1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * 4 * Copyright (C) 2011 Novell Inc. 5 */ 6 7 #include <linux/fs.h> 8 #include <linux/namei.h> 9 #include <linux/xattr.h> 10 #include <linux/security.h> 11 #include <linux/cred.h> 12 #include <linux/module.h> 13 #include <linux/posix_acl.h> 14 #include <linux/posix_acl_xattr.h> 15 #include <linux/atomic.h> 16 #include <linux/ratelimit.h> 17 #include "overlayfs.h" 18 19 static unsigned short ovl_redirect_max = 256; 20 module_param_named(redirect_max, ovl_redirect_max, ushort, 0644); 21 MODULE_PARM_DESC(redirect_max, 22 "Maximum length of absolute redirect xattr value"); 23 24 static int ovl_set_redirect(struct dentry *dentry, bool samedir); 25 26 int ovl_cleanup(struct ovl_fs *ofs, struct inode *wdir, struct dentry *wdentry) 27 { 28 int err; 29 30 dget(wdentry); 31 if (d_is_dir(wdentry)) 32 err = ovl_do_rmdir(ofs, wdir, wdentry); 33 else 34 err = ovl_do_unlink(ofs, wdir, wdentry); 35 dput(wdentry); 36 37 if (err) { 38 pr_err("cleanup of '%pd2' failed (%i)\n", 39 wdentry, err); 40 } 41 42 return err; 43 } 44 45 struct dentry *ovl_lookup_temp(struct ovl_fs *ofs, struct dentry *workdir) 46 { 47 struct dentry *temp; 48 char name[20]; 49 static atomic_t temp_id = ATOMIC_INIT(0); 50 51 /* counter is allowed to wrap, since temp dentries are ephemeral */ 52 snprintf(name, sizeof(name), "#%x", atomic_inc_return(&temp_id)); 53 54 temp = ovl_lookup_upper(ofs, name, workdir, strlen(name)); 55 if (!IS_ERR(temp) && temp->d_inode) { 56 pr_err("workdir/%s already exists\n", name); 57 dput(temp); 58 temp = ERR_PTR(-EIO); 59 } 60 61 return temp; 62 } 63 64 /* caller holds i_mutex on workdir */ 65 static struct dentry *ovl_whiteout(struct ovl_fs *ofs) 66 { 67 int err; 68 struct dentry *whiteout; 69 struct dentry *workdir = ofs->workdir; 70 struct inode *wdir = workdir->d_inode; 71 72 if (!ofs->whiteout) { 73 whiteout = ovl_lookup_temp(ofs, workdir); 74 if (IS_ERR(whiteout)) 75 goto out; 76 77 err = ovl_do_whiteout(ofs, wdir, whiteout); 78 if (err) { 79 dput(whiteout); 80 whiteout = ERR_PTR(err); 81 goto out; 82 } 83 ofs->whiteout = whiteout; 84 } 85 86 if (ofs->share_whiteout) { 87 whiteout = ovl_lookup_temp(ofs, workdir); 88 if (IS_ERR(whiteout)) 89 goto out; 90 91 err = ovl_do_link(ofs, ofs->whiteout, wdir, whiteout); 92 if (!err) 93 goto out; 94 95 if (err != -EMLINK) { 96 pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%i)\n", 97 ofs->whiteout->d_inode->i_nlink, err); 98 ofs->share_whiteout = false; 99 } 100 dput(whiteout); 101 } 102 whiteout = ofs->whiteout; 103 ofs->whiteout = NULL; 104 out: 105 return whiteout; 106 } 107 108 /* Caller must hold i_mutex on both workdir and dir */ 109 int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct inode *dir, 110 struct dentry *dentry) 111 { 112 struct inode *wdir = ofs->workdir->d_inode; 113 struct dentry *whiteout; 114 int err; 115 int flags = 0; 116 117 whiteout = ovl_whiteout(ofs); 118 err = PTR_ERR(whiteout); 119 if (IS_ERR(whiteout)) 120 return err; 121 122 if (d_is_dir(dentry)) 123 flags = RENAME_EXCHANGE; 124 125 err = ovl_do_rename(ofs, wdir, whiteout, dir, dentry, flags); 126 if (err) 127 goto kill_whiteout; 128 if (flags) 129 ovl_cleanup(ofs, wdir, dentry); 130 131 out: 132 dput(whiteout); 133 return err; 134 135 kill_whiteout: 136 ovl_cleanup(ofs, wdir, whiteout); 137 goto out; 138 } 139 140 int ovl_mkdir_real(struct ovl_fs *ofs, struct inode *dir, 141 struct dentry **newdentry, umode_t mode) 142 { 143 int err; 144 struct dentry *d, *dentry = *newdentry; 145 146 err = ovl_do_mkdir(ofs, dir, dentry, mode); 147 if (err) 148 return err; 149 150 if (likely(!d_unhashed(dentry))) 151 return 0; 152 153 /* 154 * vfs_mkdir() may succeed and leave the dentry passed 155 * to it unhashed and negative. If that happens, try to 156 * lookup a new hashed and positive dentry. 157 */ 158 d = ovl_lookup_upper(ofs, dentry->d_name.name, dentry->d_parent, 159 dentry->d_name.len); 160 if (IS_ERR(d)) { 161 pr_warn("failed lookup after mkdir (%pd2, err=%i).