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 <linux/posix_acl.h>
  16 #include <linux/posix_acl_xattr.h>
  17 #include <linux/atomic.h>
  18 #include "overlayfs.h"
  19
  20 void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
  21 {
  22         int err;
  23
  24         dget(wdentry);
  25         if (d_is_dir(wdentry))
  26                 err = ovl_do_rmdir(wdir, wdentry);
  27         else
  28                 err = ovl_do_unlink(wdir, wdentry);
  29         dput(wdentry);
  30
  31         if (err) {
  32                 pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
  33                        wdentry, err);
  34         }
  35 }
  36
  37 struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry)
  38 {
  39         struct dentry *temp;
  40         char name[20];
  41         static atomic_t temp_id = ATOMIC_INIT(0);
  42
  43         /* counter is allowed to wrap, since temp dentries are ephemeral */
  44         snprintf(name, sizeof(name), "#%x", atomic_inc_return(&temp_id));
  45
  46         temp = lookup_one_len(name, workdir, strlen(name));
  47         if (!IS_ERR(temp) && temp->d_inode) {
  48                 pr_err("overlayfs: workdir/%s already exists\n", name);
  49                 dput(temp);
  50                 temp = ERR_PTR(-EIO);
  51         }
  52
  53         return temp;
  54 }
  55
  56 /* caller holds i_mutex on workdir */
  57 static struct dentry *ovl_whiteout(struct dentry *workdir,
  58                                    struct dentry *dentry)
  59 {
  60         int err;
  61         struct dentry *whiteout;
  62         struct inode *wdir = workdir->d_inode;
  63
  64         whiteout = ovl_lookup_temp(workdir, dentry);
  65         if (IS_ERR(whiteout))
  66                 return whiteout;
  67
  68         err = ovl_do_whiteout(wdir, whiteout);
  69         if (err) {
  70                 dput(whiteout);
  71                 whiteout = ERR_PTR(err);
  72         }
  73
  74         return whiteout;
  75 }
  76
  77 int ovl_create_real(struct inode *dir, struct dentry *newdentry,
  78                     struct kstat *stat, const char *link,
  79                     struct dentry *hardlink, bool debug)
  80 {
  81         int err;
  82
  83         if (newdentry->d_inode)
  84                 return -ESTALE;
  85
  86         if (hardlink) {
  87                 err = ovl_do_link(hardlink, dir, newdentry, debug);
  88         } else {
  89                 switch (stat->mode & S_IFMT) {
  90                 case S_IFREG:
  91                         err = ovl_do_create(dir, newdentry, stat->mode, debug);
  92                         break;
  93
  94                 case S_IFDIR:
  95                         err = ovl_do_mkdir(dir, newdentry, stat->mode, debug);
  96                         break;
  97
  98                 case S_IFCHR:
  99                 case S_IFBLK:
 100                 case S_IFIFO:
 101                 case S_IFSOCK:
 102                         err = ovl_do_mknod(dir, newdentry,
 103                                            stat->mode, stat->rdev, debug);
 104                         break;
 105
 106                 case S_IFLNK:
 107                         err = ovl_do_symlink(dir, newdentry, link, debug);
 108                         break;
 109
 110                 default:
 111                         err = -EPERM;
 112                 }
 113         }
 114         if (!err && WARN_ON(!newdentry->d_inode)) {
 115                 /*
 116                  * Not quite sure if non-instantiated dentry is legal or not.
 117                  * VFS doesn't seem to care so check and warn here.
