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NFS: Remove an incorrect revalidation in nfs4_update_changeattr_locked()
[mirror_ubuntu-jammy-kernel.git] / fs / overlayfs / super.c
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 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 (mnt_user_ns(path->mnt) != &init_user_ns) {
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 path->dentry->d_sb->s_magic != SHIFTFS_MAGIC)) {
903 pr_err("filesystem on '%s' not supported as upperdir\n",
904 tmp);
905 path_put_init(path);
906 err = -EINVAL;
907 }
908 kfree(tmp);
909 }
910 return err;
911 }
912
913 static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs,
914 const char *name)
915 {
916 struct kstatfs statfs;
917 int err = vfs_statfs(path, &statfs);
918
919 if (err)
920 pr_err("statfs failed on '%s'\n", name);
921 else
922 ofs->namelen = max(ofs->namelen, statfs.f_namelen);
923
924 return err;
925 }
926
927 static int ovl_lower_dir(const char *name, struct path *path,
928 struct ovl_fs *ofs, int *stack_depth)
929 {
930 int fh_type;
931 int err;
932
933 err = ovl_mount_dir_noesc(name, path);
934 if (err)
935 return err;
936
937 err = ovl_check_namelen(path, ofs, name);
938 if (err)
939 return err;
940
941 *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
942
943 /*
944 * The inodes index feature and NFS export need to encode and decode
945 * file handles, so they require that all layers support them.
946 */
947 fh_type = ovl_can_decode_fh(path->dentry->d_sb);
948 if ((ofs->config.nfs_export ||
949 (ofs->config.index && ofs->config.upperdir)) && !fh_type) {
950 ofs->config.index = false;
951 ofs->config.nfs_export = false;
952 pr_warn("fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n",
953 name);
954 }
955 /*
956 * Decoding origin file handle is required for persistent st_ino.
957 * Without persistent st_ino, xino=auto falls back to xino=off.
958 */
959 if (ofs->config.xino == OVL_XINO_AUTO &&
960 ofs->config.upperdir && !fh_type) {
961 ofs->config.xino = OVL_XINO_OFF;
962 pr_warn("fs on '%s' does not support file handles, falling back to xino=off.\n",
963 name);
964 }
965
966 /* Check if lower fs has 32bit inode numbers */
967 if (fh_type != FILEID_INO32_GEN)
968 ofs->xino_mode = -1;
969
970 return 0;
971 }
972
973 /* Workdir should not be subdir of upperdir and vice versa */
974 static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
975 {
976 bool ok = false;
977
978 if (workdir != upperdir) {
979 ok = (lock_rename(workdir, upperdir) == NULL);
980 unlock_rename(workdir, upperdir);
981 }
982 return ok;
983 }
984
985 static unsigned int ovl_split_lowerdirs(char *str)
986 {
987 unsigned int ctr = 1;
988 char *s, *d;
989
990 for (s = d = str;; s++, d++) {
991 if (*s == '\\') {
992 s++;
993 } else if (*s == ':') {
994 *d = '\0';
995 ctr++;
996 continue;
997 }
998 *d = *s;
999 if (!*s)
1000 break;
1001 }
1002 return ctr;
1003 }
1004
1005 static int __maybe_unused
1006 ovl_posix_acl_xattr_get(const struct xattr_handler *handler,
1007 struct dentry *dentry, struct inode *inode,
1008 const char *name, void *buffer, size_t size)
1009 {
1010 return ovl_xattr_get(dentry, inode, handler->name, buffer, size);
1011 }
1012
1013 static int __maybe_unused
1014 ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
1015 struct user_namespace *mnt_userns,
1016 struct dentry *dentry, struct inode *inode,
1017 const char *name, const void *value,
1018 size_t size, int flags)
1019 {
1020 struct dentry *workdir = ovl_workdir(dentry);
1021 struct inode *realinode = ovl_inode_real(inode);
1022 struct posix_acl *acl = NULL;
1023 int err;
1024
1025 /* Check that everything is OK before copy-up */
1026 if (value) {
1027 acl = posix_acl_from_xattr(&init_user_ns, value, size);
1028 if (IS_ERR(acl))
1029 return PTR_ERR(acl);
1030 }
1031 err = -EOPNOTSUPP;
1032 if (!IS_POSIXACL(d_inode(workdir)))
1033 goto out_acl_release;
1034 if (!realinode->i_op->set_acl)
1035 goto out_acl_release;
1036 if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) {
1037 err = acl ? -EACCES : 0;
1038 goto out_acl_release;
1039 }
1040 err = -EPERM;
1041 if (!inode_owner_or_capable(&init_user_ns, inode))
1042 goto out_acl_release;
1043
1044 posix_acl_release(acl);
1045
1046 /*
1047 * Check if sgid bit needs to be cleared (actual setacl operation will
1048 * be done with mounter's capabilities and so that won't do it for us).
