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                                    struct dentry *dentry)
  68 {
  69         int err;
  70         struct dentry *whiteout;
  71         struct inode *wdir = workdir->d_inode;
  72
  73         whiteout = ovl_lookup_temp(workdir);
  74         if (IS_ERR(whiteout))
  75                 return whiteout;
  76
  77         err = ovl_do_whiteout(wdir, whiteout);
  78         if (err) {
  79                 dput(whiteout);
  80                 whiteout = ERR_PTR(err);
  81         }
  82
  83         return whiteout;
  84 }
  85
  86 int ovl_create_real(struct inode *dir, struct dentry *newdentry,
  87                     struct cattr *attr, struct dentry *hardlink, bool debug)
  88 {
  89         int err;
  90
  91         if (newdentry->d_inode)
  92                 return -ESTALE;
  93
  94         if (hardlink) {
  95                 err = ovl_do_link(hardlink, dir, newdentry, debug);
  96         } else {
  97                 switch (attr->mode & S_IFMT) {
  98                 case S_IFREG:
  99                         err = ovl_do_create(dir, newdentry, attr->mode, debug);
 100                         break;
 101
 102                 case S_IFDIR:
 103                         err = ovl_do_mkdir(dir, newdentry, attr->mode, debug);
 104                         break;
 105
 106                 case S_IFCHR:
 107                 case S_IFBLK:
 108                 case S_IFIFO:
 109                 case S_IFSOCK:
 110                         err = ovl_do_mknod(dir, newdentry,
 111                                            attr->mode, attr->rdev, debug);
 112                         break;
 113
 114                 case S_IFLNK:
 115                         err = ovl_do_symlink(dir, newdentry, attr->link, debug);
 116                         break;
 117
 118                 default:
 119                         err = -EPERM;
 120                 }
 121         }
 122         if (!err && WARN_ON(!newdentry->d_inode)) {
 123                 /*
 124                  * Not quite sure if non-instantiated dentry is legal or not.
 125                  * VFS doesn't seem to care so check and warn here.
 126                  */
 127                 err = -ENOENT;
 128         }
 129         return err;
 130 }
 131
 132 static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper,
 133                                int xerr)
 134 {
 135         int err;
 136
 137         err = ovl_check_setxattr(dentry, upper, OVL_XATTR_OPAQUE, "y", 1, xerr);
 138         if (!err)
 139                 ovl_dentry_set_opaque(dentry);
 140
 141         return err;
 142 }
 143
 144 static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
 145 {
 146         /*
 147          * Fail with -EIO when trying to create opaque dir and upper doesn't
 148          * support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to
 149          * return a specific error for noxattr case.
 150          */
 151         return ovl_set_opaque_xerr(dentry, upperdentry, -EIO);
 152 }
 153
 154 /* Common operations required to be done after creation of file on upper */
 155 static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
 156                             struct dentry *newdentry, bool hardlink)
 157 {
 158         ovl_dentry_version_inc(dentry->d_parent);
 159         ovl_dentry_set_upper_alias(dentry);
 160         if (!hardlink) {
 161                 ovl_inode_update(inode, newdentry);
 162                 ovl_copyattr(newdentry->d_inode, inode);
 163         } else {
 164                 WARN_ON(ovl_inode_real(inode) != d_inode(newdentry));
 165                 dput(newdentry);
 166                 inc_nlink(inode);
 167         }
 168         d_instantiate(dentry, inode);
 169         /* Force lookup of new upper hardlink to find its lower */
 170         if (hardlink)
 171                 d_drop(dentry);
 172 }
 173
 174 static bool ovl_type_merge(struct dentry *dentry)
 175 {
 176         return OVL_TYPE_MERGE(ovl_path_type(dentry));
 177 }
 178
 179 static bool ovl_type_origin(struct dentry *dentry)
 180 {
 181         return OVL_TYPE_ORIGIN(ovl_path_type(dentry));
 182 }
 183
 184 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
 185                             struct cattr *attr, struct dentry *hardlink)
 186 {
 187         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 188         struct inode *udir = upperdir->d_inode;
 189         struct dentry *newdentry;
 190         int err;
 191
 192         if (!hardlink && !IS_POSIXACL(udir))
 193                 attr->mode &= ~current_umask();
 194
 195         inode_lock_nested(udir, I_MUTEX_PARENT);
 196         newdentry = lookup_one_len(dentry->d_name.name, upperdir,
