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         int found = 0;
 365         vfsuid_t vfsuid;
 366         vfsgid_t vfsgid;
 367
 368         want &= MAY_READ | MAY_WRITE | MAY_EXEC;
 369
 370         FOREACH_ACL_ENTRY(pa, acl, pe) {
 371                 switch(pa->e_tag) {
 372                         case ACL_USER_OBJ:
 373                                 /* (May have been checked already) */
 374                                 vfsuid = i_uid_into_vfsuid(mnt_userns, inode);
 375                                 if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
 376                                         goto check_perm;
 377                                 break;
 378                         case ACL_USER:
 379                                 vfsuid = make_vfsuid(mnt_userns, &init_user_ns,
 380                                                      pa->e_uid);
 381                                 if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
 382                                         goto mask;
 383                                 break;
 384                         case ACL_GROUP_OBJ:
 385                                 vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
 386                                 if (vfsgid_in_group_p(vfsgid)) {
 387                                         found = 1;
 388                                         if ((pa->e_perm & want) == want)
 389                                                 goto mask;
 390                                 }
 391                                 break;
 392                         case ACL_GROUP:
 393                                 vfsgid = make_vfsgid(mnt_userns, &init_user_ns,
 394                                                      pa->e_gid);
 395                                 if (vfsgid_in_group_p(vfsgid)) {
 396                                         found = 1;
 397                                         if ((pa->e_perm & want) == want)
 398                                                 goto mask;
 399                                 }
 400                                 break;
 401                         case ACL_MASK:
 402                                 break;
 403                         case ACL_OTHER:
 404                                 if (found)
 405                                         return -EACCES;
 406                                 else
 407                                         goto check_perm;
 408                         default:
 409                                 return -EIO;
 410                 }
 411         }
 412         return -EIO;
 413
 414 mask:
 415         for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
 416                 if (mask_obj->e_tag == ACL_MASK) {
 417                         if ((pa->e_perm & mask_obj->e_perm & want) == want)
 418                                 return 0;
 419                         return -EACCES;
 420                 }
 421         }
 422
 423 check_perm:
 424         if ((pa->e_perm & want) == want)
 425                 return 0;
 426         return -EACCES;
 427 }
 428
 429 /*
 430  * Modify acl when creating a new inode. The caller must ensure the acl is
 431  * only referenced once.
 432  *
 433  * mode_p initially must contain the mode parameter to the open() / creat()
 434  * system calls. All permissions that are not granted by the acl are removed.
 435  * The permissions in the acl are changed to reflect the mode_p parameter.
 436  */
 437 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
 438 {
 439         struct posix_acl_entry *pa, *pe;
 440         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 441         umode_t mode = *mode_p;
 442         int not_equiv = 0;
 443
 444         /* assert(atomic_read(acl->a_refcount) == 1); */
 445
 446         FOREACH_ACL_ENTRY(pa, acl, pe) {
 447                 switch(pa->e_tag) {
 448                         case ACL_USER_OBJ:
 449                                 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
 450                                 mode &= (pa->e_perm << 6) | ~S_IRWXU;
 451                                 break;
 452
 453                         case ACL_USER:
 454                         case ACL_GROUP:
 455                                 not_equiv = 1;
 456                                 break;
 457
 458                         case ACL_GROUP_OBJ:
 459                                 group_obj = pa;
 460                                 break;
 461
 462                         case ACL_OTHER:
 463                                 pa->e_perm &= mode | ~S_IRWXO;
 464                                 mode &= pa->e_perm | ~S_IRWXO;
 465                                 break;
 466
 467                         case ACL_MASK:
 468                                 mask_obj = pa;
 469                                 not_equiv = 1;
 470                                 break;
 471
 472                         default:
 473                                 return -EIO;
 474                 }
 475         }
 476
 477         if (mask_obj) {
 478                 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 479                 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
 480         } else {
 481                 if (!group_obj)
 482                         return -EIO;
 483                 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 484                 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
 485         }
 486
 487         *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 488         return not_equiv;
 489 }
 490
 491 /*
 492  * Modify the ACL for the chmod syscall.
