fs/posix_acl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org>
   4  *
   5  * Fixes from William Schumacher incorporated on 15 March 2001.
   6  *    (Reported by Charles Bertsch, <CBertsch@microtest.com>).
   7  */
   8
   9 /*
  10  *  This file contains generic functions for manipulating
  11  *  POSIX 1003.1e draft standard 17 ACLs.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/slab.h>
  16 #include <linux/atomic.h>
  17 #include <linux/fs.h>
  18 #include <linux/sched.h>
  19 #include <linux/cred.h>
  20 #include <linux/posix_acl.h>
  21 #include <linux/posix_acl_xattr.h>
  22 #include <linux/xattr.h>
  23 #include <linux/export.h>
  24 #include <linux/user_namespace.h>
  25 #include <linux/namei.h>
  26 #include <linux/mnt_idmapping.h>
  27
  28 static struct posix_acl **acl_by_type(struct inode *inode, int type)
  29 {
  30         switch (type) {
  31         case ACL_TYPE_ACCESS:
  32                 return &inode->i_acl;
  33         case ACL_TYPE_DEFAULT:
  34                 return &inode->i_default_acl;
  35         default:
  36                 BUG();
  37         }
  38 }
  39
  40 struct posix_acl *get_cached_acl(struct inode *inode, int type)
  41 {
  42         struct posix_acl **p = acl_by_type(inode, type);
  43         struct posix_acl *acl;
  44
  45         for (;;) {
  46                 rcu_read_lock();
  47                 acl = rcu_dereference(*p);
  48                 if (!acl || is_uncached_acl(acl) ||
  49                     refcount_inc_not_zero(&acl->a_refcount))
  50                         break;
  51                 rcu_read_unlock();
  52                 cpu_relax();
  53         }
  54         rcu_read_unlock();
  55         return acl;
  56 }
  57 EXPORT_SYMBOL(get_cached_acl);
  58
  59 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
  60 {
  61         struct posix_acl *acl = rcu_dereference(*acl_by_type(inode, type));
  62
  63         if (acl == ACL_DONT_CACHE) {
  64                 struct posix_acl *ret;
  65
  66                 ret = inode->i_op->get_acl(inode, type, LOOKUP_RCU);
  67                 if (!IS_ERR(ret))
  68                         acl = ret;
  69         }
  70
  71         return acl;
  72 }
  73 EXPORT_SYMBOL(get_cached_acl_rcu);
  74
  75 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
  76 {
  77         struct posix_acl **p = acl_by_type(inode, type);
  78         struct posix_acl *old;
  79
  80         old = xchg(p, posix_acl_dup(acl));
  81         if (!is_uncached_acl(old))
  82                 posix_acl_release(old);
  83 }
  84 EXPORT_SYMBOL(set_cached_acl);
  85
  86 static void __forget_cached_acl(struct posix_acl **p)
  87 {
  88         struct posix_acl *old;
  89
  90         old = xchg(p, ACL_NOT_CACHED);
  91         if (!is_uncached_acl(old))
  92                 posix_acl_release(old);
  93 }
  94
  95 void forget_cached_acl(struct inode *inode, int type)
  96 {
  97         __forget_cached_acl(acl_by_type(inode, type));
  98 }
  99 EXPORT_SYMBOL(forget_cached_acl);
 100
 101 void forget_all_cached_acls(struct inode *inode)
 102 {
 103         __forget_cached_acl(&inode->i_acl);
 104         __forget_cached_acl(&inode->i_default_acl);
 105 }
 106 EXPORT_SYMBOL(forget_all_cached_acls);
 107
 108 struct posix_acl *get_acl(struct inode *inode, int type)
 109 {
 110         void *sentinel;
 111         struct posix_acl **p;
 112         struct posix_acl *acl;
 113
 114         /*
 115          * The sentinel is used to detect when another operation like
 116          * set_cached_acl() or forget_cached_acl() races with get_acl().
 117          * It is guaranteed that is_uncached_acl(sentinel) is true.
 118          */
 119
 120         acl = get_cached_acl(inode, type);
 121         if (!is_uncached_acl(acl))
 122                 return acl;
 123
 124         if (!IS_POSIXACL(inode))
 125                 return NULL;
 126
 127         sentinel = uncached_acl_sentinel(current);
 128         p = acl_by_type(inode, type);
 129
 130         /*
 131          * If the ACL isn't being read yet, set our sentinel.  Otherwise, the
 132          * current value of the ACL will not be ACL_NOT_CACHED and so our own
 133          * sentinel will not be set; another task will update the cache.  We
 134          * could wait for that other task to complete its job, but it's easier
 135          * to just call ->get_acl to fetch the ACL ourself.  (This is going to
 136          * be an unlikely race.)
