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(struct user_namespace *user_ns, 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 (!kuid_has_mapping(user_ns, 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 (!kgid_has_mapping(user_ns, 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         /*
 250          * A null ACL can always be presented as mode bits.
 251          */
 252         if (!acl)
 253                 return 0;
 254
 255         FOREACH_ACL_ENTRY(pa, acl, pe) {
 256                 switch (pa->e_tag) {
 257                         case ACL_USER_OBJ:
 258                                 mode |= (pa->e_perm & S_IRWXO) << 6;
 259                                 break;
 260                         case ACL_GROUP_OBJ:
 261                                 mode |= (pa->e_perm & S_IRWXO) << 3;
 262                                 break;
 263                         case ACL_OTHER:
 264                                 mode |= pa->e_perm & S_IRWXO;
 265                                 break;
 266                         case ACL_MASK:
 267                                 mode = (mode & ~S_IRWXG) |
 268                                        ((pa->e_perm & S_IRWXO) << 3);
 269                                 not_equiv = 1;
 270                                 break;
 271                         case ACL_USER:
 272                         case ACL_GROUP:
 273                                 not_equiv = 1;
 274                                 break;
 275                         default:
 276                                 return -EINVAL;
 277                 }
 278         }
 279         if (mode_p)
 280                 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 281         return not_equiv;
 282 }
 283 EXPORT_SYMBOL(posix_acl_equiv_mode);
 284
 285 /*
 286  * Create an ACL representing the file mode permission bits of an inode.
 287  */
 288 struct posix_acl *
 289 posix_acl_from_mode(umode_t mode, gfp_t flags)
 290 {
 291         struct posix_acl *acl = posix_acl_alloc(3, flags);
 292         if (!acl)
 293                 return ERR_PTR(-ENOMEM);
 294
 295         acl->a_entries[0].e_tag  = ACL_USER_OBJ;
 296         acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
 297
 298         acl->a_entries[1].e_tag  = ACL_GROUP_OBJ;
 299         acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
 300
 301         acl->a_entries[2].e_tag  = ACL_OTHER;
 302         acl->a_entries[2].e_perm = (mode & S_IRWXO);
 303         return acl;
 304 }
 305 EXPORT_SYMBOL(posix_acl_from_mode);
 306
 307 /*
 308  * Return 0 if current is granted want access to the inode
 309  * by the acl. Returns -E... otherwise.
 310  */
 311 int
 312 posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
 313 {
 314         const struct posix_acl_entry *pa, *pe, *mask_obj;
 315         int found = 0;
 316
 317         want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
 318
 319         FOREACH_ACL_ENTRY(pa, acl, pe) {
 320                 switch(pa->e_tag) {
 321                         case ACL_USER_OBJ:
 322                                 /* (May have been checked already) */
 323                                 if (uid_eq(inode->i_uid, current_fsuid()))
 324                                         goto check_perm;
 325                                 break;
 326                         case ACL_USER:
 327                                 if (uid_eq(pa->e_uid, current_fsuid()))
 328                                         goto mask;
 329                                 break;
 330                         case ACL_GROUP_OBJ:
 331                                 if (in_group_p(inode->i_gid)) {
 332                                         found = 1;
 333                                         if ((pa->e_perm & want) == want)
 334                                                 goto mask;
 335                                 }
 336                                 break;
 337                         case ACL_GROUP:
 338                                 if (in_group_p(pa->e_gid)) {
 339                                         found = 1;
 340                                         if ((pa->e_perm & want) == want)
 341                                                 goto mask;
 342                                 }
 343                                 break;
 344                         case ACL_MASK:
 345                                 break;
 346                         case ACL_OTHER:
 347                                 if (found)
 348                                         return -EACCES;
 349                                 else
 350                                         goto check_perm;
 351                         default:
 352                                 return -EIO;
 353                 }
 354         }
 355         return -EIO;
 356
 357 mask:
 358         for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
 359                 if (mask_obj->e_tag == ACL_MASK) {
 360                         if ((pa->e_perm & mask_obj->e_perm & want) == want)
 361                                 return 0;
 362                         return -EACCES;
 363                 }
 364         }
 365
 366 check_perm:
 367         if ((pa->e_perm & want) == want)
 368                 return 0;
 369         return -EACCES;
 370 }
 371
 372 /*
 373  * Modify acl when creating a new inode. The caller must ensure the acl is
 374  * only referenced once.
