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 19static unsigned short ovl_redirect_max = 256; 20module_param_named(redirect_max, ovl_redirect_max, ushort, 0644); 21MODULE_PARM_DESC(redirect_max, 22 "Maximum length of absolute redirect xattr value"); 23 24static int ovl_set_redirect(struct dentry *dentry, bool samedir); 25 26int ovl_cleanup(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(wdir, wdentry); 33 else 34 err = ovl_do_unlink(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 45struct dentry *ovl_lookup_temp(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 = lookup_one_len(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 */ 65static 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(workdir); 74 if (IS_ERR(whiteout)) 75 goto out; 76 77 err = ovl_do_whiteout(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(workdir); 88 if (IS_ERR(whiteout)) 89 goto out; 90 91 err = ovl_do_link(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; 104out: 105 return whiteout; 106} 107 108/* Caller must hold i_mutex on both workdir and dir */ 109int 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(wdir, whiteout, dir, dentry, flags); 126 if (err) 127 goto kill_whiteout; 128 if (flags) 129 ovl_cleanup(wdir, dentry); 130 131out: 132 dput(whiteout); 133 return err; 134 135kill_whiteout: 136 ovl_cleanup(wdir, whiteout); 137 goto out; 138} 139 140int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry, umode_t mode) 141{ 142 int err; 143 struct dentry *d, *dentry = *newdentry; 144 145 err = ovl_do_mkdir(dir, dentry, mode); 146 if (err) 147 return err; 148 149 if (likely(!d_unhashed(dentry))) 150 return 0; 151 152 /* 153 * vfs_mkdir() may succeed and leave the dentry passed 154 * to it unhashed and negative. If that happens, try to 155 * lookup a new hashed and positive dentry. 156 */ 157 d = lookup_one_len(dentry->d_name.name, dentry->d_parent, 158 dentry->d_name.len); 159 if (IS_ERR(d)) { 160 pr_warn("failed lookup after mkdir (%pd2, err=%i).\n", 161 dentry, err); 162 return PTR_ERR(d); 163 } 164 dput(dentry); 165 *newdentry = d; 166 167 return 0; 168} 169 170struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry, 171 struct ovl_cattr *attr) 172{ 173 int err; 174 175 if (IS_ERR(newdentry)) 176 return newdentry; 177 178 err = -ESTALE; 179 if (newdentry->d_inode) 180 goto out; 181 182 if (attr->hardlink) { 183 err = ovl_do_link(attr->hardlink, dir, newdentry); 184 } else { 185 switch (attr->mode & S_IFMT) { 186 case S_IFREG: 187 err = ovl_do_create(dir, newdentry, attr->mode); 188 break; 189 190 case S_IFDIR: 191 /* mkdir is special... */ 192 err = ovl_mkdir_real(dir, &newdentry, attr->mode); 193 break; 194 195 case S_IFCHR: 196 case S_IFBLK: 197 case S_IFIFO: 198 case S_IFSOCK: 199 err = ovl_do_mknod(dir, newdentry, attr->mode, 200 attr->rdev); 201 break; 202 203 case S_IFLNK: 204 err = ovl_do_symlink(dir, newdentry, attr->link); 205 break; 206 207 default: 208 err = -EPERM; 209 } 210 } 211 if (!err && WARN_ON(!newdentry->d_inode)) { 212 /* 213 * Not quite sure if non-instantiated dentry is legal or not. 214 * VFS doesn't seem to care so check and warn here. 215 */ 216 err = -EIO; 217 } 218out: 219 if (err) { 220 dput(newdentry); 221 return ERR_PTR(err); 222 } 223 return newdentry; 224} 225 226struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr) 227{ 228 return ovl_create_real(d_inode(workdir), ovl_lookup_temp(workdir), 229 attr); 230} 231 232static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper, 233 int xerr) 234{ 235 int err; 236 237 err = ovl_check_setxattr(dentry, upper, OVL_XATTR_OPAQUE, "y", 1, xerr); 238 if (!err) 239 ovl_dentry_set_opaque(dentry); 240 241 return err; 242} 243 244static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry) 245{ 246 /* 247 * Fail with -EIO when trying to create opaque dir and upper doesn't 248 * support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to 249 * return a specific error for noxattr case. 250 */ 251 return ovl_set_opaque_xerr(dentry, upperdentry, -EIO); 252} 253 254/* 255 * Common operations required to be done after creation of file on upper. 