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/cred.h>
  19 #include <linux/posix_acl.h>
  20 #include <linux/posix_acl_xattr.h>
  21 #include <linux/xattr.h>
  22 #include <linux/export.h>
  23 #include <linux/user_namespace.h>
  24
  25 static struct posix_acl **acl_by_type(struct inode *inode, int type)
  26 {
  27         switch (type) {
  28         case ACL_TYPE_ACCESS:
  29                 return &inode->i_acl;
  30         case ACL_TYPE_DEFAULT:
  31                 return &inode->i_default_acl;
  32         default:
  33                 BUG();
  34         }
  35 }
  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;
  41
  42         for (;;) {
  43                 rcu_read_lock();
  44                 acl = rcu_dereference(*p);
  45                 if (!acl || is_uncached_acl(acl) ||
  46                     refcount_inc_not_zero(&acl->a_refcount))
  47                         break;
  48                 rcu_read_unlock();
  49                 cpu_relax();
  50         }
  51         rcu_read_unlock();
  52         return acl;
  53 }
  54 EXPORT_SYMBOL(get_cached_acl);
  55
  56 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
  57 {
  58         return rcu_dereference(*acl_by_type(inode, type));
  59 }
  60 EXPORT_SYMBOL(get_cached_acl_rcu);
  61
  62 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
  63 {
  64         struct posix_acl **p = acl_by_type(inode, type);
  65         struct posix_acl *old;
  66
  67         old = xchg(p, posix_acl_dup(acl));
  68         if (!is_uncached_acl(old))
  69                 posix_acl_release(old);
  70 }
  71 EXPORT_SYMBOL(set_cached_acl);
  72
  73 static void __forget_cached_acl(struct posix_acl **p)
  74 {
  75         struct posix_acl *old;
  76
  77         old = xchg(p, ACL_NOT_CACHED);
  78         if (!is_uncached_acl(old))
  79                 posix_acl_release(old);
  80 }
  81
  82 void forget_cached_acl(struct inode *inode, int type)
  83 {
  84         __forget_cached_acl(acl_by_type(inode, type));
  85 }
  86 EXPORT_SYMBOL(forget_cached_acl);
  87
  88 void forget_all_cached_acls(struct inode *inode)
  89 {
  90         __forget_cached_acl(&inode->i_acl);
  91         __forget_cached_acl(&inode->i_default_acl);
  92 }
  93 EXPORT_SYMBOL(forget_all_cached_acls);
  94
  95 struct posix_acl *get_acl(struct inode *inode, int type)
  96 {
  97         void *sentinel;
  98         struct posix_acl **p;
  99         struct posix_acl *acl;
 100
 101         /*
 102          * The sentinel is used to detect when another operation like
 103          * set_cached_acl() or forget_cached_acl() races with get_acl().
 104          * It is guaranteed that is_uncached_acl(sentinel) is true.
 105          */
 106
 107         acl = get_cached_acl(inode, type);
 108         if (!is_uncached_acl(acl))
 109                 return acl;
 110
 111         if (!IS_POSIXACL(inode))
 112                 return NULL;
 113
 114         sentinel = uncached_acl_sentinel(current);
 115         p = acl_by_type(inode, type);
 116
 117         /*
 118          * If the ACL isn't being read yet, set our sentinel.  Otherwise, the
 119          * current value of the ACL will not be ACL_NOT_CACHED and so our own
 120          * sentinel will not be set; another task will update the cache.  We
 121          * could wait for that other task to complete its job, but it's easier
 122          * to just call ->get_acl to fetch the ACL ourself.  (This is going to
 123          * be an unlikely race.)
 124          */
 125         if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED)
 126                 /* fall through */ ;
 127
 128         /*
 129          * Normally, the ACL returned by ->get_acl will be cached.
 130          * A filesystem can prevent that by calling
 131          * forget_cached_acl(inode, type) in ->get_acl.
 132          *
 133          * If the filesystem doesn't have a get_acl() function at all, we'll
 134          * just create the negative cache entry.
 135          */
 136         if (!inode->i_op->get_acl) {
 137                 set_cached_acl(inode, type, NULL);
 138                 return NULL;
 139         }
 140         acl = inode->i_op->get_acl(inode, type);
 141
 142         if (IS_ERR(acl)) {
 143                 /*
 144                  * Remove our sentinel so that we don't block future attempts
 145                  * to cache the ACL.