1049 */
1050 if (unlikely(inode->i_mode & S_ISGID) &&
1051 handler->flags == ACL_TYPE_ACCESS &&
1052 !in_group_p(inode->i_gid) &&
1053 !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID)) {
1054 struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
1055
1056 err = ovl_setattr(&init_user_ns, dentry, &iattr);
1057 if (err)
1058 return err;
1059 }
1060
1061 err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags);
1062 return err;
1063
1064 out_acl_release:
1065 posix_acl_release(acl);
1066 return err;
1067 }
1068
1069 static int ovl_own_xattr_get(const struct xattr_handler *handler,
1070 struct dentry *dentry, struct inode *inode,
1071 const char *name, void *buffer, size_t size)
1072 {
1073 return -EOPNOTSUPP;
1074 }
1075
1076 static int ovl_own_xattr_set(const struct xattr_handler *handler,
1077 struct user_namespace *mnt_userns,
1078 struct dentry *dentry, struct inode *inode,
1079 const char *name, const void *value,
1080 size_t size, int flags)
1081 {
1082 return -EOPNOTSUPP;
1083 }
1084
1085 static int ovl_other_xattr_get(const struct xattr_handler *handler,
1086 struct dentry *dentry, struct inode *inode,
1087 const char *name, void *buffer, size_t size)
1088 {
1089 return ovl_xattr_get(dentry, inode, name, buffer, size);
1090 }
1091
1092 static int ovl_other_xattr_set(const struct xattr_handler *handler,
1093 struct user_namespace *mnt_userns,
1094 struct dentry *dentry, struct inode *inode,
1095 const char *name, const void *value,
1096 size_t size, int flags)
1097 {
1098 return ovl_xattr_set(dentry, inode, name, value, size, flags);
1099 }
1100
1101 static const struct xattr_handler __maybe_unused
1102 ovl_posix_acl_access_xattr_handler = {
1103 .name = XATTR_NAME_POSIX_ACL_ACCESS,
1104 .flags = ACL_TYPE_ACCESS,
1105 .get = ovl_posix_acl_xattr_get,
1106 .set = ovl_posix_acl_xattr_set,
1107 };
1108
1109 static const struct xattr_handler __maybe_unused
1110 ovl_posix_acl_default_xattr_handler = {
1111 .name = XATTR_NAME_POSIX_ACL_DEFAULT,
1112 .flags = ACL_TYPE_DEFAULT,
1113 .get = ovl_posix_acl_xattr_get,
1114 .set = ovl_posix_acl_xattr_set,
1115 };
1116
1117 static const struct xattr_handler ovl_own_trusted_xattr_handler = {
1118 .prefix = OVL_XATTR_TRUSTED_PREFIX,
1119 .get = ovl_own_xattr_get,
1120 .set = ovl_own_xattr_set,
1121 };
1122
1123 static const struct xattr_handler ovl_own_user_xattr_handler = {
1124 .prefix = OVL_XATTR_USER_PREFIX,
1125 .get = ovl_own_xattr_get,
1126 .set = ovl_own_xattr_set,
1127 };
1128
1129 static const struct xattr_handler ovl_other_xattr_handler = {
1130 .prefix = "", /* catch all */
1131 .get = ovl_other_xattr_get,
1132 .set = ovl_other_xattr_set,
1133 };
1134
1135 static const struct xattr_handler *ovl_trusted_xattr_handlers[] = {
1136 #ifdef CONFIG_FS_POSIX_ACL
1137 &ovl_posix_acl_access_xattr_handler,
1138 &ovl_posix_acl_default_xattr_handler,
1139 #endif
1140 &ovl_own_trusted_xattr_handler,
1141 &ovl_other_xattr_handler,
1142 NULL
1143 };
1144
1145 static const struct xattr_handler *ovl_user_xattr_handlers[] = {
1146 #ifdef CONFIG_FS_POSIX_ACL
1147 &ovl_posix_acl_access_xattr_handler,
1148 &ovl_posix_acl_default_xattr_handler,
1149 #endif
1150 &ovl_own_user_xattr_handler,
1151 &ovl_other_xattr_handler,
1152 NULL
1153 };
1154
1155 static int ovl_setup_trap(struct super_block *sb, struct dentry *dir,
1156 struct inode **ptrap, const char *name)
1157 {
1158 struct inode *trap;
1159 int err;
1160
1161 trap = ovl_get_trap_inode(sb, dir);
1162 err = PTR_ERR_OR_ZERO(trap);
1163 if (err) {
1164 if (err == -ELOOP)
1165 pr_err("conflicting %s path\n", name);
1166 return err;
1167 }
1168
1169 *ptrap = trap;
1170 return 0;
1171 }
1172
1173 /*
1174 * Determine how we treat concurrent use of upperdir/workdir based on the
1175 * index feature. This is papering over mount leaks of container runtimes,
1176 * for example, an old overlay mount is leaked and now its upperdir is
1177 * attempted to be used as a lower layer in a new overlay mount.
1178 */
1179 static int ovl_report_in_use(struct ovl_fs *ofs, const char *name)
1180 {
1181 if (ofs->config.index) {
1182 pr_err("%s is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.\n",
1183 name);
1184 return -EBUSY;
1185 } else {
1186 pr_warn("%s is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.\n",
1187 name);
1188 return 0;
1189 }
1190 }
1191
1192 static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
1193 struct ovl_layer *upper_layer, struct path *upperpath)
1194 {
1195 struct vfsmount *upper_mnt;
1196 int err;
1197
1198 err = ovl_mount_dir(ofs->config.upperdir, upperpath);
1199 if (err)
1200 goto out;
1201
1202 /* Upperdir path should not be r/o */
1203 if (__mnt_is_readonly(upperpath->mnt)) {
1204 pr_err("upper fs is r/o, try multi-lower layers mount\n");
1205 err = -EINVAL;
1206 goto out;
1207 }
1208
1209 err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir);
1210 if (err)
1211 goto out;
1212
1213 err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap,
1214 "upperdir");
1215 if (err)
1216 goto out;
1217
1218 upper_mnt = clone_private_mount(upperpath);
1219 err = PTR_ERR(upper_mnt);
1220 if (IS_ERR(upper_mnt)) {
1221 pr_err("failed to clone upperpath\n");
1222 goto out;
1223 }
1224
1225 /* Don't inherit atime flags */
1226 upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
1227 upper_layer->mnt = upper_mnt;
1228 upper_layer->idx = 0;
1229 upper_layer->fsid = 0;
1230
1231 /*
1232 * Inherit SB_NOSEC flag from upperdir.
