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 struct posix_acl **acl_by_type(struct inode *inode, int type)
  25 {
  26         switch (type) {
  27         case ACL_TYPE_ACCESS:
  28                 return &inode->i_acl;
  29         case ACL_TYPE_DEFAULT:
  30                 return &inode->i_default_acl;
  31         default:
  32                 BUG();
  33         }
  34 }
  35 EXPORT_SYMBOL(acl_by_type);
  36
  37 struct posix_acl *get_cached_acl(struct inode *inode, int type)
  38 {
  39         struct posix_acl **p = acl_by_type(inode, type);
  40         struct posix_acl *acl = ACCESS_ONCE(*p);
  41         if (acl) {
  42                 spin_lock(&inode->i_lock);
  43                 acl = *p;
  44                 if (acl != ACL_NOT_CACHED)
  45                         acl = posix_acl_dup(acl);
  46                 spin_unlock(&inode->i_lock);
  47         }
  48         return acl;
  49 }
  50 EXPORT_SYMBOL(get_cached_acl);
  51
  52 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
  53 {
  54         return rcu_dereference(*acl_by_type(inode, type));
  55 }
  56 EXPORT_SYMBOL(get_cached_acl_rcu);
  57
  58 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
  59 {
  60         struct posix_acl **p = acl_by_type(inode, type);
  61         struct posix_acl *old;
  62         spin_lock(&inode->i_lock);
  63         old = *p;
  64         rcu_assign_pointer(*p, posix_acl_dup(acl));
  65         spin_unlock(&inode->i_lock);
  66         if (old != ACL_NOT_CACHED)
  67                 posix_acl_release(old);
  68 }
  69 EXPORT_SYMBOL(set_cached_acl);
  70
  71 void forget_cached_acl(struct inode *inode, int type)
  72 {
  73         struct posix_acl **p = acl_by_type(inode, type);
  74         struct posix_acl *old;
  75         spin_lock(&inode->i_lock);
  76         old = *p;
  77         *p = ACL_NOT_CACHED;
  78         spin_unlock(&inode->i_lock);
  79         if (old != ACL_NOT_CACHED)
  80                 posix_acl_release(old);
  81 }
  82 EXPORT_SYMBOL(forget_cached_acl);
  83
  84 void forget_all_cached_acls(struct inode *inode)
  85 {
  86         struct posix_acl *old_access, *old_default;
  87         spin_lock(&inode->i_lock);
  88         old_access = inode->i_acl;
  89         old_default = inode->i_default_acl;
  90         inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
  91         spin_unlock(&inode->i_lock);
  92         if (old_access != ACL_NOT_CACHED)
  93                 posix_acl_release(old_access);
  94         if (old_default != ACL_NOT_CACHED)
  95                 posix_acl_release(old_default);
  96 }
  97 EXPORT_SYMBOL(forget_all_cached_acls);
  98
  99 struct posix_acl *get_acl(struct inode *inode, int type)
 100 {
 101         struct posix_acl *acl;
 102
 103         acl = get_cached_acl(inode, type);
 104         if (acl != ACL_NOT_CACHED)
 105                 return acl;
 106
 107         if (!IS_POSIXACL(inode))
 108                 return NULL;
 109
 110         /*
 111          * A filesystem can force a ACL callback by just never filling the
 112          * ACL cache. But normally you'd fill the cache either at inode
 113          * instantiation time, or on the first ->get_acl call.
 114          *
 115          * If the filesystem doesn't have a get_acl() function at all, we'll
 116          * just create the negative cache entry.
 117          */
 118         if (!inode->i_op->get_acl) {
 119                 set_cached_acl(inode, type, NULL);
 120                 return NULL;
 121         }
 122         return inode->i_op->get_acl(inode, type);
 123 }
 124 EXPORT_SYMBOL(get_acl);
 125
 126 /*
 127  * Init a fresh posix_acl
 128  */
 129 void
 130 posix_acl_init(struct posix_acl *acl, int count)
 131 {
 132         atomic_set(&acl->a_refcount, 1);
 133         acl->a_count = count;
 134 }
 135 EXPORT_SYMBOL(posix_acl_init);
 136
 137 /*
 138  * Allocate a new ACL with the specified number of entries.
