fs/overlayfs/dir.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/fs.h>
  11 #include <linux/namei.h>
  12 #include <linux/xattr.h>
  13 #include <linux/security.h>
  14 #include <linux/cred.h>
  15 #include "overlayfs.h"
  16
  17 void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
  18 {
  19         int err;
  20
  21         dget(wdentry);
  22         if (S_ISDIR(wdentry->d_inode->i_mode))
  23                 err = ovl_do_rmdir(wdir, wdentry);
  24         else
  25                 err = ovl_do_unlink(wdir, wdentry);
  26         dput(wdentry);
  27
  28         if (err) {
  29                 pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
  30                        wdentry, err);
  31         }
  32 }
  33
  34 struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry)
  35 {
  36         struct dentry *temp;
  37         char name[20];
  38
  39         snprintf(name, sizeof(name), "#%lx", (unsigned long) dentry);
  40
  41         temp = lookup_one_len(name, workdir, strlen(name));
  42         if (!IS_ERR(temp) && temp->d_inode) {
  43                 pr_err("overlayfs: workdir/%s already exists\n", name);
  44                 dput(temp);
  45                 temp = ERR_PTR(-EIO);
  46         }
  47
  48         return temp;
  49 }
  50
  51 /* caller holds i_mutex on workdir */
  52 static struct dentry *ovl_whiteout(struct dentry *workdir,
  53                                    struct dentry *dentry)
  54 {
  55         int err;
  56         struct dentry *whiteout;
  57         struct inode *wdir = workdir->d_inode;
  58
  59         whiteout = ovl_lookup_temp(workdir, dentry);
  60         if (IS_ERR(whiteout))
  61                 return whiteout;
  62
  63         err = ovl_do_whiteout(wdir, whiteout);
  64         if (err) {
  65                 dput(whiteout);
  66                 whiteout = ERR_PTR(err);
  67         }
  68
  69         return whiteout;
  70 }
  71
  72 int ovl_create_real(struct inode *dir, struct dentry *newdentry,
  73                     struct kstat *stat, const char *link,
  74                     struct dentry *hardlink, bool debug)
  75 {
  76         int err;
  77
  78         if (newdentry->d_inode)
  79                 return -ESTALE;
  80
  81         if (hardlink) {
  82                 err = ovl_do_link(hardlink, dir, newdentry, debug);
  83         } else {
  84                 switch (stat->mode & S_IFMT) {
  85                 case S_IFREG:
  86                         err = ovl_do_create(dir, newdentry, stat->mode, debug);
  87                         break;
  88
  89                 case S_IFDIR:
  90                         err = ovl_do_mkdir(dir, newdentry, stat->mode, debug);
  91                         break;
  92
  93                 case S_IFCHR:
  94                 case S_IFBLK:
  95                 case S_IFIFO:
  96                 case S_IFSOCK:
  97                         err = ovl_do_mknod(dir, newdentry,
  98                                            stat->mode, stat->rdev, debug);
  99                         break;
 100
 101                 case S_IFLNK:
 102                         err = ovl_do_symlink(dir, newdentry, link, debug);
 103                         break;
 104
 105                 default:
 106                         err = -EPERM;
 107                 }
 108         }
 109         if (!err && WARN_ON(!newdentry->d_inode)) {
 110                 /*
 111                  * Not quite sure if non-instantiated dentry is legal or not.
 112                  * VFS doesn't seem to care so check and warn here.
 113                  */
 114                 err = -ENOENT;
 115         }
 116         return err;
 117 }
 118
 119 static int ovl_set_opaque(struct dentry *upperdentry)
 120 {
 121         return ovl_do_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0);
 122 }
 123
 124 static void ovl_remove_opaque(struct dentry *upperdentry)
 125 {
 126         int err;
 127
 128         err = ovl_do_removexattr(upperdentry, ovl_opaque_xattr);
 129         if (err) {
 130                 pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n",
 131                         upperdentry->d_name.name, err);
 132         }
 133 }
 134
 135 static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
 136                          struct kstat *stat)
 137 {
 138         int err;
 139         enum ovl_path_type type;
 140         struct path realpath;
 141
 142         type = ovl_path_real(dentry, &realpath);
 143         err = vfs_getattr(&realpath, stat);
 144         if (err)
 145                 return err;
 146
 147         stat->dev = dentry->d_sb->s_dev;
 148         stat->ino = dentry->d_inode->i_ino;
 149
 150         /*
 151          * It's probably not worth it to count subdirs to get the
 152          * correct link count.  nlink=1 seems to pacify 'find' and
 153          * other utilities.
