fs/overlayfs/copy_up.c

   1 /*
   2  *
   3  * Copyright (C) 2011 Novell Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/fs.h>
  12 #include <linux/slab.h>
  13 #include <linux/file.h>
  14 #include <linux/splice.h>
  15 #include <linux/xattr.h>
  16 #include <linux/security.h>
  17 #include <linux/uaccess.h>
  18 #include <linux/sched/signal.h>
  19 #include <linux/cred.h>
  20 #include <linux/namei.h>
  21 #include <linux/fdtable.h>
  22 #include <linux/ratelimit.h>
  23 #include <linux/exportfs.h>
  24 #include "overlayfs.h"
  25 #include "ovl_entry.h"
  26
  27 #define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
  28
  29 static bool __read_mostly ovl_check_copy_up;
  30 module_param_named(check_copy_up, ovl_check_copy_up, bool,
  31                    S_IWUSR | S_IRUGO);
  32 MODULE_PARM_DESC(ovl_check_copy_up,
  33                  "Warn on copy-up when causing process also has a R/O fd open");
  34
  35 static int ovl_check_fd(const void *data, struct file *f, unsigned int fd)
  36 {
  37         const struct dentry *dentry = data;
  38
  39         if (file_inode(f) == d_inode(dentry))
  40                 pr_warn_ratelimited("overlayfs: Warning: Copying up %pD, but open R/O on fd %u which will cease to be coherent [pid=%d %s]\n",
  41                                     f, fd, current->pid, current->comm);
  42         return 0;
  43 }
  44
  45 /*
  46  * Check the fds open by this process and warn if something like the following
  47  * scenario is about to occur:
  48  *
  49  *      fd1 = open("foo", O_RDONLY);
  50  *      fd2 = open("foo", O_RDWR);
  51  */
  52 static void ovl_do_check_copy_up(struct dentry *dentry)
  53 {
  54         if (ovl_check_copy_up)
  55                 iterate_fd(current->files, 0, ovl_check_fd, dentry);
  56 }
  57
  58 int ovl_copy_xattr(struct dentry *old, struct dentry *new)
  59 {
  60         ssize_t list_size, size, value_size = 0;
  61         char *buf, *name, *value = NULL;
  62         int uninitialized_var(error);
  63         size_t slen;
  64
  65         if (!(old->d_inode->i_opflags & IOP_XATTR) ||
  66             !(new->d_inode->i_opflags & IOP_XATTR))
  67                 return 0;
  68
  69         list_size = vfs_listxattr(old, NULL, 0);
  70         if (list_size <= 0) {
  71                 if (list_size == -EOPNOTSUPP)
  72                         return 0;
  73                 return list_size;
  74         }
  75
  76         buf = kzalloc(list_size, GFP_KERNEL);
  77         if (!buf)
  78                 return -ENOMEM;
  79
  80         list_size = vfs_listxattr(old, buf, list_size);
  81         if (list_size <= 0) {
  82                 error = list_size;
  83                 goto out;
  84         }
  85
  86         for (name = buf; list_size; name += slen) {
  87                 slen = strnlen(name, list_size) + 1;
  88
  89                 /* underlying fs providing us with an broken xattr list? */
  90                 if (WARN_ON(slen > list_size)) {
  91                         error = -EIO;
  92                         break;
  93                 }
  94                 list_size -= slen;
  95
  96                 if (ovl_is_private_xattr(name))
  97                         continue;
  98 retry:
  99                 size = vfs_getxattr(old, name, value, value_size);
 100                 if (size == -ERANGE)
 101                         size = vfs_getxattr(old, name, NULL, 0);
 102
 103                 if (size < 0) {
 104                         error = size;
 105                         break;
 106                 }
 107
 108                 if (size > value_size) {
 109                         void *new;
 110
 111                         new = krealloc(value, size, GFP_KERNEL);
 112                         if (!new) {
 113                                 error = -ENOMEM;
 114                                 break;
 115                         }
 116                         value = new;
 117                         value_size = size;
 118                         goto retry;
 119                 }
 120
 121                 error = security_inode_copy_up_xattr(name);
 122                 if (error < 0 && error != -EOPNOTSUPP)
 123                         break;
 124                 if (error == 1) {
 125                         error = 0;
 126                         continue; /* Discard */
 127                 }
 128                 error = vfs_setxattr(new, name, value, size, 0);
 129                 if (error)
 130                         break;
 131         }
 132         kfree(value);
 133 out:
 134         kfree(buf);
 135         return error;
 136 }
 137
 138 static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
 139 {
 140         struct file *old_file;
 141         struct file *new_file;