1233 *
1234 * This optimization changes behavior when a security related attribute
1235 * (suid/sgid/security.*) is changed on an underlying layer. This is
1236 * okay because we don't yet have guarantees in that case, but it will
1237 * need careful treatment once we want to honour changes to underlying
1238 * filesystems.
1239 */
1240 if (upper_mnt->mnt_sb->s_flags & SB_NOSEC)
1241 sb->s_flags |= SB_NOSEC;
1242
1243 if (ovl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root)) {
1244 ofs->upperdir_locked = true;
1245 } else {
1246 err = ovl_report_in_use(ofs, "upperdir");
1247 if (err)
1248 goto out;
1249 }
1250
1251 err = 0;
1252 out:
1253 return err;
1254 }
1255
1256 /*
1257 * Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and
1258 * negative values if error is encountered.
1259 */
1260 static int ovl_check_rename_whiteout(struct dentry *workdir)
1261 {
1262 struct inode *dir = d_inode(workdir);
1263 struct dentry *temp;
1264 struct dentry *dest;
1265 struct dentry *whiteout;
1266 struct name_snapshot name;
1267 int err;
1268
1269 inode_lock_nested(dir, I_MUTEX_PARENT);
1270
1271 temp = ovl_create_temp(workdir, OVL_CATTR(S_IFREG | 0));
1272 err = PTR_ERR(temp);
1273 if (IS_ERR(temp))
1274 goto out_unlock;
1275
1276 dest = ovl_lookup_temp(workdir);
1277 err = PTR_ERR(dest);
1278 if (IS_ERR(dest)) {
1279 dput(temp);
1280 goto out_unlock;
1281 }
1282
1283 /* Name is inline and stable - using snapshot as a copy helper */
1284 take_dentry_name_snapshot(&name, temp);
1285 err = ovl_do_rename(dir, temp, dir, dest, RENAME_WHITEOUT);
1286 if (err) {
1287 if (err == -EINVAL)
1288 err = 0;
1289 goto cleanup_temp;
1290 }
1291
1292 whiteout = lookup_one_len(name.name.name, workdir, name.name.len);
1293 err = PTR_ERR(whiteout);
1294 if (IS_ERR(whiteout))
1295 goto cleanup_temp;
1296
1297 err = ovl_is_whiteout(whiteout);
1298
1299 /* Best effort cleanup of whiteout and temp file */
1300 if (err)
1301 ovl_cleanup(dir, whiteout);
1302 dput(whiteout);
1303
1304 cleanup_temp:
1305 ovl_cleanup(dir, temp);
1306 release_dentry_name_snapshot(&name);
1307 dput(temp);
1308 dput(dest);
1309
1310 out_unlock:
1311 inode_unlock(dir);
1312
1313 return err;
1314 }
1315
1316 static struct dentry *ovl_lookup_or_create(struct dentry *parent,
1317 const char *name, umode_t mode)
1318 {
1319 size_t len = strlen(name);
1320 struct dentry *child;
1321
1322 inode_lock_nested(parent->d_inode, I_MUTEX_PARENT);
1323 child = lookup_one_len(name, parent, len);
1324 if (!IS_ERR(child) && !child->d_inode)
1325 child = ovl_create_real(parent->d_inode, child,
1326 OVL_CATTR(mode));
1327 inode_unlock(parent->d_inode);
1328 dput(parent);
1329
1330 return child;
1331 }
1332
1333 /*
1334 * Creates $workdir/work/incompat/volatile/dirty file if it is not already
1335 * present.
1336 */
1337 static int ovl_create_volatile_dirty(struct ovl_fs *ofs)
1338 {
1339 unsigned int ctr;
1340 struct dentry *d = dget(ofs->workbasedir);
1341 static const char *const volatile_path[] = {
1342 OVL_WORKDIR_NAME, "incompat", "volatile", "dirty"
1343 };
1344 const char *const *name = volatile_path;
1345
1346 for (ctr = ARRAY_SIZE(volatile_path); ctr; ctr--, name++) {
1347 d = ovl_lookup_or_create(d, *name, ctr > 1 ? S_IFDIR : S_IFREG);
1348 if (IS_ERR(d))
1349 return PTR_ERR(d);
1350 }
1351 dput(d);
1352 return 0;
1353 }
1354
1355 static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
1356 struct path *workpath)
1357 {
1358 struct vfsmount *mnt = ovl_upper_mnt(ofs);
1359 struct dentry *temp, *workdir;
1360 bool rename_whiteout;
1361 bool d_type;
1362 int fh_type;
1363 int err;
1364
1365 err = mnt_want_write(mnt);
1366 if (err)
1367 return err;
1368
1369 workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false);
1370 err = PTR_ERR(workdir);
1371 if (IS_ERR_OR_NULL(workdir))
1372 goto out;
1373
1374 ofs->workdir = workdir;
1375
1376 err = ovl_setup_trap(sb, ofs->workdir, &ofs->workdir_trap, "workdir");
1377 if (err)
1378 goto out;
1379
1380 /*
1381 * Upper should support d_type, else whiteouts are visible. Given
1382 * workdir and upper are on same fs, we can do iterate_dir() on
1383 * workdir. This check requires successful creation of workdir in
1384 * previous step.
