fs/posix_acl.c

   1 /*
   2  * Copyright (C) 2002,2003 by Andreas Gruenbacher <[email protected]>
   3  *
   4  * Fixes from William Schumacher incorporated on 15 March 2001.
   5  *    (Reported by Charles Bertsch, <[email protected]>).
   6  */
   7
   8 /*
   9  *  This file contains generic functions for manipulating
  10  *  POSIX 1003.1e draft standard 17 ACLs.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/slab.h>
  15 #include <linux/atomic.h>
  16 #include <linux/fs.h>
  17 #include <linux/sched.h>
  18 #include <linux/posix_acl.h>
  19 #include <linux/posix_acl_xattr.h>
  20 #include <linux/xattr.h>
  21 #include <linux/export.h>
  22 #include <linux/user_namespace.h>
  23
  24 EXPORT_SYMBOL(posix_acl_init);
  25 EXPORT_SYMBOL(posix_acl_alloc);
  26 EXPORT_SYMBOL(posix_acl_valid);
  27 EXPORT_SYMBOL(posix_acl_equiv_mode);
  28 EXPORT_SYMBOL(posix_acl_from_mode);
  29
  30 struct posix_acl *get_acl(struct inode *inode, int type)
  31 {
  32         struct posix_acl *acl;
  33
  34         acl = get_cached_acl(inode, type);
  35         if (acl != ACL_NOT_CACHED)
  36                 return acl;
  37
  38         if (!IS_POSIXACL(inode))
  39                 return NULL;
  40
  41         /*
  42          * A filesystem can force a ACL callback by just never filling the
  43          * ACL cache. But normally you'd fill the cache either at inode
  44          * instantiation time, or on the first ->get_acl call.
  45          *
  46          * If the filesystem doesn't have a get_acl() function at all, we'll
  47          * just create the negative cache entry.
  48          */
  49         if (!inode->i_op->get_acl) {
  50                 set_cached_acl(inode, type, NULL);
  51                 return NULL;
  52         }
  53         return inode->i_op->get_acl(inode, type);
  54 }
  55 EXPORT_SYMBOL(get_acl);
  56
  57 /*
  58  * Init a fresh posix_acl
  59  */
  60 void
  61 posix_acl_init(struct posix_acl *acl, int count)
  62 {
  63         atomic_set(&acl->a_refcount, 1);
  64         acl->a_count = count;
  65 }
  66
  67 /*
  68  * Allocate a new ACL with the specified number of entries.
  69  */
  70 struct posix_acl *
  71 posix_acl_alloc(int count, gfp_t flags)
  72 {
  73         const size_t size = sizeof(struct posix_acl) +
  74                             count * sizeof(struct posix_acl_entry);
  75         struct posix_acl *acl = kmalloc(size, flags);
  76         if (acl)
  77                 posix_acl_init(acl, count);
  78         return acl;
  79 }
  80
  81 /*
  82  * Clone an ACL.
  83  */
  84 static struct posix_acl *
  85 posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
  86 {
  87         struct posix_acl *clone = NULL;
  88
  89         if (acl) {
  90                 int size = sizeof(struct posix_acl) + acl->a_count *
  91                            sizeof(struct posix_acl_entry);
  92                 clone = kmemdup(acl, size, flags);
  93                 if (clone)
  94                         atomic_set(&clone->a_refcount, 1);
  95         }
  96         return clone;
  97 }
  98
  99 /*
 100  * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
 101  */
 102 int
 103 posix_acl_valid(const struct posix_acl *acl)
 104 {
 105         const struct posix_acl_entry *pa, *pe;
 106         int state = ACL_USER_OBJ;
 107         kuid_t prev_uid = INVALID_UID;
 108         kgid_t prev_gid = INVALID_GID;
 109         int needs_mask = 0;
 110
 111         FOREACH_ACL_ENTRY(pa, acl, pe) {
 112                 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
 113                         return -EINVAL;
 114                 switch (pa->e_tag) {
 115                         case ACL_USER_OBJ:
 116                                 if (state == ACL_USER_OBJ) {
 117                                         state = ACL_USER;
 118                                         break;
 119                                 }
 120                                 return -EINVAL;
 121
 122                         case ACL_USER:
 123                                 if (state != ACL_USER)
 124                                         return -EINVAL;
 125                                 if (!uid_valid(pa->e_uid))
 126                                         return -EINVAL;
 127                                 if (uid_valid(prev_uid) &&
 128                                     uid_lte(pa->e_uid, prev_uid))
 129                                         return -EINVAL;
 130                                 prev_uid = pa->e_uid;