 493  */
 494 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
 495 {
 496         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 497         struct posix_acl_entry *pa, *pe;
 498
 499         /* assert(atomic_read(acl->a_refcount) == 1); */
 500
 501         FOREACH_ACL_ENTRY(pa, acl, pe) {
 502                 switch(pa->e_tag) {
 503                         case ACL_USER_OBJ:
 504                                 pa->e_perm = (mode & S_IRWXU) >> 6;
 505                                 break;
 506
 507                         case ACL_USER:
 508                         case ACL_GROUP:
 509                                 break;
 510
 511                         case ACL_GROUP_OBJ:
 512                                 group_obj = pa;
 513                                 break;
 514
 515                         case ACL_MASK:
 516                                 mask_obj = pa;
 517                                 break;
 518
 519                         case ACL_OTHER:
 520                                 pa->e_perm = (mode & S_IRWXO);
 521                                 break;
 522
 523                         default:
 524                                 return -EIO;
 525                 }
 526         }
 527
 528         if (mask_obj) {
 529                 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
 530         } else {
 531                 if (!group_obj)
 532                         return -EIO;
 533                 group_obj->e_perm = (mode & S_IRWXG) >> 3;
 534         }
 535
 536         return 0;
 537 }
 538
 539 int
 540 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
 541 {
 542         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 543         int err = -ENOMEM;
 544         if (clone) {
 545                 err = posix_acl_create_masq(clone, mode_p);
 546                 if (err < 0) {
 547                         posix_acl_release(clone);
 548                         clone = NULL;
 549                 }
 550         }
 551         posix_acl_release(*acl);
 552         *acl = clone;
 553         return err;
 554 }
 555 EXPORT_SYMBOL(__posix_acl_create);
 556
 557 int
 558 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
 559 {
 560         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 561         int err = -ENOMEM;
 562         if (clone) {
 563                 err = __posix_acl_chmod_masq(clone, mode);
 564                 if (err) {
 565                         posix_acl_release(clone);
 566                         clone = NULL;
 567                 }
 568         }
 569         posix_acl_release(*acl);
 570         *acl = clone;
 571         return err;
 572 }
 573 EXPORT_SYMBOL(__posix_acl_chmod);
 574
 575 /**
 576  * posix_acl_chmod - chmod a posix acl
 577  *
 578  * @mnt_userns: user namespace of the mount @inode was found from
 579  * @inode:      inode to check permissions on
 580  * @mode:       the new mode of @inode
 581  *
 582  * If the inode has been found through an idmapped mount the user namespace of
 583  * the vfsmount must be passed through @mnt_userns. This function will then
 584  * take care to map the inode according to @mnt_userns before checking
 585  * permissions. On non-idmapped mounts or if permission checking is to be
 586  * performed on the raw inode simply passs init_user_ns.
