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 (d_is_dir(wdentry))
  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_XATTR_OPAQUE, "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_XATTR_OPAQUE);
 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 (OVL_TYPE_MERGE(type))
 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 {
 289         int err;
 290         struct dentry *ret = NULL;
 291         LIST_HEAD(list);
 292
 293         err = ovl_check_empty_dir(dentry, &list);
 294         if (err)
 295                 ret = ERR_PTR(err);
 296         else {
 297                 /*
 298                  * If no upperdentry then skip clearing whiteouts.
 299                  *
 300                  * Can race with copy-up, since we don't hold the upperdir
 301                  * mutex.  Doesn't matter, since copy-up can't create a
 302                  * non-empty directory from an empty one.
 303                  */
 304                 if (ovl_dentry_upper(dentry))
 305                         ret = ovl_clear_empty(dentry, &list);
 306         }
 307
 308         ovl_cache_free(&list);
 309
 310         return ret;
 311 }
 312
 313 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 314                                     struct kstat *stat, const char *link,
 315                                     struct dentry *hardlink)
 316 {
 317         struct dentry *workdir = ovl_workdir(dentry);
 318         struct inode *wdir = workdir->d_inode;
 319         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 320         struct inode *udir = upperdir->d_inode;
 321         struct dentry *upper;
 322         struct dentry *newdentry;
 323         int err;
 324
 325         err = ovl_lock_rename_workdir(workdir, upperdir);
 326         if (err)
 327                 goto out;
 328
 329         newdentry = ovl_lookup_temp(workdir, dentry);
 330         err = PTR_ERR(newdentry);
 331         if (IS_ERR(newdentry))
 332                 goto out_unlock;
 333
 334         upper = lookup_one_len(dentry->d_name.name, upperdir,
 335                                dentry->d_name.len);
 336         err = PTR_ERR(upper);
 337         if (IS_ERR(upper))
 338                 goto out_dput;
 339
 340         err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
 341         if (err)
 342                 goto out_dput2;
 343
 344         if (S_ISDIR(stat->mode)) {
 345                 err = ovl_set_opaque(newdentry);
 346                 if (err)
 347                         goto out_cleanup;
 348
 349                 err = ovl_do_rename(wdir, newdentry, udir, upper,
 350                                     RENAME_EXCHANGE);
 351                 if (err)
 352                         goto out_cleanup;
 353
 354                 ovl_cleanup(wdir, upper);
 355         } else {
 356                 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
 357                 if (err)
 358                         goto out_cleanup;
 359         }
 360         ovl_dentry_version_inc(dentry->d_parent);
 361         ovl_dentry_update(dentry, newdentry);
 362         ovl_copyattr(newdentry->d_inode, inode);
 363         d_instantiate(dentry, inode);
 364         newdentry = NULL;
 365 out_dput2:
 366         dput(upper);
 367 out_dput:
 368         dput(newdentry);
 369 out_unlock:
 370         unlock_rename(workdir, upperdir);
 371 out:
 372         return err;
 373
 374 out_cleanup:
 375         ovl_cleanup(wdir, newdentry);
 376         goto out_dput2;
 377 }
 378
 379 static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
 380                               const char *link, struct dentry *hardlink)
 381 {
 382         int err;
 383         struct inode *inode;
 384         struct kstat stat = {
 385                 .mode = mode,
 386                 .rdev = rdev,
 387         };
 388
 389         err = -ENOMEM;
 390         inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
 391         if (!inode)
 392                 goto out;
 393
 394         err = ovl_copy_up(dentry->d_parent);
 395         if (err)
 396                 goto out_iput;
 397
 398         if (!ovl_dentry_is_opaque(dentry)) {
 399                 err = ovl_create_upper(dentry, inode, &stat, link, hardlink);
 400         } else {
 401                 const struct cred *old_cred;
 402                 struct cred *override_cred;
 403
 404                 err = -ENOMEM;
 405                 override_cred = prepare_creds();
 406                 if (!override_cred)
 407                         goto out_iput;
 408
 409                 /*
 410                  * CAP_SYS_ADMIN for setting opaque xattr
 411                  * CAP_DAC_OVERRIDE for create in workdir, rename