 131                                 needs_mask = 1;
 132                                 break;
 133
 134                         case ACL_GROUP_OBJ:
 135                                 if (state == ACL_USER) {
 136                                         state = ACL_GROUP;
 137                                         break;
 138                                 }
 139                                 return -EINVAL;
 140
 141                         case ACL_GROUP:
 142                                 if (state != ACL_GROUP)
 143                                         return -EINVAL;
 144                                 if (!gid_valid(pa->e_gid))
 145                                         return -EINVAL;
 146                                 if (gid_valid(prev_gid) &&
 147                                     gid_lte(pa->e_gid, prev_gid))
 148                                         return -EINVAL;
 149                                 prev_gid = pa->e_gid;
 150                                 needs_mask = 1;
 151                                 break;
 152
 153                         case ACL_MASK:
 154                                 if (state != ACL_GROUP)
 155                                         return -EINVAL;
 156                                 state = ACL_OTHER;
 157                                 break;
 158
 159                         case ACL_OTHER:
 160                                 if (state == ACL_OTHER ||
 161                                     (state == ACL_GROUP && !needs_mask)) {
 162                                         state = 0;
 163                                         break;
 164                                 }
 165                                 return -EINVAL;
 166
 167                         default:
 168                                 return -EINVAL;
 169                 }
 170         }
 171         if (state == 0)
 172                 return 0;
 173         return -EINVAL;
 174 }
 175
 176 /*
 177  * Returns 0 if the acl can be exactly represented in the traditional
 178  * file mode permission bits, or else 1. Returns -E... on error.
 179  */
 180 int
 181 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
 182 {
 183         const struct posix_acl_entry *pa, *pe;
 184         umode_t mode = 0;
 185         int not_equiv = 0;
 186
 187         FOREACH_ACL_ENTRY(pa, acl, pe) {
 188                 switch (pa->e_tag) {
 189                         case ACL_USER_OBJ:
 190                                 mode |= (pa->e_perm & S_IRWXO) << 6;
 191                                 break;
 192                         case ACL_GROUP_OBJ:
 193                                 mode |= (pa->e_perm & S_IRWXO) << 3;
 194                                 break;
 195                         case ACL_OTHER:
 196                                 mode |= pa->e_perm & S_IRWXO;
 197                                 break;
 198                         case ACL_MASK:
 199                                 mode = (mode & ~S_IRWXG) |
 200                                        ((pa->e_perm & S_IRWXO) << 3);
 201                                 not_equiv = 1;
 202                                 break;
 203                         case ACL_USER:
 204                         case ACL_GROUP:
 205                                 not_equiv = 1;
 206                                 break;
 207                         default:
 208                                 return -EINVAL;
 209                 }
 210         }
 211         if (mode_p)
 212                 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 213         return not_equiv;
 214 }
 215
 216 /*
 217  * Create an ACL representing the file mode permission bits of an inode.
 218  */
 219 struct posix_acl *
 220 posix_acl_from_mode(umode_t mode, gfp_t flags)
 221 {
 222         struct posix_acl *acl = posix_acl_alloc(3, flags);
 223         if (!acl)
 224                 return ERR_PTR(-ENOMEM);
 225
 226         acl->a_entries[0].e_tag  = ACL_USER_OBJ;
 227         acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
 228
 229         acl->a_entries[1].e_tag  = ACL_GROUP_OBJ;
 230         acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
 231
 232         acl->a_entries[2].e_tag  = ACL_OTHER;
 233         acl->a_entries[2].e_perm = (mode & S_IRWXO);
 234         return acl;
 235 }
 236
 237 /*
 238  * Return 0 if current is granted want access to the inode
 239  * by the acl. Returns -E... otherwise.
