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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
20MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
21MODULE_DESCRIPTION("Overlay filesystem");
22MODULE_LICENSE("GPL");
23
24
25struct ovl_dir_cache;
26
27#define OVL_MAX_STACK 500
28
29static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR);
30module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644);
31MODULE_PARM_DESC(redirect_dir,
32 "Default to on or off for the redirect_dir feature");
33
34static bool ovl_redirect_always_follow =
35 IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW);
36module_param_named(redirect_always_follow, ovl_redirect_always_follow,
37 bool, 0644);
38MODULE_PARM_DESC(redirect_always_follow,
39 "Follow redirects even if redirect_dir feature is turned off");
40
41static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX);
42module_param_named(index, ovl_index_def, bool, 0644);
43MODULE_PARM_DESC(index,
44 "Default to on or off for the inodes index feature");
45
46static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT);
47module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644);
48MODULE_PARM_DESC(nfs_export,
49 "Default to on or off for the NFS export feature");
50
51static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO);
52module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644);
53MODULE_PARM_DESC(xino_auto,
54 "Auto enable xino feature");
55
56static 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
64static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY);
65module_param_named(metacopy, ovl_metacopy_def, bool, 0644);
66MODULE_PARM_DESC(metacopy,
67 "Default to on or off for the metadata only copy up feature");
68
69static 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
79static struct dentry *ovl_d_real(struct dentry *dentry,
80 const struct inode *inode)
81{
82 struct dentry *real;
83
84
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 real = ovl_dentry_lowerdata(dentry);
102 if (!real)
103 goto bug;
104
105
106 real = d_real(real, inode);
107
108 if (!inode || inode == d_inode(real))
109 return real;
110bug:
111 WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry,
112 inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0);
113 return dentry;
114}
115
116static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
117{
118 struct ovl_entry *oe = dentry->d_fsdata;
119 unsigned int i;
120 int ret = 1;
121
122 for (i = 0; i < oe->numlower; i++) {
123 struct dentry *d = oe->lowerstack[i].dentry;
124
125 if (d->d_flags & DCACHE_OP_REVALIDATE) {
126 ret = d->d_op->d_revalidate(d, flags);
127 if (ret < 0)
128 return ret;
129 if (!ret) {
130 if (!(flags & LOOKUP_RCU))
131 d_invalidate(d);
132 return -ESTALE;
133 }
134 }
135 }
136 return 1;
137}
138
139static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
140{
141 struct ovl_entry *oe = dentry->d_fsdata;
142 unsigned int i;
143 int ret = 1;
144
145 for (i = 0; i < oe->numlower; i++) {
146 struct dentry *d = oe->lowerstack[i].dentry;
147
148 if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
149 ret = d->d_op->d_weak_revalidate(d, flags);
150 if (ret <= 0)
151 break;
152 }
153 }
154 return ret;
155}
156
157static const struct dentry_operations ovl_dentry_operations = {
158 .d_release = ovl_dentry_release,
159 .d_real = ovl_d_real,
160};
161
162static const struct dentry_operations ovl_reval_dentry_operations = {
163 .d_release = ovl_dentry_release,
164 .d_real = ovl_d_real,
165 .d_revalidate = ovl_dentry_revalidate,
166 .d_weak_revalidate = ovl_dentry_weak_revalidate,
167};
168
169static struct kmem_cache *ovl_inode_cachep;
170
171static struct inode *ovl_alloc_inode(struct super_block *sb)
172{
173 struct ovl_inode *oi = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL);
174
175 if (!oi)
176 return NULL;
177
178 oi->cache = NULL;
179 oi->redirect = NULL;
180 oi->version = 0;
181 oi->flags = 0;
182 oi->__upperdentry = NULL;
183 oi->lower = NULL;
184 oi->lowerdata = NULL;
185 mutex_init(&oi->lock);
186
187 return &oi->vfs_inode;
188}
189
190static void ovl_free_inode(struct inode *inode)
191{
192 struct ovl_inode *oi = OVL_I(inode);
193
194 kfree(oi->redirect);
195 mutex_destroy(&oi->lock);
196 kmem_cache_free(ovl_inode_cachep, oi);
197}
198
199static void ovl_destroy_inode(struct inode *inode)
200{
201 struct ovl_inode *oi = OVL_I(inode);
202
203 dput(oi->__upperdentry);
204 iput(oi->lower);
205 if (S_ISDIR(inode->i_mode))
206 ovl_dir_cache_free(inode);
207 else
208 iput(oi->lowerdata);
209}
210
211static void ovl_free_fs(struct ovl_fs *ofs)
212{
213 unsigned i;
214
215 iput(ofs->workbasedir_trap);
216 iput(ofs->indexdir_trap);
217 iput(ofs->workdir_trap);
218 iput(ofs->upperdir_trap);
219 dput(ofs->indexdir);
220 dput(ofs->workdir);
221 if (ofs->workdir_locked)
222 ovl_inuse_unlock(ofs->workbasedir);
223 dput(ofs->workbasedir);
224 if (ofs->upperdir_locked)
225 ovl_inuse_unlock(ofs->upper_mnt->mnt_root);
226 mntput(ofs->upper_mnt);
227 for (i = 0; i < ofs->numlower; i++) {
228 iput(ofs->lower_layers[i].trap);