 118                  */
 119                 err = -ENOENT;
 120         }
 121         return err;
 122 }
 123
 124 static int ovl_set_opaque(struct dentry *upperdentry)
 125 {
 126         return ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
 127 }
 128
 129 static void ovl_remove_opaque(struct dentry *upperdentry)
 130 {
 131         int err;
 132
 133         err = ovl_do_removexattr(upperdentry, OVL_XATTR_OPAQUE);
 134         if (err) {
 135                 pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n",
 136                         upperdentry->d_name.name, err);
 137         }
 138 }
 139
 140 static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
 141                          struct kstat *stat)
 142 {
 143         int err;
 144         enum ovl_path_type type;
 145         struct path realpath;
 146         const struct cred *old_cred;
 147
 148         type = ovl_path_real(dentry, &realpath);
 149         old_cred = ovl_override_creds(dentry->d_sb);
 150         err = vfs_getattr(&realpath, stat);
 151         revert_creds(old_cred);
 152         if (err)
 153                 return err;
 154
 155         stat->dev = dentry->d_sb->s_dev;
 156         stat->ino = dentry->d_inode->i_ino;
 157
 158         /*
 159          * It's probably not worth it to count subdirs to get the
 160          * correct link count.  nlink=1 seems to pacify 'find' and
 161          * other utilities.
 162          */
 163         if (OVL_TYPE_MERGE(type))
 164                 stat->nlink = 1;
 165
 166         return 0;
 167 }
 168
 169 /* Common operations required to be done after creation of file on upper */
 170 static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
 171                             struct dentry *newdentry, bool hardlink)
 172 {
 173         ovl_dentry_version_inc(dentry->d_parent);
 174         ovl_dentry_update(dentry, newdentry);
 175         if (!hardlink) {
 176                 ovl_inode_update(inode, d_inode(newdentry));
 177                 ovl_copyattr(newdentry->d_inode, inode);
 178         } else {
 179                 WARN_ON(ovl_inode_real(inode, NULL) != d_inode(newdentry));
 180                 inc_nlink(inode);
 181         }
 182         d_instantiate(dentry, inode);
 183 }
 184
 185 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
 186                             struct kstat *stat, const char *link,
 187                             struct dentry *hardlink)
 188 {
 189         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 190         struct inode *udir = upperdir->d_inode;
 191         struct dentry *newdentry;
 192         int err;
 193
 194         if (!hardlink && !IS_POSIXACL(udir))
 195                 stat->mode &= ~current_umask();
 196
 197         inode_lock_nested(udir, I_MUTEX_PARENT);
 198         newdentry = lookup_one_len(dentry->d_name.name, upperdir,
 199                                    dentry->d_name.len);
 200         err = PTR_ERR(newdentry);
 201         if (IS_ERR(newdentry))
 202                 goto out_unlock;
 203         err = ovl_create_real(udir, newdentry, stat, link, hardlink, false);
 204         if (err)
 205                 goto out_dput;
 206
 207         ovl_instantiate(dentry, inode, newdentry, !!hardlink);
 208         newdentry = NULL;
 209 out_dput:
 210         dput(newdentry);
 211 out_unlock:
 212         inode_unlock(udir);
 213         return err;
 214 }
 215
 216 static int ovl_lock_rename_workdir(struct dentry *workdir,
 217                                    struct dentry *upperdir)
 218 {
 219         /* Workdir should not be the same as upperdir */
 220         if (workdir == upperdir)
 221                 goto err;
 222
 223         /* Workdir should not be subdir of upperdir and vice versa */
 224         if (lock_rename(workdir, upperdir) != NULL)
 225                 goto err_unlock;
 226
 227         return 0;
 228
 229 err_unlock:
 230         unlock_rename(workdir, upperdir);
 231 err:
 232         pr_err("overlayfs: failed to lock workdir+upperdir\n");
 233         return -EIO;
 234 }
 235
 236 static struct dentry *ovl_clear_empty(struct dentry *dentry,
 237                                       struct list_head *list)
 238 {
 239         struct dentry *workdir = ovl_workdir(dentry);
 240         struct inode *wdir = workdir->d_inode;
 241         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 242         struct inode *udir = upperdir->d_inode;
 243         struct path upperpath;
 244         struct dentry *upper;
 245         struct dentry *opaquedir;