 139  */
 140 struct posix_acl *
 141 posix_acl_alloc(int count, gfp_t flags)
 142 {
 143         const size_t size = sizeof(struct posix_acl) +
 144                             count * sizeof(struct posix_acl_entry);
 145         struct posix_acl *acl = kmalloc(size, flags);
 146         if (acl)
 147                 posix_acl_init(acl, count);
 148         return acl;
 149 }
 150 EXPORT_SYMBOL(posix_acl_alloc);
 151
 152 /*
 153  * Clone an ACL.
 154  */
 155 static struct posix_acl *
 156 posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
 157 {
 158         struct posix_acl *clone = NULL;
 159
 160         if (acl) {
 161                 int size = sizeof(struct posix_acl) + acl->a_count *
 162                            sizeof(struct posix_acl_entry);
 163                 clone = kmemdup(acl, size, flags);
 164                 if (clone)
 165                         atomic_set(&clone->a_refcount, 1);
 166         }
 167         return clone;
 168 }
 169
 170 /*
 171  * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
 172  */
 173 int
 174 posix_acl_valid(const struct posix_acl *acl)
 175 {
 176         const struct posix_acl_entry *pa, *pe;
 177         int state = ACL_USER_OBJ;
 178         int needs_mask = 0;
 179
 180         FOREACH_ACL_ENTRY(pa, acl, pe) {
 181                 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
 182                         return -EINVAL;
 183                 switch (pa->e_tag) {
 184                         case ACL_USER_OBJ:
 185                                 if (state == ACL_USER_OBJ) {
 186                                         state = ACL_USER;
 187                                         break;
 188                                 }
 189                                 return -EINVAL;
 190
 191                         case ACL_USER:
 192                                 if (state != ACL_USER)
 193                                         return -EINVAL;
 194                                 if (!uid_valid(pa->e_uid))
 195                                         return -EINVAL;
 196                                 needs_mask = 1;
 197                                 break;
 198
 199                         case ACL_GROUP_OBJ:
 200                                 if (state == ACL_USER) {
 201                                         state = ACL_GROUP;
 202                                         break;
 203                                 }
 204                                 return -EINVAL;
 205
 206                         case ACL_GROUP:
 207                                 if (state != ACL_GROUP)
 208                                         return -EINVAL;
 209                                 if (!gid_valid(pa->e_gid))
 210                                         return -EINVAL;
 211                                 needs_mask = 1;
 212                                 break;
 213
 214                         case ACL_MASK:
 215                                 if (state != ACL_GROUP)
 216                                         return -EINVAL;
 217                                 state = ACL_OTHER;
 218                                 break;
 219
 220                         case ACL_OTHER:
 221                                 if (state == ACL_OTHER ||
 222                                     (state == ACL_GROUP && !needs_mask)) {
 223                                         state = 0;
 224                                         break;
 225                                 }
 226                                 return -EINVAL;
 227
 228                         default:
 229                                 return -EINVAL;
 230                 }
 231         }
 232         if (state == 0)
 233                 return 0;
 234         return -EINVAL;
 235 }
 236 EXPORT_SYMBOL(posix_acl_valid);
 237
 238 /*
 239  * Returns 0 if the acl can be exactly represented in the traditional
 240  * file mode permission bits, or else 1. Returns -E... on error.
