1 /*
2 *
3 * Copyright (C) 2011 Novell Inc.
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 as published by
7 * the Free Software Foundation.
8 */
9
10 #include <linux/fs.h>
11 #include <linux/namei.h>
12 #include <linux/xattr.h>
13 #include <linux/security.h>
14 #include <linux/cred.h>
15 #include <linux/module.h>
16 #include <linux/posix_acl.h>
17 #include <linux/posix_acl_xattr.h>
18 #include <linux/atomic.h>
19 #include <linux/ratelimit.h>
20 #include "overlayfs.h"
21
22 static unsigned short ovl_redirect_max = 256;
23 module_param_named(redirect_max, ovl_redirect_max, ushort, 0644);
24 MODULE_PARM_DESC(ovl_redirect_max,
25 "Maximum length of absolute redirect xattr value");
26
ovl_cleanup(struct inode * wdir,struct dentry * wdentry)27 int ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
28 {
29 int err;
30
31 dget(wdentry);
32 if (d_is_dir(wdentry))
33 err = ovl_do_rmdir(wdir, wdentry);
34 else
35 err = ovl_do_unlink(wdir, wdentry);
36 dput(wdentry);
37
38 if (err) {
39 pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
40 wdentry, err);
41 }
42
43 return err;
44 }
45
ovl_lookup_temp(struct dentry * workdir)46 struct dentry *ovl_lookup_temp(struct dentry *workdir)
47 {
48 struct dentry *temp;
49 char name[20];
50 static atomic_t temp_id = ATOMIC_INIT(0);
51
52 /* counter is allowed to wrap, since temp dentries are ephemeral */
53 snprintf(name, sizeof(name), "#%x", atomic_inc_return(&temp_id));
54
55 temp = lookup_one_len(name, workdir, strlen(name));
56 if (!IS_ERR(temp) && temp->d_inode) {
57 pr_err("overlayfs: workdir/%s already exists\n", name);
58 dput(temp);
59 temp = ERR_PTR(-EIO);
60 }
61
62 return temp;
63 }
64
65 /* caller holds i_mutex on workdir */
ovl_whiteout(struct dentry * workdir,struct dentry * dentry)66 static struct dentry *ovl_whiteout(struct dentry *workdir,
67 struct dentry *dentry)
68 {
69 int err;
70 struct dentry *whiteout;
71 struct inode *wdir = workdir->d_inode;
72
73 whiteout = ovl_lookup_temp(workdir);
74 if (IS_ERR(whiteout))
75 return whiteout;
76
77 err = ovl_do_whiteout(wdir, whiteout);
78 if (err) {
79 dput(whiteout);
80 whiteout = ERR_PTR(err);
81 }
82
83 return whiteout;
84 }
85
ovl_create_real(struct inode * dir,struct dentry * newdentry,struct cattr * attr,struct dentry * hardlink,bool debug)86 int ovl_create_real(struct inode *dir, struct dentry *newdentry,
87 struct cattr *attr, struct dentry *hardlink, bool debug)
88 {
89 int err;
90
91 if (newdentry->d_inode)
92 return -ESTALE;
93
94 if (hardlink) {
95 err = ovl_do_link(hardlink, dir, newdentry, debug);
96 } else {
97 switch (attr->mode & S_IFMT) {
98 case S_IFREG:
99 err = ovl_do_create(dir, newdentry, attr->mode, debug);
100 break;
101
102 case S_IFDIR:
103 err = ovl_do_mkdir(dir, newdentry, attr->mode, debug);
104 break;
105
106 case S_IFCHR:
107 case S_IFBLK:
108 case S_IFIFO:
109 case S_IFSOCK:
110 err = ovl_do_mknod(dir, newdentry,
111 attr->mode, attr->rdev, debug);
112 break;
113
114 case S_IFLNK:
115 err = ovl_do_symlink(dir, newdentry, attr->link, debug);
116 break;
117
118 default:
119 err = -EPERM;
120 }
121 }
122 if (!err && WARN_ON(!newdentry->d_inode)) {
123 /*
124 * Not quite sure if non-instantiated dentry is legal or not.
125 * VFS doesn't seem to care so check and warn here.
126 */
127 err = -ENOENT;
128 }
129 return err;
130 }
131
ovl_set_opaque_xerr(struct dentry * dentry,struct dentry * upper,int xerr)132 static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper,
133 int xerr)
134 {
135 int err;
136
137 err = ovl_check_setxattr(dentry, upper, OVL_XATTR_OPAQUE, "y", 1, xerr);
138 if (!err)
139 ovl_dentry_set_opaque(dentry);
140
141 return err;
142 }
143
ovl_set_opaque(struct dentry * dentry,struct dentry * upperdentry)144 static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
145 {
146 /*
147 * Fail with -EIO when trying to create opaque dir and upper doesn't
148 * support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to
149 * return a specific error for noxattr case.