 137          */
 138         cmpxchg(p, ACL_NOT_CACHED, sentinel);
 139
 140         /*
 141          * Normally, the ACL returned by ->get_acl will be cached.
 142          * A filesystem can prevent that by calling
 143          * forget_cached_acl(inode, type) in ->get_acl.
 144          *
 145          * If the filesystem doesn't have a get_acl() function at all, we'll
 146          * just create the negative cache entry.
 147          */
 148         if (!inode->i_op->get_acl) {
 149                 set_cached_acl(inode, type, NULL);
 150                 return NULL;
 151         }
 152         acl = inode->i_op->get_acl(inode, type, false);
 153
 154         if (IS_ERR(acl)) {
 155                 /*
 156                  * Remove our sentinel so that we don't block future attempts
 157                  * to cache the ACL.
 158                  */
 159                 cmpxchg(p, sentinel, ACL_NOT_CACHED);
 160                 return acl;
 161         }
 162
 163         /*
 164          * Cache the result, but only if our sentinel is still in place.
 165          */
 166         posix_acl_dup(acl);
 167         if (unlikely(cmpxchg(p, sentinel, acl) != sentinel))
 168                 posix_acl_release(acl);
 169         return acl;
 170 }
 171 EXPORT_SYMBOL(get_acl);
 172
 173 /*
 174  * Init a fresh posix_acl
 175  */
 176 void
 177 posix_acl_init(struct posix_acl *acl, int count)
 178 {
 179         refcount_set(&acl->a_refcount, 1);
 180         acl->a_count = count;
 181 }
 182 EXPORT_SYMBOL(posix_acl_init);
 183
 184 /*
 185  * Allocate a new ACL with the specified number of entries.
 186  */
 187 struct posix_acl *
 188 posix_acl_alloc(int count, gfp_t flags)
 189 {
 190         const size_t size = sizeof(struct posix_acl) +
 191                             count * sizeof(struct posix_acl_entry);
 192         struct posix_acl *acl = kmalloc(size, flags);
 193         if (acl)
 194                 posix_acl_init(acl, count);
 195         return acl;
 196 }
 197 EXPORT_SYMBOL(posix_acl_alloc);
 198
 199 /*
 200  * Clone an ACL.
 201  */
 202 struct posix_acl *
 203 posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
 204 {
 205         struct posix_acl *clone = NULL;
 206
 207         if (acl) {
 208                 int size = sizeof(struct posix_acl) + acl->a_count *
 209                            sizeof(struct posix_acl_entry);
 210                 clone = kmemdup(acl, size, flags);
 211                 if (clone)
 212                         refcount_set(&clone->a_refcount, 1);
 213         }
 214         return clone;
 215 }
 216 EXPORT_SYMBOL_GPL(posix_acl_clone);
 217
 218 /*
 219  * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
 220  */
 221 int
 222 posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl)
 223 {
 224         const struct posix_acl_entry *pa, *pe;
 225         int state = ACL_USER_OBJ;
 226         int needs_mask = 0;
 227
 228         FOREACH_ACL_ENTRY(pa, acl, pe) {
 229                 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
 230                         return -EINVAL;
 231                 switch (pa->e_tag) {
 232                         case ACL_USER_OBJ:
 233                                 if (state == ACL_USER_OBJ) {
 234                                         state = ACL_USER;
 235                                         break;
 236                                 }
 237                                 return -EINVAL;
 238
 239                         case ACL_USER:
 240                                 if (state != ACL_USER)
 241                                         return -EINVAL;
 242                                 if (!kuid_has_mapping(user_ns, pa->e_uid))
 243                                         return -EINVAL;
 244                                 needs_mask = 1;
 245                                 break;
 246
 247                         case ACL_GROUP_OBJ:
 248                                 if (state == ACL_USER) {
 249                                         state = ACL_GROUP;
 250                                         break;
 251                                 }
 252                                 return -EINVAL;
 253
 254                         case ACL_GROUP:
 255                                 if (state != ACL_GROUP)
 256                                         return -EINVAL;
 257                                 if (!kgid_has_mapping(user_ns, pa->e_gid))
 258                                         return -EINVAL;
 259                                 needs_mask = 1;
 260                                 break;
 261
 262                         case ACL_MASK:
 263                                 if (state != ACL_GROUP)
 264                                         return -EINVAL;
 265                                 state = ACL_OTHER;
 266                                 break;
 267
 268                         case ACL_OTHER:
 269                                 if (state == ACL_OTHER ||
 270                                     (state == ACL_GROUP && !needs_mask)) {
 271                                         state = 0;
 272                                         break;
 273                                 }
 274                                 return -EINVAL;
 275
 276                         default:
 277                                 return -EINVAL;
 278                 }
 279         }
 280         if (state == 0)
 281                 return 0;
 282         return -EINVAL;
 283 }
 284 EXPORT_SYMBOL(posix_acl_valid);
 285
 286 /*
 287  * Returns 0 if the acl can be exactly represented in the traditional
 288  * file mode permission bits, or else 1. Returns -E... on error.
