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, upper, 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 *name, const struct posix_acl *acl) 439 { 440 void *buffer; 441 size_t size; 442 int err; 443 444 if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl) 445 return 0; 446 447 size = posix_acl_xattr_size(acl->a_count); 448 buffer = kmalloc(size, GFP_KERNEL); 449 if (!buffer) 450 return -ENOMEM; 451 452 err = posix_acl_to_xattr(&init_user_ns, acl, buffer, size); 453 if (err < 0) 454 goto out_free; 455 456 err = ovl_do_setxattr(ofs, upperdentry, name, buffer, size, XATTR_CREATE); 457 out_free: 458 kfree(buffer); 459 return err; 460 } 461 462 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode, 463 struct ovl_cattr *cattr) 464 { 465 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 466 struct dentry *workdir = ovl_workdir(dentry); 467 struct inode *wdir = workdir->d_inode; 468 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 469 struct inode *udir = upperdir->d_inode; 470 struct dentry *upper; 471 struct dentry *newdentry; 472 int err; 473 struct posix_acl *acl, *default_acl; 474 bool hardlink = !!cattr->hardlink; 475 476 if (WARN_ON(!workdir)) 477 return -EROFS; 478 479 if (!hardlink) { 480 err = posix_acl_create(dentry->d_parent->d_inode, 481 &cattr->mode, &default_acl, &acl); 482 if (err) 483 return err; 484 } 485 486 err = ovl_lock_rename_workdir(workdir, upperdir); 487 if (err) 488 goto out; 489 490 upper = ovl_lookup_upper(ofs, dentry->d_name.name, upperdir, 491 dentry->d_name.len); 492 err = PTR_ERR(upper); 493 if (IS_ERR(upper)) 494 goto out_unlock; 495 496 err = -ESTALE; 497 if (d_is_negative(upper) || !IS_WHITEOUT(d_inode(upper))) 498 goto out_dput; 499 500 newdentry = ovl_create_temp(ofs, workdir, cattr); 501 err = PTR_ERR(newdentry); 502 if (IS_ERR(newdentry)) 503 goto out_dput; 504 505 /* 506 * mode could have been mutilated due to umask (e.g. sgid directory) 507 */ 508 if (!hardlink && 509 !S_ISLNK(cattr->mode) && 510 newdentry->d_inode->i_mode != cattr->mode) { 511 struct iattr attr = { 512 .ia_valid = ATTR_MODE, 513 .ia_mode = cattr->mode, 514 }; 515 inode_lock(newdentry->d_inode); 516 err = ovl_do_notify_change(ofs, newdentry, &attr); 517 inode_unlock(newdentry->d_inode); 518 if (err) 519 goto out_cleanup; 520 } 521 if (!hardlink) { 522 err = ovl_set_upper_acl(ofs, newdentry, 523 XATTR_NAME_POSIX_ACL_ACCESS, acl); 524 if (err) 525 goto out_cleanup; 526 527 err = ovl_set_upper_acl(ofs, newdentry, 528 XATTR_NAME_POSIX_ACL_DEFAULT, default_acl); 529 if (err) 530 goto out_cleanup; 531 } 532 533 if (!hardlink && S_ISDIR(cattr->mode)) { 534 err = ovl_set_opaque(dentry, newdentry); 535 if (err) 536 goto out_cleanup; 537 538 err = ovl_do_rename(ofs, wdir, newdentry, udir, upper, 539 RENAME_EXCHANGE); 540 if (err) 541 goto out_cleanup; 542 543 ovl_cleanup(ofs, wdir, upper); 544 } else { 545 err = ovl_do_rename(ofs, wdir, newdentry, udir, upper, 0); 546 if (err) 547 goto out_cleanup; 548 } 549 err = ovl_instantiate(dentry, inode, newdentry, hardlink); 550 if (err) { 551 ovl_cleanup(ofs, udir, newdentry); 552 dput(newdentry); 553 } 554 out_dput: 555 dput(upper); 556 out_unlock: 557 unlock_rename(workdir, upperdir); 558 out: 559 if (!hardlink) { 560 posix_acl_release(acl); 561 posix_acl_release(default_acl); 