 142         loff_t old_pos = 0;
 143         loff_t new_pos = 0;
 144         int error = 0;
 145
 146         if (len == 0)
 147                 return 0;
 148
 149         old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY);
 150         if (IS_ERR(old_file))
 151                 return PTR_ERR(old_file);
 152
 153         new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
 154         if (IS_ERR(new_file)) {
 155                 error = PTR_ERR(new_file);
 156                 goto out_fput;
 157         }
 158
 159         /* Try to use clone_file_range to clone up within the same fs */
 160         error = vfs_clone_file_range(old_file, 0, new_file, 0, len);
 161         if (!error)
 162                 goto out;
 163         /* Couldn't clone, so now we try to copy the data */
 164         error = 0;
 165
 166         /* FIXME: copy up sparse files efficiently */
 167         while (len) {
 168                 size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
 169                 long bytes;
 170
 171                 if (len < this_len)
 172                         this_len = len;
 173
 174                 if (signal_pending_state(TASK_KILLABLE, current)) {
 175                         error = -EINTR;
 176                         break;
 177                 }
 178
 179                 bytes = do_splice_direct(old_file, &old_pos,
 180                                          new_file, &new_pos,
 181                                          this_len, SPLICE_F_MOVE);
 182                 if (bytes <= 0) {
 183                         error = bytes;
 184                         break;
 185                 }
 186                 WARN_ON(old_pos != new_pos);
 187
 188                 len -= bytes;
 189         }
 190 out:
 191         if (!error)
 192                 error = vfs_fsync(new_file, 0);
 193         fput(new_file);
 194 out_fput:
 195         fput(old_file);
 196         return error;
 197 }
 198
 199 static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
 200 {
 201         struct iattr attr = {
 202                 .ia_valid =
 203                      ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
 204                 .ia_atime = stat->atime,
 205                 .ia_mtime = stat->mtime,
 206         };
 207
 208         return notify_change(upperdentry, &attr, NULL);
 209 }
 210
 211 int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
 212 {
 213         int err = 0;
 214
 215         /*
 216          * For the most part we want to set the mode bits before setting
 217          * the user, otherwise the current context might lack permission
 218          * for setting the mode. However for sxid/sticky bits we want
 219          * the operation to fail if the current user isn't privileged
 220          * towards the resulting inode. So we first set the mode but
 221          * exclude the sxid/sticky bits, then set the user, then set the
 222          * mode again if any of the sxid/sticky bits are set.
 223          */
 224         if (!S_ISLNK(stat->mode)) {
 225                 struct iattr attr = {
 226                         .ia_valid = ATTR_MODE,
 227                         .ia_mode = stat->mode & ~(S_ISUID|S_ISGID|S_ISVTX),
 228                 };
 229                 err = notify_change(upperdentry, &attr, NULL);
 230         }
 231         if (!err) {
 232                 struct iattr attr = {
 233                         .ia_valid = ATTR_UID | ATTR_GID,
 234                         .ia_uid = stat->uid,
 235                         .ia_gid = stat->gid,
 236                 };
 237                 err = notify_change(upperdentry, &attr, NULL);
 238         }
 239         if (!err && !S_ISLNK(stat->mode) &&
 240             (stat->mode & (S_ISUID|S_ISGID|S_ISVTX))) {
 241                 struct iattr attr = {
 242                         .ia_valid = ATTR_MODE,
 243                         .ia_mode = stat->mode,
 244                 };
 245                 err = notify_change(upperdentry, &attr, NULL);
 246         }
 247         if (!err)
 248                 ovl_set_timestamps(upperdentry, stat);
 249
 250         return err;
 251 }
 252
 253 struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper)
 254 {
 255         struct ovl_fh *fh;
 256         int fh_type, fh_len, dwords;
 257         void *buf;
 258         int buflen = MAX_HANDLE_SZ;
 259         uuid_t *uuid = &lower->d_sb->s_uuid;
 260
 261         buf = kmalloc(buflen, GFP_TEMPORARY);
 262         if (!buf)
 263                 return ERR_PTR(-ENOMEM);
 264
 265         /*
 266          * We encode a non-connectable file handle for non-dir, because we
 267          * only need to find the lower inode number and we don't want to pay
 268          * the price or reconnecting the dentry.