\n", 162 dentry, err); 163 return PTR_ERR(d); 164 } 165 dput(dentry); 166 *newdentry = d; 167 168 return 0; 169 } 170 171 struct dentry *ovl_create_real(struct ovl_fs *ofs, struct inode *dir, 172 struct dentry *newdentry, struct ovl_cattr *attr) 173 { 174 int err; 175 176 if (IS_ERR(newdentry)) 177 return newdentry; 178 179 err = -ESTALE; 180 if (newdentry->d_inode) 181 goto out; 182 183 if (attr->hardlink) { 184 err = ovl_do_link(ofs, attr->hardlink, dir, newdentry); 185 } else { 186 switch (attr->mode & S_IFMT) { 187 case S_IFREG: 188 err = ovl_do_create(ofs, dir, newdentry, attr->mode); 189 break; 190 191 case S_IFDIR: 192 /* mkdir is special... */ 193 err = ovl_mkdir_real(ofs, dir, &newdentry, attr->mode); 194 break; 195 196 case S_IFCHR: 197 case S_IFBLK: 198 case S_IFIFO: 199 case S_IFSOCK: 200 err = ovl_do_mknod(ofs, dir, newdentry, attr->mode, 201 attr->rdev); 202 break; 203 204 case S_IFLNK: 205 err = ovl_do_symlink(ofs, dir, newdentry, attr->link); 206 break; 207 208 default: 209 err = -EPERM; 210 } 211 } 212 if (!err && WARN_ON(!newdentry->d_inode)) { 213 /* 214 * Not quite sure if non-instantiated dentry is legal or not. 215 * VFS doesn't seem to care so check and warn here. 216 */ 217 err = -EIO; 218 } 219 out: 220 if (err) { 221 dput(newdentry); 222 return ERR_PTR(err); 223 } 224 return newdentry; 225 } 226 227 struct dentry *ovl_create_temp(struct ovl_fs *ofs, struct dentry *workdir, 228 struct ovl_cattr *attr) 229 { 230 return ovl_create_real(ofs, d_inode(workdir), 231 ovl_lookup_temp(ofs, workdir), attr); 232 } 233 234 static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper, 235 int xerr) 236 { 237 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 238 int err; 239 240 err = ovl_check_setxattr(ofs, upper, OVL_XATTR_OPAQUE, "y", 1, xerr); 241 if (!err) 242 ovl_dentry_set_opaque(dentry); 243 244 return err; 245 } 246 247 static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry) 248 { 249 /* 250 * Fail with -EIO when trying to create opaque dir and upper doesn't 251 * support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to 252 * return a specific error for noxattr case. 253 */ 254 return ovl_set_opaque_xerr(dentry, upperdentry, -EIO); 255 } 256 257 /* 258 * Common operations required to be done after creation of file on upper. 259 * If @hardlink is false, then @inode is a pre-allocated inode, we may or 260 * may not use to instantiate the new dentry. 261 */ 262 static int ovl_instantiate(struct dentry *dentry, struct inode *inode, 263 struct dentry *newdentry, bool hardlink) 264 { 265 struct ovl_inode_params oip = { 266 .upperdentry = newdentry, 267 .newinode = inode, 268 }; 269 270 ovl_dir_modified(dentry->d_parent, false); 271 ovl_dentry_set_upper_alias(dentry); 272 ovl_dentry_update_reval(dentry, newdentry, 273 DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); 274 275 if (!hardlink) { 276 /* 277 * ovl_obtain_alias() can be called after ovl_create_real() 278 * and before we get here, so we may get an inode from cache 279 * with the same real upperdentry that is not the inode we 280 * pre-allocated. In this case we will use the cached inode 281 * to instantiate the new dentry. 282 * 283 * XXX: if we ever use ovl_obtain_alias() to decode directory 284 * file handles, need to use ovl_get_inode_locked() and 285 * d_instantiate_new() here to prevent from creating two 286 * hashed directory inode aliases. 287 */ 288 inode = ovl_get_inode(dentry->d_sb, &oip); 289 if (IS_ERR(inode)) 290 return PTR_ERR(inode); 291 if (inode == oip.newinode) 292 ovl_set_flag(OVL_UPPERDATA, inode); 293 } else { 294 WARN_ON(ovl_inode_real(inode) != d_inode(newdentry)); 295 dput(newdentry); 296 inc_nlink(inode); 297 } 298 299 d_instantiate(dentry, inode); 300 if (inode != oip.newinode) { 301 pr_warn_ratelimited("newly created inode found in cache (%pd2)\n", 302 dentry); 303 } 304 305 /* Force lookup of new upper hardlink to find its lower */ 306 if (hardlink) 307 d_drop(dentry); 308 309 return 0; 310 } 311 312 static bool ovl_type_merge(struct dentry *dentry) 313 { 314 return OVL_TYPE_MERGE(ovl_path_type(dentry)); 315 } 316 317 static bool ovl_type_origin(struct dentry *dentry) 318 { 319 return OVL_TYPE_ORIGIN(ovl_path_type(dentry)); 320 } 321 322 static int ovl_create_upper(struct dentry *dentry, struct inode *inode, 323 struct ovl_cattr *attr) 324 { 325 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 326 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 327 struct inode *udir = upperdir->d_inode; 