 246         struct kstat stat;
 247         int err;
 248
 249         if (WARN_ON(!workdir))
 250                 return ERR_PTR(-EROFS);
 251
 252         err = ovl_lock_rename_workdir(workdir, upperdir);
 253         if (err)
 254                 goto out;
 255
 256         ovl_path_upper(dentry, &upperpath);
 257         err = vfs_getattr(&upperpath, &stat);
 258         if (err)
 259                 goto out_unlock;
 260
 261         err = -ESTALE;
 262         if (!S_ISDIR(stat.mode))
 263                 goto out_unlock;
 264         upper = upperpath.dentry;
 265         if (upper->d_parent->d_inode != udir)
 266                 goto out_unlock;
 267
 268         opaquedir = ovl_lookup_temp(workdir, dentry);
 269         err = PTR_ERR(opaquedir);
 270         if (IS_ERR(opaquedir))
 271                 goto out_unlock;
 272
 273         err = ovl_create_real(wdir, opaquedir, &stat, NULL, NULL, true);
 274         if (err)
 275                 goto out_dput;
 276
 277         err = ovl_copy_xattr(upper, opaquedir);
 278         if (err)
 279                 goto out_cleanup;
 280
 281         err = ovl_set_opaque(opaquedir);
 282         if (err)
 283                 goto out_cleanup;
 284
 285         inode_lock(opaquedir->d_inode);
 286         err = ovl_set_attr(opaquedir, &stat);
 287         inode_unlock(opaquedir->d_inode);
 288         if (err)
 289                 goto out_cleanup;
 290
 291         err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
 292         if (err)
 293                 goto out_cleanup;
 294
 295         ovl_cleanup_whiteouts(upper, list);
 296         ovl_cleanup(wdir, upper);
 297         unlock_rename(workdir, upperdir);
 298
 299         /* dentry's upper doesn't match now, get rid of it */
 300         d_drop(dentry);
 301
 302         return opaquedir;
 303
 304 out_cleanup:
 305         ovl_cleanup(wdir, opaquedir);
 306 out_dput:
 307         dput(opaquedir);
 308 out_unlock:
 309         unlock_rename(workdir, upperdir);
 310 out:
 311         return ERR_PTR(err);
 312 }
 313
 314 static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
 315 {
 316         int err;
 317         struct dentry *ret = NULL;
 318         enum ovl_path_type type = ovl_path_type(dentry);
 319         LIST_HEAD(list);
 320
 321         err = ovl_check_empty_dir(dentry, &list);
 322         if (err) {
 323                 ret = ERR_PTR(err);
 324                 goto out_free;
 325         }
 326
 327         /*
 328          * When removing an empty opaque directory, then it makes no sense to
 329          * replace it with an exact replica of itself.
 330          *
 331          * If no upperdentry then skip clearing whiteouts.
 332          *
 333          * Can race with copy-up, since we don't hold the upperdir mutex.
 334          * Doesn't matter, since copy-up can't create a non-empty directory
 335          * from an empty one.
 336          */
 337         if (OVL_TYPE_UPPER(type) && OVL_TYPE_MERGE(type))
 338                 ret = ovl_clear_empty(dentry, &list);
 339
 340 out_free:
 341         ovl_cache_free(&list);
 342
 343         return ret;
 344 }
 345
 346 static int ovl_set_upper_acl(struct dentry *upperdentry, const char *name,
 347                              const struct posix_acl *acl)
 348 {
 349         void *buffer;
 350         size_t size;
 351         int err;
 352
 353         if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl)
 354                 return 0;
 355
 356         size = posix_acl_to_xattr(NULL, acl, NULL, 0);
 357         buffer = kmalloc(size, GFP_KERNEL);
 358         if (!buffer)
 359                 return -ENOMEM;
 360
 361         size = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
 362         err = size;
 363         if (err < 0)
 364                 goto out_free;
 365
 366         err = vfs_setxattr(upperdentry, name, buffer, size, XATTR_CREATE);
 367 out_free:
 368         kfree(buffer);
 369         return err;
 370 }
 371
 372 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 373                                     struct kstat *stat, const char *link,
 374                                     struct dentry *hardlink)
 375 {
 376         struct dentry *workdir = ovl_workdir(dentry);
 377         struct inode *wdir = workdir->d_inode;
 378         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 379         struct inode *udir = upperdir->d_inode;
 380         struct dentry *upper;
 381         struct dentry *newdentry;
 382         int err;