256 * If @hardlink is false, then @inode is a pre-allocated inode, we may or 257 * may not use to instantiate the new dentry. 258 */ 259static int ovl_instantiate(struct dentry *dentry, struct inode *inode, 260 struct dentry *newdentry, bool hardlink) 261{ 262 struct ovl_inode_params oip = { 263 .upperdentry = newdentry, 264 .newinode = inode, 265 }; 266 267 ovl_dir_modified(dentry->d_parent, false); 268 ovl_dentry_set_upper_alias(dentry); 269 ovl_dentry_init_reval(dentry, newdentry); 270 271 if (!hardlink) { 272 /* 273 * ovl_obtain_alias() can be called after ovl_create_real() 274 * and before we get here, so we may get an inode from cache 275 * with the same real upperdentry that is not the inode we 276 * pre-allocated. In this case we will use the cached inode 277 * to instantiate the new dentry. 278 * 279 * XXX: if we ever use ovl_obtain_alias() to decode directory 280 * file handles, need to use ovl_get_inode_locked() and 281 * d_instantiate_new() here to prevent from creating two 282 * hashed directory inode aliases. 283 */ 284 inode = ovl_get_inode(dentry->d_sb, &oip); 285 if (IS_ERR(inode)) 286 return PTR_ERR(inode); 287 if (inode == oip.newinode) 288 ovl_set_flag(OVL_UPPERDATA, inode); 289 } else { 290 WARN_ON(ovl_inode_real(inode) != d_inode(newdentry)); 291 dput(newdentry); 292 inc_nlink(inode); 293 } 294 295 d_instantiate(dentry, inode); 296 if (inode != oip.newinode) { 297 pr_warn_ratelimited("newly created inode found in cache (%pd2)\n", 298 dentry); 299 } 300 301 /* Force lookup of new upper hardlink to find its lower */ 302 if (hardlink) 303 d_drop(dentry); 304 305 return 0; 306} 307 308static bool ovl_type_merge(struct dentry *dentry) 309{ 310 return OVL_TYPE_MERGE(ovl_path_type(dentry)); 311} 312 313static bool ovl_type_origin(struct dentry *dentry) 314{ 315 return OVL_TYPE_ORIGIN(ovl_path_type(dentry)); 316} 317 318static int ovl_create_upper(struct dentry *dentry, struct inode *inode, 319 struct ovl_cattr *attr) 320{ 321 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 322 struct inode *udir = upperdir->d_inode; 323 struct dentry *newdentry; 324 int err; 325 326 if (!attr->hardlink && !IS_POSIXACL(udir)) 327 attr->mode &= ~current_umask(); 328 329 inode_lock_nested(udir, I_MUTEX_PARENT); 330 newdentry = ovl_create_real(udir, 331 lookup_one_len(dentry->d_name.name, 332 upperdir, 333 dentry->d_name.len), 334 attr); 335 err = PTR_ERR(newdentry); 336 if (IS_ERR(newdentry)) 337 goto out_unlock; 338 339 if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry)) { 340 /* Setting opaque here is just an optimization, allow to fail */ 341 ovl_set_opaque(dentry, newdentry); 342 } 343 344 err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink); 345 if (err) 346 goto out_cleanup; 347out_unlock: 348 inode_unlock(udir); 349 return err; 350 351out_cleanup: 352 ovl_cleanup(udir, newdentry); 353 dput(newdentry); 354 goto out_unlock; 355} 356 357static struct dentry *ovl_clear_empty(struct dentry *dentry, 358 struct list_head *list) 359{ 360 struct dentry *workdir = ovl_workdir(dentry); 361 struct inode *wdir = workdir->d_inode; 362 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 363 struct inode *udir = upperdir->d_inode; 364 struct path upperpath; 365 struct dentry *upper; 366 struct dentry *opaquedir; 367 struct kstat stat; 368 int err; 369 370 if (WARN_ON(!workdir)) 371 return ERR_PTR(-EROFS); 372 373 err = ovl_lock_rename_workdir(workdir, upperdir); 374 if (err) 375 goto out; 376 377 ovl_path_upper(dentry, &upperpath); 378 err = vfs_getattr(&upperpath, &stat, 379 STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT); 380 if (err) 381 goto out_unlock; 382 383 err = -ESTALE; 384 if (!S_ISDIR(stat.mode)) 385 goto out_unlock; 386 upper = upperpath.dentry; 387 if (upper->d_parent->d_inode != udir) 388 goto out_unlock; 389 390 opaquedir = ovl_create_temp(workdir, OVL_CATTR(stat.mode)); 391 err = PTR_ERR(opaquedir); 392 if (IS_ERR(opaquedir)) 393 goto out_unlock; 394 395 err = ovl_copy_xattr(dentry->d_sb, upper, opaquedir); 396 if (err) 397 goto out_cleanup; 398 399 err = ovl_set_opaque(dentry, opaquedir); 400 if (err) 401 goto out_cleanup; 402 403 inode_lock(opaquedir->d_inode); 404 err = ovl_set_attr(opaquedir, &stat); 405 inode_unlock(opaquedir->d_inode); 406 if (err) 407 goto out_cleanup; 408 409 err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE); 410 if (err) 411 goto out_cleanup; 412 413 ovl_cleanup_whiteouts(upper, list); 414 ovl_cleanup(wdir, upper); 415 unlock_rename(workdir, upperdir); 416 417 /* dentry's upper doesn't match now, get rid of it */ 418 d_drop(dentry); 419 420 return opaquedir; 421 422out_cleanup: 423 ovl_cleanup(wdir, opaquedir); 424 dput(opaquedir); 425out_unlock: 426 unlock_rename(workdir, upperdir); 427out: 428 return ERR_PTR(err); 429} 430 431static int ovl_set_upper_acl(struct dentry *upperdentry, const char *name, 432 const struct posix_acl *acl) 433{ 434 void *buffer; 435 size_t size; 436 int err; 437 438 if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl) 439 return 0; 440 441 size = posix_acl_xattr_size(acl->a_count); 442 buffer = kmalloc(size, GFP_KERNEL); 443 if (!buffer) 444 return -ENOMEM; 445 446 err = posix_acl_to_xattr(&init_user_ns, acl, buffer, size); 447 if (err < 0) 448 goto out_free; 449 450 err = vfs_setxattr(upperdentry, name, buffer, size, XATTR_CREATE); 451out_free: 452 kfree(buffer); 453 return err; 454} 455 456static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode, 457 struct ovl_cattr *cattr) 458{ 459 struct dentry *workdir = ovl_workdir(dentry); 460 struct inode *wdir = workdir->d_inode; 461 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 462 struct inode *udir = upperdir->d_inode; 463 struct dentry *upper; 464 struct dentry *newdentry; 465 int err; 466 struct posix_acl *acl, *default_acl; 467 bool hardlink = !!cattr->hardlink; 468 469 if (WARN_ON(!workdir)) 470 return -EROFS; 471 472 if (!hardlink) { 473 err = posix_acl_create(dentry->d_parent->d_inode, 474 &cattr->mode, &default_acl, &acl); 475 if (err) 476 return err; 477 } 478 479 err = ovl_lock_rename_workdir(workdir, upperdir); 480 if (err) 481 goto out; 482 483 upper = lookup_one_len(dentry->d_name.name, upperdir, 484 dentry->d_name.len); 485 err = PTR_ERR(upper); 486 if (IS_ERR(upper)) 487 goto out_unlock; 488 489 err = -ESTALE; 490 if (d_is_negative(upper) || !IS_WHITEOUT(d_inode(upper))) 491 goto out_dput; 492 493 newdentry = ovl_create_temp(workdir, cattr); 494 err = PTR_ERR(newdentry); 495 if (IS_ERR(newdentry)) 496 goto out_dput; 497 498 /* 499 * mode could have been mutilated due to umask (e.g. sgid directory) 500 */ 501 if (!hardlink && 502 !S_ISLNK(cattr->mode) && 503 newdentry->d_inode->i_mode != cattr->mode) { 504 struct iattr attr = { 505 .ia_valid = ATTR_MODE, 506 .ia_mode = cattr->mode, 507 }; 508 inode_lock(newdentry->d_inode); 509 err = notify_change(newdentry, &attr, NULL); 510 inode_unlock(newdentry->d_inode); 511 if (err) 512 goto out_cleanup; 513 } 514 if (!hardlink) { 515 err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_ACCESS, 516 acl); 517 if (err) 518 goto out_cleanup; 519 520 err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_DEFAULT, 521 default_acl); 522 if (err) 523 goto out_cleanup; 524 } 525 526 if (!hardlink && S_ISDIR(cattr->mode)) { 527 err = ovl_set_opaque(dentry, newdentry); 528 if (err) 529 goto out_cleanup; 530 531 err = ovl_do_rename(wdir, newdentry, udir, upper, 532 RENAME_EXCHANGE); 533 if (err) 534 goto out_cleanup; 535 536 ovl_cleanup(wdir, upper); 537 } else { 538 err = ovl_do_rename(wdir, newdentry, udir, upper, 0); 539 if (err) 540 goto out_cleanup; 541 } 542 err = ovl_instantiate(dentry, inode, newdentry, hardlink); 543 if (err) { 544 ovl_cleanup(udir, newdentry); 545 dput(newdentry); 546 } 547out_dput: 548 dput(upper); 549out_unlock: 550 