328 struct dentry *newdentry; 329 int err; 330 331 if (!attr->hardlink && !IS_POSIXACL(udir)) 332 attr->mode &= ~current_umask(); 333 334 inode_lock_nested(udir, I_MUTEX_PARENT); 335 newdentry = ovl_create_real(ofs, udir, 336 ovl_lookup_upper(ofs, dentry->d_name.name, 337 upperdir, dentry->d_name.len), 338 attr); 339 err = PTR_ERR(newdentry); 340 if (IS_ERR(newdentry)) 341 goto out_unlock; 342 343 if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry) && 344 !ovl_allow_offline_changes(ofs)) { 345 /* Setting opaque here is just an optimization, allow to fail */ 346 ovl_set_opaque(dentry, newdentry); 347 } 348 349 err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink); 350 if (err) 351 goto out_cleanup; 352 out_unlock: 353 inode_unlock(udir); 354 return err; 355 356 out_cleanup: 357 ovl_cleanup(ofs, udir, newdentry); 358 dput(newdentry); 359 goto out_unlock; 360 } 361 362 static struct dentry *ovl_clear_empty(struct dentry *dentry, 363 struct list_head *list) 364 { 365 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 366 struct dentry *workdir = ovl_workdir(dentry); 367 struct inode *wdir = workdir->d_inode; 368 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 369 struct inode *udir = upperdir->d_inode; 370 struct path upperpath; 371 struct dentry *upper; 372 struct dentry *opaquedir; 373 struct kstat stat; 374 int err; 375 376 if (WARN_ON(!workdir)) 377 return ERR_PTR(-EROFS); 378 379 err = ovl_lock_rename_workdir(workdir, upperdir); 380 if (err) 381 goto out; 382 383 ovl_path_upper(dentry, &upperpath); 384 err = vfs_getattr(&upperpath, &stat, 385 STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT); 386 if (err) 387 goto out_unlock; 388 389 err = -ESTALE; 390 if (!S_ISDIR(stat.mode)) 391 goto out_unlock; 392 upper = upperpath.dentry; 393 if (upper->d_parent->d_inode != udir) 394 goto out_unlock; 395 396 opaquedir = ovl_create_temp(ofs, workdir, OVL_CATTR(stat.mode)); 397 err = PTR_ERR(opaquedir); 398 if (IS_ERR(opaquedir)) 399 goto out_unlock; 400 401 err = ovl_copy_xattr(dentry->d_sb, &upperpath, opaquedir); 402 if (err) 403 goto out_cleanup; 404 405 err = ovl_set_opaque(dentry, opaquedir); 406 if (err) 407 goto out_cleanup; 408 409 inode_lock(opaquedir->d_inode); 410 err = ovl_set_attr(ofs, opaquedir, &stat); 411 inode_unlock(opaquedir->d_inode); 412 if (err) 413 goto out_cleanup; 414 415 err = ovl_do_rename(ofs, wdir, opaquedir, udir, upper, RENAME_EXCHANGE); 416 if (err) 417 goto out_cleanup; 418 419 ovl_cleanup_whiteouts(ofs, upper, list); 420 ovl_cleanup(ofs, wdir, upper); 421 unlock_rename(workdir, upperdir); 422 423 /* dentry's upper doesn't match now, get rid of it */ 424 d_drop(dentry); 425 426 return opaquedir; 427 428 out_cleanup: 429 ovl_cleanup(ofs, wdir, opaquedir); 430 dput(opaquedir); 431 out_unlock: 432 unlock_rename(workdir, upperdir); 433 out: 434 return ERR_PTR(err); 435 } 436 437 static int ovl_set_upper_acl(struct ovl_fs *ofs, struct dentry *upperdentry, 438 const char *acl_name, struct posix_acl *acl) 439 { 440 if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl) 441 return 0; 442 443 return ovl_do_set_acl(ofs, upperdentry, acl_name, acl); 444 } 445 446 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode, 447 struct ovl_cattr *cattr) 448 { 449 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 450 struct dentry *workdir = ovl_workdir(dentry); 451 struct inode *wdir = workdir->d_inode; 452 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 453 struct inode *udir = upperdir->d_inode; 454 struct dentry *upper; 455 struct dentry *newdentry; 456 int err; 457 struct posix_acl *acl, *default_acl; 458 bool hardlink = !!cattr->hardlink; 459 460 if (WARN_ON(!workdir)) 461 return -EROFS; 462 463 if (!hardlink) { 464 err = posix_acl_create(dentry->d_parent->d_inode, 465 &cattr->mode, &default_acl, &acl); 466 if (err) 467 return err; 468 } 469 470 err = ovl_lock_rename_workdir(workdir, upperdir); 471 if (err) 472 goto out; 473 474 upper = ovl_lookup_upper(ofs, dentry->d_name.name, upperdir, 475 dentry->d_name.len); 476 err = PTR_ERR(upper); 477 if (IS_ERR(upper)) 478 goto out_unlock; 479 480 err = -ESTALE; 481 if (d_is_negative(upper) || !IS_WHITEOUT(d_inode(upper))) 482 goto out_dput; 483 484 newdentry = ovl_create_temp(ofs, workdir, cattr); 