 197                                    dentry->d_name.len);
 198         err = PTR_ERR(newdentry);
 199         if (IS_ERR(newdentry))
 200                 goto out_unlock;
 201         err = ovl_create_real(udir, newdentry, attr, hardlink, false);
 202         if (err)
 203                 goto out_dput;
 204
 205         if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry)) {
 206                 /* Setting opaque here is just an optimization, allow to fail */
 207                 ovl_set_opaque(dentry, newdentry);
 208         }
 209
 210         ovl_instantiate(dentry, inode, newdentry, !!hardlink);
 211         newdentry = NULL;
 212 out_dput:
 213         dput(newdentry);
 214 out_unlock:
 215         inode_unlock(udir);
 216         return err;
 217 }
 218
 219 static int ovl_lock_rename_workdir(struct dentry *workdir,
 220                                    struct dentry *upperdir)
 221 {
 222         /* Workdir should not be the same as upperdir */
 223         if (workdir == upperdir)
 224                 goto err;
 225
 226         /* Workdir should not be subdir of upperdir and vice versa */
 227         if (lock_rename(workdir, upperdir) != NULL)
 228                 goto err_unlock;
 229
 230         return 0;
 231
 232 err_unlock:
 233         unlock_rename(workdir, upperdir);
 234 err:
 235         pr_err("overlayfs: failed to lock workdir+upperdir\n");
 236         return -EIO;
 237 }
 238
 239 static struct dentry *ovl_clear_empty(struct dentry *dentry,
 240                                       struct list_head *list)
 241 {
 242         struct dentry *workdir = ovl_workdir(dentry);
 243         struct inode *wdir = workdir->d_inode;
 244         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 245         struct inode *udir = upperdir->d_inode;
 246         struct path upperpath;
 247         struct dentry *upper;
 248         struct dentry *opaquedir;
 249         struct kstat stat;
 250         int err;
 251
 252         if (WARN_ON(!workdir))
 253                 return ERR_PTR(-EROFS);
 254
 255         err = ovl_lock_rename_workdir(workdir, upperdir);
 256         if (err)
 257                 goto out;
 258
 259         ovl_path_upper(dentry, &upperpath);
 260         err = vfs_getattr(&upperpath, &stat,
 261                           STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
 262         if (err)
 263                 goto out_unlock;
 264
 265         err = -ESTALE;
 266         if (!S_ISDIR(stat.mode))
 267                 goto out_unlock;
 268         upper = upperpath.dentry;
 269         if (upper->d_parent->d_inode != udir)
 270                 goto out_unlock;
 271
 272         opaquedir = ovl_lookup_temp(workdir);
 273         err = PTR_ERR(opaquedir);
 274         if (IS_ERR(opaquedir))
 275                 goto out_unlock;
 276
 277         err = ovl_create_real(wdir, opaquedir,
 278                               &(struct cattr){.mode = stat.mode}, NULL, true);
 279         if (err)
 280                 goto out_dput;
 281
 282         err = ovl_copy_xattr(upper, opaquedir);
 283         if (err)
 284                 goto out_cleanup;
 285
 286         err = ovl_set_opaque(dentry, opaquedir);
 287         if (err)
 288                 goto out_cleanup;
 289
 290         inode_lock(opaquedir->d_inode);
 291         err = ovl_set_attr(opaquedir, &stat);
 292         inode_unlock(opaquedir->d_inode);
 293         if (err)
 294                 goto out_cleanup;
 295
 296         err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
 297         if (err)
 298                 goto out_cleanup;
 299
 300         ovl_cleanup_whiteouts(upper, list);
 301         ovl_cleanup(wdir, upper);
 302         unlock_rename(workdir, upperdir);
 303
 304         /* dentry's upper doesn't match now, get rid of it */
 305         d_drop(dentry);
 306
 307         return opaquedir;
 308
 309 out_cleanup:
 310         ovl_cleanup(wdir, opaquedir);
 311 out_dput:
 312         dput(opaquedir);
 313 out_unlock:
 314         unlock_rename(workdir, upperdir);
 315 out:
 316         return ERR_PTR(err);
 317 }
 318
 319 static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
 320 {
 321         int err;
 322         struct dentry *ret = NULL;
 323         enum ovl_path_type type = ovl_path_type(dentry);
 324         LIST_HEAD(list);
 325
 326         err = ovl_check_empty_dir(dentry, &list);
 327         if (err) {
 328                 ret = ERR_PTR(err);
 329                 goto out_free;
 330         }
 331
 332         /*
 333          * When removing an empty opaque directory, then it makes no sense to
 334          * replace it with an exact replica of itself.
