1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2011 Novell Inc.
4 * Copyright (C) 2016 Red Hat, Inc.
5 */
6
7 #include <linux/fs.h>
8 #include <linux/mount.h>
9 #include <linux/slab.h>
10 #include <linux/cred.h>
11 #include <linux/xattr.h>
12 #include <linux/exportfs.h>
13 #include <linux/file.h>
14 #include <linux/fileattr.h>
15 #include <linux/uuid.h>
16 #include <linux/namei.h>
17 #include <linux/ratelimit.h>
18 #include "overlayfs.h"
19
20 /* Get write access to upper mnt - may fail if upper sb was remounted ro */
21 int ovl_get_write_access(struct dentry *dentry)
22 {
23 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
24 return mnt_get_write_access(ovl_upper_mnt(ofs));
25 }
26
27 /* Get write access to upper sb - may block if upper sb is frozen */
28 void ovl_start_write(struct dentry *dentry)
29 {
30 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
31 sb_start_write(ovl_upper_mnt(ofs)->mnt_sb);
32 }
33
34 int ovl_want_write(struct dentry *dentry)
35 {
36 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
37 return mnt_want_write(ovl_upper_mnt(ofs));
38 }
39
40 void ovl_put_write_access(struct dentry *dentry)
41 {
42 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
43 mnt_put_write_access(ovl_upper_mnt(ofs));
44 }
45
46 void ovl_end_write(struct dentry *dentry)
47 {
48 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
49 sb_end_write(ovl_upper_mnt(ofs)->mnt_sb);
50 }
51
52 void ovl_drop_write(struct dentry *dentry)
53 {
54 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
55 mnt_drop_write(ovl_upper_mnt(ofs));
56 }
57
58 struct dentry *ovl_workdir(struct dentry *dentry)
59 {
60 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
61 return ofs->workdir;
62 }
63
64 const struct cred *ovl_override_creds(struct super_block *sb)
65 {
66 struct ovl_fs *ofs = OVL_FS(sb);
67
68 return override_creds(ofs->creator_cred);
69 }
70
71 /*
72 * Check if underlying fs supports file handles and try to determine encoding
73 * type, in order to deduce maximum inode number used by fs.
74 *
75 * Return 0 if file handles are not supported.
76 * Return 1 (FILEID_INO32_GEN) if fs uses the default 32bit inode encoding.
77 * Return -1 if fs uses a non default encoding with unknown inode size.
78 */
79 int ovl_can_decode_fh(struct super_block *sb)
80 {
81 if (!capable(CAP_DAC_READ_SEARCH))
82 return 0;
83
84 if (!exportfs_can_decode_fh(sb->s_export_op))
85 return 0;
86
87 return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN;
88 }
89
90 struct dentry *ovl_indexdir(struct super_block *sb)
91 {
92 struct ovl_fs *ofs = OVL_FS(sb);
93
94 return ofs->config.index ? ofs->workdir : NULL;
95 }
96
97 /* Index all files on copy up. For now only enabled for NFS export */
98 bool ovl_index_all(struct super_block *sb)
99 {
100 struct ovl_fs *ofs = OVL_FS(sb);
101
102 return ofs->config.nfs_export && ofs->config.index;
103 }
104
105 /* Verify lower origin on lookup. For now only enabled for NFS export */
106 bool ovl_verify_lower(struct super_block *sb)
107 {
108 struct ovl_fs *ofs = OVL_FS(sb);
109
110 return ofs->config.nfs_export && ofs->config.index;
111 }
112
113 struct ovl_path *ovl_stack_alloc(unsigned int n)
114 {
115 return kcalloc(n, sizeof(struct ovl_path), GFP_KERNEL);
116 }
117
118 void ovl_stack_cpy(struct ovl_path *dst, struct ovl_path *src, unsigned int n)
119 {
120 unsigned int i;
121
122 memcpy(dst, src, sizeof(struct ovl_path) * n);
123 for (i = 0; i < n; i++)
124 dget(src[i].dentry);
125 }
126
127 void ovl_stack_put(struct ovl_path *stack, unsigned int n)
128 {
129 unsigned int i;
130
131 for (i = 0; stack && i < n; i++)
132 dput(stack[i].dentry);
133 }
134
135 void ovl_stack_free(struct ovl_path *stack, unsigned int n)
136 {
137 ovl_stack_put(stack, n);
138 kfree(stack);
139 }
140
141 struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
142 {
143 size_t size = offsetof(struct ovl_entry, __lowerstack[numlower]);
144 struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
145
146 if (oe)
147 oe->__numlower = numlower;
148
149 return oe;
150 }
151
152 void ovl_free_entry(struct ovl_entry *oe)
153 {
154 ovl_stack_put(ovl_lowerstack(oe), ovl_numlower(oe));
155 kfree(oe);
156 }
157
158 #define OVL_D_REVALIDATE (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE)
159
160 bool ovl_dentry_remote(struct dentry *dentry)
161 {
162 return dentry->d_flags & OVL_D_REVALIDATE;
163 }
164
165 void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *realdentry)
166 {
167 if (!ovl_dentry_remote(realdentry))
168 return;
169
170 spin_lock(&dentry->d_lock);
171 dentry->d_flags |= realdentry->d_flags & OVL_D_REVALIDATE;
172 spin_unlock(&dentry->d_lock);
173 }
174
175 void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry,
176 struct ovl_entry *oe)
177 {
178 return ovl_dentry_init_flags(dentry, upperdentry, oe, OVL_D_REVALIDATE);
179 }
180
181 void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
182 struct ovl_entry *oe, unsigned int mask)
183 {
184 struct ovl_path *lowerstack = ovl_lowerstack(oe);
185 unsigned int i, flags = 0;
186
187 if (upperdentry)
188 flags |= upperdentry->d_flags;
189 for (i = 0; i < ovl_numlower(oe) && lowerstack[i].dentry; i++)
190 flags |= lowerstack[i].dentry->d_flags;
191
192 spin_lock(&dentry->d_lock);
193 dentry->d_flags &= ~mask;
194 dentry->d_flags |= flags & mask;
195 spin_unlock(&dentry->d_lock);
196 }
197
198 bool ovl_dentry_weird(struct dentry *dentry)
199 {
200 return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
201 DCACHE_MANAGE_TRANSIT |
202 DCACHE_OP_HASH |
203 DCACHE_OP_COMPARE);
204 }
205
206 enum ovl_path_type ovl_path_type(struct dentry *dentry)
207 {
208 struct ovl_entry *oe = OVL_E(dentry);
209 enum ovl_path_type type = 0;
210
211 if (ovl_dentry_upper(dentry)) {
212 type = __OVL_PATH_UPPER;
213
214 /*
215 * Non-dir dentry can hold lower dentry of its copy up origin.