 412                  * CAP_FOWNER for removing whiteout from sticky dir
 413                  */
 414                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
 415                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
 416                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
 417                 old_cred = override_creds(override_cred);
 418
 419                 err = ovl_create_over_whiteout(dentry, inode, &stat, link,
 420                                                hardlink);
 421
 422                 revert_creds(old_cred);
 423                 put_cred(override_cred);
 424         }
 425
 426         if (!err)
 427                 inode = NULL;
 428 out_iput:
 429         iput(inode);
 430 out:
 431         return err;
 432 }
 433
 434 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 435                              const char *link)
 436 {
 437         int err;
 438
 439         err = ovl_want_write(dentry);
 440         if (!err) {
 441                 err = ovl_create_or_link(dentry, mode, rdev, link, NULL);
 442                 ovl_drop_write(dentry);
 443         }
 444
 445         return err;
 446 }
 447
 448 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 449                       bool excl)
 450 {
 451         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 452 }
 453
 454 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 455 {
 456         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 457 }
 458
 459 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 460                      dev_t rdev)
 461 {
 462         /* Don't allow creation of "whiteout" on overlay */
 463         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
 464                 return -EPERM;
 465
 466         return ovl_create_object(dentry, mode, rdev, NULL);
 467 }
 468
 469 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
 470                        const char *link)
 471 {
 472         return ovl_create_object(dentry, S_IFLNK, 0, link);
 473 }
 474
 475 static int ovl_link(struct dentry *old, struct inode *newdir,
 476                     struct dentry *new)
 477 {
 478         int err;
 479         struct dentry *upper;
 480
 481         err = ovl_want_write(old);
 482         if (err)
 483                 goto out;
 484
 485         err = ovl_copy_up(old);
 486         if (err)
 487                 goto out_drop_write;
 488
 489         upper = ovl_dentry_upper(old);
 490         err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper);
 491
 492 out_drop_write:
 493         ovl_drop_write(old);
 494 out:
 495         return err;
 496 }
 497
 498 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
 499 {
 500         struct dentry *workdir = ovl_workdir(dentry);
 501         struct inode *wdir = workdir->d_inode;
 502         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 503         struct inode *udir = upperdir->d_inode;
 504         struct dentry *whiteout;
 505         struct dentry *upper;
 506         struct dentry *opaquedir = NULL;
 507         int err;
 508
 509         if (is_dir && OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
 510                 opaquedir = ovl_check_empty_and_clear(dentry);
 511                 err = PTR_ERR(opaquedir);
 512                 if (IS_ERR(opaquedir))
 513                         goto out;
 514         }
 515
 516         err = ovl_lock_rename_workdir(workdir, upperdir);
 517         if (err)
 518                 goto out_dput;
 519
 520         whiteout = ovl_whiteout(workdir, dentry);
 521         err = PTR_ERR(whiteout);
 522         if (IS_ERR(whiteout))
 523                 goto out_unlock;
 524
 525         upper = ovl_dentry_upper(dentry);
 526         if (!upper) {
 527                 upper = lookup_one_len(dentry->d_name.name, upperdir,
 528                                        dentry->d_name.len);
 529                 err = PTR_ERR(upper);
 530                 if (IS_ERR(upper))
 531                         goto kill_whiteout;
 532
 533                 err = ovl_do_rename(wdir, whiteout, udir, upper, 0);
 534                 dput(upper);
 535                 if (err)
 536                         goto kill_whiteout;
 537         } else {
 538                 int flags = 0;
 539
 540                 if (opaquedir)
 541                         upper = opaquedir;
 542                 err = -ESTALE;
 543                 if (upper->d_parent != upperdir)
 544                         goto kill_whiteout;
 545
 546                 if (is_dir)
 547                         flags |= RENAME_EXCHANGE;
 548
 549                 err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