unlock_rename(workdir, upperdir); 551out: 552 if (!hardlink) { 553 posix_acl_release(acl); 554 posix_acl_release(default_acl); 555 } 556 return err; 557 558out_cleanup: 559 ovl_cleanup(wdir, newdentry); 560 dput(newdentry); 561 goto out_dput; 562} 563 564static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, 565 struct ovl_cattr *attr, bool origin) 566{ 567 int err; 568 const struct cred *old_cred; 569 struct cred *override_cred; 570 struct dentry *parent = dentry->d_parent; 571 572 err = ovl_copy_up(parent); 573 if (err) 574 return err; 575 576 old_cred = ovl_override_creds(dentry->d_sb); 577 578 /* 579 * When linking a file with copy up origin into a new parent, mark the 580 * new parent dir "impure". 581 */ 582 if (origin) { 583 err = ovl_set_impure(parent, ovl_dentry_upper(parent)); 584 if (err) 585 goto out_revert_creds; 586 } 587 588 if (!attr->hardlink) { 589 err = -ENOMEM; 590 override_cred = prepare_creds(); 591 if (!override_cred) 592 goto out_revert_creds; 593 /* 594 * In the creation cases(create, mkdir, mknod, symlink), 595 * ovl should transfer current's fs{u,g}id to underlying 596 * fs. Because underlying fs want to initialize its new 597 * inode owner using current's fs{u,g}id. And in this 598 * case, the @inode is a new inode that is initialized 599 * in inode_init_owner() to current's fs{u,g}id. So use 600 * the inode's i_{u,g}id to override the cred's fs{u,g}id. 601 * 602 * But in the other hardlink case, ovl_link() does not 603 * create a new inode, so just use the ovl mounter's 604 * fs{u,g}id. 605 */ 606 override_cred->fsuid = inode->i_uid; 607 override_cred->fsgid = inode->i_gid; 608 err = security_dentry_create_files_as(dentry, 609 attr->mode, &dentry->d_name, old_cred, 610 override_cred); 611 if (err) { 612 put_cred(override_cred); 613 goto out_revert_creds; 614 } 615 put_cred(override_creds(override_cred)); 616 put_cred(override_cred); 617 } 618 619 if (!ovl_dentry_is_whiteout(dentry)) 620 err = ovl_create_upper(dentry, inode, attr); 621 else 622 err = ovl_create_over_whiteout(dentry, inode, attr); 623 624out_revert_creds: 625 revert_creds(old_cred); 626 return err; 627} 628 629static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev, 630 const char *link) 631{ 632 int err; 633 struct inode *inode; 634 struct ovl_cattr attr = { 635 .rdev = rdev, 636 .link = link, 637 }; 638 639 err = ovl_want_write(dentry); 640 if (err) 641 goto out; 642 643 /* Preallocate inode to be used by ovl_get_inode() */ 644 err = -ENOMEM; 645 inode = ovl_new_inode(dentry->d_sb, mode, rdev); 646 if (!inode) 647 goto out_drop_write; 648 649 spin_lock(&inode->i_lock); 650 inode->i_state |= I_CREATING; 651 spin_unlock(&inode->i_lock); 652 653 inode_init_owner(inode, dentry->d_parent->d_inode, mode); 654 attr.mode = inode->i_mode; 655 656 err = ovl_create_or_link(dentry, inode, &attr, false); 657 /* Did we end up using the preallocated inode? */ 658 if (inode != d_inode(dentry)) 659 iput(inode); 660 661out_drop_write: 662 ovl_drop_write(dentry); 663out: 664 return err; 665} 666 667static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode, 668 bool excl) 669{ 670 return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL); 671} 672 673static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 674{ 675 return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL); 676} 677 678static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, 679 dev_t rdev) 680{ 681 /* Don't allow creation of "whiteout" on overlay */ 682 if (S_ISCHR(mode) && rdev == WHITEOUT_DEV) 683 return -EPERM; 684 685 return ovl_create_object(dentry, mode, rdev, NULL); 686} 687 688static int ovl_symlink(struct inode *dir, struct dentry *dentry, 689 const char *link) 690{ 691 return ovl_create_object(dentry, S_IFLNK, 0, link); 692} 693 694static int ovl_set_link_redirect(struct dentry *dentry) 695{ 696 const struct cred *old_cred; 697 int err; 698 699 old_cred = ovl_override_creds(dentry->d_sb); 700 err = ovl_set_redirect(dentry, false); 701 