 240  */
 241 int
 242 posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
 243 {
 244         const struct posix_acl_entry *pa, *pe, *mask_obj;
 245         int found = 0;
 246
 247         want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
 248
 249         FOREACH_ACL_ENTRY(pa, acl, pe) {
 250                 switch(pa->e_tag) {
 251                         case ACL_USER_OBJ:
 252                                 /* (May have been checked already) */
 253                                 if (uid_eq(inode->i_uid, current_fsuid()))
 254                                         goto check_perm;
 255                                 break;
 256                         case ACL_USER:
 257                                 if (uid_eq(pa->e_uid, current_fsuid()))
 258                                         goto mask;
 259                                 break;
 260                         case ACL_GROUP_OBJ:
 261                                 if (in_group_p(inode->i_gid)) {
 262                                         found = 1;
 263                                         if ((pa->e_perm & want) == want)
 264                                                 goto mask;
 265                                 }
 266                                 break;
 267                         case ACL_GROUP:
 268                                 if (in_group_p(pa->e_gid)) {
 269                                         found = 1;
 270                                         if ((pa->e_perm & want) == want)
 271                                                 goto mask;
 272                                 }
 273                                 break;
 274                         case ACL_MASK:
 275                                 break;
 276                         case ACL_OTHER:
 277                                 if (found)
 278                                         return -EACCES;
 279                                 else
 280                                         goto check_perm;
 281                         default:
 282                                 return -EIO;
 283                 }
 284         }
 285         return -EIO;
 286
 287 mask:
 288         for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
 289                 if (mask_obj->e_tag == ACL_MASK) {
 290                         if ((pa->e_perm & mask_obj->e_perm & want) == want)
 291                                 return 0;
 292                         return -EACCES;
 293                 }
 294         }
 295
 296 check_perm:
 297         if ((pa->e_perm & want) == want)
 298                 return 0;
 299         return -EACCES;
 300 }
 301
 302 /*
 303  * Modify acl when creating a new inode. The caller must ensure the acl is
 304  * only referenced once.
 305  *
 306  * mode_p initially must contain the mode parameter to the open() / creat()
 307  * system calls. All permissions that are not granted by the acl are removed.
 308  * The permissions in the acl are changed to reflect the mode_p parameter.
 309  */
 310 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
 311 {
 312         struct posix_acl_entry *pa, *pe;
 313         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 314         umode_t mode = *mode_p;
 315         int not_equiv = 0;
 316
 317         /* assert(atomic_read(acl->a_refcount) == 1); */
 318
 319         FOREACH_ACL_ENTRY(pa, acl, pe) {
 320                 switch(pa->e_tag) {
 321                         case ACL_USER_OBJ:
 322                                 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
 323                                 mode &= (pa->e_perm << 6) | ~S_IRWXU;
 324                                 break;
 325
 326                         case ACL_USER:
 327                         case ACL_GROUP:
 328                                 not_equiv = 1;
 329                                 break;
 330
 331                         case ACL_GROUP_OBJ:
 332                                 group_obj = pa;
 333                                 break;
 334
 335                         case ACL_OTHER:
 336                                 pa->e_perm &= mode | ~S_IRWXO;
 337                                 mode &= pa->e_perm | ~S_IRWXO;
 338                                 break;
 339
 340                         case ACL_MASK:
 341                                 mask_obj = pa;
 342                                 not_equiv = 1;
 343                                 break;
 344
 345                         default:
 346                                 return -EIO;
 347                 }
 348         }
 349
 350         if (mask_obj) {
 351                 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 352                 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
 353         } else {
 354                 if (!group_obj)
 355                         return -EIO;
 356                 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 357                 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
 358         }
 359
 360         *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 361         return not_equiv;
 362 }
 363
 364 /*
 365  * Modify the ACL for the chmod syscall.