229 mntput(ofs->lower_layers[i].mnt);
230 }
231 for (i = 0; i < ofs->numlowerfs; i++)
232 free_anon_bdev(ofs->lower_fs[i].pseudo_dev);
233 kfree(ofs->lower_layers);
234 kfree(ofs->lower_fs);
235
236 kfree(ofs->config.lowerdir);
237 kfree(ofs->config.upperdir);
238 kfree(ofs->config.workdir);
239 kfree(ofs->config.redirect_mode);
240 if (ofs->creator_cred)
241 put_cred(ofs->creator_cred);
242 kfree(ofs);
243}
244
245static void ovl_put_super(struct super_block *sb)
246{
247 struct ovl_fs *ofs = sb->s_fs_info;
248
249 ovl_free_fs(ofs);
250}
251
252
253static int ovl_sync_fs(struct super_block *sb, int wait)
254{
255 struct ovl_fs *ofs = sb->s_fs_info;
256 struct super_block *upper_sb;
257 int ret;
258
259 if (!ofs->upper_mnt)
260 return 0;
261
262
263
264
265
266
267
268
269
270 if (!wait)
271 return 0;
272
273 upper_sb = ofs->upper_mnt->mnt_sb;
274
275 down_read(&upper_sb->s_umount);
276 ret = sync_filesystem(upper_sb);
277 up_read(&upper_sb->s_umount);
278
279 return ret;
280}
281
282
283
284
285
286
287
288
289
290static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
291{
292 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
293 struct dentry *root_dentry = dentry->d_sb->s_root;
294 struct path path;
295 int err;
296
297 ovl_path_real(root_dentry, &path);
298
299 err = vfs_statfs(&path, buf);
300 if (!err) {
301 buf->f_namelen = ofs->namelen;
302 buf->f_type = OVERLAYFS_SUPER_MAGIC;
303 }
304
305 return err;
306}
307
308
309static bool ovl_force_readonly(struct ovl_fs *ofs)
310{
311 return (!ofs->upper_mnt || !ofs->workdir);
312}
313
314static const char *ovl_redirect_mode_def(void)
315{
316 return ovl_redirect_dir_def ? "on" : "off";
317}
318
319enum {
320 OVL_XINO_OFF,
321 OVL_XINO_AUTO,
322 OVL_XINO_ON,
323};
324
325static const char * const ovl_xino_str[] = {
326 "off",
327 "auto",
328 "on",
329};
330
331static inline int ovl_xino_def(void)
332{
333 return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF;
334}
335
336
337
338
339
340
341
342static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
343{
344 struct super_block *sb = dentry->d_sb;
345 struct ovl_fs *ofs = sb->s_fs_info;
346
347 seq_show_option(m, "lowerdir", ofs->config.lowerdir);
348 if (ofs->config.upperdir) {
349 seq_show_option(m, "upperdir", ofs->config.upperdir);
350 seq_show_option(m, "workdir", ofs->config.workdir);
351 }
352 if (ofs->config.default_permissions)
353 seq_puts(m, ",default_permissions");
354 if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0)
355 seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode);
356 if (ofs->config.index != ovl_index_def)
357 seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
358 if (ofs->config.nfs_export != ovl_nfs_export_def)
359 seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
360 "on" : "off");
361 if (ofs->config.xino != ovl_xino_def())
362 seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]);
363 if (ofs->config.metacopy != ovl_metacopy_def)
364 seq_printf(m, ",metacopy=%s",
365 ofs->config.metacopy ? "on" : "off");
366 return 0;
367}
368
369static int ovl_remount(struct super_block *sb, int *flags, char *data)
370{
371 struct ovl_fs *ofs = sb->s_fs_info;
372
373 if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs))
374 return -EROFS;
375
376 return 0;
377}
378
379static const struct super_operations ovl_super_operations = {
380 .alloc_inode = ovl_alloc_inode,
381 .free_inode = ovl_free_inode,
382 .destroy_inode = ovl_destroy_inode,
383 .drop_inode = generic_delete_inode,
384 .put_super = ovl_put_super,
385 .sync_fs = ovl_sync_fs,
386 .statfs = ovl_statfs,
387 .show_options = ovl_show_options,
388 .remount_fs = ovl_remount,
389};
390
391enum {
392 OPT_LOWERDIR,
393 OPT_UPPERDIR,
394 OPT_WORKDIR,
395 OPT_DEFAULT_PERMISSIONS,
396 OPT_REDIRECT_DIR,
397 OPT_INDEX_ON,
398 OPT_INDEX_OFF,
399 OPT_NFS_EXPORT_ON,
400 OPT_NFS_EXPORT_OFF,
401 OPT_XINO_ON,
402 OPT_XINO_OFF,
403 OPT_XINO_AUTO,
404 OPT_METACOPY_ON,
405 OPT_METACOPY_OFF,
406 OPT_ERR,
407};
408
409static const match_table_t ovl_tokens = {
410 {OPT_LOWERDIR, "lowerdir=%s"},
411 {OPT_UPPERDIR, "upperdir=%s"},
412 {OPT_WORKDIR, "workdir=%s"},
413 {OPT_DEFAULT_PERMISSIONS, "default_permissions"},
414 {OPT_REDIRECT_DIR, "redirect_dir=%s"},
415 {OPT_INDEX_ON, "index=on"},
416 {OPT_INDEX_OFF, "index=off"},
417 {OPT_NFS_EXPORT_ON, "nfs_export=on"},
418 {OPT_NFS_EXPORT_OFF, "nfs_export=off"},
419 {OPT_XINO_ON, "xino=on"},
420 {OPT_XINO_OFF, "xino=off"},
421 {OPT_XINO_AUTO, "xino=auto"},
422 {OPT_METACOPY_ON, "metacopy=on"},
423 {OPT_METACOPY_OFF, "metacopy=off"},
424 {OPT_ERR, NULL}
425};
426
427static char *ovl_next_opt(char **s)
428{
429 char *sbegin = *s;
430 char *p;
431
432 if (sbegin == NULL)
433 return NULL;
434
435 for (p = sbegin; *p; p++) {
436 if (*p == '\\') {
437 p++;
438 if (!*p)
439 break;
440 } else if (*p == ',') {
441 *p = '\0';
442 *s = p + 1;
443 return sbegin;
444 }
445 }
446 *s = NULL;
447 return sbegin;
448}
449
450static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode)
451{
452 if (strcmp(mode, "on") == 0) {
453 config->redirect_dir = true;
454