 241  */
 242 int
 243 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
 244 {
 245         const struct posix_acl_entry *pa, *pe;
 246         umode_t mode = 0;
 247         int not_equiv = 0;
 248
 249         FOREACH_ACL_ENTRY(pa, acl, pe) {
 250                 switch (pa->e_tag) {
 251                         case ACL_USER_OBJ:
 252                                 mode |= (pa->e_perm & S_IRWXO) << 6;
 253                                 break;
 254                         case ACL_GROUP_OBJ:
 255                                 mode |= (pa->e_perm & S_IRWXO) << 3;
 256                                 break;
 257                         case ACL_OTHER:
 258                                 mode |= pa->e_perm & S_IRWXO;
 259                                 break;
 260                         case ACL_MASK:
 261                                 mode = (mode & ~S_IRWXG) |
 262                                        ((pa->e_perm & S_IRWXO) << 3);
 263                                 not_equiv = 1;
 264                                 break;
 265                         case ACL_USER:
 266                         case ACL_GROUP:
 267                                 not_equiv = 1;
 268                                 break;
 269                         default:
 270                                 return -EINVAL;
 271                 }
 272         }
 273         if (mode_p)
 274                 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 275         return not_equiv;
 276 }
 277 EXPORT_SYMBOL(posix_acl_equiv_mode);
 278
 279 /*
 280  * Create an ACL representing the file mode permission bits of an inode.
 281  */
 282 struct posix_acl *
 283 posix_acl_from_mode(umode_t mode, gfp_t flags)
 284 {
 285         struct posix_acl *acl = posix_acl_alloc(3, flags);
 286         if (!acl)
 287                 return ERR_PTR(-ENOMEM);
 288
 289         acl->a_entries[0].e_tag  = ACL_USER_OBJ;
 290         acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
 291
 292         acl->a_entries[1].e_tag  = ACL_GROUP_OBJ;
 293         acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
 294
 295         acl->a_entries[2].e_tag  = ACL_OTHER;
 296         acl->a_entries[2].e_perm = (mode & S_IRWXO);
 297         return acl;
 298 }
 299 EXPORT_SYMBOL(posix_acl_from_mode);
 300
 301 /*
 302  * Return 0 if current is granted want access to the inode
 303  * by the acl. Returns -E... otherwise.
 304  */
 305 int
 306 posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
 307 {
 308         const struct posix_acl_entry *pa, *pe, *mask_obj;
 309         int found = 0;
 310
 311         want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
 312
 313         FOREACH_ACL_ENTRY(pa, acl, pe) {
 314                 switch(pa->e_tag) {
 315                         case ACL_USER_OBJ:
 316                                 /* (May have been checked already) */
 317                                 if (uid_eq(inode->i_uid, current_fsuid()))
 318                                         goto check_perm;
 319                                 break;
 320                         case ACL_USER:
 321                                 if (uid_eq(pa->e_uid, current_fsuid()))
 322                                         goto mask;
 323                                 break;
 324                         case ACL_GROUP_OBJ:
 325                                 if (in_group_p(inode->i_gid)) {
 326                                         found = 1;
 327                                         if ((pa->e_perm & want) == want)
 328                                                 goto mask;
 329                                 }
 330                                 break;
 331                         case ACL_GROUP:
 332                                 if (in_group_p(pa->e_gid)) {
 333                                         found = 1;
 334                                         if ((pa->e_perm & want) == want)
 335                                                 goto mask;
 336                                 }
 337                                 break;
 338                         case ACL_MASK:
 339                                 break;
 340                         case ACL_OTHER:
 341                                 if (found)
 342                                         return -EACCES;
 343                                 else
 344                                         goto check_perm;
 345                         default:
 346                                 return -EIO;
 347                 }
 348         }
 349         return -EIO;
 350
 351 mask:
 352         for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
 353                 if (mask_obj->e_tag == ACL_MASK) {
 354                         if ((pa->e_perm & mask_obj->e_perm & want) == want)
 355                                 return 0;
 356                         return -EACCES;
 357                 }
 358         }
 359
 360 check_perm:
 361         if ((pa->e_perm & want) == want)
 362                 return 0;
 363         return -EACCES;
 364 }
 365
 366 /*
 367  * Modify acl when creating a new inode. The caller must ensure the acl is
 368  * only referenced once.