150 */
151 return ovl_set_opaque_xerr(dentry, upperdentry, -EIO);
152 }
153
154 /* Common operations required to be done after creation of file on upper */
ovl_instantiate(struct dentry * dentry,struct inode * inode,struct dentry * newdentry,bool hardlink)155 static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
156 struct dentry *newdentry, bool hardlink)
157 {
158 ovl_dentry_version_inc(dentry->d_parent, false);
159 ovl_dentry_set_upper_alias(dentry);
160 if (!hardlink) {
161 ovl_inode_update(inode, newdentry);
162 ovl_copyattr(newdentry->d_inode, inode);
163 } else {
164 WARN_ON(ovl_inode_real(inode) != d_inode(newdentry));
165 dput(newdentry);
166 inc_nlink(inode);
167 }
168 d_instantiate(dentry, inode);
169 /* Force lookup of new upper hardlink to find its lower */
170 if (hardlink)
171 d_drop(dentry);
172 }
173
ovl_type_merge(struct dentry * dentry)174 static bool ovl_type_merge(struct dentry *dentry)
175 {
176 return OVL_TYPE_MERGE(ovl_path_type(dentry));
177 }
178
ovl_type_origin(struct dentry * dentry)179 static bool ovl_type_origin(struct dentry *dentry)
180 {
181 return OVL_TYPE_ORIGIN(ovl_path_type(dentry));
182 }
183
ovl_create_upper(struct dentry * dentry,struct inode * inode,struct cattr * attr,struct dentry * hardlink)184 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
185 struct cattr *attr, struct dentry *hardlink)
186 {
187 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
188 struct inode *udir = upperdir->d_inode;
189 struct dentry *newdentry;
190 int err;
191
192 if (!hardlink && !IS_POSIXACL(udir))
193 attr->mode &= ~current_umask();
194
195 inode_lock_nested(udir, I_MUTEX_PARENT);
196 newdentry = lookup_one_len(dentry->d_name.name, upperdir,
197 dentry->d_name.len);
198 err = PTR_ERR(newdentry);
199 if (IS_ERR(newdentry))
200 goto out_unlock;
201 err = ovl_create_real(udir, newdentry, attr, hardlink, false);
202 if (err)
203 goto out_dput;
204
205 if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry)) {
206 /* Setting opaque here is just an optimization, allow to fail */
207 ovl_set_opaque(dentry, newdentry);
208 }
209
210 ovl_instantiate(dentry, inode, newdentry, !!hardlink);
211 newdentry = NULL;
212 out_dput:
213 dput(newdentry);
214 out_unlock:
215 inode_unlock(udir);
216 return err;
217 }
218
ovl_clear_empty(struct dentry * dentry,struct list_head * list)219 static struct dentry *ovl_clear_empty(struct dentry *dentry,
220 struct list_head *list)
221 {
222 struct dentry *workdir = ovl_workdir(dentry);
223 struct inode *wdir = workdir->d_inode;
224 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
225 struct inode *udir = upperdir->d_inode;
226 struct path upperpath;
227 struct dentry *upper;
228 struct dentry *opaquedir;
229 struct kstat stat;
230 int err;
231
232 if (WARN_ON(!workdir))
233 return ERR_PTR(-EROFS);
234
235 err = ovl_lock_rename_workdir(workdir, upperdir);
236 if (err)
237 goto out;
238
239 ovl_path_upper(dentry, &upperpath);
240 err = vfs_getattr(&upperpath, &stat,
241 STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
242 if (err)
243 goto out_unlock;
244
245 err = -ESTALE;
246 if (!S_ISDIR(stat.mode))
247 goto out_unlock;
248 upper = upperpath.dentry;
249 if (upper->d_parent->d_inode != udir)
250 goto out_unlock;
251
252 opaquedir = ovl_lookup_temp(workdir);
253 err = PTR_ERR(opaquedir);
254 if (IS_ERR(opaquedir))
255 goto out_unlock;
256
257 err = ovl_create_real(wdir, opaquedir,
258 &(struct cattr){.mode = stat.mode}, NULL, true);
259 if (err)
260 goto out_dput;
261
262 err = ovl_copy_xattr(upper, opaquedir);
263 if (err)
264 goto out_cleanup;
265
266 err = ovl_set_opaque(dentry, opaquedir);
267 if (err)
268 goto out_cleanup;
269
270 inode_lock(opaquedir->d_inode);
271 err = ovl_set_attr(opaquedir, &stat);
272 inode_unlock(opaquedir->d_inode);
273 if (err)
274 goto out_cleanup;
275
276 err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
277 if (err)
278 goto out_cleanup;
279
280 ovl_cleanup_whiteouts(upper, list);
281 ovl_cleanup(wdir, upper);
282 unlock_rename(workdir, upperdir);
283
284 /* dentry's upper doesn't match now, get rid of it */
285 d_drop(dentry);
286
287 return opaquedir;
288
289 out_cleanup:
290 ovl_cleanup(wdir, opaquedir);
291 out_dput:
292 dput(opaquedir);
293 out_unlock:
294 unlock_rename(workdir, upperdir);
295 out:
296 return ERR_PTR(err);
297 }
298
ovl_check_empty_and_clear(struct dentry * dentry)299 static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
300 {
301 int err;
302 struct dentry *ret = NULL;
303 enum ovl_path_type type = ovl_path_type(dentry);
304 LIST_HEAD(list);
305
306 err = ovl_check_empty_dir(dentry, &list);
307 if (err) {
308 ret = ERR_PTR(err);
309 goto out_free;
310 }
311
312 /*
313 * When removing an empty opaque directory, then it makes no sense to
314 * replace it with an exact replica of itself.