455
456
457
458 config->redirect_follow = true;
459 } else if (strcmp(mode, "follow") == 0) {
460 config->redirect_follow = true;
461 } else if (strcmp(mode, "off") == 0) {
462 if (ovl_redirect_always_follow)
463 config->redirect_follow = true;
464 } else if (strcmp(mode, "nofollow") != 0) {
465 pr_err("overlayfs: bad mount option \"redirect_dir=%s\"\n",
466 mode);
467 return -EINVAL;
468 }
469
470 return 0;
471}
472
473static int ovl_parse_opt(char *opt, struct ovl_config *config)
474{
475 char *p;
476 int err;
477 bool metacopy_opt = false, redirect_opt = false;
478
479 config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL);
480 if (!config->redirect_mode)
481 return -ENOMEM;
482
483 while ((p = ovl_next_opt(&opt)) != NULL) {
484 int token;
485 substring_t args[MAX_OPT_ARGS];
486
487 if (!*p)
488 continue;
489
490 token = match_token(p, ovl_tokens, args);
491 switch (token) {
492 case OPT_UPPERDIR:
493 kfree(config->upperdir);
494 config->upperdir = match_strdup(&args[0]);
495 if (!config->upperdir)
496 return -ENOMEM;
497 break;
498
499 case OPT_LOWERDIR:
500 kfree(config->lowerdir);
501 config->lowerdir = match_strdup(&args[0]);
502 if (!config->lowerdir)
503 return -ENOMEM;
504 break;
505
506 case OPT_WORKDIR:
507 kfree(config->workdir);
508 config->workdir = match_strdup(&args[0]);
509 if (!config->workdir)
510 return -ENOMEM;
511 break;
512
513 case OPT_DEFAULT_PERMISSIONS:
514 config->default_permissions = true;
515 break;
516
517 case OPT_REDIRECT_DIR:
518 kfree(config->redirect_mode);
519 config->redirect_mode = match_strdup(&args[0]);
520 if (!config->redirect_mode)
521 return -ENOMEM;
522 redirect_opt = true;
523 break;
524
525 case OPT_INDEX_ON:
526 config->index = true;
527 break;
528
529 case OPT_INDEX_OFF:
530 config->index = false;
531 break;
532
533 case OPT_NFS_EXPORT_ON:
534 config->nfs_export = true;
535 break;
536
537 case OPT_NFS_EXPORT_OFF:
538 config->nfs_export = false;
539 break;
540
541 case OPT_XINO_ON:
542 config->xino = OVL_XINO_ON;
543 break;
544
545 case OPT_XINO_OFF:
546 config->xino = OVL_XINO_OFF;
547 break;
548
549 case OPT_XINO_AUTO:
550 config->xino = OVL_XINO_AUTO;
551 break;
552
553 case OPT_METACOPY_ON:
554 config->metacopy = true;
555 metacopy_opt = true;
556 break;
557
558 case OPT_METACOPY_OFF:
559 config->metacopy = false;
560 break;
561
562 default:
563 pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
564 return -EINVAL;
565 }
566 }
567
568
569 if (!config->upperdir && config->workdir) {
570 pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
571 config->workdir);
572 kfree(config->workdir);
573 config->workdir = NULL;
574 }
575
576 err = ovl_parse_redirect_mode(config, config->redirect_mode);
577 if (err)
578 return err;
579
580
581
582
583
584 if (!config->upperdir && config->redirect_follow)
585 config->redirect_dir = true;
586
587
588 if (config->metacopy && !config->redirect_dir) {
589 if (metacopy_opt && redirect_opt) {
590 pr_err("overlayfs: conflicting options: metacopy=on,redirect_dir=%s\n",
591 config->redirect_mode);
592 return -EINVAL;
593 }
594 if (redirect_opt) {
595
596
597
598
599 pr_info("overlayfs: disabling metacopy due to redirect_dir=%s\n",
600 config->redirect_mode);
601 config->metacopy = false;
602 } else {
603
604 config->redirect_follow = config->redirect_dir = true;
605 }
606 }
607
608 return 0;
609}
610
611#define OVL_WORKDIR_NAME "work"
612#define OVL_INDEXDIR_NAME "index"
613
614static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
615 const char *name, bool persist)
616{
617 struct inode *dir = ofs->workbasedir->d_inode;
618 struct vfsmount *mnt = ofs->upper_mnt;
619 struct dentry *work;
620 int err;
621 bool retried = false;
622 bool locked = false;
623
624 inode_lock_nested(dir, I_MUTEX_PARENT);
625 locked = true;
626
627retry:
628 work = lookup_one_len(name, ofs->workbasedir, strlen(name));
629
630 if (!IS_ERR(work)) {
631 struct iattr attr = {
632 .ia_valid = ATTR_MODE,
633 .ia_mode = S_IFDIR | 0,
634 };
635
636 if (work->d_inode) {
637 err = -EEXIST;
638 if (retried)
639 goto out_dput;
640
641 if (persist)
642 goto out_unlock;
643
644 retried = true;
645 ovl_workdir_cleanup(dir, mnt, work, 0);
646 dput(work);
647 goto retry;
648 }
649
650 work = ovl_create_real(dir, work, OVL_CATTR(attr.ia_mode));
651 err = PTR_ERR(work);
652 if (IS_ERR(work))
653 goto out_err;
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668 err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT);
669 if (err && err != -ENODATA && err != -EOPNOTSUPP)
670 goto out_dput;
671
672 err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS);
673 if (err && err != -ENODATA && err != -EOPNOTSUPP)
674 goto out_dput;
675
676
677 inode_lock(work->d_inode);
678 err = notify_change(work, &attr, NULL);
679 inode_unlock(work->d_inode);
680 if (err)
681 goto out_dput;
682 } else {
683 err = PTR_ERR(work);
684 goto out_err;
685 }
686out_unlock:
687 if (locked)
688 inode_unlock(dir);
689
690 return work;
691
692out_dput:
693 dput(work);
694out_err:
695 pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