216 */
217 if (ovl_numlower(oe)) {
218 if (ovl_test_flag(OVL_CONST_INO, d_inode(dentry)))
219 type |= __OVL_PATH_ORIGIN;
220 if (d_is_dir(dentry) ||
221 !ovl_has_upperdata(d_inode(dentry)))
222 type |= __OVL_PATH_MERGE;
223 }
224 } else {
225 if (ovl_numlower(oe) > 1)
226 type |= __OVL_PATH_MERGE;
227 }
228 return type;
229 }
230
231 void ovl_path_upper(struct dentry *dentry, struct path *path)
232 {
233 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
234
235 path->mnt = ovl_upper_mnt(ofs);
236 path->dentry = ovl_dentry_upper(dentry);
237 }
238
239 void ovl_path_lower(struct dentry *dentry, struct path *path)
240 {
241 struct ovl_entry *oe = OVL_E(dentry);
242 struct ovl_path *lowerpath = ovl_lowerstack(oe);
243
244 if (ovl_numlower(oe)) {
245 path->mnt = lowerpath->layer->mnt;
246 path->dentry = lowerpath->dentry;
247 } else {
248 *path = (struct path) { };
249 }
250 }
251
252 void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
253 {
254 struct ovl_entry *oe = OVL_E(dentry);
255 struct ovl_path *lowerdata = ovl_lowerdata(oe);
256 struct dentry *lowerdata_dentry = ovl_lowerdata_dentry(oe);
257
258 if (lowerdata_dentry) {
259 path->dentry = lowerdata_dentry;
260 /*
261 * Pairs with smp_wmb() in ovl_dentry_set_lowerdata().
262 * Make sure that if lowerdata->dentry is visible, then
263 * datapath->layer is visible as well.
264 */
265 smp_rmb();
266 path->mnt = READ_ONCE(lowerdata->layer)->mnt;
267 } else {
268 *path = (struct path) { };
269 }
270 }
271
272 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
273 {
274 enum ovl_path_type type = ovl_path_type(dentry);
275
276 if (!OVL_TYPE_UPPER(type))
277 ovl_path_lower(dentry, path);
278 else
279 ovl_path_upper(dentry, path);
280
281 return type;
282 }
283
284 enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path)
285 {
286 enum ovl_path_type type = ovl_path_type(dentry);
287
288 WARN_ON_ONCE(d_is_dir(dentry));
289
290 if (!OVL_TYPE_UPPER(type) || OVL_TYPE_MERGE(type))
291 ovl_path_lowerdata(dentry, path);
292 else
293 ovl_path_upper(dentry, path);
294
295 return type;
296 }
297
298 struct dentry *ovl_dentry_upper(struct dentry *dentry)
299 {
300 return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
301 }
302
303 struct dentry *ovl_dentry_lower(struct dentry *dentry)
304 {
305 struct ovl_entry *oe = OVL_E(dentry);
306
307 return ovl_numlower(oe) ? ovl_lowerstack(oe)->dentry : NULL;
308 }
309
310 const struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
311 {
312 struct ovl_entry *oe = OVL_E(dentry);
313
314 return ovl_numlower(oe) ? ovl_lowerstack(oe)->layer : NULL;
315 }
316
317 /*
318 * ovl_dentry_lower() could return either a data dentry or metacopy dentry
319 * depending on what is stored in lowerstack[0]. At times we need to find
320 * lower dentry which has data (and not metacopy dentry). This helper
321 * returns the lower data dentry.
322 */
323 struct dentry *ovl_dentry_lowerdata(struct dentry *dentry)
324 {
325 return ovl_lowerdata_dentry(OVL_E(dentry));
326 }
327
328 int ovl_dentry_set_lowerdata(struct dentry *dentry, struct ovl_path *datapath)
329 {
330 struct ovl_entry *oe = OVL_E(dentry);
331 struct ovl_path *lowerdata = ovl_lowerdata(oe);
332 struct dentry *datadentry = datapath->dentry;
333
334 if (WARN_ON_ONCE(ovl_numlower(oe) <= 1))
335 return -EIO;
336
337 WRITE_ONCE(lowerdata->layer, datapath->layer);
338 /*
339 * Pairs with smp_rmb() in ovl_path_lowerdata().
340 * Make sure that if lowerdata->dentry is visible, then
341 * lowerdata->layer is visible as well.
342 */
343 smp_wmb();
344 WRITE_ONCE(lowerdata->dentry, dget(datadentry));
345
346 ovl_dentry_update_reval(dentry, datadentry);
347
348 return 0;
349 }
350
351 struct dentry *ovl_dentry_real(struct dentry *dentry)
352 {
353 return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
354 }
355
356 struct dentry *ovl_i_dentry_upper(struct inode *inode)
357 {
358 return ovl_upperdentry_dereference(OVL_I(inode));
359 }
360
361 struct inode *ovl_i_path_real(struct inode *inode, struct path *path)
362 {
363 struct ovl_path *lowerpath = ovl_lowerpath(OVL_I_E(inode));
364
365 path->dentry = ovl_i_dentry_upper(inode);
366 if (!path->dentry) {
367 path->dentry = lowerpath->dentry;
368 path->mnt = lowerpath->layer->mnt;
369 } else {
370 path->mnt = ovl_upper_mnt(OVL_FS(inode->i_sb));
371 }
372
373 return path->dentry ? d_inode_rcu(path->dentry) : NULL;
374 }
375
376 struct inode *ovl_inode_upper(struct inode *inode)
377 {
378 struct dentry *upperdentry = ovl_i_dentry_upper(inode);
379
380 return upperdentry ? d_inode(upperdentry) : NULL;
381 }
382
383 struct inode *ovl_inode_lower(struct inode *inode)
384 {
385 struct ovl_path *lowerpath = ovl_lowerpath(OVL_I_E(inode));
386
387 return lowerpath ? d_inode(lowerpath->dentry) : NULL;
388 }
389
390 struct inode *ovl_inode_real(struct inode *inode)
391 {
392 return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
393 }
394
395 /* Return inode which contains lower data. Do not return metacopy */
396 struct inode *ovl_inode_lowerdata(struct inode *inode)
397 {
398 struct dentry *lowerdata = ovl_lowerdata_dentry(OVL_I_E(inode));
399
400 if (WARN_ON(!S_ISREG(inode->i_mode)))
401 return NULL;
402
403 return lowerdata ? d_inode(lowerdata) : NULL;
404 }
405
406 /* Return real inode which contains data. Does not return metacopy inode */
407 struct inode *ovl_inode_realdata(struct inode *inode)
408 {
409 struct inode *upperinode;
410
411 upperinode = ovl_inode_upper(inode);
412 if (upperinode && ovl_has_upperdata(inode))
413 return upperinode;
414
415 return ovl_inode_lowerdata(inode);
416 }
417
418 const char *ovl_lowerdata_redirect(struct inode *inode)
419 {
420 return inode && S_ISREG(inode->i_mode) ?
