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 = alloc_inode_sb(sb, 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 err = ovl_mkdir_real(dir, &work, attr.ia_mode); 791 if (err) 792 goto out_dput; 793 794 /* Weird filesystem returning with hashed negative (kernfs)? */ 795 err = -EINVAL; 796 if (d_really_is_negative(work)) 797 goto out_dput; 798 799 /* 800 * Try to remove POSIX ACL xattrs from workdir. We are good if: 801 * 802 * a) success (there was a POSIX ACL xattr and was removed) 803 * b) -ENODATA (there was no POSIX ACL xattr) 804 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported) 805 * 806 * There are various other error values that could effectively 807 * mean that the xattr doesn't exist (e.g. -ERANGE is returned 808 * if the xattr name is too long), but the set of filesystems 809 * allowed as upper are limited to "normal" ones, where checking 810 * for the above two errors is sufficient. 811 */ 812 err = vfs_removexattr(&init_user_ns, work, 813 XATTR_NAME_POSIX_ACL_DEFAULT); 814 if (err && err != -ENODATA && err != -EOPNOTSUPP) 815 goto out_dput; 816 817 err = vfs_removexattr(&init_user_ns, work, 818 XATTR_NAME_POSIX_ACL_ACCESS); 819 if (err && err != -ENODATA && err != -EOPNOTSUPP) 820 goto out_dput; 821 822 /* Clear any inherited mode bits */ 823 inode_lock(work->d_inode); 824 err = notify_change(&init_user_ns, work, &attr, NULL); 825 inode_unlock(work->d_inode); 826 if (err) 827 goto out_dput; 828 } else { 829 err = PTR_ERR(work); 830 goto out_err; 831 } 832 out_unlock: 833 inode_unlock(dir); 834 return work; 835 836 out_dput: 837 dput(work); 838 out_err: 839 pr_warn("failed to create directory %s/%s (errno: %i); mounting read-only\n", 840 ofs->config.workdir, name, -err); 841 work = NULL; 842 goto out_unlock; 843 } 844 845 static void ovl_unescape(char *s) 846 { 847 char *d = s; 848 849 for (;; s++, d++) { 850 if (*s == '\\') 851 s++; 852 *d = *s; 853 if (!*s) 854 break; 855 } 856 } 857 858 static int ovl_mount_dir_noesc(const char *name, struct path *path) 859 { 860 int err = -EINVAL; 861 862 if (!*name) { 863 pr_err("empty lowerdir\n"); 864 goto out; 865 } 866 err = kern_path(name, LOOKUP_FOLLOW, path); 867 if (err) { 868 pr_err("failed to resolve '%s': %i\n", name, err); 869 goto out; 870 } 871 err = -EINVAL; 872 if (ovl_dentry_weird(path->dentry)) { 873 pr_err("filesystem on '%s' not supported\n", name); 874 goto out_put; 875 } 876 if (is_idmapped_mnt(path->mnt)) { 877 pr_err("idmapped layers are currently not supported\n"); 878 goto out_put; 879 } 880 if (!d_is_dir(path->dentry)) { 881 pr_err("'%s' not a directory\n", name); 882 goto out_put; 883 } 884 return 0; 885 886 out_put: 887 path_put_init(path); 888 out: 889 return err; 890 } 891 892 static int ovl_mount_dir(const char *name, struct path *path) 893 { 894 int err = -ENOMEM; 895 char *tmp = kstrdup(name, GFP_KERNEL); 896 897 if (tmp) { 898 ovl_unescape(tmp); 899 err = ovl_mount_dir_noesc(tmp, path); 900 901 if (!err && path->dentry->d_flags & DCACHE_OP_REAL) { 902 pr_err("filesystem on '%s' not supported as upperdir\n", 903 tmp); 904 path_put_init(path); 905 err = -EINVAL; 906 } 907 kfree(tmp); 908 } 909 return err; 910 } 911 912 static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs, 913 const char *name) 914 { 915 struct kstatfs statfs; 916 int err = vfs_statfs(path, &statfs); 917 918 if (err) 919 pr_err("statfs failed on '%s'\n", name); 920 else 921 ofs->namelen = max(ofs->namelen, statfs.f_namelen); 922 923 return err; 924 } 925 926 static int ovl_lower_dir(const char *name, struct path *path, 927 struct ovl_fs *ofs, int *stack_depth) 928 { 929 int fh_type; 930 int err; 931 932 err = ovl_mount_dir_noesc(name, path); 933 if (err) 934 return err; 935 936 err = ovl_check_namelen(path, ofs, name); 937 if (err) 938 return err; 939 940 *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); 941 942 /* 943 * The inodes index feature and NFS export need to encode and decode 944 * file handles, so they require that all layers support them. 945 */ 946 fh_type = ovl_can_decode_fh(path->dentry->d_sb); 947 if ((ofs->config.nfs_export || 948 (ofs->config.index && ofs->config.upperdir)) && !fh_type) { 949 ofs->config.index = false; 950 ofs->config.nfs_export = false; 951 pr_warn("fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n", 952 name); 953 } 954 /* 955 * Decoding origin file handle is required for persistent st_ino. 956 * Without persistent st_ino, xino=auto falls back to xino=off. 957 */ 958 if (ofs->config.xino == OVL_XINO_AUTO && 959 ofs->config.upperdir && !fh_type) { 960 ofs->config.xino = OVL_XINO_OFF; 961 pr_warn("fs on '%s' does not support file handles, falling back to xino=off.\n", 962 name); 963 } 964 965 /* Check if lower fs has 32bit inode numbers */ 966 if (fh_type != FILEID_INO32_GEN) 967 ofs->xino_mode = -1; 968 969 return 0; 970 } 971 972 /* Workdir should not be subdir of upperdir and vice versa */ 973 static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) 974 { 975 bool ok = false; 976 977 if (workdir != upperdir) { 978 ok = (lock_rename(workdir, upperdir) == NULL); 979 unlock_rename(workdir, upperdir); 980 } 981 return ok; 982 } 983 984 static unsigned int ovl_split_lowerdirs(char *str) 985 { 986 unsigned int ctr = 1; 987 char *s, *d; 988 989 for (s = d = str;; s++, d++) { 990 if (*s == '\\') { 991 s++; 992 } else if (*s == ':') { 993 *d = '\0'; 994 ctr++; 995 continue; 996 } 997 *d = *s; 998 if (!