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         if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED)
 139                 /* fall through */ ;
 140
 141         /*
 142          * Normally, the ACL returned by ->get_acl will be cached.
 143          * A filesystem can prevent that by calling
 144          * forget_cached_acl(inode, type) in ->get_acl.
 145          *
 146          * If the filesystem doesn't have a get_acl() function at all, we'll
 147          * just create the negative cache entry.
 148          */
 149         if (!inode->i_op->get_acl) {
 150                 set_cached_acl(inode, type, NULL);
 151                 return NULL;
 152         }
 153         acl = inode->i_op->get_acl(inode, type, false);
 154
 155         if (IS_ERR(acl)) {
 156                 /*
 157                  * Remove our sentinel so that we don't block future attempts
 158                  * to cache the ACL.
 159                  */
 160                 cmpxchg(p, sentinel, ACL_NOT_CACHED);
 161                 return acl;
 162         }
 163
 164         /*
 165          * Cache the result, but only if our sentinel is still in place.
 166          */
 167         posix_acl_dup(acl);
 168         if (unlikely(cmpxchg(p, sentinel, acl) != sentinel))
 169                 posix_acl_release(acl);
 170         return acl;
 171 }
 172 EXPORT_SYMBOL(get_acl);
 173
 174 /*
 175  * Init a fresh posix_acl
 176  */
 177 void
 178 posix_acl_init(struct posix_acl *acl, int count)
 179 {
 180         refcount_set(&acl->a_refcount, 1);
 181         acl->a_count = count;
 182 }
 183 EXPORT_SYMBOL(posix_acl_init);
 184
 185 /*
 186  * Allocate a new ACL with the specified number of entries.
 187  */
 188 struct posix_acl *
 189 posix_acl_alloc(int count, gfp_t flags)
 190 {
 191         const size_t size = sizeof(struct posix_acl) +
 192                             count * sizeof(struct posix_acl_entry);
 193         struct posix_acl *acl = kmalloc(size, flags);
 194         if (acl)
 195                 posix_acl_init(acl, count);
 196         return acl;
 197 }
 198 EXPORT_SYMBOL(posix_acl_alloc);
 199
 200 /*
 201  * Clone an ACL.
 202  */
 203 static struct posix_acl *
 204 posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
 205 {
 206         struct posix_acl *clone = NULL;
 207
 208         if (acl) {
 209                 int size = sizeof(struct posix_acl) + acl->a_count *
 210                            sizeof(struct posix_acl_entry);
 211                 clone = kmemdup(acl, size, flags);
 212                 if (clone)
 213                         refcount_set(&clone->a_refcount, 1);
 214         }
 215         return clone;
 216 }
 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         kuid_t uid;
 366         kgid_t gid;
 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                                 uid = i_uid_into_mnt(mnt_userns, inode);
 375                                 if (uid_eq(uid, current_fsuid()))
 376                                         goto check_perm;
 377                                 break;
 378                         case ACL_USER:
 379                                 uid = mapped_kuid_fs(mnt_userns,
 380                                                      i_user_ns(inode),
 381                                                      pa->e_uid);
 382                                 if (uid_eq(uid, current_fsuid()))
 383                                         goto mask;
 384                                 break;
 385                         case ACL_GROUP_OBJ:
 386                                 gid = i_gid_into_mnt(mnt_userns, inode);
 387                                 if (in_group_p(gid)) {
 388                                         found = 1;
 389                                         if ((pa->e_perm & want) == want)
 390                                                 goto mask;
 391                                 }
 392                                 break;
 393                         case ACL_GROUP:
 394                                 gid = mapped_kgid_fs(mnt_userns,
 395                                                      i_user_ns(inode),
 396                                                      pa->e_gid);
 397                                 if (in_group_p(gid)) {
 398                                         found = 1;
 399                                         if ((pa->e_perm & want) == want)
 400                                                 goto mask;
 401                                 }
 402                                 break;
 403                         case ACL_MASK:
 404                                 break;
 405                         case ACL_OTHER:
 406                                 if (found)
 407                                         return -EACCES;
 408                                 else
 409                                         goto check_perm;
 410                         default:
 411                                 return -EIO;
 412                 }
 413         }
 414         return -EIO;
 415
 416 mask:
 417         for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
 418                 if (mask_obj->e_tag == ACL_MASK) {
 419                         if ((pa->e_perm & mask_obj->e_perm & want) == want)
 420                                 return 0;
 421                         return -EACCES;
 422                 }
 423         }
 424
 425 check_perm:
 426         if ((pa->e_perm & want) == want)
 427                 return 0;
 428         return -EACCES;
 429 }
 430
 431 /*
 432  * Modify acl when creating a new inode. The caller must ensure the acl is
 433  * only referenced once.