421 OVL_I(inode)->lowerdata_redirect : NULL;
422 }
423
424 struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
425 {
426 return inode && S_ISDIR(inode->i_mode) ? OVL_I(inode)->cache : NULL;
427 }
428
429 void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache)
430 {
431 OVL_I(inode)->cache = cache;
432 }
433
434 void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry)
435 {
436 set_bit(flag, OVL_E_FLAGS(dentry));
437 }
438
439 void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry)
440 {
441 clear_bit(flag, OVL_E_FLAGS(dentry));
442 }
443
444 bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry)
445 {
446 return test_bit(flag, OVL_E_FLAGS(dentry));
447 }
448
449 bool ovl_dentry_is_opaque(struct dentry *dentry)
450 {
451 return ovl_dentry_test_flag(OVL_E_OPAQUE, dentry);
452 }
453
454 bool ovl_dentry_is_whiteout(struct dentry *dentry)
455 {
456 return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
457 }
458
459 void ovl_dentry_set_opaque(struct dentry *dentry)
460 {
461 ovl_dentry_set_flag(OVL_E_OPAQUE, dentry);
462 }
463
464 bool ovl_dentry_has_xwhiteouts(struct dentry *dentry)
465 {
466 return ovl_dentry_test_flag(OVL_E_XWHITEOUTS, dentry);
467 }
468
469 void ovl_dentry_set_xwhiteouts(struct dentry *dentry)
470 {
471 ovl_dentry_set_flag(OVL_E_XWHITEOUTS, dentry);
472 }
473
474 /*
475 * ovl_layer_set_xwhiteouts() is called before adding the overlay dir
476 * dentry to dcache, while readdir of that same directory happens after
477 * the overlay dir dentry is in dcache, so if some cpu observes that
478 * ovl_dentry_is_xwhiteouts(), it will also observe layer->has_xwhiteouts
479 * for the layers where xwhiteouts marker was found in that merge dir.
480 */
481 void ovl_layer_set_xwhiteouts(struct ovl_fs *ofs,
482 const struct ovl_layer *layer)
483 {
484 if (layer->has_xwhiteouts)
485 return;
486
487 /* Write once to read-mostly layer properties */
488 ofs->layers[layer->idx].has_xwhiteouts = true;
489 }
490
491 /*
492 * For hard links and decoded file handles, it's possible for ovl_dentry_upper()
493 * to return positive, while there's no actual upper alias for the inode.
494 * Copy up code needs to know about the existence of the upper alias, so it
495 * can't use ovl_dentry_upper().
496 */
497 bool ovl_dentry_has_upper_alias(struct dentry *dentry)
498 {
499 return ovl_dentry_test_flag(OVL_E_UPPER_ALIAS, dentry);
500 }
501
502 void ovl_dentry_set_upper_alias(struct dentry *dentry)
503 {
504 ovl_dentry_set_flag(OVL_E_UPPER_ALIAS, dentry);
505 }
506
507 static bool ovl_should_check_upperdata(struct inode *inode)
508 {
509 if (!S_ISREG(inode->i_mode))
510 return false;
511
512 if (!ovl_inode_lower(inode))
513 return false;
514
515 return true;
516 }
517
518 bool ovl_has_upperdata(struct inode *inode)
519 {
520 if (!ovl_should_check_upperdata(inode))
521 return true;
522
523 if (!ovl_test_flag(OVL_UPPERDATA, inode))
524 return false;
525 /*
526 * Pairs with smp_wmb() in ovl_set_upperdata(). Main user of
527 * ovl_has_upperdata() is ovl_copy_up_meta_inode_data(). Make sure
528 * if setting of OVL_UPPERDATA is visible, then effects of writes
529 * before that are visible too.
530 */
531 smp_rmb();
532 return true;
533 }
534
535 void ovl_set_upperdata(struct inode *inode)
536 {
537 /*
538 * Pairs with smp_rmb() in ovl_has_upperdata(). Make sure
539 * if OVL_UPPERDATA flag is visible, then effects of write operations
540 * before it are visible as well.
541 */
542 smp_wmb();
543 ovl_set_flag(OVL_UPPERDATA, inode);
544 }
545
546 /* Caller should hold ovl_inode->lock */
547 bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags)
548 {
549 if (!ovl_open_flags_need_copy_up(flags))
550 return false;
551
552 return !ovl_test_flag(OVL_UPPERDATA, d_inode(dentry));
553 }
554
555 bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags)
556 {
557 if (!ovl_open_flags_need_copy_up(flags))
558 return false;
559
560 return !ovl_has_upperdata(d_inode(dentry));
561 }
562
563 const char *ovl_dentry_get_redirect(struct dentry *dentry)
564 {
565 return OVL_I(d_inode(dentry))->redirect;
566 }
567
568 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
569 {
570 struct ovl_inode *oi = OVL_I(d_inode(dentry));
571
572 kfree(oi->redirect);
573 oi->redirect = redirect;
574 }
575
576 void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
577 {
578 struct inode *upperinode = d_inode(upperdentry);
579
580 WARN_ON(OVL_I(inode)->__upperdentry);
581
582 /*
583 * Make sure upperdentry is consistent before making it visible
584 */
585 smp_wmb();
586 OVL_I(inode)->__upperdentry = upperdentry;
587 if (inode_unhashed(inode)) {
588 inode->i_private = upperinode;
589 __insert_inode_hash(inode, (unsigned long) upperinode);
590 }
591 }
592
593 static void ovl_dir_version_inc(struct dentry *dentry, bool impurity)
594 {
595 struct inode *inode = d_inode(dentry);
596
597 WARN_ON(!inode_is_locked(inode));
598 WARN_ON(!d_is_dir(dentry));
599 /*
600 * Version is used by readdir code to keep cache consistent.
601 * For merge dirs (or dirs with origin) all changes need to be noted.
602 * For non-merge dirs, cache contains only impure entries (i.e. ones
603 * which have been copied up and have origins), so only need to note
604 * changes to impure entries.
605 */
606 if (!ovl_dir_is_real(inode) || impurity)
607 OVL_I(inode)->version++;
608 }
609
610 void ovl_dir_modified(struct dentry *dentry, bool impurity)
611 {
612 /* Copy mtime/ctime */
613 ovl_copyattr(d_inode(dentry));
614
615 ovl_dir_version_inc(dentry, impurity);
616 }
617
618 u64 ovl_inode_version_get(struct inode *inode)
619 {
620 WARN_ON(!inode_is_locked(inode));
621 return OVL_I(inode)->version;
622 }
623
624 bool ovl_is_whiteout(struct dentry *dentry)
625 {
626 struct inode *inode = dentry->d_inode;
627
628 return inode && IS_WHITEOUT(inode);
629 }
630
631 /*
632 * Use this over ovl_is_whiteout for upper and lower files, as it also
633 * handles overlay.whiteout xattr whiteout files.