 375  *
 376  * mode_p initially must contain the mode parameter to the open() / creat()
 377  * system calls. All permissions that are not granted by the acl are removed.
 378  * The permissions in the acl are changed to reflect the mode_p parameter.
 379  */
 380 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
 381 {
 382         struct posix_acl_entry *pa, *pe;
 383         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 384         umode_t mode = *mode_p;
 385         int not_equiv = 0;
 386
 387         /* assert(atomic_read(acl->a_refcount) == 1); */
 388
 389         FOREACH_ACL_ENTRY(pa, acl, pe) {
 390                 switch(pa->e_tag) {
 391                         case ACL_USER_OBJ:
 392                                 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
 393                                 mode &= (pa->e_perm << 6) | ~S_IRWXU;
 394                                 break;
 395
 396                         case ACL_USER:
 397                         case ACL_GROUP:
 398                                 not_equiv = 1;
 399                                 break;
 400
 401                         case ACL_GROUP_OBJ:
 402                                 group_obj = pa;
 403                                 break;
 404
 405                         case ACL_OTHER:
 406                                 pa->e_perm &= mode | ~S_IRWXO;
 407                                 mode &= pa->e_perm | ~S_IRWXO;
 408                                 break;
 409
 410                         case ACL_MASK:
 411                                 mask_obj = pa;
 412                                 not_equiv = 1;
 413                                 break;
 414
 415                         default:
 416                                 return -EIO;
 417                 }
 418         }
 419
 420         if (mask_obj) {
 421                 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 422                 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
 423         } else {
 424                 if (!group_obj)
 425                         return -EIO;
 426                 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 427                 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
 428         }
 429
 430         *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 431         return not_equiv;
 432 }
 433
 434 /*
 435  * Modify the ACL for the chmod syscall.
 436  */
 437 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
 438 {
 439         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 440         struct posix_acl_entry *pa, *pe;
 441
 442         /* assert(atomic_read(acl->a_refcount) == 1); */
 443
 444         FOREACH_ACL_ENTRY(pa, acl, pe) {
 445                 switch(pa->e_tag) {
 446                         case ACL_USER_OBJ:
 447                                 pa->e_perm = (mode & S_IRWXU) >> 6;
 448                                 break;
 449
 450                         case ACL_USER:
 451                         case ACL_GROUP:
 452                                 break;
 453
 454                         case ACL_GROUP_OBJ:
 455                                 group_obj = pa;
 456                                 break;
 457
 458                         case ACL_MASK:
 459                                 mask_obj = pa;
 460                                 break;
 461
 462                         case ACL_OTHER:
 463                                 pa->e_perm = (mode & S_IRWXO);
 464                                 break;
 465
 466                         default:
 467                                 return -EIO;
 468                 }
 469         }
 470
 471         if (mask_obj) {
 472                 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
 473         } else {
 474                 if (!group_obj)
 475                         return -EIO;
 476                 group_obj->e_perm = (mode & S_IRWXG) >> 3;
 477         }
 478
 479         return 0;
 480 }
 481
 482 int
 483 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
 484 {
 485         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 486         int err = -ENOMEM;
 487         if (clone) {
 488                 err = posix_acl_create_masq(clone, mode_p);
 489                 if (err < 0) {
 490                         posix_acl_release(clone);
 491                         clone = NULL;
 492                 }
 493         }
 494         posix_acl_release(*acl);
 495         *acl = clone;
 496         return err;
 497 }
 498 EXPORT_SYMBOL(__posix_acl_create);
 499
 500 int
 501 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
 502 {
 503         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 504         int err = -ENOMEM;
 505         if (clone) {
 506                 err = __posix_acl_chmod_masq(clone, mode);
 507                 if (err) {
 508                         posix_acl_release(clone);
 509                         clone = NULL;
 510                 }
 511         }
 512         posix_acl_release(*acl);
 513         *acl = clone;
 514         return err;
 515 }
 516 EXPORT_SYMBOL(__posix_acl_chmod);
 517
 518 int
 519 posix_acl_chmod(struct inode *inode, umode_t mode)
 520 {
 521         struct posix_acl *acl;
 522         int ret = 0;
 523
 524         if (!IS_POSIXACL(inode))
 525                 return 0;
 526         if (!inode->i_op->set_acl)
 527                 return -EOPNOTSUPP;
 528
 529         acl = get_acl(inode, ACL_TYPE_ACCESS);
 530         if (IS_ERR_OR_NULL(acl)) {
 531                 if (acl == ERR_PTR(-EOPNOTSUPP))