 550                 if (err)
 551                         goto kill_whiteout;
 552
 553                 if (is_dir)
 554                         ovl_cleanup(wdir, upper);
 555         }
 556         ovl_dentry_version_inc(dentry->d_parent);
 557 out_d_drop:
 558         d_drop(dentry);
 559         dput(whiteout);
 560 out_unlock:
 561         unlock_rename(workdir, upperdir);
 562 out_dput:
 563         dput(opaquedir);
 564 out:
 565         return err;
 566
 567 kill_whiteout:
 568         ovl_cleanup(wdir, whiteout);
 569         goto out_d_drop;
 570 }
 571
 572 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
 573 {
 574         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 575         struct inode *dir = upperdir->d_inode;
 576         struct dentry *upper = ovl_dentry_upper(dentry);
 577         int err;
 578
 579         mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
 580         err = -ESTALE;
 581         if (upper->d_parent == upperdir) {
 582                 /* Don't let d_delete() think it can reset d_inode */
 583                 dget(upper);
 584                 if (is_dir)
 585                         err = vfs_rmdir(dir, upper);
 586                 else
 587                         err = vfs_unlink(dir, upper, NULL);
 588                 dput(upper);
 589                 ovl_dentry_version_inc(dentry->d_parent);
 590         }
 591
 592         /*
 593          * Keeping this dentry hashed would mean having to release
 594          * upperpath/lowerpath, which could only be done if we are the
 595          * sole user of this dentry.  Too tricky...  Just unhash for
 596          * now.
 597          */
 598         d_drop(dentry);
 599         mutex_unlock(&dir->i_mutex);
 600
 601         return err;
 602 }
 603
 604 static inline int ovl_check_sticky(struct dentry *dentry)
 605 {
 606         struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
 607         struct inode *inode = ovl_dentry_real(dentry)->d_inode;
 608
 609         if (check_sticky(dir, inode))
 610                 return -EPERM;
 611
 612         return 0;
 613 }
 614
 615 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 616 {
 617         enum ovl_path_type type;
 618         int err;
 619
 620         err = ovl_check_sticky(dentry);
 621         if (err)
 622                 goto out;
 623
 624         err = ovl_want_write(dentry);
 625         if (err)
 626                 goto out;
 627
 628         err = ovl_copy_up(dentry->d_parent);
 629         if (err)
 630                 goto out_drop_write;
 631
 632         type = ovl_path_type(dentry);
 633         if (OVL_TYPE_PURE_UPPER(type)) {
 634                 err = ovl_remove_upper(dentry, is_dir);
 635         } else {
 636                 const struct cred *old_cred;
 637                 struct cred *override_cred;
 638
 639                 err = -ENOMEM;
 640                 override_cred = prepare_creds();
 641                 if (!override_cred)
 642                         goto out_drop_write;
 643
 644                 /*
 645                  * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
 646                  * CAP_DAC_OVERRIDE for create in workdir, rename
 647                  * CAP_FOWNER for removing whiteout from sticky dir
 648                  * CAP_FSETID for chmod of opaque dir
 649                  * CAP_CHOWN for chown of opaque dir
 650                  */
 651                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
 652                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
 653                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
 654                 cap_raise(override_cred->cap_effective, CAP_FSETID);
 655                 cap_raise(override_cred->cap_effective, CAP_CHOWN);
 656                 old_cred = override_creds(override_cred);
 657
 658                 err = ovl_remove_and_whiteout(dentry, is_dir);
 659
 660                 revert_creds(old_cred);
 661                 put_cred(override_cred);
 662         }
 663 out_drop_write:
 664         ovl_drop_write(dentry);
 665 out:
 666         return err;
 667 }
 668
 669 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
 670 {
 671         return ovl_do_remove(dentry, false);
 672 }
 673
 674 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 675 {
 676         return ovl_do_remove(dentry, true);
 677 }
 678
 679 static int ovl_rename2(struct inode *olddir, struct dentry *old,
 680                        struct inode *newdir, struct dentry *new,
 681                        unsigned int flags)
 682 {
 683         int err;
 684         enum ovl_path_type old_type;
 685         enum ovl_path_type new_type;
 686         struct dentry *old_upperdir;
