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 27 static struct posix_acl **acl_by_type(struct inode *inode, int type) 28 { 29 switch (type) { 30 case ACL_TYPE_ACCESS: 31 return &inode->i_acl; 32 case ACL_TYPE_DEFAULT: 33 return &inode->i_default_acl; 34 default: 35 BUG(); 36 } 37 } 38 39 struct posix_acl *get_cached_acl(struct inode *inode, int type) 40 { 41 struct posix_acl **p = acl_by_type(inode, type); 42 struct posix_acl *acl; 43 44 for (;;) { 45 rcu_read_lock(); 46 acl = rcu_dereference(*p); 47 if (!acl || is_uncached_acl(acl) || 48 refcount_inc_not_zero(&acl->a_refcount)) 49 break; 50 rcu_read_unlock(); 51 cpu_relax(); 52 } 53 rcu_read_unlock(); 54 return acl; 55 } 56 EXPORT_SYMBOL(get_cached_acl); 57 58 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type) 59 { 60 struct posix_acl *acl = rcu_dereference(*acl_by_type(inode, type)); 61 62 if (acl == ACL_DONT_CACHE) { 63 struct posix_acl *ret; 64 65 ret = inode->i_op->get_acl(inode, type, LOOKUP_RCU); 66 if (!IS_ERR(ret)) 67 acl = ret; 68 } 69 70 return acl; 71 } 72 EXPORT_SYMBOL(get_cached_acl_rcu); 73 74 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl) 75 { 76 struct posix_acl **p = acl_by_type(inode, type); 77 struct posix_acl *old; 78 79 old = xchg(p, posix_acl_dup(acl)); 80 if (!is_uncached_acl(old)) 81 posix_acl_release(old); 82 } 83 EXPORT_SYMBOL(set_cached_acl); 84 85 static void __forget_cached_acl(struct posix_acl **p) 86 { 87 struct posix_acl *old; 88 89 old = xchg(p, ACL_NOT_CACHED); 90 if (!is_uncached_acl(old)) 91 posix_acl_release(old); 92 } 93 94 void forget_cached_acl(struct inode *inode, int type) 95 { 96 __forget_cached_acl(acl_by_type(inode, type)); 97 } 98 EXPORT_SYMBOL(forget_cached_acl); 99 100 void forget_all_cached_acls(struct inode *inode) 101 { 102 __forget_cached_acl(&inode->i_acl); 103 __forget_cached_acl(&inode->i_default_acl); 104 } 105 EXPORT_SYMBOL(forget_all_cached_acls); 106 107 struct posix_acl *get_acl(struct inode *inode, int type) 108 { 109 void *sentinel; 110 struct posix_acl **p; 111 struct posix_acl *acl; 112 113 /* 114 * The sentinel is used to detect when another operation like 115 * set_cached_acl() or forget_cached_acl() races with get_acl(). 116 * It is guaranteed that is_uncached_acl(sentinel) is true. 117 */ 118 119 acl = get_cached_acl(inode, type); 120 if (!is_uncached_acl(acl)) 121 return acl; 122 123 if (!IS_POSIXACL(inode)) 124 return NULL; 125 126 sentinel = uncached_acl_sentinel(current); 127 p = acl_by_type(inode, type); 128 129 /* 130 * If the ACL isn't being read yet, set our sentinel. Otherwise, the 131 * current value of the ACL will not be ACL_NOT_CACHED and so our own 132 * sentinel will not be set; another task will update the cache. We 133 * could wait for that other task to complete its job, but it's easier 134 * to just call ->get_acl to fetch the ACL ourself. (This is going to 135 * be an unlikely race.) 136 */ 137 if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED) 138 /* fall through */ ; 139 140 /* 141 * Normally, the ACL returned by ->get_acl will be cached. 142 * A filesystem can prevent that by calling 143 * forget_cached_acl(inode, type) in ->get_acl. 144 * 145 * If the filesystem doesn't have a get_acl() function at all, we'll 146 * just create the negative cache entry. 147 */ 148 if (!inode->i_op->get_acl) { 149 set_cached_acl(inode, type, NULL); 150 return NULL; 151 } 152 acl = inode->i_op->get_acl(inode, type, false); 153 154 if (IS_ERR(acl)) { 155 /* 156 * Remove our sentinel so that we don't block future attempts 157 * to cache the ACL. 158 */ 159 cmpxchg(p, sentinel, ACL_NOT_CACHED); 160 return acl; 161 } 162 163 /* 164 * Cache the result, but only if our sentinel is still in place. 