 289  */
 290 int
 291 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
 292 {
 293         const struct posix_acl_entry *pa, *pe;
 294         umode_t mode = 0;
 295         int not_equiv = 0;
 296
 297         /*
 298          * A null ACL can always be presented as mode bits.
 299          */
 300         if (!acl)
 301                 return 0;
 302
 303         FOREACH_ACL_ENTRY(pa, acl, pe) {
 304                 switch (pa->e_tag) {
 305                         case ACL_USER_OBJ:
 306                                 mode |= (pa->e_perm & S_IRWXO) << 6;
 307                                 break;
 308                         case ACL_GROUP_OBJ:
 309                                 mode |= (pa->e_perm & S_IRWXO) << 3;
 310                                 break;
 311                         case ACL_OTHER:
 312                                 mode |= pa->e_perm & S_IRWXO;
 313                                 break;
 314                         case ACL_MASK:
 315                                 mode = (mode & ~S_IRWXG) |
 316                                        ((pa->e_perm & S_IRWXO) << 3);
 317                                 not_equiv = 1;
 318                                 break;
 319                         case ACL_USER:
 320                         case ACL_GROUP:
 321                                 not_equiv = 1;
 322                                 break;
 323                         default:
 324                                 return -EINVAL;
 325                 }
 326         }
 327         if (mode_p)
 328                 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 329         return not_equiv;
 330 }
 331 EXPORT_SYMBOL(posix_acl_equiv_mode);
 332
 333 /*
 334  * Create an ACL representing the file mode permission bits of an inode.
 335  */
 336 struct posix_acl *
 337 posix_acl_from_mode(umode_t mode, gfp_t flags)
 338 {
 339         struct posix_acl *acl = posix_acl_alloc(3, flags);
 340         if (!acl)
 341                 return ERR_PTR(-ENOMEM);
 342
 343         acl->a_entries[0].e_tag  = ACL_USER_OBJ;
 344         acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
 345
 346         acl->a_entries[1].e_tag  = ACL_GROUP_OBJ;
 347         acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
 348
 349         acl->a_entries[2].e_tag  = ACL_OTHER;
 350         acl->a_entries[2].e_perm = (mode & S_IRWXO);
 351         return acl;
 352 }
 353 EXPORT_SYMBOL(posix_acl_from_mode);
 354
 355 /*
 356  * Return 0 if current is granted want access to the inode
 357  * by the acl. Returns -E... otherwise.
 358  */
 359 int
 360 posix_acl_permission(struct user_namespace *mnt_userns, struct inode *inode,
 361                      const struct posix_acl *acl, int want)
 362 {
 363         const struct posix_acl_entry *pa, *pe, *mask_obj;
 364         struct user_namespace *fs_userns = i_user_ns(inode);
 365         int found = 0;
 366         vfsuid_t vfsuid;
 367         vfsgid_t vfsgid;
 368
 369         want &= MAY_READ | MAY_WRITE | MAY_EXEC;
 370
 371         FOREACH_ACL_ENTRY(pa, acl, pe) {
 372                 switch(pa->e_tag) {
 373                         case ACL_USER_OBJ:
 374                                 /* (May have been checked already) */
 375                                 vfsuid = i_uid_into_vfsuid(mnt_userns, inode);
 376                                 if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
 377                                         goto check_perm;
 378                                 break;
 379                         case ACL_USER:
 380                                 vfsuid = make_vfsuid(mnt_userns, fs_userns,
 381                                                      pa->e_uid);
 382                                 if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
 383                                         goto mask;
 384                                 break;
 385                         case ACL_GROUP_OBJ:
 386                                 vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
 387                                 if (vfsgid_in_group_p(vfsgid)) {
 388                                         found = 1;
 389                                         if ((pa->e_perm & want) == want)
 390                                                 goto mask;
 391                                 }
 392                                 break;
 393                         case ACL_GROUP:
 394                                 vfsgid = make_vfsgid(mnt_userns, fs_userns,
 395                                                      pa->e_gid);
 396                                 if (vfsgid_in_group_p(vfsgid)) {
 397                                         found = 1;
 398                                         if ((pa->e_perm & want) == want)
 399                                                 goto mask;
 400                                 }
 401                                 break;
 402                         case ACL_MASK:
 403                                 break;
 404                         case ACL_OTHER:
 405                                 if (found)
 406                                         return -EACCES;
 407                                 else
 408                                         goto check_perm;
 409                         default:
 410                                 return -EIO;
 411                 }
 412         }
 413         return -EIO;
 414
 415 mask:
 416         for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
 417                 if (mask_obj->e_tag == ACL_MASK) {
 418                         if ((pa->e_perm & mask_obj->e_perm & want) == want)
 419                                 return 0;
 420                         return -EACCES;
 421                 }
 422         }
 423
 424 check_perm:
 425         if ((pa->e_perm & want) == want)
 426                 return 0;
 427         return -EACCES;
 428 }
 429
 430 /*
 431  * Modify acl when creating a new inode. The caller must ensure the acl is
 432  * only referenced once.
