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/module.h>
  16 #include <linux/posix_acl.h>
  17 #include <linux/posix_acl_xattr.h>
  18 #include <linux/atomic.h>
  19 #include <linux/ratelimit.h>
  20 #include "overlayfs.h"
  21
  22 static unsigned short ovl_redirect_max = 256;
  23 module_param_named(redirect_max, ovl_redirect_max, ushort, 0644);
  24 MODULE_PARM_DESC(ovl_redirect_max,
  25                  "Maximum length of absolute redirect xattr value");
  26
  27 int ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
  28 {
  29         int err;
  30
  31         dget(wdentry);
  32         if (d_is_dir(wdentry))
  33                 err = ovl_do_rmdir(wdir, wdentry);
  34         else
  35                 err = ovl_do_unlink(wdir, wdentry);
  36         dput(wdentry);
  37
  38         if (err) {
  39                 pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
  40                        wdentry, err);
  41         }
  42
  43         return err;
  44 }
  45
  46 struct dentry *ovl_lookup_temp(struct dentry *workdir)
  47 {
  48         struct dentry *temp;
  49         char name[20];
  50         static atomic_t temp_id = ATOMIC_INIT(0);
  51
  52         /* counter is allowed to wrap, since temp dentries are ephemeral */
  53         snprintf(name, sizeof(name), "#%x", atomic_inc_return(&temp_id));
  54
  55         temp = lookup_one_len(name, workdir, strlen(name));
  56         if (!IS_ERR(temp) && temp->d_inode) {
  57                 pr_err("overlayfs: workdir/%s already exists\n", name);
  58                 dput(temp);
  59                 temp = ERR_PTR(-EIO);
  60         }
  61
  62         return temp;
  63 }
  64
  65 /* caller holds i_mutex on workdir */
  66 static struct dentry *ovl_whiteout(struct dentry *workdir)
  67 {
  68         int err;
  69         struct dentry *whiteout;
  70         struct inode *wdir = workdir->d_inode;
  71
  72         whiteout = ovl_lookup_temp(workdir);
  73         if (IS_ERR(whiteout))
  74                 return whiteout;
  75
  76         err = ovl_do_whiteout(wdir, whiteout);
  77         if (err) {
  78                 dput(whiteout);
  79                 whiteout = ERR_PTR(err);
  80         }
  81
  82         return whiteout;
  83 }
  84
  85 /* Caller must hold i_mutex on both workdir and dir */
  86 int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
  87                              struct dentry *dentry)
  88 {
  89         struct inode *wdir = workdir->d_inode;
  90         struct dentry *whiteout;
  91         int err;
  92         int flags = 0;
  93
  94         whiteout = ovl_whiteout(workdir);
  95         err = PTR_ERR(whiteout);
  96         if (IS_ERR(whiteout))
  97                 return err;
  98
  99         if (d_is_dir(dentry))
 100                 flags = RENAME_EXCHANGE;
 101
 102         err = ovl_do_rename(wdir, whiteout, dir, dentry, flags);
 103         if (err)
 104                 goto kill_whiteout;
 105         if (flags)
 106                 ovl_cleanup(wdir, dentry);
 107
 108 out:
 109         dput(whiteout);
 110         return err;
 111
 112 kill_whiteout:
 113         ovl_cleanup(wdir, whiteout);
 114         goto out;
 115 }
 116
 117 struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry,
 118                                struct ovl_cattr *attr)
 119 {
 120         int err;
 121
 122         if (IS_ERR(newdentry))
 123                 return newdentry;
 124
 125         err = -ESTALE;
 126         if (newdentry->d_inode)
 127                 goto out;
 128
 129         if (attr->hardlink) {
 130                 err = ovl_do_link(attr->hardlink, dir, newdentry);
 131         } else {
 132                 switch (attr->mode & S_IFMT) {
 133                 case S_IFREG:
 134                         err = ovl_do_create(dir, newdentry, attr->mode);
 135                         break;
 136
 137                 case S_IFDIR:
 138                         err = ovl_do_mkdir(dir, newdentry, attr->mode);
 139                         break;
 140
 141                 case S_IFCHR:
 142                 case S_IFBLK:
 143                 case S_IFIFO:
 144                 case S_IFSOCK:
 145                         err = ovl_do_mknod(dir, newdentry, attr->mode,
 146                                            attr->rdev);
 147                         break;
 148
 149                 case S_IFLNK:
 150                         err = ovl_do_symlink(dir, newdentry, attr->link);
 151                         break;
 152
 153                 default:
 154                         err = -EPERM;
 155                 }
 156         }
 157         if (!err && WARN_ON(!newdentry->d_inode)) {
 158                 /*
 159                  * Not quite sure if non-instantiated dentry is legal or not.