 369  *
 370  * mode_p initially must contain the mode parameter to the open() / creat()
 371  * system calls. All permissions that are not granted by the acl are removed.
 372  * The permissions in the acl are changed to reflect the mode_p parameter.
 373  */
 374 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
 375 {
 376         struct posix_acl_entry *pa, *pe;
 377         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 378         umode_t mode = *mode_p;
 379         int not_equiv = 0;
 380
 381         /* assert(atomic_read(acl->a_refcount) == 1); */
 382
 383         FOREACH_ACL_ENTRY(pa, acl, pe) {
 384                 switch(pa->e_tag) {
 385                         case ACL_USER_OBJ:
 386                                 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
 387                                 mode &= (pa->e_perm << 6) | ~S_IRWXU;
 388                                 break;
 389
 390                         case ACL_USER:
 391                         case ACL_GROUP:
 392                                 not_equiv = 1;
 393                                 break;
 394
 395                         case ACL_GROUP_OBJ:
 396                                 group_obj = pa;
 397                                 break;
 398
 399                         case ACL_OTHER:
 400                                 pa->e_perm &= mode | ~S_IRWXO;
 401                                 mode &= pa->e_perm | ~S_IRWXO;
 402                                 break;
 403
 404                         case ACL_MASK:
 405                                 mask_obj = pa;
 406                                 not_equiv = 1;
 407                                 break;
 408
 409                         default:
 410                                 return -EIO;
 411                 }
 412         }
 413
 414         if (mask_obj) {
 415                 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 416                 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
 417         } else {
 418                 if (!group_obj)
 419                         return -EIO;
 420                 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 421                 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
 422         }
 423
 424         *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 425         return not_equiv;
 426 }
 427
 428 /*
 429  * Modify the ACL for the chmod syscall.
 430  */
 431 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
 432 {
 433         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 434         struct posix_acl_entry *pa, *pe;
 435
 436         /* assert(atomic_read(acl->a_refcount) == 1); */
 437
 438         FOREACH_ACL_ENTRY(pa, acl, pe) {
 439                 switch(pa->e_tag) {
 440                         case ACL_USER_OBJ:
 441                                 pa->e_perm = (mode & S_IRWXU) >> 6;
 442                                 break;
 443
 444                         case ACL_USER:
 445                         case ACL_GROUP:
 446                                 break;
 447
 448                         case ACL_GROUP_OBJ:
 449                                 group_obj = pa;
 450                                 break;
 451
 452                         case ACL_MASK:
 453                                 mask_obj = pa;
 454                                 break;
 455
 456                         case ACL_OTHER:
 457                                 pa->e_perm = (mode & S_IRWXO);
 458                                 break;
 459
 460                         default:
 461                                 return -EIO;
 462                 }
 463         }
 464
 465         if (mask_obj) {
 466                 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
 467         } else {
 468                 if (!group_obj)
 469                         return -EIO;
 470                 group_obj->e_perm = (mode & S_IRWXG) >> 3;
 471         }
 472
 473         return 0;
 474 }
 475
 476 int
 477 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
 478 {
 479         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 480         int err = -ENOMEM;
 481         if (clone) {
 482                 err = posix_acl_create_masq(clone, mode_p);
 483                 if (err < 0) {
 484                         posix_acl_release(clone);
 485                         clone = NULL;
 486                 }
 487         }
 488         posix_acl_release(*acl);
 489         *acl = clone;
 490         return err;
 491 }
 492 EXPORT_SYMBOL(__posix_acl_create);
 493
 494 int
 495 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
 496 {
 497         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 498         int err = -ENOMEM;