 335          *
 336          * If no upperdentry then skip clearing whiteouts.
 337          *
 338          * Can race with copy-up, since we don't hold the upperdir mutex.
 339          * Doesn't matter, since copy-up can't create a non-empty directory
 340          * from an empty one.
 341          */
 342         if (OVL_TYPE_UPPER(type) && OVL_TYPE_MERGE(type))
 343                 ret = ovl_clear_empty(dentry, &list);
 344
 345 out_free:
 346         ovl_cache_free(&list);
 347
 348         return ret;
 349 }
 350
 351 static int ovl_set_upper_acl(struct dentry *upperdentry, const char *name,
 352                              const struct posix_acl *acl)
 353 {
 354         void *buffer;
 355         size_t size;
 356         int err;
 357
 358         if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl)
 359                 return 0;
 360
 361         size = posix_acl_to_xattr(NULL, acl, NULL, 0);
 362         buffer = kmalloc(size, GFP_KERNEL);
 363         if (!buffer)
 364                 return -ENOMEM;
 365
 366         size = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
 367         err = size;
 368         if (err < 0)
 369                 goto out_free;
 370
 371         err = vfs_setxattr(upperdentry, name, buffer, size, XATTR_CREATE);
 372 out_free:
 373         kfree(buffer);
 374         return err;
 375 }
 376
 377 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 378                                     struct cattr *cattr,
 379                                     struct dentry *hardlink)
 380 {
 381         struct dentry *workdir = ovl_workdir(dentry);
 382         struct inode *wdir = workdir->d_inode;
 383         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 384         struct inode *udir = upperdir->d_inode;
 385         struct dentry *upper;
 386         struct dentry *newdentry;
 387         int err;
 388         struct posix_acl *acl, *default_acl;
 389
 390         if (WARN_ON(!workdir))
 391                 return -EROFS;
 392
 393         if (!hardlink) {
 394                 err = posix_acl_create(dentry->d_parent->d_inode,
 395                                        &cattr->mode, &default_acl, &acl);
 396                 if (err)
 397                         return err;
 398         }
 399
 400         err = ovl_lock_rename_workdir(workdir, upperdir);
 401         if (err)
 402                 goto out;
 403
 404         newdentry = ovl_lookup_temp(workdir);
 405         err = PTR_ERR(newdentry);
 406         if (IS_ERR(newdentry))
 407                 goto out_unlock;
 408
 409         upper = lookup_one_len(dentry->d_name.name, upperdir,
 410                                dentry->d_name.len);
 411         err = PTR_ERR(upper);
 412         if (IS_ERR(upper))
 413                 goto out_dput;
 414
 415         err = ovl_create_real(wdir, newdentry, cattr, hardlink, true);
 416         if (err)
 417                 goto out_dput2;
 418
 419         /*
 420          * mode could have been mutilated due to umask (e.g. sgid directory)
 421          */
 422         if (!hardlink &&
 423             !S_ISLNK(cattr->mode) &&
 424             newdentry->d_inode->i_mode != cattr->mode) {
 425                 struct iattr attr = {
 426                         .ia_valid = ATTR_MODE,
 427                         .ia_mode = cattr->mode,
 428                 };
 429                 inode_lock(newdentry->d_inode);
 430                 err = notify_change(newdentry, &attr, NULL);
 431                 inode_unlock(newdentry->d_inode);
 432                 if (err)
 433                         goto out_cleanup;
 434         }
 435         if (!hardlink) {
 436                 err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_ACCESS,
 437                                         acl);
 438                 if (err)
 439                         goto out_cleanup;
 440
 441                 err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_DEFAULT,
 442                                         default_acl);
 443                 if (err)
 444                         goto out_cleanup;
 445         }
 446
 447         if (!hardlink && S_ISDIR(cattr->mode)) {
 448                 err = ovl_set_opaque(dentry, newdentry);
 449                 if (err)
 450                         goto out_cleanup;
 451
 452                 err = ovl_do_rename(wdir, newdentry, udir, upper,
 453                                     RENAME_EXCHANGE);
 454                 if (err)
 455                         goto out_cleanup;
 456
 457                 ovl_cleanup(wdir, upper);
 458         } else {
 459                 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
 460                 if (err)
 461                         goto out_cleanup;
 462         }
 463         ovl_instantiate(dentry, inode, newdentry, !!hardlink);
 464         newdentry = NULL;
 465 out_dput2:
 466         dput(upper);
 467 out_dput:
 468         dput(newdentry);
 469 out_unlock:
 470         unlock_rename(workdir, upperdir);
 471 out:
 472         if (!hardlink) {
 473                 posix_acl_release(acl);
 474                 posix_acl_release(default_acl);
 475         }
 476         return err;
 477
 478 out_cleanup:
 479         ovl_cleanup(wdir, newdentry);
 480         goto out_dput2;
 481 }
 482
 483 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
 484                               struct cattr *attr, struct dentry *hardlink,
 485                               bool origin)
 486 {
 487         int err;
 488         const struct cred *old_cred;
 489         struct cred *override_cred;
 490         struct dentry *parent = dentry->d_parent;
 491
 492         err = ovl_copy_up(parent);
 493         if (err)
 494                 return err;
 495
 496         old_cred = ovl_override_creds(dentry->d_sb);
 497
 498         /*
 499          * When linking a file with copy up origin into a new parent, mark the
 500          * new parent dir "impure".