1385 */
1386 err = ovl_check_d_type_supported(workpath);
1387 if (err < 0)
1388 goto out;
1389
1390 d_type = err;
1391 if (!d_type)
1392 pr_warn("upper fs needs to support d_type.\n");
1393
1394 /* Check if upper/work fs supports O_TMPFILE */
1395 temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0);
1396 ofs->tmpfile = !IS_ERR(temp);
1397 if (ofs->tmpfile)
1398 dput(temp);
1399 else
1400 pr_warn("upper fs does not support tmpfile.\n");
1401
1402
1403 /* Check if upper/work fs supports RENAME_WHITEOUT */
1404 err = ovl_check_rename_whiteout(ofs->workdir);
1405 if (err < 0)
1406 goto out;
1407
1408 rename_whiteout = err;
1409 if (!rename_whiteout)
1410 pr_warn("upper fs does not support RENAME_WHITEOUT.\n");
1411
1412 /*
1413 * Check if upper/work fs supports (trusted|user).overlay.* xattr
1414 */
1415 err = ovl_do_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1);
1416 if (err) {
1417 ofs->noxattr = true;
1418 if (ofs->config.index || ofs->config.metacopy) {
1419 ofs->config.index = false;
1420 ofs->config.metacopy = false;
1421 pr_warn("upper fs does not support xattr, falling back to index=off,metacopy=off.\n");
1422 }
1423 /*
1424 * xattr support is required for persistent st_ino.
1425 * Without persistent st_ino, xino=auto falls back to xino=off.
1426 */
1427 if (ofs->config.xino == OVL_XINO_AUTO) {
1428 ofs->config.xino = OVL_XINO_OFF;
1429 pr_warn("upper fs does not support xattr, falling back to xino=off.\n");
1430 }
1431 err = 0;
1432 } else {
1433 ovl_do_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE);
1434 }
1435
1436 /*
1437 * We allowed sub-optimal upper fs configuration and don't want to break
1438 * users over kernel upgrade, but we never allowed remote upper fs, so
1439 * we can enforce strict requirements for remote upper fs.
1440 */
1441 if (ovl_dentry_remote(ofs->workdir) &&
1442 (!d_type || !rename_whiteout || ofs->noxattr)) {
1443 pr_err("upper fs missing required features.\n");
1444 err = -EINVAL;
1445 goto out;
1446 }
1447
1448 /*
1449 * For volatile mount, create a incompat/volatile/dirty file to keep
1450 * track of it.
1451 */
1452 if (ofs->config.ovl_volatile) {
1453 err = ovl_create_volatile_dirty(ofs);
1454 if (err < 0) {
1455 pr_err("Failed to create volatile/dirty file.\n");
1456 goto out;
1457 }
1458 }
1459
1460 /* Check if upper/work fs supports file handles */
1461 fh_type = ovl_can_decode_fh(ofs->workdir->d_sb);
1462 if (ofs->config.index && !fh_type) {
1463 ofs->config.index = false;
1464 pr_warn("upper fs does not support file handles, falling back to index=off.\n");
1465 }
1466
1467 /* Check if upper fs has 32bit inode numbers */
1468 if (fh_type != FILEID_INO32_GEN)
1469 ofs->xino_mode = -1;
1470
1471 /* NFS export of r/w mount depends on index */
1472 if (ofs->config.nfs_export && !ofs->config.index) {
1473 pr_warn("NFS export requires \"index=on\", falling back to nfs_export=off.\n");
1474 ofs->config.nfs_export = false;
1475 }
1476 out:
1477 mnt_drop_write(mnt);
1478 return err;
1479 }
1480
1481 static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs,
1482 struct path *upperpath)
1483 {
1484 int err;
1485 struct path workpath = { };
1486
1487 err = ovl_mount_dir(ofs->config.workdir, &workpath);
1488 if (err)
1489 goto out;
1490
1491 err = -EINVAL;
1492 if (upperpath->mnt != workpath.mnt) {
1493 pr_err("workdir and upperdir must reside under the same mount\n");
1494 goto out;
1495 }
1496 if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) {
1497 pr_err("workdir and upperdir must be separate subtrees\n");
1498 goto out;
1499 }
1500
1501 ofs->workbasedir = dget(workpath.dentry);
1502
1503 if (ovl_inuse_trylock(ofs->workbasedir)) {
1504 ofs->workdir_locked = true;
1505 } else {
1506 err = ovl_report_in_use(ofs, "workdir");
1507 if (err)
1508 goto out;
1509 }
1510
1511 err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap,
1512 "workdir");
1513 if (err)
1514 goto out;
1515
1516 err = ovl_make_workdir(sb, ofs, &workpath);
1517
1518 out:
1519 path_put(&workpath);
1520
1521 return err;
1522 }
1523
1524 static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs,
1525 struct ovl_entry *oe, struct path *upperpath)
1526 {
1527 struct vfsmount *mnt = ovl_upper_mnt(ofs);
1528 struct dentry *indexdir;
1529 int err;
1530
1531 err = mnt_want_write(mnt);
1532 if (err)
1533 return err;
1534
1535 /* Verify lower root is upper root origin */
1536 err = ovl_verify_origin(ofs, upperpath->dentry,
1537 oe->lowerstack[0].dentry, true);
1538 if (err) {
1539 pr_err("failed to verify upper root origin\n");
1540 goto out;
1541 }
1542
1543 /* index dir will act also as workdir */
1544 iput(ofs->workdir_trap);
1545 ofs->workdir_trap = NULL;
1546 dput(ofs->workdir);
1547 ofs->workdir = NULL;
1548 indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true);
1549 if (IS_ERR(indexdir)) {
1550 err = PTR_ERR(indexdir);
1551 } else if (indexdir) {
1552 ofs->indexdir = indexdir;
1553 ofs->workdir = dget(indexdir);
1554
1555 err = ovl_setup_trap(sb, ofs->indexdir, &ofs->indexdir_trap,
1556 "indexdir");
1557 if (err)
1558 goto out;
1559
1560 /*
1561 * Verify upper root is exclusively associated with index dir.
1562 * Older kernels stored upper fh in ".overlay.origin"
1563 * xattr. If that xattr exists, verify that it is a match to
1564 * upper dir file handle. In any case, verify or set xattr
1565 * ".overlay.upper" to indicate that index may have
1566 * directory entries.
