fs/posix_acl.c

   1 /*
   2  * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org>
   3  *
   4  * Fixes from William Schumacher incorporated on 15 March 2001.
   5  *    (Reported by Charles Bertsch, <CBertsch@microtest.com>).
   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                 if (acl == ERR_PTR(-EOPNOTSUPP))
 526                         return 0;
 527                 return PTR_ERR(acl);
 528         }
 529
 530         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 531         if (ret)
 532                 return ret;
 533         ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
 534         posix_acl_release(acl);
 535         return ret;
 536 }
 537 EXPORT_SYMBOL(posix_acl_chmod);
 538
 539 int
 540 posix_acl_create(struct inode *dir, umode_t *mode,
 541                 struct posix_acl **default_acl, struct posix_acl **acl)
 542 {
 543         struct posix_acl *p;
 544         int ret;
 545
 546         if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
 547                 goto no_acl;
 548
 549         p = get_acl(dir, ACL_TYPE_DEFAULT);
 550         if (IS_ERR(p)) {
 551                 if (p == ERR_PTR(-EOPNOTSUPP))
 552                         goto apply_umask;
 553                 return PTR_ERR(p);
 554         }
 555
 556         if (!p)
 557                 goto apply_umask;
 558
 559         *acl = posix_acl_clone(p, GFP_NOFS);
 560         if (!*acl)
 561                 return -ENOMEM;
 562
 563         ret = posix_acl_create_masq(*acl, mode);
 564         if (ret < 0) {
 565                 posix_acl_release(*acl);
 566                 return -ENOMEM;
 567         }
 568
 569         if (ret == 0) {
 570                 posix_acl_release(*acl);
 571                 *acl = NULL;
 572         }
 573
 574         if (!S_ISDIR(*mode)) {
 575                 posix_acl_release(p);
 576                 *default_acl = NULL;
 577         } else {
 578                 *default_acl = p;
 579         }
 580         return 0;
 581
 582 apply_umask:
 583         *mode &= ~current_umask();
 584 no_acl:
 585         *default_acl = NULL;
 586         *acl = NULL;
 587         return 0;
 588 }
 589 EXPORT_SYMBOL_GPL(posix_acl_create);
 590
 591 /*
 592  * Fix up the uids and gids in posix acl extended attributes in place.
 593  */
 594 static void posix_acl_fix_xattr_userns(
 595         struct user_namespace *to, struct user_namespace *from,
 596         void *value, size_t size)
 597 {
 598         posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
 599         posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
 600         int count;
 601         kuid_t uid;
 602         kgid_t gid;
 603
 604         if (!value)
 605                 return;
 606         if (size < sizeof(posix_acl_xattr_header))
 607                 return;
 608         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 609                 return;
 610
 611         count = posix_acl_xattr_count(size);
 612         if (count < 0)
 613                 return;
 614         if (count == 0)
 615                 return;
 616
 617         for (end = entry + count; entry != end; entry++) {
 618                 switch(le16_to_cpu(entry->e_tag)) {
 619                 case ACL_USER:
 620                         uid = make_kuid(from, le32_to_cpu(entry->e_id));
 621                         entry->e_id = cpu_to_le32(from_kuid(to, uid));
 622                         break;
 623                 case ACL_GROUP:
 624                         gid = make_kgid(from, le32_to_cpu(entry->e_id));
 625                         entry->e_id = cpu_to_le32(from_kgid(to, gid));
 626                         break;
 627                 default:
 628                         break;
 629                 }
 630         }
 631 }
 632
 633 void posix_acl_fix_xattr_from_user(void *value, size_t size)
 634 {
 635         struct user_namespace *user_ns = current_user_ns();
 636         if (user_ns == &init_user_ns)
 637                 return;
 638         posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
 639 }
 640
 641 void posix_acl_fix_xattr_to_user(void *value, size_t size)
 642 {
 643         struct user_namespace *user_ns = current_user_ns();
 644         if (user_ns == &init_user_ns)
 645                 return;
 646         posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
 647 }
 648
 649 /*
 650  * Convert from extended attribute to in-memory representation.