revert_creds(old_cred); 702 703 return err; 704} 705 706static int ovl_link(struct dentry *old, struct inode *newdir, 707 struct dentry *new) 708{ 709 int err; 710 struct inode *inode; 711 712 err = ovl_want_write(old); 713 if (err) 714 goto out; 715 716 err = ovl_copy_up(old); 717 if (err) 718 goto out_drop_write; 719 720 err = ovl_copy_up(new->d_parent); 721 if (err) 722 goto out_drop_write; 723 724 if (ovl_is_metacopy_dentry(old)) { 725 err = ovl_set_link_redirect(old); 726 if (err) 727 goto out_drop_write; 728 } 729 730 err = ovl_nlink_start(old); 731 if (err) 732 goto out_drop_write; 733 734 inode = d_inode(old); 735 ihold(inode); 736 737 err = ovl_create_or_link(new, inode, 738 &(struct ovl_cattr) {.hardlink = ovl_dentry_upper(old)}, 739 ovl_type_origin(old)); 740 if (err) 741 iput(inode); 742 743 ovl_nlink_end(old); 744out_drop_write: 745 ovl_drop_write(old); 746out: 747 return err; 748} 749 750static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper) 751{ 752 return d_inode(ovl_dentry_upper(dentry)) == d_inode(upper); 753} 754 755static int ovl_remove_and_whiteout(struct dentry *dentry, 756 struct list_head *list) 757{ 758 struct ovl_fs *ofs = OVL_FS(dentry->d_sb); 759 struct dentry *workdir = ovl_workdir(dentry); 760 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 761 struct dentry *upper; 762 struct dentry *opaquedir = NULL; 763 int err; 764 765 if (WARN_ON(!workdir)) 766 return -EROFS; 767 768 if (!list_empty(list)) { 769 opaquedir = ovl_clear_empty(dentry, list); 770 err = PTR_ERR(opaquedir); 771 if (IS_ERR(opaquedir)) 772 goto out; 773 } 774 775 err = ovl_lock_rename_workdir(workdir, upperdir); 776 if (err) 777 goto out_dput; 778 779 upper = lookup_one_len(dentry->d_name.name, upperdir, 780 dentry->d_name.len); 781 err = PTR_ERR(upper); 782 if (IS_ERR(upper)) 783 goto out_unlock; 784 785 err = -ESTALE; 786 if ((opaquedir && upper != opaquedir) || 787 (!opaquedir && ovl_dentry_upper(dentry) && 788 !ovl_matches_upper(dentry, upper))) { 789 goto out_dput_upper; 790 } 791 792 err = ovl_cleanup_and_whiteout(ofs, d_inode(upperdir), upper); 793 if (err) 794 goto out_d_drop; 795 796 ovl_dir_modified(dentry->d_parent, true); 797out_d_drop: 798 d_drop(dentry); 799out_dput_upper: 800 dput(upper); 801out_unlock: 802 unlock_rename(workdir, upperdir); 803out_dput: 804 dput(opaquedir); 805out: 806 return err; 807} 808 809static int ovl_remove_upper(struct dentry *dentry, bool is_dir, 810 struct list_head *list) 811{ 812 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); 813 struct inode *dir = upperdir->d_inode; 814 struct dentry *upper; 815 struct dentry *opaquedir = NULL; 816 int err; 817 818 if (!list_empty(list)) { 819 opaquedir = ovl_clear_empty(dentry, list); 820 err = PTR_ERR(opaquedir); 821 if (IS_ERR(opaquedir)) 822 goto out; 823 } 824 825 inode_lock_nested(dir, I_MUTEX_PARENT); 826 upper = lookup_one_len(dentry->d_name.name, upperdir, 827 dentry->d_name.len); 828 err = PTR_ERR(upper); 829 if (IS_ERR(upper)) 830 goto out_unlock; 831 832 err = -ESTALE; 833 if ((opaquedir && upper != opaquedir) || 834 (!opaquedir && !ovl_matches_upper(dentry, upper))) 835 goto out_dput_upper; 836 837 if (is_dir) 838 err = vfs_rmdir(dir, upper); 839 else 840 err = vfs_unlink(dir, upper, NULL); 841 ovl_dir_modified(dentry->d_parent, ovl_type_origin(dentry)); 842 843 /* 844 * Keeping this dentry hashed would mean having to release 845 * upperpath/lowerpath, which could only be done if we are the 846 * sole user of this dentry. Too tricky... Just unhash for 847 * now. 848 */ 849 if (!err) 850 d_drop(dentry); 851out_dput_upper: 852 dput(upper); 853out_unlock: 854 inode_unlock(dir); 855 dput(opaquedir); 856out: 857 return err; 858} 859 860static bool ovl_pure_upper(struct dentry *dentry) 861{ 862 return !ovl_dentry_lower(dentry) && 863 !ovl_test_flag(OVL_WHITEOUTS, d_inode(dentry)); 864} 865 866static void ovl_drop_nlink(struct dentry *dentry) 867{ 868 struct inode *inode = d_inode(dentry); 869 struct dentry *alias; 870 871 /* Try to find another, hashed alias */ 872 spin_lock(&inode->i_lock); 873 hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { 874 if (alias != dentry && !d_unhashed(alias)) 875 break; 876 } 877 spin_unlock(&inode->i_lock); 878 879 /* 880 * Changes to underlying layers may cause i_nlink to lose sync with 881 * reality. In this case prevent the link count from going to zero 882 * prematurely. 