1567 */
1568 if (ovl_check_origin_xattr(ofs, ofs->indexdir)) {
1569 err = ovl_verify_set_fh(ofs, ofs->indexdir,
1570 OVL_XATTR_ORIGIN,
1571 upperpath->dentry, true, false);
1572 if (err)
1573 pr_err("failed to verify index dir 'origin' xattr\n");
1574 }
1575 err = ovl_verify_upper(ofs, ofs->indexdir, upperpath->dentry,
1576 true);
1577 if (err)
1578 pr_err("failed to verify index dir 'upper' xattr\n");
1579
1580 /* Cleanup bad/stale/orphan index entries */
1581 if (!err)
1582 err = ovl_indexdir_cleanup(ofs);
1583 }
1584 if (err || !ofs->indexdir)
1585 pr_warn("try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
1586
1587 out:
1588 mnt_drop_write(mnt);
1589 return err;
1590 }
1591
1592 static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid)
1593 {
1594 unsigned int i;
1595
1596 if (!ofs->config.nfs_export && !ovl_upper_mnt(ofs))
1597 return true;
1598
1599 /*
1600 * We allow using single lower with null uuid for index and nfs_export
1601 * for example to support those features with single lower squashfs.
1602 * To avoid regressions in setups of overlay with re-formatted lower
1603 * squashfs, do not allow decoding origin with lower null uuid unless
1604 * user opted-in to one of the new features that require following the
1605 * lower inode of non-dir upper.
1606 */
1607 if (ovl_allow_offline_changes(ofs) && uuid_is_null(uuid))
1608 return false;
1609
1610 for (i = 0; i < ofs->numfs; i++) {
1611 /*
1612 * We use uuid to associate an overlay lower file handle with a
1613 * lower layer, so we can accept lower fs with null uuid as long
1614 * as all lower layers with null uuid are on the same fs.
1615 * if we detect multiple lower fs with the same uuid, we
1616 * disable lower file handle decoding on all of them.
1617 */
1618 if (ofs->fs[i].is_lower &&
1619 uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) {
1620 ofs->fs[i].bad_uuid = true;
1621 return false;
1622 }
1623 }
1624 return true;
1625 }
1626
1627 /* Get a unique fsid for the layer */
1628 static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path)
1629 {
1630 struct super_block *sb = path->mnt->mnt_sb;
1631 unsigned int i;
1632 dev_t dev;
1633 int err;
1634 bool bad_uuid = false;
1635 bool warn = false;
1636
1637 for (i = 0; i < ofs->numfs; i++) {
1638 if (ofs->fs[i].sb == sb)
1639 return i;
1640 }
1641
1642 if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) {
1643 bad_uuid = true;
1644 if (ofs->config.xino == OVL_XINO_AUTO) {
1645 ofs->config.xino = OVL_XINO_OFF;
1646 warn = true;
1647 }
1648 if (ofs->config.index || ofs->config.nfs_export) {
1649 ofs->config.index = false;
1650 ofs->config.nfs_export = false;
1651 warn = true;
1652 }
1653 if (warn) {
1654 pr_warn("%s uuid detected in lower fs '%pd2', falling back to xino=%s,index=off,nfs_export=off.\n",
1655 uuid_is_null(&sb->s_uuid) ? "null" :
1656 "conflicting",
1657 path->dentry, ovl_xino_str[ofs->config.xino]);
1658 }
1659 }
1660
1661 err = get_anon_bdev(&dev);
1662 if (err) {
1663 pr_err("failed to get anonymous bdev for lowerpath\n");
1664 return err;
1665 }
1666
1667 ofs->fs[ofs->numfs].sb = sb;
1668 ofs->fs[ofs->numfs].pseudo_dev = dev;
1669 ofs->fs[ofs->numfs].bad_uuid = bad_uuid;
1670
1671 return ofs->numfs++;
1672 }
1673
1674 static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
1675 struct path *stack, unsigned int numlower,
1676 struct ovl_layer *layers)
1677 {
1678 int err;
1679 unsigned int i;
1680
1681 err = -ENOMEM;
1682 ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL);
1683 if (ofs->fs == NULL)
1684 goto out;
1685
1686 /* idx/fsid 0 are reserved for upper fs even with lower only overlay */
1687 ofs->numfs++;
1688
1689 /*
1690 * All lower layers that share the same fs as upper layer, use the same
1691 * pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower
1692 * only overlay to simplify ovl_fs_free().
1693 * is_lower will be set if upper fs is shared with a lower layer.
1694 */
1695 err = get_anon_bdev(&ofs->fs[0].pseudo_dev);
1696 if (err) {
1697 pr_err("failed to get anonymous bdev for upper fs\n");
1698 goto out;
1699 }
1700
1701 if (ovl_upper_mnt(ofs)) {
1702 ofs->fs[0].sb = ovl_upper_mnt(ofs)->mnt_sb;
1703 ofs->fs[0].is_lower = false;
1704 }
1705
1706 for (i = 0; i < numlower; i++) {
1707 struct vfsmount *mnt;
1708 struct inode *trap;
1709 int fsid;
1710
1711 err = fsid = ovl_get_fsid(ofs, &stack[i]);
1712 if (err < 0)
1713 goto out;
1714
1715 /*
1716 * Check if lower root conflicts with this overlay layers before
1717 * checking if it is in-use as upperdir/workdir of "another"
1718 * mount, because we do not bother to check in ovl_is_inuse() if
1719 * the upperdir/workdir is in fact in-use by our
1720 * upperdir/workdir.