 269          */
 270         dwords = buflen >> 2;
 271         fh_type = exportfs_encode_fh(lower, buf, &dwords, 0);
 272         buflen = (dwords << 2);
 273
 274         fh = ERR_PTR(-EIO);
 275         if (WARN_ON(fh_type < 0) ||
 276             WARN_ON(buflen > MAX_HANDLE_SZ) ||
 277             WARN_ON(fh_type == FILEID_INVALID))
 278                 goto out;
 279
 280         BUILD_BUG_ON(MAX_HANDLE_SZ + offsetof(struct ovl_fh, fid) > 255);
 281         fh_len = offsetof(struct ovl_fh, fid) + buflen;
 282         fh = kmalloc(fh_len, GFP_KERNEL);
 283         if (!fh) {
 284                 fh = ERR_PTR(-ENOMEM);
 285                 goto out;
 286         }
 287
 288         fh->version = OVL_FH_VERSION;
 289         fh->magic = OVL_FH_MAGIC;
 290         fh->type = fh_type;
 291         fh->flags = OVL_FH_FLAG_CPU_ENDIAN;
 292         /*
 293          * When we will want to decode an overlay dentry from this handle
 294          * and all layers are on the same fs, if we get a disconncted real
 295          * dentry when we decode fid, the only way to tell if we should assign
 296          * it to upperdentry or to lowerstack is by checking this flag.
 297          */
 298         if (is_upper)
 299                 fh->flags |= OVL_FH_FLAG_PATH_UPPER;
 300         fh->len = fh_len;
 301         fh->uuid = *uuid;
 302         memcpy(fh->fid, buf, buflen);
 303
 304 out:
 305         kfree(buf);
 306         return fh;
 307 }
 308
 309 static int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
 310                           struct dentry *upper)
 311 {
 312         const struct ovl_fh *fh = NULL;
 313         int err;
 314
 315         /*
 316          * When lower layer doesn't support export operations store a 'null' fh,
 317          * so we can use the overlay.origin xattr to distignuish between a copy
 318          * up and a pure upper inode.
 319          */
 320         if (ovl_can_decode_fh(lower->d_sb)) {
 321                 fh = ovl_encode_fh(lower, false);
 322                 if (IS_ERR(fh))
 323                         return PTR_ERR(fh);
 324         }
 325
 326         /*
 327          * Do not fail when upper doesn't support xattrs.
