1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * 4 * Copyright (C) 2011 Novell Inc. 5 */ 6 7 #include <uapi/linux/magic.h> 8 #include <linux/fs.h> 9 #include <linux/namei.h> 10 #include <linux/xattr.h> 11 #include <linux/mount.h> 12 #include <linux/parser.h> 13 #include <linux/module.h> 14 #include <linux/statfs.h> 15 #include <linux/seq_file.h> 16 #include <linux/posix_acl_xattr.h> 17 #include <linux/exportfs.h> 18 #include "overlayfs.h" 19 20 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); 21 MODULE_DESCRIPTION("Overlay filesystem"); 22 MODULE_LICENSE("GPL"); 23 24 25 struct ovl_dir_cache; 26 27 #define OVL_MAX_STACK 500 28 29 static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR); 30 module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644); 31 MODULE_PARM_DESC(redirect_dir, 32 "Default to on or off for the redirect_dir feature"); 33 34 static bool ovl_redirect_always_follow = 35 IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW); 36 module_param_named(redirect_always_follow, ovl_redirect_always_follow, 37 bool, 0644); 38 MODULE_PARM_DESC(redirect_always_follow, 39 "Follow redirects even if redirect_dir feature is turned off"); 40 41 static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX); 42 module_param_named(index, ovl_index_def, bool, 0644); 43 MODULE_PARM_DESC(index, 44 "Default to on or off for the inodes index feature"); 45 46 static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT); 47 module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644); 48 MODULE_PARM_DESC(nfs_export, 49 "Default to on or off for the NFS export feature"); 50 51 static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO); 52 module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644); 53 MODULE_PARM_DESC(xino_auto, 54 "Auto enable xino feature"); 55 56 static void ovl_entry_stack_free(struct ovl_entry *oe) 57 { 58 unsigned int i; 59 60 for (i = 0; i < oe->numlower; i++) 61 dput(oe->lowerstack[i].dentry); 62 } 63 64 static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY); 65 module_param_named(metacopy, ovl_metacopy_def, bool, 0644); 66 MODULE_PARM_DESC(metacopy, 67 "Default to on or off for the metadata only copy up feature"); 68 69 static void ovl_dentry_release(struct dentry *dentry) 70 { 71 struct ovl_entry *oe = dentry->d_fsdata; 72 73 if (oe) { 74 ovl_entry_stack_free(oe); 75 kfree_rcu(oe, rcu); 76 } 77 } 78 79 static struct dentry *ovl_d_real(struct dentry *dentry, 80 const struct inode *inode) 81 { 82 struct dentry *real = NULL, *lower; 83 84 /* It's an overlay file */ 85 if (inode && d_inode(dentry) == inode) 86 return dentry; 87 88 if (!d_is_reg(dentry)) { 89 if (!inode || inode == d_inode(dentry)) 90 return dentry; 91 goto bug; 92 } 93 94 real = ovl_dentry_upper(dentry); 95 if (real && (inode == d_inode(real))) 96 return real; 97 98 if (real && !inode && ovl_has_upperdata(d_inode(dentry))) 99 return real; 100 101 lower = ovl_dentry_lowerdata(dentry); 102 if (!lower) 103 goto bug; 104 real = lower; 105 106 /* Handle recursion */ 107 real = d_real(real, inode); 108 109 if (!inode || inode == d_inode(real)) 110 return real; 111 bug: 112 WARN(1, "%s(%pd4, %s:%lu): real dentry (%p/%lu) not found\n", 113 __func__, dentry, inode ? inode->i_sb->s_id : "NULL", 114 inode ? inode->i_ino : 0, real, 115 real && d_inode(real) ? d_inode(real)->i_ino : 0); 116 return dentry; 117 } 118 119 static int ovl_revalidate_real(struct dentry *d, unsigned int flags, bool weak) 120 { 121 int ret = 1; 122 123 if (weak) { 124 if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) 125 ret = d->d_op->d_weak_revalidate(d, flags); 126 } else if (d->d_flags & DCACHE_OP_REVALIDATE) { 127 ret = d->d_op->d_revalidate(d, flags); 128 if (!ret) { 129 if (!(flags & LOOKUP_RCU)) 130 d_invalidate(d); 131 ret = -ESTALE; 132 } 133 } 134 return ret; 135 } 136 137 static int ovl_dentry_revalidate_common(struct dentry *dentry, 138 unsigned int flags, bool weak) 139 { 140 struct ovl_entry *oe = dentry->d_fsdata; 141 struct dentry *upper; 142 unsigned int i; 143 int ret = 1; 144 145 upper = ovl_dentry_upper(dentry); 146 if (upper) 147 ret = ovl_revalidate_real(upper, flags, weak); 148 149 for (i = 0; ret > 0 && i < oe->numlower; i++) { 150 ret = ovl_revalidate_real(oe->lowerstack[i].dentry, flags, 151 weak); 152 } 153 return ret; 154 } 155 156 static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) 157 { 158 return ovl_dentry_revalidate_common(dentry, flags, false); 159 } 160 161 static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) 162 { 163 return ovl_dentry_revalidate_common(dentry, flags, true); 164 } 165 166 static const struct dentry_operations ovl_dentry_operations = { 167 .d_release = ovl_dentry_release, 168 .d_real = ovl_d_real, 169 .d_revalidate = ovl_dentry_revalidate, 170 .d_weak_revalidate = ovl_dentry_weak_revalidate, 171 }; 172 173 static struct kmem_cache *ovl_inode_cachep; 174 175 static struct inode *ovl_alloc_inode(struct super_block *sb) 176 { 177 struct ovl_inode *oi = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL); 178 179 if (!oi) 180 return NULL; 181 182 oi->cache = NULL; 183 oi->redirect = NULL; 184 oi->version = 0; 185 oi->flags = 0; 186 oi->__upperdentry = NULL; 187 oi->lower = NULL; 188 oi->lowerdata = NULL; 189 mutex_init(&oi->lock); 190 191 return &oi->vfs_inode; 192 } 193 194 static void ovl_free_inode(struct inode *inode) 195 { 196 struct ovl_inode *oi = OVL_I(inode); 197 198 kfree(oi->redirect); 199 mutex_destroy(&oi->lock); 200 kmem_cache_free(ovl_inode_cachep, oi); 201 } 202 203 static void ovl_destroy_inode(struct inode *inode) 204 { 205 struct ovl_inode *oi = OVL_I(inode); 206 207 dput(oi->__upperdentry); 208 iput(oi->lower); 209 if (S_ISDIR(inode->i_mode)) 210 ovl_dir_cache_free(inode); 211 else 212 iput(oi->lowerdata); 213 } 214 215 static void ovl_free_fs(struct ovl_fs *ofs) 216 { 217 struct vfsmount **mounts; 218 unsigned i; 219 220 iput(ofs->workbasedir_trap); 221 iput(ofs->indexdir_trap); 222 iput(ofs->workdir_trap); 223 dput(ofs->whiteout); 224 dput(ofs->indexdir); 225 dput(ofs->workdir); 226 if (ofs->workdir_locked) 227 ovl_inuse_unlock(ofs->workbasedir); 228 dput(ofs->workbasedir); 229 if (ofs->upperdir_locked) 230 ovl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root); 231 232 /* Hack! Reuse ofs->layers as a vfsmount array before freeing it */ 233 mounts = (struct vfsmount **) ofs->layers; 234 for (i = 0; i < ofs->numlayer; i++) { 235 iput(ofs->layers[i].trap); 236 mounts[i] = ofs->layers[i].mnt; 237 } 238 kern_unmount_array(mounts, ofs->numlayer); 239 kfree(ofs->layers); 240 for (i = 0; i < ofs->numfs; i++) 241 free_anon_bdev(ofs->fs[i].pseudo_dev); 242 kfree(ofs->fs); 243 244 kfree(ofs->config.lowerdir); 245 kfree(ofs->config.upperdir); 246 kfree(ofs->config.workdir); 247 kfree(ofs->config.redirect_mode); 248 if (ofs->creator_cred) 249 put_cred(ofs->creator_cred); 250 kfree(ofs); 251 } 252 253 static void ovl_put_super(struct super_block *sb) 254 { 255 struct ovl_fs *ofs = sb->s_fs_info; 256 257 ovl_free_fs(ofs); 258 } 259 260 /* Sync real dirty inodes in upper filesystem (if it exists) */ 261 static int ovl_sync_fs(struct super_block *sb, int wait) 262 { 263 struct ovl_fs *ofs = sb->s_fs_info; 264 struct super_block *upper_sb; 265 int ret; 266 267 ret = ovl_sync_status(ofs); 268 /* 269 * We have to always set the err, because the return value isn't 270 * checked in syncfs, and instead indirectly return an error via 271 * the sb's writeback errseq, which VFS inspects after this call. 272 */ 273 if (ret < 0) { 274 errseq_set(&sb->s_wb_err, -EIO); 275 return -EIO; 276 } 277 278 if (!ret) 279 return ret; 280 281 /* 282 * Not called for sync(2) call or an emergency sync (SB_I_SKIP_SYNC). 