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 28 static struct posix_acl **acl_by_type(struct inode *inode, int type) 29 { 30 switch (type) { 31 case ACL_TYPE_ACCESS: 32 return &inode->i_acl; 33 case ACL_TYPE_DEFAULT: 34 return &inode->i_default_acl; 35 default: 36 BUG(); 37 } 38 } 39 40 struct posix_acl *get_cached_acl(struct inode *inode, int type) 41 { 42 struct posix_acl **p = acl_by_type(inode, type); 43 struct posix_acl *acl; 44 45 for (;;) { 46 rcu_read_lock(); 47 acl = rcu_dereference(*p); 48 if (!acl || is_uncached_acl(acl) || 49 refcount_inc_not_zero(&acl->a_refcount)) 50 break; 51 rcu_read_unlock(); 52 cpu_relax(); 53 } 54 rcu_read_unlock(); 55 return acl; 56 } 57 EXPORT_SYMBOL(get_cached_acl); 58 59 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type) 60 { 61 struct posix_acl *acl = rcu_dereference(*acl_by_type(inode, type)); 62 63 if (acl == ACL_DONT_CACHE) { 64 struct posix_acl *ret; 65 66 ret = inode->i_op->get_acl(inode, type, LOOKUP_RCU); 67 if (!IS_ERR(ret)) 68 acl = ret; 69 } 70 71 return acl; 72 } 73 EXPORT_SYMBOL(get_cached_acl_rcu); 74 75 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl) 76 { 77 struct posix_acl **p = acl_by_type(inode, type); 78 struct posix_acl *old; 79 80 old = xchg(p, posix_acl_dup(acl)); 81 if (!is_uncached_acl(old)) 82 posix_acl_release(old); 83 } 84 EXPORT_SYMBOL(set_cached_acl); 85 86 static void __forget_cached_acl(struct posix_acl **p) 87 { 88 struct posix_acl *old; 89 90 old = xchg(p, ACL_NOT_CACHED); 91 if (!is_uncached_acl(old)) 92 posix_acl_release(old); 93 } 94 95 void forget_cached_acl(struct inode *inode, int type) 96 { 97 __forget_cached_acl(acl_by_type(inode, type)); 98 } 99 EXPORT_SYMBOL(forget_cached_acl); 100 101 void forget_all_cached_acls(struct inode *inode) 102 { 103 __forget_cached_acl(&inode->i_acl); 104 __forget_cached_acl(&inode->i_default_acl); 105 } 106 EXPORT_SYMBOL(forget_all_cached_acls); 107 108 struct posix_acl *get_acl(struct inode *inode, int type) 109 { 110 void *sentinel; 111 struct posix_acl **p; 112 struct posix_acl *acl; 113 114 /* 115 * The sentinel is used to detect when another operation like 116 * set_cached_acl() or forget_cached_acl() races with get_acl(). 117 * It is guaranteed that is_uncached_acl(sentinel) is true. 118 */ 119 120 acl = get_cached_acl(inode, type); 121 if (!is_uncached_acl(acl)) 122 return acl; 123 124 if (!IS_POSIXACL(inode)) 125 return NULL; 126 127 sentinel = uncached_acl_sentinel(current); 128 p = acl_by_type(inode, type); 129 130 /* 131 * If the ACL isn't being read yet, set our sentinel. Otherwise, the 132 * current value of the ACL will not be ACL_NOT_CACHED and so our own 133 * sentinel will not be set; another task will update the cache. We 134 * could wait for that other task to complete its job, but it's easier 135 * to just call ->get_acl to fetch the ACL ourself. (This is going to 136 * be an unlikely race.) 137 */ 138 if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED) 139 /* fall through */ ; 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 static 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 } 217 218 /* 219 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise. 220 */ 221 int 222 posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl) 223 { 224 const struct posix_acl_entry *pa, *pe; 225 int state = ACL_USER_OBJ; 226 int needs_mask = 0; 227 228 FOREACH_ACL_ENTRY(pa, acl, pe) { 229 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE)) 230 return -EINVAL; 231 switch (pa->e_tag) { 232 case ACL_USER_OBJ: 233 if (state == ACL_USER_OBJ) { 234 state = ACL_USER; 235 break; 236 } 237 return -EINVAL; 238 239 case ACL_USER: 240 if (state != ACL_USER) 241 return -EINVAL; 242 if (!kuid_has_mapping(user_ns, pa->e_uid)) 243 return -EINVAL; 244 needs_mask = 1; 245 break; 246 247 case ACL_GROUP_OBJ: 248 if (state == ACL_USER) { 249 state = ACL_GROUP; 250 break; 251 } 252 return -EINVAL; 253 254 case ACL_GROUP: 255 if (state != ACL_GROUP) 256 return -EINVAL; 257 if (!kgid_has_mapping(user_ns, pa->e_gid)) 258 return -EINVAL; 259 needs_mask = 1; 260 break; 261 262 case ACL_MASK: 263 if (state != ACL_GROUP) 264 return -EINVAL; 265 state = ACL_OTHER; 266 break; 267 268 case ACL_OTHER: 269 if (state == ACL_OTHER || 270 (state == ACL_GROUP && !needs_mask)) { 271 state = 0; 272 break; 273 } 274 return -EINVAL; 275 276 default: 277 return -EINVAL; 278 } 279 } 280 if (state == 0) 281 return 0; 282 return -EINVAL; 283 } 284 EXPORT_SYMBOL(posix_acl_valid); 285 286 /* 287 * Returns 0 if the acl can be exactly represented in the traditional 288 * file mode permission bits, or else 1. Returns -E... on error. 289 */ 290 int 291 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p) 292 { 293 const struct posix_acl_entry *pa, *pe; 294 umode_t mode = 0; 295 int not_equiv = 0; 296 297 /* 298 * A null ACL can always be presented as mode bits. 299 */ 300 if (!acl) 301 return 0; 302 303 FOREACH_ACL_ENTRY(pa, acl, pe) { 304 switch (pa->e_tag) { 305 case ACL_USER_OBJ: 306 mode |= (pa->e_perm & S_IRWXO) << 6; 307 break; 308 case ACL_GROUP_OBJ: 309 mode |= (pa->e_perm & S_IRWXO) << 3; 310 break; 311 case ACL_OTHER: 312 mode |= pa->e_perm & S_IRWXO; 313 break; 314 case ACL_MASK: 315 mode = (mode & ~S_IRWXG) | 316 ((pa->e_perm & S_IRWXO) << 3); 317 not_equiv = 1; 318 break; 319 case ACL_USER: 320 case ACL_GROUP: 321 not_equiv = 1; 322 break; 323 default: 324 return -EINVAL; 325 } 326 } 327 if (mode_p) 328 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 329 return not_equiv; 330 } 331 EXPORT_SYMBOL(posix_acl_equiv_mode); 332 333 /* 334 * Create an ACL representing the file mode permission bits of an inode. 335 */ 336 struct posix_acl * 337 posix_acl_from_mode(umode_t mode, gfp_t flags) 338 { 339 struct posix_acl *acl = posix_acl_alloc(3, flags); 340 if (!acl) 341 return ERR_PTR(-ENOMEM); 342 343 acl->a_entries[0].e_tag = ACL_USER_OBJ; 344 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6; 345 346 acl->a_entries[1].e_tag = ACL_GROUP_OBJ; 347 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3; 348 349 acl->a_entries[2].e_tag = ACL_OTHER; 350 acl->a_entries[2].e_perm = (mode & S_IRWXO); 351 return acl; 352 } 353 EXPORT_SYMBOL(posix_acl_from_mode); 354 355 /* 356 * Return 0 if current is granted want access to the inode 357 * by the acl. Returns -E... otherwise. 358 */ 359 int 360 posix_acl_permission(struct user_namespace *mnt_userns, struct inode *inode, 361 const struct posix_acl *acl, int want) 362 { 363 const struct posix_acl_entry *pa, *pe, *mask_obj; 364 int found = 0; 365 kuid_t uid; 366 kgid_t gid; 367 368 want &= MAY_READ | MAY_WRITE | MAY_EXEC; 369 370 FOREACH_ACL_ENTRY(pa, acl, pe) { 371 switch(pa->e_tag) { 372 case ACL_USER_OBJ: 373 /* (May have been checked already) */ 374 uid = i_uid_into_mnt(mnt_userns, inode); 375 if (uid_eq(uid, current_fsuid())) 376 goto check_perm; 377 break; 378 case ACL_USER: 379 uid = mapped_kuid_fs(mnt_userns, 380 i_user_ns(inode), 381 pa->e_uid); 382 if (uid_eq(uid, current_fsuid())) 383 goto mask; 384 break; 385 case ACL_GROUP_OBJ: 386 gid = i_gid_into_mnt(mnt_userns, inode); 387 if (in_group_p(gid)) { 388 found = 1; 389 if ((pa->e_perm & want) == want) 390 goto mask; 391 } 392 break; 393 case ACL_GROUP: 394 gid = mapped_kgid_fs(mnt_userns, 395 i_user_ns(inode), 396 pa->e_gid); 397 if (in_group_p(gid)) { 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 (!in_group_p(i_gid_into_mnt(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 void posix_acl_fix_xattr_userns( 715 struct user_namespace *to, struct user_namespace *from, 716 struct user_namespace *mnt_userns, 717 void *value, size_t size, bool from_user) 718 { 719 struct posix_acl_xattr_header *header = value; 720 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; 721 int count; 722 kuid_t uid; 723 kgid_t gid; 724 725 if (!value) 726 return; 727 if (size < sizeof(struct posix_acl_xattr_header)) 728 return; 729 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 730 return; 731 732 count = posix_acl_xattr_count(size); 