 501          */
 502         if (origin) {
 503                 err = ovl_set_impure(parent, ovl_dentry_upper(parent));
 504                 if (err)
 505                         goto out_revert_creds;
 506         }
 507
 508         err = -ENOMEM;
 509         override_cred = prepare_creds();
 510         if (override_cred) {
 511                 override_cred->fsuid = inode->i_uid;
 512                 override_cred->fsgid = inode->i_gid;
 513                 if (!hardlink) {
 514                         err = security_dentry_create_files_as(dentry,
 515                                         attr->mode, &dentry->d_name, old_cred,
 516                                         override_cred);
 517                         if (err) {
 518                                 put_cred(override_cred);
 519                                 goto out_revert_creds;
 520                         }
 521                 }
 522                 put_cred(override_creds(override_cred));
 523                 put_cred(override_cred);
 524
 525                 if (!ovl_dentry_is_whiteout(dentry))
 526                         err = ovl_create_upper(dentry, inode, attr,
 527                                                 hardlink);
 528                 else
 529                         err = ovl_create_over_whiteout(dentry, inode, attr,
 530                                                         hardlink);
 531         }
 532 out_revert_creds:
 533         revert_creds(old_cred);
 534         if (!err) {
 535                 struct inode *realinode = d_inode(ovl_dentry_upper(dentry));
 536
 537                 WARN_ON(inode->i_mode != realinode->i_mode);
 538                 WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
 539                 WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
 540         }
 541         return err;
 542 }
 543
 544 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 545                              const char *link)
 546 {
 547         int err;
 548         struct inode *inode;
 549         struct cattr attr = {
 550                 .rdev = rdev,
 551                 .link = link,
 552         };
 553
 554         err = ovl_want_write(dentry);
 555         if (err)
 556                 goto out;
 557
 558         err = -ENOMEM;
 559         inode = ovl_new_inode(dentry->d_sb, mode, rdev);
 560         if (!inode)
 561                 goto out_drop_write;
 562
 563         inode_init_owner(inode, dentry->d_parent->d_inode, mode);
 564         attr.mode = inode->i_mode;
 565
 566         err = ovl_create_or_link(dentry, inode, &attr, NULL, false);
 567         if (err)
 568                 iput(inode);
 569
 570 out_drop_write:
 571         ovl_drop_write(dentry);
 572 out:
 573         return err;
 574 }
 575
 576 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 577                       bool excl)
 578 {
 579         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 580 }
 581
 582 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 583 {
 584         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 585 }
 586
 587 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 588                      dev_t rdev)
 589 {
 590         /* Don't allow creation of "whiteout" on overlay */
 591         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
 592                 return -EPERM;
 593
 594         return ovl_create_object(dentry, mode, rdev, NULL);
 595 }
 596
 597 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
 598                        const char *link)
 599 {
 600         return ovl_create_object(dentry, S_IFLNK, 0, link);
 601 }
 602
 603 static int ovl_link(struct dentry *old, struct inode *newdir,
 604                     struct dentry *new)
 605 {
 606         int err;
 607         bool locked = false;
 608         struct inode *inode;
 609
 610         err = ovl_want_write(old);
 611         if (err)
 612                 goto out;
 613
 614         err = ovl_copy_up(old);
 615         if (err)
 616                 goto out_drop_write;
 617
 618         err = ovl_nlink_start(old, &locked);
 619         if (err)
 620                 goto out_drop_write;
 621
 622         inode = d_inode(old);
 623         ihold(inode);
 624
 625         err = ovl_create_or_link(new, inode, NULL, ovl_dentry_upper(old),