 160                  * VFS doesn't seem to care so check and warn here.
 161                  */
 162                 err = -ENOENT;
 163         }
 164 out:
 165         if (err) {
 166                 dput(newdentry);
 167                 return ERR_PTR(err);
 168         }
 169         return newdentry;
 170 }
 171
 172 static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper,
 173                                int xerr)
 174 {
 175         int err;
 176
 177         err = ovl_check_setxattr(dentry, upper, OVL_XATTR_OPAQUE, "y", 1, xerr);
 178         if (!err)
 179                 ovl_dentry_set_opaque(dentry);
 180
 181         return err;
 182 }
 183
 184 static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
 185 {
 186         /*
 187          * Fail with -EIO when trying to create opaque dir and upper doesn't
 188          * support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to
 189          * return a specific error for noxattr case.
 190          */
 191         return ovl_set_opaque_xerr(dentry, upperdentry, -EIO);
 192 }
 193
 194 /* Common operations required to be done after creation of file on upper */
 195 static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
 196                             struct dentry *newdentry, bool hardlink)
 197 {
 198         ovl_dentry_version_inc(dentry->d_parent, false);
 199         ovl_dentry_set_upper_alias(dentry);
 200         if (!hardlink) {
 201                 ovl_inode_update(inode, newdentry);
 202                 ovl_copyattr(newdentry->d_inode, inode);
 203         } else {
 204                 WARN_ON(ovl_inode_real(inode) != d_inode(newdentry));
 205                 dput(newdentry);
 206                 inc_nlink(inode);
 207         }
 208         d_instantiate(dentry, inode);
 209         /* Force lookup of new upper hardlink to find its lower */
 210         if (hardlink)
 211                 d_drop(dentry);
 212 }
 213
 214 static bool ovl_type_merge(struct dentry *dentry)
 215 {
 216         return OVL_TYPE_MERGE(ovl_path_type(dentry));
 217 }
 218
 219 static bool ovl_type_origin(struct dentry *dentry)
 220 {
 221         return OVL_TYPE_ORIGIN(ovl_path_type(dentry));
 222 }
 223
 224 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
 225                             struct ovl_cattr *attr)
 226 {
 227         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 228         struct inode *udir = upperdir->d_inode;
 229         struct dentry *newdentry;
 230         int err;
 231
 232         if (!attr->hardlink && !IS_POSIXACL(udir))
 233                 attr->mode &= ~current_umask();
 234
 235         inode_lock_nested(udir, I_MUTEX_PARENT);
 236         newdentry = ovl_create_real(udir,
 237                                     lookup_one_len(dentry->d_name.name,
 238                                                    upperdir,
 239                                                    dentry->d_name.len),
 240                                     attr);
 241         err = PTR_ERR(newdentry);
 242         if (IS_ERR(newdentry))
 243                 goto out_unlock;
 244
 245         if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry)) {
 246                 /* Setting opaque here is just an optimization, allow to fail */
 247                 ovl_set_opaque(dentry, newdentry);
 248         }
 249
 250         ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink);
 251         err = 0;
 252 out_unlock:
 253         inode_unlock(udir);
 254         return err;
 255 }
 256
 257 static struct dentry *ovl_clear_empty(struct dentry *dentry,
 258                                       struct list_head *list)
 259 {
 260         struct dentry *workdir = ovl_workdir(dentry);
 261         struct inode *wdir = workdir->d_inode;
 262         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 263         struct inode *udir = upperdir->d_inode;
 264         struct path upperpath;
 265         struct dentry *upper;
 266         struct dentry *opaquedir;
 267         struct kstat stat;
 268         int err;
 269
 270         if (WARN_ON(!workdir))
 271                 return ERR_PTR(-EROFS);
 272
 273         err = ovl_lock_rename_workdir(workdir, upperdir);
 274         if (err)
 275                 goto out;
 276
 277         ovl_path_upper(dentry, &upperpath);
 278         err = vfs_getattr(&upperpath, &stat,
 279                           STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
 280         if (err)
 281                 goto out_unlock;
 282
 283         err = -ESTALE;
 284         if (!S_ISDIR(stat.mode))
 285                 goto out_unlock;
 286         upper = upperpath.dentry;
 287         if (upper->d_parent->d_inode != udir)
 288                 goto out_unlock;
