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 acl_by_type(struct inode * inode,int type)26 static struct posix_acl **acl_by_type(struct inode *inode, int type) 27 { 28 switch (type) { 29 case ACL_TYPE_ACCESS: 30 return &inode->i_acl; 31 case ACL_TYPE_DEFAULT: 32 return &inode->i_default_acl; 33 default: 34 BUG(); 35 } 36 } 37 get_cached_acl(struct inode * inode,int type)38 struct posix_acl *get_cached_acl(struct inode *inode, int type) 39 { 40 struct posix_acl **p = acl_by_type(inode, type); 41 struct posix_acl *acl; 42 43 for (;;) { 44 rcu_read_lock(); 45 acl = rcu_dereference(*p); 46 if (!acl || is_uncached_acl(acl) || 47 refcount_inc_not_zero(&acl->a_refcount)) 48 break; 49 rcu_read_unlock(); 50 cpu_relax(); 51 } 52 rcu_read_unlock(); 53 return acl; 54 } 55 EXPORT_SYMBOL(get_cached_acl); 56 get_cached_acl_rcu(struct inode * inode,int type)57 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type) 58 { 59 return rcu_dereference(*acl_by_type(inode, type)); 60 } 61 EXPORT_SYMBOL(get_cached_acl_rcu); 62 set_cached_acl(struct inode * inode,int type,struct posix_acl * acl)63 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl) 64 { 65 struct posix_acl **p = acl_by_type(inode, type); 66 struct posix_acl *old; 67 68 old = xchg(p, posix_acl_dup(acl)); 69 if (!is_uncached_acl(old)) 70 posix_acl_release(old); 71 } 72 EXPORT_SYMBOL(set_cached_acl); 73 __forget_cached_acl(struct posix_acl ** p)74 static void __forget_cached_acl(struct posix_acl **p) 75 { 76 struct posix_acl *old; 77 78 old = xchg(p, ACL_NOT_CACHED); 79 if (!is_uncached_acl(old)) 80 posix_acl_release(old); 81 } 82 forget_cached_acl(struct inode * inode,int type)83 void forget_cached_acl(struct inode *inode, int type) 84 { 85 __forget_cached_acl(acl_by_type(inode, type)); 86 } 87 EXPORT_SYMBOL(forget_cached_acl); 88 forget_all_cached_acls(struct inode * inode)89 void forget_all_cached_acls(struct inode *inode) 90 { 91 __forget_cached_acl(&inode->i_acl); 92 __forget_cached_acl(&inode->i_default_acl); 93 } 94 EXPORT_SYMBOL(forget_all_cached_acls); 95 get_acl(struct inode * inode,int type)96 struct posix_acl *get_acl(struct inode *inode, int type) 97 { 98 void *sentinel; 99 struct posix_acl **p; 100 struct posix_acl *acl; 101 102 /* 103 * The sentinel is used to detect when another operation like 104 * set_cached_acl() or forget_cached_acl() races with get_acl(). 105 * It is guaranteed that is_uncached_acl(sentinel) is true. 106 */ 107 108 acl = get_cached_acl(inode, type); 109 if (!is_uncached_acl(acl)) 110 return acl; 111 112 if (!IS_POSIXACL(inode)) 113 return NULL; 114 115 sentinel = uncached_acl_sentinel(current); 116 p = acl_by_type(inode, type); 117 118 /* 119 * If the ACL isn't being read yet, set our sentinel. Otherwise, the 120 * current value of the ACL will not be ACL_NOT_CACHED and so our own 121 * sentinel will not be set; another task will update the cache. We 122 * could wait for that other task to complete its job, but it's easier 123 * to just call ->get_acl to fetch the ACL ourself. (This is going to 124 * be an unlikely race.) 125 */ 126 if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED) 127 /* fall through */ ; 128 129 /* 130 * Normally, the ACL returned by ->get_acl will be cached. 131 * A filesystem can prevent that by calling 132 * forget_cached_acl(inode, type) in ->get_acl. 133 * 134 * If the filesystem doesn't have a get_acl() function at all, we'll 135 * just create the negative cache entry. 