 366  */
 367 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
 368 {
 369         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 370         struct posix_acl_entry *pa, *pe;
 371
 372         /* assert(atomic_read(acl->a_refcount) == 1); */
 373
 374         FOREACH_ACL_ENTRY(pa, acl, pe) {
 375                 switch(pa->e_tag) {
 376                         case ACL_USER_OBJ:
 377                                 pa->e_perm = (mode & S_IRWXU) >> 6;
 378                                 break;
 379
 380                         case ACL_USER:
 381                         case ACL_GROUP:
 382                                 break;
 383
 384                         case ACL_GROUP_OBJ:
 385                                 group_obj = pa;
 386                                 break;
 387
 388                         case ACL_MASK:
 389                                 mask_obj = pa;
 390                                 break;
 391
 392                         case ACL_OTHER:
 393                                 pa->e_perm = (mode & S_IRWXO);
 394                                 break;
 395
 396                         default:
 397                                 return -EIO;
 398                 }
 399         }
 400
 401         if (mask_obj) {
 402                 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
 403         } else {
 404                 if (!group_obj)
 405                         return -EIO;
 406                 group_obj->e_perm = (mode & S_IRWXG) >> 3;
 407         }
 408
 409         return 0;
 410 }
 411
 412 int
 413 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
 414 {
 415         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 416         int err = -ENOMEM;
 417         if (clone) {
 418                 err = posix_acl_create_masq(clone, mode_p);
 419                 if (err < 0) {
 420                         posix_acl_release(clone);
 421                         clone = NULL;
 422                 }
 423         }
 424         posix_acl_release(*acl);
 425         *acl = clone;
 426         return err;
 427 }
 428 EXPORT_SYMBOL(__posix_acl_create);
 429
 430 int
 431 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
 432 {
 433         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 434         int err = -ENOMEM;
 435         if (clone) {
 436                 err = __posix_acl_chmod_masq(clone, mode);
 437                 if (err) {
 438                         posix_acl_release(clone);
 439                         clone = NULL;
 440                 }
 441         }
 442         posix_acl_release(*acl);
 443         *acl = clone;
 444         return err;
 445 }
 446 EXPORT_SYMBOL(__posix_acl_chmod);
 447
 448 int
 449 posix_acl_chmod(struct inode *inode, umode_t mode)
 450 {
 451         struct posix_acl *acl;
 452         int ret = 0;
 453
 454         if (!IS_POSIXACL(inode))
 455                 return 0;
 456         if (!inode->i_op->set_acl)
 457                 return -EOPNOTSUPP;
 458
 459         acl = get_acl(inode, ACL_TYPE_ACCESS);
 460         if (IS_ERR_OR_NULL(acl))
 461                 return PTR_ERR(acl);
 462
 463         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 464         if (ret)
 465                 return ret;
 466         ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
 467         posix_acl_release(acl);
 468         return ret;
 469 }
 470 EXPORT_SYMBOL(posix_acl_chmod);
 471
 472 int
 473 posix_acl_create(struct inode *dir, umode_t *mode,
 474                 struct posix_acl **default_acl, struct posix_acl **acl)
 475 {
 476         struct posix_acl *p;
 477         int ret;
 478
 479         if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
 480                 goto no_acl;
 481
 482         p = get_acl(dir, ACL_TYPE_DEFAULT);
 483         if (IS_ERR(p))
 484                 return PTR_ERR(p);
 485
 486         if (!p) {
 487                 *mode &= ~current_umask();
 488                 goto no_acl;
 489         }
 490
 491         *acl = posix_acl_clone(p, GFP_NOFS);
 492         if (!*acl)
 493                 return -ENOMEM;
 494
 495         ret = posix_acl_create_masq(*acl, mode);
 496         if (ret < 0) {
 497                 posix_acl_release(*acl);
 498                 return -ENOMEM;
 499         }
 500
 501         if (ret == 0) {
 502                 posix_acl_release(*acl);
 503                 *acl = NULL;
 504         }
 505
 506         if (!S_ISDIR(*mode)) {
 507                 posix_acl_release(p);
 508                 *default_acl = NULL;
 509         } else {
 510                 *default_acl = p;
 511         }
 512         return 0;
 513
 514 no_acl:
 515         *default_acl = NULL;
 516         *acl = NULL;
 517         return 0;
 518 }
 519 EXPORT_SYMBOL_GPL(posix_acl_create);
 520
 521 /*
 522  * Fix up the uids and gids in posix acl extended attributes in place.