315 *
316 * If no upperdentry then skip clearing whiteouts.
317 *
318 * Can race with copy-up, since we don't hold the upperdir mutex.
319 * Doesn't matter, since copy-up can't create a non-empty directory
320 * from an empty one.
321 */
322 if (OVL_TYPE_UPPER(type) && OVL_TYPE_MERGE(type))
323 ret = ovl_clear_empty(dentry, &list);
324
325 out_free:
326 ovl_cache_free(&list);
327
328 return ret;
329 }
330
ovl_set_upper_acl(struct dentry * upperdentry,const char * name,const struct posix_acl * acl)331 static int ovl_set_upper_acl(struct dentry *upperdentry, const char *name,
332 const struct posix_acl *acl)
333 {
334 void *buffer;
335 size_t size;
336 int err;
337
338 if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl)
339 return 0;
340
341 size = posix_acl_to_xattr(NULL, acl, NULL, 0);
342 buffer = kmalloc(size, GFP_KERNEL);
343 if (!buffer)
344 return -ENOMEM;
345
346 size = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
347 err = size;
348 if (err < 0)
349 goto out_free;
350
351 err = vfs_setxattr(upperdentry, name, buffer, size, XATTR_CREATE);
352 out_free:
353 kfree(buffer);
354 return err;
355 }
356
ovl_create_over_whiteout(struct dentry * dentry,struct inode * inode,struct cattr * cattr,struct dentry * hardlink)357 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
358 struct cattr *cattr,
359 struct dentry *hardlink)
360 {
361 struct dentry *workdir = ovl_workdir(dentry);
362 struct inode *wdir = workdir->d_inode;
363 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
364 struct inode *udir = upperdir->d_inode;
365 struct dentry *upper;
366 struct dentry *newdentry;
367 int err;
368 struct posix_acl *acl, *default_acl;
369
370 if (WARN_ON(!workdir))
371 return -EROFS;
372
373 if (!hardlink) {
374 err = posix_acl_create(dentry->d_parent->d_inode,
375 &cattr->mode, &default_acl, &acl);
376 if (err)
377 return err;
378 }
379
380 err = ovl_lock_rename_workdir(workdir, upperdir);
381 if (err)
382 goto out;
383
384 newdentry = ovl_lookup_temp(workdir);
385 err = PTR_ERR(newdentry);
386 if (IS_ERR(newdentry))
387 goto out_unlock;
388
389 upper = lookup_one_len(dentry->d_name.name, upperdir,
390 dentry->d_name.len);
391 err = PTR_ERR(upper);
392 if (IS_ERR(upper))
393 goto out_dput;
394
395 err = -ESTALE;
396 if (d_is_negative(upper) || !IS_WHITEOUT(d_inode(upper)))
397 goto out_dput2;
398
399 err = ovl_create_real(wdir, newdentry, cattr, hardlink, true);
400 if (err)
401 goto out_dput2;
402
403 /*
404 * mode could have been mutilated due to umask (e.g. sgid directory)
405 */
406 if (!hardlink &&
407 !S_ISLNK(cattr->mode) &&
408 newdentry->d_inode->i_mode != cattr->mode) {
409 struct iattr attr = {
410 .ia_valid = ATTR_MODE,
411 .ia_mode = cattr->mode,
412 };
413 inode_lock(newdentry->d_inode);
414 err = notify_change(newdentry, &attr, NULL);
415 inode_unlock(newdentry->d_inode);
416 if (err)
417 goto out_cleanup;
418 }
419 if (!hardlink) {
420 err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_ACCESS,
421 acl);
422 if (err)
423 goto out_cleanup;
424
425 err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_DEFAULT,
426 default_acl);
427 if (err)
428 goto out_cleanup;
429 }
430
431 if (!hardlink && S_ISDIR(cattr->mode)) {
432 err = ovl_set_opaque(dentry, newdentry);
433 if (err)
434 goto out_cleanup;
435
436 err = ovl_do_rename(wdir, newdentry, udir, upper,
437 RENAME_EXCHANGE);
438 if (err)
439 goto out_cleanup;
440
441 ovl_cleanup(wdir, upper);
442 } else {
443 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
444 if (err)
445 goto out_cleanup;
446 }
447 ovl_instantiate(dentry, inode, newdentry, !!hardlink);
448 newdentry = NULL;
449 out_dput2:
450 dput(upper);
451 out_dput:
452 dput(newdentry);
453 out_unlock:
454 unlock_rename(workdir, upperdir);
455 out:
456 if (!hardlink) {
457 posix_acl_release(acl);
458 posix_acl_release(default_acl);
459 }
460 return err;
461