485 err = PTR_ERR(newdentry); 486 if (IS_ERR(newdentry)) 487 goto out_dput; 488 489 /* 490 * mode could have been mutilated due to umask (e.g. sgid directory) 491 */ 492 if (!hardlink && 493 !S_ISLNK(cattr->mode) && 494 newdentry->d_inode->i_mode != cattr->mode) { 495 struct iattr attr = { 496 .ia_valid = ATTR_MODE, 497 .ia_mode = cattr->mode, 498 }; 499 inode_lock(newdentry->d_inode); 500 err = ovl_do_notify_change(ofs, newdentry, &attr); 501 inode_unlock(newdentry->d_inode); 502 if (err) 503 goto out_cleanup; 504 } 505 if (!hardlink) { 506 err = ovl_set_upper_acl(ofs, newdentry, 507 XATTR_NAME_POSIX_ACL_ACCESS, acl); 508 if (err) 509 goto out_cleanup; 510 511 err = ovl_set_upper_acl(ofs, newdentry, 512 XATTR_NAME_POSIX_ACL_DEFAULT, default_acl); 513 if (err) 514 goto out_cleanup; 515 } 516 517 if (!hardlink && S_ISDIR(cattr->mode)) { 518 err = ovl_set_opaque(dentry, newdentry); 519 if (err) 520 goto out_cleanup; 521 522 err = ovl_do_rename(ofs, wdir, newdentry, udir, upper, 523 RENAME_EXCHANGE); 524 if (err) 525 goto out_cleanup; 526 527 ovl_cleanup(ofs, wdir, upper); 528 } else { 529 err = ovl_do_rename(ofs, wdir, newdentry, udir, upper, 0); 530 if (err) 531 goto out_cleanup; 532 } 533 err = ovl_instantiate(dentry, inode, newdentry, hardlink); 534 if (err) { 535 ovl_cleanup(ofs, udir, newdentry); 536 dput(newdentry); 537 } 538 out_dput: 539 dput(upper); 540 out_unlock: 541 unlock_rename(workdir, upperdir); 542 out: 543 if (!hardlink) { 544 posix_acl_release(acl); 545 posix_acl_release(default_acl); 546 } 547 return err; 548 549 out_cleanup: 550 ovl_cleanup(ofs, wdir, newdentry); 551 dput(newdentry); 552 goto out_dput; 553 } 554 555 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, 556 struct ovl_cattr *attr, bool origin) 557 { 558 int err; 559 const struct cred *old_cred; 560 struct cred *override_cred; 561 struct dentry *parent = dentry->d_parent; 562 563 err = ovl_copy_up(parent); 564 if (err) 565 return err; 566 567 old_cred = ovl_override_creds(dentry->d_sb); 568 569 /* 570 * When linking a file with copy up origin into a new parent, mark the 571 * new parent dir "impure". 572 */ 573 if (origin) { 574 err = ovl_set_impure(parent, ovl_dentry_upper(parent)); 575 if (err) 576 goto out_revert_creds; 577 } 578 579 err = -ENOMEM; 580 override_cred = prepare_creds(); 581 if (override_cred) { 582 override_cred->fsuid = inode->i_uid; 583 override_cred->fsgid = inode->i_gid; 584 if (!attr->hardlink) { 585 err = security_dentry_create_files_as(dentry, 586 attr->mode, &dentry->d_name, old_cred, 587 override_cred); 588 if (err) { 589 put_cred(override_cred); 590 goto out_revert_creds; 591 } 592 } 593 put_cred(override_creds(override_cred)); 594 put_cred(override_cred); 595 596 if (!ovl_dentry_is_whiteout(dentry)) 597 err = ovl_create_upper(dentry, inode, attr); 598 else 599 err = ovl_create_over_whiteout(dentry, inode, attr); 600 } 601 out_revert_creds: 602 revert_creds(old_cred); 603 return err; 604 } 605 606 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev, 607 const char *link) 608 { 609 int err; 610 struct inode *inode; 611 struct ovl_cattr attr = { 612 .rdev = rdev, 613 .link = link, 614 }; 615 616 err = ovl_want_write(dentry); 617 if (err) 618 goto out; 619 620 /* Preallocate inode to be used by ovl_get_inode() */ 621 err = -ENOMEM; 622 inode = ovl_new_inode(dentry->d_sb, mode, rdev); 623 if (!inode) 624 goto out_drop_write; 625 626 spin_lock(&inode->i_lock); 627 inode->i_state |= I_CREATING; 628 spin_unlock(&inode->i_lock); 629 630 inode_init_owner(&init_user_ns, inode, dentry->d_parent->d_inode, mode); 631 attr.mode = inode->i_mode; 632 633 err = ovl_create_or_link(dentry, inode, &attr, false); 634 /* Did we end up using the preallocated inode? */ 635 if (inode != d_inode(dentry)) 636 iput(inode); 637 638 out_drop_write: 639 ovl_drop_write(dentry); 640 out: 641 return err; 642 } 643 644 static int ovl_create(struct user_namespace *mnt_userns, struct inode *dir, 645 struct dentry *dentry, umode_t mode, bool excl) 646 { 647 return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL); 648 } 649 650 static int ovl_mkdir(struct user_namespace *mnt_userns, struct inode *dir, 651 struct dentry *dentry, umode_t mode) 652 { 653 