 532                         return 0;
 533                 return PTR_ERR(acl);
 534         }
 535
 536         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 537         if (ret)
 538                 return ret;
 539         ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
 540         posix_acl_release(acl);
 541         return ret;
 542 }
 543 EXPORT_SYMBOL(posix_acl_chmod);
 544
 545 int
 546 posix_acl_create(struct inode *dir, umode_t *mode,
 547                 struct posix_acl **default_acl, struct posix_acl **acl)
 548 {
 549         struct posix_acl *p;
 550         struct posix_acl *clone;
 551         int ret;
 552
 553         *acl = NULL;
 554         *default_acl = NULL;
 555
 556         if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
 557                 return 0;
 558
 559         p = get_acl(dir, ACL_TYPE_DEFAULT);
 560         if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
 561                 *mode &= ~current_umask();
 562                 return 0;
 563         }
 564         if (IS_ERR(p))
 565                 return PTR_ERR(p);
 566
 567         clone = posix_acl_clone(p, GFP_NOFS);
 568         if (!clone)
 569                 goto no_mem;
 570
 571         ret = posix_acl_create_masq(clone, mode);
 572         if (ret < 0)
 573                 goto no_mem_clone;
 574
 575         if (ret == 0)
 576                 posix_acl_release(clone);
 577         else
 578                 *acl = clone;
 579
 580         if (!S_ISDIR(*mode))
 581                 posix_acl_release(p);
 582         else
 583                 *default_acl = p;
 584
 585         return 0;
 586
 587 no_mem_clone:
 588         posix_acl_release(clone);
 589 no_mem:
 590         posix_acl_release(p);
 591         return -ENOMEM;
 592 }
 593 EXPORT_SYMBOL_GPL(posix_acl_create);
 594
 595 /**
 596  * posix_acl_update_mode  -  update mode in set_acl
 597  *
 598  * Update the file mode when setting an ACL: compute the new file permission
 599  * bits based on the ACL.  In addition, if the ACL is equivalent to the new
 600  * file mode, set *acl to NULL to indicate that no ACL should be set.
 601  *
 602  * As with chmod, clear the setgit bit if the caller is not in the owning group
 603  * or capable of CAP_FSETID (see inode_change_ok).
 604  *
 605  * Called from set_acl inode operations.
 606  */
 607 int posix_acl_update_mode(struct inode *inode, umode_t *mode_p,
 608                           struct posix_acl **acl)
 609 {
 610         umode_t mode = inode->i_mode;
 611         int error;
 612
 613         error = posix_acl_equiv_mode(*acl, &mode);
 614         if (error < 0)
 615                 return error;
 616         if (error == 0)
 617                 *acl = NULL;
 618         if (!in_group_p(inode->i_gid) &&
 619             !capable_wrt_inode_uidgid(inode, CAP_FSETID))
 620                 mode &= ~S_ISGID;
 621         *mode_p = mode;
 622         return 0;
 623 }
 624 EXPORT_SYMBOL(posix_acl_update_mode);
 625
 626 /*
 627  * Fix up the uids and gids in posix acl extended attributes in place.
 628  */
 629 int posix_acl_fix_xattr_userns(
 630         struct user_namespace *to, struct user_namespace *from,
 631         void *value, size_t size)
 632 {
 633         posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
 634         posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
 635         int count;
 636         kuid_t kuid;
 637         kgid_t kgid;
 638         uid_t uid;
 639         gid_t gid;
 640         int ret = 0;
 641
 642         if (to == from)
 643                 return 0;
 644         if (!value)
 645                 return 0;
 646         if (size < sizeof(posix_acl_xattr_header))
 647                 return -EINVAL;
 648         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 649                 return -EINVAL;
 650
 651         count = posix_acl_xattr_count(size);
 652         if (count < 0)
 653                 return -EINVAL;
 654         if (count == 0)
 655                 return 0;
 656
 657         for (end = entry + count; entry != end; entry++) {
 658                 switch(le16_to_cpu(entry->e_tag)) {
 659                 case ACL_USER:
 660                         kuid = make_kuid(from, le32_to_cpu(entry->e_id));
 661                         uid = from_kuid(to, kuid);
 662                         entry->e_id = cpu_to_le32(uid);
 663                         if (uid == (uid_t)-1)
 664                                 ret = -EOVERFLOW;
 665                         break;
 666                 case ACL_GROUP:
 667                         kgid = make_kgid(from, le32_to_cpu(entry->e_id));
 668                         gid = from_kgid(to, kgid);
 669                         entry->e_id = cpu_to_le32(gid);
 670                         if (gid == (gid_t)-1)
 671                                 ret = -EOVERFLOW;
 672                         break;
 673                 default:
 674                         break;
 675                 }
 676         }
 677
 678         return ret;
 679 }
 680 EXPORT_SYMBOL(posix_acl_fix_xattr_userns);
 681
 682 void posix_acl_fix_xattr_from_user(void *value, size_t size)
 683 {
 684         struct user_namespace *user_ns = current_user_ns();
 685         posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
 686 }
 687
 688 void posix_acl_fix_xattr_to_user(void *value, size_t size)
 689 {
 690         struct user_namespace *user_ns = current_user_ns();
 691         posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
 692 }
 693
 694 /*
 695  * Convert from extended attribute to in-memory representation.