 289
 290         opaquedir = ovl_create_real(wdir, ovl_lookup_temp(workdir),
 291                                     OVL_CATTR(stat.mode));
 292         err = PTR_ERR(opaquedir);
 293         if (IS_ERR(opaquedir))
 294                 goto out_unlock;
 295
 296         err = ovl_copy_xattr(upper, opaquedir);
 297         if (err)
 298                 goto out_cleanup;
 299
 300         err = ovl_set_opaque(dentry, opaquedir);
 301         if (err)
 302                 goto out_cleanup;
 303
 304         inode_lock(opaquedir->d_inode);
 305         err = ovl_set_attr(opaquedir, &stat);
 306         inode_unlock(opaquedir->d_inode);
 307         if (err)
 308                 goto out_cleanup;
 309
 310         err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
 311         if (err)
 312                 goto out_cleanup;
 313
 314         ovl_cleanup_whiteouts(upper, list);
 315         ovl_cleanup(wdir, upper);
 316         unlock_rename(workdir, upperdir);
 317
 318         /* dentry's upper doesn't match now, get rid of it */
 319         d_drop(dentry);
 320
 321         return opaquedir;
 322
 323 out_cleanup:
 324         ovl_cleanup(wdir, opaquedir);
 325         dput(opaquedir);
 326 out_unlock:
 327         unlock_rename(workdir, upperdir);
 328 out:
 329         return ERR_PTR(err);
 330 }
 331
 332 static int ovl_set_upper_acl(struct dentry *upperdentry, const char *name,
 333                              const struct posix_acl *acl)
 334 {
 335         void *buffer;
 336         size_t size;
 337         int err;
 338
 339         if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl)
 340                 return 0;
 341
 342         size = posix_acl_to_xattr(NULL, acl, NULL, 0);
 343         buffer = kmalloc(size, GFP_KERNEL);
 344         if (!buffer)
 345                 return -ENOMEM;
 346
 347         size = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
 348         err = size;
 349         if (err < 0)
 350                 goto out_free;
 351
 352         err = vfs_setxattr(upperdentry, name, buffer, size, XATTR_CREATE);
 353 out_free:
 354         kfree(buffer);
 355         return err;
 356 }
 357
 358 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 359                                     struct ovl_cattr *cattr)
 360 {
 361         struct dentry *workdir = ovl_workdir(dentry);
 362         struct inode *wdir = workdir->d_inode;
 363         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 364         struct inode *udir = upperdir->d_inode;
 365         struct dentry *upper;
 366         struct dentry *newdentry;
 367         int err;
 368         struct posix_acl *acl, *default_acl;
 369         bool hardlink = !!cattr->hardlink;
 370
 371         if (WARN_ON(!workdir))
 372                 return -EROFS;
 373
 374         if (!hardlink) {
 375                 err = posix_acl_create(dentry->d_parent->d_inode,
 376                                        &cattr->mode, &default_acl, &acl);
 377                 if (err)
 378                         return err;
 379         }
 380
 381         err = ovl_lock_rename_workdir(workdir, upperdir);
 382         if (err)
 383                 goto out;
 384
 385         upper = lookup_one_len(dentry->d_name.name, upperdir,
 386                                dentry->d_name.len);
 387         err = PTR_ERR(upper);
 388         if (IS_ERR(upper))
 389                 goto out_unlock;
 390
 391         newdentry = ovl_create_real(wdir, ovl_lookup_temp(workdir), cattr);
 392         err = PTR_ERR(newdentry);
 393         if (IS_ERR(newdentry))
 394                 goto out_dput;
 395
 396         /*
 397          * mode could have been mutilated due to umask (e.g. sgid directory)
 398          */
 399         if (!hardlink &&
 400             !S_ISLNK(cattr->mode) &&
 401             newdentry->d_inode->i_mode != cattr->mode) {
 402                 struct iattr attr = {
 403                         .ia_valid = ATTR_MODE,
 404                         .ia_mode = cattr->mode,
 405                 };
 406                 inode_lock(newdentry->d_inode);
 407                 err = notify_change(newdentry, &attr, NULL);
 408                 inode_unlock(newdentry->d_inode);
 409                 if (err)
 410                         goto out_cleanup;
 411         }
 412         if (!hardlink) {
 413                 err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_ACCESS,
 414                                         acl);
 415                 if (err)
 416                         goto out_cleanup;
 417
 418                 err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_DEFAULT,
 419                                         default_acl);
 420                 if (err)