 146                  */
 147                 cmpxchg(p, sentinel, ACL_NOT_CACHED);
 148                 return acl;
 149         }
 150
 151         /*
 152          * Cache the result, but only if our sentinel is still in place.
 153          */
 154         posix_acl_dup(acl);
 155         if (unlikely(cmpxchg(p, sentinel, acl) != sentinel))
 156                 posix_acl_release(acl);
 157         return acl;
 158 }
 159 EXPORT_SYMBOL(get_acl);
 160
 161 /*
 162  * Init a fresh posix_acl
 163  */
 164 void
 165 posix_acl_init(struct posix_acl *acl, int count)
 166 {
 167         refcount_set(&acl->a_refcount, 1);
 168         acl->a_count = count;
 169 }
 170 EXPORT_SYMBOL(posix_acl_init);
 171
 172 /*
 173  * Allocate a new ACL with the specified number of entries.
 174  */
 175 struct posix_acl *
 176 posix_acl_alloc(int count, gfp_t flags)
 177 {
 178         const size_t size = sizeof(struct posix_acl) +
 179                             count * sizeof(struct posix_acl_entry);
 180         struct posix_acl *acl = kmalloc(size, flags);
 181         if (acl)
 182                 posix_acl_init(acl, count);
 183         return acl;
 184 }
 185 EXPORT_SYMBOL(posix_acl_alloc);
 186
 187 /*
 188  * Clone an ACL.
 189  */
 190 static struct posix_acl *
 191 posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
 192 {
 193         struct posix_acl *clone = NULL;
 194
 195         if (acl) {
 196                 int size = sizeof(struct posix_acl) + acl->a_count *
 197                            sizeof(struct posix_acl_entry);
 198                 clone = kmemdup(acl, size, flags);
 199                 if (clone)
 200                         refcount_set(&clone->a_refcount, 1);
 201         }
 202         return clone;
 203 }
 204
 205 /*
 206  * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
 207  */
 208 int
 209 posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl)
 210 {
 211         const struct posix_acl_entry *pa, *pe;
 212         int state = ACL_USER_OBJ;
 213         int needs_mask = 0;
 214
 215         FOREACH_ACL_ENTRY(pa, acl, pe) {
 216                 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
 217                         return -EINVAL;
 218                 switch (pa->e_tag) {
 219                         case ACL_USER_OBJ:
 220                                 if (state == ACL_USER_OBJ) {
 221                                         state = ACL_USER;
 222                                         break;
 223                                 }
 224                                 return -EINVAL;
 225
 226                         case ACL_USER:
 227                                 if (state != ACL_USER)
 228                                         return -EINVAL;
 229                                 if (!kuid_has_mapping(user_ns, pa->e_uid))
 230                                         return -EINVAL;
 231                                 needs_mask = 1;
 232                                 break;
 233
 234                         case ACL_GROUP_OBJ:
 235                                 if (state == ACL_USER) {
 236                                         state = ACL_GROUP;
 237                                         break;
 238                                 }
 239                                 return -EINVAL;
 240
 241                         case ACL_GROUP:
 242                                 if (state != ACL_GROUP)
 243                                         return -EINVAL;
 244                                 if (!kgid_has_mapping(user_ns, pa->e_gid))
 245                                         return -EINVAL;
 246                                 needs_mask = 1;
 247                                 break;
 248
 249                         case ACL_MASK:
 250                                 if (state != ACL_GROUP)
 251                                         return -EINVAL;
 252                                 state = ACL_OTHER;
 253                                 break;
 254
 255                         case ACL_OTHER:
 256                                 if (state == ACL_OTHER ||
 257                                     (state == ACL_GROUP && !needs_mask)) {
 258                                         state = 0;
 259                                         break;
 260                                 }
 261                                 return -EINVAL;
 262
 263                         default:
 264                                 return -EINVAL;
 265                 }
 266         }
 267         if (state == 0)
 268                 return 0;
 269         return -EINVAL;
 270 }
 271 EXPORT_SYMBOL(posix_acl_valid);
 272
 273 /*
 274  * Returns 0 if the acl can be exactly represented in the traditional
 275  * file mode permission bits, or else 1. Returns -E... on error.