283 * All the super blocks will be iterated, including upper_sb. 284 * 285 * If this is a syncfs(2) call, then we do need to call 286 * sync_filesystem() on upper_sb, but enough if we do it when being 287 * called with wait == 1. 288 */ 289 if (!wait) 290 return 0; 291 292 upper_sb = ovl_upper_mnt(ofs)->mnt_sb; 293 294 down_read(&upper_sb->s_umount); 295 ret = sync_filesystem(upper_sb); 296 up_read(&upper_sb->s_umount); 297 298 return ret; 299 } 300 301 /** 302 * ovl_statfs 303 * @sb: The overlayfs super block 304 * @buf: The struct kstatfs to fill in with stats 305 * 306 * Get the filesystem statistics. As writes always target the upper layer 307 * filesystem pass the statfs to the upper filesystem (if it exists) 308 */ 309 static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) 310 { 311 struct ovl_fs *ofs = dentry->d_sb->s_fs_info; 312 struct dentry *root_dentry = dentry->d_sb->s_root; 313 struct path path; 314 int err; 315 316 ovl_path_real(root_dentry, &path); 317 318 err = vfs_statfs(&path, buf); 319 if (!err) { 320 buf->f_namelen = ofs->namelen; 321 buf->f_type = OVERLAYFS_SUPER_MAGIC; 322 } 323 324 return err; 325 } 326 327 /* Will this overlay be forced to mount/remount ro? */ 328 static bool ovl_force_readonly(struct ovl_fs *ofs) 329 { 330 return (!ovl_upper_mnt(ofs) || !ofs->workdir); 331 } 332 333 static const char *ovl_redirect_mode_def(void) 334 { 335 return ovl_redirect_dir_def ? "on" : "off"; 336 } 337 338 static const char * const ovl_xino_str[] = { 339 "off", 340 "auto", 341 "on", 342 }; 343 344 static inline int ovl_xino_def(void) 345 { 346 return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF; 347 } 348 349 /** 350 * ovl_show_options 351 * 352 * Prints the mount options for a given superblock. 353 * Returns zero; does not fail. 354 */ 355 static int ovl_show_options(struct seq_file *m, struct dentry *dentry) 356 { 357 struct super_block *sb = dentry->d_sb; 358 struct ovl_fs *ofs = sb->s_fs_info; 359 360 seq_show_option(m, "lowerdir", ofs->config.lowerdir); 361 if (ofs->config.upperdir) { 362 seq_show_option(m, "upperdir", ofs->config.upperdir); 363 seq_show_option(m, "workdir", ofs->config.workdir); 364 } 365 if (ofs->config.default_permissions) 366 seq_puts(m, ",default_permissions"); 367 if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0) 368 seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode); 369 if (ofs->config.index != ovl_index_def) 370 seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off"); 371 if (!ofs->config.uuid) 372 seq_puts(m, ",uuid=off"); 373 if (ofs->config.nfs_export != ovl_nfs_export_def) 374 seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ? 375 "on" : "off"); 376 if (ofs->config.xino != ovl_xino_def() && !ovl_same_fs(sb)) 377 seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]); 378 if (ofs->config.metacopy != ovl_metacopy_def) 379 seq_printf(m, ",metacopy=%s", 380 ofs->config.metacopy ? "on" : "off"); 381 if (ofs->config.ovl_volatile) 382 seq_puts(m, ",volatile"); 383 if (ofs->config.userxattr) 384 seq_puts(m, ",userxattr"); 385 return 0; 386 } 387 388 static int ovl_remount(struct super_block *sb, int *flags, char *data) 389 { 390 struct ovl_fs *ofs = sb->s_fs_info; 391 struct super_block *upper_sb; 392 int ret = 0; 393 394 if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs)) 395 return -EROFS; 396 397 if (*flags & SB_RDONLY && !sb_rdonly(sb)) { 398 upper_sb = ovl_upper_mnt(ofs)->mnt_sb; 399 if (ovl_should_sync(ofs)) { 400 down_read(&upper_sb->s_umount); 401 ret = sync_filesystem(upper_sb); 402 up_read(&upper_sb->s_umount); 403 } 404 } 405 406 return ret; 407 } 408 409 static const struct super_operations ovl_super_operations = { 410 .alloc_inode = ovl_alloc_inode, 411 .free_inode = ovl_free_inode, 412 .destroy_inode = ovl_destroy_inode, 413 .drop_inode = generic_delete_inode, 414 .put_super = ovl_put_super, 415 .sync_fs = ovl_sync_fs, 416 .statfs = ovl_statfs, 417 .show_options = ovl_show_options, 418 .remount_fs = ovl_remount, 419 }; 420 421 enum { 422 OPT_LOWERDIR, 423 OPT_UPPERDIR, 424 OPT_WORKDIR, 425 OPT_DEFAULT_PERMISSIONS, 426 OPT_REDIRECT_DIR, 427 OPT_INDEX_ON, 428 OPT_INDEX_OFF, 429 OPT_UUID_ON, 430 OPT_UUID_OFF, 431 OPT_NFS_EXPORT_ON, 432 OPT_USERXATTR, 433 OPT_NFS_EXPORT_OFF, 434 OPT_XINO_ON, 435 OPT_XINO_OFF, 436 OPT_XINO_AUTO, 437 OPT_METACOPY_ON, 438 OPT_METACOPY_OFF, 439 OPT_VOLATILE, 440 OPT_ERR, 441 }; 442 443 static const match_table_t ovl_tokens = { 444 {OPT_LOWERDIR, "lowerdir=%s"}, 445 {OPT_UPPERDIR, "upperdir=%s"}, 446 {OPT_WORKDIR, "workdir=%s"}, 447 {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, 448 {OPT_REDIRECT_DIR, "redirect_dir=%s"}, 449 {OPT_INDEX_ON, "index=on"}, 450 {OPT_INDEX_OFF, "index=off"}, 451 {OPT_USERXATTR, "userxattr"}, 452 {OPT_UUID_ON, "uuid=on"}, 453 {OPT_UUID_OFF, "uuid=off"}, 454 {OPT_NFS_EXPORT_ON, "nfs_export=on"}, 455 {OPT_NFS_EXPORT_OFF, "nfs_export=off"}, 456 {OPT_XINO_ON, "xino=on"}, 457 {OPT_XINO_OFF, "xino=off"}, 458 {OPT_XINO_AUTO, "xino=auto"}, 459 {OPT_METACOPY_ON, "metacopy=on"}, 460 {OPT_METACOPY_OFF, "metacopy=off"}, 461 {OPT_VOLATILE, "volatile"}, 462 {OPT_ERR, NULL} 463 }; 464 465 static char *ovl_next_opt(char **s) 466 { 467 char *sbegin = *s; 468 char *p; 469 470 if (sbegin == NULL) 471 return NULL; 472 473 for (p = sbegin; *p; p++) { 474 if (*p == '\\') { 475 p++; 476 if (!*p) 477 break; 478 } else if (*p == ',') { 479 *p = '\0'; 480 *s = p + 1; 481 return sbegin; 482 } 483 } 484 *s = NULL; 485 return sbegin; 486 } 487 488 static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) 489 { 490 if (strcmp(mode, "on") == 0) { 491 config->redirect_dir = true; 492 /* 493 * Does not make sense to have redirect creation without 494 * redirect following. 495 */ 496 config->redirect_follow = true; 497 } else if (strcmp(mode, "follow") == 0) { 498 config->redirect_follow = true; 499 } else if (strcmp(mode, "off") == 0) { 500 if (ovl_redirect_always_follow) 501 config->redirect_follow = true; 502 } else if (strcmp(mode, "nofollow") != 0) { 503 pr_err("bad mount option \"redirect_dir=%s\"\n", 504 mode); 505 return -EINVAL; 506 } 507 508 return 0; 509 } 510 511 static int ovl_parse_opt(char *opt, struct ovl_config *config) 512 { 513 char *p; 514 int err; 515 bool metacopy_opt = false, redirect_opt = false; 516 bool nfs_export_opt = false, index_opt = false; 517 518 config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); 519 if (!config->redirect_mode) 520 return -ENOMEM; 521 522 while ((p = ovl_next_opt(&opt)) != NULL) { 523 int token; 524 substring_t args[MAX_OPT_ARGS]; 525 526 if (!