634 */
635 bool ovl_path_is_whiteout(struct ovl_fs *ofs, const struct path *path)
636 {
637 return ovl_is_whiteout(path->dentry) ||
638 ovl_path_check_xwhiteout_xattr(ofs, path);
639 }
640
641 struct file *ovl_path_open(const struct path *path, int flags)
642 {
643 struct inode *inode = d_inode(path->dentry);
644 struct mnt_idmap *real_idmap = mnt_idmap(path->mnt);
645 int err, acc_mode;
646
647 if (flags & ~(O_ACCMODE | O_LARGEFILE))
648 BUG();
649
650 switch (flags & O_ACCMODE) {
651 case O_RDONLY:
652 acc_mode = MAY_READ;
653 break;
654 case O_WRONLY:
655 acc_mode = MAY_WRITE;
656 break;
657 default:
658 BUG();
659 }
660
661 err = inode_permission(real_idmap, inode, acc_mode | MAY_OPEN);
662 if (err)
663 return ERR_PTR(err);
664
665 /* O_NOATIME is an optimization, don't fail if not permitted */
666 if (inode_owner_or_capable(real_idmap, inode))
667 flags |= O_NOATIME;
668
669 return dentry_open(path, flags, current_cred());
670 }
671
672 /* Caller should hold ovl_inode->lock */
673 static bool ovl_already_copied_up_locked(struct dentry *dentry, int flags)
674 {
675 bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
676
677 if (ovl_dentry_upper(dentry) &&
678 (ovl_dentry_has_upper_alias(dentry) || disconnected) &&
679 !ovl_dentry_needs_data_copy_up_locked(dentry, flags))
680 return true;
681
682 return false;
683 }
684
685 bool ovl_already_copied_up(struct dentry *dentry, int flags)
686 {
687 bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
688
689 /*
690 * Check if copy-up has happened as well as for upper alias (in
691 * case of hard links) is there.
692 *
693 * Both checks are lockless:
694 * - false negatives: will recheck under oi->lock
695 * - false positives:
696 * + ovl_dentry_upper() uses memory barriers to ensure the
697 * upper dentry is up-to-date
698 * + ovl_dentry_has_upper_alias() relies on locking of
699 * upper parent i_rwsem to prevent reordering copy-up
700 * with rename.
701 */
702 if (ovl_dentry_upper(dentry) &&
703 (ovl_dentry_has_upper_alias(dentry) || disconnected) &&
704 !ovl_dentry_needs_data_copy_up(dentry, flags))
705 return true;
706
707 return false;
708 }
709
710 /*
711 * The copy up "transaction" keeps an elevated mnt write count on upper mnt,
712 * but leaves taking freeze protection on upper sb to lower level helpers.
713 */
714 int ovl_copy_up_start(struct dentry *dentry, int flags)
715 {
716 struct inode *inode = d_inode(dentry);
717 int err;
718
719 err = ovl_inode_lock_interruptible(inode);
720 if (err)
721 return err;
722
723 if (ovl_already_copied_up_locked(dentry, flags))
724 err = 1; /* Already copied up */
725 else
726 err = ovl_get_write_access(dentry);
727 if (err)
728 goto out_unlock;
729
730 return 0;
731
732 out_unlock:
733 ovl_inode_unlock(inode);
734 return err;
735 }
736
737 void ovl_copy_up_end(struct dentry *dentry)
738 {
739 ovl_put_write_access(dentry);
740 ovl_inode_unlock(d_inode(dentry));
741 }
742
743 bool ovl_path_check_origin_xattr(struct ovl_fs *ofs, const struct path *path)
744 {
745 int res;
746
747 res = ovl_path_getxattr(ofs, path, OVL_XATTR_ORIGIN, NULL, 0);
748
749 /* Zero size value means "copied up but origin unknown" */
750 if (res >= 0)
751 return true;
752
753 return false;
754 }
755
756 bool ovl_path_check_xwhiteout_xattr(struct ovl_fs *ofs, const struct path *path)
757 {
758 struct dentry *dentry = path->dentry;
759 int res;
760
761 /* xattr.whiteout must be a zero size regular file */
762 if (!d_is_reg(dentry) || i_size_read(d_inode(dentry)) != 0)
763 return false;
764
765 res = ovl_path_getxattr(ofs, path, OVL_XATTR_XWHITEOUT, NULL, 0);
766 return res >= 0;
767 }
768
769 /*
770 * Load persistent uuid from xattr into s_uuid if found, or store a new
771 * random generated value in s_uuid and in xattr.
772 */
773 bool ovl_init_uuid_xattr(struct super_block *sb, struct ovl_fs *ofs,
774 const struct path *upperpath)
775 {
776 bool set = false;
777 uuid_t uuid;
778 int res;
779
780 /* Try to load existing persistent uuid */
781 res = ovl_path_getxattr(ofs, upperpath, OVL_XATTR_UUID, uuid.b,
782 UUID_SIZE);
783 if (res == UUID_SIZE)
784 goto set_uuid;
785
786 if (res != -ENODATA)
787 goto fail;
788
789 /*
790 * With uuid=auto, if uuid xattr is found, it will be used.
791 * If uuid xattrs is not found, generate a persistent uuid only on mount
792 * of new overlays where upper root dir is not yet marked as impure.
793 * An upper dir is marked as impure on copy up or lookup of its subdirs.