562 } 563 return err; 564 565 out_cleanup: 566 ovl_cleanup(ofs, wdir, newdentry); 567 dput(newdentry); 568 goto out_dput; 569 } 570 571 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, 572 struct ovl_cattr *attr, bool origin) 573 { 574 int err; 575 const struct cred *old_cred; 576 struct cred *override_cred; 577 struct dentry *parent = dentry->d_parent; 578 579 err = ovl_copy_up(parent); 580 if (err) 581 return err; 582 583 old_cred = ovl_override_creds(dentry->d_sb); 584 585 /* 586 * When linking a file with copy up origin into a new parent, mark the 587 * new parent dir "impure". 588 */ 589 if (origin) { 590 err = ovl_set_impure(parent, ovl_dentry_upper(parent)); 591 if (err) 592 goto out_revert_creds; 593 } 594 595 err = -ENOMEM; 596 override_cred = prepare_creds(); 597 if (override_cred) { 598 override_cred->fsuid = inode->i_uid; 599 override_cred->fsgid = inode->i_gid; 600 if (!attr->hardlink) { 601 err = security_dentry_create_files_as(dentry, 602 attr->mode, &dentry->d_name, old_cred, 603 override_cred); 604 if (err) { 605 put_cred(override_cred); 606 goto out_revert_creds; 607 } 608 } 609 put_cred(override_creds(override_cred)); 610 put_cred(override_cred); 611 612 if (!ovl_dentry_is_whiteout(dentry)) 613 err = ovl_create_upper(dentry, inode, attr); 614 else 615 err = ovl_create_over_whiteout(dentry, inode, attr); 616 } 617 out_revert_creds: 618 revert_creds(old_cred); 619 return err; 620 } 621 622 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev, 623 const char *link) 624 { 625 int err; 626 struct inode *inode; 627 struct ovl_cattr attr = { 628 .rdev = rdev, 629 .link = link, 630 }; 631 632 err = ovl_want_write(dentry); 633 if (err) 634 goto out; 635 636 /* Preallocate inode to be used by ovl_get_inode() */ 637 err = -ENOMEM; 638 inode = ovl_new_inode(dentry->d_sb, mode, rdev); 639 if (!inode) 640 goto out_drop_write; 641 642 spin_lock(&inode->i_lock); 643 inode->i_state |= I_CREATING; 644 spin_unlock(&inode->i_lock); 645 646 inode_init_owner(&init_user_ns, inode, dentry->d_parent->d_inode, mode); 647 attr.mode = inode->i_mode; 648 649 err = ovl_create_or_link(dentry, inode, &attr, false); 650 /* Did we end up using the preallocated inode? */ 651 if (inode != d_inode(dentry)) 652 iput(inode); 653 654 out_drop_write: 655 ovl_drop_write(dentry); 656 out: 657 return err; 658 } 659 660 static int ovl_create(struct user_namespace *mnt_userns, struct inode *dir, 661 struct dentry *dentry, umode_t mode, bool excl) 662 { 663 return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL); 664 } 665 666 static int ovl_mkdir(struct user_namespace *mnt_userns, struct inode *dir, 667 struct dentry *dentry, umode_t mode) 668 { 669 return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL); 670 } 671 672 static int ovl_mknod(struct user_namespace *mnt_userns, struct inode *dir, 673 struct dentry *dentry, umode_t mode, dev_t rdev) 674 { 675 /* Don't allow creation of "whiteout" on overlay */ 676 if (S_ISCHR(mode) && rdev == WHITEOUT_DEV) 677 return -EPERM; 678 679 return ovl_create_object(dentry, mode, rdev, NULL); 680 } 681 682 static int ovl_symlink(struct user_namespace *mnt_userns, struct inode *dir, 683 struct dentry *dentry, const char *link) 684 { 685 return ovl_create_object(dentry, S_IFLNK, 0, link); 686 } 687 688 static int