883 */ 884 if (inode->i_nlink > !!alias) 885 drop_nlink(inode); 886} 887 888static int ovl_do_remove(struct dentry *dentry, bool is_dir) 889{ 890 int err; 891 const struct cred *old_cred; 892 struct dentry *upperdentry; 893 bool lower_positive = ovl_lower_positive(dentry); 894 LIST_HEAD(list); 895 896 /* No need to clean pure upper removed by vfs_rmdir() */ 897 if (is_dir && (lower_positive || !ovl_pure_upper(dentry))) { 898 err = ovl_check_empty_dir(dentry, &list); 899 if (err) 900 goto out; 901 } 902 903 err = ovl_want_write(dentry); 904 if (err) 905 goto out; 906 907 err = ovl_copy_up(dentry->d_parent); 908 if (err) 909 goto out_drop_write; 910 911 err = ovl_nlink_start(dentry); 912 if (err) 913 goto out_drop_write; 914 915 old_cred = ovl_override_creds(dentry->d_sb); 916 if (!lower_positive) 917 err = ovl_remove_upper(dentry, is_dir, &list); 918 else 919 err = ovl_remove_and_whiteout(dentry, &list); 920 revert_creds(old_cred); 921 if (!err) { 922 if (is_dir) 923 clear_nlink(dentry->d_inode); 924 else 925 ovl_drop_nlink(dentry); 926 } 927 ovl_nlink_end(dentry); 928 929 /* 930 * Copy ctime 931 * 932 * Note: we fail to update ctime if there was no copy-up, only a 933 * whiteout 934 */ 935 upperdentry = ovl_dentry_upper(dentry); 936 if (upperdentry) 937 ovl_copyattr(d_inode(upperdentry), d_inode(dentry)); 938 939out_drop_write: 940 ovl_drop_write(dentry); 941out: 942 ovl_cache_free(&list); 943 return err; 944} 945 946static int ovl_unlink(struct inode *dir, struct dentry *dentry) 947{ 948 return ovl_do_remove(dentry, false); 949} 950 951static int ovl_rmdir(struct inode *dir, struct dentry *dentry) 952{ 953 return ovl_do_remove(dentry, true); 954} 955 956static bool ovl_type_merge_or_lower(struct dentry *dentry) 957{ 958 enum ovl_path_type type = ovl_path_type(dentry); 959 960 return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type); 961} 962 963static bool ovl_can_move(struct dentry *dentry) 964{ 965 return ovl_redirect_dir(dentry->d_sb) || 966 !d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry); 967} 968 969static char *ovl_get_redirect(struct dentry *dentry, bool abs_redirect) 970{ 971 char *buf, *ret; 972 struct dentry *d, *tmp; 973 int buflen = ovl_redirect_max + 1; 974 975 if (!abs_redirect) { 976 ret = kstrndup(dentry->d_name.name, dentry->d_name.len, 977 GFP_KERNEL); 978 goto out; 979 } 980 981 buf = ret = kmalloc(buflen, GFP_KERNEL); 982 if (!buf) 983 goto out; 984 985 buflen--; 986 buf[buflen] = '\0'; 987 for (d = dget(dentry); !IS_ROOT(d);) { 988 const char *name; 989 int thislen; 990 991 spin_lock(&d->d_lock); 992 name = ovl_dentry_get_redirect(d); 993 if (name) { 994 thislen = strlen(name); 995 } else { 996 name = d->d_name.name; 997 thislen = d->d_name.len; 998 } 999 1000 /* If path is too long, fall back to userspace move */ 1001 if (thislen + (name[0] != '/') > buflen) { 1002 ret = ERR_PTR(-EXDEV); 1003 spin_unlock(&d->d_lock); 1004 goto out_put; 1005 } 1006 1007 buflen -= thislen; 1008 memcpy(&buf[buflen], name, thislen); 1009 spin_unlock(&d->d_lock); 1010 tmp = dget_parent(d); 1011 1012 dput(d); 1013 d = tmp; 1014 1015 /* Absolute redirect: finished */ 1016 if (buf[buflen] == '/') 1017 break; 1018 buflen--; 1019 buf[buflen] = '/'; 1020 } 1021 ret = kstrdup(&buf[buflen], GFP_KERNEL); 1022out_put: 1023 dput(d); 1024 kfree(buf); 1025out: 1026 return ret ? ret : ERR_PTR(-ENOMEM); 1027} 1028 1029static bool ovl_need_absolute_redirect(struct dentry *dentry, bool samedir) 1030{ 1031 struct dentry *lowerdentry; 1032 1033 if (!samedir) 1034 return true; 1035 1036 if (d_is_dir(dentry)) 1037 return false; 1038 1039 /* 1040 * For non-dir hardlinked files, we need absolute redirects 1041 * in general as two upper hardlinks could be in different 1042 * dirs. We could put a relative redirect now and convert 1043 * it to absolute redirect later. But when nlink > 1 and 1044 * indexing is on, that means relative redirect needs to be 1045 * converted to absolute during copy up of another lower 1046 * hardllink as well. 1047 * 1048 * So without optimizing too much, just check if lower is 1049 * a hard link or not. If lower is hard link, put absolute 1050 * redirect. 