1721 */
1722 err = ovl_setup_trap(sb, stack[i].dentry, &trap, "lowerdir");
1723 if (err)
1724 goto out;
1725
1726 if (ovl_is_inuse(stack[i].dentry)) {
1727 err = ovl_report_in_use(ofs, "lowerdir");
1728 if (err) {
1729 iput(trap);
1730 goto out;
1731 }
1732 }
1733
1734 mnt = clone_private_mount(&stack[i]);
1735 err = PTR_ERR(mnt);
1736 if (IS_ERR(mnt)) {
1737 pr_err("failed to clone lowerpath\n");
1738 iput(trap);
1739 goto out;
1740 }
1741
1742 /*
1743 * Make lower layers R/O. That way fchmod/fchown on lower file
1744 * will fail instead of modifying lower fs.
1745 */
1746 mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
1747
1748 layers[ofs->numlayer].trap = trap;
1749 layers[ofs->numlayer].mnt = mnt;
1750 layers[ofs->numlayer].idx = ofs->numlayer;
1751 layers[ofs->numlayer].fsid = fsid;
1752 layers[ofs->numlayer].fs = &ofs->fs[fsid];
1753 ofs->numlayer++;
1754 ofs->fs[fsid].is_lower = true;
1755 }
1756
1757 /*
1758 * When all layers on same fs, overlay can use real inode numbers.
1759 * With mount option "xino=<on|auto>", mounter declares that there are
1760 * enough free high bits in underlying fs to hold the unique fsid.
1761 * If overlayfs does encounter underlying inodes using the high xino
1762 * bits reserved for fsid, it emits a warning and uses the original
1763 * inode number or a non persistent inode number allocated from a
1764 * dedicated range.
1765 */
1766 if (ofs->numfs - !ovl_upper_mnt(ofs) == 1) {
1767 if (ofs->config.xino == OVL_XINO_ON)
1768 pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n");
1769 ofs->xino_mode = 0;
1770 } else if (ofs->config.xino == OVL_XINO_OFF) {
1771 ofs->xino_mode = -1;
1772 } else if (ofs->xino_mode < 0) {
1773 /*
1774 * This is a roundup of number of bits needed for encoding
1775 * fsid, where fsid 0 is reserved for upper fs (even with
1776 * lower only overlay) +1 extra bit is reserved for the non
1777 * persistent inode number range that is used for resolving
1778 * xino lower bits overflow.
1779 */
1780 BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 30);
1781 ofs->xino_mode = ilog2(ofs->numfs - 1) + 2;
1782 }
1783
1784 if (ofs->xino_mode > 0) {
1785 pr_info("\"xino\" feature enabled using %d upper inode bits.\n",
1786 ofs->xino_mode);
1787 }
1788
1789 err = 0;
1790 out:
1791 return err;
1792 }
1793
1794 static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
1795 const char *lower, unsigned int numlower,
1796 struct ovl_fs *ofs, struct ovl_layer *layers)
1797 {
1798 int err;
1799 struct path *stack = NULL;
1800 unsigned int i;
1801 struct ovl_entry *oe;
1802
1803 if (!ofs->config.upperdir && numlower == 1) {
1804 pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n");
1805 return ERR_PTR(-EINVAL);
1806 }
1807
1808 stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL);
1809 if (!stack)
1810 return ERR_PTR(-ENOMEM);
1811
1812 err = -EINVAL;
1813 for (i = 0; i < numlower; i++) {
1814 err = ovl_lower_dir(lower, &stack[i], ofs, &sb->s_stack_depth);
1815 if (err)
1816 goto out_err;
1817
1818 lower = strchr(lower, '\0') + 1;
1819 }
1820
1821 err = -EINVAL;
1822 sb->s_stack_depth++;
1823 if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
1824 pr_err("maximum fs stacking depth exceeded\n");
1825 goto out_err;
1826 }
1827
1828 err = ovl_get_layers(sb, ofs, stack, numlower, layers);
1829 if (err)
1830 goto out_err;
1831
1832 err = -ENOMEM;
1833 oe = ovl_alloc_entry(numlower);
1834 if (!oe)
1835 goto out_err;
1836
1837 for (i = 0; i < numlower; i++) {
1838 oe->lowerstack[i].dentry = dget(stack[i].dentry);
1839 oe->lowerstack[i].layer = &ofs->layers[i+1];
1840 }
1841
1842 out:
1843 for (i = 0; i < numlower; i++)
1844 path_put(&stack[i]);
1845 kfree(stack);
1846
1847 return oe;
1848
1849 out_err:
1850 oe = ERR_PTR(err);
1851 goto out;
1852 }
1853
1854 /*
1855 * Check if this layer root is a descendant of:
1856 * - another layer of this overlayfs instance
1857 * - upper/work dir of any overlayfs instance
1858 */
1859 static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs,
1860 struct dentry *dentry, const char *name,
1861 bool is_lower)
1862 {
1863 struct dentry *next = dentry, *parent;
1864 int err = 0;
1865
1866 if (!dentry)
1867 return 0;
1868
1869 parent = dget_parent(next);
1870
1871 /* Walk back ancestors to root (inclusive) looking for traps */
1872 while (!err && parent != next) {
1873 if (is_lower && ovl_lookup_trap_inode(sb, parent)) {
1874 err = -ELOOP;
1875 pr_err("overlapping %s path\n", name);
1876 } else if (ovl_is_inuse(parent)) {
1877 err = ovl_report_in_use(ofs, name);
1878 }
1879 next = parent;
1880 parent = dget_parent(next);
1881 dput(next);
1882 }
1883
1884 dput(parent);
1885
1886 return err;
1887 }
1888
1889 /*
1890 * Check if any of the layers or work dirs overlap.