 154          */
 155         if (type == OVL_PATH_MERGE)
 156                 stat->nlink = 1;
 157
 158         return 0;
 159 }
 160
 161 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
 162                             struct kstat *stat, const char *link,
 163                             struct dentry *hardlink)
 164 {
 165         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 166         struct inode *udir = upperdir->d_inode;
 167         struct dentry *newdentry;
 168         int err;
 169
 170         mutex_lock_nested(&udir->i_mutex, I_MUTEX_PARENT);
 171         newdentry = lookup_one_len(dentry->d_name.name, upperdir,
 172                                    dentry->d_name.len);
 173         err = PTR_ERR(newdentry);
 174         if (IS_ERR(newdentry))
 175                 goto out_unlock;
 176         err = ovl_create_real(udir, newdentry, stat, link, hardlink, false);
 177         if (err)
 178                 goto out_dput;
 179
 180         ovl_dentry_version_inc(dentry->d_parent);
 181         ovl_dentry_update(dentry, newdentry);
 182         ovl_copyattr(newdentry->d_inode, inode);
 183         d_instantiate(dentry, inode);
 184         newdentry = NULL;
 185 out_dput:
 186         dput(newdentry);
 187 out_unlock:
 188         mutex_unlock(&udir->i_mutex);
 189         return err;
 190 }
 191
 192 static int ovl_lock_rename_workdir(struct dentry *workdir,
 193                                    struct dentry *upperdir)
 194 {
 195         /* Workdir should not be the same as upperdir */
 196         if (workdir == upperdir)
 197                 goto err;
 198
 199         /* Workdir should not be subdir of upperdir and vice versa */
 200         if (lock_rename(workdir, upperdir) != NULL)
 201                 goto err_unlock;
 202
 203         return 0;
 204
 205 err_unlock:
 206         unlock_rename(workdir, upperdir);
 207 err:
 208         pr_err("overlayfs: failed to lock workdir+upperdir\n");
 209         return -EIO;
 210 }
 211
 212 static struct dentry *ovl_clear_empty(struct dentry *dentry,
 213                                       struct list_head *list)
 214 {
 215         struct dentry *workdir = ovl_workdir(dentry);
 216         struct inode *wdir = workdir->d_inode;
 217         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 218         struct inode *udir = upperdir->d_inode;
 219         struct path upperpath;
 220         struct dentry *upper;
 221         struct dentry *opaquedir;
 222         struct kstat stat;
 223         int err;
 224
 225         err = ovl_lock_rename_workdir(workdir, upperdir);
 226         if (err)
 227                 goto out;
 228
 229         ovl_path_upper(dentry, &upperpath);
 230         err = vfs_getattr(&upperpath, &stat);
 231         if (err)
 232                 goto out_unlock;
 233
 234         err = -ESTALE;
 235         if (!S_ISDIR(stat.mode))
 236                 goto out_unlock;
 237         upper = upperpath.dentry;
 238         if (upper->d_parent->d_inode != udir)
 239                 goto out_unlock;
 240
 241         opaquedir = ovl_lookup_temp(workdir, dentry);
 242         err = PTR_ERR(opaquedir);
 243         if (IS_ERR(opaquedir))
 244                 goto out_unlock;
 245
 246         err = ovl_create_real(wdir, opaquedir, &stat, NULL, NULL, true);
 247         if (err)
 248                 goto out_dput;
 249
 250         err = ovl_copy_xattr(upper, opaquedir);
 251         if (err)
 252                 goto out_cleanup;
 253
 254         err = ovl_set_opaque(opaquedir);
 255         if (err)
 256                 goto out_cleanup;
 257
 258         mutex_lock(&opaquedir->d_inode->i_mutex);
 259         err = ovl_set_attr(opaquedir, &stat);
 260         mutex_unlock(&opaquedir->d_inode->i_mutex);
 261         if (err)
 262                 goto out_cleanup;
 263
 264         err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
 265         if (err)
 266                 goto out_cleanup;
 267
 268         ovl_cleanup_whiteouts(upper, list);
 269         ovl_cleanup(wdir, upper);
 270         unlock_rename(workdir, upperdir);
 271
 272         /* dentry's upper doesn't match now, get rid of it */
 273         d_drop(dentry);
 274
 275         return opaquedir;
 276
 277 out_cleanup:
 278         ovl_cleanup(wdir, opaquedir);
 279 out_dput:
 280         dput(opaquedir);
 281 out_unlock:
 282         unlock_rename(workdir, upperdir);
 283 out:
 284         return ERR_PTR(err);
 285 }
 286
 287 static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry,
 288                                                 enum ovl_path_type type)