 433  *
 434  * mode_p initially must contain the mode parameter to the open() / creat()
 435  * system calls. All permissions that are not granted by the acl are removed.
 436  * The permissions in the acl are changed to reflect the mode_p parameter.
 437  */
 438 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
 439 {
 440         struct posix_acl_entry *pa, *pe;
 441         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 442         umode_t mode = *mode_p;
 443         int not_equiv = 0;
 444
 445         /* assert(atomic_read(acl->a_refcount) == 1); */
 446
 447         FOREACH_ACL_ENTRY(pa, acl, pe) {
 448                 switch(pa->e_tag) {
 449                         case ACL_USER_OBJ:
 450                                 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
 451                                 mode &= (pa->e_perm << 6) | ~S_IRWXU;
 452                                 break;
 453
 454                         case ACL_USER:
 455                         case ACL_GROUP:
 456                                 not_equiv = 1;
 457                                 break;
 458
 459                         case ACL_GROUP_OBJ:
 460                                 group_obj = pa;
 461                                 break;
 462
 463                         case ACL_OTHER:
 464                                 pa->e_perm &= mode | ~S_IRWXO;
 465                                 mode &= pa->e_perm | ~S_IRWXO;
 466                                 break;
 467
 468                         case ACL_MASK:
 469                                 mask_obj = pa;
 470                                 not_equiv = 1;
 471                                 break;
 472
 473                         default:
 474                                 return -EIO;
 475                 }
 476         }
 477
 478         if (mask_obj) {
 479                 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 480                 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
 481         } else {
 482                 if (!group_obj)
 483                         return -EIO;
 484                 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 485                 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
 486         }
 487
 488         *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 489         return not_equiv;
 490 }
 491
 492 /*
 493  * Modify the ACL for the chmod syscall.
 494  */
 495 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
 496 {
 497         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 498         struct posix_acl_entry *pa, *pe;
 499
 500         /* assert(atomic_read(acl->a_refcount) == 1); */
 501
 502         FOREACH_ACL_ENTRY(pa, acl, pe) {
 503                 switch(pa->e_tag) {
 504                         case ACL_USER_OBJ:
 505                                 pa->e_perm = (mode & S_IRWXU) >> 6;
 506                                 break;
 507
 508                         case ACL_USER:
 509                         case ACL_GROUP:
 510                                 break;
 511
 512                         case ACL_GROUP_OBJ:
 513                                 group_obj = pa;
 514                                 break;
 515
 516                         case ACL_MASK:
 517                                 mask_obj = pa;
 518                                 break;
 519
 520                         case ACL_OTHER:
 521                                 pa->e_perm = (mode & S_IRWXO);
 522                                 break;
 523
 524                         default:
 525                                 return -EIO;
 526                 }
 527         }
 528
 529         if (mask_obj) {
 530                 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
 531         } else {
 532                 if (!group_obj)
 533                         return -EIO;
 534                 group_obj->e_perm = (mode & S_IRWXG) >> 3;
 535         }
 536
 537         return 0;
 538 }
 539
 540 int
 541 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
 542 {
 543         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 544         int err = -ENOMEM;
 545         if (clone) {
 546                 err = posix_acl_create_masq(clone, mode_p);
 547                 if (err < 0) {
 548                         posix_acl_release(clone);
 549                         clone = NULL;
 550                 }
 551         }
 552         posix_acl_release(*acl);
 553         *acl = clone;
 554         return err;
 555 }
 556 EXPORT_SYMBOL(__posix_acl_create);
 557
 558 int
 559 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
 560 {
 561         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 562         int err = -ENOMEM;
 563         if (clone) {
 564                 err = __posix_acl_chmod_masq(clone, mode);
 565                 if (err) {
 566                         posix_acl_release(clone);
 567                         clone = NULL;
 568                 }
 569         }
 570         posix_acl_release(*acl);
 571         *acl = clone;
 572         return err;
 573 }
 574 EXPORT_SYMBOL(__posix_acl_chmod);
 575
 576 /**
 577  * posix_acl_chmod - chmod a posix acl
 578  *
 579  * @mnt_userns: user namespace of the mount @inode was found from
 580  * @inode:      inode to check permissions on
 581  * @mode:       the new mode of @inode
 582  *
 583  * If the inode has been found through an idmapped mount the user namespace of
 584  * the vfsmount must be passed through @mnt_userns. This function will then
 585  * take care to map the inode according to @mnt_userns before checking
 586  * permissions. On non-idmapped mounts or if permission checking is to be
 587  * performed on the raw inode simply passs init_user_ns.