136 */ 137 if (!inode->i_op->get_acl) { 138 set_cached_acl(inode, type, NULL); 139 return NULL; 140 } 141 acl = inode->i_op->get_acl(inode, type); 142 143 if (IS_ERR(acl)) { 144 /* 145 * Remove our sentinel so that we don't block future attempts 146 * to cache the ACL. 147 */ 148 cmpxchg(p, sentinel, ACL_NOT_CACHED); 149 return acl; 150 } 151 152 /* 153 * Cache the result, but only if our sentinel is still in place. 154 */ 155 posix_acl_dup(acl); 156 if (unlikely(cmpxchg(p, sentinel, acl) != sentinel)) 157 posix_acl_release(acl); 158 return acl; 159 } 160 EXPORT_SYMBOL(get_acl); 161 162 /* 163 * Init a fresh posix_acl 164 */ 165 void posix_acl_init(struct posix_acl * acl,int count)166 posix_acl_init(struct posix_acl *acl, int count) 167 { 168 refcount_set(&acl->a_refcount, 1); 169 acl->a_count = count; 170 } 171 EXPORT_SYMBOL(posix_acl_init); 172 173 /* 174 * Allocate a new ACL with the specified number of entries. 175 */ 176 struct posix_acl * posix_acl_alloc(int count,gfp_t flags)177 posix_acl_alloc(int count, gfp_t flags) 178 { 179 const size_t size = sizeof(struct posix_acl) + 180 count * sizeof(struct posix_acl_entry); 181 struct posix_acl *acl = kmalloc(size, flags); 182 if (acl) 183 posix_acl_init(acl, count); 184 return acl; 185 } 186 EXPORT_SYMBOL(posix_acl_alloc); 187 188 /* 189 * Clone an ACL. 190 */ 191 static struct posix_acl * posix_acl_clone(const struct posix_acl * acl,gfp_t flags)192 posix_acl_clone(const struct posix_acl *acl, gfp_t flags) 193 { 194 struct posix_acl *clone = NULL; 195 196 if (acl) { 197 int size = sizeof(struct posix_acl) + acl->a_count * 198 sizeof(struct posix_acl_entry); 199 clone = kmemdup(acl, size, flags); 200 if (clone) 201 refcount_set(&clone->a_refcount, 1); 202 } 203 return clone; 204 } 205 206 /* 207 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise. 208 */ 209 int posix_acl_valid(struct user_namespace * user_ns,const struct posix_acl * acl)210 posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl) 211 { 212 const struct posix_acl_entry *pa, *pe; 213 int state = ACL_USER_OBJ; 214 int needs_mask = 0; 215 216 FOREACH_ACL_ENTRY(pa, acl, pe) { 217 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE)) 218 return -EINVAL; 219 switch (pa->e_tag) { 220 case ACL_USER_OBJ: 221 if (state == ACL_USER_OBJ) { 222 state = ACL_USER; 223 break; 224 } 225 return -EINVAL; 226 227 case ACL_USER: 228 if (state != ACL_USER) 229 return -EINVAL; 230 if (!kuid_has_mapping(user_ns, pa->e_uid)) 231 return -EINVAL; 232 needs_mask = 1; 233 break; 234 235 case ACL_GROUP_OBJ: 236 if (state == ACL_USER) { 237 state = ACL_GROUP; 238 break; 239 } 240 return -EINVAL; 241 242 case ACL_GROUP: 243 if (state != ACL_GROUP) 244 return -EINVAL; 245 if (!kgid_has_mapping(user_ns, pa->e_gid)) 246 return -EINVAL; 247 needs_mask = 1; 248 break; 249 250 case ACL_MASK: 251 if (state != ACL_GROUP) 252 return -EINVAL; 253 state = ACL_OTHER; 254 break; 255 256 case ACL_OTHER: 257 if (state == ACL_OTHER || 258 (state == ACL_GROUP && !needs_mask)) { 259 state = 0; 260 break; 261 } 262 return -EINVAL; 263 264 default: 265 return -EINVAL; 266 } 267 } 268 if (state == 0) 269 return 0; 270 return -EINVAL; 271 } 272 EXPORT_SYMBOL(posix_acl_valid); 273 274 /* 275 * Returns 0 if the acl can be exactly represented in the traditional 276 * file mode permission bits, or else 1. Returns -E... on error. 