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