794 */
795 if (ofs->config.uuid == OVL_UUID_AUTO) {
796 res = ovl_path_getxattr(ofs, upperpath, OVL_XATTR_IMPURE, NULL,
797 0);
798 if (res > 0) {
799 /* Any mount of old overlay - downgrade to uuid=null */
800 ofs->config.uuid = OVL_UUID_NULL;
801 return true;
802 } else if (res == -ENODATA) {
803 /* First mount of new overlay - upgrade to uuid=on */
804 ofs->config.uuid = OVL_UUID_ON;
805 } else if (res < 0) {
806 goto fail;
807 }
808
809 }
810
811 /* Generate overlay instance uuid */
812 uuid_gen(&uuid);
813
814 /* Try to store persistent uuid */
815 set = true;
816 res = ovl_setxattr(ofs, upperpath->dentry, OVL_XATTR_UUID, uuid.b,
817 UUID_SIZE);
818 if (res)
819 goto fail;
820
821 set_uuid:
822 super_set_uuid(sb, uuid.b, sizeof(uuid));
823 return true;
824
825 fail:
826 ofs->config.uuid = OVL_UUID_NULL;
827 pr_warn("failed to %s uuid (%pd2, err=%i); falling back to uuid=null.\n",
828 set ? "set" : "get", upperpath->dentry, res);
829 return false;
830 }
831
832 char ovl_get_dir_xattr_val(struct ovl_fs *ofs, const struct path *path,
833 enum ovl_xattr ox)
834 {
835 int res;
836 char val;
837
838 if (!d_is_dir(path->dentry))
839 return 0;
840
841 res = ovl_path_getxattr(ofs, path, ox, &val, 1);
842 return res == 1 ? val : 0;
843 }
844
845 #define OVL_XATTR_OPAQUE_POSTFIX "opaque"
846 #define OVL_XATTR_REDIRECT_POSTFIX "redirect"
847 #define OVL_XATTR_ORIGIN_POSTFIX "origin"
848 #define OVL_XATTR_IMPURE_POSTFIX "impure"
849 #define OVL_XATTR_NLINK_POSTFIX "nlink"
850 #define OVL_XATTR_UPPER_POSTFIX "upper"
851 #define OVL_XATTR_UUID_POSTFIX "uuid"
852 #define OVL_XATTR_METACOPY_POSTFIX "metacopy"
853 #define OVL_XATTR_PROTATTR_POSTFIX "protattr"
854 #define OVL_XATTR_XWHITEOUT_POSTFIX "whiteout"
855
856 #define OVL_XATTR_TAB_ENTRY(x) \
857 [x] = { [false] = OVL_XATTR_TRUSTED_PREFIX x ## _POSTFIX, \
858 [true] = OVL_XATTR_USER_PREFIX x ## _POSTFIX }
859
860 const char *const ovl_xattr_table[][2] = {
861 OVL_XATTR_TAB_ENTRY(OVL_XATTR_OPAQUE),
862 OVL_XATTR_TAB_ENTRY(OVL_XATTR_REDIRECT),
863 OVL_XATTR_TAB_ENTRY(OVL_XATTR_ORIGIN),
864 OVL_XATTR_TAB_ENTRY(OVL_XATTR_IMPURE),
865 OVL_XATTR_TAB_ENTRY(OVL_XATTR_NLINK),
866 OVL_XATTR_TAB_ENTRY(OVL_XATTR_UPPER),
867 OVL_XATTR_TAB_ENTRY(OVL_XATTR_UUID),
868 OVL_XATTR_TAB_ENTRY(OVL_XATTR_METACOPY),
869 OVL_XATTR_TAB_ENTRY(OVL_XATTR_PROTATTR),
870 OVL_XATTR_TAB_ENTRY(OVL_XATTR_XWHITEOUT),
871 };
872
873 int ovl_check_setxattr(struct ovl_fs *ofs, struct dentry *upperdentry,
874 enum ovl_xattr ox, const void *value, size_t size,
875 int xerr)
876 {
877 int err;
878
879 if (ofs->noxattr)
880 return xerr;
881
882 err = ovl_setxattr(ofs, upperdentry, ox, value, size);
883
884 if (err == -EOPNOTSUPP) {
885 pr_warn("cannot set %s xattr on upper\n", ovl_xattr(ofs, ox));
886 ofs->noxattr = true;
887 return xerr;
888 }
889
890 return err;
891 }
892
893 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
894 {
895 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
896 int err;
897
898 if (ovl_test_flag(OVL_IMPURE, d_inode(dentry)))
899 return 0;
900
901 /*
902 * Do not fail when upper doesn't support xattrs.
903 * Upper inodes won't have origin nor redirect xattr anyway.
904 */
905 err = ovl_check_setxattr(ofs, upperdentry, OVL_XATTR_IMPURE, "y", 1, 0);
906 if (!err)
907 ovl_set_flag(OVL_IMPURE, d_inode(dentry));
908
909 return err;
910 }
911
912
913 #define OVL_PROTATTR_MAX 32 /* Reserved for future flags */
914
915 void ovl_check_protattr(struct inode *inode, struct dentry *upper)
916 {
917 struct ovl_fs *ofs = OVL_FS(inode->i_sb);
918 u32 iflags = inode->i_flags & OVL_PROT_I_FLAGS_MASK;
919 char buf[OVL_PROTATTR_MAX+1];
920 int res, n;
921
922 res = ovl_getxattr_upper(ofs, upper, OVL_XATTR_PROTATTR, buf,
923 OVL_PROTATTR_MAX);
924 if (res < 0)
925 return;
926
927 /*
928 * Initialize inode flags from overlay.protattr xattr and upper inode
929 * flags. If upper inode has those fileattr flags set (i.e. from old
930 * kernel), we do not clear them on ovl_get_inode(), but we will clear
931 * them on next fileattr_set().
932 */
933 for (n = 0; n < res; n++) {
934 if (buf[n] == 'a')
935 iflags |= S_APPEND;
936 else if (buf[n] == 'i')
937 iflags |= S_IMMUTABLE;
938 else
939 break;
940 }
941
942 if (!res || n < res) {
943 pr_warn_ratelimited("incompatible overlay.protattr format (%pd2, len=%d)\n",
944 upper, res);
945 } else {
946 inode_set_flags(inode, iflags, OVL_PROT_I_FLAGS_MASK);
947 }
948 }
949
950 int ovl_set_protattr(struct inode *inode, struct dentry *upper,
951 struct fileattr *fa)
952 {
953 struct ovl_fs *ofs = OVL_FS(inode->i_sb);
954 char buf[OVL_PROTATTR_MAX];
955 int len = 0, err = 0;
956 u32 iflags = 0;
957
958 BUILD_BUG_ON(HWEIGHT32(OVL_PROT_FS_FLAGS_MASK) > OVL_PROTATTR_MAX);
959
960 if (fa->flags & FS_APPEND_FL) {
961 buf[len++] = 'a';
962 iflags |= S_APPEND;
963 }
964 if (fa->flags & FS_IMMUTABLE_FL) {
965 buf[len++] = 'i';
966 iflags |= S_IMMUTABLE;
967 }
968
969 /*
970 * Do not allow to set protection flags when upper doesn't support
971 * xattrs, because we do not set those fileattr flags on upper inode.
972 * Remove xattr if it exist and all protection flags are cleared.