696 ofs->config.workdir, name, -err);
697 work = NULL;
698 goto out_unlock;
699}
700
701static void ovl_unescape(char *s)
702{
703 char *d = s;
704
705 for (;; s++, d++) {
706 if (*s == '\\')
707 s++;
708 *d = *s;
709 if (!*s)
710 break;
711 }
712}
713
714static int ovl_mount_dir_noesc(const char *name, struct path *path)
715{
716 int err = -EINVAL;
717
718 if (!*name) {
719 pr_err("overlayfs: empty lowerdir\n");
720 goto out;
721 }
722 err = kern_path(name, LOOKUP_FOLLOW, path);
723 if (err) {
724 pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
725 goto out;
726 }
727 err = -EINVAL;
728 if (ovl_dentry_weird(path->dentry)) {
729 pr_err("overlayfs: filesystem on '%s' not supported\n", name);
730 goto out_put;
731 }
732 if (!d_is_dir(path->dentry)) {
733 pr_err("overlayfs: '%s' not a directory\n", name);
734 goto out_put;
735 }
736 return 0;
737
738out_put:
739 path_put_init(path);
740out:
741 return err;
742}
743
744static int ovl_mount_dir(const char *name, struct path *path)
745{
746 int err = -ENOMEM;
747 char *tmp = kstrdup(name, GFP_KERNEL);
748
749 if (tmp) {
750 ovl_unescape(tmp);
751 err = ovl_mount_dir_noesc(tmp, path);
752
753 if (!err)
754 if (ovl_dentry_remote(path->dentry)) {
755 pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
756 tmp);
757 path_put_init(path);
758 err = -EINVAL;
759 }
760 kfree(tmp);
761 }
762 return err;
763}
764
765static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs,
766 const char *name)
767{
768 struct kstatfs statfs;
769 int err = vfs_statfs(path, &statfs);
770
771 if (err)
772 pr_err("overlayfs: statfs failed on '%s'\n", name);
773 else
774 ofs->namelen = max(ofs->namelen, statfs.f_namelen);
775
776 return err;
777}
778
779static int ovl_lower_dir(const char *name, struct path *path,
780 struct ovl_fs *ofs, int *stack_depth, bool *remote)
781{
782 int fh_type;
783 int err;
784
785 err = ovl_mount_dir_noesc(name, path);
786 if (err)
787 goto out;
788
789 err = ovl_check_namelen(path, ofs, name);
790 if (err)
791 goto out_put;
792
793 *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
794
795 if (ovl_dentry_remote(path->dentry))
796 *remote = true;
797
798
799
800
801
802 fh_type = ovl_can_decode_fh(path->dentry->d_sb);
803 if ((ofs->config.nfs_export ||
804 (ofs->config.index && ofs->config.upperdir)) && !fh_type) {
805 ofs->config.index = false;
806 ofs->config.nfs_export = false;
807 pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n",
808 name);
809 }
810
811
812 if (fh_type != FILEID_INO32_GEN)
813 ofs->xino_bits = 0;
814
815 return 0;
816
817out_put:
818 path_put_init(path);
819out:
820 return err;
821}
822
823
824static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
825{
826 bool ok = false;
827
828 if (workdir != upperdir) {
829 ok = (lock_rename(workdir, upperdir) == NULL);
830 unlock_rename(workdir, upperdir);
831 }
832 return ok;
833}
834
835static unsigned int ovl_split_lowerdirs(char *str)
836{
837 unsigned int ctr = 1;
838 char *s, *d;
839
840 for (s = d = str;; s++, d++) {
841 if (*s == '\\') {
842 s++;
843 } else if (*s == ':') {
844 *d = '\0';
845 ctr++;
846 continue;
847 }
848 *d = *s;
849 if (!*s)
850 break;
851 }
852 return ctr;
853}
854
855static int __maybe_unused
856ovl_posix_acl_xattr_get(const struct xattr_handler *handler,
857 struct dentry *dentry, struct inode *inode,
858 const char *name, void *buffer, size_t size)
859{
860 return ovl_xattr_get(dentry, inode, handler->name, buffer, size);
861}
862
863static int __maybe_unused
864ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
865 struct dentry *dentry, struct inode *inode,
866 const char *name, const void *value,
867 size_t size, int flags)
868{
869 struct dentry *workdir = ovl_workdir(dentry);
870 struct inode *realinode = ovl_inode_real(inode);
871 struct posix_acl *acl = NULL;
872 int err;
873
874
875 if (value) {
876 acl = posix_acl_from_xattr(&init_user_ns, value, size);
877 if (IS_ERR(acl))
878 return PTR_ERR(acl);
879 }
880 err = -EOPNOTSUPP;
881 if (!IS_POSIXACL(d_inode(workdir)))
882 goto out_acl_release;
883 if (!realinode->i_op->set_acl)
884 goto out_acl_release;
885 if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) {
886 err = acl ? -EACCES : 0;
887 goto out_acl_release;
888 }
889 err = -EPERM;
890 if (!inode_owner_or_capable(inode))
891 goto out_acl_release;
892
893 posix_acl_release(acl);
894
895
896
897
898
899 if (unlikely(inode->i_mode & S_ISGID) &&
900 handler->flags == ACL_TYPE_ACCESS &&
901 !in_group_p(inode->i_gid) &&
902 !capable_wrt_inode_uidgid(inode, CAP_FSETID)) {
903 struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
904
905 err = ovl_setattr(dentry, &iattr);
906 if (err)
907 return err;
908 }
909
910 err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags);
911 if (!err)
912 ovl_copyattr(ovl_inode_real(inode), inode);
913
914 return err;
915
916out_acl_release:
917 posix_acl_release(acl);
918 return err;
919}
920
921static int ovl_own_xattr_get(const struct xattr_handler *handler,
922 struct dentry *dentry, struct inode *inode,
923 const char *name, void *buffer, size_t size)
924{
925 return -EOPNOTSUPP;