 588  */
 589 int
 590  posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode,
 591                     umode_t mode)
 592 {
 593         struct posix_acl *acl;
 594         int ret = 0;
 595
 596         if (!IS_POSIXACL(inode))
 597                 return 0;
 598         if (!inode->i_op->set_acl)
 599                 return -EOPNOTSUPP;
 600
 601         acl = get_acl(inode, ACL_TYPE_ACCESS);
 602         if (IS_ERR_OR_NULL(acl)) {
 603                 if (acl == ERR_PTR(-EOPNOTSUPP))
 604                         return 0;
 605                 return PTR_ERR(acl);
 606         }
 607
 608         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 609         if (ret)
 610                 return ret;
 611         ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS);
 612         posix_acl_release(acl);
 613         return ret;
 614 }
 615 EXPORT_SYMBOL(posix_acl_chmod);
 616
 617 int
 618 posix_acl_create(struct inode *dir, umode_t *mode,
 619                 struct posix_acl **default_acl, struct posix_acl **acl)
 620 {
 621         struct posix_acl *p;
 622         struct posix_acl *clone;
 623         int ret;
 624
 625         *acl = NULL;
 626         *default_acl = NULL;
 627
 628         if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
 629                 return 0;
 630
 631         p = get_acl(dir, ACL_TYPE_DEFAULT);
 632         if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
 633                 *mode &= ~current_umask();
 634                 return 0;
 635         }
 636         if (IS_ERR(p))
 637                 return PTR_ERR(p);
 638
 639         ret = -ENOMEM;
 640         clone = posix_acl_clone(p, GFP_NOFS);
 641         if (!clone)
 642                 goto err_release;
 643
 644         ret = posix_acl_create_masq(clone, mode);
 645         if (ret < 0)
 646                 goto err_release_clone;
 647
 648         if (ret == 0)
 649                 posix_acl_release(clone);
 650         else
 651                 *acl = clone;
 652
 653         if (!S_ISDIR(*mode))
 654                 posix_acl_release(p);
 655         else
 656                 *default_acl = p;
 657
 658         return 0;
 659
 660 err_release_clone:
 661         posix_acl_release(clone);
 662 err_release:
 663         posix_acl_release(p);
 664         return ret;
 665 }
 666 EXPORT_SYMBOL_GPL(posix_acl_create);
 667
 668 /**
 669  * posix_acl_update_mode  -  update mode in set_acl
 670  * @mnt_userns: user namespace of the mount @inode was found from
 671  * @inode:      target inode
 672  * @mode_p:     mode (pointer) for update
 673  * @acl:        acl pointer
 674  *
 675  * Update the file mode when setting an ACL: compute the new file permission
 676  * bits based on the ACL.  In addition, if the ACL is equivalent to the new
 677  * file mode, set *@acl to NULL to indicate that no ACL should be set.
 678  *
 679  * As with chmod, clear the setgid bit if the caller is not in the owning group
 680  * or capable of CAP_FSETID (see inode_change_ok).
 681  *
 682  * If the inode has been found through an idmapped mount the user namespace of
 683  * the vfsmount must be passed through @mnt_userns. This function will then
 684  * take care to map the inode according to @mnt_userns before checking
 685  * permissions. On non-idmapped mounts or if permission checking is to be
 686  * performed on the raw inode simply passs init_user_ns.
 687  *
 688  * Called from set_acl inode operations.