 276  */
 277 int
 278 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
 279 {
 280         const struct posix_acl_entry *pa, *pe;
 281         umode_t mode = 0;
 282         int not_equiv = 0;
 283
 284         /*
 285          * A null ACL can always be presented as mode bits.
 286          */
 287         if (!acl)
 288                 return 0;
 289
 290         FOREACH_ACL_ENTRY(pa, acl, pe) {
 291                 switch (pa->e_tag) {
 292                         case ACL_USER_OBJ:
 293                                 mode |= (pa->e_perm & S_IRWXO) << 6;
 294                                 break;
 295                         case ACL_GROUP_OBJ:
 296                                 mode |= (pa->e_perm & S_IRWXO) << 3;
 297                                 break;
 298                         case ACL_OTHER:
 299                                 mode |= pa->e_perm & S_IRWXO;
 300                                 break;
 301                         case ACL_MASK:
 302                                 mode = (mode & ~S_IRWXG) |
 303                                        ((pa->e_perm & S_IRWXO) << 3);
 304                                 not_equiv = 1;
 305                                 break;
 306                         case ACL_USER:
 307                         case ACL_GROUP:
 308                                 not_equiv = 1;
 309                                 break;
 310                         default:
 311                                 return -EINVAL;
 312                 }
 313         }
 314         if (mode_p)
 315                 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 316         return not_equiv;
 317 }
 318 EXPORT_SYMBOL(posix_acl_equiv_mode);
 319
 320 /*
 321  * Create an ACL representing the file mode permission bits of an inode.
 322  */
 323 struct posix_acl *
 324 posix_acl_from_mode(umode_t mode, gfp_t flags)
 325 {
 326         struct posix_acl *acl = posix_acl_alloc(3, flags);
 327         if (!acl)
 328                 return ERR_PTR(-ENOMEM);
 329
 330         acl->a_entries[0].e_tag  = ACL_USER_OBJ;
 331         acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
 332
 333         acl->a_entries[1].e_tag  = ACL_GROUP_OBJ;
 334         acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
 335
 336         acl->a_entries[2].e_tag  = ACL_OTHER;
 337         acl->a_entries[2].e_perm = (mode & S_IRWXO);
 338         return acl;
 339 }
 340 EXPORT_SYMBOL(posix_acl_from_mode);
 341
 342 /*
 343  * Return 0 if current is granted want access to the inode
 344  * by the acl. Returns -E... otherwise.
 345  */
 346 int
 347 posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
 348 {
 349         const struct posix_acl_entry *pa, *pe, *mask_obj;
 350         int found = 0;
 351
 352         want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
 353
 354         FOREACH_ACL_ENTRY(pa, acl, pe) {
 355                 switch(pa->e_tag) {
 356                         case ACL_USER_OBJ:
 357                                 /* (May have been checked already) */
 358                                 if (uid_eq(inode->i_uid, current_fsuid()))
 359                                         goto check_perm;
 360                                 break;
 361                         case ACL_USER:
 362                                 if (uid_eq(pa->e_uid, current_fsuid()))
 363                                         goto mask;
 364                                 break;
 365                         case ACL_GROUP_OBJ:
 366                                 if (in_group_p(inode->i_gid)) {
 367                                         found = 1;
 368                                         if ((pa->e_perm & want) == want)
 369                                                 goto mask;
 370                                 }
 371                                 break;
 372                         case ACL_GROUP:
 373                                 if (in_group_p(pa->e_gid)) {
 374                                         found = 1;
 375                                         if ((pa->e_perm & want) == want)
 376                                                 goto mask;
 377                                 }
 378                                 break;
 379                         case ACL_MASK:
 380                                 break;
 381                         case ACL_OTHER:
 382                                 if (found)
 383                                         return -EACCES;
 384                                 else
 385                                         goto check_perm;
 386                         default:
 387                                 return -EIO;
 388                 }
 389         }
 390         return -EIO;
 391
 392 mask:
 393         for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
 394                 if (mask_obj->e_tag == ACL_MASK) {
 395                         if ((pa->e_perm & mask_obj->e_perm & want) == want)
 396                                 return 0;
 397                         return -EACCES;
 398                 }
 399         }
 400
 401 check_perm:
 402         if ((pa->e_perm & want) == want)
 403                 return 0;
 404         return -EACCES;
 405 }
 406
 407 /*
 408  * Modify acl when creating a new inode. The caller must ensure the acl is
 409  * only referenced once.