973 */
974 if (len) {
975 err = ovl_check_setxattr(ofs, upper, OVL_XATTR_PROTATTR,
976 buf, len, -EPERM);
977 } else if (inode->i_flags & OVL_PROT_I_FLAGS_MASK) {
978 err = ovl_removexattr(ofs, upper, OVL_XATTR_PROTATTR);
979 if (err == -EOPNOTSUPP || err == -ENODATA)
980 err = 0;
981 }
982 if (err)
983 return err;
984
985 inode_set_flags(inode, iflags, OVL_PROT_I_FLAGS_MASK);
986
987 /* Mask out the fileattr flags that should not be set in upper inode */
988 fa->flags &= ~OVL_PROT_FS_FLAGS_MASK;
989 fa->fsx_xflags &= ~OVL_PROT_FSX_FLAGS_MASK;
990
991 return 0;
992 }
993
994 /*
995 * Caller must hold a reference to inode to prevent it from being freed while
996 * it is marked inuse.
997 */
998 bool ovl_inuse_trylock(struct dentry *dentry)
999 {
1000 struct inode *inode = d_inode(dentry);
1001 bool locked = false;
1002
1003 spin_lock(&inode->i_lock);
1004 if (!(inode->i_state & I_OVL_INUSE)) {
1005 inode->i_state |= I_OVL_INUSE;
1006 locked = true;
1007 }
1008 spin_unlock(&inode->i_lock);
1009
1010 return locked;
1011 }
1012
1013 void ovl_inuse_unlock(struct dentry *dentry)
1014 {
1015 if (dentry) {
1016 struct inode *inode = d_inode(dentry);
1017
1018 spin_lock(&inode->i_lock);
1019 WARN_ON(!(inode->i_state & I_OVL_INUSE));
1020 inode->i_state &= ~I_OVL_INUSE;
1021 spin_unlock(&inode->i_lock);
1022 }
1023 }
1024
1025 bool ovl_is_inuse(struct dentry *dentry)
1026 {
1027 struct inode *inode = d_inode(dentry);
1028 bool inuse;
1029
1030 spin_lock(&inode->i_lock);
1031 inuse = (inode->i_state & I_OVL_INUSE);
1032 spin_unlock(&inode->i_lock);
1033
1034 return inuse;
1035 }
1036
1037 /*
1038 * Does this overlay dentry need to be indexed on copy up?
1039 */
1040 bool ovl_need_index(struct dentry *dentry)
1041 {
1042 struct dentry *lower = ovl_dentry_lower(dentry);
1043
1044 if (!lower || !ovl_indexdir(dentry->d_sb))
1045 return false;
1046
1047 /* Index all files for NFS export and consistency verification */
1048 if (ovl_index_all(dentry->d_sb))
1049 return true;
1050
1051 /* Index only lower hardlinks on copy up */
1052 if (!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
1053 return true;
1054
1055 return false;
1056 }
1057
1058 /* Caller must hold OVL_I(inode)->lock */
1059 static void ovl_cleanup_index(struct dentry *dentry)
1060 {
1061 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
1062 struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
1063 struct inode *dir = indexdir->d_inode;
1064 struct dentry *lowerdentry = ovl_dentry_lower(dentry);
1065 struct dentry *upperdentry = ovl_dentry_upper(dentry);
1066 struct dentry *index = NULL;
1067 struct inode *inode;
1068 struct qstr name = { };
1069 bool got_write = false;
1070 int err;
1071
1072 err = ovl_get_index_name(ofs, lowerdentry, &name);
1073 if (err)
1074 goto fail;
1075
1076 err = ovl_want_write(dentry);
1077 if (err)
1078 goto fail;
1079
1080 got_write = true;
1081 inode = d_inode(upperdentry);
1082 if (!S_ISDIR(inode->i_mode) && inode->i_nlink != 1) {
1083 pr_warn_ratelimited("cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
1084 upperdentry, inode->i_ino, inode->i_nlink);
1085 /*
1086 * We either have a bug with persistent union nlink or a lower
1087 * hardlink was added while overlay is mounted. Adding a lower
1088 * hardlink and then unlinking all overlay hardlinks would drop
1089 * overlay nlink to zero before all upper inodes are unlinked.
1090 * As a safety measure, when that situation is detected, set
1091 * the overlay nlink to the index inode nlink minus one for the
1092 * index entry itself.
1093 */
1094 set_nlink(d_inode(dentry), inode->i_nlink - 1);
1095 ovl_set_nlink_upper(dentry);
1096 goto out;
1097 }
1098
1099 inode_lock_nested(dir, I_MUTEX_PARENT);
1100 index = ovl_lookup_upper(ofs, name.name, indexdir, name.len);
1101 err = PTR_ERR(index);
1102 if (IS_ERR(index)) {
1103 index = NULL;
1104 } else if (ovl_index_all(dentry->d_sb)) {
1105 /* Whiteout orphan index to block future open by handle */
1106 err = ovl_cleanup_and_whiteout(OVL_FS(dentry->d_sb),
1107 dir, index);
1108 } else {
1109 /* Cleanup orphan index entries */
1110 err = ovl_cleanup(ofs, dir, index);
1111 }
1112
1113 inode_unlock(dir);
1114 if (err)
1115 goto fail;
1116
1117 out:
1118 if (got_write)
1119 ovl_drop_write(dentry);
1120 kfree(name.name);
1121 dput(index);
1122 return;
1123
1124 fail:
1125 pr_err("cleanup index of '%pd2' failed (%i)\n", dentry, err);
1126 goto out;
1127 }
1128
1129 /*
1130 * Operations that change overlay inode and upper inode nlink need to be
1131 * synchronized with copy up for persistent nlink accounting.
1132 */
1133 int ovl_nlink_start(struct dentry *dentry)
1134 {
1135 struct inode *inode = d_inode(dentry);
1136 const struct cred *old_cred;
1137 int err;
1138
1139 if (WARN_ON(!inode))
1140 return -ENOENT;
1141
1142 /*
1143 * With inodes index is enabled, we store the union overlay nlink
1144 * in an xattr on the index inode. When whiting out an indexed lower,
1145 * we need to decrement the overlay persistent nlink, but before the
1146 * first copy up, we have no upper index inode to store the xattr.
1147 *
1148 * As a workaround, before whiteout/rename over an indexed lower,
1149 * copy up to create the upper index. Creating the upper index will
1150 * initialize the overlay nlink, so it could be dropped if unlink
1151 * or rename succeeds.
1152 *
1153 * TODO: implement metadata only index copy up when called with
1154 * ovl_copy_up_flags(dentry, O_PATH).
1155 */
1156 if (ovl_need_index(dentry) && !ovl_dentry_has_upper_alias(dentry)) {
1157 err = ovl_copy_up(dentry);
1158 if (err)
1159 return err;
1160 }
1161
1162 err = ovl_inode_lock_interruptible(inode);
1163 if (err)
1164 return err;
1165
1166 err = ovl_want_write(dentry);
1167 if (err)
1168 goto out_unlock;
1169
1170 if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode))
1171 return 0;
1172
1173 old_cred = ovl_override_creds(dentry->d_sb);
1174 /*
1175 * The overlay inode nlink should be incremented/decremented IFF the
1176 * upper operation succeeds, along with nlink change of upper inode.