 383         struct posix_acl *acl, *default_acl;
 384
 385         if (WARN_ON(!workdir))
 386                 return -EROFS;
 387
 388         if (!hardlink) {
 389                 err = posix_acl_create(dentry->d_parent->d_inode,
 390                                        &stat->mode, &default_acl, &acl);
 391                 if (err)
 392                         return err;
 393         }
 394
 395         err = ovl_lock_rename_workdir(workdir, upperdir);
 396         if (err)
 397                 goto out;
 398
 399         newdentry = ovl_lookup_temp(workdir, dentry);
 400         err = PTR_ERR(newdentry);
 401         if (IS_ERR(newdentry))
 402                 goto out_unlock;
 403
 404         upper = lookup_one_len(dentry->d_name.name, upperdir,
 405                                dentry->d_name.len);
 406         err = PTR_ERR(upper);
 407         if (IS_ERR(upper))
 408                 goto out_dput;
 409
 410         err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
 411         if (err)
 412                 goto out_dput2;
 413
 414         /*
 415          * mode could have been mutilated due to umask (e.g. sgid directory)
 416          */
 417         if (!hardlink &&
 418             !S_ISLNK(stat->mode) && newdentry->d_inode->i_mode != stat->mode) {
 419                 struct iattr attr = {
 420                         .ia_valid = ATTR_MODE,
 421                         .ia_mode = stat->mode,
 422                 };
 423                 inode_lock(newdentry->d_inode);
 424                 err = notify_change(newdentry, &attr, NULL);
 425                 inode_unlock(newdentry->d_inode);
 426                 if (err)
 427                         goto out_cleanup;
 428         }
 429         if (!hardlink) {
 430                 err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_ACCESS,
 431                                         acl);
 432                 if (err)
 433                         goto out_cleanup;
 434
 435                 err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_DEFAULT,
 436                                         default_acl);
 437                 if (err)
 438                         goto out_cleanup;
 439         }
 440
 441         if (!hardlink && S_ISDIR(stat->mode)) {
 442                 err = ovl_set_opaque(newdentry);
 443                 if (err)
 444                         goto out_cleanup;
 445
 446                 err = ovl_do_rename(wdir, newdentry, udir, upper,
 447                                     RENAME_EXCHANGE);
 448                 if (err)
 449                         goto out_cleanup;
 450
 451                 ovl_cleanup(wdir, upper);
 452         } else {
 453                 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
 454                 if (err)
 455                         goto out_cleanup;
 456         }
 457         ovl_instantiate(dentry, inode, newdentry, !!hardlink);
 458         newdentry = NULL;
 459 out_dput2:
 460         dput(upper);
 461 out_dput:
 462         dput(newdentry);
 463 out_unlock:
 464         unlock_rename(workdir, upperdir);
 465 out:
 466         if (!hardlink) {
 467                 posix_acl_release(acl);
 468                 posix_acl_release(default_acl);
 469         }
 470         return err;
 471
 472 out_cleanup:
 473         ovl_cleanup(wdir, newdentry);
 474         goto out_dput2;
 475 }
 476
 477 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
 478                               struct kstat *stat, const char *link,
 479                               struct dentry *hardlink)
 480 {
 481         int err;
 482         const struct cred *old_cred;
 483         struct cred *override_cred;
 484
 485         err = ovl_copy_up(dentry->d_parent);
 486         if (err)
 487                 return err;
 488
 489         old_cred = ovl_override_creds(dentry->d_sb);
 490         err = -ENOMEM;
 491         override_cred = prepare_creds();
 492         if (override_cred) {
 493                 override_cred->fsuid = inode->i_uid;
 494                 override_cred->fsgid = inode->i_gid;
 495                 if (!hardlink) {
 496                         err = security_dentry_create_files_as(dentry,
 497                                         stat->mode, &dentry->d_name, old_cred,
 498                                         override_cred);
 499                         if (err) {
 500                                 put_cred(override_cred);
 501                                 goto out_revert_creds;
 502                         }
 503                 }
