value, size); 870 if (count < 0) 871 return ERR_PTR(count); 872 if (count == 0) 873 return NULL; 874 875 acl = posix_acl_alloc(count, GFP_NOFS); 876 if (!acl) 877 return ERR_PTR(-ENOMEM); 878 acl_e = acl->a_entries; 879 880 for (end = entry + count; entry != end; acl_e++, entry++) { 881 acl_e->e_tag = le16_to_cpu(entry->e_tag); 882 acl_e->e_perm = le16_to_cpu(entry->e_perm); 883 884 switch(acl_e->e_tag) { 885 case ACL_USER_OBJ: 886 case ACL_GROUP_OBJ: 887 case ACL_MASK: 888 case ACL_OTHER: 889 break; 890 891 case ACL_USER: 892 acl_e->e_uid = uid_cb(mnt_userns, fs_userns, entry); 893 if (!uid_valid(acl_e->e_uid)) 894 goto fail; 895 break; 896 case ACL_GROUP: 897 acl_e->e_gid = gid_cb(mnt_userns, fs_userns, entry); 898 if (!gid_valid(acl_e->e_gid)) 899 goto fail; 900 break; 901 902 default: 903 goto fail; 904 } 905 } 906 return acl; 907 908 fail: 909 posix_acl_release(acl); 910 return ERR_PTR(-EINVAL); 911 } 912 913 /** 914 * vfs_set_acl_prepare_kuid - map ACL_USER uid according to mount- and 915 * filesystem idmapping 916 * @mnt_userns: the mount's idmapping 917 * @fs_userns: the filesystem's idmapping 918 * @e: a ACL_USER entry in POSIX ACL uapi format 919 * 920 * The uid stored as ACL_USER entry in @e is a kuid_t stored as a raw {g,u}id 921 * value. The vfs_set_acl_prepare_kuid() will recover the kuid_t through 922 * KUIDT_INIT() and then map it according to the idmapped mount. The resulting 923 * kuid_t is the value which the filesystem can map up into a raw backing store 924 * id in the filesystem's idmapping. 925 * 926 * This is used in vfs_set_acl_prepare() to generate the proper VFS 927 * representation of POSIX ACLs with ACL_USER entries during setxattr(). 928 * 929 * Return: A kuid in @fs_userns for the uid stored in @e. 930 */ 931 static inline kuid_t 932 vfs_set_acl_prepare_kuid(struct user_namespace *mnt_userns, 933 struct user_namespace *fs_userns, 934 const struct posix_acl_xattr_entry *e) 935 { 936 kuid_t kuid = KUIDT_INIT(le32_to_cpu(e->e_id)); 937 return from_vfsuid(mnt_userns, fs_userns, VFSUIDT_INIT(kuid)); 938 } 939 940 /** 941 * vfs_set_acl_prepare_kgid - map ACL_GROUP gid according to mount- and 942 * filesystem idmapping 943 * @mnt_userns: the mount's idmapping 944 * @fs_userns: the filesystem's idmapping 945 * @e: a ACL_GROUP entry in POSIX ACL uapi format 946 * 947 * The gid stored as ACL_GROUP entry in @e is a kgid_t stored as a raw {g,u}id 948 * value. The vfs_set_acl_prepare_kgid() will recover the kgid_t through 949 * KGIDT_INIT() and then map it according to the idmapped mount. The resulting 950 * kgid_t is the value which the filesystem can map up into a raw backing store 951 * id in the filesystem's idmapping. 952 * 953 * This is used in vfs_set_acl_prepare() to generate the proper VFS 954 * representation of POSIX ACLs with ACL_GROUP entries during setxattr(). 955 * 956 * Return: A kgid in @fs_userns for the gid stored in @e. 957 */ 958 static inline kgid_t 959 vfs_set_acl_prepare_kgid(struct user_namespace *mnt_userns, 960 struct user_namespace *fs_userns, 961 const struct posix_acl_xattr_entry *e) 962 { 963 kgid_t kgid = KGIDT_INIT(le32_to_cpu(e->e_id)); 964 return from_vfsgid(mnt_userns, fs_userns, VFSGIDT_INIT(kgid)); 965 } 966 967 /** 968 * vfs_set_acl_prepare - convert POSIX ACLs from uapi to VFS format taking 969 * mount and filesystem idmappings into account 970 * @mnt_userns: the mount's idmapping 971 * @fs_userns: the filesystem's idmapping 972 * @value: the uapi representation of POSIX ACLs 973 * @size: the size of @void 974 * 975 * When setting POSIX ACLs with ACL_{GROUP,USER} entries they need to be 976 * mapped according to the relevant mount- and filesystem idmapping. It is 977 * important that the ACL_{GROUP,USER} entries in struct posix_acl will be 978 * mapped into k{g,u}id_t that are supposed to be mapped up in the filesystem 979 * idmapping. This is crucial since the resulting struct posix_acl might be 980 * cached filesystem wide. The vfs_set_acl_prepare() function will take care to 981 * perform all necessary idmappings. 982 * 983 * Note, that since basically forever the {g,u}id values encoded as 984 * ACL_{GROUP,USER} entries in the uapi POSIX ACLs passed via @value contain 985 * values that have been mapped according to the caller's idmapping. In other 986 * words, POSIX ACLs passed in uapi format as @value during setxattr() contain 987 * {g,u}id values in their ACL_{GROUP,USER} entries that should actually have 988 * been stored as k{g,u}id_t. 989 * 990 * This means, vfs_set_acl_prepare() needs to first recover the k{g,u}id_t by 991 * calling K{G,U}IDT_INIT(). Afterwards they can be interpreted as vfs{g,u}id_t 992 * through from_vfs{g,u}id() to account for any idmapped mounts. The 993 * vfs_set_acl_prepare_k{g,u}id() helpers will take care to generate the 994 * correct k{g,u}id_t. 995 * 996 * The filesystem will then receive the POSIX ACLs ready to be cached 997 * filesystem wide and ready to be written to the backing store taking the 998 * filesystem's idmapping into account. 999 * 1000 * Return: Allocated struct posix_acl on success, NULL for a valid header but 1001 * without actual POSIX ACL entries, or ERR_PTR() encoded error code. 1002 */ 1003 struct posix_acl *vfs_set_acl_prepare(struct user_namespace *mnt_userns, 1004 struct user_namespace *fs_userns, 1005 const void *value, size_t size) 1006 { 1007 return make_posix_acl(mnt_userns, fs_userns, value, size, 1008 vfs_set_acl_prepare_kuid, 1009 vfs_set_acl_prepare_kgid); 1010 } 1011 EXPORT_SYMBOL(vfs_set_acl_prepare); 1012 1013 /** 1014 * posix_acl_from_xattr_kuid - map ACL_USER uid into filesystem idmapping 1015 * @mnt_userns: unused 1016 * @fs_userns: the filesystem's idmapping 1017 * @e: a ACL_USER entry in POSIX ACL uapi format 1018 * 1019 * Map the uid stored as ACL_USER entry in @e into the filesystem's idmapping. 1020 * This is used in posix_acl_from_xattr() to generate the proper VFS 1021 * representation of POSIX ACLs with ACL_USER entries. 1022 * 1023 * Return: A kuid in @fs_userns for the uid stored in @e. 1024 */ 1025 static inline kuid_t 1026 posix_acl_from_xattr_kuid(struct user_namespace *mnt_userns, 1027 struct user_namespace *fs_userns, 1028 const struct posix_acl_xattr_entry *e) 1029 { 1030 return make_kuid(fs_userns, le32_to_cpu(e->e_id)); 1031 } 1032 1033 /** 1034 * posix_acl_from_xattr_kgid - map ACL_GROUP gid into filesystem idmapping 1035 * @mnt_userns: unused 1036 * @fs_userns: the filesystem's idmapping 1037 * @e: a ACL_GROUP entry in POSIX ACL uapi format 1038 * 1039 * Map the gid stored as ACL_GROUP entry in @e into the filesystem's idmapping. 1040 * This is used in posix_acl_from_xattr() to generate the proper VFS 1041 * representation of POSIX ACLs with ACL_GROUP entries. 