1051 */ 1052 lowerdentry = ovl_dentry_lower(dentry); 1053 return (d_inode(lowerdentry)->i_nlink > 1); 1054} 1055 1056static int ovl_set_redirect(struct dentry *dentry, bool samedir) 1057{ 1058 int err; 1059 const char *redirect = ovl_dentry_get_redirect(dentry); 1060 bool absolute_redirect = ovl_need_absolute_redirect(dentry, samedir); 1061 1062 if (redirect && (!absolute_redirect || redirect[0] == '/')) 1063 return 0; 1064 1065 redirect = ovl_get_redirect(dentry, absolute_redirect); 1066 if (IS_ERR(redirect)) 1067 return PTR_ERR(redirect); 1068 1069 err = ovl_check_setxattr(dentry, ovl_dentry_upper(dentry), 1070 OVL_XATTR_REDIRECT, 1071 redirect, strlen(redirect), -EXDEV); 1072 if (!err) { 1073 spin_lock(&dentry->d_lock); 1074 ovl_dentry_set_redirect(dentry, redirect); 1075 spin_unlock(&dentry->d_lock); 1076 } else { 1077 kfree(redirect); 1078 pr_warn_ratelimited("failed to set redirect (%i)\n", 1079 err); 1080 /* Fall back to userspace copy-up */ 1081 err = -EXDEV; 1082 } 1083 return err; 1084} 1085 1086static int ovl_rename(struct inode *olddir, struct dentry *old, 1087 struct inode *newdir, struct dentry *new, 1088 unsigned int flags) 1089{ 1090 int err; 1091 struct dentry *old_upperdir; 1092 struct dentry *new_upperdir; 1093 struct dentry *olddentry; 1094 struct dentry *newdentry; 1095 struct dentry *trap; 1096 bool old_opaque; 1097 bool new_opaque; 1098 bool cleanup_whiteout = false; 1099 bool update_nlink = false; 1100 bool overwrite = !(flags & RENAME_EXCHANGE); 1101 bool is_dir = d_is_dir(old); 1102 bool new_is_dir = d_is_dir(new); 1103 bool samedir = olddir == newdir; 1104 struct dentry *opaquedir = NULL; 1105 const struct cred *old_cred = NULL; 1106 LIST_HEAD(list); 1107 1108 err = -EINVAL; 1109 if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE)) 1110 goto out; 1111 1112 flags &= ~RENAME_NOREPLACE; 1113 1114 /* Don't copy up directory trees */ 1115 err = -EXDEV; 1116 if (!ovl_can_move(old)) 1117 goto out; 1118 if (!overwrite && !ovl_can_move(new)) 1119 goto out; 1120 1121 if (overwrite && new_is_dir && !ovl_pure_upper(new)) { 1122 err = ovl_check_empty_dir(new, &list); 1123 if (err) 1124 goto out; 1125 } 1126 1127 if (overwrite) { 1128 if (ovl_lower_positive(old)) { 1129 if (!ovl_dentry_is_whiteout(new)) { 1130 /* Whiteout source */ 1131 flags |= RENAME_WHITEOUT; 1132 } else { 1133 /* Switch whiteouts */ 1134 flags |= RENAME_EXCHANGE; 1135 } 1136 } else if (is_dir && ovl_dentry_is_whiteout(new)) { 1137 flags |= RENAME_EXCHANGE; 1138 cleanup_whiteout = true; 1139 } 1140 } 1141 1142 err = ovl_want_write(old); 1143 if (err) 1144 goto out; 1145 1146 err = ovl_copy_up(old); 1147 if (err) 1148 goto out_drop_write; 1149 1150 err = ovl_copy_up(new->d_parent); 1151 if (err) 1152 goto out_drop_write; 1153 if (!overwrite) { 1154 err = ovl_copy_up(new); 1155 if (err) 1156 goto out_drop_write; 1157 } else if (d_inode(new)) { 1158 err = ovl_nlink_start(new); 1159 if (err) 1160 goto out_drop_write; 1161 1162 update_nlink = true; 1163 } 1164 1165 old_cred = ovl_override_creds(old->d_sb); 1166 1167 if (!list_empty(&list)) { 1168 opaquedir = ovl_clear_empty(new, &list); 1169 err = PTR_ERR(opaquedir); 1170 if (IS_ERR(opaquedir)) { 1171 opaquedir = NULL; 1172 goto out_revert_creds; 1173 } 1174 } 1175 1176 old_upperdir = ovl_dentry_upper(old->d_parent); 1177 new_upperdir = ovl_dentry_upper(new->d_parent); 1178 1179 if (!samedir) { 1180 /* 1181 * When moving a merge dir or non-dir with copy up origin into 1182 * a new parent, we are marking the new parent dir "impure". 