 289 {
 290         int err;
 291         struct dentry *ret = NULL;
 292         LIST_HEAD(list);
 293
 294         err = ovl_check_empty_dir(dentry, &list);
 295         if (err)
 296                 ret = ERR_PTR(err);
 297         else if (type == OVL_PATH_MERGE)
 298                 ret = ovl_clear_empty(dentry, &list);
 299
 300         ovl_cache_free(&list);
 301
 302         return ret;
 303 }
 304
 305 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 306                                     struct kstat *stat, const char *link,
 307                                     struct dentry *hardlink)
 308 {
 309         struct dentry *workdir = ovl_workdir(dentry);
 310         struct inode *wdir = workdir->d_inode;
 311         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 312         struct inode *udir = upperdir->d_inode;
 313         struct dentry *upper;
 314         struct dentry *newdentry;
 315         int err;
 316
 317         err = ovl_lock_rename_workdir(workdir, upperdir);
 318         if (err)
 319                 goto out;
 320
 321         newdentry = ovl_lookup_temp(workdir, dentry);
 322         err = PTR_ERR(newdentry);
 323         if (IS_ERR(newdentry))
 324                 goto out_unlock;
 325
 326         upper = lookup_one_len(dentry->d_name.name, upperdir,
 327                                dentry->d_name.len);
 328         err = PTR_ERR(upper);
 329         if (IS_ERR(upper))
 330                 goto out_dput;
 331
 332         err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
 333         if (err)
 334                 goto out_dput2;
 335
 336         if (S_ISDIR(stat->mode)) {
 337                 err = ovl_set_opaque(newdentry);
 338                 if (err)
 339                         goto out_cleanup;
 340
 341                 err = ovl_do_rename(wdir, newdentry, udir, upper,
 342                                     RENAME_EXCHANGE);
 343                 if (err)
 344                         goto out_cleanup;
 345
 346                 ovl_cleanup(wdir, upper);
 347         } else {
 348                 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
 349                 if (err)
 350                         goto out_cleanup;
 351         }
 352         ovl_dentry_version_inc(dentry->d_parent);
 353         ovl_dentry_update(dentry, newdentry);
 354         ovl_copyattr(newdentry->d_inode, inode);
 355         d_instantiate(dentry, inode);
 356         newdentry = NULL;
 357 out_dput2:
 358         dput(upper);
 359 out_dput:
 360         dput(newdentry);
 361 out_unlock:
 362         unlock_rename(workdir, upperdir);
 363 out:
 364         return err;
 365
 366 out_cleanup:
 367         ovl_cleanup(wdir, newdentry);
 368         goto out_dput2;
 369 }
 370
 371 static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
 372                               const char *link, struct dentry *hardlink)
 373 {
 374         int err;
 375         struct inode *inode;
 376         struct kstat stat = {
 377                 .mode = mode,
 378                 .rdev = rdev,
 379         };
 380
 381         err = -ENOMEM;
 382         inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
 383         if (!inode)
 384                 goto out;
 385
 386         err = ovl_copy_up(dentry->d_parent);
 387         if (err)
 388                 goto out_iput;
 389
 390         if (!ovl_dentry_is_opaque(dentry)) {
 391                 err = ovl_create_upper(dentry, inode, &stat, link, hardlink);
 392         } else {
 393                 const struct cred *old_cred;
 394                 struct cred *override_cred;
 395
 396                 err = -ENOMEM;
 397                 override_cred = prepare_creds();
 398                 if (!override_cred)
 399                         goto out_iput;
 400
 401                 /*
 402                  * CAP_SYS_ADMIN for setting opaque xattr
 403                  * CAP_DAC_OVERRIDE for create in workdir, rename
 404                  * CAP_FOWNER for removing whiteout from sticky dir
 405                  */
 406                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
 407                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
 408                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
 409                 old_cred = override_creds(override_cred);
 410
 411                 err = ovl_create_over_whiteout(dentry, inode, &stat, link,
 412                                                hardlink);
 413
 414                 revert_creds(old_cred);
 415                 put_cred(override_cred);
 416         }
 417
 418         if (!err)