 626                                  ovl_type_origin(old));
 627         if (err)
 628                 iput(inode);
 629
 630         ovl_nlink_end(old, locked);
 631 out_drop_write:
 632         ovl_drop_write(old);
 633 out:
 634         return err;
 635 }
 636
 637 static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper)
 638 {
 639         return d_inode(ovl_dentry_upper(dentry)) == d_inode(upper);
 640 }
 641
 642 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
 643 {
 644         struct dentry *workdir = ovl_workdir(dentry);
 645         struct inode *wdir = workdir->d_inode;
 646         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 647         struct inode *udir = upperdir->d_inode;
 648         struct dentry *whiteout;
 649         struct dentry *upper;
 650         struct dentry *opaquedir = NULL;
 651         int err;
 652         int flags = 0;
 653
 654         if (WARN_ON(!workdir))
 655                 return -EROFS;
 656
 657         if (is_dir) {
 658                 opaquedir = ovl_check_empty_and_clear(dentry);
 659                 err = PTR_ERR(opaquedir);
 660                 if (IS_ERR(opaquedir))
 661                         goto out;
 662         }
 663
 664         err = ovl_lock_rename_workdir(workdir, upperdir);
 665         if (err)
 666                 goto out_dput;
 667
 668         upper = lookup_one_len(dentry->d_name.name, upperdir,
 669                                dentry->d_name.len);
 670         err = PTR_ERR(upper);
 671         if (IS_ERR(upper))
 672                 goto out_unlock;
 673
 674         err = -ESTALE;
 675         if ((opaquedir && upper != opaquedir) ||
 676             (!opaquedir && ovl_dentry_upper(dentry) &&
 677              !ovl_matches_upper(dentry, upper))) {
 678                 goto out_dput_upper;
 679         }
 680
 681         whiteout = ovl_whiteout(workdir, dentry);
 682         err = PTR_ERR(whiteout);
 683         if (IS_ERR(whiteout))
 684                 goto out_dput_upper;
 685
 686         if (d_is_dir(upper))
 687                 flags = RENAME_EXCHANGE;
 688
 689         err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
 690         if (err)
 691                 goto kill_whiteout;
 692         if (flags)
 693                 ovl_cleanup(wdir, upper);
 694
 695         ovl_dentry_version_inc(dentry->d_parent);
 696 out_d_drop:
 697         d_drop(dentry);
 698         dput(whiteout);
 699 out_dput_upper:
 700         dput(upper);
 701 out_unlock:
 702         unlock_rename(workdir, upperdir);
 703 out_dput:
 704         dput(opaquedir);
 705 out:
 706         return err;
 707
 708 kill_whiteout:
 709         ovl_cleanup(wdir, whiteout);
 710         goto out_d_drop;
 711 }
 712
 713 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
 714 {
 715         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
 716         struct inode *dir = upperdir->d_inode;
 717         struct dentry *upper;
 718         struct dentry *opaquedir = NULL;
 719         int err;
 720
 721         /* Redirect dir can be !ovl_lower_positive && OVL_TYPE_MERGE */
 722         if (is_dir && ovl_dentry_get_redirect(dentry)) {
 723                 opaquedir = ovl_check_empty_and_clear(dentry);
 724                 err = PTR_ERR(opaquedir);
 725                 if (IS_ERR(opaquedir))
 726                         goto out;
 727         }
 728
 729         inode_lock_nested(dir, I_MUTEX_PARENT);
 730         upper = lookup_one_len(dentry->d_name.name, upperdir,
 731                                dentry->d_name.len);
 732         err = PTR_ERR(upper);
 733         if (IS_ERR(upper))
 734                 goto out_unlock;
 735
 736         err = -ESTALE;
 737         if ((opaquedir && upper != opaquedir) ||
 738             (!opaquedir && !ovl_matches_upper(dentry, upper)))
 739                 goto out_dput_upper;
 740
 741         if (is_dir)
 742                 err = vfs_rmdir(dir, upper);
 743         else
 744                 err = vfs_unlink(dir, upper, NULL);
 745         ovl_dentry_version_inc(dentry->d_parent);
 746
 747         /*
 748          * Keeping this dentry hashed would mean having to release
 749          * upperpath/lowerpath, which could only be done if we are the
 750          * sole user of this dentry.  Too tricky...  Just unhash for
 751          * now.