277 */ 278 int posix_acl_equiv_mode(const struct posix_acl * acl,umode_t * mode_p)279 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p) 280 { 281 const struct posix_acl_entry *pa, *pe; 282 umode_t mode = 0; 283 int not_equiv = 0; 284 285 /* 286 * A null ACL can always be presented as mode bits. 287 */ 288 if (!acl) 289 return 0; 290 291 FOREACH_ACL_ENTRY(pa, acl, pe) { 292 switch (pa->e_tag) { 293 case ACL_USER_OBJ: 294 mode |= (pa->e_perm & S_IRWXO) << 6; 295 break; 296 case ACL_GROUP_OBJ: 297 mode |= (pa->e_perm & S_IRWXO) << 3; 298 break; 299 case ACL_OTHER: 300 mode |= pa->e_perm & S_IRWXO; 301 break; 302 case ACL_MASK: 303 mode = (mode & ~S_IRWXG) | 304 ((pa->e_perm & S_IRWXO) << 3); 305 not_equiv = 1; 306 break; 307 case ACL_USER: 308 case ACL_GROUP: 309 not_equiv = 1; 310 break; 311 default: 312 return -EINVAL; 313 } 314 } 315 if (mode_p) 316 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 317 return not_equiv; 318 } 319 EXPORT_SYMBOL(posix_acl_equiv_mode); 320 321 /* 322 * Create an ACL representing the file mode permission bits of an inode. 323 */ 324 struct posix_acl * posix_acl_from_mode(umode_t mode,gfp_t flags)325 posix_acl_from_mode(umode_t mode, gfp_t flags) 326 { 327 struct posix_acl *acl = posix_acl_alloc(3, flags); 328 if (!acl) 329 return ERR_PTR(-ENOMEM); 330 331 acl->a_entries[0].e_tag = ACL_USER_OBJ; 332 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6; 333 334 acl->a_entries[1].e_tag = ACL_GROUP_OBJ; 335 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3; 336 337 acl->a_entries[2].e_tag = ACL_OTHER; 338 acl->a_entries[2].e_perm = (mode & S_IRWXO); 339 return acl; 340 } 341 EXPORT_SYMBOL(posix_acl_from_mode); 342 343 /* 344 * Return 0 if current is granted want access to the inode 345 * by the acl. Returns -E... otherwise. 346 */ 347 int posix_acl_permission(struct inode * inode,const struct posix_acl * acl,int want)348 posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want) 349 { 350 const struct posix_acl_entry *pa, *pe, *mask_obj; 351 int found = 0; 352 353 want &= MAY_READ | MAY_WRITE | MAY_EXEC; 354 355 FOREACH_ACL_ENTRY(pa, acl, pe) { 356 switch(pa->e_tag) { 357 case ACL_USER_OBJ: 358 /* (May have been checked already) */ 359 if (uid_eq(inode->i_uid, current_fsuid())) 360 goto check_perm; 361 break; 362 case ACL_USER: 363 if (uid_eq(pa->e_uid, current_fsuid())) 364 goto mask; 365 break; 366 case ACL_GROUP_OBJ: 367 if (in_group_p(inode->i_gid)) { 368 found = 1; 369 if ((pa->e_perm & want) == want) 370 goto mask; 371 } 372 break; 373 case ACL_GROUP: 374 if (in_group_p(pa->e_gid)) { 375 found = 1; 376 if ((pa->e_perm & want) == want) 377 goto mask; 378 } 379 break; 380 case ACL_MASK: 381 break; 382 case ACL_OTHER: 383 if (found) 384 return -EACCES; 385 else 386 goto check_perm; 387 default: 388 return -EIO; 389 } 390 } 391 return -EIO; 392 393 mask: 394 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) { 395 if (mask_obj->e_tag == ACL_MASK) { 396 if ((pa->e_perm & mask_obj->e_perm & want) == want) 397 return 0; 398 return -EACCES; 399 } 400 } 401 402 check_perm: 403 if ((pa->e_perm & want) == want) 404 return 0; 405 return -EACCES; 406 } 407 408 /* 409 * Modify acl when creating a new inode. The caller must ensure the acl is 410 * only referenced once. 411 * 412 * mode_p initially must contain the mode parameter to the open() / creat() 413 * system calls. All permissions that are not granted by the acl are removed. 414 * The permissions in the acl are changed to reflect the mode_p parameter. 