 587  */
 588 int
 589  posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode,
 590                     umode_t mode)
 591 {
 592         struct posix_acl *acl;
 593         int ret = 0;
 594
 595         if (!IS_POSIXACL(inode))
 596                 return 0;
 597         if (!inode->i_op->set_acl)
 598                 return -EOPNOTSUPP;
 599
 600         acl = get_acl(inode, ACL_TYPE_ACCESS);
 601         if (IS_ERR_OR_NULL(acl)) {
 602                 if (acl == ERR_PTR(-EOPNOTSUPP))
 603                         return 0;
 604                 return PTR_ERR(acl);
 605         }
 606
 607         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 608         if (ret)
 609                 return ret;
 610         ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS);
 611         posix_acl_release(acl);
 612         return ret;
 613 }
 614 EXPORT_SYMBOL(posix_acl_chmod);
 615
 616 int
 617 posix_acl_create(struct inode *dir, umode_t *mode,
 618                 struct posix_acl **default_acl, struct posix_acl **acl)
 619 {
 620         struct posix_acl *p;
 621         struct posix_acl *clone;
 622         int ret;
 623
 624         *acl = NULL;
 625         *default_acl = NULL;
 626
 627         if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
 628                 return 0;
 629
 630         p = get_acl(dir, ACL_TYPE_DEFAULT);
 631         if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
 632                 *mode &= ~current_umask();
 633                 return 0;
 634         }
 635         if (IS_ERR(p))
 636                 return PTR_ERR(p);
 637
 638         ret = -ENOMEM;
 639         clone = posix_acl_clone(p, GFP_NOFS);
 640         if (!clone)
 641                 goto err_release;
 642
 643         ret = posix_acl_create_masq(clone, mode);
 644         if (ret < 0)
 645                 goto err_release_clone;
 646
 647         if (ret == 0)
 648                 posix_acl_release(clone);
 649         else
 650                 *acl = clone;
 651
 652         if (!S_ISDIR(*mode))
 653                 posix_acl_release(p);
 654         else
 655                 *default_acl = p;
 656
 657         return 0;
 658
 659 err_release_clone:
 660         posix_acl_release(clone);
 661 err_release:
 662         posix_acl_release(p);
 663         return ret;
 664 }
 665 EXPORT_SYMBOL_GPL(posix_acl_create);
 666
 667 /**
 668  * posix_acl_update_mode  -  update mode in set_acl
 669  * @mnt_userns: user namespace of the mount @inode was found from
 670  * @inode:      target inode
 671  * @mode_p:     mode (pointer) for update
 672  * @acl:        acl pointer
 673  *
 674  * Update the file mode when setting an ACL: compute the new file permission
 675  * bits based on the ACL.  In addition, if the ACL is equivalent to the new
 676  * file mode, set *@acl to NULL to indicate that no ACL should be set.
 677  *
 678  * As with chmod, clear the setgid bit if the caller is not in the owning group
 679  * or capable of CAP_FSETID (see inode_change_ok).
 680  *
 681  * If the inode has been found through an idmapped mount the user namespace of
 682  * the vfsmount must be passed through @mnt_userns. This function will then
 683  * take care to map the inode according to @mnt_userns before checking
 684  * permissions. On non-idmapped mounts or if permission checking is to be
 685  * performed on the raw inode simply passs init_user_ns.
 686  *
 687  * Called from set_acl inode operations.
 688  */
 689 int posix_acl_update_mode(struct user_namespace *mnt_userns,
 690                           struct inode *inode, umode_t *mode_p,
 691                           struct posix_acl **acl)
 692 {
 693         umode_t mode = inode->i_mode;
 694         int error;
 695
 696         error = posix_acl_equiv_mode(*acl, &mode);
 697         if (error < 0)
 698                 return error;
 699         if (error == 0)
 700                 *acl = NULL;
 701         if (!vfsgid_in_group_p(i_gid_into_vfsgid(mnt_userns, inode)) &&
 702             !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
 703                 mode &= ~S_ISGID;
 704         *mode_p = mode;
 705         return 0;
 706 }
 707 EXPORT_SYMBOL(posix_acl_update_mode);
 708
 709 /*
 710  * Fix up the uids and gids in posix acl extended attributes in place.