1177 * Therefore, before link/unlink/rename, we store the union nlink
1178 * value relative to the upper inode nlink in an upper inode xattr.
1179 */
1180 err = ovl_set_nlink_upper(dentry);
1181 revert_creds(old_cred);
1182 if (err)
1183 goto out_drop_write;
1184
1185 return 0;
1186
1187 out_drop_write:
1188 ovl_drop_write(dentry);
1189 out_unlock:
1190 ovl_inode_unlock(inode);
1191
1192 return err;
1193 }
1194
1195 void ovl_nlink_end(struct dentry *dentry)
1196 {
1197 struct inode *inode = d_inode(dentry);
1198
1199 ovl_drop_write(dentry);
1200
1201 if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink == 0) {
1202 const struct cred *old_cred;
1203
1204 old_cred = ovl_override_creds(dentry->d_sb);
1205 ovl_cleanup_index(dentry);
1206 revert_creds(old_cred);
1207 }
1208
1209 ovl_inode_unlock(inode);
1210 }
1211
1212 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
1213 {
1214 struct dentry *trap;
1215
1216 /* Workdir should not be the same as upperdir */
1217 if (workdir == upperdir)
1218 goto err;
1219
1220 /* Workdir should not be subdir of upperdir and vice versa */
1221 trap = lock_rename(workdir, upperdir);
1222 if (IS_ERR(trap))
1223 goto err;
1224 if (trap)
1225 goto err_unlock;
1226
1227 return 0;
1228
1229 err_unlock:
1230 unlock_rename(workdir, upperdir);
1231 err:
1232 pr_err("failed to lock workdir+upperdir\n");
1233 return -EIO;
1234 }
1235
1236 /*
1237 * err < 0, 0 if no metacopy xattr, metacopy data size if xattr found.
1238 * an empty xattr returns OVL_METACOPY_MIN_SIZE to distinguish from no xattr value.
1239 */
1240 int ovl_check_metacopy_xattr(struct ovl_fs *ofs, const struct path *path,
1241 struct ovl_metacopy *data)
1242 {
1243 int res;
1244
1245 /* Only regular files can have metacopy xattr */
1246 if (!S_ISREG(d_inode(path->dentry)->i_mode))
1247 return 0;
1248
1249 res = ovl_path_getxattr(ofs, path, OVL_XATTR_METACOPY,
1250 data, data ? OVL_METACOPY_MAX_SIZE : 0);
1251 if (res < 0) {
1252 if (res == -ENODATA || res == -EOPNOTSUPP)
1253 return 0;
1254 /*
1255 * getxattr on user.* may fail with EACCES in case there's no
1256 * read permission on the inode. Not much we can do, other than
1257 * tell the caller that this is not a metacopy inode.
1258 */
1259 if (ofs->config.userxattr && res == -EACCES)
1260 return 0;
1261 goto out;
1262 }
1263
1264 if (res == 0) {
1265 /* Emulate empty data for zero size metacopy xattr */
1266 res = OVL_METACOPY_MIN_SIZE;
1267 if (data) {
1268 memset(data, 0, res);
1269 data->len = res;
1270 }
1271 } else if (res < OVL_METACOPY_MIN_SIZE) {
1272 pr_warn_ratelimited("metacopy file '%pd' has too small xattr\n",
1273 path->dentry);
1274 return -EIO;
1275 } else if (data) {
1276 if (data->version != 0) {
1277 pr_warn_ratelimited("metacopy file '%pd' has unsupported version\n",
1278 path->dentry);
1279 return -EIO;
1280 }
1281 if (res != data->len) {
1282 pr_warn_ratelimited("metacopy file '%pd' has invalid xattr size\n",
1283 path->dentry);
1284 return -EIO;
1285 }
1286 }
1287
1288 return res;
1289 out:
1290 pr_warn_ratelimited("failed to get metacopy (%i)\n", res);
1291 return res;
1292 }
1293
1294 int ovl_set_metacopy_xattr(struct ovl_fs *ofs, struct dentry *d, struct ovl_metacopy *metacopy)
1295 {
1296 size_t len = metacopy->len;
1297
1298 /* If no flags or digest fall back to empty metacopy file */
1299 if (metacopy->version == 0 && metacopy->flags == 0 && metacopy->digest_algo == 0)
1300 len = 0;
1301
1302 return ovl_check_setxattr(ofs, d, OVL_XATTR_METACOPY,
1303 metacopy, len, -EOPNOTSUPP);
1304 }
1305
1306 bool ovl_is_metacopy_dentry(struct dentry *dentry)
1307 {
1308 struct ovl_entry *oe = OVL_E(dentry);
1309
1310 if (!d_is_reg(dentry))
1311 return false;
1312
1313 if (ovl_dentry_upper(dentry)) {
1314 if (!ovl_has_upperdata(d_inode(dentry)))
1315 return true;
1316 return false;
1317 }
1318
1319 return (ovl_numlower(oe) > 1);
1320 }
1321
1322 char *ovl_get_redirect_xattr(struct ovl_fs *ofs, const struct path *path, int padding)
1323 {
1324 int res;
1325 char *s, *next, *buf = NULL;
1326
1327 res = ovl_path_getxattr(ofs, path, OVL_XATTR_REDIRECT, NULL, 0);
1328 if (res == -ENODATA || res == -EOPNOTSUPP)
1329 return NULL;
1330 if (res < 0)
1331 goto fail;
1332 if (res == 0)
1333 goto invalid;
1334
1335 buf = kzalloc(res + padding + 1, GFP_KERNEL);
1336 if (!buf)
1337 return ERR_PTR(-ENOMEM);
1338
1339 res = ovl_path_getxattr(ofs, path, OVL_XATTR_REDIRECT, buf, res);
1340 if (res < 0)
1341 goto fail;
1342 if (res == 0)
1343 goto invalid;
1344
1345 if (buf[0] == '/') {
1346 for (s = buf; *s++ == '/'; s = next) {
1347 next = strchrnul(s, '/');
1348 if (s == next)
1349 goto invalid;
1350 }
1351 } else {
1352 if (strchr(buf, '/') != NULL)
1353 goto invalid;
1354 }
1355
1356 return buf;
1357 invalid:
1358 pr_warn_ratelimited("invalid redirect (%s)\n", buf);
1359 res = -EINVAL;
1360 goto err_free;
1361 fail:
1362 pr_warn_ratelimited("failed to get redirect (%i)\n", res);
1363 err_free:
1364 kfree(buf);
1365 return ERR_PTR(res);
1366 }
1367
1368 /* Call with mounter creds as it may open the file */
1369 int ovl_ensure_verity_loaded(struct path *datapath)
1370 {
1371 struct inode *inode = d_inode(datapath->dentry);
1372 struct file *filp;
1373
1374 if (!fsverity_active(inode) && IS_VERITY(inode)) {
1375 /*
1376 * If this inode was not yet opened, the verity info hasn't been
1377 * loaded yet, so we need to do that here to force it into memory.