 434  *
 435  * mode_p initially must contain the mode parameter to the open() / creat()
 436  * system calls. All permissions that are not granted by the acl are removed.
 437  * The permissions in the acl are changed to reflect the mode_p parameter.
 438  */
 439 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
 440 {
 441         struct posix_acl_entry *pa, *pe;
 442         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 443         umode_t mode = *mode_p;
 444         int not_equiv = 0;
 445
 446         /* assert(atomic_read(acl->a_refcount) == 1); */
 447
 448         FOREACH_ACL_ENTRY(pa, acl, pe) {
 449                 switch(pa->e_tag) {
 450                         case ACL_USER_OBJ:
 451                                 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
 452                                 mode &= (pa->e_perm << 6) | ~S_IRWXU;
 453                                 break;
 454
 455                         case ACL_USER:
 456                         case ACL_GROUP:
 457                                 not_equiv = 1;
 458                                 break;
 459
 460                         case ACL_GROUP_OBJ:
 461                                 group_obj = pa;
 462                                 break;
 463
 464                         case ACL_OTHER:
 465                                 pa->e_perm &= mode | ~S_IRWXO;
 466                                 mode &= pa->e_perm | ~S_IRWXO;
 467                                 break;
 468
 469                         case ACL_MASK:
 470                                 mask_obj = pa;
 471                                 not_equiv = 1;
 472                                 break;
 473
 474                         default:
 475                                 return -EIO;
 476                 }
 477         }
 478
 479         if (mask_obj) {
 480                 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 481                 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
 482         } else {
 483                 if (!group_obj)
 484                         return -EIO;
 485                 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
 486                 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
 487         }
 488
 489         *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
 490         return not_equiv;
 491 }
 492
 493 /*
 494  * Modify the ACL for the chmod syscall.
 495  */
 496 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
 497 {
 498         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
 499         struct posix_acl_entry *pa, *pe;
 500
 501         /* assert(atomic_read(acl->a_refcount) == 1); */
 502
 503         FOREACH_ACL_ENTRY(pa, acl, pe) {
 504                 switch(pa->e_tag) {
 505                         case ACL_USER_OBJ:
 506                                 pa->e_perm = (mode & S_IRWXU) >> 6;
 507                                 break;
 508
 509                         case ACL_USER:
 510                         case ACL_GROUP:
 511                                 break;
 512
 513                         case ACL_GROUP_OBJ:
 514                                 group_obj = pa;
 515                                 break;
 516
 517                         case ACL_MASK:
 518                                 mask_obj = pa;
 519                                 break;
 520
 521                         case ACL_OTHER:
 522                                 pa->e_perm = (mode & S_IRWXO);
 523                                 break;
 524
 525                         default:
 526                                 return -EIO;
 527                 }
 528         }
 529
 530         if (mask_obj) {
 531                 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
 532         } else {
 533                 if (!group_obj)
 534                         return -EIO;
 535                 group_obj->e_perm = (mode & S_IRWXG) >> 3;
 536         }
 537
 538         return 0;
 539 }
 540
 541 int
 542 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
 543 {
 544         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 545         int err = -ENOMEM;
 546         if (clone) {
 547                 err = posix_acl_create_masq(clone, mode_p);
 548                 if (err < 0) {