 421                         goto out_cleanup;
 422         }
 423
 424         if (!hardlink && S_ISDIR(cattr->mode)) {
 425                 err = ovl_set_opaque(dentry, newdentry);
 426                 if (err)
 427                         goto out_cleanup;
 428
 429                 err = ovl_do_rename(wdir, newdentry, udir, upper,
 430                                     RENAME_EXCHANGE);
 431                 if (err)
 432                         goto out_cleanup;
 433
 434                 ovl_cleanup(wdir, upper);
 435         } else {
 436                 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
 437                 if (err)
 438                         goto out_cleanup;
 439         }
 440         ovl_instantiate(dentry, inode, newdentry, hardlink);
 441         err = 0;
 442 out_dput:
 443         dput(upper);
 444 out_unlock:
 445         unlock_rename(workdir, upperdir);
 446 out:
 447         if (!hardlink) {
 448                 posix_acl_release(acl);
 449                 posix_acl_release(default_acl);
 450         }
 451         return err;
 452
 453 out_cleanup:
 454         ovl_cleanup(wdir, newdentry);
 455         dput(newdentry);
 456         goto out_dput;
 457 }
 458
 459 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
 460                               struct ovl_cattr *attr, bool origin)
 461 {
 462         int err;
 463         const struct cred *old_cred;
 464         struct cred *override_cred;
 465         struct dentry *parent = dentry->d_parent;
 466
 467         err = ovl_copy_up(parent);
 468         if (err)
 469                 return err;
 470
 471         old_cred = ovl_override_creds(dentry->d_sb);
 472
 473         /*
 474          * When linking a file with copy up origin into a new parent, mark the
 475          * new parent dir "impure".
 476          */
 477         if (origin) {
 478                 err = ovl_set_impure(parent, ovl_dentry_upper(parent));
 479                 if (err)
 480                         goto out_revert_creds;
 481         }
 482
 483         err = -ENOMEM;
 484         override_cred = prepare_creds();
 485         if (override_cred) {
 486                 override_cred->fsuid = inode->i_uid;
 487                 override_cred->fsgid = inode->i_gid;
 488                 if (!attr->hardlink) {
 489                         err = security_dentry_create_files_as(dentry,
 490                                         attr->mode, &dentry->d_name, old_cred,
 491                                         override_cred);
 492                         if (err) {
 493                                 put_cred(override_cred);
 494                                 goto out_revert_creds;
 495                         }
 496                 }
 497                 put_cred(override_creds(override_cred));
 498                 put_cred(override_cred);
 499
 500                 if (!ovl_dentry_is_whiteout(dentry))
 501                         err = ovl_create_upper(dentry, inode, attr);
 502                 else
 503                         err = ovl_create_over_whiteout(dentry, inode, attr);
 504         }
 505 out_revert_creds:
 506         revert_creds(old_cred);
 507         return err;
 508 }
 509
 510 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 511                              const char *link)
 512 {
 513         int err;
 514         struct inode *inode;
 515         struct ovl_cattr attr = {
 516                 .rdev = rdev,
 517                 .link = link,
 518         };
 519
 520         err = ovl_want_write(dentry);
 521         if (err)
 522                 goto out;
 523
 524         err = -ENOMEM;
 525         inode = ovl_new_inode(dentry->d_sb, mode, rdev);
 526         if (!inode)
 527                 goto out_drop_write;
 528
 529         inode_init_owner(inode, dentry->d_parent->d_inode, mode);
 530         attr.mode = inode->i_mode;
 531
 532         err = ovl_create_or_link(dentry, inode, &attr, false);
 533         if (err)
 534                 iput(inode);
 535
 536 out_drop_write:
 537         ovl_drop_write(dentry);
 538 out:
 539         return err;
 540 }
 541
 542 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 543                       bool excl)
 544 {
 545         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 546 }
 547
 548 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 549 {
 550         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 551 }
 552
 553 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 554                      dev_t rdev)
 555 {
 556         /* Don't allow creation of "whiteout" on overlay */
 557         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
 558                 return -EPERM;
 559