*p) 527 continue; 528 529 token = match_token(p, ovl_tokens, args); 530 switch (token) { 531 case OPT_UPPERDIR: 532 kfree(config->upperdir); 533 config->upperdir = match_strdup(&args[0]); 534 if (!config->upperdir) 535 return -ENOMEM; 536 break; 537 538 case OPT_LOWERDIR: 539 kfree(config->lowerdir); 540 config->lowerdir = match_strdup(&args[0]); 541 if (!config->lowerdir) 542 return -ENOMEM; 543 break; 544 545 case OPT_WORKDIR: 546 kfree(config->workdir); 547 config->workdir = match_strdup(&args[0]); 548 if (!config->workdir) 549 return -ENOMEM; 550 break; 551 552 case OPT_DEFAULT_PERMISSIONS: 553 config->default_permissions = true; 554 break; 555 556 case OPT_REDIRECT_DIR: 557 kfree(config->redirect_mode); 558 config->redirect_mode = match_strdup(&args[0]); 559 if (!config->redirect_mode) 560 return -ENOMEM; 561 redirect_opt = true; 562 break; 563 564 case OPT_INDEX_ON: 565 config->index = true; 566 index_opt = true; 567 break; 568 569 case OPT_INDEX_OFF: 570 config->index = false; 571 index_opt = true; 572 break; 573 574 case OPT_UUID_ON: 575 config->uuid = true; 576 break; 577 578 case OPT_UUID_OFF: 579 config->uuid = false; 580 break; 581 582 case OPT_NFS_EXPORT_ON: 583 config->nfs_export = true; 584 nfs_export_opt = true; 585 break; 586 587 case OPT_NFS_EXPORT_OFF: 588 config->nfs_export = false; 589 nfs_export_opt = true; 590 break; 591 592 case OPT_XINO_ON: 593 config->xino = OVL_XINO_ON; 594 break; 595 596 case OPT_XINO_OFF: 597 config->xino = OVL_XINO_OFF; 598 break; 599 600 case OPT_XINO_AUTO: 601 config->xino = OVL_XINO_AUTO; 602 break; 603 604 case OPT_METACOPY_ON: 605 config->metacopy = true; 606 metacopy_opt = true; 607 break; 608 609 case OPT_METACOPY_OFF: 610 config->metacopy = false; 611 metacopy_opt = true; 612 break; 613 614 case OPT_VOLATILE: 615 config->ovl_volatile = true; 616 break; 617 618 case OPT_USERXATTR: 619 config->userxattr = true; 620 break; 621 622 default: 623 pr_err("unrecognized mount option \"%s\" or missing value\n", 624 p); 625 return -EINVAL; 626 } 627 } 628 629 /* Workdir/index are useless in non-upper mount */ 630 if (!config->upperdir) { 631 if (config->workdir) { 632 pr_info("option \"workdir=%s\" is useless in a non-upper mount, ignore\n", 633 config->workdir); 634 kfree(config->workdir); 635 config->workdir = NULL; 636 } 637 if (config->index && index_opt) { 638 pr_info("option \"index=on\" is useless in a non-upper mount, ignore\n"); 639 index_opt = false; 640 } 641 config->index = false; 642 } 643 644 if (!config->upperdir && config->ovl_volatile) { 645 pr_info("option \"volatile\" is meaningless in a non-upper mount, ignoring it.\n"); 646 config->ovl_volatile = false; 647 } 648 649 err = ovl_parse_redirect_mode(config, config->redirect_mode); 650 if (err) 651 return err; 652 653 /* 654 * This is to make the logic below simpler. It doesn't make any other 655 * difference, since config->redirect_dir is only used for upper. 656 */ 657 if (!config->upperdir && config->redirect_follow) 658 config->redirect_dir = true; 659 660 /* Resolve metacopy -> redirect_dir dependency */ 661 if (config->metacopy && !config->redirect_dir) { 662 if (metacopy_opt && redirect_opt) { 663 pr_err("conflicting options: metacopy=on,redirect_dir=%s\n", 664 config->redirect_mode); 665 return -EINVAL; 666 } 667 if (redirect_opt) { 668 /* 669 * There was an explicit redirect_dir=... that resulted 670 * in this conflict. 671 */ 672 pr_info("disabling metacopy due to redirect_dir=%s\n", 673 config->redirect_mode); 674 config->metacopy = false; 675 } else { 676 /* Automatically enable redirect otherwise. */ 677 config->redirect_follow = config->redirect_dir = true; 678 } 679 } 680 681 /* Resolve nfs_export -> index dependency */ 682 if (config->nfs_export && !config->index) { 683 if (!config->upperdir && config->redirect_follow) { 684 pr_info("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n"); 685 config->nfs_export = false; 686 } else if (nfs_export_opt && index_opt) { 687 pr_err("conflicting options: nfs_export=on,index=off\n"); 688 return -EINVAL; 689 } else if (index_opt) { 690 /* 691 * There was an explicit index=off that resulted 692 * in this conflict. 693 */ 694 pr_info("disabling nfs_export due to index=off\n"); 695 config->nfs_export = false; 696 } else { 697 /* Automatically enable index otherwise. */ 698 config->index = true; 699 } 700 } 701 702 /* Resolve nfs_export -> !metacopy dependency */ 703 if (config->nfs_export && config->metacopy) { 704 if (nfs_export_opt && metacopy_opt) { 705 pr_err("conflicting options: nfs_export=on,metacopy=on\n"); 706 return -EINVAL; 707 } 708 if (metacopy_opt) { 709 /* 710 * There was an explicit metacopy=on that resulted 711 * in this conflict. 712 */ 713 pr_info("disabling nfs_export due to metacopy=on\n"); 714 config->nfs_export = false; 715 } else { 716 /* 717 * There was an explicit nfs_export=on that resulted 718 * in this conflict. 719 */ 720 pr_info("disabling metacopy due to nfs_export=on\n"); 721 config->metacopy = false; 722 } 723 } 724 725 726 /* Resolve userxattr -> !redirect && !metacopy dependency */ 727 if (config->userxattr) { 728 if (config->redirect_follow && redirect_opt) { 729 pr_err("conflicting options: userxattr,redirect_dir=%s\n", 730 config->redirect_mode); 731 return -EINVAL; 732 } 733 if (config->metacopy && metacopy_opt) { 734 pr_err("conflicting options: userxattr,metacopy=on\n"); 735 return -EINVAL; 736 } 737 /* 738 * Silently disable default setting of redirect and metacopy. 739 * This shall be the default in the future as well: these 740 * options must be explicitly enabled if used together with 741 * userxattr. 742 */ 743 config->redirect_dir = config->redirect_follow = false; 744 config->metacopy = false; 745 } 746 747 return 0; 748 } 749 750 #define OVL_WORKDIR_NAME "work" 751 #define OVL_INDEXDIR_NAME "index" 752 753 static struct dentry *ovl_workdir_create(struct ovl_fs *ofs, 754 const char *name, bool persist) 755 { 756 struct inode *dir = ofs->workbasedir->d_inode; 757 struct vfsmount *mnt = ovl_upper_mnt(ofs); 758 struct dentry *work; 759 int err; 760 bool retried = false; 761 762 inode_lock_nested(dir, I_MUTEX_PARENT); 763 retry: 764 work = lookup_one_len(name, ofs->workbasedir, strlen(name)); 765 766 if (!IS_ERR(work)) { 767 struct iattr attr = { 768 .ia_valid = ATTR_MODE, 769 .ia_mode = S_IFDIR | 0, 770 }; 771 772 if (work->d_inode) { 773 err = -EEXIST; 774 if (retried) 775 goto out_dput; 776 777 if (persist) 778 goto out_unlock; 779 780 retried = true; 781 err = ovl_workdir_cleanup(dir, mnt, work, 0); 782 dput(work); 783 if (err == -EINVAL) { 784 work = ERR_PTR(err); 785 goto out_unlock; 786 } 787 goto retry; 788 } 789 790 work = ovl_create_real(dir, work, OVL_CATTR(attr.ia_mode)); 791 err = PTR_ERR(work); 792 if (IS_ERR(work)) 793 goto out_err; 794 795 /* 796 * Try to remove POSIX ACL xattrs from workdir. We are good if: 797 * 798 * a) success (there was a POSIX ACL xattr and was removed) 799 * b) -ENODATA (there was no POSIX ACL xattr) 800 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported) 801 * 802 * There are various other error values that could effectively 803 * mean that the xattr doesn't exist (e.g. -ERANGE is returned 804 * if the xattr name is too long), but the set of filesystems 805 * allowed as upper are limited to "normal" ones, where checking 806 * for the above two errors is sufficient. 807 */ 808 err = vfs_removexattr(&init_user_ns, work, 809 XATTR_NAME_POSIX_ACL_DEFAULT); 810 if (err && err != -ENODATA && err != -EOPNOTSUPP) 811 goto out_dput; 812 813 err = vfs_removexattr(&init_user_ns, work, 814 XATTR_NAME_POSIX_ACL_ACCESS); 815 if (err && err != -ENODATA && err != -EOPNOTSUPP) 816 goto out_dput; 817 818 /* Clear any inherited mode bits */ 819 inode_lock(work->d_inode); 820 err = notify_change(&init_user_ns, work, &attr, NULL); 821 inode_unlock(work->d_inode); 822 if (err) 823 goto out_dput; 824 } else { 825 err = PTR_ERR(work); 826 goto out_err; 827 } 828 out_unlock: 829 inode_unlock(dir); 830 return work; 831 832 out_dput: 833 dput(work); 834 out_err: 835 pr_warn("failed to create directory %s/%s (errno: %i); mounting read-only\n", 836 ofs->config.workdir, name, -err); 837 work = NULL; 838 goto out_unlock; 839 } 840 841 static void ovl_unescape(char *s) 842 { 843 char *d = s; 844 845 for (;; s++, d++) { 846 if (*s == '\\') 847 s++; 848 *d = *s; 849 if (!*s) 850 break; 851 } 852 } 853 854 static int ovl_mount_dir_noesc(const char *name, struct path *path) 855 { 856 int err = -EINVAL; 857 858 if (!