 499         if (clone) {
 500                 err = __posix_acl_chmod_masq(clone, mode);
 501                 if (err) {
 502                         posix_acl_release(clone);
 503                         clone = NULL;
 504                 }
 505         }
 506         posix_acl_release(*acl);
 507         *acl = clone;
 508         return err;
 509 }
 510 EXPORT_SYMBOL(__posix_acl_chmod);
 511
 512 int
 513 posix_acl_chmod(struct inode *inode, umode_t mode)
 514 {
 515         struct posix_acl *acl;
 516         int ret = 0;
 517
 518         if (!IS_POSIXACL(inode))
 519                 return 0;
 520         if (!inode->i_op->set_acl)
 521                 return -EOPNOTSUPP;
 522
 523         acl = get_acl(inode, ACL_TYPE_ACCESS);
 524         if (IS_ERR_OR_NULL(acl))
 525                 return PTR_ERR(acl);
 526
 527         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 528         if (ret)
 529                 return ret;
 530         ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
 531         posix_acl_release(acl);
 532         return ret;
 533 }
 534 EXPORT_SYMBOL(posix_acl_chmod);
 535
 536 int
 537 posix_acl_create(struct inode *dir, umode_t *mode,
 538                 struct posix_acl **default_acl, struct posix_acl **acl)
 539 {
 540         struct posix_acl *p;
 541         int ret;
 542
 543         if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
 544                 goto no_acl;
 545
 546         p = get_acl(dir, ACL_TYPE_DEFAULT);
 547         if (IS_ERR(p))
 548                 return PTR_ERR(p);
 549
 550         if (!p) {
 551                 *mode &= ~current_umask();
 552                 goto no_acl;
 553         }
 554
 555         *acl = posix_acl_clone(p, GFP_NOFS);
 556         if (!*acl)
 557                 return -ENOMEM;
 558
 559         ret = posix_acl_create_masq(*acl, mode);
 560         if (ret < 0) {
 561                 posix_acl_release(*acl);
 562                 return -ENOMEM;
 563         }
 564
 565         if (ret == 0) {
 566                 posix_acl_release(*acl);
 567                 *acl = NULL;
 568         }
 569
 570         if (!S_ISDIR(*mode)) {
 571                 posix_acl_release(p);
 572                 *default_acl = NULL;
 573         } else {
 574                 *default_acl = p;
 575         }
 576         return 0;
 577
 578 no_acl:
 579         *default_acl = NULL;
 580         *acl = NULL;
 581         return 0;
 582 }
 583 EXPORT_SYMBOL_GPL(posix_acl_create);
 584
 585 /*
 586  * Fix up the uids and gids in posix acl extended attributes in place.
 587  */
 588 static void posix_acl_fix_xattr_userns(
 589         struct user_namespace *to, struct user_namespace *from,
 590         void *value, size_t size)
 591 {
 592         posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
 593         posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
 594         int count;
 595         kuid_t uid;
 596         kgid_t gid;
 597
 598         if (!value)
 599                 return;
 600         if (size < sizeof(posix_acl_xattr_header))
 601                 return;
 602         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 603                 return;
 604
 605         count = posix_acl_xattr_count(size);
 606         if (count < 0)
 607                 return;
 608         if (count == 0)
 609                 return;
 610
 611         for (end = entry + count; entry != end; entry++) {
 612                 switch(le16_to_cpu(entry->e_tag)) {
 613                 case ACL_USER:
 614                         uid = make_kuid(from, le32_to_cpu(entry->e_id));
 615                         entry->e_id = cpu_to_le32(from_kuid(to, uid));
 616                         break;
 617                 case ACL_GROUP:
 618                         gid = make_kgid(from, le32_to_cpu(entry->e_id));
 619                         entry->e_id = cpu_to_le32(from_kgid(to, gid));
 620                         break;
 621                 default:
 622                         break;
 623                 }
 624         }
 625 }
 626
 627 void posix_acl_fix_xattr_from_user(void *value, size_t size)
 628 {
 629         struct user_namespace *user_ns = current_user_ns();
 630         if (user_ns == &init_user_ns)
 631                 return;
 632         posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
 633 }
 634
 635 void posix_acl_fix_xattr_to_user(void *value, size_t size)
 636 {
 637         struct user_namespace *user_ns = current_user_ns();
 638         if (user_ns == &init_user_ns)
 639                 return;
 640         posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
 641 }
 642
 643 /*
 644  * Convert from extended attribute to in-memory representation.