 523  */
 524 static void posix_acl_fix_xattr_userns(
 525         struct user_namespace *to, struct user_namespace *from,
 526         void *value, size_t size)
 527 {
 528         posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
 529         posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
 530         int count;
 531         kuid_t uid;
 532         kgid_t gid;
 533
 534         if (!value)
 535                 return;
 536         if (size < sizeof(posix_acl_xattr_header))
 537                 return;
 538         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 539                 return;
 540
 541         count = posix_acl_xattr_count(size);
 542         if (count < 0)
 543                 return;
 544         if (count == 0)
 545                 return;
 546
 547         for (end = entry + count; entry != end; entry++) {
 548                 switch(le16_to_cpu(entry->e_tag)) {
 549                 case ACL_USER:
 550                         uid = make_kuid(from, le32_to_cpu(entry->e_id));
 551                         entry->e_id = cpu_to_le32(from_kuid(to, uid));
 552                         break;
 553                 case ACL_GROUP:
 554                         gid = make_kgid(from, le32_to_cpu(entry->e_id));
 555                         entry->e_id = cpu_to_le32(from_kgid(to, gid));
 556                         break;
 557                 default:
 558                         break;
 559                 }
 560         }
 561 }
 562
 563 void posix_acl_fix_xattr_from_user(void *value, size_t size)
 564 {
 565         struct user_namespace *user_ns = current_user_ns();
 566         if (user_ns == &init_user_ns)
 567                 return;
 568         posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
 569 }
 570
 571 void posix_acl_fix_xattr_to_user(void *value, size_t size)
 572 {
 573         struct user_namespace *user_ns = current_user_ns();
 574         if (user_ns == &init_user_ns)
 575                 return;
 576         posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
 577 }
 578
 579 /*
 580  * Convert from extended attribute to in-memory representation.
 581  */
 582 struct posix_acl *
 583 posix_acl_from_xattr(struct user_namespace *user_ns,
 584                      const void *value, size_t size)
 585 {
 586         posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
 587         posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
 588         int count;
 589         struct posix_acl *acl;
 590         struct posix_acl_entry *acl_e;
 591
 592         if (!value)
 593                 return NULL;
 594         if (size < sizeof(posix_acl_xattr_header))
 595                  return ERR_PTR(-EINVAL);
 596         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 597                 return ERR_PTR(-EOPNOTSUPP);
 598
 599         count = posix_acl_xattr_count(size);
 600         if (count < 0)
 601                 return ERR_PTR(-EINVAL);
 602         if (count == 0)
 603                 return NULL;
 604
 605         acl = posix_acl_alloc(count, GFP_NOFS);
 606         if (!acl)
 607                 return ERR_PTR(-ENOMEM);
 608         acl_e = acl->a_entries;
 609
 610         for (end = entry + count; entry != end; acl_e++, entry++) {
 611                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
 612                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
 613
 614                 switch(acl_e->e_tag) {
 615                         case ACL_USER_OBJ:
 616                         case ACL_GROUP_OBJ:
 617                         case ACL_MASK:
 618                         case ACL_OTHER:
 619                                 break;
 620
 621                         case ACL_USER:
 622                                 acl_e->e_uid =
 623                                         make_kuid(user_ns,
 624                                                   le32_to_cpu(entry->e_id));
 625                                 if (!uid_valid(acl_e->e_uid))
 626                                         goto fail;
 627                                 break;
 628                         case ACL_GROUP:
 629                                 acl_e->e_gid =
 630                                         make_kgid(user_ns,
 631                                                   le32_to_cpu(entry->e_id));
 632                                 if (!gid_valid(acl_e->e_gid))
 633                                         goto fail;
 634                                 break;
 635
 636                         default:
 637                                 goto fail;
 638                 }
 639         }
 640         return acl;
 641
 642 fail:
 643         posix_acl_release(acl);
 644         return ERR_PTR(-EINVAL);
 645 }
 646 EXPORT_SYMBOL (posix_acl_from_xattr);
 647
 648 /*
 649  * Convert from in-memory to extended attribute representation.