415 */ posix_acl_create_masq(struct posix_acl * acl,umode_t * mode_p)416 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p) 417 { 418 struct posix_acl_entry *pa, *pe; 419 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 420 umode_t mode = *mode_p; 421 int not_equiv = 0; 422 423 /* assert(atomic_read(acl->a_refcount) == 1); */ 424 425 FOREACH_ACL_ENTRY(pa, acl, pe) { 426 switch(pa->e_tag) { 427 case ACL_USER_OBJ: 428 pa->e_perm &= (mode >> 6) | ~S_IRWXO; 429 mode &= (pa->e_perm << 6) | ~S_IRWXU; 430 break; 431 432 case ACL_USER: 433 case ACL_GROUP: 434 not_equiv = 1; 435 break; 436 437 case ACL_GROUP_OBJ: 438 group_obj = pa; 439 break; 440 441 case ACL_OTHER: 442 pa->e_perm &= mode | ~S_IRWXO; 443 mode &= pa->e_perm | ~S_IRWXO; 444 break; 445 446 case ACL_MASK: 447 mask_obj = pa; 448 not_equiv = 1; 449 break; 450 451 default: 452 return -EIO; 453 } 454 } 455 456 if (mask_obj) { 457 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 458 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG; 459 } else { 460 if (!group_obj) 461 return -EIO; 462 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO; 463 mode &= (group_obj->e_perm << 3) | ~S_IRWXG; 464 } 465 466 *mode_p = (*mode_p & ~S_IRWXUGO) | mode; 467 return not_equiv; 468 } 469 470 /* 471 * Modify the ACL for the chmod syscall. 472 */ __posix_acl_chmod_masq(struct posix_acl * acl,umode_t mode)473 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode) 474 { 475 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; 476 struct posix_acl_entry *pa, *pe; 477 478 /* assert(atomic_read(acl->a_refcount) == 1); */ 479 480 FOREACH_ACL_ENTRY(pa, acl, pe) { 481 switch(pa->e_tag) { 482 case ACL_USER_OBJ: 483 pa->e_perm = (mode & S_IRWXU) >> 6; 484 break; 485 486 case ACL_USER: 487 case ACL_GROUP: 488 break; 489 490 case ACL_GROUP_OBJ: 491 group_obj = pa; 492 break; 493 494 case ACL_MASK: 495 mask_obj = pa; 496 break; 497 498 case ACL_OTHER: 499 pa->e_perm = (mode & S_IRWXO); 500 break; 501 502 default: 503 return -EIO; 504 } 505 } 506 507 if (mask_obj) { 508 mask_obj->e_perm = (mode & S_IRWXG) >> 3; 509 } else { 510 if (!group_obj) 511 return -EIO; 512 group_obj->e_perm = (mode & S_IRWXG) >> 3; 513 } 514 515 return 0; 516 } 517 518 int __posix_acl_create(struct posix_acl ** acl,gfp_t gfp,umode_t * mode_p)519 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p) 520 { 521 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 522 int err = -ENOMEM; 523 if (clone) { 524 err = posix_acl_create_masq(clone, mode_p); 525 if (err < 0) { 526 posix_acl_release(clone); 527 clone = NULL; 528 } 529 } 530 posix_acl_release(*acl); 531 *acl = clone; 532 return err; 533 } 534 EXPORT_SYMBOL(__posix_acl_create); 535 536 int __posix_acl_chmod(struct posix_acl ** acl,gfp_t gfp,umode_t mode)537 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode) 538 { 539 struct posix_acl *clone = posix_acl_clone(*acl, gfp); 540 int err = -ENOMEM; 541 if (clone) { 542 err = __posix_acl_chmod_masq(clone, mode); 543 if (err) { 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_chmod); 553 554 int posix_acl_chmod(struct inode * inode,umode_t mode)555 posix_acl_chmod(struct inode *inode, umode_t mode) 556 { 557 struct posix_acl *acl; 558 int ret = 0; 559 560 if (!IS_POSIXACL(inode)) 561 return 0; 562 if (!inode->i_op->set_acl) 563 return -EOPNOTSUPP; 564 565 acl = get_acl(inode, ACL_TYPE_ACCESS); 566 if (IS_ERR_OR_NULL(acl)) { 567 if (acl == ERR_PTR(-EOPNOTSUPP)) 568 return 0; 569 return PTR_ERR(acl); 570 } 571 572 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode); 573 if (ret) 574 return ret; 575 ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS); 576 posix_acl_release(acl); 577 return ret; 578 } 579 EXPORT_SYMBOL(posix_acl_chmod); 580 581 int posix_acl_create(struct inode * dir,umode_t * mode,struct posix_acl ** default_acl,struct posix_acl ** acl)582 posix_acl_create(struct inode *dir, umode_t *mode, 