return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL); 654 } 655 656 static int ovl_mknod(struct user_namespace *mnt_userns, struct inode *dir, 657 struct dentry *dentry, umode_t mode, dev_t rdev) 658 { 659 /* Don't allow creation of "whiteout" on overlay */ 660 if (S_ISCHR(mode) && rdev == WHITEOUT_DEV) 661 return -EPERM; 662 663 return ovl_create_object(dentry, mode, rdev, NULL); 664 } 665 666 static int ovl_symlink(struct user_namespace *mnt_userns, struct inode *dir, 667 struct dentry *dentry, const char *link) 668 { 669 return ovl_create_object(dentry, S_IFLNK, 0, link); 670 } 671 672 static int ovl_set_link_redirect(struct dentry *dentry) 673 { 674 const struct cred *old_cred; 675 int err; 676 677 old_cred = ovl_override_creds(dentry->d_sb); 678 err = ovl_set_redirect(dentry, false); 679 revert_creds(old_cred); 680 681 return err; 682 } 683 684 static int ovl_link(struct dentry *old, struct inode *newdir, 685 struct dentry *new) 686 { 687 int err; 688 struct inode *inode; 689 690 err = ovl_want_write(old); 691 if (err) 692 goto out; 693 694 err = ovl_copy_up(old); 695 if (err) 696 goto out_drop_write; 697 698 err = ovl_copy_up(new->d_parent); 699 if (err) 700 goto out_drop_write; 701 702 if (ovl_is_metacopy_dentry(old)) { 703 err = ovl_set_link_redirect(old); 704 if (err) 705 goto out_drop_write; 706 } 707 708 err = ovl_nlink_start(old); 709 if (err) 710 goto out_drop_write; 711 712 inode = d_inode(old); 713 ihold(inode); 714 715 err = ovl_create_or_link(new, inode, 716 &(struct ovl_cattr) {.hardlink = ovl_dentry_upper(old)}, 717 ovl_type_origin(old)); 718 if (err) 719 iput(inode); 720 721 ovl_nlink_end(old); 722 out_drop_write: 723 ovl_drop_write(old); 724 out: 725 return err; 726 } 727 728 static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper) 729 { 730 return d_inode(ovl_dentry_upper(dentry)) == d_inode(upper); 731 } 732 733 static int ovl_remove_and_whiteout(struct dentry *dentry, 734 struct list_head *list) 735 { 736 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 737 struct dentry *workdir = ovl_workdir(dentry); 738 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 739 struct dentry *upper; 740 struct dentry *opaquedir = NULL; 741 int err; 742 743 if (WARN_ON(!workdir)) 744 return -EROFS; 745 746 if (!list_empty(list)) { 747 opaquedir = ovl_clear_empty(dentry, list); 748 err = PTR_ERR(opaquedir); 749 if (IS_ERR(opaquedir)) 750 goto out; 751 } 752 753 err = ovl_lock_rename_workdir(workdir, upperdir); 754 if (err) 755 goto out_dput; 756 757 upper = ovl_lookup_upper(ofs, dentry->d_name.name, upperdir, 758 dentry->d_name.len); 759 err = PTR_ERR(upper); 760 if (IS_ERR(upper)) 761 goto out_unlock; 762 763 err = -ESTALE; 764 if ((opaquedir && upper != opaquedir) || 765 (!opaquedir && ovl_dentry_upper(dentry) && 766 !ovl_matches_upper(dentry, upper))) { 767 goto out_dput_upper; 768 } 769 770 err = ovl_cleanup_and_whiteout(ofs, d_inode(upperdir), upper); 771 if (err) 772 goto out_d_drop; 773 774 ovl_dir_modified(dentry->d_parent, true); 775 out_d_drop: 776 d_drop(dentry); 777 out_dput_upper: 778 dput(upper); 779 out_unlock: 780 unlock_rename(workdir, upperdir); 781 out_dput: 782 dput(opaquedir); 783 out: 784 return err; 785 } 786 787 static int ovl_remove_upper(struct dentry *dentry, bool is_dir, 788 struct list_head *list) 789 { 790 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 791 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 792 struct inode *dir = upperdir->d_inode; 793 struct dentry *upper; 794 struct dentry *opaquedir = NULL; 795 int err; 796 797 if (!list_empty(list)) { 798 opaquedir = ovl_clear_empty(dentry, list); 799 err = PTR_ERR(opaquedir); 800 if (IS_ERR(opaquedir)) 801 goto out; 802 } 803 804 inode_lock_nested(dir, I_MUTEX_PARENT); 805 upper = ovl_lookup_upper(ofs, dentry->d_name.name, upperdir, 806 dentry->d_name.len); 807 err = PTR_ERR(upper); 808 if (IS_ERR(upper)) 809 goto out_unlock; 810 811 err = -ESTALE; 812 if ((opaquedir && upper != opaquedir) || 813 (!opaquedir && !ovl_matches_upper(dentry, upper))) 814 goto out_dput_upper; 815 816 if (is_dir) 817 err = ovl_do_rmdir(ofs, dir, upper); 818 else 819 err = ovl_do_unlink(ofs, dir, upper); 820 ovl_dir_modified(dentry->d_parent, ovl_type_origin(dentry)); 821 822 /* 823 * Keeping this dentry