 650  */
 651 int
 652 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
 653                    void *buffer, size_t size)
 654 {
 655         posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
 656         posix_acl_xattr_entry *ext_entry = ext_acl->a_entries;
 657         int real_size, n;
 658
 659         real_size = posix_acl_xattr_size(acl->a_count);
 660         if (!buffer)
 661                 return real_size;
 662         if (real_size > size)
 663                 return -ERANGE;
 664
 665         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
 666
 667         for (n=0; n < acl->a_count; n++, ext_entry++) {
 668                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 669                 ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 670                 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
 671                 switch(acl_e->e_tag) {
 672                 case ACL_USER:
 673                         ext_entry->e_id =
 674                                 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
 675                         break;
 676                 case ACL_GROUP:
 677                         ext_entry->e_id =
 678                                 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
 679                         break;
 680                 default:
 681                         ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
 682                         break;
 683                 }
 684         }
 685         return real_size;
 686 }
 687 EXPORT_SYMBOL (posix_acl_to_xattr);
 688
 689 static int
 690 posix_acl_xattr_get(struct dentry *dentry, const char *name,
 691                 void *value, size_t size, int type)
 692 {
 693         struct posix_acl *acl;
 694         int error;
 695
 696         if (!IS_POSIXACL(dentry->d_inode))
 697                 return -EOPNOTSUPP;
 698         if (S_ISLNK(dentry->d_inode->i_mode))
 699                 return -EOPNOTSUPP;
 700
 701         acl = get_acl(dentry->d_inode, type);
 702         if (IS_ERR(acl))
 703                 return PTR_ERR(acl);
 704         if (acl == NULL)
 705                 return -ENODATA;
 706
 707         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 708         posix_acl_release(acl);
 709
 710         return error;
 711 }
 712
 713 static int
 714 posix_acl_xattr_set(struct dentry *dentry, const char *name,
 715                 const void *value, size_t size, int flags, int type)
 716 {
 717         struct inode *inode = dentry->d_inode;
 718         struct posix_acl *acl = NULL;
 719         int ret;
 720
 721         if (!IS_POSIXACL(inode))
 722                 return -EOPNOTSUPP;
 723         if (!inode->i_op->set_acl)
 724                 return -EOPNOTSUPP;
 725
 726         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 727                 return value ? -EACCES : 0;
 728         if (!inode_owner_or_capable(inode))
 729                 return -EPERM;
 730
 731         if (value) {
 732                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 733                 if (IS_ERR(acl))
 734                         return PTR_ERR(acl);
 735
 736                 if (acl) {
 737                         ret = posix_acl_valid(acl);
 738                         if (ret)
 739                                 goto out;
 740                 }
 741         }
 742
 743         ret = inode->i_op->set_acl(inode, acl, type);
 744 out:
 745         posix_acl_release(acl);
 746         return ret;
 747 }
 748
 749 static size_t
 750 posix_acl_xattr_list(struct dentry *dentry, char *list, size_t list_size,
 751                 const char *name, size_t name_len, int type)
 752 {
 753         const char *xname;
 754         size_t size;
 755
 756         if (!IS_POSIXACL(dentry->d_inode))
 757                 return -EOPNOTSUPP;
 758         if (S_ISLNK(dentry->d_inode->i_mode))
 759                 return -EOPNOTSUPP;
 760
 761         if (type == ACL_TYPE_ACCESS)
 762                 xname = POSIX_ACL_XATTR_ACCESS;
 763         else
 764                 xname = POSIX_ACL_XATTR_DEFAULT;
 765
 766         size = strlen(xname) + 1;
 767         if (list && size <= list_size)
 768                 memcpy(list, xname, size);
 769         return size;
 770 }
 771
 772 const struct xattr_handler posix_acl_access_xattr_handler = {
 773         .prefix = POSIX_ACL_XATTR_ACCESS,
 774         .flags = ACL_TYPE_ACCESS,
 775         .list = posix_acl_xattr_list,
 776         .get = posix_acl_xattr_get,
 777         .set = posix_acl_xattr_set,
 778 };
 779 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
 780
 781 const struct xattr_handler posix_acl_default_xattr_handler = {
 782         .prefix = POSIX_ACL_XATTR_DEFAULT,
 783         .flags = ACL_TYPE_DEFAULT,
 784         .list = posix_acl_xattr_list,
 785         .get = posix_acl_xattr_get,
 786         .set = posix_acl_xattr_set,
 787 };
 788 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
 789
 790 int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 791 {
 792         int error;
 793
 794         if (type == ACL_TYPE_ACCESS) {
 795                 error = posix_acl_equiv_mode(acl, &inode->i_mode);
 796                 if (error < 0)
 797                         return 0;
 798                 if (error == 0)
 799                         acl = NULL;
 800         }
 801
 802         inode->i_ctime = CURRENT_TIME;
 803         set_cached_acl(inode, type, acl);
 804         return 0;
 805 }
 806
 807 int simple_acl_create(struct inode *dir, struct inode *inode)
 808 {
 809         struct posix_acl *default_acl, *acl;
 810         int error;
 811
 812         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 813         if (error)
 814                 return error;
 815
 816         set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
 817         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 818
 819         if (default_acl)
 820                 posix_acl_release(default_acl);
 821         if (acl)
 822                 posix_acl_release(acl);
 823         return 0;
 824 }