583 struct posix_acl **default_acl, struct posix_acl **acl) 584 { 585 struct posix_acl *p; 586 struct posix_acl *clone; 587 int ret; 588 589 *acl = NULL; 590 *default_acl = NULL; 591 592 if (S_ISLNK(*mode) || !IS_POSIXACL(dir)) 593 return 0; 594 595 p = get_acl(dir, ACL_TYPE_DEFAULT); 596 if (!p || p == ERR_PTR(-EOPNOTSUPP)) { 597 *mode &= ~current_umask(); 598 return 0; 599 } 600 if (IS_ERR(p)) 601 return PTR_ERR(p); 602 603 ret = -ENOMEM; 604 clone = posix_acl_clone(p, GFP_NOFS); 605 if (!clone) 606 goto err_release; 607 608 ret = posix_acl_create_masq(clone, mode); 609 if (ret < 0) 610 goto err_release_clone; 611 612 if (ret == 0) 613 posix_acl_release(clone); 614 else 615 *acl = clone; 616 617 if (!S_ISDIR(*mode)) 618 posix_acl_release(p); 619 else 620 *default_acl = p; 621 622 return 0; 623 624 err_release_clone: 625 posix_acl_release(clone); 626 err_release: 627 posix_acl_release(p); 628 return ret; 629 } 630 EXPORT_SYMBOL_GPL(posix_acl_create); 631 632 /** 633 * posix_acl_update_mode - update mode in set_acl 634 * @inode: target inode 635 * @mode_p: mode (pointer) for update 636 * @acl: acl pointer 637 * 638 * Update the file mode when setting an ACL: compute the new file permission 639 * bits based on the ACL. In addition, if the ACL is equivalent to the new 640 * file mode, set *@acl to NULL to indicate that no ACL should be set. 641 * 642 * As with chmod, clear the setgid bit if the caller is not in the owning group 643 * or capable of CAP_FSETID (see inode_change_ok). 644 * 645 * Called from set_acl inode operations. 646 */ posix_acl_update_mode(struct inode * inode,umode_t * mode_p,struct posix_acl ** acl)647 int posix_acl_update_mode(struct inode *inode, umode_t *mode_p, 648 struct posix_acl **acl) 649 { 650 umode_t mode = inode->i_mode; 651 int error; 652 653 error = posix_acl_equiv_mode(*acl, &mode); 654 if (error < 0) 655 return error; 656 if (error == 0) 657 *acl = NULL; 658 if (!in_group_p(inode->i_gid) && 659 !capable_wrt_inode_uidgid(inode, CAP_FSETID)) 660 mode &= ~S_ISGID; 661 *mode_p = mode; 662 return 0; 663 } 664 EXPORT_SYMBOL(posix_acl_update_mode); 665 666 /* 667 * Fix up the uids and gids in posix acl extended attributes in place. 668 */ posix_acl_fix_xattr_userns(struct user_namespace * to,struct user_namespace * from,void * value,size_t size)669 static void posix_acl_fix_xattr_userns( 670 struct user_namespace *to, struct user_namespace *from, 671 void *value, size_t size) 672 { 673 struct posix_acl_xattr_header *header = value; 674 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; 675 int count; 676 kuid_t uid; 677 kgid_t gid; 678 679 if (!value) 680 return; 681 if (size < sizeof(struct posix_acl_xattr_header)) 682 return; 683 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 684 return; 685 686 count = posix_acl_xattr_count(size); 687 if (count < 0) 688 return; 689 if (count == 0) 690 return; 691 692 for (end = entry + count; entry != end; entry++) { 693 switch(le16_to_cpu(entry->e_tag)) { 694 case ACL_USER: 695 uid = make_kuid(from, le32_to_cpu(entry->e_id)); 696 entry->e_id = cpu_to_le32(from_kuid(to, uid)); 697 break; 698 case ACL_GROUP: 699 gid = make_kgid(from, le32_to_cpu(entry->e_id)); 700 entry->e_id = cpu_to_le32(from_kgid(to, gid)); 701 break; 702 default: 703 break; 704 } 705 } 706 } 707 posix_acl_fix_xattr_from_user(void * value,size_t size)708 void posix_acl_fix_xattr_from_user(void *value, size_t size) 709 { 710 struct user_namespace *user_ns = current_user_ns(); 711 if (user_ns == &init_user_ns) 712 return; 713 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size); 714 } 715 posix_acl_fix_xattr_to_user(void * value,size_t size)716 void posix_acl_fix_xattr_to_user(void *value, size_t size) 717 { 718 struct user_namespace *user_ns = current_user_ns(); 719 if (user_ns == &init_user_ns) 720 return; 721 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size); 722 } 723 724 /* 725 * Convert from extended attribute to in-memory representation. 