 645  */
 646 struct posix_acl *
 647 posix_acl_from_xattr(struct user_namespace *user_ns,
 648                      const void *value, size_t size)
 649 {
 650         posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
 651         posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
 652         int count;
 653         struct posix_acl *acl;
 654         struct posix_acl_entry *acl_e;
 655
 656         if (!value)
 657                 return NULL;
 658         if (size < sizeof(posix_acl_xattr_header))
 659                  return ERR_PTR(-EINVAL);
 660         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 661                 return ERR_PTR(-EOPNOTSUPP);
 662
 663         count = posix_acl_xattr_count(size);
 664         if (count < 0)
 665                 return ERR_PTR(-EINVAL);
 666         if (count == 0)
 667                 return NULL;
 668
 669         acl = posix_acl_alloc(count, GFP_NOFS);
 670         if (!acl)
 671                 return ERR_PTR(-ENOMEM);
 672         acl_e = acl->a_entries;
 673
 674         for (end = entry + count; entry != end; acl_e++, entry++) {
 675                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
 676                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
 677
 678                 switch(acl_e->e_tag) {
 679                         case ACL_USER_OBJ:
 680                         case ACL_GROUP_OBJ:
 681                         case ACL_MASK:
 682                         case ACL_OTHER:
 683                                 break;
 684
 685                         case ACL_USER:
 686                                 acl_e->e_uid =
 687                                         make_kuid(user_ns,
 688                                                   le32_to_cpu(entry->e_id));
 689                                 if (!uid_valid(acl_e->e_uid))
 690                                         goto fail;
 691                                 break;
 692                         case ACL_GROUP:
 693                                 acl_e->e_gid =
 694                                         make_kgid(user_ns,
 695                                                   le32_to_cpu(entry->e_id));
 696                                 if (!gid_valid(acl_e->e_gid))
 697                                         goto fail;
 698                                 break;
 699
 700                         default:
 701                                 goto fail;
 702                 }
 703         }
 704         return acl;
 705
 706 fail:
 707         posix_acl_release(acl);
 708         return ERR_PTR(-EINVAL);
 709 }
 710 EXPORT_SYMBOL (posix_acl_from_xattr);
 711
 712 /*
 713  * Convert from in-memory to extended attribute representation.
 714  */
 715 int
 716 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
 717                    void *buffer, size_t size)
 718 {
 719         posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
 720         posix_acl_xattr_entry *ext_entry = ext_acl->a_entries;
 721         int real_size, n;
 722
 723         real_size = posix_acl_xattr_size(acl->a_count);
 724         if (!buffer)
 725                 return real_size;
 726         if (real_size > size)
 727                 return -ERANGE;
 728
 729         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
 730
 731         for (n=0; n < acl->a_count; n++, ext_entry++) {
 732                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 733                 ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 734                 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
 735                 switch(acl_e->e_tag) {
 736                 case ACL_USER:
 737                         ext_entry->e_id =
 738                                 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
 739                         break;
 740                 case ACL_GROUP:
 741                         ext_entry->e_id =
 742                                 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
 743                         break;
 744                 default:
 745                         ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
 746                         break;
 747                 }
 748         }
 749         return real_size;
 750 }
 751 EXPORT_SYMBOL (posix_acl_to_xattr);
 752
 753 static int
 754 posix_acl_xattr_get(struct dentry *dentry, const char *name,