 410  *
 411  * mode_p initially must contain the mode parameter to the open() / creat()
 412  * system calls. All permissions that are not granted by the acl are removed.
 413  * The permissions in the acl are changed to reflect the mode_p parameter.
 414  */
 415 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
 416 {
 417         struct posix_acl_entry *pa, *pe;
 418         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 419         umode_t mode = *mode_p;
 420         int not_equiv = 0;
 421
 422         /* assert(atomic_read(acl->a_refcount) == 1); */
 423
 424         FOREACH_ACL_ENTRY(pa, acl, pe) {
 425                 switch(pa->e_tag) {
 426                         case ACL_USER_OBJ:
 427                                 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
 428                                 mode &= (pa->e_perm << 6) | ~S_IRWXU;
 429                                 break;
 430
 431                         case ACL_USER:
 432                         case ACL_GROUP:
 433                                 not_equiv = 1;
 434                                 break;
 435
 436                         case ACL_GROUP_OBJ:
 437                                 group_obj = pa;
 438                                 break;
 439
 440                         case ACL_OTHER:
 441                                 pa->e_perm &= mode | ~S_IRWXO;
 442                                 mode &= pa->e_perm | ~S_IRWXO;
 443                                 break;
 444
 445                         case ACL_MASK:
 446                                 mask_obj = pa;
 447                                 not_equiv = 1;
 448                                 break;
 449
 450                         default:
 451                                 return -EIO;
 452                 }
 453         }
 454
 455         if (mask_obj) {
 456                 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 457                 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
 458         } else {
 459                 if (!group_obj)
 460                         return -EIO;
 461                 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 462                 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
 463         }
 464
 465         *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 466         return not_equiv;
 467 }
 468
 469 /*
 470  * Modify the ACL for the chmod syscall.
 471  */
 472 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
 473 {
 474         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 475         struct posix_acl_entry *pa, *pe;
 476
 477         /* assert(atomic_read(acl->a_refcount) == 1); */
 478
 479         FOREACH_ACL_ENTRY(pa, acl, pe) {
 480                 switch(pa->e_tag) {
 481                         case ACL_USER_OBJ:
 482                                 pa->e_perm = (mode & S_IRWXU) >> 6;
 483                                 break;
 484
 485                         case ACL_USER:
 486                         case ACL_GROUP:
 487                                 break;
 488
 489                         case ACL_GROUP_OBJ:
 490                                 group_obj = pa;
 491                                 break;
 492
 493                         case ACL_MASK:
 494                                 mask_obj = pa;
 495                                 break;
 496
 497                         case ACL_OTHER:
 498                                 pa->e_perm = (mode & S_IRWXO);
 499                                 break;
 500
 501                         default:
 502                                 return -EIO;
 503                 }
 504         }
 505
 506         if (mask_obj) {
 507                 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
 508         } else {
 509                 if (!group_obj)
 510                         return -EIO;
 511                 group_obj->e_perm = (mode & S_IRWXG) >> 3;
 512         }
 513
 514         return 0;
 515 }
 516
 517 int
 518 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
 519 {
 520         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 521         int err = -ENOMEM;
 522         if (clone) {
 523                 err = posix_acl_create_masq(clone, mode_p);
 524                 if (err < 0) {
 525                         posix_acl_release(clone);