165 */ 166 posix_acl_dup(acl); 167 if (unlikely(cmpxchg(p, sentinel, acl) != sentinel)) 168 posix_acl_release(acl); 169 return acl; 170 } 171 EXPORT_SYMBOL(get_acl); 172 173 /* 174 * Init a fresh posix_acl 175 */ 176 void 177 posix_acl_init(struct posix_acl *acl, int count) 178 { 179 refcount_set(&acl->a_refcount, 1); 180 acl->a_count = count; 181 } 182 EXPORT_SYMBOL(posix_acl_init); 183 184 /* 185 * Allocate a new ACL with the specified number of entries. 186 */ 187 struct posix_acl * 188 posix_acl_alloc(int count, gfp_t flags) 189 { 190 const size_t size = sizeof(struct posix_acl) + 191 count * sizeof(struct posix_acl_entry); 192 struct posix_acl *acl = kmalloc(size, flags); 193 if (acl) 194 posix_acl_init(acl, count); 195 return acl; 196 } 197 EXPORT_SYMBOL(posix_acl_alloc); 198 199 /* 200 * Clone an ACL. 201 */ 202 static struct posix_acl * 203 posix_acl_clone(const struct posix_acl *acl, gfp_t flags) 204 { 205 struct posix_acl *clone = NULL; 206 207 if (acl) { 208 int size = sizeof(struct posix_acl) + acl->a_count * 209 sizeof(struct posix_acl_entry); 210 clone = kmemdup(acl, size, flags); 211 if (clone) 212 refcount_set(&clone->a_refcount, 1); 213 } 214 return clone; 215 } 216 217 /* 218 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise. 219 */ 220 int 221 posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl) 222 { 223 const struct posix_acl_entry *pa, *pe; 224 int state = ACL_USER_OBJ; 225 int needs_mask = 0; 226 227 FOREACH_ACL_ENTRY(pa, acl, pe) { 228 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE)) 229 return -EINVAL; 230 switch (pa->e_tag) { 231 case ACL_USER_OBJ: 232 if (state == ACL_USER_OBJ) { 233 state = ACL_USER; 234 break; 235 } 236 return -EINVAL; 237 238 case ACL_USER: 239 if (state != ACL_USER) 240 return -EINVAL; 241 if (!kuid_has_mapping(user_ns, pa->e_uid)) 242 return -EINVAL; 243 needs_mask = 1; 244 break; 245 246 case ACL_GROUP_OBJ: 247 if (state == ACL_USER) { 248 state = ACL_GROUP; 249 break; 250 } 251 return -EINVAL; 252 253 case ACL_GROUP: 254 if (state != ACL_GROUP) 255 return -EINVAL; 256 if (!kgid_has_mapping(user_ns, pa->e_gid)) 257 return -EINVAL; 258 needs_mask = 1; 259 break; 260 261 case ACL_MASK: 262 if (state != ACL_GROUP) 263 return -EINVAL; 264 state = ACL_OTHER; 265 break; 266 267 case ACL_OTHER: 268 if (state == ACL_OTHER || 269 (state == ACL_GROUP && !needs_mask)) { 270 state = 0; 271 break; 272 } 273 return -EINVAL; 274 275 default: 276 return -EINVAL; 277 } 278 } 279 if (state == 0) 280 return 0; 281 return -EINVAL; 282 } 283 EXPORT_SYMBOL(posix_acl_valid); 284 285 /* 286 * Returns 0 if the acl can be exactly represented in the traditional 287 * file mode permission bits, or else 1. Returns -E... on error. 288 */ 289 int 290 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p) 291 { 292 const struct posix_acl_entry *pa, *pe; 293 umode_t mode = 0; 294 int not_equiv = 0; 295 296 /* 297 * A null ACL can always be presented as mode bits. 298 */ 299 if (!acl) 300 return 0; 301 302 FOREACH_ACL_ENTRY(pa, acl, pe) { 303 switch (pa->e_tag) { 304 case ACL_USER_OBJ: 305 mode |= (pa->e_perm & S_IRWXO) << 6; 306 break; 307 case ACL_GROUP_OBJ: 308 mode |= (pa->e_perm & S_IRWXO) << 3; 309 break; 310 case ACL_OTHER: 311 mode |= pa->e_perm & S_IRWXO; 312 break; 313 case ACL_MASK: 314 mode = (mode & ~S_IRWXG) | 315 ((pa->e_perm & S_IRWXO) << 3); 316 not_equiv = 1; 317 break; 318 case ACL_USER: 319 case ACL_GROUP: 320 not_equiv = 1; 321 break; 322 default: 323 return -EINVAL; 324 } 325 } 326 if (mode_p) 327 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 328 return not_equiv; 329 } 330 EXPORT_SYMBOL(posix_acl_equiv_mode); 331 332 /* 333 * Create an ACL representing the file mode permission bits of an inode. 