*name) { 859 pr_err("empty lowerdir\n"); 860 goto out; 861 } 862 err = kern_path(name, LOOKUP_FOLLOW, path); 863 if (err) { 864 pr_err("failed to resolve '%s': %i\n", name, err); 865 goto out; 866 } 867 err = -EINVAL; 868 if (ovl_dentry_weird(path->dentry)) { 869 pr_err("filesystem on '%s' not supported\n", name); 870 goto out_put; 871 } 872 if (mnt_user_ns(path->mnt) != &init_user_ns) { 873 pr_err("idmapped layers are currently not supported\n"); 874 goto out_put; 875 } 876 if (!d_is_dir(path->dentry)) { 877 pr_err("'%s' not a directory\n", name); 878 goto out_put; 879 } 880 return 0; 881 882 out_put: 883 path_put_init(path); 884 out: 885 return err; 886 } 887 888 static int ovl_mount_dir(const char *name, struct path *path) 889 { 890 int err = -ENOMEM; 891 char *tmp = kstrdup(name, GFP_KERNEL); 892 893 if (tmp) { 894 ovl_unescape(tmp); 895 err = ovl_mount_dir_noesc(tmp, path); 896 897 if (!err && path->dentry->d_flags & DCACHE_OP_REAL) { 898 pr_err("filesystem on '%s' not supported as upperdir\n", 899 tmp); 900 path_put_init(path); 901 err = -EINVAL; 902 } 903 kfree(tmp); 904 } 905 return err; 906 } 907 908 static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs, 909 const char *name) 910 { 911 struct kstatfs statfs; 912 int err = vfs_statfs(path, &statfs); 913 914 if (err) 915 pr_err("statfs failed on '%s'\n", name); 916 else 917 ofs->namelen = max(ofs->namelen, statfs.f_namelen); 918 919 return err; 920 } 921 922 static int ovl_lower_dir(const char *name, struct path *path, 923 struct ovl_fs *ofs, int *stack_depth) 924 { 925 int fh_type; 926 int err; 927 928 err = ovl_mount_dir_noesc(name, path); 929 if (err) 930 return err; 931 932 err = ovl_check_namelen(path, ofs, name); 933 if (err) 934 return err; 935 936 *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); 937 938 /* 939 * The inodes index feature and NFS export need to encode and decode 940 * file handles, so they require that all layers support them. 941 */ 942 fh_type = ovl_can_decode_fh(path->dentry->d_sb); 943 if ((ofs->config.nfs_export || 944 (ofs->config.index && ofs->config.upperdir)) && !fh_type) { 945 ofs->config.index = false; 946 ofs->config.nfs_export = false; 947 pr_warn("fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n", 948 name); 949 } 950 /* 951 * Decoding origin file handle is required for persistent st_ino. 952 * Without persistent st_ino, xino=auto falls back to xino=off. 953 */ 954 if (ofs->config.xino == OVL_XINO_AUTO && 955 ofs->config.upperdir && !fh_type) { 956 ofs->config.xino = OVL_XINO_OFF; 957 pr_warn("fs on '%s' does not support file handles, falling back to xino=off.\n", 958 name); 959 } 960 961 /* Check if lower fs has 32bit inode numbers */ 962 if (fh_type != FILEID_INO32_GEN) 963 ofs->xino_mode = -1; 964 965 return 0; 966 } 967 968 /* Workdir should not be subdir of upperdir and vice versa */ 969 static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) 970 { 971 bool ok = false; 972 973 if (workdir != upperdir) { 974 ok = (lock_rename(workdir, upperdir) == NULL); 975 unlock_rename(workdir, upperdir); 976 } 977 return ok; 978 } 979 980 static unsigned int ovl_split_lowerdirs(char *str) 981 { 982 unsigned int ctr = 1; 983 char *s, *d; 984 985 for (s = d = str;; s++, d++) { 986 if (*s == '\\') { 987 s++; 988 } else if (*s == ':') { 989 *d = '\0'; 990 ctr++; 991 continue; 992 } 993 *d = *s; 994 if (!*s) 995 break; 996 } 997 return ctr; 998 } 999 1000 static int __maybe_unused 1001 ovl_posix_acl_xattr_get(const struct xattr_handler *handler, 1002 struct dentry *dentry, struct inode *inode, 1003 const char *name, void *buffer, size_t size) 1004 { 1005 return ovl_xattr_get(dentry, inode, handler->name, buffer, size); 1006 } 1007 1008 static int __maybe_unused 1009 ovl_posix_acl_xattr_set(const struct xattr_handler *handler, 1010 struct user_namespace *mnt_userns, 1011 struct dentry *dentry, struct inode *inode, 1012 const char *name, const void *value, 1013 size_t size, int flags) 1014 { 1015 struct dentry *workdir = ovl_workdir(dentry); 1016 struct inode *realinode = ovl_inode_real(inode); 1017 struct posix_acl *acl = NULL; 1018 int err; 1019 1020 /* Check that everything is OK before copy-up */ 1021 if (value) { 1022 acl = posix_acl_from_xattr(&init_user_ns, value, size); 1023 if (IS_ERR(acl)) 1024 return PTR_ERR(acl); 1025 } 1026 err = -EOPNOTSUPP; 1027 if (!IS_POSIXACL(d_inode(workdir))) 1028 goto out_acl_release; 1029 if (!realinode->i_op->set_acl) 1030 goto out_acl_release; 1031 if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) { 1032 err = acl ? -EACCES : 0; 1033 goto out_acl_release; 1034 } 1035 err = -EPERM; 1036 if (!inode_owner_or_capable(&init_user_ns, inode)) 1037 goto out_acl_release; 1038 1039 posix_acl_release(acl); 1040 1041 /* 1042 * Check if sgid bit needs to be cleared (actual setacl operation will 1043 * be done with mounter's capabilities and so that won't do it for us). 1044 */ 1045 if (unlikely(inode->i_mode & S_ISGID) && 1046 handler->flags == ACL_TYPE_ACCESS && 1047 !in_group_p(inode->i_gid) && 1048 !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID)) { 1049 struct iattr iattr = { .ia_valid = ATTR_KILL_SGID }; 1050 1051 err = ovl_setattr(&init_user_ns, dentry, &iattr); 1052 if (err) 1053 return err; 1054 } 1055 1056 err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags); 1057 return err; 1058 1059 out_acl_release: 1060 posix_acl_release(acl); 1061 return err; 1062 } 1063 1064 static int ovl_own_xattr_get(const struct xattr_handler *handler, 1065 struct dentry *dentry, struct inode *inode, 1066 const char *name, void *buffer, size_t size) 1067 { 1068 return -EOPNOTSUPP; 1069 } 1070 1071 static int ovl_own_xattr_set(const struct xattr_handler *handler, 1072 struct user_namespace *mnt_userns, 1073 struct dentry *dentry, struct inode *inode, 1074 const char *name, const void *value, 1075 size_t size, int flags) 1076 { 1077 return -EOPNOTSUPP; 1078 } 1079 1080 static int ovl_other_xattr_get(const struct xattr_handler *handler, 1081 struct dentry *dentry, struct inode *inode, 1082 const char *name, void *buffer, size_t size) 1083 { 1084 return ovl_xattr_get(dentry, inode, name, buffer, size); 1085 } 1086 1087 static int ovl_other_xattr_set(const struct xattr_handler *handler, 1088 struct user_namespace *mnt_userns, 1089 struct dentry *dentry, struct inode *inode, 1090 const char *name, const void *value, 1091 size_t size, int flags) 1092 { 1093 return ovl_xattr_set(dentry, inode, name, value, size, flags); 1094 } 1095 1096 static const struct xattr_handler __maybe_unused 1097 ovl_posix_acl_access_xattr_handler = { 1098 .name = XATTR_NAME_POSIX_ACL_ACCESS, 1099 .flags = ACL_TYPE_ACCESS, 1100 .get = ovl_posix_acl_xattr_get, 1101 .set = ovl_posix_acl_xattr_set, 1102 }; 1103 1104 static const struct xattr_handler __maybe_unused 1105 ovl_posix_acl_default_xattr_handler = { 1106 .name = XATTR_NAME_POSIX_ACL_DEFAULT, 1107 .flags = ACL_TYPE_DEFAULT, 1108 .get = ovl_posix_acl_xattr_get, 1109 .set = ovl_posix_acl_xattr_set, 1110 }; 1111 1112 static const struct xattr_handler ovl_own_trusted_xattr_handler = { 1113 .prefix = OVL_XATTR_TRUSTED_PREFIX, 1114 .get = ovl_own_xattr_get, 1115 .set = ovl_own_xattr_set, 1116 }; 1117 1118 static const struct xattr_handler ovl_own_user_xattr_handler = { 1119 .prefix = OVL_XATTR_USER_PREFIX, 1120 .get = ovl_own_xattr_get, 1121 .set = ovl_own_xattr_set, 1122 }; 1123 1124 static const struct xattr_handler ovl_other_xattr_handler = { 1125 .prefix = "", /* catch all */ 1126 .get = ovl_other_xattr_get, 1127 .set = ovl_other_xattr_set, 1128 }; 1129 1130 static const struct xattr_handler *ovl_trusted_xattr_handlers[] = { 1131 #ifdef CONFIG_FS_POSIX_ACL 1132 &ovl_posix_acl_access_xattr_handler, 1133 &ovl_posix_acl_default_xattr_handler, 1134 #endif 1135 &ovl_own_trusted_xattr_handler, 1136 &ovl_other_xattr_handler, 1137 NULL 1138 }; 1139 1140 static const struct xattr_handler *ovl_user_xattr_handlers[] = { 1141 #ifdef CONFIG_FS_POSIX_ACL 1142 &ovl_posix_acl_access_xattr_handler, 1143 &ovl_posix_acl_default_xattr_handler, 1144 #endif 1145 &ovl_own_user_xattr_handler, 1146 &ovl_other_xattr_handler, 1147 NULL 1148 }; 1149 1150 static int ovl_setup_trap(struct super_block *sb, struct dentry *dir, 1151 struct inode **ptrap, const char *name) 1152 { 1153 struct inode *trap; 1154 int err; 1155 1156 trap = ovl_get_trap_inode(sb, dir); 1157 err = PTR_ERR_OR_ZERO(trap); 1158 if (err) { 1159 if (err == -ELOOP) 1160 pr_err("conflicting %s path\n", name); 1161 return err; 1162 } 1163 1164 *ptrap = trap; 1165 return 0; 1166 } 1167 1168 /* 1169 * Determine how we treat concurrent use of upperdir/workdir based on the 1170 * index feature. This is papering over mount leaks of container runtimes, 1171 * for example, an old overlay mount is leaked and now its upperdir is 1172 * attempted to be used as a lower layer in a new overlay mount. 