hashed would mean having to release 824 * upperpath/lowerpath, which could only be done if we are the 825 * sole user of this dentry. Too tricky... Just unhash for 826 * now. 827 */ 828 if (!err) 829 d_drop(dentry); 830 out_dput_upper: 831 dput(upper); 832 out_unlock: 833 inode_unlock(dir); 834 dput(opaquedir); 835 out: 836 return err; 837 } 838 839 static bool ovl_pure_upper(struct dentry *dentry) 840 { 841 return !ovl_dentry_lower(dentry) && 842 !ovl_test_flag(OVL_WHITEOUTS, d_inode(dentry)); 843 } 844 845 static void ovl_drop_nlink(struct dentry *dentry) 846 { 847 struct inode *inode = d_inode(dentry); 848 struct dentry *alias; 849 850 /* Try to find another, hashed alias */ 851 spin_lock(&inode->i_lock); 852 hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { 853 if (alias != dentry && !d_unhashed(alias)) 854 break; 855 } 856 spin_unlock(&inode->i_lock); 857 858 /* 859 * Changes to underlying layers may cause i_nlink to lose sync with 860 * reality. In this case prevent the link count from going to zero 861 * prematurely. 862 */ 863 if (inode->i_nlink > !!alias) 864 drop_nlink(inode); 865 } 866 867 static int ovl_do_remove(struct dentry *dentry, bool is_dir) 868 { 869 int err; 870 const struct cred *old_cred; 871 bool lower_positive = ovl_lower_positive(dentry); 872 LIST_HEAD(list); 873 874 /* No need to clean pure upper removed by vfs_rmdir() */ 875 if (is_dir && (lower_positive || !ovl_pure_upper(dentry))) { 876 err = ovl_check_empty_dir(dentry, &list); 877 if (err) 878 goto out; 879 } 880 881 err = ovl_want_write(dentry); 882 if (err) 883 goto out; 884 885 err = ovl_copy_up(dentry->d_parent); 886 if (err) 887 goto out_drop_write; 888 889 err = ovl_nlink_start(dentry); 890 if (err) 891 goto out_drop_write; 892 893 old_cred = ovl_override_creds(dentry->d_sb); 894 if (!lower_positive) 895 err = ovl_remove_upper(dentry, is_dir, &list); 896 else 897 err = ovl_remove_and_whiteout(dentry, &list); 898 revert_creds(old_cred); 899 if (!err) { 900 if (is_dir) 901 clear_nlink(dentry->d_inode); 902 else 903 ovl_drop_nlink(dentry); 904 } 905 ovl_nlink_end(dentry); 906 907 /* 908 * Copy ctime 909 * 910 * Note: we fail to update ctime if there was no copy-up, only a 911 * whiteout 912 */ 913 if (ovl_dentry_upper(dentry)) 914 ovl_copyattr(d_inode(dentry)); 915 916 out_drop_write: 917 ovl_drop_write(dentry); 918 out: 919 ovl_cache_free(&list); 920 return err; 921 } 922 923 static int ovl_unlink(struct inode *dir, struct dentry *dentry) 924 { 925 return ovl_do_remove(dentry, false); 926 } 927 928 static int ovl_rmdir(struct inode *dir, struct dentry *dentry) 929 { 930 return ovl_do_remove(dentry, true); 931 } 932 933 static bool ovl_type_merge_or_lower(struct dentry *dentry) 934 { 935 enum ovl_path_type type = ovl_path_type(dentry); 936 937 return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type); 938 } 939 940 static bool ovl_can_move(struct dentry *dentry) 941 { 942 return ovl_redirect_dir(dentry->d_sb) || 943 !d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry); 944 } 945 946 static char *ovl_get_redirect(struct dentry *dentry, bool abs_redirect) 947 { 948 char *buf, *ret; 949 struct dentry *d, *tmp; 950 int buflen = ovl_redirect_max + 1; 951 952 if (!abs_redirect) { 953 ret = kstrndup(dentry->d_name.name, dentry->d_name.len, 954 GFP_KERNEL); 955 goto out; 956 } 957 958 buf = ret = kmalloc(buflen, GFP_KERNEL); 959 if (!buf) 960 goto out; 961 962 buflen--; 963 buf[buflen] = '\0'; 964 for (d = dget(dentry); !IS_ROOT(d);) { 965 const char *name; 966 int thislen; 967 968 spin_lock(&d->d_lock); 969 name = ovl_dentry_get_redirect(d); 970 if (name) { 971 thislen = strlen(name); 972 } else { 973 name = d->d_name.name; 974 thislen = d->d_name.len; 975 } 976 977 /* If path is too long, fall back to userspace move */ 978 if (thislen + (name[0] != '/') > buflen) { 979 ret = ERR_PTR(-EXDEV); 980 spin_unlock(&d->d_lock); 981 goto out_put; 982 } 983 984 buflen -= thislen; 985 memcpy(&buf[buflen], name, thislen); 986 spin_unlock(&d->d_lock); 987 tmp = dget_parent(d); 988 989 dput(d); 990 d = tmp; 991 992 /* Absolute redirect: finished */ 993 if (buf[buflen] == '/') 994 break; 995 buflen--; 996 buf[buflen] = '/'; 997 } 998 ret = kstrdup(&buf[buflen], GFP_KERNEL); 999 out_put: 1000 dput(d); 