 328          */
 329         err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh,
 330                                  fh ? fh->len : 0, 0);
 331         kfree(fh);
 332
 333         return err;
 334 }
 335
 336 struct ovl_copy_up_ctx {
 337         struct dentry *parent;
 338         struct dentry *dentry;
 339         struct path lowerpath;
 340         struct kstat stat;
 341         struct kstat pstat;
 342         const char *link;
 343         struct dentry *destdir;
 344         struct qstr destname;
 345         struct dentry *workdir;
 346         bool tmpfile;
 347         bool origin;
 348 };
 349
 350 static int ovl_link_up(struct ovl_copy_up_ctx *c)
 351 {
 352         int err;
 353         struct dentry *upper;
 354         struct dentry *upperdir = ovl_dentry_upper(c->parent);
 355         struct inode *udir = d_inode(upperdir);
 356
 357         /* Mark parent "impure" because it may now contain non-pure upper */
 358         err = ovl_set_impure(c->parent, upperdir);
 359         if (err)
 360                 return err;
 361
 362         err = ovl_set_nlink_lower(c->dentry);
 363         if (err)
 364                 return err;
 365
 366         inode_lock_nested(udir, I_MUTEX_PARENT);
 367         upper = lookup_one_len(c->dentry->d_name.name, upperdir,
 368                                c->dentry->d_name.len);
 369         err = PTR_ERR(upper);
 370         if (!IS_ERR(upper)) {
 371                 err = ovl_do_link(ovl_dentry_upper(c->dentry), udir, upper,
 372                                   true);
 373                 dput(upper);
 374
 375                 if (!err) {
 376                         /* Restore timestamps on parent (best effort) */
 377                         ovl_set_timestamps(upperdir, &c->pstat);
 378                         ovl_dentry_set_upper_alias(c->dentry);
 379                 }
 380         }
 381         inode_unlock(udir);
 382         ovl_set_nlink_upper(c->dentry);
 383
 384         return err;
 385 }
 386
 387 static int ovl_install_temp(struct ovl_copy_up_ctx *c, struct dentry *temp,
 388                             struct dentry **newdentry)
 389 {
 390         int err;
 391         struct dentry *upper;
 392         struct inode *udir = d_inode(c->destdir);
 393
 394         upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
 395         if (IS_ERR(upper))
 396                 return PTR_ERR(upper);
 397
 398         if (c->tmpfile)
 399                 err = ovl_do_link(temp, udir, upper, true);
 400         else
 401                 err = ovl_do_rename(d_inode(c->workdir), temp, udir, upper, 0);
 402
 403         if (!err)
 404                 *newdentry = dget(c->tmpfile ? upper : temp);
 405         dput(upper);
 406
 407         return err;
 408 }
 409
 410 static int ovl_get_tmpfile(struct ovl_copy_up_ctx *c, struct dentry **tempp)
 411 {
 412         int err;
 413         struct dentry *temp;
 414         const struct cred *old_creds = NULL;
 415         struct cred *new_creds = NULL;
 416         struct cattr cattr = {
 417                 /* Can't properly set mode on creation because of the umask */
 418                 .mode = c->stat.mode & S_IFMT,
 419                 .rdev = c->stat.rdev,
 420                 .link = c->link
 421         };
 422
 423         err = security_inode_copy_up(c->dentry, &new_creds);
 424         if (err < 0)
 425                 goto out;
 426
 427         if (new_creds)
 428                 old_creds = override_creds(new_creds);
 429
 430         if (c->tmpfile) {
 431                 temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
 432                 if (IS_ERR(temp))
 433                         goto temp_err;
 434         } else {
 435                 temp = ovl_lookup_temp(c->workdir);
 436                 if (IS_ERR(temp))
 437                         goto temp_err;
 438
 439                 err = ovl_create_real(d_inode(c->workdir), temp, &cattr,
 440                                       NULL, true);
 441                 if (err) {
 442                         dput(temp);
 443                         goto out;
 444                 }
 445         }
 446         err = 0;
 447         *tempp = temp;
 448 out:
 449         if (new_creds) {
 450                 revert_creds(old_creds);
 451                 put_cred(new_creds);
 452         }
 453
 454         return err;
 455
 456 temp_err:
 457         err = PTR_ERR(temp);
 458         goto out;
 459 }
 460
 461 static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
 462 {
 463         int err;
 464
 465         if (S_ISREG(c->stat.mode)) {
 466                 struct path upperpath;
 467
 468                 ovl_path_upper(c->dentry, &upperpath);
 469                 BUG_ON(upperpath.dentry != NULL);
 470                 upperpath.dentry = temp;
 471
 472                 err = ovl_copy_up_data(&c->lowerpath, &upperpath, c->stat.size);
 473                 if (err)
 474                         return err;
 475         }
 476
 477         err = ovl_copy_xattr(c->lowerpath.dentry, temp);
 478         if (err)
 479                 return err;
 480
 481         inode_lock(temp->d_inode);
 482         err = ovl_set_attr(temp, &c->stat);
 483         inode_unlock(temp->d_inode);
 484         if (err)
 485                 return err;
 486
 487         /*
 488          * Store identifier of lower inode in upper inode xattr to
 489          * allow lookup of the copy up origin inode.