1173 */ 1174 static int ovl_report_in_use(struct ovl_fs *ofs, const char *name) 1175 { 1176 if (ofs->config.index) { 1177 pr_err("%s is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.\n", 1178 name); 1179 return -EBUSY; 1180 } else { 1181 pr_warn("%s is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.\n", 1182 name); 1183 return 0; 1184 } 1185 } 1186 1187 static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, 1188 struct ovl_layer *upper_layer, struct path *upperpath) 1189 { 1190 struct vfsmount *upper_mnt; 1191 int err; 1192 1193 err = ovl_mount_dir(ofs->config.upperdir, upperpath); 1194 if (err) 1195 goto out; 1196 1197 /* Upperdir path should not be r/o */ 1198 if (__mnt_is_readonly(upperpath->mnt)) { 1199 pr_err("upper fs is r/o, try multi-lower layers mount\n"); 1200 err = -EINVAL; 1201 goto out; 1202 } 1203 1204 err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir); 1205 if (err) 1206 goto out; 1207 1208 err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap, 1209 "upperdir"); 1210 if (err) 1211 goto out; 1212 1213 upper_mnt = clone_private_mount(upperpath); 1214 err = PTR_ERR(upper_mnt); 1215 if (IS_ERR(upper_mnt)) { 1216 pr_err("failed to clone upperpath\n"); 1217 goto out; 1218 } 1219 1220 /* Don't inherit atime flags */ 1221 upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); 1222 upper_layer->mnt = upper_mnt; 1223 upper_layer->idx = 0; 1224 upper_layer->fsid = 0; 1225 1226 /* 1227 * Inherit SB_NOSEC flag from upperdir. 1228 * 1229 * This optimization changes behavior when a security related attribute 1230 * (suid/sgid/security.*) is changed on an underlying layer. This is 1231 * okay because we don't yet have guarantees in that case, but it will 1232 * need careful treatment once we want to honour changes to underlying 1233 * filesystems. 1234 */ 1235 if (upper_mnt->mnt_sb->s_flags & SB_NOSEC) 1236 sb->s_flags |= SB_NOSEC; 1237 1238 if (ovl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root)) { 1239 ofs->upperdir_locked = true; 1240 } else { 1241 err = ovl_report_in_use(ofs, "upperdir"); 1242 if (err) 1243 goto out; 1244 } 1245 1246 err = 0; 1247 out: 1248 return err; 1249 } 1250 1251 /* 1252 * Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and 1253 * negative values if error is encountered. 1254 */ 1255 static int ovl_check_rename_whiteout(struct dentry *workdir) 1256 { 1257 struct inode *dir = d_inode(workdir); 1258 struct dentry *temp; 1259 struct dentry *dest; 1260 struct dentry *whiteout; 1261 struct name_snapshot name; 1262 int err; 1263 1264 inode_lock_nested(dir, I_MUTEX_PARENT); 1265 1266 temp = ovl_create_temp(workdir, OVL_CATTR(S_IFREG | 0)); 1267 err = PTR_ERR(temp); 1268 if (IS_ERR(temp)) 1269 goto out_unlock; 1270 1271 dest = ovl_lookup_temp(workdir); 1272 err = PTR_ERR(dest); 1273 if (IS_ERR(dest)) { 1274 dput(temp); 1275 goto out_unlock; 1276 } 1277 1278 /* Name is inline and stable - using snapshot as a copy helper */ 1279 take_dentry_name_snapshot(&name, temp); 1280 err = ovl_do_rename(dir, temp, dir, dest, RENAME_WHITEOUT); 1281 if (err) { 1282 if (err == -EINVAL) 1283 err = 0; 1284 goto cleanup_temp; 1285 } 1286 1287 whiteout = lookup_one_len(name.name.name, workdir, name.name.len); 1288 err = PTR_ERR(whiteout); 1289 if (IS_ERR(whiteout)) 1290 goto cleanup_temp; 1291 1292 err = ovl_is_whiteout(whiteout); 1293 1294 /* Best effort cleanup of whiteout and temp file */ 1295 if (err) 1296 ovl_cleanup(dir, whiteout); 1297 dput(whiteout); 1298 1299 cleanup_temp: 1300 ovl_cleanup(dir, temp); 1301 release_dentry_name_snapshot(&name); 1302 dput(temp); 1303 dput(dest); 1304 1305 out_unlock: 1306 inode_unlock(dir); 1307 1308 return err; 1309 } 1310 1311 static struct dentry *ovl_lookup_or_create(struct dentry *parent, 1312 const char *name, umode_t mode) 1313 { 1314 size_t len = strlen(name); 1315 struct dentry *child; 1316 1317 inode_lock_nested(parent->d_inode, I_MUTEX_PARENT); 1318 child = lookup_one_len(name, parent, len); 1319 if (!IS_ERR(child) && !child->d_inode) 1320 child = ovl_create_real(parent->d_inode, child, 1321 OVL_CATTR(mode)); 1322 inode_unlock(parent->d_inode); 1323 dput(parent); 1324 1325 return child; 1326 } 1327 1328 /* 1329 * Creates $workdir/work/incompat/volatile/dirty file if it is not already 1330 * present. 1331 */ 1332 static int ovl_create_volatile_dirty(struct ovl_fs *ofs) 1333 { 1334 unsigned int ctr; 1335 struct dentry *d = dget(ofs->workbasedir); 1336 static const char *const volatile_path[] = { 1337 OVL_WORKDIR_NAME, "incompat", "volatile", "dirty" 1338 }; 1339 const char *const *name = volatile_path; 1340 1341 for (ctr = ARRAY_SIZE(volatile_path); ctr; ctr--, name++) { 1342 d = ovl_lookup_or_create(d, *name, ctr > 1 ? S_IFDIR : S_IFREG); 1343 if (IS_ERR(d)) 1344 return PTR_ERR(d); 1345 } 1346 dput(d); 1347 return 0; 1348 } 1349 1350 static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs, 1351 struct path *workpath) 1352 { 1353 struct vfsmount *mnt = ovl_upper_mnt(ofs); 1354 struct dentry *temp, *workdir; 1355 bool rename_whiteout; 1356 bool d_type; 1357 int fh_type; 1358 int err; 1359 1360 err = mnt_want_write(mnt); 1361 if (err) 1362 return err; 1363 1364 workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false); 1365 err = PTR_ERR(workdir); 1366 if (IS_ERR_OR_NULL(workdir)) 1367 goto out; 1368 1369 ofs->workdir = workdir; 1370 1371 err = ovl_setup_trap(sb, ofs->workdir, &ofs->workdir_trap, "workdir"); 1372 if (err) 1373 goto out; 1374 1375 /* 1376 * Upper should support d_type, else whiteouts are visible. Given 1377 * workdir and upper are on same fs, we can do iterate_dir() on 1378 * workdir. This check requires successful creation of workdir in 1379 * previous step. 1380 */ 1381 err = ovl_check_d_type_supported(workpath); 1382 if (err < 0) 1383 goto out; 1384 1385 d_type = err; 1386 if (!d_type) 1387 pr_warn("upper fs needs to support d_type.\n"); 1388 1389 /* Check if upper/work fs supports O_TMPFILE */ 1390 temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0); 1391 ofs->tmpfile = !IS_ERR(temp); 1392 if (ofs->tmpfile) 1393 dput(temp); 1394 else 1395 pr_warn("upper fs does not support tmpfile.\n"); 1396 1397 1398 /* Check if upper/work fs supports RENAME_WHITEOUT */ 1399 err = ovl_check_rename_whiteout(ofs->workdir); 1400 if (err < 0) 1401 goto out; 1402 1403 rename_whiteout = err; 1404 if (!rename_whiteout) 1405 pr_warn("upper fs does not support RENAME_WHITEOUT.\n"); 1406 1407 /* 1408 * Check if upper/work fs supports (trusted|user).overlay.* xattr 1409 */ 1410 err = ovl_do_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1); 1411 if (err) { 1412 ofs->noxattr = true; 1413 if (ofs->config.index || ofs->config.metacopy) { 1414 ofs->config.index = false; 1415 ofs->config.metacopy = false; 1416 pr_warn("upper fs does not support xattr, falling back to index=off,metacopy=off.