926}
927
928static int ovl_own_xattr_set(const struct xattr_handler *handler,
929 struct dentry *dentry, struct inode *inode,
930 const char *name, const void *value,
931 size_t size, int flags)
932{
933 return -EOPNOTSUPP;
934}
935
936static int ovl_other_xattr_get(const struct xattr_handler *handler,
937 struct dentry *dentry, struct inode *inode,
938 const char *name, void *buffer, size_t size)
939{
940 return ovl_xattr_get(dentry, inode, name, buffer, size);
941}
942
943static int ovl_other_xattr_set(const struct xattr_handler *handler,
944 struct dentry *dentry, struct inode *inode,
945 const char *name, const void *value,
946 size_t size, int flags)
947{
948 return ovl_xattr_set(dentry, inode, name, value, size, flags);
949}
950
951static const struct xattr_handler __maybe_unused
952ovl_posix_acl_access_xattr_handler = {
953 .name = XATTR_NAME_POSIX_ACL_ACCESS,
954 .flags = ACL_TYPE_ACCESS,
955 .get = ovl_posix_acl_xattr_get,
956 .set = ovl_posix_acl_xattr_set,
957};
958
959static const struct xattr_handler __maybe_unused
960ovl_posix_acl_default_xattr_handler = {
961 .name = XATTR_NAME_POSIX_ACL_DEFAULT,
962 .flags = ACL_TYPE_DEFAULT,
963 .get = ovl_posix_acl_xattr_get,
964 .set = ovl_posix_acl_xattr_set,
965};
966
967static const struct xattr_handler ovl_own_xattr_handler = {
968 .prefix = OVL_XATTR_PREFIX,
969 .get = ovl_own_xattr_get,
970 .set = ovl_own_xattr_set,
971};
972
973static const struct xattr_handler ovl_other_xattr_handler = {
974 .prefix = "",
975 .get = ovl_other_xattr_get,
976 .set = ovl_other_xattr_set,
977};
978
979static const struct xattr_handler *ovl_xattr_handlers[] = {
980#ifdef CONFIG_FS_POSIX_ACL
981 &ovl_posix_acl_access_xattr_handler,
982 &ovl_posix_acl_default_xattr_handler,
983#endif
984 &ovl_own_xattr_handler,
985 &ovl_other_xattr_handler,
986 NULL
987};
988
989static int ovl_setup_trap(struct super_block *sb, struct dentry *dir,
990 struct inode **ptrap, const char *name)
991{
992 struct inode *trap;
993 int err;
994
995 trap = ovl_get_trap_inode(sb, dir);
996 err = PTR_ERR_OR_ZERO(trap);
997 if (err) {
998 if (err == -ELOOP)
999 pr_err("overlayfs: conflicting %s path\n", name);
1000 return err;
1001 }
1002
1003 *ptrap = trap;
1004 return 0;
1005}
1006
1007
1008
1009
1010
1011
1012
1013static int ovl_report_in_use(struct ovl_fs *ofs, const char *name)
1014{
1015 if (ofs->config.index) {
1016 pr_err("overlayfs: %s is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.\n",
1017 name);
1018 return -EBUSY;
1019 } else {
1020 pr_warn("overlayfs: %s is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.\n",
1021 name);
1022 return 0;
1023 }
1024}
1025
1026static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
1027 struct path *upperpath)
1028{
1029 struct vfsmount *upper_mnt;
1030 int err;
1031
1032 err = ovl_mount_dir(ofs->config.upperdir, upperpath);
1033 if (err)
1034 goto out;
1035
1036
1037 if (sb_rdonly(upperpath->mnt->mnt_sb)) {
1038 pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
1039 err = -EINVAL;
1040 goto out;
1041 }
1042
1043 err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir);
1044 if (err)
1045 goto out;
1046
1047 err = ovl_setup_trap(sb, upperpath->dentry, &ofs->upperdir_trap,
1048 "upperdir");
1049 if (err)
1050 goto out;
1051
1052 upper_mnt = clone_private_mount(upperpath);
1053 err = PTR_ERR(upper_mnt);
1054 if (IS_ERR(upper_mnt)) {
1055 pr_err("overlayfs: failed to clone upperpath\n");
1056 goto out;
1057 }
1058
1059
1060 upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
1061 ofs->upper_mnt = upper_mnt;
1062
1063 if (ovl_inuse_trylock(ofs->upper_mnt->mnt_root)) {
1064 ofs->upperdir_locked = true;
1065 } else {
1066 err = ovl_report_in_use(ofs, "upperdir");
1067 if (err)
1068 goto out;
1069 }
1070
1071 err = 0;
1072out:
1073 return err;
1074}
1075
1076static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
1077 struct path *workpath)
1078{
1079 struct vfsmount *mnt = ofs->upper_mnt;
1080 struct dentry *temp;
1081 int fh_type;
1082 int err;
1083
1084 err = mnt_want_write(mnt);
1085 if (err)
1086 return err;
1087
1088 ofs->workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false);
1089 if (!ofs->workdir)
1090 goto out;
1091
1092 err = ovl_setup_trap(sb, ofs->workdir, &ofs->workdir_trap, "workdir");
1093 if (err)
1094 goto out;
1095
1096
1097
1098
1099
1100
1101
1102 err = ovl_check_d_type_supported(workpath);
1103 if (err < 0)
1104 goto out;
1105
1106
1107
1108
1109
1110 if (!err)
1111 pr_warn("overlayfs: upper fs needs to support d_type.\n");
1112
1113
1114 temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0);
1115 ofs->tmpfile = !IS_ERR(temp);
1116 if (ofs->tmpfile)
1117 dput(temp);
1118 else
1119 pr_warn("overlayfs: upper fs does not support tmpfile.\n");
1120
1121
1122
1123
1124 err = ovl_do_setxattr(ofs->workdir, OVL_XATTR_OPAQUE, "0", 1, 0);
1125 if (err) {
1126 ofs->noxattr = true;
1127 ofs->config.index = false;
1128 ofs->config.metacopy = false;
1129 pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off and metacopy=off.\n");
1130 err = 0;
1131 } else {