 560         return ovl_create_object(dentry, mode, rdev, NULL);
 561 }
 562
 563 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
 564                        const char *link)
 565 {
 566         return ovl_create_object(dentry, S_IFLNK, 0, link);
 567 }
 568
 569 static int ovl_link(struct dentry *old, struct inode *newdir,
 570                     struct dentry *new)
 571 {
 572         int err;
 573         bool locked = false;
 574         struct inode *inode;
 575
 576         err = ovl_want_write(old);
 577         if (err)
 578                 goto out;
 579
 580         err = ovl_copy_up(old);
 581         if (err)
 582                 goto out_drop_write;
 583
 584         err = ovl_nlink_start(old, &locked);
 585         if (err)
 586                 goto out_drop_write;
 587
 588         inode = d_inode(old);
 589         ihold(inode);
 590
 591         err = ovl_create_or_link(new, inode,
 592                         &(struct ovl_cattr) {.hardlink = ovl_dentry_upper(old)},
 593                         ovl_type_origin(old));
 594         if (err)
 595                 iput(inode);
 596
 597         ovl_nlink_end(old, locked);
 598 out_drop_write:
 599         ovl_drop_write(old);
 600 out:
 601         return err;
 602 }
 603
 604 static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper)
 605 {
 606         return d_inode(ovl_dentry_upper(dentry)) == d_inode(upper);
 607 }
 608
 609 static int ovl_remove_and_whiteout(struct dentry *dentry,
 610                                    struct list_head *list)
 611 {
 612         struct dentry *workdir = ovl_workdir(dentry);
 613         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 614         struct dentry *upper;
 615         struct dentry *opaquedir = NULL;
 616         int err;
 617
 618         if (WARN_ON(!workdir))
 619                 return -EROFS;
 620
 621         if (!list_empty(list)) {
 622                 opaquedir = ovl_clear_empty(dentry, list);
 623                 err = PTR_ERR(opaquedir);
 624                 if (IS_ERR(opaquedir))
 625                         goto out;
 626         }
 627
 628         err = ovl_lock_rename_workdir(workdir, upperdir);
 629         if (err)
 630                 goto out_dput;
 631
 632         upper = lookup_one_len(dentry->d_name.name, upperdir,
 633                                dentry->d_name.len);
 634         err = PTR_ERR(upper);
 635         if (IS_ERR(upper))
 636                 goto out_unlock;
 637
 638         err = -ESTALE;
 639         if ((opaquedir && upper != opaquedir) ||
 640             (!opaquedir && ovl_dentry_upper(dentry) &&
 641              !ovl_matches_upper(dentry, upper))) {
 642                 goto out_dput_upper;
 643         }
 644
 645         err = ovl_cleanup_and_whiteout(workdir, d_inode(upperdir), upper);
 646         if (err)
 647                 goto out_d_drop;
 648
 649         ovl_dentry_version_inc(dentry->d_parent, true);
 650 out_d_drop:
 651         d_drop(dentry);
 652 out_dput_upper:
 653         dput(upper);
 654 out_unlock:
 655         unlock_rename(workdir, upperdir);
 656 out_dput:
 657         dput(opaquedir);
 658 out:
 659         return err;
 660 }
 661
 662 static int ovl_remove_upper(struct dentry *dentry, bool is_dir,
 663                             struct list_head *list)
 664 {
 665         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 666         struct inode *dir = upperdir->d_inode;
 667         struct dentry *upper;
 668         struct dentry *opaquedir = NULL;
 669         int err;
 670
 671         if (!list_empty(list)) {
 672                 opaquedir = ovl_clear_empty(dentry, list);
 673                 err = PTR_ERR(opaquedir);
 674                 if (IS_ERR(opaquedir))
 675                         goto out;
 676         }
 677
 678         inode_lock_nested(dir, I_MUTEX_PARENT);
 679         upper = lookup_one_len(dentry->d_name.name, upperdir,
 680                                dentry->d_name.len);
 681         err = PTR_ERR(upper);
 682         if (IS_ERR(upper))
 683                 goto out_unlock;
 684
 685         err = -ESTALE;
 686         if ((opaquedir && upper != opaquedir) ||
 687             (!opaquedir && !ovl_matches_upper(dentry, upper)))
 688                 goto out_dput_upper;
 689
 690         if (is_dir)
 691                 err = vfs_rmdir(dir, upper);
 692         else
 693                 err = vfs_unlink(dir, upper, NULL);
 694         ovl_dentry_version_inc(dentry->d_parent, ovl_type_origin(dentry));
 695
 696         /*
 697          * Keeping this dentry hashed would mean having to release
 698          * upperpath/lowerpath, which could only be done if we are the
 699          * sole user of this dentry.  Too tricky...  Just unhash for
 700          * now.