 419                 inode = NULL;
 420 out_iput:
 421         iput(inode);
 422 out:
 423         return err;
 424 }
 425
 426 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 427                              const char *link)
 428 {
 429         int err;
 430
 431         err = ovl_want_write(dentry);
 432         if (!err) {
 433                 err = ovl_create_or_link(dentry, mode, rdev, link, NULL);
 434                 ovl_drop_write(dentry);
 435         }
 436
 437         return err;
 438 }
 439
 440 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 441                       bool excl)
 442 {
 443         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 444 }
 445
 446 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 447 {
 448         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 449 }
 450
 451 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 452                      dev_t rdev)
 453 {
 454         /* Don't allow creation of "whiteout" on overlay */
 455         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
 456                 return -EPERM;
 457
 458         return ovl_create_object(dentry, mode, rdev, NULL);
 459 }
 460
 461 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
 462                        const char *link)
 463 {
 464         return ovl_create_object(dentry, S_IFLNK, 0, link);
 465 }
 466
 467 static int ovl_link(struct dentry *old, struct inode *newdir,
 468                     struct dentry *new)
 469 {
 470         int err;
 471         struct dentry *upper;
 472
 473         err = ovl_want_write(old);
 474         if (err)
 475                 goto out;
 476
 477         err = ovl_copy_up(old);
 478         if (err)
 479                 goto out_drop_write;
 480
 481         upper = ovl_dentry_upper(old);
 482         err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper);
 483
 484 out_drop_write:
 485         ovl_drop_write(old);
 486 out:
 487         return err;
 488 }
 489
 490 static int ovl_remove_and_whiteout(struct dentry *dentry,
 491                                    enum ovl_path_type type, bool is_dir)
 492 {
 493         struct dentry *workdir = ovl_workdir(dentry);
 494         struct inode *wdir = workdir->d_inode;
 495         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 496         struct inode *udir = upperdir->d_inode;
 497         struct dentry *whiteout;
 498         struct dentry *upper;
 499         struct dentry *opaquedir = NULL;
 500         int err;
 501
 502         if (is_dir) {
 503                 opaquedir = ovl_check_empty_and_clear(dentry, type);
 504                 err = PTR_ERR(opaquedir);
 505                 if (IS_ERR(opaquedir))
 506                         goto out;
 507         }
 508
 509         err = ovl_lock_rename_workdir(workdir, upperdir);
 510         if (err)
 511                 goto out_dput;
 512
 513         whiteout = ovl_whiteout(workdir, dentry);
 514         err = PTR_ERR(whiteout);
 515         if (IS_ERR(whiteout))
 516                 goto out_unlock;
 517
 518         if (type == OVL_PATH_LOWER) {
 519                 upper = lookup_one_len(dentry->d_name.name, upperdir,
 520                                            dentry->d_name.len);
 521                 err = PTR_ERR(upper);
 522                 if (IS_ERR(upper))
 523                         goto kill_whiteout;
 524
 525                 err = ovl_do_rename(wdir, whiteout, udir, upper, 0);
 526                 dput(upper);
 527                 if (err)
 528                         goto kill_whiteout;
 529         } else {
 530                 int flags = 0;
 531
 532                 upper = ovl_dentry_upper(dentry);
 533                 if (opaquedir)
 534                         upper = opaquedir;
 535                 err = -ESTALE;
 536                 if (upper->d_parent != upperdir)
 537                         goto kill_whiteout;
 538
 539                 if (is_dir)
 540                         flags |= RENAME_EXCHANGE;
 541
 542                 err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
 543                 if (err)
 544                         goto kill_whiteout;
 545
 546                 if (is_dir)
 547                         ovl_cleanup(wdir, upper);
 548         }
 549         ovl_dentry_version_inc(dentry->d_parent);
 550 out_d_drop:
 551         d_drop(dentry);
 552         dput(whiteout);
 553 out_unlock:
 554         unlock_rename(workdir, upperdir);
 555 out_dput:
 556         dput(opaquedir);
 557 out:
 558         return err;
 559
 560 kill_whiteout:
 561         ovl_cleanup(wdir, whiteout);