 526                         clone = NULL;
 527                 }
 528         }
 529         posix_acl_release(*acl);
 530         *acl = clone;
 531         return err;
 532 }
 533 EXPORT_SYMBOL(__posix_acl_create);
 534
 535 int
 536 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
 537 {
 538         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 539         int err = -ENOMEM;
 540         if (clone) {
 541                 err = __posix_acl_chmod_masq(clone, mode);
 542                 if (err) {
 543                         posix_acl_release(clone);
 544                         clone = NULL;
 545                 }
 546         }
 547         posix_acl_release(*acl);
 548         *acl = clone;
 549         return err;
 550 }
 551 EXPORT_SYMBOL(__posix_acl_chmod);
 552
 553 int
 554 posix_acl_chmod(struct inode *inode, umode_t mode)
 555 {
 556         struct posix_acl *acl;
 557         int ret = 0;
 558
 559         if (!IS_POSIXACL(inode))
 560                 return 0;
 561         if (!inode->i_op->set_acl)
 562                 return -EOPNOTSUPP;
 563
 564         acl = get_acl(inode, ACL_TYPE_ACCESS);
 565         if (IS_ERR_OR_NULL(acl)) {
 566                 if (acl == ERR_PTR(-EOPNOTSUPP))
 567                         return 0;
 568                 return PTR_ERR(acl);
 569         }
 570
 571         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 572         if (ret)
 573                 return ret;
 574         ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
 575         posix_acl_release(acl);
 576         return ret;
 577 }
 578 EXPORT_SYMBOL(posix_acl_chmod);
 579
 580 int
 581 posix_acl_create(struct inode *dir, umode_t *mode,
 582                 struct posix_acl **default_acl, struct posix_acl **acl)
 583 {
 584         struct posix_acl *p;
 585         struct posix_acl *clone;
 586         int ret;
 587
 588         *acl = NULL;
 589         *default_acl = NULL;
 590
 591         if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
 592                 return 0;
 593
 594         p = get_acl(dir, ACL_TYPE_DEFAULT);
 595         if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
 596                 *mode &= ~current_umask();
 597                 return 0;
 598         }
 599         if (IS_ERR(p))
 600                 return PTR_ERR(p);
 601
 602         ret = -ENOMEM;
 603         clone = posix_acl_clone(p, GFP_NOFS);
 604         if (!clone)
 605                 goto err_release;
 606
 607         ret = posix_acl_create_masq(clone, mode);
 608         if (ret < 0)
 609                 goto err_release_clone;
 610
 611         if (ret == 0)
 612                 posix_acl_release(clone);
 613         else
 614                 *acl = clone;
 615
 616         if (!S_ISDIR(*mode))
 617                 posix_acl_release(p);
 618         else
 619                 *default_acl = p;
 620
 621         return 0;
 622
 623 err_release_clone:
 624         posix_acl_release(clone);
 625 err_release:
 626         posix_acl_release(p);
 627         return ret;
 628 }
 629 EXPORT_SYMBOL_GPL(posix_acl_create);
 630
 631 /**
 632  * posix_acl_update_mode  -  update mode in set_acl
 633  *
 634  * Update the file mode when setting an ACL: compute the new file permission
 635  * bits based on the ACL.  In addition, if the ACL is equivalent to the new
 636  * file mode, set *acl to NULL to indicate that no ACL should be set.
 637  *
 638  * As with chmod, clear the setgit bit if the caller is not in the owning group
 639  * or capable of CAP_FSETID (see inode_change_ok).
 640  *
 641  * Called from set_acl inode operations.
 642  */
 643 int posix_acl_update_mode(struct inode *inode, umode_t *mode_p,
 644                           struct posix_acl **acl)
 645 {
 646         umode_t mode = inode->i_mode;
 647         int error;
 648
 649         error = posix_acl_equiv_mode(*acl, &mode);
 650         if (error < 0)
 651                 return error;
 652         if (error == 0)
 653                 *acl = NULL;
 654         if (!in_group_p(inode->i_gid) &&
 655             !capable_wrt_inode_uidgid(inode, CAP_FSETID))
 656                 mode &= ~S_ISGID;
 657         *mode_p = mode;
 658         return 0;
 659 }
 660 EXPORT_SYMBOL(posix_acl_update_mode);
 661
 662 /*
 663  * Fix up the uids and gids in posix acl extended attributes in place.