ovl_set_link_redirect(struct dentry *dentry) 689 { 690 const struct cred *old_cred; 691 int err; 692 693 old_cred = ovl_override_creds(dentry->d_sb); 694 err = ovl_set_redirect(dentry, false); 695 revert_creds(old_cred); 696 697 return err; 698 } 699 700 static int ovl_link(struct dentry *old, struct inode *newdir, 701 struct dentry *new) 702 { 703 int err; 704 struct inode *inode; 705 706 err = ovl_want_write(old); 707 if (err) 708 goto out; 709 710 err = ovl_copy_up(old); 711 if (err) 712 goto out_drop_write; 713 714 err = ovl_copy_up(new->d_parent); 715 if (err) 716 goto out_drop_write; 717 718 if (ovl_is_metacopy_dentry(old)) { 719 err = ovl_set_link_redirect(old); 720 if (err) 721 goto out_drop_write; 722 } 723 724 err = ovl_nlink_start(old); 725 if (err) 726 goto out_drop_write; 727 728 inode = d_inode(old); 729 ihold(inode); 730 731 err = ovl_create_or_link(new, inode, 732 &(struct ovl_cattr) {.hardlink = ovl_dentry_upper(old)}, 733 ovl_type_origin(old)); 734 if (err) 735 iput(inode); 736 737 ovl_nlink_end(old); 738 out_drop_write: 739 ovl_drop_write(old); 740 out: 741 return err; 742 } 743 744 static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper) 745 { 746 return d_inode(ovl_dentry_upper(dentry)) == d_inode(upper); 747 } 748 749 static int ovl_remove_and_whiteout(struct dentry *dentry, 750 struct list_head *list) 751 { 752 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 753 struct dentry *workdir = ovl_workdir(dentry); 754 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 755 struct dentry *upper; 756 struct dentry *opaquedir = NULL; 757 int err; 758 759 if (WARN_ON(!workdir)) 760 return -EROFS; 761 762 if (!list_empty(list)) { 763 opaquedir = ovl_clear_empty(dentry, list); 764 err = PTR_ERR(opaquedir); 765 if (IS_ERR(opaquedir)) 766 goto out; 767 } 768 769 err = ovl_lock_rename_workdir(workdir, upperdir); 770 if (err) 771 goto out_dput; 772 773 upper = ovl_lookup_upper(ofs, dentry->d_name.name, upperdir, 774 dentry->d_name.len); 775 err = PTR_ERR(upper); 776 if (IS_ERR(upper)) 777 goto out_unlock; 778 779 err = -ESTALE; 780 if ((opaquedir && upper != opaquedir) || 781 (!opaquedir && ovl_dentry_upper(dentry) && 782 !ovl_matches_upper(dentry, upper))) { 783 goto out_dput_upper; 784 } 785 786 err = ovl_cleanup_and_whiteout(ofs, d_inode(upperdir), upper); 787 if (err) 788 goto out_d_drop; 789 790 ovl_dir_modified(dentry->d_parent, true); 791 out_d_drop: 792 d_drop(dentry); 793 out_dput_upper: 794 dput(upper); 795 out_unlock: 796 unlock_rename(workdir, upperdir); 797 out_dput: 798 dput(opaquedir); 799 out: 800 return err; 801 } 802 803 static int ovl_remove_upper(struct dentry *dentry, bool is_dir, 804 struct list_head *list) 805 { 806 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 807 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 808 struct inode *dir = upperdir->d_inode; 809 struct dentry *upper; 810 struct dentry *opaquedir = NULL; 811 int err; 812 813 if (!list_empty(list)) { 814 opaquedir = ovl_clear_empty(dentry, list); 815 err = PTR_ERR(opaquedir); 816 if (IS_ERR(opaquedir)) 817 goto out; 818 } 819 820 inode_lock_nested(dir, I_MUTEX_PARENT); 821 upper = ovl_lookup_upper(ofs, dentry->d_name.name, upperdir, 822 dentry->d_name.len); 823 err = PTR_ERR(upper); 824 if (IS_ERR(upper)) 825 goto out_unlock; 