 701          */
 702         if (!err)
 703                 d_drop(dentry);
 704 out_dput_upper:
 705         dput(upper);
 706 out_unlock:
 707         inode_unlock(dir);
 708         dput(opaquedir);
 709 out:
 710         return err;
 711 }
 712
 713 static bool ovl_pure_upper(struct dentry *dentry)
 714 {
 715         return !ovl_dentry_lower(dentry) &&
 716                !ovl_test_flag(OVL_WHITEOUTS, d_inode(dentry));
 717 }
 718
 719 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 720 {
 721         int err;
 722         bool locked = false;
 723         const struct cred *old_cred;
 724         bool lower_positive = ovl_lower_positive(dentry);
 725         LIST_HEAD(list);
 726
 727         /* No need to clean pure upper removed by vfs_rmdir() */
 728         if (is_dir && (lower_positive || !ovl_pure_upper(dentry))) {
 729                 err = ovl_check_empty_dir(dentry, &list);
 730                 if (err)
 731                         goto out;
 732         }
 733
 734         err = ovl_want_write(dentry);
 735         if (err)
 736                 goto out;
 737
 738         err = ovl_copy_up(dentry->d_parent);
 739         if (err)
 740                 goto out_drop_write;
 741
 742         err = ovl_nlink_start(dentry, &locked);
 743         if (err)
 744                 goto out_drop_write;
 745
 746         old_cred = ovl_override_creds(dentry->d_sb);
 747         if (!lower_positive)
 748                 err = ovl_remove_upper(dentry, is_dir, &list);
 749         else
 750                 err = ovl_remove_and_whiteout(dentry, &list);
 751         revert_creds(old_cred);
 752         if (!err) {
 753                 if (is_dir)
 754                         clear_nlink(dentry->d_inode);
 755                 else
 756                         drop_nlink(dentry->d_inode);
 757         }
 758         ovl_nlink_end(dentry, locked);
 759 out_drop_write:
 760         ovl_drop_write(dentry);
 761 out:
 762         ovl_cache_free(&list);
 763         return err;
 764 }
 765
 766 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
 767 {
 768         return ovl_do_remove(dentry, false);
 769 }
 770
 771 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 772 {
 773         return ovl_do_remove(dentry, true);
 774 }
 775
 776 static bool ovl_type_merge_or_lower(struct dentry *dentry)
 777 {
 778         enum ovl_path_type type = ovl_path_type(dentry);
 779
 780         return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type);
 781 }
 782
 783 static bool ovl_can_move(struct dentry *dentry)
 784 {
 785         return ovl_redirect_dir(dentry->d_sb) ||
 786                 !d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry);
 787 }
 788
 789 static char *ovl_get_redirect(struct dentry *dentry, bool samedir)
 790 {
 791         char *buf, *ret;
 792         struct dentry *d, *tmp;
 793         int buflen = ovl_redirect_max + 1;
 794
 795         if (samedir) {
 796                 ret = kstrndup(dentry->d_name.name, dentry->d_name.len,
 797                                GFP_KERNEL);
 798                 goto out;
 799         }
 800
 801         buf = ret = kmalloc(buflen, GFP_KERNEL);
 802         if (!buf)
 803                 goto out;
 804
 805         buflen--;
 806         buf[buflen] = '\0';
 807         for (d = dget(dentry); !IS_ROOT(d);) {
 808                 const char *name;
 809                 int thislen;
 810
 811                 spin_lock(&d->d_lock);
 812                 name = ovl_dentry_get_redirect(d);
 813                 if (name) {
 814                         thislen = strlen(name);
 815                 } else {
 816                         name = d->d_name.name;
 817                         thislen = d->d_name.len;
 818                 }
 819
 820                 /* If path is too long, fall back to userspace move */
 821                 if (thislen + (name[0] != '/') > buflen) {
 822                         ret = ERR_PTR(-EXDEV);
 823                         spin_unlock(&d->d_lock);
 824                         goto out_put;
 825                 }
 826
 827                 buflen -= thislen;
 828                 memcpy(&buf[buflen], name, thislen);
 829                 tmp = dget_dlock(d->d_parent);
 830                 spin_unlock(&d->d_lock);
 831
 832                 dput(d);
 833                 d = tmp;
 834
 835                 /* Absolute redirect: finished */
 836                 if (buf[buflen] == '/')
 837                         break;
 838                 buflen--;
 839                 buf[buflen] = '/';
 840         }
 841         ret = kstrdup(&buf[buflen], GFP_KERNEL);
 842 out_put:
 843         dput(d);
 844         kfree(buf);
 845 out:
 846         return ret ? ret : ERR_PTR(-ENOMEM);
 847 }
 848
 849 static int ovl_set_redirect(struct dentry *dentry, bool samedir)