462 out_cleanup:
463 ovl_cleanup(wdir, newdentry);
464 goto out_dput2;
465 }
466
ovl_create_or_link(struct dentry * dentry,struct inode * inode,struct cattr * attr,struct dentry * hardlink,bool origin)467 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
468 struct cattr *attr, struct dentry *hardlink,
469 bool origin)
470 {
471 int err;
472 const struct cred *old_cred, *hold_cred = NULL;
473 struct cred *override_cred;
474 struct dentry *parent = dentry->d_parent;
475
476 err = ovl_copy_up(parent);
477 if (err)
478 return err;
479
480 old_cred = ovl_override_creds(dentry->d_sb);
481
482 /*
483 * When linking a file with copy up origin into a new parent, mark the
484 * new parent dir "impure".
485 */
486 if (origin) {
487 err = ovl_set_impure(parent, ovl_dentry_upper(parent));
488 if (err)
489 goto out_revert_creds;
490 }
491
492 err = -ENOMEM;
493 override_cred = prepare_creds();
494 if (override_cred) {
495 override_cred->fsuid = inode->i_uid;
496 override_cred->fsgid = inode->i_gid;
497 if (!hardlink) {
498 err = security_dentry_create_files_as(dentry,
499 attr->mode, &dentry->d_name,
500 old_cred ? old_cred : current_cred(),
501 override_cred);
502 if (err) {
503 put_cred(override_cred);
504 goto out_revert_creds;
505 }
506 }
507 hold_cred = override_creds(override_cred);
508 put_cred(override_cred);
509
510 if (!ovl_dentry_is_whiteout(dentry))
511 err = ovl_create_upper(dentry, inode, attr,
512 hardlink);
513 else
514 err = ovl_create_over_whiteout(dentry, inode, attr,
515 hardlink);
516 }
517 out_revert_creds:
518 ovl_revert_creds(old_cred ?: hold_cred);
519 if (old_cred && hold_cred)
520 put_cred(hold_cred);
521 if (!err) {
522 struct inode *realinode = d_inode(ovl_dentry_upper(dentry));
523
524 WARN_ON(inode->i_mode != realinode->i_mode);
525 WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
526 WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
527 }
528 return err;
529 }
530
ovl_create_object(struct dentry * dentry,int mode,dev_t rdev,const char * link)531 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
532 const char *link)
533 {
534 int err;
535 struct inode *inode;
536 struct cattr attr = {
537 .rdev = rdev,
538 .link = link,
539 };
540
541 err = ovl_want_write(dentry);
542 if (err)
543 goto out;
544
545 err = -ENOMEM;
546 inode = ovl_new_inode(dentry->d_sb, mode, rdev);
547 if (!inode)
548 goto out_drop_write;
549
550 inode_init_owner(inode, dentry->d_parent->d_inode, mode);
551 attr.mode = inode->i_mode;
552
553 err = ovl_create_or_link(dentry, inode, &attr, NULL, false);
554 if (err)
555 iput(inode);
556
557 out_drop_write:
558 ovl_drop_write(dentry);
559 out:
560 return err;
561 }
562
ovl_create(struct inode * dir,struct dentry * dentry,umode_t mode,bool excl)563 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
564 bool excl)
565 {
566 return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
567 }
568
ovl_mkdir(struct inode * dir,struct dentry * dentry,umode_t mode)569 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
570 {
571 return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
572 }
573
ovl_mknod(struct inode * dir,struct dentry * dentry,umode_t mode,dev_t rdev)574 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
575 dev_t rdev)
576 {
577 /* Don't allow creation of "whiteout" on overlay */
578 if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
579 return -EPERM;
580
581 return ovl_create_object(dentry, mode, rdev, NULL);
582 }
583
ovl_symlink(struct inode * dir,struct dentry * dentry,const char * link)584 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
585 const char *link)
586 {
587 return ovl_create_object(dentry, S_IFLNK, 0, link);
588 }
589
ovl_link(struct dentry * old,struct inode * newdir,struct dentry * new)590 static int ovl_link(struct dentry *old, struct inode *newdir,
591 struct dentry *new)
592 {
593 int err;
594 bool locked = false;