1042 * 1043 * Return: A kgid in @fs_userns for the gid stored in @e. 1044 */ 1045 static inline kgid_t 1046 posix_acl_from_xattr_kgid(struct user_namespace *mnt_userns, 1047 struct user_namespace *fs_userns, 1048 const struct posix_acl_xattr_entry *e) 1049 { 1050 return make_kgid(fs_userns, le32_to_cpu(e->e_id)); 1051 } 1052 1053 /** 1054 * posix_acl_from_xattr - convert POSIX ACLs from backing store to VFS format 1055 * @fs_userns: the filesystem's idmapping 1056 * @value: the uapi representation of POSIX ACLs 1057 * @size: the size of @void 1058 * 1059 * Filesystems that store POSIX ACLs in the unaltered uapi format should use 1060 * posix_acl_from_xattr() when reading them from the backing store and 1061 * converting them into the struct posix_acl VFS format. The helper is 1062 * specifically intended to be called from the ->get_inode_acl() inode 1063 * operation. 1064 * 1065 * The posix_acl_from_xattr() function will map the raw {g,u}id values stored 1066 * in ACL_{GROUP,USER} entries into the filesystem idmapping in @fs_userns. The 1067 * posix_acl_from_xattr_k{g,u}id() helpers will take care to generate the 1068 * correct k{g,u}id_t. The returned struct posix_acl can be cached. 1069 * 1070 * Note that posix_acl_from_xattr() does not take idmapped mounts into account. 1071 * If it did it calling is from the ->get_inode_acl() inode operation would 1072 * return POSIX ACLs mapped according to an idmapped mount which would mean 1073 * that the value couldn't be cached for the filesystem. Idmapped mounts are 1074 * taken into account on the fly during permission checking or right at the VFS 1075 * - userspace boundary before reporting them to the user. 1076 * 1077 * Return: Allocated struct posix_acl on success, NULL for a valid header but 1078 * without actual POSIX ACL entries, or ERR_PTR() encoded error code. 1079 */ 1080 struct posix_acl * 1081 posix_acl_from_xattr(struct user_namespace *fs_userns, 1082 const void *value, size_t size) 1083 { 1084 return make_posix_acl(&init_user_ns, fs_userns, value, size, 1085 posix_acl_from_xattr_kuid, 1086 posix_acl_from_xattr_kgid); 1087 } 1088 EXPORT_SYMBOL (posix_acl_from_xattr); 1089 1090 /* 1091 * Convert from in-memory to extended attribute representation. 1092 */ 1093 int 1094 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl, 1095 void *buffer, size_t size) 1096 { 1097 struct posix_acl_xattr_header *ext_acl = buffer; 1098 struct posix_acl_xattr_entry *ext_entry; 1099 int real_size, n; 1100 1101 real_size = posix_acl_xattr_size(acl->a_count); 1102 if (!buffer) 1103 return real_size; 1104 if (real_size > size) 1105 return -ERANGE; 1106 1107 ext_entry = (void *)(ext_acl + 1); 1108 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); 1109 1110 for (n=0; n < acl->a_count; n++, ext_entry++) { 1111 const struct posix_acl_entry *acl_e = &acl->a_entries[n]; 1112 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); 1113 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); 1114 switch(acl_e->e_tag) { 1115 case ACL_USER: 1116 ext_entry->e_id = 1117 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid)); 1118 break; 1119 case ACL_GROUP: 1120 ext_entry->e_id = 1121 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid)); 1122 break; 1123 default: 1124 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); 1125 break; 1126 } 1127 } 1128 return real_size; 1129 } 1130 EXPORT_SYMBOL (posix_acl_to_xattr); 1131 1132 /** 1133 * vfs_posix_acl_to_xattr - convert from kernel to userspace representation 1134 * @mnt_userns: user namespace of the mount 1135 * @inode: inode the posix acls are set on 1136 * @acl: the posix acls as represented by the vfs 1137 * @buffer: the buffer into which to convert @acl 1138 * @size: size of @buffer 1139 * 1140 * This converts @acl from the VFS representation in the filesystem idmapping 1141 * to the uapi form reportable to userspace. And mount and caller idmappings 1142 * are handled appropriately. 