 850 {
 851         int err;
 852         const char *redirect = ovl_dentry_get_redirect(dentry);
 853
 854         if (redirect && (samedir || redirect[0] == '/'))
 855                 return 0;
 856
 857         redirect = ovl_get_redirect(dentry, samedir);
 858         if (IS_ERR(redirect))
 859                 return PTR_ERR(redirect);
 860
 861         err = ovl_check_setxattr(dentry, ovl_dentry_upper(dentry),
 862                                  OVL_XATTR_REDIRECT,
 863                                  redirect, strlen(redirect), -EXDEV);
 864         if (!err) {
 865                 spin_lock(&dentry->d_lock);
 866                 ovl_dentry_set_redirect(dentry, redirect);
 867                 spin_unlock(&dentry->d_lock);
 868         } else {
 869                 kfree(redirect);
 870                 pr_warn_ratelimited("overlayfs: failed to set redirect (%i)\n",
 871                                     err);
 872                 /* Fall back to userspace copy-up */
 873                 err = -EXDEV;
 874         }
 875         return err;
 876 }
 877
 878 static int ovl_rename(struct inode *olddir, struct dentry *old,
 879                       struct inode *newdir, struct dentry *new,
 880                       unsigned int flags)
 881 {
 882         int err;
 883         bool locked = false;
 884         struct dentry *old_upperdir;
 885         struct dentry *new_upperdir;
 886         struct dentry *olddentry;
 887         struct dentry *newdentry;
 888         struct dentry *trap;
 889         bool old_opaque;
 890         bool new_opaque;
 891         bool cleanup_whiteout = false;
 892         bool overwrite = !(flags & RENAME_EXCHANGE);
 893         bool is_dir = d_is_dir(old);
 894         bool new_is_dir = d_is_dir(new);
 895         bool samedir = olddir == newdir;
 896         struct dentry *opaquedir = NULL;
 897         const struct cred *old_cred = NULL;
 898         LIST_HEAD(list);
 899
 900         err = -EINVAL;
 901         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
 902                 goto out;
 903
 904         flags &= ~RENAME_NOREPLACE;
 905
 906         /* Don't copy up directory trees */
 907         err = -EXDEV;
 908         if (!ovl_can_move(old))
 909                 goto out;
 910         if (!overwrite && !ovl_can_move(new))
 911                 goto out;
 912
 913         if (overwrite && new_is_dir && !ovl_pure_upper(new)) {
 914                 err = ovl_check_empty_dir(new, &list);
 915                 if (err)
 916                         goto out;
 917         }
 918
 919         if (overwrite) {
 920                 if (ovl_lower_positive(old)) {
 921                         if (!ovl_dentry_is_whiteout(new)) {
 922                                 /* Whiteout source */
 923                                 flags |= RENAME_WHITEOUT;
 924                         } else {
 925                                 /* Switch whiteouts */
 926                                 flags |= RENAME_EXCHANGE;
 927                         }
 928                 } else if (is_dir && ovl_dentry_is_whiteout(new)) {
 929                         flags |= RENAME_EXCHANGE;
 930                         cleanup_whiteout = true;
 931                 }
 932         }
 933
 934         err = ovl_want_write(old);
 935         if (err)
 936                 goto out;
 937
 938         err = ovl_copy_up(old);
 939         if (err)
 940                 goto out_drop_write;
 941
 942         err = ovl_copy_up(new->d_parent);
 943         if (err)
 944                 goto out_drop_write;
 945         if (!overwrite) {
 946                 err = ovl_copy_up(new);
 947                 if (err)
 948                         goto out_drop_write;
 949         } else {
 950                 err = ovl_nlink_start(new, &locked);
 951                 if (err)
 952                         goto out_drop_write;
 953         }
 954
 955         old_cred = ovl_override_creds(old->d_sb);
 956
 957         if (!list_empty(&list)) {
 958                 opaquedir = ovl_clear_empty(new, &list);
 959                 err = PTR_ERR(opaquedir);
 960                 if (IS_ERR(opaquedir)) {
 961                         opaquedir = NULL;
 962                         goto out_revert_creds;
 963                 }
 964         }
 965
 966         old_upperdir = ovl_dentry_upper(old->d_parent);
 967         new_upperdir = ovl_dentry_upper(new->d_parent);
 968
 969         if (!samedir) {
 970                 /*
 971                  * When moving a merge dir or non-dir with copy up origin into
 972                  * a new parent, we are marking the new parent dir "impure".
 973                  * When ovl_iterate() iterates an "impure" upper dir, it will
 974                  * lookup the origin inodes of the entries to fill d_ino.