726 */ 727 struct posix_acl * posix_acl_from_xattr(struct user_namespace * user_ns,const void * value,size_t size)728 posix_acl_from_xattr(struct user_namespace *user_ns, 729 const void *value, size_t size) 730 { 731 const struct posix_acl_xattr_header *header = value; 732 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end; 733 int count; 734 struct posix_acl *acl; 735 struct posix_acl_entry *acl_e; 736 737 if (!value) 738 return NULL; 739 if (size < sizeof(struct posix_acl_xattr_header)) 740 return ERR_PTR(-EINVAL); 741 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) 742 return ERR_PTR(-EOPNOTSUPP); 743 744 count = posix_acl_xattr_count(size); 745 if (count < 0) 746 return ERR_PTR(-EINVAL); 747 if (count == 0) 748 return NULL; 749 750 acl = posix_acl_alloc(count, GFP_NOFS); 751 if (!acl) 752 return ERR_PTR(-ENOMEM); 753 acl_e = acl->a_entries; 754 755 for (end = entry + count; entry != end; acl_e++, entry++) { 756 acl_e->e_tag = le16_to_cpu(entry->e_tag); 757 acl_e->e_perm = le16_to_cpu(entry->e_perm); 758 759 switch(acl_e->e_tag) { 760 case ACL_USER_OBJ: 761 case ACL_GROUP_OBJ: 762 case ACL_MASK: 763 case ACL_OTHER: 764 break; 765 766 case ACL_USER: 767 acl_e->e_uid = 768 make_kuid(user_ns, 769 le32_to_cpu(entry->e_id)); 770 if (!uid_valid(acl_e->e_uid)) 771 goto fail; 772 break; 773 case ACL_GROUP: 774 acl_e->e_gid = 775 make_kgid(user_ns, 776 le32_to_cpu(entry->e_id)); 777 if (!gid_valid(acl_e->e_gid)) 778 goto fail; 779 break; 780 781 default: 782 goto fail; 783 } 784 } 785 return acl; 786 787 fail: 788 posix_acl_release(acl); 789 return ERR_PTR(-EINVAL); 790 } 791 EXPORT_SYMBOL (posix_acl_from_xattr); 792 793 /* 794 * Convert from in-memory to extended attribute representation. 795 */ 796 int posix_acl_to_xattr(struct user_namespace * user_ns,const struct posix_acl * acl,void * buffer,size_t size)797 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl, 798 void *buffer, size_t size) 799 { 800 struct posix_acl_xattr_header *ext_acl = buffer; 801 struct posix_acl_xattr_entry *ext_entry; 802 int real_size, n; 803 804 real_size = posix_acl_xattr_size(acl->a_count); 805 if (!buffer) 806 return real_size; 807 if (real_size > size) 808 return -ERANGE; 809 810 ext_entry = (void *)(ext_acl + 1); 811 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); 812 813 for (n=0; n < acl->a_count; n++, ext_entry++) { 814 const struct posix_acl_entry *acl_e = &acl->a_entries[n]; 815 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); 816 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); 817 switch(acl_e->e_tag) { 818 case ACL_USER: 819 ext_entry->e_id = 820 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid)); 821 break; 822 case ACL_GROUP: 823 ext_entry->e_id = 824 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid)); 825 break; 826 default: 827 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); 828 break; 829 } 830 } 831 return real_size; 832 } 833 EXPORT_SYMBOL (posix_acl_to_xattr); 834 835 static int posix_acl_xattr_get(const struct xattr_handler * handler,struct dentry * unused,struct inode * inode,const char * name,void * value,size_t size)836 