1378 */
1379 filp = kernel_file_open(datapath, O_RDONLY, current_cred());
1380 if (IS_ERR(filp))
1381 return PTR_ERR(filp);
1382 fput(filp);
1383 }
1384
1385 return 0;
1386 }
1387
1388 int ovl_validate_verity(struct ovl_fs *ofs,
1389 struct path *metapath,
1390 struct path *datapath)
1391 {
1392 struct ovl_metacopy metacopy_data;
1393 u8 actual_digest[FS_VERITY_MAX_DIGEST_SIZE];
1394 int xattr_digest_size, digest_size;
1395 int xattr_size, err;
1396 u8 verity_algo;
1397
1398 if (!ofs->config.verity_mode ||
1399 /* Verity only works on regular files */
1400 !S_ISREG(d_inode(metapath->dentry)->i_mode))
1401 return 0;
1402
1403 xattr_size = ovl_check_metacopy_xattr(ofs, metapath, &metacopy_data);
1404 if (xattr_size < 0)
1405 return xattr_size;
1406
1407 if (!xattr_size || !metacopy_data.digest_algo) {
1408 if (ofs->config.verity_mode == OVL_VERITY_REQUIRE) {
1409 pr_warn_ratelimited("metacopy file '%pd' has no digest specified\n",
1410 metapath->dentry);
1411 return -EIO;
1412 }
1413 return 0;
1414 }
1415
1416 xattr_digest_size = ovl_metadata_digest_size(&metacopy_data);
1417
1418 err = ovl_ensure_verity_loaded(datapath);
1419 if (err < 0) {
1420 pr_warn_ratelimited("lower file '%pd' failed to load fs-verity info\n",
1421 datapath->dentry);
1422 return -EIO;
1423 }
1424
1425 digest_size = fsverity_get_digest(d_inode(datapath->dentry), actual_digest,
1426 &verity_algo, NULL);
1427 if (digest_size == 0) {
1428 pr_warn_ratelimited("lower file '%pd' has no fs-verity digest\n", datapath->dentry);
1429 return -EIO;
1430 }
1431
1432 if (xattr_digest_size != digest_size ||
1433 metacopy_data.digest_algo != verity_algo ||
1434 memcmp(metacopy_data.digest, actual_digest, xattr_digest_size) != 0) {
1435 pr_warn_ratelimited("lower file '%pd' has the wrong fs-verity digest\n",
1436 datapath->dentry);
1437 return -EIO;
1438 }
1439
1440 return 0;
1441 }
1442
1443 int ovl_get_verity_digest(struct ovl_fs *ofs, struct path *src,
1444 struct ovl_metacopy *metacopy)
1445 {
1446 int err, digest_size;
1447
1448 if (!ofs->config.verity_mode || !S_ISREG(d_inode(src->dentry)->i_mode))
1449 return 0;
1450
1451 err = ovl_ensure_verity_loaded(src);
1452 if (err < 0) {
1453 pr_warn_ratelimited("lower file '%pd' failed to load fs-verity info\n",
1454 src->dentry);
1455 return -EIO;
1456 }
1457
1458 digest_size = fsverity_get_digest(d_inode(src->dentry),
1459 metacopy->digest, &metacopy->digest_algo, NULL);
1460 if (digest_size == 0 ||
1461 WARN_ON_ONCE(digest_size > FS_VERITY_MAX_DIGEST_SIZE)) {
1462 if (ofs->config.verity_mode == OVL_VERITY_REQUIRE) {
1463 pr_warn_ratelimited("lower file '%pd' has no fs-verity digest\n",
1464 src->dentry);
1465 return -EIO;
1466 }
1467 return 0;
1468 }
1469
1470 metacopy->len += digest_size;
1471 return 0;
1472 }
1473
1474 /*
1475 * ovl_sync_status() - Check fs sync status for volatile mounts
1476 *
1477 * Returns 1 if this is not a volatile mount and a real sync is required.
1478 *
1479 * Returns 0 if syncing can be skipped because mount is volatile, and no errors
1480 * have occurred on the upperdir since the mount.
1481 *
1482 * Returns -errno if it is a volatile mount, and the error that occurred since
1483 * the last mount. If the error code changes, it'll return the latest error
1484 * code.
1485 */
1486
1487 int ovl_sync_status(struct ovl_fs *ofs)
1488 {
1489 struct vfsmount *mnt;
1490
1491 if (ovl_should_sync(ofs))
1492 return 1;
1493
1494 mnt = ovl_upper_mnt(ofs);
1495 if (!mnt)
1496 return 0;
1497
1498 return errseq_check(&mnt->mnt_sb->s_wb_err, ofs->errseq);
1499 }
1500
1501 /*
1502 * ovl_copyattr() - copy inode attributes from layer to ovl inode
1503 *
1504 * When overlay copies inode information from an upper or lower layer to the
1505 * relevant overlay inode it will apply the idmapping of the upper or lower
1506 * layer when doing so ensuring that the ovl inode ownership will correctly
1507 * reflect the ownership of the idmapped upper or lower layer. For example, an
1508 * idmapped upper or lower layer mapping id 1001 to id 1000 will take care to
1509 * map any lower or upper inode owned by id 1001 to id 1000. These mapping
1510 * helpers are nops when the relevant layer isn't idmapped.
1511 */
1512 void ovl_copyattr(struct inode *inode)
1513 {
1514 struct path realpath;
1515 struct inode *realinode;
1516 struct mnt_idmap *real_idmap;
1517 vfsuid_t vfsuid;
1518 vfsgid_t vfsgid;
1519
1520 realinode = ovl_i_path_real(inode, &realpath);
1521 real_idmap = mnt_idmap(realpath.mnt);
1522
1523 spin_lock(&inode->i_lock);
1524 vfsuid = i_uid_into_vfsuid(real_idmap, realinode);
1525 vfsgid = i_gid_into_vfsgid(real_idmap, realinode);
1526
1527 inode->i_uid = vfsuid_into_kuid(vfsuid);
1528 inode->i_gid = vfsgid_into_kgid(vfsgid);
1529 inode->i_mode = realinode->i_mode;
1530 inode_set_atime_to_ts(inode, inode_get_atime(realinode));
1531 inode_set_mtime_to_ts(inode, inode_get_mtime(realinode));
1532 inode_set_ctime_to_ts(inode, inode_get_ctime(realinode));
1533 i_size_write(inode, i_size_read(realinode));
1534 spin_unlock(&inode->i_lock);
1535 }
1536
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