 562         goto out_d_drop;
 563 }
 564
 565 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
 566 {
 567         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 568         struct inode *dir = upperdir->d_inode;
 569         struct dentry *upper = ovl_dentry_upper(dentry);
 570         int err;
 571
 572         mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
 573         err = -ESTALE;
 574         if (upper->d_parent == upperdir) {
 575                 /* Don't let d_delete() think it can reset d_inode */
 576                 dget(upper);
 577                 if (is_dir)
 578                         err = vfs_rmdir(dir, upper);
 579                 else
 580                         err = vfs_unlink(dir, upper, NULL);
 581                 dput(upper);
 582                 ovl_dentry_version_inc(dentry->d_parent);
 583         }
 584
 585         /*
 586          * Keeping this dentry hashed would mean having to release
 587          * upperpath/lowerpath, which could only be done if we are the
 588          * sole user of this dentry.  Too tricky...  Just unhash for
 589          * now.
 590          */
 591         d_drop(dentry);
 592         mutex_unlock(&dir->i_mutex);
 593
 594         return err;
 595 }
 596
 597 static inline int ovl_check_sticky(struct dentry *dentry)
 598 {
 599         struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
 600         struct inode *inode = ovl_dentry_real(dentry)->d_inode;
 601
 602         if (check_sticky(dir, inode))
 603                 return -EPERM;
 604
 605         return 0;
 606 }
 607
 608 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 609 {
 610         enum ovl_path_type type;
 611         int err;
 612
 613         err = ovl_check_sticky(dentry);
 614         if (err)
 615                 goto out;
 616
 617         err = ovl_want_write(dentry);
 618         if (err)
 619                 goto out;
 620
 621         err = ovl_copy_up(dentry->d_parent);
 622         if (err)
 623                 goto out_drop_write;
 624
 625         type = ovl_path_type(dentry);
 626         if (type == OVL_PATH_PURE_UPPER) {
 627                 err = ovl_remove_upper(dentry, is_dir);
 628         } else {
 629                 const struct cred *old_cred;
 630                 struct cred *override_cred;
 631
 632                 err = -ENOMEM;
 633                 override_cred = prepare_creds();
 634                 if (!override_cred)
 635                         goto out_drop_write;
 636
 637                 /*
 638                  * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
 639                  * CAP_DAC_OVERRIDE for create in workdir, rename
 640                  * CAP_FOWNER for removing whiteout from sticky dir
 641                  * CAP_FSETID for chmod of opaque dir
 642                  * CAP_CHOWN for chown of opaque dir
 643                  */
 644                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
 645                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
 646                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
 647                 cap_raise(override_cred->cap_effective, CAP_FSETID);
 648                 cap_raise(override_cred->cap_effective, CAP_CHOWN);
 649                 old_cred = override_creds(override_cred);
 650
 651                 err = ovl_remove_and_whiteout(dentry, type, is_dir);
 652
 653                 revert_creds(old_cred);
 654                 put_cred(override_cred);
 655         }
 656 out_drop_write:
 657         ovl_drop_write(dentry);
 658 out:
 659         return err;
 660 }
 661
 662 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
 663 {
 664         return ovl_do_remove(dentry, false);
 665 }
 666
 667 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 668 {
 669         return ovl_do_remove(dentry, true);
 670 }
 671
 672 static int ovl_rename2(struct inode *olddir, struct dentry *old,
 673                        struct inode *newdir, struct dentry *new,
 674                        unsigned int flags)
 675 {
 676         int err;
 677         enum ovl_path_type old_type;
 678         enum ovl_path_type new_type;
 679         struct dentry *old_upperdir;
 680         struct dentry *new_upperdir;
 681         struct dentry *olddentry;
 682         struct dentry *newdentry;
 683         struct dentry *trap;
 684         bool old_opaque;
 685         bool new_opaque;
 686         bool new_create = false;
 687         bool cleanup_whiteout = false;
 688         bool overwrite = !(flags & RENAME_EXCHANGE);
 689         bool is_dir = S_ISDIR(old->d_inode->i_mode);