\n"); 1417 } 1418 /* 1419 * xattr support is required for persistent st_ino. 1420 * Without persistent st_ino, xino=auto falls back to xino=off. 1421 */ 1422 if (ofs->config.xino == OVL_XINO_AUTO) { 1423 ofs->config.xino = OVL_XINO_OFF; 1424 pr_warn("upper fs does not support xattr, falling back to xino=off.\n"); 1425 } 1426 err = 0; 1427 } else { 1428 ovl_do_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE); 1429 } 1430 1431 /* 1432 * We allowed sub-optimal upper fs configuration and don't want to break 1433 * users over kernel upgrade, but we never allowed remote upper fs, so 1434 * we can enforce strict requirements for remote upper fs. 1435 */ 1436 if (ovl_dentry_remote(ofs->workdir) && 1437 (!d_type || !rename_whiteout || ofs->noxattr)) { 1438 pr_err("upper fs missing required features.\n"); 1439 err = -EINVAL; 1440 goto out; 1441 } 1442 1443 /* 1444 * For volatile mount, create a incompat/volatile/dirty file to keep 1445 * track of it. 1446 */ 1447 if (ofs->config.ovl_volatile) { 1448 err = ovl_create_volatile_dirty(ofs); 1449 if (err < 0) { 1450 pr_err("Failed to create volatile/dirty file.\n"); 1451 goto out; 1452 } 1453 } 1454 1455 /* Check if upper/work fs supports file handles */ 1456 fh_type = ovl_can_decode_fh(ofs->workdir->d_sb); 1457 if (ofs->config.index && !fh_type) { 1458 ofs->config.index = false; 1459 pr_warn("upper fs does not support file handles, falling back to index=off.\n"); 1460 } 1461 1462 /* Check if upper fs has 32bit inode numbers */ 1463 if (fh_type != FILEID_INO32_GEN) 1464 ofs->xino_mode = -1; 1465 1466 /* NFS export of r/w mount depends on index */ 1467 if (ofs->config.nfs_export && !ofs->config.index) { 1468 pr_warn("NFS export requires \"index=on\", falling back to nfs_export=off.\n"); 1469 ofs->config.nfs_export = false; 1470 } 1471 out: 1472 mnt_drop_write(mnt); 1473 return err; 1474 } 1475 1476 static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs, 1477 struct path *upperpath) 1478 { 1479 int err; 1480 struct path workpath = { }; 1481 1482 err = ovl_mount_dir(ofs->config.workdir, &workpath); 1483 if (err) 1484 goto out; 1485 1486 err = -EINVAL; 1487 if (upperpath->mnt != workpath.mnt) { 1488 pr_err("workdir and upperdir must reside under the same mount\n"); 1489 goto out; 1490 } 1491 if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) { 1492 pr_err("workdir and upperdir must be separate subtrees\n"); 1493 goto out; 1494 } 1495 1496 ofs->workbasedir = dget(workpath.dentry); 1497 1498 if (ovl_inuse_trylock(ofs->workbasedir)) { 1499 ofs->workdir_locked = true; 1500 } else { 1501 err = ovl_report_in_use(ofs, "workdir"); 1502 if (err) 1503 goto out; 1504 } 1505 1506 err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap, 1507 "workdir"); 1508 if (err) 1509 goto out; 1510 1511 err = ovl_make_workdir(sb, ofs, &workpath); 1512 1513 out: 1514 path_put(&workpath); 1515 1516 return err; 1517 } 1518 1519 static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs, 1520 struct ovl_entry *oe, struct path *upperpath) 1521 { 1522 struct vfsmount *mnt = ovl_upper_mnt(ofs); 1523 struct dentry *indexdir; 1524 int err; 1525 1526 err = mnt_want_write(mnt); 1527 if (err) 1528 return err; 1529 1530 /* Verify lower root is upper root origin */ 1531 err = ovl_verify_origin(ofs, upperpath->dentry, 1532 oe->lowerstack[0].dentry, true); 1533 if (err) { 1534 pr_err("failed to verify upper root origin\n"); 1535 goto out; 1536 } 1537 1538 /* index dir will act also as workdir */ 1539 iput(ofs->workdir_trap); 1540 ofs->workdir_trap = NULL; 1541 dput(ofs->workdir); 1542 ofs->workdir = NULL; 1543 indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true); 1544 if (IS_ERR(indexdir)) { 1545 err = PTR_ERR(indexdir); 1546 } else if (indexdir) { 1547 ofs->indexdir = indexdir; 1548 ofs->workdir = dget(indexdir); 1549 1550 err = ovl_setup_trap(sb, ofs->indexdir, &ofs->indexdir_trap, 1551 "indexdir"); 1552 if (err) 1553 goto out; 1554 1555 /* 1556 * Verify upper root is exclusively associated with index dir. 1557 * Older kernels stored upper fh in ".overlay.origin" 1558 * xattr. If that xattr exists, verify that it is a match to 1559 * upper dir file handle. In any case, verify or set xattr 1560 * ".overlay.upper" to indicate that index may have 1561 * directory entries. 1562 */ 1563 if (ovl_check_origin_xattr(ofs, ofs->indexdir)) { 1564 err = ovl_verify_set_fh(ofs, ofs->indexdir, 1565 OVL_XATTR_ORIGIN, 1566 upperpath->dentry, true, false); 1567 if (err) 1568 pr_err("failed to verify index dir 'origin' xattr\n"); 1569 } 1570 err = ovl_verify_upper(ofs, ofs->indexdir, upperpath->dentry, 1571 true); 1572 if (err) 1573 pr_err("failed to verify index dir 'upper' xattr\n"); 1574 1575 /* Cleanup bad/stale/orphan index entries */ 1576 if (!err) 1577 err = ovl_indexdir_cleanup(ofs); 1578 } 1579 if (err || !ofs->indexdir) 1580 pr_warn("try deleting index dir or mounting with '-o index=off' to disable inodes index.\n"); 1581 1582 out: 1583 mnt_drop_write(mnt); 1584 return err; 1585 } 1586 1587 static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid) 1588 { 1589 unsigned int i; 1590 1591 if (!ofs->config.nfs_export && !ovl_upper_mnt(ofs)) 1592 return true; 1593 1594 /* 1595 * We allow using single lower with null uuid for index and nfs_export 1596 * for example to support those features with single lower squashfs. 1597 * To avoid regressions in setups of overlay with re-formatted lower 1598 * squashfs, do not allow decoding origin with lower null uuid unless 1599 * user opted-in to one of the new features that require following the 1600 * lower inode of non-dir upper. 1601 */ 1602 if (ovl_allow_offline_changes(ofs) && uuid_is_null(uuid)) 1603 return false; 1604 1605 for (i = 0; i < ofs->numfs; i++) { 1606 /* 1607 * We use uuid to associate an overlay lower file handle with a 1608 * lower layer, so we can accept lower fs with null uuid as long 1609 * as all lower layers with null uuid are on the same fs. 1610 * if we detect multiple lower fs with the same uuid, we 1611 * disable lower file handle decoding on all of them. 1612 */ 1613 if (ofs->fs[i].is_lower && 1614 uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) { 1615 ofs->fs[i].bad_uuid = true; 1616 return false; 1617 } 1618 } 1619 return true; 1620 } 1621 1622 /* Get a unique fsid for the layer */ 1623 static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path) 1624 { 1625 struct super_block *sb = path->mnt->mnt_sb; 1626 unsigned int i; 1627 dev_t dev; 1628 int err; 1629 bool bad_uuid = false; 1630 bool warn = false; 1631 1632 for (i = 0; i < ofs->numfs; i++) { 1633 if (ofs->fs[i].sb == sb) 1634 return i; 1635 } 1636 1637 if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) { 1638 bad_uuid = true; 1639 if (ofs->config.xino == OVL_XINO_AUTO) { 1640 ofs->config.xino = OVL_XINO_OFF; 1641 warn = true; 1642 } 1643 if (ofs->config.index || ofs->config.nfs_export) { 1644 ofs->config.index = false; 1645 ofs->config.nfs_export = false; 1646 warn = true; 1647 } 1648 if (warn) { 1649 pr_warn("%s uuid detected in lower fs '%pd2', falling back to xino=%s,index=off,nfs_export=off.