 549                         posix_acl_release(clone);
 550                         clone = NULL;
 551                 }
 552         }
 553         posix_acl_release(*acl);
 554         *acl = clone;
 555         return err;
 556 }
 557 EXPORT_SYMBOL(__posix_acl_create);
 558
 559 int
 560 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
 561 {
 562         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
 563         int err = -ENOMEM;
 564         if (clone) {
 565                 err = __posix_acl_chmod_masq(clone, mode);
 566                 if (err) {
 567                         posix_acl_release(clone);
 568                         clone = NULL;
 569                 }
 570         }
 571         posix_acl_release(*acl);
 572         *acl = clone;
 573         return err;
 574 }
 575 EXPORT_SYMBOL(__posix_acl_chmod);
 576
 577 /**
 578  * posix_acl_chmod - chmod a posix acl
 579  *
 580  * @mnt_userns: user namespace of the mount @inode was found from
 581  * @inode:      inode to check permissions on
 582  * @mode:       the new mode of @inode
 583  *
 584  * If the inode has been found through an idmapped mount the user namespace of
 585  * the vfsmount must be passed through @mnt_userns. This function will then
 586  * take care to map the inode according to @mnt_userns before checking
 587  * permissions. On non-idmapped mounts or if permission checking is to be
 588  * performed on the raw inode simply passs init_user_ns.
 589  */
 590 int
 591  posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode,
 592                     umode_t mode)
 593 {
 594         struct posix_acl *acl;
 595         int ret = 0;
 596
 597         if (!IS_POSIXACL(inode))
 598                 return 0;
 599         if (!inode->i_op->set_acl)
 600                 return -EOPNOTSUPP;
 601
 602         acl = get_acl(inode, ACL_TYPE_ACCESS);
 603         if (IS_ERR_OR_NULL(acl)) {
 604                 if (acl == ERR_PTR(-EOPNOTSUPP))
 605                         return 0;
 606                 return PTR_ERR(acl);
 607         }
 608
 609         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 610         if (ret)
 611                 return ret;
 612         ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS);
 613         posix_acl_release(acl);
 614         return ret;
 615 }
 616 EXPORT_SYMBOL(posix_acl_chmod);
 617
 618 int
 619 posix_acl_create(struct inode *dir, umode_t *mode,
 620                 struct posix_acl **default_acl, struct posix_acl **acl)
 621 {
 622         struct posix_acl *p;
 623         struct posix_acl *clone;
 624         int ret;
 625
 626         *acl = NULL;
 627         *default_acl = NULL;
 628
 629         if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
 630                 return 0;
 631
 632         p = get_acl(dir, ACL_TYPE_DEFAULT);
 633         if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
 634                 *mode &= ~current_umask();
 635                 return 0;
 636         }
 637         if (IS_ERR(p))
 638                 return PTR_ERR(p);
 639
 640         ret = -ENOMEM;
 641         clone = posix_acl_clone(p, GFP_NOFS);
 642         if (!clone)
 643                 goto err_release;
 644
 645         ret = posix_acl_create_masq(clone, mode);
 646         if (ret < 0)
 647                 goto err_release_clone;
 648
 649         if (ret == 0)
 650                 posix_acl_release(clone);
 651         else
 652                 *acl = clone;
 653
 654         if (!S_ISDIR(*mode))
 655                 posix_acl_release(p);
 656         else
 657                 *default_acl = p;
 658
 659         return 0;
 660
 661 err_release_clone:
 662         posix_acl_release(clone);
 663 err_release:
 664         posix_acl_release(p);
 665         return ret;
 666 }
 667 EXPORT_SYMBOL_GPL(posix_acl_create);
 668
 669 /**
 670  * posix_acl_update_mode  -  update mode in set_acl
 671  * @mnt_userns: user namespace of the mount @inode was found from
 672  * @inode:      target inode
 673  * @mode_p:     mode (pointer) for update
 674  * @acl:        acl pointer
 675  *
 676  * Update the file mode when setting an ACL: compute the new file permission
 677  * bits based on the ACL.  In addition, if the ACL is equivalent to the new
 678  * file mode, set *@acl to NULL to indicate that no ACL should be set.