1132 vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE);
1133 }
1134
1135
1136 fh_type = ovl_can_decode_fh(ofs->workdir->d_sb);
1137 if (ofs->config.index && !fh_type) {
1138 ofs->config.index = false;
1139 pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
1140 }
1141
1142
1143 if (fh_type != FILEID_INO32_GEN)
1144 ofs->xino_bits = 0;
1145
1146
1147 if (ofs->config.nfs_export && !ofs->config.index) {
1148 pr_warn("overlayfs: NFS export requires \"index=on\", falling back to nfs_export=off.\n");
1149 ofs->config.nfs_export = false;
1150 }
1151out:
1152 mnt_drop_write(mnt);
1153 return err;
1154}
1155
1156static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs,
1157 struct path *upperpath)
1158{
1159 int err;
1160 struct path workpath = { };
1161
1162 err = ovl_mount_dir(ofs->config.workdir, &workpath);
1163 if (err)
1164 goto out;
1165
1166 err = -EINVAL;
1167 if (upperpath->mnt != workpath.mnt) {
1168 pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
1169 goto out;
1170 }
1171 if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) {
1172 pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
1173 goto out;
1174 }
1175
1176 ofs->workbasedir = dget(workpath.dentry);
1177
1178 if (ovl_inuse_trylock(ofs->workbasedir)) {
1179 ofs->workdir_locked = true;
1180 } else {
1181 err = ovl_report_in_use(ofs, "workdir");
1182 if (err)
1183 goto out;
1184 }
1185
1186 err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap,
1187 "workdir");
1188 if (err)
1189 goto out;
1190
1191 err = ovl_make_workdir(sb, ofs, &workpath);
1192
1193out:
1194 path_put(&workpath);
1195
1196 return err;
1197}
1198
1199static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs,
1200 struct ovl_entry *oe, struct path *upperpath)
1201{
1202 struct vfsmount *mnt = ofs->upper_mnt;
1203 int err;
1204
1205 err = mnt_want_write(mnt);
1206 if (err)
1207 return err;
1208
1209
1210 err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry,
1211 true);
1212 if (err) {
1213 pr_err("overlayfs: failed to verify upper root origin\n");
1214 goto out;
1215 }
1216
1217 ofs->indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true);
1218 if (ofs->indexdir) {
1219 err = ovl_setup_trap(sb, ofs->indexdir, &ofs->indexdir_trap,
1220 "indexdir");
1221 if (err)
1222 goto out;
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232 if (ovl_check_origin_xattr(ofs->indexdir)) {
1233 err = ovl_verify_set_fh(ofs->indexdir, OVL_XATTR_ORIGIN,
1234 upperpath->dentry, true, false);
1235 if (err)
1236 pr_err("overlayfs: failed to verify index dir 'origin' xattr\n");
1237 }
1238 err = ovl_verify_upper(ofs->indexdir, upperpath->dentry, true);
1239 if (err)
1240 pr_err("overlayfs: failed to verify index dir 'upper' xattr\n");
1241
1242
1243 if (!err)
1244 err = ovl_indexdir_cleanup(ofs);
1245 }
1246 if (err || !ofs->indexdir)
1247 pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
1248
1249out:
1250 mnt_drop_write(mnt);
1251 return err;
1252}
1253
1254static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid)
1255{
1256 unsigned int i;
1257
1258 if (!ofs->config.nfs_export && !ofs->upper_mnt)
1259 return true;
1260
1261 for (i = 0; i < ofs->numlowerfs; i++) {
1262
1263
1264
1265
1266
1267
1268
1269 if (uuid_equal(&ofs->lower_fs[i].sb->s_uuid, uuid)) {
1270 ofs->lower_fs[i].bad_uuid = true;
1271 return false;
1272 }
1273 }
1274 return true;
1275}
1276
1277
1278static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path)
1279{
1280 struct super_block *sb = path->mnt->mnt_sb;
1281 unsigned int i;
1282 dev_t dev;
1283 int err;
1284 bool bad_uuid = false;
1285
1286
1287 if (ofs->upper_mnt && ofs->upper_mnt->mnt_sb == sb)
1288 return 0;
1289
1290 for (i = 0; i < ofs->numlowerfs; i++) {
1291 if (ofs->lower_fs[i].sb == sb)
1292 return i + 1;
1293 }
1294
1295 if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) {
1296 bad_uuid = true;
1297 if (ofs->config.index || ofs->config.nfs_export) {
1298 ofs->config.index = false;
1299 ofs->config.nfs_export = false;
1300 pr_warn("overlayfs: %s uuid detected in lower fs '%pd2', falling back to index=off,nfs_export=off.\n",
1301 uuid_is_null(&sb->s_uuid) ? "null" :
1302 "conflicting",
1303 path->dentry);
1304 }
1305 }
1306
1307 err = get_anon_bdev(&dev);
1308 if (err) {
1309 pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
1310 return err;
1311 }
1312
1313 ofs->lower_fs[ofs->numlowerfs].sb = sb;
1314 ofs->lower_fs[ofs->numlowerfs].pseudo_dev = dev;
1315 ofs->lower_fs[ofs->numlowerfs].bad_uuid = bad_uuid;
1316 ofs->numlowerfs++;
1317
1318 return ofs->numlowerfs;
1319}
1320
1321static int ovl_get_lower_layers(struct super_block *sb, struct ovl_fs *ofs,
1322 struct path *stack, unsigned int numlower)
1323{
1324 int err;
1325 unsigned int i;
1326
1327 err = -ENOMEM;
1328 ofs->lower_layers = kcalloc(numlower, sizeof(struct ovl_layer),
1329 GFP_KERNEL);
1330 if (ofs->lower_layers == NULL)
1331 goto out;
1332
1333 ofs->lower_fs = kcalloc(numlower, sizeof(struct ovl_sb),
1334 GFP_KERNEL);
1335 if (ofs->lower_fs == NULL)
1336 goto out;
1337
1338 for (i = 0; i < numlower; i++) {
1339 struct vfsmount *mnt;