 711  */
 712 static int posix_acl_fix_xattr_common(void *value, size_t size)
 713 {
 714         struct posix_acl_xattr_header *header = value;
 715         int count;
 716
 717         if (!header)
 718                 return -EINVAL;
 719         if (size < sizeof(struct posix_acl_xattr_header))
 720                 return -EINVAL;
 721         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 722                 return -EINVAL;
 723
 724         count = posix_acl_xattr_count(size);
 725         if (count < 0)
 726                 return -EINVAL;
 727         if (count == 0)
 728                 return -EINVAL;
 729
 730         return count;
 731 }
 732
 733 void posix_acl_getxattr_idmapped_mnt(struct user_namespace *mnt_userns,
 734                                      const struct inode *inode,
 735                                      void *value, size_t size)
 736 {
 737         struct posix_acl_xattr_header *header = value;
 738         struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
 739         int count;
 740         vfsuid_t vfsuid;
 741         vfsgid_t vfsgid;
 742         kuid_t uid;
 743         kgid_t gid;
 744
 745         if (no_idmapping(mnt_userns, i_user_ns(inode)))
 746                 return;
 747
 748         count = posix_acl_fix_xattr_common(value, size);
 749         if (count < 0)
 750                 return;
 751
 752         for (end = entry + count; entry != end; entry++) {
 753                 switch (le16_to_cpu(entry->e_tag)) {
 754                 case ACL_USER:
 755                         uid = make_kuid(&init_user_ns, le32_to_cpu(entry->e_id));
 756                         vfsuid = make_vfsuid(mnt_userns, &init_user_ns, uid);
 757                         entry->e_id = cpu_to_le32(from_kuid(&init_user_ns,
 758                                                 vfsuid_into_kuid(vfsuid)));
 759                         break;
 760                 case ACL_GROUP:
 761                         gid = make_kgid(&init_user_ns, le32_to_cpu(entry->e_id));
 762                         vfsgid = make_vfsgid(mnt_userns, &init_user_ns, gid);
 763                         entry->e_id = cpu_to_le32(from_kgid(&init_user_ns,
 764                                                 vfsgid_into_kgid(vfsgid)));
 765                         break;
 766                 default:
 767                         break;
 768                 }
 769         }
 770 }
 771
 772 void posix_acl_setxattr_idmapped_mnt(struct user_namespace *mnt_userns,
 773                                      const struct inode *inode,
 774                                      void *value, size_t size)
 775 {
 776         struct posix_acl_xattr_header *header = value;
 777         struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
 778         int count;
 779         vfsuid_t vfsuid;
 780         vfsgid_t vfsgid;
 781         kuid_t uid;
 782         kgid_t gid;
 783
 784         if (no_idmapping(mnt_userns, i_user_ns(inode)))
 785                 return;
 786
 787         count = posix_acl_fix_xattr_common(value, size);
 788         if (count < 0)
 789                 return;
 790
 791         for (end = entry + count; entry != end; entry++) {
 792                 switch (le16_to_cpu(entry->e_tag)) {
 793                 case ACL_USER:
 794                         uid = make_kuid(&init_user_ns, le32_to_cpu(entry->e_id));
 795                         vfsuid = VFSUIDT_INIT(uid);
 796                         uid = from_vfsuid(mnt_userns, &init_user_ns, vfsuid);
 797                         entry->e_id = cpu_to_le32(from_kuid(&init_user_ns, uid));
 798                         break;
 799                 case ACL_GROUP:
 800                         gid = make_kgid(&init_user_ns, le32_to_cpu(entry->e_id));
 801                         vfsgid = VFSGIDT_INIT(gid);
 802                         gid = from_vfsgid(mnt_userns, &init_user_ns, vfsgid);
 803                         entry->e_id = cpu_to_le32(from_kgid(&init_user_ns, gid));
 804                         break;
 805                 default:
 806                         break;
 807                 }
 808         }
 809 }
 810
 811 static void posix_acl_fix_xattr_userns(
 812         struct user_namespace *to, struct user_namespace *from,
 813         void *value, size_t size)
 814 {
 815         struct posix_acl_xattr_header *header = value;
 816         struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
 817         int count;
 818         kuid_t uid;
 819         kgid_t gid;
 820
 821         count = posix_acl_fix_xattr_common(value, size);
 822         if (count < 0)
 823                 return;
 824
 825         for (end = entry + count; entry != end; entry++) {
 826                 switch(le16_to_cpu(entry->e_tag)) {
 827                 case ACL_USER:
 828                         uid = make_kuid(from, le32_to_cpu(entry->e_id));
 829                         entry->e_id = cpu_to_le32(from_kuid(to, uid));
 830                         break;
 831                 case ACL_GROUP:
 832                         gid = make_kgid(from, le32_to_cpu(entry->e_id));
 833                         entry->e_id = cpu_to_le32(from_kgid(to, gid));
 834                         break;
 835                 default:
 836                         break;
 837                 }
 838         }
 839 }
 840
 841 void posix_acl_fix_xattr_from_user(void *value, size_t size)
 842 {
 843         struct user_namespace *user_ns = current_user_ns();
 844         if (user_ns == &init_user_ns)
 845                 return;
 846         posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
 847 }
 848
 849 void posix_acl_fix_xattr_to_user(void *value, size_t size)
 850 {
 851         struct user_namespace *user_ns = current_user_ns();
 852         if (user_ns == &init_user_ns)
 853                 return;
 854         posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
 855 }
 856
 857 /*
 858  * Convert from extended attribute to in-memory representation.