595 struct inode *inode;
596
597 err = ovl_want_write(old);
598 if (err)
599 goto out;
600
601 err = ovl_copy_up(old);
602 if (err)
603 goto out_drop_write;
604
605 err = ovl_copy_up(new->d_parent);
606 if (err)
607 goto out_drop_write;
608
609
610 err = ovl_nlink_start(old, &locked);
611 if (err)
612 goto out_drop_write;
613
614 inode = d_inode(old);
615 ihold(inode);
616
617 err = ovl_create_or_link(new, inode, NULL, ovl_dentry_upper(old),
618 ovl_type_origin(old));
619 if (err)
620 iput(inode);
621
622 ovl_nlink_end(old, locked);
623 out_drop_write:
624 ovl_drop_write(old);
625 out:
626 return err;
627 }
628
ovl_matches_upper(struct dentry * dentry,struct dentry * upper)629 static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper)
630 {
631 return d_inode(ovl_dentry_upper(dentry)) == d_inode(upper);
632 }
633
ovl_remove_and_whiteout(struct dentry * dentry,bool is_dir)634 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
635 {
636 struct dentry *workdir = ovl_workdir(dentry);
637 struct inode *wdir = workdir->d_inode;
638 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
639 struct inode *udir = upperdir->d_inode;
640 struct dentry *whiteout;
641 struct dentry *upper;
642 struct dentry *opaquedir = NULL;
643 int err;
644 int flags = 0;
645
646 if (WARN_ON(!workdir))
647 return -EROFS;
648
649 if (is_dir) {
650 opaquedir = ovl_check_empty_and_clear(dentry);
651 err = PTR_ERR(opaquedir);
652 if (IS_ERR(opaquedir))
653 goto out;
654 }
655
656 err = ovl_lock_rename_workdir(workdir, upperdir);
657 if (err)
658 goto out_dput;
659
660 upper = lookup_one_len(dentry->d_name.name, upperdir,
661 dentry->d_name.len);
662 err = PTR_ERR(upper);
663 if (IS_ERR(upper))
664 goto out_unlock;
665
666 err = -ESTALE;
667 if ((opaquedir && upper != opaquedir) ||
668 (!opaquedir && ovl_dentry_upper(dentry) &&
669 !ovl_matches_upper(dentry, upper))) {
670 goto out_dput_upper;
671 }
672
673 whiteout = ovl_whiteout(workdir, dentry);
674 err = PTR_ERR(whiteout);
675 if (IS_ERR(whiteout))
676 goto out_dput_upper;
677
678 if (d_is_dir(upper))
679 flags = RENAME_EXCHANGE;
680
681 err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
682 if (err)
683 goto kill_whiteout;
684 if (flags)
685 ovl_cleanup(wdir, upper);
686
687 ovl_dentry_version_inc(dentry->d_parent, true);
688 out_d_drop:
689 d_drop(dentry);
690 dput(whiteout);
691 out_dput_upper:
692 dput(upper);
693 out_unlock:
694 unlock_rename(workdir, upperdir);
695 out_dput:
696 dput(opaquedir);
697 out:
698 return err;
699
700 kill_whiteout:
701 ovl_cleanup(wdir, whiteout);
702 goto out_d_drop;
703 }
704
ovl_remove_upper(struct dentry * dentry,bool is_dir)705 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
706 {
707 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
708 struct inode *dir = upperdir->d_inode;
709 struct dentry *upper;
710 struct dentry *opaquedir = NULL;
711 int err;
712
713 /* Redirect dir can be !ovl_lower_positive && OVL_TYPE_MERGE */
714 if (is_dir && ovl_dentry_get_redirect(dentry)) {
715 opaquedir = ovl_check_empty_and_clear(dentry);
716 err = PTR_ERR(opaquedir);
717 if (IS_ERR(opaquedir))
718 goto out;
719 }
720
721 inode_lock_nested(dir, I_MUTEX_PARENT);
722 upper = lookup_one_len(dentry->d_name.name, upperdir,
723 dentry->d_name.len);
724 err = PTR_ERR(upper);
725 if (IS_ERR(upper))
726 goto out_unlock;
727
728 err = -ESTALE;
729 if ((opaquedir && upper != opaquedir) ||
730 (!opaquedir && !ovl_matches_upper(dentry, upper)))
731 goto out_dput_upper;
732
733 if (is_dir)
734 err = vfs_rmdir(dir, upper);
735 else
736 err = vfs_unlink(dir, upper, NULL);
737 ovl_dentry_version_inc(dentry->d_parent, ovl_type_origin(dentry));
738
739 /*
740 * Keeping this dentry hashed would mean having to release
741 * upperpath/lowerpath, which could only be done if we are the
742 * sole user of this dentry. Too tricky... Just unhash for
743 * now.