 490          *
 491          * Don't set origin when we are breaking the association with a lower
 492          * hard link.
 493          */
 494         if (c->origin) {
 495                 err = ovl_set_origin(c->dentry, c->lowerpath.dentry, temp);
 496                 if (err)
 497                         return err;
 498         }
 499
 500         return 0;
 501 }
 502
 503 static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
 504 {
 505         struct inode *udir = c->destdir->d_inode;
 506         struct dentry *newdentry = NULL;
 507         struct dentry *temp = NULL;
 508         int err;
 509
 510         err = ovl_get_tmpfile(c, &temp);
 511         if (err)
 512                 goto out;
 513
 514         err = ovl_copy_up_inode(c, temp);
 515         if (err)
 516                 goto out_cleanup;
 517
 518         if (c->tmpfile) {
 519                 inode_lock_nested(udir, I_MUTEX_PARENT);
 520                 err = ovl_install_temp(c, temp, &newdentry);
 521                 inode_unlock(udir);
 522         } else {
 523                 err = ovl_install_temp(c, temp, &newdentry);
 524         }
 525         if (err)
 526                 goto out_cleanup;
 527
 528         ovl_inode_update(d_inode(c->dentry), newdentry);
 529 out:
 530         dput(temp);
 531         return err;
 532
 533 out_cleanup:
 534         if (!c->tmpfile)
 535                 ovl_cleanup(d_inode(c->workdir), temp);
 536         goto out;
 537 }
 538
 539 /*
 540  * Copy up a single dentry
 541  *
 542  * All renames start with copy up of source if necessary.  The actual
 543  * rename will only proceed once the copy up was successful.  Copy up uses
 544  * upper parent i_mutex for exclusion.  Since rename can change d_parent it
 545  * is possible that the copy up will lock the old parent.  At that point
 546  * the file will have already been copied up anyway.
 547  */
 548 static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
 549 {
 550         int err;
 551         struct ovl_fs *ofs = c->dentry->d_sb->s_fs_info;
 552         bool indexed = false;
 553
 554         if (ovl_indexdir(c->dentry->d_sb) && !S_ISDIR(c->stat.mode) &&
 555             c->stat.nlink > 1)
 556                 indexed = true;
 557
 558         if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || indexed)
 559                 c->origin = true;
 560
 561         if (indexed) {
 562                 c->destdir = ovl_indexdir(c->dentry->d_sb);
 563                 err = ovl_get_index_name(c->lowerpath.dentry, &c->destname);
 564                 if (err)
 565                         return err;
 566         } else {
 567                 /*
 568                  * Mark parent "impure" because it may now contain non-pure
 569                  * upper
 570                  */
 571                 err = ovl_set_impure(c->parent, c->destdir);
 572                 if (err)
 573                         return err;
 574         }
 575
 576         /* Should we copyup with O_TMPFILE or with workdir? */
 577         if (S_ISREG(c->stat.mode) && ofs->tmpfile) {
 578                 c->tmpfile = true;
 579                 err = ovl_copy_up_locked(c);
 580         } else {
 581                 err = ovl_lock_rename_workdir(c->workdir, c->destdir);
 582                 if (!err) {
 583                         err = ovl_copy_up_locked(c);
 584                         unlock_rename(c->workdir, c->destdir);
 585                 }
 586         }
 587
 588         if (indexed) {
 589                 if (!err)
 590                         ovl_set_flag(OVL_INDEX, d_inode(c->dentry));
 591                 kfree(c->destname.name);
 592         } else if (!err) {
 593                 struct inode *udir = d_inode(c->destdir);
 594
 595                 /* Restore timestamps on parent (best effort) */
 596                 inode_lock(udir);
 597                 ovl_set_timestamps(c->destdir, &c->pstat);
 598                 inode_unlock(udir);
 599
 600                 ovl_dentry_set_upper_alias(c->dentry);
 601         }
 602
 603         return err;
 604 }