 689  */
 690 int posix_acl_update_mode(struct user_namespace *mnt_userns,
 691                           struct inode *inode, umode_t *mode_p,
 692                           struct posix_acl **acl)
 693 {
 694         umode_t mode = inode->i_mode;
 695         int error;
 696
 697         error = posix_acl_equiv_mode(*acl, &mode);
 698         if (error < 0)
 699                 return error;
 700         if (error == 0)
 701                 *acl = NULL;
 702         if (!vfsgid_in_group_p(i_gid_into_vfsgid(mnt_userns, inode)) &&
 703             !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
 704                 mode &= ~S_ISGID;
 705         *mode_p = mode;
 706         return 0;
 707 }
 708 EXPORT_SYMBOL(posix_acl_update_mode);
 709
 710 /*
 711  * Fix up the uids and gids in posix acl extended attributes in place.
 712  */
 713 static int posix_acl_fix_xattr_common(void *value, size_t size)
 714 {
 715         struct posix_acl_xattr_header *header = value;
 716         int count;
 717
 718         if (!header)
 719                 return -EINVAL;
 720         if (size < sizeof(struct posix_acl_xattr_header))
 721                 return -EINVAL;
 722         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 723                 return -EINVAL;
 724
 725         count = posix_acl_xattr_count(size);
 726         if (count < 0)
 727                 return -EINVAL;
 728         if (count == 0)
 729                 return -EINVAL;
 730
 731         return count;
 732 }
 733
 734 void posix_acl_getxattr_idmapped_mnt(struct user_namespace *mnt_userns,
 735                                      const struct inode *inode,
 736                                      void *value, size_t size)
 737 {
 738         struct posix_acl_xattr_header *header = value;
 739         struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
 740         struct user_namespace *fs_userns = i_user_ns(inode);
 741         int count;
 742         vfsuid_t vfsuid;
 743         vfsgid_t vfsgid;
 744         kuid_t uid;
 745         kgid_t gid;
 746
 747         if (no_idmapping(mnt_userns, i_user_ns(inode)))
 748                 return;
 749
 750         count = posix_acl_fix_xattr_common(value, size);
 751         if (count < 0)
 752                 return;
 753
 754         for (end = entry + count; entry != end; entry++) {
 755                 switch (le16_to_cpu(entry->e_tag)) {
 756                 case ACL_USER:
 757                         uid = make_kuid(&init_user_ns, le32_to_cpu(entry->e_id));
 758                         vfsuid = make_vfsuid(mnt_userns, fs_userns, uid);
 759                         entry->e_id = cpu_to_le32(from_kuid(&init_user_ns,
 760                                                 vfsuid_into_kuid(vfsuid)));
 761                         break;
 762                 case ACL_GROUP:
 763                         gid = make_kgid(&init_user_ns, le32_to_cpu(entry->e_id));
 764                         vfsgid = make_vfsgid(mnt_userns, fs_userns, gid);
 765                         entry->e_id = cpu_to_le32(from_kgid(&init_user_ns,
 766                                                 vfsgid_into_kgid(vfsgid)));
 767                         break;
 768                 default:
 769                         break;
 770                 }
 771         }
 772 }
 773
 774 void posix_acl_setxattr_idmapped_mnt(struct user_namespace *mnt_userns,
 775                                      const struct inode *inode,
 776                                      void *value, size_t size)
 777 {
 778         struct posix_acl_xattr_header *header = value;
 779         struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
 780         struct user_namespace *fs_userns = i_user_ns(inode);
 781         int count;
 782         vfsuid_t vfsuid;
 783         vfsgid_t vfsgid;
 784         kuid_t uid;
 785         kgid_t gid;
 786
 787         if (no_idmapping(mnt_userns, i_user_ns(inode)))
 788                 return;
 789
 790         count = posix_acl_fix_xattr_common(value, size);
 791         if (count < 0)
 792                 return;
 793
 794         for (end = entry + count; entry != end; entry++) {
 795                 switch (le16_to_cpu(entry->e_tag)) {
 796                 case ACL_USER:
 797                         uid = make_kuid(&init_user_ns, le32_to_cpu(entry->e_id));
 798                         vfsuid = VFSUIDT_INIT(uid);
 799                         uid = from_vfsuid(mnt_userns, fs_userns, vfsuid);
 800                         entry->e_id = cpu_to_le32(from_kuid(&init_user_ns, uid));
 801                         break;
 802                 case ACL_GROUP:
 803                         gid = make_kgid(&init_user_ns, le32_to_cpu(entry->e_id));
 804                         vfsgid = VFSGIDT_INIT(gid);
 805                         gid = from_vfsgid(mnt_userns, fs_userns, vfsgid);