 504                 put_cred(override_creds(override_cred));
 505                 put_cred(override_cred);
 506
 507                 if (!ovl_dentry_is_opaque(dentry))
 508                         err = ovl_create_upper(dentry, inode, stat, link,
 509                                                 hardlink);
 510                 else
 511                         err = ovl_create_over_whiteout(dentry, inode, stat,
 512                                                         link, hardlink);
 513         }
 514 out_revert_creds:
 515         revert_creds(old_cred);
 516         if (!err) {
 517                 struct inode *realinode = d_inode(ovl_dentry_upper(dentry));
 518
 519                 WARN_ON(inode->i_mode != realinode->i_mode);
 520                 WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
 521                 WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
 522         }
 523         return err;
 524 }
 525
 526 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 527                              const char *link)
 528 {
 529         int err;
 530         struct inode *inode;
 531         struct kstat stat = {
 532                 .rdev = rdev,
 533         };
 534
 535         err = ovl_want_write(dentry);
 536         if (err)
 537                 goto out;
 538
 539         err = -ENOMEM;
 540         inode = ovl_new_inode(dentry->d_sb, mode);
 541         if (!inode)
 542                 goto out_drop_write;
 543
 544         inode_init_owner(inode, dentry->d_parent->d_inode, mode);
 545         stat.mode = inode->i_mode;
 546
 547         err = ovl_create_or_link(dentry, inode, &stat, link, NULL);
 548         if (err)
 549                 iput(inode);
 550
 551 out_drop_write:
 552         ovl_drop_write(dentry);
 553 out:
 554         return err;
 555 }
 556
 557 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 558                       bool excl)
 559 {
 560         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 561 }
 562
 563 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 564 {
 565         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 566 }
 567
 568 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 569                      dev_t rdev)
 570 {
 571         /* Don't allow creation of "whiteout" on overlay */
 572         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
 573                 return -EPERM;
 574
 575         return ovl_create_object(dentry, mode, rdev, NULL);
 576 }
 577
 578 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
 579                        const char *link)
 580 {
 581         return ovl_create_object(dentry, S_IFLNK, 0, link);
 582 }
 583
 584 static int ovl_link(struct dentry *old, struct inode *newdir,
 585                     struct dentry *new)
 586 {
 587         int err;
 588         struct inode *inode;
 589
 590         err = ovl_want_write(old);
 591         if (err)
 592                 goto out;
 593
 594         err = ovl_copy_up(old);
 595         if (err)
 596                 goto out_drop_write;
 597
 598         inode = d_inode(old);
 599         ihold(inode);
 600
 601         err = ovl_create_or_link(new, inode, NULL, NULL, ovl_dentry_upper(old));
 602         if (err)
 603                 iput(inode);
 604
 605 out_drop_write:
 606         ovl_drop_write(old);
 607 out:
 608         return err;
 609 }
 610
 611 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
 612 {
 613         struct dentry *workdir = ovl_workdir(dentry);
 614         struct inode *wdir = workdir->d_inode;
 615         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 616         struct inode *udir = upperdir->d_inode;
 617         struct dentry *whiteout;
 618         struct dentry *upper;
 619         struct dentry *opaquedir = NULL;
 620         int err;
 621         int flags = 0;
 622
 623         if (WARN_ON(!workdir))
 624                 return -EROFS;
 625
 626         if (is_dir) {
 627                 opaquedir = ovl_check_empty_and_clear(dentry);
 628                 err = PTR_ERR(opaquedir);
 629                 if (IS_ERR(opaquedir))
 630                         goto out;
 631         }
 632
 633         err = ovl_lock_rename_workdir(workdir, upperdir);
 634         if (err)
 635                 goto out_dput;
 636
 637         upper = lookup_one_len(dentry->d_name.name, upperdir,
 638                                dentry->d_name.len);
 639         err = PTR_ERR(upper);
 640         if (IS_ERR(upper))
 641                 goto out_unlock;
 642
 643         err = -ESTALE;