 752          */
 753         if (!err)
 754                 d_drop(dentry);
 755 out_dput_upper:
 756         dput(upper);
 757 out_unlock:
 758         inode_unlock(dir);
 759         dput(opaquedir);
 760 out:
 761         return err;
 762 }
 763
 764 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 765 {
 766         int err;
 767         bool locked = false;
 768         const struct cred *old_cred;
 769
 770         err = ovl_want_write(dentry);
 771         if (err)
 772                 goto out;
 773
 774         err = ovl_copy_up(dentry->d_parent);
 775         if (err)
 776                 goto out_drop_write;
 777
 778         err = ovl_nlink_start(dentry, &locked);
 779         if (err)
 780                 goto out_drop_write;
 781
 782         old_cred = ovl_override_creds(dentry->d_sb);
 783         if (!ovl_lower_positive(dentry))
 784                 err = ovl_remove_upper(dentry, is_dir);
 785         else
 786                 err = ovl_remove_and_whiteout(dentry, is_dir);
 787         revert_creds(old_cred);
 788         if (!err) {
 789                 if (is_dir)
 790                         clear_nlink(dentry->d_inode);
 791                 else
 792                         drop_nlink(dentry->d_inode);
 793         }
 794         ovl_nlink_end(dentry, locked);
 795 out_drop_write:
 796         ovl_drop_write(dentry);
 797 out:
 798         return err;
 799 }
 800
 801 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
 802 {
 803         return ovl_do_remove(dentry, false);
 804 }
 805
 806 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
 807 {
 808         return ovl_do_remove(dentry, true);
 809 }
 810
 811 static bool ovl_type_merge_or_lower(struct dentry *dentry)
 812 {
 813         enum ovl_path_type type = ovl_path_type(dentry);
 814
 815         return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type);
 816 }
 817
 818 static bool ovl_can_move(struct dentry *dentry)
 819 {
 820         return ovl_redirect_dir(dentry->d_sb) ||
 821                 !d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry);
 822 }
 823
 824 static char *ovl_get_redirect(struct dentry *dentry, bool samedir)
 825 {
 826         char *buf, *ret;
 827         struct dentry *d, *tmp;
 828         int buflen = ovl_redirect_max + 1;
 829
 830         if (samedir) {
 831                 ret = kstrndup(dentry->d_name.name, dentry->d_name.len,
 832                                GFP_KERNEL);
 833                 goto out;
 834         }
 835
 836         buf = ret = kmalloc(buflen, GFP_TEMPORARY);
 837         if (!buf)
 838                 goto out;
 839
 840         buflen--;
 841         buf[buflen] = '\0';
 842         for (d = dget(dentry); !IS_ROOT(d);) {
 843                 const char *name;
 844                 int thislen;
 845
 846                 spin_lock(&d->d_lock);
 847                 name = ovl_dentry_get_redirect(d);
 848                 if (name) {
 849                         thislen = strlen(name);
 850                 } else {
 851                         name = d->d_name.name;
 852                         thislen = d->d_name.len;
 853                 }
 854
 855                 /* If path is too long, fall back to userspace move */
 856                 if (thislen + (name[0] != '/') > buflen) {
 857                         ret = ERR_PTR(-EXDEV);
 858                         spin_unlock(&d->d_lock);
 859                         goto out_put;
 860                 }
 861
 862                 buflen -= thislen;
 863                 memcpy(&buf[buflen], name, thislen);
 864                 tmp = dget_dlock(d->d_parent);
 865                 spin_unlock(&d->d_lock);
 866
 867                 dput(d);
 868                 d = tmp;
 869
 870                 /* Absolute redirect: finished */
 871                 if (buf[buflen] == '/')
 872                         break;
 873                 buflen--;
 874                 buf[buflen] = '/';
 875         }
 876         ret = kstrdup(&buf[buflen], GFP_KERNEL);
 877 out_put:
 878         dput(d);
 879         kfree(buf);
 880 out:
 881         return ret ? ret : ERR_PTR(-ENOMEM);
 882 }
 883
 884 static int ovl_set_redirect(struct dentry *dentry, bool samedir)
 885 {
 886         int err;
 887         const char *redirect = ovl_dentry_get_redirect(dentry);
 888
 889         if (redirect && (samedir || redirect[0] == '/'))