 806                         entry->e_id = cpu_to_le32(from_kgid(&init_user_ns, gid));
 807                         break;
 808                 default:
 809                         break;
 810                 }
 811         }
 812 }
 813
 814 static void posix_acl_fix_xattr_userns(
 815         struct user_namespace *to, struct user_namespace *from,
 816         void *value, size_t size)
 817 {
 818         struct posix_acl_xattr_header *header = value;
 819         struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
 820         int count;
 821         kuid_t uid;
 822         kgid_t gid;
 823
 824         count = posix_acl_fix_xattr_common(value, size);
 825         if (count < 0)
 826                 return;
 827
 828         for (end = entry + count; entry != end; entry++) {
 829                 switch(le16_to_cpu(entry->e_tag)) {
 830                 case ACL_USER:
 831                         uid = make_kuid(from, le32_to_cpu(entry->e_id));
 832                         entry->e_id = cpu_to_le32(from_kuid(to, uid));
 833                         break;
 834                 case ACL_GROUP:
 835                         gid = make_kgid(from, le32_to_cpu(entry->e_id));
 836                         entry->e_id = cpu_to_le32(from_kgid(to, gid));
 837                         break;
 838                 default:
 839                         break;
 840                 }
 841         }
 842 }
 843
 844 void posix_acl_fix_xattr_from_user(void *value, size_t size)
 845 {
 846         struct user_namespace *user_ns = current_user_ns();
 847         if (user_ns == &init_user_ns)
 848                 return;
 849         posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
 850 }
 851
 852 void posix_acl_fix_xattr_to_user(void *value, size_t size)
 853 {
 854         struct user_namespace *user_ns = current_user_ns();
 855         if (user_ns == &init_user_ns)
 856                 return;
 857         posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
 858 }
 859
 860 /*
 861  * Convert from extended attribute to in-memory representation.
 862  */
 863 struct posix_acl *
 864 posix_acl_from_xattr(struct user_namespace *user_ns,
 865                      const void *value, size_t size)
 866 {
 867         const struct posix_acl_xattr_header *header = value;
 868         const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
 869         int count;
 870         struct posix_acl *acl;
 871         struct posix_acl_entry *acl_e;
 872
 873         if (!value)
 874                 return NULL;
 875         if (size < sizeof(struct posix_acl_xattr_header))
 876                  return ERR_PTR(-EINVAL);
 877         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 878                 return ERR_PTR(-EOPNOTSUPP);
 879
 880         count = posix_acl_xattr_count(size);
 881         if (count < 0)
 882                 return ERR_PTR(-EINVAL);
 883         if (count == 0)
 884                 return NULL;
 885
 886         acl = posix_acl_alloc(count, GFP_NOFS);
 887         if (!acl)
 888                 return ERR_PTR(-ENOMEM);
 889         acl_e = acl->a_entries;
 890
 891         for (end = entry + count; entry != end; acl_e++, entry++) {
 892                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
 893                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
 894
 895                 switch(acl_e->e_tag) {
 896                         case ACL_USER_OBJ:
 897                         case ACL_GROUP_OBJ:
 898                         case ACL_MASK:
 899                         case ACL_OTHER:
 900                                 break;
 901
 902                         case ACL_USER:
 903                                 acl_e->e_uid =
 904                                         make_kuid(user_ns,
 905                                                   le32_to_cpu(entry->e_id));
 906                                 if (!uid_valid(acl_e->e_uid))
 907                                         goto fail;
 908                                 break;
 909                         case ACL_GROUP:
 910                                 acl_e->e_gid =
 911                                         make_kgid(user_ns,
 912                                                   le32_to_cpu(entry->e_id));
 913                                 if (!gid_valid(acl_e->e_gid))
 914                                         goto fail;
 915                                 break;
 916
 917                         default:
 918                                 goto fail;
 919                 }
 920         }
 921         return acl;
 922
 923 fail:
 924         posix_acl_release(acl);
 925         return ERR_PTR(-EINVAL);
 926 }
 927 EXPORT_SYMBOL (posix_acl_from_xattr);
 928
 929 /*
 930  * Convert from in-memory to extended attribute representation.