 679  *
 680  * As with chmod, clear the setgid bit if the caller is not in the owning group
 681  * or capable of CAP_FSETID (see inode_change_ok).
 682  *
 683  * If the inode has been found through an idmapped mount the user namespace of
 684  * the vfsmount must be passed through @mnt_userns. This function will then
 685  * take care to map the inode according to @mnt_userns before checking
 686  * permissions. On non-idmapped mounts or if permission checking is to be
 687  * performed on the raw inode simply passs init_user_ns.
 688  *
 689  * Called from set_acl inode operations.
 690  */
 691 int posix_acl_update_mode(struct user_namespace *mnt_userns,
 692                           struct inode *inode, umode_t *mode_p,
 693                           struct posix_acl **acl)
 694 {
 695         umode_t mode = inode->i_mode;
 696         int error;
 697
 698         error = posix_acl_equiv_mode(*acl, &mode);
 699         if (error < 0)
 700                 return error;
 701         if (error == 0)
 702                 *acl = NULL;
 703         if (!in_group_p(i_gid_into_mnt(mnt_userns, inode)) &&
 704             !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
 705                 mode &= ~S_ISGID;
 706         *mode_p = mode;
 707         return 0;
 708 }
 709 EXPORT_SYMBOL(posix_acl_update_mode);
 710
 711 /*
 712  * Fix up the uids and gids in posix acl extended attributes in place.
 713  */
 714 static void posix_acl_fix_xattr_userns(
 715         struct user_namespace *to, struct user_namespace *from,
 716         struct user_namespace *mnt_userns,
 717         void *value, size_t size, bool from_user)
 718 {
 719         struct posix_acl_xattr_header *header = value;
 720         struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
 721         int count;
 722         kuid_t uid;
 723         kgid_t gid;
 724
 725         if (!value)
 726                 return;
 727         if (size < sizeof(struct posix_acl_xattr_header))
 728                 return;
 729         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 730                 return;
 731
 732         count = posix_acl_xattr_count(size);
 733         if (count < 0)
 734                 return;
 735         if (count == 0)
 736                 return;
 737
 738         for (end = entry + count; entry != end; entry++) {
 739                 switch(le16_to_cpu(entry->e_tag)) {
 740                 case ACL_USER:
 741                         uid = make_kuid(from, le32_to_cpu(entry->e_id));
 742                         if (from_user)
 743                                 uid = mapped_kuid_user(mnt_userns, &init_user_ns, uid);
 744                         else
 745                                 uid = mapped_kuid_fs(mnt_userns, &init_user_ns, uid);
 746                         entry->e_id = cpu_to_le32(from_kuid(to, uid));
 747                         break;
 748                 case ACL_GROUP:
 749                         gid = make_kgid(from, le32_to_cpu(entry->e_id));
 750                         if (from_user)
 751                                 gid = mapped_kgid_user(mnt_userns, &init_user_ns, gid);
 752                         else
 753                                 gid = mapped_kgid_fs(mnt_userns, &init_user_ns, gid);
 754                         entry->e_id = cpu_to_le32(from_kgid(to, gid));
 755                         break;
 756                 default:
 757                         break;
 758                 }
 759         }
 760 }
 761
 762 void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns,
 763                                    struct inode *inode,
 764                                    void *value, size_t size)
 765 {
 766         struct user_namespace *user_ns = current_user_ns();
 767
 768         /* Leave ids untouched on non-idmapped mounts. */
 769         if (no_idmapping(mnt_userns, i_user_ns(inode)))
 770                 mnt_userns = &init_user_ns;
 771         if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
 772                 return;
 773         posix_acl_fix_xattr_userns(&init_user_ns, user_ns, mnt_userns, value,
 774                                    size, true);
 775 }
 776
 777 void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns,
 778                                  struct inode *inode,
 779                                  void *value, size_t size)
 780 {
 781         struct user_namespace *user_ns = current_user_ns();
 782
 783         /* Leave ids untouched on non-idmapped mounts. */
 784         if (no_idmapping(mnt_userns, i_user_ns(inode)))
 785                 mnt_userns = &init_user_ns;
 786         if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
 787                 return;
 788         posix_acl_fix_xattr_userns(user_ns, &init_user_ns, mnt_userns, value,
 789                                    size, false);
 790 }
 791
 792 /*
 793  * Convert from extended attribute to in-memory representation.