 651  */
 652 struct posix_acl *
 653 posix_acl_from_xattr(struct user_namespace *user_ns,
 654                      const void *value, size_t size)
 655 {
 656         posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
 657         posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
 658         int count;
 659         struct posix_acl *acl;
 660         struct posix_acl_entry *acl_e;
 661
 662         if (!value)
 663                 return NULL;
 664         if (size < sizeof(posix_acl_xattr_header))
 665                  return ERR_PTR(-EINVAL);
 666         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 667                 return ERR_PTR(-EOPNOTSUPP);
 668
 669         count = posix_acl_xattr_count(size);
 670         if (count < 0)
 671                 return ERR_PTR(-EINVAL);
 672         if (count == 0)
 673                 return NULL;
 674
 675         acl = posix_acl_alloc(count, GFP_NOFS);
 676         if (!acl)
 677                 return ERR_PTR(-ENOMEM);
 678         acl_e = acl->a_entries;
 679
 680         for (end = entry + count; entry != end; acl_e++, entry++) {
 681                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
 682                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
 683
 684                 switch(acl_e->e_tag) {
 685                         case ACL_USER_OBJ:
 686                         case ACL_GROUP_OBJ:
 687                         case ACL_MASK:
 688                         case ACL_OTHER:
 689                                 break;
 690
 691                         case ACL_USER:
 692                                 acl_e->e_uid =
 693                                         make_kuid(user_ns,
 694                                                   le32_to_cpu(entry->e_id));
 695                                 if (!uid_valid(acl_e->e_uid))
 696                                         goto fail;
 697                                 break;
 698                         case ACL_GROUP:
 699                                 acl_e->e_gid =
 700                                         make_kgid(user_ns,
 701                                                   le32_to_cpu(entry->e_id));
 702                                 if (!gid_valid(acl_e->e_gid))
 703                                         goto fail;
 704                                 break;
 705
 706                         default:
 707                                 goto fail;
 708                 }
 709         }
 710         return acl;
 711
 712 fail:
 713         posix_acl_release(acl);
 714         return ERR_PTR(-EINVAL);
 715 }
 716 EXPORT_SYMBOL (posix_acl_from_xattr);
 717
 718 /*
 719  * Convert from in-memory to extended attribute representation.
 720  */
 721 int
 722 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
 723                    void *buffer, size_t size)
 724 {
 725         posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
 726         posix_acl_xattr_entry *ext_entry = ext_acl->a_entries;
 727         int real_size, n;
 728
 729         real_size = posix_acl_xattr_size(acl->a_count);
 730         if (!buffer)
 731                 return real_size;
 732         if (real_size > size)
 733                 return -ERANGE;
 734
 735         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
 736
 737         for (n=0; n < acl->a_count; n++, ext_entry++) {
 738                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 739                 ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 740                 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
 741                 switch(acl_e->e_tag) {
 742                 case ACL_USER:
 743                         ext_entry->e_id =
 744                                 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
 745                         break;
 746                 case ACL_GROUP:
 747                         ext_entry->e_id =
 748                                 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
 749                         break;
 750                 default:
 751                         ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
 752                         break;
 753                 }
 754         }
 755         return real_size;
 756 }
 757 EXPORT_SYMBOL (posix_acl_to_xattr);
 758
 759 static int
 760 posix_acl_xattr_get(struct dentry *dentry, const char *name,