733 if (count < 0) 734 return; 735 if (count == 0) 736 return; 737 738 for (end = entry + count; entry != end; entry++) { 739 switch(le16_to_cpu(entry->e_tag)) { 740 case ACL_USER: 741 uid = make_kuid(from, le32_to_cpu(entry->e_id)); 742 if (from_user) 743 uid = mapped_kuid_user(mnt_userns, &init_user_ns, uid); 744 else 745 uid = mapped_kuid_fs(mnt_userns, &init_user_ns, uid); 746 entry->e_id = cpu_to_le32(from_kuid(to, uid)); 747 break; 748 case ACL_GROUP: 749 gid = make_kgid(from, le32_to_cpu(entry->e_id)); 750 if (from_user) 751 gid = mapped_kgid_user(mnt_userns, &init_user_ns, gid); 752 else 753 gid = mapped_kgid_fs(mnt_userns, &init_user_ns, gid); 754 entry->e_id = cpu_to_le32(from_kgid(to, gid)); 755 break; 756 default: 757 break; 758 } 759 } 760 } 761 762 void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns, 763 struct inode *inode, 764 void *value, size_t size) 765 { 766 struct user_namespace *user_ns = current_user_ns(); 767 768 /* Leave ids untouched on non-idmapped mounts. */ 769 if (no_idmapping(mnt_userns, i_user_ns(inode))) 770 mnt_userns = &init_user_ns; 771 if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns)) 772 return; 773 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, mnt_userns, value, 774 size, true); 775 } 776 777 void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns, 778 struct inode *inode, 779 void *value, size_t size) 780 { 781 struct user_namespace *user_ns = current_user_ns(); 782 783 /* Leave ids untouched on non-idmapped mounts. */ 784 if (no_idmapping(mnt_userns, i_user_ns(inode))) 785 mnt_userns = &init_user_ns; 786 if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns)) 787 return; 788 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, mnt_userns, value, 789 size, false); 790 } 791 792 /* 793 * Convert from extended attribute to in-memory representation. 794 */ 795 struct posix_acl * 796 posix_acl_from_xattr(struct user_namespace *user_ns, 797 const void *value, size_t size) 798 { 799 const struct posix_acl_xattr_header *header = value; 800 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end; 801 int count; 802 struct posix_acl *acl; 803 struct posix_acl_entry *acl_e; 804 805 if (!value) 806 return NULL; 807 if (size < sizeof(struct posix_acl_xattr_header)) 808 return ERR_PTR(-EINVAL); 809 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 810 return ERR_PTR(-EOPNOTSUPP); 811 812 count = posix_acl_xattr_count(size); 813 if (count < 0) 814 return ERR_PTR(-EINVAL); 815 if (count == 0) 816 return NULL; 817 818 acl = posix_acl_alloc(count, GFP_NOFS); 819 if (!acl) 820 return ERR_PTR(-ENOMEM); 821 acl_e = acl->a_entries; 822 823 for (end = entry + count; entry != end; acl_e++, entry++) { 824 acl_e->e_tag = le16_to_cpu(entry->e_tag); 825 acl_e->e_perm = le16_to_cpu(entry->e_perm); 826 827 switch(acl_e->e_tag) { 828 case ACL_USER_OBJ: 829 case ACL_GROUP_OBJ: 830 case ACL_MASK: 831 case ACL_OTHER: 832 break; 833 834 case ACL_USER: 835 acl_e->e_uid = 836 make_kuid(user_ns, 837 le32_to_cpu(entry->e_id)); 838 if (!uid_valid(acl_e->e_uid)) 839 goto fail; 840 break; 841 case ACL_GROUP: 842 acl_e->e_gid = 843 make_kgid(user_ns, 844 le32_to_cpu(entry->e_id)); 845 if (!gid_valid(acl_e->e_gid)) 846 goto fail; 847 break; 848 849 default: 850 goto fail; 851 } 852 } 853 return acl; 854 855 fail: 856 posix_acl_release(acl); 857 return ERR_PTR(-EINVAL); 858 } 859 EXPORT_SYMBOL (posix_acl_from_xattr); 860 861 /* 862 * Convert from in-memory to extended attribute representation. 