744 */
745 if (!err)
746 d_drop(dentry);
747 out_dput_upper:
748 dput(upper);
749 out_unlock:
750 inode_unlock(dir);
751 dput(opaquedir);
752 out:
753 return err;
754 }
755
ovl_do_remove(struct dentry * dentry,bool is_dir)756 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
757 {
758 int err;
759 bool locked = false;
760 const struct cred *old_cred;
761
762 err = ovl_want_write(dentry);
763 if (err)
764 goto out;
765
766 err = ovl_copy_up(dentry->d_parent);
767 if (err)
768 goto out_drop_write;
769
770 err = ovl_nlink_start(dentry, &locked);
771 if (err)
772 goto out_drop_write;
773
774 old_cred = ovl_override_creds(dentry->d_sb);
775 if (!ovl_lower_positive(dentry))
776 err = ovl_remove_upper(dentry, is_dir);
777 else
778 err = ovl_remove_and_whiteout(dentry, is_dir);
779 ovl_revert_creds(old_cred);
780 if (!err) {
781 if (is_dir)
782 clear_nlink(dentry->d_inode);
783 else
784 drop_nlink(dentry->d_inode);
785 }
786 ovl_nlink_end(dentry, locked);
787 out_drop_write:
788 ovl_drop_write(dentry);
789 out:
790 return err;
791 }
792
ovl_unlink(struct inode * dir,struct dentry * dentry)793 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
794 {
795 return ovl_do_remove(dentry, false);
796 }
797
ovl_rmdir(struct inode * dir,struct dentry * dentry)798 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
799 {
800 return ovl_do_remove(dentry, true);
801 }
802
ovl_type_merge_or_lower(struct dentry * dentry)803 static bool ovl_type_merge_or_lower(struct dentry *dentry)
804 {
805 enum ovl_path_type type = ovl_path_type(dentry);
806
807 return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type);
808 }
809
ovl_can_move(struct dentry * dentry)810 static bool ovl_can_move(struct dentry *dentry)
811 {
812 return ovl_redirect_dir(dentry->d_sb) ||
813 !d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry);
814 }
815
ovl_get_redirect(struct dentry * dentry,bool samedir)816 static char *ovl_get_redirect(struct dentry *dentry, bool samedir)
817 {
818 char *buf, *ret;
819 struct dentry *d, *tmp;
820 int buflen = ovl_redirect_max + 1;
821
822 if (samedir) {
823 ret = kstrndup(dentry->d_name.name, dentry->d_name.len,
824 GFP_KERNEL);
825 goto out;
826 }
827
828 buf = ret = kmalloc(buflen, GFP_KERNEL);
829 if (!buf)
830 goto out;
831
832 buflen--;
833 buf[buflen] = '\0';
834 for (d = dget(dentry); !IS_ROOT(d);) {
835 const char *name;
836 int thislen;
837
838 spin_lock(&d->d_lock);
839 name = ovl_dentry_get_redirect(d);
840 if (name) {
841 thislen = strlen(name);
842 } else {
843 name = d->d_name.name;
844 thislen = d->d_name.len;
845 }
846
847 /* If path is too long, fall back to userspace move */
848 if (thislen + (name[0] != '/') > buflen) {
849 ret = ERR_PTR(-EXDEV);
850 spin_unlock(&d->d_lock);
851 goto out_put;
852 }
853
854 buflen -= thislen;
855 memcpy(&buf[buflen], name, thislen);
856 tmp = dget_dlock(d->d_parent);
857 spin_unlock(&d->d_lock);
858
859 dput(d);
860 d = tmp;
861
862 /* Absolute redirect: finished */
863 if (buf[buflen] == '/')
864 break;
865 buflen--;
866 buf[buflen] = '/';
867 }
868 ret = kstrdup(&buf[buflen], GFP_KERNEL);
869 out_put:
870 dput(d);
871 kfree(buf);
872 out:
873 return ret ? ret : ERR_PTR(-ENOMEM);
874 }
875