826 827 err = -ESTALE; 828 if ((opaquedir && upper != opaquedir) || 829 (!opaquedir && !ovl_matches_upper(dentry, upper))) 830 goto out_dput_upper; 831 832 if (is_dir) 833 err = ovl_do_rmdir(ofs, dir, upper); 834 else 835 err = ovl_do_unlink(ofs, dir, upper); 836 ovl_dir_modified(dentry->d_parent, ovl_type_origin(dentry)); 837 838 /* 839 * Keeping this dentry hashed would mean having to release 840 * upperpath/lowerpath, which could only be done if we are the 841 * sole user of this dentry. Too tricky... Just unhash for 842 * now. 843 */ 844 if (!err) 845 d_drop(dentry); 846 out_dput_upper: 847 dput(upper); 848 out_unlock: 849 inode_unlock(dir); 850 dput(opaquedir); 851 out: 852 return err; 853 } 854 855 static bool ovl_pure_upper(struct dentry *dentry) 856 { 857 return !ovl_dentry_lower(dentry) && 858 !ovl_test_flag(OVL_WHITEOUTS, d_inode(dentry)); 859 } 860 861 static void ovl_drop_nlink(struct dentry *dentry) 862 { 863 struct inode *inode = d_inode(dentry); 864 struct dentry *alias; 865 866 /* Try to find another, hashed alias */ 867 spin_lock(&inode->i_lock); 868 hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { 869 if (alias != dentry && !d_unhashed(alias)) 870 break; 871 } 872 spin_unlock(&inode->i_lock); 873 874 /* 875 * Changes to underlying layers may cause i_nlink to lose sync with 876 * reality. In this case prevent the link count from going to zero 877 * prematurely. 878 */ 879 if (inode->i_nlink > !!alias) 880 drop_nlink(inode); 881 } 882 883 static int ovl_do_remove(struct dentry *dentry, bool is_dir) 884 { 885 int err; 886 const struct cred *old_cred; 887 struct dentry *upperdentry; 888 bool lower_positive = ovl_lower_positive(dentry); 889 LIST_HEAD(list); 890 891 /* No need to clean pure upper removed by vfs_rmdir() */ 892 if (is_dir && (lower_positive || !ovl_pure_upper(dentry))) { 893 err = ovl_check_empty_dir(dentry, &list); 894 if (err) 895 goto out; 896 } 897 898 err = ovl_want_write(dentry); 899 if (err) 900 goto out; 901 902 err = ovl_copy_up(dentry->d_parent); 903 if (err) 904 goto out_drop_write; 905 906 err = ovl_nlink_start(dentry); 907 if (err) 908 goto out_drop_write; 909 910 old_cred = ovl_override_creds(dentry->d_sb); 911 if (!lower_positive) 912 err = ovl_remove_upper(dentry, is_dir, &list); 913 else 914 err = ovl_remove_and_whiteout(dentry, &list); 915 revert_creds(old_cred); 916 if (!err) { 917 if (is_dir) 918 clear_nlink(dentry->d_inode); 919 else 920 ovl_drop_nlink(dentry); 921 } 922 ovl_nlink_end(dentry); 923 924 /* 925 * Copy ctime 926 * 927 * Note: we fail to update ctime if there was no copy-up, only a 928 * whiteout 929 */ 930 upperdentry = ovl_dentry_upper(dentry); 931 if (upperdentry) 932 ovl_copyattr(d_inode(upperdentry), d_inode(dentry)); 933 934 out_drop_write: 935 ovl_drop_write(dentry); 936 out: 937 ovl_cache_free(&list); 938 return err; 939 } 940 941 static int ovl_unlink(struct inode *dir, struct dentry *dentry) 942 { 943 return ovl_do_remove(dentry, false); 944 } 945 946 static int ovl_rmdir(struct inode *dir, struct dentry *dentry) 947 { 948 return ovl_do_remove(dentry, true); 949 } 950 951 static bool ovl_type_merge_or_lower(struct dentry *dentry) 952 { 953 enum ovl_path_type type = ovl_path_type(dentry); 954 955 return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type); 956 } 957 958 static bool ovl_can_move(struct dentry *dentry) 959 { 960 return ovl_redirect_dir(dentry->d_sb) || 961 !d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry); 962 } 963 964 static char *ovl_get_redirect(struct dentry *dentry, bool abs_redirect) 965 { 966 char *buf, *ret; 967 struct dentry *d, *tmp; 968 int buflen = ovl_redirect_max + 1; 969 970 if (!abs_redirect) { 971 ret = kstrndup(dentry->d_name.name, dentry->d_name.len, 972 GFP_KERNEL); 973 goto out; 974 } 975 976 buf = ret = kmalloc(buflen, GFP_KERNEL); 977 if (!buf) 978 goto out; 979 980 buflen--; 981 buf[buflen] = '\0'; 982 for (d = dget(dentry); !IS_ROOT(d);) { 983 const char *name; 984 int thislen; 985 986 spin_lock(&d->d_lock); 987 name = ovl_dentry_get_redirect(d); 988 if (name) { 989 thislen = strlen(name); 990 } else { 991 name = d->d_name.name; 992 thislen = d->d_name.len; 993 } 994 995 /* If path is too long, fall back to userspace move */ 996 if (thislen + (name[0] != '/') > buflen) { 997 ret = ERR_PTR(-EXDEV); 998 spin_unlock(&d->d_lock); 999 goto out_put; 1000 } 1001 1002 buflen -= thislen; 1003 memcpy(&buf[buflen], name, thislen); 1004 spin_unlock(&d->d_lock); 1005 tmp = dget_parent(d); 1006 1007 dput(d); 1008 d = tmp; 1009 1010 /* Absolute redirect: finished */ 1011 if (buf[buflen] == '/') 1012 break; 1013 buflen--; 1014 buf[buflen] = '/'; 1015 } 1016 ret = kstrdup(&buf[buflen], GFP_KERNEL); 1017 out_put: 1018 dput(d); 1019 kfree(buf); 1020 out: 1021 return ret ? ret : ERR_PTR(-ENOMEM); 1022 } 1023 1024 static bool ovl_need_absolute_redirect(struct dentry *dentry, bool samedir) 1025 { 1026 struct dentry *lowerdentry; 1027 1028 if (!samedir) 1029 return true; 1030 1031 if (d_is_dir(dentry)) 1032 return false; 1033 1034 /* 1035 * For non-dir hardlinked files, we need absolute redirects 1036 * in general as two upper hardlinks could be in different 1037 * dirs. We could put a relative redirect now and convert 1038 * it to absolute redirect later. But when nlink > 1 and 1039 * indexing is on, that means relative redirect needs to be 1040 * converted to absolute during copy up of another lower 1041 * hardllink as well. 1042 * 1043 * So without optimizing too much, just check if lower is 1044 * a hard link or not. If lower is hard link, put absolute 1045 * redirect. 1046 */ 1047 lowerdentry = ovl_dentry_lower(dentry); 1048 return (d_inode(lowerdentry)->i_nlink > 1); 1049 } 1050 1051 static int ovl_set_redirect(struct dentry *dentry, bool samedir) 1052 { 1053 int err; 1054 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 1055 const char *redirect = ovl_dentry_get_redirect(dentry); 1056 bool absolute_redirect = ovl_need_absolute_redirect(dentry, samedir); 1057 1058 if (redirect && (!absolute_redirect || redirect[0] == '/')) 1059 return 0; 1060 1061 redirect = ovl_get_redirect(dentry, absolute_redirect); 1062 if (IS_ERR(redirect)) 1063 return PTR_ERR(redirect); 1064 1065 err = ovl_check_setxattr(ofs, ovl_dentry_upper(dentry), 1066 OVL_XATTR_REDIRECT, 1067 redirect, strlen(redirect), -EXDEV); 1068 if (!err) { 1069 spin_lock(&dentry->d_lock); 1070 ovl_dentry_set_redirect(dentry, redirect); 1071 spin_unlock(&dentry->d_lock); 1072 } else { 1073 kfree(redirect); 1074 pr_warn_ratelimited("failed to set redirect (%i)\n", 1075 err); 1076 /* Fall back to userspace copy-up */ 1077 err = -EXDEV; 1078 } 1079 return err; 1080 } 1081 1082 static int ovl_rename(struct user_namespace *mnt_userns, struct inode *olddir, 1083 struct dentry *old, struct inode *newdir, 1084 struct dentry *new, unsigned int flags) 1085 { 1086 int err; 1087 struct dentry *old_upperdir; 1088 struct dentry *new_upperdir; 1089 struct dentry *olddentry; 1090 struct dentry *newdentry; 1091 struct dentry *trap; 1092 bool old_opaque; 1093 bool new_opaque; 1094 bool cleanup_whiteout = false; 1095 bool update_nlink = false; 1096 bool overwrite = !(flags & RENAME_EXCHANGE); 1097 bool is_dir = d_is_dir(old); 1098 bool new_is_dir = d_is_dir(new); 1099 bool samedir = olddir == newdir; 1100 struct dentry *opaquedir = NULL; 1101 const struct cred *old_cred = NULL; 1102 struct ovl_fs *ofs = OVL_FS(old->d_sb); 1103 LIST_HEAD(list); 1104 1105 err = -EINVAL; 1106 if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE)) 1107 goto out; 1108 1109 flags &= ~RENAME_NOREPLACE; 1110 1111 /* Don't copy up directory trees */ 1112 err = -EXDEV; 1113 if (!ovl_can_move(old)) 1114 goto out; 1115 if (!overwrite && !ovl_can_move(new)) 1116 goto out; 1117 1118 if (overwrite && new_is_dir && !ovl_pure_upper(new)) { 1119 err = ovl_check_empty_dir(new, &list); 1120 if (err) 1121 goto out; 1122 } 1123 1124 if (overwrite) { 1125 if (ovl_lower_positive(old)) { 1126 if (!ovl_dentry_is_whiteout(new)) { 1127 /* Whiteout source */ 1128 flags |= RENAME_WHITEOUT; 1129 } else { 1130 /* Switch whiteouts */ 1131 flags |= RENAME_EXCHANGE; 1132 } 1133 } else if (is_dir && ovl_dentry_is_whiteout(new)) { 1134 flags |= RENAME_EXCHANGE; 1135 cleanup_whiteout = true; 1136 } 1137 } 1138 1139 err = ovl_want_write(old); 1140 if (err) 1141 goto out; 1142 1143 err = ovl_copy_up(old); 1144 if (err) 1145 goto out_drop_write; 1146 1147 err = ovl_copy_up(new->d_parent); 1148 if (err) 1149 goto out_drop_write; 1150 if (!overwrite) { 1151 err = ovl_copy_up(new); 1152 if (err) 1153 goto out_drop_write; 1154 } else if (d_inode(new)) { 1155 err = ovl_nlink_start(new); 1156 if (err) 1157 goto out_drop_write; 1158 1159 update_nlink = true; 1160 } 1161 1162 old_cred = ovl_override_creds(old->d_sb); 1163 1164 if (!list_empty(&list)) { 1165 opaquedir = ovl_clear_empty(new, &list); 1166 err = PTR_ERR(opaquedir); 1167 if (IS_ERR(opaquedir)) { 1168 opaquedir = NULL; 1169 goto out_revert_creds; 1170 } 1171 } 1172 1173 old_upperdir = ovl_dentry_upper(old->d_parent); 1174 new_upperdir = ovl_dentry_upper(new->d_parent); 1175 1176 if (!samedir) { 1177 /* 1178 * When moving a merge dir or non-dir with copy up origin into 1179 * a new parent, we are marking the new parent dir "impure". 1180 * When ovl_iterate() iterates an "impure" upper dir, it will 1181 * lookup the origin inodes of the entries to fill d_ino. 1182 */ 1183 if (ovl_type_origin(old)) { 1184 err = ovl_set_impure(new->d_parent, new_upperdir); 1185 if (err) 1186 goto out_revert_creds; 1187 } 1188 if (!overwrite && ovl_type_origin(new)) { 1189 err = ovl_set_impure(old->d_parent, old_upperdir); 1190 if (err) 1191 goto out_revert_creds; 1192 } 1193 } 1194 1195 trap = lock_rename(new_upperdir, old_upperdir); 1196 1197 olddentry = ovl_lookup_upper(ofs, old->d_name.name, old_upperdir, 1198 old->d_name.len); 1199 err = PTR_ERR(olddentry); 1200 if (IS_ERR(olddentry)) 