*s) 999 break; 1000 } 1001 return ctr; 1002 } 1003 1004 static int __maybe_unused 1005 ovl_posix_acl_xattr_get(const struct xattr_handler *handler, 1006 struct dentry *dentry, struct inode *inode, 1007 const char *name, void *buffer, size_t size) 1008 { 1009 return ovl_xattr_get(dentry, inode, handler->name, buffer, size); 1010 } 1011 1012 static int __maybe_unused 1013 ovl_posix_acl_xattr_set(const struct xattr_handler *handler, 1014 struct user_namespace *mnt_userns, 1015 struct dentry *dentry, struct inode *inode, 1016 const char *name, const void *value, 1017 size_t size, int flags) 1018 { 1019 struct dentry *workdir = ovl_workdir(dentry); 1020 struct inode *realinode = ovl_inode_real(inode); 1021 struct posix_acl *acl = NULL; 1022 int err; 1023 1024 /* Check that everything is OK before copy-up */ 1025 if (value) { 1026 acl = posix_acl_from_xattr(&init_user_ns, value, size); 1027 if (IS_ERR(acl)) 1028 return PTR_ERR(acl); 1029 } 1030 err = -EOPNOTSUPP; 1031 if (!IS_POSIXACL(d_inode(workdir))) 1032 goto out_acl_release; 1033 if (!realinode->i_op->set_acl) 1034 goto out_acl_release; 1035 if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) { 1036 err = acl ? -EACCES : 0; 1037 goto out_acl_release; 1038 } 1039 err = -EPERM; 1040 if (!inode_owner_or_capable(&init_user_ns, inode)) 1041 goto out_acl_release; 1042 1043 posix_acl_release(acl); 1044 1045 /* 1046 * Check if sgid bit needs to be cleared (actual setacl operation will 1047 * be done with mounter's capabilities and so that won't do it for us). 1048 */ 1049 if (unlikely(inode->i_mode & S_ISGID) && 1050 handler->flags == ACL_TYPE_ACCESS && 1051 !in_group_p(inode->i_gid) && 1052 !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID)) { 1053 struct iattr iattr = { .ia_valid = ATTR_KILL_SGID }; 1054 1055 err = ovl_setattr(&init_user_ns, dentry, &iattr); 1056 if (err) 1057 return err; 1058 } 1059 1060 err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags); 1061 return err; 1062 1063 out_acl_release: 1064 posix_acl_release(acl); 1065 return err; 1066 } 1067 1068 static int ovl_own_xattr_get(const struct xattr_handler *handler, 1069 struct dentry *dentry, struct inode *inode, 1070 const char *name, void *buffer, size_t size) 1071 { 1072 return -EOPNOTSUPP; 1073 } 1074 1075 static int ovl_own_xattr_set(const struct xattr_handler *handler, 1076 struct user_namespace *mnt_userns, 1077 struct dentry *dentry, struct inode *inode, 1078 const char *name, const void *value, 1079 size_t size, int flags) 1080 { 1081 return -EOPNOTSUPP; 1082 } 1083 1084 static int ovl_other_xattr_get(const struct xattr_handler *handler, 1085 struct dentry *dentry, struct inode *inode, 1086 const char *name, void *buffer, size_t size) 1087 { 1088 return ovl_xattr_get(dentry, inode, name, buffer, size); 1089 } 1090 1091 static int ovl_other_xattr_set(const struct xattr_handler *handler, 1092 struct user_namespace *mnt_userns, 1093 struct dentry *dentry, struct inode *inode, 1094 const char *name, const void *value, 1095 size_t size, int flags) 1096 { 1097 return ovl_xattr_set(dentry, inode, name, value, size, flags); 1098 } 1099 1100 static const struct xattr_handler __maybe_unused 1101 ovl_posix_acl_access_xattr_handler = { 1102 .name = XATTR_NAME_POSIX_ACL_ACCESS, 1103 .flags = ACL_TYPE_ACCESS, 1104 .get = ovl_posix_acl_xattr_get, 1105 .set = ovl_posix_acl_xattr_set, 1106 }; 1107 1108 static const struct xattr_handler __maybe_unused 1109 ovl_posix_acl_default_xattr_handler = { 1110 .name = XATTR_NAME_POSIX_ACL_DEFAULT, 1111 .flags = ACL_TYPE_DEFAULT, 1112 .get = ovl_posix_acl_xattr_get, 1113 .set = ovl_posix_acl_xattr_set, 1114 }; 1115 1116 static const struct xattr_handler ovl_own_trusted_xattr_handler = { 1117 .prefix = OVL_XATTR_TRUSTED_PREFIX, 1118 .get = ovl_own_xattr_get, 1119 .set = ovl_own_xattr_set, 1120 }; 1121 1122 static const struct xattr_handler ovl_own_user_xattr_handler = { 1123 .prefix = OVL_XATTR_USER_PREFIX, 1124 .get = ovl_own_xattr_get, 1125 .set = ovl_own_xattr_set, 1126 }; 1127 1128 static const struct xattr_handler ovl_other_xattr_handler = { 1129 .prefix = "", /* catch all */ 1130 .get = ovl_other_xattr_get, 1131 .set = ovl_other_xattr_set, 1132 }; 1133 1134 static const struct xattr_handler *ovl_trusted_xattr_handlers[] = { 1135 #ifdef CONFIG_FS_POSIX_ACL 1136 &ovl_posix_acl_access_xattr_handler, 1137 &ovl_posix_acl_default_xattr_handler, 1138 #endif 1139 &ovl_own_trusted_xattr_handler, 1140 &ovl_other_xattr_handler, 1141 NULL 1142 }; 1143 1144 static const struct xattr_handler *ovl_user_xattr_handlers[] = { 1145 #ifdef CONFIG_FS_POSIX_ACL 1146 &ovl_posix_acl_access_xattr_handler, 1147 &ovl_posix_acl_default_xattr_handler, 1148 #endif 1149 &ovl_own_user_xattr_handler, 1150 &ovl_other_xattr_handler, 1151 NULL 1152 }; 1153 1154 static int ovl_setup_trap(struct super_block *sb, struct dentry *dir, 1155 struct inode **ptrap, const char *name) 1156 { 1157 struct inode *trap; 1158 int err; 1159 1160 trap = ovl_get_trap_inode(sb, dir); 1161 err = PTR_ERR_OR_ZERO(trap); 1162 if (err) { 1163 if (err == -ELOOP) 1164 pr_err("conflicting %s path\n", name); 1165 return err; 1166 } 1167 1168 *ptrap = trap; 1169 return 0; 1170 } 1171 1172 /* 1173 * Determine how we treat concurrent use of upperdir/workdir based on the 1174 * index feature. This is papering over mount leaks of container runtimes, 1175 * for example, an old overlay mount is leaked and now its upperdir is 1176 * attempted to be used as a lower layer in a new overlay mount. 