334 */ 335 struct posix_acl * 336 posix_acl_from_mode(umode_t mode, gfp_t flags) 337 { 338 struct posix_acl *acl = posix_acl_alloc(3, flags); 339 if (!acl) 340 return ERR_PTR(-ENOMEM); 341 342 acl->a_entries[0].e_tag = ACL_USER_OBJ; 343 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6; 344 345 acl->a_entries[1].e_tag = ACL_GROUP_OBJ; 346 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3; 347 348 acl->a_entries[2].e_tag = ACL_OTHER; 349 acl->a_entries[2].e_perm = (mode & S_IRWXO); 350 return acl; 351 } 352 EXPORT_SYMBOL(posix_acl_from_mode); 353 354 /* 355 * Return 0 if current is granted want access to the inode 356 * by the acl. Returns -E... otherwise. 357 */ 358 int 359 posix_acl_permission(struct user_namespace *mnt_userns, struct inode *inode, 360 const struct posix_acl *acl, int want) 361 { 362 const struct posix_acl_entry *pa, *pe, *mask_obj; 363 int found = 0; 364 kuid_t uid; 365 kgid_t gid; 366 367 want &= MAY_READ | MAY_WRITE | MAY_EXEC; 368 369 FOREACH_ACL_ENTRY(pa, acl, pe) { 370 switch(pa->e_tag) { 371 case ACL_USER_OBJ: 372 /* (May have been checked already) */ 373 uid = i_uid_into_mnt(mnt_userns, inode); 374 if (uid_eq(uid, current_fsuid())) 375 goto check_perm; 376 break; 377 case ACL_USER: 378 uid = kuid_into_mnt(mnt_userns, pa->e_uid); 379 if (uid_eq(uid, current_fsuid())) 380 goto mask; 381 break; 382 case ACL_GROUP_OBJ: 383 gid = i_gid_into_mnt(mnt_userns, inode); 384 if (in_group_p(gid)) { 385 found = 1; 386 if ((pa->e_perm & want) == want) 387 goto mask; 388 } 389 break; 390 case ACL_GROUP: 391 gid = kgid_into_mnt(mnt_userns, pa->e_gid); 392 if (in_group_p(gid)) { 393 found = 1; 394 if ((pa->e_perm & want) == want) 395 goto mask; 396 } 397 break; 398 case ACL_MASK: 399 break; 400 case ACL_OTHER: 401 if (found) 402 return -EACCES; 403 else 404 goto check_perm; 405 default: 406 return -EIO; 407 } 408 } 409 return -EIO; 410 411 mask: 412 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) { 413 if (mask_obj->e_tag == ACL_MASK) { 414 if ((pa->e_perm & mask_obj->e_perm & want) == want) 415 return 0; 416 return -EACCES; 417 } 418 } 419 420 check_perm: 421 if ((pa->e_perm & want) == want) 422 return 0; 423 return -EACCES; 424 } 425 426 /* 427 * Modify acl when creating a new inode. The caller must ensure the acl is 428 * only referenced once. 429 * 430 * mode_p initially must contain the mode parameter to the open() / creat() 431 * system calls. All permissions that are not granted by the acl are removed. 432 * The permissions in the acl are changed to reflect the mode_p parameter. 433 */ 434 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p) 435 { 436 struct posix_acl_entry *pa, *pe; 437 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 438 umode_t mode = *mode_p; 439 int not_equiv = 0; 440 441 /* assert(atomic_read(acl->a_refcount) == 1); */ 442 443 FOREACH_ACL_ENTRY(pa, acl, pe) { 444 switch(pa->e_tag) { 445 case ACL_USER_OBJ: 446 pa->e_perm &= (mode >> 6) | ~S_IRWXO; 447 mode &= (pa->e_perm << 6) | ~S_IRWXU; 448 break; 449 450 case ACL_USER: 451 case ACL_GROUP: 452 not_equiv = 1; 453 break; 454 455 case ACL_GROUP_OBJ: 456 group_obj = pa; 457 break; 458 459 case ACL_OTHER: 460 pa->e_perm &= mode | ~S_IRWXO; 461 mode &= pa->e_perm | ~S_IRWXO; 462 break; 463 464 case ACL_MASK: 465 mask_obj = pa; 466 not_equiv = 1; 467 break; 468 469 default: 470 return -EIO; 471 } 472 } 473 474 if (mask_obj) { 475 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 476 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG; 477 } else { 478 if (!group_obj) 479 return -EIO; 480 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 481 mode &= (group_obj->e_perm << 3) | ~S_IRWXG; 482 } 483 484 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 485 return not_equiv; 486 } 487 488 /* 489 * Modify the ACL for the chmod syscall. 