 664  */
 665 static void posix_acl_fix_xattr_userns(
 666         struct user_namespace *to, struct user_namespace *from,
 667         void *value, size_t size)
 668 {
 669         struct posix_acl_xattr_header *header = value;
 670         struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
 671         int count;
 672         kuid_t uid;
 673         kgid_t gid;
 674
 675         if (!value)
 676                 return;
 677         if (size < sizeof(struct posix_acl_xattr_header))
 678                 return;
 679         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 680                 return;
 681
 682         count = posix_acl_xattr_count(size);
 683         if (count < 0)
 684                 return;
 685         if (count == 0)
 686                 return;
 687
 688         for (end = entry + count; entry != end; entry++) {
 689                 switch(le16_to_cpu(entry->e_tag)) {
 690                 case ACL_USER:
 691                         uid = make_kuid(from, le32_to_cpu(entry->e_id));
 692                         entry->e_id = cpu_to_le32(from_kuid(to, uid));
 693                         break;
 694                 case ACL_GROUP:
 695                         gid = make_kgid(from, le32_to_cpu(entry->e_id));
 696                         entry->e_id = cpu_to_le32(from_kgid(to, gid));
 697                         break;
 698                 default:
 699                         break;
 700                 }
 701         }
 702 }
 703
 704 void posix_acl_fix_xattr_from_user(void *value, size_t size)
 705 {
 706         struct user_namespace *user_ns = current_user_ns();
 707         if (user_ns == &init_user_ns)
 708                 return;
 709         posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
 710 }
 711
 712 void posix_acl_fix_xattr_to_user(void *value, size_t size)
 713 {
 714         struct user_namespace *user_ns = current_user_ns();
 715         if (user_ns == &init_user_ns)
 716                 return;
 717         posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
 718 }
 719
 720 /*
 721  * Convert from extended attribute to in-memory representation.
 722  */
 723 struct posix_acl *
 724 posix_acl_from_xattr(struct user_namespace *user_ns,
 725                      const void *value, size_t size)
 726 {
 727         const struct posix_acl_xattr_header *header = value;
 728         const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
 729         int count;
 730         struct posix_acl *acl;
 731         struct posix_acl_entry *acl_e;
 732
 733         if (!value)
 734                 return NULL;
 735         if (size < sizeof(struct posix_acl_xattr_header))
 736                  return ERR_PTR(-EINVAL);
 737         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 738                 return ERR_PTR(-EOPNOTSUPP);
 739
 740         count = posix_acl_xattr_count(size);
 741         if (count < 0)
 742                 return ERR_PTR(-EINVAL);
 743         if (count == 0)
 744                 return NULL;
 745
 746         acl = posix_acl_alloc(count, GFP_NOFS);
 747         if (!acl)
 748                 return ERR_PTR(-ENOMEM);
 749         acl_e = acl->a_entries;
 750
 751         for (end = entry + count; entry != end; acl_e++, entry++) {
 752                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
 753                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
 754
 755                 switch(acl_e->e_tag) {
 756                         case ACL_USER_OBJ:
 757                         case ACL_GROUP_OBJ:
 758                         case ACL_MASK:
 759                         case ACL_OTHER:
 760                                 break;
 761
 762                         case ACL_USER:
 763                                 acl_e->e_uid =
 764                                         make_kuid(user_ns,
 765                                                   le32_to_cpu(entry->e_id));
 766                                 if (!uid_valid(acl_e->e_uid))
 767                                         goto fail;
 768                                 break;
 769                         case ACL_GROUP:
 770                                 acl_e->e_gid =
 771                                         make_kgid(user_ns,
 772                                                   le32_to_cpu(entry->e_id));
 773                                 if (!gid_valid(acl_e->e_gid))
 774                                         goto fail;
 775                                 break;
 776
 777                         default:
 778                                 goto fail;
 779                 }
 780         }
 781         return acl;
 782
 783 fail:
 784         posix_acl_release(acl);
 785         return ERR_PTR(-EINVAL);
 786 }
 787 EXPORT_SYMBOL (posix_acl_from_xattr);
 788
 789 /*
 790  * Convert from in-memory to extended attribute representation.