1177 */ 1178 static int ovl_report_in_use(struct ovl_fs *ofs, const char *name) 1179 { 1180 if (ofs->config.index) { 1181 pr_err("%s is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.\n", 1182 name); 1183 return -EBUSY; 1184 } else { 1185 pr_warn("%s is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.\n", 1186 name); 1187 return 0; 1188 } 1189 } 1190 1191 static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, 1192 struct ovl_layer *upper_layer, struct path *upperpath) 1193 { 1194 struct vfsmount *upper_mnt; 1195 int err; 1196 1197 err = ovl_mount_dir(ofs->config.upperdir, upperpath); 1198 if (err) 1199 goto out; 1200 1201 /* Upperdir path should not be r/o */ 1202 if (__mnt_is_readonly(upperpath->mnt)) { 1203 pr_err("upper fs is r/o, try multi-lower layers mount\n"); 1204 err = -EINVAL; 1205 goto out; 1206 } 1207 1208 err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir); 1209 if (err) 1210 goto out; 1211 1212 err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap, 1213 "upperdir"); 1214 if (err) 1215 goto out; 1216 1217 upper_mnt = clone_private_mount(upperpath); 1218 err = PTR_ERR(upper_mnt); 1219 if (IS_ERR(upper_mnt)) { 1220 pr_err("failed to clone upperpath\n"); 1221 goto out; 1222 } 1223 1224 /* Don't inherit atime flags */ 1225 upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); 1226 upper_layer->mnt = upper_mnt; 1227 upper_layer->idx = 0; 1228 upper_layer->fsid = 0; 1229 1230 /* 1231 * Inherit SB_NOSEC flag from upperdir. 1232 * 1233 * This optimization changes behavior when a security related attribute 1234 * (suid/sgid/security.*) is changed on an underlying layer. This is 1235 * okay because we don't yet have guarantees in that case, but it will 1236 * need careful treatment once we want to honour changes to underlying 1237 * filesystems. 1238 */ 1239 if (upper_mnt->mnt_sb->s_flags & SB_NOSEC) 1240 sb->s_flags |= SB_NOSEC; 1241 1242 if (ovl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root)) { 1243 ofs->upperdir_locked = true; 1244 } else { 1245 err = ovl_report_in_use(ofs, "upperdir"); 1246 if (err) 1247 goto out; 1248 } 1249 1250 err = 0; 1251 out: 1252 return err; 1253 } 1254 1255 /* 1256 * Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and 1257 * negative values if error is encountered. 1258 */ 1259 static int ovl_check_rename_whiteout(struct dentry *workdir) 1260 { 1261 struct inode *dir = d_inode(workdir); 1262 struct dentry *temp; 1263 struct dentry *dest; 1264 struct dentry *whiteout; 1265 struct name_snapshot name; 1266 int err; 1267 1268 inode_lock_nested(dir, I_MUTEX_PARENT); 1269 1270 temp = ovl_create_temp(workdir, OVL_CATTR(S_IFREG | 0)); 1271 err = PTR_ERR(temp); 1272 if (IS_ERR(temp)) 1273 goto out_unlock; 1274 1275 dest = ovl_lookup_temp(workdir); 1276 err = PTR_ERR(dest); 1277 if (IS_ERR(dest)) { 1278 dput(temp); 1279 goto out_unlock; 1280 } 1281 1282 /* Name is inline and stable - using snapshot as a copy helper */ 1283 take_dentry_name_snapshot(&name, temp); 1284 err = ovl_do_rename(dir, temp, dir, dest, RENAME_WHITEOUT); 1285 if (err) { 1286 if (err == -EINVAL) 1287 err = 0; 1288 goto cleanup_temp; 1289 } 1290 1291 whiteout = lookup_one_len(name.name.name, workdir, name.name.len); 1292 err = PTR_ERR(whiteout); 1293 if (IS_ERR(whiteout)) 1294 goto cleanup_temp; 1295 1296 err = ovl_is_whiteout(whiteout); 1297 1298 /* Best effort cleanup of whiteout and temp file */ 1299 if (err) 1300 ovl_cleanup(dir, whiteout); 1301 dput(whiteout); 1302 1303 cleanup_temp: 1304 ovl_cleanup(dir, temp); 1305 release_dentry_name_snapshot(&name); 1306 dput(temp); 1307 dput(dest); 1308 1309 out_unlock: 1310 inode_unlock(dir); 1311 1312 return err; 1313 } 1314 1315 static struct dentry *ovl_lookup_or_create(struct dentry *parent, 1316 const char *name, umode_t mode) 1317 { 1318 size_t len = strlen(name); 1319 struct dentry *child; 1320 1321 inode_lock_nested(parent->d_inode, I_MUTEX_PARENT); 1322 child = lookup_one_len(name, parent, len); 1323 if (!IS_ERR(child) && !child->d_inode) 1324 child = ovl_create_real(parent->d_inode, child, 1325 OVL_CATTR(mode)); 1326 inode_unlock(parent->d_inode); 1327 dput(parent); 1328 1329 return child; 1330 } 1331 1332 /* 1333 * Creates $workdir/work/incompat/volatile/dirty file if it is not already 1334 * present. 