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