 794  */
 795 struct posix_acl *
 796 posix_acl_from_xattr(struct user_namespace *user_ns,
 797                      const void *value, size_t size)
 798 {
 799         const struct posix_acl_xattr_header *header = value;
 800         const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
 801         int count;
 802         struct posix_acl *acl;
 803         struct posix_acl_entry *acl_e;
 804
 805         if (!value)
 806                 return NULL;
 807         if (size < sizeof(struct posix_acl_xattr_header))
 808                  return ERR_PTR(-EINVAL);
 809         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
 810                 return ERR_PTR(-EOPNOTSUPP);
 811
 812         count = posix_acl_xattr_count(size);
 813         if (count < 0)
 814                 return ERR_PTR(-EINVAL);
 815         if (count == 0)
 816                 return NULL;
 817
 818         acl = posix_acl_alloc(count, GFP_NOFS);
 819         if (!acl)
 820                 return ERR_PTR(-ENOMEM);
 821         acl_e = acl->a_entries;
 822
 823         for (end = entry + count; entry != end; acl_e++, entry++) {
 824                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
 825                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
 826
 827                 switch(acl_e->e_tag) {
 828                         case ACL_USER_OBJ:
 829                         case ACL_GROUP_OBJ:
 830                         case ACL_MASK:
 831                         case ACL_OTHER:
 832                                 break;
 833
 834                         case ACL_USER:
 835                                 acl_e->e_uid =
 836                                         make_kuid(user_ns,
 837                                                   le32_to_cpu(entry->e_id));
 838                                 if (!uid_valid(acl_e->e_uid))
 839                                         goto fail;
 840                                 break;
 841                         case ACL_GROUP:
 842                                 acl_e->e_gid =
 843                                         make_kgid(user_ns,
 844                                                   le32_to_cpu(entry->e_id));
 845                                 if (!gid_valid(acl_e->e_gid))
 846                                         goto fail;
 847                                 break;
 848
 849                         default:
 850                                 goto fail;
 851                 }
 852         }
 853         return acl;
 854
 855 fail:
 856         posix_acl_release(acl);
 857         return ERR_PTR(-EINVAL);
 858 }
 859 EXPORT_SYMBOL (posix_acl_from_xattr);
 860
 861 /*
 862  * Convert from in-memory to extended attribute representation.