1891 */
1892 static int ovl_check_overlapping_layers(struct super_block *sb,
1893 struct ovl_fs *ofs)
1894 {
1895 int i, err;
1896
1897 if (ovl_upper_mnt(ofs)) {
1898 err = ovl_check_layer(sb, ofs, ovl_upper_mnt(ofs)->mnt_root,
1899 "upperdir", false);
1900 if (err)
1901 return err;
1902
1903 /*
1904 * Checking workbasedir avoids hitting ovl_is_inuse(parent) of
1905 * this instance and covers overlapping work and index dirs,
1906 * unless work or index dir have been moved since created inside
1907 * workbasedir. In that case, we already have their traps in
1908 * inode cache and we will catch that case on lookup.
1909 */
1910 err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir",
1911 false);
1912 if (err)
1913 return err;
1914 }
1915
1916 for (i = 1; i < ofs->numlayer; i++) {
1917 err = ovl_check_layer(sb, ofs,
1918 ofs->layers[i].mnt->mnt_root,
1919 "lowerdir", true);
1920 if (err)
1921 return err;
1922 }
1923
1924 return 0;
1925 }
1926
1927 static struct dentry *ovl_get_root(struct super_block *sb,
1928 struct dentry *upperdentry,
1929 struct ovl_entry *oe)
1930 {
1931 struct dentry *root;
1932 struct ovl_path *lowerpath = &oe->lowerstack[0];
1933 unsigned long ino = d_inode(lowerpath->dentry)->i_ino;
1934 int fsid = lowerpath->layer->fsid;
1935 struct ovl_inode_params oip = {
1936 .upperdentry = upperdentry,
1937 .lowerpath = lowerpath,
1938 };
1939
1940 root = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
1941 if (!root)
1942 return NULL;
1943
1944 root->d_fsdata = oe;
1945
1946 if (upperdentry) {
1947 /* Root inode uses upper st_ino/i_ino */
1948 ino = d_inode(upperdentry)->i_ino;
1949 fsid = 0;
1950 ovl_dentry_set_upper_alias(root);
1951 if (ovl_is_impuredir(sb, upperdentry))
1952 ovl_set_flag(OVL_IMPURE, d_inode(root));
1953 }
1954
1955 /* Root is always merge -> can have whiteouts */
1956 ovl_set_flag(OVL_WHITEOUTS, d_inode(root));
1957 ovl_dentry_set_flag(OVL_E_CONNECTED, root);
1958 ovl_set_upperdata(d_inode(root));
1959 ovl_inode_init(d_inode(root), &oip, ino, fsid);
1960 ovl_dentry_update_reval(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE);
1961
1962 return root;
1963 }
1964
1965 static int ovl_fill_super(struct super_block *sb, void *data, int silent)
1966 {
1967 struct path upperpath = { };
1968 struct dentry *root_dentry;
1969 struct ovl_entry *oe;
1970 struct ovl_fs *ofs;
1971 struct ovl_layer *layers;
1972 struct cred *cred;
1973 char *splitlower = NULL;
1974 unsigned int numlower;
1975 int err;
1976
1977 err = -EIO;
1978 if (WARN_ON(sb->s_user_ns != current_user_ns()))
1979 goto out;
1980
1981 sb->s_d_op = &ovl_dentry_operations;
1982
1983 err = -ENOMEM;
1984 ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
1985 if (!ofs)
1986 goto out;
1987
1988 err = -ENOMEM;
1989 ofs->creator_cred = cred = prepare_creds();
1990 if (!cred)
1991 goto out_err;
1992
1993 /* Is there a reason anyone would want not to share whiteouts? */
1994 ofs->share_whiteout = true;
1995
1996 ofs->config.index = ovl_index_def;
1997 ofs->config.uuid = true;
1998 ofs->config.nfs_export = ovl_nfs_export_def;
1999 ofs->config.xino = ovl_xino_def();
2000 ofs->config.metacopy = ovl_metacopy_def;
2001 err = ovl_parse_opt((char *) data, &ofs->config);
2002 if (err)
2003 goto out_err;
2004
2005 err = -EINVAL;
2006 if (!ofs->config.lowerdir) {
2007 if (!silent)
2008 pr_err("missing 'lowerdir'\n");
2009 goto out_err;
2010 }
2011
2012 err = -ENOMEM;
2013 splitlower = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
2014 if (!splitlower)
2015 goto out_err;
2016
2017 err = -EINVAL;
2018 numlower = ovl_split_lowerdirs(splitlower);
2019 if (numlower > OVL_MAX_STACK) {
2020 pr_err("too many lower directories, limit is %d\n",
2021 OVL_MAX_STACK);
2022 goto out_err;
2023 }
2024
2025 err = -ENOMEM;
2026 layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL);
2027 if (!layers)
2028 goto out_err;
2029
2030 ofs->layers = layers;
2031 /* Layer 0 is reserved for upper even if there's no upper */
2032 ofs->numlayer = 1;
2033
2034 sb->s_stack_depth = 0;
2035 sb->s_maxbytes = MAX_LFS_FILESIZE;
2036 atomic_long_set(&ofs->last_ino, 1);
2037 /* Assume underlaying fs uses 32bit inodes unless proven otherwise */
2038 if (ofs->config.xino != OVL_XINO_OFF) {
2039 ofs->xino_mode = BITS_PER_LONG - 32;
2040 if (!ofs->xino_mode) {
2041 pr_warn("xino not supported on 32bit kernel, falling back to xino=off.\n");
2042 ofs->config.xino = OVL_XINO_OFF;
2043 }
2044 }
2045
2046 /* alloc/destroy_inode needed for setting up traps in inode cache */
2047 sb->s_op = &ovl_super_operations;
2048
2049 if (ofs->config.upperdir) {
2050 struct super_block *upper_sb;