 931  */
 932 int
 933 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
 934                    void *buffer, size_t size)
 935 {
 936         struct posix_acl_xattr_header *ext_acl = buffer;
 937         struct posix_acl_xattr_entry *ext_entry;
 938         int real_size, n;
 939
 940         real_size = posix_acl_xattr_size(acl->a_count);
 941         if (!buffer)
 942                 return real_size;
 943         if (real_size > size)
 944                 return -ERANGE;
 945
 946         ext_entry = (void *)(ext_acl + 1);
 947         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
 948
 949         for (n=0; n < acl->a_count; n++, ext_entry++) {
 950                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 951                 ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 952                 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
 953                 switch(acl_e->e_tag) {
 954                 case ACL_USER:
 955                         ext_entry->e_id =
 956                                 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
 957                         break;
 958                 case ACL_GROUP:
 959                         ext_entry->e_id =
 960                                 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
 961                         break;
 962                 default:
 963                         ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
 964                         break;
 965                 }
 966         }
 967         return real_size;
 968 }
 969 EXPORT_SYMBOL (posix_acl_to_xattr);
 970
 971 static int
 972 posix_acl_xattr_get(const struct xattr_handler *handler,
 973                     struct dentry *unused, struct inode *inode,
 974                     const char *name, void *value, size_t size)
 975 {
 976         struct posix_acl *acl;
 977         int error;
 978
 979         if (!IS_POSIXACL(inode))
 980                 return -EOPNOTSUPP;
 981         if (S_ISLNK(inode->i_mode))
 982                 return -EOPNOTSUPP;
 983
 984         acl = get_acl(inode, handler->flags);
 985         if (IS_ERR(acl))
 986                 return PTR_ERR(acl);
 987         if (acl == NULL)
 988                 return -ENODATA;
 989
 990         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 991         posix_acl_release(acl);
 992
 993         return error;
 994 }
 995
 996 int
 997 set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode,
 998               int type, struct posix_acl *acl)
 999 {
1000         if (!IS_POSIXACL(inode))
1001                 return -EOPNOTSUPP;
1002         if (!inode->i_op->set_acl)
1003                 return -EOPNOTSUPP;
1004
1005         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
1006                 return acl ? -EACCES : 0;
1007         if (!inode_owner_or_capable(mnt_userns, inode))
1008                 return -EPERM;
1009
1010         if (acl) {
1011                 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
1012                 if (ret)
1013                         return ret;
1014         }
1015         return inode->i_op->set_acl(mnt_userns, inode, acl, type);
1016 }
1017 EXPORT_SYMBOL(set_posix_acl);
1018
1019 static int
1020 posix_acl_xattr_set(const struct xattr_handler *handler,
1021                            struct user_namespace *mnt_userns,
1022                            struct dentry *unused, struct inode *inode,
1023                            const char *name, const void *value, size_t size,
1024                            int flags)
1025 {
1026         struct posix_acl *acl = NULL;
1027         int ret;
1028
1029         if (value) {
1030                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
1031                 if (IS_ERR(acl))
1032                         return PTR_ERR(acl);
1033         }
1034         ret = set_posix_acl(mnt_userns, inode, handler->flags, acl);
1035         posix_acl_release(acl);
1036         return ret;
1037 }
1038
1039 static bool
1040 posix_acl_xattr_list(struct dentry *dentry)
1041 {
1042         return IS_POSIXACL(d_backing_inode(dentry));
1043 }
1044
1045 const struct xattr_handler posix_acl_access_xattr_handler = {
1046         .name = XATTR_NAME_POSIX_ACL_ACCESS,
1047         .flags = ACL_TYPE_ACCESS,
1048         .list = posix_acl_xattr_list,
1049         .get = posix_acl_xattr_get,
1050         .set = posix_acl_xattr_set,
1051 };
1052 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
1053
1054 const struct xattr_handler posix_acl_default_xattr_handler = {
1055         .name = XATTR_NAME_POSIX_ACL_DEFAULT,
1056         .flags = ACL_TYPE_DEFAULT,
1057         .list = posix_acl_xattr_list,
1058         .get = posix_acl_xattr_get,
1059         .set = posix_acl_xattr_set,
1060 };
1061 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
1062
1063 int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
1064                    struct posix_acl *acl, int type)
1065 {
1066         int error;
1067
1068         if (type == ACL_TYPE_ACCESS) {
1069                 error = posix_acl_update_mode(mnt_userns, inode,
1070                                 &inode->i_mode, &acl);
1071                 if (error)
1072                         return error;
1073         }
1074
1075         inode->i_ctime = current_time(inode);
1076         set_cached_acl(inode, type, acl);
1077         return 0;
1078 }
1079
1080 int simple_acl_create(struct inode *dir, struct inode *inode)
1081 {
1082         struct posix_acl *default_acl, *acl;
1083         int error;
1084
1085         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
1086         if (error)
1087                 return error;
1088
1089         set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
1090         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
1091
1092         if (default_acl)
1093                 posix_acl_release(default_acl);
1094         if (acl)
1095                 posix_acl_release(acl);
1096         return 0;
1097 }