 644         if ((opaquedir && upper != opaquedir) ||
 645             (!opaquedir && ovl_dentry_upper(dentry) &&
 646              upper != ovl_dentry_upper(dentry))) {
 647                 goto out_dput_upper;
 648         }
 649
 650         whiteout = ovl_whiteout(workdir, dentry);
 651         err = PTR_ERR(whiteout);
 652         if (IS_ERR(whiteout))
 653                 goto out_dput_upper;
 654
 655         if (d_is_dir(upper))
 656                 flags = RENAME_EXCHANGE;
 657
 658         err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
 659         if (err)
 660                 goto kill_whiteout;
 661         if (flags)
 662                 ovl_cleanup(wdir, upper);
 663
 664         ovl_dentry_version_inc(dentry->d_parent);
 665 out_d_drop:
 666         d_drop(dentry);
 667         dput(whiteout);
 668 out_dput_upper:
 669         dput(upper);
 670 out_unlock:
 671         unlock_rename(workdir, upperdir);
 672 out_dput:
 673         dput(opaquedir);
 674 out:
 675         return err;
 676
 677 kill_whiteout:
 678         ovl_cleanup(wdir, whiteout);
 679         goto out_d_drop;
 680 }
 681
 682 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
 683 {
 684         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 685         struct inode *dir = upperdir->d_inode;
 686         struct dentry *upper;
 687         int err;
 688
 689         inode_lock_nested(dir, I_MUTEX_PARENT);
 690         upper = lookup_one_len(dentry->d_name.name, upperdir,
 691                                dentry->d_name.len);
 692         err = PTR_ERR(upper);
 693         if (IS_ERR(upper))
 694                 goto out_unlock;
 695
 696         err = -ESTALE;
 697         if (upper == ovl_dentry_upper(dentry)) {
 698                 if (is_dir)
 699                         err = vfs_rmdir(dir, upper);
 700                 else
 701                         err = vfs_unlink(dir, upper, NULL);
 702                 ovl_dentry_version_inc(dentry->d_parent);
 703         }
 704         dput(upper);
 705
 706         /*
 707          * Keeping this dentry hashed would mean having to release
 708          * upperpath/lowerpath, which could only be done if we are the
 709          * sole user of this dentry.  Too tricky...  Just unhash for
 710          * now.
 711          */
 712         if (!err)
 713                 d_drop(dentry);
 714 out_unlock:
 715         inode_unlock(dir);
 716
 717         return err;
 718 }
 719
 720 static inline int ovl_check_sticky(struct dentry *dentry)
 721 {
 722         struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
 723         struct inode *inode = ovl_dentry_real(dentry)->d_inode;
 724
 725         if (check_sticky(dir, inode))
 726                 return -EPERM;
 727
 728         return 0;
 729 }
 730
 731 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 732 {
 733         enum ovl_path_type type;
 734         int err;
 735         const struct cred *old_cred;
 736
 737
 738         err = ovl_check_sticky(dentry);
 739         if (err)
 740                 goto out;
 741
 742         err = ovl_want_write(dentry);
 743         if (err)
 744                 goto out;
 745
 746         err = ovl_copy_up(dentry->d_parent);
 747         if (err)
 748                 goto out_drop_write;
 749
 750         type = ovl_path_type(dentry);
 751
 752         old_cred = ovl_override_creds(dentry->d_sb);
 753         if (OVL_TYPE_PURE_UPPER(type))
 754                 err = ovl_remove_upper(dentry, is_dir);
 755         else
 756                 err = ovl_remove_and_whiteout(dentry, is_dir);
 757         revert_creds(old_cred);
 758         if (!err) {
 759                 if (is_dir)
 760                         clear_nlink(dentry->d_inode);
 761                 else
 762                         drop_nlink(dentry->d_inode);
 763         }
 764 out_drop_write:
 765         ovl_drop_write(dentry);
 766 out:
 767         return err;
 768 }
 769
 770 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
 771 {
 772         return ovl_do_remove(dentry, false);
 773 }
 774
 775 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 776 {
 777         return ovl_do_remove(dentry, true);
 778 }
 779
 780 static int ovl_rename2(struct inode *olddir, struct dentry *old,
 781                        struct inode *newdir, struct dentry *new,
 782                        unsigned int flags)
 783 {
 784         int err;
 785         enum ovl_path_type old_type;
 786         enum ovl_path_type new_type;
 787         struct dentry *old_upperdir;