 687         struct dentry *new_upperdir;
 688         struct dentry *olddentry;
 689         struct dentry *newdentry;
 690         struct dentry *trap;
 691         bool old_opaque;
 692         bool new_opaque;
 693         bool new_create = false;
 694         bool cleanup_whiteout = false;
 695         bool overwrite = !(flags & RENAME_EXCHANGE);
 696         bool is_dir = d_is_dir(old);
 697         bool new_is_dir = false;
 698         struct dentry *opaquedir = NULL;
 699         const struct cred *old_cred = NULL;
 700         struct cred *override_cred = NULL;
 701
 702         err = -EINVAL;
 703         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
 704                 goto out;
 705
 706         flags &= ~RENAME_NOREPLACE;
 707
 708         err = ovl_check_sticky(old);
 709         if (err)
 710                 goto out;
 711
 712         /* Don't copy up directory trees */
 713         old_type = ovl_path_type(old);
 714         err = -EXDEV;
 715         if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
 716                 goto out;
 717
 718         if (new->d_inode) {
 719                 err = ovl_check_sticky(new);
 720                 if (err)
 721                         goto out;
 722
 723                 if (d_is_dir(new))
 724                         new_is_dir = true;
 725
 726                 new_type = ovl_path_type(new);
 727                 err = -EXDEV;
 728                 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
 729                         goto out;
 730
 731                 err = 0;
 732                 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
 733                         if (ovl_dentry_lower(old)->d_inode ==
 734                             ovl_dentry_lower(new)->d_inode)
 735                                 goto out;
 736                 }
 737                 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
 738                         if (ovl_dentry_upper(old)->d_inode ==
 739                             ovl_dentry_upper(new)->d_inode)
 740                                 goto out;
 741                 }
 742         } else {
 743                 if (ovl_dentry_is_opaque(new))
 744                         new_type = __OVL_PATH_UPPER;
 745                 else
 746                         new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
 747         }
 748
 749         err = ovl_want_write(old);
 750         if (err)
 751                 goto out;
 752
 753         err = ovl_copy_up(old);
 754         if (err)
 755                 goto out_drop_write;
 756
 757         err = ovl_copy_up(new->d_parent);
 758         if (err)
 759                 goto out_drop_write;
 760         if (!overwrite) {
 761                 err = ovl_copy_up(new);
 762                 if (err)
 763                         goto out_drop_write;
 764         }
 765
 766         old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
 767         new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
 768
 769         if (old_opaque || new_opaque) {
 770                 err = -ENOMEM;
 771                 override_cred = prepare_creds();
 772                 if (!override_cred)
 773                         goto out_drop_write;
 774
 775                 /*
 776                  * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
 777                  * CAP_DAC_OVERRIDE for create in workdir
 778                  * CAP_FOWNER for removing whiteout from sticky dir
 779                  * CAP_FSETID for chmod of opaque dir
 780                  * CAP_CHOWN for chown of opaque dir
 781                  */
 782                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
 783                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
 784                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
 785                 cap_raise(override_cred->cap_effective, CAP_FSETID);
 786                 cap_raise(override_cred->cap_effective, CAP_CHOWN);
 787                 old_cred = override_creds(override_cred);
 788         }
 789
 790         if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
 791                 opaquedir = ovl_check_empty_and_clear(new);
 792                 err = PTR_ERR(opaquedir);
 793                 if (IS_ERR(opaquedir)) {
 794                         opaquedir = NULL;
 795                         goto out_revert_creds;
 796                 }
 797         }
 798
 799         if (overwrite) {
 800                 if (old_opaque) {
 801                         if (new->d_inode || !new_opaque) {
 802                                 /* Whiteout source */
 803                                 flags |= RENAME_WHITEOUT;