 605
 606 static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
 607                            int flags)
 608 {
 609         int err;
 610         DEFINE_DELAYED_CALL(done);
 611         struct path parentpath;
 612         struct ovl_copy_up_ctx ctx = {
 613                 .parent = parent,
 614                 .dentry = dentry,
 615                 .workdir = ovl_workdir(dentry),
 616         };
 617
 618         if (WARN_ON(!ctx.workdir))
 619                 return -EROFS;
 620
 621         ovl_path_lower(dentry, &ctx.lowerpath);
 622         err = vfs_getattr(&ctx.lowerpath, &ctx.stat,
 623                           STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
 624         if (err)
 625                 return err;
 626
 627         ovl_path_upper(parent, &parentpath);
 628         ctx.destdir = parentpath.dentry;
 629         ctx.destname = dentry->d_name;
 630
 631         err = vfs_getattr(&parentpath, &ctx.pstat,
 632                           STATX_ATIME | STATX_MTIME, AT_STATX_SYNC_AS_STAT);
 633         if (err)
 634                 return err;
 635
 636         /* maybe truncate regular file. this has no effect on dirs */
 637         if (flags & O_TRUNC)
 638                 ctx.stat.size = 0;
 639
 640         if (S_ISLNK(ctx.stat.mode)) {
 641                 ctx.link = vfs_get_link(ctx.lowerpath.dentry, &done);
 642                 if (IS_ERR(ctx.link))
 643                         return PTR_ERR(ctx.link);
 644         }
 645         ovl_do_check_copy_up(ctx.lowerpath.dentry);
 646
 647         err = ovl_copy_up_start(dentry);
 648         /* err < 0: interrupted, err > 0: raced with another copy-up */
 649         if (unlikely(err)) {
 650                 if (err > 0)
 651                         err = 0;
 652         } else {
 653                 if (!ovl_dentry_upper(dentry))
 654                         err = ovl_do_copy_up(&ctx);
 655                 if (!err && !ovl_dentry_has_upper_alias(dentry))
 656                         err = ovl_link_up(&ctx);
 657                 ovl_copy_up_end(dentry);
 658         }
 659         do_delayed_call(&done);
 660
 661         return err;
 662 }
 663
 664 int ovl_copy_up_flags(struct dentry *dentry, int flags)
 665 {
 666         int err = 0;
 667         const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
 668
 669         while (!err) {
 670                 struct dentry *next;
 671                 struct dentry *parent;
 672
 673                 /*
 674                  * Check if copy-up has happened as well as for upper alias (in
 675                  * case of hard links) is there.
 676                  *
 677                  * Both checks are lockless:
 678                  *  - false negatives: will recheck under oi->lock
 679                  *  - false positives:
 680                  *    + ovl_dentry_upper() uses memory barriers to ensure the
 681                  *      upper dentry is up-to-date
 682                  *    + ovl_dentry_has_upper_alias() relies on locking of
 683                  *      upper parent i_rwsem to prevent reordering copy-up
 684                  *      with rename.
 685                  */
 686                 if (ovl_dentry_upper(dentry) &&
 687                     ovl_dentry_has_upper_alias(dentry))
 688                         break;
 689
 690                 next = dget(dentry);
 691                 /* find the topmost dentry not yet copied up */
 692                 for (;;) {
 693                         parent = dget_parent(next);
 694
 695                         if (ovl_dentry_upper(parent))
 696                                 break;
 697
 698                         dput(next);
 699                         next = parent;
 700                 }
 701
 702                 err = ovl_copy_up_one(parent, next, flags);
 703
 704                 dput(parent);
 705                 dput(next);
 706         }
 707         revert_creds(old_cred);
 708
 709         return err;
 710 }
 711
 712 int ovl_copy_up(struct dentry *dentry)
 713 {
 714         return ovl_copy_up_flags(dentry, 0);
 715 }