1335 */ 1336 static int ovl_create_volatile_dirty(struct ovl_fs *ofs) 1337 { 1338 unsigned int ctr; 1339 struct dentry *d = dget(ofs->workbasedir); 1340 static const char *const volatile_path[] = { 1341 OVL_WORKDIR_NAME, "incompat", "volatile", "dirty" 1342 }; 1343 const char *const *name = volatile_path; 1344 1345 for (ctr = ARRAY_SIZE(volatile_path); ctr; ctr--, name++) { 1346 d = ovl_lookup_or_create(d, *name, ctr > 1 ? S_IFDIR : S_IFREG); 1347 if (IS_ERR(d)) 1348 return PTR_ERR(d); 1349 } 1350 dput(d); 1351 return 0; 1352 } 1353 1354 static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs, 1355 struct path *workpath) 1356 { 1357 struct vfsmount *mnt = ovl_upper_mnt(ofs); 1358 struct dentry *temp, *workdir; 1359 bool rename_whiteout; 1360 bool d_type; 1361 int fh_type; 1362 int err; 1363 1364 err = mnt_want_write(mnt); 1365 if (err) 1366 return err; 1367 1368 workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false); 1369 err = PTR_ERR(workdir); 1370 if (IS_ERR_OR_NULL(workdir)) 1371 goto out; 1372 1373 ofs->workdir = workdir; 1374 1375 err = ovl_setup_trap(sb, ofs->workdir, &ofs->workdir_trap, "workdir"); 1376 if (err) 1377 goto out; 1378 1379 /* 1380 * Upper should support d_type, else whiteouts are visible. Given 1381 * workdir and upper are on same fs, we can do iterate_dir() on 1382 * workdir. This check requires successful creation of workdir in 1383 * previous step. 1384 */ 1385 err = ovl_check_d_type_supported(workpath); 1386 if (err < 0) 1387 goto out; 1388 1389 d_type = err; 1390 if (!d_type) 1391 pr_warn("upper fs needs to support d_type.\n"); 1392 1393 /* Check if upper/work fs supports O_TMPFILE */ 1394 temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0); 1395 ofs->tmpfile = !IS_ERR(temp); 1396 if (ofs->tmpfile) 1397 dput(temp); 1398 else 1399 pr_warn("upper fs does not support tmpfile.\n"); 1400 1401 1402 /* Check if upper/work fs supports RENAME_WHITEOUT */ 1403 err = ovl_check_rename_whiteout(ofs->workdir); 1404 if (err < 0) 1405 goto out; 1406 1407 rename_whiteout = err; 1408 if (!rename_whiteout) 1409 pr_warn("upper fs does not support RENAME_WHITEOUT.\n"); 1410 1411 /* 1412 * Check if upper/work fs supports (trusted|user).overlay.* xattr 1413 */ 1414 err = ovl_do_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1); 1415 if (err) { 1416 ofs->noxattr = true; 1417 if (ofs->config.index || ofs->config.metacopy) { 1418 ofs->config.index = false; 1419 ofs->config.metacopy = false; 1420 pr_warn("upper fs does not support xattr, falling back to index=off,metacopy=off.\n"); 1421 } 1422 /* 1423 * xattr support is required for persistent st_ino. 1424 * Without persistent st_ino, xino=auto falls back to xino=off. 1425 */ 1426 if (ofs->config.xino == OVL_XINO_AUTO) { 1427 ofs->config.xino = OVL_XINO_OFF; 1428 pr_warn("upper fs does not support xattr, falling back to xino=off.\n"); 1429 } 1430 err = 0; 1431 } else { 1432 ovl_do_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE); 1433 } 1434 1435 /* 1436 * We allowed sub-optimal upper fs configuration and don't want to break 1437 * users over kernel upgrade, but we never allowed remote upper fs, so 1438 * we can enforce strict requirements for remote upper fs. 1439 */ 1440 if (ovl_dentry_remote(ofs->workdir) && 1441 (!d_type || !rename_whiteout || ofs->noxattr)) { 1442 pr_err("upper fs missing required features.\n"); 1443 err = -EINVAL; 1444 goto out; 1445 } 1446 1447 /* 1448 * For volatile mount, create a incompat/volatile/dirty file to keep 1449 * track of it. 1450 */ 1451 if (ofs->config.ovl_volatile) { 1452 err = ovl_create_volatile_dirty(ofs); 1453 if (err < 0) { 1454 pr_err("Failed to create volatile/dirty file.\n"); 1455 goto out; 1456 } 1457 } 1458 1459 /* Check if upper/work fs supports file handles */ 1460 fh_type = ovl_can_decode_fh(ofs->workdir->d_sb); 1461 if (ofs->config.index && !fh_type) { 1462 ofs->config.index = false; 1463 pr_warn("upper fs does not support file handles, falling back to index=off.\n"); 1464 } 1465 1466 /* Check if upper fs has 32bit inode numbers */ 1467 if (fh_type != FILEID_INO32_GEN) 1468 ofs->xino_mode = -1; 1469 1470 /* NFS export of r/w mount depends on index */ 1471 if (ofs->config.nfs_export && !ofs->config.index) { 1472 pr_warn("NFS export requires \"index=on\", falling back to nfs_export=off.\n"); 1473 ofs->config.nfs_export = false; 1474 } 1475 out: 1476 mnt_drop_write(mnt); 1477 return err; 1478 } 1479 1480 static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs, 1481 struct path *upperpath) 1482 { 1483 int err; 1484 struct path workpath = { }; 1485 1486 err = ovl_mount_dir(ofs->config.workdir, &workpath); 1487 if (err) 1488 goto out; 1489 1490 err = -EINVAL; 1491 if (upperpath->mnt != workpath.mnt) { 1492 pr_err("workdir and upperdir must reside under the same mount\n"); 1493 goto out; 1494 } 1495 if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) { 1496 pr_err("workdir and upperdir must be separate subtrees\n"); 1497 goto out; 1498 } 1499 1500 ofs->workbasedir = dget(workpath.dentry); 1501 1502 if (ovl_inuse_trylock(ofs->workbasedir)) { 1503 ofs->workdir_locked = true; 1504 } else { 