 755                 void *value, size_t size, int type)
 756 {
 757         struct posix_acl *acl;
 758         int error;
 759
 760         if (!IS_POSIXACL(dentry->d_inode))
 761                 return -EOPNOTSUPP;
 762         if (S_ISLNK(dentry->d_inode->i_mode))
 763                 return -EOPNOTSUPP;
 764
 765         acl = get_acl(dentry->d_inode, type);
 766         if (IS_ERR(acl))
 767                 return PTR_ERR(acl);
 768         if (acl == NULL)
 769                 return -ENODATA;
 770
 771         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 772         posix_acl_release(acl);
 773
 774         return error;
 775 }
 776
 777 static int
 778 posix_acl_xattr_set(struct dentry *dentry, const char *name,
 779                 const void *value, size_t size, int flags, int type)
 780 {
 781         struct inode *inode = dentry->d_inode;
 782         struct posix_acl *acl = NULL;
 783         int ret;
 784
 785         if (!IS_POSIXACL(inode))
 786                 return -EOPNOTSUPP;
 787         if (!inode->i_op->set_acl)
 788                 return -EOPNOTSUPP;
 789
 790         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 791                 return value ? -EACCES : 0;
 792         if (!inode_owner_or_capable(inode))
 793                 return -EPERM;
 794
 795         if (value) {
 796                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 797                 if (IS_ERR(acl))
 798                         return PTR_ERR(acl);
 799
 800                 if (acl) {
 801                         ret = posix_acl_valid(acl);
 802                         if (ret)
 803                                 goto out;
 804                 }
 805         }
 806
 807         ret = inode->i_op->set_acl(inode, acl, type);
 808 out:
 809         posix_acl_release(acl);
 810         return ret;
 811 }
 812
 813 static size_t
 814 posix_acl_xattr_list(struct dentry *dentry, char *list, size_t list_size,
 815                 const char *name, size_t name_len, int type)
 816 {
 817         const char *xname;
 818         size_t size;
 819
 820         if (!IS_POSIXACL(dentry->d_inode))
 821                 return -EOPNOTSUPP;
 822         if (S_ISLNK(dentry->d_inode->i_mode))
 823                 return -EOPNOTSUPP;
 824
 825         if (type == ACL_TYPE_ACCESS)
 826                 xname = POSIX_ACL_XATTR_ACCESS;
 827         else
 828                 xname = POSIX_ACL_XATTR_DEFAULT;
 829
 830         size = strlen(xname) + 1;
 831         if (list && size <= list_size)
 832                 memcpy(list, xname, size);
 833         return size;
 834 }
 835
 836 const struct xattr_handler posix_acl_access_xattr_handler = {
 837         .prefix = POSIX_ACL_XATTR_ACCESS,
 838         .flags = ACL_TYPE_ACCESS,
 839         .list = posix_acl_xattr_list,
 840         .get = posix_acl_xattr_get,
 841         .set = posix_acl_xattr_set,
 842 };
 843 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
 844
 845 const struct xattr_handler posix_acl_default_xattr_handler = {
 846         .prefix = POSIX_ACL_XATTR_DEFAULT,
 847         .flags = ACL_TYPE_DEFAULT,
 848         .list = posix_acl_xattr_list,
 849         .get = posix_acl_xattr_get,
 850         .set = posix_acl_xattr_set,
 851 };
 852 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
 853
 854 int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 855 {
 856         int error;
 857
 858         if (type == ACL_TYPE_ACCESS) {
 859                 error = posix_acl_equiv_mode(acl, &inode->i_mode);
 860                 if (error < 0)
 861                         return 0;
 862                 if (error == 0)
 863                         acl = NULL;
 864         }
 865
 866         inode->i_ctime = CURRENT_TIME;
 867         set_cached_acl(inode, type, acl);
 868         return 0;
 869 }
 870
 871 int simple_acl_create(struct inode *dir, struct inode *inode)
 872 {
 873         struct posix_acl *default_acl, *acl;
 874         int error;
 875
 876         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 877         if (error)
 878                 return error;
 879
 880         set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
 881         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 882
 883         if (default_acl)
 884                 posix_acl_release(default_acl);
 885         if (acl)
 886                 posix_acl_release(acl);
 887         return 0;
 888 }