1183 * When ovl_iterate() iterates an "impure" upper dir, it will 1184 * lookup the origin inodes of the entries to fill d_ino. 1185 */ 1186 if (ovl_type_origin(old)) { 1187 err = ovl_set_impure(new->d_parent, new_upperdir); 1188 if (err) 1189 goto out_revert_creds; 1190 } 1191 if (!overwrite && ovl_type_origin(new)) { 1192 err = ovl_set_impure(old->d_parent, old_upperdir); 1193 if (err) 1194 goto out_revert_creds; 1195 } 1196 } 1197 1198 trap = lock_rename(new_upperdir, old_upperdir); 1199 1200 olddentry = lookup_one_len(old->d_name.name, old_upperdir, 1201 old->d_name.len); 1202 err = PTR_ERR(olddentry); 1203 if (IS_ERR(olddentry)) 1204 goto out_unlock; 1205 1206 err = -ESTALE; 1207 if (!ovl_matches_upper(old, olddentry)) 1208 goto out_dput_old; 1209 1210 newdentry = lookup_one_len(new->d_name.name, new_upperdir, 1211 new->d_name.len); 1212 err = PTR_ERR(newdentry); 1213 if (IS_ERR(newdentry)) 1214 goto out_dput_old; 1215 1216 old_opaque = ovl_dentry_is_opaque(old); 1217 new_opaque = ovl_dentry_is_opaque(new); 1218 1219 err = -ESTALE; 1220 if (d_inode(new) && ovl_dentry_upper(new)) { 1221 if (opaquedir) { 1222 if (newdentry != opaquedir) 1223 goto out_dput; 1224 } else { 1225 if (!ovl_matches_upper(new, newdentry)) 1226 goto out_dput; 1227 } 1228 } else { 1229 if (!d_is_negative(newdentry)) { 1230 if (!new_opaque || !ovl_is_whiteout(newdentry)) 1231 goto out_dput; 1232 } else { 1233 if (flags & RENAME_EXCHANGE) 1234 goto out_dput; 1235 } 1236 } 1237 1238 if (olddentry == trap) 1239 goto out_dput; 1240 if (newdentry == trap) 1241 goto out_dput; 1242 1243 if (olddentry->d_inode == newdentry->d_inode) 1244 goto out_dput; 1245 1246 err = 0; 1247 if (ovl_type_merge_or_lower(old)) 1248 err = ovl_set_redirect(old, samedir); 1249 else if (is_dir && !old_opaque && ovl_type_merge(new->d_parent)) 1250 err = ovl_set_opaque_xerr(old, olddentry, -EXDEV); 1251 if (err) 1252 goto out_dput; 1253 1254 if (!overwrite && ovl_type_merge_or_lower(new)) 1255 err = ovl_set_redirect(new, samedir); 1256 else if (!overwrite && new_is_dir && !new_opaque && 1257 ovl_type_merge(old->d_parent)) 1258 err = ovl_set_opaque_xerr(new, newdentry, -EXDEV); 1259 if (err) 1260 goto out_dput; 1261 1262 err = ovl_do_rename(old_upperdir->d_inode, olddentry, 1263 new_upperdir->d_inode, newdentry, flags); 1264 if (err) 1265 goto out_dput; 1266 1267 if (cleanup_whiteout) 1268 ovl_cleanup(old_upperdir->d_inode, newdentry); 1269 1270 if (overwrite && d_inode(new)) { 1271 if (new_is_dir) 1272 clear_nlink(d_inode(new)); 1273 else 1274 ovl_drop_nlink(new); 1275 } 1276 1277 ovl_dir_modified(old->d_parent, ovl_type_origin(old) || 1278 (!overwrite && ovl_type_origin(new))); 1279 ovl_dir_modified(new->d_parent, ovl_type_origin(old) || 1280 (d_inode(new) && ovl_type_origin(new))); 1281 1282 /* copy ctime: */ 1283 ovl_copyattr(d_inode(olddentry), d_inode(old)); 1284 if (d_inode(new) && ovl_dentry_upper(new)) 1285 ovl_copyattr(d_inode(newdentry), d_inode(new)); 1286 1287out_dput: 1288 dput(newdentry); 1289out_dput_old: 1290 dput(olddentry); 1291out_unlock: 1292 unlock_rename(new_upperdir, old_upperdir); 1293out_revert_creds: 1294 revert_creds(old_cred); 1295 if (update_nlink) 1296 ovl_nlink_end(new); 1297out_drop_write: 1298 ovl_drop_write(old); 1299out: 1300 dput(opaquedir); 1301 ovl_cache_free(&list); 1302 return err; 1303} 1304 1305const struct inode_operations ovl_dir_inode_operations = { 1306 .lookup = ovl_lookup, 1307 .mkdir = ovl_mkdir, 1308 .symlink = ovl_symlink, 1309 .unlink = ovl_unlink, 1310 .rmdir = ovl_rmdir, 1311 .rename = ovl_rename, 1312 .link = ovl_link, 1313 .setattr = ovl_setattr, 1314 .create = ovl_create, 1315 .mknod = ovl_mknod, 1316 .permission = ovl_permission, 1317 .getattr = ovl_getattr, 1318 .listxattr = ovl_listxattr, 1319 .get_acl = ovl_get_acl, 1320 .update_time = ovl_update_time, 1321}; 1322