 690         bool new_is_dir = false;
 691         struct dentry *opaquedir = NULL;
 692         const struct cred *old_cred = NULL;
 693         struct cred *override_cred = NULL;
 694
 695         err = -EINVAL;
 696         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
 697                 goto out;
 698
 699         flags &= ~RENAME_NOREPLACE;
 700
 701         err = ovl_check_sticky(old);
 702         if (err)
 703                 goto out;
 704
 705         /* Don't copy up directory trees */
 706         old_type = ovl_path_type(old);
 707         err = -EXDEV;
 708         if ((old_type == OVL_PATH_LOWER || old_type == OVL_PATH_MERGE) && is_dir)
 709                 goto out;
 710
 711         if (new->d_inode) {
 712                 err = ovl_check_sticky(new);
 713                 if (err)
 714                         goto out;
 715
 716                 if (S_ISDIR(new->d_inode->i_mode))
 717                         new_is_dir = true;
 718
 719                 new_type = ovl_path_type(new);
 720                 err = -EXDEV;
 721                 if (!overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir)
 722                         goto out;
 723
 724                 err = 0;
 725                 if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) {
 726                         if (ovl_dentry_lower(old)->d_inode ==
 727                             ovl_dentry_lower(new)->d_inode)
 728                                 goto out;
 729                 }
 730                 if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) {
 731                         if (ovl_dentry_upper(old)->d_inode ==
 732                             ovl_dentry_upper(new)->d_inode)
 733                                 goto out;
 734                 }
 735         } else {
 736                 if (ovl_dentry_is_opaque(new))
 737                         new_type = OVL_PATH_UPPER;
 738                 else
 739                         new_type = OVL_PATH_PURE_UPPER;
 740         }
 741
 742         err = ovl_want_write(old);
 743         if (err)
 744                 goto out;
 745
 746         err = ovl_copy_up(old);
 747         if (err)
 748                 goto out_drop_write;
 749
 750         err = ovl_copy_up(new->d_parent);
 751         if (err)
 752                 goto out_drop_write;
 753         if (!overwrite) {
 754                 err = ovl_copy_up(new);
 755                 if (err)
 756                         goto out_drop_write;
 757         }
 758
 759         old_opaque = old_type != OVL_PATH_PURE_UPPER;
 760         new_opaque = new_type != OVL_PATH_PURE_UPPER;
 761
 762         if (old_opaque || new_opaque) {
 763                 err = -ENOMEM;
 764                 override_cred = prepare_creds();
 765                 if (!override_cred)
 766                         goto out_drop_write;
 767
 768                 /*
 769                  * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
 770                  * CAP_DAC_OVERRIDE for create in workdir
 771                  * CAP_FOWNER for removing whiteout from sticky dir
 772                  * CAP_FSETID for chmod of opaque dir
 773                  * CAP_CHOWN for chown of opaque dir
 774                  */
 775                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
 776                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
 777                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
 778                 cap_raise(override_cred->cap_effective, CAP_FSETID);
 779                 cap_raise(override_cred->cap_effective, CAP_CHOWN);
 780                 old_cred = override_creds(override_cred);
 781         }
 782
 783         if (overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir) {
 784                 opaquedir = ovl_check_empty_and_clear(new, new_type);
 785                 err = PTR_ERR(opaquedir);
 786                 if (IS_ERR(opaquedir)) {
 787                         opaquedir = NULL;
 788                         goto out_revert_creds;
 789                 }
 790         }
 791
 792         if (overwrite) {
 793                 if (old_opaque) {
 794                         if (new->d_inode || !new_opaque) {
 795                                 /* Whiteout source */
 796                                 flags |= RENAME_WHITEOUT;
 797                         } else {
 798                                 /* Switch whiteouts */
 799                                 flags |= RENAME_EXCHANGE;
 800                         }
 801                 } else if (is_dir && !new->d_inode && new_opaque) {
 802                         flags |= RENAME_EXCHANGE;