 761                 void *value, size_t size, int type)
 762 {
 763         struct posix_acl *acl;
 764         int error;
 765
 766         if (!IS_POSIXACL(dentry->d_inode))
 767                 return -EOPNOTSUPP;
 768         if (S_ISLNK(dentry->d_inode->i_mode))
 769                 return -EOPNOTSUPP;
 770
 771         acl = get_acl(dentry->d_inode, type);
 772         if (IS_ERR(acl))
 773                 return PTR_ERR(acl);
 774         if (acl == NULL)
 775                 return -ENODATA;
 776
 777         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 778         posix_acl_release(acl);
 779
 780         return error;
 781 }
 782
 783 static int
 784 posix_acl_xattr_set(struct dentry *dentry, const char *name,
 785                 const void *value, size_t size, int flags, int type)
 786 {
 787         struct inode *inode = dentry->d_inode;
 788         struct posix_acl *acl = NULL;
 789         int ret;
 790
 791         if (!IS_POSIXACL(inode))
 792                 return -EOPNOTSUPP;
 793         if (!inode->i_op->set_acl)
 794                 return -EOPNOTSUPP;
 795
 796         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 797                 return value ? -EACCES : 0;
 798         if (!inode_owner_or_capable(inode))
 799                 return -EPERM;
 800
 801         if (value) {
 802                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 803                 if (IS_ERR(acl))
 804                         return PTR_ERR(acl);
 805
 806                 if (acl) {
 807                         ret = posix_acl_valid(acl);
 808                         if (ret)
 809                                 goto out;
 810                 }
 811         }
 812
 813         ret = inode->i_op->set_acl(inode, acl, type);
 814 out:
 815         posix_acl_release(acl);
 816         return ret;
 817 }
 818
 819 static size_t
 820 posix_acl_xattr_list(struct dentry *dentry, char *list, size_t list_size,
 821                 const char *name, size_t name_len, int type)
 822 {
 823         const char *xname;
 824         size_t size;
 825
 826         if (!IS_POSIXACL(dentry->d_inode))
 827                 return -EOPNOTSUPP;
 828         if (S_ISLNK(dentry->d_inode->i_mode))
 829                 return -EOPNOTSUPP;
 830
 831         if (type == ACL_TYPE_ACCESS)
 832                 xname = POSIX_ACL_XATTR_ACCESS;
 833         else
 834                 xname = POSIX_ACL_XATTR_DEFAULT;
 835
 836         size = strlen(xname) + 1;
 837         if (list && size <= list_size)
 838                 memcpy(list, xname, size);
 839         return size;
 840 }
 841
 842 const struct xattr_handler posix_acl_access_xattr_handler = {
 843         .prefix = POSIX_ACL_XATTR_ACCESS,
 844         .flags = ACL_TYPE_ACCESS,
 845         .list = posix_acl_xattr_list,
 846         .get = posix_acl_xattr_get,
 847         .set = posix_acl_xattr_set,
 848 };
 849 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
 850
 851 const struct xattr_handler posix_acl_default_xattr_handler = {
 852         .prefix = POSIX_ACL_XATTR_DEFAULT,
 853         .flags = ACL_TYPE_DEFAULT,
 854         .list = posix_acl_xattr_list,
 855         .get = posix_acl_xattr_get,
 856         .set = posix_acl_xattr_set,
 857 };
 858 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
 859
 860 int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 861 {
 862         int error;
 863
 864         if (type == ACL_TYPE_ACCESS) {
 865                 error = posix_acl_equiv_mode(acl, &inode->i_mode);
 866                 if (error < 0)
 867                         return 0;
 868                 if (error == 0)
 869                         acl = NULL;
 870         }
 871
 872         inode->i_ctime = CURRENT_TIME;
 873         set_cached_acl(inode, type, acl);
 874         return 0;
 875 }
 876
 877 int simple_acl_create(struct inode *dir, struct inode *inode)
 878 {
 879         struct posix_acl *default_acl, *acl;
 880         int error;
 881
 882         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 883         if (error)
 884                 return error;
 885
 886         set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
 887         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 888
 889         if (default_acl)
 890                 posix_acl_release(default_acl);
 891         if (acl)
 892                 posix_acl_release(acl);
 893         return 0;
 894 }