 975                  */
 976                 if (ovl_type_origin(old)) {
 977                         err = ovl_set_impure(new->d_parent, new_upperdir);
 978                         if (err)
 979                                 goto out_revert_creds;
 980                 }
 981                 if (!overwrite && ovl_type_origin(new)) {
 982                         err = ovl_set_impure(old->d_parent, old_upperdir);
 983                         if (err)
 984                                 goto out_revert_creds;
 985                 }
 986         }
 987
 988         trap = lock_rename(new_upperdir, old_upperdir);
 989
 990         olddentry = lookup_one_len(old->d_name.name, old_upperdir,
 991                                    old->d_name.len);
 992         err = PTR_ERR(olddentry);
 993         if (IS_ERR(olddentry))
 994                 goto out_unlock;
 995
 996         err = -ESTALE;
 997         if (!ovl_matches_upper(old, olddentry))
 998                 goto out_dput_old;
 999
1000         newdentry = lookup_one_len(new->d_name.name, new_upperdir,
1001                                    new->d_name.len);
1002         err = PTR_ERR(newdentry);
1003         if (IS_ERR(newdentry))
1004                 goto out_dput_old;
1005
1006         old_opaque = ovl_dentry_is_opaque(old);
1007         new_opaque = ovl_dentry_is_opaque(new);
1008
1009         err = -ESTALE;
1010         if (d_inode(new) && ovl_dentry_upper(new)) {
1011                 if (opaquedir) {
1012                         if (newdentry != opaquedir)
1013                                 goto out_dput;
1014                 } else {
1015                         if (!ovl_matches_upper(new, newdentry))
1016                                 goto out_dput;
1017                 }
1018         } else {
1019                 if (!d_is_negative(newdentry) &&
1020                     (!new_opaque || !ovl_is_whiteout(newdentry)))
1021                         goto out_dput;
1022         }
1023
1024         if (olddentry == trap)
1025                 goto out_dput;
1026         if (newdentry == trap)
1027                 goto out_dput;
1028
1029         if (WARN_ON(olddentry->d_inode == newdentry->d_inode))
1030                 goto out_dput;
1031
1032         err = 0;
1033         if (is_dir) {
1034                 if (ovl_type_merge_or_lower(old))
1035                         err = ovl_set_redirect(old, samedir);
1036                 else if (!old_opaque && ovl_type_merge(new->d_parent))
1037                         err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
1038                 if (err)
1039                         goto out_dput;
1040         }
1041         if (!overwrite && new_is_dir) {
1042                 if (ovl_type_merge_or_lower(new))
1043                         err = ovl_set_redirect(new, samedir);
1044                 else if (!new_opaque && ovl_type_merge(old->d_parent))
1045                         err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
1046                 if (err)
1047                         goto out_dput;
1048         }
1049
1050         err = ovl_do_rename(old_upperdir->d_inode, olddentry,
1051                             new_upperdir->d_inode, newdentry, flags);
1052         if (err)
1053                 goto out_dput;
1054
1055         if (cleanup_whiteout)
1056                 ovl_cleanup(old_upperdir->d_inode, newdentry);
1057
1058         if (overwrite && d_inode(new)) {
1059                 if (new_is_dir)
1060                         clear_nlink(d_inode(new));
1061                 else
1062                         drop_nlink(d_inode(new));
1063         }
1064
1065         ovl_dentry_version_inc(old->d_parent, ovl_type_origin(old) ||
1066                                (!overwrite && ovl_type_origin(new)));
1067         ovl_dentry_version_inc(new->d_parent, ovl_type_origin(old) ||
1068                                (d_inode(new) && ovl_type_origin(new)));
1069
1070 out_dput:
1071         dput(newdentry);
1072 out_dput_old:
1073         dput(olddentry);
1074 out_unlock:
1075         unlock_rename(new_upperdir, old_upperdir);
1076 out_revert_creds:
1077         revert_creds(old_cred);
1078         ovl_nlink_end(new, locked);
1079 out_drop_write:
1080         ovl_drop_write(old);
1081 out:
1082         dput(opaquedir);
1083         ovl_cache_free(&list);
1084         return err;
1085 }
1086
1087 const struct inode_operations ovl_dir_inode_operations = {
1088         .lookup         = ovl_lookup,
1089         .mkdir          = ovl_mkdir,
1090         .symlink        = ovl_symlink,
1091         .unlink         = ovl_unlink,
1092         .rmdir          = ovl_rmdir,
1093         .rename         = ovl_rename,
1094         .link           = ovl_link,
1095         .setattr        = ovl_setattr,
1096         .create         = ovl_create,
1097         .mknod          = ovl_mknod,
1098         .permission     = ovl_permission,
1099         .getattr        = ovl_getattr,
1100         .listxattr      = ovl_listxattr,
1101         .get_acl        = ovl_get_acl,
1102         .update_time    = ovl_update_time,
1103 };