 803                         cleanup_whiteout = true;
 804                 }
 805         }
 806
 807         old_upperdir = ovl_dentry_upper(old->d_parent);
 808         new_upperdir = ovl_dentry_upper(new->d_parent);
 809
 810         trap = lock_rename(new_upperdir, old_upperdir);
 811
 812         olddentry = ovl_dentry_upper(old);
 813         newdentry = ovl_dentry_upper(new);
 814         if (newdentry) {
 815                 if (opaquedir) {
 816                         newdentry = opaquedir;
 817                         opaquedir = NULL;
 818                 } else {
 819                         dget(newdentry);
 820                 }
 821         } else {
 822                 new_create = true;
 823                 newdentry = lookup_one_len(new->d_name.name, new_upperdir,
 824                                            new->d_name.len);
 825                 err = PTR_ERR(newdentry);
 826                 if (IS_ERR(newdentry))
 827                         goto out_unlock;
 828         }
 829
 830         err = -ESTALE;
 831         if (olddentry->d_parent != old_upperdir)
 832                 goto out_dput;
 833         if (newdentry->d_parent != new_upperdir)
 834                 goto out_dput;
 835         if (olddentry == trap)
 836                 goto out_dput;
 837         if (newdentry == trap)
 838                 goto out_dput;
 839
 840         if (is_dir && !old_opaque && new_opaque) {
 841                 err = ovl_set_opaque(olddentry);
 842                 if (err)
 843                         goto out_dput;
 844         }
 845         if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
 846                 err = ovl_set_opaque(newdentry);
 847                 if (err)
 848                         goto out_dput;
 849         }
 850
 851         if (old_opaque || new_opaque) {
 852                 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
 853                                     new_upperdir->d_inode, newdentry,
 854                                     flags);
 855         } else {
 856                 /* No debug for the plain case */
 857                 BUG_ON(flags & ~RENAME_EXCHANGE);
 858                 err = vfs_rename(old_upperdir->d_inode, olddentry,
 859                                  new_upperdir->d_inode, newdentry,
 860                                  NULL, flags);
 861         }
 862
 863         if (err) {
 864                 if (is_dir && !old_opaque && new_opaque)
 865                         ovl_remove_opaque(olddentry);
 866                 if (!overwrite && new_is_dir && old_opaque && !new_opaque)
 867                         ovl_remove_opaque(newdentry);
 868                 goto out_dput;
 869         }
 870
 871         if (is_dir && old_opaque && !new_opaque)
 872                 ovl_remove_opaque(olddentry);
 873         if (!overwrite && new_is_dir && !old_opaque && new_opaque)
 874                 ovl_remove_opaque(newdentry);
 875
 876         if (old_opaque != new_opaque) {
 877                 ovl_dentry_set_opaque(old, new_opaque);
 878                 if (!overwrite)
 879                         ovl_dentry_set_opaque(new, old_opaque);
 880         }
 881
 882         if (cleanup_whiteout)
 883                 ovl_cleanup(old_upperdir->d_inode, newdentry);
 884
 885         ovl_dentry_version_inc(old->d_parent);
 886         ovl_dentry_version_inc(new->d_parent);
 887
 888 out_dput:
 889         dput(newdentry);
 890 out_unlock:
 891         unlock_rename(new_upperdir, old_upperdir);
 892 out_revert_creds:
 893         if (old_opaque || new_opaque) {
 894                 revert_creds(old_cred);
 895                 put_cred(override_cred);
 896         }
 897 out_drop_write:
 898         ovl_drop_write(old);
 899 out:
 900         dput(opaquedir);
 901         return err;
 902 }
 903
 904 const struct inode_operations ovl_dir_inode_operations = {
 905         .lookup         = ovl_lookup,
 906         .mkdir          = ovl_mkdir,
 907         .symlink        = ovl_symlink,
 908         .unlink         = ovl_unlink,
 909         .rmdir          = ovl_rmdir,
 910         .rename2        = ovl_rename2,
 911         .link           = ovl_link,
 912         .setattr        = ovl_setattr,
 913         .create         = ovl_create,
 914         .mknod          = ovl_mknod,
 915         .permission     = ovl_permission,
 916         .getattr        = ovl_dir_getattr,
 917         .setxattr       = ovl_setxattr,
 918         .getxattr       = ovl_getxattr,
 919         .listxattr      = ovl_listxattr,
 920         .removexattr    = ovl_removexattr,
 921 };