ovl_set_redirect(struct dentry * dentry,bool samedir)876 static int ovl_set_redirect(struct dentry *dentry, bool samedir)
877 {
878 int err;
879 const char *redirect = ovl_dentry_get_redirect(dentry);
880
881 if (redirect && (samedir || redirect[0] == '/'))
882 return 0;
883
884 redirect = ovl_get_redirect(dentry, samedir);
885 if (IS_ERR(redirect))
886 return PTR_ERR(redirect);
887
888 err = ovl_check_setxattr(dentry, ovl_dentry_upper(dentry),
889 OVL_XATTR_REDIRECT,
890 redirect, strlen(redirect), -EXDEV);
891 if (!err) {
892 spin_lock(&dentry->d_lock);
893 ovl_dentry_set_redirect(dentry, redirect);
894 spin_unlock(&dentry->d_lock);
895 } else {
896 kfree(redirect);
897 pr_warn_ratelimited("overlay: failed to set redirect (%i)\n", err);
898 /* Fall back to userspace copy-up */
899 err = -EXDEV;
900 }
901 return err;
902 }
903
ovl_rename(struct inode * olddir,struct dentry * old,struct inode * newdir,struct dentry * new,unsigned int flags)904 static int ovl_rename(struct inode *olddir, struct dentry *old,
905 struct inode *newdir, struct dentry *new,
906 unsigned int flags)
907 {
908 int err;
909 bool locked = false;
910 struct dentry *old_upperdir;
911 struct dentry *new_upperdir;
912 struct dentry *olddentry;
913 struct dentry *newdentry;
914 struct dentry *trap;
915 bool old_opaque;
916 bool new_opaque;
917 bool cleanup_whiteout = false;
918 bool overwrite = !(flags & RENAME_EXCHANGE);
919 bool is_dir = d_is_dir(old);
920 bool new_is_dir = d_is_dir(new);
921 bool samedir = olddir == newdir;
922 struct dentry *opaquedir = NULL;
923 const struct cred *old_cred = NULL;
924
925 err = -EINVAL;
926 if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
927 goto out;
928
929 flags &= ~RENAME_NOREPLACE;
930
931 /* Don't copy up directory trees */
932 err = -EXDEV;
933 if (!ovl_can_move(old))
934 goto out;
935 if (!overwrite && !ovl_can_move(new))
936 goto out;
937
938 err = ovl_want_write(old);
939 if (err)
940 goto out;
941
942 err = ovl_copy_up(old);
943 if (err)
944 goto out_drop_write;
945
946 err = ovl_copy_up(new->d_parent);
947 if (err)
948 goto out_drop_write;
949 if (!overwrite) {
950 err = ovl_copy_up(new);
951 if (err)
952 goto out_drop_write;
953 } else {
954 err = ovl_nlink_start(new, &locked);
955 if (err)
956 goto out_drop_write;
957 }
958
959 old_cred = ovl_override_creds(old->d_sb);
960
961 if (overwrite && new_is_dir && ovl_type_merge_or_lower(new)) {
962 opaquedir = ovl_check_empty_and_clear(new);
963 err = PTR_ERR(opaquedir);
964 if (IS_ERR(opaquedir)) {
965 opaquedir = NULL;
966 goto out_revert_creds;
967 }
968 }
969
970 if (overwrite) {
971 if (ovl_lower_positive(old)) {
972 if (!ovl_dentry_is_whiteout(new)) {
973 /* Whiteout source */
974 flags |= RENAME_WHITEOUT;
975 } else {
976 /* Switch whiteouts */
977 flags |= RENAME_EXCHANGE;
978 }
979 } else if (is_dir && ovl_dentry_is_whiteout(new)) {
980 flags |= RENAME_EXCHANGE;
981 cleanup_whiteout = true;
982 }
983 }
984
985 old_upperdir = ovl_dentry_upper(old->d_parent);
986 new_upperdir = ovl_dentry_upper(new->d_parent);
987
988 if (!samedir) {
989 /*
990 * When moving a merge dir or non-dir with copy up origin into
991 * a new parent, we are marking the new parent dir "impure".