1201 goto out_unlock; 1202 1203 err = -ESTALE; 1204 if (!ovl_matches_upper(old, olddentry)) 1205 goto out_dput_old; 1206 1207 newdentry = ovl_lookup_upper(ofs, new->d_name.name, new_upperdir, 1208 new->d_name.len); 1209 err = PTR_ERR(newdentry); 1210 if (IS_ERR(newdentry)) 1211 goto out_dput_old; 1212 1213 old_opaque = ovl_dentry_is_opaque(old); 1214 new_opaque = ovl_dentry_is_opaque(new); 1215 1216 err = -ESTALE; 1217 if (d_inode(new) && ovl_dentry_upper(new)) { 1218 if (opaquedir) { 1219 if (newdentry != opaquedir) 1220 goto out_dput; 1221 } else { 1222 if (!ovl_matches_upper(new, newdentry)) 1223 goto out_dput; 1224 } 1225 } else { 1226 if (!d_is_negative(newdentry)) { 1227 if (!new_opaque || !ovl_is_whiteout(newdentry)) 1228 goto out_dput; 1229 } else { 1230 if (flags & RENAME_EXCHANGE) 1231 goto out_dput; 1232 } 1233 } 1234 1235 if (olddentry == trap) 1236 goto out_dput; 1237 if (newdentry == trap) 1238 goto out_dput; 1239 1240 if (olddentry->d_inode == newdentry->d_inode) 1241 goto out_dput; 1242 1243 err = 0; 1244 if (ovl_type_merge_or_lower(old)) 1245 err = ovl_set_redirect(old, samedir); 1246 else if (is_dir && !old_opaque && ovl_type_merge(new->d_parent)) 1247 err = ovl_set_opaque_xerr(old, olddentry, -EXDEV); 1248 if (err) 1249 goto out_dput; 1250 1251 if (!overwrite && ovl_type_merge_or_lower(new)) 1252 err = ovl_set_redirect(new, samedir); 1253 else if (!overwrite && new_is_dir && !new_opaque && 1254 ovl_type_merge(old->d_parent)) 1255 err = ovl_set_opaque_xerr(new, newdentry, -EXDEV); 1256 if (err) 1257 goto out_dput; 1258 1259 err = ovl_do_rename(ofs, old_upperdir->d_inode, olddentry, 1260 new_upperdir->d_inode, newdentry, flags); 1261 if (err) 1262 goto out_dput; 1263 1264 if (cleanup_whiteout) 1265 ovl_cleanup(ofs, old_upperdir->d_inode, newdentry); 1266 1267 if (overwrite && d_inode(new)) { 1268 if (new_is_dir) 1269 clear_nlink(d_inode(new)); 1270 else 1271 ovl_drop_nlink(new); 1272 } 1273 1274 ovl_dir_modified(old->d_parent, ovl_type_origin(old) || 1275 (!overwrite && ovl_type_origin(new))); 1276 ovl_dir_modified(new->d_parent, ovl_type_origin(old) || 1277 (d_inode(new) && ovl_type_origin(new))); 1278 1279 /* copy ctime: */ 1280 ovl_copyattr(d_inode(olddentry), d_inode(old)); 1281 if (d_inode(new) && ovl_dentry_upper(new)) 1282 ovl_copyattr(d_inode(newdentry), d_inode(new)); 1283 1284 out_dput: 1285 dput(newdentry); 1286 out_dput_old: 1287 dput(olddentry); 1288 out_unlock: 1289 unlock_rename(new_upperdir, old_upperdir); 1290 out_revert_creds: 1291 revert_creds(old_cred); 1292 if (update_nlink) 1293 ovl_nlink_end(new); 1294 out_drop_write: 1295 ovl_drop_write(old); 1296 out: 1297 dput(opaquedir); 1298 ovl_cache_free(&list); 1299 return err; 1300 } 1301 1302 const struct inode_operations ovl_dir_inode_operations = { 1303 .lookup = ovl_lookup, 1304 .mkdir = ovl_mkdir, 1305 .symlink = ovl_symlink, 1306 .unlink = ovl_unlink, 1307 .rmdir = ovl_rmdir, 1308 .rename = ovl_rename, 1309 .link = ovl_link, 1310 .setattr = ovl_setattr, 1311 .create = ovl_create, 1312 .mknod = ovl_mknod, 1313 .permission = ovl_permission, 1314 .getattr = ovl_getattr, 1315 .listxattr = ovl_listxattr, 1316 .get_acl = ovl_get_acl, 1317 .update_time = ovl_update_time, 1318 .fileattr_get = ovl_fileattr_get, 1319 .fileattr_set = ovl_fileattr_set, 1320 }; 1321