posix_acl_xattr_get(const struct xattr_handler *handler, 837 struct dentry *unused, struct inode *inode, 838 const char *name, void *value, size_t size) 839 { 840 struct posix_acl *acl; 841 int error; 842 843 if (!IS_POSIXACL(inode)) 844 return -EOPNOTSUPP; 845 if (S_ISLNK(inode->i_mode)) 846 return -EOPNOTSUPP; 847 848 acl = get_acl(inode, handler->flags); 849 if (IS_ERR(acl)) 850 return PTR_ERR(acl); 851 if (acl == NULL) 852 return -ENODATA; 853 854 error = posix_acl_to_xattr(&init_user_ns, acl, value, size); 855 posix_acl_release(acl); 856 857 return error; 858 } 859 860 int set_posix_acl(struct inode * inode,int type,struct posix_acl * acl)861 set_posix_acl(struct inode *inode, int type, struct posix_acl *acl) 862 { 863 if (!IS_POSIXACL(inode)) 864 return -EOPNOTSUPP; 865 if (!inode->i_op->set_acl) 866 return -EOPNOTSUPP; 867 868 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) 869 return acl ? -EACCES : 0; 870 if (!inode_owner_or_capable(inode)) 871 return -EPERM; 872 873 if (acl) { 874 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl); 875 if (ret) 876 return ret; 877 } 878 return inode->i_op->set_acl(inode, acl, type); 879 } 880 EXPORT_SYMBOL(set_posix_acl); 881 882 static int posix_acl_xattr_set(const struct xattr_handler * handler,struct dentry * unused,struct inode * inode,const char * name,const void * value,size_t size,int flags)883 posix_acl_xattr_set(const struct xattr_handler *handler, 884 struct dentry *unused, struct inode *inode, 885 const char *name, const void *value, 886 size_t size, int flags) 887 { 888 struct posix_acl *acl = NULL; 889 int ret; 890 891 if (value) { 892 acl = posix_acl_from_xattr(&init_user_ns, value, size); 893 if (IS_ERR(acl)) 894 return PTR_ERR(acl); 895 } 896 ret = set_posix_acl(inode, handler->flags, acl); 897 posix_acl_release(acl); 898 return ret; 899 } 900 901 static bool posix_acl_xattr_list(struct dentry * dentry)902 posix_acl_xattr_list(struct dentry *dentry) 903 { 904 return IS_POSIXACL(d_backing_inode(dentry)); 905 } 906 907 const struct xattr_handler posix_acl_access_xattr_handler = { 908 .name = XATTR_NAME_POSIX_ACL_ACCESS, 909 .flags = ACL_TYPE_ACCESS, 910 .list = posix_acl_xattr_list, 911 .get = posix_acl_xattr_get, 912 .set = posix_acl_xattr_set, 913 }; 914 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler); 915 916 const struct xattr_handler posix_acl_default_xattr_handler = { 917 .name = XATTR_NAME_POSIX_ACL_DEFAULT, 918 .flags = ACL_TYPE_DEFAULT, 919 .list = posix_acl_xattr_list, 920 .get = posix_acl_xattr_get, 921 .set = posix_acl_xattr_set, 922 }; 923 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler); 924 simple_set_acl(struct inode * inode,struct posix_acl * acl,int type)925 int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type) 926 { 927 int error; 928 929 if (type == ACL_TYPE_ACCESS) { 930 error = posix_acl_update_mode(inode, 931 &inode->i_mode, &acl); 932 if (error) 933 return error; 934 } 935 936 inode->i_ctime = current_time(inode); 937 set_cached_acl(inode, type, acl); 938 return 0; 939 } 940 simple_acl_create(struct inode * dir,struct inode * inode)941 int simple_acl_create(struct inode *dir, struct inode *inode) 942 { 943 struct posix_acl *default_acl, *acl; 944 int error; 945 946 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); 947 if (error) 948 return error; 949 950 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl); 951 set_cached_acl(inode, ACL_TYPE_ACCESS, acl); 952 953 if (default_acl) 954 posix_acl_release(default_acl); 955 if (acl) 956 posix_acl_release(acl); 957 return 0; 958 } 959