1001 kfree(buf); 1002 out: 1003 return ret ? ret : ERR_PTR(-ENOMEM); 1004 } 1005 1006 static bool ovl_need_absolute_redirect(struct dentry *dentry, bool samedir) 1007 { 1008 struct dentry *lowerdentry; 1009 1010 if (!samedir) 1011 return true; 1012 1013 if (d_is_dir(dentry)) 1014 return false; 1015 1016 /* 1017 * For non-dir hardlinked files, we need absolute redirects 1018 * in general as two upper hardlinks could be in different 1019 * dirs. We could put a relative redirect now and convert 1020 * it to absolute redirect later. But when nlink > 1 and 1021 * indexing is on, that means relative redirect needs to be 1022 * converted to absolute during copy up of another lower 1023 * hardllink as well. 1024 * 1025 * So without optimizing too much, just check if lower is 1026 * a hard link or not. If lower is hard link, put absolute 1027 * redirect. 1028 */ 1029 lowerdentry = ovl_dentry_lower(dentry); 1030 return (d_inode(lowerdentry)->i_nlink > 1); 1031 } 1032 1033 static int ovl_set_redirect(struct dentry *dentry, bool samedir) 1034 { 1035 int err; 1036 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 1037 const char *redirect = ovl_dentry_get_redirect(dentry); 1038 bool absolute_redirect = ovl_need_absolute_redirect(dentry, samedir); 1039 1040 if (redirect && (!absolute_redirect || redirect[0] == '/')) 1041 return 0; 1042 1043 redirect = ovl_get_redirect(dentry, absolute_redirect); 1044 if (IS_ERR(redirect)) 1045 return PTR_ERR(redirect); 1046 1047 err = ovl_check_setxattr(ofs, ovl_dentry_upper(dentry), 1048 OVL_XATTR_REDIRECT, 1049 redirect, strlen(redirect), -EXDEV); 1050 if (!err) { 1051 spin_lock(&dentry->d_lock); 1052 ovl_dentry_set_redirect(dentry, redirect); 1053 spin_unlock(&dentry->d_lock); 1054 } else { 1055 kfree(redirect); 1056 pr_warn_ratelimited("failed to set redirect (%i)\n", 1057 err); 1058 /* Fall back to userspace copy-up */ 1059 err = -EXDEV; 1060 } 1061 return err; 1062 } 1063 1064 static int ovl_rename(struct user_namespace *mnt_userns, struct inode *olddir, 1065 struct dentry *old, struct inode *newdir, 1066 struct dentry *new, unsigned int flags) 1067 { 1068 int err; 1069 struct dentry *old_upperdir; 1070 struct dentry *new_upperdir; 1071 struct dentry *olddentry; 1072 struct dentry *newdentry; 1073 struct dentry *trap; 1074 bool old_opaque; 1075 bool new_opaque; 1076 bool cleanup_whiteout = false; 1077 bool update_nlink = false; 1078 bool overwrite = !(flags & RENAME_EXCHANGE); 1079 bool is_dir = d_is_dir(old); 1080 bool new_is_dir = d_is_dir(new); 1081 bool samedir = olddir == newdir; 1082 struct dentry *opaquedir = NULL; 1083 const struct cred *old_cred = NULL; 1084 struct ovl_fs *ofs = OVL_FS(old->d_sb); 1085 LIST_HEAD(list); 1086 1087 err = -EINVAL; 1088 if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE)) 1089 goto out; 1090 1091 flags &= ~RENAME_NOREPLACE; 1092 1093 /* Don't copy up directory trees */ 1094 err = -EXDEV; 1095 if (!ovl_can_move(old)) 1096 goto out; 1097 if (!overwrite && !ovl_can_move(new)) 1098 goto out; 1099 1100 if (overwrite && new_is_dir && !ovl_pure_upper(new)) { 1101 err = ovl_check_empty_dir(new, &list); 1102 if (err) 1103 goto out; 1104 } 1105 1106 if (overwrite) { 1107 if (ovl_lower_positive(old)) { 1108 if (!ovl_dentry_is_whiteout(new)) { 1109 /* Whiteout source */ 1110 flags |= RENAME_WHITEOUT; 1111 } else { 1112 /* Switch whiteouts */ 1113 flags |= RENAME_EXCHANGE; 1114 } 1115 } else if (is_dir && ovl_dentry_is_whiteout(new)) { 1116 flags |= RENAME_EXCHANGE; 1117 cleanup_whiteout = true; 1118 } 1119 } 1120 1121 err = ovl_want_write(old); 1122 if (err) 1123 goto out; 1124 1125 err = ovl_copy_up(old); 1126 if (err) 1127 goto out_drop_write; 1128 1129 err = ovl_copy_up(new->d_parent); 1130 if (err) 1131 goto out_drop_write; 1132 if (!overwrite) { 1133 err = ovl_copy_up(new); 1134 if (err) 1135 goto out_drop_write; 1136 } else if (d_inode(new)) { 1137 err = ovl_nlink_start(new); 1138 if (err) 1139 goto out_drop_write; 1140 1141 update_nlink = true; 1142 } 1143 1144 old_cred = ovl_override_creds(old->d_sb); 1145 1146 if (!list_empty(&list)) { 1147 opaquedir = ovl_clear_empty(new, &list); 1148 err = PTR_ERR(opaquedir); 1149 if (IS_ERR(opaquedir)) { 1150 opaquedir = NULL; 1151 goto out_revert_creds; 1152 } 1153 } 1154 1155 old_upperdir = ovl_dentry_upper(old->d_parent); 1156 new_upperdir = ovl_dentry_upper(new->d_parent); 1157 1158 if (!samedir) { 1159 /* 1160 * When moving a merge dir or non-dir with copy up origin into 1161 * a new parent, we are marking the new parent dir "impure". 