 791  */
 792 int
 793 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
 794                    void *buffer, size_t size)
 795 {
 796         struct posix_acl_xattr_header *ext_acl = buffer;
 797         struct posix_acl_xattr_entry *ext_entry;
 798         int real_size, n;
 799
 800         real_size = posix_acl_xattr_size(acl->a_count);
 801         if (!buffer)
 802                 return real_size;
 803         if (real_size > size)
 804                 return -ERANGE;
 805
 806         ext_entry = (void *)(ext_acl + 1);
 807         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
 808
 809         for (n=0; n < acl->a_count; n++, ext_entry++) {
 810                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 811                 ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 812                 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
 813                 switch(acl_e->e_tag) {
 814                 case ACL_USER:
 815                         ext_entry->e_id =
 816                                 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
 817                         break;
 818                 case ACL_GROUP:
 819                         ext_entry->e_id =
 820                                 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
 821                         break;
 822                 default:
 823                         ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
 824                         break;
 825                 }
 826         }
 827         return real_size;
 828 }
 829 EXPORT_SYMBOL (posix_acl_to_xattr);
 830
 831 static int
 832 posix_acl_xattr_get(const struct xattr_handler *handler,
 833                     struct dentry *unused, struct inode *inode,
 834                     const char *name, void *value, size_t size)
 835 {
 836         struct posix_acl *acl;
 837         int error;
 838
 839         if (!IS_POSIXACL(inode))
 840                 return -EOPNOTSUPP;
 841         if (S_ISLNK(inode->i_mode))
 842                 return -EOPNOTSUPP;
 843
 844         acl = get_acl(inode, handler->flags);
 845         if (IS_ERR(acl))
 846                 return PTR_ERR(acl);
 847         if (acl == NULL)
 848                 return -ENODATA;
 849
 850         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 851         posix_acl_release(acl);
 852
 853         return error;
 854 }
 855
 856 int
 857 set_posix_acl(struct inode *inode, int type, struct posix_acl *acl)
 858 {
 859         if (!IS_POSIXACL(inode))
 860                 return -EOPNOTSUPP;
 861         if (!inode->i_op->set_acl)
 862                 return -EOPNOTSUPP;
 863
 864         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 865                 return acl ? -EACCES : 0;
 866         if (!inode_owner_or_capable(inode))
 867                 return -EPERM;
 868
 869         if (acl) {
 870                 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
 871                 if (ret)
 872                         return ret;
 873         }
 874         return inode->i_op->set_acl(inode, acl, type);
 875 }
 876 EXPORT_SYMBOL(set_posix_acl);
 877
 878 static int
 879 posix_acl_xattr_set(const struct xattr_handler *handler,
 880                     struct dentry *unused, struct inode *inode,
 881                     const char *name, const void *value,
 882                     size_t size, int flags)
 883 {
 884         struct posix_acl *acl = NULL;
 885         int ret;
 886
 887         if (value) {
 888                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 889                 if (IS_ERR(acl))
 890                         return PTR_ERR(acl);
 891         }
 892         ret = set_posix_acl(inode, handler->flags, acl);
 893         posix_acl_release(acl);
 894         return ret;
 895 }
 896
 897 static bool
 898 posix_acl_xattr_list(struct dentry *dentry)
 899 {
 900         return IS_POSIXACL(d_backing_inode(dentry));
 901 }
 902
 903 const struct xattr_handler posix_acl_access_xattr_handler = {
 904         .name = XATTR_NAME_POSIX_ACL_ACCESS,
 905         .flags = ACL_TYPE_ACCESS,
 906         .list = posix_acl_xattr_list,
 907         .get = posix_acl_xattr_get,
 908         .set = posix_acl_xattr_set,
 909 };
 910 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
 911
 912 const struct xattr_handler posix_acl_default_xattr_handler = {
 913         .name = XATTR_NAME_POSIX_ACL_DEFAULT,
 914         .flags = ACL_TYPE_DEFAULT,
 915         .list = posix_acl_xattr_list,
 916         .get = posix_acl_xattr_get,
 917         .set = posix_acl_xattr_set,
 918 };
 919 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
 920
 921 int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 922 {
 923         int error;
 924
 925         if (type == ACL_TYPE_ACCESS) {
 926                 error = posix_acl_update_mode(inode,
 927                                 &inode->i_mode, &acl);
 928                 if (error)
 929                         return error;
 930         }
 931
 932         inode->i_ctime = current_time(inode);
 933         set_cached_acl(inode, type, acl);
 934         return 0;
 935 }
 936
 937 int simple_acl_create(struct inode *dir, struct inode *inode)
 938 {
 939         struct posix_acl *default_acl, *acl;
 940         int error;
 941
 942         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 943         if (error)
 944                 return error;
 945
 946         set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
 947         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 948
 949         if (default_acl)
 950                 posix_acl_release(default_acl);
 951         if (acl)
 952                 posix_acl_release(acl);
 953         return 0;
 954 }