1340 struct inode *trap;
1341 int fsid;
1342
1343 err = fsid = ovl_get_fsid(ofs, &stack[i]);
1344 if (err < 0)
1345 goto out;
1346
1347 err = ovl_setup_trap(sb, stack[i].dentry, &trap, "lowerdir");
1348 if (err)
1349 goto out;
1350
1351 if (ovl_is_inuse(stack[i].dentry)) {
1352 err = ovl_report_in_use(ofs, "lowerdir");
1353 if (err)
1354 goto out;
1355 }
1356
1357 mnt = clone_private_mount(&stack[i]);
1358 err = PTR_ERR(mnt);
1359 if (IS_ERR(mnt)) {
1360 pr_err("overlayfs: failed to clone lowerpath\n");
1361 iput(trap);
1362 goto out;
1363 }
1364
1365
1366
1367
1368
1369 mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
1370
1371 ofs->lower_layers[ofs->numlower].trap = trap;
1372 ofs->lower_layers[ofs->numlower].mnt = mnt;
1373 ofs->lower_layers[ofs->numlower].idx = i + 1;
1374 ofs->lower_layers[ofs->numlower].fsid = fsid;
1375 if (fsid) {
1376 ofs->lower_layers[ofs->numlower].fs =
1377 &ofs->lower_fs[fsid - 1];
1378 }
1379 ofs->numlower++;
1380 }
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390 if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) {
1391 ofs->xino_bits = 0;
1392 ofs->config.xino = OVL_XINO_OFF;
1393 } else if (ofs->config.xino == OVL_XINO_ON && !ofs->xino_bits) {
1394
1395
1396
1397
1398
1399 BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 31);
1400 ofs->xino_bits = ilog2(ofs->numlowerfs) + 1;
1401 }
1402
1403 if (ofs->xino_bits) {
1404 pr_info("overlayfs: \"xino\" feature enabled using %d upper inode bits.\n",
1405 ofs->xino_bits);
1406 }
1407
1408 err = 0;
1409out:
1410 return err;
1411}
1412
1413static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
1414 struct ovl_fs *ofs)
1415{
1416 int err;
1417 char *lowertmp, *lower;
1418 struct path *stack = NULL;
1419 unsigned int stacklen, numlower = 0, i;
1420 bool remote = false;
1421 struct ovl_entry *oe;
1422
1423 err = -ENOMEM;
1424 lowertmp = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
1425 if (!lowertmp)
1426 goto out_err;
1427
1428 err = -EINVAL;
1429 stacklen = ovl_split_lowerdirs(lowertmp);
1430 if (stacklen > OVL_MAX_STACK) {
1431 pr_err("overlayfs: too many lower directories, limit is %d\n",
1432 OVL_MAX_STACK);
1433 goto out_err;
1434 } else if (!ofs->config.upperdir && stacklen == 1) {
1435 pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
1436 goto out_err;
1437 } else if (!ofs->config.upperdir && ofs->config.nfs_export &&
1438 ofs->config.redirect_follow) {
1439 pr_warn("overlayfs: NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n");
1440 ofs->config.nfs_export = false;
1441 }
1442
1443 err = -ENOMEM;
1444 stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
1445 if (!stack)
1446 goto out_err;
1447
1448 err = -EINVAL;
1449 lower = lowertmp;
1450 for (numlower = 0; numlower < stacklen; numlower++) {
1451 err = ovl_lower_dir(lower, &stack[numlower], ofs,
1452 &sb->s_stack_depth, &remote);
1453 if (err)
1454 goto out_err;
1455
1456 lower = strchr(lower, '\0') + 1;
1457 }
1458
1459 err = -EINVAL;
1460 sb->s_stack_depth++;
1461 if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
1462 pr_err("overlayfs: maximum fs stacking depth exceeded\n");
1463 goto out_err;
1464 }
1465
1466 err = ovl_get_lower_layers(sb, ofs, stack, numlower);
1467 if (err)
1468 goto out_err;
1469
1470 err = -ENOMEM;
1471 oe = ovl_alloc_entry(numlower);
1472 if (!oe)
1473 goto out_err;
1474
1475 for (i = 0; i < numlower; i++) {
1476 oe->lowerstack[i].dentry = dget(stack[i].dentry);
1477 oe->lowerstack[i].layer = &ofs->lower_layers[i];
1478 }
1479
1480 if (remote)
1481 sb->s_d_op = &ovl_reval_dentry_operations;
1482 else
1483 sb->s_d_op = &ovl_dentry_operations;
1484
1485out:
1486 for (i = 0; i < numlower; i++)
1487 path_put(&stack[i]);
1488 kfree(stack);
1489 kfree(lowertmp);
1490
1491 return oe;
1492
1493out_err:
1494 oe = ERR_PTR(err);
1495 goto out;
1496}
1497
1498
1499
1500
1501
1502
1503static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs,
1504 struct dentry *dentry, const char *name)
1505{
1506 struct dentry *next = dentry, *parent;
1507 int err = 0;
1508
1509 if (!dentry)
1510 return 0;
1511
1512 parent = dget_parent(next);
1513
1514
1515 while (!err && parent != next) {
1516 if (ovl_lookup_trap_inode(sb, parent)) {
1517 err = -ELOOP;
1518 pr_err("overlayfs: overlapping %s path\n", name);
1519 } else if (ovl_is_inuse(parent)) {
1520 err = ovl_report_in_use(ofs, name);
1521 }
1522 next = parent;
1523 parent = dget_parent(next);
1524 dput(next);
1525 }
1526
1527 dput(parent);
1528
1529 return err;
1530}
1531
1532
1533
1534
1535static int ovl_check_overlapping_layers(struct super_block *sb,
1536 struct ovl_fs *ofs)
1537{
1538 int i, err;
1539
1540 if (ofs->upper_mnt) {
1541 err = ovl_check_layer(sb, ofs, ofs->upper_mnt->mnt_root,
1542 "upperdir");
1543 if (err)
1544 return err;
1545
1546
1547
1548
1549
1550
1551
1552
1553 err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir");
1554 if (err)
1555 return err;
1556 }
1557
1558 for (i = 0; i < ofs->numlower; i++) {
1559 err = ovl_check_layer(sb, ofs,
1560 ofs->lower_layers[i].mnt->mnt_root,
1561 "lowerdir");
1562 if (err)
1563 return err;