 890                 return 0;
 891
 892         redirect = ovl_get_redirect(dentry, samedir);
 893         if (IS_ERR(redirect))
 894                 return PTR_ERR(redirect);
 895
 896         err = ovl_check_setxattr(dentry, ovl_dentry_upper(dentry),
 897                                  OVL_XATTR_REDIRECT,
 898                                  redirect, strlen(redirect), -EXDEV);
 899         if (!err) {
 900                 spin_lock(&dentry->d_lock);
 901                 ovl_dentry_set_redirect(dentry, redirect);
 902                 spin_unlock(&dentry->d_lock);
 903         } else {
 904                 kfree(redirect);
 905                 pr_warn_ratelimited("overlay: failed to set redirect (%i)\n", err);
 906                 /* Fall back to userspace copy-up */
 907                 err = -EXDEV;
 908         }
 909         return err;
 910 }
 911
 912 static int ovl_rename(struct inode *olddir, struct dentry *old,
 913                       struct inode *newdir, struct dentry *new,
 914                       unsigned int flags)
 915 {
 916         int err;
 917         bool locked = false;
 918         struct dentry *old_upperdir;
 919         struct dentry *new_upperdir;
 920         struct dentry *olddentry;
 921         struct dentry *newdentry;
 922         struct dentry *trap;
 923         bool old_opaque;
 924         bool new_opaque;
 925         bool cleanup_whiteout = false;
 926         bool overwrite = !(flags & RENAME_EXCHANGE);
 927         bool is_dir = d_is_dir(old);
 928         bool new_is_dir = d_is_dir(new);
 929         bool samedir = olddir == newdir;
 930         struct dentry *opaquedir = NULL;
 931         const struct cred *old_cred = NULL;
 932
 933         err = -EINVAL;
 934         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
 935                 goto out;
 936
 937         flags &= ~RENAME_NOREPLACE;
 938
 939         /* Don't copy up directory trees */
 940         err = -EXDEV;
 941         if (!ovl_can_move(old))
 942                 goto out;
 943         if (!overwrite && !ovl_can_move(new))
 944                 goto out;
 945
 946         err = ovl_want_write(old);
 947         if (err)
 948                 goto out;
 949
 950         err = ovl_copy_up(old);
 951         if (err)
 952                 goto out_drop_write;
 953
 954         err = ovl_copy_up(new->d_parent);
 955         if (err)
 956                 goto out_drop_write;
 957         if (!overwrite) {
 958                 err = ovl_copy_up(new);
 959                 if (err)
 960                         goto out_drop_write;
 961         } else {
 962                 err = ovl_nlink_start(new, &locked);
 963                 if (err)
 964                         goto out_drop_write;
 965         }
 966
 967         old_cred = ovl_override_creds(old->d_sb);
 968
 969         if (overwrite && new_is_dir && ovl_type_merge_or_lower(new)) {
 970                 opaquedir = ovl_check_empty_and_clear(new);
 971                 err = PTR_ERR(opaquedir);
 972                 if (IS_ERR(opaquedir)) {
 973                         opaquedir = NULL;
 974                         goto out_revert_creds;
 975                 }
 976         }
 977
 978         if (overwrite) {
 979                 if (ovl_lower_positive(old)) {
 980                         if (!ovl_dentry_is_whiteout(new)) {
 981                                 /* Whiteout source */
 982                                 flags |= RENAME_WHITEOUT;
 983                         } else {
 984                                 /* Switch whiteouts */
 985                                 flags |= RENAME_EXCHANGE;
 986                         }
 987                 } else if (is_dir && ovl_dentry_is_whiteout(new)) {
 988                         flags |= RENAME_EXCHANGE;
 989                         cleanup_whiteout = true;
 990                 }
 991         }
 992
 993         old_upperdir = ovl_dentry_upper(old->d_parent);
 994         new_upperdir = ovl_dentry_upper(new->d_parent);
 995
 996         if (!samedir) {
 997                 /*
 998                  * When moving a merge dir or non-dir with copy up origin into
 999                  * a new parent, we are marking the new parent dir "impure".
1000                  * When ovl_iterate() iterates an "impure" upper dir, it will
1001                  * lookup the origin inodes of the entries to fill d_ino.