 863  */
 864 int
 865 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
 866                    void *buffer, size_t size)
 867 {
 868         struct posix_acl_xattr_header *ext_acl = buffer;
 869         struct posix_acl_xattr_entry *ext_entry;
 870         int real_size, n;
 871
 872         real_size = posix_acl_xattr_size(acl->a_count);
 873         if (!buffer)
 874                 return real_size;
 875         if (real_size > size)
 876                 return -ERANGE;
 877
 878         ext_entry = (void *)(ext_acl + 1);
 879         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
 880
 881         for (n=0; n < acl->a_count; n++, ext_entry++) {
 882                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 883                 ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 884                 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
 885                 switch(acl_e->e_tag) {
 886                 case ACL_USER:
 887                         ext_entry->e_id =
 888                                 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
 889                         break;
 890                 case ACL_GROUP:
 891                         ext_entry->e_id =
 892                                 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
 893                         break;
 894                 default:
 895                         ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
 896                         break;
 897                 }
 898         }
 899         return real_size;
 900 }
 901 EXPORT_SYMBOL (posix_acl_to_xattr);
 902
 903 static int
 904 posix_acl_xattr_get(const struct xattr_handler *handler,
 905                     struct dentry *unused, struct inode *inode,
 906                     const char *name, void *value, size_t size)
 907 {
 908         struct posix_acl *acl;
 909         int error;
 910
 911         if (!IS_POSIXACL(inode))
 912                 return -EOPNOTSUPP;
 913         if (S_ISLNK(inode->i_mode))
 914                 return -EOPNOTSUPP;
 915
 916         acl = get_acl(inode, handler->flags);
 917         if (IS_ERR(acl))
 918                 return PTR_ERR(acl);
 919         if (acl == NULL)
 920                 return -ENODATA;
 921
 922         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 923         posix_acl_release(acl);
 924
 925         return error;
 926 }
 927
 928 int
 929 set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode,
 930               int type, struct posix_acl *acl)
 931 {
 932         if (!IS_POSIXACL(inode))
 933                 return -EOPNOTSUPP;
 934         if (!inode->i_op->set_acl)
 935                 return -EOPNOTSUPP;
 936
 937         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 938                 return acl ? -EACCES : 0;
 939         if (!inode_owner_or_capable(mnt_userns, inode))
 940                 return -EPERM;
 941
 942         if (acl) {
 943                 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
 944                 if (ret)
 945                         return ret;
 946         }
 947         return inode->i_op->set_acl(mnt_userns, inode, acl, type);
 948 }
 949 EXPORT_SYMBOL(set_posix_acl);
 950
 951 static int
 952 posix_acl_xattr_set(const struct xattr_handler *handler,
 953                            struct user_namespace *mnt_userns,
 954                            struct dentry *unused, struct inode *inode,
 955                            const char *name, const void *value, size_t size,
 956                            int flags)
 957 {
 958         struct posix_acl *acl = NULL;
 959         int ret;
 960
 961         if (value) {
 962                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 963                 if (IS_ERR(acl))
 964                         return PTR_ERR(acl);
 965         }
 966         ret = set_posix_acl(mnt_userns, inode, handler->flags, acl);
 967         posix_acl_release(acl);
 968         return ret;
 969 }
 970
 971 static bool
 972 posix_acl_xattr_list(struct dentry *dentry)
 973 {
 974         return IS_POSIXACL(d_backing_inode(dentry));
 975 }
 976
 977 const struct xattr_handler posix_acl_access_xattr_handler = {
 978         .name = XATTR_NAME_POSIX_ACL_ACCESS,
 979         .flags = ACL_TYPE_ACCESS,
 980         .list = posix_acl_xattr_list,
 981         .get = posix_acl_xattr_get,
 982         .set = posix_acl_xattr_set,
 983 };
 984 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
 985
 986 const struct xattr_handler posix_acl_default_xattr_handler = {
 987         .name = XATTR_NAME_POSIX_ACL_DEFAULT,
 988         .flags = ACL_TYPE_DEFAULT,
 989         .list = posix_acl_xattr_list,
 990         .get = posix_acl_xattr_get,
 991         .set = posix_acl_xattr_set,
 992 };
 993 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
 994
 995 int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
 996                    struct posix_acl *acl, int type)
 997 {
 998         int error;
 999
1000         if (type == ACL_TYPE_ACCESS) {
1001                 error = posix_acl_update_mode(mnt_userns, inode,
1002                                 &inode->i_mode, &acl);
1003                 if (error)
1004                         return error;
1005         }
1006
1007         inode->i_ctime = current_time(inode);
1008         set_cached_acl(inode, type, acl);
1009         return 0;
1010 }
1011
1012 int simple_acl_create(struct inode *dir, struct inode *inode)
1013 {
1014         struct posix_acl *default_acl, *acl;
1015         int error;
1016
1017         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
1018         if (error)
1019                 return error;
1020
1021         set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
1022         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
1023
1024         if (default_acl)
1025                 posix_acl_release(default_acl);
1026         if (acl)
1027                 posix_acl_release(acl);
1028         return 0;
1029 }