1564 }
1565
1566 return 0;
1567}
1568
1569static int ovl_fill_super(struct super_block *sb, void *data, int silent)
1570{
1571 struct path upperpath = { };
1572 struct dentry *root_dentry;
1573 struct ovl_entry *oe;
1574 struct ovl_fs *ofs;
1575 struct cred *cred;
1576 int err;
1577
1578 err = -ENOMEM;
1579 ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
1580 if (!ofs)
1581 goto out;
1582
1583 ofs->creator_cred = cred = prepare_creds();
1584 if (!cred)
1585 goto out_err;
1586
1587 ofs->config.index = ovl_index_def;
1588 ofs->config.nfs_export = ovl_nfs_export_def;
1589 ofs->config.xino = ovl_xino_def();
1590 ofs->config.metacopy = ovl_metacopy_def;
1591 err = ovl_parse_opt((char *) data, &ofs->config);
1592 if (err)
1593 goto out_err;
1594
1595 err = -EINVAL;
1596 if (!ofs->config.lowerdir) {
1597 if (!silent)
1598 pr_err("overlayfs: missing 'lowerdir'\n");
1599 goto out_err;
1600 }
1601
1602 sb->s_stack_depth = 0;
1603 sb->s_maxbytes = MAX_LFS_FILESIZE;
1604
1605 if (ofs->config.xino != OVL_XINO_OFF)
1606 ofs->xino_bits = BITS_PER_LONG - 32;
1607
1608
1609 sb->s_op = &ovl_super_operations;
1610
1611 if (ofs->config.upperdir) {
1612 if (!ofs->config.workdir) {
1613 pr_err("overlayfs: missing 'workdir'\n");
1614 goto out_err;
1615 }
1616
1617 err = ovl_get_upper(sb, ofs, &upperpath);
1618 if (err)
1619 goto out_err;
1620
1621 err = ovl_get_workdir(sb, ofs, &upperpath);
1622 if (err)
1623 goto out_err;
1624
1625 if (!ofs->workdir)
1626 sb->s_flags |= SB_RDONLY;
1627
1628 sb->s_stack_depth = ofs->upper_mnt->mnt_sb->s_stack_depth;
1629 sb->s_time_gran = ofs->upper_mnt->mnt_sb->s_time_gran;
1630
1631 }
1632 oe = ovl_get_lowerstack(sb, ofs);
1633 err = PTR_ERR(oe);
1634 if (IS_ERR(oe))
1635 goto out_err;
1636
1637
1638 if (!ofs->upper_mnt)
1639 sb->s_flags |= SB_RDONLY;
1640
1641 if (!(ovl_force_readonly(ofs)) && ofs->config.index) {
1642 err = ovl_get_indexdir(sb, ofs, oe, &upperpath);
1643 if (err)
1644 goto out_free_oe;
1645
1646
1647 if (!ofs->indexdir) {
1648 dput(ofs->workdir);
1649 ofs->workdir = NULL;
1650 sb->s_flags |= SB_RDONLY;
1651 }
1652
1653 }
1654
1655 err = ovl_check_overlapping_layers(sb, ofs);
1656 if (err)
1657 goto out_free_oe;
1658
1659
1660 if (!ofs->indexdir) {
1661 ofs->config.index = false;
1662 if (ofs->upper_mnt && ofs->config.nfs_export) {
1663 pr_warn("overlayfs: NFS export requires an index dir, falling back to nfs_export=off.\n");
1664 ofs->config.nfs_export = false;
1665 }
1666 }
1667
1668 if (ofs->config.metacopy && ofs->config.nfs_export) {
1669 pr_warn("overlayfs: NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n");
1670 ofs->config.nfs_export = false;
1671 }
1672
1673 if (ofs->config.nfs_export)
1674 sb->s_export_op = &ovl_export_operations;
1675
1676
1677 cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);
1678
1679 sb->s_magic = OVERLAYFS_SUPER_MAGIC;
1680 sb->s_xattr = ovl_xattr_handlers;
1681 sb->s_fs_info = ofs;
1682 sb->s_flags |= SB_POSIXACL;
1683
1684 err = -ENOMEM;
1685 root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
1686 if (!root_dentry)
1687 goto out_free_oe;
1688
1689 root_dentry->d_fsdata = oe;
1690
1691 mntput(upperpath.mnt);
1692 if (upperpath.dentry) {
1693 ovl_dentry_set_upper_alias(root_dentry);
1694 if (ovl_is_impuredir(upperpath.dentry))
1695 ovl_set_flag(OVL_IMPURE, d_inode(root_dentry));
1696 }
1697
1698
1699 ovl_set_flag(OVL_WHITEOUTS, d_inode(root_dentry));
1700 ovl_dentry_set_flag(OVL_E_CONNECTED, root_dentry);
1701 ovl_set_upperdata(d_inode(root_dentry));
1702 ovl_inode_init(d_inode(root_dentry), upperpath.dentry,
1703 ovl_dentry_lower(root_dentry), NULL);
1704
1705 sb->s_root = root_dentry;
1706
1707 return 0;
1708
1709out_free_oe:
1710 ovl_entry_stack_free(oe);
1711 kfree(oe);
1712out_err:
1713 path_put(&upperpath);
1714 ovl_free_fs(ofs);
1715out:
1716 return err;
1717}
1718
1719static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
1720 const char *dev_name, void *raw_data)
1721{
1722 return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
1723}
1724
1725static struct file_system_type ovl_fs_type = {
1726 .owner = THIS_MODULE,
1727 .name = "overlay",
1728 .mount = ovl_mount,
1729 .kill_sb = kill_anon_super,
1730};
1731MODULE_ALIAS_FS("overlay");
1732
1733static void ovl_inode_init_once(void *foo)
1734{
1735 struct ovl_inode *oi = foo;
1736
1737 inode_init_once(&oi->vfs_inode);
1738}
1739
1740static int __init ovl_init(void)
1741{
1742 int err;
1743
1744 ovl_inode_cachep = kmem_cache_create("ovl_inode",
1745 sizeof(struct ovl_inode), 0,
1746 (SLAB_RECLAIM_ACCOUNT|
1747 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
1748 ovl_inode_init_once);
1749 if (ovl_inode_cachep == NULL)
1750 return -ENOMEM;
1751
1752 err = register_filesystem(&ovl_fs_type);
1753 if (err)
1754 kmem_cache_destroy(ovl_inode_cachep);
1755
1756 return err;
1757}
1758
1759static void __exit ovl_exit(void)
1760{
1761 unregister_filesystem(&ovl_fs_type);
1762
1763
1764
1765
1766
1767 rcu_barrier();
1768 kmem_cache_destroy(ovl_inode_cachep);
1769
1770}
1771
1772module_init(ovl_init);
1773module_exit(ovl_exit);
1774