490 */ 491 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode) 492 { 493 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 494 struct posix_acl_entry *pa, *pe; 495 496 /* assert(atomic_read(acl->a_refcount) == 1); */ 497 498 FOREACH_ACL_ENTRY(pa, acl, pe) { 499 switch(pa->e_tag) { 500 case ACL_USER_OBJ: 501 pa->e_perm = (mode & S_IRWXU) >> 6; 502 break; 503 504 case ACL_USER: 505 case ACL_GROUP: 506 break; 507 508 case ACL_GROUP_OBJ: 509 group_obj = pa; 510 break; 511 512 case ACL_MASK: 513 mask_obj = pa; 514 break; 515 516 case ACL_OTHER: 517 pa->e_perm = (mode & S_IRWXO); 518 break; 519 520 default: 521 return -EIO; 522 } 523 } 524 525 if (mask_obj) { 526 mask_obj->e_perm = (mode & S_IRWXG) >> 3; 527 } else { 528 if (!group_obj) 529 return -EIO; 530 group_obj->e_perm = (mode & S_IRWXG) >> 3; 531 } 532 533 return 0; 534 } 535 536 int 537 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p) 538 { 539 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 540 int err = -ENOMEM; 541 if (clone) { 542 err = posix_acl_create_masq(clone, mode_p); 543 if (err < 0) { 544 posix_acl_release(clone); 545 clone = NULL; 546 } 547 } 548 posix_acl_release(*acl); 549 *acl = clone; 550 return err; 551 } 552 EXPORT_SYMBOL(__posix_acl_create); 553 554 int 555 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode) 556 { 557 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 558 int err = -ENOMEM; 559 if (clone) { 560 err = __posix_acl_chmod_masq(clone, mode); 561 if (err) { 562 posix_acl_release(clone); 563 clone = NULL; 564 } 565 } 566 posix_acl_release(*acl); 567 *acl = clone; 568 return err; 569 } 570 EXPORT_SYMBOL(__posix_acl_chmod); 571 572 /** 573 * posix_acl_chmod - chmod a posix acl 574 * 575 * @mnt_userns: user namespace of the mount @inode was found from 576 * @inode: inode to check permissions on 577 * @mode: the new mode of @inode 578 * 579 * If the inode has been found through an idmapped mount the user namespace of 580 * the vfsmount must be passed through @mnt_userns. This function will then 581 * take care to map the inode according to @mnt_userns before checking 582 * permissions. On non-idmapped mounts or if permission checking is to be 583 * performed on the raw inode simply passs init_user_ns. 584 */ 585 int 586 posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode, 587 umode_t mode) 588 { 589 struct posix_acl *acl; 590 int ret = 0; 591 592 if (!IS_POSIXACL(inode)) 593 return 0; 594 if (!inode->i_op->set_acl) 595 return -EOPNOTSUPP; 596 597 acl = get_acl(inode, ACL_TYPE_ACCESS); 598 if (IS_ERR_OR_NULL(acl)) { 599 if (acl == ERR_PTR(-EOPNOTSUPP)) 600 return 0; 601 return PTR_ERR(acl); 602 } 603 604 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode); 605 if (ret) 606 return ret; 607 ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS); 608 posix_acl_release(acl); 609 return ret; 610 } 611 EXPORT_SYMBOL(posix_acl_chmod); 612 613 int 614 posix_acl_create(struct inode *dir, umode_t *mode, 615 struct posix_acl **default_acl, struct posix_acl **acl) 616 { 617 