1143 * 1144 * Return: On success, the size of the stored uapi posix acls, on error a 1145 * negative errno. 1146 */ 1147 ssize_t vfs_posix_acl_to_xattr(struct user_namespace *mnt_userns, 1148 struct inode *inode, const struct posix_acl *acl, 1149 void *buffer, size_t size) 1150 1151 { 1152 struct posix_acl_xattr_header *ext_acl = buffer; 1153 struct posix_acl_xattr_entry *ext_entry; 1154 struct user_namespace *fs_userns, *caller_userns; 1155 ssize_t real_size, n; 1156 vfsuid_t vfsuid; 1157 vfsgid_t vfsgid; 1158 1159 real_size = posix_acl_xattr_size(acl->a_count); 1160 if (!buffer) 1161 return real_size; 1162 if (real_size > size) 1163 return -ERANGE; 1164 1165 ext_entry = (void *)(ext_acl + 1); 1166 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); 1167 1168 fs_userns = i_user_ns(inode); 1169 caller_userns = current_user_ns(); 1170 for (n=0; n < acl->a_count; n++, ext_entry++) { 1171 const struct posix_acl_entry *acl_e = &acl->a_entries[n]; 1172 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); 1173 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); 1174 switch(acl_e->e_tag) { 1175 case ACL_USER: 1176 vfsuid = make_vfsuid(mnt_userns, fs_userns, acl_e->e_uid); 1177 ext_entry->e_id = cpu_to_le32(from_kuid( 1178 caller_userns, vfsuid_into_kuid(vfsuid))); 1179 break; 1180 case ACL_GROUP: 1181 vfsgid = make_vfsgid(mnt_userns, fs_userns, acl_e->e_gid); 1182 ext_entry->e_id = cpu_to_le32(from_kgid( 1183 caller_userns, vfsgid_into_kgid(vfsgid))); 1184 break; 1185 default: 1186 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); 1187 break; 1188 } 1189 } 1190 return real_size; 1191 } 1192 1193 static int 1194 posix_acl_xattr_get(const struct xattr_handler *handler, 1195 struct dentry *unused, struct inode *inode, 1196 const char *name, void *value, size_t size) 1197 { 1198 struct posix_acl *acl; 1199 int error; 1200 1201 if (!IS_POSIXACL(inode)) 1202 return -EOPNOTSUPP; 1203 if (S_ISLNK(inode->i_mode)) 1204 return -EOPNOTSUPP; 1205 1206 acl = get_inode_acl(inode, handler->flags); 1207 if (IS_ERR(acl)) 1208 return PTR_ERR(acl); 1209 if (acl == NULL) 1210 return -ENODATA; 1211 1212 error = posix_acl_to_xattr(&init_user_ns, acl, value, size); 1213 posix_acl_release(acl); 1214 1215 return error; 1216 } 1217 1218 int 1219 set_posix_acl(struct user_namespace *mnt_userns, struct dentry *dentry, 1220 int type, struct posix_acl *acl) 1221 { 1222 struct inode *inode = d_inode(dentry); 1223 1224 if (!IS_POSIXACL(inode)) 1225 return -EOPNOTSUPP; 1226 if (!inode->i_op->set_acl) 1227 return -EOPNOTSUPP; 1228 1229 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) 1230 return acl ? -EACCES : 0; 1231 if (!inode_owner_or_capable(mnt_userns, inode)) 1232 return -EPERM; 1233 1234 if (acl) { 1235 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl); 1236 if (ret) 1237 return ret; 1238 } 1239 return inode->i_op->set_acl(mnt_userns, dentry, acl, type); 1240 } 1241 EXPORT_SYMBOL(set_posix_acl); 1242 1243 static int 1244 posix_acl_xattr_set(const struct xattr_handler *handler, 1245 struct user_namespace *mnt_userns, 1246 struct dentry *dentry, struct inode *inode, 1247 const char *name, const void *value, size_t size, 1248 int flags) 1249 { 1250 struct posix_acl *acl = NULL; 1251 int ret; 1252 1253 if (value) { 1254 /* 1255 * By the time we end up here the {g,u}ids stored in 1256 * ACL_{GROUP,USER} have already been mapped according to the 1257 * caller's idmapping. The vfs_set_acl_prepare() helper will 1258 * recover them and take idmapped mounts into account. The 1259 * filesystem will receive the POSIX ACLs in the correct 1260 * format ready to be cached or written to the backing store 1261 * taking the filesystem idmapping into account. 1262 */ 1263 acl = vfs_set_acl_prepare(mnt_userns, i_user_ns(inode), 1264 value, size); 1265 if (IS_ERR(acl)) 1266 return PTR_ERR(acl); 1267 } 1268 ret = set_posix_acl(mnt_userns, dentry, handler->flags, acl); 1269 posix_acl_release(acl); 1270 return ret; 1271 } 1272 1273 static bool 1274 posix_acl_xattr_list(struct dentry *dentry) 1275 { 1276 return IS_POSIXACL(d_backing_inode(dentry)); 1277 } 1278 1279 const struct xattr_handler posix_acl_access_xattr_handler = { 1280 .name = XATTR_NAME_POSIX_ACL_ACCESS, 1281 .flags = ACL_TYPE_ACCESS, 1282 .list = posix_acl_xattr_list, 1283 .get = posix_acl_xattr_get, 1284 .set = posix_acl_xattr_set, 1285 }; 1286 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler); 1287 1288 const struct xattr_handler posix_acl_default_xattr_handler = { 1289 .name = XATTR_NAME_POSIX_ACL_DEFAULT, 1290 .flags = ACL_TYPE_DEFAULT, 1291 .list = posix_acl_xattr_list, 1292 .get = posix_acl_xattr_get, 1293 .set = posix_acl_xattr_set, 1294 }; 1295 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler); 1296 1297 int simple_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry, 1298 struct posix_acl *acl, int type) 1299 { 1300 int error; 1301 struct inode *inode = d_inode(dentry); 1302 1303 if (type == ACL_TYPE_ACCESS) { 1304 error = posix_acl_update_mode(mnt_userns, inode, 1305 &inode->i_mode, &acl); 1306 if (error) 1307 return error; 1308 } 1309 1310 inode->i_ctime = current_time(inode); 1311 if (IS_I_VERSION(inode)) 1312 inode_inc_iversion(inode); 1313 set_cached_acl(inode, type, acl); 1314 return 0; 1315 } 1316 1317 int simple_acl_create(struct inode *dir, struct inode *inode) 1318 { 1319 struct posix_acl *default_acl, *acl; 1320 int error; 1321 1322 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); 1323 if (error) 1324 return error; 1325 1326 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl); 1327 set_cached_acl(inode, ACL_TYPE_ACCESS, acl); 1328 1329 if (default_acl) 1330 posix_acl_release(default_acl); 1331 if (acl) 1332 posix_acl_release(acl); 1333 return 0; 1334 } 1335 1336 static int vfs_set_acl_idmapped_mnt(struct user_namespace *mnt_userns, 1337 struct user_namespace *fs_userns, 1338 struct posix_acl *acl) 1339 { 1340 for (int n = 0; n < acl->a_count; n++) { 1341 struct posix_acl_entry *acl_e = &acl->a_entries[n]; 1342 1343 switch (acl_e->e_tag) { 1344 case ACL_USER: 1345 acl_e->e_uid = from_vfsuid(mnt_userns, fs_userns, 1346 VFSUIDT_INIT(acl_e->e_uid)); 1347 break; 1348 case ACL_GROUP: 1349 acl_e->e_gid = from_vfsgid(mnt_userns, fs_userns, 1350 VFSGIDT_INIT(acl_e->e_gid)); 1351 break; 1352 } 1353 } 1354 1355 return 0; 1356 } 1357 1358 /** 1359 * vfs_set_acl - set posix acls 1360 * @mnt_userns: user namespace of the mount 1361 * @dentry: the dentry based on which to set the posix acls 1362 * @acl_name: the name of the posix acl 1363 * @kacl: the posix acls in the appropriate VFS format 1364 * 1365 * This function sets @kacl. The caller must all posix_acl_release() on @kacl 1366 * afterwards. 