 859  */
 860 struct posix_acl *
 861 posix_acl_from_xattr(struct user_namespace *user_ns,
 862                      const void *value, size_t size)
 863 {
 864         const struct posix_acl_xattr_header *header = value;
 865         const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
 866         int count;
 867         struct posix_acl *acl;
 868         struct posix_acl_entry *acl_e;
 869
 870         if (!value)
 871                 return NULL;
 872         if (size < sizeof(struct posix_acl_xattr_header))
 873                  return ERR_PTR(-EINVAL);
 874         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 875                 return ERR_PTR(-EOPNOTSUPP);
 876
 877         count = posix_acl_xattr_count(size);
 878         if (count < 0)
 879                 return ERR_PTR(-EINVAL);
 880         if (count == 0)
 881                 return NULL;
 882
 883         acl = posix_acl_alloc(count, GFP_NOFS);
 884         if (!acl)
 885                 return ERR_PTR(-ENOMEM);
 886         acl_e = acl->a_entries;
 887
 888         for (end = entry + count; entry != end; acl_e++, entry++) {
 889                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
 890                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
 891
 892                 switch(acl_e->e_tag) {
 893                         case ACL_USER_OBJ:
 894                         case ACL_GROUP_OBJ:
 895                         case ACL_MASK:
 896                         case ACL_OTHER:
 897                                 break;
 898
 899                         case ACL_USER:
 900                                 acl_e->e_uid =
 901                                         make_kuid(user_ns,
 902                                                   le32_to_cpu(entry->e_id));
 903                                 if (!uid_valid(acl_e->e_uid))
 904                                         goto fail;
 905                                 break;
 906                         case ACL_GROUP:
 907                                 acl_e->e_gid =
 908                                         make_kgid(user_ns,
 909                                                   le32_to_cpu(entry->e_id));
 910                                 if (!gid_valid(acl_e->e_gid))
 911                                         goto fail;
 912                                 break;
 913
 914                         default:
 915                                 goto fail;
 916                 }
 917         }
 918         return acl;
 919
 920 fail:
 921         posix_acl_release(acl);
 922         return ERR_PTR(-EINVAL);
 923 }
 924 EXPORT_SYMBOL (posix_acl_from_xattr);
 925
 926 /*
 927  * Convert from in-memory to extended attribute representation.