struct posix_acl *p; 618 struct posix_acl *clone; 619 int ret; 620 621 *acl = NULL; 622 *default_acl = NULL; 623 624 if (S_ISLNK(*mode) || !IS_POSIXACL(dir)) 625 return 0; 626 627 p = get_acl(dir, ACL_TYPE_DEFAULT); 628 if (!p || p == ERR_PTR(-EOPNOTSUPP)) { 629 *mode &= ~current_umask(); 630 return 0; 631 } 632 if (IS_ERR(p)) 633 return PTR_ERR(p); 634 635 ret = -ENOMEM; 636 clone = posix_acl_clone(p, GFP_NOFS); 637 if (!clone) 638 goto err_release; 639 640 ret = posix_acl_create_masq(clone, mode); 641 if (ret < 0) 642 goto err_release_clone; 643 644 if (ret == 0) 645 posix_acl_release(clone); 646 else 647 *acl = clone; 648 649 if (!S_ISDIR(*mode)) 650 posix_acl_release(p); 651 else 652 *default_acl = p; 653 654 return 0; 655 656 err_release_clone: 657 posix_acl_release(clone); 658 err_release: 659 posix_acl_release(p); 660 return ret; 661 } 662 EXPORT_SYMBOL_GPL(posix_acl_create); 663 664 /** 665 * posix_acl_update_mode - update mode in set_acl 666 * @mnt_userns: user namespace of the mount @inode was found from 667 * @inode: target inode 668 * @mode_p: mode (pointer) for update 669 * @acl: acl pointer 670 * 671 * Update the file mode when setting an ACL: compute the new file permission 672 * bits based on the ACL. In addition, if the ACL is equivalent to the new 673 * file mode, set *@acl to NULL to indicate that no ACL should be set. 674 * 675 * As with chmod, clear the setgid bit if the caller is not in the owning group 676 * or capable of CAP_FSETID (see inode_change_ok). 677 * 678 * If the inode has been found through an idmapped mount the user namespace of 679 * the vfsmount must be passed through @mnt_userns. This function will then 680 * take care to map the inode according to @mnt_userns before checking 681 * permissions. On non-idmapped mounts or if permission checking is to be 682 * performed on the raw inode simply passs init_user_ns. 683 * 684 * Called from set_acl inode operations. 685 */ 686 int posix_acl_update_mode(struct user_namespace *mnt_userns, 687 struct inode *inode, umode_t *mode_p, 688 struct posix_acl **acl) 689 { 690 umode_t mode = inode->i_mode; 691 int error; 692 693 error = posix_acl_equiv_mode(*acl, &mode); 694 if (error < 0) 695 return error; 696 if (error == 0) 697 *acl = NULL; 698 if (!in_group_p(i_gid_into_mnt(mnt_userns, inode)) && 699 !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID)) 700 mode &= ~S_ISGID; 701 *mode_p = mode; 702 return 0; 703 } 704 EXPORT_SYMBOL(posix_acl_update_mode); 705 706 /* 707 * Fix up the uids and gids in posix acl extended attributes in place. 708 */ 709 static void posix_acl_fix_xattr_userns( 710 struct user_namespace *to, struct user_namespace *from, 711 struct user_namespace *mnt_userns, 712 void *value, size_t size, bool from_user) 713 { 714 struct posix_acl_xattr_header *header = value; 715 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; 716 int count; 717 kuid_t uid; 718 kgid_t gid; 719 720 if (!value) 721 return; 722 if (size < sizeof(struct posix_acl_xattr_header)) 723 return; 724 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 725 return; 726 727 count = posix_acl_xattr_count(size); 728 if (count < 0) 729 return; 730 if (count == 0) 731 return; 732 733 for (end = entry + count; entry != end; entry++) { 734 switch(le16_to_cpu(entry->e_tag)) { 735 case ACL_USER: 736 uid = make_kuid(from, le32_to_cpu(entry->e_id)); 737 if (from_user) 738 uid = kuid_from_mnt(mnt_userns, uid); 739 else 740 uid = kuid_into_mnt(mnt_userns, uid); 741 entry->e_id = cpu_to_le32(from_kuid(to, uid)); 742 break; 743 case ACL_GROUP: 744 gid = make_kgid(from, le32_to_cpu(entry->e_id)); 745 if (from_user) 746 gid = kgid_from_mnt(mnt_userns, gid); 747 else 748 gid = kgid_into_mnt(mnt_userns, gid); 749 entry->e_id = cpu_to_le32(from_kgid(to, gid)); 750 break; 751 default: 752 break; 753 } 754 } 755 } 756 757 void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns, 758 void *value, size_t size) 759 { 760 struct user_namespace *user_ns = current_user_ns(); 761 if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns)) 762 return; 763 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, mnt_userns, value, 764 size, true); 765 } 766 767 void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns, 768 void *value, size_t size) 769 { 770 struct user_namespace *user_ns = current_user_ns(); 771 if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns)) 772 return; 773 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, mnt_userns, value, 774 size, false); 775 } 776 777 /* 778 * Convert from extended attribute to in-memory representation. 779 */ 780 struct posix_acl * 781 posix_acl_from_xattr(struct user_namespace *user_ns, 782 const void *value, size_t size) 783 { 784 const struct posix_acl_xattr_header *header = value; 785 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end; 786 int count; 787 struct posix_acl *acl; 788 struct posix_acl_entry *acl_e; 789 790 if (!value) 791 return NULL; 792 if (size < sizeof(struct posix_acl_xattr_header)) 793 return ERR_PTR(-EINVAL); 794 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 795 return ERR_PTR(-EOPNOTSUPP); 796 797 count = posix_acl_xattr_count(size); 798 if (count < 0) 799 return ERR_PTR(-EINVAL); 800 if (count == 0) 801 return NULL; 802 803 acl = posix_acl_alloc(count, GFP_NOFS); 804 if (!acl) 805 return ERR_PTR(-ENOMEM); 806 acl_e = acl->a_entries; 807 808 for (end = entry + count; entry != end; acl_e++, entry++) { 809 acl_e->e_tag = le16_to_cpu(entry->e_tag); 810 acl_e->e_perm = le16_to_cpu(entry->e_perm); 811 812 switch(acl_e->e_tag) { 813 case ACL_USER_OBJ: 814 case ACL_GROUP_OBJ: 815 case ACL_MASK: 816 case ACL_OTHER: 817 break; 818 819 case ACL_USER: 820 acl_e->e_uid = 821 make_kuid(user_ns, 822 le32_to_cpu(entry->e_id)); 823 if (!uid_valid(acl_e->e_uid)) 824 goto fail; 825 break; 826 case ACL_GROUP: 827 acl_e->e_gid = 828 make_kgid(user_ns, 829 le32_to_cpu(entry->e_id)); 830 if (!gid_valid(acl_e->e_gid)) 831 goto fail; 832 break; 833 834 default: 835 goto fail; 836 } 837 } 838 return acl; 839 840 fail: 841 posix_acl_release(acl); 842 return ERR_PTR(-EINVAL); 843 } 844 EXPORT_SYMBOL (posix_acl_from_xattr); 845 846 /* 847 * Convert from in-memory to extended attribute representation. 848 */ 849 int 850 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl, 851 void *buffer, size_t size) 852 { 853 struct posix_acl_xattr_header *ext_acl = buffer; 854 struct posix_acl_xattr_entry *ext_entry; 855 int real_size, n; 856 857 real_size = posix_acl_xattr_size(acl->a_count); 858 if (!buffer) 859 return real_size; 860 if (real_size > size) 861 return -ERANGE; 862 863 ext_entry = (void *)(ext_acl + 1); 864 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); 865 866 for (n=0; n < acl->a_count; n++, ext_entry++) { 867 const struct posix_acl_entry *acl_e = &acl->a_entries[n]; 868 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); 869 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); 870 switch(acl_e->e_tag) { 871 case ACL_USER: 872 ext_entry->e_id = 873 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid)); 874 break; 875 case ACL_GROUP: 876 ext_entry->e_id = 877 