 788         struct dentry *new_upperdir;
 789         struct dentry *olddentry;
 790         struct dentry *newdentry;
 791         struct dentry *trap;
 792         bool old_opaque;
 793         bool new_opaque;
 794         bool cleanup_whiteout = false;
 795         bool overwrite = !(flags & RENAME_EXCHANGE);
 796         bool is_dir = d_is_dir(old);
 797         bool new_is_dir = false;
 798         struct dentry *opaquedir = NULL;
 799         const struct cred *old_cred = NULL;
 800
 801         err = -EINVAL;
 802         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
 803                 goto out;
 804
 805         flags &= ~RENAME_NOREPLACE;
 806
 807         err = ovl_check_sticky(old);
 808         if (err)
 809                 goto out;
 810
 811         /* Don't copy up directory trees */
 812         old_type = ovl_path_type(old);
 813         err = -EXDEV;
 814         if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
 815                 goto out;
 816
 817         if (new->d_inode) {
 818                 err = ovl_check_sticky(new);
 819                 if (err)
 820                         goto out;
 821
 822                 if (d_is_dir(new))
 823                         new_is_dir = true;
 824
 825                 new_type = ovl_path_type(new);
 826                 err = -EXDEV;
 827                 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
 828                         goto out;
 829
 830                 err = 0;
 831                 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
 832                         if (ovl_dentry_lower(old)->d_inode ==
 833                             ovl_dentry_lower(new)->d_inode)
 834                                 goto out;
 835                 }
 836                 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
 837                         if (ovl_dentry_upper(old)->d_inode ==
 838                             ovl_dentry_upper(new)->d_inode)
 839                                 goto out;
 840                 }
 841         } else {
 842                 if (ovl_dentry_is_opaque(new))
 843                         new_type = __OVL_PATH_UPPER;
 844                 else
 845                         new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
 846         }
 847
 848         err = ovl_want_write(old);
 849         if (err)
 850                 goto out;
 851
 852         err = ovl_copy_up(old);
 853         if (err)
 854                 goto out_drop_write;
 855
 856         err = ovl_copy_up(new->d_parent);
 857         if (err)
 858                 goto out_drop_write;
 859         if (!overwrite) {
 860                 err = ovl_copy_up(new);
 861                 if (err)
 862                         goto out_drop_write;
 863         }
 864
 865         old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
 866         new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
 867
 868         old_cred = ovl_override_creds(old->d_sb);
 869
 870         if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
 871                 opaquedir = ovl_check_empty_and_clear(new);
 872                 err = PTR_ERR(opaquedir);
 873                 if (IS_ERR(opaquedir)) {
 874                         opaquedir = NULL;
 875                         goto out_revert_creds;
 876                 }
 877         }
 878
 879         if (overwrite) {
 880                 if (old_opaque) {
 881                         if (new->d_inode || !new_opaque) {
 882                                 /* Whiteout source */
 883                                 flags |= RENAME_WHITEOUT;
 884                         } else {
 885                                 /* Switch whiteouts */
 886                                 flags |= RENAME_EXCHANGE;
 887                         }
 888                 } else if (is_dir && !new->d_inode && new_opaque) {
 889                         flags |= RENAME_EXCHANGE;
 890                         cleanup_whiteout = true;
 891                 }
 892         }
 893
 894         old_upperdir = ovl_dentry_upper(old->d_parent);
 895         new_upperdir = ovl_dentry_upper(new->d_parent);
 896
 897         trap = lock_rename(new_upperdir, old_upperdir);
 898
 899
 900         olddentry = lookup_one_len(old->d_name.name, old_upperdir,
 901                                    old->d_name.len);
 902         err = PTR_ERR(olddentry);
 903         if (IS_ERR(olddentry))
 904                 goto out_unlock;
 905
 906         err = -ESTALE;
 907         if (olddentry != ovl_dentry_upper(old))