 928  */
 929 int
 930 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
 931                    void *buffer, size_t size)
 932 {
 933         struct posix_acl_xattr_header *ext_acl = buffer;
 934         struct posix_acl_xattr_entry *ext_entry;
 935         int real_size, n;
 936
 937         real_size = posix_acl_xattr_size(acl->a_count);
 938         if (!buffer)
 939                 return real_size;
 940         if (real_size > size)
 941                 return -ERANGE;
 942
 943         ext_entry = (void *)(ext_acl + 1);
 944         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
 945
 946         for (n=0; n < acl->a_count; n++, ext_entry++) {
 947                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 948                 ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 949                 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
 950                 switch(acl_e->e_tag) {
 951                 case ACL_USER:
 952                         ext_entry->e_id =
 953                                 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
 954                         break;
 955                 case ACL_GROUP:
 956                         ext_entry->e_id =
 957                                 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
 958                         break;
 959                 default:
 960                         ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
 961                         break;
 962                 }
 963         }
 964         return real_size;
 965 }
 966 EXPORT_SYMBOL (posix_acl_to_xattr);
 967
 968 static int
 969 posix_acl_xattr_get(const struct xattr_handler *handler,
 970                     struct dentry *unused, struct inode *inode,
 971                     const char *name, void *value, size_t size)
 972 {
 973         struct posix_acl *acl;
 974         int error;
 975
 976         if (!IS_POSIXACL(inode))
 977                 return -EOPNOTSUPP;
 978         if (S_ISLNK(inode->i_mode))
 979                 return -EOPNOTSUPP;
 980
 981         acl = get_acl(inode, handler->flags);
 982         if (IS_ERR(acl))
 983                 return PTR_ERR(acl);
 984         if (acl == NULL)
 985                 return -ENODATA;
 986
 987         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 988         posix_acl_release(acl);
 989
 990         return error;
 991 }
 992
 993 int
 994 set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode,
 995               int type, struct posix_acl *acl)
 996 {
 997         if (!IS_POSIXACL(inode))
 998                 return -EOPNOTSUPP;
 999         if (!inode->i_op->set_acl)
1000                 return -EOPNOTSUPP;
1001
1002         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
1003                 return acl ? -EACCES : 0;
1004         if (!inode_owner_or_capable(mnt_userns, inode))
1005                 return -EPERM;
1006
1007         if (acl) {
1008                 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
1009                 if (ret)
1010                         return ret;
1011         }
1012         return inode->i_op->set_acl(mnt_userns, inode, acl, type);
1013 }
1014 EXPORT_SYMBOL(set_posix_acl);
1015
1016 static int
1017 posix_acl_xattr_set(const struct xattr_handler *handler,
1018                            struct user_namespace *mnt_userns,
1019                            struct dentry *unused, struct inode *inode,
1020                            const char *name, const void *value, size_t size,
1021                            int flags)
1022 {
1023         struct posix_acl *acl = NULL;
1024         int ret;
1025
1026         if (value) {
1027                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
1028                 if (IS_ERR(acl))
1029                         return PTR_ERR(acl);
1030         }
1031         ret = set_posix_acl(mnt_userns, inode, handler->flags, acl);
1032         posix_acl_release(acl);
1033         return ret;
1034 }
1035
1036 static bool
1037 posix_acl_xattr_list(struct dentry *dentry)
1038 {
1039         return IS_POSIXACL(d_backing_inode(dentry));
1040 }
1041
1042 const struct xattr_handler posix_acl_access_xattr_handler = {
1043         .name = XATTR_NAME_POSIX_ACL_ACCESS,
1044         .flags = ACL_TYPE_ACCESS,
1045         .list = posix_acl_xattr_list,
1046         .get = posix_acl_xattr_get,
1047         .set = posix_acl_xattr_set,
1048 };
1049 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
1050
1051 const struct xattr_handler posix_acl_default_xattr_handler = {
1052         .name = XATTR_NAME_POSIX_ACL_DEFAULT,
1053         .flags = ACL_TYPE_DEFAULT,
1054         .list = posix_acl_xattr_list,
1055         .get = posix_acl_xattr_get,
1056         .set = posix_acl_xattr_set,
1057 };
1058 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
1059
1060 int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
1061                    struct posix_acl *acl, int type)
1062 {
1063         int error;
1064
1065         if (type == ACL_TYPE_ACCESS) {
1066                 error = posix_acl_update_mode(mnt_userns, inode,
1067                                 &inode->i_mode, &acl);
1068                 if (error)
1069                         return error;
1070         }
1071
1072         inode->i_ctime = current_time(inode);
1073         set_cached_acl(inode, type, acl);
1074         return 0;
1075 }
1076
1077 int simple_acl_create(struct inode *dir, struct inode *inode)
1078 {
1079         struct posix_acl *default_acl, *acl;
1080         int error;
1081
1082         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
1083         if (error)
1084                 return error;
1085
1086         set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
1087         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
1088
1089         if (default_acl)
1090                 posix_acl_release(default_acl);
1091         if (acl)
1092                 posix_acl_release(acl);
1093         return 0;
1094 }