863 */ 864 int 865 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl, 866 void *buffer, size_t size) 867 { 868 struct posix_acl_xattr_header *ext_acl = buffer; 869 struct posix_acl_xattr_entry *ext_entry; 870 int real_size, n; 871 872 real_size = posix_acl_xattr_size(acl->a_count); 873 if (!buffer) 874 return real_size; 875 if (real_size > size) 876 return -ERANGE; 877 878 ext_entry = (void *)(ext_acl + 1); 879 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); 880 881 for (n=0; n < acl->a_count; n++, ext_entry++) { 882 const struct posix_acl_entry *acl_e = &acl->a_entries[n]; 883 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); 884 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); 885 switch(acl_e->e_tag) { 886 case ACL_USER: 887 ext_entry->e_id = 888 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid)); 889 break; 890 case ACL_GROUP: 891 ext_entry->e_id = 892 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid)); 893 break; 894 default: 895 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); 896 break; 897 } 898 } 899 return real_size; 900 } 901 EXPORT_SYMBOL (posix_acl_to_xattr); 902 903 static int 904 posix_acl_xattr_get(const struct xattr_handler *handler, 905 struct dentry *unused, struct inode *inode, 906 const char *name, void *value, size_t size) 907 { 908 struct posix_acl *acl; 909 int error; 910 911 if (!IS_POSIXACL(inode)) 912 return -EOPNOTSUPP; 913 if (S_ISLNK(inode->i_mode)) 914 return -EOPNOTSUPP; 915 916 acl = get_acl(inode, handler->flags); 917 if (IS_ERR(acl)) 918 return PTR_ERR(acl); 919 if (acl == NULL) 920 return -ENODATA; 921 922 error = posix_acl_to_xattr(&init_user_ns, acl, value, size); 923 posix_acl_release(acl); 924 925 return error; 926 } 927 928 int 929 set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode, 930 int type, struct posix_acl *acl) 931 { 932 if (!IS_POSIXACL(inode)) 933 return -EOPNOTSUPP; 934 if (!inode->i_op->set_acl) 935 return -EOPNOTSUPP; 936 937 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) 938 return acl ? -EACCES : 0; 939 if (!inode_owner_or_capable(mnt_userns, inode)) 940 return -EPERM; 941 942 if (acl) { 943 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl); 944 if (ret) 945 return ret; 946 } 947 return inode->i_op->set_acl(mnt_userns, inode, acl, type); 948 } 949 EXPORT_SYMBOL(set_posix_acl); 950 951 static int 952 posix_acl_xattr_set(const struct xattr_handler *handler, 953 struct user_namespace *mnt_userns, 954 struct dentry *unused, struct inode *inode, 955 const char *name, const void *value, size_t size, 956 int flags) 957 { 958 struct posix_acl *acl = NULL; 959 int ret; 960 961 if (value) { 962 acl = posix_acl_from_xattr(&init_user_ns, value, size); 963 if (IS_ERR(acl)) 964 return PTR_ERR(acl); 965 } 966 ret = set_posix_acl(mnt_userns, inode, handler->flags, acl); 967 posix_acl_release(acl); 968 return ret; 969 } 970 971 static bool 972 posix_acl_xattr_list(struct dentry *dentry) 973 { 974 return IS_POSIXACL(d_backing_inode(dentry)); 975 } 976 977 const struct xattr_handler posix_acl_access_xattr_handler = { 978 .name = XATTR_NAME_POSIX_ACL_ACCESS, 979 .flags = ACL_TYPE_ACCESS, 980 .list = posix_acl_xattr_list, 981 .get = posix_acl_xattr_get, 982 .set = posix_acl_xattr_set, 983 }; 984 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler); 985 986 const struct xattr_handler posix_acl_default_xattr_handler = { 987 .name = XATTR_NAME_POSIX_ACL_DEFAULT, 988 .flags = ACL_TYPE_DEFAULT, 989 .list = posix_acl_xattr_list, 990 .get = posix_acl_xattr_get, 991 .set = posix_acl_xattr_set, 992 }; 993 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler); 994 995 int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode, 996 struct posix_acl *acl, int type) 997 { 998 int error; 999 1000 if (type == ACL_TYPE_ACCESS) { 1001 error = posix_acl_update_mode(mnt_userns, inode, 1002 &inode->i_mode, &acl); 1003 if (error) 1004 return error; 1005 } 1006 1007 inode->i_ctime = current_time(inode); 1008 set_cached_acl(inode, type, acl); 1009 return 0; 1010 } 1011 1012 int simple_acl_create(struct inode *dir, struct inode *inode) 1013 { 1014 struct posix_acl *default_acl, *acl; 1015 int error; 1016 1017 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); 1018 if (error) 1019 return error; 1020 1021 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl); 1022 set_cached_acl(inode, ACL_TYPE_ACCESS, acl); 1023 1024 if (default_acl) 1025 posix_acl_release(default_acl); 1026 if (acl) 1027 posix_acl_release(acl); 1028 return 0; 1029 } 1030