1505 err = ovl_report_in_use(ofs, "workdir"); 1506 if (err) 1507 goto out; 1508 } 1509 1510 err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap, 1511 "workdir"); 1512 if (err) 1513 goto out; 1514 1515 err = ovl_make_workdir(sb, ofs, &workpath); 1516 1517 out: 1518 path_put(&workpath); 1519 1520 return err; 1521 } 1522 1523 static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs, 1524 struct ovl_entry *oe, struct path *upperpath) 1525 { 1526 struct vfsmount *mnt = ovl_upper_mnt(ofs); 1527 struct dentry *indexdir; 1528 int err; 1529 1530 err = mnt_want_write(mnt); 1531 if (err) 1532 return err; 1533 1534 /* Verify lower root is upper root origin */ 1535 err = ovl_verify_origin(ofs, upperpath->dentry, 1536 oe->lowerstack[0].dentry, true); 1537 if (err) { 1538 pr_err("failed to verify upper root origin\n"); 1539 goto out; 1540 } 1541 1542 /* index dir will act also as workdir */ 1543 iput(ofs->workdir_trap); 1544 ofs->workdir_trap = NULL; 1545 dput(ofs->workdir); 1546 ofs->workdir = NULL; 1547 indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true); 1548 if (IS_ERR(indexdir)) { 1549 err = PTR_ERR(indexdir); 1550 } else if (indexdir) { 1551 ofs->indexdir = indexdir; 1552 ofs->workdir = dget(indexdir); 1553 1554 err = ovl_setup_trap(sb, ofs->indexdir, &ofs->indexdir_trap, 1555 "indexdir"); 1556 if (err) 1557 goto out; 1558 1559 /* 1560 * Verify upper root is exclusively associated with index dir. 1561 * Older kernels stored upper fh in ".overlay.origin" 1562 * xattr. If that xattr exists, verify that it is a match to 1563 * upper dir file handle. In any case, verify or set xattr 1564 * ".overlay.upper" to indicate that index may have 1565 * directory entries. 1566 */ 1567 if (ovl_check_origin_xattr(ofs, ofs->indexdir)) { 1568 err = ovl_verify_set_fh(ofs, ofs->indexdir, 1569 OVL_XATTR_ORIGIN, 1570 upperpath->dentry, true, false); 1571 if (err) 1572 pr_err("failed to verify index dir 'origin' xattr\n"); 1573 } 1574 err = ovl_verify_upper(ofs, ofs->indexdir, upperpath->dentry, 1575 true); 1576 if (err) 1577 pr_err("failed to verify index dir 'upper' xattr\n"); 1578 1579 /* Cleanup bad/stale/orphan index entries */ 1580 if (!err) 1581 err = ovl_indexdir_cleanup(ofs); 1582 } 1583 if (err || !ofs->indexdir) 1584 pr_warn("try deleting index dir or mounting with '-o index=off' to disable inodes index.\n"); 1585 1586 out: 1587 mnt_drop_write(mnt); 1588 return err; 1589 } 1590 1591 static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid) 1592 { 1593 unsigned int i; 1594 1595 if (!ofs->config.nfs_export && !ovl_upper_mnt(ofs)) 1596 return true; 1597 1598 /* 1599 * We allow using single lower with null uuid for index and nfs_export 1600 * for example to support those features with single lower squashfs. 1601 * To avoid regressions in setups of overlay with re-formatted lower 1602 * squashfs, do not allow decoding origin with lower null uuid unless 1603 * user opted-in to one of the new features that require following the 1604 * lower inode of non-dir upper. 1605 */ 1606 if (ovl_allow_offline_changes(ofs) && uuid_is_null(uuid)) 1607 return false; 1608 1609 for (i = 0; i < ofs->numfs; i++) { 1610 /* 1611 * We use uuid to associate an overlay lower file handle with a 1612 * lower layer, so we can accept lower fs with null uuid as long 1613 * as all lower layers with null uuid are on the same fs. 1614 * if we detect multiple lower fs with the same uuid, we 1615 * disable lower file handle decoding on all of them. 1616 */ 1617 if (ofs->fs[i].is_lower && 1618 uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) { 1619 ofs->fs[i].bad_uuid = true; 1620 return false; 1621 } 1622 } 1623 return true; 1624 } 1625 1626 /* Get a unique fsid for the layer */ 1627 static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path) 1628 { 1629 struct super_block *sb = path->mnt->mnt_sb; 1630 unsigned int i; 1631 dev_t dev; 1632 int err; 1633 bool bad_uuid = false; 1634 bool warn = false; 1635 1636 for (i = 0; i < ofs->numfs; i++) { 1637 if (ofs->fs[i].sb == sb) 1638 return i; 1639 } 1640 1641 if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) { 1642 bad_uuid = true; 1643 if (ofs->config.xino == OVL_XINO_AUTO) { 1644 ofs->config.xino = OVL_XINO_OFF; 1645 warn = true; 1646 } 1647 if (ofs->config.index || ofs->config.nfs_export) { 1648 ofs->config.index = false; 1649 ofs->config.nfs_export = false; 1650 warn = true; 1651 } 1652 if (warn) { 1653 pr_warn("%s uuid detected in lower fs '%pd2', falling back to xino=%s,index=off,nfs_export=off.\n", 1654 uuid_is_null(&sb->s_uuid) ? "null" : 1655 "conflicting", 1656 path->dentry, ovl_xino_str[ofs->config.xino]); 1657 } 1658 } 1659 1660 err = get_anon_bdev(&dev); 1661 if (err) { 1662 pr_err("failed to get anonymous bdev for lowerpath\n"); 1663 return err; 1664 } 1665 1666 ofs->fs[ofs->numfs].sb = sb; 1667 ofs->fs[ofs->numfs].pseudo_dev = dev; 1668 ofs->fs[ofs->numfs].bad_uuid = bad_uuid; 1669 1670 return ofs->numfs++; 1671 } 1672 1673 static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, 1674 struct path *stack, unsigned int numlower, 1675 struct ovl_layer *layers) 1676 { 1677 int err; 1678 unsigned int i; 1679 1680 err = -ENOMEM; 1681 ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL); 1682 if (ofs->fs == NULL) 1683 goto out; 1684 1685 /* idx/fsid 0 are reserved for upper fs even with lower only overlay */ 1686 ofs->numfs++; 1687 1688 /* 1689 * All lower layers that share the same fs as upper layer, use the same 1690 * pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower 1691 * only overlay to simplify ovl_fs_free(). 