 696  */
 697 struct posix_acl *
 698 posix_acl_from_xattr(struct user_namespace *user_ns,
 699                      const void *value, size_t size)
 700 {
 701         posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
 702         posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
 703         int count;
 704         struct posix_acl *acl;
 705         struct posix_acl_entry *acl_e;
 706
 707         if (!value)
 708                 return NULL;
 709         if (size < sizeof(posix_acl_xattr_header))
 710                  return ERR_PTR(-EINVAL);
 711         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 712                 return ERR_PTR(-EOPNOTSUPP);
 713
 714         count = posix_acl_xattr_count(size);
 715         if (count < 0)
 716                 return ERR_PTR(-EINVAL);
 717         if (count == 0)
 718                 return NULL;
 719
 720         acl = posix_acl_alloc(count, GFP_NOFS);
 721         if (!acl)
 722                 return ERR_PTR(-ENOMEM);
 723         acl_e = acl->a_entries;
 724
 725         for (end = entry + count; entry != end; acl_e++, entry++) {
 726                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
 727                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
 728
 729                 switch(acl_e->e_tag) {
 730                         case ACL_USER_OBJ:
 731                         case ACL_GROUP_OBJ:
 732                         case ACL_MASK:
 733                         case ACL_OTHER:
 734                                 break;
 735
 736                         case ACL_USER:
 737                                 acl_e->e_uid =
 738                                         make_kuid(user_ns,
 739                                                   le32_to_cpu(entry->e_id));
 740                                 if (!uid_valid(acl_e->e_uid))
 741                                         goto fail;
 742                                 break;
 743                         case ACL_GROUP:
 744                                 acl_e->e_gid =
 745                                         make_kgid(user_ns,
 746                                                   le32_to_cpu(entry->e_id));
 747                                 if (!gid_valid(acl_e->e_gid))
 748                                         goto fail;
 749                                 break;
 750
 751                         default:
 752                                 goto fail;
 753                 }
 754         }
 755         return acl;
 756
 757 fail:
 758         posix_acl_release(acl);
 759         return ERR_PTR(-EINVAL);
 760 }
 761 EXPORT_SYMBOL (posix_acl_from_xattr);
 762
 763 /*
 764  * Convert from in-memory to extended attribute representation.