1367 * 1368 * Return: On success 0, on error negative errno. 1369 */ 1370 int vfs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry, 1371 const char *acl_name, struct posix_acl *kacl) 1372 { 1373 int acl_type; 1374 int error; 1375 struct inode *inode = d_inode(dentry); 1376 struct inode *delegated_inode = NULL; 1377 1378 acl_type = posix_acl_type(acl_name); 1379 if (acl_type < 0) 1380 return -EINVAL; 1381 1382 if (kacl) { 1383 /* 1384 * If we're on an idmapped mount translate from mount specific 1385 * vfs{g,u}id_t into global filesystem k{g,u}id_t. 1386 * Afterwards we can cache the POSIX ACLs filesystem wide and - 1387 * if this is a filesystem with a backing store - ultimately 1388 * translate them to backing store values. 1389 */ 1390 error = vfs_set_acl_idmapped_mnt(mnt_userns, i_user_ns(inode), kacl); 1391 if (error) 1392 return error; 1393 } 1394 1395 retry_deleg: 1396 inode_lock(inode); 1397 1398 /* 1399 * We only care about restrictions the inode struct itself places upon 1400 * us otherwise POSIX ACLs aren't subject to any VFS restrictions. 1401 */ 1402 error = may_write_xattr(mnt_userns, inode); 1403 if (error) 1404 goto out_inode_unlock; 1405 1406 error = security_inode_set_acl(mnt_userns, dentry, acl_name, kacl); 1407 if (error) 1408 goto out_inode_unlock; 1409 1410 error = try_break_deleg(inode, &delegated_inode); 1411 if (error) 1412 goto out_inode_unlock; 1413 1414 if (inode->i_opflags & IOP_XATTR) 1415 error = set_posix_acl(mnt_userns, dentry, acl_type, kacl); 1416 else if (unlikely(is_bad_inode(inode))) 1417 error = -EIO; 1418 else 1419 error = -EOPNOTSUPP; 1420 if (!error) { 1421 fsnotify_xattr(dentry); 1422 evm_inode_post_set_acl(dentry, acl_name, kacl); 1423 } 1424 1425 out_inode_unlock: 1426 inode_unlock(inode); 1427 1428 if (delegated_inode) { 1429 error = break_deleg_wait(&delegated_inode); 1430 if (!error) 1431 goto retry_deleg; 1432 } 1433 1434 return error; 1435 } 1436 EXPORT_SYMBOL_GPL(vfs_set_acl); 1437 1438 /** 1439 * vfs_get_acl - get posix acls 1440 * @mnt_userns: user namespace of the mount 1441 * @dentry: the dentry based on which to retrieve the posix acls 1442 * @acl_name: the name of the posix acl 1443 * 1444 * This function retrieves @kacl from the filesystem. The caller must all 1445 * posix_acl_release() on @kacl. 1446 * 1447 * Return: On success POSIX ACLs in VFS format, on error negative errno. 1448 */ 1449 struct posix_acl *vfs_get_acl(struct user_namespace *mnt_userns, 1450 struct dentry *dentry, const char *acl_name) 1451 { 1452 struct inode *inode = d_inode(dentry); 1453 struct posix_acl *acl; 1454 int acl_type, error; 1455 1456 acl_type = posix_acl_type(acl_name); 1457 if (acl_type < 0) 1458 return ERR_PTR(-EINVAL); 1459 1460 /* 1461 * The VFS has no restrictions on reading POSIX ACLs so calling 1462 * something like xattr_permission() isn't needed. Only LSMs get a say. 1463 */ 1464 error = security_inode_get_acl(mnt_userns, dentry, acl_name); 1465 if (error) 1466 return ERR_PTR(error); 1467 1468 if (!IS_POSIXACL(inode)) 1469 return ERR_PTR(-EOPNOTSUPP); 1470 if (S_ISLNK(inode->i_mode)) 1471 return ERR_PTR(-EOPNOTSUPP); 1472 1473 acl = __get_acl(mnt_userns, dentry, inode, acl_type); 1474 if (IS_ERR(acl)) 1475 return acl; 1476 if (!acl) 1477 return ERR_PTR(-ENODATA); 1478 1479 return acl; 1480 } 1481 EXPORT_SYMBOL_GPL(vfs_get_acl); 1482