1692 * is_lower will be set if upper fs is shared with a lower layer. 1693 */ 1694 err = get_anon_bdev(&ofs->fs[0].pseudo_dev); 1695 if (err) { 1696 pr_err("failed to get anonymous bdev for upper fs\n"); 1697 goto out; 1698 } 1699 1700 if (ovl_upper_mnt(ofs)) { 1701 ofs->fs[0].sb = ovl_upper_mnt(ofs)->mnt_sb; 1702 ofs->fs[0].is_lower = false; 1703 } 1704 1705 for (i = 0; i < numlower; i++) { 1706 struct vfsmount *mnt; 1707 struct inode *trap; 1708 int fsid; 1709 1710 err = fsid = ovl_get_fsid(ofs, &stack[i]); 1711 if (err < 0) 1712 goto out; 1713 1714 /* 1715 * Check if lower root conflicts with this overlay layers before 1716 * checking if it is in-use as upperdir/workdir of "another" 1717 * mount, because we do not bother to check in ovl_is_inuse() if 1718 * the upperdir/workdir is in fact in-use by our 1719 * upperdir/workdir. 1720 */ 1721 err = ovl_setup_trap(sb, stack[i].dentry, &trap, "lowerdir"); 1722 if (err) 1723 goto out; 1724 1725 if (ovl_is_inuse(stack[i].dentry)) { 1726 err = ovl_report_in_use(ofs, "lowerdir"); 1727 if (err) { 1728 iput(trap); 1729 goto out; 1730 } 1731 } 1732 1733 mnt = clone_private_mount(&stack[i]); 1734 err = PTR_ERR(mnt); 1735 if (IS_ERR(mnt)) { 1736 pr_err("failed to clone lowerpath\n"); 1737 iput(trap); 1738 goto out; 1739 } 1740 1741 /* 1742 * Make lower layers R/O. That way fchmod/fchown on lower file 1743 * will fail instead of modifying lower fs. 1744 */ 1745 mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; 1746 1747 layers[ofs->numlayer].trap = trap; 1748 layers[ofs->numlayer].mnt = mnt; 1749 layers[ofs->numlayer].idx = ofs->numlayer; 1750 layers[ofs->numlayer].fsid = fsid; 1751 layers[ofs->numlayer].fs = &ofs->fs[fsid]; 1752 ofs->numlayer++; 1753 ofs->fs[fsid].is_lower = true; 1754 } 1755 1756 /* 1757 * When all layers on same fs, overlay can use real inode numbers. 1758 * With mount option "xino=<on|auto>", mounter declares that there are 1759 * enough free high bits in underlying fs to hold the unique fsid. 1760 * If overlayfs does encounter underlying inodes using the high xino 1761 * bits reserved for fsid, it emits a warning and uses the original 1762 * inode number or a non persistent inode number allocated from a 1763 * dedicated range. 1764 */ 1765 if (ofs->numfs - !ovl_upper_mnt(ofs) == 1) { 1766 if (ofs->config.xino == OVL_XINO_ON) 1767 pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n"); 1768 ofs->xino_mode = 0; 1769 } else if (ofs->config.xino == OVL_XINO_OFF) { 1770 ofs->xino_mode = -1; 1771 } else if (ofs->xino_mode < 0) { 1772 /* 1773 * This is a roundup of number of bits needed for encoding 1774 * fsid, where fsid 0 is reserved for upper fs (even with 1775 * lower only overlay) +1 extra bit is reserved for the non 1776 * persistent inode number range that is used for resolving 1777 * xino lower bits overflow. 1778 */ 1779 BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 30); 1780 ofs->xino_mode = ilog2(ofs->numfs - 1) + 2; 1781 } 1782 1783 if (ofs->xino_mode > 0) { 1784 pr_info("\"xino\" feature enabled using %d upper inode bits.\n", 1785 ofs->xino_mode); 1786 } 1787 1788 err = 0; 1789 out: 1790 return err; 1791 } 1792 1793 static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, 1794 const char *lower, unsigned int numlower, 1795 struct ovl_fs *ofs, struct ovl_layer *layers) 1796 { 1797 int err; 1798 struct path *stack = NULL; 1799 unsigned int i; 1800 struct ovl_entry *oe; 1801 1802 if (!ofs->config.upperdir && numlower == 1) { 1803 pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n"); 1804 return ERR_PTR(-EINVAL); 1805 } 1806 1807 stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL); 1808 if (!stack) 1809 return ERR_PTR(-ENOMEM); 1810 1811 err = -EINVAL; 1812 for (i = 0; i < numlower; i++) { 1813 err = ovl_lower_dir(lower, &stack[i], ofs, &sb->s_stack_depth); 1814 if (err) 1815 goto out_err; 1816 1817 lower = strchr(lower, '\0') + 1; 1818 } 1819 1820 err = -EINVAL; 1821 sb->s_stack_depth++; 1822 if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { 1823 pr_err("maximum fs stacking depth exceeded\n"); 1824 goto out_err; 1825 } 1826 1827 err = ovl_get_layers(sb, ofs, stack, numlower, layers); 1828 if (err) 1829 goto out_err; 1830 1831 err = -ENOMEM; 1832 oe = ovl_alloc_entry(numlower); 1833 if (!oe) 1834 goto out_err; 1835 1836 for (i = 0; i < numlower; i++) { 1837 oe->lowerstack[i].dentry = dget(stack[i].dentry); 1838 oe->lowerstack[i].layer = &ofs->layers[i+1]; 1839 } 1840 1841 out: 1842 for (i = 0; i < numlower; i++) 1843 path_put(&stack[i]); 1844 kfree(stack); 1845 1846 return oe; 1847 1848 out_err: 