\n", 1650 uuid_is_null(&sb->s_uuid) ? "null" : 1651 "conflicting", 1652 path->dentry, ovl_xino_str[ofs->config.xino]); 1653 } 1654 } 1655 1656 err = get_anon_bdev(&dev); 1657 if (err) { 1658 pr_err("failed to get anonymous bdev for lowerpath\n"); 1659 return err; 1660 } 1661 1662 ofs->fs[ofs->numfs].sb = sb; 1663 ofs->fs[ofs->numfs].pseudo_dev = dev; 1664 ofs->fs[ofs->numfs].bad_uuid = bad_uuid; 1665 1666 return ofs->numfs++; 1667 } 1668 1669 static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, 1670 struct path *stack, unsigned int numlower, 1671 struct ovl_layer *layers) 1672 { 1673 int err; 1674 unsigned int i; 1675 1676 err = -ENOMEM; 1677 ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL); 1678 if (ofs->fs == NULL) 1679 goto out; 1680 1681 /* idx/fsid 0 are reserved for upper fs even with lower only overlay */ 1682 ofs->numfs++; 1683 1684 /* 1685 * All lower layers that share the same fs as upper layer, use the same 1686 * pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower 1687 * only overlay to simplify ovl_fs_free(). 1688 * is_lower will be set if upper fs is shared with a lower layer. 1689 */ 1690 err = get_anon_bdev(&ofs->fs[0].pseudo_dev); 1691 if (err) { 1692 pr_err("failed to get anonymous bdev for upper fs\n"); 1693 goto out; 1694 } 1695 1696 if (ovl_upper_mnt(ofs)) { 1697 ofs->fs[0].sb = ovl_upper_mnt(ofs)->mnt_sb; 1698 ofs->fs[0].is_lower = false; 1699 } 1700 1701 for (i = 0; i < numlower; i++) { 1702 struct vfsmount *mnt; 1703 struct inode *trap; 1704 int fsid; 1705 1706 err = fsid = ovl_get_fsid(ofs, &stack[i]); 1707 if (err < 0) 1708 goto out; 1709 1710 /* 1711 * Check if lower root conflicts with this overlay layers before 1712 * checking if it is in-use as upperdir/workdir of "another" 1713 * mount, because we do not bother to check in ovl_is_inuse() if 1714 * the upperdir/workdir is in fact in-use by our 1715 * upperdir/workdir. 1716 */ 1717 err = ovl_setup_trap(sb, stack[i].dentry, &trap, "lowerdir"); 1718 if (err) 1719 goto out; 1720 1721 if (ovl_is_inuse(stack[i].dentry)) { 1722 err = ovl_report_in_use(ofs, "lowerdir"); 1723 if (err) { 1724 iput(trap); 1725 goto out; 1726 } 1727 } 1728 1729 mnt = clone_private_mount(&stack[i]); 1730 err = PTR_ERR(mnt); 1731 if (IS_ERR(mnt)) { 1732 pr_err("failed to clone lowerpath\n"); 1733 iput(trap); 1734 goto out; 1735 } 1736 1737 /* 1738 * Make lower layers R/O. That way fchmod/fchown on lower file 1739 * will fail instead of modifying lower fs. 1740 */ 1741 mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; 1742 1743 layers[ofs->numlayer].trap = trap; 1744 layers[ofs->numlayer].mnt = mnt; 1745 layers[ofs->numlayer].idx = ofs->numlayer; 1746 layers[ofs->numlayer].fsid = fsid; 1747 layers[ofs->numlayer].fs = &ofs->fs[fsid]; 1748 ofs->numlayer++; 1749 ofs->fs[fsid].is_lower = true; 1750 } 1751 1752 /* 1753 * When all layers on same fs, overlay can use real inode numbers. 1754 * With mount option "xino=<on|auto>", mounter declares that there are 1755 * enough free high bits in underlying fs to hold the unique fsid. 1756 * If overlayfs does encounter underlying inodes using the high xino 1757 * bits reserved for fsid, it emits a warning and uses the original 1758 * inode number or a non persistent inode number allocated from a 1759 * dedicated range. 1760 */ 1761 if (ofs->numfs - !ovl_upper_mnt(ofs) == 1) { 1762 if (ofs->config.xino == OVL_XINO_ON) 1763 pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n"); 1764 ofs->xino_mode = 0; 1765 } else if (ofs->config.xino == OVL_XINO_OFF) { 1766 ofs->xino_mode = -1; 1767 } else if (ofs->xino_mode < 0) { 1768 /* 1769 * This is a roundup of number of bits needed for encoding 1770 * fsid, where fsid 0 is reserved for upper fs (even with 1771 * lower only overlay) +1 extra bit is reserved for the non 1772 * persistent inode number range that is used for resolving 1773 * xino lower bits overflow. 1774 */ 1775 BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 30); 1776 ofs->xino_mode = ilog2(ofs->numfs - 1) + 2; 1777 } 1778 1779 if (ofs->xino_mode > 0) { 1780 pr_info("\"xino\" feature enabled using %d upper inode bits.\n", 1781 ofs->xino_mode); 1782 } 1783 1784 err = 0; 1785 out: 1786 return err; 1787 } 1788 1789 static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, 1790 const char *lower, unsigned int numlower, 1791 struct ovl_fs *ofs, struct ovl_layer *layers) 1792 { 1793 int err; 1794 struct path *stack = NULL; 1795 unsigned int i; 1796 struct ovl_entry *oe; 1797 1798 if (!ofs->config.upperdir && numlower == 1) { 1799 pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n"); 1800 return ERR_PTR(-EINVAL); 1801 } 1802 1803 stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL); 1804 if (!stack) 1805 return ERR_PTR(-ENOMEM); 1806 1807 err = -EINVAL; 1808 for (i = 0; i < numlower; i++) { 1809 err = ovl_lower_dir(lower, &stack[i], ofs, &sb->s_stack_depth); 1810 if (err) 1811 goto out_err; 1812 1813 lower = strchr(lower, '\0') + 1; 1814 } 1815 1816 err = -EINVAL; 1817 sb->s_stack_depth++; 1818 if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { 1819 pr_err("maximum fs stacking depth exceeded\n"); 1820 goto out_err; 1821 } 1822 1823 err = ovl_get_layers(sb, ofs, stack, numlower, layers); 1824 if (err) 1825 goto out_err; 1826 1827 err = -ENOMEM; 1828 oe = ovl_alloc_entry(numlower); 1829 if (!oe) 1830 goto out_err; 1831 1832 for (i = 0; i < numlower; i++) { 1833 oe->lowerstack[i].dentry = dget(stack[i].dentry); 1834 oe->lowerstack[i].layer = &ofs->layers[i+1]; 1835 } 1836 1837 out: 1838 for (i = 0; i < numlower; i++) 1839 path_put(&stack[i]); 1840 kfree(stack); 1841 1842 return oe; 1843 1844 out_err: 1845 oe = ERR_PTR(err); 1846 goto out; 1847 } 1848 1849 /* 1850 * Check if this layer root is a descendant of: 1851 * - another layer of this overlayfs instance 1852 * - upper/work dir of any overlayfs instance 1853 */ 1854 static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs, 1855 struct dentry *dentry, const char *name, 1856 bool is_lower) 1857 { 1858 struct dentry *next = dentry, *parent; 1859 int err = 0; 1860 1861 if (!dentry) 1862 return 0; 1863 1864 parent = dget_parent(next); 1865 1866 /* Walk back ancestors to root (inclusive) looking for traps */ 1867 while (!err && parent != next) { 1868 if (is_lower && ovl_lookup_trap_inode(sb, parent)) { 1869 err = -ELOOP; 1870 pr_err("overlapping %s path\n", name); 1871 } else if (ovl_is_inuse(parent)) { 1872 err = ovl_report_in_use(ofs, name); 1873 } 1874 next = parent; 1875 parent = dget_parent(next); 1876 dput(next); 1877 } 1878 1879 dput(parent); 1880 1881 return err; 1882 } 1883 1884 /* 1885 * Check if any of the layers or work dirs overlap. 1886 */ 1887 static int ovl_check_overlapping_layers(struct super_block *sb, 1888 struct ovl_fs *ofs) 1889 { 1890 int i, err; 1891 1892 if (ovl_upper_mnt(ofs)) { 1893 err = ovl_check_layer(sb, ofs, ovl_upper_mnt(ofs)->mnt_root, 1894 "upperdir", false); 1895 if (err) 1896 return err; 1897 1898 /* 1899 * Checking workbasedir avoids hitting ovl_is_inuse(parent) of 1900 * this instance and covers overlapping work and index dirs, 1901 * unless work or index dir have been moved since created inside 1902 * workbasedir. In that case, we already have their traps in 1903 * inode cache and we will catch that case on lookup. 