1002                  */
1003                 if (ovl_type_origin(old)) {
1004                         err = ovl_set_impure(new->d_parent, new_upperdir);
1005                         if (err)
1006                                 goto out_revert_creds;
1007                 }
1008                 if (!overwrite && ovl_type_origin(new)) {
1009                         err = ovl_set_impure(old->d_parent, old_upperdir);
1010                         if (err)
1011                                 goto out_revert_creds;
1012                 }
1013         }
1014
1015         trap = lock_rename(new_upperdir, old_upperdir);
1016
1017         olddentry = lookup_one_len(old->d_name.name, old_upperdir,
1018                                    old->d_name.len);
1019         err = PTR_ERR(olddentry);
1020         if (IS_ERR(olddentry))
1021                 goto out_unlock;
1022
1023         err = -ESTALE;
1024         if (!ovl_matches_upper(old, olddentry))
1025                 goto out_dput_old;
1026
1027         newdentry = lookup_one_len(new->d_name.name, new_upperdir,
1028                                    new->d_name.len);
1029         err = PTR_ERR(newdentry);
1030         if (IS_ERR(newdentry))
1031                 goto out_dput_old;
1032
1033         old_opaque = ovl_dentry_is_opaque(old);
1034         new_opaque = ovl_dentry_is_opaque(new);
1035
1036         err = -ESTALE;
1037         if (d_inode(new) && ovl_dentry_upper(new)) {
1038                 if (opaquedir) {
1039                         if (newdentry != opaquedir)
1040                                 goto out_dput;
1041                 } else {
1042                         if (!ovl_matches_upper(new, newdentry))
1043                                 goto out_dput;
1044                 }
1045         } else {
1046                 if (!d_is_negative(newdentry) &&
1047                     (!new_opaque || !ovl_is_whiteout(newdentry)))
1048                         goto out_dput;
1049         }
1050
1051         if (olddentry == trap)
1052                 goto out_dput;
1053         if (newdentry == trap)
1054                 goto out_dput;
1055
1056         if (WARN_ON(olddentry->d_inode == newdentry->d_inode))
1057                 goto out_dput;
1058
1059         err = 0;
1060         if (is_dir) {
1061                 if (ovl_type_merge_or_lower(old))
1062                         err = ovl_set_redirect(old, samedir);
1063                 else if (!old_opaque && ovl_type_merge(new->d_parent))
1064                         err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
1065                 if (err)
1066                         goto out_dput;
1067         }
1068         if (!overwrite && new_is_dir) {
1069                 if (ovl_type_merge_or_lower(new))
1070                         err = ovl_set_redirect(new, samedir);
1071                 else if (!new_opaque && ovl_type_merge(old->d_parent))
1072                         err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
1073                 if (err)
1074                         goto out_dput;
1075         }
1076
1077         err = ovl_do_rename(old_upperdir->d_inode, olddentry,
1078                             new_upperdir->d_inode, newdentry, flags);
1079         if (err)
1080                 goto out_dput;
1081
1082         if (cleanup_whiteout)
1083                 ovl_cleanup(old_upperdir->d_inode, newdentry);
1084
1085         if (overwrite && d_inode(new)) {
1086                 if (new_is_dir)
1087                         clear_nlink(d_inode(new));
1088                 else
1089                         drop_nlink(d_inode(new));
1090         }
1091
1092         ovl_dentry_version_inc(old->d_parent);
1093         ovl_dentry_version_inc(new->d_parent);
1094
1095 out_dput:
1096         dput(newdentry);
1097 out_dput_old:
1098         dput(olddentry);
1099 out_unlock:
1100         unlock_rename(new_upperdir, old_upperdir);
1101 out_revert_creds:
1102         revert_creds(old_cred);
1103         ovl_nlink_end(new, locked);
1104 out_drop_write:
1105         ovl_drop_write(old);
1106 out:
1107         dput(opaquedir);
1108         return err;
1109 }
1110
1111 const struct inode_operations ovl_dir_inode_operations = {
1112         .lookup         = ovl_lookup,
1113         .mkdir          = ovl_mkdir,
1114         .symlink        = ovl_symlink,
1115         .unlink         = ovl_unlink,
1116         .rmdir          = ovl_rmdir,
1117         .rename         = ovl_rename,
1118         .link           = ovl_link,
1119         .setattr        = ovl_setattr,
1120         .create         = ovl_create,
1121         .mknod          = ovl_mknod,
1122         .permission     = ovl_permission,
1123         .getattr        = ovl_getattr,
1124         .listxattr      = ovl_listxattr,
1125         .get_acl        = ovl_get_acl,
1126         .update_time    = ovl_update_time,
1127 };