1849 oe = ERR_PTR(err); 1850 goto out; 1851 } 1852 1853 /* 1854 * Check if this layer root is a descendant of: 1855 * - another layer of this overlayfs instance 1856 * - upper/work dir of any overlayfs instance 1857 */ 1858 static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs, 1859 struct dentry *dentry, const char *name, 1860 bool is_lower) 1861 { 1862 struct dentry *next = dentry, *parent; 1863 int err = 0; 1864 1865 if (!dentry) 1866 return 0; 1867 1868 parent = dget_parent(next); 1869 1870 /* Walk back ancestors to root (inclusive) looking for traps */ 1871 while (!err && parent != next) { 1872 if (is_lower && ovl_lookup_trap_inode(sb, parent)) { 1873 err = -ELOOP; 1874 pr_err("overlapping %s path\n", name); 1875 } else if (ovl_is_inuse(parent)) { 1876 err = ovl_report_in_use(ofs, name); 1877 } 1878 next = parent; 1879 parent = dget_parent(next); 1880 dput(next); 1881 } 1882 1883 dput(parent); 1884 1885 return err; 1886 } 1887 1888 /* 1889 * Check if any of the layers or work dirs overlap. 1890 */ 1891 static int ovl_check_overlapping_layers(struct super_block *sb, 1892 struct ovl_fs *ofs) 1893 { 1894 int i, err; 1895 1896 if (ovl_upper_mnt(ofs)) { 1897 err = ovl_check_layer(sb, ofs, ovl_upper_mnt(ofs)->mnt_root, 1898 "upperdir", false); 1899 if (err) 1900 return err; 1901 1902 /* 1903 * Checking workbasedir avoids hitting ovl_is_inuse(parent) of 1904 * this instance and covers overlapping work and index dirs, 1905 * unless work or index dir have been moved since created inside 1906 * workbasedir. In that case, we already have their traps in 1907 * inode cache and we will catch that case on lookup. 1908 */ 1909 err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir", 1910 false); 1911 if (err) 1912 return err; 1913 } 1914 1915 for (i = 1; i < ofs->numlayer; i++) { 1916 err = ovl_check_layer(sb, ofs, 1917 ofs->layers[i].mnt->mnt_root, 1918 "lowerdir", true); 1919 if (err) 1920 return err; 1921 } 1922 1923 return 0; 1924 } 1925 1926 static struct dentry *ovl_get_root(struct super_block *sb, 1927 struct dentry *upperdentry, 1928 struct ovl_entry *oe) 1929 { 1930 struct dentry *root; 1931 struct ovl_path *lowerpath = &oe->lowerstack[0]; 1932 unsigned long ino = d_inode(lowerpath->dentry)->i_ino; 1933 int fsid = lowerpath->layer->fsid; 1934 struct ovl_inode_params oip = { 1935 .upperdentry = upperdentry, 1936 .lowerpath = lowerpath, 1937 }; 1938 1939 root = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); 1940 if (!root) 1941 return NULL; 1942 1943 root->d_fsdata = oe; 1944 1945 if (upperdentry) { 1946 /* Root inode uses upper st_ino/i_ino */ 1947 ino = d_inode(upperdentry)->i_ino; 1948 fsid = 0; 1949 ovl_dentry_set_upper_alias(root); 1950 if (ovl_is_impuredir(sb, upperdentry)) 1951 ovl_set_flag(OVL_IMPURE, d_inode(root)); 1952 } 1953 1954 /* Root is always merge -> can have whiteouts */ 1955 ovl_set_flag(OVL_WHITEOUTS, d_inode(root)); 1956 ovl_dentry_set_flag(OVL_E_CONNECTED, root); 1957 ovl_set_upperdata(d_inode(root)); 1958 ovl_inode_init(d_inode(root), &oip, ino, fsid); 1959 ovl_dentry_update_reval(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE); 1960 1961 return root; 1962 } 1963 1964 static int ovl_fill_super(struct super_block *sb, void *data, int silent) 1965 { 1966 struct path upperpath = { }; 1967 struct dentry *root_dentry; 1968 struct ovl_entry *oe; 1969 struct ovl_fs *ofs; 1970 struct ovl_layer *layers; 1971 struct cred *cred; 1972 char *splitlower = NULL; 1973 unsigned int numlower; 1974 int err; 1975 1976 err = -EIO; 1977 if (WARN_ON(sb->s_user_ns != current_user_ns())) 1978 goto out; 1979 1980 sb->s_d_op = &ovl_dentry_operations; 1981 1982 err = -ENOMEM; 1983 ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); 1984 if (!ofs) 1985 goto out; 1986 1987 err = -ENOMEM; 1988 ofs->creator_cred = cred = prepare_creds(); 1989 if (!cred) 1990 goto out_err; 1991 1992 /* Is there a reason anyone would want not to share whiteouts? */ 1993 ofs->share_whiteout = true; 1994 1995 ofs->config.index = ovl_index_def; 1996 ofs->config.uuid = true; 1997 ofs->config.nfs_export = ovl_nfs_export_def; 1998 ofs->config.xino = ovl_xino_def(); 1999 ofs->config.metacopy = ovl_metacopy_def; 2000 err = ovl_parse_opt((char *) data, &ofs->config); 2001 if (err) 2002 goto out_err; 2003 2004 err = -EINVAL; 2005 if (!ofs->config.lowerdir) { 2006 if (!silent) 2007 pr_err("missing 'lowerdir'\n"); 2008 goto out_err; 2009 } 2010 2011 err = -ENOMEM; 2012 splitlower = kstrdup(ofs->config.lowerdir, GFP_KERNEL); 2013 if (!splitlower) 2014 goto out_err; 2015 2016 err = -EINVAL; 2017 numlower = ovl_split_lowerdirs(splitlower); 2018 if (numlower > OVL_MAX_STACK) { 2019 pr_err("too many lower directories, limit is %d\n", 2020 OVL_MAX_STACK); 2021 goto out_err; 2022 } 2023 2024 err = -ENOMEM; 2025 layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL); 2026 if (!layers) 2027 goto out_err; 2028 2029 ofs->layers = layers; 2030 /* Layer 0 is reserved for upper even if there's no upper */ 2031 ofs->numlayer = 1; 2032 2033 sb->s_stack_depth = 0; 2034 sb->s_maxbytes = MAX_LFS_FILESIZE; 2035 atomic_long_set(&ofs->last_ino, 1); 2036 /* Assume underlaying fs uses 32bit inodes unless proven otherwise */ 2037 if (ofs->config.xino != OVL_XINO_OFF) { 2038 ofs->xino_mode = BITS_PER_LONG - 32; 2039 if (!ofs->xino_mode) { 2040 pr_warn("xino not supported on 32bit kernel, falling back to xino=off.