992 * When ovl_iterate() iterates an "impure" upper dir, it will
993 * lookup the origin inodes of the entries to fill d_ino.
994 */
995 if (ovl_type_origin(old)) {
996 err = ovl_set_impure(new->d_parent, new_upperdir);
997 if (err)
998 goto out_revert_creds;
999 }
1000 if (!overwrite && ovl_type_origin(new)) {
1001 err = ovl_set_impure(old->d_parent, old_upperdir);
1002 if (err)
1003 goto out_revert_creds;
1004 }
1005 }
1006
1007 trap = lock_rename(new_upperdir, old_upperdir);
1008
1009 olddentry = lookup_one_len(old->d_name.name, old_upperdir,
1010 old->d_name.len);
1011 err = PTR_ERR(olddentry);
1012 if (IS_ERR(olddentry))
1013 goto out_unlock;
1014
1015 err = -ESTALE;
1016 if (!ovl_matches_upper(old, olddentry))
1017 goto out_dput_old;
1018
1019 newdentry = lookup_one_len(new->d_name.name, new_upperdir,
1020 new->d_name.len);
1021 err = PTR_ERR(newdentry);
1022 if (IS_ERR(newdentry))
1023 goto out_dput_old;
1024
1025 old_opaque = ovl_dentry_is_opaque(old);
1026 new_opaque = ovl_dentry_is_opaque(new);
1027
1028 err = -ESTALE;
1029 if (d_inode(new) && ovl_dentry_upper(new)) {
1030 if (opaquedir) {
1031 if (newdentry != opaquedir)
1032 goto out_dput;
1033 } else {
1034 if (!ovl_matches_upper(new, newdentry))
1035 goto out_dput;
1036 }
1037 } else {
1038 if (!d_is_negative(newdentry) &&
1039 (!new_opaque || !ovl_is_whiteout(newdentry)))
1040 goto out_dput;
1041 }
1042
1043 if (olddentry == trap)
1044 goto out_dput;
1045 if (newdentry == trap)
1046 goto out_dput;
1047
1048 if (olddentry->d_inode == newdentry->d_inode)
1049 goto out_dput;
1050
1051 err = 0;
1052 if (is_dir) {
1053 if (ovl_type_merge_or_lower(old))
1054 err = ovl_set_redirect(old, samedir);
1055 else if (!old_opaque && ovl_type_merge(new->d_parent))
1056 err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
1057 if (err)
1058 goto out_dput;
1059 }
1060 if (!overwrite && new_is_dir) {
1061 if (ovl_type_merge_or_lower(new))
1062 err = ovl_set_redirect(new, samedir);
1063 else if (!new_opaque && ovl_type_merge(old->d_parent))
1064 err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
1065 if (err)
1066 goto out_dput;
1067 }
1068
1069 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
1070 new_upperdir->d_inode, newdentry, flags);
1071 if (err)
1072 goto out_dput;
1073
1074 if (cleanup_whiteout)
1075 ovl_cleanup(old_upperdir->d_inode, newdentry);
1076
1077 if (overwrite && d_inode(new)) {
1078 if (new_is_dir)
1079 clear_nlink(d_inode(new));
1080 else
1081 drop_nlink(d_inode(new));
1082 }
1083
1084 ovl_dentry_version_inc(old->d_parent,
1085 !overwrite && ovl_type_origin(new));
1086 ovl_dentry_version_inc(new->d_parent, ovl_type_origin(old));
1087
1088 out_dput:
1089 dput(newdentry);
1090 out_dput_old:
1091 dput(olddentry);
1092 out_unlock:
1093 unlock_rename(new_upperdir, old_upperdir);
1094 out_revert_creds:
1095 ovl_revert_creds(old_cred);
1096 ovl_nlink_end(new, locked);
1097 out_drop_write:
1098 ovl_drop_write(old);
1099 out:
1100 dput(opaquedir);
1101 return err;
1102 }
1103
1104 const struct inode_operations ovl_dir_inode_operations = {
1105 .lookup = ovl_lookup,
1106 .mkdir = ovl_mkdir,
1107 .symlink = ovl_symlink,
1108 .unlink = ovl_unlink,
1109 .rmdir = ovl_rmdir,
1110 .rename = ovl_rename,
1111 .link = ovl_link,
1112 .setattr = ovl_setattr,
1113 .create = ovl_create,
1114 .mknod = ovl_mknod,
1115 .permission = ovl_permission,
1116 .getattr = ovl_getattr,
1117 .listxattr = ovl_listxattr,
1118 .get_acl = ovl_get_acl,
1119 .update_time = ovl_update_time,
1120 };
1121