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid)); 878 break; 879 default: 880 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); 881 break; 882 } 883 } 884 return real_size; 885 } 886 EXPORT_SYMBOL (posix_acl_to_xattr); 887 888 static int 889 posix_acl_xattr_get(const struct xattr_handler *handler, 890 struct dentry *unused, struct inode *inode, 891 const char *name, void *value, size_t size) 892 { 893 struct posix_acl *acl; 894 int error; 895 896 if (!IS_POSIXACL(inode)) 897 return -EOPNOTSUPP; 898 if (S_ISLNK(inode->i_mode)) 899 return -EOPNOTSUPP; 900 901 acl = get_acl(inode, handler->flags); 902 if (IS_ERR(acl)) 903 return PTR_ERR(acl); 904 if (acl == NULL) 905 return -ENODATA; 906 907 error = posix_acl_to_xattr(&init_user_ns, acl, value, size); 908 posix_acl_release(acl); 909 910 return error; 911 } 912 913 int 914 set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode, 915 int type, struct posix_acl *acl) 916 { 917 if (!IS_POSIXACL(inode)) 918 return -EOPNOTSUPP; 919 if (!inode->i_op->set_acl) 920 return -EOPNOTSUPP; 921 922 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) 923 return acl ? -EACCES : 0; 924 if (!inode_owner_or_capable(mnt_userns, inode)) 925 return -EPERM; 926 927 if (acl) { 928 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl); 929 if (ret) 930 return ret; 931 } 932 return inode->i_op->set_acl(mnt_userns, inode, acl, type); 933 } 934 EXPORT_SYMBOL(set_posix_acl); 935 936 static int 937 posix_acl_xattr_set(const struct xattr_handler *handler, 938 struct user_namespace *mnt_userns, 939 struct dentry *unused, struct inode *inode, 940 const char *name, const void *value, size_t size, 941 int flags) 942 { 943 struct posix_acl *acl = NULL; 944 int ret; 945 946 if (value) { 947 acl = posix_acl_from_xattr(&init_user_ns, value, size); 948 if (IS_ERR(acl)) 949 return PTR_ERR(acl); 950 } 951 ret = set_posix_acl(mnt_userns, inode, handler->flags, acl); 952 posix_acl_release(acl); 953 return ret; 954 } 955 956 static bool 957 posix_acl_xattr_list(struct dentry *dentry) 958 { 959 return IS_POSIXACL(d_backing_inode(dentry)); 960 } 961 962 const struct xattr_handler posix_acl_access_xattr_handler = { 963 .name = XATTR_NAME_POSIX_ACL_ACCESS, 964 .flags = ACL_TYPE_ACCESS, 965 .list = posix_acl_xattr_list, 966 .get = posix_acl_xattr_get, 967 .set = posix_acl_xattr_set, 968 }; 969 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler); 970 971 const struct xattr_handler posix_acl_default_xattr_handler = { 972 .name = XATTR_NAME_POSIX_ACL_DEFAULT, 973 .flags = ACL_TYPE_DEFAULT, 974 .list = posix_acl_xattr_list, 975 .get = posix_acl_xattr_get, 976 .set = posix_acl_xattr_set, 977 }; 978 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler); 979 980 int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode, 981 struct posix_acl *acl, int type) 982 { 983 int error; 984 985 if (type == ACL_TYPE_ACCESS) { 986 error = posix_acl_update_mode(mnt_userns, inode, 987 &inode->i_mode, &acl); 988 if (error) 989 return error; 990 } 991 992 inode->i_ctime = current_time(inode); 993 set_cached_acl(inode, type, acl); 994 return 0; 995 } 996 997 int simple_acl_create(struct inode *dir, struct inode *inode) 998 { 999 struct posix_acl *default_acl, *acl; 1000 int error; 1001 1002 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); 1003 if (error) 1004 return error; 1005 1006 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl); 1007 set_cached_acl(inode, ACL_TYPE_ACCESS, acl); 1008 1009 if (default_acl) 1010 posix_acl_release(default_acl); 1011 if (acl) 1012 posix_acl_release(acl); 1013 return 0; 1014 } 1015