 804                         } else {
 805                                 /* Switch whiteouts */
 806                                 flags |= RENAME_EXCHANGE;
 807                         }
 808                 } else if (is_dir && !new->d_inode && new_opaque) {
 809                         flags |= RENAME_EXCHANGE;
 810                         cleanup_whiteout = true;
 811                 }
 812         }
 813
 814         old_upperdir = ovl_dentry_upper(old->d_parent);
 815         new_upperdir = ovl_dentry_upper(new->d_parent);
 816
 817         trap = lock_rename(new_upperdir, old_upperdir);
 818
 819         olddentry = ovl_dentry_upper(old);
 820         newdentry = ovl_dentry_upper(new);
 821         if (newdentry) {
 822                 if (opaquedir) {
 823                         newdentry = opaquedir;
 824                         opaquedir = NULL;
 825                 } else {
 826                         dget(newdentry);
 827                 }
 828         } else {
 829                 new_create = true;
 830                 newdentry = lookup_one_len(new->d_name.name, new_upperdir,
 831                                            new->d_name.len);
 832                 err = PTR_ERR(newdentry);
 833                 if (IS_ERR(newdentry))
 834                         goto out_unlock;
 835         }
 836
 837         err = -ESTALE;
 838         if (olddentry->d_parent != old_upperdir)
 839                 goto out_dput;
 840         if (newdentry->d_parent != new_upperdir)
 841                 goto out_dput;
 842         if (olddentry == trap)
 843                 goto out_dput;
 844         if (newdentry == trap)
 845                 goto out_dput;
 846
 847         if (is_dir && !old_opaque && new_opaque) {
 848                 err = ovl_set_opaque(olddentry);
 849                 if (err)
 850                         goto out_dput;
 851         }
 852         if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
 853                 err = ovl_set_opaque(newdentry);
 854                 if (err)
 855                         goto out_dput;
 856         }
 857
 858         if (old_opaque || new_opaque) {
 859                 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
 860                                     new_upperdir->d_inode, newdentry,
 861                                     flags);
 862         } else {
 863                 /* No debug for the plain case */
 864                 BUG_ON(flags & ~RENAME_EXCHANGE);
 865                 err = vfs_rename(old_upperdir->d_inode, olddentry,
 866                                  new_upperdir->d_inode, newdentry,
 867                                  NULL, flags);
 868         }
 869
 870         if (err) {
 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                 goto out_dput;
 876         }
 877
 878         if (is_dir && old_opaque && !new_opaque)
 879                 ovl_remove_opaque(olddentry);
 880         if (!overwrite && new_is_dir && !old_opaque && new_opaque)
 881                 ovl_remove_opaque(newdentry);
 882
 883         if (old_opaque != new_opaque) {
 884                 ovl_dentry_set_opaque(old, new_opaque);
 885                 if (!overwrite)
 886                         ovl_dentry_set_opaque(new, old_opaque);
 887         }
 888
 889         if (cleanup_whiteout)
 890                 ovl_cleanup(old_upperdir->d_inode, newdentry);
 891
 892         ovl_dentry_version_inc(old->d_parent);
 893         ovl_dentry_version_inc(new->d_parent);
 894
 895 out_dput:
 896         dput(newdentry);
 897 out_unlock:
 898         unlock_rename(new_upperdir, old_upperdir);
 899 out_revert_creds:
 900         if (old_opaque || new_opaque) {
 901                 revert_creds(old_cred);
 902                 put_cred(override_cred);
 903         }
 904 out_drop_write:
 905         ovl_drop_write(old);
 906 out:
 907         dput(opaquedir);
 908         return err;
 909 }
 910
 911 const struct inode_operations ovl_dir_inode_operations = {
 912         .lookup         = ovl_lookup,
 913         .mkdir          = ovl_mkdir,
 914         .symlink        = ovl_symlink,
 915         .unlink         = ovl_unlink,
 916         .rmdir          = ovl_rmdir,
 917         .rename2        = ovl_rename2,
 918         .link           = ovl_link,
 919         .setattr        = ovl_setattr,
 920         .create         = ovl_create,
 921         .mknod          = ovl_mknod,
 922         .permission     = ovl_permission,
 923         .getattr        = ovl_dir_getattr,
 924         .setxattr       = ovl_setxattr,
 925         .getxattr       = ovl_getxattr,
 926         .listxattr      = ovl_listxattr,
 927         .removexattr    = ovl_removexattr,
 928 };