1162 * When ovl_iterate() iterates an "impure" upper dir, it will 1163 * lookup the origin inodes of the entries to fill d_ino. 1164 */ 1165 if (ovl_type_origin(old)) { 1166 err = ovl_set_impure(new->d_parent, new_upperdir); 1167 if (err) 1168 goto out_revert_creds; 1169 } 1170 if (!overwrite && ovl_type_origin(new)) { 1171 err = ovl_set_impure(old->d_parent, old_upperdir); 1172 if (err) 1173 goto out_revert_creds; 1174 } 1175 } 1176 1177 trap = lock_rename(new_upperdir, old_upperdir); 1178 1179 olddentry = ovl_lookup_upper(ofs, old->d_name.name, old_upperdir, 1180 old->d_name.len); 1181 err = PTR_ERR(olddentry); 1182 if (IS_ERR(olddentry)) 1183 goto out_unlock; 1184 1185 err = -ESTALE; 1186 if (!ovl_matches_upper(old, olddentry)) 1187 goto out_dput_old; 1188 1189 newdentry = ovl_lookup_upper(ofs, new->d_name.name, new_upperdir, 1190 new->d_name.len); 1191 err = PTR_ERR(newdentry); 1192 if (IS_ERR(newdentry)) 1193 goto out_dput_old; 1194 1195 old_opaque = ovl_dentry_is_opaque(old); 1196 new_opaque = ovl_dentry_is_opaque(new); 1197 1198 err = -ESTALE; 1199 if (d_inode(new) && ovl_dentry_upper(new)) { 1200 if (opaquedir) { 1201 if (newdentry != opaquedir) 1202 goto out_dput; 1203 } else { 1204 if (!ovl_matches_upper(new, newdentry)) 1205 goto out_dput; 1206 } 1207 } else { 1208 if (!d_is_negative(newdentry)) { 1209 if (!new_opaque || !ovl_is_whiteout(newdentry)) 1210 goto out_dput; 1211 } else { 1212 if (flags & RENAME_EXCHANGE) 1213 goto out_dput; 1214 } 1215 } 1216 1217 if (olddentry == trap) 1218 goto out_dput; 1219 if (newdentry == trap) 1220 goto out_dput; 1221 1222 if (olddentry->d_inode == newdentry->d_inode) 1223 goto out_dput; 1224 1225 err = 0; 1226 if (ovl_type_merge_or_lower(old)) 1227 err = ovl_set_redirect(old, samedir); 1228 else if (is_dir && !old_opaque && ovl_type_merge(new->d_parent)) 1229 err = ovl_set_opaque_xerr(old, olddentry, -EXDEV); 1230 if (err) 1231 goto out_dput; 1232 1233 if (!overwrite && ovl_type_merge_or_lower(new)) 1234 err = ovl_set_redirect(new, samedir); 1235 else if (!overwrite && new_is_dir && !new_opaque && 1236 ovl_type_merge(old->d_parent)) 1237 err = ovl_set_opaque_xerr(new, newdentry, -EXDEV); 1238 if (err) 1239 goto out_dput; 1240 1241 err = ovl_do_rename(ofs, old_upperdir->d_inode, olddentry, 1242 new_upperdir->d_inode, newdentry, flags); 1243 if (err) 1244 goto out_dput; 1245 1246 if (cleanup_whiteout) 1247 ovl_cleanup(ofs, old_upperdir->d_inode, newdentry); 1248 1249 if (overwrite && d_inode(new)) { 1250 if (new_is_dir) 1251 clear_nlink(d_inode(new)); 1252 else 1253 ovl_drop_nlink(new); 1254 } 1255 1256 ovl_dir_modified(old->d_parent, ovl_type_origin(old) || 1257 (!overwrite && ovl_type_origin(new))); 1258 ovl_dir_modified(new->d_parent, ovl_type_origin(old) || 1259 (d_inode(new) && ovl_type_origin(new))); 1260 1261 /* copy ctime: */ 1262 ovl_copyattr(d_inode(old)); 1263 if (d_inode(new) && ovl_dentry_upper(new)) 1264 ovl_copyattr(d_inode(new)); 1265 1266 out_dput: 1267 dput(newdentry); 1268 out_dput_old: 1269 dput(olddentry); 1270 out_unlock: 1271 unlock_rename(new_upperdir, old_upperdir); 1272 out_revert_creds: 1273 revert_creds(old_cred); 1274 if (update_nlink) 1275 ovl_nlink_end(new); 1276 out_drop_write: 1277 ovl_drop_write(old); 1278 out: 1279 dput(opaquedir); 1280 ovl_cache_free(&list); 1281 return err; 1282 } 1283 1284 const struct inode_operations ovl_dir_inode_operations = { 1285 .lookup = ovl_lookup, 1286 .mkdir = ovl_mkdir, 1287 .symlink = ovl_symlink, 1288 .unlink = ovl_unlink, 1289 .rmdir = ovl_rmdir, 1290 .rename = ovl_rename, 1291 .link = ovl_link, 1292 .setattr = ovl_setattr, 1293 .create = ovl_create, 1294 .mknod = ovl_mknod, 1295 .permission = ovl_permission, 1296 .getattr = ovl_getattr, 1297 .listxattr = ovl_listxattr, 1298 .get_inode_acl = ovl_get_inode_acl, 1299 .get_acl = ovl_get_acl, 1300 .set_acl = ovl_set_acl, 1301 .update_time = ovl_update_time, 1302 .fileattr_get = ovl_fileattr_get, 1303 .fileattr_set = ovl_fileattr_set, 1304 }; 1305