2051
2052 err = -EINVAL;
2053 if (!ofs->config.workdir) {
2054 pr_err("missing 'workdir'\n");
2055 goto out_err;
2056 }
2057
2058 err = ovl_get_upper(sb, ofs, &layers[0], &upperpath);
2059 if (err)
2060 goto out_err;
2061
2062 upper_sb = ovl_upper_mnt(ofs)->mnt_sb;
2063 if (!ovl_should_sync(ofs)) {
2064 ofs->errseq = errseq_sample(&upper_sb->s_wb_err);
2065 if (errseq_check(&upper_sb->s_wb_err, ofs->errseq)) {
2066 err = -EIO;
2067 pr_err("Cannot mount volatile when upperdir has an unseen error. Sync upperdir fs to clear state.\n");
2068 goto out_err;
2069 }
2070 }
2071
2072 err = ovl_get_workdir(sb, ofs, &upperpath);
2073 if (err)
2074 goto out_err;
2075
2076 if (!ofs->workdir)
2077 sb->s_flags |= SB_RDONLY;
2078
2079 sb->s_stack_depth = upper_sb->s_stack_depth;
2080 sb->s_time_gran = upper_sb->s_time_gran;
2081 }
2082 oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers);
2083 err = PTR_ERR(oe);
2084 if (IS_ERR(oe))
2085 goto out_err;
2086
2087 /* If the upper fs is nonexistent, we mark overlayfs r/o too */
2088 if (!ovl_upper_mnt(ofs))
2089 sb->s_flags |= SB_RDONLY;
2090
2091 if (!ofs->config.uuid && ofs->numfs > 1) {
2092 pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=on.\n");
2093 ofs->config.uuid = true;
2094 }
2095
2096 if (!ovl_force_readonly(ofs) && ofs->config.index) {
2097 err = ovl_get_indexdir(sb, ofs, oe, &upperpath);
2098 if (err)
2099 goto out_free_oe;
2100
2101 /* Force r/o mount with no index dir */
2102 if (!ofs->indexdir)
2103 sb->s_flags |= SB_RDONLY;
2104 }
2105
2106 err = ovl_check_overlapping_layers(sb, ofs);
2107 if (err)
2108 goto out_free_oe;
2109
2110 /* Show index=off in /proc/mounts for forced r/o mount */
2111 if (!ofs->indexdir) {
2112 ofs->config.index = false;
2113 if (ovl_upper_mnt(ofs) && ofs->config.nfs_export) {
2114 pr_warn("NFS export requires an index dir, falling back to nfs_export=off.\n");
2115 ofs->config.nfs_export = false;
2116 }
2117 }
2118
2119 if (ofs->config.metacopy && ofs->config.nfs_export) {
2120 pr_warn("NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n");
2121 ofs->config.nfs_export = false;
2122 }
2123
2124 if (ofs->config.nfs_export)
2125 sb->s_export_op = &ovl_export_operations;
2126
2127 /* Never override disk quota limits or use reserved space */
2128 cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);
2129
2130 sb->s_magic = OVERLAYFS_SUPER_MAGIC;
2131 sb->s_xattr = ofs->config.userxattr ? ovl_user_xattr_handlers :
2132 ovl_trusted_xattr_handlers;
2133 sb->s_fs_info = ofs;
2134 sb->s_flags |= SB_POSIXACL;
2135 sb->s_iflags |= SB_I_SKIP_SYNC;
2136
2137 err = -ENOMEM;
2138 root_dentry = ovl_get_root(sb, upperpath.dentry, oe);
2139 if (!root_dentry)
2140 goto out_free_oe;
2141
2142 mntput(upperpath.mnt);
2143 kfree(splitlower);
2144
2145 sb->s_root = root_dentry;
2146
2147 return 0;
2148
2149 out_free_oe:
2150 ovl_entry_stack_free(oe);
2151 kfree(oe);
2152 out_err:
2153 kfree(splitlower);
2154 path_put(&upperpath);
2155 ovl_free_fs(ofs);
2156 out:
2157 return err;
2158 }
2159
2160 static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
2161 const char *dev_name, void *raw_data)
2162 {
2163 return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
2164 }
2165
2166 static struct file_system_type ovl_fs_type = {
2167 .owner = THIS_MODULE,
2168 .name = "overlay",
2169 .fs_flags = FS_USERNS_MOUNT,
2170 .mount = ovl_mount,
2171 .kill_sb = kill_anon_super,
2172 };
2173 MODULE_ALIAS_FS("overlay");
2174
2175 static void ovl_inode_init_once(void *foo)
2176 {
2177 struct ovl_inode *oi = foo;
2178
2179 inode_init_once(&oi->vfs_inode);
2180 }
2181
2182 static int __init ovl_init(void)
2183 {
2184 int err;
2185
2186 ovl_inode_cachep = kmem_cache_create("ovl_inode",
2187 sizeof(struct ovl_inode), 0,
2188 (SLAB_RECLAIM_ACCOUNT|
2189 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
2190 ovl_inode_init_once);
2191 if (ovl_inode_cachep == NULL)
2192 return -ENOMEM;
2193
2194 err = ovl_aio_request_cache_init();
2195 if (!err) {
2196 err = register_filesystem(&ovl_fs_type);
2197 if (!err)
2198 return 0;
2199
2200 ovl_aio_request_cache_destroy();
2201 }
2202 kmem_cache_destroy(ovl_inode_cachep);
2203
2204 return err;
2205 }
2206
2207 static void __exit ovl_exit(void)
2208 {
2209 unregister_filesystem(&ovl_fs_type);
2210
2211 /*
2212 * Make sure all delayed rcu free inodes are flushed before we
2213 * destroy cache.
2214 */
2215 rcu_barrier();
2216 kmem_cache_destroy(ovl_inode_cachep);
2217 ovl_aio_request_cache_destroy();
2218 }
2219
2220 module_init(ovl_init);
2221 module_exit(ovl_exit);
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