 908                 goto out_dput_old;
 909
 910         newdentry = lookup_one_len(new->d_name.name, new_upperdir,
 911                                    new->d_name.len);
 912         err = PTR_ERR(newdentry);
 913         if (IS_ERR(newdentry))
 914                 goto out_dput_old;
 915
 916         err = -ESTALE;
 917         if (ovl_dentry_upper(new)) {
 918                 if (opaquedir) {
 919                         if (newdentry != opaquedir)
 920                                 goto out_dput;
 921                 } else {
 922                         if (newdentry != ovl_dentry_upper(new))
 923                                 goto out_dput;
 924                 }
 925         } else {
 926                 if (!d_is_negative(newdentry) &&
 927                     (!new_opaque || !ovl_is_whiteout(newdentry)))
 928                         goto out_dput;
 929         }
 930
 931         if (olddentry == trap)
 932                 goto out_dput;
 933         if (newdentry == trap)
 934                 goto out_dput;
 935
 936         if (is_dir && !old_opaque && new_opaque) {
 937                 err = ovl_set_opaque(olddentry);
 938                 if (err)
 939                         goto out_dput;
 940         }
 941         if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
 942                 err = ovl_set_opaque(newdentry);
 943                 if (err)
 944                         goto out_dput;
 945         }
 946
 947         if (old_opaque || new_opaque) {
 948                 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
 949                                     new_upperdir->d_inode, newdentry,
 950                                     flags);
 951         } else {
 952                 /* No debug for the plain case */
 953                 BUG_ON(flags & ~RENAME_EXCHANGE);
 954                 err = vfs_rename(old_upperdir->d_inode, olddentry,
 955                                  new_upperdir->d_inode, newdentry,
 956                                  NULL, flags);
 957         }
 958
 959         if (err) {
 960                 if (is_dir && !old_opaque && new_opaque)
 961                         ovl_remove_opaque(olddentry);
 962                 if (!overwrite && new_is_dir && old_opaque && !new_opaque)
 963                         ovl_remove_opaque(newdentry);
 964                 goto out_dput;
 965         }
 966
 967         if (is_dir && old_opaque && !new_opaque)
 968                 ovl_remove_opaque(olddentry);
 969         if (!overwrite && new_is_dir && !old_opaque && new_opaque)
 970                 ovl_remove_opaque(newdentry);
 971
 972         /*
 973          * Old dentry now lives in different location. Dentries in
 974          * lowerstack are stale. We cannot drop them here because
 975          * access to them is lockless. This could be only pure upper
 976          * or opaque directory - numlower is zero. Or upper non-dir
 977          * entry - its pureness is tracked by flag opaque.
 978          */
 979         if (old_opaque != new_opaque) {
 980                 ovl_dentry_set_opaque(old, new_opaque);
 981                 if (!overwrite)
 982                         ovl_dentry_set_opaque(new, old_opaque);
 983         }
 984
 985         if (cleanup_whiteout)
 986                 ovl_cleanup(old_upperdir->d_inode, newdentry);
 987
 988         ovl_dentry_version_inc(old->d_parent);
 989         ovl_dentry_version_inc(new->d_parent);
 990
 991 out_dput:
 992         dput(newdentry);
 993 out_dput_old:
 994         dput(olddentry);
 995 out_unlock:
 996         unlock_rename(new_upperdir, old_upperdir);
 997 out_revert_creds:
 998         revert_creds(old_cred);
 999 out_drop_write:
1000         ovl_drop_write(old);
1001 out:
1002         dput(opaquedir);
1003         return err;
1004 }
1005
1006 const struct inode_operations ovl_dir_inode_operations = {
1007         .lookup         = ovl_lookup,
1008         .mkdir          = ovl_mkdir,
1009         .symlink        = ovl_symlink,
1010         .unlink         = ovl_unlink,
1011         .rmdir          = ovl_rmdir,
1012         .rename         = ovl_rename2,
1013         .link           = ovl_link,
1014         .setattr        = ovl_setattr,
1015         .create         = ovl_create,
1016         .mknod          = ovl_mknod,
1017         .permission     = ovl_permission,
1018         .getattr        = ovl_dir_getattr,
1019         .listxattr      = ovl_listxattr,
1020         .get_acl        = ovl_get_acl,
1021         .update_time    = ovl_update_time,
1022 };