 765  */
 766 int
 767 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
 768                    void *buffer, size_t size)
 769 {
 770         posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
 771         posix_acl_xattr_entry *ext_entry;
 772         int real_size, n;
 773
 774         real_size = posix_acl_xattr_size(acl->a_count);
 775         if (!buffer)
 776                 return real_size;
 777         if (real_size > size)
 778                 return -ERANGE;
 779
 780         ext_entry = ext_acl->a_entries;
 781         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
 782
 783         for (n=0; n < acl->a_count; n++, ext_entry++) {
 784                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 785                 ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 786                 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
 787                 switch(acl_e->e_tag) {
 788                 case ACL_USER:
 789                         ext_entry->e_id =
 790                                 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
 791                         break;
 792                 case ACL_GROUP:
 793                         ext_entry->e_id =
 794                                 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
 795                         break;
 796                 default:
 797                         ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
 798                         break;
 799                 }
 800         }
 801         return real_size;
 802 }
 803 EXPORT_SYMBOL (posix_acl_to_xattr);
 804
 805 static int
 806 posix_acl_xattr_get(const struct xattr_handler *handler,
 807                     struct dentry *dentry, const char *name,
 808                     void *value, size_t size)
 809 {
 810         struct posix_acl *acl;
 811         int error;
 812
 813         if (strcmp(name, "") != 0)
 814                 return -EINVAL;
 815         if (!IS_POSIXACL(d_backing_inode(dentry)))
 816                 return -EOPNOTSUPP;
 817         if (d_is_symlink(dentry))
 818                 return -EOPNOTSUPP;
 819
 820         acl = get_acl(d_backing_inode(dentry), handler->flags);
 821         if (IS_ERR(acl))
 822                 return PTR_ERR(acl);
 823         if (acl == NULL)
 824                 return -ENODATA;
 825
 826         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 827         posix_acl_release(acl);
 828
 829         return error;
 830 }
 831
 832 int
 833 set_posix_acl(struct inode *inode, int type, struct posix_acl *acl)
 834 {
 835         if (!IS_POSIXACL(inode))
 836                 return -EOPNOTSUPP;
 837         if (!inode->i_op->set_acl)
 838                 return -EOPNOTSUPP;
 839
 840         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 841                 return acl ? -EACCES : 0;
 842         if (!inode_owner_or_capable(inode))
 843                 return -EPERM;
 844
 845         if (acl) {
 846                 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
 847                 if (ret)
 848                         return ret;
 849         }
 850         return inode->i_op->set_acl(inode, acl, type);
 851 }
 852 EXPORT_SYMBOL(set_posix_acl);
 853
 854 static int
 855 posix_acl_xattr_set(const struct xattr_handler *handler,
 856                     struct dentry *dentry, const char *name,
 857                     const void *value, size_t size, int flags)
 858 {
 859         struct inode *inode = d_backing_inode(dentry);
 860         struct posix_acl *acl = NULL;
 861         int ret;
 862
 863         if (strcmp(name, "") != 0)
 864                 return -EINVAL;
 865
 866         if (value) {
 867                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 868                 if (IS_ERR(acl))
 869                         return PTR_ERR(acl);
 870         }
 871         ret = set_posix_acl(inode, handler->flags, acl);
 872         posix_acl_release(acl);
 873         return ret;
 874 }
 875
 876 static size_t
 877 posix_acl_xattr_list(const struct xattr_handler *handler,
 878                      struct dentry *dentry, char *list, size_t list_size,
 879                      const char *name, size_t name_len)
 880 {
 881         const char *xname = handler->prefix;
 882         size_t size;
 883
 884         if (!IS_POSIXACL(d_backing_inode(dentry)))
 885                 return 0;
 886
 887         size = strlen(xname) + 1;
 888         if (list && size <= list_size)
 889                 memcpy(list, xname, size);
 890         return size;
 891 }
 892
 893 const struct xattr_handler posix_acl_access_xattr_handler = {
 894         .prefix = POSIX_ACL_XATTR_ACCESS,
 895         .flags = ACL_TYPE_ACCESS,
 896         .list = posix_acl_xattr_list,
 897         .get = posix_acl_xattr_get,
 898         .set = posix_acl_xattr_set,
 899 };
 900 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
 901
 902 const struct xattr_handler posix_acl_default_xattr_handler = {
 903         .prefix = POSIX_ACL_XATTR_DEFAULT,
 904         .flags = ACL_TYPE_DEFAULT,
 905         .list = posix_acl_xattr_list,
 906         .get = posix_acl_xattr_get,
 907         .set = posix_acl_xattr_set,
 908 };
 909 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
 910
 911 int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 912 {
 913         int error;
 914
 915         if (type == ACL_TYPE_ACCESS) {
 916                 error = posix_acl_update_mode(inode,
 917                                 &inode->i_mode, &acl);
 918                 if (error)
 919                         return error;
 920         }
 921
 922         inode->i_ctime = CURRENT_TIME;
 923         set_cached_acl(inode, type, acl);
 924         return 0;
 925 }
 926
 927 int simple_acl_create(struct inode *dir, struct inode *inode)
 928 {
 929         struct posix_acl *default_acl, *acl;
 930         int error;
 931
 932         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 933         if (error)
 934                 return error;
 935
 936         set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
 937         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 938
 939         if (default_acl)
 940                 posix_acl_release(default_acl);
 941         if (acl)
 942                 posix_acl_release(acl);
 943         return 0;
 944 }