1904 */ 1905 err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir", 1906 false); 1907 if (err) 1908 return err; 1909 } 1910 1911 for (i = 1; i < ofs->numlayer; i++) { 1912 err = ovl_check_layer(sb, ofs, 1913 ofs->layers[i].mnt->mnt_root, 1914 "lowerdir", true); 1915 if (err) 1916 return err; 1917 } 1918 1919 return 0; 1920 } 1921 1922 static struct dentry *ovl_get_root(struct super_block *sb, 1923 struct dentry *upperdentry, 1924 struct ovl_entry *oe) 1925 { 1926 struct dentry *root; 1927 struct ovl_path *lowerpath = &oe->lowerstack[0]; 1928 unsigned long ino = d_inode(lowerpath->dentry)->i_ino; 1929 int fsid = lowerpath->layer->fsid; 1930 struct ovl_inode_params oip = { 1931 .upperdentry = upperdentry, 1932 .lowerpath = lowerpath, 1933 }; 1934 1935 root = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); 1936 if (!root) 1937 return NULL; 1938 1939 root->d_fsdata = oe; 1940 1941 if (upperdentry) { 1942 /* Root inode uses upper st_ino/i_ino */ 1943 ino = d_inode(upperdentry)->i_ino; 1944 fsid = 0; 1945 ovl_dentry_set_upper_alias(root); 1946 if (ovl_is_impuredir(sb, upperdentry)) 1947 ovl_set_flag(OVL_IMPURE, d_inode(root)); 1948 } 1949 1950 /* Root is always merge -> can have whiteouts */ 1951 ovl_set_flag(OVL_WHITEOUTS, d_inode(root)); 1952 ovl_dentry_set_flag(OVL_E_CONNECTED, root); 1953 ovl_set_upperdata(d_inode(root)); 1954 ovl_inode_init(d_inode(root), &oip, ino, fsid); 1955 ovl_dentry_update_reval(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE); 1956 1957 return root; 1958 } 1959 1960 static int ovl_fill_super(struct super_block *sb, void *data, int silent) 1961 { 1962 struct path upperpath = { }; 1963 struct dentry *root_dentry; 1964 struct ovl_entry *oe; 1965 struct ovl_fs *ofs; 1966 struct ovl_layer *layers; 1967 struct cred *cred; 1968 char *splitlower = NULL; 1969 unsigned int numlower; 1970 int err; 1971 1972 err = -EIO; 1973 if (WARN_ON(sb->s_user_ns != current_user_ns())) 1974 goto out; 1975 1976 sb->s_d_op = &ovl_dentry_operations; 1977 1978 err = -ENOMEM; 1979 ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); 1980 if (!ofs) 1981 goto out; 1982 1983 err = -ENOMEM; 1984 ofs->creator_cred = cred = prepare_creds(); 1985 if (!cred) 1986 goto out_err; 1987 1988 /* Is there a reason anyone would want not to share whiteouts? */ 1989 ofs->share_whiteout = true; 1990 1991 ofs->config.index = ovl_index_def; 1992 ofs->config.uuid = true; 1993 ofs->config.nfs_export = ovl_nfs_export_def; 1994 ofs->config.xino = ovl_xino_def(); 1995 ofs->config.metacopy = ovl_metacopy_def; 1996 err = ovl_parse_opt((char *) data, &ofs->config); 1997 if (err) 1998 goto out_err; 1999 2000 err = -EINVAL; 2001 if (!ofs->config.lowerdir) { 2002 if (!silent) 2003 pr_err("missing 'lowerdir'\n"); 2004 goto out_err; 2005 } 2006 2007 err = -ENOMEM; 2008 splitlower = kstrdup(ofs->config.lowerdir, GFP_KERNEL); 2009 if (!splitlower) 2010 goto out_err; 2011 2012 err = -EINVAL; 2013 numlower = ovl_split_lowerdirs(splitlower); 2014 if (numlower > OVL_MAX_STACK) { 2015 pr_err("too many lower directories, limit is %d\n", 2016 OVL_MAX_STACK); 2017 goto out_err; 2018 } 2019 2020 err = -ENOMEM; 2021 layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL); 2022 if (!layers) 2023 goto out_err; 2024 2025 ofs->layers = layers; 2026 /* Layer 0 is reserved for upper even if there's no upper */ 2027 ofs->numlayer = 1; 2028 2029 sb->s_stack_depth = 0; 2030 sb->s_maxbytes = MAX_LFS_FILESIZE; 2031 atomic_long_set(&ofs->last_ino, 1); 2032 /* Assume underlaying fs uses 32bit inodes unless proven otherwise */ 2033 if (ofs->config.xino != OVL_XINO_OFF) { 2034 ofs->xino_mode = BITS_PER_LONG - 32; 2035 if (!ofs->xino_mode) { 2036 pr_warn("xino not supported on 32bit kernel, falling back to xino=off.\n"); 2037 ofs->config.xino = OVL_XINO_OFF; 2038 } 2039 } 2040 2041 /* alloc/destroy_inode needed for setting up traps in inode cache */ 2042 sb->s_op = &ovl_super_operations; 2043 2044 if (ofs->config.upperdir) { 2045 struct super_block *upper_sb; 2046 2047 err = -EINVAL; 2048 if (!ofs->config.workdir) { 2049 pr_err("missing 'workdir'\n"); 2050 goto out_err; 2051 } 2052 2053 err = ovl_get_upper(sb, ofs, &layers[0], &upperpath); 2054 if (err) 2055 goto out_err; 2056 2057 upper_sb = ovl_upper_mnt(ofs)->mnt_sb; 2058 if (!ovl_should_sync(ofs)) { 2059 ofs->errseq = errseq_sample(&upper_sb->s_wb_err); 2060 if (errseq_check(&upper_sb->s_wb_err, ofs->errseq)) { 2061 err = -EIO; 2062 pr_err("Cannot mount volatile when upperdir has an unseen error. Sync upperdir fs to clear state.\n"); 2063 goto out_err; 2064 } 2065 } 2066 2067 err = ovl_get_workdir(sb, ofs, &upperpath); 2068 if (err) 2069 goto out_err; 2070 2071 if (!ofs->workdir) 2072 sb->s_flags |= SB_RDONLY; 2073 2074 sb->s_stack_depth = upper_sb->s_stack_depth; 2075 sb->s_time_gran = upper_sb->s_time_gran; 2076 } 2077 oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers); 2078 err = PTR_ERR(oe); 2079 if (IS_ERR(oe)) 2080 goto out_err; 2081 2082 /* If the upper fs is nonexistent, we mark overlayfs r/o too */ 2083 if (!ovl_upper_mnt(ofs)) 2084 sb->s_flags |= SB_RDONLY; 2085 2086 if (!ofs->config.uuid && ofs->numfs > 1) { 2087 pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=on.\n"); 2088 ofs->config.uuid = true; 2089 } 2090 2091 if (!ovl_force_readonly(ofs) && ofs->config.index) { 2092 err = ovl_get_indexdir(sb, ofs, oe, &upperpath); 2093 if (err) 2094 goto out_free_oe; 2095 2096 /* Force r/o mount with no index dir */ 2097 if (!ofs->indexdir) 2098 sb->s_flags |= SB_RDONLY; 2099 } 2100 2101 err = ovl_check_overlapping_layers(sb, ofs); 2102 if (err) 2103 goto out_free_oe; 2104 2105 /* Show index=off in /proc/mounts for forced r/o mount */ 2106 if (!ofs->indexdir) { 2107 ofs->config.index = false; 2108 if (ovl_upper_mnt(ofs) && ofs->config.nfs_export) { 2109 pr_warn("NFS export requires an index dir, falling back to nfs_export=off.\n"); 2110 ofs->config.nfs_export = false; 2111 } 2112 } 2113 2114 if (ofs->config.metacopy && ofs->config.nfs_export) { 2115 pr_warn("NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n"); 2116 ofs->config.nfs_export = false; 2117 } 2118 2119 if (ofs->config.nfs_export) 2120 sb->s_export_op = &ovl_export_operations; 2121 2122 /* Never override disk quota limits or use reserved space */ 2123 cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); 2124 2125 sb->s_magic = OVERLAYFS_SUPER_MAGIC; 2126 sb->s_xattr = ofs->config.userxattr ? ovl_user_xattr_handlers : 2127 ovl_trusted_xattr_handlers; 2128 sb->s_fs_info = ofs; 2129 sb->s_flags |= SB_POSIXACL; 2130 sb->s_iflags |= SB_I_SKIP_SYNC; 2131 2132 err = -ENOMEM; 2133 root_dentry = ovl_get_root(sb, upperpath.dentry, oe); 2134 if (!root_dentry) 2135 goto out_free_oe; 2136 2137 mntput(upperpath.mnt); 2138 kfree(splitlower); 2139 2140 sb->s_root = root_dentry; 2141 2142 return 0; 2143 2144 out_free_oe: 2145 ovl_entry_stack_free(oe); 2146 kfree(oe); 2147 out_err: 2148 kfree(splitlower); 2149 path_put(&upperpath); 2150 ovl_free_fs(ofs); 2151 out: 2152 return err; 2153 } 2154 2155 static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, 2156 const char *dev_name, void *raw_data) 2157 { 2158 return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); 2159 } 2160 2161 static struct file_system_type ovl_fs_type = { 2162 .owner = THIS_MODULE, 2163 .name = "overlay", 2164 .fs_flags = FS_USERNS_MOUNT, 2165 .mount = ovl_mount, 2166 .kill_sb = kill_anon_super, 2167 }; 2168 MODULE_ALIAS_FS("overlay"); 2169 2170 static void ovl_inode_init_once(void *foo) 2171 { 2172 struct ovl_inode *oi = foo; 2173 2174 inode_init_once(&oi->vfs_inode); 2175 } 2176 2177 static int __init ovl_init(void) 2178 { 2179 int err; 2180 2181 ovl_inode_cachep = kmem_cache_create("ovl_inode", 2182 sizeof(struct ovl_inode), 0, 2183 (SLAB_RECLAIM_ACCOUNT| 2184 SLAB_MEM_SPREAD|SLAB_ACCOUNT), 2185 ovl_inode_init_once); 2186 if (ovl_inode_cachep == NULL) 2187 return -ENOMEM; 2188 2189 err = ovl_aio_request_cache_init(); 2190 if (!err) { 2191 err = register_filesystem(&ovl_fs_type); 2192 if (!err) 2193 return 0; 2194 2195 ovl_aio_request_cache_destroy(); 2196 } 2197 kmem_cache_destroy(ovl_inode_cachep); 2198 2199 return err; 2200 } 2201 2202 static void __exit ovl_exit(void) 2203 { 2204 unregister_filesystem(&ovl_fs_type); 2205 2206 /* 2207 * Make sure all delayed rcu free inodes are flushed before we 2208 * destroy cache. 2209 */ 2210 rcu_barrier(); 2211 kmem_cache_destroy(ovl_inode_cachep); 2212 ovl_aio_request_cache_destroy(); 2213 } 2214 2215 module_init(ovl_init); 2216 module_exit(ovl_exit); 2217