\n"); 2041 ofs->config.xino = OVL_XINO_OFF; 2042 } 2043 } 2044 2045 /* alloc/destroy_inode needed for setting up traps in inode cache */ 2046 sb->s_op = &ovl_super_operations; 2047 2048 if (ofs->config.upperdir) { 2049 struct super_block *upper_sb; 2050 2051 err = -EINVAL; 2052 if (!ofs->config.workdir) { 2053 pr_err("missing 'workdir'\n"); 2054 goto out_err; 2055 } 2056 2057 err = ovl_get_upper(sb, ofs, &layers[0], &upperpath); 2058 if (err) 2059 goto out_err; 2060 2061 upper_sb = ovl_upper_mnt(ofs)->mnt_sb; 2062 if (!ovl_should_sync(ofs)) { 2063 ofs->errseq = errseq_sample(&upper_sb->s_wb_err); 2064 if (errseq_check(&upper_sb->s_wb_err, ofs->errseq)) { 2065 err = -EIO; 2066 pr_err("Cannot mount volatile when upperdir has an unseen error. Sync upperdir fs to clear state.\n"); 2067 goto out_err; 2068 } 2069 } 2070 2071 err = ovl_get_workdir(sb, ofs, &upperpath); 2072 if (err) 2073 goto out_err; 2074 2075 if (!ofs->workdir) 2076 sb->s_flags |= SB_RDONLY; 2077 2078 sb->s_stack_depth = upper_sb->s_stack_depth; 2079 sb->s_time_gran = upper_sb->s_time_gran; 2080 } 2081 oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers); 2082 err = PTR_ERR(oe); 2083 if (IS_ERR(oe)) 2084 goto out_err; 2085 2086 /* If the upper fs is nonexistent, we mark overlayfs r/o too */ 2087 if (!ovl_upper_mnt(ofs)) 2088 sb->s_flags |= SB_RDONLY; 2089 2090 if (!ofs->config.uuid && ofs->numfs > 1) { 2091 pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=on.\n"); 2092 ofs->config.uuid = true; 2093 } 2094 2095 if (!ovl_force_readonly(ofs) && ofs->config.index) { 2096 err = ovl_get_indexdir(sb, ofs, oe, &upperpath); 2097 if (err) 2098 goto out_free_oe; 2099 2100 /* Force r/o mount with no index dir */ 2101 if (!ofs->indexdir) 2102 sb->s_flags |= SB_RDONLY; 2103 } 2104 2105 err = ovl_check_overlapping_layers(sb, ofs); 2106 if (err) 2107 goto out_free_oe; 2108 2109 /* Show index=off in /proc/mounts for forced r/o mount */ 2110 if (!ofs->indexdir) { 2111 ofs->config.index = false; 2112 if (ovl_upper_mnt(ofs) && ofs->config.nfs_export) { 2113 pr_warn("NFS export requires an index dir, falling back to nfs_export=off.\n"); 2114 ofs->config.nfs_export = false; 2115 } 2116 } 2117 2118 if (ofs->config.metacopy && ofs->config.nfs_export) { 2119 pr_warn("NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n"); 2120 ofs->config.nfs_export = false; 2121 } 2122 2123 if (ofs->config.nfs_export) 2124 sb->s_export_op = &ovl_export_operations; 2125 2126 /* Never override disk quota limits or use reserved space */ 2127 cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); 2128 2129 sb->s_magic = OVERLAYFS_SUPER_MAGIC; 2130 sb->s_xattr = ofs->config.userxattr ? ovl_user_xattr_handlers : 2131 ovl_trusted_xattr_handlers; 2132 sb->s_fs_info = ofs; 2133 sb->s_flags |= SB_POSIXACL; 2134 sb->s_iflags |= SB_I_SKIP_SYNC; 2135 2136 err = -ENOMEM; 2137 root_dentry = ovl_get_root(sb, upperpath.dentry, oe); 2138 if (!root_dentry) 2139 goto out_free_oe; 2140 2141 mntput(upperpath.mnt); 2142 kfree(splitlower); 2143 2144 sb->s_root = root_dentry; 2145 2146 return 0; 2147 2148 out_free_oe: 2149 ovl_entry_stack_free(oe); 2150 kfree(oe); 2151 out_err: 2152 kfree(splitlower); 2153 path_put(&upperpath); 2154 ovl_free_fs(ofs); 2155 out: 2156 return err; 2157 } 2158 2159 static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, 2160 const char *dev_name, void *raw_data) 2161 { 2162 return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); 2163 } 2164 2165 static struct file_system_type ovl_fs_type = { 2166 .owner = THIS_MODULE, 2167 .name = "overlay", 2168 .fs_flags = FS_USERNS_MOUNT, 2169 .mount = ovl_mount, 2170 .kill_sb = kill_anon_super, 2171 }; 2172 MODULE_ALIAS_FS("overlay"); 2173 2174 static void ovl_inode_init_once(void *foo) 2175 { 2176 struct ovl_inode *oi = foo; 2177 2178 inode_init_once(&oi->vfs_inode); 2179 } 2180 2181 static int __init ovl_init(void) 2182 { 2183 int err; 2184 2185 ovl_inode_cachep = kmem_cache_create("ovl_inode", 2186 sizeof(struct ovl_inode), 0, 2187 (SLAB_RECLAIM_ACCOUNT| 2188 SLAB_MEM_SPREAD|SLAB_ACCOUNT), 2189 ovl_inode_init_once); 2190 if (ovl_inode_cachep == NULL) 2191 return -ENOMEM; 2192 2193 err = ovl_aio_request_cache_init(); 2194 if (!err) { 2195 err = register_filesystem(&ovl_fs_type); 2196 if (!err) 2197 return 0; 2198 2199 ovl_aio_request_cache_destroy(); 2200 } 2201 kmem_cache_destroy(ovl_inode_cachep); 2202 2203 return err; 2204 } 2205 2206 static void __exit ovl_exit(void) 2207 { 2208 unregister_filesystem(&ovl_fs_type); 2209 2210 /* 2211 * Make sure all delayed rcu free inodes are flushed before we 2212 * destroy cache. 2213 */ 2214 rcu_barrier(); 2215 kmem_cache_destroy(ovl_inode_cachep); 2216 ovl_aio_request_cache_destroy(); 2217 } 2218 2219 module_init(ovl_init); 2220 module_exit(ovl_exit); 2221